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WO2025119469A1 - Procédé de fabrication de produit absorbant sous forme de bande, produit absorbant sous forme de bande et appareil de fabrication d'un produit absorbant sous forme de bande - Google Patents

Procédé de fabrication de produit absorbant sous forme de bande, produit absorbant sous forme de bande et appareil de fabrication d'un produit absorbant sous forme de bande Download PDF

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Publication number
WO2025119469A1
WO2025119469A1 PCT/EP2023/084565 EP2023084565W WO2025119469A1 WO 2025119469 A1 WO2025119469 A1 WO 2025119469A1 EP 2023084565 W EP2023084565 W EP 2023084565W WO 2025119469 A1 WO2025119469 A1 WO 2025119469A1
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WO
WIPO (PCT)
Prior art keywords
foam
fibrous
weight
based product
less
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/EP2023/084565
Other languages
English (en)
Inventor
Stefan Raum
Hans-Jürgen Lamb
Corinne Munerelle
Nicolas Weisang
Antonia OXLEY
Elena VIVIANI
Tero Malm
Teijo ROKKONEN
Hannu Minkkinen
Janne Keränen
Olli-Ville LAUKKANEN
Antti Koponen
Annika KETOLA
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Essity Hygiene and Health AB
Original Assignee
Essity Hygiene and Health AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Essity Hygiene and Health AB filed Critical Essity Hygiene and Health AB
Priority to PCT/EP2023/084565 priority Critical patent/WO2025119469A1/fr
Publication of WO2025119469A1 publication Critical patent/WO2025119469A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F11/00—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines
    • D21F11/002—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines by using a foamed suspension
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
    • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
    • D21H21/22—Agents rendering paper porous, absorbent or bulky
    • D21H21/24—Surfactants
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
    • D21H21/50—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by form
    • D21H21/56—Foam

Definitions

  • the present disclosure concerns a method for manufacturing an absorbent web-based product, in particular by preparing and forming a fibrous foam into a foam layer, an absorbent web-based product, and an apparatus for manufacturing an absorbent web- based product.
  • TECHNICAL BACKGROUND Absorbent web-based products are widely used in modern society. Toilet paper, paper towels such as hand towels and household (kitchen) towels, wipes, facial tissues, napkins, tissue handkerchiefs etc. are basic commodities.
  • These products are usually manufactured by the wet-laid process, which consists of preparing an aqueous slurry of fibers (pulp slurry), feeding the slurry to a headbox spreading the slurry on a wire that allows the liquid to drain through while retaining most of the fibers in the form of a continuous web, pressing, drying and, optionally, winding and converting/confectioning to manufacture finished products.
  • pulp slurry aqueous slurry of fibers
  • WO 2016/173641 describes a wet-laid process for the manufacture of a tissue paper web comprising the steps of providing pulp fibers, forming an aqueous suspension of the fibers, feeding the suspension to a tissue-making headbox, depositing the suspension onto a wire to form a wet web, dewatering the wet web, and drying and creping the web.
  • the main physical properties of wet-laid products are, e.g., basis weight, strength, softness, absorbency, especially for aqueous systems, and resistance to lint and dust. While the wet-laid process can produce products with distinctive properties, it has been difficult to achieve lightweight, low- density absorbent products.
  • the manufacturing process still requires large amounts of water and energy, and finding more sustainable/environment friendly production methods would, hence, be desirable.
  • An alternative production method may rely on foam forming.
  • the foam forming process can be slower than the wet-laid process, which limits production efficiency and capacity.
  • it has proven difficult to achieve high quality products with high consistency when relying on foam forming techniques.
  • the present disclosure aims at addressing one or more of the above shortcomings.
  • a further object is to provide an apparatus for manufacturing an absorbent web-based product. Further objects will become apparent from the following detailed description.
  • the present disclosure provides a raw material and/or energy efficient process for manufacturing an absorbent web-based product.
  • the present disclosure relates to a method of manufacturing an absorbent web-based product comprising the steps of: - preparing a fibrous foam, wherein the preparing comprises dispersing fibers, one or more surface active agents in a liquid and/or a foam, with a fiber content of 5% to 60% by weight, a surface active agents content of 0.02% to 1.20% by weight, and a liquid content of 40% to 95% by weight, and supplying and dispersing gas in the liquid and/or the foam until a gas content of 64% or more by volume is reached; - forming the fibrous foam into a foam layer; - draining the fibrous foam in the foam layer to form a fibrous web, wherein the fibrous web has a liquid content of 20% to 85% by weight; and - drying the fibrous web to obtain an absorbent web-based product.
  • the foam may be prepared first and the dispersing of solids and of gas in the foam may then be performed.
  • the foam may be prepared, and solids may be dispersed in the liquid and in the foam.
  • the solids may be dispersed in the liquid.
  • the solids may comprise or consist of fibers.
  • the fiber content may be 5% to 60%, or 8% to 45% by weight, or 9% to 40% by weight, or 9.5% to 35% by weight, or 10% to 30% by weight, or 10% to 25% by weight, or 10% to 20% by weight;
  • the gas content may be 70% or more by volume, or 75%, or 80%, or 85%, or 90% or more by volume;
  • the surface active agents content may be 0.02% to 1.1% by weight, or 0.02% to 1.0% by weight, or 0.05% to 0.8% by weight; and the liquid content may be 40% to 95% by weight, or 55% to 92% by weight, or 53.9% to 91.8% by weight, or 65% to 85% by weight, or 78.9% to 89.95% by weight.
  • the liquid content may be 100% minus the sum of the surface active agents content and the fiber content.
  • the liquid content may be slightly lower, and the further content of a gas-dispersed liquid may be referred to as the remainder.
  • the present disclosure also relates to a method of manufacturing an absorbent web-based product including the steps of: - preparing a fibrous foam by supplying fibers and one or more surface active agents to a liquid and/or a foam, and dispersing gas in the liquid and/or the foam, reaching a fiber volume fraction of 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or less, or 0.005 or less; - forming the fibrous foam into a foam layer; - draining the fibrous foam in the foam layer to form a fibrous web, wherein the fibrous web has a liquid content of 20% to 85% by weight; and - drying the fibrous web to obtain an absorbent
  • the foam may be prepared first and the dispersing of solids and of gas in the foam may then be performed.
  • the foam may be prepared, and solids may be dispersed in the liquid and in the foam.
  • the solids may be dispersed in the liquid.
  • the solids may comprise or consist of fibers.
  • the present disclosure provides an absorbent web- based product having excellent properties, especially one or more of an excellent basis weight, softness, strength and absorbency.
  • the present disclosure relates to an absorbent web-based product that is manufacturable by the above methods.
  • the present disclosure also relates to an absorbent web-based product comprising at least 70 wt.-% of fiber material based on the total weight of the absorbent web-based product, wherein the absorbent web-based product has a basis weight of 5g/m or more, or 8g/m or more, or 10g/m or more, and 500g/m2 or less, or 300g/m2 or less, or 200g/m2 or less, or 150g/m2 or less, or 10 to 120 g/m and a density of 5 to 200kg/m3, or 8 to 150kg/m3, or 10 to 100 kg/m, or 10 to 70 kg/m.
  • the present disclosure provides an apparatus for manufacturing an absorbent web-based product.
  • the present disclosure relates to an apparatus for manufacturing an absorbent web-based product
  • a fibrous foam preparation means preparing a fibrous foam, - a foam layer formation means forming the fibrous foam into a foam layer; - a draining means draining the fibrous foam in the foam layer to form a fibrous web having a liquid content of 20% to 85% by weight; and - a drying means that dries the fibrous web to obtain an absorbent web-based product
  • the fibrous foam preparation means comprises a supply means that supplies fibers, one or more surface active agents, a liquid, and gas, wherein a fiber content is 5% to 60% by weight, a surface active agents content is 0.02% to 1.20% by weight, a liquid content is 40% to 95% by weight, and a gas content is 64% or more by volume.
  • the present disclosure also relates to an apparatus for manufacturing an absorbent web-based product comprising: - a fibrous foam preparation means preparing a fibrous foam, - a foam layer formation means forming the fibrous foam into a foam layer; - a draining means draining the fibrous foam in the foam layer to form a fibrous web having a liquid content of 20% to 85% by weight; and - a drying means that dries the fibrous web to obtain an absorbent web-based product, wherein the fibrous foam preparation means prepares the fibrous foam with fibers, a liquid, and gas, and with a fiber volume fraction of 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or less, or 0.005 or less.
  • a method of manufacturing an absorbent web-based product including the steps of: - preparing a fibrous foam, wherein the preparing comprises dispersing fibers and one or more surface active agents in a liquid and/or a foam, with a fiber content of 5% to 60% by weight, a surface active agents content of 0.02% to 1.20% by weight, and a liquid content of 40% to 95% by weight and supplying and dispersing gas in the liquid and/or the foam until a gas content of 64% or more by volume is reached; - forming the fibrous foam into a foam layer; - draining the fibrous foam in the foam layer to form a fibrous web, wherein the fibrous web has a liquid content of 20% to 85% by weight; and - drying the fibrous web to obtain an absorbent web-based product.
  • a feedback loop control optionally including measuring at least one of a gas content, a density of a gas-liquid dispersion, and a conductivity of a gas-liquid dispersion, and adding and dispersing gas until at least one of the gas content, the density, and the conductivity reaches a target value.
  • the preparing comprises supplying the gas and the liquid into a vessel such that a ratio between the amount of liquid supplied and the amount of gas supplied lies in a predetermined range or amounts to a predetermined value, and mechanically mixing in the vessel for at least a predetermined amount of time or until a foam parameter, such as a foam height and/or a gas content reaches a predetermined minimum threshold.
  • a foam parameter such as a foam height and/or a gas content reaches a predetermined minimum threshold.
  • the liquid comprises at least 80% by weight of water, and/or the gas used to prepare the fibrous foam comprises at least 95% air by volume.
  • the fibrous foam comprises a liquid with at least 80% by weight of water, and/or a gas with at least 95% air by volume. 7.
  • a method of manufacturing an absorbent web-based product including the steps of: - preparing a fibrous foam by supplying fibers and one or more surface active agents to a liquid and/or a foam and dispersing gas in the liquid and/or the foam, thereby reaching a fiber volume fraction of 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or less, or 0.005 or less; - forming the fibrous foam into a foam layer; - draining the fibrous foam in the foam layer to form a fibrous web, wherein the fibrous web has a liquid content of 20% to 85% by weight; and - drying the fibrous web to obtain an absorbent web-based product.
  • the prepared fibrous foam comprises solids, and a solids volume fraction is 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or less, or 0.005 or less, and wherein at least 80% by weight of the solids is fibers.
  • a fiber content is 5% to 60% by weight, and/or a liquid content is 40% to 95% by weight, and a gas content is 64% or more by volume, optionally at least 70%, at least 75%, at least 80%, at least 85%, or at least 90% by volume.
  • the preparing comprises processing dry fibers or solids, moisturized fibers or solids, a liquid slurry or a foam and fibers into the fibrous foam.
  • the processing is performed prior to the transporting, or wherein the processing is at least partially performed by a transporting means that transports the fibrous foam to a forming means that forms the fibrous foam into the foam layer, wherein, optionally, the processing is performed by the transporting means. 12.
  • the processing comprises increasing a pressure applied to the liquid slurry or the fibrous foam during the transporting by the transporting means in a downstream direction of transportation, wherein the increasing of the pressure, optionally, is an increase of at least 0.1 bar and, optionally, 10 bars or less. 14.
  • the method of item 12 or 13, wherein the processing comprises successively applying a plurality of different pressure levels in the downstream direction, wherein the pressure level is optionally decreased twice or more and/or the pressure level is optionally increased twice or more.
  • the processing comprises at least one of: shear, elongational, and/or distributive mixing, defiberizing, deflocculating, refining, dispersing, disintegrating, changing fiber shapes, heating, and adding chemical additives.
  • the method of any one of the preceding items, wherein the preparing comprises supplying a rheology modifier.
  • the method of any one of the preceding items, wherein the draining of the fibrous foam comprises, optionally, consists of mechanical draining.
  • the absorbent web-based product has a liquid content of 0.5% to 15% by weight, optionally, 1% to 15% by weight, or 1% to 10% by weight, or 1.5% to 8% by weight, or 1.8% to 6.5% by weight, or 2% to 5% by weight, wherein, optionally, the absorbent web-based product has a water content of 0.5% to 10% by weight, optionally, 1% to 10% by weight, or 1.5% to 8% by weight, or 1.8% to 6.5% by weight, or 2% to 5% by weight.
  • the prepared fibrous foam has a solids content of more than 10% by weight, optionally a fiber content of more than 10% by weight.
  • the method of any one of the preceding items, wherein the forming of the fibrous foam into a foam layer comprises bringing the fibrous foam into a planar form.
  • the method of any one of the preceding items comprising bringing the fibrous foam into contact with at least one rotatable means and rotating the at least one rotatable means to transport the fibrous foam, optionally rotating the at least one rotatable means with from 100 to 5000 revolutions per minute.
  • the method of item 21, wherein the rotating of the at least one rotatable means promotes defiberizing at least a part, optionally all of the fibers.
  • an industrial mixer a screw kneader, an industrial kneading machine, an extruder, a mono- or twin-screw machine, a mono- or twin-screw continuous kneader, a twin-screw or multiple-screw machine, a conical screw mixer, comprising the at least one rotatable means.
  • the method of item 23, comprising supplying, to the fibrous foam when transporting the fibrous foam through the processing device, at least one component selected from the following list: - a liquid, such as water, optionally comprising one or more additives; - a gas, such as air; - a foam and/or a liquid slurry; and - a solid, such as fibers, powder, and/or granulate. 26.
  • a screw assembly such as an extruder or a screw mixer
  • any one of items 21 to 27, wherein the at least one rotatable means comprises at least a first screw and a second screw, and a distance of closest approach between the first screw and the second screw during rotations is in the range of from 0.3 mm to 20 mm. 29.
  • the at least one rotatable means comprises a plurality of screws and at least one housing that houses the plurality of screws, and a distance of closest approach between any screw amongst the plurality of screws and an opposing inner surface of the at least one housing that houses the any screw is in the range of from 0.3 mm to 20 mm.
  • any one of the preceding items wherein the fibrous foam is displaced, prior to the forming, by a displacement pump, optionally, a rotary lobe pump, a progressing cavity pump, a rotary gear pump, a piston pump, a diaphragm pump, a screw pump, a gear pump, a hydraulic pump, a rotary vane pump, a peristaltic pump, a rope pump, or a flexible impeller pump.
  • the draining comprises applying a vacuum to the foam layer with a constant pressure or with a varying pressure, wherein the varying pressure is, optionally, a pressure that has at least one decrease in a downstream direction of transportation.
  • any one of the preceding items wherein the draining is performed by successively applying at least two stages of vacuum to the foam layer, optionally, with a decreasing pressure.
  • the forming of the fibrous foam into the foam layer is at least in part performed in a die and/or a headbox and/or a cylindrical mold former, and/or a suction breast roll former, and/or wherein the processing and/or the forming of the foam layer is performed in a controlled pressure chamber, wherein, optionally, the die is a slot die with an adjustable die gap, wherein the fibrous foam is processed into a continuous fibrous web or sheet on a moving continuous dewatering/conveyor unit.
  • any one of the preceding items comprising, prior to the step of preparing the fibrous foam, a step of preparing a slurry comprising at least one component selected from the group consisting of: water, fibers, a surface active agent, a binder, and a slipping agent; wherein the preparing of the slurry is optionally at least partially performed in a high consistency mixing apparatus.
  • the drying is thermal, freeze, infrared, contact, impingement, microwave, or through air drying.
  • the preparing of the fibrous foam comprises supplying at least one surface active agent or a mixture of surface active agents, the surface active agent(s) being optionally selected from anionic surface active agents, cationic surface active agents, zwitterionic surface active agents, amphoteric surface active agents, and nonionic surface active agents.
  • the preparing of the fibrous foam comprises supplying at least one nonionic surface active agent or a mixture of surface active agents comprising at least one nonionic surface active agent, the nonionic surface active agent(s) being optionally selected from the group consisting of amine oxides, alkylglucosides, alkylpolyglucosides, polyhydroxy fatty acid amides, alkoxylated mono- and di-fatty acid esters, alkoxylated fatty alcohols, alkoxylated alkylphenols, fatty acid monoglycerides, polyoxyethylene s orbitan, and sucrose esters. 38.
  • the at least one nonionic surface active agent is selected from the group consisting of alkylglucosides, alkylpolyglucosides, and alkoxylated fatty alcohols, the at least one nonionic surface active agent being optionally an alkylpolyglucoside of the general formula (1): R 1-O-(R2)n-H (1) wherein, R 1 is a linear or branched hydrocarbon group having from 4 to 20 carbon atoms, R 2 is a hexose or pentose unit, n is 1 to 5. 39. The method of any one of the preceding items, wherein the preparing of the fibrous foam and transporting the fibrous foam to the foam layer formation means is promoted by the same mechanical movement. 40.
  • a method of manufacturing an end product comprising the method of any one of the preceding items, and comprising after the drying, at least one of the following steps: web handling, winding, confectioning, and converting into a packaged or unpackaged end product. 41. An absorbent web-based product that is manufacturable by the method according to any one of the preceding items. 42.
  • the absorbent web-based product of item 41 having a basis weight of 5 to 500g/m2 and a density of 5 to 200kg/m3 and/or w herein a variation ⁇ of the basis weight measured in accordance with SCAN-P 92:09 is less than 20%, less than 15%, less than 10%, less than 5%, less than 3%, or less than 2% of the mean basis weight of the absorbent web-based product.
  • An absorbent web-based product comprising at least 70 wt.- % of fiber material based on the total weight of the absorbent web-based product, wherein the absorbent web-based product has a basis weight of 5 to 500g/m2 and a density of 5 to 200kg/m3.
  • the absorbent web-based product of item 43 wherein a v ariation ⁇ of the basis weight measured in accordance with SCAN-P 92:09 is less than 20%, less than 15%, less than 10%, less than 5%, less than 3%, or less than 2% of the mean basis weight of the absorbent web-based product.
  • a v ariation ⁇ of the basis weight measured in accordance with SCAN-P 92:09 is less than 20%, less than 15%, less than 10%, less than 5%, less than 3%, or less than 2% of the mean basis weight of the absorbent web-based product.
  • 45 The absorbent web-based product of item 43 or 44, wherein the absorbent web-based product has an upper side and a lower side, and a density in a central region of the absorbent web-based product located between the upper and lower sides in a thickness direction is lower than a density in a region of the absorbent web-based product located at the lower and/or upper side(s). 46.
  • the absorbent web-based product of item 43 to 45 comprising a surface active agent.
  • the absorbent web-based product of any one of items 43 to 46 which comprises one or more of the following (a) to (d): (a) at least 0.2 wt.-% of one or more binders, (b) at least 0.05 wt.-% of one or more rheology modifiers, (c) at least 0.01 wt.-% of one or more surface active agents, and (d) at least 0.2 wt.-% of one or more slipping agents, each based on the total weight of the absorbent web- based product. 48.
  • a multi-ply product comprising at least one ply that is made of the absorbent web-based product of any one of items 43 to 47, optionally further comprising at least one non- woven ply and/or at least one tissue paper ply, optionally a conventional wet press paper ply and/or a structured ply and/or a textured ply. 49.
  • An apparatus for manufacturing an absorbent web-based product comprising: - a fibrous foam preparation means preparing a fibrous foam, - a foam layer formation means forming the fibrous foam into a foam layer; - a draining means draining the fibrous foam in the foam layer to form a fibrous web having a liquid content of 20% to 85% by weight; and - a drying means that dries the fibrous web to obtain an absorbent web-based product, wherein the fibrous foam preparation means comprises a supply means that supplies fibers, one or more surface active agents, a liquid, and gas, wherein a fiber content is 5% to 60% by weight, a surface active agents content is 0.02% to 1.20% by weight, a liquid content is 40% to 95% by weight, and a gas content is 64% or more by volume.
  • the fibrous foam preparation means comprises a solids supply means that supplies solids, wherein a solids content is 5% to 60% by weight, and wherein at least 80% by weight of the solids are fibers.
  • the supply means supplies liquid and/or a foam, in which the surface active agents, the fibers, and the gas are dispersed, comprising at least 80% by weight of water, and/or gas being dispersed in the liquid and/or the foam comprising at least 95% air by volume.
  • any one of items 49 to 51, wherein the fibrous foam preparation means prepares a gas-liquid dispersion that comprises a liquid content of at least 80% by weight of water, and/or a gas content of at least 95% air by volume.
  • An apparatus for manufacturing an absorbent web-based product comprising: - a fibrous foam preparation means preparing a fibrous foam, - a foam layer formation means forming the fibrous foam into a foam layer; - a draining means draining the fibrous foam in the foam layer to form a fibrous web having a liquid content of 20% to 85% by weight; and - a drying means that dries the fibrous web to obtain an absorbent web-based product, wherein the fibrous foam preparation means prepares the fibrous foam with fibers, a liquid, and gas, and with a fiber volume fraction of 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or
  • the fibrous foam preparation means prepares the fibrous foam with a solids content, wherein a solids volume fraction is 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or less, or 0.005 or less, and wherein at least 80% of the solids content is the fiber content. 55.
  • a fiber content is 5% to 60% by weight, and/or a liquid content is 40% to 95% by weight, and a gas content is 64% or more by volume, optionally at least 70%, at least 75%, or at least 80%, or at least 85%, or at least 90%, by volume.
  • the fibrous foam preparation means comprises a processing means that processes a liquid slurry or a foam and fibers into the fibrous foam.
  • the apparatus of item 56 comprising a transporting means that transports the liquid slurry, and/or the foam, and/or the fibrous foam to the foam layer formation means, wherein, optionally, the transporting means performs at least a part of the processing or performs the processing, wherein, optionally, the transporting means performs the processing.
  • the apparatus of item 56 or 57 wherein one or several of the following components are part of one integral structural unit: the processing means, the fibrous foam preparation means, the transporting means, the forming means, and the draining means.
  • the apparatus of item 57 or item 58 as dependent on item 57, wherein the transporting means comprises a pressurization section that increases a pressure applied to the liquid slurry or the fibrous foam during the transporting by the transporting means in a downstream direction of transportation, wherein the increasing of the pressure, optionally, is an increase of at least 0.1 bar and, optionally, 10 bars or less.
  • the pressurization section successively applies a plurality of different pressure levels in the downstream direction, the pressure levels being decreased at least twice and/or increased at least twice.
  • the apparatus of any one of items 56 to 60 wherein the processing means performs at least one of the following: shear, elongational, and/or distributive mixing, defiberizing, deflocculating, refining, dispersing, disintegrating, changing fiber shapes, heating, and adding chemical additives.
  • the fibrous foam preparation means promotes the preparing of the fibrous foam and transporting the fibrous foam to the foam layer formation means by the same mechanical movement, and/or wherein the fibrous foam preparation means transports the fibrous foam to the forming means.
  • the apparatus for manufacturing an absorbent web-based product of any one of items 49 to 62 further comprising one or several solids supply means supplying solids to the fibrous foam preparation means, and one or several liquid supply means supplying liquid to the fibrous foam preparation means, to form the fibrous foam with a solids content of 5% to 60% by weight of the fibrous foam, optionally of more than 10% by weight of the fibrous foam, and a liquid content of 40% to 95% by weight of the fibrous foam.
  • the apparatus for manufacturing an absorbent web-based product of any one of items 49 to 63 wherein the fibrous foam preparation means comprises a rheology modifier supply means that supplies a rheology modifier.
  • the apparatus for manufacturing an absorbent web-based product of any one of items 49 to 67 comprising at least one rotatable means, the apparatus bringing the fibrous foam into contact with the at least one rotatable means and rotating the at least one rotatable means to transport the fibrous foam, optionally rotating the at least one rotatable means with from 100 to 5000 revolutions per minute.
  • the apparatus for manufacturing an absorbent web-based product of item 68 or 69 comprising at least one processing device selected from the following list: an industrial mixer, a screw kneader, an industrial kneading machine, an extruder, a mono or twin screw machine, a mono or twin screw continuous kneader, a twin screw or multiple screw machine, a conical screw mixer, comprising the at least one rotatable means. 71.
  • the apparatus for manufacturing an absorbent web-based product of any one of items 68 to 70 comprising a housing that houses the rotatable means, wherein a minimum distance between the rotatable means and an opposing inner surface of the housing is in the range of 0.2 to 20% of a diameter of the at least one rotatable means, and, optionally, in the range of 0.3 to 20 mm. 72.
  • the apparatus for manufacturing an absorbent web-based product of item 70 or 71 comprising a supply means supplying, while the fibrous foam is transported through the processing device, at least one component selected from the following list: - a liquid, such as water, optionally comprising one or more additives; - a gas, such as air; - a foam and/or a liquid slurry; and - a solid, such as fibers, powder and/or granulate.
  • the apparatus for manufacturing an absorbent web-based product of any one of items 70 to 72 wherein the at least one rotatable means is a twin screw, a single screw, or a multiple screw, and the at least one rotatable means optionally comprises one or several of the following sections: an acceleration section that accelerates the fibrous foam being transported through the processing device; a deceleration section that decelerates the fibrous foam being transported through the processing device; a shear and/or elongation application section that applies a shear and/or elongation force to the fibrous foam.
  • the apparatus for manufacturing an absorbent web-based product of any one of items 70 to 73 comprising a screw assembly that comprises a housing and the at least one screw, wherein a minimum distance, in a cross-section of the at least one screw perpendicular to a rotational axis, between the at least one screw and an opposing inner surface of the housing is in the range of from 1% to 20% of an outer diameter of the screw, optionally in the range of from 0.3 mm to 20 mm.
  • the apparatus for manufacturing an absorbent web-based product of items 70 to 75, wherein the at least one rotatable means comprises a plurality of screws and at least one housing that houses the plurality of screws, and a distance of closest approach between any screw amongst the plurality of screws and an opposing inner surface of the at least one housing that houses the any screw is in the range of from 0.3 mm to 20 mm. 77.
  • the apparatus for manufacturing an absorbent web-based product of any one of items 49 to 76 comprising a displacement pump, optionally, a rotary lobe pump, a progressing cavity pump, a rotary gear pump, a piston pump, a diaphragm pump, a screw pump, a gear pump, a hydraulic pump, a rotary vane pump, a peristaltic pump, a rope pump, a flexible impeller pump, that, prior to the forming, displaces the fibrous foam.
  • a displacement pump optionally, a rotary lobe pump, a progressing cavity pump, a rotary gear pump, a piston pump, a diaphragm pump, a screw pump, a gear pump, a hydraulic pump, a rotary vane pump, a peristaltic pump, a rope pump, a flexible impeller pump, that, prior to the forming, displaces the fibrous foam.
  • the apparatus for manufacturing an absorbent web-based product of any one of items 49 to 77 wherein the draining means applies a vacuum to the foam layer with a constant pressure or with a varying pressure, wherein the varying pressure is, optionally, a pressure that has at least one decrease in a downstream direction of transportation.
  • the foam layer formation means comprises a die and/or a headbox and/or a cylindrical mold former and/or a suction breast roll former.
  • a liquid slurry preparation device that prepares an intermediate mixture/slurry foam/slurry solution comprising at least one component selected from the group consisting of: water, fibers, one or more surface active agents, one or more binders, and one or more slipping agents; the liquid slurry preparation device optionally comprising in a high consistency mixing apparatus.
  • the apparatus for manufacturing an absorbent web-based product of any one of items 49 to 82 wherein the drying means is a thermal, freeze, infrared, contact, impingement, microwave, or through air drying means.
  • the apparatus for manufacturing an absorbent web-based product of any one of items 45 to 83 comprising a surface active agent supply means that supplies at least one surface active agent or a mixture of surface active agents, the surface active agent(s) being optionally selected from anionic surface active agents, cationic surface active agents, amphoteric surface active agents, zwitterionic surface active agents, and nonionic surface active agents.
  • the apparatus for manufacturing an absorbent web-based product of any one of items 45 to 84 comprising a temperature control means that controls a temperature inside at least one section of the apparatus.
  • the apparatus for manufacturing an absorbent web-based product of any one of items 45 to 85 comprising a control device that controls the apparatus to perform the method of any one of items 1 to 39.
  • An apparatus for manufacturing an end product comprising the apparatus of any one of items 45 to 86, and at least one of the following components: a web handling device, a winding device, a confectioning device, and a conversion device that converts into a packaged or unpackaged end product.
  • absorbent web-based product refers to a product having a web-like structure containing fibers and optionally other additives, and being capable of absorbing liquids, moisture, or other substances.
  • web refers to a structure such as a fabric, sheet, or material in which individual fibers lie interlaid.
  • the term “absorbent product” characterizes a product with a water-absorption capacity of 4 g/g or more, or 5 g/g or more, or 6 g/g or more, or 10 g/g or more, or 15 g/g or more, or 20 g/g or more as measured, for example, in accordance with ISO 12625-8:2010.
  • the water-absorption time may be from 1 s to 25 s as measured, for example, in accordance with ISO 12625-8:2010.
  • an “absorbent web-based product” generally refers to a product with at least one ply, wherein a basis weight per ply may be 5g/m or more, or 8g/m or more, or 10g/m or more, and 500g/m2 or less, or 300g/m2 or less, or 200g/m2 or less, or 150g/m2 or less, or 120 g/m or less.
  • the basis weight (grammage) of the (single-ply) absorbent web-based product may be from 5 to 500 g/m, or 10 to 120g/m Further, the density of the (single-ply) absorbent web-based product may be from 5 to 200kg/m3, or 1 to 100kg/m, or 8 to 150kg/m3, or 10 to 70 kg/m.
  • the absorbent web-based product may be a single-ply product or a multi-ply product that is tailored to the end user’s needs by further converting steps.
  • the absorbent web-based product is a single-ply product.
  • tissue paper refers to a base paper produced by a tissue machine and comprising natural fibers.
  • tissue paper ply refers to a ply of tissue paper as obtained from the tissue machine. The tissue paper ply is made by a process comprising the steps of: forming an aqueous suspension of pulp fibers, depositing the aqueous suspension onto a wire to form a wet web, dewatering, drying, and creping of the web.
  • each individual ply of the absorbent web-based product may consist of a fibrous web comprising one or more layers, e.g., one, two, three or four layers.
  • a fibrous web comprising one or more layers, e.g., one, two, three or four layers.
  • layers we understand a stratum within the web having a defined fiber composition.
  • the one or more layers can be formed by depositing one or more streams of foams or furnishes onto a wire with a pressurized single- or multi-layered headbox to form a “multi- layered” fibrous web.
  • the present disclosure encompasses a multi-ply product comprising at least one ply that is made of absorbent web-based product with any one or several of the features described.
  • the multi-ply product may comprise two or more plies made of absorbent web-based product.
  • the multi-ply product may comprise one or several plies (which may be mutually the same or mutually different) of other types.
  • the multi-ply product may comprise one or several tissue paper plies.
  • Each of the tissue paper plies may be a conventional wet paper ply, e.g., a structured ply, such as a TAD ply, an ATMOS ply, a creped tissue paper ply, etc., or a textured ply.
  • fibrous foam refers to a foam that comprises fibers.
  • the term “foam” describes a cellular structure of gas bubbles separated by soft solid films or by a liquid media.
  • the properties of the fibrous foam depend, in particular, on the air content and fiber consistency in the foaming slurry (which in turn determine the fiber volume fraction of the foam) as well as on the types of fibers used and the size and size distribution of the bubbles.
  • Rheological properties of fibrous foam samples can be measured with a stress-controlled TA Instruments DHR-2 rheometer equipped with a vane-in-cup geometry.
  • the vane is a commercial 4-bladed vane geometry made out of stainless steel and having a diameter of 15 mm.
  • the cup is 3D-printed by stereolithography and has a diameter of 30 mm.
  • the outer wall of the cup is vertically profiled to eliminate wall slip during the rheological measurements.
  • the cup is placed in a temperature-controlled Peltier jacket that keeps the temperature of the sample at 25 °C during all rheological measurements.
  • Fibrous foam samples are loaded into the cup with the help of a syringe whose end is cut open, making sure that the whole cup is filled with fibrous foam and that there are no air pockets inside the sample.
  • the air content of the fibrous foam sample is determined by weighing the foam-filled cup before inserting it into the rheometer.
  • rheological measurements can, for example, be performed for fibrous foam samples: 1) Amplitude sweep measurement from 0.01 to 100 % strain amplitude at a constant angular frequency of 10 rad/s; 2) Frequency sweep measurement from 0.4 to 100 rad/s at a strain amplitude of 0.03 %; and 3) Shear rate sweep measurement first from the shear rate of 0.1 to 100 s-1 (“up-curve”) and then from the shear rate of 100 to 0.01 s-1 (“down-curve”).
  • surface active agent refers to any agent which, even at low concentrations, effectively lowers the surface tension of a liquid, for example water, by selective adsorption on the interface.
  • the surface active agent can be a pure chemical compound or a mixture of different chemical compounds. Examples of surface active agents include anionic, non-ionic, cationic, amphoteric, zwitterionic surface active agents, and combinations thereof.
  • fiber volume fraction refers to the ratio between the volume of the fibers and the volume of liquid, gas, and solids (V /(V + V + V )) in the fibrous foam.
  • solids volume fraction refers to the ratio between the volume of the solids and the volume of liquid, gas, and solids (V /(V + V + V )) in the fibrous foam.
  • the volume of a liquid (V ) can be determined using standard calibrated volumetric instruments, such as pipettes, burettes, graduated cylinders, and volumetric flasks. These instruments can be used to measure the volume of a liquid with high precision and accuracy. Such instruments can be calibrated according to ISO 4787:2021.
  • the volume of fibers (V ) is defined as the ratio of fiber mass to fiber density.
  • the fiber density – i.e., solids that are porous or have internal voids – can be determined by using, for example, the gas pycnometry method described in ISO 12154:2014. That is, the volume of solids is determined by measuring the change in pressure when a known volume of gas is displaced by the solids in a closed chamber. The fiber density can be calculated as the ratio of the mass to the gas-displaced volume.
  • Typical fiber densities in the manufacturing method are from 0.90 to 1.80 g/cm (e.g., spruce kraft: 1.5 g/cm, eucalyptus kraft: 1.5 g/cm, single cellulose: 1.5 g/cm, flax: 1.43-1.52 g/cm, hemp: 1.47-1.50 g/cm, viscose: 1.52 g/cm, nylon 6,6: 1.14 g/cm, polyester: 1.38 g/cm, polypropylene: 0.90 g/cm).
  • the volume of solids (V ) is defined as the sum of the volumes of every solid ⁇ i ⁇ present in the fibrous foam.
  • the volume ⁇ i ⁇ can be defined as the ratio between the mass and the density of the solid ⁇ i ⁇ .
  • the density of the solids can be determined as follows: - The density of solids that have regular shapes and can be measured with a ruler or a caliper can be determined by using direct measurement of mass and volume. The mass can be measured with a balance and the volume can be calculated from the dimensions. The density is then the ratio of mass to volume; - The density of solids that have irregular shapes and cannot be measured directly can be determined by using indirect volume measurement. The volume can be determined by displacing a known amount of liquid or gas with the solid and measuring the difference.
  • the density is then the ratio of mass to displaced volume; -
  • the density of solids that are insoluble and non-porous can be determined by using hydrostatic weighing.
  • the mass of the solid is measured in air and then in water (or another liquid).
  • the difference in mass is equal to the buoyant force exerted by the liquid on the solid.
  • the density is then calculated from the mass difference and the density of the liquid; -
  • the density of solids that are porous or have internal voids can be determined by using, e.g., the gas pycnometry methodology as described in the norm ISO12154:2014.
  • the volume of the solid is determined by measuring the pressure change when a known amount of gas is displaced by the solid in a closed chamber.
  • the density is then the ratio of mass to gas-displaced volume.
  • the volume of gas (V ) can be determined by measuring the gas content of the fibrous foam. After measurement of V , V and V , the initial volume of the liquid prior to the foaming can be calculated as the sum of all those volumes. After the foaming, the volume of the fibrous foam (V ) can be determined with standard calibrated volumetric instruments such as pipettes, burettes, graduated cylinders, and volumetric flasks. These instruments can be used to measure the volume of a foam with high precision and accuracy. Such instruments can be calibrated according to ISO 4787:2021.
  • liquid slurry refers to a liquid-solid suspension or a mixture of chemical components.
  • the liquid slurry may, e.g., result from a liquid and a solid being contacted in a reactor or mixer.
  • a liquid slurry may offer the benefit of better handling of the solid in the slurry and to obtain certain chemical reactions, or certain physical interactions, like the trapping of some aroma of the solids in the liquid.
  • fiber refers to an elongated solid object having an apparent length greatly exceeding its apparent width, i.e., a length to diameter ratio of at least about 5, or at least about 10.
  • Fibers are typically considered discontinuous in nature.
  • Non-limiting examples of fibers include pulp fibers such as wood pulp fibers or annual plant fibers or synthetic staple fibers such as viscose and polylactic acid (PLA) fibers.
  • the fibers may be mono-component or multi-component, such as bi- component fibers.
  • Fibers as used herein may be fibers suitable for a process producing an absorbent web-based product in general and in particular for a tissue making process or a nonwoven making process.
  • the term “cellulosic fibers” also known as “wood pulp fibers”, “annual plant pulp fibers” or “non-wood fibers” characterizes fibers composed of or derived from cellulose.
  • Applicable wood pulps include chemical pulps, such as Kraft, sulfite, soda, and sulfate pulps, as well as mechanical pulps including, for example, groundwood, thermomechanical pulp and chemically modified thermomechanical pulp.
  • the term “manmade fiber” denotes a cellulosic or non-cellulosic, e.g., thermoplastic, fiber.
  • the term “manmade fibers” covers “synthetic fibers”, as well as “semi-synthetic fibers” made from natural sources such as rayon.
  • the term “hardwood fibers” as used herein refers to fibers derived from the woody substance of deciduous trees (angiosperms).
  • hardwood fibers are short fibers having an average length of from 0.5 mm to 2 mm, a diameter of from 15 to 30 ⁇ m, and a wall thickness of from 2 to 3 ⁇ m.
  • Hardwood fibers are usually pulped by the sulfite process or the kraft process.
  • the term “softwood fibers” as used herein refers to fibers derived from the woody substance of coniferous trees (gymnosperms).
  • the softwood fibers are “long” fibers having an average length of from 1.2 to 4 mm, a diameter of from 30 to 40 ⁇ m, and a wall thickness of from 3 to 4 ⁇ m.
  • Softwood fibers are usually pulped by the kraft process.
  • non-wood fibers refers to fibrous pulp derived from the non-woody substance of plants such as cotton, bagasse, hemp, miscanthus, sisal, straw, flax, or other plants.
  • natural cellulosic fibers as used herein may be understood in particular to cover seed hair fibers, e.g., cotton, kapok, or milkweed; leaf fibers, e.g., sisal, abaca, pineapple, or New Zealand hemp; and bast fibers, e.g., flax, hemp, jute, or kenaf.
  • the natural cellulosic fibers may originate from a plurality of natural sources" in addition to the fibers from waste such as bagasse and straw.
  • unrefined fibers characterizes fibers as naturally occurring or being obtained by their respective preparation process (chemical or mechanical pulping, recycling etc.). Although being dependent on the fiber source, unrefined hardwood pulp fibers and softwood pulp fibers typically have a Schopper Riegler freeness value of about 12 to 15 ⁇ SRV (wherein “SRV” stands for “Schopper Riegler (freeness) value”). Unrefined non-wood fibers pulp fibers (as coming from the pulp mill) can have a SR value in the range of 12 to 70 ⁇ SRV.
  • the term “refined fibers” as used herein characterizes to fibers which have been subjected to refining processes. Such processes are well known to those skilled in the art.
  • Refined fibers typically have a freeness value of more than 15 SRV to 75 SRV.
  • primary pulp fibers as used herein characterizes fibers as obtained from the pulping process of woody substances (e.g., hardwood, softwood) and non-woody substances (e.g., cotton, bagasse, hemp, miscanthus, etc.) which have not previously been used in a manufacturing process.
  • secondary pulp fibers as used herein characterizes fibers that have previously been used in a manufacturing process (e.g., paper- or tissue-making), and have been reclaimed (recycled) as raw material for the manufacturing method of the present disclosure.
  • Fiber length characterizes the average length weighted by length (Lpl) of fibers determined using a MorFi LB01 device (lab equipment) by TECHPAP. According to the test procedure, a pulp sample is treated with a macerating liquid to ensure that no fiber bundles or shives are present. Each pulp sample is disintegrated in hot water and diluted to an approximately 0.001 % solution. Individual test samples are drawn in approximately 50 to 100 ml portions from the dilute solution when tested using a standard MorFi fiber analysis test procedure.
  • the average length weighted by length (Lpl) of fibers may be expressed by the following equation: wherein, L is the length of a single fiber, and n is the total number of fibers measured.
  • the term “rheology modifier” as used herein characterizes a substance that is capable of modifying the viscosity, in particular to increase the viscosity, of the medium with which it is mixed. Examples of rheology modifiers include, but are not limited to, cellulose ethers such as hydroxyethyl cellulose (HEC) and sodium carboxymethyl cellulose (CMC), hydrophilic polymers such as polyvinyl alcohols and polyethylene oxides, and polyamides.
  • HEC hydroxyethyl cellulose
  • CMC sodium carboxymethyl cellulose
  • slipping agent characterizes a substance that can reduce the friction and tackiness of the fibrous foam during the preparing step and subsequence method steps.
  • slipping agents include, but are not limited to, polyhydric alcohols such as glycerol, ethylene glycol and propylene glycol, and polyether polyols.
  • the term “draining” as used herein refers to the reduction of liquid content, i.e., to drawing off liquid. In particular, it covers reducing a water content. Draining may also be referred to as deliquidization, and, when (mostly or only) water is drained, as dewatering.
  • draining in particular encompasses mechanical techniques of reducing a liquid content, as opposed to drying which is to be considered a form of thermal reduction of liquid content.
  • defiberizing refers to a process of separating a group or bundle of fibers into at least 65%, optionally 70%, or 75% of individual fibers. In particular, defiberizing involves mechanical techniques causing shear forces, such as hammermilling.
  • deflocculating refers to a process of deflocculating fibers in a slurry or a foam (a fibrous foam) from a flocculent state to convert them into individual fibers. It in particular comprises dispersing and/or maintaining in a dispersed state.
  • Deflocculating may in particular be promoted by adding deflocculants to a substance to be deflocculated such as electrolyte-sourcing liquids or powders such as sodium silicate, Darvan, Displex added in small amounts.
  • the deflocculants may impart electrical charges to conglomerates of particles in a flocculated state in order to create a repelling force between such particles that drives them apart.
  • hammermilling refers to a process of using a mill (also referred to as a hammermill) to shred and/or crush a substance or material into smaller pieces by repeated blow of little hammers.
  • a hammermill may comprise a drum (e.g., a steel drum) containing a vertical or horizontal rotating shaft or drum on which hammers are mounted.
  • the hammers are free to swing on the ends of a cross or fixed to the central rotor.
  • the rotor is spun at a high speed inside the drum while material is fed into a feed hopper.
  • the material is impacted by the hammer bars, defiberized, and expelled through screens in the drum of a selected size.
  • the term “refining” as used herein refers to a mechanical treatment of a material comprising fibers that changes the properties, in particular, of the fibers.
  • refining may comprise fibrillation which involves the exposure of fibrils to increase the surface area of the fibers, thereby improving fiber–fiber bonding.
  • Refining may be particularly useful for increasing of the strength of fiber-to-fiber bonds by increasing the surface area of the fibers and making the fibers more pliable to conform around each other. This may increase the bonding surface area and may lead to a denser end product.
  • headbox refers to a device that distributes (or is configured to distribute) a continuous flow of slurry (e.g., a suspension of solids in a fluid, such as water) and/or foam and/or fibrous foam to a machine, optionally, at a constant rate and/or constant velocities, or that retards (or is configured to retard) the rate of flow, as to a top-feed filter, or for eliminating by overflow some of the finest particles.
  • a headbox may in particular be a headbox tube bank apparatus that permits the flow of slurry therethrough.
  • the headbox may in particular progressively improve the uniformity, stability, cleanliness of slurry and may lower turbulences of the slurry during flow thereof through the headbox.
  • the term “cylinder mold former” as used herein refers to a forming device comprising a mesh-covered rotating cylinder partially immersed in a tank of fiber slurry, the rotating cylinder being disposed to rotate in a cylinder vat.
  • the mesh covering the rotating cylinder may comprise two wires of different mesh.
  • the inner-wire also referred to as a backing wire
  • the top wire is usually of around 35 of 80 mesh.
  • the rotating cylinder is configured to drain water through the wire cloth leaving a fibrous deposit behind on its surface.
  • a cylinder mold former may promote a random distribution of fibers and may promote high consistency. Cylinder mold diameters typically range up to around 2000 mm, and cylinder mould faces range up to around 5500 mm. A working speed may be in a range of around 100 to 400 m/min.
  • suction breast roll former as used herein characterizes a type of former for tissue- and paper machines.
  • the former includes a headbox to distribute the fiber suspension or the fibrous foam and to ensure a uniform fiber distribution in the planar fiber containing layer, a forming wire to receive the fiber suspension or the fibrous foam, to transport and to enable drainage, and a vacuum supported suction breast roll to initiate and control the web formation and web drainage.
  • suction breast roll former also included within the term “suction breast roll former” are other embodiments of former for tissue- and paper machines, e.g., breast roll former comprising a solid breast roll and any kind of former for fourdrinier paper machines and former comprising cylindrical sleeves or forming cylinders, e.g., former for cylinder papermaking machines, or suction forming cylinder former and the like.
  • positive displacement pump refers to a device that is configured to add energy to a fluid by applying force to a liquid with a mechanical device such as a piston or plunger.
  • a positive displacement pump may decrease a volume containing the liquid until the resulting liquid pressure equals the pressure in the discharge system. This way, the potential energy is increased.
  • the displacement pumps referred to herein, may be rotary pumps, blow cases, or reciprocating pumps, as well as combinations thereof.
  • the positive displacement pumps cover steam pumps, power pumps, controlled volume pumps, vane pumps, piston pumps, flexible member pumps, lobe pumps, gear pumps, circumferential piston pumps, and screw pumps. All percentages and ratios are calculated by weight unless otherwise indicated. 2.
  • the method comprises the step of preparing a fibrous foam.
  • the preparing may comprise supplying fibers, one or more surface active agents, a liquid, and a gas, wherein a fiber content is 5% to 60% by weight, a surface active agents content is 0.02% to 1.20% by weight, a liquid content is 40% to 95% by weight, and a gas content is 64% or more by volume.
  • the liquid may be water or it may comprise water.
  • the gas may be air or it may comprise air and other gases, such as nitrogen or carbon dioxide.
  • the fiber content, surface active agents content and liquid content are based on the total weight of the fibrous foam.
  • the gas content is based on the total volume of the fibrous foam.
  • the liquid and/or the foam, in which the surface active agents, the fibers, and the gas are dispersed, which is supplied for the preparing may comprise at least 80% by weight of water. It may comprise at least 85%, at least 87%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, or at least 95% by weight of water.
  • the gas, that is to be dispersed in the liquid and/or the foam may comprise at least 95% air by volume.
  • the gas liquid dispersion may have a liquid content of at least 80% by weight of water, and/or a gas content of at least 95% air by volume.
  • the liquid content may be at least 85%, at least 87%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, or at least 95% by weight of water.
  • a gas content of 64% or more, and, for example, an air content of 64% or more is where a jamming transition occurs between bubbly liquid and a wet foam (vol.% based on the total volume of the fibrous foam).
  • the fibrous foam may, hence, be a wet foam.
  • the fibrous foam may be a dry foam.
  • a dry foam may have a gas content of 95% or more.
  • a gas content of 64% or more provides the fibrous foam with appropriate properties, particularly in terms of rheology, thereby promoting homogeneous forming of the fibrous foam, as well as transporting.
  • a gas content of 64% or more may help to prevent fiber flocculation (despite a high fiber consistency) and may provide a relevant yield stress and stability to the fibrous foam.
  • the fibrous foam may be prepared to have a viscosity in the range of from 50 to 2000 Pa.s in accordance with the lower shear rate in the down-curve methodology at a shear rate of 0.01 s-1 (as described in section 2.f) below) and a storage modulus in the range of from 400 to 2500 Pa in the linear viscoelastic region (as described in section 2.f)).
  • the fibrous foam may then be formed into a foam layer with a viscosity in the range of from 50 to 3000 Pa.s in accordance with the lower shar rate in the down-curve methodology at a shear rate of 0.01 s-1 (as described in section 2.f)) and a storage modulus in the range of from 500 to 10000 Pa in the linear viscoelastic region (as described in section 2.f)).
  • the gas content of the fibrous foam may be 70% or more, 75% or more, or, in particular, 80% or more, 85% or more, 90% or more, or 92% or more (vol.% based on the total volume of the fibrous foam).
  • a fibrous foam with 80% gas content or more may be particularly suitable for the manufacturing method.
  • the prepared fibrous foam is stable.
  • the “foam stability” means the time that the foam will maintain its initial properties as generated, such as gas content and/or rheological properties. Foam stability may be expressed in terms of “half-life”, which is the time required for half of the volume of liquid contained in the foam to revert to the bulk- liquid phase.
  • the fibrous foam of the present disclosure may have a half-life of 2 min or more, or 3 min or more, or 4 min or more, or 5 min or more.
  • the half-life of the fibrous foam may be determined by (1) taking a sample of the fibrous foam and measuring its gas content to determine the liquid volume of the fibrous foam, (2) pouring 1L of the fibrous foam in a graduated cylinder and start the chronometer, (3) stopping the chronometer when half of the liquid volume is drained at the bottom of the graduated cylinder and reporting this time as the half-life of the fibrous foam.
  • the measurement is conducted in a conditioned laboratory (23°C, 50% relative humidity).
  • the foam or fibrous foam can be prepared by any method enabling gas entrapment in the liquid including, e.g., chemical foaming, injection of pressurized gas and/or mechanical mixing.
  • the foam or fibrous foam may be prepared by using, for example, a high consistency mixing apparatus.
  • Non-limiting examples of suitable mixing apparatuses include the Pico-mix (available from Hansa Industrie-Mixer GmbH, Germany) and the Lamort mixer (available from Kadant Inc.), or a paddle mixer (available from Forberg International AS).
  • the mixer may be run at a speed of 100 rpm or more, or 200 rpm or more, and 5000 rpm or less, or 2000 rpm or less, or 1000 rpm or less, in particular 600 rpm or less.
  • the viscosity can be determined using a Brookfield viscosimeter (operating conditions: V60 or V12, spindle 61).
  • the preparing may comprise supplying fibers.
  • the fibers may be supplied as substantially individual fibers as obtained by a suitable chemical- and/or mechanical pretreatment, such as a pre-treatment with a debonder for fluff pulp, or CMC, and/or hammermilling.
  • the supplied fibers may be dry or may be pretreated (e.g., pre-moisturized and/or fluff pretreated with CMC or another suitable agent) with a liquid (e.g., water) such that the liquid content of the fibers supplied is up to 80% by weight, or up to 60% by weight, such as about 40% by weight, based on the total weight of the (pretreated) fibers.
  • the preparing of the fibrous foam may comprise pre-moisturizing the fibers and mixing, optionally with a paddle mixer, until a solids content in the range of 30% to 50% by weight is reached, to form pre-moistened fibers, the solids content being based on the total weight of the pre-moistened fibers.
  • a fiber content may be 5% by weight or more, 10% by weight or more, 15% by weight or more, or 20% by weight or more, and 60% by weight or less, or 45% by weight or less, or 35% by weight or less, or 30% by weight or less, based on the total weight of the fibrous foam.
  • a fiber content of 5% by weight or more, particularly 10% by weight or more, or greater than 10% by weight promotes foam stability, homogenous formation and/or desirable product properties, such as basis weight and density.
  • a fiber content of 5% by weight or more results in a fibrous web that requires less draining (e.g., dewatering) and/or drying, thereby promoting energy efficiency of the manufacturing method.
  • a fiber content greater than 60% by weight may not be desirable as it may promote flocculation or cause jamming problems in the machine.
  • the supplied fibers may be natural and/or manmade fibers.
  • the fibers may comprise pulp fibers including, but not limited to, chemical pulp fibers, mechanical fibers that have undergone chemical pre-treatment, and mixtures thereof.
  • chemical pulp refers to a fibrous material obtained from plant raw materials from which most of the non-cellulosic components have been removed by chemical pulping without substantial mechanical post-treatment (in accordance with DIN 6730).
  • the supplied fibers may be only natural fibers or only manmade fibers.
  • the supplied fibers may only be cellulose based fibers, in order to produce a recyclable absorbent product. This may promote sustainability.
  • the “natural fibers” may be any wood fibers and/or non-wood fibers commonly used in papermaking.
  • the natural fibers may originate from a plurality of natural sources.
  • the fibers may be pulp fibers obtained by any suitable pulping process.
  • the pulp fibers may be obtained by, e.g., the kraft pulping process, the soda pulping process, the sulfite pulping process, the chemical pulping process, the chemi-mechanical pulping (CMP) process, the thermomechanical pulping (TMP) process, the chemi-thermomechanical pulping (CTMP) process, the bleached chemi-thermomechanical pulping (BCTMP) process, or the pressure/pressure thermomechanical pulping process (PTMP).
  • the pulp fibers may be bleached by using chlorine-free bleaching steps in view of the production of environmentally sound products and process steps.
  • the pulp fibers are obtained by the soda pulping process or the CTMP process as described, e.g., by Cappeltto et al.
  • the wood pulp fibers may be ground wood pulp fibers.
  • the wood pulp fibers may be selected from pulp fibers comprising hardwood fibers, such as eucalyptus, beech, aspen, acacia or birch fibers, and softwood fibers, such as pine, spruce, red cedar, Douglas fir, hemlock, or larch fibers.
  • Softwood fibers particularly useful in the present method are Northern Bleached Softwood Kraft (NBSK) fibers.
  • the wood pulp fibers may be a mixture of pulp fibers comprising hardwood and softwood fibers.
  • the weight ratio of hardwood fibers to softwood fibers may be from 80/20 to 0/100, or 50/50 to 0/100, or 30/70 to 0/100.
  • Softwood fibers may promote desirable strength and/or rheological properties, while hardwood fibers may contribute to achieving good softness.
  • the wood pulp fibers may be refined or may be unrefined. In one aspect, at least a part of the softwood fibers to be used are refined and/or at least a part of the hardwood fibers to be used are unrefined.
  • the softwood fibers may be refined to a degree of freeness of 19 to 35°SRV, in particular, 19 to 26°SRV, such as 19 to 24°SRV.
  • the hardwood pulp fibers originate from eucalyptus and/or the softwood pulp fibers are Northern Bleached Softwood Kraft (NBSK) fibers, wherein the NBSK fibers are optionally refined to a degree of freeness of 19 to 35°SRV, in particular 19 to 26°SRV, such as 19 to 24°SRV.
  • the non-wood fibers may be selected from cotton, bagasse, hemp, miscanthus, sisal, straw and flax fibers.
  • the non-wood fibers may be refined or may be unrefined.
  • the non-wood fibers may be bleached or unbleached.
  • the pulp fibers used in the present manufacturing method may be a primary fibrous material (e.g., soft-wood, hard-wood, or non- wood fibers such as straw or bagasse), a secondary fibrous material (i.e., a fibrous material comprising secondary pulp fibers), and mixtures thereof.
  • a primary fibrous material e.g., soft-wood, hard-wood, or non- wood fibers such as straw or bagasse
  • a secondary fibrous material i.e., a fibrous material comprising secondary pulp fibers
  • all fibers present in the tissue paper web are primary pulp fibers, or (ii) a mixture of primary and secondary (recycled) pulp fibers.
  • the manmade fibers may be cellulosic fibers and/or non- cellulosic fibers.
  • the manmade fibers may be any fibers used in the manufacture of substrates and formed by an appropriate technique such as spinning.
  • Cellulosic manmade fibers may be selected from: - regenerated cellulose, such as rayon, viscose, lyocell, acetate and other fibers derived from cellulose, and - modified fibers such as modified southern pine fibers (sold, for example, under the trade name Helix fibers).
  • Regenerated cellulose may be obtained by conversion of natural cellulose to a soluble cellulosic derivative and subsequent regeneration of the cellulose, typically forming fibers or filaments.
  • the use of the cellulosic manmade fibers contributes to the provision of a bio-based, sustainable product. Examples of regenerated cellulose suitable for the manufacturing process include but are not limited to Lyocell, Tencel, Newcell, Seacell, and Excel fibers.
  • the cellulosic manmade fibers have not been chemically modified.
  • Examples of cellulosic manmade fibers that have not been chemically modified include viscose and lyocell.
  • Use of cellulosic filaments formed of natural cellulose that has not been chemically modified further contributes to the provision of a plastic free product.
  • the manmade cellulosic fibers may comprise a plurality of fiber types.
  • Non-cellulosic manmade fibers may be selected from polyesters (e.g., polyalkylene terephthalate (PET), polybutylene terephthalate (PBT), (biobased) polylactic acid (PLA), polybutylene succinate (PBS), polybutylene succinate-co-adibate (PBSA), polyhydroxyalkanoates (PHA), and the like), polyolefins (e.g., polyethylene, polypropylene and the like), polyamides (e.g., nylons such as nylon-6, nylon-6,6, nylon 6,12 and the like), and polyacrylonitrile (PAN).
  • polyesters e.g., polyalkylene terephthalate (PET), polybutylene terephthalate (PBT), (biobased) polylactic acid (PLA), polybutylene succinate (PBS), polybutylene succinate-co-adibate (PBSA), polyhydroxyalkanoates (PHA), and the like
  • the supplied fibers may comprise multi- or bi- component fibers such as fibers having a core/sheath structure, e.g., fibers wherein the core is made of a first material and the sheath is made of another material.
  • a useful bicomponent fiber i.e., xylan-enriched viscose
  • Further useful fibers include, but are not limited to, polyethylene-polypropylene fibers.
  • Bicomponent fibers may be useful in order to improve the bonding between fibers.
  • the natural fibers may have an average fiber length of from 0.2 mm to 40 mm, or from 0.3 mm to 30 mm, or from 0.3 mm to 25 mm, or from 0.5 to 20 mm, or from 0.5 to 3 mm.
  • the manmade fibers may have any desirable average fiber length.
  • the manmade fibers may be prepared to have an average fiber length of from 0.2 mm to 50 mm, or from 0.5 mm to 30 mm, or from 1 mm to 25 mm.
  • the manmade fibers may be staple fibers, which are cut to a specific length for the manufacturing method of the present disclosure.
  • the staple fibers may be formed of polyethylene, polypropylene, polyester, (e.g., polylactide, polyhydroxyalkanoate), polyamide, or cellulose, preferably of polylactide, polyhydroxyalkanoate or cellulose, more preferably of cellulose.
  • the use of staple fibers formed of polylactide, polyhydroxyalkanoate or cellulose contributes to the provision of a biodegradable and compostable product.
  • the staple fibers may be formed of bio-based polyethylene, bio-based polypropylene, bio-based polyester, or bio-based polyamide.
  • the use of staple fibers formed of bio-based polyethylene, bio-based polypropylene, bio-based polyester, or bio-based polyamide contributes to the provision of a bio-based product.
  • the staple fibers may be formed of cellulose of natural origin, such as regenerated cellulose (as described above).
  • the use of staple fibers formed of cellulose of natural origin contributes to the provision of a bio-based, sustainable product.
  • the manmade staple fibers as used herein may have an average length of from 5 to 25 mm, or 5 to 20 mm.
  • the preparing step may, more generally, comprise supplying solids.
  • the solids comprise the fibers and may comprise further solids.
  • the further solids may be selected, for example, from fillers, pigments and other solid materials commonly used in absorbent products.
  • fillers examples include clay (or kaolin), calcined clay (or kaolin), ground calcium carbonate (GCC), precipitated calcium carbonate (PCC), titanium dioxide, satin white, zinc oxide, barium sulfate, gypsum, silica, alumina trihydrate, talc, mica and diatomaceous earth, and bio-fillers such as wood chips, saw dust, husk, etc.
  • a solids content may be 5% to 60% by weight based on the total weight of the fibrous foam, and at least 80% by weight of the solids may be fibers. At least 85%, or at least 90%, or at least 95%, 97%, 98%, 99%, or 99.5% by weight of the solids may be fibers.
  • the prepared fibrous foam may have a solids content of more than 10% by weight.
  • the prepared fibrous foam may have a fiber content of more than 10% by weight. This may offer a particularly beneficial consistency for an absorbent web-based product.
  • the solids content may, in particular, be more than 12% by weight.
  • the fiber content may, be more than 12% by weight.
  • the increased solids content (or fiber content) may offer a particularly beneficial consistency for an absorbent web-based product.
  • the solids content (or, in particular, the fiber content) may, in particular, be more than 14%, 16%, 17% 18%, 19%, 20%, 21%, 22%, 23%, 24%, or 25% by weight.
  • the increased solids content may offer a particularly beneficial consistency for an absorbent web-based product.
  • the preparing may comprise supplying one or more surface active agents.
  • the surface active agents are not particularly limited as long as they can be used to generate foam.
  • the surface active agent(s) may be selected from anionic surface active agents, cationic surface active agents, zwitterionic surface active agent(s), amphoteric surface active agents, and nonionic surface active agents.
  • the surface active agent(s) may be polymeric or protein-based.
  • the anionic surface active agent(s) may be selected from anionic sulfates, alkyl ether sulfonates, alkyl aryl sulfonates (e.g., (di)alkyl(di)benzene sulfonic acid, alkylphenol sulfonic acid, and the like), alkali metal sulforicinates, sulfonated glyceryl esters of fatty acids, salts of sulfonated monovalent alcohol esters, metal soaps of fatty acids, amides of amino sulfonic acids (e.g., 2-acrylamido-2-methylpropane sulfonic acid), sulfonated amides of amino sulfonic acids, sulfonated products of fatty acid nitriles, alkali metal alkyl sulfates (e.g., sodium dodecyl sulfate (SDS), sodium laurate, sodium laureth s
  • the cationic surface active agent(s) may be selected from fatty acid amines and amides and salts thereof (e.g., dodecyl amine acetate, tallow fatty acids acetate, dodecyl aniline, undecylimidazoline, and the like), mono-, di-, or tri-carbyl ammonium or phosphonium salts, carbylcarboxy salts, quaternary ammonium salts (e.g., dioctadecyldimethyl ammonium chloride, didodecyldimethyl ammonium chloride, dihexadecyl ammonium chloride, and the like), imidazolines, ethoxylated amines, quaternary phospholipids, and combinations thereof.
  • fatty acid amines and amides and salts thereof e.g., dodecyl amine acetate, tallow fatty acids acetate, dodecyl aniline, unde
  • the zwitterionic surface active agent(s) may be selected from betaines and mixtures thereof.
  • zwitterionic surface active agent(s) include, but are not limited to, cocodimethyl carboxymethyl betaine, cocoamidopropyl betaine, lauryl amidopropyl betaine, lauryl betaine, betaine citrate, sodium hydroxymethyl glycinate, carboxymethyl)dimethyl-3-[(1 - oxododecyl) amino] propylammonium hydroxide, coco alkyldimethyl betaines, (carboxymethyl) dimethyloleylammonium hydroxide, cocoamidopropyl betaine, (carboxylatomethyl) dimethyl(octadecyl)ammonium, and combinations thereof.
  • amphoteric surface active agent(s) may be selected from sodium acyl amphoacetates, sodium acyl amphopropionates, disodium acyl amphodiacetates and disodium acyl amphodipropionates where the alkanoyl group may comprise a C7- C18 alkyl portion.
  • amphoteric surfactants include, but are not limited to, sodium lauroamphoacetate, sodium cocoamphoacetate, sodium lauroamphoacetate, sodium cocoamphoacetate, and combinations thereof.
  • the nonionic surface active agent(s) may be selected from amine oxides, alkylglucosides, alkylpolyglucosides, polyhydroxy fatty acid amides, alkoxylated mono- and di-fatty acid esters, alkoxylated fatty alcohols, alkoxylated alkylphenols, fatty acid monoglycerides, polyoxyethylene sorbitan, sucrose esters, and combinations thereof.
  • the nonionic surface active agent(s) may be selected from alkylglucosides, alkylpolyglucosides, alkoxylated fatty alcohols, and combinations thereof.
  • the nonionic surface active agent(s) may have the following general formula (1): R 1-O-(R2)n-H (1) wherein, R 1 is a linear or branched hydrocarbon group having from 4 to 20 carbon atoms, R 2 is a hexose or pentose unit, and n is 1 to 5.
  • R 1 may be a linear or branched hydrocarbon group having from 6 to 18 carbon atoms, or from 8 to 16 carbon atoms, in particular 10 carbon atoms.
  • R 1 may a linear hydrocarbon group of formula –(CH 2 ) n’ -CH 3 wherein n’ is 3 to 19, or 5 to 17, or 7 to 15, in particular 9.
  • R 2 may be a hexose unit or may be a pentose unit.
  • n may be 1 to 4, in particular 1 or 2.
  • the nonionic surface active agent(s) may have the following general formula (2): C H3–(CH2)n’-O-(R2)n-H (2) wherein, R 2 is a hexose unit, and n is 1 or 2.
  • a particularly suitable alkylpolyglucoside is Simulsol SL10 (available from Seppic, France).
  • a surface active agents content may be from 0.02% to 1.20% by weight based on the total weight of the fibrous foam.
  • the surface active agents content may be from 0.05% to 1.0% by weight, or from 0.1% to 0.8% by weight, or from 0.2% to 0.7% by weight.
  • a content of less than 0.02% by weight may not produce a foam with adequate gas (e.g., air) content and/or stability, while a content of more than 1.20% by weight may not be cost effective.
  • the preparing of the fibrous foam may comprise supplying at least one nonionic surface active agent or a mixture of surface active agents comprising at least one nonionic surface active agent.
  • the preparing may comprise supplying only one or more nonionic surface active agents.
  • the at least one nonionic surface active agent(s) may be selected from the group consisting of amine oxides, alkylglucosides, alkylpolyglucosides, polyhydroxy fatty acid amides, alkoxylated mono- and di-fatty acid esters, alkoxylated fatty alcohols, alkoxylated alkylphenols, fatty acid monoglycerides, polyoxyethylene sorbitan, and sucrose esters.
  • the at least one nonionic surface active agent may be selected from alkylglucosides, alkylpolyglucosides, and alkoxylated fatty alcohols.
  • the at least one nonionic surface active agent may have the above general formula (1), or the above general formula (2).
  • the at least one nonionic surface active agent may be comprised in an amount of at least 50% by weight, or at least 75% by weight, or at least 90% by weight, or at least 95% by weight based on the total weight of the mixture.
  • the liquid may comprise at least 80% by weight of water. Alternatively, the liquid may comprise at least 85%, 90%, 96%, 97%, 98%, 99%, 99.5%, or at least 99.8% by weight of water. The use of significant amounts of water as the liquid may promote cost efficiency.
  • the liquid may also comprise a polar solvent except water, in particular an alcohol, such as ethyl alcohol or isopropyl alcohol.
  • Such a polar solvent may be comprised in an amount of 10% by weight or less, in particular 5% by weight or less based on the total weight of the liquid supplied.
  • the liquid may comprise further components including one or more binders, one or more rheological modifiers, and other additives, which are soluble therein.
  • the gas may comprise at least 95% air by volume. Alternatively, the gas may comprise at least 96%, 97%, 98%, 99%, 99.5%, 99.8%, or at least 99.9% of air by volume. The use of significant amounts of air as the gas may promote cost efficiency.
  • the gas may comprise nitrogen and/or carbon dioxide.
  • the gas may also be a mixture of air with nitrogen and/or carbon dioxide, wherein the mixture optionally comprises at least 10% air by volume, or at least 50% air by volume, or at least 90% air by volume.
  • the use of nitrogen and/or carbon dioxide as the gas may promote foam stability.
  • the preparing may comprise supplying one or more binders.
  • the use of one or more binders may be advantageous for stabilizing the porous structure and/or improving the strength properties of the absorbent product.
  • the binder(s) that may be used in the manufacturing method are not particularly limited and may be selected from, for example, strength resins commonly used in papermaking. In one aspect, the binder(s) may be selected from wet strength agents and dry strength agents.
  • the wet strength agent(s) may be selected from urea-formaldehyde (UF) resins, melamine-formaldehyde (MF) resins, polyethylene imines, polyvinylamines, polyureide-formaldehyde resins, glyoxal-acrylamide resins and cationic materials obtained by the reaction of polyalkylene polyamines with polysaccharides such as starch and various natural gums, as well as 3-hydroxyazetidinium ion-containing resins, which are obtained by reacting nitrogen- containing polymers with epichlorohydrine. Suitable materials are described in further detail in US 3,998,690 and EP 1583 869 B1.
  • the wet strength agent(s) may be selected from polyaminoamide-epichlorohydrine resins, polyamide-epichlorihydrin (PAE) resins, polyamine- epichlorohydrine resins and aminopolymer-epichlorohydrine resins. Examples of these resins are the commonly used Kymene resins (available from Ashland).
  • the dry strength agent(s) may be selected from polycarboxylic acids and anhydrides such as starch-based polymers, (meth)acrylic acid-derived polymers and copolymers, modified polyacrylamides, saccharides, polyvinyl alcohols, copolymers derived from maleic anhydride, vinyl copolymers of carboxylic acids and cellulose-based polymers.
  • Cellulose ethers in particular carboxyalkylated polysaccharides and carboxyalkylated cellulose derivatives, are especially suitable for use in the present method.
  • the cellulose ethers include carboxymethyl cellulose (CMC), methyl cellulose (MC), hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), methyl ethyl cellulose (MEC), hydroxyethylmethyl cellulose (HEMC), hydroxypropylmethyl cellulose (HPMC) guar, locust bean gum, carboxymethyl starch and the like, and their alkali metal salts or ammonium salts.
  • Sodium carboxymethyl cellulose (CMC) is particularly suitable for the present method.
  • the binder(s), e.g., polysaccharides such as CMC and modified starches, may also be capable of modifying the rheological properties, in particular to increase the viscosity, of the fibrous foam.
  • the binder(s) may be used alone or in combination with one or more other rheology modifiers (described further below).
  • the fibrous foam comprises one or more binders (e.g., CMC) and is substantially free of other rheology modifiers.
  • the term “substantially free” means that other rheology modifiers are not supplied or supplied such that their content is less than 0.05% by weight, or less than 0.02% by weight, based on the total weight of the fibrous foam.
  • the content of the binder(s) as described above, if present, may be from 0.005 to 30% by weight, or from 0.01 to 28% by weight, or from 0.05 to 25% by weight, or from 0.10 to 20% by weight, or from 0.10 to 15% by weight based on the total weight of the fibers supplied.
  • the binder(s) may be selected from latexes such as anionic styrene-butadiene copolymers, anionic styrene­butadiene copolymers, polyvinyl acetate homopolymers, vinyl-acetate ethylene copolymers, vinyl­acetate acrylic copolymers, ethylene- vinyl chloride copolymers, ethylene-vinyl chloride-vinyl acetate terpolymers, acrylic polyvinyl chloride polymers, acrylic polymers, nitrile polymers, and combinations thereof.
  • latexes such as anionic styrene-butadiene copolymers, anionic styrene­butadiene copolymers, polyvinyl acetate homopolymers, vinyl-acetate ethylene copolymers, vinyl­acetate acrylic copolymers, ethylene- vinyl chloride copolymers, ethylene-vinyl chloride-vinyl acetate terpolymers, acrylic polyvin
  • the content of the latex(es), if present, may be from 5.0 to 20.0% by weight, or from 10.0 to 15.0% by weight, based on the total weight of the fibers supplied.
  • the binder(s) may be selected from microfibrillated cellulose (MFC) fibers, nanofibrillated cellulose (NFC) fibers, and mixtures thereof.
  • MFC microfibrillated cellulose
  • NFC nanofibrillated cellulose
  • the use of MFC and/or NFC fibers as a binder may promote desirable strength and haptic properties.
  • the content of the MFC/NFC fibers, if present, may be from 0.5 to 20.0% by weight, or from 0.8 to 10.0% by weight, or from 1.0 to 5.0% by weight, based on the total weight of the fibers supplied.
  • the preparing may comprise supplying one or more rheology modifiers.
  • the rheology modifier(s) may be particularly useful in order to defiberize the fibrous material and/or achieve desirable rheological properties for forming.
  • the rheology modifier(s) may be selected from water-soluble substances commonly used in papermaking including, but not limited to, cellulose ethers such as hydroxyethyl cellulose (HEC) and sodium carboxymethyl cellulose, hydrophilic polymers such as polyvinyl alcohols and polyethylene oxides, polyamides, and combinations thereof.
  • HEC hydroxyethyl cellulose
  • hydrophilic polymers such as polyvinyl alcohols and polyethylene oxides, polyamides, and combinations thereof.
  • water soluble means that a solubility in water at 25°C of at least 40g/l, or at least 200g/l, in particular 500g/l.
  • the supplied one or more rheology modifiers have a viscosity of from 10 to 2500000 cP, or from 100 to 140000 cP, or from 200 to 12000 cP, or from 300 to 6500 cP, or from 700 to 3000 cp, or from 750 to 2500 cP, or from 800 to 2000 cP, or from 800 to 1500 cP (as measured using a Brookfield viscosimeter and a 1% solution in water at 25°C).
  • the content of the rheology modifier(s), if present, may be from 0.001 to 10 % by weight, or from 0.001 to 5 % by weight, or from 0.001 to 2 % by weight, or from 0.001 to 1 % by weight, or from 0.001 to 0.5 % by weight, or from 0.001 to 0.25 % by weight, or from 0.001 to 0.15 % by weight, or from 0.001 to 0.1 % by weight, or from 0.001 to 0.05 % by weight based on the total weight of the fibers supplied.
  • the preparing may comprise supplying one or more slipping agents.
  • the slipping agent(s) may be advantageous to reduce the friction and tackiness of the fibrous foam in the preparing and subsequent method steps.
  • the slipping agent(s) may be selected from polyhydric alcohols such as glycerol, ethylene glycol and propylene glycol, polyether polyols, and combinations thereof.
  • the slipping agent (s) may be a polyether polyol selected from polyethylene glycol, polypropylene glycol, and combinations thereof.
  • the slipping agent (s) may be polyethylene glycol having, optionally, a number-average molecular weight of from 100 to 1000000, or from 500 to 500000, or from 800 to 250000, or from 1000 to 20000, or from 1500 to 10000 as determined by a suitable technique, such as Gel Permeation Chromatography (GPC).
  • GPC Gel Permeation Chromatography
  • the content of the slipping agent(s), if present, may be from 0.001 to 10 % by weight, or from 0.001 to 5 % by weight, or from 0.001 to 2 % by weight, or from 0.001 to 1 % by weight, or from 0.001 to 0.75 % by weight, or from 0.001 to 0.5 % by weight, or from 0.001 to 0.3 % by weight, or from 0.001 to 0.2 % by weight, or from 0.001 to 0.15% by weight, or from 0.001 to 0.10% by weight based on the total weight of the fibers supplied.
  • the preparing may comprise supplying one or more additives.
  • the additives may be selected from softeners, debonders, retention agents, expanding microcapsules (e.g., Expancel microspheres) pH modifiers, colorants, dyes and the like.
  • the additive(s) are soluble and/or dispersible in the liquid and distinguished from the solids described above.
  • the content of the additive(s), if present, may be from 0.001 to 0.5 % by weight, from 0.001 to 0.3 % by weight, from 0.001 to 0.2 % by weight, or from 0.005 to 0.18% by weight, or from 0.01 to 0.15% by weight, or from 0.01 to 0.10% by weight based on the total weight of the fibers supplied.
  • the method includes the step of preparing a fibrous foam comprising fibers, a liquid, and a gas, wherein a fiber volume fraction is 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or less, or 0.005 or less.
  • the liquid may be water, or it may comprise water.
  • the gas may be air, or it may comprise air.
  • the prepared fibrous foam may, more generally, comprise solids, and a solids volume fraction may be 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or less, or 0.005 or less.
  • At least 80% by weight of the solids may be fibers.
  • At least 85%, or at least 90%, or at least 95%, 97%, 98%, 99%, or 99.5% by weight of the solids may be fibers.
  • All of the solids may be fibers.
  • a fiber content may be from 5% to 60% by weight.
  • a liquid content may be from 40% to 95% by weight.
  • a gas content may be 64% or more by volume, optionally at least 70%, at least 75%, or at least 80%, by volume.
  • the preparing may comprise supplying a rheology modifier.
  • the rheology modifier may be used to decrease or increase the viscosity of the fibrous foam and may promote stability.
  • the method may comprise, prior to the step of preparing the fibrous foam, a step of preparing a liquid slurry comprising at least one component selected from the group consisting of: liquid, e.g., water, fibers, a surface active agent, a binder, and a slipping agent.
  • the preparing of the fibrous foam may comprise supplying at least one surface active agent or a mixture of surface active agents.
  • any one or several of the surface active agents or types of surface active agents defined in this disclosure may be supplied.
  • the surface active agent(s) may be selected from anionic surface active agents, cationic surface active agents, amphoteric surface active agents, zwitterionic surface active agents, and nonionic surface active agents.
  • the preparing of the fibrous foam may comprise supplying at least one nonionic surface active agent or a mixture of surface active agents comprising at least one nonionic surface active agent, the nonionic surface active agent(s) being optionally selected from the group consisting of amine oxides, alkylglucosides, alkylpolyglucosides, polyhydroxy fatty acid amides, alkoxylated mono- and di-fatty acid esters, alkoxylated fatty alcohols, alkoxylated alkylphenols, fatty acid monoglycerides, polyoxyethylene sorbitan, and sucrose esters.
  • the nonionic surface active agent(s) being optionally selected from the group consisting of amine oxides, alkylglucosides, alkylpolyglucosides, polyhydroxy fatty acid amides, alkoxylated mono- and di-fatty acid esters, alkoxylated fatty alcohols, alkoxylated alkylphenols, fatty acid monoglycerides, polyoxyethylene
  • the at least one nonionic surface active agent may be selected from the group consisting of alkylglucosides, alkylpolyglucosides, and alkoxylated fatty alcohols, the at least one nonionic surface active agent being optionally an alkylpolyglucoside of the general formula (1): R 1-O-(R2)n-H (1) wherein, R 1 is a linear or branched hydrocarbon group having from 4 to 20 carbon atoms, R 2 is a hexose or pentose unit, and n is 1 to 5.
  • the preparing of the fibrous foam and transporting the fibrous foam to the foam layer formation means may be promoted by the same mechanical movement. This may particularly promote process efficiency and/or allow lowering the specific energy consumption.
  • the method may comprise a step of forming the fibrous foam into a foam layer.
  • the forming into a foam layer may in particular involve bringing the fibrous foam into a planar form.
  • a foam layer has two dimensions of extension (two directions of a planar surface) and a dimension of thickness, wherein the foam layer is thin in the dimension of thickness as compared to the dimensions of planar extension.
  • the form of a foam layer may be beneficial in terms of allowing draining, in particular, mechanical draining, but also allowing thermal drying.
  • the foam layer may be considered a step towards the desired form of an absorbent web-based product that is the base material of hygiene products such as tissue paper-like products or non-woven products.
  • the forming of the fibrous foam into a foam layer may comprise bringing the fibrous foam into a planar layer.
  • the planar form may allow for an efficient draining (in particular, for a dewatering).
  • the method may comprise bringing one or several of a liquid slurry, a foam, solids, liquid, and the fibrous foam into contact with at least one rotatable means, such as a screw, and rotating the at least one rotatable means to transport the fibrous foam.
  • the rotating of the at least one rotatable means e.g., a screw
  • the rotating of the at least one rotatable means may effect the mechanical draining / dewatering or it may contribute to the draining / dewatering.
  • the rotating of the at least one rotatable means may also process the fibrous foam or contribute to processing the fibrous foam.
  • the at least one rotatable means may be rotated with from 100 to 5000 revolutions per minute, or with 500 to 3000 revolutions per minute, or 800 to 2800 revolutions per minute, or 1000 to 2500 revolutions per minute, or 1600 to 2400 revolutions per minute.
  • the rotatable means may be comprised by a high shear mixer, and the speed at which the mixer is run may be 100 rpm or more.
  • the speed may be 200 rpm or more and 5000 rpm or less, or 200 rpm or more and 2000 rpm or less, or 200 rpm or more and 1000 rpm or less, or 200 rpm or more and 600 rpm or less.
  • the forming of the fibrous foam into the foam layer may be at least in part performed in one or several of the following devices: a die, a headbox, and a cylinder mold former.
  • the die may be a slot die with an adjustable die gap.
  • the fibrous foam may be processed into a continuous fibrous web or sheet on a moving continuous dewatering/conveyor unit.
  • the forming the fibrous foam into the foam layer may comprise bringing the fibrous foam into a planar form.
  • a planar form is a form in which one dimension of the foam (orthogonal to the plane of the planar form) is much thinner than the dimension in the planar directions.
  • the forming means that performs the forming may comprise at least one foam shaping part (a flow part) over which a fibrous foam flows, in order to be brought into a planar form.
  • a die and/or a headbox and/or a cylindrical mold may have an outlet opening with a cross-section perpendicular to a flow direction of the fibrous foam and having a long axis, which may also be referred to herein as a width of the outlet opening, and a short axis, which may also defined herein as a height of the outlet opening, wherein a ratio between a long axis dimension and a ratio between a short axis dimension is in a range of 2 or more, 4 or more, 6 or more, 8 or more, or 9 or more, or 10 or more, or 11, or 12, or 13 or more.
  • the forming means may comprise two or more foam shaping parts.
  • the short axis of the outlet opening of the forming means may have a dimension of at least 0.5 mm, or at least 0.8 mm, 0.9 mm, or 1.0 mm. These minimum short axis dimensions, to an increasing degree with increasing minimum value, may be suitable to prevent or even avoid clogging.
  • the outlet short axis (referred to as a height in particular in the case in which the short axis is oriented in the direction of gravity or substantively in the direction of gravity) may be a slit opening.
  • the outlet short axis dimension may be in a range from 0.5 mm to 5.0 mm, from 0.8 mm to 4.0 mm, from 0.9 mm to 3.0 mm, or from 1.0 mm to 2.5 mm
  • the forming means may comprise an inlet defined by a width of a cross-section perpendicular to a flow direction of the fibrous foam and having a long axis, which may also be referred to herein as a width of the outlet opening, and a short axis, which may also be defined herein as a height of the opening.
  • the long axis of the inlet opening may be at least 1.5, 2.0, 3.0, 5.0, or 8.0 times larger than the short axis of the outlet opening.
  • the outlet height may be adapted to a desired foam consistency.
  • the foam consistency, the fiber volume fraction, and/or the air content may be adapted to achieve a desired target basis weight and/or density of the product.
  • the solids volume fraction in general, and, in particular, the fiber volume fraction may be tailored to the desired basis weight and/or density.
  • the forming means may comprise a lateral spread-out part that is shaped as to promote a lateral spreading out of foam, in order to increase the ratio of the MD/CD dimension of the foam.
  • the forming means may comprise or consist of a die and/or a headbox and/or a cylindrical mold.
  • the forming means may comprise or consist of a plurality of dies or headboxes or cylinder mold formers (or combinations thereof).
  • the forming of the fibrous foam into the foam layer may be fully performed in the forming means, and in particular, e.g., in one or several die(s) and/or one or several headbox(es).
  • Draining (in particular: dewatering) and drying The method may comprise a step of draining the fibrous foam in the foam layer to form a fibrous web, wherein the fibrous web has a liquid content of 20% to 85% by weight.
  • the liquid content of 20% to 85% of the fibrous web may be considered a remarkably low liquid content as a starting point for a subsequent drying step.
  • the liquid content at the end of the draining step may be half of the liquid content encountered in comparable manufacturing methods prior to a drying step. This may allow saving up to 80%, in particular at least 50% of the energy that will be needed to appropriately dry the product during a subsequent drying step.
  • the liquid content of the fibrous web may be 20% to 85% by weight, or 25% to 85% by weight, or 30% to 80% by weight, or 40% to 80% by weight, or 50% to 80% by weight, or 50% to 75% by weight.
  • the draining of the fibrous foam may comprise mechanical draining. Mechanical draining relies on the use of mechanical force to remove liquid.
  • the mechanical draining can also be referred to as mechanical dewatering.
  • the mechanical draining may be intensified by increasing a temperature of the liquid prior to the mechanical draining.
  • the mechanical draining may allow for a reduction of liquid content and, hence, for lowering a specific energy consumption during thermal draining (in particular, thermal dewatering), i.e., for reducing the specific energy consumption. This may promote energy savings and, hence, promote environment friendliness.
  • the dewatering of the fibrous foam may comprise mechanical dewatering. Mechanical dewatering relies on the use of mechanical force to remove water.
  • the draining of the fibrous foam may consist of mechanical draining.
  • the dewatering may consist of mechanical dewatering.
  • the dewatering is in this context be understood not to comprise drying, i.e., the dewatering is in this context to be considered separate from thermal draining (in particular, thermal dewatering) in the sense of drying.
  • the method may comprise a drying step of drying the fibrous web to obtain an absorbent web-based product.
  • the specific energy consumption for the drying may be lowered as compared to when relying on conventional manufacturing processes.
  • One of the reasons may lie in the significantly lower liquid content of the fibrous web as compared to known intermediate products.
  • the drying may bring down the liquid content to the level needed for an absorbent product.
  • the drying may comprise thermal drying.
  • the drying may comprise freeze drying.
  • the drying may comprise infrared drying.
  • the drying may comprise contact drying.
  • the drying may comprise impingement drying.
  • the drying may comprise microwave drying.
  • the drying may comprise through air drying.
  • the drying may comprise any combination of the mentioned types of drying and repeated steps of drying.
  • the drying may, in particular, be considered thermal drying, as opposed to mechanical draining.
  • the step of drying may be performed and the absorbent web-based product obtained may have a liquid content of 0.5% to 15% by weight.
  • the liquid content may be 1% to 15% by weight.
  • the liquid content may be 1% to 10% by weight.
  • the liquid content may be 1.5% to 8% by weight.
  • the liquid content may be 1.8% to 6.5% by weight.
  • the liquid content may be 2% to 5% by weight.
  • the increasingly narrower ranges of liquid contents may be increasingly beneficial for the absorbent properties of the absorbent web-based product combined with a sufficient stability and customer satisfaction with hygiene products comprising the absorbent web-based product.
  • the absorbent web-based product may have a water content of 1% to 15% by weight.
  • the water content may, in particular, be 1% to 10% by weight.
  • the water content may, in particular, be 1.5% to 8% by weight.
  • the water content may, in particular, be 1.8% to 6.5% by weight.
  • the water content may, in particular, be 2% to 5% by weight.
  • the draining may comprise applying a vacuum to the foam layer with a constant pressure or with a varying pressure.
  • the variation may be a temporal or a spatial variation.
  • the pressure may be increased or lowered as a function of time.
  • the pressure may be higher or lower up- and downstream (i.e., a spatial pressure variation).
  • the varying pressure may be a pressure that has at least one decrease in a downstream direction of transportation.
  • the pressure may, e.g., be successively decreased and increased, re- decreased, etc.
  • the draining may be performed by successively applying at least two stages of vacuum to the foam layer, optionally, with an decreasing pressure. In-between these stages, the pressure may or may not be lowered. In other words, there may be several stages of increasing and decreasing the pressure.
  • the preparing step may comprise processing a liquid slurry or a foam and fibers into the fibrous foam.
  • a liquid slurry and solids, such as fibers, or a foam and solids, such as fibers may be processed into the fibrous foam.
  • the processing may at least partially be performed by a transporting means that transports the fibrous foam to a forming means that forms the fibrous foam into the foam layer.
  • a transporting means that transports the fibrous foam to a forming means that forms the fibrous foam into the foam layer.
  • the processing may be performed by the transporting means. This may particularly promote being able to perform the manufacturing in a space-efficient manner.
  • Uniting processing and transporting allows for an integral carrying out of the steps, for example, with a single structural unit. This may in turn also allow for higher processing speeds, as the same procedural step may promote both processing as well as transportation. The fusing of those steps may also lower the specific energy consumption, as the same movements may be used to promote different aims in parallel.
  • the apparatus may comprise a pressurization device between the transportation means and the forming means.
  • the processing may be performed by a processing means and the draining of the fibrous foam may be performed by a draining means.
  • One or several of the following components may be part of one integral structural unit: the processing means, the transporting means, the forming means, and the draining means.
  • the integral structural unit may comprise any two or any three or all of the listed means.
  • the increasing of pressure may be effected by changing the speed of transportation (e.g., by subsequently increasing and lowering the transportation velocity, or vice versa).
  • the increasing or decreasing of the pressure may, e.g., be an increase or a decrease by at least 0.1 bar. It may be up to 10 bars. It may be in a range of 0.5 bar to 8 bar.
  • the pressure may be increased once or several times.
  • the pressure may be decreased once or several times.
  • the pressure may be increased and decreased once or several times.
  • the pressure increases and/or decreases may contribute to changing the properties of the foam being processed.
  • the processing may comprise successively applying a plurality of different pressure levels in the downstream direction, wherein the pressure level may be decreased twice or more and/or the pressure level may be increased twice or more.
  • the increasing of the pressure may comprise successively applying a plurality of different pressure levels in the downstream direction, the pressure levels being increased at least twice.
  • the processing may comprise at least one of: heating, defiberizing, deflocculating, refining, dispersing, disintegrating, changing fiber shapes, and adding chemical additives. The above may be achieved by exerting shear forces, elongational forces, and mixing, in particular by exerting elongational forces.
  • the fiber volume fraction in the fibrous foam may be controlled in particular by choosing a consistency of one or several types of fibers in the fibrous foam and the air content in the fibrous foam. Adjusting the fiber volume fraction may be used to control properties of the fibrous foam, such as the viscosity and/or the rheology.
  • the processing may in particular be used to decrease the fiber volume fraction. Alternatively, the processing may be carried out such that the fiber volume fraction stays more or less the same. Alternatively, the processing may be carried out to increase the fiber volume fraction.
  • the rotating of the at least one rotatable means may promote defiberizing at least a part, optionally all of the fibers. This may be a particularly efficient use of energy to promote transportation and to at the same time also promote defiberizing. This may further promote energy-efficiency.
  • the fibrous foam may be transported through at least one processing device selected from the following list: an industrial mixer, a screw kneader, an industrial kneading machine, an extruder, a mono- or twin-screw machine, a mono- or twin-screw continuous kneader, a twin-screw or multiple-screw machine, a conical screw mixer, comprising the at least one rotatable means.
  • an industrial mixer a screw kneader, an industrial kneading machine, an extruder, a mono- or twin-screw machine, a mono- or twin-screw continuous kneader, a twin-screw or multiple-screw machine, a conical screw mixer, comprising the at least one rotatable means.
  • the method may comprise supplying to the fibrous foam, when transporting the fibrous foam through the processing device, at least one component selected from the following list: - a liquid, such as water, optionally comprising one or more additives; - a gas, such as air; - a foam and/or a liquid slurry; and - a solid, such as fibers, powder, and/or granulate.
  • the liquid may, e.g., be derived from dispersing an additive in a medium.
  • the one or more additives may comprise additive solution, liquid additives, and/or additive dispersion.
  • the rotating of the at least one rotatable means comprises rotating a twin-screw, a single-screw, or a multiple-screw.
  • the transporting of the fibrous foam by rotating the at least one rotatable means may comprise one or several of the following: accelerating the fibrous foam; decelerating the fibrous foam; and applying a shear force to the fibrous foam.
  • the application of a shear force (or of different shear forces), and/or the accelerating or decelerating of the foam, may contribute to modifying foam properties, such as, in particular, viscosity and/or rheology.
  • the rotating of the at least one rotatable means is performed in a screw assembly.
  • the screw assembly may comprise a housing and the at least one screw (as an example of a rotatable means).
  • a minimum distance, in a cross-section of the at least one screw perpendicular to a rotational axis, between the at least one screw and an opposing inner surface of the housing is in the range of from 1% to 20% of an outer diameter of the screw, optionally in the range of from 0.3 mm to 20 mm.
  • the outer diameter of the screw, at a particular position of the screw along its rotational axis, is to be understood to be the diameter of the surface that is swept by a section of the rotating screw in a direction perpendicular to the rotational axis. This outer diameter of the screw may also be referred to as the flight diameter, the major diameter, or the diameter of a surface of revolution of the screw.
  • the outer diameter of the screw may vary along the direction of its rotational axis or it may remain constant.
  • An example of a screw with a varying outer diameter is a conical screw.
  • the minimum distance referred to, is the minimum distance amongst all minimum distances at different positions along the rotational axis of a screw.
  • the outer diameter of the screw may be in a range of from 1.5 mm to 2000 mm, or from 2 mm to 1500 mm, or from 4 mm to 1000 mm, or from 5 mm to 800 mm, or from 8 mm to 700 mm, or from 12 mm to 500 mm, or from 15 mm to 400 mm, or from 18 mm to 350 mm, or from 20 mm to 300 mm, or from 20 mm to 250 mm, or from 20 mm to 200 mm, or from 20 mm to 150 mm, or from 20 mm to 120 mm, or from 20 mm to 110 mm, or from 20 mm to 100 mm.
  • the at least one rotatable means may comprise at least a first screw and a second screw.
  • the first screw and the second screw may be independently rotatable, or rotatable together, or, in some embodiments, alternatively independently or commonly rotatable.
  • a distance of closest approach between the first screw and the second screw during rotations may be in the range of from 0.3 mm to 20 mm.
  • the distance of closest approach may be in a range of from 0.35 mm to 20 mm, or from 0.4 mm to 15 mm, or from 0.45 mm to 12 mm, or from 0.5 mm to 10 mm, or from 0.7 mm to 7 mm, or from 0.8 mm to 5 mm, or from 0.9 mm to 3 mm, or from 0.93 mm to 2 mm, or from 0.95 mm to 1.5 mm.
  • the first screw and the second screw may be intermeshing or they may be non-intermeshing.
  • the outer diameter of the first screw may be constant along its rotational axis or it may vary along the rotational axis.
  • the closest approach between the first screw and the housing may be constant or it may vary along the rotational axis.
  • the outer diameter of the second screw may be constant along its rotational axis or it may vary along the rotational axis.
  • the closest approach between the second screw and the housing may be constant or it may vary along the rotational axis.
  • the term closest approach between a screw and the housing refers to the distance between a sweeping surface of the outer diameter of the respective screw and the opposing surface of the housing.
  • the distance of closest approach refers to the smallest distance amongst all the distances along the respective rotational axis.
  • the term closest approach between two screws refers to the minimum distance between the two screws reached when the screws are being rotated.
  • the at least one rotatable means may comprise a plurality of screws and at least one housing that houses the plurality of screws.
  • a distance of closest approach between any screw amongst the plurality of screws and an opposing inner surface of the at least one housing that houses the any screw may be in the range of from 0.3 mm to 20 mm.
  • the distance of closest approach may be in a range of from 0.35 mm to 20 mm, or from 0.4 mm to 15 mm, or from 0.45 mm to 12 mm, or from 0.5 mm to 10 mm, or from 0.7 mm to 7 mm, or from 0.8 mm to 5 mm, or from 0.9 mm to 3 mm, or from 0.93 mm to 2 mm, or from 0.95 mm to 1.5 mm.
  • the fibrous foam Prior to the forming, the fibrous foam may be displaced by a displacement pump.
  • the fibrous foam may also be displaced by two or more displacement pumps, in particular positive displacement pumps.
  • Each of the displacement pumps (or, if there is a single one, the one displacement pump) may be a of rotary or of reciprocating type.
  • a positive displacement pump may develop high pressures while operating at low suction pressures.
  • the displacement by one or several displacement pumps may be combined with other types of displacement.
  • the method may be controlled may, to this end, comprise one or several control units.
  • the dispersing of the gas in the liquid may be performed using a feedback loop control.
  • the feedback loop control may include measuring at least one of a gas content, a density of a gas-liquid dispersion, and a conductivity of a gas-liquid dispersion, and adding and dispersing gas until at least one of the gas content, the density, and the conductivity reaches a target value.
  • the feedback loop control may include measuring and controlling one, two, or three of the mentioned parameters.
  • the feedback loop control may include measuring and controlling one or several different parameters.
  • the target value for the gas content may be set in a range of 70% or more by volume, or 75%, or 80%, or 85%, or 90% or more by volume of the gas-liquid dispersion.
  • the target value for the density may be set to be in a range of from 3 to 550 kg/m 3 , or from 4 to 355 kg/m 3 , or from 5 to 300 kg/m 3 , or from 6 to 180 kg/m 3 , or from 7 to 150 kg/m 3 , or from 7 to 130 kg/m 3 , or from 8 to 110 kg/m 3 , or from 9 to 90 kg/m 3 , or from 9.5 to 75 kg/m 3 .
  • the target value for the conductivity may be set in a range of 0 to 5000 ⁇ S/cm, or 100 to 4000 ⁇ S/cm, or 500 to 3500 ⁇ S/cm, or 1000 to 3000 ⁇ S/cm.
  • the preparing may comprise supplying the gas and the liquid into a vessel such that a volume ratio between the amount of liquid supplied and the amount of gas supplied lies in a predetermined range or amounts to a predetermined value.
  • the predetermined volume ratio may be in a range of from 0.002 to 0.55, or from 0.005 to 0.43, or from 0.01 to 0.33, or from 0.018 to 0.25, or from 0.025 to 0.18, or from 0.033 to 0.14.
  • the preparing may comprise supplying the gas and the liquid into a vessel such that a density of the gas-liquid dispersion lies in a predetermined range or amounts to a predetermined value.
  • the predetermined range may be set to be in a range of from 3 to 550 kg/m 3 , or from 4 to 355 kg/m 3 , or from 5 to 300 kg/m 3 , or from 6 to 180 kg/m 3 , or from 7 to 150 kg/m 3 , or from 7 to 130 kg/m 3 , or from 8 to 110 kg/m 3 , or from 9 to 90 kg/m 3 , or from 9.5 to 75 kg/m 3 .
  • the preparing may comprise mechanically mixing in the vessel for at least a predetermined amount of time or until a foam parameter, such as a foam height and/or a gas content reaches a predetermined minimum threshold.
  • the predetermined minimum threshold for the foam heigh may be set in accordance with the geometry of the fibrous foam preparation means.
  • the predetermined minimum threshold for the gas content may be set to be at least 70%, or 75%, 80%, or 85%, or 90%, or 93%, or 95%, or 96% by volume.
  • Creping is a treatment method that may be applied to a ply of web-based absorbent material, in order to create a ripping, three-dimensional texture. Creping may comprise the use of a Yankee cylinder (a Yankee drier) steam heated rotating pressure vessel.
  • a Yankee cylinder may comprise a steam heated rotating pressure vessel, (e.g., rotating with a circumference speed of between 1 and 50 m/s, or from 2 to 45 m/s, or from 5 to 45 m/s, or from 10 to 40 m/s, or from 20 to 35 m/s, and, e.g., with a diameter of between 0.5 to 8 m, optionally 0.7 to 6 m, or 0.8 to 5 m, or 1 to 4 m, or 1 to 3 m in diameter and slightly wider than a full width of a ply of web-based absorbent material to be creped.
  • a steam heated rotating pressure vessel e.g., rotating with a circumference speed of between 1 and 50 m/s, or from 2 to 45 m/s, or from 5 to 45 m/s, or from 10 to 40 m/s, or from 20 to 35 m/s, and, e.g., with a diameter of between 0.5 to 8 m, optionally 0.7 to
  • a crepe blade (also sometimes referred to as a fixed doctor blade) that extends in a width direction of the Yankee cylinder in the creping position may be used as a mechanical component that is used to impart creping.
  • a zone between the crepe blade tip and the Yankee surface where creping takes place may be referred to as a crepe pocket.
  • An alternative or additional process for a structure modification process when manufacturing a web-based absorbent material is the rush transfer applied at web transfer from a surface to another one, e.g., from draining permeable conveyor to drying permeable conveyor.
  • the structural change is caused by a speed difference of the surfaces causing either a compression and network deformation in case the second surface is moved with a lower speed then the first surface or a network stretching in case the second surface is moved with a higher speed then the first surface.
  • the surface structure of the second surface may be fully or partially imprinted into a surface of the web-based absorbent material.
  • the transfer may be supported by the application of vacuum, either for ensuring a successful transfer of the material from the first surface to the second surface, and/or to intensify the structure modification.
  • the rush transfer may be applied at any transfer within the process when manufacturing a web-based absorbent material and can be applied within a wide range of solids content.
  • the manufacturing of the end product may in particular comprise web handling.
  • the manufacturing of the end product may comprise winding up a manufactured absorbent web-based product.
  • the manufacturing of the end product may comprise confectioning a manufactured absorbent web-based product, on its own, or combined with one or several further products. Confectioning may comprise any one or several of the following operations which may be considered part of a tissue converting process, such as folding, laminating, printing, coating, embossing.
  • the manufacturing of the end product may comprise converting a manufactured absorbent web-based product into a packaged or an unpackaged end product.
  • a packaged end product may, e.g., comprise or consist of a product that has been packaged in a plastic wrapping or packaging, or in another type of wrapping or packaging.
  • the end product may be a consumer end product, or it may be a retailer or distributor product.
  • the end product may be a multipack of products. Moreover, the end product may comprise or consists of packaged or unpackaged single absorbent web-based product plies or of a multi-ply product comprising at least one manufactured absorbent web-based product ply.
  • An end product may be a multi-ply product comprising one or several manufactured absorbent web-based product ply, wherein two or more plies of the multi-ply product may be identical or mutually different.
  • the single ply or multi-ply end product may be rolled, or folded, or stacked, stapled, or grouped in another way. 3.
  • Absorbent web-based product This disclosure also relates to an absorbent web-based product that is manufacturable by the method in accordance with one or several of the aspects of the method described above.
  • An aspect may be one or several features and, in particular, a combination of features as discussed.
  • this disclosure also relates to an absorbent web-based product that is manufactured by the method in accordance with one or several of the aspects of the method described above.
  • the manufacturable absorbent web-based product may have a basis weight of 500g/m2 or less, or 300g/m2 or less, or 200g/m2 or less, or 150g/m2 or less, or 10 to 120 g/m and a density of 5 to 200kg/m3, or 8 to 150kg/m3, or 10 to 100kg/m, or 10 to 70 kg/m.
  • a variation ⁇ of the basis weight measured in accordance with SCAN-P 92:09 may be less than 20%, less than 15%, less than 10%, less than 5%, less than 3%, or less than 2% of the mean basis weight of the absorbent web-based product.
  • the variation ⁇ of the basis weight can be determined by beta- formation analysis.
  • the beta-formation analysis principle is based on the decay of the C-atom, emitting electron, antineutrino and resulting nitrogen (N). Briefly, the test sample is placed on top of a radiation source ( C, activity 1.18 GBq), and electrons penetrating the test sample are measured with an imaging plate (BAS IP-MS 2325). This is possible as the energy of the electrons is continuous from 0 to decay maximum energy Emax. The measured current of the electrons is the lower, the more there is material between the radiation source and imaging plate.
  • the radiation map of the electrons in the imaging plate is read with reader (BAS 1800 II 4046) and converted to basis weight map with Matlab. The result is a small-scale basis weight map of the sample. The pixel size is 1mm*1mm.
  • the absorbent web-based product may comprise at least 70 wt.-% of fiber material based on the total weight of the absorbent web-based product.
  • the absorbent web-based product may have a basis weight of 5g/m or more, or 8g/m or more, or 10g/m or more, and 500g/m2 or less, or 300g/m2 or less, or 200g/m2 or less, or 150g/m2 or less, or 10 to 120 g/m and a density of 5 to 200kg/m3, or 8 to 150kg/m3, or 10 to 100kg/m, or 10 to 70 kg/m.
  • the basis weight is in this context determined by the standard DIN/ISO 12625-6. This may in particular provide sufficient strength for the product that in turn provides the basis for a sufficient strength for a user end product, e.g., a hygiene product.
  • a variation ⁇ of the basis weight measured in accordance with SCAN-P 92:09 may be less than 20%, less than 15%, less than 10%, less than 5%, less than 3%, or less than 2% of the mean basis weight of the absorbent web-based product.
  • the absorbent web-based product may comprise one ply having a basis weight of 5g/m or more, or 8g/m or more, or 10g/m or more, and 500g/m2 or less, or 300g/m2 or less, or 200g/m2 or less, or 150g/m2 or less, or 120 g/m or less, or it may comprise more than one ply (e.g., two, three, four, five, or six plies) each having have a basis weight of 5g/m or more, or 8g/m or more, or 10g/m or more, and 500g/m2 or less, or 300g/m2 or less, or 200g/m2 or less, or 150g/m2 or less, or 10 to 120 g/m, optionally 10 to 100 g/m, and a density of 5 to 200kg/m3, or 8 to 150kg/m3, or 10 to 100kg/m, or 10 to 70 kg/m.
  • the absorbent web-based product may be a single-ply product or a multi-ply product that is tailored to the end user’s needs by further converting steps.
  • the absorbent web-based product may have an upper side and a lower side, and a density in a central region of the absorbent web-based product located between the upper and lower sides in a thickness direction may be lower than a density in a region of the absorbent web-based product located at the lower and/or upper side(s).
  • the absorbent web-based product may comprise a surface active agent. The presence of the surface active agent may allow verifying whether the product has been manufactured in accordance with some of the embodiments of the method of the present disclosure.
  • the absorbent web-based product may comprise one, two, or three of the following: (a) at least 0.2 wt.-% of one or more binders, (b) at least 0.05 wt.-% of one or more rheology modifiers, (c) at least 0.01 wt.-% of one or more surface active agents, and (d) at least 0.2 wt.-% of one or more slipping agents, each based on the total weight of the absorbent web-based product.
  • the remainder may comprise or consist of fibers.
  • the present disclosure also relates to a multi- ply product, e.g., a product comprising two.
  • the multi-ply product may further comprise at least one non-woven ply and/or at least one tissue paper ply, optionally a conventional wet press paper ply and/or a structured ply and/or a textured ply.
  • the present disclosure relates to a multi- ply product, e.g., a product comprising two, three, four, five or six plies, which comprises at least one ply that is made of an absorbent web-based product having a basis weight of 5g/m or more, or 8g/m or more, or 10g/m or more, and 500g/m2 or less, or 300g/m2 or less, or 200g/m2 or less, or 150g/m2 or less, or 10 to 120 g/m and a density of 5 to 200kg/m3, or 8 to 150kg/m3, or 10 to 100kg/m, or 10 to 70 kg/m.
  • a multi- ply product e.g., a product comprising two, three, four, five or six plies, which comprises at least one ply that is made of an absorbent web-based product having a basis weight of 5g/m or more, or 8g/m or more, or 10g/m or more, and 500g/m2 or
  • the multi-ply product may further comprise at least one non-woven ply and/or at least one tissue paper ply, optionally a conventional wet press paper ply and/or a structured ply and/or a textured ply.
  • the multi-ply product may be a product selected from the group consisting of wipes, sanitary products such as toilet paper, paper handkerchiefs, household towels, towels, tissues for facial use (facial tissues), napkins/serviettes, bed linens, and garments. 4.
  • Apparatus for manufacturing an absorbent web-based product This disclosure also relates to an apparatus for manufacturing an absorbent web-based product.
  • Fibrous foam preparation means The apparatus may comprise a fibrous foam preparation means preparing a fibrous foam.
  • the fibrous foam preparation means may comprise a supply means that supplies (or is configured to supply) fibers, one or more surface active agents, a liquid, and gas, wherein a fiber content is 5% to 60% by weight, a surface active agents content is 0.02% to 1.20% by weight, a liquid content is 40% to 80% by weight, and a gas content is 64% or more by volume.
  • the liquid may be water or it may comprise water.
  • the gas may be air or it may comprise air.
  • the supply means may supply (or be configured to supply) liquid comprising at least 80% water by weight, and/or gas comprising at least 95% air by volume.
  • the fibrous foam preparation means may comprise a solids supply means that supplies solids, wherein a solids content may be 5% to 60% by weight, and wherein at least 80% by weight of the solids may be fibers. At least 85%, or at least 90%, or at least 95%, 97%, 98%, 99%, or 99.5% by weight of the solids may be fibers. All of the solids may be fibers.
  • the fibrous foam preparation means may prepare (or may be configured to prepare) the fibrous foam with a solids content, wherein a solids volume fraction may be 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or less, or 0.005 or less, and wherein at least 80% of the solids content may be a fiber content.
  • the liquid may comprise at least 80% by weight of water. Alternatively, the liquid may comprise at least 85%, 90%, 93%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.8%, or at least 99.9% by weight of water. The use of significant amounts of water as the liquid may promote cost efficiency.
  • a fiber content may be 5% to 60% by weight.
  • a liquid content may be 40% to 95% by weight.
  • a gas content may be 64% or more by volume, optionally at least 70%, at least 75%, or at least 80%, by volume.
  • the gas may comprise at least 95% air by volume.
  • the gas may comprise at least 96%, 97%, 98%, 99%, 99.5%, 99.8%, or at least 99.9% of air by volume.
  • the use of significant amounts of air as the gas may promote cost efficiency.
  • the fibrous foam preparation means may prepare (or be configured to prepare) the fibrous foam with fibers, a liquid, and gas, and with a fiber volume fraction of 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or less, or 0.005 or less.
  • the liquid may be water or it may comprise water.
  • the gas may be air or it may comprise air.
  • the apparatus may comprise a liquid slurry preparation device that prepares (that is configured to prepare) an intermediate mixture/slurry foam/slurry solution comprising at least one component selected from the group consisting of: liquid, such as water, fibers, one or more surface active agents, one or more binders, and one or more slipping agents.
  • the apparatus may comprise a surface active agent supply means that supplies (or is configured to supply) at least one surface active agent or a mixture of surface active agents.
  • the surface active agent(s) may be selected from anionic surface active agents, cationic surface active agents, amphoteric surface active agents, zwitterionic surface active agents, and nonionic surface active agents.
  • the fibrous foam preparation means may transport (or be configured to transport) the fibrous foam to the forming means.
  • the fibrous foam preparation means may promote (or may be configured to promote) preparing of the fibrous foam and transporting the fibrous foam to the foam layer formation means by the same mechanical movement. This may particularly promote process efficiency and/or allow lowering the specific energy consumption.
  • the apparatus may comprise a high consistency mixing apparatus.
  • the high consistency mixing apparatus may be comprised by the transporting means and may be a part of the same structural unit as the transporting means, the processing means, and/or the fibrous foam formation means.
  • 4.2 Fibrous foam formation means The apparatus may comprise a foam layer formation means forming (or configured to form) the fibrous foam into a foam layer.
  • the foam layer formation means may bring (or be configured to bring) the fibrous foam into a planar form.
  • a foam layer has two dimensions of extension (two directions of a planar surface) and a dimension of thickness, wherein the foam layer is thin in the dimension of thickness as compared to the dimensions of planar extension.
  • the form of a foam layer may be beneficial in terms of allowing draining, in particular, mechanical draining, but also allowing (thermal) drying.
  • the foam layer may be considered a step towards the desired form of an absorbent web-based product that is the ground material of hygiene products such as tissue paper-like products.
  • the foam layer formation means may bring (or be configured to bring) the fibrous foam into a planar layer.
  • the planar form may allow for an efficient draining (in particular, for a dewatering).
  • the bringing the fibrous foam into a planar layer may alternatively also be referred to as forming the fibrous foam into a planar layer.
  • the apparatus may comprise a die and/or a headbox and/or a cylindrical mold that may at least in part perform (or be configured to perform) the forming.
  • the die and/or headbox may comprise at least one foam shaping part (a flow part) over which a fibrous foam flows, in order to be brought into a planar form.
  • a die and/or a headbox and/or a cylindrical mold may be shaped as to bring the foam into a form with a ratio of 8 or more between a length in the MD (machine direction) direction and a length in the CD direction (cross machine direction).
  • the ratio may be 2 or more, 4 or more, 6 or more, 9 or more, or 10 or more, or 11, or 12, or 13 or more.
  • the die and/or headbox may comprise two or more foam shaping parts.
  • the die and/or headbox may comprise an outlet height of at least 0.5 mm, or at least 0.8 mm, 0.9 mm, or 1.0 mm. These minimum heights, to an increasing degree with increasing minimum height, may be suitable to prevent or even avoid clogging.
  • the outlet height may be a slit opening.
  • the outlet height may be in a range from 0.5 mm to 5.0 mm, from 0.8 mm to 4.0 mm, from 0.9 mm to 3.0 mm, or from 1.0 mm to 2.5 mm
  • An inlet height may be at least 1.5, 2.0, 3.0, 5.0, or 8.0 times larger than the outlet height.
  • the outlet height, or, more generally, the opening size (e.g., a size of an outlet surface cross-section) may be adapted to a desired foam consistency or product.
  • the foam consistency, the fiber volume fraction, and/or the air content may be adapted to achieve a desired target basis weight of the foam layer.
  • the solids volume fraction in general, and, in particular, the fiber volume fraction may be tailored to the desired basis weight and/or density.
  • the die and/or headbox may comprise a lateral spread-out part that is shaped as to promote a lateral spreading out of foam, in order to increase the ratio of the MD/CD dimension of the foam.
  • Draining means e.g., dewatering means
  • the apparatus may comprise a draining means draining (or configured to drain) the fibrous foam in the foam layer to form a fibrous web having a liquid content of 20% to 85% by weight.
  • the liquid content of 20% to 85% of the fibrous web may be considered a remarkably low liquid content as a starting point for a drying means to subsequently perform a drying process.
  • the apparatus may have a lower specific energy consumption, as compared to an apparatus used in the course of conventional hygiene paper making processes.
  • the liquid content at the end of the draining step may be half of the liquid content encountered in comparable manufacturing methods prior to a drying step. This may allow using less energy as compared to a comparable manufacturing apparatus relying on conventional wet paper manufacturing.
  • the draining means may comprise a mechanical draining means. Mechanical draining relies on the use of mechanical force to remove liquid. When the liquid is or comprises water (or substantially water), the mechanical draining can also be referred to as mechanical dewatering.
  • the draining means may be a dewatering means.
  • the mechanical draining means may be a mechanical dewatering means. Mechanical dewatering relies on the use of mechanical force to remove water.
  • the mechanical draining may allow for a reduction of liquid content and, hence, promote the apparatus having a lower specific energy consumption, in particular associated with the thermal drying (in particular, thermal dewatering). This may promote energy savings and, hence, promote environment friendliness.
  • the draining means may consist of a mechanical draining means. It may comprise or consist of a mechanical dewatering means.
  • the dewatering is in this context be understood not to comprise drying, i.e., the dewatering is in this context to be considered separate from thermal draining (in particular, thermal dewatering) in the sense of drying.
  • the draining means may apply (or be configured to apply) a vacuum to the foam layer with a constant pressure or with a varying pressure. The variation may be a temporal or a spatial variation.
  • the pressure may be increased or lowered as a function of time.
  • the pressure may be higher or lower up- and downstream (i.e., a spatial pressure variation).
  • the draining means may comprise or consist of one or several vacuum boxes.
  • the varying pressure may be a pressure that has at least one decrease in a downstream direction of transportation.
  • the pressure may, e.g., be successively decreased and increased, re- decreased, etc.
  • the draining may successively apply (or be configured to successively apply), in some cases together with a control means, at least two stages of vacuum to the foam layer, optionally, with a decreasing pressure. In-between these stages, the pressure may or may not be increased. In other words, there may be several stages of decreasing and increasing the pressure.
  • the draining means may apply (or be configured to apply) a vacuum to the foam layer with a constant pressure or with a varying pressure, wherein the varying pressure is, optionally, a pressure that has at least one decrease in a downstream direction of transportation.
  • the draining means may apply (or be configured to apply) successive pressure decreases and/or increases, re- decreases, etc.
  • the apparatus may comprise a drying means that dries (or is configured to dry) the fibrous web to obtain an absorbent web- based product.
  • the specific energy consumption associated with subsequent drying may be lower than when using conventional manufacturing processes. This in turn may be associated with lower liquid contents of the fibrous web as compared to known intermediate products. Moreover, the drying may bring down the liquid content to the level needed for an absorbent product.
  • the drying means may comprise or consist of a thermal drying means.
  • the drying means may comprise or consist of a freeze drying means.
  • the drying means may comprise or consist of an infrared drying means.
  • the drying means may comprise or consist of a contact drying means.
  • the drying means may comprise or consist of an impingement drying means.
  • the drying means may comprise or consist of a microwave drying means.
  • the drying means may comprise or consist of a through air drying (TAD) drying means.
  • TAD through air drying
  • the drying means may comprise or consists of any combination of the mentioned types of drying means (including one or several drying means of a particular type).
  • the drying means may, in particular, be considered a thermal drying means, as opposed to a mechanical draining means.
  • the drying means may perform (or be configured to perform) the drying, and the absorbent web-based product obtained may have a liquid content of 0.5% to 15% by weight.
  • the liquid content may be 1% to 15% by weight.
  • the liquid content may be 1% to 10% by weight or 1.5% to 8% by weight.
  • the liquid content may be 1.8% to 6.5% by weight.
  • the liquid content may be 2% to 5% by weight.
  • the increasingly narrower ranges of liquid contents may be increasingly beneficial for achieving sufficient stability and customer satisfaction with hygiene products comprising the absorbent web-based product.
  • the absorbent web-based product may have a water content of 1% to 15% by weight.
  • the water content may, in particular, be 1% to 10% by weight or 1.5% to 8% by weight.
  • the water content may, in particular, be 1.8% to 6.5% by weight.
  • the water content may, in particular, be 2% to 5% by weight.
  • the fibrous foam preparation means may comprise a processing means that processes (or is configured to process) a liquid slurry and/or a foam and fibers into the fibrous foam.
  • the fibrous foam preparation means may comprise two or several processing means, wherein at least one of them may prepare a liquid slurry and/or a foam and another one of them may process (or be configured to process) a liquid slurry and/or the foam and fibers into the fibrous foam.
  • the fibrous foam preparation means may comprise two or several processing means, wherein at least one of them may process (or be configured to process) a liquid slurry and fibers into the fibrous foam and another one of them may process (or be configured to process) a foam and fibers into the fibrous foam.
  • the apparatus may further comprise one or several solids supply means supplying solids to the fibrous foam preparation means, and one or several liquid supply means supplying liquid to the fibrous foam preparation means, to form the fibrous foam with a solids content of 5% to 60% by weight of the fibrous foam, optionally of more than 10% by weight of the fibrous foam, and a liquid content of 40% to 95% by weight of the fibrous foam.
  • the one or several liquid supply means may supply liquid at different stages of the preparing, i.e., sequentially at different points in time or space during the preparing process.
  • the solids supply means and the liquid supply means may respectfully be dimensioned (and, in particular, relatively dimensioned) such that a fibrous foam with the desired (rheological) properties is obtained.
  • the apparatus may be provided with one or several control means that are configured to control the solids supply means and the liquid supply means such that a fibrous foam with the desired (rheological) properties is obtained.
  • the one or several control means may be configured to control a gas supply means, such as, e.g., an air supply means.
  • the fibrous foam preparation means may comprise a rheology modifier supply means that supplies (or is configured to supply) a rheology modifier.
  • the rheology modifier(s) may be particularly useful in order to defiberize the fibrous material and/or achieve desirable rheological properties for forming.
  • the fibrous foam preparation means may prepare (or may be configured to prepare) the fibrous foam to have a solids content of more than 10% by weight.
  • the solids content may in particular involve a fiber content, and the fiber content may be more than 10% by weight (of the fibrous foam).
  • the apparatus may comprise at least one rotatable means, and the apparatus may bring (or be configured to bring) one or several of a liquid slurry, a foam, solids, liquid, and the fibrous foam into contact with the at least one rotatable means and rotate (or be configured to rotate) the at least one rotatable means to transport the fibrous foam.
  • the rotating of the at least one rotatable means may also process the fibrous foam or contribute to processing the fibrous foam.
  • the same mechanical movement may be used particularly efficiently, as both transportation as well as processing and/or forming may be promoted by the same movements.
  • the apparatus may rotate (or be configured to rotate) the at least one rotatable means with from 100 to 5000 revolutions per minute, or with 500 to 3000 revolutions per minute, or 800 to 2800 revolutions per minute, or 1000 to 2500 revolutions per minute, or 1600 to 2400 revolutions per minute.
  • the rotatable means may be comprised by a high shear mixer, and the speed at which the mixer is run may be 100 rpm or more. The speed may be 200 rpm or more and 5000 rpm or less, or 200 rpm or more and 2000 rpm or less, or 200 rpm or more and 1000 rpm or less, or 200 rpm or more and 600 rpm or less.
  • the rotating of the at least one screw may promote at least one of the following: transporting, mixing, defiberizing, exerting pressure on, and building up pressure on the fibrous foam.
  • the apparatus may comprise at least one processing device selected from the following list: an industrial mixer, a screw kneader, an industrial kneading machine, an extruder, a mono- or twin-screw machine, a mono- or twin-screw continuous kneader, a twin-screw or multiple-screw machine, a conical screw mixer, comprising the at least one rotatable means.
  • the apparatus may comprise a screw mixer.
  • the screw mixer may, for example, be a conical screw mixer.
  • the screw mixer may in particular by a transportation means, as described above.
  • the screw mixer may, e.g., comprise the at least rotating means (in this case: a screw).
  • the apparatus may comprise a fully automated foam generator that may produce foams, e.g., with densities between 50 and 1000 g/l. It may comprise a temperature controlled mixing head and may comprise a double action mechanical seal. It may further also be PLC-controlled with an automated air volume control and, e.g., a touchscreen.
  • the screw mixer may, e.g., comprise an (e.g., gasket free) eccentric screw pump, e.g., with a temperature controlled storage tank.
  • the apparatus may comprise a supply means that supplies (or is configured to supply), while the fibrous foam is transported through the processing device, at least one component selected from the following list: - a liquid, such as water, optionally comprising one or more additives; - a gas, such as air; - a foam and/or a liquid slurry; and - a solid, such as fibers, powder and/or granulate.
  • the at least one rotating means may be a twin screw, a single screw, or a multiple screw.
  • the at least one rotating means may comprise one or several of the following sections: an acceleration section that accelerates (or is configured to accelerate) the fibrous foam being transported through the transporting means, such as, for example, an extruder, a mixer, or a kneader; a deceleration section that decelerates (or is configured to decelerate) the fibrous foam being transported through the transporting means; a shear and/or elongation application section that applies (or is configured to apply) a shear and/or elongation force to the fibrous foam.
  • the apparatus may comprise a screw assembly that comprises a housing and the at least one rotatable means.
  • a distance of closest between the at least one rotating means and an opposing inner surface of the housing may be in the range of 0.3 mm to 20 mm, or from 0.4 mm to 15 mm, or from 0.45 mm to 12 mm, or from 0.5 mm to 10 mm, or from 0.7 mm to 7 mm, or from 0.8 mm to 5 mm, or from 0.9 mm to 3 mm, or from 0.93 mm to 2 mm, or from 0.95 mm to 1.5 mm.
  • the apparatus may comprise a displacement pump.
  • the displacement pump may, for example, be a rotary lobe pump, a progressing cavity pump, a rotary gear pump, a piston pump, a diaphragm pump, a screw pump, a gear pump, a hydraulic pump, a rotary vane pump, a peristaltic pump, a rope pump, a flexible impeller pump, and the like, that, prior to the forming, displaces (or is configured to displace) the fibrous foam.
  • the displacement pump may be comprised by a transportation means, as described above.
  • the processing means may be provided in a controlled pressure chamber.
  • the foam layer formation means may be provided in a controlled pressure chamber.
  • the processing means and the foam layer formation means may be provided in the same controlled pressure chamber or in different controlled pressure chambers.
  • the apparatus may comprise a transporting means that transports (or is configured to transport) the liquid slurry and/or the foam and/or the fibrous foam and/or solids, such as fibers, to the foam layer formation means.
  • the processing means may comprise the transporting means, and the transporting means may perform at least a part of the processing.
  • the transporting means may perform the processing.
  • the processing means and the transporting means may be one and the same structural unit. Uniting the transporting and the processing, or, more generally, the transporting and the foam formation, at least partially or even fully, may promote space efficiency of the machinery needed for the manufacturing process.
  • uniting the different steps and performing them in integral multi-purpose devices may also promote processing speed (as one and the same step may at the same time promote more than one processing step) and may promote being able to lower the specific energy consumption.
  • One or several of the following components may be part of one integral structural unit: the processing means, the fibrous foam preparation means, the transporting means, the forming means, a heating means, and the draining means.
  • two of the listed components may be a single unit, i.e., a structurally integral unit.
  • any three of the listed components or all four of them may be a single unit, i.e., a structurally integral unit. This may allow for a particularly space-saving construction of the apparatus.
  • the transporting means may comprise a pressurization section that increases (or is configured to increase) a pressure applied to the liquid slurry or the fibrous foam during the transporting by the transporting means in a downstream direction of transportation.
  • the increasing of pressure may be effected by changing the speed of transportation (e.g., by subsequently increasing and lowering the transportation velocity, or vice versa).
  • the pressurization section may increase (or be configured to increase) the pressure applied to the liquid slurry or the fibrous foam during transporting at least twice and/or decrease (or be configured to decrease) the pressure applied to the liquid slurry or the fibrous foam during transporting at least twice.
  • the increasing or decreasing of the pressure may, e.g., be an increase or a decrease of at least 0.1 bar.
  • the pressure may be increased several times.
  • the pressure may be lowered once or several times.
  • the pressure may be increased and decreased several times.
  • the pressure increases and/or decreases may contribute to changing the properties of the foam being processed.
  • the fibrous foam may comprise compressible compounds, as well as non-compressible compounds.
  • the variations in pressure may change the fiber volume fraction of the fibrous foam and, hence, have an impact on its rheology.
  • the pressurization section may successively apply (or be configured to successively apply) a plurality of different pressure levels in the downstream direction, the pressure levels being increased at least twice.
  • the processing (or transporting) means may perform (or may be configured to perform) at least one of the following: exerting shear forces, mixing, defiberizing, deflocculating, refining, dispersing, disintegrating, changing fiber shapes, heating the slurry to improve subsequent drainage, and adding chemical additives. Any one or several of the listed types of processing may be used to adjust and control properties of the fibrous foam, such as the viscosity and/or the rheology.
  • the fibrous foam may be prepared to have a viscosity in the range of from 50 to 2000 Pa.s measured in accordance with the down- curve methodology at a shear rate of 0.01s (as described in section 2.f) below) and a storage modulus in the range of from 400 to 2500 Pa in the linear viscoelastic region (as described in section 2.f)).
  • the fibrous foam may then be formed into a foam layer with a viscosity in the range of from 50 to 3000 Pa.s measured in accordance with the down-curve methodology at a shear rate of 0.01s (as described in section 2.f) below) and a storage modulus in the range of from 500 to 10000 Pa in the linear viscoelastic region (as described in section 2.f)).
  • the processing may in particular be used to lower the fiber volume fraction. Alternatively, the processing may be carried out such that the fiber volume fraction stays more or less the same. Alternatively, the processing may be carried out to increase the fiber volume fraction.
  • Control means The apparatus may comprise a temperature control means that controls (or is configured to control) a temperature inside at least one section of the apparatus.
  • the apparatus may comprise a control device that controls (or is configured to control) the apparatus to perform the method in accordance with any one or several of the above-discussed method steps.
  • Manufacturing apparatus for end product This disclosure also relates to an apparatus for manufacturing an end product.
  • the apparatus for manufacturing an end product may comprise an apparatus for manufacturing an absorbent web- based product in accordance with any one or several of the aspects discussed above.
  • the apparatus for manufacturing an end product may comprise any one or several of the following components: a web handling device, a winding device, a confectioning device, and a conversion device that converts into a packaged or unpackaged end product.
  • a web handling device a winding device, a confectioning device, and a conversion device that converts into a packaged or unpackaged end product.
  • Fig. 1A is a schematic view of an apparatus for manufacturing an absorbent web-based product in accordance with an embodiment of the present disclosure
  • Fig. 1B is schematic view of an embodiment of an apparatus for manufacturing an absorbent web-based product in accordance with an embodiment of the present disclosure
  • Fig. 2 depicts an exemplary fibrous foam preparation means
  • Fig. 3A depicts a perspective view of a part of exemplary foam layer formation means
  • FIG. 3B depicts the part of the exemplary foam layer formation means of Fig. 3A without an upper part of the cover so that a part of the inside is visible;
  • Fig. 3C depicts a sectional side view of a die, as an example of a foam layer formation means;
  • Fig. 4A depicts a sectional view of a twin-screw pump as an example of a transportation means of an apparatus for manufacturing a web-based absorbent product in accordance with the present disclosure;
  • Fig. 4B depicts a sectional view of a lobe pump as an example of a transportation means of an apparatus for manufacturing a web-based absorbent product in accordance with the present disclosure;
  • FIG. 5A is a perspective view of an extruder, as an example of a transportation means of an apparatus for manufacturing a web-based absorbent product in accordance with the present disclosure
  • Fig. 5B depicts the extruder of Fig. 5A, but with a part of the housing removed, to expose the interior
  • Fig. 6A depicts a part of a double screw of an extruder
  • Fig. 6B depicts a part of a double screw of an extruder exposed from its housing
  • Fig. 6C shows a sectional view of the double screw of Figs. 6A and 6B together with its housing
  • Fig. 7A depicts a part of another embodiment of an extruder comprising multiple screws located inside of their common housing
  • FIG. 7B depicts a part of an embodiment of an extruder comprising multiple screws located inside of their common housing 31;
  • Fig. 8 depicts a draining means of an apparatus for manufacturing a web-based absorbent product in accordance with the present disclosure that is used when carrying out embodiments of a method in accordance with the present disclosure;
  • Fig. 9 depicts a drying means of an apparatus for manufacturing a web-based absorbent product in accordance with the present disclosure that is used when carrying out embodiments of a method in accordance with the present disclosure;
  • Fig. 10A depicts a web handling device of an apparatus for manufacturing a web-based absorbent product in accordance with the present disclosure that is used when carrying out embodiments of a method in accordance with the present disclosure;
  • Fig. 10A depicts a web handling device of an apparatus for manufacturing a web-based absorbent product in accordance with the present disclosure that is used when carrying out embodiments of a method in accordance with the present disclosure;
  • FIG. 10B depicts an alternative web handling device that involves stages for creping a web-based absorbent product
  • FIG. 11 is a block diagram illustrating features of an embodiment of a method for manufacturing a web-based absorbent product in accordance with the present disclosure
  • Fig. 12 is a graph illustrating the relationship between a fiber content of a fibrous foam and an air content of the fibrous foam
  • Fig. 13 is a graph illustrating the relationship between a solids content of a fibrous foam and an air content of the fibrous foam
  • Fig. 14 is a graph illustrating a correlation between at fiber volume fraction of a fibrous foam and a storage modulus G ⁇ of the fibrous foam
  • Fig. 12 is a graph illustrating the relationship between a fiber content of a fibrous foam and an air content of the fibrous foam
  • Fig. 13 is a graph illustrating the relationship between a solids content of a fibrous foam and an air content of the fibrous foam
  • Fig. 14 is a graph illustrating a
  • FIG. 15 is a photo of a stress-controlled TA Instruments DHR- 2 rheometer equipped with a vane-in-cup geometry that was used to measure rheological properties of fibrous foam samples manufactured in accordance with the present disclosure
  • Fig. 16 depicts a cross-section through a ply of a of an embodiment of an absorbent web-based product in accordance with the present disclosure
  • Fig. 17 depicts a cross-section through a multi-ply product comprising an embodiment of an absorbent web-based product in accordance with the present disclosure
  • Fig. 18 depicts a cross-section through a multi-ply product comprising two plies in accordance with embodiments of an absorbent web-based product in accordance with the present disclosure
  • Fig. 16 depicts a cross-section through a ply of a of an embodiment of an absorbent web-based product in accordance with the present disclosure
  • Fig. 17 depicts a cross-section through a multi-ply product comprising an embodiment of an absorb
  • FIG. 19 depicts a cross-section through a multi-ply product comprising a foam formed ply in accordance with embodiments of an absorbent web-based product in accordance with the present disclosure
  • Fig. 20 depicts a cross-section through a multi-ply product comprising a foam formed ply in accordance with embodiments of an absorbent web-based product in accordance with the present disclosure
  • Fig. 21 depicts a cross-section through a multi-ply product comprising a foam formed ply in accordance with embodiments of an absorbent web-based product of the present disclosure
  • Fig. 20 depicts a cross-section through a multi-ply product comprising a foam formed ply in accordance with embodiments of an absorbent web-based product in accordance with the present disclosure
  • Fig. 21 depicts a cross-section through a multi-ply product comprising a foam formed ply in accordance with embodiments of an absorbent web-based product of the present disclosure
  • FIG. 22 depicts a cross-section through a multi-ply product comprising a foam formed ply in accordance with embodiments of an absorbent web-based product of the present disclosure
  • Fig. 23 depicts a cross-section through a multi-ply product comprising a foam formed ply in accordance with embodiments of an absorbent web-based product of the present disclosure
  • Fig. 24 depicts a cross-section through a multi-ply product comprising a foam formed ply in accordance with embodiments of an absorbent web-based product of the present disclosure
  • Fig. 25A depicts a microCT measurement image of a top side of a structured ply (a TAD ply) manufactured according to a conventional TAD manufacturing process
  • FIG. 25B shows a microCT measurement image of a top side of a foam formed ply manufactured according to the present disclosure
  • Fig. 26A depicts a microCT measurement image of a bottom side of a structured ply (a TAD ply) manufactured according to a conventional TAD manufacturing process
  • Fig. 26B shows a microCT measurement image of a bottom side of a foam formed ply manufactured according to the present disclosure
  • Fig. 27A depicts a microCT measurement image of a top side of a structured ply (a TAD ply) manufactured according to a conventional TAD manufacturing process
  • Fig. 27B shows a microCT measurement image of a top side of a foam formed ply manufactured according to the present disclosure
  • Fig. 26A depicts a microCT measurement image of a bottom side of a structured ply (a TAD ply) manufactured according to a conventional TAD manufacturing process
  • Fig. 27B shows a microCT measurement image of a top side of a foam
  • FIG. 28A depicts a microCT measurement image of a bottom side of a structured ply (a TAD ply) manufactured according to a conventional TAD manufacturing process
  • Fig. 28B shows a microCT measurement image of a bottom side of a foam formed ply manufactured according to the present disclosure
  • Fig. 29A depicts a microCT measurement images of cross-sections taken through a structured ply (a TAD ply) manufactured according to a conventional TAD manufacturing process
  • Fig. 29B shows a microCT measurement image of cross-sections taken through a foam formed ply manufactured according to the present disclosure.
  • Fig. 1A depicts a schematic view of an apparatus 10 for manufacturing an absorbent web-based product in accordance with an embodiment of the present disclosure.
  • the apparatus 10 of Fig. 1A comprises a fibrous foam preparation means 20 that prepares a fibrous foam.
  • the fibrous foam preparation means 20 of Fig. 1A is a mixer. However, the mixer is an example only, and other embodiments may comprise a different fibrous foam preparation means.
  • the fibrous foam preparation means may comprise or consist of one or several devices.
  • the arrows laterally pointing towards the fibrous foam preparation means 20 represent a supply means 25 that may at least supply fibers, one or more surface active agents, a liquid, and gas to the fibrous foam preparation means 20.
  • the supply means 25 comprises a solids supply means (symbolized by one of the lateral arrows) that supplies solids.
  • the solid supply means may supply a solids content of 5% to 60% by weight, and wherein at least 80% by weight of the solids are fibers.
  • the supply means 25 also comprises one or several liquid supply means (symbolized by one or several of the lateral arrows) supplying liquid to the fibrous foam preparation means 20, to form the fibrous foam.
  • a fibrous foam may, for example, be formed with a solids content of 5% to 60% by weight of the fibrous foam, optionally of more than 10% by weight of the fibrous foam, and a liquid content of 40% to 95% by weight of the fibrous foam.
  • the supplied solids are dispersed in the solids-liquid dispersion that is to be prepared as a fibrous foam.
  • the supply means 25 may comprise a rheology modifier supply means that supplies a rheology modifier.
  • a fiber content of a fibrous foam prepared by the apparatus depicted in Fig. 1A may be 5% to 60% by weight, a surface active agents content may be 0.02% to 1.20% by weight, a liquid content may be 40% to 95% by weight, and a gas content may be 64% or more by volume. Narrower ranges that may be used for embodiments are defined above.
  • the supply means 25 may supply liquid, in which the surface active agents, the fibers, and the gas (and, optionally, as well as other chemical components) are dispersed, comprising at least 80% by weight of water, and/or gas being dispersed in the liquid and/or the foam comprising at least 95% air by volume.
  • the fibrous foam may, for example, be prepared such that it has a fiber volume fraction of 0.040 or less. Optionally, narrower ranges for the fiber volume fraction are associated with embodiments, as discussed above.
  • the fibrous foam may be prepared to have a solids content with a solids volume fraction is 0.040 or less, optionally 0.035 or less, or 0.030 or less, or 0.025 or less, or 0.020 or less, or 0.015 or less, or 0.01 or less, or 0.005 or less, and wherein at least 80% of the solids content is the fiber content.
  • the fibrous foam preparation means 20 may prepare a gas-liquid dispersion that comprises a liquid content of at least 80% by weight of water, and/or a gas content of at least 95% air by volume.
  • the 1A comprises a transportation means 30 including a section that constitutes a foam layer formation means 33 that forms the fibrous foam (that was prepared by the fibrous foam preparation means 20) into a foam layer.
  • the apparatus 10 supplies fibrous foam prepared by the fibrous foam preparation means 20 to the transporting means 30. This is symbolized in Fig. 1A by the arrow pointing from the fibrous foam formation means 20 to the transportation means 30.
  • the transportation means 30 transports the fibrous foam and, in the section that constitutes the foam layer formation means 33, forms it into a foam layer.
  • the transporting means 20 of Fig. 1A comprises a pressurization section that increases a pressure applied to the liquid slurry or the fibrous foam during the transporting in a downstream direction of transportation (the direction from left to right in the figure).
  • the formed foam layer is then transferred to and conveyed with the permeable conveyor 40.
  • the apparatus 10 of Fig. 1A further comprises a draining means 50 that drains the fibrous foam in the foam layer to form a fibrous web having a liquid content of 20% to 85% by weight.
  • the apparatus 10 of Fig. 1A comprises a drying means 60 that dries the fibrous web to form an absorbent web-based product.
  • the apparatus 10 of Fig. 1A also comprises a web handling device 70 comprising a winding device 72.
  • the web handling device 70 removes a manufactured web-based absorbent product from a conveyor section 71 and feeds it into the winding device 72.
  • Fig. 1B schematically depicts an embodiment of an apparatus 10 for manufacturing an absorbent web-based product.
  • Figs. 1A and 1B are similar, and analogous components are denoted by the same reference numerals. A description of like components will not be repeated, but reference is instead made to the description of Fig. 1A.
  • a difference between Figs. 1A and 1B is that the fibrous foam formation means / processing means / transportation means 20A of the embodiment of Fig. 1B is schematically depicted more specifically, namely, as a transportation means comprising a rotatable means that is rotatable by a motor 35.
  • the apparatus 10 of Fig. 1B brings the liquid slurry and/or foam and/or fibrous foam being transported by the transporting means into contact with the rotatable means . More generally, as already described in the context of Fig.
  • liquid, fibers e.g., dry fibers
  • chemical components such as a surface active agent
  • the rotatable means is rotated by the motor 35 to transport the fibrous foam.
  • the revolution speed of the rotatable means is, depending on the embodiment, set within the range of from 100 to 5000 rpm (revolutions per minute).
  • the rotating of the rotatable means by the motor 35 may at the same time, by the same mechanical movement, promote fibrous foam formation, processing, as well as transportation.
  • the rotating of the rotatable means by the motor 35 may promote one or several of the following: transporting, mixing, defiberizing, exerting pressure on, and building up pressure on the fibrous foam.
  • the foam layer formation means / processing means / transporting means 20 of Fig. 1A or the foam layer formation means / processing means / transporting means 20A of Fig. 1B may each be any one of the following: an industrial mixer, a screw kneader, an industrial kneading machine, an extruder, a mono or twin screw machine, a mono or twin screw continuous kneader, a twin screw or multi screw machine, a conical screw mixer, comprising the at least one rotatable means.
  • the foam layer formation means / processing means / transporting means 20A of Fig. 1B comprises a housing that houses the rotatable means.
  • a minimum distance i.e., a minimum distance reached when considering all positions, in particular, all rotation positions of the rotatable means) between the rotatable means and an opposing inner surface of the housing is in the range of 0.3 to 20 mm.
  • the transporting means 30A comprises a section that constitutes a foam layer formation means 33A that form the fibrous foam into a foam layer.
  • the foam layer is then, analogously to what was described in the context of Fig. 1A provided to the permeable conveyor 40.
  • the permeable conveyor 40 conveys the foam layer past the draining means 50 and the drying means 50.
  • the mixer 20B may be used to prepare foam, and in the present case, it is used to prepare fibrous foam.
  • the mixer 20B is an example of a processing means that processes a liquid slurry or a foam and fibers into the fibrous foam.
  • the mixer 20B may be used to partially prepare a fibrous foam, and the preparation may then be continued in a fibrous foam formation means 20 as shown in Fig. 1A or in a fibrous foam formation means 20A as shown in Fig. 1B.
  • a part of the fibrous foam formation may already take place prior to the processing with the fibrous foam formation means / processing means / transporting means of embodiments as illustrated in Figs. 1A and 1B.
  • the entire fibrous foam formation takes place in an integral fibrous foam formation means / processing means / transporting means (e.g., as shown in Figs. 1A and 1B).
  • the mixer 20B comprises a rotor 21 that may be used to mix the supplied ingredients and thereby apply shear forces, defiberize the fibers, deflocculate, refine, disperse, disintegrate, change fiber shapes, and heat the slurry and/or foam (fibrous foam towards the end of the process), as well as heat the slurry or foam, while chemical additives are being added thereto.
  • the mixer 20B comprises an input 23 for inputting chemicals and/or fibers, as well as an air input comprising a compressor 22 for compressing air to be supplied into the mixing chamber. After the mixing process, the mixer 20B outputs a fibrous foam to the transportation pump 24 that may be, depending on the embodiment, the transportation means itself, or may pump the fibrous foam towards the transporting means 30.
  • FIG. 3A depicts a perspective view of a part of exemplary foam layer formation means 33/33A.
  • This exemplary foam layer formation means 33/33A is a die 33B.
  • the die 33B comprises an inlet 41, through which fibrous foam is fed into the die 33B, as well as an outlet 42.
  • the die 33B forms the fibrous foam into a foam layer.
  • the die 33B comprises an outlet 42 through which the foam layer exits the die 33B.
  • Fig. 3A depicts the die 40A from the outside.
  • the die 33B comprises a housing with an upper cover 43 and a lower cover 44 that together embed a hollow space which has a shape that is designed to form the fibrous foam being transported in a downstream direction into a planar shape, i.e., to form a foam layer.
  • FIG. 3B depicts the die 33B of Fig. 3A, but without the upper cover 43, so that a part of the inside (the hollow space) within the die 33B is visible.
  • the space inside the die comprises a high but narrow portion 45 close to the inlet 41 where the fibrous foam starts to be broadened and flattened, and a shallow but broad portion 46 close to the outlet 42.
  • Fig. 3C depicts a sectional side view of the die 33B of Figs. 3A and 3B. In the view of Fig.
  • Fig. 4A depicts a sectional view of a twin screw pump 30B as an example of a transportation means of an apparatus for manufacturing a web-based absorbent product in accordance with the present disclosure (the transportation means may also be the processing means and/or the foam layer formation means) that is used when carrying out embodiments of a method in accordance with the present disclosure.
  • the twin screw pump 30B comprises a pump body 34 with an inlet 39 and an outlet 36.
  • the pump body 34 houses a first screw 37A and a second screw 37B, together forming the twin screw, as well as corresponding shafts 38A and 38B.
  • Fig. 4B depicts a sectional view of a lobe pump 30C as an example of a positive displacement pump as a transportation means of an apparatus for manufacturing a web-based absorbent product in accordance with the present disclosure (the transportation means may also be the processing means and/or the foam layer formation means) that is used when carrying out embodiments of a method in accordance with the present disclosure.
  • the lobe pump 30C comprises a housing 38 with an inlet 36A and an outlet 39A, as well as two lobes 37C and 37D housed therein for displacing the fibrous foam.
  • FIG. 5A is a perspective view of an extruder 30D, as an example of a transportation means of an apparatus for manufacturing a web-based absorbent product in accordance with the present disclosure (the transportation means may also be the processing means and/or the foam layer formation means) that is used when carrying out embodiments of a method in accordance with the present disclosure.
  • the extruder 30D Prior to reaching the extruder 30D, fibrous foam is prepared, and the extruder 30D then transports the fibrous foam in a downstream direction by rotating the extruder screw 32 that is located inside of the extruder housing 31.
  • Fig. 5B shows the extruder 30D, but with a part of the housing removed, to expose the interior.
  • the extruder 30D comprises an extruder screw 32.
  • Fig. 6A shows a part of a double screw 32A (two extruder screws that operate together) within their common housing 31A.
  • a distance of closest approach between the two screws of the double screw 32A is in the case of the embodiment shown around 1.25mm. However, in the case of other embodiments, the distance of closest approach may be different and, e.g., lie somewhere else within the range of from 0.3 mm to 20 mm.
  • Fig. 6B shows the part of the double screw 32A in question without the housing 31A.
  • Fig. 6C shows a sectional view of the double screw 32A of Figs.
  • Fig. 7A depicts a part of another embodiment of an extruder comprising multiple screws 32B located inside of their common housing 31B.
  • the housing 31B has a cylindrical shape, but this is just an example, as the shape of the housing may differ strongly from embodiment to embodiment.
  • the multiple screws 32B are in the case of the embodiment of Fig. 7A arranged circumferentially around a central bearing unit 45.
  • Fig. 7B depicts a part of an embodiment of an extruder comprising multiple screws 32C located inside of their common housing 31C.
  • the housing 31C has a planar cuboid shape, as another example of a possible shape of a housing.
  • Fig. 8 depicts a draining means 50 of an apparatus for manufacturing a web-based absorbent product in accordance with the present disclosure that is used when carrying out embodiments of a method in accordance with the present disclosure.
  • the fibrous foam Prior to reaching the draining means 50, the fibrous foam has been formed into a foam layer L.
  • the foam layer L is being conveyed in a downstream direction (the direction from left to right in Fig. 8, as indicated by the arrow pointing to the right).
  • the draining means 50 comprises a vacuum station 51 that applies a vacuum to the foam layer L and in this way removes liquid (defluidizes, in particular, in the case of the illustrated embodiment: dewaters) it, to form a fibrous web having a liquid content of 20% to 85% by weight.
  • the draining means 50 comprises a vacuum pump 52 for generating the vacuum used for dewatering the foam layer L.
  • Fig. 9 depicts a drying means 60 of an apparatus for manufacturing a web-based absorbent product in accordance with the present disclosure that is used when carrying out embodiments of a method in accordance with the present disclosure. Prior the step of drying carried out by the drying means 60, the fibrous web W is formed.
  • Fig. 10A depicts a web handling device 70 of an apparatus for manufacturing a web-based absorbent product in accordance with the present disclosure that is used when carrying out embodiments of a method in accordance with the present disclosure.
  • the web handling device 70 comprises a winding device 72.
  • the web handling device 70 removes a manufactured web-based absorbent product from a conveyor section 71 and feeds it into the winding device 72.
  • Fig. 10B depicts an alternative web handling device 70A that involves stages for creping the web-based absorbent product.
  • the web handling device 70A comprises a creping blade 73 (also referred to as a fixed doctor blade) and a Yankee cylinder 74.
  • the zone between the tip of the crepe blade 73 and the surface of the Yankee surface is referred to as the crepe pocket where the creping takes place.
  • the speed differential between the Yankee cylinder (where the uncreped web-based absorbent product is fed) and the reel (the creped web-based absorbent product after creping) from where the web-based absorbent product is supplied to the converting process to make the finished products defines the crepe ratio.
  • Fig. 11 is a block diagram illustrating features of an embodiment of a method for manufacturing a web-based absorbent product in accordance with the present disclosure. In particular, Fig.
  • step S0a for example, relates to the supplying of water such that the water content is 40% to 95% by weight, fibers such that the fiber content is 5% to 60% by weight, and surface active agents such that surface active agents content of 0.02% to 1.20% by weight
  • step S0b relates to the supplying of air.
  • step S0a and S0b are meant to be representative for the supplying only.
  • step S1 the fibrous foam is prepared, wherein the preparation includes dispersing the supplied fibers and the supplied one or more surface active agents in the supplied liquid, as well as dispersing gas in the liquid until a desired gas content (of 64% or more by volume is reached).
  • the desired gas content is set differently (it may, e.g., be set at 70%, 75%, 80%, 85%, 90%, or 95%, etc.).
  • the air content is regularly (in some cases continuously, in other cases at intervals, etc.) measured, and the measured values are fed back to the control unit (step S3), and the control unit controls the preparation process, including, in particular, the mixing.
  • Fig. 12 is a graph illustrating the relationship between the fiber content (in weight %) of a fibrous foam and the air content (in volume %).
  • Fig. 12 shows lines of constant fiber volume fraction. That is, the same fiber volume fraction can be achieved with different fiber contents by adjusting the corresponding air content, and vice versa.
  • Fig. 13 is an analogous graph, this time showing the relationship between the solids content (in weight %) of a fibrous foam and the air content (in volume %).
  • the solids volume fraction is based on all the solids included in the fibrous foam.
  • the solids volume fraction may, for some embodiments, essentially be the fiber volume fraction, but for other embodiments, 99%, 98%, 97%, or less (e.g., 90%) of the solids may be fibers. That is, the solids volume fraction may be considered more general in this regard.
  • Fig. 13 shows lines of constant solids volume fraction. That is, the same solids volume fraction can be achieved with different solids contents by adjusting the corresponding air content, and vice versa.
  • the storage modulus G ⁇ [Pa] represents the elastic component of the material stiffness.
  • the storage modulus G ⁇ [Pa] may be considered to represent the energy elastically stored in a material when it is deformed and that can then be reversibly released.
  • the storage modulus G ⁇ [Pa] is one of two components that make up the complex modulus G* (or complex modulus), which is a measure of the materials resistance to deformation, i.e., the overall stiffness of a viscoelastic material.
  • the other component is the loss modulus, which represents the energy dissipated in the form of heat when a material undergoes deformation.
  • Fig. 15 is a photo of a stress-controlled TA Instruments DHR-2 rheometer equipped with a vane-in-cup geometry that was used to measure rheological properties of fibrous foam samples manufactured in accordance with the present disclosure (and using apparatuses in accordance with the present disclosure.
  • Fig. 15 is a photo of a stress-controlled TA Instruments DHR-2 rheometer equipped with a vane-in-cup geometry that was used to measure rheological properties of fibrous foam samples manufactured in accordance with the present disclosure (and using apparatuses in
  • FIG. 16 depicts a cross-section through a ply of an embodiment of an absorbent web-based product 100 in accordance with the present disclosure.
  • the product 100 of Fig. 16 is a single ply product that was made using the foam forming technology described herein. It comprises over 70 wt.-% of fiber material based in its total weight.
  • the product 100 of Fig. 16 may comprise at least 0.2 wt.-% of one or more binders based on the total weight of the absorbent web-based product.
  • Fig. 16 may comprise at least 0.05 wt.-% of one or more rheology modifiers based on the total weight of the absorbent web-based product.
  • the product 100 of Fig. 16 may comprise at least 0.01 wt.-% of one or more surface active agents based on the total weight of the absorbent web-based product.
  • the product 100 of Fig. 16 may comprise at least 0.2 wt.-% of one or more slipping agents based on the total weight of the absorbent web-based product.
  • the product 100 was manufactured on the basis of embodiments of structural components and method steps described with reference to preceding figures.
  • Fig. 17 depicts a cross-section through a multi-ply product 110 comprising an embodiment of an absorbent web-based product 111 in accordance with the present disclosure.
  • the product 110 of Fig. 17 is a two-ply product.
  • the absorbent-web based product 111 of the multi-ply product 110 is the same as the product 100 depicted in Fig. 16, and the description thereof will not be repeated.
  • the multi-ply product 110 comprises a further ply 112.
  • This additional ply 112 may be a non-woven ply or tissue paper ply, such as a conventional wet press paper ply, a structured ply (e.g., TAD, ATMOS, etc.), or a textured ply.
  • a non-woven ply or tissue paper ply such as a conventional wet press paper ply, a structured ply (e.g., TAD, ATMOS, etc.), or a textured ply.
  • FIG. 18 depicts a cross-section through a multi-ply product 120 comprising two plies 121 and 123 in accordance with embodiments of an absorbent web-based product in accordance with the present disclosure.
  • the product 120 of Fig. 18 is a three ply product.
  • the absorbent-web based product plies 121 and 123 of the multi- ply product 120 are the same as the ply constituting the product 100 depicted in Fig. 16, and the description thereof will not be repeated.
  • the plies 121 and 123 may be the same or they may differ.
  • the multi-ply product 120 comprises a further ply 122.
  • This additional ply 122 may be a non-woven ply or tissue paper ply, such as a conventional wet press paper ply, a structured ply (e.g., TAD, ATMOS, etc.), or a textured ply.
  • one foam formed ply may be combined with two or more further plies, or other selected numbers of foam formed plies may be combined with selected numbers of further plies, each of them being a non-woven ply or tissue paper ply, such as a conventional wet press paper ply, a structured ply (e.g., TAD, ATMOS, etc.), or a textured ply.
  • the further plies may be the same or may differ.
  • Fig. 19 depicts a cross-section through a multi-ply product 130 comprising a foam formed ply 131 in accordance with embodiments of an absorbent web-based product in accordance with the present disclosure.
  • the product 130 of Fig. 19 is a two-ply product.
  • the foam formed ply 131 was manufactured the same way as the product 100 depicted in Fig. 16, but the ply 131 was additionally embossed.
  • the multi-ply product 130 comprises a further ply 132.
  • This additional ply 132 may be a non-woven ply or tissue paper ply, such as a conventional wet press paper ply, a structured ply (e.g., TAD, ATMOS, etc.), or a textured ply.
  • one foam formed ply may be combined with two or more further plies, or other selected numbers of foam formed plies may be combined with selected numbers of further plies, each of them being a non-woven ply or tissue paper ply, such as a conventional wet press paper ply, a structured ply (e.g., TAD, ATMOS, etc.), or a textured ply.
  • the further plies may be the same or may differ.
  • Fig. 20 depicts a cross-section through a multi-ply product 140 comprising a foam formed ply 141 in accordance with embodiments of an absorbent web-based product in accordance with the present disclosure.
  • the product 140 of Fig. 20 is a two-ply product.
  • the foam formed ply 141 was manufactured the same way as the product 100 depicted in Fig. 16, but the ply 141 was additionally embossed.
  • the multi-ply product 140 comprises a further ply 142.
  • This additional ply 142 may be a non-woven ply or tissue paper ply, such as a conventional wet press paper ply, a structured ply (e.g., TAD, ATMOS, etc.), or a textured ply.
  • a conventional wet press paper ply e.g., TAD, ATMOS, etc.
  • a structured ply e.g., TAD, ATMOS, etc.
  • a textured ply e.g., a textured ply.
  • one foam formed embossed or non-embossed ply may be combined with two or more further embossed or-non embossed plies, or other selected numbers of foam formed plies may be combined with selected numbers of further plies, each of them being a non-woven ply or tissue paper ply, such as a conventional wet press paper ply, a structured ply (e.g., TAD, ATMOS, etc.), or a textured ply.
  • the further plies may be the same or may differ.
  • the foam formed plies may also be the same or may mutually differ.
  • FIG. 21 depicts a cross-section through a multi-ply product 150 comprising a foam formed ply 151 in accordance with embodiments of an absorbent web-based product of the present disclosure.
  • the multi-ply product 150 of Fig. 21 comprises a further ply 152, and the two plies 151 and 152 were laminated together.
  • the foam formed ply 151 was manufactured analogously as the product 100 depicted in Fig. 16.
  • Fig. 22 depicts a cross-section through a multi-ply product 160 comprising a foam formed ply 161 in accordance with embodiments of an absorbent web-based product of the present disclosure.
  • Fig. 22 is a three-ply product comprising further plies 162 and 163.
  • the three plies 161, 162, and 163 were laminated together.
  • the foam formed ply 161 was manufactured analogously as the product 100 depicted in Fig. 16.
  • Fig. 23 depicts a cross-section through a multi-ply product 170 comprising a foam formed ply 171 in accordance with embodiments of an absorbent web-based product of the present disclosure.
  • the foam formed ply 171 was embossed.
  • the multi-ply product 170 of Fig. 23 comprises a further ply 172, and the two plies 171 and 172 were laminated together.
  • Fig. 24 depicts a cross-section through a multi-ply product 180 comprising a foam formed ply 181 in accordance with embodiments of an absorbent web-based product of the present disclosure.
  • the foam formed ply 181 was embossed.
  • the multi-ply product 180 of Fig. 24 comprises a further ply 182 that is also an embossed ply, and the two plies 181 and 182 were laminated together.
  • the foam formed ply 181 was manufactured analogously as the product 100 depicted in Fig. 16.
  • Fig. 24 depicts a cross-section through a multi-ply product 180 comprising a foam formed ply 181 in accordance with embodiments of an absorbent web-based product of the present disclosure.
  • the foam formed ply 181 was embossed.
  • the multi-ply product 180 of Fig. 24 comprises a further ply 182 that is also an embossed ply, and the two plies 181 and 182 were laminated
  • FIG. 25A shows a microCT measurement image of a top side of a structured ply (a TAD ply) manufactured according to a conventional TAD manufacturing process. The top side was not in contact with an imprinting belt.
  • Fig. 25B shows a microCT measurement image of a top side of a foam formed ply manufactured according to the present disclosure. The top side was not in contact with an imprinting belt. A comparison between the two images shows the much greater homogeneity of the fiber distribution in the foam formed ply as compared to the TAD ply.
  • Fig. 26A shows a microCT measurement image of a bottom side of a structured ply (a TAD ply) manufactured according to a conventional TAD manufacturing process.
  • Fig. 26B shows a microCT measurement image of a bottom side of a foam formed ply manufactured according to the present disclosure. The bottom side was in contact with an imprinting belt. A comparison between the two images shows the much greater homogeneity of the fiber distribution in the foam formed ply as compared to the TAD ply.
  • Fig. 27A shows a microCT measurement image of a top side of a structured ply (a TAD ply) manufactured according to a conventional TAD manufacturing process and in particular depicts four sections A2, B2, C2, and D2 from which cross sections were visualized and inspected in further detail. Likewise, Fig.
  • FIG. 27B shows a microCT measurement image of a top side of a foam formed ply manufactured according to the present disclosure and depicts four sections A1, B1, C1, and D2 from which cross sections were visualized and inspected in further detail.
  • Fig. 28A shows a microCT measurement image of a bottom side of a structured ply (a TAD ply) manufactured according to a conventional TAD manufacturing process and in particular depicts the same four sections A2, B2, C2, and D2 from which samples were taken and inspected in further detail as shown in Fig. 27A.
  • FIG. 28B shows a microCT measurement image of a bottom side of a foam formed ply manufactured according to the present disclosure and depicts the same four sections A1, B1, C1, and D2 from which samples were taken and inspected in further detail as shown in Fig. 27B.
  • Fig. 29A shows microCT measurement images of cross-sections A2, B2, C2, and D2 taken through the structured ply (a TAD ply) manufactured according to a conventional TAD manufacturing process.
  • Fig. 29B shows microCT measurement images of cross-sections A1, B1, C1, and D1 taken through the foam formed ply manufactured according to the present disclosure.
  • the pressure foot is movable at a speed rate of 2.0 + 0.2 mm/s.
  • a usable apparatus is a thickness meter type L & W SE050 (available from Lorentzen & Wettre, Europe).
  • the finished product to be measured is cut into pieces of 20 x 25 cm and conditioned in an atmosphere of 23°C, 50 % RH for at least 12 hours.
  • For the measurement one sheet is placed beneath the pressure plate which is then lowered.
  • the thickness value for the sheet is then read off 5 seconds after the pressure has been stabilized.
  • the thickness measurement is then repeated nine times with further samples treated in the same manner.
  • the mean value of the 10 values obtained is taken as thickness of one sheet (“one-sheet caliper”) of the finished product measured.
  • the dry solids content of the fibrous foam was determined right after forming and dewatering.
  • the test samples were weighted wet and after drying, and the dry solids content was calculated according to the following equation (3): 1 00 (in %) (3) wherein m is the dry mass of the sample and m is the wet mass of the sample.
  • the cup was placed in a temperature-controlled Peltier jacket that kept the temperature of the sample at 25 °C during all rheological measurements.
  • Fiber foam samples were loaded into the cup with the help of a syringe whose end had been cut open, making sure that the whole cup was filled with fiber foam and that there were no air pockets inside the sample.
  • the air content of the fibrous foam sample was determined by weighing the foam-filled cup before inserting it into the rheometer. Thereafter, the vane geometry was lowered into the sample so that the blades of the vane were located in the middle of the cup vertically (16 mm both from the bottom of the cup and from the upper surface of the foam sample).
  • a picture of the vane-in-cup measurement setup is shown in Fig. XY.
  • the pulp (NBSK fluff pulp) was fed to a laboratory hammermill (Kvarn H01, M-NR 4.1224599, available from Kamas Industries AB) to produce defiberized fluff pulp.
  • the dry pulp fibers were pre- moisturized by spraying with water to a moisture content of 60% by weight inside a Forberg paddle mixer.
  • a blend of components as described in Table 1 was introduced in a twin-screw extruder using pumps.
  • the moisturized fluff pulp was then introduced into the extruder through a gravimetric feeder from Coperion K-Tron.
  • the wet-strength resin (Maresin WS505) was introduced after the fiber feeding.
  • the twin-screw extruder was connected to a static die having a width of 250mm and an opening (height) of 2.5mm.
  • the total throughput was set at 30 kg/h and the twin screw rotation speed was set at 2400 rpm.
  • the fiber consistency of the fibrous foam was measured to be 9% by weight and the total solids content was measured to be 10% by weight.
  • the fiber volume fraction was calculated to be 0.0121 after the preparation of the fibrous foam.
  • Example 1 I ngredients Fluff pulp SL10 CMC PAE Water Solution 40% fiber 250 g/L 50 g/L 50 g/L concentration dryness A dded amount 1.8 kg 0.480 L 1.756 L 0.702 L 4.466 L Final 18% fiber 15 g/L 50kg/T 20 kg/t 8L concentration consistency per of of water fibers fibers Table 1. List of ingredients and quantities used in Example 1 The fibrous web formed through the static die was spread over a standard through-air-drying (TAD) fabric and drained (dewatered) through five consecutive vacuum boxes with increasing levels of vacuum (going from -0.05 bars to -0.6 bars). The speed of the fabric was 8 meters per minute.
  • TAD through-air-drying
  • the dry pulp fibers were pre- moisturized by spraying with water to a moisture content of 60% by weight inside a Forberg paddle mixer.
  • a dilute suspension of (2.5% by weight aqueous solution) of the low viscosity CMC (LV-CMC; from Sigma-Aldrich) was used for the moisturizing of the fibers.
  • a blend of components as described in Table 3 was introduced in a Pico-Mix foam mixer (commercially available from Hansa) to prepare a foam with an air content of 95% by volume.
  • the foam was introduced into a twin-screw extruder.
  • the moisturized fluff pulp was then introduced into the extruder through a gravimetric feeder from Coperion K-Tron.
  • the wet-strength resin (Maresin WS505) was introduced after the fiber feeding.
  • the twin-screw extruder was connected to a static die having a width of 250mm and an opening (height) of 2.5mm.
  • the total throughput was set at 30 kg/h and the twin screw rotation speed was set at 2400 rpm.
  • the fiber consistency of the fibrous foam was measured to be 20% by weight and the total solids content was measured to be 10% by weight.
  • the fiber volume fraction was calculated to be 0.0118 after the preparation of the fibrous foam.

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Abstract

La présente divulgation concerne un procédé de fabrication d'un produit absorbant sous forme de bande comprenant les étapes suivantes : la préparation d'une mousse fibreuse comprenant une dispersion de fibres et un ou plusieurs agents de surface dans un liquide, avec une teneur en fibres de 5 % à 60 % en poids, une teneur en agents tensioactifs de 0,02 % à 1,20 % en poids, et une teneur en liquide de 40 % à 95 % en poids, et l'introduction et la dispersion de gaz dans le liquide jusqu'à ce qu'une teneur en gaz de 64 % ou plus en volume soit atteinte ; la formation d'une couche de mousse à partir de la mousse fibreuse, l'égouttage de la mousse fibreuse dans la couche de mousse pour former une bande fibreuse, la teneur en liquide de la bande fibreuse, étant comprise entre 20 % et 85 % en poids, et le séchage de la bande fibreuse, afin d'obtenir un produit absorbant sous forme de bande fibreuse,
PCT/EP2023/084565 2023-12-06 2023-12-06 Procédé de fabrication de produit absorbant sous forme de bande, produit absorbant sous forme de bande et appareil de fabrication d'un produit absorbant sous forme de bande Pending WO2025119469A1 (fr)

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WO2002055774A2 (fr) * 2000-11-14 2002-07-18 Weyerhaeuser Co Produit cellulosique reticule forme par un procede d'extrusion
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