Classifications

• • 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
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/21—Macromolecular organic compounds of natural origin; Derivatives thereof
  • D21H17/24—Polysaccharides
  • D21H17/28—Starch
• • 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
  • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
  • D21H11/12—Pulp from non-woody plants or crops, e.g. cotton, flax, straw, bagasse
• • 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
  • D21H15/00—Pulp or paper, comprising fibres or web-forming material characterised by features other than their chemical constitution
• • 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
  • D21H21/18—Reinforcing agents

Definitions

• the present invention relates to novel compositions for use in the wet-end of papermaking.
• it relates to compositions comprising both starch and a non-wood plant fiber, and to their use for increasing the dry strength of paper products.
• cellulose is mixed with water and pulped to form a slurry (or “cellulosic pulp”).
• the slurry is then applied to a screen to orient the cellulose fibers and form a paper web. Excess liquid is allowed to drain off. This process is referred to as “the wet-end” of papermaking.
• the web is then passed through a press section, to further reduce water content, followed by a drying step, typically using steam- or oil-heated drying cylinders.
• the dried paper web may then be impregnated with a sizing composition or coated before being cut to size.
• the strength of the finished paper product will depend on a number of factors including, for example, the use and nature of any sizing or coating compositions, the use and nature of any wet-end additives and, of course, the nature of the pulp itself.
• Virgin wood pulp typically gives a stronger paper than pulp obtained from recycled paper.
• the strength of a paper product will diminish with every re-pulping cycle.
• Dry strength additives for use in the wet-end have typically consisted of cationic starches.
• Cationic starch normally interacts with anionic cellulose fibers in the pulp to form complex matrices, thereby strengthening the paper web.
• cationic starches have been found to be rather ineffective when used in combination with recycled materials. It is indeed believed that recycled materials contain high levels of anionic trash which effectively “saturate” the cationic starch and therefore limit its interaction with the anionic cellulose fibers. Papermaking in closed circuits will lead to an accumulation of these trash products together with salts which impair the electrostatic interactions between anionic fibers and the cationic starch. As a result, the use of cationic starches in combination with recycled materials has a lesser ability to effectively increase dry strength.
• starch-based strength additives A number of synthetic alternatives to starch-based strength additives have been proposed. These have included, for instance, polyacrylamide and polyvinylamine and are typically more efficient, even when used in combination with recycled materials. Unfortunately, they are also prohibitively expensive and may be considered undesirable from an environmental perspective.
• composition for use as a strengthening agent in the wet-end of papermaking which comprises a surface modified non-wood plant fiber and a starch component, wherein the plant fiber and starch component are preferably linked.
• a surface modified non-wood plant fiber to increase the dry strength of paper, preferably paper comprising recycled materials and/or paper produced at conductivity levels above 4 mS/cm.
• the present invention provides a composition for use as a strengthening agent in the wet-end of papermaking which comprises a surface modified non-wood plant fiber and a starch component.
• non-wood plant fiber refers to any fibrous material which is not derived from wood, wherein “wood” will be understood to have its common dictionary definition (i.e. the hard, fibrous substance which makes up most of the trunk and branches of a tree).
• suitable non-wood plant fibers will be apparent to a person skilled in the art. They include, but are not limited to, cereal fibers, seed fibers, legume fibers, fruit fibers, algae fibers and mixtures of two or more thereof.
• the plant fibers may be provided as such or in the form of a fibrous material.
• suitable fibrous materials may include, for instance, cereal bran (e.g. wheat bran), vegetable hulls (such as soy hulls and/or pea hulls), bagasse, corn stover, straw, switch grass, citrus fibers (such as citrus pulp fiber), seaweed residue and mixtures of two or more thereof.
• the fibrous material will preferably comprise fibers in an amount of at least 50% by weight, on a dry weight basis, more preferably in an amount of at least 75% by weight.
• Certain fibrous materials may also comprise non-fibrous elements such as proteins or starch.
• soy hulls typically comprise about 10% by weight protein and about 20% by weight starch, in addition to their fibrous content.
• the fibrous material will comprise approximately 50-85% fibers by weight, on a dry weight basis.
• the plant fibers will preferably be anionic (meaning that it will preferably have a net negative charge). According to certain embodiments, they will have a streaming zeta potential (SZP) of between 0 and ⁇ 30 mV, preferably of between ⁇ 1 and ⁇ 20 mV, more preferably of between ⁇ 1 and ⁇ 15 mV. According to another embodiment, they will preferably have an anionicity of 10 to 2000 ⁇ g/g, more preferably of 100 to 1000 ⁇ eq/g (expressed per gram of dry substance, at pH 7).
• SZP streaming zeta potential
• the plant fibers will advantageously be surface modified such that their ability to interact (mechanically or electrostatically) with cellulose fibers in a cellulosic pulp is increased.
• the fibers may be modified to have a greater overall or specific surface area.
• the term “surface modification” or “surface modified” will not be limited to modifications having an effect only on the surface of the fibers. Indeed, the modification(s) may also result in changes to other properties (e.g. the internal structure) of the fibers. Surface modification may be achieved, for example, by milling, heat treatment (e.g. cooking and/or extrusion), chemical modification or any combination thereof.
• the plant fibers may be provided in the form of a powder or flakes.
• composition of the present invention also comprises a starch component.
• the starch component will increase the plant fiber's ability to interact with the cellulosic pulp, acting almost as an adhesive between the plant fibers and the cellulose fibers.
• starch component may refer to one or more native starches, one or more modified starches, one or more starch derivatives (such as a dextrin) or mixtures thereof.
• the starch component may be derived from starches of any type and any origin. For example it may comprise waxy and/or non-waxy starches, and it may be derived from wheat, corn, potato, tapioca, pea or any other available starch source, and mixtures thereof.
• the starch component may have been subjected to one or more modifications, including chemical, enzymatic and/or heat-based modifications.
• the starch component may comprise, for instance, one or more cross-linked, etherified, esterified, hydroxypropylated, and/or thinned starches.
• the starch component will be anionic or cationic, i.e. having a net negative or a net positive charge. More preferably, the starch component will be cationic.
• the starch component will consist of one or more cationic starches.
• the starch component may be contributed as part of a fibrous material.
• the plant fibers may be provided in the form of a fibrous material which may contain certain non-fibrous elements such as starch.
• the fibrous side-stream recovered from wheat processing may contain up to 50% starch by weight. If using this fibrous side-stream as the source of plant fibers, it may not be necessary to add any starch to the composition (or to only add a small amount of starch).
• the starch component will preferably be “activated”, meaning that it will be rendered capable of forming a dispersion in cold water (i.e. at about 20-25° C.).
• the starch component will be solubilised, meaning that it will be formed into (or capable of forming) a stable colloidal dispersion. This can be achieved, for example, by cooking (heat treating, steam treating, etc.), by thinning (e.g. with acid), by extrusion, by pregelatinization, by roll-drying or by any combination thereof.
• the one or more starch components will comprise one or more cold water soluble cationic starches.
• the composition of the present invention will preferably comprise the starch component in an amount of 1-90% by weight, preferably of 1-50% by weight, more preferably of 5-30% by weight, for example 20-25% by weight, based on the total dry weight of the composition.
• the composition will comprise the plant fibers and the starch component in a weight ratio, based on dry weight, of from 1:20 to 20:1, preferably of from 1:1 to 10:1.
• the starch component and non-wood plant fibers will be linked.
• the term “linked” as used herein may refer to a direct or indirect link, whether through absorption, electrostatic interaction, chemical bond or any other means, which allows at least part of the starch component to be retained on the surface of some or all of the plant fibers.
• at least part of the cationic starch component will be linked to the anionic plant fibers through a direct electrostatic link.
• an anionic starch may be linked to the anionic plant fibers through a cationic bridge (e.g. a cationic trivalent or divalent metal ion such as calcium or aluminium, or cationic starch).
• the composition of the present invention will comprise up to 100% by weight, based on total dry weight, of the plant fibers and starch component.
• it will comprise 80-100% by weight of the plant fibers and starch component, more preferably 90-100% by weight, based on total dry weight.
• composition of the present invention may comprise one or more further optional ingredients.
• these will preferably be selected from wet-end additives well known to a person skilled in the art. They may include, for instance, hardeners, flowability improvers, lubricants, antifoamers, releasing agents, optical brighteners, preservatives, yellowing inhibitors, ultraviolet absorbers, antioxidants, insolubilisers, antistatic agents, pH regulators, water-resisting agents, wet strength agents, sizing agents, dewatering aids, grease and oil resistance additives and combinations of two or more thereof.
• the composition of the present invention will not need to include—and will therefore preferably not include—any synthetic dry strength additives.
• the composition of the present invention will preferably include less than 5%, preferably less than 2%, more preferably less than 1% by weight, based on total dry weight, of any synthetic additives, wherein “synthetic additives” will be understood as referring to non-naturally occurring chemical additives such as polyacrylamide, polyvinylamine, melamine resins, urea formaldehyde resins and so on.
• composition of the present invention will preferably be provided in the form of a powder. Alternatively, it may also be provided in the form of a slurry or of an aqueous composition. As such, it may have a total dry substance of between 10% and 98% by weight, preferably of between 50% and 98% by weight, more preferably of between 70% and 95% by weight, based on the total weight of the composition.
• composition of the present invention is intended for use as a strengthening agent.
• it when used in the manufacture of a paper product, it can be used to maintain or increase the product's dry strength (as measured for example by standard CMT, SCT and/or Burst tests). It is also believed that compositions of the present invention will contribute to a good or improved wet strength, that is to a good or improved strength for the wet paper web during the papermaking process, as described in more detail below.
• the composition of the present invention may be used to increase the wet and/or dry strength of paper products containing recycled materials, especially when compared to cationic starch alone.
• the compositions of the present invention are believed to perform at least as well as synthetic agents such as polyacrylamide and/or polyvinylamine.
• the composition of the present invention may also be used to increase the wet and/or dry strength of paper products produced at conductivity levels above 4 mS/cm.
• composition of the present invention is that it is not detrimental to other important properties of the papermaking process such as retention (the retention of cellulose fibers on the web) or dewatering (the ability of water in the paper pulp to be easily removed). In some instances, it is even believed that the composition of the invention may contribute to an improvement in these properties (i.e. increased retention and increased dewatering).
• the present invention further provides a process for the production of the above composition.
• the present invention provides a process for the production of a composition for use as a strengthening agent in the wet end of paper making which comprises:
• the starch component be cationic or anionic
• cationisation or anionisation of the starch component may be performed prior to or during contact with the plant fiber.
• the process of the present invention may comprise the following steps:
• composition comprising a plant fiber and a starch component
• composition comprising a surface modified plant fiber and a starch component
• activation of the plant fiber (through surface modification) and/or starch component may comprise, by way of example only: heat treatment (e.g. cooking, jet cooking, dry or semi-dry heat treatment, extrusion, roll-drying . . . ), mechanical treatment (e.g. dry milling or wet milling), chemical treatment (e.g. oxidation) and/or, for the starch component at least, pregelatinization.
• heat treatment e.g. cooking, jet cooking, dry or semi-dry heat treatment, extrusion, roll-drying . . .
• mechanical treatment e.g. dry milling or wet milling
• chemical treatment e.g. oxidation
• starch component at least, pregelatinization.
• the plant fiber and/or starch component will both be cooked.
• the plant fiber will preferably also be milled.
• the plant fiber will preferably be milled to an average particle size (D 50 ) in the range of 30-500 ⁇ m, preferably in the range of 30-200 ⁇ m, more preferably in the range of 30-100 ⁇ m.
• cooking may consist of jet cooking, e.g. at a temperature in the range of 80-180° C. or of 100-140° C.
• the process of the present invention will preferably further comprise the step of forming a link (or allowing a link to form) between the plant fiber and starch component. As described above, this may be a direct or indirect link.
• the plant fiber and starch component with are linked by electrostatic interaction.
• the process of the present invention will include the step of contacting the plant fiber and starch component in water. This will advantageously be done prior to use of the composition in the wet-end of papermaking, i.e. in clean water, to prevent the starch component from interacting with non-fibrous materials.
• cleaning water will be understood as having its ordinary meaning, that is: it does not refer to waste water or water with high levels of trash (i.e. white water). It need not refer to sterile or de-ionized water either (although of course such “hyper-clean” waters could be used). Instead it will typically refer to fresh water or simple “tap water”.
• a process for the production of a composition for use as a strengthening agent in the wet end of paper making which comprises:
• the starch component and plant fiber will be brought into contact in clean water and then cooked to encourage the formation of links between these two components (i.e. to encourage them to interact).
• the present invention provides a process for the production of a composition for use as a strengthening agent in the wet end of paper making which comprises:
• step (c) heating the aqueous mixture of step (b), preferably at 80-180° C.
• the plant fiber and starch component will be brought into contact at high concentrations.
• high concentrations it is meant that the plant fiber and starch component will preferably be mixed at 1-30% dry solids, more preferably at 5-20% dry solids, although, of course, in certain embodiments, the dry solids could be much higher. Without wishing to be bound by theory, it is believed that such concentrations will encourage interactions between the plant fibers and starch component.
• the composition may be diluted and/or further optional ingredients may be added to it.
• compositions obtainable by this process, together with their use as strengthening agents and paper products made with them, are all part of the present invention.
• the present invention provides a method of producing a paper product comprising the steps of:
• step (c) producing a paper product from the pulp obtained in step (a).
• cellulosic pulp refers to an aqueous suspension of cellulosic fibers as typically used in the paper industry for the production of paper products. It will be understood as including any type of pulp suitable for use in the manufacture of paper products including, for instance, paper sheets, board (cardboard or corrugated board), packaging or case materials and so on. It may include virgin wood pulp, pulp from recycled materials, mechanical pulp, etc. The pulp may be bleached or unbleached and it may or may not include recycled materials.
• the pulp will comprise recycled materials (i.e. recycled cellulose fibers).
• Recycled materials may include any kind of recovered, waste or scrap paper products (“waste products”) which are re-pulped for further use.
• suitable waste products may include, for example, mill broke, pre-consumer waste and/or post consumer waste.
• the recycled materials may or may not be de-inked, bleached or treated in any other way before use and they may include materials that have already been recycled one or more times.
• the pulp may consist entirely of recycled materials. Preferably, it will comprise at least 50% recycled materials by weight, more preferably at lest 75% by weight.
• composition of the present invention is particularly useful in the production of paper products comprising recycled materials.
• composition of the present invention will provide better wet and dry strength properties in the production of paper products comprising recycled materials than cationic starches alone (and at least equivalent properties to their synthetic alternatives), without negatively affecting water drainage, retention or other important parameters.
• the composition of the present invention will be used such that the composition of the present invention is brought into contact with the cellulosic pulp in an amount of 0.2 to 20%, preferably 0.5 to 10%, more preferably 2-6% by weight, based on the dry weight of the pulp.
• paper products of the present invention will preferably comprise surface modified plant fibers and cellulose fibers in a weight ratio of 1:500 to 1:4, more preferably of 1:100 to 1:20, more preferably of 1:60 to 1:30.
• the starch used was of the type C*Bond 05946 available from Cargill Incorporated, with a degree of substitution of 0.042, the wheat fiber was milled wheat bran with an average particle size of 43 ⁇ m and the soy fiber was milled soy hulls with an average particle size of 75 ⁇ m.
• CMT is measured according to the following standard method: DIN EN ISO7263.
• Burst Strength is measured according to the following standard method: Mullen DIN 53141 Part 1 (Tappi 403-OM-85)

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• 2012
  • 2012-07-25 CN CN201280037843.8A patent/CN103732827A/zh active Pending
  • 2012-07-25 CA CA2842911A patent/CA2842911A1/fr not_active Abandoned
  • 2012-07-25 BR BR112014002060A patent/BR112014002060A2/pt not_active Application Discontinuation
  • 2012-07-25 JP JP2014521983A patent/JP2014523978A/ja active Pending
  • 2012-07-25 EP EP12741250.0A patent/EP2737127A1/fr not_active Withdrawn
  • 2012-07-25 US US14/235,639 patent/US20140166222A1/en not_active Abandoned
  • 2012-07-25 WO PCT/EP2012/003133 patent/WO2013013813A1/fr not_active Ceased

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