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EP2087169A1 - Procédé pour la fabrication d'une bande de matière fibreuse multicouche à partir de fibres cellulosiques - Google Patents

Procédé pour la fabrication d'une bande de matière fibreuse multicouche à partir de fibres cellulosiques

Info

Publication number
EP2087169A1
EP2087169A1 EP07847084A EP07847084A EP2087169A1 EP 2087169 A1 EP2087169 A1 EP 2087169A1 EP 07847084 A EP07847084 A EP 07847084A EP 07847084 A EP07847084 A EP 07847084A EP 2087169 A1 EP2087169 A1 EP 2087169A1
Authority
EP
European Patent Office
Prior art keywords
agent
retention
stream
retention agent
water
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.)
Withdrawn
Application number
EP07847084A
Other languages
German (de)
English (en)
Inventor
Simon Champ
Wolfgang Gaschler
Marc Leduc
Ellen KRÜGER
Christoph Hamers
Hans-Peter Hentze
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.)
BASF SE
Original Assignee
BASF SE
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 BASF SE filed Critical BASF SE
Priority to EP07847084A priority Critical patent/EP2087169A1/fr
Publication of EP2087169A1 publication Critical patent/EP2087169A1/fr
Withdrawn legal-status Critical Current

Links

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
    • 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
    • D21H21/06—Paper forming aids
    • D21H21/10—Retention agents or drainage improvers
    • 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
    • D21F11/02—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines of the Fourdrinier type
    • D21F11/04—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines of the Fourdrinier type paper or board consisting on two or more layers
    • 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
    • D21H17/33—Synthetic macromolecular compounds
    • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H17/37—Polymers of unsaturated acids or derivatives thereof, e.g. polyacrylates
    • 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
    • D21H17/63—Inorganic compounds
    • D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
    • 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
    • D21H21/16—Sizing or water-repelling agents
    • 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
    • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
    • D21H27/30—Multi-ply
    • D21H27/38—Multi-ply at least one of the sheets having a fibrous composition differing from that of other sheets

Definitions

  • the invention relates to a method for producing a multi-layer fibrous web of cellulose fibers by separately feeding at least two different fiber suspensions and water into a multi-layer headbox, wherein they are separated from each other and from the water by separating elements and reach a device after leaving the headbox nozzle orifice a web is formed, wherein the water is guided so that it comes after exiting the nozzle orifice in the form of a layer between two layers of fiber suspensions on the web forming device and thus counteracts a mixing of the different fiber suspensions.
  • a method for producing a multilayer fibrous web from at least two different fiber suspensions is known.
  • the fiber suspensions and water are each fed separately to a multi-layer headbox, wherein they are separated by separating elements and after leaving the nozzle mouth of the headbox on a device on which a web is formed, wherein the water is guided so that it after the Exits the nozzle orifice in the form of a layer between two layers of fiber suspensions on the web forming device and prevents mixing of the various fiber suspensions.
  • the separating elements in the multi-layer headbox are designed so that they are movable in the vertical direction and thus allow in the headbox a change in pressure between the pulp suspensions.
  • 4,388,150 and WO-A-94/05595 disclose a process for the production of paper using a microparticle system, in which case dosed a cationic polymer to the paper stock, then subjecting the mixture to the action of a shear field, then adding bentonite or silica and dewatering the pulp so obtainable without further action of shearing forces.
  • a microparticle system comprising a cationic polymer and a finely divided inorganic component is metered to the pulp after the last shear stage in front of the headbox and then the pulp is dewatered.
  • organic microparticles are known, which may be uncrosslinked or crosslinked and each containing at least 1 wt .-%, but usually at least 5 wt .-% of an ionic comonomer in copolymerized form.
  • the particle size of the uncrosslinked, water-insoluble microparticles is below 60 nm, while it is less than 750 nm for the crosslinked microparticles.
  • the organic microparticles are used in papermaking together with a high molecular weight ionic polymer as a retention aid system, which may optionally additionally contain inorganic microparticles such as bentonite or silica.
  • DE-A-10 2004 063 005 discloses a process for the production of paper, paperboard and paperboard using a microparticle system composed of a cationic polymeric retention agent having a molecular weight of at least 2 million and a finely divided inorganic component.
  • the polymeric retention aid is metered into the stock and the finely divided inorganic component at least two times before or after the addition of the polymeric retention aid, subjecting the stock to at least one shear stage either before or after the addition of the retention agent.
  • Further microparticle systems which are used as retention aids in papermaking are known, for example, from US Pat. No. 6,103,065 and WO-A-2004/015200.
  • the invention has for its object to provide a method for producing multilayer papers with an improved formation available, wherein the mixing of the individual fiber streams during the web forming process does not take place as much as in known methods.
  • the object is achieved with a method for producing a multilayer fibrous web of cellulose fibers by separately feeding at least two different fiber suspensions and water in a Mehrla- genstoffauflaufkasten, wherein they are separated by separating elements from each other and supplied water and after leaving the nozzle orifice of Headbox on a dewatering device on which a multi-layer fibrous web is formed, wherein the water is guided so that it passes after exiting the nozzle orifice in the form of a layer between two layers of fiber suspensions on the web forming device and thus counteracts a mixing of the different fiber suspensions if, in order to improve the retention, drainage and formation, at least one retention agent and / or at least one dehydrating agent in the fiber suspensions and / or in the water supplied d osiert.
  • a retention agent or a dehydrating agent or both products are metered into fiber suspensions.
  • the addition of these agents may occur in the papermaking process prior to shear of the stock, between two shear stages, or after the last shear of the stock.
  • an aqueous solution of at least one retention agent and / or at least one dewatering agent is metered into the stock stream at a location downstream of the last shear stage of the stock and upstream of the headbox mouth.
  • the addition of retention agent and / or dehydrating agent to the paper material is particularly advantageous under turbulent flow of the aqueous formulations of process chemicals. This achieves the most uniform possible distribution of these products in the pulp.
  • the device described in US-B-6,659,636 consists, for example, of a two-component or multi-fluid nozzle through which water recycled from the paper machine and retention agent and / or dehydrating agent are passed into a laminar flowing paper stream.
  • the flow rate of the paper stock flow is, for example, at least 2 m / sec in the case of conventional paper machines and is usually in the range of 3 to 7 m / sec.
  • a method for producing a multilayer fibrous web of cellulosic fibers by separately feeding at least two different fiber suspensions and water into a multi-layer headbox wherein they are separated from each other and from supplied water by separating elements and reach a dewatering device after leaving the headbox nozzle mouth, on which a multilayer fibrous web is formed, wherein the water is guided so that it after leaving the nozzle orifice in the form of a
  • Layer passes between two layers of fiber suspensions on the web forming device and thus counteracts a mixing of the various fiber suspensions, is known from the prior art WO-A-03/048452 known.
  • the flow of the supplied water is guided within the headbox by so-called "blade means" and passes between two streams of pulp suspensions into the dewatering section of the paper machine.
  • the speed of the water flow is adapted to the speed of the fiber streams and is, for example, in the range of 2 to 10 m / sec, preferably 3 to 8 m / sec.
  • the velocity of the water stream separating the fiber streams is preferably from 1 to 25%, most often from 5 to 10%, higher than the velocity of the individual fiber streams.
  • At least two fiber suspensions which are processed into a multilayer fibrous web have a different composition.
  • the middle layer of a three-layer fibrous web may consist of a cheap fibrous material such as waste paper, and the upper and lower side of the fibrous web may consist of a high-quality fibrous web.
  • gene pulp, such as bleached pine sulfate are formed.
  • a further variant of the method according to the invention consists in metering at least two mutually different retention agents into at least two streams of fiber suspensions. These fiber suspensions may be composed of the same or different fibers. In addition, it is possible for at least two streams of fiber suspensions to contain a different concentration of retention aid.
  • an aqueous solution of a retention agent and an aqueous dispersion of at least one filler are metered apart from one another or as a mixture into the paper stock.
  • retention aids and dehydrating agents can also be metered into at least one stream of the water supplied.
  • the retention aid supplied with the water can also be withdrawn as an aqueous solution from a storage vessel or metered separately into the water supplied.
  • Fibers are used in particular when the pulp has a high cationic demand, for example having a COD of from 300 to 30,000, usually from 1000 to 20,000 mg of oxygen / kg of the aqueous phase of the pulp.
  • fixing agents are condensates of dicyandiamide and formaldehyde, condensates of dimethylamine and epichlorohydrin, cationic polyacrylamides having molecular weights Mw 1 000 to 20 000, or hydrolyzed homopolymers and copolymers of N-vinylformamide having a K value of 30 to 150, preferably 60 to 90 (determined according to H. Fikentscher, Cellulosic Chemistry, Vol. 13, 48-64 and 71-74 (1932) in 5% strength by weight aqueous common salt solution at a temperature of 25 ° C. and a polymer concentration of 0.5% by weight) , Fixing agents are used, for example, in an amount of 0.02 to 2 wt .-%, preferably 0.05 to 0.5 wt .-%, based on dry pulp.
  • retention aids which are known from the practice of papermaking or from the literature for this purpose. They are used for example in an amount of 0.01 to 0.3, preferably 0.01 to 0.05 wt .-%, based on dry pulp.
  • the retention agent may, for example, be selected from the group of cationic, anionic, nonionic and amphoteric polymeric organic compounds or a microparticle system.
  • the most common retention aids belong, for example, to the group of the polyacrylamides, the polymethacrylamides, the polymers containing vinylamine units and / or the microparticle systems.
  • Polyacrylamides and polymethyacrylamides can be nonionic, cationic, anionic or amphoteric.
  • Polymers suitable as retention aids have an average molecular weight M w of at least 1 million, preferably at least 2 million and in particular at least 5 million.
  • Nonionic polyacrylamides or polymethacrylamides are prepared, for example, by polymerizing N-vinylformamide, acrylamide and / or methacrylamide.
  • Cationic polyacrylamides are, for example, copolymers prepared by copolymerizing acrylamide and at least one di-C 1 -C 2 -alkylamino-C 2 -C 4 -alkyl (meth) acrylate or a basic acrylamide in the form of the free bases, the salts with organic or inorganic acids or the compounds which are quaternized with alkyl halides or with dimethyl sulfate.
  • Examples of such compounds are dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, dimethylaminopropyl methacrylate, dimethylaminopropyl acrylate, diethylaminopropyl methacrylate, diethylaminopropyl acrylate and / or dimethylaminoethylacrylamide, dimethylaminoethylmethacrylamide, dimethylaminopropylacrylamide, dimethylaminopropylmethacrylamide and / or diallyldimethylammonium chloride.
  • the comonomers mentioned can also be copolymerized with methacrylamide to form cationic polymethacrylamides containing, for example, 5 to 40 mol% of at least one cationic monomer, such as dimethylaminoethyl acrylate or diallyldimethylammonium chloride, in copolymerized form.
  • Cationic polymethacrylamides can be prepared by copolymerizing methacrylamide with at least one of the cationic monomers described above.
  • Other cationic polymers used as retention aids are copolymers of N-vinylformamide and at least one of the abovementioned cationic monomers.
  • Anionic polyacrylamides are obtainable, for example, by copolymerizing acrylamide with at least one ethylenically unsaturated C3- to C5-carboxylic acid, in particular acrylic or methacrylic acid and / or monomers containing sulfonic acid groups, such as vinylsulfonic acid or styrenesulfonic acid and / or a salt of said monomers , Suitable salts are preferably the alkali metal salts, in particular the sodium salts and ammonium salts, into consideration.
  • Anionic polymethacrylamides are prepared in analogy by polymerizing methacrylamide with the monomers having the above acid groups.
  • the anionic polymers contain, for example, copolymerized 1 to 50, preferably 5 to 40 mol% of at least one anionic monomer.
  • the anionic polymeric retention aids also include copolymers which are obtainable by copolymerizing
  • R 1 , R 2 H or C 1 - to C 6 -alkyl
  • the copolymeric anionic compound of this group used is preferably a copolymer which is obtainable by copolymerizing N-vinylformamide, acrylic acid, methacrylic acid and / or their alkali metal or ammonium salts and optionally other monoethylenically unsaturated monomers,
  • (c) contains from 0 to 30 mol% of units of at least one other monoethylenically unsaturated monomer in copolymerized form.
  • the compounds of this group may be modified such that they additionally contain at least one compound (d) in copolymerized form with at least two ethylenically unsaturated double bonds in the molecule.
  • branched copolymers contain, for example, thiols, sec. Alcohols, sulfites, phosphites, hypophosphites, thioacids, aldehydes, etc. (further details can be found, for example, in EP-A-0 438 744, page 5, lines 7-12).
  • the branched copolymers contain, for example
  • Amphoteric polyacrylamides and amphoteric polymethacrylamides each contain units of cationic and of anionic monomers in copolymerized form.
  • An example of this is a copolymer of acrylamide, dimethylaminoethyl acrylate hydrochloride and acrylic acid.
  • Vinylamine-containing polymers are obtainable by hydrolysis of vinylformamide units containing polymers.
  • Polyvinylamines are prepared for example by hydrolysis of homopolymers of N-vinylformamide, wherein the degree of hydrolysis, for example, up to 100%, usually 70 to 95%.
  • High molecular weight copolymers of N-vinylformamide with other ethylenically unsaturated monomers such as vinyl acetate, vinyl propionate, methyl acrylate, Methacrylklaremethy- ester, acrylamide, acrylonitrile and / or methacrylonitrile, can be hydrolyzed to Vinylamineinomme containing polymers and used according to the invention as a retention agent.
  • the polymers containing vinylamine units are cationic.
  • polyDADMAC polydiallyldimethylammonium chlorides
  • branched polyacrylamides which are e.g. can be prepared by copolymerization of acrylamide or methacrylamide with at least one cationic monomer in the presence of small amounts of crosslinkers.
  • polyDADMAC polydiallyldimethylammonium chlorides
  • branched polyacrylamides which are e.g. can be prepared by copolymerization of acrylamide or methacrylamide with at least one cationic monomer in the presence of small amounts of crosslinkers.
  • Such polymers are described, for example, in US-A-5,393,381, WO-A-99/66130 and WO-A-99/63159.
  • cationic retention aids are polyamines having a molecular weight of more than 50,000, modified polyamines grafted with ethyleneimine and optionally crosslinked, polyetheramides, polyvinylimidazoles, polyvinylpyrrolidines, polyvinylimidazolines, polyvinyltetrahydropyrines, poly (dialkylaminoalkylvinylether), poly (dialkylaminoalkyl (meth) acrylates) in protonated or in quaternized form and polyamidoamines from a dicarboxylic acid such as adipic acid and polyalkylenepolyamines such as diethylenetriamine, which are grafted with ethyleneimine and crosslinked with Polyethylenglykoldich- lorhydrinethern according to the teaching of DE-B-24 34 816 or polyamidoamines, with Epichlorohydrin are converted to water-soluble condensation products.
  • Further retention aids are cationic starches, alum and polya
  • microparticle systems made of a polymeric retention agent having a molecular weight M w of at least 1 million, preferably at least 2 million, and a finely divided inorganic or organic component.
  • a polymeric retention agent having a molecular weight M w of at least 1 million, preferably at least 2 million, and a finely divided inorganic or organic component.
  • Such systems are known, cf. US-A-3, 052,595, EP-A-017353, EP-A-223,223, EP-A-0 335 575, EP-A-711,371, WO-A-01/34910, US-A-6,103,065 and DE-A-102 36,252. Both components are typically added separately to the stock during the papermaking process.
  • Suitable organic components of the microparticle system are the above-described polymers, for example retention aids from the group of polymers containing vinylamine units, polymers containing vinylguanidine units, nonionic, cationic and anionic polyacrylamides, polyethyleneimines, ethyleneimine-grafted, crosslinked polyamidoamines, cationic starches and poly-diallyldimethylammonium chlorides ,
  • the polymeric retention aids of the microparticle system are added to the paper stock, for example, in an amount of 0.005 to 0.5% by weight, preferably in an amount of 0.01 to 0.25% by weight, based on dry paper stock.
  • Benetonit, colloidal silicic acid, silicates and / or calcium carbonate may be considered as an inorganic component of the microparticle system.
  • Colloidal silicic acid is to be understood as meaning products based on silicates, for example silica microgel, silical sol, polysilicates, aluminum silicates, boron silicates, polyboron silicates, clay or zeolites.
  • Calcium carbonate can be used, for example, in the form of chalk, ground calcium carbonate or precipitated calcium carbonate as the inorganic component of the microparticle system.
  • Bentonite is generally understood to be phyllosilicates which are swellable in water. These are mainly the clay mineral montmorrillonite as well as similar clay minerals like
  • Nontronite, hectorite, saponite, sauconite, beidellite, allevardite, illite, halloysite, attapulgite and sepiolite are preferably activated before use, ie converted into a water-swellable form in which the phyllosilicates are treated with an aqueous base such as aqueous solutions of caustic soda, potassium hydroxide, soda, potash, ammonia or amines. Bentonite in the form treated with sodium hydroxide solution is preferably used as the inorganic component of the microparticle system.
  • the platelet diameter of the water-dispersed bentonite is in the sodium hydroxide treated form, for example 1 to 2 microns, the thickness of the platelets is about 1 nm.
  • the thickness of the platelets is about 1 nm.
  • Typical bentonites are described, for example, in EP-B-0235893.
  • bentonite is added to the cellulosic suspension, typically in the form of an aqueous bentonite slurry. This bentonite slurry may contain up to 10% by weight of bentonite. Normally, the slurries contain about 3 to 5 wt .-% bentonite.
  • colloidal silica products from the group of silicon-based particles, silica microgels, silica sols, aluminum silicates, borosilicates, polyborosilicates or zeolites can be used. These have a specific surface area of 50 to 1000 m 2 / g and an average particle size distribution of 1 to 250 nm, normally in the range 40 to 100 nm. The production of such components is described, for example, in EP-AO 041 056, EP-AO 185 068 and US-A-5,176,691.
  • Clay or kaolin is a hydrous aluminum silicate with a platelet-like structure.
  • the crystals have a layer structure and an aspect ratio (diameter to thickness ratio) of up to 30: 1.
  • the particle size is e.g. at least 50% smaller than 2 ⁇ m.
  • Carbonates used are preferably natural calcium carbonate (ground calcium carbo- nate, GCC) or precipitated calcium carbonate (PCC).
  • GCC is produced, for example, by grinding and visual processes using grinding aids. It has a particle size of 40 - 95% less than 2 microns, the specific surface area is in the range of 6 - 13 m 2 / g.
  • PCC becomes for example by introducing carbon dioxide into an aqueous calcium hydroxide solution. The average particle size is in the range of 0.03-0.6 ⁇ m.
  • the specific surface area can be greatly influenced by the choice of precipitation conditions. It is in the range of 6 to 13 m 2 / g.
  • the inorganic component of the microparticle system is added to the paper stock in an amount of 0.01 to 2.0% by weight, preferably in an amount of 0.1 to 1.0% by weight, based on dry paper stock.
  • microparticle system also suitable as a microparticle system are combinations of an organic polymer having a molecular weight M w of at least 2 million and a mixture of a finely divided inorganic component and a finely divided organic component, wherein the two components are metered independently of one another either simultaneously or in succession.
  • a suitable finely divided organic component with an anionic charge is described, for example, in WO-A-98/29604.
  • At least one finely divided crosslinked copolymer of acrylamide and at least one monoethylenically unsaturated anionic monomer is preferably used as finely divided, organic component of the microparticle system.
  • microparticle systems are combinations of cationic polymers such as cationic starch and finely divided silica or of cationic polymers such as cationic polyacrylamide and bentonite.
  • flocculants may also be metered into at least one stream of a fiber suspension and / or into at least one stream of the water supplied.
  • flocculants which are effective only at a higher temperature.
  • An example is methyl cellulose as a flocculant is ineffective at about 20 0 C and acts at 75 ° C as a flocculant, see. GV Franks, Journal of Colloid and Interface Science 292, 598-603 (2005).
  • Another example of a thermosensitive flocculant is poly (N-isopropylacrylamide).
  • thermosensitive flocculants can be metered, for example, into at least one stream of the water fed in, which has a temperature in the region in which the flocculant is effective.
  • the stream of pulps may have a temperature in the range of 20 to 45 ° C, while the flow of the feed water may have a temperature in the range of 60 to 75 ° C.
  • PH-sensitive flocculants can also be used in the process according to the invention.
  • An example of such a flocculant is the polysaccharide chitosan.
  • Suitable dehydrating agents are preferably polymers containing ethyleneimine units. Such polymers are already listed above with the cationic retention agents. They act both as retention aids and as draining agents. Since the dehydrating effect of this class of compounds is more pronounced than the retenierenden effect, they are referred to in the present context as a dehydrating agent.
  • Polyethyleneimines which are obtainable by polymerizing ethyleneimine in aqueous solution in the presence of acidic catalysts such as mineral acids or halogen compounds such as methylene chloride, carbon tetrachloride, ethylene chloride or tetrachloroethane, as well as crosslinked condensation products of a polyamidoamine and one grafted with ethyleneimine, belong in particular to this class of compounds dicarboxylic acid.
  • acidic catalysts such as mineral acids or halogen compounds
  • halogen compounds such as methylene chloride, carbon tetrachloride, ethylene chloride or tetrachloroethane
  • crosslinked condensation products of a polyamidoamine and one grafted with ethyleneimine belong in particular to this class of compounds dicarboxylic acid.
  • Such products are sold under the trademark Polymin® by BASF, Ludwigshafen. They are used in papermaking, for example, in an amount of at least 0.01% by weight, usually in the range from 0.1
  • At least one stream of a fiber suspension is metered with a polyacrylamide and / or a polymer comprising vinylamine units and a polymer containing ethyleneimine units in a stream of another fiber suspension.
  • Vinylamine-containing polymers are Vinylamine-containing polymers, microparticle systems and mixtures thereof,
  • a dehydrating agent from the group consisting of Ethyleniminiseren containing polymers and / or a retention agent from the group of vinylamine units containing polymers, cationic, anionic, nonionic and amphoteric polyacrylamides, Polymethacrylamides and their mixtures, and
  • (C) in the stream of fiber suspension which forms the underside of the fibrous web a retention agent from the group of polyacrylamides, polymethacrylamides, polymers containing vinylamine units, the microparticle systems and mixtures thereof.
  • Paper webs having an improved formation are obtained, for example, by using a higher concentration of retention agent in the stream forming the middle fibrous web when producing a three-layer fibrous web than in the streams forming the top and bottom of the fibrous web .
  • the amount of retention agent used for the middle layer of a three-layer fibrous web is, for example,> 0.01% by weight, usually 0.015 to 0.3% by weight, based on dry paper stock.
  • the amounts of retention agent are usually ⁇ 0.01 wt .-%, for example in the range of 0.001 to 0.009 wt .-%, based on dry fiber.
  • a retention agent or a filler takes place with the aid of the supplied water.
  • at least one retention agent and at least one thickener are metered into the stream of the water supplied.
  • Suitable thickeners are, for example, high molecular weight polyacrylamides or high molecular weight polycarboxylic acids having molecular weights M w of at least 1 million, preferably at least three million.
  • the thickeners are preferably crosslinked polyacrylamides or crosslinked polycarboxylic acids which swell very strongly in an aqueous medium.
  • An example of a known thickener is a crosslinked polyacrylic acid.
  • Suitable crosslinkers are, for example, methylenebisacrylamide, glycol diacrylate, butanediol diacrylate, butanediol dimethacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, pentaerythritol triallyl ether or triallylamine.
  • the amounts of thickening agent added to the water are, for example, from 0.001 to 10% by weight, preferably from 0.01 to 1% by weight. This achieves an increase in the viscosity of the water, which reduces the risk of mixing different fiber streams during the dewatering process.
  • the paper stock preferably the thin stock, and / or the stream of the supplied water contains at least one suspended filler.
  • Suitable fillers are the finely divided inorganic substances customarily used in papermaking, for example titanium dioxide, ground calcium carbonate (marble), precipitated calcium carbonate, chalk, talc, montmorillonite, dolomite or clay. Filler may, for example, in an amount up to 40 wt .-%, usually in the range of 5 to 30 wt .-%, each on dry pulp, are used.
  • the fillers are used, for example, in the form of an aqueous, pumpable slurry containing a dispersant such as polyacrylic acid having a molecular weight M w of 5,000 to 12,000.
  • the fillers may also be added by adding to the pulp in the preparation of the pulp.
  • the finely divided inorganic fillers generally lead to an increase in the basis weight of the filler-containing paper compared to a filler-free paper.
  • thermally expandable microparticles directly to the paper stock or by metering according to the invention as an aqueous suspension together with a retention agent and / or a dehydrating agent at a point in the paper stock stream Last shear stage of the pulp and before the nozzle mouth of the headbox is.
  • metering an aqueous suspension of thermally expandable microparticles into the stream of the water fed in, which counteracts a mixing of the fiber streams.
  • the microparticles are used, for example, in an amount of from 2 to 50% by weight, preferably from 5 to 45% by weight, based on dry paper stock.
  • Thermally expandable microparticles are known. They have, for example, a mean particle diameter of 17 to 35 microns. They are prepared by polymerizing ethylenically unsaturated monomers in the presence of a blowing agent and optionally further substances such as silica, bentonite, clay, organic suspending agents such as methyl cellulose, carboxymethyl cellulose or polyvinyl alcohol, starch or oxides and hydroxides of aluminum, calcium, magnesium or barium.
  • the blowing agent content of the microparticles is 17 to 40 wt .-%, see. US-A-2006/0102307.
  • the microparticles described therein have a shell of a polymer of vinylidene chloride, acrylonitrile and methyl methacrylate.
  • the effect of the dehydrating agents can be enhanced by using them together with at least one surfactant.
  • Alkoxylation products of alcohols or amines are preferably suitable as surface-active agents.
  • An example of this is Sursol® VL (BASF Aktiengesellschaft, Ludwigshafen).
  • the amounts of surfactants are for example 0.01 to 10 wt .-%, based on dry pulp.
  • Further agents of this category are quaternized alkanolamine fatty acid esters which are described, for example, in US Pat. No. 2006/0196624. or polyamine amides as described, for example, in Nordic Pulp and Paper Research Journal 2003, 18, 188-193.
  • At least one retention agent is used in combination with a sizing agent.
  • Suitable engine sizes are preferably reactive sizes, in particular C 12 -C 22 alkyl ketene dimers, C 5 -C 22 -alkyl and / or C 5 -C 22 -alkenyl succinic anhydrides, C 12 -C 36 -alkyl isocyanates or mixtures of the abovementioned compounds.
  • resin glue can be used as a mass sizing agent.
  • the aqueous reactive size dispersions are stabilized, for example, with the aid of cationic starch, cf.
  • the sizing agents employed are both cationic and in particular anionic aqueous dispersions of at least one C 12 -C 22 -alkyldiketene. Such dispersions are known, for example, from WO-A-00/23551, pages 2 to 12.
  • the reactive sizing agents are usually heated to a temperature above their melting point and then emulsified in water under the action of shear forces.
  • Liquid alkenylsuccinic anhydrides can already be emulsified at room temperature.
  • emulsifying use is made e.g. the usual homogenizers.
  • dispersants are used.
  • at least one anionic dispersant is used for the preparation of anionic sizing dispersions, for example a dispersant from the group of the condensation products
  • the anionic dispersants may be in the form of the free acids, the alkali metal, alkaline earth metal and / or ammonium salts.
  • the ammonium salts can be derived from both ammonia and from primary, secondary and tertiary amines, for example, the ammonium salts of dimethylamine, trimethylamine, hexylamine, cyclohexylamine, dicyclohexylamine, ethanolamine, diethanolamine and triethanolamine are.
  • the condensation products described above are known and commercially available. They are prepared by condensing said components, it being possible to use the corresponding alkali metal, alkaline earth metal or ammonium salts instead of the free acids.
  • Suitable catalysts for the condensation are, for example, acids such as sulfuric acid, p-toluenesulfonic acid and phosphoric acid.
  • Naphthalenesulfonic acid or its alkali metal salts are with Formaldehyde preferably in a molar ratio of 1: 0.1 to 1: 2 and usually in a molar ratio of 1: 0.5 to 1: 1 condensed.
  • the molar ratio for the production of condensates of phenol, phenolsulfonic acid and formaldehyde is also in the range given above, using any mixtures of phenol and phenolsulfonic acid instead of naphthalenesulfonic acid in the condensation with formaldehyde.
  • phenolsulfonic acid instead of phenolsulfonic acid, it is also possible to use the alkali metal and ammonium salts of phenolsulfonic acid.
  • the condensation of the abovementioned starting materials may optionally be carried out additionally in the presence of urea.
  • urea based on naphthalenesulfonic acid or on the mixture of phenol and phenolsulfonic acid, 0.1 to 5 moles of urea are used per mole of naphthalenesulfonic acid or per mole of the mixture of phenol and phenolsulfonic acid.
  • the condensation products have, for example, molar masses in the range from 800 to 100,000, preferably 1,000 to 30,000 and in particular from 4,000 to 25,000.
  • anionic dispersants are salts which are obtained, for example, by neutralizing the condensation products with lithium hydroxide, sodium hydroxide, Potassium hydroxide or ammonia receives.
  • the pH of the salts is, for example, in the range of 7 to 10.
  • amphiphilic copolymers are amphiphilic copolymers
  • hydrophobic monoethylenically unsaturated monomers and (ii) hydrophilic monomers having an anionic group, such as monoethylenically unsaturated carboxylic acids, monoethylenically unsaturated sulfonic acids, monoethylenically unsaturated phosphonic acids or mixtures thereof.
  • Suitable hydrophobic monoethylenically unsaturated monomers (i) are, for example, olefins having 2 to 150 carbon atoms, styrene, ⁇ -methylstyrene, ethylstyrene, 4-methylstyrene, acrylonitrile, methacrylonitrile, esters of monoethylenically unsaturated C 3 to C 5.
  • Carboxylic acids and monohydric alcohols amides of acrylic acid or methacrylic acid with Cr to C24-alkylamines, vinyl esters of saturated monocarboxylic acids having 2 to 24 carbon atoms, diesters of maleic acid or fumaric acid with monohydric C to C24 alcohols, vinyl ethers of alcohols having 3 to 24 C atoms or mixtures of the named compounds.
  • amphiphilic copolymers contain, as hydrophilic monomers (ii), for example C 3 - to C 10 -monoethylenically unsaturated carboxylic acids or their anhydrides, 2-acrylamido-2-methylpropanesulfonic acid, vinylsulfonic acid, styrenesulfonic acid, vinylphosphonic acid, salts of said monomers or mixtures thereof as hydrophilic monomers with an anionic one Group polymerized.
  • hydrophilic monomers (ii) for example C 3 - to C 10 -monoethylenically unsaturated carboxylic acids or their anhydrides, 2-acrylamido-2-methylpropanesulfonic acid, vinylsulfonic acid, styrenesulfonic acid, vinylphosphonic acid, salts of said monomers or mixtures thereof as hydrophilic monomers with an anionic one Group polymerized.
  • Particularly preferred are aqueous sizing agent dispersions containing anionic dispersant amphiphilic cop
  • maleic acid acrylic acid, methacrylic acid, half esters of maleic acid and alcohols having 1 to 25 carbon atoms or alkoxylation of such alcohols, hemiamides of maleic acid, salts of said monomers or mixtures of these compounds as hydrophilic monomers having an anionic group
  • copolymerized form contained in copolymerized form and have a molecular weight M w of 1 500 to 100 000.
  • the anionic dispersants used are preferably copolymers of maleic anhydride with C 4 - to C 12 -olefins, particularly preferably C 2 -olefins, such as octene-1 and diisobutene. Most preferred is diisobutene.
  • the molar ratio between maleic anhydride and olefin is for example in the range 0.9: 1 to 3: 1, preferably from 0.95: 1 to 1, 5: 1.
  • These copolymers are preferably used in hydrolyzed form as aqueous solution or dispersions, wherein the anhydride group is open and the carboxyl groups are preferably partially or completely neutralized.
  • alkali metal bases such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate
  • alkaline earth salts such as calcium hydroxide, calcium carbonate, magnesium hydroxide, ammonia, primary, secondary or tertiary amines, such as triethylamine, triethanolamine, diethanolamine, ethanolamine, morpholine etc.
  • amphiphilic copolymers are not sufficiently soluble in water in the form of the free acid, they are used in the form of water-soluble salts, for example using the corresponding alkali metal, alkaline earth metal and ammonium salts.
  • the molecular weight M w of the amphiphilic copolymers is, for example, 800 to 250,000, usually 1,000 to 100,000 and is preferably in the range from 3,000 to 20,000, in particular from 1,500 to 10,000.
  • the acid numbers of the amphiphilic copolymers are, for example, 50 to 500, preferably 150 to 300 mg KOH / g polymer.
  • amphiphilic copolymers are used, for example, in amounts of 0.05 to 20, preferably 0.5 to 10 wt .-%, based on the reactive sizing agent, as an anionic dispersant for the preparation of sizing dispersions.
  • the amphiphilic copolymers are used in amounts of 0.1 to 2, in particular 0.6 to 1 wt .-%, based on the sizing agent to be dispersed.
  • aqueous anionic sizing dispersions can be present, for example, an aqueous solution of at least one condensation product or at least one amphiphilic copolymer and disperse therein the sizing agent at temperatures of for example 20 to 100, preferably 40 to 90 0 C.
  • the sizing agent is preferably added in the form of a melt and dispersed with vigorous stirring or shearing. The resulting dispersion is cooled in each case.
  • aqueous, anionically adjusted sizing dispersions which contain 6 to 65% by weight of an alkyldiketene or 0.1 to 65% by weight of an alkenylsuccinic anhydride dispersed as sizing agent.
  • Further preferred sizing agent dispersions contain from 25 to 60% by weight of an alkyldiketene sizing agent and from 0.1 to 5.0% by weight of an amphiphilic copolymer
  • Such highly concentrated size dispersions have a relatively low viscosity, for example in the range of 20 to 100 mPas (measured with a Brookfield viscometer and a temperature of 2O 0 C).
  • the pH is, for example, from 2 to 8, and is preferably in the range of from 3 to 4. This gives aqueous, anionically adjusted sizing agent dispersions having an average size of sizing agents in the range of 0.1 to 3, preferably 0.5 to 1, 5 microns.
  • the anionically dispersed reactive sizing agents may additionally contain at least one cationic dispersant, but the amount of cationic dispersant must be selected such that the dispersion as a whole carries an anionic charge.
  • Preferred cationic dispersant is cationic starch.
  • the addition of a retention agent and / or a filler takes place in combination with a sizing agent and / or a solidifying agent with the aid of the supplied water.
  • a retention agent, a fixing agent and a sizing agent and / or a solidifying agent and optionally at least one thickener are metered into the stream of the water supplied.
  • the addition of a binder alone or in combination with a filler, a retention agent, a fixing agent, a sizing agent and / or a solidifying agent is preferably carried out with the aid of the supplied water or it is metered into the pulp.
  • at least one binder and optionally a filler, a retention agent, a fixing agent, a sizing agent, a solidifying agent and optionally at least one thickener are preferably metered into the stream of the water supplied.
  • these additives can be mixed in the desired ratio in a storage container and conveyed therefrom into the nozzle chamber of the headbox.
  • Binders for example, cause better binding of fillers to the paper fibers and, when metered into the fiber streams forming the outer layers of the paper, improve the printability of the paper. With the aid of the binders it is also possible to improve the barrier properties of paper, e.g. against the penetration of fats, oils and water and against the passage of gases, in particular oxygen or air.
  • Suitable synthetic binders are polymers which contain at least 40% by weight of so-called main monomers selected from C 1 -C 20 -alkyl (meth) acrylates, vinyl esters of saturated carboxylic acids containing up to 20 C atoms, vinylaromatics up to 20 C atoms, ethylenically unsaturated nitriles, vinyl halides, vinyl ethers of alcohols containing 1 to 10 C atoms, aliphatic hydrocarbons having 2 to 8 C atoms and one or two double bonds or mixtures of these monomers.
  • main monomers selected from C 1 -C 20 -alkyl (meth) acrylates, vinyl esters of saturated carboxylic acids containing up to 20 C atoms, vinylaromatics up to 20 C atoms, ethylenically unsaturated nitriles, vinyl halides, vinyl ethers of alcohols containing 1 to 10 C atoms, aliphatic hydrocarbons having 2 to 8 C atoms
  • Suitable synthetic polymers are, in particular, polymers obtainable by free-radical polymerization of ethylenically unsaturated compounds (monomers).
  • the binder is preferably a polymer which consists of at least 40% by weight, preferably at least 60% by weight, particularly preferably at least 80% by weight, of so-called main monomers.
  • the main monomers are selected from C 1 -C 20 -alkyl (meth) acrylates, vinyl esters of saturated carboxylic acids containing up to 20 C atoms, vinylaromatics having up to 20 C atoms, ethylenically unsaturated nitriles, vinyl halides, vinyl ethers of 1 to 10 C-containing alcohols, aliphatic hydrocarbons having 2 to 8 carbon atoms and one or two double bonds or mixtures of these monomers.
  • (meth) acrylic acid alkyl ester having a Ci-Cio-alkyl radical such as methyl methacrylate, methyl acrylate, n-butyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate.
  • Ci-Cio-alkyl radical such as methyl methacrylate, methyl acrylate, n-butyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate.
  • mixtures of (meth) acrylic acid alkyl esters are also suitable.
  • Vinyl esters of carboxylic acids having 1 to 20 carbon atoms are, for. As vinyl laurate, vinyl stearate, vinyl propionate, vinyl versatate and vinyl acetate.
  • Suitable vinylaromatic compounds are vinyltoluene, ⁇ - and p-methylstyrene, ⁇ -butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene and preferably styrene.
  • nitriles are acrylonitrile and methacrylonitrile.
  • the vinyl halides are chloro, fluoro or bromo substituted ethylenically unsaturated compounds, preferably vinyl chloride and vinylidene chloride.
  • vinyl ethers are, for. As vinyl methyl ether or vinyl isobutyl ether. Vinyl ether is preferably from 1 to 4 C-containing alcohols.
  • hydrocarbons having 2 to 8 carbon atoms and one or two olefinic double bonds may be mentioned ethylene, propylene, butadiene, isoprene and chloroprene.
  • Preferred main monomers are C 1 -C 10 -alkyl (meth) acrylates and mixtures of the alkyl (meth) acrylates with vinylaromatics, especially styrene (polymers with these main monomers are collectively called polyacrylates for short) or, alternatively, hydrocarbons having 2 double bonds, in particular butadiene, or Mixtures of such hydrocarbons with vinyl aromatics, in particular styrene (polymers with these main monomers are collectively called polybutadienes for short).
  • the ratio z. B between 10:90 to 90:10, in particular 20:80 to 80:20.
  • the polymer may contain monomers having at least one acid group (short acid monomer), z.
  • monomers with carboxylic acid sulfonic acid or phosphonic acid groups.
  • Called z. For example, acrylic acid, methacrylic acid, itaconic acid, maleic acid or fumaric acid.
  • hydroxyl-containing monomers in particular Ci-Cio-hydroxyalkyl (meth) acrylates, (meth) acrylamide. Accordingly, particularly preferred polymers are synthesized in the case of polybutadienes
  • wt .-% preferably 0 to 10 wt .-% acid monomer and 0 to 20 wt .-%, preferably 0 to 10 wt .-% further monomers.
  • Both the polybutadienes and the polyacrylates preferably contain acid monomers as comonomers, preferably in an amount of 1 to 5 wt .-%.
  • the maximum amount of the above aliphatic hydrocarbons in the polybuadienes and the alkyl (meth) acrylates in the polyacrylates is reduced accordingly by the minimum amount of the acid monomers.
  • the polymers are prepared in a preferred embodiment by emulsion polymerization, it is therefore an emulsion polymer.
  • the polymers can z. B. also be prepared by solution polymerization and subsequent dispersion of the polymer solution in water.
  • ionic and / or nonionic emulsifiers and / or protective colloids or stabilizers are used as surface-active compounds.
  • the surface-active substance is used, for example, in amounts of from 0.1 to 10% by weight, based on the monomers to be polymerized.
  • Water-soluble initiators for the emulsion polymerization are z.
  • ammonium and alkali metal salts of peroxodisulfuric z.
  • sodium peroxodisulfate, hydrogen peroxide or organic peroxides z.
  • the amount of initiators is generally 0.1 to 10 wt .-%, preferably 0.5 to 5 wt .-%, based on the monomers to be polymerized. It is also possible to use a plurality of different initiators in the emulsion polymerization.
  • polymerization regulators can be used, for. B. in amounts of 0 to 0.8 parts by weight, based on 100 parts by weight of the monomers to be polymerized, by which the molecular weight is reduced.
  • Suitable z. B. Compounds with a thiol group such as tert-butylmercaptan, Thioglykolklareethylacrylester, mercaptoethanol, mercaptopropyltrimethoxysilane or tert-dodecylmercaptan.
  • the emulsion is usually carried out at 30 to 130 0 C, preferably 50 to 9O 0 C.
  • the polymerization medium may consist of water only, as well as mixtures of water and thus miscible liquids such as methanol. Preferably, only water is used.
  • the emulsion polymerization can be carried out both as a batch process and in the form of a feed process, including a stepwise or gradient procedure.
  • the feed process in which one submits a portion of the polymerization, heated to the polymerization, polymerized and then the rest of the polymerization, usually over several spatially separate feeds, one or more of which monomers in pure or in emulsified form, continuously , gradually or with the addition of a concentration gradient while maintaining the polymerization of the polymerization zone supplies.
  • the polymerization it is also possible, for example for the purpose of better adjustment of the particle size, to introduce a polymer seed.
  • the manner in which the initiator is added to the polymerization vessel in the course of the free radical aqueous emulsion polymerization is known to one of ordinary skill in the art. It can be introduced both completely into the polymerization vessel, or used continuously or in stages according to its consumption in the course of the free radical aqueous emulsion polymerization. In particular, this depends on the chemical nature of the initiator system as well as on the polymerisation temperature. Preferably, a part is initially charged and the remainder supplied according to the consumption of the polymerization.
  • aqueous dispersions of the polymer are generally obtained with solids contents of 15 to 75 wt .-%, preferably from 40 to 75 wt .-%.
  • Suitable binders are in particular mixtures of various binders, eg. As well as mixtures of synthetic and natural polymers.
  • Aqueous polymer dispersions are preferably used as binders, which are composed of at least 60 wt .-% of butadiene or mixtures of butadiene and styrene or aqueous dispersions of polymers containing at least 60 wt .-% d- to C20-alkyl (meth) acrylates or Mixtures of d- to C2o-alkyl (meth) acrylates in copolymerized form with styrene.
  • Suitable binders are polymers containing N-vinylformamide and / or vinylamine units, which have an average molecular weight M w of at least 10,000. These polymers can be in the form of an aqueous dispersion or as a solution in water. They are prepared, for example, by polymerizing N-vinylformamide alone or in the presence of at least one other nonionic, cationic and / or anionic monomer. The homopolymers and copolymers of N-vinylformamide which can be prepared in this way can be hydrolyzed in a polymer-analogous reaction with elimination of formyl groups from the copolymerized vinylformamide units to form amino groups.
  • the hydrolysis is preferably carried out in an aqueous medium in the presence of at least one acid such as hydrochloric acid or sulfuric acid, enzymatically or in the presence of bases such as sodium hydroxide or potassium hydroxide.
  • the vinylformamide units may be wholly or even partially hydrolyzed. For example, in a complete hydrolysis of homopolymers of N-vinylformamide, polyvinylamines are obtained.
  • Suitable anionic monomers are, for example, monomers containing acid groups. Examples thereof are acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, vinylphosphonic acid, acrylamido-2-methylpropanesulfonic acid, styrenesulfonic acid, allylacetic acid, crotonic acid and ethacrylic acid.
  • the anionic monomers can be used in the polymerization in the form of the free acids or in partially or completely neutralized with alkali metal, alkaline earth metal and / or ammonium bases form.
  • the sodium salts or potassium salts of the acids are preferably suitable.
  • N-vinylformamide can also be copolymerized with cationic monomers such as dialkylaminoalkyl (meth) acrylates and / or diallyldimethylammonium chloride.
  • the basic monomers are preferably used in the form of the salts with mineral acids or in form partially or fully quaternized with alkyl halides or with dimethyl sulfate.
  • N-vinylformamide with anionic and / or cationic monomers may optionally be additionally used nonionic monomers such as methyl acrylate, ethyl acrylate, methyl methacrylate, vinyl acetate, acrylamide and / or methacrylamide. Both the hydrolyzed cationic and the nonhydrolyzed cationic copolymers can be used as binders for the modification of inorganic pigments.
  • amphoteric polymers which are obtainable, for example, by copolymerization of N-vinylformamide, dimethylaminoethyl acrylate methochloride and acrylic acid, or which are formed by complete or partial hydrolysis of the vinylformamide units of these copolymers.
  • the polymers containing vinylformamide and / or vinylamine units which are used to modify pigments preferably have an average molecular weight M w of at least 20,000.
  • M w average molecular weight of at least 20,000.
  • the average molar masses of the copolymers are in the range from 30,000 to 5 million, in particular from 50 000 to 2 million.
  • the molecular weights are determined, for example, with the aid of static light scattering at pH 7.6 in a 10 mmolar aqueous saline solution.
  • the ethylene copolymer waxes described above have, for example, a melt flow rate (MFR) in the range of 1 to 50 g / 10 min, preferably 5 to 20 g / 10 min, more preferably 7 to 15 g / 10 min, measured at 160 ° C. and a load of 325 g according to EN ISO 1 133.
  • MFR melt flow rate
  • Its acid value is usually 100 to 300 mg KOH / g wax, preferably 1 15 to 230 mg KOH / g wax, determined to DIN 53402.
  • the melting ranges of the ethylene copolymer are, for example, in the range of 60 to 110 0 C, preferably in the range of 65 to 90 ° C, determined by DSC in accordance with DIN 51,007th
  • the melting ranges of the ethylene copolymer may be wide and, a temperature raturintervall of at least 7 to a maximum of 20 0 C is preferred to have at least 10 0 C and at most 15 ° C.
  • the melting points of the ethylene copolymer waxes may also have a small fluctuation range and be in a temperature range of less than 2 ° C, preferably less than 1 ° C, determined according to DIN 51007.
  • the density of the waxes is usually 0.89 to 1, 10 g / cm 3 , preferably 0.92 to 0.99 g / cm 3 , determined according to DIN 53479.
  • the ethylene copolymer waxes are e.g. alternating copolymers or block copolymers or, preferably, random copolymers.
  • Ethylene copolymer waxes of ethylene and ethylenically unsaturated carboxylic acids and optionally ethylenically unsaturated carboxylic acid esters can advantageously be prepared by free-radically initiated copolymerization under high-pressure conditions, for example in high-pressure autoclaves equipped with an agitator or in high-pressure tubular reactors. Production in high-pressure autoclaves equipped with a stirrer is preferred.
  • Such high-pressure autoclaves are known per se, a description can be found in Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, keywords: Waxes, Vol. A 28, p. 146 et seq., Verlag Chemie, Weinheim, Basel, Cambridge, New York, Tokyo , 1996.
  • Suitable pressure conditions for the polymerization are 500 to 4000 bar, preferably 1500 to 2500 bar. Conditions of this type are also referred to below as high pressure.
  • the reaction temperatures are in the range from 170 to 300 ° C., preferably in the range from 195 to 280 ° C.
  • the polymerization can also be carried out in the presence of a regulator. The above-mentioned waxes are described in detail, for example, in WO-A-04/108601, page 2, line 38 to page 12, line 10.
  • the addition of an unstabilized engine sizing agent takes place alone or in combination with a filler, a retention agent, a fixing agent and / or a solidifying agent with the aid of the water supplied.
  • at least one unstabilized engine sizing agent is metered into the stream of water fed in, and optionally a filler, a retention agent, a fixing agent, a solidifying agent and at least one thickener.
  • Unstabilized engine sizing agents are to be understood as meaning the massing agents described above which contain no or very small amounts of stabilizers. If the metered-in emulsifier dispersion is metered into the stream of the water fed in directly after emulsification according to the above-described variant of the process according to the invention, the bulk emulsifying agent can be emulsified on site.
  • aqueous dispersions of a size sizing agent may optionally be used together with a cationic synthetic polymer acting as fixer and promoter, wherein fixer and promoter are metered into the stock in admixture with at least one size sizing agent or separately therefrom.
  • the dosage is usually in the thin material.
  • engine sizing agents and optionally promoters in combination with a retention agent are metered into the stock stream at a point downstream of the last shear stage of the stock and in front of the nozzle head of the headbox.
  • the cationic polymers used as fixing agents and promoters for engine lubricants can be metered into the stock before or after the last shear stage, for example.
  • cationic polymers of this type are polymers containing vinylamine units, polymers containing vinylguanidine units, polyethyleneimines, polyamidoamines grafted with ethyleneimine and / or polydiallyldimethylammonium chlorides.
  • the amount of fixing agent is for example 0.02 to 2.0, preferably 0.05 to 0.5 wt .-%, based on dry pulp.
  • At least one retention agent is used in combination with a solidifying agent for paper.
  • solidifying agents for paper are, for example, urea-formaldehyde resins which, in addition to the wet strength, also increase the dry strength of the paper (cf EP-AO 123 196 and US-A-3,275,605), melamine-formaldehyde resins (cf. B-10 90 078) or other commercial products eg polyamidoamines crosslinked with epichlorohydrin (see the trademarks Luresin®, BASF Aktiengesellschaft, Ludwigshafen).
  • Suitable cellulose fibers are, for example, wood pulp and all annual plants.
  • Wood pulp includes, for example, groundwood, thermomechanical pulp (TMP), chemothermomechanical pulp (CTMP), pressure groundwood, semi-pulp, high yield pulp, and refiner mechanical pulp (RMP), as well as recovered paper.
  • pulps used in bleached or unbleached forms are suitable. such as sulphate, sulphite and soda pulps as well as recovered paper fibers.
  • unbleached pulps also referred to as unbleached kraft pulp, are used.
  • the fibers mentioned can be used alone or in a mixture. Particularly preferred is the use of kraft pulp as well as TMP and CTMP.
  • the pH of the cellulose fiber slurry is, for example, 4 to 8, preferably 6 to 8.
  • the pulp concentration, which is dewatered in the paper machine, is at most 2% by weight and is usually in the range of 0.5 to 1 , 0 wt .-%, based on dry pulp.
  • the paper stock is in each case processed according to the invention into a multilayer fibrous web by dewatering it on a wire with formation of a web.
  • the webs thus produced are dried. Dewatering of the stock and drying of the webs are part of the papermaking process, which is performed continuously.
  • the process according to the invention it is possible, for example, to produce papers which are composed of 2, 3, 4, 5 or more layers. Preference is given to three-layered papers. In this case, it is possible to inexpensively produce good quality papers by using cheap fibers for the middle layer and qualitatively better fibers for the top and bottom of the three-layered paper.
  • bleached fibers such as birch sulphate and / or pine sulphate bleached fibers may be used to form the top and bottom of a three-ply paper, while recycled paper, TMP and / or wood pulp fibers may be considered for the middle layer of the three-ply paper ,
  • the multilayer papers produced according to the invention are suitable, for example, as printing and writing papers, copying papers, inkjet papers, cardboard and paperboard, as well as for packaging on liquids and the production of folding boxes and corrugated cardboard as well as cardboard.

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Abstract

L'invention concerne un procédé pour la fabrication d'une bande de matière fibreuse multicouche à partir de fibres cellulosiques grâce à l'alimentation séparée d'au moins deux suspensions fibreuses différentes et d'eau dans un caisson de passage de substance multicouche, dans lequel elles sont séparées de l'eau et l'une de l'autre par des éléments de séparation, et parvient à un dispositif, sur lequel une bande est formée, après avoir quitté le nez de filière du caisson de passage de substance, l'eau étant amenée de sorte de manière à parvenir en aval de la sortie du nez de filière sous la forme d'une couche entre deux couches de suspensions fibreuses sur le dispositif de formation de bande, et empèche ainsi le mélange des diverses suspensions fibreuses, au moins un agent de rétention et/ou au moins un agent déshydratant étant dosé dans les suspensions fibreuses et/ou dans l'eau ajoutée.
EP07847084A 2006-10-31 2007-10-29 Procédé pour la fabrication d'une bande de matière fibreuse multicouche à partir de fibres cellulosiques Withdrawn EP2087169A1 (fr)

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EP07847084A EP2087169A1 (fr) 2006-10-31 2007-10-29 Procédé pour la fabrication d'une bande de matière fibreuse multicouche à partir de fibres cellulosiques

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EP06123288 2006-10-31
PCT/EP2007/061631 WO2008052970A1 (fr) 2006-10-31 2007-10-29 Procédé pour la fabrication d'une bande de matière fibreuse multicouche à partir de fibres cellulosiques
EP07847084A EP2087169A1 (fr) 2006-10-31 2007-10-29 Procédé pour la fabrication d'une bande de matière fibreuse multicouche à partir de fibres cellulosiques

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US8357220B2 (en) 2008-11-07 2013-01-22 Hollingsworth & Vose Company Multi-phase filter medium
FI121890B (fi) * 2009-06-08 2011-05-31 Upm Kymmene Corp Uudentyyppinen paperi ja menetelmä sen valmistamiseksi
FI125818B (fi) * 2009-06-08 2016-02-29 Upm Kymmene Corp Menetelmä paperin valmistamiseksi
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