EP1831459B1 - Method for the production of paper, cardboard and card - Google Patents

Method for the production of paper, cardboard and card Download PDF

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Publication number
EP1831459B1
EP1831459B1 EP05817729.6A EP05817729A EP1831459B1 EP 1831459 B1 EP1831459 B1 EP 1831459B1 EP 05817729 A EP05817729 A EP 05817729A EP 1831459 B1 EP1831459 B1 EP 1831459B1
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EP
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Prior art keywords
retention aid
process according
finely divided
inorganic component
divided inorganic
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EP05817729.6A
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German (de)
French (fr)
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EP1831459A1 (en
Inventor
Oliver Koch
Frank Prechtl
Rainer Blum
Detlef Kannengiesser
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BASF SE
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BASF SE
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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
    • 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
    • D21H17/375—Poly(meth)acrylamide
    • 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
    • D21H17/46—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H17/54—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen
    • D21H17/55—Polyamides; Polyaminoamides; Polyester-amides
    • 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
    • D21H17/46—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H17/54—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen
    • D21H17/56—Polyamines; Polyimines; Polyester-imides
    • 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
    • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
    • D21H23/02—Processes or apparatus for adding material to the pulp or to the paper characterised by the manner in which substances are added
    • D21H23/04—Addition to the pulp; After-treatment of added substances in the pulp
    • D21H23/06—Controlling the addition
    • D21H23/14—Controlling the addition by selecting point of addition or time of contact between components
    • D21H23/18—Addition at a location where shear forces are avoided before sheet-forming, e.g. after pulp beating or refining

Definitions

  • the invention relates to a process for the production of paper, paperboard and cardboard by adding a microparticle system of a polymeric retention agent having a molecular weight M w of at least 2 million and a finely divided inorganic component to a pulp having a maximum density of 20 g / l and dewatering the Textilstoffs, wherein the pulp before or after the addition of the cationic retention agent is subjected to at least one shear stage.
  • EP-A-0 223 223 is a method for the production of paper and cardboard by dehydration of a paper material known, wherein first added to a paper stock with a concentration of 2.5 to 5 wt .-% bentonite, then diluted the paper stock, a highly cationic polymer with a charge density of min 4 meq / g is added and finally a high molecular weight polymer based on acrylamide is added and the resulting pulp is dewatered after thorough mixing.
  • an essentially linear synthetic cationic polymer having a molecular weight of more than 500,000 in an amount of more than 0.03% by weight, based on dry paper stock, of an aqueous pulp suspension is first metered into the mixture then the action of a shear field, wherein the first formed flakes are cut into microflakes carrying a cationic charge, then dosed bentonite and dewatered the pulp thus obtained without further action of shear forces.
  • EP-A-0 335 575 describes a papermaking process in which a polymeric cationic fixing agent and then a water-soluble cationic polymer are metered into a pulp, the pulp thus obtained is then subjected to at least one shear stage and then flocculated by the addition of bentonite.
  • EP-A-0 885 328 describes a process for the production of paper, wherein initially dosed to an aqueous pulp suspension, a cationic polymer, then subjecting the mixture to the action of a shear field, then adding an activated bentonite and dewatering the pulp thus obtained.
  • EP-A-0 910 701 describes a process for the production of paper and board, wherein the paper pulp successively added a low molecular weight or medium molecular weight cationic polymer based on polyethyleneimine or polyvinylamine and then with a high molecular weight cationic polymer such as polyacrylamide, polyvinylamine or cationic starch. After this pulp has been subjected to at least one shear stage, it is flocculated by addition of bentonite and the pulp is dewatered.
  • WO-A-01/34910 there is described a process for producing paper in which a polysaccharide or a synthetic, high molecular weight polymer is metered into the pulp suspension. Subsequently, a mechanical shear of the pulp must take place.
  • the reflocculation is carried out by adding an inorganic component such as silica, bentonite or clay and a water-soluble polymer.
  • From the US-A-6,103,065 discloses a method of improving the retention and dewatering of paper stocks by adding a cationic polymer having a molecular weight of 100,000 to 2 million and a charge density of more than 4.0 meq./g to a pulp after the last shearing, simultaneously or thereafter adding a polymer having a molecular weight of at least 2 million and a charge density of less than 4.0 meq./g and then metering in bentonite. It is not necessary in this method to shear the stock after the addition of the polymers. After addition of the polymers and the bentonite, the pulp can be dewatered without further action of shearing forces.
  • From the DE-A-102 36 252 is a method for producing paper, paperboard and cardboard by shearing a stock, adding a microparticle system of a cationic polymer and a finely divided inorganic component to the pulp after the last shear stage before the headbox, dewatering the stock to form sheets and drying the sheets one as cationic Polymers of the microparticle system cationic polyacrylamides, vinylamine units containing polymers and / or polydiallyldimethylammonium chloride having an average molecular weight M w of at least 500 000 daltons and a charge density of at most 4.0 meq./g used.
  • US 6719881 describes a microparticle system for use as a retention and drainage aid in the manufacture of alkaline and acid paper products containing a high molecular weight flocculant polymer, an acid colloid and a coagulant or flocculant having an average molecular weight.
  • the acid colloid comprises an aqueous solution of the water-soluble polymer or copolymer of melamine-aldehyde, preferably melamine-formaldehyde, and is present in an amount ranging from 0.0005% by weight to 0.5% by weight, based on the dry weight of Solids in the substance entry, available.
  • EP 1039026 discloses the production of paper by the formation of a thick stock cellulose suspension, flocculation of the thick stock by adding a polymer having a relatively high molecular weight and a relatively low cationic charge density, diluting the flocculated thick stock to form a thin stock, and then dewatering the thin stock; to form a paper sheet.
  • the coagulant is added to the slurry prior to dewatering and the best results are achieved by adding the coagulant followed by anionic colloidal material, such as bentonite.
  • the present invention has for its object to provide a further method for the production of paper, cardboard and paperboard using a microparticle system, which gives better retention and papers having an improved formation compared to the known methods.
  • the object is achieved with a method for producing paper, cardboard and cardboard by adding a microparticle system consisting of at least one cationic polymeric retention agent having a molecular weight M w of at least 2 million and a finely divided inorganic component to a pulp having a consistency of at most 20 g / l and dewatering the Textilstoffs, wherein the pulp before or after the addition of the retention agent is subjected to at least one shear stage, when dosed the retention agent at least two locations in the pulp and the finely divided inorganic component before or after the addition of the retention agent or between two dosing agents for retention aids, wherein one uses as finely divided inorganic component of the microparticle system at least one bentonite, colloidal silica, silicates, calcium carbonate or mixtures thereof.
  • all paper qualities can be produced, for example cardboard, single or multilayer carton, single or multi-layer liners, corrugating medium, papers for newspaper printing, so-called medium-fine writing and printing papers, natural gravure papers and lightweight base papers.
  • TMP thermo-mechanical pulp
  • CMP chemo-thermo-mechanical fabric
  • PGW pressure ground
  • wood pulp and sulfite and sulfate pulp emanate.
  • the pulps can be short fiber as well as long fiber.
  • fibers recovered from recovered paper alone or in admixture with other fibers for the manufacture of paper, board and cardboard Preferably, wood-free grades are produced by the process according to the invention, which yield highly white paper products.
  • the papers may optionally contain up to 40 wt .-%, usually 5 to 35 wt .-% fillers.
  • Suitable fillers are e.g. Titanium dioxide, natural and pre-painted chalk, talc, kaolin, satin white, calcium sulfate, barium sulfate, clay or alumina.
  • the production of the paper products takes place continuously. Usually, one starts from a thick material having, for example, a consistency in the range of 3 to 6 wt .-%.
  • the thick material is diluted to a substance density of at most 20 g / l and processed according to the invention to the respective desired paper product.
  • the consistency is for example 3 to 15 g / l, preferably 5 to 12 g / l and is usually in the range of 6 to 10 g / l.
  • the microparticle system according to the invention consists of at least one polymeric retention agent having a molecular weight M w of at least 2 million and a finely divided anionic component.
  • the retention aid may be cationic, anionic, amphoteric or nonionic.
  • the average molecular weight M w of the polymeric retention aids is at least 2 million daltons, preferably at least 3 million, and is usually in the range of, for example, 3.5 million to 15 million.
  • the charge density of the polymers in question is for example at most 4.0 meq./g.
  • cationic polyacrylamides having an average molecular weight M w of at least 5 million daltons and a charge density of 0.1 to 3.5 meq./g and polyvinylamines obtainable by hydrolysis of vinylformamide units containing polymers and having an average molecular weight of at least Have 2 million daltons.
  • the polyvinylamines are preferably prepared 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, methyl methacrylate, acrylamide, acrylonitrile and / or methacrylonitrile, can be hydrolyzed to vinylamine units containing polymers and used according to the invention.
  • all polyvinylamines having a molecular weight M w of at least 2 million can be used according to the invention, which are obtainable by hydrolysis of vinylformamide units-containing polymers, the degree of hydrolysis of the vinylformamide units being 0.5 to 100 mol%.
  • the preparation of homopolymers and copolymers of N-vinylformamide is known. For example, in the US 6,132,558 , Column 2, line 36 to column 5, line 25 described in detail. The statements made there are hereby incorporated by reference into the disclosure content of the present application.
  • Cationic polyacrylamides are, for example, copolymers prepared by copolymerizing acrylamide and at least one di-C 1 -bisC 2 -alkylamino-C 2 -bisC 4 -alkyl (meth) acrylate or a basic acrylamide in the form of the free bases, the salts with organic or inorganic acids or the alkyl halides quaternized compounds are available.
  • 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 also be used as the polymeric retention aid of the microparticle system.
  • polymers containing cationic polyacrylamides and vinylamine units may be the references cited in the prior art, such as EP-A-0 910 701 and US-A-6,103,065 be removed.
  • Such polymers are commercial products.
  • Branched polymers which can be prepared, for example, by copolymerization of acrylamide or methacrylamide with at least one cationic monomer in the presence of small amounts of crosslinking agents are described, for example, in the references cited in the prior art US Patent No. 5,393,381 .
  • WO-A-99/66130 and WO-A-99/63159 described.
  • polystyrene resins are poly (N-vinylformamides).
  • N-vinylformamides are prepared by polymerizing N-vinylformamide into homopolymers or by copolymerizing N-vinylformamide together with at least one other ethylenically unsaturated monomer.
  • the vinylformamide units of these polymers are not hydrolysed, in contrast to the preparation of polymers containing vinylamine units.
  • the copolymers can be cationic, anionic or amphoteric.
  • Cationic polymers are obtained, for example, by copolymerizing N-vinylformamide with at least one of the basic monomers mentioned in the copolymerization of acrylamide.
  • Anionic polymers of N-vinylformamide are obtainable by copolymerizing N-vinylformamide in the presence of at least one acid monoethylenically unsaturated monomer.
  • Such comonomers are, for example, monoethylenically unsaturated C 3 -bis C 5 carboxylic acids, acrylamido-2-methylpropanesulfonic acid, styrenesulfonic acid or sulfopropyl acrylate.
  • the acidic monomers can also be used in completely neutralized with alkali metal, alkaline earth metal and / or ammonium bases in the copolymerization with N-vinylformamide.
  • copolymers mentioned contain units of anionic or cationic monomers, for example, in amounts of 0.5 to 50, preferably 5 to 40 mol% copolymerized.
  • Copolymers of N-vinylformamide can also be amphoteric if they contain units of anionic and cationic monoethylenically unsaturated monomers in copolymerized form.
  • nonionic polyacrylamides and nonionic polymethacrylamides obtainable by polymerizing acrylamide and / or methacrylamide, as well as anionic polyacrylamides and anionic polymethacrylamides.
  • the anionic poly (meth) acrylamides are obtainable, for example, by polymerizing acrylamide or methacrylamide with at least one anionic monomer.
  • Suitable anionic monomers are, for example, monoethylenically unsaturated C 3 -C 5 -carboxylic acids, such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, vinylacetic acid or ethacrylic acid, and vinylphosphonic acid, styrenesulfonic acid, acrylamido-2-methylpropanesulfonic acid, sulfopropyl acrylate or sulfopropyl methacrylate and the alkali metal, alkaline earth metal and ammonium salts of the acid group-containing monomers into consideration.
  • monoethylenically unsaturated C 3 -C 5 -carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, vinylacetic acid or ethacrylic acid, and vinylphosphonic acid, styrenesulfonic acid, acrylamido-2-methylpropanesulfonic acid
  • the anionic copolymers contain, for example, 1 to 50 mol%, preferably 5 to 40 mol% of at least one anionic monomer in copolymerized form.
  • amphoteric copolymers of acrylamide and methacrylamide can be used as the polymeric retention aid of the microparticle system.
  • Such copolymers are obtainable by copolymerizing acrylamide or methacrylamide in the presence of at least one anionic and at least one cationic ethylenically unsaturated monomer.
  • Suitable cationic polymeric retention aids of the microparticle system are polydiallyldimethylammonium chlorides (PolyDADMAC) with an average molecular weight of at least 2 million daltons. Polymers of this type are commercial products.
  • the polymeric retention aids of the microparticle system are added to the paper stock 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.
  • Suitable inorganic components of the microparticle system are, for example, bentonite, colloidal silicic acid, silicates and / or calcium carbonate.
  • Colloidal silicic acid is to be understood as meaning products based on silicates, for example silica microgel, silical sol, polysilicates, aluminum silicates, boron silicates, polyborosilicates, clay or zeolites.
  • Calcium carbonate can be used, for example, in the form of chalk, ground calcium carbonate or precipitated calcium carbonate can be used as the inorganic component of the microparticle system.
  • Bentonite is generally understood to be phyllosilicates which are swellable in water.
  • clay mineral montmorillonite and similar clay minerals such as nontronite, hectorite, saponite, sauconite, beidellite, allevardite, illite, halloysite, attapulgite and sepiolite.
  • These phyllosilicates 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 or those bentonites which are already obtained in the sodium form, so-called Wyoming bentonites, are preferably used as the inorganic component of the microparticle system.
  • the platelet diameter of the water-dispersed bentonite in the sodium hydroxide-treated form is, for example, at most 1 to 2 ⁇ m, the thickness of the platelets is approximately 1 nm.
  • the bentonite has a specific surface area of 60 to 800 m 2 / g .
  • Typical bentonites are used in the EP-B-0235893 described.
  • 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 1500 m 2 / g and an average particle size distribution of 1-250 nm, normally in the range 5-100 nm.
  • the preparation of such components is described, for example, in US Pat EP-A-0 041 056 .
  • 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.
  • the carbonates used are preferably natural calcium carbonate (ground calcium carbonate, 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 is made by passing 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 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 stock.
  • the aqueous fiber slurry is subjected to at least one shear stage. It goes through at least one cleaning, mixing and / or pumping stage.
  • the shearing of the pulp (thin material) can be done for example in a pulper, classifier or in a refiner.
  • the retention agent is metered according to the invention in at least two places in the thin and the finely divided inorganic component before or after the addition of the retention agent or between two dosing sites for retention aid.
  • the process can be carried out, for example, by adding the retention agent after the last shear stage to at least two successive points and then metering the finely divided inorganic component.
  • the retention agent after the last shear stage is added to at least two points which have the same distance from the shear stage, and then dosed the finely divided inorganic component.
  • the process can also be carried out by adding the retention agent before the last shear stage at at least two points, which are arranged in a plane perpendicular to the stock flow or behind one another, and by metering the finely divided inorganic component after the last shear stage.
  • At least one retention agent to the thin material, to subject the system to shear, then to add at least one retention agent (identical or preferably different to the first-dosed retention agent) and then to add at least one finely divided inorganic component.
  • the process according to the invention it is possible first to meter 25 to 75% by weight of the total retention agent before the last shear stage and the remaining portion of the retention agent and then to add the finely divided inorganic component or to meter it first before the last Scherimpl the finely divided inorganic component and 25 to 75 wt .-% of the retention agent and after the last shear stage the remaining portion of the retention agent.
  • the finely divided inorganic component is metered in each case before the last shearing stage, followed by the retention agent at least two in a plane perpendicular to the first Textilstoffstrom or at successively arranged locations.
  • the flow rate of the paper pulp stream is, for example, at least 2 m / sec in most paper machines and is usually in the range of 3 to 7 m / sec.
  • the dosage of the retention agent can be made for example by means of single or multi-fluid nozzles in the paper stream. This achieves a rapid distribution of the retention agent in the pulp.
  • the distance between the center of the metering points of the retention agent is, for example, at least 20 cm in successive addition of retention agent.
  • the distance between the center of a metering point for retention agent and the center of a metering point for the finely divided inorganic component for example, also at least 20 cm.
  • the retention sites for retention aids can also be arranged in a plane perpendicular to the stock flow.
  • the distance between the center of the dosing points of the retention agent is preferably at least 50 cm and the distance between the center of a dosing point for retention agent and the center of a dosing point for the finely divided inorganic component at least 50 cm.
  • the distance between the center of the dosing points of the retention agent is in most cases, for example in the range of 50 cm to 15 m, wherein the distance between the center of a dosing agent for retention agent and the center of a dosing point for the finely divided inorganic component, for. at least 50 cm.
  • the location of the addition points is preferably such that the distance between the center of the dosing points of the retention agent is 50 cm to 10 m and the distance between the center of a dosing point for retention agent and the center of a dosing point for the finely divided inorganic component 50 cm to 5 m.
  • the retention agents can also be metered into the paper stock stream at 3 to 5 positions arranged one behind the other. Likewise, it is possible to meter the finely divided inorganic component of the retention agent system into the stock stream at at least two successive locations.
  • the customary amounts of process chemicals customarily used in papermaking for example fixatives, dry and wet strength agents, engine sizes, biocides and / or dyes.
  • the paper stock is dewatered on a sieve with formation of sheets. The leaves thus produced are dried. Dehydrating the pulp and Drying of the sheets are part of the papermaking process and are carried out continuously in the art.
  • the process according to the invention gives papers having a surprisingly good formation and, compared to known microparticle processes, has an improved filler and fines retention.
  • the First Pass Retention was determined by determining the ratio of the solids content in the white water to the solids content in the headbox. The information is given in percent.
  • the first pass ash retention (FPAR) was determined analogously to the FPR, but only the ash content was considered.
  • the formation was measured with a TECHPAP 2D Lab Formation Sensor from Tecpap).
  • the dimensionless FX value is given in the table. The lower this value, the better the formation of the tested paper.
  • Mikroflocc® XFB As an inorganic component of the microparticle system, Mikroflocc® XFB was used.
  • Mikrofloc® XFB is a bentonite powder activated by treatment with aqueous caustic soda. It is usually converted on site in a 3-5% suspension.
  • the following examples and comparative examples were carried out on a GAP Former test paper machine. From a wood-free, bleached pulp was first prepared a pulp with a consistency of 8 g / l and 20% calcium carbonate as a filler, which in the examples and in the comparative examples in each case to a wood-free writing and printing paper having a basis weight of 80 g / m 2 was processed.
  • the paper machine contained the following arrangement of mixing and shearing units: mixing vessel, dilution, deaerator, screen and headbox. One ton of paper was produced per hour. The addition (amount and metering point) of retention aid and finely divided inorganic component was varied as indicated in the examples and comparative examples. The results obtained in each case are given in the table.
  • 650 g / t Polymin 215 (the term "650 g / t" means that 650 g Polymin® 215 were used per ton of produced paper) were added in 2 doses to 350 g / t and 300 g / t with a distance of the dosing of 300 cm in each case before screen and then 2500 g / t of Microfloc® XFB after screen fed to the paper stock described above.
  • Example 1 was repeated with the sole exception that the retention agent (650 g / t Polymin 215) was metered in at a single site 400 cm before screen.
  • Example 2 was repeated with the sole exception that the retention agent (450 g / t Polymin 215) was metered in at a single point.

Description

Die Erfindung betrifft ein Verfahren zur Herstellung von Papier, Pappe und Karton durch Zugabe eines Mikropartikelsystems aus einem polymeren Retentionsmittel mit einer Molmasse Mw von mindestens 2 Millionen und einer feinteiligen anorganischen Komponente zu einem Papierstoff mit einer Stoffdichte von höchstens 20 g/l und Entwässern des Papierstoffs, wobei der Papierstoff vor oder nach der Zugabe des kationischen Retentionsmittels mindestens einer Scherstufe unterworfen wird.The invention relates to a process for the production of paper, paperboard and cardboard by adding a microparticle system of a polymeric retention agent having a molecular weight M w of at least 2 million and a finely divided inorganic component to a pulp having a maximum density of 20 g / l and dewatering the Papierstoffs, wherein the pulp before or after the addition of the cationic retention agent is subjected to at least one shear stage.

Die Verwendung von Kombinationen aus nichtionischen oder anionischen Polymeren und Bentonit als Retentionsmittel bei der Herstellung von Papier ist beispielsweise aus der US-A-3,052,595 und der EP-A-0 017 353 bekannt.The use of combinations of nonionic or anionic polymers and bentonite as retention aids in the production of paper is known, for example, from US Pat US-A-3,052,595 and the EP-A-0 017 353 known.

Aus der EP-A-0 223 223 ist ein Verfahren zur Herstellung von Papier und Karton durch Entwässerung eines Papierstoffs bekannt, wobei man zu einem Papierstoff mit einer Stoffkonzentration von 2,5 bis 5 Gew.-% zuerst Bentonit zusetzt, danach den Papierstoff verdünnt, ein hochkationisches Polymer mit einer Ladungsdichte von mind. 4 meq/g zusetzt und schließlich ein hochmolekulares Polymer auf Basis Acrylamid zusetzt und die so erhaltene Pulpe nach der Durchmischung entwässert.From the EP-A-0 223 223 is a method for the production of paper and cardboard by dehydration of a paper material known, wherein first added to a paper stock with a concentration of 2.5 to 5 wt .-% bentonite, then diluted the paper stock, a highly cationic polymer with a charge density of min 4 meq / g is added and finally a high molecular weight polymer based on acrylamide is added and the resulting pulp is dewatered after thorough mixing.

Nach dem aus der EP-A-0 235 893 bekannten Verfahren zur Herstellung von Papier dosiert man zu einer wässrigen Faserstoffsuspension zunächst ein im wesentlichen lineares synthetisches kationisches Polymer mit einer Molmasse von mehr als 500 000 in einer Menge von mehr als 0,03 Gew.-%, bezogen auf trockenen Papierstoff, unterwirft die Mischung dann der Einwirkung eines Scherfeldes, wobei die zunächst entstandenen Flocken in Mikroflocken zerteilt werden, die eine kationische Ladung tragen, dosiert dann Bentonit und entwässert die so erhaltene Pulpe ohne weitere Einwirkung von Scherkräften.After the out of the EP-A-0 235 893 In known processes for the production of paper, an essentially linear synthetic cationic polymer having a molecular weight of more than 500,000 in an amount of more than 0.03% by weight, based on dry paper stock, of an aqueous pulp suspension is first metered into the mixture then the action of a shear field, wherein the first formed flakes are cut into microflakes carrying a cationic charge, then dosed bentonite and dewatered the pulp thus obtained without further action of shear forces.

EP-A-0 335 575 beschreibt ein Papierherstellverfahren, wobei man zu einer Pulpe zunächst ein polymeres kationisches Fixiermittel und anschließend ein wasserlösliches kationisches Polymer dosiert, die so erhaltene Pulpe dann mindestens einer Scherstufe unterwirft und danach durch Zugabe von Bentonit flockt. EP-A-0 335 575 describes a papermaking process in which a polymeric cationic fixing agent and then a water-soluble cationic polymer are metered into a pulp, the pulp thus obtained is then subjected to at least one shear stage and then flocculated by the addition of bentonite.

In der EP-A-0 885 328 wird ein Verfahren zur Herstellung von Papier beschrieben, wobei man zu einer wässrigen Faserstoffsuspension zunächst ein kationisches Polymer dosiert, die Mischung dann der Einwirkung eines Scherfeldes unterwirft, anschließend eine aktivierte Bentonitdispersion zugibt und die so erhaltene Pulpe entwässert.In the EP-A-0 885 328 describes a process for the production of paper, wherein initially dosed to an aqueous pulp suspension, a cationic polymer, then subjecting the mixture to the action of a shear field, then adding an activated bentonite and dewatering the pulp thus obtained.

Aus der EP-A 0 711 371 ist ein weiteres Verfahren zur Herstellung von Papier bekannt. Bei diesem Verfahren wird ein synthetisches, kationisches, hochmolekulares Polymer zu einer Dickstoff-Cellulose-Suspension gegeben. Nach dem Verdünnen des flockulierten Dickstoffs wird vor dem Entwässern ein Koagulationsmittel, das aus einem anorganischen Koagulationsmittel und/oder einem zweiten, niedermolekularen und hochkationischen wasserlöslichen Polymer besteht, zugegeben.From the EP-A 0 711 371 Another method for producing paper is known. In this process, a synthetic, cationic, high molecular weight polymer added to a thick-matter cellulose suspension. After dilution of the flocculated thick stock, a coagulant consisting of an inorganic coagulant and / or a second, low molecular weight and highly cationic water soluble polymer is added prior to dewatering.

In der EP-A-0 910 701 wird ein Verfahren zur Herstellung von Papier und Karton beschrieben, wobei man zur Papierpulpe nacheinander ein niedrigmolekulares oder mittelmolekulares kationisches Polymer auf Basis Polyethylenimin oder Polyvinylamin und anschließend mit ein hochmolekulares kationisches Polymer wie Polyacrylamid, Polyvinylamin oder kationische Stärke zusetzt. Nachdem diese Pulpe mindestens einer Scherstufe unterworfen wurde, wird sie durch Zugabe von Bentonit geflockt und der Papierstoff entwässert.In the EP-A-0 910 701 describes a process for the production of paper and board, wherein the paper pulp successively added a low molecular weight or medium molecular weight cationic polymer based on polyethyleneimine or polyvinylamine and then with a high molecular weight cationic polymer such as polyacrylamide, polyvinylamine or cationic starch. After this pulp has been subjected to at least one shear stage, it is flocculated by addition of bentonite and the pulp is dewatered.

Aus der EP-A-0 608 986 ist bekannt, dass man bei der Papierherstellung ein kationisches Retentionsmittel zum Dickstoff dosiert. Ein weiteres Verfahren zur Herstellung von Papier und Karton ist aus der US-A-5,393,381 , der WO-A-99/66130 und der WO-A-99/63159 bekannt, wobei man ebenfalls ein Mikropartikelsystem aus einem kationischen Polymer und Bentonit verwendet. Als kationisches Polymer wird ein wasserlösliches, verzweigtes Polyacrylamid eingesetzt.From the EP-A-0 608 986 It is known that in the papermaking process, a cationic retention agent is added to the thick matter. Another method for the production of paper and cardboard is from the US Patent No. 5,393,381 , of the WO-A-99/66130 and the WO-A-99/63159 in which a microparticle system composed of a cationic polymer and bentonite is also used. The cationic polymer used is a water-soluble, branched polyacrylamide.

In der WO-A-01/34910 wird ein Verfahren zur Herstellung von Papier beschrieben, bei dem zu der Papierstoffsuspension ein Polysaccharid oder ein synthetisches, hochmolekulares Polymer dosiert wird. Anschließend muß eine mechanische Scherung des Papierstoffs erfolgen. Die Reflockulation erfolgt durch Zugabe einer anorganischen Komponente wie Kieselsäure, Bentonit oder Clay und eines wasserlöslichen Polymers.In the WO-A-01/34910 there is described a process for producing paper in which a polysaccharide or a synthetic, high molecular weight polymer is metered into the pulp suspension. Subsequently, a mechanical shear of the pulp must take place. The reflocculation is carried out by adding an inorganic component such as silica, bentonite or clay and a water-soluble polymer.

Aus der US-A-6,103,065 ist ein Verfahren zur Verbesserung der Retention und der Entwässerung von Papierstoffen bekannt, wobei man zu einem Papierstoff nach dem letzten Scheren ein kationisches Polymer mit einer Molmasse von 100 000 bis 2 Millionen und einer Ladungsdichte von mehr als 4,0 meq./g zusetzt, gleichzeitig oder danach ein Polymer mit einer Molmasse von mindestens 2 Millionen und einer Ladungsdichte von weniger als 4,0 meq./g zugibt und danach Bentonit dosiert. Es ist bei diesem Verfahren nicht erforderlich, den Papierstoff nach der Zugabe der Polymeren einer Scherung zu unterwerfen. Nach Zugabe der Polymeren und des Bentonits kann die Pulpe ohne weitere Einwirkung von Scherkräften unter Blattbildung entwässert werden.From the US-A-6,103,065 discloses a method of improving the retention and dewatering of paper stocks by adding a cationic polymer having a molecular weight of 100,000 to 2 million and a charge density of more than 4.0 meq./g to a pulp after the last shearing, simultaneously or thereafter adding a polymer having a molecular weight of at least 2 million and a charge density of less than 4.0 meq./g and then metering in bentonite. It is not necessary in this method to shear the stock after the addition of the polymers. After addition of the polymers and the bentonite, the pulp can be dewatered without further action of shearing forces.

Aus der DE-A-102 36 252 ist ein Verfahren zur Herstellung von Papier, Pappe und Karton durch Scheren eines Papierstoffs, Zugabe eines Mikropartikelsystems aus einem kationischen Polymeren und einer feinteiligen anorganischen Komponente zum Papierstoff nach der letzten Scherstufe vor dem Stoffauflauf, Entwässern des Papierstoffs unter Blattbildung und Trocknen der Blätter bekannt, wobei man als kationische Polymere des Mikropartikelsystems kationische Polyacrylamide, Vinylamineinheiten enthaltende Polymere und/oder Polydiallyldimethylammoniumchlorid mit einer mittleren Molmasse Mw von jeweils mindestens 500 000 Dalton und einer Ladungsdichte von jeweils höchstens 4,0 meq./g einsetzt.From the DE-A-102 36 252 is a method for producing paper, paperboard and cardboard by shearing a stock, adding a microparticle system of a cationic polymer and a finely divided inorganic component to the pulp after the last shear stage before the headbox, dewatering the stock to form sheets and drying the sheets one as cationic Polymers of the microparticle system cationic polyacrylamides, vinylamine units containing polymers and / or polydiallyldimethylammonium chloride having an average molecular weight M w of at least 500 000 daltons and a charge density of at most 4.0 meq./g used.

US 6719881 beschreibt ein Mikropartikelsystem zur Verwendung als Retentions- und Entwässerungshilfsmittel bei der Herstellung von alkalischen und sauren Papierprodukten , die ein hochmolekulares Flockulierungsmittel-Polymer, ein_ Säure-Kolloid und ein Koagulans oder Flockulierungsmittel mit einem mittleren Molekulargewicht enthalten. Das Säurekolloid umfasst eine wässrige Lösung des wasserlöslichen Polymers oder Copolymers aus Melamin-Aldehyd, vorzugsweise Melamin-Formaldehyd, und ist in einer Menge im Bereich von 0,0005 Gew.-% bis 0,5 Gew.-%, bezogen auf das Trockengewicht der Feststoffe im Stoffeintrag, vorhanden. US 6719881 describes a microparticle system for use as a retention and drainage aid in the manufacture of alkaline and acid paper products containing a high molecular weight flocculant polymer, an acid colloid and a coagulant or flocculant having an average molecular weight. The acid colloid comprises an aqueous solution of the water-soluble polymer or copolymer of melamine-aldehyde, preferably melamine-formaldehyde, and is present in an amount ranging from 0.0005% by weight to 0.5% by weight, based on the dry weight of Solids in the substance entry, available.

EP 1039026 offenbart die Herstellung von Papier durch die Bildung einer Dickstoff-Zellulose-Suspension, Ausflockung des Dickstoffes durch Zugabe eines Polymers mit einem relativ hohen Molekulargewicht und einer relativ niedrigen kationischen Ladungsdichte, Verdünnung des ausgeflockten Dickstoffes, um Dünnstoff zu bilden, und dann Entwässern des Dünnstoffes, um ein Papierblatt zu bilden. Gewöhnlich wird das Koagulationsmittel vor dem Entwässern zu dem Dünnstoff zugegeben und die besten Ergebnisse werden durch Hinzufügen des Koagulationsmittels gefolgt von anionischem kolloidalen Material, wie Bentonit, erreicht. EP 1039026 discloses the production of paper by the formation of a thick stock cellulose suspension, flocculation of the thick stock by adding a polymer having a relatively high molecular weight and a relatively low cationic charge density, diluting the flocculated thick stock to form a thin stock, and then dewatering the thin stock; to form a paper sheet. Usually, the coagulant is added to the slurry prior to dewatering and the best results are achieved by adding the coagulant followed by anionic colloidal material, such as bentonite.

Bei den bekannten Papierhersteilverfahren, bei denen man ein Mikropartikelsystem als Retentionsmittel verwendet, benötigt man größere Mengen an Polymer und Bentonit. Diejenigen Verfahren, die zwingend die Mitverwendung von kationischen Polymeren mit einer Ladungsdichte von mehr als 4,0 erfordern, ergeben Papiere, die zur Vergilbung neigen. Die bisher bekannten Mikropartikelverfahren zur Papierherstellung haben außerdem den Nachteil, dass sie den heutzutage geforderten Ansprüchen an Formation und Füllstoff- bzw. Feinstoffretention nicht gerecht werden.In the known papermaking processes in which a microparticle system is used as a retention agent, larger amounts of polymer and bentonite are required. Those processes which necessarily require the co-use of cationic polymers with a charge density of more than 4.0 give papers which tend to yellow. The previously known microparticle processes for papermaking also have the disadvantage that they do not meet today's demands on formation and Füllstoff- or fines retention.

Der vorliegenden Erfindung liegt die Aufgabe zugrunde, ein weiteres Verfahren zur Herstellung von Papier, Pappe und Karton unter Verwendung eines Mikropartikelsystems zur Verfügung zu stellen, wobei man im Vergleich zu den bekannten Verfahren eine bessere Retention und Papiere erhält, die eine verbesserte Formation aufweisen.The present invention has for its object to provide a further method for the production of paper, cardboard and paperboard using a microparticle system, which gives better retention and papers having an improved formation compared to the known methods.

Die Aufgabe wird erfindungsgemäß gelöst mit einem Verfahren zur Herstellung von Papier, Pappe und Karton durch Zugabe eines Mikropartikelsystems bestehend aus mindestens einem kationischen polymeren Retentionsmittel mit einer Molmasse Mw von mindestens 2 Millionen und einer feinteiligen anorganischen Komponente zu einem Papierstoff mit einer Stoffdichte von höchstens 20 g/l und Entwässern des Papierstoffs, wobei der Papierstoff vor oder nach der Zugabe des Retentionsmittels mindestens einer Scherstufe unterworfen wird, wenn man das Retentionsmittel an mindestens zwei Stellen in den Papierstoff und die feinteilige anorganische Komponente vor oder nach der Zugabe der Retentionsmittel oder zwischen zwei Dosierstellen für Retentionsmittel dosiert, wobei man als feinteilige anorganische Komponente des Mikropartikelsystems mindestens einen Bentonit, kolloidale Kieselsäure, Silikate, Calciumcarbonat oder deren Mischungen einsetzt.The object is achieved with a method for producing paper, cardboard and cardboard by adding a microparticle system consisting of at least one cationic polymeric retention agent having a molecular weight M w of at least 2 million and a finely divided inorganic component to a pulp having a consistency of at most 20 g / l and dewatering the Papierstoffs, wherein the pulp before or after the addition of the retention agent is subjected to at least one shear stage, when dosed the retention agent at least two locations in the pulp and the finely divided inorganic component before or after the addition of the retention agent or between two dosing agents for retention aids, wherein one uses as finely divided inorganic component of the microparticle system at least one bentonite, colloidal silica, silicates, calcium carbonate or mixtures thereof.

Nach dem erfindungsgemäßen Verfahren können sämtliche Papierqualitäten hergestellt werden, z.B. Karton, ein- oder mehrlagiger Faltschachtelkarton, ein- oder mehrlagiger Liner, Wellenstoff, Papiere für den Zeitungsdruck, sogenannte mittelfeine Schreib- und Druckpapiere, Naturtiefdruckpapiere und leichtgewichtige Streichrohpapiere. Um solche Papiere herzustellen, kann man beispielsweise von Holzschliff, thermomechanischem Stoff (TMP), chemo-thermomechanischem Stoff (CTMP), Druckschliff (PGW), Holzstoff sowie Sulfit- und Sulfatzellstoff ausgehen. Die Zellstoffe können sowohl kurzfaserig als auch langfaserig sein. Es ist jedoch auch möglich, aus Altpapier zurückgewonnene Fasern allein oder in Mischung mit anderen Fasern für die Herstellung von Papier, Pappe und Karton einzusetzen. Vorzugsweise werden nach dem erfindungsgemäßen Verfahren holzfreie Qualitäten hergestellt, die hochweiße Papierprodukte ergeben.By the method according to the invention, all paper qualities can be produced, for example cardboard, single or multilayer carton, single or multi-layer liners, corrugating medium, papers for newspaper printing, so-called medium-fine writing and printing papers, natural gravure papers and lightweight base papers. To produce such papers, you can, for example, from wood pulp, thermo-mechanical pulp (TMP), chemo-thermo-mechanical fabric (CTMP), pressure ground (PGW), wood pulp and sulfite and sulfate pulp emanate. The pulps can be short fiber as well as long fiber. However, it is also possible to use fibers recovered from recovered paper alone or in admixture with other fibers for the manufacture of paper, board and cardboard. Preferably, wood-free grades are produced by the process according to the invention, which yield highly white paper products.

Die Papiere können gegebenenfalls bis zu 40 Gew.-%, meistens 5 bis 35 Gew.-% Füllstoffe enthalten. Geeignete Füllstoffe sind z.B. Titandioxid, natürliche und pränzipitierte Kreide, Talkum, Kaolin, Satinweiß, Calciumsulfat, Bariumsulfat, Clay oder Aluminiumoxid.The papers may optionally contain up to 40 wt .-%, usually 5 to 35 wt .-% fillers. Suitable fillers are e.g. Titanium dioxide, natural and pre-painted chalk, talc, kaolin, satin white, calcium sulfate, barium sulfate, clay or alumina.

Die Herstellung der Papierprodukte erfolgt kontinuierlich. Üblicherweise geht man von einem Dickstoff aus, der beispielsweise eine Stoffdichte in dem Bereich von 3 bis 6 Gew.-% hat. Der Dickstoff wird auf eine Stoffdichte von höchstens 20 g/l verdünnt und erfindungsgemäß zu dem jeweils gewünschten Papierprodukt verarbeitet. Die Stoffdichte beträgt beispielsweise 3 bis 15 g/l, vorzugsweise 5 bis 12 g/l und liegt meistens in dem Bereich von 6 bis 10 g/l.The production of the paper products takes place continuously. Usually, one starts from a thick material having, for example, a consistency in the range of 3 to 6 wt .-%. The thick material is diluted to a substance density of at most 20 g / l and processed according to the invention to the respective desired paper product. The consistency is for example 3 to 15 g / l, preferably 5 to 12 g / l and is usually in the range of 6 to 10 g / l.

Das Mikropartikelsystem besteht erfindungsgemäß aus mindestens einem polymeren Retentionsmittel mit einer Molmasse Mw von mindestens 2 Millionen und einer feinteiligen anionischen Komponente. Das Retentionsmittel kann kationisch, anionisch, amphoter oder nichtionisch geladen sein. Als polymeres, synthetisches Retentionsmittel kommt z.B. mindestens ein Polymer aus der Gruppe der nichtionischen Polyacrylamide, der nichtionischen Polymethacrylamide, der kationischen Polyacrylamide, der kationischen Polymethacrylamide, der anionischen Polyacrylamide, der anionischen Polymethacrylamide, der Poly(N-vinylformamide), der Vinylamineinheiten enthaltenden Polymeren und der Polydiallyldimethylammoniumchloride in Betracht. Die mittlere Molmasse Mw der polymeren Retentionsmittel beträgt jeweils mindestens 2 Millionen Dalton, vorzugsweise mindestens 3 Millionen und liegt meistens in dem Bereich von beispielsweise 3,5 Millionen bis 15 Millionen. Die Ladungsdichte der in Betracht kommenden Polymeren beträgt beispielsweise höchstens 4,0 meq./g.The microparticle system according to the invention consists of at least one polymeric retention agent having a molecular weight M w of at least 2 million and a finely divided anionic component. The retention aid may be cationic, anionic, amphoteric or nonionic. At least one polymer from the group of nonionic polyacrylamides, the nonionic polymethacrylamides, the cationic polyacrylamides, the cationic polymethacrylamides, the anionic polyacrylamides, the anionic polymethacrylamides, the poly (N-vinylformamides), the polymers containing vinylamine units and, for example, at least one polymer, synthetic retention agent the Polydiallyldimethylammoniumchloride into consideration. The average molecular weight M w of the polymeric retention aids is at least 2 million daltons, preferably at least 3 million, and is usually in the range of, for example, 3.5 million to 15 million. The charge density of the polymers in question is for example at most 4.0 meq./g.

Besonders bevorzugt werden kationische Polyacrylamide mit einer mittleren Molmasse Mw von mindestens 5 Millionen Dalton und einer Ladungsdichte von 0,1 bis 3,5 meq./g und Polyvinylamine, die durch Hydrolyse von Vinylformamideinheiten enthaltenden Polymeren erhältlich sind und die eine mittlere Molmasse von mindestens 2 Millionen Dalton haben. Die Polyvinylamine werden bevorzugt durch Hydrolyse von Homopolymeren des N-Vinylformamids hergestellt, wobei der Hydrolysegrad beispielsweise bis zu 100%, meistens 70 bis 95% beträgt. Auch hochmolekulare Copolymerisate von N-Vinylformamid mit anderen ethylenisch ungesättigten Monomeren wie Vinylacetat, Vinylpropionat, Acrylsäuremethylester, Methacrylsäuremethylester, Acrylamid, Acrylnitril und/oder Methacrylnitril, können zu Vinylamineinheiten enthaltenden Polymeren hydrolysiert und erfindungsgemäß eingesetzt werden. Man kann beispielsweise sämtliche Polyvinylamine mit einer Molmasse Mw von mindestens 2 Millionen erfindungsgemäß verwenden, die durch Hydrolyse von Vinylformamideinheiten enthaltenden Polymeren erhältlich sind, wobei der Hydrolysegrad der Vinylformamideinheiten 0,5 bis 100 mol-% beträgt. Die Herstellung von Homo- und Copolymerisaten von N-Vinylformamid ist bekannt. Sie wird beispielsweise in der US 6,132,558 , Spalte 2 Zeile 36 bis Spalte 5, Zeile 25 ausführlich beschrieben. Die dort gemachten Ausführungen werden hiermit durch Bezugnahme zum Offenbarungsgehalt der vorliegenden Anmeldung gemacht.Particularly preferred are cationic polyacrylamides having an average molecular weight M w of at least 5 million daltons and a charge density of 0.1 to 3.5 meq./g and polyvinylamines obtainable by hydrolysis of vinylformamide units containing polymers and having an average molecular weight of at least Have 2 million daltons. The polyvinylamines are preferably prepared by hydrolysis of homopolymers of N-vinylformamide, wherein the degree of hydrolysis, for example, up to 100%, usually 70 to 95%. Also high molecular weight copolymers of N-vinylformamide with other ethylenically unsaturated monomers such as vinyl acetate, vinyl propionate, methyl acrylate, methyl methacrylate, acrylamide, acrylonitrile and / or methacrylonitrile, can be hydrolyzed to vinylamine units containing polymers and used according to the invention. For example, all polyvinylamines having a molecular weight M w of at least 2 million can be used according to the invention, which are obtainable by hydrolysis of vinylformamide units-containing polymers, the degree of hydrolysis of the vinylformamide units being 0.5 to 100 mol%. The preparation of homopolymers and copolymers of N-vinylformamide is known. For example, in the US 6,132,558 , Column 2, line 36 to column 5, line 25 described in detail. The statements made there are hereby incorporated by reference into the disclosure content of the present application.

Kationische Polyacrylamide sind beispielsweise Copolymerisate, die durch Copolymerisieren von Acrylamid und mindestens einem Di-C1-bisC2-alkylamino-C2-bisC4-alkyl(meth)acrylat oder einem basischen Acrylamid in Form der freien Basen, der Salze mit organischen oder anorganischen Säuren oder der mit Alkylhalogeniden quaternierten Verbindungen erhältlich sind. Beispiele für solche Verbindungen sind Dimethylaminoethylmethacrylat, Diethylaminoethylmethacrylat, Dimethylaminoethylacrylat, Diethylaminoethylacrylyat, Dimethylaminopropylmethacrylat, Dimethylaminopropylacrylat, Diethylaminopropylmethacrylat, Diethylaminopropylacrylat und/oder Dimethylaminoethylacrylamid, Dimethylaminoethylmethacrylamid, Dimethylaminopropylacrylamid, Dimethylaminopropylmethacrylamid und/oder Diallyldimethylammoniumchlorid. Die genannten Comonomeren können auch mit Methacrylamid zu kationischen Polymethacrylamiden copolymerisiert werden, die beispielsweise 5 bis 40 Mol-% mindestens eines kationischen Monomeren wie Dimethylaminoethylacrylat oder Diallyldimethylammoniumchlorid in einpolymerisierter Form enthalten. Kationische Polymethacrylamide können ebenfalls als polymeres Retentionsmittel des Mikropartikelsystems eingesetzt werden.Cationic polyacrylamides are, for example, copolymers prepared by copolymerizing acrylamide and at least one di-C 1 -bisC 2 -alkylamino-C 2 -bisC 4 -alkyl (meth) acrylate or a basic acrylamide in the form of the free bases, the salts with organic or inorganic acids or the alkyl halides quaternized compounds are available. 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 also be used as the polymeric retention aid of the microparticle system.

Weitere Beispiele für kationische Polyacrylamide und Vinylamineinheiten enthaltende Polymerisate können den zum Stand der Technik genannten Literaturstellen wie EP-A-0 910 701 und US-A-6,103,065 entnommen werden. Man kann sowohl lineare als auch verzweigte Polyacrylamide verwenden. Solche Polymere sind handelsübliche Produkte. Verzweigte Polymere, die z.B. durch Copolymerisation von Acrylamid oder Methacrylamid mit mindestens einem kationischen Monomer in Gegenwart geringer Mengen an Vernetzern herstellbar sind, werden beispielsweise in den zum Stand der Technik angegebenen Literaturstellen US-A-5,393,381 , WO-A-99/66130 und WO-A-99/63159 beschrieben.Further examples of polymers containing cationic polyacrylamides and vinylamine units may be the references cited in the prior art, such as EP-A-0 910 701 and US-A-6,103,065 be removed. One can use both linear and branched polyacrylamides. Such polymers are commercial products. Branched polymers which can be prepared, for example, by copolymerization of acrylamide or methacrylamide with at least one cationic monomer in the presence of small amounts of crosslinking agents are described, for example, in the references cited in the prior art US Patent No. 5,393,381 . WO-A-99/66130 and WO-A-99/63159 described.

Weitere geeignete polymere Retentionsmittel des Mikropartikelsystems sind Poly(N-vinylformamide). Sie werden beispielsweise durch Polymerisieren von N-Vinylformamid zu Homopolymerisaten oder durch Copolymerisieren von N-Vinylformamid zusammen mit mindestens einem anderen ethylenisch ungesättigtem Monomeren hergestellt. Die Vinylformamideinheiten dieser Polymeren werden - im Gegensatz zur Herstellung von Vinylamineinheiten enthaltenden Polymerisaten - nicht hydrolysiert Die Copolymerisate können kationisch, anionisch oder amphoter sein. Kationische Polymere erhält man beispielsweise durch Copolymerisieren von N-Vinylformamid mit mindestens einem der bei der Copolymerisation von Acrylamid genannten basischen Monomeren. Anionische Polymere von N-Vinylformamid sind durch Copolymerisieren von N-Vinylformamid in Gegenwart mindestens eines sauren monoethylenisch ungesättigten Monomeren erhältlich. Solche Comonomere sind beispielsweise monoethylenisch ungesättigte C3-bis C5-Carbonsäuren, Acrylamido-2-methylpropansulfonsäure, Styrolsulfonsäure oder Sulfopropylacrylat. Die sauren Monomeren können auch in vollständig mit Alkalimetall-, Erdalkalimetall- und/oder Ammoniumbasen neutralisierter Form bei der Copolymerisation mit N-Vinylformamid eingesetzt werden. Die genannten Copolymerisate enthalten Einheiten von anionischen oder kationischen Monomeren beispielsweise in Mengen von 0,5 bis 50, vorzugsweise 5 bis 40 Mol-% einpolymerisiert. Copolymerisate von N-Vinylformamid können außerdem amphoter sein, wenn sie Einheiten von anionischen und kationischen monoethylenisch ungesättigten Monomeren einpolymerisiert enthalten.Other suitable polymeric retention aids of the microparticle system are poly (N-vinylformamides). For example, they are prepared by polymerizing N-vinylformamide into homopolymers or by copolymerizing N-vinylformamide together with at least one other ethylenically unsaturated monomer. The vinylformamide units of these polymers are not hydrolysed, in contrast to the preparation of polymers containing vinylamine units. The copolymers can be cationic, anionic or amphoteric. Cationic polymers are obtained, for example, by copolymerizing N-vinylformamide with at least one of the basic monomers mentioned in the copolymerization of acrylamide. Anionic polymers of N-vinylformamide are obtainable by copolymerizing N-vinylformamide in the presence of at least one acid monoethylenically unsaturated monomer. Such comonomers are, for example, monoethylenically unsaturated C 3 -bis C 5 carboxylic acids, acrylamido-2-methylpropanesulfonic acid, styrenesulfonic acid or sulfopropyl acrylate. The acidic monomers can also be used in completely neutralized with alkali metal, alkaline earth metal and / or ammonium bases in the copolymerization with N-vinylformamide. The copolymers mentioned contain units of anionic or cationic monomers, for example, in amounts of 0.5 to 50, preferably 5 to 40 mol% copolymerized. Copolymers of N-vinylformamide can also be amphoteric if they contain units of anionic and cationic monoethylenically unsaturated monomers in copolymerized form.

Weitere geeignete Retentionsmittel sind nichtionische Polyacrylamide und nichtionische Polymethacrylamide, die durch Polymerisieren von Acrylamid und/oder Methacrylamid erhältlich sind, sowie anionische Polyacrylamide und anionische Polymethacrylamide. Die anionischen Poly(meth)acrylamide sind beispielsweise durch Polymerisieren von Acrylamid oder Methacrylamid mit mindestens einem anionischen Monomeren erhältlich. Als anionische Monomeren kommen beispielsweise monoethylenisch ungesättigte C3- bis C5-Carbonsäuren wie Acrylsäure, Methacrylsäure, Crotonsäure, Maleinsäure, Fumarsäure, Vinylessigsäure oder Ethacrylsäure, sowie Vinylphosphonsäure, Styrolsulfonsäure, Acrylamido-2-methylpropansulfonsäure, Sulfopropylacrylat oder Sulfopropylmethacrylat sowie die Alkalimetall-, Erdalkalimetall- und Ammoniumsalze der Säuregruppen aufweisenden Monomeren in Betracht. Die anionischen Copolymerisate enthalten beispielsweise 1 bis 50 Mol-%, vorzugsweise 5 bis 40 Mol-% mindestens eines anionischen Monomeren in einpolymerisierter Form. Außerdem können amphotere Copolymere von Acrylamid und Methacrylamid als polymeres Retentionsmittel des Mikropartikelsystems eingesetzt werden. Solche Copolymerisate sind erhältlich durch Copolymerisieren von Acrylamid oder Methyacrylamid in Gegenwart mindestens eines anionischen und mindestens eines kationischen ethylenisch ungesättigten Monomeren.Other suitable retention aids are nonionic polyacrylamides and nonionic polymethacrylamides obtainable by polymerizing acrylamide and / or methacrylamide, as well as anionic polyacrylamides and anionic polymethacrylamides. The anionic poly (meth) acrylamides are obtainable, for example, by polymerizing acrylamide or methacrylamide with at least one anionic monomer. Suitable anionic monomers are, for example, monoethylenically unsaturated C 3 -C 5 -carboxylic acids, such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, vinylacetic acid or ethacrylic acid, and vinylphosphonic acid, styrenesulfonic acid, acrylamido-2-methylpropanesulfonic acid, sulfopropyl acrylate or sulfopropyl methacrylate and the alkali metal, alkaline earth metal and ammonium salts of the acid group-containing monomers into consideration. The anionic copolymers contain, for example, 1 to 50 mol%, preferably 5 to 40 mol% of at least one anionic monomer in copolymerized form. In addition, amphoteric copolymers of acrylamide and methacrylamide can be used as the polymeric retention aid of the microparticle system. Such copolymers are obtainable by copolymerizing acrylamide or methacrylamide in the presence of at least one anionic and at least one cationic ethylenically unsaturated monomer.

Weitere geeignete kationische polymere Retentionsmittel des Mikropartikelsystems sind Polydiallyldimethylammoniumchloride (PolyDADMAC) mit einer mittleren Molmasse von mindestens 2 Millionen Dalton. Polymere dieser Art sind Handelsprodukte.Other suitable cationic polymeric retention aids of the microparticle system are polydiallyldimethylammonium chlorides (PolyDADMAC) with an average molecular weight of at least 2 million daltons. Polymers of this type are commercial products.

Die polymeren Retentionsmittel des Mikropartikelsystems werden dem Papierstoff in einer Menge von 0,005 bis 0,5 Gew.-%, vorzugsweise in einer Menge von 0,01 bis 0,25 Gew.-%, bezogen auf trockenen Papierstoff, zugesetzt.The polymeric retention aids of the microparticle system are added to the paper stock 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.

Als anorganische Komponente des Mikropartikelsystems kommen beispielsweise Bentonit, kolloidale Kieselsäure, Silikate und/oder Calciumcarbonat in Betracht. Unter kolloidaler Kieselsäure sollen Produkte verstanden werden, die auf Silikaten basieren, z.B. Silica-Microgel, Silical-Sol, Polysilikate, Aluminiumsilikate, Borsilikate, Polyborsilikate, Clay oder Zeolithe. Calciumcarbonat kann beispielsweise in Form von Kreide, gemahlenem Calciumcarbonat oder präzipitiertem Calciumcarbonat als anorganische Komponente des Mikropartikelsystems verwendet werden. Unter Bentonit werden allgemein Schichtsilikate verstanden, die in Wasser quellbar sind. Es handelt sich hierbei vor allem um das Tonmineral Montmorrillonit sowie ähnliche Tonmineralien wie Nontronit, Hectorit, Saponit, Sauconit, Beidellit, Allevardit, Illit, Halloysit, Attapulgit und Sepiolit. Diese Schichtsilikate werden vorzugsweise vor ihrer Anwendung aktiviert, d.h. in eine in Wasser quellbare Form überführt, in dem man die Schichtsilikate mit einer wäßrigen Base wie wäßrigen Lösungen von Natronlauge, Kalilauge, Soda, Pottasche, Ammoniak oder Aminen, behandelt. Vorzugsweise verwendet man als anorganische Komponente des Mikropartikelsystems Bentonit in der mit Natronlauge behandelten Form oder solche Bentonite, die bereits in der Natriumform gewonnen werden, sogenannte Wyoming Bentonite. Der Plättchendurchmesser des in Wasser dispergierten Bentonits beträgt in der mit Natromlauge behandelten Form beispielsweise maximal 1 bis 2 µm, die Dicke der Plättchen liegt bei etwa 1 nm. Je nach Typ und Aktivierung hat der Bentonit eine spezifische Oberfläche von 60 bis 800 m2/g. Typische Bentonite werden z.B. in der EP-B-0235893 beschrieben. Im Papierherstellungsprozess wird Bentonit zu der Cellulosesuspension typischerweise in Form einer wässrigen Bentonitslurry zugesetzt. Diese Bentonitslurry kann bis zu 10 Gew.-% Bentonit enthalten. Normalerweise enthalten die Slurries ca. 3 bis 5 Gew.-% Bentonit.Suitable inorganic components of the microparticle system are, for example, bentonite, colloidal silicic acid, silicates and / or calcium carbonate. Colloidal silicic acid is to be understood as meaning products based on silicates, for example silica microgel, silical sol, polysilicates, aluminum silicates, boron silicates, polyborosilicates, clay or zeolites. Calcium carbonate can be used, for example, in the form of chalk, ground calcium carbonate or precipitated calcium carbonate can be used 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 montmorillonite and similar clay minerals such as nontronite, hectorite, saponite, sauconite, beidellite, allevardite, illite, halloysite, attapulgite and sepiolite. These phyllosilicates 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 or those bentonites which are already obtained in the sodium form, so-called Wyoming bentonites, are preferably used as the inorganic component of the microparticle system. The platelet diameter of the water-dispersed bentonite in the sodium hydroxide-treated form is, for example, at most 1 to 2 μm, the thickness of the platelets is approximately 1 nm. Depending on the type and activation, the bentonite has a specific surface area of 60 to 800 m 2 / g , Typical bentonites are used in the EP-B-0235893 described. In the papermaking process, 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.

Als kollodiale Kieselsäure können Produkte aus der Gruppe von Siliciumbasierenden Partikel, Silica-Microgele, Silica-Sole, Aluminiumsilicate, Borosilikate, Polyborosilikate oder Zeolite eingesetzt werden. Diese haben eine spezifische Oberfläche von 50 bis 1500 m2/g und eine durchschnittliche Teilchengrößenverteilung von 1-250 nm, normalerweise im Bereich 5-100 nm. Die Herstellung solcher Komponenten wird z.B. in EP-A-0 041 056 , EP-A-0 185 068 und US-A-5,176,891 beschrieben.As 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 1500 m 2 / g and an average particle size distribution of 1-250 nm, normally in the range 5-100 nm. The preparation of such components is described, for example, in US Pat EP-A-0 041 056 . EP-A-0 185 068 and US-A-5,176,891 described.

Clay oder auch Kaolin ist ein wasserhaltiges Aluminiumsilikat mit plättchenförmiger Struktur. Die Kristalle haben eine Schichtstruktur und ein aspect ratio (Verhältnis Durchmesser zu Dicke) von bis zu 30 :1. Die Teilchengröße liegt z.B. bei mindestens 50 % kleiner 2 µm.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 μm.

Als Carbonate werden bevorzugt natürliches Calciumcarbonat (ground calcium carbonate, GCC) oder gefälltes Calciumcarbonat (precipitated calcium carbonate, PCC) eingesetzt. GCC wird beispielsweise durch Mahl- und Sichtprozesse unter Einsatz von Mahlhilfsmitteln hergestellt. Es besitzt eine Teilchengröße von 40 - 95 % kleiner 2 µm, die spezifische Oberfläche liegt im Bereich von 6-13 m2/g. PCC wird beispielsweise durch Einleiten von Kohlendioxid in eine wässrige Calciumhydroxidlösung hergestellt. Die durchschnittliche Teilchengröße liegt im Bereich von 0,03 - 0,6 µm. Die spezifische Oberfläche kann stark durch die Wahl der Fällungsbedingungen beeinflusst werden. Sie liegt im Bereich von 6 bis 13 m2/g.The carbonates used are preferably natural calcium carbonate (ground calcium carbonate, 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. For example, PCC is made by passing carbon dioxide into an aqueous calcium hydroxide solution. The average particle size is in the range of 0.03-0.6 μm. 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.

Die anorganische Komponente des Mikropartikelsystems wird dem Papierstoff in einer Menge von 0,01 bis 2,0 Gew.-%, vorzugsweise in einer Menge von 0,1 bis 1,0 Gew.-%, bezogen auf trockenen Papierstoff, zugesetzt.The inorganic component of the microparticle system is added to the 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 stock.

Bei dem erfindungsgemäßen Verfahren wird die wäßrige Faseraufschlämmung, die gegebenenfalls einen Füllstoff enthält, mindestens einer Scherstufe unterworfen. Sie durchläuft dabei mindestens eine Reinigungs-, Misch- und/oder Pumpstufe. Das Scheren der Pulpe (Dünnstoff) kann beispielsweise in einem Pulper, Sichter oder in einem Refiner erfolgen. Das Retentionsmittel wird gemäß Erfindung an mindestens zwei Stellen in den Dünnstoff und die feinteilige anorganische Komponente vor oder nach der Zugabe der Retentionsmittel oder zwischen zwei Dosierstellen für Retentionsmittel dosiert. Das Verfahren kann beispielsweise so durchgeführt werden, dass man das Retentionsmittel nach der letzten Scherstufe an mindestens zwei hintereinander liegenden Stellen zugibt und danach die feinteilige anorganische Komponente dosiert. In einer anderen Ausführungsform des erfindungsgemäßen Verfahrens gibt man das Retentionsmittel nach der letzten Scherstufe an mindestens zwei Stellen zu, die die gleiche Entfernung von der Scherstufe haben, und dosiert danach die feinteilige anorganische Komponente. Man kann das Verfahren jedoch auch so ausführen, dass man das Retentionsmittel vor der letzten Scherstufe an mindestens zwei Stellen zugibt, die in einer Ebene senkrecht zum Papierstoffstrom oder hintereinander angeordnet sind, und dass man die feinteilige anorganische Komponente nach der letzten Scherstufe dosiert. Außerdem kann man vor der letzten Scherstufe zunächst die feinteilige anorganische Komponente und danach mindestens ein Retentionsmittel oder eine Teilmenge des insgesamt einzusetzenden Retentionsmittels dosieren und nach der letzten Scherstufe das gleiche oder ein anderes Retentionsmittel oder das restliche Retentionsmittel zugeben. Man kann jedoch auch zunächst mindestens ein Retentionsmittel zum Dünnstoff dosieren, das System einer Scherung unterwerfen, dann mindestens ein Retentionsmittel (es kann mit dem zuerst dosierten Retentionsmittel identisch oder vorzugsweise verschieden sein) zufügen und danach mindestens eine feinteilige anorganische Komponente zugeben.In the process of the invention, the aqueous fiber slurry, optionally containing a filler, is subjected to at least one shear stage. It goes through at least one cleaning, mixing and / or pumping stage. The shearing of the pulp (thin material) can be done for example in a pulper, classifier or in a refiner. The retention agent is metered according to the invention in at least two places in the thin and the finely divided inorganic component before or after the addition of the retention agent or between two dosing sites for retention aid. The process can be carried out, for example, by adding the retention agent after the last shear stage to at least two successive points and then metering the finely divided inorganic component. In another embodiment of the method according to the invention, the retention agent after the last shear stage is added to at least two points which have the same distance from the shear stage, and then dosed the finely divided inorganic component. However, the process can also be carried out by adding the retention agent before the last shear stage at at least two points, which are arranged in a plane perpendicular to the stock flow or behind one another, and by metering the finely divided inorganic component after the last shear stage. In addition, before the last shear stage, it is possible first to meter the finely divided inorganic component and then at least one retention agent or a subset of the retention agent to be used in total, and to add the same or another retention agent or the remaining retention agent after the last shear stage. However, it is also possible first to dose at least one retention agent to the thin material, to subject the system to shear, then to add at least one retention agent (identical or preferably different to the first-dosed retention agent) and then to add at least one finely divided inorganic component.

Beispielsweise kann man bei dem erfindungsgemäßen Verfahren so vorgehen, dass man zunächst 25 bis 75 Gew.-% des gesamten Retentionsmittels vor der letzten Scherstufe, und den verbleibenden Anteil des Retentionsmittels danach dosiert und anschließend die feinteilige anorganische Komponente zugibt oder man dosiert zunächst vor der letzten Scherstufe die feinteilige anorganische Komponente und 25 bis 75 Gew.-% des Retentionsmittels und nach der letzten Scherstufe den verbleibenden Anteil des Retentionsmittels.For example, in the process according to the invention, it is possible first to meter 25 to 75% by weight of the total retention agent before the last shear stage and the remaining portion of the retention agent and then to add the finely divided inorganic component or to meter it first before the last Scherstufe the finely divided inorganic component and 25 to 75 wt .-% of the retention agent and after the last shear stage the remaining portion of the retention agent.

Bei einer anderen Ausführungsform des erfindungsgemäßen Verfahrens dosiert man jeweils vor der letzten Scherstufe zunächst die feinteilige anorganische Komponente und danach das Retentionsmittel an mindestens zwei in einer Ebene senkrecht zum Papierstoffstrom oder an hintereinander angeordneten Stellen. Die Fließgeschwindigkeit des Papierstoffstroms beträgt bei den meisten Papiermaschinen beispielsweise mindestens 2 m/sec und liegt meistens in dem Bereich von 3 bis 7 m/sec. Die Dosierung der Retentionsmittel kann beispielsweise mit Hilfe von Ein- oder Mehrstoffdüsen in den Papierstrom vorgenommen werden. Man erreicht damit eine rasche Verteilung der Retentionsmittel im Papierstoff.In another embodiment of the method according to the invention, the finely divided inorganic component is metered in each case before the last shearing stage, followed by the retention agent at least two in a plane perpendicular to the first Papierstoffstrom or at successively arranged locations. The flow rate of the paper pulp stream is, for example, at least 2 m / sec in most paper machines and is usually in the range of 3 to 7 m / sec. The dosage of the retention agent can be made for example by means of single or multi-fluid nozzles in the paper stream. This achieves a rapid distribution of the retention agent in the pulp.

Der Abstand zwischen dem Mittelpunkt der Dosierstellen der Retentionsmittel beträgt bei nacheinander erfolgender Zugabe von Retentionsmittel beispielsweise mindestens 20 cm. Der Abstand zwischen dem Mittelpunkt einer Dosierstelle für Retentionsmittel und dem Mittelpunkt einer Dosierstelle für die feinteilige anorganische Komponente beträgt beispielsweise ebenfalls mindestens 20 cm. Die Zugabestellen für Retentionsmittel können jedoch auch in einer Ebene senkrecht zum Papierstoffstrom angeordnet sein. Vorzugsweise beträgt der Abstand zwischen dem Mittelpunkt der Dosierstellen der Retentionsmittel mindestens 50 cm und der Abstand zwischen dem Mittelpunkt einer Dosierstelle für Retentionsmittel und dem Mittelpunkt einer Dosierstelle für die feinteilige anorganische Komponente mindestens 50 cm. Der Abstand zwischen dem Mittelpunkt der Dosierstellen der Retentionsmittel liegt in den meisten Fällen beispielsweise in dem Bereich von 50 cm bis 15 m, wobei der Abstand zwischen dem Mittelpunkt einer Dosierstelle für Retentionsmittel und dem Mittelpunkt einer Dosierstelle für die feinteilige anorganische Komponente z.B. mindestens 50 cm beträgt. Die Anordnung der Zugabestellen ist vorzugsweise derart, dass der Abstand zwischen dem Mittelpunkt der Dosierstellen der Retentionsmittel 50 cm bis 10 m und der Abstand zwischen dem Mittelpunkt einer Dosierstelle für Retentionsmittel und dem Mittelpunkt einer Dosierstelle für die feinteilige anorganische Komponente 50 cm bis 5 m beträgt.The distance between the center of the metering points of the retention agent is, for example, at least 20 cm in successive addition of retention agent. The distance between the center of a metering point for retention agent and the center of a metering point for the finely divided inorganic component, for example, also at least 20 cm. However, the retention sites for retention aids can also be arranged in a plane perpendicular to the stock flow. The distance between the center of the dosing points of the retention agent is preferably at least 50 cm and the distance between the center of a dosing point for retention agent and the center of a dosing point for the finely divided inorganic component at least 50 cm. The distance between the center of the dosing points of the retention agent is in most cases, for example in the range of 50 cm to 15 m, wherein the distance between the center of a dosing agent for retention agent and the center of a dosing point for the finely divided inorganic component, for. at least 50 cm. The location of the addition points is preferably such that the distance between the center of the dosing points of the retention agent is 50 cm to 10 m and the distance between the center of a dosing point for retention agent and the center of a dosing point for the finely divided inorganic component 50 cm to 5 m.

Wenn man beispielsweise zwei Dosierstellen für Retentionsmittel zur Verfügung hat, so kann man an beiden Dosierstellen das gleiche Retentionsmittel beispielsweise ein kationisches Polyacrylamid oder ein Polyvinylamin dosieren oder zwei unterschiedliche Retentionsmittel einsetzen z.B. ein kationisches Polyacrylamid und Diallyldimethylammoniumchlorid oder ein Polyvinylamin und ein Poly(N-vinylformamid) oder ein Polyvinylamin und ein kationisches Polyacrylamid. Die Retentionsmittel können auch an 3 bis 5 hintereinander angeordneten Stellen in den Papierstoffstrom dosiert werden. Ebenso ist es möglich, die feinteilige anorganische Komponente des Retentionsmittelsystems an mindestens zwei nacheinander angeordneten Stellen in den Papierstoffstrom zu dosieren.For example, if one has two dosing agents for retention aids, one can dose the same retention agent, for example, a cationic polyacrylamide or a polyvinylamine, or use two different retention agents, e.g. a cationic polyacrylamide and diallyldimethylammonium chloride or a polyvinylamine and a poly (N-vinylformamide) or a polyvinylamine and a cationic polyacrylamide. The retention agents can also be metered into the paper stock stream at 3 to 5 positions arranged one behind the other. Likewise, it is possible to meter the finely divided inorganic component of the retention agent system into the stock stream at at least two successive locations.

Außer dem Mikropartikelsystem kann man dem Papierstoff die üblicherweise bei der Papierherstellung verwendeten Prozeßchemikalien in den üblichen Mengen zusetzen, z.B. Fixiermittel, Trocken- und Naßfestmittel, Masseleimungsmittel, Biozide und/oder Farbstoffe. Der Papierstoff wird jeweils auf einem Sieb unter Blattbildung entwässert. Die so hergestellten Blätter werden getrocknet. Entwässern des Papierstoffs und Trocknen der Blätter gehören zum Papierherstellungsprozeß und werden in der Technik kontinuierlich durchgeführt.In addition to the microparticle system, it is possible to add to the paper stock the customary amounts of process chemicals customarily used in papermaking, for example fixatives, dry and wet strength agents, engine sizes, biocides and / or dyes. The paper stock is dewatered on a sieve with formation of sheets. The leaves thus produced are dried. Dehydrating the pulp and Drying of the sheets are part of the papermaking process and are carried out continuously in the art.

Nach dem erfindungsgemäßen Verfahren erhält man Papiere mit einer überraschend guten Formation und beobachtet gegenüber bekannten Mikropartikel-Verfahren eine verbesserte Füllstoff- und Feinstoffretention.The process according to the invention gives papers having a surprisingly good formation and, compared to known microparticle processes, has an improved filler and fines retention.

Die Prozentangaben in den Beispielen bedeuten Gewichtsprozent, sofern aus dem Zusammenhang nichts anderes hervorgeht.The percentages in the examples are by weight unless otherwise indicated in the context.

Die First Pass Retention (FPR) wurde durch Bestimmung des Verhältnisses des Feststoffgehaltes im Siebwasser zum Feststoffgehalt im Stoffauflauf ermittelt. Die Angabe erfolgt in Prozent.The First Pass Retention (FPR) was determined by determining the ratio of the solids content in the white water to the solids content in the headbox. The information is given in percent.

Die First Pass Ash Retention (FPAR) wurde analog zur FPR bestimmt, jedoch wurde nur der Ascheanteil berücksichtigt.The first pass ash retention (FPAR) was determined analogously to the FPR, but only the ash content was considered.

Die Formation wurde mit einem TECHPAP 2D Lab Formation Sensor von Firma Tecpap) gemessen. Der dimensionslose FX Wert ist in der Tabelle angegeben. Je niedriger dieser Wert ist, desto besser ist die Formation des getesteten Papiers.The formation was measured with a TECHPAP 2D Lab Formation Sensor from Tecpap). The dimensionless FX value is given in the table. The lower this value, the better the formation of the tested paper.

Für das Mikropartikelsystem wurden folgende Retentionsmittel verwendet:

Polymin® 215:
lineares, kationisches Acrylamidcopolymerisat einer mittleren Mol-masse Mw von 8 Millionen, einer Ladungsdichte von 1,7 meq/g und einem Feststoffgehalt von 46 %
Polymin® PR 8186:
verzweigtes, kationisches Acrylamidcopolymerisat mit einer mittleren Molmasse Mw von 7 Millionen, einer Ladungsdichte von 1,7 meq/g und einem Polymergehalt von 46%.
The following retention agents were used for the microparticle system:
Polymin® 215:
linear, cationic acrylamide copolymer having an average molecular weight M w of 8 million, a charge density of 1.7 meq / g and a solids content of 46%
Polymin® PR 8186:
branched, cationic acrylamide copolymer having an average molecular weight M w of 7 million, a charge density of 1.7 meq / g and a polymer content of 46%.

Als anorganische Komponente des Mikropartikelsystems wurde Mikroflocc® XFB eingesetzt. Mikrofloc® XFB ist ein Bentonitpulver, das durch Behandlung mit wässriger Natronlauge aktiviert wurde. Es wird üblicherweise vor Ort in eine 3 - 5%ige Suspension überführt.As an inorganic component of the microparticle system, Mikroflocc® XFB was used. Mikrofloc® XFB is a bentonite powder activated by treatment with aqueous caustic soda. It is usually converted on site in a 3-5% suspension.

BeispieleExamples

Die folgenden Beispiele und Vergleichsbeispiele wurden auf einer Versuchspapiermaschine mit GAP Former durchgeführt. Aus einem holzfreien, gebleichten Zellstoff wurde zunächst eine Pulpe mit einer Stoffdichte von 8 g/l und 20 % Calciumcarbonat als Füllstoff hergestellt, die in den Beispielen und in den Vergleichsbeispielen jeweils zu einem holzfreien Schreib- und Druckpapier mit einem Flächengewicht von 80 g/m2 verarbeitet wurde. Die Papiermaschine enthielt folgende Anordnung von Misch- und Scheraggregaten: Mischbütte, Verdünnung, Entlüfter, Screen (Sieb) und Stoffauflauf. Pro Stunde wurde jeweils eine Tonne Papier hergestellt. Die Zugabe (Menge und Dosierstelle) von Retentionsmittel und feinteiliger anorganischer Komponente wurde, wie in den Beispielen und Vergleichsbeispielen angegeben, variiert. Die dabei jeweils erhaltenen Ergebnisse sind in der Tabelle angegeben.The following examples and comparative examples were carried out on a GAP Former test paper machine. From a wood-free, bleached pulp was first prepared a pulp with a consistency of 8 g / l and 20% calcium carbonate as a filler, which in the examples and in the comparative examples in each case to a wood-free writing and printing paper having a basis weight of 80 g / m 2 was processed. The paper machine contained the following arrangement of mixing and shearing units: mixing vessel, dilution, deaerator, screen and headbox. One ton of paper was produced per hour. The addition (amount and metering point) of retention aid and finely divided inorganic component was varied as indicated in the examples and comparative examples. The results obtained in each case are given in the table.

Beispiel 1example 1

650 g/t Polymin 215 (die Angabe "650 g/t" bedeutet, dass pro Tonne hergestelltes Papier 650 g Polymin® 215 eingesetzt worden sind) wurden in 2 Dosiermengen zu 350 g/t und 300 g/t bei einem Abstand der Dosierstellen von 300 cm jeweils vor Screen und danach 2500 g/t Microfloc® XFB nach Screen dem oben beschriebenen Papierstoff zugeführt.650 g / t Polymin 215 (the term "650 g / t" means that 650 g Polymin® 215 were used per ton of produced paper) were added in 2 doses to 350 g / t and 300 g / t with a distance of the dosing of 300 cm in each case before screen and then 2500 g / t of Microfloc® XFB after screen fed to the paper stock described above.

Vergleichsbeispiel 1Comparative Example 1

Beispiel 1 wurde mit der einzigen Ausnahme wiederholt, dass man das Retentionsmittel (650 g/t Polymin 215) an einer einzigen Stelle zudosierte, die 400 cm vor Screen lag.Example 1 was repeated with the sole exception that the retention agent (650 g / t Polymin 215) was metered in at a single site 400 cm before screen.

Beispiel 2Example 2

450 g/t Polymin 215 wurden in 2 Dosiermengen zu 250 g/t und 200 g/t bei einem Abstand der Dosierstellen von 200 cm jeweils nach Screen und danach 2500 g/t Microfloc XFB ebenfalls nach Screen dem Papierstoff kontinuierlich zugegeben.450 g / t Polymin 215 were continuously added to the stock in 2 doses at 250 g / t and 200 g / t at a distance of the dosing of 200 cm after each screen and then 2500 g / t Microfloc XFB also after Screen.

Vergleichsbeispiel 2Comparative Example 2

Beispiel 2 wurde mit der einzigen Ausnahme wiederholt, dass man das Retentionsmittel (450 g/t Polymin 215) an einer einzigen Stelle zudosierte.Example 2 was repeated with the sole exception that the retention agent (450 g / t Polymin 215) was metered in at a single point.

Beispiel 3Example 3

Pro Tonne des hergestellten trockenen Papiers wurden dem Papierstoffstrom jeweils nach Screen 500 g Polyacrylamid in 2 Dosiermengen bei einem Abstand der Dosierstellen von 2 m kontinuierlich zugefügt, wobei man zuerst 250 g Polymin® 215, dann 250 g, Polymin® PR 8186 und danach 2500 g Microfloc® XFB (ebenfalls nach Screen) dosierte.Per ton of the dry paper produced, 500 g of polyacrylamide in 2 doses were continuously added to the paper stock stream at a distance of the metering points of 2 m, initially 250 g of Polymin® 215, then 250 g, Polymin® PR 8186 and then 2500 g Microfloc® XFB (also screened).

Beispiel 4Example 4

Pro Tonne des hergestellten trockenen Papiers wurden dem Papierstoffstrom jeweils kontinuierlich 500 g Polymin® 215 in 2 Dosiermengen zugefügt, wobei man zuerst 250 g Polymin® 215 vor Screen, dann 250 g Polymin® 215 nach Screen und danach 2500 g Microfloc XFB (ebenfalls nach Screen) dosierte. Der Abstand der 1. Dosierstelle für das Retentionsmittel lag 4m vor Screen, der Abstand der 2. Dosierstelle zum Screen betrug 2 m, der Abstand zwischen der Dosierstelle für Microfloc® XFB und dem Screen betrug 5 m. Tabelle FPR (%) FPAR (%) Formation/ Techpap Bsp. 1 79,1 54,2 97,6 Vgl. 1 78,0 52,1 122,3 Bsp. 2 81,5 58,3 81,7 Vgl. 2 80,7 56,4 99,6 Bsp. 3 81,0 58,1 75,3 Bsp. 4 82,1 59,7 98,3 Per ton of dry paper produced, 500 g of Polymin® 215 in 2 doses were added to the stock stream, first 250 g of Polymin® 215 before screen, then 250 g of Polymin® 215 on screen and then 2500 g of Microfloc XFB (also according to Screen ) dosed. The distance of the 1st metering point for the retention agent was 4 m in front of the screen, the distance of the second metering point to the screen was 2 m, the distance between the metering point for Microfloc® XFB and the screen was 5 m. table FPR (%) FPAR (%) Formation / Tech Pap Example 1 79.1 54.2 97.6 See 1 78.0 52.1 122.3 Ex. 2 81.5 58.3 81.7 See 2 80.7 56.4 99.6 Example 3 81.0 58.1 75.3 Example 4 82.1 59.7 98.3

Claims (19)

  1. A process for producing paper, board or cardboard by adding a microparticle system consisting of at least one cationic polymeric retention aid having a molar mass Mw of at least 2 million and a finely divided inorganic component to a paper stock having a density of not more than 20 g/l and draining the paper stock, the paper stock being subjected, before or after the addition of the cationic polymeric retention aid, to at least one shear stage, which comprises metering the cationic polymeric retention aid into the paper stock at at least two places and metering the finely divided inorganic component before or after the addition of the retention aid, wherein said finely divided inorganic component of the microparticle system comprises at least one bentonite, colloidal silica, silicates, calcium carbonate or mixtures thereof.
  2. The process according to claim 1, wherein the retention aid is added after the last shear stage at at least two successive places and thereafter the finely divided inorganic component is metered.
  3. The process according to claim 1, wherein the retention aid is added after the last shear stage at at least two places which are at equal distance from the shear stage, and thereafter the finely divided inorganic component is metered.
  4. The process according to claim 1, wherein the retention aid is added before the last shear stage at at least two places which are disposed in a plane perpendicular to the paper stock flow or successively, and the finely divided inorganic component is metered after the last shear stage.
  5. The process according to claim 1, wherein 25% to 75% by weight of the total retention aid is metered before the last shear stage and the remaining fraction of the retention aid thereafter, and subsequently the finely divided inorganic component is added.
  6. The process according to claim 1, wherein before the last shear stage first the finely divided inorganic component and 25% to 75% by weight of the retention aid and after the last shear stage the remaining fraction of the retention aid are metered in.
  7. The process according to claim 1, wherein before the last shear stage in each case first the finely divided inorganic component and the retention aid are metered in at at least two places disposed in a plane perpendicular to the paper stock flow or at places disposed successively.
  8. The process according to any one of claims 1 to 7, wherein the distance between the center point of the retention aid metering places is at least 20 cm and wherein the distance between the center point of a metering place for retention aid and the center point of a metering place for the finely divided inorganic component is at least 20 cm.
  9. The process according to any one of claims 1 to 8, wherein the distance between the center point of the retention aid metering places is at least 50 cm and wherein the distance between the center point of a metering place for retention aid and the center point of a metering place for the finely divided inorganic component is at least 50 cm.
  10. The process according to any one of claims 1 to 9, wherein the distance between the center point of the retention aid metering places is 50 cm to 15 m and wherein the distance between the center point of a metering place for retention aid and the center point of a metering place for the finely divided inorganic component is at least 50 cm.
  11. The process according to any one of claims 1 to 10, wherein the distance between the center point of the retention aid metering places is 50 cm to 10 m and wherein the distance between the center point of a metering place for retention aid and the center point of a metering place for the finely divided inorganic component is 50 cm to 5 m.
  12. The process according to any one of claims 1 to 11, wherein said retention aid comprises at least one polymer from the group of nonionic polyacrylamides, cationic polyacrylamides, anionic polyacrylamides, poly(N-vinylformamides), polymers comprising vinylamine units, and diallyldimethylammonium chlorides.
  13. The process according to any one of claims 1 to 12, wherein said retention aid comprises at least one cationic polymer having a charge density of not more than 4 meq/g.
  14. The process according to any one of claims 1 to 13, wherein said retention aid comprises at least one polymer having a molar mass Mw of at least 3 million.
  15. The process according to any one of claims 1 to 14, wherein said retention aid comprises at least one polyvinylamine obtainable by hydrolyzing polymers comprising vinylformamide units, the degree of hydrolysis of the vinylformamide units being 5 to 100 mol%.
  16. The process according to any one of claims 1 to 15, wherein the retention aid is used in an amount of 0.005% to 0.5% by weight, based on dry paper stock.
  17. The process according to any one of claims 1 to 16, wherein the retention aid is used in an amount of 0.001% to 0.25% by weight, based on dry paper stock.
  18. The process according to any one of claims 1 to 17, wherein the finely divided inorganic component of the microparticle system is used in an amount of 0.01% to 2.0%, preferably 0.1% to 1.0% by weight, based on dry paper stock, and is metered into the paper stock flow at at least two places disposed consecutively.
  19. The process according to any one of claims 1 to 18, wherein the retention aid is metered into the pulp flow at 3 to 5 places disposed successively.
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US7998314B2 (en) 2011-08-16
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CA2589653C (en) 2014-10-07

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