WO2005035872A1

WO2005035872A1 - Method for producing paper, paperboard and cardboard

Info

Publication number: WO2005035872A1
Application number: PCT/EP2004/011023
Authority: WO
Inventors: Oliver Birkert; Rainer Blum; Volker Braig; Simon Champ; Dieter Distler; Reinhold J. Leyrer; Volker Schädler; Oliver Koch
Original assignee: Basf Aktiengesellschaft
Priority date: 2003-10-06
Filing date: 2004-10-02
Publication date: 2005-04-21
Also published as: EP1673506A1; US20070119560A1; CN1863967A; CA2540117A1; DE10346750A1; BRPI0414844A

Abstract

The invention relates to a method for producing paper, paperboard and card board by adding (i) at least one retention agent and (ii) organic, ionic and uncrosslinked microparticles which are water-insoluble and whose mean particle size is less than 500 nm and whose ionic polymerisable monomer content is less than 1 % by weight or organic, ionic and uncrosslinked microparticles which are water-insoluble and whose mean particle size is less than 500 nm and whose ionic polymerisable monomer maximum content is equal to 10 % in weight obtainable by monomer polymerisation in the presence of silicon, waterglass, bentonite and/or the mixture thereof into a pulp and by dehydration of said pulp on a sieve.

Description

Process for the production of paper, cardboard and cardboard

description

The invention relates to a process for the production of paper, cardboard and cardboard by adding uncrosslinked organic microparticles and at least one retention agent for the paper stock and dewatering the paper stock on a sieve.

Inorganic microparticles such as bentonite or colloidal silicon dioxide brine are used in the manufacture of paper together with cationic polymers to improve the retention and drainage of the paper stock, cf. EP-A-0 235 893, EP-A-0 335 575, EP-A-0 310 959, US-A-4388 150 and WO-A-94/05595. In these processes, a cationic polymer is metered in in an amount of more than 0.03% by weight, based on dry paper stock, the mixture is then subjected to the action of a shear field, the flakes initially formed being broken down into microfibres, then bentonite is added or silica and dewatered the pulp thus obtained without further action by shear forces. According to the process of DE-A-102 36252, a microparticle system consisting of a cationic polymer and a finely divided inorganic component is metered into the paper stock after the last shear stage before the headbox and then the paper stock is dewatered. Compared to the sole use of cationic polymers as retention aids, the multi-component systems comprising cationic polymers and inorganic microparticles give papers with an improved formation.

From EP-A-0 462 365 organic microparticles are known which can be uncrosslinked or crosslinked and which each contain at least 1% by weight, but mostly at least 5% by weight, of an ionic comonomer in copolymerized form. The particle size of the uncrosslinked, water-insoluble microparticles is below 60 nm, while for the crosslinked microparticles it is less than 750 nm. The organic microparticles are used in paper manufacture together with a high molecular weight ionic polymer as a retention agent. In addition to the organic microparticles, bentonite or finely divided silica can also be used in paper production. Both synthetic organic polymers and polysaccharides can be considered as high molecular weight polymers.

From EP-A-0 810 274 binders based on aqueous styrene-acrylate polymer dispersions with an average film-forming temperature below 10 ° C. are known. The polymers can optionally contain up to 1% by weight of a monomer containing acid groups in copolymerized form. The particle size of the dispersed polymer particles is preferably in the range from 100 to 300 nm. The binders are used, for example, for the production of coating compositions such as plastic dispersion plasters, tile adhesives, paints and, in particular, low-emission emulsion paints. From WO-A-02/101145, aqueous mixtures are known which contain anionic, crosslinked, polymeric particles with a particle size in the non-swollen state of less than 750 nm, in particular from 25 to 300 nm, and colloidal anionic silica particles. The blends are used in the manufacture of paper together with a cationic polymer as a drainage and retention aid. However, they can also be used as flocculants and for the treatment of wastewater and sludge.

Further microparticle systems which are used in papermaking as an additive to the paper stock are known from EP-A-0 497 030 and EP-A-0 0635 602. From US-A-6 083 997 the production of an anionic nanocomposite is known which is used as a retention and drainage agent in papermaking. As can be seen from this, water glass is mixed with an anionic polyelectrolyte based on polysulfonates, polyacrylates or polyphosphates and either mixed with silica or the silica is produced in situ.

The object of the present invention is to provide a further method for producing paper, cardboard and cardboard using a microparticle system.

The object is achieved according to the invention with a process for the production of paper, cardboard and cardboard by adding ionic, water-insoluble, uncrosslinked, organic microparticles and at least one retention agent to a paper material and dewatering the paper material on a sieve if the organic microparticles are water-insoluble , uncrosslinked, organic polymers with an average particle size of less than 500 nm and a copolymerized ionic monomer content of less than 1% by weight or water-insoluble, uncrosslinked, organic microparticles with an average particle size of less than 500 nm and a copolymerized content ionic monomers of at most 10 wt .-%, which can be obtained by polymerizing the monomers in the presence of silica, water glass, bentonite and or mixtures thereof.

The specified particle sizes are always the weight-average particle sizes d50. It was determined by dynamic light scattering on a 0.01% by weight dispersion at 23 ° C. using an Autosizer lic from Malvern Instuments, England. The average particle size of the water-insoluble, uncrosslinked, organic polymers is preferably 10 to 100 nm and the content of copolymerized ionic monomers is 0.1 to 0.95% by weight. Microparticles with average particle sizes of the water-insoluble, uncrosslinked, organic polymers of 10 to 80 nm and a content of polymerized ionized see monomers from 0.2 to 0.7 wt .-%. The average particle size of the microparticles is usually in the range from 15 to 50 nm.

The microparticles of water-insoluble, uncrosslinked, organic polymers contain either at least one anionic monomer or one cationic monomer in copolymerized form. Aqueous dispersions which contain anionic microparticles are known from EP-A-0 810 274 cited in the prior art, page 3, line 3 to page 15, line 59. Suitable water-insoluble, uncrosslinked, organic polymers which carry an ionic charge can be obtained, for example, by free-radical aqueous emulsion polymerization of a monomer mixture

(a) 30 to 55 parts by weight of at least one monomer whose homopolymer has a glass transition temperature T _g <20 ° C,

(b) 45 to 70 parts by weight of at least one monomer whose homopolymer has a glass transition temperature T _g > 50 ° C. and

(c) 0.01 to less than 1 part by weight of a monomer with ionic groups,

the sum of the parts by weight from (a) and (b) is always 100. The monomers with ionic groups can either give the polymer an anionic charge if, for example, monoethylenically unsaturated monomers with acid groups are used in the polymerization, or a cationic charge if the polymerization is carried out in the presence of monoethylenically unsaturated, basic monomers. The glass transition temperature T _{g means} the limit value of the glass transition temperature which, according to G. Kanig (cf. colloid journal & magazine for polymers, volume 190, page, equation 1), strives with increasing molecular weight. It is determined using the DSC method (Differential Scanning Calorimetry, 20K min, midpoint). The T _g values for the homopolymers of most monomers are known, cf. for example Ulimann ^'s Encyclopedia of Industrial Chemistry, Verlag Chemie Weinheim, 1992, Volume 5, Vol. A21, page 169.

The monomer (a) is selected, for example, from at least one C to C ₀ alkyl acrylate, C ₅ to C ₁₀ alkyl methacrylate, C ₅ to C ₁₀ cycloalkyl (meth) acrylate, d to do dialkyl maleate and / or C. to C ₁₀ dialkyl fumarate. Typical monomers (b) are selected, for example, from at least one vinylaromatic monomer and / or an α, β-unsaturated carboxylic acid nitrile or dinitrile.

D to C _n alkyl groups are to be understood as meaning linear or branched alkyl radicals having 1 to n carbon atoms, for example methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, n-hexyl, 2 -Ethylhexyl, n-octyl, isooctyl and n-decyl. C ₅ - to C ₁₀ - cycloalkyl groups represent, for example, cyclopentyl, cyclohexyl or cyclooctyl, which can optionally be substituted in each case by 1, 2 or 3 alkyl groups having 1 to 4 carbon atoms. The water-insoluble, uncrosslinked, organic polymer is preferably composed of

35 to 50 parts by weight of monomer units (a), 50 to 65 parts by weight of monomer units (b) and 0.01 to 0.95 parts by weight of monomer units (c),

the sum of the monomer units (a) and (b) is always 100.

In the event that these are anionic monomers, the monomer (c) is selected, for example, from α, β-unsaturated C ₃ to C ₆ carboxylic acids, α, β-unsaturated C ₄ to C ₈ dicarboxylic acids, their anhydrides, monoethylenically unsaturated alkylsulfonic acids, monoethylenically unsaturated phosphonic acids and / or monoethylenically unsaturated arylsulfonic acids. The monomer (c) can optionally be used in the polymerization in a form partially or completely neutralized with alkali metal, alkaline earth metal and / or ammonium bases. It is also possible to neutralize polymers which contain the monomers (c) in copolymerized form in the form of the free acid groups during or after the end of the polymerization. Suitable bases are, for example, sodium hydroxide solution, potassium hydroxide solution, sodium carbonate, potash, sodium hydrogen carbonate, ammonia and amines such as Trimethylamine, propylamine or butylamine, pyridine, piperidine, morpholine and alkanolamines such as monoethanolamine, diethanolamine and triethanolamine, calcium oxide, calcium hydroxide, magnesium oxide and magnesium hydroxide. Preferred monomers of group (c) are acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, maleic anhydride, itaconic acid, itaconic anhydride, vinylsulfonic acid, methallylsulfonic acid, vinylbenzenesulfonic acid, acrylamidoethanesulfonic acid, acrylamido-2-methylpropanesulfonic acid (2-sulfatethyl) (2-sulfatethyl) meth) acrylate. Particularly preferred monomers in this group are acrylic acid, methacrylic acid and acrylamido-2-methylpropanesulfonic acid, mixtures of these monomers and their alkali metal and ammonium salts, in particular their sodium salts.

If the monomer (c) stands for cationic monomers, this includes, for example, the following monomers: diallyldimethylammonium chloride, di-d-to C ₂ -alkylamino-C ₂ - to C ₄ -alkyl (meth) acrylates and di-d-bis C ₂ alkylamino C ₂ to C alkyl (meth) acrylamides. The dialkylaminoalkyl (meth) acrylates and dialkylaminoalkyl (meth) acrylamides mentioned are preferably used in the form of salts with mineral acids, organic acids or in quaternized form. The quaternizing agent used is, for example, methyl chloride, ethyl chloride or dimethyl sulfate. Examples of preferred cationic monomers are diallyldimethylammonium chloride and the following salts of sulfuric acid or hydrochloric acid or compounds quaternized with methyl chloride: dimethylaminoethyl methacrylate, dimethylami- noethyl acrylate, dimethylaminopropyl methacrylate, dimethylaminoethyl methacrylamide and dimethylaminopropyl (meth) acrylamide. The polymers can also contain vinylamine units in the form of salts with mineral acids or in quaternized form as cationic groups. Polymers with such groups can be obtained, for example, if the polymerization is carried out in the presence of vinylformamide as a comonomer and then the vinylformamide units present in the copolymer are hydrolyzed to vinylamine units with sulfuric acid.

The monomers of group (c) are present in less than 1 part by weight, based on 100 parts by weight of the sum of monomers (a) and (b), in the monomer mixture which is subjected to the polymerization. The monomer mixture preferably contains 0.01 to 0.95, in particular 0.2 to 0.7 parts by weight of at least one monomer (c), based on 100 parts by weight of the monomers (a) and (b).

In addition to the aforementioned polymers from components (a), (b) and (c), paper is also used to produce such microparticles from water-insoluble, uncrosslinked, organic polymers with an average particle size of less than 500 nm and a content of copolymerized ionic Monomers of up to 10% by weight, which can be obtained by polymerizing the monomers on which these polymers are based in the presence of silica, water glass, bentonite and / or mixtures thereof. In this type of microparticle, the content of monomers of group (c) is, for example, 0.1 to 10, preferably 1.5 to 7 and in particular 2 to 5% by weight.

Examples of monomers (a) are vinyl ethers of C - to C ₁₀ -alkanols, branched and unbranched C ₃ - to C ₁₀ -olefins, d- to Cio-alkyl acrylates, C ₅ - to C ₁₀ -alkyl methacrylates, C ₅ - to Cιo-Cycloa! kyl (meth) acrylates, d- to Cio-Dialkylmaleinate and / or d- to do-Dialkylfumarate. Particularly preferred monomers in this group are, for example, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, 2-ethylhexalacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, di-n-butyl maleinate and / or di n-butyl fumarate.

Examples of suitable monomers (b) are vinyl aromatic monomers such as styrene or α-methylstyrene and styrene or α-methylstyrene substituted with 1, 2 or 3 d to C ₄ alkyl groups, chlorine and / or methoxy groups. Preferred monomers of group (b) have a glass transition temperature above 80 ° C. Examples include styrene, α-methylstyrene, o- or p-vinyltoluene, acrylonitrile, methacrylonitrile, maleic acid dinitile, fumaric acid dinitrile or mixtures thereof.

The copolymers can optionally include other monoethylenically unsaturated monomers such as acrylamide, methacrylamide, N-vinylpyrrolidone and N-vinylcaprolactam. contain polymerized. The amounts are, for example, 0 to 10 parts by weight, based on 100 parts by weight of the monomers (a) and (b).

The monomers are polymerized by the known methods of emulsion polymerization in the presence of initiators which form free radicals under the polymerization conditions, such as peroxides, hydroperoxides, azo compounds or redox initiators, and in the presence of emulsifiers. More detailed explanations can be found in EP-A-0 810 274, pages 4 and 5 already mentioned. However, the polymerization of the monomers in question can also be carried out in the presence of silica, water glass, bentonite and / or mixtures thereof. Aqueous dispersions of ionic, water-insoluble, uncrosslinked, organic polymers with an average particle size below 500 nm are obtained. However, the polymerization can also be carried out by mixing water, the monomers, a hydrocarbon which is liquid at room temperature, such as hexane, Pentane, isooctane, toluene and / or xylene, and at least one surface-active agent produces an emulsion and the monomers are polymerized in the presence of free radical initiators.

Polymers that are preferred

(a) at least one monomer from the group of n-butyl acrylate, isobutyl acrylate, n-propyl acrylate, isopropyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate and methyl acrylate,

(b) at least one monomer from the group styrene, α-methylstyrene, acrylonitrile and methacrylonitrile and

(c) at least one monomer from the group consisting of acrylic acid, methacrylic acid, maleic acid and acrylamido-2-methyl-propanesulfonic acid

copolymerized in the abovementioned quantities. Copolymers which contain copolymerized n-butyl acrylate and styrene in a weight ratio of 1: 1 and 0.2 to 0.7% by weight of methacrylic acid or acrylic acid are particularly preferred.

The average molecular weight M _{w of} the polymers is, for example, 500,000 to 5 million, preferably 1 million to 3 million.

The ionic, water-insoluble, uncrosslinked, organic microparticles described above are added to the paper stock together with at least one retention agent in the production of paper. The organic microparticles support the action of the retention aid. The organic microparticles are used, for example, in amounts of 0.1 to 1% by weight, preferably in amounts of 0.2 to 0.6% by weight, based on dry paper stock. The amounts of retention aid are, for example, 0.01 to 0.09, preferably 0.02 to 0.04% by weight, based on dry paper stock. All customary polymers known for this purpose can be used as retention agents, for example polyacrylamides, cationic polyacrylamides such as copolymers of acrylamide and dimethylaminoethyl acrylate which is quaternized with methyl chloride, polyvinylamines, polydiallyldimethylammonium chlorides, anionic polyacrylamides such as copolymers of acrylamide and acrylic acid or copolymers from acrylamide and methacrylic acid, also polydialkylaminoalkyl (meth) acrylamides such as polydimethylaminoethyl acrylamide and polydimethylaminoethyl methacrylamide, which are used in protonated or quaternized form, and polyethylene oxides, which can optionally be cationically and / or anionically modified. Come further

Polyamidoamines grafted with ethyleneimine and crosslinked with dichlorohydrin ethers of polyethylene glycols are considered as retention agents. Other common retention aids are cationic starches. Such starches are produced, for example, by reacting starch with cationizing agents such as 3-chloro-2-hydroxypropyltrimethylammonium chloride. The degree of substitution of the kattonic starch is, for example, 0.01 to 1, preferably 0.02 to 0.5. One can also use amphoteric starches as retention aids, provided that they have a cationic excess charge. As is known, the retention aids have a high molecular weight and thus differ essentially from fixatives which are based on the same monomer base. The molecular weight M _w der

Retention agent is, for example, at least 500,000, preferably> 1 million and mostly> 2 million and in particular> 5 million.

All paper qualities can be produced by the process according to the invention, e.g. Cardboard, single / multi-layer cardboard box, single / multi-layer liner, corrugated material, papers for newspaper printing, so-called medium-fine writing and

Printing papers, gravure papers and lightweight coating base papers. To produce such papers, one can start from wood pulp, thermomechanical material (TMP), chemo-thermomechanical material (CTMP), pressure cut (PGW), wood pulp as well as sulphite and sulphate pulp. The pulps can be both short-fiber and long-fiber. The process according to the invention is preferably used to produce wood-free grades which give bright white paper products.

The papers can optionally contain up to 40% by weight, mostly 5 to 35% by weight, of fillers. Suitable fillers are e.g. Titanium dioxide, natural and precipitated chalk, talc, kaolin, satin white, calcium sulfate, barium sulfate, clay and / or aluminum oxide.

Papermaking can also take place in the presence of customary process chemicals. For example, at least one fixing agent, strengthening agent for paper and / or a mass sizing agent can also be added to the paper stock. Suitable fixing agents are, for example, polymers containing vinylamine units, polydi allyldimethylammonium chloride, polyethyleneimines, polyalkylene polyamines and / or dicyandiamide polymers. The molecular weight M _{w of} the fixing agent is, for example, up to 300,000 and is usually in the range from 50,000 to 1 million.

According to the invention, water-insoluble, uncrosslinked, organic polymers with an average particle size of less than 500 nm and a copolymerized ionic monomer content of less than 1% by weight together with at least one cationic, anionic, amphoteric or neutral synthetic organic polymer and or cationic starch dosed as a retention aid to the paper stock before the last shear stage before the headbox. In one embodiment of the process according to the invention, water-insoluble, uncrosslinked, organic polymers having an average particle size of less than 500 nm and a copolymerized ionic monomer content of less than 1% by weight are metered into the paper stock together with at least one retention agent and a finely divided inorganic component after the last shear step before the headbox. However, the procedure can also be such that the retention agent before the last shear stage before the headbox and water-insoluble, uncrosslinked, organic polymers with an average particle size of less than 500 nm and a copolymerized ionic monomer content of less than 1% by weight alone or dosed together with the finely divided inorganic component after the last shear step before the headbox.

In addition, combinations of a polymeric organic retention agent and such water-insoluble, uncrosslinked, organic microparticles with an average particle size of less than 500 nm and a content of copolymerized ionic monomers of at most 10% by weight can be used in the production of paper can be obtained by polymerizing the monomers in the presence of silica, water glass, bentonite and / or mixtures thereof.

In a further embodiment of the process according to the invention, water-insoluble, uncrosslinked, organic polymers with an average particle size of less than 500 nm and a copolymerized ionic monomer content of less than 1% by weight are used together with polymers of monoethylenically unsaturated carboxylic acids, for example homopolymers of acrylic acid or methacrylic acid, copolymers of acrylic acid and methacrylic acid, copolymers of acrylic acid and maleic acid and / or copolymers of methacrylic acid and maleic acid. These polymers may optionally contain other monomers such as acrylamide and / or methacrylamide in copolymerized form. The molecular weight M _{w of} this group of polymers is, for example, 2,000 to 200,000 and is preferably in the range from 5,000 to 110,000. These polymers bring about an increase in the charge of the microparticles or a pre-aggregation of the microparticles and thus an improved retention in papermaking. According to a further process variant, the water-insoluble, uncrosslinked, organic polymers with a copolymerized ionic monomer content of less than 1% by weight are used together with inorganic microparticles from the group bentonite, colloidal silica, phyllosilicates and / or f one-part calcium carbonate. The particle size of the inorganic substances mentioned is, for example, 1 nm to 100,000 nm, preferably 5 to 500 nm. This particle size information relates in each case to the inorganic substances dispersed in water. For example, 0.01 to 10, preferably 0.05 to 2 and in particular 0.1 to 1.2 parts by weight of at least one type of inorganic microparticle are used per part by weight of the organic microparticles. If organic microparticles with a group (c) monomer content of up to at most 10% by weight are produced by polymerizing the monomers in the presence of silica, water glass and / or bentonite, - based on the weight of the resulting microparticles - Appropriate amounts of inorganic microparticles used in the polymerization.

Bentonite, colloidal silica, silicates and / or calcium carbonate are examples of inorganic components of the microparticle system. Colloidal silica is to be understood as meaning products based on silicates, for example silica microgel, silica sol, polysilicates, aluminum silicates, borosilicates, polyborosilicates, clay or zeolites. Calcium carbonate can be used, for example, in the form of chalk, ground calcium carbonate or precipitated calcium carbonate as the inorganic component of the microparticle system. Bentonite is generally understood to mean layered silicates that are swellable in water. These are primarily the clay mineral montmorrillonite and similar clay minerals such as nontronite, hectorite, saponite, sauconite, beidellite, allevardite, illite, halloysite, attapulgite and sepiolite. These layered silicates are preferably activated before their use, ie converted into a form which is more swellable in water, by treating the layered silicates with an aqueous base, such as aqueous solutions of sodium hydroxide solution, potassium hydroxide solution, soda ash or potash. Bentonite in the form treated with sodium hydroxide solution is preferably used as the inorganic component of the microparticle system. The platelet diameter of the bentonite dispersed in water in the form treated with sodium hydroxide solution is, for example, 1 to 2 μ, 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 described, for example, in EP-B-0235893. In the papermaking process, bentonite is typically added to the cellulose suspension in the form of an aqueous bentonite slurry. This bentonite slurry can contain up to 10% by weight of bentonite. The slurries normally contain approx. 3 - 5% by weight bentonite. Products from the group of silicon-based particles, silica microgels, silica sols, aluminum silicates, borosilicates, polyborosilicates or zeolites can be used as colloidal silica. These have a specific surface area of 50-1000 m ² / g and an average particle size distribution of 1-250 nm, normally in the range 40-100 nm. The production of such components is described, for example, in EP-A-0041056, EP-A- 0185068 and US-A-5176891.

Clay or kaolin is a water-containing aluminum silicate with a platelet structure. The crystals have a layer structure and an aspect ratio (diameter to thickness ratio) of up to 30: 1. The particle size is at least 50% less than 2 mm.

Natural calcium carbonate (ground calcium carbonate, GCC) or precipitated calcium carbonate (precipitated calcium carbonate, PCC) can be used as the carbonate, preferably calcium carbonate. GCC is manufactured by grinding and classifying processes using grinding aids. It has a particle size of 40 - 95% less than 2 mm, the specific surface is in the range of 6 - 13 m ² / g. PCC is made by introducing carbon dioxide into calcium hydroxide solution. The average particle size is in the range of 0.03 - 0.6 mm, the specific surface can be strongly influenced by the choice of the precipitation conditions. It is in the range of 6 - 13 m ² / g.

The process according to the invention gives papers with particularly good strength. The retention of fillers is improved compared to known processes.

Unless the context indicates otherwise, the percentages in the examples always mean percentages by weight. The molecular weights of the polymers were determined by light scattering.

Examples

Test specifications:

- Sheet formation device: Rapid-Köthen laboratory sheet former with accessories; Test according to DIN 54 358 Part 1 "Production of laboratory sheets for physical tests" = Rapid-Köthen method ISO 5269/2 Ash retention: First Pass Ash Retention (FPAR) A dynamic drainage jar was set to 900 rpm and then filled with 500 ml of fabric suspension (8g / l). After 10 seconds of stirring, x% of a polyacrylamide solution was added, the mixture was stirred at 900 rpm for 20 seconds and then reduced to 400 rpm. Then x%, based on the substance, of the anionic flocculation component was added as a dilute dispersion and the mixture was stirred at 400 rpm for a further 15 seconds. The dead volume of 25 ml was removed and discarded. 100 ml were collected in a volumetric flask and aspirated through a weighed white band filter. The filters were dried in a drying cabinet at 120 ° C, weighed and ashed at 550 ° C. The filler content was calculated from the residue depending on the filler composition according to the following relationship (1 - (filler in the filtrate, filler in the sample)) x100

Dry tear length, wet tear length: Device: BXC-FR2.5TN.D09-002 from Zwick / Roell

- Structural strength device: BXZ2.5 / TS1 S-006 from Zwick-Roell, tests in accordance with DIN ISO 3 781

feedstocks

Cationic polymer A

Commercial cationic polyacrylamide with a molecular weight of 4 to 6 million and a solids content of 45% (Polymin® KE 2020 from BASF Aktiengesellschaft)

silica

Commercially available colloidal silica with an average particle size of 5 to 10 nm and a solids content of 10% by weight.

Bentonite Commercially available swellable clay of the type montmorrillonite with a solids content of 90% and 10% water (see US-A-4 306 781), available under the trademark Microfloc® XFB from BASF Aktiengesellschaft Fixing agent A

Commercial polyvinylamine with a molecular weight M _w of 250,000 and a solids content of 21%, available under the name Catiofast® VFH from BASF Aktiengesellschaft

Anionic polymer A

Copolymer of acrylic acid and maleic acid with a molecular weight M _w of 70,000 and a solids content of 45%, available under the name Sokalan® CP45 from BASF Aktiengesellschaft

Nanohybrids A

Mixture of polymer 1 and silica in a weight ratio of 1: 1

Solvitose® BPN Cold soluble starch with a solids content of 95%, available from Avebe.

Preparation of polymer 1 to 4

Polymer 1

560 g of water and 633 g of a 15% strength by weight aqueous solution of aryl sulfonate were placed in a polymerization vessel before the solution was heated to 85 ° C. and then 50 g of a 7% strength aqueous sodium persulfate solution were added.

Then the monomer mixture (feed 1) and the amount of initiator (feed 2) were metered simultaneously into the polymerization vessel over two separate feeds, starting within 180 minutes, while maintaining the temperature.

After the feeds had ended, the temperature of 85 ° C. was maintained for a further 30 minutes and the reaction mixture was then cooled to room temperature. A pH of 4 was set with 3% aqueous sodium hydroxide solution.

Intake !:

Inlet 2:

The solids content of the dispersion was about 33%. The copolymer contained 0.6% methacrylic acid in a polymerized form. The light transmission of a 0.01% solution was 99%. The weight-average particle size d50 was 61 nm. The pH of the dispersion was 4.0 and the glass transition temperature Tg of the polymer was 23 ° C.

Polymer 2

800 g of a 2.5% strength Zeofloc® solution (JM Huber Corporation) and 253 g of a 15% strength aqueous solution of arylsulfonate were placed in a polymerization vessel, the solution was heated to 85 ° C. and then 20 g of a 7% strength were added. aqueous sodium persulfate solution.

Then, via two separate feeds, the monomer emulsion (feed 1) and the initiator solution (feed 2) were added to the polymerization vessel at the same time, starting at 180 min, and maintaining the temperature.

After the feeds had ended, the temperature of 85 ° C. was maintained for a further 30 minutes, the reaction mixture was then cooled to room temperature and filtered through a filter with a mesh size of 45 μm. The pH was then adjusted to 4.0 by adding 3% aqueous sodium hydroxide solution.

Inlet 1:

The solids content of the dispersion was approximately 16%. The copolymer contained 0.95% of polymerized methacrylic acid. The weight-average particle size d50 was 76 nm. The pH of the dispersion was 4.0 and the glass transition temperature Tg of the polymer was 31 ^° C. Polymer 3

300 g of water, 507 g of a 15% aqueous solution of arylsulfonate, 12 g of methacrylic acid and 800 g of a 5% aqueous sodium water glass solution with pH 11.2 were placed in a polymerization vessel, the solution was heated to 85 ° C. and added 40 g of a 7% aqueous sodium persulfate solution.

Then, via two separate feeds, the monomer mixture (feed 1) and the initiator solution (feed 2) were added to the polymerization vessel at the same time, starting at 180 min and maintaining the temperature, within 210 min.

After the feeds had ended, the 85 ° C. was maintained for a further 30 min, the resulting dispersion was then cooled to room temperature and filtered through a filter with a mesh size of 400 μm. The pH was then adjusted to 6.7 by adding 3% aqueous sodium hydroxide solution.

Inlet 1:

Feed 2: 40 g sodium persulfate solution (7% ιg, aqueous)

The solids content of the dispersion was about 25%. The copolymer contained 3% copolymerized methacrylic acid. The weight-average particle size d50 was 68 nm. The pH of the dispersion was 6.7. The glass transition temperature Tg of the polymer was 21 ° C. The dispersion was divided. A portion of the dispersion was then added with a 3% strength aqueous sodium hydroxide solution until the pH was 10.5. An aqueous dispersion with a solids content of approximately 23.5% was obtained.

Polymer 4

The other part of the aqueous dispersion of polymer 3 with a pH of 6.7 was adjusted to a pH of 10.5 by adding 5% aqueous sodium water glass solution. The solids content of the dispersion thus obtainable was 19.7%. Examples 1 to 6 Comparative Examples 1 to 4

The effectiveness of the polymers described above as a retention agent was first assessed on a fabric model consisting of a 70/30 mixture of pine sulfate / birch sulfate with 70% Schopper Riegler 33 and 30% Schopper Riegler 70, 30% Hydrocarb OG (based on pulp) and 0.6% solvitose ® BPN (based on pulp) tested according to the test instructions given above. The pulp had a consistency of 8 g / l, the pH of the pulp was 6.7. The type and amount of the starting materials and the results are given in Tables 1 to 4.

Table 1

Quantity added, kg of merchandise / t of paper

Table 2

Table 3

Quantity added, kg of merchandise / t of paper Table 4

* Quantity added, kg merchandise / t paper

Example 7 and Comparative Example 5

A wood-free paper stock with a stock concentration of 8 g / l and a pH of 6.7 was used as the fabric model. 0.1% (commercial goods) of fixative A, based on dry paper stock, were mixed in, the pulp was then added, the amounts of cationic polymer A and microparticles given in Table 5 were added, the components were thoroughly mixed and the pulp was dewatered as above described. The results are shown in Table 5.

Example 8

Example 7 was repeated with the exception that the use of fixing agent A was dispensed with. The results are shown in Table 5.

Table 5:

Quantity added, kg of merchandise / t of paper without the addition of fixing agents

Example 9 and Comparative Example 6

A wood-free paper stock with a stock concentration of 8 g / l and a pH of 6.7 was used as the fabric model. 1% of anionic polymer A, based on the amount of microparticles used, was added, the pulp was mixed, then the amounts of cationic polymer A and microparticles given in Table 6 were added added that the components were thoroughly mixed and dewatered the pulp as described above. The results are shown in Table 6.

Example 10 and Comparative Example 7

Example 9 was repeated with the exception that the use of anionic polymer A was omitted. The results are shown in Table 6.

Table 6

without adding Sokalan CP 45

Testing the application properties

500 ml of the stock suspension described above (stock density 8 g / l) were placed in a stirring vessel equipped with a propeller stirrer and stirred at a speed of 900 revolutions per minute (rpm). After 10 seconds, as in the ash retention test, a polyacrylamide solution (retention aid) was added, stirred for 20 seconds at 900 rpm and then at 400 rpm. The products listed in Table 7 (bentonite or polymer 1) were then metered in in an amount of 2 kg of merchandise per ton of paper. The mixture was then placed in a Rapid-Köthen sheet former and sheets with a basis weight of 80 g / m ^{2 were} produced. The dry and wet tear lengths and the structural strength of the leaves were then determined using the methods described above. The results are shown in Table 7.

Table 7

Example 11

Example 1 was repeated with the exceptions that 0.4 kg of commercial goods of cationic polymer A were used per t of paper and 2 kg of polymer 1 per t of paper. Ash retention (FPAR) was 89%.

Comparative Example 8

Example 1 was repeated with the exception that 0.4 kg of commercial goods of the cationic polymer A per t of paper and 2 kg of an anionically emulsified styrene latex with a particle size of 30 nm and a solids content of 33% were used. Ash retention (FPAR) was 81%.

Claims

claims

1. A process for the production of paper, cardboard and cardboard by adding ionic, water-insoluble, uncross-linked, organic microparticles and at least one retention agent to a paper stock and dewatering the paper stock on a sieve, characterized in that water-insoluble, uncrosslinked organic microparticles , organic polymers with an average particle size of less than 500 nm and a copolymerized ionic monomer content of less than 1% by weight or water-insoluble, uncrosslinked, organic polymers with an average particle size of less than 500 nm and a copolymerized content ionic monomers of at most 10 wt .-%, which can be obtained by polymerizing the monomers in the presence of silica, water glass, bentonite and / or mixtures thereof.

2. The method according to claim 1, characterized in that the average particle size of the water-insoluble, uncrosslinked, organic polymers is 10 to 100 nm and the content of copolymerized ionic monomers is 0.1 to 0.95% by weight. i. A method according to claim 1 or 2, characterized in that the average particle size of the water-insoluble, uncrosslinked, organic polymers is 10 to 80 nm and the content of copolymerized ionic monomers is 0.2 to 0.7% by weight.

4. The method according to any one of claims 1 to 3, characterized in that the average particle size of the water-insoluble, uncrosslinked, organic polymers is 15 to 50 nm.

5. The method according to any one of claims 1 to 4, characterized in that the water-insoluble, uncrosslinked, organic polymers contain at least one anionic monomer in copolymerized form.

6. The method according to any one of claims 1 to 4, characterized in that the water-insoluble, uncrosslinked, organic polymers contain at least one cationic monomer in copolymerized form.

7. The method according to any one of claims 1 to 6, characterized in that water-insoluble, uncrosslinked, organic polymers are used, which are obtainable by radical aqueous emulsion polymerization of a monomer mixture (a) 30 to 55 parts by weight of at least one monomer whose homopolymer has a glass transition temperature T _g <20 ° C, (b) 45 to 70 parts by weight of at least one monomer whose homopolymer has a glass transition temperature T _g > 50 ° C and (c) 0 , 01 to less than 1 part by weight of a monomer with ionic groups, the sum of the parts by weight from (a) and (b) always being 100.

8. The method according to claim 7, characterized in that the monomer (a) is selected from at least one d to C ₀ alkyl acrylate, C ₅ to C ₁₀ alkyl methacrylate, C ₅ to C ₀ cycloalkyl (meth) acrylate , d- to C ₁₀ -dialkyl maleate and / or C to Cio-dialkyl fumarate and the monomer (b) is selected from at least one vinyl aromatic monomer and / or an α, β-unsaturated carboxylic acid nitrile or dinitrile.

9. The method according to claim 7 or 8, characterized in that the monomer (c) is selected from α, β-unsaturated C ₃ - to C ₆ -carboxylic acids, α, β-unsaturated C - to C ₈ -dicarboxylic acids, their anhydrides , monoethylenically unsaturated alkylsulfonic acids, monoethylenically unsaturated phosphonic acids and / or monoethylenically unsaturated arylsulfonic acids.

10. The method according to claim 9, characterized in that the monomer (c) is used in the polymerization in partially or completely neutralized form with alkali metal, alkaline earth metal and / or ammonium bases.

11. The method according to any one of claims 7 to 10, characterized in that the water-insoluble, uncrosslinked, organic polymer is composed of 35 to 50 parts by weight of monomer units (a), 50 to 65 parts by weight of monomer units (b) and 0.01 to 0.95 Parts by weight of monomer units (c), the sum of the monomer units (a) and (b) always being 100.

12. The method according to any one of claims 7 to 11, characterized in that the water-insoluble, uncrosslinked, organic polymers are obtainable by polymerizing the monomers in the presence of silica, water glass, bentonite and / or mixtures thereof.

13. The method according to any one of claims 1 to 12, characterized in that at least one fixing agent, solidifying agent for paper and / or a mass sizing agent is additionally added to the paper stock.

14. The method according to claim 13, characterized in that the fixing agent used is a polymer containing vinylamine units, polydiallyldimethylammonium chloride, polyethyleneimine, polyalkylene polyamine and / or dicyandiamide polymer. 5. The method according to any one of claims 1 to 14, characterized in that water-insoluble, uncrosslinked, organic polymers with an average particle size of less than 500 nm and a copolymerized ionic monomer content of less than 1 wt .-% together with at least one dosed cationic, anionic, amphoteric or neutral synthetic organic polymer and / or cationic starch as a retention agent to the paper stock before the last shear mare before the headbox.

16. The method according to any one of claims 1 to 14, characterized in that water-insoluble, uncrosslinked, organic polymers with an average particle size of less than 500 nm and a copolymerized ionic monomer content of less than 1 wt .-% together with at least one Retention agent and a finely divided inorganic component to the paper stock after the last shear stage before the headbox or that the retention agent before the last shear stage before the headbox and water-insoluble, uncrosslinked, organic polymers with an average particle size of less than 500 nm and a content of polymerized ionic monomers of less than 1 wt .-% dosed alone or together with the finely divided inorganic component after the last shear stage before the headbox.