JPH0351839B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a composition for increasing paper strength, which is made of a polymer latex and a water-soluble polymer and has good penetration of a size liquid into paper. Conventionally, for example, anionic, cationic or amphoteric acrylamide water-soluble polymers have been used alone or in combination with epichlorohydrin-modified polyamide polyamines, or cationic or amphoteric acrylamide water-soluble polymers and anionic acrylamide water-soluble polymers have been used. In combination with polymers, known internal paper strength enhancers are added internally to strengthen base paper for box making, etc. However, in particular, the internal paper strength of cationic or amphoteric acrylamide water-soluble polymers is When a reinforcing agent is used, the general strength such as burst strength and compressive strength of the base paper increases, but the tear strength decreases and the penetration of the glue into the base paper decreases in the adhesive process performed in the later process, resulting in a decrease in adhesive strength. It has the disadvantage of reducing processing speed. In order to solve the drawback of the permeability of size liquid into paperboard, in parallel with adding the above-mentioned known paper strength enhancers to the pulp slurry, surfactants classified as antifoaming agents were added to the above-mentioned various types. It is added to pulp slurry along with a paper strength enhancer. However, this surfactant is insufficiently effective in such applications. The present inventors have found that the general strength of box-making base paper is strengthened, as is the case with the use of the known paper strength enhancer, and furthermore, there is no decrease in tear strength, and the base paper is resistant to glue during adhesive processing. In order to find a paper strength enhancing composition that has excellent permeability, the present invention was achieved as a result of intensive research. That is, the present invention provides: (1) obtained by polymerizing acrylamide in the presence of a polymeric latex [A] having a glass transition temperature of 60° C. or lower and substantially free of long-chain succinic anhydride derivatives; A composition for improving paper quality which is a cationic acrylamide polymer [B], in which A:(B-A) is a solid content weight ratio of 5:95 to
45:55, and the molar ratio of (non-cationic polymerized units): (cationic polymerized units) in (B-A) is
an aqueous solution composition consisting of a raw material composition of 97:3 to 70:30; (2) fatty acid esters, polyethylene oxide adducts of higher alcohols, and polyethylene oxide of alkyl phenols as surfactants classified as antifoaming agents; adducts, ethylene oxide adducts of polypropylene glycol, and acetylene glycols at a rate of 0.5% based on the solid content of the aqueous composition in (1) above.
It relates to a composition for increasing paper strength that contains up to 6% by weight and has good penetration of lake liquid into paper. In the present invention, the internally added paper strength enhancing composition consisting of a polymer latex and a water-soluble polymer component is
For example, as disclosed in JP-A-57-106798 and JP-A-57-154497, acrylamide and other monomers are added in the presence of a polymeric latex substantially free of long-chain succinic anhydride derivatives. Refers to various aqueous compositions obtained by copolymerization, etc. According to Japanese Patent Application Laid-Open No. 57-154497, the glass transition temperature is
A composition for improving paper quality which is a cationic acrylamide-based polymer [B] obtained by polymerizing acrylamide in the presence of a polymeric latex [A] at 60° C. or lower, wherein A:(B -A) has a solid content weight ratio of 5:95 to 45:55, and in (B-A) (non-cationic polymer unit): (cationic polymer unit)
A composition for improving paper quality characterized by comprising a raw material composition having a molar ratio of 97:3 to 70:30. More specifically, for example, (a) the above composition in which the cationic acrylamide polymer is obtained by polymerizing acrylamide and a cationic vinyl monomer; (c) The above composition in which the ionic acrylamide polymer has its acrylamide unit modified with a cation after polymerization; There are the above-mentioned compositions in which the acrylamide units are cationically modified after the copolymerization, but the compositions are not necessarily limited to these as long as the above conditions are met. The reason why A:(B-A) is limited to 5:95 to 44:55 in solid content weight ratio in the present invention is as follows. That is, paper obtained using a composition in which the amount of polymer latex used is less than the limited range does not have the effect of preventing a decrease in tear strength. On the other hand, paper obtained using a composition in which the amount of polymer latex used is greater than the specified range is insufficient in improving general strengths such as tear strength and compressive strength. Note that this ratio is preferably 10:90 to 40:60. The molar ratio of (non-cationic polymer unit): (cationic polymer unit) in (B-A) is 97:3 to 70:30.
The reason for this limitation is as follows. That is, the amount of cationic polymerized units is a fixing functional group that is adsorbed and fixed to pulp fibers when the paper strength improving composition of the present invention is added to pulp slurry in the paper manufacturing process, and improves the general strength of paper. It has an effect. Therefore, if the amount of cationic polymerized units serving as fixing functional groups is less than the limited amount, the fixing power to pulp fibers will be small and the effect of improving the general strength of paper will be insufficient. On the other hand, if the number of cationic polymer units is greater than the limited amount, the fixing force to the pulp fibers will be large, but the cohesive force between the pulp fibers will increase and the formation (uniformity) of the paper will decrease. The general strength-improving effect of Note that this ratio is preferably 95:5.
~75:25. Tear strength of paper obtained even when a composition of the present invention prepared in the absence of polymeric latex [A] and a composition obtained by simply mixing [A] is added to pulp slurry. No effect on preventing the decrease in The reason for this difference is that when a monomer such as acrylamide is polymerized in the presence of a polymeric latex to obtain the composition of the present invention, a portion of the monomer is graft-polymerized to the particles of the latex. This is thought to be due to the fact that The glass transition temperature of the polymer latex used in the present invention must be 60°C or lower, preferably 40°C or lower. The reason why this glass transition temperature is limited to 60° C. or less is to prevent a decrease in tear strength of the paper strength enhancing composition of the present invention. That is, if the glass transition temperature is higher than 60°C, the effect of preventing a decrease in tear strength is insufficient. The lower limit of this temperature can be about -90°C, but temperatures below -10°C may cause problems in terms of how easily the paper gets stained, so it is better to avoid it. The glass transition temperature (Tg) of a copolymer is a temperature calculated by the following formula. 1/(Tg+273)=〓(Wi/(Tgi+273)) Wi: Weight fraction of each comonomer component in the copolymer Tgi: Glass transition of homopolymer of each comonomer Temperature °C Cationic vinyl monomers are monomers that can be copolymerized with acrylamide, such as dimethylaminoethyl methacrylate, trimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, triethylaminoethyl methacrylate, and dimethylaminopropyl methacrylate. , trimethylaminopropyl methacrylate, methacrylic acid esters having an amino group such as 2-hydroxy-3-methacryloxypropyltrimethyl, their sulfates or hydrochlorides, or their acrylic acid derivatives are representative. However, two or more types can also be used in combination. A method of copolymerizing acrylamide or acrylamide with a cationic vinyl monomer in the presence of a polymeric latex and then further cationically modifying the acrylamide is to add an amino compound to the acid amide group of acrylamide using formaldehyde. The typical method is the addition method, ie, the method using the Mannitz reaction, but other methods such as the Hofmann reaction may also be used. In the above composition, when polymerizing the acrylamide copolymer, in addition to acrylamide or a vinyl monomer having a cationic property with acrylamide, if necessary, within a range that does not impede the object of the present invention, , these may be copolymerized with other monomers that can be copolymerized in an aqueous solution system. Representative examples of such monomers include unsaturated nitriles such as acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, itaconic acid,
These include unsaturated carboxylic acids such as maleic acid, fumaric acid, and crotonic acid, lower alkyl esters and lower hydroxyalkyl esters of these acids, and vinyl esters such as styrene, methylstyrene, and vinyl acetate. Can be used. The polymer latex used in the present invention is styrene-based latex obtained by a known polymerization method.
Butadiene type (hereinafter referred to as SBR), methyl methacrylate-butadiene type (hereinafter referred to as MBR),
Methyl methacrylate-styrene-butadiene type (hereinafter referred to as MSBR), acrylonitrile-butadiene type (hereinafter referred to as NBR), chloroprene type (hereinafter referred to as CR), isoprene type (hereinafter referred to as IR), and polybutadiene (hereinafter referred to as PB) Synthetic rubber latex such as vinyl acetate emulsion, emulsion latex such as vinyl acetate-acrylic acid ester emulsion, vinyl chloride latex containing vinyl chloride and vinyl acetate, or ethylene as the main raw material, vinylidene chloride and (meth)acrylic Vinylidene chloride latex, (meth)acrylic acid latex, etc. are made from acid ester as the main raw material, but in addition to the above-mentioned main raw materials, these polymer latexes also contain additives to improve the physical properties of the obtained polymer latex. In many cases, monomers copolymerizable with these main raw materials are also used, and it goes without saying that such latexes can also be used as latexes for the polymer of the present invention. In addition, (meth)acrylic acid ester here is
It is an ester of acrylic acid or methacrylic acid and typically the following alcohols. That is, methyl alcohol, ethyl alcohol,
These include butyl alcohol, ethylene glycol, 2-ethylhexyl alcohol, etc., but it goes without saying that esters of other alcohols are also similar. Monomers that can be copolymerized with the main raw material of the polymer latex include the following, but these are only representative examples; other monomers can also be copolymerized with the main raw material. It goes without saying that all monomers can be used. Namely, acrylic acid, itaconic acid, maleic acid,
Ethylenically unsaturated carboxylic acids such as fumaric acid and crotonic acid, aromatic vinyl compounds such as conjugated diolefins, styrene and methylstyrene, such as butadiene, isoprene and chloroprene, the above (meth)acrylic acid esters, acrylonitrile and methacrylonitrile. Ethylene nitrile compounds such as acrylamide, methacrylamide, N-methylol or N-methoxymethylacrylamide, N-methylol or N-methoxymethylmethacrylamide, (meth)acrylic acid amide compounds such as N-butoxymethylacrylamide, vinyl acetate , vinyl chloride, and vinyldene chloride. A surfactant classified as an antifoaming agent in this application is a property that imparts properties that allow water-based pastes such as starch pastes and vinyl acetate adhesives to penetrate well into paper sheets containing the surfactant. However, it also refers to a surfactant that does not cause the pulp slurry to foam when added to the pulp slurry during the papermaking process. Examples of surfactants that can be used in the present application include those based on fatty acid esters such as lauric acid, palmitic acid, stearic acid and oleic acid, including fatty acid monoesters of sorbitan, fatty acid sesquivalent acids, etc. Fatty acid esters of sorbitan such as esters and fatty acid triesters,
Fatty acid esters of polyoxyethylene sorbitan such as fatty acid monoester, fatty acid triester, fatty acid tetraester, fatty acid heptane ester, fatty acid hexaester of oligooxyethylene sorbitan, polyoxypropylene mannitol such as fatty acid monoester and fatty acid diester of polyoxypropylene mannitol fatty acid ester,
Fatty acid esters of polyethylene glycol, fatty acid diesters of polyethylene glycol, propylene glycol, including fatty acid monoesters of glycerol, fatty acid monoesters of ethylene glycol, fatty acid monoesters of diethylene glycol, fatty acid monoesters of tetraethylene glycol, fatty acid esters of hexaethylene glycol, etc. These include fatty acid monoesters of polyoxyethylene oxypropylene, and fatty acid monoesters of polyoxyethylene oxypropylene. Furthermore, lauryl alcohol, myristyl alcohol, cetyl alcohol, oleyl alcohol,
Polyethylene oxide adducts of higher alcohols such as Matsukow alcohol, polyethylene oxide adducts of alkylphenols such as nonylphenol, octylphenol, and dodecylphenol, ethylene oxide adducts of polypropylene glycol, acetylene glycol, and the like can be used. However, as a general tendency, it is preferable to use nonionic materials alone or in combination of two or more. When a surfactant classified as an antifoaming agent is blended in the production of an internally added paper strength enhancing composition consisting of a polymer latex and a water-soluble polymer component,
After adding surfactant to polymer latex,
By polymerizing acrylamide and others,
The compounding order for obtaining the paper strength enhancing composition of the present application by forming a water-soluble polymer component, and the process after producing an internally added paper strength enhancing composition consisting of a polymer latex and a water-soluble polymer component. , and a surfactant may be added thereto to obtain the paper strength enhancing composition of the present application. In general, it is easier to obtain better effects with the former. Further, if the polymer latex is emulsion polymerized using the above-mentioned suitable surfactant, it may not be necessary to specifically add this. The appropriate amount of the surfactant is 0.5 to 6% by weight based on the weight of the solid content of the internally added paper strength enhancing composition comprising a polymer latex and a water-soluble polymer component. When a water-soluble polymer is formed by polymerization after blending a surfactant into a polymer latex, the solid content concentration is 5 to 5 in total including that of the latex.
25% by weight is good. Furthermore, when a surfactant is added to an internally added paper strength enhancing composition consisting of a polymer latex and a water-soluble polymer component after manufacturing, the total solid content concentration is preferably 5 to 25% by weight. In general, after blending and stirring uniformly, it is necessary to hold for 30 minutes or more with or without stirring. This seems to be the time required for the surfactant to be adsorbed to the particles of the polymer latex component contained in the paper strength enhancing composition used in the present invention. That is, it is thought that the retention time after blending the surfactant and the blending concentration at the time of blending are involved in the speed and adsorption rate at which the surfactant is adsorbed onto the polymeric latex component. In the composition of the present invention, the surfactant is adsorbed to the polymeric latex component, and the surfactant is well fixed to the pulp fibers, so that a composition for increasing paper strength can be obtained in which the penetration of the size liquid is good. It is inferred. EXAMPLES The present invention will be specifically explained below using examples, comparative examples, etc., but the present invention is not limited to the following examples. In the following, parts and percentages are based on weight unless otherwise specified. Example 1 In a reactor under nitrogen gas, 25% styrene, 10% methyl methacrylate, 58% butyl acrylate, 2% β-hydroxyethyl methacrylate, and 2% methacrylic acid.
%, a monomer mixture consisting of 3% acrylamide
200g, 6g of sodium dodecylbenzenesulfonate,
500 g of water, 0.6 g of tert-dodecyl mercaptan, and 1 g of potassium persulfate were charged and reacted at 60°C for 15 hours. Add a 5% aqueous solution of caustic soda to this.
Adjust the pH to 6.8 and concentrate by heating and reducing pressure to create a polymer latex with a solid content of 45% (glass transition temperature is -
1°C). 66.7g of this acrylic ester latex,
624.6 g of distilled water, 4.0 g of polyoxyethylene oxypropylene fatty acid ester surfactant (trade name Pronal 502 manufactured by Toho Chemical Co., Ltd.), 237.0 g of 40% aqueous acrylamide solution, and 13.1 g of diethylaminoethyl methacrylate were added to a cooling tube, a stirrer, and Pour into a flask equipped with a thermometer, and add 13 g of 20% hydrochloric acid while stirring. Next, the liquid in the flask is heated to 40°C. 6.5 g of a 10% ammonium persulfate aqueous solution and 3.9 g of 10% acidic sodium sulfite were added to this, and a copolymerization reaction was carried out for 2.0 hours. After that, adjust the temperature of the liquid in the flask to 45℃, and 37%
After adding 11.4 g of a formaldehyde aqueous solution (hereinafter referred to as 37% formalin) and 19.8 g of 40% dimethylamine and performing a Mannitz reaction for 1.0 hour,
The internal solution was cooled until the temperature reached 20° C. to obtain 1000 g of the composition of the present invention (hereinafter referred to as composition 1). This is a milky white viscous aqueous solution with a solid content of approximately 15
%, the Burckfield viscosity was 4100 centipoise at 25°C. Example 2 In Example 1, instead of using the polyoxyethylene oxypropylene fatty acid ester surfactant during polymerization, an acetylene glycol surfactant (trade name Surfynol 104H, manufactured by Nissin Chemical Industry Co., Ltd.) was used in the Mannitz reaction. 1000 g of the composition of the present invention (hereinafter referred to as composition 2) was obtained under exactly the same conditions and operations as in Example 1, except that the internal liquid was cooled until the temperature of the internal liquid reached 20°C. Ta. This is a milky white viscous aqueous solution with a solid content of approximately 15
%, the Burckfield viscosity was 4700 centipoise at 25°C. Comparative Example 1 In Example 1, a paper strength strengthening composition (hereinafter referred to as Approximately 1000 g of Comparative Composition 1) was obtained. This is a milky white viscous aqueous solution with a solid content of approximately 15
%, the Burckfield viscosity was 4500 centipoise at 25°C. Example 3 Same as Example 2 except that 7.0 g of sorbitan-based surfactant (trade name: Span 85, manufactured by Kao Atlas Co., Ltd.) was added instead of 4.0 g of acetylene glycol-based surfactant. A composition for increasing paper strength that allows good penetration of the size liquid of the present invention under exactly the same conditions and operations (hereinafter abbreviated as composition 3)
About 1000g of was obtained. This is a milky white viscous aqueous solution with a solid content of approximately 15
%, the Burckfield viscosity was 4700 centipoise at 25°C. Example 4 In Example 2, instead of using 4.0g of acetylene glycol surfactant, the same surfactant was used.
Approximately 1,000 g of the paper strength enhancing composition (hereinafter referred to as composition 4) having good penetration of the size liquid of the present invention was prepared under the same conditions and operations as in Example 2, except that 2.0 g was added.
I got g. This is a milky white viscous aqueous solution with a solid content of approximately 15
%, the Burckfield viscosity was 4700 centipoise at 25°C. Comparative Example 2 Exactly the same conditions as in Example 1, except that the acrylate latex and polyoxyethylene oxypropylene fatty acid ester surfactant were not used in Example 1, and 624.6 g of distilled water was further reduced to 491.2 g. 795.9 g of a known internally added paper strength enhancer (hereinafter abbreviated as Comparative Composition 2) containing no polymeric latex or surfactant was obtained. This is a transparent viscous aqueous solution with a solid content of approximately 15
%, the Burckfield viscosity was 4300 centipoise at 25°C. Each of the above compositions was allowed to stand for 24 hours or more after production and then used in the following application examples. Example 5 133.3 g of a vinylidene chloride latex with a solid content of 45% and a pH of 6.8, consisting of 60% vinyl chloride and 40% vinylidene chloride, 630.9 g of distilled water, and 207.8 g of a 40% aqueous acrylamide solution were mixed with a cooling tube, a stirrer, and a temperature. Pour into a metered flask and perform the following operation while stirring. First, heat the liquid in the flask to 44°C. Next, 4 g of a 10% ammonium persulfate aqueous solution and 2.4 g of a 10% acidic sodium sulfite aqueous solution were added to carry out a polymerization reaction for 2 hours. After that, adjust the temperature of the liquid in the flask to 45℃, and add 6.6g of 37% formalin.
Add 11g of 40% dimethylamine aqueous solution and
After carrying out the Mannitz reaction for several hours, 4 g of a polyoxyethylene oxypropylene fatty acid ester surfactant was added, and the liquid temperature in the flask was cooled to 20°C to form the composition of the present invention (hereinafter referred to as composition 5). Obtained 1000g. This is a milky white viscous aqueous solution with a solids content of approximately 15% and a Burckfield viscosity.
It was 5020 centipoise at 25°C. Comparative Example 3 Glass transition temperature used in Example 2 -1°C
Instead of the acrylic ester latex, we used an acrylic ester latex with a glass transition temperature of 69°C, solid content of 45%, and pH 6.8, consisting of 40% styrene, 42% methyl methacrylate, 3% acrylic acid, and 15% butyl acrylate. 100 g of a comparative composition (hereinafter referred to as Comparative Composition 3) was obtained under the same conditions and operations as in Example 2 except that latex was used. This was a milky white viscous aqueous solution with a solids content of approximately 15% and a Bruckfield viscosity of 4800 centipoise at 25°C. Comparative Example 4 66.7 g of an acrylic ester latex with the same composition and physical properties as the polymer latex used in Example 2, 620.4 g of distilled water, and 300 g of a 40% acrylamide aqueous solution were placed in a flask equipped with a cooling tube, a stirrer, and a thermometer. Add and stir while performing the following operations. First, heat the liquid in the flask to 42°C. Next, 4 g of a 10% aqueous solution of ammonium persulfate and 2.4 g of a 10% aqueous solution of sodium acid sulfite.
was added to carry out the polymerization reaction for 2 hours. Thereafter, 4 g of acetylene glycol surfactant was added, the liquid temperature in the flask was cooled to 20°C, and the pH was adjusted to 6 with a caustic soda aqueous solution to obtain 1000 g of a comparative composition (hereinafter referred to as comparative composition 4). Ta. This was a milky white viscous aqueous solution with a solids content of approximately 15% and a Bruckfield viscosity of 4250 centipoise at 25°C. Application Examples The usefulness of Compositions 1, 2, 3, 4 and 5 will be illustrated below by comparison with Comparative Compositions 1, 2, 3 and 4. Freeness (hereinafter referred to as CSF) as shown by the Canadian standard freeness tester specified in JIS P8121: 450ml/CSF of 20g of cardboard waste paper pulp bone dry
Dispersion is performed for 2 minutes in a disintegrator using 2 liters of water. Next, 30 ml of Composition 1 diluted solution adjusted to a solid content concentration of 1.0% was added, and after stirring for 1 minute, 15 ml of 10% aluminum sulfate aqueous solution was added, followed by stirring for 5 minutes to form a pulp slurry with Composition 1 added. Obtained. Next, paper sheets were immediately formed using 800 ml of the pulp slurry containing Composition 1 in a square sheet machine, and after press dehydration for 15 minutes under a pressure of 3.0 Kg/cm ² , paper sheets were formed in a drum dryer at 110° C. for 2 hours. Dry for 20 minutes, then season in a room with a constant temperature of 20°C and 65% humidity for 24 hours. The basis weight of the thus obtained composition 1-added paper was 150
g/ ^m2 . In addition, using 450 ml of Composition 1-added pulp slurry, paper with a basis weight of 80 g/m ² was obtained under the same conditions and operations as the method used to obtain Composition 1-added paper with a basis weight of 150 g/m 2 .
^m2 of Composition 1 added paper was also obtained. Hereinafter, in the above, instead of composition 1, composition 2, 3, 4 or 5, comparative composition 1, 2, 3 or 4
or the same amount of surfactant contained in 30 ml of a 1.0% solids concentrated diluted solution of Composition 1, i.e. 0.08 g.
Composition 1 except that Comparative composition 1 or 2 is used.
Under exactly the same conditions and operations as when using
Papers with added compositions of g/m ² and 150 g/m ² were obtained. At the same time, as a control experiment, composition-free papers with basis weights of 80 g/m ² and 150 g/m ² were obtained under exactly the same conditions and operations as those using composition 1, except that composition 1 was not added. Ta. For the various additive-free papers and non-additive papers obtained, the specific rupture degree and specific tear strength were determined using paper with a basis weight of 80 g/ ^m2 , and the compressive strength and permeability of size liquid were determined using paper with a basis weight of 150 g/ ^m2 , respectively. Physical properties were measured. In addition, the specific rupture degree is JIS P8112, and the compressive strength is JIS P8112.
P8126, specific tear strength was conducted according to JIS P8116,
For the permeability test of size liquid, instead of using distilled water specified in JIS P8140, 5% oxidized starch (trade name Ace B) was used.
(manufactured by Oji Cornstarch Co., Ltd.). The results of these tests are shown in Tables 1 and 2. The paper strength enhancing composition obtained by the present invention, which has good penetration of the size solution, maintains general strengths such as specific bursting strength and compressive strength, while maintaining the composition without surfactant added or without surfactant. It is clear that the penetration of the size liquid is better than when the additive composition and surfactant are simply added to the pulp.

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Claims (1)

[Scope of Claims] 1 (1) Obtained by polymerizing acrylamide in the presence of a polymeric latex [A] having a glass transition temperature of 60°C or lower and substantially free of long-chain succinic anhydride derivatives. , a paper quality improving composition which is a cationic acrylamide polymer [B], wherein A:(B-A) is 5:95 in terms of solid content weight ratio.
~45:55, and the molar ratio of (non-cationic polymerized units):(cationic polymerized units) in (B-A) is 97:3 to 70:30. (2) Surfactants classified as antifoaming agents include fatty acid esters, polyethylene oxide adducts of higher alcohols, polyethylene oxide adducts of alkylphenols, ethylene oxide adducts of polypropylene glycol, and acetylene glycol. 0.5 based on the solid content weight of the aqueous composition in (1) above.
A composition for increasing paper strength, which contains 6% by weight and has good penetration of a size liquid into paper. 2. The aqueous composition according to claim 1, wherein the cationic acrylamide polymer is obtained by polymerizing acrylamide and a cationic vinyl monomer. 3. The aqueous composition according to claim 1, wherein the cationic acrylamide-based polymer has its acrylamide units cationically modified after polymerization. 4. A patent claim in which the cationic acrylamide polymer is a copolymer of acrylamide and a cationic vinyl monomer, and the acrylamide unit is cationically modified after copolymerization. Aqueous composition according to scope 1.