WO2002090406A1

WO2002090406A1 - Partial esters of allyl polyalkylene glycol ethers and their use as emulsifiers and hydrophilic monomers in emulsion polymerisation

Info

Publication number: WO2002090406A1
Application number: PCT/EP2002/004439
Authority: WO
Inventors: Hendrik Ahrens; Uwe Falk; Martin Glos
Original assignee: Clariant Gmbh
Priority date: 2001-05-04
Filing date: 2002-04-23
Publication date: 2002-11-14
Also published as: DE10121707A1

Abstract

The invention relates to partial esters of alcohols of formula (1), containing two divalent or polyvalent inorganic or organic acids, which in addition to oxygen atoms also have at least one phosphor or sulphur atom, whereby R represents a methyl or ethyl group, n represents a number from 1 to 100 and m represents a number from 0 to 500.

Description

description

Partial esters of allyl polyalkylene glycol ethers and their use as emulsifiers and hydrophilic monomers in emulsion polymerization

The present invention relates to partial esters of allyl polyalkylene glycol ether with polyvalent acids, and their use as emulsifiers and hydrophilic monomers in emulsion polymerizations.

The emulsifiers used for the emulsion polymerization according to the prior art are mostly anionic and nonionic emulsifiers.

Common anionic emulsifiers are sodium, potassium and ammonium salts of fatty acids, sodium alkylbenzenesulfonates, sodium alkylsulfonates, sodium olefin sulfonates, sodium polynaphthalene sulfonates, sodium dialkyldiphenylether disulfonates, sodium, potassium and ammonium alkyl sulfates, sodium, potassium and ammonium alkyl sulfates, glycol ether sulfates, sodium, potassium and ammonium mono- and dialkyl sulfosuccinates and monoalkylpolyoxethyl sulfosuccinates, as well as alkyl polyethylene glycol ether phosphoric acid mono-, di- and triesters and their mixtures and alkylphenol polyethylene glycol ether phosphoric acid mono-, di- and triester and their mixtures, as well as their sodium, potassium and ammonium salts.

Alkylphenol polyethylene glycol ether, alkyl polyethylene glycol ether, fatty acid polyethylene glycol ether, ethylene / propylene glycol block polymers and sorbitan ester polyethylene glycol ether are usually used as nonionic emulsifiers.

Emulsion polymerizations are made using anionic and Nonionic emulsifiers are generally carried out using the total batch or in the feed process, in which only a small part of the monomers to be polymerized is placed in the polymerization vessel and the larger part (50 to 100% by weight) is added as the polymerization progresses. The anionic or nonionic emulsifiers are optionally used in the feed or in the reactor receiver during the emulsion polymerization, or are added subsequently to the polymer dispersion prepared for stabilization.

The emulsifiers used according to the prior art are bound to the surface of the polymer particles via physical forces.

The object of the present invention was therefore to find new emulsifiers for emulsion polymerization. These emulsifiers are said to copolymerize with the monomers used and thus to be chemically bound in the polymer particles.

It has now been found that stable and low-coagulum polymer dispersions can be prepared with partial esters of allyl polyalkylene glycol ethers as emulsifiers in the emulsion polymerization.

The invention therefore relates to partial esters of alcohols of the formula (1)

with di- or polyvalent inorganic or organic acids, which in addition

Oxygen atoms still have at least one phosphorus or sulfur atom, wherein

R is a methyl or ethyl radical, n is a number from 1 to 100, and m is a number from 0 to 500. In a preferred embodiment of the invention, the alcohols of the formula 1 are those alkoxylates whose alkoxy groups are arranged in blocks.

In a preferred embodiment, n is a number from 2 to 50, in particular 3 to 30.

In a preferred embodiment, m denotes a number from 2 to 100, in particular 3 to 50.

In a preferred embodiment, R represents a methyl group.

Examples of inorganic acids which are suitable for forming the partial esters according to the invention are sulfuric acid and phosphoric acid. If phosphoric acid is used, the partial esters according to the invention can be either monoesters or diesters of phosphoric acid.

In a preferred embodiment, the organic or inorganic acids used to esterify the alcohols according to formula 1 are divalent or trivalent.

In a preferred embodiment, the organic acids are di-, tri- or polyvalent carboxylic acids, i.e. Compounds which contain 2, 3 or more carboxyl groups and which additionally have at least one functional group containing sulfur or phosphorus. Sulfur-containing functional groups, especially sulfonate groups, are particularly preferred.

The particularly preferred sulfonic acids / sulfonates can be aliphatic or aromatic compounds. Preferred sulfonic acids / sulfonates contain 2 or 3 carboxyl groups and, including the carboxyl groups, 3 to 6 carbon atoms. A particularly preferred sulfonic acid is sulfosuccinic acid. Particularly preferred partial esters thus correspond to formulas (2) to (5)

wherein R, m and n have the meaning given above, and M stands for an alkali metal ion, an ammonium ion or for H ⁺ .

The partial esters according to the invention can be prepared by reacting the alcohols of the formula 1 with suitable acids. However, care must be taken to ensure that the acids do not have an oxidizing effect, since otherwise the allylic double bond can be oxidized. For this reason, the preparation of partial sulfate esters is preferably carried out with amidosulfonic acid instead of with sulfuric acid. Phosphoric acid can be used for the preparation of partial phosphoric acid esters. Organic acids are preferably reacted in the form of their anhydrides with the alcohols of the formula 1. Functional groups are preferably inserted after the partial transfer has been produced non-functionalized acid. For example, the sulfosuccinic acid esters of formula 5 can be prepared by preparing the corresponding maleic acid esters and the subsequent sulfonation, for example using pyrosulfites.

Another object of the invention is the use of the partial esters according to the invention as polymerizable emulsifiers in emulsion polymerization.

In this use, the partial esters according to the invention are polymerized with further monomers from which a polymer dispersion is to be prepared. Unsaturated monomers are suitable for the production of polymer dispersions. Preferred olefinically unsaturated monomers are, for example

- Vinyl monomers, such as carboxylic acid esters of vinyl alcohol, for example

Vinyl acetate, vinyl propionate, vinyl ether of isononanoic acid or isodecanoic acid,

Aryl-substituted olefins, such as styrene and stilbene, olefinically unsaturated carboxylic acid esters, such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, i-butyl acrylate, pentyl acrylate, hexyl acrylate,

2-ethylhexyl acrylate, hydroxyethyl acrylate and the corresponding methacrylic acid esters, olefinically unsaturated dicarboxylic acid esters, such as dimethyl maleate, diethyl maleate, dipropyl maleate, dibutyl maleate, dopentyl maleate, dihexyl maleate and di-2-ethylhexyl maleinate, methacrylic acids and methacrylic acids, methacrylic acid and malonic acid, malic acid, malic acid, malic acid and malic acid, malic acid, malic acid, malic acid, malic acid and malic acid, malic acid, malic acid, malic acid, malic acid, malic acid, malic acid, malic acid, malic acid, malic acid, malic acid and malic acid, methacrylic acids, unsaturated carboxylic acid, olefinic and unsaturated carboxylic acid, methacrylic acids, methacrylic acid, and unsaturated carboxylic acid their sodium, potassium and ammonium salts, olefinically unsaturated sulfonic acids and phosphonic acids and their alkali and ammonium salts such as acrylamidomethyl propane sulfonic acid and their

Alkali and ammonium, alkylammonium and hydroxyalkylammonium salts, allylsulfonic acid and its alkali and ammonium salts, acryloyloxethylphosphonic acid and their ammonium and alkali salts as well the corresponding methacrylic acid derivatives, olefinically unsaturated amines, ammonium salts, nitriles and amides, such as dimethylaminoethyl acrylate, acryloyloxethyltrimethylammonium halide, acrylonitrile, N-methylacrylamide, N-ethylacrylamide, N-propylacrylamide, N-methylolacrylamide and the corresponding methacrylic acid derivative and the corresponding methacrylic acid derivative

Vinyl methylacetamide.

In a preferred embodiment, the above-mentioned monomers are mixed with further comonomers, preferably olefins or halogenated olefins having 2 to 8 carbon atoms, e.g. Polymerized ethylene, propene, butenes, pentenes, 1, 3-butadiene, chloroprene, vinyl chloride, vinylidene chloride, vinylidene fluoride and tetrafluoroethylene.

The invention therefore furthermore relates to a process for the preparation of polymer dispersions by polymerizing the partial esters according to the invention with olefinically unsaturated monomers in the aqueous phase, and to the aqueous polymer dispersion which can be prepared in this way.

To prepare the polymer dispersions, the water-immiscible monomers are generally finely divided in the aqueous phase in the form of micelles with the aid of the partial esters according to the invention and the radical polymerization reaction is initiated by initiators such as ammonium, sodium and potassium peroxodisulfate.

Further auxiliaries and additives for use with the partial esters according to the invention can be protective colloids such as carboxymethyl cellulose, hydroxyethyl cellulose, methyl hydroxypropyl cellulose, and partially and fully hydrolyzed polyvinyl alcohol.

Peter A. Lovell and Mohamed S. El-Aasser, in "Emulsion Polymerization and Emulsion Polymers", published by John Wiley and Sons, 1997, provide an overview of common processes, surfactants and other auxiliaries for emulsion polymerization. The partial esters according to the invention are placed in the reaction vessel before the start of the polymerization reaction or added to the reaction vessel during the polymerization reaction.

In general, the partial esters according to the invention are used in amounts of 0.1 to 50, preferably 0.2 to 10, in particular 0.4 to 4% by weight, based on the weight of the non-water-soluble or slightly water-soluble olefinically unsaturated used for the preparation of the polymer dispersion Monomers used as emulsifiers.

The partial esters according to the invention can be used both alone and in combination with other already known anionic and nonionic emulsifiers of the prior art, as described at the beginning. The amount of the anionic and nonionic emulsifiers of the prior art is then preferably 0.001 to 5, in particular 0.01 to 1% and particularly preferably 0.02 to 0.4% by weight, based on the weight of the insoluble or slightly water-soluble olefinically unsaturated Monomers.

The polymer dispersions produced with the partial esters according to the invention show low coagulum formation during and after the polymerization and an improvement in the shear, temperature and storage stability, the freeze / thaw stability and the electrolyte stability compared to divalent and trivalent cations such as calcium, barium and aluminum. An improvement in the film properties of the polymer films produced from the polymer dispersions can also be observed. The produced with the partial esters according to the invention

Polymer dispersions form films with low water absorption, a low whitening on contact with water, a small contact wrap against water and good wet and dry rub fastness. Examples

Production of partial starters

example 1

19 g of amidosulfonic acid and 0.5 g of 50% hypophosphorous acid were added to 100 g of an allyl polyoxyalkylene glycol under nitrogen. The mixture was heated to 80 ° C. for 5 hours and to 100 ° C. for 1 hour with vigorous stirring. After the reaction was allowed to cool, 1.8 g of 20% NaOH were added. 118 g (98.8%) of the sulfuric acid monoester were obtained.

Example 2

475 g of an allyl polyoxyalkylene glycol were mixed with 60.7 g of amidosulfonic acid and 1.88 g of urea under nitrogen and stirred vigorously at 100 ° C. for 3 h. After the reaction was allowed to cool, 2.5 g of 20% NaOH were added. 529 g (98.7%) of the sulfuric acid monoester were obtained.

Example 3

72.8 g of amidosulfonic acid and 2.25 g of urea were added to 210 g of an allylpolyoxyalkylene glycol under nitrogen and the mixture was stirred vigorously at 120 ° C. for 8 h. After the reaction was allowed to cool, 3 g of 20% NaOH were added. 280 g (99%) of the sulfuric acid monoester were obtained.

Example 4 500 g of an allyl polyoxyalkylene glycol were added under nitrogen with 97 g

Amidosulfonic acid added. The mixture was heated to 80 ° C. for 3 hours and to 100 ° C. for 4 hours with vigorous stirring. After the reaction was allowed to cool, 8 g of 20% NaOH were added. 592 g (99.1%) of the sulfuric acid monoester were obtained.

Example 5

500 g of an allyl polyoxyalkylene glycol became 98 g under nitrogen

Maleic anhydride added dropwise at 70 ° C. The mixture was then made for 4 h heated to 90 ° C and to a mixture of 52 g of sodium pyrosulfite, 40 g of NaOH and 180 g of dist. Water and reacted for 5 h at 80 ° C. 560 g of sulfosuccinate solution with a content of 80% by weight were obtained.

Example 6

210 g of an allyl polyoxyalkylene glycol were added dropwise to 74 g of maleic anhydride at 70 ° C. under nitrogen. The mixture was then heated to 90 ° C. for 8 h, during which the water formed was distilled off. The product obtained became a mixture of 39 g of sodium pyrosulfite, 30 g

NaOH and 135 g dist. Water was added and heated to 80 ° C for 5 h. 480 g of sulfosuccinate solution with a content of 74% by weight were obtained.

Example 7 475 g of an allyl polyoxyalkylene glycol became 61 g under nitrogen

Maleic anhydride added dropwise at 70 ° C. The mixture was then heated to 90 ° C. for 4 h and to a mixture of 33 g sodium pyrosulfite, 25 g NaOH and 113 g dist. Water and reacted for 5 h at 80 ° C. 690 g of sulfosuccinate solution with a content of 85% by weight were obtained.

Example 8

475 g of an allyl polyoxyalkylene glycol were mixed with 70 g of polyphosphoric acid at 70 ° C. and stirred at 70 ° C. for 2 hours. After a further 3 h at 100 ° C., 24 g of water were added at 90 ° C. and the mixture was stirred for another 2 h. 560 g of product were obtained, which was a mixture of 85% by weight of phosphoric acid monoester and 4% by weight of phosphoric acid diester, the rest being water. The product did not contain a phosphoric triester.

Example 9

500 g of an allylpolyoxyalkylene glycol were mixed with 113 g of polyphosphoric acid at 70 ° C. and stirred at 70 ° C. for 2 hours. After a further 2 hours at 100 ° C., 30 g of water were added at 90 ° C. and the mixture was stirred for a further 2 hours. It 630 g of product were obtained, which was a mixture of 82% by weight of phosphoric acid monoester and 5% by weight of phosphoric acid diester, the rest water. The product did not contain a phosphoric triester.

Example 10

210 g of an allyl polyoxyalkylene glycol were mixed at 70 ° C with 85 g of polyphosphoric acid and stirred at 70 ° C for 3 h. After a further 4 hours at 100 ° C., 20 g of water were added at 90 ° C. and the mixture was stirred for a further 2 hours. 310 g of product were obtained, which was a mixture of 79% by weight of phosphoric acid monoester and 4% by weight of phosphoric acid diester, the rest being water. The product did not contain a phosphoric triester.

Example 11

525 g of an allyl polyoxyalkylene glycol were mixed with 14 g under nitrogen

Amidosulfonic acid and 0.45 g of urea are added and the mixture is stirred vigorously at 120 ° C. for 3 h. After the reaction was allowed to cool, 2 g of 20% NaOH were added. 536 g (99.4%) of the sulfuric acid monoester were obtained.

Example 12

475 g of an allyl polyoxyalkylene glycol (4PO, 10EO) were mixed with 33 g of P ₂ O ₅ under nitrogen and stirred intensively at 90 ° C. for 8 h. 508 g of product were obtained, which is a mixture of about 50 mol% of phosphoric acid monoester and about 50 mol% of phosphoric acid diester.

Table 1: Allyl polyoxyalkylene glycols used

Production of polymer dispersions

Example 13 Styrene / acrylate dispersion

There were 1700 g of a monomer emulsion consisting of 554 g deionized water, 7.3 g of Emulsogen EPA ^® 073 (Natriumalkylpolyethylenglykolethersulfat, Clariant GmbH), 22 g of Allylpolyalkylenglycolethersulfat.es invention according to Example 2, 6 g sodium hydrogen carbonate, 360 g of styrene, 500 g n -Butyl acrylate, 240 g methyl acrylate and 11 g methacrylic acid and an initiator solution consisting of 5.55 g ammonium peroxodisulfate and 142.5 ml deionized water.

340.9 g of demineralized water were placed in a 3 liter reaction vessel and 11.0 g of the allyl polyalkylene glycol ether sulfate according to the invention were added. Under a nitrogen atmosphere and stirring with an anchor stirrer, the emulsifier solution in the reaction vessel was heated to 80 ° C. 37 ml of initiator solution and 42.5 ml of the monomer emulsion were then added. The radical polyaddition reaction begins. The reaction mixture was cooled over the water bath and kept constant at 79-81 ° C. The remaining 1657.5 g of the monomer emulsion and 111 g of the initiator solution were added over a period of 3 hours. The reaction mixture was then kept at 80 ° C. for a further hour over the water bath and then opened Cooled to room temperature. The pH of the polymer dispersion prepared was adjusted to pH 7-8 with 12.5% ammonia solution.

The resulting polymer dispersion has a solids content of 52% and a coagulate of <0.010% over a 100 μm sieve and <0.015% over a 40 μm sieve.

Example 14 Styrene / acrylate dispersion

There were 1700 g of a monomer emulsion consisting of 554 g of fully demineralized water, 33 g of the allyl polyalkylene glycol ether sulfate according to the invention, 6 g of sodium hydrogen carbonate, 360 g of styrene, 500 g of n-butyl acrylate, 240 g of methyl acrylate and 11 g of methacrylic acid and an initiator solution consisting of 5.55 g of ammonium peroxodisulfate and 142.5 ml of completely deionized water.

340.9 g of demineralized water were placed in a 3 liter reaction vessel and 11.0 g of the allylpolyalkylene glycol ether sulfate according to the invention were added. Under a nitrogen atmosphere and stirring with an anchor stirrer, the emulsifier solution in the reaction vessel was heated to 80 ° C. 37 ml of initiator solution and 42.5 ml of the monomer emulsion were then added. The radical polyaddition reaction begins. The reaction mixture was cooled over the water bath and kept constant at 79-81 ° C. The remaining 1657.5 g of the monomer emulsion and 111 g of the initiator solution were added over a period of 3 hours. The reaction mixture was then kept at 80 ° C. for a further hour over the water bath and then cooled to room temperature. The pH of the polymer dispersion prepared was adjusted to pH 7-8 with 12.5% ammonia solution.

The resulting polymer dispersion had a solids content of 52% and a coagulum of <0.030% over a 100 μm sieve and of <0.030% over a 40 μm sieve. Example 15 Pure acrylic dispersion

1800 g of a monomer emulsion consisting of 397.2 g of fully demineralized water, 9.6 g of EPA 073 emulsogen (sodium alkylpolyethylene glycol ether sulfate), 27.0 g of the allylpolyalkylene glycol ether sulfate according to the invention according to Example 2, 2.2 g of dodecyl mercaptan, 150 g of methyl methacrylate, 350 g of 2 -Ethylhexyl acrylate, 850 g n-butyl acrylate and 14 g methacrylic acid and 57 g of an initiator solution consisting of 7.1 g ammonium peroxodisulfate and 49.9 g deionized water.

263 g of demineralized water were placed in a 3 liter reaction vessel and heated to 80.degree. C. under a nitrogen atmosphere in a water bath.

Then 17 g of the initiator solution were added and immediately with the continuous addition of the 1800 g monomer emulsion and the remaining 40 g

Initiator solution started. Both components were metered in with constant stirring using an anchor stirrer and under a nitrogen atmosphere within a period of

3 hours. The reaction mixture was then heated at 80 ° C. for a further hour and then cooled to room temperature. The pH of the polymer dispersion prepared was adjusted to pH with 12.5% ammonia solution

7 - 8 set.

The resulting polymer dispersion had a solids content of 65% and a coagulate of <0.004% over a 100 μm sieve and of <0.006% over a 40 μm sieve.

Example 16 Styrene / Acrylate Dispersion

There were 1700 g of a monomer emulsion consisting of 565 g deionized water, 7.3 g of Emulsogen EPA ^® 073 (Natriumalkylpolyethylenglykolethersulfat, Clariant GmbH), 11 g of an invention Allylpolyalkylenglycol- ether phosphoric acid ester according to Example 12, 6 g of sodium bicarbonate, 360 g of styrene, 500 g of n-butyl acrylate, 240 g of methyl acrylate and 11 g of methacrylic acid and an initiator solution consisting of 5.55 g of ammonium peroxodisulfate and 142.5 ml of completely deionized water.

347.5 g of fully demineralized water were placed in a 3 liter reaction vessel and 4.4 g of EPA 073 emulsogen were added. Under a nitrogen atmosphere and stirring with an anchor stirrer, the emulsifier solution in the reaction vessel was heated to 80 ° C. 37 ml of initiator solution and 42.5 ml of the monomer emulsion were then added. The radical polyaddition reaction begins. The reaction mixture was cooled over the water bath and kept constant at 79-81 ° C. The remaining 1657.5 g of the monomer emulsion and 111 g of the initiator solution were added over a period of 3 hours. The reaction mixture was then kept at 80 ° C. for a further hour over the water bath and then cooled to room temperature. The pH of the polymer dispersion prepared was adjusted to pH 7-8 with 12.5% ammonia solution.

The resulting polymer dispersion had a solids content of 51% and a coagulate of <0.20% over a 100 μm sieve and of <0.30% over a 40 μm sieve.

Example 17 Pure acrylic dispersion

1800 g of a monomer emulsion consisting of 332.6 g of fully demineralized water, 24.1 g of emulsogen EPA 073 (sodium alkyl polyethylene glycol ether sulfate), 77.1 g of a 35% strength solution of an allyl polyalkylene glycol ether sulfosuccinate according to Example 7, 2.2 g of dodecyl mercaptan, 150 g of methyl methacrylate, 350 g of 2-ethylhexyl acrylate, 850 g of n-butyl acrylate and 14 g of methacrylic acid and 57 g of an initiator solution consisting of 7.1 g of ammonium peroxodisulfate and 49.9 g of fully deionized water. 263 g of demineralized water were placed in a 3 liter reaction vessel and heated to 80.degree. C. under a nitrogen atmosphere in a water bath. Then 17 g of the initiator solution were added and the continuous addition of the 1800 g monomer emulsion and the remaining 40 g initiator solution was started immediately. Both components were metered in with constant stirring using an anchor stirrer and under a nitrogen atmosphere over a period of 3 hours. The reaction mixture was then heated at 80 ° C. for a further hour and then cooled to room temperature. The pH of the polymer dispersion prepared was adjusted to pH 7-8 with 12.5% ammonia solution.

The resulting polymer dispersion had a solids content of 65% and a coagulum of <0.10% over a 100 μm sieve and of <0.15% over a 40 μm sieve.

Claims

claims

Partial esters of alcohols of the formula (1)

with di- or polyvalent inorganic or organic acids, which in addition

Oxygen atoms still have at least one phosphorus or sulfur atom, wherein

R is a methyl or ethyl radical, n is a number from 1 to 100, and m is a number from 0 to 500.

2. Partial ester according to claim 1, wherein the alkoxy groups are arranged in blocks.

3. Partial ester according to claim 1 and / or 2, wherein R represents a methyl group.

4. partial ester according to one or more of claims 1 to 3, wherein the acid is a di- or triacid.

5. Partial ester according to one or more of claims 1 to 4, wherein the acid is selected from the group consisting of sulfuric acid, phosphoric acid and sulfonic acids / sulfonates of carboxylic acids having 2 or 3 carboxyl groups and 3 to 6 carbon atoms.

6. Use of a partial ester according to one or more of claims 1 to 5 as a polymerizable emulsifier in the emulsion polymerization of olefinically unsaturated monomers.

7. Use according to claim 6, wherein co-emulsifiers selected from the group consisting of

Sodium, potassium and ammonium salts of fatty acids

Sodium alkyl sulfonates, sodium olefin sulfonates,

sodium alkylbenzenesulfonates,

Natriumpolynaphthalensulfonate,

Natriumdialkyldiphenyletherdisulfonate,

Sodium, potassium and ammonium alkyl sulfates, - sodium, potassium and ammonium alkyl polyethylene glycol ether sulfates,

Sodium, potassium and ammonium alkylphenol polyethylene glycol ether sulfates

Sodium, potassium and ammonium mono- and dialkylsulfosuccinates and monoalkylpolyoxethylsulfosuccinates, as well

Alkyl polyethylene glycol ether phosphoric acid mono-, di- and triesters and their mixtures and alkylphenol polyethylene glycol ether phosphoric mono-, di and triesters and their mixtures, as well as their sodium, potassium and

ammonium salts

alkylphenol,

Alkyl polyethylene glycol ether, - fatty acid polyethylene glycol ether,

Ethylene / propylene glycol block polymers and

Sorbitan ester polyethylene glycol ethers are used in amounts of 0.001 to 5% by weight, based on the weight of the olefinically unsaturated monomers.

8. A process for the preparation of polymer dispersions by polymerizing a partial ester according to one or more of claims 1 to 5 with olefinically unsaturated compounds in the aqueous phase.

9. Aqueous polymer dispersion which can be prepared by the process according to claim 8.