WO2009135812A1

WO2009135812A1 - Method for preparing an aqueous polymer dispersion

Info

Publication number: WO2009135812A1
Application number: PCT/EP2009/055334
Authority: WO
Inventors: Roelof Balk; Rajan Venkatesh; Arno Tuchbreiter; Franca Tiarks
Original assignee: Basf Se
Priority date: 2008-05-08
Filing date: 2009-05-04
Publication date: 2009-11-12

Abstract

Method for preparing fine-particulate aqueous polymer dispersions with a narrow particle size distribution.

Description

Process for the preparation of an aqueous polymer dispersion

description

The present invention is a process for the preparation of an aqueous polymer dispersion by free-radically initiated aqueous emulsion polymerization of ethylenically unsaturated monomers in the presence of at least one dispersant and at least one free-radical initiator, which is characterized in that for the emulsion

> 0.1 and <10 wt .-% of at least one alkene having 4 to 40 carbon atoms

[Monomers A],

> 0.1 and <10 wt .-% of at least one ethylenically unsaturated monomer having a solubility> 200 g per 1000 g of deionized water at 20 ⁰ C and 1 atm (absolute) [monomers B], and

> 80 and <99.8 wt .-% having a solubility of <100 g per 1000 g of deionized water at 20 ⁰ C of at least one ethylenically unsaturated monomers and 1 atm (absolute) [monomers C]

are used and add the monomers A to C to 100 wt .-% (Gesamtmonome- renmenge), wherein in an aqueous polymerization initially only

> 50 wt .-% of the total amount of the at least one monomer A,> 0.1 and <10 wt .-% of the total amount of the at least one monomer B, and

> 0.1 and <10 wt .-% of the total amount of the at least one monomer C

are initially charged and polymerized by free-radical polymerization (polymerization stage 1)

and thereafter adding the residual amounts of the monomers A to C to the aqueous polymerization medium under polymerization conditions and polymerizing (polymerization step 2).

The present invention likewise provides the aqueous polymer dispersions with narrow particle size which can be obtained by the process according to the invention. size distribution and the polymer powders obtainable from these aqueous polymer dispersions and the use of the aqueous polymer dispersions and the polymer powders in various fields of application, in particular as a constituent in transparent formulations for wood coatings.

Aqueous polymer dispersions are well known. These are fluid systems which contain a disperse phase in aqueous dispersion medium consisting of a plurality of intertwined polymer chains, which are known as polymer pellets or polymer particles, in disperse distribution. The average diameter of the polymer particles is frequently in the range from 10 to 1000 nm, in particular in the range from 50 to 600 nm. Aqueous polymer dispersions are used as binders in a large number of industrial applications.

The implementation of free-radically initiated emulsion polymerizations of ethylenically unsaturated monomers in an aqueous medium has often been described above and is therefore sufficiently known to the person skilled in the art [cf. for this emulsion polymerization in Encyclopedia of Polymer Science and Engineering, Vol. 8, pages 659 et seq. (1987); D. C. Blackley, in High Polymer Latices, Vol. 1, pp. 35 et seq. (1966); H. Warson, The Applications of Synthetic Resin Emulsions, Chapter 5, pages 246 et seq. (1972); D. Diederich,

Chemistry in Our Time 24, pages 135 to 142 (1990); Emulsion Polymerization, Interscience Publishers, New York (1965); DE-A 40 03 422 and dispersions of synthetic high polymers, F. Hölscher, Springer-Verlag, Berlin (1969)]. The free-radically initiated aqueous emulsion polymerization reactions are usually carried out by dispersing the ethylenically unsaturated monomers dispersively in aqueous medium in the form of monomer droplets and polymerizing them by means of a free-radical polymerization initiator.

If the particle size of the polymer particles to be prepared by means of the free-radically initiated aqueous emulsion polymerization is to be specifically adjusted, a so-called polymer seed is usually used which has either been prepared separately beforehand with other monomers (polymer foreign seed) or which can be prepared by partial polymerization of the monomers to be polymerized. generated in situ ".

The preparation of an aqueous polymer dispersion using an in situ polymer seed is familiar to the person skilled in the art (see, for example, DE-A 19609509, US Pat. EP-A 690882, EP-A 710680, EP-A 1125949, EP-A 1294816, EP-A 1614732, WO-A 03/29300) and is generally such that, prior to the actual emulsion polymerization, a small portion of the emulsion for the polymerization initially charged monomer mixture is introduced in the aqueous polymerization medium and is radically polymerized in the presence of a large amount of emulsifier.

However, the use of an in situ polymer seed always proves disadvantageous in view of a narrow particle size distribution if the monomer mixture used for the emulsion polymerization also contains readily water-soluble monomers.

According to a European patent application filed with priority by the Applicant to the European Patent Office with the application filing 07109999.8 only a subset of ethylenically unsaturated monomers having a low water solubility in aqueous polymerization medium and polymerized in a first polymerization, while the total amount of readily water-soluble monomers and the remaining amount of Monomers having a low water solubility are then subsequently free-radically polymerized in a second polymerization stage.

It was therefore an object of the present invention to provide an alternative process for preparing an aqueous polymer dispersion having a narrow particle size distribution by free-radically initiated aqueous emulsion polymerization using readily water-soluble and sparingly water-soluble ethylenically unsaturated monomers. It was also an object to provide an aqueous polymer dispersion which can be used as a binder in aqueous color glazes, which is characterized in particular by a good depth of color and good color brilliance in the wet state, and moreover has the clarity desired by the person skilled in the art.

Surprisingly, the problem has been solved by the method defined above.

For the preparation of the aqueous polymer dispersion, clear water, preferably drinking water and particularly preferably deionized water is used, the total amount of which is such that it contains 30 to 90% by weight and advantageously 40 to 60% by weight, based in each case on the aqueous polymer dispersion, is. Essential is that in polymerization stage 1 at least a partial amount, preferably> 25 wt .-% and particularly advantageously> 35 wt .-% of the total amount of water as a component of the aqueous polymerization in the polymerization together with the monomers A to C is submitted. Any residual amount of water remaining may be fed to the polymerization medium batchwise in one or more portions or continuously with constant or varying flow rates, in particular as constituent of an aqueous monomer emulsion in polymerization stage 2.

Suitable monomers A are alkenes having from 4 to 40 carbon atoms, preferably alkenes containing from 5 to 20 carbon atoms, and particularly preferably alkenes having from 6 to 12 carbon atoms, which can be radically copolymerized and which, apart from carbon and hydrogen, are not further elements exhibit. These include, for example, the linear alkenes n-butene-1, n-butene-2, 2-methylpropene, 2-methyl-1-butene-1, 3-methylbutene-1, 3,3-dimethyl-2-isopropylbutene-1, 2 Methylbutene-2, 3-methylbutene-2, pentene-1, 2-methylpentene-1, 3-methylpentene-1, 4-methylpentene-1, pentene-2, 2-methylpentene-2, 3-methylpentene-2, 4-methylpentene-2, 2-ethylpentene-1, 3-ethylpentene-1, 4-ethylpentene-1, 2-ethylpentene-2, 3-ethylpentene-2, 4-ethylpentene-2, 2,4,4-trimethylpentene 1, 2,4,4-trimethylpentene-2, 3-ethyl-2-methylpentene-1, 3,4,4-trimethylpentene-2, 2-methyl-3-ethylpentene-2, hexene-1, 2-methylhexene 1, 3-methyl-hexene-1, 4-methylhexene-1, 5-methylhexene-1, hexene-2, 2-methylhexene-2, 3-methyl-hexene-2, 4-methylhexene-2, 5-methylhexene 2, hexene-3, 2-methylhexene-3, 3-methyl-hexene-3, 4-methylhexene-3, 5-methylhexene-3, 2,2-dimethylhexene-3, 2,3-dimethylhexene-2, 2, 5-dimethylhexene-3, 2,5-dimethylhexene-2, 3,4-dimethylhexene-1, 3,4-dimethylhexene-3, 5,5-dimethylhexene-2, 2,4-dimethylhexene-1, heptene 1, 2-methylhe pten-1, 3-methylheptene-1, 4-methylheptene-1, 5-methylheptene-1, 6-methylheptene-1, heptene-2, 2-methylheptene-2, 3-methylheptene-2, 4-methylheptene-2, 5-methylhepten-2, 6-methyl-heptene-2, heptene-3, 2-methylhepten-3, 3-methylhepten-3, 4-methylhepten-3, 5-methyl-hepten-3, 6-methylhepten-3, 6,6-dimethylheptene-1,3,3-dimethylheptene-1, 3,6-dimethyl-heptene-1, 2,6-dimethylheptene-2, 2,3-dimethylheptene-2, 3,5-dimethylheptene

2, 4,5-dimethylheptene-2, 4,6-dimethylheptene-2, 4-ethylheptene-3, 2,6-dimethylheptane

3, 4,6-dimethylheptene-3, 2,5-dimethylheptene-4, octene-1, 2-methyl-octene-1, 3-methyl-octene-1, 4-methyl-octene-1, 5-methyl-octene-1, 6 Methyloctene-1, 7-Methyloctene-1, octene-2, 2-Methyloctene-2, 3-Methyloctene-2, 4-Methyloctene-2, 5-Methyloctene-2, 6-Methyloctene-2, 7-Methyloctene-2, Octene-3, 2-methyl-octene-3, 3-methyl-octene-3, 4-methyl-octene-3, 5-Methyloctene-3,6-Methyloctene-3,7-Methyloctene-3, Octene-4,2-Methyloctene-4,3-Methyl-octene-4,4-Methyloctene-4,5-Methyloctene-4,6 Methyl octene-4,7-methyloctene-4,7,7-dimethyloctene-1,3,3-dimethyloctene-1, 4,7-dimethyloctene-1, 2,7-dimethyloctene-2, 2,3-dimethyloctene-2, 3,6-Dimethyloctene-2, 4,5-dimethyloctene-2, 4,6-dimethyloctene-2, 4,7-dimethyloctene-2, 4-ethyloctene-3, 2,7-dimethyloctene-3, 4,7- dimethyloctene-3,

2,5-Dimethyloctene-4, nonene-1, 2-methylnone-1, 3-methylnone-1, 4-methylnone-1, 5-methylnone-1, 6-methylnone-1, 7-methylnone-1, 8- Methylnone-1, nonene-2, 2-methylnone-2, 3-methylnone-2, 4-methylnone-2, 5-methylnone-2, 6-methylnone-2, 7-methylnone-2, 8-methylnone-2, Nonene-3, 2-methylnone-3, 3-methylnone-3, 4-methylnone-3, 5-methylnone-3, 6-methylnone-3, 7-methylnone

3, 8-Methylnone-3, Nonen-4, 2-Methylnonen-4, 3-Methylnonen-4, 4-Methylnonen-4, 5-Methylnonen-4, 6-Methylnonen-4, 7-Methylnonen-4, 8- Methylnone-4,4,8-dimethyl-nonene-1, 4,8-dimethylnone-4,2,8-dimethylnone-4-decene-1,2-methyldecene-1,3-methyldecene-1,4-methyldecene 1, 5-methyldecene-1, 6-methyldecene-1, 7-methyldecene-1, 8-methyldecene-1, 9-methyldecen-1-decene-2, 2-methyldecene-2, 3-methyldecene-2, 4-methyldecene -2, 5-methyldecene-2, 6-methyldecene-2, 7-methyldecene-2, 8-methyl-decene-2, 9-methyldecene-2, decene-3, 2-methyldecen-3, 3-methyldecene-3 , 4-methyl-decene-3, 5-methyldecene-3, 6-methyldecen-3, 7-methyldecene-3, 8-methyldecen-3, 9-methyldecene-3, decene-4, 2-methyldecen-4, 3 Methyldecene-4, 4-methyldecene-4, 5-methyldecene-4, 6-methyldecene-4, 7-methyldecene-4, 8-methyldecene-4, 9-methyldecene

4, decene-5, 2-methyldecene-5, 3-methyldecene-5, 4-methyldecene-5, 5-methyldecene-5, 6-methyldecene-5, 7-methyldecene-5, 8-methyldecene-5, 9- Methyldecene-5, 2,4-dimethyl-decene-1, 2,4-dimethyldecene-2, 4,8-dimethyldecene-1, undecene-1, 2-methylundecene-1, 3-methylundecene-1, 4-methylundecene 1, 5-methylundecene-1, 6-methylundecene-1, 7-methylundecene-1, 8-methylundecene-1, 9-methylundecene-1, 10-methylundecene-1, undecene-2, 2-methylundecene-2, 3 Methylundecene-2, 4-methylundecene-2, 5-methyl-undecene-2, 6-methylundecene-2, 7-methylundecene-2, 8-methylundecene-2, 9-methyl-undecene-2, 10-methylundecene-2, Undecene-3, 2-methylundecene-3, 3-methylundecene-3, 4-methylundecene-3, 5-methylundecene-3, 6-methylundecene-3, 7-methylundecene-3, 8-methylundecene-3, 9-methylundecene 3, 10-methylundecene-3, undecene-4, 2-methyl-undecene-4, 3-methylundecene-4, 4-methylundecene-4, 5-methylundecene-4, 6-methyl-undecene-4, 7-methylundecene 4,8-methylundecene-4,9-methylundecene-4,10-methyl-undecene-4, undecene-5,2-methylundecene-5,3-M ethylundecene-5, 4-methylundecene-5, 5-methylundecene-5, 6-methylundecene-5, 7-methylundecene-5, 8-methylundecene-5, 9-methylundecene-5, 10-methylundecene-5, dodecene-1, Dodecene-2, dodecene-3, dodecene-4, dodecene-5, dodecene-6, 4,8-dimethyldecene-1, 4-ethyldecene-1, 6-ethyldecene-1, 8-ethyldecene-1, 2,5,8-trimethylnone-1, tridecene-1, tridecene-2, tridecene-3, tridecene-4, tridecene-5, tridecene-6, 2-methyldodecene-1,1,1-methyldodecene -1, 2,5-dimethyl-undecene-2, 6,10-dimethylundecene-1, tetradecene-1, tetradecene-2, tetradecene-3, tetradecene-4, tetradecene-5, tetradecene-6, tetradecene-7, 2 Methyl tridecene-1, 2-ethyldodecene-1, 2,6, 10-trimethylundecene-1, 2,6-dimethyldodecene-2, 1-methyltridecene-1, 9-methyltridecene-1, 7-methyltridecene-1, 8-ethyldodecene-1, 6-ethyldodecene-1, 4-ethyldodecene-1, 6-butyldecene-1, pentadecene-1, pentadecene-2, pentadecene-3, pentadecene-4, pentadecene-5, pentadecene-6, pentadecene- 7, 2-methyltetradecene-1, 3,7,11-trimethyldodecene-1, 2,6,10-trimethyldodecene-1, hexadecene-1, hexadecene-2, hexadecene-3, hexadecene-4, hexadecene-5, hexadecene-1. 6, hexadecene-7, hexadecene-8, 2-methylpentadecen-1, 3,7,11-trimethyltridecene-1, 4,8,12-trimethyltridecene-1, 1-methyl-pentadecene-1, 13-methyl-pentadecene-1, 7 -Methylpentadecene-1, 9-methylpentadecen-1 , 12-ethyltetradecene-1, 8-ethyltetradecene-1, 4-ethyltetradecene-1, 8-butyldodecene-1, 6-butyldodecene-1 heptadecene-1, heptadecene-2, heptadecene-3, heptadecene-4, heptadecene-5, Heptadecene-6, heptadecene-7, heptadecene-8,

2-methylhexadecene-1, 4,8,12-trimethyltetradecen-1, octadecene-1, octadecene-2, octadecene-3, octadecene-4, octadecene-5, octadecene-6, octadecene-7, octadecene-8, Octadecene-9, 2-methylheptadecen-1, 13-methylheptadecen-1, 10-butyltetradecen-1, 6-butyltetradecen-1, 8-butyltetradecen-1, 10-ethylhexadecen-1, nonadecen-1, nonadecene 2, 1-methyloctadecene-1, 7,1 1, 15-trimethylhexadecene-1, eicosene-1, eicosene-2, 2,6,10,14-tetramethylhexadecene-2, 3,7,1 1, 15-tetramethylhexadecene- 2, 2,7,1 1, 15-tetramethylhexadecene-1, docosen-1, docosen-2, docosen-7, 4,9,13,17-tetramethyl-octadecene-1, tetracoses-1, tetracoses-2, tetracoses -9, hexacosen-1, hexacosenes-2, hexacosen-9, triacont-1, dotriaconten-1 or tritriaconten-1 and the cyclic alkenes cyclopentene, 2-methylcyclopentene-1, 3-methylcyclopentene-1, 4-methyl-cyclopentene- 1, 3-butylcyclopentene-1, vinylcyclopentane, cyclohexene, 2-methylcyclohexene-1, 3-methylcyclohexene-1, 4-methylcyclohexene-1, 1, 4-dimethylcyclohexene-1, 3,3,5-trimethylcyclohexene-1, 4-cyclopentylcyclohexene-1, vinylcyclohexane, cyclohepthene, 1, 2-dimethylcycloheptene-1, cyclooctene, 2-methylcyclooctene-1, 3-methylcyclooctene-1, 4-methylcyclooctene 1, 5-methylcyclooctene-i, cyclonones, cyclodecene, cycloundecene, cyclododecene, bicyclo [2.2.1] heptene-2, 5-ethylbicyclo [2.2.1] heptene-2, 2-methylbicyclo [2.2.2] octene-2, Bicyclo [3.3.1] nonene-2 or bicyclo [3.2.2] nonene-6. Of course, mixtures of the aforementioned monomers A can be used.

The 1-alkenes are preferably used, for example 2-methylpropene, butene-1, pentene-1, hexene-1, heptene-1, octene-1, nonene-1, decene-1, undecene-1, dodecene-1, 2,4,4-trimethylpentene-1, 2,4-dimethylhexene-1, 6,6-dimethylheptene-1, 2-methyloctene-1, tridecene-1, tetradecene-1, hexadecene-1, heptadecene-1, octadecene-1 1, Nonadecen-1, Eicosen-1, Docosen-1, Tetracosen-1, 2,6-Dimethyldodecen-1, 6-Butyldecen-1, 4,8, 12-Trimethyldecen-1 or 2-Methylheptadecen-1. Advantageously, at least one monomer A is a 1-alken having 5 to 20 C atoms, preferably a 6 to 12

C-atoms having 1-alkene used. Particular preference is given to using octene-1, nonene-1, decene-1, undecene-1 and / or dodecene-1, with octene-1 and dodecene-1 being particularly preferred.

In the process according to the invention, the amount of monomers A is> 0.1 and <10% by weight, preferably> 0.1 and <5% by weight and particularly preferably> 0.5 and <3% by weight, in each case on the total monomer quantity.

As monomers B all those ethylenically unsaturated monomers tracht in loading which, preferably at 20 ⁰ C and 1 atm (1, 013 bar absolute) has a solubility> 200 G> 300 g and most preferably> 500 g per 1000 g of deionized water exhibit. Frequently, the monomers B have unlimited solubility in deionized water. Suitable monomers B are, in particular, those ethylenically unsaturated monomers which have at least one acid group, in particular a carboxylic acid or sulfonic acid group, a hydroxyalkyl group, an amide group, an ethyleneurea group, an acetoacetoxy group. With particular advantage, the monomers B are selected from the group consisting of acrylic acid, methacrylic acid, 2-acrylamido-2-methylpropanesulfonic acid (AMPS), vinylsulfonic acid, acrylamide, methacrylamide, N- (2-methacryloyloxyethyl) ethyleneurea (UMA), N- (2-) Acryloyloxyethyl) ethylene urea, 2-acetoacetoxyethyl acrylate, 2-acetoacetoxyethyl methacrylate (AAEM), diacetone acrylamide (DAAM), 2-hydroxyethyl acrylate, hydroxypropyl acrylate, 2-hydroxyethyl methacrylate and hydroxypropyl methacrylate. Particularly preferred are acrylic acid, methacrylic acid, acrylamide and / or AMPS. Of course, the monomers B also include the alkali metal or ammonium salts of the aforementioned monomers having an acid, in particular a carboxylic or sulfonic acid group.

In the process according to the invention, the amount of monomers B is> 0.1 and <10% by weight, preferably> 0.1 and <5% by weight and particularly preferably> 0.5 and <3% by weight, in each case on the total monomer quantity. As monomers C all those ethylenically unsaturated monomers come into consideration that at 20 ⁰ C and 1 atm (absolute) has a solubility of <100 g, preferably <60 g and especially preferably <20 g per 1000 g of deionized water having.

Particularly suitable monomers C are the ethylenically unsaturated compounds which can be readily copolymerized with the monomers A and B, such as, for example, vinylaromatic monomers, such as styrene, .alpha.-methylstyrene, o-chlorostyrene or vinyltoluene, vinyl halides, such as vinyl chloride or vinylidene chloride, esters Vinyl alcohol and 1 to 18 carbon atoms having monocarboxylic acids, such as vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl laurate and vinyl stearate, esters of preferably 3 to 6 carbon atoms having α, ß-monoethylenically unsaturated mono- and dicarboxylic acids, in particular acrylic acid , Methacrylic acid, maleic acid, fumaric acid and itaconic acid, with alkanols generally having 1 to 12, preferably 1 to 8 and in particular 1 to 4, carbon atoms, such as in particular methyl acrylate, methacrylic acid, ethyl, n-butyl , -iso-butyl, pentyl, -hexyl, -heptyl, -octyl, -nonyl, -decyl and -2-ethylhexylester, fumaric and maleic acid dimeth yl esters or di-n-butyl esters, nitriles of α, β-monoethylenically unsaturated carboxylic acids, such as acrylonitrile, methacrylonitrile, fumaronitrile, maleic acid dinitrile and C4-8-conjugated dienes, such as 1,3-butadiene (butadiene) and isoprene. The monomers mentioned generally form the main monomers which, based on the total amount of monomers C, account for> 80% by weight, preferably> 90% by weight and more preferably> 95% by weight, or even the total amount of monomers C form.

Monomers C, which usually increase the internal strength of the films of a polymer matrix, normally have at least one epoxy group or at least two non-conjugated ethylenically unsaturated double bonds. Examples include two vinyl radicals containing monomers, two vinylidene radicals having monomers and two alkenyl radicals having monomers. Particularly advantageous are the diesters of dihydric alcohols with α, ß-monoethylenically unsaturated monocarboxylic acids, among which acrylic and methacrylic acid are preferred. Examples of such two monomers having non-conjugated ethylenically unsaturated double bonds are alkylene glycol diacrylates and dimethacrylates, such as ethylene glycol diacrylate, 1,2-propylene glycol diacrylate, 1,3-propylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butylene glycol diacrylate and ethylene glycol dimethacrylate, 1, 2-propylene glycol dimethacrylate, 1, 3-propylene glycol dimethacrylate, 1, 3-butylene glycol dimethacrylate, 1, 4-butylene glycol dimethacrylate and divinylbenzene, vinyl methacrylate, vinyl acrylate, allyl methacrylate, allyl acrylate, diallyl maleate, diallyl fumarate, cyclopentadienyl acrylate, triallyl cyanurate or triallyl isocyanurate. Frequently, the aforementioned crosslinking monomers C in amounts of <10 to wt .-%, but preferably in amounts of <5 wt .-%, in each case based on the total amount of monomers C used. Frequently, however, no such crosslinking monomers C are used.

Advantageously used in the process according to the invention as monomers C are such monomer mixtures which

50 to 100 wt .-% esters of acrylic and / or methacrylic acid having 1 to 12 carbon atoms alkanols and / or styrene, or

From 50 to 100% by weight of styrene and butadiene, or

From 50 to 100% by weight of vinyl chloride and / or vinylidene chloride, or

40 to 100% by weight of vinyl acetate or vinyl propionate and ethylene

contain.

With particular advantage, the monomers C are selected from the group comprising methyl acrylate, ethyl acrylate, n-butyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, 2-propylheptyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, 2 -Propylheptyl methacrylate, styrene, vinyltoluene, 2-methylstyrene, 4-methylstyrene, 2-n-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene, vinyl acetate and vinyl propionate.

In the process according to the invention, the amount of monomers used is C> 80 and <99.8% by weight, advantageously> 90 and <99.5% by weight and particularly advantageously> 94 and <99% by weight.

Advantageously, therefore, for the inventive method

> 0.5 and <3% by weight of monomers A,

> 0.5 and <3 wt .-% of monomers B, and > 94 and <99% by weight of monomers C

used.

According to the invention, dispersants are used in the context of the present process which keep both the monomer droplets and the polymer particles formed dispersed in the aqueous medium and thus ensure the stability of the aqueous polymer dispersion produced. Suitable dispersants are both the protective colloids commonly used for carrying out free-radical aqueous emulsion polymerizations and emulsifiers.

Suitable protective colloids are, for example, polyvinyl alcohols, polyalkylene glycols, alkali metal salts of polyacrylic acids and polymethacrylic acids, gelatin derivatives or acrylic acid, methacrylic acid, maleic anhydride, 2-acrylamido-2-methylpropanesulfonic acid and / or 4-styrenesulfonic acid-containing copolymers and their alkali metal salts but also N-vinylpyrrolidone, N-vinylpyrrolidone, Vinylcaprolactam, N-vinylcarbazole, 1-vinylimidazole, 2-vinylimidazole, 2-vinylpyridine, 4-vinylpyridine, acrylamide, methacrylamide, acrylates containing amine groups, methacrylates, acrylamides and / or methacrylamides containing homopolymers and copolymers. A detailed description of other suitable protective colloids can be found in Houben-Weyl, Methods of Organic Chemistry, Volume XIV / 1, Macromolecular substances, Georg-Thieme-Verlag, Stuttgart, 1961, pages 41 1 to 420.

Of course, mixtures of protective colloids and / or emulsifiers can be used. Frequently, dispersants used are exclusively emulsifiers whose relative molecular weights, in contrast to the protective colloids, are usually below 1000. They may be anionic, cationic or nonionic in nature. Of course, in the case of the use of mixtures of surfactants, the individual components must be compatible with each other, which can be checked in case of doubt by hand on fewer preliminary tests. In general, anionic emulsifiers are compatible with each other and with nonionic emulsifiers. The same applies to cationic emulsifiers, while anionic and cationic emulsifiers are usually incompatible with each other. An overview of suitable emulsifiers can be found in Houben-Weyl, Methods of Organic Chemistry, Volume XIV / 1, Macromolecular Materials, Georg Thieme Verlag, Stuttgart, 1961, pages 192 to 208. According to the invention, however, the dispersants used are preferably exclusively emulsifiers.

Common nonionic emulsifiers are, for example, ethoxylated mono-, di- and tri-alkylphenols (EO degree: 3 to 50, alkyl radical: C ₄ to C 12) and also ethoxylated fatty alcohols (EO degree: 3 to 80, alkyl radical: Cs to C36). Examples are the Lutensol ^® A grades (C ₂ Ci4-fatty alcohol ethoxylates, EO units: 3 to 8), Lutensol ^® AO-marks (C13C15- oxo alcohol ethoxylates, EO units: 3 to 30), Lutensol ^® AT-marks ( Ci Ci ₆ ₈ - fatty alcohol ethoxylates, EO units: 1 1 to 80), Lutensol ^® ON brands (C10 oxo alcohol ethoxylates, EO units: 3 to 11) and the Lutensol ^® tO brands (C13 oxo alcohol ethoxylates, EO : 3 to 20) from BASF SE.

Typical anionic emulsifiers include alkali metal and ammonium salts of alkyl sulfates (alkyl radical: Cs to C12), ethoxylated sulfuric acid monoesters of alkanols (EO units: 4 to 30, alkyl radical: C12 to C ₈₎ and ethoxylated alkylphenols (EO units: 3 to 50, alkyl radical: C ₄ to C 12), of alkylsulfonic acids (alkyl radical: C 12 to Cis) and of alkylarylsulfonic acids (alkyl radical: Cg to Cis).

Further anionic emulsifiers further compounds of the general formula (I)

in which R ¹ and R ^{2 are} H atoms or C ₄ - to C 24 -alkyl and are not simultaneously H atoms, and M ¹ and M ^{2 may be} alkali metal ions and / or ammonium ions, has been found to be suitable. In the general formula (I), R ¹ and R ^{2 are} preferably linear or branched alkyl radicals having 6 to 18 C atoms, in particular having 6, 12 and 16 C atoms or hydrogen, where R ¹ and R ^{2 are} not both simultaneously H and Atoms are. M ¹ and M ² are preferably sodium, potassium or ammonium, with sodium being particularly preferred. Particularly advantageous compounds (I) are those in which M ¹ and M ^{2 are} sodium, R ^{1 is} a branched alkyl radical having 12 C atoms and R ^{2 is} an H atom or R ¹ . Frequently, technical mixtures are used which have a proportion of 50 to 90 wt .-% of the monoalkylated product, such as Dowfax ^® 2A1 (trademark of the Dow Chemical Company). The compounds (I) are well known, for example from US-A 4269749, and commercially available.

Suitable cationic emulsifiers are generally a C 1 to C 8 alkyl, alkylaryl or heterocyclic radical-containing primary, secondary, tertiary or quaternary ammonium salts, alkanolammonium salts, pyridinium salts, imidazolinium salts, oxazolinium salts, morpholinium salts, thiazolinium salts and salts of amine. oxides, quinolinium salts, isoquinolinium salts, tropylium salts, sulfonium salts and phosphonium salts. Examples include dodecylammonium acetate or the corresponding sulfate, the sulfates or acetates of the various 2- (N, N ₁ NT rimethyl- ammonium) ethylparaffinsäureester, N-Cetylpyridiniumsulfat, N-Laurylpyridiniumsulfat and N-cetyl-N, N, N-trimethylammonium sulfate, N -Dodecyl-N, N, N-trimethylammonium sulfate, N-octyl-N, N, N-trimethylammonium sulfate, N, N-distearyl-N, N-dimethylammonium sulfate and the gemini-surfactant N, N '- (lauryldimethyl ) ethylendiamindisulfat, ethoxylated tallow alkyl-N-methyl ammonium sulfate and ethoxylated oleylamine (for example Uniperol.RTM ^® AC from. BASF SE, about 12 ethylene oxide). Numerous other examples can be found in H. Stäche, Tensid-Taschenbuch, Carl-Hanser-Verlag, Munich, Vienna, 1981 and McCutcheon's, Emulsifiers & Detergents, MC Publishing Company, Glen Rock, 1989. It is favorable if the anionic counterparts are possible - Lows are low nucleophilic, such as perchlorate, sulfate, phosphate, nitrate and carboxylates, such as acetate, trifluoroacetate, trichloroacetate, propionate, oxalate, citrate, benzoate, and conjugated anions of organosulfonic acids, such as methyl sulfonate, trifluoromethylsulfonate and para-toluenesulfonate , furthermore tetrafluoroborate, tetraphenylborate, tetrakis (pentafluorophenyl) borate, tetrakis [bis (3,5-trifluoromethyl) phenyl] borate, hexafluorophosphate, hexafluoroarsenate or hexafluoroantimonate.

The emulsifiers preferably used as dispersants are advantageously in a total amount> 0.1 and <10 wt .-%, preferably> 0.1 and <5 wt .-%, in particular> 0.5 and <4 wt .-% , in each case based on the total amount of monomers used. The total amount of the protective colloids used as dispersants in addition to or instead of the emulsifiers is often> 0.1 and <10% by weight and frequently> 0.2 and <7% by weight, in each case based on the total monomer amount.

However, preference is given to using anionic and / or nonionic emulsifiers and particularly preferably anionic emulsifiers as dispersants.

According to the invention, at least a portion of the dispersants in the aqueous polymerization medium together with the total or partial amount of the monomers A and the subsets of the monomers B and C in polymerization stage 1 and the remaining amount optionally the aqueous polymerization medium in polymerization stage 2 discontinuously in one or more portions or continuously with constant or changing flow rates, in particular as a constituent of an aqueous monomer emulsion, containing the optionally remaining amount of the monomers A and the residual amounts of the monomers B and C, added. In this case, in polymerization stage 1, the amount of dispersing agent, in particular the emulsifiers chosen so that it> 1 mmol, preferably> 3 mmol and particularly preferably> 5 mmol and <25 mmol and preferably <20 mmol per 10 g of monomers A to C presented , In particular, in the preparation of polymer particles having a weight-average diameter <100 nm,> 3 and <20 mmol and preferably> 5 and <15 mmol of emulsifiers per 10 g of monomers A to C presented. These amounts of dispersant are significantly below the amounts (25 to 30 mmol) which are required in the preparation of correspondingly small polymer particles, if their preparation takes place without the hydrophobic monomers A.

The release of the free-radically initiated aqueous emulsion polymerization takes place by means of a free-radical polymerization initiator (free-radical initiator). In principle, these can be both peroxides and azo compounds. Of course, redox initiator systems come into consideration. As peroxides, in principle inorganic peroxides, such as hydrogen peroxide or peroxodisulfates, such as the mono- or di-alkali metal or ammonium salts of peroxodisulfuric, such as their mono- and di-sodium, potassium or ammonium salts or organic peroxides, such as alkyl hydroperoxides For example, tert-butyl, p-menthyl or cumyl hydroperoxide, as well as dialkyl or diarylperoxides, such as di-tert-butyl or Di. Cumyl peroxide can be used. As an azo compound substantially 2,2 - azobis (isobutyronitrile), ^2,2'-azobis (2,4-dimethylvaleronitrile), and 2,2 - azobis (amidinopropyl) dihydrochloride (AIBA, corresponding to V-50 from Wako Chemicals). Suitable oxidizing agents for redox initiator systems are essentially the abovementioned peroxides. Suitable reducing agents may be sulfur compounds having a low oxidation state, such as alkali metal sulphites, for example potassium and / or sodium sulphite, alkali hydrogen sulphites, for example potassium and / or sodium hydrogen sulphite, alkali metal metabisulphites, for example potassium and / or sodium metabisulphite, formaldehyde sulphoxylates, for example potassium and / or sodium formaldehyde. dehydesulfoxylate, alkali metal salts, especially potassium and / or sodium salts of aliphatic sulfinic acids and alkali metal hydrogensulfides, such as, for example, potassium and / or sodium hydrosulfide, salts of polyvalent metals, such as iron (II) sulfate, iron (II) ammonium sulfate, Iron (II) phosphate, endiols such as dihydroxymaleic acid, benzoin and / or ascorbic acid and reducing saccharides such as sorbose, glucose, fructose and / or dihydroxyacetone. In general, the amount of the radical initiator used, based on the total amount of monomers, 0.01 to 5 wt .-%, preferably 0.1 to 3 wt .-% and particularly preferably 0.2 to 1, 5 wt .-%.

According to the invention, the total amount of the radical initiator in the aqueous polymerization medium can be initially introduced prior to initiation of the polymerization reaction in polymerization stage 1. However, it is also possible, if appropriate, to initially introduce only a partial amount of the free-radical initiator in the aqueous polymerization medium prior to initiation of the polymerization reaction in polymerization stage 1 and then under polymerization conditions during the free radical emulsion polymerization according to the invention in polymerization stage 1 and polymerization stage 2, the total amount or the remaining amount remaining in accordance with the consumption discontinuously added in one or more portions or continuously with constant or changing flow rates.

Initiation of the polymerization reaction is understood to mean the start of the polymerization reaction of the monomers present in the aqueous polymerization medium after radical formation of the free-radical initiator. In this case, the initiation of the polymerization reaction can be carried out by adding radical initiator to the aqueous polymerization medium in the polymerization vessel under polymerization conditions. However, it is also possible that a partial or total amount of the free-radical initiator in the aqueous polymerization medium containing the monomers A to C present in the polyisocyanate. in polymerization stage 1 under conditions which are not suitable for initiating a polymerization reaction, for example at low temperature, and then polymerization conditions are set in the aqueous polymerization medium. Polymerization conditions are to be understood as meaning in general those temperatures and pressures under which the free-radically initiated aqueous emulsion polymerization proceeds at a sufficient rate of polymerization. They are dependent, in particular, on the radical initiator used. Advantageously, the nature and amount of the free radical initiator, the polymerization temperature and the polymerization pressure are selected so that there are always sufficient starting radicals available to initiate or maintain the polymerization reaction.

The reaction temperature for the novel free-radical aqueous emulsion polymerization is the entire range from 0 to 170 ^° C. In this case, temperatures of 50 to 120 ⁰ C, often 60 to 1 10 ⁰ C and often used 70 to 100 ⁰ C in the rule. The free-radical aqueous emulsion polymerization according to the invention can be carried out at a pressure of less than or equal to 1 atm (atmospheric pressure), such that the polymerization temperature can exceed 100 ^° C. and can be up to 170 ^° C. Preferably, volatile monomers such as ethylene, butadiene or vinyl chloride are polymerized under elevated pressure. The pressure may be 1, 2, 1, 5, 2, 5, 10, 15 bar (absolute) or even higher values. If emulsion polymerizations are carried out under reduced pressure, pressures of 950 mbar, often 900 mbar and often 850 mbar (absolute) are set. The free-radical aqueous emulsion polymerization according to the invention is advantageously carried out at 1 atm with exclusion of oxygen, for example under an inert gas atmosphere, for example under nitrogen or argon.

In principle, the aqueous reaction medium may also comprise minor amounts (<5% by weight) of water-soluble organic solvents, such as, for example, methanol, ethanol, isopropanol, butanols, pentanols, but also acetone, etc. However, the process according to the invention is preferably carried out in the absence of such solvents.

In addition to the abovementioned components, it is also possible optionally to use free-radical chain transfer compounds in the process according to the invention in order to reduce the molecular weight of the polymers obtainable by the polymerization. or control. These are essentially aliphatic and / or aliphatic halogen compounds, such as, for example, n-butyl chloride, n-butyl bromide, n-butyl iodide, methylene chloride, ethylene dichloride, chloroform, bromoform, bromotrichloromethane, dibromodichloromethane, carbon tetrachloride, carbon tetrabromide, benzyl chloride, benzyl bromide , organic thio compounds, such as primary, secondary or tertiary aliphatic thiols, such as ethanethiol, n-propanethiol, 2-propanethiol, n-butanethiol, 2-butanethiol, 2-methyl-2-propanethiol, n-pentanethiol, 2-pentanethiol, 3 Pentanethiol, 2-methyl-2-butanethiol, 3-methyl-2-butanethiol, n-hexanethiol, 2-hexanethiol, 3-hexanethiol, 2-methyl-2-pentanethiol, 3-methyl-2-pentanethiol, 4-methyl 2-pentanethiol, 2-methyl-3-pentanethiol, 3-methyl-3-pentanethiol, 2-ethylbutanethiol, 2-ethyl-2-butanethiol, n-heptanethiol and its isomeric compounds, n-octanethiol and its isomeric compounds, n Nonanthanethiol and its isomeric compounds, n-decanethiol and its isomeric Ve compounds, n-undecanethiol and its isomeric compounds, n-dodecanethiol and its isomeric compounds, n-tridecanethiol and its isomeric compounds, substituted thiols such as, for example, 2-hydroxyethanethiol, aromatic thiols such as benzenethiol, ortho, meta or para. Methylbenzenethiol, as well as all other in the Polymerhandbook 3 ^rd edtition, 1989, J. Brandrup and EH Immergut, John Wiley & Sons, Section II, pages 133 to 141 described sulfur compounds, but also aliphatic and / or aromatic aldehydes, such as acetaldehyde, propional dehyd and / or benzaldehyde, unsaturated fatty acids such as oleic acid, dienes with non-conjugated double bonds, such as divinylmethane or vinylcyclohexane or hydrocarbons with readily abstractable hydrogen atoms, such as toluene, are used. However, it is also possible to use mixtures of non-interfering radical-chain-transferring compounds mentioned above.

The total amount of radical-chain-transferring compounds optionally used in the process according to the invention, based on the total monomer amount, is generally <5% by weight, often <3% by weight and frequently <1% by weight.

Frequently, it is favorable if a partial or total amount of the radical chain transferring compound optionally used is fed to the aqueous polymerization medium prior to the initiation of the free radical emulsion polymerization in polymerization stage 1. However, it is particularly advantageous if a partial or total amount of the radical chain transferring compound optionally used is fed to the aqueous polymerization medium together with the monomers in the polymerization stage 2. It is essential to the invention that in the aqueous polymerization medium in polymerization stage 1> 50 wt .-%, preferably> 75 wt .-% and particularly advantageously the total amount of the monomers A but only> 0.1 and <10 wt .-%, preferably> 0, 1 and <5 wt .-% and particularly advantageously> 0.5 and <3 wt .-% of the total amounts of monomers B and monomers C are submitted and polymerized and then in polymerization 2, the remaining amount of the remaining monomers A as well as the remaining amounts of monomers B and monomers C are added to the aqueous polymerization medium under polymerization conditions and polymerized.

In this case, the dosage of any remaining amount of the monomers A and the residual amounts of the monomers B and C in polymerization stage 2 can be discontinuous in one or more portions or continuously with constant or changing flow rates. Preferably, the dosage of the

Monomers A to C continuously with constant flow rates. The residual amounts of the monomers A to C can also be metered in separate individual streams or as a monomer mixture. Preferably, the metering of any remaining amount of the monomers A and the residual amounts of monomers B and C is carried out as a monomer mixture, particularly advantageously in the form of an aqueous monomer emulsion. It is essential that, according to the invention, process variants should also be included in which the compositions of the respective monomers A, monomers B and / or monomers C change in polymerization stage 2, for example in a gradient or stepwise procedure familiar to the person skilled in the art.

With particular advantage, the process according to the invention takes place in such a way that the monomers A to C in polymerization stage 1 and in polymerization stage 2 up to a conversion of> 95 wt .-%, preferably> 98 wt .-% and particularly advantageously> 99 wt .-% be implemented. It is often advantageous if the aqueous polymer dispersion obtained after completion of the polymerization stage 2 is subjected to an aftertreatment to reduce the residual monomer content. The aftertreatment is carried out either chemically, for example by completing the polymerization reaction by using a more effective radical initiator system (so-called postpolymerization) and / or physically, for example by stripping the aqueous polymer dispersion with steam or inert gas. Appropriate Chemical and / or physical methods are familiar to the person skilled in the art [see, for example, EP-A 771328, DE-A 19624299, DE-A 19621027, DE-A 19741 184, DE-A 19741187, DE-A 19805122, DE-A 19828183, DE -A 19839199, DE-A 19840586 and 19847115]. The combination of chemical and physical after-treatment offers the advantage that in addition to the unreacted ethylenically unsaturated monomers, other interfering volatile organic compounds (the so-called VOCs [volatile organic compounds]) are removed from the aqueous polymer dispersion.

By deliberate variation of the nature and amount of the monomers A, B and C, it is possible for the person skilled in the art to prepare aqueous polymer dispersions whose polymers have a glass transition temperature or a melting point in the range from -60 to 270 ^° C. Of course, it is also possible to prepare multiphase or multiphase polymers having a plurality of glass transition temperatures. Depending on the intended use of the aqueous polymer dispersions polymers are prepared which have at least one polymer phase whose glass transition temperature> -60 and <10 ⁰ C (adhesives),> 10 and <100 ⁰ C (binder for coating formulations) or> 80 ⁰ C (hard Paint films).

By the glass transition temperature T ₉ , it is meant the glass transition temperature limit which it strives for with increasing molecular weight, according to G. Kanig (Kolloid-Zeitschrift & Zeitschrift fur Polymere, vol. 190, page 1, equation 1). The glass transition temperature or the melting point is determined by the DSC method (differential scanning calorimetry, 20 K / min, midpoint measurement, DIN 53765).

According to Fox (TG Fox, Bull. Am. Phys Soc., 1956 [Ser. II] 1, page 123 and according to LJllmann's Encyclopedia of Industrial Chemistry, Vol. 19, page 18, 4th edition, Verlag Chemie, Weinheim, 1980) applies to the glass transition temperature of at most weakly crosslinked copolymers in a good approximation:

1 / Tg = XVTg ¹ + X ² / Tg ² + .... X ⁿ / T _g ",

where x ¹ , x ² , .... x ⁿ the mass fractions of the monomers 1, 2, .... n and T ₉ ¹ , T ₉ ² , .... T ₉ "the glass transition temperatures of each of only one of Monomers 1, 2, .... n of polymers prepared in degrees Kelvin.The T ₉ values for the homopolymers of most monomers are known and are described, for example, in Ullmann's Ecyclopedia of Indus- trial Chemistry, Vol. 5, Vol. A21, page 169, VCH Weinheim, 1992; Other sources of glass transition temperatures of homopolymers are, for example, J. Brandrup, EH Immergut, Polymer Handbook, 1 ^st Ed., J. Wiley, New York 1966, 2 ^nd Ed. J. Wiley, New York 1975, and 3 ^rd Ed. J. Wiley, New York 1989).

The aqueous polymer dispersions obtained according to the invention usually have polymer solids contents of> 10 and <70% by weight, frequently> 20 and <65% by weight and often> 40 and <60% by weight, based in each case on the aqueous polymer dispersion.

The aqueous polymer dispersions obtainable by the process according to the invention have polymer particles which have a narrow particle size distribution and weight-average diameters D _w in the range> 10 and <500 nm, preferably> 20 and <200 nm and particularly preferably> 30 nm to <100 nm. The determination of the weight-average particle diameter is known to the person skilled in the art and is carried out, for example, by the method of the analytical ultracentrifuge. By weight-average particle diameter is in this document as determined by the method of the analytical ultracentrifuge weight-average D _w as value understood (see. This SE Harding et al., Analytical ultracentrifugation in Biochemistry and Polymer Science, Royal Society of Chemistry, Cambridge, Great Britain 1992 , Chapter 10, Analysis of Polymer Dispersions with an Eight Cell AUC Multiplexer: High Resolution Particle Size Distribution and Density Gradient Techniques, W. Mächtle, pages 147 to 175).

A narrow particle size distribution should be understood within the scope of this document if the ratio of the weight-average particle diameter D _w determined by the method of the analytical ultracentrifuge and number-average particle diameter DN 50 [D _W 5O / DN 50] <2.0, preferably <1.5 preferably <1, 2 or ≤ 1, 1.

The aqueous polymer dispersions having narrow particle size distributions and weight-average particle diameters Dw <100 nm which are obtainable by the process according to the invention have a surprisingly high transparency and are therefore particularly suitable as binders in transparent aqueous formulations for wood coatings. The still moist coatings have the clarity desired by the user. In addition, benefits often show up, like one less need for thickeners to set a specific viscosity. In particular, the coating formulations have a good and deep coloration, a good penetration of the formulation into the wood surface and a good "initiation" of the wood grain with the use of color pigments In addition, the novel aqueous polymer dispersions have improved filterability and reduced coagulum contents in comparison to corresponding not according to the invention aqueous polymer dispersions.

It is also important that in particular in the preparation of polymer particles having a particle diameter <100 nm by the process according to the invention significantly lower amounts of dispersant, in particular smaller amounts of emulsifier are required, than when a corresponding aqueous emulsion polymerization process without the hydrophobic monomers A performed becomes.

Of course, the aqueous polymer dispersions of the invention which are obtainable by the process according to the invention can be used as a component in the production of adhesives, sealants, plastic plasters, paper coating slips, fiber webs, paints and coating compositions for organic substrates and for the modification of mineral binders.

Furthermore, the corresponding polymer powders can be obtained in a simple manner from the novel aqueous polymer dispersions (for example by freeze drying or spray drying). These polymer powders obtainable in accordance with the invention can also be used as a component in the production of adhesives, sealants, plastic plasters, paper coating slips, fiber webs, paints and coating compositions for organic substrates and for the modification of mineral binders.

The invention will be illustrated by the following non-limiting examples.

Examples

a) Preparation of aqueous polymer dispersions

Example 1 (B1) In a equipped with dosing and temperature control polymerization were at 20 to 25 ⁰ C (room temperature) under nitrogen atmosphere

286.9 g of deionized water and

50.0 g of a 15% strength by weight aqueous solution of sodium lauryl sulfate

initially charged and heated to 82 ⁰ C with stirring. Upon reaching this temperature, 12.2 g of octene-1, 22.8 g of feed 1 and then while maintaining the temperature of 2.9 g of feed 2 was added and stirred for 5 minutes. Thereafter, starting at the same time, the residual quantities of feed 1 and feed 2 were continuously metered in over the course of 165 minutes, each time with constant amounts.

Feed 1 (homogeneous mixture of): 781.3 g of deionized water

50.0 g of a 15% strength by weight aqueous solution of sodium lauryl sulfate

498.0 g of n-butyl acrylate

470.0 g of methyl methacrylate

9.8 g of a 50% strength by weight aqueous solution of acrylamide 14.9 g of acrylic acid

Feed 2 (homogeneous solution off): 26.6 g of deionized water and 2.0 g of sodium peroxodisulfate

After completion of feeds 1 and 2, the feed lines were each purged with 24 g of deionized water. The polymerization was allowed to react for one further 30 minutes at 82 ⁰ C. Subsequently, 16.0 g of a 5 wt .-% aqueous hydrogen peroxide solution and a solution of 1.4 g of ascorbic acid and 14 g of deionized water were added to the polymerization mixture simultaneously over a period of 60 minutes with constant flow rates starting from separate feed lines and The resulting mixture is stirred for 15 minutes. The aqueous polymer dispersion obtained was then cooled to room temperature, mixed with 8.4 g of a 25% strength by weight aqueous ammonia solution and filtered through a 125 μm filter. The aqueous polymer dispersion obtained had a solids content of 44.1% by weight. The weight-average particle diameter of the polymer particles was 52 nm; the polydispersity DWSO / DNSO was found to be 1.20. The coagulum content was <0.1% by weight. The diluted with deionized water to a solids content of 40 wt .-% aqueous polymer dispersion had a light transmittance of 12%.

The solids content was generally determined by drying a defined amount of the aqueous polymer dispersion (about 1 g) in an aluminum crucible with an inner diameter of about 5 cm at 140 ^° C. in a drying oven to constant weight. Two separate measurements were made. The values given in the examples represent the mean value of the respective two measurement results.

The coagulate was generally determined by the 125 micron filter after filtration tion was rinsed with 100 ml of deionized water and then dried for 30 minutes at 140 ⁰ C in a drying cabinet. The values given in each case relate to the solids content of the particular aqueous polymer dispersion.

The determination of the weight-average particle diameter and the polydispersity were generally carried out by the method of analytical ultracentrifuge (see, for this purpose, SE Harding et al., Analytical Ultracentrifugation in Biochemistry and Polymer Science, Royal Society of Chemistry, Cambridge, Great Britain 1992, Chapter 10, Analysis of Polymer Dispersions with Eight-Cell AUC Multiplexers: High Resolution Particle Size Distribution and Density Gradient Techniques, W. Mächtle, pages 147-175).

The light transmission was generally determined by means of a sample of the aqueous polymer dispersion diluted to a polymer solids content of 40% by weight with deionized water using a spectrophotometer DR / 2010 from Hach, Germany.

Example 2 (B2)

In a equipped with dosing and temperature control polymerization vessel were at room temperature under a nitrogen atmosphere

286.9 g of deionized water and 50.0 g of a 15% strength by weight aqueous solution of sodium lauryl sulfate

initially charged and heated to 82 ⁰ C with stirring. Upon reaching this temperature, 9.1 g of octene-1, 28.7 g of feed 1 and then while maintaining the temperature 2.9 g of feed 2 was added and stirred for 5 minutes. At the same time, the remaining amount of feed 1 and the total amount of feed 1a were homogeneously mixed, and then, at the same time, the remaining amounts of mixed feed 1/1 a and feed 2 were continuously metered in within 165 minutes, each with constant flow rates.

Feed 1 (homogeneous mixture of): 781, 6 g of deionized water

50.0 g of a 15% strength by weight aqueous solution of sodium lauryl sulfate 498.0 g of n-butyl acrylate 470.0 g of methyl methacrylate

Feed 1a: 3.1 g of octene-1

After completion of the feeds 1 / 1a and 2, the feed lines were each rinsed with 24 g of deionized water. The polymerization was allowed to react for one further 30 minutes at 82 ⁰ C. Subsequently, 16.0 g of a 5% strength by weight aqueous hydrogen peroxide solution and a solution of 1.4 g of ascorbic acid and 14 g of deionized water were continuously introduced into the polymerization mixture at the same time over 60 minutes with constant flow rates added and the resulting mixture is stirred for 15 minutes. Subsequently, the resulting aqueous polymer dispersion was cooled to room temperature, admixed with 8.4 g of a 25% strength by weight aqueous ammonia solution and filtered through a 125 μm filter. The aqueous polymer dispersion obtained had a solids content of 44.8% by weight. The weight-average particle diameter of the polymer particles was 54 nm; the polydispersity DWSO / DNSO was found to be 1.18. The coagulum content was <0.1% by weight. The diluted with deionized water to a solids content of 40 wt .-% aqueous polymer dispersion had a light transmittance of 11%.

Comparative Example 1 (V1)

The preparation of Comparative Example 1 was carried out analogously to the preparation of Example 2 with the difference that 6.0 g of octene-1 and 34.5 g of feed 1 were introduced and feed 1 a from 6.2 g of octene-1 instead of 3, 1 Octen-1 existed.

The aqueous polymer dispersion obtained had a solids content of 44.0% by weight. The coagulum content was 0.3% by weight. The weight-average particle diameter of the polymer particles was 57 nm; the polydispersity DWSO / DNSO was found to be 2.6. The aqueous polymer dispersion diluted to a solids content of 40% by weight with deionized water had a light transmittance of 5%.

Comparative Example 2 (V2)

The preparation of Comparative Example 2 was carried out analogously to the preparation of Example 2 with the difference that 3.1 g of octene-1 and 39.8 g of feed 1 were initially charged and feed 1 a from 9.1 g of octene-1 instead of 3, 1 Octen-1 existed.

The aqueous polymer dispersion obtained had a solids content of 44.9% by weight. The coagulum content was 0.3% by weight. The weight-average particle diameter of the polymer particles was 57 nm; the polydispersity DWSO / DNSO was found to be 1.33. The aqueous polymer dispersion diluted with deionized water had a light transmittance of 6%.

Comparative Example 3 (V3)

The preparation of Comparative Example 3 was carried out analogously to the preparation of Example 2 with the difference that only 45.5 g of feed 1 were introduced and feed 1a from 12.2 g of octene-1 instead of 3.1 octene-1. The aqueous polymer dispersion obtained had a solids content of 44.4% by weight. The coagulum content was 0.4% by weight. The weight-average particle diameter of the polymer particles was 60 nm; the polydispersity DWSO / DNSO was found to be 2.93. The aqueous polymer dispersion diluted with deionized water had a light transmittance of 1%.

Comparative Example 4 (V4)

The preparation of Comparative Example 4 was carried out analogously to the preparation of Example 1 with the difference that now 24.5 g octene-1 and no feed 1 were submitted, and that feed 1 from a homogeneous mixture of:

781, 5 g of deionized water 50.0 g of a 15 wt .-% aqueous solution of sodium lauryl sulfate

492.0 g of n-butyl acrylate

464.3 g of methyl methacrylate

9.8 g of a 50% strength by weight aqueous solution of acrylamide

14.8 g of acrylic acid

duration.

The aqueous polymer dispersion obtained had a solids content of 44.2% by weight. The coagulum content was 0.5% by weight. The weight-average particle diameter of the polymer particles was 48 nm; the polydispersity DWSO / DNSO was found to be 1.37. The aqueous polymer dispersion diluted with deionized water had a light transmittance of 2%.

Comparative Example 5 (V5)

The preparation of Comparative Example 5 was carried out analogously to the preparation of Example 1 with the difference that now only 45.3 g of feed 1 and no octene-1 was initially charged, and that feed 1 from a homogeneous mixture of:

781, 5 g of deionized water

50.0 g of a 15% strength by weight aqueous solution of sodium lauryl sulfate 504.0 g of n-butyl acrylate

475.7 g of methyl methacrylate

10.2 g of a 50 wt .-% aqueous solution of acrylamide

15.2 g of acrylic acid

duration.

The aqueous polymer dispersion obtained had a solids content of 44.5% by weight. The coagulum content was 0.4% by weight. The weight-average particle diameter of the polymer particles was 60 nm; the polydispersity DWSO / DNSO was found to be 2.82. The aqueous polymer dispersion diluted with deionized water had a light transmittance of 2%.

b) Application engineering studies

The aqueous polymer dispersions B1 and B2 and also V1 to V5 were each diluted with deionized water to a solids content of 37.5% by weight. 163 g each of these dilute aqueous polymer dispersions were at room temperature as a binder to a Rohstreichlasurformulierung consisting of

22.4 g of deionized water

2.0 g Mergal® S 96 (fungicide from Troy Chemie GmbH) 0.2 g AMP® 90 (neutralizing agent from Angus Chemical Company) 0.2 g silicone surfactant Byk 346 (wetting agent from Byk-Chemie GmbH ) 0.4 g Tego Foamex® 810 (defoamer from Tego Chemie Service

GmbH) 1, 0 g Coatex® BR 100 P (thickener from Cognis Deutschland GmbH & Co

KG)

6.0 g Luconyl® yellow liquid (pigment from BASF SE) 5.0 g Texanol® (solvent from Eastman Germany)

added and mixed homogeneously.

The resulting coating stains were uniformly uniformly applied to a surface of untreated 15 cm × 7 cm pinewood boards (thickness: 0.5 cm) at room temperature using a mounting device with a 300 μm gap width, which had previously been ground. the. The glazed boards thus obtained were then dried in a climate chamber at 23 ⁰ C and 50% relative humidity for 24 hours. The coating stains applied to the wood surfaces were visually evaluated in wet and dried conditions for color depth and color brilliance. The evaluation was based on the school grading system, where 1 is very good, 2 is good, 3 is satisfactory, 4 is sufficient and 5 is insufficient. The results obtained in the individual assessments are listed in the following table:

Example B1 B2 V1 V2 V3 V4 V5

Color depth moist 1 1-2 3-4 3 5 5 4-5

Color brilliance moist 1 1-2 3-4 3-4 4-5 5 5

Color depth dry 1-2 1-2 2 2 2 2 2

Color brilliance dry 1-2 2 2 1-2 2 1-2 1-2

Comment (clear clear slightly slightly milky milky, milky ter order) tarnished clouded streaks

From the results it is clearly evident that the color depth and color brilliance of the color glazes which were produced using the aqueous polymer dispersions B1 and B2 according to the invention were assessed significantly better, especially in the wet state.

Claims

Process for the preparation of an aqueous polymer dispersion Patent claims

1. A process for the preparation of an aqueous polymer dispersion by free-radically initiated aqueous emulsion polymerization of ethylenically unsaturated monomers in the presence of at least one dispersant and at least one free-radical initiator, characterized in that for the emulsion

> 0.1 and <10 wt .-% of at least one 4 to 40 carbon atoms having

Alkenes [monomers A],

> 0.1 and <10 wt .-% of at least one ethylenically unsaturated monomer having a solubility> 200 g per 1000 g entio- nisiertem water at 20 ⁰ C and 1 atm (absolute) [monomers B], and

> 80 and <99.8 wt .-% having a solubility of <100 g per 1000 g of deionized water at 20 ⁰ C of at least one ethylenically unsaturated monomers and 1 atm (absolute) [Mo nomere C]

are used and add the monomers A to C to 100 wt .-%, wherein in an aqueous polymerization at first only

> 50% by weight of the total amount of the at least one monomer A,

> 0.1 and <10 wt .-% of the total amount of the at least one monomer B, and

> 0.1 and <10% by weight of the total amount of the at least one monomer C

and subsequently the residual amounts of the monomers A to C are added to the aqueous polymerization medium under polymerization conditions and polymerized (polymerization stage 2).

2. The method according to claim 1, characterized in that the monomers A to C are added continuously in polymerization stage 2.

3. The method according to any one of claims 1 and 2, characterized in that the monomers A to C are added in polymerization stage 2 as a monomer mixture.

4. The method according to any one of claims 1 to 3, characterized in that in polymerization stage 1, the total amount of the at least one monomer A are submitted.

5. The method according to any one of claims 1 to 4, characterized in that in the polymerization stage 1, the amount of dispersant> 1 mmol per 10 g of monomers.

6. The method according to any one of claims 1 to 5, characterized in that the monomers A are selected from the group comprising octene-1, nonene-1, decene-1, undecene-1 and / or dodecene-1.

7. The method according to any one of claims 1 to 6, characterized in that the monomers B are selected from the group consisting of acrylic acid, methacrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, vinylsulfonic acid, acrylamide, methacrylamide, N- (2-Methacryloyloxyethyl ) ethyleneurea, N- (2-acryloyloxyethyl) ethylene urea, 2-acetoacetoxyethyl acrylate, 2-

Acetoacetoxyethyl methacrylate, diacetone acrylamide, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, 2-hydroxyethyl methacrylate and hydroxypropyl methacrylate.

8. The method according to any one of claims 1 to 7, characterized in that the monomers C are selected from the group comprising methyl acrylate, ethyl acrylate, n-butyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, 2-propylheptyl acrylate, methyl methacrylate, ethyl methacrylate , n-butyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, 2-propylheptyl methacrylate, styrene, vinyltoluene, 2-methylstyrene, 4-methylstyrene, 2-n-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene, Vinyl acetate and vinyl propionate.

9. The method according to any one of claims 1 to 8, characterized in that emulsifiers are used as dispersants.

10. The method according to any one of claims 1 to 9, characterized in that nonionic and / or anionic emulsifiers are used as dispersants.

1 1. A method according to any one of claims 1 to 10, characterized in that for the emulsion polymerization

> 0.5 and <3% by weight of monomers A,

> 0.5 and <3 wt .-% of monomers B, and

> 94 and <99% by weight of monomers C

be used.

12. Aqueous polymer dispersion obtainable by a process according to any one of claims 1 to 11.

13. Polymer powder obtainable by drying an aqueous polymer dispersion according to claim 12.

14. Use of an aqueous polymer dispersion according to claim 12 or a polymer powder according to claim 13 for the preparation of adhesives, sealants, plastic plasters, paper coating slips, nonwoven fabrics, paints and coating compositions for organic substrates and for the modification of mineral binders.