EP4146714A1

EP4146714A1 - Polyvinyl-alcohol-stabilized (meth)acrylic acid ester polymers

Info

Publication number: EP4146714A1
Application number: EP20725120.8A
Authority: EP
Inventors: Hans-Peter Weitzel; Ulf Dietrich
Original assignee: Wacker Chemie AG
Current assignee: Wacker Chemie AG
Priority date: 2020-05-05
Filing date: 2020-05-05
Publication date: 2023-03-15
Also published as: US20230202924A1; CN115515994A; CN115515994B; WO2021223849A1

Abstract

The invention relates to polyvinyl-alcohol-stabilized (meth)acrylic acid ester polymers having particles sizes Dw of 100 to 900 nm, in the form of aqueous dispersions or in the form of powders that can be redispersed in water, characterized in that the (meth)acrylic acid ester polymers are based on a) 1 to 30 wt.% of one or more vinyl esters of carboxylic acids having 5 to 15 C atoms, b) 20 to 80 wt.% of one or more (meth)acrylic acid esters, the homopolymer of which has a glass transition temperature Tg of ≤ 20°C, c) 10 to 70 wt.% of one or more (meth)acrylic acid esters, the homopolymer of which has a glass transition temperature Tg of ≥ 50°C, and optionally one or more additional ethylenically unsaturated monomers, the specifications in wt.% relating to the total weight of the (meth)acrylic acid ester polymers.

Description

Polyvinyl alcohol stabilized (meth) acrylic acid ester polymers

The invention relates to polyvinyl alcohol-stabilized (meth) acrylic acid ester polymers in the form of aqueous dispersions or water-redispersible powders, processes for their manufacture and their use in construction chemical products such as tile adhesives, leveling compounds, powder paints or thermal insulation composite systems.

Aqueous dispersions or water-redispersible powders of polymers based on ethylenically unsaturated monomers are used in a wide variety of applications, for example in adhesives, coating applications, as binders in carpet, textile and paper applications and in construction chemical products such as tile adhesives, plasters and sealants. Such polymer dispersions are usually prepared by aqueous emulsion polymerization of ethylenically unsaturated monomers, for example batchwise (discontinuously) in stirred polymerization reactors or else continuously, for example in stirred tank cascades. Dispersion powders can be prepared by spray drying aqueous polymer dispersions with the addition of drying aids, such as polyvinyl alcohol, as described, for example, in DE-A 2049114. Free-flowing powders obtainable in this way with particle sizes between 10 and 250 gm redisperse in water again to form dispersions with particle sizes between 0.1 and 5 gm. H. they must not tend to sit down.

Aqueous polymer dispersions are usually stabilized with protective colloids, such as polyvinyl alcohol, or emulsifiers with a variety of chemicals. In the case of vinyl acetate copolymers, polyvinyl alcohol is often used as a protective colloid in order to obtain both stable polymer dispersions and redispersible dispersion powders with the desired powder properties. In contrast, in the case of conventional (meth) acrylic acid ester copolymers, the stabilization with conventional polyvinyl alcohols have not been tried and tested, since dispersions of this type are not sufficiently stable or coarse polymer particles are often formed, which must be prevented.

In order to avoid such problems in the case of (meth) acrylic acid ester copolymers, emulsifiers were often used as stabilizers. However, emulsifiers can be problematic from an ecological or health point of view, for example because of their irritating or sensitizing effect, so that end products containing appropriate emulsifiers can harm consumers or even have to be labeled as hazardous substances. There is therefore a desire to dispense with emulsifiers as stabilizers.

So far, very special, modified polyvinyl alcohols have been used as protective colloids for stabilizing (meth) acrylic acid esters. For this purpose, JP2004 339291, JP2004323571, JP2004331785, JP07070989 and JP05059106 describe mercapto-functional polyvinyl alcohols. WO2006095524 teaches polyvinyl alcohols with a defined proportion of 1.2 glycol groups. With the special synthesis strategies of DE19928933 stable, but only coarse (meth) acrylic acid ester polymer dispersions could be obtained. Such special, modified polyvinyl alcohols are on the one hand complex to produce and expensive. In addition, such functional groups introduced into polyvinyl alcohol can have a negative effect on the processability or other properties of the application products.

Against this background, the object was to provide finely divided, stable, protective colloid-stabilized aqueous dispersions of (meth) acrylic acid ester polymers and corresponding powders redispersible in water, the protective colloids used should be as conventional, unmodified polyvinyl alcohols as possible. In addition, such aqueous dispersions or powders redispersible in water should be accessible by established methods that are as simple as possible. The invention relates to polyvinyl alcohol-stabilized (meth) acrylic ester polymers with particle sizes Dw from 100 to 900 nm in the form of aqueous dispersions or powders redispersible in water, characterized in that the (meth) acrylic ester polymers are based on a) 1 to 30 wt. % of one or more vinyl esters of carboxylic acids with 5 to 15 carbon atoms, b) 20 to 80% by weight of one or more (meth) acrylic acid esters, the homopolymer of which has a glass transition temperature Tg of <20 ° C, c) 10 to 70% by weight of one or more (meth) acrylic acid esters whose homopolymers have a glass transition temperature Tg of> 50 ° C., and optionally one or more other ethylenically unsaturated monomers, the data being in% by weight refer to the total weight of the (meth) acrylic acid ester polymers.

(Meth) acrylic acid ester polymers generally include acrylic acid ester polymers or methacrylic acid ester polymers, and preferably copolymers of acrylic acid esters and methacrylic acid esters.

(Meth) acrylic acid esters generally stand for acrylic acid esters and methacrylic acid esters.

Vinyl esters of carboxylic acids having 9 to 12 carbon atoms are preferred as vinyl esters a).

Examples of vinyl esters a) are vinyl 2-ethylhexanoate, vinyl laurate, vinyl pivalate and vinyl esters of alpha-branched monocarboxylic acids with 5 to 13 carbon atoms, such as VeoVa9R, VeoValOR, VeoVallR or VeoVal2R (trade names of the company Hexion). Vinyl esters of alpha-branched monocarboxylic acids having 9 to 13 carbon atoms and in particular vinyl laurate are preferred.

The (meth) acrylic ester polymers are preferably based on 3 to 25% by weight, particularly preferably 5 to 20% by weight and most preferably 10 to 15% by weight on vinyl ester a), based on the total weight of the (meth) Acrylic acid ester polymers. (Meth) acrylic acid esters b) whose homopolymers have a glass transition temperature Tg of <10 ° C. are preferred.

(Meth) acrylic acid esters b) can be, for example, (meth) acrylic acid esters of linear or branched, Ci- to Cis-alkanols, in particular Ci- to Cis-alkanols. Examples of such alkanols are n-propyl, n-butyl, iso-butyl, n-pentyl, n-hexyl, n-nonyl or n-decyl alkanols.

Preferred (meth) acrylic acid esters b) are n-butyl acrylate, n-hexyl acrylate, n-hexyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate and stearyl acrylate. Most preferred is butyl acrylate, especially n-butyl acrylate.

The (meth) acrylic acid ester polymers are preferably based on (meth) acrylic acid esters b) to the extent of 25 to 70% by weight, particularly preferably 30 to 65% by weight and most preferably 40 to 60% by weight, based on the total weight of the (Meth) acrylic acid ester polymers.

(Meth) acrylic acid esters c) whose homopolymers have a glass transition temperature Tg of> 60 ° C., in particular> 80 ° C., are preferred.

(Meth) acrylic acid esters c) can be, for example, (meth) acrylic acid esters of linear or branched, Ci- to Cio-alkanols, in particular Ci- to Cio-alkanols.

Preferred (meth) acrylic acid esters c) are methyl methacrylate, tert-butyl methacrylate and tert-butyl acrylate. Methyl methacrylate is particularly preferred.

The (meth) acrylic acid ester polymers are preferably based on (meth) acrylic acid esters c) to the extent of 15 to 60% by weight, particularly preferably 20 to 55% by weight and most preferably 25 to 50% by weight, based on the total weight of the (Meth) acrylic acid ester polymers The (meth) acrylic ester polymers are preferably based to 50 to 99 wt .-%, particularly preferably 65 to 97 wt .-% and most preferably 80 to 95 wt .-% on (meth) acrylic acid esters b) and (meth) acrylic acid esters c ), each based on the total weight of the (meth) acrylic acid ester polymers.

The other monomers are generally different from the monomers a) to c).

Other monomers are, for example, ethylenically unsaturated

1 2

Silanes d), such as compounds of the general formula R SiR (OR), where R ^{2 is} a Ci- to C ₃ -alkyl radical, Ci- to C ₃ -alkoxy radical or halogen, for example chlorine or bromine, R is CH ₂ = CR ⁴ - (CH ₂ ) _0-1 or CH ₂ = CR ⁴ C0 ₂ (CH ₂ ) _{1 3} with R ⁴ as a carbon radical with 1 to 10 carbon atoms, R ^{3 is} an unbranched or branched, optionally substituted alkyl radical with 1 to 12 carbon atoms, preferably 1 to 3 carbon atoms. The silicon atom Si is known to be tetravalent.

Preferred are g-acrylic or g-methacryloxypropyltri (alkoxy) silanes, a-methacryloxymethyltri (alkoxy) silanes, g-methacryloxypropylmethyldi (alkoxy) silanes, vinylalkyldi (alkoxy) silanes and vinyltri (alkoxy) silanes, methoxy, ethoxy, isopropoxy, methoxyethylene, ethoxyethylene, methoxypropylene glycol ether or ethoxypropylene glycol ether radicals, for example, can be used as alkoxy groups.

Particularly preferred are vinyltrimethoxysilane, Vinylmethyldime- thoxysilan, vinyltriethoxysilane, vinylmethyldiethoxysilane, nyltripropoxysilan Vi, vinyltriisopropoxysilane, vinyltris (1-me thoxy) -isopropoxysilan, vinyltributoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, methacryloxymethyltrimethoxysilane, 3-methacryloxypropyl-tris ( 2- methoxyethoxy) silane, vinyltris- (2-methoxyethoxy) silane, allylvi- nyltrimethoxysilane, allyltrimethoxysilane, vinyldimethylmethoxysilane, vinyldimethylethoxysilane, vinylisobutyldimethoxysilane, vinyltriisopropyloxysilane, vinyltributoxysilane hexyloxysilane, vinylmethoxydihexyloxysilane, vinyltrioctyloxysilane, vinyldimethoxyoctyloxysilane, vinylmethoxydioctyloxysilane, vinylmethoxydilauryloxysilane and vinyldimethoxylauryloxysilane. Most preferred are vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinylmethyldiethoxysilane, vinyltris- (1-methoxy) -isopoxysilane, methacryloxypropyl-tris (2-methoxyethoxy) silane, methacryloxypropyl-tris (2-methoxyethoxy) silane, 3-methoxy-methoxy-silane, 3-methoxyethoxy-silane, 3-methoxyethoxy-silane, 3-methoxyethoxy-silane, 3-methoxy-ethoxy-silane, 3-methoxyethoxy-silane, 3-methoxy-ethoxy-silane, 3-methoxy-ethoxy-silane, 3-methoxy-ethoxy-silane, vinyltriisopropoxy-silane, vinyltriisopropoxy-silane, 3-methoxyethoxy-silane, 3-methoxyethoxy Methacryloxymethyltrimethoxysilane. Vinyl silanes, ie silanes containing vinyl groups, are given before.

The (meth) acrylic ester polymers are preferably based on 0 to 5% by weight, particularly preferably 0.1 to 3% by weight and most preferably 0.5 to 1% by weight, based on ethylenically unsaturated silanes d) the total weight of the (meth) acrylic acid ester polymers.

Further monomers are, for example, epoxy-functional, ethylenically unsaturated monomers e), in particular glycidyl methacrylate and glycidyl acrylate.

The (meth) acrylic acid ester polymers are based preferably from 0 to 5% by weight, particularly preferably from 0.1 to 3% by weight and most preferably from 0.5 to 2% by weight, based on monomers e), based on the total weight of (meth) acrylic acid ester polymers.

Examples of further monomers are also one or more ethylenically unsaturated monomers f) selected from the group comprising vinyl esters of carboxylic acids having 2 to 4 carbon atoms, olefins, dienes, vinyl aromatics and vinyl halides.

Examples of vinyl esters f) are vinyl propionate, vinyl butyrate, 1-methyl vinyl acetate and, in particular, vinyl acetate. Preferred olefins or dienes are ethylene, propylene and 1,3-butadiene. Preferred vinyl aromatics are styrene and vinyl toluene. A preferred vinyl halide is vinyl chloride. Monomers f), in particular vinyl esters of carboxylic acids having 2 to 4 carbon atoms and / or ethylene, are preferably 0 to 20% by weight and particularly preferably 0.1 to 10% by weight in the (meth) acrylic acid ester polymers , based on the total weight of the (meth) acrylic acid ester polymers. Most preferably, the (meth) acrylic acid ester polymers contain no monomer unit f), in particular no vinyl ester unit f) and / or no ethylene unit.

The further monomers optionally also comprise 0 to 20% by weight, preferably 0.5 to 10% by weight, based on the total weight of the (meth) acrylic acid ester polymers, of one or more auxiliary monomers g). Examples of auxiliary monomers g) are ethylenically unsaturated mono- and dicarboxylic acids, preferably acrylic acid, methacrylic acid, fumaric acid and maleic acid; ethylenically unsaturated carboxamides and nitriles, preferably acrylamide and acrylonitrile; Mono- and diesters of fumaric acid and maleic acid such as the diethyl and diisopropyl esters, as well as maleic anhydride, ethylenically unsaturated sulfonic acids or their salts, preferably vinylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid. Further examples are pre-crosslinking comonomers such as multiply ethylenically unsaturated comonomers, for example divinyl adipate, diallyl maleate, allyl methacrylate or triallyl cyanurate, or postcrosslinking comonomers, for example acrylamidoglycolic acid (AGA), methylacrylamidoglycol, methyl acrylamide (N-methacrylamide), methyl-methyl-ester (MAGME) -methacrylamide (N-methylol) (NMMA), N-methylol allyl carbamate, alkyl ethers such as isobutoxy ether or esters of N-methylol acrylamide, N-methylol methacrylamide and N-methylol allyl carbamate. Monomers with hydroxy or CO groups may also be mentioned, for example methacrylic acid and acrylic acid hydroxyalkyl esters such as hydroxyethyl, hydroxypropyl or hydroxybutyl acrylate or methacrylate, and compounds such as diacetone acrylamide and acetoxyethyl acrylate or methacrylate. Further examples are also vinyl ethers, such as methyl, ethyl or isobutyl vinyl ether. The (meth) acrylic ester polymers preferably contain no carboxamide unit g), in particular no acrylamide unit. The (meth) acrylic ester polymers particularly preferably contain no unit of monomers from the group comprising acrylamidoglycolic acid (AGA), methyl acrylamidoglycolic acid (MAGME), N-methylolacrylamide (NMA), N-methylol methacrylamide (NMMA), N-methylol allyl carbamate, alkyl ethers such as the isobutoxy ether or ester of N-methylol acrylamide, N-methylol methacrylamide and N-methylol allyl carbamate.

Preferred further monomers are ethylenically unsaturated silanes d) and epoxy-functional, ethylenically unsaturated monomers e).

Further monomers are preferably 0 to 20% by weight, particularly preferably 0.1 to 10% by weight and most preferably 1 to 5% by weight, polymerized into the (meth) acrylic acid ester polymers, based on the total weight of the ( Meth) acrylic acid ester polymers.

The (meth) acrylic acid ester polymers have weight-average particle diameters Dw between 100 nm and 900 nm, preferably 200 nm to 800 nm and particularly preferably 250 nm and 800 nm.

The polydispersity PD of the (meth) acrylic acid ester polymers is preferably <3, particularly preferably <2.5 and most preferably <2. The polydispersity PD stands for the ratio of weight-average particle diameter Dw to number-average particle diameter Dn, PD = Dw / Dn.

The parameters Dw and Dn or the particle size distribution are determined by means of laser light diffraction and laser light scattering using the (meth) acrylic acid ester polymers with the measuring device LS13320 with the optical model PVAC.RF780D, including PIDS, from Beckmann-Coulter and taking into account the instructions of the device manufacturer after sufficient dilution of the aqueous polymer dispersions with deionized water. The selection of monomers or the selection of the proportions by weight of the comonomers is carried out in such a way that, for the (meth) acrylic acid ester polymers, generally glass transition temperatures Tg of <+ 120 ° C, preferably -50 ° C to + 60 ° C, even more preferably - 30 ° C to + 40 ° C and most preferably -15 ° C to + 20 ° C result.

The glass transition temperature Tg can be determined in a known manner by means of differential scanning calorimetry (DSC). The Tg can also be calculated approximately in advance using the Fox equation. According to Fox T. G., Bull. Am. Physics Soc. 1, 3, page 123 (1956) the following applies: 1 / Tg = xl / Tgl + x2 / Tg2 + ... + xn / Tgn, where xn stands for the mass fraction (% by weight / 100) of the monomer n, and Tgn is the glass transition temperature in Kelvin of the homopolymer of the monomer n. Tg values for homopolymers are listed in Polymer Handbook 2nd Edition, J. Wiley & Sons, New York (1975).

The polyvinyl alcohols can be, for example, partially saponified or fully saponified polyvinyl alcohols, preferably with a degree of hydrolysis of 80 to 100 mol%, particularly preferably partially saponified polyvinyl alcohols with a degree of hydrolysis of 80 to 95 mol%, in particular 86 to 90 Mol%. The Höppler viscosity of the polyvinyl alcohols, in 4% aqueous solution, is preferably 1 to 30 mPas, and particularly preferably 2 to 20 mPas and most preferably 3 to 15 mPas (Höppler method at 20 ° C., DIN 53015).

Polyvinyl alcohols are contained in an amount of preferably 1 to 30% by weight, particularly preferably 3 to 20% by weight and most preferably 5 to 15% by weight, based on the total weight of the (meth) acrylic acid ester polymers.

Partially saponified, hydrophobically modified polyvinyl alcohols, in particular partly saponified, hydrophobically modified polyvinyl alcohols with a degree of hydrolysis of 80 to 95 mol%, in particular with a 4% Höppler viscosity, are also preferred aqueous solution from 1 to 30 mPas. Examples of these are partially saponified copolymers of vinyl acetate with hydrophobic comonomers such as isopropenyl acetate, vinyl pivalate, vinyl ethyl hexanoate, vinyl esters of saturated alpha-branched monocarboxylic acids with 5 or 9 to 11 carbon atoms, dialkyl maleate and dialkyl fumarates such as diisopropyl maleate, such as vinyl chloride, vinyl fumarate and diisopropyl fumarate , Olefins such as ethene and decene. The proportion of the hydrophobic units is preferably 0.1 to 10% by weight, based on the total weight of the partially saponified polyvinyl alcohol. Mixtures of the polyvinyl alcohols mentioned can also be used. It is particularly preferred not to contain any hydrophobically modified polyvinyl alcohols.

The polyvinyl alcohols preferably contain no mercapto groups and / or no 1,2-glycol groups. The polyvinyl alcohols consist of preferably> 80% by weight, more preferably> 90% by weight and particularly preferably> 95% by weight of vinyl alcohol and vinyl acetate units, based on the total weight of the polyvinyl alcohols. Most preferably, the polyvinyl alcohols consist exclusively of vinyl alcohol and vinyl acetate units.

Furthermore, in addition to polyvinyl alcohol, one or more further protective colloids can be contained, such as, for example, polyvinyl acetals; Polyvinyl pyrrolidones; Polysaccharides in water-soluble form such as starches (amylose and amylopectin), cellulosene and their carboxymethyl, methyl, hydroxyethyl, hydroxypropyl derivatives, dextrins and cyclodextrins; Proteins such as casein or caseinate, soy protein, gelatin; Lignosulfonates; synthetic polymers such as poly (meth) acrylic acid, copolymers of (meth) acrylates with carboxyl-functional comonomer units, poly (meth) acrylamide, polyvinyl sulfonic acids and their water-soluble copolymers; Melamine formaldehyde sulfonates, naphthalene formaldehyde sulfonates, styrene maleic acid and vinyl ether maleic acid copolymers. The further protective colloids can be contained, for example, in an amount of 0 to 20% by weight, in particular 0.1 to 10% by weight. Further protective colloids are preferably contained in an amount of <20% by weight, particularly preferably <10% by weight. The data in% by weight relate to the total weight of the (meth) acrylic acid ester polymers. Most preferably, no further protective colloids are included. Preferably, only polyvinyl alcohols are contained as protective colloids.

The polyvinyl alcohols and protective colloids mentioned are accessible or commercially available by means of processes known to the person skilled in the art.

Optionally, one or more emulsifiers can also be contained, such as anionic, cationic or nonionic emulsifiers, in particular anionic surfactants, such as alkyl sulfates with a chain length of 8 to 18 carbon atoms, alkyl or alkyl ether sulfates with 8 to 18 carbon atoms hydrophobic radical and up to 40 ethylene or propylene oxide units, alkyl or alkylarylsulfonates with 8 to 18 carbon atoms, esters and half esters of sulfosuccinic acid with monohydric alcohols or alkylphenols, or nonionic surfactants such as alkyl polyglycol ethers or alkylaryl polyglycol ethers with 8 to 40 ethylene oxide Units.

Emulsifiers can be present in an amount of, for example, 0 to 10% by weight, in particular 0.1 to 5% by weight, based on the total weight of the (meth) acrylic acid ester polymers. It is particularly preferred not to contain any emulsifiers.

Another object of the invention are processes for the Her position of polyvinyl alcohol-stabilized (meth) acrylic acid ester polymers with particle sizes Dw from 100 to 900 nm in the form of aqueous dispersions or water-redispersible powders by means of free-radically initiated emulsion polymerization of ethylenically unsaturated monomers in the presence of polyvinyl alcohol in aqueous medium and optionally subsequent drying, characterized in that a) 1 to 30% by weight of one or more vinyl esters of carboxylic acids having 5 to 15 carbon atoms, b) 20 to 80% by weight of one or more (meth) acrylic acid esters whose homopolymer has a glass transition temperature Tg of <20 ° C, c) 10 to 70% by weight of one or more (meth) acrylic acid esters, the homopolymer of which has a glass transition temperature Tg of> 50 ° C, and optionally one or more further ethylenically unsaturated monomers are polymerized, the data in% by weight being based on the total weight of the (Me th) acrylic acid ester polymers.

The polymerization temperature is generally from 40 ° C to 150 ° C, preferably from 60 ° C to 90 ° C.

The polymerization can be initiated using the redox initiator combinations customary for emulsion polymerization. Examples of suitable oxidation initiators are the sodium, potassium and ammonium salts of peroxodisulfuric acid, hydrogen peroxide, t-butyl peroxide, t-butyl hydroperoxide, potassium peroxodiphosphate, t-butyl peroxopivalate, cumene hydroperoxide, isopropylbenzene monohydroperoxide, azobilisisobutyronitrile. The sodium, potassium and ammonium salts of peroxodisulfuric acid and hydrogen peroxide are preferred. The initiators mentioned are generally used in an amount of from 0.01 to 2.0% by weight, based on the total weight of the ethylenically unsaturated monomers.

Suitable reducing agents are, for example, the sulfites and bisulfites of the alkali metals and of ammonium, such as sodium sulfate, the derivatives of sulfoxylic acid such as zinc or alkali formaldehyde sulfoxylates, for example sodium hydroxymethanesulfinate (Bruggolite) and (iso-) ascorbic acid. Sodium hydroxymethanesulfinate and (iso-) ascorbic acid are preferred. The amount of reducing agent is preferably 0.015 to 3% by weight, based on the total weight of the ethylenically unsaturated monomers. The oxidizing agents mentioned, in particular the salts of peroxodisulfuric acid, can also be used on their own as thermal initiators.

To control the molecular weight, regulating substances can be used during the polymerization. If regulators are used, they are usually used in amounts between 0.01 to 5.0% by weight, based on the monomers to be polymerized, and are dosed separately or premixed with reaction components. Examples of such substances are n-dodecyl mercaptan, tert-dodecyl mercaptan, mercaptopropionic acid, methyl mercaptopropionate, isopropanol and acetaldehyde. Preferably no regulating substances are used.

To stabilize the polymerization batch, polyvinyl alcohol is used in the emulsion polymerization in an amount of preferably a total of 1 to 20% by weight, based on the total weight of the ethylenically unsaturated monomers.

In the case of emulsion polymerization, batch processes can be used, with all components of the Polymerisationsansat zes being presented in the reactor, or semi-batch processes, where individual or more components are presented and the remainder is metered in, or a continuous Polymerisa tion are carried out, the Components are metered in during the polymerization. If necessary, the dosages can be carried out separately (in terms of space and time).

Vinyl ester a) is preferably partially or in particular completely initially introduced. The (meth) acrylic acid esters b) and / or the (meth) acrylic acid esters c) and, if appropriate, the further monomers are preferably wholly or partially metered in. The total amount of vinyl ester a) used is particularly preferably initially introduced or metered in before the (meth) acrylic acid ester b) and / or the (meth) acrylic acid ester c) and, if appropriate, the further monomers are metered in. Most preferably the vinyl esters a) are given partially or in particular completely polymerized before the (meth) acrylic acid esters b) and / or the (meth) acrylic acid esters c) and optionally the further monomers are metered in. All the monomers are preferably polymerized in the same reactor. Alternatively, it is also possible to use a polymer based on the vinyl ester a) in the form of an aqueous dispersion as a seed and to use the (meth) acrylic acid ester b), the (meth) acrylic acid ester c) and optionally the other monomers in the presence of the seed to polymerize. Some or all of the seed can be presented or partially or fully metered in. The seed is preferably presented in full.

After the emulsion polymerization has ended, post-polymerization can be carried out using known methods to remove residual monomers, for example by post-polymerization initiated with a redox catalyst. Volatile residual monomers can also be removed by means of distillation, preferably under reduced pressure, and if necessary by passing through or passing over inert entrainment gases such as air, nitrogen or steam.

The (meth) acrylic acid ester polymers are generally obtained in the form of polyvinyl alcohol-stabilized aqueous dispersions. The aqueous dispersions have a solids content of preferably 30 to 75% by weight and particularly preferably 40 to 65% by weight.

To prepare the (meth) acrylic ester polymers in the form of water-redispersible powders, the aqueous dispersions, optionally after the addition of protective colloids, for example polyvinyl alcohol, in particular the polyvinyl alcohol described above, can be dried as a drying aid, for example by means of fluidized bed drying, freeze drying or spray drying . The dispersions are preferably spray-dried. The spray drying can be carried out in conventional spray drying systems, the atomization being able to take place, for example, by means of single-, dual- or multi-fluid nozzles or with a rotating disk. The outlet temperature is generally in the range of 45 ° C to 120 ° C, preferably 60 ° C to 90 ° C, depending on the system, Tg of the resin and ge desired degree of dryness selected.

As a rule, the drying aid is used in a total amount of 3 to 30% by weight, based on the polymeric constituents of the dispersion. The total amount of protective colloid, in particular polyvinyl alcohol, before the drying process is preferably 3 to 30% by weight, particularly preferably 5 to 20% by weight, based on the polymer content. Suitable drying aids are, for example, the protective colloids mentioned above, in particular polyvinyl alcohols, preferably the polyvinyl alcohols described above. Preference is given to using no further protective colloids other than polyvinyl alcohol as a drying aid.

When spraying, the addition of antifoam agents has often proven to be beneficial, preferably up to 3 wt .-% antifoam agent, based on the total weight of the (meth) Acrylsäu ester polymers. To increase the shelf life by improving the blocking stability, the powder obtained can be equipped with an antiblocking agent (anticaking agent), preferably up to 30% by weight, based on the total weight of polymeric constituents. Examples of antiblocking agents are calcium carbonate or magnesium carbonate, talc, gypsum, silicic acid, in particular hydrophobic silicic acid, kaolins, silicates with particle sizes, preferably in the range from 10 nm to 10 μm.

The viscosity of the food to be atomized is preferably adjusted via the solids content so that a value of <500 mPas (Brookfield viscosity at 20 revolutions and 23 ° C.), particularly preferably <250 mPas, is obtained. The solids content of the dispersion to be atomized is preferably> 35%, particularly preferably> 40%.

To improve the application properties, further additives can be added, for example during the spraying. Further constituents of redispersible polymer powder compositions contained in preferred embodiments are pigments, fillers, foam stabilizers, Water repellants.

The (meth) acrylic ester polymers stabilized according to the invention polyvinyl alcohol are particularly suitable for use in construction chemical products. They can be used alone or in combination with conventional polymer dispersions or dispersion powders, optionally in conjunction with hydraulically setting binders such as cements (Portland, aluminate, trass, metallurgical, magnesia, phosphate cement), gypsum and water glass for the production of Leveling compounds, construction adhesives, plasters, leveling compounds, grouts, sealing slurries, thermal insulation composite systems or paints such as powder paints. Under construction adhesives, tile adhesives or full heat protection adhesives are preferred areas of application for dispersion powder compositions. Preferred areas of application for the dispersion powder compositions are leveling compounds, and particularly preferred leveling compounds are self-leveling floor leveling compounds and screeds.

Surprisingly, according to the invention, finely divided, polyvinyl alcohol-stabilized (meth) acrylic acid ester polymers are available which are storage-stable in the form of aqueous dispersions, redispersible powders or corresponding aqueous redispersions. Conventional, unmodified polyvinyl alcohols can advantageously be used for this purpose, so that this does not interfere with the property profile of application products. The (meth) acrylic acid ester polymers can be produced by established processes. All of this is also economically advantageous.

In addition, the (meth) acrylic acid ester polymers according to the invention lead in applications to advantageous mechanical properties, such as, for example, adhesive tensile strength, and in paint applications to high covering power, color density and, in particular, high wet abrasion resistance.

The following examples serve to further explain the invention: Production of the polymer dispersions:

Example 1 (Ex. 1):

The following components were placed in a polymerization reactor with a volume of 3 liters:

330 g water, 132 g of a 20% by weight aqueous solution of a partially saponified polyvinyl alcohol (degree of hydrolysis: 88 mol%; Höppler viscosity of 4 mPas (determined according to Höppler according to DIN 53015, 20 ° C, 4% aqueous solution) and 0.6 g of a 1% aqueous iron ammonium sulfate solution.

The reactor was provided with a nitrogen protective gas atmosphere. 197 g of vinyl laurate were added and the mixture was heated to 70.degree.

The polymerization was carried out by adding 5% by weight aqueous tert-butyl hydroperoxide solution (TBHP) at a rate of 12 g / h and adding 5% by weight aqueous ascorbic acid solution at a rate of 12 g / h started.

After 10 min, the monomer metering consisting of 592 g of butyl acrylate and 527 g of methyl methacrylate was started at a rate of 280 g / h (duration 4 h). At the same time, an aqueous dosage consisting of 557 g of water and 559 g of a 20% by weight solution of a partially saponified polyvinyl alcohol (degree of hydrolysis: 88 mol%; Höppler viscosity: 4 mPas) was started at a rate of 280 g / h ( Duration 4 h). After the monomer had been metered in, the polymerization was continued for a further 1 hour.

After the dispersion had cooled, polymerization was carried out with the addition of 6.5 g of a 5% strength by weight aqueous TBHP solution and 6.5 g of a 5% strength by weight aqueous ascorbic acid solution.

The properties of the polymer dispersion obtained in this way are summarized in Table 1. The properties were determined as stated above in the general description.

Examples 2 to 6 and Comparative Example 7 (Ex. 2-6, Ex. 7): The polymer dispersions of Ex. 2-6 and Ex. 7 were prepared as described for Example 1, with the difference that the polymer dispersions of Ex. 2-6 and Ex specified monomers were used.

The properties of the polymer dispersions obtained in this way are summarized in Table 1. The properties were determined as stated above in the general description or can be carried out in a conventional manner.

Table 1: Properties of the polymer dispersions from Examples 1 to 6 and Comparative Example 7:

*: Brookfield viscosity: determined at 20 revolutions and 23 ° C.

Table 2: Monomer composition of the polymers from Example 1 to 6 and Comparative Example 7: Preparation of the dispersion powder compositions PI to P6 and VP7:

The polymer dispersions from (comparative) Examples 1 to 7 were each with the addition of 2.0% by weight, based on the polymer content of the dispersion (solid / solid), of a partially saponified polyvinyl alcohol (degree of hydrolysis: 88 mol%; Höppler viscosity : 4 mPas in 4% aqueous solution)) and 6.0% by weight, based on the polymer content of the dispersion (solid / solid), of a partially saponified polyvinyl alcohol (degree of hydrolysis: 88 mol%; Höppler viscosity: 13 mPas in 4 % strength aqueous solution) dried by spray drying in a conventional manner at an inlet temperature of 130 ° C. and an outlet temperature of 80 ° C., as a result of which redispersible powders were obtained. The powders were stabilized as anti-caking agents by adding 4% by weight of kaolin and 16% by weight of calcium carbonate.

In all (comparative) examples 1 to 7, free-flowing, stable dispersion powders were obtained.

Determination of the properties of the dispersion powder compositions PI to P6 and VP7:

Determination of the blocking resistance (BF):

To determine the blocking resistance, the powder to be examined was filled into an iron pipe with a screw connection and then loaded with a metal stamp. It was stored under load in the drying cabinet at 50 ° C. for 16 hours. After cooling to room temperature, the powder was removed from the tube and the blocking stability was determined qualitatively by crushing the powder. The results of the testing are listed in Table 3.

The block stability was classified as follows:

1 = very good block stability

2 = good block stability

3 = satisfactory block stability

4 = not block-stable, powder no longer after crushing pourable.

Determination of the sitting behavior (RA):

The settling behavior of redispersions serves as a measure of the redispersibility of redispersible powders. The powder to be investigated was redispersed in a concentration of 50% by weight in water by the action of strong shear forces.

The settling behavior was then determined on dilute redispersions (0.5% solids content), and for this purpose 100 ml of this dispersion was placed in a graduated tube, and the settling height of solids was measured. The information is given in mm settling after 1 hour and 24 hours. Values greater than 7 indicate very inadequate redispersion of the powder. The results of the testing are listed in Table 3.

Table 3: Dispersion powder compositions of Examples 1 to 6 and Comparative Example 7:

Application testing of the dispersion powder compositions:

Tile glue :

The dispersion powder compositions were examined for their suitability for bonding ceramic tiles. Dry mortar of the following composition was produced: 420 parts Milke Premium cement CEM I 52.5R,

446 parts of quartz sand,

80 parts calcium carbonate,

4 parts Tylose MB60000 (thickener),

10 parts calcium formate (accelerator),

40 parts of dispersion powder composition as given in Table 4.

The tile adhesive mortar was mixed with 34 g of water per 100 g of dry mortar.

The tiles were laid with the tile adhesive in the conventional way.

The test according to DIN EN 12004 (test standard EN 1348) resulted in the test results listed in Table 4.

Table 4: Test results of the tile adhesive:

The tile adhesives with the dispersion powder compositions PI to P6 according to the invention showed, compared to the tile adhesive with the comparative dispersion powder composition VP7, improved tensile strengths, in particular improved wet strengths, freeze-thaw resistance (FT) and also after exposure to heat.

Sealing slurry:

The dispersion powder compositions P3 and P4 as well as VP7 were also tested in flexible sealing slurries with regard to adhesive tensile strength.

The sealing slurries were based on the recipe in Table 5 and were made and applied in a conventional manner. The testing of the adhesive tensile strength of the sealing slurry after storage in a standard climate or after storage in water was carried out in accordance with EN 14891.

Table 5: Recipe of the sealing slurry: Table 6: Adhesive tensile strengths of the sealing slurry:

The adhesive tensile strength of sealing slurries can be improved by using dispersion powder compositions according to the invention.

Dispersion dyeing:

The dispersion powder compositions were examined for their suitability for use in dispersion paints. The dispersion paints were based on the recipe in Table 7 and were prepared and tested in a conventional manner as in Described below. The test results are summarized in Table 8.

Table 7: Formulation of the emulsion paints:

Test methods:

Testing the Scrub Resistance SF (Wet Abrasion Resistance) of the Dispersion Dyes: To determine the wet abrasion resistance, the emulsion paints produced from the powder paints were each tested using the fleece method in accordance with ISO 11998.

The emulsion paint was applied in each case with an applicator in a layer thickness of 300 gm (wet) to a Leneta film (PVC film).

This was followed by storage for 72 hours in a standard climate (DIN 50014, 23 ° C. and 50% relative humidity), then for 24 hours at 50 ° C. and finally for 24 hours in a standard climate.

The result was a dry layer thickness of approx. 200 gm. Then three test strips with the dimensions 2.5 cm × 7.5 cm were cut out and then weighed. The abrasion test was carried out with 200 cycles and then weighed again. The paint removal in gm was then calculated from the paint density of the scoured surface and the loss of mass of the paint film.

A mean value from three measurements was determined in each case. The abrasion resistance after 200 cycles is assessed in classes: Class 1 with abrasion less than 5 gm,

Class 2 with abrasion between 5 pm and less than 20 pm,

Class 3 with abrasion between 20 pm and less than 70 pm.

Measurement of the Brookfield viscosities BF100 of the disperse paints:

The Brookfield viscosity of the emulsion paints produced with the powder paint compositions was measured with a Brookfield viscometer BF 35, after heating to 23 ° C., using the spindle specified in the operating instructions at 100 revolutions per minute (BF100).

The viscosity is given in mPas.

Determination of the opacity of the emulsion paints:

The opacity was determined using the DIN EN 13300 method described in the "Guideline for determining the opacity" of the Association of the German Paint Industry, July 2002 edition.

The emulsion paints were kator with an automatic film applicator, with a doctor blade with a gap height of 150 pm and 225 pm, each on black and white contrast cards (type 3H from Lenetta) with standard color value Y over black of 7 or less and standard color value Y over white of 80 to 90 applied.

The contrast cards coated in this way were dried for 24 hours at 23 ° C. and 50% relative humidity and then weighed.

^{The coverage in m 2} / l was calculated from the amount applied in g / m ² and the color density. Using a colorimeter (Elrepho 450X from Datacolor), the standard color values Y (color standards) were measured over the black and white bases and the “contrast ratio” in “%” was calculated. The values determined in this way for the contrast ratio were plotted in a diagram against the corresponding yield (m ² / l). The yield E at 7m ² / l with a contrast ratio of 98% was determined by interpolation.

The higher the yield E, the better the opacity.

Table 8: Test results of the emulsion paints:

With the powders according to the invention, the wet abrasion resistance of emulsion paints could be increased considerably. The other properties correspond to the requirements for dispersion paints.

Claims

Patent claims:

1. Polyvinyl alcohol-stabilized (meth) acrylic acid ester polymers with particle sizes Dw of 100 to 900 nm in the form of aqueous dispersions or water-redispersible powders, characterized in that the (meth) acrylic acid ester polymers are based on a) 1 to 30% by weight one or more vinyl esters of carboxylic acids with 5 to 15 carbon atoms, b) 20 to 80% by weight of one or more (meth) acrylic acid esters, the homopolymer of which has a glass transition temperature Tg of <20 ° C., c) 10 up to 70% by weight of one or more (meth) acrylic acid esters, the homopolymer of which has a glass transition temperature Tg of> 50 ° C., and optionally one or more further ethylenically unsaturated monomers, the data being in% by weight based on the total weight of the (meth) acrylic acid ester polymers.

2. Polyvinyl alcohol-stabilized (meth) acrylic acid ester polymers according to claim 1, characterized in that one or more (meth) acrylic acid esters b) are selected from the group comprising n-butyl acrylate, n-hexyl acrylate, n-hexyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate and stearyl acrylate.

3. Polyvinyl alcohol-stabilized (meth) acrylic acid ester polymers according to claim 1 or 2, characterized in that one or more (meth) acrylic acid esters c) are selected from the group comprising methyl methacrylate, tert-butyl methacrylate and tert-butyl acrylate.

4. Polyvinyl alcohol-stabilized (meth) acrylic acid ester polymers according to claims 1 to 3, characterized in that the (meth) acrylic acid ester polymers are 50 to 99% by weight based on (meth) acrylic acid esters b) and (meth) acrylic acid esters c) based on the total weight of the (meth) Acrylsäu ester polymers.

5. Polyvinyl alcohol-stabilized (meth) acrylic acid ester polymers according to claim 1 to 4, characterized in that the (meth) acrylic acid ester polymers are additionally based on one or more ethylenically unsaturated silanes d) of the general formula R ¹ SiR ² ₀₂ (OR ³ ) ₁₃ , wherein R ^{2 is} a Ci- to C ₃ -alkyl radical, Ci- to C3-alkoxy radical or halogen, R is CH ₂ = CR ⁴ - (CH ₂ ) _0-1 or CH ₂ = CR ⁴ C0 ₂ (CH ₂ ) has ₁₃ with R ⁴ as Koh lenstoffrest with 1 to 10 carbon atoms, R ^{3 is} an unbranched or branched, optionally substituted alkyl radical with 1 to 12 carbon atoms.

6. Polyvinyl alcohol-stabilized (meth) acrylic acid ester polymers according to claims 1 to 5, characterized in that the (meth) acrylic acid ester polymers are additionally based on glycidyl methacrylate or glycidyl acrylate.

7. Polyvinyl alcohol-stabilized (meth) acrylic acid ester polymers according to claim 1 to 6, characterized in that the (meth) acrylic acid ester polymers to 0 to 20 wt .-%, based on the total weight of the (meth) acrylic acid ester polymers, on one or more ethylenically unsaturated monomers f ) are selected from the group comprising vinyl esters of carboxylic acids with 2 to 4 carbon atoms, olefins, dienes, vinyl aromatics and vinyl halides.

8. polyvinyl alcohol-stabilized (meth) acrylic acid ester polymers according to claim 1 to 7, characterized in that the (meth) acrylic acid ester polymers no ethylene unit and / or no unit of a vinyl ester of a carboxylic acid with 2 to

Contains 4 carbon atoms.

9. Polyvinyl alcohol-stabilized (meth) acrylic acid ester polymers according to claim 1 to 8, characterized in that the polyvinyl alcohols consist exclusively of vinyl alcohol and vinyl acetate units.

10. Polyvinyl alcohol-stabilized (meth) Acrylic acid ester polymers according to Claims 1 to 9, characterized in that they contain no emulsifiers.

11. Polyvinyl alcohol-stabilized (meth) acrylic acid ester polymers according to claims 1 to 10, characterized in that the (meth) acrylic acid ester polymers have a polydispersity PD of <3.

12. A process for the preparation of polyvinyl alcohol stabilized (meth) acrylic acid ester polymers with particle sizes Dw from 100 to 900 nm in the form of aqueous dispersions or water-redispersible powders according to claims 1 to 10 by means of free-radically initiated emulsion polymerization of ethylenically unsaturated monomers in the presence of polyvinyl alcohol in aqueous medium and optionally subsequent drying, characterized in that a) 1 to 30% by weight of one or more vinyl esters of carboxylic acids with 5 to 15 carbon atoms, b) 20 to 80% by weight of one or more ( Meth) acrylic acid esters whose homopolymer has a glass transition temperature Tg of <20 ° C, c) 10 to 70% by weight of one or more (meth) acrylic acid esters whose homopolymer has a glass transition temperature Tg of> 50 ° C have, and optionally one or more other ethylenically unsaturated monomers are polymerized, the information in wt .-% based on the total weight of the (meth) acrylic acid ester polymers.

13. A process for the preparation of polyvinyl alcohol stabilized (meth) acrylic acid ester polymers according to claim 12, characterized in that the vinyl esters a) are partially or completely initially charged and the (meth) acrylic acid esters b) and / or the (meth) acrylic acid esters c) and if appropriate, all or some of the other ethylenically unsaturated monomers are metered in.

14. Use of the polyvinyl alcohol-stabilized (meth) acrylic acid ester polymers from claims 1 to 11 in leveling compounds, plasters, fillers, grouts, tile adhesives, full thermal protection adhesives, sealing slurries, thermal insulation composite systems or paints.