EP3625187A1

EP3625187A1 - Dispersion powder composition containing vinyl alcohol copolymerisate

Info

Publication number: EP3625187A1
Application number: EP17748688.3A
Authority: EP
Inventors: Abdulmajid Hashemzadeh; Peter BRANDMÜLLER; Walter Dobler; Hardy Herold
Original assignee: Wacker Chemie AG
Current assignee: Wacker Chemie AG
Priority date: 2017-07-24
Filing date: 2017-07-24
Publication date: 2020-03-25
Also published as: US11339228B2; WO2019020157A1; US20210122839A1

Abstract

The invention relates to polymer powder compositions which can be redispersed in water and which contain a vinyl alcohol copolymerisate. The compositions are obtained in that one or more ethylenically unsaturated monomers are radically polymerized in the presence of protective colloids and/or emulsifiers in an aqueous medium, and the aqueous polymer dispersion obtained in this manner is dried by adding a protective colloid as a drying aid. The invention is characterized in that during the polymerization and/or drying process, one or more vinyl alcohol copolymerisates are used as protective colloids containing a) 80 to 99 mol.% of vinyl alcohol monomer units, b) 0.5 to 10 mol.% of monomer units which are derived from vinyl esters of unbranched or branched alkyl carboxylic acids with 3 to 18 C atoms, c) 0.5 to 10 mol.% of monomer units which are derived from ethylenically unsaturated monomers with one or more functional groups selected from the group comprising a carboxylic acid group, a sulfonic acid group, a quaternized amine group, a phosphoric acid group, and the salts thereof, and d) 0 to 5 mol.% of vinyl acetate monomer units, wherein the specifications in mol.% add up to 100 mol.% in each case.

Description

Dispersion powder composition containing vinyl alcohol copolymer

The invention relates to a dispersion powder composition comprising vinyl alcohol copolymer, process for their preparation ^¬ and their use.

Water-redispersible polymer powders (polymer powders) are polymer powders which are generally obtained by drying the corresponding aqueous polymer dispersions of the film-forming base polymer in the presence of a drying aid (generally a protective colloid). On account of the protective colloid content, on the one hand during the drying process the polymer particles are prevented from irreversibly sticking because the polymer particles are enveloped by the water-soluble protective colloid particles. On the other hand, this protective colloid matrix, which dissolves again when the polymer powder is dispersed in water, causes the polymer particles to again be present with the particle size of the starting dispersion in the aqueous redispersion (TIZ Fachberichte, 1985, Vol. 109 (9), 698 ).

As protective colloids usually polyvinyl alcohols are ^¬ sets, for example, in the method described in WO

2013/017491 AI is described. EP 1020493 A1 describes the use of a partially acetalized, water-soluble polyvinyl alcohol as a drying aid in the preparation of a water-redispersible polymer powder by spray-drying the corresponding polymer dispersion. In the WO

2012/159848 AI are fully hydrolysed vinyl acetate copolymers isopropenyl acetate as a protective colloid for stabilizing egg ^¬ ner aqueous polymer dispersion and as a drying aid for the drying of an aqueous polymer dispersion. EP 477900 A2 describes dispersion powder compositions with polyvinyl alcohol which improve the properties of so that modified building materials still contain fully hydrolyzed vinyl acetate 1-methylvinyl acetate copolymers. EP 1400557 Al describes the use of a vinyl alcohol copolymer with 1 to 12 mol% of ethylene units as a drying aid in the production of dispersion powders. In EP 1420033 Bl partially hydrolyzed vinyl acetate-ethylene copolymers are used as Schutzkol ^¬ loid in the preparation of a copolymer dispersion and as a drying aid in the spray drying of aqueous polymer dispersions.

Such dispersion powders are mainly used in construction chemical products, for example in dry mortar formulations, which are made ready for use by adding water. In addition to dispersion powder, these dry mortar formulations also contain mineral binders such as cement, as well as fillers and optionally other additives. Such Tro ^¬ ckenmörtelformulierungen be mixed with water, and the thus obtained mortar, for example as tile adhesives, joint ^¬ filler, putty, plasters, screed or plied ap- as Dichtschlämme.

It is important that this fresh mortar have good Verarbeitungsei ^¬ properties, and the mortars thus obtained cured high mechanical strength and a strong liability on different substrates have.

In the case of one-component sealing slurries, in addition to the water-tightness in the cured state, low tackiness and high stability during processing of the fresh mortar, especially in the case of thicker layers, are decisive. In order to optimize the water-tightness, therefore, relatively high amounts of dispersion powder (up to 50% by weight, based on the total weight of the dispersion) are used in dry mortar formulations for sealing slurries Dry mortar formulation) incorporated. Because of the protective colloids contained in the dispersion powders, which are used in their preparation by drying the corresponding aqueous polymer dispersions as drying aids, the viscosity and the tackiness of the mortar compositions is increased, especially at high levels of dispersion powder in dry mortars.

Sealing slurries can be applied, for example, with a brush or roller. This requires a low viscosity, since ^¬ can be applied easily with the sludge. Therefore, in this method of application more water is used in the formulation, which although the tackiness decreases very much, but a considerably higher time required, since many layers must be applied, to the prescribed in the standards, for example in DIN EN 14891, minimum dry - Layer thickness of 2 mm is obtained. In practice, therefore, more and more the order of the sludge by means of toothed spatula prevails. In order to prevent the running of the applied masses, one needs a special flow behavior, ie a good stability. Although increasing the viscosity of the mortar ^¬ telmasse, the stability of the mortar improves, but it also increases the stickiness. It is an object of the present invention to provide a dispersion powder composition which, when used for the production of mortar compositions, improves the stability even at relatively large added amounts without excessively increasing the tackiness of the mortar.

The invention (in water redispersible poly ^¬ merpulver compositions dispersion powder Zusammensetzun- gen) containing vinyl alcohol copolymer, which are characterized keep it ^¬ that one or more ethylenically unsaturated monomers in the presence of a protective colloid and / or emulsifier are polymerized in an aqueous medium radical, and the DA in resulting aqueous polymer dispersion after the addition of

Protective colloid is dried as a drying aid, characterized ge ^¬ indicates that

in the polymerization and / or drying as a protective colloid, one or more vinyl alcohol copolymers containing a) from 80 to 99 mol% of vinyl alcohol monomer units, b) from 0.5 to 10 mol% of monomer units derived from vinyl esters of unbranched or branched alkylcarboxylic acids with 3 to 18 carbon atoms, c) 0.5 to 10 mol% of monomer units which are quaternized by ethylenically unsaturated monomers having one or more functional groups selected from the group comprising Car ^¬ bonsäure radical, sulfonic acid radical Amine radical, phosphoric acid radical, and salts thereof, and d) 0 to 5 mol% vinyl acetate monomer units, wherein the data in mol% in each case add up to 100 mol% can be used.

The vinyl alcohol copolymers comprise a) 80 to 99 mol%, preferably 85 to 97 mol% vinyl alcohol monomer units, b) 0.5 to 10 mol%, preferably 1 to 8 mol%, Monomereinhei ^¬ th which derived from vinyl esters of unbranched or branched alkylcarboxylic acids having 3 to 18 carbon atoms, c) 0.5 to 10 mol%, preferably 1 to 8 mol%, ^{Monomereinhei} th, which of ethylenically unsaturated monomers with a or more functional groups selected from the group consisting of carboxylic acid residue, sulfonic acid residue, quaternized lized amine radical, phosphoric acid radical, as well as their salts are derived, from ^¬, and

d) 0 to 5 mol%, preferably 1 to 4 mol%, vinyl acetate-mono ^¬ mer units, where the data in mol% respectively per 100 mol% aufaddie ^¬ ren.

Preferred vinyl esters of unbranched or branched alkylcarboxylic acids having 3 to 18 carbon atoms are vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl laurate, 1-methylvinyl acetate and vinyl esters of α-branched monocarboxylic acids having 5 to 13 C atoms. Atoms, for example vinyl pivalate, VeoVa9 ^R , VeoVal0 ^R or VeoVall ^R (trade name of Hexion). Particularly preferred are the vinyl esters of α-branched monocarboxylic acids having 9 to 10 C atoms (VeoVa9 ^R and VeoVal0 ^R ).

As monomers c) suitable ethylenically unsaturated carboxylic acids are, for example, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid and its anhydride, monoesters of fumaric acid or maleic acid, such as the ethyl and isopropyl esters, or unsaturated fatty acids having 7 to 25 carbon atoms, and the salts of the carboxylic acids mentioned. Acrylic and methacrylic acid, maleic acid (anhyd- chloride) and crotonic acid, and the salts of said Carbonsäu ^¬ ren are preferred.

Monomers c) suitable monomers with sulfonic acid group are vinylsulfonic acid, styrenesulfonic acid, allylsulfonic acid, methallylsulfonic acid, p-Methallyloxyphenylsulfonsäure, and sulfonic acids of the general formula CH ₂ = CR ¹ -CO-X-CR ² R ³ -R ⁴ - S0 ₃ H, where X = 0 or NH, and R ¹ , R ² , R ^{3 are} identical or different and are H and Ci- to C3-alkyl, and R ^{4 is} Ci- to C4-alkylene, and the Salts of the acids mentioned. Preference is given to vinylsulfonic acid, sulfopropyl (meth) acrylate, 2-acrylamido-2-methylpropanesulfonic acid and methallylsulfonic acid, 1-allyloxy-2-hydro- roxy sulfonic acid, acrylic acid (3-sulfopropyl) ester, methacrylic acid (3-sulfopropyl) ester, itaconic acid bis (3-sulfopropyl) ester, and the salts of said acids. Quaternized amine monomers suitable as monomers c) are diallyldimethylammonium chloride (DADMAC), diallyl diethylammonium chloride (DADEAC), (3-methacryloxy) propyltrimethylammonium chloride (MPTAC), (3-methacryloxy) ethyltrimethylammonium chloride (METAC), (3 Methacrylamido) propyl trimethyl ammonium chloride (MAPTAC).

Suitable monomers with phosphoric acid radical are vinylphosphonic acid and dimethyl vinylphosphonate, phosphoalkyl methacrylates, such as phosphoethyl methacrylate and phosphopropyl methacrylate.

The most preferred monomers c) are vinylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and salts thereof. Optionally, up to 5 mol% of reactive monomers from the group of ethylenically unsaturated monomers with alkoxysilane group or epoxy group or amine group or amide group can be copolymerized. Preference is given to vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, vinyltriacetoxysilane, 3-methacryloxypropyltrimethoxysilane, glycidyl methacrylate, diacetoneacrylamide, N-vinylformamide and vinylamine.

The vinyl alcohol copolymers can be mentioned comonomers and subsequent hydrolysis of the thus obtained vinyl acetate copolymers are prepared with ^¬ means of radical polymerization of vinyl acetate with the under b) and c) in a known manner. Preferably by bulk polymerization, emulsion po- lymerisation, suspension polymerization or particularly preferably by polymerization in organic solvents, most preferably in alcoholic solution with monohydric, aliphatic alcohols having 1 to 4 carbon atoms or their Gemi see as a solvent. Suitable solvents are in ^¬ play, methanol, ethanol, propanol, isopropanol, and an ethanol-isopropanol mixture. The polymerization is carried out under reflux at a temperature of 35 ° C to 100 ° C. The radical initiation takes place by adding common initiators. Examples of customary initiators are percarbonates, such as cyclohexyl peroxydicarbonate, peresters, such as t-butyl perodecanoate or t-butyl peroxypivalate, peroxide initiators, such as t-butyl hydroperoxide, diacyl peroxides, such as dilauroyl peroxide, and azo initiators, such as azobisisobutyronitrile (AIBN), 2,2'-azobis. (4-methoxy-2,4-dimethylvaleronitrile). The monomers can be initially charged in total, added in total, or be ^{charged in portions} , and the remainder added after the initiation of the polymerization. The initiator is preferably initially introduced and the remaining portion is metered in each case. The molecular weight adjustment may be in the

Known manner by polymerization in the presence of molecular weight regulators done.

The saponification (transesterification, hydrolysis) of vinyl acetate copoly merisats carried out in manner known per se, for example by the kneader or in a stirred tank, preferably in the alkali ^¬ rule with the addition of base. The vinyl acetate copolymer is preferably in an alcoholic solution with monohydric, aliphatic alcohols having 1 to 4 carbon atoms or their mixtures as solvent. Metha ^¬ nol and ethanol / isopropanol mixture are particularly preferred. The content of vinyl acetate copolymer in the solution is 20 to 85 wt .-%, preferably 30 to 80 wt .-%. To initiate the hydrolysis It is preferred to use alkaline catalysts. These are, for example, the hydroxides, alkoxides and carbonates of Al ^¬ kali- or alkaline earth metals. Preference is given to sodium hydroxide. The alkaline catalysts are preferably used in alcoholic solution. Most preferred is a methano ^¬ metallic solution of NaOH. The amounts of alkaline catalyst used are generally 0.2 to 20.0 wt .-%, based on the vinyl acetate copolymer. The hydrolysis is generally carried out at temperatures of 40 ° C to 90 ° C, preferably 50 ° C to 85 ° C, generally in a stirred tank. By adding the catalyst solution, saponification is initiated. Upon reaching the desired degree of hydrolysis, the hydrolysis is stopped. Preferably, during the Versei- tion reaction of the ester formed in the transesterification is distilled off. In the preferred alkaline-catalyzed hydrolysis, the termination takes place by addition of acidic reagents, such as carboxylic acids or mineral acids, preferably acetic acid.

After completion of the saponification reaction, the solvent is distilled off, for example by means of steam stripping and the vinyl alcohol copolymer dissolved in water. The vinyl alcohol copolymer can also be separated from the liquid phase by precipitation or drying and isolated as a solid. As a drying aid in the drying of the aqueous polymer dispersion obtained by means of radical polymerization, the vinyl alcohol copolymer is preferably used in aqueous solution.

Vinylester of straight-chain or branched alkyl carboxylic acids are ^¬ men having 1 to 15 C-Ato for the preparation of the aqueous polymer dispersions of the Ba sispolymerisats suitable monomers, methacrylic acid ester and acrylate of alcohols having 1 to 15 C atoms, vinyl aromatics, olefins, dienes or vinyl halides.

Preferred vinyl esters are vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl laurate, 1-methylvinyl acetate, vinyl pivalate and vinyl esters of alpha-branched monocarboxylic acids having 9 to 13 carbon atoms, for example VeoVa9® or VeoValO® ( Trade name of company Momentive). Especially before ^¬ is Trains t vinyl acetate.

Preferred methacrylic esters or acrylic esters are methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, norbornyl acrylate. Particularly preferred are methyl acrylate, methyl methacrylate, n-butyl acrylate and 2-ethylhexyl acrylate.

Examples of olefins and dienes are ethylene, propylene and 1,3-butadiene. Suitable vinyl aromatics are styrene and vinyl toluene. A preferred vinyl halide is vinyl chloride.

Optionally, from 0.05 to 50 wt .-%, preferably 1 to 10 wt .-%, based on the total weight of the monomers, auxiliary monomers can be copolymerized. Examples of Hilfsmono- mers are ethylenically unsaturated mono- and dicarboxylic acids, preferably acrylic acid, methacrylic acid, fumaric acid and maleic acid ^¬; ethylenically unsaturated carboxylic acid amides and nitriles, preferably acrylamide and acrylonitrile; Mono- and diesters of fumaric acid and maleic acid, such as the diethyl and diisopropyl esters, and also maleic anhydride, ethylenically unsaturated sulfonic acids or salts thereof, preferably vinylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid. Further examples are precrosslinking comonomers such as polyethylenically unsaturated comonomers, for example divinyl adipate, diallyl maleate, allyl methacrylate or triallyl cyanurate, or post-crosslinking comonomers, for example acrylamidoglycolic acid (AGA), methyl acrylamidoglycolic acid methyl ester (MAGME), N-methylolacrylamide (NMA), N-methylol methacrylamide (NMMA), N-methylolallyl carbamate, alkyl ethers such as the isobutoxy ether or esters of N-methylolacrylamide, N-methylolmethacrylamide and N-methylolallyl carbamate. Also suitable are epoxide-functional comonomers such as glycidyl methacrylate and glycidyl acrylate. Further examples are silicon-functional comonomers, such as acryloxypropyltri (alkoxy) and methacryloxypropyltri (alkoxy) silanes, such as methacryloxypropyltrimethoxysilane, vinyltrialkoxysilanes and vinylmethyldialkoxysilanes, such as vinyltrimethoxysilane or vinyltriethoxysilane or vinylmethyldimethoxysilane, alkoxy groups containing, for example, methoxy, ethoxy and ethoxypropylene glycol ether radicals could be. Mention may also be made of monomers having hydroxyl or CO groups, for example methacrylic and acrylic hydroxyalkyl esters such as hydroxyethyl, hydroxypropyl or hydroxybutyl acrylate or methacrylate, and also compounds such as diacetone acrylamide and acetylacetoxyethyl acrylate or methacrylate. Further suitable comonomers are vinyl alkyl ethers, such as, for example, vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl octadecyl ether.

Examples of homopolymers and copolymers which are suitable as base polymers are vinyl acetate homopolymers, copolymers of vinyl acetate with ethylene, copolymers of vinyl acetate with ethylene and one or more further vinyl esters,

Copolymers of vinyl acetate with ethylene and acrylic acid ter, copolymers of vinyl acetate with ethylene and vinyl chloride, styrene-acrylic acid ester copolymers, styrene-1, 3-butadiene copolymers.

Preference is given to vinyl acetate homopolymers;

Copolymers of vinyl acetate with from 1 to 40% by weight of ethylene; Copolymers of vinyl acetate with 1 to 40 wt .-% of ethylene and 1 to 50 wt .-% of one or more other Comonome- ren from the group of vinyl esters having 3 to 15 carbon atoms in the carboxylic acid such as vinyl propionate, vinyldodecanoate, vinyl esters of alpha branched carboxylic acids having 9 to 13 C atoms, such as VeoVa9®, VeoValO®, VeoVall®;

Copolymers of vinyl acetate with 1 to 50 wt. ~ 6 of one or more further comonomers from the group of vinyl esters having 3 to 15 carbon atoms in the carboxylic acid radical such as vinyl propionate, vinyldodecanoate, vinyl esters of alpha-branched carboxylic acids having 9 to 13 carbon atoms such as VeoVa9®, VeoValO®, VeoVall ®; Copolymers of vinyl acetate, 1 to 40% by weight of ethylene and preferably 1 to 60% by weight of acrylic esters of unbranched or branched alcohols having 1 to 15 C atoms, in particular n-butyl acrylate or 2-ethylhexyl acrylate;

Copolymers of 30 to 75 wt .-% vinyl acetate, 1 to 30 wt .-% vinyl laurate or vinyl ester of an alpha-branched carboxylic acid having 9 to 13 carbon atoms, and 1 to 30 wt .-% Acrylsäu ^¬ ester of unbranched or branched alcohols with 1 to 15 C atoms, in particular n-butyl acrylate or 2-Ethylhexylacry ^¬ lat, which may further comprise 1 to 40 wt .-% of ethylene can be contained ^¬ th;

Copolymers of vinyl acetate, 1 to 40% by weight of ethylene and 1 to 60% by weight of vinyl chloride;

Copolymers of one or more vinyl esters having 1 to 12 carbon atoms in the carboxylic acid radical such as vinyl acetate, vinyl propionate, vinyl laurate, vinyl esters of alpha-branched carboxylic acids having 5 to 13 carbon atoms such as VeoVa9 ^R , VeoVal0 ^R , VeoVall ^R , 1 to 40 wt. % Ethylene and 1 to 60% by weight vinyl chloride;

wherein in each case the said auxiliary monomers can be copolymerized in the stated amounts, and the information in wt .-% add up to each 100 wt .-%.

Also preferred are (meth) acrylic acid ester polymers, such as copolymers of n-butyl acrylate or 2-ethylhexyl acrylate or copolymers of methyl methacrylate with n-butyl acrylate and / or 2-ethylhexyl acrylate and optionally ethylene;

Styrene- (meth) acrylic acid ester copolymers of one or more monomers from the group of methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate; Vinyl acetate- (meth) acrylate copolymers of one or more monomers from the group of methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate and, where appropriate, ^¬ ethylene;

Copolymers of styrene and 1,3-butadiene;

wherein in each case the said auxiliary monomers can be copolymerized in the stated amounts, and the information in wt .-% add up to each 100 wt .-%. The monomer selection or the selection of the weight proportions of

Comonomers is made in such a way that in general a glass transition temperature Tg ^¬ from -50 ° C to + 50 ° C, preferably -10 ° C to + 30 ° C results. The glass transition temperature Tg of the polymers can be determined in a known manner by means of differential scanning calorimetry (DSC). The Tg can also be approximated by the Fox equation. After Fox TG, Bull. Am. Physics Soc. 1, 3, page 123 (1956): 1 / Tg = xl / Tgl + x2 / Tg2 + ... + xn / Tgn, where xn represents the mass fraction (wt .-% / 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 preparation of the homopolymers and copolymers is preferably carried out by the emulsion polymerization process, the polymerization temperature in general, but not necessarily <100 ° C.

The polymerization can be carried out independently of the polymerization process with or without the use of seed latex, with presentation of all or individual components of the reaction mixture, or with partial introduction and subsequent addition of the or individual constituents of the reaction mixture, or after the Dosierverfah ^¬ Ren without template are performed. All of the comonomers can be initially charged for the preparation of the dispersion (batch process), or some of the monomers are initially charged and the remainder is metered (semibatch process).

The initiation of the polymerization takes place with the water-soluble initiators or redox initiator combinations customary for emulsion polymerization. Examples of water-soluble initiators are the sodium, potassium and ammonium salts of peroxodisulfuric acid, hydrogen peroxide, tert-butyl hydroperoxide, potassium peroxodiphosphate, cumene hydroperoxide, isopropylbenzene monohydroperoxide. The initiators mentioned ^¬ the generally used in an amount of 0.001 to 0.02 wt .-%, preferably 0.001 to 0.01 wt .-%, based in each case on the Ge ^¬ samtgewicht of the monomers. Combinations of the stated initiators in combination with reducing agents are used as redox initiators. Suitable reducing agents are the sulfites and bisulfites of the alkali metals and of Ammo ^¬ nium, for example sodium sulfite, the derivatives of sulfoxylic acid such as zinc or Alkaliformaldehydsulfoxylate, example ^¬ example, sodium hydroxymethanesulfinate, ascorbic acid, and mixtures of the salts of 2-hydroxy-2-sulfinato Acetic acid and 2-hydroxy-2-sulfonato-acetic acid with sodium sulfite. The reducing agent ^¬ amount by weight in general, 0.001 to 0.03. ~ 6, Preference, from 0.001 to 0.015 wt .-%, each based on the Gesamtge ^¬ weight of the monomers.

To control the molecular weight substances can be used during the poly merisation ^¬ controlled. If regulators are used, they are to be polymerized, they usually Zvi ^¬ rule in amounts of 0.01 to 5.0 wt .-%, based on the Monomers, used and dosed separately or pre-mixed with Re ^¬ action components. Examples of such substances are n-dodecyl mercaptan, tert. Dodecylmercaptan, mercaptopropionic acid, methyl mercaptopropionate, isopropanol and acetaldehyde.

The polymerization is preferably carried out in the presence of

Protective colloid. Suitable protective colloids are the erfindungsge ^¬ MAESSEN vinyl alcohol copolymers, polyvinyl alcohols, polyvinyl nylacetale, polyvinyl pyrrolidones, polysaccharides in wasserlös ^¬ Licher form such as starches (amylose and amylopectin), celluloses and their methyl, hydroxyethyl or hydroxypropyl derivatives, poly (meth) acrylamide. Partially hydrolyzed or fully hydrolysed polyvinyl alcohols having a degree of hydrolysis of 80 to 100 mol%, in particular partially hydrolyzed polyvinyl alcohols having a degree of hydrolysis of 80 to 95 mol% and a Höppler viscosity, in 4 "aqueous solution of 1 to 30 are preferred as protective colloids in the polymerization mPas (Höppler method at 20 ° C, DIN 53015). Before are ^¬ is also given to partially hydrolyzed, hydrophobically modified polyvinyl ^¬ nylalkohole with a degree of hydrolysis of 80 to 95 mol%, and ei ^¬ ner Höppler viscosity, in 4 "6 aqueous solution of 1 to 30 mPas. Examples are partially hydrolyzed copolymers of vinyl acetate with hydrophobic comonomers, such as isopropenyl acetate, vinyl pivalate, vinyl ethylhexanoate, Vinylester of ge ^¬ saturated alpha-branched monocarboxylic acids having 5 or from 9 to 13 carbon atoms, dialkyl maleates and dialkyl pylmaleinat as diisopropyl maleate and diisopropyl fumarate, vinyl chloride, Vinyl alkyl ethers such as vinyl butyl ether, olefins such as ethene and decene. The proportion of hydrophobic units is preferably 0.1 to 10 wt .-%, based on the total weight of the partially hydrolyzed polyvinyl alcohol. It is also possible to use mixtures of the stated polyvinyl alcohols. Most preferred are partially hydrolyzed polyvinyl alcohols having a degree of hydrolysis of from 85 to 94 mol% and a Höppler viscosity, in 4% strength aqueous solution of from 3 to 15 mPas (Höppler method at 20 ° C., DIN 53015). The protective colloids mentioned are obtainable by methods known in the art and are generally used in an amount of 1 to 20 wt .-%, based on the total weight of the monomers, in the Po ^¬ lymerisation. If appropriate, mixtures of the said preferred protective colloids can also be used in each case with the vinyl alcohol copolymer according to the invention.

The polymerization can also be carried out in the presence of nonionic emulsifier, or in the presence of one or more of said protective colloids in combination with nonionic emulsifier. Suitable nonionic emulsifiers are surfactants such as alkyl polyglycol ethers or alkylaryl polyglycol ethers having 8 to 40 alkylene oxide units. Al koxylierte Cs to Ci6-alkanols, which oxides with C ₂ ^_ to C4 alkylene, especially ethylene oxide and propylene oxide or mixtures thereof are preferred are alkoxylated. The nonionic emulsifiers are generally added in an amount of 0.05 to 10 wt .-%, based on the total weight of the monomers, in the polymerization.

Preferably, only protective colloid is used for stabilization during the polymerization. After completion of the polymerization can be postpolymerized to the Restmonomerentfer- tion using known methods, generally by redox catalyst-initiated postpolymerization. Volatile residual monomers can also by Destil ^¬ lation, preferably under reduced pressure, and, where if they are removed by passing or passing over air or water vapor or inert entrained gases such as nitrogen. The aqueous dispersions obtainable therewith have a solids content of from 30 to 75% by weight, preferably from 50 to 60% by weight.

To prepare the water-redispersible polymer powders, the aqueous polymer dispersions of the base polymer are dried after addition of one or more protective colloids as drying aid. For this purpose, suitable protective colloids are the be ^¬ already previously mentioned in the polymerization as suitable protective colloids. Preferably, one or more of the OF INVENTION ^¬ to the invention vinyl alcohol copolymers are used as a drying aid. Particular preference is given to embodiments in which the vinyl alcohol copolymers of the invention are only as

Drying aid and not used in the polymerization who ^¬ . In general, the drying aid is used in a total amount of 0.1 to 20 wt .-%, preferably 1 to 7 wt .-%, each based on the total weight of the polymeric components of the aqueous dispersion of the base polymer.

Drying is carried out for example by means of fluidized bed ^¬ drying, freeze drying or spray drying. Preferably, the polymer dispersions are spray-dried. The spray-drying is carried out in conventional spray-drying plants, wherein the atomization can be carried out by means of single-, two- or multi-fluid nozzles or with a rotating disk. The outlet temperature is generally selected in the range from 45 ° C to 120 ° C, preferably 60 ° C to 90 ° C, depending on the system and the desired degree of drying.

During drying, a content of up to 2 wt .-% anti-foam agent, based on the total weight of po ^¬ lymeren components of the aqueous dispersion of the Basispoly- merisats, proved to be favorable. To increase the shelf life by improving the blocking, especially when powders with a low glass transition temperature, the powder obtained can be mixed with an antiblocking agent (anticaking agent), are wt .-%, based on the total weight of PO lymeren components of the aqueous dispersion of the base polymer, equipped before ^¬ preferably to 30 , Examples of antiblocking agents are calcium carbonate or magnesium carbonate, talc, gypsum, silica, kaolins, metakaolins, silicates with particle sizes preferably in Be ^¬ range from 10 nm to 100 ym.

The viscosity of the mixture to be atomized and dried can be adjusted via the solids content so that a value of <1000 mPas (Brookfield viscosity at 20 revolutions and 23 ° C.), preferably <500 mPas, especially preferably <250 mPas, is obtained , The solids content of the mixture to be atomized should be> 30% by weight, preferably> 40% by weight.

To improve the performance properties, further additives may be added before or during or after drying. Further, included in preferred embodiments, constituents of dispersion powder compositions are, for example, pigments, fillers, foam stabilizers, Hyd ^¬ rophobierungsmittel, plasticizers. In a particularly preferred embodiment, a silica sol is added to the aqueous polymer dispersions of the base polymer before or during the drying. Silica sols are aqueous solutions or aqueous suspensions of silica particles (SiO 2). The silica sols include colloidal silica, water glass or silica sol. The addition amount is in ERAL ^¬ NEN 0.1 to 10 wt .-%, wherein the information in wt .-% based on the solid content of the silica sols and refer to the Ge ^¬ samtgewicht of the polymeric components of the aqueous dispersion of the base polymer. The dispersion powder compositions of the invention can be used in the typical application areas. The dispersion powder compositions are mittein for modifying building compositions based on mineral binders such as cement, plaster or lime mortar, turned ^¬ sets. Examples of mineral binder are cement such as Portland, aluminate, trass, slag, magnesia, Phosphatze ^¬ ment, gypsum as calcium sulphate hemihydrate in the form of calcined gypsum, stucco or plaster of paris and / or lime as calcium hydroxide. In addition to the mineral binder, the building compositions contain fillers such as sand, for example silica sand or quartz powder, gravel, chalk, dolomite, light spar, respectively, in the manner customary for the relevant application depending ^¬ grain size and quantity. Further examples of fillers are fibers such as acrylate, polyethylene or cellulose fibers. Further customary for the construction of building materials additives are thickening agents, for example organic thickening agents such as cellulose ether and inorganic thickening ^¬ ckungsmittel such as bentonite, pigments, wetting agents, dispersing auxiliaries, preservatives, defoamers, Verfil- mung tool, antifreeze.

The dispersion powder compositions are preferably used for the production of sealing slurries, building adhesives, in particular tile adhesives or adhesives in thermal insulation composite systems, plasters, fillers, floor fillers, leveling compounds, joint mortars, repair mortars or crack-bridging plasters. Most preferred is the use in sealing slurries. A dry mortar formulation typical of a sealing slurry (without dispersion powder fraction) is for example: 10 to 50 parts by weight of cement, 10 to 50 parts by weight of quartz sand, 1.0 to 10 parts by weight of fibers, 0.1 to 1.0% by weight Parts Cement liquefier, 0.1 to 1.0 parts by weight defoamer. The dispersion powder compositions are preferably used in an amount of 5 to 50 wt .-%, each based on the Ge ^¬ samtgewicht the dry mortar formulations used. The ready-made mortar is manufactured by mixing with water, wherein the amount of water is preferably such that 25 to 60 parts by wt. Of water to 100 wt. Parts by Trockenfor ^¬ formulation can be used.

Further possible applications result from use in the adhesive and coating area, the latter for example as a coating agent for paper and textile.

The dispersion powder compositions can also be used as binders for sand, optionally in combination with mineral binders, for example for the consolidation of joint sand or for the consolidation of the surfaces of sand roads or gravel areas.

The following examples serve to further explain the invention:

Preparation of the vinyl alcohol copolymer:

In a 70 liter reactor with stirrer and condenser were the following

Substances submitted:

Methanol 12660 g t-butyl peroxypivalate (PPV, 75% solution) 31 g vinyl ester of versatic acid ^R l 0 (VeoVa ^R 10) 177 g

Vinyl acetate 3290 g

Vinyl sulfonate (25% solution) 233 g

While stirring under a nitrogen atmosphere, the solution was heated to 60 ° C and polymerized for 30 minutes. Thereafter, the following substances were added: An initiator solution of 125 g of PPV in 1,880 g of methanol was metered in ^¬ nerhalb 240 minutes.

A monomer mixture 1 with 999 g of VeoVa ^R 10 and 18661 g of vinyl acetate was metered in with a metering time of 180 minutes.

The monomer solution 2, 1319 g of a 25% aqueous solution of vinyl sulfonate was zudo ^¬ siert with a metering time of 195 minutes.

After metering, the reactor was locked, the pressure in the reactor increased to 0.2 bar and post-polymerized at 100 ° C for one hour. Thereafter, the polymer solution was cooled to 30 ° C and diluted with methanol to a 31 wt .-% solution. The Polymerlö ^¬ solution was overcoated without stirring with 38440 g of methanol and there ^{¬ added} after a mixture of 775 g of methanol and 657 g of 46% sodium hydroxide solution and stirred. After two hours, the solution was neutralized with 342 g of acetic acid (99.8%). Subsequently ^¬ WUR the methanol and the by-products ent ^¬ removed by steam stripping. After stripping, the vinyl alcohol copolymer was taken up in water and diluted to a 20% by weight solution. There was obtained a copolymer having 94.5 mol% of vinyl alcohol monomer units, 2.1 mol% of vinyl acetate monomer units, 2.3

Mol% VeoVa ^R 10 monomer units and 1.1 mol% vinyl sulfonic acid monomer units.

Preparation of the dispersion powders: Dispersion powder 1:

40 kg of an aqueous polymer dispersion (vinyl acetate-ethylene copolymer, Tg of -15 ° C, solids content 55%, stabilized with polyvinyl alcohol (Hoeppler viscosity of 5 mPas, degree of hydrolysis of 88 mol%)) were washed with

4.2 kg of an aqueous solution of a polyvinyl alcohol (Höppler viscosity of 13 mPa.s, degree of hydrolysis of 88 mol%, solids content 10%) and with 4 kg of an aqueous solution of the vinyl alcohol copolymer (solids content 20%) and with

8 kg of water mixed.

The dispersion thus obtained was sprayed by means of a two-fluid nozzle. The atomizing component used was 4 bar compressed air. The formed droplets were heated to 125 ° C in the air

DC dried. The dry polymer powder was mixed with 18% by weight of commercially available antiblocking agent (mixture of calcium carbonate and kaolin).

Dispersion powder 2:

The procedure was analogous to the preparation of dispersion powder 1, with the difference that before drying, additionally 1 kg of silica sol (Bindzil 2040, trade name of the company Ekanobel, solids content 40%) was added.

Dispersion powder 3 (comparison):

The procedure was analogous to the preparation of dispersion powder 1, with the difference that before drying, instead of the aqueous solution of the vinyl alcohol copolymer, 4 kg egg ^¬ ner aqueous solution of a polyvinyl alcohol (Hoeppler viscosity of 4 mPa s , Degree of hydrolysis of 88 mol%, solids content 20%) was added.

Dispersion powder 4 (comparison):

The procedure followed was analogous to the preparation of dispersion powder 3, with the difference that prior to drying, an additional 1 kg of silica sol (Bindzil 2040, trade name of the company Ekano- bei, solids content 40%) was added.

Production and testing of mortar compounds: To prepare the coating composition, the individual constituents of the formulation given in Table 1 were added to a Toni mixer (commercial laboratory mixer) in the following order with mixing:

First, the inorganic binders (cements and anhydrite), then the fillers, then the respective dispersion powder and finally the other additives.

The mixture was then mixed homogeneously for 15 minutes.

With the resulting dry mixture, the aqueous coating composition was prepared with a water-solid material ^¬ factor of 0.265 in analogy to EN 196-1.

Table 1:

Application Testing: The coating mortars thus obtained were each treated, as described in EN 1348, as a thin layer of mortar

Trowel on a vertically erected concrete slab aufgetra ^¬ gene. Thereafter, the coating mortar was applied in each case with a toothed trowel with a toothing 8mm x 8mm so that the webs were applied horizontally from left to right.

In order to ensure the trowel a defi ned ^¬ wet coating thickness after smoothing of the webs, it is critical that the webs are stable. So you should not sag or even flow.

The stability was rated qualitatively with a grading system of 1 to 6. The rating system ranges from

1 = no change in the bars and no rounding of the edges until

6 = the mortar flows.

The results of the evaluation are summarized in Table 2:

Table 2:

When applying the coating mortar for mounting the webs and the Aufziehverhalten was assessed.

The Aufziehverhalten was rated qualitatively with a grading system from 1 to 6. The rating system ranges from 1 = excellently smooth fitting without noticeable resistance when combing the webs

to

6 = very tough, power-consuming and stiff towing.

Finally, the stickiness of the coating on stirring was tung mortar with a trowel and when spread on the lower ^¬ basic assessed qualitatively with a rating system of 1 = no noticeable tack

to

6 = extremely sticky behavior.

The results are summarized in Table 3. Table 3:

With the vinyl alcohol copolymer as a drying aid (Ex. 1 and Example 2) has been obtained dispersion powders which in mortar formulations, surprisingly, both the non-sag properties of the thus heat-treated coating mortar (Table 2) Improvement ^¬ th, and its processability (Table 3: slight adhesive ^¬ good smoothness and suppleness).

Claims

Water-redispersible polymer powder compositions containing vinyl alcohol copolymer, which are ^obtained by radically polymerizing one or more ethylenically unsaturated monomers in the presence of protective colloid and/or emulsifier in an aqueous medium, and the resulting aqueous polymer dispersion after addition of protective colloid is ^dried as a drying aid, characterized in that

during the polymerization and/or drying, as a protective colloid, one or more vinyl alcohol copolymers ^containing a) 80 to 99 mol% vinyl alcohol monomer units, b) 0.5 to 10 mol% monomer units, which are derived from vinyl esters unbranched or branched alkylcarboxylic acids with 3 to 18 carbon atoms, c) 0.5 to 10 mol% monomer units, which are ethylenically unsaturated monomers with one or more functional groups, selected from the group comprising carboxylic acid residue, sulfonic acid -residue, quaternized amine residue, phosphoric ^acid residue, and their salts, and d) 0 to 5 mol% vinyl acetate monomer units, the information in mol% adding up to 100 mol%, used who ^¬ the .

Water-redispersible polymer powder composition according to claim 1, characterized in that the vinyl alcohol copolymer contains monomer units b) which are derived from a vinyl ester of a-branched monocarboxylic acids with 9 to 10 carbon atoms. Water-redispersible polymer powder composition according to claim 1 or 2, characterized in that the vinyl alcohol copolymer contains monomer units c) which are ^derived from vinyl sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and their ^salts .

Water-redispersible polymer powder composition according to claims 1 to 3, characterized in that the vinyl alcohol copolymer d) contains 1 to 4 mol% of vinyl acetate monomer units.

Water-redispersible polymer powder composition according to claims 1 to 4, characterized in that a silica sol is added to the aqueous polymer dispersion before or during drying.

Process for the production of water-redispersible polymer powder compositions, wherein one or more ethylenically unsaturated monomers are radically polymerized in the presence of protective ^colloid and/or emulsifier in an aqueous medium, and the resulting aqueous ^polymer dispersion is dried after the addition of protective colloid as a drying aid is, characterized in that during the polymerization and / or drying as a protective colloid one or more vinyl alcohol copolymers ^containing a) 80 to 99 mol% vinyl alcohol monomer units, b) 0.5 to 10 mol% monomer units, which are derived from vinyl esters of unbranched or branched alkylcarboxylic acids with 3 to 18 carbon atoms, c) 0.5 to 10 mol% monomer units, which are derived from ethylenically unsaturated monomers with one or more functional groups, selected from the group comprising carboxylic acid residue, sulfonic acid residue, quaternized amine residue, phosphoric ^acid residue, and their salts, and d) 0 to 5 mol% vinyl acetate monomer units, the information in mol% each adding up to 100 mol%, whoever uses ^it .

7. The method according to claim 6, characterized in that one or more vinyl alcohol copolymers are only used as a drying aid during drying.

8. Use of the water-redispersible polymer powder compositions according to claims 1 to 5 for modifying building material compositions based on mineral ^binders .

9. Use of the water-redispersible polymer powder compositions according to claims 1 to 5 for the production of sealing slurries, construction adhesives, plasters, fillers, floor fillers, leveling compounds, joint mortars, repair mortars or crack-bridging plasters.

10. Use of the water-redispersible polymer powder compositions according to claims 1 to 5 as coating agents for paper and textiles.

11. Use of the water-redispersible polymer powder compositions according to claims 1 to 5 as binders for sand.