EP3634921A1

EP3634921A1 - Method for producing an aqueous dispersion, and redispersible dispersion powder produced therefrom

Info

Publication number: EP3634921A1
Application number: EP18727837.9A
Authority: EP
Inventors: Christian Schmidtke; Ekkehard Jahns; Torben Gaedt; Martin Winklbauer; Klaus Seip; Iris LOESCHER
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2017-06-09
Filing date: 2018-06-06
Publication date: 2020-04-15
Also published as: WO2018224519A1; CN110831913B; CN110831913A; US11685696B2; US20200207671A1

Abstract

The invention relates to a method for producing a redispersible dispersion powder, to the redispersible dispersion powder which can be obtained according to the method, to an aqueous dispersion which can be obtained according to step (1) of the method, to a construction material composition containing the redispersible dispersion powder and/or the aqueous dispersion, to the use of the redispersible dispersion powder in a construction material composition, and to the use of the aqueous dispersion for producing a redispersible dispersion powder.

Description

Process for the preparation of an aqueous dispersion and redispersible dispersion powder prepared therefrom

The present invention relates to a process for the preparation of a redispersible dispersion powder, the redispersible dispersion powder obtainable by this process, an aqueous dispersion obtainable after step (1) of this process, and a building material composition containing the redispersible dispersion powder and / or the aqueous dispersion, the use of the redispersible dispersion powder in a building material composition and the use of the aqueous dispersion for the preparation of a redispersible dispersion powder.

Aqueous dispersions containing polymer particles are used in building material compositions in order to improve the flexibility, the adhesive properties and / or the flowability of the building material compositions.

However, aqueous dispersions are disadvantageous because the building material compositions are generally required as dry blends. Furthermore, aqueous dispersions are disadvantageous in terms of storage (for example due to frost damage, microorganism attack, etc.) and of transport. In particular, upon prolonged storage originally dispersed uniformly dispersed polymer particles can agglomerate and thus prevent a uniform distribution of the polymer particles in the building material composition. Therefore, dispersion powders are required, which are redispersible and contain polymer particles, in order to improve the flexibility, the adhesion properties and / or the flowability of the building material compositions, as stated above.

A particularly expedient method for converting an aqueous dispersion into a redispersible dispersion powder is spray-drying. In this case, the aqueous dispersion is sprayed in a stream of hot air and dehydrated. In order to ensure spray-drying of the dispersion and the redispersibility of the dispersion powder, a spray aid is added to the aqueous dispersion. Redispersible dispersion powders therefore usually contain polymer particles and a water-soluble spray aid. In addition, emulators may be included.

No. 5,922,796 A describes a redispersible dispersion powder comprising a powder of a water-insoluble, film-forming polymer obtainable from at least one ethylenically unsaturated monomer, at least one nonionic emulsifier and at least one water-soluble compound selected from polyelectrolytes which belong to the weak polyacids and contain carboxyl groups as acid groups. No. 6,036,887 A describes redispersible granules comprising at least one active material in the form of a hydrophobic liquid, at least one nonionic emulsifier and at least one water-soluble compound selected from polyelectrolytes which belong to the weak polyacids and contain carboxyl groups as acid groups. WO 03/097721 A1 describes the use of water-soluble polymers consisting of monomers containing monoethylenically unsaturated acid groups in acidic, partially or completely neutralized form and further monomers copolymerized with these monomers as drying agents for the preparation of redispersible powder and / or pulverulent, polymeric dispersant , It is described as preferred that the acid groups of the monomers are at least partially neutralized before, during or after polymerization.

WO 97/26295 A1 discloses redispersible polymer powders based on a mixture of water-insoluble polymer and a water-soluble polymeric atomizing protective colloid which contains carboxylic acid groups and is not neutralized or partially neutralized.

DE 43 20 220 A1 discloses the use of polymers of acrylamide or acrylic acid ester monomers which carry a sulfonic acid group in the side chain, and further free-radically copolymerizable monomers as auxiliaries in the spray-drying of aqueous dispersions.

However, the spray aids described in the prior art have disadvantages. For example, they are unsuitable for the spray-drying of certain aqueous dispersions or dye the dispersion powder. Above all, there is still room for improvement in the redispersibility of the dispersion powder. In addition, there is a great need to improve the application properties of the redispersible dispersion powder to the effect that the made with the redispersible dispersion powder building material is easy to process, in particular an optimal pot life of about 0.5 h - 2 h.

It was therefore the object of the present invention to provide an improved process for preparing redispersible dispersion powders and particularly readily redispersible dispersion powders having improved application properties. This object is achieved by the process according to the invention for producing a redispersible dispersion powder comprising the steps

(1) Mix at least

(i) an aqueous dispersion, wherein the dispersion contains particles, the particles containing at least one polymer I, wherein the polymer I contains monomer units which are composed of at least one ethylenically unsaturated monomer; and

(ii) a polyacid II containing monomer units composed of at least one ethylenically unsaturated monomer containing a sulfonic acid group or a salt of this group;

wherein in step (1) an additive containing a polyoxyalkylene group, preferably a polyoxyethylene group, wherein the degree of ethoxylation is 6 to 50, is present, the additive

(A) is admixed as a further component of the mixture from step (1), or (B) is applied in a preceding step by emulsion polymerization on the surface of the particles, or

(C) is polymerized in a preceding step as a monomer unit in the polymer I of the particles;

and wherein the dispersion resulting from step (1) has a pH of <4;

(2) drying the dispersion resulting from step (1) to obtain the redispersible dispersion powder.

It has surprisingly been found that the preparation of redispersible dispersion powders can be improved if a polyacid II is used as a spraying assistant and the spray drying is carried out at a pH of <4. This is probably due to the acidic pH-enhanced formation of hydrogen bonds between the particles containing the polymer I and the polyacid II. This effect can be enhanced if an additive acting as an emulsifier containing a polyoxyalkylene group is added. It is believed that in this way a protective cover is formed around the particles, which protects the particles during the spray-drying before the filming.

Furthermore, the present invention relates to a redispersible dispersion powder obtainable by the process according to the invention. During the drying and / or after drying, an antiblocking agent is preferably added to the redispersible dispersion powder obtained by the process according to the invention in order to prevent irreversible agglomeration of the polymer particles of the redispersible dispersion powder. The redispersible dispersion powder according to the invention is distinguished by a particularly good redispersibility. This improved property is presumably due to the protective coating of the polyacid and, optionally, the emulsifier around the particles formed by the process according to the invention. The invention further relates to an aqueous dispersion obtainable after step (1) of the process. The dispersion is particularly advantageous for the preparation of the redispersible dispersion powder due to the low pH for the reasons explained above.

Furthermore, the invention relates to a building material composition containing

the redispersible dispersion powder according to the invention, and / or

the aqueous dispersion according to the invention.

The building material composition has improved properties with regard to processability, flexibility, adhesion and possibly flowability.

Furthermore, the invention also relates to the use of the inventive redispersible dispersion powder in a building material composition. Furthermore, the invention also relates to the use of the aqueous dispersion according to the invention for producing a redispersible dispersion powder.

The invention will be described in more detail below. In this context, the following terms are important.

The term "weight%" (also called mass fraction) refers to the percentage of the respective component in relation to the sum of all components by weight, unless otherwise stated.The term "Vol%" denotes the percentage of the respective component in relation to the sum of all components measured by volume, unless otherwise stated. Furthermore, the sum of all percentages of the specified and unspecified components of a composition is always 100%.

The term "comprising" means that, in addition to the specific features mentioned, further, non-specifically named features may also be present.The term "containing" should also be understood. The term "consisting of" means that only the specific features mentioned are included.

The preferred embodiments of the invention will be explained below. The preferred embodiments are preferred alone and in combination with each other.

As already mentioned above, in one embodiment the invention relates to a process for the preparation of a redispersible dispersion powder comprising the steps

(1) Mix at least

(A) is admixed as a further component of the mixture from step (1), or

(B) is applied in a preceding step by emulsion polymerization on the surface of the particles, or

and wherein the dispersion resulting from step (1) has a pH of <4;

(2) drying the dispersion resulting from step (1) to obtain the redispersible dispersion powder. The term "redispersible dispersion powder" or "redispersible powder" denotes a polymer in powder or particle form, which can be redispersed when a solvent, in particular a polar solvent such as water, is added. The redispersible dispersion powders or the dispersion resulting with the solvent, preferably with water, can be used in building material compositions in order to improve the workability, the flexibility, the adhesive properties and / or the flowability of the building material compositions.

Usually, the polymer particles of the redispersible dispersion powder are obtained by emulsion polymerization. This is a process of radical polymerization of hydrophobic monomers in an aqueous phase. Preferably, emulsifiers are added to solubilize the hydrophobic monomers. Suitable emulsifiers are described below and in particular include those having a polyoxyalkylene group. Typically, the emulsifiers added in the emulsion polymerization remain adhered to the surface of the formed polymer particles, so that the emulsifier is applied to the surface of the particles by the emulsion polymerization. In addition, a water-soluble initiator is added to initiate the polymerization. Typical initiators include thermally decomposing free radical generators, e.g. Peroxides such as Na2S20s or

(NH4) 2S208 or azo compounds, photochemical decomposing radical formers, for example azo-bis (isobutyronitrile) (AIBN) or free-radical generators formed by redox reactions, for example the combination of ammonium peroxodisulfate and ascorbic acid. After the emulsion polymerization, a drying process is carried out to obtain the redispersible dispersion powder. Suitable drying methods are described below. In order to ensure drying of the dispersion and the redispersibility of the dispersion powder, a spray aid is added to the aqueous dispersion. Suitable spray aids for the process according to the invention for the preparation of the redispersible dispersion powders are described below. After drying, the desired polymer particles are obtained in combination with the spraying assistant. The term "particles" or "polymer particles" in connection with the inventive redispersible dispersion powders refers to polymer particles having a specific particle size D _x based on a particle size distribution, wherein x% of the particles have a diameter which is smaller than the D _x value. The Dso particle size is the median particle size distribution. The particle size distribution can be measured, for example, by means of dynamic light scattering ISO 22412: 2008. The particle size distribution can be given as volume distribution, surface distribution or number distribution. According to the present invention, the D _x value refers to the number distribution, where x% of the total number of particles has a smaller diameter. A D ₅ o value of the particles in the dispersion resulting from step (1) of 50 to 1000 nm is preferred.

Due to reversible agglomeration of the particles during drying, the D 50 value of the particles of the redispersible dispersion powder is larger, and it has a D 50 value of 10 to 300 μηι preferred for the particles of the redispersible dispersion powder. The particle size measurement of the dispersion powders is based on optically dynamic, digital image processing. A dispersed stream of particles passes two LED strobe light sources, the shadow projections of the particles being detected by two digital cameras. The dry measurement is carried out with the device Camsizer XT from Retsch GmbH using a dispersing pressure of 50 kPa.

The particles of the redispersible dispersion powder according to the invention comprise at least one polymer I which contains monomer units which are composed of at least one ethylenically unsaturated monomer.

The term "wherein the polymer I contains monomeric units composed of at least one ethylenically unsaturated monomer" refers to a polymer I which is based on at least one ethylenically unsaturated monomer In the polymerization, the ethylenically unsaturated double bonds are converted into the polymer chain in that, for example, a radical breaks the C = C double bond (chain start) and the resulting radical with CC single bond attacks the next ethylenically unsaturated monomer on the C = C double bond and so on, so that a polymer chain is formed (growth reaction) Therefore, the monomer units contained in the polymer I correspond to the underlying ethylenically unsaturated monomers except for the fact that the C = C double bonds are present only as CC single bonds due to the polymerization and the monomer units in a polymer chain present. Preferably, the ethylenically unsaturated monomer according to the present invention is a compound having the following structural formula:

R ¹ R ³

> =

R ² R ⁴

where R ¹ , R ² , R ³ and R ⁴ independently of one another are selected from the group consisting of -H, - (C ₁ -C ₆ ) -alkyl, -O (C ₁ -C ₆ ) -alkyl, -COOR ⁵ , - ( C ₆₎ AlkylCOOR ^5, -OC (0) _(Ci-C6) alkyl, - (C ₂ -C ₆₎ alkenyl, and - (C6-Cio) aryl; and

wherein R ^{5 is} - (Ci-Cg) alkyl.

The prefix "C _x -C _y " denotes the possible number of carbon atoms in each group The term "(C 1 -C 9) alkyl", alone or as part of another group, denotes a linear aliphatic carbon chain containing from 1 to 9 carbon atoms or a branched aliphatic carbon chain containing 4 to 9 carbon atoms. The term "(C 1 -C 6) alkyl", alone or as part of another group, denotes a linear aliphatic carbon chain containing from 1 to 6 carbon atoms or a branched aliphatic carbon chain containing from 4 to 6 carbon atoms, non-limiting examples (Ci-Cg ) Alkyl groups or (Ci-Ce) alkyl groups include methyl, ethyl, n-propyl, iso-propyl, n-butyl, 2-butyl, iso-butyl, tert-butyl, n-pentyl, 1-methylbutyl, 2 Methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, 1 Ethylpropyl, n-hexyl, 1, 1-dimethylpropyl, 1, 2-dimethylpropyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1, 1-dimethylbutyl, 1, 2-dimethylbutyl, 1, 3 Dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethyl- 1-methylpropyl and 1-ethyl-2-methylpropyl 2-ethylhexyl, n-octyl, iso-decyl, 2-propyl-heptyl, cyclohexyl, iso-nonyl, iso-tridecyl, iso-pentyl, 3,5,5-trimethyl 1-hexyl, 2-isopropyl-5-methylhexyl. The (C 1 -C 6) alkyl group may be optionally substituted with one or more substituents independently selected from the group consisting of -F, -Cl, -OH and -CF 3. The term "(C 2 -C 6) alkenyl" denotes a linear or branched alkyl group having 2, 3, 4, 5 or 6 carbon atoms and having one, two or three carbon-carbon double bonds. Non-limiting exemplary (C 2 -C 6) alkenyl groups include vinyl (ethenyl), 1-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl, and 1-hexenyl -C) alkenyl group may optionally be substituted with one or more substituents independently selected from the group consisting of -F, -Cl, -OH and -CF3.

The term "(C 6 -C 10) aryl" refers to mono- or bicyclic aromatic compounds having 6 or 10 carbon atoms, non-limiting exemplified (C 6 -C 10) aryl groups include phenyl and naphthyl The (C 6 -C 10) aryl group may optionally be substituted with one or more substituents independently selected from the group consisting of -F, -Cl, -OH and -CF ₃ , - (Ci-C ₆ ) alkyl or -0 (dC ₆ ) alkyl substituted.

It may optionally continue to be used in minor amounts, for example in less than 10 wt .-%, preferably less than 8 wt .-%, more preferably less than 6 wt .-%, auxiliary monomers.

Examples of these further monomers are ethylenically unsaturated mono- and dicarboxylic acids, such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid and maleic acid, aconitic acid, mesaconic acid, crotonic acid, citraconic acid, acryloyloxypropionic acid, methacryloxypropionic acid, vinylacetic acid, monomethylitaconate, monomethyl fumarate, monobutyl fumarate, acrylic acid anhydride, hydride, methacrylic anhydride, maleic anhydride, or itaconic anhydride, acrylamidoglycolic acid and methacrylamidoglycolic acid, acrylamide, methacrylamide, and isopropylacrylamide, substituted (meth) acrylamides, such as N, N-dimethylamino (meth) acrylate; 3-dimethylamino-2,2-dimethylpropyl-1- (meth) acrylate, N, N-dimethylaminomethyl (meth) acrylamide, N- (4-morpholinomethyl) (meth) acrylamide, diacetoneacrylamide; Acetoacethoxyethylmethacrylat; N-methylol (meth) acrylamide, polyethylene oxide (meth) acrylate, methoxypolyethylene oxide (meth) acrylate, acrolein, methacrolein; N- (2-methacryloxyethyl) ethylene urea, 1- (2- (3-allyloxy-2-hydroxypropylamino) ethyl) imidazolidin-2-one, ureido (meth) acrylate, 2-ethyleneureidoethyl methacrylate.

Furthermore, the following auxiliary monomers are suitable: ethylenically unsaturated, hydroxyalkyl-functional comonomers, such as methacrylic acid and acrylic acid hydroxy (Ci-C5) -alkylester t as Hydroxyethyl, hydroxypropyl and 4-hydroxybutyl acrylate, hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylates, 4-hydroxybutyl (meth) acrylate, glycidyl (meth) acrylate, and also N-vinylpyrrolidone and vinylimidazole. Particularly preferred are acrylic acid, methacrylic acid, acrylamide, hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate.

Further examples of the auxiliary monomers are phosphorus-containing monomers z. As vinylphosphonic acid and allylphosphonic acid. Also suitable are the mono- and diesters of phosphotonic acid and phosphoric acid with hydroxyalkyl (meth) acrylates, especially the monoesters. Also suitable are diesters of phosphonic acid and phosphoric acid which are simply acrylate with a hydroxyalkyl (meth) and additionally simply with a different alcohol, for. As an alkanol, esterified. Suitable hydroxyalkyl (meth) acrylates for these esters are those mentioned below as separate monomers, in particular 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate. Corresponding dihydrogenphosphate termonomers include phosphoalkyl (meth) acrylates, such as 2-phosphoethyl (meth) acrylate, 2-phosphopropyl (meth) acrylate, 3-phosphopropyl (meth) acrylate, phosphobutyl (meth) acrylate and 3-phospho- 2-hydroxypropyl (meth) acrylate. Also suitable are the esters of phosphonic acid and phosphoric acid with alkoxylated hydroxyalkyl (meth) acrylates, for example the ethylene oxide condensates of (meth) acrylates, such as H ₂ C =C (CH 3) COO (CH ₂ CH ₂ O) nP (OH) 2 and

H2C = C (CH 3) COO (CH ₂ CH ₂ O) n P (= O) (OH) 2, where n is 1 to 50. Also suitable are phosphoalkyl crotonates, phosphoalkyl maleates, phosphoalkyl fumarates, phosphodialkyl (meth) acrylates, phosphodialkyl crotonates and allyl phosphates. Further suitable phosphorous group-containing monomers are described in WO 99/25780 and US Pat. No. 4,733,005, to which reference is hereby made.

Also suitable are vinylsulfonic acid, allylsulfonic acid, sulfoethyl acrylate, sulfoethyl (meth) acrylate, sulfopropyl acrylate, sulfopropyl (meth) acrylate, 2-hydroxy-3-acryloxypropyl-isulfonic acid, 2-hydroxy-3-methacryloxypropylsulfonic acid, styrenesulfonic acids and 2-acrylamido. 2-methyl propane sulfonic acid. Suitable styrenesulfonic acids and derivatives thereof are styrene-4-sulfonic acid and styrene-3-sulfonic acid and the alkaline earth or alkali metal salts thereof, for. As sodium styrene-3-sulfonate and sodium styrene-4-sulfonate, poly (allyl glycidyl ether) and mixtures thereof, in the form of various products called Bisomer ® Laporte Performance Chemicals, UK. This includes z. Bisomer® MPEG 350 MA, a methoxypolyethyl-glycol monomethacrylate.

The functional groups of the monomers contribute to the mediation of the colloidal stabilization of the composition, in particular even if the entire formulation also contains fillers, such as calcium carbonate. In this case, the crosslinking takes place either by reaction with one another or by addition of a further crosslinking agent. Preferably, the crosslinking takes place only after the actual film formation. In a preferred embodiment, the polymer I contains monomer units selected from at least one ethylenically unsaturated monomer selected from the group consisting of ethylene, propylene, butadiene, styrene, vinyl acetate, vinyl chloride, vinyl ethers, vinyl esters, acrylic acid esters, methacrylic acid esters, and mixtures of previously mentioned monomers are constructed.

In a preferred embodiment, the polymer I is selected from the group consisting of

(ia) styrene (meth) acrylate copolymers,

(ib) styrene-butadiene copolymers,

(ic) (meth) acrylate copolymers, and

(id) ethylene-vinyl acetate copolymers.

Particularly preferred are styrene (meth) acrylate copolymers.

In a further particularly preferred embodiment, the polymer I is a styrene-2-ethylhexyl acrylate copolymer, a styrene-n-butyl acrylate copolymer or a styrene-butadiene copolymer. According to the invention, the spray aid used is a polyacid II which comprises monomer units which are composed of at least one ethylenically unsaturated monomer containing a sulfonic acid group.

Similarly as explained in connection with the polymer I, the term "polyacid II, which contains monomer units which are made up of at least one ethylenically unsaturated monomer containing a sulfonic acid group or a salt of this group" refers to a polyacid II which At least one ethylenically unsaturated monomer is derived, wherein the ethylenically unsaturated monomer contains a sulfonic acid group As described in connection with the polymer I, in the polymerization the ethylenically unsaturated double bonds are converted into the polymer chain The monomer units contained in the polyacid II correspond Therefore, the underlying ethylenically unsaturated monomers except for the fact that the C = C double bonds due to the polymerization are present only as CC single bonds and the monomer units are present in a polymer chain The sulfonic acid groups are not involved in the polymerization, but are in the side chain of the ethylenically unsaturated monomer.

The "ethylenically unsaturated monomer containing a sulfonic acid group" is preferably a compound having the following structural formula: wherein R ^{1b is selected} from the group consisting of -SO 3 H or a salt thereof, - (C 1 -C ₆ ) alkyl, -O (C 1 -C ₆ ) alkyl, -COOR ⁶ , -CONHR ⁶ , - (C ₁ -C ₆ ) alkylCOOR ⁵ , (C ₁ -C ₆ ) alkylCONHR ⁵ , -OC (O) (C ₁ -C ₆ ) alkyl, -NHC (O) (C ₁ -C 6) alkyl, - (C ₂ -C 6) alkenyl, and - ( C6-Cio) aryl, wherein at least one carbon atom of the groups - (Ci-C ₆ ) alkyl, -0 (Ci-C ₆ ) alkyl, -COOR ⁶ , -CONHR ⁶ , - (Ci-C ₆ ) AI- kylCOOR ^5, - (Ci-C ₆₎ AlkylCONHR ^5, -OC (0) (Ci-C ₆₎ alkyl, -NHC (0) _(Ci-C6) alkyl, - (C ₂ -C ₆₎ alkenyl, and - (C 6 -C 10) aryl is substituted by at least one -SO ₃ H group or a salt of this group; and

wherein R ² , R ³ and R ^{4 are} independently selected from the group consisting of -H, - (C ₁ -C ₆ ) alkyl, -O (C ₁ -C ₆ ) alkyl, -COOR ⁵ , - (C ₁ -C ₆ ) alkylCOOR ⁵ , -OC (O) (C ₁ -C ₆ ) alkyl, - (C ₂ -C ₆ ) alkenyl, and - (C ₆ -C 10) aryl;

wherein R ^{5 is} -H or - (Ci-Cg) alkyl; and where

R ^{6 is} - (C ¹ -C ₉ ) alkyl.

In another preferred embodiment, R ^{1b is selected} from the group consisting of -SO ₃ H or a salt thereof, - (C ₁ -C ₆ ) alkyl, -O (C ₁ -C ₆ ) alkyl, -COOR ⁶ , - (C ₁ -C ₆ ) Alkyl COOR ⁵ , -OC (0) (Ci-C ₆ ) alkyl, - (C ₂ -C ₆ ) alkenyl, and - (C ₆ -Cio) aryl selected, wherein at least one carbon atom of the groups - (Ci-C ₆ ) alkyl, -O (Ci-C ₆ ) alkyl, -COOR ⁶ , - (Ci-C ₆ ) alkyl COOR ⁵ , -OC (0) (Ci-C ₆ ) alkyl, - (C ₂ -C ₆ ) Alkenyl, and - (C ₆ -C 10) aryl is substituted with at least one -SO ₃ H group or a salt of this group; and

wherein R ^{5 is} -H or - (Ci-Cg) alkyl; and where

R ^{6 is} - (C ¹ -C ₉ ) alkyl.

In a preferred embodiment, R ^{1b is selected} from the group consisting of -SO 3 H or a salt thereof, - (C ₁ -C ₆ ) alkyl, -O (C ₁ -C ₆ ) alkyl, -OC (O) (C ₁ -C ₆ ) alkyl , - (C ₂ -C ₆ ) alkenyl, and - (C ₆ -Cio) aryl selected, where at least one carbon atom of the groups - (Ci-Ce) alkyl, -0 (Ci-C6) alkyl AI, -OC ( 0) is (Ci-C ₆ ) alkyl, - (C ₂ -C ₆ ) alkenyl, and - (C ₆ -Cio) aryl substituted with at least one -S0 ₃ H group or a salt of this group.

In a preferred embodiment, the polyacid II contains monomer units consisting of at least one ethylenically unsaturated monomer containing at least one sulfonic acid group or a salt thereof, selected from the group consisting of vinylsulfonic acid, 2-hydroxy-3- (prop-2-enoyloxy ) propane-1-sulfonic acid, 2-hydroxy-3 - [(meth) acryloyloxy] propane-1-sulfonic acid, 3-allyloxy-2-hydroxypropane-1-sulfonic acid, styrene-3-sulfonic acid, 3- (meth) allyloxy benzene-1-sulphonic acid, α-methylstyrenesulphonic acid, α-ethylstyrenesulphonic acid, allyloxybenzenesulphonic acid, (meth) allyloxybenzenesulphonic acid, maleic acid bis (3-sulphopropyl) ester, maleic acid bis (2-sulphoethyl) ester, itaconic acid bis ( 3-sulfopropyl) ester, itaconic acid bis (2-sulfoethyl) ester, 2-propene-1-sulfonic acid, 2-methyl-2-propene-1-sulfonic acid, 4-vinylphenyl sulfonic acid and salts of the abovementioned acids and mixtures of the above mentioned monomers, and at least one further ethylenically unsaturated monomer he selected from the group consisting of Acrylic acid, methacrylic acid, maleic acid, itaconic acid and salts of the aforementioned acids and mixtures of the aforementioned monomers are constructed.

In a further preferred embodiment, the polyacid II monomer units which are composed of the ethylenically unsaturated monomers acrylic acid, methacrylic acid and 2-methyl-2-propene-1-sulfonic acid or the corresponding salts.

In a particularly preferred embodiment, the polyacid II monomer units, which are composed of the ethylenically unsaturated monomers acrylic acid, methacrylic acid and 2-methyl-2-propene-1-sulfonic acid or the corresponding salts, wherein the weight fraction of the monomers of the Acrylic acid 10 to 40 wt .-%, the methacrylic acid 10 to 40 wt .-% and the 2-methyl-2-propene-1-sulfonic acid 10 to 40 wt .-%, based on the total weight of the monomers making up the Polymer II is constructed. In a further particularly preferred embodiment, the polyacid II monomer units, which are composed of the ethylenically unsaturated monomers acrylic acid and 2-methyl-2-propene-1-sulfonic acid or the corresponding salts, wherein the weight fraction of the monomers the acrylic acid is from 20 to 80% by weight and the 2-methyl-2-propene-1-sulfonic acid is from 20 to 80% by weight, based on the total weight of the monomers constituting the polymer II.

In a further particularly preferred embodiment, the polyacid II monomer units, which are composed of the ethylenically unsaturated monomers methacrylic acid and 2-methyl-2-propene-1-sulfonic acid or the corresponding salts, wherein the weight fraction of the monomers of methacrylic acid 20 to 80 wt .-% and the 2-methyl-2-propene-1-sulfonic acid 20 to 80 wt .-%, based on the total weight of the monomers of which the polymer II is constructed.

In a particularly preferred embodiment, the polyacid II contains monomer units which are composed of at least one allylic monomer containing at least one sulfonic acid group or a salt of this group. In this connection, an allylic monomer containing at least one sulfonic acid group means a monomer containing a 2-propenyl group and at least one sulfonic acid group or a salt thereof. Under 2-propenyl is to be understood as a monounsaturated C3 group which may be bound to the monomer via an oxygen atom or is directly linked to the sulfonic acid group. Preferably, the 2-propenyl group is linked directly to the sulfonic acid group. Optionally, the 2-propenyl group can carry further substituents, preferably a methyl substituent, or be unsubstituted. Due to autoinhibition of the allylic monomer units during free-radical polymerization, cleavage of partial chains can lead to lower molecular weights of the allylic monomer units and thus of the resulting polymers (see "George Odian, Principles of Polymerization, 4th Edition, Wiley-Interscience, 2004") This effect is surprisingly advantageous for the present invention. In a further particularly preferred embodiment, the polyacid II contains monomer units which comprise at least one allylic monomer containing at least one sulfonic acid group or a salt thereof, selected from the group consisting of 3-allyloxy-2-hydroxypropane-1-sulfonic acid , 3- (Meth) allyloxybenzene-1-sulfonic acid, allyloxybenzenesulfonic acid, (meth) allyloxybenzenesulfonic acid, 2-propene-1-sulfonic acid, 2-methyl-2-propene-1-sulfonic acid and salts of the aforementioned acids and mixtures of the aforementioned monomers , and optionally at least one further ethylenically unsaturated monomer selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, itaconic acid and salts of the aforementioned acids and mixtures of the abovementioned monomers.

The polymer I and the polyacid II can be present independently of one another as a monopolymer (homopolymer) or as a copolymer. The copolymers include random copolymers, gradient copolymers, alternating copolymers, block copolymers and graft copolymers. It is preferred that the copolymers be present as linear random copolymers or as linear block copolymers.

It is preferable that the polymer I has a weight average molecular weight of less than 2,500,000 g / mol or less than 1,500,000 g / mol, more preferably from 50,000 to 1,500,000 g / mol. The weight average molecular weight may be determined by gel permeation chromatography, e.g. in THF. For this purpose, the liquid polymer dispersion is dissolved in a large excess of tetrahydrofuran (THF), for example with a polymer concentration of 2 milligrams of polymer per milliliter of THF, and the insoluble fraction separated with a membrane filter of 200 nm mesh size.

It is preferable that the polyacid II has a weight average molecular weight of less than 250,000 g / mol or less than 150,000 g / mol, more preferably from 1,000 to 50,000 g / mol. The average molecular weight can be determined as weight average by gel permeation chromatography as described in the examples.

The polymerization can be carried out by bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization or precipitation polymerization. A suitable free radical, anionic and / or cationic initiator may be used. Suitable initiators are known to the person skilled in the art. For the polymer I, the emulsion polymerization using a radical initiator as stated above is preferred. For the polyacid II, the solution polymerization using a radical initiator as mentioned above is preferable.

The process according to the invention is characterized in that in process step (1) a dispersion is obtained by mixing (i) at least one aqueous dispersion comprising particles comprising at least one polymer I and (ii) a polyacid II, characterized the dispersion has a pH of <4. Particularly preferred is a pH of <3, in particular a pH in the range of 1 to 3. The pH value can be measured with a pH meter (Ahlborn ALMEMO 2590-9, pH combination electrode: Schott 6381), preferably in accordance with DIN ISO 976 (December 2016). As stated above, at this low pH, the formation of a protective coating of the polyacid II around the polymer particles is possible. In this way, the polyacid II not only acts as a spraying aid, but the formed protective casing probably also has a positive influence on the redispersibility of the polymer particles obtainable by the process according to the invention. The pH value is strongly influenced by the pH of the polyacid II and can be influenced by the degree of neutralization of the polyacid. When the polyacid II is used as a solution, by adjusting the pH of the solution containing the polyacid II, for example, by adding an acid or base to the solution, it is possible to predict the pH of the dispersion resulting from step (1).

The polyacid II can be used in the process of the invention as an aqueous solution or as a solid. Preference is given to using an aqueous solution which already has a pH of <4, preferably <3, particularly preferably in the range from 1 to 3. By mixing the two components (i) and (ii), an aqueous dispersion having a pH of <4, preferably <3, particularly preferably in the range from 1 to 3, is then obtained in process step (1).

The concentrations of the aqueous dispersion containing the particles and the amount of the polyacid II or, if appropriate, the concentration of the aqueous solution containing the polyacid II are preferably selected so that the following ratios of polyacid II based on the weight of the particles or of the Combination of particles and polyacid II based on the total weight of the dispersion can be met.

The dispersion resulting from step (1) contains the combination of

Particles containing at least one polymer I, and

Polyacid II

preferably in an amount of 10-70 wt .-% based on the total weight of the dispersion.

In a preferred embodiment, the dispersion resulting from step (1) contains the combination

Particles containing at least one polymer I, and

Polyacid II

in an amount of 30-70% by weight, more preferably in an amount of 30-60% by weight, particularly preferably in an amount of 40-55% by weight, based on the total weight of the dispersion.

The wt .-% - information regarding the combination of

Particles containing at least one polymer I, and Polyacid II

refer in each case to the amount of solids (without water) based on the total weight of the dispersion. The amount of the polyacid II relative to the particles (each as a solid) can be varied over a wide range.

The polyacid II is preferably in an amount of 2 to 50 wt .-%, more preferably 5 to 40 wt .-%, more preferably 5 to 15 wt .-%, based on the weight of the particles containing at least one polymer I. used.

In process step (2) of the process according to the invention, the dispersion resulting from step (1) is dried at the above-indicated pH to obtain the redispersible dispersion powder.

The drying can be carried out by roller drying, spray drying, drying in the fluidized bed process, by substance drying at elevated temperature or other conventional drying methods. The preferred range of the drying temperature is between 50 ° C and 230 ° C. Alternatively, a freeze-drying can take place.

In a preferred embodiment, the process according to the invention comprises, as step (2), the spray-drying of the dispersion resulting from step (1) in order to obtain the redispersible dispersion powder. Preference is given to an inlet temperature of the dry air in the range of 100 ° C to 250 ° C, preferably 130 ° C to 220 ° C and a starting temperature in the range of 30 ° C to 120 ° C, preferably 50 ° C to 100 ° C. Particularly preferred is an inlet temperature in the range of 130 to 150 ° C and an outlet temperature of 60 to 85 ° C. To dry the suspensions, a spray drier from GEA Niro of the Mobile Minor type MM-I can be used. It is dried using a two-fluid nozzle in the head of the tower. The drying is preferably dried with nitrogen, which is blown in co-current with the drying material from top to bottom. Drying is preferably carried out with 60 to 100 kg / h, more preferably 80 kg / h of drying gas. The powder discharged from the drying tower, with the drying gas, can be separated from the drying gas by means of a cyclone.

In a preferred embodiment, the method according to the invention further comprises the step

(3) mixing the redispersible dispersion powder from step (2) with

(iii) an anti-blocking agent. Anti-blocking agents reduce the agglomeration of the polymer particles in the redispersible dispersion powder. Non-limiting examples of antiblocking agents are bentonite, quartz sand, quartz flour, kieselguhr, silica, colloidal silica gel, microsilka, fumed silica, or precipitated silica, which may optionally be hydrophobized, clay, magnesium hydrosilicates, talc (magnesium silicate hydrate), calcium hydrosilicates, kaolin (aluminum silicate hydrate), Mica,

Xonolite, calcium sulfate, magnesium sulfate, barium sulfate, titanium dioxide, calcium carbonate, magnesium carbonate, Ca / Mg carbonate and mixtures of the aforementioned agents. Preferred antiblocking agents are silica, talc, calcium carbonate, kaolin and mixtures thereof. The proportion of the antiblocking agent is preferably between 4 and 20% by weight, based on the total weight of all constituents of the redispersible polymer powder. In a particularly preferred embodiment, the antiblocking agent is talc, calcium carbonate and / or silica in a proportion of between 4 to 20 wt .-% based on the total weight of all components of the redispersible polymer powder. Additionally or alternatively, one of the antiblocking agents described above may be added during drying. This does not necessarily have to be the same antiblocking agent which is added after drying. Preference is given to adding silica, which may optionally be hydrophobized. If the antiblocking agent is added during drying, the proportion is preferably between 0.1-4.0% by weight, more preferably between 0.5-2.0% by weight, based on the total weight of all constituents of the redispersible polymer powder.

As already described above, further advantages of the method according to the invention result from the fact that an additive is used which acts as an emulsifier. It is believed that the emulsifier enhances the formation of the protective coating of the polyacid II around the polymer particles. Preferably, therefore, an additive is used in the process according to the invention, which acts as an emulsifier. The additive is particularly preferably used in step (1) of the process. Additives having a polyoxyalkylene group have proved to be particularly advantageous. In a further preferred embodiment of the process according to the invention, therefore, in step (1) an additive comprising a polyoxyalkylene group, preferably a polyoxyethylene group, the degree of ethoxylation being from 6 to 50, is mixed in with the additive

(A) is admixed as a further component of the mixture from step (1), or

(b) in a preceding step, by emulsion polymerization on the surface of

Particles is applied, or

(c) is polymerized in a preceding step as a monomer unit in the polymer I of the particles. It is also possible according to the invention that the options (a), (b) and (c) are used in combination. Option (a) is to be understood as meaning that the additive is admixed as a further component of step (1), wherein the additive may be added as an aqueous solution or as a solid. Option (b) is to be understood as meaning that the additive is already present in the emulsion polymerization when the polymer particles containing the polymer I are prepared. As a result, the additive is applied to the surface of the polymer particles, but no covalent bonds are formed, but hydrogen bonds are formed between the polymer chain and the additive. Option (c) is to be understood as meaning that the additive is introduced via the side chain of a monomer which is present in the preparation of polymer I, so that the polymer chain obtained not only has the monomer units characteristic of polymer I, which are more detailed above but also other monomer units resulting from an ethylenically unsaturated monomer containing a polyoxyalkylene group in the side chain. Such monomers are also referred to as polyoxyalkylenated, ethylenically unsaturated monomers according to the invention.

The polyoxyalkylene group may be a polyoxy (C 1 -C 4) alkylene group, preferably a polyoxyethylene group. The polyoxyalkylene group of the additive is preferably a polyoxyethylene group wherein the degree of ethoxylation is 6 to 50. It is particularly preferred that the degree of ethoxylation is 10 to 35.

The degree of ethoxylation refers to the average number of ethoxy groups (-CH2-CH2-O-) per molecule of additive or per monomer unit in the case of option (c).

In a particularly preferred embodiment A of the process according to the invention, in step (1), an additive comprising a polyoxyethylene group, the degree of ethoxylation being from 6 to 50, being admixed, wherein the additive

(A) is admixed as a further component of the mixture from step (1), and / or

(B) is applied in a preceding step by emulsion polymerization on the surface of the particles.

(A) is added to the mixture of step (1) as a further component.

In another particularly preferred embodiment B of the process according to the invention, in step (1) an additive containing a polyoxyethylene group wherein the degree of ethoxylation is from 6 to 50 is admixed, wherein the additive

(B) is applied in a preceding step by emulsion polymerization on the surface of the particles. In another particularly preferred embodiment C of the process according to the invention, in step (1), an additive comprising a polyoxyethylene group, wherein the degree of ethoxylation is 6 to 50, is admixed, the additive

(c) is polymerized in a preceding step as a monomer unit in the polymer I of the particles.

With respect to the embodiments A, B and C, it is particularly preferable that the degree of ethoxylation of the polyoxyethylene group of the additive is 10 to 35. The additives used according to option (a) or (b) are preferably polyoxyalkylenated (C 6 -C 22) alcohols, (C 6 -C 30) -carboxylic acids, (C 6 -C 30) -alkylamines, sorbitan esters, triglycerides or alkylphenols, wherein the polyoxyalkylene group is preferably one of the above-mentioned polyoxyalkylene groups, especially a polyoxyethylene group. The term "(C 6 -C 22) alcohol" denotes a linear aliphatic carbon chain containing from 6 to 22 carbon atoms or a branched aliphatic carbon chain containing from 4 to 22 carbon atoms, the carbon chain being substituted by at least one hydroxy group Exemplary compounds include cis-9-hexadecen-1-ol, trans-9-octadecene-1-ol, cis-9-octadecene-1-ol, 1-decanol, 1-hexadecanol, 1-heptadecanol, 1-octadecanol, iso tridecanol, 2-propyl-4-methylhexanol, 2-propyl-5-methylhexanol, 2-iso-propyl-4-methylhexanol, 2-iso-propyl-5-methylhexanol, 2-propyl-4,4-dimethylhexanol, 2 Ethyl 2-methylheptanol and 2-ethyl-2,5-dimethylhexanol.

Non-limiting example compounds of (C6-C30) carboxylic acids include capric, undecanoic, lauric, tridecanoic, myristic, pentadecanoic, palmitic, stearic and cerotic acids.

Sorbitan esters are cyclic sorbitol esters of (C6-C3o) carboxylic acids. The term "triglyceride" refers to the triesters of glycerol with (C 6 -C 30) carboxylic acids, wherein the (C 6 -C 30) carboxylic acids can also be exchanged by transesterification with a polyalkylene oxide The triglycerides may be of vegetable or animal origin Compounds include pork fat, butter oil, linseed oil, olive oil, palm oil, soybean oil and coconut oil.

The term alkylphenol refers to an ortho, meta or para substituted alkyl substituted phenol. The term alkyl in the context of alkylphenols refers to a linear or branched aliphatic saturated or unsaturated carbon group which, unless otherwise stated, contains from 1 to 36 carbon atoms. Non-limiting exemplified (C 1 -C 36) alkyl groups in connection with alkylphenols include n-heptyl, n-octyl, 2-ethylhexyl, iso-octyl, nonyl, iso-nonyl, decyl, iso-decyl, cis-6-hexadecene, 2-hexylethyl, and 2-propylheptyl. In a further preferred embodiment, the additive containing a polyoxyalkylene group in options (a) and (b) is selected from the group consisting of (C6-C22) -alcohol ethoxylates, (C6-C22) -alcohol ether sulfonates and (C6-C22) Alcohol ether sulfates, and is polymerized in option (c) as a polyoxyethylenated ethylenically unsaturated monomer.

By the term (C6-C22) -alcohol ether sulfates, also called (C6-C22) -alcohol polyglycol ether sulfates (or (C6-C22) -alcohol ether sulfonates) are the sulfates (or sulfonates) of the adducts of polyethylene glycol to a (C6-C22 ) To understand alcohol. It is particularly preferred that the additive containing a polyoxyalkylene group in options (a) and (b) is a (C6-C22) alcohol ethoxylate and / or a (C6-C22) alcohol ether sulfonate or sulfate. In one embodiment, the additive containing a polyoxyalkylene group in options (a) and (b) is a C 12 -alcohol ether sulfonate or sulfate (dodecyl ether sulfate).

The additives used according to option (a) or (b) are preferably in an amount of 0.2-10% by weight, more preferably in an amount of 0.2-5% by weight, more preferably in an amount of 0.5-5 wt .-%, based on the total weight of the dispersion used. In the case of option (c), suitable monomers are preferably an amount of 0.2-10% by weight, more preferably in an amount of 0.2-5% by weight, particularly preferably in an amount of 0.5% by weight. 5 wt .-%, based on the total weight of the dispersion, copolymerized in the polymer I of the particles.

The preparation of the polymer dispersion is usually carried out in the presence of at least one surface-active compound. A detailed description of suitable protective colloids can be found in Houben-Weyl, Methods of Organic Chemistry, Volume XIV / 1, Macromolecular Materials, Georg Thieme Verlag, Stuttgart, 1961, p. 41 1 to 420. Suitable emulsifiers are also found in Houben-Weyl, Methods of Organic Chemistry, Volume 14/1, Macromolecular Materials, Georg Thieme Verlag, Stuttgart, 1961, pages 192 to 208.

Suitable emulsifiers are both anionic, cationic and nonionic emulsifiers. Emulsifiers whose relative molecular weights are usually below those of protective colloids are preferably used as surface-active substances. In particular, it has proven useful to use exclusively anionic emulsifiers or a combination of at least one anionic emulsifier and at least one nonionic emulsifier.

Useful nonionic emulsifiers are araliphatic or aliphatic nonionic emulsifiers, for example ethoxylated mono-, di- and trialkylphenols (EO degree: 3 to 50, alkyl radical: C4-C10), ethoxylates of long-chain alcohols (EO degree: 3 to 100, alkyl radical: C) ₈ -C ₃ 6) and polyethylene oxide / polypropylene oxide homo- and copolymers. These may comprise the alkylene oxide units randomly distributed or in copolymerized form in the form of blocks. Well suited z. B. EO / PO block copolymers. Ethoxylates of long-chain alkanols (alkyl radical Cr C30, average degree of ethoxylation 5 to 100) and, with particular preference, those with a linear C 12 -C 20 -alkyl radical and an average degree of ethoxylation of from 10 to 50 and also ethoxylated monoalkylphenols. Suitable anionic emulsifiers are for example alkali metal and ammonium salts of Al kylsulfaten (alkyl radical: C8-C22), ethoxylated sulfuric acid monoesters of alkanols (EO degree: from 2 to 50, alkyl radical: _{_Ci2-Ci8)} and ethoxylated alkylphenols (EO units: 3 to 50, alkyl radical: C4-C9), of alkylsulfonic acids (alkyl radical: C12-C18) and of alkylarylsulfonic acids (alkyl radical: Cg-C-is). Further suitable emulsifiers can be found in Houben-Weyl, Methods of Organic Chemistry, Volume XIV / 1, Macromolecular Materials, Georg-Thieme-Verlag, Stuttgart, 1961, pp. 192-208. Also suitable as anionic emulsifiers are bis (phenylsulfonic acid) ethers or their alkali metal or ammonium salts which carry a C ₄ -C ₂ -alkyl group on one or both aromatic rings. These compounds are well known, for. From US4,269,749 A, and commercially available, for example as Dowfax® 2A1 (Dow Chemical Company).

Suitable cationic emulsifiers are preferably quaternary ammonium halides, e.g. Trimethylcetylammonium chloride, methyltrioctylammonium chloride, benzyltriethylammonium chloride or quaternary compounds of N-C6-C20-alkylpyridines, -morpholines or -imidazoles, e.g. B. N-Laurylpyridinium chloride.

As already mentioned above, the present invention relates to a redispersible dispersion powder obtainable by the process according to the invention. The redispersible dispersion powder can be redispersed particularly well, which is due to the structural properties which result from the production process according to the invention. In particular, the polymer particles are influenced by the polyacid II with respect to the redispersibility, which can be explained by the fact that the polyacid II by hydrogen bonds, which form particularly well at the acidic pH of the dispersion used in the process, a protective cover to the Forms polymer particles. The redispersible dispersion powder preferably also contains an antiblocking agent. Suitable antiblocking agents are those mentioned above.

The redispersible dispersion powder may contain, in addition to the antiblocking agent, other additives, e.g. Flame retardants, antioxidants, light stabilizers, biocides, fibrous and powdery fillers or reinforcing agents or antistatic agents, defoamers, thickeners, and other additives, or mixtures thereof. These can either be added after drying, or they can be added before drying, ie in step (1). Only the antiblocking agent is preferred to be added only after drying.

A particularly preferred additive is a defoamer, which in turn is preferably added in step (1). The invention further relates to an aqueous dispersion obtainable after step (1) of the process. The acidic pH of the dispersion is advantageous for the spray-drying and the redispersibility of the redispersible dispersion powders which can be prepared in this way. Furthermore, the invention therefore also relates to the use of the aqueous dispersion according to the invention for producing a redispersible dispersion powder.

the redispersible dispersion powder according to the invention, or

- The aqueous dispersion of the invention.

The building material composition has improved properties in terms of processability, flexibility, adhesion, ductility, abrasion resistance, water-tightness, density, flexural and cohesive strength and / or long-term stability. The building material composition can be used as a coating of surfaces, e.g. To repair unevenness or to make the surface more resistant to corrosion by environmental influences, for example by CO2, SO2, C or salts. Furthermore, the crack-bridging properties can be improved. Furthermore, the invention also relates to the use of the inventive redispersible dispersion powder in a building material composition. It is particularly advantageous that the building material composition can be used as dry mixtures, because the redispersible dispersion powder according to the invention is particularly readily redispersible.

In particular, the use of the redispersible dispersion powder according to the invention for the following building material compositions is advantageous or the following building material compositions according to the invention are preferred:

Tile glue,

Tile grouts,

Mortar for heat insulation systems,

Stucco, smoothing plaster and top plasters,

Patch and repair mortar,

Self-balancing underlaying and overlaying,

Waterproof sealing slurries (membranes),

Joint filler, and

Powder coating.

These building material compositions are also called base material-modified building material compositions. The building material composition may contain a mineral binder.

Mineral binders such as lime, gypsum, cement or mixtures thereof are known in the art. They are used, for example, for the production of mortars and concretes used. Cements in accordance with DIN EN 197-1 (November 201 1) or comparable standards may be considered as cement, for example white cement or gray cement, such as Portland cement, may be used as the cement. The term "cement" also includes calcium aluminate cements, calcium sulfo-aluminate cements (CSA cements) and mixtures thereof.

Calcium aluminate cements include minerals of the formula CaO x Al 2 O 3. They can be obtained, for example, by melting calcium oxide (CaO) or limestone (CaCC) with bauxite or aluminate. Calcium aluminate cements comprise about 20 to 40 wt .-% CaO, up to 5 wt .-% S1O2, about 40 to 80 wt .-% Al2O3 and up to about 20 wt .-% of Fe ₂ 0. ₃ Calcium aluminate cements are defined in the standard DIN EN 14647 (January 2006).

Calcium sulfo-aluminate cements can be prepared from tricalcium aluminate (3 CaO x Al 2 O 3), anhydrite (CaSO ₄ ), calcium sulfate hemihydrate (CaSO ₄ × 0.5 H ₂ O) and / or gypsum (CaSO ₄ × 2 H ₂ O). be presented.

Mineral binders also include latent hydraulic binders such as microsilica, meta-tocol, aluminosilicates, fly ash, activated clay, pozzolans or mixtures thereof. A latent hydraulic binder we only in the presence of a basic activator hydraulically. The alkaline medium for activating the binders usually consists of aqueous solutions of alkali metal carbonates, alkali metal fluorides, alkali metal hydroxides, alkali metal aluminates and / or alkali metal silicates, such as e.g. soluble water glass.

Further, depending on the application, conventional additives such as plasticizers, thickeners or other rheology aids, fillers, air entraining agents, defoamers, accelerators, retarders, wetting aids, etc. may be added.

The invention will be further described by the following examples. Examples

Determination of the molecular weight of the polyacid II:

The sample preparation for the molecular weight determination was carried out by dissolving copolymer solution in the GPC eluent so that the polymer concentration in the GPC eluent is 0.5% by weight. Thereafter, this solution was filtered through a syringe filter with Polyethersulfonmembran and pore size 0.45 μηη. The injection volume of this filtrate was 50-100 μΙ.

The determination of the average molecular weights was carried out on a GPC device

the company Waters with the type name Alliance 2690 with UV detector (Waters

2487) and RI detector (Waters 2410). The following settings and conditions were used: Columns: Shodex SB-G Guard Column for SB-800 HQ series and Shodex OHpak SB 804HQ and 802.5HQ (PHM gel, 8 x 300 mm, pH 4.0 to 7.5)

Eluent: 0.05 M aqueous ammonium formate / methanol mixture = 80:20 (by volume) flow rate: 0.5 ml / min

Temp .: 50 ° C

Injection: 50 to 100 μΙ

Detection: Rl and UV

The molecular weights of the copolymers were determined relative to the polyacrylic acid standards of PSS Polymer Standards Service GmbH. The molecular weight distribution curves of the polyacrylic acid standards were determined by light scattering.

Provision of polymer dispersions and spray aids: Dispersion 1:

The dispersion contains a styrene-2-ethylhexyl acrylate copolymer which still contains monomer units resulting from the stabilizing auxiliary monomers hydroxyethyl methacrylate (HEMA) and 2,3-epoxypropyl methacrylate (GMA). The dispersion has a solids content of 55% by weight. The polymer has a glass transition temperature of -15 ° C and a particle size of about 600 nm. The dispersion further contains 0.5% by weight of (C 16 -C 18) -alkyl ethoxylate having a degree of ethoxylation of 18, 0.3 Wt .-% of a mixture of sodium di-ethyl-hexylsulphosuccinate / isotridecanol ethoxylate with a degree of ethoxylation of 4 and 0.1 wt.% Ci2-i4-Alkyl (EO) ₃ oS0 ₄ Na. Dispersion 2:

The dispersion contains a styrene-2-ethylhexyl acrylate copolymer which also contains monomer units resulting from the stabilizing auxiliary monomer monomer methoxy poly (oxyethylene) methacrylate having a degree of ethoxylation of 17 and of 2,3-epoxypropyl methacrylate (GMA). The dispersion has a solids content of 56.5% by weight. The poly-mer has a glass transition temperature of -13 ° C and a particle size of about 510 nm. The dispersion further contains 0.5 wt.% Polyoxyethylenated Ci2-C ₄ alcohol ethoxylates with a degree of ethoxylation of 4, sulfated and 0.3% sodium lauryl sulfate.

Dispersion 3:

The dispersion contains a styrene-butadiene copolymer which still contains monomer units resulting from the stabilizing auxiliary monomers hydroxyethyl methacrylate (HEMA) and acrylic acid. The dispersion has a solids content of 51% by weight. The polymer has a glass transition temperature of 0 ° C and a particle size of about 160 nm. The dispersion further contains 1 wt.% Ci2-i ₄ -alkyl (EO) ₄ S0 ₄ Na, 0.7 wt.% Isotridecanolethoxylate with a degree of ethoxylation of 4 and 0.5% by weight of isotridecanol ethoxylates having a degree of ethoxylation of 8.

Dispersion 4: The dispersion contains, in addition to the styrene-butadiene copolymer from dispersion 3, 3% by weight (based on the solids content of the dispersion) of isotridecanol ethoxylate with a degree of ethoxylation of 25. Spray auxiliaries (SHM)

Spray aid 1:

In a reaction vessel equipped with reflux condenser, stirrer, thermometer, dropping funnel and nitrogen fumigation, 180 g of water, 94.8 g of Na-Methylpropensulfonsäure and 3 g of 2,2'-azobis (2-methylpropionamidine) dihydrochloride (Wako V50) submitted and on 80 ° C tempered. After reaching the temperature, a solution of 3 g of 2,2'-azobis (2-methylpropionamidine) dihydrochloride, 108 g of acrylic acid, 129 g of methacrylic acid and 150 g of water was metered in over a period of 36 minutes while stirring at 80 ° -90 ° C. , The reaction solution was stirred for 1 h. At 80 ° C and then cooled to room temperature. The resulting product was a clear polymer solution having a solids content of 52.0% by weight, a pH of 1.4, and a molecular weight M _w of about 2400 g / mol.

Spray Aid 1A:

The spray aid 1A was adjusted to a pH of 2.4 with NaOH. Spray Aid 1 B:

The spray aid 1A was adjusted to a pH of 3.4 with NaOH.

Comparison spraying aid 1 C:

Spray Aid 1A was adjusted to pH 4.2 with NaOH.

Comparative Spray Aid 1 D:

The spray aid 1A was adjusted to a pH of 6.1 with NaOH. Spray aid 1 E:

The spraying aid 1 A was adjusted to a pH of 1.9 with H2SO4. Comparative Spray Aid 2:

In a reaction vessel equipped with reflux condenser, stirrer, thermometer, dropping funnel and nitrogen gassing, 140 g of water and 2 g of 2,2'-azobis (2-methylpropionamidine) dihydrochloride (Wako V50) were initially charged and heated to 70.degree. After reaching the temperature, a solution of 2 g of 2,2'-azobis (2-methylpropionamidine) dihydrochloride, 3 g of 3-mercaptopropionic acid, 100 g of acrylic acid and 100 g of water over a period of 36 min. Added. The reaction solution was stirred for 1 h. At 80 ° C and then cooled to room temperature. The resulting product was a clear polymer solution having a solids content of 46.3% by weight, a pH of 1.4, and a molecular weight M _w of about 1600 g / mol.

Comparative Spray Aid 2A: An aliquot of Spray Aid 2 was adjusted to pH 6.0 with NaOH. Comparative Spray Aid 2B:

An aliquot of Spray Aid 2A was adjusted to pH 1.4 with H2SO4.

Comparative Spray Aid 3:

A polyacrylic acid having a pH of ~ 2 and a molecular weight M _w of about 5000 g / mol, which is manufactured by BASF and is available under the trade name Sokalan PA 25 XS.

Comparative Spray Aid 4:

A polyacrylic acid having a pH of ~ 8 and a molecular weight M _w of about 8000 g / mol, which is manufactured by the BASF and under the trade name Sokalan PA 30 is available

Spraying aid 5:

In a reaction vessel equipped with reflux condenser, stirrer, thermometer, dropping funnel and nitrogen fumigation, 200 g of water, 81 g of Na-Methylpropensulfonsäure and 1 .5 g of 2,2'-azobis (2-methylpropionamidine) dihydrochloride (Wako V50) submitted and on 73 ° C tempered. After reaching the temperature, a solution of 1.5 g of 2,2'-azobis (2-methylpropionamidine) dihydrochloride, 250 g of methacrylic acid and 130 g of water was metered in over a period of 1 hour with stirring at 73 ° -81 ° C. The reaction solution was stirred for 1 h. At 80 ° C and then cooled to room temperature. The resulting product was a clear polymer solution having a solids content of 50.3 wt%, a pH of 1.4, and a molecular weight M _w of about 1400 g / mol.

Spray Aid 6:

280 g of water and 195 g of Na-2-acrylamido-2-methylpropanesulfonic acid (AMPS) were introduced into a reaction vessel equipped with reflux condenser, stirrer, thermometer, dropping funnel and nitrogen gassing and heated to 18 ° C. While stirring, 70 g of a 50% sodium hydroxide solution at 18 ° C were added dropwise. 68 g of acrylic acid, 2.8 g of 2,2'-azobis (2-methylpropionamidine) dihydrochloride (Wako V50) and 4 g of mercaptoethanol were then metered in over a period of 10 minutes with stirring. The reaction solution was stirred at 70 to 80 ° C for 1, 5 hrs and then cooled to room temperature. The resulting product was a clear polymer solution having a solids content of 48.1% by weight, a pH of 0.8 and a molecular weight M _w of about 8400 g / mol.

Spray aid 7:

In a reaction vessel equipped with reflux condenser, stirrer, thermometer, dropping funnel and nitrogen fumigation, 350 g of water and 313 g of Na- 2-acrylamido-2-methylpropanesulfonic acid (AMPS) were introduced and tempered to 18 ° C. With stirring, 12 g of a 50% strength sodium hydroxide solution at 18 ° C were added dropwise. Then, with stirring, 27 g of acrylic acid, 2.8 g of 2,2'-azobis (2-methylpropionamidine) dihydrochloride (Wako V50) and 6 g of mercaptoethanol a period of 14 min. The reaction solution was stirred at 70 to 80 ° C for 1, 5 hrs and then cooled to room temperature. The resulting product was a clear polymer solution having a solids content of 48.5% by weight, a pH of 0.8 and a molecular weight M _w of about 7400 g / mol.

Preparation of a polymer powder by spray drying:

The spray drying was carried out with a laboratory dryer (Niro Atomizer) from Niro with nitrogen as the drying gas. The aqueous dispersion to be dried in each case with the water-soluble spray aid was sprayed with a solids content of 40-60% over a two-component nozzle. The inlet temperature of the dryer gas was 130 to 140 ° C, the outlet temperature was 60 to 70 ° C. 0.5 to 1% by weight (based on the solids content of the feed solution) of silica and 9% by weight (based on the solids content of the feed solution) of talc Luzenac (Imerys) were used as antiblocking agents.

Determination of redispersibility of the dispersion powder:

Films were prepared from the spray-assisted dispersion (SHM) composition shown in Table 1 and their redispersion tested. For this purpose, the liquid dispersion (5 g of solid) in 10-15 ml of water was mixed with the described amount of the respective spraying aid and dried at 60 ° C. overnight. About 0.5 g of the resulting film was taken up at room temperature in 10 mL of distilled water with stirring (200 rpm). Rapid redispersion within a few minutes has shown that these dispersion systems are also extremely spray-dryable and that a redispersible powder (RDP) is obtained.

The redispersion was evaluated as follows:

Complete redispersion within a few minutes: very good

Almost complete redispersion within a few minutes: Good

Incomplete redispersion (parts of the film still visible): Moderate

Large parts of the film insoluble or no redispersion: Bad

Table 1 Redispersibility of the redispersible dispersion powders (n.b. = not determined)

No. DisperSHM Quantity SHM on pH RedisperRedispersion solids content value gability

Dispersion SHM of the film of the powder i) 1 1 10 wt.% 1 .4 Very good Very good ü) 1 1 7 wt.% 1 .4 Very good Very good

Iii) 1 1A 10% w / w 2.4 Very good n.b.

iv) 1 1 B 10 wt% 3.4 Moderate n.b.

v) (Ref. Ex.) 1 Ref.-1 C 10 wt.% 4.2 Poor n.b.

vi) (Ref.-Ex.) 1 Ref.-1 D 10% by weight 6.1 Poor Bad vii) 1 1 E 10 wt% 1 .9 Very good nb

viii) (Ref. Ex.) 1 Ref.-2 10 wt.% 1 .4 Very good Very good ix) (Ref. Ex.) 1 Ref.-2A 10 wt.% 6.0 Poor n.b.

x) (Ref.-Ex.) 1 Ref.-2B 10 wt.% 1 .4 Good n.b.

xi) (ref. Ex.) 1 ref. 3 10 wt.% ~ 2 very good very good xii) (ref. Ex.) 1 ref. 4 10 wt.% ~ 8 bad n.b.

xiii) 1 5 7 wt.% 1 .4 very good very good xiv) 1 5 10 wt.% 1 .4 very good very good xv) 2 1 10 wt.% 1 .4 very good very good xvi) 3 1 10% by weight 1 .4 poor nb

xvii) 4 1 10 wt% 1 .4 Very good Very good xviii) 1 6 10 wt% 0.8 Poor n.b.

xix) 1 7 10 wt% 0.8 Poor n.b.

It turns out that it is advantageous for redispersibility if the pH of the dispersion is <4 and if the spray assistant is a polyacid composed of at least one ethylenically unsaturated monomer containing a sulfonic acid group. Particularly preferred is the use of a spraying aid which is based on at least one allylic monomer containing at least one sulfonic acid group.

Production of a Building Material Composition with a Redispersible Dispersion Powder: Building material compositions according to Table 2 were prepared using the redispersible dispersion powder of the present invention. Example 1 here is a comparative example in which instead of the redispersible dispersion powder, a styrene-acrylate copolymer (Acronal) was used.

Table 2:

From the above-described dispersion-modified mineral building material mixture, the pot life was evaluated. The pot life is the period of use in which the polymer-modified building material in the prepared state has a viscosity and creaminess suitable for processing, so that it can be applied to the application substrate with a suitable aid (trowel, doctor blade, etc.). If this time is exceeded, the building material can no longer pass smoothly on the application substrate. A pot life of 0.5-2 hours is desirable, whereas faster systems are difficult to process and extremely slow systems (pot life> 3 hours) delay the next steps.

From the dispersion-modified mineral building material mixture, a thin film was produced (height: 2.0 mm, width 12.0 cm and length 20 to 25 cm). The appearance of the dried building material was tested. If this was homogeneous (no segregation), apparently smooth, with no bumps or cracks, it was found to be good (rated OK in Table 3). If the pH of the dispersion is greater than 4, processing is not possible (see Dispersion Powder xii) in Table 3). If the spray aid does not contain a polymer with sulfonic acid groups, processing is not possible (see dispersible powder xi) and viii) in Table 3). In addition, processing is only possible if the spray aid is based on at least one allylic monomer containing at least one sulfonic acid group.

Properties of the building material composition

Composition Used RDP Appearance Pot life

Ex 4 i) OK 50 min

Ex.2 ü) OK 50 min

Ref.-Ex.8 viii) (Ref.-Ex.) Processing was not possible

Ref.-Ex.5 xi) (Ref.-Ex.) Processing was not possible

Ref.-Ex.9 xii) (Ref.-Ex.) Processing was not possible

Ex.3 xiii) OK 2 h

Ex.6 xv) OK 2 h

Ex.7 xvii) Few cracks 2 h

Claims

claims

A process for producing a redispersible dispersion powder comprising the steps

(1) Mix at least

(A) is admixed as a further component of the mixture from step (1), or

and wherein the dispersion resulting from step (1) has a pH of <4;

The method of claim 1 further comprising the step

Mixing the redispersible dispersion powder from step (2) with

(iii) an anti-blocking agent.

3. The method according to claim 1 or 2, wherein the resulting from step (1) dispersion preferably has a pH of <3.

4. The method according to any one of claims 1 to 3, wherein the polymer I contains monomer units selected from at least one ethylenically unsaturated monomer selected from the group consisting of ethylene, propylene, butadiene, styrene, vinyl acetate, vinyl chloride, vinyl ethers, vinyl esters, acrylic acid esters , Methacrylsäureestern, and mixtures of the aforementioned monomers are constructed.

5. The method according to any one of claims 1 to 4, wherein the polymer I is selected from the group consisting of

(ia) styrene (meth) acrylate copolymers,

(ib) styrene-butadiene copolymers,

(ic) (meth) acrylate copolymers, and

(id) ethylene-vinyl acetate copolymers.

6. The method according to any one of claims 1 to 5, wherein the polyacid II contains monomer units selected from at least one ethylenically unsaturated monomer containing at least one sulfonic acid group or a salt thereof, selected from the group consisting of vinylsulfonic acid, 2-hydroxy-3 (prop-2-enoyloxy) propane-1-sulfonic acid, 2-hydroxy-3 - [(meth) acryloyloxy] propane-1-sulfonic acid, 3-allyloxy-2-hydroxypropane-1-sulfonic acid, styrene-3-sulfone acid, 3- (meth) allyloxybenzene-1-sulfonic acid, α-methylstyrenesulfonic acid, α-ethylstyrenesulfonic acid, allyloxybenzenesulfonic acid, (meth) allyloxybenzenesulfonic acid, maleic acid bis (3-sulfopryl) ester, maleic acid bis (2 -sulfoethyl) ester, itaconic acid bis (3-sulfopropyl) ester, itaconic acid bis (2-sulfoethyl) ester, 2-propene-1-sulfonic acid, 2-methyl-2-propene-1-sulfonic acid, 4-vinylphe - Nylsulfonsäure and salts of the aforementioned acids and mixtures of the aforementioned monomers, and at least one further ethylenic u saturated monomer selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, itaconic acid and salts of the aforementioned acids and mixtures of the aforementioned monomers are constructed.

7. The method according to any one of claims 1 to 6, wherein the polyacid II contains monomer units from at least one allylic monomer containing at least one sulfonic acid group or a salt thereof, selected from the group consisting of 3-allyloxy-2-hydroxy propane 1-sulfonic acid, 3- (meth) allyloxybenzene-1-sulfonic acid, allyloxybenzenesulfonic acid,

(Meth) allyloxybenzenesulfonic acid, 2-propene-1-sulfonic acid, 2-methyl-2-propene-1-sulfonic acid and salts of the abovementioned acids and mixtures of the abovementioned monomers, and optionally at least one further ethylenically unsaturated monomer selected from the group consisting from acrylic acid, methacrylic acid, maleic acid, itaconic acid and salts of the aforementioned acids and mixtures of the abovementioned monomers.

8. The method according to any one of claims 1 to 7, wherein the polyacid II contains monomer units which are composed of the ethylenically unsaturated monomers acrylic acid, methacrylic acid and 2-methyl-2-propene-1-sulfonic acid or the corresponding salts.

9. A process according to any one of claims 1 to 8, wherein the additive containing a polyoxyalkylene group in options (a) and (b) is selected from the group consisting of (C6-C22) -alcohol ethoxylates, (C6-C22) - Alcohol ether sulfonates and (C6-C22) alcohol ether sulfates, and in option (c) as a polyoxyethylenated ethylenically unsaturated monomer is copolymerized.

10. A redispersible dispersion powder obtainable by the process according to any one of claims 1 to 9.

1 1. Aqueous dispersion obtainable after step (1) of the method according to any one of claims 1 or 3 to 9.

12. containing building material composition the redispersible dispersion powder according to claim 10, and / or

the aqueous dispersion according to claim 11.

13. Use of the redispersible dispersion powder according to claim 10 in a building composition.

14. Use of the aqueous dispersion according to claim 1 1 for the preparation of a redispersible dispersion powder.