Process for the preparation of a redispersible dispersion powder composition

A process for the preparation of a dispersion powder composition which is redispersible in water and is based on at least one water-insoluble film-forming organopolymer, said organopolymer being selected from the group consisting of:

• (a) vinyl ester homo- or copolymers containing at least one monomer unit selected from the group consisting of vinyl esters of unbranched or branched alkylcarboxylic acids having 1 to 15 C atoms;
• (b) (meth)acrylic acid ester homo- or copolymers containing at least one monomer unit selected from the group consisting of methacrylic acid esters and acrylic acid esters of alcohols having 1 to 10 C atoms;
• (c) homo- or copolymers of fumaric and/or maleic acid mono- or diesters of unbranched or branched alcohols having 1 to 12 C atoms;
• (d) homo- or copolymers of dienes, and of olefins;
• (e) homo- or copolymers of vinyl aromatics;
• and
• (f) homo- or copolymers of vinyl-halogen compounds;
• wherein the powder composition comprises 0.1 to 30% by weight, based on the organopolymer content, of at least one water-dispersible silicon compound having a boiling point under normal pressure of >160° C. and selected from the group consisting of carbosilanes, carbosiloxanes, tetraorganosilanes, silicic acid esters Si(OR′)4, organoorganoxysilanes, SiRn(OR′)4−n where n=1 to 3, polysilanes of the formula R3Si(SiR2)nSiR3, where n=0 to 8 and oligosiloxanes of the formula R3SiO(SiR2O)nSiR3, where n=0 to 4 in which R′ represents identical or different alkyl radicals or alkoxyalkylene radicals having 1 to 4 C atoms, and R is identical or different, substituted or unsubstituted and denotes branched or unbranched alkyl radicals having 1 to 22 C atoms, cycloalkyl radicals having 3 to 10 C atoms, aryl, aralkyl or alkylaryl radicals having 6 to 18 C atoms, or halogens, ether, thio-ether, ester, amide, nitrile, hydroxyl, amine, carboxyl, sulfonic acid, carboxylic acid anhydride and carbonyl groups, and in which, in the case of the polysilanes and oligosiloxanes, R can also have the meaning OR′, said process consisting of spray drying (1) a dispersion of the organopolymer and optionally auxiliary compounds and (2) an emulsion or dispersion of the silicon compound and optionally, auxiliary compounds, through separate nozzles and drying together in a spay tower.