Redispersible powders comprising pozzolanic components

1. A water-redispersible polymer powder composition comprising at least one homopolymer or copolymer of at least one monomer selected from the group consisting of vinyl esters of optionally or branched alkylcarboxylic acids having from 1 to 15 carbon atoms, (meth)acrylic esters of alcohols having from 1 to 15 carbon atoms, vinylaromatics, olefins, dienes and vinyl halides; one or more protective colloids, optionally one or more antiblocking agents; and at least one pozzolana compound selected from the group consisting of pumice, trass, Santorin earth, hornstones, chert, moler earth, ground brick, fly ash, oil shale ash and calcined kaolin.

2. The water-redispersible polymer powder composition of claim 1 , wherein pozzolana(s) are present in an amount of from 10 -30% by weight relative to the total weight of the polymer powder composition.

3. A water-redispersible polymer powder composition comprising at least one homopolymer or copolymer of at least one monomer selected from the group consisting of vinyl esters of optionally or branched alkylcarboxylic acids having from 1 to 15 carbon atoms, acrylic esters of alcohols having from 1 to 15 carbon atoms, vinylaromatics, olefins, dienes and vinyl halides; one or more protective colloids, optionally one or more antiblocking agents; and at least one pozzolana compound, wherein metakaolin is present as a pozzolana.

4. The water-redispersible polymer powder composition as claimed in claim 1 , wherein said homopolymers or copolymers 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 esters, copolymers of vinyl acetate with ethylene and vinyl chloride, styrene-acrylic ester copolymers, or styrene-1,3-butadiene copolymers.

5. The water-redispersible polymer powder composition of claim 1 , wherein at least one protective colloids is a partially hydrolyzed or fully hydrolyzed, optionally hydrophobically modified, polyvinyl alcohol having a degree of hydrolysis of from 80 to 100 mol % and a Höppler viscosity in 4% strength aqueous solution of from 1 to 30 mPas (Höppler method at 20° C., DIN 53015).

6. The water-redispersible polymer powder composition of claim 1 , wherein the pozzolana is present in an amount of from 5 to 50% by weight, based on the total weight of the powder composition.

7. A process for producing a water-redispersible polymer powder composition comprising a water-redispersible polymer powder composition comprising at least one homopolymer or copolymer of at least one monomer selected from the group consisting of vinyl esters of optionally or branched alkylcarboxylic acids having from 1 to 15 carbon atoms, (meth)acrylic esters of alcohols having from 1 to 15 carbon atoms, vinylaromatics, olefins, dienes and vinyl halides; one or more protective colloids, optionally one or more antiblocking agents; and at least one pozzolana compound, which comprises adding at least one pozzolana compound to a dispersion of the homopolymer or copolymer before drying, atomizing at least one pozzolana compound together with the polymer dispersion during drying, or adding at least one pozzolana compound to the polymer powder after drying.

8. The process of claim 7 , wherein said pozzolana serves as an antiblocking agent, and no further antiblocking agent is added to the water-redispersible polymer powder composition.

9. In a chemical building product, comprising a hydraulically setting binder and a redispersible polymer powder, the improvement comprising including as said redispersible polymer powder, the redispersible polymer powder of claim 1 .

10. The building product of claim 9 , selected from the group consisting of building adhesives, tile adhesives, full thermal insulation adhesives, plasters, renders, knifing fillers, flooring screeds, self-leveling compositions, sealing slurries, jointing mortars, and paints.