Abstract: The invention provides a process for water-proofing gypsum materials which comprises adding, to a pulverulent gypsum plaster composition containing from 10 to 90% by weight of gypsum based on the total weight of the composition, a mixture ofa) from 1.0 to 15% by weight, based on the total weight of the composition, of one or more dispersion powders redispersible in water and based on vinyl acetate copolymers with ethylene and/or vinyl esters of C.sub.5 -C.sub.15 -monocarboxylic acids, styrene copolymers with acrylic esters of alcohols having from 1 to 18 carbon atoms, vinyl chloride copolymers with ethylene and/or vinyl esters of C.sub.2 -C.sub.15 monocarboxylic acids, andb) from 0.05 to 5.0% by weight, based on the total weight of the composition, of one or more thixotropic additives from the group consisting of polyacrylic acids and their salts, smectites, bentonites, carboxymethylcelluloses and melamine-formaldehyde condensates.

Abstract: A process for the production of a pulverulent, tricklable mixture of ethylene/vinyl acetate copolymer and polyvinylchloride comprising the steps of mixing a mixture consisting essentially of (a) an ethylene/vinyl acetate copolymer having an acetate content of from 15% to 75% by weight, (b) powdery polyvinylchloride, in a mixture ratio of (a) to (b) of 1:3 to 2:1, and (c) from 0 to 5% by weight of the mixture of additives customary for polymer processing, in a high-speed mixture at temperatures above the softening temperature of said polyvinylchloride and below 170.degree. C., for a time sufficient to effect homogenization, quenching said homogenized mixture with water and removing the water, grinding the quenched product with the addition of from 0.5 to 10 parts by weight of an inert powder having particles in the submicroscopic range, in a high speed mill under passage of an airstream which is heated by friction, and recovering said pulverulent, tricklable mixture; as well as the powdery mixture so produced.