# US 5,702,828 A · Process for waterproofing gypsum materials > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,702,828 A - Document ID: US5702828A - Status: Granted - Kind: A - Application number: 08/605,615 - Filed: 1996-02-22 - Granted: 1997-12-30 - Earliest claimed: 1995-02-23 - Assignees: Wacker Chemie AG - Inventors: Klaus Adler; Erwin Gubisch; Alois Sommerauer - Web page: https://patentgrep.com/patent/US5702828A ## CPC - C04B 24/26: obtained by reactions only involving carbon-to-carbon unsaturated bonds {(C04B24/243 takes precedence)} - C04B 28/14: containing calcium sulfate cements {(gypsum-paper plates E04C)} - C04B 2111/27: Water resistance, i.e. waterproof or water-repellent materials - Y10T 428/4935: Impregnated naturally solid product [e.g., leather, stone, etc.] - C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## 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 of a) 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, and b) 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. ## Claims ### Claim 1 A process for waterproofing gypsum materials which comprises adding, to a pulverulent gypsum plaster composition containing from 10 to 90% by weight of gypsum based on the total composition weight of the composition, a mixture of a) from 1.0 to 15.0% 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, and b) from 0.05 to 5.0% by weight, based on the total weight of the composition, of at least one thixotropic additive selected from the group consisting of polyacrylic acids and their salts, smectites, bentonites, carboxymethylcelluloses, and melamine-formaldehyde condensates. ### Claim 2 (depends on 1) The process as claimed in claim 1, wherein the polymers redispersible in water are based on vinyl acetate-ethylene copolymers containing from 20 to 50% by weight of ethylene units, vinyl acetate copolymers containing from 1 to 40% by weight of vinyl laurate units and from 50 to 95% by weight of units of vinyl esters of .alpha.-branched C.sub.5 -C.sub.10 monocarboxylic acids, and also, if desired, from 5 to 40% by weight of ethylene units, or vinyl acetate copolymers containing from 70 to 95% by weight of vinyl laurate units or units of vinyl esters of .alpha.-branched C.sub.5 -C.sub.10 -monocarboxylic acids (Versatic acid.sup.R vinyl ester); styrene copolymers containing from 40 to 60% by weight of n-butyl acrylate and/or 2-ethylhexyl acrylate units, vinyl chloride-ethylene copolymers having an ethylene content of from 10 to 40% by weight, vinyl chloride copolymers containing from 10 to 40% by weight of ethylene units and from 45 to 40% by weight of vinyl laurate units or units of vinyl esters of .alpha.-branched C.sub.5 -C.sub.10 monocarboxylic acids. ### Claim 3 (depends on 1) The process as claimed in claim 1, wherein the polymers redispersible in water are based on vinyl acetate copolymers containing from 1 to 40% by weight of vinyl laurate units and from 1 to 30% by weight of units of vinyl esters of .alpha.-branched C.sub.9 -C.sub.10 monocarboxylic acids, vinyl acetate copolymers containing from 70 to 95% by weight of units of vinyl esters of .alpha.-branched C.sub.9 -C.sub.10 monocarboxylic acids, vinyl chloride copolymers containing from 10 to 40% by weight of ethylene units and from 5 to 40% by weight of vinyl laurate units. ### Claim 4 (depends on 1) The process as claimed in claim 1 wherein the thixotropic additives used are selected from the group consisting of high molecular weight homopolymers and copolymers of acrylic acid, their alkali metal and ammonium salts; water-swellable sheet silicates, organically modified smectites, bentonites (aluminum sheet silicates), montmorillonites; carboxymethylcelluloses; and water-soluble melamine-formaldehyde condensates. ### Claim 5 (depends on 1) The process as claimed in claim 1 wherein the thixotropic additives used are organically modified smectites and bentonites. ### Claim 6 (depends on 1) The process as claimed in claim 1 wherein the gypsum plaster used is .alpha.- .beta.-hemihydrate (CaSO.sub.4.1/2H.sub.2 O), flooring plaster, Keene's cement, anhydrite or calcium sulfate formed in flue gas desulfurization. ### Claim 7 (depends on 1) The process as claimed in claim 1 wherein the components a) and b) are mixed and homogenized together with the gypsum plaster and additional constituents or additives. ### Claim 8 (depends on 2) The process as claimed in claim 2 wherein the vinyl acetate copolymers containing from 1 to 40% by weight of vinyl laurate units and from 50 to 95% by weight of units of vinyl esters of .alpha.-branched C.sub.5 -C.sub.10 monocarboxylic acids also contain from 5 to 40% by weight of ethylene units. ### Claim 9 A process for waterproofing gypsum materials which comprises adding to said materials a mixture of: a) 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 -mono-carboxylic acids, styrene copolymers with acrylic acid 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, and b) one or more thixotropic additives selected from the group consisting of polyacrylic acids and their salts, smectites, bentonites, carboxymethylcelluloses and melamine-formaldehyde condensates. ### Claim 10 (depends on 9) The waterproof gypsum materials prepared by the process of claim 9. ### Claim 11 (depends on 9) In a process for the application of stucco plaster to an exterior surface which is exposed to the weather, the improvement which comprises applying to said surface a stucco plaster which contains the mixture of claim 9. ### Claim 12 (depends on 9) In a process for the production of plasterboards or plaster molds from a gypsum plaster composition, the improvement which comprises adding to said compositions the mixture of claim 9.