# US 5,705,561 A · Moisture-curable modified acrylic copolymer sealant composition > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,705,561 A - Document ID: US5705561A - Status: Granted - Kind: A - Application number: 08/664,761 - Filed: 1996-06-17 - Granted: 1998-01-06 - Earliest claimed: 1993-12-22 - Assignees: Tremco Incorporated - Inventors: Waldemar E. Kozakiewicz; David K. Potter; Steven A. Young - Web page: https://patentgrep.com/patent/US5705561A ## CPC - C09D 143/04: Homopolymers or copolymers of monomers containing silicon - C08F 220/1804: {C4-(meth)acrylate, e.g. butyl (meth)acrylate, isobutyl (meth)acrylate or tert-butyl (meth)acrylate} - C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D) - C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS ## Abstract A crosslinkable acrylic copolymer sealant composition has a stabilized viscosity in that the viscosity does not unduly increase nor does the material gel on storage for periods of time up to and including one year. The stabilized viscosity is unexpectedly achieved by adding moisture scavengers either before and/or during the polymerization of the various monomers. The sealant composition is suitable for use in high movement applications as well as to metal and glass substrates. ## Claims ### Claim 1 A viscosity stabilized acrylic copolymer composition comprising; the free radical initiated reaction product of at least a) at least one acrylate monomer, methacrylate monomer, or combination thereof, represented by the formula ##STR3## where R' is hydrogen or a methyl group, and R.sup.2 is an alkyl group containing from 2 to about 9 carbon atoms; b) from about 0.05 to about 0.95 molar parts, of at least one silane functionalized addition monomer having at least one hydrolyzable group, said silane functionalized addition monomer having the formula ##STR4## where R" is hydrogen or a methyl group, R.sup.3 is an alkylene group, y is 0 or 1, R.sup.4 is an alkyl group, Z is a hydrolyzable group, and x is 1, 2 or 3 said molar parts being based on 100 molar parts of the at least one acrylate monomer, methacrylate monomer, or combination thereof; c) up to about 60 molar parts by weight of a vinyl addition monomer free of hydrolyzable groups bonded to a silicon atom and being other than an acrylate or methacrylate per 100 molar parts of said at least one acrylate monomer, methacrylate monomer, or a combination thereof; d) up to an amount less than 1 molar part of a mercaptosilane chain transfer agent represented by the formula H--S--R.sup.5 --SiR.sup.6.sub.3-x Z.sub.x where R.sup.5 is an alkylene group, R.sup.6 is an alkyl group, X is 1, 2, or 3 and Z is a hydrolyzable group, wherein said molar part is based upon 100 molar parts of said at least one acrylate monomer, methacrylate monomer or a combination thereof; and e) from about 0.5 to about 4 molar parts of a polyfunctional organosilane moisture scavenger having from 2 to 4 hydrolyzable groups and not being copolymerizable through free radical reactions into said stabilized acrylic polymer said molar parts of said polyfunctional organosilane moisture scavenger being based on molar pairs of silyl groups on said copolymer from said silane functionalized addition monomer and/or said mercaptosilane. ### Claim 2 (depends on 1) An acrylic polymer according to claim 1, wherein said vinyl addition monomer c) comprises a vinyl substituted aromatic monomer, acrylonitrile monomer, methacrylonitrile monomer or combinations thereof. ### Claim 3 (depends on 2) An acrylic polymer according to claim 2, wherein said mercaptosilane is from about 0.05 to about 0.95 molar parts. ### Claim 4 (depends on 1) An acrylic polymer according to claim 1, having a viscosity increase of less than 50% as measured by extrusion through a 6 mm diameter pore upon aging one year at 23.degree. C. ### Claim 5 (depends on 4) An acrylic polymer according to claim 4, wherein said silane functionalized addition monomer comprises a vinyl trialkoxysilane. ### Claim 6 (depends on 3) An acrylic polymer according to claim 3, wherein said silane functionalized addition monomer comprises a vinyl trialkoxysilane. ### Claim 7 (depends on 6) An acrylic polymer according to claim 6, wherein said at least one acrylate monomer, methacrylate monomer or combination thereof consists essentially of butyl acrylate. ### Claim 8 (depends on 1) A sealant formulation comprising an acrylic copolymer composition according to claim 1. ### Claim 9 A process for preparing a moisture curable modified acrylic polymer sealant composition, comprising the steps of; forming an modified acrylic polymer, said polymer derived from the reaction of at least a) at least one acrylate monomer, methacrylate monomer, or combination thereof, represented by the formula ##STR5## where R' is hydrogen or a methyl group, and R.sup.2 is an alkyl group containing from 2 to about 9 carbon atoms; b) from about 0.05 to about 0.95 molar parts, of at least one silane functionalized addition monomer having at least one hydrolyzable group, said silane functionalized addition monomer being represented by the formula ##STR6## where R" is hydrogen or a methyl group, R.sup.3 is an alkylene group, y is 0 or 1, R.sup.4 is an alkyl group, Z is a hydrolyzable group, and x is 1, 2 or 3, said molar parts being per 100 molar parts of the at least one acrylate monomer, methacrylate monomer, or combination thereof; and c) an effective amount of vinyl substituted aromatic monomer, acrylonitrile, methacrylonitrile or combinations thereof to impart improved tensile strength, adding an effective amount of a moisture scavenger prior to completing polymerization, said moisture scavenger having from 2 to 4 hydrolyzable groups and not being free radically copolymerizable into said modified acrylic to said monomers, to stabilize the subsequently formed polymer against a viscosity increase upon exposure to moisture; and subsequently compounding said copolymer with at least one compounding agent. ### Claim 10 (depends on 9) A process according to claim 9, wherein said moisture scavengers are present during the entire polymerization. ### Claim 11 (depends on 9) A process according to claim 9, wherein an effective amount of said moisture scavengers is present before 50 wt. % of said modified acrylic polymer is formed. ### Claim 12 (depends on 9) A process according to claim 9, wherein said silane functionalized addition monomer comprises vinyl trialkoxysilane. ### Claim 13 (depends on 9) A process according to claim 9, wherein said moisture scavenger comprises isobutyltrialkoxysilane. ### Claim 14 (depends on 12) A process according to claim 12, wherein said moisture scavenger comprises isobutyltrialkoxysilane. ### Claim 15 (depends on 9) A process according to claim 9, wherein said at least one acrylate monomer, methacrylate monomer or combinations thereof comprises butyl acrylate. ### Claim 16 (depends on 14) A process according to claim 14, wherein said at least one acrylate monomer, methacrylate monomer or combinations thereof comprises butyl acrylate. ### Claim 17 (depends on 16) A process according to claim 16, wherein said at least one compounding ingredient includes a vinyltrialkoxysilane.