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US 5,705,561 AGranted
Moisture-curable modified acrylic copolymer sealant composition
AssigneeTremco Incorporated
InventorsWaldemar E. Kozakiewicz, David K. Potter, Steven A. Young
Life of this patent
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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.
Claims17
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.
6 more elements
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.
5 more elements
Dependencies are inferred from the claim text.