Patent ID: 6362273
Filing Date: 2002-03-26
Classification: C08F,C08G

Abstract:
Aqueous polymer dispersion containing a water-dispersed polyurethane polymer and a vinyl polymer in a weight ratio of from 30/70 to 5/95, wherein said polyurethane polymer is the reaction product of:A) an isocyanate-terminated polyurethane prepolymer having an acid value of &gE;44 mg KOH/g of prepolymer (solids) and is formed from reactants comprising an organic polyisocyanate component and an organic poly(isocyanate-reactive group) component in which the isocyanate-reactive groups are selected from â€”OH and optionally one or more of â€”NH2â€”, â€”NHâ€”, and â€”SH, wherein i) at least 70 weight % of said polyisocyanate component is constituted by at least one aliphatic polyisocyanate, ii) said poly(isocyanate-reactive group) component includes at least one acid bearing poly(isocyanate-reactive group) compound for providing anionic groups which provide or contribute to water-dispersibility, iii) the reactants are used in amounts corresponding to a ratio of isocyanate groups to isocyanate-reactive groups within the range of 1.4/1 to 2.9/1; and B) an active hydrogen chain-extending compound(s), and wherein said vinyl polymer is derived from one or more monomers selected from the group consisting of esters of acrylic acid and methacrylic acid of formula CH2&boxH;CR2COOR3 â€ƒwherein R2 is H or methyl and R3 is alkyl or cycloalkyl of 1 to 20 carbon atoms, 1,3-butadiene, isoprene, styrene, &agr;-methyl styrene, divinyl benzene, acrylonitrile, methacrylonitrile, vinyl halides, vinyl esters, alkyl esters of mono-olefinically unsaturated dicarboxylic acids, hydroxyalkyl(meth)acrylates, and olefinically unsaturated monocarboxylic and/or dicarboxylic acids.