Water-resistant polymeric emulsions

Claim 1

A polymeric emulsion comprising (i) a polymer, (ii) water, and (iii) a surfactant, wherein the emulsion comprises less than about 1 weight percent surfactant and at least about 40 percent total solids, and the polymer has an average particle size of about 85 to about 200 nm and a T g of about 0° to about 20° C. and comprises: (a) a soft monomer whose homopolymer has a T g of less than about -20° C., the soft monomer being selected from the group consisting of non-functional acrylic monomers, non-functional methacrylic monomers, ethylene, and mixtures thereof; (b) a hard monomer whose homopolymer has a t g of greater than about 30° C., the hard monomer being selected from the group consisting of alkenyl aromatic monomers, non-functional methacrylic monomers, and mixtures thereof; (c) about 1 to about 5 weight percent of an olefinic carboxylic acid monomer; and (d) about 0.5 to about 5 weight percent of a cross-linking monomer selected from the group consisting of N-methylol acrylamide, N-methylol methacrylamide, diacrylates, dimethacrylates, triallyl cyanurate, diallyl maleate, methyl acrylamidoglycolate methyl ether, olefinically unsaturated monomers having the formula ##STR6## and mixtures thereof, R 1 being selected from the group consisting of hydrogen and halogen, R 2 being selected from the group consisting of hydrogen, halo, thio, and monovalent organic radicals, R 3 being a divalent radical, and Z being selected from the group consisting of organoacyl and cyano, wherein the weight ratio of the hard monomer to the soft monomer in the polymer is about 1:1 to about 1.5:1, the combined weight percent of hard and soft monomers present in the polymer is at least about 90 weight percent, the soft non-functional acrylic and methacrylic monomers have the formula ##STR7## R 5 being selected from the group consisting of hydrogen and methyl and R 6 being an alkyl group containing up to about 15 carbon atoms, and the hard non-functional methacrylic monomers have the formula ##STR8## wherein R 7 is an alkyl group that preferably contains up to about 6 carbon atoms.