Abstract: An emulsion polymerized latex composition suitable for use as a pressure sensitive adhesive having from about 90 to about 99.5 percent by total weight polymer of sec-butyl acrylate and from about 10 to about 0.5 percent by total weight polymer prepared from monomers selected from the group consisting of alkyl esters of acrylic and methacrylic acids wherein the alkyl chain has up to about 20 carbon atoms, monovinylidene aromatics, and ethylenically unsaturated carboxylic acids. Additionally the latex composition can include from about 1 to about 90 percent by weight on a total solids basis of a tackifying resin. Adhesives prepared with the subject latex compositions provide an excellent balance of adhesive properties, i.e., peel and shear adhesion.

Abstract: Expandable synthetic resinous microspheres are expanded in a matrix by heating under pressure to at least a foaming temperature and permitting the microspheres to expand at a lower pressure.

Abstract: Uniformity in the polymerization of expandable microspheres disclosed in U.S. Pat. 3,615,972 is improved by replacing a copolymer of adipic acid and diethanol amine with citric acid.