Resilient organic microspheres in mastic adhesives, sealants, caulks, coating compounds and related products, and methods of manufacture

Process for the preparation of a mastic adhesive composition which comprises subjecting an aqueous slurry of hollow, resilient expandable thermoplastic resinous microspheres formed of an expandable copolymer or vinylidene chloride and acrylonitrile having a diameter of about 6 to 8 microns and having incorporated therein a volatile liquid blowing agent for said thermoplastic resin, to a temperature of about 80.degree. to 140.degree. C. for a period of about 1 to 3 seconds whereby the blowing agent is converted to a gas causing the microspheres to expand, and then quenching to 50.degree. to 65.degree. C. with an aqueous mastic composition to increase the volume and decrease the weight of said adhesive.