Patent ID: 8759410
Filing Date: 2014-06-24
Classification: C08F,C08J

Abstract:
1. A method of producing a thermally foamable microsphere in which a foaming agent is encapsulated in an outer shell, the method comprising: performing suspension polymerization of a mixture of monomers in the presence of the foaming agent in an aqueous dispersion medium containing a dispersion stabilizer and a polymerization aid, wherein the mixture of monomers consists of: wherein the vinyl monomer is one or more of the following (methacrylic) acid ester: a molar ratio of the methacrylonitrile to methacrylic acid in the mixture of the monomers is 1:3 to 3:1; and a proportion of the vinyl monomer is 2 to 10% by weight; wherein the polymerization aid is at least one compound selected from the group consisting of alkali metal nitrite, stannous chloride, stannic chloride, water-soluble ascorbic acids, and boric acids; and wherein the polymerization aid is used in a proportion of 0.001 to 1 part by weight based on 100 parts by weight of the mixture of monomers.