Patent ID: 7252882
Filing Date: 2007-08-07
Classification: B01J,C08J,Y10T

Abstract:
1. A thermally foamed microsphere having structure in which a foaming agent is encapsulated in a shell formed of a polymer, wherein: (1) the shell formed of a polymer is formed of; (a) a vinylidene chloride (co)polymer obtained by polymerization of vinylidene chloride alone or a mixture of vinylidene chloride with a vinyl monomer copolymerizable therewith as a polymerizable monomer, and a bifunctional crosslinkable monomer having two polymerizable carbon-carbon double bonds, or (b) a (meth)acrylonitrile co(polymer) obtained by polymerization of (meth)acrylonitrile alone or a mixture of (meth)acrylonitrile with a vinyl monomer copolymerizable therewith as a polymerizable monomer, and a bifunctional crosslinkable monomer having two polymerizable carbon-carbon double bonds, wherein the bifunctional crosslinkable monomer is a compound having a structure in which two polymerizable carbon-carbon double bonds are linked together via a flexible chain derived from a diol compound selected from the group consisting of polyethylene glycol, polypropylene glycol, an alkyidiol, an alkyl ether diol and an alkyl ester diol, and the bifunctional crosslinkable monomer is used at a proportion of 1.1 to 5% by weight based on the polymerizable monomer, and (2) a maximum expansion ratio of the thermally foamable microsphere is at least 5.