Patent ID: 8415433

Claim:
A process for producing hydrophilic polymer microparticles by inverse phase suspension polymerization of a vinyl-based monomer, the inverse phase suspension polymerization of the vinyl-based monomer being carried out using as a dispersion stabilizer a macromonomer having a radically polymerizable unsaturated group at a terminus of a vinyl-based monomer-derived polymer, wherein the macromonomer contains a hydrophobic vinyl-based monomer-derived constituent unit and a hydrophilic vinyl-based monomer-derived constituent unit, wherein at least some of the hydrophobic vinyl-based monomer-derived constituent units are derived from an 8 or more carbons alkyl ester of (meth)acrylic acid, wherein at least some of the hydrophilic vinyl-based monomer-derived constituent units are derived from a carboxy group-containing vinyl monomer, and wherein at least some of the vinyl-based monomer used in the inverse phase suspension polymerization is at least one type selected from (meth)acrylic acid and (meth)acrylamido-2-methylpropanesulfonic acid.