| 摘要 |
PROBLEM TO BE SOLVED: To provide foamable methyl methacrylate resin particles having a large particle dia. of about 400μm or more which can be easily impregnated with a foaming agent and is reduced in venting of gases trapped therein. SOLUTION: A preparative process for methyl methacrylate resin particles by suspension-polymerization of a monomer contg. methyl methacrylate as a main component in an aq. medium which is characterized by starting the polymerization in an aq. medium contg. a suspension stabilizer comprising an anionic, water-soluble polymer and a 1-10 wt.% concn., based on the aq. medium, of disodium hydrogen phosphate and by adding a suspension stabilizer comprising a nonionic, water-soluble polymer at a time when the polymerization rate becomes 40-80%, with adding an easily volatile foaming agent during the polymerization and impregnating the resin obtained by the suspension polymerization with the foaming agent. |
