PURPOSE: To obtain the subject resin having properties of less foaming, coloring and generating odor, by continuously polymerizing methyl methacrylate in a solution in the presence of a specific radical polymerization initiator and a specific chain transfer agent under specific conditions in respect to their concentrations in complete mixing vessels of two-step connected in a series.
CONSTITUTION: By using complete mixing vessels of two-step connected in a series, methyl methacrylate alone or a composition containing 71-95wt.% of a monomer mixture consisting of 75wt.% or more of methyl methacrylate and 25wt.% or less of a 1-4C, alkylacrylate, and 29-5wt.% of a solvent, is adjusted to have a polymerization initiator concentration of 5.0×10-4-1.2 mole % and a chain transfer agent concentration of 1.0×10-3-1.0 mole %, and continuously polymerized at a polymerization temperature in first vessel of 100-170°C, and in second vessel of 130-170°C, with an average retention time set at 5-7000 fold of a half life of the polymerization initiator, by keeping a polymerization efficiency of 70-90%, to obtain a resin having 5% or less of a DW value before a history of after treatment, expressed by the formula [DW is decreasing weight ratio (wt.%); γWi is a content of a polymer having a double bond in its chain end in the i-th vessel (wt.%); RAi is a concentration of acrylate (mole %); and ΔMi is a concentration of consumed monomer in the i-th vessel].
FUJITA ROKURO
KUROKAWA MASAHIRO
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