Mitsubishi Gas Chemical Company, Inc.

Kohji Yamamoto

Senzo Shimizu

Toshiyuki Abe

Akira Miyamoto

Yasumitsu Higuchi

Fumitaka Satoh

Processes for producing an oligoester and producing unsaturated polyester resin by use of the oligoester using unsaturated dibasic acid or its anhydride and isophthalic acid as dibasic acid components, and propylene oxide as a polyol component, characterized by (a) the step of reacting isophthalic acid with propylene oxide in the presence of an amine compound catalyst to form an oligoester, (b) the step of removing volatile components from the oligoester by heating it at a temperature range of 180.degree.-300.degree. C., (c) the step of treating the resulting oligoester with silica-alumina compound having adsorbing property, and (d) the step of reacting the oligoester so treated with the unsaturated dibasic acid or its anhydride.

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Hiratsuka, Japan

Kohji Yamamoto