Dainippon Ink and Chemicals, Incorporated

Hiroharu Shirota

Motoyasu Kunugiza

Hideyuki Ishizu

Katsuhide Nishimura

A process for producing a polycarbonate polyol by ester-interchange reaction of a dialkyl, diaryl or alkylene carbonate and a polyhydroxy compound, wherein the dialkyl, diaryl or alkylene carbonate is purified by adsorption treatment with an adsorbent prior to use in the reaction. A process for producing a polycarbonate polyol which comprises ester-interchange reaction of a dialkyl or diaryl carbonate and a polyhydroxy compound in the presence of a catalyst, wherein the proportion of the polyhydroxy compound to the dialkyl or diaryl carbonate is 1.01 to 1.30 times its stoichiometrical amount, and the amount of the catalyst is 0.0001 to 0.5% by weight, calculated as metal, based on the dialkyl or diaryl carbonate. Also provided is a process for producing a polycarbonate polyol by ester-interchange reaction of a dialkyl, diaryl or alkylene carbonate and a polyhydroxy compound in the presence of a catalyst in an amount, as metal, of 0.0001 to 0.5% by weight based on the dialkyl, diaryl or alkylene carbonate, which comprises a first step of reacting the dialkyl, diaryl or alkylene carbonate with the polyhydroxy compound, a second step of treating the resulting product with water at 60 to 300.degree. C. to inactivate the catalyst, and a third step of removing water.

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Izumi, Japan

Hiroharu Shirota