Mitsubishi Chemical Corporation

Minako Akita

Tomohiko Tanaka

Michiaki Fuji

The problem to be solved by the present invention is to provide a polycarbonate copolymer containing a plant-derived raw material, which is excellent in the mechanical strength and heat-resistant and assured of small refractive index, large Abbe number, small birefringence and excellent transparency. The present invention provides a polycarbonate copolymer containing a constitutional unit derived from a dihydroxy compound represented by the following formula (1) and a constitutional unit derived from an alicyclic dihydroxy compound, wherein the Abbe number is 50 or more and the 5% thermal reduction temperature is 340&#xb0; C. or more; and a method of producing this polycarbonate copolymer by reacting a dihydroxy compound represented by the following formula (1) and an alicyclic hydroxy compound with a carbonic acid diester in the presence of a polymerization catalyst. 

Polycarbonate copolymer and method of producing the same

A subject for the invention relates to processes for producing a polycarbonate containing a plant-derived starting material and to molded articles thereof, the polycarbonate having excellent mechanical strength, heat resistance, a low refractive index, a large Abbe number, low birefringence, and excellent transparency. The invention relates to a process for producing a polycarbonate which includes a step in which one or more dihydroxy compounds including a dihydroxy compound having at least one linking group &#x2014;CH&#x2014;O&#x2014; in the molecule thereof are reacted with a carbonic acid diester in the presence of a polymerization catalyst, wherein the dihydroxy compound having at least one linking group &#x2014;CH&#x2014;O&#x2014; in the molecule thereof has a formic acid content lower than 20 ppm. The invention further relates to a molded article constituted of a polycarbonate or a composition of the polycarbonate, the polycarbonate being a polycarbonate which contains constituent units derived from a dihydroxy compound having at least one linking group &#x2014;CH&#x2014;O&#x2014; in the molecule thereof and has an Abbe number of 50 or larger and a 5% weight loss temperature of 340&#xb0; C. or higher.

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Mie, Japan

Minako Akita