Mitsubishi Gas Chemical Company, Inc.

Mituhiko Masumoto

Shigeo Yanada

Takao Kawaki

Yasuhiko Kijima

Yuh Miyauchi

Toru Nakajima

Satoshi Kanayama

Toshiaki Izumida

Toshiaki Takata

Tadami Kinugawa

Kazuyuki Akahori

Eizi Ukita

A process for producing a dichloroformate of a tetrahalogenated bisphenol by an interfacial process in a high yield and a high content and a process for producing an aromatic copolycarbonate oligomer by a solution process using the resulting dichloroformate monomer are disclosed. The first process comprises adding a catalyst for chloroformate formation to a tetrahalogenated bisphenol in an amount of from 1.times.10.sup.-4 to 1.times.10.sup.-1 mol per mol of the bisphenol and consecutively adding a halogenated carbonyl to effect reaction while controlling the pH of the reaction system between 10 and 12 by consecutive addition of a basic inorganic compound to the reaction system. The copolycarbonate oligomer obtained using the dichloroformate monomer has high alternating regularity.

Process for producing copolycarbonate oligomer from dichloroformate

A process for producing a polycarbonate resin having excellent heat stability from a dihydric phenol compound represented by the formula (1) shown below by an interfacial polymerization method wherein fatty acid represented by the formula (2), (3), (4) or (5) shown below is used as a terminator and as a polymerization catalyst, a quaternary ammonium salt is used, and after 5 to 40 minutes from the addition and emulsification of the polymerization catalyst, tertiary amine is added to cause polymerization. ##STR1## wherein all the symbols are the same as defined before.

Process for producing fatty acid-terminated polycarbonate resin

A resin composition for optics is disclosed, which mainly comprises a graft copolymer comprising a styrene resin and an aromatic polycarbonate each having a specific molecular weight at a specific ratio of molecular weight and weight, said composition having a micro disperse phase of not more than 0.5 .mu.m. The resin composition has a reduced optical strain and an excellent micro disperse phase and is, therefore, suitable for use as optics.

Molding material for optics

A polycarbonate resin having an improved flexibility, flowability and heat resistance, and a process for producing such polycarbonate resins are disclosed. The polycarbonate resin of this invention is particularly useful as optical articles and other precision molding materials and is produced by a solution polymerization method using a bisphenol compound and a substituted alkylenebisphenol compound.

Copolycarbonate resin from branched chain alkylene bis phenol

A transparent optical article is disclosed, which is produced by molding a branched polycarbonate resin having a viscosity average molecular weight of from 13,000 to 20,000 as prepared from at least one dihydric phenol compound in the presence of a polyfunctional organic compound having at least two phenolic hydroxyl groups as a branching agent in an amount of from 0.02 to 3 mol % based on the total amount of the dihydric phenol compound. The transparent molded optical article includes digital audio discs, video discs, memory discs and lenses used in the optical reading system. The optical article is greatly reduced in double refraction and has a high mechanical strength.

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Osaka, Japan

Mituhiko Masumoto