General Electric Company

Satoru Minami

Tomoaki Shimoda

Godavarthi S Varadarajan

Akio Kanezawa

Takato Kimura

Kazutoyo Uno

Takayoshi Anamizu

Kiyoshi Kono

A method for manufacturing polycarbonate by melt-polycondensing bisphenol and carbonic acid diester uses as catalyst an alkali metal compound and/or alkaline earth metal compound (a). The catalyst is added to the bisphenol prior to the melt polycondensation, in an effective amount, i.e., the amount of alkali metal compound and/or alkaline earth metal compound (a) that acts effectively as a catalyst, is contained in said bisphenol, and is controlled to have the same catalytic activity as 1&times;10 to 1&times;10 mole of bisphenol disodium salt per mole of pure bisphenol A. The method conducts the reaction efficiently from the initial stage in a stable manner to obtain polycarbonate with good color, good heat stability and color stability during molding and the like.

Manufacturing method for polycarbonate

The present invention provides a method for manufacturing polycarbonate with excellent dwell stability (e.g., thermal stability and hue stability) during melting and molding, as well as with a low content of impurities. The present invention further relates to a method for manufacturing polycarbonate wherein the molten polycarbonate is filtered through a passivation treated metal filter.

Method for manufacturing polycarbonate

A method for determining the effective level of catalyst for the preparation of a polycarbonate polymer by a transesterification reaction is disclosed. The method involves measurement of the leaving group by-product (usually phenol) produced in a test reaction between an aromatic dihydroxy compound and a carbonic acid diester, in the presence of a known amount of transesterification catalyst. The by-product production values can be compared with by-product reference values to calculate the effective level of catalyst. This data can be used to efficiently control catalytic activity in a production scale reaction for producing polycarbonate polymer.

Method for controlling the effective level of catalyst during the

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Ichihara, Japan

Satoru Minami