General Electric Company

Kazutoyo Uno

Tomoaki Shimoda

Masahide Tanaka

Akio Kanezawa

Hajime Oyoshi

Satoru Minami

Yoshio Motoyama

Michio Tanaka

Kiyoshi Kono

Hideto Matsuoka

Satoshi Inoki

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, which makes it possible to manufacture aromatic carbonates from dialkyl carbonates and aromatic hydroxy compounds inexpensively and with good efficiency. The method uses a titanium catalyst in a particular amount relative to aromatic polyhydric hydroxy compound impurities in a crude aromatic hydroxy compound solution.

Method for manufacturing aromatic carbonates

A manufacturing method for polycarbonate comprising �I! a process for manufacturing diaryl carbonate from an aromatic hydroxy compound and an aromatic hydroxy compound, �II! a process for manufacturing polycarbonate by solution polymerization of the diaryl carbonate obtained in �II! and an aromatic dihydroxy compound in the presence of a catalyst comprising a nitrogen-containing basic compound, and �III! a process for separating and removing the nitrogen-containing compound from the aromatic hydroxy by-products in �II! and returning the resultant aromatic hydroxy compounds to process �I! effectively reuses aromatic hydroxy by-products (e.g., phenols) of polycarbonate manufacturing to manufacture diaryl carbonate, while suppressing the production of alkyl aromatic ethers and then uses this diaryl carbonate to manufacture polycarbonate with good productivity.

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Chiba, Japan

Kazutoyo Uno