Process for preparing polycarbonate and apparatus for preparing polycarbonate

Abstract

A process for preparing an end-capped polycarbonate comprises melt reacting an aromatic dihydroxy compound, a carbonic acid diester, and optionally a catalyst in a prepolymerization vessel 4a / 4b to form a polycarbonate product; transferring the polycarbonate product from the prepolymerization vessel 4a / ab; mixing the polycarbonate product with an end-capping agent under hermetic seal at a pressure of at least about 76 mm Hg; and transferring the polycarbonate product and en-capping agent mixture to a postpolymerization vessel 9 to endcap the polycarbonate product. An apparatus for preparing an end-capped polycarbonate comprises a prepolymerization vessel 4a / 4b having and inlet and an outlet; a postpolymerization vessel 9 having an inlet and an outlet; a mixer in fluid communication with the outlet of the prepolymerization vessel 4a / 4b and the inlet of the postpolymerization vessel 9; and a charging port through which an end-capping agent is charged to the mixer, wherein the mixer is hermetically sealed at greater than or equal to 760 mm Hg.

Description

[0001] Cross-references to related applications [0002] This application is based on and claims the benefit of Japanese Patent Application No. 2001-217251 filed on July 17, 2001, which is incorporated herein by reference. Background of the invention [0003] A method of making polycarbonate and an apparatus used in the method are disclosed therein. [0004] Polycarbonate is widely used due to its outstanding mechanical properties such as impact resistance, heat resistance and transparency. Methods for preparing polycarbonates that are familiar to those skilled in the art include, for example, interfacial and melt methods. In the interfacial method, aromatic diols such as bisphenol A react directly with phosgene. The melt method involves transesterification of an aromatic dihydroxy compound such as bisphenol with diallyl carbonate such as diphenyl carbonate in a molten state. Transesterification is generally preferred because it does not use toxic solvents such as phosgene ...

AI Technical Summary

Problems solved by technology

[0006] However, it should be noted that in the case of the use of end-capping agents, if the polymerization reaction does not proceed to a sufficient extent, the degree of polymerization will not be high enough and low molecular weight polycarbonates and / or polycarbonates with a broad molecular weight distribution will be obtained

In addition, even if the end-capping agent is added after the polycondensation reaction has progressed to the desired point, the end-capping efficiency is still poor

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