Method for making stable, homogeneous melt solutions

Abstract

Stable, homogeneous melt solutions are prepared at temperatures of 200 DEG C or less from solid mixtures comprising at least one diaryl carbonate, at least one high melting dihydroxy aromatic compound (mp>200 DEG C), a transesterification catalyst, and optionally a lower melting dihydroxy aromatic compound. Thus, a stable, homogeneous melt solution is obtained from a solid mixture comprising 4,4'-biphenol(mp 282-284 DEG C) at a temperature of about 200 DEG C using either diphenyl carbonate or bis(methyl salicyl) carbonate as the diaryl carbonate component. It is shown that formation of the stable, homogeneous melt solutions requires the presence of the transesterification catalyst when substantial amounts of the high melting dihydroxy aromatic compound are present in the initial solid mixture. Solid mixtures comprising a variety of high melting bisphenols; 4,4'-biphenol; 3,3,3,3'tetramethylspirobiindanbisphenol, and 4,4'-sulfonydiphenol are converted to stable, homogeneousmelt solutions at 200 DEG C, a temperature substantially below the melting points of the high melting bisphenols in their pure states.

Description

Background technique [0001] The present invention relates to the preparation of stable, homogeneous melt solutions useful for the preparation of homopolycarbonates and copolycarbonates. [0002] Polycarbonate is widely used because of its combination of transparency, toughness, heat resistance, and plasticity. It is regarded as a relatively low-cost thermoplastic rate. The most widely used polycarbonate is bisphenol A polycarbonate, with hundreds of millions of pounds of bisphenol A polycarbonate produced and sold worldwide each year. [0003] Polycarbonates, both homopolycarbonates and copolycarbonates, can be advantageously prepared in the absence of solvents, a process sometimes referred to as heating diaryl carbonate in the molten state in the presence of a transesterification catalyst. "melt method" of base esters and one or more bisphenols. This melt method offers certain advantages over the widely used interfacial method of polycarbonate preparation using a solvent, t...

AI Technical Summary

Problems solved by technology

Dichloromethane is a low-boiling chlorinated hydrocarbon and its application requires costly engineering measures to prevent its accidental release into the environment

This poses less difficulty but can pose serious engineering challenges when the diaryl carbonate and dihydroxyaromatic compound have a low melting point, where the melting point of the diaryl carbonate or dihydroxyaromatic compound exceeds 200°C

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