Published March 1989
This supplementary report updates PEP Report No. 50B, Polycarbonates (October 1982). It covers progress since then in the technology of manufacturing polycarbonates, modified polycarbonates, and copolycarbonates by the inter-facial or melt (transesterification) processes. In particular, the technologies of polymer recovery from organic solution in the interfacial process and a nonphosgenation process for diphenyl carbonate used in the melt process are discussed.
We evaluate three different routes for polymer recovery in the conventional interfacial process. In addition, we consider an alternate method of recycling a saturated salt solution to the reaction zone. We also evaluate two modified interfacial processes, one for making a cyclic oligomer of bisphenol A carbonate and the other for making solid polycarbonate in situ during the polymerization by reducing the level of methylene chloride in the reaction mixture.
With regard to the melt process, we evaluate a nonphosgenation melt process by replacing the phosgenation of phenol for diphenyl carbonate production in the conventional melt process with nonphosgenation production. For comparison, we also have updated the economic assessment of the conventional melt process, which was presented in our previous report (PEP Report No. 50B).
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