Published December 2000
Polycarbonate resins are commercially produced by interfacial and transesterification processes. In the former, bisphenol A (BPA) is phosgenated in an aqueous solution of sodium bisphenolate with methylene chloride as an organic solvent; in the latter process, BPA reacts with diphenyl carbonate (DPC) in a molten state without the solvent. Traditionally, DPC has been prepared by phosgenating phenol. In recent years, however, with nonphosgene technology DPC can be prepared the following phosgene-free processes, which we review in the Report:
- DPC Process 1-DPC from phenol by oxidative carbonylation using fixed-bed reactors
- DPC Process 2-DPC from phenol by oxidative carbonylation using autoclave reactors
- DPC Process 3-DPC from DMC by oxidative carbonylation and conversion of DMC
- DPC Process 4-DPC from phenol by direct phosgenation.
We review these DPC processes, compare their economics, and assess their integration with the melt process. We also present the economics of the following four potentially commercial (PC) polycarbonate processes:
- PC Process 1- Polycarbonate by the interfacial process with on-site phosgene generation
- PC Process 2- Polycarbonate by integrated nonphosgene melt process with DMC and DPC as intermediates
- PC Process 3- An alternative case of PC Process 2 with DMC used as captive feedstock
- PC Process 4- Polycarbonate by the integrated nonphosgene melt process with DPC as an intermediate.
Trends in use during the next 10 years will include the introduction of ultra-pure polycarbonate for enhanced optical requirements for digital video disks and automotive glazing. The challenge for suppliers will be to create resins with lower MW to improve high-flow capabilities while retaining the resinís traditional performance attributes. These requirements make the integrated melt processes more commercially attractive, not to mention their environmentally friendly nature.
World demand for polycarbonate in 1998 was estimated at 1.19 million tons (2.62 billion pounds). The United States, Western Europe, and Japan were the major consumers, accounting for more than 90% of demand. Their market share will fall, however, as demand for polycarbonate increases throughout Asia and Latin America.
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