Polycarbonates - Economic aspects

As early as 1898, A. Einhorn experimented with the preparation of polycarbonates, but only obtained a polymer that could not be processed. Between 1953 and 1957, Bayer and General Electric, simultaneously and independently, developed this thermoplastic and introduced it in 1957.

PC polycarbonate can be obtained by two different methods:

• starting with bisphenol A and diphenylcarbonate ;

• using bisphenol A dispersed in alkaline solution and an ammonium salt as catalyst;

  with successive phosgene treatment.

The result is a resin solution that can be processed into powder and granules.

Phosgene is made from CO and Cl ₂ and solvents, water and methylene chloride, the latter suspected of being carcinogenic. Phosgene is toxic, corrosive and highly polluting. Efforts by PC producers have focused on finding phosgene-free processes, since 2000.

PC has benefited from the fact that its specific monomer, bisphenol A, obtained by condensation of two phenol molecules to one acetone molecule, is also used in significant quantities in the manufacture of epoxy resins.

PC is an amorphous thermoplastic.

For further information, please refer to [AM 3381] Polycarbonates.