Patent ID: 6403728
Filing Date: 2002-06-11
Classification: B29C,C08G,C08J,C08K,C08L

Abstract:
A process for preparing articles from polyester resins comprising the steps of:melt-shaping a resin having an intrinsic viscosity higher than 0.5 dl/g and lower than about 1.0 dl/g, mixed with an upgrading additive selected among the dianhydride of tetacarboxylic acids; and upgrading the shaped article at temperatures higher than 130Â° C. but lower than the resin melting point under vacuum or in an inert gas stream for a time of 4 to 64 hours to raise the resin intrinsic viscosity at least 0.1 dl/g with respect to the value of the intrinsic viscosity of the resin before the upgrading treatment.