Epoxy-catalyst additive system to produce higher I.V. polybutylene terephthalate from low I.V. polymer

摘要

The present invention provides a process for preparing branched chain, thermoplastic polymers having improved melt strength and die swell properties. This process comprises reacting at least one thermoplastic polymer capable of reaction with an epoxy functionality, with at least one epoxy branching agent containing at least two epoxy groups per molecule of epoxy branching agent in the molten state, in the presence of a catalytic amount of at least one catalyst. The catalyst may be selected from the group consisting of alkyl triphenyl phosphonium halide and alkenyl triphenyl phosphonium halide wherein the alkyl groups contain from one to ten carbon atoms, the alkenyl groups contain from two to six carbon atoms, and the halide anion is selected from the group consisting of chloride and bromide.PPThe molten, thermoplastic, branched chain polymer reaction product has increased melt strength and intrinsic viscosity. When polyesters or polymers containing carboxylic acid functional groups are reacted with the epoxy branching agent, the improved polymers have a decreased number of carboxylic acid end groups. The increased melt strength polymers also have improved die swell characteristics and are useful in extrusion applications such as blow molding.