Process for promoting the low temperature cure of polyester resins

This invention relates to an improved three component promoter for enhancing the cure rate of a molding compound comprising an unsaturated polyester resin and an unsaturated monomer copolymerizable therewith. The presence of the three component promoter system substantially enhances the cure rate of the molding compound while at the same time substantially lengthening the shelf life of the prepromoted resin. The three component system comprises a cobalt salt in the plus 2 valence state with the cobalt being present in an amount to provide from about 0.0005-0.06 parts cobalt metal per 100 parts unsaturated polyester resin (including unsaturated monomer), a copper salt, the salt being present in an amount to provide from 0.01-1x10-6 parts copper metal per 100 parts of unsaturated polyester resin (including unsaturated monomer), and an amine selected from the group consisting of tertiary amino alkyl acrylates and methacrylates, heterocyclic amines, para substituted aromatic amines and lower alkyl and alkanol amines (C1-C6) and phenolic amines, the amine being present in an amount to provide from about 0.0001 to 0.05 moles per 100 parts of unsaturated polyester resin, including unsaturated monomer.