Abstract: An improved two-stage process for the preparation of polyester resins is provided which involves an initial reaction of a dicarboxylic acid such as isophthalic acid with an alkylene oxide such as ethylene or propylene oxide in the presence of a catalyst to form an oligoester reaction mixture, followed by a second stage reaction between the oligoester reaction mixture and a dibasic acid or anhydride; a first-stage catalyst is employed which has a thermal decomposition temperature substantially at or below the second-stage reaction temperature. The most preferred first-stage catalyst is benzyltriethylammonium chloride.
Type:
Grant
Filed:
June 18, 1997
Date of Patent:
March 9, 1999
Assignee:
Cook Composites & Polymers Co.
Inventors:
Chih-Pin Hsu, Ming-Yang Zhao, L. Scott Crump