Patent ID: 6414085
Filing Date: 2002-07-02
Classification: C08G

Abstract:
A process for the catalyst-free preparation of terephthalate-based unsaturated polyester resins, said process comprising reacting:A) a saturated dicarboxylic acid component comprising minimally 75 mol percent of saturated aromatic dicarboxylic acids or esterifiable or transesterifiable derivatives thereof, terephthalic acid or an esterifiable or transesterifiable derivative thereof comprising minimally 25 mol percent of said saturated dicarboxylic acid component; B) at least one unsaturated dicarboxylic acid or esterifiable or transesterifiable derivative thereof; and C) a glycol component containing at least 65 mol percent 2-methyl-1,3-propane diol based on total mol of glycol, at a temperature in excess of 200Â° C. with an inert gas sparge at a flow rate effective to remove water of esterification, the ratio of (A+B) to (C) such that an unsaturated polyester is obtained having a weight average molecular weight Mw greater than 300 Da, said reacting taking place in the absence of a catalytically effective amount of a metal esterification catalyst; and optionally, D) adding one or more unsaturated vinyl monomers.