Patent ID: 6093786
Filing Date: 2000-07-25
Classification: C08G

Abstract:
A process for reducing carbonyl byproduct generation in the condensation polymerization of 1,3-propanediol (emphasis supplied) and an aromatic diacid or alkyl ester thereof to produce an aromatic polyester, the process comprising:adding to a condensation polymerization reaction mixture 1,3-propanediol (emphasis supplied) and an aromatic diacid or alkyl ester thereof:(i) a hindered phenol of the formula ##STR6## in which each R is independently selected from C.sub.1-30 alkyl and at least one R is ortho to the phenolic hydroxyl group; x is an integer from 1 to 4; A is a C.sub.5-50 hydrocarbyl or heterocarbyl group; and n is an integer from 1 to 4; and(ii) an aromatic organophosphite comprising a trivalent phosphorus group (ArO).sub.w P in which Ar is an aromatic group and w is an integer from 1 to 3; andsubjecting said reaction mixture to a temperature within the range of about 180 to about 300.degree. C. for a time sufficient to produce a polyester composition having an intrinsic viscosity of at least about 0.8.