GB1024039A - Polyester resins - Google Patents

Abstract

A curable polyester mixture comprises a mixture of an unsaturated polyester containing ether groups and carboxyl groups which is the reaction product of an a ,b -unsaturated dicarboxylic acid component with a polyhydric alcohol component which contains from 10 to 100 mols. per cent based on the amount of said component, of a polyhydric alcohol containing oxygen-ether bridges, which polyester has an acid number of between 5 and 75, with 10 to 100% by weight, calculated on the amount of unsaturated polyester, of magnesium oxide and 1 to 6% by weight, calculated on the amount of unsaturated polyester of an organic peroxide having a decomposition half-life period at 100 DEG C. of at least 10 hours, there being no polymerizable monovinyl compound present. A polyester resin may be made from the curable mixture by heating to a temperature of 130 DEG to 200 DEG C. Additional ether oxygen atoms may be introduced into the unsaturated polyesters by condensation of dicarboxylic acids which contain ether groups, e.g. diglycollic acid; g ,g 1-dipropyl ether dicarboxylic acid and alkoxy-succinic acids. To increase the impact strength of the finished resin, longchained unsaturated ether dicarboxylic acids may be condensed with the above unsaturated polyesters. In the examples the polyesters in the curable mixtures are formed from (1) diglycol, glycol and maleic anhydride; (2) 1,3-butylene glycol, diglycol, anthracene and fumaric acid; (3) dipropylene glycol and fumaric acid; (4) triethylene glycol and maleic anhydride; (5) o ,o 1-dihydroxydibutyl ether and fumaric acid, and (6) b ,b 1-di -(b -hydroxyethoxy)-butane and fumaric acid. Sheets may be formed from the compositions and fillers added before curing.