Flame retarding polyester composition

Claim 1

A flame retarding thermoplastic polyester composition comprising an admixture of: (A) a thermoplastic polyester comprising a condensation product of an aromatic dicarboxylic acid and an alkanediol, (B) from 3 to 30 parts by weight per 100 parts of the thermoplastic polyester, of a polymeric flame retarding agent having, in the recurring unit, a structure represented by the formula ##STR11## wherein A represents a member selected from the group consisting of an alkylene group having 1 to 6 carbon atoms, an ether, a carbonyl thioether and a sulfone group, said polymeric flame retarding agent having a molecular weight of from about 1000 to 5000, and (C) from 0.05 to 5 parts by weight per 100 parts of the polyester of at least one phosphite compound selected from the group consisting of compounds represented by the general formulas (I) and (II) ##STR12## wherein R is a monovalent alkyl group having 6 to 20 carbon atoms, R' is hydrogen or a monovalent alkyl group having 1 to 6 carbon atoms, η is an integer of 2 to 4, and B represents a member selected from the group consisting of an alkylene group having 1 to 6 carbon atoms, ether, carbonyl, thioether and sulfone groups.