linear, phosphorus containing copolyester, processes to manufacture and its application as flame retardants.

摘要

A linear copolyester, useful as a flame retardant agent, contains in its macromolecule units deriving from: (a) terephthalic acid; (b) (C2-C6)-alkylene glycol; (c) phenyl-hydroxymethylene phosphinic acid, in a mutual ratio comprised within the range of from 1 : 1 : 0.2 to 1 : 1 : 1, amd is obtained by placing a linear polyester deriving from terephthalic acid and a (C2-C6)-alkylene glycol into contact with a poly(phenylhydroxymethylene phosphinate) (I): CHEM wherein: Ph is the phenyl radical; R is a hydrogen atom or a linear or branched alkyl radical containing from 1 to 8 carbon atoms; and n is a number comprised within the range of from 2.5 to 100, under melting conditions, and for a contact time not longer than about 30 minutes. Such a copolyester contains the (c) units randomly distributed throughout the macromolecular chain, has an amorphous or partially crystalline structure as a function of its content of said (c) unit, and is useful in order to endow the linear polyesters, also in mixture with one another (polymeric alloys), with flameproof characteristics.