Polyesters and their use in compostable products such as disposable diapers

Claim 1

A fiber and film forming polyester consisting essentially of recurring structural units of the formulae: --[--C(O)--R--C(O)--OGO--].sub.a --[--C(O)--Q--O--].sub.b -- wherein about 0.1 to about 2.5 mole % of R is an alkali metal or alkaline earth metal salt of a 4-sulfophthalic radical, up to about 40 mole % of R is a radical D, in amount d, selected from the group consisting of a chemical bond and one or more divalent, non-aromatic, C 1 -C 10 hydrocarbylene radicals, and the remainder of R is a divalent aromatic radical, with at least about 85 mole % of said remainder being p-phenylene, wherein up to about 30 mole % of G is a polyethylene ether radical E, in amount 4e, selected from the group consisting of --(CH.sub.2).sub.2 --O--(CH.sub.2).sub.2 -- and --(CH.sub.2).sub.2 --O--(CH.sub.2).sub.2 --O--(CH.sub.2).sub.2 --, and the remainder of G is selected from the group consisting of hydrocarbylene radicals --(CH 2 ) 2 --, --(CH 2 ) 3 --, and --(CH 2 ) 4 --, and wherein the structural units of the formula: [--C(O)--R--C(O)--OGO--].sub.a contain a total amount of radicals D and/or E that is at least S, wherein S is the total of d+e, where d is the mole % of radical D and e is one quarter of the mole % of radical E, and wherein S is at least 5 mole %, wherein Q is derived from an hydroxy acid of formula HO[--C(O)--Q--O--].sub.x H, where Q is selected from the group consisting of a chemical bond and hydrocarbylene radicals --(CH 2 ) n --(where n is an integer from 1 to 5), --C(R')H--, and --C(R')HCH 2 --, wherein R' is selected from the group of --CH 3 and --CH 2 CH 3 , and where x and Q are selected such that the hydroxy acid has a melting point at least 5 degrees C below its decomposition temperature, and wherein "a⃡ and "b" are mole fractions of the polymer, and the mole fraction "a" is 0.6 to 1 and, correspondingly, mole fraction "b" is 0 to 0.4.