Polyesters and their use in compostable products such as disposable diapers

A fiber and film forming biodegradable polyester which undergoes hydrolytic degradation when subjected to the conditions of moisture and temperature that typically characterize composting operations to form products readily digested to innocuous materials by organisms typically found in solid waste and compost, said polyester consisting essentially of recurring structural units of the formula:

• --[--C(O)--R--C(O)--OGO--].sub.a --[--C(O)--Q--O--].sub.b --
• wherein about 5 to 40 mole % of R is selected from the group consisting of a chemical bond and one or more divalent, non-aromatic, C.sub.1 -C.sub.10 hydrocarbylene radicals, and at least about 85 mole % of the remainder of R is p-phenylene radical,
• wherein G is about 1 to 30 mole % of a polyethylene ether radical 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 a hydrocarbylene radical selected from the group consisting of
• --(CH.sub.2).sub.2 --, --(CH.sub.2).sub.3 --, and --(CH.sub.2).sub.4 -radicals,
• wherein Q is derived from an hydroxy acid of formula
• HO[--CO(O)--Q--O--].sub.x H,
• where x is an integer, such hydroxy acid having a melting point at least 5 degrees C. below its decomposition temperature, and Q is selected from the group consisting of a chemical bond and hydrocarbylene radicals --(CH.sub.2).sub.n --, where n is an integer from 1 to 5, --C(R')H--, and --C(R')HCH.sub.2 --, wherein R' is selected from the group of --CH.sub.3 and --CH.sub.2 CH.sub.3, and
• wherein "a" and "b" are mole fractions of the polyester, and the mole fraction "a" may be 0.6 to 1 and, correspondingly, mole fraction "b" may be 0 to 0.4, and
• wherein about 0.1 to about 2.5 mole % of the polyester is composed of moieties comprising alkali metal or alkaline earth metal sulfo groups.