Novel copolyesters and their use in compostable products such as disposable diapers
AssigneeE. I. Du Pont de Nemours and Company
InventorRaymond F. Tietz
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Abstract
The invention provides novel copolyesters, fibers and films, nonwovens from the fibers and disposable products of the copolyesters such as diapers. The products are degradable under the conditions typically existing in waste composting processes, have low ingredient costs and yet provide strength and toughness properties adequate for end uses such as in disposable diapers. The copolyesters are based upon polyethylene terephthalate copolymerized with a 5-sulfoisophthalic acid and, if desired, a polyethylene ether, such as diethylene glycol, and include units from hydroxyacids selected for their melting points being lower than their decomposition temperatures.
Claims13
A fiber and film forming copolyester consisting essentially of recurring structural units (1) of the formula
- --C(O)--R--C(O)--OGO--
- in amount about 60-98% by weight,
- wherein R is about 97 to 99.9 mole % para-phenylene
- and about 0.1 to 2.5 mole % of the sulfonate radical ##STR4## where M is an alkali metal or alkaline earth metal, and wherein G is about 60 to 80 mole % --CH.sub.2 --CH.sub.2 -- and
- about 20 to 40 mole % --(CH.sub.2).sub.2 --O--(CH.sub.2).sub.2 --, and
- about 2 to 40% by weight of the copolyester being structural units (2) of the formula [--C(O)--Q--O--].sub.n, wherein n and Q is such that the hydroxyacid HO--C(O)--Q--OH and/or the polyhydroxyacid HO[--C(O)--Q--O--].sub.n H has a melting point at least 5.degree. C. lower than its decomposition temperature.
Dependencies are inferred from the claim text.