Novel process for deep stretch forming of polyesters

Claim 1

A biaxially oriented, hermetically sealable, hollow container prepared from high molecular weight polyester, said polyester being a saturated linear polyester derived from C 6 to C 10 aromatic dicarboxylic acids or the lower C 1 to C 4 dialkyl ester reactive equivalents and polyalkylene glycols of the general formula HO(CH 2 ) n OH where n is an integer ranging from 2 to 10, said polyester having an intrinsic viscosity ranging from about 0.5 to about 1.1 as measured in a 60/40 by volume mixed solvent of phenol and tetrachloroethane at 30° C., and a density of about 1.361 grams per cubic centimeter or less wherein the ratio of the weight in grams of the polyester to the inside volume of the container in cubic centimeters ranges from about 0.1:1.0 to about 0.01:1.0, a Gardner impact strength of at least 100 in-lbf, a volume shrinkage of 3.0 percent or less when subjected to temperatures ranging from about 90° C. to about 110° C., and a density ranging from about 1.364 to about 1.400 grams per cubic centimeter, said container made by stretching said polyester from about 4.0 to about 6.0 times in the axial direction and from about 2.0 to about 3.0 times in the hoop direction, and said container being stretched with a plunger, said plunger temperature ranging from about 60° C. to about 100° C. and said container being heat set.