Production of thermally stabilized polyester

Claim 2

A thermally stabilized high molecular weight linear terephthalate condensation polyester having incorporated therein a thermally stabilizing amount of a stabilizer consisting of an epoxy compound having 5 to 25 carbon atoms in the molecule and selected from the group having the formula ##STR8## where R represents the radical remaining after removal of the carboxyl group from a monocarboxylic acid, R 1 , R 2 , and R 3 represent hydrogen or hydrocarbon radicals, and n is an integer that can be 0 to 3, said thermally stabilized polyester having a free carboxyl concentration of less than 15 gram equivalents of carboxyl groups per 10 6 grams of polyester.

Claim 3

The polyester of claim 1 wherein the linear terephthalate condensation polyester is polyethylene terephthalate.

Claim 4

The polyester of claim 1 wherein 5 to 70 gram mols of said epoxy compound is incorporated per 10 6 grams of the polyester.

Claim 5

The polyester of claim 1 wherein 10 to 50 gram mols of said epoxy compound is incorporated per 10 6 grams of the polyester.

Claim 6

The polyester of claim 1 additionally containing a catalytic amount of 4-dimethylaminopyridine.

Claim 7

In a process for the preparation of a high molecular weight linear terephthalate condensation polyester wherein terephthalic acid is reacted with a glycol containing 2 to 10 carbon atoms per molecule under esterification conditions and the resulting esterification product is polycondensed, the improvement which comprises providing a reduction in the free carboxyl content of the polyester to a carboxyl concentration of less than 15 gram equivalents per 10 6 grams of polyester by adding to the polyester after final polycondensation of the polyester a thermally stabilizing amount of a stabilizer comprising an epoxy compound having 5 to 25 carbon atoms in the molecule and selected from the group having the formula ##STR9## where R represents the radical remaining after removal of the carboxyl group from a monocarboxylic acid, R 1 , R 2 , and R 3 represent hydrogen or hydrocarbon radicals, and n is an integer from 0 to 3.

Claim 8

In a process for the preparation of a high molecular weight linear terephthalate condensation polyester wherein terephthalic acid is reacted with a glycol containing 2 to 10 carbon atoms per molecule under esterification conditions and the resulting esterification product is polycondensed, the improvement which comprises providing a reduction in the free carboxyl content of the polyester to a carboxyl concentration of less than 15 gram equivalents per 10 6 grams of polyester by adding to the polyester after final polycondensation of the polyester a thermally stabilizing amount of a stabilizer comprising an epoxy compound having 5 to 25 carbon atoms in the molecule and selected from the group having the formula ##STR9## where R represents the radical remaining after removal of the carboxyl group from a monocarboxylic acid, R 1 , R 2 , and R 3 represent hydrogen or hydrocarbon radicals, and n is an integer from 0 to 3.

Claim 9

The process of claim 6 wherein the linear terephthalate condensation polyester is polyethylene terephthalate.

Claim 10

The process of claim 6 wherein 5 to 70 moles of said epoxy compound is incorporated per 10 6 grams of the polyester.

Claim 11

The polyester of claim 6 wherein 10 to 50 gram moles of said epoxy compound is incorporated per 10 6 grams of the polyester.

Claim 12

The process of claim 6 wherein said epoxy compound is added to the polyester together with a catalytic amount of 4-dimethylaminopyridine.

Claim 13

In the preparation of tire yarn from a linear polyethylene terephthalate condensation polyester by melt spinning, the method of providing a reduction in the free carboxyl content of the polyester to a carboxyl concentration of less than 15 gram equivalents per 10 6 grams of polyester which comprises adding to the polyester after final polycondensation of the polyester a thermally stabilizing amount of a stabilizer comprising an epoxy compound having 5 to 25 carbon atoms in the molecule and selected from the group having the formula ##STR10## where R represents the radical remaining after removal of the carboxyl group from a monocarboxylic acid, R 1 , R 2 , and R 3 represent hydrogen or hydrocarbon radicals, and n is an integer from 0 to 3.

Claim 14

In the preparation of tire yarn from a linear polyethylene terephthalate condensation polyester by melt spinning, the method of providing a reduction in the free carboxyl content of the polyester to a carboxyl concentration of less than 15 gram equivalents per 10 6 grams of polyester which comprises adding to the polyester after final polycondensation of the polyester a thermally stabilizing amount of a stabilizer comprising an epoxy compound having 5 to 25 carbon atoms in the molecule and selected from the group having the formula ##STR10## where R represents the radical remaining after removal of the carboxyl group from a monocarboxylic acid, R 1 , R 2 , and R 3 represent hydrogen or hydrocarbon radicals, and n is an integer from 0 to 3.