US 4,975,326 AGranted

High strength polyester yarn for improved fatigue resistance

AssigneeAllied-Signal Inc.

InventorsEdward J. Buyalos, David W. Millure, James G. Neal, Hugh H. Rowan

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Abstract

High strength polyester multifilament yarn of improved dimensional stability, which has the proper combination of an intrinsic viscosity of at least 0.90, relatively low work loss and a high degree of toughness, is incorporated as tire cord into a rubber tire for reinforcement to provide an important improvement in fatigue life and retained fatigue strength. The continuous melt-spin process comprises the steps of feeding prepolymer to a first finisher vessel to achieve at least 0.4 intrinsic viscosity transferring polymer to a second finisher vessel for a period sufficient to achieve an intrinsic viscosity of at least 0.95, and supplying this polymer to an extrusion spinnerette.

Claims2

Dependent claims

A high performance polyester multifilament yarn made by a continuous polymerization and melt-spun process and comprising at least 90 mol percent polyethylene terephthalate having the following combination of characteristics:

(a) an intrinsic viscosity of at least 0.90,
(b) a load at 5 percent elongation of at least 3.7 g/d at 25.degree. C.,
(c) a tenacity of at least 7.5 grams per denier at 25.degree. C.,
(d) a shrinkage of less than 8 percent in air at 177.degree. C.,
(e) a work loss of less than 0.04 inch-pounds when cycled between a stress of 0.6 gram per denier and 0.05 gram per denier at 150.degree. C. measured at a constant strain rate of 0.5 inch per minute in a 10-inch length of yarn normalized to that of a multifilament yarn of 1000 total denier,
(f) a toughness of at least 0.40 grams per denier, said yarn providing enhanced fatigue resistance when incorporated as fibrous reinforcement into rubber tires.

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Dependencies are inferred from the claim text.