Hybrid power transmission cord

摘要

A heat-treated cord comprising a low modulus yarn core that is wrapped by a plurality of high modulus wrapping yarns that were heat-treated for a time at a temperature and under a load sufficient to provide a free shrinkage of at least 2½ percent and a shrinkage force of at least 3 pounds.

主权项

1. A method of making a heat-treated hybrid cord, comprising:
providing at least one core yarn having a Young's modulus; and providing a plurality of wrapping yarns, each wrapping yarn having a strength of at least 2.5 GPa and a Young's modulus that is at least 5 GPa greater than the Young's modulus of the at least one core yarn; and pre-twisting the wrapping yarns in a first direction with a twist multiplier in the range of about 2 to about 6½; and twisting the pre-twisted wrapping yarns and the core yarn in the opposite direction with a twist multiplier in the range of about 2 to about 6½ to form a greige hybrid cord; and then heat-treating the greige hybrid cord for a time at a temperature and under a load sufficient to accomplish any one of or both of:
(a) provide a free shrinkage of at least 2½ percent; and/or(b) provide a shrinkage force of at least 3 pounds; and wherein the wrapping yarns in the greige hybrid cord have an untwisted yarn length that is about 0.8% to about 5% greater than the untwisted yarn length of the at last one core yarn in the hybrid cord.