Multistage heat treating pre-wind synthetic thread to lower shrinkage

摘要

A process for spinning, drawing and winding up a synthetic thread entails subjecting it after drawing but before winding to heat treatment to minimise shrinkage. The thread is passed through several high temperature zones separated from each other at intervals, i.e. is led without touching over a heated surface at a temperature above that at which the thread material melts and at the same time is subjected to tension lower than that needed to plastically deform the material. Also claimed is an apparatus for implementing the process, where thread (1) is pulled from the drawing zone by an unheated galette (54) and then heated on galette by means of apparatus (8) before winding under low tension. The heating apparatus has two galettes (16, 23) with, between them, a lengthwise extended parallel surface (36) heated to temperature as above and over which the thread is led several times as far as possible without touching