Textured polyethylene terephthalate yarns

Abstract

Textile articles comprise continuous filament yarns (or staple fibers obtained therefrom) of polyethylene terephthalate or another thermoplastic material, in which the individual filaments are of alternately decreasing and increasing thickness, the thinnest zones having the highest crystallinity index and molecular orientation and vice versa, but all the zones having a certain index of crystallinity, each filament having a non-spiral three dimensional crimp and a high apparent volume. The yarns are made by partially stretching the initial yarn in a crack or figure promoting agent, and relaxing the stretched yarn in two or more stages, in at least the last of which it is heated, preferably with a high temperature-time gradient. CROSS REFERENCE TO RELATED APPLICATIONS

What is claimed is: 
     
       1. Textile articles comprising multi-filament polyethylene terephthalate yarns, in which each filament consists of alternating zones whose diameter progressively increases and decreases respectively between at least two different mean values, the parts of lowest diameter having the highest crystallinity index and molecular orientation, the crystallinity index in the thinner parts of the filaments being between 15 and 60 percent and that in the thicker parts being between 5 and 25 percent but always lower than that in the thinner parts, each filament having a non-spiral three-dimensional structure and a high apparent volume. 
     
     
       2. Textile articles according to claim 1, in the form of continuous multifilament yarns.