Polyester filaments of high shrinkage and high shrinkage tension may be prepared by heat treatment of undrawn crystalline filaments of low shrinkage and shrinkage tension, and may be used for making polyester yarns of mixed shrinkage and bulky polyester yarns and fabrics therefrom....http://www.google.fr/patents/US5645936?utm_source=gb-gplus-shareBrevet US5645936 - Continuous filaments, yarns, and tows
