Stretched fluoropolymers

Abstract

The present invention is directed to stretched filaments based on fluoropolymers, where the filaments were stretched at a temperature between 70° C. and the Vicat temperature and where the filaments are cooled under full tensile load to room temperature.

1 . A process for producing stretched filaments comprising at least 80% by weight of at least one fluoropolymer, the process comprising:
 stretching raw filaments with a stretching factor greater than or equal to 3 at a temperature between 70° C. and a Vicat temperature of the at least one fluoropolymer, which is determined in accordance with DIN EN ISO 306:2004-10 B50, and   cooling the raw filaments after stretching under full tensile load to below 50° C.,   wherein the stretched filaments have a rectangular cross section where a thickness thereof is less than a width thereof,   wherein the stretched filaments are made of non-perfluorinated polymers.   
     
     
         2 . The process according to  claim 1 , where the at least one fluoropolymer is selected from the group consisting of polyvinylidene fluoride (PVDF), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (E-CTFE), polychlorotrifluoroethylene (PCTFE), ETFE modified by a tercomponent or modified by vinylidene fluoride, and copolymers based on vinylidene fluoride which comprise up to 40% by weight of other monomers. 
     
     
         3 . The process according to  claim 1 , where the Vicat temperature of the at least one fluoropolymer is at least 80° C. 
     
     
         4 . Stretched filaments produced by the process according to  claim 1 , having a width to thickness ratio of at least 25. 
     
     
         5 . A composite comprising the stretched filaments according to  claim 4 . 
     
     
         6 . A winding layer comprising the stretched filaments according to  claim 4 .