Polypropylenfasern

摘要

Process for the production of polypropylene fibers from polypropylene polymers produced by the polymerization of polypropylene in the presence of a metallocene catalyst characterized by a bridged racemic bis(indenyl) ligand substituted at the proximal position. The polypropylene contains 0.5 to 2% 2,1 insertions and has a isotacticity of at least 95% meso diads and is heated to a molten state and extended to form a fiber preform. The preform is subjected to spinning at a spinning speed of at least 500 meters per minutes and subsequent drawing at a speed of at least 1,500 meters per minute to provide a draw ratio of at least 3 to produce a continuous polypropylene fiber. The draw speed and/or the draw ratio can be varied to produce fibers of different mechanical properties. Different polypropylene polymers produced by different metallocene catalysts can be used. Such fibers can be characterized by having an elongation at break of at least 100% and a specific toughness of at least 0.5 grams per denier.