A NOVEL POLYPROPYLENE FIBER AND A PREPARATION PROCESS THEREOF

摘要

A fiber excellent in strength and having an average size of 10,000 - 0.1 denier can be obtained by extruding a raw material composed mainly of a polypropylene having a syndiotactic pentad fraction of 0.7 or more and optionally stretching the resulting extruded material. By using as the raw material a composition consisting of two kinds of polypropylenes each having an intrinsic viscosity eta 1 or eta 2, the log( eta 2/ eta 1) being more than 0.05 or less than -0.05, and a syndiotactic pentad fraction of 0.7 or more at a weight ratio of 95 : 5 - 5 : 95 or a composition consisting of at least 50 parts by weight of a syndiotactic polypropylene having the intrinsic viscosity eta 1 and a syndiotactic pentad fraction of 0.7 or above and at most 50 parts by weight of an isotactic polypropylene having the intrinsic viscosity eta 2, the extrudability is improved and the fiber stretching conditions are broadened.