Verfahren zum Herstellen von Faeden aus Polypropylen

摘要

1303159 Producing polypropylene filaments BADISCHE ANILIN & SODA FABRIK AG 3 April 1970 [5 April 1969] 15892/70 Addition to 1303151 Heading B5B Polypropylene is extruded at a melt temperature of 180 to 360‹ C. to form filaments each having a cross-sectional area of from 0À05 to 0À000375 mm2, and the filaments are drawn at a draw ratio of from 3:1 to 15:1 preferably 4:1 to 11:1 at a temperature which is between 10‹ C. and the crystallite melting point of the polypropylene used to form filaments having a cross-sectional area of from 0À005 to 0À000125 mm.2. The latter is a blend of 70 to 80% by weight of a polypropylene of which less than 1% by weight is soluble in toluene boiling at standard pressure, the ratio by weight of polypropylene to toluene being 5:95, and 20 to 30% by weight of a polypropylene of which more than 99% by weight is soluble in toluene boiling at standard pressure, the ratio by weight of polypropylene to toluene being 5:95. The two polypropylenes have substantially the same intrinsic viscosity and substantially the same molecular weight distribution (determined by the method of gel permeation chromatography). The absolute values of the intrinsic viscosities [#] (measured in decahydronaphthalene at 130‹ C.) of the two polypropylenes are always within the range of from 1 to 10, and preferably within the range of from 1À2 to 3À8. In the example, a mixture of 75% by weight of an insoluble polypropylene having an intrinsic viscosity of 1À6 and 25% by weight of a soluble polypropylene having an intrinsic viscosity of 1À7 are homogenied with each other in an extruder at 220‹ C. to produce a mixture having a crystallite melting point of about 160‹ C. and the mixture is extruded at a melt temperature of 280‹ C. to form filaments each having a cross-sectional area of 0À0122 mm.2 and the filaments are drawn at a draw ratio of 6:1 and a temperature of 150‹ C.; the crosssectional area of each filament is thereby reduced to 0À00187 mm.2 (equivalent to 15 denier.)