| 摘要 |
1,246,052. Producing fibrillated polyolefine products. J. P. BEMBERG A.G. 3 Jan., 1969 [3 Jan., 1968], No. 530/69. Heading B5B. In the production of fibrillated polyolefin products by melt-extruding polyolefinic material to form film or film strips, longitudinally orienting the film or the strips at a high draw ratio and fibrillating the oriented product by mechanical treatment, the polyolefinic material comprises polypropylene as the main constituent, the polypropylene comprising 5 to 30% by weight of atactic components, and the minor constituent is low-pressure polyethylene present in a proportion of up to 30% by weight. The polyethylene renders it possible to fibrillate satisfactorily polypropylene films or film strips &c. consisting of polypropylene containing significant proportions of atactic components, which films &c. can otherwise not be fibrillated to obtain usable products. The fibrillation of the film strips &c. may be increased by incorporating in the polymer mixture small proportions of blowing agents which generate gases when the film strip is heated or contacted with water. In the example, 100 parts by weight of polypropylene containing about 20% by weight of atactic polypropylene is mixed with 20% by weight of low-pressure polyethylene and the mixture is melt extruded at 280‹ C, to form a film which is solidified by cooling, and slit longitudinally into strips. The strips are drawn at a draw ratio of 9À5 and fibrillated by twisting to form fibrillated fibres.
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