| 摘要 |
Stretch oriented continuous filaments are produced by melt spinning a linear essentially unbranched, head-to-tail poly alpha-butene having a degree of crystallinity of from 55 to 85% or a mixture of such a polymer and a linear essentially unbranched head-to-tail polypropylene having a degree of crystallinity of from 55 to 85%. The polybutene preferably has an average molecular weight of 100,000 to 300,000 and the proportion of crystalline polymer is preferably 60 to 85%. The degree of crystallinity is determined by X-ray analysis. The filaments may be stretched to an extent such that their length after stretching is 3 to 6 times their length before stretching. The polymers are preferably melt spun at 190 to 250 DEG C. and, quenched in a bath at 30 to 100 DEG C. and then stretched. The polymers may be pigmented and advantageously contain an antioxidant and/or an additive which reduces degradation of the polymer when heated. A list of suitable antioxidants and heat stabilizers is given. Crystalline poly alpha-butene may be obtained by extraction of the crude polymer with n-hexane, the crystalline polymer being the residue from the extraction. In an example, unbranched poly alpha-butene having a crystallinity of 79%, a molecular weight of 190,000 and an intrinsic viscosity of 3,1, to which has been added 0,5% of p-phenylene diamine as an antioxidant, is melt spun at 230 DEG C. through a multi-hole spinneret, the filaments passed through water at 60 DEG C. and stretched by means of a series of rolls to 600 times their original length. The filaments of the invention have good tensile strength combined with chemical inertness, resistance to insects, moulds and bacteria and to both fresh and sea water. Specification 828,791 also is referred to.
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