Polyamide Filaments and process for making them

摘要

1,150,860. Polyamide filaments and process for making them. E. I. DU PONT DE NEMOURS & CO. 28 Dec., 1967, No. 58847/67. Heading B5B. Crystalline oriented filaments of a polyamide consisting primarily of the following recurring structural units wherein n is 9-14, preferably 10, at least 70% by weight of the diamino constituent of the repeating units being of a trans-trans stereoisomeric configuration, and the filaments having a transverse crystal spacing of 4À3 to 4À7Š, as determined from the strongest equatorial reflections in a Bragg X-ray diffraction pattern may be produced by drawing melt spun filaments of the polymer while they are at a temperature t (‹C.) exceeding 290+S-15 m+20 (- 1)m, where m is the total number of carbon atoms in the aliphatic diacid and S is the trans-trans stereoisomer content of the diamino constituent of the repeating unit in per cent by weight, said temperature being below the softening point of the polymer and preferably not above the viscous flow drawing temperature. The drawing is preferably carried out in two stages, the temperature being higher in the second stage. The second stage drawing is normally part of a drawing process wherein the filaments attain an orientation equivalent to that obtained with at least a 3À5: 1 draw ratio. The melt spinning of the filaments is preferably effected into a heated inert gas such as nitrogen or steam to prevent excessive spinning orientation and render the filaments more highly drawable subsequently. The molecular weight of the polymer is preferably at least 18,000 and more preferably 25,000 to 35,000. The polymer is a polyamide formed by the polycondensation of bis-(4-aminocyclohexyl)- methane and aliphatic diacids of 11 to 16 carbon atoms. Copolymer components, whether the foreign component replaces the amine, the acid or both, should preferably be kept to no more than about 10% by weight (calculated as the weight per 100 grams of polymer of where X refers to the acid entity in the foreign component, Y refers to the amine entity and Z refers to an amino acid component). In an example, a polymer prepared by polycondensation of bis-(4-aminocyclohexyl) methane of 70% trans-trans stereoisomer content and dodecandioic acid, said polymer having a relative viscosity of 115 (measured in 98% formic acid) is melt spun at 295‹ C. and the yarn thereby formed is drawn at a draw ratio of 3À56 over a snubbing pin maintained at 100‹ C. The yarn then travels in a helical wrap around a pipe with a temperature gradient of 150‹ to 190‹ C. (increasing in the direction of yarn travel) to a total draw ratio of 4À0. The yarn is finally further drawn at a draw ratio of 1-49 over a hot pin at 150‹ C. and a 2-zone hot-plate heated to 200‹ and 210‹ C.