| 摘要 |
<p>979,083. Crimpable polyolefin filaments. SOC. DE LA VISCOSE SUISSE. Nov. 9, 1962 [Nov. 24, 1961], No. 42392/62. Heading B5B. [Also in Division D1] Spontaneously crimping polyolefin filaments are made by stretching to at least 1.5 times their original length composite filaments composed of two different mutually adherent fibre-forming polyolefin constituents side-by-side along the length of the filaments the two constituents differing in specific viscosity (determined in 0.1% solution in tetrahydronaphthalene at 135‹ C.) by at least 0.1. Specified polyolefins include high-pressure polyethylene, low-pressure polyethylene, and polypropylene. Any process effecting the necessary viscosity difference may be used-e.g. two polyolefines of equal viscosity may be fed into separate melting devices and melted under different conditions. Preferably, the two constituents are simultaneously meltspun using the spinnerets shown. Fig. 1 shows a spinneret for making yarns consisting exclusively of composite filaments, two melts P 1 and P 2 being supplied to the melt-chambers 2 and 3. The resulting filaments are of the " side-by-side " form. Figs. 5 and 6 show a spinneret for making yarns containing both unitary and composite filaments. Two melts P 1 and P 2 are supplied to two differently-shaped melt-chambers 15 and 16. The orifices 17 in the bottom of chamber 15 are equidistant from the partition 21 and spinneret orifices 23, while the orifices 18 in the bottom of the chamber 16 are disposed at different distances from the partition 21 and the spinneret orifices 23. The number of orifices 17 differs from the number of orifices 18. Owing to the different shapes of chambers 15 and 16, of the different distances of the individual orifices 17 and 18 from the partition 21 and the spinneret orifices 23, and of the different numbers of orifices 17 and 18, different pressure conditions are set up immediately in front of the spinneret orifices 23a-23h. Some orifices, e.g. 23a and 23b, are charged exclusively with melt P 1 , and the remainder, e.g. 23c to 23h, with different proportions of the two melts P 1 and P 2 , so that unitary filaments emerge from 23a and 23b, and composite filaments from the remainder, these composite filaments differing from each other in the proportions of the two melts they contain. Either or both components may contain matting agents, pigments, stabilizers or plasticizers. The ratio of unitary to composite filaments can be varied by adjustment of the above variables. Conventional stretching means are used, and the stretched filaments may be allowed to crimp by release of tension, the crimped filaments then being heat-set in the slack state. Alternatively, the spontaneously crimping filaments may be made into yarns with unitary filaments and the yarns then stabilized either by twisting or by heat-setting under tension.</p> |
