Abstract:
Manufacturing a spun-dyed para-aramid filament yarn includes (a) preparing a spin dope comprising a para-aramid polymer, at least one dyestuff and concentrated sulfuric acid, (b) spinning the spin dope through a spinneret to obtain spun filaments, (c) coagulating the spun filaments to obtain coagulated filaments, (d) neutralizing the coagulated filaments to obtain neutralized filaments, (e) washing the neutralized filaments to obtain washed filaments, and (f) drying the washed filaments to obtain dried filaments. In step a) the spin dope includes 17.5 to 18.5% by weight of a para-aramid polymer with respect to the weight of the spin dope, and 4 to 15% by weight of the at least one dyestuff with respect to the weight of the para-aramid polymer plus the at least one dyestuff. In step f) the filaments are hold under a tension in a range from 0.2 to 0.8 cN/dtex.
Abstract:
A pitch precursor yarn, which is stretch broken and formed into a fabric or felt which is heat treated into graphitic fiber media for fuel cell gas diffusion layer substrates and high thermal conductivity reinforced composites.
Abstract:
A pitch precursor yarn, which is stretch broken and formed into a fabric or felt which is heat treated into graphitic fiber media for fuel cell gas diffusion layer substrates and high thermal conductivity reinforced composites.
Abstract:
A method for stretch breaking fibers to produce a staple yarn and operating a staple fiber spinning machine that enables the production of a plurality of products of lot size smaller than a large denier tow product. The process includes at least two break zones and a consolidation zone downstream from a second break zone to form a staple yarn. The filaments are broken in a second break zone downstream from the first break zone by increasing the speed of the fiber fed into the process. The yarn includes discontinuous and, optionally, continuous filaments.
Abstract:
An apparatus and method for stretch breaking fibers wherein the formation of relatively small (lengths less than 30 microns) fractured fibers is substantially reduced. This reduction is achieved by applying a dampening fluid to the bundle of fibers during stretch breaking to dampen shockwaves generated during the fracturing process. The fractured fiber bundle may be subsequently treated with a sizing material to improve bundle cohesiveness and handling characteristics.
Abstract:
A continuous process of making a blended yarn of staple fiber and long-fiber or filamentary material in which the long-fiber or filamentary material is passed through a rupture zone to produce lengths thereof which are fed directly into an air stream with the staple fibers to produce an intimate blend which is conveyed by the air stream directly to an open end spinning device which produces the yarn.
Abstract:
High-shrinkage stretch-broken tows of acrylonitrile polymers are obtained by fixing with saturated steam at maximum temperatures of 140.degree. C. after drawing and before stretch breaking and stretch breaking at a draft of at least 30%.
Abstract:
A method for converting a multifilament bundle of a synthetic material into a sliver and an apparatus for effecting the method. The apparatus comprises: a feed roller device for feeding the bundle; a draft roller device consisting of a pair of draft rollers, the peripheral speed of which draft roller device is higher than that of the feed roller device, for stretch breaking the filaments in the bundle between the feed roller device and the draft roller device; and an apron belt, belted between one roller of the draft roller device and the intermediate portion of the feed roller device and the draft roller device, which is wound around the other draft roller. The broken filaments are smoothed between the apron belt and the other draft roller so that the evenness of the sliver thickness is improved and the uniformity in quality of the spun yarn obtained from the sliver is also improved. Accordingly, the method and apparatus has advantages when a multifilament bundle of a synthetic material is converted into a sliver at a high speed of not less than 200 m/min.
Abstract:
In accordance with the invention, the breaking and stretching machines have pressure heads, each one being essentially constituted by two opposed complexes, upper and lower, each one of which includes at least two transmission chains of the Renold type which are meshed with two chain pinions (double, triple, etc) fitted on two strong parallel shafts that are supported by appropriate bearings attached to the lateral elements of the machine bedplate; those corresponding to the lower complex are fixed, while those corresponding to the upper complex are moveable, so that the latter complex may adopt, with respect to the other complex, two limiting positions; one of separation, which permits the introduction of the layer of fibres, and the other, where the elements approach one another, to be utilized during the work and in which the pressure can be adjusted.