Filament production

Its early commercial success owed much to the flammabUity disadvantages of the Chardoimet process, but competition from the viscose process led to its decline for aU but the finest filament products. The process is stiU used, most notably by Asahi in Japan where sales of artificial sHk and medical disposable fabrics provide a worthwhile income. However, its relatively high cost, associated with the cotton fiber starting point, prevented it from reaching the large scale of manufacture achieved by the viscose rayon process. 

Jets for continuous filament textile yam are typically 1 cm diameter gold—platinum ahoy stmctures with 20—500 holes of 50—200 p.m diameter. Tire yam jets are also 1 cm in diameter but typicahy use 1000—2000 holes to give the required balance of filament and yam denier. Staple fiber jets can have as many as 70,000 holes and can be made from a single dome of ahoy or from clusters of the smaller textile or tire yam jets. The precious metal ahoy is one of the few materials that can resist the harsh chemical environment of a rayon machine and yet be ductile enough to be perforated with precision. Glass jets have been used for filament production, and tantalum metal is a low cost but less durable alternative to gold—platinum. 

Relative scales of the spinning processes for staple and filament products are depicted in Table 12.1. The industrial filament process is intermediate to the staple and textile filament processes, in terms of both spinning throughput and fiber orientation uniformity (here measured by spun birefringence level). Industrial yarns must be uniform enough to be drawn to much higher tenacity levels than staple yams, but are not dyed and therefore not subject to the more demanding uniformity requirements of textile yams. 

The key to the extremely high activity for filament production found with FeO may well reside in the defect structure of this compound. In such a structure the oxygen atoms in the surface will be readily accessible to extraction by protons generated by the hydrocarbon decomposition reaction and as a result the oxide could rapidly attain at the surface an iron rich sponge-like arrangement i.e. the role of FeO is that of a precursor for a high surface area Fe catalyst formed ln-sltu. 

A frozen SPI filament product, with fiber-like texture, was sold in the United States for improving textural characteristics of fabricated foods, including structuring mechanically deboned meat and poultry. The manufacturer s specifications for the product include >93% protein (N x 6.25, mfb), <0.2% crude fiber, 65% moisture, 0.9% ash, and <0.1% fat. 

Polyolefin fibers include polyethylene fiber and polypropylene fiber. About 95VO of polyolefin fibers is polypropylene fiber. Filament products include single filament and spun-bonded non-woven fabrics. 

In gel spinning, extrusion spinning, or gel-extrusion spinning, 35-55% solutions are used. The resulting filaments have a greater dimensional stability because of their lower solvent content, so that the rates of filament production can be greater ( 500 m/min). Polyfacrylonitrile) and poly(vinyl alcohol) are spun by this method. 

Hausen BM, Krohn K, Budianto E (1990) Contact allergy due to colophony. VII. Sensitizing studies with oxidation products of abietic and related acids. Contact Dermatitis 23 352-358 Heino T, Haapa K, Manelius F (1996) Contact sensitization to organosilane solution in glass filament production. Contact Dermatitis 34 294... 

Toffoletto F, Cortona G, Feltrin G, Baj A, Goggi E, Cecchetti R (1994) Occupational contact dermatitis from amine-functional methoxysilane in continuous-glass-filament production. Contact Dermatitis 31 320-321 Toome BK (1989) Allergic contact dermatitis to a nasal cannula. Arch Dermatol 125 571... 

Heino T, Haapa K, Manelius F (1996) Contact sensitization to organosilane solution in glass filament production. Contact Dermatitis 34 294... 

Other authors have reported sensitization from amine functional methoxysilane [(vinylbenzylaminoethyl) amino) propyltrimethoxysilane] in workers at continuous-glass-filament production. 

Figure 1 Process steps, downstream processes and main applications for PP fiber and filament production.

Metal-fiUed polymeric filaments. In the filament production process metal flakes or metal powders are added. 

Carbon aUotropes as the conductive agent such as for carbon fibers, or when in the synthetic polymeric filament production step conductive particles such as carbon black, graphite, graphene, or carbon nanotubes are used. 

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