Filament yam production

Figure 22.1.21. H S and CS2 removal in the filament yam production (After reference 34).

Figure 11.1 gives a schematic view of both staple fibre and filament yam production. 

Table 11.2 Emission and consumption data for viscose filament yam production [37, CIRFS,2004]...

A feed roU appHes tension to the bundle of fibers to withdraw them from the extmsion cabinet. The product of one extmsion position is caUed a continuous-filament yam, as distinguished from staple. CeUulose acetate yams are generaUy produced in a weight range of 5—100 tex (45—900 den). 

Only a smaU quantity of triacetate yam is made by wet extmsion because extmsion speeds are much lower than for dry extmsion and the process is not attractive for producing filament yams. Melt extmsion is only used for the production of a smaU quantity of triacetate yam. 

From 1910 onward waste filament yam had been chopped into short lengths suitable for use on the machinery designed to process cotton and wool staples into spun yams. In the 1930s new plants were built specifically to supply the staple fiber markets. During World War II the production of staple matched that of filament, and by 1950, staple viscose was the most important product. The new spun-yam oudets spawned a series of viscose developments aimed at matching the characteristics of wool and cotton more closely. Viscose rayon was, after all, silk-like. Compared with wool it lacked bulk, residence, and abrasion resistance. Compared to cotton, it was weaker, tended to shrink and crease more easily, and had a rather lean, limp hand. 

Approximately 2.5 million t of viscose process regenerated ceUulose fibers were produced in 1990 (Table 1). Measured by production capacity in 1990, the leading producers of filament yams in 1990 were the Soviet Union state-owned factories (255,000 t capacity) and Akzo Fibres in Europe (100,000 t). The leading producers of staple fiber and tow were Courtaulds with 180,000 t capacity spUt between the UK and North America Formosa Chemicals and Fibres Co. with 150,000 t in Taiwan Tenzing with 125,000 t in Austria, and a 40% stake in South Pacific Viscose s 37,000 t Indonesian plant and Grasim Industries in India (125,000 t). BASF s U.S. capacity of 50,000 t was acquired by Tenzing in 1992. 

The high speed continuous filament process (69) was first used for manufacturing in 1974, and this enabled the yam production rates to be raised from 150 to 380 m /min. This system uses a pair of net conveyor belts to protect and transport an overfed warp of yams through washing and drying. 

Spinnerette Process. The basic spinning process is similar to the production of continuous filament yams and utilizes similar extmder conditions for a given polymer (17). Fibers are formed as the molten polymer exits the >100 tiny holes (ca 0.2 mm) of each spinnerette where it is quenched by chilled air. Because a key objective of the process is to produce a relatively wide (eg, 3 m) web, individual spinnerettes are placed side by side in order that sufficient fibers be generated across the width. This entire grouping of spinnerettes is often called a block or bank, and in commercial production it is common for two or more blocks to be used in tandem in order to increase the coverage and uniformity of laydown of the fibers in the web. 

The polyamide copolymer of dodecanoic acid with methylenedi(cyclohexylamine) (MDCHA, PACM) was sold as continuous filament yam fiber under the tradename QIANA. As late as 1981, over 145,000 t was produced using high percentages, typically 80%, of trans, trans MDCHA isomer. The low melting raffinate coproduct left after t,t isomer separation by fractional crystallisation was phosgenated to produce a Hquid aUphatic diisocyanate marketed by Du Pont as Hylene W. Upon terrnination of their QIANA commitment, Du Pont sold the urethane intermediate product rights to Mobay, who now markets the 20% trans, trans—50% cis, trans—30% cis, cis diisocyanate isomer mixture as Desmodur W. In addition to its use in polyamides and as an isocyanate precursor, methylenedi (cyclohexyl amine) is used directiy as an epoxy curative. The Hquid diamine mixture identified historically as PACM-20 is marketed as AMICURE PACM by Anchor Chemical for performance epoxies. 

Other Fiber Deformations. Deformations such as bending, torsion, shear, and compression are of practical importance in textile apphcations. Bending and twisting of yams, both influential in the development of bulk and stretch in filament yams, are also important in the production of staple yams. Bending characteristics are important in cmsh resistance in carpets. Bending and shear are factors that influence the hand and drape of apparel fabrics, whereas compression influences the recovery of fabrics after such processes as winding. 

The manufacturing processes for textile filament, staple and industrial filament yams have become so specialized that it is not possible to make one such class of fibers on the others equipment. Within these classes, there are production machines specialized for certain types of fibers for specific types of consumer products. Large machines designed to produce high volumes of commodity products (e.g. staple for cotton blending) at high efficiency and low cost are not well suited to the efficient production of specialty staple variants (e.g. fibers with special dyeing properties) and vice-versa. 

The production figures of PP show impressive growth. The volume, which was less than 10 million lb in 1965, reached over 1.5 billion lb in 1990. This included approximately 17 percent filament yam, 23 percent staple fiber, 18 percent spunbonded fabrics, and 38 percent split film products. 

Microdenier Fibers. The first commercial production of microfiber in the United States was in 1989 by the DuPont Company. Today microfibers are produced in a variety of synthetic fibers (i.e., polyester, nylon, acrylic, etc.) A microfiber is a fiber that is less than one denier per filament. Yams made from microdenier filaments are able to give silklike hand to fabrics. 

About half of the fibrous poly(olefin) textile products are produced in the form of strips, split fibers or monofilaments, another third as staple fibers and the rest as filament yams and textile composites. All poly(olefins) are characterized by excellent resistance to acids, alkalis and other chemicals. Due to this lack of affinity, on the other hand, all poly(olefin) fibers can only be colored by means of melt pigmentation [81]. ... 

As for viscose fibres, these are mostly produced as staple fibres for textile and nonwoven applications. In 2011, world production was 3.246 million tons [49] while filament yam for textile and technical applications reached 332 000 tons in 2011 [49] with a share of technical yarns of 56 000 tons. Technical viscose fibres, also called rayon or viscose rayon, are used mainly as carcass reinforcing fibres in fast-running and run-flat tyres. Lyocell fibres are produced only as staple and virtually exclusively by Lenzing AG, Austria, with a production capacity of 140 000 tons in 2011 [50]. 

In the production of viscose filament yam a Supersorbon -system combined with a NaOH-scmbber system (Figure 22.1.21) has been in use since 1997. A very high standard of safety engineering is implemented in the treatment system owing to the flammability of the CS2 and the toxic nature of the constituents to be removed from the exhaust air. 

---