Viscose staple fiber production

General Features of Viscose Staple Fiber Production [89]. Cellulose from wood is the most important starting material for staple fiber production by the visco.se process. Cellulose xanthate is obtained by converting cellulose to sodium cellulose followed by treatment with carbon disulfide. 

Figure 14. Srheinalir of viscose staple fiber production...

New Concept of Waste-Gas Capture during Viscose Staple Fiber Production. As a result of the basic chemical reactions in a sulfuric acid plant and the desired conversion of nearly 100%, the ratio of the quantity of combustion air to sulfur is fixed. If the entire amount of waste gas formed in a conventional viscose staple fiber plant were to be used as combustion air in a sulfuric acid plant, about 30 times as much sulfuric acid would have to be produced as the staple fiber plant consumes. The quantity of lean waste gas from the viscose plant must therefore first be matched to the much lower combustion air requirement of the sulfuric acid plant. This can be achieved by appropriate reduction of the air exhaustion in the viscose staple fiber plant. However, this is possible only if, at the same time, risks to safety as a result of exceeding the in-plant threshold limit value and of the occurrence of explosive gas-air mixtures are avoided. 

Viscose staple fiber production Viscose staple fiber... 

Recovery and Utilization of Residues in the Production of Viscose Staple Fiber... 

Approximately 3 million metric tons of regenerated cellulose fibers production capacity existed in 2000 (Table 2). The leading producers of filament yams were the Chinese state-owned factories (118,000-t capacity), Acordis in Europe (69,0001), and the Russian plants (with 44,000 t). The leading producers of staple fiber and tow were the Chinese with 480,0001, the Birla Group (India) with 408,0001, Lenz-ing (Austria, U.S.A., and Indonesia) with 315,000 t and Acordis with 170,000-t capacity split between the United Kingdom and North America, Formosa Chemicals and Fibers Co. with 162,000 t (in Taiwan). Acordis was formed in 1998 from the fiber businesses of Courtaulds and Akzo-Nobel following the takeover of Cour-taulds by Akzo, who later sold Acordis to a consortium of CVC Partners and Acordis management. (Note since these statistics were compiled, 100,000 ton of Acordis s viscose staple fiber capacity has closed.)... 

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. 

To make a continuous carbon fiber, a continuous viscose rayon fiber is required, which immediately imposes a limitation, since the majority of current viscose production is chopped to form a staple product. A further limitation is that specific end users superimpose their own purchasing specifications, like NASA and the atomic energy industry where, for example, the presence of certain trace elements would have to be rigidly controlled. Availability of suitable... 

Fibers are the basic element of nonwovens world consumption of fibers in nonwoven production is 63% polypropylene, 23% polyester, 8% viscose rayon, 2% acrylic, 1.5% polyamide and 3% other high performance fibers [8]. The data in Fig. 10.4 shows the market share of important polymers and fibers in the nonwovens market. Manufacturers of nonwoven products can make use of almost any kind of fibers. These include traditional textile fibers, as well as recently developed hi-tech fibers. Future advancements will be in bicomponent fibers, micro-fibers (split bicomponent fibers or meltblown nonwovens), nano-fibers, biodegradable fibers, super-absorbent fibers and high performance fibers. The selection of raw fibers, to a considerable degree, determines the properties of the final nonwoven products. The selection of fibers also depends on customer requirement, cost, processability, changes of properties because of web formation and consolidation. The fibers can be in the form of filament, staple fiber or even yam. 

Interest in the manufacture of different forms of rayon has resulted in the production of regular rayon, hollow viscose, spun-dyed filaments and staple rayon, crimped rayon and surface modified fibers, high tenacity rayon and high wet modulus (polynosic) rayon fibers. In chemical composition, viscose rayon and cotton are alike they are both cellulose. 

Greater success was achieved by DuPont who copolymerized, the sodium salt of 5-sulfoisophthalic acid into PET to render the polymer dyeable with cationic (basic) dyes. Basic dyeable PET was successfully launched as Dacron 64 in the form of a low-pill staple product [64]. The presence of the sulfonate groups in the polymer chain also acts as an ionic dipolar cross-link and increases the melt viscosity of the polymer quite markedly. Thus, it is possible to melt-spin polymer with IV 0.56 under normal conditions, giving a low-pill fiber variant. The fiber also has a greater affinity for disperse dyes due to the disruption of the PET structure. Continuing this theme, there are deep dye variant PET fibers, often used in PET carpet yarns, which are copolymers of PET with chain-disrupting copolymer units like polyethylene adipate. They have less crystallinity and a lower Tg. therefore, they may be dyed at the boil without the use of pressure equipment or carrier at the cost of some loss of fiber physical properties. 

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