Manufacturing process rayon

Schweizer s reagent The dark blue solution obtained by dissolving Cu(OH)2 in concentrated ammonia solution. Used as a solvent for cellulose, the cellulose is precipitated on acidification. Used in the cuprammonium process for the manufacture of rayon. 

Three forms of caustic soda are produced to meet customer needs purified diaphragm caustic (50% Rayon grade), 73% caustic, and anhydrous caustic. Regular 50% caustic from the diaphragm cell process is suitable for most appHcations and accounts for about 85% of the NaOH consumed in the United States. However, it caimot be used in operations such as the manufacture of rayon, the synthesis of alkyl aryl sulfonates, or the production of anhydrous caustic because of the presence of salt, sodium chlorate, and heavy metals. Membrane and mercury cell caustic, on the other hand, is of superior quaUty and... 

Plastics and Other Synthetic Products. Sulfur is used in the production of a wide range of synthetics, including cellulose acetate, cellophane, rayon, viscose products, fibers, and textiles. These uses may account for 2% of sulfur demand in developed countries. Sulfur intermediates for these manufacturing processes are equally divided between carbon disulfide and sulfuric acid. 

Reaction of alkali cellulose with carbon disulphide to produce a cellulose xanthate which forms a lyophilic sol with caustic soda. This may be extruded into a coagulating bath containing sulphate ions which hydrolyses the xanthate back to cellulose. This process is known as the viscose process and is that used in the manufacture of rayon. 

Workers employed at facilities that manufacture or use hydrogen sulfide in the production process are especially prone to exposure. Such industries include the manufacture of rayon textiles, lubricants, pulp and paper, and sulfuric acid and inorganic sulfides. Workers in facilities where hydrogen sulfide is produced as a byproduct, such as farms with manure storage pits, petroleum or natural gas drilling operations, landfills, and waste-water treatment plants, may also be exposed to high levels. 

PULP (Wood) PRODUCTION AND PROCESSING. Pulps can be defined as fibrous products derived from cellulosic fiber-contaiumg materials and used in the production of hardboard, fiberboard, paperboard, paper, and molded-pulp products. With suitable chemical modification, pulps can be used in Hie manufacture of rayon, cellulose acetate, and other familiar products. Pulps can be produced from any material containing cellulosic fiber but in North America and several other regions of the world, wood is the predominant source of pulp. This description is confined to the production and processing of wood pulp,... 

Rayon. Viscose rayon, like cotton, is comprised of cellulose. In the manufacturing process, wood pulp is treated with alkali and carbon disulfide to form cellulose xanthate. Subsequently, the reaction mass is forced through a spinneret and precipitated in an acid coagulation bath as it is formed into a continuous filament. The fiber has a round striated cross-section. Rayon staple is made by breaking the continuous strands into staple-length fibers. Viscose rayon is conventionally produced in diameters varying from 9 to 43 microns. 

Dyes and color pigments Leather tanning and leather processing Rayon and synthetic hber manufacturing Sodium/potassium cyanide-associated industries Basic drugs manufacturing Foundry industries Storage batteries (lead acid type)... 

One extraction process used industrially on a large scale is the purification of sodium hydroxide for use in the manufacture of rayon. The sodium hydroxide produced by electrolysis typically contains 1% sodium chloride and 0.1% sodium chlorate as impurities. If a concentrated aqueous solution of sodium hydroxide is extracted with liquid ammonia, the NaCl and NaClOs are partitioned into the ammonia phase in preference over the aqueous phase. The heavier aqueous phase is added to the top of an extraction vessel filled with ammonia, and equilibrium is reached as droplets of it settle through the ammonia phase to the bottom. This procedure reduces impurity concentrations in the sodium hydroxide solution to about 0.08% NaCl and 0.0002% NaClOj. 

In 1989, the estimated distribution of carbon disulfide utilization was as follows 34% of production went to manufacture viscose rayon, 6% to produce cellophane, 38% to produce carbon tetrachloride, 7% to produce rubber chemicals, and 15% to produce pesticides and to solubilize waxes and oils (HSDB 1995). Future use patterns remain uncertain, although it is expected that less may be used to produce viscose rayon, cellulose, and carbon tetrachloride, products for which the demand has declined and for which alternate production processes may be found (HSDB 1995 Mannsville Chemical Products Corp. 1985 Timmerman 1978). Unless substitutes for carbon disulfide are found, its use levels may depend largely on relative import and export levels of textiles and apparel (Mannsville Chemical Products Corp. 1985). Carbon disulfide use for many other specialty industrial purposes is expected to continue (HSDB 1995 Timmerman 1978). 

The first plant for the manufacture of rayon in the United States was built in 1910 by the newly-formed Viscose Corporation of America. Sales of the new product were slow at first, but by 1925, rayon had become more popular than silk. Today, the Cross-Bevan-Beadle method of making rayon is only one of four processes used by the industry to make the fiber. 

With U.S. rights acquired from French interests, Du Pont started to manufacture viscose rayon yam in 1920 and cellophane in 1923, both at Buffalo, New York. Intensive internal research programs led to marked improvements in the process, permitting a long sequence of price reductions and construction of a number of plants across the country to meet the growing sales. Duco lacquer (1923) came directly out of Du Font s research efforts and revolutionized the finishes business. Not only did it provide a better, more durable automobile finish, but application time was reduced from days to hours. Du Pont introduced photographic films in 1924, industrial alcohol in 1925, and also acquired Viscoloid Co. (plastics) the same year to close out the first quarter of the century. 

Carbon fibers can be made by pyrolysis of a hydrocarbon precursor. Rayon was one of the first precursors used to make carbon fibers. During the processing of Rayon fibers into carbon fibers, only 25% of the fiber mass is retained. This made carbon fibers manufactured from Rayon precursors very expensive. Another precursor that has proved to be economical is the polyacrylontrile... 

The conversion of cellulosic wood pulp into a textile fiber dates to the earliest periods of synthetic fiber manufacture viscose rayon and lyocell processes are well known. However, it is stiU conceivable to improve upon... 

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