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| Viscose process | |
|---|---|
| Name | Viscose process |
| Type | Regenerated cellulose production |
| Inventors | Charles Frederick Cross; Edward John Bevan; Clayton Beadle; Ludwik Pałczyński |
| Introduced | 1890s |
| Products | Rayon; Cellulose film; Cellophane |
| Feedstocks | Wood pulp; Cotton linters |
| Reagents | Sodium hydroxide; Carbon disulfide; Sulfuric acid |
| Industries | Textile industry; Packaging industry; Film manufacturing |
Viscose process is an industrial method for producing regenerated cellulose fibers and films from cellulosic raw materials. Developed in the late 19th century, it underpins manufacture of rayon, cellophane, and related products that transformed textile, packaging, and photographic industries. The process links forestry and pulp sectors with chemical firms and textile manufacturers across Europe, North America, and Asia.
Inventive work leading to the viscose process involved chemists and industrialists active in the late Victorian and Edwardian eras. Key figures include Charles Frederick Cross and Edward John Bevan, whose early patents and collaborations with firms such as Courtaulds and Vickers catalyzed commercialization. Parallel developments by inventors like J. R. Cross and contributions from researchers in Germany and France led to competing plants operated by conglomerates including Cellophane Company and later global expansions by Courtaulds and Courtaulds Textiles. The process influenced labor and capital flows in regions tied to pulp and timber, notably in Scandinavia, Canada, and United States industrial centers. Regulatory and trade environments shaped diffusion through treaties and market shifts such as those following World War I and World War II.
At its core the viscose process transforms cellulose into a soluble xanthate intermediate by reaction with alkali and a sulfur-containing reagent. Native cellulose from sources like Wood pulp or Cotton linters is first treated with caustic soda (sodium hydroxide), then reacted with carbon disulfide to form cellulose xanthate. The cellulose xanthate dissolves in dilute alkali to yield viscous "viscose" solution, which is extruded or cast and then regenerated by acid coagulation using sulfuric acid. This sequence involves well-known reagents and steps studied by chemists associated with institutions such as Royal Society of Chemistry-affiliated laboratories and university departments at places like University of Manchester and University of Cambridge. The mechanism features nucleophilic attack, substitution, and protonation steps; side reactions produce byproducts including hydrogen sulfide and sulfates controlled by industrial chemists and engineers trained in chemical firms like ICI.
Industrial implementations follow a sequence of pulping, alkalization, xanthation, dissolution, aging, filtration, degassing, spinning or casting, and regeneration. Large pulp mills supplying viscose plants include operations in regions like British Columbia and Scandinavia where companies such as Stora Enso and UPM operate. Spinning lines and film casting units engineered by manufacturers such as Rieter and Trützschler shape fibers into staple or filament rayon, while coagulation baths managed by process engineers affiliated with DuPont-era textile research groups regenerate cellulose. Subsequent washing, bleaching, and finishing steps often involve partnerships with textile finishers in industrial clusters like West Yorkshire and Prato. Quality control, process safety, and effluent management engage standards bodies and regulators in jurisdictions including European Union agencies and agencies modeled after Occupational Safety and Health Administration.
Viscose-derived rayon and films possess properties exploited across sectors. Textile-grade rayon exhibits drape and moisture absorbency valued by fashion houses and designers showcased at venues like Paris Fashion Week and by manufacturers supplying firms such as Hanesbrands. Filmy derivatives like cellophane found uses in packaging and photography adopted by companies including Kodak and confectionery firms in markets spanning Tokyo to São Paulo. Medical and technical applications—sutures, surgical dressings, and nonwoven substrates—were developed with research hubs like Johns Hopkins University and industrial partners such as 3M. Performance characteristics (tenacity, elongation, dye affinity) are tuned by crosslinking, mercerization, or blending with fibers supplied by firms like Invista and Lenzing.
Environmental and occupational issues center on emissions and exposure to hazardous chemicals such as carbon disulfide and sulfurous effluents. Historical industrial cases spurred scrutiny by public health authorities and litigation in courts influenced by precedents from jurisdictions including United Kingdom and United States. Environmental regulation evolved with directives and standards promulgated by bodies like European Environment Agency and national ministries modeled after Environment Agency (England and Wales), driving investments in closed-loop recovery systems and effluent treatment technologies developed by engineering firms such as Veolia and SUEZ. Occupational medicine research at institutes like National Institute for Occupational Safety and Health documented neurotoxic and reproductive hazards associated with chronic carbon disulfide exposure, prompting industrial hygiene reforms and process modifications championed by companies complying with standards from organizations like British Standards Institution.
Late 20th and early 21st century innovation produced alternative regenerated cellulose routes and bio-based fibers. Processes such as the lyocell method commercialized by firms like Lenzing and Aditya Birla Group use N-methylmorpholine N-oxide in closed-loop systems to reduce hazardous byproducts. Other developments include solvent-spun cellulose and enzymatic pretreatments researched at universities including ETH Zurich and Massachusetts Institute of Technology and pilot projects by startups in clusters around Silicon Valley and Aachen. Regulatory pressure, sustainability credentials sought by brands participating in initiatives like Textile Exchange and retailers operating in supply chains managed through platforms such as SEDEX have accelerated adoption of cleaner technologies and certification schemes.
Category:Chemical processes