Wednesday, 30 March 2011 02:22

Viscose (Rayon)

Rate this item
(2 votes)

Adapted from 3rd edition, Encyclopaedia of Occupational Health and Safety.

Rayon is a synthetic fibre produced from cellulose (wood pulp) that has been chemically treated. It is used alone or in blends with other synthetic or natural fibres to make fabrics that are strong, highly absorbent and soft, and which can be dyed in brilliant, long-lasting colours.

The manufacture of rayon had its origins in the quest for an artificial silk. In 1664, Robert Hooke, a British scientist noted for his observations of plant cells, predicted the possibility of duplicating silk by artificial means; almost two centuries later, in 1855, fibres were made from a mixture of mulberry twigs and nitric acid. The first successful commercial process was developed in 1884 by the French inventor Hilaire de Chardonnet, and in 1891, the British scientists Cross and Bevan perfected the viscose process. By 1895, rayon was being produced commercially on a rather small scale, and its use grew rapidly.

Production Methods

Rayon is made by a number of processes, depending on its intended use.

In the viscose process, cellulose derived from wood pulp is steeped in a sodium hydroxide solution, and the excess liquid is squeezed out by compression to form alkali cellulose. Impurities are removed and, after being torn into shreds similar to white crumbs that are allowed to age for several days at a controlled temperature, the shredded alkali cellulose is transferred to another tank where it is treated with carbon disulphide to form golden-orange crumbs of cellulose xanthate. These are dissolved in dilute sodium hydroxide to form a viscous orange liquid called viscose. Different batches of viscose are blended to obtain uniform quality. The mixture is filtered and ripened by several days of storage at rigidly controlled temperature and humidity. It is then extruded through metal nozzles with fine holes (spinnerets) into a bath of about 10% sulphuric acid. It can be wound as a continuous filament (cakes) or cut into the required lengths and spun like cotton or wool. Viscose rayon is used to make wearing apparel and heavy fabrics.

In the cuprammonium process, used to make silk-like fabrics and sheer hosiery, the cellulose pulp dissolved in the sodium hydroxide solution is treated with copper oxide and ammonia. The filaments come out of the spinnerets into a spinning funnel and are then stretched to the required fineness by the action of a jet stream of water.

In the viscose and cuprammonium processes, the cellulose is reconstituted, but acetate and triacetate are esters of the cellulose and are considered by some to be a separate class of fibre. Acetate fabrics are known for their ability to take brilliant colours and to drape well, features that make them particularly desirable for apparel. Short fibres of acetate are used as fillers in pillows, mattress pads and quilts. Triacetate yarns have many of the same properties as acetate but are particularly favoured for their ability to retain creases and pleats in garments.

Hazards and Their Prevention

The principal hazards in the viscose process are the exposures to carbon disulphide and hydrogen sulphide. Both have a variety of toxic effects depending on the intensity and duration of the exposure and the organ(s) affected; they range from fatigue and giddiness, respiratory irritation and gastrointestinal symptoms to profound neuropsychiatric disturbances, auditory and visual disorders, deep unconsciousness and death.

Moreover, with a flashpoint below –30 °C and explosive limits between 1.0 and 50%, carbon disulphide has a high risk of fire and explosion.

The acids and alkalis used in the process are fairly dilute, but there is always danger from the preparing of the proper dilutions and splashes into the eyes. The alkaline crumbs produced during the shredding process may irritate workers’ hands and eyes, while the acid fumes and hydrogen sulphide gas emanating from the spinning bath may cause a kerato-conjunctivitis characterized by excessive lachrimation, photophobia and severe ocular pain.

Keeping the concentrations of carbon disulphide and hydrogen sulphide below the safe exposure limits requires diligent monitoring such as may be provided by an automatic continuous recording apparatus. Complete enclosure of the machinery with efficient LEV (with intakes at floor levels since these gases are heavier than air) is advisable. Workers must be trained in emergency responses in the event of leaks, and, in addition to being provided with proper personal protective equipment, maintenance and repair workers must be carefully schooled and supervised to avoid unnecessary levels of exposure.

Rest rooms and washing up facilities are necessities rather than mere amenities. Medical surveillance through preplacement and periodic medical examinations is desirable.



Read 6380 times Last modified on Wednesday, 29 June 2011 08:17
More in this category: « Silk Industry Synthetic Fibres »

" DISCLAIMER: The ILO does not take responsibility for content presented on this web portal that is presented in any language other than English, which is the language used for the initial production and peer-review of original content. Certain statistics have not been updated since the production of the 4th edition of the Encyclopaedia (1998)."


Textile Goods Industry References

American Textile Reporter. 1969. (10 July).

Anthony, HM and GM Thomas. 1970. Tumors of the urinary bladder. J Natl Cancer Inst 45:879–95.

Arlidge, JT. 1892. The Hygiene, Diseases and Mortality of Occupations. London: Percival and Co.

Beck, GJ, CA Doyle, and EN Schachter. 1981. Smoking and lung function. Am Rev Resp Dis 123:149–155.

—. 1982. A longitudinal study of respiratory health in a rural community. Am Rev Resp Dis 125:375–381.

Beck, GJ, LR Maunder, and EN Schachter. 1984. Cotton dust and smoking effects on lung function in cotton textile workers. Am J Epidemiol 119:33–43.

Beck, GJ, EN Schachter, L Maunder, and A Bouhuys. 1981. The relation of lung function to subsequent employment and mortality in cotton textile workers. Chest suppl 79:26S–29S.

Bouhuys, A. 1974. Breathing. New York: Grune & Stratton.

Bouhuys, A, GJ Beck, and J Schoenberg. 1979. Epidemiology of environmental lung disease. Yale J Biol Med 52:191–210.

Bouhuys, A, CA Mitchell, RSF Schilling, and E Zuskin. 1973. A physiological study of byssinosis in colonial America. Trans New York Acad Sciences 35:537–546.

Bouhuys, A, JB Schoenberg, GJ Beck, and RSF Schilling. 1977. Epidemiology of chronic lung disease in a cotton mill community. Lung 154:167–186.

Britten, RH, JJ Bloomfield, and JC Goddard. 1933. Health of Workers in Textile Plants. Bulletin No. 207. Washington, DC: US Public Health Service.

Buiatti, E, A Barchielli, M Geddes, L Natasi, D Kriebel, M Franchini, and G Scarselli. 1984. Risk factors in male infertility. Arch Environ Health 39:266–270.

Doig, AT. 1949. Other lung diseases due to dust. Postgrad Med J 25:639–649.

Department of Labor (DOL). 1945. Special Bulletin No. 18. Washington, DC: DOL, Labor Standards Division.

Dubrow, R and DM Gute. 1988. Cause-specific mortality among male textile workers in Rhode Island. Am J Ind Med 13: 439–454.

Edwards, C, J Macartney, G Rooke, and F Ward. 1975. The pathology of the lung in byssinotics. Thorax 30:612–623.

Estlander, T. 1988. Allergic dermatoses and respiratory diseases from reactive dyes. Contact Dermat 18:290–297.

Eyeland, GM, GA Burkhart, TM Schnorr, FW Hornung, JM Fajen, and ST Lee. 1992. Effects of exposure to carbon disulphide on low density lipoprotein cholesterol concentration and diastolic blood pressure. Brit J Ind Med 49:287–293.

Fishwick, D, AM Fletcher, AC Pickering, R McNiven, and EB Faragher. 1996. Lung function in Lancashire cotton and man-made fibre spinning mill operatives. Occup Environ Med 53:46–50.

Forst, L and D Hryhorczuk. 1988. Occupational tarsal tunnel syndrome. Brit J Ind Med 45:277–278.

Fox, AJ, JBL Tombleson, A Watt, and AG Wilkie. 1973a. A survey of respiratory disease in cotton operatives: Part I. Symptoms and ventilation test results. Brit J Ind Med 30:42-47.

—. 1973b. A survey of respiratory disease in cotton operatives: Part II. Symptoms, dust estimation, and the effect of smoking habit. Brit J Ind Med 30:48-53.

Glindmeyer, HW, JJ Lefante, RN Jones, RJ Rando, HMA Kader, and H Weill. 1991. Exposure-related declines in the lung function of cotton textile workers. Am Rev Respir Dis 144:675–683.

Glindmeyer, HW, JJ Lefante, RN Jones, RJ Rando, and H Weill. 1994. Cotton dust and across-shift change in FEV1 Am J Respir Crit Care Med 149:584–590.

Goldberg, MS and G Theriault. 1994a. Retrospective cohort study of workers of a synthetic textiles plant in Quebec II. Am J Ind Med 25:909–922.

—. 1994b. Retrospective cohort study of workers of a synthetic textiles plant in Quebec I. Am J Ind Med 25:889–907.

Grund, N. 1995. Environmental considerations for textile printing products. Journal of the Society of Dyers and Colourists 111 (1/2):7–10.

Harris, TR, JA Merchant, KH Kilburn, and JD Hamilton. 1972. Byssinosis and respiratory diseases in cotton mill workers. J Occup Med 14: 199–206.

Henderson, V and PE Enterline. 1973. An unusual mortality experience in cotton textile workers. J Occup Med 15: 717–719.

Hernberg, S, T Partanen, and CH Nordman. 1970. Coronary heart disease among workers exposed to carbon disulphide. Brit J Ind Med 27:313–325.

McKerrow, CB and RSF Schilling. 1961. A pilot enquiry into byssinosis in two cotton mills in the United States. JAMA 177:850–853.

McKerrow, CB, SA Roach, JC Gilson, and RSF Schilling. 1962. The size of cotton dust particles causing byssinosis: An environmental and physiological study. Brit J Ind Med 19:1–8.

Merchant, JA and C Ortmeyer. 1981. Mortality of employees of two cotton mills in North Carolina. Chest suppl 79: 6S–11S.

Merchant, JA, JC Lumsdun, KH Kilburn, WM O’Fallon, JR Ujda, VH Germino, and JD Hamilton. 1973. Dose-response studies in cotton textile workers. J Occup Med 15:222–230.

Ministry of International Trade and Industry (Japan). 1996. Asia-Pacific Textile and Clothing Industry Form, June 3-4, 1996. Tokyo: Ministry of International Trade and Industry.

Molyneux, MKB and JBL Tombleson. 1970. An epidemiological study of respiratory symptoms in Lancashire mills, 1963–1966. Brit J Ind Med 27:225–234.

Moran, TJ. 1983. Emphysema and other chronic lung disease in textile workers: An 18-year autopsy study. Arch Environ Health 38:267–276.

Murray, R, J Dingwall-Fordyce, and RE Lane. 1957. An outbreak of weaver’s cough associated with tamarind seed powder. Brit J Ind Med 14:105–110.

Mustafa, KY, W Bos, and AS Lakha. 1979. Byssinosis in Tanzanian textile workers. Lung 157:39–44.

Myles, SM and AH Roberts. 1985. Hand injuries in the textile industry. J Hand Surg 10:293–296.

Neal, PA, R Schneiter, and BH Caminita. 1942. Report on acute illness among rural mattress makers using low grade, stained cotton. JAMA 119:1074–1082.

Occupational Safety and Health Administration (OSHA). 1985. Final Rule for Occupational Exposure to Cotton Dust. Federal Register 50, 51120-51179 (13 Dec. 1985). 29 CFR 1910.1043. Washington, DC: OSHA.

Parikh, JR. 1992. Byssinosis in developing countries. Brit J Ind Med 49:217–219.
Rachootin, P and J Olsen. 1983. The risk of infertility and delayed conception associated with exposures in the Danish workplace. J Occup Med 25:394–402.

Ramazzini, B. 1964. Diseases of Workers [De morbis artificum, 1713], translated by WC Wright. New York: Hafner Publishing Co.

Redlich, CA, WS Beckett, J Sparer, KW Barwick, CA Riely, H Miller, SL Sigal, SL Shalat, and MR Cullen. 1988. Liver disease associated with occupational exposure to the solvent dimethylformamide. Ann Int Med 108:680–686.

Riihimaki, V, H Kivisto, K Peltonen, E Helpio, and A Aitio. 1992. Assessment of exposures to carbon disulfide in viscose production workers from urinary 2-thiothiazolidine-4-carboxylic acid determinations. Am J Ind Med 22:85–97.

Roach, SA and RSF Schilling. 1960. A clinical and environmental study of byssinosis in the Lancashire cotton industry. Brit J Ind Med 17:1–9.

Rooke, GB. 1981a. The pathology of byssinosis. Chest suppl 79:67S–71S.

—. 1981b. Compensation for byssinosis in Great Britain. Chest suppl 79:124S–127S.

Sadhro, S, P Duhra, and IS Foulds. 1989. Occupational dermatitis from Synocril Red 3b liquid (CI Basic Red 22). Contact Dermat 21:316–320.

Schachter, EN, MC Kapp, GJ Beck, LR Maunder, and TJ Witek. 1989. Smoking and cotton dust effects in cotton textile workers. Chest 95: 997–1003.

Schilling, RSF. 1956. Byssinosis in cotton and other textile workers. Lancet 1:261–267, 319–324.

—. 1981. Worldwide problems of byssinosis. Chest suppl 79:3S–5S.

Schilling, RSF and N Goodman. 1951. Cardiovascular disease in cotton workers. Brit J Ind Med 8:77–87.

Seidenari, S, BM Mauzini, and P Danese. 1991. Contact sensitization to textile dyes: Description of 100 subjects. Contact Dermat 24:253–258.

Siemiatycki, J, R Dewar, L Nadon, and M Gerin. 1994. Occupational risk factors for bladder cancer. Am J Epidemiol 140:1061–1080.

Silverman, DJ, LI Levin, RN Hoover, and P Hartge. 1989. Occupational risks of bladder cancer in the United States. I. White men. J Natl Cancer Inst 81:1472–1480.

Steenland, K, C Burnett, and AM Osorio. 1987. A case control study of bladder cancer using city directories as a source of occupational data. Am J Epidemiol 126:247–257.

Sweetnam, PM, SWS Taylor, and PC Elwood. 1986. Exposure to carbon disulphide and ischemic heart disease in a viscose rayon factory. Brit J Ind Med 44:220–227.

Thomas, RE. 1991. Report on a multidisciplinary conference on control and prevention of cumulative trauma disorders (CDT) or repetitive motion trauma (RMT) in the textile, apparel and fiber industries. Am Ind Hyg Assoc J 52:A562.

Uragoda, CG. 1977. An investigation into the health of kapok workers. Brit J Ind Med 34:181–185.
Vigliani, EC, L Parmeggiani, and C Sassi. 1954. Studio de un epidemio di bronchite asmatica fra gli operi di una tessiture di cotone. Med Lau 45:349–378.

Vobecky, J, G Devroede, and J Caro. 1984. Risk of large-bowel cancer in synthetic fiber manufacture. Cancer 54:2537–2542.

Vobecky, J, G Devroede, J La Caille, and A Waiter. 1979. An occupational group with a high risk of large bowel cancer. Gastroenterology 76:657.

Wood, CH and SA Roach. 1964. Dust in cardrooms: A continuing problem in the cotton spinning industry. Brit J Ind Med 21:180–186.

Zuskin, E, D Ivankovic, EN Schachter, and TJ Witek. 1991. A ten year follow-up study of cotton textile workers. Am Rev Respir Dis 143:301–305.