The production of regenerated cellulosic fibers accounts for about 8 percent of global man-made fibers.1 Regenerated fibers of cellulose origin – (viscose) rayon, lyocell, modal, and cupro – are made of cellulose originating from wood, cotton, and bamboo using differing manufacturing processes with common roots.
To transform hard wood-derived materials into silky fabric through a generic viscose process, the cellulose must be separated from other compounds found in trees or plants and then turned into a cellulose wood pulp. Sodium hydroxide (caustic soda) and sodium sulfide are commonly used to remove the lignin that binds the wood fibers together in order to produce the wood pulp. In some cases there is a requirement to bleach the pulp to achieve a whiter appearance. In a controlled but complex process the pulp is steeped in caustic soda to produce alkali cellulose, which is then aged or oxidized before reacting with carbon disulphide to create the sodium cellulose xanthate. This xanthate form is then dissolved in caustic soda to form the syrup-like spinning solution. Ripening, filtration, spinning, and washing complete the fiber making process.
The pulp manufacturing process requires large amounts of water. Producing generic viscose fibers involves the use of many chemicals that can be released into waterways if not properly reclaimed or neutralized in wastewater effluents. The environmental and health and safety hazard is mainly related to an individual fiber manufacturing facility and its ability to manage production waste and effectively treat waste water before discharging to community rivers and streams or dumping into landfills.
TENCEL® is the registered Lenzing brand name for its lyocell fibers. Lyocell technology was pioneered in the U.S.A. by Eastman Kodak and American Enka during the mid 20thcentury. Courtaulds persisted with the technology and commercialized it in the late 1980’s. It is a fiber made from cellulose originating from eucalyptus wood.
In TENCEL® production, the pulp manufacturing is relatively similar to generic viscose processing. The primary differences occur during pulp transformation for wet spinning. The fiber manufacturing process is a much more elegant and simple process with significantly reduced environmental impact.