Viscose and Modal fiber production
Viscose and Modal production
The production of fibers using the viscose process is a chemical-technological process that proceeds in multiple steps. The individual stages, which are electronically controlled and constantly monitored, determine the processability of the viscose and quality of fibers.
Dissolving wood pulp is steeped in a sodium hydroxide solution and converted to alkali cellulose. The addition of carbon disulfide causes cellulose xanthate to form. The xanthate is dissolved in diluted sodium hydroxide solution, filtered, deaerated, ripened and metered through spinnerets into a sulfate regenerating bath. After that, the fibers are stretched, cut, desulfurized and bleached with a sodium hypochlorite solution or a hydrogen peroxide solution.
Production process Lenzing Viscose® und Lenzing Modal®
*) NaOH (caustic soda), CS2 (carbon disulfide), ZnSO2 (zinc sulfate), H2SO4 (acid sulfur)
Serveral after treatment steps
The fibers are repeatedly washed between the individual subsequent treatment steps. After the last wash, finishing agents are applied to ensure the running and gliding properties for further processing.
As a final step, the fibers are dried and pressed into bales. Zinc sulfate is removed or recovered from the wastewater (at the Lenzing site only).
Sulfur-containing gases generated during spinning are collected and recovered once again in the purest form as the chemicals carbon disulfide and sulfuric acid. The co-product sodium sulfate is produced from the input chemicals sulfuric acid and sodium hydroxide solution.
Production of modal fiber
Modal is a viscose fiber refined through modified viscose production conditions and spinning conditions. The special characteristics of Lenzing Modal® are improved washability due to greater tenacity, especially when wet, which in turn gives textiles greater dimensional stability. It stands apart for its ultra-softness and is the preferred fiber for high-quality linens and similar products.