Pretreatment/Preparation Processes to Reduce Use of Water, Energy and Harsh Chemicals
Resource ManagementJuly 14, 2010
Large quantities of chemicals and water can be used in finishing of a fabric, but today most conventional dyeing and finishing processes use low inputs for water, energy and chemicals. Huntsman Textile Effects and Genencor are two companies taking the lead in developing these environmentally safe and efficient methods to finish fabrics. Huntsman creates, manufactures and markets differentiated chemicals. Genencor, one of the largest biotechnology companies in the world, develops and manufactures industrial enzymes. Genencor textile enzymes are pretreatment processes to improve textile quality, consistency, and performance. Additional information about these organizations can be found on their websites:
Listed below are some critical pretreatment steps to ensuring successful fabric dyeing and quality retention.
Desizing ingredients such as starch are used as strengthening and protection agents coating warp yarns during industrial weaving. Sizing ingredients must be completely removed prior to bleaching and dyeing or printing. This desizing step is critical to ensuring an even and consistent fabric finish.
Desizing with Genencor's amylase enzymes is much more effective, cost efficient, and eco-friendly for manufacturers than chemical desizing methods. Treatments with acids, hot alkali, or oxidizing agents tend to create waste of as much as fifty percent unusable water due to the high biological oxygen demand (BOD).
Historically, the textile bleaching process requires temperatures of 95°C. In September 2009, Huntsman and Genencor announced the results of their joint development effort: Gentle Power BleachTM. Genencor's new enzyme allows textile bleaching to occur at 65°C with neutral pH levels. The system is offered to the global textile processing industry by Huntsman and based on unique enzyme innovation by Genencor, called PrimaGreen® EcoWhite. Extensive applications research of the technology by Huntsman has resulted in the Gentle Power BleachTM system, which:
• offers a versatile bleaching technology for all fibers that are temperature and pH sensitive
• results in fabrics that have a superior handle compared to conventionally bleached goods, with a permanent soft and natural handle
• provide better dyeing results, thus noticeably brighter shades and potential savings in dyeing cost
• savings in energy consumption due to lower treatment and rinsing temperatures
• reduces fabric weight loss during the pretreatment phase
After fabric or yarn bleaching, residues of hydrogen peroxide are left in the bath, and need to be completely removed prior to the dyeing process, using a step called bleach cleanup. Incomplete peroxide removal results in poor dyeing with distinct change of color shade and intensity, as well as patchy, inconsistent dye distribution.
Genencor's cellulases improve fabric appearance by removing surface fibrils and pills and reducing dead and immature cotton. This prevents subsequent pilling during wash and wear upgrading overall textile quality. Biofinishing creates a smoother fabric surface resulting in fabric that is softer to the touch and drapes better. In addition, PRIMAFAST® LUNA products preserve fabric color by minimizing shade changes during biofinishing and improving fabric strength retention. These benefits allow biofinishing to be completed after the dyeing process.