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| Issue date:01/08/2007 |
| ATA Journal for Asia on Textile & Apparel - Aug 2007 Issue |
| Source:Journal for Asia on Textile & Apparel |
| by Staff Reporters |
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| Environmental friendly textile preparation treatments with enzymes have become one of the key development directions toward clean textile production. |
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| Enzymes used in the textile industry (Photo from Novozymes) |
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According to the Association of Manufacturers and Formulators of Enzyme Products (AMFEP) in Europe, enzymes are proteins composed of amino acids. As biological catalysts, they can replace chemical catalysts in many processes. Enzymes are often more effective, need less energy and they function under milder conditions than chemicals.
At present, enzymes, such as a-amylases, cellulases, catalases, proteases, laccase and pectate lyase, are widely used in various textile applications.
Cellulases are now commonly used to enhance the appearance and feel of such fabrics as cotton, linen, lyocell, viscose and polynosic rayon. Catalase is used to eliminate residual hydrogen peroxide, following bleaching or water recycling in a dye house, while proteases are used for softening and preventing wool from pilling, as well as for sandwashing of silk. On the other hand, laccase is used for controlled bleaching of indigo dyed fabrics, and pectate lyase is capable of removing impurities from cotton.
Bio-scouring
With more than 100 types of enzymes and microorganisms and around 700 different products, Novozymes is one of the biggest players in the industry of enzymes with three major business areas of technical, food and feed enzymes. Its technical enzymes are applied in the textile industry to enhance clean production.
Traditionally, highly alkaline chemicals such as sodium hydroxide are used for scouring. These chemicals, however, not only remove the impurities but also weaken the cotton fabric in terms of strength and weight. Moreover, the resulting wastewater has a high chemical oxygen demand (COD), biochemical oxygen demand (BOD) and salt content.
Novozymes believes that Scourzyme L represents a biological alternative. Instead of extremes of pH and temperature, bio-scouring with Scourzyme L runs at moderate temperatures and pH. The enzyme process also works out cheaper as it saves energy, consumes less water and needs minimum effluent treatment. Water consumption is usually 20-30% lower.
A recent user Vijayeswari Textiles in Coimbatore, India has switched to the biological scouring (bio-scouring) process with Novozymes Scourzyme L that removes impurities in native cotton. It also adopts the use of the amylase Aquazym for desizing (starch removal), and the cellulase Cellusoft L for bio-polishing in the finishing stage. In this way, the company has been able to reduce the use of auxiliaries. The only auxiliary used in the bio-scouring system at Vijayeswari Textiles is a wetting agent.
Bio-polishing
Fabrics containing natural cotton fibers often have tiny loose yarns on the surface, which usually become tangled with repeated wearing and washing, making the new garments look worn. By removing the loose fibers, the treatment of bio-polishing helps improve the texture and appearance of fabrics.
Novozymes' recent product, Cellusoft CR, operates across a wider pH range than the conventional cellulases used in bio-polishing, so that the users need not adjust the pH of the solution after dyeing or bleaching, reducing the total time needed for the bio-polishing process.
In the area of denim treatments, Novozymes has products applicable for denim bleaching, denim abrasion, biopolishing and desizing.
Denim processing and pretreatment solutions
A Danisco Division, Genencor is another major developer and manufacturer of industrial enzymes and one of the top ten biotechnology companies in the world.
The company offers a variety of products for denim wet processing from start to finish - pretreatment through stonewashing and clean up. It believes that these enzyme innovations provide a number of advantages to fabric processors and designers, including the ease of use, efficiency and reduced processing time, improved denim quality with better strength retention, and reduced use of chemicals and natural resources, with lower waste emissions. For instance, with the Genencor's Protex OXG, users are able to perform backstaining cleanup, but avoid unwanted discoloration on the white parts of the garment.
The company also provides pretreatment solutions in desizing with its amylase enzymes, and bleach cleanup prior to dyeing with its catalase products.
Indian players in the industry
In Asia, some biotechnological companies are committed to offering eco-friendly alternatives for textile processing.
Maps, an Indian biotechnology company producing enzymes and microorganisms, offers a product portfolio of some 60 products for more than 10 different industries, making it among the top 50 biotech companies in India. Employing over 150 staff, the company is a major producer and exporter of enzymes and microorganisms in the country.
The company's research and development team has developed an array of products for fabric treatment. It currently provides a range of enzymes like amylases, cellulases, catalase, pectinase and protease for various textile wet-processing applications like desizing, bio-polishing, denim finishing, bleach clean-up, bio-scouring and de-wooling.
Also based in India, Advanced Enzyme Technologies Ltd (AETL) produces a full spectrum of industrial enzymes derived from all four natural origins: plant, vegetable, fungus, and bacteria. And it uses both solid state and submerged culture techniques of fermentation.
In 2004, AETL introduced Addscour to perform bio-preparation that requires much less rinsing water compared with traditional processes. It reduces the total water consumption by around one-fourth, while the treated yarn/fabrics retain their strength properties.
Enzymes like heat stable amylase and fungal amylase are used for desizing woven fabrics. Meanwhile, the Neutral cellulases or Neutrastone series designed by AETL acting at pH 6-8, acid cellulases (Denicell Series) acting at pH 4-6 and hybrid cellulases (Addcool Series) acting at pH 5 - 6.5 are used for the abrasion of denim. They are used to conduct backstaining and other denim finishing.
In addition, AETL provides other enzyme products including laccase and peroxidase to replace bleaching chemicals like hydrogen peroxide or hypochlorite, as well as items to perform bio-finishing and various textile-related processes in a more environmentally responsible manner.
New dyeing and finishing technologies improve profits
by Tiffany Zhu
At the recent "2007 China international dyeing & finishing technology and first-time-correct dyeing forum" held in Hangzhou, more than 270 experts and industrial players shared their know-how in the field.
The forum was organized by the China Textile Engineering Society (CTES) and China Textile Information Center (CTIC), and co-organized by CTES Consultative Department, CTES Dyeing & Finishing Committee, China Printing & Dyeing Technical Information Center and Adsale Publishing Limited.
The recently approved regulation, REACH that restricts the use of various chemicals in products was intensely discussed. Dr Jane Jiang, Technical Director of Softline — Asia Pacific, SGS-CSTC Standards Technical Services Co Ltd outlined the key international technical requirements in REACH and future directions of the environmental protection development in the world. Meanwhile, Oeko-Tex presented the Eco-Label and essential ecological concepts for the textile industry.
Professor Wang Jianping of Intertek Group advised manufacturers to put more efforts in the areas of risk management and indication of chemicals used.
Dr Gao Ming of Bureau Veritas Shanghai Laboratory explained the three major areas of the REACH that affected the dyeing and finishing industry, namely pretreatment, dyeing and finishing. He suggested that the related producers should diversify the use of dyestuffs and auxiliaries so as to keep any single chemical substance used on printed/dyed products under one ton per year. Secondly, they should avoid using dyestuffs and auxiliaries that contain substances of very high concern (SVHC). They can also adopt more extensively the environment-friendly alternatives to reduce the chemical use.
Over 270 industrial insiders attended the forum |
Downstream fashion company Hennes & Mauritz explained that to suppliers, the best way to comply with H&M regulations on chemical restrictions was to monitor the chemicals used in production instead of testing on the end products chemical Engineer Elin Robling said: "If you make sure the chemicals used in dyeing, finishing and washing processes do not contain alkylphenol ethoxylates (APEO), you can be sure that no end products will contain APEO." APEO is the name of a group of surfactants that are harmful to the environment.
Dyeing right
At the same occasion, Chinese experts shared their views on how to improve the first-time-correct rate of dyeing. Professor Zhang Jie of China Dyestuff Society outlined the related new textile chemicals and new technologies at the conference. In particular, he underscored new technologies such as Dyexact XP system and ECON dye Plus technology for synthetic fibers. For cotton fabrics, technologies from InnoVat, Econtrol and Luft-rotoplus can be considered. |
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| Copyright © Adsale Publishing Limited. Any party needs to reprint any part of the content should get the written approval from Adsale Publishing Ltd and quote the source "ATA Journal for Asia on Textile & Apparel", Adsale Textile English Website - www.AdsaleATA.com. We reserve the right to take legal action against any party who reprints any part of this article without acknowledgement. For enquiry, please contact Editorial Department. |
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| Copyright © Adsale Publishing Limited. Any party needs to reprint any part of the content should get the written approval from Adsale Publishing Ltd and quote the source "ATA Journal for Asia on Textile & Apparel", Adsale Textile English Website - www.AdsaleATA.com. We reserve the right to take legal action against any party who reprints any part of this article without acknowledgement. For enquiry, please contact Editorial Department. |
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