The use of enzymes in textile wet processing results in time, energy and water savings; as well as improved product quality
Modern society expects biotechnology to be the answer for many worldwide problems like depletion of energy sources, incurable illnesses and pollution, among other problems. Industrial use of biotechnology, known as white biotechnology, is bringing about new products and processes aimed at the use of renewable resources, as well as the application of green technologies with low energy consumption and environmentally healthy practices.
Textile processing is a growing industry that traditionally has used a lot of water, energy and harsh chemicals – starting from pesticides for cotton-growing to high amounts of wash waters that result in waste streams causing high environmental burdens.
As textile fibers are polymers, the majority being of natural origin, it is reasonable to expect there would be a lot of opportunities for the application of white biotechnology to textile processing.
Enzymes nature’s catalysts – are the logical tools for the development of new biotechnology-based solutions for textile wet processing. Though the focus on white biotechnology is a new phenomenon, the use of enzymes in textile treatment has a long history.
Biotechnology-based processes were applied nearly 2,000 years ago when microbes were used as aids in bast fiber-retting. The first enzyme application, as early as 1912, was the use of barley for removal of starchy size from woven fabrics.
The first microbial amylases were used in the 1950s for the same desizing process, which today is routinely used by the industry.
Since then, several other enzymes have been introduced for industrial applications; and enzymes such as celluloses, catalyzes, lactases and pectinases are increasingly gaining a foothold in the textile industry as improved application processes are developed.
The use of enzyme technology is attractive because enzymes are highly specific and efficient, and work under mild conditions.
Furthermore, the use of enzymes results in reduced process times, energy and water savings; improved product quality; and potential process integration. Following is a review of common enzymes currently used in textile applications.
Cellulose enzymes were first introduced after decades of amylase usage as an industry standard for desizing processes. During the 1970s, the popularity of denim garments increased as new garment wet processes changed denim’s look and feel from the hard, dark blue garments used as work wear into soft and smooth fashion items with an abraded look.
Surprisingly, this look, first achieved by using pumice stones, also can be attained using cellulose enzymes. Celluloses loosen the surface fibers of the denim garment so that mechanical action in a washing machine breaks the surface to remove the indigo dye, revealing the white core of the ring-dyed yarns.
The first cellulose products for this application were introduced in the 1980s, and today, most denim garments are “stonewashed” using celluloses, either alone or in combination with a reduced amount of stones.
The introduction of celluloses resulted in increased washing capacity for the laundries, and reduced damage to garments as well as to washing machines, in addition to diminishing environmental effects from pumice stone mining and disposal of used pumice.
It also was realized that cellulose applications could be extended to surface and hand modification of cellulosic. The small fibers or fibrils protruding from the fabric render a fuzzy surface, and the gradual entanglement of fibrils results in the formation of pills when a garment is worn and washed.
Removal of surface fibrils improves fabric quality, keeping the garment in good form for a longer time.
The use of celluloses, combined with the synergistic action of the processing machines, is effective in removing the fibrils, leading to permanent improvement of fabric quality, including cleaner and smoother surface, softer hand and improved fabric drape.
This treatment, called bio-polishing, is widely used today in garment processing and in batch processing of woven and knitted fabrics. As today’s process needs a dwell time of 20 to 40 minutes in a high-mechanical-action system, the challenge is to create a consistent, continuous bio-polishing process.