The Textile Industry
Enzymes are being used increasingly in textile processing, mainly in the finishing of fabrics and garments. The most important applications of enzymes are reviewed here. Desizing is an enzyme application dating back to the beginning of the 20th century, but the others have all been developed in the last 15 years.
In the case of fabrics made from cotton or blends of cotton and synthetic fibres, the warp (longitudinal) threads are coated with an adhesive substance known as a ‘size’. This is to prevent the threads breaking during weaving. The most common sizes are starches and starch derivatives. After weaving, the size must be removed again in order to prepare the fabric for finishing (bleaching, dyeing, printing, water or creaseproofing, etc.).
This process (desizing) may be carried out by treating the fabric with strong chemicals such as acids, bases or oxidizing agents. However, starchsplitting enzymes (amylases) have been preferred for many years due to their high efficiency and specific action. Amylases bring about complete removal of the size without any harmful effects on the fabric. Another advantage of enzymes compared to the strong chemicals mentioned above is that the enzymes are harmless to the environment, so the waste water from the process is more acceptable from an environmental point of view.
Cotton and other natural fibres based on cellulose can be improved by an enzymatic treatment known as BioPolishing. As the name suggests, the treatment gives the fabric a smoother and glossier appearance.
The treatment is used to remove ‘fuzz’ – the tiny strands of fibre that protrude from the surface of yarn. A ball of fuzz is called a ‘pill’ in the textile trade. These pills can present a serious quality problem since they result in an unattractive, knotty fabric appearance. After BioPolishing, the fabric shows a much lower pilling tendency. The other benefits of removing fuzz are a softer and smoother handle, and superior colour brightness.
Many ‘casual’ garments are subjected to a wash treatment to give them a slightly worn look. A prime example is the stonewashing of denim jeans. In the traditional stonewashing process, the blue denim was faded by the abrasive action of pumice stones on the garment surface. Nowadays, denim finishers are using a special cellulase to accelerate the abrasion.
The cellulase works by loosening the indigo dye on the denim in a process known as ‘biostoning’. A small dose of enzyme can replace several kilograms of stones. The use of fewer stones results in less damage to the garments, less wear on machines and less pumice dust in the laundry environment.
Biostoning has opened up new possibilities in denim finishing by increasing the variety of finishes available. For example, it is now possible to fade denim to a greater degree without running the risk of damaging the garment. Productivity can also be increased because laundry machines contain fewer stones and more garments.
Natural fabrics such as cotton are normally bleached with hydrogen peroxide before dyeing. Bleaches are highly reactive chemicals and any peroxide left on the fabric can interfere with the dyeing process. That’s why a thorough ‘Bleach Cleanup’ is necessary. The traditional method is to neutralize the bleach with a reducing agent, but the dose has to be controlled precisely. Enzymes present a more convenient alternative because they are easier and quicker to use. A small dose of catalase is capable of breaking down hydrogen peroxide into water and oxygen. Compared with the traditional cleanup methods, the enzymatic process results in cleaner waste water or reduced water consumption.
Please note that all products listed are not necessarily available in all countries. Contact your local sales office for details.
For silk degumming.
For low to medium/high-temperature desizing processes.
For fabric preparation.
For denim bleaching.
For denim finishing.
Dispersant agent for denim finishing.
For wool finishing.
For high-temperature and continuous desizing processes.
For bleach cleanup.