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How to use enzymes in the pretreatment process?

Views: 1000     Author: Site Editor     Publish Time: 2021-06-09      Origin: Site

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Biological enzyme is a non-toxic, harmless and environmentally friendly (protein) biological activator. The biological enzyme is used in the textile printing and dyeing process with mild processing conditions, low dosage, and cost saving; the enzyme released after the reaction can continue Catalyzes another reaction, which is easily biodegradable, and the pollutants produced are extremely easy to handle; the specificity of the application of enzymes is passed between different types of enzymes (including pectinase, cellulase, and lipase). It produces a certain synergistic effect to remove various impurities on the cotton fiber, thereby improving the refining effect of cotton knitted fabrics (such as hydrophilicity/hair effect, whiteness and dyeing performance, etc.).

 

The biological enzyme preparations used for the pretreatment of cotton knitted fabrics are mainly mixed enzyme preparations with pectinase, cellulase, lipase, laccase, etc. and high-efficiency surfactants as the main components. Its high-efficiency catalytic effect completes the refining at low temperature. , Avoid high temperature and strong alkali processing; on the other hand, enzymes are only catalysts that can catalyze the decomposition of specific substances, specific chemical bonds and specific chemical changes. The mixed enzyme preparations synergistically act on the cottonseed hulls and symbiosis on the fabric.

 

In addition, multi-enzymes and surfactants are synergistic, the first wetting and permeation effect occurs, which promotes the enzyme preparation and the fiber hair of the cotton fiber primary cell wall to degrade alternately and the pectin decomposition to promote each other's synergy; cotton wax due to the primary cell wall of the cotton Pectin and cellulose are degraded and are exposed. With the help of surfactants to emulsify and solubilize, the cottonseed hulls are expanded to obtain corresponding hydrophilicity and level dyeing properties.

 

Pre-treatment with biological enzymes can avoid strong alkali and high temperature and reduce damage to the fabric; this process is more suitable for fabrics that are not resistant to strong alkali and high temperature (such as viscose elastic, modier/tencel cotton, etc.), such as cotton knitted fabrics or Cotton-spandex knitted fabrics are dyed in dark (dark) colors without the need for subsequent oxygen bleaching process, and the effect of energy saving and emission reduction is more significant.

 

Production case: 32S/1C+20D spandex cotton jersey, dyed in deep and dense colors.

 

The traditional alkali cooking process is: cotton knitted fabric→alkali cooking (100℃×40~50min, degreaser lg/L, refined penetrant 0.5~1.0/L, caustic soda 1.5~2.5/L)→hot washing (80℃× 10min)→Acid washing (HAc 0.5g/L, room temperature 10min)→neutral cellulase 0.5~1.0%→reactive dye dyeing→soaping and fixing.

 

The pre-treatment process of the composite enzyme preparation is: knitted fabric → biological enzyme refining [composite enzyme preparation Plus 1~2% (owf), non-ionic penetrant 0.3~0.5g/l, 55~60℃, 20~30min] × no row Liquid heating (80℃, 10min)→neutral cellulase 0.5~1.0%→reactive dye dyeing→soaping and fixing.

 

The purpose of bio-cellulase treatment is to clean the surface of the fabric and reduce the surface fluff; prevent the pilling of the fabric; improve the hand feel and drape of the fabric; improve the water absorption, dye affinity and gloss brightness of the fabric.

 

Because the strong alkali scouring and bleaching process requires multiple washings and picklings, and high-temperature cooking, while the biological enzyme process time is about 30-60 minutes, which shortens the process and the overall cost is lower than that of the high-temperature alkali cooking process; when processing the same product, because The mechanism of the catalytic decomposition of impurities by biological enzymes is different from the alkaline smelting process. The concentration of waste water and pollutants such as CODcr, total nitrogen, total phosphorus and so on are lower than that of the alkaline smelting process, and the energy saving and emission reduction effects are obvious. Biological enzyme technology has unique advantages in terms of its mild effect on fabrics, especially in saving energy, reducing environmental pollution, and improving product quality. It is a clean and green pre-treatment process and is increasingly recognized by printing and dyeing enterprises.

 

However, pectinase cannot remove the pigment and cotton seed hulls in cotton fibers, and it has limitations on improving the whiteness of fabrics/fibers. It is only suitable for dyeing medium and dark colors of cotton fibers with better yarn quality. The main reasons are: First, it is similar to the alkaline cooking method. Compared with enzyme scouring, the effect of removing cotton seed hulls from fabrics is poor; second, the wettability is not enough. After treatment with a single enzyme preparation, the wettability of the fabric is lower than that of conventional high temperature and strong alkali refining; third, the whiteness of the fabric is better. The problem is that biological enzyme bleaching mainly uses laccase/glucose oxidase to produce peroxide for bleaching. The whiteness of the fabric after bleaching is worse than that of the conventional process, and there will be a certain degree of yellowing.


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