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Application Of Cellulase In Fabric Finishing

2020/2/25 12:04:00 4

CellulaseFabric

The application of cellulase in cellulose fiber fabric finishing, including cotton fabric scouring, cellulose fabric softening finishing, polishing finishing, denim fabric finishing and Lyocell fiber defibrillation, points out the problems of cellulase application in textile processing.

Author: Yu Yuanyuan, Wang Qiangfan, Xue Rong, School of textile and clothing, Jiangnan University

Introduction of Cellulase

Enzymes are widely used in textile dyeing and finishing because of their high efficiency, specificity, mild conditions and environmental friendly processing. Cellulase is the most widely applied and most successful enzyme preparation.

Cellulase is a group of enzymes that catalyze the hydrolysis of cellulose to produce glucose. At present, commercialized cellulase is mainly produced by fermentation of 2 strains of Trichoderma (Trichodermaspp) and Aspergillus niger (Aspergillusniger).

According to their properties and functions, each component of cellulase can be divided into 3 main categories:

(1) endo-l, 4-D-vlucanase, EC3.2.1.4, EG from fungi, and Cen from bacteria. The enzyme can randomly hydrolyze the P-L and 4- glycosidic bonds in the macromolecular chain of cellulose and form a new reduced terminal.

(2) exo glucan (exo-l, 4-p-D-jucanase, EC3.2.1.91, CBH referred to as fungi, referred to as Cex from bacteria). The enzyme hydrolyzed along the end of cellulose chain and released two sugars in turn.

(3) p- glucosidase (3-D- to lucosidase, EC3.2.1.2l, referred to as BG), also known as fiber two glucosidase. The enzyme will mainly hydrolyze cellulose two sugar, oligosaccharide and oligosaccharide hydrolyzed by endosglucan and exosglucan, and then produce glucose.

In 1980s, American scientists first applied cellulase to cotton fabric finishing. Subsequently, researchers in various countries did a lot of research on the application of cellulase in textile processing. At present, cellulase has been successfully applied to the pretreatment, softening, finishing and denim finishing of cellulosic fabrics.

Application of cellulase in cellulose fiber fabric finishing

Application of 1. cellulase in cotton fabric scouring process

After cotton desizing, most of the natural impurities (such as cottonseed hull, pectin, waxy substance, protein, etc.), slurry and oil residue remain, resulting in poor wettability and yellowing of the fabric, affecting the appearance, handle and subsequent processing of the fabric. Therefore, cotton fabrics need to be scoured to remove natural impurities after desizing. The traditional alkali scouring process of cotton fabric has many shortcomings, such as high energy consumption, large amount of wastewater discharge and serious fiber damage. It has not met the requirements of modern green textile processing.

The use of cellulase for scouring is an important research direction for scientists from all over the world. Cellulase can hydrolyze cellulose, make the tiny fibers attached to impurities weaken and weaken. Under the mechanical action, it can peel off the fabric and achieve the purpose of impurity removal, and cellulase can also degradate cottonseed hull on cotton fiber.

Hu Yingqing studied the degradation of cottonseed hull by cellulase. It was found that the degradation rate of cotton seed shavings treated with cellulase was as high as 80%, which provided a theoretical support for the removal of residual cottonseed husk from cotton fabric by cellulase. Csiszfir and other researchers began to study the application of cellulase in cotton fabric scouring since 1998. It was found that cellulase pretreatment could improve the alkali scouring effect and the weight loss rate of cottonseed hull reached about 80% after combined treatment. The team also studied the degradation of cottonseed husk with commercialized cellulase. It was found that commercialized cellulase could directly degrade cottonseed on the surface of cotton fabric. It was also found that chelating agent EDTA could increase the ability of cellulase to degrade cottonseed hull.

Although cellulase treated cotton fabric can achieve the purpose of removing impurities to a certain extent, the effect is not very satisfactory. In order to further improve the effect of enzyme scouring, more and more studies have been applied to cotton fabric scouring with cellulase and other enzyme preparations (pectinase, protease, lipase, xylanase, keratinase, etc.). In complex enzyme preparations, the synergistic action of various enzyme components allows impurities to be hydrolyzed more rapidly.

At present, the enzymatic scouring of cotton fabrics has not yet been widely applied. The main reason is that enzyme scouring can not achieve the effect of traditional alkali scouring, especially in cottonseed hull removal, so it can not replace alkali scouring.

There are many reasons for the poor effect of enzymatic scouring. First, the impurities in cotton fabrics are very complex, which results in the degradation of single enzyme components and the synergistic effect of multiple enzymes. Secondly, when the optimal conditions of various enzyme reactions are inconsistent, it is difficult to ensure that each enzyme can play a good catalytic hydrolysis role. Enzyme products have not yet appeared commercialized products. If enzyme, keratinases and so on, the enzyme activity of laboratory engineering enzymes is not high, which limits the study of enzymatic scouring. In short, enzyme scouring needs further research and exploration by scientists.

2. application of cellulase in softening finishing of cellulosic fabric

Biological softening is the use of cellulase to hydrolyze cellulose fibers, resulting in the decrease of fiber stiffness and the softness of fabrics.

Yanv and other studies have shown that using cellulase to treat cotton fabric after durable press finishing can improve the feel of the fabric, but it will cause fabric strength and wear resistance to decrease. In his doctoral dissertation, Wu Zanmin studied the application of bio chemical combination to achieve super soft finishing of cotton fabrics. In this study, cotton fabric was treated by cellulase reduction and chemical softening agent. The cotton fabric treated with cellulase can absorb more chemical softeners, and more softeners can enter the fibers from the pores generated by cellulase hydrolysis, thus enhancing the durability of the softening effect. CSlszaF et al. Used cellulase combined with physical and mechanical functions and silicone softeners to finish flax and linen fabrics. It was found that enzyme finishing could significantly weaken the rigidity of flax fibers and effectively improve the handle of linen fabrics. Wang Jihui et al. Studied the wearability of high counts pure ramie fabric treated with cellulase T225. The results showed that after the treatment with cellulase T225, the crease resistance of fabric increased slightly, the handle was softer and the itchy feeling improved.

3. application of cellulase in polishing finishing of cellulose fiber fabrics

The surface of cellulose fiber has many protruding micro fibrils, which makes the fabric easy to pilling under the action of external force and external friction, which affects the finish and feel of the fabric surface. Biological polishing is a kind of finishing using cellulase to improve the surface finish and softness of cellulose fiber fabric. It can hydrolyze the surface and the micro fibrils of cellulosic fabric to make it fragile, so that it can fall off the fabric surface from the friction between fabric and fabric or fabric and equipment. The finishing can be applied to woven and knitted cellulose fabric (cotton and hemp), and can be carried out in any stage of wet processing of textiles, in most cases after bleaching.

Pete and other Trichodermareesei cellulases were used to treat cotton fibers and yarns. After treatment, the fibers became smooth and the yarn hairiness decreased. Sreenath and other cellulase, pectinase and xylanase alone or synergistic treatment of jute / cotton blended fabric, found that cellulase alone can remove the jute and cotton fibers on the fabric, while pectinase and xylanase alone can not be removed. When cellulase, pectinase and xylanase were combined, cellulase could achieve a good polishing effect at low dosage, indicating that the addition of pectinase and xylanase promoted the finishing of cellulase. Fu and other studies showed that ethylenediamine could increase cellulase activity and thermal stability, and the optimum temperature of enzyme increased from 50 to 65 C. Adding ethylenediamine to the finishing process of cellulase can improve the finishing effect and reduce the amount of cellulase.

4. application of cellulase in finishing of denim fabric

Denim fabric is usually made of pure cotton yarn dyed with indigo blue, and coarse denim made of weft yarn without dyed yarn. Because of the poor color fastness to moisture rubbing of indigo dyes, denim fabric can be obtained through special washing methods and is fashionable and popular among consumers. In the early days, cowboy fabrics were washed by stone mill to obtain the "wear through" effect. However, there are some unavoidable defects in water washing and finishing of stone mill. For example, pumice will cause clothing off-line, fabric strength loss and equipment damage when mechanical pumping occurs. Small pumice particles will cause blockage of drainage system of equipment. In addition, washing process will produce lime dust, pollute fabric and affect fabric color.

Cellulase has been successfully applied to the finishing of denim fabrics. Through cellulase hydrolysis of cotton fibers on the surface of denim fabric, under the action of mechanical external force, indigo dye on the fabric surface is removed from the fabric along with the fibers, resulting in the effect of washing with similar stones. Washing with cellulase can basically avoid the problems existing in the water washing of stone mill, and can obtain some other advantages. For example, denim fabrics washed with cellulase can get a more uniform and three-dimensional decorative pattern, bright colors, and can also improve the handle of fabrics in essence. However, because cellulase is easily bound to the indigo dye and then readsorbed on the fabric surface, the phenomenon of re staining will occur in the reprocessing of cellulase denim fabric, which will reduce the washing effect of cellulase.

Acidic cellulase and neutral cellulase can be applied to the finishing of denim fabrics. Acidic cellulase has stronger hydrolysis effect on cellulose fiber, higher washing efficiency, but fabric strength loss is great, finishing reappearance is bad, easy to stain. The activity of neutral cellulase is low, and the same finishing effect is needed for longer finishing time or more enzymes than acidic cellulase. However, neutral cellulase treatment has little effect on fabric strength loss, good reproducibility of finishing effect, and seldom occurs. Acidic cellulase and neutral cellulase have their own advantages and disadvantages. Because the price of acidic cellulase is much lower than that of neutral cellulase, acidic cellulase is used in the actual production of cowboy fabric, and only neutral cellulase is used when finishing some high-grade denim fabrics.

Mamma and other studies have found that protease modification of cellulase can effectively reduce the phenomenon of color change in cellulase treatment of denim fabric. Chen Xinqi et al. Used ultrasonic neutral conditions to reclaim cowboy fabric with neutral cellulase. It was found that ultrasonic wave could improve the activity of neutral cellulase, enhance the fading effect of denim fabric, and improve the fading rate.

5. application of cellulase in defibrillation of Lyocell fibers

Lyocell fiber, also known as Tencel fiber, is used to dissolve cellulose from a tertiary amine oxide NMMO as a solvent to form the spinning solution, and then spin it. Because solvent can be recycled without pollution to the environment, it is called the green fiber of the new century. In addition, Lyocell fiber also has the advantages of soft handle, good hygroscopicity and good strength.

Fibrillation refers to the process that fibers and fibers are wet rubbed with other objects, and some giant fibrils on the fiber surface are stripped from the fiber body and then split into tiny microfiber fibers. Cellulose fibers are generally fibrinolytic, and the degree of fibrillation is the most serious in the use of Lyocell fibers. After the fibrillation of the fabric, the fabric is prone to pilling and dyeing luster, which seriously affects the quality and wearability of the fabric.

Using cellulose to hydrolyze the micro fibrils on the surface of Lyocell fibers, and gradually weaken them, under the synergistic effect of machinery, it can remove the fibers and achieve the purpose of fibrillation. Morgado and other studies found that cellulase treated Lyocell fabrics for a short time could not remove microfiber and fuzz on the fiber surface, but on the contrary, it increased the fibrillation tendency. But when the cellulase treatment time is prolonged, the microfiber and villi on the fiber surface will be removed. In addition, studies have confirmed that mechanical action plays a very important role in the finishing process. Kumar and other days used cellulase to treat Lyocell fabrics. The handle, drape and surface gloss of the treated fabrics were improved. Younsook and other studies showed that dilute alkali pretreatment could further enhance the defibrillation effect of cellulose treated Lyocell fibers.

6. problems in cellulase application in textile processing

Although cellulase has many advantages in textile processing, there are still some problems which restrict its further large-scale application.

1. fabric strength loss after treatment.

Cellulase contains three different enzyme components, endonuclease, exo glucanase, and fiber two glucase. Under the synergistic action of three enzyme components, the amorphous and crystalline regions of cellulose fibers can be hydrolyzed. When three kinds of enzyme components exist at the same time, the three people are used to gather together in the same position on the fiber. Therefore, after the cellulose hydrolyzed by cellulase, there will be "pothole" and partial cracking in the local area of the fiber. In addition, cellulase molecules can diffuse into the fibers and cause damage to the fibers. Because cellulase hydrolysis will cause the unrestricted damage to the cellulose fibers, which cause the fabric to lose too much strength after enzyme treatment.

2. the cost of enzyme preparation is high.

Compared with the cost of traditional chemical treatment, the price of enzyme preparation is relatively high. The profit of textile industry is not high. The high price of enzyme has affected its wide application.

3. the stability of the enzyme is poor and the reproducibility of the process is poor.

Because cellulase activity is difficult to maintain stability, storage conditions and storage time will affect it. In addition, cellulase activity is sensitive to treatment temperature and pH, and a slight fluctuation will affect it. In textile processing, although the conditions of processing and processing of batches are the same, the quality of fabrics after processing is very difficult to be consistent.

Conclusion: Although cellulase still has some problems in textile processing and application, with the continuous development of commercialized cellulase and the progress of technology and technology, its application in cellulose fiber fabric finishing will expand, and it will have great development potential and wide application prospects in textile processing.

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