Views: 1000 Author: Site Editor Publish Time: 2022-08-17 Origin: Site
1 It is suitable for desizing amylase mainly based on starch slurry, etc.
Amylase is a general term for enzymes that hydrolyze starch and glycogen, usually catalyzed by amylase to hydrolyze starch slurry on fabrics. Amylase has high desizing efficiency, fast desizing, less pollution, and the fabric is softer than the acid method and the alkali method, and does not damage the fiber. There are many types of amylase. According to different fabrics, different equipment combinations and different technological processes, the currently used desizing methods include dipping method, stacking method, jigging method, continuous washing, etc. Due to the small mechanical effect of amylase desizing and less water consumption, the desizing effect can be achieved under low temperature conditions, and it has distinct environmental protection characteristics.
The application of biological enzyme technology to the dyeing and finishing industry started from fabric desizing, and it is still an important method to remove starch sizing from fabrics. The amylases used for desizing in dyeing and finishing mainly include α-amylase and β-amylase. At present, the amylases used for desizing are mainly developed in the direction of high temperature and high efficiency.
High-temperature amylase can not only improve the desizing efficiency, but also remove chemical slurries such as PVA in the mixed slurry, simplify the process flow, and reduce sewage discharge. Pretreatment with biological enzymes instead of caustic soda can greatly reduce the COD value in the discharged wastewater. The experimental results show that it can be reduced from 19000mg/L to 800mg/L.
Alpha-amylase is used in the desizing process before textile dyeing and finishing, and is used to treat the starch-based pulp. my country's α-amylase strains are very good. There are already α-amylase products with wide pH and temperature ranges and α-amylase products with high temperature resistance, which are suitable for continuous desizing process to improve desizing efficiency and shorten the process. time.
2 Pectinases suitable for removing pectin from cotton fibers
Pectinase is mainly composed of pectin lyase, polygalacturonase, pectate lyase and pectin esterase. The pectic substance is a highly esterified polygalacturonic acid. When pectinase acts on pectin substances, pectin lyase, polygalacturonase, and pectate lyase act directly on the glycoside bond inside the pectin polymer molecular chain, while pectin esterase Hydrolyzes polygalacturonate, creating more sites for polygalacturonase and pectate lyase.
The main purpose of cotton fabric scouring is to remove non-cellulosic substances such as pectin in cotton fabrics, so as to improve the wettability of fibers and fabrics, create conditions for subsequent dyeing, printing, and finishing processing, and ensure subsequent dyeing and printing processing; Improve whiteness and improve bleaching performance. Traditional scouring uses strong chemical reagents - caustic soda and other auxiliary agents at high temperature to remove pectin, wax and other impurities; consumes a lot of energy and water; the pH value of the residual liquid is high, the COD value is also high, and the burden of sewage treatment is heavy ; High temperature and high pH damage fibers and affect the feel.
The traditional alkali scouring process: alkali boiling→hot washing→hot washing→cold washing→dyeing→alkali oxygen→hot washing→hot washing→cold washing→dyeing. Using pectinase scouring uses pectinase to selectively disperse pectin on cotton fibers; the decomposition of pectin helps to remove wax and other impurities during subsequent extraction/emulsification; maximizes fiber strength , soft to the touch.
Pectinase scouring process: enzyme cooking → dyeing. The traditional alkali process has pH>11, working temperature of 95-100℃, working time of 90-120min, general cloth effect, rough hand feeling, uniform dyeing, and weight loss of 4%-10%. Enzyme process pH 7.5～8.5, working temperature 50～60℃, working time 30min, cloth surface is clean, texture is clear, fabric is slightly thin, fluffy, smooth and elastic, dyeing uniform color yield 10%～15%, weight loss <1.5 %. The scouring cost of the traditional alkali process (taking knitted fabric as an example, the liquor ratio is 1:10, calculated on the basis of 100 kg of fabric) has a total energy cost of 100 and a total cost of 135, while the enzyme process scouring cost has a total energy cost of 17 and a total cost of 67.
The pectin in the cotton fiber exists between the wax and the fiber, which increases the binding force between the wax and the fiber. Removing the pectin reduces the binding force between the wax and the fiber, which is conducive to the removal of the wax. Pectinase is mainly used to replace the alkali agent used in cotton fabric scouring. Using pectinase alone to scour cotton fabrics, the removal rate of impurities is relatively low, especially the ability to remove impurities such as residual leaf stem chips and cottonseed husks is poor, and the whiteness and gross effect of treated fabrics are not as good as alkali scouring.
From the perspective of production practice, it is difficult to achieve the desired effect by simply using pectinase, and it is basically impossible to completely remove the wax on the surface of cotton fibers. It is necessary to add non-ionic surfactants during the enzyme treatment to produce a synergistic effect on the removal of wax. Improve fabric hygroscopicity, and significantly reduce the amount of pectinase and treatment time. In the process of scouring, applying moderate mechanical agitation and selecting biological enzymes with good compatibility and synergy effect will improve the activity of the enzyme and the scouring efficiency.
There are research literatures that pectinase, amylase, lipase, cellulase, etc. have a good synergistic effect, which can realize one-bath desizing and scouring and one-bath biological polishing for desizing and scouring. There are also literatures that the combination of pectinase and cutinase can significantly improve the removal rate of cotton wax and the hydrophilicity of fabrics. Pectinase, amylase, lipase, cellulase and other biological enzymes scouring greatly reduce the toxicity of scouring sewage.
3 Protease suitable for silk, leather, wool, cotton fabrics, etc.
Proteases break down proteins into peptides, which are then hydrolyzed into amino acids by peptidases. The proteases secreted by microorganisms vary with different strains. For example, Bacillus subtilis secretes gelatinase and caseinase, which can hydrolyze gelatin and casein; Streptomyces fischeri secretes keratinase, which can hydrolyze animal hair, horn, and hoof keratin. .
Protease is the earliest textile biological enzyme product used in my country, and is used in conventional processes for industrial applications such as silk degumming, sand washing, leather depilation, and fur softening. The treatment of wool by protease is mainly to prevent felting, anti-pilling, improve gloss and low temperature dyeing. Proteases are also used in the desizing process of protein sizing materials. In addition, protease can be compounded with cellulase, pectinase, etc. for scouring processing of cotton fabrics.
4 Cellulase suitable for polishing and finishing of cotton fabrics
Cellulase is a multi-component enzyme system, and most of the cellulase used in the textile printing and dyeing industry are produced by the fungus of the genus Xylozyme. Cellobiohydrolase in cellulase is further divided into exocellulase (CHB I and CHB II) and endocellulase (also known as endoglucanase, which consists of at least five cellulase enzymes. EG I, EG II, EG III, EG IV, and EG V). In addition, there is -glucuronidase. These cellulases have a synergistic effect in the hydrolysis of cellulose.
Cellulase can effectively treat cellulosic fabrics (with acceptable strength damage), mainly used in the polishing of cotton fabrics (smooth finish) and the reclaiming of denim. Cellulases are used in detergents to enhance stain removal. The most important component of cellulase products is endonuclease, which plays a key role in biopolishing, stone grinding, washing, and finishing. According to reports, cellulase is compounded with other enzymes such as amylase, pectinase, protease, etc., and has remarkable effects on desizing and scouring of cotton fabrics. It is the most successful textile enzyme product currently used.
5 Catalase for the removal of hydrogen peroxide
Catalase is an oxidoreductase that catalyzes the decomposition of hydrogen peroxide into water and oxygen. It is mainly used to remove residual hydrogen peroxide after the bleaching process, improve subsequent dyeing performance and quality, and there is no danger of excess. Catalase can also be used in the oxygen bleaching biological purification treatment of yarn dyeing machines, overflow jet dyeing machines, capstan dyeing machines and jiggers.
The use of catalase to remove hydrogen peroxide has become a routine process. The molecular weight of catalase is very large, and hydrogen peroxide usually remains inside the fabric, so it is necessary to speed up the flow of the treatment liquid and accelerate the decomposition of hydrogen peroxide through appropriate mechanical agitation. Since catalase has no effect on reactive dyes, as long as the pH value of the solution treated with catalase is appropriate, dyes and auxiliaries can be directly added for dyeing.
The use of catalase biological purification treatment can generally save more than 75% of water, and can save 50% of dyeing preparation time. The water washing treatment requires no high temperature process, and the process is short, which can significantly reduce energy consumption, and the process is easy to control. The application of catalase to the hydrogen peroxide bleaching of cotton fabrics can not only remove the residual hydrogen peroxide on the fabrics, but also directly dye them, with the characteristics of high efficiency, energy saving and no pollution.
Using catalase to remove the residual hydrogen peroxide on the fabric can increase the dyeing depth of the fabric. Catalase can decompose five million hydrogen peroxide molecules per minute, and the decomposition temperature is low, which is conducive to saving energy. The optimum process conditions for catalase to remove residual hydrogen peroxide are: temperature 20℃, pH value 6-8, enzyme dosage 4ml, treatment for 5min.
6 Lysozyme for antibacterial finishing
Lysozyme is a kind of glucosidase with strong thermal stability (it is currently the most thermally resistant enzyme), and its optimum pH range is 5.3 to 6.4. Lysozyme can resist not only Gram-positive bacteria, but also some negative bacteria, with broad antibacterial spectrum, low production cost and high safety. The antibacterial properties and durability of lysozyme have been practiced on wool and cotton fabrics, and it has high application value in the antibacterial finishing of textiles. As a natural anti-infective substance with bactericidal effect, lysozyme has the characteristic functions of antibacterial, reducing swelling and accelerating tissue recovery, so it is more used in human skin care.
7 Lipases for pre-dyeing of silk cotton fabrics and furs
Lipase can hydrolyze fat into glycerol and fatty acid, and the fatty acid is further oxidized to generate acetyl COA (N-cyclohexyl octylamine), which enters the TCA (tricarboxylic acid) ring, and is completely oxidized or enters glyoxylic acid to synthesize sugar.
Lipase is an enzyme that decomposes natural oils. It is mainly used in the textile dyeing and finishing industry for the pretreatment of silk and cotton fabrics and the pretreatment of fur dyeing. It can also treat polyester fabrics to improve the hydrophilicity of polyester fabrics. Such as: used for degreasing of silk spinning raw materials; used as a builder in wool scouring, which can remove wool epigenetic impurities, grease wax, and make wool spinnable; refining cotton fabrics can effectively remove cotton The polyester wax can be treated to improve the hydrophilicity of the polyester surface. Laundry powder with added lipase can remove the oil of neckline and cuff very well. Lipase can be used as an additive in detergents, significantly improving the wash removal of adhering oils and fats from garments.
8 Laccase for denim decolorization and rejuvenation
Laccase is an oxidoreductase. Laccase can catalyze the oxidation reaction of most dyes, resulting in decolorization or lightening of dyes. After testing, about 15 kinds of dyes out of more than 300 kinds of dyes in common use can be basically decolorized or lightened after being treated with laccase, and nearly 210 kinds of dyes can be modified by laccase catalyzed oxidation. Laccase especially has high decomposition efficiency for indigo dye, which is very suitable for decolorization and old-fashioning of denim.
It is said that the use of laccase and cellulase to decolorize denim in the same bath can make the surface of the fabric smooth and clean, while the treatment solution is basically colorless, and the enzyme is still active after 3 consecutive treatments, and the The process has little damage to the fabric strength, short processing time, easy process control, good reproducibility, the fabric surface is flat and thick, the surface is smooth and smooth, and the color is bright and elegant. Laccase is mainly used for decolorization and old-fashioning finishing of denim, and also for degumming of hemp fibers.
9 Application of new enzymes in textile printing and dyeing
The status of chemical synthetic fibers and pulp in textiles is obvious. These high molecular polymers cannot be biodegraded and degraded, causing environmental pollution. At present, researchers are studying new enzyme species, by screening bacteria with certain functions. It can be genetically modified to become high-performance enzyme products, or genetically engineered bacteria can be produced through transgenic to produce new enzyme species, or new enzyme products can be synthesized according to chemical biological structure and enzymatic principles.
These new enzyme products become imitation enzymes. The enzyme products that have been successfully developed in the laboratory include PVA degrading enzymes, polyester degrading enzymes, and genetically engineered enzymes for degrading nylon. PVA sizing has excellent sizing performance. If the industrially produced PVA degrading enzyme has high activity, it can not only realize the enzymatic desizing of fabrics containing a high proportion of PVA sizing, but also greatly reduce the amount of wastewater treatment, which is beneficial to the dyeing and finishing industry. The clean production of PVA is of great practical significance, and the application potential of PVA-degrading enzymes in the dyeing and finishing industry is great.
However, microorganisms that can degrade PVA are rarely distributed in nature, and it is difficult to extract PVA-degrading enzymes. It is very difficult to completely degrade PVA by a single microorganism, and it is necessary to mix strains to achieve the complete degradation of this polymer. At present, it is mainly to cultivate strains with high yield and high catalytic efficiency and reduce the production cost of enzyme products, which is also the key to whether PVA degrading enzymes can be industrialized.
Many impurities on natural fibers (high carbon number hydrocarbons, such as hemicellulose, cottonseed hull lignin, PVA pulp and cotton wax, etc.) still lack corresponding industrial enzyme products to effectively decompose them. Natural cellulose fibers contain hemicellulose and lignin, especially hemp fibers. Hemicellulose and lignin, if not removed, will greatly affect the spinnability of fibers. Most of hemicellulose and lignin can be removed by hemicellulase and ligninase treatment, but hemicellulase and ligninase have not been used alone in textile printing and dyeing processes, mainly with other enzymatic products (such as pectin) enzyme, cellulase, etc.) for fiber treatment.
The application of other new enzymes such as cutinase and keratinase in textile printing, dyeing and finishing is still under research. The one-bath treatment of wool with a compound product of keratinase and protease has obvious degradation effect on wool scale protein. After treatment, the wool scale has been basically peeled off, and the felt shrinkage rate of the fabric meets the requirements. At the same time, the dyeing rate is also improved. The amount is large, and the color depth of the fabric surface decreases after dyeing.