Silk is one of the comfortable and high-end fabrics used as underwear and shirts. The amino acid residues of its protein peptide chain have moderate antibacterial properties, and it is also a hygienic textile fabric. However, since silk itself is protein fiber, it is a good food for mold and bacteria. When the relative humidity is above 85, the temperature is between 5 and 50°C, and the pH value is below 5, mold can easily breed on silk fibers, and bacteria can easily grow when the pH value is above 6. When real silk contains a lot of water, or when there is a lot of residual sericin, soap, oil or starch slurry left after refining, mold and bacteria can easily breed under hot and humid conditions, causing protein fiber degradation and chain breakage, and strong damage.
There are many types of mold that can cause mold on silk fabrics, such as Aspergillus niger, Penicillium citrinum, Penicillium griseus, Cladosporium, Aspergillus, Crescentus, Gliomyces, Neurospora, Trichoderma, etc. Ten kinds. When Aspergillus niger grows on silk fabrics, its spore clumps are black, causing the silk fibers to be stained black, while Penicillium citrinum is yellow, Penicillium griseus is green, Cladosporium spp. is brown, etc. During the metabolism of mold, mold will produce ethylene glycol, citric acid, oxalic acid, lactic acid, acetic acid, etc., thereby producing odor, causing the temperature of the fabric to rise, the luster to decrease, and mildew spots to appear. Therefore, during the storage, transportation, and sale of dyed fabrics, During the pre-storage process, in order to prevent mold, a bactericidal and anti-fungal agent must be added to prevent mold from growing.
There are dozens of bacteria that easily breed on silk fibers, such as Staphylococcus aureus, Escherichia coli, Enteritidis, Pseudomonas aeruginosa, Trichophyton mold, Trichophyton rubrum, etc. Some of these bacteria on silk fabrics come from polluted environments. , and some are caused by illness or skin infection during use. Therefore, after being treated with antibacterial and antifungal agents, silk textiles can have more medical and hygienic functions.
Antibacterial and anti-mildew technology for silk textiles
Process control during scouring and dyeing
In view of the high temperature and humidity in the silk refining and dyeing workshops, the oleic acid soap used for silk refining and certain additives applied to the silk during the dyeing and finishing process, such as plasticizers, oils, pigments, etc., will degrade under appropriate hot and humid conditions. Causes mildew. The anti-mildew measures taken by Japanese silk printing and dyeing factories include:
After scouring, dyeing and finishing, the water produced from the silk should be clear.
Keep the operating environment of the refining, dyeing and finishing workshops clean and tidy.
A certain amount of antifungal agent is added during silk processing.
The silk after printing and dyeing must be fully dried and cooled before being packaged.
Fiber surface modification
Acetylation and cyanoethylation of silk fiber make it unable to become feed for mold. The method of cyanoethylation of silk is: immersing in 0.1% to 1% aqueous solution of sodium hydroxide or sodium cyanide, or reacting with acrylonitrile using the gas phase method. This technology uses a chemical reaction to attach antibacterial groups to the silk fiber, so that the silk fiber can obtain a permanent antibacterial effect. However, this method has high requirements for antibacterial groups and the mR technology is relatively complex, so it is not widely used yet.
Chitosan is prepared into an acetic acid solution of a certain concentration to serve as an antibacterial finishing agent. The two-dip and two-padding method (padding rate 100) is used to finish the silk nonwoven fabric. After finishing, the silk nonwoven fabric has obvious antibacterial properties against Staphylococcus aureus and Escherichia coli, but has low antibacterial properties against Candida albicans. It has good washing resistance and does not need to add additional cross-linking agents, thereby avoiding the need for cross-linking agents. The effect of adding on the feel of nonwoven fabrics. The antibacterial mechanism of chitosan is mainly that the quaternized amino cations in the chitosan molecule can adsorb bacteria. It can combine with anions on the surface of the bacterial cell wall to hinder bacterial growth and synthesis and denature it; at the same time, the chitosan molecular chain The glucoside bond is broken, preventing the transfer of materials inside and outside the bacterial cell wall, thereby damaging the metabolism, respiration and material transport functions of the bacteria, causing them to lose their survival conditions, causing the internal tissues of the bacteria to be exposed and die.
According to reports, antibacterial conductive silk fibers can be prepared by reacting copper compounds and sulfur-containing reducing agents. The preparation process is: silk fiber-copper compound-sulfur-containing reducing agent treatment-crystallization-antibacterial conductive fibers. X-ray diffraction scanning electron microscopy analysis proves that the surface of the silk fiber is covered with a continuous and evenly distributed CuS antibacterial conductive layer. Research results show that the treated silk fiber has an antibacterial rate of 98% against Escherichia coli, Staphylococcus aureus, and Candida albicans, and after 20 times of washing, the fabric still has a high antibacterial rate. This is because A certain amount of copper compounds are firmly bound to the silk fiber. After testing with an atomic spectrophotometer, the copper ion concentration on the fiber is 3.13×10-4mol/g; the volume specific resistance PV dropped from 9.2×109Ω·cm to 57.6Ω·cm. Moreover, the washing resistance is good. After 20 times of washing, the PV does not increase much and is still of the same order of magnitude. Therefore, the silk fiber prepared according to this method not only has excellent antibacterial properties, but also has good electrical conductivity.
Silk fibroin fibers treated with tannic acid are reacted in a silver (I) aqueous solution and a solution of zinc (II), copper (II), and nickel (II) ammonia complexes to prepare metal-complexed silk fibroin fibers. Staphylococcus aureus and Klebsiella have strong bactericidal effects. Its preparation method is:
Preparation of silk fibroin fiber: remove the pupae from the fresh cocoons of silkworms, dry the cocoon layer in a desiccator, and then use 0.5% (mass concentration, the same below) mercerized soap solution.Refining. Then add Na2CO3 with a concentration of 0.05%. Soak in the solution for 10 minutes, take it out and wash it with distilled water. After drying, extract the waxy material in diethyl ether for 48 hours to obtain pure silk fibroin.
Silk fibroin fiber tannic acid treatment: Silk fibroin and 4.76 tannic acid solution are soaked for 2 hours at a bath ratio of 100:1 and a solution temperature of 7O°C. Take out the silk fibroin fibers and dry them. The adsorption rate of silk fibroin fibers to tannic acid is 25.14%.
Metal complexes are introduced into silk fibroin fibers using Cu(NO3)2·H2O, AgNO3, Ni(NO3)2·6H2O, and Zn(NO3)2·6H2O to prepare various 0.02M aqueous solutions and 0.02M metal complexes. compound solution. Then add the corresponding KNO3 according to the ion concentration of the solution, and the amount added is corresponding to 0.1M plus 2M KNO3. Tannic acid-treated silk fibroin fibers were immersed in the above solution with a liquor ratio of 100:1 and a temperature of 25°C. After shaking for 24 hours, wash with distilled water and methanol and then dry in vacuum. Experimental results show that when untreated silk fibroin fibers react in an aqueous solution of copper (II), zinc (II), and nickel (II) ammonia complexes, the planar metal silk fibroin complex obtained has no antibacterial properties; Complex immobilized fibers obtained by dipping silk fibroin fibers treated with tannic acid in a silver (I) aqueous solution with a low pH value, although the introduction of metal ions is low, shows strong resistance to Staphylococcus aureus and Gram-negative bacteria. Lactobacillus has strong bactericidal properties; silk fibroin fiber treated with tannic acid, metal complex fiber prepared in an aqueous solution of copper (Ⅱ), zinc (Ⅱ), nickel (1I) ammonia complex, Due to the formation of planar metal tannic acid complexes that are firmly combined with silk fibroin fibers, they have strong bactericidal properties against Staphylococcus aureus and Klebsiella pneumoniae. According to the data, silk fabrics treated with tannic acid have a higher absorption of Ag and form an extremely stable silk-tannic acid-Ag complex, showing good antibacterial properties.
The silk fiber is immersed in the dye solution, and the dye molecules are adsorbed on the fiber through intermolecular forces such as hydrogen bonds, dipole forces, and dispersion forces, and then solidified in a solution containing copper (II) ions. Coordinated and fixed, after washing and drying, functional silk fibers and fabrics are prepared, which have excellent antibacterial properties. This is the result of the synergistic effect of dye molecules. It still maintains good antibacterial properties after 50 times of washing, which can meet practical requirements.
Cover the silk fiber with a barrier so that mold cannot come into contact with the fiber
For example, adding 2% to 3% (based on solution volume) acetic acid to the trimethylol melamine solution makes it an insoluble polymer, and then adding 20% formic acid can become the formic acid colloid of methylol melamine. After silk fabric is finished, if it contains 10% to 12% resin, the anti-mildew effect will be very good.
After the silk is padded with potassium thiocyanate aqueous solution, it is then treated with a 1,2-epoxy-2,3-dichloropropane solution of carbon tetrachloride, and then washed and dried with carbon tetrachloride, acetone, and warm water in sequence. Dry for durable mildew resistance.
This silk anti-mold and anti-bacterial technology works by covering the silk fiber with a barrier so that microorganisms such as mold and bacteria cannot come into contact with the silk fiber. Although it does not kill microorganisms, it has a better anti-mold and anti-bacterial effect.
Anti-mildew and anti-bacterial measures during warehouse storage
Keep the warehouse environment dry, ventilated and clean.
When the silk is put into storage, check whether the package is damaged, whether it is damp on rainy days, or whether the moisture content of the packaging box is too high, etc.
Do not stack silk near walls, pillars, ditch edges, or place it in leaky areas to avoid direct sunlight.
The warehouse should be disinfected regularly, silk products that have been backlogged for a long time should be diligently maintained and turned, and first-in, first-out should be implemented.
Anti-mildew and antibacterial measures for home storage
After wearing the silk coat, brush it lightly and hang it in a ventilated place to eliminate moisture and sweat odor.
Silk containing oil soap, starch, etc. is prone to mold and should be washed before storage.
The active period of mold is mainly from April to October every year. Storage containers should be sealed to prevent mold. The room where the silk containers are stored should have good ventilation, low temperature, and small changes in temperature and humidity.
If you suspect that there is mold attached to silk clothing, you can soak it in hot water at about 60°C, iron it, dry it, and then store it.
Current status and development trends of anti-mildew and anti-bacterial technology for silk textiles
At present, anti-mildew and anti-bacterial technologies for textiles at home and abroad can be roughly divided into two types: (1) antibacterial fibers are first produced and then made into various types of anti-bacterial fabrics; (2) fabrics are post-processed with anti-mildew and anti-bacterial agents to obtain anti-bacterial fabrics. Mildew antibacterial properties. In comparison, the fabric obtained by the first method has long-lasting antibacterial effect and good washability, but it has high technical content, great difficulty, and covers a wide range of fields. The production process of antibacterial fiber is relatively complicated and requires high antibacterial agents. However, the second method has high requirements for antibacterial agents. The processing process is relatively simple, but there are many three wastes in production, and its washability and antibacterial effect are poor. Since the second method is easy to process and has a wide range of antibacterial agents to choose from, textiles, whether they are raw fibers, yarns or fabrics, or even ready-made garments, can obtain antibacterial effects through post-finishing methods. Therefore, various types of antibacterial agents currently on the market can Among fabrics, most are finished and processed later. However, according to the development trend, antibacterial fiber will definitely develop in the future. For natural fibers, it is difficult toThe antibacterial effect is obtained through fiber modification, so textiles made of natural fibers are still mainly post-processed. Therefore, silk textiles are mainly post-processed with anti-mildew and anti-bacterial agents to obtain anti-mildew and anti-bacterial properties. Currently, most of the antifungal and antibacterial agents on the market have problems such as poor antibacterial broad spectrum, poor washing resistance, and unreliable safety. The future development trend should be: use highly safe anti-mildew and anti-bacterial agents to treat silk fabrics, such as natural anti-mildew and anti-bacterial agents (such as chitosan, mandarin cypress, mugwort, amaranth, etc.) to treat silk fabrics; improve the anti-mildew and anti-bacterial properties The effect is washable, durable and broad-spectrum; developing in the direction of multi-functionality, such as anti-mildew and anti-bacterial processing and dyeing, flame retardant, soft finishing, resin finishing, waterproof and moisture-permeable finishing, anti-fouling and easy-wash finishing, and anti-UV finishing etc., thereby improving the added value and market competitiveness of silk and catering to the needs of consumers.
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