Fabric acid-proof finishing
Fabric acid-proof finishing
1. Principles of acid-proof finishing
Acid-proof finishing of textiles is a type of product for protective textiles. It is designed to protect the safety of the human body. The degree of acidic liquid penetrating through the fabric determines the acid-proof performance.
The principle of acid-proofing is similar to that of waterproofing and oil-repelling. Generally, acid liquid uses water as the medium, and its surface tension is greater than the surface tension of water. Therefore, acid-proof, waterproof, and oil-repellent finishing all change the surface properties of the fiber, reduce its critical surface tension, increase the contact angle, and make the liquid appear in a bead shape on the surface of the fabric to prevent the surface of the fabric from being wetted, moistened, and penetrated. , and prevent the capillary effect to achieve acid-proof, water-repellent and oil-repellent purposes.
2. Methods of acid-proof finishing
There are mainly the following methods for acid-proof finishing, most of which are aimed at the effects of strong inorganic acids on cotton fabrics.
1. Modification finishing method
Cotton fiber does not contain NH2 genes. Studies have shown that when cotton fibers contain a certain amount of NH2 genes, the acid corrosion resistance is improved. Therefore, we can join NH2-containing compounds with cotton fibers to obtain a certain acid resistance. We put This type of compound is called an acid-proof finishing agent, and this finishing method is called a modified finishing method.
Most of the modified finishing agents are polymer compounds containing NH2 genes. Copolymers such as styrene, acrylonitrile, and acrylamide are common. The copolymers contain active genes that can react with OH on cotton fibers. Not only can they graft NH2 genes The technology is applied to the cotton fiber and a layer of polymer film is formed on the surface of the fiber. Thus achieving acid resistance. For example, the copolymer of styrene and N-methylol acrylamide is used to finish cotton fabrics to make it have certain acid resistance and acid corrosion resistance; the polymerization of fluorine-containing acrylate, styrene and N-methylol acrylamide is used The cotton fabric is treated with acid-proof, waterproof and alkali-proof finishing; the silk fabric is graft-modified with fluorine-containing acrylate monomers (hexafluorobutyl acrylate, dodecafluoroheptyl methacrylate). The greater the grafting rate, the The denser and more uniform the fluoride layer formed on the fiber noodles is, the higher the water repellency and alkali resistance will be.
2. Surface treatment method
This method is the same as general waterproofing. It is to waterproof the surface of the fabric and reduce the surface tension of the fabric, thereby preventing the penetration of acidic liquids and reducing the absorption of acidic liquids by the fabric. The finishing agents used (such as coating agents, organic fluorine, silicone surface finishing agents) are generally acid-resistant. For example, use silicone EGE-2 waterproofing agent to treat various textiles such as cotton, rayon, wool and polyester to make them have good water repellency and acid resistance; use fluorine-containing emulsions LFM-3 and LFM-H Finishing polyester and rayon fabrics can significantly reduce the surface energy of the fabrics and significantly improve the acid, water and oil repellent properties of the fabrics; use organic fluorine waterproofing agent AG710 to perform acid-proof treatment on polyester elastic yarn and tussah silk mixed-twisted fabrics , an acid-proof silk with relative resistance to washing was prepared.
Organofluorine finishing technology should be widely used in acid-proof surface finishing of textiles. The chemical bonds connecting the fluorine atom skeleton layers in the outer layer of organic fluorine are neatly and densely arranged and stretched outward under the action of high-temperature baking, forming a strong protective film on the surface of the fabric, giving the fabric excellent acid repellency and acid pressure resistance. It can protect the original feel, breathability and color. The disadvantage is that after washing, clothing must be baked or ironed at high temperatures to restore its protective properties. At present, new finishing agents can make the outer layer of fluorine atoms in the organic film on the fabric surface have less recovery energy to stand back up. After washing, the fabric only needs to be dried to restore the protective effect.
3. Composite finishing of organic fluorine and coating
Although fabrics using modified finishing methods and surface treatments have certain acid-proof and acid-repellent properties, it is difficult to form a continuous protective film on the surface of the fabric and has poor acid penetration resistance. Therefore, in recent years, the method of combining organic fluorine treatment with coating finishing has been mostly used to completely solve the problem of acid adhesion and penetration. Acid-resistant coatings generally use polyacrylate, polyurethane and polytetrafluoroethylene reagents, etc., and form a film through high temperature to form an acid-proof protective layer with a barrier effect, thereby greatly improving the acid penetration resistance of the fabric. For example, a special anti-acid agent and a polyacrylate coating blend are used to coat the fabric, and a fluorine-containing waterproof and oil-proof finishing agent B is used to water-repellent the fabric, and a durable acid-proof, alkali-proof and moisture-permeable product is developed. Coated cloth; use polyacrylic or polyurethane resin for moisture-permeable coating finishing, and then use fluorine-containing acid-proofing agent (DS-106 and DS-107) for surface finishing to completely prevent acid from directly contacting the fiber and penetrating into the fiber. Inside the fiber; use polyurethane coating agent HCP-10 to coat and finish the pure cotton fabric, and then use three-proof finishing agent HCP-1 to finish the surface, finally achieving breathable (wet), acid-proof, alkali-proof, water-repellent and Oil-resistant cotton fabric.
4. Acid-proof multi-functional finishing
If acid-proof fabrics are waterproof, oil-proof, anti-static, flame-retardant and radiation-proof, they can provide more comprehensive safety protection. Research in this area has now been carried out. For example, adding fluorocarbons during the anti-shrink and flame-retardant finishing process of wool can give wool multiple functions such as water repellency, oil repellency and protection against hazardous chemicals, so it can be used to prepare multi-functional protective clothing; the TyChemF protective clothing produced by DuPont in the United States uses DuPont Tyvek non-woven fabric is compounded with the chemical company’s Saranex23-P protective film, which has super chemical resistance.�Extent of fabric.
The British Occupational Health Organization has developed a method for measuring harmful liquids. It uses the theory of electrochemistry to design a standard battery. The time and speed of acidic liquid penetrating the fabric can be measured through the medium on both sides of the fabric. This method is relatively scientific. In short. There are many methods for measuring harmful liquids, each with its own advantages and disadvantages. As the technology in this area continues to mature and improve, its testing methods and instruments will become more scientific and perfect.
Our country currently uses the GB12012-89 “Acid-proof Work Clothing” standard for acid penetration, acid rejection, and acid pressure resistance performance testing.
6. Development trend of acid-proof finishing
1. Research and develop new acid-resistant fibers
From the perspectives of environmental protection, human safety and protective effects, the development of high-performance, environmentally friendly acid-proof fibers is one of the future development trends. The development of new acid-resistant fibers must not only consider their acid-resistant stability, but also take into account the fiber’s preventability and heat and moisture comfort. The development of acid-resistant stable fibers can be produced by modifying fibers or developing new fibers. JinJS et al. used polyurethane urea and silane coupling agent to prepare polyurethane fibers, and then intertwined them with natural fibers. The resulting interwoven fabric has good acid-repellent properties.
2. The unity of versatility and comfort
Acid-proof fabrics are an important category of protective textiles. However, because the hazards faced in actual working environments are often complex and unpredictable, acid-proof, alkali-proof, waterproof, oil-proof, flame-retardant and anti-static fabrics have been developed. Multifunctional clothing fabrics are of great significance. In addition, while emphasizing the multi-functionality of acid-proof clothing, it should also be comfortable and safe to wear, which is an important requirement for the development of protective fabrics.
3. Develop new energy-saving, environmentally friendly and acid-proof finishing agents
Organic fluorine is currently the most popular anti-acid finishing agent. However, due to its high price, high baking temperature, and potential threat to the environment, the finished fabric must be baked or ironed at high temperature after washing to restore its properties. Protective performance, so promotion and application are limited. At present, the development of low-cost, energy-saving and environmentally friendly, healthy, comfortable, safe and non-toxic durable acid-proof fabric finishing agents to replace the banned fluorine-containing finishing agents has attracted more and more attention.
4. New finishing technology
In recent years, some new energy-saving and environmentally friendly finishing technologies have been introduced, such as plasma technology and nanotechnology. Plasma technology can improve the surface properties of fibers. Some people use gases such as CF4 and C3F6 as the plasma treatment atmosphere to give fabrics such as nylon and cotton certain water- and oil-repellent properties. Nanotechnology can use low surface energy fabrics to open up a new way for acid-proof, water-repellent and oil-repellent finishing of textiles.
Test methods
1)Measurement method of acid repellency
GB12012-1989 is used for acid penetration resistance, acid rejection, and acid pressure resistance performance testing.
2)Measurement method of oil repellency
AATCC test method ll8-1989 is adopted, and the specified liquid No. 1, 2, 3, 4, 5, and 6 are used to measure the fabric, and the surface tension is determined according to the penetration of various liquids. Generally, if Liquid No. 4 does not penetrate the fabric within 30 seconds, the fabric is oil-repellent. If Liquid No. 6 does not penetrate the fabric, the oil-repellent effect is good.
3)Measurement method of water repellency
AATCC test method 22-1989 is used for the spray test. According to the water droplets or water shapes on the tested fabric, it can be rated as six levels: 0, 50, 70, 80, 90, and 100.
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