Waterproof and breathable composite fabric
Waterproof and breathable composite fabric
What is waterproof and breathable functional fabric? When you go hiking, it may rain unexpectedly, so you can’t go up the mountain with an umbrella. Mountain climbing is also a very physically demanding sport and requires a lot of sweating. The temperature on the mountain is usually very low, so you can’t take off your clothes. So, how can we solve this kind of problem at once? In fact, people have been studying this issue for a long time, that is, wearing clothes that are both waterproof and breathable. (People often call it breathable fabric, but it is not the gas in the air, but the steam evaporated from sweat).
Specifically, waterproof and breathable fabrics mean that water does not penetrate into the fabric under a certain pressure, but the sweat emitted by the human body can be transmitted to the outside world in the form of water vapor through the fabric, thereby preventing sweat from accumulating and condensing between the body surface and the fabric. Maintaining the comfort of clothing, it is a high-tech, unique functional fabric. Waterproofing is not a problem for ordinary fabric workers. The key is how to achieve moisture permeability.
1. Moisture permeability through fiber
1. Ventel fabric. The earliest waterproof and breathable fabric is the famous Ventile fabric. It was designed by the British Shirley Research Institute in the 1940s. It uses high-count, low-twist pure cotton yarn from Egyptian long-staple cotton and high-density heavy-weight flat weave fabric. It was initially mainly used for cold protection for British Air Force pilots during the Second World War. Soak. When the fabric is dry, the gaps between the warp and weft yarns are larger, about 10 microns, which can provide a highly moisture-permeable structure; when rain or water hits the fabric, the cotton yarns expand, reducing the gaps between the yarns to 3 to 4 microns. This closed-cell mechanism is combined with a special water-repellent finish to ensure that the fabric is not further penetrated by rainwater. At present, this type of fabric has long been replaced by other waterproof and breathable fabrics.
2. Coolmax fabrics. Major international companies such as DuPont and Japan’s Toray have researched the method of creating pores inside the fiber to discharge sweat from the body, which is the moisture-absorbing and sweat-wicking fabric on the market. The production technology of this type of fiber is concentrated in the hands of such large international companies, and the price is relatively high, making it difficult to become the mainstream of the market.
2. Achieve moisture permeability through coating
Using dry direct coating, transfer coating, foam coating, phase inversion or wet coating (solidified coating) and other process technologies, various coating agents with waterproof and moisture-permeable functions are applied to the fabric. On the surface of the fabric, the pores on the surface of the fabric are closed or reduced to a certain extent by the coating agent, thereby obtaining waterproofness. The moisture permeability of fabrics is determined by the microporous structure formed by a special method on the coating or the interaction between the hydrophilic groups in the coating agent and water molecules. With the help of hydrogen bonds and other intermolecular forces, water molecules are adsorbed on the high-humidity side, and then Pass to the low temperature side to obtain the analytical action. Coated fabrics are widely used because they are low in price and achieve a certain degree of moisture permeability. However, due to its poor waterproof and breathable performance and unsatisfactory feel, its market share is gradually decreasing.
The wet transfer coating fabrics developed now bring new opportunities to coated fabrics. Not only do they have high physical properties such as waterproofing and moisture permeability, the surface fabric can be treated with 100% Teflon, and its washing fastness can reach 25 times. Above, the hand feel is also very good.
3. Achieve moisture permeability by laminating waterproof and moisture-permeable membrane
1. PTFE film
The diameter of water vapor molecules is 0.0004 microns, while the diameter of small mist in rainwater is 20 microns, and the diameter of drizzle is already as high as 400 microns. If you can create a film with a pore diameter between water vapor and rainwater, it will be waterproof Isn’t it possible to achieve moisture permeability? The American GORE company became the first company to produce this membrane using polytetrafluoroethylene (PTFE). It was laminated with fabric and named GORE-TEX. However, because PTFE is very chemically inert, there are few materials that can laminate it well with other fabrics, resulting in very poor fabric fastness. Later, after continuous efforts, it was combined with other hydrophilic film layers to form a composite film, and special treatment was performed on the film, so that the fastness was greatly improved. It is generally believed that the water pressure of Gore-Tex fabric can reach 10,000mm, and the water pressure will drop significantly after washing 6-7 times; the moisture permeability can reach 10,000g/sqm*24hrs, but this is not the case with just made fabrics. To reach this value, it takes several washings to remove part of the glue, increase the available pores, and increase the moisture permeability.
PTFE fabrics are now mainly represented by Gore and Donaldson in the United States. Gore produces and laminates its own films and does not sell films separately. It designates better clothing manufacturers to make clothing and has separate sales staff to cooperate with them. Donaldson only produces films and laminates them at Japanese laminating manufacturers. The competition between these two companies in the market is also very fierce. Domestic PTFE manufacturers are also gradually emerging, but they mainly use single-component PTFE films without compounding with hydrophilic films, and the washing fastness is generally only about five times. Last time I met an Indonesian manufacturer at the Shanghai Industrial Fabrics Exhibition, it was said that the products were washed about five times.
Although PTFE fabric has better waterproof and breathable properties than other fabrics, due to its chemical inertness, the film is difficult to be degraded by nature, and its combustion temperature is as high as 405°C. Large-scale application has gradually made GORE-TEX an environmental killer. Faced with such problems, GORE established what it callsBalance the project’s waste clothing recycling mechanism in order to reduce its impact on the environment. I hope that GORE can continue to move forward firmly as environmentalism becomes more and more popular.
The clothing production process uses manual methods to sew and assemble the fabrics of the clothes according to the template. With the development of bonding technology, hot melt adhesive film lamination is gradually used, and bonding replaces traditional stitching. The clothing technology has set off new changes. The interlining of clothing plays a role in reinforcing and shaping the clothing, and is an indispensable auxiliary material for clothing production.
Hot melt adhesive film lamination is an interlining that is evenly bonded with hot melt adhesive on the base fabric (non-woven fabric or cotton woven fabric). After the fabrics of the collar, placket, front and rear panels of the garment are pressed and bonded, the garment becomes It becomes curved, crisp, wrinkle-free, shapeless, elastic, durable, beautiful to wear, light and comfortable. It can also reduce the cost, improve the grade, simplify the process and improve the production efficiency, which is of high value.
In addition to clothing, hot melt adhesive film lamination is also used in shoes and hats, leather, decoration and other departments. In the leather industry, hot-melt adhesive film composite cloth is used to bond the fur or leather bottom plate with the lining cloth, and then cut into garment pieces to improve the shape retention performance. Hot melt adhesive film composite cloth is used in leather decoration products and in the leather bag and handbag industry to play a stiffening and filling role. In the shoe and hat industry, low-cost hot-melt adhesive film composite fabrics with non-woven fabrics as the base fabric are used for middle pads, uppers, hat brim, heel pads and other parts. During use, the lining cloth is bonded to the hat material and shoe material, and then cut. The interlining acts as a stiffener.
Although hot melt adhesive film composite fabric is used as clothing lining, its quality requirements are stricter than fabrics in some aspects. The reason is very simple, because the quality problem of a small piece of interlining can greatly affect the use value of a piece of clothing. Hot-melt adhesive film composite fabric is a textile. In addition to general appearance quality inspection, special emphasis is placed on the requirements for its intrinsic quality and wearing performance to ensure the use value of the finished clothing. yZGhYImG
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