Why do functional fabrics not only breathe moisture but also waterproof?
The main principle that fabrics can be waterproof, but also moisture permeability is based on the different state of the water material has a different diameter, resulting in the possibility of its spread.
Wet can be understood as "water vapor", which refers to the "moisture" formed by the human body. In the state of water vapor, the water particles are very fine, and according to the principle of capillary motion, they can penetrate to the other side of the capillary smoothly, and thus the phenomenon of moisture permeability occurs. When water vapor condenses into water droplets, the particles become larger. Due to the surface tension of the water droplets (water molecules “pull and pull†against each other), water molecules cannot smoothly separate from the water droplets and penetrate to the other side. The penetration of water occurs, and it also has a waterproof function.
Extended reading:
Water-proof and moisture-permeable fabric means that water does not dive into the fabric under a certain pressure, but the sweat emitted by the human body can be transmitted to the outside through the fabric in the form of water vapor, thereby avoiding the accumulation of sweat condensing between the body surface and the fabric, so as to maintain the clothing Comfort, it is a high-tech, unique functional fabric. The most widely used current practice is to achieve waterproof and moisture permeability by coating or waterproof and moisture permeability by laminating a waterproof and moisture permeable film . In addition, the gas molecules are generally around 0.3 nm, which is much smaller than the diameter of the water droplets. The waterproof and moisture-permeable fabrics will have a certain permeability. Below, we take a closer look at the type of waterproof and breathable fabric.
First, through the fiber to achieve moisture permeability
1, Wen Taier fabrics. The earliest waterproof and breathable fabric was the famous Ventile fabric. It was designed in the 1940s by the British Shirley Institute. The high-density, low-twist cotton yarn high-density heavy-weight tissue fabrics made from Egyptian long-staple cotton were originally used in the cold prevention of British Air Force pilots during the Second World War. Anti-impregnated clothing. When the fabric is dry, the gap between the warp and weft yarns is large, about 10 microns, which can provide a highly moisture permeable structure; when the rain or water is poured on the fabric, the cotton yarn expands, so that the gap between the yarns is reduced to 3 to 4 microns. This closed-cell mechanism, combined with special water repellent finishes, ensures that fabrics are not further penetrated by rain. At present, this type of fabric has long been replaced by other waterproof and breathable fabrics.
2, Coolmax fabrics. DuPont, Japan's Toray and other major international companies have studied how to create sweat through the inside of the fiber to excrete sweat, which is the moisture wicking fabric on the market. This type of fiber production technology is concentrated in the hands of such large international companies, the relatively high price, it is difficult to become the mainstream of the market.
Second, through the coating to achieve moisture permeability
A variety of water- and moisture-permeable coating agents are applied to fabrics using processes such as dry direct coating, transfer coating, foam coating, phase inversion or wet coating (solidification coating). On the surface, the pores on the surface of the fabric are closed or reduced to a certain degree by the coating agent, so that water repellency is obtained. The moisture permeability of the fabric is determined by the hydrophilic structure of the microporous structure or coating agent formed on the coating layer and the water molecules, and by means of hydrogen bonds and other intermolecular forces, the water molecules are adsorbed on the high humidity side. Transmitted to the lower temperature side of the analytical effect to get. The coated fabric is low in price and achieves a certain degree of moisture permeability and is widely used. However, due to poor waterproof and moisture permeability, the hand feel is not satisfactory, and the market share is gradually reduced.
The wet transfer coating fabric developed now makes the coated fabric rejuvenated. It not only has a very high physical and water resistance index such as waterproof and moisture permeability, but also the fabric can be treated with 100% Teflon. The washing fastness can reach 25 times. Above, I feel very good.
Third, through the laminated waterproof and moisture permeable membrane to achieve moisture permeability
1, PTFE film
The diameter of water vapor molecules is 0.0004 microns, and the diameter of the smallest mist in rainwater is 20 microns. The diameter of drizzle is up to 400 microns. If you can make a film with a pore diameter between water vapor and rain, then it is waterproof. Isn't it wet enough to achieve it? U.S. GORE Corporation made use of polytetrafluoroethylene (PTFE) as the first company to produce the film. After the composite lamination with the fabric, the brand name was GORE-TEX. However, since PTFE has a very strong chemical inertness, there is almost no material that can laminate it well with other fabrics. The first generation fabrics have very poor fastness. Later, through continuous efforts, it became a composite film by sublimating together with other hydrophilic thin film layers and performing special treatment on the film, greatly improving the fastness. It is generally believed that the water pressure of Gore-Tex fabric can reach 10000mm, and the water pressure only drops after 6-7 times of water washing; the maximum moisture permeability can reach 10000g/sqm*24hrs, but this is not the fabric that can be just made To reach this value, it needs to be washed several times, and part of the glue will be washed off. The available pores will increase and the moisture permeability will increase.
PTFE fabrics are currently represented mainly by Gore and Donaldson of the United States. Gore produces its own thin film and composites, does not sell the film separately, assigns a better clothing manufacturer to make clothing, and has a single salesperson to coordinate with. Donaldson only produces films and composites at compound manufacturers in Japan. The competition between the two companies in the market is also very fierce. Domestic PTFE manufacturers have also gradually emerged, but they are mainly composed of single-component PTFE membranes. They are not compounded with hydrophilic membranes, and the washing fastness is generally only about five times. The last time I met an Indonesian manufacturer at the Industrial Fabrics Exhibition in Shanghai, it was allegedly washed about five times.
Although waterproof and moisture-permeable properties of PTFE fabric are superior to other fabrics, but due to its chemical inertness, the film is difficult to be degraded by the natural world. The combustion temperature is as high as 405°C. Large-scale application makes GORE-TEX gradually become the killer of the environment. In the face of such difficulties, GORE has established a waste clothing recycling mechanism called balance engineering in order to reduce its impact on the environment. It is hoped that GORE will be able to walk steadily as environmental protectionism continues today.
2, TPU film
TPU is an abbreviation of thermoplastic polyurethane film and belongs to a non-porous hydrophilic film. Since the film itself has no pores, the waterproof effect is naturally good, and at the same time, it also makes the fabric windproof and warm. The moisture permeability is mainly achieved through its hydrophilic characteristics, and the steam is transferred from a place with high pressure to a low place depending on the difference in vapor pressure inside and outside the clothes, thereby achieving the function of moisture permeability.
For more content, please follow this site
Silicone Free Defoamer,Defoaming Agent,Anti Foaming Agent,Natural Defoaming Agent
NINGBO LUCKY CHEMICAL INDUSTRY CO., LTD , https://www.chinaluckychem.com