What is waterproof and permeable fabric? What is waterproof and permeable functional fabric?

What is waterproof and permeable fabric? What is waterproof and permeable functional fabric?
The measure of water proof is the water pressure height mm per square millimeter, which is measured by the weight of the water vapor for 24 hours per square millimeter.
Introduction of waterproof and moisture permeable functional fabric
When you go mountain climbing, it will rain, and you can't go up the mountain with an umbrella. Mountain climbing is also a very physical exercise, a lot of sweat, and the temperature in the mountain is generally very low, always can not take off the clothes bar. So, how can we solve these problems? In fact, people have been studying this problem very early, which is to wear a waterproof and moisture permeable garment. It is often referred to as a breathable fabric, but not a gas in the air, but a vaporized steam from the sweat.
Specifically, waterproof breathable fabric refers to water under certain pressure is not immersed in the fabric, and the human body can emit sweat in the form of water vapor transmission through the fabric to the outside world, so as to avoid the accumulation of sweat condensation in between the surface and the fabric to maintain the comfort of clothing, it is a function of high technology unique fabric. Waterproof for ordinary fabric workers is not a difficult problem, the key is how to realize the moisture. Next, we get a deep understanding of it from the types of waterproof and permeable fabrics.
1. Moisture permeation through fiber
1, Venter fabric. The earliest waterproof and moisture permeable fabric is the famous Venter (Ventile) fabric. It is the last century in 40s, designed by Shirley research in the UK, the Egyptian cotton high count and high density pure cotton yarn twist low heavy flat fabric, initially mainly used during the Second World War, the British Air Force pilots cold suit. When the fabric is dry, the warp yarn of the gap between the larger, about 10 microns, can provide highly permeable structure; when the rain or water fabric, cotton yarn expansion, the interstices between the yarns were reduced from 3 to 4 microns, the obturator mechanism with special water repellent combination, ensure fabric the rain was not further penetration. At present, this kind of fabric has already been replaced by other waterproof and moisture permeable fabrics. Dress collocation
2, Coolmax fabric. DuPont, Japan and Dongli and other large international companies studied the way of creating pores through fibers, which can drain sweat out of the body, that is, the moisture absorption and sweat perspiration fabric on the market. This kind of fiber production technology is concentrated in this kind of international big company hand, the price is relatively high, it is difficult to become the mainstream of the market.
Two. Through the coating to realize the moisture permeation
The direct dry coating, transfer coating, foam coating, phase inversion or wet coating (coating) technology, a variety of waterproof, moisture permeable coating agent is coated on the surface of the fabric, the fabric surface coating agent was closed or reduced to a certain extent, so as to get waterproof. The moisture permeability of fabrics is affected by the pore structure or the hydrophilic group in the coating agent and the water molecules. The water molecules are adsorbed on the high humidity side with hydrogen bonds and other intermolecular forces, and then pass to the low temperature side. The price of the coated fabric is low, it has realized a certain moisture permeable, and is widely used. However, because of its poor waterproof and moisture permeability, the feeling of hand can not be satisfactory, the market share is gradually decreasing.
Now the development of wet transfer coating fabrics and fabric coating makes the glow of the new machine, it is not only waterproof and moisture permeable property index is very high, the cloth can do 100% Teflon treatment, washing fastness can reach more than 25 times, feel is very good.
Three. Through the laminating waterproof and moisture permeable membrane to realize the moisture permeation
1, PTFE film
The water vapor molecule is 0.0004 microns in diameter, and the diameter of the rain water mist minimum diameter of 20 microns, the diameter of the drizzle has been as high as 400 microns, if can make the film pore diameters between water vapor and rain, so both waterproof and moisture can not be achieved? GORE, a company in the United States, used polytetrafluoroethylene (PTFE) to become the first company to produce the film, and then laminated the fabric with the fabric named GORE-TEX. But because PTFE has very strong chemical inertia, almost no material can be laminated with other fabrics. The first generation of fabric is very poor fastness. Later, after continuous efforts, it was greatly improved by combining with other hydrophilic film layers to become composite films and special treatment on the films. Generally, Gore-Tex fabric pressure can reach 10000mm, washed 6-7 times pressure was decreased significantly; the moisture quantity can reach 10000g/sqm*24hrs, but this is not just out of the fabric can reach this value, need to go through a few times of washing, the washing part of glue, the available pore increased, moisture permeability increased.
The PTFE fabric is now mainly represented by the Gore and Donaldson in the United States. Gore produced thin film and made compound, not selling thin film alone, designate better garment manufacturers to make clothing, and have a single individual salesman to cooperate with them. Donaldson produces only thin films and makes composite manufacturers in Japan. The two companies are also very competitive on the market. Domestic PTFE manufacturers are also gradually rising, but they are mainly composed of one component PTFE thin film. They are not combined with hydrophilic film, and the water washing fastness is generally only about five times. Last time I met a manufacturer in Indonesia at the industrial fabric exhibition in Shanghai, which was said to be about five times.
Although the waterproof and moisture permeability of the PTFE fabric is better than that of other fabrics, but because of its chemical inertness in this province, the film is difficult.