What is waterproof and breathable fabric (fabric)? What is waterproof and breathable functional fabric?

What is waterproof and breathable fabric (fabric)? What is waterproof and breathable functional fabric?

The indicator for measuring waterproofing is the height of water pressure per square millimeter, expressed in mm of water column. The air permeability is measured by the weight of water vapor per square millimeter that can pass through in 24 hours.

Waterproof and breathable functional fabric (fabric) Introduction

When you go hiking, it may rain suddenly, 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 problem 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 fabric refers to water under a certain pressure Without being immersed in the fabric, 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 to maintain the comfort of the garment. It is a high-tech, unique Featured functional fabrics. Waterproofing is not a problem for ordinary fabric workers. The key is how to achieve moisture permeability. Next, let’s take a deeper look at the types of waterproof and breathable fabrics.

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. Clothing matching

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-absorbent 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. Moisture permeability is achieved through coating

Using dry methoddirect coating,Transfer coating, Foam coating, phase inversion or Wet coating (Solid coating) and other process technologies combine various A coating agent with waterproof and moisture-permeable functions is applied to the surface of the fabric, so that the pores on the surface of the fabric are closed or reduced to a certain extent by the coating agent, thereby achieving 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 fabric now developed has given the coated fabric a new lease of life. It not only has high physical properties such as waterproof and moisture permeability, but also the surface fabric can Made of 100% Teflon, the washing fastness can reach more than 25 times, and 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 we can create a pore with a diameter between water vapor and rainwater film, then can it be achieved that is both waterproof and breathable? The American company GORE became the first company to produce this film using polytetrafluoroethylene (PTFE). It was laminated with fabric and then named GORE-TEX. . However, due to the very strong chemical inertness of PTFE, there are almost no materials that can be laminated well with other fabrics, and the fabric fastness is very poor. Later, after continuous efforts, by combining it with other hydrophilic film layers, Together they become a composite film, and special treatment is carried out on the film to greatly improve the fastness. It is generally believed that the water pressure of Gore-Tex fabric can reach 10000mm, the water pressure will drop significantly after 6-7 times of washing; the moisture permeability can reach 10000g/sqm*24hrs, but this value is not achieved by just making the fabric, it needs to be washed several times Wash with water to remove part of the glue, increasing the available pores and increasing 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 now gradually emerging, but they mainly use single-component PTFE films without compounding with hydrophilic films. 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 has a high burning temperature405℃, large-scale Application makes GORE-TEX gradually become an environmental killer. Faced with such a problem, GORE established a waste clothing recycling mechanism called Balance Project 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.

Disclaimer:

Disclaimer: Some of the texts, pictures, audios, and videos of some articles published on this site are from the Internet and do not represent the views of this site. The copyrights belong to the original authors. If you find that the information reproduced on this website infringes upon your rights, please contact us and we will change or delete it as soon as possible.

AA