Waterproof and breathable functional fabric
Waterproof and breathable functional fabric
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 At present, this type of fabric has long been replaced by other waterproof and breathable fabrics.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 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.
2. TPU film
TPU is the abbreviation of thermoplastic polyurethane film, which is a non-porous hydrophilic film. Since the film itself has no pores, the waterproof effect is naturally very good, and it also makes the fabric windproof and warm. Moisture permeability is mainly achieved through its hydrophilic properties. It relies on the difference in vapor pressure inside and outside the clothes to transfer steam from places with high pressure to places with low pressure, thereby achieving the function of moisture permeability. I have also been engaged in the production of TPU composite fabrics for a long time, so I will give a brief introduction.
Product Characteristics:
A. Green and environmentally friendly
B. Excellent breathability and moisture permeability
C. Absolutely waterproof, anti-blood stain, and antibacterial
D. Windproof and cold-resistant, velvet-proof and smooth
E. Durability, super water-repellent finish
F. Easy to decontaminate and clean, can be washed normally
Scope of application:
A.Field military uniforms, firefighting,Military special clothing
B. Protective equipment, military tents, sleeping bags and postal bags
C. Clothing for mountaineering, skiing, golf and other sports
D. Materials for shoes and hats, bags, blackout curtains, anti-UV umbrella cloth
E. Rainproof and breathable ponchos and casual windbreakers
F. Medical supplies
Product specifications:
1. Door width: 1500mm
2. Product thickness: 0.012~0.025mm
3. Low-permeability transparent mask, low-permeability fog mask, low-permeability milky white mask
Moisture permeability index: greater than 1000g/m2*24hrs (ASTME96BW2000 version)
Hydrostatic pressure resistance index: greater than 10000mmH2O (AATCC127)
4. Medium-transparent transparent mask, medium-transparent mist mask, medium-transparent milky white mask
Moisture permeability index: greater than 3000g/m2*24hrs (ASTME96BW2000 version)
Hydrostatic pressure resistance index: greater than 10000mmH2O (AATCC127)
5. Highly transparent transparent film, high-permeable mist mask, high-permeable milky white mask
Moisture permeability index: greater than 5000g/m2*24hrs (ASTME96BW2000 version)
Hydrostatic pressure resistance index: greater than 10000mmH2O (AATCC127)
6. Suitable for laminating various fabrics such as knitted, woven, and non-woven fabrics
The most popular TPU composite fabrics on the market now are:
1. Four-sided elastic + TPU + polar fleece, which is what people often call SoftShell. The four-sided elastic is mainly 75D (for women’s clothing) and 100D (for men’s clothing), and the polar fleece is mainly 75D/72F and 100D/144F. It can have many styles such as plain weave, twill weave, plaid, etc. The fabric can also be made into garments together with knitted composite jerseys such as 30D/24F, 50D, 75D, etc. Because it is waterproof, breathable, windproof and warm, its use is no longer limited to ordinary outdoor sportswear. Many large foreign companies use it as work clothes for their employees. One of my Japanese clients actually used it as work clothes for waiters at a ramen restaurant!
2. Chemical fiber woven fabric + TPU + Tricot (warp knitted mesh fabric). Woven fabrics mainly include pongee, taslan, oxford, peach skin, nylon, etc. Ordinary ones such as 228T Taslan can be used as the main fabric of jackets; nylon camouflage printed fabrics can be used as military clothing; fluorescent fabrics can be used as police uniforms and other work clothes; etc.
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