Undyed fiber is a colored fiber spun directly through dope dyeing technology, which can fundamentally solve the problem of fiber dyeing consumption and wastewater discharge, and save a lot of dyeing costs. At the same time, the fabrics woven from dye-free fibers are bright in color, uniform in color, durable, not easy to fade, and friendly to the human body. Dye-free fiber has therefore become the “new favorite” in the textile fashion industry.
With the strict implementation of the new national environmental protection law, the requirements for post-dyeing of fibers, yarns and fabrics are becoming more and more stringent. The new environmental protection law has increased the requirements for the discharge of colored sewage and organic matter, which has caused a sharp increase in dyeing costs. With the price increase in the printing and dyeing industry, the cost advantage of dye-free fiber has become increasingly prominent.
Significantly reduces dyeing costs and is environmentally friendly
Dope coloring of dye-free fibers means that before the polyester melt (or slices) enters the spinning box, the dye (masterbatch) that has been dried, melted, filtered, and measured is injected into the polyester melt, and then passes through the process together with the polyester melt. After the high-efficiency static mixer is fully and evenly mixed, they enter the spinning box together for spinning. In the melt spinning process, dye-free fiber can omit most of the dyeing and finishing processes, greatly reducing carbon dioxide and COD emissions, significantly saving water and chemicals, and achieving a high degree of integration of rich colors and clean production.
Dye-free fiber mainly has three advantages:
First, dye-free fiber reduces the consumption of raw materials, avoids environmental pollution, reduces dyeing costs, and saves huge pollution control costs.
According to experts, considering the differences between light, medium and dark colors, the cost per ton of undyed fiber is 30% to 50% lower than the cost per ton of post-dyed fiber. For example, medium-color undyed fiber can save 5,000 yuan in dyeing costs per ton, which is equivalent to saving 11,000 kilowatt hours of electricity, 100 tons of water, and 150 kilograms of dyeing materials. The economic and social benefits are very significant.
Second, dye-free fiber has the characteristics of uniform dyeing, which avoids defects such as color difference, color spots, and color flowers that are easy to occur in conventional dyeing.
Third, there are rich varieties of dye-free fibers, and the products have achieved functionalization, differentiation, high color fastness, and high brightness. The development trend will also be effectively combined with functionality, elasticity, ecological affinity, and comfort.
At present, dye-free fiber has expanded from dye-free polyester to nylon, acrylic, polypropylene, aramid, spandex and other fields.
The output of dye-free polyester currently ranks first among dye-free fibers. Undyed polyester filament can be combined with short fiber for composite spinning, and its yarn has both filament and short fiber styles. Dye-free polyester industrial yarn is mainly used in automobile seat belts, military luggage fabrics, slings and other fields.
Dye-free acrylic fiber is a rapidly developing type of dye-free fiber. A petrochemical company in Shanghai has currently launched a “polyacrylonitrile dye-free fiber”. This fiber is made by adding pigments to the interior of the fiber during the production process of polyacrylonitrile fiber and then spinning it. By ���Colored raw materials are added before spinning, so basically no colored sewage is produced during the fiber production process, thus avoiding the generation of a large amount of colored sewage in the downstream dyeing factory, which is green and environmentally friendly.
At the same time, polyacrylonitrile dye-free fiber has high color fastness due to the natural characteristics of the pigments added inside the fiber, such as color fastness to rubbing, color fastness to washing, color fastness to light and color fastness to weathering. The degree is significantly higher than that of post-dyed fibers.
A person in charge of Shanghai Petrochemical said: “After 10 years of continuous development, we have completed small-scale laboratory tests, pilot tests, and industrial production, and have formed our own intellectual property rights. We also work closely with downstream spinning companies to Successfully completed the transition from fiber to yarn for polyacrylonitrile dye-free fiber and successfully entered the market. ”
According to reports, the company achieved industrial production of polyacrylonitrile dye-free fiber in 2008. In 2014, the company’s polyacrylonitrile dye-free fiber sales volume was approximately 1,500 tons, an increase of approximately 50% over 2013. In 2015, polyacrylonitrile dye-free fiber was successfully shortlisted for the “2015/2016 China Fiber Trends”.
The person in charge also introduced that the current applications of the company’s polyacrylonitrile dye-free fiber are mainly divided into clothing and outdoor use. The clothing series uses dye-free acrylic fiber blended with conventional fibers, and is widely used in the preparation of hemp gray yarn, chenille yarn and other series. Products; outdoor series are mainly used to make awnings, car roofs, tents, boat awnings, and outdoor decorative home fabrics. The market demand is huge and the products have high added value.
Dye-free spandex has also been widely used in recent years. Undyed spandex fiber can be blended with polyester, acrylic, cotton, wool and other fibers to give the fabric excellent elasticity. It is generally used to produce black stockings and high-end fabrics that do not require dyeing.
Black spandex dye-free fiber has properties such as high temperature resistance, chlorine resistance, dyeability, and anti-aging. At the same time, the fiber has high color fastness, which is about 2 to 3 times that of ordinary fabrics. Black spandex dye-free fiber products can replace imported products, and their ultra-fine denier specifications can more widely meet customers’ needs for fine fiber products, so they are widely used in various high-end fabrics.
Dye-free nylon can be interwoven with dye-free polyester to develop plain stretch fabrics, which are suitable for spring and summer fashion. Polyester-nylon composite silk twill stretch fabrics can also be developed, which are suitable for autumn and winter clothing.
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