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A synthetic fiber obtained by spinning polyvinyl alcohol as a raw material.
Introduction
A synthetic fiber obtained by spinning polyvinyl alcohol as a raw material. The fiber is treated with formaldehyde to obtain polyvinyl formal fiber, which is called vinylon in China and internationally called vinylon. The fiber obtained by spinning compared with the low molecular weight polyvinyl alcohol as a raw material is water-soluble, and is called a water-soluble polyvinyl alcohol fiber. The general polyvinyl alcohol fiber does not have the necessary hot water resistance, and the practical application value is not large. Polyvinyl formal fiber has the characteristics of softness and warmth, especially the moisture absorption rate (up to 5%) is relatively high among synthetic fiber varieties, so it is called synthetic cotton; but its heat resistance is poor, and the softening point is only 120 ° C.
History
In the early 1930s, Wacker Chemie of Germany first produced polyvinyl alcohol fibers. In 1939, Japan's Sakurada Ichiro, Yazawa Tony, and North Korea's Li Shengji treated the fiber with formaldehyde to produce a heat-resistant polyvinyl formal fiber. In 1950, it was made by Japan Kurashiki Rayon Co., Ltd. (now Kuraray). The company has built an industrial production facility. In 1984, the world production of polyvinyl alcohol fiber was 94 kt. In the early 1960s, water-soluble polyvinyl alcohol fibers produced by Japan's Vinylon and Kuraray were put on the market.
production method
The raw material polyvinyl alcohol used for the polyvinyl alcohol fiber has an average molecular weight of 60,000 to 150,000, a thermal decomposition temperature of 200 to 220 ° C, and a melting point of 225 to 230 ° C. Polyvinyl alcohol fibers can be obtained by wet spinning and dry spinning. The polyvinyl alcohol fiber is subjected to acetalization treatment of the heat-treated polyvinyl alcohol fiber to obtain a polyvinyl formal fiber. The acetalization process is carried out by removing the tow (sodium sulphate) by water washing, and then passing through the hydroformylation solution (composed of the hydroformylating agent formaldehyde, the diluent water, the catalyst sulfuric acid, the swelling agent sodium sulfate), and then washing with water. the process of. The tow can also be cut into short fibers, sent to a post-treatment machine by air flow, and acetalized on a stainless steel mesh. In order to improve the fiber properties, a polyvinyl alcohol solution (concentration: 16%) containing a crosslinking agent boric acid can be wet-spun, and the obtained nascent fiber is solidified in an alkaline coagulation bath, neutralized, washed with water, and stretched in multiple stages. And heat treatment, a filament having a strength of 106 to 115 cN/dtex can be obtained. This product is called a boron-containing wet filament.
use
Polyvinyl formal fibers can be used in the industrial field for the production of canvas, tarpaulins, filter cloths, conveyor belts, packaging materials, overalls, fishing nets and offshore work cables. High-strength, high-modulus filaments can be used as the lining material for conveyor belts, lining materials for various hoses, tapes and rubber shoes, and can also be used to make bicycle tire cords. Because this fiber can resist the alkalinity of cement and has good adhesion and affinity with cement, it can replace asbestos as a reinforcing material for cement products. It can be blended with cotton to make a variety of clothing and interior products, as well as knitwear. However, the heat resistance is poor, the obtained fabric is not stiff, and it cannot be washed in hot water. In addition, it is also useful in terms of non-woven fabrics, paper making, and the like.
Dissolve
The polyvinyl alcohol fiber can be blended with other fibers, and then dissolved after the textile processing to obtain a high-grade textile of the spun yarn, and a non-twisted yarn or a weftless carpet can also be obtained. It can also be used as a binder in papermaking to increase the strength and toughness of paper. In addition, it can also be used for special purpose work clothes, surgical sutures, etc.
Modified polyvinyl alcohol fiber
An important modified variety is vinyl chloride-polyvinyl alcohol graft copolymer fiber, which is called polyvinyl chloride in China. It uses a low polymerization degree polyvinyl alcohol aqueous solution as a dispersion medium to graft copolymerize vinyl chloride and polyvinyl alcohol under the action of a catalyst; from the obtained copolymer emulsion, it is spun by an emulsion spinning method (see chemical fiber spinning). Fiber; finished with a similar post-treatment process with polyvinyl acetal fibers to produce a finished fiber. It combines the advantages of polyvinyl chloride fibers and polyvinyl formal fibers.
Chiffon Fabric,Printed Chiffon Fabric,Cotton Chiffon Fabric,Plain Chiffon Fabric
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