A magical fiber PVA fiber

Water-soluble fibers, water-soluble polyvinyl alcohol (PVA), are a valuable functionally differentiated fiber. In the 1930s, the polyvinyl alcohol (PVA) fiber originally developed was made into a medical surgical yarn and surgical suture in Germany.

In the Second World War, countries such as the United States used PVA fibers to make parachutes for laying mines. In the 1950s, Japan began further research on the water-soluble use value of PVA fiber. By the end of the 1950s, Japan's water-soluble fiber production accounted for 20% of the total production of vinylon. In the past 20 years, there has been a new breakthrough. Sexual development has developed new water-soluble fibers with better performance.

China has started the research and development of water-soluble fiber from the late 1970s. In recent years, it has made gratifying progress, reversed the situation of relying on imports, single product varieties and low grades, and has formed scale production and achieved certain economic benefits.

 

1. Characteristics and development of water-soluble fibers

Water-soluble PVA fiber not only has ideal water-soluble temperature, strength and elongation, but also has good acid, alkali and dry heat resistance, and is odorless and non-toxic after being dissolved in water. The aqueous solution is colorless and transparent, in a short time. The internal energy is naturally decomposed and does not cause any pollution to the environment. It is a 100% green product. In addition, according to recent research results, PVA is the only biodegradable material in large-scale synthetic polymers. It is the development of the water-soluble PVA fiber with different properties that utilizes the unique properties of water-soluble PVA fiber, and the development of its application range is still being carried out continuously.

Depending on the hydrophilicity of the PVA fibers themselves, specially processed PVA fibers have water solubility not found in other fibers. Water-soluble PVA fibers are available in two major categories: filaments and staple fibers. The current methods for producing water-soluble fibers at home and abroad are as follows:

 1. Wet spinning

The PVA aqueous solution is sprayed into a high-concentration Na2SO4 solution for solidification, and the solidified fiber is drawn and dried under moist heat conditions, and then subjected to dry heat drawing and heat treatment. The advantage of this method is high yield and low cost. The use of modified PVA is also beneficial to the modification of ordinary PVA in the stock solution. The disadvantage is that the process is difficult, and Na2SO4 enters the fiber surface. It is difficult to produce PVA fiber which is free from Na2SO4 salt and soluble in water below 80 °C, and the surface of the fiber and the internal structure are irregularly deformed due to the direct removal of the solvent in the coagulation solution. The improvement in strength is limited.

The PVA aqueous solution is sprayed into a high-concentration Na2SO4 solution for solidification, and the solidified fiber is drawn and dried under moist heat conditions, and then subjected to dry heat drawing and heat treatment. The advantage of this method is high yield and low cost. The use of modified PVA is also beneficial to the modification of ordinary PVA in the stock solution. The disadvantage is that the process is difficult, and Na2SO4 enters the fiber surface. It is difficult to produce PVA fiber which is free from Na2SO4 salt and soluble in water below 80 °C, and the surface of the fiber and the internal structure are irregularly deformed due to the direct removal of the solvent in the coagulation solution. The improvement in strength is limited.

In China, the wet spinning process is used to produce water-soluble fibers. Due to the difficulty of this process, only water-soluble fibers with a water-soluble temperature of 70 ° C to 90 ° C are produced. Other physical properties need to be further improved. The Shanghai Petrochemical Weilun Plant has developed a water-soluble PVA with a water-soluble temperature of 70±5°C; the Sichuan Weilun Plant also produces a water-soluble PVA with a water-soluble temperature of 80±5°C.

 2. Dry spinning

The high-concentration PVA fiber solution is sprayed into hot air to evaporate the solvent and solidify into a wire, which is then obtained by dry heat drawing and heat treatment. The advantage of this method is that the spinning process is simple, and it is suitable for producing a variety of water-soluble filaments, and is particularly suitable for producing water-soluble fibers at normal temperature. However, this method has the disadvantages of low fiber fineness, low yield, and high cost.

 3. Melt, semi-melt spinning

Adding a certain amount of water to plasticize the PVA, and then making it semi-molten at a very low temperature (120 ° C ~ 150 ° C), pressing out from the spinneret at a large pressure, and then cooling in the air. solidification. This method can be used to spun monofilament or multifilament, but has not seen a large scale of application in industrial production.

 4. Borate gel spinning

A PVA gel solution to which boric acid has been added is extruded into a solution of NaOH and Na2SO4 to form and crosslink. The crosslinked fibers are obtained by drawing, neutralizing, washing, drying, dry heat drawing, and heat treatment under moist heat conditions. The cross-linking of such fibers allows the water-soluble PVA fibers to have good stability in a moderately humid atmosphere, and will be hydrolyzed and dissociated quickly in water, so that their water solubility is not affected.

 5. Frozen glue spinning

The newly developed frozen gel method developed by Kuraray Co., Ltd. is to dissolve PVA as a spinning dope in an organic solvent with a relatively good solubility. It is squeezed into the coagulating solution of the organic solvent from the orifice to rapidly cool into a gel, so that the original solution The trickle forms a stable structure before the solvent is removed, and the solidified fiber has a uniform circular cross-sectional structure. This method gives PVA fibers with low alcoholysis, high strength, low shrinkage, and low adhesion. The method is characterized in that it is anhydrous in the whole process, the solvent and the coagulant used are all organic solvents, and the solvent has a wide polymer dissolving ability, so the same production process can produce different kinds of high polymer fibers. The entire process is completed in a closed system where the solution is completely recycled and recycled, no waste is discharged, and the environment is not polluted. Kuraray has successfully produced a new water-soluble PVA fiber K-II using this method, which has a water-soluble temperature of 0-100 ° C, and also has biodegradability, alkali resistance, pressure resistance and heat resistance, and high strength. Low shrinkage, high flame retardancy and easy fibrillation.

Second, the application of water-soluble fiber in the textile industry

The water-soluble fiber is blended with other fibers as an intermediate fiber, and the water-soluble fiber is dissolved after the textile processing to obtain a high-grade high-grade textile. In April 1997, the International Wool Secretariat (IWS) and the Japanese Kuraray Co., Ltd. jointly developed the wool/polyvinyl alcohol wool manufacturing technology to the world wool industry by utilizing the excellent performance of the new water-soluble PVA fiber K-II at room temperature. And has entered the market. It is made of a blend of wool with a low count and a water-soluble PVA fiber. After spinning and weaving into a fabric, the PVA fiber is removed in the finishing process to obtain a high-strength, light-weight high-grade pure wool fabric. Created a new era of low-cost high-quality pure wool fabrics. China has also used domestic water-soluble PVA fiber to produce a batch of high-grade hemp fabrics and high-strength light and pure wool fabrics.

The water-soluble fiber is used for sizing of fabric warp yarn, and has the advantages of uniform sizing, stable chemical structure, good corrosion resistance, simple and easy process. After weaving with water-soluble fibers as weft yarns, the weft yarns are dissolved in hot water to form a matte felt. This method is also suitable for weaving of warp knit fabrics, which is advantageous for garment knitting. In addition, water-soluble fibers are also used in the production of crepe-free yarns, knitwear tailoring, and defense as a special overalls.

The water-soluble non-woven fabric is mainly used as the embroidered skeleton material in the garment industry. It can be embroidered on it alone, or it can be used together with the fabric of the garment. After processing, the non-woven fabric can be disposed of in hot water. Flower pattern. The development and application of water-soluble fibers are particularly important in the wool textile industry. Now, Kuraray Japan has sent information on wool/PVA wool manufacturing technology to wool manufacturers around the world. In Japan, 30 wool companies have been established, and overseas, more than 100 companies in more than 20 countries have established contacts. Four to five large Italian companies have started selling.

 

It is reported that the International Wool Bureau has held technical lectures in Beijing, Shanghai and other places to introduce the "wool / PVA" manufacturing technology, which has attracted the attention of the domestic wool textile industry. At present, the enterprises have shown great interest in the production and application of low-temperature water-soluble PVA fibers.

In addition, Kuraray is researching a new composite material of "Kele K-II" water-soluble fiber and natural fibers such as cotton and hemp, as well as high-performance fibers such as polyamide fiber, fluorine fiber and carbon fiber. Although these high-performance fibers have some special excellent properties, due to the crimping, strength, oil, etc. of these fibers, there are some difficulties in various processes such as spinning and weaving, and K-II" water-soluble fiber composites will be improved. At the same time, the composite hollow cotton yarn of "Kellon K-II" water-soluble fiber and cotton fiber jointly developed by Kuraray and Cola Spinning Co., Ltd. has achieved success, and has been sold under the trade name "SPINAIR".

China's research on water-soluble fiber began in 1979. Although it started late, it has received more and more attention from all aspects, especially in recent years, especially in the textile, linen, embroidery and other industries. We should continue to strengthen the research on the production of water-soluble fibers. The water-soluble fibers need to be strengthened, improved and further expanded in terms of variety, quality and application. Water-soluble fiber has great market potential. To this end, it is necessary to develop water-soluble fibers that meet market needs and performance by transforming and updating equipment and continuously adjusting and optimizing processes, and gradually catch up with the development of foreign water-soluble fibers.

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