Vinylon is the commercial name of polyvinyl formal fiber, also known as vinylon, or transliteration of vinylon. Its performance is close to cotton, so it is also called artificial cotton.
Polyvinyl formal fiber is the product of formaldehyde acetalization of polyvinyl alcohol polymer.
Ordinary polymers are polymerized from monomers. However, polyvinyl alcohol is not polymerized from vinyl alcohol. Because vinyl alcohol is very unstable and will rearrange itself into acetaldehyde, vinyl alcohol is actually a non-existent substance.
1924, German chemists W.O.Hermann and W.Heiler made polyvinyl alcohol, which was prepared by dissolving polyvinyl acetate in methanol and adding sodium hydroxide for alcoholysis;
Polyvinyl acetate is polymerized from vinyl acetate. Vinyl acetate can be used to prepare acetic acid from acetylene. As early as 188 1 years ago, Russian chemist Kuchelov made acetaldehyde from acetylene and oxidized it to acetic acid. Then acetylene and acetic acid reacted with zinc acetate as catalyst to produce vinyl acetate.
So polyvinyl alcohol is actually made of acetylene. As early as 193 1, the Germans had mastered the technology of producing fibers and films by using polyvinyl alcohol and sold them under the trade name of Synthofil. However, it was later found that this kind of fiber is very hydrophilic, and the clothes sewn with this fiber can't be washed with water when they are dirty, otherwise the original clothes can't be found; If you put clothes in hot water, they won't be found because they dissolve in water. This is mainly because there are many hydroxyl groups (-OH) with strong affinity for water on the long-chain molecules of polyvinyl alcohol:
By 1939, Sakurada Ichiro (1904- 1986) and Lee Seung Gi (1905-? ) and Dr. Hideki Yano of Zhongyuan Textile Research Institute in Japan proposed heat treatment and acetalization treatment methods to make it a new fiber Yamada with good heat resistance and water solubility. History of world inventions and discoveries. Wang Guowen, etc. Translate it. Beijing: Patent Literature Publishing House, 1989. . The so-called heat treatment is to heat the fiber at 220~270℃ for 5~ 10 minutes to reduce the shrinkage of the fiber and improve the hot water resistance of the fiber. Acetalization is the condensation of aldehyde group (-—CHO) in formaldehyde, benzaldehyde and other aldehyde molecules with hydroxyl group (-OH) in polyvinyl alcohol molecules to generate water, thus removing hydrophilic -OH in polyethylene molecules. Formaldehyde is generally used, and the product is polyvinyl formal fiber, usually called polyvinyl acetal fiber, and the word "A" is omitted.
Acetalization treatment cannot remove all hydroxyl groups. When the acetalization degree is high, the performance of the fiber is not ideal, so the acetalization degree is generally controlled at only 30%~35%, that is, a considerable amount of hydrophilic hydroxyl (-OH) remains in the long chain of fiber macromolecules. Therefore, vinylon has higher hygroscopicity than other synthetic fibers.
194 1- 1942, Japan Zhongyuan Textile Research Institute and Cangfu Rayon Company built pilot production facilities with an annual output of 150 tons and 60 tons respectively, which were shelved after World War II and were not industrialized until after the war.
Because the hygroscopicity of vinylon is similar to that of cotton, it is often used as a substitute for cotton, and blended with cotton into cotton muslin, poplin, khaki and corduroy. Vinylon products are durable and cheap, and are used as canvas and filter cloth in industry.
With the preparation of vinylon, polyester and acrylic fiber are produced one after another. Polyester is the trademark name of polyester fiber.
Before making polyamide fiber, Karozes used sebacic acid and ethylene glycol for polycondensation to obtain polyester. It was found that it had the performance of spinning fiber, but it was easy to hydrolyze and dissolve in organic solvent, so he gave up and developed polyamide instead.
J. R.Whinfield, a British chemist who participated in the development of synthetic fibers of Carothers Company, realized that to become a polymer of industrial textile fibers, it must have a high melting point, be able to resist the influence of chemicals and solvents, and have a high molecular linear structure. After returning to England, he and chemist J.T.Dickson chose ethylene glycol (CH2OHCH2OH) and terephthalic acid (HOOCC6H4COOH) for polycondensation, which was successful in 1939. Terephthalic acid has a more linear symmetrical structure than phthalic acid or isophthalic acid, and the existence of benzene nucleus in polymer molecules can improve the melting point of products.
Due to the outbreak of World War II, the British supply department thought that this new polymer might become a military material, so it asked the chemical laboratories of scientific and industrial research departments to continue their research to produce the number of laboratories. 1943 samples were sent to Imperial Chemical Industry Company and developed into textile materials, which were produced in Wilton, Yarks under the trade name of polyester. Dupont Company of the United States purchased a patent to build a factory in Kingston, North Carolina, and put it into production in March 1953, with the trade name of Polyester. We transliterated it and translated it into "polyester".
In industrial production, dimethyl terephthalate and ethylene glycol are used for transesterification. The so-called transesterification reaction, that is, the exchange of methyl groups (-—CH3) between ethylene glycol and dimethyl terephthalate, is carried out under the condition of using catalysts such as zinc acetate.
Polyethylene terephthalate is a colorless and transparent polyester monomer. After polymerization, polyethylene terephthalate is produced in the form of solid particles or melt for direct spinning.
Terephthalic acid and ethylene glycol were polymerized after direct esterification, which was not used in industrial production for a long time. This is because terephthalic acid has a high melting point and low solubility in water, so it is difficult to purify. At the same time, the reaction speed of terephthalic acid and ethylene glycol is slow, and the solid-liquid reaction is not easy to control.
The thermal stability of polyester is better than nylon. As a clothing fiber, polyester is characterized by good wrinkle resistance and shape retention. The clothes made of polyester are crisp and wrinkle-free, with beautiful appearance and good strength, and the impact strength is four times higher than that of nylon. But the disadvantage is that the hygroscopicity is small, and the clothes woven with it feel sultry, easy to take static electricity and easy to be polluted.
After polyester, acrylic fiber appeared. Acrylic fiber is the trade name of polyacrylonitrile fiber in China. The performance of acrylic fiber is very similar to wool, so it is called "synthetic wool" and "artificial wool".
In the early 1940s, DuPont successfully researched acrylic fiber. The experimental samples were sent to the U.S. government for military use in 1942, and were trial-produced in 1945. orlon was published as a trade name in 1948, and industrial production began in 1950. Acrylic fiber is a polymer of acrylonitrile.
Acrylonitrile is a colorless flammable liquid, which is toxic. It can be made of petrochemical products acetylene or ethylene.
This kind of fiber has excellent light fastness. It was originally used to make awnings, car hoods and so on. Later, it was found that its properties were very similar to wool, and it was blended with wool.
The acrylic fiber seen in the market is not a polymer polymerized from acrylonitrile, but is usually polymerized from three monomers: vinyl chloride (CH2=CCl), vinyl chloride (CH2=C=Cl2) and vinyl cyanide (CH2=C=(CN)2). Adding chlorine to the composition can prevent fire.