Guide: Acetate fiber was born in the early 20th century, and was successfully trial-produced by the United Kingdom in the early 1920s and realized industrial production. It is currently the second largest variety of cellulose fiber after viscose fiber. Acetate fiber can be used to make textiles, cigarette filters, film bases, and plastic products.
Popular Fiber: Acetate Fiber
Acetate fiber, English name cellulose acetate, abbreviated as CA. Acetate fiber is divided into diacetate fiber and triacetate fiber, which is a kind of man-made fiber. Using cellulose as a raw material, it is converted into a chemical fiber made of cellulose acetate through a chemical process. It was first prepared in 1865 as an acetate of cellulose. Cellulose is esterified with acetic acid or acetic anhydride under the action of a catalyst to obtain a thermoplastic resin. The hydroxyl group in the cellulose molecule is esterified with acetic acid to obtain a chemically modified natural polymer. Its performance depends on the degree of acetylation.
According to the degree of substitution of acetyl groups by hydroxyl groups in cellulose, it can be divided into diacetate and triacetate.
The diacetate is formed by partial hydrolysis of the first ester, and its degree of esterification is lower than that of the triacetate. Therefore, the heating performance is not as good as that of the tri-vinegar, the dyeing performance is better than that of the tri-vinegar, and the moisture absorption rate is higher than that of the tri-vinegar.
Triacetin is a type one ester, without hydrolysis, its esterification degree is relatively high. Therefore, it has strong light and heat resistance, poor dyeing performance, and low moisture absorption rate (also called moisture regain).
In the molecular structure of cellulose acetate, the hydroxyl group on the cellulose glucose ring is replaced by an acetyl group to form an ester bond. The degree of esterification of cellulose diacetate is lower than that of cellulose triacetate due to hydrolysis. In the supramolecular structure of cellulose diacetate, the amorphous region is larger, while cellulose triacetate has a certain crystalline structure, and the symmetry, regularity and crystallinity of the fiber macromolecules are all higher than that of cellulose diacetate.
The surface of the longitudinal fibers is smooth and uniform, with obvious grooves. It can be seen from the cross-sectional morphology that the fibers have no skin core structure and are clover leaf-shaped, with relatively smooth periphery and few shallow serrations.
The weak alkaline agent basically did not cause damage to the acetate fiber, and the fiber weight loss rate was very small. After encountering strong alkalis, especially cellulose diacetate, it is prone to deacetylation, causing weight loss, and the strength and modulus also decrease. Therefore, the pH value of the solution for treating cellulose acetate should not exceed 7.0. Under standard washing conditions, it has strong resistance to chlorine bleaching, and can also be used for dry cleaning with perchloroethylene.
Cellulose acetate is completely dissolved in acetone, DMF, and glacial acetic acid, but insoluble in ethanol and perchloroethylene. According to these characteristics, acetone can be used as the spinning solvent of acetate fiber, and tetrachloroethylene can be used to dry-clean the acetate fabric.
Acetate fiber has good acid resistance and stability. The common sulfuric acid, hydrochloric acid, and nitric acid will not affect the strength, gloss and elongation of the fiber within a certain concentration range; but it can be dissolved in concentrated sulfuric acid, concentrated hydrochloric acid, and concentrated nitric acid.
Although cellulose acetate is derived from cellulose, during the esterification process, a large part of the polar hydroxyl groups on the glucose ring of cellulose are replaced by acetyl groups into esters. Therefore, the dyes commonly used in dyeing cellulose fibers have almost no affinity for cellulose acetate. , It is difficult to get dyed. The most suitable dyes for acetate fibers are disperse dyes with low molecular weight and similar dyeing rate.
Acetate fiber or fabric dyed with disperse dyes is bright and bright, has good levelling effect, high dye exhaustion rate, high color fastness, and complete chromatogram.
5.1 Acetate fiber not only has a certain degree of water absorption, but also has the ability to quickly take off after absorbing water.
5.2 The thermal stability of acetate fiber is good. The glass transition temperature of the fiber is about 185 ℃, and the melting termination temperature is about 310 ℃. At the end of heating, the weight loss rate of the fiber is 90.78%; the breaking strength of the acetate fiber is 1.29 cN/ dtex, and the strain is 31.44%.
5.3 The density of acetate fiber is smaller than that of viscose fiber, which is closer to that of polyester; its strength is the lowest among the three fibers.
5.4 Acetate fiber has relatively good elasticity, similar to silk and wool.
5.5 The boiling water shrinkage rate is low, but high temperature treatment will affect the strength and gloss of the fiber, so the temperature should not exceed 85 ℃.
The trees that have grown for many years are made into wood pulp, the wood pulp impurities are removed and filtered, and the cellulose ester is treated with acetic anhydride to form cellulose ester. The cellulose acetate is dissolved, defoamed, spinned, coagulated, drawn, and wound. Acetate filaments of cellulose fibers are formed.
Di vinegar is formed by partial hydrolysis of first vinegar, and its esterification degree is lower than that of tri vinegar. Therefore, the heating performance is not as good as trivinegar, and the dyeing performance is better than trivinegar (diacetic acid is generally dyed at 85~100℃, and triacetic acid is generally dyed at 130℃), and the moisture absorption rate is higher than that of trivinegar (when the relative temperature is 65%, the moisture regain rate of diacetic acid is 6.5 %, while triacetic acid is only 3.5%).
The vinegar fiber resembles real silk, with a soft hand feeling, bright color after dyeing, beautiful and beautiful, and resistant to sunlight, but its strength and abrasion resistance are poor. It is mainly used to make clothes (such as underwear and knitwear) accounting for 84%; home decorations ( Such as furniture cover) accounted for 15%; industrial use (such as car seat cushion) about 1%.
Fibers spun from cellulose triacetate have many characteristics similar to real synthetic fibers (such as polypropylene fibers, nylon and polyester fibers). Chemical fiber is hydrophobic, heat treatment can improve crystallinity, the fabric is easy to finish, wrinkle-resistant, dimensionally stable, and easy to dry. Its most important feature is its stable shape. The textile performance of acetate fiber is similar to that of synthetic fiber.
There are only more than 20 manufacturers of acetate fiber in the world, mainly Eastman, Celanese, S. Amereic in the United States; Novaceta in Italy, Mitsubishi Acetate in Japan, Teijin, and Cowz in the United Kingdom, etc. It accounts for 90% of the world's total output.
China's cellulose acetate industry started in the late 1950s. In recent years, due to the demand of various industries in China, the development of the cellulose acetate industry has entered a stage of accelerated growth, but the overall development scale is still small. At the same time, Chinese cellulose acetate companies have insufficient development of downstream products, and the product structure is very unreasonable. The production varieties are also limited to acetic acid tow for cigarettes. Acetate fiber for textiles is all dependent on imports, with an annual import of about 2,000 tons, while China’s annual acetic acid The fiber demand is about 10,000 tons or more.