Acetate fiber was born at the beginning of the 20th century and was successfully trial-produced in the UK in the early 1920s and achieved industrial production. At present, it is the second largest variety of cellulose fibers after viscose fiber. Acetate fiber can be used in the manufacture of textiles, cigarette filters, sheet bases, plastics, and the like.
What Is Acetate Fiber?
Acetate fiber, English name cellulose acetate, CA for short. Acetate fiber is divided into diacetate fiber and triacetate fiber, which is a kind of man-made fiber. It is a chemical fiber made of cellulose as raw material and converted into cellulose acetate by chemical synthesis. First prepared in 1865, it is an acetate ester of cellulose. A thermoplastic resin obtained by esterification of cellulose with acetic acid or acetic anhydride under the action of a catalyst, a chemically modified natural high polymer obtained after the hydroxyl group in the cellulose molecule is esterified with acetic acid. Its properties depend on the degree of acetylation.
Classification Of Acetate Fibers
According to the degree of substitution of hydroxyl groups in cellulose by acetyl groups, it can be divided into diacetate and triacetate.
Di-ester is formed by partial hydrolysis of one-type acetate, and its esterification degree is lower than that of tri-ester. Therefore, the heat performance is not as good as that of tri-vinegar, the dyeing performance is better than that of tri-vinegar, and the moisture absorption rate is higher than that of tri-vinegar.
Triacetate is a type 1 acetate, which has a high degree of esterification without hydrolysis. Therefore, it has strong light and heat resistance, poor dyeing performance, and low moisture absorption (also called moisture regain).
In the molecular structure of cellulose acetate, the hydroxyl groups on the glucose ring of cellulose are replaced by acetyl groups to form ester bonds, and the degree of esterification of cellulose diacetate is lower than that of cellulose triacetate due to hydrolysis. In the supramolecular structure of diacetate fiber, the amorphous region is larger, while triacetate fiber has a certain crystalline structure, and the symmetry, regularity and crystallinity of fiber macromolecules are higher than those of diacetate fiber.
The Structure of Cellulose Acetate
The surface morphology of longitudinal fibers is smooth, relatively uniform, and has obvious grooves; it can be seen from the cross-sectional shape that the fibers have no skin-core structure, and are in the shape of cloverleaf, with smooth periphery and few shallow serrations.
Chemical Properties of Acetate Fiber
- Alkali resistance
The weak basic alkali agent basically did not cause damage to the acetate fiber, and the fiber weight loss rate was very small. In the presence of strong bases, especially diacetate fibers, deacetylation is prone to occur, resulting in weight loss and a decrease in strength and modulus. Therefore, the pH value of the solution for treating cellulose acetate should not exceed 7.0. It is highly resistant to chlorine bleach under standard washing conditions and can also be dry cleaned with perchloroethylene.
- Resistance to organic solvents
Cellulose acetate is completely soluble in acetone, DMF, and glacial acetic acid, but insoluble in ethanol and tetrachloroethylene. According to these characteristics, acetone can be used as a spinning solvent for acetate fibers, and tetrachloroethylene can be used to dry-clean acetate fibers.
- Acid resistance
Acetate fiber has good acid resistance stability. Common sulfuric acid, hydrochloric acid and nitric acid will not affect the strength, luster and elongation of fiber within a certain concentration range; but it can be dissolved in concentrated sulfuric acid, concentrated hydrochloric acid and concentrated nitric acid.
- Dyeing
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 to form esters. Therefore, the dyes commonly used for cellulose fiber dyeing have almost no affinity for acetate fibers. , difficult to dye. The most suitable dyes for acetate fibers are disperse dyes with low molecular weight and similar dye uptake rates.
The acetate fibers or fabrics dyed with disperse dyes have bright and bright colors, good leveling effect, high dye exhaustion rate, high color fastness, and complete chromatogram.
Physical Properties of Acetate Fiber
- Acetate fiber not only has a certain degree of water absorption, but also has the performance of rapid removal after water absorption.
- 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 the heating, the weight loss rate of the fiber is 90.78%; the breaking strength of the acetate fiber is 1.29 cN /dtex, while the strain is 31.44%.
- The density of acetate fiber is smaller than that of viscose fiber, and it is closer to that of polyester; the strength is the lowest among the three fibers.
- The elasticity of acetate fiber is relatively good, similar to silk and wool.
- The shrinkage rate in boiling water is low, but high temperature treatment will affect the strength and gloss of the fiber, so the temperature should not exceed 85 ℃.
Application Of Acetate Fiber
The physical, mechanical and chemical properties of acetate fiber are relatively good, and it has a wide range of downstream applications. Among them, it is most widely used in textiles, biomedical materials, cigarettes and other industries. Because acetate fiber fabrics usually have silk-like luster and feel, they can cater to consumers. The requirements for the combination of beauty and comfort of clothing have always occupied an important position in the field of high-end clothing fabrics, linings and apparel. In addition, acetate fiber is also widely used in electrospinning nanofiber products, plastic products, melt spinning, coatings and other fields.
Application in the cigarette industry
Acetate filters are the most widely accepted mechanical filters among consumers of today’s low-tar and high-tar cigarettes. Widely non-toxic, odorless, impact-resistant, and oil-resistant, without static electricity, small absorption of sunlight, strong adsorption, good elasticity and thermal stability, can selectively adsorb harmful components in flue gas, while retaining certain nicotine without losing the taste of tobacco.
Application in the textile industry
Acetate filament ester is like silk, elegant in luster, smooth in hand, light in texture, low in moisture regain, good in elasticity, not wrinkled, has good drapability and dimensional stability, and has strong dyeing fastness, bright dyeing, and the fabric has Silk-like luster and feel have always occupied an important position in the field of high-end apparel fabrics, linings and apparel.
Application in the biomedicine field
Cellulose acetate membrane electrophoresis is a kind of electrophoresis technology that uses cellulose acetate membrane as a support after the 1950s. High spirituality
Etc. In addition, the non-woven fabric made of acid staple fiber can be used for medical handbooks and wounds without adhesion, and is a high-grade medical and health material.