Cellulose acetate, the English name is cellulose acetate, or CA for short. Acetate fiber is divided into diacetate fiber and triacetate fiber, which is a type of man-made fiber. Chemical fibers are made from cellulose as raw material and converted into cellulose acetate through chemical synthesis. First prepared in 1865, it is an acetate ester of cellulose. A thermoplastic resin obtained by esterifying cellulose with acetic acid or acetic anhydride under the action of a catalyst. It is a chemically modified natural polymer obtained by esterifying the hydroxyl groups in the cellulose molecule with acetic acid. Its properties depend on the degree of acetylation.
01 Classification of acetate fiber
It can be divided according to the degree of substitution of hydroxyl groups by acetyl groups in cellulose. For diacetate fiber and triacetate fiber.
Diacetate is a type of acetate formed after partial hydrolysis, and its degree of esterification is lower than that of triacetate. Therefore, the heating performance is not as good as that of trivinegar, the dyeing performance is better than that of trivinegar, and the moisture absorption rate is higher than that of trivinegar.
Triacetate is a type of acetate that does not undergo hydrolysis and has a high degree of esterification. 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 glucose ring of cellulose 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. The supramolecular structure of diacetate fiber has a larger amorphous area, while triacetate fiber has a certain crystalline structure, and the symmetry, regularity, and crystallinity of the fiber macromolecules are higher than those of diacetate fiber.
02 The structure of acetate fiber
Longitudinal fiber surface morphology is smooth , relatively uniform, with obvious grooves; as can be seen from its cross-sectional shape, the fiber has no skin-core structure and is in the shape of a clover leaf, with a relatively smooth periphery and few shallow serrations.
03 Properties of acetate fiber
Chemical properties
1. Resistance to alkali and weak alkaline alkali The agent basically caused no damage to the acetate fiber, and the weight loss rate of the fiber was very small. After encountering strong alkali, especially diacetate fiber, it is prone to deacetylation, resulting in weight loss, strength and modulus. Therefore, the pH value of the solution used to treat 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 perchlorethylene.
2. Resistance to organic solvents: Cellulose acetate is completely soluble in acetone, DMF, and glacial acetic acid, but is insoluble in ethanol and tetrachlorethylene. Based on these characteristics, acetone can be used as a spinning solvent for acetate fiber, and tetrachlorethylene can be used for dry cleaning of acetate fiber fabric.
3. Acid-resistant acetate fiber has good acid-resistant stability. 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 Soluble in concentrated sulfuric acid, concentrated hydrochloric acid, and concentrated nitric acid.
4. Although dyeable acetate fiber 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, cellulose fiber The dyes commonly used for dyeing have almost no affinity for acetate fiber and are 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 level dyeing effect, high dye exhaustion rate, high color fastness, and complete color spectrum.
Physical properties
1. Acetate fiber not only has a certain degree of water absorption, but also has the ability to be quickly removed after absorbing water;
2. The thermal stability of acetate fiber is good. The glass transition temperature of the fiber is around 185 ℃, and the melting termination temperature is around 310 ℃. At the end of the heating, the weight loss rate of the fiber is 90.78%; the breaking strength of acetate fiber is 1.29 cN. /dtex, and the strain is 31.44%;
3. The density of acetate fiber is smaller than that of viscose fiber, and closer to polyester; its strength is the lowest among the three fibers;
4. The elasticity of acetate fiber is relatively good, similar to silk and wool; 5. The shrinkage rate of boiling water is low, but high-temperature treatment will affect the strength and gloss of the fiber, so the temperature should not exceed 85°C.
04 Is acetate fabric comfortable to wear?
1. Divinegar has good breathability and antistatic properties
In an environment with a relative humidity of 65%, diacetyl vinegar has the same hygroscopicity as cotton and better quick-drying performance than cotton. Therefore, it can well absorb the water vapor evaporated by the human body and discharge it well at the same time. Thus making people feel comfortable. At the same time, good hygroscopic performance��Reduce the accumulation of static electricity and make it less likely to produce static electricity.
2. Second vinegar has a soft touch
Initial modulus diagram of △ fiber
Initial modulus The fiber content is low, and the fiber is weakly rigid and easy to bend under a slight load, showing a soft character, thus giving the skin a smooth, soft and comfortable feel. But if the initial modulus is too low, it will appear weak.
The initial modulus is high, and the fiber has strong rigidity and is not easy to bend under a small load, showing a stiff character.
3. Divinegar has outstanding deodorizing performance
△Deodorizing performance of diacetyl vinegar, cupro, cotton and polyester Comparison chart
△Comparison chart of deodorizing performance of diacetate, cupro, cotton and polyester (2)
05 Acetate fiber Why does fabric look good?
1. Divinegar has a pearl-like soft luster
△The structure of mulberry silk, acetate fiber and polyester
Mulberry silk horizontal The cross section of acetate fiber is irregularly triangular, and the cross section of acetate fiber is irregularly concave and convex. Both have longitudinal stripes on their longitudinal sections, making the transverse light diffusely reflected and the longitudinal light also diffusely reflected. The refractive index is lower, 1.48. Therefore, mulberry silk has a pearl-like soft luster.
2. Acetate fiber has excellent drapability. The initial fiber modulus is 30-45cn/dtex, the rigidity is weak, and the cross-section is irregular concave and convex. The fabric is soft and has good drape.
3. Divinegar has bright and bright colors and color fastness
△Color fastness comparison chart of each fiber when saturated with color (grade)
Acetate fiber color, The color spectrum is complete, the color is full and pure, and the color fastness is excellent.
4. Acetate fiber has good dimensional stability
Fiber acetate has low expansion to moisture, so after being made into fabric Good dimensional stability, maintains the appearance of clothes.
5. Divinegar has relatively balanced antifouling properties
For stains with three ingredients: dust, water-based, and oil-based, it is not easy to stain and easy to clean. nature. </p
