Fiber Basics: Acetate

Acetate fiber was born in the early 20th century. It was successfully trial-produced and industrialized in the United Kingdom in the early 1920s. It is currently the second largest…

Acetate fiber was born in the early 20th century. It was successfully trial-produced and industrialized in the United Kingdom in the early 1920s. It is currently the second largest variety among cellulose fibers after viscose fiber. Acetate fiber can be used to make textiles, cigarette filters, film bases, plastic products, etc.

1. Introduction to acetate fiber

Cellulose acetate, the English name is cellulose acetate, referred to as CA. 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. to

2. Classification of acetate fiber

According to the degree of substitution of hydroxyl groups by acetyl groups in cellulose, it can be divided into diacetate fiber and triacetate fiber.

Diacetate is formed after partial hydrolysis of type 1 acetate, 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.

3. Structure of acetate fiber

The surface shape of the longitudinal fiber is smooth and relatively uniform, with obvious grooves; from its cross-sectional shape, it can be seen that 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.

4. Chemical properties of acetate fiber

1. Alkali resistance

Weak alkaline alkaline agents basically do not cause damage to acetate fiber, and the weight loss rate of the fiber is 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 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 resistance

Acetate fiber has good acid resistance and 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 be dissolved in concentrated sulfuric acid, concentrated hydrochloric acid, and concentrated nitric acid.

4. Dyeability

Although 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, dyes commonly used for dyeing cellulose fibers have almost no affinity for acetate fiber. , 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 colors, good level dyeing effect, high dye exhaustion rate, high color fastness, and complete color spectrum.

(Hangzhou Zhuoda: Dispersed direct-injection digital printing on acetate fabrics)

5. Physical properties of acetate fiber

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 should be 31.44%.

3. The density of acetate fiber is smaller than that of viscose fiber, and closer to that of polyester; its strength is the lowest among the three fibers.

4. Acetate fiber has relatively good elasticity, similar to silk and wool.

5. Boiling water shrinks�� is low, but high-temperature treatment will affect the strength and gloss of the fiber, so the temperature should not exceed 85 ℃.

6. Recommendations for acetate disperse dyes:


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Author: clsrich