Acetate Fibers

one of the principal types of synthetic fibers; they are obtained from cellulose acetate. Depending on the type of starting raw material, there are triacetate fibers (from triacetate cellulose) and the acetate fibers themselves (from partially saponified, so-called secondary cellulose acetate).

Acetate fibers are molded from solutions of cellulose acetate in organic solvents (triacetate cellulose in a mixture of methylene chloride and alcohol, secondary cellulose acetate in acetone), usually by the so-called dry method. By this method filaments, the so-called acetate silk, are obtained. In the process of obtaining staple acetate fibers, molding takes place by the dry or the wet method.

Because acetate fibers are twice as elastic as viscose and cuprammonium fibers, fabrics made from them are noted for crinkle resistance. Moreover, acetate fibers are soft and pleasant to the touch and pass ultraviolet rays. Acetate fibers are dyed only with special types of dyes, which are unsuitable for most other fibers. This makes it possible to obtain a variety of color effects on the articles made from blends of acetate fibers and other fibers. Triacetate fibers are characterized by lower hygroscopicity but greater elasticity and crinkle resistance than articles made of acetate fibers. At 65 percent relative humidity, triacetate fibers absorb 2.5–3 percent moisture, while acetate fibers absorb 6–7 percent.

The tensile strength of acetate fibers is low (breakage distance, 11–13 km). The loss of strength upon moist testing is 40–45 percent for acetate fibers and 15–20 percent for triacetate fibers. Acetate fibers are characterized by low thermal stability: at temperatures higher than 160–170°C the shape of articles made of these fibers changes; at 210°C, their thermal decomposition begins to occur. For this reason, articles made of acetate fibers can be ironed only through a damp cloth. Acetate fibers have low stability in the presence of dilute solutions of alkalis. The disadvantages of acetate fiber articles also include their low durability and high tendency to gather static electricity. To offset and remedy these deficiencies, chemical methods for the modification of cellulose acetates are used.

Acetate fibers are used principally in the production of general consumer articles (outer clothing, lingerie, and lining and dress fabrics). The staple acetate fibers are used as partial substitutes for wool in the manufacture of fine fabrics and various kinds of knitwear. The use of acetate fibers reduces shrinkage. Triacetate water-repellent threads are used as electric insulating material.

Acetate fiber production developed rapidly until 1957 because of the harmlessness and simplicity of industrial production, the fiber’s valuable properties, and the inexpensive raw material. Later acetate fiber production decreased after the appearance of new types of valuable synthetic fibers. In 1967 the world output of acetate fibers was 397,000 tons, 6.4 percent of the total production of chemical fibers.