Cellulose triacetate

Cellulose triacetate, (triacetate, CTA or TAC) is a chemical compound produced from cellulose and a source of acetate esters, typically acetic anhydride. Triacetate is commonly used for the creation of fibres and film base. It is chemically similar to cellulose acetate. Its distinguishing characteristic is that in triacetate, at least "92 percent of the hydroxyl groups are acetylated." During the manufacture of triacetate, the cellulose is completely acetylated; whereas in normal cellulose acetate or cellulose diacetate, it is only partially acetylated. Triacetate is significantly more heat resistant than cellulose acetate.
History.
Triacetate, whose chemical equation is [C6H7O2(OOCCH3)3]n, was first produced commercially in the U.S. in 1954 by Celanese Corporation. Eastman Kodak was a manufacturer of CTA until March 15, 2007. For almost 3 years, Mitsubishi Rayon Co. Ltd. was the only manufacturer. In 2010, Eastman Chemical announced a 70% increase in cellulose triacetate output at its Kingsport (TN) manufacturing site to achieve the increasing demand for the chemical's use as an intermediate in the production of polarized films for liquid crystal displays.
Production.
Triacetate is derived from cellulose by "acetylating" cellulose with acetic acid and/or acetic anhydride. Acetylation converts hydroxyl groups in cellulose to acetyl groups, which renders the cellulose polymer much more soluble in organic solvents. The cellulose acetate is dissolved in a mixture of dichloromethane and methanol for spinning. As the filaments emerge from a spinneret, the solvent is evaporated in warm air, in a process known as dry spinning, leaving a fibre of almost pure triacetate.
A finishing process called "S-Finishing" or surface saponification is sometimes applied to acetate and triacetate fabrics using a sodium hydroxide solution. This removes part or all of the acetyl groups from the surface of the fibres leaving them with a cellulose coating. This reduces the tendency for the fibres to acquire a static charge.
Chemistry.
CAS number 9012-09-3
Applications.
As a fibre.
Triacetate fibres have a crenate cross section.
Usage scenarios.
Triacetate is particularly effective in clothing where crease or pleat retention is important, such as skirts and dresses.
In the 1980s triacetate was also used with polyester to create shiny tracksuits. The fabric was smooth and shiny on the outside and soft and fleecy on the inside.