Cellulose triacetate

Cellulose triacetate, also known simply as triacetate, is manufactured from cellulose and acetate. Triacetate is typically used for the creation of fibres and film base. It is similar chemically to cellulose acetate, with the distinguishing characteristics being that in triacetate, according to the Federal Trade Commission definition, at least "92 percent of the hydroxyl groups are acetylated." During the manufacture of triacetate the cellulose is completely acetylated whereas in regular cellulose acetate or cellulose diacetate, it is only partially acetylated. Triacetate is significantly more heat resistant than cellulose acetate.

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History

Triacetate was first the produced commercially in the U.S. in 1954 by Celanese Corporation [1]. Mitsubishi Rayon Co., Ltd. is the only company that still produces the fiber. Eastman Kodak formerly manufactured cellulose triacetate. They discontinued this product on March 15, 2007.

Production

Triacetate is derived from cellulose by combining cellulose with acetate from acetic acid and acetic anhydride. 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

As a Fibre

Triacetate fibres have a crenate[2] cross section.

Characteristics

• Shrink resistant
• Wrinkle resistant
• Easily washable
• Generally washable at high temperatures
• Maintains creases and pleats well

Usage Scenarios

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 which were very popular at the time. The material was very smooth and shiny on the outside and soft and fleecy on the inside.

General Care Tips

• Ironable up to 200 °C
• Pleated garments are best hand laundered. Most other garments containing 100% triacetate can be machine washed and dried
• Articles containing triacetate fibres require very little special care due mainly to the fibre's resistance to high temperatures

As a film

Characteristics

• Resistant to grease, oil, aromatic hydrocarbons, and most common solvents
• Films have hard glossy surfaces
• Excellent optical clarity
• High dielectric constant
• Easily laminated, coated, folded, and die-cut
• Cellulose acetate film prone to degradation known as Vinegar syndrome

Usage Scenarios

• Polarizer films for LCD projectors
• Specialized overhead projector transparencies
• Specialized photographic film
• Motion picture film
• Production of animation cels
• Packaging

See also

• Cellulose acetate
• Vinegar syndrome
• Rayon

References

• www.fibersource.com description of triacetate fibre
• www.islandgroup.com description of triacetate film
• Federal Trade Commission definition of triacetate
• Article on the long term archival of triacetate photographic films
• Glossary of terms relation to the manufacture of cellulose / acetate fibres