Introduction
Cellulose acetate, which is also called CA, is irreplaceable for cigarette filters manufacturing due to its significant properties. It is a kind of synthetic fibre. Textile fibres which consist of ester cellulose are called acetate fibres, acetate’s forming substance is the cellulose acetate. Acetate is the main row material for most cigarette filters.
Though CA is the main material in making cigarette filters, it has many other applications. For example, it is also used widely in the clothing industry, as well as it was applied to manufacture aircraft windows. Its wide application is based on its chemical stability and reliable safety guarantee.
figure 1 [1]
Manufacture
The manufacturing process of CA includes dissolving, drying, crimping and so on. A reaction vessel is required. Briefly speaking, first, the cellulose is acetylated in the reaction vessel, and so that cellulose triacetate forms, which will be hydrolyzed to get cellulose diacetate. By dissolving and spinning, the diacetate cellulose fibre is obtained.
Cigarette Filter Made of Cellulose Acetate[2]
Application
In the past, CA was used as a synthetic fibre. Then in 1934, CA was used as a kind of film to take the place of cellulose nitrate. What’s more, in 1952, the cellulose acetate magnetic tape was created, which replaced the metal tape.
Nowadays, CA is used to make the filter of cigarettes dominatingly. But you can still find some tool handles and steering wheel covers which consists of CA as well.[2]
Since the abundance and renewable property of CA, CA is regarded to be an ideal material for filter manufacturing. In the future, CA will be used for 2 aspects below.
First, a novel NH2-functionalized cellulose acetate/silicon composite nanofibrous membrane, which has the ability of adsorption, will be used for wastewater treatment.[3]
The second one is cellulose bead. By dispersion and chemical reaction, we can use CA to get cellulose bead.[4]
History[5]
Cellulose acetate has been used as raw material for a long time in many different fields such as plastics, membrane and the textile industry. Cellulose acetate was considered as a critical material for plastics and textiles for many years. Even though in its applications for plastics and textiles, it was replaced by polymer slowly, the demand for cellulose acetate has been increasing especially for Filter Tow in cigarettes filters.
CA was first discovered by Paul Schützenberger in 1865 when he heated cellulose mixed with acetic anhydride. Then in 1904, George Miles, an American chemist, found that other solvents like acetone could be used to dissolve CA. What’s more, a chemist from Germany called Eduard Schweizer discovered tetraaminecopper dihydroxide could dissolve cellulose as well.
Acetate was introduced for the first time in 1904 by Camille Dreyfus and his brother Henri, who used CA in manufacturing fibres as well as textile use. In the next 5 years, the Dreyfus brothers studied and tested a lot about CA and they opened a factory which could produce 3 tons of perfect acetate lacquers a day. These products were sold well. Later, acetate lacquer, which was called “dope”, was used in the aviation industry.
By 1913, having done more than 20,000 experiments, the brothers successfully produced specimens of acetate continuous filament yarn.
A famous company was called Mazzucchelli Spa is now the biggest company producing Celluloid Acetate sheets and Cellulose Nitrate sheets in the world. The main application of CA in this company is to make the frames of glasses, hair ornaments and jewellery.
CA was first used for cigarette filter tow manufacturing in 1952. Since then, the demanding of CA in this field has been increasing stably, which is shown in Figure 2.
Figure 2. Development of the worldwide CA Filter Tow Market
Nowadays, about 95% of the cigarettes in the world are sold with a filter made of CA. That is because of the great properties of CA, which will be talked in detail in the next part.