A Cigarette filter is a component of the cigarette, together with cigarette paper, capsules and adhesives. The filter might be made from cellulose acetate fibre, paper or activated charcoal (either like a cavity filter or embedded to the cellulose acetate). Macroporous phenol-formaldehyde resins and asbestos are also found in cigarette filters The acetate and paper get a new particulate smoke phase by particle retention (filtration), and finely divided carbon modifies the gaseous phase (adsorption). Filters is able to reduce “tar” and nicotine smoke yields around 50%, using a greater removal rate for other classes of compounds (e.g., phenols), however are ineffective in filtering toxins such as deadly carbon monoxide. Most factory-made cigarettes have a filter; those who roll their own can purchase them from the tobacconist.
Cellulose acetate is manufactured by esterifying bleached cotton or wood pulp with acetic acid. In the three cellulose hydroxy groups intended for esterification, between two and three are esterified by controlling the level of acid (level of substitution (DS) 2.35-2.55). The ester is spun into fibers and formed into bundles called filter tow. Flavors (menthol), sweeteners, softeners (triacetin), flame retardants (sodium tungstate), breakable capsules releasing flavors at the moment, and additives colouring the cigarettes could be put into cigarette filters. The 5 largest manufactures of filter tow are Hoechst-Celanese and Eastman Chemicals in the us, Rhodia Acetow in Germany, Daicel in Japan, and Courtaulds in england.
Starch glues or emulsion-based adhesives can be used gluing cigarette seams. Hot-melt and emulsion-based adhesives can be used filter seams. Emulsion-based adhesives can be used bonding the filters to the cigarettes.
Cellulose acetate is non-toxic, odorless, tasteless, and weakly flammable. It is resistant to weak acids and is largely stable to mineral and fatty oils in addition to petroleum. It can be biodegradable and the raw materials are a renewable natural polymer likely to find application for other uses down the road. Smoked cigarette butts contain 5-7 mg nicotine (about 25% from the total cigarette nicotine content), children ingesting >2 whole cigarettes, 6 cigarette butts or possibly a total of 0.5 mg/kg of nicotine must be admitted to a hospital. Cellulose acetate is hydrophilic and retains the water-soluble smoke constituents, ones lots of people are irritating (acids, alkali, aldehydes, and phenols), while letting from the lipophilic aromatic compounds.
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