A Cigarette filter is a component of an cigarette, along with cigarette paper, capsules and adhesives. The filter may be produced from cellulose acetate fibre, paper or activated charcoal (either being a cavity filter or embedded to the cellulose acetate). Macroporous phenol-formaldehyde resins and asbestos are also used in cigarette filters The acetate and paper change the particulate smoke phase by particle retention (filtration), and finely divided carbon modifies the gaseous phase (adsorption). Filters can help to eliminate “tar” and nicotine smoke yields around 50%, which has a greater removal rate for other classes of compounds (e.g., phenols), but they are ineffective in filtering toxins like carbon monoxide. Most factory-made cigarettes come with a filter; those that roll their particular can buy them from the tobacconist.
Cellulose acetate is manufactured by esterifying bleached cotton or wood pulp with acetic acid. In the three cellulose hydroxy groups available for esterification, between two and three are esterified by controlling the volume of acid (amount 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 on demand, and additives colouring the cigarette could be put into cigarette filters. The five largest manufactures of filter tow are Hoechst-Celanese and Eastman Chemicals in america, Rhodia Acetow in Germany, Daicel in Japan, and Courtaulds in the United Kingdom.
Starch glues or emulsion-based adhesives are used for gluing cigarette seams. Hot-melt and emulsion-based adhesives are used for filter seams. Emulsion-based adhesives are used for bonding the filters for the cigarettes.
Cellulose acetate is non-toxic, odorless, tasteless, and weakly flammable. It is proof against weak acids and is largely stable to mineral and fatty oils as well as petroleum. It’s biodegradable along with the raw material is a renewable natural polymer supposed to find application for other uses in the foreseeable future. Smoked cigarette butts contain 5-7 mg nicotine (about 25% in the total cigarette nicotine content), children ingesting >2 whole cigarettes, 6 cigarette butts or even a total of 0.5 mg/kg of nicotine ought to be admitted to a hospital. Cellulose acetate is hydrophilic and retains the water-soluble smoke constituents, that many are irritating (acids, alkali, aldehydes, and phenols), while letting through the lipophilic aromatic compounds.
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