POLYVINYL ALCOHOL TOBACCO SMOKE FILTERS AND PRODUCTS USING SUCH FILTERS, AND METHODS AND APPARATUS FOR MAKING SAME

摘要

A porous element (20) particularly for use as a tobacco smoke filter plug in association with a cigarette (16) or the like wherein the matrix comprises a multiplicity of biodegradable polyvinyl alcohol fibers bonded together at their points of contact to define a tortuous interstitial path for the passage of smoke. Because of the hygroscopic nature of polyvinyl alcohol, commercial production of such products require careful control of the moisture content of the polyvinyl alcohol fiber starting material, usually pre-drying the same to residual moisture content of 7 % by weight or less, and treatment of the low moisture fibrous mass by superheated steam to add about 2.5 to 5 % moisture to a final moisture content of about 2.5 to 10 %. The steam renders the fiber surface adhesive and, thus, bondable, and also lubricates the gathered fibers to improve processability.