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AssigneeFiltrona International Limited
InventorRichard M. Berger
Estimating the term…
A porous element particularly for use as a tobacco smoke filter plug in association with a cigarette 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 a 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.
In a substantially self-sustaining shaped porous element comprising a three-dimensional matrix formed of continuous polymeric fibers bonded to each other at spaced points of contact to define interstitial spaces therebetween forming a tortuous path therethrough, the improvement which comprises:
In a method of making self sustaining porous elements including the steps of providing a multiplicity of continuous polymeric fibers with the fibers contacting each other at spaced points, gathering the fibers into a rod-like formation, heating the gathered fibers to render the same bondable at the spaced points of contact, cooling the resultant element to form a continuous rod, and subdividing the rod to form discrete elements each of which comprises a porous matrix formed by the fibers and defining a tortuous interstitial path therethrough, the improvement comprising:
In an apparatus for making self-sustaining porous element including means for providing a continuous filamentary tow formed of a multiplicity of polymeric fibers with the fibers contacting each other at spaced points, means for gathering the fibers into a rod-like formation, means for heating the gathered fibers to render the same bondable at the spaced points of contact, means for cooling the resultant element to form a continuous rod, and means for subdividing the rod to form discrete elements each of which comprises a porous matrix formed by the fibers and defining a tortuous interstitial path therethrough, the improvement comprising:
Dependencies are inferred from the claim text.