Filter materials and filters made therefrom

Abstract

The present invention relates to filter material for inclusion in a smoking article, wherein the filter material is in the form of a fibrous tow or a non-woven sheet comprising fine cellulose acetate fibres having a mean diameter of from about 1 μm to about 15 um. The invention also relates to processes for preparing filter material for inclusion in a smoking article, the filter material comprising fine cellulose acetate fibres having a mean diameter of from about 1 μm to about 15 μm. The invention further relates to filters or filter elements comprising the filter material, smoking articles comprising the same, and use of the filter material in smoke filtration.

1 . A filter material for inclusion in a smoking article, wherein the filter material is in the form of a fibrous tow comprising fine cellulose acetate fibres having a mean diameter of from about 1 μm to about 10 μm. 
     
     
         2 . A filter material as claimed in  claim 1 , wherein the tow is formed from fibres and at least about 80% by weight of the fibres are fine cellulose acetate fibres. 
     
     
         3 . A filter material as claimed in  claim 1 , wherein the fine cellulose acetate fibres have a diameter of no less than 0.3 μm. 
     
     
         4 . A filter material as claimed in  claim 1 , wherein the fine cellulose acetate fibres comprise cellulose acetate and an additive. 
     
     
         5 . A filter material as claimed in  claim 1 , wherein filter material further comprises a plasticizer which is one or more selected from the group consisting of: triacetin; polyethylene glycol; triethyl citrate; and
 triethylene glycol diacetate.   
     
     
         6 . A filter material as claimed in  claim 1 , wherein the filter material removes from about 50% to about 90% phenol from tobacco smoke. 
     
     
         7 . A filter material as claimed in  claim 1 , wherein the filter material removes from about 50% to about 90% cresol from tobacco smoke. 
     
     
         8 . A process for preparing filter material for inclusion in a smoking article, the filter material comprising fine cellulose acetate fibres having a mean diameter of from about 1 μm to about 10 μm, the process comprising electrospinning or centrifugal spinning or melt spinning. 
     
     
         9 . A process as claimed in  claim 8 , wherein a cellulose acetate solution is spun, the solution having a cellulose acetate concentration of from about 6% to about 30%. 
     
     
         10 . A process as claimed in  claim 8 , wherein the fine cellulose acetate fibres are produced by spinning through a spinneret using centrifugal force, and the spinneret spins at a rate of from about 4500 to about 7500 rpm. 
     
     
         11 . A process as claimed in  claim 8 , wherein the flow rate of the cellulose acetate solution through the orifice(s) of the spinneret is from about 5 to about 100 ml/min. 
     
     
         12 . A process as claimed in  claim 8 , wherein the fine cellulose acetate fibres are laid down as a non-woven sheet or non-woven web directly following spinning. 
     
     
         13 . A process as claimed in  claim 12 , wherein the fine cellulose acetate fibres are drawn onto a base sheet upon which a non-woven sheet or web is formed by a vacuum pull, by air flow or by electrostatic charge. 
     
     
         14 . A filter material obtained or obtainable by a process as claimed in  claim 8 . 
     
     
         15 . A filter element or filter for a smoking article, comprising a filter material as claimed in  claim 1 , or comprising a filter material obtained or obtainable by a process for preparing filter material for inclusion in a smoking article, the filter material comprising fine cellulose acetate fibres having a mean diameter of from about 1 μm to about 10 μm, the process comprising electrospinning or centrifugal spinning or melt spinning. 
     
     
         16 . A filter as claimed in  claim 15 , wherein the filter has a pressure drop of from about 60 to about 140 mmWG. 
     
     
         17 . A filter as claimed in  claim 15  comprising from about 30 to about 90 mg of filter material in the form of a fibrous tow comprising fine cellulose acetate fibres having a mean diameter of from about 1 μm to about 10 μm. 
     
     
         18 . A filter as claimed in  claim 17 , comprising from about 40 to about 80 mg of said filter material. 
     
     
         19 . A smoking article comprising a filter or filter element as claimed in  claim 15 . 
     
     
         20 . A filter material as claimed in  claim 1  configured for filtration of tobacco smoke.