Coated plug wrap to enhance filter hardness

Abstract

A method for enhancing hardness of a filter (30) for a smoking article (10) includes disposing a plug wrap (60) about filter material; and applying a hardness-enhancing coating composition to the plug wrap after the plug wrap has been disposed about the filter material to enhance the hardness of the filter.

1 . A smoking article comprising:
 smokable material; and   a filter down stream of the smokable material, the filter comprising filter material and a plug wrap disposed about the filter material,
 wherein the plug wrap comprises an inner surface facing towards a longitudinal axis of the filter and an outer surface facing away from the longitudinal axis of the filter, wherein the outer surface of the plug wrap comprises a hardness enhancing coating, wherein the filter has an average radial hardness of at least 2% greater than filters that are essentially the same except that the filters have a plug wrap to which the coating is not applied. 
   
     
     
         2 . The smoking article according to  claim 1 , wherein the filter has a longitudinal hardness that is at least 2N greater than a filter having a plug wrap to which the coating is not applied. 
     
     
         3 . The smoking article according to  claim 1 , wherein the filter has a radial hardness that is at least 2% greater than a filter having a plug wrap to which the coating is not applied. 
     
     
         4 . The smoking article according to  claim 1 , wherein the coating has a thickness between 2 micrometers and 200 micrometers. 
     
     
         5 . The smoking article according to  claim 1 , wherein the coating comprises polyvinyl alcohol. 
     
     
         6 . The smoking article according to  claim 5 , wherein the polyvinyl alcohol has a molecular weight in a range from 40 to 125,000 grams/mol. 
     
     
         7 . The smoking article according to  claim 1 , wherein the coating is applied as a strip having a width of 5 millimeters or greater. 
     
     
         8 . The smoking article according to  claim 1 , wherein the coating is applied to the entire outer surface of the plug wrap. 
     
     
         9 . A method for enhancing hardness of a filter for a smoking article comprising:
 disposing a plug wrap about filter material; and   applying a hardness-enhancing coating composition to the plug wrap after the plug wrap has been disposed about the filter material to enhance the hardness of the filter.   
     
     
         10 . The method according to  claim 9 , wherein the coating composition comprises polyvinyl alcohol having a solid content from 10% to 70%. 
     
     
         11 . The method according to  claim 9 , wherein the coating composition consists essentially of polyvinyl alcohol. 
     
     
         12 . The method according to  claim 9 , wherein the coating composition is applied to the plug wrap at a rate from 20 meters/min to 50 meters/min. 
     
     
         13 . The method according to  claim 9 , further comprising curing of the coated filter to remove solvent from the applied coating composition. 
     
     
         14 . The method according to  claim 13 , wherein the drying occurs at ambient temperature. 
     
     
         15 . The method according to  claim 13 , wherein the coating composition is applied to the plug wrap in an amount sufficient to produce a coating layer having a thickness is a range from 2 micrometers to 200 micrometers after the filter is dried.