Tobacco Smoke Filter

Abstract

A tobacco smoke filter containing a high activity activated carbon impregnated with a metal impregnant. The use of a relatively low level of impregnant, in combination with a base carbon having higher activity than that use in standard cigarette filters, is highly effective in removing HCN from cigarette smoke.

1 . A tobacco smoke filter containing activated carbon impregnated with a metal impregnant, wherein the activated carbon is high activity activated carbon.  
     
     
         2 .- 26 . (canceled)  
     
     
         27 . A tobacco smoke filter according to  claim 1 , wherein the metal impregnant is one or more of copper, molybdenum, manganese, cobalt, zinc and iron.  
     
     
         28 . A tobacco smoke filter according to  claim 1 , wherein the metal impregnant(s) is present in an amount which is not more than 10% of the dry weight of the high activity activated carbon.  
     
     
         29 . A filter according to  claim 28 , wherein the metal impregnant(s) is present in an amount which is from 1 to 5% of the dry weight of the activated carbon.  
     
     
         30 . A tobacco smoke filter according to  claim 1 , wherein the metal impregnant is copper.  
     
     
         31 . A tobacco smoke filter containing activated carbon which is impregnated with copper and molybdenum, wherein the ratio of copper to molybdenum is greater than 1.3 to 1.  
     
     
         32 . A tobacco smoke filter containing activated carbon which is impregnated with copper and molybdenum, wherein the activated carbon is a high activity activated carbon.  
     
     
         33 . A filter according to  claim 1 , wherein the activated carbon has an activity of greater than 90% CTC prior to impregnation.  
     
     
         34 . A filter according to  claim 1 , wherein the activated carbon has an activity of greater than 100% CTC prior to impregnation.  
     
     
         35 . A filter according to  claim 1 , wherein the activated carbon has an activity of greater than 80% CTC after impregnation.  
     
     
         36 . A filter according to  claim 1 , wherein the activated carbon has an activity of greater than 90% CTC after impregnation.  
     
     
         37 . A filter according to  claim 1 , in which substantially all of the activated carbon is of particle size between 2 mm and 0.15 mm, preferably between 0.6 mm and 0.212 mm.  
     
     
         38 . A filter according to  claim 1 , which contains between 10 mg and 150 mg of activated carbon, preferably between 30 mg and 60 mg of activated carbon.  
     
     
         39 . A filter according to  claim 1 , which further comprises one or more additional adsorbents.  
     
     
         40 . A filter according to  claim 39 , wherein the additional adsorbent(s) selectively removes a compound(s) present in the VP fraction of cigarette smoke other than HCN.  
     
     
         41 . A filter cigarette comprising a filter according to  claim 1  joined at its upstream end to a wrapped tobacco rod.