Smoking article with improved extinguishing characteristcs

Abstract

A smoking article includes a tobacco rod and a wrapper, wherein the wrapper includes at least one zone treated with an inorganic salt providing reduced ignition propensity. Preferably, the porosity of the wrapper in the treated zones is larger than 10 CU. Suitable inorganic salts are, e.g., magnesium chloride, aluminum sulfate, alum, sodium tetraborate, the hydrated forms of these compounds, sodium chloride, or mixtures thereof.

1 . A smoking article comprising:
 a tobacco rod; and   a wrapper,   said wrapper including at least one zone treated with an inorganic salt providing reduced ignition propensity.   
   
   
       2 . The smoking article as claimed in  claim 1 ,
 said treated zone having a porosity greater than 10 Coresta units.   
   
   
       3 . The smoking article as claimed in  claim 1 ,
 said inorganic salt comprising at least one substance selected from the group consisting of magnesium chloride, aluminum sulfate, alum, sodium tetraborate, hydrated magnesium chloride, hydrated aluminum sulfate, hydrated alum, hydrated sodium tetraborate, and sodium chloride.   
   
   
       4 . The smoking article as claimed in  claim 1 ,
 said inorganic salt in the treated zone of the wrapper being present in an amount having a range of from 0.2 mg/cm 2  to 20 mg/cm 2 .   
   
   
       5 . The smoking article as claimed in  claim 1 ,
 said wrapper including a plurality of discrete zones treated with the inorganic salt,   said discrete zones presenting a total treated area that is smaller than the total surface area of the wrapper.   
   
   
       6 . The smoking article as claimed in  claim 5 ,
 said discrete zones being arranged as bands extending along the circumference of the smoking article,   each band having a width, measured along an axis of the tobacco rod, of from 2 mm to 12 mm.   
   
   
       7 . The smoking article as claimed in  claim 6 ,
 said wrapper including at least two discrete zones,   adjacent ones of said zones being separated by at least 1 mm.   
   
   
       8 . The smoking article as claimed in  claim 1 ,
 said smoking article further comprising a filter.   
   
   
       9 . The smoking article as claimed in  claim 1 ,
 wherein the smoking article is a cigarette,   said wrapper being a cigarette paper.   
   
   
       10 . A method of manufacturing a smoking article as defined in  claim 1 , said method comprising the steps of:
 applying the inorganic salt to the wrapper by a solution or a suspension.   
   
   
       11 . The manufacturing method as claimed in  claim 10 ,
 said solution being heated to improve the solubility of the inorganic salt.   
   
   
       12 . The manufacturing method as claimed in  claim 10 ,
 said solution solvent or suspension agent comprising water.   
   
   
       13 . The manufacturing method as claimed in  claim 10 ,
 said applying step including applying the inorganic salt to the wrapper by a technique selected from the group consisting of gravure printing, inkjet printing, spraying, and sizing.   
   
   
       14 . The manufacturing method as claimed in  claim 10 ,
 said applying step including applying the inorganic salt to the wrapper by sizing in a papermaking process for providing the material of the wrapper.   
   
   
       15 . The manufacturing method as claimed in  claim 10 , further comprising the steps of:
 providing the material of the wrapper by a papermaking process; and   cutting a mother reel into bobbins containing wrapper material,   said applying step being performed immediately after said providing step and simultaneously with said cutting step.   
   
   
       16 . The manufacturing method as claimed in  claim 10 ,
 said applying step including applying the inorganic salt to the wrapper during an offline rewinding step of a bobbin containing wrapper material.   
   
   
       17 . The manufacturing method as claimed in  claim 10 ,
 said applying step including applying the inorganic salt to the wrapper online in a cigarette making process; and   wrapping a continuous tobacco rod with the wrapper material,   said applying step being performed before said wrapping step.   
   
   
       18 . The manufacturing method as claimed in  claim 10 ,
 said applying step including applying the inorganic salt to the wrapper online in a cigarette making process; and   wrapping a continuous tobacco rod with the wrapper material,   said applying step being performed after said wrapping step.   
   
   
       19 . A paper forming a wrapper for rolling a cigarette that includes a tobacco rod, wherein the wrapper is configured to radially surround the rod, said paper comprising:
 at least one zone treated with an inorganic salt providing reduced ignition propensity.   
   
   
       20 . The paper as claimed in  claim 19 ,
 said paper being formed as a tube,   said tube including a filter.