Method of Applying Phase Transition Materials to Semi-Porous, Flexible Substrates Used to Control Gas Permeability

摘要

Method of applying phase transition substance to impart reduced ignition propensity to a smoking article comprising a tobacco column and a wrapper surrounding the tobacco column and having a porous structure with a base permeability. The method comprising forming a pattern of phase transition material on the wrapper such that, when subjected to the heat of the tobacco column burning firecone, the phase transition material at least partially fills the wrapper porous structure in the vicinity of the burning firecone to form an area on the wrapper having reduced permeability lower than that of the wrapper base permeability. The reduced permeability of the wrapper in the vicinity of the burning firecone imparts reduced ignition propensity such that there is insufficient air flow to sustain combustion of the firecone or insufficient air flow to sustain an intensity of the burning firecone necessary to ignite the substrate.