Cigarette paper is treated by one or the other of two alternative processes. The first alternative process is characterized by the step of coating between 40 and 100% of the surface area of the paper with an aqueous alkali metal silicate solution, the SiO.sub.2 concentration of which ranges from between 12 and 16% for 40% coverage to between 7 and 15% for full coverage. The second alternative process is characterized by two sequential uniform coatings of an aqueous alkali metal silicate solution, the SiO.sub.2 concentrations in each solution ranging from 1.7% to 6%.
This invention concerns the use of a class of coatings that are applied to the paper wrapper that encloses the cigarette's smoking medium, for limiting in a predictable manner the free burning time of the treated cigarette, or controlling the lapsed time prior to self-extinguishment after being lit and left unattended. The coating materials are generally identified as polymeric chlorine-containing film-forming latexes that cure at ambient temperature, forming flexible, water-resistant, flame-retardant deposits. Comparable results are obtained, for equivalent weight percentages of the deposited latex solids, by either pre-coating the portion of paper wrapper that encloses the charge of tobacco or smoking medium or by post-treatment of the external surface of the assembled cigarette. For cigarettes having paper wrappers coated to contain 19.+-.6 weight percent latex solids of this invention, based on the weight of the treated paper that encloses the smoking medium, after being lit and left unattended a self-extinguishing time of from 1 to 3 minutes can be expected, meeting a practicable compromise for the smoker between safety and smoking convenience.
A smoking article includes at least one strip of heat conducting material extending from one end of the tobacco rod of a smoking article to the opposite end of the tobacco rod. Preferably, the strip of material is at the interface between the tobacco rod and the cigarette paper and extends substantially from the lighting end of the tobacco column to at or near the attachment of a filter to the tobacco column.
A method and system for capturing and analyzing an image of a moving web of cigarette paper having a plurality of transverse banded regions. The captured images of the moving web of cigarette paper are analyzed to determine various characteristics of a population of cigarettes made with the cigarette paper. Each captured image is decomposed into a matrix of grey scale values associated with individual pixels of the image. The values are further processed to determine a width of a banded region on the cigarette paper. The average widths of banded regions, as well as the standard deviation of widths may be analyzed and correlated to freeburn and ignition propensity characteristics of a population of cigarettes formed from the measured cigarette paper.
The invention is an improved specially designed wrapper construction for smoking articles producing controlled burn properties of smoking articles such as cigarettes so that the cigarette will self-extinguish after free burning in air for a designed time period. In addition, the wrapper construction results in cigarettes with reduced tendency to ignite combustible substrates, such as upholstered furniture, when in contact with them. Therefore, smoking articles with this wrapper construction reduce the likelihood of accidental fires, yet they free-burn rapidly for a designed period of time without puffing. However, during a normal puffing sequence the behavior of cigarettes with these wrappers is indistinguishable from commercial cigarettes. On the other hand, other self-extinguishing cigarettes go out without puffing and therefore have to be relighted frequently. The wrapper constructions of the present invention include single or double wraps of cigarette paper which are inherently incapable without elevated levels of burn promoting chemical or supporting cigarette free burn. The construction is modified by application of a plurality of zones of elevated levels of burn promoter to the extent that the cigarette burns normally in the treated zones. Thus, when the burning coal advances to an area of untreated wrap, it reliably self-extinguishes unless puffed. The extent of the treated zones controls the time required for the cigarette to self-extinguish. Required wrappers are preferably those having a Burn Mode Index ("BMI") as defined in the range of from about 1.5 cm.sup.-1 to about 6.0 cm.sup.-1 for the single wrap embodiment and, for the double wrap embodiment, about 0.1 cm.sup.-1 to about 4.0 cm.sup.-1 for the inner wrap and about 2 cm.sup.-1 to about 40 cm.sup.-1 for the outer wrap depending on the BMI of the inner wrap. The wrappers and smoking articles of the invention may be produced using conventional methods and equipment.
The invention describes a smoking article (1) comprising a wrapper (3) enwrapping a tobacco smoking material (2), the wrapper comprising a ceramic material and being capable of mechanically trapping mainly aqueous particulate phase materials in the sidestream smoke, thereby reducing sidestream smoke deliveries considerably despite the use of the wrapper with conventional tobacco materials.
