Tobacco – Tobacco or tobacco substitute product or component part thereof – Cigar or cigarette
Reexamination Certificate
2001-11-13
2003-07-01
Griffin, Steven P. (Department: 1731)
Tobacco
Tobacco or tobacco substitute product or component part thereof
Cigar or cigarette
C131S331000, C131S360000, C162S139000, C162S138000, C162S146000, C162S145000
Reexamination Certificate
active
06584981
ABSTRACT:
FIELD OF THE INVENTION
The present invention is generally directed to a method for improving the ash characteristics of a paper used to construct smoking articles. More particularly, the present invention is directed to a process for improving the ash cohesiveness of cigarette paper by incorporating carbon fibers into the paper sheet.
BACKGROUND OF THE INVENTION
Smoking articles such as cigarettes are conventionally made by wrapping a column of tobacco in a white wrapping paper. At one end, the smoking article usually includes a filter through which the article is smoked. Filters are attached to smoking articles using a tipping paper which is glued to the white wrapping paper. The wrapping papers and tipping papers used to construct smoking articles are typically made from flax or other cellulosic fibers and contain a filler, such as calcium carbonate.
Besides being used to hold the cigarette together, cigarette wrapping papers and tipping papers also contribute to and control many physical properties and characteristics of the cigarette. For instance, cigarette wrapping paper affects the rate at which the cigarette burns, i.e. the number of puffs per cigarette and the total tar delivery per puff. Another property of the cigarette that is affected by the wrapper is the appearance and cohesiveness of the ash that is formed as the cigarette burns. Ideally, cigarette ash should be cohesive, should not flake off from the cigarette, and should have an aesthetically pleasing appearance.
The quality of cigarette ash is generally determined by rating the ash according to four criteria. The first criterion is ash color. In general, a whiter ash has a more aesthetic appearance and is thus more desirable. The second criterion is ash cohesiveness and the ability of the ash to avoid excessive flaking. The ash should not flake off the cigarette unless the cigarette is flicked or tapped on an object. Further, once the cigarette is tapped, the ash should break off in clumps and not disintegrate.
The last two criteria used to evaluate cigarette ash are dependant for the most part upon the cigarette wrapping paper and not upon the ash characteristics of the tobacco column. For example, the third criterion for evaluating cigarette ash is the thickness of the char line appearing on the wrapper as a cigarette is burned. Thinner char lines are preferred. Finally, the last criterion is the extent to which the cigarette wrapper stains downstream (towards the filter) from the ash as the cigarette is smoked. A high quality wrapping paper will not stain or discolor throughout the length of the cigarette as the cigarette is puffed.
In the past, various methods have been devised in order to improve the ash characteristics of a smoking article. For instance, previous efforts for improving the appearance of ash have included changing the type of cellulosic fiber used to make the cigarette wrapping paper. Also, ash modifiers have been added to the paper or to the tobacco. In particular, it has been proposed in the past to add to the paper starches or salts to improve ash characteristics without adversely affecting the qualities of the paper. Unfortunately, the use of conventional cellulosic fibers and ash modifiers does not provide sufficient ash cohesiveness such that the ash does not flake off too easily.
Thus, a need exists for a method of improving cigarette ash characteristics without detrimentally affecting the other properties of the cigarette. In particular, a need exists for a method that improves the ash cohesiveness of a cigarette wrapping paper without adversely affecting the appearance of the ash or the permeability of the paper, the taste, the burn rate, the puff count, or the tar delivery per puff of a cigarette incorporating the paper.
SUMMARY OF THE INVENTION
The present invention recognizes and addresses various disadvantages of prior art constructions and methods. Accordingly, it is an object of the present invention to provide a method for improving the ash characteristics of a cigarette paper and of a cigarette incorporating the paper.
It is another object of the present invention to provide a method for improving the ash cohesiveness of a cigarette paper without adversely affecting other cigarette ash characteristics.
Still another object of the present invention is to provide a method for improving the ash cohesiveness of a cigarette paper by incorporating into the paper carbon fibers.
Another object of the present invention is to provide a method for improving the ash cohesiveness of a cigarette paper by incorporating into the paper carbon fibers having an average length less than about 0.75 inches.
It is another object of the present invention is to provide a method for improving the ash cohesiveness of a cigarette paper by incorporating into the paper carbon fibers having an average length less about 0.75 inches and added in an amount less than about 60% by weight.
These and other objects of the present invention are achieved by providing a process for improving the ash characteristics of a paper wrapper for a smoking article. The process includes the step of incorporating carbon fibers into a paper wrapper. The carbon fibers have an average length less than about 0.75 inches, particularly from about 0.125 inches to about 0.5 inches, and more particularly about 0.25 inches. The carbon fibers can be added to the, paper wrapper in an amount from less than about 60% by weight, and more particularly from about 5% to about 20% by weight.
According to the present invention, the paper wrapper can have a basis weight from about 18 gsm to about 60 gsm, but typically is from about 45 gsm to about to 55 gsm in one embodiment and from about 22 gsm to about 32 gsm in an alternative embodiment. The paper wrapper can have a permeability of from about 5 Coresta units to about 2000 Coresta units, particularly from about 5 Coresta units to about 80 Coresta units.
In one embodiment, a filler can be coated onto the paper wrapper or incorporated into the paper wrapper. The filler, for instance, can be a calcium carbonate. For example, calcium carbonate filler can be added in an amount of from about 20% by weight to about 40% by weight. The paper wrapper can also be coated with a burn control additive. The burn control additive, for instance, can be an alkali metal salt, an acetate, a phosphate salt, or mixtures thereof. For example, the burn control additive can be a citrate and can be added to the paper in an amount from about 0.3% to about 12% by weight.
In still another embodiment, a viscosity modifier can be incorporated into the paper. For instance, the viscosity modifier can be an alginate. This makes it easier to process the carbon fibers in the slurry. A better formation is obtained.
Other objects, features and aspects of the present invention are discussed in greater detail below.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only and is not intended as limiting the broader aspects of the present invention which broader aspects are embodied in the exemplary construction.
The present invention is generally directed to a method for improving the ash characteristics of a wrapping paper and for improving the ash characteristics of a smoking article incorporating the wrapping paper. Specifically, the characteristic of ash cohesiveness is improved by adding to the paper carbon fibers having an average length less than about 0.75 inches, and more particularly between about 0.125 inches to about 0.50 inches. The carbon fibers are generally added to the wrapping paper at an amount up to about 60% by weight, and more particularly between about 5% to about 20% by weight. Further, the ash cohesiveness of the paper is improved without significantly harming other ash characteristics or qualities of the wrapping paper.
Paper wrappers for smoking articles made in accordance with the present invention exhibit an ash that is significantly more cohesive than many prior art construction
Dority & Manning P.A.
Griffin Steven P.
Halpern M.
Schweitzer-Mauduit International, Inc.
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