Tobacco – Cigar or cigarette making – Tobacco feeding
Reexamination Certificate
1999-10-19
2001-10-23
Derrington, James (Department: 1731)
Tobacco
Cigar or cigarette making
Tobacco feeding
C131S280000, C131S360000, C131S362000, C162S181100, C162S181200, C162S181400
Reexamination Certificate
active
06305382
ABSTRACT:
FIELD OF THE INVENTION
The present invention is generally directed to reduced basis weight wrapping papers for use in smoking articles and to a method of producing the wrapping papers. More particularly, the present invention is directed to a wrapping paper that contains white pigments and optionally black pigments possessing a sufficient particle size that effectively both scatter and absorb light for maintaining an opacity and tensile strength within commercially acceptable ranges, while decreasing the basis weight of the wrapping papers.
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 fiber 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, 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 the characteristics of the ash that is formed as the cigarette burns. Cigarette paper can even be used to limit the amount of smoke that emanates from the lit end of a cigarette when it is left burning and to reduce the tendency of a cigarette to ignite adjacent surfaces.
In the past, wrapping paper opacity was determined primarily as a function of the amount of filler incorporated into the papers. In general, opacity levels are increased as the amount of filler added to the paper is increased. Unfortunately, however, increasing filler levels to increase opacity can adversely affect other characteristics of the paper. For example, increasing filler levels can decrease the strength of the paper. Altering filler levels can also affect the permeability of the paper which may in turn affect the burn properties of the paper. As such, there is increasing pressure within the industry to keep filler levels in cigarette paper within preset ranges, severely restricting viable methods for increasing paper opacity.
Currently, focus has also been placed upon decreasing the basis weight of wrapping papers in order to decrease the amount of material needed to produce the papers. By reducing the basis weight of wrapping papers, however, two problems can result. First, by reducing the basis weight, the opacity of the wrapping paper is simultaneously decreased causing the paper to aesthetically decline in appearance by unmasking the cigarette's contents. Decreasing the basis weight of the wrapping papers also can cause a decrease in the tensile strength of the paper.
Due to the above limitations, it has been extremely difficult to create a wrapping paper with a decreased basis weight while maintaining an opacity and tensile strength level that is commercially acceptable.
Thus, a need exists for a wrapping paper for smoking articles that has a decreased basis weight while at the same time maintaining an opacity of at least 70% and a tensile strength above minimum commercial requirements. Also, a need exists for a method of producing such wrappers. A need also exists for a method of reducing basis weight without adversely interfering with other physical properties of the paper.
SUMMARY OF THE INVENTION
The present invention recognizes and addresses the foregoing disadvantages, and others of prior art constructions and methods.
In general, the present invention is directed to reduced basis weight wrapping papers for use in smoking articles that retain the opacity and tensile strength levels commercially required. According to the present invention, the reduced basis weight wrapping papers contain a white pigment and optionally a black pigment.
Accordingly, it is an object of the present invention to provide a reduced basis weight paper that can be used as an outer wrapper for smoking articles.
Another object of the present invention is to provide a wrapping paper for smoking articles having a reduced basis weight and maintaining an opacity of at least 70%.
It is another object of the present invention is to provide a wrapping paper for smoking articles having a reduced basis weight while maintaining a tensile strength above the minimum required for conventional wrapping paper.
Still another object of the present invention is to provide a method for producing reduced basis weight cigarette wrapping papers.
Yet another object of the present invention is to provide a wrapping paper for smoking articles having a reduced basis weight that contains a white pigment having a particle size that is roughly equal to one-half the wavelength of visible light, and optionally a small amount of a black pigment.
These and other objects of the present invention are achieved by providing a wrapping paper for a smoking article. The wrapping paper includes a paper substrate containing at least a first filler. The first filler comprises a white pigment having a median particle size of from about 0.1 microns to about 0.5 microns, and more particularly from about 0.2 microns to about 0.4 microns. Within this particle size range, the white pigment possesses more efficient light scattering characteristics than those used in the past.
Optionally, a second filler can be incorporated in to the paper wrapper. The second filler comprises a black pigment which can be present within the paper substrate in an amount up to about 2% by weight and particularly from about 0.1% to about 1.0% by weight.
The white pigment can be, for instance, precipitated calcium carbonate (PCC), titanium dioxide, or mixtures thereof, while the black pigment can be carbon, iron oxide, or mixtures thereof. The total filler content within the paper substrate can be from about 15% to about 40% by weight, and particularly from about 20% to about 30% by weight.
Conventional wrapping paper has a typical basis weight of about 25 g/m
2
to 26 g/m
2
. The wrapping paper made in accordance with the present invention can have a basis weight from about 14 g/m
2
to about 22 g/m
2
, and in particular from about 17 g/m
2
to about 20 g/m
2
. The permeability of wrapping papers made in accordance with the present invention can be from about 5 Coresta units to about 80 Coresta units, and in particular from about 15 Coresta units to about 55 Coresta units.
Through the use of the fillers described above, paper wrappers can be made having a reduced basis weight while maintaining an acceptable opacity and tensile strength. In particular, the fillers are incorporated into the paper in a manner so as to maintain the opacity of the paper in amount of at least 70%. The tensile strength of the paper, on the other hand, should be at least 1800 g/29 mm, and particularly at least 2000 g/29 mm.
The present invention is also directed to smoking articles containing a column of smokable filler. The column of smokable filler is surrounded by a reduced basis weight wrapping paper as described above.
Other objects, features and aspects of the present invention are discussed in greater detail below.
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Derrington James
Dority & Manning P.A.
Lopez Carlos
Schweitzer-Mauduit International, Inc.
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