WO2003005840A1

WO2003005840A1 - Self-extinguishing paper wrappers and smoking articles

Info

Publication number: WO2003005840A1
Application number: PCT/IB2002/004143
Authority: WO
Inventors: Stuart Nixon
Original assignee: Robert Fletcher (Greenfield) Limited
Priority date: 2001-07-10
Filing date: 2002-07-10
Publication date: 2003-01-23

Abstract

Smoking articles having a significantly reduced ignition proclivity, including cigarettes, cigars and little cigars are provided. The present invention relates to a paper wraper suitable for use in a smking article wherein the paper wrapper is coated over at least part of its surface area with a substance. The substance is comprised of two or more of the following: alumino silicates including sodium alumino silicate and/or magnesium alumino silicate, anhydrous sodium carbonate, sodium carbonate decahydrate, silicon dioxide, calcium carbonate, di-sodium phosphate, mono-ammonium phosphate. Also provided are improved wrapper papers for smoking articles wherein the smoking articles self-extinguish. Methods of making the smoking articles and the paper wrapper composition are also described.

Description

Self-extinguishing Paper Wrappers and Smoking Articles

The present invention relates to a smoking articles having a significantly reduced ignition proclivity, including cigarettes, cigars and little cigars. The invention also relates to an improved wrapper paper for smoking articles wherein the smoking articles self-extinguish. The invention also relates to methods of making the smoking article and the paper wrapper composition.

There is an ongoing concern in the industry to produce cigarettes having wrappers which reduce the ignition proclivity of the smoking article. Recently, the state of New York enacted legislation requiring all cigarettes sold in the state to be "self-extinguishing."

Two main obstacles to achieving a commercially successful self- extinguishing smoking article are flavor and the delivery of smoke constituents. A smoking article can be made to self extinguish but it will not achieve widespread acceptance of its flavor if the flavor is noticeably different from the consumer's original brand. Additionally, in order for the self-extinguishing brand to be considered as an acceptable alternative to the consumer, deliveries of the self extinguishing smoking article must be similar or the same as the consumer's original brand. Many attempts have been made to design a commercially successful smoking article having a reduced free burn time, but no such attempts resulted in a cigarette which was acceptable to the consumer.

For example, in U.S. Patent No. 4,044,778, the wrapper of the cigarette is provided with a silicon dioxide coating that causes the cigarette to self-extinguish in response to heat of the burning cigarette. This is achieved by a slow burning rate of the wrapper and limited air access to the burning coal as a result of the density of the ash surrounding it. However, the cigarette was unsuitable for commercial purposes due to swelling which caused the cigarette to raise from contact with the surface upon which it rested. Further, silicon dioxide coatings are easily visible and thus unappealing to the consumer.

In U.S. Patent No. 4,739,775 a paper material is treated in a manner suitable for forming periodically spaced strips having different characteristics than the base web to be modified. Mineral fillers such as precipitated calcium carbonate, ground limestone, sodium silico aluminate, amorphous silica, and calcium silicate can be added for purposes of enhancing the overall appearance of the paper. However, the wrappers are formed by adhesion of the treated paper to the base paper by a process that is difficult and costly for use in mass production.

In U.S. Patent No. 5,878,753, discrete bands of reduced permeability were added to the paper on the wire. Ignition proclivity was achieved by reducing the porosity of the cigarette paper in the area of the bands, thus causing "speed bumps" which resulted in a restriction of oxygen flow to the coal. However, this method was limited in that once the paper becomes non-porous it cannot be made even more less porous. Thus, the only method of decreasing ignition proclivity would be to increase the width of the bands. Increasing the band width gave rise to significant problems of tar/nicotine deliveries and causes an unpleasant taste. Additionally, this method is not readily adaptable for various different brands of cigarettes or various burn promoters.

Other efforts to produce smoking articles with altered burn rates are described in U.S. Patent No. 5,417,228; U.S. Patent No. 4,489,650; U.S. Patent No. 4,452,259; U.S. Patent No. 2,013,508; U.S. Patent No. 4,077,414; and U.S. Patent No. 5,878,754. Thus what is needed is a wrapper paper that is self-extinguishing and suitable for rapid mass production but can still accommodate the qualities of individual brands of smoking articles such that the attractive properties of flavor and delivery are preserved for the consumer.

Summary of the Invention

The present invention relates to a paper wrapper suitable for use in a smoking article wherein the paper wrapper is coated over at least part of its surface area with a substance. The substance is comprised of two or more of the following: alumino silicates including sodium alumino silicate and/or magnesium alumino silicate, anhydrous sodium carbonate, sodium carbonate monohydrate, sodium carbonate heptahydrate, sodium carbonate decahydrate, silicon dioxide, calcium carbonate, di-sodium phosphate, mono-ammonium phosphate and a suitable matrix or water. The matrix may be carboxymethyl cellulose, starch, guar gum, poly(vinyl alcohol) or any combination thereof. In one embodiment, the matrix comprises up to 10% carboxymethyl cellulose by weight of the substance applied to the wrapper paper. In embodiments in which the substance comprises sodium carbonate, the total concentration of sodium carbonate in the substance is between 2 to 70% by weight.

In embodiments in which the substance comprises silicon dioxide, the total concentration of silicon dioxide in the substance is between 2 to 30% by weight. The coating of the substance in the present invention is preferably over at least 5% and can be over up to 50% of the surface area of the paper wrapper.

Also included in the present invention is a method of treating the paper of smoking articles in order to cause the smoking article to extinguish if it is not puffed. The method comprises the step of coating or printing at least part of the surface area of the paper with a mixture. The mixture includes two or more of the following: alumino silicates, including sodium alumino silicate and/or magnesium alumino silicate, anhydrous sodium carbonate, sodium carbonate monohydrate, sodium carbonate heptahydrate, sodium carbonate decahydrate, silicon dioxide, calcium carbonate, di-sodium phosphate, mono-ammonium phosphate and a suitable matrix or water. The inventive method is readily adaptable to various brands of smoking articles in order to maintain important characteristics such as flavor or delivery of a particular brand.

Another aspect of the present invention is a self-extinguishing smoking article suitable for mass commercial production. The smoking article comprises the paper wrapper of the present invention.

Detailed Description of the Invention

The present invention is directed to wrapping paper of a self-extinguishing smoking article having a coating or printed area that can be varied to control ignition proclivity, and that is suitable for mass production. Further, the inventive paper and method of making the paper is readily adaptable to existing brands without significantly altering characteristics of the brand(s) such as flavor and delivery of smoke constituents. For these reasons, the present invention is a significant advancement over prior attempts to produce a marketable self-extinguishing smoking article.

The term, "smoking article" includes but is not limited to items such as cigarettes and cigars of all sizes. While the present invention is particularly suitable to cigarettes, any manner of smoking article is within the scope and spirit of the present invention.

As used herein, "ignition proclivity" is a measure of the tendency of the smoking article or cigarette to ignite a flammable substrate if the burning cigarette is dropped or otherwise left on a flammable substrate. A test for ignition proclivity of a cigarette has been established by NIST (National Institute of Standards and Technology) and comprises placing a smoldering cigarette on a flammable test fabric and recording the tendency of the cigarette to either ignite the test fabric, burn the test fabric beyond a normal char line of the fabric, burn its entire length without igniting the fabric, or self-extinguish before igniting the test fabric or burning its entire length. Also for purposes of the present invention, whether a smoking article is self-extinguishing is measured by lighting the smoking article and holding it horizontally. If the smoking article self-extinguishes, it is recorded as "pass." If the smoking article does not self-extinguish, a "fail" is recorded. Visibility of the coating is determined by human visual inspection.

For purposes of the present invention, the "free burning rate" is measured by dividing the burning time in minutes into the length of the tobacco rod consumed (in millimeters) during burning. In a typical conventional untreated cigarette, the cigarette burns its full length. The cigarettes in accordance with the present invention self-extinguish during free burning.

The coating or printed area of the paper wrapper should be over at least about 5% and up to about 50% of the surface area of the paper wrapper. In some embodiments, the coated area is between 5-25%, 5-15%, 10-15% or 5-10% of the surface area of the paper wrapper. In other embodiments, the coating is between 25- 50%, 25-40%, 30-50%, 40-50% or 25-35% of the surface area of the paper wrapper. The coating can be in the form of discrete bands or other discrete patterns. Alternatively, the coating can be distributed over non-discrete areas of the paper. The paper wrapper of the present invention can be used for cigarettes of any length or circumference and having different fillers such as tobacco, expanded tobacco, a variety of tobacco blend types, reconstituted tobacco materials, non- tobacco filler materials and combinations thereof. The smoking articles with which the paper wrapper may be used can be of any length or circumference. In embodiments in which the smoking article is a cigarette, preferably, the circumference of the cigarette is in the range of about 15 millimeters to about 28 millimeters.

Acceptable base paper for the present invention includes any form of cigarette paper, RYO cigarette paper or other paper suitable for smoking articles. In one embodiment, the paper is IVMC45-Robert Fletcher Specification 3054X.

Percentages, ranges and exact ratios required on the final cigarette would be known to those skilled in the art of cigarette manufacture and or cigarette paper manufacture and would be dependent upon presence of other substances in the tobacco rod such as burn promoters. In principle, the self-extinguishing additives should be at the minimum concentration consistent with maintaining their ability to self-extinguish in order to maintain optimal taste of the smoking article. However, additives in the smoking article such as burn promoters can necessitate higher concentrations of the inventive substance in the paper wrapper. In particular, the substance can be up to 30% of the total coat weight. In one embodiment, the substance is between 1-20% of total coat weight. In another embodiment, the substance is between 1-15% of the total coat weight. In yet another embodiment, the substance is between 1-10%) of the total coat weight.

The substance applied to the paper wrapper is comprised of two or more of the following: alumino silicates, including sodium alumino silicate and/or magnesium alumino silicate, anhydrous sodium carbonate, sodium carbonate monohydrate, sodium carbonate heptahydrate, sodium carbonate decahydrate, silicon dioxide, calcium carbonate, di-sodium phosphate, and mono-ammonium phosphate. In some embodiments, a synthetic magnesium alumino silicate such as Hydrex® (Huber Engineered Materials, Hamina, Finland) may be included. Additionally, a suitable matrix or water can be present. The addition of a matrix or binder allows for a greater range of application techniques to be employed, including conventional paper coating or printing techniques. Acceptable binders or fillers in the present invention include but are not limited to, carboxymethyl cellulose (CMC), hydroxypropyl cellulose, guar gum, starch, alginate, pectin, polyvinyl alcohol or various other polysaccharide binders or the like. Virtually any substance which is film forming and/or viscosity modifying would be suitable for use as a matrix in the present invention. In one preferred embodiment, the matrix is CMC, starch, or a combination of CMC and starch. In one embodiment, the matrix comprises up to 10% carboxymethyl cellulose by weight of the substance applied to the wrapper paper.

In embodiments in which the mixture comprises sodium carbonate, the total concentration of sodium carbonate in the substance should be between 2 to 70%o by weight. Preferably, the total concentration of sodium carbonate in the substance is between 10-20% by weight, more preferably between 15-20% by weight, still more preferably between 18-20%> by weight and yet still more preferably 20%) by weight. In embodiments in which the substance comprises silicon dioxide, the total concentration of silicon dioxide in the substance is ideally between 2 to 30% by weight. Preferably, the total concentration of silicon dioxide in the substance is between 2-15% by weight. Even more preferably, the concentration of silicon dioxide is between 3-10%o, still more preferably between 3-8%>, and yet still more preferably between about 3-6%> by weight. In one embodiment, the concentration of silicon dioxide in the substance is 3%. In another embodiment, the concentration of silicon dioxide in the substance is 6%.

Ingredients of the mixture are mixed using commonly known techniques such as combining the ingredients together in a suitable vessel and mixing together using conventional methods well known in the art. For embodiments comprising silicon, the silicon is deposited in the form of SiO2, or as a component of sodium silicate, also referred to as "waterglass."

Acceptable viscosities in the present invention include any viscosity suitable for gravure printing. In preferred embodiments, the viscosity should be between about 12-30 seconds using a Seta Zahn viscosity cup number 2, with a range of 19 to 156 cSt, which allows simple measurement of viscosity by measuring the time taken for a known amount of fluid to drain through the cup, a conversion table then coverts the measured time to a viscosity value expressed in centiStokes. In one preferred embodiment, viscosity as measured in the cup is about 18 seconds. Also included in the present invention are methods of making a self- extinguishing paper wrapper which are adaptable for use in different brands of smoking articles. One method comprises the step of coating or printing at least part of the surface area of the paper with the inventive substance or mixture described above. A particularly desirable feature of the present invention is that the mixture can be applied to the wrapping paper in relatively high speed commercial printing or coating processes, such as gravure or flexigraphic coating, or by a painting mechanism. The mixture may be applied to the paper in a single pass or multiple passes to achieve the desired result.

"Gravure printing" refers to a process of printing in which an image carrier is a copper plate or copper-plated cylinder, which has been etched or engraved with microscopic cells. The cylinder or plate is flooded with a very fluid ink/solution and the excess ink/solution is doctored off. The ink/solution in the cells is then transferred onto the paper in the printing nip formed with a rubber-covered impression roll.

A gravure cylinder is engraved using techniques well understood in the art. For example, any number of discrete patterns can be engraved onto the cylinder, resulting in the printing of the mixture onto a roll of paper sufficiently wide to allow subsequent slitting via a precision slitting technique well understood by persons skilled in the art of cigarette paper conversion into any number of bobbins of paper of widths and lengths suitable for use on a standard or proprietary cigarette making machine, e.g., 27mm wide by 6000m in length. The resulting bobbins are made into cigarettes. In preferred embodiments, the substance of the present invention is applied to the inside of the paper wrapper to minimize the optical effect on the outside of the paper.

Another desirable aspect of the invention is adaptability to a wide variety of brands of smoking articles. Unlike self-extinguishing smoldng articles attempted in the past in which the cigarettes must be designed around the paper (restricting burn promoters in the tobacco rod, for example), the present invention is not limited to a particular level or composition of coating or printed area. Thus, the invention is directed to a paper that designs itself around the smoking article and permits a substantial scope in alteration of the key parameters of the cigarette. This flexibility allows a self extinguishing paper to be "retro-fitted" to an existing brand without significantly altering characteristics of the taste, size, shape or tobacco content. The resulting smoking article will self extinguish yet maintain widespread acceptance of flavor and/or deliveries which are compatible to the consumer's original brand.

Publications and references, including but not limited to patents and patent applications, cited in this specification are herein incorporated by reference in their entirety in the entire portion cited as if each individual publication or reference were specifically and individually indicated to be incorporated by reference herein as being fully set forth. Any patent application to which this application claims priority is also incorporated by reference herein in the manner described above for publications and references. The following examples further illustrate the present invention, but of course, should not be construed as in any way limiting its scope.

Example 1.

Experimental work was carried out by printing 1.5mm bands of SiO₂ onto rectangular paper 5 cm by 10 cm in dimension. The printing was performed using a standard draw-down bar as is used throughout the printing industry, or by a screen printing technique or by 'painting' the paper with the substance. The paper was dried, then lit and allowed to smoulder. The SiO₂ bands successfully extinguished the burn line. However, the bands were easily visible and penetrated the paper. Various techniques were employed to reduce visibility of the bands, including dilution and addition of chalk, which were unsuccessful and/or unsuitable for commercial purposes.

Example 2. Sodium carbonate was analyzed for ability to self-extinguish paper in a smoking article. A water based solution containing 30%> dissolved solids of sodium carbonate was applied using the same or similar techniques as described in Example 1 above on 1.5 mm bands onto rectangular paper 5 cm by 10 cm in dimension. The sodium carbonate was found to successfully extinguish the burn line when the paper was allowed to smoulder. These bands were significantly less visible than that of SiO₂, but still too visible to be used for wide scale commercial purposes. Bands having lower concentrations of sodium carbonate (less than 10%) were less visible, but failed to reliably extinguish the burn line of the paper. Addition of carboxymethyl cellulose to the sodium carbonate solution resulted in decreased visibility of the bands. Further, it was found that less retardant was necessary to extinguish a burn line if the paper was rolled in the form of a cigarette as opposed to being flat.

Example 3.

Detailed analysis using NaCO₃, CMC and SiO was conducted. Solutions of differing concentrations were examined to determine a solution that complies with the characteristics of a gravure printing, and extinguishes the burn line while maintaining low to zero visibility. These results are described below in Table 1.

As can be seen from Table 1, a solution containing sodium carbonate is more effective at high concentrations, which are too visible for commercial use and fails to extinguish a burn line. Solutions containing only CMC are too viscous and are thus unsuitable for use in mass production. Solutions containing only silicon dioxide were also too visible for commercial use. However, mixtures containing a combination of sodium carbonate and silicon dioxide or of CMC in combination with sodium carbonate and/or silicon dioxide (see Table 1) successfully extinguish the burn line of the paper while maintaining acceptable viscosity and visibility limits. For example, mixtures having 20% sodium carbonate with small amounts of silicon dioxide (2 to 9%) are successful fire retardants but do not "spoil" the paper as was the case in higher concentrations of sodium carbonate alone. Average pick up was calculated to be approximately 1.3 gm^"2 for a total overall solution concentration of approximately 23% in water. Pick up can be defined as the increase in mass over a set area when a coating is applied to the paper, i.e., in the coated areas of a particular embodiment, the average pick up was calculated as 1.3 grams per square meter. That is, the weight per square meter of the coated area is 1.3 grams heavier than the weight per square meter of the uncoated area. Pick up is readily altered by changing the conditions or methods used to apply the coating. While this invention has been described with an emphasis upon preferred embodiments, it will be obvious to those of ordinary skill in the art that variations in the preferred devices and methods may be used and that it is intended that the invention may be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications encompassed within the spirit and scope of the invention as defined by the claims that follow.

Claims

What is claimed:

1. A smoking article comprising a paper wrapper, wherein the paper wrapper is coated over at least part of its surface area with a substance comprising two or more of anhydrous sodium carbonate, sodium carbonate monohydrate, sodium carbonate heptahydrate, sodium carbonate decahydrate, silicon dioxide, calcium carbonate, di-sodium phosphate, and mono-ammonium phosphate.

2. The smoking article of claim 1 wherein the substance additionally comprises a matrix.

3. The smoking article of claim 2 wherein the matrix comprises carboxymethyl cellulose, starch, guar gum, polyvinyl alcohol or a combination thereof .

4. The smoking article of claim 3 wherein the suitable matrix comprises up to 10% carboxymethyl cellulose by weight.

5. The smoking article of claim 1 wherein the total concentration of sodium carbonate in the substance is between 2 to 70%> by weight and silicon dioxide in the substance is between 2 to 30%> by weight.

6. The smoking article of claim 1 wherein the total concentration of sodium carbonate in the substance is between 10-20%) by weight and the total concentration of silicon dioxide in the substance is between 3-6% by weight.

7. The smoking article of claim 6 wherein the total concentration of sodium carbonate in the substance is 20%) and the total concentration of silicon dioxide in the substance is 3%>.

8. The smoking article of claim 6 wherein the total concentration of sodium carbonate in the substance is 20%> and the total concentration of silicon dioxide in the substance is 6%.

9. The smoking article of claim 1, wherein said coating is over at least 5%> of the surface area of the paper wrapper.

10. The smoking article of claim 9 wherein said coating is over up to 50% of the surface area of the paper wrapper.

11. The smoking article of claim 1, wherein the coating causes the smoking article to extinguish if it is not puffed.

12. A method of treating the paper of smoking articles in order to cause the smoking article to extinguish if it is not puffed comprising the step of coating at least part of the surface area of the paper with a mixture comprising two or more of anhydrous sodium carbonate, sodium carbonate monohydrate, sodium carbonate heptahydrate, sodium carbonate decahydrate, silicon dioxide, calcium carbonate, di- sodium phosphate, mono-ammonium phosphate in combination with a matrix or water.

13. The method of claim 12 wherein the matrix comprises carboxymethyl cellulose, starch, guar gum, polyvinyl alcohol or a combination thereof.

14. The method of claim 12 wherein the matrix comprises up to 10%o carboxymethyl cellulose by weight.

15. The method of claim 12 wherein the concentration of sodium carbonate in the mixture is between 5 to 30%> by weight and the concentration of silicon dioxide in the mixture is between 0.5 to 9%> by weight.

16. The method of claim 15 wherein the total concentration of sodium carbonate in the mixture is between 10-20% by weight and the total concentration of silicon dioxide in the mixture is between 3-6%> by weight.

17. The method of claim 16 wherein the total concentration of sodium carbonate in the mixture is 20% and the total concentration of silicon dioxide in the mixture is 3%>.

18. The method of claim 16 wherein the total concentration of sodium carbonate in the mixture is 20% and the total concentration of silicon dioxide in the mixture is 6%> .

19. The method of claim 12 wherein said coating is over at least 5% of the surface area of the paper wrapper.

20. The method of claim 19 wherein said coating is over up to 50% of the surface area of the paper wrapper.

21. A paper wrapper suitable for use in a smoking article, said paper wrapper having a coating over at least part of its surface area with a mixture comprising two or more of anhydrous sodium carbonate, sodium carbonate monohydrate, sodium carbonate heptahydrate, sodium carbonate decahydrate, silicon dioxide, calcium carbonate, di-sodium phosphate, and mono-ammonium phosphate.

22. The paper wrapper of claim 21 wherein the substance additionally comprises a matrix.

23. The paper wrapper of claim 22 wherein the matrix comprises carboxymethyl cellulose, starch or a combination thereof.

24. The paper wrapper of claim 23 wherein the matrix comprises carboxymethyl cellulose in a concentration between 5-10%) by weight.

25. The paper wrapper of claim 21 wherein sodium carbonate is present in the mixture in the range of 2 to 70%> by weight and silicon dioxide is present in the mixture in the range of 2 to 30%> by weight.

26. The paper wrapper of claim 25 wherein the total concentration of sodium carbonate in the mixture is between 10-20% by weight and the total concentration of silicon dioxide in the mixture is between 3-6%> by weight.

27. The paper wrapper of claim 26 wherein the total concentration of sodium carbonate in the mixture is 20%> and the total concentration of silicon dioxide in the mixture is 3%.

28. The paper wrapper of claim 26 wherein the total concentration of sodium carbonate in the mixture is 20%> and the total concentration of silicon dioxide in the mixture is 6%.

29. The paper wrapper of claim 22 wherein said coating is over at least 5%> of the surface area of the paper wrapper.

30. The paper wrapper of claim 29 wherein said coating is over up to 50%> of the surface area of the paper wrapper.