EP0175684B1

EP0175684B1 - Treatment of cigarette paper

Info

Publication number: EP0175684B1
Application number: EP84901502A
Authority: EP
Inventors: Charles C. Cohn
Original assignee: Cohn Rose
Current assignee: COHN ROSE
Priority date: 1983-01-24
Filing date: 1984-03-14
Publication date: 1989-08-16
Also published as: AU2813184A; AU601091B2; JPS61501546A; EP0175684A1; WO1985004080A1; EP0175684A4; CA1211021A; AU2656888A

Abstract

One version of a fire resistant cigarette comprises a charge of tobacco in a low-porosity wrapper substantially free of burn accelarator. The sidestream smoke from this cigarette can be reduced by treating the wrapper with water or ethyl alcohol. Fire resistance is further improved by depositing a linear burn rate reducing substance on the paper from the group consisting of citric acid, magnesium citrate, magnesium acetate, tartaric acid, acetic acid, lactic acid, a sugar, non-fat milk and skim milk. Similar results are achieved with conventional medium to high porosity cigarette papers by treating them with a burn rate reducing substance from the same group. In the case of high porosity cigarette paper, if only a part of the surface area is treated, the porosity of the untreated areas controls tar, nicotine, and carbon monoxide delivery. Still further improvements in sidestream smoke reduction and fire resistance may be achieved by the use of an additional layer of high-porosity cigarette paper in the wrapper.

Description

Technical field

This invention relates to the treatment of cigarette paper for fire resistance and for reduction of sidestream smoke, i.e. smoke emitted when the cigarette is not being puffed actively.

Background of the invention

Existing treatments of cigarette paper and/or tobacco for fire resistance and sidestream smoke reduction are subject to one or more of the following problems. In some cases, the treatment results in a dark colored ash which is unacceptable to many smokers. In other cases, the treatment gives the cigarette an appearance which might be considered unacceptable by some smokers.
One object of this invention is to provide sidestream smoke reduction in a cigarette by a simple and inexpensive means and method which do not adversely affect the desirability of the cigarette to the smoker.
Another object of the invention is to provide a fire-resistant cigarette which is simple and inexpensive to manufacture, while avoiding the undesirable characteristics of prior fire-resistant cigarettes.
Another object of this invention is to impart both fire resistance and sidestream smoke reduction to a cigarette by a comparatively simple and inexpensive expedient, namely the use of a cigarette paper having special filler content and porosity characteristics, and optionally by the treatment of cigarette paper with specially chosen chemical substances. It is also an object of this invention to achieve fire resistance and/or sidestream smoke reduction while maintaining a light colored cigarette ash. Still another object of the invention is to achieve fire resistance and/or sidestream smoke reduction without impairing the external appearance of the cigarette. Still another object is to achieve fire resistance and/or sidestream smoke reduction without causing excessive particulates in the mainstream smoke, and without seriously affecting the draw characteristics of the cigarette. In general, it is an object of the invention to achieve fire resistance and/or sidestream smoke reduction in a cigarette which is likely to be acceptable in all respects to most cigarette smokers. Still another object of the invention is to reduce the nicotine and tar delivery of a cigarette.
It is also an object of the invention to achieve one or more of the foregoing objects by a process which is easily and inexpensively carried out, and which does not have the alkalinity of the silicate treatments described in my United States patents 3,030,963, 3,183,914, 3,220,418, 4,044,778, 4,146,040 and 4,187,862.
The cigarette in accordance with the invention, for fire resistance and the reduction of sidestream smoke, comprises a charge of tobacco in a cigarette paper wrapper having a Greiner porosity of about 50 or more seconds, the cigarette paper having a weight between about 10 and 35 grams per square meter. The cigarette paper is substantially free of burn accelerator other than filler, and has a low filler content in the range of approximately 15 to 22%. Cigarette paper meeting the above requirements has been used in the past for wrapping cigarette filters. However, it apparently has not been used as a consumable wrapper for cigarette tobacco. I have found that low-porosity cigarette paper meets all of the above-stated objectives of the invention except for reduction of particulates in the sidestream smoke. I have also found that further improvements in performance of low-porosity, low-filler content paper can be achieved by treatment of the paper in water, ethyl alcohol, or in a solution or suspension of one or more of a wide variety of linear burn rate-reducing substances, as will be discussed in detail below.
I have also found that a specific class of burn rate-reducing substances is capable of even better achieving all of the above-listed objectives of the invention when additionally used to treat cigarette paper according to the invention. This specific class of burn rate-reducing substances comprises lactic acid, citric acid, magnesium citrate, magnesium acetate, tartaric acid, acetic acid, non-fat milk, skim milk and sugars. If only part of the area of this cigarette paper is treated, fire resistance and/or sidestream smoke reduction can be achieved while producing substantially less particulate matter than would be present in the mainstream smoke from a cigarette with a wrapper treated over its entire area.
Further objects and advantages of the invention will be apparent from the following detailed description.

Detailed description

For the purpose of this description and the claims, the following definitions shall apply:

"Cigarette paper" is defined as a tissue paper made from a highly beaten flax pulp stock, the paper being substantially free of pin holes and substantially free of sizing.

"Linear burn rate-reducing substance" means any substance which, when applied to cigarette paper and dried, causes the cigarette paper to exhibit a lower static burn rate than the same paper in an untreated condition. Such substances include citric acid, magnesium citrate, magnesium acetate, diammonium phosphate, trisodium phosphate, alumina gel, sodium tetraborate, ammonium hydroxide, nickel acetate, potato starch, sugar, aluminum stearate, manganese sulfate, ammonium sulfate, ammonium sulfamate, aluminum sulfate, acetic acid, lacetic acid, and non-fat milk. Many other substances including sugars such as dextrose, maltose sucrose, etc. also qualify as linear burn rate-reducing substances. Burn rate-reducing substances have varying characteristics. All are applicable to low-porosity, low filler content cigarette paper. However, only a limited group of burn rate-reducers is applicable to conventional cigarette paper. The substances in this limited group which I have found produce good results are citric acid, magnesium citrate, magnesium acetate, tartaric acid, acetic acid, lactic acid, non-fat milks, skim milk, maltose, dextrose, sucrose, fructose and lactose.
"Filler" means calcium carbonate (CaC0₃) or any other substances used in the cigarette industry for the purpose of accelerating burning of paper. MgC0₃ and MgO are examples of other fillers which have been used.
"Greiner porosity" is a measure of cigarette paper porosity used throughout the cigarette industry. It refers to the time in seconds required for a specified volume of air to pass through a specified area of paper under a specified pressure. The higher the Greiner number, the lower the porosity of the paper.
"Sidestream smoke" is smoke emitted by a cigarette between puffs. This smoke does not pass through the tobacco rod or through the filter, and is considered particularly obnoxious by non-smokers. In testing for sidestream smoke, the cigarette is lit; puffed, held for one minute without puffing, and then puffed again. It is then placed under an inverted, widemouth glass jar three inches in diameter and seven inches tall. Sidestream smoke is evaluated by visually observing the quantity of smoke in the jar.
"Tar" refers to the liquid products of tobacco combustion, and is evaluated by observing the staining of the mouth end of a cigarette filter.
"Drying" refers to the removal of moisture or liquid substances by the application of heat, by the application of moving air, by simply permitting evaporation to take place under ambient conditions, or by any other suitable means. However, "drying" does not imply the removal of all moisture. Rather, in the context of the following description, "drying" refers to the removal of moisture after treatment of cigarette paper to an extent such that the cigarette paper has substantially the same moisture content that it had prior to treatment.
The "fire resistance test" referred to herein is a test described in the United States Federal Trade Commission's Standard for the Flammability of Mattresses and Mattress Pads (FF 4-72), (16 C.F.R. 1632). The Federal Trade Commission's test is intended for testing mattresses using conventional cigarettes. However, the test is equally applicable to the testing of cigarettes using standard mattresses, and a test on a standard mattress was used to determine the fire resistance of the cigarettes described in the examples herein. For the tests used to determine fire resistance of cigarettes made in accordance with the invention the mattress material used is a cotton ticking covering a cotton batting. The lit cigarette, after at least 30 seconds of free burn time in air, is placed horizontally over the mattress ticking, with uniform contact of the cigarette paper with the ticking. The cigarette is permitted to burn until it self-extinguishes before full consumption, in which case it is relit and retested. It may burn its full length and then self-extinguish. The cigarette is observed to determine whether or not it causes smoldering or ignition of the test mattress.
The tests used to determine fire resistance and other parameters reported un the examples herein were carried out on cigarettes made by factory-type machines or on cigarettes made by hand using careful controls to insure a uniform tobacco packing density similar to that of a factory-made cigarette.
Certain criteria pertaining to burning characteristics must be met by a cigarette in accordance with the invention. The cigarette must burn for at least one minute between puffs. The linear burn rate must be between about 1 and 6 mm/minute. Further, in the cuue of a cigarette in accordance with the invention having a treated conventional wrapper, the linear burn rate must be substantially slower than the burn rate of a corresponding cigarette which has an untreated wrapper but which is otherwise identical to the cigarette having the treated wrapper. For example if an untreated cigarette has a burn rate of 5 mm/minute, a corresponding cigarette with a water-treated wrapper should be treated sufficiently to have a burn rate substantially less than 5 mm/minute, e.g. 4 mm/minute.
Although treated cigarettes will generally exhibit sidestream smoke reduction at a burn rate of 6 mm/minute or less, and some of the same cigarettes will also exhibit fire resistance at a burn rate anywhere in the range of 1 to 6 mm/minutes, other cigarettes must be treated sufficiently to have a burn rate as low as 3.5 mm/minute in order to have satisfactory fire resistance.
An important phase of this invention pertains to the use of a low porosity cigarette wrapper having a relatively low filler content.
Whereas the wrappers of conventional cigarettes have a Greiner porosity in the range of about 10 to 40 seconds, and a filler content (usually calcium carbonate, magnesium carbonate or magnesium oxide) in the range of approximately 22 to 35% the cigarette in accordance with the invention use a wrapper having a Greiner porosity of about 50 or more seconds the filler content of the cigarette paper being in the range of approximately 15 to 22%. The weight of the cigarette paper is between about 10 and 35 grams per square meter as in the case of conventional cigarette paper. A typical paper having these characteristics is the so-called "plug wrap", which is used as a wrapper for cigarette filters, but has not been used as a wrapper for tobacco.
A cigarette having a wrapper consisting of such paper exhibits excellent fire resistance. When dropped on a test mattress, it may cause some charring, but does not start a smolder or fire, and eventually extinguishes itself.
In all of the examples herein, except as otherwise indicated, the cigarette tested was a "Winston-Lights" king size cigarette having an average circumference of approximately 25 mm.
In the following examples of cigarettes using low-porosity paper, the tested cigarettes were made from conventional cigarettes by removing the tobacco and wrapper from the filter plug, wrapping the low-porosity paper around the filter to form a tube, sealing the tube edges together, and carefully repacking the same tobacco in the tube to insure uniform tobacco density similar to that of the original cigarette. Where the paper was chemically trated, it was treated before replacement of the tobacco.
The following four examples pertain to "Winston-Lights" kingsize cigarettes comprising tobacco wrapped in low-porosity, low-filler content cigarette paper. In each example, the weight given refers to the weight of the paper, including the calcium carbonate filler, in grams per square meter. The porosity is the Greiner porosity in seconds.

Example 1

Weight=27 g./m^Z
CaC0₃=18.5%
Porosity=50 sec.

Example 2

Weight=₃₅ g./m²
CaC0₃=20.0%
Porosity=₅₀ sec.

Example 3

Weight=24 g./m²
CaCO₃=20%
Porosity=50 sec.

Example 4

Weight=24 g./m²
CaC0₃=22%
Porosity=50 sec.

Cigarettes in accordance with Examples 1 through 4 inclusive are simple to manufacture by conventional cigarette-making machinery, inasmuch as the only difference between these two cigarettes and conventional cigarettes is in the nature of the paper used to wrap the tobacco.
A cigarette using a low-porosity wrapper with a low filler content has the further advantage that it burns more slowly than a conventional cigarette, and therefore consumes less tobacco in a given number of puffs. It is not known whether or not any health benefits result directly from the reduced rate of consumption of tobacco. However, the reduction in tobacco consumption makes it possible to use less tobacco in a cigarette of a given length, and to provide a longer and more effective filter.
While the use of low-porosity paper with a low filler content improves fire resistance, it has comparatively little effect on sidestream smoke production. However, in accordance with the invention, it is a simple matter to reduce sidestream smoke to very low levels by treating paper having low porosity and low filler content with water or ethyl alcohol, and thereafter drying the paper. A cigarette so treated meets the necessary burning criteria in that it burns for at least one minute without puffing, and has a linear burn rate in the range of about 1-6 mm per minute.
Treatment of cigarette paper with water or ethyl alcohol is carried out simply by running the cigarette paper over and under rollers into a water or alcohol bath, and from there to a dryer which eliminates excess moisture or liquid content, bringing the moisture content of the cigarette paper back to its approximate original level.
The following two examples pertain to the treatment of low-porosity cigarette paper with water or ethyl alcohol.

Example 5

Weight=₂₇ g._/m ²
CaC0₃=18.5%
Porosity=50 sec.
Treatment=soak paper with water and allow to dry before wrapping tobacco.

Example 6

Weight=27 g./m²
CaC0₃=18.5%
Porosity=50 sec.
Treatment=soak paper in 95% ethyl alcohol and allow to dry before wrapping tobacco.

Depositing a linear burn rate reducing substance in or on the paper further improves fire resistance and, in some cases, also produces a further reduction in sidestream smoke. Deposition of the linear burn rate reducing substance can be carried out most conveniently, using a method similar to Example 5, by dissolving or suspending the substance in the water in which the cigarette paper is soaked. A wide variety of substances can be used to reduce the linear burn rate of low-porosity cigarette paper. Examples of suitable treatments include the following. In each case, the weight of the cigarette paper was 27 g./m², its CaC0₃ content was 18.5%, and its porosity was 50 seconds. The paper was soaked in an aqueous solution of the linear burn rate-reducing substance, and allowed to dry before wrapping the tobacco.
In each of Examples 7-12 the effect of the linear burn rate-reducing substance was to reduce the charring of the material used in the fire resistance test. The low end of the range of concentrations is the approximate point at which a noticeable reduction in charring occurs. Increasing the concentration to a level above the minimum effective level produces little improvement and therefore there is no reason to use higher concentrations of burn rate-reducing substances, except in the case of magnesium acetate, where raising the concentration to 3% results in a noticeable further reduction in sidestream smoke. Increasing the concentration of any of these burn rate-reducing substances to levels significantly higher than the upper ends of the given ranges may have a detrimental effect on the appearance and texture of the cigarette paper.
There are many other linear burn rate reducing substances which can be applied to low-porosity cigarette paper from an aqueous solution. These include, for example, trisodium phosphate, disodium phosphate, diammonium phosphate, phosphoric acid, sulfuric acid, sodium hydroxide, borax, boric acid, ammonium hydroxide, nickel acetate, sodium silicate, ammonium sulfate, ammonium sulfamate and sodium dichromate. These substances should be applied in low concentrations, i.e. of the order of 1 %, as higher concentrations tend to produce a darkening of the cigarette ash. (The substances of Examples 7-12 have little if any effect on ash coloration regardless of concentration).
Any of the burn rate-reducing substances can be applied in very low concentrations by multiple treatment steps. That is, the paper is soaked in a solution containing a low concentration of a burn rate reducing substance, allowed to dry, then soaked again in the same or another solution of a burn rate-reducing substance, and again allowed to dry.
Non-fat milk is also effective as a linear burn rate reducer for reducing charring of the material used in the fire resistance test. Non-fat milk can be conveniently applied as a suspension of non-fat dry milk in water. A typical analysis of non-fat dry milk (Carnation brand) is as follows:

Water 3.16%
Protein 36.16%
Lipids 0.77%
Carbohydrates 51.98%
Ash 7.93%

Example 13

Cigarette paper with a Greiner porosity of 50 seconds, a weight of 27 g./m^z and a CaC0₃ content of 18.5% was treated on one side in a suspension consisting of about 1% by weight of non-fat dry milk in water, and allowed to dry. This treatment leaves a glaze on the treated side of the paper. In the fire resistance test, the cigarette using the treated paper produced noticeably less charring and no smoldering of the test material than did a similar cigarette using untreated paper.
The concentration of non-fat dry milk can range from about 1% to about 20%, although higher concentrations within this range are not necessary. If a glazed appearance is not desired on the outside of the cigarette wrapper, the milk suspension can be applied to the side of the wrapper which ultimately faces toward the tobacco. Alternatively, both sides of the paper can be treated. Instead of non-fat dry milk, skim milk diluted with water can be used with equivalent effect.
Various insoluble linear burn rate reducing substances other than milk can be applied in a suspension. Examples of such substances are alumina gel, potato starch and aluminum stearate. A typical aqueous suspension of one of these substances contains about 1% by weight of the substance. When applied to low-porosity cigarette paper, these substances provide improved resistance to charring and smoldering as well as some sidestream smoke reduction.
While cigarettes with low-porosity paper do not tend to reduce the quantity of tar, this can be corrected by providing venting holes surrounding the filter in the conventional manner. Venting holes do not affect the fire resistance or sidestream smoke production of the cigarette.
Low-porosity wrappers have a relatively small effect on the draw characteristics of a cigarette, making it only slightly more difficult to draw a satisfactory amount of smoke into the mouth than in the case of an ordinary cigarette. The draw characteristics of all cigarettes in accordance with this invention, whether they be low tar, very low tar or high tar cigarettes, is acceptable and comparable to that of conventional cigarettes. In no event is the draw of a modified cigarette so difficult as to be seriously objectionable to ordinary smokes of that particular cigarette in its unmodified condition.
The use of non-fat dry milk as a burn rate reducer has a number of advantages over the use of other burn rate reducers such as citric acid, magnesium citrate, etc. The treated cigarette has a better appearance, and is smoother and easier to remove from the pack. It is resistant to moisture and has a longer shelf life, and its paper is more flexible than other treated papers. Furthermore, the paper retains its strength while wet during treatment with the non-fat dry milk suspension.
Where the paper is treated with a burn rate-reducing substance, it may be desirable from the standpoint of appearance of the cigarette, to apply the burn rate-reducing substance to one side of the cigarette paper, and to wrap the tobacco with this cigarette paper so that the treated side is toward the tobacco. These steps are especially desirable where the burn rate-reducing substance is in suspension or in solution in a relatively high concentration such as to form a visible deposit on the paper. These steps are also desirable because, with the treated side toward the tobacco, there is less tendency for the burn rate-reducing substance to affect the color of the cigarette ash. Higher concentrations of burn rate reducers can be used when the treated side of the paper is toward the tobacco. This method of treatment produces more effective smoke reduction and more effective fire resistance without materially affecting the appearance of the cigarette or its ash.
It is not necessary to treat the entire surface area of a sheet of cigarette paper in order to obtain the benefits of my invention. In fact, it is desirable to apply the burn rate-reducing substance to only a part of the surface area of the paper so that the porosity of the untreated areas serves to control the amount of tar and nicotine delivered in each puff.
In paper treatments over only part of the paper's surface area, performance is affected to some extent by paper porosity, the amount of burn accelerator present in the paper or tobacco, and the tobacco composition. Performance of a filter cigarette is also affected by the presence or absence of perforations in the paper surrounding the filter of the cigarette or the porosity of that paper. Similarly, the performance of non-filter cigarettes is affected not only by paper porosity but also by the presence or absence of perforations near the end of the cigarette closest to the smoker's mouth. In general, cigarettes can be classified as "high tar" cigarettes or "low tar" cigarettes depending on the above factors. Low tar cigarettes produce 15 mg or less tar under standard tests used in the tobacco industry. High tar cigarettes produce tars from above 15 mg. to 28 mg. or more. The effect of partial treatments in accordance with this invention has been found to correlate with the tar content classification of cigarettes.
I have found that with low tar cigarettes, a greater quantity of burn rate reducer is needed to effect sidestream smoke reduction than with high tar cigarettes. I have also found that high tar cigarettes with low-porosity paper require somewhat less treated area for sidestream smoke reduction than low tar cigarettes with low-porosity paper. However, if the high tar characteristic of a cigarette results from the absence of burn acceleration of the tobacco or from the burning characteristics of the tobacco the classification of the cigarette as a "high tar' or "low tar" cigarette has little bearing on the effect of area coverage in determining sidestream smoke reduction.
Treatment with milk as a burn rate reducer is different in that high concentrations of milk, while producing good fire resistance, tend to cause more sidestream smoke than intermediate concentrations.
Treatment of cigarette paper in multiple successive steps given rise to certain advantages. In particular effective sidestream smoke reduction and fire resistance can be achieved using low concentrations of burn rate reduces in solution or suspension. Porosity control can be achieved by partially covering the cigarette paper with a burn rate reducer in one step and good sidestream smoke reduction and fire resistance is insured by applying a burn rate retardant in a very low concentration over the entire area of the paper in a separate step. Desirably, although not necessarily, the partial coverage step is carried out by application of the burn rate reducer to the side of the paper which ultimately faces the tobacco, as this results in a cigarette having a better appearance.
An additional layer of conventional cigarette paper can be used to improve the performance of a cigarette using low-porosity paper. The use of an additional layer of cigarette paper in a cigarette having low-porosity paper is illustrated by the following example:

Example 14

This cigarette had an inner wrapper having the following characteristics:

Weight: 24 g/_cm ²
CaC0₃: 20%
Porosity: 50 sec.

Weight: about 24 g/m²
CaC0₃: about 25%
Porosity: 20 sec.

I have found that the inclusion of an additional wrapper improved the performance of cigarettes using burn rate-reducing substances other than magnesium citrate. I have also found that the treated wrapper can be placed on the outside, and the untreated wrapper on the inside without materially affecting the performance of the cigarette. An additional wrapper can be used with a cigarette the wrapper of which is treated over part of its area as described above, with similar improved results.
In all cases of cigarettes which are treated with burn rate reducers in the group consisting of citric acid, magnesium citrate, magnesium acetate, tartaric acid, acetic acid, lactic acid, a sugar, or a suspension of non-fat milk or skim milk, the concentrations of these primary burn rate reducing substances can be reduced without impairing performance if other burn rate reducing agents are present. Examples of applicable burn rate reducing agents which may be added are monoammonium phosphate, diammonium phosphate, ammonium sulfamate, boric acid, and sulfamic acid. For example, instead of using 22% citric acid on a conventional porous 25 mm cigarette, similar results in fire resistance, sidestream reduction and ash coloration are produced by treating the cigarette wrapper with a solution composition about 9% citric acid and 5% ammonium sulfamate.

Claims

1. A cigarette comprising a charge of tobacco in a cigarette paper wrapper having a Greiner porosity of about 50 or more seconds, the cigarette paper having a weight between about 10 and 35 grams per square meter and being substantially free of burn accelerator other than filler, the filler content of the paper being in the range of approximately 15 to 22 per cent.

2. A cigarette according to Claim 1 in which the wrapper is prepared by coating at least part of the surface of said cigarette paper with water or ethyl alcohol and thereafter drying said cigarette paper.

3. A cigarette according to Claims 1 or 2 in which the wrapper is prepared by depositing a linear-burn-rate-reducing substance in or on the paper by coating at least part of the surface of the paper with a solution or suspension of said substance.

4. A cigarette according to Claim 3 in which the wrapper is prepared by depositing a linear-burn-rate-reducing substance in or on the paper by coating at least part of the surface of the paper with a solution of citric acid, magnesium citrate, magnesium acetate, tartaric acid, acetic acid, lactic acid or a sugar, or a suspension of non-fat milk or skim milk.

5. A cigarette according to any of Claims 1 to 4 having an additional layer of paper in contact with substantially the entire surface area of said wrapper on one side thereof, said additional layer of paper being a cigarette wrapper having a Greiner porosity of about 10 to 40 seconds, a weight between about 10 and 35 grams per square meter, and a filler content in the range of approximately 22 to 35 percent.

6. The process of making a cigarette wrapper comprising coating, with water or in ethyl alcohol, at least part of the surface of a cigarette paper having a Greiner porosity of about 50 or more seconds and a weight between about 10 and 35 grams per square meter, said paper being substantially free of burn accelerator other than filler and having a filler content in the range of approximately 15 to 22 percent.

7. The process according to Claim 6 including the step of bringing into contact with the surface of said cigarette paper an additional layer of paper, said additional layer of paper being a cigarette wrapper having a Greiner porosity of about 10 to 40 seconds, a weight between about 10 and 35 grams per square meter, and a filler content in the range of approximately 22 to 35 percent.

8. The process according to Claim 6 or 7 in which the water or ethyl alcohol carries a linear burn rate-reducing substance and in which the linear burn rate-reducing substance is deposited on or in the paper.

9. The process according to Claim 8 in which the water or ethyl alcohol carries a linear burn rate-reducing substance from the group consisting of citric acid, magnesium citrate, magnesium acetate, tartaric acid, acetic acid, lactic acid, a sugar, non-fat milk and skim milk, and in which the linear burn rate-reducing substance is deposited on or in the paper.