Wrapper for smoking articles

Tobacco product wrapper, tobacco product and method

Other products, tobacco product and tobacco product

The present invention relates to a cover for tobacco products such as cigarettes, cigars and the like, which consists of a cellulosic sheet containing magnesium hydroxide and magnesium oxide as a filler.

A problem with tobacco products such as cigarettes and cigars is the amount of sidestream smoke emitted during static combustion when, for example, the tobacco product burns spontaneously without being smoked by a smoker or when it simply rests in an ashtray and burns. For example, visible sidestream smoke from a cigarette-like tobacco product during static combustion irritates and disturbs non-smokers in the vicinity of the rolling cigarette.

The problem with coatings that have developed so far with little side stream smoke is that they form flakes and / or color defective ash due to the poor cremation or incineration properties of the coatings. Various mechanisms have been added to tobacco products to reduce visible sidestream smoke and improve the ashing properties of coatings, but so far none have been able to commercially eliminate both of these problems.

Probably the most effective way to reduce visible sidestream smoke is heretofore disclosed in U.S. Patent 3,321,377 to Cline et al., Owned by Olin Corporation, a splitter transducer.

This patent discloses a coating for tobacco products such as cigarettes, cigars and the like containing at least 15% by weight of magnesium oxide or a hydrate thereof and at least 0.5% by weight of a certain chemical excipient such as precious metal acetates, carbonates, citrates, nitrates or tartrates. The incorporation of magnesium oxide or a hydrate thereof into a chemical excipient significantly reduces the visible sidestream smoke emanating from the coated tobacco products during static combustion. The wrapper may be conventional cigarette paper to which magnesium oxide and an excipient have been added as a filler to the fibrous material of the paper, or one or both of the additives may be applied to the paper as a wrapper. Additive-containing coatings may be used in place of conventional tobacco product coatings or may be used as the inner wrapper of a tobacco rod in combination with a conventional outer wrapper of cigarette paper or cigar wrapper.

This patent makes it possible to achieve a considerable and very advantageous reduction in visible sidestream smoke by using cigarette paper containing magnesium oxide as a filler in combination with certain chemical excipients. These papers have consistently produced flaky ash and have been declared unusable by cigarette manufacturers due to poor ash properties. Even in large-scale experiments, no chemical excipient or combustible chemical or combination thereof has been found to eliminate this problem.

The more reactive species of magnesium oxide, which are highly effective fillers to reduce side flow, are at least partially converted to magnesium hydroxide during the papermaking process. One example of such a product is MagChem 40, manufactured by Martin Marietta Company, which produces highly flaky cigarette paper ash. In contrast, hard-burned, unreacted magnesium oxide MagChem 10, manufactured by the same company, produces white, solid ash that shrinks and stays together well. This unreacted oxide hydrates to form magnesium hydroxide only very slowly at ambient temperatures and remains substantially unchanged in the finished paper when used as a filler. Papers filled with unreacted magnesium oxide do not reduce sidestream smoke more than is achieved with the corresponding high basis weight amounts of calcium carbonate and fire rate accelerators.

These facts lead to the conclusion that magnesium hydroxide is an essential ingredient in order to achieve the best possible side flow reduction. It was speculated that if the effect of magnesium hydroxide on cigarette combustion was due to its endothermic dehydration at about 350 ° C, the yield of sidestream tar should be inversely proportional to the amount of magnesium hydroxide present in the paper. It has been said that this is not entirely true. In this case, MagChem 40, which is fully hydrated by soaking in water overnight, is no more effective than when used without pretreatment to make hand-made test sheets. About 50% of the untreated filler was converted to magnesium hydroxide during the test sheet manufacturing process. Likewise, the powdered magnesium hydroxide used as the sole filler component did not reduce the side flow more than the partially hydrated oxide and formed a darker, very flaky ash.

It is an object of the present invention to provide an improved cellulosic coating for tobacco products which has less sidestream smoke and which produces solid non-flaky ash.

It is a further object to provide an improved cellulosic wrapper and wrapped tobacco products that avoid the cost and potential hazards of adding inorganic fibers to the wrapper to form flaky ash.

These objects and advantages have been achieved according to the invention in that the average particle size of the magnesium hydroxide is less than 10 μm and that the magnesium oxide is unreacted. In this case, as the amount of filler added to the paper increases, a point is reached where the additional amounts of magnesium hydroxide no longer touch the fibrous surfaces, but deposit on top of the already added filler, forming larger aggregates. In this case, the small particle size magnesium hydroxide should be able to effectively cover the fibrous surfaces so that the total magnesium hydroxide content in the sheet is lower.

Since poor ash has been found to be associated with the magnesium hydroxide content of the sheet, it should be possible to achieve both ash improvement and low sidestream smoke output by using an inert filler such as MagChem 10 (unreacted magnesium oxide) and a small amount of magnesium hydroxide less than 10. Experiments have shown that this can be done.

The invention then includes an improved cigarette paper product which greatly reduces the amount of sidestream tar and visible sidestream smoke, while forming a light and solid ash of color that tends to adhere to the tobacco product and not flake off. The paper filler consists of a mixture of a large amount of unreacted magnesium oxide or other inert fillers and a small amount of magnesium hydroxide having a particle size of less than 10. The paper should also contain a chemical accelerator to accelerate the rate of combustion, as disclosed in U.S. Patent 4,321,377.

The accompanying drawing is a diagram showing the sidestream tar yields labeled against the porosity of the experiments shown in Example III.

Cellulosic coatings made in accordance with this invention can be prepared by adding magnesium hydroxide and unreacted magnesium oxide fillers to the fibrous material of the coating.

In addition, other inert fillers such as calcium carbonate may be used in combination with Mg (OH) 2 and MgO.

Mg (OH) 2 and MgO fillers can be applied to the coating according to the invention as a coating, but this is not advantageous because this does not result in equal contact between the fillers and the paper fiber. In the case of cigarette papers, fillers and magnesium hydroxide are added to the conventional fibrous material of the paper, such as wood pulp or flax pulp fibers. The fibrous pulp, magnesium hydroxide and fillers are then used to make a sheet of paper in conventional paper machines.

Magnesium hydroxide and fillers can be added to the pulps commonly used to make cellulosic paper wrappers for cigarettes or to tobacco materials used to make a cigar wrapper. In this case, in addition to the wood and flax fibers, the fibrous material may consist of ground tobacco straw or stalks to which a small percentage of fine-grained magnesium hydroxide and unreacted magnesium oxide are added.

The tobacco product wrappers of the invention, which contain a small percentage of magnesium hydroxide and unreacted magnesium oxide with or without other fillers, can be used as the inner wrapper under the normal outer wrapper of a cigarette or cigar tobacco rod. Conventional cigarette paper and preferably highly porous or perforated cigarette paper or cigar wrapper can be used as the outer wrapper of the tobacco product. Such a combination can reduce the weight of tobacco required to make a satisfactory product, increase the strength of the tobacco rod, and not alter the appearance of the cigarette or cigar. Coatings containing additives according to the invention can also be used as a single coating for tobacco products. In connection with cigarettes, it is particularly advantageous to use papers with a high basis weight if only one wrapper is used.

As discussed above, some reduction in sidestream smoke is achieved and the appearance of the ash is improved by using these fillers in typical amounts of cigarette paper and weight of about 30%, which in turn is about 25 g / m 2.

The best results are achieved with basis weights of 40 g / m

100 g / m 2 and 40-60% of the total fillers. The concentration of magnesium hydroxide in the filler depends on e.g. its particle size, but is generally between 5-50% or 2.5-25% of the total weight of the sheet when the total amount of filler in the paper is 50%. For best results, the coatings should also contain at least 0.5% and preferably 2% or more of at least one of the burn rate accelerating chemical excipients disclosed in U.S. Patent 4,231,377.

The following examples illustrate the invention and all the test sheets shown therein were prepared with a total filler content of 50% and a basis weight of 100 g / m 2. All were treated in a surface sizing machine with 3.0% sodium acetate. The cigarettes were rewrapped using the corresponding weight and Kentycky Referee 1R3 tobacco. With the exception of the separately marked sections, flax obtained from the same whipping operation was used for all test sheets in each example.

Example no 1

Hydromagma is a magnesium hydroxide paste manufactured by Merck and Company and has an average particle size of much less than 1 μm. This example compares mixtures of hydromagma and MagChem 10 (unreacted magnesium oxide) with similar mixtures of MagChem 10 and a dry powdered magnesium hydroxide sample (supplied by Basic, Incorporated), the latter having a particle size of about 10. The results are tabulated as follows:

Greiner porosity (seconds / 50 cm3)

Filler mixture

Side tar tar mg / cigarette

Average burning time (min.)

MagChem 10 /%

<td>25% hydromagma</td><td> 61,0</td><td> 9,6</td><td> 13,8</td>

<td>50% MagChem 10 / 50% hydromagma</td><td> 112,0</td><td> 9,8</td><td> 14,6</td>

<td>75% MagChem 10 / 25% magnesium hydroxide powder</td><td> 22,9</td><td> 13,0</td><td> 10,4</td>

<td>50% MagChem 10 / 50% magnesium hydroxide powder</td><td> 19,2</td><td> 12,3</td><td> 9,9</td>

<td>100% MagChem 40 * (comparison)</td><td> 16,3</td><td> 10,3</td><td> 9,4</td>

The comparison of the two forms of magnesium hydroxide is slightly hampered by the fact that different flax pulp was used in the two cases. However, it is clear that magnesium hydroxide with a smaller particle size is more effective in reducing sidestream tar. The ash from all papers with blend fillers was much firmer and lighter in color than that obtained from the comparison.

* (MagChem 40, manufactured by Martin Marietta Company, is a reactive form of magnesium oxide that is partially converted to magnesium hydroxide during the papermaking process).

Example no 2

In this series of test sheets, MagChem 10 was again used as an unreacted portion of the filler along with varying amounts of magnesium hydroxide, which had been separated from the suspension supplied by Merck and Company and was designated R1458. The average particle size of this magnesium hydroxide was larger than the hydromagma of the previous example, but still less than 1. The results are tabulated as follows:

<td>Percentage of magnesium hydroxide in the filler</td><td>Greiner porosity _?(sec./50 cni)</td><td>Side flow tar (mg / cigarette)</td><td>Average burning time (minutes)</td>

<td> 25</td><td> 25,0</td><td> 11,3</td><td> 10,4</td>

<td> 20</td><td> 22,8</td><td> 11,5</td><td> 9,7</td>

<td> 15</td><td> 22,0</td><td> 11,6</td><td> 9,8</td>

<td> 10</td><td> 20,6</td><td> 12,0</td><td> 9,6</td>

<td> 5</td><td> 20,9</td><td> 14,5</td><td> 9,5</td>

<td>MagChem 40</td><td></td><td></td><td></td>

<td>comparison</td><td> 10,5</td><td> 9,6</td><td> 9,9</td>

As in Example 1, all papers with blended filler gave a lighter colored and less flaky ash than the MagChem 40 comparison.

Example no 3

In this example, mixtures of MagChem 10 and four different types of magnesium hydroxide in a ratio of 75:25 were used to silence test sheets from three different flax pulps processed to different weight lengths and greases. The magnesium hydroxides used in this study were hydromagma paste; R1458 suspension; Basic Incorporated company's dry powder; and another dry powder of similar particle size, manufactured by Merck and Company, called Marinco H. The results are shown graphically in the drawing, in which the sidestream tar yields are shown against porosity, which correlates with the degree of refining. Although other factors may cause some minor differences, the particle size of magnesium hydroxide is clearly the most important variable affecting by-pass yield. In this case, the curves of the hydromagma paste and the R1458 suspension, which are much smaller in particle size, are located close to each other and clearly below the curves of the two dry powders with larger particles.

Example no 4

Two aqueous dispersions of magnesium hydroxide supplied by Dow Chemical Company were used in this example. One of these is a commercial product called MHT-60 and has an average particle size between 5 and 10. The second micronized (wet-milled) version of MHT-60 had an average particle size of less than 1.0 μm, and the other ingredient in the filler was either MagChem 10 magnesium oxide or calcium carbonate bagged by the Mississippi Lime Company. The test results for cigarettes wrapped in these papers are tabulated as follows:

Filler mixture

Greiner porosity ^. (sec./50 cm)

Side flow tar (mg / cigarette)

Average burning time (minutes)

75% MagChem 10/25% MHT-60

<td>(micronized)</td><td> 17,0</td><td> 11,5</td><td> 9,3</td>

<td>75% MagChem 10 / 25% MHT-60</td><td> 10,0</td><td> 13,6</td><td> 10,3</td>

<td>75% calcium carbonate 25% MHT-60 (micronized)</td><td> 17,5</td><td> 13,0</td><td> 9,9</td>

<td>75% calcium carbonate 25% MHT-60</td><td> 12,5</td><td> 13,3</td><td> 10,0</td>

<td>100% MagChem 10 comparison</td><td> 9,3</td><td> 18,7</td><td> 10,3</td>

When used in combination with MacChem 10, the smaller particle size micronized MHT-60 was more effective in reducing sidestream tar emissions. This effect was not seen in the mixtures containing calcium carbonate. These fillers significantly reduced side flow more than the MagChem 10 comparison. All of the test sheets in this example gave a lighter colored ash than paper made with magnesium hydroxide or some degree of reactive magnesium oxide as the sole filler.

Cellulose wrappers for tobacco products are made with fillers containing fine-grained magnesium hydroxide and unreacted magnesium oxide. In addition, other inert fillers such as calcium carbonate may be used in the fibrous material of the coating composition. Magnesium hydroxide and unreacted magnesium oxide can be applied to the coating of the invention as a coating, although this is less effective. In the case of cigarette papers, the materials are added to a conventional paper fibrous material, which may consist of wood cellulose fibers or flax fibers. The fibrous material, magnesium hydroxide and magnesium oxide fillers are then used to make a sheet of paper in conventional paper machines.