Technical Field

The present invention relates to a wrapping paper for a smoking article that has a low ignition propensity and a smoking article comprising a wrapping paper that has a low ignition propensity.

Background Art

When a burning smoking article is left on furnishings and equipment, such as a couch or a bed, it could cause a fire. In order to prevent this, several approaches are known from the state of the art to cause a smoking article to self-extinguish. These types of smoking articles are generally known as "low ignition propensity" smoking articles. However it is undesirable to have a smoking article self-extinguish while a smoker is using it.

US 2013/104,915 teaches a cigarette paper that provides a cigarette manufactured therefrom with self-extinguishing properties, wherein the base paper has a C0 ₂ diffusivity of less than 0.35 cm/s and the cigarette paper comprises at least one discrete area, wherein this area is perforated and has an air permeability greater than the air permeability beyond the perforated area.

US 2016/198,761 relates to a cigarette paper with self-extinguishing properties that has treated areas, onto which a composition is applied that contains filler particles or a mixture of filler particles, wherein the diffusion capacity in the treated areas is less than in an untreated area of the cigarette paper. In this regard, at least 20% by weight of the filler particles in the treated areas are formed by a filler with a flaked shape, a filler with a scalenohedral crystal structure, a filler with a rhombohedral crystal structure, or a filler with a cubic shape.

To prevent a fire and to suppress sidestream smoke, Japanese Utility Model No.

3049857 discloses a cigarette wherein the length of the tobacco rod is half that of the ordinary cigarette. Also Japanese Patent Application KOKAI No. 7-327654 discloses a cigarette wherein the length of the tobacco rod is decreased to 1 to 1 .5 cm in order to prevent a fire and to suppress the sidestream smoke. These cigarettes having a shorter than usual tobacco rod provide a number of puffs considerably smaller than that provided by the cigarette available on the market.

The problem of the present invention is to provide a wrapping paper for a smoking article that has a low ignition propensity and a reduced impact on taste.

l Brief description of the invention

The inventors have found that by providing a wrapping paper for a smoking article with a plurality of burn-suppressing regions and a certain ratio of diffusion capacity between the burn-suppressing regions and the base paper, i.e. the non-burn-suppressing regions, it is possible to obtain a low ignition propensity smoking article with a reduced impact on taste.

A first aspect of the present invention relates to a wrapping paper comprising a base paper, where the base paper comprises a plurality of burn-suppressing regions that are provided apart from each other, wherein the ratio of diffusion capacity between the burn- suppressing regions and the base paper, i.e. the non-burn suppressing regions, is in the range of 5% to 35%.

In another aspect of the present invention, a smoking article is disclosed comprising a charge of smokable material surrounded by a wrapping paper according to the first aspect of the invention. The smoking article is in particular a low ignition propensity smoking article.

Further aspects and embodiments of the invention are disclosed in the dependent claims and can be taken from the following description and examples, without being limited thereto.

Figures

The enclosed drawings should illustrate embodiments of the present invention and convey a further understanding thereof. In connection with the description it serves as explanation of concepts and principles of the invention. Other embodiments and many of the stated advantages can be derived in relation to the drawings.

FIG. 1 is a schematic perspective view, partly broken away, showing an example of a cigarette that is wrapped with a cigarette paper having stripe-shaped burn-suppressing regions according to one embodiment of the present invention.

The cigarette 10 has a tobacco rod 1 1 consisting of a tobacco filler 13 that is wrapped with a wrapping paper 12 of the present invention in the form of a column. An ordinary filter 15 may be attached to the proximal end (namely, the downstream end in the inhaling direction) 1 1 b of the tobacco rod 1 1 by using a tipping paper 14 according to a conventional method.

A plurality of stripe-shaped burn-suppressing regions 122, which are coated as will be explained in the forthcoming description, are formed on one of the surfaces of the base paper 121 that constitutes the wrapping paper 12 of the present invention. These stripe- shaped burn-suppressing regions 122 are formed apart from each other in the

circumferential direction of the tobacco rod 1 1 .

Non-burn-suppressing regions 123 are formed between the adjacent stripe-shaped burn-suppressing regions 122. Since the regions 123 are constituted by a part of the base paper 121 , they can burn in an ordinary smoking state. Therefore, the regions 123 each act as a non-burn-suppressing region. For example, the stripe-shaped burn-suppressing regions 122 each may have a width of 1 to 6 mm in the circumferential direction. The distance between the adjacent burn-suppressing regions 122 may be 2 to 20 mm.

In the cigarette shown in FIG. 1 , a non-burn-suppressing region 124 may be provided to the region covering a distance d from the tip 1 1 a of the base paper 121 .

FIG. 2 is a schematic perspective view, partly broken away, showing an example of a cigarette that is wrapped with a cigarette paper having annular band-shaped burn- suppressing regions according to another embodiment of the present invention.

The cigarette 20 has a similar structure to that of the cigarette 10 shown in FIG. 1 , except for the structure of the burn-suppressing regions in the wrapping paper. Therefore, in FIG. 2, an identical reference number is assigned to the same element as the constitutional element in FIG. 1 , and the explanation thereof is omitted.

In the cigarette 20 shown in FIG. 2, a plurality of annular band-shaped burn- suppressing regions 21 1 are formed on the base paper 121 of the wrapping paper 21 wrapping the tobacco filler 13, defining burn-suppressing regions. These annular band- shaped burn-suppressing regions 21 1 are formed apart from each other in the longitudinal direction of the tobacco rod 1 1 .

Non-burn-suppressing regions 212 are formed between the adjacent annular band- shaped burn-suppressing regions 21 1 . Since the non-burn-suppressing regions 212 are constituted by a part of the base paper 121 , they can burn in an ordinary smoking state. Therefore, the regions 212 each act as a non-burn-suppressing region, as the regions 123 in FIG. 1 do. For example, the annular band-shaped burn-suppressing regions 21 1 each may have a width of 4 to 7 mm in the longitudinal direction. The distance between the adjacent burn-suppressing regions 24 may be 18 to 25 mm.

Detailed description of the invention

Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

All values given in the present disclosure are to be understood to be complemented by the word "about", unless it is clear to the contrary from the context.

Smoking articles as referred to herein are not particularly limited and can for example be cigarettes, cigarillos or the like. They typically have a generally cylindrical rod shaped configuration and include a charge, roll, or column of smokable material, such as shredded tobacco (e.g. in cut filler form), which is surrounded by a paper wrapper forming a so-called "tobacco rod". A cigarette or cigarillo usually also has a cylindrical filter element aligned in end-to-end relationship with the tobacco rod. The filter element may, for example, comprise a plug of cellulose acetate tow, and the tow is circumscribed by a wrapper material known as "plug wrap". Typically, the filter element is attached to one end of the tobacco rod using a circumscribing wrapping material known as "tipping wrapper". The filter element wrapped by the tipping wrapper is known as "mouthpiece element".

As used herein, wt.-% is to be understood as weight percent, based on the dry weight of the base paper, unless explicitly otherwise specified. In the present disclosure, all amounts given in wt.-% in a particular embodiment add up to 100 wt.-%. The weight percent are thereby calculated by dividing the mass of each component by the dry mass of the base paper.

As used herein, a "low ignition propensity" smoking article is one that has been designed to be less likely than a conventional cigarette to ignite furnishings and equipment, e.g. soft furnishings such as a couch or mattress. Ideally, a low ignition propensity smoking article will continue to burn when freely suspended such as in the holder of an ashtray or when being held in the hand without puffing ("free burn"). The tendency for a cigarette to go out during free burn is referred to as "self-extinguishment".

The capability of a smoking article to extinguish or to generate sufficient heat to continue burning, and thus potentially cause ignition of bedding or upholstered furniture (referred to as LIP) may be measured by any suitable method. In the present invention this is done according to ISO 12863:2010.

The likelihood of a smoking article to extinguish while burning in free air (referred to as FASE) may be measured by any suitable method. In the present invention this is done according to ISO 12863:2010.

TNCO levels as referred to herein stand for tar, nicotine and carbon monoxide levels and can be measured by any suitable method. In the present invention this is done according to ISO 3308:2012.

The symbol "CU" herein designates the CORESTA air permeability unit that is commonly used in paper specifications by smoking article designers. The CORESTA air permeability unit is defined as: "the volumetric flow rate of air in cubic centimeters per minute (cm3/min) passing through a 1 square centimeter (cm2) sample of substrate at an applied pressure difference of 1 kilo-Pascal (kPa)." and are measured according to ISO 6565:201 1 .

The number of puffs of a smoking article may be measured by any suitable method. In the present invention this is done according to ISO 3308:2012.

The diffusion capacity of a wrapping paper is measured in the present invention according to CORESTA Recommended Method No. 77 (CRM No. 77) of April 2014. The present invention relates to a wrapping paper for a smoking article comprising a base paper, wherein the base paper comprises a plurality of burn-suppressing regions that are provided apart from each other, wherein the ratio of diffusion capacity between the burn- suppressing regions and the base paper is in the range of 5% to 35%. By providing this ratio of diffusion capacity between the burn-suppressing regions and the base paper outside of the burn-suppressing regions (non-burn-suppressing regions) it is possible to provide a low ignition propensity smoking article with a reduced impact on taste. The wrapping paper is formed of a base paper with burn-suppressing regions provided therein. As the regions of the wrapping paper which are outside the burn-suppressing regions are to be considered as non- burn suppressing regions the latter being the same as the base paper, the present application uses the terms "non-burn suppressing regions" and "base paper"

interchangeably.

In certain embodiments of the present wrapping paper, the ratio of diffusion capacity between the burn-suppressing regions and the non-burn-suppressing regions, i.e. the base paper, is in the range of 10% to 35%, or 15% to 35%, or 5% to 30%, or 10% to 30%, or 15% to 30%, or 10% to 25%, or 15% to 25%.

In a particularly preferred embodiment, the ratio of diffusion capacity between the burn- suppressing regions and the non-burn-suppressing regions is in the range of 9% to 17%. It has been found that the impact on taste is particularly reduced in this range while the wrapping paper still exhibits a good LIP and FASE performance.

The burn-suppressing regions may be provided on a surface of the base paper or embedded within a matrix of the base paper. The plurality of burn-suppressing regions may be provided on a same surface of the base paper. Alternatively, one or more of the plurality of burn-suppressing regions may be provided on a first surface of the base paper and the remaining of the plurality of burn-suppressing regions may be provided on a second, opposite surface of the base paper.

The shape and amount of these burn-suppressing regions is not further limited and may vary according to the specific requirements of the smoking article. In certain

embodiments the burn-suppressing regions are in a form of stripes. In one embodiment all stripes are parallel to each other. In another embodiment at least two stripes are non-parallel to each other.

In certain embodiments of the present smoking article comprising a wrapping paper, when a tobacco rod is wrapped by the wrapping paper, the burn-suppressing regions are in a form of stripes extending in a longitudinal direction of the tobacco rod and being spaced apart from each other in a circumferential direction of the tobacco rod.

In certain embodiments of the present smoking article comprising a wrapping paper, when a tobacco rod is wrapped by the wrapping paper, the burn-suppressing regions are in a form of round annular bands extending in a circumferential direction of the tobacco rod and being spaced from each other in a longitudinal direction of the tobacco rod.

In certain embodiments of the present wrapping paper, the diffusion capacity of the base paper, i.e. the non-burn suppressing regions, is 1 .0 to 2.0 cm/s, e.g. 1 .0 to 1 .8 cm/s, or e.g. 1 .2 to 1 .6 cm/s, or e.g. 1 .2 to 2.0 cm/s, or e.g. 1 .2 to 1 .8 cm/s, or e.g. 1 .2 to 1 .6 cm/s, or e.g. 1 .4 to 2.0 cm/s, or e.g. 1 .4 to 1 .8 cm/s, or e.g. 1 .4 to 1 .6 cm/s.

In certain embodiments of the a wrapping paper, the diffusion capacity of the burn- suppressing regions is 0.10 to 0.35 cm/s, or e.g. 0.15 to 0.35 cm/s, or e.g. 0.20 to 0.35 cm/s or e.g. 0.10 to 0.30 cm/s, or e.g. 0.15 to 0.30 cm/s, or e.g. 0.20 to 0.30 cm/s, or e.g. 0.10 to 0.25 cm/s, or e.g. 0.15 to 0.25 cm/s, or e.g. 0.20 to 0.25 cm/s.

These burn-suppressing regions may contain additives that reduce the diffusion capacity of the base paper. The additives that may be applied to the wrapper may be any of those used in the art to reduce the ignition propensity of smoking articles.

In certain embodiments of the present wrapping paper, the burn-suppressing regions in the wrapping paper contain at least one additive that reduces the diffusion capacity of the base paper. The additives are optionally selected from the group consisting of alginates, polyvinyl alcohol, polyvinyl acetates, including partially hydrolyzed derivatives and

copolymers, modified and unmodified starches, cellulose derivatives, such as carboxy-methyl cellulose, ethyl-cellulose, hydroxymethyl-cellulose and combinations thereof. The additives may further comprise inorganic ions such as phosphates, mono- or divalent metal salts, silicas or mixtures thereof. The additives may yet further comprise natural gums, such as guar gum.

The additives may be applied to the wrapping paper with a liquid carrier, which may be in the form of a solution, suspension, emulsion or a combination thereof. The liquid carrier may be aqueous, non-aqueous or a combination thereof and may contain an emulsifying agent depending on the nature of the additives.

In one embodiment, a suspension of additive may be applied within an aqueous carrier. The aqueous carrier penetrates the base paper transporting the additive into its matrix. Once the carrier evaporates, the additive is left within the base paper matrix where it can reduce the diffusion capacity either before or during the burning of the smoking article. Once applied to the base paper, the liquid carrier is allowed to evaporate allowing the wrapping paper to dry and for the additive to set within the matrix of the base paper.

In certain embodiments of the present wrapping paper, the base paper comprises a fibrous material, a filler material, and one or more burning additives.

In certain embodiments of the present wrapping paper, the paper porosity of the base paper is 10 to 60 CU and a total amount of burning additive is 0.1 to 0.7 wt.-% based on the dry weight of the base paper. By providing a base paper with such porosity and amount of burning additive it is possible to increase the puff count of the smoking article without impacting on the TNCO levels nor changing the tobacco rod length or diameter.

In certain embodiments of the present wrapping paper, the paper porosity of the base paper is 10 to 50 CU, e.g. 15 to 45 CU. This further increases the puff count of the smoking article.

In certain embodiments of the present wrapping paper, the burning additive is included in the base paper in an amount of 0.2 to 0.6 wt.-%, e.g. 0.3 to 0.5 wt.-% based on the dry weight of the base paper. This further increases the puff count of the smoking article.

In certain embodiments of the present wrapping paper, the burning additive is selected from the group consisting of citrate salts, e.g. sodium and potassium citrate, acetate salts, e.g. sodium and potassium acetate, phosphate salts, e.g. sodium and potassium phosphate, tartrate salts, e.g. sodium and potassium tartrate, nitrate salts, e.g. sodium and potassium nitrate, or mixtures thereof.

The burning additive is not particularly limited, as long as it is suitable for use in a smoking article. In certain embodiments citrate salts are used.

In certain embodiments of the present wrapping paper, the amount of filler in the base paper is 17 to 28 wt.-%, e.g. 20 to 25 wt.-%, based on the dry weight of the base paper. This amount of filler provides an adequate resistance to manufacturing forces to which the wrapping paper is subject to during high speed manufacturing and also allows obtaining a desired opacity of the wrapping paper.

In certain embodiments of the present smoking article comprising a wrapping paper, the filler in the base paper is selected from the group consisting of calcium carbonate, such as precipitated calcium carbonate (PCC) or ground calcium carbonate (GCC), kaolin clay, talc, titanium dioxide, alumina trihydrate, and precipitated silica and silicates (PSS), or mixtures thereof.

Just like the burning additive, the filler is not particularly limited, as long as it is suitable for use in a smoking article. In certain embodiments calcium carbonate is used.

In one embodiment, the paper porosity of the base paper is 40 to 50 CU, e.g. 43 to 47 CU, e.g. 45 CU, the total amount of burning additive is in an amount of 0.4 to 0.6 wt.-%, e.g. 0.5 wt.-%, based on the dry weight of the base paper, and the amount of filler in the base paper is 17 to 23 wt.-%, e.g. 19 to 21 wt.-%, e.g. 20 wt.-%, based on the dry weight of the base paper.

According to certain embodiments, the balance to 100 wt.-% of the dry weight of the base paper is essentially filler and fibrous material.

In certain embodiments of the present wrapping paper, the basis weight of the base paper is 20 to 26 g/m ² , e.g. 21 to 24 g/m ² , or e.g. 23 to 25 g/m ² , e.g. 24 g/m ² . By providing a base paper with a basis weight comprised in these ranges it is possible to obtain a desired opacity of the wrapping paper while controlling the level of CO.

In certain embodiments of the present wrapping paper, the fibrous material is a cellulosic fibrous material.

The present invention further relates to a smoking article comprising a wrapping paper as in the embodiments described above and in which the wrapping paper surrounds a charge, roll or column of smokable material to form a tobacco rod.

In certain embodiments of the present smoking article, when a tobacco rod is wrapped by the wrapping paper, the burn-suppressing regions are in a form of stripes extending in a longitudinal direction of the tobacco rod and being spaced apart from each other in a circumferential direction of the tobacco rod.

In certain embodiments of the present smoking article, when a tobacco rod is wrapped by the wrapping paper, the burn-suppressing regions are in a form of round annular bands extending in a circumferential direction of the tobacco rod and being spaced from each other in a longitudinal direction of the tobacco rod.

The present invention relates to a wrapping paper comprising a plurality of burn- suppressing regions that are provided apart from each other on one surface of the wrapping paper, wherein the ratio of diffusion capacity between the burn-suppressing regions and the non-burn suppressing regions is in the range of 5% to 35%.

Without being bound to a certain theory, the positive effect of the present invention, i.e. the combination of a low ignition propensity without a deterioration of taste properties is due to the specific ratio of diffusion capacity between the burn-suppressing regions and the non- burn suppressing regions that are provided apart from each other at the base paper as laid out above.

The above embodiments can be combined arbitrarily, if appropriate. Further possible embodiments and implementations of the invention comprise also combinations of features not explicitly mentioned in the foregoing or in the following with regard to the examples of the invention. Particularly, a person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

Examples

The present invention will now be described in detail with reference to examples thereof. However, these examples are illustrative and do not limit the scope of the invention. Example 1

Two 84 mm cigarettes with increased puff count were prepared with the same tobacco blend. These cigarettes had both a 63 mm tobacco rod attached to a 21 mm filter by a tipping paper. The filters were cut from the same filter rod and the tipping papers were cut from the same reel. The tobacco rod of cigarette A was wrapped in a prior art wrapping paper (paper A), while cigarette B was wrapped in a wrapping paper according to the invention (paper B). In both wrapping papers the burn-suppressing regions were 6 mm wide annular bands separated between them by 18 mm in a construction similar to the one depicted in FIG. 2. The specifications of the respective wrapping papers are indicated in Table 1 below. Table 1

These cigarettes were measured under ISO 3308:2012 conditions to determine their TNCO levels as well as their respective puff counts. Self-extinguishment was also measured for these cigarettes, both when positioned on a surface (ISO 12863:2010 - referred to as LIP) and when burning in free air (ISO 12863:2010 - referred to as FASE). The results are shown in Table 2 below. It was found that wrapping paper B increased the puff count of cigarette B by 1 .3 while maintaining very similar TNCO levels. Paper B also shows a high self-extinguishing rate when positioned on a surface and a significantly improved

performance when burning in free air. A blind smoking test conducted with a panel of smoking experts was used to evaluate the impact on taste. The test consisted of providing one cigarette of each type to each panelist, who smoked them consecutively and then indicated which one tasted better. The panel of experts concluded that cigarette B has a better taste than cigarette A.

Table 2

Example 2

Two 84 mm low ignition propensity cigarettes were prepared with the same tobacco blend. These cigarettes had both a 57 mm tobacco rod attached to a 27 mm filter by a tipping paper. The filters were cut from the same filter rod and the tipping papers were cut from the same reel. The tobacco rod of cigarette C was wrapped in the prior art wrapping paper from example 1 (paper A), while cigarette D was wrapped in the wrapping paper according to the invention from example 1 (paper B).

These cigarettes were measured under ISO 3308:2012 conditions to determine their TNCO levels as well as their respective puff counts. Self-extinguishment was also measured for these cigarettes, both when positioned on a surface (ISO 12863:2010 - referred to as LIP) and when burning in free air (ISO 12863:2010 - referred to as FASE). The results are shown in Table 3 below. It was found that wrapping paper B increased the puff count of cigarette B by 0.9 while maintaining very similar TNCO levels. Paper B continues to show a high self-extinguishing rate when positioned on a surface and a significantly improved performance when burning in free air.

A blind smoking test conducted with a panel of smoking experts as in example 1 showed that cigarette D has a better taste than cigarette C. Table 3

Example 3 Four 84 mm cigarettes were prepared with the same tobacco blend. These cigarettes had both a 63 mm tobacco rod attached to a 21 mm filter by a tipping paper. The filters were cut from the same filter rod and the tipping papers were cut from the same reel. The tobacco rod of cigarette E was wrapped in a wrapping paper (paper C) with no burn-suppressing regions, which was used as a taste benchmark for the wrapping papers of the tobacco rods of cigarettes F, G and H (papers D, E and F, respectively) that do contain burn-suppressing regions. Wrapping papers D, E and F only differ from wrapping paper C in the presence of burn-suppressing regions and differ amongst each other in the diffusion capacity of the burn- suppressing regions. In wrapping papers D, E and F the burn-suppressing regions were 6 mm wide annular bands separated between them by 18 mm in a construction like the one depicted in FIG. 2. The specifications of the respective wrapping papers are indicated in Table 4 below.

These cigarettes were measured under ISO 3308:2012 conditions to determine their TNCO levels as well as their respective puff counts. Self-extinguishment was also measured for these cigarettes, both when positioned on a surface (ISO 12863:2010 - referred to as LIP) and when burning in free air (ISO 12863:2010 - referred to as FASE). The results are shown in Table 5 below. It was found that wrapping paper F continues to show a high self- extinguishing rate when positioned on a surface and a significantly improved performance when burning in free air when compared to wrapping papers D and E, while maintaining very similar TNCO levels to wrapping paper C.

Table 4

Table 5

A blind smoking test conducted with a panel of experts was used to evaluate the impact on taste. Each panelist received three reference cigarettes (cigarette E), and three test cigarettes, one of each type (F, G, H), grouped in pairs so that each pair would contain a reference cigarette and a test cigarette. The panelists smoked the pairs of cigarettes consecutively, and then indicated which of the test cigarettes was closer in taste to the reference cigarette. The smoking test concluded that cigarette H was closer in taste to reference cigarette E.

Example 4

Four 84 mm cigarettes were prepared with the same tobacco blend. These cigarettes had both a 63 mm tobacco rod attached to a 21 mm filter by a tipping paper. The filters were cut from the same filter rod and the tipping papers were cut from the same reel. The tobacco rod of cigarette I was wrapped in a wrapping paper (paper G) with no burn-suppressing regions, which was used as a taste benchmark for the wrapping papers of the tobacco rods of cigarettes J, K and L (papers H, I and J, respectively) that do contain burn-suppressing regions. Wrapping papers H, I and J only differ from wrapping paper G in the presence of burn-suppressing regions and differ amongst each other in the diffusion capacity of the burn- suppressing regions. In wrapping papers H, I and J the burn-suppressing regions were 6 mm wide annular bands separated between them by 18 mm in a construction similar to the one depicted in FIG. 2. The specifications of the respective wrapping papers are indicated in Table 6 below.

Table 6

These cigarettes were measured under ISO 3308:2012 conditions to determine their TNCO levels as well as their respective puff counts. Self-extinguishment was also measured for these cigarettes, both when positioned on a surface (ISO 12863:2010 - referred to as LIP) and when burning in free air (ISO 12863:2010 - referred to as FASE). The results are shown in Table 7 below. It was found that wrapping paper J continues to show a high self- extinguishing rate when positioned on a surface and a significantly improved performance when burning in free air when compared to wrapping papers H and I, while maintaining very similar TNCO levels to wrapping paper G.

Table 7

A blind smoking conducted with a panel of experts as in example 3 showed that cigarette L was closer in taste to reference cigarette I.