EP4127312B1 - Wrapping paper for smoking articles with improved ash pattern - Google Patents

Description

FIELD OF INVENTION

The invention relates to a wrapping paper for smoking articles which contains cellulose fibres loaded with filler particles which give the paper particularly favourable properties. In particular, the ash of a smoking article made from this wrapping paper has a better appearance.

BACKGROUND AND STATE OF THE ART

A typical smoking article comprises a cylindrical tobacco rod containing an aerosol-forming material, typically tobacco or a tobacco-based material, which is wrapped in a wrapping material. In most cases, the wrapping material comprises a paper, i.e. a sheet-like material containing cellulose fibers. Furthermore, a smoking article can comprise a filter wrapped in a filter wrapping paper and a tipping paper that simultaneously wraps the filter and part of the tobacco rod, thus connecting the filter and the tobacco rod together.

When the smoking article is used, the aerosol-forming material is heated or burned to create an aerosol which flows through the smoking article when the smoking article is used and is inhaled by the consumer.

Particularly when the aerosol-forming material is only heated but not burned, the smoking article may also include components that transmit the aerosol or cool the aerosol, and are typically arranged between the tobacco rod and the filter.

When the tobacco rod is burned or heated to release the aerosol, the wrapping paper of the tobacco rod is thermally degraded. The wrapping paper can discolor and partially lose its mechanical stability, which is why the visual appearance of the smoking article changes. This appearance of a used or in-use smoking article and in particular its tobacco rod is known as the ash image.

From the consumer's point of view, it is a sign of a high quality smoking article if it has a good ash pattern, that is, if the tobacco rod essentially retains its cylindrical shape after burning or heating, of a uniform white color and no dark particles, such as tobacco particles or their ash, protrude through the wrapping material.

Various possibilities are known from the prior art for improving the ash pattern of a smoking article. For example, the basis weight of the wrapping paper can be increased or burning salts such as trisodium citrate or tripotassium citrate can be added or their content can be increased. However, these possibilities have the disadvantage that they increase the proportion of non-tobacco materials in the smoking article and can therefore negatively change the taste of the smoking article. There is therefore an interest in improving the ash pattern of a smoking article without adding new components to the wrapping paper or significantly increasing its mass. This interest exists not only for the wrapping paper that directly wraps the aerosol-forming material, but also generally for wrapping papers of other components of the smoking article, in particular those that can also be exposed to the high temperatures of the aerosol.

DE102004045089 A1 discloses a method for loading a fiber suspension of cellulose fibers with calcium carbonate, which is characterized by the following process steps: introducing calcium hydroxide in liquid or dry form or calcium oxide into the fiber suspension, introducing carbon dioxide into the fiber suspension, precipitating calcium carbonate from the calcium hydroxide by the carbon dioxide in a pressurized pressure vessel.

DE10351292A1 discloses a method for loading a cellulose fiber-containing fiber suspension with calcium carbonate, which comprises the following method steps: introducing calcium hydroxide in liquid or dry form or calcium oxide into the fiber suspension, introducing gaseous carbon dioxide into the fiber suspension, precipitating calcium carbonate by the carbon dioxide, grinding the fiber suspension during the loading process and washing the fiber suspension after the crystallization process and/or before the grinding process and/or during the grinding process and/or after the grinding process.

DE102015105882A1 discloses a wrapping paper for smoking articles with a basis weight of at least 10 g/m ² and at most 70 g/m ² , which comprises a mixture of cellulose fibers, wherein the mixture of cellulose fibers is formed by at least 90% short-fiber cellulose fibers in relation to the mass of the cellulose fibers in the cellulose mixture, or at least 95% short-fiber cellulose fibers in relation to the number of cellulose fibers, wherein at least 10% of the short-fiber cellulose fibers, in relation to the mass of the number of cellulose fibers in the cellulose fiber mixture, are ground, wherein the wrapping paper has an air permeability on more than 50% of its surface, preferably at least 55% of its surface and particularly preferably at least 60% of its surface which is at least 30 cm ³ /(cm ² ·min·kPa), and wherein the wrapping paper contains at least one fire salt.

SUMMARY OF THE INVENTION

In the following, "wrapping paper" shall mean any paper that wraps the smoking article or at least one of its components.

The invention is based on the object of providing a wrapping paper for smoking articles which gives the smoking article a good ash appearance without the mass of the wrapping paper having to be significantly increased or unusual components having to be added to the wrapping paper.

This object is achieved by a wrapping paper for a smoking article according to claim 1, a laminate according to claim 14 and a smoking article according to claim 15 which comprises this wrapping paper. Advantageous further developments are specified in the dependent claims.

The inventor has found that this problem can be solved by the wrapping paper containing cellulose fibers loaded with calcium carbonate particles. Cellulose fibers and calcium carbonate particles are common components of wrapping papers for smoking articles, but in the prior art the calcium carbonate particles are not connected to the cellulose fibers, but are only arranged between the cellulose fibers. Such calcium carbonate particles are referred to as "free calcium carbonate particles" to distinguish them from the calcium carbonate particles with which the cellulose fibers are loaded, i.e. connected. Such cellulose fibers loaded with calcium carbonate particles can be produced, for example, by precipitating the calcium carbonate in the simultaneous presence of the cellulose fibers and by appropriately managing the precipitation process.

Specifically, the wrapping paper according to the invention comprises cellulose fibers loaded with calcium carbonate particles, wherein the mass of the cellulose fibers loaded with calcium carbonate particles is at least 10% of the mass of the wrapping paper and the calcium carbonate particles in the cellulose fibers loaded with calcium carbonate particles make up at least 20% and at most 80% of the mass of the cellulose fibers loaded with calcium carbonate particles.

The inventor assumes that the calcium carbonate particles connected to the pulp fibers form a framework that remains after the thermal degradation of the pulp fibers and thus ensures the stability of the thermally degraded wrapping paper and thus prevents, for example, ash particles of the aerosol-forming material from penetrating the wrapping paper. In this way, the overall ash pattern of the Smoking article. In contrast, the free calcium carbonate particles do not form such framework-like structures and therefore do not contribute to improving the ash pattern to the same extent. Therefore, with a comparable ash pattern, the mass of calcium carbonate particles in the wrapping paper can be reduced by using cellulose fibers loaded with calcium carbonate particles or the overall mass of the wrapping paper can be reduced. This also reduces the influence of the wrapping paper on the taste of the smoking article.

• . Es kann aber auch vorgesehen sein, dass das Umhüllungspapier neben den mit Calciumcarbonatpartikeln beladenen Zellstofffasern auch Zellstofffasern enthält, die nicht mit Calciumcarbonatpartikeln beladen sind. Erfindungsgemäß beträgt der Anteil solcher Zellstofffasern mindestens 20% und höchstens 80% bezogen auf die Masse des Umhüllungspapiers.

The wrapping paper according to the invention offers particular advantages if it has a high level of air permeability. Conventional wrapping paper with a high level of air permeability has more and larger pores and is therefore even less able to form a mechanically stable framework during thermal degradation, which is why the ash formation is often unacceptable. This effect can be largely compensated for by the cellulose fibers loaded with calcium carbonate particles in the wrapping paper according to the invention.

• However, it can also be provided that the wrapping paper contains, in addition to the cellulose fibers loaded with calcium carbonate particles, also cellulose fibers that are not loaded with calcium carbonate particles. According to the invention, the proportion of such cellulose fibers is at least 20% and at most 80% based on the mass of the wrapping paper.

Both the cellulose fibers and the cellulose fibers loaded with calcium carbonate particles can be obtained from softwoods such as spruce, pine or fir, from hardwoods such as eucalyptus, birch or beech, or from other plants such as hemp, flax, jute, sisal, abaca or cotton. The cellulose fibers can also be obtained from regenerated cellulose, such as viscose fibers, modal fibers, Lyocell ^® or Tencel ^® . Mixtures of cellulose fibers from different sources can be used.

The wrapping paper according to the invention contains at least 10% cellulose fibers loaded with calcium carbonate particles. The wrapping paper can be uncoated or coated. The cellulose fibers loaded with calcium carbonate particles can be in the mass of the wrapping paper or in an optional coating on the wrapping paper. If cellulose fibers loaded with calcium carbonate particles are in the mass of the wrapping paper, the proportion of cellulose fibers loaded with calcium carbonate particles is preferably higher and amounts to at least 30% and at most 70%, in each case based on the mass of the wrapping paper.

A high proportion of pulp fibres loaded with calcium carbonate particles allows the proportion of free calcium carbonate particles to be reduced and at the same time the ash formation to be improved. It is even possible that the use of pulp fibres loaded with calcium carbonate particles can reduce the total content of calcium carbonate particles in the wrapping paper. can be reduced without impairing the ash appearance. However, the cellulose fibers loaded with calcium carbonate particles form fewer hydrogen bonds, so that the overall tensile strength of the wrapping paper can decrease. Therefore, the amount of cellulose fibers loaded with calcium carbonate particles in the wrapping paper cannot be chosen to be arbitrarily high, especially if the cellulose fibers are loaded with a large amount of calcium carbonate particles.

Preferably, the cellulose fibers loaded with calcium carbonate particles are obtained from hardwoods such as eucalyptus, birch or beech. These cellulose fibers are generally subjected to less mechanical stress during the production of the wrapping paper, for example during grinding, so that fewer calcium carbonate particles can be lost in the production process.

The calcium carbonate particles of the cellulose fibers loaded with calcium carbonate particles are preferably precipitated calcium carbonate particles and particularly preferably precipitated calcium carbonate particles with a rhombohedral structure. These structures can be produced particularly well in a precipitation process on the cellulose fibers.

The mass of calcium carbonate particles based on the mass of the cellulose fibers loaded with calcium carbonate particles in the wrapping paper according to the invention is preferably at least 20% and at most 60%. In the preferred interval, a particularly favorable compromise is achieved between the desired improvement in the ash pattern and the undesirable reduction in the tensile strength.

The wrapping paper can also contain free fillers that are not bound to the pulp fibers. The proportion of free fillers is preferably at least 1% and at most 40%, particularly preferably at least 5% and at most 35% and very particularly preferably at least 10% and at most 30%, in each case based on the mass of the wrapping paper. These fillers can serve to influence the whiteness, opacity and pore structure of the wrapping paper. However, a high content of free fillers reduces the tensile strength of the wrapping paper. There is also a risk with the free fillers that they settle as dust in further processing steps, for example when making a smoking article from the wrapping paper, and thus shorten the necessary cleaning intervals of the machines. In the preferred intervals, the advantages of using free fillers outweigh the disadvantages.

The free fillers in the wrapping paper are preferably carbonates, oxides, hydroxides and silicates. Particularly preferred fillers are calcium carbonate, magnesium carbonate, magnesium oxide, magnesium hydroxide, aluminum hydroxide, titanium dioxide, talc, kaolin, calcined Kaolin and mixtures thereof. Precipitated calcium carbonate is particularly preferred.

The ratio between the mass of calcium carbonate particles contained in the cellulose fibers loaded with calcium carbonate particles and the mass of free filler particles in the wrapping paper can be important for adjusting the ash image in relation to other properties such as whiteness, opacity and tensile strength. Preferably, the ratio of the mass of calcium carbonate particles contained in the cellulose fibers loaded with calcium carbonate particles and the mass of free filler particles in the wrapping paper is 5:95 to 100:0, particularly preferably it is 10:90 to 80:20 and very particularly preferably it is 10:90 to 50:50.

The wrapping paper can also contain burn salts. The burn salts influence the speed of the thermal degradation of the wrapping paper and can also help to improve the ash pattern because they act partly as an adhesive or as a sintering aid between the free filler particles and thus improve the mechanical stability of the thermally degraded wrapping paper. Burn salts are preferably used in the wrapping paper that wraps the tobacco rod.

The proportion of fire salts in the wrapping paper can be selected variably, whereby the proportion is preferably at least 0.3% and at most 7%, particularly preferably at least 0.5% and at most 5% and very particularly preferably at least 0.5% and at most 3%, in each case based on the mass of the wrapping paper.

The burn salts can preferably be selected from the group consisting of citrates, malates, tartrates, acetates, nitrates, succinates, fumarates, gluconates, glycolates, lactates, oxylates, salicylates, α-hydroxycaprylates, phosphates, chlorides and hydrogen carbonates, and mixtures thereof and particularly preferably from the group consisting of trisodium citrate, tripotassium citrate and mixtures thereof.

In one embodiment of the wrapping paper, the wrapping paper is provided essentially over its entire surface with a coating that contains free calcium carbonate particles and/or cellulose fibers loaded with calcium carbonate particles. "Essentially coated over the entire surface" means that a full-surface coating is intended or at least 95% of the surface is coated. A suitably selected coating can further improve the ash pattern without adding unusual components to the wrapping paper. The coating increases the content of calcium carbonate particles on the paper surface, so that a stable framework can be formed more easily, which ensures the mechanical stability of the wrapping paper after its thermal degradation.

The coating can be carried out by applying a composition by means of methods known from the prior art, such as in a size press or a film press of a paper machine, in coating or coating units or by means of a printing machine, in particular a gravure printing machine.

A composition suitable for producing the coating comprises a solvent, preferably water, and calcium carbonate particles or cellulose fibers loaded with calcium carbonate particles. Calcium carbonate particles that are not part of the calcium carbonate particles of the loaded cellulose fibers are referred to as free calcium carbonate particles, as in the wrapping paper itself. The proportion of free calcium carbonate particles in the composition can preferably be at least 0% and at most 40%, particularly preferably at least 5% and at most 30%, in each case based on the mass of the composition. The proportion of cellulose fibers loaded with calcium carbonate particles can preferably be at least 0% and at most 10%, particularly preferably at least 1% and at most 7%, in each case based on the mass of the composition. It should be noted that the above-mentioned coating corresponds to the applied composition in the dried state, i.e. when the solvent in particular has evaporated.

If the composition contains free calcium carbonate particles, the composition should contain a binder to fix the free calcium carbonate particles to the wrapping paper. This binder then also remains in the coating formed by applying the composition. If the composition contains calcium carbonate particles only in the form of cellulose fibers loaded with them, a binder is not absolutely necessary, but is also preferable for better fixation. The binder is particularly preferably selected from the group consisting of starch, starch derivatives, carboxymethylcellulose, cellulose derivatives, polyvinyl alcohol, galactomannan, gum arabic, alginates and mixtures thereof. The starch is very particularly preferably a mechanically fragmented and chemically cross-linked starch because it is not chemically soluble in water and therefore penetrates the paper structure less and thus reduces the air permeability of the wrapping paper less. The skilled person can choose the amount of binder from experience, particularly with regard to the requirements of the application process.

The composition may comprise further components which the person skilled in the art can suitably select, including, for example, fire salts, dyes, flavourings, humectants such as glycerol or propylene glycol, or substances for influencing the viscosity.

The composition can be applied to one or both sides of the wrapping paper, but preferably the composition is applied to the side that is the smoking article made from it. This side is generally already known during the manufacture of the wrapping paper and in most cases is the side facing away from the paper machine screen. The composition is therefore preferably applied to the side of the wrapping paper facing away from the paper machine screen, which is also referred to as the top side.

After drying of the applied composition, the basis weight of the coating is preferably at least 0.5 g/m ² and at most 10 g/m ² , particularly preferably at least 1 g/m ² and at most 5 g/m ² .

In a preferred embodiment, the mass of the free calcium carbonate particles and the calcium carbonate particles of the loaded pulp fibers in the coating together amounts to at least 1% and at most 20%, particularly preferably at least 2% and at most 15% of the mass of the coated wrapping paper. The wrapping paper preferably additionally contains pulp fibers loaded with calcium carbonate particles in the mass, the mass of the pulp fibers loaded with calcium carbonate particles in the wrapping paper without the coating preferably being at least 1% and at most 70%, particularly preferably at least 1% and at most 60% of the mass of the wrapping paper, and the calcium carbonate particles in the pulp fibers loaded with calcium carbonate particles make up at least 10% and at most 60% of the mass of the pulp fibers loaded with calcium carbonate particles.

In a preferred embodiment, the wrapping paper according to the invention can also be part of a laminate, particularly preferably a laminate with another material with a thermal conductivity that exceeds that of the wrapping paper by a factor of at least two, preferably at least four. In particularly preferred embodiments, the other material of the laminate is formed by an aluminum foil. Such laminates can be used above all in smoking articles in which the aerosol-forming material is only heated but not burned, in order to prevent the smoking article from being lit and smoked like a normal cigarette.

In a further preferred embodiment of the wrapping paper for a smoking article, the smoking article is a cigarette and the wrapping paper additionally has patterns or structures, particularly preferably bands printed in the circumferential direction, in order to reduce the tendency of the smoking article to ignite measured according to ISO 12863:2010.

The basis weight of the wrapping paper according to the invention is preferably at least 15 g/m ² and at most 150 g/m ² , particularly preferably at least 20 g/m ² and at most 120 g/m ² , very particularly preferably at least 20 g/m ² and at most 40 g/m ² . The The basis weight of the wrapping paper can be determined according to ISO 536:2019, whereby a coating, if present, counts towards the basis weight.

The thickness of the wrapping paper according to the invention is preferably at least 10 µm and at most 200 µm, preferably at least 15 µm and at most 120 µm and very particularly preferably at least 30 µm and at most 100 µm. The thickness can be determined according to ISO 534:2011 on a single layer of the wrapping paper. Here too, a coating, if present, counts towards the thickness of the wrapping paper.

The mechanical properties of the wrapping paper according to the invention can be important for the manufacture of a smoking article from this wrapping paper. The essential mechanical properties include tensile strength, elongation at break and energy absorption capacity, all of which can be determined according to ISO 1924-2:2008.

The tensile strength of the wrapping paper is preferably at least 7 N/15 mm, particularly preferably at least 8 N/15 mm and very particularly preferably at least 10 N/15 mm. Since the material and energy expenditure in paper production to increase the tensile strength is high, it is advantageous if the tensile strength is at most 100 N/15 mm, preferably at most 80 N/15 mm and particularly preferably at most 70 N/15 mm. The tensile strength can be increased primarily by increasing the basis weight and increasing the proportion of cellulose fibers, as well as by more intensive grinding of the cellulose fibers.

In order to compensate for differences in speed in the machines for producing smoking articles from the wrapping paper, it is advantageous if the wrapping paper has a certain degree of stretchability. The breaking elongation of the wrapping paper according to the invention is preferably at least 0.9% and at most 3%, particularly preferably at least 1% and at most 2%.

Another mechanical parameter that is important for the processability of the wrapping paper into a smoking article is the energy absorption capacity. The energy absorption capacity describes how much energy is required to tear the paper. For the wrapping paper according to the invention, it is preferred if the energy absorption capacity is at least 3 J/m ² and at most 50 J/m ² and very particularly preferably at least 3.5 J/m ² and at most 35 J/m ² .

The whiteness (ISO brightness) of the wrapping paper can be important for its optical appearance and also for the ash pattern. It is measured according to ISO 2470-1:2016. In general, white wrapping papers are preferred for optical reasons, so that the whiteness of the wrapping paper according to the invention is at least 80% and particularly preferably at least 90%.

The whiteness can be influenced, for example, by the choice of free fillers; in particular, the whiteness can be significantly increased with titanium dioxide.

The opacity of the wrapping paper is also important for the visual appearance. A high opacity is generally beneficial because components of the smoking article are then not visible through the wrapping paper. The opacity is measured according to ISO 2471:2008. Preferably, the opacity of the wrapping paper is at least 70% and particularly preferably at least 80%. The opacity can also be increased by increasing the amount of free fillers in the wrapping paper.

In certain applications of the wrapping paper according to the invention on a smoking article, its air permeability is important. In such applications, for example, when the smoking article is used, air should flow through the wrapping paper into the smoking article in order to dilute the aerosol. The air permeability can be measured according to ISO 2965:2019.

In conventional wrapping papers, those with high air permeability generally have a poor ash image, so that in this case the invention can be used particularly advantageously if the content of calcium carbonate particles associated with the pulp fibers is increased. According to the invention, the wrapping paper comprises pulp fibers loaded with calcium carbonate particles, wherein the mass of the pulp fibers loaded with calcium carbonate particles is at least 10% of the mass of the wrapping paper and the calcium carbonate particles in the pulp fibers loaded with calcium carbonate particles make up at least 20% and at most 80% of the mass of the pulp fibers loaded with calcium carbonate particles and the wrapping paper has an air permeability according to ISO 2965:2019 of at least 50 cm ³ /(cm ² ·min·kPa) and at most 300 cm ³ /(cm ² ·min·kPa).

The above-mentioned preferred and particularly preferred intervals for the type and amount of pulp fibers, the type and amount of pulp fibers loaded with calcium carbonate particles, the proportion of calcium carbonate particles in the pulp fibers loaded with calcium carbonate particles, the type and amount of free fillers, the type and amount of fire salts, as well as the mechanical parameters such as tensile strength, elongation at break and energy absorption capacity and the optical parameters such as whiteness and opacity also apply to this particular embodiment. A coating, on the other hand, is not preferred for this particular embodiment because it can reduce air permeability too much.

A smoking article according to the invention comprises an aerosol-forming material and the wrapping paper according to the invention. In a preferred embodiment of the smoking article the aerosol-forming material comprises tobacco and said wrapping paper envelops the aerosol-forming material.

In a further preferred embodiment, the smoking article is a smoking article according to the invention in which the aerosol-forming material is only heated but not burned.

In a particularly preferred embodiment, the smoking article is a cigarette and the wrapping paper is a cigarette paper.

Both the wrapping paper according to the invention and the smoking article according to the invention can be produced using methods known per se in the prior art.

SHORT DESCRIPTION OF THE CHARACTERS

Fig.1

shows an example of an electron micrograph of pulp fibers loaded with coarse calcium carbonate particles, whereby the calcium carbonate particles make up about 20% of the mass of the pulp fibers loaded with calcium carbonate particles.

Fig.2

shows an example of an electron micrograph of pulp fibers loaded with fine calcium carbonate particles, whereby the calcium carbonate particles make up about 20% of the mass of the pulp fibers loaded with calcium carbonate particles.

Fig. 3

shows the ash pattern of three filter cigarettes made from a wrapping paper not according to the invention.

Fig.4

shows the ash pattern of three filter cigarettes made from a wrapping paper according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following, some preferred embodiments of wrapping papers according to the invention are described and compared with a wrapping paper not according to the invention.

The non-inventive wrapping paper used as a reference had a basis weight of 32.6 g/m ² and was made from 28% softwood pulp fibers and 42% hardwood pulp fibers as well as 30% free calcium carbonate particles, the percentages referring to the mass of the wrapping paper. Further properties of the wrapping paper can be seen in Table 1 in the "REF" line.

A total of 14 wrapping papers according to the invention, designated A to K and X to Z, were produced, the composition of the wrapping papers being given in Table 1. In Table 1, "SW" in % means the proportion of pulp fibers from softwoods, "HW" in % the proportion of pulp fibers from hardwoods, "CF" in % the proportion of pulp fibers loaded with calcium carbonate particles and "FI" in % the proportion of free fillers. The percentages are based on the mass of the wrapping paper.

The pulp fibers from softwood and hardwood are standard products available on the market. The pulp fibers loaded with calcium carbonate particles were purchased from Schaefer Kalk. All of the free filler was formed from precipitated calcium carbonate particles.

Furthermore, in Table 1 under "CCP" the mass of calcium carbonate particles in the pulp fibers loaded with calcium carbonate particles is given in %, based on the mass of the pulp fibers loaded with calcium carbonate particles. The size of these particles is also given as "fine" or "coarse". In this context, Figure 1 an electron micrograph of pulp fibres loaded with coarse calcium carbonate particles and Figure 2 shows an electron micrograph of pulp fibers loaded with fine calcium carbonate particles, both of which were used to produce some wrapping papers according to the invention. The mass fraction of calcium carbonate particles in the pulp fibers loaded with calcium carbonate particles from Figures 1 and 2 was about 17.3%. The pulp fibers were formed by pulp fibers from eucalyptus.

Wrapping paper X was identical to wrapping paper REF and wrapping papers Y and Z were identical to wrapping paper G. Wrapping paper Y was fully coated with a composition of 89% water, 5.5% mechanically fragmented and chemically cross-linked starch and 5.5% free calcium carbonate particles, with the percentages referring to the mass of the composition. Wrapping papers X and Z were fully coated with a composition of 95.5% water, 1% mechanically fragmented and chemically cross-linked starch and 3.5% calcium carbonate particles. loaded fibers, whereby the percentages refer to the mass of the composition. After application and drying of the composition, a mass of approximately 2 g/m ² remained on the wrapping papers.

The mechanically fragmented, chemically cross-linked starch can be obtained, for example, from the company Emsland-Stärke GmbH. Table 1 Paper CCP Size CF SW HW FI % % % % % REF 0 28 42 30 A 25.3 fine 42 28 0 30 B 25.3 fine 36 24 0 40 C 17.3 rough 21 28 21 30 D 17.3 rough 18 24 18 40 E 17.3 rough 42 28 0 30 F 17.3 rough 36 24 0 40 G 25.5 rough 42 28 0 30 H 25.5 rough 36 24 0 40 I 33.7 rough 21 28 21 30 J 33.7 rough 42 28 0 30 K 33.7 rough 36 24 0 40 X 0 28 42 30 Y 25.5 rough 42 28 0 30 Z 25.5 rough 42 28 0 30

The properties of the non-inventive wrapping paper REF and the inventive wrapping papers A to K and X to Z were determined and are given in Table 2, where "BW" means the basis weight, "EL" the elongation at break and "AP" the air permeability. Table 2 Paper BW thickness tensile strenght EL TEA white opacity AP g/ ^m2 µm N/15mm % J/m ² % % cm ³ /(cm ² ·min·kPa) REF 32.6 63 12.3 1.6 9.5 93 82 47 A 29.6 64 7.2 1.1 3.9 92 78 81 B 34.3 65 8.3 1.0 3.9 93 81 71 C 29.9 63 10.8 1.4 7.5 93 78 105 D 30.4 64 6.3 1.1 3.4 93 83 135 E 30.5 66 9.4 1.5 6.6 93 81 102 F 31.1 66 8.1 1.3 4.8 93 83 100 G 33.2 69 11.2 1.6 8.4 93 82 105 H 31.1 66 8.7 1.4 5.7 93 82 123 I 30.0 65 8.9 1.4 5.7 93 80 132 J 32.8 68 11.5 1.5 8.1 93 81 90 K 30.8 64 8.5 1.3 5.4 93 82 130 X 34.6 67 16.9 1.4 10.9 92 83 42 Y 35.3 70 16.3 1.4 10.7 93 84 83 Z 35.0 71 16.8 1.3 11.0 93 85 80

Smoking articles in the form of filter cigarettes with a diameter of approximately 7.8 mm and a length of 83 mm were produced from the non-inventive wrapping paper REF and the inventive wrapping papers A to K and X to Z. The tobacco used was an American blend and the wrapping papers wrapped the tobacco in each case. The ash pattern of these smoking articles was evaluated using an image analysis method. Three cigarettes of each cigarette were lit in a vertical position and the tobacco was waited for to completely smolder. A digital image of each cigarette was then taken against a neutral background under constant lighting conditions. Image analysis software then determined the proportion of non-white areas in the area of the smoldered tobacco rod. The proportion of these non-white areas in relation to the total area of the smoldered tobacco rod is expressed as a percentage and referred to as the " Ash Index ", with an average value being calculated from the images of three cigarettes in each case. The higher the percentage, the more non-white areas the smoldering tobacco rod contains and the worse the consumer judges the ash appearance.

The Ash Index thus measured is given in Table 3. Table 3 Paper Ash Index % REF 11.1 A 9.5 B 8.6 C 7.6 D 4.8 E 7.7 F 5.8 G 6.5 H 8.2 I 7.0 J 7.5 K 5.1 X 8.5 Y 4.3 Z 4.5

Figure 3 shows the ash pattern of three filter cigarettes made from the non-inventive wrapping paper REF. Figure 4 shows the ash image of three filter cigarettes that were made from the wrapping paper K according to the invention. Even without quantifying the ash image by image analysis, the difference is already clearly visible.

The purpose of the wrapping papers A to K according to the invention was to achieve properties that were as similar as possible to the non-inventive wrapping paper REF in order to be able to clearly demonstrate the positive effect of the cellulose fibers loaded with calcium carbonate particles. The examples are therefore not to be understood as a limitation of the invention and the person skilled in the art is able to produce wrapping papers according to the invention with, for example, a different composition, a different basis weight, a different thickness, a different air permeability or other mechanical or optical properties in the claimed range.

From Table 3 it can be seen that the Ash Index of cigarettes with wrapping papers A to K is always lower than that of cigarettes with the non-inventive wrapping paper REF. This means that the wrapping papers A to K lead to a better ash appearance.

From Table 2 it can be seen that, as was intended when producing the wrapping papers, the wrapping papers A to K according to the invention are very similar to the non-inventive wrapping paper REF in terms of basis weight, thickness, elongation at break, whiteness and opacity. The tensile strength and thus also the energy absorption capacity of the wrapping papers A to K are somewhat lower than for the non-inventive wrapping paper REF. This is caused by the cellulose fibers loaded with calcium carbonate particles, since the calcium carbonate particles on the cellulose fibers hinder the formation of hydrogen bonds between the cellulose fibers and thus reduce the tensile strength of the wrapping paper.

It is important that the air permeability of the wrapping papers A to K is higher than that of the wrapping paper not according to the invention. Despite this higher air permeability, the cigarettes made from the wrapping papers A to K have a better ash pattern than the cigarettes made from the wrapping paper REF. This shows that with high air permeability, the use of cellulose fibers loaded with calcium carbonate particles offers a very special advantage.

If necessary, the specialist can of course reduce the air permeability of the wrapping papers A to K, for example by grinding the pulp fibers more intensively, and thus set the same value as for the wrapping paper REF. It is to be expected that the Ash Index will then fall even further and the ash pattern will thus improve even further.

A comparison between the wrapping paper I ( Ash Index 7.0), which contains a total of about 36% free calcium carbonate particles bound to cellulose fibers, and the non-inventive wrapping paper REF ( Ash Index 11.1), which contains 40% exclusively free calcium carbonate particles, shows that the ash pattern can be improved despite a lower total content of calcium carbonate particles.

The coated wrapping papers X, Y and Z all show an improvement in the ash image. The papers X to Z also all have a higher tensile strength than the non-inventive wrapping paper REF and than the uncoated, inventive wrapping papers A to K, which is a further advantage of these embodiments.

Overall, it can be seen that a significant improvement in the ash pattern can be achieved with the wrapping papers according to the invention without negatively affecting the other properties of the wrapping paper and without significantly increasing the mass of the wrapping paper or adding unusual components to the wrapping paper.

Claims (15)

1. Wrapper paper for smoking articles, which comprises pulp fibers loaded with calcium carbonate particles, wherein the mass of the pulp fibers loaded with calcium carbonate particles is at least 10% of the mass of the wrapper paper and the calcium carbonate particles in the pulp fibers loaded with calcium carbonate particles make up at least 20% and at most 80% of the mass of the pulp fibers loaded with calcium carbonate particles and the wrapper paper has an air permeability in accordance with ISO 2965:2019 of at least 50 cm³/(cm²·min·kPa) and at most 300 cm³/(cm²·min·kPa).
2. Wrapper paper according to claim 1 which, in addition to the pulp fibers loaded with calcium carbonate particles, also contains pulp fibers which are not loaded with calcium carbonate particles and their proportion is at least 1% and at most 95%, preferably at least 10% and at most 80% and in particular at least 20% and at most 70%, each with respect to the mass of the wrapper paper.
3. Wrapper paper according to claim 1 or 2, wherein the pulp fibers loaded with calcium carbonate particles and, if present, also the pulp fibers not loaded with calcium carbonate particles, are at least partially sourced from a coniferous wood, in particular spruce, pine or fir, from a deciduous wood, in particular eucalyptus, birch or beech, or from hemp, flax, sisal, abaca or cotton, and/or
   wherein the pulp fibers loaded with calcium carbonate particles and, if present, also the pulp fibers not loaded with calcium carbonate particles, are at least partially sourced from regenerated cellulose, and are in particular formed by viscose fibers, modal fibers, Lyocell^® or Tencel^®.
4. Wrapper paper according to one of the preceding claims, wherein the pulp fibers loaded with calcium carbonate particles are at least partially located in the bulk of the wrapper paper, wherein the proportion of pulp fibers loaded with calcium carbonate particles is preferably at least 5% and at most 80% and particularly preferably at least 30% and at most 70%, each with respect to the mass of the wrapper paper, and/or
   which has a coating and wherein the pulp fibers loaded with calcium carbonate particles are at least partially located in the coating, wherein their proportion, in the case in which the pulp fibers loaded with calcium carbonate particles are exclusively located in the coating, is at least 1% and at most 30%, preferably at least 2% and at most 25%, each with respect to the mass of the wrapper paper.
5. Wrapper paper according to one of the preceding claims, wherein the calcium carbonate particles of the pulp fibers loaded with calcium carbonate particles are formed by precipitated calcium carbonate particles, in particular by precipitated calcium carbonate particles with a rhombohedral structure, and/or
   wherein the mass of the calcium carbonate particles with respect to the mass of the pulp fibers loaded with calcium carbonate particles is at least 10% and at most 70%, preferably at least 20% and at most 60%.
6. Wrapper paper according to one of the preceding claims, which further contains free filler materials that are not bonded to the pulp fibers, wherein the proportion of free filler materials is preferably at least 1% and at most 40%, particularly preferably at least 5% and at most 35% and in particular at least 10% and at most 30%, each with respect to the mass of the wrapper paper.
7. Wrapper paper according to claim 6, wherein the free filler materials are formed by carbonates, oxides, hydroxides and silicates or combinations thereof and, in particular by calcium carbonate, preferably precipitated calcium carbonate, magnesium carbonate, magnesium oxide, magnesium hydroxide, aluminum hydroxide, titanium dioxide, talcum, kaolin, calcinated kaolin and mixtures thereof, and/or
   wherein the ratio of the mass of calcium carbonate particles that are contained in the pulp fibers loaded with calcium carbonate particles and the mass of free filler material particles in the wrapper paper is 5:95 to 100:0, preferably 10:90 to 80:20 and more particularly preferably 10:90 to 50:50.
8. Wrapper paper according to one of the preceding claims, which further contains burn additives the proportion of which is preferably at least 0.3% and at most 7%, particularly preferably at least 0.5% and at most 5% and in particular at least 0.5% and at most 3%, each with respect to the mass of the wrapper paper, wherein
   the burn additives preferably are selected from the group consisting of citrates, malates, tartrates, acetates, nitrates, succinates, fumarates, gluconates, glycolates, lactates, oxalates, salicylates, α-hydroxycaprylates, phosphates, chlorides and hydrogen carbonates, and mixtures thereof, and are particularly preferably selected from the group consisting of trisodium citrate, tripotassium citrate and mixtures thereof.
9. Wrapper paper according to one of the preceding claims, wherein at least 95% of its surface has a coating which contains free calcium carbonate particles and/or pulp fibers loaded with calcium carbonate particles,

   wherein the coating preferably further comprises a binder that is suitable for binding the free calcium carbonate particles or the pulp fibers loaded with calcium carbonate particles to the wrapper paper, wherein the binder is preferably selected from the group consisting of starch, in particular mechanically fragmented and chemically cross-linked starch, starch derivatives, carboxymethyl cellulose, cellulose derivatives, polyvinyl alcohol, galactomannan, gum Arabic, alginates and mixtures thereof, and/or

   wherein the coating preferably comprises further components selected from the group consisting of burn additives, colorants, flavors, humectants, in particular glycerol or propylene glycol, or substances for adjusting the viscosity, and/or

   wherein the coating preferably is located on that side of the wrapper paper that faces the outside of the smoking article to be manufactured therefrom and/or

   wherein the mass per unit area of the coating is at least 0.5 g/m² and at most 10 g/m², particularly preferably at least 1 g/m² and at most 5 g/m².
10. Wrapper paper according to claim 9, wherein in the coating, the mass of free calcium carbonate particles and of calcium carbonate particles of the loaded pulp fibers in the coating taken together is at least 1% and at most 20%, particularly preferably at least 2% and at most 15% of the mass of the coated wrapper paper, wherein the
    wrapper paper preferably additionally contains pulp fibers loaded with calcium carbonate particles in the bulk, wherein the mass of the pulp fibers loaded with calcium carbonate particles in the wrapper paper without the coating is preferably at least 1% and at most 60% of the mass of the wrapper paper and the calcium carbonate particles in the pulp fibers loaded with calcium carbonate particles make up at least 10% and at most 60% of the mass of the pulp fibers loaded with calcium carbonate particles.
11. Wrapper paper according to one of the preceding claims, wherein the wrapper paper is intended for a cigarette and the wrapper paper has patterns or structures, preferably bands printed in the circumferential direction, to reduce the ignition propensity of the smoking article measured in accordance with ISO 12863:2010, and/or

    with a basis weight of at least 15 g/m² and at most 150 g/m², preferably at least 20 g/m² and at most 120 g/m² and particularly preferably at least 20 g/m² and at most 40 g/m², wherein a coating, if present, counts towards the basis weight of the wrapper paper, and/or

    with a thickness of at least 10 µm and at most 200 µm, preferably at least 15 µm and at most 120 µm and particularly preferably at least 30 µm and at most 100 µm, wherein the coating, if present, counts towards the thickness of the wrapper paper.
12. Wrapper paper according to one of the preceding claims, with a tensile strength of at least 7 N/15 mm, preferably at least 8 N/15 mm and particularly preferably at least 10 N/15 mm, and/or

    with a tensile strength of at most 100 N/15 mm, preferably at most 80 N/15 mm and particularly preferably at most 70 N/15 mm, and/or

    with a elongation at break of at least 0.9% and at most 3%, particularly preferably at least 1% and at most 2%, and/or

    with a tensile energy absorption of at least 3 J/m² and at most 50 J/m², preferably at least 3.5 J/m² and at most 35 J/m².
13. Wrapper paper according to one of the preceding claims, with a brightness in accordance with ISO 2470-1:2016 of at least 80% and particularly preferably at least 90%, and/or

    with an opacity in accordance with ISO 2471:2008 of at least 70% and particularly preferably at least 80%, and/or

    with an air permeability in accordance with ISO 2965:2019 of at least 0 cm³/(cm²·min·kPa) and at most 300 cm³/(cm²·min·kPa), preferably at least 10 cm³/(cm²·min·kPa) and at most 250 cm³/(cm²·min·kPa) and particularly preferably at least 20 cm³/(cm²·min·kPa) and at most 150 cm³/(cm²·min·kPa).
14. Laminate comprising a wrapper paper according to one of the preceding claims and a further material the thermal conductivity of which exceeds the thermal conductivity of the wrapper paper by a factor of at least two, preferably of at least four, wherein the further material is preferably formed by an aluminum foil.
15. Smoking article comprising an aerosol-forming material and a wrapper paper according to one of claims 1 to 13,
    wherein the aerosol-forming material preferably comprises tobacco, wherein the smoking article is preferably a cigarette and the wrapper paper is a cigarette paper, or in which, during its intended use, the aerosol-forming material is preferably only heated but not burnt.

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