ES2983746T3 - Wrapping paper for smoking articles with improved ash appearance - Google Patents

Abstract

The invention relates to a wrapping paper for smoking articles, comprising cellulose fibres loaded with calcium carbonate particles, wherein the mass of the cellulose fibres loaded with calcium carbonate particles is at least 1% of the mass of the wrapping paper, and the calcium carbonate particles in the cellulose fibres loaded with calcium carbonate particles constitute at least 5% and not more than 80% of the mass of the cellulose fibres loaded with calcium carbonate particles. (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

Wrapping paper for smoking articles with improved ash appearance

Field of invention

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

Background and state of the art

A conventional smoking article comprises a cylindrical tobacco column containing an aerosol-forming material, typically tobacco or a tobacco-based material, wrapped in a wrapping material. In most cases, the wrapping material comprises a paper, i.e. a web-like material containing cellulose fibers. Furthermore, a smoking article may comprise a filter wrapped in a filter wrapping paper and a mouthpiece covering paper that simultaneously wraps around the filter and a portion of the tobacco column, thereby joining the filter and the tobacco column.

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

In particular, if the aerosol-forming material is only heated but not burned, the smoking article may also comprise aerosol-transmitting or aerosol-cooling components, which are typically arranged between the tobacco column and the filter.

When the tobacco column is burned or heated to release the aerosol, the wrapping paper is thermally degraded. This can cause the wrapping paper to discolour and lose some of its mechanical stability, thereby changing the visual appearance of the smoking article. This appearance of a used or in-use smoking article and in particular of its tobacco column is called the ash appearance.

From the consumer's point of view, having a good ash appearance is a sign of the high quality of the smoking article, i.e. if the tobacco column essentially retains its cylindrical shape after burning or heating, is of a uniform white colour and no dark particles, for example tobacco particles or its ash, protrude through the wrapping material.

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

Document DE102004045089 A1 discloses a process for charging a fibrous material suspension of cellulose fibres with calcium carbonate, characterised by the following process steps: Introducing calcium hydroxide in liquid or dry form or calcium oxide into the fibrous material suspension, introducing carbon dioxide into the fibrous material suspension, precipitating calcium carbonate from the calcium hydroxide by means of the carbon dioxide in a pressurised pressure vessel.

Document DE10351292A1 discloses a process for charging a suspension of fibrous material containing cellulose fibres with calcium carbonate, having the following process steps: introducing calcium hydroxide in liquid or dry form or calcium oxide into the suspension of fibrous material, introducing gaseous carbon dioxide into the suspension of fibrous material, precipitating calcium carbonate by the carbon dioxide, grinding the suspension of fibrous material during the charging process and washing the suspension of fibrous material after the crystallisation 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 grammage of at least 10 g/m2 and at most 70 g/m2, comprising a mixture of cellulose fibres, wherein the cellulose fibre mixture is formed at least 90 % by short-staple cellulose fibres in terms of the mass of the cellulose fibres of the cellulose mixture, or at least 95 % by short-staple cellulose fibres with respect to the number of cellulose fibres, wherein at least 10 % of the short-staple cellulose fibres, with respect to the mass of the number of cellulose fibres of the cellulose fibre mixture, are ground, wherein the wrapping paper has an air permeability of at least 30 cm3/(cm2 minkPa) over more than 50 % of its surface, preferably over at least 55 % of its surface and particularly preferably over at least 60 % of its surface. from its surface, and where the wrapping paper contains at least one combustion salt.

Summary of the invention

Hereinafter, "wrapping paper" means any paper used to wrap the smoking article or at least one of its components.

The invention is based on the objective of providing a wrapping paper for smoking articles which gives the smoking article a good ashy appearance without it being necessary to significantly increase the mass of the wrapping paper or to add unusual components to the wrapping paper.

This object is solved 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 comprising this wrapping paper. Advantageous improvements are indicated in the dependent claims.

The inventor has discovered that this objective can be solved by the wrapping paper containing cellulose fibres loaded with calcium carbonate particles. Cellulose fibres and calcium carbonate particles are common components of wrapping papers for smoking articles, but in the prior art the calcium carbonate particles are not bound to the cellulose fibres, but are merely arranged between the cellulose fibres. These calcium carbonate particles are called "free calcium carbonate particles" to distinguish them from the calcium carbonate particles with which the cellulose fibres are loaded, i.e. bound. Such cellulose fibres loaded with calcium carbonate particles can be produced, for example, by precipitation of calcium carbonate in the simultaneous presence of the cellulose fibres with suitable control of 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 constitute 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 bound to the cellulose fibres form a framework which is maintained after thermal degradation of the cellulose fibres and thus ensures the stability of the thermally degraded wrapping paper and prevents, for example, ash particles from the aerosol-forming material from penetrating into the wrapping paper. The overall ashy appearance of the smoking article is thus improved.

In contrast, free calcium carbonate particles do not form such scaffold-like structures and therefore do not contribute to the same extent to improving the ash appearance. Therefore, the mass of calcium carbonate particles in the wrapping paper can be reduced or the total mass of the wrapping paper can be reduced by using cellulose fibres loaded with calcium carbonate particles with a comparable ash appearance. This also reduces the influence of the wrapping paper on the flavour of the smoking article.

The wrapping paper according to the invention offers particular advantages if it has a high air permeability. A conventional wrapping paper with high air permeability has more and larger pores, which makes it even more difficult for it to form a mechanically stable framework during thermal degradation, which is why the ash appearance is often not acceptable. This effect can be largely compensated by the cellulose fibres loaded with calcium carbonate particles in the wrapping paper according to the invention.

However, it is also possible for the wrapping paper to contain cellulose fibres which are not loaded with calcium carbonate particles, in addition to the cellulose fibres loaded with calcium carbonate particles. According to the invention, the proportion of such cellulose fibres is at least 20% and at most 80% with respect to the mass of the wrapping paper.

Both cellulose fibres and cellulose fibres 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. Cellulose fibres can also be obtained from regenerated cellulose, such as viscose fibres, modal fibres, Lyocell® or Tencel®. Blends of cellulose fibres from different origins can be used.

The wrapping paper according to the invention contains at least 10% of cellulose fibres loaded with calcium carbonate particles. The wrapping paper may or may not be coated. The cellulose fibres loaded with calcium carbonate particles in this case may be present in the mass of the wrapping paper or in an optional coating on the wrapping paper. If cellulose fibres loaded with calcium carbonate particles are present in the mass of the wrapping paper, the proportion of cellulose fibres loaded with calcium carbonate particles is preferably higher and is at least 30% and at most 70%, in each case based on the mass of the wrapping paper.

A high proportion of cellulose fibres loaded with calcium carbonate particles makes it possible to reduce the proportion of free calcium carbonate particles and at the same time improve the ash appearance. It is even possible that by using cellulose fibres loaded with calcium carbonate particles, the total content of calcium carbonate particles in the wrapping paper can be reduced without impairing the ash appearance. However, cellulose fibres loaded with calcium carbonate particles form fewer hydrogen bonds, so that the tensile strength of the wrapping paper as a whole may decrease. Therefore, the amount of cellulose fibres loaded with calcium carbonate particles in the wrapping paper cannot be chosen to be arbitrarily high, especially if the cellulose fibres are loaded with a large amount of calcium carbonate particles.

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

The calcium carbonate particles of the calcium carbonate-filled cellulose fibres are preferably precipitated calcium carbonate particles and, particularly preferably, precipitated calcium carbonate particles with a rhombohedral structure. These structures can be generated particularly well on the cellulose fibres in a precipitation process.

The mass of calcium carbonate particles relative to the mass of cellulose fibres filled with calcium carbonate particles in the wrapping paper according to the invention is preferably at least 20% and at most 60%. In the preferred range, there is a particularly favourable compromise between the desired improvement of the ash appearance and the undesirable reduction of the tensile strength.

The wrapping paper may also contain free fillers which are not bound to the cellulose fibres. 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 that free fillers will be deposited in dust form in subsequent processing processes, for example during the production of a smoking article from the wrapping paper, thus shortening the necessary cleaning intervals of the machines. In the preferred intervals, the advantages of using free fillers predominate.

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

The ratio of the mass of calcium carbonate particles contained in the calcium carbonate-filled cellulose fibres to the mass of free filler particles in the wrapping paper can be important for adjusting the ash appearance in relation to other properties such as brightness, opacity and tensile strength. Preferably, the ratio of the mass of calcium carbonate particles contained in the calcium carbonate-filled cellulose fibres to the mass of free filler particles in the wrapping paper is from 5:95 to 100:0, particularly preferably from 10:90 to 80:20 and very particularly preferably from 10:90 to 50:50.

The wrapping paper may also contain flue salts. Flue salts influence the rate of thermal degradation of the wrapping paper and can also contribute to improving the ash appearance, as they act in part as an adhesive or sintering aid between the free filler particles and thus improve the mechanical stability of the thermally degraded wrapping paper. Flue salts are preferably used in the wrapping paper that covers the tobacco column.

The proportion of combustion 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 combustion salts may preferably be selected from the group consisting of citrates, malates, tartrates, acetates, nitrates, succinates, fumarates, gluconates, glycolates, lactates, oxylates, salicylates, a-hydroxycaprylates, phosphates, chlorides and hydrogen carbonates, and mixtures thereof, and especially 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 substantially over its entire surface with a coating containing free calcium carbonate particles and/or cellulose fibers loaded with calcium carbonate particles. In this regard, "substantially over the entire surface" means that a coating of the entire surface is intended or that at least 95% of the surface is coated. A suitably selected coating can further improve the ash appearance without adding unusual components to the wrapping paper. The coating increases the content of calcium carbonate particles on the surface of the paper, facilitating the formation of a stable framework that ensures the mechanical stability of the wrapping paper after thermal degradation.

The coating can be carried out by applying a composition by methods known in the state of the art, such as in a sizing press or a film press of a paper machine, in coating or coating units or by means of a printing machine, in particular an offset printing machine.

A composition suitable for producing the coating comprises a solvent, preferably water, and calcium carbonate particles or cellulose fibres loaded with calcium carbonate particles. Such calcium carbonate particles which are not part of the calcium carbonate particles of the loaded cellulose fibres are referred to as free calcium carbonate particles, as in the case of the wrapping paper itself. In this case, the proportion of free calcium carbonate particles 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 fibres 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. Note that the above coating corresponds to the composition applied in a dry state, that is, in particular when the solvent has volatilized.

If the composition contains free calcium carbonate particles, the composition must contain a binder for fixing the free calcium carbonate particles to the wrapping paper. This binder also remains in the coating formed by the application of the composition. If the composition contains calcium carbonate particles only in the form of cellulose fibres loaded with them, a binder is not absolutely necessary, but is also preferable for better fixing. Particularly preferably, the binder is selected from the group consisting of starch, starch derivatives, carboxymethyl cellulose, cellulose derivatives, polyvinyl alcohol, galactomannan, gum arabic, alginates and mixtures thereof. Very particularly preferably, the starch is a mechanically fragmented and chemically cross-linked starch, because it is not water-soluble in the chemical sense and therefore penetrates less into the paper structure and reduces the air permeability of the wrapping paper less. The amount of binder can be selected by the skilled person based on his experience, in particular with regard to the requirements of the application process.

The composition may comprise other components that the skilled person can suitably choose, including, for example, combustion salts, coloring substances, flavoring substances, humectants such as glycerol or propylene glycol, or substances to influence viscosity.

The composition can be applied to one or both sides of the wrapping paper. However, it is preferable that the composition is applied to the side that is on the outside of the smoking article made from it. This side is usually already known during the production of the wrapping paper and is in most cases the side facing away from the screen of the paper machine. Therefore, the composition is preferably applied to the side of the wrapping paper facing the outside of the screen of the paper machine, which is also called the top side.

After drying of the applied composition, the mass per unit area of the coating is preferably 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.

In a preferred embodiment, the mass of the free calcium carbonate particles and the calcium carbonate particles of the cellulose fibers filled in the coating is at least 1% and at most 20%, particularly preferably at least 2% and at most 15% of the mass of the coated wrapping paper. In this respect, the wrapping paper preferably further contains cellulose fibers filled with calcium carbonate particles in the mass, the mass of the cellulose fibers filled 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 cellulose fibers filled with calcium carbonate particles constitute at least 10% and at most 60% of the mass of the cellulose fibers filled with calcium carbonate particles.

In a preferred embodiment, the wrapping paper according to the invention can also be a common component of a laminate, particularly preferably a laminate with an additional material with a thermal conductivity exceeding 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 aluminium foil. Such laminates can be used in particular in smoking articles in which the aerosol-forming material is only heated, but not burned, in order to prevent the smoking article from being ignited and smoked like a conventional cigarette.

In a 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 circumferentially printed bands, to reduce the ignition tendency of the smoking article, measured in accordance with ISO 12863:2010.

The grammage of the wrapping paper according to the invention is preferably at least 15 g/m2 and at most 150 g/m2, particularly preferably at least 20 g/m2 and at most 120 g/m2, very particularly preferably at least 20 g/m2 and at most 40 g/m2. The grammage of the wrapping paper can be determined according to ISO 536:2019, whereby the coating, if present, counts towards the grammage.

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, the coating, if present, counts towards the thickness of the wrapping paper.

The mechanical properties of the wrapping paper according to the invention may be of importance for the production of a smoking article from this wrapping paper. The main mechanical properties include tensile strength, breaking strain 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 amount of material and energy required in paper production to increase the tensile strength is high, it is favourable for the tensile strength to be 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 in particular by increasing the grammage and increasing the proportion of cellulose fibres and by grinding the cellulose fibres more intensively.

In order to compensate for the speed differences in the machines used for the production of smoking articles from wrapping paper, it is favourable for the wrapping paper to have a certain elasticity. Preferably, the breaking deformation of the wrapping paper according to the invention is at least 0.9% and at most 3%, particularly preferably at least 1% and at most 2%.

Another important mechanical parameter for the processability of the wrapping paper into a smoking article is its energy absorption capacity. The energy absorption capacity describes how much energy is needed to tear the paper. For the wrapping paper according to the invention, it is preferable that the energy absorption capacity is at least 3 J/m2 and at most 50 J/m2 and very particularly preferably at least 3.5 J/m2 and at most 35 J/m2.

The whiteness (ISO brightness) of the wrapping paper can be important for its visual appearance and also for the ash appearance. It is measured according to ISO 2470-1:2016. White wrapping papers are generally 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 usually favourable because the components of the smoking article are not visible through the wrapping paper. The opacity is measured according to ISO 2471:2008. The opacity of the wrapping paper is preferably 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 in a smoking article, its air permeability is important. In such applications, for example, air must flow through the wrapping paper into the smoking article when the latter is used, in order to dilute the aerosol. Air permeability can be measured according to ISO 2965:2019.

In the case of conventional wrapping papers, those with high air permeability usually have a poor ash appearance, so that in this case the invention can be used particularly advantageously if the content of calcium carbonate particles associated with the cellulose fibers is increased. According to the invention, the wrapping paper 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 constitute at least 20% and at most 80% of the mass of the cellulose fibers loaded with calcium carbonate particles and the wrapping paper has an air permeability according to ISO 2965:2019 of at least 50 cm3/(cm2 minkPa) and at most 300 cm3/(cm2 minkPa).

The above-mentioned preferred and especially preferred ranges for the type and amount of cellulose fibers, the type and amount of cellulose fibers loaded with calcium carbonate particles, the proportion of calcium carbonate particles in the cellulose fibers loaded with calcium carbonate particles, the type and amount of free fillers, the type and amount of combustion salts, as well as mechanical parameters such as tensile strength, breaking strain and energy absorbing capacity and optical parameters such as whiteness and opacity also apply to this particular embodiment. On the other hand, a coating is not preferred for this particular embodiment because it may 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 another preferred embodiment, the smoking article is a smoking article according to the invention, wherein 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 production of the wrapping paper according to the invention and that of the smoking article according to the invention can be carried out using methods known in the prior art.

Brief description of the figures

Figure 1 shows an example of an electron micrograph of cellulose fibers loaded with coarse calcium carbonate particles, where calcium carbonate particles constitute approximately 20% of the mass of the cellulose fibers loaded with calcium carbonate particles.

Figure 2 shows an example of an electron micrograph of cellulose fibers loaded with fine calcium carbonate particles, where calcium carbonate particles constitute approximately 20% of the mass of the cellulose fibers loaded with calcium carbonate particles.

Figure 3 shows the ash appearance of three filter cigarettes made with a wrapping paper not according to the invention.

Figure 4 shows the ash appearance 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 reference wrapping paper not according to the invention had a grammage of 32.6 g/m2 and was produced from 28 % softwood cellulose fibres and 42 % hardwood cellulose fibres as well as 30 % free calcium carbonate particles, where the percentage values refer to the mass of the wrapping paper. Further properties of the wrapping paper can be seen in the "REF" line of Table 1.

A total of 14 wrapping papers were produced according to the invention, designated A to K and X to Z, whereby the composition of the wrapping paper is given in Table 1. In Table 1, "SW" in % indicates the proportion of cellulose fibres from softwoods, "HW' in % the proportion of cellulose fibres from fillers, "CF" in % the proportion of cellulose fibres loaded with calcium carbonate particles and "FI" in % the proportion of free fillers. The percentage values relate in each case to the mass of the wrapping paper.

Cellulose fibres from softwoods and hardwoods are standard products available on the market. Cellulose fibres filled with calcium carbonate particles were purchased from Schaefer Kalk. All free filler material was formed by precipitated calcium carbonate particles.

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

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 coated over its entire surface with a composition of 89 % water, 5.5 % mechanically fragmented and chemically cross-linked starch and 5.5 % free calcium carbonate particles, where the percentage values refer to the mass of the composition. Wrapping papers X and Z were coated over their entire surface with a composition of 95.5 % water, 1 % mechanically fragmented and chemically cross-linked starch and 3.5 % fibres filled with calcium carbonate particles, where the percentage values refer to the mass of the composition. After application and drying of the composition, a mass of approximately 2 g/m2 remained in each case on the wrapping paper.

Mechanically fragmented and chemically cross-linked starch can be obtained, for example, from Emsland-Starke GmbH.

Table 1

The properties of the wrapping paper REF not according to the invention and of the wrapping papers A to K and X to Z according to the invention were determined and are listed in Table 2, where "BW" is the grammage, "EL" is the breaking strain and "AP" is the air permeability.

continued

Table 2

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 wrapping paper REF not according to the invention and from the wrapping papers A to K and X to Z according to the invention. The tobacco used was an American Blend and the wrapping papers each wrapped the tobacco. The ash appearance of these smoking articles was analysed using an image analysis method. For this purpose, three cigarettes were lit upright and the tobacco was allowed to burn completely (smolder). A digital image of each cigarette was then taken under constant lighting conditions against a neutral background. An image analysis software then determined the proportion of non-white surfaces in the area of the smoldering tobacco column. The proportion of these non-white areas in relation to the total surface of the slow-burning tobacco column is expressed as a percentage and is called the "Ash Index", where an average value is formed from the images of three cigarettes in each case. The higher the percentage, the more non-white areas the slow-burning tobacco column contains and the lower the consumer will rate the ash appearance.

The ash index measured in this way is shown in Table 3.

Table 3

Figure 3 shows the ash appearance of three filter cigarettes made from the REF wrapping paper not according to the invention. Figure 4 shows the ash appearance of three filter cigarettes made from the K wrapping paper according to the invention. Even without quantifying the ash appearance by image analysis, the difference is already clearly visible.

The aim of the wrapping papers A to K according to the invention was to achieve properties as similar as possible to the wrapping paper REF not according to the invention, in order to be able to clearly demonstrate the positive effect of cellulose fibres filled with calcium carbonate particles. The examples should therefore not be understood as a limitation of the invention and the skilled person can produce wrapping papers according to the invention with, for example, another composition, another grammage, another thickness, another air permeability or other mechanical or optical properties in the claimed range.

Table 3 shows that the ash content of cigarettes with wrapping papers A to K is always lower than that of cigarettes with the wrapping paper REF not according to the invention. This means that wrapping papers A to K result in a better ash appearance.

Table 2 shows that, as intended for the production of the wrapping papers, the wrapping papers A to K according to the invention are very similar to the wrapping paper REF not according to the invention with regard to grammage, thickness, breaking strain, whiteness and opacity. The tensile strength and thus also the energy absorption capacity of the wrapping papers A to K are somewhat lower than those of the wrapping paper REF not according to the invention. This is due to the cellulose fibres loaded with calcium carbonate particles, since the calcium carbonate particles on the cellulose fibres hinder the formation of hydrogen bonds between the cellulose fibres 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, cigarettes made from the wrapping papers A to K have a better ash appearance than cigarettes made from the REF wrapping paper. This shows that the use of cellulose fibres loaded with calcium carbonate particles offers a very special advantage in the case of high air permeability.

If necessary, the person skilled in the art can of course reduce the air permeability of wrapping papers A to K, for example by grinding the cellulose fibres more intensively, and thus establish the same value as for wrapping paper REF. It is to be expected that the ash number will then drop even further, thereby further improving the ash appearance.

A comparison between wrapping paper I (ash number 7.0), which contains a total of about 36 % free and cellulose fibre-bound calcium carbonate particles, and wrapping paper REF (ash number 11.1) not according to the invention which contains exclusively 40 % free calcium carbonate particles, shows that the ash appearance can be improved despite the lower total content of calcium carbonate particles.

Coated wrapping papers X, Y and Z show an improvement in the ash appearance. Papers X to Z also all have a higher tensile strength than wrapping paper REF not according to the invention and uncoated wrapping papers A to K according to the invention, which is a further advantage of these embodiments.

In general, it can be seen that with the wrapping papers according to the invention a substantial improvement in the ash appearance can be achieved without adversely affecting the other properties of the wrapping paper and without substantially increasing the mass of the wrapping paper or adding unusual components to the wrapping paper.

Claims (15)

1. Wrapping paper for smoking articles, comprising cellulose fibres loaded with calcium carbonate particles, wherein the mass of the cellulose fibres loaded with calcium carbonate particles is at least 10 % of the mass of the wrapping paper and wherein the calcium carbonate particles in the cellulose fibres loaded with calcium carbonate particles constitute at least 20 % and at most 80 % of the mass of the cellulose fibres loaded with calcium carbonate particles and wherein the wrapping paper has an air permeability according to ISO 2965:2019 of at least 50 cm3/(cm2 minkPa) and at most 300 cm3/(cm2 minkPa). 2. Wrapping paper according to claim 1, which in addition to cellulose fibres filled with calcium carbonate particles also comprises cellulose fibres which are not filled with calcium carbonate particles, the proportion of which is at least 1% and at most 95%, preferably at least 10% and at most 80% and very particularly preferably at least 20% and at most 70%, in each case based on the mass of the wrapping paper. 3. Wrapping paper according to claim 1 or 2, wherein the cellulose fibres loaded with calcium carbonate particles and, if present, also the cellulose fibres not loaded with calcium carbonate particles, are obtained at least in part from a softwood, in particular from spruce, pine or fir, from a hardwood, in particular from eucalyptus, birch or beech, or from hemp, flax, jute, sisal, abaca or cotton, and/or in which the cellulose fibres loaded with calcium carbonate particles and, if present, also the cellulose fibres not loaded with calcium carbonate particles are obtained at least in part from regenerated cellulose, and in particular are formed from viscose fibres, modal fibres, Lyocell® or Tencel®. 4. Wrapping paper according to any one of the preceding claims, wherein the cellulose fibres filled with calcium carbonate particles are present at least in part in the mass of the wrapping paper, wherein the proportion of cellulose fibres filled with calcium carbonate particles is preferably at least 5% and at most 80% and particularly preferably at least 30% and at most 70%, in each case based on the mass of the wrapping paper, and/or having a coating, and in which the cellulose fibres loaded with calcium carbonate particles are located at least partly in the coating, wherein their proportion, in the case that the cellulose fibres loaded with calcium carbonate particles are located exclusively in the coating of the wrapping paper, is at least 1 % and at most 30 %, preferably at least 2 % and at most 25 %, in each case based on the mass of the wrapping paper. 5. Wrapping paper according to any one of the preceding claims, wherein the calcium carbonate particles of the cellulose fibres loaded with calcium carbonate particles are formed by precipitated calcium carbonate particles, in particular by precipitated calcium carbonate particles of rhombohedral structure, and/or wherein the mass of the calcium carbonate particles relative to the mass of the cellulose fibres loaded with calcium carbonate particles is at least 10% and at most 70%, preferably at least 20% and at most 60%. 6. Wrapping paper according to any one of the preceding claims, further comprising free fillers which are not bound to the cellulose fibres, the proportion of free fillers preferably being 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. 7. Wrapping paper according to claim 6, wherein the free fillers are formed by carbonates, oxides, hydroxides and silicates or combinations thereof, and in particular are formed by calcium carbonate, preferably precipitated calcium carbonate, magnesium carbonate, magnesium oxide, magnesium hydroxide, aluminum hydroxide, titanium dioxide, talc, kaolin, calcined kaolin and mixtures thereof, and/or wherein the ratio of the mass of calcium carbonate particles contained in the cellulose fibres filled with calcium carbonate particles to the mass of free filler particles in the wrapping paper is from 5:95 to 100:0, preferably from 10:90 to 80:20 and very particularly preferably from 10:90 to 50:50. 8. Wrapping paper according to any one of the preceding claims, further containing combustion salts, 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 very particularly preferably at least 0.5% and at most 3%, in each case based on the mass of the wrapping paper, wherein the combustion salts are preferably 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 are selected from the group consisting of trisodium citrate, tripotassium citrate and mixtures thereof. 9. Wrapping paper according to any one of the preceding claims, wherein at least 95% of its surface has a coating containing free calcium carbonate particles and/or cellulose fibres loaded with calcium carbonate particles, wherein the coating preferably further comprises a binder suitable for fixing the free calcium carbonate particles or the cellulose fibres loaded with calcium carbonate particles in the wrapping 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 combustion salts, colouring substances, flavouring substances, humectants, in particular glycerol or propylene glycol, or substances to influence viscosity, and/or wherein the coating is preferably located on the side of the wrapping paper that is on 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. Wrapping paper according to claim 9, wherein in the coating the mass of the free calcium carbonate particles and the calcium carbonate particles of the cellulose fibres loaded in the coating taken together is at least 1% and at most 20%, particularly preferably at least 2% and at most 15%, wherein the wrapping paper preferably further contains cellulose fibres loaded with calcium carbonate particles in the mass, wherein the mass of the cellulose fibres loaded with calcium carbonate particles in the wrapping paper without the coating is preferably at least 1% and at most 60% of the mass of the wrapping paper and the calcium carbonate particles in the cellulose fibres loaded with calcium carbonate particles constitute at least 10% and at most 60% of the mass of the cellulose fibres loaded with calcium carbonate particles. 11. Wrapping paper according to any one of the preceding claims, wherein the wrapping paper is intended for a cigarette and the wrapping paper has patterns or structures, preferably circumferentially printed bands, to reduce the ignition tendency of the smoking article, measured according to ISO 12863:2010, and/or whose grammage is 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, where a coating, if present, accounts for the grammage of the wrapping paper, and/or whose thickness is at least 10 pm and at most 200 pm, preferably at least 15 pm and at most 120 pm and very particularly preferably at least 30 pm and at most 100 pm, wherein a coating, if present, accounts for the thickness of the wrapping paper. 12. Wrapping paper according to any one of the preceding claims, the tensile strength of which is at least 7 N/15 mm, preferably at least 8 N/15 mm and particularly preferably at least 10 N/15 mm, and/or whose 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, and/or whose breaking strain is at least 0.9% and at most 3%, particularly preferably at least 1% and at most 2%, and/or whose energy absorption capacity is 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. Wrapping paper according to any one of the preceding claims, the whiteness of which according to ISO 2470-1:2016 is at least 80% and particularly preferably at least 90%, and/or whose opacity according to ISO 2471:2008 is at least 70%, and particularly preferably at least 80%, and/or whose air permeability according to ISO 2965:2019 is at least 0 cm3/(cm2 minkPa) and at most 300 cm3/(cm2 minkPa), preferably at least 10 cm3/(cm2 minkPa) and at most 250 cm3/(cm2 minkPa) and particularly preferably at least 20 cm3/(cm2 minkPa) and at most 150 cm3/(cm2 minkPa). 14. Laminate comprising a wrapping paper according to any one of the preceding claims and another material whose thermal conductivity exceeds the thermal conductivity of the wrapping paper by a factor of at least two, preferably at least four, wherein the other material is preferably formed by an aluminium foil. 15. Smoking article comprising an aerosol-forming material and a wrapping paper according to any one of claims 1 to 13, wherein The aerosol-forming material preferably comprises tobacco, wherein the smoking article is preferably a cigarette and the wrapping paper is a cigarette paper, or For its intended use, the aerosol-forming material is preferably only heated, but not burned.