Patent Publication Number: US-2023136404-A1

Title: Wrapper Paper for Smoking Articles, with Improved Ash Formation

Description:
FIELD OF INVENTION 
     The invention relates to a wrapper paper for smoking articles, containing pulp fibers loaded with filler particles, which provide advantageous properties to the paper. In particular, the ash from a smoking article manufactured from this wrapper paper has a better appearance. 
     BACKGROUND AND PRIOR ART 
     A common smoking article comprises a cylindrical tobacco rod that contains an aerosol-forming material, typically tobacco or a tobacco-based material, which is wrapped with a wrapper material. In most cases, the wrapper material comprises a paper, i.e. a web-shaped material, which contains pulp fibers. Furthermore, a smoking article can comprise a filter that is wrapped with a filter wrapper paper, and a tipping paper that wraps both the filter and a part of the tobacco rod und connects the filter and the tobacco rod to each other thereby. 
     During use of the smoking article, the aerosol-forming material is heated or burnt so that an aerosol is formed which, during use of the smoking article, flows through the smoking article and is inhaled by the consumer. 
     In particular, if the aerosol-forming material is just heated but not burnt, the smoking article can also comprise further components which transfer the aerosol or cool the aerosol and are typically arranged between the tobacco rod and the filter. 
     During burning or heating of the tobacco rod to release the aerosol, the wrapper paper of the tobacco rod is thermally degraded. As a result, the wrapper paper can be discolored, and it loses part of its mechanical stability, for which reason the optical appearance of the smoking article changes. This appearance of a used smoking article or of a smoking article which is being used, and particularly its tobacco rod, is called ash appearance. 
     From the consumer&#39;s viewpoint, it is a sign of high quality of the smoking article if it has a good ash appearance, i.e. if the tobacco rod substantially maintains its cylindrical shape after burning or heating, has a uniform white color, and no dark particles, for example tobacco particles or their ash, protrude through the wrapper material. 
     In the prior art various options are known to improve the ash appearance of a smoking article. As an example, the basis weight of the wrapper paper can be increased, or burn additives such as trisodium citrate or tripotassium citrate can be added or their content can be increased. These options have the disadvantage that they increase the proportion of non-tobacco materials in the smoking article and can therefore have a negative impact on the taste of the smoking article. Thus, there is an interest in improving the ash appearance of a smoking article without adding new components to the wrapper paper or substantially increasing its mass. This interest relates not only to the wrapper paper that directly wraps the aerosol-forming material, but generally also relates to wrapper papers for other components of the smoking article, in particular those that can also be exposed to the high temperatures of the aerosol. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The term “wrapper paper” as used below should be understood to mean that paper which wraps the smoking article or at least one of its components. 
     The objective of the invention is to provide a wrapper paper for smoking articles that provides the smoking article with a good ash appearance without having to substantially increase the mass of the wrapper paper or having to add uncommon components to the wrapper paper. 
     This objective is achieved by a wrapper paper for a smoking article according to claim  1 , a laminate according to claim  32  and a smoking article according to claim  33  comprising this wrapper paper. Advantageous embodiments are provided in the dependent claims. 
     The inventor has found that this objective can be achieved by a wrapper paper with contains pulp fibers that are loaded with calcium carbonate particles. Pulp fibers and calcium carbonate particles are common components of wrapper papers for smoking articles, however in the prior art, the calcium carbonate particles are not bonded to the pulp fibers, but are only disposed between the pulp fibers. Calcium carbonate particles of this type are called “free calcium carbonate particles” in order to differentiate them from calcium carbonate particles with which the pulp fibers are loaded, i.e. which are bonded to them. Such pulp fibers loaded with calcium carbonate particles can, for example, be produced by precipitation of the calcium carbonate with the simultaneous presence of the pulp fibers under suitable control of the precipitation process. 
     Specifically, the wrapper paper according to the invention comprises pulp fibers loaded with calcium carbonate particles, wherein the mass of the pulp fibers loaded with calcium carbonate particles is at least 1% 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 5% and at most 80% of the mass of the pulp fibers loaded with calcium carbonate particles. 
     The inventor assumes that the calcium carbonate particles bonded to the pulp fibers form a framework that remains after the thermal degradation of the pulp fibers and thereby ensures the stability of the thermally degraded wrapper paper and thereby prevents, for example, ash particles of the aerosol-forming material from penetrating the wrapper paper. In this manner, the ash appearance of the smoking article is improved overall. In contrast thereto, the free calcium carbonate particles do not form such framework-like structures and do not contribute to the improvement of the ash appearance to the same extent. Thus, for a comparable ash appearance by using pulp fibers loaded with calcium carbonate particles, the mass of calcium carbonate particles in the wrapper paper can be reduced or the overall mass of the wrapper paper can be reduced. This also reduces the influence of the wrapper paper on the taste of the smoking article. 
     The wrapper paper according to the invention offers particular advantages when it has a high air permeability. A conventional wrapper paper with high air permeability has more and larger pores and cannot form a mechanically stable framework as well during thermal degradation, for which reason the ash appearance is often not acceptable. This effect can be substantially compensated for by the pulp fibers loaded with calcium carbonate particles in the wrapper paper according to the invention. 
     In some embodiments, all of the pulp fibers in the wrapper paper are loaded with calcium carbonate particles. However, it can also be envisaged that aside from the pulp fibers loaded with calcium carbonate particles, the wrapper paper also contains pulp fibers that are not loaded with calcium carbonate particles. The proportion of such pulp fibers is preferably at least 1% and at most 95%, particularly preferably at least 10% and at most 80% and more particularly preferably at least 20% and at most 70%, each with respect to the mass of the wrapper paper. 
     The pulp fibers as well as the pulp fibers loaded with calcium carbonate particles can be sourced from coniferous wood such as spruce, pine or fir, from deciduous wood such as eucalyptus, birch or beech, or from other plants such as hemp, flax, jute, sisal,  abaci  or cotton. 
     The pulp fibers can also be sourced from regenerated cellulose such as, for example, viscose fibers, modal fibers Lyocell® or Tencel®. Mixtures of pulp fibers from various origins can be used. 
     The wrapper paper according to the invention contains at least 1% of pulp fibers loaded with calcium carbonate particles. The wrapper paper can be uncoated or coated. In this regard, the pulp fibers loaded with calcium carbonate particles can be in the bulk of the wrapper paper or in an optional coating on the wrapper paper. If the pulp fibers loaded with calcium carbonate particles are in the bulk of the wrapper paper, the proportion of pulp fibers loaded with calcium carbonate particles is preferably higher and is 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. If the pulp fibers loaded with calcium carbonate particles are exclusively located in the optional coating of the wrapper paper, then the proportion of the pulp fibers loaded with calcium carbonate particles is preferably at least 1% and at most 30% and particularly preferably at least 2% and at most 25%, each with respect to the mass of the wrapper paper. 
     A high proportion of pulp fibers loaded with calcium carbonate particles enables the proportion of free calcium carbonate particles to be reduced, and at the same time enables the ash appearance to be improved. It is even possible that, by using the pulp fibers loaded with calcium carbonate particles, the total content of calcium carbonate particles in the wrapper paper can be reduced without worsening the ash appearance. However, the pulp fibers loaded with calcium carbonate particles form fewer hydrogen bonds so that as a whole, the tensile strength of the wrapper paper can be reduced. Thus, the amount of pulp fibers loaded with calcium carbonate particles in the wrapper paper cannot be selected arbitrarily, particularly if the pulp fibers are loaded with a large amount of calcium carbonate particles. 
     Preferably, the pulp fibers loaded with calcium carbonate particles are sourced from deciduous wood such as eucalyptus, birch or beech. These pulp fibers are in general less mechanically stressed during the manufacture of the wrapper paper, for example during refining, so that fewer calcium carbonate particles can be lost during the manufacturing process. 
     The calcium carbonate particles of the pulp 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 on the pulp fibers can be produced particularly well in a precipitation process. 
     The mass of the calcium carbonate particles with respect to the mass of the pulp fibers loaded with calcium carbonate particles in the wrapper paper according to the invention is at least 5% and at most 80%. Preferably, it is at least 10% and at most 70% and more particularly preferably at least 20% and at most 60%. The preferred intervals result in a particularly good compromise between the desired improvement of the ash appearance and the undesired reduction in tensile strength. 
     The wrapper paper can also contain free filler materials that are not bonded to the pulp fibers. The proportion of free filler material 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. These filler materials can serve to influence the brightness, the opacity and the pore structure of the wrapper paper. However, a high free filler materials content reduces the tensile strength of the wrapper paper. In addition, with free filler materials there is the danger that they are deposited as dust in further processing steps, for example during manufacture of a smoking article, und thus reduce the intervals needed between cleans of the machines. In the preferred intervals, the advantages of the use of free filler materials predominate. 
     The free filler materials in the wrapper paper are preferably carbonates, oxides, hydroxides and silicates. Particularly preferred filler materials are calcium carbonate, magnesium carbonate, magnesium oxide, magnesium hydroxide, aluminum hydroxide, titanium dioxide, talcum, kaolin, calcinated kaolin and mixtures thereof. Precipitated calcium carbonate is highly particularly preferred. 
     The ratio of the mass of calcium carbonate particles which are contained in the pulp fibers loaded with calcium carbonate particles and the mass of free filler material particles in the wrapper paper can be of importance for the adjustment of the ash appearance with respect to other properties such as brightness, opacity and tensile strength. Preferably, 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; particularly preferably, it is 10:90 to 80:20 and in particular it is 10:90 to 50:50. 
     The wrapper paper can also contain burn additives. The burn additives influence the speed of thermal degradation of the wrapper paper and can also contribute to the improvement of the ash appearance, because they act in part as an adhesive or as a sintering agent between the free filler material particles and in this way they improve the mechanical stability of the thermally degraded wrapper paper. Burn additives can preferably be used in that wrapper paper which wraps the tobacco rod. 
     The proportion of burn additives in the wrapper paper can be selected in a variable manner, wherein the proportion 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. 
     The burn additives can preferably be 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, particularly preferably from the group consisting of trisodium citrate, tripotassium citrate and mixtures thereof. 
     In one embodiment of the wrapper paper, the wrapper paper is provided over substantially the entire surface with a coating that contains free calcium carbonate particles and/or pulp fibers loaded with calcium carbonate particles. In this regard, coated “over substantially the entire surface” means that a full-surface coating is intended or that at least 95% of the surface is coated. A suitably selected coating can further improve the ash appearance without adding uncommon components to the wrapper 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 wrapper paper after its thermal degradation. 
     The coating can be carried out by the application of a composition by means of processes that are known in the art such as, for example, in the size press or a film press of a paper machine, in coating units or by means of a printing machine, in particular a rotogravure printing machine. 
     As a result, a composition that is suitable for the manufacture of the coating comprises a solvent, preferably water, and calcium carbonate particles or pulp fibers loaded with calcium carbonate particles. Such calcium carbonate particles, which do not belong to the calcium carbonate particles of the loaded pulp fibers, are called free calcium carbonate particles, as is the case for the wrapper 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%, each with respect to the mass of the composition. The proportion of the pulp 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%, each with respect to the mass of the composition. It should be noted that the aforementioned coating corresponds to the applied composition in the dried state, i.e. when, in particular, the solvent has volatilized. 
     If the composition contains free calcium carbonate particles, the composition should contain a binder in order to fix the free calcium carbonate particles to the wrapper paper. This binder then also remains in the coating formed by application of the composition. If the composition just contains calcium carbonate particles in the form of pulp fibers loaded with calcium carbonate particles, a binder is not absolutely required, but is also preferred for a better immobilization. Particularly preferably, the binder is selected from the group consisting of starch, starch derivatives, carboxy methyl cellulose, cellulose derivatives, polyvinyl alcohol, galactomannan, gum Arabic, alginates and mixtures thereof. In particular, the starch is a mechanically fragmented and chemically cross-linked starch because it is not soluble in water in the chemical sense and therefore penetrates less into the paper structure and so reduces the air permeability of the wrapper paper less. The skilled person can select the amount of binder from experience, in particular, with respect to the requirements of the application process. 
     The composition can comprise further components, that the skilled person can select to suit; this includes, for example, burn additives, colorants, flavors, humectants such as glycerol or propylene glycol, or substances for influencing viscosity. 
     The application of the composition can be carried out on one or both sides of the wrapper paper. Preferably, however, the composition is applied to the side which is facing the outside on a smoking article manufactured therefrom. This is generally known during manufacture of the wrapper paper and is in most cases the side facing away from the wire of the paper machine. 
     Thus, preferably, the composition is applied to the side of the wrapper paper facing away from the wire of the paper machine, which is also called felt side. 
     After drying the applied composition, the mass per unit area 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 taken together 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 wrapper paper. In this regard, the bulk of the wrapper paper preferably additionally contains pulp fibers loaded with calcium carbonate particles, 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 70%, particularly 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. 
     In a preferred embodiment, the wrapper paper according to the invention can also be a component of a laminate, particularly preferably a laminate with a further material with a thermal conductivity that exceeds that of the wrapper paper by a factor of at least two, preferably of at least four. In particularly preferred embodiments, this further material is formed by an aluminum foil. Such laminates can primarily be used in smoking articles, in which the aerosol-forming material is only heated but not burnt, to prevent the smoking article from being lit and smoked like a conventional cigarette. 
     In a further preferred embodiment of the wrapper paper for a smoking article, the smoking article is a cigarette and the wrapper paper is additionally equipped with a pattern or structures, particularly preferably printed bands in the circumferential direction, to reduce the ignition propensity of the smoking article measured in accordance with ISO 12863:2010. 
     The basis weight of the wrapper 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 , more particularly preferably at least 20 g/m 2  and at most 40 g/m 2 . The basis weight of the wrapper paper can be determined in accordance with ISO 536:2019, wherein the coating, if present, counts towards the basis weight. 
     The thickness of the wrapper 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 more particularly preferably at least 30 μm and at most 100 μm. The thickness can be determined in accordance with ISO 534:2011 on a single layer of the wrapper paper. Here again, a coating, if present, counts towards the thickness of the wrapper paper. 
     The mechanical properties of the wrapper paper according to the invention can be of importance for the manufacture of a smoking article from this wrapper paper. Tensile strength, elongation at break and tensile energy absorption are some of the essential mechanical properties and can all be determined in accordance with ISO 1924-2:2008. 
     The tensile strength of the wrapper paper is preferably at least 7 N/15 mm, particularly preferably at least 8 N/15 mm and more particularly preferably at least 10 N/15 mm. Since the cost in material and energy for increasing the tensile strength is high in paper manufacturing, it is advantageous for the tensile strength to have 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 primarily be increased by increasing the basis weight and by increasing the proportion of pulp fibers, as well as by more intensive refining of the pulp fibers. 
     In order to compensate for differences in the speeds of the machines for the manufacture of smoking articles from the wrapper paper, it is advantageous for the wrapper paper to have a certain elongation at break. Preferably, the elongation at break of the wrapper paper according to the invention is at least 0.9% and at most 3%, particularly preferably at least 1% and at most 2%. 
     A further mechanical parameter that is of importance for the processability of the wrapper paper to form a smoking article is the tensile energy absorption. The tensile energy absorption describes how much energy is required to tear the paper. For the wrapper paper according to the invention it is preferable for the tensile energy absorption to be at least 3 J/m 2  and at most 50 J/m 2  and particularly preferably at least 3.5 J/m 2  and at most 35 J/m 2 . 
     The brightness (ISO brightness) of the wrapper paper can be of importance to its optical appearance and also for the ash appearance. It is measured in accordance with ISO 2470-1:2016. In general, white wrapper papers are preferred for optical reasons, so that the brightness of the wrapper paper according to the invention is at least 80% and particularly preferably at least 90%. 
     The brightness can be influenced, for example, by selection of the free filler materials; in particular, the brightness can be substantially increased by the use of titanium dioxide. 
     The opacity of the wrapper paper is also of importance to the optical appearance. A high opacity is generally advantageous, because then the components of the smoking article are not visible through the wrapper paper. The opacity is measured in accordance with ISO 2471:2008. Preferably, the opacity of the wrapper paper is at least 70% and particularly preferably at least 80%. The opacity can also be increased by increasing the amount of free filler materials in the wrapper paper. 
     In certain applications of the wrapper paper according to the invention on a smoking article, its air permeability is of importance. In such applications, for example, air ought to flow through the wrapper paper into the smoking article during use of the smoking article in order to dilute the aerosol. The air permeability can be measured in accordance with ISO 2965:2019. 
     The air permeability of the wrapper paper according to the invention is preferably at least 0 cm 3 /(cm 2 ·min·kPa) and at most 300 cm 3 /(cm 2 ·min·kPa), particularly preferably at least 10 cm 3 /(cm 2 ·min·kPa) and at most 250 cm 3 /(cm 2 ·min·kPa) and in particular at least 20 cm 3 /(cm 2 ·min·kPa) and at most 150 cm 3 /(cm 2 ·min·kPa). If the wrapper paper is coated, its air permeability is lower and is at most 120 cm 3 /(cm 2 ·min·kPa), particularly preferably at most 100 cm 3 /(cm 2 ·min·kPa) and more particularly preferably at most 80 cm 3 /(cm 2 ·min·kPa). 
     In conventional wrapper papers, those with a high air permeability generally have a poorer ash appearance, so that in this case, the invention can be used particularly advantageously if the content of calcium carbonate particles that are bonded to the pulp fibers is increased. In a particular embodiment of the invention, the wrapper paper according to the invention 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 cm 3 /(cm 2 ·min·kPa) and at most 300 cm 3 /(cm 2 ·min·kPa). 
     The aforementioned preferred and particularly preferred intervals regarding type and amount of pulp fibers, type and amount of pulp fibers loaded with calcium carbonate particles, content of calcium carbonate particles in the pulp fibers loaded with calcium carbonate particles, type and amount of free filler materials, type and amount of burn additives, as well as regarding the mechanical parameters such as tensile strength, elongation at break and tensile energy absorption and optical parameters such as brightness and opacity are also valid for this particular embodiment. A coating, however, is not preferred for this particular embodiment, because it can reduce the air permeability too much. 
     A smoking article according to the invention comprises an aerosol-forming material and the wrapper paper according to the invention. In a preferred embodiment of the smoking article, the aerosol-forming material comprises tobacco and said wrapper paper wraps the aerosol-forming material. 
     In a further preferred embodiment, the smoking article is a smoking article according to the invention, wherein the aerosol-forming material is only heated but not burnt. 
     In a particularly preferred embodiment, the smoking article is a cigarette and the wrapper paper is a cigarette paper. 
     The manufacture of the wrapper paper according to the invention and the smoking article according to the invention can be carried out using methods that are known in the art. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG.  1    shows, by way of example, an electron micrograph of pulp fibers loaded with coarse calcium carbonate particles, wherein the calcium carbonate particles make up about 20% of the mass of the pulp fibers loaded with calcium carbonate particles. 
         FIG.  2    shows, by way of example, an electron micrograph of pulp fibers loaded with fine calcium carbonate particles, wherein 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 appearance of three filter cigarettes made from a wrapper paper not according to the invention. 
         FIG.  4    shows the ash appearance of three filter cigarettes made from a wrapper paper according to the invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Some preferred embodiments of wrapper papers according to the invention are described below and are compared with a wrapper paper not according to the invention. 
     The wrapper paper not according to the invention, which serves as a reference, has a basis weight of 32.6 g/m 2  and was manufactured from 28% pulp fibers from coniferous wood and 42% pulp fibers from deciduous wood as well as 30% free calcium carbonate particles, wherein the percentages are with respect to the mass of the wrapper paper. Further properties of the wrapper paper are shown in Table 1 in the row “REF”. 
     In total, 14 wrapper papers according to the invention, designated by A to K and X to Z, were manufactured, wherein the composition of the wrapper papers is shown in Table 1. In Table 1, “SW” in % indicates the proportion of pulp fibers from coniferous woods, “HW” in % indicates the proportion of pulp fibers from deciduous woods, “CF” in % indicates the proportion of pulp fibers loaded with calcium carbonate particles and “FI” in % indicates the proportion of free filler materials. The percentages are with respect to the mass of the wrapper paper. 
     The pulp fibers from coniferous and deciduous wood types are standard products available on the market. The pulp fibers loaded with calcium carbonate particles were obtained from the company Schaefer Kalk. The entire free filler was formed by precipitated calcium carbonate particles. 
     Furthermore, in Table 1 under “CCP”, the mass of the calcium carbonate particles in the pulp fibers loaded with calcium carbonate particles is given as a % with respect to the mass of pulp fibers loaded with calcium carbonate particles. In addition, the size of these particles is indicated as “fine” or “coarse”. In this context,  FIG.  1    shows an electron micrograph of pulp fibers loaded with coarse calcium carbonate particles and  FIG.  2    shows an electron micrograph of pulp fibers loaded with fine calcium carbonate particles, in the way both were used for the manufacture of some wrapper papers according to the invention. The proportion by weight of the calcium carbonate particles in the pulp fibers loaded with calcium carbonate particles from  FIGS.  1  and  2    was about 17.3%. The pulp fibers were formed by pulp fibers from eucalyptus. 
     The wrapper paper X was identical to the wrapper paper REF and the wrapper papers Y and Z were identical to wrapper paper G. The entire surface of the wrapper paper Y was coated with a composition of 89% water, 5.5% mechanically fragmented and chemically cross-linked starch and 5.5% free calcium carbonate particles, wherein the percentages are with respect to the mass of the composition. The entire surface of the wrapper papers X and Z were coated with a composition of 95.5% water, 1% mechanically fragmented and chemically cross-linked starch and 3.5% pulp fibers loaded with calcium carbonate particles, wherein the percentages are with respect to the mass of the composition. After application and drying of the composition, a mass of about 2 g/m 2  remained on the wrapper papers. 
     The mechanically fragmented, chemically cross-linked starch can, for example, be obtained from the company Emsland-Stärke GmbH. 
     
       
         
           
               
               
               
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                 CCP 
                   
                 CF 
                 SW 
                 HW 
                 FI 
               
               
                   
                 Paper 
                 % 
                 Size 
                 % 
                 % 
                 % 
                 % 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                 REF 
                   
                   
                 0 
                 28 
                 42 
                 30 
               
               
                   
                 A 
                 25.3 
                 fine 
                 42 
                 28 
                 0 
                 30 
               
               
                   
                 B 
                 25.3 
                 fine 
                 36 
                 24 
                 0 
                 40 
               
               
                   
                 C 
                 17.3 
                 coarse 
                 21 
                 28 
                 21 
                 30 
               
               
                   
                 D 
                 17.3 
                 coarse 
                 18 
                 24 
                 18 
                 40 
               
               
                   
                 E 
                 17.3 
                 coarse 
                 42 
                 28 
                 0 
                 30 
               
               
                   
                 F 
                 17.3 
                 coarse 
                 36 
                 24 
                 0 
                 40 
               
               
                   
                 G 
                 25.5 
                 coarse 
                 42 
                 28 
                 0 
                 30 
               
               
                   
                 H 
                 25.5 
                 coarse 
                 36 
                 24 
                 0 
                 40 
               
               
                   
                 I 
                 33.7 
                 coarse 
                 21 
                 28 
                 21 
                 30 
               
               
                   
                 J 
                 33.7 
                 coarse 
                 42 
                 28 
                 0 
                 30 
               
               
                   
                 K 
                 33.7 
                 coarse 
                 36 
                 24 
                 0 
                 40 
               
               
                   
                 X 
                   
                   
                 0 
                 28 
                 42 
                 30 
               
               
                   
                 Y 
                 25.5 
                 coarse 
                 42 
                 28 
                 0 
                 30 
               
               
                   
                 Z 
                 25.5 
                 coarse 
                 42 
                 28 
                 0 
                 30 
               
               
                   
                   
               
            
           
         
       
     
     The properties of the wrapper paper REF not according to the invention and the wrapper papers A to K and X to Z according to the invention were determined and are shown in Table 2, wherein “BW” is the basis weight, “EL” is the elongation at break and “AP” is the air permeability. 
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                   
                   
                   
                 Tensile 
                   
                   
                   
                   
                   
               
               
                   
                   
                 Thick- 
                 Strength 
                   
                   
                 Bright- 
                 Opa- 
                 AP 
               
               
                   
                 BW 
                 ness 
                 N/15 
                 EL 
                 TEA 
                 ness 
                 city 
                 cm 3 /(cm 2  · 
               
               
                 Paper 
                 g/m 2   
                 μm 
                 mm 
                 % 
                 J/m 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 about 7.8 mm and a length of 83 mm were manufactured from the wrapper paper REF not according to the invention and the wrapper papers A to K and X to Z according to the invention. The tobacco used was an American Blend and the wrapper papers each wrapped the tobacco. The ash appearance of these smoking articles was assessed by means of an image analysis method. In this regard three pieces from each cigarette were lit in a vertical position and left until complete combustion of the tobacco. Next, a digital image of each cigarette was taken under constant lighting conditions in front of a neutral background. Then image analysis software determined the proportion of non-white areas in the region of the combusted tobacco rod. This proportion of non-white areas with respect to the total area of the combusted tobacco rod was expressed as a percentage and reported as “Ash Index”, wherein a mean value was determined from the images of three cigarettes. The higher the percentage, the more non-white areas are contained in the combusted tobacco rod and the worse the consumer will judge the ash appearance. 
     The Ash Index determined in this manner is shown in Table 3. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                   
                 Ash Index 
               
               
                   
                 Paper 
                 % 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 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 
               
               
                   
                   
               
            
           
         
       
     
       FIG.  3    shows the ash appearance of three filter cigarettes that were manufactured from the wrapper paper REF not according to the invention.  FIG.  4    shows the ash appearance of three filter cigarettes that were manufactured from wrapper paper K according to the invention. Even without quantifying the ash appearance by image analysis, the difference is already clearly visible. 
     The purpose of wrapper papers A to K according to the invention was to achieve properties as similar as possible compared with the wrapper paper REF not according to the invention, to be able to clearly show the positive effect of the pulp fibers loaded with calcium carbonate particles. The examples are thus not to be understood as limiting the invention and the skilled person will be able to manufacture wrapper papers according to the invention with, for example, a different composition, different basis weight, different thickness, different air permeability or other mechanical or optical properties within the claimed range. 
     From Table 3 it can be seen that the Ash Index of cigarettes with wrapper papers A to K is always lower than that of cigarette with wrapper paper REF not according to the invention. This means that wrapper papers A to K lead to a better ash appearance. 
     From Table 2 it can be seen that, as was intended by the manufacture of the wrapper papers, wrapper papers A to K according to the invention are very similar to wrapper paper REF not according to the invention with respect to basis weight, thickness, elongation at break, brightness and opacity. The tensile strength and hence also the tensile energy absorption of wrapper papers A to K is slightly lower than for wrapper paper REF not according to the invention. This is caused by the pulp fibers loaded with calcium carbonate particles, because the calcium carbonate particles on the pulp fibers prevent the formation of hydrogen bonds between the pulp fibers and therefore reduce the tensile strength of the wrapper paper. 
     It is important that the air permeability of wrapper papers A to K is higher than that of the wrapper paper not according to the invention. Despite this higher air permeability, the cigarettes manufactured from wrapper papers A to K have a better ash appearance than the cigarettes produced from wrapper paper REF. This shows that at high air permeability, the use of pulp fibers loaded with calcium carbonate particles offers a particular advantage. 
     If needed, the skilled person can, of course, reduce the air permeability of wrapper papers A to K, for example by more intensive refining of the pulp fibers, and therefore obtain the same value as for wrapper paper REF. It is then to be expected that the Ash Index will decrease further, and the ash appearance will improve even further. 
     A comparison between wrapper paper I (Ash Index 7.9), which in total contains about 36% calcium carbonate particles, free and bound to the pulp fibers, and the wrapper paper REF not according to the invention (Ash Index 11.1), which contains 40% exclusively free calcium carbonate particles, shows that the ash appearance can be improved despite the lower total content of calcium carbonate particles. 
     The coated wrapper papers X, Y and Z all exhibit an improvement in the ash appearance. Papers X to Z also all have a higher tensile strength than wrapper paper REF not according to the invention and than the uncoated wrapper papers A to K according to the invention, which is a further advantage of these embodiments. 
     In total, it can be seen that with the wrapper papers according to the invention a substantial improvement in the ash appearance can be achieved without having a negative influence on other properties of the wrapper paper and without substantially increasing the mass of the wrapper paper or adding uncommon components to the wrapper paper.