Deeply Embossed Highly Permeable Cigarette Paper

Abstract

A smoking article wrapper includes a non-perforated air permeable base paper having a naturally high porosity of 40-80 cm.sup.3/min air passing through a sample of 1 cm.sup.2 of this base paper at an applied pressure difference of 1 kPa, wherein the smoking article wrapper has at least one embossed surface area and at least one non-embossed surface area. The air permeability of the smoking article wrapper is such that it provides a mean volumetric flow rate of ≥40 cm.sup.3/min air passing through a sample of 1 cm.sup.2 of this smoking article wrapper at an applied pressure difference of 1 kPa. The embossed area includes an embossing having a depth of ≥16 μm. A smoking article including the smoking article wrapper and respective methods to produce such a smoking article wrapper and a smoking article are also provided.

Claims

1. A smoking article wrapper comprising a non-perforated air permeable base paper having a naturally high porosity of 40-80 cm.sup.3/min of air passing through a sample of 1 cm.sup.2 of the base paper at an applied pressure difference of 1 kPa, wherein the smoking article wrapper has at least one embossed surface area and at least one non-embossed surface area, wherein an air permeability of the smoking article wrapper provides a mean volumetric flow rate of ≥40 cm.sup.3/min of air passing through a sample of 1 cm.sup.2 of the smoking article wrapper at an applied pressure difference of 1 kPa and in that the at least one embossed surface area comprises an embossing having a depth of ≥16 μm.

2. The smoking article wrapper according to claim 1, wherein the smoking article wrapper provides an air permeability in a range of a mean volumetric flow rate of 40-60 cm.sup.3 min.sup.−1 of air passing through a sample of 1 cm.sup.2 of the smoking article wrapper at an applied pressure difference of 1 kPa.

3. The smoking article wrapper according to claim 1, wherein the depth of the embossing is in a range of 16-30 μm.

4. The smoking article wrapper according to claim 1, wherein the base paper has a weight of 25-60 g/m.sup.2.

5. The smoking article wrapper according to claim 1, wherein the at least one non-embossed surface area of the base paper provides an air permeability in a range of a mean volumetric flow rate of 42-75 cm.sup.3 min.sup.−1 of air passing through a sample of 1 cm.sup.2 of the base paper at an applied pressure difference of 1 kPa.

6. The smoking article wrapper according to claim 1, wherein the base paper comprises a filler, wherein a content of the filler is 30-60% (w/w).

7. The smoking article wrapper according to claim 1, wherein a percentage of the at least one embossed surface area is less than 50% of a total surface area of the smoking article wrapper.

8. A smoking article comprising the smoking article wrapper according to claim 1.

9. The smoking article according to claim 8, further comprising a mouthpiece and an aerosol generating substrate, wherein the aerosol generating substrate is wrapped in the smoking article wrapper.

10. The smoking article according to claim 8, wherein a CO/Tar value of the smoking article is between 1 and 1.43.

11. The smoking article according to claim 8, wherein a tar level of the smoking article according to DIN ISO 4387:2018-09 is between 1 mg and 10 mg.

12. A method for producing a smoking article wrapper, which is permeable for air and provides a mean volumetric flow rate of ≥40 cm.sup.3 min.sup.−1 of air passing through a sample of 1 cm.sup.2 of the smoking article wrapper at an applied pressure difference of 1 kPa, comprising: providing a non-perforated air-permeable base paper having a naturally high porosity of 40-80 cm.sup.3 min.sup.−1 of air passing through a sample of 1 cm.sup.2 of the base paper at an applied pressure difference of 1 kPa, generating an embossing having a depth of ≥16 μm by application of pressure on parts of a surface area of the base paper.

13. The method according to claim 12, wherein the smoking article wrapper provides an air permeability in a range of a mean volumetric flow rate of 42-75 cm.sup.3 min.sup.−1 of air passing through a sample of 1 cm.sup.2 of the base paper at an applied pressure difference of 1 kPa and/or has a weight of 25-60 g/m.sup.2.

14. The method according to claim 12, wherein the step of generating the embossing includes application of pressure on less than 50% of the surface area of the base paper.

15. The method according to claim 12, wherein the step of generating the embossing includes application of pressure of at least 4 MPa.

16. A method for producing a smoking article, comprising: manufacturing a smoking article wrapper with the method according to claim 12, providing a mouthpiece and an aerosol generating substrate, and wrapping the aerosol generating substrate in the smoking article wrapper.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Further advantages, objectives and features of the present invention will be described, by way of example only, in the following description with reference to the appended figures. In the figures, like components in different embodiments can exhibit the same reference symbols.

[0038] The figures show:

[0039] FIG. 1a an image of an exemplary embodiment of a smoking article wrapper according to the invention;

[0040] FIG. 1b an image of an exemplary smoking article wrapper having a similar but less deep embossing pattern than the smoking article wrapper of FIG. 1a;

[0041] FIG. 2a an image of a further exemplary embodiment of a smoking article wrapper according to the invention;

[0042] FIG. 2b an image of a further exemplary smoking article wrapper having a similar but less deep embossing pattern than the smoking article wrapper of FIG. 2a;

[0043] FIG. 3a a detailed image of the embossing as illustrated in FIG. 1a;

[0044] FIG. 3b a diagram showing the height profile of the smoking article wrapper as illustrated in FIG. 3a along the indicated path 13;

[0045] FIG. 4a a detailed image of the embossing as illustrated in FIG. 2b;

[0046] FIG. 4b a diagram showing the height profile of the smoking article wrapper as illustrated in FIG. 4a along the indicated path 13;

[0047] FIG. 5 a diagram showing the relation between the porosity of smoking article wrapper and its surface area covered by embossed features.

DETAILED DESCRIPTION

[0048] FIG. 1a shows an image of an exemplary embodiment of a smoking article wrapper 1 according to the invention. To obtain the picture of FIG. 1a, the smoking article wrapper 1 was illuminated from the backside. Thus, FIG. 1a can give hints about the opacity of different areas of the smoking article wrapper 1. In FIG. 1a only a small sample of a smoking article wrapper 1 is shown. Such a smoking article wrapper 1 could be part of a smoking article. Usually such smoking article wrapper 1 is produced as a continuous band of paper-based material wound in a bobbin or equivalently reeled fashion. During production of smoking articles such as cigarettes the band is unreeled in a smoking article machine to wrap a continuous strand of aerosol-generating material, for example of tobacco material, which is then cut in rods to form a plurality of smoking articles.

[0049] The illustrated smoking article wrapper 1 has an embossing. The pattern 10 of the embossing consists of a plurality of parallel lines 11. Due to the applied pressure during the embossing procedure, the base paper material is highly compressed in these areas. Less light is shining through the smoking article wrapper 1 in the embossed areas 11. Thus, these areas are darker than the non-embossed areas 12. Due to the depth of the embossing and the high compression of the base paper material in these areas, the embossed lines 11 occur homogeneously black. In contrast thereto, the non-embossed areas 12 are less homogeneous, due to the chaotical arrangement of the base material fibers of the base paper. Since the fibers of the base paper material are stacked higher in some areas than in others, less light is transmitted in these areas. Due to the higher amount of light absorbing material arranged in these areas, these areas occur darker than the others.

[0050] FIG. 1b shows an image of an exemplary smoking article wrapper 1 having a similar or even the same pattern 10 of the embossing as the smoking article wrapper shown in FIG. 1a. However, the depth of the embossing 11 is lower. The pressure for application of the embossing 10 was lower than that used for application of the embossing 10 as illustrated in FIG. 1a. As a result of the reduced pressure, the contrast of light transmission between the embossed areas 11 and the non-embossed areas 12 is low. In contrast to the smoking article wrapper shown in FIG. 1a, the embossed lines 11 occur lighter and they are interrupted often.

[0051] Due to the higher contrast and the improved haptical properties of a deeper embossing, a smoking article comprising a wrapper having such an embossing may appear more valuable to smoking articles consumers. A luxury appearance could be established.

[0052] FIGS. 2a and 2b show further exemplary embodiments of smoking article wrappers 1 according to the invention. Similar to the embodiment shown in FIG. 1a, the smoking article wrappers 1 are illuminated from the backside and the opacity of different areas 11, 12 of the smoking article wrapper 1 could be recognized. The pattern 10 of the embossing differs from the pattern shown in FIGS. 1a and 1b. It consists of a plurality of lines 11 forming the letter “W”.

[0053] Like FIGS. 1a and 1b, also the embossing shown in FIG. 2a is applied at higher pressure than that shown in FIG. 2b. Due to the higher pressure for application of the embossing 10 shown in FIG. 2a, the letter “W” is well identifiable in FIG. 2a. In FIG. 2b, the letter “W” could only be determined in some areas. The contrast is low, especially at the ends of each line and those areas where the lines get close to each other.

[0054] A detailed analysis of the height profile of a smoking article wrapper 1 according to the invention is shown in FIG. 3a-4b. FIG. 3a shows a cut-out of the smoking article wrapper 1 as shown in FIG. 1a in more detail. FIG. 4a shows a cut-out of the smoking article wrapper 1 as shown in FIG. 2b in more detail. At this higher magnification the pattern 10 of the embossing could be clearly recognized for both examples. The lines 11 appear dark in contrast to the non-embossed areas 12. In the non-embossed areas, even single fibres of the base paper could be recognized. Due to the chaotical arrangement of these fibres, the transmitted light in the non-embossed areas 12 is erratic and these areas 12 appear irregularly.

[0055] FIG. 3b shows a diagram illustrating the height profile of the smoking article wrapper 1 as illustrated in FIG. 3a along the indicated path 13. The abscissa indicates the distance (in mm) along the path 13 (of FIG. 3a) and the ordinate the height (in μm) of the smoking article wrapper 1 at the respective point. As it could already be assumed because of the non-uniform opacity, the height of the non-embossed areas 12 of the smoking article wrapper 1 differs along the path 13. However, the height is mostly within a corridor between about 25 μm and 35 μm. The height of the embossed area 11 is much lower. Also, the variation of the height is lower in this area. Thus, the height of the embossed area 12 is mainly within a corridor between about 12 and 14 μm. This also explains the very homogeneous opacity of the embossing as illustrated in FIG. 1a.

[0056] FIG. 4b shows a diagram illustrating the height profile of the smoking article wrapper 1 as illustrated in FIG. 4a along the indicated path 13. Like FIG. 3b, the abscissa indicates the distance (in mm) along the path 13 (of FIG. 4a) and the ordinate the height (in μm) of the smoking article wrapper 1 at the respective point. Compared to the diagram of FIG. 3a, the height of the non-embossed areas 12 is even more irregular. Also, the height of the embossed areas 11 is more irregular. Approximating the height profile of the embossed areas results to a curve profile, having its maximal height in the middle or next to the middle of the respective embossed structure. The height of the non-embossed area 12 is reduced in areas where two embossed areas 11 are close to each other. This could be caused by a compression of the base paper due to the pressure application on both sides of the non-embossed area 12. However, the non-embossed areas 12 are still visible due to its uneven height. In contrast thereto, the smoothness of the embossed areas 11 is higher and the average height lower. However, for the smoking article wrapper 1 as shown in FIG. 4a, the corridors of the height of the embossed areas 11 as well as for the non-embossed areas 12 are wider than those for the smoking article wrapper 1 as shown in FIG. 3a. The corridor of the non-embossed areas extends between about 17 μm and 38 μm and the corridor of the embossed areas extends between about 10 μm and 22 μm. These wider corridors and their partial overlap result in reduced visual and haptical perceptibility of the embossing 10 on the surface of the smoking article wrapper 1. Thus, a product comprising such a smoking article wrapper 1 is usually considered to be less valuable by the consumer and no luxury appearance could be established.

[0057] FIG. 5 illustrate the relation between the porosity of a smoking article wrapper and its surface area covered by an embossed pattern as per FIG. 1 or 2. Since the fibres of a base paper are compressed during and after application of an embossing, pores between the fibres are closed. The portion of closed pores strongly depend from the applied pressure. Furthermore, the pattern of the embossing influences the portion of closed pores. However, as it can be derived from FIG. 5, the influence of the pattern is strongly dependent from the applied pressure.

[0058] The base paper without any embossing has a porosity of about 62 CU. As explained above, this porosity gets lower after application of embossing. The degression of the porosity depends on the applied pressure. After embossing at a pressure of 120 bar (circles) the porosity is greatly reduced. This reduction of porosity is nearly independent from the applied pattern (empty circles (parallel lines) versus filled dots (“W”-pattern)). Based on the measured points a polynomial approximation results in the respective curves (dotted line (parallel lines) vs. solid line (“W”-pattern)). Both curves are very similar and differences in porosity are marginal. This could easily be explained with the assumption that at high pressures all pores of the base paper are closed, independent from the pattern.

[0059] In contrast thereto, the pattern of the embossing has an effect to the porosity if applied at medium high pressure. Based on the measured points (shown as grey empty squares (parallel lines) versus grey filled squares (“W”-pattern)) of the porosity of the smoking article wrapper 1 after application of embossing at 60 bar, polynomial approximation curves were calculated ( - - - (parallel lines) vs. - ⋅ - ⋅ - (“W”-pattern)). The shapes of both curves differ from each other. For both curves (60 bar) the porosity is always higher than for the both curves indicating the trend of the porosity after embossing at 120 bar.

[0060] Furthermore, it is noted that in the figures features are described, which can be advantageous individually. Someone skilled in the art will directly recognize that a specific feature being disclosed in a figure can be advantageous also without the adoption of further features from this figure. Furthermore, someone skilled in the art will recognize that advantages can evolve from a combination of diverse features being disclosed in one or various figures.

LIST OF REFERENCE SYMBOLS

[0061] 1 smoking article wrapper [0062] 10 pattern [0063] 11 embossed surface area [0064] 12 non-embossed surface area [0065] 13 path