Sheathing Paper with Use Indicator for Aerosol-Generating Articles

Abstract

The invention relates to a sheathing paper for aerosol-generating articles, which paper comprises cellulose fibres and onto which paper a composition is applied, which comprises a substance that accelerates the thermal breakdown of cellulose and a binder. Should the mean air permeability of the sheathing paper be 10 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) or more, said composition is merely applied in some regions, which cover at least 0.5% and at most 70% of the area of the sheathing paper.

Claims

1. Wrapping paper for aerosol-generating articles, which comprises pulp fibers, wherein at least 50% of the mass of the wrapping paper is formed by pulp fibers, which has a mean air permeability of at least 0 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) and at most 200 cm.sup.3/(cm.sup.2.Math.min.Math.kPa), measured with a 2 mm×15 mm measuring head in accordance with ISO 2965:2009 at ten randomly selected positions, and to which a composition is applied which comprises a substance accelerating the thermal decomposition of cellulose and a binder, wherein the substance accelerating the thermal decomposition of cellulose is capable of causing an irreversible color change of the wrapping paper due to the thermal decomposition of cellulose in the paper which is discernible by the naked eye upon heating the wrapping paper to a temperature of at least 130° C. for 5 min, wherein, in the case in which the mean air permeability of the wrapping paper is 10 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) or more, said composition is only applied in sections which cover at least 0.5% and at most 70% of the surface of the wrapping paper, and wherein said sections are in this case arranged on the wrapping paper such that furthermore, at least one of the following criteria (1), (2) is fulfilled: (1) if the mean air permeability of the wrapping paper is at least 10 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) and at most 20 cm.sup.3/(cm.sup.2.Math.min.Math.kPa), then the standard deviation of the air permeability is at most 6 cm.sup.3/(cm.sup.2.Math.min.Math.kPa), wherein the standard deviation is determined from ten measurements with said 2 mm×15 mm measuring head on non-overlapping areas located close to each other, and if the mean air permeability of the wrapping paper is at least 20 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) and at most 200 cm.sup.3/(cm.sup.2.Math.min.Math.kPa), then the coefficient of variation of the air permeability is at most 30%, wherein the coefficient of variation is defined as the quotient of said standard deviation and the mean value of the ten measurements from which the standard deviation is determined, (2) the sections to which the composition is applied are shaped such that each imaginary circle with a diameter of D mm on the wrapping paper contains at least one area to which the composition has not been applied, wherein the diameter D in mm is calculated from the mean air permeability x in cm.sup.3/(cm.sup.2.Math.min.Math.kPa) by $D=D_{\max }-\frac{\left(D_{\max }-D_{\min }\right).Math.\left(x-10\right)}{190}\mathrm{wherein}$ $D_{\max }=12\mathrm{mm}\mathrm{and}{D}_{\min }=6\mathrm{mm},$ wherein the mean air permeability x corresponds to said mean value from ten measurements at randomly selected positions on the wrapping paper.

2. Wrapping paper according to claim 1, which has a basis weight of at least 15 g/m.sup.2 and at most 45 g/m.sup.2.

3. (canceled)

4. Wrapping paper according to claim 1, in which the pulp fibers make up at least 60% of the mass of the wrapping paper.

5. (canceled)

6. Wrapping paper according to claim 1, in which at least a portion of the pulp fibers is bleached, wherein the proportion of unbleached pulp fibers is at most 50% of the mass of the pulp fibers.

7. Wrapping paper according to claim 1, which contains one or more fillers, wherein the total amount of filler makes up at least 10% and at most 38% of the mass of the wrapping paper.

8. (canceled)

9. Wrapping paper according to claim 1, which does not contain substances accelerating the decomposition of the cellulose outside the sections to which the composition has been applied, or solely in an amount which does not exceed 0.5% of the mass of the wrapping paper per unit area.

10. Wrapping paper according to claim 1, in which the amount of binder which is applied in sections of the wrapping paper is at most 5% of the mass of the wrapping paper per unit area.

11. (canceled)

12. Wrapping paper according to claim 1, in which the substance accelerating the thermal decomposition of cellulose is contained in an amount of at least 0.2 g/m.sup.2 and at most 8.0 g/m.sup.2 in the areas of the wrapping paper to which the composition containing the same has been applied.

13. Wrapping paper according to claim 1, in which the ratio of the amount of the substance accelerating the thermal decomposition of cellulose in g/m.sup.2 with respect to the area to which the composition containing it has been applied and the amount of pulp fibers in the wrapping paper in g/m.sup.2 is at least 0.05 and at most 0.45.

14. Wrapping paper according to claim 1, wherein the substance accelerating the thermal decomposition of cellulose is one or more of the chemical compounds selected from the group consisting of citrates, malates, tartrates, acetates, nitrates, succinates, fumarates, gluconates, glycolates, lactates, oxylates, salicylates, α-hydroxy caprylates, hydrogen carbonates, carbonates, chlorides, polyphosphates, phosphonates and phosphates.

15. Wrapping paper according to claim 1, wherein, in the case in which the mean air permeability of the wrapping paper is at least 10 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) and at most 200 cm.sup.3/(cm.sup.2.Math.min.Math.kPa), the sections to which said composition is applied are shaped such that they make up at least 1% and at most 60% of the surface of the wrapping paper.

16. Wrapping paper according to claim 1 in which, in the case in which the mean air permeability of the wrapping paper is at least 10 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) and at most 200 cm.sup.3/(cm.sup.2.Math.min.Math.kPa), the sections are shaped such that at least one of the following two criteria (3), (4) is fulfilled: (3) if the mean air permeability of the wrapping paper is greater than 10 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) and less than 20 cm.sup.3/(cm.sup.2.Math.min.Math.kPa), then the standard deviation of the air permeability is at most 5.5 cm.sup.3/(cm.sup.2.Math.min.Math.kPa), and if the mean air permeability of the wrapping paper is at least 20 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) and at most 200 cm.sup.3/(cm.sup.2.Math.min.Math.kPa), then the coefficient of variation of the air permeability is at most 25%, or (4) the sections to which the composition is applied are shaped such that each imaginary circle with a diameter of D mm on the wrapping paper contains at least one area to which the composition is not applied, wherein the diameter D in mm is calculated from the mean air permeability x in cm.sup.3/(cm.sup.2.Math.min.Math.kPa) by $D=D_{\max }-\frac{\left(D_{\max }-D_{\min }\right).Math.\left(x-10\right)}{190}\mathrm{and}\mathrm{wherein}$ $D_{\max }=12\mathrm{mm}\mathrm{and}{D}_{\min }=6\mathrm{mm},$

17. Wrapping paper according to claim 1 in which, in the case in which the mean air permeability of the wrapping paper is at least 0 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) and at most 10 cm.sup.3/(cm.sup.2.Math.min.Math.kPa), the composition is applied to the entire surface or in sections, wherein, in the case of an application in sections, the sections to which the composition is applied to the wrapping paper are shaped such that each imaginary circle with a diameter of 12 mm, on the wrapping paper contains at least one area to which the composition has not been applied.

18. Wrapping paper according to claim 1 in which, in the case in which the mean air permeability of the wrapping paper is at least 0 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) and at most 10 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) and the composition is only applied in sections, the sections to which said composition is applied are shaped such that they make up at least 0.5% and at most 70% of the surface of the wrapping paper.

19. Rod-shaped, aerosol-generating article which comprises an aerosol-generating material and a wrapping paper according to claim 1, wherein the wrapping paper wraps the aerosol-generating material and wherein during the intended use of the aerosol-generating article, the aerosol-generating material is only heated, but not burnt.

20. Rod-shaped, aerosol-generating article according to claim 19, in which during the intended use, the aerosol-generating material is heated to a maximum temperature of at least 120° C. and at most 500° C.

21. Process for manufacturing a wrapping paper for aerosol-generating articles, comprising the steps A to C: A—providing a base wrapping paper, B—applying a composition to the base wrapping paper, and C—drying the wrapping paper obtained in step B, wherein the wrapping paper obtained after step C comprises pulp fibers, wherein at least 50% of the mass of the wrapping paper is formed by pulp fibers, and the wrapping paper obtained after step C has a mean air permeability of at least 0 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) and at most 200 cm.sup.3/(cm.sup.2.Math.min.Math.kPa), measured with a 2 mm×15 mm measuring head in accordance with ISO 2965:2009, and in step B, a composition is applied which comprises a substance accelerating the thermal decomposition of cellulose and a binder, wherein the substance accelerating the thermal decomposition of cellulose is capable of causing an irreversible color change of the wrapping paper due to the thermal decomposition of cellulose in the paper which is discernible by the naked eye upon heating the wrapping paper to a temperature of at least 130° C. for 5 min, and wherein, if the mean air permeability of the wrapping paper obtained in step C is at least 10 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) and at most 200 cm.sup.3/(cm.sup.2.Math.min.Math.kPa), in step B the composition is applied only in sections which cover at least 0.5% and at most 70% of the surface of the wrapping paper, and wherein, if the mean air permeability of the wrapping paper obtained in step C is at least 10 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) and at most 200 cm.sup.3/(cm.sup.2.Math.min.Math.kPa), the wrapping paper obtained in step C fulfills at least one of the following criteria (1), (2): (1) if the mean air permeability of the wrapping paper obtained in step C is at least 10 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) and at most 20 cm.sup.3/(cm.sup.2.Math.min.Math.kPa), then the standard deviation of the air permeability is at most 6 cm.sup.3/(cm.sup.2.Math.min.Math.kPa); and if the mean air permeability of the wrapping paper obtained in step C is at least 20 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) and at most 200 cm.sup.3/(cm.sup.2.Math.min.Math.kPa), then the coefficient of variation of the air permeability is at most 30%, or (2) the sections to which the composition is applied in step B are shaped such that every imaginary circle with a diameter of D mm on the wrapping paper contains at least one area to which the composition is not applied, wherein the diameter D in mm is calculated from the mean air permeability x in cm.sup.3/(cm.sup.2.Math.min.Math.kPa) of the wrapping paper obtained after step C by $D=D_{\max }-\frac{\left(D_{\max }-D_{\min }\right).Math.\left(x-10\right)}{190}\mathrm{and}\mathrm{wherein}$ $D_{\max }=12\mathrm{mm}\mathrm{and}{D}_{\min }=6\mathrm{mm}.$

22. Process according to claim 21, in which the composition applied in step B comprises a substance accelerating the thermal decomposition of cellulose, a binder and a solvent, wherein the solvent is water.

23. (canceled)

24. Process according to claim 21, in which the substance accelerating the thermal decomposition of cellulose contained in the composition of step B is one or more of the chemical compounds selected from the group consisting of citrates, malates, tartrates, acetates, nitrates, succinates, fumarates, gluconates, glycolates, lactates, oxylates, salicylates, α-hydroxy caprylates, hydrogen carbonates, carbonates, chlorides, polyphosphates, phosphonates and phosphates.

25. Process according to claim 21, in which the composition which is applied to the base wrapping paper in step B contains the substance accelerating the thermal decomposition of cellulose in an amount of at least 3% and at most 30% with respect to the mass of the composition.

26. (canceled)

27. Process according to claim 21, in which the composition which is applied to the wrapping paper in step B contains the binder in an amount of at least 0.1% and at most 15% with respect to the amount of composition.

28. Process according to claim 21, in which during drying in step C, a solvent is substantially removed from the composition and the applied dried composition is afterwards present in an amount of at least 0.2 g/m.sup.2 and at most 8 g/m.sup.2 with respect to the area to which the composition was actually applied.

29. Process according to claim 21, in which the application of the composition in step B is carried out by printing or spraying.

30. Process according to one of claim 21, in which the drying process in step C is carried out by contact with one or more heated cylinders, by contact with hot air, by infra-red radiation, microwave radiation or combinations thereof.

31. Process according to claims 21, in which the process comprises further additional steps D and E following step C, wherein in step D, water is applied to the entire surface of the wrapping paper obtained in step C and in step E, the wrapping paper from step D is dried by contact with one or more heated cylinders.

32. Wrapping paper according to claim 9, which does not contain substances accelerating the decomposition of the cellulose outside the sections to which the composition has been applied, or solely in an amount which does not exceed 0.1% of the mass of the wrapping paper per unit area.

33. Wrapping paper according to claim 1, in which the substance accelerating the thermal decomposition of cellulose is contained in an amount of at least 0.5 g/m.sup.2 and at most 5.0 g/m.sup.2 in the areas of the wrapping paper to which the composition containing the same has been applied.

34. Wrapping paper according to claim 1, in which the ratio of the amount of the substance accelerating the thermal decomposition of cellulose in g/m.sup.2 with respect to the area to which the composition containing it has been applied and the amount of pulp fibers in the wrapping paper in g/m.sup.2 is at least 0.07 and at most 0.25.

35. Wrapping paper according to claim 14, wherein the substance accelerating the thermal decomposition of cellulose is one or more of the chemical compounds selected from the group consisting of trisodium citrate, tripotassium citrate, monoammonium phosphate, sodium acetate, potassium acetate, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium carbonate, potassium carbonate, sodium tartrate, potassium sodium tartrate, potassium formate, sodium formate, sodium nitrate and potassium nitrate.

36. Wrapping paper according to claim 1, wherein, in the case in which the mean air permeability of the wrapping paper is at least 10 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) and at most 200 cm.sup.3/(cm.sup.2.Math.min.Math.kPa), the sections to which said composition is applied are shaped such that they make up at least 1% and at most 10% of the surface of the wrapping paper.

37. Wrapping paper according to claim 16, wherein D.sub.max=6 mm and D.sub.min=3 mm.

38. Wrapping material according to claim 18, in which, in the case in which the mean air permeability of the wrapping paper is at least 0 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) and at most 10 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) and the composition is only applied in sections, the sections to which said composition is applied are shaped such that they make up at least 1% and at most 20% of the surface of the wrapping paper.

39. Process according to claim 24, in which the substance accelerating the thermal decomposition of cellulose contained in the composition of step B is one or more of the chemical compounds selected from the group consisting of trisodium citrate, tripotassium citrate, monoammonium phosphate, sodium acetate, potassium acetate, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium carbonate, potassium carbonate, sodium tartrate, potassium sodium tartrate, potassium formate, sodium formate, sodium nitrate and potassium nitrate.

40. Process according to claim 28, in which during drying in step C, a solvent is substantially removed from the composition and the applied dried composition is afterwards present in an amount of at least 1 g/m.sup.2 and at most 5 g/m.sup.2 with respect to the area to which the composition was actually applied.

Description

BRIEF DESCRIPTION OF THE FIGURE

[0078] FIG. 1 shows, by way of example, a wrapping paper and the positions at which the ten measurements for the determination of the standard deviation and the coefficient of variation of the air permeability can be carried out.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0079] In the following, some preferred embodiments of wrapping papers according to the invention are described.

[0080] As the base wrapping paper in step A of the process according to the invention, two papers designated as base wrapping paper A and base wrapping paper B were used.

[0081] Base wrapping paper A had a basis weight of 29 g/m.sup.2 and contained 69% wood pulp fibers and 31% precipitated calcium carbonate as filler. The percentages in this regard refer to the mass of the base wrapping paper. The wood pulp fibers were a mixture of pulp fibers sourced from coniferous trees and deciduous trees. Base wrapping paper A had a mean air permeability of 60.1 cm.sup.3/(cm.sup.2.Math.min.Math.kPa), wherein the air permeability was measured in accordance with ISO 2965:2009 with a measuring head with an opening of 2 mm×15 mm at ten randomly selected positions, and the mean value was calculated from these ten measurements.

[0082] Base wrapping paper B had a basis weight of 24 g/m.sup.2 and contained 71% wood pulp fibers and 29% precipitated calcium carbonate as filler. The percentages in this regard refer to the mass of the base wrapping paper. The wood pulp fibers were a mixture of pulp fibers sourced from coniferous trees and deciduous trees. Base wrapping paper B had a mean air permeability of 74.8 cm.sup.3/(cm.sup.2.Math.min.Math.kPa), wherein the air permeability was measured in accordance with ISO 2965:2009 with a measuring head with an opening of 2 mm×15 mm at ten randomly selected positions, and the mean value was calculated from these ten measurements.

[0083] Different compositions were applied by rotogravure printing to the base wrapping papers A and B in sections in the form of a pattern of crossing lines, 1.5 mm wide, so that the sections to which the composition was applied made up about 40% of the area of the base wrapping paper.

[0084] The amount of composition which was applied in the sections was 30 g/m.sup.2 for base wrapping paper A and 25 g/m.sup.2 for base wrapping paper B with respect to the area to which the composition was actually applied.

[0085] The wrapping papers were then dried in accordance with step C of the process according to the invention.

[0086] The parameters relevant for the manufacture of the wrapping papers are provided in Table 1. The column “No.” indicates the number of the wrapper, the column “BP” indicates which base wrapping paper was used for the manufacture. Under the column “Composition”, the binder and the substance accelerating the thermal decomposition of cellulose are provided as a % with respect to the mass of the composition. The type of the binder is provided, wherein “CMC” means carboxy methyl cellulose and “St” means starch. The type of substance is also provided, wherein “TKZ” means tripotassium citrate, “MAP” means monoammonium phosphate, “NaAc” means sodium acetate and “KCrb” means potassium carbonate. Under the column “Wrapping Paper”, the amount of binder and the substance accelerating the thermal decomposition of cellulose are provided in g/m.sup.2 and as a % with respect to the basis weight of the wrapping paper, as well as the ratio “V” of the amount of said substance in g/m.sup.2 to the amount of pulp fibers in the wrapping paper in g/m.sup.2.

TABLE-US-00001 Composition Wrapping Paper Binder Substance Binder Substance No. BP % Art % Art g/m.sup.2 % g/m.sup.2 % V  1 A 0.71 CMC  5.0 TKZ 0.21 0.69 1.50  4.88 0.07  2 A 0.68 CMC  8.7 TKZ 0.20 0.64 2.61  8.20 0.13  3 A 0.70 CMC 10.0 TKZ 0.21 0.65 3.00  9.31 0.15  4 A 0.65 CMC 12.0 TKZ 0.20 0.59 3.60 10.98 0.18  5 A 0.63 CMC 14.8 TKZ 0.19 0.56 4.44 13.20 0.22  6 A 0.71 CMC  5.0 MAP 0.21 0.69 1.50  4.88 0.07  7 A 0.68 CMC  8.7 MAP 0.20 0.64 2.61  8.20 0.13  8 A 0.70 CMC 10.0 MAP 0.21 0.65 3.00  9.31 0.15  9 A 0.65 CMC 12.0 MAP 0.20 0.59 3.60 10.98 0.18 10 A 0.63 CMC 14.8 MAP 0.19 0.56 4.44 13.20 0.22 11 A 0.70 CMC  5.0 NaAc 0.21 0.68 1.50  4.88 0.07 12 A 0.70 CMC 10.0 NaAc 0.21 0.65 3.00  9.31 0.15 13 B 0.75 CMC 10.0 KCrb 0.19 0.70 2.50  9.37 0.15 14 B 0.75 CMC 25.0 KCrb 0.19 0.62 6.25 20.53 0.37 15 B 0.70 CMC 30.0 KCrb 0.18 0.55 7.50 23.68 0.44 16 B 5.00 St  8.0 KCrb 1.25 4.59 2.00  7.34 0.12 17 B 5.00 St 25.0 KCrb 1.25 3.97 6.25 19.84 0.37 18 B 5.00 CMC 25.0 KCrb 1.25 3.97 6.25 19.84 0.37

[0087] As for the base wrapping papers A and B the air permeability was measured at ten randomly selected positions in accordance with ISO 2965:2009 with a measuring head with an opening of 2 mm×15 mm and the mean value was calculated therefrom. For the wrapping papers 1 to 12, which were manufactured from base wrapping paper A, a mean air permeability between 42 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) and 48 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) was found, while the mean air permeability of the wrapping papers 13 to 18, which were manufactured from base wrapping paper B, was between 50 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) and 55 cm.sup.3/(cm.sup.2.Math.min.Math.kPa).

[0088] For the test of the criteria (1) or (3), the coefficient of variation of the air permeability was determined in accordance with ISO 2965:2009 with a measuring head with an opening of 2 mm×15 mm. The measurement method is explained with reference to FIG. 1. With the wrapping paper 1 in FIG. 1, the composition is applied in the shape of crossing lines 2 and the measuring head with an opening of 2 mm×15 mm was placed at ten positions 3a to 3j next to each other, wherein the individual positions were each shifted by 3 mm, so that a distance of 1 mm was between the areas. The air permeability was measured on each of the positions 3a to 3j. From that, the mean value and the standard deviation were determined and the coefficient of variation was calculated. For the wrapping papers 1 to 12 which were manufactured from base wrapping paper A, coefficients of variation of between 10% and 15% were obtained and for the wrapping papers 13 to 18 which were manufactured from base wrapping paper B, the coefficients of variation were between 12% and 17%, so that the criteria (1) and (3) are fulfilled.

[0089] For the test of criteria (2) and (4), the diameter of the imaginary circle was determined for each of the wrapping papers 1 to 18 based on the measured mean air permeability.

[0090] For the wrapping papers 1 to 12, which were manufactured from base wrapping paper A, based on a mean air permeability of 42 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) to 48 cm.sup.3/(cm.sup.2.Math.min.Math.kPa), the result was a diameter of the circle from

[00005]$D=12-\frac{\left(12-6\right).Math.\left(42-10\right)}{190}=11.0\mathrm{mm}$$\mathrm{to}$$D=12-\frac{\left(12-6\right).Math.\left(48-10\right)}{190}=10.8\mathrm{mm}$

[0091] For the wrapping papers 13 to 18 which were manufactured from base wrapping paper B, based on a mean air permeability of 50 cm.sup.3/(cm.sup.2.Math.min.Math.kPa) to 55 cm.sup.3/(cm.sup.2.Math.min.Math.kPa), the result was a diameter of the circle from

[00006]$D=12-\frac{\left(12-6\right).Math.\left(50-10\right)}{190}=10.7\mathrm{mm}$$\mathrm{to}$$D=12-\frac{\left(12-6\right).Math.\left(55-10\right)}{190}=10.6\mathrm{mm}$

[0092] The pattern with 1.5 mm wide crossing lines obviously fulfills the requirements of criteria (2) and (4) and thus these criteria are fulfilled for all wrapping papers 1 to 18.

[0093] The wrapping papers 1 to 18 were heated to 130° C. for 5 minutes. After just one minute, a change in color was discernible on the wrapping papers 1, 3, 6, 8, 11, 12, 13 and 17. After 5 minutes, all of the wrapping papers according to the invention showed a significant, irreversible color change to yellowish colors in the sections to which the composition was applied, and for longer periods of heating to light brown to dark brown colors, which can be clearly discerned from the unchanged or hardly changed color outside of these sections.

[0094] Aerosol-generating articles according to the prior art were manufactured from the wrapping papers which were heated in a heating device, as intended. After removing the aerosol-generating articles from the heating device, a distinct color change could be discerned in the printed sections, so that used and unused aerosol-generating articles were clearly discernible from each other.