FILTER MATERIAL FOR SMOKING ARTICLES HAVING IMPROVED EXPANSION BEHAVIOUR

Abstract

Shown is a filter material for manufacturing a segment for a smoking article, wherein the filter material is web-shaped and contains at least 50% and at most 100% cellulose fibers, each with respect to the mass of the filter material, wherein the filter material has a basis weight of at least 15 g/m.sup.2 and at most 60 g/m.sup.2, wherein the thickness of one layer of the filter material, measured in accordance with ISO 534:2011, is at least 25 m and at most 1000 m, wherein the filter material has a machine direction and a cross direction orthogonal thereto and lying in the plane of the web of the filter material, and wherein the filter material has a characteristic plastic deformability in the cross direction which is characterized in that in a tensile test in the cross direction in accordance with ISO 1924-2:2008, the nonlinear portion of the deformation energy absorbed by the filter material up to half the elongation at break is at least 10% and at most 50% of the total deformation energy absorbed by the filter material up to half the elongation at break.

Claims

1. Filter material for manufacturing a segment for a smoking article, wherein the filter material is web-shaped and contains at least 50% and at most 100% cellulose fibers, each with respect to the mass of the filter material, wherein the filter material has a basis weight of at least 15 g/m.sup.2 and at most 60 g/m.sup.2, wherein the thickness of one layer of the filter material, measured in accordance with ISO 534:2011, is at least 25 m and at most 1000 m, wherein the filter material has a machine direction and a cross direction orthogonal thereto and lying in the plane of the web of the filter material, and wherein the filter material has a characteristic plastic deformability in the cross direction which is characterized in that in a tensile test in the cross direction in accordance with ISO 1924-2:2008, the nonlinear portion of the deformation energy absorbed by the filter material up to half the elongation at break is at least 10% and at most 50% of the total deformation energy absorbed by the filter material up to half the elongation at break.

2. Filter material according to claim 1, in which the filter material is a hydroentangled nonwoven or a paper.

3. Filter material according to claim 1, in which the proportion of cellulose fibers in the filter material is at least 70% and at most 95%, each with respect to the mass of the filter material.

4. Filter material according to claim 1, in which the cellulose fibers are formed by pulp fibers or fibers from regenerated cellulose or mixtures thereof.

5. (canceled)

6. Filter material according to claim 4, in which the proportion of fibers produced from regenerated cellulose is at least 5% and at most 50% with respect to the mass of the filter material.

7. (canceled)

8. Filter material according to claim 1, with a basis weight of at least 20 g/m.sup.2 and at most 50 g/m.sup.2.

9. Filter material according to claim 1, wherein the filter material has a characteristic plastic deformability in the cross direction which is characterized in that in said tensile test in the cross direction in accordance with ISO 1924-2:2008, the nonlinear portion of the deformation energy absorbed by the filter material up to half the elongation at break is at least 18% and at most 32% of the total deformation energy absorbed by the filter material up to half the elongation at break.

10. (canceled)

11. (canceled)

12. Filter material according to claim 1, which contains at least one substance selected from the group consisting of triacetin, propylene glycol, sorbitol, glycerol, polyethylene glycol, polypropylene glycol, polyvinyl alcohol and triethyl citrate, or a mixture of two or more of the at least one substances.

13. Filter material according to claim 1, in which at least a portion of the cellulose fibers is loaded with a filler, wherein the filler is formed by calcium carbonate particles.

14. Filter material according to claim 1, in which the thickness of one layer of the filter material, measured in accordance with ISO 534:2011, is least 35 m and at most 600 m.

15. (canceled)

16. (canceled)

17. Segment for a smoking article, comprising a filter material gathered in the cross direction, wherein the filter material contains at least 50% and at most 100% cellulose fibers, each with respect to the mass of the filter material, wherein the filter material has a basis weight of at least 15 g/m.sup.2 and at most 60 g/m.sup.2, wherein the thickness of one layer of the filter material, measured in accordance with ISO 534:2011, is at least 25 m and at most 1000 m, wherein the filter material has a cross direction, in which the filter material is gathered, and wherein the filter material in the non-gathered state has a characteristic plastic deformability in the cross direction which is characterized in that in a tensile test in the cross direction in accordance with ISO 1924-2:2008, the nonlinear portion of the deformation energy absorbed by the filter material up to half the elongation at break is at least 10% and at most 50% of the total deformation energy absorbed by the filter material up to half the elongation at break.

18. Segment according to claim 17, in which the filter material has one or more of the features that are defined in claim 2.

19. Segment according to claim 17, wherein the segment is cylindrical with a diameter of at least 4 mm and at most 9 mm, and/or wherein the segment has a length of at least 6 mm and at most 35 mm.

20. Segment according to claim 17, wherein the draw resistance of the segment in accordance with ISO 6565:2015 per unit length of the segment is at least 1 mmWG/mm and at most 12 mmWG/mm.

21. (canceled)

22. Segment according to claim 17, wherein the wrapper material has a basis weight in accordance with ISO 536:2019 of at least 30 g/m.sup.2 and at most 130 g/m.sup.2.

23. Process for manufacturing a segment according to claim 17, in which the filter material according to claim 1 is crimped or pleated, a continuous tow of crimped or pleated filter material is formed and the tow of crimped or pleated filter material is wrapped with a wrapper material and the wrapped tow is cut into individual rods of a defined length.

24. Smoking article, comprising a segment, which contains an aerosol-forming material, and a segment according to claim 17.

25. Smoking article according to claim 24, wherein the smoking article is a filter cigarette, and the aerosol-forming material is or contains tobacco.

26. Smoking article according to claim 24, wherein the smoking article is a smoking article in which, during its intended use, the aerosol-forming material is only heated but not burned, wherein the aerosol-forming material comprises a material which is selected from the group consisting of tobacco, reconstituted tobacco, nicotine, glycerol, propylene glycol or mixtures thereof.

27. Smoking article according to claim 26, in which the aerosol-forming material is present in liquid form and located in a corresponding container in the smoking article.

28. Process for manufacturing a filter material, wherein the process comprises the following steps: A1providing a fiber web comprising cellulose fibers, which has a machine direction and a cross direction orthogonal thereto and lying in the web plane, A2hydroentangling the fiber web by water jets directed onto the fiber web to produce a hydroentangled fiber web, A3drying the hydroentangled fiber web, wherein in step A1, the amount or the proportion of cellulose fibers in the fiber web is selected such that after drying in step A3, the filter material contains at least 50% and at most 100% cellulose fibers, with respect to the mass of the filter material, and wherein in step A2, the number, pressure and/or arrangement of the water jets is selected such that the filter material is provided with a characteristic plastic deformability in the cross direction, which is characterized in that in a tensile test carried out on the filter material after drying in step A3 in the cross direction in accordance with ISO 1924-2:2008, the nonlinear portion of the deformation energy absorbed by the filter material up to half the elongation at break is at least 10% and at most 50% of the total deformation energy absorbed by the filter material up to half the elongation at break, wherein, after drying in step A3, the filter material has a basis weight of at least 15 g/m.sup.2 and at most 60 g/m.sup.2, and wherein the thickness of one layer of the filter material, measured in accordance with ISO 534:2011, after drying in step A3, is at least 25 m and at most 1000 m.

29. (canceled)

30. Process according to claim 28, in which the hydroentangling in step A2 is carried out by at least two rows of water jets directed onto the fiber web, wherein the water jets act on each of the two sides of the fiber web.

31. Process for manufacturing a filter material, which comprises the following steps B1 to B4: B1producing an aqueous suspension comprising cellulose fibers, B2applying the suspension from step B1 to a running wire, B3de-watering the suspension through the running wire to form a fiber web, B4drying the fiber web from step B3, wherein in step B1, the amount or the proportion of cellulose fibers is selected such that after drying in step B4, the filter material contains at least 50% and at most 100% cellulose fibers, with respect to the mass of the filter material, wherein a machine direction of the fiber web is defined by the running direction of the wire in step B3 and a cross direction is defined by a direction orthogonal thereto and lying in the plane of the fiber web, and wherein in step B2, the suspension is applied to the running wire with a speed which is lower than the speed of the running wire and the difference between these speeds is selected such that the filter material is provided with a characteristic plastic deformability in the cross direction, which is characterized in that in a tensile test carried out on after drying in step B4, the filter material in the cross direction in accordance with ISO 1924-2:2008, the nonlinear portion of the deformation energy absorbed by the filter material up to half the elongation at break is at least 10% and at most 50% of the total deformation energy absorbed by the filter material up to half the elongation at break, wherein, after drying in step B4, the filter material has a basis weight of at least 15 g/m.sup.2 and at most 60 g/m.sup.2, and wherein the thickness of one layer of the filter material, measured in accordance with ISO 534:2011, after drying in step B4, is at least 25 m and at most 1000 m.

32. Process for manufacturing a filter material, which comprises the following steps C1 to C6: C1producing an aqueous suspension comprising cellulose fibers, C2applying the suspension from step C1 to a running wire, C3de-watering the suspension through the running wire, to form a fiber web, C4transferring the fiber web from step C3 to a support wire, C5hydroentangling the fiber web by water jets directed onto the fiber web to form a hydroentangled fiber web, C6drying the hydroentangled fiber web, wherein, in step C1, the amount or the proportion of cellulose fibers is selected such that after drying in step C6, the filter material contains at least 50% and at most 100% cellulose fibers, with respect to the mass of the filter material, and wherein in step C3, a machine direction of the fiber web is defined by the running direction of the wire and a cross direction is defined by a direction orthogonal thereto and lying in the plane of the fiber web, wherein, after drying in step C6, the filter material has a basis weight of at least 15 g/m.sup.2 and at most 60 g/m.sup.2, and wherein the thickness of one layer of the filter material, measured in accordance with ISO 534:2011, after drying in step C6, is at least 25 m and at most 1000 m, wherein in step C2, the suspension is applied to the running wire with a speed which is lower than the speed of the running wire and the difference between these speeds in step C2 and the number, pressure and/or arrangement of the water jets in step C5 are selected such that the filter material is provided with a characteristic plastic deformability in the cross direction, which is characterized in that in a tensile test carried out on after drying in step C6, the filter material in the cross direction in accordance with ISO 1924-2:2008, the nonlinear portion of the deformation energy absorbed by the filter material up to half the elongation at break is at least 10% and at most 50% of the total deformation energy absorbed by the filter material up to half the elongation at break.

33. Process according to claim 31, in which the aqueous suspension in step B1 or C1, respectively, has a solids content of at most 0.2%.

34. (canceled)

35. (canceled)

36. (canceled)

37. Process according to claim 28, wherein the filter material manufactured according to this process is a filter material according to claim 1.

38. Process according to claim 28, which comprises a further step, in which one or more additives are applied onto the fiber web, wherein the one or more additives is or are selected from the group consisting of alkyl ketene dimers (AKD), acid anhydrides, alkenyl succinic acid anhydride (ASA), polyvinyl alcohol, waxes, fatty acids, starch, starch derivatives, carboxy methyl cellulose, alginates, chitosan, wet strength agents or substances to adjust the pH, organic or inorganic acids or bases, and mixtures thereof.

39. (canceled)

40. Process according to claim 38, in which the one or more additives is or are applied between the steps A2 and A3, or between the steps B3 and B4, or between the steps C3 and C4 or C4 and C5 or C5 and C6, or wherein the one or more additives are applied after the step A3, or after the step B4, or after the step C6, followed by a further step of drying the fiber web.

41. Smoking article according to claim 24, wherein said segment according to claim 17 is the segment of the smoking article located closest to the mouth end.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0118] FIG. 1 shows, by way of example, a force-elongation-diagram of a filter material according to the invention.

[0119] FIG. 2 shows, by way of example, a force-elongation-diagram of a filter material not according to the invention.

[0120] FIG. 3 shows a device, by means of which the third process according to the invention for manufacturing a filter material according to the invention can be carried out.

[0121] FIG. 4 shows force-elongation-curves measured in the cross direction on embodiments A, B and C according to the invention.

[0122] FIG. 5 shows force-elongation-curves measured in the cross direction on comparative example Z, not according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS AND A COMPARATIVE EXAMPLE

[0123] Some preferred embodiments of the filter material, of the processes for manufacturing the filter material, of the segment for smoking articles and of the smoking article are described below. Further, a comparative example not according to the invention is described.

Exemplary Embodiments A, B and C

[0124] The device shown in FIG. 3 was used to manufacture the embodiments A, B and C according to the invention.

[0125] A suspension 31 from pulp fibers and fibers from regenerated cellulose was provided in a storage tank 32, step C1, and from there was pumped to a running wire 33, inclined upwards relative to the horizontal, step C2, and was de-watered by vacuum boxes 39, step C3, so that a fiber web 34 was formed on the wire, the general direction of movement of which is indicated by arrow 310. In this regard, the speed at which the wire 33 moved was selected to be about 10% higher than the speed of the suspension 31 flowing from the storage tank 32, in order to orient the fibers primarily in the machine direction. The fiber web 34 was taken off the wire 33 and transferred to a running support wire 35 which was also running, step C4. There, from devices 36, water jets 311 arranged in several rows transverse to the machine direction of the fiber web 34 were directed onto the fiber web 34 to entangle the fibers and to consolidate the fiber web 34 into a nonwoven, step C5. In continuation of step C5, water jets 312 were also directed onto the other side of the fiber web 34 by additional devices 37. Then the still-moist nonwoven ran through a drying unit 38 and was dried there, step C6, to obtain the filter material.

[0126] To manufacture the filter material, a mixture of pulp fibers produced from coniferous woods and Lyocell fibers was used, wherein the amount of fibers was selected such that the finished filter material consisted of 65% pulp fibers and 35% Lyocell fibers. The finished filter material had a basis weight, in accordance with ISO 536:2019, of 55 g/m.sup.2.

[0127] In step C5 of the manufacturing process, firstly, water jets in three rows, 311 in FIG. 3, were directed onto the first side of the fiber web 34 and then water jets in one row, 312 in FIG. 3, were directed onto the second side of the fiber web 34. The pressure of the water jets here was varied between 2 MPa and 40 MPa in three steps (low, medium, high), in order to obtain different filter materials according to the invention A, B and C. The diameter of the openings from which the water jets exited was different between the rows and was selected to be between 80 m and 120 m; the distance of the openings from center to center was 0.3 mm.

[0128] Samples were taken in the cross direction from these filter materials and the force-elongation-diagram was recorded in a tensile test in accordance with ISO 1924-2:2008. The result is shown in FIG. 4. On the x-axis 40, the elongation in % is shown, while on the y-axis 41, the force in N is shown. The three lines designated by A, B and C show the force-elongation diagrams of the three filter materials according to the invention A, B and C. By way of example, the determination of the nonlinear portion of the deformation energy absorbed up to half the elongation at break with respect to the total deformation energy absorbed up to half the elongation at break is explained for filter material C.

[0129] At the half elongation at break .sub.b/2, the corresponding force F(.sub.b/2) is determined and the linear portion of the deformation energy E.sub.lin a can be calculated therefrom by

[00005]$E_{\mathrm{lin}}=\frac{1}{4}F\left(\frac{{}_b}{2}\right){}_b.$

[0130] The total deformation energy absorbed up to half the elongation at break corresponds to the area spanned by the x-axis 40 and curve C from =0 to =.sub.b/2 and can be determined with sufficient accuracy by methods of numerical integration without problems. If the linear portion of the deformation energy E.sub.lin is subtracted therefrom, the hatched area remains, which corresponds to the nonlinear portion of the deformation energy E.sub.nl.

[0131] The determination of the deformation energies up to half the elongation at break was carried out for all filter materials A, B and C and the results are shown in Table 1, wherein E is the total deformation energy, E.sub.lin is the linear portion of the deformation energy, and E.sub.nl is the nonlinear portion of the deformation energy, each in the cross direction up to half the elongation at break. The deformation energies were determined numerically from the force-elongation-curves and thus formally have the unit N-%. In order to reach the usual unit of J/m.sup.2, the sample geometry needs to be considered. Since only the proportions relative to each other are important here, and since the sample geometries are identical, this was not done. The elongation at break .sub.b and the force at half the elongation at break F(.sub.b/2) are also shown.

TABLE-US-00001 TABLE 1 Ex Pressure .sub.b [%] F(.sub.b/2) [N] E E.sub.lin E.sub.nl E.sub.nl/E [%] A Low 43.0 4.28 59.3 46.0 13.3 22.4 B Medium 40.8 3.92 55.3 40.0 15.3 27.7 C High 32.4 3.24 34.1 26.2 7.9 23.0

[0132] The values from Table 1 show that for the embodiments according to the invention A, B and C, the nonlinear portion of the deformation energy is about 20% to about 30%. It is also noticeable that with increasing pressure of the water jets, the elongation at break decreases. For this reason, it can be of advantage to select a lower pressure for the water jets, because apart from the good plastic elongation behavior, then larger permanent deformations are also possible during crimping.

Exemplary Embodiment D

[0133] To manufacture the exemplary embodiment according to the invention D, the second process according to the invention, comprising the steps B1 to B4, was selected.

[0134] To manufacture the filter material, a mixture of pulp fibers from coniferous woods and Lyocell fibers was used, wherein the amount of fibers was selected such that the finished filter material consisted of 80% pulp fibers and 20% Lyocell fibers. The finished filter material had a basis weight, in accordance with ISO 536:2019, of 15 g/m.sup.2.

[0135] In step B2 of the process according to the invention the speed of the suspension flowing out was selected to be about 10% lower than the speed of the running wire.

[0136] Four samples in the cross direction were taken from the filter material D obtained thereby and the force-elongation-diagram was recorded in a tensile test in accordance with ISO 1924-2:2008. The evaluation of the force-elongation-diagrams was carried out analogously to the embodiments A, B and C. The results of the four measurements are shown in Table 2.

TABLE-US-00002 TABLE 2 Ex. .sub.b [%] F(.sub.b/2) [N] E E.sub.lin E.sub.nl E.sub.nl/E [%] D 4.20 5.97 9.19 6.27 2.92 31.8 D 3.13 5.43 5.91 4.25 1.66 28.1 D 3.56 5.79 7.39 5.15 2.24 30.3 D 4.08 5.90 8.55 6.02 2.53 29.6

[0137] The values from Table 2 show that the filter material according to the invention D has a nonlinear portion of the deformation energy of about 30% and that repeated measurements on the same sample material have a low variance. This proves that the steps B1 to B3 indeed contribute to the desired plastic deformability in the cross direction when the suspension in step B2 is applied to the running wire with reduced speed.

Exemplary Embodiment E

[0138] On the other hand, the special execution of step C2 (with reduced speed of the suspension) used in the exemplary embodiments A, B and C is not needed in order to obtain the characteristic plastic deformability in the cross direction according to the invention in the hydroentangled nonwoven. This can be seen from the exemplary embodiment E described below. To manufacture the exemplary embodiment according to the invention E, the first process according to the invention comprising the steps A1 to A3 was used.

[0139] To manufacture the filter material in embodiment E, a mixture of pulp fibers from coniferous woods and Lyocell fibers was used, wherein the amount of fibers was selected such that the finished filter material consisted of 80% pulp fibers and 20% Lyocell fibers. Step A1 was carried out without providing the pulp fibers in the fiber web with a preferred direction transverse to the machine direction by a reduced speed of application of the suspension as in steps B2 or C2, respectively, of the second or third process. The finished filter material had a basis weight, in accordance with ISO 536:2019, of 15 g/m.sup.2.

[0140] Hydroentanglement step A2 was carried out in the same manner as step C5 of exemplary embodiment B.

[0141] Two samples in the cross direction were taken from the filter material E obtained thereby and the force-elongation-diagram was recorded in a tensile test in accordance with ISO 1924-2:2008. The evaluation of the force-elongation-diagrams was carried out analogously to the embodiments A to C. The results of the two measurements are shown in Table 3.

TABLE-US-00003 TABLE 3 Ex. .sub.b [%] F(.sub.b/2) [N] E E.sub.lin E.sub.nl E.sub.nl/E [%] E 3.26 2.75 3.01 2.47 0.53 17.72 E 3.95 2.85 3.42 2.82 0.59 17.37

[0142] The values from Table 3 show that the filter material E manufactured according to the first process according to the invention has a proportion of the nonlinear deformation energy of about 17%. A comparison with embodiments A to C, which were manufactured by means of a combination of suitable execution of the hydroentangling in step C5 and a pre-structuring of the fiber web by reduced application speed in step C2, i.e. a combination of the first and the second process according to the invention, shows that this combination provides larger proportions of the nonlinear deformation energy of about 22% to about 28%, and can thus lead to a better performance during crimping. The effort of the combined process is, of course, slightly higher than that of the first process alone, i.e. if, as in embodiment E, the characteristic plastic deformability in the cross direction is only obtained by suitable execution of the hydroentangling in step A2. Embodiment E demonstrates that with this simpler process too, filter materials according to the invention can be manufactured.

Comparative Example Z

[0143] To manufacture a filter material not according to the invention, the same mixture of fibers was used as in exemplary embodiment D. The basis weight was still 15 g/m.sup.2, but only machine settings that are common for manufacturing filter papers were used.

[0144] Three samples in the cross direction were taken from the filter material of comparative example Z and the force-elongation-diagram was recorded in a tensile test in accordance with ISO 1924-2:2008. The evaluation of the force-elongation-diagrams was carried out analogously to the embodiments A to C. The results of the three measurements are shown in Table 4.

TABLE-US-00004 TABLE 4 Ex. .sub.b [%] F(.sub.b/2) [N] E E.sub.lin E.sub.nl E.sub.nl/E [%] Z 3.21 8.38 7.22 6.71 0.52 7.17 Z 3.23 7.42 6.40 5.97 0.42 6.64 Z 3.15 7.10 5.89 5.58 0.32 5.38

[0145] The force-elongation-curves of comparative example Z are shown in FIG. 5. Even without a quantitative analysis, it is already clear that the behavior is substantially closer to a linear elastic behavior, so that deformations upon removal of the load are essentially reversed and much higher elongations and forces are required to achieve permanent deformations. This means that the tensile strength or the elongation at break in the cross direction can easily be exceeded.

Manufacture of Segments and Smoking Articles

[0146] Filter rods wrapped with paper with a length of 100 mm and a diameter of 7.85 mm were manufactured from each filter material of exemplary embodiments A to E and the comparative example Z. The width of the filter material and the machine settings during filter manufacture were selected such that a draw resistance of 45010 mmWG resulted.

[0147] Filter rods could be manufactured from the filter materials of exemplary embodiments A to E and the comparative example Z. But during manufacture, it was found that for the filter materials of exemplary embodiments A to E, the process of crimping reacted substantially less sensitively to changes in the machine settings and in particular to the setting of the distance between the rolls during crimping than for comparative example Z.

[0148] Filter cigarettes were manufactured from the segments of the embodiments A to E and the comparative example Z using a common process from the prior art. This manufacturing process was without any problems.

[0149] Thus, it can be seen that segments and smoking articles can be manufactured from the filter material according to the invention more reliably and more easily than from common hydroentangled nonwovens or papers, and that better results can be achieved during crimping due to the advantageous plastic elongation behavior.