FILTER MATERIAL FOR SEGMENTS FOR SMOKING ARTICLES WITH REDUCED CREEP TENDENCY

Abstract

Shown is a filter material for manufacturing a segment for a smoking article, wherein the filter material is hydroentangled 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 400 ?m, and wherein the filter material has a creep tendency in the thickness direction of at most 10%, wherein the creep tendency is the relative decrease in the thickness of 5 layers of the filter material, measured in accordance with ISO 534:2011, within 20 s after the start of the thickness measurement.

Claims

1. Filter material for manufacturing a segment for a smoking article, wherein the filter material is hydroentangled 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 400 ?m, and wherein the filter material has a creep tendency in the thickness direction of at most 10%, wherein the creep tendency is the relative decrease in the thickness of 5 layers of the filter material, measured in accordance with ISO 534:2011, within 20 s after the start of the thickness measurement.

2. 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.

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

4. (canceled)

5. Filter material according to claim 3, in which the proportion of fibers from regenerated cellulose is at least 5% and at most 50% with respect to the mass of the filter material.

6. (canceled)

7. 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.

8. Filter material according to claim 1, wherein the filter material has a creep tendency in the thickness direction of at least 1% and at most 5%.

9. (canceled)

10. (canceled)

11. 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.

12. 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.

13. 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 at least 30 ?m and at most 350 ?m.

14. (canceled)

15. (canceled)

16. Segment for a smoking article, comprising a filter material and a wrapper material, 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 400 ?m, and wherein the filter material has a creep tendency in the thickness direction of at most 10%, wherein the creep tendency is the relative reduction of thickness of 5 layers of the filter material, measured in accordance with ISO 534:2011, within 20 s after the start of the thickness measurement.

17. Segment according to claim 16, in which the filter material has one or more of the additional features that are defined in claim 2.

18. Segment according to claim 16, 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.

19. Segment according to claim 16, 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.

20. (canceled)

21. Segment according to claim 16, in which 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.

22. Process for manufacturing a segment according to claim 16, 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.

23. Smoking article comprising a segment which contains an aerosol-forming material, and a segment according to claim 16.

24. Smoking article according to claim 23, wherein the smoking article is a filter cigarette and the aerosol-forming material is or contains tobacco.

25. Smoking article according to claim 23, 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 selected from the group consisting of tobacco, reconstituted tobacco, nicotine, glycerol, propylene glycol or mixtures thereof.

26. Smoking article according to claim 25, wherein the aerosol-forming material is present in liquid form and located in a corresponding container in the smoking article.

27. Process for manufacturing a filter material, wherein the process comprises the following steps: Aproviding a fiber web comprising cellulose fibers, Bhydroentangling the fiber web by water jets directed onto the fiber web, in order to manufacture a hydroentangled fiber web, Cdrying the hydroentangled fiber web, wherein in step A, the amount or the proportion of cellulose fibers is selected such that after drying in step C, 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 B, the number of water jets, the pressure of the water jets or the shape of the openings from which the water jets exit are chosen such that after drying in step C, the filter material has a creep tendency in the thickness direction of at most 10%, wherein the creep tendency is the relative decrease in the thickness of 5 layers of the filter material, measured in accordance with ISO 534:2011, within 20 s after the start of the thickness measurement, and after drying in step C, the filter material has a basis weight of at least 15 g/m.sup.2 and at most 60 g/m.sup.2 and the thickness of one layer of the filter material, measured in accordance with ISO 534:2011, is at least 25 ?m and at most 400 ?m.

28. Process according to claim 27, in which at least a portion of the nozzles, from which the water jets exit in step B is shaped as round holes in a nozzle strip, wherein the diameter of the holes in the nozzle strip facing the filter material is greater than the diameter of the holes facing away from the filter material and at most twice the diameter of the holes facing away from the filter material.

29. Process according to of claim 27, wherein the filter material manufactured according to this process is a filter material according to claim 1.

30. Process according to claim 27, in which the provision of a fiber web in step A comprises spinning a plurality of cellulose fibers, wherein the cellulose fibers are formed by filaments of regenerated cellulose and wherein at least 90% of the mass of the filter material after drying in step C is formed by the filaments of regenerated cellulose.

31. Process according to claim 27, in which the provision of a fiber web in step A comprises the following steps A1 to A4: A1producing an aqueous suspension comprising cellulose fibers, A2applying the suspension from step A1 to a running wire, A3de-watering the suspension through the running wire to form a fiber web, A4transferring the fiber web from step A3 onto a support wire.

32. Process according to claim 31, in which the aqueous suspension in step A1 has a solids content of at most 0.2%.

33. (canceled)

34. (canceled)

35. (canceled)

36. Process according to claim 35, in which the hydroentangling in step B is carried out by at least four rows of water jets directed onto the fiber web, wherein at least two rows of water jets act on each of the two sides of the fiber web.

37. Process according to of claim 27, which comprises a further step in which one or more additives are applied to 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 anhydrides (ASA), polyvinyl alcohol, waxes, fatty acids, starch, starch derivatives, carboxy methyl cellulose, alginates, chitosan, wet strength agents and substances for adjusting the pH, organic or inorganic acids or bases, and mixtures thereof.

38. (canceled)

39. Process according to claim 27, in which the one or more additives are applied between the steps B and C, or after step C, followed by a further step of drying the fiber web.

40. (canceled)

41. A smoking article of claim 23, wherein said segment according to claim 16 is the segment of the smoking article located closest to the mouth end.

Description

BRIEF DESCRIPTION OF THE FIGURE

[0073] FIG. 1 shows a device with which the process according to the invention for manufacturing the filter material according to the invention can be carried out.

DESCRIPTION OF THE PREFERRED EXEMPLARY EMBODIMENTS AND OF A COMPARATIVE EXAMPLE

[0074] Some preferred embodiments of the filter material, of the process for manufacturing the filter material, of the segment for smoking articles and of the smoking article are described below. Furthermore, a comparative example which is not in accordance with the invention is described.

[0075] The device shown in FIG. 1 was used to manufacture the filter material.

[0076] A suspension 1 of pulp fibers and fibers of regenerated cellulose was provided in a storage tank 2, step A1, and was pumped from there to a running wire 3, inclined upwards relative to the horizontal, step A2, and was de-watered through vacuum boxes 9, step A3, so that a fiber web 4 was formed on the wire, the general direction of movement of which is indicated by the arrow 10. The fiber web 4 was taken off the wire 3 and transferred onto a support wire 5 which was also running, step A4. There, water jets 11 arranged in several rows transverse to the running direction of the fiber web 4 from devices 6 were directed onto the fiber web 4 to entangle the fibers and to consolidate the fiber web 4 to form a nonwoven, step B. In continuation of step B, water jets 12 were also directed onto the other side of the fiber web 4 by additional devices 7. Then the still-moist nonwoven ran through a drying unit 8 and was dried, step C, in order to obtain the filter material.

Exemplary Embodiments

[0077] To manufacture the hydroentangled 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 80% pulp fibers and 20% Lyocell? fibers. The finished filter material had a basis weight, in accordance with ISO 536:2019, of 25 g/m.sup.2.

[0078] In step B of the manufacturing process, firstly, water jets in three rows, 11 in FIG. 1, were directed onto the first side of the fiber web 4 and then water jets in two rows, 12 in FIG. 1, were directed onto the second side of the fiber web. In this regard, the pressure of the water jets in the first three rows was varied between about 3 MPa and about 8 MPa in three steps (low, medium, high), in order to obtain different filter materials according to the invention A, B and C.

[0079] The creep tendency in the thickness direction was determined in conformity with ISO 534:2011 for these filter materials. In this regard, 5 layers of the filter material were stacked one upon the other and the measurement of the thickness in accordance with ISO 534:23011 was started. The first measured value for the thickness of the five layers (d.sub.0) was recorded and a further value for the thickness of the five layers (d.sub.20) was recorded 20 s after the first value. The creep tendency C in the thickness direction was determined therefrom according to the following formula.

[00002]$C=100.Math.\frac{d_0-d_{20}}{d_0}$

[0080] The measurement was repeated three times for each of the three filter materials. In addition, the thickness d of a single layer was determined in accordance with ISO 534:2011 from an average of 10 measurements.

[0081] The results are shown in Table 1, wherein d is the thickness of a single layer, do is the thickness of the five layers at the start of the measurement, d.sub.20 is the thickness of the five layers 20 s after the start of the measurement and C is the creep tendency.

TABLE-US-00001 TABLE 1 Filter Material Pressure d [?m] d.sub.0 [?m] d.sub.20 [?m] C [%] A High 273 1345 1317 2.08 A High 1387 1347 2.88 A High 1365 1321 3.22 B Medium 240 1185 1138 3.97 B Medium 1230 1179 4.15 B Medium 1255 1197 4.62 C Low 204 1067 1016 4.78 C Low 1007 953 5.36 C Low 1000 942 5.80

[0082] The values from Table 1 show that the determination of the creep tendency exhibits good repeatability, and thus is a reliable measurement method. It is also noticeable that the creep tendency of the filter material increases with lower pressure of the water jets.

Comparative Example Z

[0083] To manufacture a filter material not according to the invention, the same mixture of fibers was used as with the exemplary embodiments A to C. In step B, however, only one row of water jets and a lower pressure than with comparative example C were chosen, while the basis weight remained unchanged at 25 g/m.sup.2.

[0084] For the filter material Z not according to the invention, the same measurements were carried out as for the filter materials according to the invention A to C and the results are shown in Table 2, wherein the symbols are identical to Table 1.

TABLE-US-00002 TABLE 2 Filter Material d [?m] d.sub.0 [?m] d.sub.20 [?m] C [%] Z 186 947 838 11.51 Z 903 787 12.85 Z 934 796 14.78

[0085] It can be seen that the chosen lower number of water jets and the lower but quite common pressure of the water jets for the filter material not according to the invention lead to a substantially higher creep tendency in the thickness direction than for the exemplary embodiments according to the invention A to C.

[0086] Furthermore, it can be seen that the thickness of the single layer also decreases with the reduction in pressure of the water jets in the order of the exemplary embodiments of A, B, C, and Z. This is an indication that in the exemplary embodiments according to the invention, A to C, a higher proportion of fibers is arranged in the thickness direction than in comparative example Z.

Manufacture of Segments and Smoking Articles

[0087] Filter rods wrapped with paper and with a length of 100 mm and a diameter of 7.85 mm were manufactured from each filter material of the embodiments A to C and from the comparative example Z. The width of the web of filter material and the machine settings during manufacture of the filters were selected here such that a draw resistance of 420?10 mmWG was obtained. Segments with a length of 20 mm were cut from the filter rods and American Blend cigarettes were produced therefrom with a length of 83 mm without filter ventilation. The mean weight of the cigarettes was 925.8 mg.

[0088] The cigarettes were smoked according to a process specified in ISO 3308:2012 and the amount of nicotine-free dry particulate matter per cigarette was determined. The filter segments of the cigarettes were removed and the amount of nicotine-free dry particulate matter in each filter segment was also determined and the filtration efficiency was calculated as a percentage therefrom, wherein the filtration efficiency indicates which proportion of the nicotine-free dry particulate matter flowing into the filter segment is retained. In addition to the properties of the filter material, the filtration efficiency therefore also depends on the length and the diameter of the filter segment.

[0089] The hardness of the filter rods was measured with a DD60A instrument from Borgwaldt KC. In this regard, the filter rods are loaded with a defined force by a test body and the deformation is measured and expressed as a percentage with respect to the undeformed state.

[0090] The draw resistance (PD) of the filter rod, the filtration efficiency (FE) for nicotine-free dry particulate matter and the hardness (HD) of the filter segments are shown in Table 3 for the exemplary embodiments A to C according to the invention and the comparative example Z.

TABLE-US-00003 TABLE 3 PD FE HD Example mmWG % % A 420 56.3 80 B 418 56.9 80 C 425 53.5 78 Z 420 72.0 76

[0091] It can be seen from Table 3 that both the segments according to the invention from the filter materials A to C as well as from the filter material Z not according to the invention have similar draw resistance, filtration efficiency and hardness, so that the segments according to the invention can readily meet the usual requirements for segments for smoking articles.

[0092] In particular, for the hardness of the segments, which is usually measured by a short but high load, no substantial differences can be seen. During experimental smoking of the smoking articles manufactured from the segments, however, a perceptible difference was found as regards how far the filter segments deformed when the consumer held them between the fingers for a longer time. In this subjective evaluation, the filter materials according to the invention and the segments manufactured therefrom exhibit significant advantages.

[0093] Thus, it can be seen that segments can be manufactured from the filter material according to the invention for which the properties with respect to draw resistance, filtration efficiency and hardness correspond to common segments but which have further advantages with respect to the creep tendency and thus come closer overall to segments from cellulose acetate than filter materials from paper, for example. With respect to the biodegradability, the filter materials according to the invention and the segments manufactured therefrom are even more superior to common segments from cellulose acetate.