HYDROENTANGLED FILTER MATERIAL FOR SMOKING ARTICLES HAVING IMPROVED EXPANSION BEHAVIOUR

Abstract

Shown is a hydroentangled nonwoven for manufacturing a segment for a smoking article, wherein the hydroentangled nonwoven is web-shaped and contains at least 50% and at most 100% cellulose fibers, each with respect to the mass of the hydroentangled nonwoven, wherein the hydroentangled nonwoven has a basis weight of at least 15 g/m.sup.2 and at most 60 g/m.sup.2, wherein the hydroentangled nonwoven has a machine direction and a cross direction orthogonal thereto and lying in the plane of the web of the hydroentangled nonwoven, and wherein the hydroentangled nonwoven 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 hydroentangled nonwoven up to half the elongation at break is at least 10% and at most 50% of the total deformation energy absorbed by the hydroentangled nonwoven up to half the elongation at break.

Claims

1. Hydroentangled nonwoven for manufacturing a segment for a smoking article, wherein the hydroentangled nonwoven is web-shaped and contains at least 50% and at most 100% cellulose fibers, each with respect to the mass of the hydroentangled nonwoven, wherein the hydroentangled nonwoven has a basis weight of at least 15 g/m.sup.2 and at most 60 g/m.sup.2, wherein the hydroentangled nonwoven has a machine direction and a cross direction orthogonal thereto and lying in the plane of the web of the hydroentangled nonwoven, and wherein the hydroentangled nonwoven 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 hydroentangled nonwoven up to half the elongation at break is at least 10% and at most 50% of the total deformation energy absorbed by the hydroentangled nonwoven up to half the elongation at break.

2. Hydroentangled nonwoven according to claim 1, in which the proportion of the cellulose fibers in the hydroentangled nonwoven is at least 70% and at most 95%, each with respect to the mass of the hydroentangled nonwoven.

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

4. (canceled)

5. Hydroentangled nonwoven 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 hydroentangled nonwoven.

6. (canceled)

7. Hydroentangled nonwoven 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. Hydroentangled nonwoven according to claim 1, wherein the hydroentangled nonwoven 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 hydroentangled nonwoven up to half the elongation at break is at least 18% and at most 32% of the total deformation energy absorbed by the hydroentangled nonwoven up to half the elongation at break.

9. (canceled)

10. (canceled)

11. Hydroentangled nonwoven 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. Hydroentangled nonwoven according to claim 1, in which at least a portion of the cellulose fibers is loaded with a filler, wherein the filler is formed calcium carbonate particles.

13. Hydroentangled nonwoven according to claim 1, in which the thickness of one layer of the hydroentangled nonwoven, measured in accordance with ISO 534:2011, is at least 35 ?m and at most 600 ?m.

14. (canceled)

15. (canceled)

16. Segment for a smoking article, comprising a hydroentangled nonwoven gathered in the cross direction and a wrapper material, wherein the hydroentangled nonwoven contains at least 50% and at most 100% cellulose fibers, each with respect to the mass of the hydroentangled nonwoven, wherein the hydroentangled nonwoven has a basis weight of at least 15 g/m.sup.2 and at most 60 g/m.sup.2, wherein the hydroentangled nonwoven has a cross direction in which the hydroentangled nonwoven is gathered, and wherein in the non-gathered state, the hydroentangled nonwoven 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 hydroentangled nonwoven up to half the elongation at break is at least 10% and at most 50% of the total deformation energy absorbed by the hydroentangled nonwoven up to half the elongation at break.

17. Segment according to claim 16, in which the hydroentangled nonwoven has one or more of the 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, 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.

22. Process for manufacturing a segment according to claim 16, in which the hydroentangled nonwoven according to claim 1 is crimped or pleated, a continuous tow produced from crimped or pleated hydroentangled nonwoven is formed, the tow of crimped or pleated hydroentangled nonwoven 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, in which the aerosol-forming material is present in liquid form and is located in a corresponding container in the smoking article.

27. Process for manufacturing a hydroentangled nonwoven, 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 proportion of cellulose fibers in the fiber web is selected such that after drying in step A3, the hydroentangled nonwoven contains at least 50% and at most 100% cellulose fibers, with respect to the mass of the hydroentangled nonwoven and wherein steps A1 and A2 are carried out such that the hydroentangled nonwoven is provided with a characteristic plastic deformability in the cross direction, which is characterized in that in a tensile test in the cross direction carried out in accordance with ISO 1924-2:2008 on the hydroentangled nonwoven after drying in step A3, the nonlinear portion of the deformation energy absorbed by the hydroentangled nonwoven up to half the elongation at break is at least 10% and at most 50% of the total deformation energy absorbed by the hydroentangled nonwoven up to half the elongation at break, and wherein after drying in step A3, the hydroentangled nonwoven has a basis weight of at least 15 g/m.sup.2 and at most 60 g/m.sup.2.

28. (canceled)

29. Process according to claim 27, in which the hydroentangling in step A2 is carried out by at least two rows of water jets directed onto the fiber web, wherein at least one row of water jets acts on each of the two sides of the fiber web.

30. (canceled)

31. Process according to claim 27, wherein the hydroentangled nonwoven manufactured according to this process is a hydroentangled nonwoven according to claim 1.

32. Process according to claim 27, in which the step A1 for providing a fiber web comprises the following sub-steps B1 to B3: 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 said fiber web, wherein in step B1, the amount or the proportion of cellulose fibers is selected such that after drying in step A3, the hydroentangled nonwoven contains at least 50% and at most 100% cellulose fibers, with respect to the mass of the hydroentangled nonwoven, wherein said machine direction of the fiber web is defined by the running direction of the wire in step B3 and said cross direction is defined by the direction orthogonal thereto lying in the plane of the fiber web, and wherein in step B2, the suspension is applied to the running wire at a speed which is lower than the speed of the running wire.

33. Process according to claim 32, in which the aqueous suspension in step B1 has a solids content of at most 0.2%.

34. (canceled)

35. (canceled)

36. Process according to claim 27, 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 anhydrides (ASA), polyvinyl alcohol, waxes, fatty acids, starch, starch derivatives, carboxy methyl cellulose, alginates, chitosan, wet strength agents or substances for adjusting the pH, organic or inorganic acids or bases, and mixtures thereof.

37. (canceled)

38. Process according to claim 36, in which the one or more additives is or are applied between the steps A2 and A3, or after step A3, followed by a further step of drying the fiber web.

39. Smoking article according to 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 FIGURES

[0093] FIG. 1 shows, by way of example, a force-elongation-diagram of a hydroentangled nonwoven according to the invention.

[0094] FIG. 2 shows, by way of example, a force-elongation-diagram of a filter material not according to the invention.

[0095] FIG. 3 shows a device by means of which a process according to the invention for manufacturing a hydroentangled nonwoven according to the invention can be carried out.

[0096] FIG. 4 shows force-elongation-curves measured in the cross direction on embodiments A, B and C according to the invention.

[0097] 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

[0098] Some preferred embodiments of the hydroentangled nonwoven, of the process for manufacturing the hydroentangled nonwoven, 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

[0099] The device shown in FIG. 3 was used to manufacture the embodiments A, B and C according to the invention.

[0100] A suspension 31 from pulp fibers and fibers from regenerated cellulose was provided in a storage tank 32, step B1, and from there was pumped to a running wire 33, inclined upwards relative to the horizontal, step B2, and was de-watered by vacuum boxes 39, step B3, so that a fiber web 34 was formed on the wire, the general direction of movement of which is indicated by arrow 310. It should be noted that the steps B1 to B3 are specific sub-steps of the general process step A1 (providing a fiber web comprising cellulose fibers). 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 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 A2. In continuation of step A2, 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 A3, to obtain the hydroentangled nonwoven.

[0101] To manufacture the hydroentangled nonwoven, a mixture of pulp fibers from coniferous woods and Lyocell? fibers was used, wherein the amount of fibers was selected such that the finished hydroentangled nonwoven consisted of 65% pulp fibers and 35% Lyocell? fibers. The finished hydroentangled nonwoven had a basis weight, in accordance with ISO 536:2019, of 55 g/m.sup.2.

[0102] In step A2 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 about 2 MPa and about 40 MPa in three steps (low, medium, high), in order to obtain different hydroentangled nonwovens 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.

[0103] Samples were taken from these hydroentangled nonwovens in the cross direction 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 hydroentangled nonwovens 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 hydroentangled nonwoven C.

[0104] At the half elongation at break 8b/2, the corresponding force F(?.sub.b/2) is determined and the linear portion of the deformation energy E.sub.lin can be calculated therefrom by

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

[0105] 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 without problems by methods of numerical integration. 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.

[0106] The determination of the deformation energies up to half the elongation at break was carried out for all three hydroentangled nonwovens 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 obtain the usual unit of J/m.sup.2, the sample geometry still 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

[0107] 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.

Comparative Example D

[0108] Comparative example D related to the manufacture of a filter material in a process that only comprises the steps B1 to B3 and A3, but not the step for hydroentangling the fiber web. The filter material from Comparative Example D is therefore not according to the invention as it is not a hydroentangled nonwoven. Comparative Example D essentially serves to prove that the execution of steps B1 to B3 (as sub-steps of a preferred embodiment of the step A1) are in fact suitable for contributing to a structure that leads to a desired characteristic plastic deformability in the cross direction, if in step B2, the suspension is applied to the running wire at a reduced speed.

[0109] 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.

[0110] In step B2 of the process, the speed of the outflowing suspension was selected to be 10% lower than the speed of the running wire.

[0111] 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

[0112] The values from Table 2 show that the filter material D produced thereby 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 of the process indeed contribute to the desired plastic deformability in the cross direction, if the suspension in step B2 is applied to the running wire at reduced speed.

Exemplary Embodiment E

[0113] On the other hand, the special execution of step A1 (with reduced speed of application of the suspension in step B2) used in 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 embodiment E described below.

[0114] To manufacture the hydroentangled nonwoven in exemplary 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 hydroentangled nonwoven consisted of 80% pulp fibers and 20% Lyocell? fibers. Step A1 was carried out without firstly providing the pulp fibers in the fiber web with a preferred direction transverse to the machine direction by execution of step B2. The finished hydroentangled nonwoven had a basis weight, in accordance with ISO 536:2019, of 15 g/m.sup.2.

[0115] Step A2 for hydroentangling was carried out as in step A2 of exemplary embodiment B.

[0116] Two samples in the cross direction were taken from the hydroentangled nonwoven 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

[0117] The values from Table 3 show that the hydroentangled nonwoven E manufactured thereby has a proportion of the nonlinear deformation energy of about 17%. A comparison with exemplary embodiments A to C, which were manufactured by means of a combination of suitable execution of the hydroentangling in step A2 and pre-structuring the fiber web by reduced application speed in step B2 shows that this combination allows for higher portions of the nonlinear deformation energy of about 22% to about 28% and can therefore lead to a better performance during crimping. The outlay for the combined process is, of course, slightly higher than if, as in exemplary embodiment E, the characteristic plastic deformability in the cross direction according to the invention is only obtained by suitable execution of the hydroentangling in step A2. The exemplary embodiment E demonstrates that this is indeed possible.

Comparative Example Z

[0118] 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.

[0119] 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

[0120] 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

[0121] Filter rods wrapped with paper with a length of 100 mm and a diameter of 7.85 mm were manufactured from each hydroentangled nonwoven of exemplary embodiments A to E and the filter material of comparative example Z. The width of the hydroentangled nonwoven and the machine settings during filter manufacturing were selected such that a draw resistance of 450?10 mmWG resulted.

[0122] Filter rods could be manufactured from the hydroentangled nonwovens of exemplary embodiments A to C and E and the filter material of comparative example Z. However, during manufacture, it was found that for the hydroentangled nonwovens of exemplary embodiments A to C and 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.

[0123] Filter cigarettes were manufactured from the segments of the exemplary embodiments A to C and E and the comparative example Z according to a common process from the prior art. This manufacturing process was without any problems.

[0124] Thus, it can be seen that segments and smoking articles can be manufactured from the hydroentangled nonwoven 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.