EP4132303B1 - Hydroentangled filter material for smoking articles having improved expansion behaviour - Google Patents

Description

FIELD OF THE INVENTION

The invention relates to a filter material suitable for producing a segment in a smoking article, which has favorable plastic expansion behavior in the transverse direction, so that segments for smoking articles can be produced therefrom in an efficient manner. The invention also relates to a segment for a smoking article made from this filter material.

BACKGROUND AND STATE OF THE ART

Smoking articles are typically rod-shaped articles that consist of at least two rod-shaped segments arranged one after the other. One segment contains a material that is capable of forming an aerosol when heated and at least one further segment serves to influence the properties of the aerosol.

The smoking article can be a filter cigarette, in which a first segment contains the aerosol-forming material, in particular tobacco, and in which a further segment is designed as a filter and serves to filter the aerosol. The aerosol is generated by burning the aerosol-forming material, and the filter primarily serves to filter the aerosol and to provide the filter cigarette with a defined draw resistance.

The smoking article can also be a so-called tobacco heater, in which the aerosol-forming material is only heated but not burned. This reduces the number and amount of harmful substances in the aerosol. Such a smoking article also consists of at least two, but more often of more, in particular four, segments. A segment contains the aerosol-forming material, which typically includes tobacco, reconstituted tobacco, or tobacco prepared by other processes. Further, partly optional segments in the smoking article serve to forward the aerosol, cool the aerosol or filter the aerosol.

The segments are usually covered by a covering material. Paper is very often used as a wrapping material.

In the following, unless it is explicitly stated or something else arises directly from the context, “segment” is understood to mean the segment of a smoking article that does not contain the aerosol-forming material, but rather serves, for example, to forward, cool or filter the aerosol.

It is known from the prior art to form such segments from polymers such as cellulose acetate or polylactides. After consuming the smoking article, the smoking article must be disposed of appropriately. In many cases, however, the consumer simply throws the smoked product away in the environment and attempts to restrict this behavior through information or punishment have had little success.

Since cellulose acetate and polylactides biodegrade very slowly in the environment, the industry has an interest in manufacturing the segments of the smoking article from other materials that are more biodegradable. In addition, in the European Union, for example, regulations are being discussed that significantly reduce or prohibit the use of non-natural polymers in smoking articles, so that for this reason there is also an interest in having alternative segments for smoking articles.

It is known in the art to produce segments for smoking articles, in particular filter segments, from paper. Although such segments are generally readily biodegradable, they also have disadvantages. For example, paper filter segments generally have a high filtration efficiency and therefore result in a dry aerosol, which affects the taste of the aerosol compared to cigarettes with the usual cellulose acetate filter segments. Furthermore, they often have a lower filtration efficiency for phenols than cellulose acetate.

A key reason why paper filter segments have not yet found widespread use is also their visual appearance. At the mouth end of the smoking article, the cut surface of the segment located at the mouth end is often visible, and the consumer is used to a white, homogeneous surface from the usual segments made of cellulose acetate, in which the individual cut fibers are hardly visible. Paper segments, on the other hand, have a coarse structure, which apparently gives the consumer the impression of lower quality. Therefore, paper segments are often only used as a sub-segment in a multi-segment filter, so that the consumer cannot see the cut surface. The segment located at the end of the mouth then often continues to consist of Cellulose acetate. Because of these optical defects, the biodegradability advantages of a paper segment cannot be fully exploited.

It is also known in the art to produce segments for smoking articles from nonwovens. In EP 2 515 689 For example, a filter material made of nonwoven fabric is described, which, however, predominantly contains fibers made of polyvinyl alcohol, polylactides or other non-natural polymers and therefore cannot well meet biodegradability requirements. In addition, the nonwovens described there are too thin to produce a visually appealing appearance on the cut surface of the segment made from them.

It is also known in the prior art to produce filter material for smoking articles made of paper from readily biodegradable fibers. In US 2015/0374030 Such a filter material is described, which, however, consists to a significant extent of cellulose fibers made from hemp, flax, abaca, sisal or cotton. These fibers are expensive and, due to their short growth period compared to wood pulp fibers, have large fluctuations in quality. According to the teaching in US 2015/0374030 However, they are necessary in order to achieve a sufficiently porous structure and sufficiently high strength at the same time. The use of wood pulp is discouraged because it creates a dense and compact paper structure. In fact, the proportion of wood pulp should always be less than 50% by weight and in the industrially implemented exemplary embodiments it is less than 5% by weight. Due to the manufacturing process used, the visual appearance of such filters is not sufficiently appealing to consumers.

Contrary to the teachings from the prior art, the inventors of the present application have found that a filter material with a high proportion of wood pulp fibers can be produced in the form of a hydroentangled nonwoven without the structure of the nonwoven becoming too dense or too compact. A corresponding filter material, which can be seen as a starting point for the present invention, is in the unpublished international application PCT/ EP2019/085125 described. This unpublished application also describes folding or crimping the filter material in order to form an endless strand of folded or crimped filter material, which is subsequently covered with wrapping paper and cut into individual rods of a defined length in order to form the segments mentioned.

For example, when producing a segment, it is possible to first crimp a web of cellulose-based nonwoven in the longitudinal direction before forming it into an endless strand is shaped and covered with a wrapping material. Finally, the endless strand can be cut into pieces suitable for further processing.

When crimping the web, the web can be passed through two patterned rollers that imprint this pattern onto the web. For example, this pattern may be a line pattern oriented in the machine direction of the web. Such embossed lines stretch and deform the web in the direction orthogonal to the machine direction, the transverse direction, so that an endless strand can then be more easily formed by pushing the web together in the transverse direction.

However, with the type of crimping described, it can happen that the sheet tears in the transverse direction. There is therefore a need for a filter material that does not have this disadvantage or only to a lesser extent, but otherwise the preferred filter materials, in particular those described in the above-mentioned unpublished application PCT/EP2019/085125 are described as identical as possible.

EP3385425A1 describes a nonwoven fabric made of cellulose fibers that is produced directly from a Lyocell spinning solution. The fabric comprises a network of substantially continuous fibers, the fabric having an oil absorption capacity of at least 1900% by mass. Furthermore, a method and an apparatus for producing such a substance, a product or a composite containing such a substance and various possible uses for such a substance are described.

DE 12 95 453 B discloses a tobacco product filter made of a covered fiber strand produced by gathering a fiber fleece, the fiber fleece having, in a manner known per se, a proportion of fibers distorted transversely to the direction of travel, but this proportion of transversely distorted fibers has such a size that the not yet covered fiber strand per unit length has a volume that is at least 2:1 larger than a fiber strand produced in the same way from a fiber fleece of the same weight without cross-distorted fibers.

EP2228209A1 discloses an elastic laminate, in particular for elastic diaper fastening elements, with outer layers made of nonwoven and an elastic film laminated at least in regions between the outer layers. At least one of the two outer layers consists of a nonwoven material that is stretchable in the transverse direction and solidified by water jets. The hydroentangled nonwoven fabric is pre-stretched in at least one axial direction in the area of the elastic film.

SUMMARY OF THE INVENTION

The invention is based on the object of providing a web-shaped filter material for a smoking article that can be processed into a segment of a smoking article with high productivity and is otherwise as similar as possible to preferred filter materials in terms of its properties.

This object is achieved by a hydroentangled nonwoven according to claim 1, a segment for a smoking article according to claim 6, and a smoking article according to claim 10, as well as by a method for producing a segment according to claim 9 and a method for producing the hydroentangled nonwoven according to the invention according to claim 11. Advantageous further developments are specified in the dependent claims.

The inventors have found that this problem can be solved by a filter material for producing a segment for a smoking article, the filter material being a web-shaped hydroentangled fleece. Although the term "hydroentangled" initially indicates the underlying manufacturing process, it should be taken into account that a hydroentangled nonwoven has characteristic structural properties that distinguish it from other nonwovens and which, to the knowledge of the inventors, cannot be achieved in an identical manner by another manufacturing process . Unlike, for example, paper, in which the strength is primarily caused by hydrogen bonds and the fibers are arranged primarily in the plane of the paper, the strength of the hydroentangled fleece is achieved by the entanglement of the fibers. A hydroentangled fleece has a particularly porous structure, which makes it particularly suitable as a filter material for segments of smoking articles.

According to the invention, the hydroentangled nonwoven contains at least 50% and at most 100% cellulose fibers, in each case based on the mass of the hydroentangled nonwoven, the hydroentangled nonwoven having a basis weight of at least 15 g/m ² and at most 60 g/m ² . The hydroentangled nonwoven has a machine direction and a transverse direction lying orthogonally thereto in the plane of the web of the hydroentangled nonwoven. Furthermore, the hydroentangled nonwoven has a characteristic plastic deformability in the transverse direction, which is characterized by the fact that in a tensile test in the transverse direction according to ISO 1924-2:2008, the non-linear 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 fleece up to half the elongation at break. This characteristic plastic deformability is more pronounced than is the case with conventional filter materials.

During the production and further processing of the hydroentangled nonwoven, the hydroentangled nonwoven runs through the machine in one direction, the so-called machine direction, and the hydroentangled nonwoven has a direction orthogonal to the machine direction and lying in the web plane of the hydroentangled nonwoven, the transverse direction.

When processing a filter material into a segment of a smoking article, the hydroentangled fleece is preferably crimped. For this purpose, the hydroentangled fleece is passed through, for example, two rollers provided with a pattern, which emboss this pattern onto the web. Preferably, this pattern is a line pattern oriented in the machine direction of the web. The embossed lines stretch and deform the hydroentangled nonwoven in the direction orthogonal to the machine direction, the transverse direction. A filter material deformed in this way can be pushed together more easily in the transverse direction, thus creating an endless strand for producing the segments.

A problem with this method, however, is that the two rollers have to exert a high stretch in the transverse direction on the web in order to achieve the desired deformation of the hydroentangled nonwoven, and there is therefore a risk that the hydroentangled nonwoven will tear in the transverse direction . The person skilled in the art might now be tempted to increase the elongation at break of the hydroentangled nonwoven in the transverse direction so that the hydroentangled nonwoven tolerates larger deformations without tearing. However, the inventors have recognized that this does not solve the problem, because in order to achieve permanent deformation in the transverse direction, the elongation must then be increased even further, so that the risk of exceeding the breaking load in the transverse direction increases even further.

According to the inventors' findings, it is more important that the stretching in the transverse direction to which the hydroentangled fleece is exposed during crimping causes a permanent, plastic and not an elastic deformation. If such a plastic deformation can be achieved with a greater distance between the rollers during crimping, the risk of the hydroentangled fleece tearing in the transverse direction during processing is reduced. In general, it should be sufficient to stretch the hydroentangled fleece in the transverse direction to about half of its elongation at break.

The inventors have now found that the hydroentangled fleece can be equipped with a structure using suitable processes that allows good plastic deformability in the transverse direction and thus simplifies crimping. Suitable methods for this are explained below.

wobei in der Praxis das Integral numerisch berechnet wird.This plastic deformability in the transverse direction can be characterized by a tensile test in accordance with ISO 1924-2:2008. In this tensile test, a strip with a width of 15 mm is taken from the sample in the transverse direction and stretched at a speed of 20 mm/min until it breaks. The strain ε and the applied force F are recorded, resulting in a force-strain curve F(ε). The elongation at break ε _b and the tensile strength F(ε _b ) are also recorded. The deformation energy E absorbed by the hydroentangled fleece up to half the elongation at break ε _b /2 is then given by $$E={\displaystyle {\int }_{\epsilon =0}^{{\epsilon }_b/2}F\left(\epsilon \right)\mathit{d\epsilon },}$$

where in practice the integral is calculated numerically.

This deformation energy consists of an elastic and a plastic portion. The elastic deformation decreases after relief, so it does not contribute to the crimping result. The plastic deformation, on the other hand, is irreversible, so that a good crimping result can be expected even with slight stretching by the two rollers if the proportion of the plastic deformation energy to the total deformation energy is higher than with comparable filter materials from the prior art.

berechnet werden.Elastic deformation is generally associated with a proportionality between strain and force. Under the fictitious assumption that the hydroentangled fleece behaves in an ideally linear elastic manner up to half the elongation at break, the deformation energy E _lin can reach up to half the elongation at break $$E_{\mathit{lin}}=\frac{1}{2}F\left(\frac{{\epsilon }_{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">b</figure-callout>}}}{2}\right)\frac{{\epsilon }_b}{2}=\frac{1}{4}F\left(\frac{{\epsilon }_{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">b</figure-callout>}}}{2}\right){\epsilon }_b$$

be calculated.

Nach den Erkenntnissen der Erfinder lassen sich sehr gute Ergebnisse beim Crimpen erzielen, wenn der bis zur halben Bruchdehnung in Querrichtung aufgenommene nichtlineare Anteil der Verformungsenergie mindestens 10% der gesamten bis zur halben Bruchdehnung in Querrichtung aufgenommenen Verformungsenergie beträgt, also $$\frac{E_{\mathit{nl}}}{E}\ge \mathrm{0,1}$$

gilt.The non-linear portion E _nl of the deformation energy introduced into the hydroentangled fleece up to half the elongation at break is then $$E_{\mathit{nl}}={\displaystyle {\int }_{\epsilon =0}^{{\epsilon }_b/2}F\left(\epsilon \right)\mathit{d\epsilon }-E_{\mathit{lin}}={\displaystyle {\int }_{\epsilon =0}^{\frac{{\epsilon }_b}{2}}F\left(\epsilon \right)\mathit{d\epsilon }-\frac{1}{4}F\left(\frac{{\epsilon }_{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">b</figure-callout>}}}{2}\right){\epsilon }_b.}}$$

According to the inventors' findings, very good results can be achieved in crimping if the nonlinear portion of the deformation energy absorbed up to half the elongation at break in the transverse direction is at least 10% of the total deformation energy absorbed up to half the elongation at break in the transverse direction, i.e $$\frac{E_{\mathit{nl}}}{E}\ge 0.1$$

applies.

These considerations for quantifying plastic behavior can be illustrated by the in Fig. 1 The diagram shown can be illustrated, for example, when carrying out a tensile test in accordance with ISO 1924-2:2008. The elongation ε is plotted on the x-axis 10, while the force F(ε) required to generate this elongation is plotted on the y-axis 11. Starting from an unloaded state 12, the strain ε is increased at a rate of 20 mm/min and at the same time the force F(ε) is measured, whereby the force-strain curve 13 is created. The elongation is increased until the sample tears in state 14, and from this the elongation at break ε _b and the tensile strength F(ε _b ) are determined.

When producing a segment from the hydroentangled fleece, the hydroentangled fleece can be loaded in places, for example, up to approximately half the elongation at break ε _b /2, point 15, with the associated force F (ε _b /2), so that state 16 is reached.

Line 17 connecting points 12 and 16 would represent fictitious linear elastic behavior and the linear deformation energy E _lin corresponds to the area of the triangle formed by points 12, 16 and 15. The total deformation energy E, on the other hand, corresponds to the area enclosed by the lines from point 12 to point 15, from point 15 to point 16 and line 13 from point 16 to point 12. The nonlinear component E _nl of the deformation energy, which is used in the context of the invention to characterize the hydroentangled nonwoven according to the invention, corresponds to the area that is delimited by lines 17 and 13, each between points 12 and 16. The more the force-strain curve bends upwards and the more it deviates from a fictitious linear elastic behavior, the greater the potential for plastic and therefore irreversible deformation.

When producing segments from the hydroentangled fleece according to the invention, the elongation in the transverse direction during crimping can of course deviate from half the elongation at break, and the non-linear portion of the deformation energy can deviate up to half the elongation at break However, regardless of the actual stretch applied and the actual elastic-plastic behavior, it has proven to be a suitable parameter to characterize the structure of the hydroentangled nonwoven according to the invention and to predict the behavior of the hydroentangled nonwoven during crimping.

Shows for comparison Fig. 2 the behavior of a typical conventional filter material not according to the invention. Here too, a tensile test according to ISO 1924-2:2008 is carried out on a sample in the transverse direction. The elongation ε is plotted on the x-axis 20, while the force F(ε) required to generate this elongation is plotted on the y-axis 21. Starting from an unloaded state 22, the strain ε is increased at a rate of 20 mm/min and at the same time the force F(ε) is measured, whereby the force-strain curve 23 is created. The elongation is increased until the sample tears in state 24 and from this the elongation at break ε _b and the tensile strength F(ε _b ) are determined.

When producing a segment from the hydroentangled fleece, the hydroentangled fleece can, for example, be loaded with the associated force F (ε _b /2) up to approximately half the elongation at break ε _b /2, point 25, so that state 26 is reached.

The line 27 connecting points 22 and 26 would represent linear elastic behavior and the associated deformation energy E _lin corresponds to the area of the triangle formed by points 22, 26 and 25. The total deformation energy E, on the other hand, corresponds to the area enclosed by the lines from point 22 to point 25, from point 25 to point 26 and line 23 from point 26 to point 22. The nonlinear component E _nl of the deformation energy corresponds to the area that is delimited by lines 27 and 23, each between points 22 and 26. It can be seen that with very similar elongation at break and a very similar linear proportion of the deformation energy, the proportion of non-linear deformation energy is significantly lower. Such a hydroentangled fleece will therefore react to the deformation primarily elastically and, after relief, will essentially recover the entire deformation. In order to achieve a similar plastic deformation energy as in Fig. 1 To introduce the hydroentangled fleece shown, indicated by line 28, the hydroentangled fleece would have to be stretched to point 29. The elongation required for this is significantly higher and, above all, the force required is close to the breaking load in the transverse direction. In the event of small malfunctions in the machine or fluctuations in the quality of the hydroentangled fleece, the hydroentangled fleece can tear in the transverse direction. The hydroentangled fleece according to the invention Fig. 1 On the other hand, it has a structure that allows permanent deformation in the transverse direction even with a slight stretch, which is why segments for smoking articles can be manufactured more reliably.

The hydroentangled fleece according to the invention contains cellulose fibers. According to the inventors' findings, the cellulose fibers are necessary to provide the hydroentangled nonwoven with sufficient strength so that it can be processed into a segment. According to the invention, the proportion of cellulose fibers in the hydroentangled fleece is at least 50% and at most 100% of the mass of the hydroentangled fleece, but preferably at least 60% and at most 100% and particularly preferably at least 70% and at most 95%, in each case based on the mass of the hydroentangled fleece .

The cellulose fibers can be cellulose fibers or fibers of regenerated cellulose or mixtures thereof.

The pulp fibers are preferably obtained from softwoods, hardwoods or other plants such as hemp, flax, jute, ramie, kenaf, kapok, coconut, abaca, sisal, bamboo, cotton or esparto grass. Mixtures of cellulose fibers from different origins can also be used to produce the hydroentangled fleece. The pulp fibers are particularly preferably obtained from softwoods because even a small proportion of such fibers give the hydroentangled fleece good strength.

The hydroentangled nonwoven according to the invention can contain fibers made from regenerated cellulose. The proportion of fibers made of regenerated cellulose is preferably at least 5% and at most 50%, particularly preferably at least 10% and at most 45% and very particularly preferably at least 15% and at most 40%, in each case based on the mass of the hydroentangled nonwoven.

The fibers made of regenerated cellulose are preferably at least partially, in particular more than 70%, formed by viscose fibers, modal fibers, ^Lyocell® fibers, ^Tencel® fibers or mixtures thereof. These fibers have good biodegradability and can be used to optimize the strength of the hydroentangled nonwoven and to adjust the filtration efficiency of the segment made from it for the smoking article. Due to their manufacturing process, they are less variable than cellulose fibers obtained from natural sources and help ensure that the properties of a segment made from the hydroentangled nonwoven vary less than if only cellulose fibers are used. However, their production is more complex and they are usually more expensive than cellulose fibers.

According to the invention, the basis weight of the hydroentangled nonwoven is at least 15 g/m ² and at most 60 g/m ² , preferably at least 18 g/m ² and at most 55 g/m ² and particularly preferably at least 20 g/m ² and at most 50 g/m ² . The basis weight influences the tensile strength of the hydroentangled nonwoven, with a higher basis weight generally leading to higher strength. However, the basis weight should not be too high because then the hydroentangled fleece can no longer be processed at high speed into segments for smoking articles. The information refers to a basis weight measured according to ISO 536:2019.

In the hydroentangled fleece according to the invention, in a tensile test in the transverse direction according to ISO 1924-2:2008, the nonlinear portion of the deformation energy absorbed by the hydroentangled fleece up to half the elongation at break is at least 10% and at most 50% of the total deformation energy absorbed by the hydroentangled fleece up to half the elongation at break. The non-linear proportion of the deformation energy absorbed by the hydroentangled fleece up to half the elongation at break is preferably at least 15% and at most 40% of the total deformation energy absorbed by the hydroentangled fleece up to half the elongation at break and particularly preferably the non-linear proportion is at least 15% and at most 35%, and in particular at least 18% and at most 32%. In the preferred and particularly preferred intervals, a very good crimping result can be achieved with moderate stretching and the risk of the hydroentangled fleece tearing in the transverse direction is particularly low.

The hydroentangled nonwoven according to the invention can contain additives such as alkyl ketene dimers (AKD), acid anhydrides such as alkenyl succinic anhydride (ASA), polyvinyl alcohol, waxes, fatty acids, starch, starch derivatives, carboxymethyl cellulose, alginates, chitosan, wet strength agents or substances for adjusting the pH, such as organic ones or contain inorganic acids or alkalis to adjust specific properties. The hydroentangled nonwoven according to the invention can alternatively or additionally also contain one or more additives which are selected from the group consisting of citrates, such as trisodium citrate or tripotassium citrate, malates, tartrates, acetates, such as sodium acetate or potassium acetate, nitrates, succinates, fumarates, gluconates, glycolates , lactates, oxyalates, salicylates, α-hydroxycaprylates, phosphates, polyphosphates, chlorides and bicarbonates, and mixtures thereof.

The expert is able to determine the type and amount of such additives based on his or her experience.

The hydroentangled nonwoven according to the invention can also comprise other substances which better adapt the filtration efficiency of the hydroentangled nonwoven to that of cellulose acetate. In a preferred embodiment, the hydroentangled nonwoven according to the invention comprises a substance selected from the group consisting of triacetin, propylene glycol, sorbitol, glycerol, polyethylene glycol, polypropylene glycol, polyvinyl alcohol and tri-ethyl citrate or mixtures thereof.

In a preferred embodiment of the hydroentangled nonwoven, at least some of the cellulose fibers are loaded with a filler, the filler particularly preferably being formed by mineral particles and in particular calcium carbonate particles. Since the structure of the hydroentangled nonwoven is very porous, it is not suitable for holding fillers, so it is advantageous to load the cellulose fibers with the fillers and thus fix them in the structure of the hydroentangled nonwoven. Fillers can be used to give the hydroentangled fleece special properties.

The thickness of a layer of the hydroentangled nonwoven, measured according to ISO 534:2011, is preferably at least 25 µm and at most 1000 µm, preferably at least 30 µm and at most 800 µm and particularly preferably at least 35 µm and at most 600 µm. The thickness influences the amount of hydroentangled web that can be packed into the segment of the smoking article and thus the draw resistance and filtration efficiency of the segment, but also the processability of the hydroentangled web, particularly when it is crimped or folded to produce a segment for a smoking article. For such process steps, a thickness that is too high is unfavorable and thicknesses in the preferred and particularly preferred intervals allow the hydroentangled fleece according to the invention to be processed particularly well into a segment of a smoking article.

The mechanical properties of the hydroentangled nonwoven are important for the processing of the hydroentangled nonwoven according to the invention into a segment of a smoking article. The width-related tensile strength of the hydroentangled nonwoven in the transverse direction, measured according to ISO 1924-2:2008, is preferably at least 0.05 kN/m and at most 5 kN/m, particularly preferably at least 0.07 kN/m and at most 4 kN/m.

The elongation at break of the hydroentangled nonwoven in the transverse direction, measured according to ISO 1924-2:2008, is therefore preferably at least 0.5% and at most 50% and particularly preferably at least 0.8% and at most 40%. The elongation at break is primarily determined by the length of the fibers, with longer fibers leading to higher elongation at break can thus be adapted over a wide range to the specific requirements of the hydroentangled nonwoven.

Segments for smoking articles according to the invention can be produced from the hydroentangled fleece according to the invention using methods known per se from the prior art. These methods include, for example, crimping the hydroentangled web, forming an endless strand from the crimped hydroentangled web, covering the endless strand with a wrapping material, and cutting the covered strand into individual rods of defined length. In many cases, the length of such a rod is an integer multiple of the length of the segment that is then to be used in the smoking article according to the invention, and therefore the rods are cut into segments of the desired length before or during manufacture of the smoking article.

The segment for smoking articles according to the invention comprises the hydroentangled fleece according to the invention and a wrapping material.

Specifically, the segment comprises a hydroentangled fleece pushed together in the transverse direction and a wrapping material, the hydroentangled fleece containing at least 50% and at most 100% cellulose fibers, in each case based on the mass of the hydroentangled fleece. The hydroentangled fleece has a basis weight of at least 15 g/m ² and at most 60 g/m ² . To determine the basis weight, the area of the hydroentangled fleece is taken as a basis when it is spread out (i.e. no longer pushed together). The hydroentangled nonwoven has a transverse direction in which the hydroentangled nonwoven is pushed together. To make it easier to push the hydroentangled fleece together, it can be pre-shaped by crimping or folding. The term "pushing together" is to be understood broadly, and the verb "pushing" contained therein is not intended to suggest a specific mechanical way in which the "pushed together" state is achieved. A “gathered” state, for example, is also a “collapsed” state in the sense of the present disclosure, regardless of the mechanical way in which the gathering or shortening is produced in the transverse direction. Furthermore, the hydroentangled nonwoven has a characteristic plastic deformability in the transverse direction in the non-collapsed state, which is characterized by the fact that in a tensile test in the transverse direction according to 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 a maximum of 50% of the to The total deformation energy absorbed by the hydroentangled fleece is equal to half the elongation at break.

In a preferred embodiment of the segment according to the invention, the segment is cylindrical with a diameter of at least 3 mm and at most 10 mm, particularly preferably at least 4 mm and at most 9 mm and most preferably at least 5 mm and at most 8 mm. These diameters are favorable for using the segments according to the invention in smoking articles.

In a preferred embodiment of the segment according to the invention, the segment has a length of at least 4 mm and at most 40 mm, particularly preferably at least 6 mm and at most 35 mm and most preferably at least 10 mm and at most 28 mm.

The pulling resistance of the segment determines, among other things, what pressure difference the consumer has to apply when using the smoking article in order to generate a certain volume flow through the smoking article, and therefore has a significant influence on the consumer's acceptance of the smoking article. The tensile resistance of the segment can be measured according to ISO 6565:2015 and is given in mm water column (mmWG). To a very good approximation, the tensile resistance of the segment is proportional to the length of the segment, so that the tensile resistance can also be measured on rods that only differ from the segment in length. From this, the tensile resistance of the segment can be easily calculated.

The tensile resistance of the segment per length of the segment is preferably at least 1 mmWG/mm and at most 12 mmWG/mm and particularly preferably at least 2 mmWG/mm and at most 10 mmWG/mm.

The wrapping material of the segment according to the invention is preferably a paper or a film.

The wrapping material of the segment according to the invention preferably has a basis weight according to ISO 536:2019 of at least 20 g/m ² and at most 150 g/m ² , particularly preferably at least 30 g/m ² and at most 130 g/m ² . A wrapping material with this preferred or particularly preferred basis weight gives the segment according to the invention covered with it a particularly advantageous hardness.

Smoking articles according to the invention can be produced from the segment according to the invention using methods known in the prior art.

The smoking article of the invention includes a segment containing an aerosol-forming material and a segment comprising the hydroentangled nonwoven fabric of the invention and a wrapping material.

Since the cut surface of the segment according to the invention is visually very similar to that of a segment made of cellulose acetate, in a preferred embodiment, the segment of the smoking article closest to the mouth end is a segment according to the invention.

In a preferred embodiment, the smoking article is a filter cigarette and the aerosol-forming material comprises tobacco.

In a preferred embodiment, the smoking article is a smoking article, in the intended use of which the aerosol-forming material is only heated but not burned, and the aerosol-forming material preferably comprises a material selected from the group consisting of tobacco, reconstituted tobacco, nicotine, glycerol, propylene glycol or mixtures from it. The aerosol-forming material can also be in liquid form and located in a suitable container in the smoking article.

According to the inventors' findings, the nonlinear portion of the deformation energy according to the invention can be achieved by aligning the fibers in the hydroentangled nonwoven more strongly in the machine direction of the hydroentangled nonwoven. This can be achieved by the methods according to the invention described below.

• A1 - Bereitstellen einer Faserbahn umfassend Cellulosefasern, die eine Maschinenrichtung und eine dazu orthogonale in der Bahnebene liegende Querrichtung aufweist,
• A2 - Wasserstrahlverfestigen der Faserbahn durch auf die Faserbahn gerichtete Wasserstrahlen, um eine wasserstrahlverfestigte Faserbahn herzustellen,
• A3 - Trocknen der wasserstrahlverfestigten Faserbahn,

wobei in Schritt A1 der Anteil der Cellulosefasern in der Faserbahn so gewählt ist, dass das wasserstrahlverfestigte Vlies nach dem Trocknen in Schritt A3 mindestens 50% und höchstens 100% Cellulosefasern, bezogen auf die Masse des wasserstrahlverfestigten Vlieses, enthält, und wobei die Schritte A1 und A2 so durchgeführt werden, dass dem wasserstrahlverfestigten Vlies eine charakteristische plastische Verformbarkeit in Querrichtung verliehen wird, die dadurch charakterisiert ist, dass in einem am wasserstrahlverfestigten Vlies nach dem Trocknen in Schritt A3 durchgeführten Zugversuch in Querrichtung gemäß ISO 1924-2:2008 der nichtlineare Anteil der bis zur halben Bruchdehnung vom wasserstrahlverfestigten Vlies aufgenommenen Verformungsenergie mindestens 10% und höchstens 50% der bis zur halben Bruchdehnung vom wasserstrahlverfestigten Vlies aufgenommenen gesamten Verformungsenergie beträgt, und wobei das wasserstrahlverfestigte Vlies nach dem Trocknen in Schritt A3 ein Flächengewicht von mindestens 15 g/m² und höchstens 60 g/m² aufweist.The hydroentangled nonwoven fabric according to the invention can be produced by a process comprising the following steps A1 to A3.

• A1 - Providing a fiber web comprising cellulose fibers which has a machine direction and a transverse direction lying orthogonally thereto in the plane of the web,
• A2 - hydroentanglement of the fiber web by water jets directed onto the fiber web to produce a hydroentangled fiber web,
• A3 - drying the hydroentangled fiber web,

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

Steps A1 and A2 can be carried out in such a way that the cellulose fibers in the finished hydroentangled nonwoven tend to be oriented more in the machine direction than in the transverse direction.

The water jets directed at the fiber web in step A2 cause the cellulose fibers to be swirled, whereby the structure that is conducive to the favorable plastic behavior in the transverse direction can be created. The person skilled in the art understands the “pressure of the water jet” to mean the pressure that is used to generate the water jet, for example in a pressure chamber. According to the inventors' findings, in order to achieve favorable plastic behavior of the hydroentangled nonwoven, it is important that the proportion of transversely oriented fibers in the hydroentangled nonwoven is small and that the fibers are oriented more in the machine direction and thickness direction. In order to produce this structure according to the invention in the hydroentangled fleece, the water jets should be arranged close to one another in the transverse direction. Due to the proximity of the water jets hitting the fiber web at the same time, the water deviates in the machine direction rather than in the transverse direction and orients the fibers in this direction.

The pressure of the water jets can be reduced compared to the pressure normally used. The distance and pressure of the water jets also depends significantly on the size of the openings from which the water jets emerge and, above all, on the speed of the fiber web, so that the expert can determine the specific value based on experience, based on the specific exemplary embodiments and can choose through simple experiments.

In a preferred embodiment of the method according to the invention, a large number of water jets are used to carry out the hydroentanglement in step A2, wherein the water jets are arranged in at least one row transverse to the machine direction of the fiber web.

In a preferred embodiment of the method according to the invention, the hydroentanglement in step A2 is effected by at least two rows of water jets directed onto the fiber web, with at least one row of water jets particularly preferably acting on each of the two sides of the fiber web.

In a preferred embodiment of the method according to the invention, the drying in step A3 is at least partially brought about by contact with hot air, by infrared radiation or by microwave radiation. Drying by direct contact with a heated surface is also possible, but is less preferred because the thickness of the hydroentangled nonwoven may decrease.

The hydroentangled fleece produced using this process is said to be suitable for use in segments for smoking articles. This means that it can in particular have all of the features, individually or in combination, which were described above in connection with the hydroentangled nonwoven and are defined in the claims directed to the hydroentangled nonwoven.

• B1 - Herstellen einer wässrigen Suspension umfassend Cellulosefasern,
• B2 - Aufbringen der Suspension aus Schritt B1 auf ein umlaufendes Sieb,
• B3 - Entwässern der Suspension durch das umlaufende Sieb, um die genannte Faserbahn zu bilden,
• wobei in Schritt B1 die Menge oder der Anteil der Cellulosefasern so gewählt ist, dass das wasserstrahlverfestigte Vlies nach dem Trocknen in Schritt A3 mindestens 50% und höchstens 100% Cellulosefasern, bezogen auf die Masse des wasserstrahlverfestigten Vlieses, enthält, und wobei in Schritt B3 durch die Laufrichtung des Siebs die genannte Maschinenrichtung der Faserbahn definiert wird und durch die dazu orthogonale in der Ebene der Faserbahn liegende Richtung die genannte Querrichtung definiert wird, und
• wobei in Schritt B2 die Suspension mit einer Geschwindigkeit auf das umlaufende Sieb aufgebracht wird, die geringer ist als die Geschwindigkeit des umlaufenden Siebs. Dabei sind die Geschwindigkeiten des umlaufenden Siebs und der Suspension jeweils in Bezug auf dasselbe Bezugssystem zu verstehen, sodass voneinander abweichende Geschwindigkeiten zu einer Relativgeschwindigkeit zwischen Suspension und umlaufendem Sieb führt, die bei dieser Ausführungsform des Verfahrens ausgenutzt wird.

In an advantageous development, said step A1 of providing the fiber web includes the following sub-steps B1 to B3:

• B1 - producing an aqueous suspension comprising cellulose fibers,
• B2 - applying the suspension from step B1 to a rotating sieve,
• B3 - dewatering the suspension through the rotating sieve to form said fiber web,
• wherein in step B1 the amount or proportion of cellulose fibers is selected such that the hydroentangled nonwoven contains at least 50% and at most 100% cellulose fibers, based on the mass of the hydroentangled nonwoven, after drying in step A3, and wherein in step B3 the running direction of the sieve defines the said machine direction of the fiber web and the said transverse direction is defined by the direction orthogonal thereto in the plane of the fiber web, and
• wherein in step B2 the suspension is applied to the rotating sieve at a speed that is lower than the speed of the rotating sieve. The speeds of the rotating sieve and the suspension are each related to the same Reference system to be understood, so that deviating speeds lead to a relative speed between suspension and rotating sieve, which is exploited in this embodiment of the method.

In this embodiment of the method, the fiber web is given the desired structure at least partially by the speed at which the suspension flows onto the rotating sieve in step B2 and the speed of the rotating sieve in step B2 being suitably coordinated with one another. In particular, according to the inventors' findings, the speed at which the suspension flows onto the rotating sieve in step B2 should be smaller than the speed of the rotating sieve. Due to the difference in speed, the suspension is carried along by the sieve and shear forces arise in the suspension, which align the cellulose fibers in the machine direction and thus contribute to a structure of the hydroentangled nonwoven, which leads to the plastic deformability in the transverse direction according to the invention. The person skilled in the art can determine the size of the speed difference based on their experience and based on the exemplary embodiments or through simple experiments. According to the inventors' experience, a structure with the desired plastic deformability in the transverse direction can be achieved in many cases if, in step B2, the suspension is applied to the rotating sieve at a speed that is only about 90% of the speed of the rotating sieve, for example between 88 % and 93% of the speed of the rotating sieve. However, this information only serves as a guide; a suitable numerical value of the differential speed will depend at least partially on the other process parameters, and the person skilled in the art will therefore determine it experimentally in practice, with the resulting characteristic plastic deformability of the material produced in this way being the guideline and ultimately the decisive criterion hydroentangled nonwoven in the transverse direction, which is characterized as described above with reference to the tensile test in the transverse direction according to ISO 1924-2:2008.

In a preferred development, the aqueous suspension in step B1 has a solids content of at most 3.0%, particularly preferably at most 1.0%, very particularly preferably at most 0.2% and in particular at most 0.05%. The particularly low solids content of the suspension allows a low-density fiber web to be formed in step B3, which has a positive effect on the filtration efficiency of a segment made from it.

In a preferred embodiment, the rotating wire of steps B2 and B3 is inclined upwards in the machine direction of the fiber web relative to the horizontal by an angle of at least 3° and at most 40°, particularly preferably by an angle of at least 5° and at most 30° and most preferably at an angle of at least 15° and at most 25°.

In a preferred embodiment, the method comprises a step in which a pressure difference is generated between the two sides of the rotating sieve in order to support the dewatering of the suspension in step B3, the pressure difference being particularly preferably generated by vacuum boxes or suitably shaped vanes.

In a preferred embodiment, the method comprises a further step in which one or more additives are applied to the fiber web. The additives are preferably selected from the group consisting of alkyl ketene dimers (AKD), acid anhydrides such as alkenyl succinic anhydrides (ASA), polyvinyl alcohol, waxes, fatty acids, starch, starch derivatives, carboxymethyl cellulose, alginates, chitosan, wet strength agents or substances for adjusting the pH, such as for example organic or inorganic acids or alkalis, and mixtures thereof. Alternatively or additionally, one or more additives can also be applied, which are selected from the group consisting of citrates, such as trisodium citrate or tripotassium citrate, malates, tartrates, acetates, such as sodium acetate or potassium acetate, nitrates, succinates, fumarates, gluconates, glycolates, lactates, Oxyalates, salicylates, α-hydroxycaprylates, phosphates, polyphosphates, chlorides and hydrogen carbonates, and mixtures thereof.

In a preferred embodiment, the one or more additives are applied between steps A2 and A3 of the method according to the invention or after step A3, followed by a further step of drying the fiber web.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1

shows an exemplary force-strain diagram of a hydroentangled fleece according to the invention.

Figure 2

shows an exemplary force-strain diagram of a filter material not according to the invention.

Figure 3

shows a device by means of which a method according to the invention for producing a hydroentangled nonwoven according to the invention can be carried out.

Figure 4

shows force-strain curves measured in the transverse direction on the exemplary embodiments A, B and C according to the invention.

Figure 5

shows force-strain curves measured in the transverse direction on the comparative example Z not according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS AND A COMPARATIVE EXAMPLE

Some preferred embodiments of the hydroentangled nonwoven, the methods for producing the hydroentangled nonwoven, the segment for smoking articles and the smoking article are described below. Furthermore, a comparative example not according to the invention is described.

Embodiments A, B and C

To produce the exemplary embodiments A, B and C according to the invention, the in Figure 3 Device shown used.

A suspension 31 of pulp fibers and fibers of regenerated cellulose was provided in a storage container 32, step B1, and from there pumped onto a rotating sieve 33 inclined upwards against the horizontal, step B2, and dewatered through vacuum boxes 39, step B3, so that a fiber web 34 formed on the sieve, the general direction of movement of which is indicated by the arrow 310. Note that steps B1 to B3 are concrete sub-steps of the general process step A1 (providing a fiber web comprising cellulose fibers). The speed at which the sieve 33 moves was chosen to be approximately 10% higher than the speed of the suspension 31 flowing out of the storage container 32 in order to orient the fibers primarily in the machine direction. The fiber web 34 was removed from the sieve 33 and transferred to a support sieve 35 which also runs around. There, water jets 311 arranged in several rows transversely to the machine direction of the fiber web 34 were directed onto the fiber web 34 from devices 36 in order to swirl the fibers and solidify the fiber web 34 into a nonwoven fabric, step A2. Continuing from step A2, additional devices 37 also directed water jets 312 to the other side of the fiber web 34. The still-moist nonwoven then passed through a drying device 38 and was dried there, step A3, in order to obtain the hydroentangled nonwoven.

To produce the hydroentangled nonwoven, a mixture of cellulose fibers from softwoods and Lyocell ^® fibers was used, with the amounts of fibers chosen so that the finished hydroentangled nonwoven consisted of 65% cellulose fibers and 35% Lyocell ^® fibers. The finished hydroentangled fleece had a basis weight of 55 g/m ² according to ISO 536:2019.

In step A2 of the manufacturing process, three rows of water jets, 311 in Fig. 3 , directed at the first side of the fiber web 34 and then a series of water jets, 312 in Fig. 3 , directed to the second side of the fiber web 34. The pressure of the water jets was varied between 2 MPa and 40 MPa in three stages (low, medium, high) in order to obtain different hydroentangled nonwovens A, B and C according to the invention. The diameter of the openings from which the water jets emerged varied in the rows and was chosen between 80 µm and 120 µm; the distance between the openings from center to center was 0.3 mm.

Samples were taken from these hydroentangled nonwovens in the transverse direction and the force-strain diagram was recorded in a tensile test in accordance with ISO 1924-2:2008. The result is in Figure 4 shown. The elongation is plotted in % on the x-axis 40, while the force is plotted in N on the y-axis 41. The three lines labeled A, B and C show the force-strain diagrams of the three hydroentangled nonwovens A, B and C according to the invention. An example is the determination of the non-linear proportion of the deformation energy absorbed up to half the elongation at break of the total absorbed up to half the elongation at break Deformation energy for the hydroentangled fleece C explained.

berechnet werden.At half the elongation at break ε _b /2, the associated force F(ε _b /2) is determined and the linear component of the deformation energy E _lin can be calculated from this $$E_{\mathit{lin}}=\frac{1}{4}F\left(\frac{{\epsilon }_{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">b</figure-callout>}}}{2}\right){\epsilon }_b$$

be calculated.

The total deformation energy E absorbed up to half the elongation at break corresponds to the area spanned by x-axis 40 and curve C from ε = 0 to ε = ε _b /2 and can easily be determined with sufficient accuracy using numerical integration methods. If the linear portion of the deformation energy E _lin is subtracted from this, what remains is the area shown as hatched, which corresponds to the non-linear portion of the deformation energy E _nl .

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 given in Table 1, where E is the total deformation energy, E _lin the linear portion of the deformation energy and E _nl the nonlinear portion of the deformation energy each in the transverse direction means up to half the elongation at break. The deformation energies were determined numerically from the force-strain curve and formally have the unit N%. In order to arrive at the usual unit J/m ² , the sample geometry must also be taken into account. Since what matters here is only the relationships between each other and the sample geometries are identical, this is omitted. The elongation at break ε _b and the force at half elongation at break F(ε _b /2) are also given. Table 1 E.g. Pressure ε _b [%] F(ε _b /2) [N] E _Elin E _nl E _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

The values from Table 1 show that in the exemplary embodiments A, B and C according to the invention there is a non-linear proportion of the deformation energy of approximately 20% to approximately 30%. It can also be seen that as the pressure of the water jets increases, the elongation at break decreases. For this reason, it can be advantageous to choose a low water jet pressure because, in addition to the good plastic expansion behavior, even larger permanent deformations are possible during crimping.

Comparative Example D

Comparative example D relates to the production of a filter material in a process which only contains steps B1 to B3 and A3, but not the step of hydroentanglement of the fiber web. The filter material from comparative example D is not according to the invention in that it is not a hydroentangled fleece. Comparative example D essentially serves to demonstrate that carrying out process steps B1 to B3 (as sub-steps of a preferred embodiment of process step A1) is in fact suitable for contributing to a structure that leads to a desired characteristic plastic deformability in the transverse direction, if in step B2 the suspension is applied to the rotating sieve at a reduced speed.

To produce the filter material, a mixture of cellulose fibers from softwoods and Lyocell ^® fibers was used, with the amounts of fiber chosen so that the finished product Filter material consisted of 80% cellulose fibers and 20% Lyocell ^® fibers. The finished filter material had a basis weight of 15 g/m ² according to ISO 536:2019.

In step B2 of the process, the speed of the outflowing suspension was chosen to be approximately 10% lower than the speed of the rotating sieve.

Four samples were taken in the transverse direction from the filter material D obtained in this way and the force-strain diagram was recorded in a tensile test in accordance with ISO 1924-2:2008. The evaluation of the force-strain diagrams was carried out analogously to exemplary embodiments A to C. The results of the four measurements are shown in Table 2 Table 2 E.g. ε _b [%] F(ε _b /2) [N] E _Elin E _nl E _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

The values from Table 2 show that the filter material D produced in this way has a non-linear proportion of the deformation energy of approximately 30% and that repeat measurements on the same sample material have a small scatter. This proves that process steps B1 to B3 actually contribute to the desired plastic deformability in the transverse direction when the suspension is applied to the rotating screen at reduced speed in step B2.

Embodiment E

On the other hand, the special implementation of step A1 (with reduced application speed of the suspension in step B2) used in exemplary embodiments A to C is not necessary in order to obtain the characteristic plastic deformability according to the invention in the transverse direction in the hydroentangled nonwoven. This can be seen from exemplary embodiment E described below.

To produce the hydroentangled nonwoven, in exemplary embodiment E a mixture of cellulose fibers from softwoods and ^Lyocell® fibers was used, the amounts of fibers being chosen so that the finished hydroentangled nonwoven consisted of 80% cellulose fibers and 20% ^Lyocell® fibers. Step A1 was carried out without the pulp fibers in the fiber web first by carrying out step B2 to give a preferred direction transverse to the machine direction. The finished hydroentangled fleece had a basis weight of 15 g/m ² according to ISO 536:2019.

Step A2 of hydroentanglement takes place like step A2 of exemplary embodiment B.

Two samples were taken in the transverse direction from the hydroentangled nonwoven E obtained in this way and the force-strain diagram was recorded in a tensile test in accordance with ISO 1924-2:2008. The evaluation of the force-strain diagrams was carried out analogously to exemplary embodiments A to C. The results of the two measurements are shown in Table 3. Table 3 E.g. ε _b [%] F(ε _b /2) [N] E _Elin E _nl E _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

The values from Table 3 show that the hydroentangled nonwoven E produced in this way has a proportion of nonlinear deformation energy of approximately 17%. The comparison with exemplary embodiments A to C, which were produced using the combination of suitable hydroentanglement in step A2 and pre-structuring of the fiber web by reduced application speed in step B2, shows that this combination produces higher proportions of the nonlinear deformation energy of about 22% to about 28 % is allowed and can thus lead to better behavior when crimping. The effort of the combined method is of course somewhat higher than if, as in exemplary embodiment E, the characteristic plastic deformability according to the invention in the transverse direction is only obtained by appropriately carrying out the hydroentanglement in step A2. Embodiment E demonstrates that this is indeed possible.

Comparative example Z

To produce a filter material not according to the invention, the same mixture of fibers was used as in exemplary embodiment D. The weight per unit area was still 15 g/m ² , but only machine settings were used as are common in the production of conventional filter papers.

Three samples were taken in the transverse direction from the filter material of comparative example Z and the force-strain diagram was recorded in a tensile test in accordance with ISO 1924-2:2008. The evaluation of the force-strain diagrams was carried out analogously to exemplary embodiments A to C. The results of the three measurements are shown in Table 4. Table 4 E.g. ε _b [%] F(ε _b /2) [N] E _Elin E _nl E _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

The force-strain curves of comparative example Z are in Fig. 5 shown. Even without quantitative analysis, it can already be seen that the behavior is much closer to linear elastic behavior, so that deformations are essentially reduced again when the load is relieved and much larger strains and forces are necessary to achieve permanent deformations. The breaking load or the breaking elongation in the transverse direction can easily be exceeded.

Manufacture of segments and smoking articles

Paper-covered filter rods with a length of 100 mm and a diameter of 7.85 mm were made from each hydroentangled fleece of exemplary embodiments A to C and E and the filter material from comparative example Z. The web width of the hydroentangled fleece or filter material and the machine settings during filter production were chosen so that a tensile resistance of 450 ± 10 mmWG resulted.

Filter rods could be produced from the hydroentangled nonwovens from exemplary embodiments A to C and E and the filter material from comparative example Z. During production, however, it became apparent that in the case of the hydroentangled nonwovens of exemplary embodiments A to C and E, the crimping process was significantly less sensitive to changes in the machine settings and in particular to the setting of the distance between the rollers during crimping than in comparative example Z.

Filter cigarettes were produced from the segments of exemplary embodiments A to C and E and comparative example Z using a conventional method from the prior art. This manufacturing process went smoothly.

It can therefore be seen that segments and smoking articles can be manufactured more reliably and easily from the hydroentangled fleece according to the invention than from conventional, hydroentangled fleeces or papers and that a better result can be achieved when crimping due to the favorable plastic expansion behavior.

Claims (15)

1. A hydroentangled nonwoven for producing a segment for a smoking article, wherein the hydroentangled nonwoven is web-shaped and contains at least 50% and at most 100% cellulose fibers, in each case based on the mass of the hydroentangled nonwoven,

   wherein the hydroentangled nonwoven has a basis weight of at least 15 g/m² and at most 60 g/m², wherein the hydroentangled nonwoven has a machine direction and a transverse direction orthogonal thereto in the plane of the web of the hydroentangled nonwoven,

   and wherein the hydroentangled nonwoven has a characteristic plastic deformability in the transverse direction, which is characterised in that in a tensile test in the transverse direction according to ISO 1924-2:2008, the non-linear proportion 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. The hydroentangled nonwoven according to claim 1, wherein the proportion of cellulose fibers in the hydroentangled nonwoven is at least 60% and at most 100%, preferably at least 70% and at most 95%, in each case based on the mass of the hydroentangled nonwoven.
3. The hydroentangled nonwoven according to claim 1 or 2, wherein the cellulose fibers are formed by pulp fibers, by fibers of regenerated cellulose or mixtures thereof,

   wherein the pulp fibers are preferably obtained from softwood or softwoods, hardwood or hardwoods or other plants, in particular hemp, flax, jute, ramie, kenaf, kapok, coconut, abaca, sisal, bamboo, cotton or from espartogras; or by a mixture of pulp fibers of various of these types of origin, and/or

   wherein the proportion of fibers of regenerated cellulose is preferably at least 5% and at most 50%, preferably at least 10% and at most 45% and particularly preferably at least 15% and at most 40%, in each case based on the mass of the hydroentangled nonwoven, and/or

   wherein the fibers of regenerated cellulose are preferably formed at least partly by viscose fibers, modal fibers, Lyocell^® fibers, Tencel^® fibers or mixtures thereof.
4. The hydroentangled nonwoven according to any one of the preceding claims, the basis weight of which is at least 18 g/m² and at most 55 g/m², preferably at least 20 g/m² and at most 50 g/m², and/or

   wherein the hydroentangled nonwoven has a characteristic plastic deformability in the transverse direction, which is characterised in that in said tensile test in the transverse direction according to ISO 1924-2:2008, the non-linear proportion of the deformation energy absorbed by the hydroentangled nonwoven up to half the elongation at break is at least 15% and at most 40%, preferably at least 15% and at most 35%, and in particular at least 18% and at most 32% of the total deformation energy absorbed by the hydroentangled nonwoven up to half the elongation at break, and/or

   wherein at least a part of the cellulose fibers is loaded with a filler, wherein the filler is preferably formed by mineral particles, in particular calcium carbonate particles.
5. The hydroentangled nonwoven according to any one of the preceding claims, wherein the thickness of a layer of the hydroentangled nonwoven, measured according to ISO 534:2011, is at least 25 µm and at most 1000 µm, preferably at least 30 µm and at most 800 µm and particularly preferably at least 35 µm and at most 600 µm, and/or

   wherein the width-related tensile strength of the hydroentangled nonwoven in the transverse direction, measured according to ISO 1924-2:2008, is at least 0.05 kN/m and at most 5 kN/m, preferably at least 0.07 kN/m and at most 4 kN/m, and/or

   wherein the elongation at break of the hydroentangled nonwoven in the transverse direction, measured according to ISO 1924-2:2008, is at least 0.5% and at most 50%, preferably at least 0.8% and at most 40%.
6. A segment for a smoking article, comprising a hydroentangled nonwoven pushed together in the transverse direction and a wrapping material, wherein the hydroentangled nonwoven contains at least 50% and at most 100% cellulose fibers, in each case based on the mass of the hydroentangled nonwoven,
   wherein the hydroentangled nonwoven has a basis weight of at least 15 g/m² and at most 60 g/m², wherein the hydroentangled nonwoven has a transverse direction in which the hydroentangled nonwoven is pushed together, and wherein the hydroentangled nonwoven in the non-pushed-together state has a characteristic plastic deformability in the transverse direction, which is characterised in that in a tensile test in the transverse direction according to ISO 1924-2:2008, the non-linear proportion 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.
7. The segment according to claim 6, wherein the hydroentangled nonwoven has one or more of the additional features defined in claims 2 to 5, and/or
   wherein the segment is cylindrical with a diameter of at least 3 mm and at most 10 mm, preferably of at least 4 mm and at most 9 mm and particularly preferably of at least 5 mm and at most 8 mm, and/or wherein the segment has a length of at least 4 mm and at most 40 mm, preferably of at least 6 mm and at most 35 mm and particularly preferably of at least 10 mm and at most 28 mm.
8. The segment according to any one of claims 6 or 7, wherein the tensile strength of the segment according to ISO 6565:2015 per length of the segment is at least 1 mmWG/mm and at most 12 mmWG/mm, and preferably at least 2 mmWG/mm and at most 10 mmWG/mm, and/or

   the wrapping material thereof is formed by a paper or a film, and/or

   the wrapping material thereof has a basis weight according to ISO 536:2019 of at least 20 g/m² and at most 150 g/m², preferably of at least 30 g/m² and at most 130 g/m².
9. A method for producing a segment according to any one of claims 6 to 8, wherein a hydroentangled nonwoven according to any one of claims 1 to 5 is crimped or folded, a preferably endless strand of crimped or folded hydroentangled nonwoven is formed, the strand of crimped or folded hydroentangled nonwoven is wrapped with a wrapping material and the wrapped strand is cut into individual rods of defined length.
10. A smoking article, comprising a segment which contains an aerosol-forming material, and a segment according to any one of claims 6 to 8, wherein said segment according to any one of claims 6 to 8 preferably forms the segment of the smoking article located closest to the mouth end,

    wherein the smoking article is in particular a filter cigarette and the aerosol-forming material is or contains tobacco, or

    wherein the smoking article is in particular a smoking article, in the intended use of which the aerosol-forming material is only heated but not burned, wherein the aerosol-forming material preferably comprises a material which is selected from the group consisting of tobacco, reconstituted tobacco, nicotine, glycerol, propylene glycol or mixtures thereof,

    wherein the aerosol-generating material is preferably present in liquid form and is located in an associated container in the smoking article.
11. A method for producing a hydroentangled nonwoven, wherein the method comprises the following steps:

    A1 - providing a fibrous web comprising cellulose fibers which has a machine direction and a transverse direction orthogonal thereto in the web plane,

    A2 - hydroentangling the fibrous web by means of water jets directed onto the fibrous web in order to produce a hydroentangled fibrous web,

    A3 - drying the hydroentangled fibrous web,

    wherein in step A1 the proportion of the cellulose fibers in the fibrous web is chosen such that the hydroentangled nonwoven after the drying in step A3 contains at least 50% and
    at most 100% cellulose fibers, based on the mass of the hydroentangled nonwoven, and

    wherein steps A1 and A2 are carried out such that the hydroentangled nonwoven is imparted a characteristic plastic deformability in the transverse direction, which is characterised in that in a tensile test in the transverse direction according to ISO 1924-2:2008 carried out on the hydroentangled nonwoven after the drying in step A3, the non-linear proportion 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 the hydroentangled nonwoven after the drying in step A3 has a basis weight of at least 15 g/m² and at most 60 g/m².
12. The method according to claim 11, wherein a plurality of water jets is used to carry out the hydroentangling in step A2, wherein the water jets are arranged in at least one row transversely to the machine direction of the fibrous web,
    wherein the hydroentangling in step A2 is preferably effected by at least two rows of water jets directed onto the fibrous web, wherein preferably at least one row of the water jets acts on each of the two sides of the fibrous web.
13. The method according to any one of claims 11 or 12, wherein the drying in step A3 is effected at least in part by contact with hot air, by infrared radiation or by microwave radiation, and/or
    wherein the hydroentangled nonwoven produced according to this method is a hydroentangled nonwoven according to any one of claims 1 to 5.
14. The method according to any one of claims 11 to 13, wherein the step A1 of providing the fibrous web comprises the following sub-steps B1 to B3:

    B1 - producing an aqueous suspension comprising cellulose fibers,

    B2 - applying the suspension from step B1 to a circulating screen,

    B3 - dewatering the suspension through the circulating screen in order to form said fibrous web,

    wherein in step B1 the amount or the proportion of cellulose fibers is chosen such that the hydroentangled nonwoven after the drying in step A3 contains at least 50% and at most 100% cellulose fibers, based on the mass of the hydroentangled nonwoven,

    wherein said machine direction of the fibrous web is defined by the running direction of the screen in step B3 and said transverse direction is defined by the direction orthogonal thereto in the plane of the fibrous web, and

    wherein in step B2 the suspension is applied to the circulating screen at a speed which is lower than the speed of the circulating screen,

    wherein the aqueous suspension in step B1 preferably has a solids content of at most 3.0%, particularly preferably at most 1.0%, very particularly preferably at most 0.2% and in particular at most 0.05%, and/or

    wherein preferably the circulating screen of steps B2 and B3 is inclined upwards in the machine direction of the fibrous web against the horizontal by an angle of at least 3° and

    at most 40°, preferably by an angle of at least 50 and at most 30° and particularly preferably by an angle of at least 15° and at most 25°, and/or

    which preferably further comprises a step in which a pressure difference is generated between the two sides of the circulating screen in order to assist the dewatering of the suspension in step B3, wherein the pressure difference is particularly preferably generated by vacuum boxes or suitably shaped vanes.
15. The method according to any one of claims 11 to 14, which comprises a further step in which one or more additives are applied to the fibrous web, wherein the one or more additives are selected from the group consisting of alkylene chain dimers (AKD), acid anhydrides, in particular alkenyl succinic acid anhydrides (ASA), polyvinyl alcohol, waxes, fatty acids, starch, starch derivatives, carboxymethyl cellulose, alginates, chitosan, wet strength agents and substances for adjusting the pH, in particular organic or inorganic acids or alkalis, and mixtures thereof, and/or

    which comprises a further step in which one or more additives are applied to the fibrous web, wherein the one or more additives are selected from the group consisting of citrates, in particular trisodium citrate or tripotassium citrate, malates, tartrates, acetates, in particular sodium acetate or potassium acetate, nitrates, succinates, fumarates, gluconates, glycolates, lactates, oxyalates, salicylates, α-hydroxycaprylates, phosphates, polyphosphates, chlorides and hydrogencarbonates, and mixtures thereof, wherein

    the one or more additives are preferably applied between steps A2 and A3, or after step A3, followed by a further step of drying the fibrous web.

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