FILTER MATERIAL AND/OR FILLER MATERIAL FOR MOUTHPIECES FOR USE WITH SMOKING PRODUCTS OR HNB PRODUCTS, MOUTHPIECES AND CIGARETTE FILTERS COMPRISING SUCH A FILTER MATERIAL AND/OR FILLER MATERIAL, AND METHOD FOR MANUFACTURING SUCH A FILTER MATERIAL AND/OR FILLER MATERIAL

Abstract

The invention relates to a filter material and/or filler material for mouthpieces for use with smoking products or HNB products, the filter material and/or filler material being based on cellulose acetate filaments, at least parts of which are in the form of hollow cellulose acetate filaments. The invention also relates to a mouthpiece for use with smoking products or HNB products, the mouthpiece comprising a filter material and/or filler material of the type according to the invention. The invention also relates to a cigarette filter comprising such a filter material and/or filler material, and to a corresponding method for manufacturing a filter material and/or filler material for mouthpieces for use with smoking products or HNB products.

Description

The present invention relates to a filter material and/or filler material for mouthpieces for use with smoking products or HNB products as well as the use of such filter material and/or filler material in mouthpieces for smoking articles or in cigarette filters or mouthpieces for HNB products respectively. According to a further aspect, the invention relates to a method for manufacturing such a filter material and/or filler material.

Smoking products within the meaning of the present invention relate to traditional tobacco products, cigarettes in particular, but also to pipes and marijuana products as well as so-called heat-not-burn (HNB) products, vaping products and so-called hybrid products.

Mouthpieces for use with smoking products have different functions depending on the application. Firstly, mouthpieces can serve as a filter device, for example in order to draw harmful elements such as condensed substances like tar along with particulate matter entrained in a stream of tobacco smoke out of the smoke. This filtering function is in particular used in traditional tobacco applications. A corresponding mouthpiece can thereby be formed as an integral part of a cigarette or a cigarillo and thus form a “tip” on the cigarette or cigarillo.

Replaceable devices are another type of mouthpiece being, for example, replaceable filter elements able to be removed after use. Such mouthpieces are accommodated in suitable holders, e.g. a cigarette holder or a pipe mouthpiece.

One mouthpiece formed as an integral part of a cigarette is the cigarette filter. The cigarette filter is intended to inhibit the percentage of harmful substances such as condensate and gases in the cigarette's smoke. The filter additionally makes the smoke somewhat milder or more palatable for a large percentage of smokers. In a traditional filter cigarette, the filter is encased in filter wrap paper and connected to the tobacco roll with so-called tipping paper, whereby most industrially manufactured cigarettes are provided with a filter. Those who roll their own can purchase them in tobacco shops.

Numerous types of filter materials have already been used to, in particular, reduce the levels of substances in tobacco smoke before they reach the smoker's respiratory system. Yet in addition to removing large quantities of harmful elements, a satisfactory filter also needs to be effective without undesirably impeding the passage of air or smoke through the filter and thus necessitating an excessive drag on same. When used in tobacco smoke filters, however, the filter material must also not change the taste of the tobacco smoke by adding its own flavor.

A further important factor in the manufacture of a satisfactory tobacco smoke filter is that of its manufacture not being too complex so as not to excessively inflate the final price of the smoking product in which the filter is used.

However, the present invention relates less to filter materials for the above-described traditional tobacco applications but rather in particular to filter materials and/or filler materials for mouthpieces used in smoking products, whereby these filter materials and/or filler materials in particular have other functions other than simply a filtering function.

In other applications, a filtering function of the mouthpiece is by no means actually the main focus. This applies for example to heat-not-burn products (“HNB products”), which have become increasingly popular in recent years. In these devices, a portion of processed tobacco is heated by a heat source during use but not burned. Volatile tobacco components such as flavorings, nicotine, glycerin and water thereby vaporize and are entrained in the air which the user draws in through the HNB product. As the released substances cool, an aerosol is formed which is inhaled by the user.

Commercially available HNB products usually comprise a device consisting of a power supply which supplies a heating element and a separate consumable product consisting of a portion of processed tobacco, a supporting element such as for example a tubular cellulose acetate segment, a so-called cooling element disposed downstream in the direction of flow, for example in the form of a crimped polylactide film bundled into a cylinder with numerous axial channels, as well as a filter on the mouth side. The consumable products are inserted into the device prior to use such that the heating element heats up the portion of tobacco while the HNB product is being used.

For example, in a product from Philip Morris called IQOS/HEETS, the tobacco portion is pierced by a heating blade in the device. An IQOS/HEETS product refers to an IQOS device with its associated consumable HEETS product as marketed by Philip Morris. The consumable HEETS product is a heat-not-burn product in which the tobacco is simply heated instead of being burned.

A competitive product from BAT (“Glo”) heats the tobacco from the outside, whereby the so-called cooling element is replaced by a tube. In these devices as well, a portion of processed tobacco is heated by a heat source during use but not burned. Volatile tobacco components such as flavorings, nicotine, glycerin and water thereby vaporize and are entrained in the air which the user draws in through the HNB product. As the released substances cool, an aerosol is formed which is inhaled by the user.

The known consumable products for this application have the disadvantage that their mouth-side filters can heat up significantly due to their proximity to the heating element and due to the hot vapor produced during use of the HNB product.

In so-called hybrid products, an aerosol generator is first vaporized (propylene glycol, glycerine); cooling produces an aerosol. This aerosol is directed through a portion of processed tobacco and inhaled by the consumer. In such applications as well, the mouthpiece has the particular function of protecting the user-side end from heating up to an unpleasant degree for the user.

In contrast to conventional tobacco products which burn tobacco, it can be desirable in the case of HNB product consumables for the elements disposed downstream of the heated tobacco portion in the direction of flow such as the cooling element and the mouth-side filter to only have a low filtering effect with respect to condensed components such as tar since these components of smoke can occur in substantially smaller amounts.

The materials required to form a mouthpiece for smoking products thus need to be adapted, and in particular adaptable, to the physical properties of the smoke (temperature, flow profile, etc.) and to the chemical composition. Both conventional cigarette filters as well as HNB products in particular have a number of target parameters which need to be regulated or respectively met by the appropriate selection and configuration of the mouthpiece materials. This relates in particular to the following target parameters, to be briefly discussed below:

• • draw resistance
  • filtration performance
  • filter rod hardness/Filtrona hardness
  • visual appearance
  • production cost-effectiveness
  • smoke temperature

Filter rod hardness is an important target criterion for cigarette filters. It is typically indicated as the so-called Filtrona hardness. The Filtrona hardness is determined by vertically pressing the flat front end of a cylindrical rod 12 mm in diameter onto a horizontally positioned filter rod at a load of 300 g. The ratio of the compressed diameter to the initial diameter previously determined at first contact yields the Filtrona hardness percentage.

To be emphasized is that Filtrona hardness is only measured on a filter but not, however, on the underlying (raw) filter material.

The minimum limit of Filtrona hardness is approximately 88% and is geared toward market requirements. The Filtrona hardness of the cigarette filter can thereby preferably be set to approximately 88% to 95%, in particular approximately 90% to 93%.

In conventional cigarette filters, the Filtrona hardness is essentially determined by the fiber weight per unit of volume for a given filter diameter. The filament titer in particular only has a minor influence on the Filtrona hardness.

Occasionally, a stronger filter wrap paper or stronger tipping paper will also achieve a higher Filtrona hardness. Tipping paper is a paper in which either multiple filter elements are connected together or filter elements are connected to the tobacco rod. However, increasing the Filtrona hardness by using stronger filter wrap paper or stronger tipping paper has economic disadvantages since higher costs can be expected with this approach.

Associated with Filtrona hardness is the so-called “hot collapse,” in which filter hardness decreases during smoking. In a traditional cigarette, this can particularly occur when the filter is heated in the presence of moisture during one of the last puffs. This undesirable effect can also occur with HNB products.

In addition to a Filtrona hardness which is as constant and high as possible during use of a smoking product, the mouthpiece material should also exhibit a predefined or definable filtration performance. Filtration performance in terms of condensed matter (droplets, particles), also referred to as condensate or tar, is of interest with respect to conventional tobacco products as well as HNB products as the condensed matter contains a plurality of substances of unhealthy significance.

In conventional products, filtration performance (along with other influencing factors such as tobacco blend, ventilation, etc.) is selected so as to regulate the cigarette's “delivery” (the level of the smoke's constituents within the mainstream smoke). In many markets, legal regulations cap the “delivery” at an upper limit. Below the legal limit, the “delivery” can be adapted to consumer preferences.

In HNB products, the aerosol has much less condensed matter of negative health significance than is the case with conventional products. Yet since more desirable materials such as flavor substances and nicotine are likewise present in the condensate, the aim here is to select the lowest possible filtration performance without, however, allowing it to drop to zero.

To be noted with respect to the “draw resistance” target parameter is that consumers show a preference for a certain range of draw resistance when using a tobacco product. In conventional cigarettes, the filter (in addition to regulating the “delivery”) serves to regulate the cigarette's draw resistance.

In HNB products, however, the draw resistance contributed by the mouth-side filter (mouthpiece) should tend to be as low as possible since the other components of the HBN device, particularly the heated portion of tobacco and the device, already provide a high contribution to the draw resistance. A low filter (mouthpiece) draw resistance leads to degrees of freedom as relates to the other components of the HBN device, which is desirable.

Yet draw resistance and filtration performance are closely linked. Both can be reduced in a plurality of ways, although this frequently negatively affects other parameters.

For example, draw resistance and filtration performance can be reduced by reducing the length of the filter. But once the filter length becomes smaller than the filter diameter, processability becomes problematic. A shorter filter also leads to a shorter cooling section, which is problematic for the heat balance.

Alternatively or additionally thereto, draw resistance and filtration performance can be reduced by reducing the fiber weight in the filter material per volumetric content and/or the total denier. However, this has the disadvantage of decreasing the Filtrona hardness and possibly no longer being able to achieve the minimum hardness.

Alternatively or additionally thereto, draw resistance and filtration performance can be reduced by increasing the filament titer. At a constant filter diameter and a fixed fiber weight per unit of volume, filtration performance and draw resistance decreases with increasing filament titer, which is desirable in the case of HNB products compared to conventional products. Neither is the hardness negatively affected since, as stated above, Filtrona hardness only marginally depends on the filament titer.

To be noted with respect to the “visual appearance” target parameter is that the consumer prefers a mouthpiece having a flat, white cross-sectional area on the mouth side. There are, however, also products shaped into a tube on the mouth side.

To be noted with respect to the smoke temperature is that smoke temperature poses no problem in today's conventional products. Yet the smoke temperature is remarkably high in commercial HNB products, and uncomfortably high for some consumers. In addition, commercial HNB products require cooling in order to cool the vaporized components such that an aerosol of the gaseous components initially forms.

In commercially available HNB products, the distance from the heating element to the mouth end of the HNB product is certainly the most important parameter for cooling the aerosol. It is thus for example known to dispose a so-called cooling element downstream of the tobacco portion and the supporting element. The cooling element can be in the form of a crimped polylactide film or in the form of a cardboard tube, whereby—in addition to cooling—this element disposed downstream of the tobacco portion and the supporting element in particular also assumes the function of a spacer providing mechanical stability.

Lastly, the mouthpiece materials must satisfy the cost-effectiveness target parameter. There is particularly a need for suitable mouthpiece materials able to be produced with the lowest possible material usage and at the lowest possible processing costs.

Although conventional cigarette filters, which are usually made up of cellulose acetate filaments, ensure optimum filtration of the constituents in the smoke, these filter materials can often only be used to a limited extent in other applications, particularly in the case of HNB products or e-cigarettes, since in these applications, the filter materials or respectively mouthpiece materials need to assume other functions.

HNB products, as well as conventional smoking products, generally have the disadvantage of the user taking in the inhaled aerosol at a high temperature. This is sometimes unpleasant for the user. Particularly with HNB products, the mouthpiece materials thus have the task of cooling the aerosol at the lowest possible filtration performance.

But also in the case of traditional cigarettes, particularly so-called slim or ultra-slim cigarettes; i.e. small diameter cigarettes of e.g. 5.0 mm to 6.5 mm, the filter materials/mouthpiece materials need to provide—compared to filter materials for king-size cigarettes—reduced filtration performance, increased cooling and improved tactile properties (firm but not too stiff of a grip). Naturally, there is less smoke/flavor while burning than with a king-size cigarette. Low filtration performance is sought so as to not further reduce the flavor. If only the amount of filter material is reduced to that end, the filter hardness will eventually become insufficient.

At the same fiber density, filters for slim or ultra-slim cigarettes also have significantly higher draw resistance than king-size filters, which is generally undesirable.

For both HNB products as well as ultra-slim cigarettes, increasing the filament titer while maintaining the total titer has been proposed in order to achieve the desired reduced filtration performance in terms of condensable components such as tar as well as a sufficient filter hardness. Yet this approach has the disadvantage of such fiber materials of high filament titer having economic disadvantages on conventional spinning machines. In the production of conventional filter tow, a solution of approximately 30% cellulose-2,5-acetate in acetone is pressed through spinnerets, the acetone evaporated in a spinning chamber by blowing heated air on it, a multitude of filaments (1,000 to 35,000) then being gathered into a strip and crimped in a stuffer box. In the case of higher filament titers, a greater volume of solvent needs to be evaporated per filament which, due to the larger ratio of filament cross-sectional area to filament surface area, takes more time and results in slower spinning speeds.

On the basis of this problem, the present invention is based on the task of specifying a material suitable for a wide range of smoking product applications.

In particular, the present invention is based on the task of specifying a filter material having a low draw resistance and low filtration performance, wherein the filter material is able to achieve a sufficiently high enough Filtrona hardness which is as constant as possible when used in smoking products, and wherein the filter material is nevertheless able to be produced particularly economically.

The filter material should moreover be suitable for producing a filter having a uniform, white and flat front end on the mouth side.

Further desirable in this context is for the filter material to exhibit a selective filtration effect on phenols.

The filter material should in particular be suitable for reliably cooling a heated particle-laden gas so as to be able to reduce the temperature of the gas, aerosol or vapor taken in by the user from a smoking product.

The material should furthermore be suitable such that when used as a filter material for in particular slim or ultra-slim cigarettes, an adjustable draw resistance, and one which is reduced particularly in comparison to king-size filters, can be realized.

These and other tasks are solved by the subject matter of independent claim 1.

Accordingly, the invention relates in particular to a material for forming a mouthpiece for smoking products, whereby the material comprises a filler material based on cellulose acetate filaments which are at least in part formed as hollow cellulose acetate filaments. The filler material, formed in part as hollow cellulose acetate filaments, has a lower density and a higher fill value than conventional cellulose acetate filaments which are not of hollow design and as are typically used in cigarette filters. Providing such a filler material enables significantly increasing the performance able to achieved with the mouthpiece and the range of applications.

The term “hollow fiber” as used herein is in particular to be understood as a preferably cylindrical fiber having one or more continuous hollow spaces in cross section. The hollow fibers are preferably at least partially crimped. However, the invention is not limited to crimped hollow fibers but instead also relates to non-crimped fibers or their use respectively.

According to embodiment variants of the present invention, the hollow fibers are at least in part realized as multi-lumen hollow fibers. Compared to single-lumen hollow fibers, multi-lumen hollow fibers are significantly more kink-resistant, whereby particularly high Filtrona hardness can be achieved without increased material compaction.

The term “Filtrona hardness” as used herein is to be understood as the filter hardness determined according to the Filtrona principle. This principle relates to determining the filter hardness by vertically pressing the flat front end of a cylindrical rod 12 mm in diameter onto a horizontally positioned filter rod at a load of 300 g. The ratio of the compressed diameter to the initial diameter previously determined at first contact yields the Filtrona hardness percentage.

According to preferential embodiments of the present invention, the cellulose acetate filaments of hollow form exhibit an at least partially trilobal; i.e. three-armed star-shaped cross-sectional shape. Such a cross-sectional shape is well-suited when the cellulose acetate filaments are to have the largest possible specific surface area so as to enable e.g. high filtration capability along with simultaneous economical use of raw materials. Alternatively thereto, it is possible to obtain the desired large specific surface area using a bundle of extremely fine filaments of circular cross-section. However, other cross-sectional shapes for the hollow cellulose acetate filaments are also conceivable such as, for example, a four-sided cross-sectional shape.

The filter material and/or filler material of the present invention is economical to produce and can be processed alone or together with traditional non-hollow cellulose acetate filaments into a filter rod having suitable draw resistance and optimized filtering properties.

Because the filter and/or filler material according to the invention comprises a filler material based on cellulose acetate filaments which are at least partially in the form of hollow cellulose acetate filaments, a low draw resistance and a low filtration performance can be realized since the filaments of the filter and/or filler material of at least partially hollow cellulose acetate filament form have a small outer surface area in relation to the total fiber volume. Preferential here is for the filaments of the filter and/or filler material of at least partially hollow cellulose acetate filament form to exhibit as round of a cross section as possible.

In this context, being able to realize particularly high Filtrona hardness was surprisingly found with the filter material and/or filler material due to the filaments being of at least partially hollow cellulose acetate filament form. In fact, it was found that filters which are at least in part formed from hollow cellulose acetate filaments (hollow fibers) achieve the desired minimum Filtrona hardness at a lower fiber weight per unit of volume.

Due to being based on cellulose acetate filaments, the inventive filter material and/or filler material is suitable for producing a filter having a uniform, white and flat mouth-side front end, whereby a selective phenol filtration effect can furthermore also be realized.

In terms of the smoking and health dialogue, using a filter and/or filler material based on cellulose acetate filaments firstly enables producing filter rods, particularly for cigarettes, which have demonstrably outstanding properties relative to specific retention phenomena. A filter made from cellulose acetate thus filters harmful nitrosamines and phenols far more efficiently than condensate and nicotine. In addition, smokers rate the taste of today's customary tobacco blend such as e.g. “American Blend,” “German Blend” and “Virginia” combined with a filter rod made of cellulose acetate to be the most pleasurable. Another advantage of a cellulose acetate filter rod not to be underestimated can be found in the optical homogeneity of the filter's cut surfaces.

By the inventive filter material and/or filler material being at least partially formed from hollow cellulose acetate filaments serving as filler material, there can be a wide range of varying draw resistance and filtration performance in filter rods made from the inventive material.

It has in particular been shown that a filter material consisting at least partially of hollow cellulose acetate filaments exhibits an improved thermal cooling effect. It was determined that the use of hollow cellulose acetate filaments as filler material was still able to achieve a very low filtering effect; i.e. retention effect, for the suspended substances and gases to be removed. It is presumed that this effect is achieved by the surface or the flow of gas or air to be cleaned being changed by the hollow cellulose acetate filaments in such a way as to only marginally retain any potentially suspended matter in the gas/air. Another reason could be that the use of hollow cellulose acetate filaments is able to achieve a different, particularly advantageous filter material surface structure.

The inventive filter material and/or filler material further has the advantage of enabling an in particular adjustable cooling of a heated particle-laden gas (particularly aerosols) such that the temperature of the gas, aerosol or vapor taken in by the user of a smoking product or HNB product can be reduced in targeted manner. By varying the proportion of hollow cellulose acetate filaments in the filter and/or filler material, the desired cooling effect can thus be adapted specifically to the application.

It is further important to note that in the inventive filter material and/or filler material, the flow is essentially around and less through the hollow cellulose acetate filaments (=hollow fibers). From geometrical considerations, it is obvious that the fiber-to-fiber distances are thereby considerably larger than the lumen (hollow portion) of the hollow fiber. The viscosity of the aerosol (substantially air) then occasions taking the path of least resistance (i.e. flowing between the filaments and not through each individual filament).

In other words, the operative filtration surface is by no means maximized in the inventive filter material and/or filler material since there is no flow through the hollow cellulose acetate filaments in the filter and/or filler material.

In particular, the hollow cellulose acetate filaments can thus have kinks that close off the lumen of the hollow cellulose acetate filaments without this having an effect on the performance of the inventive filter and/or filler material as regards the set target parameters.

Particularly to be noted in this context is that the hollow cellulose acetate filaments designed as hollow fibers do not need to be continuously hollow but rather can also be partially closed off by kinks. They can also deviate from an ideal circular shape.

Embodiments of the invention provide for the hollow cellulose acetate filaments of the filter material and/or filler material to serve on the one hand as a supporting material and on the other hand as cooling material. By the hollow cellulose acetate filaments simultaneously serving as a supporting material, particularly compact mouthpieces can be realized which thereby do not necessitate increasing the dimensions of the smoking product.

It is for example conceivable for the filter material and/or filler material to exhibit adjoining areas of hollow cellulose acetate filaments and non-hollow cellulose acetate filaments in the longitudinal direction of the mouthpiece. A mixture of hollow and non-hollow cellulose acetate filaments would also be conceivable. Alternatively or additionally thereto, the hollow and non-hollow cellulose acetate filaments can be arranged in layers and then crimped. Doing so enables the largest possible area of hollow cellulose acetate filaments serving as cooling material, whereby there is better cooling off of the particle-laden gas.

The filter material and/or filler material can be introduced into the smoking product in such a way that the hollow cellulose acetate filaments in particular are arranged essentially longitudinally to the direction of flow of the particle-laden gas or aerosol. So doing can thus achieve the filter and/or filler material only giving rise to a reduced drop in pressure when the user sucks on the mouthpiece so that the user does not perceive the sucking action as arduous or objectionable. By varying the alignment of the hollow cellulose acetate filaments with respect to the direction of flow of the particle-laden gas or aerosol, the draw resistance of the filter material and/or filler material can be varied over a wide range and adapted to the respective application.

Varying the proportion of hollow and non-hollow cellulose acetate filaments in the filter and/or filler material and/or varying the alignment of the hollow and non-hollow cellulose acetate filaments with respect to the direction of flow of the particle-laden gas or aerosol in the filter and/or filler material enables not only the cooling and filtration performance to be regulated but also the draw resistance of the filter material and/or filler material.

It is alternatively provided for the filter and/or filler material to only consist of hollow cellulose acetate filaments. The filter and/or filler material is then accorded optimal cooling efficiency at reduced filtration performance.

A further embodiment of the inventive filter material and/or filler material provides for the filter and/or filler material to be arranged as a separate segment in front of the mouthpiece in the direction of flow of the particle-laden gas or aerosol. The separate segment can be of a variety of shapes. While a cylindrical shape is described as a preferential example, the invention is not to be limited thereto. Conventional smoking products are usually of substantially cylindrical design. The separate segment can thereby furthermore be arranged ahead of any possible filter in the direction of flow of the particle-laden gas. The filter and/or filler material serving as a cooling device and formed as a separate segment can for example consist entirely of hollow cellulose acetate filaments.

It is also conceivable for the separate segment to comprise a wrapping made of for example paper or a type of housing so that the hollow cellulose acetate filaments serving as cooling material can be encapsulated. The wrapping or housing respectively has an inlet opening and an outlet opening for the particle-laden gas/aerosol through which it flows due to the suction created by the user's mouthpiece. The hollow cellulose acetate filaments serving as cooling material can optionally also be affixable in or respectively on the smoking product, e.g. in encapsulated form. In this way, a user has the option of only cooling the particle-laden gas when the user deems it necessary to do so.

As already stated, particularly the draw resistance of a filter rod formed from the inventive filter material can be varied over a much larger range by varying the proportion of hollow cellulose acetate filaments in the filter material.

In summary, it can thus be stated that by using a filter material which at least partially consists of hollow cellulose acetate filaments, there is a wide range over which the draw resistance and filtration performance can be adapted to the respective requirements, and done so clearly more flexibly than is the case with conventional cellulose acetate filament-based filter materials. A cooling effect can moreover be variably regulated.

The present invention in particular allows mouthpieces or filters respectively to be formed from cellulose acetate which is normally in the form of a strand of essentially longitudinal endless filaments, wherein the endless filaments are preferably crimped such that short sections of the individual filaments are irregularly arranged in non-parallel, converging and diverging directions compared to the predominantly longitudinal direction of the strand.

In one possible embodiment of the filter material according to the invention, the surface structure of the filter material can be varied by the use of particularly crimped cellulose acetate filaments. The crimp index of the cellulose acetate filaments is preferably between 10% and 60%, and particularly between 20% and 50%.

The crimp index I_x is a measure of crimp intensity. The crimp index of a filter tow is determined by a tensile test (force/strain relationship). It is defined as the ratio of the stretched length L₂ under the test load minus the initial length to the initial length under preload L₁:

I_x=(L₂−L₁)/L₁*100%

The test load is thereby 25 N and the preload 2.5 N. The clamping length is 250 mm. The crimp index is determined in the tensile test at a constant strain rate of 300 mm/min on a G02 device from the Borgwaldt GmbH company in Hamburg. Ten individual measurement values are recorded per measurement. The test is performed in the standard climate of 20° C. with 60% relative humidity.

The inventive filter material is preferably in the form of a filter tow consisting of endless cellulose acetate filaments, and particularly cellulose-2,5-acetate filaments, which have been crimped in a stuffer box. To produce the filter tow, a solution of approximately 30% cellulose-2,5-acetate in acetone is pressed through special spinnerets, the acetone evaporated in a spinning chamber by blowing heated air on it, a multitude of filaments (1,000 to 35,000) then being gathered into a strip and crimped in a stuffer box. The product is then dried, filled into storage containers and ultimately pressed into bales weighing between 300 and 600 kg.

Used to spin the spinning solution are spinnerets designed to spin hollow cellulose acetate filaments and/or cellulose acetate staple fibers.

After the filter tow bales have been transported to the filter or cigarette manufacturer, the filter tow is removed from the bales and processed into filter rods on a filter rod machine as described in printed publication U.S. Pat. No. 5,460,590 A, for example. The filter tow is thereby stretched in a stretching device, provided with an additive serving to bond the filaments and then, after forming a three-dimensional roving, is fed into the formatting unit via an inlet funnel where it is cross-axially compressed, wrapped in paper and cut to the final length of the filter rods.

The additive applied to bond the filaments can be a high-boiling solvent for cellulose acetate such as glycerol triacetate (triacetin), for example, which briefly solubilizes the surface of the filaments after being applied. Wherever two filaments happen to touch, a permanent bonding point occurs some time thereafter as the excess additive migrates into the fiber surface, whereby the previously liquid drops of solution solidify. Due to the aforementioned migration of the hardener, mechanically strong, three-dimensionally crosslinked filter rods are obtained after a storage period of less than an hour, said filter rods also referred to as “spatial filters” and having a low packing density of typically 20 mg/ml to 90 mg/ml, preferably 30 to 70 mg/ml and more preferentially 40 to 60 mg/ml. Due to their hardness, these filter rods can be processed on modern cigarette machines at high speeds without difficulty.

Tests have shown that the use of hollow cellulose acetate filaments in the filter material can reduce the filtration performance of spatial filters while maintaining the specifications such as length, diameter, draw resistance and filament titer, and increase the cooling efficiency.

By accordingly increasing the proportion of hollow fibers (hollow-shaped cellulose acetate filaments) in the filter material, the draw resistance can be kept in the required low range without increasing the filament titer despite the increase in cooling efficiency and the decrease in filtering performance.

According to realizations of the inventive filter material, it is thus in particular provided for the percentage of hollow-shaped (hollow) cellulose acetate filaments in the filter material to be between 20 to 100% and preferably between 40 to 100% and more preferentially—depending on the application—between 70 to 100%.

In particular, the hollow portion in the filter material is preferably 25 to 90% and preferentially 50 to 80%. This hollow portion makes a crucial contribution to the filtration performance on the one hand and to reducing the draw resistance on the other, which is only possible due to an appropriate proportion of hollow fibers in the filter material but cannot be realized with closed filaments. The hollow portion thereby corresponds to the ratio of “hollow” area of the filter material to the “total” cross-sectional area of the fibers.

To be noted in this context is that the inventive filter material is also in particular characterized by the filament diameter of the cellulose acetate filaments being significantly larger than the filament diameter of other (synthetic) hollow fibers having filament diameters ranging between 10 and 30 μm. In contrast thereto, the filament diameter of the hollow cellulose acetate filaments ranges between 30 to 150 μm (outer diameter), and preferably between 50 to 120 μm (outer diameter) and more preferentially between 60 to 100 μm (outer diameter). The hollow portion can in this way be increased and thus the specific filtration performance of the inventive filter material and/or filler material significantly decreased while at the same time the cooling efficiency of the inventive filter material and/or filler material increased.

The invention further relates to a cigarette filter made from a filter material of the aforementioned type.

According to non-limiting embodiments, either a thermoplastic cellulose ester fiber material or, in the case of a non-thermoplastic cellulose ester, a water-soluble adhesive can be used to manufacture a filter according to the invention. In the first case of a thermoplastic cellulose ester fiber material, a distinction can be made between two cases. In the first case, the fiber material is produced from a naturally thermoplastic cellulose ester such as, for example, cellulose acetate butyrate. No further measures are needed here to process the filter tow into the inventive filters. With a non-thermoplastic base polymer such as cellulose-2,5-acetate, for example, same needs to be thermoplasticized by the addition of a suitable plasticizer.

To produce the inventive filter, a filter tow is pulled from a bale, spread out pneumatically and stretched pursuant to the method customary for spatial filters.

Within the context of the inventive teaching, the acetate weight can be a maximum of 5 mg per mm of filter length and at least about 2 mg per mm of filter length and is in particular approximately 3 to 4 mg per mm of filter length. If the maximum value of 5 mg per mm of filter length is exceeded, such a product is then not adequately economical. Preferably, a minimum value of about 2 mg per mm of filter length is maintained. According to the prior art, falling short of this value results in no longer being able to maintain the desired minimum 88% cigarette filter hardness.

Within the context of the inventive teaching, the draw resistance can be a maximum of 2 mm daPa per mm of filter length and at least approximately 0.1 daPa per mm of filter length and is in particular 0.2 daPa to 1 daPa per mm of filter length. A draw resistance of 0.3 daPa to 0.7 daPa per mm of filter length is particularly preferential. A minimum value of 0.3 daPa per mm of filter length is preferably maintained. According to the prior art, falling short of this value results in no longer being able to maintain the desired minimum 88% cigarette filter hardness.

Several aspects essential to the invention are summarized below:

According to a first aspect, the invention relates to a filter material and/or filler material for mouthpieces for use with smoking products or HNB products, wherein the filter and/or filler material are cellulose acetate-based filaments which are at least in part formed as hollow and/or tubular cellulose acetate filaments.

According to one embodiment variant of the filter material and/or filler material, the cellulose acetate filaments comprise hollow and in particular crimped endless cellulose acetate filaments and/or hollow and in particular crimped and cut endless cellulose acetate filaments.

According to one embodiment variant of the filter material and/or filler material, the crimp index of the cellulose acetate filaments is between 10% and 60%, particularly between 20% and 50%.

According to one embodiment variant of the filter material and/or filler material, the cellulose acetate filaments are formed from a thermoplastic cellulose material, wherein the cellulose acetate filaments contain same in even distribution, provided a plasticizer is incorporated, and/or wherein a water-soluble adhesive is present on the surface of the cellulose acetate filaments.

According to one embodiment variant of the filter material and/or filler material, when a plasticizer is used, the plasticizer content is between 1% and 40%.

According to one embodiment variant of the filter material and/or filler material, when a plasticizer is used, same is triacetin, triethylene glycol diacetate and/or citric acid diethyl ester.

According to one embodiment variant of the filter material and/or filler material, the cellulose acetate filaments have a fineness of between 5 and 30 denier, preferably between 10 and 25 denier, and more preferentially between 15 to 20 denier.

According to one embodiment variant of the filter material and/or filler material, the total titer of the filter and/or filler material is between 4,000 and 40,000 denier and preferably between 6,000 and 30,000 denier.

According to one embodiment variant of the filter material and/or filler material, the hollow portion in the filter material and/or filler material—in relation to a section orthogonal to the fibers of the filter and/or filler material—amounts to 25% to 90% and preferably 50% to 80%.

According to one embodiment variant of the filter material and/or filler material, the filament diameter of the cellulose acetate filaments ranges between 30 to 150 μm (outer diameter), and preferably between 50 to 120 μm (outer diameter), and more preferentially between 60 to 100 μm (outer diameter).

According to one embodiment variant of the filter material and/or filler material, the mass fraction of hollow cellulose acetate filaments is between 20 to 100%, preferably 50 to 100%, and more preferentially 70 to 100%.

According to one embodiment variant of the filter material and/or filler material, the hollow cellulose acetate filaments are mutually distanced from one another in an irregular arrangement, whereby the cellulose acetate filaments are crosslinked, and whereby the connecting cellulose acetate filaments are entwined and/or entangled with one another.

According to one embodiment variant of the filter material and/or filler material, a binder, in particular an organic or inorganic binder, is further provided for binding the cellulose acetate filaments.

According to a further aspect, the present invention relates to a mouthpiece for use with smoking products or HNB products, wherein the mouthpiece comprises a filter material and/or filler material of the aforementioned inventive type.

According to a further aspect, the present invention relates to a cigarette filter or a cigarette filter element having a filter material and/or filler material of the afore-mentioned inventive type.

According to embodiment variants of the cigarette filter or cigarette filter element respectively, at least one feature from among the following features is realized:

• • the fiber density of the filter material and/or filler material is between 10 to 70 kg per m³ and preferably between 20 to 70 kg per m³ and more preferentially between 40 to 60 kg per m³;
  • the cigarette filter or cigarette filter element has a Filtrona hardness of at least 88% and preferably a Filtrona hardness of 88% to 95% and more preferentially a Filtrona hardness of 90% to 93%;
  • the cigarette filter or cigarette filter element has a draw resistance of at least 0.1 daPa per mm of filter length and preferably a draw resistance of 0.2 daPa to 1.0 daPa per mm of filter length and more preferentially a draw resistance of 0.3 daPa to 0.7 daPa per mm of filter length;
  • the filter material and/or filler material comprises a plasticizer, wherein the plasticizer content is between 1% to 40%.

According to embodiment variants of the cigarette filter/cigarette filter element, an in particular capsule-shaped or capsule-like flavor release element is further incorporated into the filter material and/or filler material.

According to embodiment variants of the cigarette filter/cigarette filter element, in addition to the hollow cellulose acetate filaments, the cigarette filter or cigarette filter element respectively also comprises solid cellulose acetate filaments.

According to a further aspect, the present invention relates to the use of the inventive filter and/or filler material in smoking products or in HNB products.

According to a further aspect, the present invention relates to a method for manufacturing a filter material and/or filler material for mouthpieces for use in smoking products or HNB products, wherein the filter material and/or filler material preferably consists of cellulose acetate filaments and/or cellulose acetate staple fibers, wherein a solution of cellulose acetate having an acetyl value of at least 53% in acetone is pressed through a spinneret having multiple openings, and whereby the cellulose acetate filaments are subsequently cut into cellulose acetate staple fibers as needed, and whereby a multitude of the cellulose acetate filaments and/or cellulose acetate staple fibers thus obtained are gathered into a filter tow which is potentially crimped as applicable, wherein the spinneret through which the solution of cellulose acetate is pressed is designed such that hollow cellulose acetate filaments are spun.

Claims

1. A method for manufacturing a filter material and a filler material for mouthpieces for use in smoking products or HNB products consisting of cellulose acetate filaments and/or cellulose acetate staple fibers, the method comprising the steps of:

obtaining a solution of cellulose acetate having an acetyl value of at least 53% in acetone;

pressing the solution of cellulose acetate through a spinneret having multiple openings;

cutting the cellulose acetate filaments into the cellulose acetate staple fibers;

forming a multitude of the cellulose acetate filaments and cellulose acetate staple fibers into a filter tow, wherein the filter tow is crimped,

wherein the spinneret through which the solution of cellulose acetate is pressed is configured such that hollow cellulose acetate filaments are spun, wherein a hollow portion in the filter material and the filler material in relation to a section orthogonal to the cellulose acetate staple fibers of the filter material and filler material amounts to 25% to 90%, and wherein the a filament diameter of the cellulose acetate filaments ranges is 60 μm to 100 μm.

2. The method according to claim 1,

wherein a crimp index of the cellulose acetate filaments is 10% and 60%.

3. The method according to claim 1,

wherein the cellulose acetate filaments include a plasticizer in even distribution thereof; and

wherein a water-soluble adhesive is present on a surface of the cellulose acetate filaments.

4. The method according to claim 1,

wherein the cellulose acetate filaments and the cellulose acetate staple fibers comprise a plasticizer, and wherein a plasticizer content of the plasticizer is 1% and 40%.

5. The method according to claim 1,

wherein the cellulose acetate filaments and the cellulose acetate staple fibers comprise a plasticizer, and wherein the plasticizer is triacetin, triethylene glycol diacetate, citric acid diethyl ester, or combinations thereof.

6. The method according to claim 1,

wherein the cellulose acetate filaments have a fineness of 5 denier and 30 denier.

7. The method according to claim 1,

wherein a total titer of the filter and filler material is 4,000 denier and 40,000 denier.

8. The method according to claim 1,

wherein a mass fraction of the hollow cellulose acetate filaments is 20% to 100%.

9. The method according to claim 1,

wherein the hollow cellulose acetate filaments are mutually distanced from one another in an irregular arrangement, and wherein the cellulose acetate filaments are crosslinked, and wherein the cellulose acetate filaments are entwined and entangled with one another.

10. The method according to claim 1,

wherein a binder is provided for-binding the cellulose acetate filaments.

11. A mouthpiece for use with the smoking products or HNB products, wherein the mouthpiece comprises a filter material and filler material manufactured in accordance with the method according to claim 1.

12. The mouthpiece according to claim 11,

wherein a fiber density of the filter material and the filler material is 10 to 70 kg per m3; and

wherein the mouthpiece has a Filtrona hardness of at least 88% and

wherein the mouthpiece has a draw resistance of at least 0.1 daPa per mm of a filter length of the mouthpiece.

13. The mouthpiece according to claim 11,

wherein a capsule-shaped or capsule-like flavor release element is further incorporated into the filter and filler material.

14. The mouthpiece according to claim 11,

wherein the filter material and filler material comprises solid cellulose acetate filaments.

15. A cigarette filter or cigarette filter element, comprising a filter material and filler material manufactured in accordance with the method according to claim 1.

16. The cigarette filter or cigarette filter element according to claim 15,

wherein a fiber density of the filter material and the filler material is 10 to 70 kg per m3; and,

wherein the cigarette filter or cigarette filter element has a Filtrona hardness of at least 88% and

wherein the cigarette filter or cigarette filter element has a draw resistance of at least 0.1 daPa per mm of a filter length of the cigarette filter or cigarette filter element.

17. The cigarette filter or cigarette filter element according to claim 15,

wherein a capsule-shaped or capsule-like flavor release element is incorporated into the filter and filler material.

18. The cigarette filter or cigarette filter element according to claim 15, wherein the cigarette filter or cigarette filter element comprises solid cellulose acetate filaments.