US20250176618A1

US20250176618A1 - Filter element for mouthpieces, mouthpiece for use in smoking products or hnb products, and cigarette filter

Info

Publication number: US20250176618A1
Application number: US18/836,965
Authority: US
Inventors: Eckart Schütz; Uwe Schäffner; Martin Moser
Original assignee: Cerdia International GmbH
Current assignee: Cerdia International GmbH
Priority date: 2022-02-08
Filing date: 2023-02-01
Publication date: 2025-06-05
Also published as: WO2023151997A1; JP2025505215A; EP4475696A1; KR20240138563A; AR128476A1; CN118660640A; DE102022102862A1; EP4475696B1

Abstract

A filter element for mouthpieces for use with smoking or HNB products can include a filter body made of a tow material formed by a plurality of individual threads of cross-linked and crimped cellulose acetate filaments having a multilobal, polygonal or Y-shaped cross-sectional geometry. The cellulose acetate filaments of the tow material have a uniform filament titre, which can be predetermined or predefinable, in a range of less than or equal to 10 denier (11.1 dtex) and greater than or equal to 5 denier (5.5 dtex); and a specific fibre weight of less less than or equal to 2.5 mg per mm of filter element length and greater than or equal to 1.0 mg per mm of filter element length. The tow material has a total titre in a range of less than or equal to 10,000 denier (11.1 kdtex) and greater than or equal to 5,000 denier (5,555.5 dtex).

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a U.S. National phase of International Patent Application No. PCT/EP2023/052412, filed Feb. 1, 2023, which claims priority to German Application No. 10 2022 102 862.3, filed Feb. 8, 2022, the disclosures of with are hereby incorporated by reference in their entireties.

FIELD OF THE DISCLOSURE

The invention relates to a filter element for mouthpieces for use with smoking products or HNB products as well as the use such a filter element in mouthpieces for smoking products or in cigarette filters or mouthpieces for HNB products respectively.
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.

BACKGROUND

Depending on the application, mouthpieces for using smoking products have different functions. For example, mouthpieces can on the one hand serve as filter devices in pulling out harmful components from a stream of tobacco smoke such as condensed substances, particularly tar, as well as particulate matter entrained in the stream of smoke. This filtering function is in particular used with conventional tobacco applications. A corresponding mouthpiece can thereby be formed as an integral part of a cigarette or a cigarillo and thus form a “support” on the cigarette/cigarillo.
An example of another type of mouthpiece relates to interchangeable devices such as replaceable filter elements able to be detached 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 reduce a percentage of harmful substances such as condensate and gas in the smoke of the cigarette. In addition, the filter makes the smoke milder or more palatable for a large percentage of smokers. In a conventional filter cigarette, the filter is encased in filter wrap paper and connected to the tobacco rod via so-called tipping paper, whereby most industrially manufactured cigarettes are provided with a filter.
There are numerous types of filter materials already in use, particularly in order to lower the substances in tobacco smoke before they reach the respiratory system of the smoker. Yet in addition to removing large quantities of harmful substances, 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 it. When using tobacco smoke filters, the filter material must however also not change the taste of the tobacco smoke by adding its own flavor.

DETAILED DESCRIPTION

The present invention not only relates to filter materials for the aforementioned conventional tobacco applications but in particular also to filter materials and/or filter elements for mouthpieces used in smoking products, whereby these filter elements in particular have other functions other than simply a filtering function.
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

Filter rod hardness is an important target criterion for cigarette filters. It is usually indicated as so-called Filtrona hardness. 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 Filtrona hardness is particularly influenced by the triacetin sprayed onto all cigarette filters.
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, Filtrona hardness is essentially dictated by the fiber weight per unit of volume for a given filter diameter. In particular, the filament titer only has a minor influence on the Filtrona hardness.
Occasionally, a higher Filtrona hardness can also be achieved by means of a stronger filter wrap paper or stronger tipping paper. Tipping paper is a paper with which either multiple filter elements are coupled together or filter elements are coupled 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 the filter hardness decreases during smoking. This can particularly occur with a traditional cigarette 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 titer. This, however, 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.
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/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 unsatisfactory.
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 slim or 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 like tar as well as a sufficient filter hardness. Yet this approach has various disadvantages
Cellulose-2,5-acetate is widely used today to produce filter rods for filter elements, respectively cigarette filters. From the smoking and health standpoint, it has demonstrably outstanding properties relative to specific retention phenomena. A filter made from cellulose acetate filters harmful nitrosamines and phenols far more efficiently than condensate and nicotine. In addition, smokers rate the taste of the tobacco blend smoke combined with a cellulose acetate filter element to be the most palatable. A further advantage of a filter element made from cellulose-2,5-acetate not to be underestimated can be found in the visual homogeneity of the filter's cut surfaces.
However, notwithstanding their undeniable market dominance, cellulose-2,5-acetate filter elements have some serious disadvantages: Filter rods have explicitly defined draw resistance and filtration performance by virtue of the structural physical stipulations.
The particle filtration or even condensate retention of a normal cellulose-2,5-acetate filter element is a function of filament titer (fiber fineness), filter diameter, draw resistance and filter length.
Given a normal filter diameter of 7.8 mm and a filter length from 21 to 25 mm, it becomes problematic when significantly more than 50% filter performance is required during the production of filter elements, as is necessary when engineering ultra-light cigarettes.
The same also applies figuratively to filter elements for slim or ultra-slim cigarettes. Since the smoke in a filter element flows parallel to the fiber direction, such a filter element can only be obtained by significantly reducing the filament titer, which would simultaneously result in a significant increase in draw resistance with no change in the total titer.
Total titer and filament titer must therefore be reduced in equal measure, with the consequence of the filter element hardness being drastically decreased, particularly during smoking. This phenomenon is referred to by those skilled in the art as “hot collapse” and is generally considered undesirable.
The present invention is based on the task of specifying a filter element particularly for so-called slim or ultra-slim cigarettes; i.e. small diameter cigarettes of e.g. 5.0 mm to 6.5 mm, wherein the filter element exhibits a sufficient filter hardness despite reduced filtration performance and increased cooling. The filter element should furthermore be able to realize a draw resistance which is adjustable and in particular reduced in comparison to king-size filters.
The invention solves this task with a filter element having the features of independent claim 1, whereby advantageous further developments of the inventive filter element are specified in the dependent claims.
Accordingly, the invention relates in particular to a filter element for mouthpieces for use with smoking products or HNB products, wherein the filter element has a filter body made from a tow material. The tow material is formed by a plurality of monofilaments of crosslinked and crimped cellulose acetate filaments, whereby the cellulose acetate psfilaments in particular exhibit a multilobal or polygonal and preferably Y-shaped cross-sectional geometry.
The filter element according to the invention is in particular characterized by a specific filament titer being selected for the cellulose acetate filaments of the tow material. The filament titer preferably lies in a range of from less than or equal to 10 denier and greater than or equal to 5 denier.
Moreover, a relatively small total titer is selected for the tow material of the inventive filter element, preferably a total titer in a range of from less than or equal to 10000 denier and greater than or equal to 5000 denier.
Surprisingly found here was that despite the relatively low filament titer of less than or equal to 10 denier and the relatively low total titer of less than or equal to 10000 denier, the entirely unwanted hot collapse phenomenon can be effectively prevented even in the case of slim or ultra-slim cigarettes when a relatively low value of less than or equal to 2.5 mg per mm of filter element length is selected for the specific fiber weight of the cellulose filaments of the tow material; i.e. for the so-called specific acetate weight.
With the specifications relating to the relatively low filament titer, relatively low total titer and the relatively low specific fiber weight of the cellulose acetate filaments (acetate weight), a filter element can be realized which achieves a filter performance as required in the engineering of slim or ultra-slim cigarettes without a significant increase in draw resistance. These parameters enable significantly increasing the performance and range of applications achievable with the filter element.
In particular, the cellulose acetate filaments of the tow material 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 high filtration capability—should that be desired, as is the case with conventional cigarettes, for example—along with simultaneous economical use of raw materials.
Alternatively thereto, it is possible to obtain a desired large specific surface area using a bundle of extremely fine filaments of for example circular cross section. However, other cross-sectional shapes are also conceivable for the cellulose acetate filaments such as, for example, a multilobal, polygonal or X-shaped cross-sectional shape.
The tow material of the inventive filter element is formed from continuous stuffer box-crimped cellulose acetate filaments. A solution of approximately 30% cellulose-2,5-acetate in acetone is thereby pressed through spinnerets, the acetone evaporated in a spinning chamber, a plurality of cellulose acetate filaments (5000 to 10,000) gathered into a strip and then crimped in a stuffer box.
The product is thereafter dried, filled into storage containers, and finally pressed into bales weighing between 300 and 600 kg.
After the filter tow bales have been transported to the filter or cigarette manufacturer, the filter tow is taken from the bales and processed into filter rods on a filter rod machine. The filter tow is thereby stretched in a stretching device, provided with an additive serving to bond the filaments and, after forming a three-dimensional roving, subsequently introduced through an inlet funnel into the formatting unit where it is cross-axially compressed, wrapped in paper and cut to the final length of the filter element.
The additive applied to bond the filaments is usually 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 droplets of cellulose-2,5-acetate solidify in the additive. Due to the aforementioned migration of the hardener, mechanically strong, three-dimensionally crosslinked filter rods of low packing density are obtained after a storage period of less than an hour which, due to their hardness, are able to be processed on modern cigarette machines at high speeds without difficulty.
Selecting a relatively low filament titer, a relatively low total titer and an acetate weight of less than or equal to 2.5 mg per mm of filter element length for the tow material of the filter element according to the invention enables realizing a filter element which achieves the desired filtration performance in terms of condensable components yet still has sufficient filter hardness while maintaining the low total titer.
According to embodiments of the inventive filter element, the cellulose acetate filaments of the tow material's monofilaments are at least partially formed as hollow and/or tubular cellulose acetate filaments.
Particularly to be understood by hollow/tubular cellulose acetate filaments are preferably cylindrical filaments exhibiting one or more continuous cavities when viewed in cross section.
Such hollow fibers can be at least partly designed as multi-lumen hollow fibers. Compared to “solid” cellulose acetate filaments, single-lumen or multi-lumen tubular cellulose acetate filaments are considerably more resistant to kinking, whereby particularly high Filtrona hardness can be realized without increased material compression.
Because the inventive filter element comprises a filter body able to be based at least in part on cellulose acetate filaments which are at least partially formed as hollow cellulose acetate filaments, a low draw resistance and low filtration performance can be realized since the filaments of the filter element at least partially formed as hollow cellulose acetate filaments have a small external surface area in relation to the total fiber volume.
In this context, it was surprisingly found that due to the filaments being partially formed as hollow cellulose acetate filaments, particularly high Filtrona hardnesses can be achieved with the filter element.
In fact, it became evident that filter elements which are at least partially formed from hollow cellulose acetate filaments (hollow fibers) achieve the desired minimum Filtrona hardness with a lower fiber weight per unit of volume.
Since the inventive filter element is based on cellulose acetate filaments, the inventive filter element is designed to form a uniform, white and smooth mouth-side front end for a tobacco rod of for example a cigarette, whereby a selective phenol filtration effect can further be realized.
The use of a filter element based on cellulose acetate filaments for one thing enables producing filter rods particularly for cigarettes which, from the smoking and health standpoint, have shown demonstrably outstanding properties relative to specific retention phenomena.
A filter made from cellulose acetate 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 palatable. A further advantage of a cellulose acetate filter rod not to be under-estimated can be found in the visual homogeneity of the filter's cut surfaces.
By the inventive filter element being at least partially formed from hollow cellulose acetate filaments serving as filler material according to embodiments, 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 hollow cellulose acetate filaments changing the surface area or the flow rate of the gas or air to be cleaned in such a way that there is only marginal retention of 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 element further has the advantage of enabling in particular variable cooling of a heated particle-laden gas (particularly aerosol) such that the temperature of the gas, aerosol or vapor taken in by the user of a smoking product or HNB product can be selectively reduced. 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 element, 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 the path of least resistance to be taken (i.e. flow between the filaments and not through each individual filament).
In other words, the operative filtration surface is by no means maximized in the embodiment of the inventive filter element since there is no flow through the hollow cellulose acetate filaments in the tow 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 realized 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 tow material to serve on the one hand as a support material and on the other hand as cooling material. By the hollow cellulose acetate filaments simultaneously serving as a support material, particularly compact filter elements can be realized which do not thereby necessitate increasing the dimensions of the smoking product.
The term “Filtrona hardness” as used herein refers to the filter hardness as determined according to the Filtrona principle. Under this principle, the filter 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.
The filter element, or filter rod hardness respectively, is an important target criterion particularly for cigarette filters. It is typically indicated as the so-called Filtrona hardness. To hereby be emphasized is that Filtrona hardness is only measured on a filter element but not, however, on the underlying (raw) filter material, thus the tow material. The Filtrona hardness of a filter element is particularly influenced by the amount of triacetin which is/can be sprayed onto the filter element.
The minimum limit of Filtrona hardness is approximately 88% and is geared toward market requirements. The Filtrona hardness of the filter element can thereby preferably be set to approximately 88% to 95%, in particular approximately 90% to 93%.
Preferential embodiments of the inventive filter element provide for the filter body to be realized in particular as a filter rod and preferably with a diameter of between approximately 6 mm and approximately 4 mm and particularly a diameter between approximately 5.5 mm and approximately 5.0 mm and preferably a diameter of approximately 5.35 mm, wherein at least part of the filter body is wrapped in a paper or paper-like material.
The Filtrona hardness of the filter element should preferably be greater than 85% in this embodiment and, in particular, greater than 90%.
Filtrona hardness is particularly dictated by the acetate weight for a given filter element diameter, whereby the filament titer of the tow material's cellulose acetate filaments only has a minor influence on the Filtrona hardness.
Configurations of the inventive filter element provide for the filter body to have an acetate weight amounting to a maximum 2.5 mg/mm filter element length.
The Filtrona hardness of the filter element can also be achieved by means of a stronger filter wrap paper or stronger tipping paper.
Tipping paper is a paper with which either multiple filter elements are coupled together or a filter element is coupled to a tobacco rod. However, increasing the Filtrona hardness of the filter element by using stronger filter wrap paper or stronger tipping paper has economic disadvantages since higher costs can be expected with this approach.
Associated with the Filtrona hardness of the filter element is the so-called “hot collapse,” in which the filter hardness decreases as the filter element is being used; i.e. the filter element being used with smoking or HNB products. This phenomenon can particularly occur with a traditional cigarette when the filter element is heated in the presence of moisture during one of the last puffs, although this undesirable effect can also occur with HNB products.
It has been shown in this context that the degree to which the Filtrona hardness reduces due to the “hot collapse” phenomenon can be significantly reduced when a tow material having the cited low filament titer, cited low total titer and low acetate weight is used as the base material of the inventive filter element.
The tow material of the filter body of the inventive filter element preferably has a mass-related specific surface area in the range of between 0.3 m²/g and 0.025 m²/g and in particular less than 0.15 m²/g. Thus, the draw resistance and filtration performance of the inventive filter element can be reduced without reduction in the length of the filter element. Relatively long filter elements enabling a correspondingly long cooling section can thus be realized, which is advantageous relative to the heat balance, particularly when the filter element is used with HNB products.
Additionally thereto, the inventive specification of the mass-related specific surface area of the tow material at a value particularly less than 0.15 m²/g enables the draw resistance and the filtration performance of the filter element to be reduced without reducing the fiber weight in the filter element per volume fraction and/or without reducing the total titer of the tow material. This has the advantage of there being no decrease in the filter element's Filtrona hardness due to a reduction of the fiber weight in the filter element material per volume fraction and/or due to a reduction of the total titer.
The cellulose acetate filaments of the tow material serving as the base product for producing the inventive filter element are in particular cellulose-2,5-acetate, cellulose butyrate, cellulose acetate butyrate, cellulose acetate propionate and/or cellulose propionate filaments. The cellulose acetate filaments preferably have a degree of substitution of about 1.5 to 3.0, preferably about 2.2 to 2.6.
For example, the plasticizers preferably used for the plasticizing of the cellulose acetate fibers and applied to the fibers can be selected from among the following groups: glycerol ester (particularly glycerol triacetate), ethylene and propylene carbonate, citric acid ester (particularly acetyl citrate, triethyl citrate), glycose ester or diethylene glycol dibenzoate.
The person skilled in the art of this technical field is familiar with the amount of plasticizing agent and/or water-soluble bonding agent to be used. In general, there is a plasticizer and/or bonding agent content of about 1 to 14% by weight; in special cases, however, the plasticizer content can easily exceed this range.
Water-soluble bonding agents, as preferentially present on the surface of the cellulose acetate filaments, can in particular be high-boiling solvents applied to the monofilaments of the tow material or to the tow material such as polyalkylene oxides, water-soluble ester or ether, starches, starch derivatives, p-polyvinyl alcohols, polyvinyl ethers, p-polyvinyl acetates and/or polysaccharides, water soluble polyamides and polyacrylates.
Particularly recognized in the present case was that also the residual crimp (RS) of the filter body's tow material and the density (ρ) of the filter body have a significant impact on the performance of the filter element. A residual crimp-related density value A is thereby preferably at least 0.016 mg²/mm⁶with:
$A = ρ^{2} \cdot RS .$
The residual crimp (RS) of the filter body's tow material in particular should thereby not exceed the value of 3.0 and particularly the value of 2.75, whereby the residual crimp (RS) of the tow material is preferably between approximately 1.5 and approximately 2.75 and in particular between 1.9 and 2.5.
The residual crimp is thereby understood as the ratio of the length of the final crimped cellulose acetate filaments to the length of the filter element. Residual crimp is a characteristic feature for a given filter element.
Surprisingly found here was that a relatively low total titer of the filter body tow material at an unchanging acetate weight requires a higher residual crimp value in order to maintain the necessary filter hardness.
A further aspect of the present invention relates to specifying a tow material for producing a filter element for mouthpieces used with smoking products or HNB products, wherein the tow material is optimized to the effect of the filter elements produced from the tow material exhibiting the most consistent possible performance particularly in terms of filtration performance and filter hardness.
In this context, it was determined that thereby also particularly important is for the cellulose acetate filaments of the tow material to exhibit a uniform filament titer which in particular is predefined or definable. This predefined or definable uniform filament titer is particularly within a range of between 5 and 10 denier.
In order to achieve consistent performance of the filter element made from the tow material, particularly with respect to filtration performance and filter hardness, a coefficient of variation of the uniform filament titer should be at most 0.1 and preferably a maximum of 0.05 to a maximum 0.01.
The coefficient of variation of the uniform filament titer, which can also be called the deviation coefficient, is a statistical parameter and characterizes—in contrast to variance—a relative measure of dispersion; i.e. is not dependent on the measurement unit of the statistical variable or random variables.
In other words, ensured during the production of the tow material is that the individual filaments produced by the respectively used spinnerets of the spinning machine exhibit a uniform filament titer.
This can thereby be realized in practice by each spinneret being allotted its own in particular frequency-controlled spin pump in order to ensure that each spinneret of the spinning machine is supplied with the spin fluid (solution of approximately 30% cellulose-2,5-acetate in acetone) in such a way as to enable realizing a uniform nozzle pressure and a uniform amount of spin fluid delivered from each spinneret per unit of time.
This easily realizable yet nevertheless effective approach enables realizing a uniform filament titer which in particular is predefined or definable.
Alternatively or additionally thereto, it is preferential for the monofilaments of the tow material formed from the cellulose acetate filaments to exhibit a uniform total titer, which in particular is predefined or definable, of at least 5000 denier and at most 10,000 denier, wherein a coefficient of variation of the uniform total titer here is preferably at most 0.1 and in particular a maximum of 0.05 to a maximum 0.005. The coefficient of variation is thereby in particular determined by multiple measurements over the length of the tow.
This easily implemented measure can effectively prevent fluctuating quality during manufacture of the inventive filter element, which is unacceptable particularly in the slim and ultra-slim filter market and would thus entail productivity losses during manufacture of the filter elements.
The advantages associated with the invention are thus many. In particular, it is possible to realize slim and ultra-slim filter elements wherein the occurrence of the hot collapse phenomenon is effectively prevented even when the tow material of the filter body has a relatively low total titer and a relatively low filament titer.

Claims

1. A filter element for mouthpieces for use with smoking products or HNB products, wherein the filter element has a filter body made from a tow material, whereby the tow material is formed by a plurality of monofilaments of crosslinked and crimped cellulose acetate filaments, whereby the cellulose acetate filaments exhibit a multilobal or polygonal, optionally Y-shaped, cross-sectional geometry, wherein:

the cellulose acetate filaments of the tow material exhibit a uniform filament titer, which is predefined or definable, in a range of from less than or equal to 10 denier (11.1 dtex) and greater than or equal to 5 denier (5.5 dtex);

the tow material has a total titer in a range of from less than or equal to 10000 denier (11.1 kdtex) and greater than or equal to 5000 denier (5555.5 dtex); and

the specific fiber weight of the cellulose acetate filaments of the tow material is less than or equal to 2.5 mg per mm of filter element length and greater than or equal to 1.0 mg per mm of filter element length.

2. The filter element according to claim 1, wherein a coefficient of variation of the uniform total titer is at most 0.1.

3. The filter element according to claim 1, wherein a coefficient of variation of the uniform filament titer is at most 0.1.

4. The filter element according to claim 1, wherein the filter body is a filter rod with a diameter of between approximately 6 mm and approximately 4 mm, wherein at least part of the filter body is wrapped in a paper or paper-like material.

5. The filter element according to claim 4, wherein the filter body with the paper or paper-like wrapping has a compression depth of less than 0.90 mm when the face end of a cylindrical test piece having a mass of 300 g and a diameter of 12 mm is seated on the filter body perpendicular to the filter body axis.

6. The filter element according to claim 4, wherein the filter body without the paper or paper-like wrapping has a compression depth of less than 0.90 mm when the face end of a cylindrical test piece having a mass of 300 g and a diameter of 12 mm is seated on the filter body perpendicular to the filter body axis.

7. The filter element according to claim 1, wherein at least part of the cellulose acetate filaments of the tow material's monofilaments is at least partially formed as hollow and/or tubular cellulose acetate filaments.

8. The filter element according to claim 1, wherein the filter body hardness amounts to at least 80% Filtrona hardness and preferably at least approximately 86% Filtrona hardness.

9. The filter element according to claim 1, wherein the filter body contains a plasticizer having a plasticizer content of between approximately 2% and approximately 15%, whereby the plasticizer comprises triacetin, triethylene glycol diacetate and/or citric acid ethyl ester.

10. The filter element according to claim 1, wherein the tow material of the filter body exhibits a residual crimp (RS) and a density (ρ), whereby a residual crimp-related density value A amounts to at least 0.016 mg²/mm⁶with:

A=ρ ²·RS.

11. The filter element according to claim 1, wherein the residual crimp (RS) of the filter body's tow material does not exceed the value of 3.0.

12. The filter element according to claim 1, wherein the cellulose acetate filaments of the tow material has a tensile strength of at least 2.6 N/kden.

13. A mouthpiece for use with smoking products or HNB products, wherein the mouthpiece comprises a filter element according to claim 1.

14. The mouthpiece according to claim 13, wherein a capsule-shaped or capsule-like flavor release element is furthermore incorporated into the filter element.

15. A cigarette filter or cigarette filter element comprising a filter element according to claim 1.

16. The cigarette filter or cigarette filter element according to claim 15, wherein a capsule-shaped or capsule-like flavor release element is furthermore incorporated into the filter element.