FILTER ELEMENT FOR MOUTHPIECES FOR USE WITH SMOKING MATERIALS OR HNB PRODUCTS

Description

[0001] The invention relates to a filter element for mouthpieces for use with tobacco products or HNB products and to the use of such a filter element in mouthpieces for tobacco products or in cigarette filters or in mouthpieces for HNB products.

[0002] Smoking products within the meaning of the present invention relate to classic tobacco products, in particular cigarettes, but also pipes and marijuana products as well as so-called Heat-Not-Burn (HNB) products, vaping products and so-called hybrid products.

[0003] Depending on the application, mouthpieces for smoking products have different functions. On the one hand, mouthpieces can serve as a filter device, for example, to extract harmful components from a stream of tobacco smoke, such as condensed substances, especially tar, as well as particulate matter entrained by the smoke stream. This filter function is particularly useful in traditional tobacco applications. A corresponding mouthpiece can be designed as an integral part of a cigarette or cigarillo, thus forming a "tip" on the cigarette or cigarillo.

[0004] Another type of mouthpiece is a replaceable device, such as a replaceable filter element, which can be removed after use. Such mouthpieces are housed in appropriate holders, such as a cigarette holder or a pipe mouthpiece.

[0005] The cigarette filter is an integral part of a cigarette's mouthpiece. The cigarette filter is designed to reduce the amount of harmful substances such as condensate and gas in the cigarette smoke. Furthermore, the filter makes the smoke somewhat milder or more pleasant for a large percentage of smokers. In a classic filter-tipped cigarette, the filter is wrapped in filter paper and attached to the tobacco rod with a tipping paper. Most industrially manufactured cigarettes are equipped with a filter.

[0006] Numerous types of filter materials are already in use, primarily to reduce the content of tobacco smoke constituents before they reach the smoker's respiratory system. In addition to removing large quantities of harmful components, a satisfactory filter must also be effective without unduly obstructing the passage of air or smoke through the filter, necessitating excessively strong drafts. When using tobacco smoke filters, the filter material must also not alter the taste of the tobacco smoke by imparting its own flavor.

[0007] JPH05276920 A discloses a cigarette filter containing cellulose acetate fibers whose surface area is 0.1 m / g.

[0008] The present invention relates not only to filter materials for the classic tobacco applications described above, but in particular to filter materials or filter elements for mouthpieces for use in smoking articles, wherein these filter elements in particular have functions other than merely a filtering function.

[0009] In other applications, the filtering function of the mouthpiece is by no means the primary focus. This applies, for example, to heat-not-burn products ("HNB products"), which have enjoyed increasing popularity 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, evaporate and are entrained by the air drawn through the HNB product by the user. As the released substances cool, an aerosol forms, which is inhaled by the user.

[0010] Commercially available HNB products typically comprise a device consisting of a power supply that powers a heating element and a separate consumable consisting of a portion of processed tobacco, a support element, such as a tubular cellulose acetate segment, a downstream cooling element, such as a crimped polylactide film gathered into a cylinder with multiple axial channels, and a mouth-side filter. The consumables are inserted into the device prior to use so that the heating element heats the portion of tobacco during use of the HNB product.

[0011] For example, in a so-called IQOS / HEETS product from Philip Morris, the tobacco portion is skewered onto a heating element inside the device. An IQOS / HEETS product is an IQOS device marketed by Philip Morris with the associated HEETS consumable. The HEETS consumable is a heat-not-burn product that simply heats tobacco instead of burning it.

[0012] A competitor product from BAT ("Glo") heats the tobacco externally, replacing the so-called cooling element with a tube. In these devices, a portion of processed tobacco is also heated by a heat source during use, but not burned. Volatile tobacco components, such as flavorings, nicotine, glycerin, and water, vaporize and are entrained by the air drawn through the HNB product by the user. As the released substances cool, an aerosol forms, which is inhaled by the user.

[0013] The consumables known for this application have the disadvantage that their mouth-side filters can heat up considerably due to their proximity to the heating element and the hot steam generated when using the HNB product.

[0014] In so-called hybrid products, an aerosol-forming agent (propylene glycol, glycerin) is first vaporized, and then cooled to form an aerosol. This aerosol is then passed through a portion of processed tobacco and inhaled by the consumer. In such applications, the mouthpiece also serves the primary function of protecting the end facing the user from unpleasant heating.

[0015] In contrast to conventional tobacco products, in which tobacco is burned, it may be desirable for consumables of HNB products that the elements downstream of the heated tobacco portion in the flow direction, such as the cooling element and the mouth-side filter, have only a low filtering effect with regard to condensed components such as tar, since these smoke components can be produced in much smaller quantities.

[0016] The invention is based on the object of providing a filter element for mouthpieces for use with tobacco products or HNB products, wherein the filter element is suitable for a wide range of applications in tobacco products. In particular, a filter element with low draw resistance and low filtration performance is to be provided, which has a sufficiently high Filtrona hardness that is as constant as possible when used in tobacco products, and wherein the filter element can nevertheless be manufactured particularly economically.

[0017] Furthermore, the filter element should in particular exhibit a selective filtration effect on phenols and be suitable for reliably cooling a heated, particle-laden gas so that the temperature of the gas, aerosol or vapor ingested by the user of a smoking article can be reduced.

[0018] These and other objects are solved by the subject matter of independent patent claim 1.

[0019] Accordingly, the invention relates in particular to a filter element for mouthpieces for use with smoking articles or HNB products, wherein the filter element has a filter body made of a tow material, wherein the tow material is formed by a plurality of individual threads of cross-linked and crimped cellulose acetate filaments, and wherein the cellulose acetate filaments have in particular a polygonal and preferably Y-shaped cross-sectional geometry.

[0020] In such a filter element, it was surprisingly found that, in particular while maintaining the total titre of the tow material, a desired reduced filtration performance with respect to condensable components, such as tar, as well as a sufficient filter hardness can be achieved if the tow material has the smallest possible mass-related specific surface area.

[0021] In particular, the tow material of the filter element according to the invention should have a mass-related specific surface area of ​​less than 0.15 m 2 / g and greater than 0.025 m 2 / g. With such a mass-related specific surface area value, which lies between 0.15 m 2 / g and 0.025 m 2 / g, the performance achievable with the filter element and the range of applications can be significantly increased.

[0022] According to preferred embodiments of the filter element according to the invention, the cellulose acetate filter elements of the tow material have, at least in part, a trilobal, i.e., three-armed, star-shaped cross-sectional shape. Such a cross-sectional shape is suitable when the cellulose acetate filaments are to have the largest possible specific surface area in order to enable—if desired, as is the case with classic cigarettes, for example—high filtration capacity while simultaneously using raw materials economically. Alternatively, it is possible to achieve the desired large specific surface area by bundling extremely fine filaments, for example, with a circular cross-section. However, other cross-sectional shapes for the cellulose acetate filaments are also conceivable, such as a polygonal or quadrangular cross-sectional shape.

[0023] The tow material of the filter element according to the invention is formed from continuous stuffer-box-crimped cellulose acetate filaments. A solution of approximately 30% cellulose 2,5-acetate in acetone is forced through spinnerets, the acetone is evaporated in a spinning shaft, a plurality of cellulose acetate filaments are gathered into a ribbon, and this ribbon is then stuffer-box-crimped. The product is then dried and typically pressed into bales. The tow material ("filter tow") is removed from the bale and processed into filter rods on a filter rod machine. The tow material is stretched in a stretching device, provided with an additive for bonding the cellulose acetate filaments, compacted transversely and axially after forming a so-called sliver, optionally wrapped with paper, and cut to the final length of the filter element.

[0024] By selecting a mass-related specific surface area for the tow material of the filter element, in particular in a range of less than 0.15 m 2 < / g and greater than 0.025 m 2 < / g, according to the invention, a filter element can be realized which achieves a desired reduced filtration performance with respect to condensable components but nevertheless a sufficient filter hardness while maintaining the total titre.

[0025] According to embodiments of the filter element according to the invention, the cellulose acetate filaments of the individual threads of the tow material are formed at least in regions as hollow and / or tubular cellulose acetate filaments.

[0026] Hollow or tubular cellulose acetate filaments are to be understood as meaning, in particular, preferably cylindrical filaments which, when viewed in cross section, have one or more continuous cavities.

[0027] Such hollow fibers can be designed, at least partially, as multi-lumen hollow fibers. Compared to "solid" cellulose acetate filaments, single- or multi-lumen tubular cellulose acetate filaments are significantly more kink-resistant, allowing particularly high Filtrona hardnesses to be achieved without increased material densification.

[0028] According to embodiments of the present invention, the hollow cellulose acetate filaments have at least partially a trilobal, i.e., three-armed star-shaped cross-sectional shape. Such a cross-sectional shape is suitable when the cellulose acetate filaments are to have the largest possible specific surface area, for example, to enable high filtration capacity while simultaneously using raw materials economically.

[0029] Alternatively, it is possible to achieve the desired large specific surface area by using a bundle of extremely fine filaments with a circular cross-section. However, other cross-sectional shapes for the hollow cellulose acetate filaments are also conceivable, such as a square cross-section.

[0030] Because the filter element according to the invention has a filter body which can be based at least partially on cellulose acetate filaments which are at least partially formed as hollow cellulose acetate filaments, a low tensile resistance and a low filtration performance can be realized, since the filaments of the filter element which are at least partially formed as hollow cellulose acetate filaments have a small outer surface relative to the total fiber volume.

[0031] In this context, it was surprisingly found that particularly high Filtrona hardnesses can be achieved with the filter element due to the filaments being at least partially formed as hollow cellulose acetate filaments.

[0032] In fact, it has been found that filter elements that 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 volume.

[0033] Since the filter element according to the invention is based on cellulose acetate filaments, the filter element according to the invention is designed to form a uniform, white and flat mouth-side end face for a tobacco rod, for example a cigarette, wherein a selective filtration effect on phenols can also be realized.

[0034] By using a filter element based on cellulose acetate filaments, filter rods can be produced, particularly for cigarettes, which, with regard to the discussion on smoking and health, have proven to have outstanding properties regarding specific retention phenomena.

[0035] For example, a cellulose acetate filter filters harmful nitrosamines and phenols far more effectively than condensate and nicotine. Furthermore, smokers find the smoky taste of today's common tobacco blends, such as "American Blend," "German Blend," and "Virginia," most pleasant when combined with a cellulose acetate filter rod. Another not to be underestimated advantage of a cellulose acetate filter rod is the optical homogeneity of the filter's cut surfaces.

[0036] Since, according to embodiments, the filter element according to the invention is formed at least partially from hollow cellulose acetate filaments which serve as filling material, the tensile resistance and the filtration performance of filter rods made from the material according to the invention can be varied over a wide range.

[0037] In particular, it has been shown that a filter material consisting, at least in part, of hollow cellulose acetate filaments exhibits an improved thermal cooling effect. It was found that the use of hollow cellulose acetate filaments as filler material still allows a very low filtering efficiency, i.e., retention efficiency, for the suspended solids and gases to be removed.

[0038] It is assumed that this effect is achieved by the hollow cellulose acetate filaments altering the surface or flow of the gas or air to be purified in such a way that any suspended particles present in the gas or air are barely retained. Another reason could be that the use of hollow cellulose acetate filaments allows for a different, particularly advantageous surface structure of the filter material.

[0039] The filter element according to the invention further has the advantage that it enables, in particular, adjustable cooling of a heated, particle-laden gas (in particular an aerosol), so that the temperature of the gas, aerosol, or vapor ingested by the user of a smoking article or HNB product can be specifically reduced. By varying the proportion of hollow cellulose acetate filaments in the filter and / or filler material, the desired cooling effect can be adapted to the specific application.

[0040] It is also important to note that the hollow cellulose acetate filaments (= hollow fibers) in the filter element according to the invention are essentially flowed around rather than through. Geometric considerations show that the fiber-to-fiber distances are significantly larger than the lumen (hollow portion) of the hollow fiber. The viscosity of the aerosol (essentially air) then ensures that the path of least resistance is chosen (i.e., it flows between the filaments rather than through each individual filament).

[0041] In other words, in the embodiment of the filter element according to the invention, the effective filtration surface is by no means maximized, since the hollow cellulose acetate filaments in the tow material are not flowed through.

[0042] In particular, the hollow cellulose acetate filaments can thus have kinks that close the lumen of the hollow cellulose acetate filaments without this having an influence on the performance of the filter and / or filling material according to the invention with regard to the set target parameters.

[0043] It is particularly important to note in this context that the hollow-shaped cellulose acetate filaments designed as hollow fibers do not necessarily have to be completely hollow, but can also be partially closed by kinks. They can also deviate from an ideal circular shape.

[0044] In embodiments of the invention, the hollow cellulose acetate filaments of the tow material serve both as a carrier material and as a cooling material. By simultaneously serving as a carrier material, the hollow cellulose acetate filaments allow for particularly compact filter elements that do not require an increase in the dimensions of the smoking article.

[0045] The term "Filtrona hardness" used herein refers to the filter hardness determined according to the Filtrona principle. According to this principle, filter hardness is determined by pressing a 12 mm diameter cylindrical rod with its flat end vertically onto a horizontally positioned filter rod with a load of 300 g. The ratio of the compressed diameter to the initial diameter previously determined by the first contact yields the percentage of Filtrona hardness.

[0046] The hardness of the filter element or filter rod is an important target criterion, especially for cigarette filters. It is usually specified as the so-called Filtrona hardness. It should be noted that the Filtrona hardness is only measured on a filter element, not on the underlying filter (raw) material, i.e., the tow material. The Filtrona hardness of a filter element is influenced in particular by the amount of triacetin that is / can be sprayed onto the filter element.

[0047] The minimum Filtrona hardness limit is approximately 88% and is based on market requirements. The Filtrona hardness of the filter element can preferably be set to approximately 88% to 95%, in particular approximately 90% to 93%.

[0048] According to preferred embodiments of the filter element according to the invention, it is provided that the filter body is designed in particular as a filter rod and preferably has a diameter between approximately 8 mm and approximately 5 mm and in particular a diameter of approximately 7.8 mm or approximately 5.35 mm, wherein the filter body is at least partially covered with a paper material or a paper-like material.

[0049] In this design, the Filtrona hardness of the filter element should preferably be greater than 85% and in particular greater than 90%.

[0050] For a given filter element diameter, the Filtrona hardness is determined in particular by the fiber weight per volume, whereby the filament titer of the cellulose acetate filaments of the tow material has only a minor influence on the Filtrona hardness.

[0051] In embodiments of the filter element according to the invention, it is provided that the filter body has a fiber weight which is a maximum of 10 mg / mm filter element length.

[0052] The Filtrona hardness of the filter element can also be achieved by using a stronger filter wrapping paper or a stronger tipping paper.

[0053] Tipping paper is a paper used to either connect multiple filter elements together or to connect a filter element to a tobacco rod. However, increasing the Filtrona hardness of the filter element by using a thicker filter wrapping paper or a thicker tipping paper has economic disadvantages, as this approach is expected to result in higher costs.

[0054] Associated with the Filtrona hardness of the filter element is the so-called "hot collapse," whereby the filter hardness decreases during use of the filter element, i.e., during use with tobacco products or HNB products. This phenomenon can occur particularly when the filter element is heated in the presence of moisture during one of the last puffs of a traditional cigarette. However, this undesirable effect can also occur with HNB products.

[0055] In this context, it has been shown that the degree of decrease in Filtrona hardness due to the "hot collapse" phenomenon can be significantly reduced if a tow material with the said mass-related specific surface area of ​​less than 0.15 m 2 / g is used as the starting material of the filter element according to the invention.

[0056] By ensuring that the tow material of the filter body of the filter element according to the invention has a mass-related specific surface area in the range between 0.3 m 2 / g and 0.025 m 2 / g, and in particular less than 0.15 m 2 / g, the draw resistance and filtration performance of the filter element according to the invention can be reduced without reducing the length of the filter element. Thus, relatively long filter elements can be realized, allowing a correspondingly long cooling section, which is advantageous for heat management, especially when using the filter element with HNB products.

[0057] In addition, by setting the mass-related specific surface area of ​​the tow material to a value of, in particular, less than 0.15 m 2 / g, the inventive method allows the draw resistance and 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 that no decrease in the Filtrona hardness of the filter element occurs due to a reduction in the fiber weight in the filter element material per volume fraction and / or due to a reduction in the total titer.

[0058] According to embodiments of the filter element according to the invention, the filter body has a fiber weight of max. 10 mg / mm filter element length. In particular, the tow material, which forms the starting product for the production of the filter element according to the invention, should have a total titer of 10,000 denier to 40,000 denier.

[0059] The cellulose acetate filaments of the tow material serving as the starting material for producing the filter element according to the invention are, in particular, cellulose 2,5-acetate, cellulose butyrate, cellulose acetobutyrate, cellulose acetopropionate, and / or cellulose propionate filaments. The cellulose acetate filaments preferably have a degree of substitution of approximately 1.5 to 3.0, more preferably approximately 2.2 to 2.6.

[0060] The plasticizers preferably used for plasticizing and in particular thermoplasticizing the cellulose acetate fibers and applied to the fibers can, for example, be selected from the following groups: glycerol esters (in particular glycerol triacetate), ethylene and propylene carbonate, citric acid esters (in particular acetyl and triethyl citrate), glucose esters or diethylene glycol dibenzoate.

[0061] The amount of plasticizing plasticizer and / or water-soluble adhesive to be used is familiar to those skilled in the art. Generally, the plasticizer and / or adhesive content is approximately 1 to 14 percent by weight; however, in special cases, the plasticizer content can easily exceed this range.

[0062] As water-soluble adhesives, which are preferably present on the surface of the cellulose acetate filaments, there can be used in particular high-boiling solvents, such as polyalkylene oxide, water-soluble esters or ethers, starch, starch derivatives, P-polyvinyl alcohols, polyvinyl ethers, P-polyvinyl acetates and / or polysaccharides, water-soluble polyamides and polyacrylates, which are applied to the individual threads of the tow material or to the tow material.

[0063] In particular, it was recognized that the residual crimp (RS) of the tow material of the filter body and the density ( r ) of the filter body has a decisive influence on the performance of the filter element. According to the invention, a residual crimp-related density value A is at least 0.016 mg 2< × mm 6< with: A = ρ 2 ∗ RS .

[0064] In particular, the residual crimp (RS) of the tow material of the filter body should not exceed the value of 1.7 and in particular the value of 1.45, wherein the residual crimp (RS) of the tow material is preferably between about 1.05 and about 1.4 and in particular between 1.1 and 1.3.

[0065] The residual crimp is defined as the ratio of the length of the uncrimped cellulose acetate filaments to the filter element length. The residual crimp is a characteristic feature of a given filter element.

[0066] According to a further aspect of the present invention, it is important to provide a tow material for producing a filter element for mouthpieces for use with smoking articles or HNB products, wherein the tow material is optimized such that the filter elements produced from the tow material have the most uniform performance possible, in particular with regard to filtration performance and filter hardness.

[0067] In this context, it was determined that it is particularly important that the cellulose acetate filaments of the tow material have a uniform filament count, which is particularly predetermined or can be determined. This uniform filament count, which is particularly predetermined or can be determined, is in a range between 8 denier and 30 denier, preferably between 9 denier and 30 denier, and even more preferably between 10 denier and 20 denier.

[0068] In order to achieve a uniform performance of the filter element made of the tow material, especially with regard to filtration performance and filter hardness, a variation coefficient of the uniform filament titre should be a maximum of 0.1 and preferably a maximum of 0.05 to a maximum of 0.01.

[0069] The coefficient of variation of the uniform filament titer, which can also be referred to as the deviation coefficient, is a statistical parameter and describes - in contrast to the variance - a relative measure of dispersion, i.e. it does not depend on the unit of measurement of the statistical variable or random variable.

[0070] In other words, during the production of the tow material, care is taken to ensure that the individual filaments produced by the respective spinnerets of the spinning machine used have a uniform filament titre.

[0071] In practice, this can be achieved by assigning each spinneret its own spinning pump, in particular a frequency-controlled spinning pump, to ensure that the spinning liquid (solution of approximately 30% cellulose-2,5-acetate in acetone) is supplied to each spinneret of the spinning machine in such a way that a uniform nozzle pressure and a uniform amount of spinning liquid delivered per unit of time by each spinneret can be achieved.

[0072] With this simple to implement but nevertheless effective method, it is possible to realize a uniform filament titer, particularly one that is predetermined or can be determined.

[0073] Alternatively or additionally, it is preferred that the individual threads of the tow material formed from the cellulose acetate filaments have a predetermined or definable and preferably uniform thread titer of at least 200 denier and a maximum of 4,000 denier and preferably of at least 250 denier and a maximum of 2,500 denier, wherein a variation coefficient of the uniform thread titer is preferably at most 0.1 and in particular at most 0.05 to a maximum of 0.01.

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 individual filaments of cross-linked and crimped cellulose acetate filaments, whereby the cellulose acetate filaments in particular exhibit a polygonal and preferably Y-shaped cross-sectional geometry, and whereby the tow material has a mass-related specific surface area of less than 0.15 m2 / g and more than 0.025 m2 / g, and 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 × mm6, with: A = ρ 2 ∗ RS .

2. The filter element according to claim 1, wherein the residual crimp (RS) of the tow material of the filter body does not exceed the value of 1.7, whereby the residual crimp (RS) of the tow material of the filter body is preferably between approximately 1.1 and approximately 1.7 and in particular between 1.3 and 1.7.

3. The filter element according to claim 1 or 2, wherein the filter body exhibits a fiber weight, whereby the fiber weight of the filter body amounts to a maximum 10 mg / mm filter length.

4. The filter element according to one of claims 1 to 3, wherein the cellulose acetate filaments of the tow material exhibit an in particular predefined or definable uniform filament titer, particularly a predefined or definable uniform filament titer within a range of between 8 denier (8.88 dtex) and 30 denier (33.33 dtex), and preferably between 9 denier (10 dtex) and 30 denier (33.33 dtex), and more preferably between 10 denier (11.11 dtex) and 20 denier (22.22 dtex).

5. The filter element according to claim 4, wherein a coefficient of variation of the uniform filament titer is at most 0.1 and preferably 0.05 maximum to 0.01 maximum.

6. The filter element according to one of claims 1 to 5, wherein the individual filaments of the tow material formed from the cellulose acetate filaments comprise an in particular predefined or definable and preferably uniform filament titer of at least 200 denier (222 dtex) and at most 4000 denier (4.444 dtex) and preferably at least 250 denier (277 dtex) and at most 2500 denier (2.777 dtex).

7. The filter element according to claim 6, wherein a coefficient of variation of the uniform filament titer is at most 0.1 and preferably 0.05 maximum to 0.01 maximum.

8. The filter element according to one of claims 1 to 7, wherein the filter body is in particular realized as a filter rod and preferably with a diameter of between approximately 8 mm and approximately 5 mm and particularly a diameter of approximately 7.8 mm or approximately 5.35 mm, whereby at least part of the filter body is wrapped in a paper or paper-like material.

9. The filter element according to claim 8, wherein the filter body with the wrapping composed of paper or paper-like material has a compression depth of less than 0.90 mm and in particular less than 0.85 mm when a cylindrical test piece having a mass of 300 g and a diameter of 12 mm is placed at the front end of the filter body perpendicular to the filter body axis.

10. The filter element according to claim 8, wherein the filter body without the wrapping composed of paper or paper-like material has a compression depth of less than 0.90 mm and in particular less than 0.85 mm when a cylindrical test piece having a mass of 300 g and a diameter of 12 mm is placed at the front end of the filter body perpendicular to the filter body axis.

11. The filter element according to one of claims 1 to 10, wherein the cellulose acetate filaments of the individual filaments of the tow material are at least partially formed as hollow and / or tubular cellulose acetate filaments.

12. The filter element according to one of claims 1 to 11, wherein the hardness of the filter body is at least 80% Filtrona hardness and preferably at least 90% Filtrona hardness.

13. The filter element according to one of claims 1 to 12, wherein the filter body has a plasticizer exhibiting a plasticizer content between approximately 2% and approximately 15% and preferably between approximately 4% and 10%, whereby the plasticizer in particular comprises triacetin, triethylene glycol diacetate and / or citric acid diethyl ester.

14. The filter element according to one of claims 1 to 13, wherein the tow material exhibits a total titer of between 4000 denier (4.444 dtex) and 40000 denier (44.444 dtex) and preferably between 6000 denier (6.667 dtex) and 30000 denier (33.333 dtex).