NL2018776B1

NL2018776B1 - A Filter Tube for a Smoking Article

Info

Publication number: NL2018776B1
Application number: NL2018776A
Authority: NL
Inventors: Meyer Christian
Original assignee: British American Tobacco Investments Ltd
Priority date: 2016-04-29
Filing date: 2017-04-25
Publication date: 2018-01-25
Also published as: CH712424A2; PL126294U1; NL2018776A; HU4954U; BR202017009061U2; GB2549803A; MY172489A; ES1182783U; BE1024591B1; ES1182783Y; CH712424B1; FR3050617A1; CL2017001041U1; GB201607607D0; DE202017102357U1; BE1024591A1; FR3050617B1; CZ30809U1

Abstract

A filtertube for a smoking article is provided. The filtertube can include an empty tube and a filter attached to the empty tube, the empty tube being arranged to accommodate smokeable material inserted by a user. The filter can comprise a first filter section comprising filter material and at least one channel located in an axial region of the filter material, and a second filter section comprising filter material.

Description

Field of the invention

The invention relates to a filter tube for a smoking article. Embodiments of the invention relate to a filter tube for a smoking article having a first section formed from filter material and having at least one channel located in an axial region of the filter material.

Background art “Make-Your-Own” cigarettes are known and are typically formed using a filter tube which the user fills with tobacco, for instance using a hand-held filling device or a larger filling station.

Known smoking article filters, such as cigarette filters, generally comprise a continuous tow of filamentary cellulose acetate. The cellulose acetate is gathered together to form a rod which is cut to form individual filter segments. The smoking article filter may be made of one segment of filter rod, or may be made from multiple segments, with or without a cavity or spaces between them.

Summary of the invention

According to embodiments of the invention, there is provided a filter tube fora smoking article comprising an empty tube and a filter attached to the empty tube, the empty tube being arranged to accommodate smokeable material inserted by a user, wherein the filter comprises a first filter section comprising filter material and at least one channel located in an axial region of the filter material, and a second filter section comprising filter material.

The first filter section can be located at the mouth end of the filter tube, and the second filter section can be located upstream of the first filter section.

The first filter section can comprise a tubular filter section. The tubular filter section can be formed from a fibrous filter material.

The tubular filter section can have an outer circumference of 14mm to 28mm and/or a channel diameter of 1 mm to 6mm.

The second filter section can comprise filter material having a smoke modifying additive disposed in the axial region thereof. The smoke modifying additive can be disposed in a greater concentration in the axial region than in non-axial regions of the filter material of the second filter section. The smoke modifying additive can comprise an encapsulated additive or an additive disposed on a carrier material.

The filter tube can further comprise a third filter section located upstream of the second filter section, the third filter section comprising fibrous filter material and a granular adsorbent material.

The first filter section can have a length between 4 mm and 10 mm and/or the second filter section can have a length of between 10mm and 20mm.

Short description of drawings

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a schematic illustration of a filter tube fora smoking article, the filter tube having a filter with a tubular downstream filter section and an upstream filter section;

Figure 2 is a schematic illustration of a filter tube fora smoking article, the filter tube having a filter with a tubular downstream filter section and an upstream filter section including an encapsulated additive, in the present example a frangible capsule;

Figure 3 is a schematic illustration of a filter tube fora smoking article, the filter tube having a filter with a tubular filter section and a filter section including a thread carrying an additive; and

Figure 4 is a schematic illustration of a filter tube having a filter similar to that described with reference to Figure 2 but also including a further filter section having an adsorbent dispersed in filter material.

Description of embodiments

As used herein, the term “smoking article” includes smokeable products such as cigarettes, cigars and cigarillos whether based on tobacco, tobacco derivatives, expanded tobacco, reconstituted tobacco or tobacco substitutes and also heat-not-burn products and other nicotine delivery devices capable of generating an aerosol for delivery to a consumer. Such smoking articles may be provided with a filter for the gaseous flow drawn by the smoker.

Smoking articles such as cigarettes and their formats are often named according to the cigarette length: “regular (typically in the range 68 - 75 mm, e.g. from about 68 mm to about 72 mm), “short” or “mini” (68 mm or less), “king-size” (typically in the range 75 - 91 mm, e.g. from about 79 mm to about 88 mm), “long” or “super-king” (typically in the range 91-105 mm, e.g. from about 94 mm to about 101 mm) and “ultra-long” (typically in the range from about 110 mm to about 121 mm).

They are also named according to the cigarette circumference: “regular (about 23-26 mm), “wide (greater than 25 mm), “slim (about 22-23 mm), “demi-slim” (about 19-22 mm), “super-slim” (about

16-19 mm), and “micro-slim” (less than about 16 mm). Accordingly, a cigarette in a king-size, super-slim format will, for example, have a length of about 83 mm and a circumference of about 17 mm. Cigarettes in the regular, king-size format are preferred by many customers, namely with a circumference of from 23 to 26 mm and an overall length of from 75 to 91 mm.

Each format may be produced with filters of different lengths, smaller filters being generally used in formats of smaller lengths and circumferences. Typically the filter length will be from 15 mm, associated with short, regular formats, to 30 mm, associated with ultra-long super-slim formats. The tipping paper will have a greater length than the filter, for example from 2 to 10 mm longer.

Filter tubes and filters described hereinafter can be manufactured in any of the above formats. The filter tube can, for instance, be from 70 to 125 mm in length and from 14 to 28 mm in circumference, for producing cigarettes of a similar size.

The terms ‘upstream’ and ‘downstream’ used herein are relative terms defined in relation to the direction of mainstream smoke (or other aerosol) drawn through a smoking article in use. Accordingly, a first element of the filter tube is upstream from a second element if it is further from the mouth end of the filter tube than the second element.

Figure 1 is a schematic illustration of a filter tube 1 for use in forming a smoking article, in the present example a cigarette. The filter tube 1 is generally cylindrical in shape and is in the regular, long format, namely having a length in the range 91 -105 mm and a circumference in the range 23 to 26 mm. In the present example, the filter tube 1 has a diameter of 8.03 mm. The filter tube 1 can have a circumference of 25.13 mm. The filter tube 1 includes an empty tube 3, in the present example formed from paper, and a filter 4. The empty tube 3 and filter 4 are connected together by a tipping paper 5, which wraps around and overlays the filter 4 and a portion of the tube 3. The empty tube 3 is suitable for accommodating smokeable material, such as tobacco, which may be inserted into the tube 3 by the user in order to form a smoking article.

The filter 4 comprises a first section 6 at the mouth end of the filter 4 comprising fibrous filter material 7 formed into a tubular shape and having a channel 8 extending through the centre of the filter material 7. The channel 8 is empty, or hollow. The channel 8 can, for instance, be from 1 mm to 6 mm in diameter, for instance from 2 mm to 5 mm in diameter. The channel 8 extending through the centre of the filter material 7 is, in the present example, an empty, hollow passageway for mainstream smoke or other aerosol drawn through the filter 4. The channel 8, in some embodiments, extends through an axial region of the filter material 7 of the first filter section 6.

The axial region of the first filter section 6 is a region, in the present example, centred on the axis ‘a’ of the filter tube 1, having a radius of about 2.5 mm. In alternative embodiments, the radius of the axial region can be anywhere from 1 mm to 4 mm, or from 1 mm to 3 mm, or about 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm or 3.5 mm.

In the present example, the first filter section 6 is formed from cellulose acetate tow and is not wrapped in a plug wrap, thereby having its fibres exposed on the outer surface of the first filter section 6. Alternatively, the first filter section 6 can be a wrapped filter section, wrapped in a plug wrap. The first filter section 6 can include a plasticiser to achieve a desired rigidity, and in the present example includes about 17% triacetin (glycerin triacetate) by weight of the filter. The plasticiser level can alternatively be any value between 15% and 22% by weight of the filter. The wall thickness of the first filter section around the channel 8 can, for instance, be from 1 mm to 4 mm. However, the specific dimensions may be selected based on the density of filter material forming the first filter section 6 and the level of plasticiser applied to the material, for instance to result in a tube having the desired rigidity, porosity or other characteristics. The tubular first filter section 6 can be manufactured using existing processes and machinery.

The filter 4 further comprises a second filter section 10 upstream of the first filter section 6 comprising filter material 11. The second filter section 10 is wrapped in a plug wrap (not shown), although can alternatively be a non-wrapped filter segment.

The first and second filter sections 6, 10 are held together by a plug wrap 12. The first (downstream) filter section 6 has, in the present example, a length of 7 mm. The second (upstream) filter section 10 has, in the present example, a length of 17 mm.

The first and second filter sections 6, 10 are aligned with the empty tube 3 along the longitudinal axis of the filter tube 1 which is indicated as ‘a’ in Figure 1.

The filter tube 1 is, in the present example, provided with ventilation holes (not shown) through the tipping material 5 and the plug wrap material surrounding the second filter section 10, providing ventilation into the second filter section 10. Ina filter tube with a first (downstream) filter section 6 of length 7 mm and a second (upstream) filter section 10 of length 17 mm, ventilation may be provided at 14 mm, or alternatively 20 mm, from the mouth end, or at a location between 10mm and 25mm from the mouth end.

In use, a consumer inserts smokable material such as tobacco into the paper tube 3 to form a smoking article. The smoking article is then lit by the consumer and tobacco smoke is drawn from the resultant burning coal, through the filter 4. The channel 8 in the first filter section 6 has a lower resistance to mainstream smoke passing through the filter 4 than the surrounding tubular filter material 7, and therefore a greater proportion of mainstream smoke is directed through the channel 8. As an alternative to lighting the smoking article, in alternative smoking articles, the consumer could, for instance, use a heating mechanism to heat, but not combust, the tobacco, or simply draw air through smokable material which is deposited within the tube 3 to release an aerosol.

Figure 2 is a schematic illustration of a filter tube 21 according to a further embodiment of the invention. The features of the filter tube 21 are the same as those of the filter tube 1 described with reference to Figure 1, unless otherwise stated below, and the same reference numerals have been used to identify equivalent components. In this example, the filter 24 includes a second filter section 30 comprising filter material 31 having a capsule 32 disposed therein. The second section 30 is wrapped in a plug wrap (not shown) and is disposed at the upstream end of the filter 24.

The second filter section 30 of Figure 2 is a cellulose acetate segment formed using continuous cellulose acetate fibres and a plasticiser. The capsule 32 is spherical and has a diameter of 3.5 mm, although other shapes and sizes of capsule can be used. The capsule 32 has a rigid outer wall containing a fluid additive which modifies properties of mainstream smoke (or other aerosol) passing from the smokeable material in use. The capsule 32 can be manufactured and inserted into the second filter section 30 using existing processes and machinery. In the present example, the capsule 32 contains menthol flavourant, although other fluids or granular additives could be contained within the capsule 32. The capsule can be ruptured by a consumer to release the fluid additive into the filter material 31.

The axis of the filter tube 21, along which the empty tube 3 and first and second filter sections 6, 30 are aligned, is indicated as ‘a’ in Figure 2. The first (downstream) filter section 6 has, in the present example, a length of 7 mm. The second (upstream) filter section 30 has, in the present example, a length of 17 mm.

In the present example, the capsule 32 is located in an ‘axial region’ of the second filter section 30, in particular such that the centre of the capsule is closer to the axis ‘a’ of the filter tube 21 than to the outer periphery of the filter tube 21. The capsule 32, or other additive material, can be disposed only in the axial region of the filter material of the second filter section 30, or can be disposed in greater concentration in the axial region than in non-axial regions of the filter material of the second filter section 30. The axial region of the second filter section 30 can be a region, in the present example centred on the axis ‘a’ of the filter tube 21, having a radius of about 2.5 mm. In alternative embodiments, the radius of the axial region can be anywhere from 1 mm to 4 mm, or from 1 mm to 3 mm, or about 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm or 3.5 mm.

In the present example, the capsule 32 is located with its centre along the axis ‘a’. In the present example, the capsule 32 is offset from the longitudinal centre of the second filter section 30. In particular, the capsule 32 is located within a portion of the second filter section 30 closer to the downstream end of the second filter section 30. In particular, the distance ‘d’ between the centre of the capsule 32 and the downstream end of the second filter section 30 is less than half of the total longitudinal length of the second filter section 30. In some embodiments, the distance ‘d’ is less than 40%, less than 30% or less than 25% of the total longitudinal length of the second filter section 30. In the present example, the distance ‘d’ is approximately 30% of the total longitudinal length of the section filter section 30. In alternative embodiments, the capsule 32 can be located longitudinally centrally within the second filter section 30 or closer to the upstream end of the second filter section 30 than to the downstream end.

The filter tube 21 is, in the present example, provided with ventilation holes (not shown) through the tipping material 5 and any plug wrap surrounding the second filter section 30, providing ventilation into the second filter section 30. If formed by online laser perforation, the ventilation holes are preferably located in a longitudinal position other than that in which the capsule 32 is located, to avoid damaging the capsule 32 during manufacture. For instance, in a filter tube with a first (downstream) filter section 6 of length 7 mm and a second (upstream) filter section 30 of length 17 mm, ventilation may be provided at 20 mm from the mouth end, while the capsule 32 is longitudinally centrally located within the second filter section and, at 3.5 mm diameter, therefore extends from 13.75 mm to 17.25 mm from the mouth end.

Although only one capsule 32 is used in the illustrated example, two, three or more capsules 32 can alternatively be located within the axial region of the second filter section 30. For instance, for a second filter section 30 having a 17mm length and a first filter section having a 7mm length, a first capsule can be located with its centre at 12mm from the mouth end of the filter 24 and a second capsule can be located with its centre at 18mm from the mouth end of the filter 24. Ventilation perforations could be located at 22mm from the mouth end of the filter 24.

In use, a consumer inserts smokable material such as tobacco into the paper tube 3 to form a smoking article. The smoking article is then lit by the consumer and tobacco smoke is drawn from the resultant burning coal, through the filter24. The channel 8 in the first intersection 6 has a lower resistance to mainstream smoke passing through the filter 4 than the surrounding tubular filter material 7, and therefore a greater proportion of mainstream smoke is directed through the channel 8. As an alternative to lighting the smoking article, in alternative smoking articles, the consumer could, for instance, use a heating mechanism to heat, but not combust, the tobacco, or simply draw air through smokable material which is deposited within the tube 3. The consumer can also break the capsule 32 prior to, during, or after smoking the smoking article, to release the smoke modifying additive contained therein. In the present example, the additive is released in greater concentration into the axial region of the second filter section 30 through which an increased flow of mainstream smoke is directed, as a result of the first filter section 6.

Accordingly, the increased flow of mainstream smoke enhances the delivery of the smoke modifying additive to the consumer and the smoking article can therefore exhibit improved delivery of a smoke modifying additive to a consumer than smoking articles formed from conventional filter tubes.

Since the capsule 32 is located within a portion of the second filter section 30 closer to the first filter section 6, the effect of the increased flow of mainstream smoke on the contents of the capsule 32, once released, is further enhanced. The use of the tubular first filter section 6 at the mouth end of the filter tube 21 enables the capsule 32 to be located closer to the mouth end of the filter tube 21 than would be possible if the second filter section 30 containing the capsule 32 were at the mouth end of the filter tube 21. This is because the tubular first filter section 6 separates the second filter section 30 from the consumer’s mouth, thus preventing the content from the capsule 32 from contacting the consumer’s mouth.

Figure 3 is a schematic illustration of a filter tube 41 having a filter 44 according to a further embodiment of the invention. The features of the filter tube 41 are the same as those of the filter tube 21 described with reference to Figure 2, unless otherwise stated below, and the same reference numerals have been used to identify equivalent components.

The filter tube 41 includes an empty paper tube 3, connected longitudinally to a filter 44 by tipping material 5 overlaying the filter 44 and partially overlaying the paper tube 3. The filter 44 comprises a second section 50 at the upstream end of the filter 44 comprising filter material 51.

In the present case, rather than having a capsule disposed in the second filter section, the filter material 51 has an additive carrying thread 52 disposed therein in an axial region (not shown) of the second section 50, wherein the axial region of the second filter section 50 is as defined in relation to the second filter section 30 of the filter tube 21 described above. The thread can, for instance, be formed from cotton or cellulose acetate fibres and be loaded with between 0.1 and 10 mg of flavourant, such as menthol flavourant. Loading levels of between 0.2 to 2 mg, or between 0.2 and 1 mg of flavourant have been found to be effective. The second section 50 is wrapped in a plug wrap (not shown) although can alternatively be provided as a non-wrapped filter segment. The thread 52 carries an additive capable of modifying mainstream smoke passing through the filter 44, in the present case menthol flavourant.

The filter 44 further comprises a first section 6 at the mouth-end of the filter 44 comprising fibrous filter material 7 formed into a tubular shape and having a channel 8 extending through the centre of the filter material 7, or through an axial region thereof, similar to the first section 6 of the filter 24 of Figure 2 described above.

The second filter section 50 is a cellulose acetate segment formed using continuous cellulose acetate fibres and a plasticiser. The thread 52 can be inserted into the filter material during formation of the second filter section 50 using existing processes and machinery. Although only one thread 52 is used in the present example, two, three or more threads 52 can alternatively be located within the axial region of the second filter section 50.

In use, the smoking article made from the filter tube 41 illustrated in Figure 3 operates in a similar way to a smoking article made from the filter tube 21 illustrated in Figure 2. However, rather than breaking a capsule to release a smoke modifying additive, the consumer can simply smoke the smoking article in the usual manner. When doing so, a greater flow of mainstream smoke is directed, as a result of the first filter section 6, through the axial region of the second filter section 50 in which the thread 52 carrying the smoke modifying additive is located. Accordingly, when the smoking article is smoked, the increased flow of mainstream smoke enhances the delivery of the smoke modifying additive to the consumer and the smoking article can therefore exhibit improved delivery of a smoke modifying additive to a consumer than conventional smoking articles.

Figure 4 is a schematic illustration of a filter tube 61 having a filter 64 according to a further embodiment of the invention. The features of the filter tube 61 are the same as those of the filter tube 21 described with reference to Figure 2, unless otherwise stated below, and the same reference numerals have been used to identify equivalent components. The filter tube 61 includes an empty paper tube 3, connected longitudinally to a filter 64 by tipping material 65 overlaying the filter 64 and partially overlaying the tube 3. The filter 64 comprises three filter sections, including a first filter section 6 as described herein with reference to Figures 1 to 3, a second filter section 30 as described herein with reference to Figure 2, and an additional third filter section 70 at the upstream end of the filter 64 closest to the tube 3.

The third filter section 70 is disposed at the upstream end of the three-part filter 64 and comprises granules of adsorbent material 72, in the present case activated carbon granules, dispersed within a fibrous filter material 71. In the present example, the fibrous filter material 71 is formed from cellulose acetate tow. In the present example, 40 mg of activated carbon granules are used, although other amounts, such as between 10 mg and 80 mg or between 10 mg and 50 mg can be used.

The second filter section 30 has a length of 12 mm in the present example, the first filter section 6 has a length of 7 mm and the third filter section 70 has a length of 10 mm, although other section lengths can be used. Ventilation is provided into the second filter section 30 at a position 17 mm from the mouth end of the filter tube 61. The capsule 32 is located with its centre at 13mm from the mouth end of the filter 64, meaning that it extends from 11,25mm to 14.75mm from the mouth end of the filter 64.

In use, a smoking article formed from the filter tube 61 illustrated in Figure 4 operates in a similar way to a smoking article formed from the filter tube 21 illustrated in Figure 2, with the additional third filter section 70 providing additional selective smoke filtration upstream of the second filter section 30 and therefore without influencing the delivery of smoke modifying additive to the consumer from the capsule 32.

Specific embodiments of the invention have been described, although the invention is not limited to such embodiments. For instance, although the first filter section has been described above as a tubular portion of fibrous filter material, this may take other forms, such as filter material sections with lower density regions extending through an axial region thereof. Also, the tubular section or other section having reduced density in an axial region has been described as being at the mouthend of the filter in some embodiments above, but in any of the embodiments can alternatively be used as a central component or upstream end of multi-part filters, for instance upstream of the section in which the smoke modifying additive is located, while still benefiting from the effect of the invention. In particular, the presence of such a filter section can encourage mainstream smoke to be directed to an axial region of a smoking article both upstream and downstream of the region, due to the lower resistance to draw coinciding with the axial region.

The first, second and (where present) third filter sections described above are discrete segments. Although the first, second and (where present) third filter sections described above are connected together using tipping material, they are individually separate and distinct following their formation and prior to being connected together. The tipping material also connects the filter sections to the respective empty tube 3 of each embodiment. In alternative examples of each of the described embodiments, a plug wrap is used to connect the first, second and (where present) third discrete filter sections before they are connected to the tube 3 using the tipping material. Additional plug wraps may surround one or more of the individual first, second and third filter sections, or may be omitted. The third filter section 70 is described as being added to the first and second filter sections of the filter tube 21 Figure 2, but could also be added upstream of the first and second filter sections of the filter tubes 1,41 of Figures 1 and 3.

In order to address various issues and advance the art, the entirety of this disclosure shows by way of illustration various embodiments in which the claimed invention(s) may be practiced and provide for superior delivery of smoke, aerosol and/or smoke modifying additives. The advantages and features of the disclosure are of a representative sample of embodiments only, and are not exhaustive and/or exclusive. They are presented only to assist in understanding and teach the claimed features. It is to be understood that advantages, embodiments, examples, functions, features, structures, and/or other aspects of the disclosure are not to be considered limitations on the disclosure as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the scope and/or spirit of the disclosure. Various embodiments may suitably comprise, consist of, or consist essentially of, various combinations of the disclosed elements, components, features, parts, steps, means, etc. In addition, the disclosure includes other inventions not presently claimed, but which may be claimed in future.

In view of the above, the present invention can now be summarised by the following embodiments:

Embodiment 1. A filter tube for a smoking article comprising an empty tube and a filter attached to the empty tube, the empty tube being arranged to accommodate smokeable material inserted by a user, wherein the filter comprises:

a first filter section comprising filter material and at least one channel located in an axial region of the filter material, and a second filter section comprising filter material.

Embodiment 2. A filter tube according to Embodiment 1, wherein the first filter section is located at the mouth end of the filter tube, and the second filter section is located upstream of the first filter section.

Embodiment 3. A filter tube according to Embodiment 1 or 2, wherein the first filter section comprises a tubular filter section.

Embodiment 4. A filter tube according to Embodiment 3, wherein the tubular filter section is formed from a fibrous filter material.

Embodiment 5. A filter tube according to Embodiment 4, wherein the tubular filter section has an outer circumference of 14mm to 28mm and a channel diameter of 1 mm to 6mm.

Embodiment 6. A filter tube according to any preceding Embodiment, wherein the second filter section comprises filter material having a smoke modifying additive disposed in the axial region thereof.

Embodiment 7. A filter tube according to Embodiment 6, wherein the smoke modifying additive is disposed in a greater concentration in the axial region than in non-axial regions of the filter material of the second filter section.

Embodiment 8. A filter tube according to Embodiment 6 or 7, wherein the smoke modifying additive comprises an encapsulated additive or an additive disposed on a carrier material.

Embodiment 9. A filter tube according to any preceding Embodiment, further comprising a third filter section located upstream of the second filter section, the third filter section comprising fibrous filter material and a granular adsorbent material.

Embodiment 10. A filter tube according to any one of the preceding Embodiments, wherein the first filter section has a length between 4 mm and 10 mm and/or the second filter section has a length of between 10mm and 20mm.

Claims

CONCLUSIONS

A filter tube for a smoking article comprising an empty tube and a filter attached to the empty tube, wherein the empty tube is adapted to receive smokable material introduced by a user, and wherein the filter is provided with a first filter section comprising filter material and at least one channel located in an axial region of the filter material, and a second filter section comprising filter material.

A filter tube according to claim 1, wherein the first filter section is located at a mouth end of the filter tube, and wherein the second filter section is located upstream of the first filter section.

A filter tube according to claim 1 or 2, wherein the first filter section comprises a tubular filter section.

A filter tube according to claim 3, wherein the tubular filter section is formed from a fiber-like filter material.

A filter tube according to claim 4, wherein the tubular filter section has an outer circumference of 14 mm to 28 mm and a channel diameter of 1 mm to 6 mm.

A filter tube according to any of the preceding claims, wherein the second filter section comprises filter material with a smoke-changing additive disposed in its axial region.

A filter tube according to claim 6, wherein the smoke-changing additive is placed in a greater concentration in the axial region than in non-axial regions of the filter material of the second filter section.

A filter tube according to claim 6 or 7, wherein the smoke-changing additive comprises an encapsulated additive or an additive on a carrier material.

A filter tube as claimed in any preceding claim, further comprising a third filter section disposed upstream of the second filter section, wherein the third filter section comprises fibrous filter material and a granular adsorption material.

A filter tube according to any of the preceding claims, wherein the first filter section has a length between 4 mm and 10 mm and / or wherein the second filter section has a length between 10 mm and 20 mm.

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