WO2011000639A1

WO2011000639A1 - A filter for a smoking article

Info

Publication number: WO2011000639A1
Application number: PCT/EP2010/057321
Authority: WO
Inventors: John Richardson; Peter Rex White
Original assignee: British American Tobacco (Investments) Limited
Priority date: 2009-06-29
Filing date: 2010-05-27
Publication date: 2011-01-06
Also published as: GB0911181D0

Abstract

A filter for a smoking article comprising a filter section and a recess section longitudinally aligned with and adjacent to the filter section, the filter section comprising a plug of filtration material and a thread extending through the plug of filtration material to an end face of the filter section, wherein the recess section is defined at a mouth end of the filter and extends from said end face of the filter section. Also provided is a smoking article comprising a filter according to the invention.

Description

A filter fof a smoking article Description The present invention relates to a filter for a smoking article.

As used herein, the term 'smoking article' includes smokeable products such as cigarettes, cigars and cigarellos, whether based on tobacco, tobacco derivatives, expanded tobacco, reconstituted tobacco or tobacco substitutes and also heat-not- burn products, but is not limited thereto.

A cigarette typically includes a tobacco rod and a filter connected to the tobacco rod. The filter is commonly made of cellulose acetate tow. A smoker ignites one end of the tobacco rod and draws smoke in through the filter. The filter traps some of the smoke constituents produced by the burning tobacco rod.

It is well known that filtration of smoke in a smoking article, such as a cigarette may affect the taste and flavour characteristics of a product when smoked. However, in some cases, the filter can be arranged to impart additional characteristics to the cigarette such as a flavourant to improve the flavour of smoke received by a user.

It is known to provide a filter with at least one flavoured element extending along the central axis of a cigarette filter during the filter manufacturing process. The preferred flavoured element is cotton yarn, but other suggested materials for the flavoured element are cellulose acetate, rayon, or some other textile or non-textile materials capable of absorbing a liquid flavourant. In such a filter, a thread or tape, for example, cotton thread or cellulose acetate, extends along a filter rod and a flavourant is incorporated into the thread or tape. Although a thread extending along a filter absorbs flavour during manufacturing and then imparts flavour during smoking, it does have certain disadvantages as a flavourant. For example, a user may contact the end of the filter during

consumption of the smoking article which may lead to discolouration of the user's mouth and tongue due to direct contact of the thread thereon and intense flavours may be imparted by the flavourant being directly in contact with the tongue as opposed to being dispersed in the smoke. Therefore, the present invention seeks to provide a filter for a smoking article which overcomes or substantially alleviates the problems associated with

conventional filters for smoking articles described above.

According to the present invention, there is provided a filter for a smoking article comprising a filter section and a recess section longitudinally aligned with and adjacent to the filter section, the filter section comprising a plug of filtration material and a thread extending through the plug of filtration material to an end face of the filter section, wherein the recess section is defined at a mouth end of the filter and extends from said end face of the filter section.

Preferably, the recess section is open at the mouth end of the filter.

Conveniently, the thread extends through the filter between opposing end faces of the plug of filtration material.

Advantageously, the thread extends parallel to a longitudinal axis of the filter.

Preferably, the thread extends through an inner portion of, and is surrounded by, the filtration material.

The plugwrap may extend circumferentially around the filter section and may extend longitudinally from said end face thereof to form the recess section.

In a preferred embodiment, the filter section is a first filter section and the filter further comprises a second filter section.

Advantageously, the second filter section is longitudinally aligned with and adjacent to the first filter section. In a preferred embodiment, the first filter section is disposed between the second filter section and the recess section. The second filter portion may comprise a longitudinally extending plug and a particulate material disposed in a circumferential region of the plug.

Conveniently, the particulate material extends to an end of the second filter portion immediately adjacent the first filter portion.

Preferably, two or more portions of the circumferential region of the second section comprise particulate material spaced circumferentially from one another.

Advantageously, the particulate material extends over a full longitudinal length of the second section.

A wrapper may be engaged around the plug, and the particulate material may be adhered to the surface of the wrapper. Preferably, the plug further comprises a particulate material interspersed in the filtration material and the particulate material is adsorbent.

In a preferred embodiment, the particulate material is activated carbon. The thread may contain a flavourant and/or a colourant.

According to another aspect of the invention, there is provided a smoking article including a filter for a smoking article comprising a filter section and a recess section longitudinally aligned with and adjacent to the filter section, the filter section comprising a plug of filtration material and a thread extending through the plug of filtration material to an end face of the filter section, wherein the recess section is defined at a mouth end of the filter and extends from said end face of the filter section. - A -

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: FIGURE 1 illustrates a perspective view of a smoking article including a rod of smokeable material and a filter according to the present invention;

FIGURE 2 illustrates a filter element for a smoking article according to a first embodiment of the invention;

FIGURE 3 illustrates a filter element for a smoking article according to a second embodiment of the invention; and

FIGURE 4 illustrates a surface of a wrapper having the particulate material applied thereto.

Referring now to the drawings, there is shown in Figure 1 a smoking article 1 in the form of a cigarette, which includes a filter 2 in accordance with one aspect of the present invention. Even though Figure 1 shows the smoking article as a cigarette, it should be appreciated that the smoking article 1 may take other forms, such as a cigar or cigarillo etc., which may also include the filter 2 according to the invention. Referring to Figure 1, the smoking article 1 comprises a generally cylindrical paper- wrapped rod 3 of smokeable material, such as tobacco, co-axially attached to the filter 2 by a tipping paper 4, which is glued around one end of the rod 3 of smokeable material and the filter 2 in a conventional manner, and so no further discussion of the tipping paper 4 will be given herein.

A first embodiment of the filter 2 attached to the rod of smokeable material 3 is shown in Figure 2. In this embodiment, the filter 2 comprises a single filter section 5 about 22mm in length, which includes a continuous plug of filtration material 6 typically having a diameter of 7.5mm to 8mm which is circumscribed by a plugwrap 7. The plugwrap 7 is longer than the plug of filtration material 6 and overhangs the plug of filtration material 6 at a mouth end 8 of the filter 2 to create a recess section 9 having a depth of approximately 5mm. The length of the overhang of the plugwrap 7 and hence the depth of the recess 9 is designated in Figure 2 by the reference character 'x'.

The plugwrap 7 is a wrapper having a high base weight, for example 100g/m² to provide rigidity to the recess section 9. The plugwrap 7 forming the recess section 9 at the mouth end 8 of the smoking article is made of heavyweight plugwrap to ensure that the recess is maintained and does not easily collapse due to the absence of any supporting filter material. In this embodiment the plug of filtration material 6 is fibrous cellulose acetate, although it will be understood that any conventional filtration material may be used. The filter element 5 has first and second circular end faces 12,13. As shown in Figure 2, a thin thread 15 extends between the two end faces 12,13. The thread extends parallel with a longitudinally extending outer face 14 of the plug of filtration material 6 and extends through the centre of the plug of filtration material 6. The thread 15 typically has a diameter between 0.3mm and 0.8mm, although the diameter is not limited thereto. The thread 15 is formed from cellulose acetate, although it will be appreciated that alternative materials may be used. The thread 15 may be flavoured and/or coloured and may be arranged in a variety of configurations within the filter, although the invention is not limited as such and various other configurations are possible within the scope of the invention.

The filter is arranged with the recess section 9 disposed at the mouth end 8 of the smoking article 1, which is extends from the first end face 12 of the filter section 5. The recess section 9 is defined by a circumferentially extending inner surface of the plugwrap 7 extending from the filter section 5 together with the first end face 12 of the filter section 5. The recess section 9 also has an opening 16 at the mouth end 8. An advantage of the above arrangement is that the first end face 12 of the filter is visible during use, so that a user can see an end of the thread 15 on the first end face 12. However, it is not possible for the user to come into contact with the thread 15 on the first end face 12 due to the recess section 9 spacing the first end face 12 from the mouth end 8. The second end face 13 of the filter section 5 abuts the rod of smokeable material 3.

In use, a user inserts the mouth end 8 of the smoking article into their mouth and lights the paper-wrapped rod 3 of smokeable material at the distal end of the smoking article to the mouth end 8 such that said end burns. The filter 2 is located at the mouth end 8 of the smoking article 1 such that a gaseous flow, comprising smoke drawn from the rod 3 of smokeable material, moves through the filter 2 before entering the mouth of the user. The thread 15 is disposed in the filter element 5, and extends longitudinally between the end faces 12,13 of the plug of filtration material, as described above. In this way, the thread 15 is disposed in close proximity with the path of the gaseous flow as it moves through the filter 4, and is therefore able to affect various characteristics on the gaseous flow before said flow reaches the smoker's mouth.

It is known for users to bite and/ or chew the filter 2 at the mouth end 8 of the smoking article 1. Therefore, the recess 9 limits the user from chewing and/orbiting the filter element 5. Furthermore, the recess 9 distances the thread from the mouth end 8 of the filter and so avoids unnecessary contact of the thread 15 as well as the filtration material by the user which prevent colouration and any associated flavourings due to direct contact of the user's mouth or tongue on the thread.

However, an end of the thread 15 at the first end face 12 remains visible to the user.

The recess portion 9 at the mouth end 8 is also advantageous in that it provides additional space in which the flavour obtained from the thread 15 mixes with the smoke in the gaseous flow, so that a consistent flavour is obtained. Additionally, the recess allows the gaseous flow to cool before entering the user's mouth.

The thread 15 may, for example, affect the overall properties of the gaseous flow such that the taste and flavour of the gaseous flow are improved. One application of the thread 15 is to replace a degree of the taste and flavour characteristics of the gaseous flow which may be lost as the gaseous flow moves through the filtration material. The thread extending longitudinally through the plug of filtration material itnproves the flavour of the smoke without compromising the flow characteristics of the smoke.

Although in this embodiment only a single thread is shown, it will be understood that in an alternative embodiment a plurality of threads may be formed in the filtration material.

A second embodiment of a filter attached to a rod of smokeable material is shown in Figure 3. The features and components of the second embodiment of the filter described below are generally the same as for the filter described above in accordance with a first embodiment, and so components and features that are generally the same retain the same reference numerals. However, in this

embodiment the filter 20 comprises first and second filter sections 21,22. The first filter section 21 of this exemplary embodiment is generally the same as the filter section 5 of the first embodiment described above, and so an in depth discussion will be omitted herein. The first filter section 21 includes the continuous plug of filtration material 6 which is circumscribed by the plugwrap 7. The plugwrap 7 is longer than the plug of filtration material 6 and overhangs the plug of filtration material 6 at the mouth end 8 of the filter 20 to create the recess section 9.

In this second embodiment of the filter 20, the second filter section 22 is disposed between the first filter section 21 and the rod of smokeable material 3 when the filter 2 is disposed in the smoking article 1, such that the first filter section 21 is longitudinally aligned with and disposed between the recess section 9 and the second filter section 22. Therefore, the first filter section 21 is closer to the mouth end 8 of the filter 20 than the second filter section 22 and separates the second filter section 22 from the recess section 9. The second filter section 22 comprises a central plug 23 of filtration material, such as fibrous cellulose acetate, and a particulate material 24, such as carbon or activated carbon interspersed in said filtration material. The particulate material 24 in the central plug 23 is optional (although in some embodiments is preferred). The second filter section 22 further comprises a wrapper 25, preferably a plugwrap material, having a particulate material 26 such as carbon or activated carbon adhered on an inner surface thereof. The wrapper 25 circumferentially envelopes the central plug 23 about the longitudinal axis extending through the filter 20, and has a lapped and seamed region. Alternatively, the wrapper 25 is a split wrapper bonded to the plug 23. The second filter portion 22 has first and second circular end faces 28,29.

The surface of the wrapper 25 having particulate material 26 adhered thereto is shown in Figure 4. The particulate material 26 is disposed in separate regions 27 spaced from each other on the inner surface of the wrapper 25. Each of the separate regions 27 of particulate material 26 extend longitudinally along the wrapper 27, however the particulate material 26 extends only partially across the width of the wrapper 25 and longitudinal edges 30 are free from particulate, thus providing a lapped and stuck seam free from particulate when formed around the central plug 23. When the wrapper 25 is formed around the plug 23 by conventional means, the particulate material 26 is disposed in two separate regions spaced diametrically opposite each other. It will be understood that the number of separate regions 27 of particulate material 26 disposed on the wrapper 25 is not limited to two regions, and that other arrangements of particulate material 26 may be used. For example, three, four, five or six separate regions spaced from each other on the inner surface of the wrapper 25 may be used. In such arrangements, the regions are evenly and symmetrically positioned around the longitudinal axis extending through the second filter section 22. However, other spacings may be used. Further, the regions on a particular wrapper may or may not be all of equal width, and may or may not be of equal width with the gaps between the regions. Similarly, the gaps between the regions may not be of equal width.

An advantage of the symmetrical arrangement is that it obviates bending or curving of the filter element that can arise in a non-symmetric arrangement if the adhered particulate material pulls on and distorts the wrapper and hence the filter. The particulate material 26 disposed on the wrapper 25 is selected from a group of relatively high surface area of materials capable of adsorbing smoke constituents without a high degree of specificity, although the particulate material is not limited thereto. Suitable general adsorbents can be selected from the group consisting of carbon, activated carbon, activated charcoal, activated coconut carbon, activated coal-based carbon or charcoal, zeolite, silica gel, meerschaum, aluminium oxide (activated or not), carbonaceous resin or combinations thereof. The particulate mixture used may be a single substance or a mixture, and/or may be in a mixture with another material.

The filter 20 is arranged with the recess section 9 disposed at the mouth end 8 of the smoking article 1, which extends from the first end 12 of the first filter section 5. The recess section 9 is defined by the circumferentially extending inner surface of the plugwrap 7 extending from the first filter section 21 and the first end 12 of the first filter section 21, and has the opening 16 at the mouth end 9. The first end 12 of the first filter section 21 is visible to a user through the opening 16.

The second end 13 of the first filter section 21 abuts the first end 28 of the second filter section 22, such that the opening 16 of the recess 9 and the second end 29 of the second filter section 22 define the opposing ends of the filter 20.

An advantage of the above arrangement is that the provision of the particulate material 26 disposed in a circumferential region of the second filter section 22 increases the effectiveness of the filter 20 at filtering the gaseous flow therethrough. Therefore, the filter 20 may be shortened without negating the effectiveness of the filter section 20 at filtering the gaseous flow therethrough and so there is provision to provide the recess section 9 without lengthening the filter 20 compared to conventional filters.

The provision of the first filter section 21 between the recess section 9 and the second filter section 22 allows the second filter section 22 to be upstream of the filtration material of the first filter section 21 and prevents the particulate material 26 disposed in a circumferential region of the second filter section 22 from being dislodged or displaced therefrom and entering the recess section 9. Such loose particulate material 26 could then come into contact with a user. Furthermore, with the above arrangement the particulate material 26 disposed in a circumferential region of the second filter section 22 and particulate material 26 interspersed in the filtration material of the plug 23 of the second filter section 22 is not visible to the user.

Although embodiments of the invention have been shown and described, it will be appreciated by those skilled in the art that variations may be made to the above exemplary embodiments that lie within the scope of the invention, as defined in the following claims.

Claims

1. A filter for a smoking article comprising a filter section and, a recess section longitudinally aligned with and adjacent to the filter section, the filter section comprising a plug of filtration material and a thread extending through the plug of filtration material to an end face of the filter section, wherein the recess section is defined at a mouth end of the filter and extends from said end face of the filter section.

2. A filter according to claim 1, wherein the recess section is open at the mouth end of the filter.

3. A filter according to claim 1 or claim 2, wherein the thread extends through the filter between opposing end faces of the plug of filtration material.

4. A filter according to claim 3, wherein the thread extends parallel to a longitudinal axis of the filter.

5. A filter according to any preceding claim, wherein the thread extends through an inner portion of, and is surrounded by, the filtration material.

6. A filter according to claim 1, wherein the plugwrap extends circumferentially around the filter section and extends longitudinally from said end face thereof to form the recess section.

7. A filter according to any preceding claim, wherein the filter section is a first filter section and the filter further comprises a second filter section.

8. A filter according to claim 7, wherein the first filter section is disposed between the second filter section and the recess section.

9. A filter according to claim 8, wherein the second filter portion comprises a longitudinally extending plug and a particulate material disposed in a circumferential region of said plug.

10. A filter according to claim 9, wherein the particulate material extends to an end of the second filter portion immediately adjacent the first filter portion.

11. A filter according to claim 9 or claim 10, wherein two or more portions of the circumferential region of the second section comprise particulate material spaced circumferentially from one another.

12. A filter according to claim 10 or claim 11, wherein a wrapper is engaged around said longitudinally extending plug, and the particulate material is adhered to the surface of the wrapper.

13. A filter according to any of claims 11 to 14, wherein said longitudinally extending plug further comprises a particulate material interspersed in the filtration material.

14. A filter according to any preceding claim, wherein the thread contains a flavourant and/or a colourant.

15. A smoking article comprising a filter according to any preceding claim.