WO2014158051A1

WO2014158051A1 - Smoking article with a multiple cavity filter

Info

Publication number: WO2014158051A1
Application number: PCT/RU2013/000259
Authority: WO
Inventors: Igor Aleksandrovich KOLTYGA
Original assignee: Philip Morris Products S.A.
Priority date: 2013-03-28
Filing date: 2013-03-28
Publication date: 2014-10-02

Abstract

A smoking article (10) comprises an aerosol generating substrate (12) and a mouthpiece (14) in axial alignment with the aerosol generating substrate (12). The mouthpiece comprises a first segment (18) of filtration material spaced downstream from the aerosol generating substrate (12) to define a first cavity (16) between the aerosol generating substrate (12) and the first segment (18) of filtration material, wherein the first cavity (16) is substantially unfilled. The mouthpiece (14) further comprises a mouth end cavity (20) located between the first segment (18) of filtration material and a mouth end of the mouthpiece (14). A wrapper (22) circumscribes the first segment (18) of filtration material, the first cavity (16) and the mouth end cavity (20).

Description

SMOKING ARTICLE WITH A MULTIPLE CAVITY FILTER

The present invention relates to a smoking article having a mouthpiece comprising a first first cavity and a mouth end cavity.

Filter cigarettes typically comprise a cylindrical rod of tobacco cut filler surrounded by a paper wrapper and a cylindrical filter axially aligned in an abutting end-to-end relationship with the wrapped tobacco rod. Conventionally, the wrapped tobacco rod and the filter are joined by a band of tipping wrapper. The cylindrical filter typically comprises one or more segments of filtration material circumscribed by a paper plug wrap.

A number of smoking articles in which an aerosol generating substrate, such as tobacco, is heated rather than combusted have also been proposed in the art. In heated smoking articles, the aerosol is generated by heating the aerosol generating substrate. Known heated smoking articles include, for example, smoking articles in which an aerosol is generated by electrical heating or by the transfer of heat from a combustible fuel element or heat source to an aerosol generating substrate. During smoking, volatile compounds are released from the aerosol generating substrate by heat transfer from the heat source and entrained in air drawn through the smoking article. As the released compounds cool they condense to form an aerosol that is inhaled by the consumer. Also known are smoking articles in which a nicotine-containing aerosol is generated from a tobacco material, tobacco extract, or other nicotine source, without combustion, and in some cases without heating, for example through a chemical reaction.

It would be desirable to provide a smoking article comprising a mouthpiece which is more cost effective to produce than a conventional filter, which traditionally comprises a single segment of filter material extending along the entire length of the mouthpiece. It would be particularly desirable to provide such a cost effective mouthpiece which also provides an equivalent or improved filtration efficiency compared to conventional filters. It would also be desirable if such a cost effective filter could be constructed and processed on existing manufacturing equipment.

Accordingly, the present invention provides a smoking article comprising an aerosol generating substrate and a mouthpiece in axial alignment with the aerosol generating substrate. The mouthpiece comprises a first segment of filtration material spaced downstream from the aerosol generating substrate to define a first cavity between the aerosol generating substrate and the first segment of filtration material, wherein the first cavity is substantially unfilled. The mouthpiece further comprises a mouth end cavity located between the first segment of filtration material and a mouth end of the mouthpiece. A wrapper circumscribes the first segment of filtration material, the first cavity and the mouth end cavity. The term "substantially unfilled" is used herein to describe a first cavity which is substantially free from solid or liquid materials. Preferably, less than 5% of the first cavity by volume contains solid or liquid material. More preferably, less than 2% of the first cavity by volume contains solid or liquid material. Even more preferably, the first cavity is completed unfilled so that the first cavity contains no solid or liquid material.

As used herein, the terms "upstream" and "downstream" are used to describe the relative positions of elements, or portions of elements, of a smoking article in relation to the direction in which a user draws on the smoking article during use thereof. Smoking articles as described herein comprise a downstream end and an opposed upstream end. In use, a user draws on the downstream end of the smoking article. The downstream end, which is also described as the mouth end, is downstream of the upstream end, which may also be described as the distal end.

Advantageously, smoking articles in accordance with the present invention utilise less material in the mouthpiece and are therefore more cost effective to manufacture when compared with conventional cigarettes having a traditional filter extending from the tobacco rod to the mouth end of the cigarette. Furthermore, by selecting the dimensions of the first cavity and the mouth end cavity appropriately, the mouthpiece of smoking articles according to the present invention can be constructed to the size required for processing on existing manufacturing equipment.

Additionally, despite the smaller amount of filtration material when compared to traditional filter cigarettes, smoking articles in accordance with the present invention can offer levels of filtration that are comparable to traditional filter cigarettes comprising a full-length filter. In this regard, the present inventors have recognised that the substantially unfilled first cavity provides a volume in which part of the particulate phase of the aerosol from the aerosol generating substrate can condense prior to entering the first segment of filtration material.

The condensation of part of the aerosol in the first cavity, in combination with the mouth end cavity, also reduces visible staining of the downstream end of the first segment of filtration material. Specifically, the condensate formed in the first cavity will be trapped by the upstream end of the first segment of filtration material. Furthermore, the portion of the wrapper which surrounds the mouth end cavity generally reduces visibility of the downstream end of the first segment of filtration material so that any staining of the downstream end of the first segment of filtration material which does occur is less visible.

The first cavity preferably has a length of about 10 millimetres or less, more preferably about 7 millimetres or less. Preferably, the first cavity has a length of at least about 5 millimetres. The first segment of filtration material may have a length of about 15 millimetres or less, or about 12 millimetres or less. In some embodiments, the first segment of filtration material has a length of about 10 millimetres or less. Preferably, the first segment of filtration material has a length of at least about 7 millimetres.

The second, or mouth end, cavity preferably has a length of about 7 millimetres or less, more preferably about 5 millimetres or less. Preferably, the mouth end cavity has a length of at least about 3 millimetres. For example, the mouth end cavity may have a length of about 5 millimetres. The mouth end cavity is completely unfilled.

The mouthpiece may have an overall length of between about 20 millimetres and about 35 millimetres, as measured between the downstream end of the aerosol generating substrate and the mouth end of the smoking article. For example, the mouthpiece may have an overall length of about 27 millimetres.

The aerosol generating substrate may have a length of between about 45 millimetres and about 65 millimetres. For example, the aerosol generating substrate may have a length of about 56 millimetres.

The smoking article may have an overall length of between about 75 millimetres and about 90 millimetres, as measured between the upstream end of the smoking article and the mouth end of the smoking article. For example, the smoking article may have an overall length of about 83 millimetres.

The smoking article may have an external diameter (including any tipping wrapper that may be present) of between about 4 millimetres and about 9 millimetres. For example, the smoking article may have a diameter of about 7.8 millimetres.

In some embodiments, the first cavity extends from a downstream end of the aerosol generating substrate to an upstream end of the first segment of filtration material. In these embodiments the construction of the mouthpiece is simplified as no intervening material is required between the upstream end of the mouthpiece and the upstream end of the first segment of filtration material.

In alternative embodiments, the mouthpiece further comprises a second segment of filtration material adjacent the aerosol generating substrate so that the first cavity is between the first and second segments of filtration material, and wherein the wrapper also circumscribes the second segment of filtration material. Preferably, the first cavity extends from a downstream end of the second segment of filtration material to an upstream end of the first segment of filtration material.

In those embodiments comprising a second segment of filtration material, the second segment can increase the filtration level of the mouthpiece by capturing a significant portion of the particulate phase of the aerosol from the aerosol generating substrate before the aerosol enters the first cavity. Moreover, providing a second segment of filtration material upstream of the first cavity can facilitate the assembly of the smoking article during manufacture. Specifically, in those embodiments in which the upstream end of the second segment of filtration material defines the upstream end of the mouthpiece, the upstream end of the second segment of filtration material provides a surface against which the downstream end of the aerosol generating substrate can be abutted when aligning the aerosol generating substrate and the mouthpiece.

The second segment of filtration material preferably has a length of about 10 millimetres or less, more preferably about 7 millimetres or less, even more preferably about 5 millimetres or less. The second segment of filtration material preferably has a length of at least about 3 millimetres. For example, the second segment of filtration material may have a length of about 5 millimetres.

The total length of the filtration material in any of the embodiments described above is preferably at least about 35% of the total length of the mouthpiece, more preferably at least about 45% of the total length of the mouthpiece. Preferably, the total length of the filtration material is less than about 65% of the total length of the mouthpiece, more preferably less than about 55% of the total length of the mouthpiece. A total length of filtration material within these ranges advantageously provides sufficient support to the wrapper to minimise the risk of deformation or collapse of the first cavity and the mouth end cavity during handling of the smoking article, while also ensuring that the first cavity and the mouth end cavity are sufficiently large to provide the benefits of the invention discussed above. In those embodiments in which the mouthpiece comprises a single, first segment of filtration material, the total length of the filtration material is the same as the length of the first segment of filtration material. In those embodiments in which the mouthpiece comprises only first and second segments of filtration material as described above, the total length of the filtration material is the combined length of the first and second segments of filtration material.

In any of the embodiments described above, the difference between the length of the first cavity and the length of the mouth end cavity is preferably less than about 12% of the total length of the mouthpiece, more preferably less than about 8% of the total length of the mouthpiece. The length of the first cavity may be the same as the length of the mouth end cavity. By constructing the mouthpiece so that the difference between the length of the first cavity and the length of the mouth end cavity is within these ranges, the first segment of filtration material is positioned approximately centrally between the upstream end of the first cavity and the downstream end of the mouth end cavity. Such an arrangement maintains the structural integrity of both the first cavity and the mouth end cavity and minimises the risk of deformation or collapse of the first cavity and the mouth end cavity during handling of the smoking article. ln any of the embodiments described above, the mouth end cavity preferably extends from a downstream end of the first segment of filtration material to the mouth end of the mouthpiece. This arrangement simplifies the construction of the mouthpiece by eliminating the need for any additional material between the downstream end of the first segment of filtration material and the mouth end of the mouthpiece.

Preferably, the wrapper does not extend about any part of the aerosol generating substrate. Preferably, the wrapper extends between the downstream end of the aerosol generating substrate and the downstream end of the mouthpiece. Utilising a wrapper which does not extend about any part of the aerosol generating substrate advantageously simplifies the construction of the smoking article, since it allows the mouthpiece to be formed separately from the aerosol generating substrate and then subsequently attached thereto later in the manufacturing process. Additionally, by utilising a wrapper which does not extend about any part of the aerosol generating substrate it is possible to construct the mouthpiece and the aerosol generating substrate with the same external diameter, which facilitates connecting the mouthpiece and the aerosol generating substrate together (for example, with a tipping wrapper).

The wrapper may be a plug wrap and is preferably a stiff plug wrap formed from a high basis weight material to reduce the risk of the first cavity and the mouth end cavity becoming deformed or collapsed by handling of the smoking article. The plug wrap preferably has a basis weight of at least about 50 grams per square meter. Preferably the plug wrap has a basis weight of less than about 115 grams per square meter. In some preferred embodiments, the plug wrap has a basis weight of between about 50 grams per square meter and about 115 grams per square meter.

Using a stiff plug wrap with a basis weight within the range described above advantageously minimises the risk of deformation or collapse of the first cavity and the mouth end cavity when the smoking article is handled during manufacture and subsequently used by the consumer. The stiff plug wrap preferably has a basis weight with the above ranges.

In any of the embodiments described above, the mouthpiece wrapper may be provided with one or more ventilation zones about the first segment of filtration material to achieve a desired level of aerosol delivery to the consumer when the smoking article is smoked. The ventilation zone may be provided around the upstream half of the first segment of filtration material, or the downstream half of the first segment of filtration material. For example, where the aerosol generating material comprises a rod of tobacco, a ventilation zone may be provided about the first segment of filtration material to provide required levels of tar and smoke nicotine (SN) delivery. The ventilation level of the first segment of filtration material may be between about 30% and about 80%, as measured in accordance with ISO 9512:2002. Additionally, or alternatively, the mouthpiece wrapper may be provided with one or more ventilation zones about the first cavity. The ventilation zone may be provided around the upstream half of the first cavity, or the downstream half of the first cavity. A ventilation zone about the first cavity advantageously introduces cooler air into the first cavity as a consumer draws on the smoking article, which results in cooling of the aerosol entering the first cavity from the aerosol generating substrate. Cooling of the aerosol facilitates condensation of the particulate phase of the aerosol and therefore further reduces visible staining of the first segment of filtration material.

To maintain desired levels of aerosol delivery to the consumer when the smoking article is smoked, the ventilation level of the first cavity is preferably less than the ventilation level of the first segment of filtration material. Therefore, the ventilation level of the first cavity is preferably greater than 0% and about 20%, as measured in accordance with ISO 9512:2002.

Ventilation into one or both of the first segment of filtration material and the first cavity may be provided by a plurality of perforations in the wrapper. For example, an on-line laser perforation process may be used to form the required ventilation zones in the wrapper.

One or both of the first and second segments of filtration material preferably comprises a plug of fibrous filtration material, such as cellulose acetate tow or paper. A filter plasticiser may be applied to the fibrous filtration material in a conventional manner, by spraying it onto the separated fibres, preferably before applying any additional material to the filtration material.

The first segment of filtration material (and the second segment, where present) may be selected to provide a required resistance to draw (RTD). Preferably, the first segment of filtration material has a RTD of at least about 30 mm WG (water gauge). Preferably, the first segment of filtration material has a RTD of less than about 120 mm WG.

When present, the second segment of filtration material preferably has a RTD of at least about 10 mm WG. Preferably, the second segment of filtration material has a RTD of less than about 50 mm WG. RTD is measured in accordance with ISO 6565:2002.

Preferably, the aerosol generating substrate comprises a wrapped rod of tobacco which can be combusted to produce smoke. Alternatively, the aerosol generating substrate can be a source of tobacco material, tobacco extract, or other nicotine source, which can be heated, without combustion, to generate an aerosol.

Where the aerosol generating substrate comprises a wrapped rod of tobacco, the level of tar delivery when the smoking article is smoked is preferably less than about 10 mg, more preferably less than about 8 mg, even more preferably less than about 5 mg. The level of tar delivery may be at least about 3 mg. The composition of the mainstream smoke, including the amount of tar delivered, is measured in accordance with ISO 15592-3:2008. To connect the mouthpiece to the aerosol generating substrate, smoking articles in accordance with any of the embodiments described above may include a tipping wrapper circumscribing the mouthpiece and at least a portion of the aerosol generating substrate. The tipping wrapper may comprise paper having a basis weight of less than about 70 grams per square metre, preferably less than about 40 grams per square metre. The tipping wrapper preferably has a basis weight of more than about 20 grams per square metre.

Smoking articles in accordance with the present invention may be filter cigarettes or other smoking articles in which a tobacco material is combusted to form smoke. Alternatively, the smoking articles may be articles in which a tobacco material is heated to form an aerosol, rather than combusted. In one type of heated smoking article, the tobacco material is heated by one or more electrical heating elements to produce an aerosol. In another type of heated smoking article, an aerosol is produced by the transfer of heat from a combustible or chemical heat source to a physically separate tobacco material, which may be located within, around or downstream of the heat source. The present invention further encompasses smoking articles in which a nicotine-containing aerosol is generated from a tobacco material without combustion, and in some cases without heating, for example through a chemical reaction.

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

Figure 1 shows a smoking article in accordance with a first embodiment of the present invention; and

Figure 2 shows a smoking article in accordance with a second embodiment of the present invention.

The filter cigarette 10 shown in Figure 1 comprises a wrapped rod 12 of tobacco cut filler which is attached at one end to an axially aligned filter 14. The filter 14 comprises a single segment 18 of cellulose acetate tow and a first cavity 16 provided between the tobacco rod 12 and the filter segment 18. The entire volume of the first cavity 16 is free from solid and liquid materials so that the first cavity 16 is completely empty. The filter 14 also comprises a mouth end cavity 20 which extends between the downstream end of the filter segment 18 and the mouth end of the cigarette 0. A stiff paper plug wrap 22 circumscribes the first cavity 16, the filter segment 18 and the mouth end cavity 20 to form the filter 14. A paper tipping wrapper 24 circumscribes the filter 14 and a portion of the tobacco rod 12 to join the tobacco rod 12 and the filter 14 together. The thicknesses of the plug wrap 22 and the tipping wrapper 24 have been exaggerated in the Figure for clarity.

Figure 2 shows a filter cigarette 30 in accordance with a second embodiment of the present invention. The filter cigarette 30 shown in Figure 2 is identical to the filter cigarette 10 shown in Figure 1 with the exception of an additional filter segment 32. The additional filter segment 32 comprises cellulose acetate tow and is provided at the upstream end of the first cavity 16 and adjacent to the tobacco rod 12.

Examples

Example 1

An exemplary filter cigarette in accordance with the embodiment shown in Figure 1 comprises a cigarette length of 83 millimetres and an external cigarette diameter (including the tipping paper) of 7.8 millimetres. The filter has a length of 27 millimetres measured from the downstream end of the tobacco rod to the mouth end of the cigarette. The first cavity has a length of 7 millimetres, the filter has a length of 15 millimetres and the mouth end cavity has a length of 5 millimetres. The tobacco rod has a length of 56 millimetres and the cut width of the tobacco used to form the tobacco rod is 0.9 millimetres.

The tipping paper has a length of 32 millimetres and includes a ventilation zone positioned about the filter segment. The ventilation zone is formed using on-line laser perforation.

Suitable RTD values for the filter segment include about 40 mm WG, about 70 mm WG and about 120 mm WG, measured in accordance with ISO 6565:2002. Using filter segments with these RTD values would be expected to give a tar delivery of about 10 milligrams, about 8 milligrams and about 5 milligrams respectively, measured in accordance with ISO 15592-3.2008.

Example 2

An exemplary filter cigarette in accordance with the embodiment shown in Figure 2 comprises a cigarette length of 83 millimetres and an external cigarette diameter (including the tipping paper) of 7.8 millimetres. The filter has a length of 27 millimetres measured from the downstream end of the tobacco rod to the mouth end of the cigarette. The upstream filter segment has a length of 5 millimetres, the first cavity has a length of 7 millimetres, the downstream filter segment has a length of 10 millimetres and the mouth end cavity has a length of 5 millimetres. The tobacco rod has a length of 56 millimetres and the cut width of the tobacco used to form the tobacco rod is 0.9 millimetres.

The tipping paper has a length of 32 millimetres and includes a ventilation zone positioned about the downstream filter segment. The ventilation zone is formed using on-line laser perforation. Three variations of the cigarette are constructed using three different filter RTD values (combined RTD for both filter segments): about 40 mm WG, about 70 mm WG and about 120 mm WG, measured in accordance with ISO 6565:2002. The cigarettes are tested using the smoking test described in ISO 15592-3:2008 and the ventilation test described in ISO 9512:2002 to obtain the following results:

Cigarette RTD (mm WG) 73 93 114

Tar (mg) 9.9 8.0 4.9

SN (mg) 0.55 0.44 0.28

Carbon monoxide (mg) 10.2 9.3 6.5

Puff counts 5.3 5.4 5.7

Ventilation (%) 17 23 41

Claims

1. A smoking article comprising:

an aerosol generating substrate; and

a mouthpiece in axial alignment with the aerosol generating substrate, the mouthpiece comprising:

a first segment of filtration material spaced downstream from the aerosol generating substrate to define a first cavity between the aerosol generating substrate and the first segment of filtration material, wherein the first cavity is substantially unfilled;

a mouth end cavity located between the first segment of filtration material and a mouth end of the mouthpiece; and

a wrapper circumscribing the first segment of filtration material, the first cavity and the mouth end cavity.

2. A smoking article according to claim 1 , wherein the first cavity extends from a downstream end of the aerosol generating substrate to an upstream end of the first segment of filtration material.

3. A smoking article according to claim 1, wherein the mouthpiece further comprises a second segment of filtration material adjacent the aerosol generating substrate so that the first cavity is between the first and second segments of filtration material, and wherein the wrapper also circumscribes the second segment of filtration material.

4. A smoking article according to claim 3, wherein the first cavity extends from a downstream end of the second segment of filtration material to an upstream end of the first segment of filtration material.

5. A smoking article according to claim 3 or 4, wherein the second segment of filtration material has a length of 5 millimetres or less.

6. A smoking article according to any of claims 3 to 5, wherein the second segment of filtration material comprises a plug of cellulose acetate tow.

7. A smoking article according to any of claims 3 to 6, wherein the second segment of filtration material has a resistance to draw (RTD) of between about 10 mm WG and about 50 mm WG measured in accordance with ISO 6565:2002.

8. A smoking article according to any preceding claim, wherein the mouth end cavity extends from a downstream end of the first segment of filtration material to the mouth end of the mouthpiece.

9. A smoking article according to any preceding claim, wherein the wrapper is provided with one or more ventilation zones overlying at least a portion of the first segment of filtration material.

10. A smoking article according to any preceding claim, wherein the wrapper is provided with one or more ventilation zones overlying at least a portion of the first cavity.

11. A smoking article according to claim 10, wherein the ventilation level of the first cavity is less than the ventilation level of the first segment of filtration material.

12. A smoking article according to any preceding claim, wherein the resistance to draw (RTD) of the first segment of filtration material is between about 30 mm WG and about 120 mm WG measured in accordance with ISO 6565:2002.

13. A smoking article according to any preceding claim, wherein the tar delivery of the smoking article is between about 3 mg and 10 mg when subjected to a smoking test in accordance with ISO 15592-3:2008.

14. A smoking article according to any preceding claim, wherein the first segment of filtration material comprises a plug of cellulose acetate tow.

15. A smoking article according to any preceding claim, wherein the aerosol generating substrate is a tobacco rod, the smoking article further comprising a tipping paper securing the mouthpiece in axial alignment with the tobacco rod.