Smoking article having concentric filter segment

Abstract

 There is provided a smoking article comprising an aerosol generating substrate and a mouthpiece attached to the aerosol generating substrate. The mouthpiece includes a concentric segment, which comprises a central core portion formed of rigid porous filtration material, and a periphery portion circumscribed about the central core portion, the periphery portion being formed of a deformable material.

Description

[0001] The present invention relates to a smoking article mouthpiece having a concentric segment, and a smoking article incorporating such a concentric segment.

[0002] Filter cigarettes typically comprise a rod of tobacco cut filler surrounded by a paper wrapper and a cylindrical filter aligned in end-to-end relationship with the wrapped tobacco rod, with the filter attached to the tobacco rod by tipping paper. In conventional filter cigarettes, the filter may consist of a plug of cellulose acetate tow wrapped in porous plug wrap. Filter cigarettes with multi-component filters that comprise two or more segments of filtration material for the removal of particulate and gaseous components of the mainstream smoke are also known.

[0003] A number of smoking articles in which an aerosol forming 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 forming 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 forming substrate. During smoking, volatile compounds are released from the aerosol forming 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.

[0004] It is known to provide a sorbent material, such as activated carbon, within the filter of a smoking article as a means to reduce the level of certain smoke constituents. Such sorbent material has typically been provided in the form of a plurality of particles, which can be dispersed amongst the fibres of a filter segment, or provided in a cavity within the filter. However, in some cases, the particles of sorbent material can undesirably migrate in the filter, and potentially escape from the filter entirely. This is often referred to as "particle-breakthrough".

[0005] One way to avoid this problem is to form a porous rigid element, in which the particles of activated carbon have been bound together with a binder. However, such porous rigid elements have principally been used in the water industry, and are notably different from the components normally used to construct filters for smoking articles. There are therefore various challenges that need to be overcome in order to efficiently and effectively incorporate such a porous rigid element into a mouthpiece for a smoking article.

[0006] According to a first aspect of the present invention there is provided a smoking article comprising an aerosol generating substrate and a mouthpiece attached to the aerosol generating substrate. The mouthpiece includes a concentric segment, which comprises a central core portion formed of rigid porous filtration material, and a periphery portion circumscribed about the central core portion, the periphery portion being formed of a deformable material.

[0007] According to a second aspect of the present invention there is provided a mouthpiece for a smoking article. The mouthpiece includes a concentric segment, which comprises a central core portion formed of rigid porous filtration material, and a periphery portion circumscribed about the central core portion, the periphery portion being formed of deformable material.

[0008] By providing a periphery portion formed of a deformable material around a central core portion formed of rigid porous filtration material, the mouthpiece or smoking article of the present invention can be manufactured more easily, in a conventional manner. In particular, in a conventional filter or cigarette making process, when a tipping paper or filter wrapper is provided around one or more filter segments, the one or more filter segments are typically compressed in order to ensure that the filter wrapper or tipping paper is appropriately adhered or otherwise secured to the rest of the mouthpiece. Such a manufacturing step would be problematic if the filter segment were formed entirely of a rigid porous material, as the rigid porous material would be unable to compress during the wrapping step. This could result in a poorly secured tipping paper or wrapper, or in breakage of the manufacturing machinery or the rigid porous material. However, by ensuring that there is a periphery portion of a deformable material surrounding the core of rigid porous material, the concentric segment can still be compressed when the filter wrapper or tipping paper is applied, thus allowing the filter to be manufactured with conventional processes and machinery. Furthermore, by providing a periphery portion of a deformable material around the core of rigid porous material, the concentric segment may still provide an external feel to a consumer, similar to that typically associated with conventional smoking article filters.

[0009] The term "rigid material" is used herein to mean a material, which does not substantially change its shape and/or dimensions, either elastically or plastically, when subjected to a compressive force. For example, the rigid material of the central core portion may have a hardness of at least about 97%.

[0010] The term "hardness" used throughout this specification denotes the resistance to deform. Hardness is generally expressed as a percentage. Figure 2 shows a cylindrical element 101 before applying a load F and the same cylindrical element 103 whilst applying load F. The cylindrical element 101 before load F has been applied has a diameter D_s. The cylindrical element 103 after applying a set load for a set duration (but with the load still applied) has a (reduced) diameter D_d. The depression is d = D_s - D_d. Referring to Figure 2, hardness is given by:


where D_s is the original (undepressed) diameter of the cylindrical element being tested, and D_d is the depressed diameter of the cylindrical element being tested after applying a set load for a set duration. The harder the material, the closer the hardness is to 100%. The term 'hardness' is normally used to refer to a cylindrical portion of a fully assembled smoking article, such as a filter segment or a section of the tobacco rod. The test below is therefore described in respect of such a portion of a smoking article. However, it will be appreciated that the test is equally applicable to other components of a smoking article, such as the central core portion of the present invention. If the hardness of the central core portion of the smoking article is to be tested, then all surrounding material (including the material of the periphery portion) should first be removed from the concentric segment, so that the only material which is subject to compression is the material of the central core portion itself.

[0011] As is described in more detail below, and generally known in the art, to determine the hardness of a portion (such as a filter) of a smoking article, smoking articles should be aligned parallel in a plane and the same portion of each smoking article to be tested should be subjected to a set load for a set duration. This test is performed using a known DD60A Densimeter device (manufactured and made commercially available by Heinr. Borgwaldt GmbH, Germany), which is fitted with a measuring head for cigarettes and with a cigarette receptacle.

[0012] The load is applied using two load applying cylindrical rods, which extend across the diameter of all of the smoking articles at once. According to the standard test method for this instrument, the test should be performed such that twenty contact points occur between the smoking articles and the load applying cylindrical rods. In some cases, the filters to be tested may be long enough such that only ten smoking articles are needed to form twenty contact points, with each smoking article contacting both load applying rods (because they are long enough to extend between the rods). In other cases, if the filters are too short to achieve this, then twenty smoking articles should be used to form the twenty contact points, with each smoking article contacting only one of the load applying rods, as further discussed below.

[0013] Two further stationary cylindrical rods are located underneath the smoking articles, to support the smoking articles and counteract the load applied by each of the load applying cylindrical rods. Such an arrangement is described in more detail below, and shown in Figures 3 to 5.

[0014] For the standard operating procedure for such an apparatus, an overall load of 2 kg is applied for a duration of 20 seconds. After 20 seconds have elapsed (and with the load still being applied to the smoking articles), the depression in the load applying cylindrical rods is determined, and then used to calculate the hardness from the above equation. The temperature is kept in the region of 22 degrees Centigrade ± 2 degrees. The test described above is referred to as the DD60A Test. The DD60A Test and corresponding apparatus are described in more detail below in relation to Figures 3 to 5. The standard way to measure the filter hardness is when the smoking article is unsmoked.

[0015] The concentric segment may have any suitable shape. However, preferably, the concentric segment is substantially cylindrical, with the central core portion having a substantially cylindrical shape and the periphery portion having a substantially annular shape.

[0016] The structure and properties of the central core portion and the periphery portion may be adjusted to provide a desired resistance to draw (RTD) for the concentric segment. Preferably, the resistance to draw (RTD) of the central core portion is less than the RTD of the periphery portion. For example, the RTD of the central core portion may be less than about 90% of the RTD of the periphery portion or less than about 75% of the RTD of the periphery portion or less than about 65% of the RTD of the periphery portion. In many embodiments, the RTD of the central core portion is about 10% to about 90% or about 20% to about 75%, or about 30% to about 65% of the RTD of the periphery portion. Such arrangements can allow the concentric segment to act like a flow restrictor, in which flow of smoke is diverted through the smaller cross-sectional area occupied by the central core portion, rather than the entire cross-sectional area of the mouthpiece. This can be particularly advantageous if the central core portion contains a smoke modifying material, such as a sorbent.

[0017] The resistance to draw (RTD) of the smoking articles of the present disclosure can vary. In many embodiments the RTD of the smoking article is between about 70 to 130 mm H₂O. The RTD of a smoking article (or a portion thereof) refers to the static pressure difference between the two ends of the specimen when it is traversed by an air flow under steady conditions in which the volumetric flow is 17.5 millilitres per second at the output end. The RTD of a specimen can be measured using the method set out in ISO Standard 6565:2002.

[0018] The RTDs of the outer periphery portion and the central core portion can be tested by first separating the concentric sorbent segment from the rest of the filter. The RTD of the outer periphery portion of the concentric sorbent segment can then be tested by blocking off the upstream and downstream ends of the central core portion of the concentric sorbent segment and utilizing the RTD test method described above. The RTD of the central core portion of the concentric sorbent segment can be tested by blocking off the upstream and downstream ends of the outer periphery portion of the concentric sorbent segment and utilizing the RTD test method described above. The portions of the concentric sorbent segment can be blocked off with an impermeable material, for example an impermeable adhesive.

[0019] The rigid porous material of the central core portion may have any suitable structure. Preferably, however, the rigid porous material comprises a mass of particles bound together by a binder. This can take the form of a matrix type structure, where the binder forms one or more bridges between at least some of the particles and another adjacent particle or particles. This can define a plurality of random passageways in the rigid porous core, through which smoke may flow.

[0020] The particles of the rigid porous material may be inert. That is, the particles may not interact with constituents of the smoke. However, preferably, the rigid porous material comprises a mass of smoke-modifying particles. The mass of smoke-modifying particles can be formed of removing materials, such as catalysts or sorbents, which capture or convert constituents of the mainstream smoke passing though the filter. Alternatively or additionally, the mass of smoke-modifying particles can be formed of releasing materials, which release compounds, such as flavourant, into the mainstream smoke passing though the filter.

[0021] Materials that capture smoke constituents include sorbents such as activated carbon, coated carbon, active aluminium, aluminium oxide, zeolites, sepiolites, molecular sieves, and silica gel, for example. Materials that capture smoke constituents also include ion exchange materials such as amino acids, amino smoke-modifying particles, and polyelectrolytes, for example. Materials that convert smoke constituents include catalysts such as manganese, chromium, iron, cobalt, nickel, copper, zirconium, tin, zinc, tungsten, titanium, molybdenum, and vanadium materials, and any oxide thereof; titania, ceria and gold or gold on titania; and nanostructures such as graphene, graphene oxide, functionalised graphene and carbon nanotubes for example.

[0022] Releasing materials are materials that release compounds into the mainstream smoke passing through the central core portion, and include flavourant material. Flavourant material can include particles of a sorbent, cellulosic material, or porous glass beads, which are impregnated with liquid flavourant or particulate material such as herbaceous material, or any combination thereof. Flavourant materials include, but are not limited to, materials that contain natural or synthetic menthol, peppermint, spearmint, coffee, tea, spices (such as cinnamon, clove and ginger), cocoa, vanilla, fruit flavours, chocolate, eucalyptus, geranium, eugenol, agave, juniper, anethole and linalool.

[0023] Preferably, however, the rigid porous filtration material of the concentric segment comprises a mass of sorbent particles, such as activated carbon particles, bound together by a binder.

[0024] Preferably the binder is a thermoplastic binder. Suitable materials for the binder include polyolefins, polyesters, polyethylene, polyamides (or nylons), polyacrylics, polystyrenes, polyvinyls, and cellulose derivates. Suitable materials for the rigid porous filtration material of the central core portion are further described in WO 2012/047348A1.

[0025] The periphery portion of the concentric segment is formed of a deformable material to provide desired flexibility and elasticity properties to the peripheral region of the concentric segment. The periphery portion may therefore comprise any suitable material which can deform. That is, the term "deformable material" should be understood to be a material, which can change its shape and/or dimensions, either elastically or plastically, when subjected to a compressive force. Preferably, the deformable material is resiliently deformable, such that it can at least partially return to its original shape and/or dimension after it has been subjected to a compressive force, for example return to 90%, and more preferably 95%, of its original dimensions after being subjected to the DD60A test described below. This helps the concentric segment to be partially deformed during manufacture and handling of the smoking article, so that it may be subjected to the same processing and handling as that normally applied to a conventional smoking article mouthpiece.

[0026] The deformation of the concentric segment may therefore also be defined in terms of a percentage hardness value, as is described above in relation to the rigid porous material of the central core portion. This may be determined in accordance with the DD60A Test that is described above, and also in more detail below in relation to Figures 3 to 5. Accordingly, preferably the concentric segment has a hardness of less than about 96%, more preferably less than about 95%, according to the DD60A test described above. Preferably, the concentric segment has a hardness of at least about 70%, more preferably at least about 80%, according to the DD60A test described above. Such hardness values for the concentric segment, will allow the segment to be deformed sufficiently far enough for the mouthpiece to be manufactured using existing machinery and techniques, and for the mouthpiece to have a general feel, similar to that of a convention smoking article mouthpiece.

[0027] As noted above, in a conventional filter or cigarette making process, when a wrapper is provided around one or more filter segments, the one or more filter segments are typically compressed in order to appropriately adhere or otherwise secure the filter wrapper or tipping paper to the rest of the mouthpiece. Typically, a reduction of at least 1 mm in the filter's cross sectional dimension is required for the wrapper or tipping paper to be appropriately secured. Therefore, preferably the periphery portion is formed of a deformable material such that a cross sectional dimension of the concentric segment is reduced by at least 1 mm in response to a compressive force of less than 30 Newtons, more preferably less than 20 Newtons, and even more preferably less than 15 Newtons, when using a device having a circular foot with a cross-sectional area of about 110 mm², such as an Alluris FMT-310 Force Tester (commercially available from Alluris Gmbh & Co .KG, Germany). The cross sectional dimension of the concentric segment should be taken in a direction perpendicular to the longitudinal axis of the mouthpiece or filter. The periphery portion should preferably have a thickness of at least 1 mm, more preferably at least 1.5 mm, and even more preferably at least 2 mm. The thickness of the periphery portion is the distance between the outer surface of the concentric segment and the outer surface of the central core portion in the radial direction of the concentric segment.

[0028] The deformable material may have a porous or non-porous structure. In some preferred embodiments, the deformable material may have a non-porous structure, so that it provides a high resistance to draw, and thus enhances the diversion of smoke flow through the central core portion of the concentric segment. This can be particularly advantageous if the central core portion contains a smoke modifying material, such as a sorbent. Such non-porous materials may include, for example, polyethylene, polypropylene or a combination thereof.

[0029] As noted above, the periphery portion should comprise a material which can deform. Therefore, in some embodiments, the periphery portion preferably comprises fibrous material, more preferably fibrous cellulose-based material. The fibrous material may comprise a nonwoven web of cellulosic material such as paper, and in particular, creped paper. Alternatively or additionally, the fibrous material may comprise a fibrous tow or randomly orientated fibres. Suitable fibrous materials include polylactic acid, poly(lactic-co-glycolic) acid, and cellulose or cellulose-based materials such as cellulose acetate or other cellulose derivatives.

[0030] In some preferred embodiments, the periphery portion comprises a foam material, such as a thermoplastic foam or an injected or co-extruded foam. Suitable foam materials can include polyethelyne, ethylene vinyl acetate and polypropylene.

[0031] A particularly preferred material for the periphery portion is a fibrous filtration material, such as cellulose acetate tow. In cases where fibrous filtration material such as cellulose acetate is used, a plasticizer may be used in order to fuse the fibres together and create a higher RTD in the periphery portion of the concentric segment.

[0032] Preferably, the deformable material of the periphery portion abuts the rigid porous material of the central core portion. Preferably, the deformable material of the periphery portion abuts a wrapper circumscribing the concentric segment. Alternatively, the concentric segment may include additional materials or layers disposed between the deformable material of the periphery portion and a circumscribing wrapper or the rigid porous material of the central core portion. For example, a layer of material may be disposed between the rigid porous material and the central core portion. This layer could be a porous material, but is preferably a substantially non-porous material having a permeability of less than about 500 Coresta Units, more preferably less than about 100 Coresta Units. The layer could have any suitable thickness in the radial direction of the mouthpiece.

[0033] Preferably, the central core portion has a cross-sectional area of less than about 80% of the cross-sectional area of the mouthpiece, measured on either the finished smoking article or a mouthpiece element such as a filter, taken perpendicular to the longitudinal axis of the smoking article or mouthpiece. Alternatively or additionally, preferably the central core portion has a cross-sectional area of at least about 30% of the cross-sectional area of the smoking article or mouthpiece.

[0034] Preferably, the periphery portion has a cross-section area of at least 20% of the cross sectional area of the mouthpiece, measured on either the finished smoking article or a mouthpiece element such as a filter, taken perpendicular to the longitudinal axis of the smoking article or mouthpiece. Alternatively or additionally, the periphery portion has a cross-section area of less than 70% of the cross sectional area of the smoking article or mouthpiece. Having such a size of periphery portion can allow the deformable material of the periphery portion to have sufficient space for the mouthpiece of the invention to be manufactured using existing machinery and processes.

[0035] Preferably, the mouthpiece includes a ventilation zone. The ventilation zone admits ambient air into the smoking article and combines the admitted ambient air with mainstream smoke. The ventilation zone may be provided by a plurality of apertures or perforations formed in the tipping paper. This plurality of apertures or perforations can circumnavigate the circumference of the smoking article.

[0036] The ventilation zone may provide any suitable ventilation level, such as a ventilation of between about 10% and about 90%. However, preferably the ventilation level is at least about 60%, for example between about 60% and about 90%. As the concentric segment of the invention may act as a flow restrictor, and thereby increase the RTD of the mouthpiece to an acceptable level, a ventilation level of at least 60% may be acceptable in some embodiments of the present invention.

[0037] The term "ventilation level" refers to the percentage by volume of air that is included in the smoke delivered to the consumer from the mouth end of the filter with the ventilation completely open. The level of ventilation achieved by the ventilation elements can be determined using ISO test method 9512:2002.

[0038] Preferably, the ventilation zone is disposed adjacent to the upstream end of the concentric sorbent segment. While not wishing to be bound by any particular theory, it is believed that positioning the ventilation zone near or adjacent to the upstream end of the concentric segment concentrates the smoke toward the central core portion and any sorbent material that may be contained therein, as the smoke flows through the concentric segment. Preferably, the ventilation zone is disposed within about 5 mm or within about 3 mm of the upstream end of the concentric segment, for example upstream of and within about 5 mm or within about 3 mm of the upstream end of the concentric segment.

[0039] In some embodiments the mouthpiece only includes the concentric segment. In some other embodiments, the mouthpiece includes one or more additional segments. The one or more additional segments may be disposed upstream or downstream of the concentric segment, or both. However, including an additional segment downstream of the concentric segment is particularly preferred as this can obscure the concentric segment from the consumer.

[0040] In some preferred embodiments, the mouthpiece may include the concentric segment in axial alignment with a second segment separating the concentric segment from the aerosol generating substrate. In some preferred embodiments, the mouthpiece includes the concentric segment in axial alignment with, and separating the second filter segment from, a third filter segment. The concentric segment has an upstream end and a downstream end. The upstream end extends toward the aerosol generating substrate.

[0041] Where the mouthpiece includes one or more additional segments, these may be formed from any suitable material. However, preferably the one or more additional segments are formed from a deformable material, and more preferably the one or more additional segments are formed from substantially the same material as the periphery portion of the concentric filter segment. This can help to ensure that the peripheral portion of the entire mouthpiece has generally consistent compression properties, thus assisting with the manufacturing and general feel of the mouthpiece.

[0042] The smoking article may be a conventional filter cigarette, such that the aerosol generating substrate is a tobacco rod and the mouthpiece comprises a filter having one or more segments of filtration material. In such embodiments, the concentric segment could be a concentric filter segment, and any wrappers circumscribing the mouthpiece (or filter) could be a single filter wrapper, combi-filter wrapper or tipping paper.

[0043] Alternatively, the smoking article may be one in which an aerosol forming substrate, such as tobacco, is heated rather than combusted, or one 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.

[0044] The terms "upstream" and "downstream" refer to relative positions of elements of the smoking article or filter described in relation to the direction of mainstream smoke as it is drawn from the aerosol generating substrate and through the filter or mouthpiece.

[0045] The invention will be further described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a longitudinal cross section of a smoking article according to the described embodiment.

Figure 2 illustrates the definition of hardness;

Figure 3 illustrates a perspective view of an apparatus for determining the hardness of a filter or a smoking article, in a first configuration;

Figure 4 illustrates a side view of the apparatus of Figure 3, in a first configuration;

Figure 5 illustrates a side view of the apparatus of Figure 3, in a second configuration;

Figure 6 is a graph showing hardness (%) for three samples; and

Figure 7 is a graph showing the Force required to reduce the diameter of each of three different samples by at least 1 mm.

[0046] Figure 1 is a perspective view of a smoking article 100 according to an embodiment of the invention. The smoking article 100 includes an aerosol forming substrate in the form of a generally cylindrical tobacco rod 101 and a mouthpiece in the form of a generally cylindrical filter 103. The tobacco rod 101 and filter 103 are axially aligned in an end-to-end relationship, preferably abutting one another. The tobacco rod 101 includes an outer wrapper 105 circumscribing the smoking material. The tobacco is preferably a shredded tobacco or tobacco cut filler. The filter 103 includes a filter wrapper (not shown) circumscribing the filter material. The tobacco rod 101 has an upstream, lit end 109.

[0047] The filter 103 is attached to the tobacco rod 101 by tipping material 117 which circumscribes the entire length of the filter 103 and an adjacent region of the tobacco rod 101. The tipping material 117 is shown partially removed from the smoking article in Figure 1, for clarity. The filter had an upstream segment 111 formed of cellulose acetate tow and a downstream concentric segment 113. The downstream concentric segment 113 has a core portion 120 and a periphery portion 125. The core portion 120 is formed of the rigid porous filtration material comprising a mass of activated carbon particles bound together by a polypropylene binder. The periphery portion 125 is formed of cellulose acetate tow.

[0048] The hardness of three different samples (Sample 1, Sample 2 and Sample 3) was tested using a known DD60A Densimeter (manufactured and made commercially available by Heinr. Borgwaldt GmbH, Germany) device, which was fitted with a measuring head for cigarettes and with a cigarette receptacle, as described above. The samples were tested by following the method which is recommended for the known DD60A Densimeter device (manufactured and made commercially available by Heinr. Borgwaldt GmbH, Germany). That is, a sample of smoking articles were held in parallel alignment, and subjected to an overall load of 2 kg, for a period of 20 seconds, and the diameters of the smoking articles before and after compression were recorded. The depression was used to determine the hardness (%) of each smoking article.

[0049] The apparatus for testing the hardness of the smoking articles filters is shown in Figures 3, 4 and 5 and the measured hardness values are shown in Figure 6.

[0050] Figure 3 is a perspective view of an apparatus 4, such as a DD60A Densimeter device, for determining the hardness of a filter of a smoking article. The apparatus includes two parallel load applying rods 24 positioned over a support plate 30. The support plate 30 includes two parallel, spaced apart walls 12, with each wall 12 having ten equally spaced recesses. The recesses are arranged to prevent the smoking articles 10 from contacting one another during testing.

[0051] As can be seen in Figure 3, ten identically designed smoking articles 10 are aligned parallel in a plane, and placed on underlying cylindrical rods 14. The smoking articles 10 extend between corresponding recesses in the walls 12 to hold the smoking articles in place. The underlying cylindrical rods 14 extend parallel to the walls 12. Each smoking article 10 contacts the underlying rods 14 at two points, making for twenty total points of contact between the smoking articles to be tested and the underlying rods 14.

[0052] To test the hardness of a smoking article's filter, the smoking articles should be positioned such that the portion of the filter to be tested is in contact with the underlying rods 14. If the filter is too short and the portion of the filter to be tested either does not contact both rods or contacts the rods very close to the ends of the portion of the filter to be tested, then it would appreciated that this could be achieved by using twenty cigarettes in a back-to-back configuration, such as that shown in Figure 4.

[0053] As shown, the concept of the DD60A Test is that the underlying cylindrical rods contact the sample material to be tested at twenty contact points. If the filter is sufficiently long to extend across the underlying rods, then the twenty contact points can be provided with ten samples (as shown in Figure 3). If the filter is not sufficiently long, then the twenty contact points can be provided with twenty samples, as shown in Figure 4.

[0054] As can be seen in Figure 4, portions of the tobacco rods have been removed from each smoking article 10, and the filter portion of each smoking article 10 rests on a respective cylindrical rod 14. In the present case, the hardness of the mouth end segment is being tested, and therefore it is this portion of the filter which rests on the rod 14, and the mouth end segment is approximately centred on the rods 14. If necessary, the tips of the smoking articles extending away from the cylindrical rods 14 may be supported by an underlying supporting means to prevent pivoting of the smoking articles.

[0055] The apparatus is shown in Figure 4 in a first configuration, in which the two load applying cylindrical rods 24 are raised above and out of contact from the smoking articles 10. To test the hardness of the smoking articles, the load applying cylindrical rods 24 are lowered to a second configuration, to come into contact with the smoking articles 10, as shown in Figure 5. When in contact with the smoking articles 10, the load applying rods 24 impart an overall load of 2kg across the twenty contact points of the smoking articles 10 for a duration of 20 seconds. After 20 seconds have elapsed (and with the load still being applied to the smoking articles), the depression in the load applying cylindrical rods 24 across the smoking articles is determined, and then used to calculate the hardness.

[0056] As noted above, the term 'hardness' is normally used to refer to a cylindrical portion of a fully assembled smoking article, such as a filter segment or a section of the tobacco rod. The DD60A test is therefore described in this application in respect of such a portion of a smoking article. However, it will be appreciated that the test is equally applicable to other cylindrical components of a smoking article, such as the central core portion of the present invention. If the hardness of the central core portion of the smoking article is to be tested, then the surrounding material (including the material of the periphery portion) should first be removed from the concentric segment, so that the only material which is subject to compression is the material of the central core portion itself.

Example 1

[0057] The three types of samples tested were:

• Sample 1: Sample 1 was a filter cigarette according to the present invention. That is, the filter had a concentric segment, having a core portion and a periphery portion. The core portion was formed of the rigid porous filtration material comprising a mass of activated carbon particles bound together by a polypropylene binder. This material is commercially available under the brand name CELFX® by Celanese GmbH, Germany. The periphery portion was formed of cellulose acetate tow. The concentric segment was circumscribed by a filter wrapper having a basis weight of about 26 gm^-2 and a thickness of about 40 µm. The load applying rods of the apparatus of Figures 3 to 5 were applied to the concentric segment of the filter and the hardness value was measured.
• Sample 2: Sample 2 was a cylinder of rigid porous filtration material comprising a mass of activated carbon particles bound together by a polypropylene binder. This material is commercially available under the brand name CELFX® by Celanese GmbH, Germany. The cylinder of rigid porous filtration material was not surrounded by any material, such that the load applying rods of the apparatus of Figures 3 to 5 could be applied directly to the rigid porous material and the hardness value measured.
• Sample 3: Sample 3 was a known filter cigarette. The filter contained a plug of cellulose acetate tow circumscribed by a filter wrapper having a basis weight of about 110 gm^-2 and a thickness of about 140 µm. The load applying rods of the apparatus of Figures 3 to 5 were applied to the cellulose acetate segment of the filter and the hardness value was measured.

[0058] As can be seen in Figure 6, Sample 2 (the rigid porous material) has a significantly higher hardness value than that measured for the known filter (Sample 3). However, Sample 1 (a filter according to the present invention) has a hardness value similar to that measured for the known filter (Sample 3). Sample 1 can therefore be seen to exhibit similar resistance to deformation properties to that of a known filter, and therefore may be capable of being manufactured using conventional processes and machinery.

Example 2

[0059] Samples 1, 2 and 3 described above in respect of Figure 6, were also tested to determine the force required to reduce the diameter of the filter or cylinder by at least 1 mm, using an Alluris FMT-310 Force Tester having a circular foot with a cross-sectional area of about 110 mm² (commercially available from Alluris Gmbh & Co .KG, Germany). The results of this test are shown in Figure 7.

Example 3

[0060] Two differently designed smoking articles were prepared and tested. The first sample (Sample A) was a reference cigarette, comprising a tobacco rod attached to a single segment filter. The filter was formed of cellulose acetate tow and had a total length of 27 mm, and diameter of 7.85 mm.

[0061] The second smoking article (Sample B) was a smoking article in accordance with the present invention, and had the structure generally shown in Figure 1. That is, Sample B comprised a filter attached to a tobacco rod. The filter had an upstream segment of cellulose acetate and a downstream concentric segment, having a core portion and a periphery portion. The core portion was formed of the rigid porous filtration material comprising a mass of activated carbon particles bound together by a polypropylene binder. This material is commercially available under the brand name CELFX® by Celanese GmbH, Germany. The periphery portion was formed of cellulose acetate tow.

[0062] The total filter length of Sample B was 27 mm, with the upstream filter segment having a length of 15 mm. The concentric filter segment had a length of 12 mm, with the central core portion having a diameter of 5.4 mm. The filter diameter for Sample B was 7.85 mm.

[0063] Samples A and B were subjected to Health Canada Intense smoking regime (55cm³ puff volume, 30 second puff frequency, 2 second puff duration and 100% vent blocking). The results of the smoking test are depicted in table 1 below:

Table 1

Test Cigarettes	Units	SAMPLE A	SAMPLE B
Cigarette Filter RTD	mmWG	95	81

Analytical Data - Under Health Canada Intense Regime
CO	mg	24.0	24.0
SN	mg	1.8	2.0
TAR	mg	24.0	27.2
CO/SN	(ratio)	13.2	12.0
CO Reduction (per SN)	%		9

Claims

1. A smoking article comprising:

an aerosol generating substrate; and

a mouthpiece attached to the aerosol generating substrate, the mouthpiece comprising a concentric segment comprising:

a central core portion formed of rigid porous filtration material; and

a periphery portion circumscribed about the central core portion, wherein the periphery portion is formed of a deformable material.

2. A smoking article according to claim 1, wherein the rigid porous filtration material of the concentric segment comprises a mass of smoke-modifying particles bound together by a binder.

3. A smoking article according to claim 1 or claim 2, wherein the deformable material of the periphery portion comprises fibrous material.

4. A smoking article according to any preceding claim, wherein the central core portion has a cross-sectional area of less than about 80% of the cross-sectional area of the mouthpiece.

5. A smoking article according to any preceding claim, wherein the central core portion has a cross-sectional area of at least about 30% of the cross-sectional area of the mouthpiece.

6. A smoking article according to any preceding claim, wherein the central core portion provides a lower resistance to draw than the periphery portion.

7. A smoking article according to any preceding claim, wherein the periphery portion is formed of a deformable material such that a cross sectional dimension of the concentric segment is reduced by at least 1 mm in response to a compressive force of less than 30 Newtons.

8. A smoking article according to any preceding claim, wherein the mouthpiece further comprises a ventilation zone providing a ventilation level of at least about 60%.

9. A smoking article according to any preceding claim, wherein the mouthpiece further comprises one or more additional filter segments.

10. A smoking article according to claim 9, wherein the one or more additional filter segments are formed from deformable material.

11. A mouthpiece for a smoking article, the mouthpiece comprising:

a concentric segment comprising:

a central core portion formed of rigid porous material; and

a periphery portion circumscribed about the central core portion, the periphery portion being formed of deformable material.

12. A mouthpiece according to claim 11, wherein the central core portion has a cross-sectional area of less than about 80% of the cross-sectional area of the mouthpiece.

13. A mouthpiece according to claim 11 or 12, wherein the deformable material of the periphery portion comprises fibrous material.

14. A mouthpiece according to any one of claims 11 to 13, wherein the rigid porous filtration material of the concentric segment comprises a mass of smoke-modifying particles bound together by a binder.

15. A mouthpiece according to any one of claims 11 to 14, wherein the central core portion provides a lower resistance to draw than the periphery portion.

Drawing