Patent Publication Number: US-2017360084-A1

Title: A smoking article, a filter and a method of manufacturing a smoking article

Description:
TECHNICAL FIELD 
     Embodiments of the invention relate to a smoking article, a filter and a method of manufacturing a smoking article. 
     BACKGROUND 
     The resistance to draw of a smoking article is a measure of the pressure required to force smoke through the smoking article at a certain specified rate. A smoking article can be configured by the manufacturing process to have a resistance to draw within a pre-defined range. The resistance to draw through a smoking article generally drops with increased ventilation. 
     SUMMARY 
     Embodiments of the invention provide, in a first aspect, a smoking article comprising a filter arrangement comprising a first filter section and a second filter section, the second filter section being located downstream of the first filter section and a ventilation arrangement configured to provide a user controllable level of ventilation into the first filter section, wherein a resistance to gaseous flow through the length of the second filter section is lower than a resistance to gaseous flow through the length of the first filter section, and the resistance to gaseous flow through the length of the filter arrangement remains substantially constant as the level of ventilation is varied. 
     The first filter section can have a first tow weight of fibrous filtration material, and the second filter section can have a second tow weight of fibrous filtration material and the second tow weight of fibrous filtration material is lower than the first tow weight of fibrous material. 
     The pressure drop per unit length of the first filter section can be more than 5 mmH 2 O/mm, and the pressure drop per unit length of the second filter section can be less than 5 mmH 2 O/mm. The resistance to gaseous flow through the second filter section can be more than 15 times lower than the resistance to gaseous flow through the first filter section. 
     The first filter section can be formed from a first homogenous filtration material, and the second filter section can be formed from a second homogenous filtration material. 
     The second filter section can be separate from the first filter section, and/or moveable relative to the first filter section to control the ventilation into the first filter section. 
     The smoking article can further comprise a sleeve configured to move relative to the first filter section, wherein the second filter section is fixed within the sleeve, and the level of ventilation is varied by altering a position of the sleeve relative to the first filter section. 
     The sleeve can be rotatable with respect to the first filter section, and the level of ventilation can be varied by altering an angular position of the sleeve relative to the first filter section. 
     The first filter section can have a length of 5 to 25 mm, the second filter section can have a length of 5 to 25 mm, and/or the ventilation arrangement can provide ventilating air at 6 mm to 35 mm from a mouth end of the smoking article. 
     The first and second filter sections can comprise tow filaments, and the first filter section can differ from the second filter section by one or more of: tow weight, number of tow filaments in unit volume, cross-section of tow filaments and degree of crimping. 
     The second filter section can comprise at least one air passage extending longitudinally through the length thereof. 
     The air passage can have a diameter of between 1 and 7 mm. 
     The second filter section can comprise fibrous filtration material formed having an annular cross section. 
     The second filter section can comprise a tube of fibrous filtration material and the air passage can extend along a central longitudinal axis through the length of the second filter section. 
     Embodiments of the invention provide, in a second aspect, a method of manufacturing a smoking article, the method comprising forming a first filter section with a first resistance to gaseous flow through its length, forming a separate second filter section with a second resistance to gaseous flow through its length, wherein the second resistance to gaseous flow is lower than the first resistance to gaseous flow, and assembling the first filter section and second filter section with one or more additional components to form the smoking article, wherein the smoking article is configured to allow the ingress of a selectively variable amount of air. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
         FIG. 1  is a longitudinal cross-sectional view of a part of a smoking article according to a first embodiment of the invention; 
         FIG. 2  is a perspective view of the smoking article illustrated in  FIG. 1 ; 
         FIG. 3  is a longitudinal cross-sectional view of a part of a smoking article according to a second embodiment of the invention; 
         FIG. 4  is a perspective view of the smoking article illustrated in  FIG. 3 ; 
         FIG. 5  is a graph showing the relationship between level of ventilation and open cigarette pressure drop (PD) for an example conventional smoking article and a smoking article according to the invention; 
         FIG. 6 a    is a plan view of a blank forming a wrapper for a smoking article according to a third embodiment of the invention; 
         FIG. 6 b    is a plan view of a rod article to which the blank of  FIG. 6 a    is applied to form the smoking article according to the third embodiment of the invention; 
         FIG. 7 a    is a plan view of a blank for forming a wrapper for a smoking article according to a fourth embodiment; 
         FIG. 7 b    is a longitudinal cross-sectional view of the smoking article according to the fourth embodiment; and 
         FIG. 8  is a schematic flow diagram showing a method of manufacturing a smoking article. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a smoking article  10  according to a first embodiment. The smoking article  10  is a cigarette in the present example. However, other smoking articles can be used, and the term smoking article is used to also refer to cigars or cigarillos, whether based on tobacco, tobacco derivatives, expanded tobacco, reconstituted tobacco or tobacco substitutes and also heat-not-burn products (i.e. products in which flavour is generated from a smoking material by the application of heat without causing combustion of the material) and aerosol generating products such as e-cigarettes. For convenience, these will be referred to as “smoking articles” in this specification. 
     Smoking articles such as cigarettes and their formats are often named according to the cigarette length: “regular” (typically in the range 68-75 mm, e.g. from about 68 mm to about 72 mm), “short” or “mini” (68 mm or less), “king-size” (typically in the range 75-91 mm, e.g. from about 79 mm to about 88 mm), “long” or “super-king” (typically in the range 91-105 mm, e.g. from about 94 mm to about 101 mm) and “ultra-long” (typically in the range from about no mm to about 121 mm). 
     They are also named according to the cigarette circumference: “regular” (about 23-25 mm), “wide” (greater than 25 mm), “slim” (about 22-23 mm), “demi-slim” (about 19-22 mm), “super-slim” (about 16-19 mm), and “micro-slim” (less than about 16 mm). Accordingly, a cigarette in a king-size, super-slim format will, for example, have a length of about 83 mm and a circumference of about 17 mm. Cigarettes in the regular, king-size format are preferred by many customers, namely with a circumference of from 23 to 25 mm and an overall length of from 75 to 91 mm. 
     Each format may be produced with filters of different lengths, smaller filters being generally used in formats of smaller lengths and circumferences. Typically the filter length will be from 15 mm, associated with short, regular formats, to 30 mm, associated with ultra-long super-slim formats. The tipping paper will have a greater length than the filter, for example from 3 to 10 mm longer. 
     Smoking articles and filters described hereinafter can be manufactured in any of the above formats. The smoking article can, for instance, be from 70 to 100 mm in length and from 14 to 25 mm in circumference. 
     The terms ‘upstream’ and ‘downstream’ used herein are relative terms defined in relation to the direction of mainstream smoke (or other aerosol) drawn though a smoking article in use. 
     The smoking article  10  of the example of  FIG. 1  comprises a source of smokable material, such as tobacco, attached to a filter arrangement which comprises a first filter section  12  and a second filter section  14 . The source of smokable material is in the form of a tobacco rod  11 , which is attached to the first filter section  12 . The second filter section  14  is located downstream of the first filter section  12  and tobacco rod  11 . A ventilation arrangement  17  provides a user controllable variable level of ventilation into the first filter section  12 , as described in more detail below. 
     The resistance to gaseous flow through the length of the second filter section is lower than the resistance to gaseous flow through the length of the first filter section; and the resistance to gaseous flow through the length of the filter arrangement remains substantially constant as the level of ventilation is varied. The reduced resistance of the second filter section  14  results in the first filter section  12  having a greater influence on the overall resistance to gaseous flow of the filter arrangement. As ventilation is increased into the second filter section  14 , a lower resistance path is created for flow through the filter arrangement, therefore significantly reducing the resistance to draw experienced by the consumer, when compared to lower levels of ventilation. The reduced resistance of the second filter section  14  when compared to the first filter section therefore enhances the change in the resistance to draw experience by the consumer as the ventilation is altered, providing the consumer with a greater sensory indication that the ventilation has been changed. 
     The smoking article  10  comprises a first part comprising the tobacco rod  11  and the first filter section  12 . The tobacco rod  11  and first filter section  12  are connected with a covering layer to affix the first filter section to the tobacco rod, which is formed of tipping paper. The tobacco rod  11  and first filter section  12  are referred to as a tobacco unit. The elongate tobacco rod  11  and first filter section  12  define a longitudinal axis of the smoking article. 
     A second part of the smoking article comprises the second filter section  14  and a sleeve  13  which is movable relative to the first part of the smoking article. The sleeve is in the form of a tube extending around the circumference of the tobacco rod  11  and/or first filter section  12 . The tube can be cylindrical. The sleeve  13  is formed of paper. The second filter section  14  is securely attached and fixed within the sleeve. The first and second filter sections  12 , 14  each comprise filtration material which is wrapped in a sheet material, which may be paper, e.g. plugwrap. The first and second filter sections form a filter arrangement. The first filter section  12  is upstream of the second filter section  14 . The second filter section  14  is at a mouth end of the sleeve  13 , adjacent to, and separate from, the first filter section  12 . Alternatively, the first and second filter sections are connected. 
     The tobacco rod  11  and attached first filter section  12  are described as connected by tipping paper (not shown). The tipping paper is a standard tipping paper, or a relatively thick recessed tipping paper, or a board type tipping paper. 
     The smoking article  10  is provided with the ventilation arrangement  17  configured to allow adjustment of a ventilation of the smoking article  10 . The ventilation arrangement  17  comprises one or more second ventilation area  15  on the sleeve  13 , upstream of the second filter section  14 . The smoking article further comprises one or more first ventilation area  16  around the first filter section  12 . For example, the one or more first ventilation area  16  is defined by a layer(s) of sheet material around the first filter section or around the filtration material of the first filter section. The ventilation arrangement  17  provides for ventilating air to enter into the first filter section. The terms “upstream” and “downstream” are relative to the direction of the passage of smoke along the longitudinal axis of the smoking article  10 , i.e. “downstream” indicates in a direction toward the mouth end of the smoking article  10 . 
     Ventilation areas  15 , 16  are formed as ventilation apertures or air permeable material. In some embodiments, when ventilation areas  15  on the sleeve  13  are exposed, air can flow into the body of the smoking article  10 . When second ventilation areas  15  on the sleeve  13  and the corresponding first ventilation areas  16  around the first filter section  12  are aligned, air can flow into the body of the smoking article  10 . Ventilation areas  15 , 16  are aligned by rotation of the first part of the smoking article relative to the second part. In particular, the ventilation is controlled by rotation of the sleeve  13  relative to the first filter section  12 . The ventilation arrangement  17  provides a selectable variable level of ventilation controlled by adjusting the overlap of the second ventilation area  15  with the first ventilation area  16 . The amount of ventilation depends on the effective ventilating area, which is determined by the area of the overlap of the first and second ventilation areas. The level of ventilation can be selected by selecting a position of the second part relative to the first part e.g. by rotation of the second part relative to the first part. Thus, the ventilation arrangement  17  provides for a variable size of effective ventilation area, providing a variable intake of air, substantially upstream of the second filter section. 
     The first filter section  12  and second filter section  14  are made of a known filtration material. The filtration material for both filter sections can be tow, for example, cellulose acetate tow. The filtration material of the first filter section is homogenous, and independently, the filtration material of the second filter section is homogenous. The term “homogenous” is used to mean that the filtration material is substantially uniform throughout each filter section, and in particular, is uniform in a longitudinal and/or radial direction through each of the first and second filter sections  12 , 14 . At least one physical property of the homogenous first filter section is different to the homogenous second filter section. 
     The first filter section  12  provides a first resistance to gaseous flow through the length thereof. The resistance to gaseous flow through the length of the first filter section is determined by the filtration material of the first filter section. The resistance to gaseous flow indicates the pressure required to draw smoke through the length of the first filter section  12  at a particular rate. The term “pressure drop” can be used in place of “resistance to gaseous flow”. Pressure drop can be given in units of distance height of water (mmH 2 O). The first filter section has a first pressure drop per unit length, or resistance to gaseous flow per unit length, which is constant in a longitudinal direction through the first filter section  12 . Pressure drop per unit length is given per millimetre, i.e. in units of mmH 2 O/mm. The first pressure drop per unit length is determined by the filtration material of the first filter section. 
     The second filter section  14  provides a second resistance to gaseous flow through the length thereof. The resistance to gaseous flow through the length of the second filter section is determined by the filtration material of the second filter section  14 . The resistance to gaseous flow through the length of the second filter section  14  defines a second pressure drop. The second pressure drop or resistance to gaseous flow indicates the pressure required to draw smoke through the length of the second filter section  14  at a particular rate. The second resistance to gaseous flow (or pressure drop) per unit length is substantially constant in a longitudinal direction through the second filter section  14 . The second filter section  14  can be considered as comprising a filtration material having a second pressure drop per unit length. 
     In aspects of the present invention, the resistance to gaseous flow through the length of the first filter section  12  is greater than the resistance to gaseous flow through the length of the second filter section  14 . In another aspect, the tow weight of the second filter section  14  is lower than the tow weight of the first filter section  12 . The second density provided by the second filter section  14  is lower than the first density provided by the first filter section  12 . Optionally, the first pressure drop across the first filter section  12  is greater than the second pressure drop across the second filter section  14 . 
     The one or more ventilation areas  15 , 16  allowing selectable ventilation are upstream of the second filter section  14 . The relatively low resistance to draw through the length of the filter arrangement downstream of the ventilation area  15  provides an increased variation in an overall resistance to draw from the mouth end of the smoking article  10 , as ventilation is varied. 
     The ventilation arrangement  17  is located substantially upstream of the second filter section  14 . Ventilation of a smoking article  10  reduces the resistance to draw from the mouth end of the smoking article  10 . The ingress of ventilating air reduces the volume of air drawn through the length of smoking article  10  upstream of the ventilation areas, reducing the volume of air which experiences the resistance to gaseous flow upstream of the ventilating areas. The ventilating air enters directly with substantially no resistance, so the overall resistance to draw is reduced. In particular, the ingress of air through the ventilation areas  15  reduces the effect of the resistance to gaseous flow through the section of the smoking article  10  upstream of the ventilation areas  15 . The effect of the resistance to gaseous flow through the smoking article  10  downstream of the ventilation areas  15  is unchanged by variations in ventilation. 
     The relatively low resistance to gaseous flow provided by the lower density of the second filter section  14  (relative to the first filter section  12 ) downstream of the ventilation areas  15  defines a minority of the resistance to gaseous flow through the full length of the filter arrangement. Alternatively, the second filter section  14  provides a relatively small contribution to the overall resistance to draw from the mouth end of the smoking article  10 . The contribution of the one or more sections upstream of the ventilation area  15  on the overall resistance to draw is greater by comparison. The ingress of air reduces the effect of the pressure drop or resistance to gaseous flow through the upstream section only, and the downstream section with a lower resistance to gaseous flow or pressure drop is unaffected by the ventilation. Therefore, a relatively large proportion of the overall resistance to draw from the mouth end of the smoking article  10  is affected by the change in ventilation of the smoking article  10 . The decreased density of the second filter section  14  downstream of the ventilation areas  15  increases the proportion of the resistance to draw which is affected by the change in ventilation of the smoking article  10 . The decreased density of the second filter section  15  provides an increase in the effect of an increased ventilation on the overall resistance to draw from the mouth end of the smoking article  10 . 
     As the level of ventilation is varied, the resistance to draw from the mouth end of the smoking article  10  also changes. As the amount of ventilating air entering the smoking article  10  increases, the overall resistance to draw decreases. The relatively low pressure drop or resistance to gaseous flow through the second filter section  14  (e.g. achieved with a relatively low density of filter material) provides a relatively large change in overall resistance to draw caused by an increased level of ventilation. Therefore, as the level of ventilation is varied over a range selectable by the user, the resistance to draw from the mouth end of the smoking article  10  varies over a relatively large range as a result of the lower density of the second filter section  14 . Thus, the variation in resistance to draw from the mouth end of the smoking article is accentuated as the ventilation is varied. This can give the user a greater sensory indication that the ventilation level has been varied. 
     In some examples of the invention, the second filter section has a pressure drop per unit length of less than 5 mmH 2 O/mm. Alternatively, the second filter section has a pressure drop per unit length of less than a value selected from: 4 mmH 2 O/mm, 3 mmH 2 O/mm, 2 mmH 2 O/mm, 1.5 mmH 2 O/mm, and 1 mmH 2 O/mm. 
     In some examples of the invention, the first filter section has a pressure drop per unit length of more than 5 mmH 2 O/mm. Alternatively, the first filter section has a pressure drop per unit length of more than a value selected from: 6 mmH 2 O/mm, 7 mmH 2 O/mm, 8 mmH 2 O/mm, 9 mmH 2 O/mm, 10 mmH 2 O/mm, 11 mmH 2 O/mm, and 12 mmH 2 O/mm. 
     In some aspects, the pressure drop per unit length of the second filter section is between 1 and 5 mmH 2 O/mm, and the pressure drop per unit length of the first filter section is between 5 and 15 mmH 2 O/mm. In some examples, the pressure drop per unit length of the second filter section is less than 5 mmH 2 O/mm, and the pressure drop per unit length of the first filter section is more than 5 mmH 2 O/mm. The upstream filter section has a pressure drop per unit length which is higher than a pressure drop per unit length of the downstream filter section. The upstream filter section has a pressure drop per unit length which is higher than any of the example values specified, and a pressure drop per unit length of the downstream filter section is lower than any of the example values specified. 
     In some examples, the resistance to gaseous flow through the length of the second filter section is lower than the first filter section by at least a multiple value selected from one of: 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 and 15. 
     For example, the resistance to gaseous flow through the length of the second filter section is between 2 and 15 times lower than through the length of the first filter section. Optionally, the second pressure drop per unit length of the second filter section is between 5 and 12 times lower than the first pressure drop per unit length of the first filter section. 
     In some aspects, the ventilation arrangement  17  is located at a downstream end of the first filter section  12 . In some examples, the ventilation arrangement is located less than 10 mm from the downstream end of the first filter section  12 . 
     The pressure drop per unit length of the first and second filter sections is determined (at least partially) by the physical structure of the filtration material forming the filter sections. The first and second filter sections can both comprise fibrous material, comprising tow filaments. For a filtration material comprising tow filaments, the pressure drop per unit length can be determined by the amount or number of tow filaments in a particular volume or length. The tow weight is a measure of the amount of tow fibres in a certain volume. The pressure drop per unit length can also be determined by the cross-section of the tow filaments. For example, the tow filaments can have an X-shaped cross-section or a Y-shaped cross-section. The cross-sectional area can also affect the pressure drop per unit length. The tow weight can provides an indication of the density of a fibrous material within the filter section. The pressure drop per unit length can also be determined by the amount or degree of crimping (i.e. folding) of the filaments, during the manufacturing processes. These factors affecting the pressure drop per unit length of the filter sections are known, and can be selected to obtain the required pressure drop per unit length for each of the first and second filter sections individually. Thus, the first and second filter sections comprise filtration material which has a physical property determined by a different selection of any one or more of the above characteristics. The first and second filter sections are manufactured using filtration material formed or treated to have the required properties, for example as above, providing the different pressure drop per unit length for the first and second filter sections. 
       FIG. 2  is a perspective view of the part of the smoking article  10  illustrated in  FIG. 1 . As illustrated in  FIG. 2 , the tobacco rod  11  and first filter section  12  are dimensioned to rotate as a unit around a longitudinal axis within the sleeve  13 . A restraining means (not shown) retains the first part and second part in a fixed longitudinal arrangement, and prevents extension of the smoking article  10 . Thus, the first part cannot slide longitudinally relative to the second part, i.e. the sleeve is not movable longitudinally relative to the tobacco unit. 
     The level of ventilation can be selected by selecting an angular position of the sleeve  13  relative to the first filter section  12 . 
     In some examples, the ventilation areas  15  are configured to increase in size non-linearly with respect to angular position. The ventilation areas  15  are configured such that the level of ventilation has a substantially linear dependence on the angular position of the sleeve  13  relative to the first filter section  12 . 
     In some aspects, the one or more ventilation areas  15  maintain a fixed longitudinal position relative to the first and second filter sections, when the sleeve  13  is rotated relative to the first filter section  12 . 
     In the present embodiment, the second filter section  14  is securely attached and fixed within the sleeve  13 . Rotation of the second filter section  14  causes a corresponding rotation of the sleeve  13  relative the first filter section  12 . 
     By selecting a different angular position of the second filter section  14  relative to the first filter section  12 , the registry between the ventilation areas  15  in the sleeve  13  and the ventilation areas  16  in the sheet material or plugwrap around the first filter section  12  can be selectively increased or decreased. The level of ventilation in the smoking article  10  can therefore be increased or decreased. 
       FIG. 3  is a longitudinal cross-sectional view of a part of a smoking article according to a second embodiment of the invention. The overall layout is similar to the example of  FIGS. 1 and 2  described above, the same parts having the same reference numerals, and parts other than those described remaining unchanged. 
     In the embodiment of  FIG. 3 , the second filter section  24  is formed to have an air passage  28  passing longitudinally through its centre. The second filter section  24  and air passage  28  form a tubular filter section extending along the longitudinal axis of the smoking article  20 . The second filter section  24  is formed from fibrous filtration material having an annular cross-section. Alternatively, the air passage  28  may pass longitudinally along a non-central path through the second filter section. Optionally, the second filter section may be formed to have a plurality of air passages which pass longitudinally therethrough. 
     The air passage  28  reduces the resistance to gaseous flow through the length of the second filter section  24 . The resistance to gaseous flow through the length of the second filter section  24  is lower than the resistance to gaseous flow through the length of the first filter section  12 . 
     The dimensions of the second filter section  24  will depend on various factors such as the desired resistance to draw or the second filter section  24  relative to the first filter section  12 , the properties of the filter tow and the level of plasticiser, such as triacetin, added to the filter tow. However, in examples herein, the outer circumference of the second filter section is between 15 and 25 mm, for instance between 22 mm and 25 mm, or 23.95 mm. The internal diameter of the air passage  28  is preferably between 1 mm and 7 mm, for instance between 3 mm and 6 mm, or 4.8 mm. 
       FIG. 4  is a perspective view of the smoking article illustrated in  FIG. 3 . As illustrated in  FIG. 4 , the air passage  28  is located to pass longitudinally through the centre of the second filter section  24 . Alternatively, the air passage  28  may pass longitudinally along a non-central path through the second filter section  24 . Optionally, the second filter section  24  may be formed to have a plurality of air passages which pass longitudinally therethrough. 
     EXAMPLE 
     Table 1 below illustrates calculated values for the resistance to draw from the mouth end of a conventional “Smoking Article 1” compared with calculated values for the resistance to draw from the mouth end of an example “Smoking Article 2”, according to an example of the invention. Each smoking article has a filter with total length 27 mm, and variable ventilation system allowing ingress of air at a distance 16.5 mm from the mouth end of the filter. The filter is formed of the first and second filter sections which are axially aligned. The mouth end filter section (second filter section) is 8 mm long, and the tobacco end filter section (first filter section) is 19 mm long. Both smoking articles have an identical tobacco rod with a resistance to draw (pressure drop) of 43.43 mm H 2 O. 
     The conventional filter of Smoking Article 1 has a provides a substantially uniform pressure drop per unit length of approximately 5 mmH 2 O/mm, for both first and second filter sections. The pressure drop is 85 mmH 2 O for the first filter section with a length of 19 mm, and a pressure drop of 40 mmH 2 O for the second filter section with a length of 8 mm. 
     In the example of Smoking Article 2, according to the invention, the second filter section is an 8 mm filter section at the mouth end of the filter, which has a pressure drop of 8 mmH 2 O. This provides a relatively low pressure drop per unit length of 1 mmH 2 O/mm. The upstream first filter section has a length of 19 mm adjacent the tobacco rod, and has a relatively high pressure drop per unit length. This provides a pressure drop per unit length of 7.11 mmH 2 O/mm. 
     
       
         
           
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                 Smoking Article 1 
                 Smoking Article  
               
               
                   
                 (example conventional 
                 2 (example 
               
               
                   
                 smoking article) 
                 of invention) 
               
               
                   
                 Pressure  
                 Pressure  
               
               
                   
                 drop (mmH 2 O) 
                 drop (mmH 2 O) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 First filter section (19 mm) 
                 85 
                 135 
               
               
                 PD 
                   
                   
               
               
                 Second filter section (8 mm) 
                 40 
                 8 
               
               
                 PD 
                   
                   
               
               
                 PD of filter downstream of 
                 78.03 
                 68.39 
               
               
                 vent 
                   
                   
               
               
                 PD of filter upstream of vent 
                 46.97 
                 74.61 
               
               
                 PD Tobacco Rod 
                 43.43 
                 43.43 
               
               
                 Total PD at 40% ventilation 
                 132.27 
                 139.22 
               
               
                 Total PD at 60% ventilation 
                 114.19 
                 114.61 
               
               
                 Total PD at 80% ventilation 
                 96.11 
                 92.00 
               
               
                   
               
            
           
         
       
     
     The pressure drop through the full smoking article (including tobacco rod) is determined for ventilation values with a level of ventilation between 40% and 80% ventilated. For the conventional Smoking Article 1 the pressure drop varies from 132.27 to 96.11 mmH 2 O ventilation as ventilation increases. However, in the Smoking Article 2, according to the invention, the pressure drop varies from 139.22 mmH 2 O to 92 mmH 2 O over the same ventilation range. Thus, the drop of 47.22 mm H 2 O provided by the invention, compared with only 36.16 mm H 2 O for the conventional smoking article, provides an increase change in pressure drop (i.e. more varied resistance to draw from the mouth end) when varying the ventilation of the smoking article. These results are illustrated in  FIG. 5 , in which the y-axis indicates pressure drop and the x-axis indicated the percentage ventilation. 
     In some embodiments, the pressure drop downstream of the ventilation arrangement  17  is decreased further by reducing the distance between the mouth end of the smoking article and the one or more ventilation areas. 
     In some examples of the invention, the ventilation areas allow the ingress of air at a distance from the mouth end which is less than 15 mm. Alternatively, the distance from the mouth end of the ventilation are is less than a value selected from: 14 mm, 13 mm, 12 mm, 11 mm, and 10 mm. 
       FIG. 6 a    is a plan view of a blank  30  forming a wrapper for a smoking article according to a third embodiment of the invention.  FIG. 6 b    is a plan view of a rod article  32  to which the blank  30  of  FIG. 6 a    is applied to form the smoking article. The smoking article comprising the blank  30  has substantially the same functions as described above. Features have the same arrangement and function unless otherwise described. 
     The blank  30  is configured to wrap twice only around the whole circumference of the rod article  32 . The blank  30  is configured to define two complete layers extending around the circumference of the rod article  32 , and comprises areas to define an inner layer and an outer layer. 
     The blank  30  comprises a control element  34  movable in a channel  36 , configured to control ventilation and limit movement. 
     The control element  34  is movable circumferentially within a limited range. The control element  34  is movable between a first engaging surface and a second engaging surface. The first engaging surface and second engaging surface define a circumferentially extending channel  36  in which the control element  34  is movable. 
     The control element  34  defines first and second limiting surfaces  34   a,    34   b  at the edges of the control element in the direction of movement, i.e. at the circumferential edge of the control element  34 . Contact of the first and second limiting surfaces  34   a,    34   b  of the control element  34  between the first engaging surface and the second engaging surface limits relative rotation between the first and second parts of the smoking article. 
     The first and second limiting surfaces  34   a,    34   b  extend at an angle to a longitudinal axis of the smoking article. The first and second engaging surfaces also extend at an angle to the longitudinal axis of the smoking article, and/or at an angle to the axis of movement of the control element. The first and second engaging surfaces extend at the same angle and/or have a complementary shape to the first and second limiting surfaces  34   a,    34   b.    
     The blank  30  comprises the first and second spacing sections  38   a,    38   b.  The first and second spacing sections  38   a,    38   b  are configured to directly attach to and circumscribe the rod articles. The first and second spacing sections  38   a,    38   b  have the function of spacing a plurality of optional indexing surfaces at a correct radial distance to allow indexing. The first and second spacing sections  38   a,    38   b  are longitudinally spaced apart. 
     The control element  34  is configured to directly overlie one of the spacing sections  38   a,    38   b.  The control element is movable over the spacing section  38   a,  the spacing section providing a substantially smooth exterior surface over which the control element is easily moved. 
     Referring to  FIG. 6 b   , the rod article  32  includes a tobacco rod  11 , similar to those previously described, and first and second filter sections  40 ,  42  downstream of the tobacco rod  11 . The second filter section  42  is provided, as a tubular section substantially similar to the second filter section  24  described in relation to the second embodiment, downstream of the first filter section  41  and tobacco rod  11 , at the mouth end of the smoking article. The first filter section  40  is provided between the second filter section  42  and the tobacco rod  11 . When the blank  30  is wrapped around the rod article  32 , the control element  34  is spaced by the spacing section from the first filter section  40 . The first filter section  40  optionally defines a first indexing surface  40   a,  and so does not provide a smooth surface for the control element. 
     The first and second spacing sections  38   a,    38   b  are optionally connected by a spacer connection  44 . The first and second spacing sections  38   a,    38   b  extend circumferentially over the two layers of the first blank  30 . The spacer connection  44  is adjacent a leading edge of the first blank  30 , i.e. the point on the blank  30  first wrapped around the rod article  32 . 
     The spacer connection  44  and longitudinally adjacent areas of the spacing sections  38   a ,  38   b  are initially affixed to the rod article to begin wrapping of the first blank  30 , for example, with adhesive. The spacer connection  44  provides for the blank  30  to have a single initial area of attachment to the rod article  32 . The spacing sections  38   a,    38   b  are not affixed as independent elongate sections of sheet material, requiring separate attachment to the rod article  32 . Thus, the connection of the leading edges of the spacing sections  38   a,    38   b  improves initial attachment of the blank  30  to the rod articles. 
     The spacer connection  44  has a trailing edge  44   a  at a circumferentially opposite end of the spacer connection  44  to the leading edge. The spacer connection trailing edge  44   a  extends between the first and second spacing sections  38   a,    38   b.  The spacer connection trailing edge  44   a  extends at an angle to a longitudinal axis of the smoking article. 
     The control element  34  is formed on a support section  46  of the blank  1401 . The control element  34  defines the longitudinally extreme area of the section to which the control element is attached. Thus, the first and second limiting surfaces  34   a,    34   b  of the control element  34  extend longitudinally beyond the section to which the control element is attached. The support section  44  is attached to the first and second spacing sections with frangible connections. The frangible connections are circumferentially extending line of perforations. The support section  46  extends one time around the whole circumference of the smoking article, e.g. to form a tube. The control element is curved as a part of that tube. 
     The support section  46 , optionally supports a second indexing surface  48 . In particular, the second indexing surface optionally comprises a pawl  48  formed on a pawl support unit  50 , which is attached to the support section  46 . The pawl  48  is configured to extend between the first and second spacing sections  38   a,    38   b,  and engage with the optional first indexing surface  40   a.    
     The support section  46  comprises a support section leading edge  46   a.  The support section leading edge  46   a  defines the initial point of the support section  46  which is first wrapped around the rod article  32 . The support section leading edge  46   a  extends at an angle to a longitudinal axis of the smoking article. 
       30  A trailing edge  46   b  of the support section  46  extends substantially parallel to the longitudinal axis of the smoking article. 
     The spacer connection trailing edge  44   a,  support section leading edge  46   a  and first and second spacing sections  38   a,    38   b  define an aperture  52  in the blank  30 . The aperture  52  provides a space in which the support section  46  is movable. 
     In some examples, the aperture  52  has a circumferential extent which is greater than a circumferential extent of movement of the control element  34 . Thus, the spacer connection trailing edge  44   a  does not determine the range of movement of the control element  34 . 
     The area of blank  30  forming the inner layer, e.g. on the first spacing section  38   a , comprises a ventilation area  54 . In some examples, the ventilation area  54  comprises a single aperture. Alternatively, the ventilation area  54  comprises a plurality of discrete permeable areas or apertures. For example, the apertures are formed by electroperforation (EP). 
     The control element  34  has a further function in controlling the ventilation of the smoking article. In particular, the control element  34  directly controls the ventilation of the smoking article by selectively covering one or more ventilation areas. The control element  34  is configured to be movable over one or more ventilation areas in a radially adjacent, and integrally formed, part of the smoking article. The control element  34  is formed of a material which is substantially impermeable to air, in particular, paper which is not permeable to air. The control element  34  is configured to cover the one or more ventilation areas of the smoking article, such that ventilation air cannot enter the smoking article through an area which is covered by the control element  34 . The control element is impermeable to air between the first and second limiting surfaces  34   a,    34   b.  The first and second limiting surfaces  34   a,    34   b  define both the limits of rotation and define the amount of ventilation area which is covered or uncovered. 
     Thus, the control element  34  has the dual function of both directly controlling a level of ventilation by covering a part of a ventilation area and limiting relative movement of the first and second parts of the smoking article between maximum and minimum levels of ventilation. 
     In some aspects, the smoking article comprises a further ventilation area  56 . For example, the first filter section  40  comprises the further ventilation area  56 . The ventilation area  54  is arranged to at least partially coincide with the further ventilation area  56 . The further ventilation area  56  comprises a plurality of discrete ventilation areas or apertures, for example, in a circumferentially extending line. The further ventilation area  56  can be formed by a laser. Generally, one or more of the ventilation areas  54 ,  56  comprise a plurality of discrete ventilation areas or apertures. 
       FIG. 7 a    is a plan view of a blank  60  forming a wrapper for a smoking article according to a fourth embodiment.  FIG. 7 b    is longitudinal cross-sectional view of a smoking article  62  to which the blank  60  of  FIG. 7 a    has been applied. The smoking article  62  comprising the blank  60  has substantially the same functions as described above. Features have the same arrangement and function unless otherwise described. 
     Referring to  FIG. 7   b,  the rod article  62  includes a tobacco rod  11 , similar to that previously described, and first and second filter sections  12 ,  14  downstream of the tobacco rod  11 . The second filter section  14  is provided downstream of the first filter section  12  and tobacco rod  11 , at the mouth end of the smoking article. The first filter section  12  is provided between the second filter section  14  and the tobacco rod  11 . The first filter section  12  is divided into a first part  12 ′ and a second part  12 ″ by a cut  12 ′″, allowing the first part  12 ′ of the first filter section  12  to move relative to the second part  12 ″. 
     The blank  60  is configured to wrap twice, and in the present example twice only, around the whole circumference of the rod article  62 . The blank  60  has a first section  60   a  which first wraps around the rod article  62  forming an inner layer and a second section  60   b  which then wraps around the first section  60   a,  forming an outer layer. The blank  60  is therefore configured to define two complete layers extending around the circumference of the rod article  62 , and comprises areas  60   a,    60   b  to define an inner layer and an outer layer. 
     The first section  60   a  of the blank  60  comprises a first end portion  60   a ′ connected to the second filter section  14  and to the first part  12 ′ of the first filter section  12 , and therefore connecting the second filter section  14  and the first part  12 ′ of the first filter section  12  together. The first section  60   a  of the blank  60  also comprises a second end portion  60   a ″ connected to the second part  12 ″ of the first filter section  12 . The second section  60   b  of the blank  60  is separated into a first part  60   b ′ and a second part  60   b ″ by a cut  61 . 
     The blank  60  comprises, on the first section  60   a,  a control element  64  movable in a circumferentially extending channel  66 , configured to control ventilation and limit movement. 
     The control element  64  is movable circumferentially within a limited range. The control element  64  is movable between a first engaging surface and a second engaging surface. The first engaging surface and second engaging surface define the circumferentially extending channel  66  in which the control element  64  is movable. 
     The control element  64  defines first and second limiting surfaces  64   a,    64   b  at the edges of the control element in the direction of movement, i.e. at the circumferential edge of the control element  64 . Contact of the first and second limiting surfaces  64   a,    64   b  of the control element  64  with the first engaging surface and the second engaging surface of the circumferentially extending channel  66  limits relative rotation between the first and second parts of the smoking article. 
     The first and second limiting surfaces  64   a,    64   b  extend at an angle to a longitudinal axis of the smoking article. The first and second engaging surfaces also extend at an angle to the longitudinal axis of the smoking article, and/or at an angle to the axis of movement of the control element. The first and second engaging surfaces extend at the same angle and/or have a complementary shape to the first and second limiting surfaces  64   a,    64   b.    
     A longitudinal movement restricting arrangement  65  comprises a sliding element  67  which is arranged to move between first and second restricting elements  68   a  and  68   b . Sliding element  67  is attached to first and second restricting elements  68   a  and  68   b  with a frangible connection. The frangible connection is a circumferentially extending line of perforations. The part of the blank including the sliding element  67 , control element  64 , first and second restricting elements  68   a  and  68   b  and circumferentially extending channel  66  extends one time around the whole circumference of the smoking article, e.g. to form a tube. The sliding element  67  is attached to first part  60   b ′ of the second section  60   b  of the blank  60 , together with the first part  60   a ′ of the first section  60   a  of the blank, and therefore moves, together with the first part  60   a ′ of the first section  60   a , the second filter section  14  and the first part  12 ′ of the first filter section  12 , relative to  30  the second part  60   a ″ of the first section  60   a  of the blank  60  and the second part  12 ″ of the first filter section  12 . 
     The second section  60   b  of the blank  60  forming the outer layer, comprises a ventilation area  69 ′ at a location  69  on the blank. In some examples, the ventilation area  69 ′ comprises a single aperture. Alternatively, the ventilation area  69 ′ comprises a plurality of discrete permeable areas or apertures. For example, the apertures are formed by electroperforation (EP). The ventilation area  69 ′ is arranged to align with the channel  66  when the blank  60  is wrapped around the rod article  62 . 
     The control element  64  has a further function in controlling the ventilation of the smoking article. In particular, the control element  64  directly controls the ventilation of the smoking article by selectively blocking one or more ventilation areas. The control element  64  is configured to be movable relative to one or more ventilation areas in a radially adjacent, and integrally formed, part of the smoking article. The control element  64  is formed of a material which is substantially impermeable to air, in particular, paper which is not permeable to air. The control element  64  is configured to move between the ventilation area  69 ′ and the underlying rod article  62  of the smoking article, such that ventilation air cannot enter the smoking article through the channel  66  which is blocked by the control element  64 . The control element is impermeable to air between the first and second limiting surfaces  64   a,    64   b.  The first and second limiting surfaces  64   a,    64   b  define both the limits of rotation and define the amount of ventilation area which is covered or uncovered. 
     Thus, the control element  64  has the dual function of both directly controlling a level of ventilation by covering a part of a ventilation area and limiting relative movement of the first and second parts of the smoking article between maximum and minimum levels of ventilation. 
     In some embodiments, the first filter section  12  comprises flavourant in the form of botanical particles. However, the first filter section  12  can comprise other forms of flavourant, such as one or more capsules, a thread loaded with flavourant, flavourant dispersed in filter tow, flavour impregnated particles or a sheet material comprising a flavourant, which lie upstream of the ventilation area  69 ′. The level of ventilation in the smoking article  10  controls the dilution of smoke which passes through the first part of the smoking article  10  with air which enters the smoking article  10  through the ventilation area  69 ′. Therefore the level of ventilation also controls the dilution of flavoured smoke which has passed through the flavourant with unflavoured air which enters the smoking article through the ventilation area  69 ′. The level of flavour in the smoking article can therefore be increased or decreased. 
     In some aspects, the blank  60  comprises a further ventilation area (not shown) at a location  63  on the blank downstream of the variable ventilation arrangement  69 ′. The further ventilation area comprises a plurality of discrete ventilation areas or apertures, for example, in a circumferentially extending line. The further ventilation area can be formed by a laser. Generally, one or more of the ventilation areas comprise a plurality of discrete ventilation areas or apertures. The further ventilation area provides a constant minimum level of ventilation which is unaffected by the variable amount of ventilation from the ventilation area  69 ′. The amount of ventilation provided by the further ventilation area can be predetermined in the manufacture of the smoking article  10  and is, for instance, between 5% to 50% of the volume of smoke and/or other aerosol generated by said smoking article passing through the filter section when said variable ventilation is at its minimum level. The variable ventilation arrangement  69 ′,  66  can be arranged to provide ventilation which is user controllable within a sub-range within the range of from 0% to 90% of the volume of smoke and/or other aerosol generated by said smoking article passing through the filter section, for instance from 0% to 50% ventilation. 
       FIG. 8  illustrates schematically a method  100  of manufacturing smoking articles according to the invention. The method  100  comprises forming a first filter section with a first resistance to gaseous flow or pressure drop (step  110 ). The first filter section is formed from a known filtration material, for example, cellulose acetate tow. A second filter section is separately produced (step  120 ). The second filter section is also formed from cellulose acetate tow. The resistance to gaseous flow through the length of the second filter section is lower than the resistance to draw through the length of the first filter section. Optionally, the pressure drop of the second filter section is lower than the pressure drop of the first filter section. 
     The different pressure drop properties of the first and second filter sections are determined during manufacturing of the first and second filter sections. In some aspects, the fibrous filtration material, i.e. tow elements are configured differently for the first and second filter sections. For example, the second filter section is formed with a different diameter tow, compressed more than the first filter section, different cross-section, to obtain the different properties (i.e. lower density). The pressure drop properties of the first and second filter sections are not substantially changed or modified during use of the smoking article. 
     In an embodiment, the second filter section is formed with an annular cross section, to obtain a lower density. The first and second filter sections is formed from the same fibrous filtration material, and formed to have different cross sections in order to obtain the different properties. In some examples, the filter arrangement is formed of a single piece including the first filter section and the second filter section. 
     The first filter section and second filter section are assembled with one or more additional components to form the filter arrangement of the smoking article (step  130 ). The first and second filter sections may be longitudinally aligned with a source of smokeable material. Any other known filter components can be added to the smoking article. Examples of further filter components include a third filter section, for instance a filter section with particulate material (e.g. carbon, activated charcoal) or an additional hollow section. The first and/or second filter sections can each be considered as comprising one or more discrete filter sections. The filter sections can be considered as generally upstream and downstream of the variable ventilation area. The one or more upstream filter section has a higher resistance to gaseous flow than the one or more downstream filter section. 
     Wrapping material is applied to the smoking article assembly to attach the component parts. The paper wrapping material is tipping paper. In addition, a sleeve is wrapped around the smoking article. The sleeve is configured to move relative to the first filter section and, optionally, is securely attached to the second filter section. 
     The smoking article is configured to allow the ingress of a selectively variable amount of air upstream of the second filter section. For example, ventilation apertures are formed in the outermost layer of paper wrap and/or the paper sleeve. The ventilation apertures are formed by a mechanical cutting tool or a laser. The ventilation apertures are formed in the wrapping material prior to the assembly of the smoking article (i.e. pre-perforated apertures) or, optionally, when the smoking article is assembled. 
     The ventilation has been described by entering the smoking article upstream of the second filter section, and in particular, into the first filter section. Alternatively, the ventilation can be at least partially into the second filter section, e.g. adjacent an upstream end of the second filter section. A ventilating position for ingress of air which includes both upstream of the second filter section and optionally an upstream part (e.g. upstream quarter) of the second filter section is termed as located substantially upstream of the second filter section. 
     The properties of the filter sections can be defined in terms of any of: pressure drop per unit length, resistance to gaseous flow per unit length, pressure drop, resistance to gaseous flow, tow weight, or density. The filter sections can be defined in terms of the filtration material having a resistance to gaseous flow, which can be considered as independent of the length of the filter section. 
     The smoking article can comprise one or more ventilation areas providing a base level of ventilation. Such ventilation areas (not shown) are not variable in size. 
     In order to address various issues and advance the art, the entirety of this disclosure illustrates by way of illustration various embodiments in which the claimed invention(s) may be practiced and provide for a superior smoking article. The advantages and features of the disclosure are of a representative sample of embodiments only, and are not exhaustive and/or exclusive. They are presented only to assist in understanding and teach the claimed features. It is to be understood that advantages, embodiments, examples, functions, features, structures, and/or other aspects of the disclosure are not to be considered limitations on the disclosure as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the scope and/or spirit of the disclosure. Various embodiments may suitably comprise, consist of, or consist essentially of, various combinations of the disclosed elements, components, features, parts, steps, means, etc. In addition, the disclosure includes other inventions not presently claimed, but which may be claimed in future.