Abstract:
The present invention relates to a method for making smoking articles, smoking articles, and more particularly to a method for manufacturing smoking articles having a reduced ignition propensity. A method of manufacturing a smoking article includes the steps of providing a filter element ( 40 ) and at least one rod ( 30 ) of smokeable material surrounded by a wrapper, wrapping a section of tipping paper ( 12 A) around the filter element and a portion of the at least one wrapped rod and applying one or more patches ( 12 B 1, 12 B 2 ) of material to the outer surface of the wrapper. The patches can be arranged to reduce the ignition propensity of the smoking article and are applied to the outside of the wrapper, such that this can occur online during manufacture of the wrapped rod.

Description:
FIELD OF INVENTION  
       [0001]    The present invention relates to a method for making smoking articles, smoking articles, and more particularly to a method for manufacturing smoking articles having a reduced ignition propensity. 
       BACKGROUND TO THE INVENTION  
       [0002]    Many different methods have been suggested for manufacturing smoking articles such as cigarettes having a reduced ignition propensity i.e. a tendency to self-extinguish when not drawn on by a smoker. Such smoking articles are generally referred to as having a low ignition propensity (LIP). It has been recognised that the constitution of the wrapper has a significant effect on the burn rate of a cigarette and by modifying the wrapper by various methods, a self-extinguishing cigarette can be produced. 
         [0003]    One method for making wrappers for smoking articles having reduced ignition propensity is to add bands of paper to the wrapping paper, wherein the composition of the wrapper and the band paper are selected to yield a composite paper having the desired burn rate, as disclosed in EP 0 483998 and EP 0 262550. The bands are typically applied to the paper before it is wrapped around a tobacco core, and when the paper is wrapped around the tobacco the bands are on the inside of the paper, facing the tobacco. When the paper is used to manufacture the cigarettes, the bands are randomly situated along the length of the cigarette. 
         [0004]    To ensure that cigarettes meet the requirements for self-extinguishment which exist in various counties, the accurate positioning of the bands along the length of the cigarette can be important. However, when using banded papers, ensuring that the bands are positioned in the correct positions along the cigarette is not straightforward and requires longitudinal registration of the paper, adding complexity to the cigarette manufacturing machinery. 
         [0005]    Another method for making smoking articles having reduced ignition propensity is to apply a burn retardant additive to the smoking article wrapper, for instance cigarette paper. The burn retardant additive is typically applied as a solution in a pattern such as bands which, in the final assembled cigarette, extend around the circumference of the cigarette. A method for manufacturing a suitable such banded paper is disclosed in W 098/01233. 
         [0006]    Attempts have been made to apply burn retardant additive banding during the cigarette making process. This allows the bands to be positioned at desired locations by synchronising the application of the bands with cutting of the rod formed when the tobacco is wrapped in the banded paper. This overcomes the problem of positioning of the bands found with the pre-manufactured banded papers. This on line application of banding is disclosed in WO 2004/057986 and US 2004/0261805. However, these processes have additional drawbacks. One problem is in the drying of the paper once the burn retardant solution has been applied. Firstly, this must be dried before the garniture section of the machine where the tobacco is wrapped in the paper, because if the paper is damp at this stage when it comes into contact with the tobacco then discolouration of the paper may occur. Furthermore, the machines used for wrapping cigarettes, which may be modified to include a section for applying a burn retardant solution, apply significant tension to the paper and when the paper is damp its tensile strength is significantly reduced so that tearing of the paper easily occurs. Various heaters can be included in the machine to assist in drying the paper but to allow time for these to properly dry the paper, the machine must be slowed. The slowing of the machine may also alleviate problems with tearing, but this decreases production efficiency. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention provides a method of manufacturing a smoking article comprising providing a filter element and at least one rod of smokeable material surrounded by a wrapper, wrapping a section of tipping paper around the filter element and a portion of the at least one wrapped rod and applying one or more patches of material to the outer surface of the wrapper. 
         [0008]    The present invention also provides a smoking article comprising a rod of smokeable material surrounded by a wrapper, a filter element at one end of the wrapped rod, a tipping paper surrounding the filter element and a portion of the wrapped rod and a patch of material applied to the outer surface of the wrapper. 
         [0009]    Therefore, one or more patches are applied to the outside of the wrapper, such that this can occur online during manufacture of the wrapped rod. This allows the position of the patches relative to the filter in the final smoking article to be determined. 
         [0010]    The step of applying the one or more patches of material to the wrapper of the at least one wrapped rod can be performed in association with the step of wrapping the section of tipping paper around the filter element and an end of the at least one wrapped rod. In this way, modification to existing cigarette manufacturing processes in order to apply the additional patches can be minimised and production rates are not limited by the modification. 
         [0011]    The one or more patches can comprise a low porosity or non porous web material and/or can comprise a web material having a permeability of approximately 50 CU or less, preferably approximately 10 CU or less. The one or more patches can be bands applied around the full circumference of the at least one wrapped rod, and/or applied such that the mouth-end side of the band is within the 50% of the length of the rod which is closest to the filter element. 
         [0012]    The application of the bands can include applying a second band to each rod simultaneously to the application of the first band. The second band can be applied such that the mouth-end side of the second band is within the 50% of the length of the rod which is furthest from the filter element. 
         [0013]    The step of providing a filter element and at least one rod of smokeable material surrounded by a wrapper can comprise providing first and second rods of smokeable material surrounded by wrappers, and a filter element interposed between the first and second rods, and the method can further comprise cutting the filter element to form two smoking articles after application of the one or more patches. 
         [0014]    The method can also comprise splitting tipping paper from a roll to form both the patches and the section to be applied to the filter element and the ends of the wrapped rods. 
         [0015]    The one or more bands can be spaced from an edge of the tipping paper and/or have a width of at least 4 mm. The material for the patches can be the same as the tipping paper material, although additional printing may be used on the section of material used on the tipping paper or bands. 
         [0016]    The invention is defined in the claims appended hereto. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    Preferred embodiments of the present invention will now be described with reference to the accompanying drawings, in which: 
           [0018]      FIG. 1  is a schematic illustration of a method of manufacturing a smoking article according to an embodiment of the present invention; 
           [0019]      FIG. 2  shows a smoking article according to an embodiment of the present invention; 
           [0020]      FIG. 3  shows a smoking article in which a window in a patch exposes a region of underlying wrapper; 
           [0021]      FIG. 4  shows another smoking article in which a window in a patch exposes a region of underlying wrapper. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]      FIG. 1  illustrates a method and apparatus for manufacturing smoking articles in the form of cigarettes, according to an embodiment of the invention. 
         [0023]    In accordance with standard cigarette manufacturing processes, a continuous wrapped rod of tobacco  20  is supplied from a garniture region of a cigarette making machine to cutting means  21 A and  21 B which cut the rod  20  into lengths required for a single cigarette. The first cutting means  21 A cuts the rod  20  into double length rods, each having a length required to make two cigarettes, and then second cutting means  21 B cuts the double length rods into single length rods  30 . Each pair of single length rods  30  is separated and a double length filter  40  is positioned between the ends of the two wrapped rods  30  such that each end of the double length filter  40  abuts an end of one of the single length rods  30 . 
         [0024]    Tipping paper is supplied from a reel  13  of tipping paper mounted on a bobbin. In  FIG. 1 , the tipping paper is split longitudinally into three sections, comprising a wider central section  12 A and two narrower edge sections  12 B 1 ,  12 B 2  and adhesive  14  is applied to the tipping paper. Alternatively, the adhesive could be applied before splitting with dry lines provided on the gummer roller positioned to allow a clean cut to take place after application of adhesive. The sections  12 A,  12 B 1 ,  12 B 2  are then cut laterally into individual segments, each of which is applied to a double cigarette assembly. The wider central section  12 A is wrapped around the centre of the double cigarette assembly such that it covers the entire double length filter  40  and overlaps an end of each of the wrapped rods  30 . Thus the central section  12 A forms a tipping paper section  12 A which attaches the double length filter to the pair of wrapped rods  30 . Each of the edge sections  12 B 1 ,  12 B 2  comprises a patch which is wrapped around a respective one of the wrapped rods  30 , spaced from a respective edge of the central section  12 A to form a circumferential band. The patches  12 B 1 ,  12 B 2  may alternatively be applied so that they only partially circumscribe the wrapped rod  30 , thereby forming a partial band. 
         [0025]    The double length cigarette assembly is subsequently cut by third cutting means  50  at the centre of the double length filter  40  to form a cigarette pair. 
         [0026]    In the method illustrated in  FIG. 1 , the patch sections  12 B 1  and  12 B 2  form an LIP band on each wrapped rod  30  and are applied to the wrapped rods  30  online during cigarette manufacture, in a process step associated with the step of applying the tipping paper section  12 A to connect the filter to the wrapped rods  30 . For instance, the patch sections  12 B 1  and  12 B 2  can be applied simultaneously to applying the tipping paper section  12 A or can be otherwise applied in the same phase of manufacture as that in which the tipping paper section  12 A is applied, for instance after formation of the wrapped rods  30 . 
         [0027]    The cigarettes manufactured by the method illustrated in  FIG. 1  include only a single LIP patch spaced from an edge of the tipping paper. Preferably the patch is positioned in the first 50% of the exposed length (i.e. the 50% closest to the filter end) of the wrapped rod. This is because it is desirable that the cigarette self extinguish towards the end of the smoking. However, it may also be desirable to provide further patches at different positions along the wrapped rod to provide the cigarette with the potential to self extinguish at different points during smoking. To provide further patches, for one or more additional bands, a wider reel  13  of tipping paper may be provided, wherein the paper is split into further longitudinal ribbons. For example, if two bands are required, the paper may be split into five ribbons. 
         [0028]      FIG. 2  shows a smoking article in the form of a cigarette, in accordance with an embodiment of the present invention, having two LIP bands A, B. The cigarette comprises a wrapped rod  30  and a filter attached to the wrapped rod  30  by tipping paper  2  which covers the filter and overlaps the wrapped rod  30 . The wrapped rod  30  comprises a tobacco core surrounded by a paper wrapper. The length of the tipping paper  2  is L T  and the exposed length of the wrapped rod  1  (before the LIP bands A, B are applied) is L W . A first LIP band A has a first width W A  and is positioned spaced from an edge of the tipping paper  2  by a first distance a. A second LIP band B has a second width W B  and is spaced from an edge of the tipping paper  2  by a second distance b, which is longer than the first distance a. The tipping paper  2  is formed from the half of the central tipping section  12 A shown in  FIG. 1 , and the first band A is formed from one of the edge patch sections  12 B 1 ,  12 B 2 . The second band B can be formed from a further patch section of tipping paper split from the reel  13 . 
         [0029]    Preferably, the first band A is positioned within the first 50% of the exposed length of the wrapped rod  1  ie (W A +a)/ L W ≦0.5. Preferably, the second band B is spaced from the first band A and positioned within the last  50 % of the exposed length of the wrapped rod  1  ie (L W −b)/ L W ≦0.5. Preferably the width of the bands are approximately the same, i.e. W A =W B . 
         [0030]    In the preferred example, given a cigarette of 83 mm length, wherein the length L T  of the tipping paper  2  is 32 mm and the exposed length of the wrapped rod  1  L W  is 51 mm, a=11 mm, b=31 mm and W A =W B =6 mm. The base material used for the LIP bands is the same as that used for the tipping paper (although different printing may be used on each section) and preferably has a porosity of approximately 5 Coresta Units (CU). 
         [0031]    In an alternative to the embodiment shown in  FIG. 1 , rather than splitting the sections  12 A,  12 B 1 ,  12 B 2 , from a single reel  13  of tipping paper, each section may be provided from a separate reel. In this case, the outer patch sections  12 B 1 ,  12 B 2  need not be formed from the same material as the central tipping section  12 A. For example, the outer patch sections  12 B 1 ,  12 B 2  may be formed from the same material as the wrapper of the wrapped rods  30 . Alternatively, the outer patch sections  12 B 1 ,  12 B 2  may be formed from an alternative material, such as a plugwrap paper or a cigarette paper having a different weight or permeability to the cigarette paper forming the wrapping of the wrapped rods  30 . An example porosity is approximately 5 CU. 
         [0032]    As would be appreciated by those skilled in the art, the specific values chosen for the widths W A , W B  and sizes of the LIP patches, for the porosity of the LIP patches and for their position on the wrapped rod can be adjusted as appropriate to achieve a required reduction in ignition propensity and the location at which this will be effective. For example, LIP band widths above approximately 4 mm could be used, preferably between 4 mm and 25 mm and more preferably between approximately 4 mm and 10 mm. The porosity of the paper can be less than approximately 50 CU, preferably less than 10 CU and more preferably less than or equal to 5 CU. 
         [0033]    In a particular example, based on LIP performance measured according to the ASTM E2187-04 method, LIP-compliant cigarettes were manufactured having a single 5 CU porosity LIP band applied per cigarette in a 6 mm or 8 mm width and with the mouth-end edge of the band being 50 mm from the mouth end of the cigarette. The banding material was adhered to the tobacco rod with water-based glue. 
         [0034]    The width of the LIP patch  12 B 1 ,  12 B 2  may optionally be substantially equal to the length L W  of the region of wrapped tobacco rod  30  which is not covered by the sheet of tipping paper  2  connecting the wrapped rod  30  to the filter. For example,  FIG. 3  shows an LIP patch C which extends substantially from the edge of the tipping paper  2  which is furthest from the mouth end of the smoking article to the opposite end of the wrapped tobacco rod  30 . As can be seen, the LIP patch C comprises one or more windows  3  which expose the underlying wrapped tobacco rod  30  to the surrounding atmosphere. Each window  3  comprises a hole in the patch C of LIP material. The windows  3  may be cut-out from the LIP sheet material before the material is applied to the wrapped rod  30 . For example, the windows  3  can be cut-out from the material before the material is wound onto the bobbin or reel  13 . 
         [0035]    The regions of the patch C between the windows  3  fully circumscribe the wrapped tobacco rod  30 . Therefore, the regions of the patch which do not align with a window  3  can be considered as corresponding to the LIP bands A, B described above. The patch C thus provides the same LIP effect as the LIP patches A, B previously referred to. Specifically, burning of the wrapped tobacco rod  30  is hindered in the regions of the rod  30  which are covered by the LIP patch A, B, C whilst burning of the rod  30  is less hindered in the regions of the rod  30  which are not covered by the patch A, B, C. The rate of gaseous transfer between the tobacco and the surrounding environment, for example the surrounding air, through the windows  3  in the patch C mirrors the rate of gaseous transfer through the un-banded regions of the wrapped rod  30  shown in  FIG. 2  and as previously described. 
         [0036]    The location of the windows  3  may be opposite to the location of the LIP bands A, B described above. For example, as shown in  FIG. 3 , a first window  3  in the LIP patch C may extend between a location which is a distance of (a+W A ) from the edge of the tipping paper  2  and a location which is a distance b from the edge of the tipping paper  2 . The width of the first window is therefore (b−(a+W A )). Additionally or alternatively, a second window  3  may extend between a location which is a distance of (b+W B ) from the edge of the tipping paper  2  and a location which is a distance of L W  from the edge of the tipping paper  2 . The width of the second window  3  is therefore (L W −(b+W B )). This is also shown in  FIG. 3 . 
         [0037]      FIG. 4  shows another example, in which a window  3  extends between a location which is a distance of (a+W A ) from the edge of the tipping paper  2  and a location which is a distance of L W  from the edge of the tipping paper  2 . The width of the window  3  is therefore (L W −(a+W A )). 
         [0038]    Therefore, circumferential regions of LIP material are provided around the same regions of the wrapped tobacco rod  30  in both the embodiment shown in  FIG. 2  and the embodiments shown in  FIGS. 3 and 4 . Similarly, the wrapped tobacco rod  30  in between the circumferential regions of LIP material is largely exposed. 
         [0039]    The location, number and size of the windows in the patch C can be chosen in accordance with the desired LIP effect. Optionally, windows  3  may be provided in a circumferential band around the tobacco rod  30  so that two or more windows  3  are provided at the same longitudinal location on the rod  30 . The windows  3  can be of any suitable shape. 
         [0040]    If the LIP patch material comprises the same material that is used for the tipping paper  2 , a sheet of the material can optionally be applied over the whole length of a double length cigarette of the type shown in  FIG. 1  before cutting the double length filter in half. The windows  3  should be cut-out from the LIP material beforehand. 
         [0041]    In  FIGS. 3 and 4 , the tipping paper  2  and patch C are shown using a different pattern in order to allow the reader to clearly distinguish between the two. However, as has been explained, the tipping paper  2  and patch C may in practice be made of the same type of material.