AEROSOL GENERATING ARTICLES

Abstract

A filter part (1, 1) for use in an aerosol generating article and a method of manufacturing the filter part (1, 1). The filter part (1, 1) includes an aerosol permeable core extrusion (2) surrounded by a sleeve (3) formed of predominantly linear, axially oriented fibres. The method includes forming two or more strips (4a, 4b) into segments surrounding a conveying path, bringing the segments together into a sleeve former (7) to form the sleeve (3) and introducing an aerosol permeable core extrusion (80) between the segments upstream of the sleeve former (7) and bonding the segments together to form a sleeve surrounding the core extrusion (80), thereby forming a filter rod (9). The filter rod (9) is then cut to form the filter part (1, 1).

Claims

1. An aerosol permeation element for use in an aerosol generating article, the aerosol permeation element comprising an aerosol permeable core extrusion surrounded by a sleeve comprising predominantly linear, axially oriented fibres; wherein the sleeve comprises two or more longitudinal segments which are bonded together along longitudinal edges of the segments.

2. Aerosol permeation element according to claim 1, wherein the core extrusion comprises a foamed polymeric extrusion with one or more pathways described therealong.

3. Aerosol permeation element according to claim 1, wherein at least one of the pathways is described within the core extrusion and at least one of the pathways is described by a channel on an outer surface thereof which cooperates with the sleeve.

4. Aerosol permeation element according to claim 1, wherein the sleeve comprises two or more longitudinal segments formed from the same tow and the tow material of the longitudinal segments is bonded together at least along their longitudinal edges to form an integral sleeve.

5. Aerosol permeation element according to claim 1, wherein the core extrusion comprises a poly lactic acid, acetate or cellulose material.

6. Aerosol permeation element according to claim 1, wherein the sleeve comprises cellulose acetate or poly lactic acid fibres.

7. Aerosol permeation element according to claim 1, wherein the sleeve comprises a wall thickness of between 0.5 millimetres and 3 millimetres.

8. Aerosol permeation element according to claim 1, wherein the core extrusion comprises a diameter of between 2 millimetres and 8 millimetres.

9. An aerosol generating article comprising an aerosol permeation element according to claim 1.

10. A method of manufacturing an aerosol permeation element for use in an aerosol generating article, the method comprising: separating a tow into two or more strips which are formed into segments surrounding a conveying path; introducing an aerosol permeable core extrusion between the segments; and bonding the segments together to form a sleeve surrounding the core extrusion.

11. Method according to claim 10, wherein the core extrusion is introduced between the segments as a foamed polymeric extrusion with one or more pathways described therealong.

12. Method according to claim 10 comprising extruding a core material through a die to form the core extrusion and supplying the core extrusion from the die for introduction between the segments.

13. Method according to claim 12 comprising passing the extruded core material through a cooling bath prior to introducing the core extrusion between the segments.

14. Method according to claim 10 comprising supplying the core extrusion from a pre-extruded roll.

15. (canceled)

Description

[0053] FIG. 1 is a perspective view of an aerosol permeation element according to an embodiment of the invention;

[0054] FIG. 2 is a transverse cross-sectional view of the aerosol permeation element of FIG. 1;

[0055] FIG. 3 is a cross-sectional view of the aerosol permeation element of FIGS. 1 and 2 along its longitudinal axis;

[0056] FIG. 4 is a cross-sectional view of an aerosol permeation element according to another embodiment of the invention;

[0057] FIG. 5 is a schematic of a filter manufacturing apparatus according to an embodiment of the invention;

[0058] FIG. 6 is a schematic of a tow as it is formed into two strips;

[0059] FIG. 7 is a cross-sectional view through the core die of the apparatus of FIG. 5; and

[0060] FIG. 8 is a schematic of a filter manufacturing apparatus according to another embodiment of the invention.

[0061] Referring now to FIGS. 1 to 3 show an aerosol permeation element 1 according to an embodiment of the invention, which is a filter part 1 for an aerosol generating article (shown in outline). The filter part 1 in this embodiment includes an aerosol permeable core 2 of extruded polymeric filter material surrounded by a sleeve 3 of linear, axially oriented fibres. The core 2 has a plurality of pathways 21 described within it, which extend along its axial length. The core 2 is formed from a poly lactic acid (PLA) material in this embodiment and has a diameter D of 5 millimetres. In this embodiment, the sleeve 3 has a wall thickness W of 1 millimetres.

[0062] FIG. 4 shows a filter part 1 similar to that of FIGS. 1 to 3, wherein like references depict like features. The filter part 1 according to this embodiment differs from that of FIGS. 1 to 3 in that a plurality of channels 22 are described along the outer surface of the core 2. The channels 22 define, together with the internal surface of the sleeve 3, further pathways 23 along the length of the core 2.

[0063] FIGS. 5 to 7 show an apparatus 10 for manufacturing filter parts 1, 1 according to FIGS. 1 to 4. As illustrated in FIG. 5, a length of tow 4 is fed through a separator 5, which separates the tow 4 into two strips 4a, 4b, which are then fed over a guide 6 and into a sleeve former 7. Simultaneously, a core forming apparatus 8 forms an aerosol permeable core extrusion 80, which is fed through the guide 6 along a conveying path and introduced between the strips 4a, 4b as they pass over the guide 6 and into the sleeve former 7. The sleeve former 7 brings the strips 4a, 4b and core extrusion 80 together and joins the strips 4a, 4b together around the core extrusion 80 to form a filter rod 9.

[0064] In this embodiment, the tow 4 is formed of poly lactic acid (PLA) fibres aligned longitudinally along its length. The tow separator 5 includes a pair of opposed, counter-rotating separation rollers 5a, 5b configured, in use, to rotate in the conveying direction of the apparatus 10 at a speed R1. The separation rollers 5a, 5b have cooperating cutters or blades (not shown), which slit the tow 4 as it passes therebetween to create the strips 4a, 4b.

[0065] The guide 6 is also downstream of the tow separator 5 and includes a pair of opposed, spaced part-conical and tubular guide members 61a, 61b. An upper guide member 61a lies above the conveying path of the core extrusion 80 and a lower guide member 61b lies below the conveying path. Together, the guide members 61a, 61b partially surround the conveying path, with a vertical gap between them. Each of the guide members 61a, 61b tapers inwardly toward the sleeve former 7. The downstream ends of the guide members 61a, 61b are spaced from the sleeve former 7. The apparatus 10 in this embodiment also includes plasticizer sprayers 40 that apply a plasticizer to the strips 4a, 4b as they pass between the guide members 61a, 61b and the sleeve former 7.

[0066] The sleeve former 7 has a first, conical segment or forming funnel 71 and a second, tubular element 72 downstream of the conical segment 71. The conical segment 71 tapers inwardly along a conveying direction to the diameter of the tubular element 72. The sleeve former 7 is heated in this embodiment, such that the strips 4a, 4b of tow 4 are bonded together by both heat and compression as they are conveyed, together with the core extrusion 80, through the sleeve former 7. The apparatus 10 also includes a drawing mechanism (not shown), which provides a drawing force F to draw the completed filter rod 9 through and out of the tubular element 72 of the sleeve former 7. The apparatus 10 may also include an integral cutting station (not shown) downstream of the sleeve former 7 to cut the filter rod 9 into filter parts 1, 1. Alternatively, the filter rod 9 may be fed into another apparatus for further processing.

[0067] The core forming apparatus 8 includes an extruder 81 with a hopper 81a for feeding raw material, a poly lactic acid (PLA) resin in this embodiment, to the extruder 81. The extruder 81 extrudes core material through a core die 82 and the core material is drawn therefrom through a cooling unit 83 using a core drawing mechanism 84. Downstream of the core drawing mechanism 84, the extruded core 80 is fed to the conveying path by alignment rollers 85a, 85b.

[0068] As shown more clearly in FIG. 7, the downstream end of the extruder 81 includes a flow channel 81b leading to the core die 82. The core die 82 has a male part 86 and a female part 87 described by an outer wall 87a that defines the outer surface of the extrusion. The male part 86 is supported within the female part 87 by support elements (not shown) and has a plurality of core members 86a each having a circular cross-section for creating the pathways within the extrusion. The circular core members 86a together define a star pattern so as to form the pathways 21 along the core extrusion 80. The core die 82 is attached to the outlet of the core extruder 81 for receiving molten material therefrom. Optionally, the male part 86 may rotate within the female part 87 such that the core members 86a create helical or helicoidal pathways within the extrusion. The helical angle of the pathways may be controlled by the speed of rotation of the male part 86 relative to the drawing speed of the extrusion.

[0069] Downstream of the core die 82 is the cooling unit 83 which includes a tank 83a having a cooling medium therein, water in this embodiment. Extruded material is drawn by the drawing mechanism 84 from the extruder 81 into the tank 73a and through a final die 83b, which is below the surface of the water. The final die 83b is tubular with an internal diameter which is substantially the same as the diameter of the extruded core 80 and substantially smaller than the diameter of the female part 87 of the core die 82. As such, the extruded material forms a conical extrusion 80a as it passes from the core die 82 to the inlet of the cooling tank 83a.

[0070] The core forming apparatus 8 also includes a drying ring 88 downstream of the cooling tank 83a, which removes any remaining water on the surface of the extruded core 80. The drawing mechanism 84 is downstream of the drying ring 88 and includes a pair of opposed, counter-rotating pulling rollers 84a, 84b arranged to receive the extruded core 80 after it has passed through the cooling unit 83 and drying ring 88. The pulling rollers 84a, 84b receive the extruded core 80 therebetween, draw it through the cooling unit 83 and convey it to the conveying path via the alignment rollers 85a, 85b.

[0071] A first alignment roller 85a is external of the conveying path, while a second alignment roller 85b is within the conveying path, between the guide members 61a, 61b. The extruded core 80 is fed from the core forming apparatus 8 to the conveying path between the tow separator 5 and the guide 6 via the alignment rollers 85a, 85b. The extruded core 80 then enters the forming funnel 71 of the sleeve former 7 between the strips 4a, 4b, downstream of the tow separator 5. As illustrated in FIG. 5, the axes of rotation of the alignment rollers 85a, 85b lie at an angle relative to the separation rollers 5a, 5b to enable transverse feeding of the core extrusion 80 through the vertical gap between the strips 4a, 4b. In this embodiment, the alignment rollers 85a, 85b are non-driven.

[0072] In use, a length of tow 4 is fed into the tow separator 5, where it passes between the rollers 5a, 5b and is split into the two strips 4a, 4b. The strips 4a, 4b are separated from the conveying path, with a first strip 4a passing over the upper guide member 61a and a second strip 4b passing over the lower guide member 61b. The strips 4a, 4b expand and conform to the profile of the respective guide member 61a, 61b as they are passed thereover. The guide members 61a, 61b create tension in the strips 4a, 4b and guide them toward the sleeve former 7. The guide members 61a, 61b deform and stretch the strips 4a, 4b into part-conical, tubular segments that partially surround the conveying path of the core extrusion 80. The plasticizer sprayers 40 apply a plasticizer to the so-formed strips 4a, 4b before they enter the sleeve former 7.

[0073] Simultaneously, raw material for forming the core extrusion 80 is fed from the hopper 81a through the extruder 81. Extruded core material 80a is drawn through the cooling unit 83 by the drawing mechanism 84, which cools and solidifies it into the core extrusion 80. The core extrusion 80 is also drawn through the final die 83b, which ensures that its diameter is correct. The core extrusion 80 is drawn by the pulling rollers 84a, 84b of the drawing mechanism 84 and fed to the sleeve former 7 via the alignment rollers 85a, 85b.

[0074] The longitudinal edge regions of the strips 4a, 4b overlap as they enter the sleeve former 7. As such, the overlapping regions are bonded together, using heat and compression, as the strips 4a, 4b pass through the sleeve former 7 such that they describe a sleeve surrounding the core extrusion 80 to form a length of filter rod 9. The application of a plasticizer not only facilitates the bonding of the strips 4a, 4b, but it also causes the core extrusion 80 to adhere to the strips 4a, 4b as they come into contact with them. The drawing mechanism (not shown) applies a force F to draw the finished filter rod 9 through and out of end of the tubular element 72 for processing or cutting into a plurality of filter parts 1, 1, or both processing and cutting into a plurality of filter parts. As the strips 4a, 4b are formed from the same tow 4, the sleeve 3 of an aerosol permeation element 1, 1 made using this apparatus 10 is formed from the same material. This reduces the likelihood of deformation in the finished filter element 1, 1.

[0075] Turning now to FIG. 8, there is shown an alternative apparatus 100 for manufacturing aerosol permeation elements 1, 1 according to FIGS. 1 to 4. The apparatus 100 according to this embodiment is similar to that of FIG. 5, wherein like references depict like features that will not be described further herein. The apparatus 100 according to this embodiment differs from that of FIG. 5 in that the core extrusion 80 is supplied from a pre-formed roll 108 instead of being manufactured in parallel.

[0076] As such, in this embodiment, the core forming apparatus 8 is completely separate from the aerosol permeation element manufacturing apparatus 100. This arrangement may be advantageous in some circumstances. For example, where multiple shorter runs of different filter rods 9 (for example, having cores 2 or sleeves 3 with different characteristics, or both cores and sleeves with different characteristics) are required, these can be manufactured by simply replacing the roll 108.

[0077] It will be appreciated by those skilled in the art that the parameters of the filter part 1, 1 may be altered by changing one or more processing parameters. For example, the thickness of the sleeve 3 may be increased or decreased by modifying the extent to which the strips 4a, 4b are stretched, for example by changing the difference between the speed R1 of the separation rollers 4a, 4b and the rate at which the filter rod 9 is drawn. Moreover, the size and density of the pathways 21, 23 in each of the filter parts 1, 1 may be selected to provide the appropriate resistance to draw for the filter part 1. This is preferably between 0.5 millimetres, water gauge (mmWG) and 2 millimetres, water gauge mmWG per millimetre of axial length of the filter part 1.

[0078] As such, the invention provides a versatile means of producing aerosol permeation elements 1 whose characteristics can be varied across a wide range.

[0079] It will be appreciated by those skilled in the art that several variations to the aforementioned embodiments are envisaged without departing from the scope of the invention. For example, the number of strips 4a, 4b used to form the sleeve 3 may be more than two in number. The strip or strips 4a, 4b used to form the sleeve may undergo further intermediate processing, for example chemical processing, to alter their properties. Moreover, while the strips 4a, 4b are described as being bonded together using heat and pressure, this need not be the case. They may be secured together using an adhesive. Similarly, the strips 4a, 4b need not include a plasticizer applied thereto. Other variations are also envisaged and would be appreciated by those skilled in the art.

[0080] It will also be appreciated by those skilled in the art that any number of combinations of the aforementioned features or those shown in the appended drawings provide clear advantages over the prior art and are therefore within the scope of the invention described herein.