WO2009098462A1

WO2009098462A1 - Tobacco smoke filter

Info

Publication number: WO2009098462A1
Application number: PCT/GB2009/000324
Authority: WO
Inventors: Paul Francis Clarke
Original assignee: Filtrona International Limited
Priority date: 2008-02-07
Filing date: 2009-02-06
Publication date: 2009-08-13
Also published as: JP5607544B2; CN101969797A; RU2585247C2; KR20100118132A; EP2242384A1; JP2011510674A; RU2010134019A

Abstract

A tobacco smoke filter or filter element comprising a longitudinally extending core of tobacco smoke filtering material having fully enclosed therewithin at least one pocket of a first additive; and a wrapper engaged around the core, the wrapper having a second additive adhered to one or more portion(s) of the radially inner face thereof with said wrapper being free of additive around its circumference at one end.

Description

TOBACCO SMOKE FILTER

The present invention relates to filters and filter elements for smoking articles such as cigarettes.

It is desirable to include particulate additives such as activated carbon in cigarette filters as a means of modifying the properties of the smoke. However, it is not aesthetically pleasing if the particulate additive is visible at the buccal end of the filter; further, such exposed additive may give a detrimental taste to the filter if applied to the mouth. In order to avoid the presence of particles at the buccal end, it is customary to use two or more filter segments aligned longitudinally along the filter length. In such filters, the mouth end segment generally comprises white fibrous material (typically cellulose acetate), and the tobacco end segment(s) includes particulate additive(s) in either a granular bed (e.g. sandwiched between the mouth end segment and a third, tobacco end segment); or embedded within a fibrous matrix. Filters of these types, known as 'Triple Granular', and 'Active Acetate Duals', respectively, are well known in the prior art. These multiple segment filter products have the disadvantage that several separate processes are required to manufacture the final filter - continuous rods of each base rod type are manufactured separately, the base rod elements subsequently being cut and combined in the chosen alignment in a separate process. This increases process complexity and may result in a higher manufacturing cost for filters incorporating particulate additives.

In order to overcome these disadvantages, the applicants have previously developed processes whereby particulate-bearing cigarette filters with at least one end free of additive can be produced in a single step. GB Patent No. 2,261 ,152 describes a wrapped cigarette filter in which the wrapper has particulate additive adhered to portions of its radially inner face, with one or both exposed ends of said wrapper being free of the additive. This is known as an 'Active Patch' filter. EP 1 ,827,144 describes a process for the pneumatic injection of localised pockets of particulate additive that are embedded in and longitudinally spaced along a continuously produced filter rod. The resultant product is known as a 'Pod' filter.

A limitation with these two processes is that the upper limit of the quantity of particulate additive, which can be incorporated within the filter, is lower than that which can be achieved in a conventional multi-segment filter of similar dimensions.

It is also desirable to include more than one additive in a filter. The inclusion of more than one additive in a filter can, for example, be easily achieved in a conventional Triple Granular' filter by using one additive in the granular bed and another embedded in the filter material of the upstream segment. However, a limitation with the single step 'Active Patch' and 'Pod' filters is that, unless the additive material comprises a homogeneous mixture of two or more additives of similar physical characteristics, it is not possible to incorporate more than one additive in the filter.

It is thus desirable to have a cigarette filter incorporating at least two particulate additives in separate locations which can be produced in a single pass process with at least one clean end.

According to the present invention there is provided a tobacco smoke filter or filter element comprising a longitudinally extending core of tobacco smoke filtering material having fully enclosed therewithin at least one pocket of a first additive; and a wrapper engaged around the core, the wrapper having a second (e.g. particulate) additive adhered to one or more portion(s) of the radially inner face thereof with said wrapper being free of (the second) additive around its circumference at one end. The wrapper may be free of (the second) additive around its circumference at both ends.

The longitudinally extending core of tobacco smoke filtering material may have fully enclosed therewithin one or more (e.g. two, three, four) separate pockets of a first additive. The fully enclosed (e.g. embedded) pockets of first additive may taper towards one or both ends - e.g. may be of a generally ellipsoidal configuration. If there is more than one pocket of first additive, these may have even longitudinal spacing. Other pocket dispositions are possible - e.g. relatively close longitudinal spacing alternating with longer spacing - it being possible to achieve this by appropriate adjustment of the manufacturing process. The filter or filter element may have a single embedded pocket of first additive close to one end (e.g. the tobacco end in a filter cigarette) and remote from the other end (e.g. the buccal end).

The second (e.g. particulate) additive may extend only partially around the inner circumference of the wrapper - the wrapper for example having an overlapping longitudinal edge which is free of second additive and provides a lapped and stuck seam holding the wrapper around the core. The second (e.g. particulate) additive may cover a single region of the inner surface of the wrapper extending from one end of the core partially towards the other; it may cover a single region which is spaced from both ends of the core; it may be disposed in separate regions spaced longitudinally and/or circumferentially from one another.

The applicants have found that a tobacco smoke filter or filter element may be produced in a single pass process with the benefit of a clean end or ends (e.g clean buccal end). The applicants have found that a tobacco smoke filter or filter element may include particulate additive at a higher loading than is possible with Active Patch and Pod filters, and/or may readily include more than one additive. The first additive may be a particulate additive. The first additive may be any particulate additive suitable for use in a tobacco smoke filter - e.g. activated carbon, zeolite, ion exchange resin (e.g. a weakly basic anion exchange resin), sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins and diatomaceous earths. The first (particulate) additive may be a mixture of two, or more, materials. The first additive may include a flavourant - e.g. menthol - e.g. the first additive may be sepiolite granules to which menthol has been applied. The pocket of particulate additive may be enclosed within the filtering material as a discrete pocket or pod of particles of particulate additive which is substantially separate from, and (e.g. predominantly) fully enclosed within, the filtering material. The term pocket or pod of particulate additive does not mean areas within the filter where individual particles of a particulate additive are (e.g. randomly) dispersed or interdispersed within a matrix (e.g. fibrous matrix) of filtering material. The first additive may be a frangible capsule or capsules, or one or a plurality of frangible microcapsules. The capsule(s) or microcapsule(s) may contain a variety of media - e.g. a flavourant and/or a liquid, solid or other material e.g. to aid smoke filtration. The use of capsules or microcapsules is well known in the prior art.

The applicants have found a further unexpected advantage when the first additive (enclosed fully within the filter body) is or includes a capsule or microcapsule(s), and the second particulate additive (on the inner surface of the wrapper) is activated carbon or other particulate additive; when the smoker presses the outside of the filter to break the frangible capsule or microcapsules (e.g. to release the flavourant) the second particulate additive facilitates a much more even breakage of the microcapsules. This is in addition to the known advantages of capsule and microcapsule containing filters - separating adsorbent and flavourant in a filter until the actual smoking of the cigarette (i.e. to minimise the loss of flavour by adsorption on the carbon and the loss of carbon activity through it adsorbing flavour during storage).

The second additive may be a particulate additive. The second additive may be any particulate additive suitable for use in a tobacco smoke filter - e.g. activated carbon, zeolite, ion exchange resin (e.g. a weakly basic anion exchange resin), sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins and diatomaceous earths.

The second particulate additive may be a mixture of two, or more, materials. The second particulate additive may include a flavourant - e.g. menthol - e.g. the second additive may be sepiolite granules to which menthol has been applied.

The first and second additives may be the same or they may be different.

The first additive and second additive may be the same e.g. when it is desired to increase the total additive loading (of e.g. activated carbon) that is to be applied during a single pass process.

The first additive and second additive may be different e.g. when it is desired for the additives to affect the smoke in a different manner. It is known that adsorbent additives, such as activated carbon, applied to the radially inner face (surface) of the wrapper are effective in reducing vapour phase compounds in smoke, and have a lesser influence on taste in this position than when they are included in a filter body. Thus, for example, in an embodiment of the invention, an adsorbent with a less desirable effect on taste (but capable of providing a beneficial reduction of toxic compounds from smoke) may be be used (as second additive) on the wrapper, whilst an adsorbent with a more favourable effect on smoke may be used as the first additive (fully enclosed within the longitudinally extending core of tobacco smoke filtering material). The weight of the first additive (e.g. a first particulate additive of around 0.5 g/cm³ density) fully enclosed within the longitudinally extending core of tobacco smoke filtering material may, for example, be between 10 and 65 mg, for example 20 and 50mg, for example between 25 and 40mg, per tip, for a filter tip of 20 to 30mm length. The weight of the first additive may, for example, be between 40 and 65 mg per tip, for a filter tip of 20 to 30mm length (e.g. if a high loading is required). The weight of the first additive may, for example, be between 10 and 40 mg per tip, for a filter tip of 20 to 30mm length (e.g. if a lower loading is required).

The weight of second additive (e.g. a second particulate additive of around 0.5 g/cm³ density) applied to the wrapper may, for example, be between 1 and 3.5 mg/linear mm (e.g. for a patch of 15 mm width). It will be appreciated that the weight of second additive may be altered by controlling, for example, the width of the patch, the weight of additive applied per unit area, and/or the physical properties of the additive.

The tobacco smoke filter may be of length between 15 and 40 mm, e.g. between 17 and 35 mm, e.g. between 20 and 30mm. The tobacco smoke filter element may be of length between 10 and 20 mm, e.g. between 12 and 19 mm, e.g. between 14 and 18mm. The tobacco smoke filter or filter element may be of circumference between 16 and 28 mm, for example between 20 and 26mm.

The filtering material forming the longitudinally extending core within which the additive pockets are embedded may be for example any of those materials (usually filamentary, fibrous, web or extruded) conventionally employed for tobacco smoke filter manufacture. The filtering material may be natural or synthetic filamentary tow, e.g. of cotton or plastics such as polyethylene or polypropylene, or cellulose acetate filamentary tow. It may be, for example, natural or synthetic staple fibres, cotton wool, web material such as paper (usually creped) and synthetic non-wovens, and extruded material (e.g. starch, synthetic foams).

According to the invention in a further aspect there is provided a multiple rod comprising a plurality (e.g. 2, 4, 6 etc.) of filters or filter elements as described above and/or herein integrally joined end-to-end in a mirror image relationship.

According to the invention in a further aspect there is provided a method of tobacco smoke filter production which comprises forming a continuous rod of tobacco smoke filtering material having fully enclosed therewithin longitudinally spaced pockets of a first additive; continuously advancing the continuous rod and a continuous strip having a second (e.g. particulate) additive adhered to a face thereof at longitudinally spaced regions; continuously wrapping the advancing strip around the advancing rod (optionally simultaneously with rod formation) with second additive against the rod; and cutting the resulting continuously produced wrapped rod into finite lengths. The continuous rod of tobacco smoke filtering material may be formed by continuously advancing a train of tobacco smoke filtering material longitudinally, gathering the advancing filtering material laterally such that it is shaped to and secured in rod form, and discontinuously pneumatically injecting the first additive (e.g. through an injector barrel or conduit, which is preferably stationary) laterally (e.g. radially) into the advancing gathering filtering material to form separate additive pockets embedded in and longitudinally spaced along the continuously produced rod. The continuous strip (e.g. plugwrap) having a second (e.g. particulate) additive adhered to a face thereof at longitudinally spaced regions may be formed by coating the strip with adhesive over the restricted regions where the second additive is required (e.g. with a printing wheel), and then with additive (e.g. by drawing through a reservoir, fluidised bed, circulated stream of additive etc.) whilst the adhesive is still active. The continuous strip (e.g. plugwrap) having a second (e.g. particulate) additive adhered to a face thereof at longitudinally spaced regions may be formed as part of the inline continuous process. In an alternative embodiment, adhesive coated strip may be separately produced or obtained from an outside supplier, with activation (e.g heat softening) of adhesive and application of second additive being conducted in-line and with filter production.

An apparatus used to manufacture filters, filter elements, multiple rods etc. acccording to the invention is similar to that described in EP 1 ,827,144 for the discontinuous pneumatic injection of first (e.g. particulate additive) laterally into a gathering tobacco smoke filtering material, but in which the plugwrap (item 52 on figure 1 of EP 1 ,827,144) has the second (e.g. particulate) additive adhered to its inner face at longitudinally spaced regions, e.g. by coating the strip with adhesive over the restricted regions where the second additive is required (e.g. with a printing wheel), and then with additive. The positioning of the second additive on the outer wrapper may be synchronised with the positioning of the internal pocket of first additive so that the respective positions of these two additive regions to each other can be controlled. In addition, the location of the additives may be synchronised with the operation of the cutter (which severs the continuously produced train of filter material into discrete filter rods etc) such that cutting takes place in zones that are free of additive.

A filter according to the invention is likely to be used on its own e.g. as a single segment filter. Such filters are well known in the art. It is also possible that a filter element according to the invention may be used as a segment of a multi-segment filter, e.g. a dual, triple, other multiple filter - although the advantages of single pass filter production may be lost. Such filters are well known in the art.

According to the invention in a further aspect there is provided a tobacco smoke filter element comprising a longitudinally extending core of tobacco smoke filtering material having substantially fully enclosed therewithin at least one pocket of an additive. The pocket may be fully enclosed within the longitudinally extending core of tobacco smoke filtering material. The tobacco smoke filter element may be of length between 10mm and 20mm, e.g. between 12mm and 19mm, e.g. between 14mm and 18mm. The filter element may further comprise a wrapper engaged around the core.

In this aspect the filter element does not include a second additive on the wrapper. However, some advantages of use of different additives may be provided by using a filter element according to this aspect of the invention as a segment of a multi-segment filter, e.g. a dual, triple, other multiple filter, wherein one of the other segments includes a second additive. The filter element according to this aspect of the invention may be used as the buccal end segment of such a filter, e.g. to provide clean end appearance (in which case the pocket is fully enclosed within the longitudinally extending core of tobacco smoke filtering material). The filter element according to this aspect of the invention may be used in another position in the filter (e.g. as the tobacco end segment); in this case a clean end apperaance may be less important and the pocket may be substantially fully enclosed within the longitudinally extending core of tobacco smoke filtering material (e.g. there may be a small amount of additive from the pocket visible at one (or both) ends of the longitudinally extending core of tobacco smoke filtering material)

Herein, the term filter element means a filter component or filter segment, which, together with other components or segments, makes up a tobacco smoke filter - for example a filter element may form a segment of a multi-segment filter. This is different to a filter which herein means a complete filter (which may include filter elements).

The additive may be a particulate additive. The additive may be any particulate additive suitable for use in a tobacco smoke filter - e.g. activated carbon, zeolite, ion exchange resin (e.g. a weakly basic anion exchange resin), sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins and diatomaceous earths. The additive may be a mixture of two, or more, materials. The additive may include a flavourant - e.g. menthol - e.g. the additive may be sepiolite granules to which menthol has been applied. The additive may be a frangible capsule or capsules, or one or a plurality of frangible microcapsules. The capsule(s) or microcapsule(s) may contain a variety of media - e.g. a flavourant and/or a liquid, solid or other material e.g. to aid smoke filtration. The use of capsules or microcapsules is well known in the prior art. An apparatus used to manufacture filter elements, multiple rods etc. acccording to this aspect of the invention is similar to that described in EP 1 ,827,144 for the discontinuous pneumatic injection of additive laterally into a gathering tobacco smoke filtering material, adapted to cut the product rod into shorter lengths (and, for example, adapted or set to insert pockets closer together along the length of the product rod). .

According to the invention in a further aspect there is provided a tobacco smoke filter comprising a longitudinally extending core of tobacco smoke filtering material having fully enclosed therewithin at least one pocket of an additive, wherein the additive is a frangible capsule or capsules, or one or a plurality of frangible microcapsules. An apparatus used to manufacture filters, multiple rods etc. acccording to this aspect of the invention is similar to that described in EP 1 ,827,144 for the discontinuous pneumatic injection of additive laterally into a gathering tobacco smoke filtering material.

As with other aspects of the invention, the filtering material forming the longitudinally extending core within which the additive pockets are embedded may be for example any of those materials (usually filamentary, fibrous, web or extruded) conventionally employed for tobacco smoke filter manufacture. The filtering material may be natural or synthetic filamentary tow, e.g. of cotton or plastics such as polyethylene or polypropylene, or cellulose acetate filamentary tow. It may be, for example, natural or synthetic staple fibres, cotton wool, web material such as paper (usually creped) and synthetic non-wovens, and extruded material (e.g. starch, synthetic foams).

In a filter cigarette according to the invention, a filter of the invention (or a filter which includes a filter element of the invention) is joined to a wrapped tobacco rod with one end of the filter towards the tobacco. The filter may, for example, be joined to the wrapped tobacco rod by ring tipping [which engages around just the adjacent ends of the (wrapped) filter and rod to leave much of the filter wrap exposed] or by a full tipping overwrap (which engages around the full filter length and the adjacent end of the tobacco rod).

Any filter or filter cigarette according to the invention may be unventilated, or may be ventilated by methods well known in the art, e.g. by use of a pre-perforated or air-permeable wrapper (plugwrap), and/or laser perforation of wrapper (plugwrap) and tipping overwrap. A ventilating full tipping overwrap may likewise be inherently air-permeable or provided with ventilation holes, and in ventilated products where both filter plugwrap and tipping overwrap are present ventilation through the overwrap will usually be in register with that through the plugwrap. Ventilation holes through a filter plugwrap, or through a tipping overwrap, or through both simultaneously, may be made by laser perforation during filter or filter cigarette production.

Where ventilation in a filter or filter cigarette according to the invention is localised longitudinally of the product, this localisation is preferably to one or two regions selected from upstream of, downstream of, and in register with the or a pocket of first additive, depending upon the ventilation and filtering performances required; ventilation upstream of and/or in register with a pocket of first additive is frequently preferred. The localisation (of ventilation) may be to one or two regions selected from upstream of, downstream of, or, less preferably, in register with a portion of second additive. There may be ventilation between portions of second additive when two or more are present.

The present invention will now be illustrated with reference to the following Examples and the attached drawings in which FIGURE 1 schematically illustrates a cylindrical quadruple length filter rod according to an embodiment of the invention; FIGURE 2 schematically illustrates a cylindrical quadruple length filter rod according to a second embodiment of the invention; FIGURE 3 schematically illustrates a cylindrical quadruple length filter rod according to a further embodiment of the invention; FIGURE 4 schematically illustrates a cylindrical quadruple length filter rod according to a different further embodiment of the invention; and FIGURE 5 schematically illustrates a cylindrical quadruple length filter rod according to a different still further embodiment of the invention.

Figure 1 (not to scale) shows a cylindrical quadruple length filter rod 1 supplied for filter cigarette manufacture that is 108mm in length and 24.5mm in circumference. During cigarette manufacture, the illustrated quadruple length rod would normally be severed at the half way point to give two double length rods; each double length rod would then have two wrapped tobacco rods attached thereto (by means well known in the art), one at each end, followed by cutting at the half way point to yield two filter cigarettes. Thus, the illustrated rod comprises four filter tips each of 27mm length joined end to end in a mirror image relationship.

The rod 1 and (each filter tip) includes a longitudinally extending core 3 of tobacco smoke filtering material in the form of cellulose acetate tow, and a wrapper 4 of plugwrap engaged around the core 3. The core 3 has fully enclosed therewithin four pockets 5 of a first additive in the form of activated carbon granules (each of 40mg weight) placed at equal intervals along the rod. Three patches 6, 6a, 6b of second particulate additive in the form of activated carbon granules are adhered to the inner surface of the plugwrap. Patches 6a and 6b are strips of 15 mm width (i.e. in the direction around the circumference) and 22 mm length (i.e. in the direction along the rod); patch 6a extends from one end of rod 1 ; patch 6b from the other. Thus, each patch 6a, 6b extends 22 mm from an end of rod 1. Patch 6 is a strip of 15 mm width (i.e. in the direction around the circumference) and 44 mm length (i.e. in the direction along the rod) with its central point located halfway along rod 1. There are two strips, each of 10 mm length, in the filter rod where carbon is not applied to the wrapper at any point on its circumference; the first is located between the internal end of patch 6a (i.e. the end which is not at the filter end) and one end of patch 6, the other is located between the internal end of patch 6b, and the other end of patch 6. The carbon loading on each patch 6 is 3 mg/linear mm.

The patches 6, 6a, 6b extend only partially around the inner circumference of wrapper 4; the wrapper 4 has an overlapping longitudinal edge which is free of second additive to which adhesive is applied to provide a lapped and stuck seam (not shown) holding the wrapper around the core (as is well known in the art).

Thus, when the rod 1 is cut into four filter tips, each tip of 27 mm length will include a 27mm long core of cellulose acetate tow having a single pocket of 40mg activated carbon granules enclosed therein; and a wrapper of plugwrap engaged around the core having a single patch of activated carbon of length 22 mm and width 15mm adhered to the radially inner face thereof; with a strip of length 5mm at (extending from) one end of the wrapper where no activated carbon is adhered thereto. Thus, no second additive (activated carbon) is visible at this end of the filter. The (each) filter tip has a carbon loading of 106mg (40 mg in the embedded pocket 5 and 66 mg on the plugwrap in patch 6). An apparatus used to manufacture the filter rod 1 is similar to that described in EP 1 ,827,144 for the discontinuous pneumatic injection of a pocket of particulate additive laterally into a gathering tobacco smoke filtering material, but in which the wrapper 4 of plugwrap (item 52 on figure 1 of EP 1 ,827,144) has particulate additive adhered to its inner face at longitudinally spaced regions by techniques known in the art, e.g. by coating the strip with adhesive over the restricted regions where the second additive is required (e.g. with a printing wheel), and then with additive (see e.g. GB 2261152). The positioning of the particulate additive on the wrapper 4 is synchronised with the positioning of the internal pocket of additive so that the respective positions of these two additive regions to each other are controlled. In addition, the location of these additives is synchronised with the operation of the cutter (which severs the continuously produced train of filter material into discrete filter rods 1) such that cutting of the final filter cigarette will only take place in zones that are free of additive. The embodiments of Figures 2 to 5 may be made by similar techniques. It will be appreciated that alternative methods of making the product are possible without departing from the spirit of the invention - e.g. positioning the pocket of particulate additive by means other than discontinuous injection or by using a plugwrap that has been pre-coated with localised patches of particulate additive.

Figure 2 shows a filter rod V similar to that described in figure 1, having strips of length 3 mm extending from each end of the rod where carbon is not applied to the wrapper at any point on its circumference; and a further strip 7 of length 6 mm in the middle of the filter rod where carbon is not applied to the wrapper at any point on its circumference. The filter rod 1' is cut into four individual filter tips of length 27mm which are free of particulate additive at both ends. Each tip of 27 mm length will include a

27mm long core of cellulose acetate tow having a single pocket of 40mg activated carbon granules enclosed therein; and a wrapper of plugwrap engaged around the core having a single patch (6¹) of activated carbon of length 19 mm and width 15mm adhered to the radially inner face thereof; with a strip of length 5mm at (extending from) one end of the wrapper and another of length 3mm at (extending from) the other end where no activated carbon is adhered thereto. Each filter tip has a carbon loading per tip mg of 97mg (40 mg in the central pocket and 57 mg on the plugwrap).

Figure 3 shows a filter rod similar to that described in figure 2, only there are four additional strips of 4 mm where no activated carbon is adhered to the wrapper; these strips are located between 11mm and 15mm; 39mm and 43mm; 65mm and 69mm; and 93mm and 97mm from the rod end. Each tip of 27 mm length will include a 27mm long core of cellulose acetate tow having a single pocket of 40mg activated carbon granules enclosed therein; and a wrapper of plugwrap engaged around the core having two patches 6", 6"^b of activated carbon (the first patch 6" of length 8 mm; the second patch 6"^b of length 7mm, both patches of width 15mm) adhered to the radially inner face thereof; with a strip of length 5mm extending from one end of the wrapper to patch 6"^b and another of length 3mm extending from the other end to patch 6" (and a third of width 4mm between patches 6" and 6"^b) where no activated carbon is adhered thereto. This will result in a carbon loading per tip mg of 85mg (40 mg in the central pocket and 45 mg on the plugwrap). This configuration enables each individual filter tip, when incorporated into a cigarette with a ventilated filter, to have an area directly underneath the ventilation zone (i.e. that corresponding to the gap between patches 6" and 6"^b) that is free of particulate additive.

Figure 4 shows a filter rod similar to that described in figure 3, but in this embodiment the core 3'" has fully enclosed therewithin four pockets of a first additive in the form of frangible microcapsules 10 containing flavourant (these are injected into the core in place of the mass of carbon granules e.g. by similar technique). The presence of the patches 6'", 6"'^b of carbon granules in the plugwrap advantageously enables a more even breaking of the microcapsules 10 to take place when the smoker presses the outside of the filter. Figure 5 shows a filter rod similar to that described in figure 4, but in this further embodiment the core 3"" has fully enclosed therewithin four pockets of a first additive in the form of a single capsule 11 containing flavourant. The presence of the patches 6"", 6""^b of carbon granules in the plugwrap again enables a more even breaking of the capsule to take place when the smoker presses the outside of the filter.

In an embodiment of another aspect of the invention (not shown) there is provided a filter element of 14 mm length and 24.5mm circumference including a 12mm long core of cellulose acetate tow having a single pocket of 25mg activated carbon granules enclosed -therein; and a wrapper of plugwrap engaged around the core. An apparatus used to manufacture this filter element (and multiple rods etc. thereof) is similar to that described in EP 1 ,827,144 for the discontinuous pneumatic injection of additive laterally into a gathering tobacco smoke filtering material.

Claims

1. A tobacco smoke filter or filter element comprising a longitudinally extending core of tobacco smoke filtering material having fully enclosed therewithin at least one pocket of a first additive; and a wrapper engaged around the core, the wrapper having a second additive adhered to one or more portion(s) of the radially inner face thereof with said wrapper being free of additive around its circumference at one end.

2. A tobacco smoke filter or filter element according to claim 1 wherein the first additive is a particulate additive.

3. A tobacco smoke filter or filter element according to claim 1 or claim 2 wherein the first additive is activated carbon, zeolite, ion exchange resin (e.g. a weakly basic anion exchange resin), sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins or a diatomaceous earth.

4. A tobacco smoke filter or filter element according to claim 1 wherein the first additive is a frangible capsule or capsules, or one or a plurality of frangible microcapsules.

5. A tobacco smoke filter or filter element according to any preceding claim wherein the second additive is a particulate additive.

6. A tobacco smoke filter or filter element according to any preceding claim wherein the second additive is activated carbon, zeolite, ion exchange resin (e.g. a weakly basic anion exchange resin), sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins or a diatomaceous earth.

7. A tobacco smoke filter or filter element according to any preceding claim wherein the weight of the first additive fully enclosed within the longitudinally extending core of tobacco smoke filtering material is between 10 and 65 mg, for a filter tip of 20 to 30mm length.

8. A tobacco smoke filter or filter element according to any preceding claim wherein the weight of the second additive is between 1 and 3.5 mg/linear mm.

9. A tobacco smoke filter or filter element according to any preceding claim wherein the first and second additives are the same.

10. A tobacco smoke filter or filter element according to any preceding claim wherein the first and/or second additive includes a flavourant.

11. A tobacco smoke filter or filter element substantially as hereinbefore described with reference to the description and/or the attached drawings.

12. A filter cigarette including a filter according to any preceding claim, or a filter which includes a filter element according to any preceding claim, joined to a wrapped tobacco rod.

13. A multiple rod comprising a plurality of filters or filter elements according to any of claims 1 to 11 integrally joined end-to-end in a mirror image relationship.

14. A multiple rod substantially as hereinbefore described with reference to the description and/or the attached drawings.

15. A method of tobacco smoke filter production which comprises forming a continuous rod of tobacco smoke filtering material having fully enclosed therewithin longitudinally spaced pockets of a first additive; continuously advancing the continuous rod and a continuous strip having a second additive adhered to a face thereof at longitudinally spaced regions; continuously wrapping the advancing strip around the advancing rod with second additive against the rod; and cutting the resulting continuously produced wrapped rod into finite lengths.

16. A method according to claim 15 in which the continuous rod of tobacco smoke filtering material is formed by continuously advancing a train of tobacco smoke filtering material longitudinally, gathering the advancing filtering material laterally such that it is shaped to and secured in rod form, and discontinuously pneumatically injecting the first additive laterally into the advancing gathering filtering material to form separate additive pockets embedded in and longitudinally spaced along the continuously produced rod.

17. A method according to claim 15 or 16 in which the continuous strip having a second additive adhered to a face thereof at longitudinally spaced regions is formed by coating the strip with adhesive over the restricted regions where the second additive is required, and then with additive.

18. A tobacco smoke filter element comprising a longitudinally extending core of tobacco smoke filtering material having substantially fully enclosed therewithin at least one pocket of an additive.

19. A tobacco smoke filter element according to claim 18 of length between 10 mm and 20mm.

20. A tobacco smoke filter element according to claim 18 or 19 wherein the additive is a particulate additive.

21. A tobacco smoke filter element according to claim 18, 19 or 20 wherein the additive is activated carbon, zeolite, ion exchange resin (e.g. a weakly basic anion exchange resin), sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins or a diatomaceous earth.

22. A tobacco smoke filter element according to any of claims 18 to 21 further comprising a wrapper engaged around the core.

23. A filter cigarette including a filter element according to any of claims 18 to 22, joined to a wrapped tobacco rod.

24. A multiple rod comprising a plurality of filter elements according to any of claims 18 to 22 integrally joined end-to-end in a mirror image relationship.