WO2008075032A1

WO2008075032A1 - Tobacco smoke filter

Info

Publication number: WO2008075032A1
Application number: PCT/GB2007/004868
Authority: WO
Inventors: John Richardson; Dean Milburn
Original assignee: Filtrona International Limited
Priority date: 2006-12-19
Filing date: 2007-12-18
Publication date: 2008-06-26

Abstract

A method of producing a multi-component filter or multiple component filter rod comprising the steps of : arranging alternating cylindrical plugs of a first filtering material (22) and a second filtering material (14) so as to provide groups of three plugs comprising a plug of first filtering material abutted at either end with a plug of second filtering material, each such group longitudinally spaced at each end from a plug of first filtering material; introducing a particulate additive into the space (301) between each group of three plugs and each single plug; applying a filter wrapper material around the cylindrical plugs and particulate additive to form a continuous rod of wrapped plugs and particulate additive; and cutting the continuous rod across the plugs of first filtering material.

Description

TOBACCO SMOKE FILTER

The present invention relates to tobacco smoke filters, especially for cigarettes. In particular, it relates to tobacco smoke filters which include particulate additives such as activated carbon.

It is often desirable to include two different additives, each having a different effect, in a filter. If two (or more) additives are present, it is desirable to include these separately within the filter.

Triple granular filters for cigarettes are well known in the art. These include a cylindrical downstream (buccal end) filtering plug, a cylindrical upstream (tobacco end) filtering plug, and a filter wrapper engaged around the plugs to form a cavity between the upstream and downstream filtering plugs. Often, particulate additives such as granules of activated carbon are included within the cavity. It is also known to make triple granular filters as described above which include two additives, one in the cavity, the other in the tobacco (or upstream) end plug (it is not usual to include additive in the downstream end plug because this will provide undesirable end appearance at the mouth end of the filter). A problem with triple granular filters, which include two additives, as described above is that, when applying the filter to a cigarette, the cigarette manufacturer has to cut through a segment/component (the tobacco end segment) which contains an additive, with the risk of contamination of the cigarette assembly process and machinery. Further, if cigarettes have to be reclaimed, the additive may contaminate the reclaimed tobacco.

According to the present invention there is provided a method of producing a multi-component cigarette filter or multiple component filter rod comprising the steps of:

arranging alternating cylindrical plugs of a first filtering material and a second filtering material so as to provide groups of three plugs comprising a plug of first filtering material abutted at either end with a plug of second filtering material, each such group longitudinally spaced at each end from a single plug of first filtering material; introducing a particulate additive into the space between each group of three plugs and each single plug;

applying a filter wrapper material around the cylindrical plugs and particulate additive to form a continuous rod of wrapped plugs and particulate additive; and

cutting the continuous rod across the plugs of first filtering material.

Herein, the term "additive" includes additives such as activated carbon, zeolite, ion exchange resin, sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins and diatomaceous earths. One or more of the additives included in filters of the invention may also include a flavourant such as menthol.

The first filtering material and the second filtering material may be the same or different. The first filtering material and the second filtering material may (independently of each other) be, for example, cellulose acetate filtering material [e.g. a cellulose acetate tow (e.g. plasticised cellulose acetate tow)]; paper, e.g. filtration paper, e.g. filtration paper to which smoke modifying agent (e.g. flavour) has been applied; a non-woven web made from e.g. natural and/or synthetic fibres; a web or sheet derived from natural plant material(s); a bed of compressed or packed fibrous (natural and/or synthetic) material(s); and/or other fibre tow, for example polypropylene.

Preferably, the second filtering material includes an additive. Preferably the additive in the second filtering material is activated carbon, zeolite, or ion exchange resin (preferably a weakly basic anion exchange resin). The second filtering material may be for example cellulose acetate filtering material which includes activated carbon as additive.

Preferably the particulate additive (i.e. that within the spaces) is one or more of activated carbon, zeolite, or ion exchange resin. The present invention may provide a four-component filter including two (e.g. different) additives (the first in the "cavity", the space between the plug of second filtering material and one of the plugs of first filtering material; the other in an active acetate or similar plug of second filtering material), on a triple granular machine in a single pass. An example of a triple granular process is that known as Filtrona Cavitec, for example as described in European Patent Application No. 0278389.1.

The prior filter processes, if adapted for making four component filters, would require manufacture (including cutting) of dual filter rods in a first pass, and subsequent combination of dual filter rods in a subsequent second pass ("redualling a dual"); any such two pass process involving additive containing filters would require cutting across an additive containing component, and the attendant problems. As indicated above, the present invention may provide a manufacture of a four-component filter, e.g. a four component additive containing filter, in a single pass process. Clearly, manufacture in a single pass process provides significant advantages in terms of simplicity, speed and efficiency. Further, the filter may be applied to e.g. a cigarette without the need to cut through a component which contains an additive, reducing: (a) the attendant risk of contamination to the cigarette assembly process (or reclamation process); and also (b) reducing knife-wear during filter manufacture and cigarette manufacture (because additive containing components are more difficult to cut through).

The method of the invention has a further advantage that may reduce or eliminate the potential for variation in pressure drop of the product filters, especially under large-scale production conditions, if slight drifting of the configuration of the continuous rod with relation to the cutting apparatus occurs. Thus, a prior art triple granular filter, which includes two additives, will be cut across the upstream and downstream plugs, each of which may have a different pressure drop. Consistent performance of such product filters in terms of pressure drop is reliant on the cuts being in the correct place, so that upstream and downstream plus of correct length are present in the product filter. If slight drifting of the configuration of the continuous rod with relation to the cutting apparatus occurs the product filter may, for example, include an upstream plug which is too long and a downstream plug which is too short; the pressure drop of the product filter may be incorrect. With the method of the present invention, however, if slight drifting of the configuration of the continuous rod with relation to the cutting apparatus occurs, even if the cut might not be as desired, directly in the middle of the plug of first filter material which forms one end of the product filter, there will be a similar drift in the cut of the plug which forms the other end, so that if one plug is short the other will be long; there will always be the same length of first filter material within a filter, and the pressure drop will be more consistent.

Preferably the plugs are arranged into longitudinally spaced groups of three cylindrical plugs and single plugs of first filtering material using arranging means in the form of a collator drum.

Preferably, the longitudinally spaced groups of three cylindrical plugs and plugs of first filtering material are arranged on the filter wrapper material

(e.g. a ribbon of filter wrapper material) prior to application of particulate additive into the spaces. The longitudinally spaced groups of three cylindrical plugs and plugs of first filtering material are preferably arranged on top of the filter wrapper material, and the particulate additive placed (e.g. dropped using gravity from a supply) into the spaces; the edges of the filter wrapper material may then be wrapped up and around the cylindrical plugs and particulate additive to form a continuous rod of wrapped plugs and particulate additive.

Preferably the filter wrapper material is paper, e.g. air permeable paper.

The method of the invention is preferably a continuous in-line single pass procedure. The plugs of the first and second filtering materials may, for example, be fed (e.g. from hoppers such as are well known in the art) alternately at a constant spacing onto a continuously supplied and longitudinally advanced suction tape. The tape and plugs thereon are preferably continuously passed into and through arranging means in the form of a collator drum which arranges the plugs so as to provide, along the suction tape, alternating groups of three cylindrical plugs (comprising a plug of the first filtering material abutted at both ends with a plug of the second filtering material) longitudinally spaced from single plugs of the first material. Preferably, a longitudinally advancing ribbon of filter wrapper material is applied to the arranged plugs (e.g. longitudinally advancing from underneath the advancing plugs so the arranged plugs are arranged on top of the filter wrapper material), and particulate additive applied into (e.g. dropped into) the gaps formed by the longitudinal spacing between the groups of plugs and the single plugs. Preferably, the edges of the filter wrapper material are then wrapped and secured around (e.g. up and around) the cylindrical plugs and particulate additive to form a continuous rod of wrapped plugs and particulate additive. The ribbon and plugs (and particulate) thereon may be continuously passed into and through a garniture, which forms a continuous rod of plugs and particulate additive within the cylindrical wrapper, which wrapper is secured by a lapped and stuck seam.

The initial continuous rod as it issues continuously from the machine outlet is cut into finite lengths for subsequent use, the cuts being across the cylindrical plugs of the first filtering material. This cutting may be into individual filters (in which case a cut is made across each cylindrical plug of first filtering material), each of which is then attached to an individual wrapped tobacco rod to form a filter cigarette. More usually, however, the continuously issuing rod is first cut into double or higher multiple (usually quadruple or sextuple) lengths for subsequent use.

According to the present invention in a further aspect there is provided a tobacco smoke filter comprising downstream and upstream filtering plugs of a first filtering material; a further filtering plug of a second filtering material abutted to one of the downstream and upstream filtering plugs and longitudinally spaced from the other of the downstream and upstream filtering plugs; and a filter wrapper engaging around and joining the filtering plugs to define a cavity between the further filtering plug and the filtering plug from which it is longitudinally spaced. Preferably the filter includes particulate additive within the cavity. According to the present invention in a still further aspect there is provided a multiple filter rod comprising a plurality (e.g. 2, 4 or 6) of filters of the invention integrally joined end-to-end in mirror image relationship.

Preferably, the first filtering material is made of bonded filamentary tow, for example filamentary cellulose acetate tow. This material is of white or off- white colour and does not include particulate additive. Cuts, during filter or filter cigarette manufacture, across the filter plugs of this material (which does not include particulate additive) form a clean, e.g. white, end appearance at both ends of the filter.

Preferably, the cylindrical plugs of a first filtering material comprise preformed WA (wrapped acetate) filter plugs, as are well known in the art. The cylindrical plugs of a first filtering material may comprise NWA (non-wrapped acetate) filtering plugs - made, for example, as described in GB-A-1 ,169,932. Pre-formed wrapped filter plugs (e.g. of filamentary cellulose acetate tow) are preferred. However, other fibrous and non-fibrous cylindrical plugs of a first filtering material can be used (e.g. a plug of staple fibres or cellular plastics material or a plug of plastics - e.g. HDPE - fibres or filaments).

Preferably, the second filtering material includes an additive, such as activated carbon, zeolite, ion exchange resin, sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins or diatomaceous earths.

Preferably the additive in the second filtering material is activated carbon, zeolite, or ion exchange resin (preferably a weakly basic anion exchange resin). Preferably, the second filtering material is in the form of a cellulose acetate plug - e.g. cellulose acetate tow - which is combined with particles of additive such as carbon, e.g. particles, preferably granules, of activated carbon.

For example, the cylindrical plug of second filtering material may preferably comprise a plug of cellulose acetate which includes particles, especially granules, of activated carbon which are carried on the cellulose acetate tow of filaments or fibres or sheet material which forms the plug. Cellulose acetate tow impregnated with activated carbon in this way is well known in the art, and is often referred to as "active acetate".

Preferably the particulate additive within the cavity is an additive such as activated carbon, zeolite, ion exchange resin, sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins or diatomaceous earths. Preferably, the additive within the cavity is an ion exchange resin (more preferably a weakly basic anion exchange resin). The additive within the cavity may comprise other materials such as (e.g. granules) of activated carbon, or zeolite.

In a filter cigarette according to the invention a filter is joined to a wrapped tobacco rod with one end 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 filter and rod to leave much of the filter wrapper exposed) or by a full tipping overwrap (which engages around the full filter length and the adjacent end of the rod). Any filter or filter cigarette according to the invention may be ventilated by methods well known in the art, e.g. by use of a pre-perforated or air permeable plug wrap, and/or laser perforation of plugwrap and tipping overwrap. 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 cavity; ventilation upstream of and/or in register with the cavity is frequently preferred.

According to the present invention in a still further aspect there is provided a method of producing a filter cigarette comprising a step of attaching a wrapped tobacco rod to a filter or multiple filter rod as described above or herein. According to the present invention in a still further aspect there is provided a method of producing a filter cigarette comprising a step of attaching a wrapped tobacco rod to multiple component filter or multiple filter rod produced by any method described above or herein. According to the present invention in a still further aspect there is provided a method of producing a multi-component filter or multiple component filter rod comprising the steps of:

arranging cylindrical plugs of a first filtering material, a second filtering material and a third filtering material so as to provide alternating first and second groups of plugs with each first group of plugs longitudinally spaced at each end from a second group of plugs; the first groups comprising a plug of first filtering material abutted at either end with a plug of second filtering material, each plug of second filtering material optionally abutting a plug of third filtering material at the other e.g. opposite end to the plug of first filtering material; and each second group of plugs comprising a plug of first filtering material optionally abutted at either end with a plug of third filtering material;

introducing a particulate additive into the space between each first group of plugs and each second group of plugs;

applying a filter wrapper material around the groups of plugs and particulate additive to form a continuous rod of wrapped plugs and particulate additive; and

cutting the continuous rod across the plugs of first filtering material.

In one example, each first group of plugs may comprise a plug of first filtering material abutted at either end with a plug of second filtering material; and each second group of plugs may comprise a plug of first filtering material abutted at either end with a plug of third filtering material. In another example each first group of plugs may comprise five plugs - a plug of first filtering material abutted at either end with a plug of second filtering material, each plug of second filtering material abutting a plug of third filtering material at the other e.g. opposite end to the plug of first filtering material; and each second group of plugs may comprise a plug of first filtering material.

The plugs of filtering material may be arranged e.g. symmetrically about a point half way along each plug of first filtering material (e.g. at the point where the continuous rod is to be cut). For example the plugs of filtering material may be arranged so that the uncut rod may be thought of as a continuous row of adjoining filter tips (each having one end half way through a plug of first filtering material and the other end half way through the next plug of first filtering material in the continuous rod), such that each filter tip is the mirror image of the tips adjoining it. These and similar arrangements may allow the product rod/filters to be compatible with standard equipment and methodology for attaching filter tips to tobacco rod columns in cigarette manufacture.

The plugs of filtering material may be arranged into longitudinally spaced first and second groups of plugs using arranging means in the form of a collator drum.

The plugs of filtering material may be arranged on the filter wrapper material prior to application of particulate additive into the spaces. The plugs of filtering material may be arranged on top of the filter wrapper material; particulate additive placed into the spaces; and the edges of the filter wrapper material then wrapped up and secured around the plugs and particulate additive to form a continuous rod of wrapped plugs and particulate additive.

For production of a filter or filter element of circumference about 25mm, typical measurements may be as follows. The plugs of first filtering material may be of length e.g. between 8 and 12mm, for example, 9, 10, 11mm. Each plug of second and third filtering material may be, for example, of length between 7.5mm and 9mm, e.g. 8mm. The space between each first group of plugs and each second group of plugs - i.e. the length of the particulate additive portion of the filter or filter element - may, for example, be of length between 3 and 5mm, e.g. 4mm. The overall length of the filter may, for example, be between 30 and 35mm, for example 30mm, 31mm etc.

The first filtering material and the second filtering material and the third material may be different to each other (three different filtering materials); may all be the same; or two of the first, second and third materials may be the same filtering material while the other is different. The first filtering material and the second filtering material and the third filtering material may (independently of each other) be, for example, cellulose acetate filtering material [e.g. a cellulose acetate tow (e.g. plasticised cellulose acetate tow)]; paper, e.g. filtration paper, e.g. filtration paper to which smoke modifying agent (e.g. flavour) has been applied; a non-woven web made from e.g. natural and/or synthetic fibres; a web or sheet derived from natural plant material(s); a bed of compressed or packed fibrous (natural and/or synthetic) material(s); and/or other fibre tow, for example polypropylene.

The first filtering material may be bonded filamentary tow, for example filamentary cellulose acetate tow. This material is of white or off-white colour and does not include particulate additive. Cuts, during filter or filter cigarette manufacture, across the filter plugs of this material form a clean, e.g. white, end appearance at both ends of the filter. The first filtering material may be, for example, preformed WA (wrapped acetate) filter plugs, NWA (non-wrapped acetate) filtering plugs, or plugs of other fibrous and non-fibrous material (e.g. staple fibres, cellular plastics material, plastics - e.g. HDPE - fibres or filaments etc.), as discussed with reference to the four segment filter above.

The second and third filtering materials may be the same, or different. The second and third filtering materials may be made of the same material as the first filtering material (e.g bonded filamentary tow), and may include additive. The second filtering material may include an additive such as activated carbon, zeolite, ion exchange resin, sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins or diatomaceous earths. The third filtering material may include an additive such as activated carbon, zeolite, ion exchange resin, sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins or diatomaceous earths. The second and third filtering materials may include an additive, wherein the second filtering material includes a different additive to the third filtering material. The second and/or third filtering materials may be in the form of a cellulose acetate plug - e.g. cellulose acetate tow - which is combined with particles of additive such as carbon, e.g. particles, preferably granules, of activated carbon, or e.g. particles, preferably granules, of ion exchange resin. For example, the cylindrical plug of second filtering material may preferably comprise a plug of cellulose acetate which includes particles, especially granules, of activated carbon which are carried on the cellulose acetate tow of filaments or fibres or sheet material which forms the plug. Cellulose acetate tow impregnated with activated carbon in this way is well known in the art, and is often referred to as "active acetate".

The particulate additive in the space between each group of plugs may be one or more of activated carbon, zeolite, ion exchange resin, sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins or diatomaceous earths.

In one aspect, the present invention may provide a five-component filter including two or more (e.g 3, e.g. different) additives (the first in the "cavity", the space between the groups of plugs; the other(s) in an active acetate or similar plug(s) of second and/or third filtering material), in a single pass. As discussed above with reference to four segment filters, manufacture in a single pass process provides significant advantages in terms of simplicity, speed and efficiency. Further, the filter may be applied to e.g. a cigarette without the need to cut through a component which contains an additive, reducing: (a) the attendant risk of contamination to the cigarette assembly process (or reclamation process); and also (b) reducing knife-wear during filter manufacture and cigarette manufacture (because additive containing components are more difficult to cut through). Further, as also discussed with reference to four segment filters, the methods of the invention have a further advantage that they may reduce or eliminate the potential for variation in pressure drop of the product filters, especially under large-scale production conditions, if slight drifting of the configuration of the continuous rod with relation to the cutting apparatus occurs (see above).

According to the present invention in a still further aspect there is provided a tobacco smoke filter comprising downstream and upstream filtering plugs of a first filtering material; a plug of a second filtering material abutted to one of the downstream and upstream filtering plugs; a plug of third filtering material abutted to the other of the downstream and upstream filtering plugs and longitudinally spaced from the plug of second filtering material; and a filter wrapper engaging around and joining the plugs to define a cavity between the plug of second filtering material and the plug of third filtering material from which it is longitudinally spaced; the filter including particulate additive within the cavity.

According to the present invention in a still further aspect there is provided a tobacco smoke filter comprising downstream and upstream filtering plugs of a first filtering material; a plug of a second filtering material abutted to one of the downstream and upstream filtering plugs; a plug of third filtering material abutted to the plug of second filtering material and longitudinally spaced from the downstream or upstream filtering plug of first filtering material to which the plug of second filtering material is not abutted; and a filter wrapper engaging around and joining the plugs to define a cavity between the plug of third filtering material and the plug of first filtering material from which it is longitudinally spaced; the filter including particulate additive within the cavity.

For a filter of circumference about 25mm, typical measurements may be as follows. The downstream and upstream plugs of first filtering material may be e.g. between 4 and 6mm, for example, 4.5, 5, 5.5mm, long. Each plug of second and third filtering material may be, for example, of length between

7.5mm and 9mm, e.g. 8mm. The space between each first group of plugs and each second group of plugs - i.e. the length of the particulate additive portion of the filter or filter element - may, for example, be of length between 3 and

5mm, e.g. 4mm. The overall length of the filter may, for example, be between

30 and 35mm, for example 30mm, 31 mm etc.

The first filtering material may be bonded filamentary tow, for example filamentary cellulose acetate tow, as discussed above. The plug(s) of first filtering material may be, for example, preformed WA (wrapped acetate) filter plugs, NWA (non-wrapped acetate) filtering plugs, or plugs of other fibrous and non-fibrous material (e.g. staple fibres, cellular plastics material, plastics - e.g. HDPE - fibres or filaments etc.), as discussed with reference to the four segment filter above. The second and third filtering materials may be the same, or different. The second and third filtering materials may be made of the same material as the first filtering material (e.g bonded filamentary tow), and may include additive. The second filtering material may includes an additive such as activated carbon, zeolite, ion exchange resin, sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins or diatomaceous earths. The third filtering material may include an additive such as activated carbon, zeolite, ion exchange resin, sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins or diatomaceous earths. The second and third filtering materials may include an additive, wherein the second filtering material includes a different additive to the third filtering material. The second and/or third filtering materials may be in the form of a cellulose acetate plug - e.g. cellulose acetate tow - which is combined with particles of additive such as carbon, e.g. particles, preferably granules, of activated carbon, or particles, preferably granules, of ion exchange resin.

The particulate additive within the cavity may be one or more of activated carbon, zeolite, ion exchange resin, sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins or diatomaceous earths.

The present invention will now be illustrated by way of example with reference to the accompanying drawings, in which:

FIGURE 1 shows a schematic sectional side elevation view, not to scale, of a triple granular filter of the prior art containing two additives (one in the cavity, one in the tobacco end component);

FIGURE 2 shows a schematic sectional side elevation view, not to scale, of a filter according to one embodiment of the invention;

FIGURES 3 and 3a show a schematic view of a production line for making filters according to embodiments of the invention (e.g. those of Figure 2); FIGURE 4 is a schematic sectional side elevation view, not to scale, of a multiple length rod of the filters of Figure 2 showing how it may be cut to form multiple and eventually individual filter lengths according to the invention;

FIGURE 5 is a schematic sectional side elevation view, not to scale, of a multiple length rod of five segment filters according to an example of a further aspect of the invention, showing how it may be cut to form multiple and eventually individual filter lengths according to an example of a further aspect of the invention; and

FIGURE 6 is a schematic sectional side elevation view, not to scale, of a different multiple length rod of five segment filters according to an example of a further aspect of the invention, showing how it may be cut to form multiple and eventually individual filter lengths according to an example of a further aspect of the invention.

The Figure 1 prior art triple granular filter has a cylindrical downstream or buccal end filtering plug 102 of filtering material in the form of a wrapped cellulose acetate plug, a cylindrical upstream (tobacco end) filtering plug 103 of active acetate material, the plugs 102 and 103 being longitudinally spaced from each other. A filter wrapper 105 of air-permeable paper is engaged around the plugs to form a cavity 106 between the downstream plug 102 and the upstream plug 103. Particulate additive in the form of granules of active carbon 107 is located in the cavity 106. The prior art triple granular filters can provide problems, as follows. These filters are provided in continuous rods of double or higher multiple (usually quadruple or sextuple) filter lengths, the multiple length filter rods being cut during the process of application to tobacco rods to form filter cigarettes. As will be generally understood, cutting across rods of active acetate or similar material to form the tobacco end filter plug 103 requires cutting through a plug which includes an additive, with the attendant risk of contamination to the cigarette assembly process, and also the risk of contamination of the tobacco, which may be important if the tobacco has to be reclaimed. The Figure 2 filter 1 is 27mm long and has a circumference of around 25mm. It has a cylindrical downstream (buccal end) filtering plug 2 of first filtering material in the form of a wrapped cellulose acetate plug of length 7mm and circumference of around 25mm, a cylindrical upstream (tobacco end) filtering plug 3 of the same filtering material, also in the form of a wrapped cellulose acetate plug of length 7mm and circumference of around 25mm; and further filtering plug 4 of a second filtering material in the form of an active acetate plug of length 10mm and circumference of around 25mm. The upstream end of further filtering plug 4 is abutted to the downstream end of the upstream filtering plug 3 and longitudinally spaced from the downstream filtering plug 2. A filter wrapper 5 of air permeable paper is engaged around the plugs to form a cavity 6 between further filtering plug 4 and downstream filtering plug 2. Particulate additive 7 in the form of particles of ion exchange resin is located in the cavity. It will be appreciated that, for example, other particle additive materials 7 may be used, and/or the position of cavity 6 and the further filtering plug 4 may be reversed so plug 4 is abutted to filtering plug 2 and longitudinally spaced from filtering plug 3 (and cavity 6 is formed between filtering plug 4 and filtering plug 3).

In the illustrated embodiment, the upstream and downstream filtering plugs 2, 3 are wrapped plugs of filamentary cellulose acetate tow. However, it will be appreciated that NWA (non-wrapped acetate) filtering plugs which are well known in the art - made, for example, as described in GB-A-1 ,169,932 (and other materials) - may be used for plugs 2, 3.

It will be appreciated that filter 1 of the Figure 2 type may be included in a filter cigarette by methods which are well known in the art. For example, it may be joined at its upstream end 8 to a tobacco rod in its own wrap (not shown) by means of a full tipping overwrap (also not shown) which surrounds and engages the full length of the filter and the adjacent end only of the wrapped tobacco rod.

FIGURES 3 and 3a show a schematic view of a production line in a further embodiment of the invention for making filters according to embodiments of the invention (e.g. those of Figure 2) by means of a continuous in-line single pass procedure. The filters may be made using an adaptation of a machine for making triple granular filters; such machines are well known in the art.

In Figure 3, a first hopper delivery wheel 11 (which is attached to a hopper which is not shown) provides a supply of plugs 14 of a second filtering material in the form of active acetate plugs of length 10mm and circumference of around 25mm. These correspond to plug 4 in the embodiment of Fig 1. Second hopper delivery wheel 21 (which is attached to a second hopper which is also not shown) provides a supply of plugs 22 of first filtering material in the form of a wrapped cellulose acetate plugs of length 14 mm. The plugs 22 form, in the completed filter of Filter 1 , the cylindrical downstream (buccal end) filtering plug 2 of first filtering material and cylindrical upstream (tobacco end) filtering plug 3 of the same filtering material. Hopper delivery wheels 11 , 21 , hoppers, and the methods of providing these with cut lengths of plugs 14, 22, are well known in the art. The plugs 14, 22 of the first and second filtering materials are fed from hopper delivery wheels 11 , 21 alternately at constant spacing onto a continuously supplied and longitudinally advancing suction tape 23, which is advancing in the direction shown by arrows 400. The tape 23 and plugs 14, 22 thereon are preferably continuously passed into and through arranging means in the form of a collator drum 24 which arranges the plugs 14, 22 so as to provide, along the suction tape, alternating groups of three cylindrical plugs 31 (comprising a plug 22 of the first filtering material abutted at both ends with a plug 14 of the second filtering material) longitudinally spaced from single plugs 22 of the first material. The collator drum rotates and, as it does so, vanes on its surface bring plugs 14, 22 together to form groups 31 and introduce a defined spacing between each end of group 31 and each plug 14. A supply of longitudinally advancing ribbon of filter wrapper material 45 is applied from underneath the advancing arranged groups of plugs 31 and plugs 22 as these exit the collator drum 24, so the arranged groups of plugs 31 and plugs 22 are arranged on top of the filter wrapper material 45, and particulate additive 46 dropped from a supply 47 into the gaps formed by the longitudinal spacing between the groups of plugs 31 and the single plugs 22. The ribbon 45 and groups of plugs 31 and plugs 22 (and particulate additive 46) thereon are continuously passed into and through a garniture 49 (shown partially), which forms a continuous rod 51 of plugs and particulate additive within the cylindrical wrapper, which wrapper is secured by a lapped and stuck seam (see Fig 3a).

The initial continuous rod 51 as it issues continuously from the machine outlet is cut into finite lengths for subsequent use, the cuts being made using devices and blades which are well known in the art, and being made across the cylindrical plugs 22 of the first filtering material. This cutting may be into individual filters (in which case a cut is made across each cylindrical plug or first material), each of which is then attached to an individual wrapped tobacco rod to form a filter cigarette. More usually, however, the continuously issuing rod 51 is first cut into double or higher multiple (usually quadruple or sextuple) lengths for subsequent use; when the initial cut is into quadruple or higher lengths, then the latter are subsequently cut into double lengths for the filter cigarette assembly - in which the double length filter rod is assembled and joined (by ring tipping or full tipping overwrap) between a pair of wrapped tobacco rods with the combination then being severed centrally to give two individual filter cigarettes. For this purpose in the present invention the filter plugs of the first filtering material in the initial continuously produced rod are double the lengths of the plugs of the first filtering material in the eventual individual filters. The continuous rod and the multiple lengths cut from it have individual filters according to the invention integrally joined end-to-end in mirror image relationship, and the double length rod for the mentioned filter cigarette assembly has a double length downstream plug between opposed single length plugs and single length cavities closed at their distal ends by respective single length upstream plugs, the cut to make the individual filter cigarettes being made laterally midway through the central double length plug to form two downstream plugs. The invention includes the described production procedure and the double and higher multiple length filter rods made thereby.

Figure 4 shows a quadruple length multiple filter rod 300 of filters of the embodiment of Figure 2 as may be provided by the method shown in Figure 3. The rod 300 includes plugs 22 of first filtering material of length 14 mm, plugs 14 of second filtering material of length 10 mm, filled cavities 301 - filled with particulate additive - of length 3 mm, and, at each end of the multiple length rod a plug of first filtering material 2 of length 7 mm. The complete multiple length rod 300 includes four filters of the embodiment of Figure 2 integrally joined end-to-end in mirror image relationship, and has length 108 mm; it may be known as a "four up 108 mm" multiple length rod. During the cigarette manufacturing process (using techniques which are well known in the art and briefly described above) the multiple length rod 300 is, in accordance with an embodiment of the invention, cut in the areas shown by arrows 305 through plugs 22 to give four filters each configured with a plug of first filtering material of length 7 mm at each end and a plug of second filtering material 14 and filled cavity 303 between the plugs 7. It will be appreciated that the cuts are made across the first filtering material (which does not include additive) and the risk of contamination is greatly reduced.

Figure 5 shows a quadruple length multiple filter rod 400 of five segment filters, according to an example of the invention in another aspect. Each filter (when cut from the quadruple length rod) includes downstream and upstream filtering plugs of length 5mm made up of a first filtering material in the form of cellulose acetate. An 8mm long plug 423 of a second filtering material ) (an active acetate-type segment made up of cellulose acetate tow loaded with particulate additive in the form of ion exchange resin in place of activated carbon) is abutted to the downstream filtering plug, and longitudinally spaced by a distance of 4mm from an 8mm long plug 424 of third filtering material (an active acetate plug containing activated carbon, as is well known in the art which is abutted to the upstream filtering plug. A filter wrapper is engaged around and joins the plugs to define a cavity of length 4mm between the plug of second filtering material and the plug of third filtering material from which it is longitudinally spaced; the filter includes particulate additive in the form of activated carbon within the cavity.

Thus, complete multiple length rod 400 includes four five segment filters as described above integrally joined end-to-end in mirror image relationship, and has length 120 mm; it may be known as a "four up 120 mm" multiple length rod. During the cigarette manufacturing process (using techniques which are well known in the art and briefly described above and below), the multiple length rod 400 is, in accordance with an embodiment of the invention, cut in the areas shown by arrows 405 through plugs 422 to give four filters each configured with a plug of first filtering material of length 5 mm at each end; a plug of second filtering material 423 of length 8mm; a filled cavity 401 ; and a plug of third filtering material 424 of length 8mm between the plugs. It will be appreciated that the cuts 405 are made across the first filtering material (which does not include additive) and the risk of contamination is greatly reduced.

It will be appreciated that the multiple filter rod of Figure 5 may be made by an adaptation of the method described with reference to Fig 3, with a third hopper delivery wheel added to deliver the plugs of third filtering material, and further adaptation of e.g. the collator wheel. Thus a first hopper delivery wheel provides a supply of plugs 423 of a second filtering material (active acetate plugs containing ion exchange resin) of length 8mm and circumference of around 25mm. A second hopper delivery wheel provides a supply of plugs 422 of first filtering material in the form of a wrapped cellulose acetate plugs of length 10 mm, which will form in the completed filter, the cylindrical downstream (buccal end) filtering plug (5mm long) of first filtering material and cylindrical upstream (tobacco end) filtering plug (5mm long) of the same filtering material. A third hopper delivery wheel provides a supply of plugs 424 of a third filtering material in the form of active acetate plugs, of length 8mm and circumference of around 25mm. The plugs 422, 423, 424 of the first, second and third filtering materials are fed from the hopper delivery wheels at constant spacing onto a continuously supplied and longitudinally advancing suction tape in the following order: plug 423 of second filtering material, plug 422 of first filtering material and plug 423 of second filtering material (i.e. the components of a first group of plugs); followed by plug 424 of third filtering material, plug 422 of first filtering material and plug 424 of third filtering material (the components of a second group of plugs), followed by the components of a further first group of plugs, then the components of a further second group of plugs, and so on. The tape and plugs thereon are continuously passed into and through arranging means in the form of a collator drum which arranges the plugs so as to provide, along the suction tape, alternating first and second groups of abutted plugs with each first group of abutted plugs longitudinally spaced at each end from a second group of abutted plugs. Each first group of plugs comprises a plug 422 of first filtering material abutted at either end with a plug 423 of second filtering material, and each second group of plugs comprises a plug 422 of first filtering material abutted at either end with a plug 424 of third filtering material. The collator drum rotates and, as it does so, vanes on its surface bring the plugs together to form the groups described above and introduce a defined spacing of 4mm between each group. A supply of longitudinally advancing ribbon of filter wrapper material is applied from underneath the advancing arranged groups of plugs as these exit the collator drum, so the arranged groups of plugs are arranged on top of the filter wrapper material, and particulate additive in the form of activated carbon is dropped, from a supply, into the gaps formed by the longitudinal spacing between the groups of plugs. The ribbon and groups of plugs (and particulate additive) thereon are continuously passed into and through a garniture which forms a continuous rod of plugs and particulate additive within the cylindrical wrapper, which wrapper is secured by a lapped and stuck seam. The initial continuous rod as it issues continuously from the machine outlet is cut into finite lengths for subsequent use, the cuts being made using devices and blades which are well known in the art, and being made across the cylindrical plugs of the first filtering material.

Figure 6 shows a quadruple length multiple filter rod 400' of five segment filters, according to a further example of the invention in another aspect. Each filter (when cut from the quadruple length rod) includes downstream and upstream filtering plugs of length 5mm made up of a first filtering material in the form of cellulose acetate. An 8mm long plug 424' of third filtering material (an active acetate plug containing activated carbon, as is well known in the art) is abutted to the upstream filtering plug, and abutted at its other end to an 8mm long plug 423' of a second filtering material (an active acetate-type segment made up of cellulose acetate tow loaded with particulate additive in the form of ion exchange resin in place of activated carbon). Plug 423' is longitudinally spaced by a distance of 4mm from the downstream filtering plug. A filter wrapper is engaged around and joins the plugs to define a cavity of length 4mm between the plug of second filtering material and the downstream filtering plug from which it is longitudinally spaced; the filter includes particulate additive in the form of activated carbon within the cavity.

Thus, complete multiple length rod 400' includes four five segment filters as described above integrally joined end-to-end in mirror image relationship, and has length 120 mm; it may be known as a "four up 120 mm" multiple length rod. During the cigarette manufacturing process (using techniques which are well known in the art and briefly described above and below), the multiple length rod 400' is, in accordance with an embodiment of the invention, cut in the areas shown by arrows 405' through plugs 422' to give four filters each configured with a plug of first filtering material of length 5 mm at each end; a filled cavity 401' of 4mm length next to one of these plugs; a plug of second filtering material 423' of length 8mm next to the filled cavity; and a plug of third filtering material 424' of length 8mm between the plug of second filtering material 423' next to the other plug of first filtering material of length 5 mm. It will be appreciated that the cuts 405' are made across the first filtering material (which does not include additive) and the risk of contamination is greatly reduced. It will be appreciated that the multiple filter rod of Figure 6 may be made by a further adaptation of the method described with reference to Fig 3 (and Fig 5).

Claims

1. A method of producing a multi-component filter or multiple component filter rod comprising the steps of:

arranging alternating cylindrical plugs of a first filtering material and a second filtering material so as to provide groups of three plugs comprising a plug of first filtering material abutted at either end with a plug of second filtering material, each such group longitudinally spaced at each end from a plug of first filtering material;

introducing a particulate additive into the space between each group of three plugs and each single plug;

cutting the continuous rod across the plugs of first filtering material.

2. A method according to claim 1 in which the plugs are arranged into longitudinally spaced groups of three cylindrical plugs and plugs of first filtering material using arranging means in the form of a collator drum.

3. A method according to claim 1 or claim 2 in which the longitudinally spaced groups of three cylindrical plugs and plugs of first filtering material are arranged on the filter wrapper material prior to application of particulate additive into the spaces.

4. A method according to any preceding claim in which the longitudinally spaced groups of three cylindrical plugs and plugs of first filtering material are arranged on top of the filter wrapper material; particulate additive is placed into the spaces; and the edges of the filter wrapper material are wrapped up and secured around the cylindrical plugs and particulate additive to form a continuous rod of wrapped plugs and particulate additive.

5. A method according to any preceding claim in which the first filtering material is bonded filamentary tow, for example filamentary cellulose acetate tow.

6. A method according to any preceding claim in which the second filtering material includes an additive such as activated carbon, zeolite, ion exchange resin, sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins or diatomaceous earths.

7. A method according to any preceding claim in which the particulate additive in the space between each group of three plugs and each single plug is one or more of activated carbon, zeolite, ion exchange resin, sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins and diatomaceous earths.

8. A tobacco smoke filter comprising downstream and upstream filtering plugs of a first filtering material; a further filtering plug of a second filtering material abutted to one of the downstream and upstream filtering plugs and longitudinally spaced from the other of the downstream and upstream filtering plugs; and a filter wrapper engaging around and joining the filtering plugs to define a cavity between the further filtering plug and the filtering plug from which it is longitudinally spaced; the filter including particulate additive within the cavity.

9. A filter according to claim 8 wherein the first filtering material is bonded filamentary tow, for example filamentary cellulose acetate tow.

10. A filter according to claim 8 or 9 wherein the second filtering material includes an additive such as activated carbon, zeolite, ion exchange resin, sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins or diatomaceous earths.

11. A filter according to claim 8, 9 or 10 wherein the particulate additive within the cavity is one or more of activated carbon, zeolite, ion exchange resin, sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins or diatomaceous earths.

12. A multiple filter rod comprising a plurality of filters according to any of claims 8 to 11 integrally joined end-to-end in a mirror image relationship.

13. A filter cigarette comprising a wrapped tobacco rod and a filter according to any of claims 8 to 11.

14. A filter cigarette comprising a wrapped tobacco rod and a filter made by a method according to any of claims 1 to 7.

5 15. A method of producing a filter cigarette comprising a step of attaching a wrapped tobacco rod to a filter according to any of claims 8 to 11 or a multiple filter rod according to claim 12.

16. A method of producing a filter cigarette comprising a step of attaching a wrapped tobacco rod to multiple component filter or multiple filter rod produced

-10 by a method according to any of claims 1 to 7.

17. A tobacco smoke filter substantially as hereinbefore described with reference to Fig 2 of the attached drawings.

18. A multiple filter rod substantially as hereinbefore described with reference to 15 Fig 4 of the attached drawings.

19. A method of producing a multi-component filter or multiple component filter rod substantially as hereinbefore described with reference to Figs 3 and 3a of the attached drawings.

20

20. A method of producing a multi-component filter or multiple component filter rod comprising the steps of:

arranging cylindrical plugs of a first filtering material, a second filtering material and a third filtering material so as to provide alternating first and second

25 groups of plugs with each first group of plugs longitudinally spaced at each end from a second group of plugs; the first groups comprising a plug of first filtering material abutted at either end with a plug of second filtering material, each plug of second filtering material optionally abutting a plug of third filtering material at the other end to the plug of first filtering material; and each second group of plugs

30 comprising a plug of first filtering material optionally abutted at either end with a plug of third filtering material; introducing a particulate additive into the space between each first group of plugs and each second group of plugs;

cutting the continuous rod across the plugs of first filtering material.

21. A method according to claim 20 in which each first group of plugs comprises a plug of first filtering material abutted at either end with a plug of second filtering material; and each second group of plugs comprises a plug of first filtering material abutted at either end with a plug of third filtering material.

22. A method according to claim 20 in which each first group of plugs comprises a plug of first filtering material abutted at either end with a plug of second filtering material, each plug of second filtering material abutting a plug of third filtering material at the other end to the plug of first filtering material; and each second group of plugs comprises a plug of first filtering material.

23. A method according to claim 20, 21 or 22 in which the plugs of filtering material are arranged into longitudinally spaced first and second groups of plugs using arranging means in the form of a collator drum.

24. A method according to any of claims 20 to 23 in which the longitudinally spaced first and second groups of plugs are arranged on the filter wrapper material prior to application of particulate additive into the spaces.

25. A method according to any of claims 20 to 24 in which the longitudinally spaced first and second groups of plugs are arranged on top of the filter wrapper material; particulate additive is placed into the spaces; and the edges of the filter wrapper material are wrapped up and secured around the plugs and particulate additive to form a continuous rod of wrapped plugs and particulate additive.

26. A method according to any of claims 20 to 25 in which the first filtering material is bonded filamentary tow, for example filamentary cellulose acetate tow.

27. A method according to any of claims 20 to 26 in which the second filtering material includes one or more additives selected from activated carbon, zeolite, ion exchange resin, sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins and diatomaceous earths, and/or in which the third filtering material includes one or more additives selected from activated carbon, zeolite, ion exchange resin, sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins and diatomaceous earths.

28. A method according to any of claims 20 to 27 in which the second and third filtering materials includes additive, and the second filtering material includes a different additive to the third filtering material.

29. A method according to any of claims 20 to 28 in which the particulate additive in the space between each group of plugs is one or more of activated carbon, zeolite, ion exchange resin, sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins and diatomaceous earths.

30. A tobacco smoke filter comprising downstream and upstream filtering plugs of a first filtering material; a plug of a second filtering material abutted to one of the downstream and upstream filtering plugs; a plug of third filtering material abutted to the other of the downstream and upstream filtering plugs and longitudinally spaced from the plug of second filtering material; and a filter wrapper engaging around and joining the plugs to define a cavity between the plug of second filtering material and the plug of third filtering material from which it is longitudinally spaced; the filter including particulate additive within the cavity.

31. A tobacco smoke filter comprising downstream and upstream filtering plugs of a first filtering material; a plug of a second filtering material abutted to one of the downstream and upstream filtering plugs; a plug of third filtering material abutted to the plug of second filtering material and longitudinally spaced from the downstream or upstream filtering plug of first filtering material to which the plug of second filtering material is not abutted; and a filter wrapper engaging around and joining the plugs to define a cavity between the plug of third filtering material and the plug of first filtering material from which it is longitudinally spaced; the filter including particulate additive within the cavity.

32. A filter according to claim 30 or 31 wherein the first filtering material is bonded filamentary tow, for example filamentary cellulose acetate tow.

33. A filter according to any of claims 30, 31 or 32 wherein the second filtering material includes one or more additives selected from activated carbon, zeolite, ion exchange resin, sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins and diatomaceous earths and/or the third filtering material includes one or more additives selected from activated carbon, zeolite, ion exchange resin, sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins and diatomaceous earths.

34. A filter according to any of claims 30 to 33 wherein the second and third filtering materials includes additive, and the second filtering material includes a different additive to the third filtering material.

35. A filter according to any of claims 30 to 34 wherein the particulate additive within the cavity is one or more of activated carbon, zeolite, ion exchange resin, sepiolite, silica gel, alumina, molecular sieves, carbonaceous polymer resins and diatomaceous earths.

36. A multiple filter rod comprising a plurality of filters according to any of claims 30 to 35 integrally joined end-to-end in a mirror image relationship.

37. A filter cigarette comprising a wrapped tobacco rod and a filter according to any of claims 30 to 35.

38. A filter cigarette comprising a wrapped tobacco rod and a filter made by a method according to any of claims 20 to 29.

39. A method of producing a filter cigarette comprising a step of attaching a wrapped tobacco rod to a filter according to any of claims 30 to 35 or a multiple filter rod according to claim 36.

40. A method of producing a filter cigarette comprising a step of attaching a wrapped tobacco rod to a multiple component filter or multiple filter rod produced by a method according to any of claims 20 to 29.

41. A multiple filter rod substantially as hereinbefore described with reference to Fig 5 or Fig 6 of the attached drawings.

42. A method of producing a multi-component filter or multiple component filter rod substantially as hereinbefore described with reference to Figs 5 or Fig 6 of the attached drawings.

43. A method according to any of claims 1 to 7 or a filter according to any of claims 8 to 11 , in which the first filtering material and the second filtering material are the same or different and are selected from cellulose acetate filtering material; paper; a non-woven web made from e.g. natural and/or synthetic fibres; a web or sheet derived from natural plant material(s); a bed of compressed or packed fibrous (natural and/or synthetic) material(s); and other fibre tow.

44. A method according to any of claims 20 to 29 or a filter according to any of claims 30 to 35, in which the first filtering material and the second filtering material and the third filtering material are the same or different and are selected from cellulose acetate filtering material; paper; a non-woven web made from e.g. natural and/or synthetic fibres; a web or sheet derived from natural plant material(s); a bed of compressed or packed fibrous (natural and/or synthetic) material(s); and other fibre tow.

45. A multiple filter rod comprising a plurality of filters according to any of claims 43 or 44 integrally joined end-to-end in a mirror image relationship.

46. A filter cigarette comprising a wrapped tobacco rod and a filter according to any of claims 43 or 44, or a filter made by a method according to any of claims 43 or 44.

47. A method of producing a filter cigarette comprising a step of attaching a wrapped tobacco rod to a filter according to any of claims 43 or 44 or a multiple filter rod according to claim 45.