EP2866595A1

EP2866595A1 - Tobacco smoke filter

Info

Publication number: EP2866595A1
Application number: EP13732893.6A
Authority: EP
Inventors: Eko SUBAKTI; Andri SUROSO; Sudirman WIDIARTO
Original assignee: Essentra Filter Products Development Co Pte Ltd
Current assignee: Essentra Filter Products Development Co Pte Ltd
Priority date: 2012-06-27
Filing date: 2013-06-26
Publication date: 2015-05-06
Anticipated expiration: 2033-06-26
Also published as: GB201211523D0; LT2866595T; PL2866595T3; HUE045905T2; RU2014153260A; WO2014001388A1; EP2866595B1; RU2629869C2

Abstract

There is disclosed a tobacco smoke filter or filter element comprising: a wrapper engaged around a longitudinally extending core of tobacco smoke filtering material, wherein a first end of the wrapper is substantially flush with a first end of the core around which it is engaged, and a second end of the wrapper extends beyond a second end of the core around which is engaged to define a cavity at the second end of the filter or filter element; and an adhesive disposed between the wrapper and the core, wherein the adhesive is not disposed on the portion of the wrapper which extends beyond the second end of the core around which it is engaged to define the cavity.

Description

TOBACCO SMOKE FILTER

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

Recess filters are well known in the tobacco industry and provide a distinctive end appearance for cigarettes. They are typically manufactured by wrapping a continuous stream of filter segments at spaced intervals in a relatively stiff plug wrap paper. By cutting the filter stream in a region where no filter element is present, a recess filter can be obtained - the stiff plugwrap paper providing sufficient rigidity to enable the final cigarette to be manufactured and used without crushing the exposed paper end of the filter.

Recess filters can incorporate one, two or more filter segments. It is often desired to incorporate activated carbon or other particulate additive within the filter. This is typically achieved through using a standard cellulose acetate (or similar) segment at the mouth end in order to present a plain white recessed end to the smoker, whilst a further segment closer to the tobacco column can comprise carbon (or other) granules interspersed within a fibrous matrix. In an alternative construction, a recess filter can include granular additive in a cavity positioned between two fibrous segments (one facing the mouth end and one facing the tobacco end of the filter tip). In a further example, a recess filter may include a single segment which has particulate additive embedded within the segment; such

'Monogranular Recess' filters are disclosed in WO 201 1/1 17584.

In the manufacture of cigarette filters an internal anchorage or anchoring adhesive is invariably applied to the inside of the wrapper (plugwrap). The purpose of this adhesive is to prevent the plug of filter material from coming out of the surrounding wrap during subsequent handling or use. It is known to apply this anchoring adhesive in the form of a number (e.g. 2-4) of continuous lines to the inside of the plugwrap immediately before the it enters the wrapping garniture in a cigarette filter making machine, whereupon it comes into contact with the filter material and forms a cohesive bond with it. It is also known to apply this internal anchorage adhesive in the form of a continuous spray rather than by direct application. The anchorage adhesive may be, for example, be a hot melt adhesive or an emulsion-based (e.g. EVA, PVA or PVOH) adhesive.

A characteristic of filter rods that contain activated carbon or other granular additives is that the granular material should only be located in specific areas that are separated from each other by areas of white fibrous filter material in which no granules should be present. The reason for this is that when these filters are eventually cut during cigarette manufacture, the cut is made through a white area so that only a clean white filter end is visible to smoker in the final cigarette. It is possible for stray carbon particles from the manufacturing process to become inadvertently entrained in the (white) filter material and/or in the surrounding wrapper material. If these particles become visible in the vicinity where the filter is finally cut, this gives rise to an unsightly filter end appearance. Such defects are termed 'Carbon Carry Over' (CCO) and, if the level of CCO is too high, the filters or filter cigarettes will be rejected.

According to the present invention in a first aspect there is provided a tobacco smoke filter (or filter element) comprising: a (e.g. outer) wrapper engaged around a longitudinally extending (e.g. cylindrical) core of tobacco smoke filtering material, wherein a first end of the (e.g. outer) wrapper is substantially flush with a first end of the core around which it is engaged, and a second end of the (e.g. outer) wrapper extends beyond a second end of the core around which is engaged to define a (e.g. tubular) cavity at the second end of the filter (or filter element); and an adhesive (e.g. anchoring adhesive) disposed (exclusively) between the (e.g. outer) wrapper and the core, wherein the adhesive (e.g. anchoring adhesive) is not disposed on the portion of the wrapper which extends beyond the second end of the core around which it is engaged to define the (e.g. tubular) cavity.

The radially inner face of the (e.g. outer) wrapper which extends beyond the second end of the core around which is engaged defines (e.g. with the second end of the longitudinally extending core) a cavity or recess, e.g. a tubular cavity/recess, at the second end of the recess filter (or filter element). Adhesive (e.g. anchoring adhesive) is not present on the radially inner face of the (e.g. outer) wrapper which extends beyond the second end of the core around which is engaged; the cavity/recess at the second end of the filter (or filter element) is free of adhesive (e.g. free of anchoring adhesive).

Thus according to an aspect of the invention there is provided a tobacco smoke filter (or filter element) comprising: a (e.g. outer) wrapper engaged around a longitudinally extending (e.g. cylindrical) core of tobacco smoke filtering material, wherein a first end of the (e.g. outer) wrapper is substantially flush with a first end of the core around which it is engaged, and a second end of the (e.g. outer) wrapper extends beyond a second end of the core around which is engaged such that the radially inner face of the (e.g. outer) wrapper which extends beyond the second end of the core around which is engaged defines (e.g. with the second end of the longitudinally extending core) a (e.g. tubular) cavity or recess at the second end of the filter (or filter element); and an adhesive (e.g. anchoring adhesive) disposed (exclusively) between the (e.g. outer) wrapper and the core;

characterised in that the adhesive (e.g. anchoring adhesive) is not disposed on the radially inner face of the (e.g. outer) wrapper which extends beyond the second end of the core around which is engaged. The applicants have found (see Example 2) that CCO is markedly decreased in the production of recess filters where no adhesive (e.g. no anchoring adhesive) is present on the radially inner face of the recess (i.e. where no adhesive is disposed/present on the radially inner face of the (e.g. outer) wrapper which extends beyond the second end of the core around which is engaged). Further, the applicants have found that there are other advantages associated with production of recess filters where no adhesive (e.g. no anchoring adhesive) is present on the radially inner face of the recess. For example, there is reduced knife contamination during manufacture because the filter rod is cut into recess filters in regions where there is no adhesive (e.g. no anchoring adhesive) and the knife does not therefore become contaminated with adhesive (or carbon).

The present applicants have thus found that by modifying the way in which internal anchorage/anchoring adhesive is applied during the manufacture of particulate-bearing recess filters, a dramatic reduction in the level of CCO associated with these products may be achieved. The anchoring adhesive is applied, preferably by spray, in localised areas corresponding to the position of the filter segment(s); no internal anchoring adhesive is applied to the (recess) areas where no segments are present. It will, of course, be appreciated that a lap seal (to secure the wrapper in cylindrical form surrounding the filter material) will continue to be required along the entire length of the filter, including the recess area; however, as is well known, the lap seal joins the inside of one longitudinal edge of the wrapper to the radially outer face of the wrapper to secure the wrapper in cylindrical form surrounding the filter material, and the lap seal is not therefore an adhesive (anchoring adhesive) disposed between the (e.g. outer) wrapper and the core.

It will be appreciated that the (anchorage) adhesive may be applied (e.g. by spray) to the filter segments rather than to the wrapper, or the adhesive may be applied to both the wrapper and the segments. Application to the wrapper only is the preferred method.

Preferably, the filter (or filter element) further comprises an additive. The additive is preferably distanced from the second end of the (e.g. outer) wrapper and/or core - e.g. such that it is not visible from the second end of the wrapper and/or core. The additive may be a particulate additive. The particulate additive may 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 particulate 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.

Preferably the adhesive (e.g. anchoring adhesive) is a hot melt adhesive or an emulsion-based (e.g. EVA, PVA or PVOH) adhesive. The (anchoring) adhesive may be disposed in localised area (e.g. as discrete patches or portions) positioned between the wrapper and the core. It is not essential that the patch or patches of internal anchoring adhesive are exactly the same length, size or dimensions as the filters/elements they are used to adhere, although clearly there should be a reasonable correlation. The width of the localised area (e.g. patch) is determined by the characteristics of the adhesive and the substrate, the strength of bond required and economic considerations. The localised area (e.g. patch) may extend across the entire width of the wrapper. However, it is preferred that the localised area (e.g. patch) extends over 20 to 40 % (e.g. one-third) of the width of the wrapper. It is preferred that the length of the localised area is the same as that of the longitudinally extending core of tobacco smoke filtering material. The length of the localised area may be shorter than that of the longitudinally extending core of tobacco smoke filtering material, for example such that the localised area of (anchoring) adhesive between the wrapper and the core is at least 1 mm from the second end of the core.

The tobacco smoke filter may be of length 12 to 40 mm, e.g. 17 to 35 mm, e.g. 20 to 30 mm. The recess section of the filter (that is, the length by which the second end of the outer wrapper extends beyond the second end of the core around which is engaged to define the cavity at the second (e.g. mouth) end of the filter) may have a length 3 to 10 mm, and is most preferably of length 4 to 6 mm. The longitudinally extending core of tobacco smoke filtering material may be of length 10 to 30 mm, e.g. 14 to 27 mm, e.g. 17 to 25 mm. The tobacco smoke filter (or filter element) may be of circumference 14 to 28 mm, for example 16 to 26 mm, for example 16 to 17 mm or 24 to 25 mm. The final filter cigarette may be ventilated or non-ventilated and of any circumference range traditionally used in smoking products (e.g. c. 14 to c. 28 mm circumference).

The wrapper (e.g. outer wrapper) may be paper, e.g. plugwrap paper, e.g. stiff plugwrap paper. The wrapper may be porous or non porous. The wrapper may be a paper of basis weight from about 40 to about 120 g/m². The wrapper may be of basis weight from about 80 to about 120 g/m², for example a basis weight of around 100 g/m², e.g. for a recess filter of standard (c. 24-25 mm) circumference. For slim or superslim recess filters (e.g. down to around 16-17 mm circumference), the wrapper may be a plugwrap paper of a lower basis weight, e.g. around 50 g/m². Preferably the wrapper is not transparent or substantially transparent.

The longitudinally extending core of tobacco smoke filtering material may comprise one or more (typically, 1 , 2 or 3) filter segments. If the longitudinally extending core comprises one segment and includes particulate additive, then the longitudinally extending core may be, for example, of any 'Monocarbon Recess' design discussed in WO

201 1/1 17584. If two or more segments are present, then carbon (or other particulate additive) may be entrained within a fibrous segment and/or present as a discrete granular layer.

The longitudinally extending core of tobacco smoke filtering material may comprise a rod shaped core of tobacco smoke filtering material having fully enclosed (e.g.

embedded) therewithin a (or at least one) pocket of additive (e.g. particulate additive). The rod shaped core of tobacco smoke filtering material may optionally have an additional wrapper (e.g. porous or non porous) engaged around the rod shaped core. The provision of the fully enclosed pocket of additive within the core of the tobacco smoke filtering material has the effect that the additive is distanced from the second end of the core (because there is tobacco smoke filtering material between the pocket of additive and the end of the core). This type of filter may be referred to as a "Smooth Core" filter.

The longitudinally extending core of tobacco smoke filtering material may have fully enclosed (e.g. embedded) therewithin a single pocket of additive (e.g. particulate additive) close to the first end (e.g. the tobacco end in a filter cigarette) and remote from the second end (e.g. the buccal or mouth end). The longitudinally extending core of tobacco smoke filtering material may have fully enclosed (e.g. embedded) therewithin a single pocket of additive (e.g. particulate additive) positioned equidistantly between the first end of the core (e.g. the tobacco end in a filter cigarette) and the second end of the core (e.g. the end of the core closest to the buccal or mouth end in a filter cigarette). The single longitudinally extending core of tobacco smoke filtering material may have fully enclosed therewithin one or more (e.g. two, three, four) separate pockets of additive (e.g. particulate additive). The fully enclosed (e.g. embedded) pockets of 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 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 longitudinally extending core of tobacco smoke filtering material comprising a rod shaped core of tobacco smoke filtering material having fully enclosed (e.g. embedded) therewithin a (or at least one) pocket of additive (e.g. particulate additive) may be manufactured, for example, by the methods and apparatus disclosed in WO 2006/059134.

In another example, the longitudinally extending core of tobacco smoke filtering material may comprise a rod shaped core of tobacco smoke filtering material and an additive (e.g. particulate additive) bearing wrapper engaged around the rod shaped core, the additive bearing wrapper having additive (e.g. particulate additive) adhered to one or more portion(s) of the radially inner face thereof with said additive bearing wrapper being free of additive around its circumference at the second end of the core. The absence of additive at the second end of the additive bearing wrapper has the effect that the additive is distanced from the second end of the core (because there no additive on the wrapper at the second end of the core). Preferably the additive bearing wrapper is free of additive around its circumference at both first and second ends of the core. The longitudinally extending core of tobacco smoke filtering material comprising a rod shaped core of tobacco smoke filtering material and an additive (e.g. particulate additive) bearing wrapper engaged around the rod shaped core, may be a filter element as disclosed in GB 2261152. This type of filter may be referred to as an "Active Patch" filter. The additive bearing wrapper may be porous or non porous.

As described above, the additive (if present) may be a particulate additive. The particulate additive may 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 particulate 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. If the longitudinally extending core of tobacco smoke filtering includes fully enclosed (e.g. embedded) pocket(s) of additive embedded therein, the additive may be a particulate additive such as activated carbon (see above), which is (for example) enclosed within the filtering material as a discrete pocket or pod of particles of particulate additive which is substantially separate from, and fully enclosed within, the filtering material. In another example, the fully enclosed (e.g. embedded) pocket(s) of 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 art.

In another example, the longitudinally extending core of tobacco smoke filtering material may comprise a downstream (e.g. recess end) longitudinally extending cylindrical plug of tobacco smoke filtering material and further longitudinally extending cylindrical plug of tobacco smoke filtering material upstream of the downstream plug, wherein the further cylindrical plug includes an additive (e.g. particulate additive, e.g. activated carbon) located (e.g. dispersed) within the tobacco smoke filtering material. The further plug may be of the type referred to as an "Active Acetate" plug. The downstream (e.g. recess end) longitudinally extending cylindrical plug of tobacco smoke filtering material may include flavouring agent (e.g menthol). If the downstream (e.g. recess end) longitudinally extending cylindrical plug of tobacco smoke filtering material includes flavouring agent, it may be any type of flavour bearing plug (flavour thread etc.). The longitudinally extending core of tobacco smoke filtering material may comprise one or more additional longitudinally extending cylindrical plugs of tobacco smoke filtering material (e.g. upstream of the further longitudinally extending cylindrical plug). The (or each) additional longitudinally extending cylindrical plugs of tobacco smoke filtering material may optionally include additive. The additive in the additional plug(s), if present, may be the same or different to that in the further plug.

In another example, the longitudinally extending core of tobacco smoke filtering material may comprise: a downstream (e.g. recess end) longitudinally extending cylindrical plug of tobacco smoke filtering material; and a further longitudinally extending cylindrical plug of tobacco smoke filtering material, wherein the further cylindrical plug is spaced longitudinally upstream from the downstream cylindrical plug; and a holding wrapper engaged around and joining the spaced plugs to define a cavity therebetween, wherein the cavity has an additive (e.g. particulate additive, e.g. activated carbon) located therein. The holding wrapper is generally an inner wrapper of plugwrap paper (and will be additional to the outer wrapper of the filter). However, the outer wrapper may serve as both outer wrapper and holding wrapper.

It will also be appreciated that this invention may also be applied to recess filters in which no particulate additive is present, for example flavour bearing, flavour thread, or shaped plastic mouthpiece filters etc.. Although there will no advantageous effect on CCO, there will be economical benefits as less adhesive will be required in the final product (as the internal anchoring adhesive will no longer be present in the recess area).

The tobacco smoke filtering material 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 (e.g. synthetic) non-wovens, and extruded material (e.g. starch, synthetic foams, extruded foams). The filtering material may be cellulose acetate.

According to the present invention in a further aspect there is provided a method of producing a recess tobacco smoke filter or filter element [e.g. a recess tobacco smoke filter or filter element comprising a wrapper engaged around a longitudinally extending core of tobacco smoke filtering material, wherein a first end of the wrapper is substantially flush with a first end of the core around which it is engaged, and a second end of the wrapper extends beyond a second end of the core around which is engaged to define a cavity at the second end of the filter (or filter element) and wherein an anchoring adhesive is disposed between the wrapper and the core, wherein the adhesive is not disposed on the portion of the wrapper which extends beyond the second end of the core around which it is engaged to define the cavity];

the method comprising the steps of:

advancing longitudinally a continuous flow of (e.g. individual e.g. pre-formed) filter elements and/or (e.g. pre-formed) multiple (e.g. dual) filter rods wherein the filter elements and/or multiple filter rods in the longitudinally advancing flow are longitudinally spaced from each other and each filter element and/or multiple filter rod comprises a longitudinally extending core of tobacco smoke filtering material;

applying an anchoring adhesive to a continuously advancing wrapper of stiff plugwrap paper (e.g. of basis weight 40 to 120 g/m²) in localised areas (e.g. patches) which correspond to the positions of the filter elements and/or multiple filter rods in the continuous flow, such that the anchoring adhesive is not applied to the wrapper in regions which correspond to the spaces between filter elements and/or multiple filter rods; and

engaging the adhesive bearing continuously advancing wrapper around the longitudinally advancing flow of filter elements and/or multiple (e.g. dual) filter rod to thereby form a continuous wrapped rod comprising: filter elements and/or multiple filter rods which are longitudinally spaced from each other and which each comprise a longitudinally extending core of tobacco smoke filtering material; and a common wrapper, wherein the anchoring adhesive is disposed exclusively between the common wrapper and the longitudinally extending cores.

Preferably the method comprises a further step of cutting the continuous wrapped rod (comprising longitudinally filter elements and/or multiple filter rods).

Optionally the (e.g. individual e.g. pre-formed) filter elements and/or (e.g. preformed) multiple (e.g. dual) filter rods may bear anchoring adhesive.

The method of producing a recess tobacco smoke filter or filter element [e.g. a recess tobacco smoke filter or filter element comprising a wrapper engaged around a longitudinally extending core of tobacco smoke filtering material, wherein a first end of the wrapper is substantially flush with a first end of the core around which it is engaged, and a second end of the wrapper extends beyond a second end of the core around which is engaged to define a cavity at the second end of the filter (or filter element) and wherein an anchoring adhesive is disposed between the wrapper and the core, wherein the adhesive is not disposed on the portion of the wrapper which extends beyond the second end of the core around which it is engaged to define the cavity] may comprise the steps of:

advancing longitudinally a continuous flow of dual filter rods wherein the dual filter rods in the longitudinally advancing flow are longitudinally spaced from each other and each dual filter rod comprises a longitudinally extending core of tobacco smoke filtering material;

applying an anchoring adhesive to a continuously advancing wrapper of stiff plugwrap paper (e.g. of basis weight 40 to 120 g/m²) in localised areas (e.g. patches) which correspond to the positions of the dual filter rods in the continuous flow, such that the anchoring adhesive is not applied to the wrapper in regions which correspond to the spaces between dual filter rods; and

engaging the adhesive bearing continuously advancing wrapper around the longitudinally advancing flow of dual filter rods to thereby form a continuous wrapped rod comprising: dual filter rods which are longitudinally spaced from each other and which each comprise a longitudinally extending core of tobacco smoke filtering material; and a common wrapper, wherein the anchoring adhesive is disposed exclusively between the common wrapper and the longitudinally extending cores (dual filter rods).

The (e.g. individual e.g. pre-formed) filter elements and/or (e.g. pre-formed) multiple filter rods in the flow are preferably aligned such that the longitudinally axes of their cylindrical cores are oriented along the longitudinal direction of the flow.

The (e.g. individual e.g. pre-formed) filter elements and/or (e.g. pre-formed) multiple filter rods in the longitudinally advancing flow are longitudinally spaced from each other (i.e. each filter element/rod is longitudinally spaced from the next along the continuous flow).

Preferably the method includes a further step of cutting the continuous wrapped rod in register with a position which is half way along each dual filter rod to provide dual product rods which each comprise two longitudinally extending cores of tobacco smoke filtering material which are longitudinally spaced from each other, and a common wrapper engaged around the longitudinally extending cores, wherein the anchoring adhesive is disposed exclusively between the common wrapper and the longitudinally extending cores.

According to the present invention in a further aspect there is provided a method of making filter smoking articles (e.g. cigarettes) comprising the steps of:

joining a wrapped tobacco rod to each end of a dual product rod comprising two longitudinally extending cores of tobacco smoke filtering material which are longitudinally spaced from each other, and a common wrapper engaged around the longitudinally extending cores, wherein an anchoring adhesive is disposed exclusively between the common wrapper and the longitudinally extending cores; and cutting the dual product rod in register with a position half way between the longitudinally extending cores of tobacco smoke filtering material.

Preferably the adhesive (e.g. anchoring adhesive) is a hot melt adhesive or an emulsion-based (e.g. EVA, PVA or PVOH) adhesive. The width of the localised area (e.g. patch) is determined by the characteristics of the adhesive and the substrate, the strength of bond required and economic considerations. The localised area (e.g. patch) may extend across the entire width of the wrapper. However, it is preferred that the localised area (e.g. patch) extends over 20 to 40 % (e.g. one-third) of the width of the plugwrap. It is preferred that the length of the localised area is the same as that of the longitudinally extending core of tobacco smoke filtering material. The length of the localised area may be shorter than that of the longitudinally extending core of tobacco smoke filtering material, for example such that the localised area of (anchoring) adhesive between the wrapper and the core is at least 1 mm from the second end of the core.

Preferably the anchoring adhesive is applied as a spray, for example a pulse spray. The spray adhesive system functions best when it is used with adhesives of low-medium viscosity. Preferably the adhesive has viscosity from 200 to 1000 cPS, more preferably 400 to 600 cPs. The spray can be applied in any suitable pattern within the localised area - e.g. as a single discrete patch, or as a series of parallel lines or in a spiral pattern.

Although it is preferred to apply the adhesive by spray, it will be appreciated that it is also possible to apply the adhesive by any technique for which a suitable control system exists for the application of discrete areas of adhesive onto paper, for example by brushes, rollers, printing, applicator guns, etc. Further, it is not essential that the patch or patches of internal anchoring adhesive are exactly the same length, size or dimensions as the filters/elements they are used to adhere, although clearly there should be a reasonable correlation.

the method comprising the steps of:

advancing longitudinally a continuous flow of (e.g. individual e.g. pre-formed) filter elements and/or (e.g. pre-formed) multiple (e.g. dual) filter rods wherein the filter elements and/or multiple filter rods in the longitudinally advancing flow are longitudinally spaced from each other and each filter element and/or multiple filter rod comprises a longitudinally extending core of tobacco smoke filtering material with anchoring adhesive on its outer face;

engaging a continuously advancing wrapper of stiff plugwrap paper (e.g. of basis weight 40 to 120 g/m²) around the longitudinally advancing flow of filter elements and/or multiple (e.g. dual) filter rods to thereby form a continuous wrapped rod comprising: filter elements and/or multiple filter rods which are longitudinally spaced from each other and which each comprise a longitudinally extending core of tobacco smoke filtering material; and a common wrapper, wherein the anchoring adhesive is disposed exclusively between the common wrapper and the longitudinally extending cores.

Preferably the method comprises a further step of cutting the continuous wrapped rod (comprising longitudinally filter elements and/or multiple filter rods). Optionally the wrapper may bear anchoring adhesive in localised areas (e.g. patches) which correspond to the positions of the dual filter rods in the continuous flow.

The applicants have found, advantageously, that there is reduced knife

contamination associated with production of filters or filter elements by methods according to the invention, because the filter rod is cut into recess filters/elements in regions where there is no adhesive (e.g. no anchoring adhesive) and the knife does not therefore become contaminated with adhesive (or carbon).

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, more preferably, by a full tipping overwrap (which engages around the full filter length and the adjacent end of the tobacco rod). The cigarette may include a tipping overwrap (of e.g. a stiff tipping paper) in conjunction with the outer wrapper of the filter to give the desired (e.g. further increased) stiffness to the final recess filter cigarette.

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 location (pocket or patch or portion) of additive, depending upon the ventilation and filtering performances required. Ventilation upstream of and/or in register with a location (pocket or patch or portion) of additive is frequently preferred. There may be ventilation between locations (pockets or patches or portions) of additive when two or more locations are present.

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.

The present invention will now be illustrated with reference to the following

Examples and the attached drawings in which FIGURE 1 schematically illustrates a recess filter according to an embodiment of the invention; FIGURE 2 schematically illustrates a recess filter according to a different further embodiment of the invention; FIGURE 3 schematically illustrates a method of making recess filters according to the embodiment of Fig 2; and FIGURE 4 illustrates an overview of a control system for a typical pulse spray gluing system for making filters of the invention, by methods of the invention.

Examples

Figure 1 shows an 'Active Patch' recess filter comprising an outer wrapper 3 of plugwrap paper of basis weight 100 g/m² engaged around a (single) cylindrical longitudinal extending core of tobacco smoke filtering material 5 and held in place by a conventional lapped and stuck seam (not shown). The first end of the outer wrapper 3a is substantially flush with first end 5a of the core 5 around which it is engaged, and second end of the outer wrapper 3b extends beyond second end 5b of the core 5 around which is engaged to define a cavity 6, a recess at the second (mouth) end of the filter. An anchoring adhesive (e.g. EVA) is disposed on the radially inner face of the wrapper exclusively between the outer wrapper and the core, to hold the core in place within the wrapper. The anchoring adhesive is applied (see below) in such a way that adhesive is not disposed on the portion of the wrapper 3b which extends beyond the second end of the core around which it is engaged to define the (e.g. tubular) cavity; in other words anchoring adhesive is not present on portion of the wrapper 3b which extends beyond the second end of the core around which it is engaged to define the (e.g. tubular) cavity.

It will be appreciated that it is the radially inner face of the outer wrapper 3 which extends beyond the second end of core 5b, which defines, with the second end of the longitudinally extending core 5b, the tubular cavity (recess) 6, located at the second end of the filter. Anchoring adhesive is not present on the radially inner face of the outer wrapper 3 which extends beyond the second end of the core 5b around which is engaged; the cavity/recess at the second end of the filter (or filter element) is free of adhesive.

The single longitudinally extending core of tobacco smoke filtering material 5 is an

"Active Patch" filter element, such as are well known in the art, for example as disclosed in GB 2261152. The core 5 comprises a rod shaped core 7 of tobacco smoke filtering material in the form of cellulose acetate tow, and an additive (particulate additive) bearing wrapper 9 engaged around the rod shaped core, the additive bearing wrapper 9 having additive in the form of activated carbon granules adhered to a portion or patch 1 1 of the radially inner face thereof, with said additive bearing wrapper being free of additive around its circumference at the second end 9a of the core. The filter 1 is of 27mm length, of which the cavity 6, or recess, at the second end is of length 6mm. The patch 1 1 is centrally located between the two ends of core 7; the core 7 has both ends free of additive. The 'Active Patch' filter element may, for example, be made by the method disclosed in GB 2261 152.

Figure 2 shows an example of a 'Smooth Core' recess filter. Figure 2 shows a tobacco smoke filter 101 comprising an outer wrapper 103 of plugwrap paper of basis weight 100 g/m² engaged around a single cylindrical longitudinal extending core of tobacco smoke filtering material 105 and held in place by a conventional lapped and stuck seam (not shown). The single longitudinal extending core of tobacco smoke filtering material 105 is a 'Smooth Core' filter, for example as disclosed in WO 2006/059134. The core 105 comprises a rod shaped core 107 of tobacco smoke filtering material in the form of cellulose acetate tow, having fully enclosed (e.g. embedded) therewithin a pocket 199 of additive in the form of particles of activated carbon. The first end 103a of the outer wrapper 103 is substantially flush with a first end 105a of the core around which it is engaged, and a second end 103b of the outer wrapper extends beyond a second end 105b of the core around which is engaged to define a cavity 106, a recess at the second (mouth) end of the filter. An anchoring adhesive (e.g. EVA) is disposed on the radially inner face of the outer wrapper exclusively between the outer wrapper 103 and the core, to hold the core in place within the wrapper. The anchoring adhesive is applied (see below) in such a way that anchoring adhesive is not disposed on the portion of the wrapper 103b which extends beyond the second end of the core around which it is engaged to define the (e.g. tubular) cavity; in other words anchoring adhesive is not present on the portion of the wrapper 103b which extends beyond the second end of the core around which it is engaged to define the (e.g. tubular) cavity.

It will be appreciated that it is the radially inner face of the outer wrapper 103 which extends beyond the second end of core 105b, and defines, with the second end of the longitudinally extending core 105b, the tubular cavity (recess) 106, at the second, or mouth, end of the filter. Anchoring adhesive is not present on the radially inner face of the outer wrapper 103 which extends beyond the second end of the core 105b around which is engaged; the cavity/recess at the second end of the filter (or filter element) is free of anchoring adhesive.

The filter 101 is of 27mm length, of which the cavity 106, or recess, at the second end is of length 6mm. The pocket 199 is located towards the first or tobacco end of core 107, but it will be appreciated that core 107 has both ends free of additive (because it the additive is fully embedded within the core); the additive is invisible from the second or mouth end of the filter. The 'Smooth Core' filter element 107 may, for example, be made by the method disclosed in WO 2006/059134.

Methods for the inclusion of filter elements into recess filters are well known in the art. In known methods, a continuous stream of longitudinally extending filtering cores of tobacco smoke filtering material are arranged appropriately (in a spaced arrangement) using a filter making machine, and fed through a wrapping garniture where a stiff plugwrap is wrapped around the filtering cores, and fixed around the filtering cores with a

conventional lapped and stuck seam. In the known techniques, a number (e.g. 2-4) of continuous lines of anchoring adhesive are applied to the inside of the plugwrap

immediately before it enters the wrapping garniture of the cigarette filter making machine; the wrapper is then applied to the filtering cores by the garniture whereby the anchoring adhesive on the wrapper comes into contact with the filtering material and forms a cohesive bond between the wrapper and the filtering cores.

FIGURE 3 schematically illustrates a method of making recess filters of the invention according to the embodiment of Fig 2. Figure 3 shows a continuous flow of spaced filter rods 115 advancing longitudinally in the direction of arrow 116. Each filter rod 115 includes two longitudinally extending cores of tobacco smoke filtering material 105 (see Fig 2) placed end to end in mirror image relationship. It will be appreciated that filter rods 115 are made by the methods disclosed in WO 2006/059134, and that the line 117 between each pair of cores of tobacco smoke filtering material 105 represents the line along which the filter rods 115 will ultimately be cut to provide single cores 115.

The flow of filter rods 115 enters a wrapping garniture (not shown) where a continuously advancing outer wrapper of stiff plugwrap paper 118 of basis weight 100 g/m² plugwrap is wrapped and around the longitudinally advancing flow of filtering cores and fixed using a lapped and stuck seam (as is well known).

According to the invention, an EVA anchoring adhesive is applied to hold the filter rods in place on/in the plugwrap. The anchoring adhesive is applied by a pulse spray method, to the inner surface of the advancing plugwrap 1 18 exclusively in localised areas/patches 119 corresponding to those regions where filter rods 1 15 will be present, immediately before plugwrap 1 18 enters the wrapping garniture of the cigarette filter making machine. The advancing wrapper is then applied to the filtering cores by the garniture whereby the localised areas 119 of adhesive on the inner surface of the wrapper 118 come into contact with the filtering material of filter rods 1 15 to form a cohesive bond between the wrapper and the filtering cores. It will be appreciated that anchoring adhesive is not applied to the inner surface of the plugwrap 1 18 in areas (those areas other than localised areas 1 19) which will not come into contact with filter rods 15. In other words anchoring adhesive is not applied to the inner surface of the plugwrap 1 18 in areas which correspond to spaces in the spaced flow of filter rods; these spaces will form the recess in the final product recess filters/recess filter cigarette.

The wrapped filter rods 115 exit the garniture and are cut (along lines 1 17) into multiple filter rods. A rod including two filters is referred to herein as dual product rod (see Figure 3a). As is well known in the art, in the subsequent cigarette manufacturing procedure, the dual product rod 120 is joined at each end to a wrapped tobacco rod, and then cut along the line shown by arrow 121 to provide two recess filter cigarettes. It will be appreciated that line 121 represents a line half way along the spacing between adjacent filter rods 1 15 and thus the cut is located in the region where no filter (and no anchoring adhesive) is present; the cut therefore forms the recess at the end of each cigarette, and the final product filter cigarette has no anchoring adhesive present on the radially inner face of the outer wrapper 1 18 in this recess region.

Figure 4 shows an overview of the control system for the pulse spray gluing system of Figure 3. As shown in Figure 4, pulse spray adhesive applicator 201 applies the localised areas 1 19 of adhesive to the inner surface of the wrapper 1 18 immediately prior to entry of wrapper 1 18 into the garniture (not shown).

Adhesive is supplied from pressurized glue tank 202 to pulse spray adhesive applicator 201. A pressure controller 203 controls the pulse spray air pressure in the applicator 201 and in the pressurized glue tank, to ensure an appropriate amount of glue is applied in localized area 1 19. A spray controller 204 (a microprocessor, a PC or similar) is used to control the number and size of localised areas, and to control the pressure controller 203 and pulse spray adhesive applicator 201. It will be appreciated that the (anchorage) adhesive may be applied (e.g. by spray) to the filter segments rather than to the wrapper, or the adhesive may be applied to both the wrapper and the segments. However, application to the wrapper only is the preferred method.

Example 2 - reduction in CCO

Recess filters were manufactured using standard filter making machinery as is well known in the art. These were cut into filter rods of 108mm length, each comprising 4x27mm length tips. Each tip had a 5mm recess, a 10mm downstream longitudinally extending plug of non-wrapped cellulose acetate filtering material facing the mouth end, and a further (upstream) longitudinally extending 12mm plug of cellulose acetate filtering material containing 30/70 mesh coconut-based activated carbon interspersed within the fibrous matrix at the end facing the tobacco column.

At regular production intervals, a random sample of 160 filter rods were taken from the machine and each of these were cut at the positions corresponding to the mouth end, thereby giving a total of 640 filter tips for evaluation. Trained operators then visually assessed each of these 640 filter tips and recorded the number of tips in which any dark particle (assumed to be carbon) was visible to the naked eye. This is known as the CCO number and is expressed as a percentage.

The original set up of the machine was with a conventional system for applying internal anchorage adhesive as a continuous spray to the inner surface of the heavyweight (100gsm) plugwrap used to combine the segments and provide the rigidity for the recess mouth end. The measured CCO results for 10 prior art samples (i.e. 10 lots of 640 tips) were as follows:

• Mean CCO: 7.81 %

• Range of mean CCO for each sample: 2.5% - 15.625% The filter making machine was then modified in accordance with the invention, i.e. the internal anchorage adhesive was applied by a control mechanism such that localised patches of adhesive (corresponding to the position of where the fibrous plugs would be located) were sprayed onto the internal surface of the plugwrap. For example, in this case, adhesive would be present over the 22mm length of the two segments in each tip, but absent from the 5mm length corresponding to the exposed recess end. The measured CCO results for 10 samples of the invention (i.e. 10 lots of 640 tips) made in accordance with the method of invention were:

• Mean CCO: 0.38%

· Range of mean CCO for each sample: 0.13% - 0.75%

It can be seen that a substantial reduction of around 95% in CCO was achieved by the invention.

Claims

1. A tobacco smoke filter or filter element comprising:

a wrapper engaged around a longitudinally extending core of tobacco smoke filtering material, wherein a first end of the wrapper is substantially flush with a first end of the core around which it is engaged, and a second end of the wrapper extends beyond a second end of the core around which is engaged to define a cavity at the second end of the filter or filter element;

and an adhesive disposed between the wrapper and the core, wherein the adhesive is not disposed on the portion of the wrapper which extends beyond the second end of the core around which it is engaged to define the cavity.

2. A tobacco smoke filter or filter element comprising:

a wrapper engaged around a longitudinally extending core of tobacco smoke filtering material, wherein a first end of the wrapper is substantially flush with a first end of the core around which it is engaged, and a second end of the wrapper extends beyond a second end of the core around which is engaged such that the radially inner face of the wrapper which extends beyond the second end of the core around which is engaged defines a cavity or recess at the second end of the filter or filter element; and

an adhesive disposed between the wrapper and the core; characterised in that the adhesive is not disposed on the radially inner face of the wrapper which extends beyond the second end of the core around which is engaged.

3. A filter or filter element according to claim 1 or 2 further comprising an additive distanced from the second end of the core.

4. A filter or filter element according to claim 3 wherein the additive is a particulate additive.

5. A filter or filter element according to any preceding claim wherein the longitudinally extending core of tobacco smoke filtering material comprises a rod shaped core of tobacco smoke filtering material having fully enclosed therewithin a (or at least one) pocket of additive.

6. A filter or filter element according to any of claims 1 to 4 wherein the longitudinally extending core of tobacco smoke filtering material comprises a rod shaped core of tobacco smoke filtering material and an additive bearing wrapper engaged around the rod shaped core, the additive bearing wrapper having additive adhered to one or more portion(s) of the radially inner face thereof with said additive bearing wrapper being free of additive around its circumference at the second end of the core.

7. A filter or filter element according to any of claims 1 to 4 wherein the longitudinally extending core of tobacco smoke filtering material comprises a downstream longitudinally extending cylindrical plug of tobacco smoke filtering material and a further longitudinally extending cylindrical plug of tobacco smoke filtering material upstream of the downstream plug, wherein the further cylindrical plug includes an additive located within the tobacco smoke filtering material.

8. A filter or filter element according to any of claims 1 to 4 wherein the longitudinally extending core of tobacco smoke filtering material comprises a downstream longitudinally extending cylindrical plug of tobacco smoke filtering material; and a further longitudinally extending cylindrical plug of tobacco smoke filtering material spaced longitudinally upstream from the downstream cylindrical plug; and a holding wrapper engaged around and joining the spaced plugs to define a cavity therebetween, wherein the cavity has an additive located therein.

9. A filter or filter element according to any preceding claim wherein the filtering material comprises one or more of natural or synthetic filamentary tow, e.g. of cotton or plastics such as polyethylene or polypropylene, cellulose acetate filamentary tow, natural or synthetic staple fibres, cotton wool, web material such as paper, non-woven material, extruded material (e.g. starch, synthetic foams, extruded foams), or cellulose acetate.

10. A filter or filter element according to any preceding claim wherein the adhesive is a hot melt adhesive or an emulsion-based adhesive.

11. A filter or filter element substantially as hereinbefore described with reference to Figure 1 or Figure 2.

12. A method of producing a recess tobacco smoke filter or filter element comprising the steps of:

advancing longitudinally a continuous flow of filter elements and/or multiple filter rods wherein the filter elements and/or multiple filter rods in the longitudinally advancing flow are longitudinally spaced from each other and each filter element and/or multiple filter rod comprises a longitudinally extending core of tobacco smoke filtering material;

applying an anchoring adhesive to a continuously advancing wrapper of stiff plugwrap paper in localised areas which correspond to the positions of the filter elements and/or multiple filter rods in the continuous flow, such that the anchoring adhesive is not applied to the wrapper in regions which correspond to the spaces between filter elements and/or multiple filter rods; and

engaging the adhesive-bearing continuously advancing wrapper around the longitudinally advancing flow of filter elements and/or multiple (e.g. dual) filter rods to thereby form a continuous wrapped rod comprising filter elements and/or multiple filter rods which are longitudinally spaced from each other within a common wrapper, wherein the anchoring adhesive is located exclusively between the common wrapper and the filter elements and/or multiple filter rods.

13. A method according to claim 12 comprising a further step of cutting the continuous wrapped rod.

14. A method of producing a recess tobacco smoke filter or filter element comprising the steps of:

applying an anchoring adhesive to a continuously advancing wrapper of stiff plugwrap paper in localised areas which correspond to the positions of the dual filter rods in the continuous flow, such that the anchoring adhesive is not applied to the wrapper in regions which correspond to the spaces between dual filter rods; and

engaging the adhesive bearing continuously advancing wrapper around the longitudinally advancing flow of dual filter rods to thereby form a continuous wrapped rod comprising: dual filter rods which are longitudinally spaced from each other within a common wrapper, wherein the anchoring adhesive is disposed exclusively between the common wrapper and the dual filter rods.

15. A method according to claim 14 comprising a further step of cutting the continuous wrapped rod in register with a position which is half way along each dual filter rod to provide dual product rods which each comprise two longitudinally extending cores of tobacco smoke filtering material which are longitudinally spaced from each other, and a common wrapper engaged around the longitudinally extending cores, wherein the anchoring adhesive is disposed exclusively between the common wrapper and the longitudinally extending cores.

16. A method of making filter smoking articles (e.g. cigarettes) comprising the steps of: joining a wrapped tobacco rod to each end of a dual product rod comprising two

longitudinally extending cores of tobacco smoke filtering material which are longitudinally spaced from each other, and a common wrapper engaged around the longitudinally extending cores, wherein an anchoring adhesive is disposed exclusively between the common wrapper and the longitudinally extending cores; and cutting the dual product rod in register with a position half way between the longitudinally extending cores of tobacco smoke filtering material.

17. A method according to any of claims 12 to 16 in which the adhesive is applied as a spray.

18. A method according to any of claims 12 to 17 wherein the adhesive has viscosity from 200 to 1000b cPS, more preferably 400 to 600 cPs.

19. A method substantially as hereinbefore described with reference to Figure 3 and/or Figure 4.

20. A filter cigarette comprising a filter according to any of claims 1 to 11 or a filter made by a method according to any of claims 12 to 18 joined to a wrapped tobacco rod with the first end of the filter towards the tobacco.

21. A multiple rod comprising a plurality of filters according to any of claims 1 to 11 or a plurality of filters made by a method according to any of claims 12 to 18 integrally joined end-to-end in a mirror image relationship.