CA1194753A - Smoke filter - Google Patents
Smoke filterInfo
- Publication number
- CA1194753A CA1194753A CA000406561A CA406561A CA1194753A CA 1194753 A CA1194753 A CA 1194753A CA 000406561 A CA000406561 A CA 000406561A CA 406561 A CA406561 A CA 406561A CA 1194753 A CA1194753 A CA 1194753A
- Authority
- CA
- Canada
- Prior art keywords
- filter
- wrapper
- core
- impermeable
- external
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- A—HUMAN NECESSITIES
- A24—TOBACCO; CIGARS; CIGARETTES; SIMULATED SMOKING DEVICES; SMOKERS' REQUISITES
- A24D—CIGARS; CIGARETTES; TOBACCO SMOKE FILTERS; MOUTHPIECES FOR CIGARS OR CIGARETTES; MANUFACTURE OF TOBACCO SMOKE FILTERS OR MOUTHPIECES
- A24D3/00—Tobacco smoke filters, e.g. filter-tips, filtering inserts; Filters specially adapted for simulated smoking devices; Mouthpieces for cigars or cigarettes
- A24D3/04—Tobacco smoke filters characterised by their shape or structure
- A24D3/043—Tobacco smoke filters characterised by their shape or structure with ventilation means, e.g. air dilution
Landscapes
- Cigarettes, Filters, And Manufacturing Of Filters (AREA)
- Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
SMOKE FILTER
This invention provides a smoke filter element comprising a filtering core, a smoke impermeable wrapper in surrounding engagement with the core, at least one internal passage defined between the impermeable wrapper and core and open at an end of the element, and at least one external passage defined by the outer surface of the impermeable wrapper and extending to an end of the element; and a cigarette filter comprising such an element having engaged around said impermeable wrapper tipping material which provides, when the filter is drawn on in use, for the ingress of external air laterally therethrough into said external passage(s). The tipping material may be a tipping overwrap incorporating the filter in a filtered cigarette. The impermeable wrapper may have longitudinal corrugations providing the passages, which may extend fully or only partially the length of the wrapper. The impermeable wrapper can have a circumferential groove communicating with the external passage(s), there being air dilution through the tipping material directly into the groove.
SMOKE FILTER
This invention provides a smoke filter element comprising a filtering core, a smoke impermeable wrapper in surrounding engagement with the core, at least one internal passage defined between the impermeable wrapper and core and open at an end of the element, and at least one external passage defined by the outer surface of the impermeable wrapper and extending to an end of the element; and a cigarette filter comprising such an element having engaged around said impermeable wrapper tipping material which provides, when the filter is drawn on in use, for the ingress of external air laterally therethrough into said external passage(s). The tipping material may be a tipping overwrap incorporating the filter in a filtered cigarette. The impermeable wrapper may have longitudinal corrugations providing the passages, which may extend fully or only partially the length of the wrapper. The impermeable wrapper can have a circumferential groove communicating with the external passage(s), there being air dilution through the tipping material directly into the groove.
Description
7~
~ rhis invention relates to smoke filtration, especially tobacco smoke filtration. It provides filters and elements which are widely applicable for smoke and other filtering uses, but which are discussed and illustrated herein mainly in terms of cigarette filters, this being the application of currently greatest commercial interest. The invention provides a smoke filter element comprising a filtering core, a smoke impermeable wrapper in surrounding engagementwith the core, at least one (internal) passage defined between the impermeable wrapper and core and open at an end of the element, and at least one further (external) passage defined by the outer surface of the impermeable wrapper and extending to an end of the element. Suitably the impermeable wrapper is profiled to provide the internal and external passages, e.g. it may be longitu~;n~lly grooved or corrugated to provide the said passages;
accordingly the invention also provides a smoke filter element comprising a filtering core, and a corrugated smoke impermeable wrapper dPf;n;ng first tinternal) passages between the wrapper and core which extend longitudinally to an end of the element and further (external) passages externall~ of the wrapper which extend ~ongitu~;n~lly to an end of the element.
Elements according to the invention are intended primarily for use as filters with tipping material which provides, when the filter is drawn on in use, for the ingress of external air laterally theretHrough into the further (external) passages. Such ventilating tipping material may be applied around the impermeable wrap er as a step in the filter manufacturing procedure, or it may be the tipping ',~,,; ~
.
'o'~
overwrap whlch is applied to join element to tobacco rod in the manufacture of filter cigarettes. Accordingly the invention further provides a cigarette filter comprising a filtering core, a smoke - impermeable wrapper in surrounding engagement with the core, tipping material in surrounding engagement with the impermeable wrapper, at least one (internal) passage defined between the impermeable wrapper and core and open at an end of the filter, and at least one further (external) passage defined between the impermaable wrapper and tipping material and open at an end of the filter, the tipping material providing, when the filter is drawn on in use, for the ingress of external air laterally therethrough into said further texternal) passage(s).
The passages may extend only partially the length of the element or filter but one, more, or all can instead extend from one element or filter end to the other; any given passage may be of substantially constant cross-section along its length, or could (especially if it extends from end to end of the filter or element) be constricted over a t~rm; n~l and/or intPrr~ te region. The passages may extend axially of the element or filter or follow a curved path.
Where the impermeable wrapper is formed with longitudinal grooves or corrugations to provide said passages, the grooves or corrugations may thus extend the full wrapper length (though possibly with the grooves or corrugations being smaller at an end or int~rr-~;ate region), or may terminate (e.g. at an ~ncorrugated or circumferentially grooved or corrugated region) to close one or more passages (at least in the complete filter) at a t~r~;n~1 or inter-mediate portion of the wrapper. Other profiled configurations of 5~
the impermeable wrapper are possible Eor defining the said passages (e.g. dimples).
In particularly preferred embodimen-ts of the present invention, the impermeable wrapper has a circumferential groove into which at least one said external passage opens, this groove usually simultaneously closing the internal passage(s). In ilter cigarettes according to the invention employing such elements, there can be ventilation through the tipping material directly into the circumferential groove and hence into the communicating external paSsage(s);~or example~ventilating perforations may be provided in the tipping material in a circumferential ring in register with the circumferential groove. Various configurations are possible; for example, the circumferential groove may be disposed mid-way along - the wrapper, with internal and external passages extending therefrom in opposite directions to both ends of the element; or the circum-ferential groove may be towards one end of the element where the impermeable wrapper is circumferentially corrugated or otherwise conformed to close the circumferential groove from that end, the internal and external passages extending from the circumferential groove to the other end of the element; in another variant, the circumferential groove is at one end G~ the wrapper, being open to that end with the internal and external passages extending therefrom to the other end; other embodiments have a plurality of the circum-ferential grooves spaced along the wrapper, e.g. at opposite ends thereof~ The impermeable wrapper to be employed in the production of this type of element according to the invention can simply be pre-profiled in the normal way to provide the required passages, with each region to constitute a circumferential groove bèing left plain ~L?~ f 5;~
and unprofiled; when the profiled wrapper is applied round the core, it is found that the said plain unprofiled regions naturally adopt the conformation of circumferential grooves. This is especial].y effective in the case of corrugation to provide the passages.
When an embossed or otherwise shaped impermeable wrapper provides the said passages, the core is suitably of substantially constant circular section and the tipping material likewise in the form of a substantially right circular cylinder.
When they do not extend the fu]l wrapper length, the internal and ex-ternal passages will usually be open at the same end of the element or filter, and will usually be closed at the same position along its length, e.g. at its other end, but neither of these features is essential; the former and latter passages can be closed at different longitudinal positions each of which may be at an end of the element or filter or between its ends.
The filtering core of the element or filter of the invention can be of any of the whole range of cigarette filter materials, e.g. of bonded or unbonded staple fibres or ~ilamentary tow (of cellulose acetate, or polyolefin etc), creped paper, or air-permeable foamed matexial. The core may be of uniform or non-uniform str~cture and composition along its length; it may be integral or of composite structure - e.g. incorporating a wrapper and/or having separate plugs of the same or differing characteristics ~e.g. pressure drop) and/or composition; the core may extend wholly or only partially the length of the element or filter, and where the core is a composite of two or more plugs adjacent plugs may abut or be spaced apart. The core may be unwrapped or include a plugwrap which is perforate and/or of inherently smoke-permeable material; the core could instead have an impermeable plugwrap or integral (e.g. heat-or solvent-fused) skin. ~he core may incorporate particulate additive uniforr~lly dispersed therethrough or localised in at least one region or inter-plug space; the core may have a profiled (e.g.
longitudinally grooved) periphery, and it may have one or more internal passages or cavities which may be~filled or unfilled. The core may include one or more components which do not have a filtering effect but which merely serve to increase the pressure drop; and there may be used as or in the filtering core of elements and filters according to the invention a high pressure drop, low retention plug oÇ gathered coarse fibres or of gathered embossed plastics, metal (e.g. aluminium) or other foil. In some embodiments the impermeable wrapper surrounds a cavity or recess open at an end of the filter elernent or filter, and in use such a recess or cavity may be disposed against the wrapped tobacco rod or exposed at the buccal end of the - filtered cigarette.
Whilst the filtering core of elements according to the invention may be a composite structure as mentioned above, e.g. made up of abutting or longi~u~;n~lly spaced plugs, the profiled imperm-eable wrapper which extends the full element length renders the element overall a coherent, unita^y structure.
The impermeable wrapper is suitably a paper/thermoplastics polymer larninate, e.g. a paper/thermoplastics/paper laminate, the plastics layer preferably being of polyolefin, e.g. polyethylene.
Such a laminate has good ernbossing characteristics and retains its impermeability and embossed configuration well. The impermeable wrapper is preferably secured around the core by way of a lapped and stuck seam; it may also or instead be secured to the core by one or rj ~3 more longitudinal adhesive lines.
The tipping material may be air-permeable, but when it is the tipping overwrap ~oining the element to a tobacco column it is more usually of substantially impermeable material having perforations in open communication with the said further passages. The element may have a wrap of air~permeable material, giving a filter of plain external appearance and around which the tipping overwrap (or ring tipping) is engaged in filter cigarette manufacture, but this is not usually necessary.
In use as part of a filtered cigarette, the filter according to the invention can provide (via the internal passage(s) between impermeable wrapper and core) for some by-pass of smoke around part of the core length, various controlled effects being thereby obtainable according to the filter structure adopted as illustrated in some of the speciric em~odiments described below; in these cases, of course, the core does not have a smoke-impermeable layer between itself and the ;mpP --hle wrapper. The external passage(-s), between impermeable wrapper and tipping material, may be open to the buccal end and such that ventilation air is drawn thereinto and passes directly into the smokers mouth with little or no previous mixing with smoke. An external passage may - instead open at the tobacco rod end and be such that ventilation air drawn thereinto passes upstream to the toabcco rod and then downstream through the filter core. Constriction of a passage may affect or determine the degree and direction of flow in its unconstricted portion(s). A filter according to the invention may ha~e at least one external passage open only at the buccal end and at least another such passage open only at the other end; likewise, at least one . .
'7S~
internal passa~e ~ay open only at the buccal end and at least one other open only a-t the other end.
Elements according to the invention are suitably made by first forming the core (as a continuous or discrete finite length rod), profiling (e.g. corrugating) the impermeable wrapper to the ,required conflguration, and wrapping and securing the profi]ed ~ hle wrapper around the core; tipping material may subsequentlY
be wrapped around the impermeable wrapper; this tipping material may ,be the tipping overwrap which is employed to join element and tobacco rod together during formation of filter cigarettes in conventional manner.
Normally the core will be formed as a con-tinuous rod which is then continuously wrapped in the pre-profiled impermeable wrapper, the resu3ting continuous composite then being cut transversely into finite lengths. A wrap of air-permeable material may if desired be applied continuously around the composite of core and profiled wrapper before the cutting into finite lengths. For filter cigarette manufacture, a double length such product is disposed with a wrapped tobacco rod abutting either end, ventilating tipping over-wrap is ap,plied to join the tobacco rods and intervening element orfilter rod together, and the resulting comDination is cut in half to produce two filter cigarettes. The initially produced continuous filter or element is normally cut into even multiple (e.g. sextuple) length units for supply to the filter cigarette manufacturer who then cuts these multiple lengths into double lengths for use in filter cigarette production as described above. It will be appreciated that, in the case of individual filter or element lengths according to the invention in which the internal and external passages extend from one end only to terminate short of the other end so that the two '5.~
filter o~ element ends are different, the initial even multiple length rods supplied by the filter manufacturer and from which the individual lengths are eventually formed can have identical ends -e.g. the even multiple length rod could have passages extending from both ends or closed at both ends, according to whether the passageS
in tha final filter cigarette are to be open to the tobacco or at the buccal end respectivel~. Such double and multiple length rods also form part of the present invention.
The impermeable wrapper preferably exerts substantially no radial compression on the core and preferably does not impress its profiled configuration into the core surface. The ;mpprm~hle wrapper is prferably pre-profiled with longitll~i n~l ly extending grooves or corrugations; these may be discontinuous, with longitud-inally grooved or corrugated lengths spaced apart by portions (e.g.
plain or transversely corrugated or grooved) which in the finished filter close off longitudinal passages provided by the wrapper.
Instead of corruga-tions, the impermeable wrapper could be embossed with dimples to provide in the finished product a network of random or ordered passages, the dimpled lengths of the wrapper again optionally being spaced apart by segments which are plain or configured so as to close off passages in the finished product.
Embodiments of the invention are described below, by way of example only, with reerence to the accompanying schematic drawings tnot to scale), in which like reference numerals denote like parts and in whlrh :- -Figure 1 is a longitudinal sectional view on line I-I of Fig.3 of a filter and element according to the invention incorporated in a filter cigarette according to the invention;
S~3 Figure 2 is a ~rag~PIltary sectiQnal view of the Fig.l element and filter taken on lines II-II of Fig.l;
Figure 3 is a sectional view of the Fig.l filter and element taken on lines III-III of Fig.l;
Figures ~ to 8 are longitudinal sectional views, similar to that of Fig.l, of five further different filters and elements accordiny to the invention incorporated in respective filter cigarettes accordlng to the invention;
Figure 9 is a similar longitudinal sectional view of yet another filter and element according to the invention;
Figure 10 is an end elevation! more to scale, of the Fig.9 element and filter;
Figure 11 is a longitudinal sectional view of another element, filter and filter cigarette according to the invention;
Figuresl2 and 13 are cross sectional views along lines XII-XII and XIII-XIII respectively of Fig.ll;
Figure 14 is a perspective view of the filter element according to the invention employed in the filter of Fig.l~l;
Figure 15 is a view similar to Fig.ll of another element, filter and filter cigarette according to the invention;
Figure 16 is a perspective view of the filter element according to the invention employed in Fig.15;
Figure 17 is a view, similar to that of Fig.16, of another filter element according to the invention; and ~ Figures 18 to 20 are schematic longitudinal ~ectional views of multiple length elements according to the invention.
5.3 The ~ilter element illustrated in Figures 1 to 3 consists oE a filter core made up of a plug 2 of filtering material wrapped in a smoke-permeable (inherently smoke-permeable andJor perforate)or smoke-impermeable~ plugwrap ~, and a smoke-impermeable wrapper 6 in surrounding engagement with the core; tipping material 8 in surrounding engagement with the impermeable wrapper completes the filter. The impermeable wrapper 6 has longitudinal corrugations 10 closed at one end 22 of the filter by circumferential corrugations 12, the longitudinal corrugations 10 providing passages 14 (Fig.3) 1~ between core and impermeable wrapper and passag~ 16 between impermeable wrapper and tipping material, all of these passages beinq open at the end 18 of the filter. Tipping material 8 is of smoke~impermeable material but has a circumferential ring of perforations 20 via which passages 1~ are in communication with the external air.
Tipping material 8 is a tipping overwrap which projects beyond the core and wrapper 6 to join the element to a wrapped tobacco column 23 at end 22; it could instead join the elemen~ to such a wrapped tobacco rod at the opposite end 18.
Imperme~le wrapp~r 6 is a paper/polyethylcne/paper laminate embossed with the illustrated longitudinal and transverse corrugatiolls and secured around the core by a conventional lapped and stuck se~n~; it may also be adliered to the core along one or more longitudi.nal gum-limes. Impermeable wrapper 6 ~loes not compress the core or impress its pattern into its surface.
The plug 2 may be of any conventional smoke ~ilterin~
material, e.g. bonded or unbonded fibres or continuous filamentary '75~3 tow (e.g. of cellulose acetate, Vi5c0~,polyester or polyolefin), creped paper, foamed plastics etc. Where plug 2 i5 itself ~
dimensionally stable bocly (e.g. a cured bonded continuous filamentary cellulosc acetate towl, and flow of smoke between core and passages 14 is to be permitted, the plug~rap 4 may be omitted. Where pluc; 2 is a composite of two or more abutting or longitudinally spaced elements, a pluc~wrap 4 may be preferred.
As indicated above, the filter may be attached to a tobacco rod either at end 18 or at end 22. In the former case, drawing on the ~outh end 22 causes external air to flow in through perforations 20, along passages 16 to the end 18 of the filter, and therl thlough the body of the filter from end 18 to end 22, diluting the smoke passing through the filter. When end 22 of the filter abuts the tobacco rod, drawing on the mouth end 18 causes external air to pass through perforations 20 and along passages 16 to the mouth end 18 so that-the ventilating air passes directly into the smokers mouth before mixincJ with the inhaled smoke. Where plugwrap 4 is omitted or is perforate and/or inherentiy smoke-permeable~
smoke will pass, in use of the filter, from the plug ~ into passages ZO 1~ and thence directl~ into the.smo~ers ~!OUtil. ~wllell ~ilter end 22 is attached to the tobacco rodl or direct].y ;.nto passacJes 1.4 atlCI
thence into the smokers mouth via pluy 2 (when end 18 is attaclled to the tobacco rodl. Where pl.uywrap 4 is of permeablc! filterinc, Imaterial, e.cJ. paper, this can enhance the tota]. particulate retentiorl of the filter.
The filters and elements of Figs.4 to 6 are similar in structure to thdt oi Fic~ure 1 and their a~pearance. in cross-secti.onal view through the circurnferentially and lonyii:udinally groovcd portions is simi.lar to that shown i.n Figures 2 and 3 res~cctivelY.
.3 IJ1 Figure 4 the plug 2 has a porous plu~rap 4 whi~h is of low initial pressure drop to allow passage of smoke but which i5 readily bloc~able by components of tne tobacco smoke; the filter is attached at end 18 to a wrapped tobacco rod 23. On smokiny the illustrated cigarette, the initial puffs result in appreciable by-pass of smoke a].ong passage 14, the degree of by-pass reducing as the wrapp2r becomes blocked so that on subsequent puffs more of the smoke is obliged to traverse the full length of the filter plug 2.
This arrangement helps to even out the taste delivery over the 10 -,~ing o the cigarette. The taste delivery of a conventional ver.tilated filter cigarette increases during smoking from a low,often unsatisfying initial value to a high, often unacceptable, level; for a given overall delivery the Fig.~ type of filter gives in comparison an increased initial and reduced final value and hence a more even lS smoke.
In the Figure 5 embodiment, plug 2 is a composite of two elements 24 and 26 of different filtering characteristics. For example, element 24 may be of high pressure drop and elemellt 26 of low ~ressure drop; in this case the plugwrap 4 is of naturally porous material and~or ~las perfolatlons at least around the low pressure drop element 26, and the ~ilter is attac}led to the wrapped tobacco rod 23 at end 18 so that the high pressure drop element 24 is against the tobacco. On initial smo};ing, smoke is thus encouraged to by-pass the high pressure drop element 24 by passing along passages ]4 into the low pressure drop element 26. As with the previouS embodiment,the plug~rap 4 may be re~dily blockable so that the degrce ~f smoke by-pass varies duLing smoking of the cigarette. The indi-idual segments can be different and chosen to give the required overall t~,J~j ~3 filtering characteristics.
In the Figure 6 embodiment, where again the filter ls attached to the tobacco rod at end lS, the plugwrap 4 is of impermeable material provided with perforations 29 at the closed ends oE the grooves 14. The plug 2 may be unitary, or could agai be a composite of a high pressure drop element adjacent to the tobacco and abutting a low pressure drop element surrounded by the perforations 29. On initial puffs, smoke from the tobacco rod passes along passages 14 and through perforations 29 into the plug
~ rhis invention relates to smoke filtration, especially tobacco smoke filtration. It provides filters and elements which are widely applicable for smoke and other filtering uses, but which are discussed and illustrated herein mainly in terms of cigarette filters, this being the application of currently greatest commercial interest. The invention provides a smoke filter element comprising a filtering core, a smoke impermeable wrapper in surrounding engagementwith the core, at least one (internal) passage defined between the impermeable wrapper and core and open at an end of the element, and at least one further (external) passage defined by the outer surface of the impermeable wrapper and extending to an end of the element. Suitably the impermeable wrapper is profiled to provide the internal and external passages, e.g. it may be longitu~;n~lly grooved or corrugated to provide the said passages;
accordingly the invention also provides a smoke filter element comprising a filtering core, and a corrugated smoke impermeable wrapper dPf;n;ng first tinternal) passages between the wrapper and core which extend longitudinally to an end of the element and further (external) passages externall~ of the wrapper which extend ~ongitu~;n~lly to an end of the element.
Elements according to the invention are intended primarily for use as filters with tipping material which provides, when the filter is drawn on in use, for the ingress of external air laterally theretHrough into the further (external) passages. Such ventilating tipping material may be applied around the impermeable wrap er as a step in the filter manufacturing procedure, or it may be the tipping ',~,,; ~
.
'o'~
overwrap whlch is applied to join element to tobacco rod in the manufacture of filter cigarettes. Accordingly the invention further provides a cigarette filter comprising a filtering core, a smoke - impermeable wrapper in surrounding engagement with the core, tipping material in surrounding engagement with the impermeable wrapper, at least one (internal) passage defined between the impermeable wrapper and core and open at an end of the filter, and at least one further (external) passage defined between the impermaable wrapper and tipping material and open at an end of the filter, the tipping material providing, when the filter is drawn on in use, for the ingress of external air laterally therethrough into said further texternal) passage(s).
The passages may extend only partially the length of the element or filter but one, more, or all can instead extend from one element or filter end to the other; any given passage may be of substantially constant cross-section along its length, or could (especially if it extends from end to end of the filter or element) be constricted over a t~rm; n~l and/or intPrr~ te region. The passages may extend axially of the element or filter or follow a curved path.
Where the impermeable wrapper is formed with longitudinal grooves or corrugations to provide said passages, the grooves or corrugations may thus extend the full wrapper length (though possibly with the grooves or corrugations being smaller at an end or int~rr-~;ate region), or may terminate (e.g. at an ~ncorrugated or circumferentially grooved or corrugated region) to close one or more passages (at least in the complete filter) at a t~r~;n~1 or inter-mediate portion of the wrapper. Other profiled configurations of 5~
the impermeable wrapper are possible Eor defining the said passages (e.g. dimples).
In particularly preferred embodimen-ts of the present invention, the impermeable wrapper has a circumferential groove into which at least one said external passage opens, this groove usually simultaneously closing the internal passage(s). In ilter cigarettes according to the invention employing such elements, there can be ventilation through the tipping material directly into the circumferential groove and hence into the communicating external paSsage(s);~or example~ventilating perforations may be provided in the tipping material in a circumferential ring in register with the circumferential groove. Various configurations are possible; for example, the circumferential groove may be disposed mid-way along - the wrapper, with internal and external passages extending therefrom in opposite directions to both ends of the element; or the circum-ferential groove may be towards one end of the element where the impermeable wrapper is circumferentially corrugated or otherwise conformed to close the circumferential groove from that end, the internal and external passages extending from the circumferential groove to the other end of the element; in another variant, the circumferential groove is at one end G~ the wrapper, being open to that end with the internal and external passages extending therefrom to the other end; other embodiments have a plurality of the circum-ferential grooves spaced along the wrapper, e.g. at opposite ends thereof~ The impermeable wrapper to be employed in the production of this type of element according to the invention can simply be pre-profiled in the normal way to provide the required passages, with each region to constitute a circumferential groove bèing left plain ~L?~ f 5;~
and unprofiled; when the profiled wrapper is applied round the core, it is found that the said plain unprofiled regions naturally adopt the conformation of circumferential grooves. This is especial].y effective in the case of corrugation to provide the passages.
When an embossed or otherwise shaped impermeable wrapper provides the said passages, the core is suitably of substantially constant circular section and the tipping material likewise in the form of a substantially right circular cylinder.
When they do not extend the fu]l wrapper length, the internal and ex-ternal passages will usually be open at the same end of the element or filter, and will usually be closed at the same position along its length, e.g. at its other end, but neither of these features is essential; the former and latter passages can be closed at different longitudinal positions each of which may be at an end of the element or filter or between its ends.
The filtering core of the element or filter of the invention can be of any of the whole range of cigarette filter materials, e.g. of bonded or unbonded staple fibres or ~ilamentary tow (of cellulose acetate, or polyolefin etc), creped paper, or air-permeable foamed matexial. The core may be of uniform or non-uniform str~cture and composition along its length; it may be integral or of composite structure - e.g. incorporating a wrapper and/or having separate plugs of the same or differing characteristics ~e.g. pressure drop) and/or composition; the core may extend wholly or only partially the length of the element or filter, and where the core is a composite of two or more plugs adjacent plugs may abut or be spaced apart. The core may be unwrapped or include a plugwrap which is perforate and/or of inherently smoke-permeable material; the core could instead have an impermeable plugwrap or integral (e.g. heat-or solvent-fused) skin. ~he core may incorporate particulate additive uniforr~lly dispersed therethrough or localised in at least one region or inter-plug space; the core may have a profiled (e.g.
longitudinally grooved) periphery, and it may have one or more internal passages or cavities which may be~filled or unfilled. The core may include one or more components which do not have a filtering effect but which merely serve to increase the pressure drop; and there may be used as or in the filtering core of elements and filters according to the invention a high pressure drop, low retention plug oÇ gathered coarse fibres or of gathered embossed plastics, metal (e.g. aluminium) or other foil. In some embodiments the impermeable wrapper surrounds a cavity or recess open at an end of the filter elernent or filter, and in use such a recess or cavity may be disposed against the wrapped tobacco rod or exposed at the buccal end of the - filtered cigarette.
Whilst the filtering core of elements according to the invention may be a composite structure as mentioned above, e.g. made up of abutting or longi~u~;n~lly spaced plugs, the profiled imperm-eable wrapper which extends the full element length renders the element overall a coherent, unita^y structure.
The impermeable wrapper is suitably a paper/thermoplastics polymer larninate, e.g. a paper/thermoplastics/paper laminate, the plastics layer preferably being of polyolefin, e.g. polyethylene.
Such a laminate has good ernbossing characteristics and retains its impermeability and embossed configuration well. The impermeable wrapper is preferably secured around the core by way of a lapped and stuck seam; it may also or instead be secured to the core by one or rj ~3 more longitudinal adhesive lines.
The tipping material may be air-permeable, but when it is the tipping overwrap ~oining the element to a tobacco column it is more usually of substantially impermeable material having perforations in open communication with the said further passages. The element may have a wrap of air~permeable material, giving a filter of plain external appearance and around which the tipping overwrap (or ring tipping) is engaged in filter cigarette manufacture, but this is not usually necessary.
In use as part of a filtered cigarette, the filter according to the invention can provide (via the internal passage(s) between impermeable wrapper and core) for some by-pass of smoke around part of the core length, various controlled effects being thereby obtainable according to the filter structure adopted as illustrated in some of the speciric em~odiments described below; in these cases, of course, the core does not have a smoke-impermeable layer between itself and the ;mpP --hle wrapper. The external passage(-s), between impermeable wrapper and tipping material, may be open to the buccal end and such that ventilation air is drawn thereinto and passes directly into the smokers mouth with little or no previous mixing with smoke. An external passage may - instead open at the tobacco rod end and be such that ventilation air drawn thereinto passes upstream to the toabcco rod and then downstream through the filter core. Constriction of a passage may affect or determine the degree and direction of flow in its unconstricted portion(s). A filter according to the invention may ha~e at least one external passage open only at the buccal end and at least another such passage open only at the other end; likewise, at least one . .
'7S~
internal passa~e ~ay open only at the buccal end and at least one other open only a-t the other end.
Elements according to the invention are suitably made by first forming the core (as a continuous or discrete finite length rod), profiling (e.g. corrugating) the impermeable wrapper to the ,required conflguration, and wrapping and securing the profi]ed ~ hle wrapper around the core; tipping material may subsequentlY
be wrapped around the impermeable wrapper; this tipping material may ,be the tipping overwrap which is employed to join element and tobacco rod together during formation of filter cigarettes in conventional manner.
Normally the core will be formed as a con-tinuous rod which is then continuously wrapped in the pre-profiled impermeable wrapper, the resu3ting continuous composite then being cut transversely into finite lengths. A wrap of air-permeable material may if desired be applied continuously around the composite of core and profiled wrapper before the cutting into finite lengths. For filter cigarette manufacture, a double length such product is disposed with a wrapped tobacco rod abutting either end, ventilating tipping over-wrap is ap,plied to join the tobacco rods and intervening element orfilter rod together, and the resulting comDination is cut in half to produce two filter cigarettes. The initially produced continuous filter or element is normally cut into even multiple (e.g. sextuple) length units for supply to the filter cigarette manufacturer who then cuts these multiple lengths into double lengths for use in filter cigarette production as described above. It will be appreciated that, in the case of individual filter or element lengths according to the invention in which the internal and external passages extend from one end only to terminate short of the other end so that the two '5.~
filter o~ element ends are different, the initial even multiple length rods supplied by the filter manufacturer and from which the individual lengths are eventually formed can have identical ends -e.g. the even multiple length rod could have passages extending from both ends or closed at both ends, according to whether the passageS
in tha final filter cigarette are to be open to the tobacco or at the buccal end respectivel~. Such double and multiple length rods also form part of the present invention.
The impermeable wrapper preferably exerts substantially no radial compression on the core and preferably does not impress its profiled configuration into the core surface. The ;mpprm~hle wrapper is prferably pre-profiled with longitll~i n~l ly extending grooves or corrugations; these may be discontinuous, with longitud-inally grooved or corrugated lengths spaced apart by portions (e.g.
plain or transversely corrugated or grooved) which in the finished filter close off longitudinal passages provided by the wrapper.
Instead of corruga-tions, the impermeable wrapper could be embossed with dimples to provide in the finished product a network of random or ordered passages, the dimpled lengths of the wrapper again optionally being spaced apart by segments which are plain or configured so as to close off passages in the finished product.
Embodiments of the invention are described below, by way of example only, with reerence to the accompanying schematic drawings tnot to scale), in which like reference numerals denote like parts and in whlrh :- -Figure 1 is a longitudinal sectional view on line I-I of Fig.3 of a filter and element according to the invention incorporated in a filter cigarette according to the invention;
S~3 Figure 2 is a ~rag~PIltary sectiQnal view of the Fig.l element and filter taken on lines II-II of Fig.l;
Figure 3 is a sectional view of the Fig.l filter and element taken on lines III-III of Fig.l;
Figures ~ to 8 are longitudinal sectional views, similar to that of Fig.l, of five further different filters and elements accordiny to the invention incorporated in respective filter cigarettes accordlng to the invention;
Figure 9 is a similar longitudinal sectional view of yet another filter and element according to the invention;
Figure 10 is an end elevation! more to scale, of the Fig.9 element and filter;
Figure 11 is a longitudinal sectional view of another element, filter and filter cigarette according to the invention;
Figuresl2 and 13 are cross sectional views along lines XII-XII and XIII-XIII respectively of Fig.ll;
Figure 14 is a perspective view of the filter element according to the invention employed in the filter of Fig.l~l;
Figure 15 is a view similar to Fig.ll of another element, filter and filter cigarette according to the invention;
Figure 16 is a perspective view of the filter element according to the invention employed in Fig.15;
Figure 17 is a view, similar to that of Fig.16, of another filter element according to the invention; and ~ Figures 18 to 20 are schematic longitudinal ~ectional views of multiple length elements according to the invention.
5.3 The ~ilter element illustrated in Figures 1 to 3 consists oE a filter core made up of a plug 2 of filtering material wrapped in a smoke-permeable (inherently smoke-permeable andJor perforate)or smoke-impermeable~ plugwrap ~, and a smoke-impermeable wrapper 6 in surrounding engagement with the core; tipping material 8 in surrounding engagement with the impermeable wrapper completes the filter. The impermeable wrapper 6 has longitudinal corrugations 10 closed at one end 22 of the filter by circumferential corrugations 12, the longitudinal corrugations 10 providing passages 14 (Fig.3) 1~ between core and impermeable wrapper and passag~ 16 between impermeable wrapper and tipping material, all of these passages beinq open at the end 18 of the filter. Tipping material 8 is of smoke~impermeable material but has a circumferential ring of perforations 20 via which passages 1~ are in communication with the external air.
Tipping material 8 is a tipping overwrap which projects beyond the core and wrapper 6 to join the element to a wrapped tobacco column 23 at end 22; it could instead join the elemen~ to such a wrapped tobacco rod at the opposite end 18.
Imperme~le wrapp~r 6 is a paper/polyethylcne/paper laminate embossed with the illustrated longitudinal and transverse corrugatiolls and secured around the core by a conventional lapped and stuck se~n~; it may also be adliered to the core along one or more longitudi.nal gum-limes. Impermeable wrapper 6 ~loes not compress the core or impress its pattern into its surface.
The plug 2 may be of any conventional smoke ~ilterin~
material, e.g. bonded or unbonded fibres or continuous filamentary '75~3 tow (e.g. of cellulose acetate, Vi5c0~,polyester or polyolefin), creped paper, foamed plastics etc. Where plug 2 i5 itself ~
dimensionally stable bocly (e.g. a cured bonded continuous filamentary cellulosc acetate towl, and flow of smoke between core and passages 14 is to be permitted, the plug~rap 4 may be omitted. Where pluc; 2 is a composite of two or more abutting or longitudinally spaced elements, a pluc~wrap 4 may be preferred.
As indicated above, the filter may be attached to a tobacco rod either at end 18 or at end 22. In the former case, drawing on the ~outh end 22 causes external air to flow in through perforations 20, along passages 16 to the end 18 of the filter, and therl thlough the body of the filter from end 18 to end 22, diluting the smoke passing through the filter. When end 22 of the filter abuts the tobacco rod, drawing on the mouth end 18 causes external air to pass through perforations 20 and along passages 16 to the mouth end 18 so that-the ventilating air passes directly into the smokers mouth before mixincJ with the inhaled smoke. Where plugwrap 4 is omitted or is perforate and/or inherentiy smoke-permeable~
smoke will pass, in use of the filter, from the plug ~ into passages ZO 1~ and thence directl~ into the.smo~ers ~!OUtil. ~wllell ~ilter end 22 is attached to the tobacco rodl or direct].y ;.nto passacJes 1.4 atlCI
thence into the smokers mouth via pluy 2 (when end 18 is attaclled to the tobacco rodl. Where pl.uywrap 4 is of permeablc! filterinc, Imaterial, e.cJ. paper, this can enhance the tota]. particulate retentiorl of the filter.
The filters and elements of Figs.4 to 6 are similar in structure to thdt oi Fic~ure 1 and their a~pearance. in cross-secti.onal view through the circurnferentially and lonyii:udinally groovcd portions is simi.lar to that shown i.n Figures 2 and 3 res~cctivelY.
.3 IJ1 Figure 4 the plug 2 has a porous plu~rap 4 whi~h is of low initial pressure drop to allow passage of smoke but which i5 readily bloc~able by components of tne tobacco smoke; the filter is attached at end 18 to a wrapped tobacco rod 23. On smokiny the illustrated cigarette, the initial puffs result in appreciable by-pass of smoke a].ong passage 14, the degree of by-pass reducing as the wrapp2r becomes blocked so that on subsequent puffs more of the smoke is obliged to traverse the full length of the filter plug 2.
This arrangement helps to even out the taste delivery over the 10 -,~ing o the cigarette. The taste delivery of a conventional ver.tilated filter cigarette increases during smoking from a low,often unsatisfying initial value to a high, often unacceptable, level; for a given overall delivery the Fig.~ type of filter gives in comparison an increased initial and reduced final value and hence a more even lS smoke.
In the Figure 5 embodiment, plug 2 is a composite of two elements 24 and 26 of different filtering characteristics. For example, element 24 may be of high pressure drop and elemellt 26 of low ~ressure drop; in this case the plugwrap 4 is of naturally porous material and~or ~las perfolatlons at least around the low pressure drop element 26, and the ~ilter is attac}led to the wrapped tobacco rod 23 at end 18 so that the high pressure drop element 24 is against the tobacco. On initial smo};ing, smoke is thus encouraged to by-pass the high pressure drop element 24 by passing along passages ]4 into the low pressure drop element 26. As with the previouS embodiment,the plug~rap 4 may be re~dily blockable so that the degrce ~f smoke by-pass varies duLing smoking of the cigarette. The indi-idual segments can be different and chosen to give the required overall t~,J~j ~3 filtering characteristics.
In the Figure 6 embodiment, where again the filter ls attached to the tobacco rod at end lS, the plugwrap 4 is of impermeable material provided with perforations 29 at the closed ends oE the grooves 14. The plug 2 may be unitary, or could agai be a composite of a high pressure drop element adjacent to the tobacco and abutting a low pressure drop element surrounded by the perforations 29. On initial puffs, smoke from the tobacco rod passes along passages 14 and through perforations 29 into the plug
2, the perforatiolls 29 eventually blocking so that more smoke is obliged to traverse the full len~h of the plug 2.
In the filter illustrated in Figure 7, the core consists of a relatively high pressure drop plug 30 abutting a relatively low pressure drop plug 32 enwrapped in and joined by a plugwrap 4 of smoke-impermeable mate ial. The impermeable wrapper 6 in this case has circumferential corrugations 12 at an intermediate region along its length, longitudinal corrugatio~s 10 extending therefrom to the opposite ends 18 and 22 of the filter. The filter i5 attached at end 1~ to ~Ira~ped tobacco rod 23 by the tipping overwrap 8, whose riny of ~entilation perforations 20 communicate with the passagf*s 16 between impermeable wrapper 6 and overwrap 8 at the buccal end 22 of the filter. At the other end of the filter the passages 1~
between im~ermeable wrapper 6 and the core are open to the tobacco.
These passages l4 extend beyond the high pressure drop plug 30, and where thcy terminate alound the upstream end of the low pressuxe drop plug 32 thc plu~rap 4 is provided with fine perforations 29 which i initially allow smoke from passages l~ to pass readily thercthrol~gh hut after a few puffs become blocked so that an increaSing a~-~un~
t^J~5 3 of smoke is obliged to travel the ull length of the core through plug 30 as well as plug 32. Not only does this give the effect obtained with the embodiments of Figs.4 to 6, but in addition the degree of air dilution into the smokers mouth via perforations 20 and passages 16 increases from a relatively low initial value (when the perforations in plu~wrap ~ are open so that the resistance to smoke flow is low) to a relatively high final value (when these perforations are blocked so that the resistance to smoke flow is at a r ~imll~); the effect is thus to level out even more the taste delivery rom first to final puff.
The Fig.8 embodiment has a filtering core made up of a plug S0 of bonded cellulose acetate f;lAm~ntary tow and an abut-ting plug 52 of creped paper, held together by a smoke-impermeable plug-wrap 4. The smoke-i.mpermeable wrapper has its longitudinal corrugations 10 e~tending the full length of the core to provide passages 14 and 16 each open at both ends of the filter. Tipping overwrap 8, of smo~e-impermeable material with a ring of perforations 2Q openi.ng into passages 16, ~oins the filter. to a wrapped tobacco column 23 and constitutes the tipping material of the ~ilter.
In t~.e en~odil~ents of Figs. l to 8, the tipping materia.l of the filter has consisted of a tipping overwrap joining the element to a wrapped tobacco rod. The tipping material of a filter according to the invention can however be a conventional plain air-permec~ble plugwrap, as illustrated in Fig.9. In t~;.s embodimentthe core is an integral fil-tering plug 2 with a smoke-per~eable plug-wrap ~, the ;m~r~ hle wrapper 6 aroulld the core having intermediate cirsumferential and ~erm~nAl longitudinal corrugations 12 and 10 respectively as in E`ig.7. Secured around impermeable wrapper 6 by a conventional lapped and stuck seam is a plain plugwrap ~o of air-permeable paper which is applied as a step in the production of the filter in continuous rod form which is then cut transversely to give the discrete filter length illustrated. Plugwrap 40 could instead be of air-impermeable material with perforations opening into passages 16. The filter may be joined at either end to a wrapped tobacco rod by means of ring tipping or a tipping overwrap having ventilation perforations communicating with passages 16 between wrapper 6 and external plugwrap 40.
It will be appreciated that, for clarity of illustration, the drawings are not to scale; in general, the radial depth of the corrugations 10 is much exaggerated and their number and the core diameter are correspondingly reduced. In practice, substantially the whole of the diameter (about 8mm) of a filter according to the invention will be taken up by the filtering core, corrugations 10 (and 12) having a radial depth of for example about 0.25 to 1 mm, e.g. 0.5 mm. Where only one peforation 20 has been shown for each passage 16, the perforations may be more closely spaced with two or more communicating with each passage 16. Fig.10 illustrates an element and filter fo the Fig.9 type more to scale, being an e;evation view of end 22. It will be seen that in practice the core plug 2 is about 8 mm. in diameter and that the corrugations 10 in wrapper 6 provide about twenty-two internal and twenty-two external passages 14 and 16, each about 0.5 mm. dee~. Similar dimensions apply in practice to the other embodiments illustrated herein in Figs.l to 9 and 11 to 20.
Whilst reference is frequently made above and below to ';'5~
the use of a corrugated impermeable wrapper, other forms of profiled impermeable wrapper are possible. For example, the impermeable wrapper could be of a heavy duty paper (e.g. of 100 g/m or more) such as cartridge paper with longitudinal grooves pre-formed therein, suitably by means of profiled impressing rollers; the surface of the paper could be left plain where the passages provided by the wrapper are to terminate.
In each of Figs.ll to 20 the filter element or rod comprises a filtering core (having a plug 2 and a plain smoke-permeable or -imp~ -~hle plugwrap 4) wrapped in a smoke-impermeable wrapper 6 with longitudinal corrugations 10 providing longitudinal passages 14 between wrapper and core and external longitudinal passages 16; in the elements of Figs.ll to 17 the impermeable wrapper also provides a circumferential groove 80 communicating with the said external grooves 16 which extend therefrom as shown to an end of the filter. In use, surrounding the filter element and joining it to a wrapped tobacco rod 23,is a ventilating tipping ovcrwrap 8 having a ring of vent;lAtin~ perforations ~0 opening into the circumferential groove.
In the embodiment of Figs.ll to 1~, internal and external passages extend longitudinally from the circumferential groove to both ends of the filter rod. In the ~o~;r^nt of Figs.15 and 16, the impermeable wrapper at the end of the filter abutting the tobacco rod has circumferential corrugations 12 which close off the circumf~rential groove and the external chAnnels from the tobacco rod, the circumferential groove being directly adjacent to t,he circumferential co~rugations and the longitudinal corrugations of the wrapper extending therefrom to the buccal end '75~3 of the filter. In the Fig.17 element, which can be incorporated in a filter cigarette in the same manner as shown for Figs.ll and 15, the circumferential groove 80 is open to one end of the element, channels 14 and 16 extending therefrom to the opposite end.
As indicated above, in the formation of the illustrated filter elements, the initially flat wrapper 6 is first embossed with its sets of corrugations 10 (Figs.ll to 14 and 17) or 10 and 12 (Figs.15 and 15) with the spaces therebetween being left plain and unembossed. When the pre-corrugated wrapper is engaged around the core 24, the unembossed wrapper portions naturally distort to provide the ciL~ relential groove 80 into which the ~hAnnP1s 16 open.
As previously explained, a filter element according to the invention such as any of those illustrated will initially be produced in a continious length from which even multiple length rods (i.e. each rod being an even multiple of the eventual individual element) are cut, the multiple length rods subsequently being further subdivided into double length elements and then, during filter cigarette production, into the final single length ~ ~ n~ ~ . Examples of sextuple length rods according to the invention, which can be further subdivided into individual elements according to the invention, are illustrated schematically in Figs.
18 to 20. Fig.18 shows a sextuple length rod from which single elements as in Fig.14 can be produced by cutting midway through the inboard longitudinally corrugated sections - firstly at po~itions 82 to yield double length rods and then, during filter cigarette manufacture as described above, at positions 84. A
si~ilar multiple length rod, but with appropriately different '5~3 dimensions of the corrugated and circumferentially grooved regions, could be cut through the corrugations and grooves to yield elements as shown in Fig.17. Fig.l9 shows a sextuple length rod which can be cut firstly at 82 midway through the inboard longitudinally corrugated regions and then at 84 midway through the circumferent-ially corrugated regions 12 to yield individual elements of the type shown in Fig.16 - in the finished filter cigarettes in this case, the filter element would be reversed compared to that in Fig. 15, with circumferential corrugations 12 at the buccal end; to produce the Fig.15 product one would start with a Fig.19 rod having the corrugations 12 at each end. Fig.20 shows a sextuple length rod which can be cut through the corrugated regions 10 and 12 to yield individual elements, filters and filter cigarettes according to the invention (e.g. Fi~ having circumferential corrugations at one end of the element with the longitudinal corrugations extending therefrom to the other end - here the filter cigarette product would have the element oriented in the same manner as shown in Fig.l, with corrugations 12 to the tobacco rod.
Whilst in all the illustrated embodiments the filtering core incorporates a plain plugwrap 4, the latter need not always be present, and when it is it may be smoke-permeable or -;~r~Pablq.
~he individual elements and multiple length rods illustrated in Figs. 14 and 16 to 20 can be provided, as part of the filter manufacturing procedure, with a plain air-permeable plugwrap. The wrapped elements or filters could then be incorpora~ed in filter cigarettes by a ventilating tipping overwrap as shown in Figs.ll and 15, or by ring tipping.
In the filter illustrated in Figure 7, the core consists of a relatively high pressure drop plug 30 abutting a relatively low pressure drop plug 32 enwrapped in and joined by a plugwrap 4 of smoke-impermeable mate ial. The impermeable wrapper 6 in this case has circumferential corrugations 12 at an intermediate region along its length, longitudinal corrugatio~s 10 extending therefrom to the opposite ends 18 and 22 of the filter. The filter i5 attached at end 1~ to ~Ira~ped tobacco rod 23 by the tipping overwrap 8, whose riny of ~entilation perforations 20 communicate with the passagf*s 16 between impermeable wrapper 6 and overwrap 8 at the buccal end 22 of the filter. At the other end of the filter the passages 1~
between im~ermeable wrapper 6 and the core are open to the tobacco.
These passages l4 extend beyond the high pressure drop plug 30, and where thcy terminate alound the upstream end of the low pressuxe drop plug 32 thc plu~rap 4 is provided with fine perforations 29 which i initially allow smoke from passages l~ to pass readily thercthrol~gh hut after a few puffs become blocked so that an increaSing a~-~un~
t^J~5 3 of smoke is obliged to travel the ull length of the core through plug 30 as well as plug 32. Not only does this give the effect obtained with the embodiments of Figs.4 to 6, but in addition the degree of air dilution into the smokers mouth via perforations 20 and passages 16 increases from a relatively low initial value (when the perforations in plu~wrap ~ are open so that the resistance to smoke flow is low) to a relatively high final value (when these perforations are blocked so that the resistance to smoke flow is at a r ~imll~); the effect is thus to level out even more the taste delivery rom first to final puff.
The Fig.8 embodiment has a filtering core made up of a plug S0 of bonded cellulose acetate f;lAm~ntary tow and an abut-ting plug 52 of creped paper, held together by a smoke-impermeable plug-wrap 4. The smoke-i.mpermeable wrapper has its longitudinal corrugations 10 e~tending the full length of the core to provide passages 14 and 16 each open at both ends of the filter. Tipping overwrap 8, of smo~e-impermeable material with a ring of perforations 2Q openi.ng into passages 16, ~oins the filter. to a wrapped tobacco column 23 and constitutes the tipping material of the ~ilter.
In t~.e en~odil~ents of Figs. l to 8, the tipping materia.l of the filter has consisted of a tipping overwrap joining the element to a wrapped tobacco rod. The tipping material of a filter according to the invention can however be a conventional plain air-permec~ble plugwrap, as illustrated in Fig.9. In t~;.s embodimentthe core is an integral fil-tering plug 2 with a smoke-per~eable plug-wrap ~, the ;m~r~ hle wrapper 6 aroulld the core having intermediate cirsumferential and ~erm~nAl longitudinal corrugations 12 and 10 respectively as in E`ig.7. Secured around impermeable wrapper 6 by a conventional lapped and stuck seam is a plain plugwrap ~o of air-permeable paper which is applied as a step in the production of the filter in continuous rod form which is then cut transversely to give the discrete filter length illustrated. Plugwrap 40 could instead be of air-impermeable material with perforations opening into passages 16. The filter may be joined at either end to a wrapped tobacco rod by means of ring tipping or a tipping overwrap having ventilation perforations communicating with passages 16 between wrapper 6 and external plugwrap 40.
It will be appreciated that, for clarity of illustration, the drawings are not to scale; in general, the radial depth of the corrugations 10 is much exaggerated and their number and the core diameter are correspondingly reduced. In practice, substantially the whole of the diameter (about 8mm) of a filter according to the invention will be taken up by the filtering core, corrugations 10 (and 12) having a radial depth of for example about 0.25 to 1 mm, e.g. 0.5 mm. Where only one peforation 20 has been shown for each passage 16, the perforations may be more closely spaced with two or more communicating with each passage 16. Fig.10 illustrates an element and filter fo the Fig.9 type more to scale, being an e;evation view of end 22. It will be seen that in practice the core plug 2 is about 8 mm. in diameter and that the corrugations 10 in wrapper 6 provide about twenty-two internal and twenty-two external passages 14 and 16, each about 0.5 mm. dee~. Similar dimensions apply in practice to the other embodiments illustrated herein in Figs.l to 9 and 11 to 20.
Whilst reference is frequently made above and below to ';'5~
the use of a corrugated impermeable wrapper, other forms of profiled impermeable wrapper are possible. For example, the impermeable wrapper could be of a heavy duty paper (e.g. of 100 g/m or more) such as cartridge paper with longitudinal grooves pre-formed therein, suitably by means of profiled impressing rollers; the surface of the paper could be left plain where the passages provided by the wrapper are to terminate.
In each of Figs.ll to 20 the filter element or rod comprises a filtering core (having a plug 2 and a plain smoke-permeable or -imp~ -~hle plugwrap 4) wrapped in a smoke-impermeable wrapper 6 with longitudinal corrugations 10 providing longitudinal passages 14 between wrapper and core and external longitudinal passages 16; in the elements of Figs.ll to 17 the impermeable wrapper also provides a circumferential groove 80 communicating with the said external grooves 16 which extend therefrom as shown to an end of the filter. In use, surrounding the filter element and joining it to a wrapped tobacco rod 23,is a ventilating tipping ovcrwrap 8 having a ring of vent;lAtin~ perforations ~0 opening into the circumferential groove.
In the embodiment of Figs.ll to 1~, internal and external passages extend longitudinally from the circumferential groove to both ends of the filter rod. In the ~o~;r^nt of Figs.15 and 16, the impermeable wrapper at the end of the filter abutting the tobacco rod has circumferential corrugations 12 which close off the circumf~rential groove and the external chAnnels from the tobacco rod, the circumferential groove being directly adjacent to t,he circumferential co~rugations and the longitudinal corrugations of the wrapper extending therefrom to the buccal end '75~3 of the filter. In the Fig.17 element, which can be incorporated in a filter cigarette in the same manner as shown for Figs.ll and 15, the circumferential groove 80 is open to one end of the element, channels 14 and 16 extending therefrom to the opposite end.
As indicated above, in the formation of the illustrated filter elements, the initially flat wrapper 6 is first embossed with its sets of corrugations 10 (Figs.ll to 14 and 17) or 10 and 12 (Figs.15 and 15) with the spaces therebetween being left plain and unembossed. When the pre-corrugated wrapper is engaged around the core 24, the unembossed wrapper portions naturally distort to provide the ciL~ relential groove 80 into which the ~hAnnP1s 16 open.
As previously explained, a filter element according to the invention such as any of those illustrated will initially be produced in a continious length from which even multiple length rods (i.e. each rod being an even multiple of the eventual individual element) are cut, the multiple length rods subsequently being further subdivided into double length elements and then, during filter cigarette production, into the final single length ~ ~ n~ ~ . Examples of sextuple length rods according to the invention, which can be further subdivided into individual elements according to the invention, are illustrated schematically in Figs.
18 to 20. Fig.18 shows a sextuple length rod from which single elements as in Fig.14 can be produced by cutting midway through the inboard longitudinally corrugated sections - firstly at po~itions 82 to yield double length rods and then, during filter cigarette manufacture as described above, at positions 84. A
si~ilar multiple length rod, but with appropriately different '5~3 dimensions of the corrugated and circumferentially grooved regions, could be cut through the corrugations and grooves to yield elements as shown in Fig.17. Fig.l9 shows a sextuple length rod which can be cut firstly at 82 midway through the inboard longitudinally corrugated regions and then at 84 midway through the circumferent-ially corrugated regions 12 to yield individual elements of the type shown in Fig.16 - in the finished filter cigarettes in this case, the filter element would be reversed compared to that in Fig. 15, with circumferential corrugations 12 at the buccal end; to produce the Fig.15 product one would start with a Fig.19 rod having the corrugations 12 at each end. Fig.20 shows a sextuple length rod which can be cut through the corrugated regions 10 and 12 to yield individual elements, filters and filter cigarettes according to the invention (e.g. Fi~ having circumferential corrugations at one end of the element with the longitudinal corrugations extending therefrom to the other end - here the filter cigarette product would have the element oriented in the same manner as shown in Fig.l, with corrugations 12 to the tobacco rod.
Whilst in all the illustrated embodiments the filtering core incorporates a plain plugwrap 4, the latter need not always be present, and when it is it may be smoke-permeable or -;~r~Pablq.
~he individual elements and multiple length rods illustrated in Figs. 14 and 16 to 20 can be provided, as part of the filter manufacturing procedure, with a plain air-permeable plugwrap. The wrapped elements or filters could then be incorpora~ed in filter cigarettes by a ventilating tipping overwrap as shown in Figs.ll and 15, or by ring tipping.
Claims (17)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A smoke filter element having opposite ends and comprising a filtering core, a smoke impermeable wrapper in surrounding engagement with the core, at least one internal passage defined between the impermeable wrapper and core and open at an end of the element, and at least one external pass-age defined by the outer surface of the impermeable wrapper and extending to an end of the element.
2. An element according to claim 1, wherein the impermeable wrapper has a profile providing the said passages.
3. A smoke filter element having opposite ends and comprising a filtering core, and a corrugated smoke impermeable wrapper defining internal passages between the wrapper and core which extend longitudinally to an end of the element and external passages externally of the wrapper which extend longitudinally to an end of the element.
4. An element according to claim 1 having such passages which extend from end to end of the element.
5. An element according to any of claims 1 to 3 having at least one such passage extending only partially the length of the core.
6. An element according to claim 4 having such pas-sages terminated or interrupted by circumferential corruga-tion of the wrapper.
7. An element according to any of claims 1 to 3, wherein the impermeable wrapper has a circumferential groove into which at least one such external passage opens.
8. An element according to any of claims 1 to 3, wherein at least one such passage has a terminal or intermediate constriction.
9. A cigarette filter comprising opposite ends, a filtering core, a smoke-impermeable wrapper in surrounding engagement with the core, tipping material in surrounding engagement with the impermeable wrapper, at least one internal passage defined between the impermeable wrapper and core and open at an end of the filter, and at least one external pas-sage defined between the impermeable wrapper and tipping material and open at an end of the filter, the tipping material having at least one perforation for the ingress of external air laterally into said external passage.
10. A cigarette filter comprising an element accord-ing to claim 3 having engaged around said impermeable wrapper tipping material which provides, when the filter is drawn on in use, for the ingress of external air laterally therethrough into said external passages.
11. A filter according to claim 9 or 10 having such passages which extend the full length of the filter to open at both ends of the filter.
12. A filter according to claim 9 or 10 having such internal and external passages which open at the same end of the filter and extend only partially towards the other end of the filter.
13. A filter according to claim 9 or 10 wherein the tipping material comprises an external plugwrap which does not extend beyond the ends of the core.
14. A filter according to claim 9 or 10 wherein said tipping material is constituted at least in part by a tipping overwrap joining the filter to a wrapped tobacco rod.
15. A filter according to claim 9 or 10 wherein the impermeable wrapper has a circumferential groove into which at least one such external passage opens and said tipping material provides, when the filter is drawn on in use, for the ingress of external air laterally therethrough directly into said circum-ferential groove.
16. A filter element rod comprising a plurality of unit elements according to claim 1, 2 or 3 disposed end-to-end and integrated by a common said impermeable wrapper extending the full length of the rod, each said unit element being disposed in mirror-image relationship to the or each integrally adjacent unit element.
17. A method of making a smoke filter element according to claim 1 which comprises forming the filtering core, profiling the impermeable wrapper to the required configuration, and then wrapping and securing the impermeable profiled wrapper around the core to provide the said internal and external passages.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8120821 | 1981-07-06 | ||
| GB8120821 | 1981-07-06 | ||
| GB8210372 | 1982-04-07 | ||
| GB8210372 | 1982-04-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1194753A true CA1194753A (en) | 1985-10-08 |
Family
ID=26280029
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000406561A Expired CA1194753A (en) | 1981-07-06 | 1982-07-05 | Smoke filter |
Country Status (18)
| Country | Link |
|---|---|
| AT (1) | AT384350B (en) |
| AU (1) | AU546687B2 (en) |
| BE (1) | BE893752A (en) |
| BR (1) | BR8203961A (en) |
| CA (1) | CA1194753A (en) |
| CH (1) | CH649448A5 (en) |
| DE (1) | DE3225091C2 (en) |
| DK (2) | DK160798C (en) |
| ES (1) | ES273648Y (en) |
| FR (1) | FR2508772B1 (en) |
| GB (1) | GB2102271B (en) |
| GR (1) | GR76553B (en) |
| HK (1) | HK86989A (en) |
| IE (1) | IE53192B1 (en) |
| IT (1) | IT1198381B (en) |
| NL (1) | NL8202557A (en) |
| NO (1) | NO157042C (en) |
| SE (2) | SE461825B (en) |
Families Citing this family (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2118424B (en) * | 1982-04-07 | 1986-07-16 | Filtrona Ltd | Tobacco smoke filter |
| JPS6048156B2 (en) * | 1982-07-07 | 1985-10-25 | 三菱アセテート株式会社 | tobacco smoke filter |
| GB2133269B (en) * | 1982-12-13 | 1986-08-20 | Filtrona Ltd | Tobacco smoke filter |
| DE3461887D1 (en) * | 1983-02-15 | 1987-02-12 | Battelle Memorial Institute | Cigarette |
| DE3445354A1 (en) * | 1983-12-13 | 1985-08-14 | H.F. & Ph.F. Reemtsma Gmbh & Co, 2000 Hamburg | Cigarette with one-piece, ventilated filter mouthpiece |
| US5509429A (en) * | 1989-03-02 | 1996-04-23 | Kothmans, Benson & Hedges Inc. | Uniform tar delivery profile filter |
| DK1321050T3 (en) | 2001-12-18 | 2007-02-12 | Bat Cigarettenfab Gmbh | Filter for a smokable article |
| GB201016387D0 (en) * | 2010-09-29 | 2010-11-10 | Filtrona Int Ltd | Tobacco smoke filter |
| GB201112466D0 (en) * | 2011-07-20 | 2011-08-31 | British American Tobacco Co | Smoking article |
| GB201213786D0 (en) * | 2012-08-01 | 2012-09-12 | Filtrona Filter Prod Dev Co | Tobacco smoke filter |
| GB201311079D0 (en) | 2013-06-21 | 2013-08-07 | British American Tobacco Co | A method of fabricating a filter element |
| GB201311450D0 (en) * | 2013-06-27 | 2013-08-14 | British American Tobacco Co | A method and an apparatus for manufacturing a filter for a smoking article |
| US11582997B2 (en) * | 2017-11-28 | 2023-02-21 | Philip Morris Products S.A. | Aerosol generating article having a mouthpiece with a modified structure |
| US20220400742A1 (en) * | 2019-10-28 | 2022-12-22 | Jt International Sa | Filter Component for an Aerosol-Generating Article |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1718122A (en) * | 1927-01-18 | 1929-06-18 | Shon Clarence L De | Cigarette tip |
| GB864247A (en) | 1958-04-16 | 1961-03-29 | Olin Mathieson | Improvements in or relating to cigarettes |
| US3490461A (en) * | 1967-04-20 | 1970-01-20 | Philip Morris Inc | Cigarette ventilation |
| US3596663A (en) * | 1969-05-29 | 1971-08-03 | Lorillard Co P | Ventilated smoking article |
| IL36205A (en) * | 1970-02-21 | 1973-05-31 | Cigarette Components Ltd | Device for treating tobacco smoke and method for its manufacture |
| SE381167B (en) * | 1974-03-13 | 1975-12-01 | Svenska Tobaks Ab | FILTER FOR TOBACCO SMOKE |
| CH621051A5 (en) * | 1976-12-15 | 1981-01-15 | Cigarette Components Ltd | Tobacco smoke filter and manufacturing process for this |
| US4256122A (en) * | 1979-04-11 | 1981-03-17 | Brown & Williamson Tobacco Corporation | Cigarette filter |
-
1982
- 1982-06-23 IE IE1500/82A patent/IE53192B1/en not_active IP Right Cessation
- 1982-06-24 NL NL8202557A patent/NL8202557A/en active Search and Examination
- 1982-06-25 DK DK287682A patent/DK160798C/en not_active IP Right Cessation
- 1982-06-29 FR FR8211358A patent/FR2508772B1/en not_active Expired
- 1982-06-30 NO NO822284A patent/NO157042C/en unknown
- 1982-07-01 SE SE8204081A patent/SE461825B/en not_active IP Right Cessation
- 1982-07-01 CH CH4012/82A patent/CH649448A5/en not_active IP Right Cessation
- 1982-07-02 GB GB08219239A patent/GB2102271B/en not_active Expired
- 1982-07-02 IT IT22208/82A patent/IT1198381B/en active
- 1982-07-02 GR GR68629A patent/GR76553B/el unknown
- 1982-07-02 ES ES1982273648U patent/ES273648Y/en not_active Expired
- 1982-07-05 DE DE3225091A patent/DE3225091C2/en not_active Expired - Fee Related
- 1982-07-05 CA CA000406561A patent/CA1194753A/en not_active Expired
- 1982-07-05 BE BE0/208525A patent/BE893752A/en not_active IP Right Cessation
- 1982-07-06 AU AU85655/82A patent/AU546687B2/en not_active Ceased
- 1982-07-06 BR BR8203961A patent/BR8203961A/en not_active IP Right Cessation
- 1982-07-06 AT AT0261682A patent/AT384350B/en not_active IP Right Cessation
-
1989
- 1989-11-02 HK HK869/89A patent/HK86989A/en not_active IP Right Cessation
- 1989-12-21 SE SE8904312A patent/SE8904312L/en not_active Application Discontinuation
-
1990
- 1990-05-10 DK DK116290A patent/DK116290A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| IT8222208A0 (en) | 1982-07-02 |
| FR2508772A1 (en) | 1983-01-07 |
| BE893752A (en) | 1983-01-05 |
| IE821500L (en) | 1983-01-06 |
| DK160798B (en) | 1991-04-22 |
| NL8202557A (en) | 1983-02-01 |
| ATA261682A (en) | 1987-04-15 |
| DE3225091A1 (en) | 1983-01-20 |
| GR76553B (en) | 1984-08-10 |
| ES273648Y (en) | 1984-08-01 |
| AU8565582A (en) | 1983-01-13 |
| SE8904312D0 (en) | 1989-12-21 |
| NO157042C (en) | 1988-01-13 |
| GB2102271B (en) | 1985-11-13 |
| GB2102271A (en) | 1983-02-02 |
| DK116290D0 (en) | 1990-05-10 |
| AU546687B2 (en) | 1985-09-12 |
| BR8203961A (en) | 1983-06-28 |
| SE461825B (en) | 1990-04-02 |
| SE8204081D0 (en) | 1982-07-01 |
| AT384350B (en) | 1987-10-27 |
| IE53192B1 (en) | 1988-08-17 |
| IT1198381B (en) | 1988-12-21 |
| DK287682A (en) | 1983-01-07 |
| NO822284L (en) | 1983-01-07 |
| SE8904312L (en) | 1989-12-21 |
| DK160798C (en) | 1991-10-14 |
| ES273648U (en) | 1984-01-16 |
| FR2508772B1 (en) | 1986-11-14 |
| HK86989A (en) | 1989-11-10 |
| DE3225091C2 (en) | 1996-09-19 |
| CH649448A5 (en) | 1985-05-31 |
| NO157042B (en) | 1987-10-05 |
| SE8204081L (en) | 1983-01-07 |
| DK116290A (en) | 1990-05-10 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |