Note: Descriptions are shown in the official language in which they were submitted.
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~
-- 7 --
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
- 10 -
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
-- 12 --
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
- 13 -
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
5 3
- 15 -
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~
- 16 -
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
- 17 -
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
- 18 -
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.
