NL8202710A - TOBACCO SMOKE FILTERING DEVICE. - Google Patents

Description

—-5

Br / Bl / lh / 14

Filtering tobacco smoke

The invention relates to tobacco smoke filters and provides such a filter which provides roads with an initially relatively low pressure drop and a relatively high pressure drop for passage of robk therethrough, the road or each of the roads having a relatively low pressure drop transverse therein provided has a barrier which is initially permeable to smoke but is thereby blocked by the passage of smoke, whereby in use the initial preferential passage of the smoke by road or roads with a low pressure drop causes a blocking thereof, so that the passage of smoke via road or roads with a high pressure drop is reinforced.

Filters according to the invention contribute to an equalization of the flavor release during the smoking of the cigarette. The flavor release of a conventional filter cigarette increases from a low, often unsatisfactory, initial value to a high, often unacceptable, value when smoked; at a given total output, a filter according to the invention provides in comparison therewith an increased initial and a reduced final value and thus a more uniform smoke.

In some preferred embodiments, said barrier consists of two layers of air-permeable sheet material (eg paper), one of which has a high air permeability (eg of 10-100 K, preferably approximately 20 K) and the other of which has an even higher air permeability ( for example 50-700 K, preferably about 500 K). The air permeability units used here are defined below.

Preferably, the barrier is applied with a layer with the higher permeability on the discharge side in the flow direction of the layer with the lower permeability; it is believed that the smoke aspirated in use spurts through the lower permeability layer, with the particulate 8202710 * * t -2-shaped phase tending to collide with the higher permeability layer, thereby advancing a progressive block. the pores of the former occur. This arrangement can provide a smoother gradual increase in pressure drop (PD) and thus a smoother conversion of the smoke flow from the roads with a low to a high pressure drop than could otherwise be achieved,

In a type of embodiment of the invention, the filter has an axially elongated core with at least one passage on its periphery extending only from one end of the core to the other end of the core and allowing in flow connection for smoke to the core via means which can be choked by passing unfiltered tobacco smoke. These members could be, for example, a barrier in the form of a core sleeve (e.g., wrap) separating the core from the or each of the passages. This core sleeve could for example consist of a smoke-permeable material with an inherently low pressure drop, which quickly becomes blocked by the passage of unfiltered tobacco smoke, so that such further flow is thereby reduced or stopped, while this core sleeve could also consist of an inherently smoke-impermeable material, having small penetrations therethrough to provide the same result, but the sleeve could also be a two-layer barrier of the above-mentioned type. Any of these passages could consist of a groove in the periphery of the core and / or bounded by opposed portions of core surface and profiled sleeve. Both the core and the sleeve can be profiled to provide this passageway (s).

In another type of embodiment, the filter has at least one internal passage extending from one end of the filter only partially to the other end thereof and a smoke connection 8202710 * 4 -3-t · with a smoke filtering portion of the filter is through organs, which can thereby be blocked by passing unfiltered tobacco smoke. These members could be, for example, a barrier layer surrounding the passage 5 and Scheldt it from the rest of the filter Scheldt, which layer initially has a low pressure drop and is permeable to the flow of smoke, but due to the flow of non-filtered terde tobacco smoke thereby blocked, so that such a flow is further reduced or stopped? the -10 may be bi-example a two-layer barrier as described above.

Some preferred filters according to the invention have longitudinally adjoining core portions with a relatively high and a relatively low pressure drop (PD) surrounded by a profiled sleeve sandwiched between the sleeve as such and the core portions. or more passages extending from one end of the filter only partially to the other, incorporating a barrier, such as the above, between the passage or passages and the low pressure drop core portion touch. The. barrier could be of the above two-layer type or 20U could instead consist of a single layer of an inherently permeable and / or pierced material. Thus, the initial low pressure drop path is provided by the low pressure drop core section, the passageway (s) and the barrier therebetween, while the high pressure drop path is provided by the low "" core sections. and high pressure drop. The core section with a high pressure drop, eg a PD of 200-600 (eg 300) mm water column, can be a plug of staple fibers or sliver (e.g., cellulose acetate) or paper. The low pressure drop core portion may be a plug or a tubular member with a lower pressure drop, which plug or which tubular member with a lower pressure drop may adjoin the core portion with a higher pressure drop or be longitudinally spaced some distance from the core portion to define a cavity, which is part of the core portion with the lower pressure drop. The said passage or passages can resp. may be in flow connection for smoke (through the barrier) with the material of the core section (the lower pressure drop) if this material is permeable to smoke) and / or | i with said cavity forming part of the core portion; with the lower pressure drop.

The core section with the higher pressure drop is suitably a plug of "Transorb" (trade name), a dense straight bar of bonded cellulose acetate filaments. The properties "Transorb" rods and methods for their preparation (which can remove the initial frizz of the elementary threads) are described in British Patent No. 970,817, at least at the discharge end thereof and in most cases throughout Length thereof, the circumference of the high pressure drop portion is preferably substantially impermeable to smoke / for example, by providing a fused (such as under the influence of heat or solvent) integral skin or of a sleeve (which has an envelope or may be a coating, for example an adhesive coating, which causes the portion to adhere to the barrier).

An air permeability of nK hereby indicates an air permeability of n x 1000 ml / min / 10 m / 100 ram 25 water column - as determined by measuring the j pressure "p" in mm.Wk / which is developed by an air flow j

2 S

of 1050 ml / min through 10 cm of the sample and calculation from the equations: 1 i [1050 x; 30 air permeability = P j

The filters according to the invention can be incorporated in filter cigarettes in the usual manner by means of a mouthpiece casing. In the above embodiments, wherein the low pressure drop portion of the filter is provided through a passage or passages from one end of the filter, this end of the filter is against the tobacco column of the filter 8202710-5 - \ t cigarette.

If the filters according to the invention are to be supplied to the production stage of. filter cigarettes are initially manufactured with an outer casing, they can be incorporated into filter cigarettes by either a mouthpiece ring or a total mouthpiece casing.

Some filters according to the invention require an outer shell to complete it, for example, to complete the formation of the road (s) 10 with a low pressure drop. According to the invention, filter elements are also provided as such to be combined with an outer casing to provide filters according to the invention. Such elements, which are exemplary of the types described below; Generally, as main elements, a main unitary or composite axially elongated core body having at least one external or internal passage extending from one end of the body to the other end generally comprises members as members. to enable a flow connection for smoke between passage (s) and body, which organs are thereby blocked by the passage of non-filtered tobacco smoke. The elements will usually be manufactured initially; - 30 - 1 1 ...... - 1 35 8202710 * -6- in the form of an endless rod and cut directly to finite lengths for further handling and production of filter cigarettes. A casing may be applied continuously around the element, if desired, while it is being formed and for cutting to finite lengths, but the resulting filters of the invention then make a further surround (surrounded with a ring or with a nozzle casing). ) for inclusion in filter cigarettes; if the elements are produced in an uncoated state, and cut, they are usually processed into filters according to the invention by applying a nozzle casing during the production of filter siglets. For the manufacture of filter cigarettes, such a double-length element or filter is placed between two naked tobacco rods, each adjacent to one end thereof, a casing is applied to connect the tobacco rods and the intermediate double element or filter and the resulting combination is cut in half to produce two filter cigarettes. The initially produced endless filter or element is usually cut to lengths of an even multiple (eg, sixfold) units for delivery to the filter cigarette manufacturer, which multiples these lengths to double lengths for use in the production of filter cigarettes, such as described above, cuts. It will be appreciated that in the case of a separate length of the filter or element of the invention that is asymmetric (ie, of which the two ends differ) the multiple and double lengths from which the individual lengths are finally formed, will usually be symmetrical and will have identical ends. Thus, the elements and filters at a multiple (including double) of the length which are thus also provided according to the invention consist of a number of unit elements or filters, which are joined together at the ends to form a whole. each unit element or filter is provided in mirror image with respect to or with respect to each unit unit forming an integral part of it or, 8202 7 1 0 * <. * -7- filter.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which like reference numerals indicate like parts, and FIG. 1 is a perspective view of a filter element according to the invention;

Fig. 2 is a partial sectional view of a filter and filter cigarette according to the invention; wherein the filter element of Fig. 1 is used; • 10 Fig. 3 is a longitudinal section through a filter cigarette in which another filter and filter element according to the invention is used;

Fig. 4 is a longitudinal sectional view taken along line IV-IV in FIG. 5 through a filter cigarette employing a third filter element and filter according to the invention;

Fig. 5 is a section along lines V-V of FIG. 4;

Fig. 6,7 and 8 are schematic longitudinal sectional views of three different filters and filter cigarettes according to the invention, the sectional view of FIG. 7 taken along lines VII-VII in FIG. 11;

Fig. 9 and 10 are cross-sectional views of the embodiment of FIG. 6 through the region of the hollow CS thereof.

Fig. 11 is a cross-sectional view of the embodiment of FIG. 7 through its front end region; and FIG. 12-14 are schematic longitudinal sectional views of three different filter elements or six-fold lengths according to the invention.

The filter element shown in Fig. 1 consists of a core 2 of bonded cellulose acetate wick with a propora sleeve 3, which is in enveloping relationship therewith.

The core 2 and the plug shell 3 are partially pruned at one end 4 to provide a core 6 of reduced cross section 8 2 0 2 7 1 0 -8, which is surrounded by four symmetrically arranged grooves or channels 8, which are ribs 10 are separated from each other. The plug casing 3 consists of porous paper which initially offers little resistance to the passage of smoke through it, but which conducts ticking is blocked by the passage of non-filtered tobacco smoke thereby. The element could be provided with a. smooth t cylindrical plug casing * 10.

The illustrated element can be manufactured by continuously manufacturing a rod of continuous acetate wick encased in plug casing 3 in a conventional manner, stringing it in at intervals and cutting the resulting constricted rod across the adjacent constricted and non-constricted portions. as explained above, this cutting would first be melted into a symmetric Multiple, then into a symmetrical duplicate, and finally into the asymmetric single lengths.

The filter element of Fig. 1 is incorporated into a filter cigarette, as shown in Fig. 2, wherein the element (shown in side view 1 with its end 4 abuts against an enveloped tobacco column 12 (shown in cross section) and is Tobacco rod attached using a nozzle casing 14 of air-impermeable material. In use, smoke is initially preferentially drawn from the tobacco rod along the low pressure drop pathway ie through channels 8 and through the plug casing. in the non-constricted part of the core 2, so the delivery of the flavor components to the smoker is relatively high *

However, after the first puffs (e.g. 3 or 4), the plug casing 35 3 becomes blocked by passing the unfiltered smoke therethrough and smoke from the tobacco column is increasingly forced to take the road with the higher pressure drop through the section 6 with the smaller cross section and along the whole __. 8202710 \ -9- length of core 2? thus, the degree of filtering the smoke increases which tends to cancel the increased release of tar, etc., which usually occurs with the later puffs of a conventional filter cigarette. Thus, a given total tar delivery can be provided at a more even rate of puffs or puff than with a conventional filter.

It will be appreciated that although an IQ wholly forming core 2 is shown, numerous variations are similar. for example, could the core be an assembly of two adjacent parts with different properties (e.g. different pressure drop)? another possibility is to provide the nozzle end of the core 2 - from an internal cavity.

The embodiment of Fig. 3 of the filter according to the invention comprises a body 20 of smoke filtering material, for example bound cellulose acetate wick, which has an air-impermeable plug casing 32 and an inner cavity 22, which is open at the end 4 thereof, A cavity 22 is separated from the surrounding body 20 by a tube wall 26 (of the same material as that of plug casing 3 of Figs. 1 and 21, which tapers into the filter, tapers to a closed end 28. Each filter according to The invention is attached at the end 4 to a sheathed tobacco rod through a mouthpiece casing 14.

The smoke path with the initially low pressure drop in this case passes through the cavity 22 and the wall 26 in the body 20, so that the tar delivery is relatively high. After a few puffs, the wall 26 becomes blocked by the passage of unfiltered smoke, so that an increasing amount of smoke must therefore run from the supply end 4 through the entire length of the body 20, so that the filtration efficiency is increased, as above. . The end 28 is constricted in the general manner, as shown in Fig. X, except that the tube of material 3 is completely closed by the constriction, the ribs 10 extending inwardly to the sealing area 28 .

8202710 -10-

The filter according to the invention shown in Figs. 4 and 5 has a core 2 consisting of an element 40 with a high pressure drop and an element 42 with a low pressure drop, which are held together by a plug casing 3. In an enveloping relationship surrounding the plug casing 3 is another air sleeve 44 of smoke and air impermeable material having longitudinally extending undulations 46 extending from the end 4 to terminate at the circumferential undulations 52 at the end 50. The corrugations 46 define longitudinally with the core 2 channels 54 which extend from the end 4 and terminate circumferentially at the corrugations 52. The propeller sleeve 3 is of the type as described above with respect to FIGS. 1 and 2. The filter includes a sleeve 14, 15 which is an external nozzle sleeve connecting the filter to its eiride 4 with the wrapped tobacco rod 12. In this case, the path for the smoke with the initially low pressure drop passes along grooves 54 through the section of the plug casing 3 at the ends of these grooves, surrounding the core member 42 with a low pressure drop and then via the latter. organ to nozzle end 50; as in the other embodiments, the initial tar is =. so release quite high. After the first puffs, plug casing 3, through which the filtered smoke passed to the low pressure drop member 42, becomes clogged and an increasing amount of smoke is forced to flow instead to the member 42 through the high pressure drop member 40 , which is accompanied by an increase in the filtering effect. The walls of the undulations 46 could be pierced 30 or have some degree of inherent permeability to a passage of smoke (during the first puffs). by enabling all channels (54 and 53) formed between the outer nozzle housing 14, the corrugations 46 and the plug housing 3.

The plug casing 3 could be replaced by a plug casing with small holes, which initially allows smoke to pass through, but then becomes blocked by it, or by a two-layer liquid casing, as described above.

8202710 v v -11-

Likewise, the tube 26 shown in Figure 3 could be replaced with a tube of the above two-layer type as plug casing (with the layer having the higher permeability on the inside), which is constricted to accommodate close the end in flow direction.

The filters of Figs. 6-11 include a vented outer shell, whereby the switchover of the smoke flow from the low pressure drop roads to high pressure drop roads in these cases is accompanied by an increase in the ventilating air flow through this casing and in the mouth of the smoker. In either case, the ventilating enclosure could be replaced by a non-ventilating enclosure.

202710 -12- __ D The filter of Figs. 6,9 and 10 has a core portion 42 with a low pressure drop, which is formed by a tube member 61 and a cavity 63, separating the tube member lengthwise from a plug 40 of tobacco smoke filtering material with a higher pressure drop. Tube member 61 may be of fibrous or non-fibrous smoke permeable or impervious material. The plug 40 suitably consists of collected elemental thread wick (e.g., from cellulose acetate) or paper with a pressure drop of about 300 mm water column. The core parts are surrounded and joined together by a sleeve 3, which forms the barrier, which is initially permeable to smoke, but is thereby blocked by the passage of the smoke. The sleeve 3 is suitably a sheath and is preferably adhered to the members 61 and 40. The sleeve 3 in this case consists of a sheath of two-ply paper, the inner layer of which faces the tobacco rod permeability of 20 K and the outer (in the direction of flow towards the nozzle end) layer a permeable

property of 500 K. However, the sleeve 3 would be out of any other 2Q

material and any other construction may exist, thereby fulfilling the described function.

Immediately surrounding the barrier sleeve 3, a profiled (for example longitudinally glued) sleeve 44 (for example of paper) is present, which may be air-permeable (but this is not the case in this case). The internal and external grooves 66, 68 provided by the sleeve 44 are open at the end SO of the filter around the plug 40 and from there extend longitudinally only 30 parts in part along the length of the filter. terminate in an area 67 around the core portion with a low pressure drop; in the region 67, the sleeve can be easily kept smooth and unprofiled, with a filler 80 (for example of thermoplastic material) filling the difference in external diameter and closing possible passages which would otherwise be open at this end of the filter to be.

For example, the internal grooves 66 may have a depth of 0.5-1 mm and a pitch of 1 mm - in which case in 8202710 v -13- a filter of conventional size would have approximately 23 grooves evenly around the circumference of the core are divided. In use, the filter may be adhered to a sheathed tobacco rod 12, as shown 5, by a vent nozzle 14, which may be inherently air permeable and / or may have vent holes (such as at 16), opening into the external passages 68. During use, tobacco smoke flows from the tobacco rod 12 during a pull through the tubular element 61. In the first pulls, at least the major part of the smoke flows through the barrier sleeve 3 into the internal passages 66 between the sleeves 3 and 44 to then move further through to the mouth of the smoker, which is the path of least pressure drop.

The smoke stream applied to the inner surface of the sleeve 3 spouts through the 20K porous paper and the particulate phase tends to collide with the 500K porous paper, gradually blocking the pores. As a result, a switchover of the smoke flow from this initial path to that through the element 40 takes place smoothly and smoothly ensuring a smooth increase in pressure drop from puff to puff.

As this gradual increase in the pressure drop from puff to puff occurs, a gradual increase in the ventilating airflow through the nozzle sleeve 14 occurs. This airflow enters the outer passages 68 and then passes through them to the smoker's mouth.

Fig. 7 and 11 illustrate another embodiment 30 in which the spaced segments 61 and 40 are similar to those used in FIG. 6 and are, as above, orphaned with an air-permeable barrier sleeve 3 of the two. layers type (inner layer of 500 K). A longitudinally corrugated sleeve 44 encloses the assembly, a circumferential groove 77 sealing the passages 66 but not the passages 68, which are blocked in the region 67 with theroplastic material 80.

...,., 8202 7 1 0 -14-

The smoke flows during use / at the | first drafts, mainly through the internal passages 66, which flow path is guided at the interruptions 77 and through the envelope 3 with the initially low pressure drop! 5 and then walks to the smoker's mouth. j

Since the envelope 3 gradually becomes clogged with particulate material of the smoke, its pressure drop gradually increases and the smoke smoothly switches to flow through segment 40 with a high pressure drop.

As in the embodiment of Figure 6, this leads to a smooth gradual increase in the pressure drop across the filter and in the filter ventilation with each subsequent draw. In modified embodiments, dilution with air is effected through the outer shell 14, in which. in case both the passages 66 and the passages 68 end at 77 (for example, through an aperture with thermoplastic material) and the seal 80 can be omitted.

Fig. 8 shows yet another embodiment, wherein a core portion 42 and a second core portion 40 are axially adjacent to each other. The section 42 is a cylinder-shaped body, which is made of porous material (for example j pc!

cellulose acetate fibers) and a very low pressure drop (preferably about 15 mm water column). The J

section 40 is a cylindrical body of porous material (eg cellulose acetate fibers) and exhibits a high pressure drop, for example of the order of 300 mm water column. 1 30

Portions 40 and 42 are enclosed by a barrier sleeve 3 of a similar construction to that of FIG. 6. The enclosure! 3, the portion 40 may be connected along its periphery. The assembly is surrounded by a longitudinally corrugated material 44 with passages 66 and 68, which i

O C I

as in FIG. 6, terminate in the region 67 near the tobacco rod. A tobacco rod 12 is attached to the filter assembly by a casing of pierced (such as at 16) or permeable nozzle paper 14. | 8202710 *, -15- ι

As shown by the arrows of the smoke spreader, the working of the filter during smoking is similar to that described in Fig. 6.

The initial smoke flow passes through the material of plug 42 and through the barrier 3 in the passages 66 but gradually switches to the road through plugs 40 and 42 as the ventilation increases through passages 68.

....

A further embodiment is provided by inversion from one end to the other end of the construction of Fig. 8, the tobacco rod 12 resting against the plug 40.

Various modifications of the illustrated embodiment are possible. For example, in the embodiments of Figures 6, 9, 10 and that of Examples VIII 3-5, the corrugated sleeve 44 may be permeable to smoke or air inherently and / or through the bores; smoke and air can thus mix in the passages 66, 68, until the passage of smoke through the barrier 3 into the passages 66 stops due to the barrier 3 becoming blocked; In these modifications, both passages 66 and 68 remain available throughout the smoking of a cigarette for the ventilating airflow, which can thus be increased compared to the case where only the external passages j (

-For the airflow can be used. * I

Furthermore, in all Figs. 6-8, the outer casing (outer nozzle casing 14 may be non-ventilating, with the switchover of the smoke stream from the low pressure drop road to a high pressure drop road from puff to poke Further, in the absence of air dilution hero, the embodiments of FIGS. 6 and 8 may otherwise remain substantially as already described regardless of whether or not the casing 44 is permeable or punctured, but in the embodiment of FIG. 7, as already mentioned, the groove 77 should be stopped 35 while the seal 80 may be absent - in which case the casing 44 could be smoke-permeable or pierced In all embodiments shown and / or described, whether or not with dilution with air, the orientation of the filter element with respect to the tobacco rod could also be reversed with the end, which is now the nozzle end, against the tobacco rod rest. In some cases of such barrier 5 (for example, in the case of Fig. 8), if dilution with air takes place through the nozzle casing, the venting air will have to be forced to the tobacco end when the barrier 3 is blocked. and then through the core instead of via the initially more direct path 10 to the nozzle end.

Instead of flat fiber products of inherently smoke-permeable material, which becomes obstructed in use to switch the smoke flow from low pressure drop roads to high pressure drop roads, one can achieve the same effect plug casings with small holes. which gradually become blocked. For example, in the embodiments shown, the barrier 3 can be replaced by a plug casing of smoke impermeable material with such bores at the discharge ends of the smoke bypass passage (s).

In the embodiments shown in Figs. 4-11, the core portion 40 with a high pressure drop on the peripheral surface may be rendered impervious to smoke by an adhesive coating, affixing it to the barrier sleeve 3, but the necessary degree and I

physical degree of surface impermeability of the high pressure drop portion 40 may be provided in other ways, as noted above. j

As explained above, a filter element or filter according to the invention, such as any of the embodiments shown, will usually be initially! are manufactured as an endless length, from which bar lengths of an even multiple (i.e. each bar is an even multiple of the final discrete elements or filters) are cut, which bar lengths are further divided into multiple later to double-length elements and then during the production of filter cigarettes to finished single-length elements. j 8202710 η -17-

Examples of sixfold length bars according to the invention, which can be further divided into individual elements according to the invention, are schematically shown in Figures 12-14. Fig. 12 shows a bar sixfold in length of the elements / from which individual elements and filters, as shown in FIGS. 1 and 2, can be made by first cutting centrally through the constricted longitudinally grooved portions at the locations 82 to form of double-length bars and then during the production of filter cigarettes, as described above, at positions 84. FIG. 13 shows a sixfold length bar which can be cut first through 82 in the center through the tube members 61 and then in the middle through 84 in the high pressure drop members 40 as part of the manufacture of individual elements, filters and filter cigarettes of the type shown in FIG. 6. FIG. 14 shows a six-length bar which can also be cut at 82 through the members 42 with a low pressure drop and then at 84 through the members 40 with a high pressure drop in the manufacture of individual elements, filter and filter cigarettes of the type as shown in Fig. 8. In Figs. 13 and 14 ', the thermoplastic sealing material 80 of the end products is not shown; the material 80 could be applied locally at the appropriate locations as part of the formation of the endless rod; on the finite bars of multiple length; or on the double or single length products obtained therefrom before, [during or after incorporation into filter cigarettes. Referring to FIGS. 12-14, the shape of multiple length bars suitable for fabricating other types of elements will be included. filters and filter cigarettes according to the invention (for example those of Figures 3-5, 7 and 11) are readily apparent.

The multiple length bars can be made with one; .tangeable. plug casing, which will usually be able to be continuously applied to the initially manufactured element bar for cutting at multiple-8202710% -18- * * length; the material 80 would then necessarily have to be applied to the initial terminal ... element for coating. The resulting filters could be attached to cigarettes by means of a ring-shaped casing or a total mouthpiece casing.

The end portions of the even multiple length bars according to the invention are the portions adjacent to the tahak in the final filter cigarettes; Thus, for the embodiments of FIGS. 6-8, the initially manufactured endless rod is first cut to the length of an even multiple through the core portions 61 (FIG. 6), 40 (FIG. 7), respectively. 42 (FIG. 8), which then occur at the ends of the multiple or double length and thus are the core portions of the unit lengths to be finally obtained which lie against the tobacco in the finished filter cigarette. In order to obtain filter cigarettes with the elements in the reverse orientation, the initial endless bars are simply cut at places which are positioned longitudinally 20 with the length of a unit element relative to the above places, i.e. through the core portions 40 (fig. 6), 61 (fig. 7) resp. 40 (fig. 8).

It will be clear that, for a clear possible explanation, the drawings are at least not accurate for the major part; for example, the radial depth of the undulations 46 and 48 in FIGS. 4 and 5 is greatly exaggerated, and the number thereof and the diameter of the core are correspondingly smaller. In practice | in all embodiments where a corrugated sleeve! When the corrugations have a radial depth of, for example, about 0.25 to 1 mm, for example, for example, substantially the entire diameter (about 8 mm) of the element or filter of the invention is usually occupied by the core. 0.5 mm, as better shown in FIG. 11. While only one vent bore 16 is shown for each external passage (56 or 68), the bores may be spaced at a smaller distance from each other, so that two or more with each of these passageways. . i will be connected.

While a corrugated impervious envelope is used in Figs. 4-11, other shapes of profiled impermeable envelope are possible. For example, the impermeable envelope could consist of 2 heavyweight papers (eg, 100 g / m or more) such as cartridge paper, with channels 54, 56 (or 66, 68) forming the longitudinal grooves suitably formed herein are using profiled embossing rollers; the surfaces of the paper could be kept smooth where the passages provided by the envelope should terminate.

If the filtering core of a filter or filter element according to the invention is an assembly of. two or more core members, one or some of which need not have any filtering effect but simply provide a pressure drop - for example, in Fig. 4-11 the plug 40, these can be replaced by a non-filtering plug with circumferential- and / or internal channels to allow the smoke to pass along and / or as a result of this almost unfiltered but to develop relatively high pressure drops.

In such cases, the switchover of the smoke stream due to a low pressure drop on roads with a high pressure drop may be accompanied by a slight or no increase in filtration at all.

As indicated above, can a filter or element according to the invention have a recess or cavity at the nozzle end? for example, in Fig. 4, the core 2 can end shortly before the end 50. The road with the onyankelljk. low pressure drop can then also be in direct connection with such a recess or cavity - for example, plug 42 can be omitted in fig.

30 8202710 «v -20-

It has been noted above that multi-length element or filter rods of the invention may consist of a number of element or filter units of the invention, which are disposed at the end of connection up to and including 5, each of these element or. filter units are mirrored relative to the or each of the adjacent element or filter units formed up to one whole. However, in the case of the multi-length output formers, such as 10 shown in Figures 13 and 14 (compare with the unit lengths of Figures 6 and 8}, it will be understood that they do not have the seal 80 which forms a necessary part of the unit lengths when included in flash cigarettes According to the invention, therefore, elements and filters of multiple (and unit) length are also provided, in which there is no such seal 80 and the like, which in filter cigarettes may be necessary to ensure the required increase in dilution with air when switching the smoke stream from low pressure drop roads to high pressure drop roads.

The seal 80, if used as part; of the bars should be of multiple length, for example, could be locally applied to the barrier 3 by printing before the latter during the initial production of the endless bar around the core; -21- is enveloped; a casing could be applied, if necessary, around the obtained core and surrounding barrier composite element (preferably for cutting the continuously manufactured rod to multiple length) to protect the seal 80 on the latter during the later hahteren before and during the production of filter cigarettes.

In embodiments of the type with a profiled sleeve 44 providing longitudinal internal and external passages 10 terminating at the same location, the passages may be terminated in this manner by a corrugation of the sleeve in the circumferential direction. For example, in Figs. 6 and .8, the smooth portion of the casing 44 and the seal 80 could be replaced by a corrugation or corrugations in the casing 44 in the circumferential direction, as at 52 in Fig. 4; in Figs. 13 and 14, the smooth sections around the tube members 61 (Fig. 13} and the plugs 42 (Fig. 14) would then be replaced by corrugated circumferential sections.

Although it has sometimes been mentioned herein as a barrier as a barrier which can be blocked by the passage of unfiltered smoke, it should be noted that the invention is not limited to the cases in which the smoke in practice completely covers the barrier. unfiltered state reached. The tobacco as such always functions as a filter; in Fig. 8, some filtration necessarily occurs through the plug 42; and while in other embodiments the smoke flows directly from the tobacco to the barrier, there will often be some condensation of smoke components in front of the barrier and in fact filtering material could be provided in this section of the road, for example, in the passages 66. However, any filtering between tobacco and barrier is preferably kept at a low value, otherwise the blocking effect of the barrier may be reduced too much to provide a significant benefit.

Claims (9)

1. Tobacco smoke filter which provides roads with an initial relatively low pressure drop and a relatively high pressure drop for smoke passage thereby, the road or each of the roads having a relatively low pressure drop in the transverse direction a barrier which is initially permeable to smoke but which is thereby blocked by the passage of smoke, whereby in use the initial preferential passage of smoke by road or low pressure drop causes a blocking thereof, so that the passage of smoke by road or roads with a high pressure drop is reinforced. 2. Filter according to claim 1, characterized in that the barrier is a two-layer air-permeable sheet material, one layer of which has an air-permeability of 10 to 100 K, as defined, and the other of which has a higher air permeability than the first possession. Filter according to claim 2, characterized in that the layer with the higher permeability is located on the discharge side of the layer with the lower permeability. 4. A filter according to any one of the preceding claims, characterized by an axially elongated core with at least one passage at its periphery extending only partially from one end of the core to the other. extends and is in flow communication for the smoke with the core through a plug casing which may be blocked by the passage of tobacco smoke. 5. A filter according to any one of claims 1-3, characterized by at least one internal passage extending from one end of the filter only partially to the other end and in flow connection for smoke with a smoke filtering portion of the filter via a barrier layer that surrounds the passage and separates it from the rest of the filter and can be blocked by the passage of tobacco smoke. 6. Filter according to any one of claims 1-4, characterized by longitudinally adjoining core sections with a relatively high and a relatively low pressure drop, which are surrounded by a profiled sleeve, which is between itself and the core sections provide one or more passages extending from one end of the filter only partially to the other, with a barrier disposed between the passage or passages and the core section with the low pressure drop, which is initially smoke permeable this prevents the passage of tobacco smoke. Filter element, characterized by a filter 10 according to any one of the preceding claims without an external casing. Filter cigarette, characterized by a filter or element according to any one of the preceding claims, which is incorporated therein by means of a mouthpiece casing. A multi-length tobacco smoke filter or filter element characterized by a plurality of unit filters or elements as claimed in any one of claims 1 to 7, which are combined in the end bandage up to £ 1, each unit element or filter being mirror image 20 is relative to the or each of the unit unit or filters adjacent to one whole.