The invention relates to a smoking article comprising a smokable rod and a dual filter, which can provide an improved appearance from the filter end and an improved filtration ef ^¬ fect .

US 4 256 122 A discloses a cigarette including a mono filter comprising longitudinal flutes at its lateral area, which ex ^¬ tend from the mouth-sided filter end and are visible at this end. The tipping, which connects the filter to the tobacco rod and covers the flutes, is provided with ventilation holes in the region of the flutes so that the flutes are vented.

A similar design is known from US 4 708 150 A. In this case, additional ventilation holes of the filter are arranged up- stream of the flutes.

DE 34 03 281 A discloses a cigarette including a dual filter. The mouth-sided filter section comprises a cellulose acetate filter core surrounded by a non-porous wrapping provided with longitudinally extending corrugations. The rod-sided filter section includes cellulose acetate and activated carbon as an adsorbent. Both filter sections are connected to each other by a common connecting wrapper. A non-porous tipping paper forms the outermost layer and attaches the dual filter to the to- bacco rod. The flutes formed by the corrugations are vented by a plurality of ventilation holes.

In all these cases, the flutes formed at the lateral area of the mouth-sided filter region act as channels communicating, via the ventilation holes, with the ambient air so that air diluting the tobacco smoke directly enters the smoker's mouth. This might induce a less pleasant impression. Moreover, mono filters are known which comprise a plurality of flutes arranged at the lateral area of the filter. The flutes emerge from the mouth-sided end of the filter and run longitu ^¬ dinally, but do not extend up to the other end of the filter. The flutes are embossed in an inner paper wrap. An additional outer plug wrap can be standard or porous. Such filters are marketed by Essentra Filter Products under the trade name "Combined Performance Superior™ Filter". Another product marketed by Essentra, under the trade name "Combined Performance Superior™ Dual Filter", is a dual filter which comprises the mono filter mentioned before plus a rod-sided filter segment including cellulose acetate and activated carbon as an adsorb ^¬ ent. In both cases, ventilation holes are not provided. EP 2 265 137 B discloses a composite material formed of cellu ^¬ lose acetate and precipitated silica, which can be used, e.g., for liquid or gas filtration or in cigarette filters.

The object of the invention is the provision of a smoking ar- ticle that combines a distinctive appearance at the mouth- sided end with a high filtration and gas phase-reducing performance, without exhibiting the unpleasant air dilution ef ^¬ fect mentioned above. This object is achieved by a smoking article having the fea ^¬ tures of claim 1. Advantageous versions of the invention fol ^¬ low from the dependent claims.

The smoking article according to the invention comprises a smokable rod (e.g. a tobacco rod wrapped with cigarette paper) and a dual filter. The filter includes a rod-sided filter sec ^¬ tion, which comprises a filtering material and an adsorbent, and a mouth-sided filter section. The mouth-sided filter sec ^¬ tion extends from a mouth-sided first end to a second end, wherein a first lateral area starts at the first end and ex- tends up to some intermediate circumferential line, while a second lateral area extends from that line to the second end of the mouth-sided filter section. The mouth-sided filter sec ^¬ tion comprises a filtering material, e.g. cellulose acetate. A plurality of flutes (channels) is arranged at the first lat ^¬ eral area, i.e. only at the first lateral area. These flutes extend from the first end of the mouth-sided filter section and run generally longitudinally, i.e. generally in parallel to the longitudinal axis of the smoking article. A plurality of ventilation holes is arranged at the second lateral area, and the flutes are not vented by any ventilation holes ar ^¬ ranged at the first lateral area. Preferably, the dual filter does not comprise ventilation holes in addition to those ar ^¬ ranged at the second lateral area of the mouth-sided filter section.

Since the flutes start at the first end of the mouth-sided filter section, i.e. the mouth-sided end of the smoking arti ^¬ cle, they are visible at this end and provide a distinctive appearance to the smoking article. The flutes are not a part of an air ventilation system because they are not vented by ventilation holes. Therefore, the level of ventilation of the smoking article according to the invention is not affected by a squeezing of the mouth-sided filter section in use (e.g. by the smoker's lips), which might block the channels formed by the flutes.

An absence of ventilation holes in the rod-sided filter sec ^¬ tion has another advantageous effect. In this case, an in- creased air flow due to ventilation air drawn through the adsorbent-loaded filter section, which would reduce the effi ^¬ ciency of the adsorbent in the region downstream of the venti ^¬ lation zone, does not occur. In advantageous embodiments of the invention, the mouth-sided filter section comprises an inner wrapper which, in the first lateral area, defines the flutes and, in the second lateral area, is flat. That inner wrapper may be corrugated, in the first lateral area, with corrugations forming crests and val ^¬ leys, wherein the valleys are located in depressions of the filtering material of the mouth-sided filter section, thus de ^¬ fining the flutes. Moreover, the mouth-sided filter section may comprise another wrapper (in the following: plug wrap), which overlays the inner wrapper and is wrapped in a generally cylindrical shape. In this way, the corrugations and the plug wrap form channels. In the second lateral area, the plug wrap abuts the inner wrapper, generally over the total of the sec ^¬ ond lateral area. The plug wrap can be glued to the inner wrapper, wherein preferably the channels are essentially kept free from glue .

The inner wrapper may be porous. In this case, mainstream smoke diluted by air entering into the mouth-sided filter sec- tion through the ventilation holes is drawn through the filtering material of the mouth-sided filter section, but is also able to enter the channels through the porous inner wrapper, wherein it is filtered by the material (e.g., paper) of the inner wrapper before it flows downstream, largely unimpeded and without further dilution, through the flutes or channels to the smoker's mouth.

The rod-sided filter section and the mouth-sided filter sec ^¬ tion can be connected to each other by a connecting wrapper. In principle, the plug wrap mentioned before can be taken as the connecting wrapper, but preferably a further wrapper is used, which is wrapped about the plug wrap of the mouth-sided filter section and the lateral face of the rod-sided filter section when both filter sections are placed end-to-end. In this context, the filtering material and the adsorbent of the rod-sided filter section may be wrapped in an independent plug wrap as well, which constitutes the lateral face of the rod- sided filter section and is overwrapped by the connecting wrapper .

Finally, as an outermost wrapper, a tipping may be used to connect the dual filter to the smokable rod. Usually, the tip ^¬ ping is made of paper, but other materials are conceivable as well .

In advantageous embodiments of the invention, the connecting wrapper and/or the tipping are non-porous, i.e. the material used for the connecting wrapper and/or the tipping is inherently non-porous or has a very low porosity. In this case, am- bient air can enter the dual filter when used virtually exclu ^¬ sively through the ventilation holes. If the connecting wrapper and/or the tipping are non-porous, the choice of the po ^¬ rosity (e.g., high or very low) of any plug wrap will not have a particular effect.

The filter ventilation may be, e.g., at least 20% or at least 40%. Preferably, the ventilation holes are laser-perforated. Laser-perforated ventilation holes can be prepared online dur ^¬ ing manufacture of the smoking articles on a cigarette maker after a dual filter has been attached to a respective tobacco rod on a combiner and after application of a tipping. Generally, the laser beam penetrates the tipping and the connecting wrapper as well as the plug wrap and the inner wrapper of the mouth-sided filter section.

In advantageous embodiments of the invention, the adsorbent in the rod-sided filter section is a composite material contain ^¬ ing silica, e.g. prepared as porous granules containing a cel ^¬ lulose acetate/silica mixture. Such materials and the manufac- ture thereof are known from EP 2 265 137 B. Silica has good adsorbent properties, and the cellulose acetate of the gran ^¬ ules improves the adhesion of the granules inside the filter ^¬ ing material (e.g., cellulose acetate) of the rod-sided filter section .

In the following, the invention is further explained by means of an embodiment. The drawing shows in

Figure 1 a schematic three-dimensional view of an embodiment of a smoking article according to the invention, wherein the dual filter thereof is illustrated with its wrappers partially unwrapped.

Figure 1 shows an embodiment of a smoking article (designated by 1) in a schematic three-dimensional partial view.

The smoking article 1 comprises a tobacco rod 2 wrapped with cigarette paper, to which a dual filter 4 is attached. Other smokable materials than tobacco are conceivable as well. The dual filter 4 includes a rod-sided filter section 6 and a mouth-sided filter section 8.

The rod-sided filter section 6 comprises a filtering material and an adsorbent and is wrapped with an individual plug wrap, which is not shown in detail in Figure 1. In the embodiment, cellulose acetate is used as the filtering material. The ad ^¬ sorbent is silica contained in porous granules which also com ^¬ prise cellulose acetate. Such granules are known from, e.g., EP 2 265 137 Bl .

The mouth-sided filter section 8 includes a filtering material 10 (e.g. cellulose acetate) and extends from a first end 12, which is the mouth-sided end of the dual filter 4, to a second end 13. Figure 1 shows an intermediate circumferential line 14, as a dashed line, which is drawn to divide the lateral ar- ea of the mouth-sided filter section 8 into a first lateral area 16 (extending from the first end 12 to the intermediate circumferential line 14) and a second lateral area 17 (extend ^¬ ing from the intermediate circumferential line 14 to the se- cond end 13) .

At the first lateral area 16, there is arranged a plurality of depressions 20, which extend from the first end 12 and run generally longitudinally, i.e. in parallel to the longitudinal axis of the smoking article 1. However, the depressions 20 in the filtering material 10 do not cross the intermediate cir ^¬ cumferential line 14 so that they are confined to the first lateral area 16. An inner wrapper 22 is wrapped about the mouth-sided filter section 8. In the first lateral area 16, the inner wrapper 22 is corrugated with corrugations forming valleys 24 and crests 26 wherein the valleys 24 correspond to the depressions 20, while the crests 26 stay at the level of the original surface of the filtering material 10, which is the level of the generally cylindrical second lateral area 17. In the embodiment, the inner wrapper 22 is made of a porous paper .

The mouth-sided filter section 8 comprises another wrapper 28 (plug wrap) , which overlays the inner wrapper 22 and is wrapped in a generally cylindrical shape. In the embodiment, the plug wrap 28 is made of a porous paper glued to the inner wrapper 22 in the area of the crests 26 and the second lateral area 17. The glue generally does not enter the valleys 24. In this way, the valleys 24 of the inner wrapper 22 in the de- pressions 20 in combination with the overlaying parts of the plug wrap 28 form a plurality of channels (flutes) extending at the first lateral area 16 of the mouth-sided filter section In the embodiment, the rod-sided filter section 6 comprises its own plug wrap (not separately shown in Figure 1) . The mouth-sided filter section 8 and the rod-sided filter section 6 are connected to each other by a connecting wrapper (not shown in Figure 1), which facilitates the assemblage of the dual filter 4. The latter plug wrap and the connecting wrapper may be made of porous or non-porous paper.

The dual filter 4 is connected to the tobacco rod 2 by means of a tipping 30, which is glued to the outer faces of the dual filter 4 and the filter-sided end area of the tobacco rod 2. In the embodiment, the tipping 30 is made of a non-porous ma ^¬ terial or a material having a low or very low porosity, e.g. a paper material.

A plurality of ventilation holes 32 is arranged at the second lateral area 17 of the mouth-sided filter section 8, and only in this area, so that the channels or flutes defined by the depressions 20 are not vented. In Figure 1, the ventilation holes 32 are arranged on one circumferential line. Other pat ^¬ terns of ventilation holes are conceivable as well. The venti ^¬ lation holes 32 can be prepared by an online laser perforation technique and extend through all layers of wrapping, i.e. through the tipping 30, through the connecting wrapper not shown in Figure 1, through the plug wrap 28 and through the inner wrapper 22. In this way, the ventilation air directly enters into the filtering material 10.

When the smoking article 1 is used, mainstream smoke diluted by the ventilation air can stream not only through the filtering material 10 into the user's mouth, but also from the fil ^¬ tering material 10 through the porous inner wrapper 22 and via the channels defined by the depressions 20.