EP0558166A2 - Ventilated cigarette filter - Google Patents

Abstract

The invention relates to a ventilatable filter cigarette having three chambers (2, 4, 6), the chamber (2) at the tobacco rod end having a high pressure drop and a low tar retention owing to the fact that a core (12) of air-permeable cellulose acetate fibres is surrounded by a shell (14) of virtually air-impermeable cellulose acetate fibres. <IMAGE>

Description

The invention relates to a ventilated filter cigarette according to the preamble of patent claim 1 or 5.

From DE-OS 36 35 958 a ventilated filter cigarette with a triple filter is known, in which the first core component adjoining the tobacco rod is a plastic film corrugated in the longitudinal direction, for example made of polyethylene. In this way, longitudinal channels are formed which are essentially impermeable to air in the radial direction and with which a high pressure drop with low tar retention can be achieved. A second core component is connected to the first core component, if necessary with the interposition of a central chamber having ventilation holes for introducing additional air. The second core component is accordingly arranged in a mouth-side chamber and, with a likewise relatively low tar retention, brings about a small pressure drop.

A disadvantage of the known cigarette is that the strand-side core component is not environmentally friendly, since it consists of a plastic film such as polyethylene. Another disadvantage is that the dimensionally accurate manufacture of this core component is technically complex.

The object of the invention is to further develop the known filter cigarette, which has the taste of a so-called "strong" cigarette, in such a way that all filter cores can be produced from environmentally friendly material with simple, dimensionally stable manufacture.

To solve this problem, the characterizing features of claim 1 and 5 serve in conjunction with the features of its respective preamble.

As a result, the diameter of the filter core relevant for tar retention can be reduced in such a way that there are higher flow rates of the main stream smoke in this area, with the result that the retention mechanisms of the diffusion effect and the barrier effect decrease, while those of the inertia effect increase , so that overall a lower retention is achieved than with a conventional filter. This can be achieved either through a filter core made of cellulose acetate fibers or through cannulas or channels which are formed from cellulose acetate film. Cellulose acetate can rot and is therefore environmentally friendly. The air-impermeable jacket surrounding the cellulose acetate core can also be formed from cellulose acetate fibers, which, however, compresses much more and are therefore practically air-impermeable both in the longitudinal direction and in the radial direction. Since cannulas or channels can be molded or punctured into this air-impermeable jacket made of compressed cellulose acetate fibers without additional shells, the filter material for the entire core component on the strand side is still environmentally friendly.

The cannulas or channels are arranged in the center of the first chamber, or in another embodiment they can lie on the mouth side on the circumference of the largely air-impermeable, compressed cellulose acetate fibers. The channels, which are preferably embossed on the circumference in the mouth-side part, can also be open to the outside, and are then covered to the outside by a filter covering paper. The outer channels can run straight or helical. Zigzag patterns are also conceivable. In a preferred embodiment, the middle chamber lying between the two core components is filled with activated carbon and provided with ventilation holes. The degree of filling of the middle chamber depends on the manufacturing possibilities. As a rule, the middle chamber can only be filled with an amount of activated carbon that fills the volume to 60 to 80%. The ventilation holes are produced in the usual way, for example by laser perforation, by mechanical perforation with spiked rollers, by electromechanical means by spark discharge or by using naturally porous covering paper.

From EP-PS 0 321 740 a ventilated coaxial filter cigarette with only one filter element is known, in which the jacket and the core of the coaxial filter filter the two different smoke streams flowing through them in different ways, but in each case strongly.

So far, it has not been technically feasible to direct all of the main stream smoke directly into the carbon particles of an activated carbon filter.

In its preferred embodiment, however, the main flow smoke of the cigarette according to the invention is directed into and through the sorption granulate particles of the chamber filter, which enables optimal gas phase sorption.

Basically, the use of gas phase active material leads to an undesirable change in taste. Attempts have been made to limit this disadvantage by coating the carbon particles according to DE-PS 2 527 569 or by using diaphragms made of vapor-permeable material, e.g. according to DE-OS 2 355 493.

By a combination of (a) aromatization of the tobacco rod with a mixture of flavorings from two specific groups and (b) use of a certain adsorbent and (c) enabling a certain ventilation and (d ) Combination of two filter elements, for example, achieves a gas phase quantity which corresponds to a modern cigarette in the "ultra-light" range of less than 2 mg condensate / cigarette, while the particle phase quantity of this cigarette lies in the "light" range with approximately 5 to 6 mg of condensate / cigarette was determined, and furthermore, overall a good taste without "side or coal taste" occurs. This effect - a drastic reduction in the "secondary or coal taste" - is expressly referred to in the present application.

Advantageous embodiments of the invention result from the subclaims.

Figur 1

einen schematischen Längsschnitt durch ein erstes Ausführungsbeispiel;

Figur 2

einen Schnitt entlang den Linien A-A bzw. A'-A' durch das Ausführungsbeispiel nach Figur 1;

Figur 3

einen schematischen Längsschnitt durch ein zweites Ausführungsbeispiel;

Figur 4

einen Schnitt entlang der Linie B-B durch das Ausführungsbeispiel von Figur 3;

Figur 5

einen schematischen Längsschnitt durch ein drittes Ausführungsbeispiel;

Figur 6

einen Schnitt entlang der Linie C-C durch das Ausführungsbeispiel von Figur 5;

Figur 7

einen schematischen Längsschnitt durch ein viertes Ausführungsbeispiel;

Figur 8

einen Schnitt entlang der Linie D-D durch das Ausführungsbeispiel von Figur 7;

Figur 9

einen schematischen Längsschnitt durch ein fünftes Ausführungsbeispiel;

Figur 10

einen schematischen Längsschnitt durch ein sechstes Ausführungsbeispiel; und

Figur 11

einen Schnitt entlang der Linie E-E durch das Ausführungsbeispiel von Figur 10.

The invention is explained below with reference to a drawing; show it:

Figure 1

a schematic longitudinal section through a first embodiment;

Figure 2

a section along the lines AA and A'-A 'through the embodiment of Figure 1;

Figure 3

a schematic longitudinal section through a second embodiment;

Figure 4

a section along the line BB through the embodiment of Figure 3;

Figure 5

a schematic longitudinal section through a third embodiment;

Figure 6

a section along the line CC through the embodiment of Figure 5;

Figure 7

a schematic longitudinal section through a fourth embodiment;

Figure 8

a section along the line DD through the embodiment of Figure 7;

Figure 9

a schematic longitudinal section through a fifth embodiment;

Figure 10

a schematic longitudinal section through a sixth embodiment; and

Figure 11

a section along the line EE through the embodiment of Figure 10.

In the various exemplary embodiments, the same parts are always provided with the same reference symbols.

Figure 1 shows a first embodiment in which the tobacco rod 10 is shown only hinted. The filter is connected to the tobacco rod 10 with a first chamber 2, a second chamber 4 and a third chamber 6. The first chamber 2 is also referred to as the "strand-side" chamber, the adjoining second chamber 4 also as the "middle" chamber and the third chamber 6 adjoining the middle chamber also as the "mouth-side" chamber. The three chambers 2, 4 and 6 and part of the tobacco rod 10 are surrounded by an envelope 8, which is a filter paper used in the manufacture of cigarettes. In the first chamber 2 on the strand side, the core component is formed by an air-permeable core 12 made of cellulose acetate fibers, which is permeable to the mainstream smoke. The core 12 is surrounded by a practically air-impermeable jacket 14 made of highly compressed cellulose acetate fibers, which, like the material for the core 12, can rot and are therefore environmentally friendly.

The compression of the cellulose acetate fibers of the jacket 14 is selected such that almost no mainstream smoke can flow through it. Due to the central position and the suitable choice of the core diameter 12, on the one hand a desired high pressure drop in the main flow smoke with at the same time low tar retention can be achieved, on the other hand the main flow smoke flowing through the core 12 is forced in every cigarette position by the sorbent located in the middle chamber 4 , preferably activated carbon.

In order to eliminate the above-mentioned undesirable taste impairments, certain flavorings can be applied both to the tobacco mixture and to the filter material. Details of this are described in the parallel German patent application P 41 05 500.4, to which reference is hereby expressly made.

The incoming air entering the chamber 4 through ventilation holes is mixed there with main flow smoke and then exits through the mouth-side chamber 6, which in this exemplary embodiment is identical to the first chamber 2, i.e. it also has an air-permeable core 12 made of cellulose acetate fibers, which are surrounded by an almost air-impermeable jacket 14.

Figure 2 shows a section through the first chamber 2 along the line AA. The section AA also corresponds to the section A'-A 'through the third chamber 6. The central core 12, which is circular in cross-section and made of air-permeable cellulose acetate fibers or other rotting fibers, can be seen, which is formed by the ring-shaped jacket 14 of almost air-impermeable, rotting material, preferably tightly pressed material Cellulose acetate fibers are surrounded. In this way, the mainstream smoke from the tobacco rod 10 can only flow through the central core 12. Since the cellulose acetate arranged or designed according to the invention has a low tar retention, the tar retention is relatively small in both chambers 2 and 6.

FIG. 3 shows a further exemplary embodiment, in which the core component in the mouth-side chamber 6 is formed inversely to the strand-side chamber 2. Otherwise, the filter corresponds to that of FIG. 1, ie the first and second chambers 2 and 4 correspond to those of the first exemplary embodiment. 3, the core component of the mouth-side chamber has an air-impermeable core 34 which is surrounded by an air-permeable jacket 32.

Figure 4 shows a section BB through the core component of the mouth-side chamber 6 of Figure 3. It can be seen that the air-impermeable core 34 made of, for example, compressed cellulose acetate fibers is surrounded by an annular jacket 32 made of, for example, undensified cellulose acetate fibers, which are expediently air-permeable in the longitudinal direction of the filter. As a result, the main flow smoke flowing centrally through the first chamber 2 after passing through the middle chamber 4 for entry into the mouth-side chamber 6 is expanded in a ring shape and flows outward in a ring shape in the direction of the arrows P.

FIG. 5 shows a second embodiment of the core component on the strand side, in which a central cannula 16 is molded from the nearly air-impermeable material into the body 14 'which completely fills the chamber 2. The air-impermeable body 14 'in turn consists of highly compressed cellulose acetate fibers which can rot and are therefore environmentally friendly. The mainstream smoke can practically not pass through the compressed cellulose acetate fibers neither in the axial nor in the radial direction, but must flow through the cannula 16 into the middle chamber 4.

FIG. 6 shows a section along the line CC in FIG. 5 through the strand-side chamber 2. One can see from FIGS. 5 and 6 without further ado that the main flow smoke only flows through the central channel 16 into the middle chamber 4 and impinges there on the activated carbon located therein. Another way is blocked for mainstream smoke, since the body 14 'made of compressed cellulose acetate fibers is almost impermeable to air. This results in a sufficiently high pressure drop with low tar retention.

The mouth-side chamber 6 is formed by a core component as in the exemplary embodiment according to FIG. 1, that is to say by a central core 12 made of air-permeable cellulose acetate fibers, which is surrounded by a jacket 14 of compressed and thus almost air-impermeable cellulose acetate fibers.

FIG. 7 shows a further exemplary embodiment in which the core component of the strand-side chamber 2 corresponds to that of FIG. 5, but has a plurality of channels 16 ′ in the center. The core component of the mouth-side chamber 6 is similar to that of FIG. 3, ie an almost air-impermeable core 44 is surrounded by a jacket 42 made of air-permeable cellulose acetate fibers.

Figure 8 shows a section along the line DD through the mouth-side chamber 6 of the embodiment of Figure 7. It can be seen that the compressed, almost air-impermeable core 44 made of cellulose acetate fibers has a relatively large diameter compared to that according to the embodiment of Figure 4. This indicates that the flow velocities and thus the pressure drop are easily adjustable by selecting the individual filter core cross sections. In this exemplary embodiment, too, the main flow smoke flows centrally into the middle chamber 4, in which it impacts the activated carbon loaded, for example, with flavorings according to the invention, is mixed with additional air and flows out in an annular manner through the jacket 42 of the mouth-side chamber 6.

FIG. 9 shows another exemplary embodiment in which the core component of the strand-side chamber 2 corresponds to that of FIG. 1, that is to say an air-permeable core 12 made of rotable cellulose acetate fibers is surrounded by an almost air-impermeable sheath 14 made of compressed cellulose acetate fibers. The main flow smoke thus flows centrally or centrally into the middle chamber 4 filled with activated carbon. In this chamber, as in the other exemplary embodiments, it is mixed with additional air through the ventilation holes 5 and then through a conventional mouth-side core 22 made of cellulose acetate fibers with a relatively low total titer emanate. In the mouth-side chamber 6 there is therefore a relatively low pressure drop with a low tar retention.

FIG. 10 shows a further exemplary embodiment with a chamber 2 on the strand side and a middle chamber 4 corresponding to the exemplary embodiment according to FIG. 5, but with a chamber 6 on the mouth side, which is filled with a core 14 'with peripheral channels 16' which is almost impermeable to the mainstream smoke.

FIG. 11 shows a section along the line EE through the mouth-side chamber 6 of the embodiment of FIG. 10. Here, four channels 16 'can be seen, which are molded into the outer circumference of the practically air-impermeable body or core 14' which completely fills the third chamber 6 , so that the smoke flowing in from the middle chamber 4 can only flow out at the circumference of the mouth-side chamber 6 in the direction of the arrows.

It is pointed out that the person skilled in the art can also combine the filter components of the first and third chambers 2 and 6 in a different way than is shown in the figures.

Claims (12)

Ventilated filter cigarette with a triple filter or three-chamber filter, a) in which the first, strand-side chamber (2) contains an air-permeable filter section, b) the adjoining second chamber (4) is a middle chamber filled with adsorbent and c) the third chamber (6) on the mouth side adjoining the central chamber (4) contains a further air-permeable filter section, d) wherein all three chambers (2, 4, 6) are surrounded by two common envelopes (8) which are inherently air-impermeable but partially provided with ventilation holes, one of which also surrounds the attachment area of the tobacco rod (10), characterized by e) that the filter section arranged in the first, strand-side chamber (2) has a coaxial core (12) which is permeable to the main stream smoke and which is surrounded by a jacket (14) which is almost impermeable to the main stream smoke; f) that the second chamber (4) is filled up to 95% with adsorbent, advantageously from activated carbon with a pore volume of 0.7 to 0.8 cm³ / g, a pore radius of 0.9 to 1 nm and a particle size distribution corresponding to one Mesh size in the range from 177 µm to 500 µm; and g) that the structure of the third chamber (6) is equal to that of the first chamber (2). Cigarette according to Claim 1, characterized in that the core (12) arranged in the first chamber (2) is formed from cellulose acetate fibers which are permeable to the mainstream smoke. A cigarette according to claim 1, characterized in that the third chamber (6) has a core (34) which is impermeable to the mainstream smoke and which is surrounded by an air-permeable jacket (32). (Fig. 3) Cigarette according to Claim 1, characterized in that the third chamber (6) has a core (22) made of cellulose acetate fibers which is permeable to the main current smoke and has a relatively low total titer. (Fig. 9) Ventilated filter cigarette with a triple filter or three-chamber filter, a) in which the first, strand-side chamber (2) contains an air-permeable filter section, b) the adjoining second chamber (4) is a middle chamber filled with adsorbent and c) the third chamber (6) on the mouth side adjoining the central chamber (4) contains a further air-permeable filter section, d) wherein all three chambers (2, 4, 6) are surrounded by two common envelopes (8) which are inherently air-impermeable but partially provided with ventilation holes, one of which also surrounds the attachment area of the tobacco rod (10), characterized by e) that the filter section arranged in the first strand-side chamber (2) has a cylindrical body (14 ') made of almost impermeable filter material, which completely fills the first chamber (2) and in which one or more continuous cannulas (16) or Channels (16 ') are provided; f) that the second chamber (4) is filled up to 95% with adsorbent, advantageously from activated carbon with a pore volume of 0.7 to 0.8 cm³ / g, a pore radius of 0.9 to 1 nm and a particle size distribution corresponding to one Mesh size in the range from 177 µm to 500 µm; and g) that the third chamber (6) has a core (12) which is permeable to the main stream smoke and which is surrounded by a jacket (14) which is impermeable to the main stream smoke. (Fig. 5) A cigarette according to claim 5, characterized in that the cannula (16) is arranged in the center of the first chamber (2). Cigarette according to Claim 5, characterized in that a plurality of channels (16 ') are provided in the region of the center of the first chamber (2). (Fig. 7) Cigarette according to claim 5 or 7, characterized in that the third chamber (6) has an air-impermeable core (14 '), in the outer circumference of which a plurality of continuous channels (16') are formed. (Fig. 10) A cigarette according to claim 8, characterized in that the peripheral channels (16 ') extend in a straight line in the longitudinal direction of the third chamber (6). A cigarette according to claim 8, characterized in that the peripheral channels (16 ') extend helically in the longitudinal direction of the third chamber (6). A cigarette according to claim 5 or 7, characterized in that the third chamber (6) has a core (44) which is impermeable to the mainstream smoke and which is surrounded by an air-permeable jacket (42). (Fig. 7) A cigarette according to claim 3 or 11, characterized in that the filter material of the jacket (32, 42) surrounding the air-impermeable core (34, 44) of the third chamber (6) is made of air-permeable cellulose acetate fibers or corrugated film made of cellulose acetate.

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