EP0499974B1 - Ventilated filter cigarette - Google Patents

Description

The invention relates to a ventilated filter cigarette according to the preamble main claim.

Such filter cigarettes with a triple filter or three-chamber filter, which is also referred to as a three-component filter, are known for example from DE-OS 3 635 958, which is primarily a filter with two filter elements, namely one discloses essentially air-impermeable filter element with a large pressure drop and a second air-permeable filter element with a relatively low pressure drop. In order to enable a very high degree of ventilation on the one hand and thus a reduction in the CO content without reducing the taste and pressure drop to unacceptably low values on the other hand, the possibility is also discussed of arranging the two filter elements at a distance from one another and an adsorbent such as activated carbon in the intermediate space to reduce the vapor phase components.

The total smoke of a commercially available, medium-strength filter cigarette is made up of about 5-10% by weight of a particle phase and about 90-95% by weight of a gas phase, of which about 2-5% by weight are biologically or taste-relevant. The aim is to reduce smoke in the gas phase with less organically volatile gas phase components, so that the use of adsorbents such as activated carbon would be advantageous in principle if these adsorbents did not change the taste of the cigarette smoke in an undesirable direction. Attempts have been made to limit this undesirable change in taste, which is recognized as a "secondary taste" or "coal taste", by coating the carbon particles in accordance with DE-PS 2 527 569 or by using diaphragms made of vapor-permeable material, for example in accordance with DE-OS 2 355 493.

However, such attempts have not been successful because of the complicated structure of the adsorbent material or the filter.

Another way to achieve good filters that reduce in the gas phase is with ventilated filters, e.g. achieved according to DE-OS 3 625 593, which alone causes an up to 80% reduction in the total gas phase range through the ventilation, although individual components are lowered to different extents and also an approximately 80% reduction in the total particle phase. This naturally leads to a correspondingly high loss of taste, which is also achieved by the not inconsiderable retention of the condensates. Filters of this type are suitable for extremely light cigarettes of the “ultra-light” types with a comparatively low taste volume, which can only be compensated for by a particularly high nicotine content of the tobacco mixture or in some other way.

The invention has set itself the task of proposing a filter cigarette which, while maintaining a qualitatively and quantitatively good range of flavors, a disproportionately high gas phase reduction with a condensate and Nicotine reduction enables, and in the so far usual and perceived by consumers as annoying secondary taste or so-called "coal taste" is suppressed or completely prevented.

To achieve this object, a filter cigarette of the type mentioned at the outset is therefore proposed, which is designed in accordance with the characterizing part of the main claim, particularly preferred embodiments being mentioned in the subclaims.

The combination of (a) flavoring the tobacco rod with a mixture of flavors from two specific groups and (b) using a specific adsorbent and (c) enabling a certain ventilation and (d) combining two filter elements surprisingly achieves a gas phase quantity that one corresponds to modern cigarettes in the "ultra-light" range, of less than 2 mg of condensate / cigarette, while the particle phase quantity of this cigarette according to the invention in the "light" range was determined to be about 5 to 6 mg of condensate / cigarette, and furthermore a total good taste without "side or coal taste" occurs.

Although individual features of the combination according to the invention are known in part, the combination of all these features in a synergistic manner results in the above-mentioned surprising effect.

in der R₁ bis R₄ gleich oder verschieden sind und H, CH₃, CH₃ - CH₂, OH, Buttersäureester- oder Propionsäureesterrest oder CH₃-O bedeuten.The flavoring of the tobacco rod with flavorings may be known per se, but according to the invention, a mixture of flavorings from two groups, namely one or more compounds of flavorings, is proposed for the ventilated filter cigarette with a triple filter or a three-chamber filter Group A according to the general formula

in which R₁ to R₄ are the same or different and are H, CH₃, CH₃ - CH₂, OH, butyric acid or propionic acid or CH₃-O.

These flavors are used in amounts of 10 to 500 ppm.

in der R₁ bis R₄ gleich oder verschieden sind und H, CH₃, CH₃ - CH₂ oder einen cyclischen Kohlenwasserstoffrest bedeuten, R₁ mit R₂ odere R₃ mit R₄ einen Benzolkern bilden können,
besteht. Diese Aromastoffe der Gruppe B werden in Mengen von 0,1 bis 100 ppm eingesetzt.It is also necessary to provide one or more Group B flavorings in the mixture of flavorings, where Group B consists of one or more compounds of the general formula

in which R₁ to R₄ are the same or different and are H, CH₃, CH₃ - CH₂ or a cyclic hydrocarbon radical, R₁ with R₂ or R₃ with R₄ can form a benzene nucleus,
consists. These Group B flavorings are used in amounts of 0.1 to 100 ppm.

Preferred compounds of the flavorings according to group B are the pyrazines containing more than two methyl groups.

in der R₁ und R₂ gleich oder verschieden sind und H, CH₃ oder CH₃ - CH₂ bedeuten.Other flavorings, namely additionally as a third component, those of group C in amounts up to 200 ppm, namely compounds of the general formula, can preferably be used

in which R₁ and R₂ are the same or different and are H, CH₃ or CH₃ - CH₂.

This impregnation of the tobacco rod with the aroma mixture from group A and group B and preferably additionally from group C is related to the adsorbents, which are arranged in a central chamber between two filter elements. These adsorbents should fill at least 70 to 95% by volume of the middle chamber. Furthermore, at least 80 vol .-% of this adsorbent from activated carbon with a pore volume of 0.7 to 0.8 cm³ / g and a predominant pore radius of 0.9 to 1.0 nm and a grain size distribution corresponding to the mesh size of 177 microns to 500 µm (according to ASTM sieves no. 35 and no. 80 or the corresponding ISO sieves). Because the middle chamber is not completely filled with adsorbent, the secondary air, together with the formation of the first strand-side filter element and the perforation, brings about better contact of the mainstream smoke with the adsorbent, with the corresponding selection of the components of the mixture of flavoring substances in contrast to other more biologically relevant components are less retained in the gas phase.

It is also essential that the adsorbent in the middle chamber not only with that from the first filter element the main smoke stream escaping almost linearly comes into contact, but is additionally whirled through with or from the ventilation air, which is achieved in that the air-impermeable covering by preferably continuous perforations - or online laser perforations - ventilation in the area of the middle chamber and / or previously in enables a downstream portion of the first strand-side filter component or filter chamber.

Ventilation downstream of the first strand-side filter chamber is known per se. Because the ventilation takes place in the area of the middle chamber filled with adsorbents, in addition to a dilution of the main flow smoke, better turbulence and thus better contact of the main flow smoke with the adsorbent is achieved. If, alternatively or additionally, ventilation is also made possible in a downstream section of the first strand-side chamber, the gas phase comes into even better contact with the adsorbent. The perforation, which is usually done online by laser beams, should be such that the degree of filter ventilation is 30 to 80%.

Since the first strand-side chamber contains a filter material with high tensile resistance, which essentially only allows passage of the main flow smoke in the longitudinal direction and does not allow radial distribution of the main flow smoke in this first filter element, the main flow smoke emerges from this first filter component initially in a laminar manner, then induced by ventilation air relatively swirling into the middle chamber partially filled with sorbents and increases the adsorption of the gas phase. If the perforation occurs in a downstream portion of the first strand-side filter component, which, for example, accounts for half or a third of the filter length, this is not due to the high tensile resistance and the lamella-like configuration reckon that the secondary air entering through the perforations in this section is still accompanied by considerable amounts of mainstream smoke into the chamber. This means that the main turbulence of the secondary air takes place in the peripheral area at the transition between the first filter element and the middle chamber. Preferably, of course, by appropriately designing longitudinal grooves below the perforated wrapping sheet, it is ensured that only secondary air enters these longitudinal grooves.

For this reason, it is also necessary that the first filter element has a relatively high tensile resistance of 0.8 to 1.6 kPa and, due to its preferred material design and configuration, shows a low tar retention.

The third filter element located downstream of the middle chamber with the adsorbent, on the other hand, has a much lower tensile resistance of 0.2 to 0.4 kPa and preferably consists of conventional filter material such as cellulose acetate.

The filter material in the first strand-side chamber, which is said to bring about a high tensile resistance and a lower tar retention, can consist of paper films, cellulose or cellulose derivative films cut lengthwise, cut in strips, flowed through or rolled in the longitudinal direction, or arranged in zigzag layers and flowed lengthways. Starch films, wax paper and similar films including aluminum film or plastic film or polyolefin films according to DE-OS 3 635 958 exist.

In a particularly preferred embodiment, swellable films are used, namely those made of gelatin, carboxymethyl cellulose, carboxymethylated starch or polyoxymethacrylates, it also being possible to use non-swellable carrier films which are coated with a swellable material. The films which are strongly swellable with water or made swellable by coating Films have the advantage that even small amounts of condensed moisture, which can be up to 10 mg H₂O per cigarette according to DIN 10240, increase the draft resistance in the course of smoking the cigarette, which not only compensates for the gradually decreasing draft resistance of the tobacco rod , but also an increased ventilation is made possible by increasing the tensile resistance before the perforations in the downstream ventilated partial area of the first strand-side filter component or in the ventilated middle chamber. Designed accordingly, this leads to an approximately constant gas and particle phase supply per train.

Although the first strand-side filter element already ensures a high tensile resistance due to the material or the geometrical arrangement and thus favors ventilation in the downstream portion of this first strand-side filter element, in that the "channels" or "gaps" in the peripheral region of the filter preferably with ventilation air are supplied, it is also possible to provide specially embossed channels in the peripheral part of this section, which are closed upstream, so that no main current smoke can penetrate.

The third filter component on the mouth side consists of a conventional filter element with low tensile resistance, which results in a laminar flow with low retention. This mouth-side chamber preferably contains conventional, air-permeable cellulose acetate fiber cable.

This multi-filter design, as described above, gives the line-side filter element an unusually high speed of the little filtered main flow smoke, which is divided into parallel partial flows and which in the middle chamber either by the addition of additional air at the level of this middle chamber or by the addition of additional air in the downstream portion of the first strand-side filter element A corresponding turbulence causes such that the incoming air hits the slowing main stream smoke streams first in bundled and then in swirled air jets, whereby a better gas phase reduction is created by the adsorbent. With the main electricity smoke supply per train being approximately constant at the same time, the trains achieve a constant taste without disruptive factors ("coal taste", "off taste", "off flavor").

Examples Example 1 :

The filter components, some of which are machine-made, and which are described in more detail below, were assembled by hand to form a three-chamber filter according to the invention, the term "chamber" generally being used in the sense of a filter section.

The filter sections connected by non-porous filter wrapping paper were attached by hand using conventional, non-air-permeable covering paper to machine-made "American blend" strands (ZW = 0.47 kPa) and perforated manually at the level of the filter chamber.

The degree of ventilation or air intake of the filter cigarettes produced in this way was 55%, the final pull resistance relevant to consumers resulting from this and the listed individual pulling resistances was 0.95 kPa.

Three-chamber filter cigarettes according to Example 1 were smoked in addition to machine-made reference cigarettes (mono filter cigarettes without activated carbon, but with the same tobacco mixture) in accordance with DIN 10240. In addition, the CO content was determined according to DIN draft 10248, the NO content according to the chemiluminescence method common in the cigarette industry. Analytical data Cigarette Strand weight BL ° Currently Ktr. N Ret. ° CO NO Trial 1 780 mg 55% 8.1 6.6 mg 0.55 mg 38% 4.5 ml 48.3 µl comparison 780 mg 40% 7.7 7.0 mg 0.56 mg 47% 6.7 ml 64.8 µl

With a comparatively low degree of filter retention of 38%, the data of the experimental cigarette show a dry condensate content of 6.6 mg, which is assigned to the "light" range. The usual CO value of about 7 ml in conventional cigarettes of this class or this condensate content (see comparison) is well below 4.5 ml and, like the NO value, belongs more to the "ultra-light" range, which is due to indicates a disproportionate gas phase reduction.

The gas phase reduction of the test cigarette determined by the internal method was on average about 65% compared to the comparison cigarette for 18 representative substances.

Gas phase determination method: Volatile organic matter

The cigarettes are smoked according to DIN 10240 on an RM 20 (from Borgwaldt). The particle phase is separated by means of an electrostatic smoke trap; the gas phase is collected in a glass cylinder.

The separation into individual substances is carried out by gas chromatography using a separating capillary 60 m × 0.32 mm inside diameter, coated with 0.5 μ DB-Wax (J & W, gas chromatograph 4160 from Carlo Erba).

18 representative main substances from the classes of hydrocarbons, aldehydes, ketones, nitriles, alcohols etc. are quantified and printed out in ng / cigarette (data station Spetra Physics).

Sensors

Experimental cigarettes according to Example 1 were compared with the comparison cigarettes by sensors from a tested smoking panel of 10 people. Surprisingly, this resulted in the almost complete absence of the undesired "off button" effect (10 corresponding smoke judgments in this regard), but with somewhat reduced aroma and filling values.

Example 1a:

Three-chamber filter cigarettes according to Example 1, the strands of which, however, were provided with the flavoring substances according to the invention (150 ppm flavor class A; 15 ppm flavor class B; 10 ppm flavor class C), were smoke analysis as in example 1, in addition to the same reference cigarettes and sensory checked.

The analytical-physical data were as expected as in Example 1. The sensory evaluation was carried out by the same team of experts. Finding: The experimental cigarettes were judged to be full, tobacco-like and aromatic with other equivalence to the reference cigarettes. An "off button / off flavor" effect was not found. (9 matching, 1 different smoking judgment).

Example 2:

Three-chamber filter cigarettes according to the invention were produced in accordance with Example 1a, but, in deviation from this, contained 100 mg of activated carbon 30-70 mesh in the middle chamber, and whose filter section on the strand side consisted of starch film arranged in a zigzag layer.

These multifilter cigarettes, in addition to reference cigarettes, were also smoked in accordance with those after and as in Example 1 and checked by gas chromatography and sensors. Analytical data Cigarette Strand weight BL ° Currently Ktr. N Ret. ° CO NO Trial 2 780 mg 56% 8.2 6.4 mg 0.54 mg 39% 4.2 m 47.2 µl comparison 780 mg 40% 7.7 7.0 mg 0.56 mg 47% 6.7 ml 64.8 µl

These data show K and N values comparable to those of Example 1 and expected CO / NO reductions.

The gas phase reduction compared to the comparison cigarette for 18 representative substances averaged about 85%, e.g. 79% for acetaldehyde, 87% for HCN, 90% for acrolein.

Sensors  (12 smoke panel members)

Despite the high gas phase reduction, no "off-key / off-flavor" effect was found (12 judgments). With other equivalence compared to the reference cigarette, the test cigarettes were judged to be somewhat fuller and more aromatic (10 judgments).

Claims (6)

1. Ventilated filter cigarette having a triple-action or three-chamber filter, in which the first chamber on the side of the rod contains a filter material which is air-permeable substantially only in the longitudinal direction and has a high drawing resistance and low tar retention, the adjoining second chamber is a middle chamber which is partially or completely filled with adsorbent, and the third chamber adjoining this chamber on the mouth side has an air-permeable filter material of low drawing resistance and low to medium tar retention, all three chambers being surrounded by a common envelope which is really air-impermeable but is provided sectionally with laser-perforated ventilation bores and which also surrounds the joining region of the tobacco rod, characterized in that

   a) the tobacco rod is impregnated with a mixture of aroma substances, which contains

   i) 10 to 500 ppm of aroma substances from the following group A comprising one or more compounds of the general formula

   

   in which R₁ to R₄ are identical or different and are H, CH₃, CH₃-CH₂, OH, a butyric acid ester or propionic acid ester radical or CH₃-O, and

   ii) 0.1 to 100 ppm of aroma substances from the following group B comprising one or more compounds of the general formula

   

   in which R₁ to R₄ are identical or different and are H, CH₃, CH₃-CH₂, OH, a butyric acid ester or propionic acid ester radical or CH₃-O, and R₁ with R₂ or R₃ with R₄ can form a benzene nucleus,

   b) the middle chamber is filled up to 95% with adsorbent which consists of at least 80% by volume of activated carbon having a pore volume from 0.7 to 0.8 cm³/g, a pore radius from 0.9 to 1 nm and a particle size distribution corresponding to the screen mesh width in the range from 177 µm to 500 µm,

   c) that the air-impermeable envelope is,

   i) in the region of the middle chamber
   and/or

   ii) in a part region, located downstream, of the first chamber on the side of the rod,

   perforated in such a way that the degree of filter ventilation is 30 to 80%, and

   d) the first chamber filter has a drawing resistance from 0.8 to 1.6 kPa and the third chamber filter has a drawing resistance from 0.2 to 0.4 kPa.
2. Cigarette according to Claim 1, characterized in that the tobacco rod is also impregnated with a third component in a quantity of up to 200 ppm from group C, comprising one or more compounds of the general formula

   

   in which R₁ and R₂ are identical or different and are H, CH₃ or CH₃-CH₂.
3. Cigarette according to Claims 1 to 2, characterized in that the middle chamber contains aluminium oxide, sepiolite, silica gel and/or alumina as another adsorbent.
4. Cigarette according to Claims 1 to 3, characterized in that the first chamber filter or the first filter component consists of two-dimensional material, arranged substantially mutually parallel in the manner of lamellae, of a cellulose film or cellulose derivative film, starch film or paper film, metal film or plastic film.
5. Cigarette according to Claim 4, characterized in that the filter material in the first chamber filter consists of water-swellable films from the group comprising gelatine, carboxymethylcellulose, modified starch, polysaccharides or polyoxymethacrylates or of a base film which is coated with a swellable material.
6. Cigarette according to Claim 4 or 5, characterized in that the films in the first chamber filter have, in a part region located downstream and in the peripheral region of the filter element, channels or grooves which can take a flow in the longitudinal direction and which are designed to be air-impermeable as distinct from the retaining filter body.