EP0499974A2 - Ventilated filter cigarette - Google Patents

Abstract

The invention relates to a ventilated filter cigarette having a triple filter or three-chamber filter, in which the first rod-side chamber contains a filter material air-permeable essentially only in the longitudinal direction and having a high puffing resistance and low tar retention, the adjoining second chamber is a central chamber partially or completely filled with adsorbent and the third chamber adjoining the latter chamber on the mouth side having an air-permeable filter material of low puffing resistance and low to medium tar retention, all three chambers being surrounded by a common wrapper which is air-impermeable per se but is provided sectionally with laser-perforated ventilation bores and also encloses the attachment region of the tobacco rod, and which is characterised in that a) the tobacco rod is impregnated with a mixture of aroma substances, b) the central chamber is filled to the extent of up to 95% with adsorbent consisting of at least 80% by volume of activated carbon having a pore volume from 0.7 to 0.8 cm<3>/g, a pore radius from 0.9 to 1 nm and a particle size distribution corresponding to a screen mesh width in the range from 177 mu m to 500 mu m, c) that the air-impermeable wrapper is perforated in the region of the central chamber and/or in a downstream part region of the first rod-side chamber in such a way that the degree of filter ventilation is 30 to 80%, d) that the first chamber filter has a puffing resistance from 0.8 to 1.6 kPa and the third chamber filter has a puffing resistance from 0.2 to 0.4 kPa.

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 approximately 5-10% by weight of a particle phase and about 90-95 wt .-% of a gas phase, of which about 2-5 wt .-% 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. This undesirable change in taste, which is recognized as a "secondary taste" or "coal taste", has been attempted to be restricted 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 brings about an up to 80% reduction in the total gas phase range solely 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 object of the invention is to propose a filter cigarette which, while maintaining a qualitatively and quantitatively good range of flavors, has 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 according to 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 flavorings 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 further a 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 of 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, however, 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 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% by volume of this activated carbon adsorbent with a pore volume of 0.7 to 0.8 cm 3 / g and a predominant pore radius of 0.9 to 1.0 nm and a particle size distribution corresponding to the mesh size of 177 μm to 500 µm (in accordance with ASTM No. 35 and No. 80 or the corresponding ISO screens). 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 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 stream smoke, better turbulence and thus better contact of the main stream smoke with the adsorbent is achieved. If, alternatively or additionally, ventilation is also made possible in a downstream portion 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 chamber-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 substantial 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 have 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 in the longitudinal direction or rolled, 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 Foils 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 pattern 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 adding additional air at the level of this middle chamber or by adding 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 also being used in the sense of a filter section. component specification Mouth-side chamber section 1 conventional filter section, consisting of crimped cellulose acetate fibers with the titers (denier): 2.5 Y / 35000 HK; Hardener: triacetin Format: 7.8 x 12 mm Draw resistance (ZW) = 0.35 kPa Chamber section 2 Format; 7.8 x 5 mm, content 80 mg Activated carbon 30 - 70 mesh Chamber-side chamber section 3 Filter section Material: multilayered, almost air-impermeable in the radial direction, air-permeable in the longitudinal direction as cellulose acetate film. Format: 7.8 x 8 mm ZW: 1.1 kPa

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%, and the consumer-relevant final pull resistance resulting from this and the listed individual pulling resistances was 0.95 kPa mm WS.

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% 6.7ml 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 CO value of about 7 ml, which is usual for conventional cigarettes of this class or this condensate content (see comparison), is clearly undercut with 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 via 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

Test cigarettes according to Example 1 were sensory-checked in comparison with the comparison cigarettes 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 checked sensory.

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 according to and according to 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 comparative cigarette for 18 representative substances averaged about 85%, e.g. 79% for acetaldehyde, 87% for HCN, 90% for acrolein.

Sensor technology (12 smoke panel members)

Despite a 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)

Ventilated filter cigarette with a triple filter or triple-chamber filter, in which the first chamber-side chamber contains a filter material which is essentially only air-permeable in the longitudinal direction and has high tensile resistance and low tar retention, the subsequent second chamber a partially or completely filled middle chamber with adsorbent and the third mouth-side chamber adjoining this chamber has an air-permeable filter material with low tensile resistance and low to medium tar retention, all three chambers being surrounded by a common, air-impermeable, but partially laser-perforated ventilation hole, which also surrounds the attachment area of the tobacco rod encloses, characterized in that a) the tobacco rod is impregnated with a mixture of flavorings that i) 10 to 500 ppm flavoring substances of the following group A consisting 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, OH, butyric acid or propionic acid ester or CH₃-O,

and ii) 0.1 to 100 ppm flavoring substances of the following group B consisting 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, OH, butyric or propionic acid or CH₃-O, and R₁ with R₂ or R₃ with R₄ can form a benzene nucleus, contains b) the middle chamber is filled up to 95% with adsorbent, which is at least 80 vol .-% of activated carbon with a pore volume of 0.7 to 0.8 cm³ / g, a pore radius of 0.9 to 1 nm and one Grain size distribution corresponding to the mesh size in the range from 177 µm to 500 µm, c) that the airtight envelope i) in the area of the middle chamber

and or ii) in a downstream portion of the first strand-side chamber

is perforated in such a way that the degree of filter ventilation is 30 to 80%, d) that the first chamber filter has a tensile resistance of 0.8 to 1.6 kPa and the third chamber filter has a tensile resistance of 0.2 to 0.4 kPa. A cigarette according to claim 1, characterized in that the tobacco rod also contains a third component in an amount up to 200 ppm of group C consisting of one or more compounds of the general formula

in which R₁ and R₂ are the same or different and are H, CH₃ or CH₃ - CH₂, is impregnated. Cigarette according to Claims 1 to 2, characterized in that the middle chamber contains aluminum oxide, meerschaum, silica gel and / or alumina as a further adsorbent. Cigarette according to claims 1 to 3, characterized in that the first chamber filter or the first filter component consists of sheet material arranged essentially parallel to one another in the form of a lamella and made of cellulose or cellulose derivative film, starch or paper film, metal or plastic film. Cigarette according to claim 4, characterized in that the filter material in the first chamber filter consists of water-swellable foils from the group of gelatin, carboxymethyl cellulose, modified starch, polysaccharides or polyoxymethacrylates or a base film coated with a swellable material. Cigarette according to claim 4 or 5, characterized in that the films in the first chamber filter in a downstream portion and in the circumferential region of the filter element in the longitudinal direction flow through channels or grooves which are air-impermeable to the retaining filter body.