FI89325B - Cigarette and its filter - Google Patents

Abstract

The invention concerns a cigarette filter 12 which comprises a rod of filter material with an inner zone 16 accounting for 60 - 90% of the filter effect and an outer zone 18 accounting for 10 - 40% of the filter effect, the inner zone taking up 30 - 60% of the cross-sectional area of the filter. The filter is attached to a rod 10 of tobacco by means of filter tip paper 14 with holes 24 allowing air to flow into the filter. <IMAGE>

Description

89325

Cigarette and its filter Cigarette and filter

The present invention relates to filter cigarettes and filters used in such cigarettes.

Cigarette filters with different concentric zones are already known, in which an attempt has been made to control the flow of smoke. Thus, for example, FI patent application 900155, which became public on 18.07.1990, discloses a filter cigarette with a coaxial filter. The inside of the filter is surrounded by an air-impermeable cover and is surrounded by an external filter sleeve. The filter core filters more than 95% of the smoke flowing into it, while the filtration efficiency of the outer sleeve is 0-60%, especially 10-30%. The coaxial filter is associated with a coaxial cigarette, and the purpose of the combination is to radially separate the thermal zone and the aerosol generating zone.

DE patent publication 37 43 597 discloses a coaxial cigarette in which the suction resistance of the inner part is lower than that of the outer part. The filtration efficiency of the internal part is at most 40%. Similarly, GB

Application No. 2,119,221 discloses a filter in which, on the contrary, the air permeability of the outer filter part is greater than the air permeability of the inner part. No values are presented in this publication for filtering efficiency. In both solutions, the inner part of the filter is substantially separated from the outer part by air. with an impermeable wrap.

It is an object of the present invention to provide a filter and a cigarette comprising this filter so that the smoker obtains an improved subjective experience from this cigarette from which less tar is released.

2,89325

The features of the invention are defined in the appended claims.

According to the invention, the cigarette filter consists of a rod of filter material having a longitudinal inner zone corresponding to 60-90% of the filtration efficiency and an outer end zone corresponding to 10-40% of the filtration efficiency, the inner zone occupying 30-60% of the cross section of the filter rod.

Although filters that do not provide for the intake of aeration air are under consideration, aeration still enhances this beneficial effect. The filter rod may comprise an impermeable surface layer at its periphery or may be surrounded by a cover which may be a permeable or impermeable material. In addition, in use, a suction material is placed around the rod, the function of which is to attach the filter to a rod formed of combustible material, for example tobacco. In order to provide aeration, the suction material, as well as the filter cover or circumferential surface layer, if present, should have one or more permeable areas which, during normal combustion, pass through air in an amount corresponding to 10-90%, more particularly 20-80% of aeration.

A cigarette according to the invention comprises a filter as described, which is coaxially bounded and is attached to a rod formed of combustible material. The number of puffs from this cigarette shall be at least 6.

The advantages of the invention are particularly clear when the filter is longer compared to a rod made of combustible material than in conventional cigarettes. In this case, a relatively slow-burning tobacco blend is preferably used in the cigarette.

3,89325

The filter preferably makes up 25-50% of the total length of the cigarette. Preferred filters are 27-42 mm in length.

The preferred tobacco rod has a length of 40-60 mm and provides a cigarette having a number of puffs of 6-10.

The invention is further illustrated by way of example with reference to the accompanying drawings, in which Figure 1 schematically shows a cigarette according to a preferred embodiment of the invention; and Figure 2 shows a cross-section along the line II-II in Figure 1.

The cigarette of Figure 1 comprises a coated tobacco rod 10 and a filter 12. The filter 12 is attached to the tobacco rod 10 in the usual manner with absorbent paper 14, which is shown partially removed in the figures.

The filter 12 comprises an inner longitudinal filtration zone 16 of high efficiency filtration material and an outer filtration zone 18 of less efficient filtration material. Both zones extend from the mouth end of the filter 12 to the end adjacent to the tobacco rod. The outer circumferential surface of the filter 12 is made impermeable to air and smoke by the cover 20.

The holes 22 in the cover 20 and the corresponding holes 24 in the suction cup-Per 14 allow air-to-air to enter the outer filtration zone 18 during combustion.

The technical data of the preferred cigarette shown in the drawings are as follows: - cigarette length: 84 mm - cigarette diameter: 7.9 mm 4 89325

Filter: - length: 33 mm

- pressure drop: 100 mm HaO

- inner zone diameter: 5 mm - inner zone composition: Y-shaped cellulose acetate rope, 3,0 denier / fiber, total 35 000 denier; - composition of the outer zone: Y-shaped cellulose rope, 5, 5 denier / fiber, total 22 000 denier; - aeration level: 45% - total filtration power: 60%.

Tobacco rod: - length: 51 mm - weight of tobacco: 625 mg.

The characteristics of this cigarette are as follows: - TPM released: 7, 0 - nicotine released: 0,6 mg - carbon monoxide released: 8, - number of puffs: 8.

It is noted that the smoker obtains a surprisingly improved subjective flavor response from this cigarette, as well as from other cigarettes of the present invention, compared to conventional cigarettes with similar amounts of released substances and a uniform filter.

While not wishing to be bound by any theoretical explanation, it is believed that the improved flavour effect is achieved as a result of a combination of high velocity flow through the outer filter zone 18, which is enhanced by zone aeration, and efficient low velocity flow through the inner filter zone 16.

5 S 9 325

Much of the TPM aerosol is channeled at a relatively high rate through the outer filtration zone 18 because the relatively high density and low flow rate through the inner filter zone 16 prevent a significant portion from passing through the inner zone.

This is in contrast to the case of conventionally filtered smoke, which passes almost completely through the center zone of the filter because the flow rate is the same throughout the filter and because the aerating air channels into the center of the aerosol.

It is assumed that since the smoke flows at a high speed through the filters according to the invention in the vicinity of their circumference, a larger amount of smoke flavor-providing components than smoke-less components remain in the smoke than expected. In this way, the burner gets smoke from his filter with improved flavors from the filter.

With the filters and cigarettes of the invention, the smoker obtains an improved subjective impression of a cigarette that releases relatively little TPM, such as is usually associated with cigarettes that release relatively large amounts of TPM.

#

Claims (10)

A cigarette filter (12) comprising a closure of filter material with a longitudinal inner zone (16) and a peripheral outer zone (18), the outer zone (18) having a lower filter efficiency than the inner zone (16) and the inner zone (16) satisfies 30-60% of the total area of the filter rod in the transverse direction, characterized in that the properties of the zones in combination dictate that the inner zone (16) has a filter efficiency (relative to the total amount of particulate matter). - learned material (TMP) in the range 60-90% and the outer zone (18) has a filter efficiency in the range 10-40%. 2. Filter according to claim 1, characterized in that it is surrounded by a cover or nozzle paper (14) with one or more permeable areas adapted to allow ventilating air into the filter rod. 3. Filter according to claim 1 or 2, characterized in that the diameter of the inner zone (16) is 4.5-6 mm. 4. Filter according to claim 1, 2 or 3, characterized in that the filter has an axial length of 27-42 mm. 5. Filter according to any of the preceding claims, characterized in that it has an overall efficiency of at least 50%. A filter cigarette, characterized in that it comprises a bar (10) of tobacco or some other smokable material and a filter (12) according to any of the preceding claims, which filter coaxially adheres to and is fixed to the bar (10) of smokable material, the cigarette having a flare count of at least 6. Cigarette according to claim 6, characterized in that the length of the filter (12) is 25-50% of the total length of the cigarette. Cigarette according to claim 6 or 7, characterized in that the length of the filter (12) is 27-42 mm. 8 S9325 9. A cigarette according to claim 6, 7 or 8, characterized in that ventilation air can enter the filter bar (12) in an amount corresponding to 10-90% ventilation during normal smoking. 10. A cigarette according to any of claims 6-9, characterized in that the length of the bar (10) of the smokable material is 40-60 mm and the number of flares obtained from the cigarette is 6-10.