HK1145611A1 - Cigarette filter, and filter cigarette - Google Patents

Abstract

A single-segment filter having a filter plug uses a high-rigidity and high-permeability paper longitudinal rigidity of which is 30 or higher as measured in accordance with JIS P8143 and air permeability of which is 1000 CORESTA units or greater as a filter plug wrapper wrapping a filter material, and a multisegment filter having a plurality of filter plugs uses the high-rigidity and high-permeability paper as a filter plug wrapper wrapping a filter material and/or a shaping paper joining plurality of filter plugs. A cigarette comprises the particular filter.

Description

Cigarette filter and cigarette with filter

Technical Field

The present invention relates to a cigarette filter and a cigarette with the filter.

Background

For example, in order to relieve the smoke taste (the main taste), cigarettes with filters have been developed and put on the market. A filter-tipped cigarette is a cigarette in which a filter is provided at one end of a cigarette body, the cigarette body containing a cigarette filler rod such as tobacco shreds, and the outer periphery of the cigarette filler rod being wrapped with wrapping paper. The filter has at least one filter plug. Each filter plug includes a filter material in a cylindrical body formed of a wrapping paper (filter plug wrap) wound in a cylindrical shape (normally cylindrical shape). The filter is provided at one end of the cigarette body by tipping paper (tip paper).

For smokers, the filter hardness of a cigarette with a filter is one of the indexes for selecting a cigarette. Most of the filter cigarettes currently on the market use cellulose acetate tow (tow) as a filter material (hereinafter also referred to as cellulose acetate filter). Since sufficient filter hardness cannot be obtained by cellulose acetate fiber alone, the filter is imparted with hardness by mixing a plasticizer (triacetin or the like) thereto. It is known that triacetin is added in an amount of 5 to 10% by weight based on the weight of cellulose acetate in a cellulose acetate filter material for a cigarette with a filter which is currently commercially available.

Some smokers have satisfied the conventional filter hardness given by the above-mentioned amount of triacetin, but some smokers prefer a higher hardness filter.

In the case of a cellulose acetate filter material, it is known that the hardness of the filter can be further improved by increasing the amount of plasticizer to be added. However, if the amount of triacetin added is increased to a certain level or more, acetic acid is generated by hydrolysis of triacetin. As a result, there arises a problem that the cigarette packs (cigarette packs) are filled with acetic acid odor. In addition, in the case of using an activated carbon filter material, triacetin is adsorbed on activated carbon, and there is a problem that the function of activated carbon (adsorption of smoke components) cannot be sufficiently exhibited.

However, in the filter cigarette, in order to further dilute the mainstream smoke by allowing ambient air to flow in, it is required to increase the ventilation rate.

International publication No. 00/00047 discloses a so-called recess (access) cigarette filter having a high ventilation rate. The cigarette filter comprises 2 filter sticks each wound with porous or non-porous roll paper, and the two filter sticks are connected by non-porous wrapping paper (shaping input). The filter is mounted on the cigarette rod by tipping paper. To achieve high air permeability, larger air holes are provided on the wrapping paper and the forming paper through mechanical perforation, while smaller air holes are provided on the tipping paper through laser perforation. The formation of the ventilation holes increases the cigarette manufacturing cost, and has problems of low versatility for various smoking products including low tar cigarettes and the like, and lack of stability in terms of quality. The above problems are also pointed out in Japanese Kokai publication 2004-516814, which discloses the same recess filter.

Note that, in neither the international publication pamphlet of 00/00047 nor japanese laid-open patent publication No. 2004-516814, there is any direct description about the hardness of the filter.

Disclosure of Invention

The invention aims to provide a cigarette filter which can realize enough hardness and ventilation rate without providing ventilation holes on roll paper or forming paper and using a hardness improving agent, and a cigarette with the cigarette filter.

The present invention provides in 1 st aspect thereof a cigarette filter comprising a filter plug including a cylindrical body formed by rolling a plug wrap, and a filter material provided in the cylindrical body, wherein the wrap is formed of a high-rigidity high-permeability paper having a longitudinal rigidity of 30 or more and a permeability of 1000CORESTA units or more as measured in accordance with JIS P8143.

The 2 nd aspect of the present invention provides a cigarette filter comprising a plurality of filter rods each including a tubular body formed by rolling a filter plug wrap into a tubular shape and a filter medium provided in the tubular body, and including an upstream-most filter plug and a downstream-most filter plug, and a plug wrap wrapping the outer peripheries of the plurality of filter rods and connecting the plurality of filter rods, wherein the wrap of at least 1 filter rod out of the plurality of filter rods is made of a high-rigidity high-permeability paper having a longitudinal rigidity of 30 or more and a permeability of 1000CORESTA units or more as measured in accordance with JIS P8143.

The 3 rd aspect of the present invention provides a cigarette filter comprising a plurality of filter rods each comprising a tubular body wound in a tubular shape from a plug wrap and a filter medium provided in the tubular body, and including an upstream-most filter rod and a downstream-most filter rod, and a plug wrap wrapping the outer peripheries of the filter rods and connecting the filter rods, wherein the plug wrap is made of a high-rigidity high-permeability paper having a longitudinal rigidity of 30 or more and a permeability of 1000CORESTA units or more as measured in accordance with JIS P8143.

In addition, according to the 4 th aspect of the present invention, there is provided a filter-tipped cigarette comprising a cigarette body and a cigarette filter provided at one end of the cigarette body, wherein the cigarette body comprises a cigarette rod wrapped with a wrapping paper, and the filter-tipped cigarette comprises the cigarette filter of the present invention.

Drawings

Fig. 1 is a schematic perspective view partially developed showing a cigarette with a cigarette filter according to an embodiment of the present invention, wherein the cigarette has a single filter.

Fig. 2 is a schematic perspective view partially developed showing a cigarette with a cigarette filter according to an embodiment of the present invention, wherein the cigarette has a multi-segment filter.

Figure 3 is a diagrammatic perspective view, partially expanded, showing a cigarette with a cigarette filter according to an embodiment of the present invention, wherein the cigarette has a fluted single segment filter.

Fig. 4 is a graph showing the hardness of a cellulose acetate filter rod according to an embodiment of the present invention and the hardness of a conventional cellulose acetate filter rod at the same time.

Fig. 5 is a graph showing the hardness of a cellulose acetate filter rod according to an embodiment of the present invention and the hardness of a conventional cellulose acetate filter rod at the same time when the amount of triacetin added is changed.

Fig. 6 is a graph showing the hardness of a paper filter plug (paper filter plug) according to an embodiment of the present invention and the hardness of a conventional paper filter plug at the same time.

Fig. 7 is a graph showing the change with time in the proportion of menthol in the cellulose acetate filter in the tobacco shred and the filter material.

Fig. 8 is a graph showing a change with time in the proportion of menthol present in the tobacco shred and the filter material in the paper filter (paper filter).

Fig. 9 is a graph showing the temporal change in the amount of menthol released in the mainstream smoke of a cigarette with a cellulose acetate filter and a cigarette with a paper filter.

Detailed Description

The cigarette filter of the present invention comprises: a so-called single filter composed of a single filter rod, and a so-called multi-filter including a plurality of filter rods including an upstream-most filter rod and a downstream-most filter rod. In any of the filters, each of the filter rods includes a generally cylindrical tube body wound in a cylindrical shape from a roll paper, and a filter material provided in the tube body. In other words, the filter plug includes a filter material wound (wrapped) with a wrapping paper. In the multi-filter, a plurality of filter rods are wrapped with a plug wrap to be connected to each other. Note that, in the present invention, the terms "upstream" and "downstream" are based on the flow direction of the cigarette mainstream smoke flowing through the cigarette.

In the present invention, the wrapping paper of the individual filter is made of a specified high-rigidity high-permeability paper. In the present invention, the wrapping paper and/or plug wrap of at least one filter plug in the multi-tipping filter is made of a specified high-rigidity high-permeability paper.

The high-rigidity and high-air-permeability paper used in the present invention has a longitudinal rigidity (rigidity in the longitudinal direction) of 30 or more as measured according to JIS P8143 (rigidity test method by the self-weight bending method of paper), and an air permeability of 1000CORESTA units or more. The high-rigidity high-air-permeability paper preferably has a longitudinal rigidity of 30-400 and an air permeability of 1000-30000 CORESTA units (CORESTA, International tobacco science and cooperative research center).

Examples of the high-rigidity and high-air-permeability paper used in the present invention (indicated by symbols S1 to S4) are shown in table 1. Also shown in Table 1 is a porous high-permeability filter plug wrap (regular wrap; denoted by the symbol P) which has been conventionally used.

[ Table 1]

Description is made of the case of using cellulose acetate fiber tow (セルコ - スアセテ - ト sustain トウ) as a filter material: as described above, in order to impart a predetermined hardness to a filter, a conventional method is to add a plasticizer such as triacetin to the filter in an amount of 5 to 10 wt% based on the weight of cellulose acetate fiber. However, by using the high-rigidity high-permeability paper of the present invention, even in the case where a plasticizer is added in an amount of less than 5% (including 0%) by weight of the cellulose acetate fiber, the same level of filter hardness as that of the conventional method can be exhibited. Of course, if the same amount of plasticizer as that of the conventional method, which is 5 to 10 wt% based on the weight of the cellulose acetate fiber, is added to the cellulose acetate fiber, the hardness of the fiber can be increased over the conventional hardness of the filter.

However, it has been found from the findings so far that the addition of triacetin in an amount exceeding 12% by weight causes a problem of an acetic acid odor caused by the dissolution of cellulose acetate fibers and the decomposition of triacetin. Therefore, as the hardness of the conventional filter obtained without these problems, the upper limit value thereof is equivalent to the hardness when 12 wt% of triacetin is added. However, by using the high-rigidity and high-permeability paper of the present invention, when 12% by weight of triacetin is added, the hardness can be increased to a level exceeding the upper limit. That is, the present invention can also be applied to a cellulose acetate filter to which triacetin is added in an amount of more than 10% by weight and 12% by weight or less.

The filter material of the cigarette filter of the present invention is not limited to cellulose acetate fibers. In the present invention, the following filter materials may also be used: a filter (paper filter) obtained by forming a filter or a paper filter (subjected to a crimping treatment) with a nonwoven fabric, which does not use, for example, a hardness-improving agent (additive for improving the hardness of the filter at the end), a curing agent such as a plasticizer such as triacetin, or a binder (for example, polyvinyl alcohol, polyvinyl acetate, polyethylene glycol, dimethyl phthalate, diethyl phthalate, or the like) added for bonding a filter material.

Conventionally, it has been difficult for a filter medium not using a hardness-improving agent to exhibit a filter hardness equivalent to that of a cellulose acetate filter to which triacetin has been added. However, by using the high-rigidity and high-permeability paper of the present invention, the filter hardness can be exhibited at a level equal to or higher than that of a cellulose acetate filter to which triacetin is added.

In the case of a filter using a filter material without using a hardness-improving agent, when such a filter is used in a cigarette with a filter, which has a flavor (for example, menthol, limonene, peppermint oil (peppermint oil), spearmint oil (spearmint oil), ethyl acetate, ethyl butyrate, ethyl benzoate, and other esters, linalool, nerol, geraniol (グラニオ - ル), and other phenols, such as anethole, aldehydes such as cinnamaldehyde and vanillin, lactones, and pyrazines) adsorbed together with triacetin to cellulose acetate fibers, such as menthol, additional advantages are exhibited.

For example, in a conventional menthol cigarette, menthol is mixed in tobacco shreds, and a cellulose acetate filter using triacetin is attached. However, in the current cellulose acetate filter, menthol in the cigarette is adsorbed in the cellulose acetate fiber together with triacetin with time. Menthol adsorbed in cellulose acetate fibers does not migrate into mainstream smoke upon smoking. Thus, even if menthol is present in the cigarette, the amount of menthol released in the mainstream smoke decreases with time while menthol is adsorbed in the filter. In contrast, unlike cellulose acetate filters using a plasticizer, filter materials such as paper filters, which do not use a plasticizer, a curing agent, and a binder, menthol is not adsorbed in the filter over time but remains in the tobacco shreds. Thus, even if the amount of menthol in the cigarette is equal, the amount of menthol released from the tobacco shreds during smoking increases, and the amount of menthol released during use increases compared to a cellulose acetate filter containing triacetin. Further, since the adsorption of menthol into the filter does not occur, the amount of menthol released in the mainstream smoke during smoking can be made stable over time. The same effect can be obtained also in the case where a flavor such as menthol is added to the filter body or in the case where the flavor is added to the aluminum laminated paper in the cigarette case. In addition, even in the case of using cellulose acetate fibers, the above-described effects can be exhibited by reducing the amount of triacetin added, which causes adsorption, or using a substance that is less likely to adsorb than triacetin (e.g., polyvinyl alcohol, polyvinyl acetate, polyethylene glycol, epoxy resin, etc.) as a hardness improver.

Of course, in the multi-segment filter, a filter plug using a filter material not using the hardness improver and a filter plug using cellulose acetate fibers may be used in combination.

Further, the filter of the present invention may further include a filter plug to which activated carbon particles (activated carbon) are added. In the case of a single filter rod, activated carbon particles may be incorporated into a single filter rod. In the case of a multi-segment filter, activated carbon particles are usually added to a filter plug located on the upstream side of the filter plug on the most downstream side.

The filter of the present invention may be constructed as a recess filter as described in the pamphlet of International publication No. 00/00047 or Japanese patent application laid-open No. 2004-516814. That is, in this case, in the single filter, the cylindrical body of the single filter plug projects from the downstream end face of the filter medium to form the recess portion. In the multi-segment filter, the plug wrap extends from the downstream end surface of the filter plug on the most downstream side to form a recess portion.

The present invention will be described below with reference to the accompanying drawings. Throughout the drawings, identical elements are labeled with the same reference numerals.

Figure 1 is a diagrammatic perspective view, partially expanded, showing a cigarette 100 with a cigarette filter having a single filter.

The filter-tipped cigarette 100 includes a cigarette body 110, and a filter plug 120 provided at one end of the cigarette body 110. The cigarette body 110 includes a cigarette rod (not shown) and a wrapping paper for wrapping the outer periphery of the cigarette rod, as in a general cigarette. The cigarette rod is made of cigarette filler such as tobacco shred. The filter plug 120 includes a cylindrical body 122 wound in a cylindrical shape from the wrapping paper 121, and a filter material 123 provided in the cylindrical body 122. The cigarette body 110 and plug 120 are joined to one another by tipping paper 130 to effect the end-face engagement as in a conventional filter cigarette. A ventilation hole 131 may be provided through the tipping paper 130.

In the filter-tipped cigarette shown in fig. 1, the high-rigidity and high-permeability paper of the present invention is used as the wrapping paper 121.

Figure 2 is a diagrammatic perspective view, partially expanded, showing a cigarette 200 with a cigarette filter having 2 filters as one of the multi-segment filters.

At one end of the cigarette body 110 of the cigarette 200 with a cigarette filter, 2 filters 210 are provided. The 2 segment filter 210 has 2 filter rods 220 and 230. The upstream filter plug 220 includes a cylindrical body 222 wound in a cylindrical shape from the wrapping paper 221, and a filter material 223 provided in the cylindrical body 222. Similarly, the downstream filter plug 230 includes a cylindrical body 232 wound in a cylindrical shape from the wrapping paper 231, and a filter material 233 provided in the cylindrical body 232. The 2 filter rods 220 and 230 are joined to one another by a plug wrap 240 to effect splicing between the end faces. Also, the 2 filters 210 are joined to one another by tipping paper 130 to effect the end-face engagement as in a conventional filter cigarette.

In the filter-tipped cigarette shown in fig. 2, one or both of the wrapping papers 221 and 231 may be formed of the high-rigidity high-permeability paper of the present invention.

Since the downstream filter rod 230 is normally placed in the mouth, most smokers use the lips to identify filter firmness. As described above, if the high-rigidity high-permeability paper of the present invention is used for the wrapping paper 231 of the downstream filter plug 230, the smoker can feel that the filter hardness is maintained or improved without using the high-rigidity high-permeability paper for the wrapping paper of another filter plug. In addition, during smoking, the smoker holds the cigarette with his fingers. At this time, the hardness of the filter may be sensed by fingers. In such a case, it is desirable to use the high-rigidity and high-air-permeability paper of the present invention in the wrapping paper 221 of the filter plug 220 on the upstream side of the tobacco shred. Of course, if the high-rigidity and high-air-permeability paper of the present invention is used for both the roll papers 221 and 231, the filter hardness can be recognized by both the lips and the fingers. In addition, in the cigarette using the multi-filter, in order to maintain and improve the filter hardness of the entire filter, the high-rigidity high-permeability paper of the present invention is used for the filter plug paper 240 of the multi-filter, so that the hardness of the entire filter can be maintained and improved. In this case, the roll paper 221 and 231 may be conventional roll paper (rigidity: 10-15; air permeability: 70-30000 CORESTA unit; thickness: 30-80 μm; basis weight: 15-27 g/m)²). In addition, in order to further increase the filter hardness, the filter hardness can be further increased by using a high-rigidity high-permeability paper for the wrapping paper 221 and/or 231 and simultaneously using the high-rigidity high-permeability paper of the present invention for the plug paper 240, because a double-layer high-rigidity high-permeability paper is used.

Figure 3 is a diagrammatic perspective view, partially exploded, showing a cigarette 300 with a cigarette filter having a fluted single segment filter.

The recess filter cigarette 300 includes a cigarette body 110 and a filter plug 320 provided at one end of the cigarette body 110. The filter plug 320 includes a cylindrical body 322 wound in a cylindrical shape from a wrapping paper 321, and a filter material 323 provided in the cylindrical body 322. The cylindrical body 122 further protrudes from the downstream end surface of the filter material 323 to form a groove portion 324. The cigarette body 110 and plug 320 are joined to one another by tipping paper 130 to effect the end-face join, as in a conventional filter cigarette. A ventilation hole 131 may be provided through the tipping paper 130.

In the filter-tipped cigarette shown in fig. 3, the high-rigidity and high-permeability paper of the present invention is used as the wrapping paper 321.

Examples

The present invention will be described with reference to examples.

Example 1

Using the paper shown in table 1 above as a filter plug wrap, a filter plug was produced by a conventional method. The filter material used was a conventional cellulose acetate fiber tow with the addition of triacetin in an amount corresponding to 6% by weight of the cellulose acetate fiber tow. The circumference is 24.5mm in terms of the diameter of the filter rod and 25mm long. The roll paper covers the outer periphery of the filter material appropriately. And the hardness of the resulting filter was measured.

The hardness of the filter should be originally measured in a state where the filter is attached to a cigarette. However, due to the problem of the measuring instrument, it is difficult to measure the hardness of the filter in a state where the filter is attached to the cigarette. Therefore, the filter hardness was measured in a filter rod state before the filter was attached to the cigarette (hereinafter, the same measurement method was used for the filter hardness).

For the measurement of the filter hardness, NFQA (Filter quality measuring apparatus) manufactured by JTTohsi, Inc. was used. The results are shown in FIG. 4. The filter hardness is calculated from the deformation of the filter that occurs when a certain constant load is applied. Thus, the smaller the deformation, the harder the filter. That is, the smaller the value of the filter hardness in fig. 4, the harder the filter.

As is clear from fig. 4, the filter hardness of the filter rods using the high-rigidity and high-air-permeability paper (S1 to S4) of the present invention was improved as compared with the filter rods using the conventional wrapping paper P. The filter rods using the high-rigidity and high-air-permeability paper (S1 to S4) of the present invention each have an air permeability of 1000CORESTA units or more. Further, high-rigidity roll paper having air permeability equivalent to that of currently-used roll paper P can also be realized (S4).

Therefore, by using the high-rigidity high-air-permeability paper of the present invention, not only can the hardness of the filter be maintained and improved, but also the following problems can be avoided: the problem of providing ventilation holes in the prior art, namely the problem of increasing the cost when manufacturing cigarettes; low versatility in various smoking articles such as low tar; the stability in terms of quality is insufficient.

Example 2

Filter rods of the same size as in example 1 were produced using the conventional wrapping paper P and the high-rigidity and high-air-permeability paper S4 shown in table 1, respectively. The filter material was the same as that in example 1, and a conventional cellulose acetate fiber tow was used, but the amount of triacetin added to the tow (an amount corresponding to 0 to 12% by weight of the cellulose acetate fiber) was changed. The hardness of the obtained filter rods was measured in the same manner as in example 1. The results are shown in FIG. 5. In fig. 5, a line a represents the result when the roll paper P is used; line b represents the result when high stiffness high air permeability paper S4 was used.

As is clear from fig. 5, at any triacetin addition amount, the filter hardness was improved by using the high-rigidity and high-permeability paper S4 as compared with the filter plug using the conventional plug wrap P.

As described above, in the conventional cigarette, the amount of triacetin added to the filter accounts for 5 to 10% by weight based on the weight of the filter material. However, it is known that when the high stiffness and high air permeability paper S4 is used, the filter hardness can be increased without increasing the amount of triacetin.

In the case where the amount of triacetin is small, it is known that if the high-rigidity high-permeability paper S4 is used, the filter hardness when the regular wrapper paper P is used and the amount of triacetin is about 6 wt% can be exhibited when the amount of triacetin is about 3 wt%. Therefore, by using the high-rigidity and high-air-permeability paper S4, the hardness equivalent to that of the conventional filter can be obtained even when the amount of triacetin is small.

Example 3

So-called paper filter plugs were produced using the papers shown in table 1. As the filter material, creped pulp paper (pulp paper) was used. The shape of the obtained filter plug was the same as in example 1. Ventilation resistance (ventilation resistance) of each filter stick is 350mmH₂O/120 mm. The hardness of the obtained filter rods was measured in the same manner as in example 1. The results are shown in FIG. 6.

As is clear from fig. 6, the hardness of the filter plug of paper using the high-rigidity and high-permeability paper of the present invention was sufficiently improved, as in the case of the filter plug of cellulose acetate wrapped with the high-rigidity and high-permeability paper of the present invention shown in example 1. Further, according to the present invention, the hardness of the cellulose acetate filter can be increased to a level equivalent to the hardness of the filter when 6 wt% triacetin is added.

Example 4

A filter-tipped cigarette was produced by attaching a cellulose acetate filter plug produced using the normal plug wrap P in example 1 and a filter plug produced using the high-rigidity and high-permeability paper S4 in example 3 to a cigarette body using tipping paper. Menthol was added to tobacco shreds of cigarettes (3.0 mg of menthol was added to 1 cigarette). After the production, the filter-tipped cigarettes were stored at 22 ℃ and 60% relative humidity for 12 weeks. The proportion of menthol present in the cut tobacco and the filter material during the storage period was measured by the method shown below. The results are shown in FIGS. 7 and 8. Figure 7 represents the results of a cellulose acetate filter rod measurement; fig. 8 represents the measurement results of the paper filter plug. In fig. 7 and 8, the hatched portions represent the proportion of menthol in the filter material, and the hollow portions represent the proportion of menthol in the tobacco shred.

The amount of menthol released (menthol/tar ratio (M/T ratio)) in the mainstream smoke of the two types of filter cigarettes during the storage period was measured by the following method. The results are shown in FIG. 9. In fig. 9, line a represents the measurement results of the cigarette with a paper filter; line b represents the measurement of the cigarette with the cellulose acetate filter.

< method for measuring menthol amount in tobacco shred and Filter Material >

The cigarette is divided into a tobacco shred part (including roll paper) and a filter part.

Subsequently, the cut tobacco portion was shaken in methanol at room temperature for 40 minutes, and then left to stand for 24 hours. Then, after shaking was performed again for 40 minutes, the supernatant was taken and used as a menthol extract.

On the other hand, after shaking the filter cartridge in methanol at room temperature for 40 minutes, it was left for 24 hours, and then, the supernatant was taken out and used as a menthol extract.

Each of the menthol extracts obtained above was analyzed by a gas chromatograph equipped with a hydrogen Flame Ionization Detector (FID) as a detector. And menthol was quantified by the internal standard method. As internal standard, 1, 3-butanediol was used.

< method for measuring menthol/tar ratio >

The tar content in cigarette mainstream smoke was measured according to ISO 3308 and 4387.

For menthol in cigarette mainstream smoke, after mainstream smoke was captured into Cambridge filters (Cambridge filters) according to ISO 4387, the Cambridge filters were shaken in methanol at room temperature for 40 minutes, and then the supernatant was taken as a menthol extract. The menthol extract obtained above was analyzed by a gas chromatograph equipped with FID as a detector. In addition, menthol was quantified by the internal standard method. As internal standard, 1, 3-butanediol was used.

The menthol/tar ratio (M/T ratio) was determined from the values of the amount of tar and the amount of menthol in the mainstream smoke measured by the above method.

From the above results, it was found that, when a cellulose acetate filter was used, menthol was transferred from the tobacco shred portion to the filter element portion. As a result, the amount of menthol released decreases with time. On the other hand, when a paper filter is used, menthol is not transferred to the filter but remains in the tobacco shreds. Thus, the menthol release amount is more stable over time than in the case of using a cellulose acetate filter, and a high menthol release amount can be achieved.

As described above, according to the present invention, even when paper without using a hardness-improving agent is used as a filter material, a menthol cigarette having a high M/T ratio, i.e., a high menthol emission amount, while ensuring filter hardness can be obtained.

Claims (17)

1. A cigarette filter comprising a filter plug comprising a cylindrical body formed by rolling a plug wrap and a filter material provided in the cylindrical body, wherein the wrap is formed of a high-rigidity high-permeability paper having a longitudinal rigidity of 30 or more and a permeability of 1000CORESTA units or more as measured in accordance with JIS P8143.

2. A cigarette filter according to claim 1 wherein said filter rod contains activated carbon particles therein.

3. A cigarette filter comprising a plurality of filter rods each comprising a tubular body formed by rolling a filter plug wrap around a tubular body and a filter medium provided in the tubular body, and a plug wrap connecting the plurality of filter rods, wherein the filter rods comprise a filter plug on the most upstream side and a filter plug on the most downstream side, wherein the wrap of at least 1 of the filter rods is made of a high-rigidity high-permeability paper having a longitudinal rigidity of 30 or more and a permeability of 1000CORESTA units or more as measured in accordance with JIS P8143.

4. A cigarette filter as in claim 3 wherein the plug wrap is comprised of the high stiffness high air permeability paper.

5. A cigarette filter comprising a plurality of filter rods and a plug wrap which wraps the outer peripheries of the filter rods and connects the filter rods, wherein each of the filter rods comprises a tubular body wound in a tubular shape from a plug wrap and a filter medium provided in the tubular body, and the filter rods include a most upstream filter rod and a most downstream filter rod, wherein the plug wrap is made of a high-rigidity high-permeability paper having a longitudinal rigidity of 30 or more and a permeability of 1000CORESTA units or more as measured in accordance with JIS P8143.

6. A cigarette filter according to claim 3, wherein activated carbon particles are contained in a filter plug located on an upstream side of said most downstream side filter plug.

7. A cigarette filter as in claim 1 wherein the high stiffness, high air permeability paper has a longitudinal stiffness of 30 to 400 and an air permeability of 1000 to 30000CORESTA units.

8. A cigarette filter according to claim 1, wherein the filter material in the filter plug of the high-rigidity high-permeability paper comprises cellulose acetate fiber tow and a plasticizer is mixed in a proportion of 0% or more and less than 5% by weight of the fiber tow.

9. A cigarette filter according to claim 1, wherein the filter material in the filter plug comprising the high-rigidity high-permeability paper comprises cellulose acetate fiber tow and a plasticizer is mixed in a proportion of 5 to 10% by weight of the fiber tow.

10. A cigarette filter according to claim 1, wherein the filter material of the plug of the high-rigidity high-permeability paper contains cellulose acetate fiber tow and a plasticizer is mixed in a proportion of 10% by weight or more and 12% by weight or less of the fiber tow.

11. The cigarette filter of claim 1, wherein the filter material does not include a hardness enhancer therein.

12. A cigarette filter as in claim 11 wherein the filter material comprises paper.

13. The cigarette filter of claim 1, comprising a flavorant.

14. The cigarette filter of claim 13, wherein the flavorant comprises menthol.

15. A cigarette filter as in claim 1 wherein the barrel projects from a downstream end face of the filter material to form a groove portion.

16. A cigarette filter according to claim 3, wherein said plug wrap extends from a downstream end surface of said most downstream filter plug to form a recessed portion.

17. A filter-tipped cigarette comprising a cigarette body including a cigarette rod wrapped with a wrapping paper, and a cigarette filter provided at one end of the cigarette body, the cigarette filter being constituted by the cigarette filter according to claim 1.