KR20100101686A - Smoking article - Google Patents

Abstract

Smoking article 10 has a filter 20 positioned at one end, the filter having a first section 34, a second section 41, and a third section 51 that are continuously disposed along the cylindrical axis of the smoking article. ). Each first section 31 and third section 51 comprise one or more tubes 35, 55 spanning the length of each section substantially parallel to the cylindrical axis of the smoking article. The second section 41 comprises a material of substantially higher filtration efficiency than the tubes 35, 55 of the first and third sections. Ventilation holes 43 may be provided around the circumference of the filter in one or more zones.

Description

Smoking article {SMOKING ARTICLE}

The present invention relates to smoking articles such as cigarettes, in particular smoking articles comprising filters.

As cigarettes are smoked, tar is generated when the tobacco in the cigarette is burned. In recent years, consumer preference has been changed to low tar tobacco. Therefore, it is desirable to produce tobacco that delivers less tar to the user.

Current cigarettes contain filters that can help reduce tar output for many years. When the cigarette is smoked, the combustion point moves closer to the filter. If the cigarette first catches fire, the rods of the unburned tobacco itself provide a certain amount of filtration, thus helping to reduce tar transmission. However, this action is lost as the tobacco rod burns to shorter and shorter lengths, resulting in increased smoke delivery for equivalent puff volumes during equivalent puffs. It is also desirable to produce tobacco that delivers less tar to equivalent puffy consumers.

It is known to provide hollow tubes along the central axis of a portion of the filter. For example, GB 2177890 discloses a cigarette in which the filter comprises first and second elements, the first element being adjacent to the tobacco rod and the second element being adjacent to the mouth. The first element incorporates a thin center tube of heat shrinkable material surrounded by cellulose acetate. When tobacco is initially smoked, the tube provides a low resistance path for smoking through the first element (prior to smoke that must pass through the surrounding cellulose acetate). This low resistance path through the first element helps to compensate for the higher initial resistance of the long tobacco load. However, when the cigarette warms up, the central tube collapses, and the empty space is then filled by the expansion of the surrounding cellulose acetate material. The tube now does not provide a low resistance path through the first element, instead the smoke must pass through the relatively high resistance of the cellulose acetate of the first element.

A somewhat similar configuration is disclosed in EP 481596. In this document, however, the tube is not collapsed by heat. Rather, the tube is gradually blocked by smoke components that collect on the filter material at the end of the tube, so that the smoke must flow through the more resistant material around the filter. This tube may have holes along its length to cause a more gradual change.

In conventional cigarettes, the filtration characteristics of the filter are sufficiently independent of the amount of smoke provided to the filter, although there is a well known relationship between filtration efficiency and flow. As a result, the performance of such a filter, for example with respect to tar transfer, is likely to change with different puff volumes and different puff profiles.

The present invention provides a smoking article such as a cigarette having a filter located at one end. The filter comprises at least a first section, a second section and a third section disposed continuously along the cylindrical axis of the smoking article. Each first section and third section include one or more tubes running over the length of each said section. The second section comprises a filter material of substantially higher filtration efficiency than the tubes of the first and third sections.

Such a filter may help to provide a more consistent level of tar, with a reduced dependence on the smoking regime or how many smoking articles have already been consumed. For example, in one embodiment the outlet of the tube of the first section is at least partially blocked after the first smoking amount. As a result, more smoke now exits the remainder of the first filter section (not the tube) which contains some form of filter material. After the additional amount of smoking, the inlet to the tube in the third section is at least partially blocked. More smoke is now passed through the rest of the third filter section (not the tube), which again contains some form of filter material. Thus, this embodiment provides a gradual and controlled increase in the filtration efficiency of the filter when the smoking article is consumed. Note that an increase in filtration efficiency occurs more quickly for higher puff volumes and / or puff speeds (in this case the tube shuts off faster). In addition, an increase in the filtration efficiency of the filter helps to compensate for the reduced filtration by the tobacco rod itself, which is not burned when the smoking article is consumed.

In one embodiment, the tube (s) of the first section is coaxial with the tube (s) of the third section. The tubes of the first section and / or the third section may be located centrally (ie, coaxial with the smoking article) within the smoking article, or may be provided as groove (s) in the outer circumference of the filter. Another possibility is that the tube is located in the middle of the outside and center of the filter. The number and positioning of the tubes can vary as required to control the overall filter characteristics, and can vary from one filter section to another.

In one embodiment, the tube (s) of the first section and / or the third section have a diameter in the range of 0.1 to 3 mm, more specifically 0.5 to 1.5 mm and a length in the range of 4 to 15 mm. This tube dimension helps to determine the overall properties of the filter. For example, this dimension is longer for the tube, in particular for the end of the tube, where the larger diameter is blocked (at least partially) during smoking. Thus, the tube dimensions can be adjusted according to the desired properties of the filter or smoking article. Different tubes may have different dimensions (both for tubes of different filter sections and also for multiple tubes of a single filter section).

In one embodiment, these tubes are hollow and the first filter section, the second filter section and the third filter section all comprise filter material, such as cellulose acetate, paper, etc. (different filter sections may comprise different filter materials. Can be). For the first filter section and the third filter section, the filter material surrounds or is embedded in the tube (s) of these sections. The relative filtration efficiency of the filter material of the different sections can be used to control the overall properties of the filter. For example, in one embodiment the filter material of the first filter section has a lower filtration efficiency than the filter material of the second and third filter sections. As a result, the increase in filtration efficiency when the tube passing through the first filter section is at least partially blocked is less than the increase in filtration efficiency when the tube passing through the third filter section is at least partially blocked.

Ventilation may be provided in one or more zones around the circumference of the filter. The ventilation zone is preferably located downstream of the potential blocking point. In one embodiment, vents are provided outside the second filter section and / or the third filter section. If the tube passing through the first filter section and the third filter section is located centrally (ie coaxial with the smoking article), initially most of the airflow follows the central axis of the smoking article. However, when the ends of the tube are at least partially blocked and the flow of smoke is forced towards the outer portion of the smoking article, this increases the amount of air drawn through the vent to weaken the smoke. In addition, the pressure difference or pressure drop PD of the smoking article will increase. The ventilation location immediately downstream of the blocking point results in increased ventilation levels as the pressure drop (PD) of the filter increases.

In one embodiment, the filter comprises additional section pairs continuously along the cylindrical axis of the smoking article after the third section. Each additional section pair includes a first additional section and a second additional section. The first additional section includes one or more tubes spanning the length of the first additional section substantially parallel to the cylindrical axis of the smoking article. The second additional section comprises a filter material of substantially higher filtration efficiency than the tube of the first additional section. Increasing the number of filter sections accordingly allows further control over the filter action. For example, if the fourth and fifth filter sections are provided similarly to the second and third filter sections, the tubes in the fourth filter section are at least partially blocked briefly after the tubes in the third filter section are at least partially blocked. Will be. Therefore, such a filter has a step change in increasing filter efficiency as each tube is blocked.

The present invention also provides a filter for use in any smoking article as described above.

Various embodiments of the present invention will be described in detail only by way of example with reference to the following drawings.

1 illustrates a cigarette filter according to an embodiment of the present invention,
2 illustrates the action of the tobacco filter of FIG. 1 on an initial puff according to one embodiment of the invention,
3 illustrates the action of the tobacco filter of FIG. 1 on a second stage puff according to an embodiment of the invention,
4 illustrates the action of the tobacco filter of FIG. 1 on a third stage puff according to one embodiment of the invention.

1 is a schematic diagram of a cigarette 10 according to an embodiment of the present invention. Cigarette 10 generally has a cylindrical shape and includes a tobacco rod 15 (only partially shown in FIG. 1) which is connected to filter 20 using an outer wrap 21. This filter is located at the mouth end 100 of the cigarette. The cigarette 10 is lit at the end of the tobacco rod 15 opposite the mouth end.

The filter 20 comprises three sections 31, 41, 51 arranged along the cylindrical axis of the cigarette, each of which is cylindrical in shape. The section 31 is adjacent to the tobacco rod 15, the section 51 is adjacent to the mouth end 100, and the section 41 is between the sections 31 and 51. Thus, the shape of the cigarette 10 is determined by three consecutive planes, all of which are perpendicular to the cylindrical axis of the cigarette. The first plane forms a boundary between the tobacco rod 15 and the first filter element 31, the second plane forms a boundary between the first filter element 31 and the second filter element 41, The third plane forms a boundary between the second filter element 41 and the third filter element 51. In one embodiment, the spacing between different planes (and therefore the length of each filter section) is within the range of 5 to 10 mm. (In other embodiments, this spacing may be in the range of 4 to 15 mm.)

The first filter section 31 comprises a tube 35 and the third filter section 51 also comprises a tube 55. The tubes 35, 55 are both coaxial with the cylindrical axis of the tobacco, and each tube 35, 55 extends over the length of its respective section. The radius of the tubes 35, 55 is considerably smaller than the radius of the cigarette. For example, the diameter of the tube may be only about 0.1 to 3 mm. In one embodiment, the tubes 35 and 55 each have a diameter of approximately 0.5-1 mm. Note that when the radius of the tube as a whole is 20% of the radius of the cigarette, the cross sectional area of the tube is only 4% of the cross sectional area of the cigarette.

The tubes 35 and 55 may be paper, cardboard, plastic or any other suitable material and may have a porous surface or a non-breathable surface. In the illustrated embodiment, the tubes 35 and 55 are hollow, but in other embodiments may have a filler that provides very little resistance to airflow. In the illustrated embodiment, the tubes 35 and 55 are substantially identical to one another, but in other embodiments may be different from each other where appropriate in terms of dimensions, shapes and / or other properties.

In the first section 31, the tube 35 is surrounded by filter material 32, such as cellulose acetate, paper, polypropylene, or any other suitable material. This material is formed to have a relatively low density and therefore a relatively low (but considerably higher than hollow tube) filtration efficiency. The intermediate section 41, which does not include a center tube, also includes a filter material 42, such as cellulose acetate, paper, polypropylene, or the like. This material is formed to have a relatively high density, thus having a high filtration efficiency (relative to the filtration efficiency of the material 32). In the third section 51, the tube 55 is also surrounded by filter material 52 such as cellulose acetate, paper, polypropylene, and the like. In addition, this material is formed to have a relatively high density, thus having a high filtration efficiency (relative to the filtration efficiency of the material 32).

The outer sheath 21 has two circumferential rings of ventilation holes. The first ring of vent hole 43 is provided around the second section of filter 41, while the second ring of vent hole 53 is adjacent to the starting point of the third section of filter 51 (ie the mouth side). Away from the end 100). These vents allow air to be sucked into the tobacco filter and thus weaken the smoke passing through it.

FIG. 2 shows the main smoke flowing through the cigarette 10 of FIG. 1 when the cigarette is first smoked in accordance with one embodiment of the present invention. Smoke from the burning tobacco moves from the tobacco rod 15 to the filter 20. The smoke now passes through the tube 35 of the first element 31 prior to passing through the filter material 32 because the tube 35 provides a low resistance to the smoke flow. The smoke then passes through the high filtration efficiency material of the second section 41 before exiting the mouth end 100 of the filter via the third section 51. In the third filter section 51, the smoke passes through the tube 55 in preference to the surrounding filter material 52 due to the low flow resistance of the tube 55.

In this step, it is the second section 41 of the filter 20 that provides filtration of the majority of the filter 20. This filtration action is supplemented by the passage of smoke through the relatively long portion of the tobacco rod 15 that has not been burned before reaching the filter 20. Relatively little ventilation air is aspirated through the vents 43 and 53 because the main flow of smoke through the cigarette is close to the central axis of the cigarette 10-ie far from the outer surface where the vent is located. This is because there is a low filter pressure drop upstream.

In the form of FIG. 2, the smoke moves at a relatively high velocity through the tube 35 due to the low flow resistance, after which the filter material 42 enters the second section 41 which provides a much higher flow resistance. When slow down. This deceleration results in the concentration of smoke at the contact point 36-ie the dense filter material 42 of the second element 41 is adjacent to the outlet from the tube 35. Elevated concentrations at the close point 36 cause tar, which acts to gradually block the exit from the tube 35, to settle on the filter material 42.

This causes the tube 35 to be in the state shown in FIG. 3 where it is blocked by precipitation of the material at the contact point 36. (As used herein, "blocked" means partial or complete blocking.) Thus, more smoke passing through the first filter section 31 is now the outer ring of the first filter section 31. It moves out of the tube 35 through the main body of filter material 32 which occupies an outer annulus. This provides increasing filtration for the smoke moving through the first filter section 31 (compared to when the smoke passed through the tube 35 instead of the filter material 32).

After passing through the filter material 32 of the first filter element 31, the smoke is drawn through the second element 41 and collects at the inlet 56 into the tube 55. The smoke flow then passes through the tube 55 as described above to exit the filter 20 at the mouth end 100.

The smoke flow through the second filter element 41 now proceeds somewhat closer to the vent 43 on the outside of the filter 20 (compared to the form of FIG. 2). This is because, due to the (completely or partially) blocked center tube 35, more smoke exits the first filter section 31 closer to the outside of the cigarette. The restriction of the end of the tube 35 increases the amount of ventilation air entering the filter by increasing the pressure drop in the filter section upstream of the vent. Also, adjacent to the incoming ventilation air, the more smoke passes through the radially outer portion of the filter, the more smoke is deflected radially inside by the ventilation air across the filter material towards the center portion of the filter, thereby filtering Provide an increase in efficiency.

The concentration of smoke towards the area 56 of the second filter adjacent to the inlet to the tube 55 causes the density of the smoke to increase at this close point. This increase in smoke concentration in turn causes smoke material, such as tar, to settle in the filter material. Thus, the more cigarettes are smoked, the more tar there is in location 56, which limits the escape of smoke from filter 20 through tube 55 by gradually blocking the inlet of tube 55.

This leads to the state shown in FIG. In the third filter section 51, with the smoke flow through the center tube 55 now restricted, more smoke passes through the filter material 52 surrounding the center tube-ie the third filter section 51. Pass through the outer ring). Thus, the smoke is subjected to high filtration efficiency of the filter material 52. This helps to compensate for the reduced filtration in the tobacco rod 15 (substantially shorter in length than when the cigarette was first lit).

In the form of FIG. 4, the flow through the second filter section 41 is mostly parallel to the cylindrical axis of the cigarette and is generally located at the (radial) outer part of the filter closer to the vent holes 43, 53. This increased flow adjacent to the filtration holes 43, 53 combines with the overall increase in the pressure drop of the filter due to the (partial) blockage of the inlet of the tube 55, attracting increased ventilation air to the mouth. The smoke reaching the end 100 is weakened more.

The more intensely puffed the cigarette, the more tar is generated and the faster the smoke exits the tube 35, the higher the impact filtration in FIG. Also, for each gradual step, as smoke is drawn towards the outer portion of the filter 20 and therefore closer to the vent holes 43, 53, ventilation through the filter 20 increases. Cigarette 10 therefore exhibits ventilation due to increased filtration efficiency, pressure drop and increased tar generation. In addition, the cigarette 10 has a relatively flat puff by puff tar profile (based on the combined filtration of the remaining tobacco rod 15 and filter 20).

Although FIG. 1 illustrates one embodiment of the present invention, those skilled in the art will recognize many potential variations of the cigarette 10. For example, filter section 31 and / or 51 may have a plurality of tubes. In addition, the tube or tubes may not necessarily be located along the central axis of the cigarette 10. For example, one possibility would be to have one or more grooves along the outer rim of the filter material 32 and / or 52, or to replace them with tubes 35/55, respectively.

In addition, the filter 20 includes three sections, although in other embodiments additional sections may be present. For example, the filter may have a fourth section similar to the second section and a fifth section similar to the third section. This will then provide further gradual changes in the increase in filter efficiency.

The number, size, shape, material and structure of the tube or groove, the type and density of the filter material, and the number and structure of the filter sections can be adjusted to provide the desired overall filter properties-for example depending on the particular tobacco. It will be appreciated. In addition, although the approach of the present invention has been generally described in terms of tobacco, it may be applied to a wide range of smoking articles, for example cigars. Accordingly, the scope of the invention is defined by the appended claims and their equivalents.

Claims (23)

A smoking article having a filter at one end comprising at least a first section, a second section and a third section disposed continuously along the cylindrical axis of the smoking article:
Each of the first and third sections comprises one or more tubes spanning the length of each section,
The second section comprises a filter material of substantially higher filtration efficiency than the tubes of the first and third sections.
Smoking goods.
The method of claim 1,
At least one tube of the first section is coaxial with at least one tube of the third section
Smoking goods.
The method according to claim 1 or 2,
At least one tube of the first section and at least one tube of the third section are coaxial with the smoking article.
Smoking goods.
The method according to any one of claims 1 to 3,
At least one tube of the first section includes a groove in the outer circumference of the filter
Smoking goods.
The method according to any one of claims 1 to 4,
At least one tube of the third section includes a groove in the outer circumference of the filter
Smoking goods.
6. The method according to any one of claims 1 to 5,
At least one tube of the first section has a length in the range of 4-15 mm.
Smoking goods.
The method according to any one of claims 1 to 6,
At least one tube of the first section has a diameter in the range of 0.1 to 3 mm.
Smoking goods.
The method of claim 7, wherein
At least one tube of the first section has a diameter in the range of 0.5 to 1.5 mm.
Smoking goods.
The method according to any one of claims 1 to 8,
At least one tube of the third section has a length in the range of 4-15 mm.
Smoking goods.
The method according to any one of claims 1 to 9,
At least one tube of the third section has a diameter in the range of 0.1 to 3 mm.
Smoking goods.
The method of claim 10,
At least one tube of the third section has a diameter in the range of 0.5 to 1.5 mm.
Smoking goods.
The method according to any one of claims 1 to 11,
The tube is hollow
Smoking goods.
The method according to any one of claims 1 to 12,
The first filter section other than the one or more tubes comprises a filter material
Smoking goods.
The method of claim 13,
The filter material of the first filter section has a lower filtration efficiency than the filter material of the second filter section.
Smoking goods.
The method according to any one of claims 1 to 14,
The third filter section other than the one or more tubes comprises a filter material
Smoking goods.
The method of claim 15,
The filter material of the third filter section has a higher filtration efficiency than the filter material of the first filter section.
Smoking goods.
The method according to any one of claims 1 to 16,
Ventilation holes are provided outside the second filter section.
Smoking goods.
The method according to any one of claims 1 to 17,
Ventilation is provided outside the third filter section
Smoking goods.
The method according to any one of claims 1 to 18,
The filter comprises additional filter section pairs continuously along the cylindrical axis of the smoking article after the third section, each pair of sections:
A first additional section comprising one or more tubes extending the length of the first additional section substantially parallel to the cylindrical axis of the smoking article; And
A second additional section comprising a filter material of substantially higher filtration efficiency than one or more tubes of the first additional section;
Smoking goods.
The method according to any one of claims 1 to 19,
When using:
The outlet of the one or more tubes in the first section is blocked after the first smoking amount;
The inlet of the one or more tubes in the third section is blocked after an additional amount of smoking
Smoking goods.
The method according to any one of claims 1 to 20,
The tubes run substantially parallel to the cylindrical axis of the smoking article.
Smoking goods.
22. Filter for use in a smoking article according to any of the preceding claims.
A filter for smoking articles,
Generally comprising a cylindrical filter body, the filter body having a first filter section, a second filter section and a third filter section disposed continuously along the filter body,
Each of the first filter section and the third filter section includes one or more tubes spanning the length of each filter section, and the second filter section is substantially higher than the tubes of the first filter section and the third section. Containing filter material of filtration efficiency
Filters for smoking articles.

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