Patent Application
20110083687
Heretofore, cigarettes with high levels of ventilation have usually had unacceptably low levels of resistance to draw (RTD) unless some counter measure was in place to make up for the shortfall in RTD. In the past, high-density cellulose acetate filter segments were used to address the short fall. However such filtered segments tended to reduce tar delivery (FTC), with little or no effect upon gas phase components of mainstream tobacco smoke, such as carbon monoxide (CO) and nitrogen oxide (NO). This solution tended to worsen the CO to tar (FTC) ratios in filtered (FTC tar) cigarettes.
Ventilation has a desirable attribute in that, when operating alone, it will reduce both the particulate phase and the gas phase of mainstream smoke. However, highly ventilated cigarettes have drawbacks in resistance to draw (RTD) as previously discussed. It can be appreciated that with a flow restricting orifice in the cigarette filter, the mainstream smoke is forced to flow through the orifice. With the filter ventilation introduced downstream from this orifice, the ventilation level is dependent on the overall resistance to draw (RTD) upstream from the ventilation holes. For a given number of ventilation holes and size, the filter ventilation level increases as the upstream RTD increases. At a given filter efficiency, increased filter ventilation reduces the smoke tar delivery.
In a conventional filtered cigarette, per puff tar delivery increases as smoking progresses through the puff count. This is mainly due to the combination of reduced filtration from the tobacco rod, re-vaporization of tar build up on the tobacco rod from previous puff(s), and a decreased filter ventilation contribution as the puff (char line) progresses and the upstream RTD reduces. The tar delivery of the last puff could be twice as much as the first and/or second puffs. Reducing the degree of change from early to later puffs in principle would permit for a more consistent sensorial experience, and reducing the total tar delivery, without significantly affecting the overall smoking experience.
Accordingly, it would be desirable for a smoking article to address the phenomena of inconsistent smoke deliveries from puff to puff, since it is known that the delivered tar from earlier puffs is less than the delivery of the later puffs.
In accordance with one embodiment, a channeled flow segment is designed such that during the process of smoking the cigarette, the resistance to flow of smoke through a channel within the segment increases as a result of tar accumulation or build-up within the channel. The increased resistance, as smoking progresses, causes the filter ventilation to increase and the delivered tar is decreased in the later puffs. In accordance with another embodiment, the increased resistance to draw (RTD) and filter ventilation during the later puffs can also be designed so that it is difficult to smoke the last few puffs (where tar per puff can be twice as much as the first few puffs) thereby reducing the total tar delivery without significantly impacting the overall smoking experience. In addition, depending on the size (inner diameter) and the length of the flow channel, a desired pressure drop across the segment can be achieved.
Referring to
As shown in
The filter 30 is adjacent to the filter end 14 of the tobacco rod 20 such that the filter 30 and tobacco rod 20 are axially aligned in an end-to-end relationship, preferably abutting one another. The filter 30 preferably has a generally cylindrical shape, and the diameter thereof is essentially equal to the diameter of the tobacco rod 20. The ends (i.e., upstream end 16 and downstream end 18 (i.e., mouth end or buccal end) of the filter 30 are open to permit the passage of air and smoke therethrough.
The filter 30 is preferably attached to the tobacco rod 20 by an outer wrapper or tipping paper 28, which circumscribes both the entire length of the filter 30 and an adjacent region of the tobacco rod 20. The tipping paper 28 is typically a paper like product; however, any suitable material can be used.
As shown in
The channeled flow segment 60 may be constructed of paper, a plastic or a metal and more preferably made of a paper product or a biodegradable plastic or other suitable material having degradability properties. In accordance with a preferred embodiment, the flow channel 62 is generally straight, having a relatively constant diameter such that the channel 62 extends in a continuous direction without bending from an upstream end to a downstream end of the channeled flow segment 60. Alternatively, the flow channel can be a spiral channel, or other suitable configuration.
In accordance with an embodiment, the flow channel 62 is at least in part defined by a cylindrical tubular member 48, which is constructed from a relatively heavy filter plug wrap or paper. The tubular member 48 preferably extends from an upstream end to a downstream end of the segment 60.
It can be appreciated that the channeled flow segment 60 is preferably sized to contribute sufficient pressure drop such that the smoking article 10 presents a resistance to draw of at least 50 mm water or greater, and more preferably in the range of 70-120 mm water. It can be appreciated that as the channeled flow segments 60 becomes clogged, the resistance to draw and/or flow through the flow channel 62 increases due to the tar build up. Preferably, the channeled flow segment 60 has a diameter of approximately 7.0 to 8.0 mm, and more preferably approximately 7.4 to 7.8 mm.
In accordance with one embodiment, a tubular body segment 64 at least partially defining a portion of a cavity 66 is situated between the mouthpiece filter 50 and the flow channel 62 of the channeled flow segment 60. The filter 30 can also include a second upstream tubular body portion (not shown) that spaces the channeled flow segment 60 a predetermined distance apart from the first filter segment 40.
The smoking article 10 also preferably includes a ventilating zone 70 comprised of a first row (and optionally second and possibly third rows) of ventilation holes or perforations 72, each of which extend through the tipping paper 28, the plug wrap 26 and the tubular body segment 64.
Preferably the ventilating zone 70 is located near or adjacent to the channeled flow segment 60 so that air drawn through the ventilation zone 70 is allowed to mix with the mainstream smoke from the flow channel 62 before arriving at the mouthpiece filter segment 50. The distance between the ventilating zone 70 and the mouthpiece filter segment 50 is preferably at least 5 mm and more preferably in the range of 5-12 mm. In accordance with a preferred embodiment, the holes or perforations 72 of the ventilating zone 70 achieve a ventilation level of the smoking article 10 of at least 25% and more preferably at least 50% to 90%.
During an initial puff or puffs, mainstream smoke is drawn from the lit end through the tobacco rod 20 to the downstream end of the filter 30, and drawn through the flow channel 62. Thus, by the time of subsequent puffs on the smoking article 10, the flow channel 62 is partially blocked. It can be appreciated that the resistance to draw (RTD) and the flow distribution of the flow channel 62 can be depend on several factors including the length of the filter 30 and the flow channel 62, the inner diameter of the flow channel 62, and the nature or type of filter materials within the first filter segment 40 and the mouthpiece segment 50.
The first filter segment 40 and the mouthpiece filter segment 50 are preferably a starch-based, polypropylene, or plasticized cellulose acetate tow, filter paper or other suitable material. The first filter segment 40 and the mouthpiece segment 50 can also be constructed from a gathered web (e.g., polypropylene web, polyester web, cellulosic web or starch-based web).
In accordance with a preferred embodiment, as the smoking progresses, tar gradually builds up inside and at the ends of the flow channel 62. Resistance to flow through the flow channel 62 increases due to the tar build up as shown in
In accordance with an embodiment, the increased resistance to draw (RTD) and filter ventilation during the later puffs can also be designed so that it is difficult to smoke the last few puffs. It is generally accepted that the first few puffs or earlier puffs are more important in terms of the smoking experience, and wherein the reduced tar deliveries in the last few puffs from this novel filter design can have overall tar reduction with minimum impact on the smoking experience. It can also be appreciated that the flow channel 62 can be fine tuned to control the tar build up, by adjusting or changing the size of the channel 62, including the length and diameter thereof, so that the resistance-to-draw (RTD) is acceptable and ventilation of the filter 30 achieves desired tar delivery from the smoking article 10.
In accordance with another embodiment, the flow channel 62 can include or be coated with a material 49 (
In accordance with another embodiment, as shown in
It is to be appreciated that in all embodiments, the filter 30 may be constructed from simple combining techniques typically used in the industry for manufacturing cigarettes at high speeds. Additionally each embodiment includes support about the cavity 66 to provide desired firmness throughout length of the filter 30.
It will be understood that the foregoing description is of the preferred embodiments, and is, therefore, merely representative of the article and methods of manufacturing the same. It can be appreciated that many variations and modifications of the different embodiments in light of the above teachings will be readily apparent to those skilled in the art. Accordingly, the exemplary embodiments, as well as alternative embodiments, may be made without departing from the spirit and scope of the articles and methods as set forth in the attached claims.
