Patent Application
20080216851
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 shortfall. 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 lower delivery (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. Highly ventilated cigarettes however have drawbacks in RTD as previously discussed.
During a puff on a smoking article incorporating a restrictor in the filter and an aerosol former such as glycerin in the tobacco rod, such glycerin vaporizes, introducing glycerin and water into the mainstream tobacco smoke and diluting particulate phase constituents present in the smoke. The particulate phase includes phenolics, such as catechol, hydroquinone, phenol and tobacco-specific nitrosamines (TSNA). For a given level of FTC tar delivery, any glycerin, being part of the particulate phase, will, in effect, displace other particulate phase constituents that would have otherwise originated from the combustion of tobacco during a puff. Some aerosol formers, such as glycerin, act as a tar diluent and if present in sufficient quantity may also act as a phenol control agent to further reduce phenol levels in mainstream smoke beyond the levels attributable solely to dilution.
Smoke constituents can also be reduced with ventilated filters. 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, cigarettes with high levels of ventilation have usually had unacceptably low levels of resistance to draw (RTD) unless some counter measure is in place. One solution to this problem with RTD was to include high density cellulose acetate filter segments. However, such high density filter segments tended to reduce tar delivery (FTC), with little or no effect upon gas phase constituents of mainstream tobacco smoke, such as carbon monoxide (CO) and nitrogen oxide (NO). This solution tends to worsen the CO to tar (FTC) ratios especially in lower delivery (FTC tar) cigarettes.
On the other hand, cellulose acetate filter segments comprising cellulose acetate tow and triacetin plasticizer are known to be effective in removing phenols and cresols from mainstream cigarette smoke. Any substantial reduction in the mass or density of such filter segments has tended to create higher proportional constituency levels in mainstream smoke of phenols and cresols on a per unit tar (FTC) basis.
Thus, there is a need in the art for a smoking article having a highly ventilated filter with an acceptable RTD and with both an improved CO to FTC tar ratio and reductions in phenols and cresols.
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In an embodiment, the cut filler includes a reconstituted tobacco sheet having a high glycerin content. Preferably, about 10% to about 80% of the smokeable material (cut filler) in the tobacco rod 12 is of reconstituted tobacco sheet. More preferably, the tobacco rod includes about 30% to about 50% of the reconstituted tobacco sheet, and more preferably about 35% to about 45%. However, in other embodiments, the cut filler does not include a reconstituted tobacco sheet, but includes enhanced glycerin levels applied to the cut filler.
The reconstituted tobacco sheet is cut into smokeable filler material for a smoking article. Preferably, the reconstituted tobacco sheet includes up to about 50% w/w of glycerin. In an embodiment, additional cut tobacco filler material is also incorporated into the tobacco rod 12.
The aqueous slurry 560 is subjected to a separation process 580 to produce a solubles portion 600 and a fibrous portion 620. For example, aqueous slurry 560 can be compressed or centrifuged to remove the solubles portion 600. Preferably, the solubles portion 600 is not reincorporated into the reconstituted tobacco manufacturing process, but discarded.
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After the paper-making process 660 has been completed, the tobacco sheets are subjected to a moisture reduction process 680 to reduce the moisture content of the sheet. Preferably, the moisture content is reduced to less than 50% by weight, but greater than 30% by weight. In other exemplary embodiments, the moisture content is reduced to less than 45% by weight, less than 40% by weight, or less than 35% by weight. For example, the sheets can be placed on a steam-heated metal drum (i.e., Yankee dryer) to reduce the moisture content and optionally followed by smaller steam-heated surface dryers (i.e. can dryers).
After the moisture reduction process 680, an aerosol former solution 720 is applied to the sheet. For example, the sheets can be passed through a size press 700, in which the sheets are fed between two vertical or horizontal rollers, configured to apply an aerosol former solution 720 to both sides of the sheet. The aerosol former solution 720 can include other additives 740. In alternative embodiments, the aerosol former solution 720 can be sprayed onto the sheet, or the sheet can be immersed in the aerosol former solution 720.
Examples of aerosol formers include glycerin, propylene glycol, ethylene glycol, dipropylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and/or oleyl alcohol.
In one embodiment, an aerosol former solution 720 is incorporated into the sheet at a temperature below about 40° C. In other exemplary embodiments, the aerosol former solution 720 is incorporated into the sheet at temperatures below about 35° C., e.g., below about 30° C. or 25° C., or at ambient temperature.
Glycerin is a preferred aerosol former for aerosol former solution 720. Glycerin forms an inert aerosol of glycerin and water vapor when present in a combusting tobacco rod of a smoking article. For example, the glycerin aerosol former can be incorporated into the sheet as an aqueous glycerin solution containing about 20% to 80% glycerin by volume. In alternative embodiments, the glycerin solution can contain about 50 to 80% glycerin by volume. Preferably, the aqueous glycerin solution contains between about 75% to about 80% by volume glycerin. Attempts to use a solution of about 100% glycerin results in poor absorption of the glycerin into the tobacco material, resulting in a tacky surface, which can present difficulties in the manufacturing process.
The aerosol former solution 720 can also contain other additives 740, such as flavorants, humectants (other than glycerin), and/or acetate compounds. Examples of flavorants include licorice, sugar, isosweet, cocoa, lavender, cinnamon, cardamom, apium graveolens, fenugreek, cascarilla, sandalwood, bergamot, geranium, honey essence, rose oil, vanilla, lemon oil, orange oil, mint oils, cassia, caraway, cognac, jasmine, chamomile, menthol, cassia, ylang-ylang, sage, spearmint, ginger, coriander, coffee and the like. Examples of humectants other than glycerin include propylene glycol and the like.
Tobacco materials with a higher concentration of glycerin may also contain optional additives. Acetates have been identified as possibly promoting reduction in TPM cytotoxicity of tobacco smoke, especially in combination with glycerin. Acetate compounds may further enhance the reduction of TPM or phenolics in the smoke of a combusted smoking article. In one embodiment, the acetate compound includes ammonium acetate, calcium acetate, and/or magnesium acetate. The one or more acetate compounds are added in an amount effective to promote the reduction of catechol, hydroquinone, phenol, or TSNA in the smoke of a combusted smoking article incorporating the sheet as a cut filler.
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In one embodiment in which the aerosol former solution 720 is glycerin, the glycerin solution is added in an amount effective to produce a non-tacky sheet upon drying. In another embodiment, the glycerin solution is added in an amount up to about 50% by weight of the tobacco sheet after drying.
Ammonium acetate can be incorporated into the tobacco sheet preferably in an amount between about 5% to about 20% by weight of the sheet after drying, or more preferably about 10% to about 12%. In lieu of or in addition to ammonium acetate, calcium acetate can be incorporated in an amount preferably between about 1% to about 10% by weight of the sheet after drying, and more preferably about 4%. In lieu of or in addition to ammonium acetate and/or calcium acetate, magnesium acetate can be incorporated in an amount preferably between about 5% to about 20% by weight of the sheet after drying, and more preferably about 8% to about 10%.
After the drying process 760, the sheet containing an aerosol former (e.g., glycerin, propylene glycol, manitol, sorbitol) can be shredded into a cut filler and incorporated into a smoking article. The overall reduction in the tobacco originated TMP is proportional to the amount of glycerin incorporated in a smoking article as part of the cut filler.
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In this embodiment, the ventilation zone 40 comprises a plurality of ventilation holes 41 which extend through the tipping paper 16 and preferably, through the tubular filter segment 48. Accordingly, the material of the filter segment 48 is preferably cellulosic so that it can be laser perforated via online laser perforation techniques (or other perforating techniques) to provide ventilation holes during the manufacture of the smoking article 10. In the alternative, the ventilation holes are established in only the tipping paper 16 (either by using pre-perforated tipping paper or on-line perforating techniques), and the tubular segment 48 is sufficiently air-permeable to establish communication between the vent holes 41 and the cavity 46. Preferably, other perforating techniques may also be used, such as mechanical (pin) perforation techniques and/or electrostatic techniques and the like.
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Preferred dimensions for an exemplary 83 mm smoking article include, for example, a filter length of approximately 27 mm, a mouth end filter segment length of approximately 7 mm, vent holes that are located approximately 12 mm from the mouth end of the smoking article, a restrictor disc length of approximately 5 mm, a cellulose acetate tow segment length of approximately 2.5 mm, and a carbon on tow filter segment length of approximately 7 mm.
The ventilation zone 40 is established with a first row (and optionally second and possibly third rows) of ventilation holes through the tipping paper 16 and preferably through filter tube 48′. Accordingly, air is preferably drawn through the ventilation holes of ventilation zone 40 and into the cavity 46 defined between the flow restriction 30 and the mouthpiece filter segment 22.
Preferably the ventilation zone 40 is located near or adjacent to the flow restriction 30 so that air drawn through the ventilation zone 40 is allowed to mix with the mainstream smoke before arriving at the mouthpiece filter 22. Preferably, the distance between the ventilation zone 40 and the mouthpiece filter 22 is at least 5 mm or in the range of 5-12 mm. Also preferably, the flow restriction 30 is spaced approximately 4 mm to 15 mm from the mouthpiece filter 22, more preferably approximately 6 to 10 mm. These features help minimize impaction of the particulate phase smoke constituencies at the mouthpiece filter 22, which in turn, helps maintain the desired CO to tar (FTC) ratios.
Preferably, the ventilation zone 40 achieves a ventilation level of the smoking article of at least 25% and more preferably at least 50% to 90%.
Furthermore, the embodiments provide a desired amount of resistance to draw while maintaining the desired degree of high ventilation throughout the puff count. The latter attribute is achieved by placement of the ventilation zone 40 downstream of the flow restriction 26. Furthermore, placing the ventilation along the cavity assures mixing of air drawn into the filter through the ventilation zone with mainstream smoke drawn from the tobacco rod.
The restrictor disc 26 may comprise a partition (transverse wall having one or more orifices therein) that establishes the flow restriction 30, with the partition including an orifice of reduced diameter. The partition may be frustoconical and convergent either into or away from the direction of flow of mainstream smoke passing therethrough. Furthermore, a pair of partitions may be arranged internally within the restrictor disc 26 so as to provide end to end symmetry for the restrictor disc 26. A filter component having end to end symmetry facilitates high speed filter rod making in that the component works the same whether or not the rod making machine orients one end of the component first or reverses it.
A restrictor disc 26 having end to end symmetry has tubular body portions of equal length on opposite sides of a transverse wall (partition). By such arrangement manufacture of the filter is facilitated by the end to end symmetry of the restrictor disc 26.
Optionally, a second zone of ventilation may be located upstream of the flow restriction 30 in addition to the ventilation zone 40 as provided above.
Manufacture of the smoking articles 10 described above is facilitated with the use of pre-perforated tipping paper.
Preferably the flow restriction 30 is sized to contribute sufficient pressure drop such that the smoking article 10 presents a resistance to draw of at least 70 mm water or greater, preferably in the range of 90-120 mm water. In an embodiment, the flow restriction 30 is 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, preferably in the range of 60-90 mm water. Preferably, the partition (transverse wall) has a diameter of approximately 7.0 to 8.0 mm and more preferably approximately 7.4 to 7.8 mm wherein the partition preferably has one or optionally, at least one orifice of a diameter of about 0.5 mm to about 0.9 mm and more preferably about 0.5 to 0.7 mm. Since the pressure drop of the restrictor component depends on the open area, multiple orifices can also be used. For example, in one embodiment there are two orifices in the partition of approximately 0.5 mm diameter each.
The restrictor disc 26 may be constructed of paper, a plastic, polymer or a metal and more preferably made of a paper product or a biodegradable plastic/polymer or other suitable material having degradability properties. However, in the case of plastic being used, the restrictor disc 26 is small and the non-biodegradable content of the filter is minimized.
An advantage of the filter designs described above is that the filter may be constructed from simple combining techniques typically used in the industry for manufacturing cigarettes at high speeds. Additionally each embodiment includes tubular support about the cavity 46 so as to provide desired firmness throughout the length of the filter 14.
Furthermore, the embodiments provide the necessary amount of resistance to draw while maintaining the desired degree of high ventilation throughout the smoke. The latter attribute is achieved by placement of the ventilation zone 40 downstream of the flow restriction 30.
Furthermore, placing the ventilation in ventilation zone 40 in spaced apart relation to the mouthpiece filter plug 22 assures mixing of air drawn into the filter 14 through the ventilation zone 40 with mainstream smoke drawn from the tobacco rod 12. In one tested embodiment, uniform stain patterns appeared at the buccal end of the mouthpiece filter 22, which is indicative of good mixing.
During smoking of a cigarette constructed in accordance with the present disclosure, a desired degree of ventilation (e.g., 50 to 90%, preferably about 60% or about 70%) is preferably maintained throughout the smoke.
Cellulose acetate filters (CA) with triacetin as plasticizer are known to remove phenol and cresols from mainstream cigarette smoke when compared to non-filter cigarettes on an equal tar basis. The present restrictor filter design reduces the amount of such CA in a filter by about 50% (e.g., conventional cigarette with a 27 mm filter versus an equivalent restrictor filter with 10 mm to 14 mm of such CA segments). The reduction of CA results in an apparent increase in levels of phenols per unit tar (FTC) and cresols per unit tar (FTC) compared to conventional CA filters, although the phenol/tar and cresols/tar ratios in the restrictor filter design are still lower than that of non-filter cigarettes on an equal tar basis. To counteract that effect, an aerosol former such as glycerin is added to tobacco cut filler to compensate for and decrease the cresols/tar and the phenols/tar ratios, i.e. the addition of glycerin serves to counteract the relative increase of phenol/tar and cresols/tar ratios in smoking articles containing lesser amounts of plasticized CA.
Beyond expected reduction due to dilution standing alone, glycerin has an additional effect on phenol and polyphenolics (which include catechol and hydroquinone), which is believed to be a tendency for glycerin in the tobacco rod to reduce the levels of these compounds by some chemical and/or physical mechanism. Glycerin is an agent that is both a tar diluent and an agent that mechanistically further reduces particulate phase smoke constituents such as hydroquinone and catechol by its presence in a tobacco rod. The restrictor/glycerin combination can be applied to any delivery level or “tar category” (FTC tar) and at any desired level of tar diluent.
Preferably, the addition of glycerin in a tobacco rod is at a level sufficient to counteract the tendency of phenols to pass through low particulate efficiency CA filter segments at a greater rate than they do with conventional CA filters.
Table 2 discloses the tar content, both under FTC conditions and the more stringent Massachusetts test, of a smoking article of a preferred embodiment including 7% glycerin in cut filler and a filter including cellulose acetate upstream an downstream filter segments, a flow restrictor therebetween, and a cavity downstream of the flow restrictor in communication with a ventilation zone. FTC smoking conditions include 35 ml puffs of 2 second duration every 60 seconds. Massachusetts smoking conditions include 45 cc puffs of 2 second duration every 30 seconds, with 50% of the ventilation blocked.
From the above, it is noteworthy that CO/tar values remained low.
Cigarettes of certain embodiments may yield less than about 0.9, often less than about 0.5, and usually between about 0.05 and about 0.3 FTC “tar” per puff on average when smoked under FTC smoking conditions. Such cigarettes are “ultra low tar” cigarettes which yield less than about 7 mg FTC “tar” per cigarette. Typically, such cigarettes yield less than about 9 puffs, and often about 6 to about 8 puffs, when smoked under FTC smoking conditions.
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It is noteworthy that highly ventilated restrictor cigarettes with 7% glycerin achieved smoke constituent reductions the same or better that 45 mg activate carbon. The filter achieves the smoke constituent reduction desired by carbon-filter cigarettes without the taste penalty associated with carbon-filters.
In addition, Table 3 shows the effect of the restrictor filter design including an upstream cellulose acetate plug and enhanced glycerin levels (about 7%) on gas phase constituents of mainstream cigarette smoke with and without activated carbon included in the filter.
By including carbon, either on paper or on CA tow, upstream of the ventilation holes the presence of VOC, carbonyls, and the gas vapor phase were reduced beyond cigarettes containing no activated carbon in addition to the restrictor and 7% glycerin levels.
Table 4 discloses the concentration of particulate phase constituents of a smoking article of a preferred embodiment including 7% glycerin in cut filler and a filter including cellulose acetate upstream an downstream filter segments, a flow restrictor therebetween, and a cavity downstream of the flow restrictor in communication with a ventilation zone as compared smoking articles including a standard amount of glycerin, about 2%, and a filter including cellulose acetate upstream an downstream filter segments, a flow restrictor therebetween, and a cavity downstream of the flow restrictor in communication with a ventilation zone.
As shown in Table 4, the concentration of particulate phase constituents of a smoking article of a preferred embodiment including 7% glycerin in cut filler is reduced as compared to the commercially available low FTC Tar smoking articles including a standard amount (2%).
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 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.
This application claims priority under 35 U.S.C. §119(e) to U.S. provisional Application No. 60/905,835, filed on Mar. 9, 2007, the entire content of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60905835 | Mar 2007 | US |
