Title:
Smoking article with valve
Kind Code:
A1


Abstract:
A smoking article having a cylinder of smoking material, a hollow tube within the cylinder of smoking material, and a filter attached to the cylinder of smoking material. The filter includes an upstream segment containing an aerosol former, a downstream segment containing a sorbent material, and a valve positioned between the upstream segment and the downstream segment. The valve has a first position in which the valve is closed and a second position in which the valve is open and allows the passage of smoke through the filter.



Inventors:
Yoss, Gail L. (Chesterfield, VA, US)
Olegario, Raquel (Richmond, VA, US)
Braunshteyn, Michael (Richmond, VA, US)
Dwyer, Rowland W. (Richmond, VA, US)
Application Number:
12/073542
Publication Date:
01/15/2009
Filing Date:
03/06/2008
Assignee:
Philip Morris USA Inc. (Richmond, VA, US)
Primary Class:
International Classes:
A24D3/04
View Patent Images:



Primary Examiner:
MAYES, DIONNE WALLS
Attorney, Agent or Firm:
BUCHANAN, INGERSOLL & ROONEY PC (ALEXANDRIA, VA, US)
Claims:
What is claimed is:

1. A smoking article comprising: a cylinder of smoking material; a hollow tube within the cylinder of smoking material; and a filter attached to the cylinder of smoking material, the filter comprising: an upstream segment containing an aerosol former; a downstream segment containing a sorbent material; and a valve positioned between the upstream and the downstream segments, wherein the valve includes a first position in which the valve is closed, and a second position in which the valve is open and allows the passage of smoke through the filter.

2. The smoking article of claim 1, wherein the valve is designed to open at a minimum operational pressure and remains open as long as the minimum operational pressure is maintained; or the valve has a predetermined range of operational pressures, and the valve opens at a minimum operational pressure and closes if the operational pressure is higher than a maximum operational pressure.

3. The smoking article of claim 1, wherein the sorbent material is an activated carbon material.

4. The smoking article of claim 1, wherein the upstream and the downstream segments are cellulose acetate tow.

5. The smoking article of claim 2, wherein the sorbent material comprises an activated carbon composition mixed with cellulose acetate fibers.

6. The smoking article of claim 1, wherein the aerosol former is selected from a group comprising glycerin, propylene, glycol, triacetin, propylene carbonate and triethyl citrate.

7. The smoking article of claim 1, wherein the upstream segment is a fibrous material; and the downstream segment of sorbent material is between a pair of segments of cellulose acetate tow.

8. The smoking article of claim 7, wherein the fibrous material is selected from a group comprising crimped paper, modified celluloses, carbon felts and foams, or encapsulated aerosol formers.

9. The smoking article of claim 1, further comprising a plurality of ventilation holes within the filter on a downstream side of the valve.

10. The smoking article of claim 1, further comprising a plurality of ventilation holes within the filter on an upstream side of the valve.

11. A smoking article comprising: a cylinder of smoking material; a hollow tube within the cylinder of smoking material; and a filter attached to the cylinder of smoking material, the filter having a segment containing an aerosol former, a valve having a first position in which the valve is closed, and a second position in which the valve is open and allows the passage of smoke through the filter, and at least one segment of filtering material.

12. The smoking article of claim 11, wherein the valve is designed to open at a minimum operational pressure and remains open as long as the minimum operational pressure is maintained.

13. The smoking article of claim 11, wherein the valve has a pre-determined range of operational pressures, and the valve opens at a minimum operational pressure and closes if the operational pressure is higher than a maximum operational pressure.

14. The smoking article of claim 11, further comprising a plurality of ventilation holes within the filter on a downstream side of the valve; or a plurality of ventilation holes within the filter on an upstream side of the valve

15. A filter for a smoking article comprising: an upstream segment containing an aerosol former; a downstream segment containing a sorbent material; and a valve positioned between the upstream segment and the downstream segments, wherein the valve includes a first position in which the valve is closed, and a second position in which the valve is open and allows the passage of smoke through the filter.

16. The filter of claim 15, wherein the valve is designed to open at a minimum operational pressure and remains open as long as the minimum operational pressure is maintained.

17. The filter of claim 15, wherein the valve has a pre-determined range of operational pressures, and the valve opens at a minimum operational pressure and closes if the operational pressure is higher than a maximum operational pressure.

18. The filter of claim 15, wherein the smoking article is an electrically heated smoking system.

19. The filter of claim 15, wherein the smoking article comprises a cigarette holder and a cigarette.

20. A method of making a smoking article, comprising: forming a tobacco rod portion of the smoking article by placing smoking material between a hollow tube and an outer layer of wrapper paper; forming a filter portion of the smoking article having a plurality of segments comprising an upstream segment containing an aerosol former, a valve having a first position in which the valve is closed, and a second position in which the valve is open and allows the passage of smoke through the filter, and at least one filtering material segment; and joining said tobacco rod portion in end-to-end relationship with the filter portion.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(e) to U.S. provisional Application No. 60/906,117, filed on Mar. 9, 2007, the entire content of which is incorporated herein by reference.

SUMMARY

It would be desirable to have a smoking article having a structure which controls the amount of total particulate matter (TPM) in the mainstream smoke of a smoking article and/or prevents or limits the migration of volatile aerosol formers or other flavorants to other filter components.

In accordance with one embodiment, a smoking article comprises: a cylinder of smoking material; a hollow tube within the cylinder of smoking material; and a filter attached to the cylinder of smoking material, the filter comprising: an upstream segment containing an aerosol former; a downstream segment containing a sorbent material; and a valve positioned between the upstream and the downstream segments, wherein the valve includes a first position in which the valve is closed and a second position in which the valve is open and allows the passage of smoke through the filter.

In accordance with a further embodiment, a smoking article comprises: a cylinder of smoking material; a hollow tube within the cylinder of smoking material; and a filter attached to the cylinder of smoking material, the filter having a segment containing an aerosol former, a valve having a first position in which the valve is closed, and a second position in which the valve is open and allows the passage of smoke through the filter, and at least one segment of filtering material.

In accordance with another embodiment, a filter for a smoking article comprises: an upstream segment containing an aerosol former; a downstream segment containing a sorbent material; and a valve positioned between the upstream segment and the downstream segments, wherein the valve includes a first position in which the valve is closed, and a second position in which the valve is open and allows the passage of smoke through the filter.

In accordance with a further embodiment, a method of making a smoking article, comprises: forming a tobacco rod portion of the smoking article by placing smoking material between a hollow tube and an outer layer of wrapper paper; forming a filter portion of the smoking article having a plurality of segments comprising an upstream segment containing an aerosol former, a valve having a first position in which the valve is closed, and a second position in which the valve is open and allows the passage of smoke through the filter, and at least one filtering material segment; and joining said tobacco rod portion in end-to-end relationship with the filter portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a smoking article according to one embodiment having a tobacco rod with a concentric hollow tube and a filter having a valve.

FIG. 2 is a cross sectional view of a smoking article having a tobacco rod with a concentric hollow tube and a filter having a valve.

FIG. 3 is a cross sectional view of another embodiment of a smoking article having a plurality of ventilation holes or perforations on a downstream side of the valve.

FIG. 4 is a cross sectional view of another embodiment of a smoking article having a plurality of ventilation holes or perforations on an upstream side of the valve.

FIG. 5 is a cross sectional view of another embodiment of a smoking article having a plurality of ventilation holes or perforations about a location on the tobacco rod.

DETAILED DESCRIPTION

As shown in FIG. 1, a smoking article 10 in the form of a cigarette includes a rod 20 of smoking material 21 (FIG. 2), contained in a circumscribing outer wrapper 30. The outer wrapper 30 is typically a porous wrapping material or paper wrapper. The rod 20 is typically referred to as a “tobacco rod” and has a lit end or upstream end 12 and a tipped end 14 at which a filter 40 is attached to the tobacco rod 20. The smoking material 21 is preferably a shredded tobacco or tobacco cut filler. However, any suitable smoking material 21 can be used.

The smoking article 10 also includes a filter 40 adjacent to the tipped end 14 of the tobacco rod 20 such that the filter 40 and tobacco rod 20 are axially aligned in an end-to-end relationship, preferably abutting one another. The filter 40 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 40 are open to permit the passage of air and smoke therethrough.

The filter 40 preferably includes a plurality of filter materials 42, usually circumscribed by a plug wrap or segment wrap 44. The plug or segment wrap 44 is preferably a paper product which optionally incorporates a carbonaceous material. The segment wrap 44 may circumscribe the total length of the filter 40. The filter 40 is attached to the tobacco rod 20 by a tipping paper 50, which circumscribes the filter 40 and an adjacent region of the tobacco rod 20. The tipping paper 50 is typically constructed of a paper web; but, any suitable material can be used. A ventilated or air diluted smoking article 10 can be provided with an air dilution means, such as a series of ventilation holes or perforations 52, each of which extend through the tipping paper 50 and optionally the segment wrap 44.

FIG. 2 shows a cross sectional view of a smoking article 10 having a tobacco rod 20 with a concentric hollow tube 60 and a filter 40 having a valve system 70. The concentric hollow tube 60 can be incorporated into the tobacco rod 20 of the smoking article 10, in such a way that the tube 60 can alter the usual total particulate matter (TPM) delivery profile of a conventional cigarette or smoking article 10. The tobacco rod 20 is comprised of a hollow tube 60, surrounded by a smoking material 21, such as a tobacco filler material, and an outer layer of cigarette wrapper (paper) 30. The hollow tube 60 is preferably centrally or concentrically located within the cylindrical rod 20 of smoking material 21, and having a first end 61 on the lit end 12 of the tobacco rod 20, and a second end 63 on the tipped end 14 of the tobacco rod 20.

The hollow tube 60 preferably extends from the tipped end 14 of the tobacco rod 20 towards the lit end 12 of the tobacco rod 20 with an overall length 64 of about 20 to 100 millimeters. The internal or inner diameter 66 of the hollow tube 60 can vary from about 0.5 to 5.5 millimeters, and is preferably about 1.5 to 3.5 millimeters, and more preferably about 2.0 to 3.0 millimeters for a tobacco rod 20 with an outer diameter 67 of about 6.0 and 10.0 millimeters and an overall length 65 of about 40.0 to 125.0 millimeters. It can be appreciated that one or more non-concentric hollow tubes 60 also can be used. In use, the delivery profile of the smoking article 10 including the amount of tar per puff will generally be determined by the length 64 and the inner diameter 66 of the hollow tube 60, as well as the position of hollow tube 60 within the tobacco rod 20.

As shown in FIG. 2, the lit end 12 of the tobacco rod 20 is fully filled tip 68 with a smoking material 21, which extends from the lit end 12 of the smoking article 10 to the first end 61 of the hollow tube 60 and has an overall length 69 of about 2.0 to 30.0 millimeters. It can be appreciated that the length 69 of the fully filled tip 68 of smoking material 21 can vary depending on the length 65 of the tobacco rod 20 and the desired delivery profile. The second end 63 of the hollow tube 60 is positioned on the tipped end 14 of the tobacco rod 20 adjacent to the filter 40.

The hollow core tube 60 can be constructed in a number of ways, including a blended tobacco cut filler rod, or other combustible materials such as cellulose-based filler, with a hollow center. The walls 62 of the hollow tube 60 can be made out of combustible sheet material such as paper, chemically treated paper, and tobacco-based sheet materials. The sheet materials of the hollow tube 60 can be chemically treated with burn modifiers, ammonium mono-phosphate, flavorants and aerosol formers. Alternatively, the hollow core or tube 60 of the tobacco rod 20 can be molded, extruded or formed of combustible materials such as blended tobacco or cellulose-based materials using suitable binders such as pectin, starch, and guar gum. In addition, it can be appreciated that the hollow tube 60 can be constructed to collapse upon itself during use or alternatively, constructed in a manner wherein the hollow tube 60 does not collapse upon itself during use.

As shown in FIG. 2, the filter 40 includes a first or upstream segment 72 containing an aerosol former 74, a second or downstream segment 76 containing a sorbent material 78, and a valve 70 positioned between the upstream and downstream segments 72, 76. The filter 40 also preferably includes at least one segment of a filtering material 42, and more preferably an upstream and a downstream segment 80, 82 of filtering material 42 surrounding the downstream segment 76 of sorbent material 78. Herein, the “upstream” and “downstream” relative positions between filtering material 42 and other features are described in relation to the direction of mainstream smoke as it is drawn from the hollow tube 60 of the tobacco rod 20 and through the multi-component filter 40.

The aerosol former 74 is preferably a glycerin, propylene glycol, triacetin, propylene carbonate and triethyl citrate or other suitable material and more preferably propylene glycol. It can be appreciated that the upstream segment 72 for the aerosol former 74 can be made of fibrous materials such as crimped paper, modified celluloses, felts and foams, cross-linked polyacrylamide, hydrogels, or suitable material. Additionally, the upstream segment 72 containing the aerosol former 74 can be treated with hydrophobic substances such as waxes and paraffin to reduce loss of aerosol former 74 by evaporation during extended storage.

As described herein, the delivery profile of the smoking article 10 including the amount of tar per puff will generally be determined by the length 64 and the internal diameter 66 of the hollow tube 60, as well as its position within the tobacco rod 20. In addition, the amount of tar per puff is also determined by the amount of aerosol former 74 incorporated into the smoke when heat is transferred to the upstream segment 72 containing aerosol former 74. The amount of aerosol former 74 transferred to the smoke will typically depend on the amount of energy transported to the upstream segment 72 and the nature of the aerosol former 74. In addition, the amount of energy transferred can also be dependent on the geometry of the hollow tube 60, including the length 64 and internal diameter 66, and position of the hollow tube 60 within the tobacco rod 20, as well as the puff duration and volume.

The valve 70 includes a first position, wherein the valve 70 is closed and prevents a passage of smoke or other components through the valve 70, and a second position, wherein the valve is open and allows the passage of smoke through the filter 40. The valve 70 can be a one-way valve designed to open when a small amount of suction is applied and which remains open as long as a minimum operational pressure (or draw rate) is maintained. Alternatively, the valve 70 can be a check valve or other suitable valve arrangement having a pre-determined range of operational pressures, wherein the valve opens at a minimum operational pressure and closes if the applied (draw rate) is higher than a maximum or upper operational pressure.

In a conventional cigarette, a smoker can take puffs of any desired volume or duration, which exposes him or herself to variable amounts of tobacco smoke. This phenomenon is often described as compensation or elasticity; i.e., the smoker's ability to draw an uncontrolled amount of tobacco smoke depending on puff volume, duration and frequency. However, the presence of the valve 70 can minimize compensation or elasticity by regulating the maximum amount of tobacco smoke that the smoker is exposed per puff by introducing an upper limit to puff volume. Accordingly, the valve 70 can include a lower (or minimum operation pressure) and an upper (or maximum operation pressure) limitation of operation, which limits the maximum puff volume. Alternatively, if the smoker draws on the cigarette or smoking article 10 at a flow or draw rate greater than the upper limitation of operation, the valve 70 can limit the maximum smoke volume per puff, by displacing the excess flow of smoke towards a secondary path (not shown) and providing smoke free air via a plurality of ventilation holes and/or perforations 52.

In addition, the valve 70 can be a physical or mechanical barrier, which isolates the tobacco rod 20 and/or aerosol former 74 from the segments 80, 82 of filtering material 42 within the filter 40. In addition, since many aerosol formers 74 are volatile enough to evaporate during prolonged storage, the valve 70 can prevent the migration of the aerosol former 74 to other cigarette filter components, especially to the sorbent material 78. The valve 70 can also increase the shelf life of the smoking article 10 by isolating the volatile aerosol formers 74 and/or flavorants (not shown) from the filtering material 42. It can be appreciated that generally the valve 70 will be closed and acting a physical or mechanical barrier, when the cigarette or smoking article 10 is not lit, or when the draw rate or operational pressure is minimal, for example, when the smoking article 10 is not being puffed.

The valve 70 can also be used as an internal component of an electrically heated smoking system and/or a capillary aerosol application to regulate TPM delivery and puff volumes, including regulating the amount of nicotine per puff. Examples of an electrically heated smoking system are shown in commonly assigned U.S. Pat. Nos. 5,388,594 and 5,692,525, which are incorporated herein by reference. Alternatively, the valve 70 can be placed in cigarette holders to be used in conjunction with conventional cigarettes, wherein the valve 70 limits the maximum puff volume with the advantage of being used for the like of cigarette holders leading to a lower cost cigarette or smoking article 10.

The downstream segment 76 preferably includes a sorbent material 78 in the form of an activated carbon filter. As shown in FIG. 2, the sorbent material 78 is positioned between a pair of segments 80, 82 (i.e., an upstream and downstream segment) of filtering material 42. The filtering material 42 is preferably a cellulose acetate tow filter; however, other suitable filtering materials can be used.

The sorbent material 78 can be in the form of granules, carbon-on-tow (i.e., cellulose acetate with an activated carbon mixed throughout) and the like. In one embodiment, the sorbent material 78 is a high surface area, activated carbon, for example, a coconut shell based carbon of typical ASTM mesh size used in the cigarette industry or finer. Alternatively, the sorbent material 78 can be a bed of activated carbon, which is adapted to adsorb constituents of mainstream smoke, particularly, those of the gas phase including aldehydes, ketones and other volatile organic compounds, and in particular 1, 3 butadiene, acrolein, isoprene, propionaldehyde, acrylonitrile, benzene, toluene, styrene, acetaldehyde, and hydrogen cyanide. With respect to the carbon particles, it is preferred that they have a mesh size of from 10 to 70, and more preferably a mesh size of 20 to 50. It can be appreciated that any suitable sorbent material 78 can be used.

Upon lighting of the smoking article 10, the mainstream smoke is generated by and drawn from the tobacco rod 20 and through the filter 40. The heat from the tobacco rod 20 is convectively transferred with the smoke from the lit end 12 of the tobacco rod 20 of smoking material 21 through the hollow tube 60 to the tipped end 14 of the tobacco rod 20 of smoking material 21 in each puff. It can be appreciated that the smoke from a smoking article 10 having a hollow tube 60 can travel down the hollow tube 60 at temperatures as high as 250 degrees C., even at considerable distances from the lit end 12. Accordingly, the upstream segment 72 having an aerosol former 74, wherein the aerosol former 74 is released by exposure to thermal energy contained within the filter 40. The upstream segment 72 having an aerosol former 74 acts as a heat sink, which prevents the filtering material 42 (typically cellulose acetate) from melting under the heat delivered by the hollow tube 60.

FIG. 3 shows a cross sectional view of another embodiment of a smoking article 10 having a plurality of ventilation holes or perforations on a downstream side of the valve 70. As shown in FIG. 3, the smoking article 10 can have a plurality of ventilation holes or perforations 52, each of which extends through the tipping paper 50 and the plug wrap 44, to provide the smoking article 10 with filter ventilation. As shown in FIG. 3, ventilation of mainstream smoke can be achieved with a circumferential row or rows of ventilation holes or perforations 52 about a location along the filter 40. The filter 40 can include a plurality of ventilation holes or perforations 52 on either the downstream (FIG. 3) and/or the upstream side (FIG. 4) of the valve 70. The ventilation holes or perforations 52 extend through the tipping paper 50 and the segment wrap 44.

In use, as shown in FIG. 3, the valve 70 can be located upstream of the perforations 52. As the flow rate through the valve 70 increases, it pressure drop increases, thereby forcing more flow through the perforations 52 within the filter 40. Alternatively, the valve 70 can include a spring loaded plate or other suitable mechanism (not shown) that moves as the flow rate increases, exposing more perforations, and thereby allowing more flow through the perforations 52.

FIG. 5 shows a cross sectional view of another embodiment of a smoking article 10 having a tobacco rod 20 with a plurality of ventilation holes or perforations 52 on the tobacco rod 20. As shown in FIG. 5, the smoking article 10 can have a plurality of ventilation holes or perforations 52, each of which extends through the wrapper 30 of the tobacco rod 20 providing the smoking article 10 with tobacco rod ventilation.

In accordance with an embodiment, the valve 70 can be placed inside a tubular segment of a low-density cellulose acetate tow (sometimes referred to as a hollow acetate tube or HAT). It can be appreciated that for ease of manufacturing on high-speed filter rod making equipment, the outer diameter of the valve 70 is less than that of the original diameter of the tubular segment prior to filter 40 making operations. Preferably, the diameter of the valve 70 is smaller than the pre-determined diameter of the cigarette to be made. For example, for a smoking article 10 having a circumference of approximately 24.1 mm, the circumference of the valve 70 is preferably, approximately 23.9 mm or less. As is typically done in established filter making techniques, the original diameter of the hollow acetate tow segment is slightly oversized so that it may be uniformly compressed into the desired diameter (e.g. 24.1 mm circumference) during filter making operations and held by application of segment or plug wrap 44.

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.





 
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