Patent Publication Number: US-8528567-B2

Title: Smoking article having exothermal catalyst downstream of fuel element

Description:
WORKING ENVIRONMENT 
     Traditional cigarettes deliver flavor and aroma to the smoker as a result of combustion, during which a mass of tobacco is combusted at temperatures which often exceeds 800 degrees Celsius during a puff. The heat of combustion releases various gaseous combustion products and distillates from the tobacco. As these gaseous products are drawn through the cigarette, they cool and condense to form an aerosol which provides the tastes and aromas associated with smoking. 
     Traditional cigarettes produce sidestream smoke during smoldering between puffs. Once lit, they must be fully consumed or be discarded. Re-lighting a traditional cigarette is possible but is usually an unattractive proposition to a discerning smoker for subjective reasons (flavor, taste, odor). 
     An alternative to the more traditional cigarettes includes those in which the combustible material itself does not itself release the tobacco aerosol. Such smoking articles may comprise a combustible, carbonaceous heating element (heat source) located at or about one end of the smoking article and a bed of tobacco-laden elements located adjacent the aforementioned heating element. The heating element is ignited with a match or cigarette lighter, and when a smoker draws upon the cigarette, heat generated by the heating element is communicated to the bed of tobacco-laden elements so as to cause the bed to release a tobacco aerosol. While this type of smoking device produces little or no sidestream smoke, it still generates products of combustion at the heat source, and once its heat source is ignited, it is not readily snuffed for future use in a practical sense. 
     Accordingly, it would be desirable to have a smoking article with a low sidestream smoke, which produces an acceptable aerosol and reduces the smoker&#39;s exposure to products of combustion from the heating element or heat source. 
     SUMMARY 
     In accordance with one embodiment, a smoking article comprises: a heat source at a first end of the smoking article; a catalyst adjacent to the heat source, the catalyst capable of catalyzing carbon monoxide from the heat source to carbon dioxide; a filter segment at a second end of the smoking article opposite the first end; and an aerosol generating segment disposed between the catalyst and the filter segment. 
     In accordance with a further embodiment, a smoking article comprises: a heat source at a first end of the smoking article; a catalyst adjacent to the heat source, the catalyst being capable of catalyzing products of combustion from the heat source to a benign substance; a filter segment at a second end of the smoking article opposite the first end; and an aerosol generating segment disposed between the catalyst and the filter segment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an exploded view of a smoking article incorporating a catalyst downstream of the heat source. 
         FIG. 2  shows a longitudinal cross-sectional view of the smoking article of  FIG. 1 . 
         FIG. 3  shows a cross-sectional view of the smoking article of  FIG. 2  along the line  3 - 3 . 
         FIG. 4  shows a cross-sectional view of the smoking article of  FIG. 2  along the line  4 - 4 . 
         FIG. 5  shows a cross-sectional view of the smoking article of  FIG. 2  along the line  5 - 5 . 
         FIG. 6  shows a cross-sectional view of the smoking article of  FIG. 2  along the line  6 - 6 . 
         FIG. 7  shows a cross-sectional view of a reflective liner. 
         FIG. 8  shows a longitudinal cross-sectional view of another embodiment of a smoking article incorporating a catalyst downstream of the heat source. 
         FIG. 9  shows a longitudinal cross-sectional view of a further embodiment of a smoking article incorporating a catalyst downstream of the heat source. 
         FIG. 10  shows a longitudinal cross-sectional view of another embodiment of a smoking article incorporating a catalyst downstream of the heat source. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows an exploded view of a smoking article  10  incorporating a catalyst or catalyst segment  30  adjacent to a fuel element or heat source  20 . In use, the catalyst  30  reduces the smoker&#39;s exposure to products of combustion from the heat source  20  by converting the products of combustion into a benign substance, such as carbon dioxide and water. As shown in  FIG. 1 , the smoking article  10  includes a heat source  20 , a catalyst segment  30  adjacent to the heat source  20 , a filter segment  50  and an aerosol generating segment  40  between the catalyst segment  30  and the filter segment  50 . The heat source  20  is located at a first end  12  of the smoking article  10  with the catalyst segment  30  downstream of the heat source  20 . The filter segment  50  is located at a second end  14  of the smoking article  10  opposite the first end  12  with the aerosol generating segment  40  disposed between the catalyst segment  30  and the filter segment  50 . Herein, the “upstream” and “downstream” relative positions between segments and other features are described in relation to the direction of the products of combustion and aerosols as they are generated and/or formed and drawn from the heat source  20  through the catalyst segment  30 , the aerosol generating segment  40 , and the filter segment  50 . 
     As shown in  FIG. 1 , the heat source  20 , the catalyst segment  30 , and the aerosol generating segment  40  are surrounded or wrapped with a wrapping paper  16 . The wrapping paper  16  preferably will have sufficient porosity to allow air to be admitted through the paper  16  to support combustion within the heat source  20 . Alternatively, the wrapping paper  16  can be perforated  58  ( FIG. 8 ), such as by laser perforation, in the region which surrounds the heat source  20  to allow air into the heat source  20 . 
     In addition, a reflective liner  26  ( FIG. 2 ) can be used to reflect heat from a heat source material  22  back into the heat source  20  to keep it hot and thus ensure that the heat source  20  does not cool below its ignition temperature and become extinguished. Alternatively, the wrapping paper  16  can be treated with a material such as magnesium oxide or other suitable refractory type, cigarette paper to minimize thermal degradation. The filter segment  50  is preferably attached to the heat source  20 , the catalyst segment  30  and the aerosol generating segment  40  by a tipping paper  18 . 
     In use, the smoking article  10  produces an aerosol, which is generated by heat transfer to an aerosol generating material  42  within the aerosol generating segment  40 . In one embodiment, the catalyst segment  30  converts carbon monoxide produced by the heat source  20  to carbon dioxide (and water). In addition, the catalyst segment  30  can produce additional heat, which in combination with the heat generated from combustion within the heat source  20  is transferred to the aerosol generating material  42 . The aerosol generating material  42  releases flavored (or medicant) vapors and gases when contacted by heat (typically, in the form of a heated or hot gas) generated by the heat source  20  and catalyst segment  30 . The vapors then pass into an optional aerosol chamber  44 , forming an aerosol which passes through the filter segment  50  and into the mouth of the smoker. 
       FIG. 2  shows a longitudinal cross-sectional view of the smoking article  10  of  FIG. 1 , which includes the heat source  20 , the catalyst segment  30 , the aerosol generating segment  40  and the filter segment  50 . The heat source  20  includes a heat source material  22 , which generates a heated gas upon combustion. The heat source material  22  can be a carbonaceous material as described in commonly owned U.S. Pat. No. 5,076,296, which is incorporated herein in its entirety, an extracted tobacco filler with an activated carbon or other suitable materials that generate a heated gas. Typically, the heat source material  22  will produce a product of combustion in the form of carbon monoxide, however, it can be appreciated that the heat source  20  can include a heat source material  22  that produces little or no carbon monoxide. 
     In one embodiment, the heat source material  22  can be a carbonaceous material, such as a carbonized material such as pure carbon. Alternatively, the heat source material  22  can a non-carbonized material carbonaceous material, which is not made by carbonizing a carbon source, a charcoal, or other suitable heat generating material. The heat source material  22  also preferably includes an gas or air flow passage in the form of one or more longitudinal passageways  24  extending therethrough for gas or air flow through the heat source material  22  to the catalyst  30 . 
     The catalyst segment  30  is preferably adjacent to the heat source  20  and is comprised of a catalyst material  32  ( FIG. 5 ), which is capable of catalyzing carbon monoxide to carbon dioxide and water. The catalyst material  32  preferably has a low light-off temperature, and is highly reactive to convert the combustion products to carbon dioxide (and water). It can be appreciated that any suitable catalyst material  32 , which is capable of converting combustion products from the heat source  20  to a benign product, such as carbon dioxide can be used. For example, the catalyst material  32  can be a mixed metal oxide, a copper oxide and ceria, or at least one transition metal, such as magnesium oxide (MgO), ferrous oxide (FeO), or zinc oxide (ZnO). 
     The aerosol generating segment  40  includes an aerosol generating material  42 , which when heated, generates or releases an aerosol, which can be drawn in by the smoker. The aerosol generating material  42  is preferably a tobacco-flavored unit in the form of a conventional or hollow cigarette, tobacco pellets, loose shreds or other suitable materials. However, the aerosol generating material  42  can include tobacco condensates or fractions thereof (condensed components of the smoke produced by the combustion of tobacco, leaving flavors and, possibly, nicotine), or tobacco extracts or fractions thereof, deposited on an inert substrate. 
     The aerosol generating material  42  can also include an aerosol-forming material, such as glycerine or water, so that the smoker has the perception of inhaling and exhaling “smoke” as in a conventional cigarette. A particularly preferred material is a composition such as that described in commonly-assigned U.S. Pat. No. 4,981,522, hereby incorporated by reference in its entirety, which describes pelletized tobacco containing glycerine (as an aerosol-forming ingredient) and calcium carbonate (as a filler). 
     In another embodiment, the aerosol generating material  42  can be a reconstituted tobacco product having a burn inhibitor additive to prevent oxidation. It can be appreciated that the aerosol generating material  42  can also include pharmaceutical compositions, medicants, or other flavorants for the delivery of functional ingredients or additives. 
     As shown in  FIG. 2 , the aerosol generating segment  40  can also include an optional aerosol chamber  44 , which is downstream of the aerosol generating material  42 . The aerosol chamber  44  provides length to the smoking article  10  and thus the appearance of a cigarette. In addition, the aerosol chamber  44  provides the smoking article  10  with a chamber or an enclosure for the generation and/or growth of the aerosols from the aerosol generating material  42 . In use, the optional aerosol chamber  44  also improves the overall visibility of the aerosol to the smoker. The aerosol generating chamber  44  preferably has a length of about 15 to 35 mm, so that the smoking article  10  has an overall length of about 70 to 85 mm, which is comparable to a conventional “long-size” cigarette. 
     In an alternative embodiment, the aerosol generating segment  40  comprises only an aerosol generating material  42  without an aerosol chamber ( FIG. 9 ). Typically, if the smoking article  10  does not include an aerosol chamber  44 , the aerosols generated by the aerosol generating material  42  may not be as visible to the smoker as with an aerosol forming chamber  44 . Accordingly, it can be appreciated that an additive within the aerosol generating material  44 , such as glycerine or water can be added to the aerosol generating material  42  to improve the visibility of the aerosols. 
     The filter segment  50  includes a filter material  52 , which can be a starch-based, polypropylene, or plasticized cellulose acetate tow, circumscribed by a plug wrap  54 . The filter material  52  also can have the form of a gathered web (e.g., polypropylene web, polyester web or starch-based web). If desired, the filter material  52  can have at least one cavity, sleeve, sorbent, passage or groove (not shown) extending longitudinally therethrough or partially therethrough. The plug wrap  54  is a paper which optionally incorporates a carbonaceous material. The plug wrap  54  circumscribes the total length of the filter segment  50 . 
     The filter segment  50  is attached to the heat source  20 , catalyst segment  30  and aerosol generating segment  40  by the tipping material  18 , which circumscribes both the entire length of the filter segment  50  and an adjacent region of the aerosol generating segment  40 . The tipping material  18  is typically a paper like product; however, any suitable material can be used. The inner surface of the tipping material  18  is fixedly secured to the outer surface of the plug wrap  54  and the outer surface of the wrapping material  16  of the aerosol generating segment  40 , using a suitable adhesive. The filter segment  50  preferably has a length of about 15 to 25 mm. As shown in  FIG. 2 , the smoking article  10  can include added ventilation or air dilution with a series of ventilation holes or perforations  56  in the filter segment  50 , each of which extend through the tipping material  18  and the plug wrap  54 . 
       FIG. 3  is a cross-sectional view of the smoking article of  FIG. 2  along the line  3 - 3  at the first end  12  of the smoking article  10 . As shown in  FIG. 3 , the first end  12  of the smoking article  10  is preferably provided with a reflective end cap  28 , which attaches to the reflective liner  26  and is covered with the wrapping paper  16 . The cap  28  preferably has at least one or more openings  23  which allow air into the heat source  20 . In use, the cap  28  increases the reflection of the heat or hot gases from the heat source material  22  towards the downstream segments, including the catalyst  30  and aerosol generating material  22 . The cap  28  also prevents the heat source material  22  from falling out of the smoking article  10  if it somehow becomes loose. In addition, the cap  28  retains any ash within the smoking article  10  that may form during burning of heat source material  22 . 
     As shown in  FIG. 3 , the smoking article  10  preferably has an outer diameter  25  of about 7.9 mm, which is similar to a conventional lit end cigarette. The heat source material  22  preferably has a diameter  27  of about 4.0 mm to 5.0 mm with an annular space  21  extending from an inner surface of the reflective sleeve to the outer surface of the heat source material  22 . 
       FIG. 4  is a cross-sectional view of the smoking article of  FIG. 2  along the line  4 - 4 . As shown in  FIG. 4 , the heat source  20  comprises the heat source material  22  having one or more longitudinal passageways  24  extending therethrough, an annular space  21 , and a reflective liner  26 , which is surrounded by the wrapping paper  16 . The reflective liner  26  is also designed to minimize heat loss through the wrapping paper  16 . 
     As shown in  FIG. 4 , the heat source  20  is preferably cylindrical in shape, and fits inside the first end  12  of the smoking article  10 . The heat source  20  includes a heat source material  22 , which can generate enough heat to ensure that the gases flowing therethrough are heated sufficiently to release enough tobacco flavor or other flavorants from the aerosol generating material  42 . For example, if the aerosol generating material  44  is a tobacco product, the heat source material  22  should be able to sufficiently heat the aerosol generating material  44  to release enough tobacco flavor to provide conventional cigarette flavor to the smoker. 
       FIG. 5  is a cross-sectional view of the smoking article of  FIG. 2  along the line  5 - 5 . As shown in  FIG. 5 , the catalyst segment  30  comprises a catalyst material  32 , which is capable of catalyzing carbon monoxide produced by combustion from the heat source  20  to carbon dioxide and water. The catalyst material  32  preferably has a low light-off temperature and high reactivity to convert the combustion products from the heat source  20  to a benign material, such as carbon dioxide. It can be appreciated that any suitable catalyst material  32 , which is capable of converting combustion products from the heat source  20  to a benign or suitable product, such as carbon dioxide (and water) can be used. 
     The catalyst material  32  is preferably a porous material  34 , such that mainstream smoke can pass through the catalyst material  32 . It can be appreciated that the catalyst material  32  can be in the form of a porous disk or cylinder as shown in  FIG. 2  having an approximate thickness or length of about 4 to 5 mm. 
     It can be appreciated that the catalyst material  32 , will preferably be capable of converting carbon monoxide produced by the combustion from the heat source  20  to carbon dioxide and water can be used. For example, the catalyst material  32  can be a mixed metal oxide, a copper oxide and ceria, and at least one transition metal, such as magnesium oxide (MgO), ferrous oxide (FeO), or zinc oxide (ZnO). In an alternative embodiment, the catalyst material  32  can be provided on a support (not shown) of ceria, zirconia, titania, alumina, and/or mixtures thereof or other suitable materials. It can be appreciated that the catalyst material  32  is not limited to the above-mentioned examples, and any suitable catalyst material  32 , which is capable of converting combustion products from the heat source  20  to a benign or suitable product, such as carbon dioxide (and water) can be used. In addition, the catalyst material  32  may provide an addition source of heat to the aerosol generating segment  40 . 
       FIG. 6  is a cross-sectional view of the smoking article of  FIG. 2  along the line  6 - 6 . As shown in  FIG. 6 , the aerosol generating segment  40  comprises a plug or capsule  46  of aerosol generating material  42  and an optional aerosol generating chamber  44  ( FIG. 2 ). The aerosol generating material  42  is preferably a tobacco-flavored unit in the form of a conventional or hollow cigarette, tobacco pellets, loose shreds or other suitable materials. However, the aerosol generating material  42  can include tobacco condensates or fractions thereof (condensed components of the smoke produced by the combustion of tobacco, leaving flavors and, possibly, nicotine), or tobacco extracts or fractions thereof, deposited on an inert substrate. Alternatively, the aerosol generating material  42  can be a plug  46  of shredded reconstituted tobacco leaf having a burn inhibitor such as phosphate salt or other suitable inhibitor to prevent oxidation. 
     As shown in  FIGS. 2-6 , the heat source  20 , the catalyst segment  30  and aerosol generating material  42  are preferably housed in a reflective liner  26 . The reflective liner  26  as shown in  FIG. 7  is preferably comprised of an outer paper layer  37  and an inner foil layer  39 . The foil layer  39  reflects heat radiated from the heat source material  22  back into the heat source material  22  to keep it hot and thus ensure that the heat source material  22  does not cool below its ignition temperature and become extinguished. In addition, the reflective liner  26  minimizes heat loss through the wrapping paper  26 . The inner foil layer  39  can be made from a metallized paper, such as aluminum or other suitable material, which reflects heat radiated from the heat source  20 . 
     The heat source  20  can also include an inner support  33 , which can be folded to secure the heat source material  22  within the heat source  20  and adjacent to the catalyst segment  30 . The inner support  33  also suspends the heat source material  22  away from an interior wall of the reflective liner  26 , leaving an annular space  21 . 
       FIG. 8  shows a longitudinal cross-sectional view of another embodiment of a smoking article  10  incorporating a catalyst  30  downstream of the heat source  20  to convert carbon monoxide produced by the heat source  20  into carbon dioxide and water. As shown in  FIG. 8 , the heat source material  22  can also be surrounded by a tobacco product  29  to provide aroma to the smoking article  10 . The tobacco product  29  is preferably treated with an inhibitor such as phosphoric acid (H 3 PO 4 ), or other suitable materials so that the tobacco does not ignite nor burn. The tobacco product  29  also occupies a portion of the annular space  21  around the downstream portion of the heat source material  22  preventing the heat source material  22  from becoming loose. 
     In addition, as shown in  FIG. 8 , the smoking article  10  can include an air mixing space or segment  60  between the heat source  20  and the catalyst segment  30 . The air mixing space or segment  60  is preferably at least 2 mm in length and more preferably 3 to 7 mm in length and most preferably about 5 mm in length. The air mixing space or segment  60  increases the utilization of catalyst material  32  within the catalyst segment  30 . The air mixing space or segment  60  can also increase the extraction of flavor or aerosols from the aerosol generating material  42  by increasing the heat flow to the aerosol generating material  42 . 
       FIG. 9  shows a longitudinal cross-sectional view of a further embodiment of a smoking article  10  incorporating heat source  20  having an adjacent catalyst segment  30 , which is capable of converting product combustion from the heat source  20  into carbon dioxide (and water), a benign substance, or other suitable products. As shown in  FIG. 8 , the smoking article  10  can include an air mixing space or segment  70  between the catalyst segment  30  and the aerosol generating material  42 . The air mixing space or segment  70  is preferably at least 2 mm in length and more preferably 3 to 7 mm in length and most preferably about 5 mm in length. The air mixing space or segment  70  increases the extraction of flavor or aerosols from the aerosol generating material  42  with an increase heat flow. 
       FIG. 10  shows a longitudinal cross-sectional view of another embodiment of a smoking article  10  incorporating a catalyst  30  downstream of the heat source  20  to convert carbon monoxide produced by the heat source  20  into carbon dioxide and water. As shown in  FIG. 10 , the smoking article  10  includes a heat source  20 , a catalyst  30 , an aerosol generating material  42  and a filter segment  50 . The aerosol generating material  42  as shown in  FIG. 10 , is adjacent to the filter segment  50  and does not include an aerosol generating chamber  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.