Smoking article comprising ultrafine particles

FIELD OF THE INVENTION

[0001] The present invention relates generally to smoking articles, including cigarettes, and more particularly to smoking articles comprising ultrafine particles. Embodiments of the present invention include cigarettes comprising a combustible material component wherein the combustible material component comprises ultrafine particles. The ultrafine particles may comprise materials such as metal oxides, ceramics and/or ultrafine particles having other chemical structures. In an embodiment, ultrafine particles may be utilized to reduce the amount of carbon monoxide in the smoke.

BACKGROUND OF THE INVENTION

[0002] Cigarettes are popular smoking articles that use tobacco in various forms. Descriptions of cigarettes and the various components thereof are set forth in Tobacco Production, Chemistry and Technology, Davis et al. (Eds.) 1999.

[0003] Cigarettes generally include a substantially cylindrical rod shaped structure and include a charge, roll or column of smokable material such as shredded tobacco (e.g., in cut filler form) surrounded by a paper wrapper thereby forming a so-called “tobacco rod.” Normally, a cigarette has a cylindrical filter element aligned in an end-to-end relationship with the tobacco rod. Typically, a filter element includes cellulose acetate tow circumscribed by plug wrap, and is attached to the tobacco rod using a circumscribing tipping material. It also has become desirable to perforate the tipping material and plug wrap, in order to provide dilution of drawn mainstream smoke with ambient air.

[0004] Numerous cigarettes and cigarette-type smoking articles that employ carbonaceous components have been proposed. Some of those carbonaceous materials have been prepared by pyrolyzing, catalytically degrading or oxidizing cellulosic materials. See, for example, U.S. Pat. No. 3,545,448 to Morman; U.S. Pat. No. 3,461,879 to Kirkland; U.S. Pat. No. 3,482,578 to Briskin; U.S. Pat. No. 4,002,176 to Anderson; U.S. Pat. No. 4,079,742 to Rainer et al.; U.S. Pat. No. 4,256,126 to Seligman et al.; and U.S. Pat. No. 4,534,371 to White. The disclosure of each of these patents is incorporated herein by reference.

[0005] There has been the suggestion that carbonaceous materials can be incorporated as components of the smokable blends of cigarettes. See, for example, U.S. Pat. No. 3,738,374 to Bennett; U.S. Pat. No. 4,014,349 to Morman et al.; U.S. Pat. No. 4,044,777 to Boyd et al.; U.S. Pat. No. 4,008,723 to Borthwick et al.; U.S. Pat. No. 4,326,544 to Hardwick et al.; U.S. Pat. No. 4,920,990 to Lawrence et al.; U.S. Pat. No. 5,074,321 to Gentry et al.; and U.S. Pat. No. 5,092,353 to Montoya et al. The disclosure of each of these patents is incorporated herein by reference.

[0006] There also has been the suggestion that carbonaceous materials can be used in the formation of smoking article components having specific shapes. See, for example, U.S. Pat. No. 2,907,686 to Siegel; U.S. Pat. No. 4,219,031 to Rainer; U.S. Pat. No. 4,340,072 to Bolt et al.; U.S. Pat. No. 4,481,958 to Rainer; U.S. Pat. No. 4,771,795 to White; U.S. Pat. No. 4,969,476 to Bale et al.; and U.S. Pat. No. 5,105,835 to Drewett; and PCT WO 99/34697. The disclosure of each of these patents is incorporated herein by reference.

[0007] There also has been suggestion that carbonaceous materials can be employed as components of combustible material components that are designed to burn and provide heat to aerosolize physically separate aerosol forming materials. See, for example, U.S. Pat. No. 4,708,151 to Shelar et al.; U.S. Pat. No. 5,016,654 to Bernasek et al.; U.S. Pat. No. 4,991,596 to Lawrence et al.; U.S. Pat. No. 5,038,802 to White et al.; U.S. Pat. No. 4,793,365 to Sensabaugh et al.; U.S. Pat. No. 4,961,438 to Korte; U.S. Pat. No. 4,991,606 to Serrano et al.; U.S. Pat. No. 5,020,548 to Farrier et al.; U.S. Pat. No. 5,076,297 to Farrier et al.; U.S. Pat. No. 5,148,821 to Best et al.; U.S. Pat. No. 5,178,167 to Riggs et al.; U.S. Pat. No. 5,183,062 to Clearman et al.; U.S. Pat. No. 5,345,955 to Clearman et al.; U.S. Pat. No. 5,551,451 to Riggs et al.; and U.S. Pat. No. 5,595,577 to Bensalem et al. The disclosure of each of these patents is incorporated herein by reference. See, also, Chemical and Biological Studies on New Cigarette Prototypes that Heat Instead of Burn Tobacco, R. J. Reynolds Tobacco Company Monograph (1988).

[0008] Cigarettes having carbonaceous combustible material components have been marketed by the R. J. Reynolds Tobacco Company under the tradenames Premier and Eclipse. It also has been suggested to incorporate catalytic materials into the carbonaceous combustible material components of certain types of smoking articles. See, for example, U.S. Pat. No. 5,040,551 to Schlatter et al.; U.S. Pat. No. 5,211,684 to Shannon et al.; U.S. Pat. No. 5,240,014 to Deevi et al.; and U.S. Pat. No. 5,258,340 to Augustine et al. The disclosure of each of these patents is incorporated herein by reference.

[0009] Cigarettes and cigarette-like tobacco articles are employed by the smoker by lighting one end thereof and burning the tobacco rod, or igniting the fuel source and aerosolizing components in the aerosol generating rod. The smoker then receives mainstream smoke into his/her mouth by drawing on the opposite end (e.g., the filter end) of the cigarette.

[0010] It would be desirable to have the means to modify the performance attributes of a smoking article employing carbonaceous components. It would also be desirable to provide a manner or method for altering the combustion properties and/or combustion by products of carbonaceous materials used for the manufacture of smoking articles.

SUMMARY OF THE INVENTION

[0011] The present invention relates to smoking articles that deliver good flavor, pleasure and satisfaction. In particular the present invention relates to smoking articles comprising thermally generated aerosol technologies, the smoking articles comprising nanoparticles.

[0012] In an embodiment the present invention provides smoking articles comprising a combustible material to provide an aerosol and/or to heat an aerosol forming material, the smoking articles comprising ultrafine particles. The ultrafine particles may be incorporated into the combustible material, insulating material, adjacent components, porous structure adjoining and in intimate contact with the combustible material or other component parts of the smoking article. The location and position of the ultrafine particles may be selected such that specific performance properties of the smoking article are modified. For example, in an embodiment of the present invention wherein it is desired to modify the composition of mainstream smoke, ultrafine particles are located/positioned within the smoking article such that there is contact between the ultrafine particles and the mainstream smoke. An example of such an embodiment includes modification of smoke to reduce levels of carbon monoxide in the smoke.

[0013] In a preferred embodiment of the present invention, the combustible material component comprises ultrafine particles. The regions comprising ultrafine particles may be selected such that they advantageously modify performance attributes of the smoking article.

[0014] Included among combustible materials and carbonaceous materials are forms of tobacco. Accordingly, in an aspect, the present invention provides embodiments of smoking articles wherein a tobacco component of a smoking article comprises ultrafine particles. Details of these embodiments are set forth below.

[0015] As used herein, the term “aerosol” is meant to include vapors, gases, particles, and the like, both visible and invisible, and especially those components perceived by the smoker to be “smoke-like,” formed by the action of heat generated by the combustible material component upon materials contained within the aerosol generating means, or elsewhere in the smoking article.

[0016] As used herein, the terminology ultrafine particle refers to particles having dimensions less than 10,000 nanometers, including nanoparticles and slightly larger particles. The term nanoparticle is generally used to indicate particles with dimensions less than 100 nanometers (one nanometer is one billionth of a meter). Ultrafine particles manifest advantageous and unique properties which can be exploited in embodiments of the present invention for a variety of purposes relating to the performance properties of a tobacco article such as a cigarette.

[0017] The composition of ultrafine particles suitable for use in the present invention includes, but is not limited to, metal oxides, ceramics, carbon containing compositions, polymeric compositions, semiconductor compositions and the like. The ultrafine particles may be doped or coated. Further details relating to the composition of ultrafine particles are set forth below.

[0018] Embodiments of the present invention include, but are not limited to embodiments: utilizing ultrafine particles to modify components of the smoke, for example converting carbon monoxide to carbon dioxide, exploiting the sintering properties of ultrafine particles to form zones of reduced oxygen access and/or altered thermal properties; catalyzing reactions in the burning cigarette that modify the combustion process; exploiting the ability of ultrafine particles to alter combustion (e.g., in conjunction with water) and/or modifying the thermal properties of the smoking articles.

[0019] In embodiments of the present invention, the ultrafine particles may be incorporated into the component parts of a smoking article by a variety of methods, including those set forth in detail below and other methods that will be recognized by those of ordinary skill in the art.

[0020] Embodiments of the present invention preferably tend to burn at a desirable rate, in order to provide a desirable number of puffs. Further, preferred embodiments do not provide an undesirable off-taste and off-aroma to the mainstream and sidestream smoke generated thereby; and are capable of generating relatively low levels of visible sidestream smoke when the wrapping materials are of a suitably low air permeability.

[0021] Further details relating to the present invention, and its advantages, are set forth in the following sections.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]
FIG. 1 is a perspective view of an embodiment of a smoking article of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention is directed to improvements in smoking articles and in particular to improvements in smoking articles comprising a combustible material and a physically separate aerosol generating means.

[0024] In one aspect the present invention provides tobacco articles, for example cigarettes, incorporating a combustible material comprising ultrafine particles. Preferred tobacco articles of the present invention include embodiments wherein the combustible material comprises a short extruded carbonaceous element comprising ultrafine particles. The length of the carbonaceous element is typically from 3 mm to about 20 mm, preferably about 5 mm to about 16 mm and most preferably about 6 mm to about 12 mm in length prior to burning.

[0025] The combustible material may be retained within a cigarette of the present invention by an insulating jacket. Preferably the insulating jacket circumscribes the entire longitudinal periphery of the combustible material, although it may extend beyond each end of the material, effectively recessing the material and separating it from the other components of the cigarette. The preferred resilient nature of the insulating jacket allows it to extend into any grooves on the periphery of the combustible material. The insulating jacket also aids in retaining heat and permits radial atmospheric air to flow to the combustible material during use.

[0026] In one especially preferred embodiment, the resilient insulating means comprises a fibrous material which circumscribes the longitudinal periphery of the combustible material component. The fibrous material may comprise glass fibers (“C” glass from Owens-Corning is especially preferred), a tobacco filler/glass fiber mixture, gathered or shredded tobacco paper, gathered or shredded carbon paper, tobacco cut filler, or the like.

[0027] The combustible material may include one or more longitudinal grooves extending along its outer periphery and a centrally located axial hole. Such grooves assist in lighting of the combustible material component and allow heated air to flow along the periphery of the material. The grooves also tend to assist in retaining the combustible material within the jacket.

[0028] In another aspect, the present invention provides a smoking article comprising an ultrafine particle component. The ultrafine particle component comprises ultrafine particles and may be incorporated into a smoking article as a discrete component. The ultrafine particle component may be used to modify the performance properties of a smoking article and/or the chemical properties of the smoke produced by the article.

[0029] In an embodiment of the present invention, an ultrafine particle component comprises a porous structure, the porous structure comprising ultrafine particles. The porous structure may take a variety of geometric forms, including, but not limited to, a tube, a sphere, a column, a disc, and similar structures. In cigarette embodiments of a smoking article of the present invention, the porous structure may have a geometric form that will allow the porous structure to fit in the internal volume of the cigarette.

[0030] A preferred porous structure is a porous disc, the porous disc comprising ultrafine particles. The porous disc may be located in a smoking article adjacent a combustible material, for example between the combustible material and the mouth end of the smoking article. The ultrafine particles may be applied to the internal surfaces of the porous structure by a variety of methods, or may be an integral part of the structure itself. The structure preferably serves as an inert support of the ultrafine particles and further serves to provide maximum surface area at an appropriate pressure drop. The ultrafine particle disc structure may be utilized to catalyze the oxidation of carbon monoxide to carbon dioxide in the hot gas stream leaving the combustible material.

[0031] In another embodiment, the ultrafine particle porous structure may take the form of an insulating sleeve around the longitudinal periphery of the carbonaceous fuel. The sleeve may extend the entire length of the fuel, or a greater or lesser length.

[0032] In another embodiment, the ultrafine particle-porous structure may take the form of a combination insulation/disc assembly into which a carbonaceous fuel is fitted. In this embodiment, the porous structure serves both to insulate the fuel and catalyze desired reactions in the hot air stream, including oxidation of carbon monoxide to carbon dioxide in sidestream smoke.

[0033] A smoking article of the present invention may further comprise a filter element and a tipping material. The filter element may be positioned adjacent one end of the aerosol-generating rod, the tipping material circumscribing the filter element and an adjacent region of the aerosol generating rod. Smoking articles having filters comprising cellulose acetate filter tow are particularly preferred. Smoking articles having filters comprising cellulose acetate filter tow and carbon are also preferred. The smoking articles are also preferably air diluted.

[0034] Suitable combustible materials, and processes for preparing them include the processes, combustible materials and combustible fuel sources set forth in U.S. Pat. No. 5,099,861 “Aerosol Delivery Article” to Clearman et al.; U.S. Pat. No. 4,793,365 “Smoking Article” to Sensabaugh et al.; U.S. Pat. No. 4,991,596 “Smoking Article” to Lawrence et al.; U.S. Pat. No. 4,756,318 “Smoking Article With Tobacco Jacket” to Clearman et al.; U.S. Pat. No. 5,020,548 to Farrier et al.; U.S. Pat. No. 5,345,955 to Clearman et al., U.S. Pat. No. 5,148,821 to Best et al.; U.S. Pat. No. 5,551,451 to Riggs et al., and U.S. Pat. No. 5,076,297 to Farrier et al. the disclosure of each of which is incorporated herein by reference. Additional examples are set forth in U.S. Pat. Nos. 5,016,654; 4,991,596; 5,038,802; and/or 4,708,151. The disclosure of each of these patents is hereby incorporated herein by reference.

[0035] In general suitable combustible materials for embodiments of the present invention include, but are not limited to, carbonaceous materials.

[0036] As used herein, carbonaceous refers to consisting primarily of carbon. Carbonaceous materials include at least 50%, by weight, preferably 60-95%, more preferably 70-80%, by weight carbon. Carbonaceous materials may include other materials including binders, other metallic particles, such as aluminum, or the like. The carbonaceous materials may be in powder form and may be activated. Preferred carbonaceous materials may be heat treated. Preferred combustible materials of the present invention comprise greater than 50%, by weight, carbon and further comprise ultrafine particles.

[0037] Carbonaceous materials may be produced from natural or synthetic cellulose (e.g. pulp), tobacco, rayon, fibrous materials, wood and/or other sources.

[0038] Carbonaceous materials may be used in many different components of a smoking article. Embodiments of the present invention, include any use of a carbonaceous material comprising ultrafine particles. Examples of uses of carbonaceous materials in smoking articles suitable for embodiments of the present invention comprising ultrafine particles include, but are not limited to those set forth in U.S. Pat. Nos. 4,079,742; 3,885,575; 5,105,835; 4,534,371; 4,920,990; 5,074,321; 4,942,888 and/or 5,092,353. The disclosure of each of these patents is hereby incorporated herein by reference.

[0039] In the production of a cigarette of the present invention, a carbonaceous mass may be extruded into a continuous rod of a desired shape, laid directly onto a ribbon of insulating material which is circumscribed by a wrapper to form a jacketed continuous rod. The jacketed continuous rod is cut into appropriate length. During manufacturing, an aqueous liquid is applied in an appropriate amount to the carbonaceous rod and/or insulating material which assists in bonding the carbonaceous rod to the insulating material upon drying to an appropriate moisture. In embodiments of the present invention, the aqueous liquid may comprise ultrafine particles.

[0040] Further details relating to the construction of a smoking article comprising a combustible material of the present invention are provided in U.S. Pat. No. 5,819,751, to Barnes et al., issued Oct. 13, 1998, the disclosure of which is hereby incorporated herein by reference.

[0041] In an embodiment of the present invention, a combustible material component of a smoking article may comprise 0.01% to 20%, by weight, preferably 0.01 to 2%, by weight ultrafine particles.

[0042] The ultrafine particles may be applied to formed carbonaceous combustible materials or combustible material constituent materials. Methods of application to formed combustible materials include wash coating, dipping, painting, spraying or other methods known to those skilled in the art. Methods of application to constituent materials include mixing dry, solution or suspension forms with a fuel slurry or other methods known to those skilled in the art. In another embodiment, ultrafine particles may be applied to the surface of micro structures (e.g. fibers) prior to the incorporation of the micro-structures in the formed combustible material.

[0043] Ultrafine particles in the dry powder form (e.g. nanopowder) may be mixed directly in a carbon mix along with other dry ingredients for extrusion. Alternatively, the nanopowder may be suspended in a liquid and the suspension mixed with the extrudate. Similar procedures may be followed for pressed combustible materials.

[0044] In another embodiment, a combustible material component is formed, for example by extruding or pressing, without ultrafine particles. A sol comprising ultrafine particles is sprayed on the material prior to drying. Alternatively a dried combustible material may be wash coated with a sol containing ultrafine particles in an appropriate concentration. Wash coating is an effective way of distributing ultrafine particles evenly on the surface of a preferred combustible material such as described above, as the capillary action of the grooves and the centrally located axial hole ensure an even distribution on the surfaces that are most active during combustion.

[0045] In another embodiment, ultrafine particles may be applied to an insulating mat, to a porous structure adjoining the combustible material, or to a combination thereof. In these embodiments, ultrafine particles may be applied in dry powder or suspension forms, or by other methods familiar to those skilled in the art.

[0046] Ultrafine particles comprise metal oxides, including, but not limited to: silica (SiO2), magnesium oxide (MgO), titania (TiO2), alumina (e.g. Al2O3), iron oxide (e.g. FeO, Fe3O4 and Fe2O3), hydrated aluminum oxide (AlOOH), zinc oxide (ZnO), ceria (CeO2), gold oxide (AuO & Au2O) and zirconia (ZrO2). Ultrafine particles may also comprise mixed oxides, such as indium-tin oxide (e.g. In2O3—SnO2 or ITO) and antimony-tin oxide (ATO), as well as titanates, particularly barium titanate (BaTiO3). As will be understood by those of ordinary skill in the art, the valence states of the metal ions in the foregoing metal oxides can vary, thus the present invention should not be construed as limited to the particular examples of metal oxides set forth above. In addition, ultrafine particles may comprise other materials including carbon, various complex oxides, metals, polymers, semiconductors and nonoxide ceramics. Further, the ultrafine particles may be doped with platinum, palladium, rodium, gold and/or other catalytic materials.

[0047] Embodiments of the present invention may comprise a plurality of ultrafine particles having a similar composition, e.g. comprising the same metal oxide. Alternatively, embodiments of the present invention may comprise a mixture of ultrafine particles having different compositions, e.g. a mixture of various metal oxides.

[0048] Ultrafine particles may be produced by a variety of methods including sol-gel synthesis, inert gas condensation, mechanical alloying or high-energy ball milling, plasma synthesis, and electrodeposition. Using such methods, ultrafine particles can be produced in various symmetric shapes, such as spheres, cylinders, prisms, cubes, tetrapods and amorphous clusters. In embodiments of the present invention, the physical properties of ultrafine particles, including for example, their electrical, optical, chemical, mechanical, and magnetic properties, may be selectively controlled for example by engineering the size, morphology, and/or composition of the ultrafine particles. The resulting materials may have enhanced or entirely different properties from their parent materials.

[0049] Representative types of ultrafine particles and materials suitable for use in the present invention are of the type, and may be produced by the methods, described in U.S. Pat. No. 5,006,248 to Anderson et al., U.S. Pat. No. 5,096,745 to Anderson et al., U.S. Pat. No. 5,269,926 to Webster et al., U.S. Pat. No. 6,503,475 to McCormick et al., U.S. Pat. No. 6,472,459 to Morales et al., U.S. Pat. No. 6,467,897 to Wu et al., U.S. Pat. No. 6,479,028 to Kaner et al., U.S. Pat. No. 6,479,146 to Caruso et al., and U.S. Pat. No. 6,479,156 to Schmidt et al.; U.S. Pat. No. 5,169,576 to Anderson et al. and US Published Pat. Applications 2002/0194958 to Lee et al., 2002/014453 to Lilly Jr., et al., 2003/0000538 to Bereman et al., 2002/0167118, 2002/0172826 and 2002/0127351, the disclosure of each patent and published application being incorporated herein by reference.

[0050] In addition to the assignees of some of the aforementioned patents and patent applications, ultrafine particles are commercially available from sources including Nanopowder Enterprise Inc. of Piscataway, N.J. 08854.

[0051] With reference to a cigarette as a smoking article, the cigarette further includes an aerosol-generating means which includes a substrate and at least one aerosol-forming material. A preferred aerosol-generating means includes an aerosol forming material (e.g., glycerin), tobacco in some form (e.g., tobacco powders, tobacco extract or tobacco dust) and other aerosol-forming materials and/or tobacco flavoring agents, such as cocoa, licorice and sugar. The aerosol-forming material generally is carried in a substrate material, such as a reconstituted tobacco cut filler or by a substrate such as tobacco cut filler, gathered paper, gathered tobacco paper, or the like.

[0052] Preferably the substrate is a reconstituted tobacco cut filler cast sheet material, which is formed into a continuous rod or substrate tube assembly on a conventional cigarette making machine. Typically the overwrap material for the rod is a barrier material such as a paper foil laminate. The foil serves as a barrier, and is located on the inside of the overwrap. Alternatively, the substrate may be a gathered paper formed into a rod or plug. When the substrate is a paper-type material, it is highly preferred that such substrate be positioned in a spaced apart relationship from the combustible material component. A spaced-apart relationship is desired to minimize contact between the combustible material component and the substrate, thereby preventing migration of the aerosol forming materials to the fuel, as well as limiting the scorching or burning of the paper substrate. The spacing is normally provided during manufacture of the cigarette in accordance with one method of making the present invention. Appropriately spaced substrate plugs are overwrapped with a barrier material to form a substrate tube assembly having spaced substrate plugs therein. The substrate tube assembly is cut between the substrate plugs to form substrate sections. The substrate sections include a tube with a substrate plug and void(s), preferably at each end.

[0053] The barrier material for making the tube aids in preventing migration of the aerosol former to other components of the cigarette. The barrier material forming the tube is a relatively stiff material so that when formed into a tube it will maintain its shape and will not collapse during manufacture and use of the cigarette.

[0054] An appropriate length of the jacketed combustible material component is combined with a substrate section or substrate tube assembly by a wrapper material, which has a propensity not to burn, to form a fuel/substrate section. In preferred embodiments of the cigarettes, the wrapper typically extends from the mouthend of the substrate section, over a portion of the jacketed combustible material component, whereby it is spaced from the lighting end of the combustible material component. The wrapper material assists in limiting the amount of oxygen which will reach the burning portion of the combustible material component during use, preferably thereby causing the combustible material component to extinguish after an appropriate number of puffs. In especially preferred embodiments of the cigarette, the wrapper is a paper/foil/paper laminate. The foil provides a path to assist in dissipating or transferring the heat generated by the combustible material component during use. The jacketed combustible material component and the substrate section are joined by the overwrap.

[0055] A tobacco section is preferably formed by a reconstituted tobacco cut filler rod, made on a typical cigarette making machine, and cut into appropriate lengths. A filter rod is formed and cut into appropriate lengths for joining to the tobacco section to form a mouthend section. The fuel/substrate section and the mouthend section are joined by aligning the reconstituted ends of each section, and overwrapped to form a cigarette.

[0056] When a paper substrate is used, a tobacco paper rod and a reconstituted cut filler rod are preferably formed and cut into appropriate lengths and joined to form a tobacco section. The tobacco section and the fuel/substrate section are joined by aligning the tobacco paper plug end of the tobacco section with the substrate end of the fuel/substrate section and joining the sections with a wrapper which extends from the rear end of the tobacco roll to an appropriate length past the junction of the two sections for forming the tobacco roll/fuel assembly. The tobacco roll/fuel assembly is then joined to a filter by a tipping material.

[0057] In certain embodiments of the cigarettes of the present invention convective heating is preferably the predominant mode of energy transfer from the burning combustible material component to the aerosol-generating means disposed longitudinally behind the combustible material component. When a foil/paper laminate is used as an overwrap to join the fuel/substrate section some heat may be transferred to the substrate by the foil layer. As described above, the heat transferred to the substrate volatilizes the aerosol-forming material(s) and any flavorant materials carried by the substrate, and, upon cooling, these volatilized materials are condensed to form a smoke-like aerosol which is drawn through the cigarette during puffing, and which exits the filter piece.

[0058] As discussed above, among the embodiments of the present invention are included embodiments wherein a tobacco component of a smoking article comprises ultrafine particles. Also included are embodiments wherein ultrafine particles are in intimate contact with the tobacco component of a smoking article. The ultrafine particles may be placed in intimate contact with the tobacco component, and/or incorporated within the tobacco component during processing of the tobacco, manufacture of the smoking article and/or in additive packages applied to the tobacco using techniques understood by those of ordinary skill in the art and referenced below.

[0059] In the case of processed tobacco, the tobacco component may comprise 1% to 10%, by weight, typically 3% to 7%, by weight, preferably 4% to 6%, by weight ultrafine particles. The ultrafine particles may be admixed with tobacco; mixed with tobacco extract; added to tobacco pulp; sprayed on the tobacco in a sol; incorporated within a casing material applied to the tobacco; applied as a top dressing to the tobacco; mixed with the tobacco expansion fluid; extruded with other tobacco ingredients; included with water solubles, for example in a tobacco denicotinization process; and/or incorporated in a variety of other methods that will be understood to those of ordinary skill in the art of tobacco production.

[0060] Ultrafine particles may be incorporated, for example using an ultrafine particle slurry, into processed tobacco materials such as the cast sheets described in U.S. Pat. Nos. 4,033,359; 4,674,519; 5,099,864; 5,101,839; 5,327,917; 5,339,838; 5,598,868; 5,715,844; and/or 6,216,706. The disclosure of each of these patents is hereby incorporated herein by reference.

[0061] Ultrafine particles may similarly be incorporated during production of reconstituted tobaccos by paper making processes, for example by incorporation into the tobacco pulp and/or as part of an aqueous extract applied during the paper making process. Examples of paper making processes, suitable for use in producing a tobacco component comprising ultrafine particles of the present invention include, but are not limited to, those described in U.S. Pat. Nos. 4,962,774; 4,987,906; 5,143,097; 5,325,877; 5,501,237; 5,445,169; 5,056,537; 5,322,076; 4,270,552; 4,341,228; 4,421,126; 4,706,692; 4,182,349; 4,308,877; 4,289,147; 5,377,698; 5,533,530; 3,847,164; 4,131,117; 5,056,537; 4,887,618; and/or 4,941,484. The disclosure of each of these patents is hereby incorporated herein by reference.

[0062] Ultrafine particles may be incorporated during an extrusion process for reconstituting tobacco, for example as a component in a starch solution, or by admixing during extrusion. Examples of extrusion processes, suitable for use in producing a tobacco component comprising ultrafine particles for an embodiment of the present invention include, but are not limited to, those described in U.S. Pat. Nos. 4,880,018; 5,129,409; 4,347,855; and/or 4,391,285. The disclosure of each of these patents is hereby incorporated herein by reference.

[0063] Ultrafine particles may be incorporated with tobacco, for example with water soluble solids, during a tobacco processing to form re-equilibrated solubles of tobacco, for example in a tobacco denicotinization process. Examples of processes suitable for use in producing a tobacco component comprising ultrafine particles for an embodiment of the present invention include, but are not lmited to, those described in U.S. Pat. Nos. 5,025,812; 5,065,775; 5,234,008; 5,360,022 and/or 5,131,414. The disclosure of each of these patents is hereby incorporated herein by reference.

[0064] Ultrafine particles may be incorporated with tobacco during a tobacco expansion process, for example by including with a carbon dioxide expanding gas. Examples of processes suitable for use in producing a tobacco component comprising ultrafine particles for an embodiment of the present invention include, but are not lmited to, those described in U.S. Pat. Nos. 5,259,403; and/or 5,908,032. The disclosure of each of these patents is hereby incorporated herein by reference.

[0065] Ultrafine particles may be incorporated with tobacco as a component of a casing or top dressing, for example by spraying, topical application and/or other similar top dressing techniques. Examples of processes suitable for use in producing a tobacco component comprising ultrafine particles for an embodiment of the present invention include, but are not lmited to, those described in U.S. Pat. Nos. 3,419,015; and/or 4,877,619. The disclosure of each of these patents is hereby incorporated herein by reference.

[0066] Ultrafine particles may be incorporated with a tobacco in the form of a reconstituted tobacco sheet as an inner wrap material in a smoking article comprising a double wrap configuration. Examples of processes suitable for use in producing a tobacco wrap component comprising ultrafine particles for an embodiment of the present invention include, but are not limited to, those described in U.S. Pat. No. 5,220,093, the disclosure of which is hereby incorporated within by reference. Ultrafine particles may also be incorporated in carbonaceous materials utilized as inner wrap materials as described in U.S. Pat. Nos. 3,744,496; 4,505,282; 4,225,636; and/or 5,159,944. The disclosure of each of these patents is hereby incorporated herein by reference.

[0067] As explained above, in the alternative, or in addition, to their use in other components of a smoking article, ultrafine particles may be used in intimate contact with tobacco, a carbonaceous component, a combustible component and/or another aerosol generating component. In an embodiment of a smoking article of the present invention ultrafine particles may be incorporated as a part of a carbonaceous material used in a filter component. Examples of carbonaceous materials used in a filter components are described in U.S. Pat. Nos. 5,101,839; 5,271,419; 5,360,023; 5,404,890; and/or 5,598,819. The disclosure of each of these patents is hereby incorporated herein by reference.

[0068] Reference is made below to specific embodiments of the present invention, one of which being illustrated in the accompanying drawing. Each embodiment is provided by way of explanation of the invention, not as a limitation of the invention. In fact it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a further embodiment. Thus, it is intended that the present invention cover such modifications and variations as come within the scope of the appended claims and their equivalents.

[0069] The invention is described in more detail with reference to a particular smoking article, namely a cigarette utilizing a carbonaceous combustible material component comprising ultrafine particles. As will be understood by those of ordinary skill in the art, however, the principals of the present invention apply to other tobacco articles.

[0070]
FIG. 1 depicts an embodiment of a smoking article of the present invention. The cigarette 2 includes a combustible material component 10 circumscribed within a retaining jacket of insulating material 12. The combustible material component 10, includes ultrafine particles 11. As will be realized from the foregoing description, the actual size of a typical ultrafine particle may be less than 100 nm, therefore the ultrafine particles would not be visible to the naked eye within the combustible material component.

[0071] Situated longitudinally behind the combustible material component 10 is an aerosol generating means, 16. The aerosol generating means comprises one or more aerosol forming materials (such as glycerin), a form of tobacco (such as tobacco powder, extract or dust), and flavor components, which are volatilized by heat generated by the burning of the combustible material component. Preferably, the aerosol generating means comprises a substrate advantageously made from a reconstituted tobacco cast sheet cut filler material. Such substrates are described in U.S. patent application Ser. No. 07/800,679, filed 27 Nov., 1991, which is incorporated herein by reference.

[0072] The cigarette may further comprise a filter element 18 or other suitable mouthpiece positioned adjacent one end of the aerosol generating means 16 such that the filter element and tobacco rod are axially aligned in an end-to-end relationship, preferably abutting one another. Filter element 18 has a generally cylindrical shape, and the diameter thereof is essentially equal to the diameter of the tobacco rod. The ends of the filter element are open to permit the passage of air and smoke therethrough. The filter element 18 may include a filter material which is overwrapped along the longitudinally extending surface thereof with circumscribing plug wrap material. The filter element can have two or more filter segments, and/or flavor additives incorporated therein.

[0073] The cigarette is typically circumscribed by a wrapping material. The wrapping material has a width which is equal to the circumference of the cigarette plus the lap zone of the glue line which ultimately results during cigarette manufacture. Suitable wrapping materials are generally known to those of ordinary skill in the art and described in patent application referenced above and the following US patents, each of which is incorporated herein by reference, U.S. Pat. No. 4,452,259 to Norman; U.S. Pat. No. 5,878,754 to Peterson et al.; U.S. Pat. No. 5,103,844 to Hayden et al.; U.S. Pat. No. 5,060,675 to Milford et al.; U.S. Pat. No. 4,998,541 to Perfetti et al.; U.S. Pat. No. 4,805,644 to Hampl, Jr. et al.; U.S. Pat. No. 4,461,311 to Matthews et al.; U.S. Pat. No. 4,450,847 to Owens; 4,420,002 to Cline; and U.S. Pat. No. 4,231,377 to Cline et al.

[0074] Paper wrapping materials suitable for use in carrying out the present invention are commercially available. Representative cigarette paper wrapping materials have been available as Ref. Nos. 419, 454, 456, 460 and 473 Ecusta Corp.; Ref. Nos. Velin 413, Velin 430, VE 825 C20, VE 825 C30, VE 825 C45, VE 826 C24, VE 826 C30 and 856 DL from Miquel; Tercig LK18, Tercig LK24, Tercig LK38, Tercig LK46 and Tercig LK60 from Tervakoski; and Velin Beige 34, Velin Beige 46, Velin Beige 60, and Ref. Nos. 454 DL, 454 LV, 553 and 556 from Wattens. Exemplary flax-containing cigarette paper wrapping materials have been available as Grade Names 105, 114, 116, 119, 170, 178, 514, 523, 536, 520, 550, 557, 584, 595, 603, 609, 615 and 668 from Schweitzer-Mauduit International. Exemplary wood-pulp containing cigarette paper wrapping materials have been available as Grade Names 404, 416, 422, 453, 454, 456, 465, 466 and 468 from Schweitzer-Mauduit International.

[0075] In certain embodiments of the present invention a wrapping material for the smoking article may comprise ultrafine particles as described in the commonly assigned, co-pending patent application entitled “Smoking Article Wrapping Materials Comprising Ultrafine Particles”, by Crooks et al., U.S. patent application Ser. No. 10/342,618, the disclosure of which is incorporated herein by reference.

[0076] The filter element 18 is attached to the tobacco rod by a tipping material which circumscribes both the entire length of the filter element and an adjacent region of the tobacco rod. The inner surface of the tipping material is fixedly secured to the outer surface of the plug wrap and the outer surface of the wrapping material of the tobacco rod, using a suitable adhesive. A ventilated or air diluted smoking article is provided with an air dilution means, such as a series of perforations, each of which extend through the tipping material and plug wrap.

[0077] A conventional automated cigarette rod making machine useful for manufacturing cigarettes of the present invention is of the type commercially available from Molins PLC or Hauni-Werke Korber & Co. KG. For example, cigarette rod making machines of the type known as Mark 8 (commercially available from Molin PLC) or PROTOS (commercially available from Hauni-Werke Korber & Co. KG) can be employed, and can be suitably modified if desired. A description of a PROTOS cigarette making machine is provided in U.S. Pat. No. 4,474,190, at col. 5, line 48 through col. 8, line 3, which is incorporated herein by reference. Types of equipment suitable for the manufacture of cigarettes also are set forth in U.S. Pat. No. 4,844,100 to Holznagel; U.S. Pat. No. 5,156,169 to Holmes et al. and U.S. Pat. No. 5,191,906 to Myracle, Jr. et al.; and PCT WO 02/19848. Designs of various components of cigarette making machines, and the various materials used to manufacture those components, will be readily apparent to those skilled in the art of cigarette making

[0078] The cigarette typically has a length which ranges from about 50 mm to about 100 mm, and a circumference of about 16 mm to about 28 mm. The aerosol generating means and the resulting cigarettes can be manufactured in any known configuration using known cigarette making techniques and equipment. The wrapping material is formed into a circular shape such that the ends of the sides thereof abut one another. The ends of wrapping material can abut one another, nearly abut one another, or slightly overlap one another. A cigarette rod having such a configuration can be provided by supplying a paper wrapper from a bobbin on a suitably equipped cigarette making machine, passing the wrapping material through the garniture region of the cigarette making machine, and forming the tobacco rod.

[0079] Typically, the filter element has a length which ranges from about 5 mm to about 35 mm and a circumference of about 16 mm to about 28 mm. Typically, the filter element has a length which ranges from about 5 mm to about 40 mm, preferably about 10 mm to about 35; and a circumference of about 17 mm to about 27 mm, preferably about 22 mm to about 25 mm. The filter element can have a wide range of filtration efficiencies. The filter element can have one segment of filter material, two or more longitudinally positioned segments, or other configurations. The filter may also include an axially located hole to form a hollow filter element.

[0080] The filter material can be any suitable material such as cellulose acetate, polypropylene, tobacco material, or the like. The filter material may further comprise carbon, for example carbon particles. Examples of suitable filter materials are cellulose acetate tow items having (i) about 3 denier per filament and about 35,000 total denier, and (ii) about 3.5 denier per filament and about 35,000 total denier. Such tow items conveniently provide filter elements exhibiting a removal efficiency of particulate matter from mainstream smoke of greater than about 40 weight percent. The plug wrap typically is a conventional paper plug wrap, and can be either air permeable or essentially air impermeable. However, if desired, a nonwrapped cellulose acetate filter element can be employed. Filter elements having two or more segments, and which are provided using known plug-tube-combining techniques, also can be employed. The various filter elements suitable for use in this invention can be manufactured using known cigarette filter making techniques and equipment. Certain filter elements can provide minimal mainstream smoke removal efficiencies while maintaining the desirable draw characteristics of the cigarette. Such minimal smoke removal efficiencies are provided by the so-called “low efficiency” filters. Low efficiency filters have a minimal ability to remove mainstream smoke particulates. Generally, low efficiency filters provide about 40 weight percent mainstream smoke particulate removal efficiency or less. The low efficiency filter can be used in order that the relatively low “tar” yield is obtained primarily as a result of a relatively high level of filter ventilation or air dilution. Such cigarette configurations provide a means for reducing the yields of mainstream gaseous components. An example of a suitable material for providing a low efficiency filter element is a cellulose acetate tow item having about 8 denier per filament and about 40,000 total denier.

[0081] The tobacco materials used for the manufacture of cigarettes of the present invention can vary. Descriptions of various types of tobaccos, growing practices, harvesting practices and curing practices are set forth in Tobacco Production, Chemistry and Technology, Davis et al. (Eds.) (1999). The tobacco normally is used in cut filler form (e.g., shreds or strands of tobacco filler cut into widths of about {fraction (1/10)} inch to about {fraction (1/60)} inch, preferably about {fraction (1/20)} inch to about {fraction (1/35)} inch, and in lengths of about ¼ inch to about 3 inches). The amount of tobacco filler normally used within a cigarette ranges from about 0.6 g to about 1 g. The tobacco filler normally is employed so as to fill the tobacco rod at a packing density of about 100 mg/cm3 to about 300 mg/cm3, and often about 150 mg/cm3 to about 275 mg/cm3. Tobaccos can have a processed form, such as processed tobacco stems (e.g., cut-rolled or cut-puffed stems), volume expanded tobacco (e.g., puffed tobacco, propane-expanded tobacco and dry ice expanded tobacco (DIET)), or reconstituted tobacco (e.g., reconstituted tobaccos manufactured using paper-making type or cast sheet type processes).

[0082] Typically, tobacco materials for cigarette manufacture are used in a so-called “blended” form. For example, certain popular tobacco blends, commonly referred to as “American blends,” comprise mixtures of flue-cured tobacco, burley tobacco and Oriental tobacco, and in many cases, certain processed tobaccos, such as reconstituted tobacco and processed tobacco stems. The precise amount of each type of tobacco within a tobacco blend used for the manufacture of a particular cigarette brand varies from brand to brand. See, for example, Tobacco Encyclopedia, Voges (Ed.) p. 44-45 (1984), Browne, The Design of Cigarettes, 3rd Ed., p.43 (1990) and Tobacco Production, Chemistry and Technology, Davis et al. (Eds.) p. 346 (1999). Other representative tobacco blends also are set forth in U.S. Pat. No. 4,924,888 to Perfetti et al.; U.S. Pat. No. 5,056,537 to Brown et al.; and U.S. Pat. No. 5,220,930 to Gentry; and Bombick et al., Fund. Appl. Toxicol., 39, p. 11-17 (1997). See, also, PCT WO 02/37990.

[0083] As used herein, “packing density” means the weight of the filler material which occupies a unit volume within the smokable rod. For articles of this invention, the packing density generally ranges from about 100 mg/cm3 to about 300 mg/cm3, more typically from about 150 mg/cm3 to about 275 mg/cm3.

[0084] If desired, in addition to the aforementioned tobacco materials, the tobacco blend of the present invention can further include other components. Other components include casing materials (e.g., sugars, glycerine, cocoa and licorice) and top dressing materials (e.g., flavoring materials, such as menthol). The selection of particular casing and top dressing components is dependent upon factors such as the sensory characteristics that are desired, and the selection of those components will be readily apparent to those skilled in the art of cigarette design and manufacture. See, Gutcho, Tobacco Flavoring Substances and Methods, Noyes Data Corp. (1972) and Leffingwell et al., Tobacco Flavoring for Smoking Products (1972).

[0085] Smoking articles also can incorporate at least one flavor component within the side seam adhesive applied to the wrapping material during the manufacture of the tobacco rods. That is, For example, various flavoring agents can be incorporated in a side seam adhesive CS-2201A available from National Starch, and applied to the seam line of the wrapping material. Those flavoring agents are employed in order to mask or ameliorate any off-taste or malodor provided to the smoke generated by smoking articles as a result of the use of the wrapping materials of the present invention. Exemplary flavors include methyl cyclopentenolone, vanillin, ethyl vanillin, 4-parahydroxyphenyl-2-butanone, gamma-undecalactone, 2-methoxy-4-vinylphenol, 2-methoxy-4-methylphenol, 5-ethyl-3-hydroxy-4-methyl-2(5H)-furanone, methyl salicylate, clary sage oil and sandalwood oil. Typically, such types of flavor components are employed in amounts of about 0.2 percent to about 6.0 percent, based on the total weight of the adhesive and flavor components.

[0086] Typically, the tipping material circumscribes the filter element and an adjacent region of the tobacco rod such that the tipping material extends about 3 mm to about 6 mm along the length of the tobacco rod. Typically, the tipping material is a conventional paper tipping material. The tipping material can have a porosity which can vary. For example, the tipping material can be essentially air impermeable, air permeable, or be treated (e.g., by mechanical or laser perforation techniques) so as to have a region of perforations, openings or vents thereby providing a means for providing air dilution to the cigarette. The total surface area of the perforations and the positioning of the perforations along the periphery of the cigarette can be varied in order to control the performance characteristics of the cigarette.

[0087] As used herein, the term “pressure drop” in referring to the cigarette is meant that difference between atmospheric pressure and the pressure at the extreme mouthend point of the cigarette, as measured at a given flow rate through the cigarette. Typical pressure drop values for cigarettes of the present invention are greater than about 30 mm of H2O, more frequently greater than about 50 mm of H2O at 17.5 cc/sec. of air flow rate.

[0088] Cigarettes of the present invention exhibit a desirably high resistance to draw. For example, cigarettes of this invention exhibit a pressure drop of between about 50 and about 200 mm water at 17.5 cc/sec. air flow. Typically, pressure drop values of cigarettes are measured using a Filtrona Filter Test Station (CTS Series) available from Filtrona Instruments and Automation Ltd. Cigarettes of this invention preferably exhibit resistance to draw values of about 40 to about 180, more preferably about 50 to about 150 mm H2O at 17.5 cc/sec. air flow.

[0089] In a further aspect, the present invention provides a method for modifying a performance attribute of a smoking article having a combustible material component comprising distributing ultrafine particles within the combustible material component. The ultrafine particles may be distributed in the manner described herein with reference to embodiments of smoking articles of the present invention.

[0090] While not wishing to be bound by any theory, it is believed that the ultrafine particles may alter the burning characteristics by one or more of the following mechanisms: catalyzing reactions in the burning cigarette that modify the combustion process; exploiting the ability of ultrafine particles to “carry” large quantities of selected compounds that may alter combustion (e.g., water) and/or modifying the thermal properties of a smoking articles for example the thermal conductivities. Any, or all, of these features may be utilized in a smoking article in an embodiment of the present invention.

[0091] The features and advantages of embodiments of the present invention are further illustrated by the following examples.

EXAMPLE 1

[0092] This example illustrates the use of ultrafine particles in an embodiment of the present invention to reduce the amount of carbon monoxide (CO) in the mainstream smoke of the tobacco article.

[0093] The heat source assembly from a commercially available version of the Eclipse® cigarette produced by R. J. Reynolds Tobacco Co., Winston-Salem, N.C. was utilized as a combustible material.

[0094] A first set of heat source assemblies were obtained by removing the heat source assembly from each of sixty Eclipse® cigarettes and dried at 80 C for two hours under vacuum for preparation of embodiments smoking articles of the present invention.

[0095] As a control a second set of thirty heat source assemblies were removed from another thirty Eclipse® cigarettes and left untreated.

[0096] As an additional control, a third set of thirty heat source assemblies were removed from Eclipse®D cigarettes and treated with a water solution. Approximately 10 milligrams (“mg”) of water was applied at one end of the heat source assembly. The water quickly dissipated in the peripherally located slots and centrally located hole. After application of the water, the heat source assembly was dried at 80 C, under vacuum, for approximately 12 hours (overnight).

[0097] To produce embodiments of the present invention, approximately 10 mg of a colloidal solution containing platinized titanium dioxide ultrafine particles was applied at one end of each of thirty heat source assemblies from the first set of sixty heat source assemblies. The solution quickly dissipated in the peripherally located slots and centrally located hole. After application of the solution, the heat source assembly was dried at 80 C, under vacuum, for approximately 12 hours (overnight).

[0098] In another embodiment of the present invention, approximately 20 mg of a colloidal solution containing platinized titanium dioxide ultrafine particles was applied at each end of thirty heat source assemblies from the first set of sixty heat source assemblies, for a total application of 40 milligrams. The solution quickly dissipated in the peripherally located slots and centrally located hole. After application of the solution, the heat source assembly was dried at 80 C, under vacuum, for approximately 12 hours (overnight).

[0099] The treated and untreated heat source assemblies were reincorporated into the Eclipse® cigarettes and the cigarettes were allowed to equilibrate for 2 days. The composition of the smoke produced by each cigarette under 50/30 smoking conditions, and by untreated control cigarettes, was then analyzed. The results, reported as an average for the thirty cigarettes of each type, were as shown below

1TreatmentPt—TiO2Pt—TiO2PropertyNoneWater10 mg40 mgPressure Drop,40.042.441.640.9mm H2OTPM, mg28.225.225.528.2CO, mg21.821.721.016.8Glycerin, mg10.49.89.810.4Water, mg12.610.510.812.2

[0100] As shown by the results above, use of ultrafine particles in a heat source assembly advantageously reduces the amount of carbon monoxide in the mainstream smoke of a smoking article. Further, the values indicated for pressure drop did not vary significantly indicating the application of ultrafine particles did not deform or substantially alter the physical characteristics of the smoking article.

EXAMPLE 2

[0101] This example illustrates the preparation of a ultrafine particle sol and the use of ultrafine particles in an embodiment of the present invention to reduce the amount of carbon monoxide (CO) in the mainstream smoke of the tobacco article.

[0102] Sol Creation

[0103] About 30 mg of cupric chloride (CuCl2, 2H2O) was dissolved in 1 milliliter of 1 Normal hydrochloric acid (HCl). Next, 30 mg of palladium chloride was added and the solution was stirred until the palladium chloride was completely dissolved. The resulting solution was slowly added to 10 grams of sol containing 2.2% on a weight/weight basis of titanium dioxide nanoparticles. The solution was stirred on a magnetic stirrer for about two hours at slow speed. The result was a palladium derivatized titanium dioxide (Pd—Cu—TiO2) sol. A portion of the sol was diluted four fold in water (1:3) to create a diluted palladium derivatized titanium dioxide (Pd—Cu—TiO2) sol.

[0104] Study

[0105] The heat source assembly from a version of the Eclipse® cigarette produced by R. J. Reynolds Tobacco Co., Winston-Salem, N.C. produced without any water line on the heat source assembly was utilized. The absence of a water line on the heat source assembly causes the heat source assembly not to be anchored to the fiber glass mat in the cigarette.

[0106] The heat source assembly was removed from each of 90 of the aforementioned cigarettes and dried at 80 C, under vacuum, overnight.

[0107] In an embodiment of the present invention, thirty of the heat source assemblies were wash coated with a colloidal solution containing platinized titanium dioxide ultrafine particles. The wash coating process adsorbs approximately 15 mg of sol per heat source assembly rod. The process was repeated such that a total of approximately 30 mg of sol was applied to each heat source assembly. During wash coating the solution quickly dissipated in the peripherally located slots and centrally located hole. After application of the solution, the heat source assembly was dried at 80 C, under vacuum, for approximately 2 hours.

[0108] In another embodiment of the present invention, thirty of the heat source assemblies were wash coated with the palladium derivatized titanium dioxide (Pd—Cu—TiO2) sol discussed above. The wash coating process adsorbs approximately 15 mg of sol per heat source assembly rod. The process was repeated such that a total of approximately 30 mg of sol was applied to each heat source assembly. During wash coating the solution quickly dissipated in the peripherally located slots and centrally located hole. After application of the solution, the heat source assembly was dried at 80 C, under vacuum, for approximately 2 hours.

[0109] In a further embodiment of the present invention, an additional thirty of the heat source assemblies were wash coated with the diluted palladium derivatized titanium dioxide (Pd—Cu—TiO2) sol discussed above. The wash coating process adsorbs approximately 15 mg of sol per heat source assembly rod. The process was repeated such that a total of approximately 30 mg of sol was applied to each heat source assembly. During wash coating the solution quickly dissipated in the peripherally located slots and centrally located hole. After application of the solution, the heat source assembly was dried at 80 C, under vacuum, for approximately 2 hours.

[0110] The treated heat source assemblies were reincorporated into the Eclipse® cigarettes and the cigarettes were allowed to equilibrate for 2 weeks. The composition of the smoke produced by each cigarette under 50/30 smoking conditions, and by untreated control cigarettes, was then analyzed. The results, reported as an average for each set of thirty cigarettes, were as shown below.

2TreatmentDilutedPropertyNonePt—TiO2Pd—Cu—TiO2Pd—Cu—TiO2TiO2, mg /HS00.660.600.15Pt/Pd, mg/HS00.0600.0250.006Cu, mg/HS00.000.0150.004Pressure Drop,36.236.735.036.8mm H2OAir Dilution, %24.023.823.424.0TPM, mg29.626.929.829.2CO, mg23.516.616.821.1Nicotine, mg0.810.800.900.89Glycerin, mg11.110.211.211.1Water, mg12.611.212.211.8Tar, mg16.315.016.716.5HS = Heat Source Assembly

[0111] As shown by the results above, use of ultrafine particles in a heat source assembly may advantageously reduce the amount of carbon monoxide in the mainstream smoke of a smoking article. Further, the values indicated for pressure drop did not vary significantly indicating the application of ultrafine particles did not deform or substantially alter the physical characteristics of the heat source assembly.

[0112] Although the present invention has been described with reference to particular embodiments, those of ordinary skill in the art will appreciate that the system of the present invention may be implemented in other ways and embodiments. Accordingly, the description herein should not be read as limiting the present invention as other embodiments also fall within the scope of the present invention.

Smoking article comprising ultrafine particles

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