Smoking article incorporating a conductive substrate

Abstract

The present invention provides a conductive substrate useful for Joule heating, such as in an electronic smoking article. Particularly, the invention provides a resistive heating element formed of a conductive substrate. The conductive substrate comprises an electrically conductive material and a carbonaceous additive, such as a binder material. The conductive substrate is carbonized in that it is subjected to calcining conditions to effectively reduce the carbonaceous additive to its carbon skeleton. It has been found that such carbonized substrate has surprisingly improved resistance properties in relation a substrate of the same formulation that is not carbonized. The carbonized substrate can include an aerosol precursor material. The formed resistive heating element can be included in an electronic smoking article to simultaneously provide resistive heating and aerosol formation with a single, unitary component.

1 . A resistive heating element comprising:
 a. a substrate comprising an electrically conductive material and at least one carbonaceous additive, wherein the substrate or a part thereof is carbonized; and   b. an aerosol precursor material associated with the carbonized substrate;   wherein the resistive heating element has an electrical resistance of about 15 ohms or less.   
     
     
         2 . The resistive heating element of  claim 1 , wherein the electrically conductive material comprises graphite. 
     
     
         3 . The resistive heating element of  claim 1 , wherein the electrically conductive material comprises a metal. 
     
     
         4 . The resistive heating element of  claim 1 , wherein the electrically conductive material is in a particulate form. 
     
     
         5 . The resistive heating element of  claim 1 , wherein the carbonaceous additive comprises tobacco or a tobacco derivative. 
     
     
         6 . The resistive heating element of  claim 1 , wherein the carbonaceous additive comprises milled carbon. 
     
     
         7 . The resistive heating element of  claim 1 , wherein the carbonaceous additive comprises a binder. 
     
     
         8 . The resistive heating element of  claim 7 , wherein the binder is a polysaccharide or a derivative thereof. 
     
     
         9 . The resistive heating element of  claim 8 , wherein the binder is a gum. 
     
     
         10 . The resistive heating element of  claim 8 , wherein the binder is a cellulose or cellulose derivative. 
     
     
         11 . The resistive heating element of  claim 7 , wherein the binder is selected from the group consisting of guar gum, carboxymethyl cellulose, inorganic materials, and combinations thereof. 
     
     
         12 . The resistive heating element of  claim 1 , wherein the carbonized substrate has a porosity of about 10% or greater. 
     
     
         13 . The resistive heating element of  claim 1 , wherein the weight percent of carbon in the carbonized substrate relative to the total weight of the carbonized substrate exceeds the weight percent of carbon in the substrate when it is not carbonized relative to the total weight of the substrate when it is not carbonized. 
     
     
         14 . The resistive heating element of  claim 13 , wherein the weight percent of carbon in the carbonized substrate exceeds the weight percent of carbon in the non-carbonized substrate by about 10% or greater. 
     
     
         15 . The resistive heating element of  claim 1 , wherein the aerosol precursor material comprises a polyhydric alcohol. 
     
     
         16 . The resistive heating element of  claim 15 , wherein the polyhydric alcohol is selected from the group consisting of glycerin, propylene glycol, and combinations thereof. 
     
     
         17 . The resistive heating element of  claim 1 , wherein the aerosol precursor material comprises an inhalable substance. 
     
     
         18 . The resistive heating element of  claim 17 , wherein the inhalable substance comprises a medicament. 
     
     
         19 . The resistive heating element of  claim 17 , wherein the inhalable substance comprises nicotine. 
     
     
         20 . The resistive heating element of  claim 17 , wherein the inhalable substance comprises a tobacco component or a tobacco-derived material. 
     
     
         21 . The resistive heating element of  claim 1 , wherein the aerosol precursor material is in a slurry with tobacco, a tobacco component, or a tobacco-derived material. 
     
     
         22 . The resistive heating element of  claim 1 , wherein the aerosol precursor material comprises a flavorant. 
     
     
         23 . The resistive heating element of  claim 1 , wherein the aerosol precursor material is coated on, adsorbed by, or absorbed in the substrate or a part thereof. 
     
     
         24 . The resistive heating element of  claim 1 , wherein the resistive heating element has an electrical resistance of about 8 ohms or less. 
     
     
         25 . The resistive heating element of  claim 1 , wherein the resistive heating element has an electrical resistance of about 0.1 ohms to about 8 ohms. 
     
     
         26 . The resistive heating element of  claim 1 , wherein the resistive heating element comprises:
 a. a substrate comprising an electrically conductive material selected from the group consisting of graphite, metal particles, and combinations thereof; milled carbon; tobacco; and at least one polysaccharide; wherein the substrate is carbonized; and   b. a polyhydric alcohol aerosol precursor material associated with the carbonized substrate;   wherein the resistive heating element has an electrical resistance of about 15 ohms or less.   
     
     
         27 . The resistive heating element of  claim 1 , wherein the resistive heating element comprises:
 a. a substrate comprising an electrically conductive material selected from the group consisting of graphite, metal particles, and combinations thereof; and at least one polysaccharide; wherein the substrate is carbonized; and   b. an aerosol precursor material associated with the carbonized substrate, the aerosol precursor material comprising a polyhydric alcohol and an inhalable substance;   wherein the resistive heating element has an electrical resistance of about 15 ohms or less.   
     
     
         28 . The resistive heating element of  claim 1 , wherein the heating element is elongated and has a length of about 5 mm to about 40 mm. 
     
     
         29 . The resistive heating element of  claim 28 , wherein the heating element is substantially rod shaped. 
     
     
         30 . The resistive heating element of  claim 29 , wherein the heating element has a mean diameter of about 0.5 mm to about 5 mm. 
     
     
         31 . The resistive heating element of  claim 1 , wherein the heating element is elongated and has a non-uniform cross-sectional geometry. 
     
     
         32 . The resistive heating element of  claim 1 , wherein the electrically conductive material is in the form of a core that is substantially surrounded by the at least one carbonaceous additive. 
     
     
         33 . The resistive heating element of  claim 1 , wherein the electrically conductive material is in the form of a sheath that substantially surrounds a core comprising the at least one carbonaceous additive. 
     
     
         34 . The resistive heating element of  claim 1 , wherein the substrate is an extrudate. 
     
     
         35 . The resistive heating element of  claim 1 , wherein the substrate is in a non-extruded form. 
     
     
         36 . The resistive heating element of  claim 35 , wherein the substrate is pelletized. 
     
     
         37 . The resistive heating element of  claim 35 , wherein the substrate is in the form of a sheet. 
     
     
         38 . The resistive heating element of  claim 37 , wherein the substrate is in the form of a rolled sheet. 
     
     
         39 . The resistive heating element of  claim 1 , wherein the substrate is substantially chip-shaped in that it is flattened with a defined length, width, and thickness. 
     
     
         40 . The resistive heating element of  claim 1 , wherein the substrate is substantially disc-shaped. 
     
     
         41 . The resistive heating element of  claim 1 , further comprising a substrate support frame. 
     
     
         42 . The resistive heating element of  claim 41 , wherein the substrate is substantially suspended within the support frame. 
     
     
         43 . The resistive heating element of  claim 41 , wherein the substrate is deposited on the support frame. 
     
     
         44 . The resistive heating element of  claim 41 , wherein the substrate support frame has a cross-section that includes a linear portion. 
     
     
         45 . The resistive heating element of  claim 41 , wherein the support frame includes a component that forms an electrical connection with a power source. 
     
     
         46 . A smoking article comprising a resistive heating element of  claim 1  in electrical connection with an electrical power source. 
     
     
         47 . The smoking article of  claim 46 , wherein the resistive heating element and the electrical power source are removably connected. 
     
     
         48 . The smoking article of  claim 46 , wherein the electrical power source is selected from the group consisting of a battery, a capacitor, and combinations thereof. 
     
     
         49 . The smoking article of  claim 46 , wherein the article comprises a control component that actuates current flow from the electrical power source to the resistive heating element. 
     
     
         50 . The smoking article of  claim 49 , wherein the control component comprises a puff-actuated sensor. 
     
     
         51 . The smoking article of  claim 49 , wherein the control component comprises a pushbutton. 
     
     
         52 . The smoking article of  claim 49 , wherein the control component comprises a capacitive sensor. 
     
     
         53 . The smoking article of  claim 46 , wherein the article comprises a component that regulates a previously initiated current flow from the electrical power source to the resistive heating element. 
     
     
         54 . The smoking article of  claim 53 , wherein the current regulating component is a time-based component. 
     
     
         55 . The smoking article of  claim 53 , wherein the current regulating component stops current to the resistive heating element once a defined temperature has been achieved. 
     
     
         56 . The smoking article of  claim 53 , wherein the current regulating component cycles the current to the resistive heating element off and on once a defined temperature has been achieved so as to maintain the defined temperature for a defined period of time. 
     
     
         57 . The smoking article of  claim 53 , wherein the current regulating component cycles the current to the resistive heating element off and on to maintain a first temperature that is below an aerosol precursor temperature and allows an increased current flow in response to a current actuation control component so as to achieve a second temperature that is greater than the first temperature and that is an aerosol precursor temperature. 
     
     
         58 . The smoking article of  claim 57 , wherein the first temperature is about 50° C. to about 110° C. 
     
     
         59 . The smoking article of  claim 57 , wherein the second temperature is about 120° C. to about 300° C. 
     
     
         60 . The smoking article of  claim 46 , wherein the article comprises a plurality of control components. 
     
     
         61 . The smoking article of  claim 46 , wherein the smoking article comprises a first unit that is engagable and disengagable with a second unit, the first unit comprising the resistive heating element, and the second unit comprising the electrical power source. 
     
     
         62 . The smoking article of  claim 61 , wherein the second unit further comprises one or more control components that actuate or regulate current flow from the electrical power source. 
     
     
         63 . The smoking article of  claim 61 , wherein the first unit comprises a distal end that engages the second unit and an opposing, proximate end that includes a mouthpiece with an opening at a proximate end thereof. 
     
     
         64 . The smoking article of  claim 63 , wherein the first unit comprises an air flow path opening into the mouthpiece of the first unit, said air flow path providing for passage of aerosol formed from the resistive heating element into the mouthpiece. 
     
     
         65 . The smoking article of  claim 61 , wherein the first unit is disposable. 
     
     
         66 . The smoking article of  claim 46 , wherein the article comprises a shell with a removable mouthend. 
     
     
         67 . The smoking article of  claim 66 , wherein the resistive heating element includes a substrate support frame. 
     
     
         68 . A kit comprising:
 a case;   one or more disposable units for use with a reusable smoking article, the disposable unit comprising cartridge body with a distal end configured to engage a component of a reusable smoking article and an opposing, proximate end that includes a mouthpiece with an opening at a proximate end thereof, each of the one or more disposable units comprising a resistive heating element according to  claim 1  disposed within the cartridge body; and   optionally one or more components selected from the group consisting of a reusable control unit, a battery, and a charging component.   
     
     
         69 . The kit of  claim 68 , wherein the reusable control unit comprises: a control housing including an engaging end for engaging the distal end of the cartridge body of the disposable unit; an electrical power source disposed within the control housing; and one or more control components disposed within the control housing, the one or more control components being configured to actuate or regulate current flow from the electrical power source. 
     
     
         70 . A method of preparing a resistive heating element, the method comprising:
 a. combining an electrically conductive material with at least one carbonaceous additive to form an intermediate substrate;   b. heating the intermediate substrate for a defined period of time at a temperature of about 200° C. or greater to form a carbonized substrate; and   c. associating an aerosol precursor material with the carbonized substrate to form the resistive heating element.   
     
     
         71 . The method of  claim 60 , wherein said combining step comprises mixing for a time of about 5 minutes or greater. 
     
     
         72 . The method of  claim 60 , wherein said mixing step comprising adding a liquid such that the intermediate substrate has a moisture content of about 15% or greater. 
     
     
         73 . The method of  claim 60 , further comprising, after said combining step, forming the intermediate substrate into a defined shape. 
     
     
         74 . The method of  claim 73 , wherein said forming step comprises extruding the intermediate substrate to form an extrudate. 
     
     
         75 . The method of  claim 73 , comprising forming the intermediate substrate into an elongated form. 
     
     
         76 . The method of  claim 75 , wherein the elongated form has a length of about 2.5 mm to about 60 mm. 
     
     
         77 . The method of  claim 73 , comprising forming the intermediate substrate into a form that is substantially cylindrical. 
     
     
         78 . The method of  claim 77 , wherein the substantially cylindrical intermediate substrate has a uniform, mean diameter of about 1 mm to about 15 mm. 
     
     
         79 . The method of  claim 73 , comprising forming the intermediate substrate into a form that is elongated and has a non-uniform cross-sectional geometry. 
     
     
         80 . The method of  claim 73 , comprising forming the substrate into pellets. 
     
     
         81 . The method of  claim 73 , comprising forming the substrate as a sheet. 
     
     
         82 . The method of  claim 81 , comprising rolling the formed sheet. 
     
     
         83 . The method of  claim 70 , wherein said combining step comprises providing the electrically conductive material in the form of a core that is substantially surrounded by the at least one carbonaceous additive. 
     
     
         84 . The method of  claim 70 , wherein said combining step comprises providing the electrically conductive material in the form of a sheath that substantially surrounds a core comprising the at least one carbonaceous additive. 
     
     
         85 . The method of  claim 70 , wherein the electrically conductive material comprises graphite. 
     
     
         86 . The method of  claim 70 , wherein the electrically conductive material comprises a metal. 
     
     
         87 . The method of  claim 70 , wherein the electrically conductive material is in a particulate form. 
     
     
         88 . The method of  claim 70 , wherein the carbonaceous additive comprises tobacco or a tobacco derivative. 
     
     
         89 . The method of  claim 70 , wherein the carbonaceous additive comprises milled carbon. 
     
     
         90 . The method of  claim 70 , wherein the carbonaceous additive comprises a binder. 
     
     
         91 . The method of  claim 90 , wherein the binder is a polysaccharide or a derivative thereof. 
     
     
         92 . The method of  claim 91 , wherein the binder is a gum. 
     
     
         93 . The method of  claim 91 , wherein the binder is a cellulose or cellulose derivative. 
     
     
         94 . The method of  claim 90 , wherein the binder is selected from the group consisting of guar gum, carboxymethyl cellulose, and combinations thereof. 
     
     
         95 . The method of  claim 70 , wherein the carbonized substrate has a porosity of about 10% or greater. 
     
     
         96 . The method of  claim 70 , wherein the weight percent of carbon in the carbonized substrate relative to the total weight of the carbonized substrate exceeds the weight percent of carbon in the intermediate substrate relative to the total weight of the intermediate substrate. 
     
     
         97 . The method of  claim 96 , wherein the weight percent of carbon in the carbonized substrate exceeds the weight percent of carbon in the non-carbonized substrate by about 10% or greater. 
     
     
         98 . The method of  claim 70 , wherein the aerosol precursor material comprises a polyhydric alcohol. 
     
     
         99 . The method of  claim 98 , wherein the polyhydric alcohol is selected from the group consisting of glycerin, propylene glycol, and combinations thereof. 
     
     
         100 . The method of  claim 70 , wherein the aerosol precursor material comprises an inhalable substance. 
     
     
         101 . The method of  claim 100 , wherein the inhalable substance comprises a medicament. 
     
     
         102 . The method of  claim 100 , wherein the inhalable substance comprises nicotine. 
     
     
         103 . The method of  claim 100 , wherein the inhalable substance comprise a tobacco component or a tobacco-derived material. 
     
     
         104 . The method of  claim 70 , wherein the aerosol precursor material is in a slurry with tobacco, a tobacco component, or a tobacco-derived material. 
     
     
         105 . The method of  claim 70 , wherein the aerosol precursor material comprises a flavorant. 
     
     
         106 . The method of  claim 70 , wherein said heating step is carried out in an inert atmosphere. 
     
     
         107 . The method of  claim 106 , wherein said heating step is carried out in a nitrogen atmosphere. 
     
     
         108 . The method of  claim 70 , wherein said associating step comprises coating, adsorbing, or absorbing the aerosol precursor material on or in the carbonized substrate. 
     
     
         109 . The method of  claim 70 , wherein the resistive heating element has an electrical resistance of about 25 ohms or less. 
     
     
         110 . The method of  claim 109 , wherein the resistive heating element has an electrical resistance of about 10 ohms or less. 
     
     
         111 . The method of  claim 109 , wherein the resistive heating element has an electrical resistance of about 0.1 ohms to about 10 ohms. 
     
     
         112 . The method of  claim 70 , further comprising attaching the resistive heating element to a support frame. 
     
     
         113 . The method of  claim 112 , wherein the resistive heating element is substantially suspended within the support frame. 
     
     
         114 . The method of  claim 112 , wherein the resistive heating element is deposited on a surface of the support frame. 
     
     
         115 . A method of forming an aerosol, the method comprising placing a resistive heating element according to  claim 1  into electrical connection with an electrical power source. 
     
     
         116 . The method of  claim 115 , wherein the electrical power source is an electronic smoking article.