CA2106322A1 - Composite fuel element for smoking articles - Google Patents

Abstract

COMPOSITE FUEL ELEMENT FOR SMOKING ARTICLES

ABSTRACT OF THE DISCLOSURE
The present invention is directed to improvements in carbonaceous fuel elements wherein (a) the fuel elements are provided with a composite support member which assists in retaining the fuel element within the cigarette structure during smoking, and (b) the fuel elements burn at a lower average temperature than previously known carbonaceous fuel elements. In one preferred embodiment of the present invention, the fuel element comprises at least two different materials contiguous throughout the length thereof, and including one material which burns, and another material which preferably does not burn, or burns more slowly than the burnable material. The non-burning, or substantially non-burning material is advantageously a heat exchange material such as graphite. In preferred embodiments, the nonburning support or retaining member extends beyond the periphery of the burnable material such that it interacts with the insulating jacket which surrounds the fuel element, locking the same in place, particularly during smoking.

Description

" 21 ~22 COMPOSiTE FUEL ELEMENT FOP~ SMOKING ARTlt::LES

FIELD OF THE II~IVENTION

The present invention is directed to improvements in smoking articles, particularly smokirlg articies employing tobacco. Cigarettes, ci~ars and pipes are popular smoking articles which use tobacco in various forms. Many products have ~een proposed as improvements upon, or alternatives to, the various popular smoking artioles. For exampls, numerous refer~nees have proposed articles which generate a flavorad vapor and/or a visible aerosol~
Most of such ar~icles have employed a oombustible fuel source to provide an aerosoi and/or to heat an aerosol forming mat~rial. See, for example, the background art cited in lJ.S. Patent No. 4,714,û82 to Banerjee e~ al.

The present invention relates to smoking articles su~h a~ cigarettes, and in particular to those smoking articles having a short fuel elsment and a physically separate acrosol ~eneratin~ means. Smoking articles of this type, as well as materials, methods and/or apparatus usaful therein and/or for preparing them, are describsd in thc following U.S. Pat. Nos. 4,7~8,151 to Shelar; 4,714,082 to Banerjee et al.; 4,732,168 to Resce; 4,756,318 ~o Clearman et al.; 4,7B2,644 ~o Haarer et al.; 4,793,365 ~o Sensabaugh et al.;
4,802,568 to Haarer et al.; 4,827,950 to Banerjee et al.; 4,870,748 to Hensgen et al., 4,881,556 to Clearman et al.; 4,893,637 to Hancock et ai.; 4,893,639 to White; 4,gO3,714 to Barnes et al.; 4,917,128 to Clearman et al.; 4,~28,714 to Shannon; 4,938,238 to Hancock et al., 4,989,619 to Clearman et al., 5,027,837 2~6322 to Clearman et al., 5,038,802 to White et al., 5,042,509 to Banerjee et al., 5,052,413 to Baker st al., 5,060,666 to Clearman et al., 6,065,776 to Lawson et al., 5,067,499 to Banerjee et al., 6,076,292 to Sensabaugh et al., 5,076,297 to Farrier et al., 5,088,507 to Baker et al., 5,09g,861 to Clearman et al., 5,1û1,839 to Jakob et al., 5,1~,831 to Banerjee et al., and 5,1û~,837 to Barnes et al., aswell as in the monograph en~itled Chemical and Biol_ i~S udles of New Ci~arette Proto~pes That Heat Instead of Burn Tobacco, R.J. Reynolds Tobacco Company, 1988 (hereinafter "RJR Monograph"). These smoking articles are capable of providing the smoker with the pleasures of smoking 10 (e.g., smoking taste, feel, satisfaction, and the like). Such smoking articles typically provide low yields of visible sidestream smoke as well as low yields of FTC tar when smoked.

The smoking articles describ~d in the aforesaid patents and/or publications generally employ a cornbustible fuel element for heat generation 1~ and an aerosol 3enerating means, posltioned physically separate from, and typically in a heat exchange reiationship with the fuel element. Many of these aerosol generating means employ a substrate or carrier for one or more aerosol forming materials, e.g., polyhydric alcohols, suoh as glycerin. The aerosol forming materials are volatilized by the heat from the burning fuel 20 element and upon cooling form an aerosol. Norrnally, the fuel elements of such smoking articles are circurnscribed by an insulating jacket.

The fuel elements employed in the above-described smoking articles burn to produce combustion products such as carbon dioxide, carbon monoxide, water and trace quantities of other compounds.' One known 25 method forreducing the amount of carbon monoxide produced by the burning of a fuel element is to reduce the combustion temperature of that fuel elemen~. Redueing the combustion temperature reduces the calories generated, thereby reducing the heat that must be dissipated during smoking.

2:~6322 This assists in preventing overheating of the smoking article.

SUMUIARY OF THE INVENTION

The pr~sent invention is directed to improvements in carbonaceous fuel eiements wherein such fuel elcments comprise a composite structure, a 5 portion o~ which Gomprises a burnable or combustible carbonaceous material, and a portion of which comprises at least one support member which either does not burn, or which burns mors slowly than the combu~ible portion (i.e., a non-burnable portion), thereby remaining inta~t during smoking and assisting in retaining the fuel element within the cigarette structure during 1 0 smoking.
.

In preferred fuel elements of the present invention, the composite fuel element cornprises at least ~NO different materials, each of which is preferablycontiguous to the other throughout the leng~h of the fuel element. First, and primarily, a carbonaceous material whioh burns, and second, ~ material which 15 does not burn, or burns very little or very slowly, particularly when compared to the burning material, and which provides a supporting structure as the remainder of the fuel element is otherwise consumed durin~ smoking. The material in the fuel ~Isment of ~he present invention which does no~ burn completely during the life of the smoking article is hereafter referred to as 20 "non-burning material."

The burnabl~ carbonaceous material useful herein ~an be any carbonaceous composition capable of sustained bum during smolder. The patents described above discloses numerous combustible carbonaceous compositions which can be employed hersin. As discussed therein, these 25 compositions can contain optional ffllers, cxtenders, additiv2s (e.g., tobacco) 210~322 and binders, if desired.

The non-burnin~ material includsd in the fuel element pre~rably has good heat exchange and heat conductive properties, although other non-burning materials which do not exhibit such good hea~ exchange or 5 conductive properties may also be used herein. Thus, preferred non burning materials includ~ extruded graphite or other non-burnin~ carbon containing compositions, metal ribbons, foils, or the like. Exemplary non-burning materials with poor heat exchan~e and/or conductive properties include inorganic compounds such as calcium carbonats, cer~mics and the like.
10 Especially preferred non-burning materials include non-burning carbons such as extruded graphite, graphite foils, and m~tal ribbons, such as stainless steel, aluminum and copper. The currently most preferred non-burning materials are non-burning carbons such as graphite, which can easily be produced in an integral structure with the burnable carbonaceous material.

In most embodiments of the present invention, ~he burning and non-burning materials which comprise the fuel elements, form separate longitudinal components of the fuel element. Preferably the non-burning component forms a section which traverses the length of the fuel element, i.e., from end ts end. Pre~rably the nonburning component(s) extend slightly 20 beyond ~he periphery of the burnable carbonaceous material, thereby providing means for locking the fuel slement in any jacket which surrounds it in a cigarette. Typically, the non-burning material is located centrally in the fuel element, dividing the burnable material equally into tvvo parts. if desired, more than one sec$ion of non~burning material could be u~ed in the fuel 2~ element, e.g., providing two or more sections of non-burning material. As thecarbonaceous component of the fuel element burns, the non-burning portion does not, thereby maintaining its structure.

21063~2 The fuel elements of the present invention provide hNo main beneffts:
retention of the burning fuel element within the cigarette throughout smoking, and reduced carbon monoxicle production. in accordance with the present invention, the structure of the non-burnin~ portion of the fuel element remains 5 in contact with the insulating material during smoking. As a result, the burning carbonaceous componsnt is r~ained within the insulating material throughout the burning period.

The reduction in carbon monoxide oan be achieved in at least two ways. Preferably, the non-burning portion conducts some heat out of the 10 burning portion of the fuel elements of the present invention, so ~hat ~hey tend to burn at a lower average temperature than previously known carbonaceous fuel elements. The reduced temperature of the burning fuel elements provides a reduction in carbon monoxide output. While the fuel elements of ~he present invention burn at a cooler tempera~ure than previously known fuel 15 elements, they do not go out during smolder, and they still provide sufficient heat energy to generate aerosol over the 10-15 puff life of the cigarettes in which they are employed.

Moreover, the lack of necessity of maintaining an unburned plug of burnable fuel in order to retain ~he fuel element in the cigaratte means that fuel 20 elements can now be designed such that only the a nount of combustible material necessary to provicle the desired number of puffs of aerosol needs ~o be included therein. Thus, the fuel composition can be formulated to provide only the amount of energy needed to drive the cigarette. No excess combustible material is needed to retain the fuel element ~Ivithin the smoking 25 article. Thus the size and mass of the fuel element can be reduced, and ~he smaller tha amount of carbonaceous ma~erial bumed, the less carbon monoxide is genera~ed 2~063~2 The ~uel elamant may be formed by eoextruding a non-burning material and a burning material. The burnable carborlaceous component may be extruded onto the surFace of the non-burnin~ material, preferably on both sides thereof, or the non-burning material can be extruded on at least one 5 side, preferably both sides, o~ the burnable carbonaceous rnaterial.

Alternatively, the non-burning compon~n~ may be in the form of a strip or ribbon which is passed through an ex~ruder and the carbonaceous material is extruded onto ~he non-burning material. If a ribbon is used, openings may be provided through the ribbon so that, as the burnable carbonaceous 10 material is ex~ruded, it can flow through the openin~s to form an integral link between the carbonaceous sections on opposite sides of the ribbon. If the ribbon is an exceptionally good conduc~ing material, such as a graphite or metal foil, the openings help to reduca the heat exchange area batween the carbonaceous material and the non-burning ma$erial so that the lleat transfer 15 to the non-burning material is inadequate to cause extinguishment of the burnable portion of the fuel element, particularly during smolder periods.

By using a non-burning component in contact with the insulating material, ~he fuel element is maintained in the cigarette structura without the unburned portion of fuel which previously was retained by the insulating 20 material. This permits the reduction in size of the ~uel elerrlsnt, so that only the appropriate amount of burnable carbonaceous material need be used to generate the desired amount of aerosol. Reduction in the amount of carbon burned also reduces the amount of heat generated by ~he fuel elemAn~, which aiso reduces the amount of carbon monoxide produced dt~ring burning.

2~ The non-burning component of the fuel elernent may be incorporated into the combustible fuel element by any means available to the skilled a~isan.
One preferred incorporation route is the longitudinal coex~rusion of a non-2~322 burnin~ or subs~antially non-burning carbonaceous mass, e.g., carbon or graphite, with the burnable carbonaceous fuel composition. Lon~itudinal coextrusion allows the formation of intricate fuel element designs, each of which has desirable ligh~ing and/or burning properties. In especially preferred 5 embodiments, at least a portion of the coextrudad non-burnable material extends beyond the periphery o~ the fuel element, thereby allowing the exposed material to lock into any insulating jacket or other oven~rap employed around thc periphery of the ~uel element.

An~ther preferred roLne for the incorporation of a non-burning heat 10 exchange rnaterial into the extruded fuel element is the so-called "ribbon-pull"
method. In this method, as the fuel composition is being extruded, the extrudate pulls a ribbon of non-burning material along with it. The extrudate becomes attached to the non-burning ribbon by bonding thereto during the drying process. In sspecially pre~erred ernbodiments, at least a portion of the 15 ribbon extends beyond the periphery of the fuel element, thereby allowing theexposed ribbon portion(s) to lock into any insulating jacket or other overwrap employed around the periphery of the fuel el0ment.

As used herein, the term "carbonaceous" means comprising primarily carbon.

All percentages given herein are by weight, and all weight psrcentages given herein are based on the final composition weights, unless othelwise noted.

E~RIEF DESCRIPTI59N QF THE DRAWIN~;S

Fig. 1 illus~rates in s~ctional view, one embodiment of a cigarette 25 incorporating a ~el element prepared in accordance with the present 210~3~2 invention.

Fig. 1A is an end view of the ci~arette shown in Fig. 1.

Figs. 2 - 4 iilustrate the end view of ~hree pref~rred fuel element designs prepared according to ~his invention, showiny some of the patterns availabls under the teachin~s of this invention.

Figures 5 - 7 illustrate some of the various physical shapes useful herein for the ribbon-like noncombustibla retaining member in the fuel element.

Figure 8 illustrates one preferred proeess for preparing ~uel elements of 10 the'present invention, the "ribbon pull" method.
Figure 9 illustrates another preferred process for preparing fuel ,?lements of the present invention, particularly the iongitudinal coextrusion process.

Fig. 9A is a schematic sectional drawing depic~ing a section through 15 the devic~ of Fi~. 9 along line 9A, 9A' Figure 10 iliustrates a cross section of another preferred structure for a fuel element of tha present invention.

Figure 11 illustrates, partially in section, the s~ructure of an extrusion die for use in a coextrusion process for manufacturing the fuel' elernent illustrated 20 in Figure 10.

21063~2 g DETAILED DFSCRIPTION OF PREFERRED EMBODln~ENTS

As described above, the present invention is particularly directed to improvements in carbonaceous fuel elements useful in smoking articles.
Figures 1 and 1A illustrate a preferred erT1bodimant of a cigarette employing a fuel element of the present invention.

As illustrated in Fig. 1 and more particularly in Fig. 1A, th~ fuel element 10 comprises two distinct portions, the combustibte carbonaceous material 9, which includes a number of peripheral grooves 11 running aiong its longitudinal axis, and the non-burning heat exchange material 7 whieh runs 10 longitudinally from end to end, and extends slightly beyond the periphery of the combustible segments 9 oF the fuel element 10. As illustrated, the noncombustible component of the fuel element 7 may also include one or more peripheral grooves 8, if desired~

An insulating jacket surrounds the periphery of the fuel element and in 15 the illustrated embodiment comprises alternating layers of glass fibers and tobacco paper, arranged as concentric rin~s eman~ting outwardly from the fuel element in the following order; (a) ~lass fiber mat 12; (bl tobacco paper 15; and (c) glass fiber mat 17; and an outer paper wrapper 13. As illustrated, ~he noncombus$ible heat exchange materiat 7 extends into the insulating 20 jacket, thereby providing a permanent means for retaining the fuel elemant therein. The outer paper wrapper 13 may comprise one layer or may be prepared trom a plurality of separate layers, each having different porosity andash stability characteristics.

Situated behind and spaced slightly apart from the insulated fuel 25 element 1û, is an aerosol generating means, which includes substrate 14. In this embodiment, the substrate is prefarably a heat-stabilized paper, treated 21~6322 with ona or more hydrated salts, ancl which further contains one or mo~
aarosol formin~ ma~erials and/or flavorants. The substrate 14 is overwrapped with a paper overwrap 24 which advanta~3eously is trea~sd (e.g., coated) to prevent migration of the aerosol forming rnaterials.

Spaced longitudinally behind, and, prefarably spaced slightly apart from substrate 14, is a segment of tobacco paper 28. This tobacco paper generally provides tobacco flavors to the aerosol ernitted from ~he aerosol generating means. Tobacco segment 28 ean be omitted if desired and a void space substituted therefor. Paper overwrap 25 combines the aerosol generating msans withthe~obacco papersegment. This oye~Nrap may also be treated to prevent migration of ths aerosol forming materiais.

Circumscribing the insulated fuel slernent, at a point about 2 to ~ mm from the li~htin~ end of the cigarett~, and combining it with the combined substratettobacco paper segment to form a front end assembly is a non-burning or foil-backed (e.g., aluminum or other metal) paper wrapper 29.
Wrapper 29 is preferably a non-wicking n aterial which prevents transfer o~ the aerosoi forming materials on the subs~rate 14 to the fuel element 10, the insulating jacket, and/or from stainin~ of the other components of the front end assembiy. This wrapper also minimizes or prevents peripheral air (i.e., radial ~r) from flowing to the portion o~ the fuel element disposed longitudinally bchind its ~orward edge, thereby causing o~ygen deprivation and preventing excessive combustion.

Positioned at the mouth end of the cigarette is a twb part mouthend piece comprisin~ ~i) a rod or roll of tobacco 20, such as tobacco cut flller 2 and (ii~ a low-efficiancy fllter element 22. A tipping paper :~1 is used to join- ~ha rnouthend pi~ce to the frontend assembly.

~0~322 In another preferred ernbodiment, the jacketed fuel element.is shortened so that only the requirsd amount of burnable earbonaceous material is provided for the genaration of a predetarmined number of puffs. In such an embodiment, the outer wrapper 2.9 preferably extends to the forward 5 end of the jacke~ed fuel alement. Wrapper 29 is thus designed wi~h an appropriate porosity to permi~ the carbonaceous fuel to obtain the ~ir needed for burning of all of the carbonaceous material while having sufficient cohesiveness after burning to remain intact, to hold the jaoketed fuel element on the ci~arette. Such papers are described in U.S. Patent No. 4,938,238.

Figures 2 - 4 illustrate various fuel element front end configurations, wherein the non-burning retainer ma~erial is represented by reference numeral 7. Optional peripheral slots in the non-burniny material are signified by referenee nurneral 8. As in Fig. 1A, the cornbustible portions of the fuel element are identified as reference numeral 9, and the optional peripheral slots15 or passageways shown therein are signi~ed by ref~rence nurneral 11.

Figures 5 - 7 illustrate some of the various physical shapes useful herein for the ribbon-like non-burning ret~ning member in the fuei element. In Fig. 5, the non-burning ribbon ma~erial has a waving (or undulating) configuration. in Fig. 6, lhs ribbon is provided with a saw tooth configuration.20 in Fig. 7, a flat, straight ribbon is illustrated. In each of Figs. 5 - 7, optional holes 5 are shown. These holes are providad to allow the combustible carbonaceous fuel oomposition to pass through during the extrusion process in which the fuel element is formed, thereby locking the non~burning ribbon material in the burnable portion of the fuel element.

The fuel elements employed herein should meet three criteria; (1) they should be easy to igni~e, (2) they should supply enough heat to produce aerosol for about 5-15, preferably abou~ 8~12 puffs; anei (3) they should not 210~3~2 contribute off-taste or unpleasant aromas to the cigarette. The combustible portion of ths fuel elements of the present invention eypically cornprises carbon and a binder, or carbon, tobacco and a binder, but other combustible carbonaceous compositions may be used.

The praferred fuel elements of the present invention are designed to provide only the heat required to generate a desired amount of aerosol Preferably there is no waste of fuel or waste of heat generated during ~he burning of the fueL In addi~ion, there is no exoess fuel which could be used to overheat the substrate or other compone~s of the cigarette. The fuel elements of the pres2nt inYenuon thus providc an ideal energy source for the cigarettes in which they are employed. In the cigarettes of the present invention, the fuel element is designed to genera~e the calories required for aerosol generation, with minimal heat loss to other components or to the atmosphere.

The inclusion of a non-burning retairling means in ~he fu~l element provides a means for reducing the amount o~ carbon required to be burned.
This is particularly advantageous in that only the amount of combustibie fuel necessary to form aerosol for the desired number of puffs need be used.
Another advantage of using only the amount of combustible carbon needed to form the desired amount of aerosol is tha~ as the amoun~ of burned carbon is reduced, and the carbon mono)dde generated during combustion is also reduced.

The following table illustrates the beneficial reductioh in carbon monoxide levels, as determined for fuel elements o~ the present invention verses a previously employed fuel element design.

210~22 TABLIE

DATA REFERENCE FIG. 2 FIG. 3 FIG. 10 FUEL FUEL~ FUEL FUEL
Carbon Burned (mg) 86 88 58 78 CO~ (mg) 87 82 63 68 CO (mg) 22 16 12 17 Calories 207 190 146 160 CO/cal. û.105 0.082 0.080 0.105 Calories to substrate 27.4 21.8 23.2 --ln the Table, the "Reference Fuel" is substantially that fuel element described herein in Raference Example 1. The "Fig. 2 Fuel" fuel is described herein in Exarnple 2. The "Fig. 3 Fuzl" fuel is described herein in Example 3.
15 The "Fig. 10 Fuel" fuel is described herein in Example 4. The data r~flacted in the Table were all obtained undsr machine srnokin~ ~onditions of 50 cc puff volume of 2 ~econds duration, separated by 28 seeorld~ o~ smolder time (hereinaf~er 50/39 smoking conditions), f~r a ~otal of 20 puffs.

The density of the burnable carbonaceous portion of the preferred fuel 20 elements is generally greater than about 0.5 g/cc, preferably greater than about 0.7 ~/cc and most preferably greater than about 1 g/cc, but typically does not exceed 2 g/cc.

When a coextrudsd por~ion is employed as ~he non-bumable haat exchange portion of the fuel element, the most important factor is typically the thickness of the material used, as well as its abili~y to conduct heat.
Coextruded non-burning segments having a thickness of from about 0.02 inch to about 0.04 inch have proven very effective as heat exchangers herein.

The overall length of ths fuel element, prior to burning, i3 generally less than about 20 mrn, o~tan less than about 15 rnm, and is typically less than 12 mm. The overall outside diameter of the fuel element is typically less than about 8 mm, advantageously less than about 6 mm and is typically about 4.5 mm.

As described above, at least two processas are currently preferred for the generation of fuel elements containing a non-burnable heat exchange material - the "ribbon pull" method and coextrusion. In the first method, thA
ribbon pull, a ribbon-like me~al or m~tal-like material is fed to an extruder, and is coa~ed therein with an e~ruded carbonaceous fuel composition. The resultin~ continuous rod having a ribbon in the center is then dried and cut to iength as desired. The "ribbon pull" method îs illustrated in Figure 8.

The matal or metal-like ribbon can be made from any convenient material, e.g., a thin metal f~il, such as stainless steel, aluminum, copper, and the like. Suitable me~al-like ribbon materials are materials which have a high heat conduction capaci~y, such as Grafoil, available from I Jnion Carbide Corp.
The foil material can have any desired shapa or configura~ion. See Figures 5-7. Typically, the foil has a ~hickness of from about 0.002 to about 0.02, preferably from about 0.005 to abo~n 0.û15, and most preferably about 0.0~0 inches. The width of the foil is typically from about 0.15 t~ about 0.22, preferably from about û.16 to about 0.2, and most preferably about 0.18 inches. If desired, holes, about û.04 to about 0.1, preferably about 0.06 to about 0.09, most preferably about 0.07 inches in diameter are provided in the foil. These holes are typically provided every 1/4 inch, preferably every 3/16 21~32~

inch, most preferably every 1/8 inch, so that the carbonaceous extrudate can lock the ribbon in place.

As illustrated in Fig. 8, a non-burnabie ribbon material 1 is fed into the back of feed tube 2 and through ~he back ex~rusion die 3. Here the ribbon 5 (e.g., graphite foil) i~ pulled through the burnable carbonaceous fuel composition that is fed into the die asssmbly through a side port in the die holdin~ unit. The carbonaceous material is fed through feed holes 4 in the back die 3. The carbonaceous material is formed into fuel element rods having the desired slot or hole pattern determined by thz front die 5. Line 10 speed is controllsd by the velocity contrsl on the extrusion press. The extrusion of ~he carbonaceous fuel element rods causes ~he ribbon to be pulled along through the slot in the back die 3, thereby embedding the ribbon 1 in the extruda~e.

In the second preferred method, the coextrusion method, two 15 extrudable mixtures are prepared, one comprising the combustible carbonaceous fuel composition, the other comprising a non-burning composition, e.g., a graphite. Binders typically employed in the formation of extruded lFueJ compositions may be employed in both extrusion mixtures. One preferred binder for use in this process is carbvxymethylcellulose ((::M(~

The combustible fuel compositions useful herein may be any of those carbonaceous fuel compositions described in ~he patents recil:0d in the Background of the Invention, suPra. Preferred carbonaceous fuel compositions are described in U.S. Patent No. 5,178,167 to Rig~s et al.
They generally comprise burnable carbonaceous îuel, a binderr sufficient water to provide the consistency of a workable paste ~gen~rally 32-409~ by weight), and various other materials to proved desired characteristics.
.

2:10~22 The non-burning composition us~ful herein generally comprises from about 5 to 90 wsight percant of a graphite having a density of about 1.3 - 1.9 g/cc. Other non-burning inç~redients may also be used, e.g., non-burning fillers such as CaC03, ciays such as bentonite, and the like. When fillers or sxtenders are used with graphite, they may con~ribute up to about 80 weight percent of the mixture, preferably from aboln 10 to about 60 percent, and most preferably about 4û percent of the non-burning composition. A binder is typically used to hold the non-burning composition together. Preferred binders include CMC, SCMC, sodium alginate, etc. The compositions are extruded from mixes containing sufficient water to provide the consistency of a workable paste, generally about 32-40% water by weigh~.

In the coextrusion process, at least ~o extruders feed a common die, such that the extrudates create the desired placement of the non-burning composition within the burning 7uel rod. The shapes and sizes o~ the two (or more) components can be varisd as desired. The resulting continuous rocl having a non-burnin~ portion located therain is then dried and cut to length as desired. A coextrusion die is illustrated in Figure 9.

As illustratsd in Figures 9 and 9A, one coex~rusion process involves feedin~ the non-burning material 11~ ints the feed tube 102. The feed tube 102 feeds the non-burning ma~erial into the back die 103 and the material is formed into a strip. The burnable carbonaceous 106 composition is fed into the die assembly through a side port in the die holding unit and fed through feed holes 1û4 in the back die 103. The carbonaceous material 106 and non-burning material 100 are formed into fuel rods having the tlesired slot or hole pattern dictated by the front die 10~.

The fuel element 120 shown in cross section in Figure 10 has two non-burning sections, 121 and 122 which are extmded into corresponding slots 2~6322 123 and 124 formad during extrusion of the burnable carbon ~uel body. The fuel has a pluraiity of grooves 125 which aid in lighting the fuel and in heat transfer characteristics o~ tha fuel. When the fuel element bums, the non-burning portions remain. In a cigarette1 the last portion, e.~. 6 mm, of the ~uei is circumscribed by a layer having little or no ~r permeability, and which couldconduct very substantial amounts of hea~ away from the fuel. Such structures cause the segment of burnable carbon located between the non burnable portions 121 and 122 to extinguish, so tha~ a plug ~f unburned but burnable carbonaceous fuei remains betNeen the non-burnable portions 121 and 122 over the last few millimeters of the ~uel element. In such an ernbodiment, the amoun~ of burnable fu01 which remains a~er extinguishing of the cigarette is controlled.

A preferred device ~or producing the struc~ure of Fig. 10 is shown in Fig. 11. The extrusion die 130 has a first forming segment 131, which corresponds to the shape of the burnable carbonaceous fuet, including protrusions 132 and 133 which form the slots 123 and 124 in the fuel element (Fig. 10), and protrusions (not shown3 which form the grooves 125 in the finished fuel element. The first forrning segment terminates at point 134, at which point channels 135 and 136 are provided to form the non-burning portions in the slots 12~ and 122, where they contact the burnable carbonaceous fuel body. The non-burnin~ material is supplied to channels 135 and 136 via passageways 137 and 138, respectively, which preferably are maintained at constant prsssure, so that the supply of non-burnable material to slots 135 and 16 ramains reiatively constant. The non burning material remains in the finished product, and protrudes from the upper and lower circumference of the burnable fuel body, as shown in Fig. 10. Those protruding non-burning portions make solid contact with the circumscribing insulating ma~erial, and thus aide in retaining the fuel element in the smoking article throughou: smoking.

21~6322 When employed in a cigarette, the fuel eiement is advantageously circumscribad by an insulating and/or retaining jacket material. The insulating and retaining material preferably (i) is adapted such that drawn air can pass therethrough, and (ii) is positioned and configured so as to hold the fuel element in place. Preferably, the jacket is flush with the ends of the fuel element, however, it may extend from about 0.5 mm to about 3 mm beyond each end o~ the fuel element.

The components of the insulating and/or retaining matarial which surrounds the ~u01 element can vary. Exarnples of suitable materials include glass fibers and other materials as dascribed in U.S. Patent No. 5,105,~38;
European Patent Publication No. 336,690; and pages 4~52 of the RJR
Monograph, suPra. Examples of other suitable insulating and/or retaining materials are glass flber and tobacco mixtures such as those described in U.S.
Patent Nos. 5,119,B37, 5,105,838, 5,065,776 and 4,756,318.

Other sultable insulatin~ andlor retaining materials are gather~d paper-type materials which are spirally wrapped or o~herwise wound around the fuel element, such as those described in copending U.S. Patent No. 5,105,836 to Gentry et al. The paper-type materials can be gathered or crimped and ga~hered around the ~uel elernent; gathered into a rod using a rod making unlt available as CU-10 or CU20S from DeCoufle s~a.r.b., together with a KDF-2 rod making apparatus from Hauni-Werke Korber & Co., KG, or the apparatus described in U.S. Patent No. 4,807,BO9 to Pryor et al.; wound around the fuel element about its longitudinal axis; or provided as longitudinally extending strands o~ paper-type sheet using the typss of apparatus ~escribed in U.S.
Patent Nos. 4,889,143 to Pryor et al. and ~,025,814 to RakerO

210g322 Examples of paper-type sheet materials are available as P-2540-13~E
carbon paper and P-2674-157 tobacco paper from Kimberly-Clark Corp.; and preferably the longitudinally axtending strands of such materials ~e.g., strandsof abou~ 1/32 inch width) extend along the iongi~ude of the fuel elemerlt. The 5 fuel element also can be circumscribed by tobacco cut flller (e.g., flue-curedtobacco cut filler ~rea~ed with about 2 w~ight percent potassium carbonate).
The number and positioning of the strands or the pattern of the gathered paper is sufflciently tight to maintain, r~ain or otherwise hold the eomposite fuel elernant structure within the cigarette.

As illustrated in Figs. 1 & lA, the in~ulating jacket which surrounds the fuel element is circumscribed by a paper wrapper. Suitable papers for use herein are described in U.S. Patent Nos. 4,938,238 and 5,105,837.

As desoribed ab~ve, the substrate carries aerosol forming materials and other ingredients, e.~., flavorants and the like, which, upon ~xposure to heated1~ gases passing through the aerosol generating means during puffing, are vaporized and delivered ~o ~he user as a smoke-like aerssol. Preferred aerosol forming materials used herein include glycerin, propylene glycol, water, and the like, flavorants, and other optional ingredients. The patents referred to in the E~ackground of the Invention (suDra) teach additional useful 20 aerosol forming materials that need not be repeated here.

The substrate rods are advantageously formed using commercially available aquipment, particularly eigarette filter making equipmant, or cigaralte rod forming equiprnent. Two preferred commercially avail~ble appar~tus useful in forming the substrates o~ the present invention are the DeCoufle filter 25 making equipment (CU-10 or CU20S) available from DeCoufle s.a.r.b. and a modified rod forming apparatus, the KDF-2, available from Haunie-Werke Korber & Co., KG.

- 2û -In m~st embodimen~s ~ the present invention, the combination of the fuei element and the substrate (also known as the front end assembly) is attached to a mouthend piece; although a disposable fuel elemenVsubstrate combination can be employed with a separate mouthend piece, such as a 5 reusable cigaret~e holder. The mo~hend piece provides a passageway which channels vaporiz~d aerosol forming materials into the rnouth of ~he smoker;
and can also provide fur~her flavor to the vaporized aerosol forming materials.
Typically, the length of the mouthend piece ranges from 40 mm to about 8 mm.

Flavor segments (i.e., segments of ~athered tobacco paper, tobacco cu~ filler, or the like) can be incorpora~ed in the mouthend piece or the substrate segmant, e.g., either directly behind the substrate or spaced apart therefrom, to contribute flavors to ths aerosol. ~;athered carbon paper can be incorporated, particularly in order to introduce menthsl fl~vor to 1he aerosol.
Such papers are described in European Patent Publication No. 432,538.
Other flavor segments useful herein are described in U.S. Patent Nos.
5,0~6,295 and 5,105,834 and European Patent Publication No. 434,339.

The present inven~ion will be further illustra~ed with reference to ~he following examples which aid in the understanding of the present invention, 20 but which are not to be construed as limitations ~hereof. All percentages reported herein, unless othenNise specified, are percent by weight. All temperatures are expressed in degree~ Celsius.

Referenee Fuel Element A reference fuel element, i.e., a non-composite fuel element, is prepared 21~322 as follows:

A fuel element 12 mm long and 4.5 mm in diameter, and having an apparent (bulk) density of about 1.02 glcc is prepared from about 82.~5 parts hardwood pulp carbon having an average particle size of 12 microns i 5 diameter, 10 parts ammonium alginate (Amoloid I IV, Kelco C:o.), 0.9 parts Na2C;03, 0.75 parts levulinic acid, 5 parts, ball-milled American blend tobacco and 0.5 parts tobacco extract, obtained as described in U.S. Patent No.
5,1~9,942.

The hardwood pulp carbon is prepared by carbonizing a non talc 10 containing grade of Grande Prairie Canadian kra~t hardwood paper in an inert atmosphere, increasing the ~emperature in a step-wise manner sufficient to minimize oxidation of the paper, to a flrial carbonizing temperature of at least7~0C. The resuiting carbon ma~srial is cooled in the inert atmosphere go less than 35C, and then ground to fin~ power havin~ an a~erage particle size (as 15 d~termined using a Microtrac Analyzer, Leeds ~ Northrup~ of about 12 sm in diameter.

Tha finely powdered hardwood carbon is dry mixed with the ammonium alginate binder, levulinic acid and ~he ~obaccos, and then a q/0 wt. aqueous solution of Na2C0, is added to provide an ex~rudable mixture, having a final 20 sodium carbonate level of about 0.9 parts.

Fuel rods (each about 24 inches long) ars extruded using a screw extruder from the rnixture having a generally cylindrical ehape about 4.5 mm in diameter, with six ~6) equally spaced periph4ral ~rooves tabout 0.5 mm wide and about 1 mm deep) with rounclsd bottoms, running from end to end. The 25 extruded rods have an initial moisture level ranging from about 32-34 weight percent. They are dried a~ ambient temperature for about 16 hours and the 2~322 final moistura content is about 7-8 weight percent. The dried cylindrical rods are cut ~o a length of 12 mm using diarnond tipped steel cutting wheels.

O~AMPLIE 2 Coextrusion Method An extrudable non-burning compo~ition is prepared cornprising a 1:1 (by weight) mixture of CaC03 and graphite h~ving a densi~y of 1.3 together with 8 parts CMC binder and sufficient water added to give a workable paste, in this case about 35% by weight.

An extrudable burnable carbonaceous fuel composition comprising 10 weight percent CMC binder, 90 wei~ht parcent carbon having an avara~e particle size (Micro~rac) ~12 ~.m and about 38% water is prepared.

The non-burnin3 composi~ion is fed into a feed tube whieh feeds the non-burning material into a baek die to form the composition into a strip. The burnable carbonaceous fuel composition is fed into the die assernbly ~hrough a side port in the die holding unit and fed through feed hole~ in the back die.
The burnabie carbonaceous material and the non-burninçl ma~erial ~hereby become integral in the desired configuratiorl, and exit the die at the front endas fuel rods having the desired diameter and slot or hoie pa~tern dictated by the front die. The resulting 4.5 mm diameter rods are air dried and cut into fuel element lengehs 112 mm). They have the cross sectional conflguration depicted in Fig. 2. The graphite non-burning segment ha~ a thickness of 0.22 inches, and ths depicted grsoves have a width of 0.018 inches and terminate in radiuses of 0.09 inch. The sro~ves have a depth of about 0.04 inches at their deepest point. The diameter of thP graphite non-burning segment was about 4.9 mm.

21~632~

~MPLE 3 Ribbon Pull Method An extrudable eombustible carbonaceous fuel mixture is ~rmed with 10 weiyht percent CMC binder, 90 weight percent of oarbon having an aYerage 5 particle size (Microtrac) of 12 sm, and water up to 38% based on solids.

A graphits foil ribbon 0.010 inches (0.254 mm) thick by 0.200 inches (5.08 mm) wide, having 0.~80 inch (2.032 mm) diameter holes punched every 1/8 inch (3.175 rnm) is fed into the back of an extrusion feed tube and ~hrough the back an extrusion die. The ribbon is then pulled through the bumable 10 carbonacsous fuel composition that is fed into the die assembly through a side port in the die holding unit. The carbonaceous material is simultaneously fed through feed holes in the back die. The carbonaceous rnaterial, surrounding the foil ribbon, is formed into continuous fuel element rods having ths desired diameter and slot or hole pattern, as determined by the si~e and 15 shape o~ the front die. Lins speed is controlled by ths velocity controi on the extrusion press. The extrusion of the carbonaceous fuei element rod causes the ribbon to be pulled along throu~h the slst in the back die, thereby ernbedding the ribbon in ~he extrudate.

The 4.5 mm diameter composite ribbon eontaining fuel rod is air dried 20 and cut into appropriate fuel element lengths (12 mm).

2~0~32~

EXP~MPl.E 4 Coextrusion Method An extrudable non-burning composition is prepared comprising a 1:1 (by weight) mixture of CaCO I and graphite having a density of 1.3 together with 8 parts CI~AC binder and suFficient wa~ter added to give a workable paste, in this case about 33% by weigh~.

An extrudable burnable carbonaceous fuel composition comprising 10 weight percent CMC binder, 90 weight percent carbon having an av~rage particle size (Microtrac) of 12 ~m and about 37% water is prepared.

The burnable carbona~eous ~u~l composition is ~d into the die assembly depicted in Fig. 11, throu~h a port in the end of the die. The non-burning composition is fed into a feed ~ube which f~eds the non-burning material into tubes 137 and 138. The non-burning material is formed into tNo non-burnin~ portions or segments 121 and 122, by the shape of passagew~ys 1~ 135 and 136. The non-burning material contacts the burnable carbonaceous fuel along the bottom and sides of slots 123 and 124. The burnable carbonaceous materiai and the non-burnin~ material thereby become Integral in the desired configuration, and ~xit the die at the front end as ~uel rods having the desir~d diameter and slot or hol~ pattern dictatsd by the front dis.
20 The resulting 4.2 mm diameter rods are air dried and cut into fuel element lengths (12 mm). They have the cross sectional configuration depicted in Fig.
10. The gfaphite non-burning segments have a heigh~ of ~.025 inches, and protrude abovs the surface of the burnable rod 0.2 mm. The protruding par~
of the non-burnin,3 s~tions have the shape of an arc of a right cylinder having a radius of 0.03 inches. The base of the non-burning portions is 0.04 inches in width. The depicted grooves have a width of 0.016 inehes and terminate in ~063~2 radiuses of 0.08 inch. The grooves all terminate at a point about 0.037 inches from the vertical axis of the element as depicted, and tha grooves are spaced apart about 0.041 inch, center line to center line.

5 Burn Characteristics Burning characteristics of fuel elements are determined usin~ the modified Phoenix Precision Instruments Model JM-6500 aerosol spec~rom~er, available from the Virtis Company, Gardiner, New York.

The modifled JM-6500 instrument provides measurements of total 10 carbon dioxide, total catbon monoxide, and total calories generated during the burning of the fuel elements. The instrument also provides a puFf-by-puff analysis of those data.

For each example, five fuel elements are jacketed and smoked using the modified JM-6500 instrument for 20 pu~s under 50i30 smoking conditions.
15 Thess conditions consist of a 50 ml puff volumc of two seconds duration, separated by 28 seconds of smolder time. Lighting of the fuel elements was by application of a standard li~hter flame to the face of the fuel elements for five seconds duratiorl before drawing the first puff under 50/30 smoking conditions.

. ,.

21~322 Tha results obtained for the reference fuel element of Example 1 are as follows:

Average Total CO2 87 mg Average Total CO 22 mg Average Total Calories 209 Average CO/Calories 0.105 The results obtained for the coextruded fuel elements of Example 2 are as follows:

Average To~al CO2 82 mg Average Total CO 16 rng Average Total Calories 190 Average CO/Calories 0.082 The r~sults obtained for the ribbon-pull fuel elemen~s of E~xample 3 are as follo~Ns:

A~erage Total CO2 63 m~
Average Total CO 12 mg Average Total Calories 146 Average CO/Caiories 0.080 The results obtained for the coex~rLJded fuel elements o~ xample 4 are 20 as follows:

Average Total CO2 68 mg Average Total CO 17 mg Average Total Calories 160 Average CO/Calories 0.105 , .

21~322 Cl~:ARETTE

Fuel Element A fUBi element prepared as in Example 2, 3 or 4 is employed. The 5 length of the fuel elemsn~ is 12 mm and the diameter is 4.~ mm in the case of axamples 2 and 3, and 4.2 mm in the case of Example 4.

Insulatina Jacket A 12 mm long, 4.5 mm diame~er plastic tube is overwrapped with an insulating jacket material that is also 12 mm in l~ng~h. In these cigarette 10 embodiments, the insulating jacket is composed of 2 layers of Owens-Corning C-glass rnat, each about 1 mm thick prior to being compressed by a Jacket forming machine (e.g., such as that desGribed in U.S. Patent No. 4,807,809), and after forma~ion, each being about 0.6 mm thick. Sandwiched behNeen the two layers of C-glass is one sheet of reconstituted tobacco paper, Kimberly-Clark's P-2831-189-M. A cigarette paper, designated P-3122~153 from Kimberly-Clark, ovenNraps the ou~er layer. The reconstitLIted tobacco paper sheet is a paper-like sheet made from tobacco, additionally containing a blended tobacco extract. The width of the reconstituted ~obacco sheets prior to forming are 19 mm for the inner sheet and 26.5 mm for the outer sheet.
20 The final diameter of the jacketed plastic tube is about 7.5 mm.

Substrate A substrate rod about 7.5 m in diameter is formed from a highly embossed, 36 g/m2, 152 mrn wide web of paper containing 25% calcium 2~06322 sulfate available from ~Imberly-Clark as P3284-19, e.g., on a modified KDF-2 rod forming apparatus. The substrate rocl is overwrapped with Simpson paper RJR-002 which is coated on both sides the Hercon 70. The overwrapped rod is cut into 10 mm segm0nts weighing approxim~tely 55 mg.

Tobacco Paper Pluq A tobacco paper rod about 7.5 mm in diameter is formed from a medium embossed, 127 mm wide web of tobacco paper designated as P-144-GNA-CB available 7rom ~Imberly-Clark, e 9 1 using a rod forming apparatus such as that disclosed in U.S. Patent No. 4,807,809. The rod is overwrapped with a 26.5 mm wide paper P1487-184-2 from Klmberly-Clark and cut into 10 mm lengths.

Front End Overwrap A front er~d overwrap paper is formed by laminating several papers including; an outer layer of Ecus~a 456 paperj an intermediate layer of 0.0005 cm foil and an inner layer of tissue paper, 12.5 Ibs/ream, 20.4 g/m2. The laminated layers are held together with a commercial adhesive, AirFlex 465, using 1.5 Ibs/ream.

Aerosol Tube A paper aerosol tube about 7.5 mm diameter is made from a web of 112 gsm basis wei3ht Simpson RJR-002 paper, about 27 tnm wide, having a thickness of about 0.012 inch. The RJR-002 paper is formed into a tube by lapjoining the paper using a water-based ethylene vinyl acetate adhesive.
The inner and outer surface of the paper tube is coated with a Hercon-70.
The paper is cu~ into segments 31 mm in ierlgth 2~0~322 Mouth End Tube A paper mouth end tube about 7.5 mm diameter is formed from Simpson paper, Type 002-A, lap joined using a hot-melt adhesive No. ~48-1 96K, available from the R.J. Reynolds Tobacco Company. The formed tube 5 is cut into 40 mm length segments.

Filter Pluq A polypropylane filtar rod abou~ 7.5 rnm in diameter is formed from a PP-100 mat, about 260 mm wide, availabl~ from Kimberly-Clark and overwrapped with a 28.5 mm wide web of paper P1487-184-21 available from 10 Kimberly-Clark, e.g., using the appar~tus described in U.S. Patent No.
4,80~,809. The overwrapped rod is cut into 20 mm length segments.

Tobacco Roll A reconstituted tobacco cut filler prepared as described in U.S. Patent No. 5,159,942, is forrned into a rod about 7.5 mm in diameter and 15 overwrapped with paper, e.g., using the apparatus described in U.S. Pa~ent No. 4,807,809. The overwrapped tobacco roll is cut in~o 20 mm lengths.

Assembly of Ci are~te A. Front End Piece Assembly A 10 mm long substrate piece is inserted into one end of the 31 mm 20 long aerosol ~ube and spaced about 5 mm from the end, thereby forming a void space of about 5 mm. Approximately 150 mg of a rnixture comprising glycerin, tobacco extract and other flavors is applied to the substra$e. A 10 210~322 mrn long tobacco paper plug is inserted into the other end of the aerosol tube until the mouth end of the tobacco paper plug is flush with the mouth end of the aerosol tube.

A 12 mm long insulating jacket pie~cs is aligned with the front end o~ the 5 aerosol ~ube so tha~ the insulating Jacket piece is adjacent the void space in the aerosol tube, The insulating ja~ket piece and the aerosol tube are circumscribed with a piece of front end overwrap paper, approximately 26.5 mm x 37 mm. The tissue paper side of the overwrap paper (suPra~ is placed toward the aerosol tube and a seam adhesive (21~8-69-1) available from the 10 H.B. Fuiler Co., Minneapolis, MN, is used to seal the overlap joint. The 37 mm length of the overwrap is aligned in the longitudinai direction so that the overwrap paper extsnds from the free end of the aerosol tube to approxima~ely 6 mm over the insulating jacket, leaviny approximately 6 mm of the insulating jacket exposed.

The plastic tube in the insulating jacket piece is removed and a 12 mm long fuel element is inserted so that the end of the fuel element is flush with the end of the insulating jacket.

B. Mou~hend Piece Assembly A 20 mm filter plug is inserted into one end of the mouthend tubs and a 20 20 mm tsbacco roll inserted into the other end of the mouthend tube so that the plug and roll are flush with the ends of the mouthend tube.

The mouthend piece assembly and the front end piece assembly are aligned so that the tobacco roll abuts the tobacco paper plug and are secured together by a piece of tape to form a cigarette.

210~322 The cigarette is smoked, and yielcls visible aerosol and tobacco flavor (i.e., volatilized tobacco components) on all puffs fcr about 1~12 puffs. The fuel element burns to about 6 mm back, i.e., to about the region where the foil lined ~ube overwraps the fuel element, and there the cigarette self-5 ex~inguish2s.

PREPAIFlATION OF CONlPONE~NTS

Jacketed Fuel Rod A jacketed fuel rod approximately 7.5 mm in diameter, including a fuel 10 element prepared according to any of Examples 2, 3, or 4, and an insulatingmaterial is prepared by directly extruding the carbonaceous fuel rod into a multilayer glass fiber/tobacco paper ribbon. The jacketed fuel rod is cut into lengths of about 72 mm.

Jacket Material The jacket material is composed of 2 layers of Owens-C;orning C-glass mat, each about 1 mm thick prior to being corrpressed by a jacket forming machine (e.g., such as that described in U.S. Patent No. 4,807,B09), and after formuiation, sach being about 0.6 mrn thick. Sandwiched'between the ~wo layers of C-glass is one or two sheets of reconstituted tobacco paper, ~Imberly-Clark's P-3510-9~2. A eigarette paper, designated P-3122-153 from Kimberly-Clark, overwraps the outer layer. The recorlstituted tobacco paper sheet, is a paper-like sheet containing a blended tobacco extract. The wid~h 21~322 of the reconstituted tobacco sheets prior to forming is about 17 mm, while the width of the cigaretts paper outer sheet is about 25.5 mm. The seam adhesive used for the outer wrap can be a cold seam adhesive CS 1242, available from RJR Packaging, R.J. Reynolds, ~nston-Salem, N.C.

5 Substrate Tube A continuous substrate rod about 7.5 mm in diameter is formed from a wide, highly embossed, 36 gsm, about 7 inch wide web of paper containing 25% calcium sulfate available from Kimberly-C:lark ~KC) as P3284-19, e.g., on a modified KDF-2 rod forming apparatus. The substrate rod is overwrapped 10 with a paper/foil lamina~e having a width of about 24.5 mm, the foil being a continuous case 0.0005 aluminum foil, and the pap~r being a Simpson Paper Co. ("Simpson") RJR 002A paper. The lamination adhesive is a silicate adhesive, No. 0~50-05-0051, available from RJR Packaging. A Center line adhesiv2, cold adhesive CS 1242M, available from RJR Packaging, is spray 15 applied to the laminate, to hold the substrate in place within ~he wrap. The seam is sealed with hot melt adhesive 444-227, from RJR packaging.

The overwrapped rod is cut into 60 mm segments. Approximately 900 mg of an aerosol forming matsrial comprising glycerine, propylena glycol, and flavorants, such as tobacco extract, i5 applied to ~he web during formation of 20 the continuous substrate rod. The substrate segment is cut in~o substrate plugs about 10 mm in length and ovenNrapped with a Simpson RJR
002A/0005 foil larninate describsd above, having a width of about 25.5 mm.
The plugs are placed at alternate intsrvals of 10 and 12 mhn along the tube.
Ths plugs are adhered to the tube by corresponding application of hotmelt 25 adhesive No. 44~37A, RJR Packaging. The seam is ~ealed with hot melt adhesive 444-227, from RJR packaging.

21~6322 The continuous tube is cut into substrate void tube sections about 42 mm in length having a center void about 12 mm, two substrate plu~s 10 mm wide, and void space ~t each end of about 5 mm in width.

Tobacco Section A r~constituted tobacco cut filler pr~pared as described in U.S. Patent No. 5,159,942, is formed into a rod about 7.5 mm in di~meter and overwrapped with papcr, e.g. KC 645, 25.5 mm in width, using a Protos cigarette making machine, using a standard ~ipping adhesive. The overwrapped tobacco roll is cut into 12û mm length segments.

A tobacco paper rod about 7.5 mm in diameter is formed from a rnedium embossed, 127 mm wide web of tobacco paper designated as P~
GNA-CB available from Kimberly-Clark, e.g., using a rod forming apparatus such as that disclosed in U.S. Patent No. 4,807,809. The rod is overwrapped with a KC paper P1487-184-2, about 25 mm wide, and cut into 80 mm length 1 5 segments.

The ~obacco roll and tobacco paper segments are cut into 40 mm and 20 mm segments respectively ~nd are aligned in an alternating arrarlgement and overwrapped with a wrapper o~ KC 646 paper, 25.5 mm in width, using a center line hot melt adhesive 44~37A, RJR Packaging, and a searn adhesive, M8-195K hot melt, RJR Packagin~. The combined $obacco rollnobacco paper assembly is cu~ into a 2-up tobacco section 60 mm in length having a 40 mm tobacco roll cen~er segment.and 10 mm tobacco paper segment on each end of the tobacco roll segment.

2~06322 Fi!ter A polypropylene filter rod about 7.6 mm in diameter is formed from a PP-100 mat, about 260 mm wide, available from Klmberly-Glark and overwrapped w~th a web of paper P1487-184-2, having a width of 25.5 mm, 5 available from ~mberly-Clark, e.g., using the apparatus described in U.S.
Paten~ No. 4,8û7,809, and hot melt 448-195K seam adhesive. The overwrapped rod is cut into 80 mm Icngth se~m~nts.
.

CIGARE~E ASSEMIBLY

Fuel Subs~rate Section 10A jacketed fuel rod is cut into fuel alements 12 mm in length. Two fuel elements are positioned on opposit~ sides of a substrate void tube section and aligned. These componants arc overwrapped with a wrapper about 26.5 mm in width and about 54 mm in length, comprising a paper/foil/paper laminate, comprisin~ Ecusta 15456 paper/continuous cast 0.0005 foil/Ecusta 1529492 paper, which are laminated to the foil using Airflex Adhe~ive 465. The laminat~ is adhered to the jacketed fuel and the substrat~ void tube assembly, by cold aclhesiue MT-8014, RJR Packaging, applied to the entire inner surFace of the laminate. The wrapper overwraps the substrate tube and extends to within about 6 mm of the free end of each fuel element to form a 2-up fuel 20 substrate section.

Tobacco Fuel Unit A 2-up fuel/substrate section is c~ at its midpoint and positioned on opposite sides of a 2-up tobacco section and aligned so that the void end of each fuel-substrate section is adjacent and abuts the tobacco papcr plugs at 2tO632~

each end of the 2-up tobacco section. The assembled components are overwrapped with custa E30336 paper, about 70 mm in length and about 26 mm wide. The wrapper is adhered to the fuel substrate section and the tobacco section assembly with MT-8009 ladhesive ~RJR Packaging) to form a 5 2-up tobacco-fuel unit approximately 126 mm in length.

Ciaarette A 2-up tobacco-fuel unit is cut at its midpoint and positioned on opposite sides of a 2-up filter unit and aligned so that the tobacco roll end ofa single tobacco-fuel unit is adjacent and abuts the 2-up flUer. The assembled 10 components are overwrapped with a tipping wrapper, RJR tipping code No.
1000011, approximately 50 mm in length and about 26 mm in width which extends approximately 5 mm ovar each of the junctures betNeen the 2-up fllter and each tobacco-7uel unit. The wrapper is adhered over its erltire area to the assembled components with an adhesive MT-8009 (RJR Packaging) 100%
15 coverage, to form a 2-up cigare~te. The 2-up. ci~arette is cut at approximately its midpoint (i.e., the midpoint of tha 2-up filter) to form a single ci~arette.
The present invention has been described in detail, including the prefsrred embodirnents thereof. HoweYer, it will be appreciated that those skilled in the art, upon consideration of the present disclosure, rn~y make 20 modifications and/or improvements on this invention and still be within the scope and spirit of this invention as set ~orth in the foilowing claims.

Claims (25)

1. A composite fuel element for smoking articles comprising at least two different materials, contiguous throughout the length thereof, including a carbonaceous material which burns, and a material which does not burn significantly when compared to the burning material, and wherein said fuel element has a length of less than about 20 mm before burning.

2. The composite fuel element of claim 1, wherein at least a portion of said non-burning material extends beyond the periphery of said burnable material.

3. The composite fuel element of claim 1, wherein the non-burning material included in the fuel element comprises a heat exchange material.

4. The composite fuel element of claim 1, comprising a plurality of segments of non-burning material.

5. The composite fuel element of claim 3, wherein the heat exchange material comprises a non-burning carbon.

6. The composite fuel element of claim 3, wherein the heat exchange material comprises a graphite foil.

7. The composite fuel element of claim 3, wherein the heat exchange material comprises a metal ribbon or foil.

8. The carbonaceous fuel element of any one of claim 1, 2, 3, 4 or 5, wherein the non-burning material further comprises one or more binders.

9. An extruded composite fuel element for smoking articles comprising at least two different coextruded materials contiguous throughout the length thereof, including a carbonaceous material which burns, and a carbonaceous heat exchange material which does not burn significantly when compared to the burning material, and wherein said fuel element has a length of less than about 20 mm before burning.

10. The extruded composite fuel element of claim 9, wherein at least a portion of said heat exchange material extends beyond the periphery of said burnable material.

11. The extruded composite fuel element of claim 10, wherein the heat exchange material in the fuel element comprises a carbon.

12. An extruded composite fuel element for smoking articles comprising at least two different materials contiguous throughout the length thereof, including a carbonaceous material which burns, and a metal heat exchange material which does not burn, and wherein said fuel element has a length of less than about 20 mm before burning.

13. The extruded composite fuel element of claim 12, wherein at least a portion of said metal heat exchange material extends beyond the periphery of said burnable material.

14. The extruded composite fuel element of claim 12, wherein the metal heat exchange material has the form of a ribbon or foil.

15. A cigarette comprising:
a carbonaceous fuel element less than about 20 mm in length prior to smoking, said fuel element including a jacket of resilient insulating material around its circumference; and a physically separate aerosol generating means disposed longitudinally behind said fuel element, said aerosol generating means including a substrate bearing an aerosol forming substance; and wherein said fuel element further comprises at least two materials, contiguous throughout the length thereof, including a carbonaceous material which burns, and a non-burning material, a material which does not burn significantly when compared to the burning material.

16. The cigarette of claim 15, wherein at least a portion of the non-burning material in the fuel element extends beyond the periphery of the burnable material.

17. The cigarette of claim 15, wherein the non-burning material in the fuel element comprises a heat exchange material.

18. The cigarette of claim 17, wherein the heat exchange material comprises a non-burning carbon.

19. The cigarette of claim 17, wherein the heat exchange material comprises a graphite ribbon or foil.

20. The cigarette of claim 17, wherein the heat exchange material comprises a metal ribbon or foil.

21. A method of reducing the average temperature of carbonaceous fuel elements for smoking articles comprising forming such fuel elements as a composite member comprising at least two different materials, contiguous throughout the length thereof, including a carbonaceous material which burns, and a material which does not burn significantly when compared to the burning material.

22. The method of claim 21, wherein the non-burning material in the fuel element comprises a heat exchange material.

23. The method of claim 22, wherein the heat exchange material comprises a non-burning carbon.

24. The method of claim 22, wherein the heat exchange material comprises a graphite ribbon or foil.

25. The method of claim 22, wherein the heat exchange material comprises a metal ribbon or foil.