FI83020B - Aerosol-forming material for use in a smoking product - Google Patents

Description

1 83020

Aerosol-forming material for use in a smoking article. - Aerosol generating materials for the production of the product.

The present application, separated by application of 891196, relates to an aerosol-forming material according to the preamble of claim 1 for use in a smoking article.

Many smoking products have been developed over the years, especially in the last 20-30 years, but none of these products have ever achieved commercial success.

Despite decades of interest and business, there is still no smoking product on the market that has the advantages of conventional cigarettes without producing significant amounts of the incomplete combustion and pyrolysis products of a conventional cigarette.

The invention relates to an aerosol-forming material according to the preamble of claim 1, which is characterized by the features set forth in the characterizing part of claim 1. The applicant's own earlier FI patent 78228 already mentions alumina as one of the possible substrate substances. However, that publication does not disclose the possibility of using heat-treated alumina, and in particular the use of heat-treated alumina at temperatures above 1000 ° C. The aerosol-forming material according to the invention is suitable, for example, for a smoking article, which is preferably in the form of a cigarette, and which uses a small high-density combustible fuel element together with a physically separate aerosol-forming part containing one or more aerosol-forming materials. The aerosol generating member is preferably in a conductive heat exchange relationship with the fuel element and / or at least a portion of the fuel element is surrounded by a flexible insulating sheath 2 83020 to reduce radial heat loss. When ignited, the fuel element generates heat which is used to vaporize the aerosol-forming materials in the aerosol-forming section. Especially during inhalation, these volatile materials retract towards the mouth end and further into the user's mouth in the same manner as the smoke of a conventional cigarette.

Such smoking articles are capable of generating significant amounts of aerosols both in the early stages and throughout the life of the article and provide the user with the impressions and benefits of smoking a cigarette. The aerosol produced by the aerosol generating member is formed without significant thermal decomposition and preferably transfers to the user significantly less amounts of pyrolysis and incomplete combustion products than a conventional cigarette normally produces.

The length of the small fuel element used in such a smoking article is less than about 30 mm, preferably less than about 20 mm, and has a density of at least about 0.5 g / cm 3, more preferably at least about 0.7 g / cm 3 as measured, for example, by mercury shift. Suitable fuel elements can be molded or extruded from comminuted or remixed tobacco and / or tobacco substitute and preferably contain combustible carbon. Several longitudinal channels, more preferably 5-9 channels or more, are formed in the fuel elements to help direct heat transfer from the combustible fuel element to the aerosol forming materials in the aerosol generating section. The ducts are so close together that during combustion they merge into a single passage at least at the ignition end of the fuel cell.

The aerosol generating member preferably includes a substrate or carrier of heat-resistant material that supports one or more aerosol-forming materials. The conductive heat exchange relationship between the fuel and the aerosol generator is preferably achieved by providing a thermally conductive portion, such as a metal conductor, in contact with the fuel element and the aerosol generating member and efficiently conducting or transferring heat from the combustible fuel element to the aerosol generating member. This heat conductor member preferably contacts the fuel element and the aerosol generating member at least in part on their circumferential surfaces and is preferably retracted or separated from the combustible end of the fuel element by at least about 3 mm, preferably at least about 5 mm so as not to ignite and ignite the fuel conductor. to avoid duplication. Even more preferably, the heat conducting portion also at least partially surrounds the substrate of the aerosol-forming materials. Alternatively, a separate conductive container may be provided to surround the aerosol-forming materials.

In addition, at least a portion of the fuel element is preferably provided with a surrounding insulating member, such as a sheath formed of insulating fibers, the sheath being preferably a flexible, non-combustible material and at least 0.5 mm thick. This part reduces radial heat loss and helps to retain and direct heat from the fuel element toward the aerosol generating member and further reduces the flammability of the fuel. The preferred insulating member surrounds at least a portion of the fuel element and preferably at least a portion of the aerosol generating member, which helps to mimic the feel of a conventional cigarette. The materials used to insulate the fuel element and the aerosol generating member may be the same or different materials.

Because the fuel element is a relatively short, hot, combustible fire cone, it is always close to the aerosol generating member, maximizing heat transfer thereto and the resulting aerosol production, especially in embodiments with a multi-channel or multi-channel fuel element, heat conductor section, and / or insulation section. The relatively high density fuel material is used to ensure that the small fuel element burns long enough to mimic the burning time of a conventional cigarette 4 83020 and that it generates sufficient energy to generate the required amounts of aerosols. Because the aerosol-forming agent is physically separated from the fuel element, it is exposed to substantially lower temperatures than the temperatures prevailing in the burning fire cone, thus minimizing the potential for thermal decomposition of the aerosol-former.

A smoking article using the aerosol-forming material of the present invention is normally provided with a mouthpiece having, for example, a longitudinal channel member for transferring volatile material generated by the aerosol-forming portion to a user. The mouthpiece preferably includes a flexible outer portion, such as an annular cellulose acetate pad, to mimic the feel of a conventional cigarette. The overall dimensions of the product are preferably the same as those of a conventional cigarette, and therefore the mouthpiece and aerosol delivery portion usually cover about half or more of the length of the product. Alternatively, the fuel element and aerosol generating member may be fabricated without a built-in mouthpiece or aerosol transfer member for use with a separate, disposable or reusable mouthpiece.

A smoking article using the aerosol-forming material of the present invention may also include a dose or plug of tobacco that can be used to enhance the taste of the tobacco to the aerosol. This dose of tobacco can be placed between the aerosol generating part and the mouth end of the product. The annular tobacco part is preferably placed around the circumference of the aerosol generating part, where it also acts as an insulating part and helps to mimic the taste and feel of a conventional cigarette. The tobacco dose may also be mixed with or used as a substrate for the aerosol-forming material. Other substances, such as flavoring agents, may also be added to the product to flavor or otherwise alter the aerosol to the user.

n 5 83020

Smoking products of the type disclosed normally use substantially less fuel by volume and preferably by weight than conventional cigarettes to produce acceptable aerosol amounts. In addition, the aerosol to the user normally has less pyrolysis and incomplete combustion products due to the non-degradable aerosol from the aerosol generating member, and since in particular multi-longitudinal embodiments that the fuel element contains tobacco or other cellulosic material.

In this text and only in connection with this patent application, the word "aerosol" is used to cover vapors, gases, both visible and invisible particles, and the like, and in particular those ingredients which appear "smoky" to the user and are formed by the combustion of a combustible fuel element. substances. As defined in this way, the term "aerosol" also includes volatile flavoring agents and / or pharmacologically or physiologically active substances, whether or not they form a visible aerosol.

As used herein, the term "conductive heat exchange ratio" means the physical arrangement or arrangement of an aerosol generating member and a fuel element by which heat is transferred from a combustible fuel element to the aerosol generating member over substantially the entire combustion cycle of the fuel element. The conductive heat exchange ratio can be achieved by placing the aerosol generating member in contact with the fuel element and very close to the combustible portion of the fuel element and / or utilizing the conductor portion to transfer heat from the combustible fuel to the aerosol generating member. Preferably, both methods can be used to provide conductive heat transfer.

As used herein, the term "insulating member" means any material that acts primarily as an insulator. It is preferred that these materials do not burn during use, but may include slow-burning carbon and the like, and in particular materials that melt during use, such as low temperature glass fiber grades. Suitable insulators have a thermal conductivity of less than about 0.05, preferably less than about 0.02, most preferably less than about 0.005, when the unit is g-cal / (sec) (cm 2) (cm 2) (C ° / cm). See Hackh's Chemical Dictionary, 34 (4th edition, 1969) and Lange's Handbook of Chemistry, 10, 272-274 (11th edition, 1973).

A smoking article utilizing the aerosol-forming material of the present invention will be described in more detail in the following detailed description of the invention with reference to the accompanying drawings, in which:

Figure 1 is a longitudinal section of a prior art smoking article;

Fig. 1A is a sectional view of the smoking article of Fig. 1, taken along line IA-IA of Fig. 1;

Figures 2 and 3 are longitudinal sections of different embodiments of a smoking article utilizing an aerosol-forming material according to the invention;

Figure 2A is an end view of a channel or duct arrangement of a fuel element suitable for use in embodiments of the invention;

Figure 3A is a longitudinal sectional view of a preferred fuel cell channel structure suitable for use in embodiments of the invention.

li 7 83020

The overall dimensions of the prior art embodiment shown in Figure 1 are preferably the same as those of a conventional cigarette and include a short, about 20 mm long combustible fuel element 10, an adjacent aerosol generating member 12 and a foil lined paper tube 14 forming the mouth end 15 of the product. element 10 is extruded or molded from a mixture of comminuted or remixed tobacco and / or tobacco substitute and a small amount of combustible carbon, and the fuel element is further provided with five longitudinal holes 16, see Figure 1A. The ignition end of the fuel element 10 may be tapered or reduced in diameter to facilitate ignition.

The aerosol-forming portion includes a porous carbon mass 13 having 1 or more channels 17 and impregnated with one or more aerosol-forming materials, such as triethylene glycol, propylene glycol, glycerin, or mixtures thereof.

The foil-lined paper tube 14 forming the mouthpiece of the product surrounds the aerosol generating portion 12 and the non-flammable rear end of the fuel element 10 such that the foil-lined tube is approximately 15 mm from the ignition end of the fuel cell. The tubes 14 also form an aerosol passageway 10 between the aerosol generating portion 12 and the mouth end 15 of the product. The presence of a foil-lined tube 14 connecting the non-flammable end of the fuel 10 to the aerosol former 12 improves heat transfer to the aerosol former. The foil also helps to extinguish the fire cone. With only a small amount of unburned fuel left, the heat loss through the foil acts as a heat sink to help extinguish the fire cone. The foil used in this product is typically an aluminum foil with a thickness of 0.0089 mm, but the thickness and / or type of conductor used can vary to achieve virtually any desired β 83020 heat transfer.

The product shown in Figure 1 optionally also includes a tobacco mass or stopper 20 to add flavor or aroma to the aerosol. This tobacco dose 20 may be placed at the mouth end of the carbon mass 13 as shown in Figure 1 or may be placed in the passageway 18 at a distance from the aerosol former 12. For appearance, the product may optionally have a low efficiency cellulose acetate filler or filter 22 placed at the mouth end 15. or close to it.

The embodiment shown in Figure 2 includes a flexible insulating sheath that surrounds or encloses the fuel element to insulate and concentrate heat therein. These embodiments also reduce the risk of fire in a burning cone of fire and, in some cases, help to achieve the feel of a conventional cigarette.

In the embodiment of Figure 2, the flexible fiberglass insulating jacket surrounds the periphery of both the fuel element 10 and the aerosol generating member 12 and is preferably a low temperature material that melts during use. This sheath 72 is coated with non-porous paper 73, such as P 878-5 from Kimberley-Clark. In this embodiment, the fuel element is about 15 to 20 mm long and is preferably provided with three or more holes 16 to improve airflow through the fuel. A suitable channel or bus arrangement is shown in Figure 2A.

In this embodiment, the aerosol generating member 12 is a metal container 74 surrounding a granular substrate 38 and / or compacted tobacco 76, one or both of which contain an aerosol generating material. As shown, the open end 75 of the tank 74 extends over the rear of the fuel element 10 by a distance of 3-5 mm. Alternatively, the open end 75 may abut the rear end of the fuel element 10. The opposite end of the container 74 is folded or crimped to form a wall 78 having a plurality of openings 80 for allowing gases, tobacco aromas and / or aerosol generating material to enter the aerosol transfer passage 18.

The plastic tube 44 abuts or preferably abuts the end wall 78 of the metal container 74 and is surrounded by a flexible, high density cellulose acetate plug 42. A glue 82 or other layer of material may be applied to the fuel side end of the sleeve 42 to seal the sleeve and prevent airflow therethrough. A low efficiency filter 45 is located at the mouth end of the product and the sheath 42 and filter 45 are preferably wrapped in conventional wrapping paper 85. A second layer of cigarette paper 86 may be used to join the back of the insulating sheath 72 and the sheath / filter portion together.

In a variation of the embodiment of Figure 2, the insulating jacket may also be used in place of the cellulose acetate plug 42 so that the jacket extends from the ignition end of the filter 45. In such embodiments, the adhesive layer is preferably applied to the annular portion of the filter that abuts the end of the insulating jacket, or a short annular tuft or fluff portion is interposed between the insulating jacket and the filter body and the adhesive is applied to both ends.

In the embodiment of Figure 3, the sheath 94 includes tobacco or a mixture of tobacco and insulating fibers, such as glass fibers. As shown, the tobacco sheath or layer 94 extends slightly over the mouth end of the metal container 96. Alternatively, it may extend the entire length of the product to the filter at the mouth end. In such embodiments, the periphery of the container 96 is preferably provided with one or more longitudinal slots 99 (preferably two slits 180 ° apart) so that vapors from the aerosol former pass through the annular tobacco portion surrounding the aerosol former to extract tobacco aromas prior to passage 18.

As shown, at the fuel element end of the sheath 94, the tobacco is compressed. This reduces the air flow through the tobacco, thus reducing its combustion power. In addition, the container 96 assists in extinguishing the tobacco by acting as a heat sink.

This heat sink effect helps to suppress the combustion of the tobacco surrounding the capsule and likewise helps to distribute the heat evenly over the tobacco around the aerosol generating part, thus promoting the release of tobacco flavorings. In addition, it may be advantageous to treat a portion of the cigarette paper 85, 89 near the rear end of the fuel with, for example, sodium silicate to aid in extinguishing the tobacco so that it does not burn significantly over the visible portion of the fuel element. Alternatively, the tobacco itself may be treated with a combustion control agent to prevent combustion of the tobacco surrounding the aerosol former.

When ignited, one of the embodiments described above burns, generating heat that is used to vaporize the aerosol-forming material or materials in the aerosol generating member. These volatile materials then retract towards the mouth-side end, especially during suction and further into the user's mouth in the same manner as the smoke of a conventional cigarette.

Because the fuel element is relatively short, the hot, combustible cone of fire is always close to the aerosol generating member, thus maximizing heat transfer to the aerosol generating member and possible tobacco doses and further producing aerosol and possible tobacco flavor, especially when using a preferred heat conducting member. Because the fuel element is short, the product never has a long non-combustible fuel component that would act as a heat sink in previous thermal aerosol products in a common manner. A small amount of fuel or a source of n li 83020 also minimizes the amount of incomplete combustion or pyrolysis products, especially in those embodiments that contain carbon and / or multiple channels.

Heat transfer and therefore aerosol uptake can be improved by using ducts or passages extending through the fuel which draw hot air into the aerosol generator, especially during aspiration. Heat transfer is also improved by a preferred heat conductor portion spaced apart or spaced from the ignition end of the fuel cell so as not to interfere with ignition and combustion of the fuel while avoiding ugly protrusion of the heat conductor portion even after use. In addition, the preferred insulating member tends to enclose, direct and concentrate heat towards the center of the product, thus increasing the heat transferred to the aerosol-forming agent.

Because the aerosol-forming material is physically separated from the fuel element, it is exposed to substantially lower temperatures than those present in a combustible cone of fire.

This minimizes the potential for thermal decomposition of the aerosol former and the associated bad taste. This also results in aerosol formation during aspiration and, in addition, minimal aerosol formation from the aerosol generating member during smoking.

In preferred embodiments, the short fuel element and / or retracted heat conductor and / or insulator and / or pathways in the fuel, together with the aerosol generator, form a system capable of generating substantial amounts of aerosol and possibly tobacco flavor at virtually every aspiration. The proximity of the fire cone to the aerosol former after a few aspirations, together with the conductor portion and / or the insulating portion and / or the plurality of passages in the fuel element, provides good heat transfer both during aspiration and the ratio between aspirations.

Without wishing to be bound by theory, it appears that the aerosol generating member remains at a relatively high temperature between aspirations and that the additional heat generated during aspirations, which is greatly increased by the preferred pathways in the fuel element, becomes primarily used to vaporize the aerosol generating material. This increased heat transfer results in a more efficient use of the available fuel energy, reduces the amount of fuel if necessary, and assists in the initial formation of the aerosol.

In addition, by appropriately selecting the composition of the fuel element, the number, size, shape and placement of the fuel element passages, the insulating jacket, the cover paper and / or the heat conductor part, it is possible to substantially control or adjust the combustion properties of the fuel source. In this way, the transfer of heat to the aerosol former is well controlled and this in turn can be used to change the amount of suction and / or the amount of aerosol to the user.

In general, the combustible fuel elements used in the embodiments shown are less than about 30 mm long. The length of the fuel element is preferably about 20 mm or less, more preferably about 15 mm or less. The diameter of the fuel element is preferably about 8 mm or less, preferably about 3 to 7 mm, and more preferably about 4 to 6 mm. The density of the fuel elements used herein varies from about 0.5 g / cm 3 to about 1.5 g / cm 3 as measured, for example, by mercury displacement. The density is preferably greater than 0.7 g / m 3, more preferably greater than 0.8 g / cm 3. In most cases, a high density material is preferred because it ensures that the fuel element burns far enough to mimic the burning time of a conventional cigarette and generates sufficient energy to generate the required amount of aerosol.

n i3 83020 The fuel elements used herein are preferably molded or extruded from comminuted tobacco, remixed tobacco, or tobacco substitute materials, such as modified cellulosic materials, degraded or pre-pyrolyzed tobacco, and the like. Suitable materials are described, e.g., in U.S. Pat. U.S. Patent No. 4,347,855 to Lanzilotti et al., U.S. Patent No. 3,931,824 to Miano et al., and U.S. Pat. in U.S. Patent Nos. 3,885,574 and 4,008,723 to Bortwick et al. and in Sitting, Tobacco Substitutes. Noyes Data Corp. (1976). Other suitable combustible materials may be used as long as they burn long enough to mimic the burning time of a conventional cigarette and generate sufficient heat to be generated by the aerosol generating member from the aerosol generating material.

Preferred fuel elements normally contain combustible carbon materials obtained, for example, by pyrolysis or carbonization of cellulosic materials, such as wood, cotton, rayon, tobacco, coconut, paper, and the like. In most cases, combustible carbon is preferred due to its high heat generation capacity and because it produces only minimal amounts of incomplete combustion products. The carbon content of the fuel element is preferably about 20 to 40 weight percent or more.

The most preferred fuel elements are carbonaceous fuel elements (i.e., predominantly carbonaceous fuel elements) described and elucidated in co-pending patent applications No. 650,604, filed September 14, 1985, and No. 769,532, filed August 26, 1985. Carbonaceous fuel elements are particularly advantageous because they produce as little pyrolysis and incomplete combustion products as possible, produce little or no visible sidestream smoke, and as little as possible ash, and have good heat capacity. In particularly preferred embodiments, the aerosol delivered to the user i4 83020 does not have a significant mutagenic effect as measured by the Ames test. See Ames et al., Mut. Res. 31: 347-364 (1975); Nagas et al., Mut. Res. 42: 335 (1977).

Combustion additives or combustion regulators may also be added to the fuel to provide suitable combustion and glow properties. If desired, fillers such as diatomaceous earth and binders such as sodium carboxymethylcellulose (SCMC) may also be added to the fuel. Flavors and fragrances, such as tobacco extracts, may also be added to the fuel to add tobacco or other flavor to the aerosol.

The fuel element is equipped with several longitudinal passages. These pathways help to control the transfer of heat from the fuel element to the aerosol generating member, which is important to transfer sufficient heat to generate a sufficient amount of aerosol and also to avoid such a large amount of heat transfer that the aerosol generator disintegrates. In general, these pathways cause porosity and increase early heat transfer to the substrate by increasing the amount of hot gases entering the substrate. They also seek to increase the rate of combustion.

In general, a large number of passages or channels, e.g. 5-9 or more, and in particular the placement of the passages relatively far apart according to Figure 1A, provides a high convective heat transfer which results in a large aerosol formation. The large number of fairways also usually ensures easy ignition.

Good convection heat transfer creates a higher CO output to the mainstream. A smaller number of passages or a denser fuel cell can be used to reduce CO levels, but such changes generally make it more difficult to ignite the fuel cell and reduce the transfer of convective heat il 83020, thereby reducing the rate and amount of aerosol delivery. However, it has been found that, for example, in the closely spaced pathways shown in Figure 2A, where the pathways burn out or merge to form a single pathway at at least the ignition end, the amount of CO in combustion products is generally less than that formed using the same pathway arrangement. The optimum design, shape, and number of fuel cell pathways should be such that aerosol formation is uniform and abundant, ignition is easy, and CO is formed little. Various combinations have been studied for the placement / shape and / or number of pathways in the carbonaceous fuel elements used in various embodiments of the invention. In general, it has been found that fuel elements having about 5-9 passages relatively close to each other so that they burn out into one large passage at least at the ignition end of the fuel element appear to satisfy the requirements of the most preferred fuel element for use in this invention, especially with low carbon The fuel elements. However, it appears that this phenomenon also occurs with the use of various non-carbon fuel elements that can be used in the practice of the invention.

Variables that affect the rate of fuel element pathways merging when the element burns include the density and composition of the fuel element, the size, shape, and number of paths, the distance between the paths, and their placement. For example, when using a carbon fuel source with a density of 0.85 g / cm3 with seven lanes of about 0.5 mm, the lanes should be located within the inside diameter, i.e. the diameter of the smallest circle around the outer edge of the lanes between about 1.6 and 2.5 mm to converge into a single pathway during combustion. However, when the diameter of these seven passages is increased to about 0.6 mm, the combined inner diameter during combustion increases to about 2.1 to about 3.0 mm.

ie 83020

Another preferred fuel cell bus arrangement useful in the illustrated embodiments is the structure shown in Figure 3A, which has been found to be particularly advantageous in terms of low CO output and ease of ignition. In this preferred arrangement, the short portion at the ignition end of the fuel element is provided with a plurality of passages or channels, preferably about 5 to 9, which merge into a large cavity 97 extending to the mouth end of the fuel element. The multiple passages at the ignition end provide a large surface area that is advantageous in terms of ease of ignition and early aerosol production. The cavity may be about 30-95%, preferably more than 50% of the length of the fuel element, and ensures uniform heat transfer to the aerosol generating section and produces little CO in the main stream.

The aerosol generating member used in the practice of the invention is physically separate from the fuel element. By physically separate is meant that the substrate, container, or chamber containing the aerosol generating agents does not mix or form part of the combustible fuel element. As previously stated, this arrangement reduces or eliminates the thermal decomposition of the aerosol-forming material and the presence of sidestream smoke. Although the aerosol generating member is not part of the fuel, it is preferably in a conductive heat exchange ratio with the fuel element and is preferably located against or adjacent to the fuel element. The conductive heat exchange ratio is more preferably provided by a heat conductor portion, such as a metal tube or foil, which is preferably pulled back or separated from the ignition end of the fuel.

The aerosol generating member preferably includes one or more heat-resistant materials that carry or support one or more aerosol-forming agents. In this context, heat-resistant material means one that can withstand near-fuel conditions, for example 400 to 600 ° C.

II

17 83020 without decomposing or burning. The invention also encompasses other aerosol generating means, such as thermally breakable microcapsules or solid aerosol generating agents, provided that they are capable of releasing sufficient aerosol generating fumes that satisfactorily resemble tobacco smoke, but these are not preferred.

Heat-resistant materials used as a substrate or carrier for aerosol-forming materials are well known to those skilled in the art. Useful substrates should be porous and capable of binding the aerosol-forming material when not in use, and further should be able to release the aerosol-forming vapor when heated by the fuel element. In particular, the particulate substrates can be placed in a container, which is preferably formed of a conductive material.

Some useful heat-resistant materials include heat-stable adsorbing carbons, such as porous carbon grades. graphite, activated or inactive carbons and the like. Other suitable materials include inorganic solids such as ceramics, glass, alumina, vermiculite, clays such as bentonite and the like. Preferred carbon substrate materials are porous carbons such as PC-25 and PG-60 from Union Carbid and SGL carbon from Calgon.

A preferred alumina substrate for use in the aerolating material of the invention is SMR-14-1896 obtained from W.R. Grace & Co from Davidson Chemical Division and sintered at elevated temperatures, e.g., greater than about 1000 ° C, are washed and dried before use.

It has been found that suitable particulate substrates can also be formed from carbon, tobacco, or mixtures of carbon and tobacco into concentrated particles in a one-step process using a machine manufactured by Fuji Paudal KK of Japan and sold under the tradename "Marumerizer". This device is described in German Patent No. 1,294,351 and U.S. Pat. in U.S. Patent No. 3,277,520 (now republished under No. 27,214) and Japanese Patent Application Publication No. 8684/1967.

The aerosol generating member used in the invention is preferably located at a distance of at most about 40 mm, preferably at most about 30 mm and most preferably at most 20 mm from the ignition end of the fuel element. The length of the aerosol former may vary from about 2 mm to about 60 mm, preferably from about 5 to 40 mm, and most preferably from about 20 to 35 mm. The diameter of the aerosol generating member may vary between about 2 mm and 8 mm, preferably about 3 to 6 mm. If a non-particulate substrate is used, one or more holes may be formed in it to increase the surface area of the substrate and to increase airflow and heat transfer.

The aerosol-forming materials contained in the aerosol-forming material or materials of the invention must be able to form an aerosol at the temperatures prevailing in the aerosol-forming section when the combustible fuel element heats this part. These materials preferably consist of carbon, hydrogen and oxygen, but may contain other substances. Aerosol generating agents can be solid, semi-solid or liquid. The boiling point of the substance and / or mixture of substances can be as high as about 500 ° C. Substances with these properties include polyhydric alcohols such as glycerin and propylene glycol and aliphatic esters of mono-, di- or polycarboxylic acids such as methyl stearate, dodecanedioate, dimethyltetradodecanedioate and others.

Preferred aerosol-forming agents are polyhydric alcohols or mixtures of polyhydric alcohols. Particularly preferred aerosol generators are glycerin, propylene glycol, triethylene glycol or mixtures thereof.

The aerosol-forming agent may be dispersed in or within the aerosol-forming member in a concentration sufficient to saturate or spread on the substrate, carrier, or container. For example, the aerosol-forming agent can be used as a full-strength or dilute solution by dipping, spraying, vapor-separating, or the like methods. The solid aerosol-forming ingredients can be mixed into the substrate and evenly distributed therein prior to formation.

Although the loading of the aerosol-forming agent varies depending on the carrier and the aerosol-forming agent, the amount of liquid aerosol-forming agents generally ranges from about 20 mg to 120 mg, preferably from about 35 mg to 85 mg, and most preferably from about 45 mg to 65 mg. As much of the aerosol generator carried by the aerosol generating member as possible should be transferred to the user as a WTPM. Preferably, greater than about 2% by weight, more preferably greater than about 15% by weight, and most preferably greater than about 20% by weight of the aerosol former in the aerosol generating member is transferred to the user as a WTPM.

The aerosol-forming component may also contain one or more volatile flavoring agents, such as, for example, menthol, vanillin, artificial coffee, tobacco extracts, nicotine, caffeine, solutions, and other substances that impart flavor to the aerosol. It may also include other desired volatile solids or liquids. Alternatively, these optional agents may be placed between the aerosol generating member and the oral end, for example, as a separate substrate or as a container in the pathway leading from the aerosol generating member to the oral end or as a possible tobacco dose. If desired, these volatiles may be used in place of or as part of the aerosol-forming material so that the product imparts a flavor to the user of a non-aerosol or other material.

A particularly preferred aerosol-forming member comprises the above-mentioned alumina substrate containing spray-dried tobacco extract, tobacco flavor control agents such as Levuic acid, one or more flavoring agents, and an aerosol-forming material such as glycerin. This substrate can be mixed with compacted tobacco particles, such as those obtained with a "Marumerizer", and which particles can also be impregnated with an aerosol-forming material.

Products such as those set forth herein may be used or converted into usable drug delivery devices, and may provide volatile pharmacologically or physiologically active agents such as ephedrine, metaproterenol, tert-butaline, or the like.

As described in the illustrated embodiments, a smoking article using the aerosol-forming material of the present invention may also include a dose of tobacco on the back of the fuel element or a dose of tobacco-containing material that can be used to impart tobacco flavor to the aerosol. In these cases, the hot vapors sweep through the tobacco, extracting and vaporizing the volatile constituents in the tobacco without combustion or substantial pyrolysis. A preferred location for the tobacco dose is around the periphery of the aerosol generating member, as shown in Figure 3, whereby heat transfer to the tobacco is improved, especially in those embodiments where a heat conducting member or conductive container is used between the aerosol generating material and the annular tobacco layer. In these embodiments, the tobacco also acts as an insulating component of the aerosol former and helps to mimic the feel and aroma of a conventional cigarette. Another preferred location for the tobacco dose is within the aerosol generating member, where the tobacco or compacted tobacco particles li 2i 83020 can be mixed with or used in place of the substrate of the aerosol generating materials.

The tobacco-containing material may include any type of tobacco available to the professional, such as Burley, flue gas-cured tobacco, Turkish tobacco, blended tobacco, extruded or condensed tobacco blends, tobacco-containing sheets, and the like. The mixture of tobacco grades can be advantageously used to produce variations in aroma. The tobacco-containing material may also contain conventional tobacco additives such as fillers, peelers, reinforcing agents such as glass fibers, wetting agents and the like. Flavoring agents as well as flavoring agents may also be added to the tobacco material.

Preferably, the heat conducting member used is typically a metal (e.g., aluminum) tube, sheet, or foil having a thickness ranging from less than about 0.01 mm to about 0.2 mm or more. The thickness, shape, and / or type of conductive material (e.g., other metals or grafoil from Union Carbid) can vary to achieve virtually any desired degree of heat transfer. In general, the heat conductor section should be far enough behind it so as not to interfere with the ignition of the fuel element, but close enough to the ignition end to provide conductive heat transfer during the first and mid-suction operations.

As described in the illustrated embodiments, the heat conductor portion is preferably in contact with or over the rear of the fuel element and likewise is in contact with or over the aerosol generating member portion and far enough or apart from the ignition head to be spaced at least about 3 mm or more , preferably about 5 mm or more. The heat conductor portion preferably extends no more than about half the length of the fuel element. More preferably, the heat conductor portion 22 83020 enters or otherwise contacts the rear end of the fuel element by up to about 5 mm. Such preferred retracted parts do not prevent ignition or combustion of the fuel element. The preferred spaced conductor portions also help to extinguish the fuel as it burns to the point of contact of the conductor by acting as a heat sink, and such conductors do not protrude from the product even after the fuel has been used up.

The heat conductor part also preferably forms a conductive container which encloses the aerosol-forming materials. Alternatively, a separate conductive container may be included, especially in those embodiments where particulate substrates or semi-liquid aerosol-forming materials are used. Not only does the conductive container act as a container for aerosol-forming materials, it also improves heat distribution to the aerosol-forming materials and the preferred surrounding tobacco layer and prevents the aerosol-former from migrating to other ingredients in the product. The container also provides a means for controlling the pressure drop through the product by changing the number, size and / or position of the passages through which the aerosol former passes to the mouth end of the product. In addition, in those embodiments where a layer of tobacco is used around the circumference of the aerosol generating member, the container may be provided with circumferential openings or slots for regulating and controlling the flow of vapors through the tobacco. The use of a container also simplifies the manufacture of the product by reducing the number of parts and / or manufacturing steps required.

The insulating parts used can advantageously be formed as one flexible sheath of one or more layers of insulating material. This sheath is preferably at least 0.5 mm thick, more preferably at least 1 mm thick, and most preferably about 1.5 to 2 mm thick. The jacket preferably extends over the fuel element more than half its length. More preferably, it extends or covers all or part of the entire outer circumference of the fuel element and the aerosol generating member.

The insulating parts used are generally inorganic or organic fibers made of, for example, glass, alumina, silica, vitreous materials, lining, wool, carbon, silicon, boron, organic polymers, cellulosic materials, and the like, including mixtures of these materials. Likewise, non-fibrous insulating materials such as silica aerogel, perlite, glass and the like formed into mats, strips or other shapes can be used. Preferred insulating members are flexible to mimic the feel of a conventional cigarette. Preferred insulating materials should melt during use and have a softening temperature below about 650 to 700 *. Preferred insulation materials should also not burn during use. However, slow-burning coals and similar materials can be used. These materials act primarily as an insulating jacket, retaining and directing a substantial portion of the heat generated by the combustible fuel element to the aerosol generating member. As the insulation jacket heats up the burning fuel gesture. next to it, it can also conduct heat to a limited extent towards the aerosol generating part.

Currently preferred fuel cell insulation materials are ceramic fibers such as glass fibers. Two suitable glass fibers are available from Manning Paper Company, Troy, New York, under the tradenames Manniglas 1000 and Manniglas 1200. Preferred glass fiber materials have a low softening point, e.g., less than about 650 * using ASTM test method C 338-73. Preferred glass fibers are test materials manufactured by Owens-Cordning, Toledo, Ohio under the tradenames; 6432 and 6437, which have a softening point of about 640 * and which melt during use.

i 24 83020

Many commercially available inorganic fibers are made with a binder, e.g., PVA, that maintains the structure intact during processing. These binders give off a bitter taste when heated and should be removed, for example, by heating in air at about 650® for about 15 minutes before use. If desired, about 3% by weight of pectin can be added to the fibers to mechanically strengthen the sheath without causing a bitter taste.

Alternatively, the insulating material may be replaced in whole or in part by either loosely packed or tightly packed tobacco. The use of tobacco to partially or completely replace the insulating sheath further causes the aromas of the tobacco to shift into the main stream of aerosol and provide a tobacco-flavored side stream in addition to acting as an insulator. In preferred embodiments, where the tobacco layer surrounds the aerosol forming portion, the layer or sheath acts as a non-combustible insulator while imparting tobacco aromas to the main aerosol stream. In those embodiments where the tobacco surrounds the fuel, the tobacco is preferably consumed only to the extent that the fuel source is consumed, i.e., up to the point of contact between the fuel element and the aerosol generating member. This can be accomplished by squeezing the tobacco around the fuel element and / or using a conductive heat sink as in the embodiment shown in Figure 3. This can also be accomplished by treating the cigarette wrap and / or tobacco with materials that extinguish the tobacco at the point where it enters the aerosol generating member.

When the insulating part consists of fibrous materials other than tobacco, a closure part can be used between the insulating part and the mouth end of the product. One such closure member is an annular high density cellulose acetate sheath which abuts the fibrous insulating member and is sealed at both ends, for example with an adhesive, to prevent airflow from passing through the mandrel.

n 25 83020

In most embodiments, the fuel / aerosol generating member assembly is attached to a mouthpiece, such as foil-lined paper or cellulose acetate / plastic tubes shown in the figures, although the mouthpiece may be formed separately, for example in the form of a cigarette holder. This part of the product forms a pathway that directs the vaporized aerosol-forming agents into the user's mouth. It is preferably about 35 to 50 mm in length or more and therefore also keeps the hot cone of fire away from the user's mouth and fingers and allows the hot aerosol sufficient time to form and cool before it enters the user.

Suitable mouthpieces should be inert to the aerosol-forming agents, may have a water- or liquid-tight inner layer, should minimize aerosol loss due to condensation or filtration, and should be able to withstand the temperature at the interface between them and other parts of the product. Preferred mouthpieces include a cellulose acetate tube used in many of the forms of filtration shown, which acts as a flexible outer member and helps to mimic the feel of a conventional cigarette at the mouth end of the product. Other suitable mouthpieces will be apparent to those skilled in the art.

Mouthpieces useful in products such as those shown may include an optional "filter" used to impart the appearance of a conventional filter cigarette to the product. Such filters include low efficiency cellulose acetate filters and hollow or flap plastic filters made of, for example, polypropylene. These filters do little to interfere with aerosol delivery.

The product may be coated along its entire length or any part thereof may be coated with cigarette paper. Preferred papers are those that do not ignite at the fuel cell end 26 83020 during combustion of the fuel cell. In addition, the paper should have controlled boiling properties and should form a gray, cigarette-like ash.

In filter forms using an insulating jacket, in which the paper burns away from the jacketed fuel element, maximum heat transfer is achieved due to the fact that the air flow to the fuel source is not restricted. However, papers may be used which remain completely or partially intact when exposed to the heat from the combustible fuel element. Such papers provide a limited flow of air to the combustible fuel element, thereby helping to control the temperature at which the fuel element burns, thereby controlling or directing heat transfer to the aerosol generating member.

In order to reduce the combustion rate and temperature of the fuel element and thus to maintain a low CO / COa ratio, non-porous or zero-porous paper which is treated to be slightly porous and in the case of, for example, non-combustible mica paper can be used as the top layer. with lots of holes. Such paper controls heat generation, especially during mid-suction (i.e., suction 4-6).

From the aerosol generating portion to the mouth end, non-porous paper can be used to maximize the aerosol inlet that would otherwise be diluted by radial (i.e., exterior) air penetration through the product.

Such papers are known in the cigarette paper industry and combinations of these papers can be used to produce various effects. Preferred papers used in the products of the present invention include Ecusta 01788 and 646 n \ 27 83020 coating paper manufactured by Ecusta, Pisgah Forest, North Carolina and Kimperly-Clark's KC-63-5, P 878-5, P 878-16- 2 and 780-63-5 papers.

Preferred embodiments are capable of delivering at least 0.6 mg of aerosol measured as total wet particulate matter (WTPM) during the first three puffs when performing smoking under FTC smoking conditions (FTC smoking conditions comprise two second puffs (35 ml total volume) separated by 58 second puffs). Even more preferred embodiments are capable of delivering 1.5 mg or more of aerosol in the first three aspirations. Most preferred embodiments deliver 3 mg or more of aerosol on the first three puffs when performing smoking under FTC smoking conditions. Further preferred embodiments produce an average of at least about 0.8 mg of total wet particulate matter per puff for at least about six puffs, preferably for at least about 10 puffs under FTC smoking conditions.

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Claims (10)

28 83020 An aerosol-forming material for use in a smoking article, the material comprising an alumina substrate supporting an aerosol-forming agent, characterized in that the alumina substrate contains alumina sintered at a temperature above 1000 ° C. An aerosol-forming material according to claim 1, characterized in that said substrate supports an aerosol-forming agent consisting of at least carbon, hydrogen and oxygen. Aerosol-forming material according to claim 1 or 2, characterized in that said substrate supports a volatile tobacco flavor. Aerosol-forming material according to Claim 1, 2 or 3, characterized in that the sintered alumina is washed and dried before use. Aerosol-forming material according to any one of the preceding claims, characterized in that said aerosol-forming agent contains polyhydric alcohols. Aerosol-forming material according to claim 5, characterized in that said polyhydric alcohol comprises glycerin and / or propylene glycol and / or triethylene glycol. Aerosol-forming material according to claim 3, characterized in that said tobacco flavoring agent contains tobacco extract. Il 29 83020 Aerosol-forming material according to any one of the preceding claims, characterized in that said substrate further supports a tobacco flavoring agent. Aerosol-forming material according to one of the preceding claims, characterized in that the substrate carries a flavoring agent. An aerosol-forming material according to claim 2, characterized in that said aerosol-forming agent comprises glycerin and in that said alumina disubstrate comprises a tobacco extract and one or more flavoring agents. 30 83020