NO167952B - BEAUTY ARTICLE WITH IMPROVED AGENTS FOR DELIVERING FLAVORS. - Google Patents

Description

The present invention relates to a smoking article comprising a fuel element, a physically separate aerosol-forming device containing a substrate material containing at least one aerosol-forming material, and a nozzle for releasing the aerosol which the aerosol-forming device provides to the smoker, and which preferably contains a filter plug at the mouth end thereof. As used herein, the term "smoking article" includes cigarettes, cigars, pipes and other smoking products that produce an aerosol such as smoke. More particularly, the present invention is preferably directed to a carbon-filled sheet, which preferably contains tobacco, the sheet being used as at least part of the nozzle on such articles to carry flavourings, especially highly volatile flavorings such as menthol.

Cigarettes, cigars and pipes are the most popular forms of smoking articles. Many smoking products and smoking articles have been proposed over the years as improvements to, or alternatives to, these popular forms of smoking articles, particularly cigarettes.

Many have e.g. proposed tobacco substitute smoking substances. See e.g. U.S. Patent No. 4,079,742 to Rainer et al. Two such substances, cytrel and NSM, were introduced in Europe in the 1970s as partial tobacco substitutes, but did not achieve any commercial success over time.

Many others have proposed smoking articles, particularly cigar smoking articles, based on the generation of an aerosol or a vapor. See e.g. the background technology referenced in the U.S. Patent No. 4,714,082 to Banerjee et al.

To the knowledge of the present inventors, none of the foregoing smoking articles has ever achieved any significant commercial success, and none has ever been marketed on a large scale. The absence of such smoking articles on the market is believed to be due to several different reasons, including insufficient aerosol generation, both initially and during the lifetime of the product, poor taste, off-flavor due to thermal degradation of the smoke generator and/or flavoring agents, the presence of significant pyrolysis products and side stream smoke, and not a pretty appearance.

Thus, despite several decades of interest and effort, there is still no smoking article on the market that provides the benefits, advantages and pleasures associated with smoking, without delivering significant amounts of incomplete combustion and pyrolysis products.

More recently, however, in European Patent Publication Nos. 0174645 and 0212234 and U.S. Pat. Patent No. 4,714,082, issued to R.J. Reynolds Tobacco Co., described smoking articles, particularly cigarette smoking articles, which are capable of providing the advantages, benefits and pleasures associated with smoking, without burning tobacco or emitting significant amounts of incomplete combustion or pyrolysis products. The improved device for dispensing flavors according to the present invention is particularly suitable for use with such articles.

Mentholated smoking articles represent a significant share of the total market. In reality, nearly 1/3 of all cigarettes produced are mentholated to some degree. However, one of the significant problems with menthol and other volatile and semi-volatile flavorings used in smoking articles is that the flavorings usually transfer to other components of the article. Such migration is well documented in the literature. See e.g. Brozinski, M. et al., Beitrage zur Tabakforschug International 6, 124-130 (1972); Curran, J.G., Tobacco Science 16, 40-42 (1972); and Reihl, T.F. et al., Tobacco Science 17, 10-11 (1973).

In cigarettes, this migration takes place whether the flavoring substances are incorporated in the tobacco, the filter, the wrapping materials or on the packaging materials (e.g. mentholated foil). The end result of all such applications is the same. During storage, the result is an equilibrium level of flavourings, so that the flavorings travel through the entire smoking article and the associated packaging. The degree of migration depends on, among other things, the flavoring's vapor pressure, its solubility in the various components of the article, environmental conditions including temperature and relative humidity, the resistance to migration of the various materials (e.g. tobacco, wrapping, filter material, glue , etc).

Several attempts to solve migration-related problems have been made, but have achieved limited success. E.g. various chemicals such as chemically bound non-volatile substances have been used to reduce the migration (eg beta-cyclodextrin menthol complexes, glucosides of menthol, menthol amides, esters, etc.). See e.g. U.S. patent no. 3,426,011 to Parmerter et al. and 3,344,796 to Yamaji et al. Generally, all these compounds have limited application, due to costs and because the emitted smoke gives a bad taste perception.

Others have studied the application of so-called microencapsulated flavorings in various places in the smoking article. See e.g. U.S. Patent Nos. 3,550,598 and 3,540,456 to McGlumphy et al., Swiss Patent No. 475,418 to Baumgartner Papiers S.A. and Dutch Patent No. 8201585 to Dowve Egbert's Koninklij-ke. Still others have enclosed volatile flavors in polymer systems such as linear low density polyethylene and inorganic filters e.g. CaC03 , aluminum oxides, etc, and placed these substances in the form of pellets or strings or particles in the filter systems or wrapping systems. The problems with this approach are that the migration still takes place (admittedly in a controlled manner), that the amount of flavorings required with such substances is often very large and cost prohibitive, and that the average rate of release of the flavorings is low, usually between 1-18 wt. -% based on applied level.

The use of carbon in various cigarette components has also been suggested. In particular, carbon has been used in the wrapping systems, as filler material, and in the filter systems for the reduction of smoke constituents in the gas phase, as well as for the introduction of flavorings into the cigarette. See e.g. U.S. Patent Nos. 2,063,014 to Allen, 3,744,496 to McCarty et al., 3,902,504 to Owens et al., 4,505,202 to Cogbill et al., and 4,225,636 to Cline et al. However, carbon, and especially activated carbon, has not found significant commercial use as a carrier for flavoring agents such as menthol, as among other things activated carbon absorbs the majority of the menthol before it can be released to the smoker. To compensate for this phenomenon, the carbon material is usually saturated with flavoring f. As noted above, however, this results in undesirable migration of the flavoring to other components of the smoking article. See e.g. U.S. Patent No. 3,236,244 to Irby et al. which describes the use of activated carbon both to remove unwanted constituents from the smoke as well as to introduce flavoring agents to it.

U.S. patent no. 3,972.3 35 to Tigglebeck et al. know-know this problem. Tigglebeck reveals blocking of the small pores in activated carbon with a pore modifying agent such as sucrose. The pore modifying agent is disclosed for use in such amounts that the less retentive portions of the activated carbon are not blocked, but remain available for adsorption of the flavoring. The purpose of this should be to increase the durability of the smoking article by reducing the migration of the flavoring and still allow effective release of the flavoring during smoking. However, significant migration seems to occur, more than around 40%. See Example I in columns 5-6. Accordingly, carbon filters or carbon recirculators have not generally been recommended for mentholated smoking articles.

The present invention provides a smoking article of the initially mentioned kind in which the nozzle contains a carbon-filled sheet material containing at least one flavouring. The article can emit menthol and other volatile flavorings along with the aerosol, without any significant migration of the flavoring to the fuel element or other components of the smoking article. The carbon-filled foil material is placed in a non-burning part of the smoking article, e.g. in any part of the article which is located longitudinally behind the fuel element and separate from the fuel element. However, it preferably takes the form of a cylindrical segment or a plug placed between the aerosol generating device and the mouth end of the smoking article.

Preferably, the smoking articles using the improved flavor delivery device are cigarettes, which use a short, ie less than about 30 mm long fuel element preferably of carbon. Preferably, the aerosol-generating device is located in the longitudinal direction behind the fuel element, and is in a conductive heat exchange relationship with the fuel element. The nozzle preferably comprises a filter segment, preferably one with a relatively low efficiency, in order to avoid affecting the release of the aerosol produced by the aerosol generating device. The device for dispensing flavors according to the present invention comprises a carbon-filled sheet material which can be used in any of the non-burning parts of the smoking article, i.e. in any of the components located longitudinally behind or otherwise separated in relation to to the fuel element. Preferably, it is placed between the filter segment and the aerosol generating device. In certain preferred embodiments, the flavoring device comprises a segment of rolled, folded or gathered carbon-filled sheet of tobacco paper approximately 5-15 mm long.

It has been found that the improved flavoring device according to the present invention helps to reduce the migration of flavorings, especially menthol and other volatile flavorings, to other components of the smoking article or the equipment used to manufacture such articles. Reducing the migration to the fuel source is particularly important because of the undesirable deviation in taste which may be the result of thermal decomposition and pyrolysis of the flavor substances present in the burning fuel element. This reduction in migration also helps to increase the shelf life of smoking articles containing volatile flavorings such as menthol. It has also been found that the flavoring substances are released easily and evenly from the carbon-filled sheet material during smoking, when aerosol and hot gases from the aerosol-generating device pass over or through the sheet material. It is believed that slightly higher than normal aerosol temperatures, approximately 150°C immediately downstream of the aerosol generating device, help to deliver consistent amounts of the flavoring over the lifetime of the smoking article. Additionally, smoking articles that utilize the carbon-filled sheet material as a component of the mouthpiece provide such reduced migration and uniform release of flavors without significant reduction in the release of other aerosol components, e.g., glycerin, water, etc. In other words, the filter efficiency of the carbon-filled sheet material is significantly lower than the efficiency of other cigarette filter materials, such as cellulose acetate webs. This is important for maintaining the desired release of the aerosol produced by the smoking articles according to the present invention.

The preferred carbon-filled sheet material of the present invention also acts as a heat reservoir, which helps to reduce the aerosol temperature perceived by the smoker, and also helps to prevent unwanted degradation or melting of the filter material.

Preferred smoking articles employing the improved flavor delivery device of the present invention are capable of delivering at least 0.6 mg of aerosol, measured as total wet particulate matter (WTPM), in the first 3 puffs when smoked under TFC smoking conditions, which consist of 35 ml puffs of two second duration, separated by a 58 second break. More preferably, embodiments of the invention are capable of delivering 1.5 mg or more of aerosol in the first 3 puffs. Most preferably, the embodiment of the invention is capable of delivering 3 mg or more of aerosol in the first 3 puffs when smoked under FTC smoking conditions. Moreover, preferred embodiments of the invention emit an average of at least about 0.8 mg WTPM per puffs below at least about 6 puffs, preferably at least about 10 puffs, under FTC smoking conditions.

In addition to the foregoing advantages, preferred smoking articles of the present invention are capable of producing an aerosol that is chemically simple, consisting essentially of air, oxides of carbon, water, the aerosol former, any desired flavoring or other desired volatile substances, and trace amounts of other substances. The aerosol also preferably has no significant mutagenic activity measured by the Ames test. In addition, preferred articles can be made essentially ash-free, so that the user does not need to remove ash during use.

As used herein, and for the purposes of this application only, "aerosol" is defined to include vapors, gases, particles and the like, both visible and invisible, and especially those components perceived by the user to be "smoke-like", produced by the action of heat from the burning fuel element on substances contained in the aerosol generating device, or elsewhere in the article.

As used herein, the term "heat conductive exchange ratio" is defined as a physical arrangement of the aerosol generating device and the fuel element whereby heat is transferred by conduction from the burning fuel element to the aerosol generating device substantially during the burning time of the fuel element. Conductive heat exchange conditions can be achieved by placing the aerosol-generating device in contact with the fuel element and thus in the immediate vicinity of the burning part of the fuel element, and/or by utilizing a conductive part to transfer heat from the burning fuel to the aerosol-generating device. Preferably, both methods are used to produce conductive heat transfer.

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

As used herein, the term "insulating part" refers to all materials that act primarily as insulators. Preferably, these materials do not burn in use, but may include slow burning carbon and similar materials, as well as materials that melt in use, such as low temperature grades of glass fibers. Suitable insulators have a thermal conductivity in g-cal(sec) (cm<2>) ("C/cm), of less than about 0.05, preferably less than about 0.02, most preferably less than about 0.005. See Hackh's Chemical Dictionary 672 (fourth edition, 1969) and Lange's Handbook of Chemistry 10, 272-274 (eleventh edition, 1973).

Smoking articles employing the improved flavor delivery device in accordance with the present invention are described in greater detail in the accompanying drawings and detailed description of the invention as follows: Figure 1 is a longitudinal section of a preferred cigarette utilizing the improved delivery device of flavors in accordance with the present invention. Figure IA illustrates, from the ignition end, a configuration

tion of the passages in a preferred fuel element.

Figure 2 illustrates the results of a migration study of preferred cigarettes with and without the carbon-filled sheet material according to the present invention. Figure 3 schematically illustrates a method for shaping the carbon-filled sheet material into a cylindrical segment in the form of a filter plug. Figure 3A illustrates a double-conical system used to collect or fold the material into the shape of a filter plug.

According to the present invention, an improved device for dispensing flavoring substances for use in smoking articles is provided. The device for dispensing flavoring substances is particularly suitable for smoking articles having a combustible small fuel element, a physically separate aerosol generating device, and a separate nozzle such as those described in the above-referenced EPO publications No. 174,645 and 212,234.

Usually, the improved facility includes

delivery of flavorings a carbon-filled sheet material typically made by adding carbon (activated, unactivated or mixtures thereof) to common paper pulp such as wood pulp or flax fiber pulp and/or pulp of tobacco stalks or trunks. This

material is then formed into a sheet material using conventional papermaking techniques.

Although the porosity of the carbon-filled sheet material may vary over a wide range, it preferably has an internal porosity between about 100 and 250 CORESTA units, and a net porosity greater than about 150 CORESTA, preferably 300 and 30,000 CORESTA. The net porosity is achieved by producing holes by mechanical, electrostatic or laser devices, and/or by slitting the sheet material. Sheet materials having a porosity in this range are particularly advantageous as they allow greater amounts of flavoring to be absorbed into the carbon-filled sheet material by adsorptive and/or absorptive mechanisms, and because the total surface area of the flavoring delivery device can be significantly increased without increasing filtration efficiency for the carbon-filled sheet material.

The carbon content of the sheet material can vary over a wide range depending on several factors, including the type and amount of carbon and/or flavor used, the location of the carbon-filled sheet material in the smoking article, and the shape or configuration of the sheet material. Generally, the carbon content can lie in the range between approximately 5 and 75% by weight of the sheet material, preferably between approximately 10-40%, most preferably between approximately 15-30%. Although larger amounts of carbon can be used, sheets containing more than about 75% by weight carbon will lead to limitations in papermaking as well as limitations in the properties of the paper, e.g. tensile strength, heavy dusting and related problems.

Although either activated or unactivated carbon can be used as the carbon component in the sheet material, activated carbon is preferred. As will be appreciated by those skilled in the art, there are a number of types of activated carbon that are commercially available and that can be used in accordance with the principles of the present invention. It is e.g. charcoal-based, wood-based and coconut shell-based activated carbon types available from several sources. A particularly preferred activated carbon, a coconut shell based carbon, is PCB manufactured by Calgon Carbon Corporation, Pittsburgh, Pennsylvania. This special carbon can be pulverized into several different sizes. Although almost any size of particles can be used in the sheet material of the present invention, preferred sizes are between about 250 and 600 U.S. mesh.

As the skilled person will understand, other adsorptive/absorptive substances can be incorporated into the sheet material instead of, or together with, the carbon component of the sheet material. Such substances include charcoal, silica gel, zeolites, perlite, sepio-lite, activated alumina, magnesium silicates and the like.

As noted above, the carbon-filled sheet material can be made using ordinary paper pulp. Preferably, it is made from a mixture of wood pulp and a pulp made from tobacco stalks or trunks. The carbon component of the sheet material is usually added to a slurry of the pulp materials, and the mixture formed into a sheet using conventional papermaking equipment. The preferred sheet material is a carbon filled tobacco paper made by adding the desired amount of carbon to the tobacco paper pulp used to make a Kimberly-Clark tobacco paper designated P144-185-GAPF. Unmodified P144-185-GAPF comprises approximately 60% tobacco mainly in the form of smoke-ripened/burley tobacco stems and 35% leaf pulp (based on dry weight of the materials). The moisture content in the unmodified sheet-like material is preferably between approximately 11 and 14%. The material has a dry tensile strength of about 1,600 to about 3,300 gm/inch (630-1,300 g/cm), and a dry basis weight of about 38 to about 44 g/m<2>. The material is made using a conventional papermaking type process, including the addition of about 2% glycerin or other wetting agent, about 1.8% potassium carbonate, about 0.1% flavorings and about 1% of a commercial sizing agent. The sizing agent is commercially available as Aquapel 360XC Reactive Size from Hercules Corp., Wilmington, Delaware.

Flavorings can be incorporated into or onto the carbon-filled sheet material by any of several means such as spraying, dipping, printing, vapor deposition, and the like. Preferably, the flavoring is added to the sheet by a steam application technique. Vapor deposition is a technique that typically involves heating the flavor to a point where it is highly volatile, and passing or contacting the carbon-filled sheet material with the vapors for a time sufficient to allow the desired amount of flavor to be absorbed/adsorbed onto the carbon-filled the sheet material. A preferred application technique, referred to as inner blade transfer, involves contacting the carbon-filled sheet material with an inner blade material. The inner sheet material may be any of several materials, such as a heavy plug wrap, provided that its affinity for the flavoring agent is less than the affinity of the carbon filled sheet material of the present invention.

Another preferred method for adding flavorings to the sheet material comprises printing the flavoring on the sheet material. Typically, printing involves passing the sheet material over a drum that rotates through a bath containing the flavors of interest.

Further other methods of adding flavors to the carbon either before or after it is incorporated into the sheet material will be readily understood by the skilled person.

Any number of flavoring agents may be used in the practice of the present invention, such as menthol, vanillin, artificial coffee, tobacco extracts, nicotine, nicotine salts, caffeine, spirits, cocoa butter, and other flavoring agents to the aerosol produced by the smoking article. Other flavorings that may be used include those listed in Leffingwell et al., "Tobacco Flavorings for Smoking Products", R.J. Reynolds Tobacco Company, Winston-Salem, North Carolina

(1972).

The amount of flavorings impregnated in or otherwise carried by the sheet material can vary over a wide range depending on the type of flavoring, the amount of flavoring, the carbon content of the sheet material, the activity of the carbon, the location of the sheet material in the smoking article, the manner in which the carbon filled sheet material is rolled , folded, gathered or otherwise placed in the smoking article and the like. For example, when a strong flavoring agent such as alpha ionone is used, it may be desirable to have amounts as low as 0.00001% by weight of the sheet material. When menthol is the flavouring, the amount can vary between 0.001% up to saturation. In preferred smoking articles, such as those described in Example I, the amount of menthol incorporated into the carbon-filled sheet material is between about 3 to 6%, most preferably between about 4 to 5%.

As noted above, in certain preferred embodiments the carbon filled sheet material is positioned between the aerosol generating device and a mouth end filter, and is preferably in the form of a cylindrical filter plug. The sheet material can be formed into a cylindrical or other suitable shape by common filter plug forming techniques, such as common plug formers used to make cellulose acetate straw.

FIG. 3 illustrates a device for forming the carbon-filled sheet material in the form of a filter plug. As shown schematically in FIG. 3, a roll 53 of flavored carbon-filled sheet material 50 is unwound and drawn into a forming tapering cone 54 which "gathers" or "folds" the sheet material 50 into a cylindrical shape suitable for feeding into the cylindrical plug maker. Two or more carbon-filled sheets with varying properties, e.g. with different carbon content, flavourings, etc. can be processed separately or at the same time to produce a flavoring delivery device with several segments or several layers. This forming cylinder 55 receives a wrap of paper 56, and the combination is cut to desired lengths 57 with the blade 58. Before the wrapping paper 56 reaches the garnish, a continuous string of adhesive is applied to one edge thereof via an applicator. As these components pass through the garnish, the forming cylinder 55 is further compressed into a rod of cylindrical cross-section, while simultaneously being enclosed by the paper 56. When the adhesive strand contacts the lapped portion of the wrapped rod, it is sealed by means of a sealing rod. This endless cylindrical rod is then cut into lengths 57 using the knife 58.

Alternatively, it is preferred to use the double cone system illustrated in Figure 3A instead of the single cone 54. This system comprises a cone inside a cone as preforming apparatus. The carbon-filled sheet material is fed into the annular space between the cones in a substantially tension-free state, so that the sheet material at the inlet point is wrapped around the radial part of the inner cone. The cones can be moved relative to each other to achieve the desired smoothness and firmness of the cylindrical segment.

Although not essential to making acceptable cylindrical segments of flavored carbon-filled sheet material, the sheet material is suitable for flavoring prior to being formed into a cylindrical segment. Two such treatments, illustrated in Fig. 3, may comprise a pair of rollers 59 with grooves which are used for shrinking, and a liquid applicator 60 which is used for surface treatment of the sheet material with e.g. menthol, glycerin or other flavorings or humectants.

In preferred embodiments where the carbon-filled sheet material is placed between the aerosol-generating device and the mouth-end filter in the form of a cylindrical segment or a plug, the length of the flavored carbon-filled sheet segment will usually vary with the type and amount of flavor used. For cigarettes using the preferred nozzle described in Example I, below, the segment of the carbon-filled sheet material is usually between about 5 and 30 mm long, preferably between about 5 and 15 mm long, and most preferably about 10 mm long.

Seen from an application and/or aesthetic point of view, the firmness of the flavored carbon-filled sheet segment used in accordance with the present invention can vary greatly without substantially affecting the aerosol delivery to the user. However, it is desirable to have a segment that feels and has the firmness of a cigarette using ordinary cellulose acetate filters.

The total pressure loss for smoking articles using the improved flavor delivery device of the present invention is preferably the same as or less than the pressure loss for other cigarettes. The pressure loss for the carbon-filled sheet material and the filter material in the nozzle itself will vary in accordance with the pressure loss for the front part of the smoking article. For preferred smoking articles, such as those described in Example I below, the pressure loss will usually be less than the pressure loss of conventional filter plugs, usually in the range between about 0.1 and 6.0 cm water column/cm filter length, preferably in the range between about 0 .5 and approximately 4.5 cm water column/cm filter length, and most preferably in the range between approximately 0.7 and approximately 1.5 cm water column/cm filter length. The filter pressure loss is the pressure loss in centimeters of water column when 1050 cm<3>/min. air is led through a filter plug. These pressure losses can be normalized to the unit length of the filter plug by dividing by the actual filter length.

Preferred smoking articles that use the improved device for dispensing flavors in accordance with the present invention are described in the following patent applications:

which disclosures are hereby incorporated by reference.

Such a preferred smoking article is shown in Figure 1 which is attached to this description. With reference to Figure 1, there is shown a cigarette which has a small fuel element 10 of carbon, with several passages 11 through it, preferably about thirteen arranged as in Figure IA. Another preferred embodiment uses a fuel element having eleven holes in the same manner as the arrangement of Figure IA, but with only five central passages made in a '^" pattern. This fuel element is made of an extruded mixture of carbon (preferably of carbonized paper ), sodium carboxymethyl cellulose (SCMC) binder, K2CC>3 and water as described in the above-referenced patent applications and EPO applications.

The periphery 8 of fuel element 10 is surrounded by an elastic sheath of insulating fibers 16, such as glass fibers.

A metallic capsule 12 overlaps a portion of the mouth end of the fuel element 10 and encloses the physically separate aerosol generating device containing a substrate material 14 containing one or more aerosol generating substances. The substrate can be in particle form, in the form of a rod, or in other forms as detailed in the above-referenced patent applications.

The capsule 12 is surrounded by a roll of tobacco filler 18.

Two slot-like passages 20 are found in the mouth end of the capsule in the center of the crimped tube.

At the mouth end of the tobacco roll 18 is a mouthpiece 22, which preferably comprises a cylindrical segment of a flavoring-added carbon-filled sheet material 24 according to this invention, and a segment of non-woven thermoplastic fibers 26 through which the aerosol passes to the user. The article or parts thereof are wrapped with one or more layers of cigarette paper 30-36.

As noted above, the carbon-filled sheet material may be placed within one or more of the other non-burning components of the smoking article. E.g. the carbon-filled sheet material may be cut up and included as all or part of the tobacco roll, or it may be used as one or more of the non-burning wraps used to bind together the various components of the smoking article.

When the aforementioned cigarette is lit, the fuel element will burn, and generate the heat used to volatilize the tobacco flavor material and any additional aerosol-forming substance or substances in the aerosol-generating device and the tobacco roll. Because the preferred fuel element is relatively short, the hot burning cone of fire is always close to the aerosol generating device, which maximizes heat transfer to the aerosol generating device and the tobacco roll, and the resulting production of aerosol and tobacco flavors especially when the preferred heat conducting portion is employed. The hot gases, the aerosol and the flavoring substances from the aerosol-generating device and the tobacco roll, heat up the flavoring-added carbon-filled sheet material according to the invention, which emits the flavorings therefrom.

Due to the small size and burning characteristics of the fuel element, the fuel element typically begins to burn over substantially its entire exposed length within a few puffs. The part of the fuel element close to the aerosol generator therefore heats up quickly, which significantly increases the heat transfer to the aerosol generator and the tobacco roll, especially during the early and middle puffs. Because the preferred fuel element is so short, there is never a long section of non-burning fuel acting as heat storage, as was common in earlier thermal aerosol articles. This in turn increases the temperature to which the flavored carbon-filled sheet material is exposed, which, it is believed, increases the release of flavorings from the carbon component of the sheet. Because the aerosol-forming and tobacco flavoring substances and flavoring agents on the carbon-filled sheet material are physically separate from the fuel element, they are, however, exposed to significantly lower temperatures than those produced by the burning fuel, which thereby reduces the possibility of thermal decomposition of flavoring substances and aerosol-forming substances.

In preferred embodiments, the short carbon fuel element, the heat conducting portion, and the insulating portion cooperate with the aerosol generator and tobacco roll to provide a system capable of producing significant amounts of aerosol, tobacco flavoring, and flavoring agents from the carbon-filled sheet material at virtually every single puff The close proximity between the fire cone and the aerosol generator and the tobacco roll after a few puffs, together with the insulating part, results in high heat output both during the puff and during the relatively long period of residence between puffs.

Generally, the combustible fuel elements that can be used in preferred embodiments have a diameter no larger than the diameter of a cigarette (ie, less than or equal to 8 mm), and are usually less than about 30 mm long before smoking. Advantageously, the fuel element is about 15 mm or less in length, preferably about 10 mm or less in length. Advantageously, the diameter of the fuel element is between approximately 2 and 8 mm, preferably approximately 4 to 6 mm. The density of the fuel elements used herein can usually lie in the range from about 0.7 g/cm<3> to about 1.5 g/cm<3>. Preferably, the density is greater than about 0.85 g/cm<3>.

The preferred material used to make the fuel elements is carbon. Preferably, the carbon content of these fuel elements is at least 60 to 70%, most preferably about 80% or more by weight. High carbon fuel elements are preferred because they provide minimal pyrolysis and incomplete combustion products, little or no visible sidestream smoke, and minimal ash, and have high heat capacity. Fuel elements with low carbon content, e.g. about 50 to 60% by weight, however, can be used, especially where a smaller amount of tobacco, tobacco extract, or a non-burning inert filler is used. Preferred fuel elements are described in greater detail in the above-referenced patent applications and EPO publications.

The aerosol generating devices used to practice this invention are physically separate from the fuel element. By physically separate is meant that the substrate, container or chamber containing the aerosol-forming material is not mixed with, or part of, the fuel element. This arrangement helps to reduce or eliminate thermal decomposition of the aerosol-forming substance and the presence of sidestream smoke. Even if it is not part of the fuel element, the aerosol generating device will preferably butt against, be connected to, or otherwise be close to the fuel element so that the fuel and the aerosol generating device are in a conductive heat exchange relationship. Preferably, the conductive heat exchange ratio is achieved by providing a heat conductive member, such as a metal foil, withdrawn from the ignition end of the fuel element, which effectively conducts or transfers heat from the burning fuel element to the aerosol generating device.

The aerosol generating device is preferably separated by no more than 15 mm from the ignition end of the fuel element. The aerosol generating device can vary in length from approximately 2 mm to approximately 60 mm, preferably from approximately 5 mm to 40 mm, and most preferably from approximately 20 mm to 35 mm. The diameter of the aerosol-generating device can vary from about 2 mm to about 8 mm, and is preferably from about 3 to 6 mm.

Preferably, the aerosol-generating device comprises one or more thermally stable substances containing one or more aerosol-forming substances. As used herein, a "thermally stable" material is a material capable of withstanding the high, albeit controlled, temperatures, e.g. from about 400°C to about 600°C, which can eventually occur close to the fuel, without significant degradation or burning. The use of such materials is believed to help maintain the simple "smoke" chemistry of the aerosol, as evidenced by the lack of Ames Test Activity in the Preferred Embodiments Although not preferred, other aerosol-generating devices, such as heat-exploded microcapsules, or solid aerosol-forming substances, are within the scope of this invention, provided they are capable of releasing sufficient aerosol-forming vapors.

Thermally stable substances which can be used as a carrier or substrate for the aerosol-forming substance are well known to specialists in the technology. Usable carriers should be porous, and must be capable of retaining an aerosol-forming compound, and releasing a potential aerosol-forming vapor upon heating by the fuel. Useful thermally stable substances include adsorbent carbons, such as porous grade carbons, graphite, activated or non-activated carbon types, and the like, such as PC-25 and PG-60 available from Union Carbide Corp., as well as SGL carbon, available from Calgon Carbon, Corp. Other suitable substances include inorganic substances, such as ceramic substances, glass, alumina, vermiculite, clay such as bentonite or mixtures thereof. Carbon and alumina substrates are preferred.

A particularly useful alumina substrate is an alumina with a high specific surface area (about 280 m<2>/g), such as the grade available from the Davison Chemical Division of W.R. Grace & Co. under the designation SMR-14-1896. This alumina (-14 to +20 U.S. mesh) is preferably sintered for about one hour, at an elevated temperature, e.g. higher than 1000°C, preferably from about 1400°C to 1550°, followed by suitable washing and drying, before use.

The aerosol-forming substance or substances used in the articles according to the present invention must be able to form an aerosol at the temperatures present in the aerosol-generating device when heated by means of the burning fuel element. Such substances are preferably non-tobacco, non-aqueous aerosol-forming substances and are composed of carbon, hydrogen and oxygen, but they may include other substances. Such substances can be in solid, semi-solid or liquid form. The boiling or sublimation point of the substance and/or mixture of substances can lie in the range up to around 500°C. Substances having these properties include: polyhydric alcohols, such as glycerin, triethylene glycol and propylene glycol, as well as aliphatic esters of mono-, di- or polycarboxylic acids, such as methyl stearate, dimethyl dodecanedioate, dimethyl tetradecanedioate and others.

The preferred aerosol-forming substances are polyhydric alcohols or mixtures of polyhydric alcohols. More preferred aerosol formers are selected from glycerin, triethylene glycol and propylene glycol.

When a substrate material is used as a carrier, the aerosol-forming substance can be dispersed by known techniques on or in the substrate in a concentration sufficient to penetrate or coat the material. E.g. the aerosol-forming substance can be used in full strength or in diluted solution by dipping, spraying, steam application or similar techniques. Solid aerosol-forming components can be mixed with the substrate material and distributed evenly therein prior to the formation of the final substrate.

While the amount of the aerosol-forming substance will vary from carrier to carrier and from aerosol-forming substance to aerosol-forming substance, the amount of liquid aerosol-forming substances can usually vary from about 20 mg to about 140 mg, and preferably from about 40 mg to about 110 mg. As much as possible of the aerosol generator contained on the substrate should be released to the user as WTPM. Preferably, more than about 2% by weight, more preferably more than about 15% by weight, and most preferably more than about 20% by weight of the aerosol generator contained on the substrate is delivered to the user as WTPM.

The aerosol-generating device may also comprise one or more volatile flavoring agents, such as menthol, vanillin, artificial coffee, tobacco extracts, nicotine, caffeine, spirits and other agents that impart flavor to the aerosol. It may also include any other desirable volatile solids or liquids such as those described in Leffingwell et al., supra. Alternatively, these eventual means may be placed in the mouthpiece, or in the preferred tobacco

the charge.

A particularly preferred aerosol-generating device comprises the aforementioned alumina substrate containing spray-dried tobacco extract, levulinic acid or glucose pentaacetate, one or more flavoring agents, and an aerosol former such as glycerin.

A tobacco charge can be used downstream from the fuel element. In such cases, the hot vapors flow through the tobacco to extract and distill the volatile constituents from the tobacco, without combustion or significant pyrolysis. The user thus receives an aerosol containing the flavor and flavorings of natural tobacco, without the many combustion products produced by a normal cigarette.

The heat-conducting material used in preferred embodiments as a container for the aerosol-generating device is typically a metal foil, such as aluminum foil, which varies in thickness from less than about 0.01 mm to about 0.1 mm or more. The thickness and/or type of conductive media can be varied (eg, Grafoil, from Union Carbide) to achieve the desired degree of heat transfer.

As shown in the embodiment illustrated in FIG. 1, the heat-conducting part preferably contacts or overlaps the rear part of the fuel element, and can form the container or capsule enclosing the aerosol-producing substrate according to the present invention. Preferably, the heat-conducting part extends over no more than about half the length of the fuel element. More preferably, the heat-conducting part overlaps or otherwise contacts no more than about the rear 5 mm, preferably 2-4 mm of the fuel element. Preferred retracted portions of this type do not affect the ignition or burning characteristics of the fuel element. Such parts help to extinguish the fuel element when it is used up to the point of contact with the conductive part, by acting as a heat reservoir. These parts also do not protrude from the ignition end of the article, even after the fuel element is exhausted.

The insulating parts used in the preferred smoking articles are preferably formed into an elastic sheath of one or more layers of an insulating material. Advantageously, this sheath is at least approximately 0.5 mm thick, preferably at least approximately 1 mm thick. Preferably, the sheath extends over more than about half, if not the entire length of the fuel element. More preferably, it also extends over substantially the entire outer circumference of the fuel element, and the capsule for the aerosol generating device. As shown in the embodiment in Figure 1, different materials can be used to isolate these two components of the article.

The current preferred insulating materials, especially for the fuel element, are ceramic fibers, such as glass fibers. Preferred glass fibers include experimental materials manufactured by Owens-Corning of Toledo, Ohio under the designations C GLASS S-158, 6432 and 6437. Other suitable insulating materials, preferably non-combustible inorganic materials may also be used.

In order to maximize the aerosol delivery, which can otherwise be diluted by radial (ie from the outside) air infiltration through the article, a non-porous paper can be used from the aerosol generating device to the mouth end.

Paper types such as these are known in the cigarette and/or paper industry, and mixtures of such paper types can be used for different functional effects. Preferred paper types used in the articles of the present invention include RJR Archer's 88-17234 paper, RJR Archer's 8-0560-36 Tipping with Lip Release paper, Ecusta's 646 Plug Wrap and ECUSTA 30637-801-12001 manufactured by Ecusta of Pisgah Forest, NC , and Kimberly-Clark Corporation's paper types P1768-182, P780-63-5, P850-186-2, P1487-184-2 and P850-1487-125. Preferably, the filter is provided with a series of holes located about 23 mm from the mouth end of the smoking article to provide about 22% air dilution.

The aerosol produced by the preferred smoking articles according to the present invention are chemically simple, consisting essentially of air, oxides of carbon, aerosol formers comprising any desired flavoring substances or other desired volatile substances, water and trace amounts of other substances. The WTPM produced by the preferred articles of this invention has no mutagenic activity as measured by the Ames test, i.e. there is no significant dose-response relationship between the WTPM produced by the preferred smoking articles of the present invention and the number of revertants occurring in standard test microorganisms who are exposed to such products. According to the originators of the Ames test, a significant dose-dependent response indicates the presence of mutagenic substances in the products being tested. See Ames et al., Mut. Res.. 31: 347-364 (1975); Nagao et al., Mut. Res.. 42: 335

(1977).

A further advantage of the preferred embodiments of the present invention is the relative lack of ash produced upon use, compared to ash from other cigarettes. As the preferred carbon fuel element is burned, it is essentially converted to oxides of carbon, with relatively little ash generation, and therefore there is no need to dispose of ash when using the smoking article of the present invention.

The use of the improved device for dispensing flavors according to the present invention in cigarettes shall be further illustrated with reference to the following examples which will help to understand the present invention, but which shall not be construed as a limitation thereof. All percentages reported herein, unless otherwise stated, are % by weight. All temperatures are expressed in degrees Celsius and are uncorrected.

Example I

A cigarette of the type illustrated in Figure 1 was made in the following manner.

A. Preparation of fuel source

The fuel element (10 mm long, 4.5 mm outer diameter) with an apparent (bulk) density of approximately 0.86 g/cc was fabricated from carbon (90 wt%), SCMC binder (10 wt%) and K2C03 (1% by weight).

The carbon was produced by carbonizing a non-talc-containing grade of Grand Prairie Canadian Kraft harvewood paper under a nitrogen atmosphere, by gradually increasing the temperature by about 10 °C per hour to a final carbonization temperature of 750°C.

After cooling under nitrogen to less than about 35°C, the carbon was ground to a minus 200 (U.S.) mesh size. The powdered carbon was then heated to a temperature of up to about 850°C to remove volatiles.

After cooling again under nitrogen to less than about 35°C, the carbon was ground to a fine powder, ie a powder having an average particle size of from about 0.1 to 50 microns.

This fine powder was mixed with Hercules 7HF SCMC binder (9 parts carbon : 1 part binder), 1 wt% K 2 CO 3 , and sufficient water to make a stiff dough-like paste.

Fuel elements were extruded from this paste with seven central holes, each about 0.021 inch (0.53 mm) in diameter, and six peripheral holes, each about 0.01 inch (0.25 mm) in diameter. The tissue thickness or distance between the central holes was approximately 0.008 inch (0.20 mm) and the average outer tissue thickness (distance between the periphery and the peripheral holes) was 0.019 inch (0.48 mm) as shown in Figure

IA.

These fuel elements were then baked out under a nitrogen atmosphere at 900°C for three hours after forming.

B. Test-dried extract

A mixture of smoke-cured tobaccos was ground to a medium dust and extracted with water in a stainless steel tank at a concentration of from about 1 to 1.5 pounds of tobacco per gallon of water (0.12-0.18 kg/liter). The extraction was carried out at ambient temperature using mechanical stirring for from about 1 hour to about 3 hours. The mixture was centrifuged to remove suspended solids, and the aqueous extract was spray-dried by continuously pumping the aqueous solution into a conventional spray dryer, an Anhydro Size No. 1, at an inlet temperature of from approximately 215°C to 230°C, and collect the dried powder material at the outlet of the dryer. The outlet temperature varied from approximately 82-90°C.

C. Preparation of sintered alumina

Alumina with a high specific surface area (specific surface area of about 280 m<2>/g) from W.R. Grace & Co., with a mesh size of from -14 to +20 (U.S.) was sintered at an immersion temperature of about 1400°C to 1550°C for about one hour, washed with water and dried. This sintered alumina was combined, in a two-step process, with the ingredients shown in Table I in the portions shown:

In the first step, the spray-dried tobacco extract was mixed with sufficient water to make a slurry. This slurry was then applied to the alumina carrier described above by mixing until the slurry was uniformly absorbed by the alumina. The treated alumina was then dried to reduce the moisture content to approximately 1% by weight. In the second step, this treated alumina was mixed with a combination of the other listed ingredients until the liquid was substantially absorbed into the alumina carrier.

D. Composition

The capsule used to construct the cigarette in

Figure 1 was produced from deep-drawn aluminium. The capsule had an average wall thickness of about 0.004 inches (0.1 mm), and was about 30 mm long, with an outer diameter of about 4.5 mm. The rear end of the container was sealed except for two slit-like openings (each about 0.65 x 3.45 mm, spaced about 1.14 mm apart) to allow passage of the aerosol generator to the user. About 330 mg of the aerosol producing substrate described above was used to fill the capsule. A fuel element prepared as above was inserted into the open end of the filled capsule to a depth of approximately 3 mm.

E. Insulating jacket

The fuel element-capsule combination was wrapped at the fuel element end with a 10 mm long fiberglass jacket of Owens-Corning C GLASS S-158 with 3 wt% pectin binder, to a diameter of about 7.5 mm. The fiberglass jacket was then wrapped with an inner wrapping material, a Kimberly-Clark experimental paper designated P780-63-5.

F. Tobacco roll

A 7.5 mm diameter tobacco stick (28 mm long) with a wrap of Kimberly-Clark's P1487-125 paper was modified by inserting a probe to make a longitudinal passage of approximately 4.5 mm diameter therein.

G. Assembly

The sheathed fuel element - capsule combination was fed into the passage in the tobacco rod until the fiberglass sheath butted against the tobacco. The fiberglass and tobacco sections were joined with an outer wrap material that enclosed both the fuel element/insulating jacket/inner wrap combination and the wrapped tobacco rod. The outer wrapper was a Kimberly-Clark paper designated P1768-182.

A nozzle of the type illustrated in Figure 1 was constructed by assembling two sections; (1) a 10 mm long, 7.5 mm diameter carbon filled tobacco sheet material close to the capsule, wrapped with Kimberly Clark's P850-184-2 paper and (2) a 30 mm long, 7.5 diameter cylindrical segment of a non-woven meltblown thermoplastic polypropylene fabric supplied by Kimberly-Clark Corporation, designated PP-100-F, wrapped with Kimberly-Clark Corporation's P1487-184-2 paper.

The carbon-filled tobacco sheet material was prepared by adding about 17% of PCB-G activated carbon from Calgon Carbon Corporation to a pulp used to make a sheet material supplied from Kimberly-Clark Corporation, designated P144-185-GAPF. This material was added with about 4.5% by weight of menthol flavoring by an internal leaf transfer method. Both sections of the mouthpiece were made by passing the tobacco paper and the web of thermoplastic fibers through the double cone forming system described above. These two sections were assembled with a binding wrap of Kimberly-Clark Corporation's P850-186-2 paper.

The combined nozzle section was assembled with the jacketed fuel element - capsule section with a final wrap of Ecusta's 30637-801-12001 tipping paper.

Cigarettes produced in this way produced a mentholated aerosol without any undesirable off-flavor due to burning or thermal decomposition of the menthol or other aerosol-forming material. Sensory evaluation comparing such articles to commercially available low tar mentholated cigarettes showed similar results for menthol flavor perception and release.

Example II

Cigarettes similar to those described in Example 1 were constructed to study the migration of menthol from its original location to the fuel source over a 10 day period under 75/40 humidity conditions (75°F, 24°C and 45% relative humidity). All prototypes were added with approximately the same amount of menthol. Prototypes A and B had menthol added directly to both the tobacco sheath and the aerosol-carrying substrate. Prototypes C and D had menthol in the segment of Kimberly-Clark's P144-185-GAPF tobacco paper sheet (the sheet material produced without any any carbon content) placed between the aerosol generating device and the filter. Prototype E had the menthol added to plastic-like beads supplied by Narrden Flavor House, Germany, under the designation NFM. The beads were placed in a cavity made in the filter portion of the article. Prototype F had the menthol added to an experimental sponge material supplied by Advanced Polymer Systems under the designation CH-43-16 and incorporated into P144-185-GAPF tobacco the sheet of paper

(the sheet material produced without any carbon content)

placed between the aerosol generating device and the filter

part of the article. Prototype G, manufactured according to the present invention, had menthol added to a 10 mm segment of the carbon-filled tobacco sheet material according to the present invention placed between the aerosol generating device and the filter.

As can be seen from Figure 2, there is a significant reduction in the migration of menthol to the fuel source in such articles, when the menthol is added to the carbon-filled sheet material of the present invention and used instead of the normal tobacco paper plug.

Claims (6)

1. Smoking article comprising a fuel element (10), a physically separate aerosol-forming device (12) containing a substrate material (14) containing at least one aerosol-forming material, and a nozzle (22) for delivering the aerosol that the aerosol-forming device (12) provides to the smoker, and which preferably contains a filter plug (26) at the mouth end thereof, characterized in that the nozzle (22) contains a carbon-filled sheet material (24) which contains at least one flavouring. 2. Smoking article according to claim 1, characterized in that the carbon-filled sheet material is located in the nozzle (22) between the filter plug (26) and the substrate (14) which contains the aerosol-forming material. 3. Smoking article according to claim 2, characterized in that the carbon-filled sheet material (24) has the shape of a cylinder. 4. Smoking article according to each of claims 1 - 3, characterized in that the flavoring substance is menthol present in an amount of less than approx. 6% by weight. 5. Smoking article according to each of claims 1-4, characterized in that the carbon content in the sheet material (24) is between approx. 5 and approx. 75% by weight. 6. Smoking article according to each of claims 1-5, characterized in that the carbon-filled sheet material (24) comprises carbon-filled tobacco-containing paper, preferably with a tobacco content of approx. 65% by weight.