HK1179481B - Cellulosic material such as tobacco comprising one or more smoke diluents - Google Patents

Description

Cellulosic material, such as tobacco, comprising one or more smoke diluents

The present invention relates to cellulosic material (e.g. tobacco) comprising one or more smoke diluents (smoothers), a process for preparing such cellulosic material, and uses thereof.

Combustible tobacco products or smoking articles (e.g., cigarettes) can produce smoke during use due to incomplete combustion of tobacco and/or other filler materials. The term "mainstream smoke" refers to the mixture of gas and particulate matter (aerosol) passing beneath the rod of smokable material and exiting through the filter end. This mainstream smoke comprises smoke that is drawn through an ignition zone (lightedregion) of the smoking article and which typically comprises components such as "tar", nicotine and carbon monoxide (CO). Such components are known in the art as "smoke deliveries (smolderoutputs)".

A number of strategies have been used in an attempt to reduce smoke delivery, such as improving selective filtration of cigarette smoke.

It is also known, for example, to include filler materials, particularly non-combustible filler materials, in combustible smoking materials for smoking articles such as cigarettes. Such filler materials include inorganic materials such as dolomite, diatomaceous earth, calcium carbonate, magnesium oxide and aluminum oxide; and organic materials such as starch, cellulose, pectin, and alginate or other materials known to those skilled in the art to be capable of acting as binders for filler materials.

However, one disadvantage of such filler materials is that they can alter the taste and flavour of the smoke of the smoking article, which is unacceptable to smokers.

It is known to include diluents in smoking articles, such as cigarettes. Diluents are compounds that evaporate during smoking and are transferred into the mainstream smoke in aerosol form. They are generally selected so that they can be transferred into the flue gas substantially intact. The other components of the smoke (in the case of tobacco-containing smoking articles, components derived from tobacco) are thus "diluted" by this means.

Such flue gas diluents may be included in solid form (e.g., powder) which is simply mixed with the cellulosic material or filler material. However, such powders are susceptible to loss during subsequent processing to produce smoking articles.

Alternatively, the smoke diluent may be added in the form of a liquid or gel, sprayed onto or mixed with the cellulose or filler material, or wherein the cellulose or filler material is otherwise coated so that a quantity of diluent remains on the material after drying. The smoke diluent may be mixed with a volatile liquid, such as a suitable solvent, and sprayed onto the filler material or tobacco material. The solvent is expected to evaporate, leaving the smoke diluent on the surface of the tobacco or filler material.

However, these methods may result in only the surface of the target material being covered with the diluent. The resulting smoke diluent present on the surface of the cellulosic material or filler material can have adverse effects during subsequent processing to produce a smoking article. Another problem associated with including a diluent in this way is that it can affect the surface properties of the cellulosic material, for example, such that it becomes sticky, which has a serious adverse effect on the processing of the material, in particular it will have a tendency to cake and will not flow.

It is desirable to maximize the amount of smoke diluent that can be included in the combustible smoking material for inclusion in the smoking article. It is also desirable to add the flue gas diluent in such a way that it does not present the problems associated with the processing of the combustible adsorbent material.

The term "processing" refers to any method known to those skilled in the art for making combustible tobacco products. For example, mixing and cutting the cellulosic material and making a smoking article.

It would be desirable to provide a cellulosic material containing a greater amount of smoke diluent than known comparable cellulosic materials without unduly adversely affecting the properties of the material and other properties of the product in which it is used. For example, the constituent materials of the smokable material of the smoking article are desirably free-flowing, having minimal viscosity. This allows easy handling and processing of the material. Furthermore, it is desirable that the addition of the smoke diluent, and the presence of the smoke diluent in or on the cellulosic material, does not significantly or adversely affect the flavour and taste of the smoking article.

An advantage of the present invention is that it can provide a smokable material comprising cellulosic material mixed with a smoke diluent, which also retains the desirable characteristics of the smokable material.

Another advantage of the present invention is that it can provide a method for providing cellulosic material mixed with flue gas diluent at levels that promote flexibility in optimizing the flue gas dilution potential.

According to a first aspect of the present invention there is provided cellulosic material to which has been added a flue gas diluent, at least some of which is held in a porous structure (cellular structure) of the cellulosic material, the flue gas diluent being held in and optionally on the cellulosic material in an amount of greater than or equal to 5% based on the dry weight of the cellulosic material.

According to a second aspect, there is provided a process for preparing a cellulosic material according to the first aspect of the invention.

According to a third aspect of the present invention there is provided a smoking article comprising a cellulosic material according to the first aspect of the present invention, and/or a cellulosic material prepared according to the method of the second aspect of the present invention.

According to a fourth aspect of the present invention there is provided a method of producing a smoking article comprising mixing a cellulosic material according to the first aspect with one or more other cellulosic materials and/or other smoking article ingredients.

According to a fifth aspect of the present invention there is provided the use of a cellulosic material according to the first aspect of the present invention in the manufacture of a smoking article.

Those skilled in the art will appreciate that a balance must be struck between including a smoke diluent in the cellulosic material in an amount sufficient to effect the desired reduction in smoke deliveries, and providing a cellulosic material that can be used without problems in typical manufacturing settings for smoking articles (i.e., the cellulosic material is sufficiently free-flowing so that it does not stick to or otherwise inhibit cigarette manufacturing machinery). Such a balance is more easily achieved by the present invention because it allows more diluent to be included in the treated cellulosic material without the surface of the cellulosic material being affected to the extent that it causes unwanted stickiness and clumping.

As used herein, the phrase "cellulosic material" means any material comprising cellulose. The material may be a tobacco material, such as stems, leaves, pollen, reconstituted tobacco, or a mixture thereof. Suitable tobacco materials include the following types: virginia (Virginia) or flue-cured, Burley, oriental or mixed tobacco material. The tobacco may be expanded, such as Dry Ice Expanded Tobacco (DIET), or processed by any other means, such as extrusion. The stalk tobacco may be pre-processed or unprocessed, and may be, for example, Solid Stalk (SS); minced dried stems (SDS); steam Treated Stems (STS); or any combination thereof. Tobacco having an open pore structure is preferably used as the diluent carrier.

As used herein, the phrase "within the porous structure" means that the flue gas diluent is located in or within the walls of the cellulose material pores (cells), or between adjacent cellulose material pores. The term "retained" means that at least some of the smoke diluent remains within the porous structure of the cellulosic material and adheres to the surface of the cellulosic material throughout typical processing conditions experienced by the cellulosic material (which is intended to be included in a smoking article), such as mixing and incorporation into a rod of smokable material. Without being bound by theory, the presence of the smoke diluent in the porous structure of the cellulosic material promotes "free flow" and reduces the caking tendency in the impregnated material.

In certain embodiments, the weight of said smoke diluent retained within the porous structure of the cellulosic material and optionally on the surface of the cellulosic material is greater than or equal to 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45% or 50% based on the dry weight of the cellulosic material.

In certain embodiments, the cellulosic material is SDS.

In an alternative embodiment, the cellulosic material is leaf silk or DIET. DIET undergoes processing that causes the porous structure of the tobacco to expand. This has the advantage that it can allow more diluent to be retained within its porous structure and/or it can facilitate penetration of the diluent into the porous structure.

Preferably, the cellulosic material has a moisture content suitable for use in conventional smoking article processing equipment. In addition, the cellulosic material preferably has a consistency suitable for use in typical smoking article manufacturing equipment. For example, the cellulosic material is preferably free-flowing and does not stick to cigarette making machinery, impeding manufacturing.

Suitable moisture content of cellulosic material for use with such devices is less than about 20%. Thus, it is preferred that the cellulosic material of the present invention comprise no greater than 20% moisture, and more preferably the cellulosic material has a moisture content of no greater than about 18%, no greater than about 15%, or no greater than about 12%.

As used herein, the terms "smoke diluent" and "diluent" refer to a material for incorporation into a smoking article for the purpose of reducing smoke deliveries as the combustible smoking material is combusted and the smoking article is consumed. The smoke diluent is adapted for incorporation into the combustible smoking material of a smoking article.

The diluent is at least one aerosol former which may be, for example, a polyol aerosol generator, or a non-polyol aerosol generator, preferably a non-polyol aerosol generator. It may be solid or liquid at room temperature, but is preferably liquid at room temperature, suitable polyols include sorbitol, glycerol and glycols such as propylene glycol or triethylene glycol. Suitable non-polyols include monohydric alcohols, high boiling hydrocarbons, acids (such as lactic acid) and esters (such as diacetin, triacetin, triethyl citrate or isopropyl myristate).

Preferably, the flue gas diluent has a melting point of less than about 110, 105, 100, 95, 90, or 85 ℃.

In the present invention, the smoke diluent is preferably glycerol, triacetin, triethyl citrate or isopropyl myristate.

Combinations of diluents of equal or unequal proportions may be used.

It is known to include some of these materials in combustible tobacco products for other purposes than as smoke diluents. For example, triacetin and diacetin have previously been used in smoking articles as non-polyol aerosol generators (WO 98/57556). TEGDA, triacetin and glycerol are known plasticizers. Glycerol is commonly used as a humectant in tobacco because it improves the moisture absorption and mechanical properties of tobacco. In US6571801, tobacco is loaded with 4-15% humectants such as glycerol, propylene glycol, sorbitol or diethylene glycol. Glycerol has been used as an aerosol generating material in smoking articles in amounts of 5 to 20% by weight of the sheet material (see, e.g., WO 03/092416). Glycerol has also been used to improve smoke filtration (US 3674540; US 5860428; US 6397852).

The flue gas diluent may be present in the cellulosic material of the invention in a form that is solid or liquid at room temperature.

In some embodiments, the smoke diluent is a substantially water-soluble material. In an alternative embodiment, the smoke diluent is a water-insoluble or slightly water-soluble material. In other embodiments, the diluent is capable of being dissolved in a non-aqueous solvent.

Conventional methods for adding diluents to cellulosic materials can result in the diluents being coated on the surface of the cellulosic material. In contrast, the present invention provides a process which results in at least some penetration of the smoke diluent into the porous structure of the cellulosic material.

In a preferred embodiment, the positioning of the flue gas diluent within the porous structure of the cellulosic material and optionally on the surface of the cellulosic material is achieved by an impregnation process, which preferably promotes penetration of the diluent into the porous structure.

The methods of the present invention comprise the use of certain conditions before, during or after the application of the flue gas diluent to the cellulosic material, and/or the use of one or more carriers with which the diluent is applied to the cellulosic material.

In some embodiments, the method comprises subjecting the cellulosic material to one or more treatment steps prior to or during application of the smoke diluent. These treatment steps are intended to increase the permeability of the diluent into the cellulosic material when the diluent is applied. For example, the cellulosic material may be subjected to one or more treatments capable of drying and/or driving off air present in the material. The cellulosic material may be treated to rupture at least some of the pores, thereby providing a means by which the diluent can enter the pore interior when applied, which would otherwise be sealed.

The treatment steps (which dry and/or remove air from the cellulosic material) include heat treatment, vacuum treatment, liquid impregnation, vapor treatment, pressurized liquid impregnation, vacuum freeze drying, and the use of supercritical fluids.

The heat treatment involves heating the cellulosic material to very dry (bonedryness). This process step also causes the pore air to be expelled by expansion.

Vacuum treatment involves applying a vacuum to drive air from the cellulosic material.

Liquid impregnation involves applying a hot liquid to the cold cellulosic material or applying a cold liquid to the hot cellulosic material to soften the pore walls and facilitate pore air removal by means of liquid infusion. The temperature difference between the liquid and the material may be at least 30, 40, 50, 60, 70, 80, 90 or 100 ℃ or higher.

Pressurized liquid impregnation involves applying hot liquid under pressure to cold cellulosic material, or applying cold liquid to hot cellulosic material. This treatment may also include a vacuum pre-treatment stage prior to pressure impregnation, followed by vacuum drying of the impregnated material until the desired moisture content is reached. The pore air is removed by forced liquid infusion.

Steam treatment involves applying steam to soften the walls of the pores of the cellulosic material and removing the pore air by means of steam infusion.

Vacuum freeze-drying can be used to dry the cellulosic material to extreme dryness, and to remove air from the pores.

Air may also be treated by the use of supercritical fluids (e.g., CO)₂) Infused and then expanded to be removed from the pores of the cellulosic material.

In a preferred embodiment, the method of the invention comprises the use of at least two treatment steps.

In a preferred embodiment, the method comprises subjecting the cellulosic material to a treatment step having the combined function of drying the cellulosic material and partially driving off pore air.

It has been shown that said treatment of the cellulosic material promotes the penetration of the smoke diluent into the porous structure of the cellulosic material as a result of the combined function of drying the cellulosic material and partially driving off the pore air resulting from the drying process. The smoke diluent is applied as a solution or suspension, resulting in the smoke diluent entering the dry cellulose pores as a result of the capillary wetting process of the pore walls.

In some embodiments of the invention, it is preferred that the cellulosic material is subjected to a treatment step involving heating. It has been shown that as the air within the pores shrinks during cooling after the heat treatment, the flue gas diluent is drawn further into the heat treated pores.

The method of the invention can also be used for cellulosic starting materials, which are pretreated cellulosic materials, such as leaf silks, mixed silks (cutbgind), SDS, STS or DIET. When such a cellulosic material is used, the process preferably includes a treatment step involving heating the pretreated cellulosic material to enhance penetration or impregnation of the flue gas diluent into the porous structure of the cellulosic material.

In embodiments of the invention involving heat treatment, the cellulosic material is preferably treated for at least about 5 minutes, preferably at least about 10 minutes, preferably at least about 20 minutes, preferably at least about 30 minutes, and most preferably from about 30 to 45 minutes.

In embodiments of the invention involving heat treatment, the heat treatment step may be performed under pressure, and the material may also be subjected to steam and/or vacuum. Heat, steam, vacuum and/or pressure may be applied separately or sequentially. The most suitable combination of methods will depend on the particular starting materials used and may involve an empirical iterative scheme.

If the heat treatment is not pressurized, the temperature used may be at least about 90 deg.C, preferably about 100 deg.C, more preferably about 105 deg.C and 110 deg.C.

The method of the present invention further comprises the step of applying a flue gas diluent to the cellulosic material. In some cases, the liquid smoke diluent may be applied directly to the cellulosic material.

In some embodiments, the smoke diluent is applied in the form of a solution, emulsion, or suspension. To prepare them, the flue gas diluent is mixed with one or more carriers. Suitable carriers include water; organic solvents such as alcohols, hydrocarbons or other suitable organic based solvents; liquids or gases, such as carbon dioxide (which may be supercritical); or other suitable agent or carrier capable of forming a solution, emulsion or suspension of the smoke diluent. Suitable carriers include water; alcohols such as methanol and ethanol; liquid or gaseous carbon dioxide. The choice of carrier is preferably compatible with tobacco processing techniques. The use of an aqueous carrier is particularly preferred because it avoids the use of large amounts of flammable solvents.

The carrier may be a solvent in which the one or more flue gas diluents are capable of being dissolved. Where more than one flue gas diluent is used, the carrier may be a solvent for one or more of the diluents.

In some embodiments, the support is permeable to the pore walls of the cellulosic material.

The carrier may be an agent having drying properties, wherein the carrier is volatile below or around those temperatures employed, for example, when the smoke diluent is applied to the cellulosic material.

It has been shown that one way in which the use of a carrier can facilitate penetration of the flue gas diluent into the porous structure of the cellulosic material is by helping to remove residual moisture from the walls of the pores of the cellulosic material and/or forcing the flue gas diluent into the pores.

When the carrier is a liquid, the smoke diluent may be in solution, suspension or provided as an emulsion with the carrier. In a preferred embodiment, the smoke diluent is in the form of a solution or emulsion. In some embodiments, the smoke diluent may be in the form of an aqueous solution or emulsion.

In some embodiments, the flue gas diluent is in the form of a solution rather than a suspension. This is preferred because application of the suspension results in greater surface deposition of the smoke diluent on the cellulosic material rather than into the porous structure.

A high shear mixer may be used to prepare the flue gas diluent and/or any carrier for application to the cellulosic material. Such processing typically produces very small droplets of diluent and/or carrier.

It has been shown that processing in this manner can increase the efficiency of penetration of the diluent into the porous structure of the cellulosic material as a result of the small droplet size of the diluent. This is particularly true where the flue gas diluent is a sparingly water-soluble or insoluble liquid which is mixed with water to form an aqueous emulsion.

The emulsion of the smoke diluent of the present invention should remain stable, wherein the diluent should not undergo chemical changes during emulsion preparation and application to the cellulosic material. In some embodiments, this may be achieved as follows: by continuous high shear mixing of the emulsion, and/or addition of selected emulsifiers, prior to or during the application process.

The solubility of the emulsions of the invention can be increased by known means, such as conventional heated emulsion techniques.

The composition of the flue gas diluent mixed in or provided with one or more carriers can be calculated such that the cellulosic material (which is formed by adding the emulsion to the cellulosic material) comprises a desired diluent content (based on the starting dry weight of the cellulosic material) and moisture content.

The application of the flue gas diluent to the cellulosic material may be carried out as follows: soaking and/or mixing the cellulosic material into excess flue gas diluent followed by filtering the excess diluent; saturating the cellulosic material with a desired amount of flue gas diluent; spraying the cellulosic material with a flue gas diluent and/or pressure spraying the cellulosic material with a flue gas diluent. It is also possible to employ refluxing of the material in the carrier with a diluent followed by removal of the carrier by evaporation methods, such as vacuum evaporation techniques.

In embodiments according to the second aspect of the invention involving heating the cellulosic material, the flue gas diluent is preferably contacted with the cellulosic material while the cellulosic material is hot.

The application of the flue gas diluent to the cellulosic material can be carried out at an elevated temperature. For example at a temperature greater than about 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 105 ℃ or 110 ℃.

In embodiments where the cellulosic material is mixed with a smoke diluent, the mixing is preferably gentle to prevent reduction of the cellulosic material particle size. For example, a planetary mixer may be used.

In embodiments where the cellulosic material is sprayed with the flue gas diluent, the method can include optimally uniformly spraying the diluent onto the cellulosic material veil. The application rate can be consistent to provide a consistent target diluent loading and to provide a consistent moisture content for the cellulosic material. In addition, it may be advantageous to have one or more of the following: optimal surface area of the cellulosic material (e.g., provided by nearly discrete tumbling of small pieces of cellulosic material); a consistent flow of cellulosic material; and a cooling phase after the spraying phase and/or a build-up (filling) time after the spraying phase. Conventional spray and/or pumping techniques may be used to achieve the spray described herein.

In some embodiments, the cellulosic material is immersed or mixed (preferably while hot) into an excess of flue gas diluent (preferably in the form of an aqueous solution or emulsion).

In a preferred embodiment, the diluent delivery system according to the second aspect of the invention comprises subjecting the cellulosic material to a treatment, such as heat treatment, vacuum treatment, liquid impregnation, steam treatment or vacuum freeze-drying, before and/or during the treatment of the cellulosic material with the flue gas diluent. Preferably, the diluent delivery system involves heat treating the cellulosic material followed by soaking and/or spraying the cellulosic material with the flue gas diluent.

The cellulosic material is then dried to a suitable moisture content and may optionally be sieved.

The cellulosic material of the present invention can then be used to prepare a smoking article.

According to the present invention, there is provided a smoking article comprising a cellulosic material according to the first aspect of the invention, and/or a cellulosic material prepared by a method according to the second aspect of the invention.

In a preferred embodiment, the cellulosic material comprising the smoke diluent undergoes minimal processing prior to incorporation into the smoking article.

By the term "processing" is meant any aspect of the methods known to those skilled in the art for making combustible tobacco products, such as mixing and cutting the cellulosic material and making smoking articles.

Preferably the smoking article comprises a cigarette.

In preferred embodiments, the smoking article comprises a smokable filler material comprising at least 5%, at least 10%, at least 20%, at least 30% or at least 35%, at least 40% or at least 45% or at least 50% by weight of smoke diluent.

According to the present invention, there is provided a method of producing a smoking article comprising mixing the cellulosic material of the invention with one or more other cellulosic materials and/or other smoking article ingredients.

In a further aspect, there is provided the use of the cellulosic material of the invention in the manufacture of a smoking article.

The invention will now be described by way of example, with reference to the following drawings:

FIG. 1 shows a schematic diagram of an embodiment of a method of continuous spray coating flow through an inclined tumble dryer;

FIG. 2 shows a schematic diagram of the application of heat, steam, vacuum and/or pressure in a suitable combination or sequence while agitating cellulosic material in a batch mixing process;

fig. 3A is a Cryo scanning electron microscope (Cryo-SEM) image showing the porous structure of the cellulose material.

Fig. 3B is a Cryo-SEM image showing the porous structure of a cellulosic material after impregnation with a diluent according to the present invention.

In this regard, fig. 1, which illustrates a continuous spray flow through process, shows a holding vessel 1 which may be used to hold a flue gas diluent or an aqueous solution or emulsion thereof. The holding vessel may be in fluid communication with a high shear mixer 2, such as a Silverson in-line mixer, via connecting line 3, to enable the aqueous solution and/or emulsion to be held by recirculating the contents of the holding vessel through the high shear mixer 2.

The dried cellulosic material (e.g., SDS having a water content of 6-7%) is heated while passing through the dryer 4 (e.g., flowing through an inclined rotating cylindrical drum dryer) such that the air within the pores expands. The dryer 4 may be in fluid communication with the holding vessel via a spray system which may include a connecting line 5, a pump 6, a safety relief valve 7, a pinch valve 8, a spray device 9, and a pressure gauge 10, preferably proximate to the outlet of the dryer (e.g., a nozzle or spray head).

As the tumble dryer 4 rotates, an aqueous solution or emulsion of flue gas diluent is sprayed at a suitable, preferably uniform rate onto the falling curtain of hot fibrous material via the spraying device 9 immediately before the cellulosic material leaves the dryer 4 and falls onto the conveyor 11.

The conveyed cellulosic material can be accumulated for a period of time (e.g., about at least 12 hours) during which the cellulosic material is cooled. The cooled cellulosic material may optionally be dried to a moisture content acceptable for blending and cigarette manufacture.

As used herein, the term "stacking" is a conventional term in the art of smoking article manufacture and refers to the step of increasing the moisture content of cellulosic material.

Figure 2 illustrates a batch mixing process by which the emulsion is emulsified or mixed by acting on a high shear mixer.

A holding vessel containing a flue gas diluent or an aqueous solution or emulsion thereof, and fluid delivery to the spray system is similar to that shown in figure 1. Specifically, components 1, 2, 3, 5, 6, 7, 8 and 10 are the same as shown in FIG. 1.

In addition, the apparatus is in fluid communication with the mixing vessel 12 through the spray system 14. The container 12 may be heated, for example, by a steam heating jacket 13. The cellulosic material in the vessel 12 is agitated, for example, by an agitating device 15 and wall scraping action (wall-scraping) 16, and these agitating devices can be operated independently.

An aqueous solution or emulsion of the flue gas diluent is sprayed onto the cellulosic material agitated via the agitation device. Mixing vessel 12 may contain a device 17 through which steam may be injected into the vessel, through which the vessel may be pressurized 18 or depressurized 19. The mixing vessel may be equipped with a pressure gauge 20 and a safety relief valve 21.

Examples

Example 1 impregnation of Diluent Using planetary Mixer

Shredded dry stem tobacco (SDS) was impregnated with different diluents according to the following method, and the level of impregnation was evaluated.

SDS was dried in an oven at 105 ℃ and 110 ℃ for about 30-45 minutes until the tobacco was "extremely dry".

An aqueous solution (or emulsion) of the smoke diluent was prepared using a Silverson high shear mixer and added to the hot SDS. The SDS and flue gas diluent solution (or emulsion) were then mixed using a planetary mixer and cooled.

The mixture was then dried in foil-lined trays at 22 ℃ and 60% relative humidity for about 12 h. In some cases, the mixture is further dried in air at room temperature, where desired.

In some cases, where desired, the cellulosic material is lightly sieved using a coarse sieve.

The resulting material was found to be free flowing and non-tacky.

Table 1 shows different smoke diluent impregnation levels of SDS. The target impregnation levels are shown and the actual diluent impregnation levels are given in parentheses for comparison.

It was found that dry SDS absorbed up to 70 wt% of the liquid without excessive drainage (draining) or "mashing".

TABLE 1

A mixture of the impregnated SDS material and the leaf discs was then prepared in which the SDS and the leaf discs were present in equal amounts.

Different mixtures were found to have a wide range of diluent content and they are summarized in table 2.

The entire blend was found to be free flowing and non-tacky and suitable for use in conventional cigarette making machines.

TABLE 2

Diluent	The diluent in the mixture%
		Triacetin	12-23
Citric acid triethyl ester	5-21
		Myristic acid isopropyl ester	4-23

Example 2-impregnation of Diluent Using continuous spray, flow through inclined tumble dryer Process

Shredded dried stem tobacco (SDS) was impregnated with triacetin according to the following method, which is shown in figure 1, and the diluent content in cigarettes containing the impregnated tobacco was evaluated.

SDS was dried to about 6% moisture using a flow-through inclined rotary drum dryer following the conventional procedure used in tobacco drying.

In the second treatment, the triacetin/water emulsion was sprayed onto a hot falling pre-dried SDS curtain using a flow-through inclined drum dryer modified to include a continuous spray system near the material exit point.

The outgoing material is then collected and stacked with the desired diluent impregnation level and moisture content (typically 18%).

The material is dried via additional drum drying to the desired final moisture content (typically 13%). The resulting material is free-flowing and non-tacky and can be satisfactorily blended with other tobacco in desired proportions via conventional tobacco processing methods.

Cigarettes made with a mixture of 50% lamina and 50% impregnated SDS (table 3-TEST cigarettes).

The SDS dip content measured was 20% triacetin. The triacetin content measured in the final mixture was 7% (the reduction in diluent content can be attributed to processing losses).

The smoke chemistry (TPM, Total particulate matter; NFDPM, Dry particulate matter without nicotine) of the cigarettes is shown in Table 3. The cigarettes are manufactured using conventional cigarette manufacturing methods and machinery. The control cigarette was made using the lamina blend. All cigarettes were manufactured using the same paper and filter specifications.

TABLE 3

Sample cigarette	TPM (mg/cigarette)	Water (mg/cigarette)	Nicotine (mg/cigarette)	NFDPM (mg/cigarette)	No of smoke spray	CO (mg/cigarette)	Triacetin (mg/cigarette)	Dilution ratio of flue gas%
									Control	8.6	0.48	0.76	7.4	8.2	6.5	0.16	2.2
TEST	7.6	0.32	0.29	7.0	6.2	5.1	2.90	41.4

The flue gas dilution ratio is calculated as follows:

[ triacetin (mg/cigarette)/NFDPM (mg/cigarette) in Smoke ] x100

Cigarette filters typically have triacetin added as a "plasticizer" to improve the firmness of the filter. The dilution observed in the control cigarette is believed to be due to the transfer of filter triacetin to the smoke.

The data shown in table 3 clearly demonstrate that the triacetin-impregnated SDS incorporated into the tobacco mixture acts as an effective smoke-diluting material, transferring large amounts of triacetin into the smoke.

Example 3: impregnating diluents using a batch mixing process

Shredded dry stem tobacco (SDS) was impregnated with triacetin according to the following method, which is shown in fig. 2, and after impregnation with diluent, cryo-scanning electron microscopy images of the material were obtained. The diluent content of cigarettes containing the impregnated tobacco was also evaluated.

2kg of SDS was placed in a mixing vessel equipped with a scraped wall mixing baffle, stirrer, heating mantle, steam injection, pressure and vacuum capability. The mixing baffle is activated and continued to run continuously throughout the process. The SDS moisture was raised to about 35% by steam injection, while the temperature of the mixer housing was raised to 70 ℃.

860g of triacetin were emulsified in 400g of water in a separate vessel for at least 90 s.

The triacetin emulsion was then added to the mixer over a period of 70 seconds. The SDS was then mixed for 3 minutes and dried to the appropriate humidity by raising the temperature of the mixing vessel jacket to 94 ℃ and running the vacuum pump at 450mbar for 37 minutes.

The target triacetin impregnation content was 30%, and the measured content was 33%.

The resulting material was found to be free flowing and non-tacky.

Figures 3A and 3B show Cryo-scanning electron micrographs of tobacco material before and after triacetin incorporation. Figure 3A shows the unprocessed control SDS and it can be seen that the porous structure is material free, in contrast figure 3B clearly shows the presence of triacetin in the porous structure.

The smoke dilution capacity of SDS material impregnated with triacetin according to the method described was evaluated.

Cigarettes were manufactured using a mixture of 50% lamina and 50% impregnated SDS. The target impregnation content of triacetin for SDS was 20%, and the measured impregnation content was 21%. The measured triacetin content in the final mixture was 8% (the reduction in diluent level can be attributed to processing losses).

The smoke chemistry of the cigarettes is illustrated in table 4. The cigarettes are manufactured using conventional cigarette manufacturing methods and machinery. Refence cigarettes were made using a leaf blend, SDSBLENDCONTROL cigarettes containing 50% leaves and 50% non-impregnated SDS, and TEST cigarettes were made using a blend of the 50% leaves and 50% impregnated SDS described above. All cigarettes were manufactured using the same paper and filter specifications.

TABLE 4

(rounded to 1 decimal place).

The data shown in table 4 clearly demonstrate that the triacetin-impregnated SDS incorporated into the tobacco mixture acts as an effective smoke-diluting material, transferring large amounts of triacetin into the smoke.

Claims (24)

1. A cellulosic material having one or more smoke diluents within its porous structure and optionally on its surface, wherein the weight of said smoke diluents is greater than or equal to 5% based on the dry weight of the cellulosic material.

2. The cellulosic material of claim 1, wherein the cellulosic material has a moisture content suitable for use in a smoking article processing device.

3. The cellulosic material of claim 1 or 2, wherein the cellulosic material is a tobacco material.

4. The cellulosic material of claim 3, wherein the diluent is retained in the porous structure of the tobacco material when used in a tobacco product.

5. The cellulosic material of claim 3, wherein the diluent is retained in the porous structure of the tobacco material and on the surface of the tobacco material when used in a tobacco product.

6. The cellulosic material of claim 3, wherein the tobacco material is selected from the group consisting of: solid stems, chopped dry stems, steam treated stems, cut lamina, stems, DIET, reconstituted tobacco, mixed cut, and mixtures thereof.

7. The cellulosic material of claim 6, wherein the tobacco material is shredded stems.

8. The cellulosic material of claim 1, wherein the flue gas diluent has a melting point of less than about 95 ℃.

9. A cellulosic material according to claim 1, wherein the smoke diluent is a water-insoluble or slightly water-soluble liquid.

10. A cellulosic material according to claim 9, wherein the flue gas diluent is any one or more compounds selected from the group consisting of: glycerol, triacetin, triethyl citrate, and isopropyl myristate.

11. A process for preparing a cellulosic material having a smoke diluent located in its porous structure and optionally on its surface.

12. The method of claim 11, comprising using a diluent delivery system.

13. The method of claim 12, wherein the diluent delivery system comprises subjecting the cellulosic material to one or more treatments selected from the group consisting of: heat treatment, vacuum treatment, liquid immersion treatment, vapor treatment or vacuum freeze-drying.

14. The method according to claim 12 or 13, wherein the diluent delivery system comprises treating the cellulosic material to substantially reduce its water content.

15. The method of claim 11 wherein the flue gas diluent is included in or associated with a carrier.

16. The method of claim 15, wherein the carrier is water, an alcohol, or liquid or gaseous carbon dioxide.

17. The method of claim 15 or 16, wherein the flue gas diluent is in the form of an aqueous solution or emulsion prior to being retained by the cellulosic material.

18. The method of claim 17, wherein the aqueous solution or emulsion is prepared by a process comprising high shear mixing.

19. The method of claim 11 wherein the smoke diluent is added to the porous structure using a continuous spray process.

20. The method of claim 11 wherein the flue gas diluent is added to the porous structure using a batch mixing process.

21. A smoking article comprising the cellulosic material according to any one of claims 1-10.

22. A smoking article according to claim 21, wherein the article is a cigarette.

23. A method of making a smoking article comprising mixing the cellulosic material of any one of claims 1-10 or the cellulosic material made by the method of any one of claims 11-20 with other cellulosic materials or smoking article ingredients.

24. Use of the cellulosic material of any one of claims 1-10 or the cellulosic material produced by any one of claims 11-20 in the manufacture of a smoking article.