GB2569964A

GB2569964A - Aerosol production system

Info

Publication number: GB2569964A
Application number: GB1800105.7A
Authority: GB
Inventors: William John McLaughlin David; Robert Hopps Jason
Original assignee: Elucid8 Holdings Ltd
Current assignee: Elucid8 Holdings Ltd
Priority date: 2018-01-04
Filing date: 2018-01-04
Publication date: 2019-07-10
Also published as: GB201800105D0

Abstract

An aerosolisation system comprising a vapourisation means 4 which generates a first aerosol and a flavouring means wherein the entrainment of volatile compounds from the flavouring material 6a into a first aerosol is increased by close proximity of said means and/or use of insulating materials. The temperature drop from a heating element 3 within the vaporisation system to the flavouring means is less than 100°C. The flavouring means may be in close proximity, preferably less than 3mm from the heating element. Alternatively, the heating element may be surrounded by the flavouring means for at least 80% of its surface area or the flavouring means by be surrounded by insulating material. Also claimed is a flavouring means containing a laminar sheet of tobacco-derived material of porosity more than 1000 CORESTA units and a method of manufacturing a flavouring means by introducing holes into a laminar sheet of tobacco-derived material, shaping the material and drying to a final moisture content of less than 15%.

Description

Aerosol production system

Description

There are several alternatives to traditional tobacco products which are becoming increasingly popular. Heat-not-burn (HNB) tobacco products typically employ an energy source to heat a tobacco-containing consumable and thereby generate an inhalable aerosol that contains volatile components derived from tobacco, notably flavour and nicotine.

Electronic cigarettes employ an energy source to vapourise a liquid typically comprising a mixture of glycerol, propylene glycol, flavour and nicotine to form an inhalable aerosol.

There are also various "hybrid" products which can combine technology from both electronic cigarettes and heat-not-burn tobacco products to generate an inhalable nicotine-containing aerosol wherein flavour and nicotine can originate from either the aerosol-generating liquid or the tobacco portions or both.

Specific examples of existing technologies include: WO9639880 and W02013190036 describe a cigarette-like cylindrical consumable article, with a distal end containing tobacco-derived material, typically crimped reconstituted tobacco sheet, a mouth-end filter typically containing multiple segments, and an overwrap made from paper. Said article is intended to be electrically heated to produce an inhalable nicotine-containing aerosol. W02016207407 also describes a tobacco consumable intended for consumption by heating, namely a distal tobacco-derived portion, a mouth-end filter and a paper overwrap . W02016159013 describes a device in which an aerosol is generated by heating a liquid which is then passed through a separate tobacco portion; the tobacco portion imparts flavour and/or nicotine to the final aerosol. The tobacco portion can be held within a moulded plastic capsule with a mesh at the distal end and a small filter at the mouth-end. WO2016135342 describes a product which operates in a similar manner to that described in W02016159013, however the tobacco portion and the liquid heating unit are comprised as one unit. The tobacco portion is held within a moulded plastic structure with a filter at the mouth-end.

The term aerosol shall be interpreted to include gas, vapour, droplets, condensates, particulates and combinations thereof. An inhalable aerosol shall mean an aerosol with an average particle size as measured by laser dispersion ranging from 0.1 to 10 pm, more preferably 0.1 to 1.5 pm.

Referring to Figure 1, a vapourisation means 4 is a system that converts a liquid into an aerosol. It comprises a liquid transport means 2 and a heating means 3. A liquid transport means 2 is in fluid connection with a liquid storage means 1 and a heating means 3. A liquid transport means 2 may be comprised of a wicking material, fibres, tube, tubes, capillaries and combinations thereof.

Also in Figure 1, a flavouring means 8 is an element that imparts sensory enhancement to a first aerosol 5. Preferably a flavouring means comprises an external envelope 7 and a flavouring material 6 which contains volatile compounds which enhance the aerosol. Sensory enhancement may be flavour, aroma, active volatile substance or combination thereof. Active volatile substances are components of plant material or plant extract, or synthetic chemicals, that produce pharmacological or sensorial effects when evaporated/inhaled. Active volatile substances may be extracts of tobacco, nicotine, caffeine, taurine, clove, cannabidiol, menthol and combinations thereof. Sensory enhancement may be derived from a solid, liquid, gel or combinations thereof. Preferably a flavouring means 8 contains a tobacco-derived flavouring material. A heating means 3 is a means to convert electrical energy into heat energy. A heating means 3 may be comprised of a resistive element. A resistive element may be comprised of metal, alloy, ceramic or combinations thereof.

The mouth end 12 is the end of the aerosol production element intended to act as an exit for an inhalable aerosol 9 towards the user. The distal end 11 of the flavouring means 8 is the end intended to act as an entry point for air and other materials to flow in. The longitudinal axis 10 runs from the distal end to the mouth end. Other axes are taken as perpendicular to the longitudinal axis.

Hybrid products typically produce a first aerosol 5 by heating an e-liquid often containing glycerol and propylene glycol using a vapourisation means 4. This first aerosol 5 is then passed through a region of tobacco or tobacco-derived flavouring material within a flavouring means 8 to produce a final inhalable aerosol 9 which is inhaled by the user. Hence in hybrid products there is no heat source applied directly to the flavouring means. Often hybrid products utilise a non-flavoured, zero nicotine e-liquid to produce the first aerosol 5, and hence rely upon the entrainment of volatile compounds from the tobacco portion to provide desirable taste and sensorial attributes to the inhalable aerosol 9.

In hybrid products, the heating process to generate the first aerosol 5 is separate from the entrainment process which imparts flavour and nicotine to the inhalable aerosol 9. A lack of heating during the entrainment process places a number of limitations upon the efficiency of the entrainment process, which in turn negatively affects the desirability of the inhalable aerosol 9.

Nicotine and other flavour molecules important to the overall sensorial experience of using hybrid products typically have boiling points >200°C. Typically, the temperature reached within the tobacco-containing portion during use is 50~100°C, resulting in poor vapourisation of nicotine, which in turn leads to poor entrainment of nicotine into the inhalable aerosol 9.

Vapour pressure of a volatile compound is characterised by an exponential relationship to absolute temperature, as described by the Antoine equation:

Log P = A - B(C+T)

Where P = vapour pressure, T = temperature, and A, B and C are constants for individual compounds known to those skilled in the art.

Hence, small increases in temperature can result in a significant increase vapour pressure. The vapour pressure of a compound can be used a good first approximation of the relative amount of compound available for entrainment at different temperatures .

For illustration, Figure 2 shows vapour pressure data at a range of temperatures for two model compounds, nicotine and menthol.

Many desirable flavour molecules have similar boiling points (b.p.), and hence within a hybrid product, a similar low percentage will be available for entrainment. Example flavour molecules could include piperonal b.p. 263°C, vanillin b.p. 285°C, cinnamaldehyde b.p. 248°C.

To generate a more desirable sensorial experience, it is beneficial to enhance the vapour pressure of volatile components within the tobacco-containing portion of the flavouring means and thereby enhancing the entrainment process.

For example, by increasing the temperature of the tobacco-derived portion by 50°C from 125°C to 175°C, the vapour pressure of nicotine increases over fourfold, with a coincident increase in the amount of nicotine available for entrainment within the inhalable aerosol.

The present invention overcomes the limitation of current hybrid tobacco products by increasing the percentage of heat energy available within the tobacco portion relative to the total heat energy generated within the system. This is achieved by reducing the amount of heat energy lost to the environment as waste heat.

Within hybrid products, heat energy is generated within a vapourisation means 4 by converting electrical energy from the battery using a resistive metallic or ceramic element. This heat energy is used to convert the e-liquid into a gas; the gas quickly cools to form fine liquid droplets which are visible. Of the total energy put into the complete system, much is lost to the environment as wasted heat from the device body.

By minimising the distance between the heating means 3 and the tobacco-derived flavouring material 6, significantly more of the total heat energy used in the vapourisation process can be transferred to the tobacco-derived flavouring material and used to drive off volatile components to be entrained into the final inhalable aerosol 9. This arrangement means that a single heating means 3 is sufficient to produce first aerosol 5 and to assist aerosol enhancement by simultaneously heating flavouring means 8. Efficient use of only a single heating means avoids unnecessary increase in size of the overall system if more than one heating means is employed, thereby maintaining convenience for consumers.

In a preferred embodiment of the present invention, Figure 3, the heating means 3 is positioned within the tobacco-derived flavouring material 6a, thus heat energy that would otherwise lost to the surroundings via the external walls is absorbed by the tobacco-derived material 6a. Heating means 3 is contained within, and where necessary electrically insulated from, a piercing element 13. Piercing element 13 may be a cylinder composed of stainless steel, and also carries electrical connector wires 14, and liquid transporting means 2 which carries e-liquid from reservoir 1 to heat source 3. Most preferably the heat source is positioned centrally within the tobacco-derived flavouring material so that heat losses to the environment in all directions are minimised.

Heat losses to the environment can also be minimised by the use of an insulation region 16 between the tobacco-derived flavouring material 6a and the external environment. Such an insulating region 16 may be comprised of one or more materials with low thermal conductivity such as aerogels, expanded / foamed plastics, fibrous materials; reflective materials such as highly polished aluminium foil; regions of vacuum and combinations thereof. The insulation region 16 can be part of the flavouring means 8, part of the exterior wall (figure 4, part 35) of a reusable device, or a combination thereof.

In a preferred embodiment, Figure 4, the consumable flavouring means 8 fits inside a receiving portion 35 of a reusable device. The region of the device that immediately surrounds the consumable is insulated 16, thereby retaining heat energy within the flavouring means. Most preferably, the insulation 16 is a composite of aluminium foil and a dense polyurethane foam with thermal conductivity less than or equal to 0.03W/(m K).

The entrainment process is also affected by the amount of contact between the first aerosol 5 and the tobacco-derived flavouring material 6. It is desirable to have the tobacco-derived flavouring material 6 arranged in such a manner to achieve a regular and elongated pathway to ensure maximal entrainment.

In a preferred embodiment, Figure 3, the first aerosol 5 is provided from a central heating means element 3 within a cylinder of tobacco-derived flavouring material 6a. In this embodiment the aerosol 5 moves in a radially outward direction through the tobacco-derived flavouring material 6a.

In an alternate preferred embodiment, Figure 5, the first aerosol 5 is provided at one side of the tobacco-derived flavouring material 6b and the aerosol moves laterally across the tobacco-derived material in the direction of arrow 17. These arrangements ensure the path length of the first aerosol 5 across the tobacco-derived flavouring material 6b is consistent, creating a consistent inhalable aerosol.

The tobacco-derived flavouring material can include single-grade tobacco, blended tobacco grades, leaf, stem, dust, reconstituted tobacco, washed tobacco, extracted tobacco, treated tobacco, tobacco extracts and mixtures thereof. The tobacco-derived flavouring material can be produced from tobacco plants by methods including harvesting, drying, cutting, shredding, grinding, extraction, reconstitution, extrusion and combinations thereof. The tobacco-derived flavouring material can be present in the physical form of leaf, stem, dust, reconstituted sheet, crimped, folded, shaped, beaded, granulated and mixtures thereof.

In a preferred embodiment, the tobacco-derived flavouring material is presented in the form of regularly sized granules or beads. Such tobacco containing granules are preferably produced by extrusion.

In an alternate preferred embodiment, the tobacco-derived flavouring material is presented in the form of folded reconstituted sheet material 6c arranged in a radial pattern, as shown in Figure 6. This arrangement provides a high surface area within a defined structure, which has the benefit of producing a consistent entrainment into the first aerosol 5. It also ensures that the first aerosol 5 must pass through the structure of the tobacco-derived flavouring material 6c prior to being inhaled. Heat source 3 is wrapped around liquid-transporting means 2, which are contained within the structure of tobacco sheet material 6c.

To prevent too high a pressure drop from occurring in this radial arrangement of sheet material 6c, it is preferable to have perforations within the sheet material which act as paths of lower resistance for the aerosol to travel. Perforations can be introduced as holes created in the material by mechanical means such as pins, punches, knives; by using jets of fluid such as air or water or combinations thereof. Perforations may be introduced during the manufacture of the sheet material or post manufacture or a combination thereof. Preferably perforations are introduced to increase the average porosity of the sheet material above 5000 CORESTA units (CU). Using such a porous sheet ensures the aerosol can travel in a direction perpendicular to the main axis of the sheet material.

Within the consumable portion of hybrid products, the vapourisation means 4 to produce the first aerosol 5, and the flavouring means 8 can be supplied as a single integral unit (for example, Figure 6) . In an alternative arrangement, the vapourisation means 4 and the flavouring means 8 are separable (for example, Figures 3 & 4), which has the advantage that the two units can be replaced independently, giving more flexibility.

Figure 8 shows alternative embodiments of the piercing element 13. Cross-section 24 of piercing element 13 can be substantially cylindrical 26, substantially elliptical 25 or substantially rectangular 27, or any combinations thereof along its length. The holes through which aerosol emerges from piercing element 13 can be of various shapes and locations. For example, there may be a single hole 28 at the end of piercing element 13. Alternatively, there may be more than one hole 29 along the side walls of piercing element 13, which can be formed at an angle 23 relative to the longitudinal axis 10. Depending on angle 23, first aerosol 5 exiting from holes 29/30 may be directed along the most efficient path through tobacco-derived flavouring material 6a so as to optimise entrainment. Holes can be of differing size 30 to aid more consistent dispersion of aerosol into tobacco-derived flavouring material 6a.

An alternative preferred embodiment of the present invention is shown in Figure 7. A vapourisation means 4 comprising a stainless steel outer housing 35, a liquid transport means 2 composed of a 2mm diameter bundle of glass fibres of individual diameter <10pm, a heating means 3 comprising a helical coil of an 80:20 nickel/chromium alloy resistive heating wire of resistance 1Ω with a polyimide coating acting as an electrical insulator. The electrical connection wires 14 are made of nickel with a PVDF outer sheath. The heating means 3 is housed within a cylindrical stainless steel piercing element 13 of wall thickness 0.5mm within a cylinder of tobacco-derived flavouring material 6a. The tobacco-derived flavouring material 6a is contained within a cylinder of polyurethane with thermal coefficient of 0.03 W/(mK) with an outer layer of aluminium foil of thickness 25pm, finished in a transparent layer of PET.

In a preferred embodiment, the liquid used is a mixture of 75% propylene glycol and 25% glycerol, with no added flavours or nicotine.

In a preferred embodiment of the present invention, the tobacco-derived flavouring material 6a is generated by providing a blend of tobacco grades comprising flue cured and air-cured tobaccos with a chemical composition in accordance to Gothiatek® Standard, namely tobacco-specific nitrosamine (NNN + NNK) content of <lmg/kg and benzo[a]pyrene content of <1.25ug/Kg. Once blended, the tobacco is reduced in size by first shredding and then grinding to pass through a No.18 Mesh giving a particle size of =<lmm. To the ground tobacco is added 50% equivalent mass of deionised water; 2% equivalent mass of flavourant - a 50:50 mix of menthol and mint oils; 0.375% equivalent mass pH modifying agent - sodium hydroxide. The resultant tobacco paste is passed through a Coperion extruder with barrel temperature 250°C and pressure 4atm linked to a pelletizer to produce a shaped material of particle size approximately 1.5mm diameter. The tobacco-derived particles are then dried under vacuum to <10% moisture. The dried tobacco particles are then sieved to produce a fraction in the range 0.2mm ~ 1.25mm.

Figure 6 shows an alternative preferred embodiment where the tobacco-derived flavouring material is in the form of a folded sheet 6c. In this embodiment, the tobacco sheet 6c is formed using the same input tobacco and initial processing as outlined above, but is ground such that it will pass through a No.35 Mesh / <0.5mm particle size. 6% cellulose fibres are added to the flavoured tobacco mix prior to addition of the base. After the addition of the sodium hydroxide, the resultant tobacco paste is then spread out to form a layer of thickness 0.5mm and dried using infra-red heating to a moisture of 15%~20%. The porosity of this material is increased to 12,500CU by using a series of pin rollers to generate holes of average diameter 0.1mm. This sheet material is then folded to form a pleated structure of height 3mm. The pleated sheet is then further dried to a final moisture of 10%.

Figure 5 shows a cross-section of an alternative embodiment where the heating means 3a and tobacco-derived flavouring material 6b are substantially planar and in close contact. Heating means 3a may be a porous membrane comprised of nichrome wire embedded in polyimide, or a porous stainless-steel foil. The liquid transport means 2 is a 3mm layer of wicking material, preferably Japanese cotton. The tobacco-derived flavouring material 6b comprises tobacco-derived sheet material prepared as described previously, arranged in a stack of multiple layers, preferably at least 5 layers. The tobacco-derived flavouring material 6b is porous to allow the passage of aerosol perpendicular to the orientation of the sheet. Preferably the tobacco sheet material has a porosity of 12,500CU with an average hole diameter of 0.1mm.

During use, heating means 3a evaporates e-liquid from liquid transport means 2, and air is drawn in direction of arrow 17, which carries aerosol particles through pores in tobacco-derived flavouring material 6b, wherein volatile components from the tobacco-derived flavouring material 6b become associated with aerosol particles, forming inhalable aerosol 9.

Claims

1. An aerosolisation system comprising a vapourisation means and a flavouring means wherein the temperature drop during use from the heating means within the vapourisation means to the flavouring material within the flavouring means is less than 100°C.

2. An aerosolisation system comprising a vapourisation means and a flavouring means according to claim 1 wherein the temperature drop during use from heating means within the vapourisation means to the flavouring material within the flavouring means is less than 50°C.

3. An aerosolisation system comprising a vapourisation means and a flavouring means according to any preceding claim wherein at least 25% of heat energy generated by the heating means transfers to the flavouring material.

4. An aerosolisation system comprising a vapourisation means and a flavouring means according to any preceding claim wherein at least 50% of heat energy generated by the heating means transfers to the flavouring material.

5. An aerosolisation system comprising a vapourisation means and a flavouring means according to any preceding claim wherein the heating means is <8mm from the flavouring material.

6. An aerosolisation system comprising a vapourisation means and a flavouring means according to any preceding claim wherein the heating means is <3mm from the flavouring material.

7. An aerosolisation system according to any preceding claim wherein the heating means is surrounded by the flavouring means for at least 50% of its surface area.

8. An aerosolisation system according to any preceding claim wherein the heating means is surrounded by the flavouring means for at least 80% of its surface area.

9. An aerosolisation system according to any preceding claim wherein the flavouring means is surrounded by a region of thermal conductivity of <0.08W/(mK) for at least 75% of its surface area.

10. An aerosolisation system according to any preceding claim wherein the flavouring material forms a porous barrier to the first aerosol such that the first aerosol must pass through the structure of the flavouring material prior to being inhaled.

11. A flavouring means according to any preceding claim containing at least one laminar sheet of tobacco-derived material of porosity more than 1,000 CORESTA units.

12. A flavouring means according to any preceding claim containing at least one laminar sheet of tobacco-derived material of porosity more than 10,000 CORESTA units.

13. A flavouring means according to any preceding claim containing at least one laminar sheet of flavouring material that is folded, pleated or crimped.

14 . A vapourisation means according to any preceding claim that has a least one vapour exit hole, such that vapour exits at an angle of greater than 10° to the longitudinal axis.

15. The process of manufacturing a flavouring material according to any preceding claim by providing a laminar sheet of tobacco-derived material of moisture <50%, introducing holes into the material of diameter <lmm, shaping the material and drying to a final moisture of <15%.