GB2570162A

GB2570162A - Aerosol production element and method of manufacture

Info

Publication number: GB2570162A
Application number: GB1800664.3A
Authority: GB
Inventors: William John McLaughlin David; Robert Hopps Jason
Original assignee: Elucid8 Holdings Ltd
Current assignee: Elucid8 Holdings Ltd
Priority date: 2018-01-16
Filing date: 2018-01-16
Publication date: 2019-07-17
Also published as: GB201800664D0

Abstract

An aerosol production element for an aerosol-generating device comprises an active volatile substance 1 and a plurality of laminar sheets of material 23, of thickness ranging from 0.005mm to 1mm, separated from each other by a gap of 0.005mm to 1mm, optionally arranged as a cylindrical roll with a spiral cross-section, with a pressure drop of ≤100mmWC. The adjacent layers of laminar sheet are held apart by separating elements (7, fig 5). The separation of the sheets provides an increased surface area and optimised airflow path. A method of manufacture is also included.

Description

Aerosol production element and method of manufacture

Description

Many alternatives to traditional combustible tobacco products have been launched in recent years.

Electronic Cigarettes use battery power to heat a nicotine-containing aerosol-generating liquid to form an inhalable nicotine-containing aerosol. Such products tend not to contain tobacco.

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.

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.

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.

Consumables for heat-not-burn tobacco products rely upon the entrainment of volatile tobacco compounds, including nicotine and flavourants, into the aerosol. The process of entrainment increases with increased surface area and increased airflow path length as both provide more opportunities for volatile tobacco components to enter the airstream and be entrained within the aerosol. However, certain methods of increasing airflow path length and/or surface area tend to concomitantly increase pressure drop, i.e., the physical effort that consumers must input in order to obtain an inhalable puff from the product. Excessive increase in pressure drop could be a negative aspect of the overall consumer experience .

Additionally, filtration processes when present within the HNB consumable may negatively affect the amount of aerosol available to the consumer. For example, aerosol particles travelling through a section of generally spherical tobacco particles will tend to impact or be absorbed upon tobacco particles, especially where the tobacco particles are randomly dispersed within that space, or tightly packed with insufficient or tortuous airflow paths through it. The resultant number of aerosol particles in the aerosol available for inhalation by the consumer is therefore greatly reduced.

Additionally, as the tobacco particles may absorb the chemical components of aerosol particles during use, the physical structure of tobacco particles may change throughout the duration of use by the consumer. For example, available surface area for evaporation of tobacco components into the aerosol may diminish, and/or pH may become altered, which in turn will affect rates of evaporation of tobacco flavour components .

Pressure drop or draw resistance is measured using the CORESTA Recommended Method 41 (https://www.coresta.org/sites/default/files/ technical documents/main/CRM 41-update2 O.pdf) and expressed as millimetres water-column equivalent (mmWC). In relation to the current invention, a pressure drop of ^lOOmmWC would be desirable.

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.

Reconstituted tobacco sheet is widely used for manufacture of tobacco containing consumables within heat-not-burn products, partly because it offers improved chemical and physical uniformity compared to intact processed tobacco leaf particles. Often it is presented as a crimped sheet whereby a strip of sheet is gathered together to form a defined shape, typically a cylinder. For example W02012164009describes a reconstituted tobacco sheet material for use in heat-notburn products where the sheet is textured or crimped and US2016309781 describes a co-laminated sheet for use in aerosol-generating products, where the sheet is gathered together in a relatively random manner.

However, the crimping process can produce a non-uniform structure resulting in wider and narrower channels which in turn offer more preferable and less preferable airflow routes through the crimped material.

Improvements to physical properties of reconstituted tobacco sheet for use in smoked products have been explored, including:

US4291711 describes a reconstituted tobacco sheet uniformly embossed with a series of parallel grooves, with the potential effect of increasing available surface area, when used in a filter for a traditional combustible tobacco product.

FR2418628 also describes a manufacturing process for embossing or texturing reconstituted tobacco sheet material.

EP2081452 describes a laminate roll of tobacco and other materials intended for use in a smokeable product.

WQ2016050873 describes a corrugated reconstituted tobacco sheet for use in smoking products .

WQ2013034306 describes a reconstituted tobacco material spirally wound into a plug for use in a smoking article, with the central channel deliberately left open.

US20080245379 describes a manufacturing method for adding tobacco dust onto the surface of reconstituted tobacco sheet during its formation.

However, for application within a HNB consumable there remains further opportunity to provide an aerosol production region that is optimised for the entrainment of volatiles through:

(i) maximised surface area within a given volume and (ii) elongated and uniform airflow paths, whilst still maintaining an acceptably low pressure drop.

Therefore, the current invention describes means to maximise surface area for entrainment of volatile components from a sheet-like material, and of producing defined, elongated and uniform airflow paths across said material when formed into an aerosol generating element with acceptable pressure drop for use within a HNB consumable .

To optimise unimpeded airflow through the aerosol generating element, the aerosol generating material is presented as thin flat laminar sheets Figure 1, object 4, fixed substantially parallel to each other to form linear airflow channels 5 between adjacent layers. Such laminar sheet material may be formed from tobacco, or non-tobacco material, for example paper or another inert substance. Aerosol particles 1 can easily pass between adjacent layers of material 4 in the direction of airflow 2, with less chance of becoming impacted or absorbed, thus increasing the total amount of aerosol particles 3 available for inhalation by the consumer.

In a preferred embodiment, the substantially parallel laminar sheets of material are presented in the form of a cylinder with a spiral cross section, Figure 5. This embodiment has the further advantage that it can be readily formed by rolling a strip of laminar material.

To provide a uniform gap between adjacent layers of laminar material sufficient for airflow channels, separating elements (Figure 2, object 7) can be introduced. These may be in the form of solid elements fixed onto one or both surfaces of the laminar material or in the form of raised protrusions added to one or both sides of laminar material 6 using various suitable techniques such as printing, embossing and texturing. Alternatively, separating elements can be added during the formation process of the laminar material. For example, solid particles of tobacco can be introduced onto the surface of a reconstituted tobacco sheet material prior to drying. During the drying process, the tobacco particles become bound to the matrix of the tobacco sheet. The solid particles may be on the surface of the sheet material or at least partially embedded within the structure to provide better anchoring.

To provide additional source of volatile components for entrainment into the aerosol regions 8 between separating elements 6 can be coated with volatile producing material in solid, gel or liquid formats. Such volatile producing material may be plant-derived. Suitable plant-based materials can be obtained from tobacco plants or other plants with desirable volatile components such as mint, clove, cannabis, etc.

Figure 3 shows an alternative embodiment, where separating elements 7 are formed from multiple layers 7a of material successively printed onto laminar material 6. This has the additional benefit of allowing formation of alternative crosssectional shapes of separating elements.

Figure 4 shows an alternative embodiment, where separating elements 7 are formed on one side of the laminar material 6, and the opposite side of laminar material 6 is coated with plant-derived material 8.

Figure 6 shows an embodiment of the present invention wherein the laminar material 6 has separating elements 7 arranged as solid stripes in parallel lines to form discrete airflow channels from the distal end to the mouth end.

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

Separating elements 7 could be arranged randomly, regularly spaced, in continuous lines, in intermittent lines 10 or combinations thereof.

During use, airflow drawn by the consumer, if unimpeded, would tend to flow directly across the surface of the material taking the shortest possible route from distal end to mouth end, as shown by the direction and length of arrow 11. However, if separating elements 7 are produced at an offset angle 12 from the longitudinal axis 11, then airflow will be forced to take a proportionally longer route as shown by the length and direction of arrow 13. For example, by arranging separating elements at an angle of 45° to the longitudinal axis the airflow path is increased by 141% compared to the length of the longitudinal axis. Using an angle of 60° to the longitudinal axis increases the airflow path by 200%. Using an angle of 85° to the longitudinal axis increases the airflow path by 1100%.

Additionally, in Figure 6, separating elements 7a may have one angled change 12a in orientation along their length, which serves to further increase the airflow path 13a. In an alternative embodiment, separating elements 7b have more than one angled change in orientation, with a resultant increase in airflow path length 13b.

Figure 8 shows an alternative embodiment, wherein separating elements 7 are formed intermittently at a perpendicular angle to the longitudinal axis. Gaps 14 between separating elements 7 force airflow along a longer path 15. In this embodiment, the separating elements act as baffles to convolute the airflow pathway and increase residence time.

To provide the aerosol generating material in a compact three-dimensional shape suitable for inclusion within a consumable for use with a heating device, the laminar material can be rolled up to form a cylinder with essentially spiral cross-section, as shown in Figure 5. When used in the final product for consumption, during inhalation by the consumer, air would be drawn through channels 9 between separating elements 7, across the surface area of laminar material 6.

Figure 7 shows an outer view of the cylindrical aerosol generating element formed by wrapping the total material in Figure 6 into a spiral format. Figure 9 shows an outer view of the cylindrical aerosol generating element formed by wrapping the total material in Figure 8 into a spiral format.

Figure 10 shows an expanded cross-sectional view of the spiral sheet. Depending on the desired/available diameter 18 of the finished product, and the desired pressure drop, thickness 16 of the laminar material, and height 17 of the separating elements can be altered accordingly. The dimensions of channels 9 can be measured in the circumferential axis 17a, and the radial axis 17. The mathematical relationship between material physical properties and pressure drop can be summarised as follows:

Total pressure drop of an element = [Resistance due to laminar flow] + [resistance due to turbulent flow] + [resistance due to % occlusion]

Within a preferred embodiment of the present invention shown in figure 5 the contribution of laminar flow to total pressure drop tends towards zero due to the small cross-section of the individual airflow channel, whereas the contribution of turbulent flow tends to dominate the total pressure drop.

A preferred embodiment of the present invention uses a laminar material formed of reconstituted tobacco sheet with separating elements composed of tobacco particles, the total surface being finished with a coating of a flavouring and aerosol former. Tobacco grades for use in the production of all aspects of this embodiment are selected based upon desirable sensory characteristics and low levels of undesirable chemicals. Most preferably the tobacco complies with advised maximum levels of undesirables such as defined by the Gothiatek standard.

Preferably the laminar material is comprised of reconstituted tobacco sheet manufactured by the Fourdrinier process with tensile strength enhanced with the addition of 5~15% cellulose fibres. Preferably the chemical constituents of the tobacco are enhanced relative to the original tobacco by a process of washing, selectively removing undesirable components, concentrating the liquor and reapplying to the final material. Most preferably the pH of the reapplied liquor is adjusted to 8.5 to ensure optimum transfer of nicotine from the solid material into the inhaled aerosol.

Preferably separating elements are formed from tobacco particles. These particles are preferably manufactured from stem tobacco, ground using a hammer mill and sieved. Most preferably the fraction passing a 300 mesh sieve but not passing a 400 sieve are used to give an average particle size of 0.05mm with no particles over 0.075mm or under 0.025mm. Separating elements are formed by affixing tobacco particles onto one surface of the laminar material using a derivatised starchbased fixative. The fixative is applied in continuous narrow bands onto the surface of the laminar material, tobacco particles are added, pressed, then dried to activate the fixative. Non-adhered tobacco particles are then removed from the surface using compressed air.

Preferably separating elements are generated in parallel bands of 0.05mm width, 2.5mm apart, at an offset angle of 45° relative to the longitudinal axis of the aerosol production element and with a height of 0.05mm.

Preferably the laminar material and separating elements construction is then sprayed with a coating to enhance the desirable characteristics of the aerosol production element. Preferably the coating is comprised of flavouring, nicotine and aerosol former and applied at a rate of 1~5% weight of the laminar material. Preferably the flavouring is l~10% in a propylene glycol / glycerol base. Most preferably the coating is a solution of 5% menthol in a 50:50 propylene glycolglycerol mix applied at a rate of 1% dry weight of laminar material.

The printed laminar material is then rolled in a direction perpendicular to the longitudinal axis into a spiral comprising approximately 35 layers across an external diameter of 7.5mm. Using such an approach, a laminar material of width 390mm can be contained within a small cross-sectional area suitable for use within a HNB consumable.

Using separating elements between adjacent layers, both sides of the material are available to emit volatile components into the airflow for entrainment into the inhalable aerosol. This spiral arrangement has the further advantage that the airflow paths are well defined and regular in shape, which is preferable to control pressure drop. Individual airflow channels will have similar cross-section and length and hence similar pressure drop. Using this construction, the total pressure drop of the tobacco section in this preferred embodiment is in the range 40 to 50 mm water column for a 19mm long section.

To assist with initial formation of the spiral format during manufacture, and to prevent the occurrence of an excessively large airflow channel through the centre of the spiral, in one embodiment of the invention (Figure 11), it is preferable to use a central forming rod 19. Such forming rods could be composed of any suitable inert material with sufficient strength, for example glass, metals such as aluminium, carbon fibre, cardboard, plastics such as polyamide, laminates and combinations thereof. Preferably the forming rod is composed of carbon fibre of circular cross-section with 1mm diameter. Laminar material 6 is initially fixed to forming rod 19 with a thin line of fixative 20. Suitable fixatives may be selected based on physical strength, drying time, and toxicological properties, for example polyvinyl alcohol or starch-based adhesives. In an alternative embodiment, as shown in Figure 12, laminar material 6 is initially folded or crimped to form a rigid forming rod core 21.

The spirally-rolled laminar material is suitable for use as an aerosol production element. Such an element may be used in a variety of ways to produce or modify an aerosol for inhalation by consumers within consumable portions for heat-notburn products. Such consumable portions are intended for a limited number of usage occasions by the consumer, typically only one usage occasion comprising of 10-20 individual inhalation puffs.

For example, in Figure 13, aerosol production element material 23 is placed downstream from heater unit 22 which emits aerosol particles 1 by evaporating aerosol-generating materials such as propylene glycol, glycerol, or polyethylene glycol. As aerosol particles 1 travel through aerosol production element 23, volatile components from the aerosol production element 23 become associated with aerosol particles 1, forming modified aerosol particles 3, which are then inhaled by the consumer.

In an alternative embodiment of use, as shown in Figure 14, aerosol production element 23 can be directly heated with external heating elements 24, internal heating element 25 and combinations thereof. Aerosol production element 23 may contain aerosol-producing agents such as propylene glycol, glycerol or polyethylene glycol. Upon heating of aerosol production element 23 to a predetermined temperature, the aerosol producing agents form aerosol particles 3 for inhalation, which also contain active volatile substances derived from other ingredients that have been manufactured into aerosol production element 23.

Active volatile substances are components of plant material or plant extract, or synthetic chemicals, evaporated/inhaled . extracts of tobacco that produce pharmacological or sensorial effects when Active volatile substances can be tobacco, marijuana, or marijuana (by water or organic solvent), nicotine, caffeine, taurine, clove, cannabidiol, menthol and combinations thereof.

Claims

1. An aerosol production element comprising an active volatile substance and a plurality of laminar sheets of material of thickness ranging from 0.005mm to 1mm separated from each other by a gap of 0.005mm to 1mm, with a pressure drop of less than 100mm water column.

2. An aerosol production element according to claim 1 comprising an active volatile substance and a plurality of laminar sheets of material of thickness ranging from 0.005mm to 1mm separated from each other by a gap of 0.005mm to 1mm, with a pressure drop of less than 50mm water column.

3. An aerosol production element according to any preceding claim wherein the plurality of laminar sheets is formed from at least one laminar sheet arranged as a cylindrical roll with a spiral crosssection .

4. An aerosol production element according to any preceding claim wherein the airflow channels formed within the gap between adjacent laminar sheets are of length 120% to 1100% of the longitudinal axial length of the aerosol production element.

5. An aerosol production element according to any preceding claim wherein the length of all airflow channels therein have a relative standard deviation of less than 10%.

6. An aerosol production element according to any preceding claim wherein individual airflow channels are of consistent cross-section size from the distal end to the mouth end, measurement in the radial direction having a relative standard deviation of less than 20% and measurement in the circumferential direction having a relative standard deviation less than 20%.

7. An aerosol production element according to any preceding claim wherein adjacent layers of laminar sheet are held apart by separating elements .

8. A separating element according to any preceding claim that is comprised of multiple layers.

9. An aerosol production element according to any preceding claim wherein the separating elements are arranged to form at least one continuous airflow channel between adjacent laminar sheets from the distal end to the mouth end.

10. An aerosol production element according to any preceding claim wherein the separating elements are arranged at an angle of 5° to 90° relative to the longitudinal axis.

11. An aerosol production element according to any preceding claim wherein the separating elements are spatially arranged relative to each other to prevent the occurrence of a linear airflow channel from the distal end to the mouth end.

12. An aerosol production element according to any preceding claim wherein the separating elements have one or more angled changes in orientation along their length.

13. An aerosol production element according to any preceding claim that contains a central forming rod.

14. The use of an aerosol production element according to any preceding claim within a consumable for use with a heating device to produce an inhalable aerosol.

15. A process for manufacturing an aerosol production element according to any preceding claim by fixing separating elements onto a base layer of material using a fixative and rolling the material to form a cylinder with a spiral cross-section

Intellectual Property Office

Application No: GB1800664.3

Examiner: Mrs Margaret Phillips

Claims searched: 1-15

Date of search: 29 January 2019

Patents Act 1977: Search Report under Section 17

Documents considered to be relevant:

Category Relevant to claims Identity of document and passage or figure of particular relevance X 1-3, 5, 6, 13-15 WO 96/07336 A2 (BRITISH AMERICAN TOBACCO COMPANY) See fig 1 & la, and page 31 para 3 X 1,2, 5,6 13, 14 WO 2015/082649 Al (PHILIPS MORRIS PRODUCTS) See fig 1 and associated description X 1,2, 5,6 13, 14 WO 2016/050706 Al (PHILIPS MORRIS PRODUCTS) See fig 1 and associated description X 1,2, 5,6 13, 14 WO 2015/082653 Al (PHILLIPS MORRIS PRODUCTS) See fig 3 and associated description