WO2013020833A2

WO2013020833A2 - Capsule formation

Info

Publication number: WO2013020833A2
Application number: PCT/EP2012/064781
Authority: WO
Inventors: Robert WHIFFEN
Original assignee: British American Tobacco (Investments) Limited
Priority date: 2011-08-10
Filing date: 2012-07-27
Publication date: 2013-02-14
Also published as: EP2741849A2; WO2013020833A3; GB201113774D0; US20140166026A1

Abstract

A capsule forming apparatus comprising a first support in which a plurality of first outputs configured to output a first capsule material are located; a second support in which a plurality of second outputs configured to output a second capsule material are located; and a second capsule material feed region between the first and second supports from which the second capsule material can enter the second outputs. A method of forming capsules is also described.

Description

Capsule formation Field

The invention relates to the formation of capsules. Particularly, but not exclusively, the invention relates to an apparatus and method for forming capsules with a core encapsulated by a shell. The capsules may be for use in the tobacco industry.

Background

As used herein, the term "smoking article" includes any tobacco industry product and includes smokeable products such as cigarettes, cigars and cigarillos whether based on tobacco, tobacco derivatives, expanded tobacco, reconstituted tobacco or tobacco substitutes and also heat-not-burn products.

Capsules can be incorporated into cigarettes and other smoking articles. For example, one or more breakable flavour capsules can be positioned inside the filter of a cigarette to allow a smoker to make a flavour selection before or during smoking. Generally speaking, the capsules are broken by squeezing the filter between finger and thumb to cause a flavour substance which was previously contained within the capsule to be released into the filter.

Equipment used to manufacture capsules for the tobacco industry includes, for example, a dual nozzle through which core material and shell material are fed simultaneously. The core and shell materials are supplied from separate containers, which are exclusively connected to the dual nozzle via separate feeds. A cooling fluid system, also exclusive to the dual nozzle, is used to cool a core/ shell combination which exits the nozzles.

The invention provides an improved process and apparatus for manufacturing capsules. Summary

According to the invention, there is provided a capsule forming apparatus comprising: a first support in which a plurality of first outputs configured to output a first capsule material are located; a second support in which a plurality of second outputs configured to output a second capsule material are located; and a second capsule material feed region between the first and second supports from which the second capsule material can enter the second outputs.

The second capsule material feed region may comprise a gap between the first and second supports.

Each of the first outputs may comprise a first nozzle and each of the second outputs may comprise a second nozzle. Each first output may extend at least partially into one of the second outputs to form a pair of outputs.

The first support may be substantially parallel to the second support. The first support may comprise a first substantially elongate member through which the first outputs extend and the second support may comprise a second substantially elongate member through which the second outputs extend.

The first support may comprise an upper plate which connects all of the first outputs together and the second support may comprise a lower plate which connects all of the second outputs together.

Boundaries of the shell material feed region may be impermeable to the shell material.

Boundaries of the shell material feed region may comprise surfaces of the supports. The apparatus may be configured to feed the first capsule material to the first outputs in a substantially downward, vertical direction.

The apparatus may be configured to feed the second capsule material to the second outputs in a substantially horizontal direction.

The apparatus may be configured to feed the first capsule material to the first outputs in a direction substantially parallel to a principal output direction of the first outputs.

The apparatus may be configured to feed the second capsule material to the second outputs in a direction substantially perpendicular to a principal output direction of the second outputs. The capsule materials output by the outputs may comprise droplets having an inner core of the first capsule material and an outer shell layer of the second capsule material.

The first capsule material may comprise a capsule core material and the second capsule material may comprise a capsule shell material.

The apparatus may comprise a vibration unit configured to vibrate a plurality of the first outputs or a plurality of the second outputs or both. The apparatus may further comprise a body of fluid into which the outputs are configured to output the capsule materials, the fluid being configured to harden the second capsule material.

The apparatus may comprise a fluid director configured to cause the capsule materials to follow a spiral path in the fluid. The apparatus may comprise a looped system around which the fluid is driven to and from the outputs.

The apparatus may comprise a cooling unit configured to cool the fluid to a temperature sufficiently low to solidify at least one of the capsule materials.

According to the invention, there is provided a capsule forming apparatus comprising: a capsule material output configured to output capsule material into a body of fluid; and a fluid flow director configured to create a flow of fluid which causes outputted capsule material to follow a spiral path in the body of fluid.

The fluid may be configured to harden the capsule material.

According to the invention, there may be provided a method of forming capsules comprising: supplying a first capsule material to a plurality of first outputs located in a first support; supplying a second capsule material to a plurality of second outputs located in a second support, comprising supplying the second capsule material via a second capsule material feed region located between the first and second supports; and outputting a droplet comprising the first capsule material and the second capsule material from a combination of the first and second outputs.

The droplet may comprise a liquid core of the first capsule material surrounded by a liquid layer of the second capsule material, and the method may further comprise hardening the second capsule material to form a shell around the liquid core.

According to the invention, there may be provided a capsule formed according to the method defined above.

For the purposes of example only, embodiments of the invention will now be described with reference to the accompanying figures in which:

Brief description of the figures Figure 1 is a schematic illustration of an apparatus for forming tobacco industry capsules in which upper and lower supports containing upper and lower groups of nozzles are configured to vibrate;

Figure 2 is an illustration of a tobacco industry capsule comprising an outer shell and an inner, liquid core.

Figure 3 is a schematic illustration of a pair of concentric nozzles for outputting liquid core and shell material;

Figure 4 is a flow diagram of a method for forming capsules;

Figure 5 is a schematic illustration of a nozzle apparatus and a fluid flow system for forming capsules. The nozzles are immersed in the fluid, which is driven longitudinally past the nozzles;

Figure 6 is a schematic illustration of a nozzle apparatus and a fluid flow system for forming capsules. The nozzles are immersed in the fluid, which is driven so that capsules follow a spiral path in the fluid; and

Figure 7 is a schematic illustration of a nozzle apparatus and a fluid flow system for forming capsules. The nozzles are immersed in the fluid, which is driven so that capsules follow a spiral path in the fluid. The fluid flows in a looped circuit and is cooled by a cooling unit. Detailed description

An apparatus for forming a capsule 1 which is suitable for incorporating into a cigarette or other smoking article is shown in figure 1.

The following description generally refers to a capsule 1 having a substantially spherical core 2 and a substantially spherical shell 3 which encapsulates the core 2. An example of the capsule 1 is illustrated in figure 2. However, as will be explained below, other shapes of capsule 1 can also be produced. In terms of size, the core 2 will generally have a diameter in the range of between approximately 0.5mm and approximately 5mm. An example diameter is 3.3mm. The shell 3 will generally have a thickness of between approximately 0.01mm and approximately 1mm. An example thickness is 0.1mm. It should be understood, however, that the invention is not limited to forming capsules 1 with cores 2 and shells 3 within these size ranges. Capsules 1 with cores 2 and/or shells 3 with sizes which are bigger or smaller than those given above can also be formed. As will be explained below, the core material 2 may be volatile and may be formulated to include a flavour compound such as menthol. One skilled in the art will appreciate that a variety of different flavours could be formulated to be included in a suitable core material 2. The flavour contained in the capsules 1 is released at a required time, for example when the shell 3 of the capsule 1 is perforated or crushed.

Referring to figure 1, the apparatus 4 for forming capsules 1 comprises a plurality of first capsule material outputs 5. In the discussion below, the first capsule material outputs 5 are configured to output capsule core material 2 and can thus be referred to as core material outputs 5. Each core material output 5 can, for example, comprise a nozzle 5 configured to receive liquid core material 2 at its entry and output core material 2 at its exit. The flow of core material 2 through the nozzle 5 to the nozzle exit can be caused by gravity or can be aided by the action of a pump. The core material outputs 5 will hereinafter be referred to as nozzles 5, although other types of output 5 could alternatively be used.

The apparatus 4 for forming capsules 1 also comprises a plurality of second capsule material outputs 6. In a similar manner to the core material outputs 5, the second capsule material outputs 6 are configured to output capsule shell material 6 and can thus be referred to as shell material outputs 6. Each shell material output 6 can, for example, comprise a nozzle 6 configured to receive liquid shell material 3 at its entry and output shell material 3 at its exit. The flow of shell material 3 through the nozzle 6 to the nozzle exit can be caused by gravity or can be aided by the action of a pump. The shell material outputs 6 will hereinafter be referred to as nozzles 6, although other types of output 6 could alternatively be used.

The arrangement and operation of the core and shell material nozzles 5, 6 will now be described. The core material nozzles 5 are supported by a first support 7, which in figure 1 is illustrated as comprising a first plate 7 lying in a substantially horizontal plane. In the discussion below the first support 7 will be referred to in this context, although other types of support are equally possible. The support 7 interconnects the core material nozzles 5 so that movement or vibration of the support 7 causes a corresponding movement or vibration of the nozzles 5. For example, the nozzles 5 and the support 7 may be formed as a one-piece unit using suitable techniques such as moulding or casting. Alternatively, the support 7 may comprise apertures into which the nozzles 5 are subsequently inserted. The nozzles 5 may be fixed in the apertures. Seals may be provided at the joins between the apertures and the nozzles to prevent material leakage. Each nozzle 5 comprises a pathway or aperture through which core material 2 can pass through the support 7 from one side to the other. In a similar manner to the core material nozzles 5, the shell material nozzles 6 are supported by a second support 8. As with the first support 7, the second support 8 interconnects the nozzles 6 and retains them in their intended position in the apparatus 4. In the example of figure 1 and the discussion below, the second support 8 comprises a second plate 8 which lies in a substantially horizontal plane substantially parallel to the main plane of the first plate 7 referred to above. Each shell material nozzle 6 comprises a pathway or aperture through which shell material can pass through the plate 8 from one side to the other. As with the first support 7, the second support plate 8 joins the plurality of shell material nozzles 6 together so that a movement or vibration of the plate 8 causes a corresponding movement or vibration in each of the nozzles 6. Furthermore, as with the first support 7, the shell material nozzles 6 and the second support 8 may be formed as a one-piece unit using suitable techniques such as moulding or casting. Alternatively, the support 7 may comprise apertures into which the nozzles 5 are subsequently inserted as previously described.

The first and second plates 7, 8 referred to above may be substantially rigid and can be formed of any suitable material. As is shown in the figures and will be explained in detail below, the first support plate 7 and core material nozzles 5 are located directly above the second support plate 8. The first and second plates 7, 8 will therefore be respectively referred to below as upper and lower plates 7, 8.

The core material nozzles 5 may extend at least partially into the shell material nozzles 6 which are located beneath them. Core material 2 entering the core material nozzles 5 passes under gravity through the core material nozzles 5 into the shell material nozzles 6 beneath.

Core material 2 in liquid form may be fed into the entries of the core material nozzles 5 by any suitable means. For example, a reservoir 9 of core liquid 2 may be located in the apparatus 4 above the upper support plate 7 so that the core liquid 2 can flow into the core material nozzles 5 under gravity. The reservoir 9 may be located directly above the support plate 7 to reduce the footprint of the apparatus 4. The reservoir 9 may comprise any suitable container for holding the core liquid 2. For example, in figure 1 , the reservoir 9 comprises a manifold 9 from which the core material 2 is fed towards the core material nozzles 5. Other types of tank 9 can alternatively be used. Optionally, the entry of each of the core material nozzles 5 is connected to the reservoir 9 by a conduit 10, such as a flexible hose, so that liquid core material 2 can flow through the conduits 10 to the core material nozzles 5. To prevent leakage, each conduit 10 can be sealed to an exit point of the manifold 9. A common conduit 10 can be used to connect an exit of the manifold 9 to all core material nozzles 5. Alternatively, a plurality of conduits 10 can be used to connect a corresponding plurality of manifold exits to the core material nozzles 5. For example, one manifold exit and conduit 10 may be provided for each core material nozzle 5. This is shown in figure 1.

Alternatively, the core material 2 may flow into the core material nozzles 5 directly from the reservoir 9. For example, the upper support plate 7 may comprise the floor of the core material reservoir 9 so that the entrances of the core material nozzles 5 are open to the main body of core material liquid 2 in the reservoir 9. In these circumstances, the upper support plate 7 may be moveable relative to the walls of the reservoir 9 so that it and the core material nozzles 5 can be vibrated without having to vibrate the rest of the reservoir 9. For example, a suitable seal can be provided at the join between the upper support plate 7 and the containing walls of the reservoir 9 so that there is no leakage of the core material 2 at the join. The flow of core material 2 between the reservoir 9 and the core material nozzles 5 may be aided by a pump (not shown) which is configured to pump the core liquid out of the reservoir 9 into the nozzles 5. If a pump is included in the apparatus 4, it can be used to pump the core material 2 into the core material nozzles 5 from a reservoir location which is above, level with or below the upper support plate 7. A valve (also not shown) can be used to control the flow rate of the core material 2 to and/or in the nozzles 5. The valve can be located, for example, in the conduit 10 or at the exit of the reservoir 9.

As shown in figure 1, the upper and lower supports 7, 8 are separated by a shell material feed region 11, which comprises a volume or void 11 which extends between the substantially parallel main surfaces of the plates 7, 8. The volume 11 may be defined by the surfaces of the plates, optionally together with upstanding walls at the edges of the supports 7, 8. The plates 7, 8 and walls are preferably impermeable to the shell material 3 so that the shell material is contained in the feed region 11. The shell material feed region 11 feeds shell material 3 to the entries of the shell material nozzles 6. In operation, liquid shell material 3 can flow into the region 11 between the upper and lower supports 7, 8 so that it can enter the shell liquid nozzles 6. For example, a shell material reservoir 12 may supply liquid shell material 3 into the region 11. Optionally, one or more pumps can be used to pump the liquid 3 into the region 11 and/or pressurize the liquid 3 in the region 11 so as to aid its passage through the shell material nozzles 6 in the lower plate 8.

As shown in figure 1, the shell material 3 may be fed into the region 11 in a direction which is substantially perpendicular to the directions in which the core material 2 is fed to the core material nozzles 5. For example, as shown in figure 1, the core material 2 can be fed to the core material nozzles 5 in a substantially downward, vertical direction and the shell material 3 can be fed into the feed region 11 and hence to the shell material nozzles 6 in a substantially horizontal direction. The feed direction of the shell material 3 may also be substantially perpendicular to the direction in which the core and shell material 2, 3 flow through their respective nozzles 5, 6. Apertures in the walls referred to above may be used to feed the shell material 6 into the feed region 11 in all horizontal directions. The substantially horizontal feed direction of the shell material 6 can be approximately parallel to the main plane of the upper and lower support plates 7, 8.

Referring to figure 3, the core liquid nozzles 5 and shell liquid nozzles 6 form pairs of nozzles, each comprising a single core liquid nozzle 5 and a single shell liquid nozzle 6. More specifically, each core material nozzle 5 extends downwardly from the upper support plate 7 across the void 11 between the plates 7, 8 and into one of the shell liquid nozzles 6 located in the lower plate 8 to form the nozzle pair 5, 6. Optionally, as shown in figure 3, the core and shell liquid nozzles 5, 6 of each nozzle pair are concentric with one another. The diameter of the entries and exits of the core nozzles 5 may be significantly smaller than those of the shell nozzles 6 so that shell liquid 3 can freely enter and exit the shell nozzles 6.

As may be evident from the discussion above, the location of each of the core material nozzles 5 with respect to other core material nozzles 5 may be fixed by its position in the upper support 7. Likewise, the location of each of the shell material nozzles 6 with respect to other shell material nozzles 6 may be fixed by its position in the lower support 8. However, the location of the core material nozzles 5 with respect to the shell material nozzles 6 may be altered by relative movement of the upper and lower supports 7, 8. The degree of relative movement may be relatively small, for example 5cm or less, but is sufficient for the groups of core and shell material nozzles 5, 6 to be independently vibrated. Therefore, each nozzle pair 5, 6 may comprise independently vibratable core and shell material nozzles 5, 6. The upper and lower supports 7, 8 and groups of core and shell material nozzles 5, 6 can be vibrated by one or more vibration units 13 during capsule formation. For example, one or both of the supports 7, 8 may be connected to a vibration unit 13 which is configured to vibrate the support(s) 7, 8 including the core and shell liquid nozzles 5, 6. The vibration unit 13 may, for example, comprise a cam 14 which is configured to apply the vibration to the support 7, 8 as it rotates. The cam 14 can be connected to the support(s) 7, 8 via a rod 15 which is fixed to a non-central point on the cam 14 so that the rod 15 pushes and pulls the support(s) 7, 8 so that the support(s) 7, 8 moves in a lateral, substantially horizontal plane as the cam 14 rotates. This is shown schematically in figure 1. It will be understood that other types of vibration unit 13 can alternatively be used to achieve the lateral vibration in the support 7, 8. Optionally, an individual vibration unit 13 is provided for each support 7, 8.

At the exit of the nozzle pairs 5, 6, the core material 2 being outputted from the core material nozzle 5 and the shell material 3 being outputted from the shell material nozzle 6 combine to form a combined droplet 16 comprising an inner region of core liquid 2 surrounded by an outer layer of shell liquid 3. The formation of the combined droplet 16 is caused by the relative positions and dimensions of the core and shell material nozzles 5, 6 and is aided when a vibration is applied to the nozzles 5, 6 by the vibration unit 13 referred to previously. Referring to figure 4, in a first stage SI of the capsule 1 formation process, a stream of core material 2 may flow substantially continuously from the reservoir 9 along the one or more conduits 10 into the core material nozzles 5. The flow of core material 2 is shown by arrows in figure 1. Likewise, simultaneously in a second process S2, shell material 3 may flow substantially continuously from the shell material reservoir 12 into the shell material feed region 11 and, from there, into the shell material nozzles 6.

As referred to above, an example of a pair of core material and shell material nozzles 5, 6 is shown in figure 3. The nozzles 5, 6 are concentric, with the core material nozzle 5 of each pair partially extending into the shell material nozzle 6. The core material nozzle 5 may have smaller entry and exit diameters than the shell material nozzle 6. The entrances of the shell material nozzles 6 are open to the common shell material feed region 11 so that liquid shell material 3 enters the shell material nozzles 6 from the feed region 11. The shell material 3 may be under pressure in the feed region 11 so that it is forced through the shell material nozzles 6 by a pressure differential between the entries and exits of the nozzles 6.

Additionally or alternatively, the shell material 3 may move through the shell material nozzles 6 under gravity.

The entrances of the core material nozzles 5 are open to the core material reservoir 9, for example either directly or via the conduit(s) 10 referred to above, so that core material 2 enters the core material nozzles 5 under gravity. The flow of liquid material 2, 3 through one or both of the sets of the core and shell material nozzles 5, 6 may optionally be aided by the action of one or more pumps configured to pump the liquid 2, 3 through the nozzle(s) 5, 6. The one or more pumps (not shown) are configured to provide extra motive force to aid with discharge of the core and/or shell material 2, 3 from the nozzle(s) 5, 6. The pump(s) may, therefore, be of particular help for discharging materials 2, 3 which have a relatively high viscosity. The extra motive force provided by the pump(s) may be regulated by opening and/ or closing one or more control valves. For example, the control valves can be selectively opened or closed to increase or decrease the flow rate of materials 2, 3 into/ out of the nozzles 5, 6. The control valves may be of particular help for materials 2, 3 which have a relatively low viscosity and for which the flow rate provided by the pump is undesirably high.

As referred to above, at the exit of each nozzle pair 5, 6, the core material 2 being outputted from the core material nozzle 5 and the shell material 3 being outputted from the shell material nozzle 6 combine to form a combined droplet 16 comprising an inner region of core liquid 2 surrounded by an outer layer of shell liquid 3.

The one or more vibration units 13 can be used to vibrate the nozzles 5, 6 as the core and shell liquids 2, 3 move through them. This may be effected by applying a lateral vibration to one or both of the supports 7, 8 so that the supports 7, 8 move back and forth in a substantially horizontal direction. Additionally or alternatively, the vibration unit 13 can be used to vibrate the conduit(s) 10 through which the core material 2 may flow to the core material nozzles 5. The vibration caused by the vibration unit 13 aids with breaking up the continuous stream of core and shell material 2, 3 into the droplets 16 at the nozzle exits. The frequency at which the vibration unit 13 applies a vibration is adjustable in response to user controls so that the application of the vibration can be optimized for the particular core material 2 and/ or shell material 3 being used and the desired droplet size. The supports 7, 8 can be vibrated independently at a different frequency to each other. In a third stage S3 of the process, combined droplets 16 which have exited the pair of nozzles 5, 6 can enter a fluid 17 such as a suitable oil in which the shell material 6 is caused to solidify. The fluid 17 may be a cooling fluid configured to solidify the shell material 3 by reducing its temperature, and will be described below in such context. However, it will be appreciated that alternative, for example chemical, solidification processes can take place to solidify the shell material 3 and therefore that the fluid 17 does not need to be a cooling fluid 17.

The fluid 17 is preferably immiscible or substantially immiscible with the shell material 3. It may comprise a suitable food-grade oil. Alternatives to oils include propylene glycol, glycerol, or other suitable food-grade material which, if used as a cooling fluid, remains in the liquid phase at temperatures below the freezing point of the shell material 3. The central core material 2 may remain liquid, for example due its freezing temperature being lower than the temperature of the fluid 17 or because it does not chemically react to cause hardening.

Optionally, droplets 16 exiting the nozzle pair 5, 6 can fall under gravity through a gas such as air into a fluid reservoir located below the exit of the nozzles 5, 6. Alternatively, as shown in figures 5 to 7, the exits of the nozzles 5, 6 may be immersed in the fluid 17 so that droplets 16 enter the fluid 17 directly from the nozzle pair 5, 6. In a fourth stage of the process S4, a flow pattern may be established in the fluid 17. For example, a re-circulating flow of fluid 17 may be established so that fluid 17 flows around a looped system which starts and finishes at the nozzle exits.

Other types of flow pattern are also possible, as discussed further below. Baffles may be used to aid with directing the fluid 17 around the loop. Additionally or alternatively, the flow of fluid 17 may be at least partially directed by the use of other fluid directors such as angled nozzle jets, pumps and/or paddles which are configured to eject or direct streams of the fluid 17 into the larger flow, or main body, of fluid 17 at a higher velocity than the larger flow, or main body, of fluid 17. The fluid 17 carries the droplets 16 away from the nozzle exits to a collection point. If a flow pattern is used, one or more flow restrictors may be placed in the path of the fluid 17 in order to regulate its flow. This is shown in figures 5 and 6.

If a flow pattern is used, the flow of fluid 17 carries the capsules 1 /droplets 16 to a collector 18, for example a suitably sized mesh or grating immersed in the stream of fluid 17, which collects the capsules 1 whilst allowing the fluid 17 to pass through it. The collector 18 may be angled to allow for the capsules 1 to roll down a slope into a receptacle 18a, whilst separating the fluid 17 and allowing it to re-circulate. As previously described, the fluid 17 may subsequently be driven around a looped system back to the nozzles 5, 6, from where it carries more droplets 16/capsules 1 to the collector 18 in the manner described above. This is discussed in more detail below with respect to fluid flow patterns, particularly in relation to figure 7. The looped system can optionally incorporate a refrigeration unit 19 which is configured to cool the fluid 17 as it re-circulates back to the nozzles 5, 6.

As referred to previously, the combined droplets 16 of core and shell material 2, 3 exiting the nozzle pairs 5, 6 take on a substantially spherical shape in the fluid 17. Therefore, as the outer layer of shell material 3 solidifies in the fluid 17 during a fifth step S5 of the process, it forms a substantially spherical shell 3 around the internal core material 2. In its simplest form, the flow pattern may comprise a longitudinal and substantially uniform stream of fluid 17 which flows past the exit points of the nozzles 5, 6 at a substantially uniform velocity and carries the droplets 16 to the collector 18 along a relatively short and direct longitudinal path. An example is shown in figure 5.

A more sophisticated flow pattern comprises driving the droplets 16 along a spiral path in the fluid 17, so that the droplets 16 travel to the collector 18 along a relatively long and indirect path. An example is shown in figures 6 and 7. This may be achieved by driving the fluid 17 itself in a spiral pattern, at least in a region between the nozzle exits and collector 18, by one or more fluid directors such as jets, paddles and/or pumps so as to cause the droplets 16 to follow a spiral path on their way to the collector 18. The pipe or shaft 20 along which the droplets 16 are driven may be shaped so as to aid with the creation and maintenance of the spiral flow pattern in the fluid 17. By driving the droplets 16 along a spiral path towards the collector 18 rather than the direct path described above and illustrated in figure 5, the droplets 16 spend more time and travel a further distance in the fluid 17 for a given longitudinal distance travelled towards the collector 18 (e.g. for a given length of pipe 20). Therefore, compared to the direct, longitudinal path referred to above and shown in figure 5, an equivalent hardening, for example cooling, time and distance of travel for the droplets 16 in the fluid 17 is obtained for a much shorter longitudinal distance between the nozzle exit and the collector 18. The number of droplets 16 present per unit volume of fluid 17 is also increased. As such, the size and, in particular, the footprint of an apparatus 4 using a spiral flow path can be much smaller than an apparatus 4 using a more direct flow path between the nozzle exit and collector 18. A high rate of capsule production can be attained with a small overall size of apparatus 4.

Referring to figure 7, the plurality of pairs of the nozzles 5, 6 may all be immersed in the same stream of re-circulating fluid 17. Thus, only a single fluid system is required to serve all nozzles 5, 6. The fluid system is common to all nozzles 5, 6.

By providing a common fluid system and/ or common core and shell material source tanks, the overall size, in particular the footprint, of the apparatus 4 is reduced compared to apparatuses which do not use such common fluid and/ or supply systems.

The fluid 17 may be driven in any of the flow patterns referred to above and re- circulates in a looped cycle to continuously carry droplets 16 emitted by the nozzles 5, 6 to the collector 18, hardening the shell material 3 and creating a capsule 1 on the way. A cooling unit 19 such as the refrigeration unit 19 referred to previously may be positioned within the loop so as to cool the fluid 17 as required during circulation. In figure 7, the fluid 17 is driven along a spiral path between the nozzle exits and the collector 18 thereby allowing the outer shell layer 3 of the droplets 16 to be hardened over a relatively short longitudinal distance between the nozzles 5, 6 and the collector 18. This configuration of looped system allows a reduction in the height of the apparatus 4 because the main flow of fluid 17 is in a horizontal rather than vertical direction.

Once the shell layer 3 has solidified, the shape of the body of core material 2 is defined by the shape of the solid shell 3. It is advantageous for the core material 2 to be in a liquid state for reasons that will be explained below. The capsules 1 are removed from the fluid 17 using the collector 18 described above.

A suitable shell material 3 can be a gelatine solution which gels to form a solid and frangible material. The shell material 3 is able to irreversibly change state from a liquid solution to a solid in the fluid 17. This state change can be driven, for example, by a change in the temperature of the shell material 3 in the fluid 17 or by a compound present in the fluid 17 which causes the shell material 3 to solidify. It will be appreciated that there are a variety of different gelling or encapsulating substances which could be used as the shell material 3 which, when treated, form a solid, frangible shell; for example, gelatin, sodium alginate and guar gum. The shell material 3 can be formulated to include a compound which will cause the shell material 3 to solidify once in contact with the fluid 17. For example, the reaction of calcium ions with sodium alginates may be used. The calcium ions and sodium alginates may be contained in opposite ones of the shell material 3 and fluid 17 so that the reaction occurs upon contact.

Solidification of the shell material 3 in the fluid 17 forms a solid coating 3 which wholly encapsulates the core material 2. The thickness of the shell 3 can be adjusted as required by increasing or reducing the amount of shell material 3 which is combined with each quantity of core material 2 at the nozzles 5, 6. The thickness of the shell 3 may impact the characteristics of the capsule 1. For example, the thickness of the shell 3 may affect how frangible the capsule 1 is.

The capsules 1 formed using the above-described process comprise a liquid, for example menthol, core 2 encapsulated by a solid, for example gelatinous, shell 3. The solid structure of the shell 3 has different physical and chemical properties compared to the liquid precursor from which it was formed. For example, once solidified around the cores 2, the solid shell 3 may be thermally stable in a temperature range of between -15 and 60 degrees Celsius. The shell 3 will also provide an impermeable barrier to the core material 2 inside the capsule 1. This prevents the core material 2 from leaking from the capsule 1, even when it is in a liquid state. The thickness and structure of the shell 3 is such that when the capsules 1 are squeezed between finger and thumb with a relatively modest amount of pressure, the shell coating 3 cracks or otherwise breaks so that the liquid core material 2 contained within the shell 3 is released. If the capsule 1 is inserted into a cellulose acetate filter of a cigarette in an optional sixth step S6, breaking the capsule causes liquid core material 2 to bleed into the fibrous filter material and thus add flavour to smoke as it is drawn through the filter from the tobacco rod.

The embodiments and alternatives described above can be used either singly or in combination to achieve the effects of the invention.

Claims

1. A capsule forming apparatus comprising:

a first support in which a plurality of first outputs configured to output a first capsule material are located;

a second support in which a plurality of second outputs configured to output a second capsule material are located; and

a second capsule material feed region between the first and second supports from which the second capsule material can enter the second outputs.

2. A capsule forming apparatus according to claim 1 , wherein the second capsule material feed region comprises a gap between the first and second supports.

3. A capsule forming apparatus according to claim 1 or 2, wherein each of the first outputs comprises a first nozzle and each of the second outputs comprises a second nozzle.

4. A capsule forming apparatus according to any preceding claim, wherein each first output extends at least partially into one of the second outputs to form a pair of outputs.

5. A capsule forming apparatus according to any preceding claim, wherein the first support is substantially parallel to the second support.

6. A capsule forming apparatus according to any preceding claim, wherein the first support comprises a first substantially elongate member through which the first outputs extend and the second support comprises a second substantially elongate member through which the second outputs extend.

7. A capsule forming apparatus according to any preceding claim, wherein the first support comprises an upper plate which connects all of the first outputs together and the second support comprises a lower plate which connects all of the second outputs together.

8. A capsule forming apparatus according to any preceding claim, wherein boundaries of the shell material feed region are impermeable to the shell material.

9. A capsule forming apparatus according to claim 8, wherein the boundaries of the shell material feed region comprise surfaces of the supports.

10. A capsule forming apparatus according to any preceding claim, wherein the apparatus is configured to feed the first capsule material to the first outputs in a substantially downward, vertical direction and wherein the apparatus is configured to feed the second capsule material to the second outputs in a substantially horizontal direction.

11. A capsule forming apparatus according to any preceding claim, wherein the apparatus is configured to feed the first capsule material to the first outputs in a direction substantially parallel to a principal output direction of the first outputs and wherein the apparatus is configured to feed the second capsule material to the second outputs in a direction substantially perpendicular to a principal output direction of the second outputs.

12. A capsule forming apparatus according to any preceding claim, wherein the capsule materials output by the outputs comprise droplets having an inner core of the first capsule material and an outer shell layer of the second capsule material.

13. A capsule forming apparatus according to any preceding claim, wherein the first capsule material comprises a capsule core material and the second capsule material comprises a capsule shell material.

14. A capsule forming apparatus according to any preceding claim, comprising a vibration unit configured to vibrate a plurality of the first outputs or a plurality of the second outputs or both.

15. A capsule forming apparatus according to any preceding claim, further comprising a body of fluid into which the outputs are configured to output the capsule materials, the fluid being configured to harden the second capsule material.

16. A capsule forming apparatus according to claim 15, comprising a fluid director configured to cause the capsule materials to follow a spiral path in the fluid.

17. A capsule forming apparatus according to claim 15 or 16, wherein the apparatus comprises a looped system around which the fluid is driven to and from the outputs.

18. A capsule forming apparatus according to claim 15, 16 or 17, further comprising a cooling unit configured to cool the fluid to a temperature sufficiently low to solidify at least one of the capsule materials.

19. A capsule forming apparatus comprising:

a capsule material output configured to output capsule material into a body of fluid; and

a fluid flow director configured to create a flow of fluid which causes outputted capsule material to follow a spiral path in the body of fluid.

20. A capsule forming apparatus according to claim 19, wherein the fluid is configured to harden the capsule material.

21. A method of forming capsules comprising:

supplying a first capsule material to a plurality of first outputs located in a first support;

supplying a second capsule material to a plurality of second outputs located in a second support, comprising supplying the second capsule material via a second capsule material feed region located between the first and second supports;

outputting a droplet comprising the first capsule material and the second capsule material from a combination of the first and second outputs.

22. A method according to claim 21, wherein the droplet comprises a liquid core of the first capsule material surrounded by a liquid layer of the second capsule material, and the method further comprises hardening the second capsule material to form a shell around the liquid core.

23. A capsule formed according to the method defined in claim 21 or 22.