This invention relates to systems for dispensing substances from containers and, more particularly, to such systems employing a very simple but effective two phase solid/gas adsorption/desorption mode of operation.

A large number of products are on the general market packaged in canisters - some of which cause the product to be dispensed therefrom in the form of small or atomised particles and are therefore commonly referred to as

'aerosols' - and which can be dispensed from the canister by means of a gas (or vapour) pressure generated in situ in the canister, ie acting as a dispensing or propellant gas. Such products include ones for personal care including hair sprays, shaving creams, deodorants and the like and ones for household use including cleaning substances, room fragrances, insect repellents and the like, and many more.

In some cases, such products are admixed with the pressurised gas in the canister and the operation of a (typically) push-down operating valve causes both the product and the gas to be dispensed from the pack by means of the gas pressure via a 'dip tube' extending in to the product and linked to a nozzle which is commonly associated with the release valve, all of which are commonly contained in a dispense assembly or dispense block.

In other cases, the product and pressurised gas are separated from each other within the canister. Typically, some form of divider or membrane is present in the canister, for example, one in the form of a bag containing the product to be dispensed which is sealingly held to the canister internal wall in the vicinity of the release valve; the gas is present between the divider and the internal walls of the pack, ie surrounding the bag and the gas pressure in turn exerts pressure on the product in the bag. Alternatively, the divider may be a piston which slides within the canister with the product on one side and a gas on the other side and which acts to drive the product from the canister by the action of gas pressure. Whichever type of pressure pack is adopted will depend on the nature of the product and the use to which it is to be put and on the nature and properties of the propellant gas, in particular whether the propellant gas might react with the product or whether, for example, it might be flammable or odorise the product. The use of chlorofluorocarbons (CFCs) previously became very popular as propellant gases for such product dispense canisters in that they can be readily condensed and vaporised in a reversible manner responsive to the surrounding pressure. This was followed by the use of hydrofluorocarbons (HFCs) and also hydrochloroflurocarbons (HCFCs) which were regarded as being somewhat more environmentally friendly.

However, more recently, such propellant gases have in general been phased out owing to their acknowledged environmentally harmful properties, in particular ozone depletion of the upper atmosphere.

Alternative propellant gases which have been commonly used are certain hydrocarbon gases including liquid petroleum gases (LPGs) such as propane and butane. Such gases, however, are by their nature extremely flammable, are environmentally harmful in some respects and in addition can introduce an odour in to the product being dispensed.

It is known that numerous attempts have been made to replace LPG propellant gases with gases such as air, nitrogen, carbon dioxide and the like. These attempts have largely been effected simply by utilising a pressurised gas within the canister;

in practice, the canister valve is depressed to propel the product from the canister in the general manner described above. However such attempts have been largely unsuccessful due to the large pressure changes in the canister during use, commonly leading to reduced dispense characteristics at low pressures and a loss of pressure before full product dispense which results in a slow dispense of the last product from the canister.

It is known that efforts to develop such prior systems were based primarily on the preferred embodiments described in these European applications, namely the use of a gas/liquid/solid system in which carbon dioxide as the gas was dissolved in acetone as the liquid which itself occupied voids in a solid.

.It was also disclosed in our Specification WO 2005/070788 that the use of a new system not involving polymeric materials and not involving troublesome liquids or displacing agents and being more suitable for commercially viable assembly in to the aerosol canister can provide an efficient sorption/desorption propellant system for product dispense.

In accordance with the disclosures of this prior application, a dispensing system for dispensing a product from a canister is provided which comprises a solid/gas arrangement in which the gas is adsorbed on to the solid under pressure and desorbed therefrom when the pressure is released and in which the solid comprises activated carbon and the gas comprises one or more of nitrogen, oxygen (or mixtures thereof including air), carbon dioxide, nitrous oxide and argon, the container having valve means to allow the gas adsorbed on to the carbon to be desorbed and effect product dispense.

The gas is preferably carbon dioxide in view of its generally superior adsorption characteristics in relation to activated carbon as an adsorbent.

The term 'adsorbed gas' used herein refers to the gas used in the invention. It was found that such a system, despite its simplicity, can provide the basis for an efficient, safe, reliable and reproducible system for product dispense.

It was found in particular that the new dispense system can provide - by means of careful selection of the type of activated carbon employed, the amount of carbon, the initial pressure and therefore the amount of gas adsorbed on the carbon - a low pressure change during intermittent use between an initial product dispense and full product dispense from a canister. The pressure change afforded by that invention between a 'full' and 'empty' canister is such that the canister in which it is positioned can maintain an effective discharge of product with an effective and acceptable controlled spray pattern in terms in particular of its being uniform and/or homogeneous with a predetermined particle size and distribution.

Systems of that invention have been shown to be particularly suited to the dispensing of products from small, hand-held 'aerosol' canisters, for example ones having a 200 or 300ml capacity. The term 'aerosol' when used herein includes any hand-held dispensing devices for the delivery of product whether or not the product is actually atomised or whether or not it incurs any other form of product break-up.

In accordance with the prior disclosures, the dispensing system preferably incorporated in to a canister in which a product to be dispensed is held under gas pressure. In such embodiments, carbon dioxide desorbed from the carbon adsorbent pressurises the canister and maintains the pressure therein generally and during actuation of the canister dispensing valve in particular.

Preferably, the product and the solid/gas arrangement are present in separate compartments in the canister. This is primarily to keep the product and the solid apart from each other in order to hold the solid in a predetermined part of the canister and/or to ensure in particular that the product, which may for example P2013/002585

5 be in aqueous or other type of solution, does not contaminate the solid and thereby detract from its efficiency of adsorption.

In some instances, the compartments may be separated by means of a wholly or substantially impermeable membrane. This membrane may take the form of a flexible bag which is sealingly attached either to the interior wall of the canister, the canister aperture or to the canister operating valve (or dispense block incorporating the valve), and which in use holds the product to be dispensed. The solid/gas arrangement is generally positioned within the canister but outside the bag such that pressure is exerted on the exterior of the bag; on actuation of the valve, this pressure causes product dispense to be effected via the valve block through an associated nozzle. An elastic or non- elastic material may be employed to form the bag. Furthermore, the membrane, whether of elastic or non-elastic material may be used and may be sealingly attached to any relevant part of the canister interior.

One specific embodiment of this is for the bag to be sandwiched, and sealed, between the canister aperture and the release valve; this is commonly referred to as a 'bag-in-can' arrangement.

Another specific embodiment of this is for the bag to be sealed on to the release valve and for the release block then to be sealed within the canister aperture; this is commonly referred to as a 'bag-on-valve' arrangement.

The substantially impermeable membrane may alternatively take the form of a piston slideably mounted in the canister interior with the gas/solid arrangement on one side of the piston and the product to be dispensed on the other side such that actuation

of a dispense valve causes pressure from gas desorbed from the solid to move the piston and urge product to be dispensed from the canister via the valve. In other instances, the compartments may be separated by means of a fixed partition. Such a fixed partition may usefully be positioned in the any useful part of the canister, and preferably including the base thereof, to form the solid/gas arrangement compartment therein. It can, for example, be a concave-shaped disc in a 'flat' canister base or one of greater concavity than the (usually) concave-shaped canister base (as viewed from the exterior of the canister). It may advantageously be crimped to the canister between the canister wall(s) and its base to form an annular compartment between the disc and the base. The solid compartment may also be in the form of a container or 'widget' that may be fixed to the canister (or part thereof) or allowed to be free within the canister interior which, on use of the canister, allows the pressurised gas to be released therefrom. . In addition, the carbon container may be associated with the canister dip tube, for example by being mounted around the dip tube for ease of assembly of the canister generally and the positioning of the container therein and, separately to allow for a ready filling of the container with adsorbed gas via the dip tube and via a one-way valve therebetween.

Generally, the product and the solid/gas arrangement of the dispensing system are present in individual compartments in the canister, which are separated by a partition which may be fixed or displaceable. This keeps the product and the solid apart from each other in order to hold the solid in a predetermined part of the canister and/or to ensure in particular that the product, which may for example be in aqueous or other type of solution, does not contaminate the solid and thereby detract from its efficiency of adsorption.

With a fixed partition, for example the substantially rigid wall of the carbon container, it is generally required that the gas from the solid/gas compartment can flow in to the product compartment, but not vice versa, and this can readily be effected by having a one-way valve in the partition. Equally, there was a general need to provide means to allow the introduction of carbon dioxide in to the solid/gas compartment prior to use of and during use of the system; this can also be effected by a one-way valve to prevent back flow of the gas from the solid/gas compartment. Each one-way valve should be designed such that is operates only under a certain applied pressure, for example a small fraction of 1 bar; otherwise the valve does not open.

With certain designs of valve, it is possible for a single valve to operate separately as a pressure thereof sensitive valve in either direction depending on the requirements of the system.

In such embodiments, the container for the carbon should have one-way valve means in order to allow the carbon dioxide to be desorbed from the solid and pass in to the product compartment when the pressure in the canister falls, ie on operation of the canister dispensing valve, and thereby maintain canister pressures at predetermined levels for further use of the aerosol.

The one-way valve advantageously is formed integrally with the partition and is preferably made from a plastic material, for example PET or silicone rubber.

With a displaceable partition, this will generally be impermeable to the gas and may take the form, for example, of a bag for holding the product or a piston slideable within the canister with the desorbed gas from the carbon deforming the bag or moving the piston within the canister under the increased gas pressure applied thereon during actuation of the dispensing valve.

In all embodiments, the carbon is advantageously held in a container which is preferably proximate to the dispensing block, for example by being attached thereto or may be less firmly linked, for example via a tube through which the carbon dioxide can be introduced in to the container. In such preferred embodiments, the dispensing block itself advantageously incorporates a canister dispensing valve and passageways linking the interior of the canister with the exterior thereof via the valve. As such, the dispensing block, together with the carbon container, can readily and effectively be sealingly inserted in to an aperture in the canister during canister assembly.

In particular, the linkage of the container to the dispensing block generally allows firstly for a ready operation of the pressure pack and secondly allows for a simple mode of manufacture and assembly of the aerosol canister by allowing for the dispensing block - incorporating the canister dispensing valve, necessary passageways linking the interior of the canister with the exterior thereof, and also the carbon container linked thereto - to be inserted in to an aperture in the canister, ideally the top of the canister, advantageously in a single assembly step.

The invention therefore allows standard designs of canister to be employed without modification to the body thereof in order to suit implementation of the invention generally and to include canisters made of either steel or aluminium or other material.

The product to be dispensed by the system of the invention is commonly inserted in to the canister via a dip tube depending from the dispensing block and through which, in use of the aerosol, the product is dispensed via the dispensing valve in the reverse direction. The solid/gas container is

advantageously linked to the dispensing block, for example by being positioned co-axially about the dip tube and as such can be regarded as an integral part of the dispensing block. In such cases, the block as a whole can therefore readily be placed in a canister aperture simultaneously during canister assembly. Means must also be provided for the introduction of the gas under pressure in to the carbon container in order to cause it to be adsorbed on to the carbon and subsequently desorbed therefrom on operation of the dispensing valve. This can be effected, for example, by providing a suitable route via the dispensing block in to the container interior and including (as described above) a one-way valve to prevent back flow of the gas. Overall, therefore, the product dispensing system provides a simple and effective way of utilising gas desorbed from the adsorbent jDer se in order to provide a sufficient gas volume to produce an initial gas pressure and thereafter to maintain gas volumes, and necessary gas pressures, to enable a complete product dispense to be effected.

With regard to the gas, it should be introduced in to the dispensing system under pressure and which will be adsorbed on to the carbon such that its molecules are much more closely packed together than in the usual gaseous form at the same temperature and pressure. This means that, when the gas is introduced under pressure in to a "gas space" surrounding the carbon, considerably more gas will be adsorbed on to the carbon. Consequently, as the system is activated, typically by actuating the pressure release valve, there will in practice be only a relative and surprisingly small pressure reduction within the system which, in use of the system, therefore allows for the effective dispensing of all of the product.

In general, it is beneficial to charge the gas in to the container by means other than a 'bung hole' in the base of the canister as the presence of a bung hole may lead to gas leakage during storage/use of the canister.

Activated carbons are well known p_er se and have the advantage that they are relatively inexpensive; they are non-polymeric substances. In general, activated carbons are manufactured from a variety of carbonaceous materials including (1) animal material (blood, flesh, bones, etc), (2) plant materials such as wood, coconut shell, corn cobs, kelp, coffee beans, rice hulls and the like and (3) peat, coal, tars, petroleum residues and carbon black. P2013/002585

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Activation of the raw carbonaceous materials can be effected in a variety of known ways including calcining at high temperature (eg 500°C-700°C) in the absence of air/oxygen followed by activation with steam, carbon dioxide, potassium chloride or flue gas at, say, 850°C to 900°C, followed by cooling and packaging.

Selected activated carbons are suitable for use in the systems of the invention, for example ones having a density of from 0.2g/cm ³ to 0.55g/cm ³ , preferably 0.35g/cm ³ to 0.55g/cm ³ .

The quantity of carbon required in implementing the invention will vary depending on parameters including the gas employed, the initial and final pressures during the dispense of product, the nature of the product and its physical characteristics and the desired properties of the dispensed product.

In the case of a standard size (300ml) canister, it is preferred for many product types to have a carbon content of from 5 to 30% of carbon (by volume) which generally equates, for selected carbons, to the presence of 10 to 60ml of carbon, more preferably 30 to 50ml of carbon, for example 40ml of carbon.

With other product types, especially those of relatively high concentration of active ingredient(s), the carbon content may usefully be from 30 to 95%, preferably from 60 to 90%. Such improvements are especially useful with more concentrated and/or more viscous products which might otherwise be difficult to disperse adequately for effective spray pattern or whatever.

In general, specific ways of treating and/or handling the carbon are important aspects of the invention and may be essential for the implementation of the dispensing systems. 5

11

In particular, it has been found that there may be a propensity for the required properties of the carbon to degrade after the carbon activation process. Such degradation may include adsorption sites on the carbon being blocked by a gas or gases present in the atmosphere present around the carbon and which cannot subsequently be displaced by the gas that is to be adsorbed as the working gas in the dispensing systems of the invention. Although the blocking process may be reversible in certain cases, displacement by the preferred gas may not be effected completely and therefore would detract from the

subsequent adsorption of the gas. In some instances, desorption of the initially held gas may be aided by high temperature and/or vacuum.

Preferably, therefore, the activated carbon is held, advantageously from the time of its production (to include a later production step or later recycle process), under a blanketing atmosphere; this atmosphere may comprise the adsorbed gas itself, or a gas or gases (including mixtures with the adsorbed gas) that do not prevent the adsorbed gas subsequently occupying the carbon adsorption sites, in particular by virtue of being held at the adsorption sites on the carbon less strongly than the adsorbed gas. Certain gases, including water vapour, are more strongly held at the carbon adsorption sites than the adsorbed gas and carbon dioxide in particular and therefore should be rigorously excluded from the atmosphere around the carbon; subsequent attempts to dislodge the strongly held gases will not be successful.

Although some gases are less strongly held at the adsorption sites than carbon dioxide and other adsorbed gases, they may still interfere with the subsequent adsorption efficiency characteristics of the adsorbed gas and should be avoided as blanketing gases.

In the case of carbon dioxide as the adsorbed gas, the blanketing atmosphere preferably includes or comprises carbon dioxide itself. This can be especially advantageous in the implementation of dispensing systems when the carbon dioxide is preferably adsorbed on to the carbon at elevated temperatures. Other suitable gases include helium and hydrogen which are generally capable of being displaced from the adsorption sites by carbon dioxide. The potential use of other blanketing gases can be established by a skilled adsorption scientist on a theoretical or practical basis.

Adsorption is an exothermic process in which considerable amounts of heat may be generated. The adoption of these preferred embodiments with a blanketing atmosphere that includes carbon dioxide itself is beneficial in that it allows an initial level of adsorption of carbon dioxide to occur - together with a dissipation of the generated heat - prior to the use of the carbon in the dispensing systems. This can lead to significant advantages from the resultant lower amounts of heat generated when the remaining carbon dioxide is adsorbed under pressure in subsequent high speed production of canisters incorporating the dispensing systems .

With all adsorbed gases, the blanketing of the carbon is preferably effected from the last production step, for example the time of cooling, and is preferably maintained continuously up to the time of (final) assembly of the canisters (or relevant individual canister components including pressurised widgets) in which the dispensing systems are employed. To achieve this, the use of containers for holding the blanketed carbon is required in order to isolate the carbon from undesirable gases.

In any event, the carbon granules or pellets or torroids may advantageously be pre-saturated with carbon dioxide (or other adsorbed gas) prior to use in order to improve the adsorption parameters. The granules/pellets/torroids may be advantageously cooled in such pre-saturisation processes by use of cooled carbon dioxide, for example carbon dioxide solid or snow being in contact with the carbon. Preferably, the carbon granules/pellets/torroids are usefully kept in contact with a source of carbon dioxide or other adsorbed gas, especially cold gas, liquid or snow, prior to placement in a canister and this may provide sufficient adsorbed gas for use in the system without the need to add further amounts of gas.

In the case of certain products, it has been found that it may be useful for optimum dispense characteristics to pre-treat the product with adsorbed gas prior to, or during, its introduction in to the canister. This can be especially useful in the case of highly soluble gases such as carbon dioxide, ie 'pre- carbonation'. Such a process is more useful in the case of product to be admixed with the adsorbed gas in the canister; it may, however, also apply to product present in the canister separated from the adsorbed gas by a moveable partition including a bag whether or not the partition allows for a certain leakage of gas therethrough.

Whatever embodiments of the product dispensing systems are utilised, there is a need to make them accord with existing commercial canister production/filling techniques and apparatus in order to allow them readily to be introduced in to, and be accepted by, the aerosol industry. Problems might arise, for example, in relation to complexity of apparatus, reduced canister filling and overall aerosol production speeds and associated increased costs, if such accord is not achievable.

As stated above, the adsorbent is advantageously blanketed with blanketing gas from the time of its final manufacturing (or recycling) step until its use in a sealed canister (or sealed component such as a pressurised widget).

Another issue relating to carbon integrity concerns the potential need to neutralise or render harmless any substances that might have a detrimental effect on the adsorption/desorption characteristics of the carbon in the event, for example of such substances permeating through a product bag and in to the area where the carbon is held. A main potential detrimental substance, as stated above, is water or water vapour. Other detrimental substances may be an alcohol or a liquid

hydrocarbon, or mixtures thereof or with other substances including water.

Whether or not a blanketing atmosphere is present to protect the carbon or other means are employed for that purpose, it has been found that a

scavenging agent for any water (or aqueous mixtures) that might come in to contact with the carbon may be useful in maintaining the necessary

adsorption/desorption characteristics of the carbon.

It has been found that in one particular area, namely the potential for water vapour to permeate from a water-containing or water-based product through or around a product bag held within the canister during use and/or storage of the canister and in to that part of the canister interior in which the adsorbent is held, the use of a desiccant is surprisingly beneficial. For example, the material from which the product bag is made may be (or in use become) somewhat permeable to water; alternatively, the manner in which the bag is attached to the canister body or to a valve block present in the canister aperture may degrade and again become susceptible to permeation of water. Equally, the bag may be ruptured in situ in the canister by a variety of means and thereby allow an escape of product from the bag.

Suitable water scavenging agents, or desiccants, include silica gel, certain types of zeolyte, for example Type X or Type Y, calcium chloride, calcium oxide and alumina.

Scavenging agents for other substances will be apparent to the skilled chemist.

The scavenging agents are usefully held in the canister adjacent to, or admixed with, the carbon particles. The scavenging agents are preferably present in an amount of 0.1 to 10% by volume of the carbon adsorbent, more preferably from 1 to 5%.

The exact sequence of the chemical reaction(s) is not fully understood but involves the formation of calcium hydroxide initially via the reaction of the calcium oxide with the water which subsequently reacts with the carbon dioxide present in the canister (including that released from the adsorbent) to form calcium carbonate. There are various issues to be addressed in the manufacture of aerosol cans incorporating these dispensing systems including:

- the provision of the adsorbent in its required form in the canister; - the ability to fill the canister with the gas and also with product to be dispensed as quickly as possible, ie at or as close as possible to commercial canister filling speeds.

The above systems are advantageously used in canisters having an internal bag for holding the product to be dispensed with the gas being outside the bag such that pressurised gas impinging on the bag exterior causes dispense of the product on actuation of the canister opening valve.

Ideally, the internal bag is one that is attached to a canister closure component incorporating the valve (a 'bag-on-valve'). Such components are usually supplied with the (empty) bag helically wrapped under the canister closure and securely (gas-tightly) attached thereto; advantageously, the bag is fixed to a dip-tube depending from the valve such that its interior is linked directly to the valve opening.

In a typical canister production process, each canister is advantageously pressurised with an 'under-the-cap' gassing procedure in which the gas is quickly supplied to the canister interior prior to sealing with the canister closure component with the bag positioned internally in the canister.

Certain problems may arise in the provision of canisters in accordance with the above disclosures. These include the possible practical difficulties encountered by aerosol canister manufacturers in the handling of activated carbons, especially if it is required to maintain them in a blanketing atmosphere during storage and subsequent canister production, and the accurate dosing of the carbon adsorbent in to each canister.

The improvements in the invention are concerned with means to overcome such difficulties.

In accordance with improved embodiments of the invention, a dispensing system for dispensing a product from a canister is provided which comprises a solid/gas arrangement in which the gas is adsorbed on to the solid under pressure and desorbed therefrom when the pressure is released and in which the solid comprises activated carbon and the gas comprises one or more of nitrogen, oxygen (or mixtures thereof including air), carbon dioxide, nitrous oxide and argon, the canister having valve means to allow the gas adsorbed on to the carbon to be desorbed and effect product dispense, wherein the activated carbon is designed to be incorporated in to the container conjoined with one or more of the canister components and wherein means are provided during canister production to cause the activated carbon to be put in to contact with the gas within the canister.

The conjoining of the carbon with such a component afford the possibility of simpler canister manufacturing /assembly processes, generally without the need for direct handling of the adsorbent before and/or during such processes. It is preferred for the components with which the carbon is conjoined to be supplied to the canister manufacturer/assembler as separate components for use by the manufacturer/assembler in the same manner as standard

components.

In preferred aspects of the invention, the carbon adsorbent may be conjoined simply by placing it in the folds of a wrapped bag-on-valve component and supplied in that simple form.

The carbon can advantageously be contained in a separate, sealed bag and conjoined with the product bag by being held in the folds as above or otherwise attached to the product bag or having both bags formed integrally with each other, advantageously with the carbon present in an integrally formed outer bag. This allows the carbon to be held in the assembled canister between the gas and the product in the integrally formed inner bag. Means are provided to allow the activated carbon to be put in to contact with the gas within the canister interior during canister production or at the time of actuation of the canister. As such, the carbon adsorbent should generally be designed to be released and/or exposed to the sealed canister interior, and thereby being brought in to contact with propellant gas sealed in the canister.

The term 'canister production' as used herein encompasses not only initial assembly of individual components such as valve block and canister casings but also gassing procedures and product introduction whether effected simultaneously, in sequence or over time generally.

In preferred embodiments of the invention, the means to allow the activated carbon to be put in to contact with the gas is actuated automatically in the canister production. This may be effected by having the carbon contained in a bag with a weak portion that breaks during a production step, for example when a carbon bag with a weakened portion is held within the folds of a product bag- on-valve and a product filling step causing the weakened portion to yield and release the carbon in to contact with the gas. P T/EP2013/002585

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A similar arrangement can be put in to effect wherein gas pressure alone may break a carbon bag. In the preferred case of a bagged product, the release/exposure to the gas is advantageously effected when the product is (or has been) inserted in to the product bag via, for example, the canister valve. This may be achieved in any suitable manner including the un-wrapping of bag folds, breakage of weakened areas of a bag, etc, during increased bag pressure with product fill therein.

Overall, the conjoined component may be supplied to canister manufacturers in exactly the same manner as existing designs of components with their use being made much simpler for the canister industry. In preferred embodiments, the carbon adsorbent is held under a blanketing atmosphere until being brought in to contact with the propellant gas in accordance with the invention. In such cases, the carbon may be sealed in a blanketed state in a carbon bag (or whatever) and conjoined with a canister component for use in the invention.

For a better understanding of the invention, reference will now be made, by way of exemplification only, to the accompanying drawing in which the Figure shows a schematic representation of an aerosol canister of the invention through the canister main axis.

There is shown in the Figure a hollow cylindrical canister body 1 with a wall portion 2, a circular, domed top portion 3 and a circular, domed bottom portion 4 (both as shown) that are both sealingly attached to the wall portion by means of crimps 5,6 around their circular edges. The body portions are made of metal, for example aluminium, but may also be made of other suitable materials. An aperture 7 positioned centrally in the top portion 3 is adapted to receive a metal valve block 8 in the interior of which is positioned a valve 9 operated by means of an actuator 10 and associated actuator cap 11. Depending from the valve block 8 is a bag-on-valve arrangement generally indicted by the reference numeral 12. This arrangement comprises a plastic tube 13 sealingly fitted in to the base of the valve block 8 and communicating with the interior of the block 8. A bag 14 is provided that is sealingly fitted around the tube 13 in the shaded area 14' at the top (as shown) therof, such that the interior of the bag 14 is also in communication with the interior of the block 8.

As shown in the figure, the bag 14 is present in the canister in the form that is wrapped around the tube 13 and held in its 'wrapped' form by breakable strips 15,16. In its expanded form, the strips 15,16 are broken and the bag 14 takes the shape shown by the line of reference numeral 17 whilst its interior remains sealingly connected to the tube 13 at 14' and thereby still in communication with the interior of the valve block 8.

A bag 18 is present in the form of a supplementary portion of the bag 14 - shown with the bag 14 in its expanded form by the reference numeral 17. This bag 18 is designed to be integrally formed with the bag 14, or fixed thereto or even simply held in position in the wrapped form by means of, for example, the effect of the strips 15,16.

In all cases, such a bag should be designed sealingly to hold the carbon and prevent ingress of any external gases/vapours and, if necessary, retain and maintain the interior atmosphere of the bag. Weakened portions or similar mechanisms should be incorporated in to the bag 18 to allow, on breakage of those portions, contact between carbon contained therein and propellant gas at the selected time. In the assembly/production of the aerosol canister 1 , the canister body 1 is generally available at the start of the production line.

In accordance with the invention, a bag-on-valve arrangement 12 is introduced on to the production line in a wrapped form as described above such that, in that form, it may be inserted readily through the aperture 7 in the canister top portion 3.

The bag-on-valve arrangement 12 is adapted to have the carbon, for example from 10 to 20g, sealingly contained in the 18 and thereby allow the carbon to be incorporated in to the canister conjoined with a canister component, namely the bag-on-valve arrangement, during canister production.

In the canister assembly/production, the bag-on-valve arrangement is inserted through the aperture 7 and loosely held therein during a gas filling operation in which gas is fed through the aperture around the loosely positioned valve block 8. The gas filling is ideally effected quickly, for example in about 1 second, and the valve block 8 is then substantially immediately fitted tightly in the aperture 7 and sealed therein by means of crimps/gaskets (not shown). As such, the carbon has been introduced in to the canister 1 conjoined with the bag-on-valve arrangement 12 and held therein in a sealed condition without the need to manage or monitor its condition.

The bag 14 remains in its wrapped form with the carbon not in contact with the propellant gas present in the canister 1 surrounding the bag 14 exterior. The bag 14 is designed to be filled with product to be dispensed, in use, from the canister 1. The filling is effected after the gas filling step above, or subsequently. The product is introduced in to the bag14 via passageways in the actuator 10 and the tube 13 and hence in to the interior of the bag 14.

The product fill will automatically expand the bag 14, breaking the holding strips 15,16, in to the position indicated by the reference numeral 17.

The bag expansion will also allow the carbon bag 18 to be 'exposed' and cause weakened portions thereof to fracture, thereby effecting contact between the carbon and the gas in the canister interior.

The fracturing of the carbon bag may be effected in different ways, for example by designing weak portions thereof to be broken by pressure change in the vicinity of the carbon bag 18, or simply by the movement of the carbon bag 18 and/or the product bag 14, as the bag 14 moves from its wrapped form to its expanded form.

Once fully assembled, an actuator cap 11 is placed over the actuator 10, depression of which in use of the aerosol canister will cause the actuator to operate the valve 8 and cause product 'P' to flow - as shown by the dotted line - from the bag 14 interior, up the tube 13 and through a nozzle 19 in the actuator cap 11 , all by means of the pressure exerted by the gas in the canister interior on the bag 14/17.