Field of the Invention

The present invention relates to aerosols with improved anti-corrosion properties and particularly, but not exclusively, aerosols for use in the field of domestic care products such as air fresheners, domestic cleaning products, fabric care, waxes, polishes, insecticides, ironing aids, fabric refreshers, carpet cleaners and the like as well as food products and personal care products.

Background

Many products designed for use in household applications such as on hard surfaces, for fabric care, as carpet cleaners are sold in aerosol containers. A few aerosol products are sold in glass or plastic containers. Most containers are metal canisters, most canisters are steel, usually tin coated, others are aluminium, but aluminium is expensive and not considered to be environmentally sustainable in comparison to the production of canisters made of other metals such as tin coated steel.

Tin coating protects the metal canisters against rapid corrosion, but tends itself to dissolve in aqueous based formulations. With aerosol formulations containing less than 50 ppm of water, corrosion of tin plated canisters is not generally a serious problem. However, if the water content of an aerosol product is more than 50 ppm (and particularly when greater than 150 ppm), problems due to corrosion are more likely to occur. Tin coated metal canisters may also be lacquered with a resin on the inside to provide additional corrosion protection but this adds expense to the manufacturing due to the need for additional raw materials and a greater processing complication as it is essential to ensure a suitably uniform application of resin.

The world market trend is to move towards water-based aerosol formulations. This is due mainly to a regulatory issue; the reductions of the volatile organic content (VOC) levels in aerosol products has involved the reduction of the solvent level in many products and an increase of the water content. Currently it is desirable to have a propellant level of below 30% w/w not only to reduce cost but also to comply with increasingly stringent regulatory limits.

Typically corrosion inhibitor systems are deployed in such canisters, especially for tin plated canisters. Examples of these products are borates, benzoates, molybdates, and anionic surfactants (such as sodium lauroyl sarcosinate). However, such corrosion inhibitor systems are notoriously difficult to work into the formulations to be deployed in the canister, are often expensive as raw materials and can, in some instances, be associated with undesirable effects to the formulation as the canister ages post-filling. A further problem with water and non-water based aerosol formulations is the availability of oxygen within the headspace of the canister, the greater the amount of oxygen that is available the greater the likelihood of corrosion within the canister due to oxidation thereof.

It is an object of the present invention to improve the known aerosol systems over those currently available.

Summary of Invention

According to a first aspect of the present invention there is provided therefore an aerosol comprising: a body; at least one valve having an inlet located within the body and an outlet located outside of the body defining a fluid pathway therethrough from the interior of the body to the exterior of the aerosol; a valve actuator engaged with the valve outlet; a dip tube in communication with the valve inlet; characterised in that the dip tube comprises oxygen scavenging material.

The deployment of oxygen scavenging material in and/or with and/or on the dip tube is considered to be particularly advantageous for several reasons. This oxygen scavenger will act to reduce the overall potential for corrosion inside the aerosol body. The oxygen scavenger will further assist in reducing the level of corrosion inhibitors required in the aerosol body. Furthermore, the oxygen scavenger may support a reduction in the amount of volatile hydrocarbon propellant required.

The further advantages of the deployment of oxygen scavenger material in/with/on the dip tube is that the life of the product can be extended due the reduced likelihood of corrosion-induced failure, this of course is particularly advantageous for food products such as aerosolised whipped cream as well as domestic care products which may only be exhausted after prolonged storage.

A yet further advantage of the deployment of oxygen scavenger material in/with/on the dip tube is that the potential reduction of corrosion inhibitors in the formulation permits a higher level of purity in the formulas to be sprayed, this may result in cleaner-smelling fragrances, more natural tasting food products etc.

Typically the dip tube is preferably made of a plastics material, such as polyolefins, and preferably the oxygen scavenging material is incorporated with the plastics material of the dip tube, such as by mixing the scavenger material as a masterbatch or additive in the the dip tube plastics material during the manufacture thereof. Alternatively or additionally, the dip tube has at least portion thereof coated with the oxygen scavenging material. Preferably substantially all of the dip tube surface is coated with said scavenger material. The coating may be applied by spray coating the dip tube with the scavenger material, possibly in combination with any required binders or adhesives. Both the exterior and interior surface of the dip tube may be coated with said scavenger material, but preferably only the exterior surface may be so coated. Alternatively the oxygen scavenging material may be made in sheet form and applied to the dip tube in any suitable manner.

The use of coating the dip tube and/or applying sheet form scavenger material may be beneficial if the dip tube is not made out of a plastics material or is made out of a plastics material which is not sufficiently compatible with the oxygen scavenger material to permit mixing in the masterbatch.

The quantity of oxygen scavenging material contained within each dip tube may be substantially 0.01-60% w/w of the dip tube, and preferably substantially 1-50% w/w of the dip tube, and more preferably substantially 10-40% w/w of the dip tube, and most preferably substantially 15-35% w/w of the dip tube.

Alternatively or additionally the dip tube may contain between 0.01 -30% w/v of oxygen scavenging material (i.e. 0.01-to-30g of scavenging material for each 100ml of oxygen in the aerosol to be scavenged), and preferably between 0.1-20% w/v of oxygen scavenging material, and more preferably between 0.5-15% w/v of oxygen scavenging material, and most preferably between 1-10% w/v of oxygen scavenging material.

Alternatively or additionally the dip tube may be provided with an amount of oxygen scavenging material in the dip tube that is appropriate to scavenge a quantity of oxygen within a container. In one embodiment the dip tube may be provided with sufficient oxygen scavenger material to scavenge between 0.01 -400% v/v of the aerosol body volume, and preferably between 1-200% v/v of the aerosol body volume, and preferably between 2-100% v/v of the aerosol body volume, and preferably between 5-50% v/v of the aerosol body volume.

The oxygen scavenging material that may be useful in the present invention may comprise at least one of the following: sulphates; oxidisable organic compounds; polymers and copolymers of alpha olefins; butylene copolymers; hydrogenated diene polymers; polyamides; substituted or unsubstituted ethylenically unsaturated hydrocarbon and copolymers thereof; polymeric compounds and other polymers prepared by olefin metathesis; diene oligomers; polymers or copolymers derived from dicyclopentadiene, norbornadiene, 5-ethylidene-2-norbornene, or other monomers containing more than one carbon-carbon double bond (conjugated or non- conjugated); carotenoids; condensation polymers; unsaturated fatty acids; and/or polymers or copolymers derived from (meth)allyl (meth)acrylates.

More specifically the oxygen scavenging material or materials that may be suitable in the present invention may include: oxidisible sulphates such as a sodium sulphate that can be oxidized to a sulphite; oxidisable organic compounds including: benzylic, allylic and/or tertiary hydrogen containing carbon compounds; polymers and copolymers of alpha olefins such as low density polyethylene, very low density polyethylene, and ultra low density polyethylene; polypropylene; polybutylene, i.e., poly(i-butene); propylene copolymers; butylene copolymers; hydrogenated diene polymers; polyamides such as aromatic polyamides, e.g. meta-xylylene adipamide; substituted or unsubstituted ethylenically unsaturated hydrocarbon, such as diene polymers such as polyisoprene, polybutadiene (especially 1 ,2-polybutadienes, which are defined as those polybutadienes possessing greater than or equal to 50% 1 ,2 microstructure), and copolymers thereof, e.g. styrene-butadiene; polymeric compounds such as polypentenamer, polyoctenamer, and other polymers prepared by olefin metathesis; diene oligomers such as squalene; and polymers or copolymers derived from dicyclopentadiene, norbornadiene, 5-ethylidene-2- norbornene, or other monomers containing more than one carbon-carbon double bond (conjugated or non-conjugated); carotenoids such as beta -carotene; substituted ethylenically unsaturated hydrocarbons such as those with oxygen-containing moieties, such as esters, carboxylic acids, aldehydes, ethers, ketones, alcohols, peroxides, and/or hydroperoxides; suitable hydrocarbons include condensation polymers such as polyesters derived from monomers containing carbon-carbon double bonds; unsaturated fatty acids such as oleic, ricinoleic, dehydrated ricinoleic, and linoleic acids and derivatives thereof, e.g. esters; suitable hydrocarbons also include polymers or copolymers derived from (meth)allyl (meth)acrylates.

The composition used may also comprise a mixture of two or more of the substituted or unsubstituted ethylenically unsaturated hydrocarbons described above.

The oxygen scavenging materials used in the present invention may further comprise one or more transition metal catalysts. The catalyst(s) may be provided in the form of a salt, with the metal thereof selected from the first, second or third transition series of the Periodic Table. Antioxidants may be included within the formulation deployed in the aerosol to further facilitate or control the initiation of oxygen scavenging properties. The antioxidant within the context of the present invention may be suitable to inhibit any oxidative degradation and/or cross-linking of polymers. The aerosol of the present invention may be used with a variety of propellant systems. In one embodiment the propellant may be a volatile hydrocarbon such as butane and/or propane.

In an alternative embodiment the propellant may be compressed gas, such as compressed air, compressed nitrogen and/or compressed crude nitrogen.

A further advantage of the aerosol of the present invention may be the possibility to reduce the amount of corrosion inhibitors used. This not only reduces the cost of raw materials but also makes formulating the composition to be sprayed less complicated.

Preferably the aerosols of the present invention are for use as domestic care products such as air fresheners, domestic cleaning products, fabric care, waxes, polishes, insecticides, ironing aids, fabric refreshers, carpet cleaners and the like.

The aerosol body of the present invention may comprise three separate parts, a base, a side wall and a top. In general construction the side wall would be fixed to the base by crimping the edge of the base around one end of the side wall followed by the crimping of the edge of the top around the other edge of the side wall, or vice versa. The top is typically provided with a centralised aperture into which a valve assembly can be connected by crimping an end of the valve assembly to the edge of the aperture in the top.

According to a second arrangement of the present invention there is provided therefore an aerosol comprising: a body having at least a base, a side wall and a top; at least one valve having an inlet located within the body and an outlet located outside of the body defining a fluid pathway therethrough from the interior of the body to the exterior of the aerosol; a valve actuator engaged with the valve outlet; a dip tube in communication with the valve inlet; characterised in that at least one of the base and/or the side wall and/or the top and/or the valve inlet and/or the dip tube has a surface facing an interior of the body comprising oxygen scavenging material.

Preferably at least two of the base and/or the side wall and/or the top and/or the valve inlet and/or the dip tube has a surface facing the interior of the body comprising oxygen scavenging material, and even more preferably at least three of the base and/or the side wall and/or the top and/or the valve inlet and/or the dip tube has a surface facing the interior of the body comprising oxygen scavenging material, and even most preferably at least four of the base and/or the side wall and/or the top and/or the valve inlet and/or the dip tube has a surface facing the interior of the body comprising oxygen scavenging material, and ideally the a base and the side wall and the top and the valve inlet and the dip tube has a surface facing an interior of the body comprising oxygen scavenging material.

The oxygen scavenger material is preferably incorporated into a plastics material which is coated on the interior-facing surface of one or more of the base, side wall, top, the valve inlet and the dip tube; the oxygen scavenging material preferably being incorporated with the plastics material of the by mixing the scavenger material as a masterbatch or additive in the plastics material during the manufacture thereof. Preferably substantially all of the interior-facing surface(s) is coated with said plastics material. The coating may be applied by spray coating and/or possibly in combination with any required binders or adhesives.

According to a third aspect of the present invention there is provided therefore a domestic care aerosol comprising: a body; at least one valve having an inlet located within the body and an outlet located outside of the body defining a fluid pathway from the interior of the body to the exterior of the aerosol; a valve actuator engaged with the valve outlet; a dip tube in communication with the valve inlet; characterised in that the dip tube comprises oxygen scavenging material.

According to a fourth aspect of the present invention there is provided therefore a valve assembly for an aerosol, the valve comprising an inlet intended to be located within a body of an aerosol and an outlet intended to be located outside of the body and a dip tube engaged with the valve inlet, characterised in that the dip tube comprises oxygen scavenging material.

According to a fifth aspect of the present invention there is provided therefore a dip tube for use with an aerosol valve assembly, wherein the dip tube is provided with a substantially elongate hollow cylindrical structure and the dip tube comprises oxygen scavenging material.

According to a sixth aspect of the present invention there is provided therefore a method of reducing the quantity of oxygen in an aerosol canister, the method comprises the steps of filling the canister with the composition to be sprayed from the canister is use, and then: sealing the canister using a valve assembly according to the third aspect of the present invention secured to a canister body and filing the canister with propellant; or filling the canister with propellant and then securing a valve assembly according to the third aspect of the present invention to a canister body of the aerosol.

Description of an Embodiment

An embodiment of the invention will now be described by way of example only. An aerosol generally comprises a canister body made of thin sheet material side walls, preferably tin-coated sheet steel. The side walls are shaped into a cylinder and sealed along the adjoining edge and is sealed around a bottom edge with a deformation cap. The deformation cap is concaved shaped dome which is secured to the side walls to extend into the interior of the body of the aerosol body. The deformation cap is a safety feature built into aerosols to provide the canister with an emergency means to increase its volume should the internal pressure in the canister surpass a predefined pressure in order to counteract the high internal pressure. The deformation cap is designed to fail at a predefined pressure and deform from a concave shape to a convex shape thus increasing the internal volume of the aerosol body and reducing the internal pressure of the aerosol.

The aerosol body is sealed at its top edge by being sealed to a valve. The valve is generally provided with an inlet located within the body and an outlet located outside of the body to define a fluid pathway therethrough from the interior of the body to the exterior of the aerosol. The valve is further provided with a valve actuator engaged with the valve outlet, this is capable of being actuated by a user or automated mechanical means to open the valve to release the contents of the aerosol into the surround environment and, once actuation is ceased, the actuator is operable to close the valve to prevent the continued release of the aerosol contents.

Connected to the valve inlet is a dip tube which may be elongate with a hollow cross section, the dip tube may extends into the interior of the aerosol, typically such that it touches or is adjacent to the deformation cap. The dip tube generally assists preventing the composition from blocking up the valve and restricting the flow of the composition from the aerosol.

Oxygen scavenging material is deployed in, on or with the dip tube to act to reduce the overall potential for corrosion inside the aerosol body. The oxygen scavenger material may assist in reducing the level of corrosion inhibitors required in the aerosol body. Furthermore, the oxygen scavenger may support a reduction in the amount of volatile hydrocarbon propellant required.

Deployment of oxygen scavenger material in, on or with the dip tube is further considered to be advantageous as it significantly simplifies the manufacturing process. No additional materials are required, so no additional manufacturing steps. Furthermore, such deployment also prevents the scavenging material from interfering with the performance of the aerosol.

The dip tube is commonly made of a plastics material and the oxygen scavenging material may be incorporated with the plastics material of the dip tube, such as by mixing the scavenger material as a masterbatch or additive in the dip tube plastics material during the manufacture thereof.

Alternatively or additionally, the dip tube has a portion thereof coated with the oxygen scavenging material.

The particular oxygen scavenging material selected can be tuned such that it is fit for the performance of the particular aerosol canister and composition loaded therein. For instance, in a 400ml aerosol canister using butane propellant would, on filing with composition, typically have a head space within the canister which could contain approximately 20ml of oxygen, therefore, the oxygen scavenging material in the dip tube should be capable of scavenging the majority-to-all of this oxygen.

Regulations are acting to reduce the amount of hydrocarbon propellants and, therefore, using alternative propellants are of increasing interest. Compressed gas is inexpensive but fraught with problems, not just the problems with oxygen being present in the canister. Using compressed nitrogen solves this latter problem but it is expensive to manufacture. However, compressed crude nitrogen is significantly less expensive to produce and is more readily available, as such, the deployment of oxygen scavenging material in the dip tube makes the use of crude nitrogen a more realistic commercial possibility.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.