WO2007083164A2

WO2007083164A2 - Liquid electrostatic spray composition

Info

Publication number: WO2007083164A2
Application number: PCT/GB2007/050025
Authority: WO
Inventors: Alastair Bruce Pirrie
Original assignee: Aerstream Technology Limited
Priority date: 2006-01-17
Filing date: 2007-01-17
Publication date: 2007-07-26
Also published as: WO2007083164A3

Abstract

The invention provides inter alia a liquid electrostatic spray composition consisting of: (i) a non-aqueous component which is substantially free of propellants and ethanol; and (ii) 0.1-25% w/w water component being water as adjuvant to modify the viscosity and/or resistivity and/or surface tension of the composition optionally together with additional electrolytes; the composition containing one or more active ingredients; and the composition having at 20°C a resistivity in the range 1 x 103 to 1 x 106 Ωm, a viscosity in the range 1 to 5 cP and a surface tension in the range 20-40 mN/m.

Description

LIQUID ELECTROSTATIC SPRAY COMPOSITION

BACKGROUND OF THE INVENTION Field of the Invention This invention relates to novel compositions suitable for atomisation in a spray device, in particular an electrostatic spray device in which atomisation is achieved by the application of an electric potential between a spray electrode and a reference electrode. Such compositions are useful for the dispersion of active agents such as fragrances, pest control agents, antimicrobials, anti-allergenics or medicaments. The invention also relates to spray devices employing said compositions and to their use in industrial applications. Description of the Related Art

Methods for the dispersal of active compounds are known and may be achieved in a number ways, for instance: propulsion of a pressurised composition in conjunction with a gas propel lant, atomisation using a vibrating plate (i.e. piezoelectric atomisation), accelerated evaporation from a heated wick, volatilisation from an impregnated matter and by electrostatic spraying.

Propulsion of a pressurised composition in conjunction with a gas propellant typically produces a dispersion of said composition with droplet sizes dependent on the ratio of product to propellant, the valve aperture, the actuator nozzle aperture and the shape of the actuator aperture. US Patent No. 6,592,813 discloses an aerosol spray device which produces droplets with a range of diameters of 5 to 100 urn with a peak around 40 urn. The compositions disclosed therein contain 10-90% (especially 30-40%) w/w propellant such as butane and contain a substantial aqueous component, typically around 60% w/w. The reliance of such devices on hydrocarbon propellants is unsatisfactory and the droplet sizes produced are relatively large.

Piezoelectric atomisation devices deliver active components by ultrasonic vibration of an orifice plate to which a liquid is applied. Droplet size is determined by the diameter of orifices in the orifice plate, so that for example a 5 urn droplet will be formed by an orifice of 3-4 urn. Orifices of small diameter, namely less than 10 microns may be subject to clogging by solid matter in the dispersal composition or by ambient dust and grit particles. International Patent Application publication number WO 02/47482 discloses compositions which are deliverable by piezoelectric devices and which stated to avoid undesirable evaporation from the orifice(s). These compositions typically comprise up to 97% polar solvents such as glycol ethers and a vapour pressure below 5 mm Hg at 25⁰C. Because of the aforementioned clogging problem, piezoelectric devices are limited to compositions having a low viscosity (for example less than 10 cP), necessitating that viscous agents be grossly diluted with low viscosity solvents (although this raises additional issues of clogging due to solvent evaporation when the device is not in use). This functional requirement limits the range of usable compositions, and for example where fragrances are being used, can limit the aromatic strength of the composition. Low viscosity often corresponds to high vapour pressure, and such high vapour pressure compounds usually have a much lower nasal threshold concentration, meaning that a higher concentration of compound in the air is required to create the same level of perceived aroma. Ultimately, this means that piezoelectric devices tend to produce weak aromas as a direct result of these composition restrictions, which makes them commercially disadvantageous.

Active compounds may be dispersed by evaporation from a heated wick, an example of which is disclosed in US Patent No. 6,580,875. Compositions dispersed by wick devices are susceptible to lag as the heating element warms the composition for evaporation. Once the wick is suitably heated, there is a lag after demand for the active has been met, which may result in over-dispersal of the active. Compositions for use with wick devices are typically polar, including water, alkyl alcohols and glycols and there is no realistic manner of regulating droplet sizing.

Impregnated matter may be used for dispersing active components through thermal volatilisation of active components. Devices using such impregnated members typically heat the member when there is a demand for the active component. Devices such as these, an example of which is disclosed in US Patent No. 4,214,146, may not be efficient at dispersion if there is poor air circulation around the device. In addition, there may be waste as the active compound condenses in the nearby cooler environment. Where circulation is said to be improved, as with the device disclosed in US Patent No. 4,725,712, there may be a time lag from the initialisation of the heating process and actual release of active compounds. Further, there may be a delay before release of the volatilised active components cease emission from the device resulting in an unexpected level of exposure to the active component. There is no easy method of controlling droplet size using such devices. Electrostatic spraying is known in the art and is exemplified in European Patent

1399265. Atomisation of liquids is achieved through the generation of a high specific surface area of a liquid by electronic means. Dispersion of active ingredients carried in a liquid composition is achieved once a potential difference is applied between a spray electrode (from which the liquid is dispensed) and a discharge electrode, each of which is housed in a dielectric medium. A substantially dry spray may be produced consisting of droplets of suitable dimension to be carried in the air and which do not sink to the ground under the influence of gravity. For a given composition, the diameter of the droplets can (at least to some extent) be controlled by varying the applied voltage and liquid flow rate experimentally. Droplets are initially carried away from the spray electrode according to the local electric field. Their subsequent discharge by the discharge electrode in the proximity of the dielectric medium prevents attraction of the droplets back to the device. The emission of the active containing composition ceases immediately the potential difference between the electrodes is equalised. The system is thus extremely efficient. The aperture of the spray electrode may be orders of magnitude greater than the resultant droplet size and thus the dispensing system is less susceptible to clogging by dust or grit.

Compositions suitable for dispensing using electrostatic spray devices are known in the art. US Patent No. Re. 31,927 discloses compositions consisting of high-boiling point hydrocarbon solvents such as "Solvesso" 150, "Isopar L" and "Exsol" D180/220 in combination with long chain chlorinated hydrocarbons such as "Cereclor" C42 and C48 which are added to increase viscosity, and polar solvents such as alcohols and in particular ketonic solvents which are added so as to lower the resistivity. Alternatively, suitable compositions could be produced consisting of mixtures of hydrocarbons and long-chain chlorinated hydrocarbons dosed with an antistatic agent. It is stated in US Patent No. Re. 31,927 that the compositions disclosed therein should be protected from any further contamination, especially by water. As disclosed therein, these compositions are suitable for producing droplets with a range of mean droplet sizes of from about 50 to 200 microns in diameter, with resistivities in the range 1 x 10⁴ - 1 x 10⁸ Ωm, preferably in the range 1 x 10⁴ - 5 x 10⁶ Ωm, and viscosity 1 - 50 centiStokes, preferably greater than 10 centiStokes. It is known that droplet sizes in the range resulting from these compositions are inappropriate for slow and stable release of active components and for efficient dispersal on ambient air currents. Accordingly, there may be substantial wetting in the proximity of the dispensing device unless the large droplets are assisted in their distribution by a device such as a fan or convection current. It is further known that Solvesso 150 is designated as harmful by inhalation and by swallowing (R20/22) and irritating to skin and eyes (R36/38). It is further known that Solvesso 150 contains a category 2B carcinogen according to International Agency for Research on Cancer classification and is designated as harmful and may cause lung damage if swallowed (R65).

US6,595,208 discloses an electrostatic spray device which employs a composition containing around 80% v/v ethanol, 20% v/v propylene glycol and 2% m/v salbutamol.

However, compositions containing ethanol are to be avoided in many situations for economic, health, ethical and/or religious reasons.

US6,794,416 discloses an electrostatic spray composition containing 0.1% 13-cis retinoic acid, 10% emulsifier, 3% polyethylene glycol and 86.9% water by weight. Highly aqueous compositions have, for electrostatic spray applications, unsuitably high surface tension unless surfactants (which are generally undesirable) are added. Further, many active ingredients are not miscible with water therefore such a composition system would be expected to have limited applicability.

GB2022418A discloses formulations for spraying water soluble agents wherein the formulations comprise water-in-oil emulsions, the aqueous phase being 1 to 50% by weight, together with an additional emulsifying agent. Emulsions may be aesthetically unappealing to a customer where the purity or quality of a composition is an important consideration and may not be sufficiently long-lived to permit the homogenous dispersion of the matter which is to be sprayed. Where emulsifying agents are employed to avoid these problems, the agents may add unnecessary complexity and expense to the process of blending a composition. Furthermore, where an emulsifying agent is ionic, it may interact unfavourably with a charged active component of the composition. EP1023832A1 discloses concentrates for stable suspensions for crop treatment, although not by electrostatic spraying, where the concentrates require at least 20% water w/w. Summary of the Invention

It is an object of the invention to provide a composition suitable for electrostatic dispersal of active components, especially as small droplets. It is a further object of the invention to provide a composition which poses low toxicity and low hazards to humans upon dispensing and/or handling and transporting of the composition and/or otherwise avoids the use of undesirable constituents such as propellants and ethanol. It is a further object of the invention to provide a composition which does not suffer from the problem of deposition when employed in an electrostatic spray device, such as that described in EP-A-1399265. It is a further object of the invention to provide a composition which is less susceptible to manufacturing variability due to contamination of constituents with water or other like polar substances. It is a further object of the invention to provide a composition the electrostatic dispersal rate of which may be modified simply without resorting to modification of the properties of the electrostatic spray device. It is a further object of the invention to provide a composition the electrostatic dispersal rate of which may be modified simply without resorting to the doping of the composition with harmful or hazardous chemicals.

Some or all of these and other objects of the invention may be achieved by providing a composition according to the invention.

Thus, as a first aspect of the invention, we provide a liquid electrostatic spray composition consisting of:

(i) a non-aqueous component which is substantially free of propellants and ethanol; and

(ii) 0.1-25% w/w water component being water as adjuvant to modify the viscosity and/or resistivity and/or surface tension of the composition optionally together with additional electrolytes; the composition containing one or more active ingredients; and the composition having at 2O⁰C a resistivity in the range 1 x 10³ to 1 x 10⁶ Ωm, a viscosity in the range 1 to 5 cP and a surface tension in the range 20-40 mN/m.

As a second aspect of the invention, we provide an electrostatic spray device reservoir containing a composition according to the first aspect of the invention. As a third aspect of the invention we provide an electrostatic spray device comprising a spray electrode into which the composition to be sprayed is fed from a reservoir, a reservoir containing composition to be sprayed (being a composition according to the first aspect of the invention), and a reference electrode in the vicinity of the spray electrode; such that upon application of electric potential across the electrodes the composition is sprayed from the spray electrode in the form of droplets.

As a fourth aspect of the invention we provide the use of a composition according to the first aspect of the invention in an electrostatic spray device. As a fifth aspect of the invention we provide a process for dispensing an active ingredient which comprises taking a composition according to the first aspect of the invention and delivering it from an electrostatic spray device. Advantageously the active ingredient may be dispensed in the form of small droplets (e.g. droplets of volume median diameter less than 10 microns). Suitably the composition of the invention should remain within the above stated physical property window (i.e. in terms of resistivity, viscosity and surface tension) over the entire range of temperatures expected during normal operation. More often or not this is room temperature (say between 18 and 25⁰C e.g. at 2O⁰C) which is therefore the optimum temperature range. However, the compositions disclosed under this invention will typically operate from O⁰C to above 4O⁰C without modification, and often also outside this range.

A surprising aspect of the invention is that the presence of a relatively small amount of water (as defined herein) in the composition is far from deleterious to its properties, as suggested by US Patent No. Re. 31 ,927, but in fact allows the consistent generation of small droplets with little susceptibility to deposition when employed in an electrostatic spray device (such as that disclosed in EP-A-1399265). Furthermore, the use of water in this way permits other more hazardous potential constituents to the composition to be avoided. The present invention is highly versatile with application to a wide range of active ingredients, including those not generally thought to be water miscible (such as many fragrances and pest control agents) and for which hitherto formulation with water has been avoided. Brief description of the drawings

Figure 1 shows an electrostatic spray device suitable for dispensing compositions according to the invention. Detailed Description of the Preferred Embodiments

Compositions of the invention will be substantially free of ethanol i.e. the ethanol content will have essentially no impact on the properties of the composition. Typically any ethanol content will be less than 5%, especially less than 1% (e.g. less than 0.1%) w/w. Ideally the amount of ethanol will be undetectable in the composition once dispensed (i.e. undetectable by taste or smell).

Compositions of the invention will be substantially free of propellants i.e. the propellant content will have essentially no impact on the properties of the composition. Typically any propellant content will be less than 5%, especially less than 1% (e.g. less than 0.1%) w/w. Propellants are low boiling point substances (i.e. liquefied gases) which have appreciable vapour pressure at ambient temperature, e.g. substances which have a boiling point of less than O⁰C (e.g. less than -4O⁰C) at atmospheric pressure (i.e. 1.025 x 10⁵ Pa). Example propellants to be avoided include lower hydrocarbons such as propane and butane. Other example propellants to be avoided include CFCs (chlorofluorcarbons) such as Propel lant 12 and HFAs (hydrofluoroalkanes) such as HFA134a and HFA227. Suitably the water content of the composition is 0.1-15%, especially 1-10% (e.g. around

2-6%) w/w. Water should not be used in an amount which exceeds its solubility limit in the composition under normal conditions of use (e.g. at 0-40⁰C, especially between 18 and 25⁰C, e.g. 2O⁰C). The composition suitably consists of a single homogeneous phase.

Suitably the resistivity of the composition is 1 x 10³ to 1 x 10⁵ Ωm, e.g. 1 x 10⁴ to 1 x 10⁵ Ωm.

Suitably the viscosity of the composition is 1-4 cP, e.g. 2-3 cP.

Suitably the surface tension of the composition is 20-35 mN/m, eg 25-35 mN/m, such as 29-33 mN/m, for example 27-31 mN/m.

Suitably when the water as adjuvant modifies the viscosity of the composition it lowers the viscosity of the composition. Suitably when the water as adjuvant modifies the resistivity of the composition it lowers the resistivity of the composition. Suitably when the water as adjuvant modifies the surface tension of the composition it raises the surface tension of the composition.

The non-aqueous component may consist of the one or more active ingredients. Alternatively the non-aqueous component will comprise or consist of a carrier in which (together with the water) the one or more active ingredients are dispersed or more suitably are dissolved. For example the carrier may be a solvent e.g. an organic solvent. Solvents may be polar or apolar but will typically be polar.

For the most efficient, effective and safe dispersion of the active component, a stable spray of small droplets should be produced by the electrostatic spray apparatus and the composition must thus ideally satisfy certain constraints. The constraints include: (1) the ability to dissolve the active ingredient(s) or otherwise to allow the active ingredient(s) to be dispersed i.e. uniformly distributed in the composition, (2) appropriate resistivity, viscosity and surface tension and (3) low toxicity (low risk designations). Additionally, it will normally be desirable that the compositions are also constrained by the requirement of being (4) low hazard e.g. raised flash point.

As is known in the art, the resistivity, viscosity and surface tension of a composition is primarily dependent on the resistivity, viscosity and surface tension of the solvents and other liquids employed to make the composition. There may be an additional effect on the properties of the composition due to the presence of any dissolved active component and additional electrolytes.

It has been an object of this invention to reduce (or to minimize or to eliminate) the exposure to humans of risks associated with the compositions. In particular, we have sought to reduce or eliminate the use of substances, particularly carriers, which are or may be harmful to humans. Suitable carriers comprise, and for example consist of, polyols (excluding ethanol) and polyol ethers such as glycol ethers e.g. glycol methyl ethers. Particularly suitable polyol ethers include dipropylene glycol methyl ether ((2-methoxymethylethoxy)propanol, Dowanol DPM) and propylene glycol methyl ether (i-methoxy-2-propanol, Dowanol PM), especially dipropylene glycol methyl ether. Another suitable polyol ether is tripropylene glycol methyl ether (2-(2- methoxymethylethoxy)methylethoxy)propanol, Dowanol TPM). Other example carriers include polyethylene glycols e.g. polyethylene glycols of molecular weight 200-400 Da. Additional example carriers include ethylene glycol and propylene glycol. Further example carriers include 1 -methoxy-2-propanol acetate (Dowanol PMA), 1-(2-butoxy-2-methylethoxy)-2-propanol (Dowanol DPNB), 1-(2-propoxy-2-methylethoxy)-2-propanol (Dowanol DPNP), 1 -methoxy-2- acetoxypropane (Dowanol PMA), 1 -butoxy-2-propanol (Dowanol PNB) and 1-propoxy-2- propanol (Dowanol PNP), and oxybis(methoxy)-propane (Proglyde DMM).

A particularly suitable carrier is a mixture of dipropylene glycol methyl ether and propylene glycol methyl ether used for example in a ratio of 1 :9 to 9:1 w/w, i.e. the carrier consists of 10-90% w/w dipropylene glycol methyl ether and 10-90% w/w propylene glycol methyl ether.

In some situations the carrier may incorporate a component which can modify its physical properties especially the resistivity, viscosity and/or surface tension of the carrier not incorporating that component (for example, such that the aforesaid physical properties are closer to the required range). For example, it may be desired to lower the surface tension of a glycol ether carrier by adding an isoparaffin such as lsopar L. For example, it may be desired to increase the viscosity of a glycol ether or a lower molecular weight polyethylene glycol carrier by adding a relatively high molecular weight polyethylene glycol, such as a polyethylene glycol of molecular weight above 400 Da, e.g. 500-700 Da. The carrier may, for example, consist of isoparaffin 0-5% w/w with the remainder a mixture of dipropylene glycol methyl ether and propylene glycol methyl ether (used for example in a ratio of 1 :9 to 9:1 w/w). Suitably the carrier may consist of 0 - 10% w/w, typically 2-8%, i.e., 3 - 5% w/w, isoparaffin with the remainder comprising dipropylene glycol methyl ether, for example a mixture of dipropylene glycol methyl ether and propylene glycol methyl ether (used for example in a ratio of 1 :9 to 9:1 w/w). In certain embodiments of the invention the water component will contain minimal electrolyte (for example no additional electrolyte, or less than 0.001% w/w, in particular less than 0.0001% and especially less than 0.00001% electrolyte based on the weight of the water component). The resistivity of the water component will typically be at least 0.01 x 10³ Ωm, especially at least 1 x 10³ Ωm, in particular at least 1 x 10⁴ Ωm and suitably at least 1 x 10⁵ Ωm (for example at least 1 x 10⁶ Ωm, such as at least 10 x 10⁶ Ωm). Suitably the water component is deionised or HPLC grade water or similar.

In other embodiments of the invention additional electrolytes may be added to the composition (by inclusion in the water component) in order to reduce resistivity. Thus an additional electrolyte is a substance added for the purpose of reducing resistivity in the formulation relative to a formulation without the additional electrolyte. It is to be understood that in preparation of the formulation the additional electrolyte(s) may be pre-dissolved in the water or may be added to the formulation separately from the water (e.g. by addition to a water containing formulation).

Suitable additional electrolyte substances that may be added include sodium hydrogen carbonate, sodium chloride, ascorbic acid, citric acid and acetic acid.

Thus, additional electrolytes may typically be acids and salts of acids. By way of further example and without limitation, suitable additional electrolyte substances also include: (a) derivatives of carboxylic acids, such as:

(i) alkanoic, alkenoic and alkynoic acids;

(ii) substituted alkanoic, alkenoic and alkynoic acids;

(iii) aromatic carboxylic acids; and (b) carboxylate salts (e.g. salts of (i), (ii) or (iiii)). Alkanoic, alkenoic and alkynoic acids will typically have between 1 and 20 (such as 1 to

10, e.g. 1 to 6) carbon atoms in total. Alkanoic, alkenoic and alkynoic acids may be straight chain or branched, though will typically be straight chain. Exemplary alkanoic acids include carboxylic acid derivatives of the alkyl groups methyl (i.e. formic/methanoic acid), ethyl (i.e. acetic/ethanoic acid), propyl (including n-propyl and iso-propyl), butyl (n-butyl, sec-butyl and tert-butyl), pentyl (e.g. n-pentyl, iso-pentyl, 4-methylbutyl), hexyl (e.g. n-hexyl). Alkenoic and alkynoic acids will contain at least one (for example 1 to 3, especially 1 or 2 and in particular 1) double or triple bond respectively.

Substituted alkanoic, alkenoic and alkynoic acids include alkanoic, alkenoic and alkynoic acids having one or more (e.g. 1 or 2, in particular 1) substituent groups selected from: hydroxyl, amino or additional carboxylic acid functions (e.g. to provide diacids or triacids).

One particular set of substituted alkanoic acids which are embraced by the present invention includes amino acids, especially the 20 common amino acids (L- isomers, D-isomers and racemic or other mixtures thereof, especially the natural L- isomers).

Aromatic carboxylic acids include benzoic acid. Exemplary carboxylate salts include monovalent cation salts (e.g. sodium or potassium salts). Alternative carboxylate salts include of divalent cation salts (e.g. magnesium salts).

Particular alkanoic acid salts include sodium acetate or potassium acetate.

Examples of substituted alkanoic acids are lactic acid (2-hydroxypropanoic acid) and tartaric acid (2,3-dihydroxybutanedioic acid). One of the salts of lactic acid which may be used in the invention is sodium lactate. Exemplary salts of tartaric acid include both tartrate and bitartrate salts.

An example of an amino acid is glycine. Furthermore, suitable additional electrolytic substances include amines and their derivatives, such as polyamines and hydroxylamines, for example 2-amino-2-hydroxymethyl- 1 ,3-propanediol. Other possible electrolytic substances include quaternary ammonium salts.

Suitably the additional electrolyte derivative of a car boxy lie acid is not citric acid. Suitably the additional electrolyte salt of derivative of a carboxylic acid is not a citric acid salt. When additional electrolytes are added to the composition the physical properties are less sensitive to any electrolyte impurities that may be present within other components of the composition (which may be advantageous in ensuring reproducibility between batches). When additional electrolytes are included a suitable quantity is typically 0.001-2% (such as 0.01-2%, e.g. 0.1-2%) in particular 0.001-1% (such as 0.01-1%, e.g. 0.1-1%) w/w based on weight of the water component. Suitably, the amount of additional electrolyte in the composition is less than 0.01% based on the weight of the composition. Those skilled on the art will recognise that the optimal amount of electrolyte will depend upon may factors, such as the specific additional electrolyte used and the other ingredients (i.e. carriers, active agents etc) present in the composition.

By way of example, without limiting the invention, an active ingredient may comprise, and in particular may be: a fragrance; a pest control agent, such as an insect repellant, an insect attractant an insecticide or a synergist; an air sanitizer, such as an air-cleaner or freshener, an anti-microbial (e.g. an anti-viral or anti-bacterial), an anti-fungal or an anti- allergenic (which may include compounds known to neutralize or denature allergens); or a medicament.

Active ingredients may be present in the composition in an amount of typically 0.01- 99.9% w/w.

Active fragrance ingredients of a composition may include for example essential oils and other fragrance oils (natural and synthetic), containing components such as 2,3 butanedione, 2,3 pentandione, 2,4-dimethylcyclohex-3-enyl-carboxaldedyde, 2-ethyl-3,5-dimethylpyrazine, 2- isobutyl-3-methoxypyrazine, 2-isopropyl-3-methoxypyrazine, 2-methyl-3-(isopropyl phenyl) propanal, 3-carboxymethyl-2-pentylcylcopentane, 3-hydroxy-4,5-dimethyl-2-furanone, 3- isocamphylcyclohexanol, 3-methyl-2-pentyl-2-cyclopentenone, 4-(4-hydroxy-4-methylpentyl)-3- cyclohexane, carboxyaldehyde, 4-acetoxy-3-pentyl tetrahyd ropy ran, 4-hydroxy-2,5-dimethyl-3- furanone, 5-ethyl-3-hydroxy-4-methyl-2-furanone, 5-ethyl-4-hydroxy-2-methyl-3-furone, acetyl dedrene, aldehyde MNA (2-methyl-undecanal), alpha-ionone, amyl salicylate, benzyl acetate, benzyl alcohol, benzyl benzoate, benzyl salicylate, butanol, camphor, cedryl methyl ether, cis-3- hexenol, citronellol, citronellyl nitrile, coumarin, damascenone, decanol, dimethyl benzyl carbinol, diphenyl oxide, ethyl butyrate, ethyl malonate, ethyl-2-methyl butyrate, ethylene brassylate, eucalyptol, eugenol, geraniol, geranyl nitrile, gamma methyl ionone, greenyl acetate, guaiacol, habanolide, heliotropin, heptyl acetate, hexanal, hexanol, hexyl acetate, hexyl salicylate, hexyl-2-methyl butyrate, hexylcinnamaldehyde, hydroxy citronellal, indane, tetraline, isochroman musks, ionone, isoamyl alcohol, isobornyl acetate, iso butyl quinoline, isopentenyl acetate, lilialdehyde, limonene, linalool, menthol, methyl cedryl ketone, methyl dihydrojasmonate, methyl salicylate, myrcemol, nopol, octanol, OTNE (1-(1 , 2,3,4,5, 6,7,8- octahydro-2,3,8,8-tetramethyl-2-naphthalenyl)ethanone), parmetol, phenethenol, phenoxylethylisobutrate, phenyl acetaldehyde diethyl acetal, prenyl acetate, p-tert- butylcyclohexyl acetate, styrallyl, terpinol, trans-2-hexanal, trans-2-hexenol, vanillin, vanoris (isononyl acetate), verdox (1-acetyl-2-tertbutylcyclohexane) and vetiveryl acetate.

Suitably the active component is a fragrance oil which may be employed at a concentration of typically 1-99.9% w/w, for example 10-99.9% w/w (e.g. 20-99.9%). Active insecticide ingredients of a composition may include, for example, pyrethroid compounds including:

- pyrethrins (such as pyrethrins 1 , 3 and 11 ), e.g. as 25 % or 50 % pyrethrum extract (the balance typically containing plant oils, other plant extracts and light paraffin oils);

- allethrins and related non-natural compounds, including d-allethrin, bioallethrin, esbiothrin (EBT), S-bioallethrin (S-Biol); resmethrin and bioresmithrin; bifenthrin, permethrin, deltamethrin, cypermethrin, alpha-cypermethrin, cyphenothrin, lambda- cyhalothrin, vaporthrin, transfluthrin, prallethrin and selected isomers such as Etoc, tefluthrin, pynamin, pynamin forte, neopynamin, metofluthrin, sumithrin, and imiprothrin. Active insecticide ingredients of a composition may also include organic phosphorus compounds including, but not limited to, fenitrithion, malathion, ciafos, diazinon, DDVP (dichlorvos), and carbamate compounds including carbarγl.

Active pest control ingredients include synergists, for example piperonyl butoxide which may suitably be used in combination with insecticides such as pyrethrins and other pyrethroids. Active insect attractant ingredients include mosquito and tsetse fly attractants such as octenol.

Active insect repellant ingredients of a composition include, for example, citronella, DEET (N,N-diethyl-meta-toluamide) or D-limonene.

Active air-cleaner or freshener ingredients, active anti-microbial ingredients, active antifungal ingredients and active anti-allergenic ingredients (which may include compounds known to neutralize or denature allergens), which may collectively be classed as active air sanitizers, may include, for example, n-alkyl dimethyl benzyl ammonium chlorides, n-alkyl dimethyl ethyl benzyl ammonium chlorides, alkyl dimethyl 1-naphthylmethyl ammonium chloride, benzalkonium chloride, 1,2-benzisothiazolin-3-one, isopropanol, orthobenzylparachlorophenol, orthophenylphenol, paratertamylphenol, potassium peroxomonosulphate, sodium dodecyl benzene sulphonate, and sodium hypochlorite. Furthermore, active air sanitizers may include, for example, compounds which are known to have antioxidant, stabilising or other desirable properties (in particular those which are approved for human consumption), such as salts of acetic acid, salts of benzoic acid, salts of butyric acid, salts of citric acid, salts of lactic acid, salts of propanoic acid, salts of tartaric acid. One skilled in the art will recognise that air sanitizers have the potential to act as surface sanitizers through their deposition on surfaces.

Glycols (including dipropylene glycol, propylene glycol, triethylene glycol) may also be used as active air sanitizer components when they are not included as or within the carrier. Active ingredients such as pest control agents and air sanitizers are typically present in the composition at around 0.01-50% w/w (such as 0.1-50% or 0.01-15% w/w, e.g. 0.1-15% w/w).

Active medicament ingredients of a composition may include, for example, ingredients which are diuretics (including bumatenide, furosemide, hydrochlorothiazide, melalazone, spironolactone, torsemide), hypotensive agents (including amiodarone, flecainide, procainamide, sotalol), vasodilators (including benazopril, captopril, enalapril, fosinopril, hydralazine, isosorbide dinitrate, isosorbide mononitrate, lisinopril, moexipril, perindopril, quinapril, ramipril), or otherwise suitable for treating cardiac conditions (including acebutolol, amlodipine, aspirin, atenolol, bepridil, caffeine, candesartan, irbesartan, losartan, valsartan, warfarin, busoprolol, carvedilol, diltiazem, digitoxin, dobutamine, esmolol, felodipine, labetalol, metoprolol, milrinone, nicardipine, nicotine, nifedipine, nisoldipine, propanolol, timolol, verapamil). Active medicaments ingredients of a composition may further include, for example, ingredients which are anti-microbial i.e. anti-bacterial or anti-viral (including, acyclovir, adefovir, amantidine, amoxicillin, amoxicillin-clavulanate, ampicillin, azithromycin, cefaclor, cefdinir, cefpodoxime proxetil, cefriaxone, cefotaxime, cefuroxime, cefuroxime acetil, clarithromycin, ciprofloxacin, clavulanate potassium, doxycycline, entecavir, famiciclovir, gatifloxacin, gentamicin sulphate, glycyrrhizin , interferon alfa-2b, lamivudine, loracarbef, minocycline, moxifloxacin hydrochloride, oseltamivir, peniciclovir, penicillins, riampin, ribavirin, rimantidine, telithromycin, trimethoprim/sulfamethoxazole, valacyclovir, valacycolvir hydrochloride, vancomycin, zanamivir, zidovudine) or anti-fungal (e.g. clotrimazole or fluconazole). Active medicaments ingredients of a composition may additionally include, for example, ingredients which are suitable for treating bronchial, pulmonary or rhinal conditions (including albuterol, alupent, beclomethasone, beclomethasone dipropionate, bitolerol mesylate, bosentan, budesonide, cromolyn, ephedrine, epinephrine, flunisolide, fluticasone propionate, formoterol, guaifenesin, L-albuterol, mometasone, mometasone furoate, montelukast, nedocromil, omalzimab, pseudophedrine, salmeterol, tertbutaline sulphate, theophylline, triamcinolone, triamcinoline acetonide, zafirlukast, zielutin). Active medicaments ingredients of a composition may further include, for example, ingredients which are anti-histamine or otherwise anti- inflammatory (including azelastine, cetirizine hydrochloride, chlorpheniramine maleate, desloratadine, dimetane, diphenhydramine hydrochloride, loratadine, phenylephrine). Active medicaments ingredients of a composition may also include, for example, ingredients which are anti-depressant (including amitriptyline, amoxapine, citalopram, clomipramine, desipramine, doxepin, fluoxetine, furazolidone, imipramine, linezolid, maprotiline, nortiptyline, paroxetine, phenelzine, protriptyline, selegiline, sertraline, tranylcypromine). Active medicaments ingredients of a composition may further still further include, for example, ingredients which are suitable for treating glaucoma (including apraclonidine hydrochloride, betaxolol hydrochloride, brimonidine tartrate, carteolol hydrochloride, dipivefrin hydrochloride, dorzolamide hydrochloride, levobunolol hydrochloride). Active medicaments ingredients of a composition may also include, for example antineoplastic agents (including anastrozole, bicalutamide, carbiplatin, cisplatin, docetaxel, etoposide, exemestane, flutamide, gefitinib, gemcitabine, irinotecan, megestrol, letrozole, nilutamide, paclitaxel, tamoxifen citrate, vinorelbine). Active medicaments ingredients of a composition may yet further include, for example, ingredients which are anti-spasmodic and/or anti-Parkinsonnian agents (including amomorphine, belladonna, benztropine mesylate, biperiden hydrochloride, bromocriptine, carbidopa, entacapone, glycopyrrolate, levodopa, orphenadrine citrate, pergolide, pramipexole, procyclidine hydrochloride, ropinirole, selegiline, talcapone, trihexyphenidyl hydrochloride). In addition, active medicaments ingredients of a composition may include, for example ingredients which have anaesthetic properties (including, benzocaine, bupivacaine, chloroprocaine, lidocaine, mepivacaine, nesacaine, prilocaine, procaine, tetracaine). Active medicaments ingredients of a composition may also include, for example keratolytic agents (including anthralin, calcipotriene, salicylic acid, tazarotene) and PDEV (Phosphodiesterase-V) inhibitors such as sildenafil, vardenafil, tadalafil and nicotinic receptor agonists e.g. nicotine. Active medicament ingredients of a composition may further include, for example, ingredients which are analgesic (including, acetaminophen, capsaicin, celecoxib, choline magnesium trisalicylate, codeine, etodolac, hydrocone, ibuprofen, indomethacin, ketoprofen, ketorolac tromethamine, meloxicam, methyl salicylate, morphine, nabumetone, naproxen, naproxen sodium, oxaprozin, oxycodone, paracetamol, D-phenylalanine, piroxicam, propoxyphene, salsalate, sulindac, tramadol, valdecoxib). Active ingredients such as medicaments are typically present in the composition at around

0.01-50% w/w (such as 0.01-5% w/w, e.g. 0.1-5% w/w).

The composition may include one active ingredient or a mixture of ingredients from one class (e.g. the class of pest control agents - for example pyrethrins and pyrethroids above could be used in combination) or from a mixture of classes (e.g. a pest control agent and a fragrance). Certain substances may themselves be a mixture of compounds e.g. fragrance oils often contain a mixture of chain lengths and pest control agent substances may contain a mixture of stereoisomers.

For example a fragrance at 5-50% may be combined with a pest control agent at 0.1-15% w/w. It may be noted that a number of the aforementioned active agents may themselves have electrolytic properties. Electrolytic active agents which are present in the composition in a quantity at which they do not demonstrate the properties of active agents, i.e. fulfilling their intended active function either in isolation, or in combination with additional agents in the same class, (e.g. in some cases when present at less than 0.5% w/w based on weight of the composition, such as less than 0.1% or 0.01%) are considered to be additional electrolytes.

A composition according to the invention may typically consist essentially of:

10 to 99 % w/w active ingredient; 1-15% w/w water; and

0-89% w/w carrier.

Alternatively a composition according to the invention may typically consist essentially of:

10 to 99 % w/w active ingredient; 1-15% w/w water and electrolyte; and

0-89% w/w carrier

Alternatively when the active ingredient is a fragrance, a composition according to the invention may typically consist essentially of:

10 to 99% w/w fragrance oil; 1-15% w/w water; and

0-89% w/w carrier.

10 to 99% w/w fragrance oil; 1-15% w/w water and electrolyte; and

0-89% w/w carrier.

Alternatively when the active ingredient is a pest control agent, such as an insecticide, a composition according to the invention may typically consist essentially of:

0.01 to 15% w/w eg 0.1 to 15% w/w pest control agent; 1-15% w/w water; and

70-98.9% w/w carrier.

0.01 to 15% w/w eg 0.1 to 15% w/w pest control agent; 1-15% w/w water and electrolyte; and

70-98.9% w/w carrier.

Alternatively when the active ingredient is a pest control agent such as an insecticide in combination with a fragrance oil, a composition according to the invention may typically consist essentially of: 0.01 to 15% w/w eg 0.1 to 15% w/w pest control agent;

5 to 50% w/w fragrance oil;

1-15% w/w water; and

20-93.9% w/w carrier. Alternatively when the active ingredient is a pest control agent such as an insecticide in combination with a fragrance oil, a composition according to the invention may typically consist essentially of:

0.01 to 15% w/w eg 0.1 to 15% w/w pest control agent; 5 to 50% w/w fragrance oil;

1-15% w/w water and electrolyte; and

20-93.9% w/w carrier for example it may consist essentially of:

2 to 8% w/w pest control agent; 5 to 50% w/w fragrance oil;

1 - 15% w/w water and electrolyte; and

27 - 92% w/w carrier.

Alternatively when the active component comprises a medicament a composition according to the invention may typically consist essentially of: 0.01 -to 50% w/w medicament;

1-15% w/w water; and

35-98.99% w/w carrier for example it may consist essentially of:

0.01 -to 5% w/w medicament; 1-15% w/w water; and

80-98.99% w/w carrier.

Alternatively when the active component comprises a medicament a composition according to the invention may typically consist essentially of:

0.01 -to 50% w/w medicament; 1-15% w/w water and electrolyte; and

35-98.99% w/w carrier for example it may consist essentially of:

0.01 -to 5% w/w medicament;

1-15% w/w water and electrolyte; and 80-98.99% w/w carrier.

The relative proportions of the active ingredient together with any carrier incorporating any physical property modifying components and the water may conveniently be adjusted within the above stated ranges such that the resistivity, viscosity and surface tension of the final composition is appropriate in order that a stable spray of appropriately-sized droplets for efficient dispersal of the active component is obtained.

Compounds of the invention may, in addition to the stated ingredients, include small amounts of ingredients which have no significant effects on the physical properties of the formulation. For example small amounts of preservative may optionally be included. In prior art compositions without added water, the presence of water as an impurity in the carrier or active agent may influence the physical properties (e.g. the viscosity, resistivity and/or the surface tension) of the composition in an unpredictable and undesirable manner. Hence, one advantage of the invention is that the presence of the specified amount of water in the composition dominates any influences from contaminant water or like polar compounds and therefore makes the properties of the composition more consistent.

A further advantage of the invention is that the presence of water or water and electrolyte may permit the flow rate of the spray to be attenuated if an active component of the composition has a particularly disadvantageous effect on the efficiency of dispersion of the composition, causing it to be sprayed at a rate which is inappropriately high because of, for example, its high potency as an active component, or for example, it is an expensive component as may be found in fine fragrances or pharmaceutical preparations, and fast spraying would result in a commercially undesirable product.

Other possible advantages embodied by the compositions of the invention include the fact that the compositions are less-flammable and have higher flash point than those that use solvents alone to adjust the physical properties, thus representing less of a fire risk (by contrast with prior art compositions which contain ethanol and/or low molecule weight hydrocarbons, or which contain a high proportion of 1-methoxy-2-propanpol) and do not need to be stored under pressure. The efficiency of dispersion of a composition may be determined qualitatively by examination of proximal deposition by visual inspection of the spray device and for the production of a fine plume of sprayed matter entrained into the local airflow.

Quantitative analysis of the efficiency of dispersion of a composition is possible through a range of means known to one skilled in the art. For example, the addition of a minimally- effective amount of a tracer component, for example a radioactive tracer, chemical tracer or more conveniently an optically-active tracer compound (such as Uvitex-OB, available from Ciba Speciality Chemicals PLC of Charter Way, Macclesfield, Cheshire, SK10 2NX, United Kingdom). Such a tracer component may be dissolved or uniformly suspended in the composition and the quality of the spray determined by, for example, observation of the spray and its trajectory under U.V. light. Quantification of chronic proximal deposition may be determined by swabbing the proximity of the electrostatic spray device and examination by methods appropriate to the type of tracer used (e.g. HPLC or spectrophotometry). Chronic mass loss may be determined by monitoring variation in weight.

Electrostatic spray devices employ an electric field to break up liquid by applying a potential difference between a spray electrode (into which the liquid is fed and ultimately exposed to the electric field), and a reference electrode somewhere in the vicinity. This type of spraying is well know in the art as described by Sir Geoffrey Taylor in the Proceedings of the Royal Society - 1964, pages 383-397. A device described in EP-A-1399265 provides a simple, robust spray electrode located near the outlet surface of the device, with another reference and discharging electrode in close proximity, also located near the device outlet surface. When configured in an open geometry, both electrodes are generally protected from user interference by sheltering inside separate recesses in the outlet surface. The outlet surface comprises a dielectric material, which is selected such that it leaks charge at a slow rate so that any charge deposited by way of ions or charged particles does not migrate or leak away immediately. This ensures that these dielectric recesses retain a slight charge of the same polarity as the electrodes they house. This significantly alters the local electric field shape and ensures that further deposition is discouraged - most significantly without the need for extra electrodes. A further advantage is that the device is polarity independent. In other words the spray electrode can be at any voltage (positive or negative) and the discharging electrode at any other voltage - provided only that the potential difference is sufficient to create the spray in the first instance. The range of workable potential differences depends on the distance between the two electrodes, the depth to which they are recessed from the outlet surface and the size of the recesses themselves, and potential differences can range from 1-2 kV, up to 30 kV or more, and can be both positive or negative in relative polarity.

The device of EP-A-1399265 is illustrated by reference to Figure 1, showing one possible embodiment, where a spray electrode 1 is housed inside a spray recess 2 and a discharging electrode 3 is housed inside a discharging recess 4. The spray electrode 1 in this example comprises a 27-gauge metal or conductive plastic capillary and the discharging electrode 3 comprises a sharp, stainless steel pin, 0.6 mm in diameter.

The two longitudinal axes of the cylindrical recess 2 and 4 are perpendicular to a spray outlet surface 5, which is manufactured from a dielectric material. In this example, the material is nylon and the spray outlet surface 5 is flat. However, other materials and curved surfaces can be used provided that there is sufficient charge retention at the spray outlet surface 5 to deflect the spray and charge carriers away from the device and electrodes.

Electrical connections are made via tapped holes 6 and 7, using conducting screws (not shown) which connect to a driving circuit. The liquid to be atomised is held in a threaded, glass vial 8 and air is fed into the glass vial 8 to replace the atomised liquid via the small air inlet hole 9.

When this device is energised by a driving circuit, liquid from the glass vial 8 is emitted from the spray electrode 1 in a very fine form, such that it quickly evaporates according to its vapour pressure and the ambient conditions in the vicinity of the device. An electrostatic spray device may be adapted to dispense a formulation according to the invention in an occasional manner or continuously. Dose rates may be, for example, up to 5g of formulation per day although such a level should not be seen as limiting. All amounts used herein are given in terms of w/w i.e. weight of component relative to total weight of composition.

The following examples illustrate the invention: Examples Exam le 1

Exam le 2

Example 3

Exam le 4

Exam le 5

Example 6

Example 7

Exam le 8

The compositions of Example 1-8 produced a stable spray with efficient dispersion of the active component without observable deposition when used with an electrostatic spray device as exemplified by the dispensing device disclosed in EP-A-1399265 for a continuous period of 1 day spraying continuously at a flow rate of around 5 g of formulation/day.

Exam le 9

The compositions of Example 9-11 produced a stable spray with efficient dispersion of the active component without observable deposition when used with an electrostatic spray device as exemplified by the dispensing device disclosed in EP-A-1399265 for a continuous period of 1 day spraying continuously at a flow rate of up to 5 g of formulation/day. In the case of Examples 1-11, proximal deposition was examined by visual inspection of the spray device for the presence of liquid visible under normal light conditions and for the production of a fine plume of sprayed matter entrained into the local airflow.

Example 12

Table 1 below compares the flash points of examples of the invention with control compositions. Amongst other benefits, the inclusion of small quantities of water in non-aqueous formulations may elevate the flash point of a composition. It is possible that such an elevation will move the composition into a new regulatory category whereby the movement restrictions or costs of transporting the composition are reduced or the labelling requirements for the composition are less onerous or the consumer packaging can avoid undesirable hazard labels.

Table 1

All references including patent and patent applications referred to in this application are incorporated herein by reference to the fullest extent possible.

Throughout the specification and the claims which follow, unless the context requires otherwise, the word 'comprise', and variations such as 'comprises' and 'comprising', will be understood to imply the inclusion of a stated integer or step or group of integers but not to the exclusion of any other integer or step or group of integers or steps.

Claims

WHAT IS CLAIMED IS:

I . A liquid electrostatic spray composition consisting of:

(i) a non-aqueous component which is substantially free of propellents and ethanol; and (ii) 0.1-25% w/w water component being water as adjuvant to modify the viscosity and/or resistivity and/or surface tension of the composition optionally together with additional electrolytes; the composition containing one or more active ingredients; and the composition having at 2O⁰C a resistivity in the range 1 x 10³ to 1 x 10⁶ Qm, a viscosity in the range 1 to 5 cP and a surface tension in the range 20-40 mN/m.

2. A composition according to claim 1 wherein the water content of the composition is 0.1- 15% w/w.

3. A composition according to claim 2 wherein the water content of the composition is 1 - 10% w/w.

4. A composition according to claim 3 wherein the water content of the composition is 2-6% w/w.

5. A composition according to any one of claims 1 to 4 wherein the water component contains minimal electrolyte.

6. A composition according to any one of claims 1 to 4 wherein the water component contains 0.001-2% w/w additional electrolyte based on weight of the water component.

7. A composition according to any one of claims 1 to 5 wherein the one or more active ingredients comprise a pest control agent.

8. A composition according to claim 7 wherein the pest control agent is selected from pyrethroid compounds, organic phosphorus compounds, carbamate compounds and synergists.

9. A composition according to claim 8 wherein the pest control agent is a pyrethroid compound.

10. A composition according to any one of claims 7 to 9 wherein the pest control agent is present at 0.1-15% by weight of composition.

I I . A composition according to any one of claims 7 to 9 consisting essentially of: 0.1 to 15% w/w pest control agent;

1-15% w/w water; and

70-98.9% w/w carrier.

12. A composition according to any one of claims 1 to 6 wherein the one or more active ingredients comprise a fragrance.

13. A composition according to claim 12 wherein the fragrance is a fragrance oil.

14. A composition according to claim 12 wherein the fragrance contains a component selected from 2,3 butanedione, 2,3 pentandione, 2,4-dimethylcyclohex-3-enyl- carboxaldedyde, 2-ethyl-3,5-dimethylpyrazine, 2-isobutyl-3-methoxypyrazine, 2- isopropyl-3-methoxypyrazine, 2-methyl-3-(isopropyl phenyl) propanal, 3-carboxymethyl- 2-pentylcylcopentane, 3-hydroxy-4,5-dimethyl-2-furanone, S-isocamphylcyclohexanol, 3- methyl-2-pentyl-2-cyclopentenone, 4-(4-hydroxy-4-methylpentyl)-3-cyclohexane, carboxyaldehyde, 4-acetoxy-3-pentyl tetrahydropyran, 4-hydroxy-2,5-dimethyl-3- furanone, 5-ethyl-3-hydroxy-4-methyl-2-furanone, 5-ethyl-4-hydroxy-2-methyl-3-furone, acetyl dedrene, aldehyde MNA, alpha-ionone, amyl salicylate, benzyl acetate, benzyl alcohol, benzyl benzoate, benzyl salicylate, butanol, camphor, cedryl methyl ether, cis-3- hexenol, citronellol, citronellyl nitrile, coumarin, damascenone, decanol, dimethyl benzyl carbinol, diphenyl oxide, ethanol, ethyl butyrate, ethyl malonate, ethyl-2-methyl butyrate, ethylene brassylate, eucalyptol, eugenol, geraniol, geranyl nitrile, gamma methyl ionone, greenyl acetate, guaiacol, habanolide, heliotropin, heptyl acetate, hexanal, hexanol, hexyl acetate, hexyl salicylate, hexyl-2-methyl butyrate, hexylcinnamaldehyde, hydroxy citronellal, indane, tetraline, isochroman musks, ionone, isoamyl alcohol, isobomyl acetate, iso butyl quinoline, isopentenyl acetate, lilialdehyde, limonene, linalool, menthol, methyl cedryl ketone, methyl dihydrojasmonate, methyl salicylate, myrcernol, nopol, octanol, OTNE, parmetol, phenethenol, phenoxylethylisobutrate, phenyl acetaldehyde diethyl acetal, prenyl acetate, p-tert-butylcyclohexyl acetate, styrallyl, terpinol, trans-2- hexanal, trans-2-hexenol, vanillin, vanoris, verdox, and vetiveryl acetate.

15. A composition according to any one of claims 12 to 14 wherein the fragrance is present at 1-99.9% w/w.

16. A composition according to claim 15 consisting essentially of: 10 to 99% w/w fragrance oil;

1-15% w/w water; and 0-89% w/w carrier.

17. A composition according to any one of claims 1 to 6 wherein the one or more active ingredients comprise a medicament.

18. A composition according to claim 17 wherein the medicament is selected from agents which are: diuretic, hypotensive, vasodilator or otherwise suitable for treating cardiac conditions, antibacterial, anti-viral, anti-fungal, suitable for treating bronchial, pulmonary or rhinal conditions, anti-histamine, anti-inflammatory, anti-depressant, anti-glaucoma, anti-spasmodic, anti-Parkinsonnian, anaesthetic, keratolyic, PDEV inhibitors, nicotinic receptor agonists and analgesics.

19. A composition according to any one of claims 17 to 18 wherein the medicament is present at 0.01-50% w/w.

20. A composition according to claim 19 consisting essentially of: 0.01 to 50% medicament; 1-15% water; and 35-98.99% carrier

21. A composition according to any one of claims 1 to 6 wherein the one or more active ingredients comprise an air sanitizer.

22. A composition according to any one of claims 1 to 21 wherein the carrier comprises a polyol.

23. A composition according to claim 22 wherein the polyol is a glycol methyl ether.

24. A composition according to claim 23 wherein the glycol methyl ether is selected from propylene glycol methyl ether and dipropylene glycol methyl ether.

25. A composition according to claim 24 wherein the glycol methyl ether is a mixture of propylene glycol methyl ether and dipropylene glycol methyl ether.

26. A composition according to claim 22 wherein the carrier is a mixture of propylene glycol methyl ether, dipropylene glycol methyl ether and isoparaffin.

27. A composition according to any one of claims 1 to 26 wherein the carrier includes a component which modifies the viscosity and/or resistivity and/or surface tension of the composition.

28. An electrostatic spray device reservoir containing a composition according to any one of claims 1 to 27.

29. An electrostatic spray device comprising a spray electrode into which the composition to be sprayed is fed from a reservoir, a reservoir according to claim 28 and a reference electrode in the vicinity of the spray electrode; such that upon application of electric potential across the electrodes the composition is sprayed from the spray electrode in the form of droplets.

30. Use of a composition according to any one of claims 1 to 27 in an electrostatic spray device.

31. A process for dispensing an active ingredient which comprises taking a composition according to any one of claims 1 to 27 and delivering it from an electrostatic spray device.