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  Electrostatic aerosol compositionsUSPTO Application #: 20070093558Title: Electrostatic aerosol compositions Abstract: An electrically neutral composition in the form of a water-in-oil or an oil-in-water emulsion is imparted with a unipolar electrostatic charge on spraying from an aerosol spray device by incorporating into the composition a non-ionic surfactant and at least one polar or ionic or aromatic or linearly conjugated compound. The amount of the polar or ionic or aromatic or linearly conjugated compound included in the composition is about 0.01 to about 80% w/w based on the non-ionic surfactant, but is such that the theoretical conductivity of the emulsion is less than the bulk conductivity of the emulsion. (end of abstract)
Agent: Fish & Richardson PC - Minneapolis, MN, US Inventors: Duncan Roger Harper, Neale Harrison, John Douglas Morgan, John Howard Clint, Mario Abela USPTO Applicaton #: 20070093558 - Class: 516008100 (USPTO) Related Patent Categories: Colloid Systems And Wetting Agents; Subcombinations Thereof; Processes Of, Continuous Gas Or Vapor Phase: Colloid Systems; Compositions Containing An Agent For Making Or Stabilizing Colloid Systems; Processes Of Making Or Stabilizing Colloid Systems; Processes Of Preparing The Compositions (e.g., Smoke, Fog, Aerosol, Cloud, Mist), Discontinuous Phase Primarily Liquid (e.g., Mist, Fog), The Continuous Phase Contains A Propellant Derived From Non-gaseous Phase (e.g., Liquified Propellant, Such As Hydrocarbon, Halogenated Hydrocarbon, Dimethylether; Sorbed Or Dissolved Co2), Precursor Contains Plural Immiscible Liquid Phases (e.g., Emulsion) The Patent Description & Claims data below is from USPTO Patent Application 20070093558. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a division of U.S. application Ser. No. 10/091,284 filed Mar. 5, 2002, which is a continuation of International Application No. PCT/GB00/03426, filed Sep. 5, 2000, published in the English language on Mar. 15, 2001, under International Publication No. WO 01/18145 A2, which claims priority of British Application No. 9921037.0 filed on Sep. 7, 1999. The disclosures of these earlier applications are incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] The present invention relates to aerosol compositions and, in particular, compositions in which the droplets are imparted with an electrostatic charge on spraying from an aerosol spray device and in which the electrostatic charge on the droplets is maximized through the inclusion in the compositions of certain selected components. [0003] Aerosol spray devices are a convenient form in which a variety of useful products, such as insecticides, air fresheners, antiperspirants, hair sprays, horticultural products, waxes and polishes, oven cleaners, starches and fabric finishes, shoe and leather care products, glass cleaners and various other household, institutional, professional or industrial products, can be dispensed. [0004] The utility of aerosol spray devices resides in the ability to readily deliver the composition contained within the device in the form of fine droplets to the target area, for example the spraying of an insecticide onto target insects. [0005] In International Patent Publication No. WO 97/28883 there is described a method of precipitating airborne particles from air in a domestic environment containing such particles in which the air to be treated is sprayed with liquid droplets from an aerosol spray device with a unipolar charge being imparted to the droplets during the spraying of the liquid droplets by the aerosol spray device, the unipolar charge being at a level such that the droplets have a charge to mass ratio of at least +/-1.times.10.sup.-4 C/kg. [0006] In International Patent Publication No. WO 99/01227 there is described a method of killing flying insects by spraying into the air in which the insects are flying liquid droplets of an insecticidal composition, a unipolar charge being imparted to the liquid droplets by double layer charging and charge separation during spraying, the unipolar charge being at a level such that the said liquid droplets have a charge to mass ratio of at least +/-1.times.10.sup.-4 C/kg. An apparatus for imparting the unipolar charge of this magnitude to a liquid composition is also described. BRIEF SUMMARY OF THE INVENTION [0007] We have now found that by careful selection of the components which are to be contained within a liquid composition for application by aerosol spraying, it is possible to charge the liquid droplets during the spraying operation without requiring any special features of the construction of the aerosol spraying head. [0008] Accordingly, in one aspect the present invention provides an electrically neutral composition in the form of a water-in-oil or an oil-in-water emulsion, in which droplets of the emulsion on discharge from an aerosol spray device are imparted with a unipolar electrostatic charge, which composition comprises: [0009] (a) at least one propellant in an amount of about 2 to about 80% w/w; [0010] (b) at least one non-ionic surfactant in an amount of about 0.01 to about 10% w/w; [0011] (c) optionally one or more oils or solvents, preferably aliphatic, linearly conjugated or aromatic, within the oil phase of the emulsion in an amount of up to about 80% w/w, preferably up to about 40% w/w; [0012] (d) at least one polar or ionic or aromatic or conjugated compound in an amount of about 0.01 to 80% w/w based on the non-ionic surfactant, but which is such that the theoretical conductivity of the emulsion is less than the bulk conductivity of the emulsion; and [0013] (e) water. [0014] In a second aspect the present invention provides a method of enhancing the unipolar charge which is imparted to droplets of an emulsion on discharge from an aerosol spray device in which the droplets are formed from an oil-in-water or a water-in-oil emulsion composition which comprises: [0015] (a) at least one propellant in an amount of about 2 to about 80% w/w; [0016] (b) at least one non-ionic surfactant in an amount of about 0.01 to about 10% w/w; [0017] (c) optionally one or more oils or solvents, preferably aliphatic, linearly conjugated or aromatic, within the oil phase of the emulsion in an amount of up to about 80% w/w, preferably up to about 40% w/w; [0018] (d) at least one polar or ionic or aromatic or linearly conjugated compound in an amount of about 0.1 to about 80% w/w based on the non-ionic surfactant, but which is such that the theoretical conductivity of the emulsion is less than the bulk conductivity of the emulsion; and [0019] (e) water. [0020] In a third aspect the present invention provides the use of a non-ionic surfactant and at least one polar or ionic or aromatic or conjugated compound in an amount of about 0.01 to about 80% w/w based on the non-ionic surfactant to enhance the electrostatic charge imparted to droplets of a composition in the form of a water-in-oil or an oil-in-water emulsion on discharge from an aerosol spray device, which composition includes: [0021] (a) at least one propellant in an amount of about 2 to about 80% w/w; [0022] (b) optionally one or more oils or solvents, preferably aliphatic, linearly conjugated or aromatic, within the oil phase in an amount of up to about 80% w/w, preferably up to about 40% w/w; and [0023] (c) water; and the amount of the polar or ionic or aromatic or conjugated compound being such that the theoretical conductivity of the emulsion is less than the bulk conductivity of the emulsion. [0024] In a fourth aspect the present invention provides an aerosol spray which contains an electrically neutral composition in the form of a water-in-oil emulsion, an oil-in-water emulsion or a single phase composition, in which liquid droplets of the composition on discharge from the aerosol spray device are imparted with a unipolar electrostatic charge, wherein the formulation of the composition and the material of the portion of the aerosol spray device with which the liquid comes into contact on spraying are selected such that [0025] i) the difference in surface energies between the Lewis base component of the liquid and the Lewis base component of the material with which the liquid comes into contact on spraying is at least about 2 mJ m.sup.-2; and/or [0026] ii) the difference in surface energies between the Lewis acid component of the liquid and the Lewis acid component of the material with which the liquid comes into contact on spraying is at least about 0.5 mJ m.sup.-2. [0027] The liquid droplets preferably have a charge to mass ratio of at least about +/-1.times.10.sup.-4 C/kg, more preferably at least about +/-2.times.10.sup.-4 C/kg. The higher the charge to mass ratio of the liquid droplets, the more effective the liquid droplets will be for their intended use, such as precipitating airborne particles and targeting insects. This charge level is considerably higher than the charge level which is achieved when spraying conventional liquid formulations from conventional aerosol spray devices, where charge levels are obtained of the order of about +/-1.times.10.sup.-5 to about +/-1.times.10.sup.-8 C/kg [0028] In the formulations of the present invention it is the combination of components (b) and (d) of the emulsion which improves the electron transfer through the emulsion with the charge being transferred from droplet to droplet through the emulsion at the interface between the disperse phase and the continuous phase. Preferably, at least about 90% by volume of the droplets of the disperse phase within the emulsion have an average diameter of less than about 60 .mu.m, and more preferably in a range of about 20 to about 40 .mu.m. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS [0029] The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings a measuring embodiment which is presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings: [0030] FIG. 1-a is a plan view of a valve insert of a standard aerosol can used to measure the charge to mass ratio of the compositions of the invention; [0031] FIG. 1-b is a sectional view of the valve insert of FIG. 1-a; and [0032] FIG. 1-c is an inverted plan view of the valve insert of FIG. 1-a. DETAILED DESCRIPTION OF THE INVENTION [0033] The various components (a) to (e) of the compositions of the present invention are discussed in turn below. Continue reading... Full patent description for Electrostatic aerosol compositions Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Electrostatic aerosol compositions patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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