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.

1 . An aerosol spray device which contains an electrically neutral composition in a 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 a formulation of the composition and a material of a portion of the aerosol spray device with which the emulsion comes into contact on spraying are selected such that at least one of the following is true: 
 i) a difference in the surface energies between a Lewis base component of the emulsion and a Lewis base component of the material with which the emulsion comes into contact on spraying is at about 2 mJ m 2 ; and    ii) a difference in the surface energies between a Lewis acid component of the emulsion and a Lewis acid component of the material with which the emulsion comes into contact on spraying is at least about 0.5 mJ m −2 .    
   
   
       2 . The aerosol spray device as claimed in  claim 1 , wherein at least one of the following is true: the difference in i) is at least about 5 mJ m −2  and the difference in ii) is at least about 1 mJ m −2 .  
   
   
       3 . The aerosol spray device as claimed in  claim 2 , wherein at least one of the following is true: the difference in i) is at least about 15 mJ m −2  and the difference in ii) is at least about 2 mJ m −2 .  
   
   
       4 . The aerosol spray device as claimed in  claim 1 , wherein the composition contained therein comprises: 
 (a) at least one propellant in an amount of about 2 to about 80% w/w;    (b) at least one non-ionic surfactant in an amount of about 0.01 to about 10% w/w, said surfactant being selected from the group consisting of: mono-, di- and tri-sorbitan esters; polyoxyethylene mono-, di- and tri-sorbitan esters; mono- and poly-glyceryl esters; alkoxylated alcohols; alkoxylated amines; alkoxylated acids; amine oxides; ethoxylated/proproxylated block copolymers; alkoxylated alkanolamides; and alkoxylated alkyl phenols,    (c) optionally at least one solvent within an oil phase of the emulsion in an amount up to about 80% w/w, said solvent being selected from the group consisting of n-paraffins, iso-paraffins and naphthenes;    (d) at least one component selected from the group consisting of polar and aromatic compounds, in an amount of about 0.01 to 80% w/w based on the non-ionic surfactant, said component being selected from the group consisting of 
 (I) alkali metal salts, alkaline earth metal salts, ammonium salts, amine salts or amino alcohol salts of at least one of the compounds selected from the group consisting of alkyl sulphates, alkyl ether sulphates, alkylamidoether sulphates, alkylarylpolyether sulphates, monoglyceride sulphates, polyglyceride sulphates, alkyl sulphonates, alkylamine sulphonates, alkyl-aryl sulphonates, olefin sulphonates, paraffin sulphonates, alkyl sulphosuccinates, alkylether sulphosuccinates, alkylamide sulphosuccinates, alkyl sulphocinnamates, alkyl sulphoacetates, alkyl phosphates, alkylether phosphates, acyl sarcosinates, acyl isothionates and N-acyl taurates,  
 (II) alkylamidopropylbetaines, alkylamidobetaines, alkylamidosulphobetaines, alkylbetaines, aminimides, quaternary ammonium compounds, quaternary phosphonium compounds,  
 (III) carboxylic acids, carboxylic acid salts, esters, ketones, aldehydes, amides or amines of carboxylic acids containing from 6 to 30 carbon atoms, and  
 (IV) diethyl orthophthalate, methylphenylcarbinyl acetate, α-methyl ionone, 4-hydroxy-3-methoxy-benzaldehyde, phenylethyl alcohol, dipropylene glycol, styryl acetate, n-butyl benzoate, isopropyl-4-hydroxybenzoate, isobutyl acetophenone, isopropyl acetophenone, nicotinic acid, benzoic acid, 2-naphthol, neopentyl benzene, naphthalene, toluene, fullerene, tannic acid, t-butylacetophenone, isopropylcinnamate, resorcinol, 4-methoxycinnamaldehyde, arbutin, 4-acetoxy-3-methoxycinnamaldehyde, 4-isopropylphenol, trans-stilbene, esculetin, p-chloro-m-xylenol, chloro-o-cresol, triclosan, norfenefrine, norepinephrine, hexyl-resorcinol, limonene, methylphenylcarbinyl acetate and p-tert-butyl-α-methylhydrocinnamic aldehyde,  
 in an amount such that a theoretical conductivity of the emulsion is less than a bulk conductivity of the emulsion; and  
   (e) water.    
   
   
       5 . The aerosol spray device as claimed in  claim 4  wherein component (d) is selected from the group consisting of 
 (II) alkylamidopropylbetaines, alkylamidobetaines, alkylamidosulphobetaines, alkylbetaines, aminimides, quaternary ammonium compounds, quaternary phosphonium compounds; and    (III) carboxylic acids, carboxylic acid salts, esters, ketones, aldehydes, amides or amines of carboxylic acids containing from 6 to 30 carbon atoms.    
   
   
       6 . The aerosol spray device as claimed in  claim 4  wherein, in the composition, the solvent is present and is selected from the group consisting of n-paraffins and iso-paraffins.  
   
   
       7 . The aerosol spray device as claimed in  claim 6  wherein the solvent is present in an amount up to 40% w/w.  
   
   
       8 . The aerosol spray device as claimed in  claim 4  wherein, in the composition, the difference between the theoretical conductivity and the bulk conductivity of the emulsion is at least about 5μ5 cm −1 .  
   
   
       9 . The aerosol spray device as claimed in  claim 4  wherein, in the composition, the amount of non-ionic surfactant is from 0.01 to 10%.  
   
   
       10 . The aerosol spray device as claimed in  claim 9  wherein, in the composition, the amount of component (d) is from 0.01 to 30% w/w/ based on the non-ionic surfactant.  
   
   
       11 . The aerosol spray device as claimed in  claim 10  wherein the amount of component (d) is from 0.1 to 10% based on the non-ionic surfactant.