Patent GB-1122044-A (GB)
Title: Coating compositions for electrostatic spraying
IPC: C09D7/63
Filed: 1966-06-13
Abstract: Coating compositions for electrostatic spraying comprise a solution of a film-forming material in an organic solvent and, dissolved therein, 0.0005-0.02% by weight of a mixture of (a) an alkaline earth metal or aluminium salt of an organic acid, said salt having a molecular weight \sF200 and (b) a material having a molecular weight \sF200 of which the product of the molecular weight and specific conductivity at 25 DEG  C. of a solution of 1 gm. in 1 litre of benzene is at least 10-10, (b), if a salt, having both a different cation and a different anion from (a), and the weight ratio (a): (b) being 1:50 to 50:1. Salt (a) may be a salt of a carboxylic or sulphonic acid, of a phenol, of an alkyl phenol formaldehyde condensate, or of a sulphonated dialkyl ester of an aliphatic dicarboxylic acid, particularly the Ca, Mg or Al salt of oleic, or diisopropyl salicylic acid, Ca phenyl stearate, or the Ca or Al salt of the sulphonated dioctyl ester of succinic acid; a calcium salt is preferred. Material (b), which must have neither the same anion nor cation as (a), may also be chosen from the alkaline earth metal or Al salts of organic acids, or it may be an alkali metal or ammonium organic acid salt, a quaternary ammonium, phosphonium or sulphonium salt, a sulphone, sulphonamide, polyalkylene oxide, phenolformaldehyde condensate, alcohol, ether, ester, oxidized mineral oil, phosphatide, or asphaltene. In an example 5-15 c.c. of a solution containing 1% by weight each of aluminium di-isopropyl salicylic acid and calcium dodecyl sulphosuccinate in xylene is added to a conventional alkyd base enamel having the composition 16.3% TiO2 (anatase), 19.4% TiO2 (rutile), 10.2% silicate extender, 15.0% xylene, 15.4% toluene and 23.7% soya-safflower alkyd resin containing the two oils in 50:50 weight ratio, the oil component being present in medium length to provide a pure alkyd in which the molar ratio of glycerol to phthalic anhydride is 1.5:1.ALSO:Coating compositions for electrostatic spraying comprise a solution of a film-forming material in an organic solvent and, dissolved therein, 0.0005-0.02% by weight of a mixture of (a) an alkaline earth metal or aluminium salt of an organic acid, said salt having a molecular weight \sF200 and (b) a material having a molecular weight \sF200 of which the product of the molecular weight and specific conductivity at 25 DEG  C. of a solution of 1 gm. in 1 litre of benzene is at least 10-10, (b), if a salt, having both a different cation and a different anion from (a), and the weight ratio (a):(b) being 1:50 to 50:1.  Salt (a) may be a salt of a carboxylic or sulphonic acid, of a phenol, of an alkyl phenol-formaldehyde condensate, or of a sulphonated dialkyl ester of an aliphatic dicarboxylic acid, particularly the Ca, Mg or Al salt of oleic or di-isopropyl salicylic acid, Ca phenyl stearate, or the Ca or Al salt of the sulphonated dioctyl ester of succinic acid; a calcium salt is preferred.  Material (b), which must not have the same anion or cation as (a), may be also chosen from the alkali organic earth metal or aluminium salts of organic acids, or it may be an alkali metal or ammonium organic acid salt, a quaternary ammonium, phosphonium or sulphonium salt, a sulphone, sulphonamide, polyoxyalkylene oxide, phenol-formaldehyde condensate, alcohol, ether, ester, oxidized mineral oil, phosphatide or asphaltene, particularly tetraisoamyl ammonium picrate, ammonium di-isopropyl salicylate, calcium oleate, petroleum sulphonic acid or Na sulphonate, lithium dioctyl sulphosuccinate or cetyl pyridinium bromide.  The film-former, preferably with a dielectric constant less than 7, may be a wax or bodied linseed oil, as well as a number of synthetic resins, and preferably constitutes at least 15% by weight of the composition. The solvent is preferably non-polar and may be mineral spirits, benzene,toluene or xylene.