Process for electrocoating aqueous coating composition comprising dispersion in water of ionizable salt of epoxy amine adduct

Claim 1

A method of depositing a coating composition on an electrically conductive substrate which comprises immersing said article in an aqueous coating composition consisting essentially of a dispersion in water of an ionizable salt of an epoxy-amine adduct and an acid together with a crosslinking agent for the adduct, characterized in that the ionizable salt consists of the combination of an acid and an epoxy-amine adduct selected from the compounds of the formulae B.sub.1 -- A.sub.1 -- C.sub.1 -- A.sub.2 -- B.sub.2 (a) and B.sub.1 -- A.sub.1 -- C.sub.1 -- A.sub.2 C.sub.2 -- A.sub.3 -- B.sub.2 (b) wherein A 1 , a 2 and A 3 are epoxy free residues of essentially straight-chain di-epoxides; B 1 and B 2 and residues of primary or secondary mono-amines which have a pK b value of 4 maximum; C 1 and C 2 are residues of amines having one or two primary amino groups; and further characterized in that: (1) the acid shall have a pK a value of from 1.5-6.0, and if it is a carboxylic acid it shall contain not more than two carboxyl groups; (2) at least 40% of the amine groups must be reacted with the acid, to form an amine salt; and (3) the epoxy-amine adduct shall have a molecular weight of 1500 - 7000; making said substrate the cathode and passing electrical current between said substrate and a counter-electrode which is in electrical contact with said aqueous coating composition.

Claim 2

A method of depositing a coating composition on an electrically conductive substrate which comprises immersing said article in an aqueous coating composition consisting essentially of a dispersion in water of an ionizable salt of an epoxy-amine adduct and an acid together with a crosslinking agent for the adduct, characterized in that the ionizable salt consists of the combination of an acid and an epoxy-amine adduct selected from the compounds of the formulae B.sub.1 -- A.sub.1 -- C.sub.1 -- A.sub.2 -- B.sub.2 (a) and B.sub.1 -- A.sub.1 -- C.sub.1 -- A.sub.2 C.sub.2 -- A.sub.3 -- B.sub.2 (b) wherein A 1 , a 2 and A 3 are epoxy free residues of essentially straight-chain di-epoxides; B 1 and B 2 and residues of primary or secondary mono-amines which have a pK b value of 4 maximum; C 1 and C 2 are residues of amines having one or two primary amino groups; and further characterized in that: (1) the acid shall have a pK a value of from 1.5-6.0, and if it is a carboxylic acid it shall contain not more than two carboxyl groups; (2) at least 40% of the amine groups must be reacted with the acid, to form an amine salt; and (3) the epoxy-amine adduct shall have a molecular weight of 1500 - 7000; making said substrate the cathode and passing electrical current between said substrate and a counter-electrode which is in electrical contact with said aqueous coating composition.