Aqueous dispersion of cationic advanced diglycidyl ether blend

A coating composition suitable for electrodeposition comprising

• (I) an aqueous dispersion of an advanced epoxy cationic resin prepared from an epoxy resin composition having terminal oxirane groups which includes the step of converting oxirane groups to cationic groups by reacting a nucleophile with at least some of the oxirane groups of the epoxy resin composition wherein an organic acid and water are added during some part of this conversion;
• wherein said epoxy resin composition is a blend of
• (A) an advanced epoxy resin obtained by reacting in the presence of a suitable catalyst
• (1) a composition comprising
• (a) from about 20 to 100 weight percent of a diglycidylether of an aliphatic diol essentially free of ether oxygen atoms;
• and
• (b) from zero to about 80 weight percent of a diglycidylether of a dihydric phenol;
• and
• (2) at least one dihydric phenol wherein components (1) and (2) are employed in such quantities that the resultant epoxide equivalent weight is from about 350 to about 10,000, and
• a different epoxy-based resin wherein at some time during preparation of the composition, the resins are converted to cationic resins whereby there is obtained a blend of a cationic, advanced epoxy resin and a different cationic epoxy-based resin;
• said blend containing from about 10 to about 90 percent of (A) and from about 90 to about 10 percent of (B) based on the total weight of cationic resin and having a charge density of from about 0.2 to about 0.6 milliequivalent of charge per gram of resin;
• in combination with
• (II) curing agent selected from a blocked polyisocyanate, an amine aldehyde resin, and a phenol aldehyde resin.