Resin dispersion for cationic electrodeposition and low temperature curable cationic electrodeposition coating composition including the same

A method of preparing a resin dispersion of a cationic electrodeposition comprising the steps of:

• preparing a cationic electrodeposition resin in the presence of an organic solvent from (a) about 40-60% by weight of a cationic electrodeposition synthetic resin produced by an epoxy-amino addition reaction.(b) about 5-10% by weight of an acrylic cationic electrodeposition resin having an amino group (c) about 1-3% by weight of a fatty acid ester resin synthesized by an esterification reaction of styrene-allylalcohol copolymer and fatty acid and (d) about 30-50% by weight of polyurethane cross-linking agent produced from a mixture of blocked polymethylene polyphenyl polyisocyanate and blocked isophorone diisocyanate;
• preparing an aqueous dispersion by mixing about 35-45 parts by weight of said cationic electrodeposition resin, about 55-65 parts by weight of deionized water, about 0.3-1.5 parts by weight of an acid for a neutralization, about 1-5 parts by weight of a reaction product of manganese phosphate and an acid diluted to a concentration of 10% in deionized water and about 0.5-1 parts by weight of a cationic surfactant;
• and
• removing organic solvents having a low boiling point from said aqueous dispersion by extracting and then filtering.

A cationic electrodeposition coating composition comprising an aqueous dispersion and a pigment paste composition, said aqueous dispersion being prepared by mixing:

• about 35-45 parts by weight of a cationic electrodeposition resin prepared in the presence of an organic solvent from (a) about 40-60% by weight of a cationic electrodeposition synthetic resin produced by an epoxy-amino addition reaction (b) about 5-10% by weight of an acrylic cationic electrodeposition resin having an amino group (c) about 1-3% by weight of a fatty acid ester resin synthesized by an esterification reaction of styrene-allylalcohol copolymer and fatty acid and (d) about 30-50% by weight of polyurethane cross-linking agent produced from a mixture of blocked polymethylene polyphenyl polyisocyanate and blocked isophorone diisocyanate;
• about 55-65 parts by weight of deionized water;
• about 0.3-1.5 parts by weight of an acid for a neutralization;
• about 1-5 parts by weight of a reaction product of manganese phosphate and an acid diluted to a concentration of 10% in deionized water;
• and
• about 0.5-1 parts by weight of a cationic surfactant.

A method of preparing a cationic electrodeposition coating composition comprising the steps of:

• preparing a cationic electrodeposition resin in the presence of an organic solvent from (a) about 40-60% by weight of a cationic electrodeposition synthetic resin produced by an epoxy-amino addition reaction (b) about 5-10% by weight of an acrylic cationic electrodeposition resin having an amino group (c) about 1-3% by weight of a fatty acid ester resin synthesized by an esterification reaction of styrene-allylalcohol copolymer and fatty acid and (d) about 30-50% by weight of polyurethane cross-linking agent produced from a mixture of blocked polymethylene polyphenyl polyisocyanate and blocked isophorone diisocyanate;
• air preparing an aqueous dispersion by mixing about 35-45 parts by weight of said cationic electrodeposition resin, about 55-65 parts by weight of deionized water, about 0.3-1.5 parts by weight of an acid for a neutralization, about 1-5 parts by weight of a reaction product of manganese phosphate and an acid diluted to a concentration of 10% in deionized water, and about 0.5-1 parts by weight of a cationic surfactant;
• preparing a cationic electrodeposition resin dispersion by removing organic solvents having a low boiling point from said aqueous dispersion by extracting and then filtering;
• and
• mixing said resin dispersion of a cationic electrodeposition and a pigment paste composition.