Electrocoating composition containing styrene-maleic anhydride copolymer and epoxy ester resin exhibiting high throwing power

Claim 1

A COMPOSITION SUITABLE FOR ELECTROCOATING AN ELECTRICALLY CONDUCTIVE SUBSTRATE IN AN AQUEOUS MEDIUM USING HIGH VOLTAGES AND CHARACTERIZED BY EXHIBITING HIGH THROWING POWER AND CROSSLINKABLE BY OXYGEN PROMOTED RADICAL GRAFT POLYMERIZATION COMPRISING: A. A PARTIAL ESTER OF STYEENE MALEIC ANHYDRIDE COPOLYMER RESIN ESTERFIED TO ABOUT 25 TO 125 PER CENT HALF-ESTER WITH A SATURATED OR OLEFINICALLY UNSATURATED ALKANOL OF 12 TO 30 CARBON ATOMS SAID STYRENE-MALEIC ANHYDRIDE COPOLYMER HAVING A MOLE RATIO OF STYRENE TO MALEIC ANHYDRIDE OF ABOUT 1:1 TO 4:1 AND A MOLECULAR WEIGHT OF ABOUT 500 TO 4000, SAID PARTIAL ESTER OF SAID COPOLYMER HAVING AN ACID NUMBER IN THE RANGE OF ABOUT 20 TO 350 AND NEUTRALIZED TO AN EXTENT OF 20 TO 120 PER CENT BASED ON SAID ACID NUMBER OF SAID PARTIAL ESTER COPOLYMER WITH A NEUTRALIZATION AGENT SELECTED FROM THE GROUP CONSISTING OF AMMONIA, LOWER ALIPHATIC AMINES, LOWER ALKANOL AMINES AND ALKALI METAL HYDROXIDES AND B. A CARBOXYL FUNCTIONAL EPOXY RESIN ESTERFIED WITH AN OLEFINICALLY UNSATURATED FATTY ACID, SAID OLEFINICALLY UNSATURATED FATTY ACID BEING DERIVED FROM A SEMI-DRYING OIL OR DRYING OIL HAVING AN IODINE VALUE OF GREATER THEN 90, SAID CARBOXYL FUNCTIONALITY BEING PROVIDED BY EITHER (1) HALF ACID ESTER FORMATION BETWEEN RESIDUAL HYDROXYL GROUP OF THE EPOXY ESTER RESIN AND A DICARBOXYLIC ACID ANHYDRIDE, OR (2) BY REACTION OF MALEIC ANHYDRIDE WITH OLEFINIC SITES ON THE UNSATURATED FATTY ACID MOIETIES OF SAID ESTERIFIED EPOXY RESIN, SAID EPOXY ESTER PROVIDED WITH CARBOXYL FUNCTIONALITY HAVING AN ACID NUMBER IN THE RANGE OF FROM 40 TO 80 AND NEUTRALIZED TO THE EXTENT OF 20 TO 120 PER CENT BASED ON SAID ACID NUMBER OF SAID RESIN WITH A NEUTRALIZATION AGENT SELECTED FROM THE GROUPS CONSISTING OF AMMONIA, A LOWER ALIPHATIC AMINE, A LOWER ALKANOL AMINE AND AN ALKALI METAL HYDROXIDE WHEREIN SAID EPOXY RESIN IS IN THE RANGE OF FROM 30 TO 300 WEIGHT PER CENT OF SAID ESTERIFIED COPOLYMER AND WHEREIN SAID ESTERIFIED COPOLYMER AND SAID EPOXY RESIN RANGE IN AMOUNT FROM 5 TO 30 WEIGHT PER CENT OF SAID AQUEOUS MEDIUM.