Binder compositions for direct-to-metal coatings

An aqueous coating composition comprising an aqueous emulsion copolymer, said copolymer comprising as polymerized units:

• (a) one or more ethylenically unsaturated monomers or salts thereof, and (b) one or more ethylenically unsaturated acid monomers or salts thereof comprising
• at least one strong acid monomer or salt thereof;
• wherein (b) is less than six percent (6%) by weight of the copolymer and the strong acid monomer or salt thereof is greater than forty five percent (45%) by weight of the total amount in (b) up to a maximum of 3.7% by weight of the copolymer;
• and
• wherein the aqueous coating composition exhibits a gloss rating of at least 73 at 60 degrees according to ASTM D-523 when coated onto a substrate.

A method of obtaining corrosion resistance on a metal substrate of either no greater than 20% rust or a blister rating no greater than “M” after at least 7 days of exposure to salt spray according to ASTM B-117-97 comprising:

• (i) coating said substrate with an aqueous coating composition comprising an aqueous emulsion copolymer, said copolymer comprising as polymerized units:
• (a) one or more ethylenically unsaturated monomers or salts thereof;
• and
• (b) one or more ethylenically unsaturated acid monomers or salts thereof, comprising at least one strong acid monomer or salt thereof;
• wherein (b) is less than six percent (6%) by weight of the copolymer and the strong acid monomer or salt thereof is greater than forty five percent (45%) by weight of the total amount in (b) up to a maximum of 3.7% by weight of the copolymer;
• and
• (ii) drying or allowing to dry the aqueous coating substrate.

A method of obtaining a gloss rating on a metal substrate of at least 73 at 60 degrees according to ASTM D-523 comprising:

• (i) coating said substrate with an aqueous coating composition comprising an aqueous emulsion copolymer, said copolymer comprising as polymerized units:
• (a) one or more ethylenically unsaturated monomers or salts thereof, and
• (b) one or more ethylenically unsaturated acid monomers or salts thereof, comprising at least one strong acid monomer or salt thereof;
• wherein (b) is less than six percent (6%) by weight of the copolymer and the strong acid monomer or salt thereof is greater than forty five percent (45%) by weight of the total amount in (b) up to a maximum of 3.7% by weight of the copolymer;
• and
• (ii) drying or allowing to dry the aqueous coating substrate.