Abstract: To provide a chromium-free paint composition which can provide paint films which are excellent in terms of corrosion resistance on the edge surfaces, scratched surfaces and worked parts of a pre-coated steel sheet, and the paint films which can be obtained by coating this chromium-free paint composition. A chromium-free paint composition which includes paint film-forming resin (A), anti-rust pigment (B), comprising at least one type of amorphous MgO—V2O5-based compound, and crosslinking agent (C) which is characterized in that the mass content proportion of the aforementioned anti-rust pigment (B) is from 10 to 80 mass % with respect to the sum of the resin solid fraction mass of the aforementioned paint film-forming resin (A) and the aforementioned crosslinking agent (C), and the overall eluted ion content in a 10% aqueous solution of the aforementioned anti-rust pigment (B) is from 10 ppm to 100 ppm.

Abstract: Described is a paint composition comprising: a hydroxyl group-containing resin (A); a crosslinking agent (B), which reacts with hydroxyl groups; a radical copolymer (C); and an organosilica sol (D); wherein the radical copolymer (C): (a) has a monomer composition, with respect to the total mass of radically polymerizable monomer, of from 70.0 to 99.8 mass % unsaturated carboxylic acid amide, from 0.2 to 10 mass % radically polymerizable organosiloxane and from 0 to 29.8 mass % other radically polymerizable monomer, (b) is of weight average molecular weight from 1,500 to 15,000, and (c) has a hydroxyl group value of from 10 to 50 mgKOH/g, wherein the organosilica sol (D) is of average particle diameter from 1 to 30 nm, and wherein the solid fraction mass ratio represented by {(C) component+(D) component}/{(A) component+(B) component} is from 3 to 30% and the solid fraction mass ratio represented by {(C) component/(D) component} is from 0.2 to 5.0.

Abstract: Described is a paint composition comprising: a hydroxyl group-containing resin (A); a crosslinking agent (B), which reacts with hydroxyl groups; a radical copolymer (C); and an organosilica sol (D); wherein the radical copolymer (C): (a) has a monomer composition, with respect to the total mass of radically polymerizable monomer, of from 70.0 to 99.8 mass % unsaturated carboxylic acid amide, from 0.2 to 10 mass % radically polymerizable organosiloxane and from 0 to 29.8 mass % other radically polymerizable monomer, (b) is of weight average molecular weight from 1,500 to 15,000, and (c) has a hydroxyl group value of from 10 to 50 mgKOH/g, wherein the organosilica sol (D) is of average particle diameter from 1 to 30 nm, and wherein the solid fraction mass ratio represented by {(C) component+(D) component}/{(A) component+(B) component} is from 3 to 30% and the solid fraction mass ratio represented by {(C) component/(D) component} is from 0.2 to 5.0.

Abstract: To provide a chromium-free paint composition which can provide paint films which are excellent in terms of corrosion resistance on the edge surfaces, scratched surfaces and worked parts of a pre-coated steel sheet, and the paint films which can be obtained by coating this chromium-free paint composition. A chromium-free paint composition which includes paint film-forming resin (A), anti-rust pigment (B), comprising at least one type of amorphous MgO—V2O5-based compound, and crosslinking agent (C) which is characterized in that the mass content proportion of the aforementioned anti-rust pigment (B) is from 10 to 80 mass % with respect to the sum of the resin solid fraction mass of the aforementioned paint film-forming resin (A) and the aforementioned crosslinking agent (C), and the overall eluted ion content in a 10% aqueous solution of the aforementioned anti-rust pigment (B) is from 10 ppm to 100 ppm.