Surface-treated metal material and process for producing the same

1. A surface-treated metal material, comprising:

a metal material, and a coating film disposed on the surface thereof,

the coating film containing (A) an organic resin having a glass transition temperature of more than 35° C. and not more than 100° C., and (B) an organic resin having a glass transition temperature of more than 100° C. and not more than 250° C.,

wherein the difference between the glass transition temperatures of the organic resins (A) and (B) is 50° C. or more, and

wherein the coating film has a tensile strength at 20° C. of 15 N/mm 2 or more, and

wherein the coating film further contains (C) silica, (E) a phosphoric acid compound and (F) a lubricity imparting agent, and

wherein the coating film further contains a crosslinked structure formed between (D) at least one crosslinking agent selected from a silane coupling agent, a carbodiimide compound, an epoxy compound, an organic titanate compound and a melamine resin, and at least one member selected from the organic resin (A), the organic resin (B) and the silica (C).

2. The surface-treated metal material according to claim 1 , wherein the glass transition temperature of the organic resin (A) is more than 50° C. and not more than 100° C.

3. The surface-treated metal material according to claim 1 , wherein the glass transition temperature of the organic resin (B) is more than 150° C. to not more than 250° C.

4. The surface-treated metal material according to claim 1 , wherein the organic resins (A) and (B) contain an anionic functional group.

5. The surface-treated metal material according to claim 1 , wherein the organic resin (A) is a polyolefin resin or a polyurethane resin.

6. The surface-treated metal material according to claim 1 , wherein the organic resin (B) is a polyurethane resin.

7. The surface-treated metal material according to claim 1 , wherein a mixed resin of the organic resins (A) and (B) has a tensile strength at 20° C. of 20 N/mm 2 or more and a total elongation at 20° C. of 20% or more.

8. The surface-treated metal material according to claim 1 , wherein the coating film contains a siloxane bond or a chemical bond formed between a silanol group and another functional group.

9. A process for producing a surface-treated metal material, comprising coating a surface of a metal material with an aqueous coating material containing (A′) an aqueous organic resin having a glass transition temperature of more than 35° C. to not more than 100° C. and (B′) an aqueous organic resin having a glass transition temperature of more than 100° C. to not more than 250° C., so that the difference between the glass transition temperatures of the aqueous organic resins (A′) and (B′) being 50° C. or more, and then drying the coating by heating to thereby form a coating film, and

wherein the coating film has a tensile strength at 20° C. of 15 N/mm 2 or more, and

wherein the coating film further contains (C) silica, (E) a phosphoric acid compound and (F) a lubricity imparting agent, and

wherein the coating film further contains a crosslinked structure formed between (D) at least one crosslinking agent selected from a silane coupling agent, a carbodiimide compound, an epoxy compound, an organic titanate compound and a melamine resin, and at least one member selected from the organic resin (A′), the organic resin (B′) and the silica (C).

10. The process for producing a surface-treated metal material according to claim 9 , wherein the glass transition temperature of the aqueous organic resin (A′) is more than 50° C. to not more than 100° C.

11. The process for producing a surface-treated metal material according to claim 9 , wherein the glass transition temperature of the aqueous organic resin (B′) is more than 150° C. to not more than 250° C.

12. The process for producing a surface-treated metal material according to claim 9 , wherein the aqueous organic resins (A′) and (B′) contain an anionic functional group.

13. The process for producing a surface-treated metal material according to claim 12 , wherein the anionic functional group is neutralized with an amine compound and the boiling point of the amine compound is not more than the maximum temperature of the metal material at the drying under heating to thereby form the coating film.

14. The process for producing a surface-treated metal material according to claim 9 , wherein the aqueous organic resin (A′) is a polyolefin resin or a polyurethane resin.

15. The process for producing a surface-treated metal material according to claim 9 , wherein the aqueous organic resin (B′) is a polyurethane resin.

16. The process for producing a surface-treated metal material according to claim 9 , wherein the dry thickness of the coating film is from 0.1 to 5 μm.

17. The process for producing a surface-treated metal material according to claim 9 , wherein the maximum temperature of the metal material at the drying under heating to thereby form the coating film satisfies the condition of from Tg_A (° C.) to Tg_B (° C.), wherein Tg_A (° C.) and Tg_B (° C.) represent the glass transition temperatures of the aqueous organic resins (A) and (B), respectively.

18. A surface-treated metal material comprising a metal material having on the surface thereof a coating film formed by the process for producing according to claim 9 .