Chrome-free composition of low temperature curing for treating a metal surface and a metal sheet using the same

1. A chromium-free, low-temperature curable, metal-surface treatment composition comprising: 5 to 30 parts by weight of a silane compound comprising, (a) a silane compound having an epoxy group, and a silane compound having an amino group, or (b) a hydrolytic condensate thereof, or a blend of (a) and (b); 0.1 to 5 parts by weight of a vanadium compound; 0.1 to 5 parts by weight of a magnesium compound; 1 to 10 parts by weight of organic/inorganic acids; 0.05 to 2 parts by weight of a crosslinking accelerating and coupling agent; 0.01 to 1 part by weight of an antifoaming agent; 1 to 2 parts by weight of a wetting agent; and the balance being water and ethanol, based on 100 parts by weight of the total solution.

2. The composition according to claim 1 , wherein the silane compound is selected from the group consisting of vinylmethoxysilane, vinyltrimethoxysilane, vinylepoxysilane, vinyltriepoxysilane, 3-aminopropyltriepoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-metaglycidoxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, N-(1,3-dimethylbutylidene)-3-(triepoxysilane)-1-propaneamine, N,N-bis[3-(trimethoxysilyl)propyl]ethylenediamine, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxy silane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxytrimethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, and N-[2-(vinylbenzylamino)ethyl]-3-aminopropyltrimethoxysilane.

3. The composition according to claim 1 , wherein the organic/inorganic acid is formic acid, ethylenediamine tetraacetic acid or phosphoric acid.

4. The composition according to claim 1 , wherein the vanadium compound is a vanadium compound having a vanadium oxidation number of 2 to 5, and the magnesium compound is selected from the group consisting of magnesium sulfate, magnesium nitrate and magnesium oxide.

5. The composition according to claim 4 , the vanadium compound is selected from the group consisting of vanadium pentoxide (V 2 O 5 ), vanadium trioxide (V 2 O 3 ), vanadium dioxide (VO 2 ), vanadium oxyacetylacetonate, vanadium acetylacetonate, vanadium trichloride (VCl 3 ), vanadium monoxide (VO), and ammonium metavanadate (NH 4 VO 3 ).

6. The composition according to claim 1 , wherein a zirconium or titanium compound is used as the crosslinking accelerating and coupling agent.

7. The composition according to claim 6 , wherein the titanium compound is at least one titanium compound selected from the group consisting of diisopropyl ditri-ethanolamino titanate, titanium lactate chelate and titanium acetylacetonate.

8. The composition according to claim 1 , wherein the antifoaming agent is N-methylethanolamine.

9. The composition according to claim 1 , wherein the wetting agent is isopropyl alcohol.

10. The composition according to claim 1 , wherein the pH of the composition is within the range of 3 to 7.

11. A steel sheet which is coated with a chromium-free, low-temperature curable, metal-surface treatment composition of claim 1 .

12. The steel sheet according to claim 11 , wherein a coating temperature of the metal-surface treatment composition is within a range of 30 to 250° C.

13. The steel sheet according to claim 11 , wherein a coating amount of a dry film of the metal-surface treatment composition is in a range of 0.05 to 1.0 g/m 2 .