Ultraviolet curable resin composition for transparent color-painted steel sheet, and steel sheet using same

1. A UV curable resin composition, comprising:

25 to 45 parts by weight of a modified epoxy acrylate oligomer;

10 to 25 parts by weight of a urethane acrylate oligomer;

21 to 80 parts by weight of a reactive acryl monomer;

1 to 20 parts by weight of a photoinitiator; and

0.1 to 10 parts by weight of an additive,

wherein the reactive acryl monomer is composed of 20 to 50 parts by weight of a monofunctional reactive acryl monomer and 1 to 30 parts by weight of a bifunctional reactive acryl monomer.

2. The composition according to claim 1 , wherein the modified epoxy acrylate oligomer is a urethane-modified epoxy acrylate oligomer.

3. The composition according to claim 1 , wherein the urethane acrylate oligomer is a reaction product of diisocyanate and (meth)acrylate including a hydroxy group.

4. The composition according to claim 3 , wherein the diisocyanate is isophoronediisocyanate or dicyclohexanediisocyanate.

5. The composition according to claim 1 , wherein the monofunctional reactive acryl monomer includes at least one selected from the group consisting of acryl morpholine (ACMO), tetrahydroperfuryl acrylate (THFA), hydroxy ethyl acrylate (HEA), hydroxy propyl acrylate (HPA) and isobonyl acrylate (IBOA).

6. The composition according to claim 1 , wherein the bifunctional reactive acryl monomer includes at least one selected from the group consisting of diethylene glycol diacrylate (DEGDA), dipropylene glycol diacrylate (DPGDA), tripropylene glycol diacrylate (TPGDA), hexanediol diacrylate (HDDA), polyethylene glycol 400 diacrylate (PEG 400DA) and poylethylene glycol 600 diacrylate (PEG 600DA).

7. A steel sheet which has a coating film formed by coating the UV curable resin composition according to claim 1 .

8. The steel sheet according to claim 7 , wherein a transparent or color-painted chrome-free coating film is formed on at least one surface of the steel sheet,

a UV curable resin composition is coated on at least one surface of the transparent or color-painted chrome-free coating film.

9. The steel sheet according to claim 8 , wherein the transparent or color-painted chrome-free coating film includes a composition for treating the surface of a metal comprising:

a) 100 parts by weight of a water-soluble organic resin-inorganic binder complex resin;

b) 1 to 10 parts by weight of an anti-corrosive and corrosion-resistant agent; and

c) 1 to 10 parts by weight of a metal chelating agent, on the basis of the total solid content.

10. The steel sheet according to claim 9 , wherein the water-soluble organic resin-inorganic binder complex resin is a composition for treating the surface of a metal obtained by reacting an organic resin, an inorganic binder and a coupling agent.

11. The steel sheet according to claim 10 , wherein the inorganic binder is a composition for treating the surface of a metal comprising at least one selected from the group consisting of silica sol, alumina sol, titania sol and zirconia sol, and which has a particle size of 5 to 30 nm.

12. The steel sheet according to claim 9 , wherein the anti-corrosive and corrosion-resistant agent is selected, when the composition for surface treating of a metal is an acid solution, from the group consisting of an aluminum phosphate aqueous solution, a manganese phosphate aqueous solution, a zinc phosphate aqueous solution, a molybdenum phosphate aqueous solution, and a fluorine phosphate soda aqueous solution, which include phosphoric acid as a stabilizer; and when the composition for surface treating of a metal is a base solution, from the group consisting of a hexaammonium hepta molybdate solution, a diammonium dihydrophosphate solution, an ammonium vanadate solution, a sodium vanadate solution, an ammonium zirconium carbonate solution, and an ammonium fluorozirconate solution, which include an amine as a stabilizer.

13. The steel sheet according to claim 8 , wherein the transparent or color-painted chrome-free coating film has a thickness of 0.5 to 2 μm, and the coating film formed on the transparent or color-painted chrome-free coating film by coating the UV curable resin composition has a thickness of 0.5 to 10 μm.

14. A steel sheet which has a coating film formed by coating the UV curable resin composition according to claim 1 .