Composition for forming coating layer having self-healing property, coating layer, and film

1. A composition for forming a coating layer having a self-healing property comprising:

a poly(C 2-4 alkylene glycol)-modified polyfunctional urethane (meth)acrylate-based binder;

a bifunctional or higher polyfunctional (meth)acrylate-based compound;

a UV initiator;

a polycarbonate-modified bifunctional urethane (meth)acrylate-based binder which has a bifunctional urethane bond and each polycarbonate-modified (meth)acrylate-based compound is bound to the urethane bond in the polycarbonate-modified bifunctional urethane (meth)acrylate-based binder; and

a silica nanoparticle which is dispersed in a cross-linked structure of the binder when the binder is in a cured state by UV irradiation,

wherein the poly(C 2-4 alkylene glycol)-modified polyfunctional urethane (meth)acrylate-based binder has a trifunctional or higher urethane bond and each poly(C 2-4 alkylene glycol)-modified (meth)acrylate-based compound is bound to the urethane bond in the poly(C 2-4 alkylene glycol)-modified polyfunctional urethane (meth)acrylate-based binder, and

at least two poly(C 2-4 alkylene glycol)-modified (meth)acrylate-based compounds bound to each urethane bond include poly(C 2-4 alkylene glycol) repeating units whose numbers of repetitions are different from each other.

2. The composition for forming a coating layer having a self-healing property of claim 1 , wherein the poly(C 2-4 alkylene glycol)-modified polyfunctional urethane (meth)acrylate-based binder includes at least one selected from the group consisting of polyethylene glycol-modified polyfunctional urethane (meth)acrylate-based binders and polypropylene glycol-modified polyfunctional urethane (meth)acrylate-based binders.

3. The composition for forming a coating layer having a self-healing property of claim 1 , wherein the poly(C 2-4 alkylene glycol)-modified polyfunctional urethane (meth)acrylate-based binder is formed by reacting a trifunctional or higher polyvalent isocyanate-based compound with at least two poly(C 2-4 alkylene glycol)-modified polyfunctional (meth)acrylate-based compounds containing poly(alkylene glycol) repeating units whose numbers of repetitions are different from each other.

4. The composition for forming a coating layer having a self-healing property of claim 3 , wherein the polyvalent isocyanate-based compound is selected from the group consisting of oligomers of diisocyanate compounds, polymers of diisocyanate compounds, cyclic polymers of diisocyanate compounds, hexamethylene diisocyanate isocyanurate, isophorone diisocyanate isocyanurate, toluene 2,6-diisocyanate isocyanurate, triisocyanate compounds and isomers thereof.

5. The composition for forming a coating layer having a self-healing property of claim 3 , wherein each of the at least two poly(C 2-4 alkylene glycol)-modified polyfunctional (meth)acrylate-based compounds have a number-average molecular weight of 200 to 1000.

6. The composition for forming a coating layer having a self-healing property of claim 5 , wherein the at least two poly(C 2-4 alkylene glycol)-modified polyfunctional (meth)acrylate-based compounds include at least one first compound having a number-average molecular weight of 200 to 500 and at least one second compound having a number-average molecular weight of 400 to 1000,

wherein the first and second compounds include poly(C 2-4 alkylene glycol) repeating units having different repeating numbers and have different number-average molecular weights.

7. The composition for forming a coating layer having a self-healing property of claim 1 , wherein the bifunctional or higher polyfunctional (meth)acrylate-based compound is selected from the group consisting of polyfunctional urethane acrylate, 9-ethylene glycol diacrylate (9-EGDA), bisphenol A epoxy acrylate, polyether triacrylate, pentaerythritol tri/tetraacrylate (PETA), dipentaerythritol hexa-acrylate (DPHA), trimethylolpropane triacrylate (TMPTA), and hexamethylene diacrylate (HDDA).

8. The composition for forming a coating layer having a self-healing property of claim 1 , wherein the silica nanoparticle has a particle diameter of 5 to 50 nm.

9. The composition for forming a coating layer having a self-healing property of claim 1 , comprising a composition for forming a binder comprising

50 to 90% by weight of the poly(C 2-4 alkylene glycol)-modified polyfunctional urethane (meth)acrylate-based binder,

5 to 45% by weight of the bifunctional or higher polyfunctional (meth)acrylate-based compound, and

1 to 10% by weight of the silica nanoparticle; and

0.1 to 5 parts by weight of the UV initiator based on 100 parts by weight of the composition for forming a binder.

10. A coating layer having a self-healing property comprising a binder layer in which a poly(C 2-4 alkylene glycol)-modified polyfunctional urethane (meth)acrylate-based binder and a (meth)acrylate group of bifunctional or higher polyfunctional (meth)acrylate-based compound are bound to each other to form a cross-linked structure;

a polycarbonate-modified bifunctional urethane (meth)acrylate-based binder which has a bifunctional urethane bond and each polycarbonate-modified (meth)acrylate-based compound is bound to the urethane bond in the polycarbonate-modified bifunctional urethane (meth)acrylate-based binder; and

a silica nanoparticle dispersed in the cross-linked structure of the binder layer,

wherein the binder layer has a cross-linking density of 5 mol/kg to 10 mol/kg,

wherein the poly(C 2-4 alkylene glycol)-modified polyfunctional urethane (meth)acrylate-based binder has a trifunctional or higher urethane bond and each poly(C 2-4 alkylene glycol)-modified (meth)acrylate-based compound is bound to the urethane bond in the poly(C 2-4 alkylene glycol)-modified polyfunctional urethane (meth)acrylate-based binder, and

at least two poly(C 2-4 alkylene glycol)-modified (meth)acrylate-based compounds bound to each urethane bond include poly(C 2-4 alkylene glycol) repeating units whose numbers of repetitions are different from each other.

11. The coating layer having a self-healing property of claim 10 , having a glass transition temperature of 10 to 30° C.

12. A film having a self-healing property comprising the coating layer having a self-healing property of claim 10 .

13. The film having a self-healing property of claim 12 , further comprising a substrate layer supporting the coating layer.

14. The film having a self-healing property of claim 13 , wherein the substrate layer has a thickness of 50 to 400 μm, and the coating layer has a thickness of 10 to 100 μm.

15. The film having a self-healing property of claim 12 , further comprising a protective film layer formed on the coating layer and a cohesive layer formed between the coating layer and the protective film layer.

16. The film having a self-healing property of claim 13 , further comprising a printing layer formed under the substrate layer and an adhesive layer formed under the printing layer.

17. A molded product to which the film of claim 12 is adhered.

18. The molded product of claim 17 , which is a household appliance, mobile phone, automobile interior material or display device.