COMPOSITION FOR FORMING COATING LAYER HAVING SELF-HEALING PROPERTY, COATING LAYER, AND FILM

Abstract

The present invention relates to a composition for forming a coating layer having a self-healing property which enables the provision of a film exhibiting further improved mechanical properties together with excellent self-healing properties by being applied to the exterior of various household appliances or display devices, etc., a coating layer and a film. The composition for forming a coating layer having a self-healing property comprises: a poly(C.sub.2-4 alkylene glycol)-modified polyfunctional urethane (meth)acrylate-based binder; a bifunctional or higher polyfunctional (meth)acrylate-based compound; a UV initiator; and a silica nanoparticle, wherein the binder has a trifunctional or higher urethane bond and each poly(C.sub.2-4 alkylene glycol)-modified (meth)acrylate-based compound is bound to the urethane bond in the binder, and at least two poly(C.sub.2-4 alkylene glycol)-modified (meth)acrylate-based compounds bound to each urethane bond include poly(C.sub.2-4 alkylene glycol) repeating units whose numbers of repetitions are different from each other.

Claims

1. A composition for forming a coating layer having a self-healing property comprising: a poly(C2-4 alkylene glycol)-modified polyfunctional urethane (meth)acrylate-based binder; a bifunctional or higher polyfunctional (meth)acrylate-based compound; a UV initiator; and a silica nanoparticle, wherein the binder has a trifunctional or higher urethane bond and each poly(C2-4 alkylene glycol)-modified (meth)acrylate-based compound is bound to the urethane bond in the binder, and at least two poly(C2-4 alkylene glycol)-modified (meth)acrylate-based compounds bound to each urethane bond include poly(C2-4 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(C2-4 alkylene glycol)-modified polyfunctional (meth)acrylate-based binder includes at least one selected from the group consisting of polyethylene glycol-modified polyfunctional (meth)acrylate-based binders and polypropylene glycol-modified polyfunctional (meth)acrylate-based binders.

3. The composition for forming a coating layer having a self-healing property of claim 1, further comprising a polycarbonate-modified bifunctional urethane (meth)acrylate-based binder which has a bifunctional or higher urethane bond and each polycarbonate-modified (meth)acrylate-based compound is bound to the urethane bond in the binder.

4. The composition for forming a coating layer having a self-healing property of claim 1, wherein the poly(C2-4 alkylene glycol)-modified polyfunctional (meth)acrylate-based binder is formed by reacting a trifunctional or higher polyvalent isocyanate-based compound with at least two poly(C2-4 alkylene glycol)-modified polyfunctional (meth)acrylate-based compounds containing poly(alkylene glycol) repeating units whose numbers of repetitions are different from each other.

5. The composition for forming a coating layer having a self-healing property of claim 4, 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.

6. The composition for forming a coating layer having a self-healing property of claim 4, wherein each of the at least two poly(C2-4 alkylene glycol)-modified polyfunctional (meth)acrylate-based compounds have a number-average molecular weight of 200 to 1000.

7. The composition for forming a coating layer having a self-healing property of claim 6, wherein the at least two poly(C2-4 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(C2-4 alkylene glycol) repeating units having different repeating numbers and have different number-average molecular weights.

8. The composition for forming a coating layer having a self-healing property of claim 1, wherein the 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).

9. (canceled)

10. 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.

11. (canceled)

12. 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(C2-4 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 an initiator based on 100 parts by weight of the composition for forming a binder.

13. (canceled)

14. A coating layer having a self-healing property comprising a binder layer in which a poly(C2-4 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; 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.

15. The coating layer having a self-healing property of claim 14, having a glass transition temperature of 10 to 30° C.

16. The coating layer having a self-healing property of claim 14, wherein the binder has a trifunctional or higher urethane bond and each poly(C2-4 alkylene glycol)-modified (meth)acrylate-based compound via is bound to the urethane bond in the binder, and at least two poly(C2-4 alkylene glycol)-modified (meth)acrylate-based compounds bound to each urethane bond include poly(C2-4 alkylene glycol) repeating units whose numbers of repetitions are different from each other.

17. A film having a self-healing property comprising the coating layer having a self-healing property of claim 14.

18. The film having a self-healing property of claim 17, further comprising a substrate layer supporting the coating layer.

19. (canceled)

20. The film having a self-healing property of claim 18, wherein the substrate layer has a thickness of 50 to 400 μm, and the coating layer has a thickness of 10 to 100 μm.

21. The film having a self-healing property of claim 17, further comprising a protective film formed on the coating layer and a cohesive layer formed between the coating layer and protective film layer.

22. The film having a self-healing property of claim 18, further comprising a printing layer formed under the substrate layer and an adhesive layer formed under the printing layer.

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

24. The molded product of claim 23, which is a household appliance, mobile phone, automobile interior material or display device.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0065] FIG. 1 shows a graph comparing the FT-IR spectra before and after the progress of the urethane reaction for the production of the polyethylene glycol-modified polyfunctional urethane (meth)acrylate-based binder in Preparation Example 1.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0066] Hereinafter, the present invention will be described in more detail by way of Examples. However, these Examples are given for illustrative purposes only, and the scope of the invention is not intended to be limited by these Examples.

Preparation Example 1: Preparation of Polyethylene Glycol-Modified Polyfunctional Urethane (Meth)Acrylate-Based Binder

[0067] DN980S manufactured by Aekyung Chemical, which is an HDI-based trimer, was used as a trifunctional or higher polyvalent isocyanate-based compound, and as the polyethylene glycol-modified (meth)acrylate-based compounds, a polyethylene glycol monoacrylate (Mn=300) and a polyethylene glycol monoacrylate (Mn=500) having different number-average molecular weights by including polyethylene glycol repeating units having different repeating numbers were each used.

[0068] 40 g of polyvalent isocyanate-based compound, 30 g of polyethylene glycol monoacrylate (Mn=300) and 30 g of polyethylene glycol monoacrylate (Mn=500) were mixed with 0.1 g of DBTDL (dibutyl tin dilaurate) and 200 g of methyl ethyl ketone, and the mixture was stirred at 60° C. for about 5 hours to carry out a urethane reaction.

[0069] By the completion of the urethane reaction, the polyethylene glycol-modified polyfunctional urethane (meth)acrylate-based binder of Preparation Example 1 was prepared. The progress of the urethane reaction and the formation of the binder were confirmed via FT-IR. For reference, the FT-IR spectra before and after the urethane reaction are shown in FIG. 1. With reference to FIG. 1, it was confirmed that the peak derived from the isocyanate group (—NCO) appearing at the position of about 2268.5 cm.sup.−1 disappeared, thereby confirming the progress of the urethane reaction and the formation of the binder.

Preparation Example 2: Preparation of Polypropylene Glycol-Modified Polyfunctional Urethane (Meth)Acrylate-Based Binder

[0070] DN980S manufactured by Aekyung Chemical, which is an HDI-based trimer, was used as a trifunctional or higher polyvalent isocyanate-based compound, and as the polypropylene glycol-modified (meth)acrylate-based compounds, a polypropylene glycol monoacrylate (Mn=400) and a polypropylene glycol monoacrylate (Mn=600) having a different number-average molecular weight by including polypropylene glycol repeating units having different repeating numbers were each used.

[0071] 40 g of polyvalent isocyanate compound, 40 g of polypropylene glycol monoacrylate (Mn=400) and 40 g of polypropylene glycol monoacrylate (Mn=600) were mixed with 0.15 g of DBTDL (dibutyl tin dilaurate) and 300 g of methyl ethyl ketone, and the mixture was stirred at 60° C. for about 5 hours to carry out a urethane reaction.

[0072] By the completion of the urethane reaction, the polypropylene glycol-modified polyfunctional urethane (meth)acrylate-based binder of Preparation Example 2 was prepared. The progress of the urethane reaction and the formation of the binder were confirmed by the disappearance of the peak derived from the isocyanate group (—NCO) appearing at about 2268.5 cm.sup.−1 via FT-IR as in Preparation Example 1.

Comparative Preparation Example 1: Preparation of Polyethylene Glycol-Modified Polyfunctional Urethane (Meth)Acrylate-Based Binder

[0073] The polyethylene glycol-modified polyfunctional urethane (meth)acrylate-based binder was prepared in the same manner as in Preparation Example 1, except that only 60 g of polyethylene glycol monoacrylate (Mn=500) was used without using the polyethylene glycol monoacrylate (Mn=300) in Preparation Example 1. The progress of the urethane reaction and the formation of the binder were confirmed via FT-IR.

Comparative Preparation Example 2: Preparation of Polyethylene Glycol-Modified Polyfunctional Urethane (Meth)Acrylate-Based Binder

[0074] The polyethylene glycol-modified polyfunctional urethane (meth)acrylate-based binder was prepared in the same manner as in Preparation Example 1, except that a bifunctional HDI (diisocyanate compound) was used instead of using the DN980S manufactured by Aekyung Chemical, which is a HDI-based trimer, in Preparation Example 1. The progress of the urethane reaction and the formation of the binder were confirmed via FT-IR.

Examples 1 and 2: Preparation of Compositions for Forming Coating Layer Having Self-Healing Property

[0075] The polyethylene glycol-modified polyfunctional urethane (meth)acrylate-based binder obtained in Preparation Example 1, pentaerythritol triacrylate (PETA), as a bifunctional or higher polyfunctional (meth)acrylate-based compound, and silica nanoparticles having a particle size of 30 nm were mixed in the amounts shown in Table 1 below to form a composition for forming a binder.

[0076] The compositions of Examples 1 and 2 were prepared by mixing 2 parts by weight of UV initiator (Irgacure 184), 1 part by weight of leveling agent and 35 parts by weight of methyl ethyl ketone based on 100 parts by weight of the composition for forming a binder.

Example 3: Preparation of Composition for Forming Coating Layer Having Self-Healing Property

[0077] The polypropylene glycol-modified polyfunctional urethane (meth)acrylate-based binder obtained in Preparation Example 2, pentaerythritol triacrylate (PETA), as a bifunctional or higher polyfunctional (meth)acrylate-based compound, and silica nanoparticles having a particle size of 30 nm were mixed in the amounts shown in Table 1 below to form a composition for forming a binder.

[0078] The composition of Example 3 was prepared by mixing 2 parts by weight of UV initiator (Irgacure 184), 1 part by weight of leveling agent and 35 parts by weight of methyl ethyl ketone based on 100 parts by weight of the composition for forming a binder.

Example 4: Preparation of Composition for Forming Coating Layer Having Self-Healing Property

[0079] The polyethylene glycol-modified polyfunctional urethane (meth)acrylate-based binder and the polypropylene glycol-modified polyfunctional urethane (meth)acrylate-based binder obtained in Preparation Examples 1 and 2, respectively, pentaerythritol triacrylate (PETA), as a bifunctional or higher polyfunctional (meth)acrylate-based compound, and silica nanoparticles having a particle size of 30 nm were mixed in the amounts shown in Table 1 below to form a composition for forming a binder.

[0080] The composition of Example 4 was prepared by mixing 2 parts by weight of UV initiator (Irgacure 184), 1 part by weight of leveling agent and 35 parts by weight of methyl ethyl ketone based on 100 parts by weight of the composition for forming a binder.

Example 5: Preparation of Composition for Forming Coating Layer Having Self-Healing Property

[0081] The polyethylene glycol-modified polyfunctional urethane (meth)acrylate-based binder obtained in Preparation Example 1, dipentaerythritol hexa-acrylate (DPHA), as a bifunctional or higher polyfunctional (meth)acrylate-based compound, and silica nanoparticles having a particle size of 30 nm were mixed in the amounts shown in Table 1 below to form a composition for forming a binder.

[0082] The composition of Example 5 was prepared by mixing 2 parts by weight of UV initiator (Irgacure 184), 1 part by weight of leveling agent and 35 parts by weight of methyl ethyl ketone based on 100 parts by weight of the composition for forming a binder

Comparative Examples 1 and 2: Preparation of Compositions for Forming Coating Layer Having Self-Healing Property

[0083] The binders of Comparative Examples 1 and 2 were each prepared in the same manner as in Example 1, except that the binders obtained in Comparative Preparation Examples 1 and 2 were used instead of the binder of Preparation Example 1, in Example 1.

TABLE-US-00001 TABLE 1 Specific compositions of Examples 1 to 5 and Comparative Examples 1 and 2 Content of Content of Content of Content of silica binder (wt %; PETA (wt %; DPHA (wt %; nanoparticles based on the based on the based on the (wt %; based on content of the content of the content of the the content of composition for composition for composition for the composition forming a forming a forming a for forming a Types of binder binder) binder) binder) binder) Example 1 Preparation 85 10 5 Example 1 Example 2 Preparation 75 20 5 Example 1 Example 3 Preparation 75 20 5 Example 2 Example 4 Preparation 35 + 35 25 5 Example 1 + Preparation Example 2 Example 5 Preparation 75 20 5 Example 1 Comparative Comparative 85 10 5 Example 1 Preparation Example 1 Comparative Comparative 85 10 5 Example 2 Preparation Example 2

Experimental Example: Formation of Coating Layer and Film, and Evaluation of Physical Properties

[0084] The compositions obtained in Examples 1 to 5 and Comparative Examples 1 and 2 were each coated onto a PET film with a meyer bar No. 40, then dried in an oven at 60° C. for 2 minutes, and irradiated with ultraviolet rays with an intensity of 100 mJ/cm.sup.2 to form coating layers having a self-healing property and films independently.

[0085] The physical properties of the coating layers were measured and evaluated in the following manner.

[0086] 1. Cross-Linking Density:

[0087] The cross-linking density was measured and evaluated by swelling the coating layer according to the Flory-Rehner equation. More specifically, after measuring the initial mass (Mi) of the coating layer sample (sample size: 2 cm in width, 7 cm in length and 100 μm in thickness), the sample was immersed in 50 ml of toluene solvent for 168 hours and then taken out to measure the final mass (Mf) of the swelled sample. From the initial and final masses, the change in mass was calculated by the equation of ΔM=Mf−Mi. The volume change percentage of the swelled coating layer sample was calculated from the change in mass (AM), and the calculated value was introduced to the Flory-Rehner equation to finally calculate the cross-linking density.

[0088] 2. Tg:

[0089] The glass transition temperature of the coating layers was measured by using DSC.

[0090] 3. Self-Healing Property:

[0091] The surface of the coating layer was rubbed 30 times back and forth with a copper brush having a load of 750 g, and then the time at which the scratch was healed at room temperature was visually confirmed and measured.

[0092] 4. Pencil Hardness:

[0093] The pencil hardness of the coating layer was measured according to JIS K5400 with a load of 500 g.

[0094] 5. Measurement of Scratch Resistance:

[0095] The steel wool (#0000) was rubbed 10 times back and forth with a constant load, and then the occurrence of scratches on the surface of the coating layer was visually observed. By repeating the measurements with increasing the load, the scratch resistance was evaluated at the maximum load immediately before the occurrence of scratches. The results of the physical properties measured above are summarized in Table 2 below.

TABLE-US-00002 TABLE 2 Evaluation results of the physical properties of Examples 1 to 3 and Comparative Examples 1 and 2 Example Example Example Example Example Comparative Comparative 1 2 3 4 5 Example 1 Example 2 Cross-linking 5.55 5.96 6.62 6.23 9.10 3.25 1.20 density(mol/kg) Tg(° C.) 13 17 23 21 35 10 −10 Self-healing <1 75 10 15 120 Not Not property second seconds seconds seconds seconds healed healed Pencil B HB HB HB HB 2B 2B hardness Scratch 200 g OK 300 g OK 300 g OK 300 g OK 300 g OK 100 g OK 50 g OK resistance

[0096] With reference to Table 1, it was confirmed that the coating layers of Examples 1 to 5 satisfying the predetermined ranges of cross-linking density and Tg also exhibited excellent mechanical properties such as hardness and scratch resistance, etc., while exhibiting excellent self-healing properties. In contrast, it was confirmed that the coating layers of Comparative Examples 1 and 2 not only could not exhibit the self-healing properties, but also showed poor mechanical properties such as hardness and scratch resistance, etc.