UV curable coating composition

Abstract

Provided is a UV curable coating composition, and more particularly, to a UV curable coating composition including: at least one polyfunctional epoxy oligomer; at least one epoxy compound; at least one non-hydrolyzed epoxy silane; at least one polyfunctional acrylic compound; at least two photoinitiators; and at least one surfactant. The UV curable coating composition according to the present invention can be coated on various substrates and provide excellent adhesion and scratch resistance to the coating layer regardless of a substrate type unlike conventional coating compositions.

Claims

1. A UV curable coating composition, comprising: at least one polyfunctional epoxy oligomer; at least one epoxy compound; at least one non-hydrolyzed epoxy silane; at least one polyfunctional acrylic compound; at least two photoinitiators; and at least one surfactant, wherein the viscosity of the at least one polyfunctional epoxy oligomer is 23,000 to 40,000 cps at 25° C., and wherein the at least one polyfunctional epoxy oligomer is prepared through dehydration condensation after mixing at least one polyhydric alcohol and epichlorohydrin to form chlorohydrin ether.

2. The UV curable coating composition of claim 1, wherein the content of the at least one polyfunctional epoxy oligomer is 20 to 45 wt % with respect to the total weight of the UV curable coating composition, the content of the at least one epoxy compound is 5 to 25 wt % with respect to the total weight of the UV curable coating composition, the content of the at least one non-hydrolyzed epoxy silane is 10 to 50 wt % with respect to the total weight of the UV curable coating composition, the content of the at least one polyfunctional acrylic compound is 1 to 30 wt % with respect to the total weight of the UV curable coating composition, the content of the at least two photoinitiators is 0.1 to 15 wt % with respect to the total weight of the UV curable coating composition, and the content of the at least one surfactant is 0.01 to 10 wt % with respect to the total weight of the UV curable coating composition.

3. The UV curable coating composition of claim 2, wherein the content of at the least one polyfunctional epoxy oligomer is 25 to 40 wt % with respect to the total weight of the UV curable coating composition, the content of the at least one epoxy compound is 10 to 25 wt % with respect to the total weight of the UV curable coating composition, the content of the at least one non-hydrolyzed epoxy silane is 20 to 30 wt % with respect to the total weight of the UV curable coating composition, the content of the at least one polyfunctional acrylic compound is 10 to 20 wt % with respect to the total weight of the UV curable coating composition, the content of the at least two photoinitiators is 0.1 to 10 wt % with respect to the total weight of the UV curable coating composition, and the content of the at least one surfactant is 0.1 to 5 wt % with respect to the total weight of the UV curable coating composition.

4. The UV curable coating composition of claim 1, wherein the at least one polyhydric alcohol has at least one structure of Chemical Formulas 1 to 3 below: ##STR00005## wherein R.sub.1 is C.sub.3-C.sub.8 alkyl substituted with at least one hydroxyl, R.sub.2 is hydroxyl or C.sub.1-C.sub.5 alkyl, and n is an integer of 1 to 4.

5. The UV curable coating composition of claim 1, wherein the at least one polyhydric alcohol is at least one alcohol selected from the group consisting of glycerin, diglycerin, polyglycerin, trimethylolpropane, sorbitol and pentaerythritol.

6. The UV curable coating composition of claim 1, wherein the at least one non-hydrolyzed epoxy silane has a structure represented by Chemical Formula 4 below: ##STR00006## wherein R.sub.3 is C.sub.1-C.sub.5 alkyl, R.sub.4 is C.sub.1-C.sub.5 alkylene or C.sub.1-C.sub.5 alkyleneoxy, and X is C.sub.2-C.sub.8 alkylene oxide or C.sub.3-C.sub.8 cycloalkylene oxide.

7. The UV curable coating composition of claim 1, wherein the at least one polyfunctional acrylic compound is at least one compound selected from the group consisting of 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, and trimethylolpropane triacryate.

8. The UV curable coating composition of claim 1, wherein the at least two photoinitiators include at least one cationic photoinitiator and at least one free radical photoinitiator, respectively.

9. The UV curable coating composition of claim 8, wherein the at least one cationic photoinitiator is at least one photoinitiator selected from the group consisting of triarylsulfonium salts and diaryliodonium salts.

10. The UV curable coating composition of claim 8, wherein the at least one free radical photoinitiator is selected from the group consisting of chloromethylbenzophenone, ethyl benzoin ether, isopropyl benzoin ether, diethoxy acetophenone, α,α-dimethoxy-α-phenylacetophenone, (1-(4-(4-hydroxyethoxy)-phenyl-2-hydroxy-2-methyl-1-propane-1-one, 1-hydroxy-cyclohexyl phenyl ketone, and 2-hydroxy-2-methyl-1-phenyl-propan-1-one.

11. A substrate coated with the UV curable coating composition of claim 1.

12. The substrate of claim 11, wherein a material of the substrate is selected from the group consisting of polythiol urethane, polyacryl, polyamide, polyimide, polysulfone, polycarbonate, a polycarbonate-poly(ethylene terephthalate) copolymer, and polyaryl carbonate.

13. Lenses coated with the UV curable coating composition of claim 1.

Description

EXAMPLE 1

Preparation of Polyfunctional Epoxy Oligomer

(1) 1) Oligomer A

(2) 182 g of sorbitol and 555 g of epichlorohydrin were placed in a 2 L four-necked flask equipped with a decompression reflux device, and the temperature was increased to 50° C. 500 ppm of SnCl.sub.2.H.sub.2O was added thereto, and the temperature was increased to about 150° C., and the reaction was performed while stirring for 6 hours. After 491 g of methyl isobutyl ketone was added to the mixture which was reacted, 300 g of a 50% sodium hydroxide aqueous solution was added, and then while the mixture was slowly dropped at 70° C., the dehydration condensation reaction was performed by reducing the pressure.

(3) After the reaction was completed, distilled water and methyl isobutyl methane were added to separate an aqueous layer and an organic layer, and only the organic layer was separated, the water was removed with MgSO.sub.4, methyl isobutyl ketone as an organic solvent was removed under reduced pressure to obtain oligomer A (1.29 (25° C.) of specific gravity, 26,000 cps (25° C.) of viscosity, and 92% of yield).

(4) 2) Oligomer B

(5) Except for using 150 g of trimethylol propane instead of sorbitol, oligomer B (1.27 (25° C.) of specific gravity, 23,000 cps (25° C.) of viscosity, and 94% of yield) was obtained in the same manner as oligomer A.

EXAMPLE 2

Preparation of UV Curable Resin Composition

(6) In order to prepare the UV curable coating compositions in Experimental Examples 1 to 9 and Comparative Examples 1 to 3, components and contents of the composition in Examples and Comparative Examples were prepared as illustrated in Table 1.

(7) The acrylic compound, the epoxy oligomer, the epoxy silane and the epoxy compound were added into a 3-necked flask at once and fully mixed for 6 hours at room temperature, and then a photoinitiator and a surfactant were added thereto, and then mixed for about 2 hours by blocking all light sources. When the mixing was completed, the mixture was filtered using a 1 micro filter in a space where the light source was blocked to obtain a coating composition.

(8) TABLE-US-00001 TABLE 1 Component and contents of coating compositions in Experimental Examples 1 to 9 and Comparative Examples 1 to 3 Experi- Experi- Experi- Experi- Experi- Experi- mental mental mental mental mental mental No Example Example Example Example Example Example Component 1 2 3 4 5 6 Epoxy Oligomer A 33.21 35 37.32 12.21 oligomer Oligomer B 23.52 38.41 38.28 Epoxy Trimethylol 16.49 12.8 12.88 14.27 13.79 11.72 compound propane triglycidyl ether Sorbitol aliphatic polyglycidyl ether Epoxy 2-(3,4-epoxy- 3.3 silane cyclohexyl) ethyltrimethoxy silane 3-glycidoxy- 24.52 propylmethyl- dimethoxy silane 3-glycidoxypropyl 28 24.7 28 25 28 trimethoxy silane 3-glycidoxypropyl 3.28 trimethoxy silane 2-(3,4-epoxy- cyclohexyl) ethyltrimethoxy silane Acrylic 1,4-butanediol 17.5 17.8 compound diacrylate 1,6-hexanediol 17.8 17.8 17.8 17.8 diacrylate Pentaerythritol 2.2 triacrylate Dipentaerythritol tetraacrylate photoinitiator Triarylsulfonium 3.2 3.2 3.2 3.2 3.2 3.2 hexafluoro- antimonate salt Triarylsulfonium 0.6 0.8 hexafluoro phosphate salt 2-hydroxy-2- 1 1 1 1 1 1 metal-1-phenyl- propan-1-one surfactant Polysiloxane- 0.4 0.4 0.4 0.4 0.4 0.4 based surfactant Total amount 100 100 100 100 100 100 Viscosity of composition (25° C., cps) 82 67 65 72 58 56 Experi- Experi- Experi- Compar- Compar- Compar- mental mental mental ative ative ative No Example Example Example Example Example Example Component 7 8 9 1 2 3 Epoxy Oligomer A oligomer Oligomer B 28.11 38.11 28.43 Epoxy Trimethylol 5.31 8.07 17.58 51 51 compound propane triglycidyl ether Sorbitol aliphatic 17.58 4.52 1.48 48 polyglycidyl ether Epoxy 2-(3,4-epoxy- silane cyclohexyl) ethyltrimethoxy silane 3-glycidoxy- propylmethyl- dimethoxy silane 3-glycidoxypropyl 27 25 25 25 28 25 trimethoxy silane 3-glycidoxypropyl trimethoxy silane 2-(3,4-epoxy- 3.21 cyclohexyl) ethyltrimethoxy silane Acrylic 1,4-butanediol 19.5 compound diacrylate 1,6-hexanediol 17.8 17.8 19.5 19.5 diacrylate Pentaerythritol triacrylate Dipentaerythritol 2.2 2.2 tetraacrylate photoinitiator Triarylsulfonium 3.2 3.3 3.3 3.5 3.5 3.5 hexafluoro- antimonate salt Triarylsulfonium hexafluoro phosphate salt 2-hydroxy-2- 1 1 1 1 1 1 metal-1-phenyl- propan-1-one surfactant Polysiloxane- 0.4 0.4 0.4 0.4 0.4 0.4 based surfactant Total amount 100 100 100 100 100 100 Viscosity of composition (25° C., cps) 61 58 52 25 28 28

EXAMPLE 3

Coating Substrate

(9) The compositions of Table 1 were coated on CR-39, MR-8, polycarbonate substrates using a MIDAS spin coater and photocured through a UV curing machine manufactured by FOURSLAMP.

(10) Specifically, all the substrates before coating were washed with isopropyl alcohol (IPA) and DI-water (distiller water), and then the water was completely removed so that there was no water. The washed substrate was placed on a spin coater center chuck and coated by increasing a speed of 500 to 1000 rpm while applying the liquid. The coated substrate was then exposed to a UV curing machine having a UV power of 1 J/m.sup.2 for about 40 seconds to cure the coating film. The environment in which the coating proceeded was maintained at room temperature of 25° C. and humidity of 50% or less.

(11) Table 2 shows physical properties of the respective coating layers formed by coating the UV-curable coating compositions in Experimental Examples 1 to 9 and Comparative Examples 1 to 3 on the CR-39, MR-8 and polycarbonate substrates by the method.

(12) TABLE-US-00002 TABLE 2 Physical properties of respective coating layers, when coating UV-curable coating compositions in Experimental Examples 1 to 9 and Comparative Examples 1 Adhesion (3) Before After UV UV weather weather Trans- Scratch resistance resistance mittance resistance test test Tintability No. Substrate (1) (2) (QUV) (QUV) (4) (5) Experi- CR-39 95 B 5B 3B 45 mental MR-8 95 B 5B 1B 67 Example PC 93 B 5B 5B 73 1 Experi- CR-39 97 B 5B 5B 47 mental MR-8 97 B 5B 5B 53 Example PC 96 C 5B 5B 65 2 Experi- PC 95 C 5B 5B 53 mental Example 3 Experi- CR-39 95 C 5B 3B 28 mental PC 94 C 5B 5B 48 Example 4 Experi- CR-39 97 B 4B 0B 45 mental MR-8 97 B 3B 0B 51 Example PC 96 B 5B 5B 67 5 Experi- PC 94 C 5B 5B 42 mental Example 6 Experi- CR-39 95 B 3B 0B 43 mental MR-8 95 B 2B 0B 52 Example PC 94 B 5B 5B 62 7 Experi- CR-39 97 B 3B 0B 42 mental MR-8 97 B 1B 0B 51 Example PC 96 B 5B 5B 58 8 Experi- PC 96 B 5B 5B 58 mental Example 9 Compar- CR-39 93 C 5B 5B 15 ative MR-8 92 C 5B 5B 28 Example PC 87 D 5B 0B 40 1 Compar- CR-39 92 E 5B 5B 8 ative MR-8 90 E 5B 5B 17 Example PC 85 E 5B 0B 35 2 Compar- CR-39 92 D 5B 5B 12 ative MR-8 92 D 5B 5B 21 Example PC 87 D 5B 0B 42 3 (1) Transmittance: 550 nm transmittance-using ASC model 350 (2) Scratch resistance:-Observed using Olympus BX53M microscope after #0000 steel wool 1 kg load 10 stroks A (None), B (1 or 2 scratches), C (less than 5 scratches), D (multiple scratches), E (substrate scratch) (3) Adhesion: Crosshatch test (ASTM D3359, Nichiban CR-24 tape 5 times)-observed using Olympus BX53M microscope 5B (0%), 4B (less than 5%), 3B (5 to 15%), 2B (15 to 35%), 1B (35 to 65%), 0B (more than 65%) (4) Verification of adhesion using crosshatch test after UV weather resistance test (QUV test) (Nichiban CR-24 tape 5 times)-observed using Olympus BX53M microscope QUV conditions: (i) 8-hour UV power setting (340 nm/0.7 w/m.sup.2 .Math. nm), 60° C. (ii) Bubble spraying (condensation) at 50° C. for 4 hours (iii) Repeat processes (i) and (ii) once more: Total 24 hours (5) Tintability: Transmittance was measured at 550 nm after immersing BPI black dye at 95° C. for 10 minutes

(13) Although the specific part of the present disclosure has been described in detail, it is obvious to those skilled in the art that such a specific description is just a preferred embodiment and the scope of the present disclosure is not limited. Therefore, the substantial scope of the present invention will be defined by the appended claims and equivalents thereof.