ANTI-REFLECTIVE FILM

Abstract

The present disclosure relates to an anti-reflective film comprising: a hard coating layer; and a low refractive index layer, wherein a particle-mixed layer containing both hollow inorganic nanoparticles and solid inorganic nanoparticles and having a thickness of 1.5 nm to 22 nm exists in the low refractive index layer, and wherein the anti-reflective film has a ratio of the reflectance at a wavelength of 400 nm to the reflectance at a wavelength of 550 nm of 1.3 to 2.7, and a polarizing plate, a display device, and an organic light emitting diode display device comprising the anti-reflective film.

Claims

1. An anti-reflective film comprising: a hard coating layer; and a low refractive index layer, wherein a particle-mixed layer containing both hollow inorganic nanoparticles and solid inorganic nanoparticles and having a thickness of 1.5 nm to 22 nm exists in the low refractive index layer, and wherein the anti-reflective film has a ratio of the reflectance at a wavelength of 400 nm to the reflectance at a wavelength of 550 nm of 1.3 to 2.7.

2. The anti-reflective film according to claim 1, wherein the anti-reflective film has a reflectance of more than 0.5% and 1.5% or less at a wavelength of 550 nm.

3. The anti-reflective film according to claim 1, wherein the anti-reflective film has a reflectance of 1.0% to 3.5% at a wavelength of 400 nm.

4. The anti-reflective film according to claim 1, wherein the particle-mixed layer has a thickness of 2.0 nm to 20 nm.

5. The anti-reflective film according to claim 1, wherein the thickness of the particle-mixed layer is determined by fitting a polarization ellipticity measured by an ellipsometry method to a diffusion layer model.

6. The anti-reflective film according to claim 1, wherein the low refractive index layer is formed on one surface of the hard coating layer, and the particle-mixed layer is located at a distance of 15 nm to 60 nm from the one surface of the hard coating layer.

7. The anti-reflective film according to claim 1, wherein the low refractive index layer has a thickness of 20 nm to 240 nm.

8. The anti-reflective film according to claim 1, wherein the hard coating layer has a surface energy of more than 34 mN/m.

9. The anti-reflective film according to claim 1, wherein the low refractive index layer is formed on one surface of the hard coating layer, the low refractive index layer comprises hollow inorganic nanoparticles and solid inorganic nanoparticles dispersed in a binder resin, 50% by volume or more of the entire solid inorganic nanoparticles in the low refractive index layer exist between the one surface of the hard coating layer and the particle-mixed layer.

10. The anti-reflective film according to claim 6, wherein a region between the one surface of the hard coating layer and the particle-mixed layer has a refractive index of 1.46 to 1.65 at a wavelength of 550 nm.

11. The anti-reflective film according to claim 9, wherein in the low refractive index layer, 50% by volume or more of the entire hollow inorganic nanoparticles exist in a region from the particle-mixed layer to one surface of the low refractive index layer opposite from the hard coating layer.

12. The anti-reflective film according to claim 11, wherein the region from the particle-mixed layer to one surface of the low refractive index layer opposite from the hard coating layer has a refractive index of 1.0 to 1.40 at a wavelength of 550 nm.

13. The anti-reflective film according to claim 1, wherein the solid inorganic nanoparticles have a diameter of 0.5 to 100 nm, and the hollow inorganic nanoparticles have a diameter of 1 to 200 nm.

14. The anti-reflective film according to claim 1, wherein a difference in density between the solid inorganic nanoparticles and the hollow inorganic nanoparticles is 0.50 g/cm.sup.3 to 3.00 g/cm.sup.3.

15. The anti-reflective film according to claim 1, wherein the low refractive index layer comprises a binder resin, and hollow inorganic nanoparticles and solid inorganic nanoparticles dispersed in the binder resin, and the binder resin included in the low refractive index layer comprises a crosslinked (co)polymer between a (co)polymer of a photopolymerizable compound and a fluorine-containing compound including a photoreactive functional group.

16. The anti-reflective film according to claim 1, wherein the hard coating layer comprises a binder resin including a photocurable resin, and organic or inorganic fine particles dispersed in the binder resin.

17. A polarizing plate comprising the anti-reflective film of claim 1 and a polarizer.

18. A display device comprising the anti-reflective film of claim 1.

19. An organic light emitting diode display device comprising the anti-reflective film of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0183] FIG. 1 shows the reflectance pattern of the anti-reflective film of Example 1.

[0184] FIG. 2 shows the reflectance pattern of the anti-reflective film of Example 2.

[0185] FIG. 3 shows the reflectance pattern of the anti-reflective film of Example 3.

[0186] FIG. 4 shows the reflectance pattern of the anti-reflective film of Example 4.

[0187] FIG. 5 shows the reflectance pattern of the anti-reflective film of Example 5.

[0188] FIG. 6 shows the reflectance pattern of the anti-reflective film of Example 6.

[0189] FIG. 7 shows the reflectance pattern of the anti-reflective film of Comparative Example 1.

[0190] FIG. 8 shows the reflectance pattern of the anti-reflective film of Comparative Example 2.

[0191] FIG. 9 shows the reflectance pattern of the anti-reflective film of Comparative Example 3.

[0192] FIG. 10 shows the reflectance pattern of the anti-reflection film of Comparative Example 4.

[0193] Hereinafter, the present disclosure will be described in more detail in the following examples. However, these examples are given for illustrative purposes only and the content of the present disclosure is not intended to be limited to or by the examples in any way.

PREPARATION EXAMPLES 1 TO 2: PREPARATION OF HARD COATING LAYER

Preparation Example 1: Preparation of Hard Coating Layer HD1

[0194] Solid components of 75 g of trimethylolpropane trimethacrylate (TMPTA), 2 g of silica fine particles having an average particle diameter of 20 nm (surface treatment: 3-methacryloyloxypropylmethyldimethoxysilane), 0.05 g of fluorine-based acrylate (RS-537, DIC) and 1.13 g of photoinitiator (Irgacure 184, Ciba) were diluted in a MEK (methyl ethyl ketone) solvent so that a solid content concentration was 40 wt. %, thereby preparing a hard coating composition.

[0195] The diluted hard coating solution was coated onto a triacetyl cellulose film using a #10 mayer bar, dried and photocured under the conditions of Table 1 below to prepare a hard coating film having a thickness of 5 μm.

[0196] The wind speed applied during drying of the hard coating layer in each of the following Examples and Comparative Examples is shown in Table 2 below.

Preparation Example 2: Preparation of Hard Coating Layer HD2

[0197] Solid components of 75 g of trimethylolpropane trimethacrylate (TMPTA), 2 g of silica fine particles having an average particle diameter of 20 nm (surface treatment: 3-methacryloyloxypropylmethyldimethoxysilane), 0.5 g of fluorine-based acrylate (RS-537, DIC) and 1.13 g of photoinitiator (Irgacure 184, Ciba) were diluted in a MEK (methyl ethyl ketone) solvent so that the solid content concentration was 40 wt. %, thereby preparing a hard coating composition.

[0198] The diluted hard coating solution was coated onto a triacetyl cellulose film using a #10 mayer bar, dried and photocured under the conditions of Table 1 below to prepare a hard coating film having a thickness of 5 μm.

[0199] The wind speed applied during drying of the hard coating layer in each of the following Examples and Comparative Examples is shown in Table 2 below.

TABLE-US-00001 TABLE 1 Nitrogen purging UV intensity during photocuring [mJ/cm.sup.2] Preparation Example 1 ◯  25 mJ/cm.sup.2 Preparation Example 2 ◯ 254 mJ/cm.sup.2

PREPARATION EXAMPLES 3 TO 6: PREPARATION OF LOW REFRACTIVE INDEX LAYER COATING COMPOSITION

Preparation Example 3: Preparation of Photocurable Coating Composition for Preparing Low Refractive Index Layer

[0200] Based on 100 parts by weight of trimethylolpropane trimethacrylate (TMPTA), 281 parts by weight of hollow silica nanoparticles (diameter: about 50 to 60 nm, density: 1.96 g/cm.sup.3, manufactured by JSC Catalyst and Chemicals), 63 parts by weight of solid silica nanoparticles (diameter: about 12 nm, density: 2.65 g/cm.sup.3, Nissan Chemical), 131 parts by weight of a first fluorine-containing compound (X-71-1203M, Shin-Etsu), 19 parts by weight of a second fluorine-containing compound (RS-537, DIC), and 31 parts by weight of an initiator (Irgacure 127, Ciba) were diluted in a mixed solvent of methyl isobutyl ketone (MIBK):diacetone alcohol (DAA):isopropyl alcohol in a weight ratio of 3:3:4 so that the solid content concentration was 3 wt. %.

Preparation Example 4: Preparation of Photocurable Coating Composition for Preparing Low Refractive Index Layer

[0201] Based on 100 parts by weight of trimethylolpropane trimethacrylate (TMPTA), 200 parts by weight of hollow silica nanoparticles (diameter: about 50 to 60 nm, density: 1.96 g/cm.sup.3, manufactured by JSC Catalyst and Chemicals), 48 parts by weight of solid silica nanoparticles (diameter: about 12 nm, density: 2.65 g/cm.sup.3, Nissan Chemical), 111 parts by weight of a first fluorine-containing compound (X-71-1203M, Shin-Etsu), 15 parts by weight of a second fluorine-containing compound (RS-537, DIC), and 21 parts by weight of an initiator (Irgacure 127, Ciba) were diluted in a mixed solvent of methyl isobutyl ketone (MIBK):diacetone alcohol (DAA):isopropyl alcohol in a weight ratio of 3:3:4 so that the solid content concentration was 3 wt. %.

Preparation Example 5: Preparation of Photocurable Coating Composition for Preparing Low Refractive Index Layer

[0202] Based on 100 parts by weight of trimethylolpropane trimethacrylate (TMPTA), 300 parts by weight of hollow silica nanoparticles (diameter: about 60 to 70 nm, density: 1.79 g/cm.sup.3, manufactured by JSC Catalyst and Chemicals), 85 parts by weight of solid silica nanoparticles (diameter: about 12 nm, density: 2.65 g/cm.sup.3, Nissan Chemical), 150 parts by weight of a first fluorine-containing compound (X-71-1203M, Shin-Etsu), 33 parts by weight of a second fluorine-containing compound (RS-537, DIC), and 35 parts by weight of an initiator (Irgacure 127, Ciba) were diluted in a mixed solvent of methyl isobutyl ketone (MIBK):diacetone alcohol (DAA):isopropyl alcohol in a weight ratio of 3:3:4 so that the solid content concentration was 3 wt. %.

Preparation Example 6: Preparation of Photocurable Coating Composition for Preparing Low Refractive Index Layer

[0203] Based on 100 parts by weight of trimethylolpropane trimethacrylate (TMPTA), 248 parts by weight of hollow silica nanoparticles (diameter: about 60 to 60 nm, density: 1.96 g/cm.sup.3, manufactured by JSC Catalyst and Chemicals), 68 parts by weight of solid silica nanoparticles (diameter: about 12 nm, density: 2.65 g/cm.sup.3, Nissan Chemical), 120 parts by weight of a first fluorine-containing compound (X-71-1203M, Shin-Etsu), 33 parts by weight of a second fluorine-containing compound (RS-537, DIC), and 30 parts by weight of an initiator (Irgacure 127, Ciba) were diluted in a mixed solvent of methyl isobutyl ketone (MIBK):diacetone alcohol (DAA):isopropyl alcohol in a weight ratio of 3:3:4 so that the solid content concentration was 3 wt. %.

EXAMPLE AND COMPARATIVE EXAMPLE: PREPARATION OF LOW REFRACTIVE INDEX LAYER AND ANTI-REFRACTIVE FILM

[0204] The photocurable coating composition obtained above was coated onto a hard coating layer of Preparation Examples 1 to 2 at a thickness of 120 nm using a #4 mayer bar, dried and cured under the conditions of Table 2 below.

[0205] At the time of curing, it proceeded under nitrogen purging, and the drying was performed at a temperature was 90° C. for 1 minute.

TABLE-US-00002 TABLE 2 Hard coating layer Low refractive Hard coating drying wind speed (m/s) index layer Example 1 Preparation Example 1 0.5 Preparation Example 3 Example 2 Preparation Example 1 0.5 Preparation Example 4 Example 3 Preparation Example 1 1.0 Preparation Example 4 Example 4 Preparation Example 1 0.5 Preparation Example 5 Example 5 Preparation Example 1 0.5 Preparation Example 6 Example 6 Preparation Example 1 1.0 Preparation Example 6 Comparative Preparation Example 1 0.3 Preparation Example 6 Example 1 Comparative Preparation Example 2 0.3 Preparation Example 5 Example 2 Comparative Preparation Example 2 0.5 Preparation Example 5 Example 3 Comparative Preparation Example 2 0.7 Preparation Example 3 Example 4

EXPERIMENTAL EXAMPLE: MEASUREMENT OF PHYSICAL PROPERTIES OF ANTI-REFLECTIVE FILM

[0206] The following experiments were performed for the anti-reflective films obtained in Examples and Comparative Examples.

[0207] 1. Measurement of Surface Energy of Hard Coating Film

[0208] The surface energies of the hard coating layers of each of Examples and Comparative Examples were measured by determining a contact angle of DI water (Gebhardt) and diiodomethane (Owens) at 10 points using a contact angle measuring apparatus DSA-100 (Kruss), calculating the average value, and then converting the average contact angle into the surface energy. In the measurement of the surface energy, the contact angle was converted into the surface energy by using Dropshape Analysis software and applying the following Equation 2 of the OWRK (Owen, Wendt, Rable, Kaelble) method to the program.

γ.sub.L(1+cos θ)=2√{square root over (γ.sub.S.sup.Dγ.sub.L.sup.D)}+2√{square root over (γ.sub.S.sup.Pγ.sub.L.sup.P)}  [Equation 2]

[0209] 2. Measurement of Reflectance of Anti-Reflective Film and b* in CIE Lab Color Space

[0210] For the anti-reflective films obtained in Examples and Comparative Examples, the reflectance and b* at each wavelength in the visible light region (380 to 780 nm) were measured using a Solidspec 3700 (SHIMADZU) equipment. After scanning the specimen from 380 nm to 780 nm and measuring the reflectance at each wavelength, the average reflectance and b* were derived using the UV-2401PC Color Analysis program.

[0211] 3. Measurement of Anti-Fouling Property

[0212] Three straight lines were drawn with a red permanent marker on the surface of the anti-reflective films obtained in Examples and Comparative Examples. Then, the anti-fouling property was evaluated through the number of erasing times when rubbing with a nonwoven cloth.

[0213] <Measurement Standard>

[0214] ◯: Erase when rubbing 10 times or less

[0215] Δ: Erase when rubbing 11 to 20 times

[0216] X: Erase when rubbing 20 times or more

[0217] 4. Measurement of Scratch Resistance

[0218] The surface of the anti-reflective films obtained in Examples and Comparative Examples was rubbed back and forth 10 times with steel wool (#0000) under a load at a speed of 27 rpm. The scratch resistance was obtained by measuring the maximum load at which a scratch of 1 cm or less observed with the naked eye was 1 or less.

[0219] 5. Ellipsometry Measurement

[0220] For the anti-reflective films each obtained in Examples and Comparative Examples, the polarization ellipticity was measured by an ellipsometry method.

[0221] Specifically, the ellipsometry was measured for the antireflection films each obtained in Examples and Comparative Examples at an incidence angle of 70° in a wavelength range of 380 nm to 1000 nm using a J. A. Woollam Co. M-2000 apparatus.

[0222] The measured ellipsometry data (ψ, λ) was fitted to a Cauchy model of the following Equation 1 for Layer 1 and Layer 2 of the lower refractive index layer using Complete EASE software.

[00003]$\begin{array}{cc}n\left(\lambda \right)=A+\frac{B}{{\lambda }^2}+\frac{C}{{\lambda }^4}& \left[\mathrm{Equation}1\right]\end{array}$

[0223] in the above Equation 1, n(λ) is a refractive index at a wavelength λ, λ is in a range of 300 nm to 1800 nm, and A, B, and C are Cauchy parameters.

[0224] In addition, for the mixed layer of the low refractive index layer, the refractive index and thickness were fitted to a diffuse layer model. MSE of The Cauchy model and the diffuse layer model was set to be 5 or less.

[0225] 6. Measurement of Refractive Index

[0226] For the mixed particle layer included in the low refractive index layer obtained in Examples, the refractive indexes at wavelengths of 550 nm and 400 nm were calculated using a polarization ellipticity measured at a wavelength of 380 nm to 1,000 nm, a Cauchy model, and a diffuse layer model.

TABLE-US-00003 TABLE 3 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Average reflectance (%) 0.9 1.35 1.42 0.6 1.1 1.2 b value in CIE Lab color 3.3 2.9 1.2 1.5 2.5 2.1 space Surface energy of hard 35 35 35 35 35 35 coating layer [mN/m] Position of the particle-mixed 32 45 40 31 51 16 layer from the hard coating layer (nm) Thickness of the particle- 2.5 11.1 12.9 8.62 5.8 18.1 mixed layer (nm) Reflectance of anti-reflective 0.8093 1.1233 1.3193 0.598 0.9895 1.121 film at a wavelength of 550 nm Reflectance of anti-reflective 1.3768 2.5755 2.3928 1.299 1.7627 1.5946 film at a wavelength of 400 nm Ratio of reflectance at 1.70 2.29 1.81 2.17 1.78 1.42 wavelength 400 nm to reflectance at wavelength 550 nm Scratch resistance (g) 500 500 500 500 500 500 Anti-fouling ◯ ◯ ◯ ◯ ◯ ◯ Phase separation ◯ ◯ ◯ ◯ ◯ ◯

TABLE-US-00004 TABLE 4 Comparative Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 4 Average reflectance (%) 0.92 0.7 0.75 0.84 b value in CIE Lab color space 4.2 5.1 4.5 −7.73 Surface energy of hard coating layer 33 32 33 34 [mN/m] Position of the particle-mixed layer 11 10 65 13.4 from the hard coating layer (nm) Thickness of the particle-mixed 22.12 25.98 31.58 1.31 layer (nm) Reflectance of anti-reflective film 0.875 0.5877 0.6521 0.78 at a wavelength of 550 nm Reflectance of anti-reflective film 2.3886 1.9539 1.9844 2.55 at a wavelength of 400 nm Ratio of reflectance at wavelength 2.73 3.32 3.04 3.27 400 nm to reflectance at wavelength 550 nm Scratch resistance (g) 150 50 200 100 Anti-fouling X X X X Phase separation X X X X

[0227] As shown in Table 3, it was confirmed that the anti-refractive films of Examples, in which a particle-mixed layer containing both hollow inorganic nanoparticles and solid inorganic nanoparticles and having a thickness of 1.5 nm to 22 nm exists in the low refractive index layer, realize a reflectance of 1.5% or less at a wavelength of 550 nm, and also the ratio of the reflectance at a wavelength of 400 nm to the reflectance at a wavelength of 550 nm is 1.3 to 2.7.

[0228] Further, from the results of Table 3, it was confirmed that the anti-reflective films of Examples are phase-separated so as to divide the regions in which the hollow inorganic nanoparticles and the solid inorganic nanoparticles are mainly distributed while including the mixed layer in the low refractive index layer, and thus the anti-reflective films realizes high scratch resistance and excellent anti-fouling properties, and at the same time, the absolute value of b* in the CIE Lab color space has a low color value of 4 or less, which can have colorless and transparent properties.

[0229] On the contrary, as shown in Table 4, in the anti-reflective films of Comparative Examples, it appears that regions where the hollow inorganic nanoparticles and the solid inorganic nanoparticles are mainly distributed are divided, and thus not unevenly distributed (phase separated), confirming that scratch resistance or anti-fouling properties are not sufficient.

[0230] In addition, from the results of Table 4, it appears that a particle-mixed layer having a thickness of more than 22 nm exists in the low refractive index layer of the anti-reflective films of Comparative Examples, or the particle-mixed layer is located excessively close to or too far from the hard coating layer, and it was confirmed that in the anti-reflective films of these Comparative Examples, the ratio of the reflectance at a wavelength of 400 nm to the reflectance at a wavelength of 550 nm exceeds 2.7, the films show a blue color and have an opacity or color property to a degree that is not suitable for application to a polarizing plate or a display device.