ANTI-REFLECTIVE FILM, POLARIZING PLATE, AND DISPLAY APPARATUS

Abstract

The present disclosure relates to an anti-reflective film capable of simultaneously realizing high scratch resistance and antifouling property, and increasing a screen sharpness of a display apparatus, a polarizing plate and a display apparatus including the same.

Claims

1. An anti-reflective film comprising a hard coating layer; and a low refractive index layer containing a fluorine-containing compound, wherein a content of a fluorine atom existing on a surface of the low refractive index layer is more than 8.0 atomic %, and wherein a surface area difference percentage (SADP) of one surface of the low refractive index layer is 20% or less.

2. The anti-reflective film of claim 1, wherein a centerline average roughness (Ra) of the anti-reflective film is 10 nm or less.

3. The anti-reflective film of claim 1, wherein the surface area difference percentage (SADP) is defined by the following Equation 1.
Surface area difference percentage (%)=((three-dimensional area−two-dimensional area)/(two-dimensional area))×100.  [Equation 1]

4. The anti-reflective film of claim 1, wherein the content of fluorine atom is a content of fluorine atom relative to the total content of atoms existing within a thickness of 10 nm in the thickness direction of the low refractive index layer from one surface of the low refractive index layer.

5. The anti-reflective film of claim 1, wherein the fluorine-containing compound has a reactive functional group.

6. The anti-reflective film of claim 1, wherein the anti-reflective film has an average reflectance of 2% or less in a visible light wavelength range of 380 nm to 780 nm.

7. The anti-reflective film of claim 1, wherein the low refractive index layer further includes hollow inorganic particles.

8. The anti-reflective film of claim 7, wherein a content of the fluorine-containing compound relative to the total weight of the low refractive index layer is 2 to 9% by weight, and a content of the hollow inorganic particles relative to the total weight of the low refractive index layer is 29 to 60% by weight.

9. The anti-reflective film of claim 8, wherein the anti-reflective film satisfy the following Equation 2.
F≥0.26V−6.11  [Equation 2] wherein F is a content of the fluorine-containing compound and V is a content of the hollow inorganic particles.

10. The anti-reflective film of claim 1, wherein a content of fluorine atom contained in the fluorine-containing compound is 1 to 60% by weight.

11. The anti-reflective film of claim 1, wherein the low refractive index layer further includes a (co)polymer of a photopolymerizable compound.

12. The anti-reflective film of claim 1, wherein the low refractive index layer further includes a cross-linked polymer of a photopolymerizable compound, the fluorine-containing compound, and a polysilsesquioxane substituted with one or more reactive functional groups.

13. The anti-reflective film of claim 1, wherein the hard coating layer includes a binder resin including a photocurable resin; and organic or inorganic fine particles dispersed in the binder resin.

14. A polarizing plate comprising the anti-reflective film according to claim 1 and a polarizer.

15. A display apparatus comprising the anti-reflective film according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0112] FIGS. 1(a) and (b) are photographs of the surfaces of the anti-reflective films of Examples 2 and 3, respectively, taken with an atomic force microscope (AFM).

[0113] FIGS. 2(a) and (b) are photographs of the surfaces of the anti-reflective films of Comparative Examples 2 and 3, respectively, taken with an atomic force microscope (AFM).

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0114] Hereinafter, the present disclosure will be described in more detail by way of examples. However, these examples are given for illustrative purposes only, and the scope of the present disclosure is not intended to be limited to or by these examples.

Preparation Example 1: Coating Solution for Forming a Hard Coating Layer

[0115] 16.421 g of pentaerythritol triacrylate, 3.079 g of UA-306T (urethane acrylate series, reaction product of toluene diisocyanate and pentaerythritol triacrylate, manufactured by Kyoeisha), 6.158 g of 8BR-500 (photocurable urethane acrylate polymer, Mw 200,000, manufactured by Taisei Fine Chemical), 1.026 g of IRG-184 (initiator, Ciba), 0.051 g of Tego-270 (leveling agent, Tego), 0.051 g of BYK350 (leveling agent from BYK Chemie GmbH), 25.92 g of 2-butanol, 45.92 g of isopropyl alcohol, 0.318 g of XX-103BQ (copolymer particles of polystyrene and polymethyl methacrylate, manufactured by Sekisui Plastic, particle diameter of 2.0 μm, refractive index of 1.515), 0.708 g of XX-113BQ (copolymer particles of polystyrene and polymethyl methacrylate, manufactured by Sekisui Plastic, particle diameter of 2.0 μm, refractive index of 1.555), and 0.342 g of MA-ST (dispersion in which nano silica particles having a size of 10 to 15 nm are dispersed in methyl alcohol, manufactured by Nissan Chemical, 30% in MeOH) were mixed to prepare a coating solution for forming a hard coating layer.

Preparation Example 2: Preparation of a Coating Solution for Forming a Low Refractive Index Layer

[0116] The components shown in Table 1 were mixed to prepare a coating solution (C1 to C6) for forming a low refractive index layer.

TABLE-US-00001 TABLE 1 (Unit: g) C1 C2 C3 C4 C5 C6 TMPTA 0.103 0.126 0.1455 0.1068 0.1665 0.091 Hollow silica 0.7 0.9 0.84 0.7 0.84 1.10 particle dispersion (20% in MIBK) Solid silica particle 0.333 0.261 0 0.333 0 0 dispersion (40.6% in MIBK) KBM-5103 0.084 0.054 0 0.084 0 0 RS-923 dispersion 0.0255 0.04 0.0643 0.0179 0.0181 0.083 (40% in MIBK) Irgacure 127 0.005 0.03 0.02 0.005 0.02 0.02 Methyl isobutyl 2.87 4 3.827 2.87 3.97 3.34 ketone Diacetone alcohol 0.754 1.004 0.804 0.6767 0.6486 1.045 Isopropyl alcohol 5.532 6.997 6.202 5.493 6.234 5.673 2-butanol 0 0 3.20 0 3.20 2.90 t-butanol 0 3.66 0 3.33 0 0 [0117] TMPTA: trimethylolpropane triacrylate [0118] Hollow silica particle dispersion: diameter of about 42 nm to 66 nm, manufactured by JSC Catalyst and Chemicals (20% in MIBK) [0119] Solid silica particle dispersion: diameter of about 12 nm to 19 nm (40.6% in MIBK) [0120] KBM-5103: silane coupling agent, Shin-Etsu Silicone [0121] RS-923 dispersion: fluorine-containing compound, DIC (40% in MIBK), weight average molecular weight of 4450 g/mol) [0122] Irgacure 127: photoinitiator, Ciba

Examples and Comparative Examples: Preparation of Anti-Reflective Film

[0123] The coating solution for forming a hard coating layer of Preparation Example 1 was coated onto polyethylene terephthalate substrate (thickness of 2 μm, SRF PET, Toyobo), and dried to form a hard coating layer. The coating solution for forming a low refractive index layer described in Table 1 was coated onto the hard coating layer and dried to prepare an anti-reflective film.

[0124] Specifically, the prepared coating solution for forming a hard coating layer was coated onto the polyethylene terephthalate substrate with a #12 Mayer bar, then dried at a temperature of 60° C. for 2 minutes, and UV cured to form a hard coating layer (coating thickness of 5 μm). The UV lamp used an H bulb, and the curing reaction was carried out under a nitrogen atmosphere. The amount of UV light irradiated during curing is 48 mJ/cm.sup.2.

[0125] The coating solution for forming the low refractive index layer as shown in Table 2 below was coated onto the hard coating layer with a #4 Mayer bar so that the thickness becomes about 110 to 120 nm, dried and cured at a temperature of 90° C. for 1 minute. During the curing, the dried coating solution was irradiated with ultraviolet rays of 294 mJ/cm.sup.2 under a nitrogen purge to produce an anti-reflective film.

[0126] In addition, the hollow inorganic particle content (V) and the fluorine-containing compound content (F) relative to the total weight of the low refractive index layer formed by each of the coating solutions for forming the low refractive index layer (C1 to C6) were shown in Table 2 below. Further, it was confirmed whether the following Equation 2 was satisfied, and it was indicated either by ∘ if the Equation 2 was satisfied, or by X if not satisfied.

F≥0.26V−6.11  [Equation 2]

TABLE-US-00002 TABLE 2 Hollow Fluorine- Whether inorganic containing or not Low particle compound Equation refractive content content 2 is index layer (V, wt. %) (F, wt. %) satisfied Example 1 Coating 29.326 2.137 ◯ solution (C1) Example 2 Coating 35.159 3.125 ◯ solution (C2) Example 3 Coating 46.768 7.160 ◯ solution (C3) Comparative Coating 29.279 1.497 X Example 1 solution (C4) Comparative Coating 46.442 2.001 X Example 2 solution (C5) Comparative Coating 60.406 9.116 X Example 3 solution (C6)

[0127] Measurement and Evaluation

[0128] 1. Measurement of Fluorine Atom Content on the Surface of the Low Refractive Index Layer

[0129] The anti-reflective film obtained in the Examples and Comparative Examples was cut into 2 cm×2 cm (width×length), placed on a sample holder and fixed with a clip. Then, the surface of the low refractive index layer was analyzed using an X-ray Photoelectron Spectroscopy (K-Alpha™+XPS system, Thermo Fisher Scientific) equipment, and surveyed using Electron Spectroscopy for Chemical Analysis (ESCA). A narrow scan spectrum was obtained and qualitative and total quantitative analysis was performed. As a result, the content of fluorine atom on the surface of the low refractive index layer was obtained, and shown in Table 3 below.

[0130] On the other hand, the surface of the low refractive index layer means “within a thickness of 10 nm in the thickness direction of the low refractive index layer from one surface of the low refractive index layer (e.g., one surface of the low refractive index layer in contact with an air layer)”, and the content of fluorine on the surface of the low refractive index layer means a content of fluorine element relative to the total atomic content of elements existing within a thickness of 10 nm in the thickness direction of the low refractive index layer from one surface of the low refractive index layer (for example, one surface of the low refractive index layer in contact with an air layer).

[0131] 2. Measurement of Surface Area Difference Percentage (SADP) and Centerline Average Roughness (Ra)

[0132] In order to measure the surface shape of the anti-reflective film obtained in Examples and Comparative Examples, an atomic force microscope (Park Systems, XE7) was used. Specifically, the specimen was cut into 0.8 cm×0.8 cm (width×length) and attached to a sample stage using a carbon tape. The flat part was observed with an atomic force microscope. PPP-NCHR 10 (Force constant: 42 N/m, Resonance Frequency 330 kHz) was used as a tip for measurement, and detailed measurement conditions are as follows.

[0133] x-scan size: 1 μm, y-scan size: 1 μm

[0134] Scan rate: 0.7 to 1 Hz Z Servo Gain: 1

[0135] Set Point: 10 to 15 nm

[0136] The data measured under the above conditions were patterned using a XEI program, and executed under the following conditions.

[0137] Scope: Line, Orientation: X and Y axis

[0138] Regression order: 1

[0139] From the analyzed data, the surface area difference percentage and the centerline average roughness (Ra) were derived. In particular, the surface area difference percentage was calculated by substituting the two-dimensional/three-dimensional area in the following Equation 1, and the results are shown in Table 3 below.

Surface area difference percentage (%)=((three-dimensional area−two-dimensional area)/(two-dimensional area))×100  [Equation 1]

[0140] On the other hand, FIGS. 1(a) and (b) are photographs of the surfaces of the anti-reflective films of Examples 2 and 3, respectively, taken with an atomic force microscope (AFM), and FIGS. 2(a) and (b) are photographs of the surfaces of the anti-reflective films of Comparative Examples 2 and 3, respectively, taken with an atomic force microscope.

[0141] 3. Evaluation of Average Reflectance

[0142] For the anti-reflective films obtained in Examples and Comparative Examples, the average reflectance shown at a visible light range (380 to 780 nm) was measured using Solidspec 3700 (SHIMADZU), and the results are shown in Table 3 below.

[0143] 4. Evaluation of Antifouling Property

[0144] On the surface of the anti-reflective film obtained in the Examples and Comparative Examples, straight lines were drawn with a load of 50 g using Monami name black pen (for intermediate characters), and the interval between dewetting droplets formed using an optical microscope (Olympus, BX51) was measured 10 times or more, and the antifouling properties were judged based on the following criteria through the arithmetic mean value. The results are shown in Table 3 below.

[0145] <Judgment Criteria>

[0146] ∘: The arithmetic mean value of the intervals between dewetting droplets exceeds 200 μm

[0147] Δ: The arithmetic mean value of the intervals between dewetting droplets is 200 μm or less and more than 50 μm

[0148] X: The arithmetic mean value of the intervals between dewetting droplets is 50 μm or less, or no dewetting

TABLE-US-00003 TABLE 3 Surface Fluorine area Centerline Average content difference average reflect- Anti- (atomic percentage roughness ance fouling %) (%) (Ra, nm) (%) property Example 1 8.9 1.2 1.72 1.39 ◯ Example 2 11.3 2.36 2.87 1.37 ◯ Example 3 16.2 13.28 2.996 1.25 ◯ Compar- 7.3 1.27 1.75 2.23 Δ ative Example 1 Compar- 8.0 13.27 3.1 1.43 X ative Example 2 Compar- 15.5 21.13 5.04 1.16 Δ ative Example 3

[0149] According to Table 3, it was confirmed that Examples 1 to 3 had a fluorine atom content of more than 8.0 atomic % on the surface of the low-refractive layer, a surface area difference percentage of less than 20% and a centerline average roughness of 10 nm or less, whereby the average reflectance was as low as 1.41% or less, and the antifouling property was remarkably excellent compared to Comparative Examples 1 to 3.