ANTI-REFLECTIVE FILM, POLARIZING PLATE, AND DISPLAY APPARATUS

Abstract

The invention relates to an anti-reflective film that has low reflectance deviation and light transmittance deviation, can simultaneously realize high scratch resistance and anti-fouling property, and can increase screen sharpness of a display apparatus, a polarizing plate and a display apparatus comprising the same.

Claims

1. An anti-reflective film comprising a light transmitting substrate; a hard coating layer; and a low refractive index layer, wherein a first peak appears at 2θ value of 25 to 27°, and a second peak appears at 2θ value of 46 to 48°, in X-ray diffraction (XRD) pattern of reflection mode, and a rate (P2/P1) of the intensity of the second peak (P2) to the intensity of the first peak (P1) is at least 0.01.

2. The anti-reflective film according to claim 1, wherein the light transmitting substrate has a moisture permeability under temperature of 30 to 40° C. and relative humidity of 90 to 100%, of 50 g/m.sup.2.Math.day or less.

3. The anti-reflective film according to claim 1, wherein the low refractive index layer comprises a binder resin and inorganic fine particles dispersed in the binder resin.

4. The anti-reflective film according to claim 3, wherein the binder resin comprises a crosslinked polymer between photopolymerizable compounds and fluorine-containing compounds including photoreactive functional groups.

5. The anti-reflective film according to claim 3, wherein the inorganic fine particles include one or more selected from the group consisting of solid inorganic nanoparticles having a diameter of 0.5 to 100 m, and hollow inorganic nanoparticles having a diameter of 1 to 200 nm.

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

7. The anti-reflective film according to claim 6, wherein the binder resin of the hard coating layer further comprises a high molecular weight (co)polymer having a number average molecular weight of at least 10,000.

8. The anti-reflective film according to claim 1, wherein the light transmitting substrate has thickness direction retardation (Rth) measured at a wavelength of 400 nm to 800 nm, of at least 5,000 nm, a rate of a tensile strength in a direction perpendicular to one direction to a tensile strength in the one direction, of at least 2, and the tensile strength in one direction is smaller than the tensile strength in a direction perpendicular to the one direction.

9. The anti-reflective film according to claim 1, wherein a light transmitting substrate is a polyethylene terephthalate film.

10. The anti-reflective film according to claim 1, wherein the anti-reflective film has average reflectance in the wavelength region of 380 nm to 780 nm, of 2.0% or less.

11. The anti-reflective film according to claim 1, wherein the anti-reflective film has an average reflectance deviation of 0.2% p or less, and a light transmittance deviation of 0.2% p or less.

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

13. A polarizing plate comprising a polarizer; a second hard coating layer with a thickness of 10 μM or less; and the anti-reflective film according to claim 1, wherein the second hard coating layer and the anti-reflective film are positioned so as to face based on the polarizer.

14. The polarizing plate according to claim 13, wherein a total thickness of the polarizer; the second hard coating layer; and the anti-reflective film is 200 μM or less.

15. The polarizing plate according to claim 13, wherein the second hard coating layer with a thickness of 10 μM or less is positioned on one side of the polarizer, and the light transmitting substrate of the antireflective film is positioned on the other side, wherein the light transmitting substrate has thickness direction retardation (Rth) measured at a wavelength of 400 nm to 800 nm, of at least 5,000 nm, wherein the light transmitting substrate has a rate of a tensile strength in a direction perpendicular to one direction to a tensile strength in the one direction, of at least 2, and wherein the tensile strength in one direction is smaller than the tensile strength in a direction perpendicular to the one direction.

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

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0138] FIG. 1 shows the X-ray diffraction (XRD) pattern of the anti-reflective film of Example 1.

[0139] The invention will be explained in detail in the following Examples. However, these examples are presented only as the illustrations of the invention, and the scope of the invention is not limited thereby.

PREPARATION EXAMPLE 1: PREPARATION OF A COATING SOLUTION FOR FORMING A HARD COATING LAYER

[0140] The components described in the following Table 1 were mixed to prepare coating solutions (B1, B2 and B3) for forming a hard coating layer.

TABLE-US-00001 TABLE 1 (unit: g) B1 B2 B3 DPHA 6.237 PETA 16.421 10.728 13.413 UA-306T 3.079 2.069 6.114 8BR-500 6.158 6.537 6.114 IRG-184 1.026 1.023 1.026 Tego-270 0.051 0.051 0.051 BYK350 0.051 0.051 0.051 2-butanol 25.92 32.80 36.10 IPA 45.92 38.80 35.70 XX-10313Q(2.0 gm, RI 1.515) 0.318 0.460 0.600 XX-11313Q(2.0 gm, RI 1.555) 0.708 0.563 0.300 MA-ST(30% in MeOH) 0.342 0.682 0.542 DPHA: dipentaerythritol hexaacrylate PETA: pentaerythritol triacrylate UA-306T: urethane acrylate, a reaction product of toluene diisocyanate and pentaerythritol triacrylate (a product from Kyoeisha) 8BR-500: photocurable urethane acrylate polymer (Mw 200,000, a product from Taisei Fine Chemical) IRG-184: initiator (Irgacure 184, Ciba Company) Tego-270: leveling agent from Tego Company BYK350: leveling agent from BYK Company IPA isopropyl alcohol XX-103BQ (2.0 μm, Refractive index 1.515): copolymer particles of polystyrene and polymethyl methacrylate(product from Sekisui Plastic) XX-113BQ (2.0 μm, Refractive index 1.555): copolymer particles of polystyrene and polymethyl methacrylate(product from Sekisui Plastic) MA-ST (30% in MeOH): dispersion in which nanosilica particles having a size of 10~15 nm are dispersed in methyl alcohol (product from Nissan Chemical)

PREPARATION EXAMPLE 2-1: PREPARATION OF A COATING SOLUTION (C1) FOR FORMING A LOW REFRACTIVE INDEX LAYER

[0141] 100 g of trimethylolpropane triacrylate (TMPTA), 283 g of hollow silica nanoparticles (diameter range: about 42 nm to 66 nm, product from JSC catalyst and chemicals), 59 g of solid silica nanoparticles (diameter range: about 12 nm to 19 nm), 115 g of a first fluorine-containing compound (X-71-1203M, ShinEtsu), 15.5 g of a second fluorine-containing compound (RS-537, DIC) and 10 g of an initiator (Irgacure 127, Ciba Company) were diluted in a solvent of MIBK (methyl isobutyl ketone) such that solid content concentration became 3 wt %, thus preparing a coating solution for forming a low refractive index layer (a photocurable coating composition).

PREPARATION EXAMPLE 2-2: PREPARATION OF A COATING SOLUTION (C2) FOR FORMING A LOW REFRACTIVE INDEX LAYER

[0142] 100 g of dipentaerythritol hexaacrylate (DPHA), 143 g of hollow silica nanoparticles (diameter range: about 51 nm to 72 nm, product from JSC catalyst and chemicals), 29 g of solid silica nanoparticles (diameter range: about 12 nm to 19 nm), 56 g of a fluorine-containing compound (RS-537, DIC) and 3.1 g of an initiator (Irgacure 127, Ciba Company) were diluted in a solvent of MIBK (methyl isobutyl ketone) such that solid content concentration became 3.5 wt %, thus preparing a coating solution for forming a low refractive index layer (a photocurable coating composition).

EXAMPLES 1 TO 4 AND COMPARATIVE EXAMPLES 1 TO 4: PREPARATION OF ANTI-REFLECTIVE FILMS

[0143] On each light transmitting substrate (thickness 80 μm) described in the following Table 2, each coating solution (B1, B2, B3) for forming a hard coating layer prepared above was coated with #12 mayer bar, and then, dried at 60° C. for 2 minutes, and UV cured to form a hard coating layer (coating thickness 5 μm). As an UV lamp, H bulb was used, and a curing reaction was progressed under nitrogen atmosphere. The quantity of UV irradiated during curing was 100 mJ/cm.sup.2.

[0144] On the hard coating layer, each coating solution (C1, C2) for forming a low refractive index layer was coated with #4 mayer bar to a thickness of about 110 to 120 nm, and dried at 40° C. for 1 minute and cured. During curing, UV was irradiated at 252 mJ/cm.sup.2 to the dried coating solution under nitrogen purging.

TABLE-US-00002 TABLE 2 Anti-reflective film Light transmitting Tensile substrate Hard Low strength Thickness direction coating refractive rate* retardation (Rth, nm) layer index layer Example 1 4.1 9300 Coating Coating solution solution (B1) (C1) Example 2 4.0 9200 Coating Coating solution solution (B2) (C1) Example 3 2.9 9230 Coating Coating solution solution (B2) (C1) Example 4 3.7 9300 Coating Coating solution solution (B3) (C1) Example 5 2.2 5800 Coating Coating solution solution (B1) (C2) Comparative 1.8 3500 Coating Coating Example 1 solution solution (B3) (C1) Comparative 1.6 3000 Coating Coating Example 2 solution solution (B2) (C1) Comparative 1.3 3200 Coating Coating Example 3 solution solution (B2) (C1) Comparative 1.8 1500 Coating Coating Example 4 solution solution (B1) (C2) *tensile strength rate: a rate of tensile strength in a direction perpendicular to one direction, having large value, to tensile strength in one direction, having smaller value, in the light transmitting substrate, The tensile strength of the light transmitting substrate is measured according to JIS C-2318.

[0145] Evaluation

[0146] 1. Evaluation of X-Ray Diffraction (XRD) of Reflection Mode

[0147] For the anti-reflective films obtained in Examples and Comparative Examples, 2 cm*2 cm (width*length) samples were prepared, and then, Cu-Kα rays of 1.54 Å wavelength were irradiated to measure X-ray diffraction (XRD) pattern of reflection mode.

[0148] Specifically, on a low background silicon holder (Bruker CorporationE), the sample was fixed without being lifted, and as the measuring apparatus, Bruker AXS D4 Endeavor XRD was used. The voltage and current used were respectively 40 kV and 40 mA, and the optics and detector used were as follows. [0149] Primary (incident beam) optics: motorized divergence slit, soller slit 2.3° [0150] Secondary (diffracted beam) optics: soller slit 2.3° [0151] LynxEye detector (1D detector)

[0152] The measurement mode was a coupled 2θ/θ mode, and a region having 2θ of 6° to 70° was measured using FDS (Fixed Divergence Slit) 0.3°, every 0.04° for 175 seconds.

[0153] Thereafter, a peak appearing at 2θ value of 25 to 27° is designated as a first peak, a peak appearing at 2θ value of 46 to 48° is designated as a second peak, and the 2θ values were respectively described in the following Table 3. And, a rate (P2/P1) of the strength of the second peak (P2) to the strength of the first peak (P1) was calculated, and the result was described in the following Table 3.

[0154] Meanwhile, FIG. 1 shows a X-ray diffraction (XRD) pattern of the anti-reflective film of Example 1.

[0155] 2. Evaluation of Average Reflectance

[0156] The rear side (one side of the light transmitting substrate on which a hard coating layer is not formed) of each anti-reflective film obtained in Examples and Comparative Examples was darkened, and then, average reflectance in the wavelength region of 380 nm to 780 nm was measured using a reflectance mode of Solidspec 3700 (SHIMADZU), and the results were shown in the following Table 3.

[0157] 3. Evaluation of Average Reflectance Deviation

[0158] For each anti-reflective film obtained in Examples and Comparative Examples, 20 points were randomly selected, and for each point, average reflectance was measured by the method of 2. Evaluation of Average Reflectance. Thereafter, the arithmetic mean of the measured average reflectances of 20 points was calculated. Thereafter, a difference (absolute value) between the average reflectance at each point and the arithmetic mean was defined as average reflectance deviation, and each average reflectance deviation was calculated at each of 20 points. Among the 20 average reflectance deviations, the largest average reflectance deviation was described in the following Table 3.

[0159] 4. Evaluation of Light Transmittance Deviation

[0160] For each anti-reflective film obtained in Examples and Comparative Examples, 20 points were randomly selected, and for each point, light transmittance was measured.

[0161] Specifically, average light transmittance in the wavelength region of 380 to 780 nm was measured using a transmittance mode of Solidspec 3700 (SHIMADZU).

[0162] Thereafter, the arithmetic mean of the measured light transmittances of 20 points was calculated. Thereafter, a difference (absolute value) between the light transmittance at each point and the arithmetic mean was defined as light transmittance deviation, and each light transmittance deviation was calculated at each of 20 points. Among the 20 light transmittance deviations, the largest light transmittance deviation was described in the following Table 3.

[0163] 5. Evaluation of Moisture Permeability

[0164] The moisture permeability of each anti-reflective film obtained in Examples and Comparative Examples was measured at a temperature of 38° C. and relative humidity of 100%, using MOCON test apparatus (PERMATRAN-W, MODEL 3/61).

TABLE-US-00003 TABLE 3 Average Light Moisture First Second Peak Average reflectance transmittance permeability peak peak intensity reflectance deviation deviation (g/m.sup.2 .Math. (°) (°) rate* (%) (% p) (% p) day) Example 1 25.6 46.6 0.058 1.13 0.04 0.01 11.13 Example 2 25.7 46.6 0.055 1.27 0.11 0.08 10.28 Example 3 25.8 46.5 0.068 1.11 0.07 0.03 12.31 Example 4 25.8 46.7 0.059 1.03 0.16 0.04 11.51 Example 5 25.7 46.8 0.034 1.58 0.05 0.07 10.95 Comparative 25.4 46.5 0.0055 1.15 0.31 0.29 11.33 Example 1 Comparative 25.6 46.6 0.0051 1.22 0.25 0.28 10.82 Example 2 Comparative 25.5 46.6 0.0054 1.0 0.28 0.3 11.18 Example 3 Comparative 25.7 46.5 0.0055 1.54 0.3 0.31 12.36 Example 4 *Peak strength rate: a rate (P2/P1) of the strength of a second peak(P2) to the strength of a first peak(P1)

[0165] According to the Table 3, the anti-reflective films of Examples 1 to 5 exhibited average reflectance deviation of 0.16% p or less, and light transmittance deviation of 0.08% p, and thus, it was confirmed that there was little difference in the average reflectance and light transmittance across the anti-reflective film. However, it was confirmed that the anti-reflective films of Comparative Examples 1 to 4 had remarkably high average reflectance deviations and light transmittance deviations, unlike the anti-reflective films of Examples 1 to 5.

PREPARATION EXAMPLE 3: PREPARATION OF A POLARIZER INCLUDING A SECOND HARD COATING LAYER FORMED ON ONE SIDE

[0166] (1) Preparation of a Coating Solution (A) for Forming a Second Hard Coating Layer

[0167] 28 g of trimethylolpropane triacrylate, 2 g of KBE-403, 0.1 g of initiator KIP-100f, and 0.06 g of a leveling agent (Tego wet 270) were uniformly mixed to prepare a coating solution (A) for forming a second hard coating layer.

[0168] (2) Preparation of a Polarizer Including a Second Hard Coating Layer Formed on One Side

[0169] On one side of a polyvinyl alcohol polarizer (thickness 25 um, Manufacturing Company: LG Chem.), the coating solution (A) for forming a second hard coating layer was applied to a thickness of 7 um, and UV of 500 mJ/cm.sup.2 was irradiated to the dried coating under nitrogen purging, thus preparing a polarizer including a second hard coating layer formed on one side.

EXAMPLES 6 TO 10 AND COMPARATIVE EXAMPLES 5 TO 8: PREPARATION OF POLARIZING PLATE

[0170] As described in the following Table 4, on the light transmitting substrate of the anti-reflective film respectively obtained in Examples 1 to 5 and Comparative Examples 1 to 4, the polarizer including a second hard coating layer formed on one side, obtained in the Preparation Example 3, was adhered with UV adhesive to prepare a polarizing plate. Specifically, the polarizing plate was prepared such that the light transmitting substrate of the anti-reflective film and the polarizer are in direct contact, and the prepared polarizing plate included a low refractive index layer, a hard coating layer, a light transmitting substrate, a polarizer, and a second hard coating layer sequentially stacked.

TABLE-US-00004 TABLE 4 Anti-reflective Polarizer having a second hard film coating layer formed on one side Example 6 Example 1 Preparation Example 3 Example 7 Example 2 Preparation Example 3 Example 8 Example 3 Preparation Example 3 Example 9 Example 4 Preparation Example 3 Example 10 Example 5 Preparation Example 3 Comparative Comparative Preparation Example 3 Example 5 Example 1 Comparative Comparative Preparation Example 3 Example 6 Example 2 Comparative Comparative Preparation Example 3 Example 7 Example 3 Comparative Comparative Preparation Example 3 Example 8 Example 4

[0171] Evaluation

[0172] 1. Evaluation of Average Reflectance Deviation and Light Transmittance Deviation

[0173] For the Examples 6 to 10 and Comparative Examples 5 to 8, average reflectance deviation and light transmittance deviation were measured by the method as explained above, and the results were shown in the following Table 5.

[0174] 2. Crack Property

[0175] Each polarizing plate of Examples 6 to 10 and Comparative Examples 5 to 8 was cut into a square having one side length of 10 cm, and joined to one side of glass for TV (width 12 cm, height, 12 cm, thickness 0.7 mm) to prepare a sample for evaluating thermal shock. Wherein, the polarizing plate was cut such that the MD direction of the polarizer is parallel to one side of square. The cut sample stood vertically in a thermal shock chamber, and the temperature was raised from a room temperature to 80° C. and left for 30 minutes, the temperature was lowered to −30° C. and left for 30 minutes, and then, the temperature was controlled to a room temperature, which was set as 1 cycle and repeated total 100 cycles. Thereafter, it was confirmed with naked eyes that cracks were generated between the polarizer of the sample and gaps were generated between the polarizer, the number of cracks having length of 1 cm or more was confirmed, and the results were described in the following Table 5.

TABLE-US-00005 TABLE 5 Average reflectance Light transmittance deviation (% p) deviation (% p) crack Example 6 0.05 0.03 0 Example 7 0.12 0.05 0 Example 8 0.05 0.04 0 Example 9 0.13 0.06 0 Example 10 0.04 0.05 0 Comparative 0.27 0.3 3 Example 5 Comparative 0.30 0.29 2 Example 6 Comparative 0.29 0.35 4 Example 7 Comparative 0.35 0.33 3 Example 8

[0176] According to Table 5, it was confirmed that the polarizing plates of Examples 6 to 10 have average reflectance deviations of 0.13% p or less, and light transmittance deviation of 0.06% p or less, and thus, there is little difference in the average reflectance and light transmittance across the polarizing plate, and there is no visibility deviation according to the region. However, the polarizing plates of Comparative Examples 5 to 8, unlike the polarizing plates of Examples 6 to 8, have remarkably high average reflectance deviations and light transmittance deviations, and thus, it can be expected that visibility deviation may significantly appear according to the region.

[0177] And, it was confirmed that in Examples 6 to 10 having low average reflectance and light transmittance deviations, cracks are not generated at all in 100 cycle repeated crack test. To the contrary, in the polarizing plates of Comparative Examples 5 to 8, cracks are generated.