Antireflection film

Abstract

The present invention relates to an antireflection film including a low refractive index layer and a hard coating layer, the low refractive index layer including: a binder resin containing a crosslinked polymer of a photopolymerizable compound and a polysilsesquioxane substituted with one or more reactive functional groups; and inorganic fine particles dispersed in the binder resin, wherein a 10-point average roughness (Rz) of the shape of irregularities on the surface of the low refractive index layer is 0.05 μm to 0.2 μm.

Claims

1. An antireflection film, comprising: a low refractive index layer and a hard coating layer, wherein the low refractive index layer includes a binder resin containing a crosslinked polymer of a photopolymerizable compound, a fluorine-based compound containing a photoreactive functional group and a polysilsesquioxane substituted with only one reactive functional group; and inorganic fine particles dispersed in e binder resin; wherein a 10-point average roughness (Rz) of the shape of irregularities on the surface of the low refractive index layer is 0.05 μm to 0.2 μm, wherein the fluorine-based compound containing a photoreactive functional group has a fluorine content of 1% by weight to 25% by weight and a silicon content of 0.1% by weight to 20% by weight, and wherein the inorganic fine particles include at least one selected from the group consisting of solid inorganic nanoparticles having a diameter of 0.5 to 100 nm, and hollow inorganic nanoparticles having a diameter of 1 to 200 nm.

2. The antireflection film of claim 1, wherein the 10-point average roughness (Rz) of the shape of irregularities on the surface of the low refractive index is a result measured using a non-contact surface measuring system of a 3D optical profiler.

3. The antireflection film of claim 1, wherein a weight ratio of the portion derived from the polysilsesquioxane substituted with only one reactive functional group to the portion derived from the photopolymerizable compound in the binder resin contained in the low refractive index layer is 0.005 to 0.50.

4. The antireflection film of claim 1, wherein the reactive functional group substituted on the polysilsesquioxane is a functional group selected from the group consisting of an alcohol, an amine, a carboxylic acid, an epoxide, an imide, a (meth)acrylate, a nitrile, a. norbornene, an olefin, a polyethylene glycol, a thiol, and a vinyl group.

5. The antireflection film of claim 1, wherein the polysilsesquioxane substituted with only one reactive functional group includes a polyhedral oligomeric silsesquioxane having a cage structure.

6. The antireflection film of claim 5, wherein silicon atoms of the polyhedral oligomeric polysilsesquioxane are substituted with a reactive or unreactive functional group, and only one silicon atom of the polyhedral oligomeric polysilsesquioxane is substituted with the reactive functional group.

7. The antireflection film of claim 1, wherein the photopolymerizable compound includes a monomer or an oligomer containing a (meth)acrylate or vinyl group.

8. The antireflection film of claim 1, wherein the photoreactive functional group contained in the fluorine-based compound is at least one selected from the group consisting of a (meth)acrylate group, an epoxide group, a vinyl group, and a thiol group.

9. The antireflection film of claim 1, wherein the fluorine-based compound containing the photoreactive functional group includes at least one selected from the group consisting of: i) an aliphatic compound or an aliphatic cyclic compound in which at least one photoreactive functional group is substituted and at least one fluorine is substituted on at least one carbon; ii) a heteroaliphatic compound or a heteroaliphatic cyclic compound in which at least one photoreactive functional group is substituted, at least one hydrogen is substituted with fluorine, and at least one carbon is substituted with silicon; iii) a polydialkylsiloxane-based polymer in which at least one photoreactive functional group is substituted and at least one fluorine is substituted on at least one silicon; and iv) a polyether compound in which at least one photoreactive functional group is substituted and at least one hydrogen is substituted with fluorine.

10. The antireflection film of claim 1, wherein the fluorine-based compound containing the photoreactive functional group has a weight-average molecular weight of 2000 to 200,000.

11. The antireflection film of claim 1, wherein the low refractive index layer has a thickness of 1 nm to 200 nm, and the hard coating layer has a thickness of 0.1 μm to 100 μm.

12. The antireflection film of claim 1, wherein the hard coating film comprises a binder resin containing a photopolymerizable resin and organic or inorganic fine particles dispersed in the binder resin wherein the organic fine particles have a particle diameter of 1 to 10 μm, and the inorganic particles have a particle diameter of 1 nm to 500 nm.

13. The antireflection film of claim 12, wherein the binder resin of the hard coating layer further includes a high molecular weight (co)polymer having a weight average molecular weight of 10,000 or more.

14. The antireflection film of claim 1, wherein the antireflection film has average reflectance of 5% or less in a visible light wavelength band region of 380 nm to 780 nm, as measured at an incident angle of 8 degrees.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

(1) The present invention will be described in more detail by way of examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention thereto.

Preparation Example

Preparation Example 1: Preparation of Hard Coating Film 1 (HD1)

(2) 13 g of pentaerythritol triacrylate, 10 g of a urethane-based acryl oligomer (306I, KYOEISHA Chemical), 10 g of a urethane-based acryl oligomer (306T, KYOEISHA Chemical), 20 g of isopropyl alcohol, 2 g of a photoinitiator (Irgacure 184, Ciba), and 0.5 g of a leveling agent (BYK 300) were homogeneously mixed, and then 2.3 g of acrylic-styrene copolymer resin fine particles with a refractive index of 1.555 (Techpolymer, volume average particle size: 3 μm, manufacturer: Sekisui Plastic) and 0.01 g of a nano-silica dispersion liquid (volume average particle size: about 12 nm, Optisol-LSM, Lancosa) were added thereto to prepare a hard coating composition.

(3) The hard coating composition thus obtained was coated onto a triacetyl cellulose film with a #10 Mayer bar, and dried at 90° C. for 1 minute.

(4) Ultraviolet rays of 150 mJ/cm.sup.2 were irradiated onto the dried product to prepare a hard coating film having a thickness of 6 μm.

Preparation Example 2: Preparation of Hard Coating Film 2 (HD2)

(5) 13 g of pentaerythritol triacrylate, 10 g of a urethane-based acryl oligomer (306I, KYOEISHA Chemical), 10 g of a photopolymerizable urethane-based acryl oligomer (MW 250,000, Daesung Chemical, 8BR-500), 20 g of isopropyl alcohol, 2 g of a photoinitiator (Irgacure 184, Ciba), and 0.5 g of a leveling agent (BYK 300) were homogeneously mixed, and then 1.3 g of acrylic-styrene copolymer resin fine particles with a refractive index of 1.555 (Techpolymer, volume average particle size: 2 μm, manufacturer: Sekisui Plastic), 1.3 g of acrylic-styrene copolymer resin fine particles with a refractive index of 1.525 (Techpolymer, volume average particle size: 2 μm, manufacturer: Sekisui Plastic), and 0.03 g of a nano-silica dispersion liquid (volume average particle size: about 12 nm, Optisol-LSM, Lancosa) were added thereto to prepare a hard coating composition.

(6) The hard coating composition thus obtained was coated onto a triacetyl cellulose film with a #10 Mayer bar, and dried at 90° C. for 1 minute.

(7) Ultraviolet rays of 150 mJ/cm.sup.2 were irradiated onto the dried product to prepare a hard coating film having a thickness of 6 μm.

Preparation Example 3: Preparation of Hard Coating Film 3 (HD3)

(8) 13 g of pentaerythritol triacrylate, 10 g of a urethane-based acryl oligomer (306I, KYOEISHA Chemical), 10 g of a photopolymerizable urethane-based acryl oligomer (MW 250,000, Daesung Chemical, 8BR-500), 20 g of isopropyl alcohol, 2 g of a photoinitiator (Irgacure 184, Ciba), and 0.5 g of a leveling agent (BYK 300) were homogeneously mixed, and then 1.0 g of acrylic-styrene copolymer resin fine particles with a refractive index of 1.555 (Techpolymer, volume average particle size: 2 μm, manufacturer: Sekisui Plastic), 0.3 g of crosslinked styrene resin spherical particles with a refractive index of 1.60 (Techpolymer, volume average particle size: 3.5 μm, manufacturer: Sekisui Plastic), and 0.03 g of a nano-silica dispersion liquid (volume average particle size: about 100 nm, X24-9600 A, Shin-Etsu) were added thereto to prepare a hard coating composition.

(9) The hard coating composition thus obtained was coated onto a triacetyl cellulose film with a #10 Mayer bar, and dried at 90° C. for 1 minute.

(10) Ultraviolet rays of 150 mJ/cm.sup.2 were irradiated onto the dried product to prepare a hard coating film having a thickness of 6 μm.

Preparation Example 4: Preparation of Hard Coating Film 4 (HD4)

(11) 30 g of pentaerythritol triacrylate, 2.5 g of a high molecular weight copolymer (BEAMSET 371, Arakawa Chemical Industries, Ltd., Epoxy Acrylate, molecular weight 40,000), 20 g of methyl ethyl ketone, 2 g of a photoinitiator (Irgacure 184, Ciba), and 0.5 g of a leveling agent (Tego wet 270) were homogeneously mixed, and then 2 g of acrylic-styrene copolymer resin fine particles with a refractive index of 1.544 (Techpolymer, volume average particle size: 2 μm, manufacturer: Sekisui Plastic) was added thereto to prepare a hard coating composition.

(12) The hard coating composition thus obtained was coated onto a triacetyl cellulose film with a #10 Mayer bar, and dried at 90° C. for 1 minute.

(13) Ultraviolet rays of 150 mJ/cm.sup.2 were irradiated onto the dried product to prepare a hard coating film having a thickness of 6 μm.

Preparation Example 5: Preparation of Hard Coating Film 5 (HD5)

(14) 15 g of pentaerythritol triacrylate, 10 g of a urethane-based acryl oligomer (306I, KYOEISHA Chemical), 30 g of methyl ethyl ketone, 30 g of toluene, 2 g of a photoinitiator (Irgacure 184, Ciba), and 0.5 g of a leveling agent (Tego 410) were homogeneously mixed, and then 1 g of crosslinked styrene resin spherical particles with a refractive index of 1.59 (volume average particle size: 3.5 μm, SX series, Soken) and 1 g of acrylic-styrene copolymer resin fine particles with a refractive index of 1.525 (Techpolymer, volume average particle size: about 3 μm, manufacturer: Sekisui Plastic) were added thereto to prepare a hard coating composition.

(15) The hard coating composition thus obtained was coated onto a triacetyl cellulose film with a #10 Mayer bar, and dried at 90° C. for 1 minute. Ultraviolet rays of 150 mJ/cm.sup.2 were irradiated onto the dried product to prepare a hard coating film having a thickness of 6 μm.

Preparation Example 6: Preparation of Hard Coating Film 6 (HD6)

(16) 30 g of pentaerythritol triacrylate, 2.5 g of a high molecular weight copolymer (BEAMSET 371, Arakawa Chemical Industries, Ltd., Epoxy Acrylate, molecular weight 40,000), 2 g of a photoinitiator (Irgacure 184, Ciba), 20 g of methyl ethyl ketone, and 0.5 g of a leveling agent (Tego wet 270) were homogeneously mixed, and then 2 g of acrylic-styrene copolymer resin fine particles with a refractive index of 1.525 (volume average particle size: 2 μm, manufacturer: Sekisui Plastic) and 0.1 g of a nano-silica dispersion liquid (volume average particle size: 12 nm, Optisol-LSM, Lancosa) were added thereto to prepare a hard coating composition.

(17) The hard coating composition thus obtained was coated onto a triacetyl cellulose film with a #10 Mayer bar, and dried at 90° C. for 1 minute.

(18) Ultraviolet rays of 150 mJ/cm.sup.2 were irradiated onto the dried product to prepare a hard coating film having a thickness of 4 μm.

Examples and Comparative Examples: Preparation of Antireflection Film

(19) (1) Preparation of a Photopolymerizable Coating Composition for Preparing a Low Reflective Index Layer

(20) The components shown in Table 1 below were mixed, and diluted in a solvent mixed with MIBK (methyl isobutyl ketone) and diacetone alcohol (DAA) at a weight ratio of 1:1 so that the solid content became 3% by weight.

(21) TABLE-US-00001 TABLE 1 (Unit: g) LR1 LR2 LR3 LR4 LR5 Hollow silica dispersion 220  30 20 30   6.7 liquid (THRULYA (THRULYA (THRULYA (THRULYA (MIBK-SD) 4320) 4320) 4320) 4320) rimethylolpropane 41  62 47 67 1 triacrylate (1H,1H,6H,6H- perfluoro-1,6- hexanediol diacrylate) olysilsesquioxane 6 (MA0701) 0 0 4 (MA0701) (AC-SQ-F) luorine-based   13.33    6.667 13.333 6.667    0.1001 compound containing photoreactive functional group RS907 Photoinitiator 5  5  5 5   0.25 (Irgacure-127, Ciba)

(22) 1) THRULYA 4320 (manufactured by Catalysts and Chemicals Ltd.): Hollow silica dispersion liquid (solid content of 20 wt % in MIBK solvent)

(23) 2) RS907 (manufactured by DIC): Fluorine-based compound containing a photoreactive functional group and containing a trace amount of silicon, diluted to a solid content of 30% by weight in MIBK solvent

(24) 3) MA0701: manufactured by Hybrid Plastics

(25) 4) AC-SQ-F: manufactured by Toagosei Co., Ltd. (silsesquioxane resin, functional group concentration 678 g/mol, inorganic fraction 15%, refractive index 1.39)

(26) (2) Preparation of a Low Reflective Index Layer and an Antireflection Film

(27) The photopolymerizable coating compositions each obtained from Table 1 were coated onto the hard coating films described in Table 2 below with a #3 Mayer bar, and dried at 60° C. for 1 minute.

(28) Then, ultraviolet rays of 180 mJ/cm.sup.2 were irradiated onto the dried product under a nitrogen purge to form a low refractive index layer having a thickness of 110 nm, thereby producing an antireflection film.

Experimental Example: Measurement of Physical Properties of Antireflection Film

(29) For the antireflection films obtained in the examples and Comparative examples, experiments of the following items were carried out.

(30) 1. Alkaline Pretreatment

(31) The antireflection films obtained in the examples and comparative examples were respectively immersed in an aqueous NaOH solution diluted to 10% with distilled water at 55° C. for 30 seconds, and washed by pouring water, followed by wiping off moisture.

(32) 2. Measurement of Average Reflectance and Color Coordinate Value (b*)

(33) For the antireflection films obtained in the above examples and comparative examples, the back of the film was subjected to a darkening process before and after pretreatment, and then the average reflectance and the color coordinate value (b*) in a wavelength region from 380 nm to 780 nm were measured by applying a 100 T mode of Solidspec 3700 (SHIMADZU).

(34) In the case of the color coordinate value (b*), the obtained average reflectance data was converted by a UV-2401PC program.

(35) 3. Measurement of Scratch Resistance

(36) Before and after the pretreatment, the surfaces of the antireflection films obtained in the examples and comparative examples were rubbed while applying a load to steel wool (#0000) and reciprocating ten times at a speed of 27 rpm.

(37) The scratch resistance was evaluated by confirming the maximum load at which a scratch of 1 cm or less observed with the naked eye was 1 or less.

(38) 4. Measurement of Surface Roughness

(39) The 10-point average roughness of the shape of irregularities on the surface of the antireflection films each obtained in the examples and comparative examples was measured using a white-light interference 3D optical profiler (model name: NewView 7300, Zygo).

(40) At this time, the area of 3.00*0.52 mm.sup.2 was measured under the zoom measurement condition where the magnification of the lens used was 10 times (10×) and 1 time (1×).

(41) Specifically, an antireflection film to be measured was placed on a sample stage in a flat state, images were obtained from an optical profiler, and the measurement was performed.

(42) At this time, the measurement was performed by setting the lateral length to 3 mm, 2 to 3 line profiles were obtained from the obtained images, and 10-point average roughness was calculated.

(43) 5. Haze Measurement

(44) For the antireflection films each obtained in the examples and comparative examples, the haze was measured at three places using HAZEMETER HM-150 equipment (manufactured by Murakami Color Research Laboratory) according to JIS K7105, and the average value was determined.

(45) (1) Total haze (Ha): surface haze (Hs)+internal haze (Hi)

(46) (2) The total haze is measured with respect to the haze of the antireflection film itself.

(47) (3) The internal haze: A planarization layer was coated at 8 μm on the surface of the alkali-treated antireflection film, and haze of the entire film was measured.

(48) (4) Alkali treatment: The antireflection films obtained in the examples and comparative examples were respectively immersed in an aqueous NaOH solution diluted to 10% with distilled water at 30° C. for 2 minutes, and washed by pouring water, followed by wiping off moisture. Then, they were dried in an oven at 50° C. for 1 minute.

(49) (5) Planarization layer coating: Pentaerythritol triacrylate and Ebecryl 220 (oligomers of SK Cytec) were mixed in a weight ratio of 6:1, diluted in a 2:1 (weight ratio) mixed solvent of methyl ethyl ketone and toluene so that the solid content became 60 wt %, coated in a dry film thickness of 8 μm using a wire bar, dried, and cured, and then irregularities of the surface were planarized.

(50) 6. Sharpness Measurement

(51) The sharpness of images was measured using ICM-1T from Suga Test Instruments.

(52) The comparison of the sharpness was performed in combination with the sharpness value from a slit of 0.125 mm and sharpness value from slits of 0.125 mm, 0.5 mm, 1.0 mm, and 2.0 mm.

(53) TABLE-US-00002 TABLE 2 Comparative Comparative Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 4 Example 1 Example 2 Example 3 Example 4 Example 5 Low refractive LR1 LR1 LR1 LR2 LR1 LR1 LR3 LR4 LR5 index layer Hard coating HD1 HD2 HD3 HD3 HD4 HD5 HD1 HD3 HD6 layer Average 1.20 1.15 1.16 2.1 1.18 1.2 1.16 2.1 1.1 reflectance (%) Scratch 350 350 350 600 350 350 150 500 300 resistance(g) Total haze 2.678 2.514 2.721 2.707 3.124 10.028 2.667 2.719 3.138 (Ha, %) Internal 2.527 2.329 2.607 2.589 2.761 7.347 2.528 2.581 2.515 haze (Hi, %) Hi/Ha (%) 94.36 92.64 95.81 95.64 88.38 73.265 94.788 94.925 80.146 Variation in 0.34 0.41 0.38 0.3 0.28 0.4 0.9 1.08 1.3 color coordinate value (b*) after alkali pretreatment 10-point average 0.141 0.127 0.167 0.171 0.473 1.121 0.146 0.168 0.632 roughness(Rz) Sharpness 91.6 90.9 92 91.2 74.1 64.8 92 90.9 71.2 (0.125 mm) Sharpness 376.9 374.7 380 377.8 326.1 303.1 377.9 378.3 322.7 (0.125 mm)

(54) As shown in Table 2 above, it was confirmed that the antireflection film of the examples exhibited relatively low average reflectance, and the variation in color coordinate after alkali treatment which was not very large, and furthermore, it had excellent scratch resistance as compared with the comparative examples.

(55) Specifically, while the 10-point average roughness (Rz) of the shape of irregularities on the surface of the low refractive index layer included in the antireflection film was 0.05 μm to 0.2 μm, the antireflection film had a variation in color coordinate values (b*) after alkali pretreatment in the range of 0.25 to 0.45.

(56) Further, it was confirmed that the antireflection film had total haze of 3% or less and internal haze of 2.7% or less, and the ratio of internal haze (Hi) to total haze (Ha) was 97% or less.

(57) On the other hand, from the result of the sharpness, the image is clearer as the value from a narrow slit is higher. As a result of the sharpness measurement on the antireflection film, when the sharpness from slit 0.125 mm was 80% or more and the sum of the sharpness values excluding the 0.25 mm slit value was 350% or more, it could be applied to a high resolution display. As shown in Table 2, the antireflection films of the examples showed that the sharpness from the slit of 0.125 mm and the sum of the sharpness satisfied the above-mentioned range.

(58) On the contrary, it was confirmed that the antireflection films of the comparative examples exhibited a relatively high variation in the color coordinate value or had low scratch resistance after alkali treatment.

(59) In addition, it was confirmed that the antireflection film of the comparative examples exhibited relatively high total haze (Ha) and internal haze (Hi) values, and relative low sharpness from the slit of 0.125 mm, thus exhibiting relatively low light transmittance and poor optical properties.