Anti-reflective film

Abstract

The present invention relates to an anti-reflective film exhibiting one or more peaks (q.sub.max) at a scattering vector of 0.0758 to 0.1256 nm.sup.−1, in a graph showing a log value of scattering intensity to a scattering vector defined in small-angle X-ray scattering.

Claims

1. An anti-reflective film exhibiting one or more peaks (q.sub.max) at a scattering vector of 0.0758 nm.sup.−1 or more, in a graph showing a log value of scattering intensity to a scattering vector defined in small-angle X-ray scattering, wherein the small-angle X-ray scattering is measured by irradiating X-rays of a wavelength of 0.63 to 1.54 Å to an anti-reflective film with a size of 1 cm*1 cm (width*length) at a distance of 4 m; wherein the scattering vector is defined as in the following Equation 1:
q=4π sin θ/λ  [Equation 1] wherein, in Equation 1, q is a scattering vector, θ is a ½ value of a scattering angle, and λ is a wavelength of irradiated X-rays, wherein the anti-reflective film comprises a hard coating layer and a low refractive index layer disposed on the hard coating layer, the low refractive index layer comprising a binder resin, and hollow inorganic nanoparticles and solid inorganic nanoparticles dispersed in the binder resin, wherein the low refractive index layer comprises a first layer comprising 70 vol % or more of the total volume of the solid inorganic nanoparticles and a second layer comprising 70 vol % or more of the total volume of the hollow inorganic nanoparticles, wherein the anti-reflective film comprising an interface between the hard coating layer and the low refractive index layer, wherein the first layer and the second layer are sequentially laminated from the interface, wherein the second layer is in contact with the first layer, wherein the interface between the first layer and the second layer comprises the solid inorganic nanoparticles and the hollow inorganic nanoparticles, wherein the second layer has polarization ellipticity measured by ellipsometry using a Cauchy model represented by the following General Formula 1 in which A is 1.0 to 1.50, B is 0 to 0.007, and C is 0 to 1*10.sup.−3: $\begin{array}{cc}n\left(\lambda \right)=A+\frac{B}{{\lambda }^2}+\frac{C}{{\lambda }^4}& \left[\mathrm{General}\mathrm{Formula}1\right]\end{array}$ in the General Formula 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.

2. The anti-reflective film according to claim 1, wherein the anti-reflective film exhibits mean reflectance of 1.5% or less in a visible light wavelength region of 380 to 780 nm.

3. The anti-reflective film according to claim 1, wherein the solid inorganic nanoparticles have a density of 2.00 g/cm to 4.00 g/cm, and the hollow inorganic nanoparticles have a density of 1.50 g/cm to 3.50 g/cm.

4. The anti-reflective film according to claim 1, wherein the first layer has polarization ellipticity measured by ellipsometry using a Cauchy model of the General Formula 1 in which A is 1.0 to 1.65, B is 0.0010 to 0.0350, and C is 0 to 1*10.sup.−3.

5. The anti-reflective film according to claim 1, wherein the first layer has a refractive index of 1.420 to 1.600 at 550 nm, and the second layer has a refractive index of 1.200 to 1.410 at 550 nm.

6. The anti-reflective film according to claim 1, wherein the first layer has a thickness of 1 nm to 50 nm, and the second layer has a thickness of 5 nm to 300 nm.

7. The anti-reflective film according to claim 6, 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.

8. The anti-reflective film according to claim 1, wherein the solid inorganic nanoparticles have a density at least 0.50 g/cm greater than density of the hollow inorganic nanoparticles.

9. The anti-reflective film according to claim 1, wherein the solid inorganic nanoparticles and the hollow inorganic nanoparticles respectively contain one or more reactive functional groups selected from the group consisting of a (meth)acrylate group, an epoxide group, a vinyl group, and a thiol group on the surface thereof.

10. The anti-reflective film according to claim 1, wherein the binder resin included in the low refractive index layer comprises a (co)polymer of photopolymerizable compounds and a cross-linked (co)polymer of fluorine-containing compounds comprising photoreactive functional groups.

11. The anti-reflective film according to claim 10, wherein the low refractive index layer comprises, based on 100 parts by weight of the (co)polymer of photopolymerizable compounds, 10 to 400 parts by weight of the hollow inorganic nanoparticles and 10 to 400 parts by weight of the solid inorganic nanoparticles.

12. The anti-reflective film according to claim 10, wherein the fluorine-containing compounds comprising photoreactive functional groups respectively have a weight average molecular weight of 2000 to 200,000.

13. The anti-reflective film according to claim 10, wherein the binder resin comprises, based on 100 parts by weight of the (co)polymer of photopolymerizable compounds, 20 to 300 parts by weight of the fluorine-containing compounds comprising photoreactive functional groups.

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

15. The anti-reflective film according to claim 14, wherein the organic fine particles have a particle diameter of 1 to 10 μm, and the inorganic particles have a particle diameter of 1 to 500 nm.

16. The anti-reflective film according to claim 1, exhibiting one or more peaks (q.sub.max) at a scattering vector of 0.0758 to 0.1256 nm.sup.−1, in a graph showing a log value of scattering intensity to a scattering vector defined in small-angle X-ray scattering.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows the cross-sectional TEM image of the anti-reflective film of Example 1.

(2) FIG. 2 shows the cross-sectional TEM image of the anti-reflective film of Example 2.

(3) FIG. 3 shows the cross-sectional TEM image of the anti-reflective film of Example 3.

(4) FIG. 4 shows the cross-sectional TEM image of the anti-reflective film of Example 4.

(5) FIG. 5 shows the cross-sectional TEM image of the anti-reflective film of Example 5.

(6) FIG. 6 shows the cross-sectional TEM image of the anti-reflective film of Example 6.

(7) FIG. 7 shows the cross-sectional TEM image of the anti-reflective film of Comparative Example 1.

(8) FIG. 8 shows the cross-sectional TEM image of the anti-reflective film of Comparative Example 2.

(9) FIG. 9 shows the cross-sectional TEM image of the anti-reflective film of Comparative Example 3.

(10) FIG. 10 is a graph showing the log value of scattering intensity to a scattering vector defined in small angle scattering obtained by X-ray irradiation of the anti-reflective film of Example 1.

(11) FIG. 11 is a graph showing the log value of scattering intensity to a scattering vector defined in small angle scattering obtained by X-ray irradiation of the anti-reflective film of Example 2.

(12) FIG. 12 is a graph showing the log value of scattering intensity to a scattering vector defined in small angle scattering obtained by X-ray irradiation of the anti-reflective film of Example 3.

(13) FIG. 13 is a graph showing the log value of scattering intensity to a scattering vector defined in small angle scattering obtained by X-ray irradiation of the anti-reflective film of Example 4.

(14) FIG. 14 is a graph showing the log value of scattering intensity to a scattering vector defined in small angle scattering obtained by X-ray irradiation of the anti-reflective film of Example 5.

(15) FIG. 15 is a graph showing the log value of scattering intensity to a scattering vector defined in small angle scattering obtained by X-ray irradiation of the anti-reflective film of Example 6.

(16) FIG. 16 is a graph showing the log value of scattering intensity to a scattering vector defined in small angle scattering obtained by X-ray irradiation of the anti-reflective film of Comparative Example 1.

(17) FIG. 17 is a graph showing the log value of scattering intensity to a scattering vector defined in small angle scattering obtained by X-ray irradiation of the anti-reflective film of Comparative Example 2.

(18) FIG. 18 is a graph showing the log value of scattering intensity to a scattering vector defined in small angle scattering obtained by X-ray irradiation of the anti-reflective film of Comparative Example 3.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(19) The present invention will be explained in detail in the following examples. However, these examples are presented only as the illustrations of the present invention, and the scope of the present invention is not limited thereby.

Preparation Example

(20) Preparation Example: Preparation of a Hard Coating Film

(21) A salt type of antistatic hard coating liquid manufactured by KYOEISHA Company (solid content 50 wt %, product name: LJD-1000) was coated on a triacetyl cellulose film with a #10 Meyer bar and dried at 90° C. for 1 min, and then irradiated by UV at 150 mJ/cm.sup.2 to prepare a hard coating film with a thickness of about 5 to 6 μm.

Examples 1 to 5: Preparation of an Anti-Reflective Film

Examples 1 to 4

(22) (1) Preparation of a Photocurable Coating Composition for Forming a Low Refractive Layer

(23) Based on 100 parts by weight of pentaerythritol triacrylate (PETA), 281 parts by weight of hollow silica nanoparticles (diameter: about 50 to 60 nm, density: 1.96 g/cm.sup.3, manufactured by JSC Catalysts and Chemicals Ltd.), 63 parts by weight of solid silica nanoparticles (diameter: about 12 nm, density: 2.65 g/cm.sup.3), 131 parts by weight of a first fluorine-containing compound (X-71-1203M, ShinEtsu Chemical Co., Ltd.), 19 parts by weight of a second fluorine-containing compound (RS-537, DIC Corporation), and 31 parts by weight of an initiator (Irgacure 127, Ciba Corporation) were diluted in a MIBK (methyl isobutyl ketone) solvent such that the solid concentration became 3 wt %.

(24) (2) Preparation of a Low Refractive Layer and an Anti-Reflective Film

(25) On the hard coating film of the preparation example, the above-obtained photocurable coating composition was coated to a thickness of about 110 to 120 nm with a #4 Meyer bar, and dried and cured using the temperature and time as described in the following Table 1. During the curing, UV at 252 mJ/cm.sup.2 was irradiated to the dried coating under nitrogen purging.

Example 5

(26) (1) Preparation of a Photocurable Coating Composition for Forming a Low Refractive Layer

(27) Based on 100 parts by weight of trimethylolpropane triacrylate (TMPTA), 268 parts by weight of hollow silica nanoparticles (diameter: about 50 to 60 nm, density: 1.96 g/cm.sup.3, manufactured by JSC Catalysts and Chemicals Ltd.), 55 parts by weight of solid silica nanoparticles (diameter: about 12 nm, density: 2.65 g/cm.sup.3), 144 parts by weight of a first fluorine-containing compound (X-71-1203M, ShinEtsu Chemical Co., Ltd.), 21 parts by weight of a second fluorine-containing compound (RS-537, DIC Corporation), and 31 parts by weight of an initiator (Irgacure 127, Ciba Corporation) were diluted in a MIBK (methyl isobutyl ketone) solvent such that the solid concentration became 3 wt %.

(28) (2) Preparation of a Low Refractive Layer and an Anti-Reflective Film

(29) On the hard coating film of the preparation example, the above-obtained photocurable coating composition was coated to a thickness of about 110 to 120 nm with a #4 Meyer bar, and dried and cured using the temperature and time as described in the following Table 1. During the curing, UV at 252 mJ/cm.sup.2 was irradiated to the dried coating under nitrogen purging.

(30) TABLE-US-00001 TABLE 1 Drying temperature Drying time Example 1 40° C. 1 min Example 2 60° C. 1 min Example 3 80° C. 1 min Example 4 60° C. 2 min Example 5 60° C. 3 min

Example 6

(31) (1) Preparation of a Hard Coating Layer (HD2)

(32) 30 g of pentaerythritol triacrylate, 2.5 g of a high molecular weight copolymer (BEAMSET 371, Arakawa Co. Ltd., Epoxy Acrylate, molecular weight 40,000), 20 g of methyl ethyl ketone, and 0.5 g of a leveling agent (Tego Wet 270) were uniformly mixed, and then 2 g of an acryl-styrene copolymer (volume average particle diameter: 2 μm, Manufacturing Company: Sekisui Plastic) with a refractive index of 1.525 was added as fine particles to prepare a hard coating composition.

(33) The above-obtained hard coating composition was coated on a triacetyl cellulose film with a #10 Meyer bar and dried at 90° C. for 1 min. The dried coating was irradiated by UV at 150 mJ/cm.sup.2 to prepare a hard coating layer with a thickness of 5 μm.

(34) (2) Preparation of a Low Refractive Layer and an Anti-Reflective Film

(35) Based on 100 parts by weight of pentaerythritol triacrylate (PETA), 135 parts by weight of hollow silica nanoparticles (diameter: about 50 to 60 nm, density: 1.96 g/cm.sup.3, manufactured by JSC Catalysts and Chemicals Ltd.), 88 parts by weight of solid silica nanoparticles (diameter: about 12 nm, density: 2.65 g/cm.sup.3), 38 parts by weight of a first fluorine-containing compound (X-71-1203M, ShinEtsu Chemical Co., Ltd.), 11 parts by weight of a second fluorine-containing compound (RS-537, DIC Corporation), and 7 parts by weight of an initiator (Irgacure 127, Ciba Corporation) were diluted in a mixed solvent of MIBK (methyl isobutyl ketone):diacetone alcohol (DAA):isopropyl alcohol at a weight ratio of 3:3:4 such that the solid concentration became 3 wt %, thus preparing a photocurable coating composition for forming a low refractive layer.

(36) On the above-prepared hard coating film (HD2), the above-obtained photocurable coating composition for forming a low refractive layer was coated to a thickness of about 110 to 120 nm with a #4 Meyer bar, and dried and cured at a temperature of 60° C. for 1 min. During the curing, UV at 252 mJ/cm.sup.2 was irradiated to the dried coating under nitrogen purging.

Comparative Examples: Preparation of an Anti-Reflective Film

Comparative Example 1

(37) An anti-reflective film was prepared by the same method as in Example 1, except that the photocurable coating composition for forming a low refractive layer was applied and dried at room temperature (25° C.).

Comparative Example 2

(38) A photocurable coating composition for forming a low refractive layer was prepared by the same method as in Example 1, except that 63 parts by weight of the solid silica nanoparticles used in Example 1 were replaced by 63 parts by weight of pentaerythritol triacrylate (PETA), and an anti-reflective layer was prepared by the same method as in Example 1.

Comparative Example 3

(39) An anti-reflective film was prepared by the same method as in Example 5, except that the photocurable coating composition for forming a low refractive layer was applied and dried at 140° C.

Experimental Example: Measurement of the Properties of Anti-Reflective Films

(40) For the anti-reflective films obtained in the examples and comparative examples, the following experiments were conducted.

(41) 1. Measurement of Mean Reflectance of an Anti-Reflective Film

(42) The mean reflectances of the anti-reflective films of the examples and comparative examples at a visible light region (380 to 780 nm) were measured using Solidspec 3700 (SHIMADZU).

(43) 2. Measurement of Anti-Pollution Property

(44) On the surface of the anti-reflective films obtained in the examples and comparative examples, straight lines with a length of 5 cm were drawn with a black felt pen, and rubbed with a clean wiper, and the number of rubbing times at which the lines were erased was confirmed to measure the anti-pollution property.

(45) <Measurement Standard>

(46) ◯: The number of rubbing times at which the lines are erased is 10 or less

(47) Δ: The number of rubbing times at which the lines are erased is 11 to 20

(48) X: The number of rubbing times at which the lines are erased is greater than 20

(49) 3. Measurement of Scratch Resistance

(50) While steel wool was loaded and allowed to go back and forth 10 times at 27 rpm, the surfaces of the anti-reflective films obtained in the examples and comparative examples were rubbed. The maximum load under which a scratch of 1 cm or less is observed as one or less with the unaided eye, was measured.

(51) 4. Measurement of Refractive Index

(52) For the phase-separated regions of the low refractive layers obtained in the examples, refractive indexes at 550 nm were calculated using elliptic polarization at a wavelength of 380 nm to 1000 nm and using a Cauchy model.

(53) Specifically, for each low refractive layer obtained in the examples, using an apparatus of J. A. Woollam Co. M-2000, a 70° incidence angle was applied and linear polarization was measured at a wavelength range of 380 to 1000 nm. The measured ellipsometry data (ψ,Δ) was fitted to a Cauchy model of the following Equation 1 for Layer 1 and Layer 2 of the low refractive layer such that MSE became 3 or less, using Complete EASE software.

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

(55) In Equation 1, n(λ) is a refractive index at a λ wavelength, λ is a range of 300 to 1800 nm, and A, B, and C are Cauchy parameters.

(56) 5. Measurement of Scattering Intensity According to Scattering Vector in Small Angle X-Ray Scattering

(57) To a specimen of 1 cm.sup.−1 cm (width*length) obtained from each anti-reflective film of the examples and comparative examples, X-rays of a wavelength of 1.54 Å were irradiated at a distance of 4 m, thus measuring the scattering vector and scattering intensity.

(58) Specifically, scattering intensity according to the scattering vector (q) was measured by transmitting X-rays through the specimen at a 4 C beam line of a Pohang Accelerator. More specifically, small angle scattering measurement was conducted by placing the specimen at a location about 4 m away from a detector and sending X-rays thereto, using X-rays with a vertical size of 0.023 mm and a horizontal size of 0.3 mm, and using 2D mar CCD as a detector. The scattered 2D diffraction pattern was obtained as an image, which was converted into scattering intensity according to the scattering vector (q) through calibration using a sample-to-detector distance obtained through a standard sample, and a circular average.
q=4π sin θ/λ  [Equation 1]

(59) In Equation 1, q is a scattering vector, θ is a ½ value of a scattering angle, and λ is the wavelength of irradiated X-rays.

(60) Based on the above measurement results, a scattering vector value at which a first peak appears in a graph showing the log value of scattering intensity according to the scattering vector defined in small angle X-ray scattering, was calculated.

(61) TABLE-US-00002 TABLE 2 Whether or Mean Scratch Anti- not phase reflectance resistance pollution separation q.sub.max (%) (g) property occurs (nm.sup.−1) Example 1 0.63 500 ◯ ◯ 0.12 Example 2 0.62 500 ◯ ◯ 0.121 Example 3 0.67 500 ◯ ◯ 0.119 Example 4 0.64 500 ◯ ◯ 0.12 Example 5 0.65 500 ◯ ◯ 0.12 Example 6 0.67 500 ◯ ◯ 0.106 Comparative 0.78 150 X X 0.0739 Example 1 Comparative 0.8 200 Δ X 0.127 Example 2 Comparative 0.75 200 X X 0.0722 Example 3

(62) TABLE-US-00003 TABLE 3 Example4 Refractive index Example 1 Example 2 Example 3 4 Example 5 Example 6 Region 1 1.502 1.505 1.498 1.491 1.511 1.505 Region 2 1.35 1.349 1.321 1.346 1.211 1.375

(63) As confirmed by Table 2 and FIGS. 10 to 15, the anti-reflective films of Examples 1 to 6 exhibit one or more peaks (q.sub.max) at a scattering vector of 0.0758 to 0.1256 nm.sup.−1, in a graph showing the log value of scattering intensity according to a scattering vector defined in small-angle X-ray scattering, and as shown in Table 2, the anti-reflective films of Examples 1 to 6 can simultaneously realize high scratch resistance and anti-pollution properties while exhibiting low reflectance of 0.70% or less in a visible light region.

(64) As shown in FIGS. 1 to 6, it is confirmed that in the low refractive layer of the anti-reflective films of Examples 1 to 6, hollow inorganic nanoparticles and solid inorganic nanoparticles are phase separated, most of the solid inorganic nanoparticles exist near the interface between a hard coating layer of the anti-reflective film and the low refractive layer, and most of the hollow inorganic nanoparticles exist at locations far from the hard coating layer.

(65) As shown in Table 3, it is confirmed that the first region and the second region that are distinguished by the phase separation of the hollow inorganic nanoparticles and the solid inorganic nanoparticles in the low refractive layer of the examples exhibit different ranges of refractive indexes, and specifically, the first region where solid inorganic nanoparticles are mainly distributed exhibits a refractive index of 1.420 or more, and the second region where hollow inorganic nanoparticles are mainly distributed exhibits a refractive index of 1.400 or less.

(66) To the contrary, as confirmed by Table 2 and FIGS. 16 to 18, in the graphs showing the log value of scattering intensity according to a scattering vector defined in small angle scattering by the X-ray irradiation of the anti-reflective films of Comparative Examples 1 to 3, a peak does not appear at a scattering vector range of 0.0758 to 0.1256 nm.sup.−1, and such anti-reflective films of Comparative Examples 1 to 3 respectively exhibit low scratch resistance and an anti-pollution property as well as relatively high reflectance.

(67) Further, as shown in FIGS. 7 and 9, it is confirmed that in the low refractive layers of the anti-reflective films of Comparative Examples 1 to 3, hollow inorganic nanoparticles and solid inorganic nanoparticles mixedly exist without phase separation.