Antireflection film

Abstract

The present invention relates to an antireflection film which exhibits one extremum at a thickness of 35 nm to 55 nm from the surface and exhibiting one extremum at a thickness of 85 nm to 105 nm from the surface in a graph showing the result of Fourier transform analysis for the result of X-ray reflectivity measurement using CuK-alpha rays.

Claims

1. An antireflection film comprising a hard coating layer, and a low refractive index layer disposed on the hard coating layer, the low refractive index layer containing a binder resin, and hollow inorganic nanoparticles and solid inorganic nanoparticles dispersed in the binder resin, the low refractive index layer exhibiting one extremum at a thickness of 35 nm to 55 nm and another extremum at a thickness of 85 nm to 105 nm, in a graph showing a result of Fourier transform analysis for X-ray reflectivity measurement using CuK-alpha rays, wherein each of the thickness of 35 nm to 55 nm and the thickness of 85 nm to 105 nm is a thickness from a surface of the low refractive index layer, wherein 70% by volume or more of the entire solid inorganic nanoparticles are present within 50% of the total thickness of the low refractive index layer from the interface between the hard coating layer and the low refractive index layer.

2. The antireflection film of claim 1, wherein the graph showing the result of Fourier transform analysis for X-ray reflectivity measurement using CuK-alpha rays represents a Fourier transform magnitude of y-axis relative to the film thickness from a surface of the low refractive index layer of x-axis.

3. The antireflection film of claim 2, wherein the X-ray reflectivity measurement using CuK-alpha rays is performed for an antireflection film having a size of 1 cm*1 cm (width*length) using CuK-alpha rays having a wavelength of 1.5418 .

4. The antireflection film of claim 1, wherein the X-ray reflectivity measurement using CuK-alpha rays is performed for an antireflection film having a size of 1 cm*1 cm (width*length) using CuK-alpha rays having a wavelength of 1.5418 .

5. The antireflection film of claim 1, wherein 30% by volume or more of the entire hollow inorganic nanoparticles are present at a greater distance in the thickness direction of the low refractive index layer from the interface between the hard coating layer and the low refractive index layer, compared to the solid inorganic nanoparticles.

6. The antireflection film of claim 1, wherein 70% by volume or more of the entire solid inorganic nanoparticles are present within 30% of the total thickness of the low refractive index layer from the interface between the hard coating layer and the low refractive index layer.

7. The antireflection film of claim 6, wherein 70% by volume or more of the entire hollow inorganic nanoparticles are present in a region exceeding 30% of the total thickness of the low refractive index layer from the interface between the hard coating layer and the low refractive index layer.

8. The antireflection film of claim 1, wherein the low refractive index layer includes a first layer containing 70% by volume or more of the entire solid inorganic nanoparticles and a second layer containing 70% by volume or more of the entire hollow inorganic nanoparticles, and the first layer is located closer to the interface between the hard coating layer and the low refractive index layer, compared to the second layer.

9. The antireflection film of claim 8, wherein 70% or more by volume of the entire solid inorganic nanoparticles are present within 50% of the total thickness of the low refractive index layer from the interface between the hard coating layer and the low refractive index layer.

10. The antireflection film of claim 1, wherein the solid inorganic nanoparticles have a higher density by 0.50 g/m.sup.3 or more compared to the hollow inorganic nanoparticles.

11. The antireflection film of claim 1, wherein each of the solid inorganic nanoparticles and the hollow inorganic nanoparticles has on the surface thereof at least one reactive functional group selected from the group consisting of a (meth)acrylate group, an epoxide group, a vinyl group, and a thiol group.

12. The antireflection film of claim 1, wherein the binder resin contained in the low refractive index layer may include a crosslinked (co)polymer between a (co)polymer of a photopolymerizable compound and a fluorine-containing compound containing a photoreactive functional group.

13. The antireflection film of claim 12, wherein the low refractive index layer includes 10 to 400 parts by weight of the hollow inorganic nanoparticles and 10 to 400 parts by weight of the solid inorganic nanoparticles, relative to 100 parts by weight of the (co)polymer of the photopolymerizable compound.

14. The antireflection film of claim 12, wherein each of the fluorine-containing compounds containing the photoreactive functional group has a weight average molecular weight of 2000 to 200,000.

15. The antireflection film of claim 12, wherein the binder resin includes 20 to 300 parts by weight of the fluorine-containing compound containing the photoreactive functional group based on 100 parts by weight of the (co)copolymer of the photopolymerizable compound.

16. The antireflection film of claim 1, wherein the hard coating layer includes a binder resin containing a photocurable resin, and organic or inorganic fine particles dispersed in the binder resin.

17. The antireflection film of claim 16, wherein the organic fine particles have a particle diameter of 1 to 10 m, and the inorganic fine particles have a particle diameter of 1 nm to 500 nm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a cross-sectional TEM photograph of the antireflection film of Example 1.

(2) FIG. 2 shows a cross-sectional TEM photograph of the antireflection film of Example 2.

(3) FIG. 3 shows a cross-sectional TEM photograph of the antireflection film of Example 3.

(4) FIG. 4 shows a cross-sectional TEM photograph of the antireflection film of Example 4.

(5) FIG. 5 shows a cross-sectional TEM photograph of the antireflection film of Example 5.

(6) FIG. 6 shows a cross-sectional TEM photograph of the antireflection film of Example 6.

(7) FIG. 7 shows a cross-sectional TEM photograph of the antireflection film of Comparative Example 1.

(8) FIG. 8 shows a cross-sectional TEM photograph of the antireflection film of Comparative Example 2.

(9) FIG. 9 shows a cross-sectional TEM photograph of the antireflection film of Comparative Example 3.

(10) FIG. 10 is a graph showing the result of Fourier transform analysis for the result of X-ray reflectivity measurement using CuK-alpha rays for the antireflection film of Example 1.

(11) FIG. 11 is a graph showing the result of Fourier transform analysis for the result of X-ray reflectivity measurement using CuK-alpha rays for the antireflection film of Example 2.

(12) FIG. 12 is a graph showing the result of Fourier transform analysis for the result of X-ray reflectivity measurement using Cu-K rays for the antireflection film of Example 3.

(13) FIG. 13 is a graph showing the result of Fourier transform analysis for the result of X-ray reflectivity measurement using CuK-alpha rays for the antireflection film of Example 4.

(14) FIG. 14 is a graph showing the result of Fourier transform analysis for the result of X-ray reflectivity measurement using CuK-alpha rays for the antireflection film of Example 4.

(15) FIG. 15 is a graph showing the result of Fourier transform analysis for the result of X-ray reflectivity measurement using CuK-alpha rays for the antireflection film of Example 6.

(16) FIG. 16 is a graph showing the result of Fourier transform analysis for the result of X-ray reflectivity measurement using CuK-alpha rays for the antireflection film of Comparative Example 1.

(17) FIG. 17 is a graph showing the result of Fourier transform analysis for the result of X-ray reflectivity measurement using CuK-alpha rays for the antireflection film of Comparative Example 2.

(18) FIG. 18 is a graph showing the result of Fourier transform analysis for the result of X-ray reflectivity measurement using CuK-alpha rays for the antireflection film of Comparative Example 2.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(19) The present invention will be described in more detail by way of examples.

(20) 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: Preparation of Hard Coating Layer

(21) A salt type of antistatic hard coating solution (manufactured by KYOEISHA Chemical, solid content: 50 wt %, product name: LJD-1000) was coated onto triacetyl cellulose film with a #10 Meyer bar, dried at 90 C. for 1 minute, and then irradiated with ultraviolet light of 150 mJ/cm.sup.2 to prepare a hard coating film having a thickness of about 5 to 6 m.

Examples 1 to 5: Preparation of Antireflection Film

Examples 1 to 4

(22) (1) Preparation of a Photocurable Coating Composition for Preparing a Low Refractive Index 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 Catalyst and Chemicals), 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, Shin-Etsu Chemical), 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) were diluted in MIBK (methyl isobutyl ketone) solvent so that the solid content concentration became 3 wt %.

(24) (2) Preparation of Low Refractive Index Layer and Antireflection Film

(25) The photocurable coating composition obtained as described above was coated onto the hard coating film of the preparation example in a thickness of about 110 to 120 nm with a #4 Meyer bar, and dried and cured at the temperature and time shown in Table 1 below.

(26) At the time of curing, ultraviolet light of 252 mJ/cm.sup.2 was irradiated to the dried coating under a nitrogen purge.

Example 5

(27) (1) Preparation of a Photocurable Coating Composition for Preparing a Low Refractive Index Layer

(28) 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 Catalyst and Chemicals), 55 parts by weight of solid silica nanoparticles (diameter: about 12 nm, density: 2.65 g/cm), 144 parts by weight of a first fluorine-containing compound (X-71-1203M, Shin-Etsu Chemical), 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) were diluted in MIBK (methyl isobutyl ketone) solvent so that the solid content concentration became 3 wt %.

(29) (2) Preparation of Low Refractive Index Layer and Antireflection Film

(30) The photocurable coating composition obtained as described above was coated onto the hard coating film of the preparation example in a thickness of about 110 to 120 nm with a #4 Meyer bar, and dried and cured at the temperature and time shown in Table 1 below. At the time of curing, ultraviolet light of 252 mJ/cm.sup.2 was irradiated to the dried coating under a nitrogen purge.

(31) 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

(32) (1) Preparation of Hard Coating Layer (HD2)

(33) 30 g of pentaerythritol triacrylate, 2.5 g of a high molecular weight copolymer (BEAMSET 371, Arakawa, Epoxy Acrylate, molecular weight: 40,000), 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 an acrylic-styrene copolymer (volume average particle diameter: 2 m, manufacturer: Sekisui Plastic) as fine particles having a refractive index of 1.525 was added to prepare a hard coating composition.

(34) The hard coating composition thus obtained was coated onto a triacetyl cellulose film with a #10 Meyer bar and dried at 90 C. for 1 minute. The ultraviolet light of 150 mJ/cm.sup.2 was irradiated to the dried product to prepare a hard coating layer having a thickness of 5 m.

(35) (2) Preparation of Low Refractive Index Layer and Antireflection Film

(36) 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 Catalyst and Chemicals), 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, Shin-Etsu Chemical), 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) were diluted in a 3:3:4 (weight ratio) mixed solvent of methyl isobutyl ketone (MIBK)/diacetone alcohol (DAA)/isopropyl alcohol so that the solid content concentration became 3 wt %.

(37) The photocurable coating composition obtained as described above was coated onto the hard coating layer (HD2) prepared above in 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 minute.

(38) At the time of curing, ultraviolet light of 252 mJ/cm.sup.2 was irradiated to the dried coating under a nitrogen purge.

Comparative Example: Preparation of Antireflection Film

Comparative Example 1

(39) An antireflection film was prepared in the same manner as in Example 1, except that the photocurable coating composition for preparing the low reflective index layer was coated and dried at room temperature (25 C.).

Comparative Example 2

(40) Except that 63 parts by weight of solid silica nanoparticles used in Example 1 were replaced with 63 parts by weight of pentaerythritol triacrylate (PETA), a photocurable coating composition for preparing the solid silica nanoparticles was prepared in the same manner as in Example 1 and an antireflection film was prepared in the same manner as in Example 1.

Comparative Example 3

(41) An antireflection film was prepared in the same manner as in Example 5, except that the photocurable coating composition for preparing the low reflective index layer was coated and then dried at a temperature of about 140 C.

Experimental Examples: Measurement of Physical Properties of Antireflection Films

(42) The following experiments were conducted for the antireflection films obtained in examples and comparative examples.

(43) 1. Measurement of Reflectivity of Antireflection Film

(44) The average reflectivity of the antireflection films obtained in the examples and comparative examples showing in a visible light region (380 to 780 nm) was measured using a Solidspec 3700 (SHIMADZU) apparatus.

(45) 2. Measurement of Antifouling Property

(46) A straight line with a length of 5 cm was drawn with a black marker on the surface of the antireflection films obtained in the examples and comparative examples. Then, the antifouling property was measured by confirming the number of times of erasing when rubbed with a poly wiper.

(47) <Measurement Standard>

(48) O: Erase when rubbing 10 times or less

(49) : Erase when rubbing 11 to 20 times

(50) X: Erase when rubbing 20 times or more

(51) 3. Measurement of Scratch Resistance

(52) The surfaces of the antireflection films obtained in the examples and comparative examples were rubbed while applying a load to steel wool and reciprocating ten times at a speed of 27 rpm.

(53) The maximum load at which one or less scratches with a size of 1 cm or less were generated, as observed with the naked eye, was measured.

(54) 4. Confirmation of Phase Separation

(55) In the cross-section of the antireflection film shown in FIGS. 1 to 7, it was determined that phase separation occurred when 70% by volume or more of the solid inorganic nanoparticles in the used solid inorganic nanoparticles (solid silica nanoparticles) were present within 30 nm from the hard coating layer.

(56) 5. Measurement of Reflective Index

(57) Using elliptically polarized light and the Cauchy model measured at wavelengths of 380 nm to 1000 nm for the phase separated region of the low refractive index layers obtained in the examples, the refractive index at 550 nm was calculated.

(58) Specifically, the ellipsometry was measured for the low refractive index layer obtained in each of the examples at an incidence angle of 70 over a wavelength range of 380 nm to 1000 nm by using a J. A. Woollam Co. M-2000 apparatus.

(59) The measured ellipsometry data (, ) was fitted to a Cauchy model of the following General Formula 1 using Complete EASE software for the first and second layers of the low refractive index layer so that MSE became 35 or less.

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

(61) In the above General Formula 1, n() is a refractive index at a wavelength , is in a range of 300 nm to 1800 nm, and A, B, and C are Cauchy parameters.

(62) 6. Fourier Transform Analysis for the Result of X-Ray Reflectivity Measurement Using CuK-Alpha Rays

(63) The X-ray reflectivity was measured by irradiating CuK-alpha rays having a wavelength of 1.5418 for an antireflection film with a size of 1 cm*1 cm (width*length).

(64) Specifically, the apparatus used was a PANalytical X'Pert Pro MRD XRD, and a voltage of 45 kV and a current of 40 mA were applied.

(65) The optics used are as follows. Incident beam optic: Primary mirror, Auto Attenuator, 1/16 FDS Diffracted beam optic: Parallel plate collimator (PPC) with silt (0.27) Soller slit (0.04 rad), Xe counter

(66) After the sample stage was adjusted so that a 2 theta (2) value was 0, the half-cut of the sample was confirmed. Then, the incident angle and the reflection angle were set to satisfy the specular condition, and Z.Math.Omega.Math.Z align. Thereby, the sample was prepared to measure X-ray reflectivity. The measurement was performed at 28 between 0.2 and 3.2 with an interval of 0.004.

(67) Thus, the X-ray reflectivity pattern was measured.

(68) The Fourier transform analysis for the result of X-ray reflectivity measurement using CuK-alpha rays was performed by using PANalytical's X'Pert Reflectivity program. In the Fourier transform, the input value was entered as 0.1 for start angle, 1.2 for the end angle, and 0.163 for the critical angle.

(69) TABLE-US-00002 TABLE 2 Average reflec- Scratch Anti- tivity resistance fouling Phase [P1] P2] (%) (g) property separation (nm) (nm) xample 1 0.63 500 40 94 Example 2 0.62 500 48 103 Example 3 0.67 500 43 94 Example 4 0.64 500 41 96.5 Example 5 0.65 500 40.5 91 Example 6 0.67 500 43 90.5 Comparative 0.78 150 X X 43 112 Example 1 Comparative 0.8 200 X 37 80 Example 2 Comparative 0.67 50 X X 38.5 112 Example 3

(70) [P1] and [P2] are the thickness at which the extremal point of the Fourier transform magnitude on the Y-axis appears in a graph showing the result of Fourier transform analysis for the result of X-ray reflectance measurement result using CuK-alpha rays.

(71) TABLE-US-00003 TABLE 3 Reflective Exam- Exam- Exam- Exam- Exam- Exam- index ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 First region 1.502 1.505 1.498 1.491 1.511 1.505 Second region 1.35 1.349 1.321 1.346 1.211 1.375

(72) As confirmed in FIGS. 10 to 15, in a graph showing the result of Fourier transform analysis for the result of X-ray reflectivity measurement using CuK-alpha rays, the antireflection films of Examples 1 to 6 exhibited one extremum at a thickness of 35 nm to 55 nm and exhibited one extremum at a thickness of 85 nm to 105 nm. As shown in Table 2, it was confirmed that the antireflection films of the examples could exhibit low reflectivity of 0.70% or less in the visible light region, and also the high scratch resistance and antifouling properties could be simultaneously realized.

(73) Further, as shown in FIGS. 1 to 6, it was confirmed that, in the low refractive index layer of the antireflection film of Examples 1 to 6, the hollow inorganic nanoparticles and the solid inorganic nanoparticles were phase-separated, and the solid inorganic nanoparticles were mostly present and gathered toward the interface between the hard coating layer and the low refraction layer of the antireflection film, and that the hollow inorganic nanoparticles were mostly present on the side far from the hard coating layer.

(74) Further, as shown in Table 3, it was confirmed that, in the low reflective index layer of the examples, the first region and the second region where the hollow inorganic nanoparticles and the solid inorganic nanoparticles were phase-separated exhibited a reflective index of 1.420 or more and that the second region where the hollow inorganic nanoparticles were mainly distributed exhibited a reflective index of 1.400 or less.

(75) On the other hand, as shown in FIGS. 7 to 9, it was confirmed that, in the low refraction layer of the antireflection film of Comparative Examples 1 to 3, the hollow inorganic nanoparticles and the solid inorganic nanoparticles were mixed without being phase-separated.

(76) In addition, as shown in Table 2 and FIGS. 16 to 18, it was confirmed that the low refractive index layers of the antireflection films of Comparative Examples 1 to 3 did not exhibit an extremum in two thickness ranges of 35 nm to 55 nm and 85 nm to 105 nm in a graph showing the result of Fourier transform analysis for the result of X-ray reflectivity measurement using CuK-alpha rays, and that they had low scratch resistance and antifouling properties while exhibiting relatively high reflectivity.