Anti-reflective film, polarizing plate, and display apparatus

Abstract

Provided are an anti-reflective film including a low-refractive layer having mechanical properties such as high abrasion resistance and scratch resistance, etc., and excellent optical properties, and a hard coating layer, a polarizing plate including the same, and a display device including the same.

Claims

1. An anti-reflective film comprising: a hard coating layer; and a low-refractive layer including an organic polymer resin and two or more kinds of hollow inorganic particles dispersed in the organic polymer resin and having different particle sizes, wherein the two or more kinds of hollow inorganic particles having different particle sizes include a first hollow inorganic particles having a particle size of 35 nm to 61 nm and a second hollow inorganic particles having a particle size of 64 nm to 100 nm, wherein the organic polymer resin included in the low-refractive layer includes a cross-linked (co)polymer between a (co)polymer of a photopolymerizable compound and a fluorine-containing compound including a photoreactive functional group, wherein the (co)polymer of the photopolymerizable compound includes a copolymer of multifunctional (meth)acrylate-based monomers including a di- to tetra-functional (meth)acrylate-based monomer and a penta- to hexa-functional (meth)acrylate-based monomer, wherein a weight ratio of the di- to tetra-functional (meth)acrylate-based monomer and the penta- to hexa-functional (meth)acrylate-based monomer is 9:1 to 6:4, and wherein the anti-reflective film exhibits one or more peaks at a scattering vector (q.sub.max) of 0.128 nm.sup.−1 to 0.209 nm.sup.−1 in a graph showing a log value of a scattering intensity to a scattering vector defined in small-angle X-ray scattering.

2. The anti-reflective film of claim 1, wherein the small-angle X-ray scattering is measured by irradiating X-rays of a wavelength of 0.63 Å 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.

3. The anti-reflective film of claim 1, wherein the scattering vector is defined by 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.

4. The anti-reflective film of claim 1, wherein the first hollow inorganic particles and the second hollow inorganic particles have a particle size ratio of 1:1.05 to 2.85.

5. The anti-reflective film of claim 1, wherein a weight ratio of the first hollow inorganic particles and the second hollow inorganic particles is 7:3 to 3:7.

6. The anti-reflective film of claim 1, wherein the low-refractive layer includes 30 parts by weight to 500 parts by weight of the two or more kinds of the hollow inorganic particles having different particle sizes, based on 100 parts by weight of the (co)polymer of the photopolymerizable compound.

7. The anti-reflective film of claim 1, wherein the organic polymer resin includes 1 to 300 parts by weight of the fluorine-containing compound including the photoreactive functional group, based on 100 parts by weight of the (co)polymer of the photopolymerizable compound.

8. The anti-reflective film of claim 1, further comprising a light transmissive substrate having a thickness-direction retardation (Rth) of 3000 nm or more, as measured at a wavelength of 400 nm to 800 nm.

9. A polarizing plate comprising the anti-reflective film of claim 1 and a polarizing film.

10. A display device comprising the anti-reflective film of claim 1.

11. 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.

12. The anti-reflective film of claim 1, wherein the hard coating layer includes an organic polymer resin of a photocurable resin and an antistatic agent dispersed in the organic polymer resin.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

(1) The present invention will be described in more detail with reference to the following examples. However, the following examples are only to exemplify the present invention, and contents of the present invention are not limited by the following examples.

Preparation Examples 1 to 3: Preparation of Hard Coating Layer

Preparation Example 1

(2) 30 g of pentaerythritol triacrylate, 2.5 g of a high molecular weight copolymer (BEAMSET 371, Arakawa Co. Ltd., epoxy acrylate, weight average molecular weight: 40,000), 20 g of methylethylketone, and 0.5 g of a leveling agent (Tego wet 270) were uniformly mixed, and then 2 g of acryl-styrene copolymer fine particles (volume average particle size: 2 μm, Manufacturing Company: Sekisui Plastic) with a refractive index of 1.525 was added to prepare a hard coating composition.

(3) The hard coating composition thus obtained was coated on a triacetyl cellulose film using a #10 Mayer bar and dried at 90° C. for 1 minute. The dried coating was irradiated with UV light of 150 mJ/cm.sup.2 to prepare a hard coating layer with a thickness of 4 μm.

Preparation Example 2

(4) The hard coating composition of Preparation Example 1 was coated on a PET film having a thickness of 80 μm and retardation of 10,000 nm using a #10 Mayer bar and dried at 60° C. for 1 minute. The dried coating was irradiated with UV light of 150 mJ/cm.sup.2 to prepare a hard coating layer with a thickness of 4 μm.

Preparation Example 3

(5) A salt-type antistatic hard coating solution of KYOEISHA Chemical Co., Ltd. (solid content: 50% by weight, product name: LJD-1000) was coated on a triacetyl cellulose film using a #10 Mayer bar, dried at 90° C. for 1 minute, and irradiated with UV light of 150 mJ/cm.sup.2, thereby preparing a hard coating layer having a thickness of about 5 μm.

Examples 1 to 6: Preparation of Anti-Reflective Film

Example 1

(6) Based on 100 parts by weight of trimethylolpropane triacrylate (TMPTA), 40 parts by weight of first hollow silica nanoparticles (particle size: 53.1 nm, as measured by a dynamic light scattering method), 78 parts by weight of second hollow silica nanoparticles (particle size: 73.5 nm, as measured by a dynamic light scattering method), 15 parts by weight of a fluorine-containing compound (RS-90, DIC), and 25 parts by weight of an initiator (Irgacure 127, Ciba) were diluted in a MIBK (methyl isobutyl ketone) solvent such that a solid content was 3.0% by weight, thereby preparing a photocurable coating composition.

(7) The photocurable coating composition was coated on the hard coating film of Preparation Example 1 using a #4 Mayer bar so as to have a thickness of about 110 nm to 120 nm, and dried and cured at a temperature of 60° C. for 1 minute, thereby manufacturing an anti-reflective film. At the time of curing, the dried coating resultant was irradiated with UV light of 252 mJ/cm.sup.2 under nitrogen purging.

Example 2

(8) Based on 100 parts by weight of a mixed binder of pentaerythritol triacrylate (PETA) and dipentaerythritol hexaacrylate (DPHA) (mixing ratio of PETA:DPHA=7:3), 60 parts by weight of first hollow silica nanoparticles (particle size: 50.2 nm, as measured by a dynamic light scattering method), 80 parts by weight of second hollow silica nanoparticles (particle size: 71.7 nm, as measured by a dynamic light scattering method), 32 parts by weight of a fluorine-containing compound (RS-907, DIC), and 29.3 parts by weight of an initiator (Irgacure 127, Ciba) were diluted in a MIBK (methyl isobutyl ketone) solvent such that a solid content was 3.3% by weight, thereby preparing a photocurable coating composition.

(9) The photocurable coating composition was coated on the hard coating film of Preparation Example 1 using a #4 Mayer bar so as to have a thickness of about 110 nm to 120 nm, and dried and cured at a temperature of 60° C. for 1 minute, thereby manufacturing an anti-reflective film. At the time of curing, the dried coating resultant was irradiated with UV light of 252 mJ/cm.sup.2 under nitrogen purging.

Example 3

(10) Based on 100 parts by weight of a mixed binder of pentaerythritol triacrylate (PETA) and dipentaerythritol hexaacrylate (DPHA) (a mixing ratio of PETA:DPHA=6:4), 110 parts by weight of first hollow silica nanoparticles (particle size: 43.3 nm, as measured by a dynamic light scattering method), 62 parts by weight of second hollow silica nanoparticles (particle size: 68.7 nm, as measured by a dynamic light scattering method), 147 parts by weight of solid silica nanoparticles (particle size: about 18 nm), 17 parts by weight of a fluorine-containing compound (RS-907, DIC), and 14.6 parts by weight of an initiator (Irgacure 127, Ciba) were diluted in a MIBK (methyl isobutyl ketone) solvent such that a solid content was 2.8% by weight, thereby preparing a photocurable coating composition.

(11) The photocurable coating composition was coated on the hard coating film of Preparation Example 1 using a #4 Mayer bar so as to have a thickness of about 110 nm to 120 nm, and dried and cured at a temperature of 60° C. for 1 minute, thereby manufacturing an anti-reflective film. At the time of curing, the dried coating resultant was irradiated with UV light of 252 mJ/cm.sup.2 under nitrogen purging.

Example 4

(12) Based on 100 parts by weight of TMPTA, 81.2 parts by weight of first hollow silica nanoparticles (particle size: 47.7 nm, as measured by a dynamic light scattering method), 60.8 parts by weight of second hollow silica nanoparticles (particle size: 78.9 nm, as measured by a dynamic light scattering method), 115 parts by weight of solid silica nanoparticles (particle size: about 13 nm), 10.1 parts by weight of a fluorine-based compound (RS-907, DIC), and 8.4 parts by weight of an initiator (Irgacure 127, Ciba) were diluted in a MIBK (methyl isobutyl ketone) solvent such that a solid content was 3.2% by weight, thereby preparing a photocurable coating composition.

(13) The photocurable coating composition was coated on the hard coating film of Preparation Example 2 using a #4 Mayer bar so as to have a thickness of about 110 nm to 120 nm, and dried and cured at a temperature of 60° C. for 1 minute. At the time of curing, the dried coating resultant was irradiated with UV light of 252 mJ/cm.sup.2 under nitrogen purging.

Example 5

(14) Based on 100 parts by weight of PETA, 134.2 parts by weight of first hollow silica nanoparticles (particle size: 45.5 nm, as measured by a dynamic light scattering method), 234.8 parts by weight of second hollow silica nanoparticles (particle size: 82.1 nm, as measured by a dynamic light scattering method), 67 parts by weight of solid silica nanoparticles (particle size: about 12 nm), 115 parts by weight of a fluorine-based compound (RS-923, DIC), and 31 parts by weight of an initiator (Irgacure 907, Ciba) were diluted in a MIBK (methyl isobutyl ketone) solvent such that a solid content was 2.9% by weight, thereby preparing a photocurable coating composition.

(15) The photocurable coating composition was coated on the hard coating film of Preparation Example 3 using a #4 Mayer bar so as to have a thickness of about 110 nm to 120 nm, and dried and cured at a temperature of 60° C. for 1 minute, thereby manufacturing an anti-reflective film. At the time of curing, the dried coating resultant was irradiated with UV light of 252 mJ/cm.sup.2 under nitrogen purging.

Example 6

(16) Based on 100 parts by weight of a mixed binder of pentaerythritol triacrylate (PETA) and dipentaerythritol hexaacrylate (DPHA) (a mixing ratio of PETA:DPHA=5:5), 111 parts by weight of first hollow silica nanoparticles (particle size: 53.1 nm, as measured by a dynamic light scattering method), 91 parts by weight of second hollow silica nanoparticles (particle size: 77.2 nm, as measured by a dynamic light scattering method), 55 parts by weight of solid silica nanoparticles (particle size: about 18 nm), 85 parts by weight of a fluorine-based compound (RS-907, DIC), and 17.1 parts by weight of an initiator (Irgacure 127, Ciba) were diluted in a MIBK (methyl isobutyl ketone) solvent such that a solid content was 3.0% by weight, thereby preparing a photocurable coating composition.

(17) The photocurable coating composition was coated on the hard coating film of Preparation Example 3 using a #4 Mayer bar so as to have a thickness of about 110 nm to 120 nm, and dried and cured at a temperature of 60° C. for 1 minute, thereby manufacturing an anti-reflective film. At the time of curing, the dried coating resultant was irradiated with UV light of 252 mJ/cm.sup.2 under nitrogen purging.

Comparative Examples 1 to 6: Preparation of Anti-Reflective Film

Comparative Example 1

(18) An anti-reflective film was manufactured in the same manner as in Example 1, except that only 118 parts by weight of hollow silica nanoparticles (particle size: 44.1 nm, as measured by a dynamic light scattering method) was used without using a mixture of first hollow silica nanoparticles (particle size: 53.1 nm, as measured by a dynamic light scattering method) and second hollow silica nanoparticles (particle size: 73.5 nm, as measured by a dynamic light scattering method).

Comparative Example 2

(19) An anti-reflective film was manufactured in the same manner as in Example 2, except that only 140 parts by weight of hollow silica nanoparticles (particle size: 47.4 nm, as measured by a dynamic light scattering method) was used without using a mixture of first hollow silica nanoparticles (particle size: 50.2 nm, as measured by a dynamic light scattering method) and second hollow silica nanoparticles (particle size: 71.7 nm, as measured by a dynamic light scattering method).

Comparative Example 3

(20) An anti-reflective film was manufactured in the same manner as in Example 3, except that only 172 parts by weight of hollow silica nanoparticles (particle size: 49.1 nm, as measured by a dynamic light scattering method) was used without using a mixture of first hollow silica nanoparticles (particle size: 43.3 nm, as measured by a dynamic light scattering method) and second hollow silica nanoparticles (particle size: 68.7 nm, as measured by a dynamic light scattering method).

Comparative Example 4

(21) An anti-reflective film was manufactured in the same manner as in Example 4, except that only 172 parts by weight of hollow silica nanoparticles (particle size: 100.1 nm, as measured by a dynamic light scattering method) was used without using a mixture of first hollow silica nanoparticles (particle size: 47.7 nm, as measured by a dynamic light scattering method) and second hollow silica nanoparticles (particle size: 78.9 nm, as measured by a dynamic light scattering method).

Comparative Example 5

(22) An anti-reflective film was manufactured in the same manner as in Example 5, except that 295.2 parts by weight of first hollow silica nanoparticles (particle size: 44.1 nm, as measured by a dynamic light scattering method) and 73.8 parts by weight of second hollow silica nanoparticles (particle size: 93.5 nm, as measured by a dynamic light scattering method) were used instead of 134.2 parts by weight of first hollow silica nanoparticles (particle size: 45.5 nm, as measured by a dynamic light scattering method) and second hollow silica nanoparticles (particle size: 82.1 nm, as measured by a dynamic light scattering method).

Comparative Example 6

(23) An anti-reflective film was manufactured in the same manner as in Example 6, except that 40.4 parts by weight of first hollow silica nanoparticles (particle size: 40.8 nm, as measured by a dynamic light scattering method) and 161.6 parts by weight of second hollow silica nanoparticles (particle size: 79.7 nm, as measured by a dynamic light scattering method) were used instead of 111 parts by weight of first hollow silica nanoparticles (particle size: 53.1 nm, as measured by a dynamic light scattering method) and 91 parts by weight of second hollow silica nanoparticles (particle size: 77.2 nm, as measured by a dynamic light scattering method).

(24) Evaluation

(25) 1. Measurement of Particle Size Range of Hollow Inorganic Particles

(26) The particle size ranges of the hollow inorganic particles included in the low-refractive layers of the anti-reflective films obtained in the examples and comparative examples were measured using a transmission electron microscope (TEM). In detail, any part of each anti-reflective film was selected, and photographed with a transmission electron microscope at 25,000× magnification. The particle sizes of the hollow particles identified in the photograph were measured and divided into two groups, and the results are described in the following Table 1.

(27) TABLE-US-00001 TABLE 1 Particle size range Particle size range of hollow of hollow inorganic particles inorganic particles (Group 1) (Group 2) Example 1 46.3 nm~60.8 nm   66 nm~81.3 nm Example 2 41.1 nm~60.2 nm 64.5 nm~78.1 nm Example 3 37.3 nm~50.1 nm 64.5 nm~73.5 nm Example 4 39.1 nm~57.3 nm 70.3 nm~95.2 nm Example 5 35.3 nm~55.8 nm 66.3 nm~98 nm   Example 6 47.3 nm~60.5 nm 67.5 nm~83.1 nm Comparative 36.2 nm~51.9 nm — Example 1 Comparative 30.6 nm~62.1 nm — Example 2 Comparative 31.8 nm~65.3 nm — Example 3 Comparative —  83.1 nm~120.3 nm Example 4 Comparative 36.5 nm~51.8 nm  78.7 nm~108.4 nm Example 5 Comparative 32.8 nm~48.1 nm 70.1 nm~89.5 nm Example 6

(28) Referring to the particle size ranges of the hollow inorganic particles of the examples in Table 1, it was confirmed that Group 1 and Group 2 meet the particle size of 35 nm to 61 nm and 64 nm to 100 nm, respectively, while the comparative examples include hollow inorganic particles having one particle size range, or do not meet the particle size range.

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

(30) To a specimen of 1 cm*1 cm (width*length) obtained from each of the anti-reflective films of the examples and comparative examples, X-rays of a wavelength of 1.54 Å were irradiated at a distance of 4 m to measure the scattering vector and scattering intensity.

(31) In detail, scattering intensity according to the scattering vector (q) was measured by transmitting X-rays through the specimen at a 4C beam line of a Pohang accelerator. In more detail, 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 a 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]

(32) 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.

(33) Based on the above measurement results, a scattering vector (q.sub.max) 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, and the results are shown in the following Table 2.

(34) 3. Measurement of Reflectance Before and after Rubbing Test

(35) The surface of the hard coating layer of each of the anti-reflective films obtained in the examples and comparative examples, on which the low-refractive layer was not formed, was subjected to a darkening process to prevent light transmission. Before and after a rubbing test, the average reflectance of the low-refractive layer of each anti-reflective film was measured. At this time, the rubbing test to rub the surface of the low-refractive layer was performed by a method of applying a load of 500 g to a steel wool with #0000 grade, and reciprocating ten times at a speed of 33 rpm.

(36) In detail, before the rubbing test, a darkening treatment of the surface, on which no hard coating layer and no low-refractive layer were formed, was performed to prevent light transmission, and average reflectance was measured in a wavelength range of 380 nm to 780 nm using a reflectance mode of Solidspec 3700 (UV-Vis spectrophotometer, SHIMADZU). The results are shown in “R.sub.0” of the following Table 1. After the rubbing test, average reflectance was measured for the low-refractive layer in the same manner as the method of measuring R.sub.0, and the results are shown in “R.sub.1” of the following Table 2. Further, a difference between R.sub.0 and R.sub.1 was calculated, and variation in the reflectance before and after the rubbing test is shown in “ΔR” of the following Table 2.

(37) 4. Measurement of Color Coordinate Value (b*)

(38) The surface of the hard coating layer of each of the anti-reflective films obtained in the examples and comparative examples, on which the low-refractive layer was not formed, was subjected to a darkening process to prevent light transmission. Before and after a rubbing test, reflectance was measured using a reflectance mode of Solidspec 3700 (UV-Vis spectrophotometer, SHIMADZU), and a color coordinate value (b*) of the low-refractive layer was measured using a UV-2401PC Color Analysis program. At this time, the rubbing test to rub the surface of the low-refractive layer was performed by a method of applying a load of 500 g to a steel wool with #0000 grade, and reciprocating ten times at a speed of 33 rpm.

(39) In detail, before the rubbing test, the color coordinate value of the low-refractive layer was measured and the results are in “b*.sub.0” of the following Table 2. After the rubbing test, the color coordinate value was measured for the low-refractive layer in the same manner as the method of measuring b*.sub.0, and the results are shown in “b*.sub.1” of the following Table 2. Further, a difference between b*.sub.0 and b*.sub.1 was calculated, and variation in the color coordinate values before and after the rubbing test is shown in “Δb*” of the following Table 2.

(40) 5. Measurement of Scratch Resistance

(41) While a steel wool with #0000 grade was loaded and allowed to reciprocate 10 times at 27 rpm, the low-refractive layer of each of the anti-reflective films obtained in Examples and Comparative Examples was rubbed. The maximum load under which one or less scratch of 1 cm or less was observed with the unaided eye, was measured. The results are shown in the following Table 2.

(42) 6. Measurement of Anti-Fouling Property

(43) The anti-fouling property was measured by drawing a straight line having a length of 5 cm on the low-refractive layer of each of the anti-reflective films obtained in the examples and comparative examples using a black felt pen and confirming the number of scrubbing actions required for erasing the straight line at the time of scrubbing the anti-reflective film with a wiper. The results are shown in the following Table 2.

(44) <Measurement Standard>

(45) O: The number of rubbing actions required for erasing the straight line was 10 or less.

(46) Δ: The number of rubbing actions required for erasing the straight line was 11 to 20.

(47) X: The number of rubbing actions required for erasing the straight line was more than 20.

(48) TABLE-US-00002 TABLE 2 q.sub.max R.sub.0 R.sub.1 ΔR Scratch Anti-fouling (nm.sup.−1) (%) (%) (% p) b.sub.0.sup.* b.sub.1.sup.* Δb* resistance (g) property Example 1 0.201 1.58 1.6 0.02 −3.28 −3.21 0.07 500 ◯ Example 2 0.199 1.48 1.50 0.02 −3.87 −3.85 0.02 500 ◯ Example 3 0.174 1.37 1.40 0.03 −4.01 −3.81 0.2 500 ◯ Example 4 0.155 1.13 1.20 0.07 −3.92 −3.62 0.3 500 ◯ Example 5 0.148 0.67 0.71 0.04 −2.98 −2.7 0.28 500 ◯ Example 6 0.131 0.25 0.29 0.04 −4.87 −4.46 0.41 300 ◯ Comparative 0.214 1.55 1.81 0.26 −3.33 −2.82 0.51 500 ◯ Example 1 Comparative 0.225 1.52 1.8 0.28 −2.11 −1.49 0.62 500 ◯ Example 2 Comparative 0.231 1.4 1.72 0.32 −1.98 −1.28 0.7 500 ◯ Example 3 Comparative 0.071 1.21 1.51 0.30 −3.76 −3.08 0.68 500 ◯ Example 4 Comparative 0.092 0.79 1.01 0.22 −4.71 −3.73 0.98 300 ◯ Example 5 Comparative 0.125 0.3 0.59 0.29 −4.42 −3.32 1.1 200 X Example 6

(49) As shown in Table 2, the results of measuring the ‘scattering intensity according to scattering vector in small-angle X-ray scattering’ for the anti-reflective films of Examples 1 to 6 showed that a first peak appeared at a scattering vector (q.sub.max) of 0.128 nm.sup.−1 to 0.209 nm.sup.−1. In contrast, the results of measuring the ‘scattering intensity according to scattering vector in small-angle X-ray scattering’ for the anti-reflective films of Comparative Examples 1 to 6 showed that a first peak appeared at a scattering vector outside the range of 0.128 nm.sup.−1 to 0.209 nm.sup.−1.

(50) Further, the anti-reflective films of Examples 1 to 6 which meet the value range of the scattering vector showed remarkably low variation in the reflectance (ΔR) and the color coordinate value (Δb*) before and after the rubbing test, as compared with those of Comparative Examples 1 to 6 which do not meet the above value range. Accordingly, it may be expected that the anti-reflective films of Examples 1 to 6 may effectively inhibit the increase of reflectance at a portion that is damaged or deformed due to external rubbing or friction.