JP6167488B2 - Anti-reflection coating - Google Patents

Description

  The present invention relates to an antireflection film.

In a liquid crystal display device or the like, if the surface of the display screen reflects light, the displayed image or the like becomes difficult to see. As a technique for eliminating the reflection of the display screen, a technique of suppressing reflection by laminating a low refractive index layer on the display screen is known. A technique related to the antireflection film is described in Patent Document 1, for example.
Further, since the antireflection film is formed on the uppermost layer of the display screen, the visibility of the display image is impaired due to scratches. For this reason, some antireflection films require hardness on the surface.

  The antireflection film whose surface is required to be hard is formed, for example, by laminating a hydrolyzate of metal alkoxide (in this case, metal is Si), a so-called sol-gel layer as a low refractive index layer on a hard coat layer. Is known (for example, Patent Document 2). However, the adhesion between the sol-gel layer and the hard coat layer is insufficient to function as an antireflection film, and it is necessary to enhance the adhesion with the sol-gel layer by treating the hard coat layer with an alkali.

JP 2003-292831 A JP 2008-007786 A

However, the above-described alkali treatment requires heating a relatively high concentration alkaline solution (such as about 2N NaOH) and immersing the hard coat layer in the alkaline solution for a certain period of time. In order to perform such processing, dedicated equipment is required, and the cost of the equipment may lead to an increase in the cost of the antireflection film.
This invention is made | formed in view of such a point, and it aims at providing the anti-reflective film which a sol-gel layer and a hard-coat layer have sufficient adhesiveness, without performing an alkali treatment.

The invention of claim 1 of the present invention comprises a transparent substrate (103), a hard coat layer (102) formed on one surface (103a) side of the transparent substrate (103), and a surface of the hard coat layer. Among them, a low refractive index layer (101) of silicon oxide, which is a hydrolytic condensate of an organosilicon compound, formed on the surface (102a) opposite to the transparent substrate (103), and the hard coat layer, An antireflective film (1) having a silicon oxide anchor layer (111) of 1 nm or more and 10 nm or less between the low refractive index layer.
A second aspect of the present invention is the antireflection film according to the first aspect, wherein the anchor layer is a layer formed by sputtering.
A third aspect of the present invention is the antireflection film according to the first or second aspect, wherein the anchor layer has a thickness of 3 nm to 7 nm.
According to a fourth aspect of the present invention, in any one of the first to third aspects, the hard coat layer is an antireflection film containing an acrylic active energy ray-curable resin.

  The present invention can provide an antireflection film in which the sol-gel layer and the hard coat layer have sufficient adhesion without performing an alkali treatment.

It is a figure for demonstrating the antireflection film of one Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described.
FIG. 1 is a diagram for explaining the antireflection film of the present embodiment. The antireflection film of the present embodiment includes a transparent base material 103, a hard coat layer 102 formed on the surface 103a side of the transparent base material 103, and a surface of the hard coat layer 102 opposite to the transparent base material 103. This is an antireflection film 1 having a low refractive index layer 101 formed on the surface 102a, and an anchor layer 111 formed by sputtering between the hard coat layer 102 and the low refractive index layer 101.
In the present embodiment, the thickness of the anchor layer 111 is 1 nm or more and 10 nm or less, and more preferably 3 nm or more and 7 nm or less.

Hereinafter, each layer shown in FIG. 1 will be described in detail.
<Transparent substrate film>
The material of the transparent base film 103 is not particularly limited, but a general material used for an antireflection film can be used, and for example, cellulose acylate, cycloolefin polymer, acrylate polymer, or polyester is mainly used. Those are preferred. Here, “mainly” means a component having the highest content ratio among the constituent components of the base material.

  Specific examples of cellulose acylate include cellulose triacetate, cellulose diacetate, and cellulose acetate butyrate. Examples of the cycloolefin polymer include a norbornene polymer, a monocyclic olefin polymer, a cyclic conjugated diene polymer, a vinyl alicyclic hydrocarbon polymer resin, and more specifically, ZEONEX and ZEONOR (norbornene resin) manufactured by Nippon Zeon Co., Ltd., Sumitrite FS-1700 manufactured by Sumitomo Bakelite Co., Ltd., Arton (modified norbornene resin) manufactured by JSR Corporation, and Appel (cyclic olefin) manufactured by Mitsui Chemicals Copolymer), Topas (cyclic olefin copolymer) manufactured by Ticona, Optretz OZ-1000 series (alicyclic acrylic resin) manufactured by Hitachi Chemical Co., Ltd., and the like. Specific examples of the acrylate polymer include methyl poly (meth) acrylate, poly (meth) ethyl acrylate, methyl (meth) acrylate-butyl (meth) acrylate, and the like. Specific examples of the polyester include polyethylene terephthalate and polyethylene naphthalate.

In the present invention, the thickness of the transparent substrate film 103 is 20 μm or more and 300 μm or less, preferably 30 μm or more and 200 μm or less. When forming the hard coat layer 102 on the transparent substrate film, in order to improve adhesion, in addition to physical treatment such as corona discharge treatment and oxidation treatment, application of a paint called an anchor agent or primer is applied. May be performed in advance.
<Hard coat layer>
The hard coat layer 102 is composed of a film A containing an acrylic active energy ray-curable resin. The acrylic active energy ray-curable resin is not particularly limited, and conventionally known ones can be used. For example, what is necessary is just to form using the polymer which has a polyfunctional monomer which contains two or more (meth) acryloyloxy groups in 1 molecule as a main component.

  Polyfunctional monomers include 1,4-butanediol (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol (meth) acrylate, ethylene glycol di (meth) acrylate, and triethylene glycol di (Meth) acrylate, tripropylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, 3-methylpentadiol di (meth) acrylate, diethylene glycol bis β- (meth) acryloyloxypropionate, trimethylolethanetri (Meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tri (2-hydro Cyethyl) isocyanate di (meth) acrylate, pentaerythritol tetra (meth) acrylate, 2,3-bis (meth) acryloyloxyethyloxymethyl [2.2.1] heptane, poly 1,2-butadiene di (meth) acrylate 1,2-bis (meth) acryloyloxymethylhexane, nonaethylene glycol di (meth) acrylate, tetradecane ethylene glycol di (meth) acrylate, 10-decanediol (meth) acrylate, 3,8-bis (meth) acryloyl Oxymethyltricyclo [5.2.10] decane, hydrogenated bisphenol A di (meth) acrylate, 2,2-bis (4- (meth) acryloyloxydiethoxyphenyl) propane, 1,4-bis ((meta ) Acryloyloxymethyl) Examples include cyclohexane, hydroxypivalate ester neopentyl glycol di (meth) acrylate, bisphenol A diglycidyl ether di (meth) acrylate, and ethoxylated bisphenol A di (meth) acrylate. Only one type of polyfunctional monomer may be used, or two or more types may be used in combination. Further, if necessary, it can be copolymerized in combination with a monofunctional monomer.

  When forming a hard coat layer, an organic solvent is added to the polyfunctional monomer, and a composition in which a polymerization initiator or a leveling agent is added if necessary is prepared on a transparent substrate film by a conventionally known wet coating method. Apply. At that time, in order to prevent interference fringes generated at the interface between the hard coat layer and the transparent substrate film, it is desirable to mix the organic solvent with a material that penetrates or dissolves the transparent substrate film.

  The film thickness of the hard coat layer 102 is preferably 2 μm to 20 μm. 5 to 10 μm is particularly preferred. If it is too thin, the hardness of the hard coat layer will be insufficient, and the penetration layer will not be sufficiently formed, preventing interference fringes. If it is too thick, cracks are likely to occur during handling. A preferable refractive index is 1.6 or more and 2.0 or less. Further, the refractive index may be adjusted by mixing and dispersing inorganic fine particles or organic fine particles having an average particle diameter of 0.01 μm to 0.1 μm in the hard coat layer 102, and the surface shape of the hard coat layer 102 may be uneven. May be.

<Low refractive index layer>
The low refractive index layer 101 is formed directly on the hard coat layer without any surface treatment, and is composed of a film mainly including a silicon oxide film that is a hydrolysis condensate of an organosilicon compound. This is a thermosetting silicon oxide film obtained by a so-called sol-gel method of silicon oxide. Thereby, sufficient hardness is obtained. The silicon oxide in the present invention means SiOx (X is 1.8 to 2.0).

  The organosilicon compound is a so-called polyfunctional alkoxysilane, and it is preferable to use a tetrafunctional alkoxysilane from the viewpoint of film hardness.

Si (OR) ₄ (R is an alkyl group), which is a tetrafunctional alkoxysilane, includes Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OC ₃ H ₇ ) ₄ , Si [OCH (CH ₃ ) ₂ ] ₄ , Si (OC ₄ H ₉ ) ₄ may be mentioned, and these may be used alone or in combination of two or more.

In addition, trifunctional or lower functional alkoxysilanes or alkoxysilanes having a fluorine-substituted alkyl group, such as CH ₃ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ , CF ₃ CF ₂ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ , CF ₃ (CF ₂ ) ₂ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ , CF ₃ (CF ₂ ) ₃ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ , CF ₃ (CF ₂ ) ₄ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ , CF ₃ (CF ₂ ) ₅ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ , CF ₃ (CF ₂ ) ₆ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ , CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ , CF ₃ (CF ₂ ) ₈ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ , CF ₃ (CF ₂ ) ₉ (CH ₂ ) ₂ Si (OCH ₃ ) _3, C _{3 (CH 2) 2 Si (} OC 2 H 5) 3, CF 3 CF 2 (CH 2) 2 Si (OC 2 H 5) 3, CF 3 (CF 2) 2 (CH 2) 2 Si (OC 2 H ₅ ) ₃ , CF ₃ (CF ₂ ) ₃ (CH ₂ ) ₂ Si (OC ₂ H ₅ ) ₃ , CF ₃ (CF ₂ ) ₄ (CH ₂ ) ₂ Si (OC ₂ H ₅ ) ₃ , CF 3 (CF ₂ ) ₅ (CH ₂ ) ₂ Si (OC ₂ H ₅ ) ₃ , CF ₃ (CF ₂ ) ₆ (CH ₂ ) ₂ Si (OC ₂ H ₅ ) ₃ , CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₂ Si (OC ₂ H ₅ ) ₃ , CF ₃ (CF ₂ ) ₈ (CH ₂ ) ₂ Si (OC ₂ H ₅ ) ₃ , CF ₃ (CF ₂ ) ₉ (CH ₂ ) ₂ Si (OC ₂ H ₅ ) _3, etc. May be used in combination.

  What is necessary is just to apply | coat the coating solution which has said organosilicon compound as a main component, diluting with a solvent. Diluting solvents used include alcohols such as methanol, ethanol, isopropanol, butanol and 2-methoxyethanol, ketones such as acetone, methyl ethyl ketone and methyl isobutyl, esters such as methyl acetate, ethyl acetate and butyl acetate, diisopropyl ether Ethers such as ethylene glycol, propylene glycol and hexylene glycol, glycol ethers such as ethyl cellosolve, butyl cellosolve and ethyl carbitol, aliphatic hydrocarbons such as hexane, heptane and octane, halogenated hydrocarbons , Aromatic hydrocarbons such as benzene, toluene and xylene, N-methylpyrrolidone, dimethylformamide and the like.

  The coating solution is applied onto the hard coat layer by a conventionally known wet coating method (dip coating method, spin coating method, flow coating method, spray coating method, roll coating method, gravure coating method, etc.). Thereafter, the low refractive index layer 101 is formed through a heating process.

  The film thickness of the low refractive index layer 101 is preferably 50 nm to 150 nm. A preferable refractive index is 1.4 or more and 1.5 or less.

<Anchor layer>
As the anchor layer 111, a silicon oxide (SiOx) thin film of 1 nm to 10 nm, preferably formed by sputtering, is used. From the viewpoints of heat damage to the transparent base material 103, uneven thickness of the anchor layer, adhesion, etc., reactive sputtering is preferably used. The sputtering method is known to have good film thickness stability although the film formation rate is lower than the deposition method such as EB (ion beam) method and IP (ion plating) method. And although the reason is unknown for the thin film formed by sputtering, it is excellent also in adhesion | attachment with not only a low refractive index layer but a hard-coat layer. Thereby, adhesiveness can be improved.

  As described above, the thickness of the anchor layer 111 of this embodiment is 1 nm or more and 10 nm or less, and preferably 3 nm or more and 7 nm or less. In this embodiment, since the anchor layer 111 is thin, the time required for forming the anchor layer 111 can be reduced. Of the sputtering methods, magnetron sputtering is advantageous for increasing the film formation rate.

  The reason why the anchor layer 111 is 10 nm or less is that when the anchor layer 111 exceeds 10 nm, the refractive index of the low refractive index layer 101 is affected and a desired refractive index cannot be obtained. The reason why the anchor layer 111 is set to 1 nm or more is that when the anchor layer 111 is less than 1 nm, a region where a silicon oxide film is not formed is generated, and the anchor layer 111 can no longer function as an anchor layer.

  In addition, preferable reflective hues in the CIE L * a * b * color space are a * = 1 to 10, b * = − 3 to −20, and more preferably, a * = 3 to 7 and b * =. -13 to -17. The film thickness unevenness of the anchor layer and the low refractive index layer is visually recognized as color unevenness when observed obliquely. Although the reflection hue near a * = 0 and b * = 0 is neutral, slight film thickness unevenness is easily recognized as color unevenness, and stable production is difficult. In addition, since reflection colors other than the blue system have a poor image, by setting a * = 1 to 10 and b * = − 3 to −20, even if there is a film thickness unevenness, the color unevenness is not noticeable and a high-class feeling. The reflected blue hue can be obtained.

  Next, examples and comparative examples of the antireflection film of the present embodiment described above will be described.

(Example)
<(1) Sputtering conditions>
The sputtering conditions for the anchor layer 111 of this example are as follows.
・ Magnetron sputtering ・ Target size: 40cm length x 15cm width ・ Distance between target and transparent substrate: 60mm
-Input power: 1.0 kW
・ Film formation pressure 4 × 10 ⁻¹ Pa
・ Line speed: 1m / min
・ Film thickness: 5nm

<(2) Hard coat layer ink>
The hard coat layer ink for forming the hard coat layer 102 had the following composition.
Pentaerythritol triacrylate (PETA): 65 parts by weight Isocyanuric acid-modified diacrylate (M-215) (manufactured by Toagosei Co., Ltd.): 35 parts by weight Irgacure 184 (photopolymerization initiator): 6 parts by weight Silicone (Leveling agent): 0.045 parts by weight Reactive highly refractive fine particles in which an organic component is introduced on the titanium surface (average particle size 55 nm): 6.8 parts by weight Reactive inorganic fine particles in which an organic component is introduced on the silica surface ( Average particle diameter 60 nm): 20 parts by weight Toluene: 64 parts by weight

Reactive highly bent fine particles were prepared by removing surface adsorbed ions and surface treatment (introduction of monofunctional monomer). The titanium fine particles (reactive high refractive fine particles) thus obtained had an average particle size of d50 = 55 nm as a result of measurement using a Nanotrac particle size analyzer manufactured by Nikkiso Co., Ltd. Further, the amount of the organic component covering the surface of the titanium fine particles was 3.12 × 10 ⁻³ g / m ² as a result of measurement by thermogravimetric analysis. Further, the specific gravity of the obtained reactive high refractive fine particles was 1.72.

The reactive inorganic fine particles were prepared by using water-dispersed colloidal silica having a particle diameter of 60 nm instead of the water-dispersed colloidal titanium having an adjusted particle diameter of 50 nm. The reactive inorganic fine particles thus obtained had an average particle size of d50 = 60 nm as a result of measurement by the particle size analyzer. The amount of the organic component covering the surface was 3.55 × 10 ⁻³ g / m ² as a result of measurement by thermogravimetric analysis. Moreover, the specific gravity of the obtained reactive inorganic fine particles was 2.14.

<(3) Sol-gel layer ink>
Tetraethoxysilane / PVA / water / HCl = 26/36/9/14 was used as the ink for the sol-gel layer.

  As the antireflection film, a hard coat layer ink was applied to a TAC having a thickness of 80 μm with a wire bar, dried, and irradiated with UV to obtain a hard coat layer 102 having a thickness of 10 μm. Next, the anchor layer 111 was formed by laminating 5 nm of silicon oxide by sputtering. Furthermore, the sol-gel layer ink was applied with a wire bar and cured in a drying furnace at 120 ° C. for 2 hours to form a 0.1 μm low refractive index layer 101.

  The antireflection film 1 produced by the above procedure has a total light transmittance of 92% and a luminous reflectance of 0.8% as measured with a spectrophotometer (manufactured by JASCO Corporation, V-7100). The reflection hues in the L * a * b * chromaticity system are a * = 6 and b * = − 15. Further, the adhesion between the hard coat layer 102 and the low refractive index layer 101 was evaluated by a cross-cut test (JIS K5400-8.5). As a result, peeling between the hard coat layer 102 and the low refractive index layer 101 was not observed.

(Comparative example)
Comparative Example 1
The antireflection film of Comparative Example 1 was produced in the same manner as the antireflection film of the above-described example except that the anchor layer 111 was not provided. The antireflection film of Comparative Example 1 had a total light transmittance of 92% and a luminous reflectance of 0.8%. The reflected hues were a * = 7 and b * = − 12. Further, when the adhesion between the hard coat layer and the low refractive index layer was evaluated by a cross cut test (JIS K5400-8.5), 80/100 peeling was observed.
Comparative Example 2
The antireflection film of Comparative Example 2 was produced in the same manner as the antireflection film of the above-described example except that the line speed was 10 m / min and the film thickness was 0.5 nm in sputtering. The antireflection film of Comparative Example 2 had a total light transmittance of 92% and a luminous reflectance of 0.8%. The reflected hues were a * = 7 and b * = − 12. Further, when the adhesion between the hard coat layer and the low refractive index layer was evaluated by a cross-cut test (JIS K5400-8.5), 50/100 peeling was observed.
Comparative Example 3
The antireflection film of Comparative Example 3 was produced in the same manner as the above-described antireflection film except that the line speed was 0.25 m / min and the film thickness was 20 nm in sputtering. The total light transmittance of the antireflection film of Comparative Example 2 was 91%, and the luminous reflectance was 2%. The reflected hues were a * = 2 and b * = − 18. Further, when the adhesion between the hard coat layer and the low refractive index layer was evaluated by a cross-cut test (JIS K5400-8.5), no peeling was observed. However, according to Comparative Example 3, since the luminous reflectance was as high as 2%, it was impossible to provide an antireflection film having a sufficiently low reflectance while having high adhesion.

  The antireflection film of the present invention is provided on the surface of a display or the like of an electronic device, and is suitable for preventing reflection of a display screen.

DESCRIPTION OF SYMBOLS 101 Low refractive index layer 102 Hard-coat layer 102a, 103a Surface 103: Transparent base material 111: Anchor layer

Claims (3)

A transparent substrate;
A hard coat layer formed on one side of the transparent substrate;
Of the surface of the hard coat layer, formed on the surface opposite to the transparent substrate, a low refractive index layer of silicon oxide that is a hydrolytic condensate of an organosilicon compound,
A silicon oxide anchor layer of 1 nm or more and 10 nm or less between the hard coat layer and the low refractive index layer;
An antireflection film in which reflection hues in a CIE L ^* a ^* b ^* color space are a ^* = 3 to 7 and b ^* = − 13 to −17 . The antireflection film according to claim 1, wherein the anchor layer has a thickness of 3 nm to 7 nm. The antireflection film according to claim 1, wherein the hard coat layer includes an acrylic active energy ray-curable resin.

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