JP2000338307A - Antireflection film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a film having excellent antireflection property, adhesion property of an antireflection layer with a base body, and durability by forming low refractive index layers from silica containing methyl groups in the layer by a plasma CVD method and forming high refractive index layers from metal oxides by a plasma CVD method. SOLUTION: The low refractive index layers consist of silica containing methyl groups in the layer formed by a plasma CVD method, while the high refractive index layers consist of metal oxides formed by a plasma CVD method. The antireflection film consists of alternately laminated high refractive index layers and low refractive index layers from the air side on a transparent base sheet with a hard coat layer interposed. The order and thickness of layers are specified such that the first layer is a low refractive index layer of 80 to 110 nm thickness, the second layer is a high refractive index layer of 70 to 90 nm thickness, the third layer is a low refractive index layer of 35 to 55 nm thickness, the fourth layer is a high refractive index layer of 10 to 30 nm thickness and the fifth layer is a low refractive index layer of 35 to 55 nm thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-reflection film having excellent anti-reflection properties and excellent adhesion and durability of an anti-reflection layer to a substrate.

[0002]

2. Description of the Related Art Conventionally, transparent substrates such as glass and plastic have been used for displays such as curved mirrors, rearview mirrors, goggles, window glasses, personal computers, word processors, and various other commercial displays. When observing the visual information of objects, characters, figures, etc. through these transparent substrates, or the image from the mirror through the transparent substrate and observing the image from the reflective layer, the surface of these transparent substrates reflects light, There is a problem that the necessary visual information is difficult to read.

Conventionally, there has been a technique for preventing the reflection of light.
Applies anti-reflective paint to glass and plastic surfaces
0.1μm thick on the surface of a transparent substrate such as glass
About MgF_TwoA method of providing an ultra-thin or metal-deposited film such as
Ionizing radiation curable resin on the surface of plastic lenses, etc.
Coating, and then depositing SiO _XAnd MgF_TwoMembrane
Forming a cured film of ionizing radiation curable resin
Further, there has been a method of forming a coating film having a low refractive index.

[0004]

In the above, an antireflection film obtained by laminating a transparent inorganic thin film on a transparent substrate to provide an antireflection function has excellent antireflection properties, but the base material is particularly transparent plastic. In the case of a sheet (in which a hard coat layer may be formed), there is a problem in the adhesion of the antireflection layer to the base material, and the flexibility between the base material and the antireflection layer is different. The anti-reflection layer cannot follow the flexibility of the base material, and the anti-reflection layer suffers from fine cracks, the anti-reflection layer is partially peeled off, and the uniformity of the anti-reflection property is impaired. There was a gender problem. Accordingly, an object of the present invention is to provide an anti-reflection film having excellent anti-reflection properties and also having excellent adhesion and durability of an anti-reflection layer to a substrate.

[0005]

The above object is achieved by the present invention described below. That is, the present invention is an antireflection film in which a high refractive index layer and a low refractive index layer are alternately laminated in the following order and thickness from the air side on a transparent base sheet via a hard coat layer. An antireflection film, wherein the low-refractive-index layer is formed by a plasma CVD method and is made of silica containing a methyl group in the layer, and the high-refractive-index layer is made of a metal oxide formed by the plasma CVD method. I will provide a. First layer: Low refractive index layer 80 to 110 nm Second layer: High refractive index layer 70 to 90 nm Third layer: Low refractive index layer 35 to 55 nm Fourth layer: High refractive index layer 10 to 30 nm Fifth layer: Low refractive index Rate layer 35-55 nm

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to the drawings showing preferred embodiments. As shown in FIG. 1, the antireflection film of the present invention has a hard coat layer and an antireflection layer formed in this order on a transparent base sheet. It is characterized by having.

A preferred embodiment of the present invention is as follows. (1) The refractive index of the low refractive index layer is 1.42 to 1.51, and the refractive index of the high refractive index layer is 1.78 to 2.4.
The antireflection film as described above. (2) The metal oxide constituting the high refractive index layer is Ti
The above antireflection film, which is at least one selected from O ₂ , SnO ₂ , In ₂ O ₃ , ZrO ₂ and a mixed oxide thereof. (3) The antireflection film, wherein the metal oxide is formed by a plasma CVD method using an alkoxide of the metal. (4) The antireflection film as described above, wherein the low refractive index layer contains a methyl group in a ratio of carbon atom / silicon atom = 0.1 to 0.2 in terms of element. (5) The above-described antireflection film, wherein the high refractive index layer contains an organic substance in a ratio of carbon atoms / metal atoms (excluding silicon) = 0.1 to 0.2 in terms of elements. (6) The low refractive index layer is formed by plasma C using hexamethyldisiloxane or tetramethyldisiloxane as a source gas.
The above antireflection film, which is a silica layer formed by a VD method.

Next, the constituent materials and the manufacturing method of the antireflection film of the present invention will be described. The transparent substrate sheet used in the present invention is formed from a stretched or unstretched film of ceramic such as glass or a transparent plastic. In addition to ordinary optical glass, as a transparent plastic, for example, polyester, polyamide, polyimide,
A thermoplastic resin sheet or film of polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, polymethyl methacrylate, polycarbonate, polyurethane or the like can be used. The transparent substrate sheet may be provided with a primer layer or an adhesive layer in order to strengthen the adhesion with the hard coat layer formed thereon. These base sheets have a thickness of generally 50 to 300 μm, although they vary depending on the use and the material.

The hard coat layer provided on the substrate sheet is usually formed from a thermosetting resin and / or an ionizing radiation type resin. A hard coat layer is formed by applying and curing an uncured coating solution containing these resins on a transparent substrate sheet using a conventionally known coating method. The coating liquid has a thickness of the hard coat layer of preferably 0.5
To 6 μm, more preferably 3 to 6 μm. If the thickness is too small, it is difficult to maintain the hardness of the antireflection layer formed on the transparent substrate sheet, and
By setting it to the range of m, it is possible to maintain good hardness, and it is possible to impart hard performance to the antireflection film. Making the hard coat layer unnecessarily thick not only impairs the flexibility of the antireflection film, but also increases the curing time during its formation, lowers productivity, and increases manufacturing costs. It is not preferable.

In the present invention, the hard coat layer, the adhesive layer or the primer layer can be provided with fine irregularities for the purpose of imparting anti-glare properties to the obtained anti-reflective film in addition to excellent anti-reflective properties. . The hard coat layer (irregular shape) is in direct contact with the antireflection layer,
The refractive index of the hard coat layer is formed smaller than the refractive index of the antireflection layer. In the present invention, "hard performance"
Alternatively, “hard coat” means that a pencil hardness test shown in JIS K5400 shows a hardness of H or more.

Preferable thermosetting resins and / or ionizing radiation type resins for forming a hard coat layer satisfying the above requirements (these are sometimes collectively referred to as reaction curable resins in the present invention). For example, those having an acrylate functional group, for example, relatively low molecular weight polyester, polyether, acrylic resin, epoxy resin, polyurethane, alkyd resin, spiro acetal resin, polybutadiene, polythiol polyene resin,
Oligomers or prepolymers such as (meth) acrylates of polyfunctional compounds such as polyhydric alcohols (hereinafter, acrylate and methacrylate are referred to as (meth) acrylates) and ethyl as a reactive diluent ( Monofunctional monomers such as (meth) acrylate, ethylhexyl (meth) acrylate, styrene, vinyltoluene, and N-vinylpyrrolidone; and polyfunctional monomers such as trimethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate, Propylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acryl Over bets, it is used that relatively large amounts include neopentyl glycol di (meth) acrylate.

Further, when the above-mentioned ionizing radiation-curable resin is used as an ultraviolet-curable resin, examples of the photopolymerization initiator include acetophenones, benzophenones, Michler benzoyl benzoate, α-amyloxime. It is preferable to use a mixture of an ester, a thioxanthone, or n-butylamine, triethylamine, tri-n-butylphosphine, or the like as a photosensitizer.

The above-mentioned ionizing radiation-curable resin includes a reactive organosilicon compound represented by the general formula R _m Si (OR ′) _n (where R and R ′ are alkyl groups having 1 to 10 carbon atoms). And m + n = 4, and m and n are each an integer.). Examples of the silicon compound include tetramethoxysilane, tetraethoxysilane, tetra-iso-propoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane, tetra-sec-butoxysilane, tetra-ter
t-butoxysilane, tetrapentaethoxysilane, tetrapenta-iso-propoxysilane, tetrapenta-n-propoxysilane, tetrapenta-n-butoxysilane, tetrapenta-sec-butoxysilane, tetrapenta-tert-butoxysilane, methyltrimethoxysilane, Methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethylethoxysilane, dimethylmethoxysilane, dimethylpropoxysilane, dimethylbutoxysilane, methyldimethoxysilane, methyldiethoxysilane, Xyltrimethoxysilane and the like.

In the present invention, an antireflection layer having durability such as adhesion and bending resistance is formed on the surface of the hard coat layer formed as described above. As shown in FIG. 2, the antireflection layer includes a high-refractive-index layer and a low-refractive-index layer, as viewed from the air side.
Layer: high refractive index layer = 70 to 90 nm, third layer: low refractive index layer = 35 to 55 nm, fourth layer: high refractive index layer = 10 to 30
nm and fifth layer: low-refractive-index layer = 35 to 55 nm in this order laminated on the surface of the hard coat layer.

In the above, the reason why the number of layers is five is that
This is the minimum number of layers required to obtain the optical characteristics required as an anti-reflection film, and when the number of layers is 6 or more, the productivity of the anti-reflection film is low, and is insufficient.
Further, the reason for setting the thickness of each layer to the above range is a film thickness range allowable to obtain the optical characteristics required as an antireflection film, and when the thickness of each layer deviates from the above range, the thickness required for the antireflection film is required. It is insufficient in that optical characteristics cannot be obtained. The total thickness of the five layers is 230
It is preferably in the range of ３340 μm.

The low refractive index layer is formed by a plasma CVD method, and is formed such that the layer to be formed contains silica in which a methyl group derived from an alkoxide remains. In order to form a low refractive index layer using a plasma CVD method so that a methyl group remains in a layer, an organic silicon compound containing a methyl group is used as a source gas, and a film to be deposited is maintained at a temperature as low as possible. It is preferable to perform the plasma CVD under the condition that no other inorganic evaporation source is present. The amount of methyl groups in the formed layer is such that the carbon atoms / silicon atoms in terms of the element as a whole of the low-refractive-index layer are 0.1 to 0.
A ratio of 2 is preferred. If the amount of the methyl group is less than the above range, the antireflection layer is insufficient in that the brittleness is liable to be cracked and the flexibility is low, and on the other hand, if the amount exceeds the above range, the antireflection layer is colored yellow-brown, It is insufficient in that transparency is lost. By including a methyl group in the low-refractive-index layer as described above, the adhesion of the low-refractive-index layer to another layer is improved, and the flexibility of the antireflection layer is improved, and the antireflection film is bent. Cracks occur in the anti-reflective layer,
The disadvantage of flaking is improved.

As the organosilicon compound having a methyl group used for forming the low refractive index layer, for example, hexamethyldisiloxane (HMDSO), tetramethyldisiloxa (TMDSO), octamethyltetrasiloxane, tetramethoxysilane ( TMOS), tetraethoxysilane (TEOS), methyltrimethoxysilane, methylsilane, dimethylsilane, trimethylsilane, tetramethylsilane and the like. Among them, the characteristics of the silica film formed especially, the material of the organosilicon compound HMDSO, TMDSO, TEOS and TMOS are preferably used from the viewpoints of handleability and cost.

On the other hand, the metal oxide constituting the high refractive index layer
For example, for example, ZnO having a refractive index of 1.5 or more (refractive index
1.90, the following values indicate the refractive index), TiO_Two(2.
3-2.7), CeO_Two(L.95), Sb_TwoO_Five,
(1.71), SnO _Two(1.997), ITO (1.
95), In _TwoO _Three(2.00), Y_TwoO_Three(1.87),
La_TwoO_Three(1.95), Al_TwoO_Three(1.63), HfO
_Two(2.00), ZrO_Two(2.05) and the like.
Among them, gold having a refractive index of 1.78 to 2.4 is particularly preferable.
Oxides are preferred, especially TiO._Two, SnO_Two, In
_TwoO_Three, ZrO_TwoAnd mixed oxides thereof.
Good.

The high-refractive-index layer made of a metal oxide as described above is formed from a plasma C using an alkoxide of the metal as a raw material.
Preferably, it is formed by a VD method. Also, plasma CVD
By appropriately setting the conditions of the method, the high refractive index layer to be formed is converted into carbon atoms /
It is preferable to contain an organic substance derived from an alkoxide at a ratio of metal atoms (excluding silicon) = 0.1 to 0.2. If the amount of the organic substance is less than the above range, it is brittle and easily cracked, and it is insufficient in terms of lacking flexibility, etc. On the other hand, if it exceeds the above range, the antireflection layer is colored yellow-brown, This is insufficient in that a required refractive index cannot be obtained. By including an organic material in the high refractive index layer in this manner, the adhesion of the high refractive index layer to other layers is improved, and the flexibility of the antireflection layer is improved, so that the antireflection film is bent. In addition, the defect that the antireflection layer is cracked or peels off is improved.

Examples of the metal alkoxide used for forming the high refractive index layer include titanium tetraisopropoxide, titanium tetra-n-butoxide, zirconium-t-butoxide, zirconium-n-butoxide, and zirconium-n-propoxide. , Tetra-t-
Butoxytin, hafnium ethoxide, cerium-t-
Butoxide, antimony-n-butoxide and the like.

One example of a preferred method for producing the antireflection film of the present invention is as follows. First, an uncured hard coat layer made of a curing reaction type resin is formed on a transparent substrate sheet, and after laminating and shaping a mat-shaped shaping film having fine irregularities thereon as necessary, The hard coat layer is cured by heat treatment and / or ionizing radiation treatment. Next, the above-mentioned imprinting film is peeled off and removed from the hardened hard coat layer to form fine irregularities on the surface of the hard coat layer. Next, plasma C is applied on the hard coat layer.
Using the VD method and necessary source gases, the fifth, fourth, third, second, and first layers are sequentially laminated as shown in FIG. 2 to obtain the antireflection film of the present invention. . In the above, the formation of the fine unevenness is not essential.

The anti-reflection film of the present invention obtained as described above is an anti-reflection film having excellent anti-reflection properties and excellent adhesion and durability of the anti-reflection layer to the substrate. A polarizing plate laminated with the element,
A clear image without reflected light can be displayed on a liquid crystal display device incorporating this polarizing plate. Also, a clear image without reflection can be displayed on a cathode ray tube having the antireflection film of the present invention bonded to the surface.

[0023]

Next, the present invention will be described more specifically with reference to examples and comparative examples. Example 1 A-4350 (a biaxially stretched polyethylene terephthalate film having a thickness of 188 µm: manufactured by Toyobo Co., Ltd.), which is a transparent base sheet, was coated with a hard coat resin (PET-D31).
Concentration of 37% by weight with toluene
After dilution, coating and drying, cured by ionizing radiation,
A hard coat layer having a thickness of 7.5 μm was formed. Using a roll-type plasma CVD apparatus, a silica layer and a titanium oxide layer were alternately laminated on the hard coat layer in a total of five layers under the following conditions to form an antireflection layer, thereby obtaining an antireflection film of the present invention. Incidentally, hexamethyldisiloxane (HNDSO) was used for forming the silica layer, and titanium tetraisopropoxide was used for forming the titanium oxide layer.

[0024]

The sample obtained in Example 1 was
When analyzed by TIR, a peak derived from Si—CH ₃ was detected at around 1260 cm ⁻¹ . CH ₃ −
A peak derived from C-CH ₃ was detected at around 1100 cm ⁻¹ . Incidentally, the refractive index of the silica layer is 1.451,
The refractive index of the titanium oxide layer was 2.001. Also, XP
The carbon content of each layer was measured by S.
As described.

Example 2 A total of five silica layers and titanium oxide layers were alternately laminated on the same hard coat layer as in Example 1 using a roll plasma CVD apparatus in the same manner as in Example 1 under the following conditions. An anti-reflection layer was formed to obtain an anti-reflection film of the present invention.
Note that TMDSO was used for forming the silica layer, and titanium tetraisopropoxide was used for forming the titanium oxide layer.

[0027]

The sample obtained in Example 2 was
When analyzed by TIR, a peak derived from Si—CH ₃ was detected at around 1260 cm ⁻¹ . Also, CH ₃
Peak derived from -C-CH ₃ was detected around 1100 cm ^-1. The refractive index of the silica layer was 1.451, and the refractive index of the titanium oxide layer was 2.001. or,
When the carbon content of each layer was measured by XPS, it was as shown in Table 2 above.

Comparative Example 1 In Example 1, an ITO layer 2 was formed on the hard coat layer formed on the base sheet of Example 1 by a sputtering method.
5 nm, SiO ₂ layer 25 nm, ITO layer 85 nm and S
An iO ₂ layer of 92 nm was laminated in this order to obtain an antireflection film of a comparative example. When the sample obtained by this comparative example was analyzed by FTIR, a peak derived from an organic substance was not obtained. No carbon content was detected by XPS. The silica layer had a refractive index of 1.4.
52 and the refractive index of the ITO layer was 2.002.

Evaluation 1. Adhesiveness Each of the antireflection films obtained in Examples and Comparative Examples was subjected to a cellophane tape peeling test of the antireflection layer after being left in an environment of 50 ° C./95% relative humidity for 48 hours. Cellophane tape peel test was conducted by Nichiban Co., Ltd.
5 x 10 x 10 cross-cuts using scotch tape
The peeling test was performed twice, and the average value was obtained. 2. Flex resistance test Each antireflection film obtained in each of Examples and Comparative Examples was tested in accordance with JIS K5400.
A stainless rod having a diameter of 10 mm was used for winding the antireflection film. As a result of the test, x indicates that a fine crack was generated in the antireflection layer, and x indicates that no change was observed.

3. Carbon atom / metal atom (excluding silicon) ratio Each antireflection film obtained in each of Examples and Comparative Examples was measured by XPS analysis. 4. Carbon atom / silicon atom ratio The respective antireflection films obtained in Examples and Comparative Examples were measured by XPS-IR analysis. 5. Measurement of reflectance The reflectance was measured for each of the antireflection films obtained in Examples and Comparative Examples. The result is shown in FIG.
Shown in The above results are shown in Table 3 below.

[0032]

[0033]

According to the present invention, it is possible to provide an anti-reflection film which is excellent in anti-reflection property, and excellent in adhesion and durability of an anti-reflection layer to a substrate sheet.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a basic layer configuration of an antireflection film of the present invention.

FIG. 2 is a cross-sectional view illustrating an example of an antireflection layer.

FIG. 3 is a cross-sectional view showing reflectance spectra of antireflection films of Examples and Comparative Examples.

 ────────────────────────────────────────────────── ─── Continued on the front page F-term (reference) 2K009 AA08 AA15 BB14 BB22 BB24 CC01 CC03 CC45 DD04 EE00 4F100 AA17C AA20D AA21C AA27C AA28C AH06D AK42 BA04 BA10A BA10D BA26 CC00B EJ38 JJJNJJJNJJJNJJN

Claims (7)

[Claims] 1. An antireflection film comprising a high refractive index layer and a low refractive index layer alternately laminated in the following order and thickness from the air side on a transparent substrate sheet via a hard coat layer. An antireflection film, wherein the low refractive index layer is formed by a plasma CVD method and made of silica containing a methyl group in the layer, and the high refractive index layer is made of a metal oxide formed by the plasma CVD method. First layer: Low refractive index layer 80 to 110 nm Second layer: High refractive index layer 70 to 90 nm Third layer: Low refractive index layer 35 to 55 nm Fourth layer: High refractive index layer 10 to 30 nm Fifth layer: Low refractive index Rate layer 35-55 nm 2. The low refractive index layer has a refractive index of 1.42 or more.
1.51, and the refractive index of the high refractive index layer is 1.7.
The anti-reflection film according to claim 1, wherein the thickness is 8 to 2.4. 3. The metal oxide constituting the high refractive index layer is at least one selected from TiO ₂ , SnO ₂ , In ₂ O ₃ , ZrO ₂ and a mixed oxide thereof. Anti-reflection film. 4. The antireflection film according to claim 3, wherein the metal oxide according to claim 3 is formed by a plasma CVD method using an alkoxide of the metal. 5. The method according to claim 1, wherein the low refractive index layer has carbon atoms / element conversion.
2. The antireflection film according to claim 1, wherein the silicon atom contains methyl groups in a ratio of 0.1 to 0.2. 6. The method according to claim 1, wherein the high refractive index layer comprises carbon atoms /
The antireflection film according to claim 1, comprising an organic substance in a ratio of metal atoms (excluding silicon) = 0.1 to 0.2. 7. The antireflection film according to claim 1, wherein the low refractive index layer is a silica layer formed by a plasma CVD method using hexamethyldisiloxane or tetramethyldisiloxane as a source gas.