JPH10123302A - Antireflection film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain antireflection performance in the same level as that of an antireflection film having a conventional four-layer structure by forming a three-layer structure comprising a high refractive index material layer, a low refractive index material layer and a specified medium refractive index material layer. SOLUTION: This antireflection film has a laminated structure of an antireflection film 2 on a base body 1, and the antireflection film 2 is a multilayered film comprising, from the base body 1, a medium refractive index material layer 2a, a high refractive index layer 2b and a low refractive index material layer 2c. As for the medium refractive index material layer 2a, a layer containing aluminum oxide and lanthanum oxide or an aluminum- lanthanum double oxide layer is used. By forming the three-layer structure, one process of forming a film can be omitted without decreasing the antireflection performance compared to an antireflection film of a conventional four-layer structure, and as a result, the production cost of the antireflection film can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antireflection film for preventing reflection of light on the surface of an image display device such as a CRT or a liquid crystal display.

[0002]

2. Description of the Related Art Hitherto, in order to prevent reflection of external light on the surface of various image display devices, an antireflection film has been applied to the surface of the image display device.

As shown in FIG. 3, a hard coat layer 32 for imparting abrasion resistance to an anti-reflection film, an anti-reflection film 33, and A structure in which a water-repellent layer 34 for imparting water resistance to an anti-reflection film is sequentially formed in accordance with the requirements is widely used. Here, as the antireflection film 33,
From the hard coat layer 32 side, the high refractive index material layer 33a (33
c) and the low refractive index material layer 33b (3
3d) has been proposed to use a multilayer film in which a total of four layers (each two layers) are alternately laminated (Japanese Patent Laid-Open No. 62-21).
No. 5202). In this case, as the high refractive index material,
The refractive index of titanium dioxide or zirconium dioxide is 2.0
The above inorganic materials are used. As the low refractive index material, silicon dioxide, aluminum oxide or the like having a refractive index of 1.
Six or less inorganic materials are used. Then, the high-refractive-index material layer 33a and the low-refractive-index material layer 3 are arranged such that the reflectance is about 0.5% at a wavelength λ of 500 to 650 nm.
The thickness of 3b is adjusted to about λ / 8, and the thickness of the high refractive index material layer 33c and the low refractive index material layer 33d is set to λ / 8.
It is adjusted to about / 4.

[0004]

However, when the anti-reflection film has a four-layer structure as described above, the anti-reflection film can be given good anti-reflection properties. In addition, a dry process such as a vacuum evaporation method or a sputtering method, which has a relatively high film formation cost, must be performed at least four times, and the number of dry processes must be reduced without lowering the antireflection property (ie, the reflection (Reducing the number of constituent layers of the protective film) has been desired. Further, the antireflection ability of the antireflection film also depends on the optical thickness of each layer constituting the antireflection film {= n (refractive index) × d (layer thickness)}, so that it is necessary to control it with considerable accuracy. However, it is difficult to control four layers having a thickness on the order of about 10 to 150 nm, and from this viewpoint, it has been desired to reduce the number of constituent layers of the antireflection film.

[0005] In response to such a demand, in order to make the number of constituent layers of the antireflection film into a three-layer structure, the hard coat layer side
An antireflection film comprising a medium refractive index material layer having a refractive index of 1.7 to 1.8 and a high refractive index material layer having a refractive index of 2.0 or more is further provided on the high refractive index material layer. It is known in principle that a low refractive index material layer having a thickness of 1.6 or less is laminated. However, at present, there is no known single refractive index material having such a numerical range. Therefore, an attempt was made to form a film by mixing titanium dioxide generally used as a high refractive index material and silicon dioxide generally used as a low refractive index material, but a uniform film was obtained. Therefore, there was a problem that the intended refractive index was not obtained.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to reduce the number of layers constituting the antireflection film to less than 4 so as not to lower the antireflection ability of the antireflection film. With the goal.

[0007]

SUMMARY OF THE INVENTION The present inventor has heretofore been unable to use either a high refractive index material (refractive index of 2.0 or more) or a low refractive index material (refractive index of 1.6 or less). Lanthanum oxide having a refractive index of 1.9 and aluminum oxide having a refractive index of 1.6 can be simultaneously formed under the same film forming conditions by a co-evaporation method or the like, and the obtained film has a refractive index substantially intermediate between them. And found that the present invention was completed.

That is, the present invention relates to an antireflection film having a multilayer antireflection film provided on a substrate, wherein the multilayer antireflection film contains a layer containing aluminum oxide and lanthanum oxide or an aluminum-lanthanum composite oxide. The present invention provides an antireflection film comprising a medium refractive index material layer comprising a layer.

In the antireflection film of the present invention, it is particularly preferable that the multilayer antireflection film has a three-layer structure comprising a medium refractive index material layer, a high refractive index material layer, and a low refractive index material layer from the substrate side. . Further, it is preferable to further form a hard coat layer between the substrate and the antireflection film in order to improve mechanical properties such as abrasion resistance of the antireflection film. Further, in order to improve the water resistance of the antireflection film, it is preferable to further form a water-repellent layer on the antireflection film.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a basic embodiment of the antireflection film of the present invention. Also, FIGS. 2A and 2B
FIG. 3 is a cross-sectional view of another embodiment of the antireflection film of the present invention.

The anti-reflection film of FIG. 1 has a structure in which an anti-reflection film 2 is laminated on a substrate 1. Here, the antireflection film 2 is a multilayer film having a structure in which a medium refractive index material layer 2a, a high refractive index material layer 2b, and a low refractive index material layer 2c are stacked from the substrate 1 side. And this medium refractive index material layer 2
As a, a layer containing an aluminum oxide and a lanthanum oxide or an aluminum-lanthanum composite oxide layer is used.

By adopting such a three-layer structure, it is possible to reduce one film-forming step without lowering the anti-reflection ability as compared with the conventional anti-reflection film having a four-layer structure. Film production costs can be reduced.

In the present invention, the substrate 1 may be the same as the substrate used in the conventional antireflection film, and may be a film-like glass or a light-transmitting plastic film such as polycarbonate. Films, triacetyl cellulose films, polyethersulfone films, polymethyl acrylate films, polyethylene terephthalate films, and the like can be used.

The type, thickness, light transmittance and the like of the substrate 1 can be appropriately selected according to the intended use of the antireflection film.

As described above, the medium refractive index material layer 2a is a layer containing aluminum oxide (refractive index 1.6) and lanthanum oxide (refractive index 1.9), or
A lanthanum composite oxide layer is used.

Here, the layer containing aluminum oxide and lanthanum oxide is represented by (Al ₂ O ₃ ) _a (La ₂ O ₃ ) _{b where} a and b are moles. This is a layer composed of a mixture. This mixture is microstructurally characterized by A
Although l ₂ O ₃ and La ₂ O ₃ are present independently, they exhibit an optically uniform refractive index. Further, by changing the numerical values of a and b, an arbitrary refractive index in the range of 1.6 to 1.9 can be selected. This layer can be formed by a physical vapor deposition method such as a vacuum vapor deposition method, an ion plating method, and a sputtering method.

The aluminum-lanthanum composite oxide layer is a compound represented by (La _x Al _y O _z )
x = 0.5 to 1, y = 1 to 1.5, and z = 3. ) And has an optically uniform refractive index. Also,
By changing the numerical values of x, y and z, 1.6 to
Any refractive index in the range of 1.9 can be selected.
This layer can be formed by a physical vapor deposition method such as a vacuum vapor deposition method, an ion plating method, and a sputtering method.

As the high refractive index material constituting the high refractive index material layer 2b, a material having a refractive index exceeding 1.9 is used.
Such materials include titanium dioxide, zirconium dioxide, tantalum dioxide, zinc oxide, indium oxide,
Examples include hafnium oxide, cerium oxide, and tin oxide.

The thickness of the high-refractive-index material layer 2b is λ / 2 in consideration of productivity, flexibility, film configuration, and the like.
It is preferable to set the degree.

As the low refractive index material constituting the low refractive index material layer 2c, a material having a refractive index of 1.6 or less is used. As such a material, silicon dioxide, magnesium fluoride, calcium fluoride, cerium fluoride, aluminum fluoride, aluminum oxide, or the like can be used.

The thickness of the low-refractive-index material layer 2c is preferably about λ / 4 in consideration of productivity, flexibility and the like.

FIG. 1 shows an anti-reflection film comprising a substrate 1 and an anti-reflection film 2. The anti-reflection film of the present invention, as shown in FIG. Between the anti-reflection film and the anti-reflection film 2,
Hard coat layer 3 to prevent peeling of antireflection film 2
Is preferably provided. Furthermore, it is preferable to provide a water-repellent layer 4 on the anti-reflection film 2 as shown in FIG.

In the present invention, the hard coat layer 3 may be formed of a light-transmitting material similar to the hard coat layer used in the conventional antireflection film. For example, an ultraviolet curable acrylic resin or silicone resin can be used.

The refractive index of the hard coat layer 3 is made lower than the refractive index of the medium refractive index material layer 2a. Thereby, the antireflection property of the antireflection film 2 can be improved. Further, it is preferable that the refractive index of the hard coat layer 3 is set to be substantially the same as that of the substrate 1 for anti-reflection characteristics.

The thickness of the hard coat layer 3 is hardness,
From the viewpoint of productivity and the like, the thickness of the shape is preferably 3 to 10 μm.

As the water-repellent layer 4, a layer formed of the same hydrophobic material as the water-repellent layer used in the conventional antireflection film can be used. For example, perfluorosilane, fluorocarbon and the like can be mentioned.

Next, the method for producing the antireflection film of the present invention will be described with reference to the antireflection film of the embodiment shown in FIG.

First, a resin composition for forming a hard coat layer is applied on a substrate 1 by a microgravure coater.
The hard coat layer 3 is formed by drying.

Next, a medium refractive index material such as a layer containing aluminum oxide and lanthanum oxide or an aluminum-lanthanum composite oxide layer is deposited on the hard coat layer 3 by an ion plating method or the like. The refractive index material layer 2a is formed.

Next, a high-refractive-index material is deposited on the medium-refractive-index material layer 2a by a vacuum deposition method, a sputtering method, or the like to form a high-refractive-index material layer 2b.

Next, a low-refractive-index material layer 2c is formed on the high-refractive-index material layer 2b by a vacuum deposition method, a sputtering method, or the like.

Finally, FIG. 2 (b) is formed by using a low refractive index material.
Can be produced.

[0034]

The present invention will be described below in more detail with reference to examples.

Comparative Example 1 80 μ of Refractive Index n = 1.489 at λ = 550 nm
m-thick triacetyl cellulose substrate (Fujitac (80
μm thickness), manufactured by Fuji Film Co., Ltd.).
Is deposited by a conventional method to form a high-refractive-index material layer having a thickness of λ / 8, and a refractive index n = 1.45 thereon.
To form a low-refractive-index material layer having a thickness of λ / 8, and titanium dioxide having a refractive index of n = 2.2 is again deposited thereon by a conventional method to form a high-refractive-index material layer at λ / Then, silicon dioxide having a refractive index of n = 1.45 was deposited thereon to form a low-refractive-index material layer having a thickness of λ / 8 to obtain a conventional antireflection film.

The spectral reflection characteristics of the obtained antireflection film were measured using a spectrophotometer. FIG. 5 shows the obtained results.
Shown in As is apparent from this figure, 475-625n
m, the reflectance is 0.3% or less over the range of m.
Excellent antireflection properties were exhibited.

Example 1 80 μ of Refractive Index n = 1.489 at λ = 550 nm
m-thick triacetyl cellulose substrate (Fujitac (80
μm thick), on the Fuji Film Co., Ltd.), Al ₂ O ₃ and La ₂
O ₃ was ion-plated so that the refractive index n was 1.77 to form a medium refractive index material layer with a thickness of λ / 4.

The refractive index n = 2.2 on the medium refractive index material layer.
Is deposited by a conventional method to form a high-refractive-index material layer with a thickness of about λ / 2, and further thereon a refractive index n = 1.4.
5 of silicon dioxide to reduce the low refractive index material layer to about λ /
It was formed in a thickness of 4 to obtain an antireflection film.

FIG. 4 shows the spectral reflection characteristics of the obtained antireflection film. As is clear from FIG.
The reflectance is 0.3% or less over a range of 5 to 675 nm), which is wider than the spectral reflection characteristics (FIG. 5) of a conventional antireflection film having one more antireflection layer (Comparative Example 1). Excellent antireflection properties were exhibited.

Example 2 80 μ of Refractive Index n = 1.489 at λ = 550 nm
m-thick triacetyl cellulose substrate (Fujitac (80
A coating solution containing an acrylic resin was applied by a conventional method, and dried to form a 7 μm-thick hard coat layer having a refractive index of n = 1.50.

On this hard coat layer, Al ₂ O ₃ and La
₂ O ₃ was ion-plated so that the refractive index n was 1.77 to form a medium refractive index material layer having a thickness of λ / 4.

The refractive index n = 2.2 on the medium refractive index material layer.
To form a high-refractive-index material layer with a thickness of λ / 2, and further have a refractive index n = 1.45.
Was deposited to form a low-refractive-index material layer with a thickness of 4 / λ to obtain an antireflection film.

The spectral reflection characteristics of the obtained antireflection film were excellent as in Example 1. Moreover, the peel resistance of the antireflection layer was also improved.

Example 3 A perfluorosilane (KBM) was further formed on the low refractive index material layer.
-7803, manufactured by Shin-Etsu Chemical Co., Ltd.) to form an anti-reflection film in the same manner as in Example 2, except that a water-repellent layer was formed.

The obtained anti-reflection film exhibited the same anti-reflection characteristics as in Example 1, and was excellent in water repellency and fingerprint wiping properties.

[0046]

The antireflection film of the present invention has a three-layer antireflection film composed of a high-refractive-index material layer, a low-refractive-index material layer, and a specific medium-refractive-index material layer. Has the same level of antireflection performance as an antireflection film having an antireflection film. Therefore, when producing the antireflection film of the present invention, the number of film forming steps can be reduced without lowering the antireflection performance, and the production cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a basic embodiment of the antireflection film of the present invention.

FIG. 2 is a cross-sectional view of another embodiment of the antireflection film of the present invention (FIGS. (A) and (b)).

FIG. 3 is a cross-sectional view of a conventional antireflection film.

FIG. 4 is a spectral reflection characteristic diagram of the antireflection film of Example 1.

FIG. 5 is a spectral reflection characteristic diagram of the antireflection film of Comparative Example 1.

[Explanation of symbols]

 Reference Signs List 1 base material 2 antireflection film 3 hard coat layer 4 water repellent layer

Claims (4)

[Claims] An anti-reflection film having a multilayer anti-reflection film provided on a substrate, wherein the multi-layer anti-reflection film comprises a layer containing aluminum oxide and lanthanum oxide or an aluminum-lanthanum composite oxide layer. An anti-reflection film comprising a refractive index material layer. 2. A multilayer antireflection film comprising a medium refractive index material layer, a high refractive index material layer, and a low refractive index material layer from the substrate side.
The antireflection film according to claim 1, which has a layer structure. 3. The antireflection film according to claim 1, wherein a hard coat layer is further formed between the substrate and the antireflection film. 4. The anti-reflection film according to claim 3, wherein a water-repellent layer is further formed on the anti-reflection film.