JP2003062920A - Antireflection film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an antireflection film having good reflectivity characteristics and an excellent alkali resistance. SOLUTION: The antireflection film comprises an antireflection layer 20 having at least 3-layer laminate in which layers having different refractive indexes are alternatively laminated on a base 3. In this film, the low refractive index layer 13 of a position farthest from the base 3 of the layers for constituting the layer 20 is formed of an oxide alloy layer containing Si and Zr.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an antireflection film that suppresses surface reflection of a display or the like.

[0002]

2. Description of the Related Art For example, in a CRT (cathode ray tube) or an LCD (liquid crystal display), there is a problem that the displayed image becomes difficult to see because the external light is reflected on the surface of the screen. On the other hand, the potential of the screen surface changes due to the high voltage applied during image display, which may cause dust or dirt to adhere to the screen surface, or a discharge phenomenon may occur to a person approaching the screen. . In order to prevent the occurrence of such a phenomenon, the technology of forming an anti-reflection film on the surface of the screen is applied in order to give the screen surface an antistatic function and further to provide an electromagnetic radiation shielding function. There is.

Conventionally, a film having an anti-reflection (anti-reflection, hereinafter abbreviated as AR) function is attached to the screen surface of a CRT or LCD to prevent reflection of external light on the screen surface. Or
The screen is made easier to see by avoiding the reflection of external light. Furthermore, the contrast is increased to improve the image quality, and the transmittance is increased to improve the screen brightness. Also, by forming a conductive layer in the antireflection film to have an antistatic effect and an electromagnetic shielding effect, it is possible to prevent dust and dirt from adhering to the screen surface and to avoid adverse effects on the human body. ing.

Antireflection films for use in CRTs are disclosed, for example, in JP-A-11-218603 and JP-A-9-80.
205, and H.M. Ishikawa et a
l. / Thin Solid Films 351
(1999) 212-215. These are PET (polyethylene terephthalate)
A hard coat layer is formed on the substrate, and SiO _x / ITO / SiO ₂ / ITO / SiO ₂ or SiO _{x is} further formed on the hard coat layer.
It has a structure in which an AR layer having a laminated structure such as / TiN / SiO ₂ is formed.

On the other hand, as for the antireflection film formed on the LCD surface, for example, "optical thin film" (HA Ma.
Cleod, Nikkan Kogyo Shimbun Co., Ltd., etc., having a constitution in which a substrate / high refractive index layer / low refractive index layer / high refractive index layer / low refractive index layer are laminated, and substrate / medium refractive index layer / high A structure having a laminated structure of a refractive index layer / a low refractive index layer is disclosed. Industrially, on the basis of these constitutions, practical use is made by forming an adhesion layer to improve the adhesion between the substrate and the antireflection layer, or by providing an antifouling layer or the like on the outermost surface. It is increasing the nature.

[0006]

Many of the above-mentioned conventionally used antireflection films have a low refractive index layer as the uppermost layer constituting the antireflection layer formed on the substrate. A SiO ₂ film is formed. However, since SiO ₂ has poor alkali resistance, it is necessary to improve the alkali resistance of the antireflection film.
Especially in LCD, since the step of attaching the antireflection film to the polarizing plate is performed in an alkaline environment,
It is important to improve the alkali resistance properties of antireflection films.

It is an object of the present invention to provide an antireflection film having a high alkali resistance while ensuring an excellent antireflection function by addressing the above problems of the prior art.

[0008]

SUMMARY OF THE INVENTION The present invention relates to an antireflection film having an antireflection layer formed by alternately laminating at least three layers having different refractive indexes on a substrate. Of the constituent layers, the layer farthest from the substrate is formed of an oxide alloy layer containing Si and Zr. According to the present invention, an antireflection film having excellent alkali resistance can be obtained while ensuring an excellent antireflection function.

Further, in the present invention, Si and Z in the oxide alloy containing Si and Zr forming the antireflection layer.
The content rate of Zr with respect to the total amount with r is specified. This makes it possible to obtain an antireflection film having high alkali resistance while ensuring an excellent antireflection function.

In the antireflection film of the present invention, Si, SiO _x (where x = 1 to 2), SiN, SiO _x N _y (where x =) are preferably provided between the substrate and the antireflection layer. 1
˜2, y = 0.2 to 0.6), CrO _x (where x =
0.2 to 1.5) and ZrO _x (where x = 1 to 2)
The adhesive layer is made of at least one material selected from the above. Thereby, the adhesion between the substrate and the antireflection layer is improved, and the mechanical strength of the antireflection film is improved.

Further, in the present invention, an antifouling layer preferably made of an alkoxysilane compound having a perfluoropolyether group is provided on the antireflection layer. As a result, the dustproof and antistatic effects of the antireflection film can be obtained.
An improvement in mechanical strength can be obtained.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic sectional view of the antireflection film of the present invention. The antireflection film includes a first high refractive index layer 5, a first low refractive index layer 7, and a second high refractive index layer 9 on a substrate 3 with an adhesive layer 4 for improving the adhesiveness interposed therebetween. , Second
The low-refractive index layer 11 and the third low-refractive index layer 13 are sequentially laminated to form an antireflection layer 20, and the antifouling layer 13 is formed on the antireflection layer 20. There is.

Here, in each layer constituting the antireflection layer 20, the first and second high refractive index layers 5 and 9 are the first to the first layers.
It is assumed that it is made of a material having a higher refractive index than the third low refractive index layers 7, 11, and 13.

The substrate 3 constituting the above antireflection film has high transparency in the visible light region such as alicyclic polyolefin resin such as PET (polyethylene terephthalate) and PC (polycarbonate) and TAC (triacetylene cellulose). A film can be applied. However, the substrate 3 is not limited to an organic substance, and may be an inorganic substance. Further, the substrate 3 may have a structure in which the hard coat layer 2 is formed on the highly transparent film 1 as shown in FIG.

The adhesion layer 4 is made of Si, SiO _x (where x =
1-2), SiN, SiO _x N _y (where x = 1 to 2, y
= 0.2 to 0.6), CrO _x (however, x = 0.2 to
1.5) and ZrO _x (where x = 1 to 2), TiO _x
(However, x = 1 to 2) at least one kind of material selected is applied, and the film can be formed by, for example, a DC sputtering method. This adhesion layer 4
Is formed to a film thickness of about 3 to 5 nm to the extent that it does not affect the optical characteristics of the antireflection film.

Each layer constituting the antireflection layer 20 is sequentially formed by a sputtering method. The first high refractive index layer 5 and the second high refractive index layer 9 are made of TiO ₂ , Nb ₂ O ₅ and Si.
N, Ta ₂ O ₅ , ITO (Indium oxide doped with Ti), IZO (Indium oxide doped with Zr), G
ZO (Zr-doped germanium oxide), AZO
A material such as (Zr-doped aluminum oxide) can be applied to form a film by, for example, an AC reactive sputtering method.

The first low-refractive index layer 7 and the second low-refractive index layer 11 are made of a material such as SiO ₂ or MgF _{2 and} can be formed by, for example, an AC reactive sputtering method.

Antireflection layer 2 of the antireflection film of the present invention
Of the layers constituting 0, the layer formed at the position farthest from the substrate 3, that is, the third low refractive index layer 1 in FIG.
3 is formed by applying an alloy oxide of Si and Zr (Si-Zr-O).

Here, since the refractive index of the alloy oxide of Si and Zr changes depending on the component composition ratio, the component ratio is adjusted to optimize the refractive index. FIG. 2 shows the relationship between the component ratio of the alloy oxide of Si and Zr and the refractive index for light having a wavelength of 550 [nm]. The horizontal axis represents the Zr content [atomic%] with respect to the total amount of Si and Zr in the alloy, and the vertical axis represents the refractive index. The oxygen content in the Si-Zr-O film corresponds to the stoichiometric composition of each metal oxide.

As shown in FIG. 2, the refractive index increases as the Zr content increases. In the antireflection layer 20 constituting the antireflection film, the refractive index of the Si-Zr-O film, which is the low refractive index layer formed at the position farthest from the substrate 3, is applied to the antireflection film having the conventional structure. 1.52 or less, preferably 1.58 or less, in order to achieve the antireflection function by reducing so as to be practically comparable to the case of using SiO ₂ (refractive index = 1.48) as a known material. Select less than 1.52. Therefore, from Fig. 2, Si
The content of Zr with respect to the total amount of Si and Zr in the -Zr-O film needs to be 20 [atomic%] or less.

In order to improve the alkali resistance of the antireflection film, the third low refractive index layer 13, namely S
Zr with respect to the total amount of Si and Zr in the i-Zr-O film
Content of 5 [atomic%] or more, preferably 10 to 15
It is necessary to set [atomic%].

An antifouling layer 15 is formed on the third low refractive index layer 13. The antifouling layer 15 is formed by a wet method using, for example, an alkoxysilane compound having a perfluoropolyether group. The antifouling layer 15 is formed as a sufficiently thin layer so as not to affect practically the optical characteristics of the antireflection film.

With the above structure, an antireflection film having excellent antireflection performance, alkali resistance and antifouling property can be easily produced.

[0025]

EXAMPLES The antireflection film of the present invention will be described in detail below with reference to specific examples. Here, an example of design completion based on the measured optical constants of the optical material is shown, and the optimum design result may change if the optical constants change. The present invention is not limited to the examples, and can be arbitrarily modified within a range not impairing the gist of the present invention.

Example 1 In the antireflection film shown in FIG. 1, a TAC having a thickness of about 80 [μm] was used as the substrate 3.
A film 1 having (triacetylene cellulose: refractive index n = 1.50) on which a hard coat 2 having a thickness of about 5 [μm] is formed is used. On the substrate 3, SiO _x (x =
The adhesion layer 4 composed of 1-2) was formed into a film having a thickness of about 3 [nm] by the DC sputtering method. The first high refractive index layer 5 is formed on the adhesion layer 4 with Nb ₂ O ₅ having a film thickness of about 13 [nm].
As the first low refractive index layer 7, a SiO ₂ film having a thickness of about 36 [nm] was sequentially formed by AC reactive sputtering method. On the first low refractive index layer 7, a Nb ₂ O ₅ film having a film thickness of about 120 [nm] is formed as the second high refractive index layer 9, and a film thickness of about 60 [is formed as the second low refractive index layer 11. nm] of SiO
_{The two} films were sequentially formed by the AC reactive sputtering method. An alloy oxide layer of Si and Zr having a film thickness of about 30 [nm] was formed as a third low refractive index layer 13 on the second low refractive index layer 11 by an AC reactive sputtering method. The metal composition ratio of the alloy is Si (90 atom%) Zr (10
Atomic%) O, and the refractive index based on this composition ratio was about 1.5.

Next, an antifouling layer 15 having a thickness of about 3 to 5 nm is formed on the third low refractive index layer 13 by a wet method using an alkoxysilane compound having a perfluoropolyether group, and finally. The objective antireflection film was prepared. The structure of the antireflection film in [Example 1] described above is schematically shown below. TAC (80 μm) / hard coat (5 μm) / SiO
x (3 nm) / Nb ₂ O ₅ (13 nm) / SiO ₂ (36
nm) / Nb ₂ O ₅ (120 nm) / SiO ₂ (60n
m) / Si ₉₀ Zr ₁₀ O (30 nm) / antifouling layer (3 to
5 nm)

When the reflectance characteristics of the antireflection film of the present invention produced as described above were examined, the results shown in FIG. 3 were obtained. As shown in FIG. 3, the antireflection film of the present invention was designed to have a reduced reflectance with respect to light having a wavelength in the visible region, and exhibited good antireflection properties.

Next, an alkali resistance test was conducted on the antireflection film of the present invention produced as described above. In the alkali resistance test, the reflectance [%] of the antireflection film before and after the immersion of the antireflection film in 5 [min] of 1 [normal] sodium hydroxide aqueous solution was measured. Figure 4
The measurement results are shown in. In FIG. 4, the reflectance before the alkali resistance test is shown by a solid line, and the reflectance after the alkali resistance test is shown by a broken line. As shown in FIG. 4, the antireflection film of the present invention shows a good antireflection property, both before and after the alkali resistance test, because the reflectance for light having a wavelength in the visible region is reduced. I understood it.

[Comparative Example] Next, as a [Comparative Example], a conventional structure will be described.
The anti-reflection film was manufactured. In this example,
Antireflection film produced in the above [Example 1]
Of the third low refractive index layer 13 of SiZrO alloy
Not formed on the second high refractive index layer 9 ₂Consisting of
The low refractive index layer 11 of No. 2 was formed to a film thickness of about 90 (nm).
The structure of the anti-reflection film of [Comparative Example] is schematically shown below.
Show. TAC (80 μm) / hard coat (5 μm) / SiO
x (3nm) / Nb₂O_Five(13 nm) / SiO₂(36
nm) / Nb₂O_Five(120 nm) / SiO₂(90n
m) / antifouling layer (3-5 nm).

An alkali resistance test was carried out on the antireflection film of [Comparative Example] produced as described above. The reflectance was measured in the same manner as the test method performed in the above [Example 1]. The measurement result is shown in FIG. In FIG. 5, the reflectance before the alkali resistance test is shown by a solid line, and the reflectance after the alkali resistance test is shown by a broken line. As shown in FIG. 5, in the conventional antireflection film, the reflectance for light having a wavelength in the visible region is increased after the test as compared with before the alkali resistance test, and the antireflection property is deteriorated. all right.

Example 2 Next, a second application example of the antireflection film of the present invention will be described with reference to the schematic sectional view of FIG. TA having a thickness of about 80 [μm] as the base body 3
C (triacetylene cellulose: refractive index n = 1.50)
The hard coat 2 having a film thickness of about 5 [μm] formed on the film 1 was used. On the substrate 3, SiO _x (x =
The adhesion layer 4 composed of 1-2) was formed into a film having a thickness of about 3 [nm] by the DC sputtering method.

Next, as the high refractive index layer, a conductive layer 25 having a thickness of about 18 [nm] was formed of ITO as a high refractive index layer in place of the Nb ₂ O ₅ film of [Example 1]. By forming a layer having conductivity in this manner, an antistatic effect can be imparted to the finally obtained antireflection film.

On the conductive layer 25, a SiO ₂ film having a film thickness of about 36 [nm] was sequentially formed as the first low refractive index layer 7 by the AC reactive sputtering method. Next, a Nb ₂ O ₅ film having a film thickness of about 120 [nm] is formed as the second high refractive index layer 9,
As the second low refractive index layer 11, Si having a film thickness of about 60 [nm] is used.
O ₂ films were sequentially formed by the AC reactive sputtering method. On the second low refractive index layer 11, an alloy oxide layer of Si and Zr was formed as the third low refractive index layer 13 by the AC reactive sputtering method. The metal composition ratio of the alloy was Si (90 atomic%) Zr (10 atomic%) O and the refractive index was about 1.5.

Next, on the third low refractive index layer 13, a perf
Alkoxysilane compound having luoropolyether group
By using a wet method to form an antifouling layer 15 having a thickness of about 3 to 5 nm.
Form and finally produce the desired antireflection film
did. Antireflection film in [Example 2] described above
The structure of is schematically shown below. TAC (80 μm) / hard coat (5 μm) / ITO
(13 nm) / SiO ₂(36 nm) / Nb₂O_Five(12
0 nm) / SiO₂(60 nm) / Si₉₀Zr ₁₀O
(30 nm) / antifouling layer (3-5 nm)

When the reflectance characteristics of the antireflection film of the present invention produced as described above were examined, the results shown in FIG. 7 were obtained. As shown in FIG. 7, the antireflection film of [Example 2] of the present invention was designed to have a reduced reflectance with respect to light having a wavelength in the visible region, and exhibited good antireflection properties.

It should be noted that, compared with the Nb ₂ O ₅ film, ITO has a higher absorptivity with respect to light in the short wavelength region, and thus has a drawback that the transmissivity is deteriorated, but 10000 [Ω / □]
In order to impart a degree of conductivity, the film thickness is set to about 10-20.
Since it may be about [nm], the decrease in the transmittance for light in the visible region does not pose a practical problem. The conductive layer 2
In addition to ITO, 5 includes GZO (Ge-Zr-O),
IZO (In-Zr-O), AZO (Al-Zr-O)
Etc. can be used. The antireflection film formed with the conductive layer 25 having such a static electricity removing effect can reduce the generation of static electricity in the step of attaching the antireflection film to the display.
In particular, it is suitable for LCD (liquid crystal display element) and organic EL display applications.

[0038]

As described above, according to the invention of claim 1, an antireflection film having an antireflection layer in which at least three layers having different refractive indexes are alternately laminated on a substrate. Concerning the above, regarding the layer constituting the antireflection layer, the layer farthest from the substrate is specified as the layer formed of the oxide alloy layer containing Si and Zr, and thus the excellent antireflection function is obtained. It was possible to obtain an antireflection film excellent in alkali resistance while ensuring the above.

According to the second aspect of the invention, the content of Zr relative to the total content of Si and Zr in the oxide alloy containing Si and Zr forming the antireflection layer is specified. , An anti-reflection film having an excellent anti-reflection function and high alkali resistance can be obtained while improving the alkali resistance while reducing the refractive index of the oxide alloy layer containing Si and Zr. Was given.

According to the fourth aspect of the present invention, since the adhesion layer is provided between the base and the antireflection layer, the adhesion between the base and the antireflection layer is improved. As a result, the mechanical strength and durability of the antireflection film were improved.

According to the invention of claim 5, by providing an antifouling layer made of an alkoxysilane compound having a perfluoropolyether group on the surface, an antireflection film having excellent antifouling property can be obtained. .

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of an antireflection film of the present invention.

FIG. 2 is a diagram showing a change in refractive index depending on the Zr content with respect to the total amount of Si and Zr in a Si—Zr—O film.

FIG. 3 is a diagram showing reflectance characteristics of Example 1.

FIG. 4 is a diagram showing reflectance characteristics before and after an alkali resistance test of Example 1.

FIG. 5 is a diagram showing reflectance characteristics of a conventional antireflection film before and after an alkali resistance test.

FIG. 6 is a schematic sectional view showing a form of another example of the antireflection film of the present invention.

FIG. 7 is a diagram showing reflectance characteristics of Example 2;

[Explanation of symbols]

1 ... Film, 2 ... Hard coat, 3 ... Substrate, 4
...... Adhesion layer, 5 ...... First high refractive index layer, 7 ...... First low refractive index layer, 9 ...... Second high refractive index layer, 11 ...... Second low refractive index layer, 13 ...... Third low refractive index layer, 15 ...... Anti-fouling layer, 20 ...... Anti-reflection layer, 25 ...... Conductive layer, 29 ...... High refractive index layer, 30 ...... Anti-reflection layer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/1335 G02B 1/10 Z F term (reference) 2H091 FA37X FB06 FC02 LA16 2K009 AA06 AA15 BB24 BB28 CC03 CC42 DD04 EE03 EE05 4F100 AA12E AA17D AA20D AA20E AA27D AA27E AH03E AH06E AJ06 AR00B AR00C AR00D AR00E AS00E AT00A BA05 BA10A BA10D BA10E EH66 GB41 JL07E JL11E JN06 JN18B JN18C JN18D JN18C JN18D

Claims (5)

[Claims] 1. An antireflection film having an antireflection layer formed by alternately laminating at least three layers having different refractive indexes on a substrate, wherein the substrate is one of the layers constituting the antireflection layer. An antireflection film, characterized in that the layer farthest from is formed of an oxide alloy layer containing Si and Zr. 2. The Zr content of the oxide alloy containing Si and Zr is 5 with respect to the total amount of Si and Zr.
[Atomic%] to 20 [Atomic%], The antireflection film according to claim 1. 3. The wavelength of the oxide alloy layer of 550 [n
The refractive index (n) with respect to the light of [m] is 1.58 or less, The antireflection film according to claim 1. 4. An S layer between the substrate and the antireflection layer.
i, SiO _x (where x = 1 to 2), SiN, SiO _x N
_y (however, x = 1 to 2, y = 0.2 to 0.6), CrO _x
(However, x = 0.2 to 1.5) and ZrO _x (however,
The antireflection film according to claim 1, further comprising an adhesion layer made of at least one material selected from x = 1 to 2). 5. The antireflection film according to claim 1, wherein an antifouling layer made of an alkoxysilane compound having a perfluoropolyether group is provided on the antireflection layer.