TW202031485A - Antireflection film - Google Patents

Abstract

To provide an antireflection film having excellent reflection characteristics (low reflectivity) in a broad band, with suppressed coloring. An antireflection film comprises a transparent base material, and an adhesive layer, a first Nb2O5 layer, a first SiO2 layer, a second Nb2O5 layer, a second SiO2 layer, and an antifouling layer in this order from the transparent base material. The first Nb2O5 layer has an optical film thickness of 28 nm to 33 nm, the first SiO2 layer has an optical film thickness of 43 nm to 57 nm, the second Nb2O5 layer has an optical layer thickness of 264 nm to 288 nm, and the second SiO2 layer has an optical film thickness of 113 nm to 129 nm.

Description

Anti-reflective film

The present invention relates to an anti-reflection film.

Since the past, in order to prevent external light from reflecting into the display screens of CRT (Cathode Ray Tube), liquid crystal display devices, plasma display panels, etc., anti-reflection films arranged on the surface of the display screen have been widely used. As the antireflection film, for example, a multilayer film having a plurality of layers with different refractive indexes is known. It is known that higher anti-reflection performance (lower reflectivity in a wide frequency band) can be obtained by using such a multilayer film. The anti-reflection performance of the anti-reflection film is generally evaluated by the visual reflectivity Y (%). The lower the visual reflectivity, the better the anti-reflection performance. However, there is a problem that if the visual reflectance is to be lowered, the reflected hue is easily colored. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 11-204065 [Patent Document 2] Japanese Patent No. 5249054

[The problem to be solved by the invention]

The present invention was completed in order to solve the aforementioned problems, and its object is to provide an anti-reflection film with excellent reflection characteristics (low reflectivity) in a wide frequency band and suppressed coloration. [Technical means to solve the problem]

The anti-reflection film of the present invention has in order: a transparent substrate, an adhesion layer in order from the transparent substrate, a first Nb ₂ O ₅ layer, a first SiO ₂ layer, and a second and second Nb ₂ O ₅ layer , The second SiO ₂ layer and the antifouling layer, and the optical film thickness of the first Nb ₂ O ₅ layer is 28 nm ~ 33 nm, the optical film thickness of the first SiO ₂ layer is 43 nm ~ 57 nm, and the second Nb ₂ The optical film thickness of the O ₅ layer is 264 nm ~ 288 nm, and the optical film thickness of the second SiO ₂ layer is 113 nm ~ 129 nm. In one embodiment, the refractive index of the antifouling layer is 1.00 to 1.50. In one embodiment, the thickness of the antifouling layer is 3 nm-15 nm. In one embodiment, the maximum reflectance of the anti-reflection film in the wavelength range of 420 nm to 660 nm is 0.5% or less. In one embodiment, the transparent substrate includes a hard coat layer. In one embodiment, the anti-reflection film further includes an optical film on the surface of the transparent base material on the opposite side to the adhesion layer. According to another aspect of the present invention, an image display device is provided. This image display device includes the anti-reflection film described above.

According to the present invention, by appropriately adjusting the optical film thickness of a plurality of Nb ₂ O ₅ layers and SiO ₂ layers arranged, it is possible to provide an anti-reflection with excellent reflection characteristics (low reflectivity) in a wide band and suppressed coloration. membrane.

A. Overview of anti-reflection film FIG. 1 is a schematic cross-sectional view of an anti-reflection film according to an embodiment of the present invention. The anti-reflective film 100 sequentially has: a transparent substrate 10, an adhesion layer 20 in order from the transparent substrate 10, a first Nb ₂ O ₅ layer 30, a first SiO ₂ layer 40, and a second Nb ₂ O ₅ layer 50. The second SiO ₂ layer 60 and the anti-fouling layer 70. Furthermore, in Fig. 1, in order to facilitate the observation, the scale of thickness etc. in the drawing is different from the actual one.

In the present invention, the optical film thickness (refractive index×physical film thickness) of the first Nb ₂ O ₅ layer is 28 nm to 33 nm. In addition, the optical film thickness of the first SiO ₂ layer is 43 nm to 57 nm. In addition, the optical film thickness of the second Nb ₂ O ₅ layer is 264 nm to 288 nm. In addition, the optical film thickness of the second SiO ₂ layer is 113 nm to 129 nm.

In the present invention, by sequentially stacking the first Nb ₂ O ₅ layer 30, the first SiO ₂ layer 40, the second Nb ₂ O ₅ layer 50, and the second SiO ₂ layer 60, excellent reflection characteristics can be obtained. (Low reflectivity) anti-reflective film. Furthermore, by adjusting the optical film thickness of each layer to a specific range as described above, an anti-reflection film having a neutral reflection hue can be provided as an anti-reflection film having an anti-fouling layer. In addition, by adjusting the optical film thickness of each layer to a specific range, it is possible to produce an anti-reflection film that exhibits low reflectivity for both short-wavelength and long-wavelength incident light. One of the achievements of the present invention is to provide an anti-reflection film that can take into account both excellent reflection characteristics (low reflectivity) and neutral reflection hue in a wide frequency band as an anti-reflection film with an anti-fouling layer.

The maximum reflectance of the anti-reflection film in the wavelength range of 420 nm to 660 nm is 0.5% or less, preferably 0.4% or less, and more preferably 0.3% or less. The lower the "maximum reflectance in the wavelength range of 420 nm to 660 nm," the better, and the lower limit is, for example, 0.05% (preferably 0.03%). Furthermore, in this specification, the so-called reflectance means the visual reflectance Y. The measurement method will be described later.

Although not shown, the above-mentioned anti-reflection film may further include any appropriate other layers and films. For example, an optical film can be arrange|positioned on the surface on the opposite side of the adhesive layer of a transparent base material.

In one embodiment, an image display device provided with the above-mentioned anti-reflection film is provided. The image display device is not particularly limited, and examples thereof include CRTs, liquid crystal display devices, and plasma displays. In one embodiment, in the above-mentioned image display device, the anti-reflection film is provided on the outermost side of the visible side.

B. Transparent substrate The above-mentioned transparent substrate may be composed of any appropriate resin film as long as the effects of the present invention can be obtained. As specific examples of the resin constituting the resin film, polyolefin resins (for example, polyethylene, polypropylene), polyester resins (for example, polyethylene terephthalate, polyethylene naphthalate), and Amide resin (e.g. nylon-6, nylon-66), polystyrene resin, polyvinyl chloride resin, polyimide resin, polyvinyl alcohol resin, ethylene-vinyl alcohol resin, (meth)acrylic resin, (Meth)acrylonitrile resin, cellulosic resin (for example, triacetyl cellulose, diacetyl cellulose, celluloid). The transparent substrate may be a single layer or a laminate of multiple resin films, or a laminate of a resin film (single layer or laminate) and the hard coat layer described below. The transparent substrate (essentially a composition for forming the transparent substrate) may contain any appropriate additives. Specific examples of additives include antistatic agents, ultraviolet absorbers, plasticizers, lubricants, colorants, antioxidants, and flame retardants. Furthermore, the material constituting the transparent substrate is well known in the field, and therefore detailed description is omitted.

In one embodiment, the transparent substrate can function as a hard coat layer. That is, as described above, the transparent substrate may be a laminate of a resin film (single layer or laminate) and a hard coat layer described below, or the hard coat layer alone may constitute the transparent substrate. When the transparent substrate is composed of a laminate of a resin film and a hard coat layer, the hard coat layer may be arranged adjacent to the adhesion layer. In one embodiment, the hard coat layer is a hardened layer of any suitable ionizing radiation-curable resin. Examples of ionizing rays include ultraviolet rays, visible light, infrared rays, and electron beams. Ultraviolet rays are preferred, and therefore the ionizing radiation-curable resin is preferably an ultraviolet-curable resin. Examples of ultraviolet curable resins include (meth)acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, epoxy resins, and the like. For example, as a representative example of the (meth)acrylic resin, a cured product (polymer) obtained by curing a polyfunctional monomer containing a (meth)acryloxy group with ultraviolet rays can be cited. The polyfunctional monomer may be used alone or in combination of plural kinds. Any appropriate photopolymerization initiator can be added to the polyfunctional monomer. Furthermore, the material constituting the hard coat layer is well known in the art, and therefore detailed description is omitted.

Any appropriate inorganic or organic fine particles can be dispersed in the hard coat layer. The particle size of the fine particles is, for example, 0.01 μm to 3 μm. Alternatively, uneven shapes may be formed on the surface of the hard coat layer. By adopting such a structure, a light diffusive function generally called anti-glare can be imparted. As the fine particles dispersed in the hard coat layer, silicon oxide (SiO ₂ ) can be preferably used from the viewpoints of refractive index, stability, heat resistance, and the like. Furthermore, the hard coat layer (essentially a composition for forming the hard coat layer) may contain any appropriate additives. Specific examples of additives include leveling agents, fillers, dispersants, plasticizers, ultraviolet absorbers, surfactants, antioxidants, and thixotropic agents.

The hard coat layer has a hardness of preferably H or more, more preferably 3H or more in the pencil hardness test. The pencil hardness test can be measured based on JIS K 5400.

The thickness of the transparent substrate can be appropriately set according to the purpose, the structure of the transparent substrate, and the like. When the transparent substrate is configured in the form of a single layer or a laminate of a resin film, the thickness is, for example, 10 μm to 200 μm. When the transparent substrate includes a hard coat layer or when it is composed of a hard coat layer alone, the thickness of the hard coat layer is, for example, 1 μm to 50 μm.

The light transmittance of the transparent substrate is preferably 60% to 99%, more preferably 80% to 99%.

The refractive index of the transparent substrate (when the transparent substrate has a laminated structure, the refractive index of the layer adjacent to the adhesion layer) is preferably 1.45 to 1.65, more preferably 1.50 to 1.60. Furthermore, in this specification, unless otherwise specified, the "refractive index" refers to the refractive index measured based on JIS K 7105 at a temperature of 25°C and a wavelength of λ=580 nm.

C. Adhesive layer The above-mentioned adhesive layer is a layer that can be provided in order to improve the adhesiveness between adjacent layers (for example, the transparent substrate and the first Nb ₂ O ₅ layer). The adhesion layer can be made of silicon, for example. The thickness of the adhesive layer is, for example, 2 nm to 5 nm.

In addition to being formed between the transparent substrate and the first Nb ₂ O ₅ layer, the adhesion layer can also be formed between the first Nb ₂ O ₅ layer and the first SiO ₂ layer, the first SiO ₂ layer and the second Nb ₂ O ₅ layer. Any position between the ₂ O ₅ layer and the second Nb ₂ O ₅ layer and the second SiO ₂ layer.

The adhesion layer is typically formed by a dry process. Specific examples of the dry process include PVD (Physical Vapor Deposition) method and CVD (Chemical Vapor Deposition) method. Examples of the PVD method include a vacuum vapor deposition method, a reactive vapor deposition method, an ion beam assist method, a sputtering method, and an ion plating method. As the CVD method, a plasma CVD method can be cited. In the case of in-line processing, the sputtering method can be preferably used.

D. First Nb ₂ O ₅ layer The above-mentioned first Nb ₂ O ₅ layer is composed of Nb ₂ O ₅ (refractive index: 2.34). In the present invention, regarding the first Nb ₂ O ₅ layer (and the following first SiO ₂ layer, second Nb ₂ O ₅ layer, and second SiO ₂ layer), by not only setting the refractive index to an appropriate value, Moreover, by specifying the material of the constituent layer, an anti-reflection film with a neutral reflection hue can be obtained.

The first Nb ₂ O ₅ layer (and the following first SiO ₂ layer, second Nb ₂ O ₅ layer, and second SiO ₂ layer) can be formed by a so-called dry process. Specific examples of the dry process include PVD (Physical Vapor Deposition) method and CVD (Chemical Vapor Deposition) method. Examples of the PVD method include a vacuum vapor deposition method, a reactive vapor deposition method, an ion beam assist method, a sputtering method, and an ion plating method. As the CVD method, a plasma CVD method can be cited. In one embodiment, the sputtering method can be preferably used. If the sputtering method is used, the deviation of the reflected color tone can be reduced.

As mentioned above, the optical film thickness of the first Nb ₂ O ₅ layer is 28 nm to 33 nm. The optical film thickness of the first Nb ₂ O ₅ layer is preferably 28 nm to 32 nm, more preferably 28 nm to 30 nm. If it is in this range, an anti-reflection film with a neutral reflection hue can be obtained.

The ratio of the optical film thickness of the first SiO ₂ layer to the optical film thickness of the first Nb ₂ O ₅ layer is preferably 1.4-2.1, more preferably 1.7-2.1. If it is such a range, an anti-reflection film having excellent reflection characteristics and a neutral reflection hue can be obtained.

The thickness of the first Nb ₂ O ₅ layer is preferably 12.0 nm to 14.1 nm, more preferably 12.0 nm to 13.7 nm, and still more preferably 12.0 nm to 12.8 nm.

E. First SiO ₂ layer The above-mentioned first SiO ₂ layer is composed of SiO ₂ (refractive index: 1.46).

As mentioned above, the optical film thickness of the first SiO ₂ layer is 43 nm to 57 nm. If it is in this range, an anti-reflection film with a neutral reflection hue can be obtained.

The ratio of the optical film thickness of the second Nb ₂ O ₅ layer to the optical film thickness of the first SiO ₂ layer is preferably 4.7 to 6.7, and more preferably 5.1 to 6.1. If it is such a range, an anti-reflection film having excellent reflection characteristics and a neutral reflection hue can be obtained.

The thickness of the first SiO ₂ layer is preferably 29.5 nm to 39.0 nm.

F. Second Nb ₂ O ₅ layer The above-mentioned second Nb ₂ O ₅ layer is composed of Nb ₂ O ₅ (refractive index: 2.34).

As mentioned above, the optical film thickness of the second Nb ₂ O ₅ layer is 264 nm to 288 nm. If it is in this range, an anti-reflection film with a neutral reflection hue can be obtained.

The ratio of the optical film thickness of the second SiO ₂ layer to the optical film thickness of the second Nb ₂ O ₅ layer is preferably 0.40 to 0.48, and more preferably 0.43 to 0.44. If it is such a range, an anti-reflection film having excellent reflection characteristics and a neutral reflection hue can be obtained.

The thickness of the second Nb ₂ O ₅ layer is preferably 112.8 nm to 123.1 nm.

G. second SiO ₂ layer and the second layer is made of SiO ₂ SiO _2: configuration (refractive index 1.46).

As mentioned above, the optical film thickness of the second SiO ₂ layer is 113 nm to 129 nm. If it is in this range, an anti-reflection film with a neutral reflection hue can be obtained.

The thickness of the first SiO ₂ layer is preferably 77.4 nm to 88.4 nm.

H. Antifouling layer The antifouling layer provided as required is a layer that can impart water repellency, oil repellency, sweat resistance, and antifouling properties to the surface of the anti-reflective film. One of the characteristics of the present invention is to adjust the above-mentioned inorganic layers (first Nb ₂ O ₅ layer, first SiO ₂ layer, second Nb ₂ O ₅ layer, and second SiO ₂ layer) based on the existence of the antifouling layer.的optical film thickness.

The material constituting the antifouling layer is preferably a fluorine-containing compound. The fluorine-containing compound imparts antifouling properties and also contributes to lowering the refractive index. Among them, in terms of excellent water repellency and high antifouling properties, a fluorine-based polymer containing a perfluoropolyether skeleton is preferred. From the standpoint of improving antifouling properties, perfluoropolyethers having a backbone structure that can be rigidly arranged are particularly preferred. The structural unit of the main chain skeleton of the perfluoropolyether is preferably a perfluorooxyalkylene group which may have a branched chain with a carbon number of 1 to 4, for example, perfluorooxymethylene (-CF ₂ O-) , Perfluoroethylene oxide (-CF ₂ CF ₂ O-), Perfluoroethylene oxide (-CF ₂ CF ₂ CF ₂ O-), Perfluoroisopropyl oxide (-CF(CF ₃ )CF ₂ O-) and so on.

The refractive index of the antifouling layer is preferably 1.00 to 1.50, more preferably 1.10 to 1.50, and still more preferably 1.20 to 1.45. If it is in this range, the effect of setting the optical film thickness of the first Nb ₂ O ₅ layer, the first SiO ₂ layer, the second Nb ₂ O ₅ layer, and the second SiO ₂ layer within the above range becomes more remarkable. It is possible to provide an anti-reflection film with excellent reflection characteristics (low reflectivity) in a wide frequency band and suppressed coloration.

In one embodiment, the anti-reflection film of the present invention is formed in such a way that the difference between the refractive index of the antifouling layer and the refractive index of the second SiO ₂ layer is small. The difference between the refractive index of the antifouling layer and the refractive index of the second SiO ₂ layer (the refractive index of the second SiO ₂ layer-the refractive index of the antifouling layer) is preferably -0.1 to 0.3, more preferably -0.05 to 0.2, More preferably, it is 0 to 0.15.

The thickness of the antifouling layer is preferably 3 nm to 15 nm, more preferably 3 nm to 10 nm. If it is in such a range, an antifouling layer with less color unevenness and excellent antifouling performance can be formed. In addition, if the thickness of the antifouling layer is in the above range, the optical film thickness of the first Nb ₂ O ₅ layer, the first SiO ₂ layer, the second Nb ₂ O ₅ layer, and the second SiO ₂ layer is set to the above range The effect becomes more significant, and it is possible to provide an anti-reflection film with excellent reflection characteristics (low reflectivity) in a wide frequency band and suppressed coloration.

Regarding the method of forming the antifouling layer, physical vapor deposition methods such as vapor deposition and sputtering, chemical vapor deposition methods, reverse coating methods, die nozzle coating methods, gravure coating methods, and other wet methods can be used according to the forming materials. Coating method, etc.

I. Optical film As an optical film provided as needed, a polarizing plate, a retardation film, a brightness enhancement film, a diffusion film, a conductive film, etc. are mentioned. The optical film can be laminated on the transparent substrate via any suitable adhesive or adhesive. [Example]

Hereinafter, the present invention will be specifically explained through examples, but the present invention is not limited to these examples. The test and evaluation methods in the examples are as follows. In addition, unless otherwise specified, the "%" in the examples is the basis of weight.

再者，將藉由上述評價取得之反射率之光譜示於圖2。<Evaluation method> (1) Physical thickness The thickness of each layer was measured by TEM (transmission electron microscope) cross-sectional observation. (2) Refractive Index Using samples for evaluation corresponding to each layer, the refractive index of each layer was measured with a spectroscopic ellipsometer. (3) Optical film thickness The physical thickness and the refractive index are multiplied to calculate the optical film thickness. (4) Reflective characteristics E A light-shielding black acrylic plate was bonded to the transparent substrate side of the anti-reflection film via an adhesive to prepare a sample for evaluation. Then, using the spectrophotometer "U4100" manufactured by Hitachi, Ltd., under the condition of 5° regular reflection (wavelength: 380 nm ~ 780 nm), the anti-reflection surface's visual reflectance Y, reflection L, and reflection hue a ^* , The measurement of b ^* value of reflection hue. Use the following formula to calculate the E value. The E value is an index used to evaluate the hue, and the lower the E value, the closer the reflected hue is to neutral. [Number 1]

Furthermore, the reflectance spectrum obtained by the above evaluation is shown in FIG. 2.

[Example 1] (Production of transparent substrate) 100 parts by weight of acrylic urethane resin (manufactured by Dainippon Ink Chemical Industry Co., Ltd., trade name "UNIDIC V4025", refractive index 1.52) as inorganic particles 50 parts by weight of silica particles (manufactured by Nissan Chemical Industry Co., Ltd., trade name "MEK-ST-L", average particle size 50 nm) and 5 parts by weight of UV initiator "Irgacure184" manufactured by BASF company . Then, a mixed solution of MEK and PGM as a dilution solvent was added to the above solution, and the solvent ratio was adjusted so that MEK/PGM=40/60, to obtain a composition for forming a hard coat layer. The composition for forming a hard coat layer was applied to one side of a resin film (TAC: manufactured by Fujifilm Corporation, trade name "TD80UL") so that the thickness after drying was 5 μm, and dried at 80° C. for 2 minutes. Thereafter, a high-pressure mercury lamp was used to irradiate ultraviolet rays with a cumulative light intensity of 300 mJ/cm ^{2 to} harden the coating layer to form a hard coat layer on the resin film. (Formation of Inorganic Layer) The Si sputtering target was set in a magnetron sputtering device, and an adhesion layer (thickness 5 nm) composed of an SiOx layer was formed on the hard coat layer. Then, the Nb target was set in a magnetron sputtering device, and reactive sputtering was performed to form a first Nb ₂ O ₅ layer (thickness 12 nm, refractive index 2.34) on the adhesion layer. Then, the Si target was set in a magnetron sputtering device, and reactive sputtering was performed to form a first SiO ₂ layer (thickness 39 nm, refractive index 1.46) on the first Nb ₂ O ₅ layer. Then, on the first SiO ₂ layer, is formed by the same method as the first layer of Nb ₂ O ₅ second method of forming the Nb ₂ O ₅ layer (thickness 119 nm, a refractive index of 2.34). Further, on the second layer of Nb ₂ O _5, is formed by the same method as the first method of forming the SiO ₂ layer of the second SiO ₂ layer (thickness: 78 nm, refractive index 1.46). (Formation of antifouling layer) On the second SiO ₂ layer, a fluorine-based resin (contained in the main chain skeleton containing -(CF ₂ -CF ₂ -O)-(CF ₂ -CF ₂ -O)-and -(CF _2- -O)- perfluoroether (fluorine resin) solution to form an antifouling layer with a thickness of 9 nm and a refractive index of 1.32. In this way, a transparent substrate (resin film/hard coat layer)/adhesive layer (SiOx layer)/first Nb ₂ O ₅ layer/first SiO ₂ layer/second Nb ₂ O ₅ layer/second SiO _{2 is obtained.} Layer/anti-fouling layer). The obtained antireflection film was used for the above evaluation. The results are shown in Table 1.

[Examples 2 to 6, Comparative Examples 1 to 6] The thicknesses of the first Nb ₂ O ₅ layer, the first SiO ₂ layer, the second Nb ₂ O ₅ layer, the second SiO ₂ layer, and the antifouling layer were taken as the table Except for the thickness shown in 1, an anti-reflection film was obtained in the same manner as in Example 1. The obtained antireflection film was used for the above evaluation. The results are shown in Table 1.

[Comparative Example 7] In the same manner as in Example 1, a transparent substrate was produced. Then, ZrO _{2 was} set in a vacuum evaporation apparatus, and vacuum evaporation was performed to form a first ZrO ₂ layer (thickness 13 nm, refractive index 2.22) on the transparent substrate. Then, MgF _{2 was} set in a vacuum evaporation device, and vacuum evaporation was performed to form a first MgF ₂ layer (thickness 34 nm, refractive index 1.38) on the first ZrO ₂ layer. Then, on said first layer of MgF _2, is formed by the same method as the first method of forming the ZrO ₂ layer a second ZrO ₂ layer (thickness 118 nm, a refractive index of 2.22). Further, on the second layer of ZrO _2, by the same method of forming the first layer of MgF ₂ of the method for forming the second layer of MgF ₂ (thickness of 91 nm, refractive index 1.38). On the second MgF ₂ layer, a fluorine-based resin (contained in the main chain skeleton containing -(CF ₂ -CF ₂ -O)- and -(CF ₂ -O)-perfluoro resin) was coated by gravure coating method Fluorine-based resin) solution of ether to form an antifouling layer with a thickness of 5 nm and a refractive index of 1.32. In this way, a transparent substrate (resin film/hard coat layer)/adhesive layer (SiOx layer)/first ZrO ₂ layer/first MgF ₂ layer/second ZrO ₂ layer/second MgF ₂ layer/antifouling Layer) of the anti-reflective film. The obtained antireflection film was used for the above evaluation. The results are shown in Table 1.

[Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative example 5 Comparative example 6 Physical thickness (nm) Antifouling layer (n: 1.32) 9 9 9 9 3 5 9 9 9 9 9 5 Second SiO ₂ layer (n: 1.46) 78 81 84 84 88 86 77 79 97 84 84 84 Second Nb ₂ O ₅ layer (n: 2.34) 119 113 118 123 118 118 105 112 35 122 120 120 The first SiO ₂ layer (n: 1.46) 39 30 36 39 36 36 25 28 40 30 43 43 The first Nb ₂ O ₅ layer (n: 2.34) 12 12 12 14 12 12 15 12 twenty two 12 12 12 Optical film thickness (nm) Second SiO ₂ layer (n: 1.46) 113.9 118.3 122.6 122.6 128.5 125.6 112.4 115.3 141.6 122.6 122.6 122.6 Second Nb ₂ O ₅ layer (n: 2.34) 278.5 264.4 276.1 287.8 276.1 276.1 245.7 262.1 81.9 285.5 280.8 280.8 The first SiO ₂ layer (n: 1.46) 56.9 43.8 52.6 56.9 52.6 52.6 36.5 40.9 58.4 43.8 62.8 62.8 The first Nb ₂ O ₅ layer (n: 2.34) 28.1 28.1 28.1 32.8 28.1 28.1 35.1 28.1 51.5 28.1 28.1 28.1 characteristic Reflectivity Y 0.29% 0.20% 0.15% 0.15% 0.16% 0.16% 0.34% 0.31% 0.25% 0.43% 0.20% 0.27% Reflection L 0.5 -1.3 -2.7 -2.8 -2.4 -2.3 1.5 1.0 -0.2 2.9 -1.4 0.1 Reflection hue a* -0.9 -0.3 -2.0 0.8 -2.2 -2.3 4.3 -4.0 2.4 5.8 -8.0 -7.4 Reflection hue b* 0.0 1.9 0.1 -2.5 0.0 1.5 -1.1 8.0 -7.4 0.3 0.7 -5.1 E 1.1 2.3 3.3 3.9 3.3 3.6 4.7 9.0 7.7 6.5 8.2 9.0 Comparative example 7 Physical thickness (nm) Antifouling layer (n: 1.32) 5 MgF ₂ layers (n: 1.38) 91 ZrO ₂ layers (n: 2.22) 118 MgF ₂ layers (n: 1.38) 34 ZrO ₂ layers (n: 2.22) 13 Optical film thickness (nm) MgF ₂ layers (n: 1.38) 125.6 ZrO ₂ layers (n: 2.22) 262.0 MgF ₂ layers (n: 1.38) 46.9 ZrO ₂ layers (n: 2.22) 28.9 characteristic Reflectance Y(%) 0.24% Reflection L -0.4 Reflection hue a* 2.2 Reflection hue b* -6.7 E 7.1

It can be seen from Table 1 that the anti-reflective film of the present invention is provided with a plurality of layers composed of specific inorganic substances and the optical film thickness of each layer is controlled to a specific value, and has low reflection characteristics and a neutral reflection hue. Furthermore, it can be seen from FIG. 2 that the anti-reflection film of the present invention has excellent reflection characteristics in a wide frequency band (specifically, the maximum reflectance in the wavelength range of 420 nm to 660 nm is 1.5% or less). [Industrial availability]

The anti-reflection film of the present invention can be preferably used to prevent external light from being reflected in image display devices such as CRTs, liquid crystal display devices, and plasma display panels.

10: Transparent substrate 20: Adhesive layer 30: First Nb ₂ O ₅ layer 40: First SiO ₂ layer 50: Second Nb ₂ O ₅ layer 60: Second SiO ₂ layer 70: Antifouling layer 100: Anti-reflection membrane

Fig. 1 is a schematic cross-sectional view of an anti-reflection film according to an embodiment of the present invention. Figure 2 shows the reflectance spectra of the anti-reflection films obtained in Examples and Comparative Examples.

10: Transparent substrate

20: Tight layer

30: The first Nb ₂ O ₅ layer

40: The first SiO ₂ layer

50: The second Nb ₂ O ₅ layer

60: Second SiO ₂ layer

70: Antifouling layer

100: Anti-reflective film

Claims (7)

An anti-reflective film, which sequentially has: a transparent substrate, an adhesive layer in order from the transparent substrate, a first Nb ₂ O ₅ layer, a first SiO ₂ layer, and a second and second Nb ₂ O ₅ layer , The second SiO ₂ layer and the antifouling layer, and the optical film thickness of the first Nb ₂ O ₅ layer is 28 nm ~ 33 nm, the optical film thickness of the first SiO ₂ layer is 43 nm ~ 57 nm, and the second Nb ₂ The optical film thickness of the O ₅ layer is 264 nm to 288 nm, and the optical film thickness of the second SiO ₂ layer is 113 nm to 129 nm. The anti-reflection film of claim 1, wherein the refractive index of the anti-fouling layer is 1.00 to 1.50. The anti-reflection film of claim 1 or 2, wherein the thickness of the anti-fouling layer is 3 nm to 15 nm. Such as the anti-reflective film of claim 1 or 2, the maximum reflectance in the wavelength range of 420 nm to 660 nm is 0.5% or less. The anti-reflection film of claim 1 or 2, wherein the transparent substrate includes a hard coat layer. The anti-reflection film of claim 1 or 2, wherein an optical film is further provided on the surface of the transparent substrate on the opposite side to the adhesion layer. An image display device provided with the anti-reflection film as claimed in claim 1.

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