KR20200084862A - Hard coat film, optical laminate and image display device - Google Patents

Abstract

The hard coat film 1 includes a hard coat layer 11 on one main surface of the film base 10. The hard coat layer contains a binder resin and an inorganic filler, and the content of the inorganic filler relative to 100 parts by weight of the binder resin is 20 to 80 parts by weight. The average primary particle size of the filler is preferably 25 to 70 nm. The arithmetic average roughness of the surface of the hard coat layer is preferably 2 nm or more. As for b ^* of diffuse reflection light of a hard-coat layer, -0.2 or more is preferable.

Description

Hard coat film, optical laminate and image display device

The present invention relates to a hard coat film and an optical laminate in which an inorganic thin film is formed on a hard coat film.

A film disposed on the viewer-side surface of an image display device such as a liquid crystal display or an organic EL display, or a film used by bonding to a glass window, is used for the purpose of preventing scratches due to contact from the outside, etc. A coat layer may be formed. Various functions can be provided by forming the inorganic thin film on the hard coat layer. For example, an antireflection film is obtained by forming an antireflection layer made of a plurality of thin films having different refractive indices on a hard coat layer of a hard coat film.

In the optical laminate having the inorganic thin film layer on the hard coat layer, the adhesion between the hard coat layer and the inorganic layer is small, and interlayer peeling may occur between the hard coat layer and the inorganic layer. In particular, in an environment exposed to ultraviolet rays, such as outdoors, the problem of interlayer peeling tends to become remarkable. Patent Document 1 discloses that by adding a filler in the hard coat layer, the surface shape of the hard coat layer can be adjusted to improve the adhesion between the hard coat layer and the inorganic layer.

Japanese Patent Application Publication No. 2017-161893

As described in Patent Document 1, the adhesion between the hard coat layer and the inorganic thin film is improved by including the inorganic filler in the hard coat layer. However, the film containing the filler in the hard coat layer may be viewed as the reflected light is bluish-colored. Particularly, in the antireflection film in which the antireflection layer is formed on the hard coat layer, since the amount of reflected light is small, there is a problem that the color of the reflected light is easily perceived.

The present invention relates to a hard coat film having a hard coat layer on one main surface of a film substrate and an optical laminate comprising an inorganic thin film on a hard coat layer of a hard coat film. An example of the optical laminate is an antireflection film comprising an antireflection layer made of a plurality of inorganic thin films having different refractive indices on a hard coat layer. Such an optical laminated body is arranged on the viewing side surface of an image display device, for example.

The hard coat layer contains a binder resin and an inorganic filler, and the content of the inorganic filler relative to 100 parts by weight of the binder resin is 20 to 80 parts by weight. The average primary particle size of the filler is 25 to 70 nm. The arithmetic average roughness of the surface of the hard coat layer is 2 nm or more. The thickness of the hard coat layer is preferably about 1 to 10 μm.

As for b ^* of the reflected light calculated|required from the diffusion spectrum of the surface of a hard-coat layer, -0.2 or more is preferable. The Y value of the diffuse reflected light is preferably 0.09% or less, and the diffuse reflectance at a wavelength of 380 nm is preferably 0.05% or less.

The absolute value of the difference between the refractive index at a wavelength of 405 nm of the binder resin constituting the hard coat layer and the refractive index at a wavelength of 405 nm of the inorganic filler is preferably 0.09 or less. The smaller the refractive index difference between the binder resin and the inorganic filler, and the smaller the particle diameter of the inorganic filler, the larger the b ^* of the diffuse reflection light on the surface of the hard coat layer tends to be, and the coloring of the reflected light tends to be reduced.

The optical laminate of the present invention includes an inorganic thin film formed in contact with the hard coat layer of the hard coat film. In the antireflection film, an inorganic thin film having a different refractive index is formed as an inorganic thin film (antireflection layer).

The inorganic thin film in contact with the hard coat layer may be an inorganic oxide having a non-stoichiometric composition. The inorganic thin film in contact with the hard coat layer may be a silicon oxide thin film. For example, when the silicon oxide thin film having a non-stoichiometric composition is formed in contact with the hard coat layer, the adhesion between the hard coat film and the inorganic thin film tends to be improved. An additional layer such as an antifouling layer may be formed on the inorganic thin film.

In the hard coat film and the optical laminate of the present invention, since the hard coat layer contains a binder resin and an inorganic filler, adhesion between the hard coat layer and the inorganic thin film is excellent. Further, since the diffuse reflection b ^* of the hard coat layer is within a predetermined range, coloring of the reflected light is small, and visibility of an image display device or the like can be improved.

1 is a cross-sectional view showing a lamination form of a hard coat film.
2 is a cross-sectional view showing a laminated form of an antireflection film.

1 is a cross-sectional view showing an example of a laminated structure of a hard coat film of the present invention. The hard coat film 1 includes a hard coat layer 11 on one main surface of the film base 10. The optical laminate of the present invention is provided with an inorganic thin film in contact with the hard coat layer 11 of the hard coat film 1. Examples of the optical laminate include films for image display devices such as anti-reflection films and transparent electrode films, solar radiation adjusting films, heat-insulating and insulating films, dimming films, and electromagnetic shielding films, films formed on glass windows, show windows, etc., and gas barriers. And films.

2 is a cross-sectional view showing an example of a laminated structure of an antireflection film that is one embodiment of an optical laminate. The antireflection film 100 includes the antireflection layer 5 on the hard coat layer 11 of the hard coat film 1. The antireflection layer 5 is a laminate of two or more inorganic thin films having different refractive indices. In the antireflection film 100 shown in FIG. 2, the antireflection layer 5 is provided with a primer layer 50 on a surface in contact with the hard coat layer 11, and the high refractive index layers 51 and 53 thereon. The low refractive index layers 52 and 54 are alternately stacked.

Hereinafter, materials, properties, and the like of each layer will be described in order, according to preferred embodiments of the hard coat film shown in FIG. 1 and the antireflection film shown in FIG. 2.

[Hard coat film]

<film description>

As the film base 10 of the hard coat film 1, for example, a transparent film is used. The visible light transmittance of the transparent film is preferably 80% or more, and more preferably 90% or more. As the resin material constituting the transparent film, for example, a resin material excellent in transparency, mechanical strength, and thermal stability is preferable. Specific examples of the resin material include cellulose-based resins such as triacetyl cellulose, polyester-based resins, polyethersulfone-based resins, polysulfone-based resins, polycarbonate-based resins, polyamide-based resins, polyimide-based resins, and polyolefin-based resins. Resins, (meth)acrylic resins, cyclic polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof.

The film base 10 is not necessarily transparent. Moreover, you may use the laminated body of several films as a film base material 10. For example, as described later, a polarizing plate with a protective film formed on the surface of the polarizer may be used as the film substrate 10.

The thickness of the film base material is not particularly limited, but from the viewpoints of workability such as strength and handling properties, thin layer properties, etc., about 5 to 300 μm is preferable, 10 to 250 μm is more preferable, and 20 to 200 μm is further desirable.

<hard coat layer>

The hard coat film 1 is formed by forming the hard coat layer 11 on the main surface of the film base 10. The hard coat layer contains a binder resin and an inorganic filler. For example, a hard coat layer is formed by applying a composition for forming a hard coat layer comprising a binder resin component (curable resin component for forming a binder resin) and an inorganic filler on a film substrate and curing the binder resin component. do.

(Binder resin)

As the binder resin of the hard coat layer 11, curable resins such as thermosetting resins, photocurable resins and electron beam curable resins are preferably used. Examples of the curable resin include polyester, acrylic, urethane, acrylic urethane, amide, silicone, silicate, epoxy, melamine, oxetane, and acrylic urethane. Among these, acrylic resin, acrylic urethane resin, and epoxy resin are preferred from the viewpoint of high hardness and photocurability, and acrylic urethane resin is particularly preferred.

The refractive index of the binder resin is generally about 1.4 to 1.6. As described in detail later, it is preferable that the binder resin has a small refractive index difference with the inorganic filler. For example, when silica particles are used as the inorganic filler, the refractive index at a wavelength of 405 nm of the binder resin is preferably 1.40 to 1.57, more preferably 1.41 to 1.55, and even more preferably 1.42 to 1.54.

The photocurable binder resin component contains a polyfunctional compound having two or more photopolymerizable (preferably ultraviolet polymerizable) functional groups. The polyfunctional compound may be a monomer or an oligomer. As the photopolymerizable polyfunctional compound, a compound containing two or more (meth)acryloyl groups in one molecule is preferably used.

As a specific example of the polyfunctional compound which has 2 or more (meth)acryloyl groups in 1 molecule, tricyclodecane dimethanol diacrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate , Trimethylolpropane triacrylate, pentaerythritol tetra(meth)acrylate, dimethylolpropanetetraacrylate, dipentaerythritolhexa(meth)acrylate, 1,6-hexanediol(meth)acrylate, 1, 9-nonanediol diacrylate, 1,10-decanediol (meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, dipropylene glycol diacrylate, isocyanuric acid Tri(meth)acrylate, ethoxylated glycerin triacrylate, ethoxylated pentaerythritol tetraacrylate, and oligomers or prepolymers thereof. In addition, in this specification, "(meth)acrylic" means acrylic and/or methacrylic.

The polyfunctional compound having two or more (meth)acryloyl groups in one molecule may have a hydroxyl group. When a polyfunctional compound containing a hydroxyl group is used as the binder resin component, the adhesion between the transparent substrate and the hard coat layer tends to be improved. As a compound which has a hydroxyl group and 2 or more (meth)acryloyl groups in 1 molecule, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, etc. are mentioned.

The acrylic urethane resin is a polyfunctional compound and contains a monomer or oligomer of urethane (meth)acrylate. As for the number of (meth)acryloyl groups which a urethane (meth)acrylate has, 3 or more are preferable, 4-15 are more preferable, and 6-12 are still more preferable. The molecular weight of the urethane (meth)acrylate oligomer is, for example, 3000 or less, preferably 500 to 2500, and more preferably 800 to 2000. The urethane (meth)acrylate is obtained, for example, by reacting (meth)acrylic acid or (meth)acrylic acid ester with hydroxy (meth)acrylate obtained from a polyol with diisocyanate.

The content of the polyfunctional compound in the composition for forming a hard coat layer is preferably 50 parts by weight or more based on 100 parts by weight of the total of the binder resin components (monomers, oligomers, and prepolymers that form a binder resin by curing), and 60 More preferably, it is more than 70 parts by weight, and even more preferably more than 70 parts by weight. When the content of the polyfunctional monomer is within the above range, the hardness of the hard coat layer tends to increase.

The binder resin component may further contain a monofunctional monomer. The content of the monofunctional monomer is preferably 50 parts by weight or less, more preferably 40 parts by weight or less, and even more preferably 30 parts by weight or less with respect to 100 parts by weight of the binder resin component.

(Weapon filler)

When the hard coat layer 11 contains an inorganic filler, irregularities are formed on the surface, and adhesion to the inorganic thin film 5 formed on the hard coat layer 11 can be improved. Materials of the inorganic filler include silica, titanium oxide, aluminum oxide, zirconium oxide, titanium oxide, niobium oxide, zinc oxide, tin oxide, cerium oxide, magnesium oxide, calcium carbonate, calcium sulfate, barium sulfate, talc, and kaolin. Can be lifted. Among these, silica particles are preferable from the viewpoint of having a low refractive index and reducing the difference in refractive index from the binder resin. As the inorganic filler, a porous inorganic filler or a hollow inorganic filler may be used.

From the viewpoint of forming an uneven shape excellent in adhesion to the inorganic thin film 5 on the surface of the hard coat layer 11, the average primary particle size of the inorganic filler is preferably 25 to 70 nm, and 30 to 60 nm It is more preferable. Moreover, from the viewpoint of suppressing the coloring of reflected light on the surface of the hard coat layer, the average primary particle size of the inorganic filler is preferably 55 nm or less, more preferably 50 nm or less, and even more preferably 45 nm or less. The average primary particle diameter is a weight average particle diameter measured by the Coulter count method.

It is preferable that the inorganic filler has a uniform particle diameter. Particularly, from the viewpoint of suppressing the coloring of reflected light, it is preferable that the content of coarse particles is small. The inorganic filler preferably has a 90% particle diameter (D90) of 100 nm or less, more preferably 80 nm or less, and even more preferably 70 nm or less. From the viewpoint of preventing aggregation of the inorganic filler, the 10% particle diameter (D10) of the inorganic filler is preferably 5 nm or more, more preferably 10 nm or more, and even more preferably 15 nm or more. In the cumulative particle size distribution (based on weight) by the Coulter count method, the particle diameter that becomes 10% cumulative from the small particle diameter side is D10, and the particle diameter that becomes 90% cumulative from the small particle diameter side is D90. For example, when D90 is 100 nm or less, the amount of particles having a particle diameter of 100 nm or more is 10% or less by weight.

Although the shape of an inorganic filler is not specifically limited, It is preferable that the aspect ratio is (approximately) spherical shape of 1.5 or less. The aspect ratio of the inorganic filler is more preferably 1.2 or less, and even more preferably 1.1 or less. By using a spherical inorganic filler, it is easy to form a concavo-convex shape excellent in adhesion to the inorganic thin film on the surface of the hard coat layer.

The content of the inorganic filler is preferably 20 to 80 parts by weight based on 100 parts by weight of the binder resin. When the content of the inorganic filler is within the above range, the dispersibility of the filler in the binder resin is excellent, and an uneven shape in which the convex portions are uniformly distributed in the surface is liable to be formed. In particular, in order to increase the arithmetic average roughness Ra of the hard coat layer and increase the adhesion between the hard coat layer and the inorganic thin film, the content of the inorganic filler relative to 100 parts by weight of the binder resin is preferably 30 to 75 parts by weight, and 35 to 70 The weight part is more preferable, and 40-65 weight part is more preferable.

(Formation of hard coat layer)

The composition for forming a hard coat layer contains the above-mentioned binder resin component and inorganic filler, and, if necessary, a solvent capable of dissolving the binder resin component. When the binder resin component is a curable resin, it is preferable that a suitable polymerization initiator is contained in the composition. For example, when the binder resin component is a photocurable resin, it is preferable that a photopolymerization initiator is contained in the composition. The composition for forming the hard coat layer may contain, in addition to the above, additives such as leveling agents, thixotropic agents, antistatic agents, antiblocking agents, dispersants, dispersion stabilizers, antioxidants, ultraviolet absorbers, antifoaming agents, thickeners, surfactants, and lubricants do.

A hard coat layer is formed by applying a composition for forming a hard coat layer on a film substrate and, if necessary, removing a solvent and curing the resin. As a coating method of the composition for forming a hard coat layer, any suitable method such as bar coat method, roll coat method, gravure coat method, rod coat method, slot orifice coat method, curtain coat method, fountain coat method, comma coat method, etc. Can be employed. The heating temperature after application may be set to an appropriate temperature depending on the composition of the composition for forming a hard coat layer, and is, for example, about 50°C to 150°C. When the binder resin component is a photocurable resin, photocuring is performed by irradiating active energy rays such as ultraviolet rays. The integrated light amount of the irradiated light is preferably about 100 to 500 mJ/cm 2.

<Characteristics of the hard coat film>

The thickness of the hard coat layer 11 is not particularly limited, but in order to realize high hardness, 1 µm or more is preferable, 2 µm or more is more preferable, 3 µm or more is more preferable, and 3.5 µm or more is particularly preferable. Do. On the other hand, if the thickness of the hard coat layer 11 is excessively large, segregation of the inorganic binder easily occurs, and the surface unevenness of the hard coat layer may not be properly formed, or the film strength may be lowered due to cohesive failure. . Therefore, the thickness of the hard coat layer 11 is preferably 10 μm or less, more preferably 9 μm or less, and even more preferably 8 μm or less.

The arithmetic average roughness Ra of the surface of the hard coat layer 11 (the surface opposite to the film base 10) is 2.5 nm or more. When Ra of the hard coat layer 11 is 2 nm or more, the adhesion with the inorganic thin film 5 formed thereon is high, and even if the optical laminate is exposed to light such as ultraviolet light for a long time, the hard coat layer 11 and the inorganic Peeling between the layers of the thin film 5 is unlikely to occur.

The larger Ra of the surface of the hard coat layer 11, the higher the adhesion between the hard coat layer and the inorganic thin film tends to be. Ra of the surface of the hard coat layer 11 is preferably 2.5 nm or more, more preferably 3 nm or more, and even more preferably 3.5 nm or more. As described above, the uneven shape of the surface of the hard coat layer 11 can be adjusted by adjusting the particle diameter or content of the inorganic filler. The arithmetic mean roughness Ra is calculated in accordance with JIS B 0601:1994 from an observation image of 1 μm in all directions using an atomic force microscope (AFM).

When the particle diameter of the inorganic filler is increased in order to increase the surface roughness of the hard coat layer 11, reflection, refraction, and scattering of light at the interface between the binder resin and the inorganic filler easily occurs, and the diffuse reflectance is high or the reflected light is colored blue It may be admitted. Therefore, the Ra of the hard coat layer 11 is preferably 10 nm or less, more preferably 7 nm or less, and even more preferably 6 nm or less. Ra of the hard coat layer 11 may be 5.5 nm or less.

As described above, the arithmetic average roughness Ra of the surface of the hard coat layer can be adjusted by adjusting the particle diameter or content of the inorganic filler in the hard coat layer. Moreover, Ra tends to become large, so that the thickness of a hard-coat layer is small. The surface shape of the hard coat layer may change depending on the compatibility of the base and the hard coat layer. For example, when a substrate having high compatibility with a binder resin in the hard coat layer forming material is used, the binder resin easily penetrates the substrate, the content of the binder resin contained in the hard coat layer becomes relatively small, and the inorganic filler Since the content of is relatively large, Ra of the hard coat layer tends to be large. Conversely, when a substrate having low compatibility with the binder resin is used, Ra of the hard coat layer tends to be small.

In the hard coat film of the present invention, b ^* of the diffuse reflection light of the hard coat layer is -0.2 or more. The diffuse reflection light spectrum of the hard coat film is irradiated with light from a D65 light source on the side of the hard coat layer 11 forming surface in a state in which the black material is laid on the non-forming surface of the hard coat layer of the film substrate 10 and the back surface reflection is excluded. It is measured by spectrophotometer (SCE) method using a spectrophotometer. Resultant spread on the basis of the reflection spectrum, such as the b ^* of the reflectance (L ^* a ^* b ^*) of the diffuse reflectance (Y value of tristimulus values), for each wavelength, and CIE1976 color space is obtained.

The smaller b ^* is, the more the reflected light is colored blue, and the larger b ^* is, the yellow is reflected color. In the optical laminate having a small amount of reflected light on the surface of the inorganic thin film 5, such as an antireflection film, the reflected light at the interface between the hard coat layer 11 and the inorganic thin film 5 is likely to be recognized. Particularly, when the diffuse reflectance (Y value) is small, since the blue-colored light is easily visible, when the b ^* of the diffusely reflected light of the hard coat layer is small, visibility of the image display device or the like tends to decrease.

In order to reduce the blue color of the diffuse reflection light, b ^* of the diffuse reflection light on the surface of the hard coat layer is preferably -0.1 or more, and more preferably 0.0 or more. When b ^* is excessively large, since the yellow group of the reflected light is conspicuous, b ^* of the diffuse reflected light on the surface of the hard coat layer is preferably 1.5 or less, more preferably 1 or less, still more preferably 0.5 or less, and less than 0.3 Especially preferred.

When the hard coat layer contains a submicron-sized filler, as the cause of the diffuse reflection light being colored, refraction, reflection and scattering of light at the interface between the binder resin and the filler can be considered. When the particle diameter of the filler is sufficiently smaller than the wavelength of visible light (for example, 30 nm or less), refraction, reflection, and scattering of visible light at the interface between the filler and the binder hardly occur. When the particle diameter of the filler is about 50 to 100 nm, light at a short wavelength visible short wavelength (300 to 500 nm) from ultraviolet light is easily refracted, reflected, and scattered at the interface between the binder resin and the filler. Therefore, it is considered that since the short wavelength component of visible light in the diffuse reflection spectrum increases and b ^* becomes small, the reflected light tends to be bluishly recognized.

As a method of reducing the visible light short wavelength component of the reflected light and increasing b ^* of the diffuse reflected light, a method of reducing the particle diameter of the inorganic filler and shifting the reflected light wavelength to the shorter wavelength side (ultraviolet side) and of the inorganic filler and the binder resin And reducing the refractive index difference to reduce refraction, reflection, and scattering of light at the interface.

In order to shift the reflected light wavelength to the ultraviolet side, it is preferable that the average primary particle size of the inorganic filler is 45 nm or less. In order to prevent the color of the reflected light by shifting the wavelength of light that is refracted, reflected, and scattered at the interface between the inorganic filler and the binder resin, the smaller the average primary particle diameter of the inorganic filler is, the more preferable.

In order to reduce the refractive index difference between the inorganic filler and the binder resin, and to reduce refraction, reflection, and scattering of visible short wavelength light (especially visible light having a wavelength of 450 nm or less) at the interface, the inorganic filler and the binder resin have a wavelength of 405 nm. It is preferable that the absolute value of the difference in refractive index (hereinafter simply referred to as "refractive index difference") is 0.09 or less. The smaller the refractive index difference between the inorganic filler and the binder, the smaller the refraction, reflection, and scattering of light at the interface between the inorganic filler and the binder resin. Therefore, the refractive index difference between the inorganic filler and the binder resin is ideally 0. In order to set b ^* of the diffuse reflection light on the surface of the hard coat layer to -0.2 or more, the difference in refractive index between the inorganic filler and the binder resin at a wavelength of 405 nm is preferably 0.07 or less.

From the above, in order to set b ^* of the diffuse reflection light on the surface of the hard coat layer to -0.2 or more, any of the following may be satisfied: (1) The average primary particle size of the inorganic filler is 45 nm or less; Or (2) the difference in refractive index between the inorganic filler and the binder resin at a wavelength of 405 nm is 0.07 or less.

As described above, in order to increase b ^* of the diffuse reflection light on the surface of the hard coat layer (close to 0), the smaller the refractive index difference between the inorganic filler and the binder resin is, the more preferable. However, since the filler is an inorganic material and the binder resin is an organic material, it is not easy to completely match the refractive indices of both. As described above, in order to increase the b ^* of the diffuse reflection light on the surface of the hard coat layer, the smaller the particle diameter of the inorganic filler is, the more preferably the average primary particle size should be 30 nm or less. However, when the particle diameter of the inorganic filler decreases, the unevenness of the surface of the hard coat layer decreases, and the adhesiveness between the hard coat layer and the inorganic thin film tends to decrease.

An inorganic filler in a range in which the b ^* of the diffuse reflection light on the surface of the hard coat layer is -0.2 or more, and the adhesion between the hard coat layer and the inorganic thin film is not lowered as a practical method for improving the adhesion between the hard coat layer and the inorganic thin film. And a method of reducing the average primary particle size of and reducing the difference in refractive index between the inorganic filler and the binder resin. For example, when the average primary particle size of the inorganic filler is 45 to 70 nm, the difference in refractive index between the inorganic filler and the binder resin at a wavelength of 405 nm is preferably 0.06 or less, more preferably 0.05 or less, and further 0.04 or less desirable.

When the average primary particle size of the inorganic filler is less than 45 nm, even if the refractive index difference between the inorganic filler and the binder resin is large, b ^* of the diffuse reflection light tends to be close to zero. However, it is not easy to make the particle diameter of the nanometer to submicron order completely uniform. Moreover, even when the average primary particle diameter of the inorganic filler is small, refraction, reflection, and scattering of light of a short wavelength of visible light occurs when a small amount of large particles of the particle diameter is contained. Therefore, even when the average primary particle size of the inorganic filler is 25 nm or more and less than 45 nm, the difference in refractive index at a wavelength of 405 nm between the inorganic filler and the binder resin is preferably small, preferably 0.09 or less, more preferably 0.07 or less , 0.06 or less is more preferable, and 0.05 or less is particularly preferable.

The diffuse reflectance at a wavelength of 380 nm on the surface of the hard coat layer is preferably 0.05% or less, more preferably 0.04% or less, and even more preferably 0.03% or less. The smaller the diffuse reflectance at a wavelength of 380 nm, the more preferable. It may be 0.02% or less or 0.01% or less. The diffuse reflectance (Y value) on the surface of the hard coat layer is preferably 0.09% or less, more preferably 0.05% or less, and even more preferably 0.03% or less. The smaller the diffuse reflectance, the more preferable it is, and may be 0.02% or less or 0.01% or less. As described above, the diffusion reflectance and the reflection Y value of short-wavelength light can be reduced by a method of reducing the difference in refractive index between the inorganic filler of the hard coat layer and the binder resin or a method of reducing the particle diameter of the inorganic filler.

[Formation of inorganic thin film]

By forming the inorganic thin film 5 on the hard coat layer 11 of the hard coat film 1, an optical laminate is obtained. Examples of the material for the inorganic thin film include metals and metal compounds (metal or semimetal oxides, nitrides, carbides, sulfides, fluorides, etc.). The inorganic thin film may be either conductive or insulating, or may be a semiconductor. Various functions are provided by forming the inorganic thin film on the hard coat layer. For example, as shown in Fig. 2, by stacking a plurality of thin films having different refractive indexes as inorganic thin films, an antireflection layer is formed to obtain an antireflection film with a hard coat. The film thickness of the inorganic thin film 5 (total film thickness when a plurality of thin films are included) is, for example, about 1 nm to 1 µm, and is appropriately adjusted according to the type of the thin film, the function of the optical laminate, or the like. do.

In the hard coat film of the present invention, the hard coat layer 11 includes a binder resin and an inorganic filler, and a predetermined uneven shape is formed on the surface of the hard coat layer 11 (interface with the inorganic thin film 5). Therefore, the optical laminate has excellent adhesion between the hard coat layer and the inorganic thin film. In addition, since b ^* of the diffuse reflection light on the surface of the hard coat layer is within a predetermined range, coloring of the reflected light of the optical layered body on which the inorganic thin film is formed can be suppressed.

Before forming the inorganic thin film 5 on the hard coat layer 11, the surface treatment of the hard coat layer 11 is aimed at further improving the adhesion of the hard coat layer 11 and the inorganic thin film 5, etc. May be carried out. Examples of the surface treatment include surface modification treatments such as corona treatment, plasma treatment, frame treatment, ozone treatment, primer treatment, glow treatment, alkali treatment, acid treatment, and treatment with a coupling agent. As a surface treatment, you may perform vacuum plasma treatment. The surface roughness of the hard coat layer can also be adjusted by vacuum plasma treatment. For example, when vacuum plasma treatment is performed at a high discharge power, Ra on the surface of the hard coat layer tends to be large. The discharge power of the vacuum plasma treatment (for example, argon plasma treatment) is about 0.5 to 10 kW, and preferably about 1 to 5 kW.

<Anti-reflection layer>

Hereinafter, an embodiment of forming an antireflection layer composed of a plurality of thin films having different refractive indices as an inorganic thin film will be described.

Generally, in the antireflection layer, the optical film thickness (the product of the refractive index and the thickness) of the thin film is adjusted so that the phases in which incident light and reflected light are reversed cancel each other. The multilayered laminate of a plurality of thin films having different refractive indices can reduce the reflectance in the broad wavelength range of visible light. Examples of the material of the thin film constituting the antireflection layer 5 include metal oxides, nitrides, and fluorides. The antireflection layer 5 is preferably an alternating laminate of a high refractive index layer and a low refractive index layer. In order to reduce reflection at the air interface, the thin film 54 formed as the outermost layer of the antireflection layer 5 (the layer farthest from the hard coat film 1) is preferably a low refractive index layer.

The high refractive index layers 51 and 53 have, for example, a refractive index of 1.9 or more, preferably 2.0 or more. Examples of high refractive index materials include titanium oxide, niobium oxide, zirconium oxide, tantalum oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and antimony-doped tin oxide (ATO). Especially, titanium oxide or niobium oxide is preferable. The low refractive index layers 52 and 54 have, for example, a refractive index of 1.6 or less, preferably 1.5 or less. Examples of the low-refractive-index material include silicon oxide, titanium nitride, magnesium fluoride, barium fluoride, calcium fluoride, hafnium fluoride, and lanthanum fluoride. Among them, silicon oxide is preferred. In particular, it is preferable to alternately stack the niobium oxide (Nb ₂ O ₅ ) thin films 51 and 53 as the high refractive index layer and the silicon oxide (SiO ₂ ) thin films 52 and 54 as the low refractive index layer. In addition to the low-refractive-index layer and the high-refractive-index layer, a medium refractive index layer having a refractive index of about 1.6 to 1.9 may be formed.

The film thickness of the high-refractive-index layer and the low-refractive-index layer is about 5 to 200 nm, respectively, and preferably about 15 to 150 μm. The film thickness of each layer may be designed such that the reflectance of visible light decreases depending on a refractive index or a stacked configuration. For example, as a stacked configuration of a high refractive index layer and a low refractive index layer, from the side of the hard coat film 1, the high refractive index layer 51 having an optical film thickness of about 25 nm to 55 nm, and the optical film thickness of 35 nm to 55 nm The four-layer configuration of the low-refractive-index layer 52 of about nm, the high-refractive-index layer 53 of the optical film thickness of about 80 nm to 240 nm, and the low-refractive-index layer 54 of the optical film thickness of about 120 nm to 150 nm is mentioned. have.

The antireflection layer 5 preferably has a primer layer 50 on the surface of the hard coat film 1 in contact with the hard coat layer 11, and a high refractive index layer and a low refractive index layer thereon.

Examples of the material constituting the primer layer 50 include metals such as silicon, nickel, chromium, tin, gold, silver, platinum, zinc, titanium, tungsten, aluminum, zirconium, and palladium; Alloys of these metals; Oxides, fluorides, sulfides or nitrides of these metals; And the like. Among them, the material of the primer layer is preferably oxide, and silicon oxide is particularly preferable. Since the silicon oxide has a small refractive index, it is possible to reduce reflection of visible light at the interface between the hard coat layer 11 and the primer layer 50.

The primer layer 50 is preferably an inorganic oxide layer with less oxygen than the stoichiometric composition. Among inorganic oxides having a non-stoichiometric composition, silicon oxide represented by the composition formula SiOx (0.5≦x<2) is preferable. In particular, by forming a silicon oxide layer having a non-stoichiometric composition as a primer layer 50 on the hard coat layer 11 containing silica particles as an inorganic filler, the primer layer 50 and the hard coat layer 11 are formed. It can be tightly adhered.

The thickness of the primer layer 50 is, for example, about 1 to 20 nm, preferably 2 to 15 nm, and more preferably 3 to 15 nm. When the film thickness of the primer layer is within the above range, adhesion to the hard coat layer 11 and high light transmittance can be achieved.

The film forming method of the thin film constituting the antireflection layer 5 is not particularly limited, and may be either a wet coating method or a dry coating method. In view of being able to form a thin film having a uniform film thickness, dry coating methods such as vacuum deposition, CVD, sputtering, and electron beam deposition are preferred. Especially, the sputtering method is preferable at the point which is excellent in the uniformity of a film thickness and is easy to form a dense film.

In the sputtering method, a thin film can be continuously formed while conveying a long hard coat film in one direction (longitudinal direction) by a roll-to-roll method. Therefore, the productivity of the optical thin film inorganic thin film provided with the inorganic thin film 5 on the hard coat film 1 can be improved. In particular, in the case of forming a plurality of thin films such as an antireflection layer on the hard coat layer, a plurality of thin films can be continuously formed by arranging a plurality of targets along the film conveying direction. It is preferable to form a thin film. In order to improve the productivity of the antireflection film, it is preferable to form all thin films constituting the antireflection layer 5 by sputtering.

In the sputtering method, film formation is performed while introducing an inert gas such as argon and a reactive gas such as oxygen into the chamber as necessary. The film formation of the oxide layer by sputtering can be performed by either a method using an oxide target or a reactive sputter using a metal target. In order to form a metal oxide at a high rate, reactive sputtering using a metal target is preferred.

The arithmetic average roughness Ra of the surface of the inorganic thin film 5 (the surface opposite to the hard coat film 1) may be, for example, 2 nm or more, 2.5 nm or more, 3 nm or more, or 3.5 nm or more. When the inorganic thin film 5 is formed by a dry process such as sputtering, it is easy to form an uneven shape reflecting the surface shape of the hard coat layer 11 as a base on the surface of the inorganic thin film 5. As described above, before the film formation of the inorganic thin film 5, by performing surface treatment such as plasma treatment, the roughness of the treated surface is increased, and as a result, the Ra of the inorganic thin film surface may be increased. In particular, in the plasma treatment, the higher the discharge power, the higher the Ra of the treated surface of the hard coat layer 11 and the inorganic thin film formed thereon.

[Additional layer to inorganic thin film]

In the optical laminate, an additional functional layer may be formed on the inorganic thin film 5. For example, an antireflection film disposed on the outermost surface of an image display device, a solar adjustment film attached to a glass window or a show window, etc., are susceptible to contamination (fingerprints, hands, dust, etc.) from the external environment. Particularly, when the silicon oxide layer is disposed as the low-refractive-index layer 54 on the outermost surface of the antireflection film 100 of FIG. 2, the wettability of the silicon oxide is high, and contaminants such as fingerprints and fingerprints adhere. easy. An antifouling layer (not shown) may be formed on the inorganic thin film 5 for the purpose of preventing contamination from the external environment or easily removing the attached contaminants.

When forming an antifouling layer on the surface of an antireflection film, from the viewpoint of reducing reflection at the interface, it is preferable that the difference in refractive index between the low refractive index layer 54 on the outermost surface of the antireflection layer 5 and the antifouling layer is small. The refractive index of the antifouling layer is preferably 1.6 or less, and more preferably 1.55 or less. As a material for the antifouling layer, a fluorine-containing silane-based compound, a fluorine-containing organic compound, or the like is preferable. The antifouling layer can be formed by a wet method such as a reverse coating method, a die coating method, a gravure coating method, or a dry method such as a CVD method. The thickness of the antifouling layer is usually about 1 to 100 nm, preferably 2 to 50 nm, more preferably 3 to 30 nm.

[How to use anti-reflection film]

The antireflection film which is one form of an optical laminated body is used, for example, arrange|positioning on the surface of an image display apparatus, such as a liquid crystal display and an organic EL display. For example, by arranging an antireflection film on a viewing side surface of a panel including an image display medium such as a liquid crystal cell or an organic EL cell, reflection of external light can be reduced and visibility of the image display device can be improved.

As described above, a laminate of a plurality of films may be used as the film base 10, and a hard coat layer 11 and an antireflection layer 5 may be formed thereon. Moreover, after forming the hard coat layer 11 and the antireflection layer 5 on the film base material 10, another film may be pasted on the non-forming surface of the hard coat layer of the film base material 10. For example, by attaching a polarizer to the non-forming surface of the hard coat layer of the film base 10, a polarizing plate with an antireflection layer can be formed.

As a polarizer, a dichroic substance such as iodine or a dichroic dye is adsorbed onto a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, or an ethylene-vinyl acetate copolymer-based partially saponified film. And a polyene-based alignment film such as a stretched product, a dehydration product of polyvinyl alcohol, or a dehydrochloric acid product of polyvinyl chloride.

Among them, polyvinyl oriented in a predetermined direction by adsorbing dichroic substances such as iodine or dichroic dye to polyvinyl alcohol-based films such as polyvinyl alcohol and partially formalized polyvinyl alcohol from the point of having a high degree of polarization. Alcohol (PVA)-based polarizers are preferred. For example, by performing iodine dyeing and stretching on a polyvinyl alcohol-based film, a PVA-based polarizer is obtained. As the PVA-based polarizer, a thin polarizer having a thickness of 10 μm or less can also be used. As a thin-shaped polarizer, for example, Japanese Patent Application Publication No. 51-069644, Japanese Patent Application Publication No. 2000-338329, WO2010/100917 pamphlet, Japanese Patent No. 4711205, Japanese Patent No.4751481, etc. And a thin polarizing film. Such a thin polarizer is obtained by a manufacturing method including, for example, a step of stretching a PVA-based resin layer and a resin substrate for stretching in the form of a laminate, and a step of dyeing iodine.

A transparent protective film may be formed on the surface of the polarizer for the purpose of protecting the polarizer or the like. The transparent protective film may be pasted only on one side of the polarizer or may be pasted on both sides. Generally, a transparent protective film is formed on the surface opposite to the surface on which the anti-reflection film is laid on the polarizer. On the laying surface of the antireflection film of the polarizer, since the antireflection film has a function as a transparent protection film, it is not necessary to form a transparent protection film, but a transparent protection film may be formed between the polarizer and the antireflection film.

As the material for the transparent protective film, the same material as described above is preferably used as the material for the transparent film base material. It is preferable to use an adhesive for bonding the polarizer and the transparent film. As the adhesive, bases based on acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyvinyl alcohols, polyvinyl ethers, vinyl acetate/vinyl chloride copolymers, modified polyolefins, epoxy polymers, fluorine polymers, rubber polymers, etc. A polymer can be used as appropriate. A polyvinyl alcohol-based adhesive is preferably used for the adhesion of the PVA-based polarizer.

In the present invention, by adding an inorganic filler to the hard coat layer and adjusting its particle diameter and refractive index, an optical laminate having high adhesion between inorganic hard films, such as a hard coat layer and an antireflection layer, and with reduced coloring of reflected light is obtained. . The image display device provided with the optical laminate of the present invention on the viewing side surface is excellent in durability, and since reflection of external light is suppressed and coloring of reflected light is small, visibility is excellent.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

[Assessment Methods]

<Arithmetic mean roughness Ra>

The arithmetic average surface roughness Ra of the hard coat layer was measured under the following conditions using an atomic force microscope (AFM).

Apparatus: Dimemsion 3100 manufactured by Bruker, Controller: NanoscopeV

Measurement mode: tapping mode

Cantilever: Si single crystal

Measurement field: 1 μm × 1 μm

<diffuse reflection characteristics>

A black acrylic plate (manufactured by Mitsubishi Chemical) having a thickness of 2 mm is pasted on a main surface of which the hard coat layer of the hard coat film is not formed via a transparent acrylic adhesive, and diffuse reflection spectrum (specular reflection removal (SCE) spectrum) A sample for measurement was prepared. This sample was irradiated with light of a D65 light source from the hard coat layer forming surface, and a diffuse reflection spectrum was measured using a spectrophotometer ("CM2600d" manufactured by Konica Minolta). From the obtained SCE spectrum, the wavelength was 380 nm. Diffuse reflectance, reflection Y value and b ^* were determined.

<visibility>

For each of the hard coat film and the antireflection film after formation of the antireflection layer, a black acrylic plate having a thickness of 2 mm with a transparent acrylic adhesive on the main surface where the hard coat layer of the hard coat film is not formed (manufactured by Mitsubishi Chemical) And the light of the white LED was irradiated from the direction of 45° to the normal of the main surface. The reflected light was observed with the naked eye in the direction of 70 to 80° with respect to the normal of the main surface, and visibility was evaluated according to the following criteria.

A: The reflected light is colorless

B: The reflected light is slightly white

C: The reflected light is bluishly recognized

<Adhesion test (accelerated light test)>

The film base side (non-reflective layer non-reflective surface) of the antireflection films of Examples and Comparative Examples was pasted on a glass plate via an acrylic transparent pressure sensitive adhesive, and a temperature of 40° C. was used by using a Suga Tester manufactured by “Ultraviolet Fade Meter U48”. The accelerated light test of 500 hours was performed under conditions of 20% humidity and radiant intensity (300 to 700 nm integrated roughness) of 500±50 W/m 2.

After the accelerated light test, cut marks were made at 1 mm intervals on the surface of the antireflection layer of the sample, and a checkerboard eye of 100 mass was formed. Next, to prevent the surface of the antireflection layer from drying, 2 ml of isopropyl alcohol was continuously added thereto, and a polyester wiper ("Anti-gold" manufactured by San Platec) fixed to a 20 mm-long SUS jig was checkered. Sliding from above (load: 1.5 kg, 1000 reciprocations). The number of checkered eyes in which the antireflection layer was peeled off in a region of 1/4 or more of the area of the mass was counted, and adhesion was evaluated according to the following criteria.

A: The number of peeling checkered eyes is within 10

B: Peeling checkered number of eyes is 11 to 30

C: 31-50 pieces of peeling checkered eyes

D: Peeling checkered number of eyes is 51 or more

[Production Example 1]

<Preparation of composition for forming hard coat layer>

Organo silica sol so that the amount of silica particles per 100 parts by weight of the resin component is 25 parts by weight in the ultraviolet curable acrylic resin composition (manufactured by DIC, trade name "GRANDIC PC-1070", refractive index at wavelength 405 nm: 1.55) ("MEK-ST-L" manufactured by Nissan Chemical Co., average primary particle size of silica particles (inorganic filler): 50 nm, particle size distribution of silica particles: 30 nm to 130 nm, solid content 30% by weight) and mixed, A composition for forming a hard coat layer was prepared. The refractive index of the silica particles at a wavelength of 405 nm was 1.47.

<production of hard coat film>

After drying the above composition on one side of a biaxially stretched acrylic film having a thickness of 40 µm made of an imidized MS resin produced in the same manner as in the ``transparent protective film 1A'' described in the example of JP 2017-26939 A. It was applied to a thickness of 6 µm, and dried at 80°C for 3 minutes. Thereafter, a high-pressure mercury lamp was used to irradiate ultraviolet rays having an accumulated light amount of 200 mJ/cm 2, and the coating layer was cured to form a hard coat layer.

<Formation of anti-reflection layer>

(Surface treatment)

Argon plasma treatment was performed on the surface of the hard coat layer with a discharge power of 1.0 Kw while conveying the hard coat film in a vacuum atmosphere of 0.5 Pa.

(Formation of primer layer and anti-reflection layer)

The plasma-treated hard coat film was introduced into a roll-to-roll sputter film forming apparatus, and the pressure inside the bath was reduced to 1 x 10 ^-4 Pa, and then the film was run while the substrate temperature was 20°C and a 5 nm silicon oxide primer was used. A layer, an Nb ₂ O ₅ layer of 16 nm, an SiO ₂ layer of 19 nm, an Nb ₂ O ₅ layer of 102 nm, and an SiO ₂ layer of 71 nm were sequentially formed on the surface of the hard coat layer to form an antireflection film. It was produced.

A pure Si target was used for film formation of the primer layer, and sputtering was performed under the conditions of input power: 500 W, sputter gas: Ar, and sputter pressure: 0.5 Pa. The Nb target was used for film formation of the Nb ₂ O ₅ layer, and sputtering was performed under the conditions of input power: 30 kW and sputter pressure: 0.5 P. A Si target was used for the film formation of the SiO ₂ layer, and sputtering was performed under the conditions of input power: 20 kW and sputter pressure: 0.5 Pa. In the film formation of the Nb ₂ O ₅ layer and the SiO ₂ layer, argon and oxygen were used as the sputtering gas, and the amount of oxygen introduced into the film forming mode to maintain the transition region was adjusted by plasma emission monitoring (PEM) control.

[Production Examples 2 to 10]

The type of resin, the particle diameter of the silica particles, and the amount of addition in the composition for forming a hard coat layer were changed as shown in Table 1. Except for that, in the same manner as in Production Example 1, a hard coat layer was formed, a surface treatment, and an antireflection layer were formed.

In Production Examples 4, 6, 9, and 10, an ultraviolet curable acrylic resin composition to which a silicone resin was added as a curable resin component was used, and the refractive index of the binder resin at a wavelength of 405 nm was reduced to 1.53.

In Production Examples 5 and 6, organo silica sol having an average primary particle size of 40 nm of silica particles was used as the inorganic filler component.

In Production Examples 7 to 10, an organo silica sol having an average primary particle size of 30 nm of silica particles was used as the inorganic filler component.

[Production Examples 11 to 14]

As a film base material, a 80-µm-thick triacetyl cellulose (TAC) film (“Fuji Tak” manufactured by Fuji Film) was used instead of the acrylic film, the type of the resin in the composition for forming a hard coat layer, the particle diameter of the silica particles, and The amount of addition and the thickness of the hard coat layer were changed as shown in Table 1. Except for that, in the same manner as in Production Example 1, a hard coat layer was formed, a surface treatment, and an antireflection layer were formed.

In Production Example 11, an organo silica sol having an average primary particle size of 20 nm of silica particles was used as the inorganic filler component.

In Production Example 12, as the inorganic filler component, an organo silica sol having an average primary particle size of silica particles of 100 nm was used.

In Production Example 13, the same organo silica sol as Production Examples 5 and 6 was used as the inorganic filler component, and in Production Example 14, the same organo silica sol as Production Examples 7 to 10 was used as the inorganic filler component.

[Production Example 15]

The hard coat layer was formed, the surface treatment, and the antireflection layer were formed in the same manner as in Production Example 11, except that the nano-silica particles were not contained in the composition for forming the hard coat layer.

Composition of the hard coat layer in the above Production Examples 1 to 15 (average primary particle size of the silica particles and the amount added to the binder resin, and the refractive index at a wavelength of 405 nm of the binder resin), arithmetic average of the surface of the hard coat layer Table 1 shows the optical properties (diffuse reflected light properties and visibility) of the roughness Ra and the hard coat film, and the visibility and adhesion test results of the antireflection film.

In Production Examples 1-3 using particles having an average primary particle diameter of 50 nm, the diffuse reflection light b ^{* on the} surface of the hard coat layer was less than -0.2, and the reflected light from the hard coat layer was bluish colored (visibility evaluation C). . Even in the antireflection film in which the antireflection layer was formed on the hard coat layer of these production examples, the reflected light was bluish colored.

In Production Example 4 using a binder resin having a lower refractive index than Production Examples 1 to 3, the adhesion between the hard coat layer and the antireflection layer was as good as in Production Example 3 (adhesion evaluation A), and the visibility of reflected light was improved compared to Production Example 3 (Both hard coat film and antireflection film visibility evaluation B). The same tendency was also observed in the contrast between Production Example 5 and Production Example 6 using particles having an average primary particle diameter of 40 nm. In Production Examples 7 to 10 using particles having an average primary particle diameter of 30 nm, regardless of the type (refractive index) of the binder resin, coloring of reflected light was not confirmed and visibility was good (both hard coat film and antireflection film were visible. Evaluation A). From these results, it can be seen that the reduction in the refractive index difference between the binder resin and the particle and the reduction in the particle diameter are effective for reducing the coloring of reflected light.

Also in Production Examples 11 to 15 in which the hard coat layer was formed on the TAC film, when the particle diameter and the added amount of the fine particles were changed, the surface shape of the hard coat layer changed, and as a result, there was a tendency that the visibility was changed. In Production Example 11 using particles having an average primary particle diameter of 20 nm, the visibility of the reflected light was good. In Production Example 15 in which the hard coat layer did not contain particles, in Production Example 12 using particles having an average primary particle diameter of 100 nm, which had good visibility of reflected light, the reflected light was bluish colored. From the results of Production Examples 11 to 15, it can be seen that, when the binder resin is the same, the smaller the arithmetic mean roughness Ra of the surface of the hard coat layer, the less the coloring of reflected light and the better the visibility.

In Production Example 15 in which the hard coat layer did not contain particles and Production Example 11 in which particles having a small particle diameter were used, the adhesion between the hard coat layer and the antireflection layer was lowered. In addition, from the contrast of Production Examples 1 to 3, as the particle content in the hard coat layer increased, the arithmetic average roughness Ra of the hard coat layer increased, and as a result, the adhesion between the hard coat layer and the antireflection layer improved. It can be seen that there is a tendency. On the other hand, in Production Example 12 using particles with a large particle diameter, despite the large arithmetic average roughness Ra of the surface of the hard coat layer, the adhesion was insufficient. From these results, it can be seen that increasing the addition amount of particles with small particle diameters and increasing the arithmetic average roughness Ra on the surface of the hard coat layer is effective for improving adhesion.

From the contrast of the above production example, by including the particles in the hard coat layer, the adhesion between the hard coat layer and the inorganic thin film formed thereon tends to be improved, whereas the reflected light may be bluish due to the presence of particles. You can see that In this invention, it turns out that coloring of reflected light can be prevented, maintaining high adhesiveness of a hard-coat layer and an inorganic thin film by adjusting particle diameter and content of a particle. From the contrast of Production Example 3 and Production Example 4 and the contrast between Production Example 5 and Production Example 6, it can be seen that reducing the difference in refractive index between the binder resin and particles constituting the hard coat layer is also effective in reducing the coloring of reflected light. .

1: Hard coat film
10: film base
11: hard coat layer
5: anti-reflection layer
50: primer layer
51, 53: low refractive index layer
52, 54: high refractive index layer
100: antireflection film

Claims (11)

As a hard coat film having a hard coat layer on the main surface of the film substrate,
The hard coat layer includes a binder resin and an inorganic filler,
The content of the inorganic filler relative to 100 parts by weight of the binder resin is 20 to 80 parts by weight,
The average primary particle diameter of the filler is 25 to 70 nm,
The hard coat film whose arithmetic average roughness of the surface of the said hard-coat layer is 2 nm or more, and b ^* of diffuse reflection light is -0.2 or more. According to claim 1,
The hard coat film whose absolute value of the difference of the refractive index in wavelength 405 nm of the said binder resin and the refractive index in wavelength 405 nm of the said inorganic filler is 0.09 or less. The method of claim 1 or 2,
The hard coat film, wherein the thickness of the hard coat layer is 1 to 10 μm. The method according to any one of claims 1 to 3,
The hard coat film whose Y value of the diffuse reflection light on the surface of the said hard coat layer is 0.09% or less. The method according to any one of claims 1 to 4,
The hard coat film whose diffusion reflectance at the wavelength 380 nm of the surface of the said hard coat layer is 0.05% or less. An optical laminate comprising the hard coat film according to any one of claims 1 to 5, and an inorganic thin film formed in contact with the hard coat layer of the hard coat film. The method of claim 6,
The inorganic thin film is an anti-reflection layer made of a plurality of inorganic thin films having different refractive indices. The method according to claim 6 or 7,
The inorganic thin film in contact with the hard coat layer is an inorganic oxide having a non-stoichiometric composition. The method of claim 8,
An optical laminate in which the inorganic thin film in contact with the hard coat layer is a silicon oxide thin film. The method according to any one of claims 6 to 9,
On the inorganic thin film, further comprising an antifouling layer, an optical laminate. An image display device in which the optical laminate according to any one of claims 6 to 10 is disposed on a viewing side surface of an image display medium.

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