Hard coat film and optical laminate

Abstract

This hard coat film comprises a transparent base material and a hard coat layer formed on the transparent base material, wherein the hard coat layer contains a filler and has a black luminance, measured under the following conditions, of less than 5.0 × 10-4 cd / m2. (Conditions: The hard coat film is provided adhering to an organic EL display having a light emission angle of 180 degrees and a luminance of 360 cd / m2; a white region and a black region are displayed in a checkerboard pattern at the organic EL display; a shielding plate is provided so as to cover the surface except for the black region of the organic EL display; and the black luminance for the black region is measured by a spectroradiometer provided at a distance of 60 cm from the organic EL display.)

Description

Hard-coated film and optical laminate

[0001] This application claims priority to Japanese Patent Application No. 2023-200677, filed on November 28, 2023, the contents of which are incorporated herein by reference.

[0002] Surface defects caused by scratches and fingerprints on displays lead to reduced visibility of the display. Therefore, hard coat films are often applied to the surface of displays to suppress surface defects. With the trend toward touch panels for various operating devices with displays, the importance of hard coat films is increasing, and it is said that the pencil hardness of the entire film formed on the display must be 3H or higher. Hard coat films with a dispersed filler to improve hardness are known.

[0003] In recent years, organic EL displays have become increasingly popular. Unlike liquid crystal displays, which use a backlight to illuminate the liquid crystal pixels, organic EL displays do not require a backlight because they utilize the self-luminescence of each pixel.

[0004] In a liquid crystal display, when black is displayed, the liquid crystal pixels are set to black, i.e., light from the backlight is blocked. However, the optical rotatory properties of liquid crystal molecules alone are not enough to block the light from the backlight, and some light may leak, resulting in poor brightness in the black region (black brightness). For this reason, a method is known for eliminating leaked light by phase difference using a polarizing plate or a material with low retardation for the liquid crystal display (for example, Patent Document 1).

[0005] In contrast, organic EL displays are known to have good black luminance because black can be displayed if each pixel is not made to emit light. In recent years, there has been a demand for further improvement in contrast in organic EL displays. To improve contrast, improving black luminance is important. The key factors for improving black luminance are thought to depend on the materials and structure of the organic EL display and the film used in the organic EL display.

[0006] Japanese Patent Application Laid-Open No. 2005-301227

[0007] When a hard coat film with dispersed fillers is applied to an organic EL display, light from an emitting region adjacent to a black region may leak into the black region, resulting in increased black luminance. Using a polarizing plate or a material with low retardation, as disclosed in Patent Document 1, in an organic EL display was not effective in addressing the black luminance issue. Furthermore, no hard coat film with dispersed fillers was known that could achieve black luminance that meets VESA's DisplayHDR500 True Black certification. Therefore, when applying a hard coat film with dispersed fillers to an organic EL display, another method for improving black luminance is required.

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a hard coat film and an optical laminate that have high hardness and good black brightness when applied to an organic EL display.

[0009] The present invention provides the following means to solve the above problems.

[0010] (1) A hard coat film according to one aspect of the present invention comprises a transparent substrate and a hard coat layer formed on the transparent substrate, wherein the hard coat layer contains a filler, and the black luminance measured under the following conditions is 5.0 × 10 －４ cd / m ２ (Conditions: luminous angle 180 degrees, luminance 360 ​​cd / m ２ A hard coat film is placed in close contact with the organic EL display, white and black areas are displayed in a checkerboard pattern on the organic EL display, a shielding plate is placed so as to cover the surface of the organic EL display excluding the black areas, and the black luminance in the black areas is measured using a spectroradiometer placed 60 cm away from the organic EL display.

[0011] (2) In the hard coat film of (1) above, the hard coat layer may contain an acrylic resin, the particle size of the filler may be 20 nm or more and 50 nm or less, and the surface of the filler may be modified with a (meth)acrylic group.

[0012] (3) In the hard coat film of (1) or (2) above, the hard coat layer may have a first layer separated from the transparent substrate and containing the filler, and a second layer provided between the transparent substrate and the first layer, and the second layer may contain a resin component of the transparent substrate and a resin component of the first layer.

[0013] (4) In the hard coat film of (3) above, the filler may have an average particle size of 20 nm or more and 50 nm or less, and the concentration of the filler in the first layer may be 25% or more and 65% or less.

[0014] (5) In the hard coat film of (1) or (2) above, the filler may have an average particle size of 20 nm or more and 50 nm or less, and the concentration of the filler in the hard coat layer may be 40% or more and 65% or less.

[0015] (6) An optical laminate according to one aspect of the present invention comprises the hard coat film according to any one of (1) to (5) above and an optical functional layer formed on the hard coat layer, wherein the optical functional layer is made of an inorganic oxide or an inorganic nitride.

[0016] (7) In the optical laminate of (6), the optical functional layer is made of SiO ２ It may also be a single layer film consisting of

[0017] (8) The optical laminate of (6) or (7) above may further include an adhesive layer formed between the hard coat layer and the optical functional layer and in contact with the hard coat layer and the optical functional layer, and the optical functional layer may be formed by alternately stacking high refractive index material layers and low refractive index layers, and the adhesive layer may be in contact with the high refractive index material layer.

[0018] According to the present invention, it is possible to provide a hard coat film and an optical laminate that have high hardness and good black brightness when applied to an organic EL display.

[0019] 10A is a cross-sectional view of a hard coat film according to one embodiment of the present invention. FIG. 10B is a diagram illustrating interfacial reflection when the hard coat film is applied to an organic EL display. FIG. 10C is a diagram illustrating interfacial reflection when the hard coat film is applied to an organic EL display. FIG. 10D is a diagram illustrating scattering when a hard coat film containing a filler is applied to an organic EL display. FIG. 10E is a diagram illustrating scattering when a hard coat film containing a filler is applied to an organic EL display. FIG. 10F is a diagram illustrating scattering when a hard coat film containing a filler is applied to an organic EL display. FIG. 10G is a diagram illustrating black luminance measured when the hard coat film of FIG. 1 is applied to an organic EL display. FIG. 10H is a graph illustrating a simulation of the correlation between the interparticle distance of the filler when light is incident in the in-plane direction from the side for a hard coat film 100A containing fillers with particle sizes of 22 nm, 42 nm, and 80 nm. FIG. 10H is a cross-sectional view showing a modified example of the hard coat film of FIG. 1. FIG. 10A is a diagram illustrating black luminance measured when the hard coat film of FIG. 1 is applied to an organic EL display, and FIG. 10B is a diagram illustrating black luminance measured when the hard coat film of FIG. 9 is applied to an organic EL display. 13 is a graph showing a simulation result of the correlation between the interparticle distance of the filler and the estimated luminance when light is incident laterally in the in-plane direction on hard coat films 100A and 100B containing a filler with a particle size of 42 nm. FIG. 14 is a graph showing a simulation result of the correlation between the interparticle distance of the filler and the estimated luminance when light is incident laterally in the in-plane direction on hard coat films 100A and 100B containing a filler with a particle size of 22 nm. FIG. 15 is a cross-sectional view of an optical laminate according to one embodiment of the present invention. FIG. 16 is a cross-sectional view of an optical laminate according to a modified example of FIG. 13. FIG. 17 is a cross-sectional view of an optical laminate according to another modified example of FIG. 13. FIG. 18 is a measurement pattern displayed on an organic EL when measuring black luminance in Examples and Comparative Examples. FIG. 19 is a graph showing the results of filler concentration and luminance for Examples 5 to 7 and Comparative Example 4.

[0020] The present embodiment will be described in detail below with reference to the drawings as appropriate. The drawings used in the following description may show characteristic portions enlarged for the sake of clarity, and the dimensional ratios of each component may differ from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto. Appropriate changes can be made within the scope of the present invention.

[0021] [Hard Coat Film] Fig. 1 is a cross-sectional view of a hard coat film according to one embodiment of the present invention. The hard coat film 100A shown in Fig. 1 comprises a transparent substrate 1 and a hard coat layer 2 formed on the transparent substrate 1. The hard coat layer 2 contains a filler 21. The hard coat film 100A has a black luminance of 5.0 × 10 measured under the following conditions. －４ cd / m ２ (Measurement conditions for black luminance: luminous angle 180 degrees, luminance 360 ​​cd / m ２ A hard coat film is provided on the organic EL display, and the black luminance is measured using a spectroradiometer placed 60 cm away from the organic EL display.) The conditions for measuring the black luminance will be described in detail later.

[0022] The hard coat film 100A is composed of, for example, a transparent substrate 1 and a hard coat layer 2 formed so as to be in contact with the transparent substrate 1.

[0023] (Transparent Substrate) The transparent substrate 1 may be formed from a transparent material that can transmit light in the visible light range. For example, a plastic film is preferably used as the transparent substrate 1. Specific examples of materials constituting the plastic film include polyester-based resins, acetate-based resins, polyethersulfone-based resins, polycarbonate-based resins, polyamide-based resins, polyimide-based resins, polyolefin-based resins, (meth)acrylic-based resins, polyvinyl chloride-based resins, polyvinylidene chloride-based resins, polystyrene-based resins, polyvinyl alcohol-based resins, polyarylate-based resins, and polyphenylene sulfide-based resins.

[0024] In the present invention, the term "transparent material" refers to a material having a transmittance of 80% or more for light in the wavelength range used, provided that the effect of the present invention is not impaired. In addition, in this embodiment, "(meth)acrylic" means methacrylic and acrylic.

[0025] The transparent substrate 1 may contain a reinforcing material as long as the optical properties are not significantly impaired. Examples of the reinforcing material include cellulose nanofiber and nanosilica. In particular, polyester-based resins, acetate-based resins, polycarbonate-based resins, and polyolefin-based resins are preferably used as the reinforcing material. Specifically, a triacetyl cellulose (TAC) substrate is preferably used as the reinforcing material. Furthermore, a glass film, which is an inorganic substrate, can also be used as the transparent substrate 1.

[0026] The transparent substrate 1 may be a film having optical and / or physical functions. Examples of films having optical and / or physical functions include a polarizing plate, a retardation compensation film, a heat-shielding film, a transparent conductive film, a brightness-enhancing film, and a barrier-enhancing film.

[0027] The thickness of the transparent substrate 1 is not particularly limited, but is preferably, for example, 25 μm or more. The film thickness of the transparent substrate 1 is more preferably 40 μm or more. When the thickness of the transparent substrate 1 is 25 μm or more, the rigidity of the substrate itself is ensured, and wrinkles are less likely to occur even when stress is applied to the optical laminate 10. In addition, when the thickness of the transparent substrate 1 is 25 μm or more, wrinkles are less likely to occur even when the hard coat layer 2 is continuously formed on the transparent substrate 1, which is preferable as there are fewer concerns about production. When the thickness of the transparent substrate 1 is 40 μm or more, wrinkles are even less likely to occur, which is preferable.

[0028] When production is carried out using a roll, the thickness of the transparent substrate 1 is preferably 1000 μm or less, and more preferably 600 μm or less. When the thickness of the transparent substrate 1 is 1000 μm or less, the optical laminate 10 during production and the optical laminate 10 after production can be easily wound into a roll, and the optical laminate 10 can be produced efficiently. Furthermore, when the thickness of the transparent substrate 1 is 1000 μm or less, the optical laminate 10 can be made thinner and lighter. When the thickness of the transparent substrate 1 is 600 μm or less, the optical laminate 10 can be produced more efficiently and can be made even thinner and lighter, which is preferable.

[0029] The surface of the transparent substrate 1 may be previously subjected to an etching treatment such as sputtering, corona discharge, ultraviolet irradiation, electron beam irradiation, conversion treatment, oxidation, etc., and / or a primer treatment. By previously performing these treatments, it is possible to improve adhesion to the hard coat layer 2 to be formed on the transparent substrate 1. Furthermore, before forming the hard coat layer 2 on the transparent substrate 1, it is also preferable to remove dust and clean the surface of the transparent substrate 1 by subjecting the surface of the transparent substrate 1 to solvent washing, ultrasonic cleaning, etc., as necessary.

[0030] (Hard Coat Layer) The hard coat layer 2 includes a binder resin 22 and a filler 21 as essential components, and may optionally contain other components such as a dispersant. Known binder resins can be used as the binder resin 22. The filler 21 is contained in the binder resin to the extent that transparency is not impaired. The filler 21 may be an organic filler, an inorganic filler, or a filler composed of both organic and inorganic materials. However, from the viewpoints of hardness and flex resistance, inorganic fillers are preferred, and silica particles made of silica are even more preferred. Furthermore, from the viewpoint of preventing the filler 21 from agglomerating and locally increasing the scattered light caused by the filler 21, surface-modified silica particles are particularly preferred because they have good dispersibility in the binder resin.

[0031] The binder resin used in the hard coat layer 2 is preferably transparent, and examples thereof include ionizing radiation curable resins that are cured by ultraviolet light or electron beams, thermoplastic resins, and thermosetting resins.

[0032] Examples of the ionizing radiation curable resin used as the binder resin of the hard coat layer 2 include ethyl(meth)acrylate, ethylhexyl(meth)acrylate, styrene, methylstyrene, N-vinylpyrrolidone, etc. Examples of the compound that is an ionizing radiation curable resin having two or more unsaturated bonds include trimethylolpropane tri(meth)acrylate, tripropylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane ... dipentaerythritol hexa(meth)acrylate, 1,6-hexanedi Examples of suitable polyfunctional compounds include erythritol penta(meth)acrylate, tripentaerythritol octa(meth)acrylate, tetrapentaerythritol deca(meth)acrylate, isocyanuric acid tri(meth)acrylate, isocyanuric acid di(meth)acrylate, polyester tri(meth)acrylate, polyester di(meth)acrylate, bisphenol di(meth)acrylate, diglycerin tetra(meth)acrylate, adamantyl di(meth)acrylate, isobornyl di(meth)acrylate, dicyclopentane di(meth)acrylate, tricyclodecane di(meth)acrylate, and ditrimethylolpropane tetra(meth)acrylate. Among these, pentaerythritol triacrylate (PETA), dipentaerythritol hexaacrylate (DPHA), and pentaerythritol tetraacrylate (PETTA) are preferably used. The term "(meth)acrylate" refers to methacrylate and acrylate. Furthermore, the ionizing radiation curable resin may be a resin obtained by modifying the above-mentioned compounds with PO (propylene oxide), EO (ethylene oxide), CL (caprolactone), or the like.Furthermore, urethane (meth)acrylate oligomers, epoxy (meth)acrylate oligomers, etc. can also be used from the viewpoint of film formation of the hard coat layer and adjustment of viscoelasticity.

[0033] Examples of thermoplastic resins used as the binder resin of the hard coat layer 2 include styrene-based resins, acrylic-based resins, (meth)acrylic-based resins, vinyl acetate-based resins, vinyl ether-based resins, halogen-containing resins, alicyclic olefin-based resins, polycarbonate-based resins, polyester-based resins, polyamide-based resins, cellulose derivatives, silicone-based resins, and rubber or elastomers. The thermoplastic resins are preferably amorphous and soluble in organic solvents (particularly common solvents capable of dissolving multiple polymers and curable compounds). In particular, from the viewpoints of transparency and weather resistance, styrene-based resins, acrylic-based resins, (meth)acrylic-based resins, alicyclic olefin-based resins, polyester-based resins, cellulose derivatives (cellulose esters, etc.), and the like are preferred.

[0034] The hard coat layer 2 contains, for example, a binder resin 22 and silica particles as fillers 21. As described above, the silica particles preferably contain silica particles that have been surface-modified in advance. The surface modification is preferably performed using a silane compound having a functional group. The surface of the filler 21 is preferably modified with a (meth)acrylic group.

[0035] Specific examples of silane compounds include vinyl group-containing silane compounds, (meth)acryloyl group-containing silane compounds, amino group-containing silane compounds, isocyanate group-containing silane compounds, isocyanurate group-containing silane compounds, epoxy group-containing silane compounds, and mercapto group-containing silane compounds. These may be used alone or in combination. The silane compound is appropriately selected depending on the type of binder resin. When the binder resin contains a functional group, a silane compound having the same functional group as the binder resin is preferred. For example, when the binder resin contains a (meth)acrylate compound as an ionizing radiation-curable resin, the silane compound is preferably a (meth)acryloyl group-containing alkoxysilane compound. Note that "(meth)acrylate" refers to methacrylate and / or acrylate. The silane compound used for surface modification preferably has an alkoxysilyl group or a silanol group at its terminal, as this improves bonding with the hydroxyl groups present on the silica particle surface.

[0036] By preliminarily surface-modifying the silica particles, the dispersibility in the binder resin 22 is improved, and the reaction between the surface treatment agent used for surface modification and the binder resin causes the particles to bond more firmly with the binder resin 22, thereby increasing hardness.

[0037] The average particle size of the filler 21 is, for example, 10 nm or more and 100 nm or less, preferably 20 nm or more and 50 nm or less, and more preferably 20 nm or more and 30 nm or less, although this depends on the concentration of the filler 21 in the hard coat layer 2. Furthermore, from the viewpoint of suppressing unevenness in appearance in optical applications, the average particle size of the filler 21 is preferably 50 nm or less.

[0038] When the average particle size of the filler 21 in the hard coat layer 2 is within the above range, the haze value is at least 2%. When the haze value is 2% or less, the hard coat film 100A has high transparency and becomes a clear hard coat film. Furthermore, taking into consideration the appearance and optical characteristics of the display, it is considered preferable that the haze value be 1% or less, and when the average particle size of the filler 21 is within the above range, this haze value can be achieved. Specifically, a low haze value suppresses contrast.

[0039] The concentration of the filler 21 in the hard coat layer 2 is, for example, more than 0% and not more than 80%. As will be described in detail later, the black luminance depends on the concentration (interparticle distance) of the filler 21 and the particle size of the filler 21 in the hard coat layer 2, which is the region where the filler 21 is present in the hard coat film 100A.

[0040] When the average particle size of the filler 21 in the hard coat layer 2 is 30 nm or more and 50 nm or less, the concentration of the filler 21 in the hard coat layer 2 is preferably 23% or more and 50% or less, or more than 0% and 12% or less, and more preferably 30% or more and 45% or less. When the average particle size of the filler 21 in the hard coat layer 2 is 10 nm or more and less than 30 nm, the concentration is preferably more than 0% and 30% or less. However, from the viewpoint of increasing the surface hardness of the hard coat film and the optical laminate described later, a higher concentration is preferable.

[0041] As the filler contained in the hard coat layer 2, various reinforcing materials can be used within a range that does not impair the optical properties in order to impart toughness to the hard coat layer 2. Examples of reinforcing materials include cellulose nanofibers.

[0042] The thickness of the hard coat layer 2 is preferably 0.5 μm or more, more preferably 1 μm or more. The thickness of the hard coat layer 2 is preferably 100 μm or less, more preferably 30 μm or less. When the thickness of the hard coat layer 2 is 0.5 μm or more, sufficient hardness is obtained, making it less susceptible to scratches during production. Furthermore, when the thickness of the hard coat layer 2 is 100 μm or less, the hard coat film 100A can be made thinner and lighter. Furthermore, when the thickness of the hard coat layer 2 is 100 μm or less, microcracks in the hard coat layer 2 that occur when the hard coat film 100A is bent during production are less likely to occur, improving productivity.

[0043] The hard coat layer 2 may be a single layer or may be a laminate of multiple layers. When the hard coat layer 2 is a laminate of multiple layers, a filler may be dispersed in each layer, or may be contained only in the layer farther from the transparent substrate 1. The hard coat layer 2 may further be imparted with known functions such as ultraviolet absorption performance, antistatic performance, refractive index adjustment function, and hardness adjustment function. The functions imparted to the hard coat layer 2 may be imparted to a single hard coat layer or may be imparted to multiple layers separately.

[0044] The hard coat film 100A according to the above embodiment exhibits a high pencil hardness exceeding 3H, and exhibits good black luminance when applied to an organic EL display. That is, in an area (black area) where non-self-emissive pixels are located and adjacent to an area where self-emissive pixels are located in an organic EL display, light from each self-emissive pixel can be prevented from leaking due to interfacial reflection or scattering, resulting in an increase in black luminance.

[0045] The function of the hard coat film shown in FIG. 1 will be described below with reference to the accompanying drawings as appropriate. FIGS. 2 and 3 are diagrams illustrating interfacial reflection when a hard coat film is applied to an organic EL display. As an example, FIGS. 2 and 3 show a case in which the hard coat film 100A shown in FIG. 1 is formed on an organic EL display OLED, a shielding plate 30 having an opening is formed on the hard coat film 100A, and the luminance (black luminance) of a black region of the organic EL display OLED is measured through the opening with a spectroradiometer 40. The filler 21 is omitted to simplify the explanation of interfacial reflection. Although FIGS. 2 and 3 show the hard coat film 100A separated from the organic EL display OLED and the shielding plate 30 for ease of explanation, the hard coat film 100A is in contact with the organic EL display OLED and the shielding plate 30. Hereinafter, a case will be considered in which the distance between the spectroradiometer 40 and the organic EL display OLED in the direction perpendicular to the surface of the organic EL display OLED is 60 cm (measurement angle: 2°), and the distance between the white region W and the spectroradiometer 40 in the in-plane direction of the organic EL display OLED is 50 mm.

[0046] 2, when each pixel in an organic EL display OLED is divided into a self-luminous region and a non-self-luminous region, and white regions W and black regions B are displayed in a checkerboard pattern, light L emitted from the white region W is reflected by the interface many times within the hard coat film 100A. With each interface reflection, photon energy is lost, and the light energy detected by the spectroradiometer 40 becomes a small value.

[0047] As shown in Figure 3, light L emitted from the white region W partially passes through the hard coat film 100A as direct transmission light, partially reflects at the interface and becomes internally reflected light, and passes through the opening in the shielding plate 30 after a smaller number of interface reflections than in the example shown in Figure 2. However, due to the large angle, this light that passes through the opening in the shielding plate 30 is not detected as a signal by the spectroradiometer 40. In Figures 2 and 3, the distance between the white region W and the spectroradiometer 40 in the in-plane direction of the organic EL display OLED is larger than the distance between the white region W and the spectroradiometer 40 in the perpendicular direction to the surface of the organic EL display OLED. Therefore, it is considered that the influence of the light emitted from the white region W and reflected at the interface on the black region B is small. Note that Figures 2 and 3 are intended to explain the influence of interface reflection in the hard coat film without taking into account the influence of the filler. In an actual hard coat film 100A, a phenomenon different from that shown in Figures 2 and 3 occurs, and a detailed explanation will be provided below with reference to Figure 7 and subsequent figures.

[0048] Next, the effect of filler scattering when a filler is contained in a hard coat film will be described using FIGS. 4 to 6 . FIGS. 4 to 6 are diagrams illustrating scattering when a hard coat film containing a filler is applied to an organic EL display. As an example, FIGS. 4 to 6 show a hard coat film 100A shown in FIG. 1 formed on an organic EL display OLED, a shielding plate 30 formed on the hard coat film 100A, and a spectroradiometer 40 used to measure the luminance (black luminance) in the black region of the organic EL display OLED. To simplify the explanation of scattering by the filler 21, only one filler 21 is shown, and scattering by the filler 21 will be described. In FIG. 4 , a filler located directly above the white region W is illustrated, while in FIGS. 5 and 6 , a filler located directly below the opening of the shielding plate 30 and directly above the black region B is illustrated. These illustrated fillers are merely used to explain the effect of the filler at that position on the black luminance; the hard coat film 100A actually contains multiple fillers, not just one.

[0049] As shown in Fig. 4, when filler 21 is located above white region W, light L emitted from white region W is scattered when it reaches filler 21. When the particle size of filler 21 is approximately 50 nm or less, visible light is scattered by Rayleigh scattering, and Fig. 4 shows how the scattered light spreads concentrically. Due to the positional relationship between the opening in shading plate 30 and spectroradiometer 40, light scattered above white region W is not detected as a signal by spectroradiometer 40.

[0050] Here, the scattered light I of Rayleigh scattering for one particle is calculated by the following formula (1). As can be seen from formula (1), the scattered light I of Rayleigh scattering is highly dependent on the particle size. For example, when the refractive index is 1.5, the wavelength is 780 nm, and the particle size is 42 nm, the scattered light I of one particle is calculated by the following formula (1): ０ 1.3 x 10 －７ This means that most of the incident light does not become scattered light but travels straight (becomes transmitted light).

[0051] (In formula (1), I ０ : incident light, R: interparticle distance, λ: light wavelength, n: spatial refractive index, d: particle size)

[0052] 5, when the filler 21 is located directly below the spectroradiometer 40, light L emitted at an angle from the white region W reaches the filler 21 directly and is detected as a signal by the spectroradiometer 40 through the aperture. In other words, such scattered light by the filler 21 leads to an increase in the luminance in the black region, which can be said to lead to an increase in black luminance.

[0053] As shown in Fig. 6, consider light L emitted from the white region W at a smaller angle than in the example shown in Fig. 5 when the filler 21 is located directly below the spectroradiometer 40. The light L is reflected at the interface of the hard coat film 100A, and photon energy is lost at each interface reflection, in the same principle as in the case shown in Fig. 3. However, when the light L reaches the filler 21, scattering occurs, and the scattered light is detected as a signal by the spectroradiometer 40. In other words, such scattered light by the filler 21 leads to an increase in luminance in the black region B, leading to an increase in black luminance.

[0054] As explained using FIGS. 2 to 6, when focusing on one filler, the black luminance becomes a high value due to scattering by the filler 21 located directly below the spectroradiometer 40. The larger the particle size of the filler, the greater the scattered light caused by the filler. However, when a large number of fillers are contained in the hard coat film, such as the hard coat film 100A, it is extremely unlikely that the light emitted from the white region W will reach the filler 21 located directly below the spectroradiometer 40 without being affected by the other fillers 21, and it is therefore necessary to take into consideration the influence of multiple fillers 21. That is, the (1+cos 2 θ) / 2R 2 The value of must be taken into account.

[0055] 7 is a diagram illustrating the black luminance measured when the hard coat film of Fig. 1 is applied to an organic EL display. The spectroradiometer 40 detects, as a signal, the light scattered by the filler 21 located in the measurement region Ra located directly below the hard coat layer 2, but does not directly detect, as a signal, the light scattered by the filler 21 located in the intermediate region Rb located in the in-plane direction of the measurement region Ra.

[0056] On the other hand, as shown in Figure 7, in a hard coat film 100A containing a large number of fillers, the scattered light from the fillers 21 located in the intermediate region Rb reaches the fillers 21 located in the measurement region Ra and is scattered, thereby being detected as a signal (scattered luminance signal). The light that reaches the fillers 21 located in the intermediate region Rb includes light emitted from the white region W and reaching the filler directly, light that reaches the filler after interfacial reflection, and scattered light from other fillers. Of these, light other than the light emitted from the white region W and reaching the filler directly loses photon energy due to scattering or interfacial reflection. The scattering loss, which is the loss due to scattering in the intermediate region Rb, increases with increasing filler 21 concentration and with increasing particle size of the filler 21.

[0057] On the other hand, as described above, the black luminance increases due to the influence of scattered light by the filler 21 in the measurement region Ra. Focusing on the measurement region Ra, the scattered light from the filler 21 in the measurement region Ra, which affects the black luminance, increases as the particle size of the filler 21 increases and as the concentration of the filler 21 increases. Therefore, it has been found that in order to achieve high hardness and low black luminance, it is important to optimize the particle size and concentration of the filler 21 in the hard coat layer 2.

[0058] To summarize, the measurement conditions of the present invention focus on light leakage from the white area W to the black area B, and evaluation is performed by blocking direct light from the white area W. Light reaching the measurement area Ra in front of the black area B is reflected and scattered within the hard coat film 100A. The emission angle of the organic EL display OLED is wide (approximately 180°), and light enters the hard coat film at various angles. Light with a small incident angle reaches the front of the black area, undergoing many interfacial reflections and resulting in an extremely weak signal. Light with a large incident angle is mainly scattered by the filler 21 distributed in the hard coat layer 2 and transmitted to the measurement area Ra in front of the black area B.

[0059] The generation of electric dipoles is the main cause of scattering, and the likelihood of this occurring is closely related to particle size. Particles that are relatively small relative to the wavelength qualify as Rayleigh scattering particles, while larger particles qualify as Mie scattering particles. In optical applications, a particle size of 50 nm or less is preferred to avoid uneven appearance, and scattering at this particle size is generally classified as Rayleigh scattering. In this case, the scattered light from a single particle is related to the refractive index and particle size of the substance. Since the refractive index of the binder resin 22 in the hard coat layer 2 does not change significantly, the larger the particle size of the filler 21, the stronger the scattered light will generally be.

[0060] The amount of scattered light from a single filler particle 21 is very small compared to the incident light, and most of the light is transmitted without scattering. The light reaching the black region B is closely related to the optical path length and the filler concentration in the region where the filler particles 21 are present. In particular, the filler concentration is related to the probability of scattering, and is therefore a factor that determines the final scattering intensity. The optical path length here is the average length of light traveling through the hard coat film from the white region to the black region. Scattering that occurs along the optical path results in losses and weakens the transmitted light. The transmitted light arrives in front of the black region (measurement area Ra), and the light scattered in this area becomes a luminance signal, degrading the true black. When the filler concentration is high, the scattering intensity is strong, weakening the transmitted light, but the scattered luminance signal is strong. Therefore, depending on the filler concentration, there may be extreme values ​​in the luminance of the black region. The relationship between particle size and scattering intensity has already been discussed, but the relationship with the optical path length is also the reason why leakage light is strong in black regions close to the white region and weak in black regions far away.

[0061] The present inventors conducted a simulation to find the correlation between the filler concentration (interparticle distance), filler particle size, and black luminance in the hard coat layer 2 .

[0062] Fig. 8 is a graph showing a simulation of the correlation between the approximate brightness and the interparticle distance of the filler when light is incident from the side in the in-plane direction on a hard coat film 100A containing fillers with particle sizes of 22 nm, 42 nm, and 80 nm. The graph shown in Fig. 8 shows a simulation of the brightness measured by a spectroradiometer installed 60 cm away from the hard coat film through a shielding plate having an opening formed on the hard coat film, the opening being located approximately 50 nm in the in-plane direction from the edge of the hard coat film. The incident light has a brightness of 360 cd / m ２ This assumes the introduction of the following.

[0063] In Fig. 8, the horizontal axis represents the average distance between fillers, and the vertical axis represents the approximate luminance in the black region. That is, for example, in the graph of the simulation results for a particle size of 22 nm, the result where the filler distance is 22 nm is the result of the condition where the fillers in the hard coat layer 2 are in contact with each other. Note that the simulation results shown in Fig. 8 take into account Rayleigh scattering by the filler, but do not take into account scattering by the resin contained in the hard coat layer 2 or scattering by the transparent substrate. Therefore, when actually measured under each condition, the black luminance is considered to be higher than the approximate luminance value in Fig. 8. The increase in the value is about 2.2 × 10 when an 80 μm TAC film is used as the substrate. －４ cd / m ２ The degree of increase.

[0064] As shown in Figure 8, in a hard coat film containing a filler particle size of 22 nm, there is no maximum value in the graph of estimated luminance versus filler distance. That is, the larger the filler distance and the lower the concentration of filler 21 in the hard coat layer 2, the lower the estimated luminance. On the other hand, in hard coat films containing filler particle sizes of 42 nm and 80 nm, maximum values ​​are observed. That is, when the filler size is equal to or greater than a predetermined value, the black luminance increases as the filler distance increases to a predetermined value and the concentration decreases. When the filler distance exceeds a predetermined value, the black luminance decreases as the filler distance increases and the concentration decreases. The maximum value in the simulation results is thought to be due to the correlation between the magnitude of scattering loss in the intermediate region Rb and the magnitude of scattered light relative to the light reaching the filler in the measurement region Ra. Furthermore, the filler distance at which the maximum value is reached is thought to depend on the filler particle size, the optical path length, which is the average length of light transmitted through the hard coat film from the white region W to the black region B, and the thickness of the layer in which the filler is distributed.

[0065] Although it is difficult to strictly express the relationship between particle concentration and interparticle distance, considering the influence of particle size and inter-filler distance on brightness, in a hard coat film containing filler 21 having an average particle size of less than 30 nm in the hard coat layer 2, the filler 21 concentration in the hard coat layer 2 is preferably set to a concentration such that the inter-filler distance is 25 nm or more, and simulation results showed that the concentration at this time was 44.5% or less in the hard coat layer 2. In a hard coat film containing filler 21 having an average particle size of 30 nm or more and 50 nm or less in the hard coat layer 2, the filler concentration in the hard coat layer 2 is preferably a concentration such that the inter-filler distance is 45 nm to 60 nm and a concentration such that the inter-filler distance is 280 nm or more, and in the former case, the simulated value was 35% or more and 60% or less. Furthermore, the simulated value for the concentration such that the inter-filler distance is 280 nm or more was 0.3% or less. However, the concentration calculated in the simulation is the final filler concentration in the hard coat layer 2, not the concentration at the time of blending including the solvent.

[0066] Fig. 9 is a cross-sectional view of a hard coat film according to a modified example of Fig. 1. In the hard coat film 100B shown in Fig. 9, a hard coat layer 2X is separated from a transparent substrate 1, and the hard coat film 100B has a first layer 2a containing a filler 21 and a second layer 2b provided between the transparent substrate 1 and the first layer 2a. The second layer 2b contains the resin component of the transparent substrate 1 and the resin component of the first layer 2a.

[0067] In the first layer 2a, filler 21 is dispersed in binder resin 22. The second layer 2b is, for example, a region that does not contain filler 21, and the boundary between the first layer 2a and the second layer 2b is parallel to the transparent substrate 1 and is the plane where the filler 21 closest to the transparent substrate 1 is located; specifically, the end of the filler 21 closest to the transparent substrate 1 on the transparent substrate 1 side can be used as the reference.

[0068] The thickness of the first layer 2a in the hard coat layer 2X is, for example, 5 μm to 15 μm, which is 40% to 80% of the thickness of the hard coat layer 2X. When the average particle size of the filler 21 is 20 nm to 30 nm, the filler concentration in the first layer 2a of the hard coat layer 2X is, for example, 10% to 80%, preferably 25% to 65%. When the average particle size of the filler 21 is 30 nm to 50 nm, the filler concentration in the first layer 2a of the hard coat layer 2X is, for example, 10% to 80%, preferably 25% to 65%.

[0069] Depending on the resin composition and transparent substrate 1 used in forming the hard coat layer, the hard coat layer 2X has a first layer 2a containing a filler 21 and a second layer 2b disposed between the transparent substrate 1 and the first layer 2a and containing the same resin components as those contained in the transparent substrate 1 and the first layer 2a. The resin contained in the second layer 2b is not particularly limited, and may be a simple mixture (compatibility) of the resin constituting the transparent substrate 1 and the resin contained in the hard coat layer 2X. Furthermore, the resin contained in the second layer 2b may be a resin constituting the transparent substrate 1 or a resin contained in the first layer 2a that has undergone a chemical change due to heating, light irradiation, or the like.

[0070] A method for forming the second layer 2b includes using a solvent that dissolves / disperses the constituent resins when forming the hard coat layer 2X on the transparent substrate 1, and that also dissolves the transparent substrate 1. The transparent substrate 1 is selected from the group consisting of triacetyl cellulose (TAC), polyethylene terephthalate, polycarbonate, and acrylic, and the resin composition used to form the hard coat layer is selected from a solvent containing propylene glycol monomethyl ether acetate (PGMAC), butyl acetate, cyclohexanone (ANON), or the like. This dissolves the transparent substrate 1, resulting in a hard coat layer 2X having a second layer 2b between the first layer 2a and the transparent substrate 1, as shown in FIG. 9. When the hard coat layer 2 as shown in FIG. 1 contains a binder resin 22 and a filler 21, i.e., is configured as a first layer, the above-mentioned materials may not be used as the solvent when preparing the hard coat layer, and a resin composition containing propylene glycol monomethyl ether (PGM) or the like may be used as the solvent. The solvent is appropriately selected taking into consideration the type of transparent substrate 1 to be used and the solubility therein.

[0071] When a resin composition containing a solvent that dissolves the transparent substrate 1 as described above is applied and cured by irradiation with light including UV, a hard coat layer 2X is formed on one surface of the transparent substrate, and a penetration layer (second layer) containing the components of the binder resin 22 that constitutes the hard coat layer 2X and the resin components of the transparent substrate 1 is formed by penetration. The thickness of the transparent substrate 1 becomes slightly smaller due to the dissolution of the hard coat layer 2X by the solvent and the penetration of the resin components.

[0072] By selecting a material that will form the second layer 2b, the overall thickness of the transparent substrate 1 and the hard coat layer 2X can be maintained as desired, while adjusting the configuration of the first layer 2a, which is the region where the filler 21 is present, to obtain desired optical properties. The thicknesses of the first layer 2a and the second layer 2b can be adjusted by the type and amount of the solvent. As a result of forming the permeation layer in this manner, the adhesion between the transparent substrate 1 and the hard coat layer 2 is improved, and the occurrence of interference fringes due to the difference in refractive index between the layers can be suppressed.

[0073] FIG. 10(a) is a diagram illustrating the black luminance measured when the hard coat film of FIG. 1 is applied to an organic EL display, and FIG. 10(b) is a diagram illustrating the black luminance measured when the hard coat film of FIG. 9 is applied to an organic EL display.

[0074] The content of filler 21 in the hard coat layer 2 of the hard coat film 100A shown in FIG. 10 is the same as the content of filler 21 in the hard coat film 100B shown in FIG. 10 . However, compared with the hard coat layer 2 of the hard coat film 100A shown in FIG. 10 , which is the region where the filler 21 is present, the first layer 2a of the hard coat film 100B shown in FIG. 10 has a higher filler concentration. Specifically, the filler concentration increases by a factor of {(thickness of the hard coat layer 2) / (thickness of the first layer 2a)}. Accordingly, the filler concentration in the measurement region Ra measured by the spectroradiometer 40 also increases by the same factor. Therefore, the transmitted light in the intermediate region Rb decreases, and the optical properties of the hard coat film 100B can be changed without changing the total thickness of the transparent substrate and the hard coat layer.

[0075] Fig. 11 is a graph showing a simulation of the correlation between the interparticle distance of the filler and the approximate luminance when light is incident in the in-plane direction from the side on hard coat films 100A and 100B containing filler with an average particle size of 42 nm. The simulation of Fig. 11 uses a shielding plate with an opening similar to that in the simulation of Fig. 8 and a spectroradiometer, and simulates the luminance of light incident from the side of the hard coat film and detected through the opening.

[0076] 11 shows graphs of a hard coat film in which the hard coat layer is formed from the same material and has a uniform thickness of 10 μm in relation to the transparent substrate, and a hard coat film in which the hard coat layer is composed of a first layer with a thickness of 6 μm and a second layer with a thickness of 4 μm. That is, under the condition that the filler distance is the same, the filler concentration in the first layer of the latter is 1.67 times that of the former hard coat layer.

[0077] 12 is a graph showing a simulation of the correlation between the interparticle distance of the filler particles and the estimated luminance when light is incident in the in-plane direction from the side on hard coat films 100A and 100B containing filler particles with a particle size of 22 nm, where the only difference between the simulations in FIG. 11 is the particle size of the filler particles, and the other conditions are the same.

[0078] 11 and 12 , it was confirmed that regardless of the particle size of the filler used in the range of 20 to 45 nm, the estimated luminance varied depending on whether the hard coat layer had a homogeneous structure or a structure having a first layer containing the filler and a second layer of resin formed between the first layer and the transparent substrate. Specifically, it was confirmed that a hard coat film having a hard coat layer consisting of a first and second layer exhibited a lower estimated luminance than a hard coat film consisting of a first layer. Furthermore, regardless of the filler particle size, the way in which the estimated luminance changed with respect to the filler distance was the same regardless of whether the second layer was present or not, and it was confirmed that when the filler particle size was 42 nm, the maximum value was reached when the filler distance was approximately 110 nm.

[0079] According to the hard coat films 100A and 100B of the above-described embodiments, the hard coat layers 2 and 2X contain the filler 21, and the concentration and particle size of the filler 21 are adjusted. Therefore, when applied to an organic EL display, the black luminance of 5.0×10, which is the standard called True Black, can be achieved. －４ cd / m ２Thus, the hard coat films 100A and 100B according to the above embodiment can achieve excellent black luminance.

[0080] [Optical Laminate] Fig. 13 is a cross-sectional view of an optical laminate according to one embodiment of the present invention. The optical laminate 200A shown in Fig. 13 includes the hard coat film 100A according to the above embodiment and an optical functional layer 50A formed on the hard coat layer 2, the optical functional layer 50A being composed of a layer made of an inorganic oxide or an inorganic nitride. Here, "on the hard coat layer 2" does not necessarily mean being provided in contact with the hard coat layer 2, but may also be formed via another layer. The optical laminate 200A further includes, for example, an adhesion layer 3 formed between the hard coat layer 2 and the optical functional layer 50A and in contact with the hard coat layer 2 and the optical functional layer 50A, and an antifouling layer 6 formed on the optical functional layer 50A.

[0081] (Adhesion Layer) The adhesion layer 3 is a layer formed to improve adhesion between the hard coat layer 2, which is an organic film, and the optical function layer 50A, which is an inorganic film. The adhesion layer 3 is preferably made of an oxygen-deficient metal oxide or metal. An oxygen-deficient metal oxide refers to a metal oxide in which the number of oxygen atoms is deficient compared to the stoichiometric composition. Examples of oxygen-deficient metal oxides include SiOx, AlOx, TiOx, ZrOx, CeOx, MgOx, ZnOx, TaOx, SbOx, SnOx, and MnOx. Examples of metals include Si, Al, Ti, Zr, Ce, Mg, Zn, Ta, Sb, Sn, Mn, and In. The adhesion layer 3 may be, for example, SiOx, where x is greater than 0 and less than 2.0. The adhesion layer may also be made of a mixture of multiple metals or metal oxides.

[0082] The thickness of the adhesive layer is preferably more than 0 nm and not more than 20 nm, particularly preferably 1 nm or more and not more than 10 nm, from the viewpoint of maintaining adhesion between the hard coat film and the optical functional layer and obtaining good optical properties.

[0083] (Optical Functional Layer) The optical functional layer 50A provided in the optical laminate 200A shown in FIG. 13 is a laminate that exhibits anti-reflection function. The optical functional layer 50A is made of an inorganic oxide or an inorganic nitride. The optical functional layer 50A is a laminate of a total of four layers, in which high-refractive-index layers 4 and low-refractive-index layers 5 are alternately stacked in order from the adhesive layer 3 side. In the optical functional layer 50A, the high-refractive-index layer and low-refractive-index layer closest to the transparent substrate 1 are referred to as the first high-refractive-index layer 4a and the first low-refractive-index layer 5a, respectively, and the high-refractive-index layer and low-refractive-index layer farthest from the transparent substrate 1 are referred to as the second high-refractive-index layer 4b and the second low-refractive-index layer 5b, respectively. The number of high-refractive-index layers 4 and low-refractive-index layers 5 is not particularly limited, and the number of high-refractive-index layers 4 and low-refractive-index layers 5 can be any number.

[0084] 13, the optical function layer 50A is made of a laminate in which low refractive index layers 5 and high refractive index layers 4 are alternately stacked, and therefore, light incident from the antifouling layer 6 side interferes with the optical function layer 50A, thereby reducing the intensity of the reflected light and providing an antireflection function. Therefore, an antireflection function is obtained that prevents light incident from the antifouling layer 6 side from being reflected in one direction.

[0085] The low refractive index layer 5 contains, for example, a metal oxide. The low refractive index layer 5 may contain an oxide of Si, such as SiO ２ It is preferable that the layer contains, as a main component, SiO (oxide of Si) or the like. ２ The single layer film is colorless and transparent. In this embodiment, the main component of the low refractive index layer 5 means a component contained in the low refractive index layer 5 at 50% by mass or more. When the low refractive index layer 5 is a layer containing an oxide of Si as a main component, it may contain less than 50% by mass of another element. The content of elements other than the oxide of Si is preferably 10% or less. Examples of other elements that may be contained include Na for improving durability, Zr, Al, or N for improving hardness, and Zr and Al for improving alkali resistance.

[0086] The refractive index of the low refractive index layer 5 is preferably 1.20 to 1.60, more preferably 1.30 to 1.50. The dielectric material used for the low refractive index layer 5 is magnesium fluoride (MgF ２ , refractive index 1.38).

[0087] The refractive index of the high refractive index layer 4 is preferably 2.00 to 2.60, more preferably 2.10 to 2.45. The dielectric material used for the high refractive index layer 4 is niobium pentoxide (Nb ２ O ５ , refractive index 2.33), titanium oxide (TiO ２ , refractive index 2.33 to 2.55), tungsten oxide (WO ３ , refractive index 2.2), cerium oxide (CeO ２ , refractive index 2.2), tantalum pentoxide (Ta ２ O ５ , refractive index 2.16), zinc oxide (ZnO, refractive index 2.1), indium tin oxide (ITO, refractive index 2.06), zirconium oxide (ZrO ２ , refractive index 2.2). When it is desired to impart conductive properties to the high refractive index layer 4, for example, ITO or indium zinc oxide (IZO) can be selected.

[0088] The optical function layer 50A may include, for example, a high refractive index layer 4 made of niobium pentoxide (Nb ２ O ５ , refractive index 2.33), and the low refractive index layer 5 is made of SiO ２ It is preferable to use one consisting of:

[0089] The thickness of the low-refractive index layer 5 may be in the range of 1 nm to 200 nm, and is appropriately selected depending on the wavelength range in which anti-reflection function is required. The thickness of the high-refractive index layer 4 may be, for example, in the range of 1 nm to 200 nm, and is appropriately selected depending on the wavelength range in which anti-reflection function is required. The thicknesses of the high-refractive index layer 4 and the low-refractive index layer 5 can each be appropriately selected depending on the design of the optical function layer 50A. For example, from the adhesive layer 3 side, the high-refractive index layer 4 can be 5 to 50 nm, the low-refractive index layer 5 can be 10 to 80 nm, the high-refractive index layer 4 can be 20 to 200 nm, and the low-refractive index layer 5 can be 50 to 200 nm.

[0090] Of the layers forming the optical functional layer 50A, a low refractive index layer 5 is disposed on the side of the antifouling layer 6. It is preferable that the low refractive index layer 5 of the optical functional layer 50A be in contact with the antifouling layer 6, as this improves the antireflection performance of the optical functional layer 50A.

[0091] (Anti-fouling layer) The anti-fouling layer 6 is formed on the outermost surface of the optical functional layer 50A and prevents the optical functional layer 50A from being soiled or damaged. Furthermore, when the anti-fouling layer 6 is applied to a touch panel or the like, its abrasion resistance suppresses wear of the optical functional layer 50A. The anti-fouling layer 6 of this embodiment is made of a vapor-deposited film formed by vapor-depositing an anti-fouling material. In this embodiment, the anti-fouling layer 6 is formed by vacuum-depositing a fluorine-based organic compound as the anti-fouling material on one surface of the low-refractive index layer 5 that constitutes the optical functional layer 50A. In this embodiment, since the anti-fouling material contains a fluorine-based organic compound, the optical laminate 10 has even better abrasion resistance and alkali resistance.

[0092] A compound comprising a fluorine-modified organic group and a reactive silyl group (e.g., alkoxysilane) is preferably used as the fluorine-based organic compound constituting the antifouling layer 6. Examples of commercially available products include Optool DSX (manufactured by Daikin Corporation) and KY-100 series (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0093] The fluorine-based organic compound constituting the antifouling layer 6 is a compound consisting of a fluorine-modified organic group and a reactive silyl group (for example, alkoxysilane), and the low refractive index layer 5 of the optical function layer 50A in contact with the antifouling layer 6 is made of SiO ２ When a compound consisting of fluorine-based organic compounds is used, the silanol groups in the skeleton of the fluorine-based organic compounds and SiO ２ This results in good adhesion between the optical function layer 50A and the antifouling layer 6, which is preferable.

[0094] The optical thickness of the antifouling layer 6 may be in the range of 1 nm or more and 20 nm or less, and preferably in the range of 3 nm or more and 10 nm or less. When the thickness of the antifouling layer 6 is 1 nm or more, sufficient abrasion resistance can be ensured when the optical laminate 10 is used for touch panels, etc. When the thickness of the antifouling layer 6 is 3 nm or more, the liquid resistance, etc. of the optical laminate 10 is improved. When the thickness of the antifouling layer 6 is 20 nm or less, the time required for vapor deposition is short, allowing for efficient production.

[0095] Fig. 14 is a cross-sectional view of an optical laminate according to a modified example of Fig. 13. The optical laminate 200B shown in Fig. 14 has an optical function layer 50B that is different from the optical function layer 50A provided in the optical laminate 200A. As shown in Fig. 14, the optical laminate 200B may have an optical function layer 50B that is a single layer film of an inorganic oxide or an inorganic nitride. The optical function layer 50B may contain an oxide of Si from the viewpoint of availability and cost. The optical function layer 50B may be made of, for example, SiO ２ It is a single layer film containing SiO (oxide of Si) as the main component. ２ The single layer film is colorless and transparent. In this embodiment, the main component of the optical function layer 50B means a component contained in the optical function layer 50B at 50 mass % or more. The optical function layer 50B is made of SiO ２ It may also be a layer consisting of

[0096] Fig. 15 is a cross-sectional view of an optical laminate according to another modified example of Fig. 13. The optical laminate 200C shown in Fig. 15 includes an adhesion layer 3, an optical functional layer 50A, and an antifouling layer 6 on a hard coat film 100B. Like the optical laminate 200C shown in Fig. 15, the optical laminate according to this embodiment may have a configuration in which the hard coat layer 2X is formed on a hard coat film having a first layer 2a and a second layer 2b.

[0097] In the optical laminate according to this embodiment, another layer may be provided on the surface of the transparent substrate 1 opposite to the side on which the hard coat layer 2, 2X and the optical functional layers 50A, 50B are formed. Examples include an adhesive layer attached to a display and a release layer provided on the adhesive layer. The adhesive layer is a layer that is adhered to a display or the like. The adhesive layer is, for example, an acrylic adhesive, a silicone adhesive, or a urethane adhesive. The release layer is a layer that protects the adhesive layer and is peeled off at the time of lamination, allowing the exposed adhesive layer to be attached. The release layer is, for example, paper or a film coated with a release agent. The adhesive layer may or may not have a separate substrate on the transparent substrate 1 side. That is, the adhesive layer may be formed directly on the transparent substrate 1 or via a substrate. However, from the viewpoint of facilitating handling of the optical laminate and a display to which the optical laminate is attached, it is preferable to have a substrate layer on the transparent substrate 1 side.

[0098] The optical laminate according to this embodiment has high hardness, similar to the hard coat film according to the above embodiment, and when applied to an organic EL display, it is possible to provide an optical laminate with good black brightness.

[0099] Examples of the present invention will be described below, but the present invention is not limited to the following examples.

[0100] <Preparation of Composition for Hard Coat Layer> In order to produce the hard coat films of Examples 1 to 4 and Comparative Examples 1 to 3 below, photocurable resin compositions containing a filler were prepared, except for Comparative Example 1. As shown in Tables 1 and 2, the resin compositions were prepared by dissolving a filler, an acrylate, a leveling agent, and a photopolymerization initiator in a solvent. Table 1 shows the formulation when the entire resin composition including the solvent is taken as 100%. Table 2 shows the formulation without the solvent. In other words, Table 2 shows the formulation when the total solid content is taken as 100%. The percentages in the table represent the blend ratio in the resin composition and represent mass %.

[0101]

[0102]

[0103] Example 1-1 First, an 80 μm thick triacetyl cellulose (TAC) substrate was prepared as the transparent substrate. The resin composition of Example 1 shown in Table 1 was applied to the transparent substrate using a gravure coater so that the thickness of the hard coat layer before curing was 10 μm. The resin composition applied to the transparent substrate was then cured by irradiating it with light, producing a hard coat film as shown in FIG. 9 , in which a hard coat layer was formed on the transparent substrate and comprised a second layer containing the resin components of the transparent substrate and the hard coat layer, and a first layer containing a filler. The filler used in Example 1-1, PGMAC-4130Y (manufactured by Nissan Chemical Industries, Ltd.), is a filler with an average particle size of 42 nm, in which the surfaces of silica particles are modified with (meth)acrylic groups.

[0104] [Example 2-1] A hard coat film was produced in the same manner as in Example 1, except that the resin composition mixed with the filler was changed to that of Example 2 shown in Table 1. In Example 2-1, the thickness of the first layer in the hard coat layer was made thinner than that of Example 1 by changing the solvent for the resin composition.

[0105] Example 3-1 A hard coat film was produced in the same manner as in Example 1, except that the resin composition mixed with the filler was changed to that of Example 3 shown in Table 1. In Example 3-1, the solvent for the resin composition was changed to PGM (propylene glycol monomethyl ether), thereby producing a hard coat film in which a hard coat layer containing a resin and a filler was provided in contact with a transparent substrate as shown in Figure 1. PGMAC-3140Y (manufactured by Nissan Chemical Industries, Ltd.) used as the filler is a filler with an average particle size of 22 nm, in which the surfaces of silica particles are modified with (meth)acrylic groups.

[0106] [Example 4-1] A hard coat film was produced in the same manner as in Example 1, except that the resin composition was changed to that of Example 4 shown in Table 1. In Example 4-1, the thicknesses of the first and second layers of the hard coat layer were adjusted by changing the compounding ratio of the resin composition.

[0107] [Comparative Example 1-1] A hard coat film was produced in the same manner as in Example 1, except that the resin composition was changed to that of Comparative Example 1 shown in Table 1. In Comparative Example 1-1, a hard coat film was produced in which a hard coat layer containing no filler was formed on a transparent substrate using a resin composition containing no filler.

[0108] [Comparative Example 2-1] A hard coat film was produced in the same manner as in Example 1, except that the resin composition was changed to that of Comparative Example 2 shown in Table 1. In Comparative Example 2-1, PGM was used as the solvent to produce a hard coat film in which a hard coat layer having no first layer was formed on a transparent substrate.

[0109] [Comparative Example 3-1] A hard coat film was produced in the same manner as in Example 1, except that the resin composition was changed to that of Comparative Example 3 shown in Table 1. In Comparative Example 3-1, the thickness of the first layer was made thinner and the thickness of the second layer was made thicker by changing the compounding ratio of , and IPA-ST-L (manufactured by Nissan Chemical Industries, Ltd.), i.e., silicon dioxide that was not surface-modified, was used as the filler.

[0110] Furthermore, in Examples 1-2, 2-2, 3-2, and 4-2 and Comparative Examples 1-2, 2-2, and 3-2, optical laminates (anti-reflection films) were produced by forming an adhesion layer, an optical functional layer, and an antifouling layer by the following method on the hard coat film layers produced in Examples 1-1, 2-1, 3-1, and 4-1 and Comparative Examples 1-1, 2-1, and 3-1 above. Examples 1-1 and 1-2 may be collectively referred to as Example 1. Other examples and comparative examples may also be collectively referred to in the same manner.

[0111] <Method of Producing an Anti-Reflection Film> The surface of the hard coat layer was treated by glow discharge treatment at 5 kW. Subsequently, sputtering was performed on the hard coat layer using a Si target and a Nb target as sputtering targets, and a mixture of Ar gas and O ２ The adhesive layer and the optical functional layer were successively formed by reactive sputtering using a mixed gas of Nb and Si. That is, a 3 nm thick adhesive layer made of silicon oxide (SiOx, 0<x<2) which may be oxygen deficient and a 10 nm thick Nb２ O ５ a first high refractive index material layer made of SiO ２ a first low refractive index material layer made of Nb ２ O ５ and a second high refractive index material layer made of SiO ２ and a second low refractive index material layer made of the above material were deposited in this order.

[0112] Next, the pressure in the deposition chamber was 0.01 Pa, the deposition temperature was 230° C., and the retention time was 7.2 s. ２ An antifouling layer having a thickness of 3 nm and made of an alkoxysilane compound having a perfluoropolyether group (KY1903-1, manufactured by Shin-Etsu Chemical Co., Ltd.) was formed on the film by vapor deposition to prepare an optical laminate (anti-reflection film) of the example.

[0113] <Structural Evaluation> The cross section of the hard coat film produced in the above Examples and Comparative Examples was observed with an optical microscope to evaluate the laminate structure. In the observed cross section, the distance from the outermost surface of the filler closest to the transparent substrate was measured and defined as the thickness of the second layer.

[0114] <Evaluation of Black Luminance> The prepared sample was attached to the organic EL display (170 mm x 290 mm) of a notebook PC (ASUS ZenBook 13 OLED) equipped with an organic EL display. A predetermined measurement pattern was displayed on the organic EL display. The settings of the organic EL display were: Brightness setting: MAX, HDR: Enable, Emission angle: 180°, Brightness: 360 cd / m ２Figure 16 shows the measurement pattern displayed on the organic EL display when measuring black luminance in the examples and comparative examples. As shown in Figure 16, the measurement pattern has a checkerboard pattern of white areas W and black areas B. A shielding plate was provided on the hard coat film to cover the entire organic EL display except for the black area B where the measurement area Ra is located. The black area B where the measurement area Ra is located is exposed through an opening in the shielding plate. The black area B where the measurement area Ra is located measures 80 mm x 100 mm, and the measurement area is located at its center of gravity. Measurements were performed at a measurement angle of 2° using a spectroradiometer (TOPCON SR-UL1R) placed 60 cm away from the organic EL display. The measurement conditions met the VESA True Black measurement standard. Black luminance measurements were performed for both the case where the hard coat film was applied to the organic EL display and the case where the anti-reflection film was applied to the organic EL display.

[0115] <Pencil Hardness> The pencil hardness of the prepared hard coat film and anti-reflection film was measured by a method in accordance with JIS K5600-5-4.

[0116] <Haze Value> The haze value of the prepared hard coat film was measured by a method in accordance with JIS-K-7136.

[0117]

[0118] In Table 3, the total thickness of the hard coat layer represents the total thickness of the hard coat layer before curing. The thickness of the second layer, the density of the first layer, the black brightness, the pencil hardness, and the haze values ​​are the average values ​​of the three samples prepared. The filler concentration in Table 3 is the mass % of the filler in the hard coat layer.

[0119] Furthermore, it was confirmed that hard coat films in which the filler particle size was in the range of 30 nm or more and 50 nm or less and the filler concentration in the first layer containing the filler was in the range of 25% to 65%, as in Examples 1 and 2, exhibited low black luminance. Furthermore, it was confirmed that hard coat films in which the filler particle size was in the range of 30 nm or less and the filler concentration in the first layer containing the filler or in the homogeneous hard coat layer was in the range of 25% to 65%, as in Examples 3 and 4, exhibited low black luminance. Furthermore, Examples 1 to 4 exhibited high pencil hardness, achieving both high hardness and the VESA standard of "True Black." In particular, in Examples 1 to 4, the measurement results for black luminance when the hard coat film was applied were 3.5 x 10 －４ (cd / m ２ ) and in Examples 1, 3 and 4, it was less than 3.0 × 10 －４ (cd / m ２ ) and in Example 4, it was less than 2.0 × 10 －４ (cd / m ２ ) in all of Examples 1 to 4. －４ (cd / m ２ ) or less.

[0120] In contrast, in a hard coat film in which the hard coat layer does not contain a filler as in Comparative Example 1, the absence of a filler results in no scattering effect from the filler, and therefore the black brightness is low, but the pencil hardness is also low. Also, in Comparative Example 2 in which the particle size of the filler is 42 nm and the filler concentration in the 10 μm-thick hard coat layer without a second layer is 31.54%, the black brightness was insufficient.

[0121] Furthermore, Comparative Example 3, which used a filler that was not surface-modified with (meth)acrylic groups, exhibited significantly higher black luminance than Example 2, which was the same except for whether the filler was surface-modified or not. This is thought to be because the surface of the filler was not surface-modified with (meth)acrylic groups, and the filler particles aggregated together, increasing the pseudo particle size, and the aggregated particles locally increased scattered light.

[0122] [Examples 5 to 7, Comparative Example 4] Based on the formulations shown in Table 4, hard coat films described in Examples 5 to 7 and Comparative Example 4 were prepared. The resin composition was applied to a transparent substrate, TAC, using a gravure coater to a thickness of 10 μm and cured by irradiating with light to prepare a hard coat film as shown in FIG. 1. The filler concentration in the hard coat layer of Example 5 corresponds to the data for a filler distance of approximately 75 nm in the simulation of FIG. 8. The filler concentration in the hard coat layer of Example 6 corresponds to the data for a filler distance of 120 nm in the simulation of FIG. 8. The filler concentration in the hard coat layer of Example 7 corresponds to the data for a filler distance of approximately 55 nm in the simulation of FIG. 8. The filler concentration in the hard coat layer of Comparative Example 4 was 0%, and the filler distance in the simulation of FIG. 8 was treated as infinite.

[0123]

[0124] (Brightness Evaluation) For Examples 5 to 7 and Comparative Example 4, data corresponding to the simulation conditions shown in the graph in Fig. 8 were actually measured. That is, the brightness of the hard-coated film was measured using the same shielding plate and spectroradiometer as those used to measure the black brightness in the above examples. The brightness was measured through the opening of the shielding plate using the spectroradiometer installed 60 cm away from the hard-coated film.

[0125] 17 is a graph showing the results of the filler concentration and luminance for Examples 5 to 7 and Comparative Example 4. As shown in FIG. 17 , when Examples 5 and 7 have the same filler concentration, Example 7 exhibits lower luminance, while Example 6, whose filler concentration is between Example 7 and Comparative Example 4, exhibits higher luminance than Example 5 and Comparative Example 4, suggesting the presence of a maximum value. In this way, a correlation was confirmed between the simulation results in FIG. 8 and the graph based on the actual measured values ​​in FIG. 17 , confirming the validity of the simulation results in FIG. 8 .

[0126] REFERENCE SIGNS LIST 1 transparent substrate 2, 2X hard coat layer 2a first layer 2b second layer 3 adhesion layer 4 high refractive index layer 4a first high refractive index layer 4b second high refractive index layer 5 low refractive index layer 5a first low refractive index layer 5b second low refractive index layer 6 antifouling layer 10 optical laminate 21 filler 22 resin 30 shielding plate 40 spectroradiometer 50A, 50B optical function layer 100A, 100B hard coat film 200A optical laminate 200B optical laminate 200C optical laminate

Claims

1. A transparent substrate and a hard coat layer formed on the transparent substrate, the hard coat layer containing a filler, and a black luminance measured under the following conditions is 5.0×10 －４ cd / m ２ (Conditions: light emission angle 180 degrees, brightness 360 cd / m ２ A hard coat film is placed in close contact with the organic EL display of the above-mentioned embodiment, white and black areas are displayed in a checkered pattern on the organic EL display, a shielding plate is placed so as to cover the surface of the organic EL display excluding the black areas, and the black luminance in the black areas is measured using a spectroradiometer placed 60 cm away from the organic EL display.

2. The hard coat film according to claim 1, wherein the hard coat layer contains an acrylic resin, the particle size of the filler is 20 nm or more and 50 nm or less, and the surface of the filler is modified with a (meth)acrylic group.

3. The hard coat film according to claim 1, wherein the hard coat layer comprises a first layer separated from the transparent substrate and containing the filler, and a second layer provided between the transparent substrate and the first layer, and the second layer contains a resin component of the transparent substrate and a resin component of the first layer.

4. The hard coat film according to claim 3, wherein the average particle size of the filler is 20 nm or more and 50 nm or less, and the concentration of the filler in the first layer is 25% or more and 65% or less.

5. The hard coat film according to claim 1, wherein the average particle size of the filler is 20 nm or more and 50 nm or less, and the concentration of the filler in the hard coat layer is 40% or more and 65% or less.

6. An optical laminate comprising the hard coat film according to any one of claims 1 to 5 and an optical functional layer formed on the hard coat layer, the optical functional layer being made of an inorganic oxide or an inorganic nitride.

7. The optical functional layer is made of SiO ２ The optical laminate according to claim 6, which is a single layer film consisting of:

8. The optical laminate according to claim 6, further comprising an adhesive layer formed between the hard coat layer and the optical functional layer and in contact with the hard coat layer and the optical functional layer, the optical functional layer being formed by alternately laminating high refractive index material layers and low refractive index layers, and the adhesive layer being in contact with the high refractive index material layer.

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