Hard coat film and optical laminate

Abstract

To provide a hard coat film having high hardness and excellent black luminance when applied to an organic EL display, and an optical laminate.SOLUTION: A hard coat film includes a transparent substrate and a hard coat layer formed on the transparent substrate, where the hard coat layer contains a filler and has black luminance of less than 5.0×10-4 cd / m2 as measured under the following conditions (Conditions: the hard coat film is provided in close contact with an organic EL display having a light emission angle of 180 degrees and luminance of 360 cd / m2, a white area and a black area are displayed in a checkerboard pattern on the organic EL display, a shielding plate is provided to cover a surface of the organic EL display excluding the black area, and the black luminance in the black area is measured using a spectroradiometer provided 60 cm away from the organic EL display).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a hard coat film and an optical laminate.

Background Art

[0002] In a display, surface defects caused by scratches and fingerprints lead to a decrease in the visibility of the display. Therefore, a hard coat film is often applied to the surface of the display from the viewpoint of suppressing surface defects. With the touch panelization of various operating devices having a display, the importance of the hard coat film has increased, and it is said that the pencil hardness of the entire film formed on the display needs to be 3H or more. As a hard coat film, one in which a filler is dispersed to improve the hardness is known.

[0003] In recent years, as a display, the spread of organic EL displays has been progressing. Since organic EL utilizes the self-luminescence of each pixel, it does not require a backlight unlike a liquid crystal display in which liquid crystal pixels are illuminated by a backlight provided behind the liquid crystal pixels.

[0004] In a liquid crystal display, when expressing black, the liquid crystal pixels are set to black display, that is, the light from the backlight is blocked. However, only by the optical rotation characteristics of the liquid crystal molecules, it is not always possible to block the light from the backlight, and some light may leak, resulting in poor luminance (black luminance) in the black region. Therefore, a method of eliminating the leaked light by the phase difference using a polarizing plate or a material with low retardation for a liquid crystal display is known (for example, Patent Document 1).

[0005] On the other hand, in the case of an organic EL, since each pixel can emit light spontaneously to represent black, it is known that the black luminance is good. In recent years, further improvement in contrast in organic EL displays has been demanded. For improving contrast, improvement in black luminance is important. It is considered that the key factors for improving black luminance depend on the materials and structures of the organic EL display and the film applied to the organic EL display.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] When a hard coat film in which fillers are dispersed is applied to an organic EL display, light in the light-emitting region adjacent to the black region may leak into the black region, resulting in an increase in black luminance. Even when using a polarizing plate or a material with low retardation as disclosed in Patent Document 1 for the organic EL display, it was not effective in countermeasures for black luminance. Also, a hard coat film in which fillers are dispersed and which can achieve black luminance conforming to the VESA DisplayHDR500 True Black certification has not been known. Therefore, when applying a hard coat film in which fillers are dispersed to an organic EL display, other methods for improving black luminance are necessary.

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

Means for Solving the Problems

[0009] The present invention provides the following means for solving the above problems.

[0010] (1) The hard coat film according to one aspect of the present invention includes a transparent substrate and a hard coat layer formed on the transparent substrate. The hard coat layer contains a filler, and the black luminance measured under the following conditions is less than 5.0×10 -4 cd / m 2 . (Condition: A hard coat film is provided in close contact with an organic EL display having a light emission angle of 180 degrees and a luminance of 360 cd / m 2 . The organic EL display displays white regions and black regions in a checkerboard pattern. A shielding plate is provided so as to cover the surface of the organic EL display except for the black region. The black luminance in the black region is measured with a spectro-radiometer provided 60 cm away from the organic EL display.)

[0011] (2) In the hard coat film of (1) above, 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 may be modified with a (meth)acrylic group.

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

[0013] (4) In the hard coat film of (3) above, 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 may be 25% or more and 65% or less.

[0014] (5) In the hard coat film of (1) or (2) above, 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 may be 40% or more and 65% or less.

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

[0016] (7) In the optical laminate of (6) above, the optical functional layer may be a single-layer film made of SiO 2 and the like.

[0017] (8) The optical laminate of (6) or (7) above further includes an adhesion 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 has a high refractive index material layer and a low refractive index layer alternately laminated, and the adhesion layer may be in contact with the high refractive index material layer.

Advantages of the Invention

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

Brief Description of the Drawings

[0019]

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Best Mode for Carrying Out the Invention

[0020] Hereinafter, this embodiment will be described in detail with appropriate reference to the drawings. The drawings used in the following description may show, for the sake of convenience, the characteristic parts enlarged in order to make the features of the present invention easier to understand, and the dimensional ratios of each component may be different from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto, and it can be appropriately modified and implemented within the range in which the effects are achieved.

[0021] [Hard Coat Film] FIG. 1 is a cross-sectional view of a hard coat film according to an embodiment of the present invention. The hard coat film 100A shown in FIG. 1 includes 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, and the black luminance measured under the following conditions is 5.0×10 -4 cd / m 2 or less. (Measurement conditions for black luminance: A hard coat film is provided on an organic EL display with a light emission angle of 180 degrees and a luminance of 360 cd / m 2 , and the black luminance is measured with a spectro-radiometer provided 60 cm away from the organic EL display.) Details of the measurement conditions for black luminance will be described later.

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

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

[0024] In addition, the "transparent material" referred to in the present invention means a material having a light transmittance of 80% or more in the used wavelength range as long as the effects of the present invention are not impaired. In addition, in the present embodiment, "(meth)acrylic" means methacrylic and acrylic.

[0025] As long as the optical properties are not significantly impaired, the transparent substrate 1 may contain a reinforcing material. The reinforcing material is, for example, cellulose nanofibers, nanosilica, etc. In particular, polyester resins, acetate resins, polycarbonate resins, polyolefin resins are preferably used as the reinforcing material. Specifically, a triacetyl cellulose (TAC) substrate is preferably used as the reinforcing material. In addition, a glass film, which is an inorganic substrate, can also be used for the transparent substrate 1.

[0026] The transparent substrate 1 may be a film provided with an optical function and / or a physical function. Examples of the film having an optical and / or physical function include a polarizing plate, a retardation compensation film, a heat ray blocking film, a transparent conductive film, a brightness enhancing film, a barrier property enhancing film, and the like.

[0027] The thickness of the transparent substrate 1 is not particularly limited, but for example, it is preferably 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. Further, when the thickness of the transparent substrate 1 is 25 μm or more, even if the hard coat layer 2 is continuously formed on the transparent substrate 1, wrinkles are less likely to occur and there are few manufacturing concerns, which is preferable. When the thickness of the transparent substrate 1 is 40 μm or more, wrinkles are even less likely to occur, which is preferable.

[0028] During manufacturing, when 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, it is easy to wind the optical laminate 10 during manufacturing and the optical laminate 10 after manufacturing in a roll shape, and the optical laminate 10 can be manufactured efficiently. Further, 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 manufactured more efficiently, and further thinning and weight reduction are possible, which is preferable.

[0029] The transparent substrate 1 may be previously subjected to an etching treatment such as sputtering, corona discharge, ultraviolet irradiation, electron beam irradiation, chemical conversion, oxidation, etc. and / or an undercoat treatment on the surface. By performing these treatments in advance, the adhesion with the hard coat layer 2 formed on the transparent substrate 1 can be improved. Further, before forming the hard coat layer 2 on the transparent substrate 1, if necessary, the surface of the transparent substrate 1 is preferably dust-removed and cleaned by performing solvent cleaning, ultrasonic cleaning, etc. on the surface of the transparent substrate 1.

[0030] (Hard coat layer) The hard coat layer 2 contains a binder resin 22 and a filler 21 as essential components, and may contain other components such as a dispersant as optional components. As the binder resin 22, known materials can be used. The filler 21 is contained in the binder resin within a range that does not impair transparency. As the filler 21, an organic material, an inorganic material, or a material composed of an organic material and an inorganic material may be used. However, from the viewpoints of hardness and flexural resistance, an inorganic material is preferable, and silica particles composed of silica are more preferable. Further, from the viewpoint of suppressing aggregation of the filler 21 and locally increasing the scattered light due to the filler 21, silica particles with surface modification are particularly preferable because they have good dispersibility in the binder resin.

[0031] As the binder resin used for the hard coat layer 2, a transparent resin is preferable. For example, an ionizing radiation curable resin that is a resin cured by ultraviolet rays or electron beams, a thermoplastic resin, a thermosetting resin, etc. can be used.

[0032] Examples of the ionizing radiation curable resin used for the binder resin of the hard coat layer 2 include ethyl (meth)acrylate, ethylhexyl (meth)acrylate, styrene, methylstyrene, N-vinylpyrrolidone, and the like. In addition, examples of the compound which 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 tetra(meth)acrylate, dipentaerythritol 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, ditrimethylolpropane tetra(meth)acrylate and other polyfunctional compounds. Among them, pentaerythritol triacrylate (PETA), dipentaerythritol hexaacrylate (DPHA) and pentaerythritol tetraacrylate (PETTA) are preferably used. Note that “(meth)acrylate” refers to methacrylate and acrylate. Further, as the ionizing radiation curable resin, those obtained by modifying the above-described compounds with PO (propylene oxide), EO (ethylene oxide), CL (caprolactone) or the like can also be used. In addition, urethane (meth)acrylate oligomer, epoxy (meth)acrylate oligomer and the like can also be used from the viewpoint of film formation and viscoelasticity adjustment of the hard coat layer.

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

[0034] The hard coat layer 2 contains, for example, a binder resin 22 and silica particles as the filler 21. As described above, the silica particles preferably include 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. Specific examples of the silane compound 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, mercapto group-containing silane compounds, etc. These may be used alone or in combination of multiple types. The silane compound is appropriately selected according to the type of the binder resin. When the binder resin contains a functional group, a silane compound having the same functional group as the binder resin is preferable. For example, when the binder resin contains a (meth)acrylate compound as a 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 the surface modification preferably has an alkoxysilyl group or a silanol group at the end because the bonding with the hydroxyl groups present on the silica particle surface is good. Due to the prior surface modification of the silica particles, the dispersibility in the binder resin 22 is improved, and by the reaction between the surface treatment agent used for the surface modification and the binder resin, it binds more firmly to the binder resin 22, resulting in improved hardness.

[0035] 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 it also depends on the concentration in the hard coat layer 2. Further, from the viewpoint of suppressing unevenness in appearance for optical use, the average particle size of the filler 21 is preferably 50 nm or less. 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-type hard coat film. Also, considering the appearance and optical characteristics of the display, the haze value is preferably 1% or less, and by having the average particle size of the filler 21 within the above range, it is possible to achieve such a haze value. Specifically, when the haze value is low, the contrast is suppressed.

[0036] The concentration of the filler 21 in the hard coat layer 2 is, for example, more than 0% and 80% or less. As will be described in detail later, the black luminance depends on the concentration (inter-particle distance) of the filler 21 in the hard coat layer 2, which is the region where the filler 21 exists in the hard coat film 100A, and the particle size of the filler 21. 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. Also, 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, it 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 preferred.

[0037] As a filler contained in the hard coat layer 2, in order to impart toughness to the hard coat layer 2, various reinforcing materials can be used within a range that does not impair the optical properties. Examples of the reinforcing material include cellulose nanofibers.

[0038] 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 can be obtained, making it difficult for scratches during manufacturing to occur. Also, when the thickness of the hard coat layer 2 is 100 μm or less, it becomes possible to thin and lighten the hard coat film 100A. Further, 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 bends during manufacturing are less likely to occur, and productivity is good.

[0039] The hard coat layer 2 may be a single layer or may be a laminate of multiple layers. Also, when the hard coat layer 2 is a laminate of multiple layers, the filler may be dispersed in each layer, or may be contained only in the layer on the side away from the transparent substrate 1. Further, the hard coat layer 2 may be further provided with known functions such as ultraviolet absorption performance, antistatic performance, refractive index adjustment function, hardness adjustment function, etc. Also, the functions imparted to the hard coat layer 2 may be imparted in a single hard coat layer or may be divided and imparted to multiple layers.

[0040] According to the hard coat film 100A according to the above embodiment, it exhibits a high hardness exceeding a pencil hardness of 3H, and the black luminance is good when applied to an organic EL display. That is, in the region where the non-emitting pixels are located (black region) adjacent to the region where the pixels that emit light in the organic EL display are located, it is possible to suppress the leakage of light from each emitting pixel due to interface reflection or scattering and the increase in black luminance.

[0041] Hereinafter, with reference to the drawings as appropriate, the operation of the hard coat film shown in FIG. 1 will be described. FIGS. 2 and 3 are diagrams for explaining the interface reflection when the hard coat film is applied to an organic EL display. In FIGS. 2 and 3, as an example, the hard coat film 100A shown in FIG. 1 is formed on the organic EL display OLED, a shielding plate 30 having an opening is formed on the hard coat film 100A, and the brightness (black brightness) in the black region of the organic EL display OLED is measured by a spectro-radiometer 40 through the opening. However, the filler 21 is omitted for simplification of the explanation of the interface reflection. Further, in FIGS. 2 and 3, the hard coat film 100A is shown separated from the organic EL display OLED and the shielding plate 30 for convenience of explanation, but the hard coat film 100A is in contact with the organic EL display OLED and the shielding plate 30. Hereinafter, consider the case where the distance between the spectro-radiometer 40 and the organic EL display OLED in the plane normal direction of the organic EL display OLED is 60 cm (measurement angle 2°), and the distance between the white region W in the in-plane direction of the organic EL display OLED and the spectro-radiometer 40 is 50 mm.

[0042] As shown in FIG. 2, in the organic EL display OLED, when the white region W and the black region B are displayed in a checkered pattern by dividing each pixel into a region that emits light and a region that does not emit light, the light L emitted from the white region W is interface-reflected many times within the hard coat film 100A. Each time of interface reflection, the energy of the photon is lost, and the energy of the light detected by the spectro-radiometer 40 becomes a small value.

[0043] As shown in FIG. 3, part of the light L emitted from the white region W directly passes through the hard coat film 100A as direct transmitted light, and part of it is specularly reflected to become internally reflected light. Compared with the example shown in FIG. 2, only a small number of specular reflections occur and the light passes through the opening of the shielding plate 30. However, because the angle is large, this light is not detected as a signal by the spectro-radiometer 40. In FIGS. 2 and 3, since the distance between the organic EL display OLED and the spectro-radiometer 40 in the plane direction of the organic EL display OLED is large compared to the distance between the white region W and the spectro-radiometer 40 in the plane direction of the organic EL display OLED, it is considered that the influence of the light emitted from the white region W and specularly reflected on the black region B is small.

[0044] Next, the influence of scattering by the filler when the filler is contained in the hard coat film will be described with reference to FIGS. 4 to 6. FIGS. 4 to 6 are diagrams for explaining scattering when a hard coat film containing a filler is applied to an organic EL display. In FIGS. 4 to 6, as an example, the hard coat film 100A shown in FIG. 1 is formed on the organic EL display OLED, the shielding plate 30 is formed on the hard coat film 100A, and the spectro-radiometer 40 measures the luminance (black luminance) in the black region of the organic EL display OLED. However, only one filler 21 is shown for simplicity in the explanation of the scattering by the filler 21, and the scattering by the filler 21 will be described.

[0045] As shown in FIG. 4, when the filler 21 is located above the white region W, the light L emitted from the white region W is scattered when it reaches the filler 21. When the particle size of the filler 21 is about 50 nm or less, Rayleigh scattering of visible light occurs, and FIG. 4 shows the state in which the scattered light spreads concentrically. Due to the positional relationship between the opening in the shielding plate 30 and the spectro-radiometer 40, the light scattered above the white region W is not detected as a signal by the spectro-radiometer 40.

[0046] 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 greatly depends on the particle size. For example, at a refractive index of 1.5, a wavelength of 780 nm, and a particle size of 42 nm, the scattered light I of one particle is 0 1.3×10 -7 times that of the incident light I, and most of the incident light does not become scattered light but travels straight (becomes transmitted light).

[0047] [Number] (In formula (1), I 0 : incident light, R: particle distance, λ: light wavelength, n: refractive index of space, d: particle size)

[0048] As shown in FIG. 5, when the filler 21 is positioned directly below the spectro-radiometer 40, when the light L emitted at an angle from the white region W directly reaches the filler 21, it is detected as a signal by the spectro-radiometer 40 through the aperture. That is, the scattered light by such a filler 21 leads to an increase in black luminance.

[0049] As shown in FIG. 6, consider the light L emitted at a smaller angle from the white region W when the filler 21 is positioned directly below the spectro-radiometer 40 compared to the example shown in FIG. 5. The light L is specularly reflected at the interface in the hard coat film 100A, and each time of specular reflection, the energy of the photon is lost based on the same principle as the case shown in FIG. 3. However, when it reaches the filler 21, scattering occurs, and the scattered light is detected as a signal by the spectro-radiometer 40. That is, the scattered light by such a filler 21 leads to an increase in black luminance.

[0050] As described with reference to FIGS. 2 to 6, the black luminance becomes high due to the scattering of the filler 21 located directly below the spectro-radiometer 40. The scattered light by the filler becomes larger as the particle size of the filler is larger. However, when a large number of fillers are contained in the hard coat film such as the hard coat film 100A, the light emitted from the white region W is extremely unlikely to directly reach the filler 21 located directly below the spectro-radiometer 40 without being affected by other fillers 21, and it is necessary to consider the influence of the plurality of fillers 21. That is, it is necessary to consider the value of (1 + cos 2 θ) / 2R 2 in the above Rayleigh scattering formula (formula (1)).

[0051] FIG. 7 is a diagram for explaining the black luminance measured when the hard coat film of FIG. 1 is applied to an organic EL display. The spectro-radiometer 40 detects, as a signal, the scattered light by the filler 21 located in the measurement region Ra directly below it in the hard coat layer 2, and does not directly detect the scattered light by the filler 21 located in the intermediate region Rb located in the in-plane direction of the measurement region Ra as a signal.

[0052] On the other hand, as shown in FIG. 7, in the hard coat film 100A containing a large number of fillers, the scattered light of the filler 21 located in the intermediate region Rb reaches the filler 21 located in the measurement region Ra and is scattered to be detected as a signal (scattered luminance signal). Further, the light reaching the filler 21 located in the intermediate region Rb includes the light emitted directly from the white region W and reaching the filler, the light reaching the filler through the interface reflection, and the scattered light from other fillers. Among these, the light other than the light emitted directly from the white region W and reaching the filler loses the energy of photons due to scattering or interface reflection. The scattering loss, which is the loss due to scattering in the intermediate region Rb, becomes larger as the concentration of the filler 21 is higher, and also becomes larger as the particle size of the filler 21 is larger.

[0053] On the other hand, as described above, the black luminance increases due to the influence of the scattered light by the filler 21 in the measurement region Ra. Focusing on the measurement region Ra, the scattered light of the filler 21 in the measurement region Ra that affects the black luminance is larger as the particle size of the filler 21 is larger and larger as the concentration of the filler 21 is higher. Therefore, it has been found that it is important to optimize the particle size and concentration of the filler 21 in the hard coat layer 2 in order to have high hardness and low black luminance.

[0054] Summarizing these, under the measurement conditions of the present invention, attention is paid to the leakage light from the white region W to the black region B, and the evaluation is made by shielding the direct light from the white region W. The light reaching the measurement region Ra in front of the black region B is reflected and scattered inside the hard coat film 100A. The light emission angle of the organic EL display OLED is wide (about 180°), and light enters the hard coat film at various angles. Light with a small incident angle reaches the front of the black region, so the number of interface reflections is large and the signal becomes extremely weak. Light with a large incident angle is transmitted to the measurement region Ra in front of the black region B mainly by the scattering of the filler 21 distributed in the hard coat layer 2.

[0055] The generation of electric dipoles is the main cause of scattering, or the ease of generation is closely related to the particle size. Particles that are sufficiently small compared to the wavelength are subject to Rayleigh scattering, and large particles are subject to Mie scattering. From the viewpoint of no occurrence of unevenness in appearance in optical applications, the particle size is preferably 50 nm or less, and the scattering at this particle size is generally classified as Rayleigh scattering. In that case, the scattered light of one particle is related to the refractive index of the substance and the particle size. Since the refractive index of the resin 22 in the hard coat layer 2 does not change significantly, basically, the larger the particle size of the filler 21, the stronger the scattered light.

[0056] For the incident light, the scattered light of a single filler 21 is very small, and most of the light is transmitted without scattering. The light reaching the black region B has a close relationship with the optical path length and the filler concentration in the region where the filler 21 exists. In particular, since the filler concentration is related to the probability of generating scattering, it is a factor that determines the final scattering intensity. Here, the optical path length is the average value of the length transmitted into the hard coat film from the white region to the black region. The scattering occurring in the optical path becomes a loss and weakens the transmitted light. The transmitted light reaches the front of the black region (measurement area Ra), and the light scattered in this area becomes a luminance signal, deteriorating True black. When the filler blending concentration is high, the scattering intensity is strong, the transmitted light is weak, but the scattered luminance signal is strong. Therefore, there may be an extreme value in the luminance of the black region depending on the filler concentration. The relationship between the particle size and the scattering intensity has already been described, and the relationship with the optical path length is, for example, the reason that the leakage light of the black region close to the white region is strong and the leakage light of the black region far away is weak

[0057] The inventors conducted simulations to explore the correlation between the filler concentration (inter-particle distance), filler particle size, and black luminance in the hard coat layer 2

[0058] FIG. 8 is a graph obtained by simulating the correlation between the approximate luminance and the inter-particle distance of the filler when light is incident in the in-plane direction from the side 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 is obtained by forming a shielding plate with an opening on the hard coat film, the opening being provided at a position approximately 50 nm in the in-plane direction from the end of the hard coat film, and simulating the luminance measured by a spectro-radiometer provided 60 cm away from the hard coat film through the opening. Also, the incident light is assumed to be the case where light with a luminance of 360 cd / m 2 is introduced 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 of those with a particle size of 22 nm, the result with a filler distance of 22 nm is the result of the condition where the fillers in the hard coat layer 2 are in contact with each other. Incidentally, although the simulation results shown in FIG. 8 consider Rayleigh scattering by the fillers, since they are simulation results that do not consider scattering by the resin contained in the hard coat layer 2 and scattering by the transparent substrate, it is considered that the black luminance when measured under each condition takes a value higher than the value of the approximate luminance in FIG. 8. As the rising value, when using an 80-μm TAC film as the substrate, it rises by about 2.2×10 -4 cd / m 2 or so.

[0059] As shown in FIG. 8, in the hard coat film containing fillers with a particle size of 22 nm, the graph of the approximate luminance with respect to the filler distance does not have a maximum value. That is, the larger the filler distance and the lower the concentration of the fillers 21 in the hard coat layer 2, the lower the approximate luminance. On the other hand, in the hard coat films containing fillers with a particle size of 42 nm and 80 nm, a maximum value is confirmed. That is, when the filler is larger than a predetermined value, as the filler distance increases up to a predetermined value and the concentration decreases, the black luminance increases, and when the filler distance exceeds the predetermined value and the concentration decreases as it increases, the black luminance decreases. The maximum value in the simulation results is considered to be due to the correlation between the magnitude of the scattering loss in the intermediate region Rb and the magnitude of the scattered light with respect to the light reaching the fillers in the measurement region Ra. Also, the filler distance at which the maximum value is taken is considered to depend on the particle size of the filler, the optical path length which is the average value of the length transmitted from the white region W to the black region B in the hard coat film, and the thickness of the layer in which the fillers are distributed.

[0060] Although it is difficult to precisely show the relationship between particle concentration and inter-particle distance, considering the influence of particle diameter and filler distance on luminance, in a hard coat film in which filler 21 with an average particle diameter of less than 30 nm is contained in hard coat layer 2, the concentration of filler 21 in hard coat layer 2 is preferably set to a concentration such that the filler distance becomes 25 nm or more. As a result of simulation, the concentration at this time was 44.5% or less in hard coat layer 2. In a hard coat film in which filler 21 with an average particle diameter of 30 nm or more and 50 nm or less is contained in hard coat layer 2, the filler concentration in hard coat layer 2 is preferably a concentration such that the filler distance becomes 45 nm to 60 nm and a concentration of 280 nm or more. The concentration at this time was 35% or more and 60% or less as the simulation value in the former case. Also, the concentration of 280 nm or more was 0.3% or less as the simulation value. However, the concentration calculated by simulation is finally the filler concentration in hard coat layer 2, not the concentration at the time of compounding including the solvent.

[0061] FIG. 9 is a cross-sectional view of a hard coat film according to a modified example of FIG. 1. The hard coat film 100B shown in FIG. 9 has a hard coat layer 2X separated from the transparent substrate 1, a first layer 2a containing 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.

[0062] 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. The boundary between the first layer 2a and the second layer 2b is parallel to the transparent substrate 1 and is the surface where the filler 21 closest to the transparent substrate 1 is located. Specifically, the end on the transparent substrate 1 side of the filler 21 closest to the transparent substrate 1 can be used as a reference.

[0063] 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 diameter 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%, and preferably 25% to 65%. When the average particle diameter of the filler 21 is 30 nm to 50 nm, the filler concentration in the first layer of the hard coat layer 2X is, for example, 10% to 80%, and preferably 25% to 65%.

[0064] The hard coat layer 2X is configured to have a first layer 2a containing the filler 21 and a second layer 2b provided between the transparent substrate 1 and the first layer 2a, and the second layer 2b contains the same resin component as the resin component of the transparent substrate 1 and the resin component contained in the first layer 2a, depending on the selection of the resin composition used when forming the hard coat layer and the transparent substrate 1. The resin contained in the second layer 2b is not particularly limited, and may be simply a mixture (compatible) of the resin constituting the transparent substrate 1 and the resin contained in the hard coat layer 2X. Further, the resin contained in the second layer 2b may be such that at least one of the resin constituting the transparent substrate 1 and the resin contained in the first layer 2a has undergone a chemical change by heating, light irradiation, or the like.

[0065] As a method for forming the second layer 2b, when forming the hard coat layer 2X on the transparent substrate 1, a method can be mentioned in which a solvent for dissolving / dispersing the constituent resin is a substance having solubility in the transparent substrate 1. As the transparent substrate 1, any one selected from the group consisting of triacetyl cellulose (TAC), polyethylene terephthalate, polycarbonate, and acrylic is selected, and as the resin composition used when forming the hard coat layer, a composition containing propylene glycol monomethyl ether acetate (PGMAC), butyl acetate, cyclohexanone (ANON), etc. in the solvent is selected, so that the transparent substrate 1 is dissolved, and a configuration in which the hard coat layer 2X as shown in FIG. 9 has the second layer 2b between the first layer 2a and the transparent substrate 1 can be realized. When the hard coat layer 2 as shown in FIG. 1 contains the resin 22 and the filler 21, that is, when it has a configuration consisting of the first layer, the above materials are not used for the solvent when producing the hard coat layer, and a resin composition in which the solvent is composed of propylene glycol monomethyl ether (PGM), etc. may be used. The solvent is appropriately selected in consideration of the type of the transparent substrate 1 to be used and its solubility.

[0066] When the resin composition containing the solvent for dissolving the transparent substrate 1 as described above is applied and irradiated with light including UV to be cured, a penetration layer (second layer) containing the components of the binder resin 22 constituting the hard coat layer 2X and the resin components of the transparent substrate 1 is formed on one surface of the transparent substrate. Due to the dissolution of the hard coat layer 2X by the solvent and the penetration of the resin components, the thickness of the transparent substrate 1 becomes slightly smaller.

[0067] By selecting a material such that the second layer 2b is formed, while maintaining the total thickness of the transparent substrate 1 and the hard coat layer 2X to a desired design, the configuration of the first layer 2a, which is the region where the filler 21 exists, is adjusted to obtain desired optical characteristics. The thicknesses of the first layer 2a and the second layer 2b can be adjusted by the type and amount of the above solvent. As a result of forming the penetration layer in this way, the adhesion between the transparent substrate 1 and the hard coat layer 2 becomes good, and the generation of interference fringes due to the refractive index difference between the layers can be suppressed.

[0068] FIG. 10(a) is a diagram for explaining 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 for explaining the black luminance measured when the hard coat film of FIG. 9 is applied to an organic EL display.

[0069] The content of the filler 21 in the hard coat layer 2 in the hard coat film 100A shown in FIG. 10(a) and the content of the filler 21 in the hard coat film 100B shown in FIG. 10(b) are the same. On the other hand, in the first layer 2a of FIG. 10(b), the filler concentration is higher than that in the hard coat layer 2 of FIG. 10(a), which is the region where the filler 21 exists. Specifically, the filler concentration has increased by {(the thickness of the hard coat layer 2) / (the thickness of the first layer 2a)} times. Along with this, the filler concentration in the measurement region Ra measured by the spectro-radiometer 40 has also increased at the same magnification as above. Therefore, the transmitted light in the intermediate region Rb changes so as to decrease, and in the hard coat film 100B, it is possible to change the optical characteristics without changing the total thickness of the transparent base material and the hard coat layer.

[0070] FIG. 11 is a graph obtained by simulating the correlation between the estimated luminance and the inter-particle distance of the filler when light is incident in the in-plane direction from the side on the hard coat films 100A and 100B containing the filler with an average particle diameter of 42 nm. The simulation in FIG. 11 uses a shielding plate with the same aperture as the simulation in FIG. 8 and a spectro-radiometer, and simulates the luminance of the light detected through the aperture when the light incident from the side of the hard coat film. FIG. 11 shows graphs of a hard coat film in which a hard coat layer is formed of a similar material and has a uniform structure with a thickness of 10 μm 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, respectively, in relation to a transparent substrate. That is, under the condition that the filler distance is the same, the filler concentration in the latter first layer is 1.67 times that in the former hard coat layer.

[0071] FIG. 12 is a graph simulating the correlation between the estimated luminance and the inter-particle distance of the filler when light is incident in the in-plane direction from the side on the hard coat films 100A and 100B containing fillers with a particle size of 22 nm. FIG. 12 shows that only the particle size of the filler is different compared to the simulation in FIG. 11, and other conditions are the same.

[0072] From FIGS. 11 and 12, it was confirmed that regardless of the filler particle size in the range of 20 to 45 nm, different estimated luminances are shown depending on whether the hard coat layer has a homogeneous structure or a structure having a first layer in which fillers are present and a second layer made of a resin formed between the first layer and the transparent substrate. Specifically, it was confirmed that the hard coat film in which the hard coat layer is composed of the first layer and the second layer shows a lower estimated luminance than the hard coat film in which the hard coat layer is composed of the first layer. Also, in any case of the filler particle size, the way the estimated luminance changes with respect to the filler distance is common regardless of the presence or absence of the second layer, and it was confirmed that when the filler particle size is 42 nm, a maximum value is taken when the filler distance is about 110 nm.

[0073] According to the hard coat films 100A and 100B according to the above embodiment, since the hard coat layers 2 and 2X contain the filler 21 and the concentration and particle size of the filler 21 are adjusted, when applied to an organic EL display, a black luminance of less than 5.0×10 -4 cd / m 2 which is a standard called True Black can be achieved.

[0074] [Optical laminate] FIG. 13 is a cross-sectional view of an optical laminate according to an 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 is made of a layer of inorganic oxide or inorganic nitride. Here, the phrase "on the hard coat layer 2" is not limited to a configuration provided in contact with the hard coat layer 2, and it may be formed via other layers. 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.

[0075] (Adhesion layer) The adhesion layer 3 is a layer formed to improve the adhesion between the hard coat layer 2 which is an organic film and the optical functional layer 50A which is an inorganic film. The adhesion layer 3 is preferably made of a metal oxide or metal in an oxygen-deficient state. The metal oxide in an oxygen-deficient state refers to a metal oxide in a state where the number of oxygen atoms is less than the stoichiometric composition. Examples of the metal oxide in an oxygen-deficient state include SiOx, AlOx, TiOx, ZrOx, CeOx, MgOx, ZnOx, TaOx, SbOx, SnOx, MnOx, etc. Examples of the metal include Si, Al, Ti, Zr, Ce, Mg, Zn, Ta, Sb, Sn, Mn, In, etc. The adhesion layer 3 may be, for example, one in which x in SiOx exceeds 0 and is less than 2.0. Also, the adhesion layer may be formed from a mixture of multiple types of metals or metal oxides.

[0076] From the viewpoint of maintaining the adhesion between the hard coat film and the optical functional layer and obtaining good optical characteristics, the thickness of the adhesion layer is preferably more than 0 nm and 20 nm or less, and particularly preferably 1 nm or more and 10 nm or less.

[0077] (Optical functional layer) The optical functional layer 50A provided in the optical laminate 200A shown in Fig. 13 is a laminate that exhibits an antireflection 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 a high refractive index layer 4 and a low refractive index layer 5 are alternately laminated in order from the adhesion layer 3 side. In the optical functional layer 50A, the high refractive index layer and the low refractive index layer closest to the transparent substrate 1 are referred to as a first high refractive index layer 4a and a first low refractive index layer 5a, respectively, and the high refractive index layer and the low refractive index layer farthest from the transparent substrate 1 are referred to as a second high refractive index layer 4b and a second low refractive index layer 5b, respectively. The number of layers of the high refractive index layer 4 and the low refractive index layer 5 is not particularly limited, and the number of layers of the high refractive index layer 4 and the low refractive index layer 5 can be any number.

[0078] In the optical laminate 200A shown in Fig. 13, since the optical functional layer 50A is composed of a laminate in which the low refractive index layer 5 and the high refractive index layer 4 are alternately laminated, the light incident from the antifouling layer 6 side interferes with each other by the optical functional layer 50A, thereby reducing the intensity of the reflected light and exhibiting an antireflection function. Therefore, an antireflection function can be obtained that prevents the light incident from the antifouling layer 6 side from being reflected in one direction.

[0079] The low refractive index layer 5 contains, for example, a metal oxide. The low refractive index layer 5 may contain an oxide of Si from the viewpoint of easy availability and cost, and is preferably a layer mainly composed of SiO 2 (oxide of Si), etc. The single-layer film is colorless and transparent. In the present embodiment, the main component of the low refractive index layer 5 means a component contained in the low refractive index layer 5 in an amount of 50% by mass or more. 2 When the low refractive index layer 5 is a layer mainly composed of an oxide of Si, it may contain another element in an amount of less than 50% by mass. The content of an element other than the oxide of Si is preferably 10% or less. As another element, for example, Na can be contained for the purpose of improving durability, Zr, Al, and N can be contained for the purpose of improving hardness, and Zr and Al can be contained for the purpose of improving alkali resistance.

[0080] ​The refractive index of the low refractive index layer 5 is preferably 1.20 to 1.60, more preferably 1.30 to 1.50. Examples of the dielectric used for the low refractive index layer 5 include magnesium fluoride (MgF 2 , refractive index 1.38), etc.

[0081] The refractive index of the high refractive index layer 4 is preferably 2.00 to 2.60, more preferably 2.10 to 2.45. Examples of the dielectric used for the high refractive index layer 4 include 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), etc. When it is desired to impart electrical conductivity to the high refractive index layer 4, for example, ITO or indium zinc oxide (IZO) can be selected.

[0082] The optical functional layer 50A preferably uses, for example, niobium pentoxide (Nb 2 O 5 , refractive index 2.33) as the high refractive index layer 4 and SiO 2 as the low refractive index layer 5.

[0083] The film thickness of the low refractive index layer 5 may be in the range of 1 nm or more and 200 nm or less, and is appropriately selected according to the wavelength range requiring the antireflection function. The film thickness of the high refractive index layer 4 may be, for example, 1 nm or more and 200 nm or less, and is appropriately selected according to the wavelength range requiring the antireflection function. The film thicknesses of the high refractive index layer 4 and the low refractive index layer 5 can be appropriately selected according to the design of the optical functional layer 50A, respectively. For example, from the side of the adhesion layer 3, a high refractive index layer 4 with a thickness of 5 to 50 nm, a low refractive index layer 5 with a thickness of 10 to 80 nm, a high refractive index layer 4 with a thickness of 20 to 200 nm, and a low refractive index layer 5 with a thickness of 50 to 200 nm can be used.

[0084] Among the layers forming the optical functional layer 50A, the low refractive index layer 5 is disposed on the side of the antifouling layer 6. When the low refractive index layer 5 of the optical functional layer 50A is in contact with the antifouling layer 6, the antireflection performance of the optical functional layer 50A becomes good, which is preferable.

[0085] (Antifouling layer) The antifouling layer 6 is formed on the outermost surface of the optical functional layer 50A to prevent the optical functional layer 50A from being soiled. Further, when the antifouling layer 6 is applied to a touch panel or the like, the abrasion resistance suppresses the wear of the optical functional layer 50A. The antifouling layer 6 of the present embodiment is composed of a vapor deposition film formed by vapor-depositing an antifouling material. In the present embodiment, the antifouling layer 6 is formed by vacuum vapor-depositing a fluorine-based organic compound as an antifouling material on one surface of the low refractive index layer 5 constituting the optical functional layer 50A. In the present embodiment, since the antifouling material contains a fluorine-based organic compound, the optical laminate 10 has better antifriction properties and alkali resistance.

[0086] As the fluorine-based organic compound constituting the antifouling layer 6, a compound composed of a fluorine-modified organic group and a reactive silyl group (for example, alkoxysilane) is preferably used. Commercially available products include Optool DSX (manufactured by Daikin Industries, Ltd.), KY-100 series (manufactured by Shin-Etsu Chemical Co., Ltd.), and the like.

[0087] As the fluorine-based organic compound constituting the antifouling layer 6, a compound composed of a fluorine-modified organic group and a reactive silyl group (for example, alkoxysilane) is used. When the low refractive index layer 5 of the optical functional layer 50A in contact with the antifouling layer 6 is made of SiO 2 When used, a siloxane bond is formed between the silanol group, which is the skeleton of the fluorine-based organic compound, and SiO 2 Thus, the adhesion between the optical functional layer 50A and the antifouling layer 6 becomes good, which is preferable.

[0088] The optical thickness of the antifouling layer 6 may be in the range of 1 nm or more and 20 nm or less, 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 applied to touch panel applications or the like. Further, when the thickness of the antifouling layer 6 is 3 nm or more, the liquid resistance and the like of the optical laminate 10 are improved. Further, when the thickness of the antifouling layer 6 is 20 nm or less, the time required for vapor deposition is short, and it can be manufactured efficiently.

[0089] 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 is different from the optical function layer 50A provided in the optical laminate 200A. As shown in FIG. 14, the optical laminate 200B may include 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 in terms of easy availability and cost. The optical function layer 50B is, for example, SiO 2 (oxide of Si) as a main component. SiO 2 The single-layer film is colorless and transparent. In the present embodiment, the main component of the optical function layer 50B means a component contained in the optical function layer 50B in an amount of 50% by mass or more. The optical function layer 50B may be a layer made of SiO 2 .

[0090] 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 function layer 50A, and an antifouling layer 6 on a hard coat film 100B. As in the optical laminate 200C shown in FIG. 15, the optical laminate according to the present embodiment may have a configuration in which an optical function layer is formed on a hard coat film in which the hard coat layer 2X has a first layer 2a and a second layer 2b.

[0091] In the optical laminate according to this embodiment, other layers may be provided on the surface of the transparent substrate 1 opposite to the side where the hard coat layers 2 and 2X and the optical functional layers 50A and 50B are formed. For example, an adhesive layer to be attached to a display, a release layer provided on the adhesive layer, and the like can be mentioned. The adhesive layer is a layer that adheres 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, is peeled off at the time of bonding, and enables the adhesive layer exposed by peeling 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 may be formed via a substrate. However, from the viewpoint of facilitating the handling of the optical laminate and the display to which the optical laminate is attached, it is preferable to have a substrate layer on the transparent substrate 1 side.

[0092] According to the optical laminate according to this embodiment, similar to the hard coat film according to the above embodiment, it is possible to provide an optical laminate having high hardness and good black luminance when applied to an organic EL display.

Examples

[0093] Hereinafter, examples of the present invention will be described. The present invention is not limited to the following examples.

[0094] <Adjustment of Composition for Hard Coat Layer> To produce the hard coat films of Examples 1 to 4 and Comparative Examples 1 to 3 below, a photocurable resin composition mixed with a filler was prepared except for Comparative Example 1. As shown in Tables 1 and 2, the resin composition was prepared by dissolving a filler, acrylate, leveling agent, and photopolymerization initiator in a solvent. Table 1 shows the formulation when the entire resin composition including the solvent is 100%. Table 2 shows the formulation without the solvent. That is, Table 2 shows the formulation when the total solid content is 100%. The % in the table is the mixing ratio in the resin composition and represents mass%.

[0095]

Table 1

[0096]

Table 2

[0097] [Example 1-1] First, as a transparent substrate, a triacetyl cellulose (TAC) substrate with a thickness of 80 μm was prepared. The resin composition of Example 1 shown in Table 1 was applied by a gravure coater so that the thickness of the uncured hard coat layer on the transparent substrate was 10 μm. Then, by irradiating light to cure the resin composition applied on the transparent substrate, a hard coat film was produced in which a hard coat layer composed of a second layer containing the resin component of the transparent substrate and the resin component of the hard coat layer and a first layer containing a filler was formed on the transparent substrate as shown in FIG. 9. In addition, PGMAC-4130Y (manufactured by Nissan Chemical Industries, Ltd.) used as a filler in Example 1-1 is a filler with an average particle size of 42 nm in which the surface of silica particles is modified with a (meth)acrylic group.

[0098] [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, by changing the solvent of the resin composition, the thickness of the first layer in the hard coat layer was made thinner than that in Example 1.

[0099] [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, by changing the solvent of the resin composition to PGM (propylene glycol monomethyl ether), a hard coat film was produced in which a hard coat layer containing a resin and a filler as shown in FIG. 1 was provided in contact with a transparent substrate. PGMAC-3140Y (manufactured by Nissan Chemical Industries, Ltd.) used as the filler is a filler having an average particle size of 22 nm in which the surface of silica particles is modified with a (meth)acrylic group.

[0100] [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 blending ratio of the resin composition.

[0101] [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.

[0102] [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, a hard coat film was produced in which a hard coat layer having no first layer was formed on a transparent substrate by using PGM as the solvent.

[0103] [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, by changing the compounding ratio, the thickness of the first layer was made thinner and the thickness of the second layer was made thicker, and IPA-ST-L (manufactured by Nissan Chemical Industries, Ltd.), that is, silicon dioxide without surface modification, was used as the filler.

[0104] Further, as Examples 1-2, 2-2, 3-2, 4-2 and Comparative Examples 1-2, 2-2, 3-2, an antireflection film was produced by forming an adhesion layer, an optical functional layer and an antifouling layer on the hard coat film layer produced as Examples 1-1, 2-1, 3-1, 4-1 and Comparative Examples 1-1, 2-1, 3-1 by the following method. In some cases, Examples 1-1 and 1-2 may be collectively referred to as Example 1. Other examples and comparative examples may be similarly collectively referred to.

[0105] <Method for producing antireflection film> The surface of the hard coat layer was surface-treated by glow discharge treatment with 5 kW. Subsequently, on the hard coat layer, using an Si target and an Nb target as sputtering targets, an adhesion layer and an optical functional layer were continuously formed by reactive sputtering using a mixed gas of Ar gas and O 2 gas. That is, on the hard coat layer, an adhesion layer made of Si oxide (SiOx, 0 < x < 2) that may have oxygen deficiency with a thickness of 3 nm, and Nb with a thickness of 10 nm 2 O 5 a first high refractive index material layer made of, a first low refractive index material layer made of SiO with a thickness of 26 nm 2 a second high refractive index material layer made of Nb with a thickness of 110 nm 2 O 5 and a second low refractive index material layer made of SiO with a thickness of 85 nm 2 were formed in this order.

[0106] Next, at an internal pressure of 0.01 Pa in the evaporation chamber, an evaporation temperature of 230 °C, and a holding time of 7.2 s, the SiO on the uppermost layer of the optical functional layer 2A 3-nm-thick antifouling layer composed of an alkoxysilane compound (KY1903-1, manufactured by Shin-Etsu Chemical Co., Ltd.) having a perfluoropolyether group was formed by vapor deposition to produce the optical laminate (antireflection film) of the example.

[0107] <Structure evaluation> The cross-sections of the hard coat films prepared in the above examples and comparative examples were observed with an optical microscope to evaluate the laminated structure. In the observed cross-section, the distance from the outermost surface of the filler closest to the transparent substrate was measured and taken as the thickness of the second layer.

[0108] <Evaluation of black luminance> The prepared sample was attached to the organic EL display (170 mm × 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°, luminance: 360 cd / m 2 ². Figure 16 shows the measurement pattern displayed on the organic EL when measuring the black luminance in the examples and comparative examples. As shown in Figure 16, in the measurement pattern, the white region W and the black region B are located in a checkered pattern. A shielding plate was provided on the hard coat film so as to cover the region of the organic EL display excluding the black region B where the measurement region Ra is located. The black region B where the measurement region Ra is located is exposed through the opening provided in the shielding plate. The black region B where the measurement region is located has a size of 80 mm × 100 mm, and the measurement region is located at its center of gravity. Measurement was performed at a measurement angle of 2° with a spectro-radiometer (TOPCON SR-UL1R) placed 60 cm away from the organic EL display. The measurement conditions satisfy the measurement standard of VESA's True Black. The measurement of the black luminance was performed for each case where the hard coat film was applied to the organic EL display and where the antireflection film was applied to the organic EL display.

[0109] <Pencil hardness> The pencil hardness of the produced hard coat film and the antireflection film was measured by a method according to JIS K5600-5-4.

[0110] <Haze value> The haze value of the produced hard coat film was measured by a method according to JIS-K-7136.

[0111]

Table 3

[0112] 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 concentration, black luminance, pencil hardness, and haze values in the first layer are the average values of the three produced samples. Also, the filler concentration in Table 3 is the mass % of the filler in the hard coat layer.

[0113] Also, in the hard coat films where the filler particle size is in the range of 30 nm or more and 50 nm or less as in Example 1 and Example 2, and the filler concentration in the first layer where the filler is present is in the range of 25% to 65%, it was confirmed that the black luminance takes a low value. Also, in the hard coat films where the filler particle size is in the range of 30 nm or less as in Example 3 and Example 4, and the filler concentration in the first layer where the filler is present, or in the homogeneous hard coat layer, is in the range of 25% to 65%, it was confirmed that the black luminance takes a low value. Furthermore, in Examples 1 to 4, the pencil hardness is high, and it is compatible with satisfying the standard called True Black in terms of hardness and VESA. In particular, in Examples 1 to 4, the measurement result of the black luminance when the hard coat film is applied is 3.5×10 -4 (cd / m 2 ) is less than, and among these, in Example 1, Example 3, and Example 4, it is less than 3.0×10 -4 (cd / m 2 ) and in Example 4 it is less than 2.0×10 -4 (cd / m 2) was less than that. Also, the black luminance when the antireflection film was applied was 3.0×10 -4 (cd / m 2 ) or less in all of Examples 1 to 4.

[0114] On the other hand, in the hard coat film in Comparative Example 1 in which the hard coat layer does not contain a filler, since there is no influence of scattering by the filler due to the absence of the filler, the black luminance is low but the pencil hardness is 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 having no second layer is 31.54%, the black luminance was insufficient.

[0115] Also, in Comparative Example 3 using a filler not surface-modified with a (meth)acrylic group, a significantly higher black luminance was shown compared to Example 2 where the conditions were the same except whether the filler was surface-modified or not. This is considered to be because the surface of the filler is not surface-modified with a (meth)acrylic group, the fillers aggregate and the pseudo particle size becomes large, and the scattered light becomes locally large due to the aggregated particles.

[0116] [Examples 5 to 7, Comparative Example 4] Based on the formulations shown in Table 4, the hard coat films described in Examples 5 to 7 and Comparative Example 4 were produced. The resin composition was applied onto TAC, which is a transparent substrate, with a gravure coater to a thickness of 10 μm and cured by irradiating light to produce a hard coat film as shown in FIG. 1. The filler concentration in the hard coat layer of Example 5 corresponds to the data of the filler distance of about 75 nm in the simulation of FIG. 8. The filler concentration in the hard coat layer of Example 6 corresponds to the data of the 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 of the filler distance of about 55 nm in the simulation of FIG. 8. The filler concentration in the hard coat layer of Comparative Example 4 is 0%, and the distance between fillers in the simulation of FIG. 8 is treated as infinite.

[0117]

Table 4

[0118] (Luminance evaluation) For Examples 5 to 7 and Comparative Example 4, data corresponding to the conditions of the simulation whose graph is shown in FIG. 8 were measured by actual measurement. That is, for the hard coat film, luminance was measured using the same shielding plate and spectro-radiometer as those used for measuring the black luminance in the above examples. The luminance was measured by a spectro-radiometer provided 60 cm away from the hard coat film through the opening of the shielding plate.

[0119] FIG. 17 is a graph showing the results of the filler concentration and luminance of Examples 5 to 7 and Comparative Example 4. As shown in FIG. 17, at the same filler concentration, Example 7 shows a lower luminance than Example 5, and Example 6, whose filler concentration is between those of Example 7 and Comparative Example 4, shows a higher luminance than Examples 5 and Comparative Example 4, suggesting the existence of a maximum value. Thus, a correlation was confirmed in the graph based on the simulation results of FIG. 8 and the measured values of FIG. 17, and the validity of the simulation results of FIG. 8 was confirmed.

Explanation of reference numerals

[0120] 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 Masking plate 40 Spectroradiometer 50A, 50B Optical functional 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 contains a filler, The black luminance measured under the following conditions is less than 5.0×10 －４ cd / m ２ 2, and it is a hard coat film. (Condition: Emission angle of 180 degrees, luminance of 360 cd / m ２ A hard coat film is provided in close contact with an organic EL display, a white region and a black region are displayed in a checkered pattern on the organic EL display, a shielding plate is provided so as to cover the surface of the organic EL display except for the black region, and a spectro-radiometer provided 60 cm away from the organic EL display measures the black luminance in the black region.)

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

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

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

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

6. A 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 is an optical laminate composed of a layer of inorganic oxide or a layer of inorganic nitride.

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

8. A further adhesion layer is formed between the hard coat layer and the optical functional layer and is in contact with the hard coat layer and the optical functional layer, The optical functional layer has a high refractive index material layer and a low refractive index layer alternately laminated, The adhesion layer is in contact with the high refractive index material layer. The optical laminate according to claim 6.

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