JP2009204837A - Anti-glare film, anti-glare polarizing sheet, and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an anti-glare film which presents superior anti-glare performance and prevents deterioration of visibility due to fading and, and which, when being disposed on the surface of a high-definition image display device, develops high contrast without glares, and to provide an anti-glare polarizing sheet and an image display device that uses the anti-glare film. <P>SOLUTION: The anti-glare film comprises a resin base film 101a which includes a transparent resin layer 104a and a light-diffusing layer 103a containing fine particles 105a, and is provided with a first fine rugged surface 110a; and a hard coat layer 102a, which is laminated on the surface of the resin base film and is provided with a second fine rugged surface 120a. The anti-glare polarizing plate and the image display device that use the anti-glare film are also provided. The arithmetic average height Pa<SB>1</SB>of the first fine rugged surface is set to 0.4 to 2 μm, and the average length PSm<SB>1</SB>thereof is set to 2 to 40 μm. The arithmetic average height Pa<SB>2</SB>of the second fine rugged surface is set to 0.2 to 0.6 μm, and the average length PSm<SB>2</SB>thereof is set to 20 to 100 μm, as well as satisfies the condition Pa<SB>2</SB><Pa<SB>1</SB>. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is not anti-glare while exhibiting excellent anti-glare performance, does not cause glare when applied to an image display device, exhibits high contrast, and provides good visibility, an anti-glare film. In addition, the present invention relates to an antiglare polarizing plate and an image display device using the antiglare film.

  In an image display device such as a liquid crystal display, a plasma display panel, a cathode ray tube (CRT) display, and an organic electroluminescence (EL) display, visibility is significantly impaired when external light is reflected on the display surface. Conventionally, in order to prevent such reflection of external light, televisions and personal computers that emphasize image quality, video cameras and digital cameras that are used outdoors with strong external light, and mobile phones that display using reflected light In a telephone or the like, a film layer for preventing external light from being reflected is provided on the surface of an image display device. For this film layer, anti-reflection processing technology using interference by optical multilayer film and anti-glare processing technology that blurs the reflected image by scattering incident light by forming fine irregularities on the surface are generally used. ing. In particular, the latter technique of scattering incident light by forming fine irregularities can be manufactured at a relatively low cost, and is therefore widely used in applications such as large monitors and personal computers.

  Conventionally, such an antiglare film, for example, a resin solution in which a filler is dispersed is applied on a base sheet, and the coating film thickness is adjusted so that the filler is exposed on the surface of the coating film. It is manufactured by a method of forming on a sheet. On the other hand, there is also an attempt to develop anti-glare properties only by fine irregularities formed on the surface of the transparent resin layer without containing a filler. For example, in Patent Document 1 (Claims 1 to 6, paragraphs 0043 to 0046), the ionizing radiation curable resin is cured in a state where the ionizing radiation curable resin is sandwiched between the embossing mold and the transparent resin film. On the transparent resin film, the three-dimensional 10-point average roughness and the average distance between adjacent convex portions on the three-dimensional roughness reference surface form fine irregularities satisfying predetermined values, respectively. An antiglare film in which a cured product layer of an ionizing radiation curable resin layer having surface irregularities is laminated is disclosed. However, when such a conventional anti-glare film is arranged on the surface of the image display device, there is a problem that the entire display surface becomes whitish due to scattered light and the display becomes cloudy, so-called whitening is likely to occur. It was.

In addition, when the image display device is high-definition, the pixel of the image display device and the surface uneven shape of the antiglare film interfere with each other. There was a problem. In order to eliminate glare, there is an attempt to scatter light by providing a difference in refractive index between the binder resin and the dispersion filler. However, when such an antiglare film is applied to an image display device, the scattered light As a result, the luminance of black display is increased, resulting in a problem that the contrast is lowered and the visibility is remarkably lowered. In addition, in the antiglare film in which the surface unevenness shape is formed by such a filler, the surface unevenness shape for scattering incident light and the region mainly responsible for the internal scattering of light are simultaneously formed. In addition to designing with a balance between the particle size, concentration, refractive index, and dispersibility of the dispersed particles, precise control is necessary in production, but such design and control is practically difficult. As an attempt to avoid such complicated design and control, Patent Document 2 discloses that the formation of the resin layer having the internal scattering function of light and the formation of the uneven surface shape are performed separately. In the method of coating by dispersing in a resin solution, there is a problem that unexpected aggregation or the like is likely to occur during the drying process.
JP 2002-189106 A JP 2007-101912 A

  The present invention has been made in view of the current situation, and its purpose is to provide excellent anti-glare performance, while preventing a decrease in visibility due to whitishness, and placing it on the surface of a high-definition image display device. Sometimes, an antiglare film that exhibits high contrast without causing glare is provided, and further, an antiglare polarizing plate and an image display device to which the antiglare film is applied.

  As a result of intensive studies to solve the above problems, the inventors of the present invention include at least a transparent resin layer and a light diffusion layer containing fine particles having a refractive index different from the refractive index of the binder resin, and the surface thereof. By laminating a hard coat layer having a fine concavo-convex surface on the surface of the resin base film consisting of a fine concavo-convex surface having a specific shape, the internal scattering characteristics and reflection characteristics of the antiglare film can be independently obtained. As a result, it has been found that an antiglare film can be obtained in which glare is sufficiently prevented and contrast is hardly lowered when applied to an image display device. The present invention has been completed based on such findings and further various studies.

That is, the present invention comprises a multilayer structure including at least one transparent resin layer made of a transparent resin, and at least one light diffusion layer containing a transparent binder resin and fine particles having a refractive index different from that of the transparent binder resin. The present invention relates to an antiglare film comprising a resin base film and a hard coat layer laminated on the surface of the resin base film. In the antiglare film of the present invention, the hard coat layer side surface of the resin base film is composed of a first fine uneven surface having a fine uneven shape, and an arithmetic average in an arbitrary cross-sectional curve of the first fine uneven surface The height Pa ₁ is 0.4 μm or more and 2 μm or less, and the average length PSm ₁ is 2 μm or more and 40 μm or less. Further, the surface of the hard coat layer opposite to the resin base film side is composed of a second fine uneven surface having a fine uneven shape, and an arithmetic average height in an arbitrary cross-sectional curve of the second fine uneven surface. The thickness Pa ₂ is 0.2 μm or more and 0.6 μm or less, the average length PSm ₂ is 20 μm or more and 100 μm or less, and the arithmetic average height Pa ₂ in an arbitrary cross-sectional curve of the second fine uneven surface is It is smaller than the arithmetic average height Pa ₁ in an arbitrary cross-sectional curve of the first fine uneven surface of the material film.

  In the antiglare film of the present invention, the internal haze of the resin base film is preferably 5% or more and 30% or less. Further, the surface haze of the hard coat layer laminated on the first fine uneven surface of the resin base film is 0.5% or more and 15% or less, and the internal haze of the hard coat layer is 2% or less. Preferably there is. More preferably, the internal haze of the hard coat layer is substantially 0%.

  The thickness of the resin base film is preferably 30 μm or more and 250 μm or less, and the thickness of the hard coat layer is preferably 1 μm or more and 10 μm or less. Moreover, it is preferable that both the transparent resin which comprises a transparent resin layer, and the transparent binder resin which comprises a light-diffusion layer are acrylic resins.

  In one preferable embodiment of the present invention, the resin base film has a two-layer structure of one transparent resin layer and one light diffusion layer laminated on the surface of the transparent resin layer. In this case, the hard coat layer is disposed on the surface of the light diffusion layer opposite to the transparent resin layer side.

  In another preferred embodiment of the present invention, the resin base film has a three-layer structure of two transparent resin layers and a light diffusion layer disposed between the two transparent resin layers.

  The antiglare film of the present invention may further have a low reflection film on the second fine uneven surface of the hard coat layer.

  The present invention also provides an antiglare polarizing plate formed by laminating one of the above antiglare films and a polarizing film. In the antiglare polarizing plate of the present invention, the polarizing film is disposed on the resin base film side of the antiglare film.

  The antiglare film or antiglare polarizing plate of the present invention can be combined with an image display element such as a liquid crystal display element or a plasma display panel to form an image display device. That is, according to the present invention, the antiglare film according to any one of the above or the antiglare polarizing plate and an image display element are provided, and the antiglare film or the antiglare polarizing plate has a hard coat layer side. An image display device is provided that is disposed on the outside of the image display element on the viewing side.

  The anti-glare film of the present invention has excellent anti-glare performance, prevents deterioration of visibility due to whitening, and does not cause glare when placed on the surface of a high-definition image display device. Can exhibit high contrast. The anti-glare polarizing plate obtained by combining the anti-glare film of the present invention with a polarizing film also exhibits the same effect. And the image display apparatus which has arrange | positioned the anti-glare film or anti-glare polarizing plate of this invention has high anti-glare performance, and becomes what was excellent in visibility.

<Anti-glare film>
FIG. 1 is a schematic cross-sectional view showing a preferred example of the antiglare film of the present invention. The antiglare film shown in FIG. 1A includes a resin base film 101a and a hard coat layer 102a laminated on the resin base film 101a. The resin base film 101a has a two-layer structure of one transparent resin layer 104a and one light diffusion layer 103a laminated on the transparent resin layer 104a. Dispersed in the light diffusion layer 103a are fine particles 105a having a refractive index different from that of the transparent binder resin serving as the base material of the light diffusion layer 103a. The hard coat 102a layer side surface of the resin base film 101a (that is, the hard coat layer side surface of the light diffusion layer 103a) is composed of a first fine uneven surface 110a having a fine uneven shape. A hard coat layer 102a is laminated on the fine uneven surface 110a. Further, the surface (the outermost surface of the antiglare film) opposite to the resin base film 101a side of the hard coat layer 102a is composed of a second fine uneven surface 120a having a fine uneven shape.

  The antiglare film shown in FIG. 1B includes a resin base film 101b and a hard coat layer 102b laminated on the resin base film 101b. The resin base film 101b has a three-layer structure including two transparent resin layers 104b and a light diffusion layer 103b disposed between the two transparent resin layers 104b. In the light diffusion layer 103b, fine particles 105b having a refractive index different from that of the transparent binder resin that is the base material of the light diffusion layer 103b are dispersed. The hard coat 102b layer side surface of the resin base film 101b (that is, the hard coat layer side surface of the transparent resin layer 104b on the hard coat layer side) is composed of a first fine uneven surface 110b having a fine uneven shape. The hard coat layer 102b is laminated on the first fine uneven surface 110b. Further, the surface (the outermost surface of the antiglare film) opposite to the resin base film 101b side of the hard coat layer 102b is composed of a second fine uneven surface 120b having a fine uneven shape.

  As shown by the above preferred example, the antiglare film of the present invention is a hard resin having a resin base film and a second fine uneven surface laminated on the first fine uneven surface of the resin base film. The resin base film has an internal scattering function, while the hard coating layer has a structure in which the internal scattering function is eliminated or almost eliminated and only the surface reflection characteristic is given. With this configuration, it is possible to independently control the internal scattering characteristics and the reflection characteristics, and while preventing excellent glare-proof performance, deterioration in visibility due to whitening is prevented, and a high-definition image display device When it is arranged on the surface, an antiglare film that expresses high contrast without causing glare can be easily obtained. Hereinafter, the resin base film and the hard coat layer will be described in detail.

(Resin base film)
The resin base film has a multilayer structure including at least one transparent resin layer made of a transparent resin and at least one light diffusion layer containing a transparent binder resin and fine particles having a refractive index different from that of the transparent binder resin. is doing. Here, in the present invention, the arithmetic average height Pa ₁ in an arbitrary cross-sectional curve of the first fine irregular surface of the resin base film is 0.4 μm or more and 2 μm or less, and the average length PSm ₁ is 2 μm or more and 40 μm. It is as follows. These arithmetic average height Pa ₁ and average length PSm ₁ are defined in JIS B 0601 (= ISO 4287). The arithmetic average height Pa is the same as the value called centerline average roughness.

When the arithmetic average height Pa ₁ in an arbitrary cross-sectional curve of the first fine uneven surface of the resin base film is less than 0.4 μm, a hard coat layer is formed on the first fine uneven surface by coating. In this case, the surface of the antiglare film becomes almost flat and does not show sufficient antiglare performance. That is, when a hard coat layer is formed by, for example, applying a curable resin composition on the first fine uneven surface and curing it, the arithmetic average height Pa _{1 of} the first fine uneven surface is 0. When the thickness is less than 4 μm, the arithmetic average roughness Pa ₂ of the second fine uneven surface of the obtained hard coat layer is extremely small, and sufficient antiglare performance is not exhibited. Further, when the arithmetic average height Pa ₁ in an arbitrary cross-sectional curve of the first fine uneven surface is larger than 2 μm, a good anti-glare property is obtained when a hard coat layer is formed on the first fine uneven surface by coating. In order to obtain performance, it becomes difficult to appropriately control the uneven shape of the second fine uneven surface (antiglare film outermost surface) of the hard coat layer. This is because, when the thickness of the hard coat layer is small, the arithmetic mean height Pa ₂ in an arbitrary cross-sectional curve of the second fine uneven surface becomes large due to being greatly affected by the first fine uneven surface. This is because problems such as injury and glare will occur. On the other hand, if the thickness of the hard coat layer is increased in order to reduce the arithmetic average height Pa ₂ of the second fine uneven surface, the average length PSm ₂ of the second fine uneven surface becomes too large, and the texture is increased. It tends to decrease significantly.

In the present invention, the arithmetic average height Pa ₁ and the average length PSm ₁ in an arbitrary cross-sectional curve of the first fine uneven surface of the resin base film are determined using a confocal microscope. It is calculated | required by performing calculation based on JISB0601 from the three-dimensional information of the surface shape obtained. In the measurement, in order to ensure a sufficient reference length, three or more points of a region of 200 μm × 200 μm or more are measured, and an average value thereof is used as a measured value. In order to prevent warping of the resin base film, the measurement is performed by bonding the resin base film to a glass substrate using an optically transparent adhesive so that the fine uneven surface becomes the surface. Done.

  The internal haze of the resin base film is preferably 5% or more, and more preferably 10% or more. By setting the internal haze to 5% or more, glare can be eliminated, and by setting it to 10% or more, glare can be more effectively eliminated. The internal haze of the resin base film is preferably 30% or less. When the internal haze of the resin base film exceeds 30%, when applied to an image display device, the screen becomes dark as a result, and the visibility tends to be impaired. In order to ensure sufficient brightness, the internal haze is more preferably 20% or less. As will be described in detail later, in the antiglare film of the present invention, the internal haze of the hard coat layer is essentially unnecessary because the resin base film has an antiglare property due to scattering. In order to independently control the internal scattering characteristics and the reflection characteristics, it is preferable that the internal haze of the hard coat layer is substantially zero.

  Here, the “internal haze” of the resin base film is measured as follows. That is, first, a resin base film is bonded to a glass substrate using an optically transparent adhesive. Under the present circumstances, the resin base film is bonded so that the surface on the opposite side to the 1st fine unevenness | corrugation surface may turn into a glass substrate side. Next, on the first fine uneven surface, using glycerin, a triacetyl cellulose film (TAC film) having a haze of approximately 0% is bonded, and the resin base film in which the TAC film is bonded, Haze is measured according to the method shown in JIS K 7136. Such a haze measured in a state where the TAC film is laminated on the surface is almost canceled by the TAC film in which the haze (surface haze) due to the first fine uneven surface is bonded onto the uneven surface. Therefore, it can be regarded as the internal haze of the resin base film.

  For the transparent resin used for the transparent resin layer constituting the resin base film and the transparent binder resin used for the light diffusion layer, a substantially optically transparent resin is used. Examples of such resins include acrylic resins such as triacetyl cellulose, polyethylene terephthalate and polymethyl methacrylate, thermoplastic resins such as polycarbonate and amorphous cyclic polyolefins having norbornene compounds as monomers. . The transparent resin constituting the transparent resin layer and the transparent binder resin used for the light diffusion layer may be the same or different materials. Among these resins, it is preferable to use an acrylic resin that is excellent in transparency and weather resistance and has a high surface hardness. Here, the acrylic resin in the present invention means a material obtained by mixing a methacrylic resin, an additive added as necessary, etc., and melt-kneading.

  The methacrylic resin is a polymer mainly composed of methacrylic acid ester. The methacrylic resin may be a homopolymer of one kind of methacrylic acid ester or a copolymer of methacrylic acid ester with other methacrylic acid ester or acrylic acid ester. Examples of the methacrylic acid esters include alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, and butyl methacrylate, and the alkyl group usually has about 1 to 4 carbon atoms. The acrylic ester that can be copolymerized with the methacrylic ester is preferably an alkyl acrylate, such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and the like. The carbon number of the group is usually about 1 to 8. In addition to these, the copolymer contains an aromatic vinyl compound such as styrene which is a compound having at least one polymerizable carbon-carbon double bond in the molecule, a vinyl cyanide compound such as acrylonitrile, and the like. Also good.

  The acrylic resin preferably contains acrylic rubber particles from the viewpoint of impact resistance and film forming property of the film. The amount of acrylic rubber particles that can be contained in the acrylic resin is preferably 5% by weight or more, more preferably 10% by weight or more. The upper limit of the amount of the acrylic rubber particles is not critical, but if the amount of the acrylic rubber particles is too large, the surface hardness of the film is lowered, and when the film is subjected to surface treatment, it is resistant to the organic solvent in the surface treatment agent. Solvent property decreases. Therefore, the amount of acrylic rubber particles that can be contained in the acrylic resin is preferably 80% by weight or less, and more preferably 60% by weight or less.

  The acrylic rubber particles are particles containing an elastic polymer mainly composed of an acrylate ester as an essential component. The acrylic rubber particles may have a single-layer structure consisting essentially only of the elastic polymer. It may have a multi-layer structure in which the coalescence is one layer. Specifically, as this elastic polymer, 50 to 99.9% by weight of an alkyl acrylate and at least one kind of other vinyl monomer copolymerizable therewith, 0 to 49.9% by weight, A cross-linked elastic copolymer obtained by polymerization of a monomer comprising 0.1 to 10% by weight of a polymerizable cross-linkable monomer is preferably used.

  Examples of the alkyl acrylate include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and the like, and the alkyl group usually has about 1 to 8 carbon atoms. Examples of the other vinyl monomers copolymerizable with the alkyl acrylate include compounds having one polymerizable carbon-carbon double bond in the molecule. Examples thereof include methacrylic acid esters such as methyl acid, aromatic vinyl compounds such as styrene, vinylcyan compounds such as acrylonitrile, and the like. Examples of the copolymerizable crosslinkable monomer include a crosslinkable compound having at least two polymerizable carbon-carbon double bonds in the molecule. (Meth) acrylates of polyhydric alcohols such as (meth) acrylate and butanediol di (meth) acrylate, alkenyl esters of (meth) acrylic acid such as allyl (meth) acrylate and methallyl (meth) acrylate, divinyl Examples include benzene. In this specification, (meth) acrylate refers to methacrylate or acrylate, and (meth) acrylic acid refers to methacrylic acid or acrylic acid.

  In addition to the acrylic rubber particles, the acrylic resin contains normal additives such as ultraviolet absorbers, organic dyes, pigments, inorganic dyes, antioxidants, antistatic agents, surfactants, and the like. Also good. Among these, an ultraviolet absorber is preferably used for improving weather resistance. Examples of the ultraviolet absorber include 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2- (5 -Methyl-2-hydroxyphenyl) -2H-benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (3,5-di -Tert-butyl-2-hydroxyphenyl) -2H-benzotriazole, 2- (3-tert-butyl-5-methyl-2-hydroxyphenyl) -5-chloro-2H-benzotriazole, 2- (3,5 -Di-tert-butyl-2-hydroxyphenyl) -5-chloro-2H-benzotriazole, 2- (3,5-di-tert-amyl-2-hydroxypheny ) Benzotriazole ultraviolet absorbers such as -2H-benzotriazole, 2- (2'-hydroxy-5'-tert-octylphenyl) -2H-benzotriazole; 2-hydroxy-4-methoxybenzophenone, 2- Hydroxy-4-octyloxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxy-4'-chlorobenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4, Examples include 2-hydroxybenzophenone ultraviolet absorbers such as 4′-dimethoxybenzophenone; salicylic acid phenyl ester ultraviolet absorbers such as p-tert-butylphenyl salicylic acid ester and p-octylphenyl salicylic acid ester. It may be used two or more thereof. When the acrylic resin contains an ultraviolet absorber, the amount is usually 0.1% by weight or more, preferably 0.3% by weight or more, and preferably 2% by weight or less.

  Fine particles dispersed in the light diffusion layer are inorganic particles such as calcium carbonate, barium sulfate, titanium oxide, aluminum hydroxide, silica, glass, talc, mica, white carbon, magnesium oxide, zinc oxide, and fatty acids in these inorganic particles. Inorganic particles such as those that have been surface-treated may be used, but inorganic particles generally have a large particle size distribution and are not easily dispersed in a transparent binder resin. It is preferable to use resin particles because the difference in the refractive index of the resin tends to decrease the light transmittance. The refractive index of the fine particles needs to have a value different from the refractive index of the transparent binder resin in order to provide a light diffusion function, and the refractive index difference between the two is 0.01 or more. Is preferred. Moreover, in order to give a suitable internal haze value to the resin base film, it is preferable not to make this difference in refractive index very large. For example, the difference in refractive index between the two is preferably less than 0.02. The refractive index of the fine particles is appropriately selected in consideration of the type of the transparent binder resin used and the like, but when using the transparent binder resin as described above, the refractive index of the fine particles is 1.43 or more and 1.55 or less. It is preferable to select from a range. When the acrylic resin is used as the transparent binder resin, the refractive index of the fine particles is from about 1.47 to 1.51 because the refractive index of the acrylic resin is generally about 1.49. Preferably, the selection is made so as to satisfy the above conditions.

  The fine particles are preferably spherical or almost spherical considering the isotropic and uniformity of scattering. Further, particles having a shape with irregularities on the surface and amorphous particles may cause unexpected scattering due to a structure such as minute irregularities on the surface smaller than the particle size. The weight average particle diameter of the fine particles is preferably 4 μm or more and 20 μm or less, and more preferably 5 μm or more and 12 μm or less. When the weight average particle diameter of the fine particles is less than 4 μm, the scattered light intensity on the wide angle side increases, and as a result, when applied to an image display device, the contrast tends to decrease. Further, when the weight average particle diameter exceeds 20 μm, the required scattering effect may not be obtained, or it may be necessary to increase the thickness of the resin base film in order to obtain the required scattering effect. .

  Specific examples of the fine particles preferably used include spherical or nearly spherical resin beads. Examples of suitable resin beads include melamine beads (refractive index 1.57), polymethyl methacrylate beads (refractive index). 1.49), methyl methacrylate / styrene copolymer resin beads (refractive index 1.50 to 1.59), polycarbonate beads (refractive index 1.55), polyethylene beads (refractive index 1.53), polychlorinated Examples thereof include vinyl beads (refractive index 1.46) and silicone resin beads (refractive index 1.46).

  In the light diffusion layer, the fine particles are preferably contained in an amount of 5 to 30 parts by weight with respect to 100 parts by weight of the transparent binder resin. If the content of the fine particles is less than 5 parts by weight, uniform and sufficient internal scattering cannot be obtained, and glare tends to occur when an antiglare film is obtained. On the other hand, if the content of fine particles exceeds 30 parts by weight, internal scattering increases, resulting in high haze, the screen becomes dark when applied to an image display device, and visibility is impaired. The scattered light intensity on the side also rises and tends to lower the contrast when applied to an image display device.

  The resin composition used for forming the light diffusion layer can be obtained by mixing the transparent binder resin (for example, methacrylic resin, acrylic rubber particles and other additives) and the fine particles, and melt-kneading them. .

  The thickness of the resin base film is preferably 30 μm or more and 250 μm or less, and more preferably 40 μm or more and 170 μm or less. When the thickness of the resin base film is less than 30 μm, it may be difficult to obtain sufficient scattering characteristics required in the present invention. Moreover, it is not preferable that the thickness of the resin base film exceeds 250 μm from the viewpoint of the recent demand for thinning of the image display device and the cost. From the viewpoint of reducing the thickness of the entire antiglare film, the thickness of the resin base film is more preferably 150 μm or less, and further preferably 120 μm or less. The thickness of the transparent resin layer is not particularly limited, but can be, for example, 10 μm or more and 50 μm or less, and preferably 15 μm or more and 40 μm or less. The thickness of the light diffusion layer is not particularly limited, but can be, for example, 20 μm or more and 150 μm or less, and preferably 30 μm or more and 90 μm or less.

  The method for obtaining the resin base film used in the present invention is not particularly limited, and various generally known methods can be used, but a coextrusion molding method can be preferably used. In the co-extrusion molding method, the resin composition containing the transparent resin constituting the transparent resin layer and the resin composition containing the transparent binder resin and fine particles constituting the light diffusion layer are put into separate extruders, respectively. While extruding from a die for coextrusion molding while heating and kneading, a resin film corresponding to the transparent resin layer and a resin film corresponding to the light diffusion layer are, for example, in the order shown in FIG. A laminated film that is laminated and integrated is obtained. The laminated film after coextrusion molding is sandwiched between, for example, molding rolls or belts, and molding is performed by narrowing the pressure while keeping at least one side, preferably both sides of the laminated film in contact with the roll or belt surface. Thus, a resin base film can be obtained. As the extruder, a single screw extruder, a twin screw extruder, or the like can be used. As the die, a feed block die, a multi-manifold die, or the like can be used.

  The method of forming a film by bringing the laminated film obtained by coextrusion molding into contact with the roll or belt surface as described above is preferable in that a resin base film having a good first fine uneven surface property can be obtained. When this method is used, the surface shape of the first fine irregular surface is such that the content of the fine particles, the particle size of the fine particles, the thickness of the light diffusion layer or the transparent resin layer, the roll or belt temperature, and the like are within the above preferred ranges. It can be controlled by adjusting as appropriate. Further, when film formation is performed by bringing both surfaces of the laminated film into contact with the roll or belt surface, the surface smoothness and surface glossiness of the surface opposite to the first fine uneven surface can be improved. In order to further improve the surface smoothness and surface glossiness, it is preferable that the roll or belt surface in contact with the surface opposite to the first fine uneven surface is a mirror surface.

  Moreover, in order to provide the 1st fine uneven surface on the resin base film surface, a roll having a fine uneven surface as a roll or belt in contact with the surface on the fine uneven surface side used for forming the laminated film or A belt may be used. In this case, the first fine uneven surface on the surface of the resin base film is formed by transferring the fine uneven shape on the roll or belt surface to the laminated film.

  Moreover, as a method for forming the first fine uneven surface of the resin base film, in addition to the above-described method, the resin base is formed so that a part of the fine particles dispersed in the light diffusion layer protrude from the surface of the light diffusion layer. Examples thereof include a method for forming a film, a hot embossing method, and a blasting method.

  As shown in FIG. 1 (a), the resin base film can have a two-layer structure comprising a transparent resin layer and a light diffusion layer laminated thereon, or in FIG. 1 (b). As shown, a three-layer structure in which the light diffusion layer is held between two transparent resin layers can be obtained. Of these, a two-layer structure as shown in FIG. In the case of a two-layer structure, the surface of the light diffusion layer is exposed on one surface of the resin base film, and the surface unevenness (first fine uneven surface) of the light diffusion layer is It can utilize for the 2nd fine uneven surface formation. On the other hand, when the three-layer structure as shown in FIG. 1B is used, the surface unevenness (first fine uneven surface) of the transparent resin layer on the upper side (side on which the hard coat layer is formed) is used. The fine surface irregularities of the hard coat layer can be formed, but in this case, the shape control of the second fine irregularities surface may be more complicated than in the case of the two-layer structure. In addition to the above three-layer structure, the resin base film may be a laminate of four or more layers in which transparent resin layers and light diffusing agents are alternately arranged (in this case, the uppermost layer is a transparent resin layer). Or a light diffusion layer), but in view of cost and the like, a two-layer structure is preferable.

(Hard coat layer)
The anti-glare film of this invention is equipped with the hard-coat layer laminated | stacked on the 1st fine uneven surface of the resin base film. By forming a hard coat layer, it is possible to impart hardness to the antiglare film and prevent scratches, dull the first fine uneven surface shape, and provide excellent antiglare performance, particularly reflection characteristics, as an antiglare film. The shown uneven surface (second fine uneven surface) can be formed on the outermost surface of the antiglare film. Therefore, in the present invention, the arithmetic average height Pa ₂ in the arbitrary cross-sectional curve of the _second fine uneven surface is made smaller than the arithmetic average height Pa ₁ in the arbitrary cross-sectional curve of the first fine uneven surface. . In order to produce an antiglare film so that the arithmetic average height Pa ₂ is equal to or higher than the arithmetic average height Pa ₁ , the second is independent of the first fine uneven surface formation of the resin base film. Therefore, it is necessary to control the shape of the surface of the fine unevenness, which makes the design of the antiglare film complicated and makes it difficult to obtain the second fine uneven surface shape for obtaining preferable optical characteristics.

Specifically, the shape of the second fine uneven surface of the hard coat layer is such that the arithmetic average height Pa ₂ in an arbitrary cross-sectional curve in the surface is 0.2 μm or more and 0.6 μm or less, and the average length PSm. ₂ is controlled to be 20 μm or more and 100 μm or less. When the arithmetic average height Pa _{2 of} the second fine uneven surface is less than 0.2 μm, the antiglare film surface tends to be almost flat and does not exhibit sufficient antiglare performance. In addition, when the arithmetic average height Pa _{2 of} the second fine uneven surface is larger than 0.6 μm, problems such as whitening and glare may occur. On the other hand, when the average length PSm ₂ in an arbitrary cross-sectional curve of the second fine uneven surface is less than 20 μm, the surface shape becomes rough and problems such as whitening tend to occur. Further, when the average length PSm ₂ of the second fine uneven surface is larger than 100 μm, the texture tends to be remarkably lowered. The arithmetic average height Pa ₂ and average length PSm ₂ of the second fine uneven surface are measured in the same manner as the first fine uneven surface.

The method for forming the hard coat layer having the arithmetic average height Pa ₂ and the average length PSm ₂ in the above preferable ranges is not particularly limited, but for example, UV curing is performed on the first fine uneven surface of the resin base film. A coating liquid containing a hard coat resin such as a resin, a thermosetting resin, or an electron beam curable resin was applied at an appropriate film thickness so that the unevenness on the first fine uneven surface of the resin base film was not completely buried. Thereafter, a method of curing the resin layer can be mentioned. Under the present circumstances, in order to form the said preferable fine uneven | corrugated shape on the surface of a hard-coat layer, the solid content rate of a coating liquid at the time of coating, a viscosity, a film thickness, etc. are adjusted suitably.

  Here, the solid content ratio, the viscosity and the film thickness of the coating liquid can be appropriately adjusted according to the desired second fine uneven surface shape and the first fine uneven surface shape of the resin base film. Specifically, the solid content of the coating liquid is preferably 20 to 80% by weight, and the viscosity is preferably 1 to 100 mPa · s. The film thickness of the resin layer formed by applying the coating liquid is preferably adjusted so that the cured resin layer, that is, the hard coat layer has a thickness of 1 μm to 10 μm. When the thickness of the hard coat layer is less than 1 μm, sufficient hardness cannot be obtained, the antiglare film surface tends to be easily damaged, and the effect of smoothing the second fine uneven surface shape is insufficient. There is a risk of becoming. In addition, when the thickness of the hard coat layer is greater than 10 μm, the film tends to break, the film tends to curl due to curing shrinkage of the hard coat layer, and the productivity is lowered. As a result, it becomes difficult to form a preferable fine uneven shape on the surface of the hard coat layer.

  As the hard coat resin for forming the hard coat layer, an ultraviolet curable resin, a thermosetting resin, an electron beam curable resin, or the like can be used, but an ultraviolet curable resin is preferably used from the viewpoint of productivity, hardness, and the like. Is done. A commercially available product can be used as the ultraviolet curable resin. For example, a mixture of a polyfunctional acrylate such as trimethylolpropane triacrylate or pentaerythritol tetraacrylate, or two or more of them and a photopolymerization initiator can be used as an ultraviolet curable resin. Examples of the photopolymerization initiator include “Irgacure 907” (manufactured by Ciba Specialty Chemicals), “Irgacure 184” (manufactured by Ciba Specialty Chemicals), and “Lucirin TPO” (manufactured by BASF). A commercially available product such as can be suitably used. When such an ultraviolet curable resin is used, a hard coat layer can be formed by applying a coating liquid containing the resin to a resin base film and irradiating with ultraviolet rays.

  The surface haze of the hard coat layer is preferably 0.5% or more and 15% or less, and the internal haze is preferably 2% or less. Here, the surface haze and internal haze of the hard coat layer are measured as follows. That is, first, after forming a hard coat layer on a resin substrate film to produce an antiglare film, the transparent substrate is used to attach the antiglare film and the glass substrate so that the resin substrate film side becomes the bonding surface. The haze is measured according to JIS K 7136. The haze corresponds to the entire haze of the antiglare film (the “overall haze” of the antiglare film). Next, a triacetyl cellulose film having a haze of almost 0 is bonded to the second fine uneven surface of the hard coat layer using glycerin, and the haze is measured again in accordance with JIS K 7136. Since the haze caused by the surface irregularities of the hard coat layer (surface haze of the hard coat layer) is almost countered by the triacetyl cellulose film bonded onto the surface irregularities, the haze is substantially prevented. It can be regarded as the “inner haze” of the glare film. Therefore, the “internal haze” of the hard coat layer is obtained from the following formula (1).

Internal haze of hard coat layer = internal haze of anti-glare film−internal haze of resin base film (1)
In addition, the internal haze of the resin base film is measured by the method described above.

Further, the “surface haze” of the hard coat layer is obtained from the following formula (2).
Surface haze of hard coat layer = total haze of antiglare film−internal haze of antiglare film (2)
As described above, in the present invention, in order to control the internal scattering characteristics and the reflection characteristics independently, the internal scattering characteristics are mainly imparted to the resin base film, so the internal haze of the hard coat layer is 2 % Or less, preferably substantially 0%. When the internal haze of the hard coat layer is substantially 0%, the haze of the hard coat layer substantially consists of only the surface haze. The surface haze of the hard coat layer is 15% or less from the viewpoint of suppressing whitening, and is preferably 5% or less in order to suppress whitening more effectively. However, when it is less than 0.5%, it is not preferable because sufficient antiglare property is not exhibited.

  The antiglare film of the present invention which is a laminate of the resin base film and the hard coat layer as described above is normal to the hard coat layer side when light is incident at an incident angle of 20 ° from the resin base film side. Relative scattered light intensity T (20) observed in FIG. 2 shows a value of 0.0001% or more and 0.0006% or less, and when light is incident from the resin substrate film side at an incident angle of 30 °, the hard coat layer side method It is preferable that the relative scattered light intensity T (30) observed in the linear direction shows a value of 0.00004% or more and 0.0002% or less. Here, the relative scattered light intensity T (20) in the normal direction of the hard coat layer when the light is incident from the resin base film side at an incident angle of 20 ° and the light is incident at an incident angle of 30 ° and T (30) will be described.

  FIG. 2 shows light incident from the resin base film side (the side opposite to the second fine uneven surface of the hard coat layer) and scattered light in the normal direction of the hard coat layer side (second fine uneven surface side). It is the perspective view which showed typically the incident direction of light when measuring an intensity | strength, and a transmitted scattered light intensity | strength measurement direction. Referring to FIG. 2, light 203 incident at an angle φ (incident angle) from normal 202 on the resin base film side of antiglare film 201 is transmitted in the direction of normal 202 on the hard coat layer side. The intensity of the transmitted scattered light 204 is measured, and a value obtained by dividing the transmitted scattered light intensity by the light intensity of the light source is defined as a relative scattered light intensity T (φ). That is, when light 203 is incident at an angle of 20 ° from the normal line on the resin base film side of the antiglare film 201, the intensity of the transmitted scattered light 204 observed in the direction of the normal line 202 on the hard coat layer side is determined by the light source. When the value divided by the light intensity is T (20) and the light 203 is incident at an angle of 30 ° from the normal 202 on the resin base film side of the antiglare film 201, the direction of the normal 202 on the hard coat layer side T (30) is a value obtained by dividing the intensity of the transmitted scattered light 204 observed in step 1 by the light intensity of the light source. The light 203 is incident such that the direction of the light 203 incident from the resin base film side and the normal line 202 of the antiglare film are on the same plane (plane 209 in FIG. 2).

  When the relative scattered light intensity T (20) at 20 ° incidence exceeds 0.0006%, when this antiglare film is applied to an image display device, the luminance during black display increases due to the scattered light. , Reduce the contrast. Further, when the relative scattered light intensity T (20) at 20 ° incidence is less than 0.0001%, the scattering effect is low, and glare occurs when applied to a high-definition image display device. Similarly, even when the relative scattered light intensity T (30) at 30 ° incidence exceeds 0.0002%, when this antiglare film is applied to an image display device, the luminance at the time of black display due to the scattered light. Increases and decreases contrast. Also, when the relative scattered light intensity T (30) at 30 ° incidence is less than 0.00004%, the scattering effect is low, and glare occurs when applied to a high-definition image display device. In particular, when the antiglare film is applied to a liquid crystal display that is not self-luminous, the effect of increasing the brightness due to scattering caused by light leakage during black display is large, and therefore the relative scattered light intensities T (20) and T (30) are high. If it exceeds the preferable range, the contrast is remarkably lowered and the visibility is impaired.

  3 shows the relative scattered light intensity (logarithmic scale) measured by changing the incident angle φ from the resin base film side of the antiglare film of the present invention (antiglare film 201 in FIG. 2) with respect to the incident angle φ. It is an example of the graph plotted. Such a graph representing the relationship between the incident angle and the relative scattered light intensity, or the relative scattered light intensity for each incident angle read therefrom may be referred to as a transmission scattering profile. As shown in this graph, the relative scattered light intensity has a peak at an incident angle of 0 °, and the scattered light intensity tends to decrease as the angle from the normal direction of the incident light 203 increases. Incidentally, the plus (+) and minus (−) of the incident angle depends on the direction of the incident light 203 around the normal direction (0 °) and the inclination of the incident light in the plane 209 including the normal line 202. It is determined. Therefore, the transmission / scattering profile usually appears symmetrically about the incident angle of 0 °. In the example of the transmission scattering profile shown in FIG. 3, the relative scattered light intensity T (0) at 0 ° incidence shows a peak at about 15%, and the relative scattered light intensity T (20) at 20 ° incidence is about The relative scattered light intensity T (30) at 0.0003% and 30 ° incidence is about 0.00006%.

  In measuring the relative scattered light intensity of the antiglare film, it is necessary to accurately measure the relative scattered light intensity of 0.001% or less. Therefore, it is effective to use a detector with a wide dynamic range. As such a detector, for example, a commercially available optical power meter can be used, and an aperture is provided in front of the detector of this optical power meter so that the angle at which the antiglare film is viewed is 2 °. Measurements can be made using an angular photometer. Visible light of 380 to 780 nm can be used as incident light, and a collimated light emitted from a light source such as a halogen lamp may be used as a measurement light source, or parallelism with a monochromatic light source such as a laser. Higher ones may be used. Moreover, in order to prevent the curvature of a film, it is preferable to use it for a measurement, after bonding to a glass substrate so that an uneven surface may become the surface using an optically transparent adhesive.

  In view of the above, the relative scattered light intensities T (20) and T (30) defined in the present invention are measured as follows. The antiglare film is bonded to a glass substrate so that the uneven surface becomes the surface, and parallel light from a He-Ne laser is irradiated from the direction inclined at a predetermined angle with respect to the film normal on the glass surface side. Then, the transmitted scattered light intensity in the normal direction of the film is measured on the anti-glare film uneven surface (second fine uneven surface) side. For the measurement of transmitted scattered light intensity, “3292 03 Optical Power Sensor” and “3292 Optical Power Meter” manufactured by Yokogawa Electric Corporation are used for both T (20) and T (30).

  FIG. 4 is a diagram showing the relationship between the relative scattered light intensities T (20) and T (30) and the contrast. As is apparent from FIG. 4, when the relative scattered light intensity T (20) exceeds 0.0006% or T (30) exceeds 0.0002%, the contrast tends to decrease by 10% or more, and the visibility tends to be impaired. You can see that The contrast was measured by the following procedure. First, the polarizing plate on the back side and the display surface side is peeled off from a commercially available liquid crystal television (“LC-42GX1W” manufactured by Sharp Corporation), and instead of the original polarizing plate, Sumitomo A polarizing plate “Sumikaran SRDB31E” manufactured by Chemical Co., Ltd. was bonded via an adhesive so that each absorption axis coincided with the absorption axis of the original polarizing plate. And the anti-glare film which has the structure similar to the anti-glare film which concerns on this invention which shows various scattered light intensity | strength was bonded through the adhesive so that an uneven surface might become the surface. Next, the liquid crystal television thus obtained was activated in a dark room, and using a luminance meter “BM5A” manufactured by Topcon Corporation, the luminance in the black display state and the white display state was measured, and the contrast was calculated. Here, the contrast is represented by the ratio of the luminance in the white display state to the luminance in the black display state.

  The antiglare film of the present invention has a reflectance R (30) at a reflection angle of 30 ° of 0.05% or more and 2% or less when light is incident from the hard coat layer side at an incident angle of 30 °. The reflectance R (40) at a reflection angle of 40 ° is 0.0001% or more and 0.005% or less, and the reflectance R (50) at a reflection angle of 50 ° is 0.00001% or more and 0.0005% or less. It is preferable. By making the reflectance R (30), the reflectance R (40) and the reflectance R (50) within the above ranges, the anti-glare is more effectively suppressed while showing excellent anti-glare performance. A film is provided.

  Here, the reflectance for each angle when light is incident at an incident angle of 30 ° from the hard coat layer side will be described. FIG. 5 is a perspective view schematically showing an incident direction and a reflection direction of light from the hard coat layer side with respect to the antiglare film when the reflectance is obtained. Referring to FIG. 5, the reflected light in the direction of the reflection angle of 30 °, that is, the regular reflection direction 506 with respect to the light 505 incident at an angle of 30 ° from the normal 502 on the hard coat layer side of the antiglare film 501. Let R (30) be the reflectance (that is, regular reflectance). Of the light 507 reflected at an arbitrary reflection angle θ, the reflectance of reflected light at θ = 40 ° and the reflectance of reflected light at θ = 50 ° are R (40) and R (50), respectively. . Note that the direction of reflected light when measuring the reflectance (the specular reflection direction 506 and the reflection direction of the light 507 reflected at the reflection angle θ) is within the plane 509 including the direction of the incident light 505 and the normal line 502. To do.

  When the regular reflectance R (30) exceeds 2%, a sufficient antiglare function cannot be obtained, and the visibility tends to decrease. On the other hand, even if the regular reflectance R (30) is too small, since it tends to cause whitening, it is preferably 0.05% or more. The regular reflectance R (30) is more preferably 1.5% or less, particularly 0.7% or less. On the other hand, if R (40) exceeds 0.005% or R (50) exceeds 0.0005%, the antiglare film is whitened and the visibility tends to be lowered. That is, for example, even when black is displayed on the display surface with an anti-glare film installed on the forefront of the display device, a whitish color occurs that picks up light from the surroundings and makes the display surface entirely white. There is a tendency. Therefore, it is preferable that R (40) and R (50) are not so large. On the other hand, R (40) is generally preferably 0.0001% or more, and R (50) is generally 0, since sufficient antiglare properties are not exhibited even if the reflectance at these angles is too small. It is preferably 0.0001% or more. R (50) is more preferably 0.0001% or less.

  FIG. 6 shows the reflection of the light 507 reflected at the reflection angle θ with respect to the light 505 incident at an angle of 30 ° from the normal 502 on the hard coat layer side of the antiglare film of the present invention (antiglare film 501 in FIG. 5). It is an example of the graph which plotted the relationship between angle (theta) and a reflectance (a reflectance is a logarithmic scale). Such a graph representing the relationship between the reflection angle and the reflectance, or the reflectance for each reflection angle read therefrom may be referred to as a reflection profile. As shown in this graph, the regular reflectance R (30) is a reflectance peak with respect to the light 505 incident at 30 °, and the reflectance tends to decrease as the angle deviates from the regular reflection direction. In the example of the reflection profile shown in FIG. 6, the regular reflectance R (30) is about 0.2%, R (40) is about 0.0004%, and R (50) is about 0.00004%. .

  In measuring the reflectance of the antiglare film, it is necessary to accurately measure a reflectance of 0.001% or less as in the case of the relative scattered light intensity. Therefore, it is effective to use a detector with a wide dynamic range. As such a detector, for example, a commercially available optical power meter can be used, and an aperture is provided in front of the detector of this optical power meter so that the angle at which the antiglare film is viewed is 2 °. Measurements can be made using an angular photometer. As incident light, visible light of 380 to 780 nm can be used, and as a measurement light source, a collimated light emitted from a light source such as a halogen lamp may be used, or a monochromatic light source such as a laser is used in parallel. A high degree may be used. In the case of an antiglare film having a smooth and transparent back surface, reflection from the back surface of the antiglare film may affect the measured value. For example, the smooth surface of the antiglare film is adhered to a black acrylic resin plate with an adhesive or It is preferable that only the reflectance of the outermost surface of the antiglare film (second fine uneven surface) can be measured by optical adhesion using a liquid such as water or glycerin.

  In view of the above, the reflectances R (30), R (40) and R (50) defined in the present invention are measured as follows. The parallel surface from the He-Ne laser is irradiated on the uneven surface (second fine uneven surface) of the antiglare film from a direction inclined by 30 ° with respect to the film normal, and the film normal and the light incident direction are determined. Measurement of the change in the angle of the reflectance in the plane that contains it. In the measurement of reflectance, both “3292 03 optical power sensor” and “3292 optical power meter” manufactured by Yokogawa Electric Corporation are used.

The antiglare film of the present invention may have a low reflection film on the outermost surface, that is, the second fine uneven surface of the hard coat layer. Even in the absence of a low reflection film, a sufficient antiglare function is exhibited, but the antiglare property can be further improved by providing a low reflection film on the outermost surface. The low reflection film can be formed by providing a layer of a low refractive index material having a lower refractive index on the hard coat layer. Specific examples of such a low refractive index material include lithium fluoride (LiF), magnesium fluoride (MgF ₂ ), aluminum fluoride (AlF ₃ ), cryolite (3NaF · AlF ₃ or Na ₃ AlF _6). ) And other inorganic low-reflective materials containing acrylic resin, epoxy resin, etc .; fluorine-based or silicone-based organic compounds, thermoplastic resins, thermosetting resins, UV-curable resins, etc. An organic low reflection material can be mentioned.

<Anti-glare polarizing plate>
The anti-glare film of the present invention has an excellent anti-glare effect, is effectively prevented from being whitish, and can effectively suppress the occurrence of glare and a decrease in contrast, so that it has excellent visibility when mounted on an image display device. It will be. When the image display device is a liquid crystal display, this antiglare film can be applied to the polarizing plate. In other words, in general, there are many polarizing plates in which a protective film is bonded to at least one surface of a polarizing film made of a polyvinyl alcohol-based resin film adsorbed and oriented with iodine or a dichroic dye. The antiglare film of the present invention is used. By attaching the polarizing film and the antiglare film of the present invention on the resin base film side of the antiglare film, an antiglare polarizing plate can be obtained. In this case, the other surface of the polarizing film may be in a state where nothing is laminated, another protective film or an optical film may be laminated, and an adhesive layer for bonding to a liquid crystal cell. May be formed. In addition, the antiglare film of the present invention is bonded on the side of the resin substrate film on the protective film of the polarizing plate having a protective film bonded to at least one surface of the polarizing film to obtain an antiglare polarizing plate. You can also. Furthermore, in the polarizing plate having a protective film bonded to at least one side, after bonding the resin base film to the polarizing film as the protective film, by forming the hard coat layer on the resin base film, It can also be set as an anti-glare polarizing plate.

<Image display device>
The image display device of the present invention is a combination of the antiglare film or the antiglare polarizing plate of the present invention and an image display element. Here, the image display element is typically a liquid crystal panel that includes a liquid crystal cell in which liquid crystal is sealed between upper and lower substrates and displays an image by changing the alignment state of the liquid crystal by applying a voltage. The antiglare film or the antiglare polarizing plate of the present invention can also be applied to various known displays such as a display panel, a CRT display, and an organic EL display. In the image display device of the present invention, the antiglare film is disposed on the viewing side with respect to the image display element. Under the present circumstances, it arrange | positions so that the uneven surface of an anti-glare film, ie, a hard-coat layer side, may become an outer side (viewing side). The antiglare film may be directly bonded to the surface of the image display element. When the liquid crystal panel is used as the image display element, for example, as described above, the antiglare film is bonded to the surface of the liquid crystal panel via the polarizing film. You can also. Thus, the image display device provided with the antiglare film of the present invention can scatter incident light due to the unevenness of the surface of the antiglare film and blur the reflected image, giving excellent visibility.

  In addition, even when the antiglare film of the present invention is applied to a high-definition image display device, the glare as seen in the conventional antiglare film does not occur, sufficient reflection prevention, It has the functions of prevention, suppression of glare, and reduction of contrast reduction.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. In the examples, “%” and “part” representing the content or amount used are based on weight unless otherwise specified. Moreover, the evaluation method of the anti-glare film in the following examples is as follows.

(1) Measurement of fine uneven surface shape The surface shapes of the first fine uneven surface of the resin substrate film and the second fine uneven surface of the antiglare film were measured by the following method. That is, after bonding the resin substrate film or the antiglare film to the glass substrate using an optically transparent adhesive so that the first fine uneven surface or the second fine uneven surface becomes the surface, Three-dimensional information of the surface shape was obtained using a confocal microscope “PLμ2300” manufactured by Sensofar. In the measurement, three or more areas of 200 μm × 200 μm or more were performed, and the average value was used as the measurement value. At the time of measurement, the magnification of the objective lens was 50 times. Next, based on the measurement data, the arithmetic average heights Pa ₁ and Pa ₂ , the maximum cross-sectional heights Pt ₁ and Pt ₂ , and the average lengths PSm ₁ and Psm in the cross-section curve are calculated according to JIS B 0601. ₂ was sought.

(2) Measurement of thickness of resin base film and hard coat layer The thickness of the resin base film is an average value of the distance from the convex portion of the first fine uneven surface to the bottom surface of the transparent resin layer of the lowest layer, It measured using the Nikon contact-type film thickness meter "DEGIMICRO MS 5C". Similarly, the thickness of the antiglare film is an average value of the distance from the convex portion of the second fine uneven surface to the bottom surface of the lowermost transparent resin layer, and was measured using the same apparatus. The thickness of the hard coat layer was determined as the difference between the thickness of the antiglare film and the thickness of the resin base film.

(3) Measurement of optical properties of antiglare film (3-1) Haze The internal haze of the resin base film was measured as follows. First, the resin substrate film is bonded to a glass substrate using an optically transparent adhesive so that the surface opposite to the first fine uneven surface is on the glass substrate side, A triacetyl cellulose film (TAC film) having a haze of approximately 0% was bonded onto the fine irregular surface of 1 using glycerin. About the resin base film to which this TAC film was bonded, the haze value measured using a haze meter “HM-150” manufactured by Murakami Color Research Laboratory Co., Ltd. based on JIS K 7136 was used as the resin base film. The internal haze of the film was used.

  The surface haze and internal haze of the hard coat layer were measured as follows. First, after forming a hard coat layer on a resin base film to produce an anti-glare film, the anti-glare film and the glass substrate are pasted using a transparent adhesive so that the resin base film side becomes the bonding surface. The haze measured in accordance with JIS K 7136 was defined as the “overall haze” of the antiglare film. Next, a triacetyl cellulose film having a haze of almost 0 is bonded to the second fine uneven surface of the hard coat layer using glycerin, and the haze measured according to JIS K 7136 is applied to the antiglare film. "Internal haze". Based on the above formulas (1) and (2), the surface haze and internal haze of the hard coat layer were calculated from the obtained haze value and internal haze of the resin base film.

(3-2) Transmission / scattering profile The anti-glare film is bonded to a glass substrate so that the uneven surface is the surface, and from the direction inclined at a predetermined angle with respect to the film normal on the glass surface side, He-Ne. Parallel light from the laser was irradiated, and the transmitted scattered light intensity in the film normal direction was measured on the antiglare film uneven surface side. For the measurement of transmitted scattered light intensity, “3292 03 Optical Power Sensor” and “3292 Optical Power Meter” manufactured by Yokogawa Electric Corporation were used.

(3-3) Reflection profile Irradiation of parallel light from a He-Ne laser to a concavo-convex surface of an antiglare film from a direction inclined by 30 ° with respect to the film normal, and in a plane including the film normal and the irradiation direction The angle change of reflectance was measured. In the measurement of reflectance, both “3292 03 optical power sensor” and “3292 optical power meter” manufactured by Yokogawa Electric Corporation were used.

(3-4) Transmission Visibility The transmission clarity of the antiglare film was measured using an image clarity measuring device “ICM-1DP” manufactured by Suga Test Instruments Co., Ltd. based on JIS K 7105. Also in this case, in order to prevent the sample from warping, it was subjected to measurement after being bonded to a glass substrate using an optically transparent adhesive so that the concavo-convex surface became the surface. In this state, light was incident from the glass side and measurement was performed. The measured value here is a total value of values measured using four types of optical combs in which the widths of the dark part and the bright part are 0.125 mm, 0.5 mm, 1.0 mm, and 2.0 mm, respectively. . In this case, the maximum value of the transmission clarity is 400%.

(3-5) Reflection sharpness Using the same image clarity measuring device “ICM-1DP” as above, the reflection sharpness of the antiglare film was measured. Also in this case, in order to prevent the sample from warping, it was subjected to measurement after being bonded to a glass substrate using an optically transparent adhesive so that the concavo-convex surface became the surface. Further, in order to prevent reflection from the back glass surface, a 2 mm thick black acrylic resin plate is adhered to the glass surface of the glass plate on which the antiglare film is pasted, and attached in this state. The measurement was performed with light incident from the side. The measured value here is a total value of values measured using three types of optical combs in which the widths of the dark part and the bright part are 0.5 mm, 1.0 mm, and 2.0 mm, respectively (maximum value 300 %).

(4) Evaluation of anti-glare performance of anti-glare film (4-1) Visual evaluation of reflection, whitishness and texture In order to prevent reflection from the back surface of the anti-glare film, the uneven surface becomes the surface. An anti-glare film was bonded to a black acrylic resin plate and visually observed from the uneven surface side in a bright room with a fluorescent lamp, and the presence or absence of reflection of the fluorescent lamp, the degree of whiteness and the texture were visually evaluated. . Reflection, whitishness and texture were evaluated according to the following criteria in three stages of 1 to 3, respectively.
(A) Reflection; 1: Reflection is not observed. 2: Reflection is slightly observed. 3: Reflection is clearly observed.
(B) Whiteness; 1: Whiteness is not observed. 2: A little whitish is observed. 3: The whitish is clearly observed.
(C) Texture; 1: Fine eyes and good texture. 2: The eyes are slightly rough and the texture is a little bad. 3: The eyes are clearly rough and the texture is poor.

(4-2) Evaluation of glare The glare was evaluated by the following method. That is, first, a photomask having a unit cell pattern as shown in a plan view in FIG. 7 was prepared. In this figure, in the unit cell 700, a key-shaped chrome light shielding pattern 701 having a line width of 10 μm is formed on a transparent substrate, and a portion where the chrome light shielding pattern 701 is not formed is an opening 702. Here, the unit cell 700 has a size of 254 μm × 84 μm (vertical × horizontal in the figure), and thus the opening 702 has a dimension of 244 μm × 74 μm (vertical × horizontal in the figure). A large number of unit cells 700 shown in the figure are arranged vertically and horizontally to form a photomask.

Then, as shown in a schematic cross-sectional view in FIG. 8, the chrome light-shielding pattern 701 of the photomask 703 is placed on the light box 705, and the antiglare film 801 is coated with the adhesive on the glass plate 707 with the uneven surface on the surface. The sample bonded so as to become is placed on the photomask 703. A light source 706 is disposed in the light box 705. In this state, visual observation was performed at a position 709 that is about 30 cm away from the sample. The degree of glare was evaluated according to the following criteria in three stages of 1 to 3.
Glitter; 1: Glitter is not recognized. 2: Very slight glare is observed. 3: Severe glare is observed.

<Example 1>
(A) Production of Resin Base Film An acrylic resin containing 30 parts by weight of acrylic rubber particles in 70 parts by weight of a copolymer of methyl methacrylate / methyl acrylate = 96/4 (weight ratio) (refractive index 1.49). System resin composition and methyl methacrylate / styrene copolymer beads (refractive index 1.505, weight average particle diameter 8 μm) so that the beads are 30 parts by weight with respect to 100 parts by weight of the acrylic resin composition. After mixing with a Henschel mixer, the mixture was melt-kneaded with a first extruder (screw diameter 65 mm, uniaxial, vented (manufactured by Toshiba Machine Co., Ltd.)) and supplied to the feed block. In addition, an acrylic resin composition in which 30 parts by weight of acrylic rubber particles is contained in 70 parts by weight of a copolymer (refractive index 1.49) of methyl methacrylate / methyl acrylate = 96/4 (weight ratio) is the second. Were melt-kneaded with an extruder (screw diameter: 45 mm, uniaxial, with vent (manufactured by Hitachi Zosen)), and supplied to the feed block. Co-extrusion molding is performed at 265 ° C. so that the resin supplied to the feed block from the first extruder becomes a light diffusion layer and the resin supplied to the feed block from the second extruder becomes a transparent resin layer, A resin base film having a two-layer structure with a thickness of 80 μm (light diffusion layer 30 μm, transparent resin layer 50 μm) was produced through a roll unit set at 85 ° C.

(B) Production of antiglare film An ultraviolet curable resin composition in which the following components were dissolved in ethyl acetate at a solid content concentration of 60% was prepared.

60 parts of pentaerythritol triacrylate 40 parts of polyfunctional urethanized acrylate (reaction product of hexamethylene diisocyanate and pentaerythritol triacrylate)
Next, with respect to 100 parts by weight of the solid content of this ultraviolet curable resin composition, “Lucirin TPO” (manufactured by BASF, chemical name: 2,4,6-trimethylbenzoyldiphenylphosphine oxide) ) Was added in an amount of 5 parts by weight to prepare a coating solution.

This coating solution was applied to the surface of the light diffusion layer of the resin substrate film with No. It was applied at a coating speed of 2.0 mm / sec with a bar coater using a 2-wire bar, and dried for 1 minute in a dryer set at 80 ° C. From the UV curable resin composition layer side of the dried film, a fusion “D bulb” lamp (maximum emission wavelength 380 nm) is used as a light source, and the integrated light quantity becomes 1720 mJ / cm ² at an illuminance of 985 mW / cm ^2. And a UV curable resin composition layer is cured to form a laminate of a hard coat layer (cured resin layer) having a second fine irregular surface and a thickness of 2.4 μm and a resin base film. An antiglare film was obtained.

<Example 2>
Lamination of a hard coat layer having a thickness of 6.1 μm and a resin base film in the same manner as in Example 1 except that the coating liquid coating conditions for forming the hard coat layer were changed as shown in Table 1. An antiglare film consisting of a body was produced.

<Example 3>
Except that the addition amount of methyl methacrylate / styrene copolymer resin particles dispersed in the light diffusion layer of the resin base film and the coating liquid coating conditions when forming the hard coat layer are changed as shown in Table 1. Produced an antiglare film comprising a laminate of a hard coat layer having a thickness of 1.6 μm and a resin base film in the same manner as in Example 1.

<Example 4>
Lamination of a hard coat layer having a thickness of 3.8 μm and a resin base film in the same manner as in Example 3 except that the coating liquid coating conditions for forming the hard coat layer were changed as shown in Table 1. An antiglare film consisting of a body was produced.

<Example 5>
Particle size of methyl methacrylate / styrene copolymer resin particles dispersed in the light diffusing layer of the resin base film (meaning weight average particle size; the same applies hereinafter) and coating liquid application when forming a hard coat layer An antiglare film made of a laminate of a hard coat layer having a thickness of 1.6 μm and a resin substrate film was produced in the same manner as in Example 1 except that the conditions were changed as shown in Table 1.

<Example 6>
The particle diameter and addition amount of methyl methacrylate / styrene copolymer resin particles dispersed in the light diffusion layer of the resin base film and the coating liquid coating conditions when forming the hard coat layer were changed as shown in Table 1. Except for this, an antiglare film comprising a laminate of a hard coat layer having a thickness of 1.8 μm and a resin base film was produced in the same manner as in Example 1.

<Comparative Example 1>
The resin base film has a three-layer structure of transparent resin layer (thickness 25 μm) / light diffusion layer (thickness 30 μm) / transparent resin layer (thickness 25 μm), and coating liquid coating when forming a hard coat layer An antiglare film comprising a laminate of a hard coat layer having a thickness of 1.3 μm and a resin base film was produced in the same manner as in Example 1 except that the conditions were changed as shown in Table 1.

<Comparative Examples 2 and 3>
Table 1 shows the refractive index and particle size of the methyl methacrylate / styrene copolymer resin beads dispersed in the light diffusion layer of the resin base film, and the coating liquid coating conditions for forming the hard coat layer. Except having changed, it carried out similarly to Example 1, and produced the glare-proof film which consists of a laminated body of the hard-coat layer and resin base film whose thickness is shown in Table 1.

<Comparative Examples 4 and 5>
Table 1 shows the refractive index and particle size of the methyl methacrylate / styrene copolymer resin beads dispersed in the light diffusion layer of the resin base film, and the coating liquid coating conditions for forming the hard coat layer. An antiglare film comprising a laminate of a hard coat layer and a resin substrate film having a thickness as shown in Table 2 was produced in the same manner as in Example 1 except that the change was made.

  FIG. 9 shows the angle dependence of the scattered light intensity obtained by the measurement of the scattered light intensity for the antiglare films of Examples 1 to 6 (graph of the transmission scattering profile), and FIG. 9 shows the angle dependence of the reflected light obtained by the reflectance measurement. FIG. 10 shows the property (graph of reflection profile). Similarly, FIGS. 11 and 12 are a graph of a transmission / scattering profile and a graph of a reflection profile for the antiglare films of Comparative Examples 1 to 3, respectively. 13 and 14 are a graph of a transmission / scattering profile and a graph of a reflection profile for the antiglare films of Comparative Examples 4 and 5, respectively.

  Moreover, about the anti-glare film of the said Examples 1-6 and Comparative Examples 1-5, (I) Manufacturing conditions of an anti-glare film, (II) Surface shape of a resin base film (The shape of the 1st fine uneven surface) ), (III) Optical characteristics of antiglare film, and (IV) Surface shape of antiglare film (shape of second fine uneven surface) and antiglare performance are summarized in Tables 1 to 4, respectively. The breakdown of the reflection definition and transmission definition of the antiglare film of Example 1 shown in Table 3 is as follows.

Transmission sharpness Reflection sharpness 0.125 mm Optical comb: 0.4% −
0.5mm optical comb: 7.5% 3.0%
1.0 mm optical comb: 36.9% 3.4%
2.0mm optical comb: 71.1% 12.2%
Total 115.9% 18.6%

  As shown in Tables 1 to 4, the anti-glare films of Examples 1 to 6 show excellent anti-glare performance, do not cause glare and whitishness, and have reduced contrast when applied to an image display device. The causal relative scattered light intensities T (20) and T (30) also showed good scattering characteristics sufficiently low.

On the other hand, since the antiglare film of Comparative Example 1 has a small arithmetic average height Pa ₁ of the first fine uneven surface of the resin base film, the arithmetic average height of the second fine uneven surface of the hard coat layer is low. It was too small Pa ₂ , and sufficient antiglare property could not be obtained.

Further, in the antiglare films of Comparative Examples 2 and 3, the arithmetic average height Pa ₁ of the first fine uneven surface of the resin base film is large, and the thickness of the hard coat layer is 1.8 μm. In the antiglare film, since the arithmetic average height Pa _{2 of} the second fine uneven surface is increased, the whitish occurs and the hard coat layer has a thickness of 6.8 μm. Since the average length PSm 2 of the fine uneven surface ₂ was increased, the image was reflected and the texture was remarkably deteriorated.

Although the anti-glare film of Comparative Example 4 uses the same resin base film as in Example 1, the thickness of the hard coat layer was small, so that the effect of smoothing the first fine uneven surface of the resin base film was achieved. As a result, the arithmetic average height Pa ₂ of the second fine concavo-convex shape of the obtained antiglare film was increased, and whitening occurred.

Moreover, although the anti-glare film of the comparative example 5 uses the resin base film similar to Example 5, since the thickness of the hard-coat layer was large, the arithmetic mean height Pa2 of the _2nd fine unevenness | corrugation surface was set. It became small and sufficient anti-glare property could not be obtained. The results of Examples 1 and 5 and Comparative Examples 4 and 5 show that the first fine uneven surface having an appropriate surface shape was formed, and hard coat layer formation conditions (for example, the composition of the coating solution and the coating solution) It is shown that an antiglare film having excellent reflection characteristics and good antiglare performance can be obtained by controlling the coating conditions and the like to form the second fine uneven surface having an appropriate surface shape. .

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  By disposing the antiglare film of the present invention on various displays such as a liquid crystal panel, a plasma display panel, a CRT display, and an organic EL display so that the antiglare film is closer to the viewing side than the image display element. It is possible to blur the reflected image without generating blurring and glare, and to provide excellent visibility.

It is a cross-sectional schematic diagram which shows the preferable example of the anti-glare film of this invention. Schematic representation of incident light direction and transmitted scattered light intensity measurement direction when measuring the scattered light intensity observed in the normal direction of the hard coat layer side when light is incident from the resin base film side of the antiglare film It is a perspective view shown in FIG. It is an example of the graph which plotted the relative scattered light intensity | strength (logarithmic scale) measured by changing the incident angle (phi) using the anti-glare film of this invention with respect to the incident angle. It is a figure which shows the relationship between relative scattered light intensity | strength T (20) and T (30), and contrast. It is a perspective view which shows typically the incident direction and reflection direction of the light from the hard-coat layer side when calculating | requiring a reflectance. It is an example of the graph which plotted the relationship between the reflection angle of the reflected light with respect to the light which injected at the angle of 30 degrees from the normal line of the anti-glare film of this invention, and a reflectance (a reflectance is a logarithmic scale). It is a top view which shows the unit cell of the pattern for glare evaluation. It is a cross-sectional schematic diagram which shows the state at the time of glare evaluation. It is a graph showing the transmission-scattering profile of the anti-glare film obtained in Examples 1-6. It is a graph showing the reflection profile of the anti-glare film obtained in Examples 1-6. It is a graph showing the transmission-scattering profile of the anti-glare film obtained in Comparative Examples 1-3. It is a graph showing the reflection profile of the anti-glare film obtained in Comparative Examples 1-3. It is a graph showing the transmission-scattering profile of the anti-glare film obtained in Comparative Examples 4 and 5. It is a graph showing the reflection profile of the anti-glare film obtained in Comparative Examples 4 and 5.

Explanation of symbols

  101a, 101b Resin base film, 102a, 102b Hard coat layer, 103a, 103b Light diffusion layer, 104a, 104b Transparent resin layer, 105a, 105b Fine particles, 110a, 110b First fine uneven surface, 120a, 120b Second Fine uneven surface, 201,501,801 Antiglare film, 202,502 Normal line of antiglare film, 203 Incident light at angle of φ from normal, 204 Transmitted scattered light transmitted in normal direction, 209, 509 A plane including the incident light direction and the normal of the antiglare film, 505 Light incident at an angle of 30 °, 506 Regular reflection direction, 507 Light reflected at a reflection angle θ, 700 Photomask unit cell, 701 Photo Chrome light shielding pattern of mask, 702 photomask opening, 703 photomask, 705 Observation position of light box, 706 light source, 707 glass plate, 709 glare.

Claims (9)

A resin base film having a multilayer structure including at least one transparent resin layer made of a transparent resin, and at least one light diffusion layer containing fine particles having a refractive index different from that of the transparent binder resin and the transparent binder resin;
A hard coat layer laminated on the resin base film surface,
The hard coat layer side surface in the resin base film is composed of a first fine uneven surface having a fine uneven shape, and the arithmetic average height Pa ₁ of the first fine uneven surface is 0.4 μm or more and 2 μm or less. The average length PSm ₁ is 2 μm or more and 40 μm or less,
The surface of the hard coat layer opposite to the resin substrate film side is composed of a second fine uneven surface having a fine uneven shape, and the arithmetic average height Pa ₂ of the second fine uneven surface is 0. .2 μm or more and 0.6 μm or less, the average length PSm ₂ is 20 μm or more and 100 μm or less, and
The arithmetic average height Pa ₂ of the _second fine uneven surface is an antiglare film smaller than the arithmetic average height Pa _{1 of} the first fine uneven surface. The resin base film has an internal haze of 5% to 30%,
The antiglare film according to claim 1, wherein the hard coat layer has an internal haze of 2% or less and a surface haze of 0.5% or more and 15% or less. The thickness of the resin base film is 30 μm or more and 250 μm or less,
The antiglare film according to claim 1 or 2, wherein the hard coat layer has a thickness of 1 µm or more and 10 µm or less.   The antiglare film according to any one of claims 1 to 3, wherein each of the transparent resin and the transparent binder resin is an acrylic resin. The resin base film has a two-layer structure of one transparent resin layer and one light diffusion layer laminated on the surface of the transparent resin layer,
The anti-glare film according to any one of claims 1 to 4, wherein the hard coat layer is disposed on a surface of the light diffusion layer opposite to the transparent resin layer.   The anti-glare film according to any one of claims 1 to 4, wherein the resin base film has a three-layer structure including two transparent resin layers and a light diffusion layer disposed between the two transparent resin layers. .   The anti-glare film according to any one of claims 1 to 6, further comprising a low reflection film on the second fine uneven surface of the hard coat layer. An antiglare polarizing plate formed by laminating the antiglare film according to any one of claims 1 to 7 and a polarizing film,
The polarizing film is an antiglare polarizing plate arranged on the resin base film side of the antiglare film. An antiglare film according to any one of claims 1 to 7 or an antiglare polarizing plate according to claim 8, and an image display element,
The antiglare film or the antiglare polarizing plate is an image display device arranged on the viewing side of the image display element with the hard coat layer side facing outside.

Images