JP6314384B2 - Optical laminate, polarizing plate, and image display device - Google Patents

Description

The present invention relates to an optical laminate, a polarizing plate, and an image display device.

In image display devices such as cathode ray tube display (CRT), liquid crystal display (LCD), plasma display (PDP), electroluminescence display (ELD), field emission display (FED), antireflection performance, antistatic performance, hardware There is provided an optical laminate composed of functional layers having various performances such as coating properties and antifouling properties.

Such an optical laminate is formed by laminating various optical functional layers on a light-transmitting substrate. For this reason, for example, when a hard coat layer is formed on a light transmissive substrate, the reflected light at the interface between the light transmissive substrate and the hard coat layer interferes with the reflected light on the hard coat surface. Due to the unevenness of the film thickness, a nonuniform pattern called interference fringes appears and the appearance is impaired.

In order to prevent the occurrence of such interference fringes, for example, when a hard coat layer is formed on a light transmissive substrate, the resin composition for forming the hard coat layer penetrates into the light transmissive substrate. It is known to use a solvent that can swell or dissolve (see, for example, Patent Documents 1 and 2). By using such a resin composition containing a solvent, an impregnation layer in which the resin in the resin composition is impregnated in the light transmissive substrate is formed as the solvent penetrates the light transmissive substrate. As a result, the interface between the light transmissive substrate and the hard coat layer can be substantially eliminated, and the generation of interference fringes can be prevented.

However, in the conventional optical layered body in which interference fringes are prevented by forming such an impregnation layer, the impregnation layer must be formed thick in order to sufficiently prevent the occurrence of interference fringes. It was necessary to increase the coating amount of the composition used when forming the hard coat layer.
For this reason, there is a problem that it is difficult to reduce the thickness of the optical layered body or curl occurs, and if the composition at the time of forming the hard coat layer is increased, the thickness of the hard coat layer to be formed may be uneven. In addition, there is a problem that the manufacturing cost is high.
Furthermore, as an optical laminate used on the surface of an image display device, an optical laminate (antiglare film) provided with an antiglare property by providing an antiglare layer having an uneven shape on the surface on a light-transmitting substrate. ) Is also known. However, such an anti-glare film has a problem that even if the generation of interference fringes can be prevented, a cloudiness is generated and the contrast of the display image is lowered.

JP 2003-131007 A JP 2003-205563 A

In view of the above-mentioned present situation, the present invention is capable of sufficiently suppressing the generation of interference fringes and curls, without generating a cloudiness, and making it possible to reduce the thickness of the optical functional layer, thereby preventing an increase in manufacturing cost. It is an object of the present invention to provide an optical laminate that can be used, a polarizing plate using the optical laminate, and an image display device.

The present invention is an optical laminate having an optical functional layer having a concavo-convex shape on one surface of a light-transmitting substrate, wherein the optical functional layer contains silica fine particles, and the silica fine particles are In the cross section of the optical functional layer in the thickness direction of the optical functional layer, a region including a portion where the silica fine particles are distributed in a three-dimensional network is formed in the optical functional layer. The area of the silica fine particles when the area of 2 μm square is selected so that the area ratio of the silica fine particles in the area of 2 μm square is maximized from the observation screen under the condition of 10,000 times magnification with a microscope. rate is state, and are more than 30%, unevenness of the surface of the optical function layer has an average inclination angle θa of the uneven portion is an optical laminate and satisfies the following expression.
0.01 ° ≦ θa ≦ 0.09 °

Further, in the uneven shape on the surface of the optical functional layer, it is preferable that the absolute value of the Sk satisfies the following expression, where Sk is the unevenness skewness .
| Sk | ≦ 0.5
Moreover, it is preferable that the uneven | corrugated shape of the said optical function layer satisfy | fills the following formula | equation, when the arithmetic mean roughness of an unevenness | corrugation is set to Ra.
0.02 μm ≦ Ra ≦ 0.10 μm
Moreover, as for the uneven | corrugated shape of the said optical function layer, it is preferable that the average wavelength (lambda) a represented by (lambda) = 2 (pi) * (Ra / tan ((theta) a)) satisfy | fills a following formula.
200 μm ≦ λa ≦ 800 μm
The optical functional layer is preferably a hard coat layer.
Moreover, it is preferable that the said optical laminated body is a structure where the low-refractive-index layer was laminated | stacked on the hard-coat layer.

This invention is also a polarizing plate provided with a polarizing element, Comprising: The said polarizing plate is a polarizing plate characterized by providing the above-mentioned optical laminated body on the polarizing element surface.
The present invention is also an image display device including the above-described optical layered body or the above-described polarizing plate.
The present invention is described in detail below.
In the present invention, unless otherwise specified, curable resin precursors such as monomers, oligomers, and prepolymers are also referred to as “resins”.

As a result of intensive studies on an optical laminate having an optical functional layer on one surface of a light-transmitting substrate, the present inventors have found that silica fine particles have a certain amount of capillaries in the optical functional layer. By forming and including it, and forming an extremely gentle sloped irregular shape on the surface of the optical functional layer, it is possible to reduce the thickness of the optical functional layer while sufficiently suppressing the occurrence of interference fringes and curls. The inventors have found that the production cost can be prevented and have completed the present invention.
Conventionally, for the purpose of imparting antiglare properties, an optical laminate (antiglare film) having a concavo-convex shape on the surface of the optical functional layer is known, but the optical laminate of the present invention has such an antiglare property. It is different from a dazzling film. That is, the concavo-convex shape formed on the surface of the optical functional layer of the optical laminate of the present invention has a lower concavo-convex height than the concavo-convex shape formed on the surface of the conventional antiglare film, The inclination angle of the uneven part is smoother. Therefore, in the optical layered body of the present invention in which such an uneven shape is formed in the optical functional layer, the antiglare property as in the conventional antiglare film cannot be obtained. On the other hand, according to the present invention, it is possible to obtain an optical laminate that provides an image with excellent contrast without causing the occurrence of white turbidity due to external light, which is a problem with anti-glare films.

This invention is an optical laminated body which has the optical function layer which has an uneven | corrugated shape on the surface on one surface of a transparent base material.
The light transmissive substrate preferably has smoothness and heat resistance and is excellent in mechanical strength. Specific examples of the material forming the light-transmitting substrate include, for example, polyester (polyethylene terephthalate, polyethylene naphthalate), cellulose triacetate, cellulose diacetate, cellulose acetate butyrate, polyester, polyamide, polyimide, polyethersulfone, poly Examples thereof include thermoplastic resins such as sulfone, polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyether ketone, polymethyl methacrylate, polycarbonate, and polyurethane, and glass. Preferably, polyester (polyethylene terephthalate, polyethylene naphthalate) and cellulose triacetate are used.

The light-transmitting substrate is preferably used as a flexible film-like material, but a plate-like material may be used depending on the use mode in which curability is required. .

In addition, examples of the light transmissive substrate include an amorphous olefin polymer (Cyclo-Olefin-Polymer: COP) film having an alicyclic structure. This is a base material in which a norbornene polymer, a monocyclic olefin polymer, a cyclic conjugated diene polymer, a vinyl alicyclic hydrocarbon polymer, and the like are used. Zeonoa (norbornene-based resin), Sumitrite FS-1700 manufactured by Sumitomo Bakelite, Arton (modified norbornene-based resin) manufactured by JSR, Appel (cyclic olefin copolymer) manufactured by Mitsui Chemicals, Topas (cyclic) manufactured by Ticona Olefin copolymer), Optretz OZ-1000 series (alicyclic acrylic resin) manufactured by Hitachi Chemical Co., Ltd., and the like.
Further, the FV series (low birefringence, low photoelastic modulus film) manufactured by Asahi Kasei Chemicals is also preferable as an alternative base material for triacetylcellulose.

In the case of a film-like body, the thickness of the light transmissive substrate is preferably 20 to 300 μm, more preferably the lower limit is 30 μm and the upper limit is 200 μm. When the light-transmitting substrate is a plate-like body, the thickness may exceed these thicknesses.
The light-transmitting substrate has an anchor agent or primer in addition to a physical or chemical treatment such as corona discharge treatment or oxidation treatment in order to improve adhesion when the hard coat layer is formed thereon. Application | coating of a coating called may be performed previously.
In addition, when triacetylcellulose, which is often used mainly as a light-transmitting substrate for LCD, is used as a material and a display thin film is desired, the thickness of the light-transmitting substrate is preferably 20 to 65 μm. .

In the optical layered body of the present invention, the optical functional layer contains silica fine particles in a specific state distributed in a capillary shape.
Since the silica fine particles are contained in the optical functional layer in such a specific state, the surface of the optical functional layer is formed with an extremely gentle uneven shape, and interference fringes and curls are sufficiently generated. It is possible to reduce the thickness of the optical functional layer while preventing the manufacturing cost from increasing.

In the optical layered body of the present invention, the silica fine particles are distributed in a capillary shape in the optical functional layer.
In such an optical layered body of the present invention, the silica fine particles are observed in a certain amount of capillaries when the cross section in the thickness direction of the optical functional layer is observed. In addition, “capillary” means that the silica fine particles are distributed as a mass having a certain interval in a bridge shape, rather than forming an aggregate in which the silica fine particles are closely aggregated. In other words, for example, it can be said that the silica fine particles are distributed in the optical functional layer in a lump that spreads to some extent in a three-dimensional network.

Further, in the cross section in the thickness direction of the optical functional layer, an area including a portion where the silica fine particles are distributed in a capillary shape is selected with an electron microscope (preferably a transmission type. For example, S-4800 manufactured by Hitachi High-Tech Co., Ltd. The area when the area of 2 μm square is selected so that the area ratio of the silica fine particles in the area of 2 μm square is maximized from the observation screen. The rate (hereinafter also referred to as the maximum area rate) is 30% or less. When the maximum area ratio exceeds 30%, the silica fine particles are densely aggregated and are not sufficiently distributed in the shape of capillaries, which causes whitening of the optical functional layer. A preferable upper limit of the maximum area ratio is 25%, and a more preferable upper limit is 20%. The preferable lower limit of the maximum area ratio is 5%. When the maximum area ratio is less than 5%, it may not be possible to form an uneven shape on the surface of the optical functional layer that can sufficiently suppress the generation of interference fringes.
The area ratio can be calculated from a photograph taken with the electron microscope by image processing software (for example, Image-Pro Plus manufactured by Media Cybernetics, etc. is preferably used).

Further, when the region including the portion in which the silica fine particles are distributed in the shape of capillaries in the cross section in the thickness direction of the optical functional layer is observed with an electron microscope at a magnification of 10,000, the silica fine particle aggregates Is regarded as one particle, the aspect ratio of the aggregate is 2.0 or more. When the aspect ratio is less than 2.0, a sufficient capillary distribution is not formed, and the slope of the unevenness formed on the surface of the optical functional layer becomes steep and causes whitening. A preferable lower limit of the aspect ratio is 2.5, and a more preferable lower limit is 3.0.
The aspect ratio can be calculated from a photograph taken with the electron microscope using image processing software (for example, Image-Pro Plus manufactured by Media Cybernetics, etc. is preferably used).

In the optical layered body of the present invention, known materials can be used as the silica fine particles, and among these, fumed silica is preferable. Here, the fumed silica refers to amorphous silica having a particle size of 200 nm or less prepared by a dry method, and is obtained by reacting a volatile compound containing silicon in a gas phase. Specifically, for example, a silicon compound, for example, one produced by hydrolyzing SiCl ₄ in a flame of oxygen and hydrogen can be used. Since the fumed silica is less likely to form a dense aggregate as compared with precipitation silica or gel silica prepared by a wet method, it is preferable for distribution in a capillary shape in the optical functional layer. Specific examples of the fumed silica include AEROSIL R805 (manufactured by Nippon Aerosil Co., Ltd.). As the silica fine particles, colloidal silica is also preferably used because it is difficult to form a dense aggregate. The colloidal silica refers to amorphous silica obtained by synthesizing in the liquid phase by hydrolysis of alkoxysilane, and specific examples include Snow Tech manufactured by Nissan Chemical Co., Ltd.

The silica fine particles are preferably surface-treated. Since the silica fine particles are surface-treated, they can be suitably distributed in a capillary shape in the optical functional layer, and the chemical resistance and saponification resistance of the silica fine particles themselves can be improved. it can.
The surface treatment is preferably a hydrophobic treatment, and examples thereof include a method of treating the silica fine particles with a surface treatment agent such as a silane compound having a methyl group or octylsilane. Here, hydroxyl groups are usually present on the surface of the silica fine particles, but the surface treatment reduces the hydroxyl groups on the surface of the silica fine particles. Further, the type and treatment amount of the surface treatment agent are reduced. By adjusting, the ratio of the hydroxyl group on the surface of the silica fine particles can be adjusted. Thereby, the degree of aggregation of the types of silica fine particles can be controlled, and the above-described capillary distribution can be easily formed.

Although it does not specifically limit as content of the said silica fine particle, It is preferable that it is 0.1-5.0 mass% in the said optical function layer. If it is less than 0.1% by mass, it may not be able to be distributed in the form of capillaries in the optical functional layer. If it exceeds 5.0% by mass, whitening may occur in the optical functional layer. . A more preferable lower limit is 0.5% by mass, and a more preferable upper limit is 3.0% by mass.

The average primary particle diameter of the silica fine particles is preferably 1 to 200 nm. If it is less than 1 nm, it may not be able to be distributed in the form of capillaries in the optical function layer, and even if it exceeds 200 nm, it may not be able to be distributed in the form of capillaries in the optical function layer. A more preferred lower limit is 10 nm, and a more preferred upper limit is 50 nm.
The silica fine particles are preferably spherical in shape in a single particle state. Since the single particle of the silica fine particles is spherical, a high-contrast display image can be obtained when the optical layered body of the present invention is applied to an image display device.
In addition, the above “spherical” includes, for example, a true spherical shape, an elliptical spherical shape and the like, and has a meaning excluding so-called indefinite shape.

The optical functional layer preferably has a hard coat performance. For example, the hardness is preferably H or more in a pencil hardness test (load 4.9 N) according to JIS K5600-5-4 (1999). More preferably.

In the optical layered body of the present invention, the optical functional layer is formed on one surface of the light-transmitting substrate and has an uneven shape on the surface. When the optical functional layer has a concavo-convex shape on the surface, the optical laminate of the present invention can prevent occurrence of interference fringes.
As described above, the concavo-convex shape formed on the surface of the optical functional layer is such that the slope of the concavo-convex part is gentle compared to the slope of the concavo-convex part of the concavo-convex shape of the conventionally known anti-glare layer, In the optical layered body of the present invention, the concavo-convex shape formed on the surface of the optical functional layer has the following formula when θa and Sk have the average inclination angle of the concavo-convex part as θa and the skewness of the concavo-convex part as Sk. It is preferable to satisfy.
0.01 ° ≦ θa ≦ 0.10 °
| Sk | ≦ 0.5

The reason that the interference fringes can be prevented by the uneven shape formed on the surface of the optical functional layer is that light reflected on the surface of the optical functional layer diffuses and becomes non-interfering light. In order to diffuse light, the uneven surface needs to be inclined, and the index is the average inclination angle θa.
In the optical layered body of the present invention, the lower limit of the average inclination angle θa of the concavo-convex portion is preferably 0.01 °. If it is less than 0.01 °, the inclination may not be sufficient and interference fringes may not be prevented. A more preferred lower limit is 0.03 °, and a still more preferred lower limit is 0.04 °. Moreover, it is preferable that the upper limit of the average inclination | tilt angle (theta) a of the said uneven | corrugated | grooved part is 0.10 degree. If the angle exceeds 0.10 °, the inclination angle of the concavo-convex portion is excessively large, which may cause a problem of cloudiness due to diffuse reflection of external light. A more preferred upper limit is 0.09 °, and a still more preferred upper limit is 0.08 °.

In the present invention, the absolute value of the unevenness skewness Sk is preferably 0.5 or less. The skewness Sk indicates that the larger the absolute value, the greater the asymmetry of the surface unevenness with respect to the average line. When the asymmetry of the surface irregularity shape is large, there are steep peak portions and gentle valley portions (when Sk> 0), and even if the average inclination angle θa satisfies the above range, the inclination angle distribution thereof Indicates that there is a bias. That is, the inclination angle of the peak portion is increased, and the inclination angle of the valley portion is decreased (when Sk <0, the relationship between the peak and the valley is reversed). In such a case, in a portion where the inclination angle is large, light diffusion is excessively increased, and there is a possibility that a cloudiness problem may occur. On the other hand, in a portion where the inclination angle is small, interference fringes may not be suitably prevented. If the absolute value of Sk is 0.5 or less, the asymmetry of the surface irregularity shape is small, so that the deviation of the inclination angle distribution can be moderately suppressed, and interference fringes can be suitably prevented. Can be suppressed. The absolute value of the Sk is more preferably 0.4 or less, and still more preferably 0.2 or less.

Moreover, in this invention, when the arithmetic mean roughness of an unevenness | corrugation is set to Ra, it is preferable to satisfy | fill the following formula | equation.
0.02 μm ≦ Ra ≦ 0.10 μm
In the present invention, it is preferable to control the size (height) of each convex and concave portion, but the index is the arithmetic average roughness Ra.
The minimum with preferable arithmetic mean roughness Ra of the said unevenness | corrugation is 0.02 micrometer. When the Ra is less than 0.02 μm, the size (height) of each convex portion is too small with respect to the wavelength of light, and the diffusion effect may not be obtained. A more preferred lower limit is 0.03 μm, and a still more preferred lower limit is 0.04 μm. The preferable upper limit of Ra is 0.10 μm. When Ra is more than 0.10 μm, each convex portion becomes too large and the transmitted light is distorted, so that a clear image may not be obtained. A more preferred upper limit is 0.09 μm, and a still more preferred upper limit is 0.08 μm.

In the present invention, the average wavelength λa represented by λa = 2π × (Ra / tan (θa)) is preferably 200 μm or more and 800 μm or less.
The average wavelength λa is a parameter indicating the average interval between the irregularities. If the average wavelength λa is less than 200 μm, the unevenness is too small to prevent interference fringes, or the change in the inclination angle on the uneven surface is too large, and there is a fear that a cloudiness may be seen. If the average wavelength λa exceeds 800 μm, the change in the inclination angle on the uneven surface is reduced, and there is a possibility that interference fringes cannot be prevented suitably. A more preferable lower limit of the average wavelength λa is 300 μm, and a more preferable upper limit is 600 μm.

Moreover, it is preferable that the ten-point average roughness (Rz) of the concavo-convex shape formed on the surface of the optical functional layer is less than 0.5 μm, and a more preferable upper limit is 0.3 μm. If the Rz is 0.5 μm or more, the unevenness is too large and a cloudiness may be observed. The lower limit of Rz is not particularly limited, and is appropriately adjusted within a range where a diffusion effect can be obtained.

In the present specification, the above θa, Sk, Ra, and Rz are values obtained for each reference length from a roughness curve obtained by a method according to JIS B 0601-1994. Ra and Rz are values defined in JIS B 0601-1994, and θa is described in a surface roughness measuring instrument: SE-3400 instruction manual (revised 1995.07.20) (Kosaka Laboratory Ltd.) As shown in FIG. 1, the arc tangent θa = tan ⁻¹ {(the sum (h ₁ + h ₂ + h ₃ +... + H _n ) of the heights of the convex portions existing in the reference length L. h ₁ + h ₂ + h ₃ +... + h _n ) / L}.
The Sk is a value defined by the following equation.
Here, l represents a reference length, f (x) represents a roughness curve, Rq is a root mean square roughness, and is defined by the following equation.
Such θa, Sk, Ra, and Rz can be determined by measuring with, for example, a surface roughness measuring instrument: SE-3400 / manufactured by Kosaka Laboratory Ltd.

In the optical layered body of the present invention, the optical functional layer is preferably a hard coat layer.
The thickness of the hard coat layer is preferably 2.0 to 7.0 μm. If it is less than 2.0 μm, the surface of the hard coat layer may be easily damaged, and if it exceeds 7.0 μm, not only the hard coat layer cannot be thinned, but also the hard coat layer tends to break, Curling can be a problem. A more preferable range of the thickness of the hard coat layer is 2.0 to 5.0 μm. In addition, the thickness of the said hard-coat layer can be measured by cross-sectional microscope observation.

In the hard coat layer, the silica fine particles are preferably dispersed in a binder resin.
As the binder resin, for example, the polarity is preferably adjusted according to the hydrophobicity of the hydrophobized silica fine particles. Examples of the method for adjusting the polarity of the binder resin include adjusting the hydroxyl value of the binder resin. By optimizing the polarity of the binder resin, the aggregation / dispersibility of the silica fine particles is suitably controlled, and the above-described capillary blood vessels are easily distributed in the optical functional layer.

As said binder resin, a transparent thing is preferable, for example, it is preferable that the ionizing radiation hardening type resin which is resin hardened | cured by an ultraviolet-ray or an electron beam hardens | cures by irradiation of an ultraviolet-ray or an electron beam.

Examples of the ionizing radiation curable resin include compounds having one or more unsaturated bonds such as compounds having functional groups such as acrylates. Examples of the compound having one unsaturated bond include ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, methylstyrene, N-vinylpyrrolidone and the like. Examples of the compound 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, and 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 Rate, 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 Polyfunctional compounds such as tetra (meth) acrylate, adamantyl di (meth) acrylate, isoboronyl di (meth) acrylate, dicyclopentane di (meth) acrylate, tricyclodecane di (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate Etc. Of these, pentaerythritol tetraacrylate (PETTA) is preferably used. In the present specification, “(meth) acrylate” refers to methacrylate and acrylate. In the present invention, as the ionizing radiation curable resin, a compound obtained by modifying the above-described compound with PO, EO or the like can also be used.

In addition to the above compounds, relatively low molecular weight polyester resins having unsaturated double bonds, polyether resins, acrylic resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, etc. It can be used as an ionizing radiation curable resin.

The ionizing radiation curable resin is used in combination with a solvent-drying resin (a thermoplastic resin or the like, which is a resin that forms a film only by drying the solvent added to adjust the solid content during coating). You can also. By using the solvent-drying resin in combination, film defects on the coating surface of the coating liquid can be effectively prevented when forming the hard coat layer.
The solvent-drying resin that can be used in combination with the ionizing radiation curable resin is not particularly limited, and a thermoplastic resin can be generally used.
The thermoplastic resin is not particularly limited. For example, a styrene resin, a (meth) acrylic resin, a vinyl acetate resin, a vinyl ether resin, a halogen-containing resin, an alicyclic olefin resin, a polycarbonate resin, or a polyester resin. Examples thereof include resins, polyamide-based resins, cellulose derivatives, silicone-based resins, rubbers, and elastomers. The 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 viewpoint of transparency and weather resistance, styrene resins, (meth) acrylic resins, alicyclic olefin resins, polyester resins, cellulose derivatives (cellulose esters, etc.) and the like are preferable.

The hard coat layer may contain a thermosetting resin.
The thermosetting resin is not particularly limited. For example, phenol resin, urea resin, diallyl phthalate resin, melamine resin, guanamine resin, unsaturated polyester resin, polyurethane resin, epoxy resin, aminoalkyd resin, melamine-urea cocondensation Examples thereof include resins, silicon resins, polysiloxane resins, and the like.

The hard coat layer containing the silica fine particles and the binder resin is prepared by, for example, applying the above-described silica fine particles, the hard coat layer composition containing the monomer component of the binder resin and the solvent onto the light-transmitting substrate and drying. It can be formed by curing the coating film formed by ionizing radiation irradiation or the like.

Examples of the solvent contained in the hard coat layer composition include alcohols (eg, methanol, ethanol, propanol, isopropanol, n-butanol, s-butanol, t-butanol, benzyl alcohol, PGME, ethylene glycol), ketones, and the like. (Acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.), ethers (dioxane, tetrahydrofuran, etc.), aliphatic hydrocarbons (hexane, etc.), alicyclic hydrocarbons (cyclohexane, etc.), aromatic hydrocarbons ( Toluene, xylene, etc.), halogenated carbons (dichloromethane, dichloroethane, etc.), esters (methyl acetate, ethyl acetate, butyl acetate, etc.), cellosolves (methyl cellosolve, ethyl cellosolve, etc.), cellosolve acetates, sulfo Sid compound (dimethylsulfoxide), amides (dimethylformamide, dimethylacetamide, etc.) and the like can be exemplified, or a mixture thereof.

The hard coat layer composition preferably further contains a photopolymerization initiator.
The photopolymerization initiator is not particularly limited, and known ones can be used. Specific examples include, for example, acetophenones, benzophenones, Michler benzoylbenzoate, α-amyloxime ester, thioxanthones, propio Examples include phenones, benzyls, benzoins, and acylphosphine oxides. In addition, it is preferable to use a mixture of photosensitizers, and specific examples thereof include n-butylamine, triethylamine, poly-n-butylphosphine, and the like.

As the photopolymerization initiator, when the binder resin is a resin system having a radical polymerizable unsaturated group, acetophenones, benzophenones, thioxanthones, benzoin, benzoin methyl ether, etc. may be used alone or in combination. preferable. When the binder resin is a resin system having a cationic polymerizable functional group, examples of the photopolymerization initiator include aromatic diazonium salts, aromatic sulfonium salts, aromatic iodonium salts, metallocene compounds, benzoin sulfonate esters, and the like. Are preferably used alone or as a mixture.

The content of the photopolymerization initiator in the hard coat layer composition is preferably 0.5 to 10.0 parts by mass with respect to 100 parts by mass of the binder resin. If the amount is less than 0.5 parts by mass, the hard coat performance of the hard coat layer to be formed may be insufficient. If the amount exceeds 10.0 parts by mass, there is a possibility of inhibiting curing. It is not preferable.

Although it does not specifically limit as a content rate (solid content) of the raw material in the said composition for hard-coat layers, Usually, it is preferable to set it as 5-70 mass%, especially 25-60 mass%.

In the hard coat layer composition, according to the purpose of increasing the hardness of the hard coat layer, suppressing curing shrinkage, controlling the refractive index, etc., conventionally known dispersants, surfactants, antistatic agents, Silane coupling agent, thickener, anti-coloring agent, coloring agent (pigment, dye), antifoaming agent, leveling agent, flame retardant, UV absorber, adhesion-imparting agent, polymerization inhibitor, antioxidant, surface modification An agent, a lubricant, etc. may be added.
As the leveling agent, for example, silicone oil, fluorine-based surfactant and the like are preferable because the hard coat layer is prevented from having a Benard cell structure. When a resin composition containing a solvent is applied and dried, a surface tension difference or the like is generated between the coating film surface and the inner surface in the coating film, thereby causing many convections in the coating film. The structure generated by this convection is called a Benard cell structure, and causes a problem such as the skin and coating defects in the hard coat layer to be formed.
Further, the Benard cell structure has a possibility that the irregularities on the surface of the hard coat layer become too large and the appearance of the optical laminate is impaired. When the leveling agent as described above is used, this convection can be prevented, so that not only a hard coat layer film free from defects and unevenness can be obtained, but also the uneven shape of the hard coat layer surface can be easily adjusted.

The method for preparing the hard coat layer composition is not particularly limited as long as each component can be uniformly mixed. For example, the composition can be performed using a known apparatus such as a paint shaker, a bead mill, a kneader, or a mixer.

The method for applying the hard coat layer composition onto the light-transmitting substrate is not particularly limited. For example, spin coating, dipping, spraying, die coating, bar coating, roll coater, meniscus coater And publicly known methods such as a method, a flexographic printing method, a screen printing method, and a pea coater method.
After applying the hard coat layer composition by any of the methods described above, the film is transported to a heated zone to dry the formed coating film, and the coating film is dried by various known methods to evaporate the solvent. Here, the distribution state of the silica fine particles can be adjusted by selecting the relative evaporation rate of the solvent, the solid content concentration, the coating solution temperature, the drying temperature, the wind speed of the drying air, the drying time, the solvent atmosphere concentration in the drying zone, and the like.
In particular, a method of adjusting the distribution state of silica fine particles in a capillary shape by selecting drying conditions is simple and preferable. The specific drying temperature is preferably 30 to 120 ° C., and the drying wind speed is preferably 0.2 to 50 m / s, and the silica fine particles are obtained by performing drying treatment appropriately adjusted within this range once or plural times. It is possible to adjust the distribution state in the capillary shape to a desired state.

In addition, as a method of irradiating ionizing radiation when curing the coating film after drying, for example, a light source such as an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc lamp, a black light fluorescent lamp, or a metal halide lamp is used. A method is mentioned.
Moreover, as a wavelength of an ultraviolet-ray, the wavelength range of 190-380 nm can be used. Specific examples of the electron beam source include various electron beam accelerators such as a cockcroft-wald type, a bandegraft type, a resonant transformer type, an insulated core transformer type, a linear type, a dynamitron type, and a high frequency type.

In addition, since the optical layered body of the present invention can reduce reflection from the surroundings and improve the transmittance, the optical functional layer has a structure in which a low refractive index layer is stacked on the hard coat layer. It is preferable that
In addition, when the optical laminated body of this invention has the said low refractive index layer on the said hard-coat layer as an optical function layer, the specific uneven | corrugated shape mentioned above may be formed in the surface of this low refractive index layer. is necessary.

The low refractive index layer is a layer that plays a role of reducing the reflectance when light from the outside (for example, a fluorescent lamp, natural light, etc.) is reflected on the surface of the optical laminate.
The low refractive index layer is preferably 1) a resin containing low refractive index particles such as silica and magnesium fluoride, 2) a fluorine-based resin which is a low refractive index resin, and 3) silica or magnesium fluoride. Fluorine-based resin, 4) A thin film of a low refractive index material such as silica or magnesium fluoride. For resins other than the fluorine-based resin, the same resin as the binder resin constituting the hard coat layer described above can be used.
Moreover, it is preferable that the silica mentioned above is a hollow silica fine particle, and such a hollow silica fine particle can be produced by, for example, a production method described in Examples of JP-A-2005-099778.
These low refractive index layers preferably have a refractive index of 1.45 or less, particularly 1.42 or less.
Further, the thickness of the low refractive index layer is not limited, but it may be set appropriately from the range of about 30 nm to 1 μm.
In addition, although the low refractive index layer is effective as a single layer, it is possible to provide two or more low refractive index layers as appropriate for the purpose of adjusting a lower minimum reflectance or a higher minimum reflectance. . When the two or more low refractive index layers are provided, it is preferable to provide a difference in the refractive index and thickness of each low refractive index layer.

As the fluororesin, a polymerizable compound containing a fluorine atom in at least a molecule or a polymer thereof can be used. Although it does not specifically limit as a polymeric compound, For example, what has hardening reactive groups, such as a functional group hardened | cured by ionizing radiation, and a polar group thermally cured, is preferable. Moreover, the compound which has these reactive groups simultaneously may be sufficient. In contrast to this polymerizable compound, a polymer has no reactive groups as described above.

As the polymerizable compound having a functional group that is cured by ionizing radiation, fluorine-containing monomers having an ethylenically unsaturated bond can be widely used. More specifically, to illustrate fluoroolefins (eg, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, perfluorobutadiene, perfluoro-2,2-dimethyl-1,3-dioxole, etc.) Can do. As those having a (meth) acryloyloxy group, 2,2,2-trifluoroethyl (meth) acrylate, 2,2,3,3,3-pentafluoropropyl (meth) acrylate, 2- (perfluorobutyl) ) Ethyl (meth) acrylate, 2- (perfluorohexyl) ethyl (meth) acrylate, 2- (perfluorooctyl) ethyl (meth) acrylate, 2- (perfluorodecyl) ethyl (meth) acrylate, α-trifluoro (Meth) acrylate compounds having a fluorine atom in the molecule, such as methyl methacrylate and α-trifluoroethyl methacrylate; a C 1-14 fluoroalkyl group having at least 3 fluorine atoms in the molecule, fluoro A cycloalkyl group or a fluoroalkylene group and at least two (medium There are also fluorine-containing polyfunctional (meth) acrylic acid ester compounds having an acryloyloxy group.

Preferable examples of the thermosetting polar group include hydrogen bond forming groups such as a hydroxyl group, a carboxyl group, an amino group, and an epoxy group. These are excellent not only in adhesion to the coating film but also in affinity with inorganic ultrafine particles such as silica. Examples of the polymerizable compound having a thermosetting polar group include 4-fluoroethylene-perfluoroalkyl vinyl ether copolymer; fluoroethylene-hydrocarbon vinyl ether copolymer; epoxy, polyurethane, cellulose, phenol, polyimide, and the like. Examples include fluorine-modified products of each resin.
Examples of the polymerizable compound having both a functional group curable by ionizing radiation and a polar group curable by heat include acrylic or methacrylic acid moieties and fully fluorinated alkyl, alkenyl, aryl esters, fully or partially fluorinated vinyl ethers, fully Alternatively, partially fluorinated vinyl esters, fully or partially fluorinated vinyl ketones and the like can be exemplified.

Moreover, as a fluorine resin, the following can be mentioned, for example.
Polymer of monomer or monomer mixture containing at least one fluorine-containing (meth) acrylate compound of a polymerizable compound having an ionizing radiation curable group; at least one fluorine-containing (meth) acrylate compound; and methyl (meth) Copolymers with (meth) acrylate compounds that do not contain fluorine atoms in the molecule such as acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate; fluoroethylene , Fluorine-containing compounds such as vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, 3,3,3-trifluoropropylene, 1,1,2-trichloro-3,3,3-trifluoropropylene, hexafluoropropylene Monomer homopolymer or Copolymer such as. Silicone-containing vinylidene fluoride copolymers obtained by adding a silicone component to these copolymers can also be used. The silicone components in this case include (poly) dimethylsiloxane, (poly) diethylsiloxane, (poly) diphenylsiloxane, (poly) methylphenylsiloxane, alkyl-modified (poly) dimethylsiloxane, azo group-containing (poly) dimethylsiloxane, Dimethyl silicone, phenylmethyl silicone, alkyl / aralkyl modified silicone, fluorosilicone, polyether modified silicone, fatty acid ester modified silicone, methyl hydrogen silicone, silanol group containing silicone, alkoxy group containing silicone, phenol group containing silicone, methacryl modified silicone, acrylic Modified silicone, amino modified silicone, carboxylic acid modified silicone, carbinol modified silicone, epoxy modified silicone, mercapto modified silicone Over emissions, fluorine-modified silicones, polyether-modified silicone and the like. Of these, those having a dimethylsiloxane structure are preferred.

Furthermore, non-polymers or polymers composed of the following compounds can also be used as the fluororesin. That is, a fluorine-containing compound having at least one isocyanato group in the molecule is reacted with a compound having at least one functional group in the molecule that reacts with an isocyanato group such as an amino group, a hydroxyl group, or a carboxyl group. Compound obtained: a compound obtained by reacting a fluorine-containing polyol such as fluorine-containing polyether polyol, fluorine-containing alkyl polyol, fluorine-containing polyester polyol, fluorine-containing ε-caprolactone modified polyol with a compound having an isocyanato group Can be used.

Moreover, each binder resin as described in the said hard-coat layer can also be mixed and used with the polymeric compound and polymer which have the above-mentioned fluorine atom. Furthermore, various additives and solvents can be used as appropriate in order to improve the curing agent for curing reactive groups and the like, to improve the coating property, and to impart antifouling properties.

In the formation of the low refractive index layer, the viscosity of the composition for low refractive index layer obtained by adding the above-mentioned material is 0.5 to 5 mPa · s (25 ° C.), preferably 0. It is preferable to set it as the thing of the range of 7-3 mPa * s (25 degreeC). An antireflection layer excellent in visible light can be realized, a uniform thin film with no coating unevenness can be formed, and a low refractive index layer particularly excellent in adhesion can be formed.

The resin curing means may be the same as that described for the hard coat layer described above. When a heating means is used for the curing treatment, it is preferable to add a thermal polymerization initiator that generates, for example, a radical by heating to start polymerization of the polymerizable compound, to the fluororesin composition.

The layer thickness (nm) d _A of the low refractive index layer is expressed by the following formula (1):
d _A = mλ / (4n _A ) (1)
(In the above formula,
n _A represents the refractive index of the low refractive index layer;
m represents a positive odd number, preferably 1;
λ is a wavelength, preferably a value in the range of 480 to 580 nm)
Those satisfying these conditions are preferred.

In the present invention, the low refractive index layer is represented by the following formula (2):
_{120 <n A d A <145} (2)
It is preferable from the viewpoint of low reflectivity.

The optical layered body of the present invention preferably has a total light transmittance of 90% or more. If it is less than 90%, color reproducibility and visibility may be impaired when the optical laminate of the present invention is mounted on the surface of an image display device. The total light transmittance is more preferably 91% or more.
In addition, the said total light transmittance can be measured by the method based on JISK-7361 using a haze meter (the product number; HM-150 by Murakami Color Research Laboratory).

The optical layered body of the present invention preferably has a total haze of less than 2.0%. If it is 2.0% or more, desired optical characteristics cannot be obtained, and the visibility when the optical laminate of the present invention is placed on the image display surface may be lowered. Preferably it is 1.5% or less, More preferably, it is 1.0% or less.
The total haze can be measured by a method based on JIS K-7136 using a haze meter (manufactured by Murakami Color Research Laboratory, product number: HM-150).

The optical layered body of the present invention preferably has a transmitted image definition of 75 to 95% for a 0.125 mm comb and 95% or more for a 2.0 mm comb. If the transmitted image definition of a 0.125 mm comb is less than 75%, the clarity of the image when the image is displayed may be impaired, and the image quality may be inferior. If it exceeds 95%, the interference fringes may not be suitably prevented. It is more preferable that the transmitted image definition in a 0.125 mm comb is 80 to 90%. Further, if the transmitted image definition in a 2.0 mm comb is less than 95%, the clarity of the image is impaired, and there is a risk that white turbidity due to diffuse reflection of external light may occur.
The transmission image definition can be measured by a method based on the image definition transmission method of JIS K-7105 using a image clarity measuring device (manufactured by Suga Test Instruments, product number: ICM-1T).

The optical layered body of the present invention preferably has a contrast ratio of 80% or more, more preferably 90% or more. If it is less than 80%, when the optical laminate of the present invention is mounted on the display surface, the dark room contrast is inferior and the visibility may be impaired. In the present specification, the contrast ratio is a value measured by the following method.
That is, using a cold cathode tube light source with a diffusion plate as a backlight unit, using two polarizing plates (AMN-3244TP manufactured by Samsung Co.), the light passing through when the polarizing plate is installed in parallel Nicol the _{L max} luminance values divided by the brightness of _{L min} of light passing through when installed in a cross nicol state with _(L max _{/ L min)} and contrast, optical laminate (light-transmitting substrate + hard coat layer, etc. the contrast _{(L 1)} of the) divided by the contrast _{(L 2)} of the light-transmitting substrate _{(L 1 / L 2) ×} 100 (%) is the contrast ratio.
Note that the luminance is measured in a dark room. The luminance is measured with a color luminance meter (BM-5A manufactured by Topcon Corporation), the measurement angle of the color luminance meter is set to 1 °, and the measurement is performed with a visual field of 5 mm on the sample. The light quantity of the backlight is set so that the luminance is 3600 cd / m ² when the two polarizing plates are set in parallel Nicol without the sample.

When the optical functional layer is a hard coat layer, the optical layered body of the present invention comprises a hard coat layer composition containing, for example, silica fine particles, a binder resin monomer component, and a solvent on a light-transmitting substrate. It can be manufactured by forming a hard coat layer. In the case where the optical functional layer has a structure in which a low refractive index layer is laminated on the hard coat layer, a hard coat containing, for example, silica fine particles, a monomer component of a binder resin, and a solvent on a light-transmitting substrate. After forming a hard-coat layer using the layer composition, it can manufacture by forming a low-refractive-index layer on a hard-coat layer using the composition for low-refractive-index layers mentioned above.
About the formation method of the said composition for hard-coat layers and a hard-coat layer, the composition for low-refractive-index layers, and the formation method of a low-refractive-index layer, the material and method similar to having mentioned above are mentioned.

The optical layered body of the present invention can be made into a polarizing plate by providing the optical layered body according to the present invention on the surface of the polarizing element opposite to the surface where the hard coat layer is present in the optical layered body. Such a polarizing plate is also one aspect of the present invention.

The polarizing element is not particularly limited, and for example, a polyvinyl alcohol film, a polyvinyl formal film, a polyvinyl acetal film, an ethylene-vinyl acetate copolymer saponified film, etc. dyed and stretched with iodine or the like can be used. In the laminating process of the polarizing element and the optical laminate of the present invention, it is preferable to saponify the light-transmitting substrate (triacetyl cellulose film). By the saponification treatment, the adhesiveness is improved and an antistatic effect can be obtained.

This invention is also an image display apparatus provided with the said optical laminated body or the said polarizing plate.
The image display device may be an image display device such as LCD, PDP, FED, ELD (organic EL, inorganic EL), CRT, tablet PC, touch panel, and electronic paper.

The LCD, which is a typical example of the above, includes a transmissive display body and a light source device that irradiates the transmissive display body from the back. When the image display device of the present invention is an LCD, the optical laminate of the present invention or the polarizing plate of the present invention is formed on the surface of this transmissive display.

In the case where the present invention is a liquid crystal display device having the optical laminate, the light source of the light source device is irradiated from the lower side of the optical laminate. Note that a retardation plate may be inserted between the liquid crystal display element and the polarizing plate. An adhesive layer may be provided between the layers of the liquid crystal display device as necessary.

The PDP, which is the image display device, has a front glass substrate (electrode is formed on the surface) and a rear glass substrate (disposed with electrodes and minute grooves) disposed with a discharge gas sealed between the front glass substrate and the front glass substrate. Formed on the surface and forming red, green and blue phosphor layers in the grooves). When the image display device of the present invention is a PDP, the above-mentioned optical laminate is provided on the surface of the surface glass substrate or the front plate (glass substrate or film substrate).

The above image display device is a zinc sulfide or diamine substance that emits light when a voltage is applied: a light emitting material is deposited on a glass substrate, and an ELD device that performs display by controlling the voltage applied to the substrate, or converts an electrical signal into light Alternatively, it may be an image display device such as a CRT that generates an image visible to human eyes. In this case, the optical laminated body described above is provided on the outermost surface of each display device as described above or the surface of the front plate.

In any case, the image display device of the present invention can be used for display display of a television, a computer, electronic paper, a touch panel, a tablet PC, or the like. In particular, it can be suitably used for the surface of high-definition image displays such as CRT, liquid crystal panel, PDP, ELD, FED, and touch panel.

Since the optical layered body of the present invention has the above-described configuration, it is possible to reduce the thickness of the optical functional layer without causing the occurrence of cloudiness while sufficiently suppressing the occurrence of interference fringes and curls. An increase in manufacturing cost can be prevented.
Therefore, the optical laminate of the present invention is suitable for cathode ray tube display (CRT), liquid crystal display (LCD), plasma display (PDP), electroluminescence display (ELD), field emission display (FED), electronic paper, etc. Can be applied to.

It is explanatory drawing of the measuring method of (theta) a. 6 is a cross-sectional photograph of an optical layered body according to Example 5. 2 is a cross-sectional photograph of an optical laminate according to Comparative Example 1.

The contents of the present invention will be described with reference to the following examples, but the contents of the present invention should not be construed as being limited to these embodiments. Unless otherwise specified, “part” and “%” are based on mass.

Example 1
A light-transmitting base material (thickness 60 μm triacetyl cellulose resin film, manufactured by Fuji Film Co., Ltd., TD60UL) was prepared, and a hard coat layer composition having the following composition was applied to one side of the light-transmitting base material. A coating film was formed. Next, 70 ° C. dry air was passed through the formed coating film at a flow rate of 0.2 m / s for 15 seconds, and then 70 ° C. dry air was passed through for 30 seconds at a flow rate of 10 m / s. By evaporating the solvent in the coating film, the integrated light quantity is 100 mJ / cm in a nitrogen atmosphere (oxygen concentration of 200 ppm or less) using an ultraviolet irradiation device (light source H bulb manufactured by Fusion UV System Japan Co., Ltd.). The hard coating layer having a thickness of 4 μm (at the time of curing) was formed by irradiating the coating so as to be ² to produce the optical laminate according to Example 1.

(Composition for hard coat layer)
Fumed silica (octylsilane treatment; average particle size 12 nm, manufactured by Nippon Aerosil Co., Ltd.)
1 part by mass pentaerythritol tetraacrylate (PETTA) (product name: PETA, manufactured by Daicel Cytec) 60 parts by mass urethane acrylate (product name: UV1700B, manufactured by Nippon Gosei Kagaku) 40 parts by mass Irgacure 184 (manufactured by BASF Japan) 5 parts by mass polyether-modified silicone (TSF4460, manufactured by Momentive Performance Materials) 0.025 parts by mass Toluene 105 parts by mass Isopropyl alcohol 30 parts by mass Cyclohexanone 15 parts by mass Fumed silica is a silane compound having an octyl group The silanol group is substituted with an octylsilyl group and is hydrophobized with (octylsilane).

(Example 2)
A composition for a hard coat layer was prepared in the same manner as in Example 1 except that the amount of fumed silica was changed to 1.5 parts by mass. Example 1 was conducted except that the composition for hard coat layer was used. In the same manner, an optical laminate according to Example 2 was manufactured.

(Example 3)
A composition for a hard coat layer was prepared in the same manner as in Example 1 except that the amount of fumed silica was changed to 0.5 parts by mass. Example 1 except that the composition for hard coat layer was used. In the same manner, an optical laminate according to Example 3 was manufactured.

Example 4
A composition for hard coat layer was prepared in the same manner as in Example 1 except that the amount of fumed silica was changed to 2.5 parts by mass, and Example 1 was prepared except that the composition for hard coat layer was used. In the same manner, an optical laminate according to Example 4 was manufactured.

(Example 5)
A light-transmitting base material (thickness 60 μm triacetyl cellulose resin film, manufactured by Fuji Film Co., Ltd., TD60UL) was prepared, and a hard coat layer composition having the following composition was applied to one side of the light-transmitting base material. A coating film was formed. Next, 70 ° C. dry air was passed through the formed coating film at a flow rate of 0.2 m / s for 15 seconds, and then 70 ° C. dry air was passed through for 30 seconds at a flow rate of 10 m / s. By evaporating the solvent in the coating film, the accumulated light amount is 50 mJ / cm in a nitrogen atmosphere (oxygen concentration of 200 ppm or less) using an ultraviolet irradiation device (Fusion UV System Japan, light source H bulb). ^By irradiating the coating film so as to be ² , a hard coat layer having a thickness of 4 μm (during curing) was formed.

(Composition for hard coat layer)
Fumed silica (octylsilane treatment; average particle size 12 nm, manufactured by Nippon Aerosil Co., Ltd.)
1 part by mass pentaerythritol tetraacrylate (PETTA) (product name: PETA, manufactured by Daicel Cytec) 60 parts by mass urethane acrylate (product name: UV1700B, manufactured by Nippon Gosei Kagaku) 40 parts by mass Irgacure 184 (manufactured by BASF Japan) 5 parts by mass polyether-modified silicone (TSF4460, manufactured by Momentive Performance Materials) 0.025 parts by mass Toluene 105 parts by mass Isopropyl alcohol 30 parts by mass Cyclohexanone 15 parts by mass Fumed silica is a silane compound having an octyl group The silanol group is substituted with an octylsilyl group and is hydrophobized with (octylsilane).

Next, a low refractive index layer composition having the following composition was applied to the surface of the formed hard coat layer so that the film thickness after drying (40 ° C. × 1 minute) was 0.1 μm, and an ultraviolet irradiation device ( Using a fusion UV system Japan, light source H bulb), under a nitrogen atmosphere (oxygen concentration of 200 ppm or less), UV irradiation is performed with an integrated light amount of 100 mJ / cm ² to cure, and a low refractive index layer is formed. The optical laminated body which concerns on Example 5 was manufactured.

(Composition for low refractive index layer)
Hollow silica fine particles (solid content of the silica fine particles: 20% by mass, solution; methyl isobutyl ketone, average particle size: 50 nm) 40 parts by mass pentaerythritol triacrylate (PETA) (manufactured by Daicel Cytec)
10 parts by mass polymerization initiator (Irgacure 127; manufactured by BASF Japan) 0.35 parts by mass modified silicone oil (X22164E; manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5 parts by mass MIBK 320 parts by mass PGMEA 161 parts by mass

(Example 6)
A composition for hard coat layer was prepared in the same manner as in Example 5 except that the amount of fumed silica was changed to 1.5 parts by mass, and Example 5 was prepared except that the composition for hard coat layer was used. In the same manner, an optical laminate according to Example 6 was manufactured.

(Example 7)
A composition for a hard coat layer was prepared in the same manner as in Example 5 except that the amount of fumed silica was changed to 0.5 parts by mass, and Example 5 was prepared except that the composition for hard coat layer was used. In the same manner, an optical laminate according to Example 7 was manufactured.

(Example 8)
A composition for hard coat layer was prepared in the same manner as in Example 5 except that the amount of fumed silica was changed to 2.5 parts by mass, and Example 5 was used except that the composition for hard coat layer was used. In the same manner, an optical laminate according to Example 8 was manufactured.

Example 9
A composition for a hard coat layer was prepared in the same manner as in Example 1 except that the amount of fumed silica was changed to 4 parts by mass, and the same as in Example 1 except that the composition for hard coat layer was used. Thus, an optical laminate according to Example 9 was produced.

(Comparative Example 1)
Instead of fumed silica, 1.5 parts by mass of gel method silica fine particles (average particle size 1.5 μm, manufactured by AX-204 Nippon Tosoh Silica Co., Ltd.) was used, except that the coating thickness at the time of curing was 1.5 μm. Prepared an optical laminate according to Comparative Example 1 in the same manner as in Example 1 except that a hard coat layer composition was prepared in the same manner as in Example 1, and the hard coat layer composition was used. .

(Comparative Example 2)
An optical laminate according to Comparative Example 2 was produced in the same manner as in Example 1 except that the hard coat layer composition having the composition shown below was used and the hard coat layer to be formed was 10 μm thick (at the time of curing). .

(Composition for hard coat layer)
Pentaerythritol triacrylate (PETA) (product name: PET30, manufactured by Nippon Kayaku Co., Ltd.) 100 parts by mass Irgacure 184 (manufactured by BASF Japan) 5 parts by mass polyether-modified silicone (TSF4460, manufactured by Momentive Performance Materials) 0 0.025 parts by mass Methyl ethyl ketone (MEK) 80 parts by mass Methyl isobutyl ketone (MIBK) 35 parts by mass

The optical laminates according to the obtained examples and comparative examples were evaluated for the following items.
All the results are shown in Table 1.

(Average inclination angle (θa) of uneven portion, skewness of uneven portion (Sk), arithmetic average roughness of uneven portion (Ra)
Using a surface roughness measuring instrument: SE-3400 / manufactured by Kosaka Laboratory Co., Ltd., in accordance with JIS B 0601-1994, and measuring the roughness curve under the following conditions, θa, Sk and Ra are It was measured. In Table 1, skewness (Sk) indicates an actual measurement value.
(1) The stylus of the surface roughness detector:
Model No./SE2555N (2μ stylus), manufactured by Kosaka Laboratory Ltd. (tip radius of curvature 2μm / vertical angle: 90 degrees / material: diamond)
(2) Measurement conditions of surface roughness measuring instrument:
Reference length (cutoff value λc of roughness curve): 2.5 mm
Evaluation length (reference length (cutoff value λc) × 5): 12.5 mm
Feeding speed of stylus: 0.5 mm / s
Preliminary length: (cutoff value λc) × 2
Longitudinal magnification: 2000 times Lateral magnification: 10 times Usually, a cutoff value of 0.8 mm is often used, but in the present invention, the measurement was performed with the cutoff value set to 2.5 mm.
In addition, λa was calculated by an equation of λa = 2π × (Ra / tan (θa)).

(Haze)
Based on JIS K7136, the haze of the obtained optical laminated body was measured using haze meter HM-150 (made by Murakami Color Research Laboratory).

(Transparent image definition)
In accordance with JIS K7105, transmission image definition was measured at 0.125 mm comb and 2.0 mm comb of the obtained optical laminate by transmission measurement using a image clarity measuring device ICM-1T (manufactured by Suga Test Instruments). .

(Interference fringes)
The surface (light transmissive substrate surface) opposite to the hard coat layer of each optical laminate obtained in Examples and Comparative Examples is pasted on a black acrylic plate for preventing back reflection through a transparent adhesive. Each optical layered product was irradiated with a sodium lamp from the surface of the hard coat layer or the low refractive index layer and visually observed, and the presence or absence of interference fringes was evaluated according to the following criteria.
A: No interference fringes were generated.
○: Some interference fringes were generated, but there was no problem.
X: Interference fringes were generated.
(Cloudiness)
The surface (light transmissive substrate surface) opposite to the hard coat layer of each optical laminate obtained in Examples and Comparative Examples was attached to a black acrylic plate via a transparent adhesive, and a table stand ( The cloudiness was observed under a three-wavelength fluorescent lamp tube) and evaluated according to the following criteria.
A: Whiteness was not observed.
○: Slight whiteness was observed but not so much.
X: Whiteness was observed.

(curl)
The curl degree of the optical laminate is measured by measuring the distance between the end points of the hard coat layer by placing a sample piece obtained by cutting the optical laminate according to the example and the comparative example into 10 cm × 10 cm on a horizontal base (plane). The average value (mm) of the distance was expressed as follows.
○: 80 mm or more ×: less than 80 mm

As shown in Table 1, the optical laminates according to the examples were good in all the evaluations of interference fringes, cloudiness, and curls. In addition, the optical laminates according to the examples have good results because the evaluation of the transmitted image definition is 75 to 95% in the 0.125 mm comb and 95% or more in the 2.0 mm comb. The haze was also sufficiently low.
On the other hand, in the optical laminate according to Comparative Example 1, silica is not distributed in a capillary shape, and a smooth uneven shape cannot be formed. Therefore, the value of θa is large, and the cloudiness and transmitted image definition are inferior. Met. Moreover, the optical laminate according to Comparative Example 2 uses MEK that swells the light-transmitting substrate as the hard coat layer composition, and further increases the coating amount so that the hard coat layer thickness becomes 10 μm. Interference fringes are prevented by reducing the reflected light from the interface between the hard coat layer and the light-transmitting substrate, but the curl evaluation is inferior.

Moreover, the maximum area ratio in the cross section of the thickness direction of the hard-coat layer of the optical laminated body which concerns on each Example and Comparative Example 1 was computed with the following method.
After embedding each obtained optical laminate with an embedding resin, it is cut in a direction perpendicular to the surface of the optical laminate with a microtome to produce a 70 nm-thick section, and the hard coat layer section that appears is scanned. Using a scanning electron microscope (STEM: S-4800, manufactured by Hitachi High-Tech), measurement was performed at a magnification of 10,000 times, and a cross-sectional photograph of each optical laminate was taken. The photographed image was taken into image processing software (Image-Pro Plus ver. 6.2 manufactured by Media Cybernetics). A 2 μm square area is selected and limited using a rectangular ROI with Image-Pro Plus, and the count / size command is used (the brightness range selection condition is “automatically extract dark colored objects”), and the black part (represents silica particles) ) And the area ratio was calculated by dividing the total area of the 2 μm square area (= 4 μm ² ). The area ratio was calculated by visually selecting 10 places where a large amount of silica fine particles were present in the photographed image, and the maximum value was set as the maximum area ratio.
The aspect ratio was calculated as follows.
A cross-sectional image in the thickness direction of the hard coat layer of the optical laminate taken in the same manner as described above is imported into image processing software (Image-Pro Plus), a morphological tab is selected from the Image-Pro Plus filter command, and “ Filtering was applied under the conditions of “shrinkage” and optionally “7 × 7 circle, number of times: 1”. Next, the silica aggregate was measured using a count / size command (the luminance range selection condition was “automatically extract dark color object”), and the elliptical / minor axis ratio of the measurement item was calculated. At that time, the selection range was as shown below. Of the measured ellipse major axis ratio, the average of the five largest ones (all the extracted particles when the number of extracted particles is less than 5) was taken as the aspect ratio.
<Selection range> Ellipse long / short axis ratio (1 to 1000000), area (1000 to 98419000 nm ² ), ferret diameter (minimum) (0 to 9920645 nm), ferret diameter (maximum) (500 to 9920645 nm)

A cross-sectional photograph of the optical laminated body according to Example 5 is shown in FIG. 2, and a cross-sectional photograph of the optical laminated body according to Comparative Example 1 is shown in FIG.
As shown in FIG. 2, in the optical laminate according to Example 5, the silica fine particles in the hard coat layer were distributed in the shape of capillaries, the maximum area ratio was 19%, and the aspect ratio was 3.5. . Although not shown for optical laminates according to other examples, the silica fine particles in the hard coat layer are distributed in a capillary shape, the maximum area ratio is 30% or less, and the aspect ratio is 2.0 or more. Met.
Also, as shown in FIG. 3, in the optical laminate according to Comparative Example 1, the silica fine particles in the hard coat layer are distributed as a dense lump, the maximum area ratio is 40%, and the aspect ratio is 1.6. there were.

The optical laminate of the present invention includes a cathode ray tube display (CRT), a liquid crystal display (LCD), a plasma display (PDP), an electroluminescence display (ELD), a field emission display (FED), a touch panel, electronic paper, a tablet PC, and the like. It can be suitably applied to.

Claims (8)

An optical laminate having an optical functional layer having a concavo-convex shape on the surface on one surface of the light-transmitting substrate,
The optical functional layer contains silica fine particles,
The silica fine particles are distributed in a three-dimensional network in the optical functional layer,
In the cross section in the thickness direction of the optical functional layer, a region including a portion where the silica fine particles are distributed in a three-dimensional network is observed under an electron microscope at a magnification of 10,000 times, and 2 μm from the observation screen. area ratio of the silica fine particles when the area ratio of the silica fine particles in the square region chose the 2μm square region as best becomes large state, and are 30% or less,
The optical laminated body, wherein the uneven shape on the surface of the optical functional layer has an average inclination angle? A of the uneven portion satisfying the following formula .
0.01 ° ≦ θa ≦ 0.09 ° 2. The optical laminate according to claim 1, wherein the uneven shape on the surface of the optical functional layer has an absolute value of Sk satisfying the following formula, where Sk is the skewness of the unevenness .
| Sk | ≦ 0.5 3. The optical laminate according to claim 1, wherein the concavo-convex shape of the optical functional layer satisfies the following formula when the arithmetic average roughness of the concavo-convex is Ra.
0.02 μm ≦ Ra ≦ 0.10 μm 4. The optical laminate according to claim 3, wherein the uneven shape of the optical functional layer has an average wavelength λa represented by λa = 2π × (Ra / tan (θa)) satisfying the following formula.
200 μm ≦ λa ≦ 800 μm The optical layered body according to claim 1, 2, 3, or 4, wherein the optical functional layer is a hard coat layer. The optical laminated body according to claim 1, 2, 3, or 4, wherein the optical functional layer has a structure in which a low refractive index layer is laminated on a hard coat layer. A polarizing plate comprising a polarizing element,
The said polarizing plate is equipped with the optical laminated body of Claim 1, 2, 3, 4, 5 or 6 on the polarizing element surface, The polarizing plate characterized by the above-mentioned. An image display device comprising the optical layered body according to claim 1, or the polarizing plate according to claim 7.