JP6235288B2 - Optical laminate - Google Patents

Description

  The present invention relates to an optical laminate.

  Image display devices such as liquid crystal display (LCD), cathode ray tube display device (CRT), plasma display (PDP), electroluminescence display (ELD), etc. are visible when the surface is damaged by external contact. May decrease. For this reason, the optical laminated body containing a base material layer and a hard-coat layer is used for the purpose of the surface protection of an image display apparatus.

  In addition, the image display device is required to reduce surface reflection due to light emitted from the outside and improve its visibility. In response to this requirement, use of an optical laminate having a configuration of [base layer / hard coat layer / antireflection layer] has been proposed. In the optical laminate having such a configuration, a high refractive index is required for the hard coat layer and a low refractive index is required for the antireflection layer from the viewpoint of reflectivity. Therefore, high refractive index fine particles and low refractive index fine particles are added to the hard coat layer and the antireflection layer, respectively. As a specific example, there is an optical laminate (antireflection film) including a high refractive index gradient hard coat layer in which the amount of high refractive index fine particles is continuously changed in the film thickness direction (for example, Patent Document 1). . According to the antireflection film, interference unevenness can be prevented. However, sufficient hardness may not be obtained.

JP 2011-145649 A

  The present invention provides an optical laminate that includes a base material layer and a hard coat layer, prevents interference unevenness, and has sufficient hardness.

The optical laminate of the present invention is a hard coat comprising a base material layer formed from a thermoplastic resin film, a curable compound having a molecular weight of 600 to 2500, and fine particles having a high refractive index of 1.50 or more. A hard coat layer formed by applying the layer forming composition to the thermoplastic resin film, and the hard coat layer penetrates the thermoplastic resin film. Including the formed penetrating region, the high refractive index fine particles segregate in the hard coat layer so that the concentration continuously decreases in the thickness direction from the surface on which the base material layer is not provided. doing.
In one embodiment, the said curable compound contains the oligomer of urethane (meth) acrylate and / or urethane (meth) acrylate.
In one embodiment, no phase separation occurs in the hard coat layer.
In one embodiment, the thermoplastic resin film is a (meth) acrylic resin film.
In one embodiment, the hard coat layer includes a thermoplastic resin that forms the thermoplastic resin film so that the concentration continuously decreases from the surface of the base material layer toward the thickness direction.
In one embodiment, a low refractive index layer is further provided on the side of the hard coat layer where the base material layer is not provided.
According to another aspect of the present invention, a polarizing film is provided. This polarizing film contains the said optical laminated body.
According to still another aspect of the present invention, an image display device is provided. The image display device includes the optical laminate.

  In the present invention, a composition for forming a hard coat layer containing a curable compound having a predetermined molecular weight and high refractive index fine particles is applied onto a thermoplastic resin film, and a part of the composition is allowed to penetrate into the thermoplastic resin film. To form an infiltration region. As a result, the hard coat layer can be made to have a high refractive index with a small amount of high refractive index fine particles, interference unevenness can be prevented, and sufficient hardness can be obtained. Furthermore, the optical layered body of the present invention can be manufactured by a simple manufacturing method.

It is a schematic sectional drawing of the optical laminated body by one Embodiment of this invention. It is a schematic sectional drawing of the optical laminated body by another embodiment of this invention. (A) is the TEM photograph of the hard-coat layer cross section of the optical laminated body of Example 1, (b) is the partial enlarged photograph. It is a graph showing the reflection spectrum of the optical laminated body obtained by the Example and the comparative example. (A) is a TEM photograph showing a cross section of the optical laminate T1, and (b) is a TEM photograph showing a cross section of the optical laminate T2.

Hereinafter, although preferable embodiment of this invention is described, this invention is not limited to these embodiment.
A. FIG. 1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. The optical laminate 100 shown in FIG. 1 includes a base material layer 10 formed from a thermoplastic resin film and a hard coat layer 20 in this order. The hard coat layer 20 is formed by applying a composition for forming a hard coat layer to a thermoplastic resin film. The hard coat layer 20 includes a penetrating region 22 formed by penetrating a part of the applied hard coat layer forming composition into the thermoplastic resin film. In other words, the permeation region 22 is a portion where a hard coat layer forming composition component is present in the thermoplastic resin film. On the other hand, the base material layer 10 is a portion where the hard coat layer forming composition did not reach (penetrate) in the thermoplastic resin film when the hard coat layer forming composition penetrated into the thermoplastic resin film. It is. In addition, the boundary A in a figure is a boundary prescribed | regulated by the composition application | coating surface for hard-coat layer formation of a thermoplastic resin film.

  FIG. 2 is a schematic cross-sectional view of an optical laminate according to another embodiment of the present invention. The optical laminate 200 further includes a low refractive index layer 30 on the side of the hard coat layer 20 where the base material layer 10 is not provided.

  The optical layered body of the present invention is applied to, for example, a polarizing film (also referred to as a polarizing plate). Specifically, the optical laminate of the present invention is provided on one or both sides of a polarizer in a polarizing film, and can be suitably used as a protective material for the polarizer.

B. Base material layer The base material layer is formed from any appropriate thermoplastic resin film. More specifically, when the hard coat layer forming composition was applied to the thermoplastic resin film, the hard coat layer forming composition did not reach (penetrate) in the thermoplastic resin film. Part.

  Specific examples of the thermoplastic resin film include (meth) acrylic resin film, cellulose resin film such as triacetyl cellulose, polyolefin resin film such as polyethylene and polypropylene; cycloolefin resin film such as polynorbornene, polyethylene terephthalate And polyester-based resin films such as polybutylene terephthalate. Of these, a (meth) acrylic resin film is preferable. When a (meth) acrylic resin film is used as the base film, the permeation region can be formed well. In the present specification, “(meth) acryl” means acryl and / or methacryl.

  The transmittance of light at a wavelength of 380 nm of the thermoplastic resin film is preferably 15% or less, more preferably 12% or less, and further preferably 9% or less. If the transmittance of light having a wavelength of 380 nm is in such a range, an excellent ultraviolet absorbing ability is exhibited, so that deterioration of ultraviolet rays due to external light or the like of the optical laminate can be prevented.

The in-plane retardation Re of the thermoplastic resin film is preferably 10 nm or less, more preferably 7 nm or less, further preferably 5 nm or less, particularly preferably 3 nm or less, and most preferably 1 nm or less. is there. The thickness direction retardation Rth of the thermoplastic resin film is preferably 15 nm or less, more preferably 10 nm or less, further preferably 5 nm or less, particularly preferably 3 nm or less, and most preferably 1 nm or less. . If the in-plane retardation and the thickness direction retardation are within such ranges, the adverse effect on the display characteristics of the image display apparatus due to the phase difference can be remarkably suppressed. More specifically, interference unevenness and 3D image distortion when used in a liquid crystal display device for 3D display can be significantly suppressed. The in-plane retardation Re and the thickness direction retardation Rth can be obtained by the following equations, respectively:
Re = (nx−ny) × d
Rth = (nx−nz) × d
Here, nx is the refractive index in the slow axis direction of the thermoplastic resin film, ny is the refractive index in the fast axis direction of the thermoplastic resin film, and nz is the refractive index in the thickness direction of the thermoplastic resin film. Yes, d (nm) is the thickness of the thermoplastic resin film. The slow axis refers to the direction in which the in-plane refractive index is maximized, and the fast axis refers to the direction perpendicular to the slow axis in the plane. Typically, Re and Rth are measured using light having a wavelength of 590 nm.

  The (meth) acrylic resin film includes a (meth) acrylic resin. The (meth) acrylic resin film is obtained, for example, by extruding a molding material containing a resin component containing a (meth) acrylic resin as a main component. As a specific example, a (meth) acrylic resin film having an in-plane retardation and a thickness direction retardation within the above ranges can be obtained using, for example, a (meth) acrylic resin having a glutarimide structure described later. .

The moisture permeability of the (meth) acrylic resin film is preferably 200 g / m ² · 24 hr or less, and more preferably 80 g / m ² · 24 hr or less. According to the present invention, even when a (meth) acrylic resin film having such a high moisture permeability is used, the adhesion between the (meth) acrylic resin film and the hard coat layer is excellent, and interference unevenness is suppressed. An optical laminate can be obtained. The moisture permeability can be measured under the test conditions of 40 ° C. and a relative humidity of 92%, for example, by a method according to JIS Z 0208.

Any appropriate (meth) acrylic resin can be adopted as the (meth) acrylic resin. For example, poly (meth) acrylic acid ester such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester -(Meth) acrylic acid copolymer, (meth) acrylic acid methyl-styrene copolymer (MS resin, etc.), polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer) And methyl methacrylate- (meth) acrylate norbornyl copolymer). Preferably, poly (meth) acrylic acid C _1-6 alkyl such as poly (meth) acrylate methyl is used. More preferably, a methyl methacrylate resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight) is used.

  The weight average molecular weight of the (meth) acrylic resin is preferably 10,000 to 500,000, more preferably 30,000 to 300,000, and still more preferably 50,000 to 200,000. If the weight average molecular weight is within this range, the permeability and compatibility with the hard coat layer forming composition are appropriate. On the other hand, if the weight average molecular weight is too small, the mechanical strength of the film tends to be insufficient. When the weight average molecular weight is too large, the viscosity at the time of melt extrusion is high, the molding processability is lowered, and the productivity of the molded product tends to be lowered.

  The glass transition temperature of the (meth) acrylic resin is preferably 110 ° C. or higher, more preferably 120 ° C. or higher. When the glass transition temperature is in such a range, a (meth) acrylic resin film excellent in durability and heat resistance can be obtained. The upper limit of the glass transition temperature is not particularly limited, but is preferably 170 ° C. or less from the viewpoint of moldability and the like.

  The (meth) acrylic resin preferably has a structural unit that exhibits positive birefringence and a structural unit that exhibits negative birefringence. If these structural units are included, the abundance ratio can be adjusted to control the retardation of the (meth) acrylic resin film, and a (meth) acrylic resin film having a low retardation can be obtained. it can. Examples of the structural unit that exhibits positive birefringence include a structural unit constituting a lactone ring, polycarbonate, polyvinyl alcohol, cellulose acetate, polyester, polyarylate, polyimide, polyolefin, and the like, represented by the general formula (1) described later. Examples include structural units. Examples of the structural unit exhibiting negative birefringence include a structural unit derived from a styrene monomer, a maleimide monomer, a structural unit of polymethyl methacrylate, a structural unit represented by the general formula (3) described later, and the like. Can be mentioned. In the present specification, a structural unit that exhibits positive birefringence is a case where a resin having only the structural unit exhibits positive birefringence characteristics (that is, a slow axis appears in the stretching direction of the resin). Means a structural unit. In addition, a structural unit that develops negative birefringence is when a resin having only the structural unit exhibits negative birefringence characteristics (that is, when a slow axis appears in a direction perpendicular to the stretching direction of the resin). Means a structural unit of

  As the (meth) acrylic resin, a (meth) acrylic resin having a lactone ring structure or a glutarimide structure is preferably used. A (meth) acrylic resin having a lactone ring structure or a glutarimide structure is excellent in heat resistance. More preferred is a (meth) acrylic resin having a glutarimide structure. If a (meth) acrylic resin having a glutarimide structure is used, a (meth) acrylic resin film having low moisture permeability and a small retardation and ultraviolet transmittance can be obtained as described above. Examples of (meth) acrylic resins having a glutarimide structure (hereinafter also referred to as glutarimide resins) include, for example, JP-A-2006-309033, JP-A-2006-317560, JP-A-2006-328329, and JP-A-2006-328329. 2006-328334, JP-A 2006-337491, JP-A 2006-337492, JP-A 2006-337493, JP-A 2006-337469, JP-A 2007-009182, JP-A 2009- No. 161744. These descriptions are incorporated herein by reference.

Preferably, the glutarimide resin includes a structural unit represented by the following general formula (1) (hereinafter also referred to as a glutarimide unit) and a structural unit represented by the following general formula (2) (hereinafter referred to as (meta)). Also referred to as an acrylate unit).
In Formula (1), R ¹ and R ² are each independently hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ³ is hydrogen, an alkyl group having 1 to 18 carbon atoms, or 3 to 3 carbon atoms. It is a substituent containing 12 cycloalkyl groups or an aromatic ring having 5 to 15 carbon atoms. In Formula (2), R ⁴ and R ⁵ are each independently hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ⁶ is hydrogen, an alkyl group having 1 to 18 carbon atoms, or 3 to 3 carbon atoms. It is a substituent containing 12 cycloalkyl groups or an aromatic ring having 5 to 15 carbon atoms.

The glutarimide resin may further contain a structural unit represented by the following general formula (3) (hereinafter also referred to as an aromatic vinyl unit) as necessary.
In Formula (3), R ⁷ is hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ⁸ is an aryl group having 6 to 10 carbon atoms.

In the general formula (1), preferably, R ¹ and R ² are each independently hydrogen or a methyl group, R ³ is hydrogen, a methyl group, a butyl group, or a cyclohexyl group, and more preferably , R ¹ is a methyl group, R ² is hydrogen, and R ³ is a methyl group.

The glutarimide resin may include only a single type as a glutarimide unit, or may include a plurality of types in which R ¹ , R ² , and R ³ in the general formula (1) are different. Good.

  The glutarimide unit can be formed by imidizing the (meth) acrylic acid ester unit represented by the general formula (2). The glutarimide unit is an acid anhydride such as maleic anhydride, or a half ester of such an acid anhydride and a linear or branched alcohol having 1 to 20 carbon atoms; acrylic acid, methacrylic acid, maleic acid. It can also be formed by imidizing an α, β-ethylenically unsaturated carboxylic acid such as maleic anhydride, itaconic acid, itaconic anhydride, crotonic acid, fumaric acid, citraconic acid and the like.

In the general formula (2), preferably, R ⁴ and R ⁵ are each independently hydrogen or a methyl group, R ⁶ is hydrogen or a methyl group, and more preferably, R ⁴ is hydrogen. , R ⁵ is a methyl group, and R ⁶ is a methyl group.

The glutarimide resin may contain only a single type as a (meth) acrylic acid ester unit, or a plurality of types in which R ⁴ , R ⁵ and R ⁶ in the general formula (2) are different. May be included.

  The glutarimide resin preferably contains styrene, α-methylstyrene, and more preferably styrene as the aromatic vinyl unit represented by the general formula (3). By having such an aromatic vinyl unit, the positive birefringence of the glutarimide structure can be reduced, and a (meth) acrylic resin film having a lower retardation can be obtained.

The glutarimide resin may contain only a single type as an aromatic vinyl unit, or may contain a plurality of types in which R ⁷ and R ⁸ are different.

The content of the glutarimide unit in the glutarimide resin is preferably changed depending on, for example, the structure of R ³ . The content of the glutarimide unit is preferably 1% by weight to 80% by weight, more preferably 1% by weight to 70% by weight, even more preferably 1% by weight, based on the total structural unit of the glutarimide resin. -60% by weight, particularly preferably 1-50% by weight. When the content of the glutarimide unit is in such a range, a (meth) acrylic resin film having a low retardation excellent in heat resistance can be obtained.

  The content of the aromatic vinyl unit in the glutarimide resin can be appropriately set according to the purpose and desired characteristics. Depending on the application, the content of the aromatic vinyl unit may be zero. When the aromatic vinyl unit is contained, the content thereof is preferably 10% by weight to 80% by weight, more preferably 20% by weight to 80% by weight, based on the glutarimide unit of the glutarimide resin. More preferably, it is 20 to 60% by weight, and particularly preferably 20 to 50% by weight. When the content of the aromatic vinyl unit is within such a range, a (meth) acrylic resin film having a low retardation, excellent heat resistance and mechanical strength can be obtained.

  The glutarimide resin may further be copolymerized with other structural units other than the glutarimide unit, the (meth) acrylic acid ester unit, and the aromatic vinyl unit, if necessary. Other structural units include, for example, nitrile monomers such as acrylonitrile and methacrylonitrile, and structures composed of maleimide monomers such as maleimide, N-methylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide. Units are listed. These other structural units may be directly copolymerized or graft copolymerized in the glutarimide resin.

  The thermoplastic resin film contains an ultraviolet absorber. As the ultraviolet absorber, any appropriate ultraviolet absorber can be adopted as long as the desired characteristics are obtained. Representative examples of the above UV absorbers include triazine UV absorbers, benzotriazole UV absorbers, benzophenone UV absorbers, cyanoacrylate UV absorbers, benzoxazine UV absorbers, and oxadiazole UV absorbers. Agents. These ultraviolet absorbers may be used alone or in combination.

  The content of the ultraviolet absorber is preferably 0.1 parts by weight to 5 parts by weight, and more preferably 0.2 parts by weight to 3 parts by weight with respect to 100 parts by weight of the thermoplastic resin. When the content of the ultraviolet absorber is in such a range, ultraviolet rays can be absorbed effectively and the transparency of the film during film formation does not deteriorate. When the content of the ultraviolet absorber is less than 0.1 parts by weight, the ultraviolet blocking effect tends to be insufficient. When there is more content of a ultraviolet absorber than 5 weight part, there exists a tendency for coloring to become intense or the haze of the film after shaping | molding becomes high, and transparency deteriorates.

  The thermoplastic resin film may contain any appropriate additive depending on the purpose. Examples of additives include hindered phenol-based, phosphorus-based and sulfur-based antioxidants; light-resistant stabilizers, weather-resistant stabilizers, heat stabilizers and other stabilizers; reinforcing materials such as glass fibers and carbon fibers; Infrared absorbers; flame retardants such as tris (dibromopropyl) phosphate, triallyl phosphate, antimony oxide; antistatic agents such as anionic, cationic and nonionic surfactants; coloring of inorganic pigments, organic pigments, dyes, etc. Agents; organic fillers and inorganic fillers; resin modifiers; plasticizers; lubricants; retardation reducing agents. The kind, combination, content, and the like of the additive to be contained can be appropriately set according to the purpose and desired characteristics.

  The method for producing the thermoplastic resin film is not particularly limited. For example, the thermoplastic resin, the ultraviolet absorber, and other polymers and additives as necessary may be arbitrarily selected. It is possible to form a film from a thermoplastic resin composition that has been sufficiently mixed by an appropriate mixing method. Alternatively, a thermoplastic resin, an ultraviolet absorber, and if necessary, other polymers and additives are mixed in separate solutions to form a uniform mixed solution, and then formed into a film. Good.

  In order to produce the thermoplastic resin composition, for example, the film raw material is pre-blended with any appropriate mixer such as an omni mixer, and then the obtained mixture is extrusion kneaded. In this case, the mixer used for extrusion kneading is not particularly limited, and for example, any suitable mixer such as an extruder such as a single screw extruder or a twin screw extruder or a pressure kneader may be used. Can do.

  Examples of the film forming method include any appropriate film forming method such as a solution casting method (solution casting method), a melt extrusion method, a calendar method, and a compression molding method. A melt extrusion method is preferred. Since the melt extrusion method does not use a solvent, it is possible to reduce the manufacturing cost and the burden on the global environment and work environment due to the solvent.

  Examples of the melt extrusion method include a T-die method and an inflation method. The molding temperature is preferably 150 to 350 ° C, more preferably 200 to 300 ° C.

  When film-forming by the above T-die method, a T-die is attached to the tip of a known single-screw extruder or twin-screw extruder, and the film extruded into a film is wound to obtain a roll-shaped film Can do. At this time, it is possible to perform uniaxial stretching by appropriately adjusting the temperature of the winding roll and adding stretching in the extrusion direction. Also, simultaneous biaxial stretching, sequential biaxial stretching, and the like can be performed by stretching the film in a direction perpendicular to the extrusion direction.

  The thermoplastic resin film may be either an unstretched film or a stretched film as long as the desired retardation is obtained. In the case of a stretched film, either a uniaxially stretched film or a biaxially stretched film may be used. In the case of a biaxially stretched film, either a simultaneous biaxially stretched film or a sequential biaxially stretched film may be used.

  The stretching temperature is preferably in the vicinity of the glass transition temperature of the thermoplastic resin composition that is the film raw material, and specifically, preferably (glass transition temperature-30 ° C.) to (glass transition temperature + 30 ° C.) Preferably, it is within the range of (glass transition temperature−20 ° C.) to (glass transition temperature + 20 ° C.). If the stretching temperature is lower than (glass transition temperature −30 ° C.), the haze of the resulting film may increase, or the film may be torn or cracked, resulting in failure to obtain a predetermined stretching ratio. On the other hand, when the stretching temperature exceeds (glass transition temperature + 30 ° C.), the thickness unevenness of the resulting film becomes large, and the mechanical properties such as elongation, tear propagation strength, and fatigue resistance cannot be sufficiently improved. There is a tendency to. Furthermore, there is a tendency that troubles such as the film sticking to the roll tend to occur.

  The draw ratio is preferably 1.1 to 3 times, more preferably 1.3 to 2.5 times. When the draw ratio is in such a range, the mechanical properties such as the film elongation, tear propagation strength, and fatigue resistance can be greatly improved. As a result, it is possible to produce a film with small thickness unevenness, substantially zero birefringence (and therefore a small phase difference), and a small haze.

  The thermoplastic resin film can be subjected to a heat treatment (annealing) or the like after the stretching treatment in order to stabilize its optical isotropy and mechanical properties. Arbitrary appropriate conditions can be employ | adopted for the conditions of heat processing.

  The thickness of the thermoplastic resin film is preferably 10 μm to 200 μm, more preferably 20 μm to 100 μm. There exists a possibility that intensity | strength may fall that thickness is less than 10 micrometers. If the thickness exceeds 200 μm, the transparency may decrease.

  The surface tension of the thermoplastic resin film is preferably 40 mN / m or more, more preferably 50 mN / m or more, and still more preferably 55 mN / m or more. When the surface wetting tension is 40 mN / m or more, the adhesion between the thermoplastic resin film and the hard coat layer is further improved. Any suitable surface treatment can be applied to adjust the surface wetting tension. Examples of the surface treatment include corona discharge treatment, plasma treatment, ozone spraying, ultraviolet irradiation, flame treatment, and chemical treatment. Of these, corona discharge treatment and plasma treatment are preferable.

B. Hard coat layer The hard coat layer is formed by applying a composition for forming a hard coat layer containing a curable compound having a predetermined molecular weight and high refractive index fine particles to a thermoplastic resin film. More specifically, the hard coat layer is formed by applying a hard coat layer forming composition containing a curable compound having a predetermined molecular weight and high refractive index fine particles to a thermoplastic resin film, and a part of the hard coat layer is formed on the thermoplastic resin film. It is formed by infiltrating into. Preferably, elution of the thermoplastic resin that forms the thermoplastic resin film into the coating layer of the hard coat layer forming composition occurs simultaneously with the penetration of the hard coat layer forming composition into the thermoplastic resin film.

  As described above, the hard coat layer includes an infiltrated region formed by infiltrating the thermoplastic resin film with the hard coat layer forming composition. In the infiltration region, typically, the thermoplastic resin forming the thermoplastic resin film and the hard coat layer forming composition are compatible.

  The lower limit of the penetration depth into the thermoplastic resin film (thickness of the penetration region) of the composition for forming a hard coat layer is, for example, 1.2 μm, preferably 1.5 μm, more preferably 2.5 μm. More preferably, it is 3 μm. The upper limit of the penetration depth is preferably (thermoplastic resin film thickness × 70%) μm, more preferably (thermoplastic resin film thickness × 40%) μm, and even more preferably (thermoplastic resin film). Thickness × 30%) μm, particularly preferably (thermoplastic resin film × 20%) μm. When the penetration depth is within such a range, an optical laminate having excellent adhesion between the thermoplastic resin film and the hard coat layer, suppressing interference unevenness, and excellent hardness can be obtained. The penetration depth can be measured by reflection with a hard coat layer or observation with an electron microscope such as SEM or TEM.

  The hard coat layer preferably contains a thermoplastic resin that forms a thermoplastic resin film in the permeation region so that its concentration continuously decreases from the base material layer side surface toward the opposite surface. The hard coat layer may also include a thermoplastic resin beyond the permeation region (ie, beyond the boundary line A in FIG. 1). Even in this case, it is preferable that the thermoplastic resin is contained so that its concentration continuously decreases from the base material layer side surface toward the opposite surface. This is because, by continuously changing the concentration of the thermoplastic resin, interface reflection between the base material layer and the hard coat layer can be suppressed, and an optical laminated body with less interference unevenness can be obtained. Further, segregation of high refractive index fine particles and formation of a concentration gradient described later can be suitably performed.

  The hard coat layer is preferably not phase-separated, in other words, has no upper and lower two-layer structure. When phase separation occurs in the hard coat layer and an upper and lower two-layer structure is formed, segregation of high refractive index fine particles and formation of a concentration gradient, which will be described later, may be insufficient. This is because when an upper and lower two-layer structure is formed, there is no thermoplastic resin concentration gradient in the upper layer (the base layer side layer is the lower layer) or the concentration gradient becomes gentle, resulting in high refraction. It is presumed that the fine particles can be dispersed with high uniformity. In the present invention, for example, in observation with an electron microscope such as SEM or TEM, it is confirmed that there is no phase separation interface in the hard coat layer, and the reflection spectrum of the hard coat layer is measured. It can be judged that there is no separation or upper and lower two-layer structure.

  In the hard coat layer, the high refractive index fine particles are segregated on the surface on the side where the base material layer is not provided, and the concentration continuously decreases from the surface in the thickness direction. By segregating high refractive index fine particles while forming a concentration gradient in this way, interference unevenness can be suitably suppressed with a small amount of high refractive index fine particles. Here, “the high refractive index fine particles are segregated on the surface on which the base material layer is not provided” means that 90% by weight or more of the high refractive index fine particles contained in the hard coat layer is the base material layer. It means that it exists in the area | region of the distance below the thickness direction (thickness of a hard-coat layer x80%) from the surface of the side in which no is provided. Preferably, 90% by weight or more of the high refractive index fine particles contained in the hard coat layer is present in a region at a distance from the surface in the thickness direction (hard coat layer thickness × 60%) or less.

  As the high refractive index fine particles, any appropriate fine particles having a refractive index of 1.50 or more are used. The upper limit of the refractive index can be, for example, 2.80. In the present specification, the refractive index means a refractive index at a wavelength of 590 nm.

Examples of the high refractive index fine particles include metal oxide fine particles. Specific examples of the metal oxide include titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), cerium oxide (CeO ₂ ), tin oxide (SnO ₂ ), antimony tin oxide (ATO), indium tin oxide ( ITO), phosphorus tin compound (PTO), antimony oxide (Sb ₂ O ₅ ), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), zinc antimonate (ZnSb ₂ O ₆ ), and the like.

  The average particle diameter of the high refractive index fine particles is preferably 1 nm to 100 nm, more preferably 1 nm to 50 nm. Such an average particle diameter is excellent in transparency and easy to handle. The average particle size is a value that is measured without distinguishing between primary particles and secondary particles, assuming that the secondary particles are also one particle. The average particle diameter can be obtained, for example, as an average value of the particle diameters of particles (for example, 50 particles) observed in a predetermined region of the cross section of the hard coat layer with a transmission electron microscope. .

  The content of the high refractive index fine particles in the hard coat layer forming composition is, for example, 10 to 80 parts by weight, preferably 15 to 50 parts by weight with respect to 100 parts by weight of the curable compound.

  The curable compound contained in the composition for forming a hard coat layer can be cured by heat, light (such as ultraviolet rays) or electron beam. The curable compound is preferably a photocurable curable compound. The curable compound may be any of a monomer, an oligomer and a prepolymer.

  In the present invention, the curable compound has a molecular weight of 2500 or less, preferably 2000 or less, more preferably 1800 or less, and still more preferably 1500 or less. When the molecular weight exceeds 2500, phase separation occurs in the hard coat layer, and as a result, interference unevenness may occur. The molecular weight of the curable compound is 600 or more, more preferably 800 or more, and still more preferably 1000 or more. When the molecular weight is less than 600, penetration of the composition for forming a hard coat layer into the thermoplastic resin film becomes excessive, and as a result, the desired hardness may not be achieved. In addition, when a curable compound is a mixture (for example, oligomer, prepolymer, etc.) of a some compound, the molecular weight of the said curable compound is a weight average molecular weight. In the case of using two or more kinds of curable compounds, “the molecular weight of the curable compounds is 2500 or less” means that the weighted average value of the molecular weights of the two or more curable compounds is 2500 or less. To do.

  As the curable compound, a curable compound having two or more (meth) acryloyl groups is preferably used. The upper limit of the number of (meth) acryloyl groups contained in the curable compound having two or more (meth) acryloyl groups is preferably 30. Since the curable compound having two or more (meth) acryloyl groups is excellent in compatibility with the (meth) acrylic resin, when a (meth) acrylic resin film is used as the thermoplastic resin film, It easily penetrates and diffuses into the (meth) acrylic resin film. In the present specification, “(meth) acryloyl” means methacryloyl and / or acryloyl.

  Specific examples of the curable compound having two or more (meth) acryloyl groups include tricyclodecane dimethanol diacrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, and trimethylolpropane triacrylate. , Pentaerythritol tetra (meth) acrylate, dimethylolpropanthate tetraacrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol (meth) acrylate, 1,9-nonanediol diacrylate, 1,10-decane Diol (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, dipropylene glycol diacrylate, isocyanuric acid tri Examples include (meth) acrylate, ethoxylated glycerin triacrylate, ethoxylated pentaerythritol tetraacrylate, and oligomers or prepolymers thereof. The curable compound having two or more (meth) acryloyl groups may be used alone or in combination. In the present specification, “(meth) acrylate” means acrylate and / or methacrylate.

  The curable compound having two or more (meth) acryloyl groups preferably has a hydroxyl group. If the composition for forming a hard coat layer contains such a curable compound, the heating temperature at the time of forming the hard coat layer can be set lower, the heating time can be set shorter, and deformation due to heating can be suppressed. The produced optical laminate can be produced efficiently. Moreover, the optical laminated body excellent in the adhesiveness of a thermoplastic resin film (for example, (meth) acrylic-type resin film) and a hard-coat layer can be obtained. Examples of the curable compound having a hydroxyl group and two or more (meth) acryloyl groups include pentaerythritol tri (meth) acrylate and dipentaerythritol pentaacrylate.

  In the present invention, urethane (meth) acrylate and / or urethane (meth) acrylate oligomers are preferably used as the curable compound having two or more (meth) acryloyl groups. The number of (meth) acryloyl groups contained in the urethane (meth) acrylate and / or urethane (meth) acrylate oligomer is preferably 3 or more, more preferably 4 to 15, and still more preferably 6 to 12.

  The molecular weight of the urethane (meth) acrylate and / or urethane (meth) acrylate is, for example, 3000 or less, preferably 500 to 2500, and more preferably 800 to 2000. Urethane (meth) acrylate and / or urethane (meth) acrylate oligomers having a molecular weight in the above range and having two or more (meth) acryloyl groups are thermoplastic resin films (especially (meth) acrylic). Resin film) and compatibility with thermoplastic resins (especially (meth) acrylic resins) are appropriate. As a result, a hard coat layer that does not have phase separation while maintaining hardness can be obtained.

  The urethane (meth) acrylate can be obtained, for example, by reacting hydroxy (meth) acrylate obtained from (meth) acrylic acid or (meth) acrylic acid ester and polyol with diisocyanate. Moreover, you may use arbitrary appropriate commercial items. Urethane (meth) acrylates and urethane (meth) acrylate oligomers may be used alone or in combination.

  Examples of the (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, and the like.

  Examples of the polyol include ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, diethylene glycol, dipropylene glycol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1, 6-hexanediol, 1,9-nonanediol, 1,10-decanediol, 2,2,4-trimethyl-1,3-pentanediol, 3-methyl-1,5-pentanediol, neopentyl hydroxypivalate Glycol ester, tricyclodecane dimethylol, 1,4-cyclohexanediol, spiroglycol, hydrogenated bisphenol A, ethylene oxide-added bisphenol A, propylene oxide-added bisphenol A, trimethylol ethane, trimethylol Propane, glycerin, 3-methylpentane-1,3,5-triol, pentaerythritol, dipentaerythritol, tripentaerythritol, glucose, etc. can be mentioned.

  As said diisocyanate, various aromatic, aliphatic, or alicyclic diisocyanates can be used, for example. Specific examples of the diisocyanate include tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 2,4-tolylene diisocyanate, 4,4-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 3,3-dimethyl-4,4. -Diphenyl diisocyanate, xylene diisocyanate, trimethylhexamethylene diisocyanate, 4,4-diphenylmethane diisocyanate, and hydrogenated products thereof.

  The content ratio of the curable compound having two or more (meth) acryloyl groups is preferably based on the total curable compound (total amount of monomer, oligomer and prepolymer) in the hard coat layer forming composition. It is 60 to 100% by weight, more preferably 70 to 100% by weight, and still more preferably 80 to 100% by weight. If it is such a range, the optical laminated body which was excellent in the adhesiveness of a thermoplastic resin film (for example, (meth) acrylic-type resin film) and a hard-coat layer, and the interference nonuniformity was suppressed can be obtained. . In addition, curing shrinkage of the hard coat layer can be effectively prevented.

  The total content of the urethane (meth) acrylate and the urethane (meth) acrylate oligomer is preferably 40% by weight to 100% by weight with respect to the total curable compound in the composition for forming a hard coat layer. Preferably they are 50 weight%-95 weight%, Especially preferably, they are 60 weight%-90 weight%. If it is such a range, the hard-coat layer excellent in hardness and adhesiveness with a base material layer can be formed.

  The composition for forming a hard coat layer may contain a monofunctional monomer as a curable compound. A monofunctional monomer easily penetrates into a thermoplastic resin film (for example, a (meth) acrylic resin film). Therefore, if the monofunctional monomer is contained, the adhesion between the thermoplastic resin film and the hard coat layer is excellent. And the optical laminated body by which interference nonuniformity was suppressed can be obtained. The content ratio of the monofunctional monomer is preferably 40% by weight or less, more preferably 30% by weight or less, and particularly preferably 20% by weight with respect to the total curable compound in the hard coat layer forming composition. It is as follows. When the content ratio of the monofunctional monomer is more than 40% by weight, desired hardness and scratch resistance may not be obtained.

  The hard coat layer forming composition preferably contains any appropriate photopolymerization initiator. Examples of the photopolymerization initiator include 2,2-dimethoxy-2-phenylacetophenone, acetophenone, benzophenone, xanthone, 3-methylacetophenone, 4-chlorobenzophenone, 4,4′-dimethoxybenzophenone, benzoinpropyl ether, benzyldimethyl Ketals, N, N, N ′, N′-tetramethyl-4,4′-diaminobenzophenone, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, thioxanthone compounds, etc. Can be mentioned.

  The composition for forming a hard coat layer may further contain any appropriate additive. Examples of additives include leveling agents, anti-blocking agents, dispersion stabilizers, thixotropic agents, antioxidants, UV absorbers, antifoaming agents, thickeners, dispersants, surfactants, catalysts, fillers, and lubricants. And antistatic agents.

  As said leveling agent, a fluorine type or silicone type leveling agent is mentioned, for example, Preferably, it is a silicone type leveling agent. Examples of the silicone leveling agent include reactive silicone, polydimethylsiloxane, polyether-modified polydimethylsiloxane, and polymethylalkylsiloxane. Of these, reactive silicone is preferable. If reactive silicone is added, the surface of the hard coat layer is provided with slipperiness and the scratch resistance is maintained for a long period of time. The content of the leveling agent is preferably 5% by weight or less, more preferably 0.01% by weight to 5% by weight, based on the total curable compound in the composition for forming a hard coat layer.

  The composition for forming a hard coat layer may or may not contain a solvent. Examples of the solvent include dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, 1,4-dioxane, 1,3-dioxolane, 1,3,5-trioxane, tetrahydrofuran, acetone, methyl ethyl ketone (MEK). , Diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone (CPN), cyclohexanone, methylcyclohexanone, ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, ethyl acetate n -Pentyl, acetylacetone, diacetone alcohol, methyl acetoacetate, ethyl acetoacetate, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-pen Nord, 2-methyl-2-butanol, cyclohexanol, isopropyl alcohol (IPA), isobutyl acetate, methyl isobutyl ketone (MIBK), 2-octanone, 2-pentanone, 2-hexanone, 2-heptanone, 3-heptanone, ethylene Examples include glycol monoethyl ether acetate, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and propylene glycol monomethyl ether. These may be used alone or in combination.

  According to the present invention, the composition for forming a hard coat layer containing no solvent or the composition for forming a hard coat layer containing only the poor solvent for the thermoplastic resin film forming material as the solvent can be used. An object can permeate the thermoplastic resin film to form a permeation region having a desired thickness.

  The refractive index of the hard coat layer (refractive index on the surface on which the base material layer is not provided) is preferably 1.48 to 1.78.

  The pencil hardness (pencil hardness on the surface on which the base material layer is not provided) of the hard coat layer is preferably 2H or more.

  The thickness of the hard coat layer is preferably 3 μm to 30 μm, more preferably 5 μm to 20 μm.

E. Low Refractive Index Layer The low refractive index layer has a lower refractive index than the hard coat layer. By laminating the low refractive index layer on the hard coat layer, the antireflection property of the obtained optical laminate is improved. The refractive index of the low refractive index layer is preferably 1.20 to 1.45, more preferably 1.23 to 1.42.

  The low refractive index layer is typically formed by applying a composition for forming a low refractive index layer containing a binder component and low refractive index fine particles to the hard coat layer.

  The binder component may be a curable binder component that can be cured by heat, light (ultraviolet rays, etc.) or an electron beam, and does not react with heat, light (ultraviolet rays, etc.) or electron beams, and is dried or dried. It may be a non-curable binder component that is solidified by cooling. A curable binder component is preferably used.

  Any appropriate curable compound may be selected as the curable binder component. The curable compound may be any of a monomer, an oligomer and a prepolymer. Specific examples include curable fluororesins and the curable compounds described in Section D.

  Any appropriate fine particles may be used as the low refractive index fine particles. The refractive index of the low refractive index fine particles is, for example, 1.44 or less, preferably 1.20 to 1.44, more preferably 1.23 to 1.40. Examples of the low refractive index fine particles include fine particles having voids or fine particles formed of a low refractive index material.

  Examples of the fine particles having voids include hollow fine particles and porous fine particles. Examples of the material for forming fine particles having voids include metals, metal oxides, and resins. Among these, hollow silica fine particles can be preferably used. In the hollow silica fine particles, a lipophilic group or a reactive group may be introduced on the surface using a silane coupling agent.

  The material for forming the fine particles formed of the low refractive index material is not limited as long as the refractive index is satisfied, and examples thereof include metal fluorides such as magnesium fluoride, aluminum fluoride, calcium fluoride, and lithium fluoride. It is done.

  The average particle diameter (average primary particle diameter) of the low refractive index fine particles is, for example, 1 nm to 100 nm. If the average particle size is within the range, both transparency and dispersibility can be achieved.

  Regarding details of the low refractive index fine particles, descriptions in WO2008 / 038714, WO2009 / 025292 and the like can be referred to.

  The blending amount of the low refractive index fine particles is preferably 30% by weight to 250% by weight, more preferably 45% by weight to 200% by weight, and further preferably 60% by weight to 150% by weight with respect to the binder component. It is.

  The composition for forming a low refractive index layer preferably contains any appropriate photopolymerization initiator. Further, it may further contain a solvent and any appropriate additive as required. Specific examples of the photopolymerization initiator, the solvent and the additive include the same ones that can be used for the composition for forming a hard coat layer.

  The thickness of the low refractive index layer is, for example, 10 nm to 200 nm, preferably 20 nm to 120 nm.

F. 2. Manufacturing method of optical laminated body The manufacturing method of the optical laminated body of this invention includes apply | coating the composition for hard-coat layer formation on a thermoplastic resin film, forming an application layer, and heating this application layer. Preferably, the method further includes subjecting the composition for forming a hard coat layer to a curing treatment after the heating. When producing an optical laminate comprising a low refractive index layer, the composition for forming a low refractive index layer is applied on the coating layer after heating or the hard coat layer after curing, and optionally subjected to curing treatment. In addition. Preferably, the composition for forming a low refractive index layer is applied on the hard coat layer after the curing treatment, and the curing treatment is performed.

  Any appropriate method can be adopted as a method for applying the hard coat layer forming composition and the low refractive index layer forming composition. Examples thereof include a bar coating method, a roll coating method, a gravure coating method, a rod coating method, a slot orifice coating method, a curtain coating method, a fountain coating method, and a comma coating method.

  The heating temperature of the coating layer can be set to an appropriate temperature according to the composition of the hard coat layer forming composition, and is preferably set to be equal to or lower than the glass transition temperature of the resin contained in the thermoplastic resin film. When heated at a temperature not higher than the glass transition temperature of the resin contained in the thermoplastic resin film, an optical laminate in which deformation due to heating is suppressed can be obtained. The heating temperature of the coating layer is, for example, 80 ° C to 140 ° C. When heated at a temperature in such a range, the curable compound in the hard coat layer-forming composition penetrates and diffuses well into the thermoplastic resin film. Next, by performing a curing treatment, an optical laminate having excellent adhesion between the thermoplastic resin film and the hard coat layer and suppressing interference unevenness can be obtained. In addition, when the composition for hard-coat layer formation contains a solvent, the apply | coated composition for hard-coat layer formation can be dried by the said heating. Further, the penetration depth can be increased, for example, by setting the heating temperature high within the above range.

  In one embodiment, the heating temperature may be set according to the content ratio of the curable compound having two or more (meth) acryloyl groups and the monofunctional monomer. The more the curable compound and / or monofunctional monomer having two or more (meth) acryloyl groups contained in the composition for forming a hard coat layer, the lower the heating temperature (for example, 80 ° C to 100 ° C), It is possible to obtain an optical laminate having excellent adhesion and suppressing interference unevenness, and an efficient manufacturing process with a small environmental load can be achieved.

  Any appropriate curing process can be adopted as the curing process. Typically, the curing process is performed by ultraviolet irradiation. The integrated light quantity of ultraviolet irradiation is preferably 200 mJ to 400 mJ.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. The evaluation methods in the examples are as follows. In Examples, unless otherwise specified, “parts” and “%” are based on weight.

(1) Refractive index The refractive index of the base material layer and the hard coat layer was measured using an Abbe refractometer (trade name: DR-M2 / 1550) manufactured by Atago Co., Ltd., selecting monobromonaphthalene as an intermediate solution.
(2) Hard Coat Layer Thickness and Penetration Depth On the base layer side of the optical laminate obtained in the examples and comparative examples, a black acrylic plate (manufactured by Mitsubishi Rayon Co., Ltd., thickness 2 mm) and an acrylic system having a thickness of 20 μm It stuck through the adhesive. Next, the reflection spectrum of the hard coat layer was measured under the following conditions using an instantaneous multi-photometry system (trade name: MCPD3700, manufactured by Otsuka Electronics Co., Ltd.), and the thickness of the hard coat layer was evaluated from the peak position of the FFT spectrum. . In addition, the value measured by said (1) was used for the refractive index.
Reflection spectrum measurement conditions Reference: Mirror Algorithm: FFT method Calculation wavelength: 450 nm to 850 nm
・ Detection conditions Exposure time: 20 ms
Lamp gain: Normal Integration count: 10 times / FFT method Film thickness range: 2 to 15 μm
Film thickness resolution: 24nm
On the other hand, it evaluated by the said reflection spectrum measurement about the following laminated body (R1).
-Laminate (R1): Implemented except that a PET base material (trade name: U48-3, refractive index: 1.60) manufactured by Toray Industries, Inc. was used as the base film, and the heating temperature of the coating layer was 60 ° C Obtained in the same manner as in Example 1.
Since the composition for forming a hard coat layer does not penetrate into the PET substrate used for the laminate (R1), the thickness of the hard coat layer measured from the peak position of the FFT spectrum obtained from the laminate (R1) is: It becomes smaller by the penetration depth than the thickness of the hard coat layer of the optical laminate obtained in the examples and comparative examples. Therefore, the penetration depth is determined by subtracting (thickness of hard coat layer of laminate (R1)) from (thickness of hard coat layer of optical laminate obtained in Examples and Comparative Examples).
(3) Interference unevenness After a black acrylic plate (Mitsubishi Rayon Co., Ltd., thickness 2 mm) was attached to the base layer side of the optical laminate obtained in Examples and Comparative Examples via an acrylic adhesive, 3 Interference unevenness was visually observed under a wavelength fluorescent lamp and evaluated according to the following criteria.
○: No interference unevenness Δ: Some interference unevenness is observed, but there is no practical problem ×: Many interference unevenness is recognized and becomes a practical problem (4) Pencil hardness Example And the pencil hardness of the hard coat layer surface of the optical laminated body obtained by the comparative example was measured based on JISK5400, and the following references | standards evaluated.
○: 2H or more ×: H or less

<Production Example 1> Production of Base Film A 100 parts by weight of imidized MS resin (weight average molecular weight: 105,000) described in Production Example 1 of JP 2010-284840 A and triazine-based ultraviolet absorber (ADEKA) (Product name: T-712) 0.62 parts by weight were mixed at 220 ° C. with a twin-screw kneader to prepare resin pellets. The obtained resin pellets were dried at 100.5 kPa and 100 ° C. for 12 hours, extruded from a T-die at a die temperature of 270 ° C. with a single screw extruder, and formed into a film (thickness: 160 μm). Further, the film is stretched in an atmosphere of 150 ° C. in the transport direction (thickness 80 μm), and then stretched in an atmosphere of 150 ° C. in a direction orthogonal to the film transport direction to form a base film A (( (Meth) acrylic resin film). The base film A thus obtained had a light transmittance of 8.5% at a wavelength of 380 nm, an in-plane retardation Re of 0.4 nm, and a thickness direction retardation Rth of 0.78 nm. In addition, the moisture permeability of the obtained base film A was 61 g / m ² · 24 hr. The light transmittance was measured by measuring a transmittance spectrum in a wavelength range of 200 nm to 800 nm using a spectrophotometer (device name: U-4100) manufactured by Hitachi High-Tech Co., Ltd., and reading the transmittance at a wavelength of 380 nm. . The phase difference value was measured at a wavelength of 590 nm and 23 ° C. using a trade name “KOBRA21-ADH” manufactured by Oji Scientific Instruments. The moisture permeability was measured by a method according to JIS K 0208 under conditions of a temperature of 40 ° C. and a relative humidity of 92%.

<Example 1>
Urethane acrylate oligomer as curable compound (Daicel Ornex, product name “KRM8452”, Mw = 1200, functional group number: 10) 80 parts and pentaerythritol triacrylate (Osaka Organic Chemical Co., product name “Biscoat” # 300 ", Mw = 298) 20 parts and, ZrO ₂ fine particle-containing sol (manufactured by Nissan chemical Industries, Ltd., product name" Nanoyusu OZ-S30K ", solid content: 30%, average particle diameter: 10 nm, refractive index: 2.2 , Solvent: methyl isobutyl ketone), 0.5 part of a leveling agent (manufactured by DIC, trade name: PC4100), and 3 parts of a photopolymerization initiator (manufactured by Ciba Japan, trade name: Irgacure 907). Mix and dilute with methyl isobutyl ketone so that the solids concentration is 50%. Prepared.

On the base film A obtained in Production Example 1, the obtained composition for forming a hard coat layer was applied to form a coating layer, and the coating layer was heated at 100 ° C. for 1 minute. The heated coating layer was irradiated with ultraviolet rays having an integrated light amount of 300 mJ / cm ² with a high-pressure mercury lamp to cure the coating layer, thereby obtaining an optical laminate having a structure of [base material layer / hard coat layer].

<Example 2>
An optical laminate was obtained in the same manner as in Example 1 except that the amount of the ZrO ₂ fine particle-containing sol was 67 parts.

<Example 3>
An optical laminate was obtained in the same manner as in Example 1 except that the blending amount of the ZrO ₂ fine particle-containing sol was 133 parts.

<Example 4>
_Sb 2 _{O 5} fine particle-containing sol in place of ZrO ₂ fine particle-containing sol 100 parts (JGC Catalysts and Chemicals Ltd., trade name "ELCOM V-4562", solid content: 30%, average particle diameter: 15 nm, refractive index: 1. (7, solvent: methyl isobutyl ketone) An optical laminate was obtained in the same manner as in Example 1 except that 133 parts were used.

<Example 5>
Urethane acrylate oligomer (product name “UV1700B”, product name “UV1700B”, Mw = 2000, functional group number: 10) 70 parts as a curable compound and pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., product name “Biscoat #” 300 ”, Mw = 298) 30 parts were used, and an optical laminate was obtained in the same manner as in Example 1 except that the amount of the ZrO ₂ fine particle-containing sol was 133 parts.

<Example 6>
100 parts of urethane acrylate oligomer (manufactured by Nippon Synthetic Chemical Co., Ltd., product name “UV1700B”, Mw = 2000, number of functional groups: 10) was used as the curable compound, and the blending amount of the ZrO ₂ fine particle-containing sol was 133 parts. In addition, an optical laminate was obtained in the same manner as in Example 1 except that the heating temperature of the coating layer was set to 110 ° C.

<Comparative Example 1>
100 parts of pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., product name “Biscoat # 300”, Mw = 298) was used as the curable compound, and the blending amount of the ZrO ₂ fine particle-containing sol was 133 parts. Except for this, an optical layered body was obtained in the same manner as in Example 1.

<Comparative example 2>
100 parts of dipentaerythritol hexaacrylate (DPHA) (manufactured by Shin-Nakamura Chemical Co., Ltd., product name “A-DPH”, Mw = 578) was used as the curable compound, and the blending amount of the ZrO ₂ fine particle-containing sol was 133 parts. An optical laminate was obtained in the same manner as in Example 1 except that the heating temperature of the coating layer was 110 ° C.

<Comparative Example 3>
Urethane acrylate oligomer (product name “KRM7804”, Mw = 3000, functional group number: 9) 100 parts was used as the curable compound, and the amount of ZrO ₂ fine particle-containing sol was 133 parts. In addition, an optical layered body was obtained in the same manner as in Example 1 except that the heating temperature of the coating layer was 110 ° C.

<Comparative Example 4>
Use of 154 parts of urethane acrylate oligomer (product name “UV7620EA”, solid content: 65%, Mw = 4100, number of functional groups: 9) as a curable compound, blend of ZrO ₂ fine particle-containing sol An optical layered body was obtained in the same manner as in Example 1 except that the amount was 133 parts and the heating temperature of the coating layer was 110 ° C.

The optical laminates obtained in the examples and comparative examples were subjected to the evaluations (1) to (4) above. The results are shown in Table 1.

  As is clear from Table 1, the optical laminate of the present invention has suppressed interference unevenness and sufficient hardness. Moreover, since it can manufacture with 1 coat, manufacture is easy. In addition, when the cross section of the optical laminated body obtained in each Example was observed with a TEM, the hard coat layer was not phase-separated, and the high refractive index fine particles were on the surface on which the base material layer was not provided. The segregation was such that the concentration continuously decreased in the thickness direction. A TEM photograph of a cross section of the hard coat layer of the optical layered body of Example 1 is shown in FIGS. As shown in FIG. 3A, the hard coat layer of the optical laminate of Example 1 is not phase-separated, and the high refractive index fine particles are segregated on the side where the base material layer is not provided. Furthermore, as shown in FIG. 3B, which is a partially enlarged photograph of FIG. 3A, the high refractive index fine particles are concentrated from the surface on the side where the base material layer is not provided toward the base material layer side. Are distributed so as to be continuously lower.

  Moreover, the reflection spectrum of the optical laminated body of Example 1 and the optical laminated body of Comparative Example 3 was measured under the same conditions as the measurement of the thickness of the hard coat layer except that the calculation wavelength was 380 nm to 780 nm. The results are shown in FIG. As shown in FIG. 4, the optical layered body of Example 1 has a smooth reflection spectrum and no interference unevenness. On the other hand, in the optical laminated body of Comparative Example 3, the reflection spectrum is wavy, and it can be seen that there is interference unevenness. The reason why the reflection spectrum of the optical laminated body of Comparative Example 3 has such a shape is that the optical laminated body has two interfaces having different refractive indexes (that is, a phase separation interface in the hard coat layer, a hard coat layer and a base). This is probably because there is an interface with the material layer. That is, the shape of the reflection spectrum of the optical laminate of Comparative Example 3 is a result of light recognizing the phase separation interface in the hard coat layer, and the high refractive index particles are uniformly dispersed in the upper layer. Recognize.

[Reference Example 1]
An optical laminate T1 was obtained in the same manner as in Example 1 except that the high refractive index fine particle-containing sol was not added.

[Reference Example 2]
An optical laminate T2 was obtained in the same manner as in Comparative Example 3 except that the high refractive index fine particle-containing sol was not added.

  TEM photographs of cross sections of the optical laminates T1 and T2 are shown in FIGS. 5A and 5B, respectively. As shown in FIG. 5, no phase separation occurs in the hard coat layer of the optical laminate T1. On the other hand, phase separation occurs in the hard coat layer of the optical laminate T2.

  The optical layered body of the present invention can be suitably used for an image display device. The optical layered body of the present invention can be suitably used as a front plate of an image display device or a protective material for a polarizer, and particularly suitably used as a front plate of a liquid crystal display device (in particular, a three-dimensional liquid crystal display device). obtain.

DESCRIPTION OF SYMBOLS 10 Base material layer 20 Hard-coat layer 22 Penetration area | region 30 Low-refractive-index layer 100,200 Optical laminated body

Claims (8)

A base material layer formed from a thermoplastic resin film;
A hard coat layer formed by applying a composition for forming a hard coat layer containing a curable compound having a molecular weight of 600 to 2500 and high refractive index fine particles having a refractive index of 1.50 or more to the thermoplastic resin film. And comprising
The hard coat layer includes an infiltration region formed by infiltrating the thermoplastic resin film with the hard coat layer forming composition;
The high refractive index fine particles are segregated in the hard coat layer so that the concentration continuously decreases in the thickness direction from the surface on which the base material layer is not provided .
An optical laminate in which the high refractive index fine particles are metal oxide fine particles .   The optical laminated body of Claim 1 in which the said curable compound contains the oligomer of urethane (meth) acrylate and / or urethane (meth) acrylate.   The optical laminate according to claim 1, wherein phase separation does not occur in the hard coat layer.   The optical laminated body in any one of Claim 1 to 3 whose said thermoplastic resin film is a (meth) acrylic-type resin film.   The hard coat layer includes a thermoplastic resin that forms the thermoplastic resin film so that the concentration continuously decreases in the thickness direction from the base layer side surface. The optical laminated body as described.   The optical laminate according to any one of claims 1 to 5, further comprising a low refractive index layer on a side of the hard coat layer on which the base material layer is not provided.   The polarizing film containing the optical laminated body in any one of Claim 1 to 6. The image display apparatus containing the optical laminated body in any one of Claim 1 to 6.