JP2013246371A - Optical laminate, polarizing plate and image display apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical laminate capable of highly suppressing generation of rainbow-like irregularities and interference fringes on a display image in a liquid crystal display device using a light-permeable base material having an in-plane birefringence and to provide a polarizing plate and an image display device using the optical laminate.SOLUTION: There is provided an optical laminate which has an optical functional layer having an unevenness shape on a surface, on one surface of a light-permeable base material having an in-plane birefringence, wherein the light-permeable base material having an in-plane birefringence has a retardation of 3000 nm or more, and in the uneven shape on the surface of the optical functional layer, when the average tilt angle of the uneven part is defined as θa and the skewness of the unevenness is defined as Sk, the absolute value of Sk and θa satisfy the following expression: 0.01°≤θa≤0.10°|Sk|≤0.5.

Description

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

Since liquid crystal display devices have features such as power saving, light weight, and thinness, they have rapidly spread in recent years in place of conventional CRT displays.
In such a liquid crystal display device, a polarizer is disposed on the image display surface side of the liquid crystal cell, and it is usually required to give hardness so that the polarizer is not damaged during handling. As a plate protective film, it is a general practice to impart hardness to the image display surface by using a hard coat film in which a hard coat layer is provided on a light transmissive substrate.

Conventionally, a film made of a cellulose ester typified by triacetyl cellulose has been used as a light-transmitting substrate of such a hard coat film. This is because cellulose ester is excellent in transparency and optical isotropy, and has almost no retardation in the plane (low retardation value). Because it has little influence on the display quality of the device and has a suitable water permeability, moisture remaining in the polarizer when the polarizing plate using the optical laminate is produced can be dried through the optical laminate. It is based on advantages such as being able to.
However, the cellulose ester film is a disadvantageous material in terms of cost, and has insufficient moisture resistance and heat resistance. When a hard coat film is used as a polarizing plate protective film in a hot and humid environment, the polarizing function and hue There is a disadvantage that the polarizing plate function is lowered.

Because of these problems with cellulose ester films, light that replaces cellulose ester films for polyester substrates such as polyethylene terephthalate, which is excellent in transparency, heat resistance, mechanical strength, and cheaper than cellulose ester films. Attempts have been made to use it as a material for a permeable substrate.
However, polyethylene terephthalate film has an aromatic ring with high polarizability in the molecular chain, so the intrinsic birefringence is extremely large, and the molecular chain orientation by stretching treatment to give excellent transparency, heat resistance and mechanical strength. Along with this, film birefringence tends to develop. For this reason, when arranged on a polarizing element, unevenness of different colors (hereinafter also referred to as “Nizimura”) occurs in the liquid crystal display device, particularly when the display screen is observed obliquely, and the display quality of the liquid crystal display device is impaired. There was a problem that would be.

As an attempt to use a polyester base material as a material for a light-transmitting base material in place of a cellulose ester film, for example, Patent Document 1 discloses that an in-plane retardation Re is 500 nm or more as a film mainly containing a polyester resin. A polarizing plate protective film is described. In the invention described in Patent Document 1, the polyester film is inevitably stretched biaxially so that the longitudinal and lateral stretch ratios are 3.3 / 3.9 in order to give the polyester film sufficient mechanical strength. The retardation is low, and the stretching ratio is small, and the longitudinal and lateral stretching ratios are almost equal. Therefore, the retardation value is 500 nm at the minimum and 700 nm at the maximum. However, such a small retardation cannot solve the problem. Therefore, in the invention described in Patent Document 1, the Nidjira problem is solved by providing a light diffusion layer having a haze of 10 to 80% as the uppermost layer. However, if a light diffusing layer having a haze of 10% or more is provided, there is a problem that the image quality such as white blur and contrast is inferior even if the nitrile blur can be eliminated.

For example, Patent Document 2 describes an antiglare film using a polyethylene terephthalate film that is sufficiently transparent by stretching 2.5 to 6 times as a transparent substrate. In this antiglare film, if the retardation is 1000 or more, the coloration at the front becomes inconspicuous, but the color unevenness in the oblique direction (Nijimura) cannot be eliminated, so the total haze is 8 times or more of the transmission sharpness. By doing so, Nijimura is eliminated. However, since visibility will fall if a permeation | transmission clarity is low, the anti-glare film of patent document 2 needs 5.5 to 55% as a haze. Furthermore, in order to satisfy the relationship between the transmission definition and haze, the period of the surface irregularity is increased, and the regular reflectance of the antiglare layer is set to a very low value of 0.05 to 2%. Since there is almost no flat surface on the surface of the glare layer, there is a problem that the image quality including white blurring and contrast is inferior even if the wiggle can be eliminated.

Further, in Patent Document 3, a white light emitting diode is used as a light source, and an angle between an absorption axis of a polarizing plate and a slow axis of the polymer film is 45 degrees in a polymer film having a retardation of 3000 to 30000 nm. It is described that when the screen is observed through a polarizing plate such as sunglasses, good visibility can be ensured regardless of the observation angle. However, polyesters and polycarbonate films, which are preferable polymer films in Patent Document 3, are soft and have no scratch resistance, and thus cannot be put to practical use unless a hard coat layer is provided on the surface of the polymer film. However, when a hard coat layer is provided on the surface of the polymer film, if the difference in refractive index between the two becomes large, interference fringes due to the difference in refractive index occur, resulting in image quality degradation.

Here, interference fringes means that when white light strikes a transparent thin film, the light reflected from the surface of the thin film and the light that enters the thin film and reflects from the back side of the thin film cause interference, resulting in a partial iris shape. This is a phenomenon in which color is seen, and is a phenomenon that occurs because the wavelength that strengthens changes depending on the viewing direction. This phenomenon is not only difficult to see for the user but may give an unpleasant impression, and improvement is strongly demanded. When a hard coat layer (refractive index: Nh) is provided on a polymer film (refractive index: Np), when there is a difference (refractive index difference) between Np and Nh, for example, Np is 1.64-1. When Nh is 1.50 to 1.53 at 68, interference of reflected light occurs at the interface between the polymer film and the hard coat layer, and the interference fringes become more conspicuous as the refractive index difference is larger.
On the other hand, it is known that interference fringes can be eliminated by aligning the refractive indexes of the polymer film (refractive index: Np) and hard coat layer (refractive index: Nh) as much as possible (hereinafter also referred to as interference fringe elimination method). That is, even in the invention described in Patent Document 3, it is necessary to provide a hard coat layer based on the interference fringe elimination method in order to prevent interference fringes.
However, in Patent Document 3, in order to give a high retardation value to the polymer film, the refractive index in the longitudinal direction and the lateral direction of the polymer film (hereinafter also referred to as Nx and Ny, respectively, where Np- Nx = Ny−Np), the refractive index Nh of the hard coat layer based on the interference fringe elimination method cannot be determined, and even if Nh is an average value of Nx and Ny Even in this case, there are Nh-Nx and Nh-Ny refractive index differences in the vertical and horizontal directions, respectively, so that interference fringes cannot be eliminated. In other words, unless the thickness of the polymer film is increased, the greater the retardation, the greater the difference between Nx and Ny and Nh, and interference fringes become a greater problem.
That is, in Patent Document 3, the problem of image quality degradation due to the occurrence of interference fringes cannot be avoided.

JP 2008-003541 A JP 2009-156938 A JP2011-107198A

When the present inventors examined the problem in the case of using such a light-transmitting substrate such as a polyester film, retardation Re was disclosed in Patent Document 1 as a light-transmitting substrate of the optical laminate. By using a light-transmitting substrate having a birefringence in a plane having a value much larger than the value described, an optical laminate including a light-transmitting substrate made of a conventional polyester film or the like It has been found that the problem of rainbow-like unevenness can be improved as compared with the case of using it.

However, when a light-transmitting substrate having a birefringence in the plane having such a high retardation value is used, and an optical laminate having a hard coat layer provided on the light-transmitting substrate, the light-transmitting property is obtained. A primer layer is essential to ensure adhesion between the substrate and the hard coat layer. In the optical laminated body having such a configuration, the light-transmitting substrate generally has a high refractive index of 1.64 to 1.68, whereas the refractive index of the primer layer and the hard coat layer is high depending on some material. Unless the refractive index is changed, the refractive index is low, and the difference in refractive index between the light-transmitting substrate, the primer layer and the hard coat layer is large, causing rainbow-like interference fringes, which degrades the image quality of displays, etc. was there.

As a method for preventing the occurrence of 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. There is known a method of forming an impregnated layer obtained by impregnating the material of the hard coat layer in a light-transmitting substrate using a solvent that can swell or dissolve.
However, such a method is effective when the light-transmitting substrate is made of a specific material such as a material that is swollen or dissolved by the solvent, for example, a triacetyl cellulose substrate. Since such a light-transmitting substrate is hardly swollen or dissolved by the solvent, the method cannot be employed.

In view of the above situation, the present invention provides a liquid crystal display device using a light-transmitting substrate having a birefringence index in the plane, and is capable of highly suppressing the occurrence of azimuth irregularities and interference fringes in a display image. It is an object to provide a laminate, a polarizing plate and an image display device using the optical laminate.

The present invention provides an optical laminate having an optical functional layer having a concavo-convex shape on one surface of a light-transmitting substrate having a birefringence index in the plane, wherein the birefringence index is in the plane. The light-transmitting base material has a retardation of 3000 nm or more, and the uneven shape on the surface of the optical functional layer has an absolute value of Sk when the average inclination angle of the uneven portion is θa and the unevenness skewness is Sk. The optical laminate is characterized in that the value and θa satisfy the following formula.
0.01 ° ≦ θa ≦ 0.10 °
| Sk | ≦ 0.5

In the optical layered body of the present invention, the light-transmitting substrate having a birefringence in the plane has a refractive index (nx) in the slow axis direction that is a direction in which the refractive index is large, and is orthogonal to the slow axis direction. The difference (nx−ny) with respect to the refractive index (ny) in the fast axis direction, which is the direction in which the light is applied, is preferably 0.05 to 0.20.
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
In the present invention, the optical functional layer is preferably a hard coat layer.
In the present invention, the optical functional layer preferably has a structure in which a low refractive index layer is laminated on a hard coat layer.
The hard coat layer preferably contains inorganic oxide fine particles and a binder resin.
The inorganic oxide fine particles are preferably hydrophobized inorganic oxide fine particles.
The inorganic oxide fine particles form an aggregate and are contained in the hard coat layer, and the average particle diameter of the aggregate is preferably 100 nm to 2.0 μm.
The light-transmitting substrate having a birefringence in the plane is preferably a polyester substrate.
Further, the optical laminate of the present invention preferably has a total haze based on JIS K7136 of less than 2.0.

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 image display device of the present invention preferably includes a white light emitting diode as a backlight light source.
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 a transparent substrate having a birefringence in a plane such as a polyester substrate. By having a predetermined retardation value, it is possible to suppress the occurrence of azimuth irregularities in the display image, and furthermore, a specific uneven shape is formed on the surface of the optical function layer (the side opposite to the light-transmitting substrate). Thus, it has been found that the generation of interference fringes can be suitably prevented, and the present invention has been completed.
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.

The optical layered body of the present invention has an optical functional layer having a concavo-convex shape on one surface of a light-transmitting substrate having a birefringence index in the plane.
The light-transmitting substrate having a birefringence in the plane is not particularly limited, and examples thereof include substrates made of polycarbonate, cycloolefin polymer, acrylic, polyester, etc. Among them, cost and mechanical strength are mentioned. It is preferred that the polyester base is advantageous. In the following description, a light-transmitting substrate having a birefringence in the plane will be described as a polyester substrate.

The polyester base material has a retardation of 3000 nm or more. If the retardation is less than 3000 nm, Nizimura appears in the display image of the liquid crystal display device using the antiglare film of the present invention. On the other hand, the upper limit of the retardation of the polyester base material is not particularly limited, but is preferably about 30,000 nm. If it exceeds 30,000 nm, no further improvement in the effect of improving the azimuth of the display image is observed, and the film thickness becomes considerably thick.
The retardation of the polyester base material is more preferably from 6000 to 25000 nm from the viewpoint of preventing azimuth and thinning. A more preferable range is 8000 to 20,000 nm.

The retardation is the refractive index (nx) in the direction having the highest refractive index (slow axis direction) in the plane of the polyester substrate, and the refraction in the direction orthogonal to the slow axis direction (fast axis direction). It is represented by the following formula by the rate (ny) and the thickness (d) of the polyester base material.
Retardation (Re) = (nx−ny) × d
The retardation can be measured, for example, by KOBRA-WR manufactured by Oji Scientific Instruments (measurement angle 0 °, measurement wavelength 548.2 nm).
In addition, a refractive index measures the average reflectance (R) of wavelength 380-780 nm using a spectrophotometer (Shimadzu Corporation UV-3100PC), From the obtained average reflectance (R), it is the following. The value of the refractive index (n) was obtained using the following formula.
The average reflectance (R) of the optical functional layer is a surface (back surface) on which 50 μm PET without easy adhesion treatment is coated with each raw material composition to form a cured film having a thickness of 1 to 3 μm, and PET is not applied. Then, in order to prevent back surface reflection, a black vinyl tape having a width larger than the measurement spot area (for example, Yamato vinyl tape NO200-38-21 38 mm width) was applied, and the average reflectance of each cured film was measured. The refractive index of the polyester base material was measured after black vinyl tape was similarly applied to the surface opposite to the measurement surface.
R (%) = (1-n) ² / (1 + n) ²
Further, as a method for measuring the refractive index of the optical functional layer after becoming an optical layered product, a cured film of each layer is scraped off with a cutter or the like to prepare a powder sample, and JIS K7142 (2008) B method (powder) Alternatively, the Becke method (for a granular transparent material) (using a Cargill reagent with a known refractive index, place the powdered sample on a glass slide, drop the reagent on the sample, and immerse the sample in the reagent. This is observed by microscopic observation, and a bright line generated in the sample outline due to the difference in refractive index between the sample and the reagent; a method in which the refractive index of the reagent in which the Becke line cannot be visually observed is used as the refractive index of the sample) is used. be able to.
In the case of a polyester base material, the refractive index varies depending on the direction. Therefore, instead of the Becke method, the black vinyl tape is attached to the treated surface of the optical functional layer, and the average reflectance is measured and determined.
In the present invention, the nx-ny (hereinafter also referred to as Δn) is preferably 0.05 to 0.20. If the Δn is less than 0.05, a sufficient nitrile suppression effect may not be obtained, and the film thickness necessary for obtaining the retardation value described above may be increased. On the other hand, if the above Δn exceeds 0.20, the polyester base material is likely to be torn and torn, and the practicality as an industrial material may be significantly reduced.
A more preferable lower limit of Δn is 0.07, and a more preferable upper limit is 0.15. This is because if the above Δn is smaller than 0.07, the effect of preventing azimuth unevenness when the slow axis is adjusted to 0 ° or 90 ° with respect to the polarizing plate absorption axis becomes difficult. In addition, when said (DELTA) n exceeds 0.15, the durability of the polyester base material in a heat-and-moisture resistance test may be inferior. Since the durability in the heat and humidity resistance test is excellent, the more preferable upper limit of Δn is 0.12.
In addition, as said (nx), it is preferable that it is 1.67-1.78, a more preferable minimum is 1.69 and a more preferable upper limit is 1.73. Moreover, as said (ny), it is preferable that it is 1.55-1.65, a more preferable minimum is 1.57 and a more preferable upper limit is 1.62.
When nx and ny are in the above-described range and satisfy the above-described relationship of Δn, it is possible to obtain a suitable nitrile suppression effect.

The material constituting the polyester base material is not particularly limited as long as it satisfies the retardation described above, but is synthesized from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. Examples include linear saturated polyester. Specific examples of such polyester include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly (1,4-cyclohexylenedimethylene terephthalate), and polyethylene-2,6-naphthalate.
The polyester used for the polyester substrate may be a copolymer of these polyesters. The polyester is mainly used (for example, a component of 80 mol% or more), and a small proportion (for example, 20 mol% or less). It may be blended with these types of resins. Polyethylene terephthalate or polyethylene-2,6-naphthalate is particularly preferable as the polyester because it has a good balance between mechanical properties and optical properties. In particular, it is preferably made of polyethylene terephthalate (PET). This is because polyethylene terephthalate is highly versatile and easily available. In the present invention, an optical laminate that can produce a liquid crystal display device with high display quality can be obtained even with a highly versatile film such as PET. Furthermore, PET is excellent in transparency, heat or mechanical properties, can control the retardation by stretching, has a large intrinsic birefringence, and can obtain a large retardation relatively easily even when the film thickness is small.

The method for obtaining the polyester base material is not particularly limited as long as the above-described retardation is satisfied. For example, the polyester, such as PET, as a material is melted and extruded into a sheet to form glass. The method of heat-processing after transverse stretching using a tenter etc. at the temperature more than transition temperature is mentioned.
The transverse stretching temperature is preferably 80 to 130 ° C, more preferably 90 to 120 ° C. Further, the transverse draw ratio is preferably 2.5 to 6.0 times, more preferably 3.0 to 5.5 times. When the transverse draw ratio exceeds 6.0 times, the transparency of the resulting polyester base material tends to be lowered, and when the draw ratio is less than 2.5 times, the draw tension becomes small. The birefringence of the material becomes small, and the retardation may not be 3000 nm or more.
In the present invention, the unstretched polyester is subjected to transverse stretching under the above conditions using a biaxial stretching test apparatus, and then stretched in the flow direction with respect to the transverse stretching (hereinafter also referred to as longitudinal stretching). Also good. In this case, the longitudinal stretching preferably has a stretching ratio of 2 times or less. When the draw ratio of the above-mentioned longitudinal stretching exceeds twice, the value of Δn may not be within the preferred range described above.
The treatment temperature during the heat treatment is preferably 100 to 250 ° C, more preferably 180 to 245 ° C.

Examples of the method for controlling the retardation of the polyester substrate produced by the above-described method to 3000 nm or more include a method of appropriately setting the draw ratio, the drawing temperature, and the film thickness of the produced polyester substrate. Specifically, for example, the higher the stretching ratio, the lower the stretching temperature, and the thicker the film, the easier it is to obtain high retardation. The lower the stretching ratio, the higher the stretching temperature, and the film thickness. The thinner, the easier it is to obtain low retardation.

The thickness of the polyester substrate is preferably in the range of 40 to 500 μm. When the thickness is less than 40 μm, the retardation of the polyester base material cannot be increased to 3000 nm or more, the anisotropy of mechanical properties becomes remarkable, and tearing, tearing, and the like easily occur, and the practicality as an industrial material is remarkably reduced. Sometimes. On the other hand, if it exceeds 500 μm, the polyester base material is very rigid, the flexibility specific to the polymer film is lowered, and the practicality as an industrial material is also lowered, which is not preferable. The minimum with more preferable thickness of the said polyester base material is 50 micrometers, a more preferable upper limit is 400 micrometers, and a still more preferable upper limit is 300 micrometers.

The polyester base material preferably has a transmittance in the visible light region of 80% or more, more preferably 84% or more. In addition, the said transmittance | permeability can be measured by JISK7361-1 (The test method of the total light transmittance of a plastic-transparent material).

In the present invention, the polyester substrate may be subjected to surface treatment such as saponification treatment, glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, and flame treatment without departing from the spirit of the present invention. Good. It is also preferable to provide a primer layer in terms of improving adhesion and further improving interference fringes.

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.
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 portion as θa and the skewness of the concavo-convex portion as Sk. To meet.
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 uneven portion is 0.01 °. If it is less than 0.01 °, the inclination is not sufficient and interference fringes cannot be prevented. A more preferred lower limit is 0.03 °, and a still more preferred lower limit is 0.04 °. The upper limit of the average inclination angle θa of the uneven portion is 0.10 °. If it exceeds 0.10 °, the angle of inclination of the concavo-convex portion is excessively large, which causes 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 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 lower limit of the arithmetic average roughness Ra of the unevenness is 0.02 μm. 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 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 possibility that a cloudiness is observed. If the average wavelength λa is more than 800 μm, the change in the inclination angle on the uneven surface is reduced, and there is a possibility that interference fringes cannot be suitably prevented. 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.

ここで、ｌは基準長さを表し、ｆ（ｘ）は粗さ曲線を表し、Ｒｑは二乗平均平方根粗さであり下記の式により定義される。

このようなθａ、Ｓｋ、Ｒａ及びＲｚは、例えば、表面粗さ測定器：ＳＥ−３４００／株式会社小坂研究所製等により測定して求めることができる。 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.

The optical functional layer preferably contains inorganic oxide fine particles.
The inorganic oxide fine particle is a material that forms an uneven shape on the surface of the optical functional layer. In the optical laminate of the present invention, the inorganic oxide fine particle forms an aggregate in the optical functional layer. It is preferable that the irregular shape of the surface of the optical functional layer is formed by the aggregate of the inorganic oxide fine particles.
Examples of the inorganic oxide fine particles include silica fine particles, alumina fine particles, zirconia fine particles, titania fine particles, tin oxide fine particles, ATO particles, and zinc oxide fine particles.

The inorganic oxide fine particles are preferably surface-treated. Since the inorganic oxide fine particles are surface-treated, the distribution of the aggregates of the inorganic oxide fine particles in the optical functional layer can be suitably controlled, and the chemical resistance of the inorganic oxide fine particles themselves And improvement of saponification resistance.

The surface treatment is preferably a hydrophobizing treatment, and examples thereof include a method of treating the inorganic oxide fine particles with a silane compound having a methyl group or an octyl group.
Here, a hydroxyl group is usually present on the surface of the inorganic oxide fine particle, but the surface treatment reduces the hydroxyl group on the surface of the inorganic oxide fine particle, and the BET method of the inorganic oxide fine particle. As a result, the inorganic oxide fine particles can be prevented from agglomerating excessively, and the above-described specific uneven shape can be formed on the surface of the optical functional layer.

The inorganic oxide fine particles are preferably amorphous. If the inorganic oxide fine particles are crystalline, the Lewis acidity of the inorganic oxide fine particles becomes strong due to lattice defects contained in the crystal structure, and excessive aggregation of the inorganic oxide fine particles cannot be controlled. is there.

As such inorganic oxide fine particles, for example, fumed silica is preferably used because it tends to aggregate itself and easily form an aggregate described later. 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. Specifically, AEROSIL R805 (made by Nippon Aerosil Co., Ltd.) etc. are mentioned, for example.

Although it does not specifically limit as content of the said inorganic oxide fine particle, It is preferable that it is 0.1-5.0 mass% in the said optical function layer. When the amount is less than 0.1% by mass, the above-described specific uneven shape cannot be formed on the surface of the optical function layer, and interference fringes may not be prevented. This causes internal diffusion and / or large surface irregularities in the optical functional layer, which may cause a problem of cloudiness. A more preferable lower limit is 0.5% by mass, and a more preferable upper limit is 3.0% by mass.

The inorganic oxide fine particles preferably have an average primary particle diameter of 1 to 100 nm. When the thickness is less than 1 nm, the above-described specific uneven shape may not be formed on the surface of the optical functional layer. When the thickness exceeds 100 nm, light is diffused by the inorganic oxide fine particles, and an image using the optical laminate of the present invention is used. The dark room contrast of the display device may be inferior. A more preferred lower limit is 5 nm, and a more preferred upper limit is 50 nm.
In addition, the average primary particle diameter of the inorganic oxide fine particles is measured using an image processing software from an image of a cross-sectional electron microscope (a transmission type such as TEM or STEM and preferably a magnification of 50,000 times or more). Value.

The inorganic oxide fine particles preferably have a spherical shape in a single particle state. Since the single particle of the inorganic oxide 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.

In the present invention, the aggregate of inorganic oxide fine particles preferably has a structure in which the inorganic oxide fine particles described above are connected in a bead shape (pearl necklace shape) in the optical functional layer.
By forming an aggregate in which the inorganic oxide fine particles are arranged in a bead shape in the optical functional layer, the convex portion based on the aggregate has a gentle shape with little inclination. It becomes easy to make the surface uneven shape into the specific uneven shape described above.
The structure in which the inorganic oxide fine particles are connected in a bead shape is, for example, a structure in which the inorganic oxide fine particles are continuously connected in a straight line (linear structure), a structure in which a plurality of the linear structures are entangled, Any structure such as a branched structure having one or two or more side chains in which a plurality of inorganic oxide fine particles are continuously formed in the linear structure is mentioned.

In addition, the aggregate of the inorganic oxide fine particles preferably has an average particle diameter of 100 nm to 2.0 μm. When the thickness is less than 100 nm, the above-described specific uneven shape may not be formed on the surface of the optical functional layer. When the thickness exceeds 2.0 μm, light is diffused by the aggregate of the inorganic oxide fine particles, and the optical characteristics of the present invention. The dark room contrast of an image display device using a laminate may be inferior. The more preferable lower limit of the average particle diameter of the aggregate is 200 nm, and the more preferable upper limit is 1.5 μm.
The average particle diameter of the aggregates of the inorganic oxide fine particles is selected from a 5 μm square region containing a large amount of aggregates of inorganic oxide fine particles from observation with a cross-sectional electron microscope (about 10,000 to 20,000 times). The particle diameters of the aggregates of the inorganic oxide fine particles in the region are measured, and the particle diameters of the aggregates of the top 10 inorganic oxide fine particles are averaged. The “particle diameter of the aggregate of the inorganic oxide fine particles” is the maximum distance between the two straight lines when the cross section of the aggregate of the inorganic oxide fine particles is sandwiched between any two parallel straight lines. It is measured as the distance between straight lines in a combination of two straight lines. The particle diameter of the aggregate of the inorganic oxide fine particles may be calculated using image analysis software.

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 inorganic oxide fine particles are preferably dispersed in a binder resin.
The binder resin preferably has a polarity adjusted according to the hydrophobicity of the hydrophobized inorganic oxide 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 inorganic oxide fine particles is suitably controlled, and the above-described specific uneven shape can be easily formed.

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.
In the present specification, “resin” is a concept including monomers, oligomers, polymers and the like unless otherwise specified.

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 inorganic oxide fine particles and the binder resin is obtained by, for example, applying the composition for a hard coat layer containing the above-described inorganic oxide fine particles, the monomer component of the binder resin, and a solvent on the light-transmitting substrate. The coating film formed by applying and drying can be formed by curing 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. By selecting the solvent relative evaporation rate, solid content concentration, coating solution temperature, drying temperature, drying air velocity, drying time, solvent atmosphere concentration in the drying zone, etc., the distribution state of the aggregates of inorganic oxide fine particles can be determined. Can be adjusted.
In particular, a method of adjusting the distribution state of the aggregates of inorganic oxide fine particles 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 inorganic oxidation is performed by performing the drying treatment appropriately adjusted within this range once or a plurality of times. It is possible to adjust the distribution state of the aggregates of the product fine particles 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 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. More 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 contains, for example, inorganic oxide fine particles, a binder resin monomer component, and a solvent on a light-transmitting substrate. It can manufacture by forming a hard-coat layer using a thing. Further, when the optical functional layer has a structure in which a low refractive index layer is laminated on the hard coat layer, it contains, for example, inorganic oxide fine particles, a monomer component of a binder resin, and a solvent on a light-transmitting substrate. After the hard coat layer is formed using the hard coat layer composition, it can be produced by forming the low refractive index layer on the hard coat layer using the low refractive index layer composition described 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.

Here, in the case where the present invention is a liquid crystal display device having the optical laminate, the optical laminate has absorption of the slow axis of the optical laminate and the polarizing plate (polarizing plate installed on the viewing side of the liquid crystal cell). When the angle formed with the axis is set to 45 ° ± 15 °, good visibility can be obtained even when the liquid crystal display device is observed through a polarizing plate such as sunglasses.
In the case where the present invention is a liquid crystal display device having the optical layered body, the optical layered body absorbs the slow axis of the optical layered body and the polarizing plate (the polarizing plate disposed on the viewing side of the liquid crystal cell). More preferably, the angle formed with the shaft is 0 ° ± 30 ° or 90 ° ± 30 °. When the angle formed by the slow axis of the optical laminate and the absorption axis of the polarizing plate is within the above range, it is possible to extremely highly suppress the occurrence of nitrite in the display image of the liquid crystal display device of the present invention. it can. The reason for this is not clear, but is thought to be due to the following reasons.
That is, in an environment free from outside light or fluorescent light (hereinafter, this environment is also referred to as “dark place”), the slow axis of the optical laminate of the liquid crystal display device of the present invention and the absorption of the polarizing plate It is possible to suppress the occurrence of azimuth unevenness regardless of the angle formed with the shaft. However, in an environment where there is ambient light or fluorescent light (hereinafter, this environment is also referred to as “light place”), external light or fluorescent light has only a continuous wide spectrum. Therefore, if the angle formed by the slow axis of the optical laminate and the absorption axis of the polarizing plate is not within the above-described range, nitrile occurs and the display quality deteriorates.
Furthermore, since the backlight light transmitted through the color filter is not limited to one having a continuous wide spectrum, the angle formed by the slow axis of the optical laminate and the absorption axis of the polarizing plate must be within the above range. It is estimated that the display quality deteriorates due to the occurrence of Nizimura.

In the liquid crystal display device of the present invention, the backlight light source is not particularly limited, but is preferably a white light emitting diode (white LED).
The white LED is an element that emits white by combining a phosphor with a phosphor system, that is, a light emitting diode that emits blue light or ultraviolet light using a compound semiconductor. Above all, white light-emitting diodes, which consist of light-emitting elements that combine blue light-emitting diodes using compound semiconductors with yttrium, aluminum, and garnet yellow phosphors, have a continuous and broad emission spectrum. Therefore, it is suitable for the backlight light source in the present invention. Further, since white LEDs with low power consumption can be widely used, it is possible to achieve an energy saving effect.

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-described antiglare film is also 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 antiglare film described above is provided on the 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, in a liquid crystal display device using a light-transmitting base material having a birefringence in the plane, azimuth irregularities and interference fringes are generated in a display image. It can be highly suppressed.
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.

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.
The retardation of the polyester substrate is obtained by using two polarizing plates to determine the orientation axis direction of the film, and the refractive index (nx, ny) of two axes perpendicular to the orientation axis direction is measured by Abbe refractometer ( It was obtained by Atago Co., Ltd. NAR-4T. Here, an axis showing a larger refractive index is defined as a slow axis. The film thickness d (nm) was measured using an electric micrometer (manufactured by Anritsu), and the unit was converted to nm. The retardation was determined from the product of the refractive index difference (nx−ny) and the film thickness d (nm).

Example 1
The polyethylene terephthalate material was melted at 290 ° C., extruded through a film-forming die, into a sheet form, closely adhered onto a water-cooled and cooled rotating quenching drum, and cooled to produce an unstretched film. This unstretched film was preheated at 120 ° C. for 1 minute with a biaxial stretching test apparatus (manufactured by Toyo Seiki Co., Ltd.), and then stretched at 120 ° C. at a stretch ratio of 4.5 times. Stretching was performed at a draw ratio of 1.5 times in the direction of the degree to obtain a polyester base material having retardation = 9900 nm, film thickness = 100 μm, and (nx−ny) = 0.099.

The composition for hard-coat layers of the composition shown below was apply | coated to the single side | surface of the obtained polyester base material, and the 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 coat 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 Synthetic Chemical Co., Ltd.) 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 (For example, octylsilane) is used to hydrophobize a silanol group with an octylsilyl group.

(Example 2)
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 1.5 parts by mass, and Example 1 was used except that the composition for hard coat layer was used. Similarly, an optical laminate according to Example 2 was produced.

(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, and Example 1 was used except that the composition for hard coat layer was used. Similarly, an optical laminated body according to Example 3 was produced.

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 used except that the composition for hard coat layer was used. Similarly, an optical laminated body according to Example 4 was produced.

(Example 5)
The composition for hard coat layers having the composition shown below was applied to one side of the polyester substrate obtained in Example 1 to form a coating film. 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 Synthetic Chemical Co., Ltd.) 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 (For example, octylsilane) is used to hydrophobize a silanol group with an octylsilyl group.

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 Ltd.) 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 used except that the composition for hard coat layer was used. Similarly, an optical laminate according to Example 6 was produced.

(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 used except that the composition for hard coat layer was used. Similarly, an optical laminate according to Example 7 was produced.

(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. Similarly, an optical laminated body according to Example 8 was produced.

Example 9
The stretch ratio of the unstretched film obtained in the same manner as in Example 1 was adjusted to obtain a polyester substrate having retardation = 3500 nm, film thickness = 42 μm, and (nx−ny) = 0.083. An optical laminate according to Example 9 was produced in the same manner as in Example 1 except that the obtained polyester substrate was used.

(Example 10)
The stretch ratio of the unstretched film obtained in the same manner as in Example 1 was adjusted to obtain a polyester base material with retardation = 19000 nm, film thickness = 190 μm, and (nx−ny) = 0.10. An optical laminate according to Example 10 was produced in the same manner as in Example 1 except that the obtained polyester substrate was used.

(Comparative Example 1)
A hard coat layer composition was prepared in the same manner as in Example 1 except that no fumed silica was blended, and Comparative Example 1 was carried out in the same manner as in Example 1 except that the hard coat layer composition was used. The optical laminated body which concerns on was produced.

(Comparative Example 2)
Except that 3 parts by mass of organic fine particles (hydrophilic treatment acrylic-styrene copolymer particles, average particle size 2.0 μm, refractive index 1.55, manufactured by Sekisui Plastics Co., Ltd.) was added, the same procedure as in Example 1 was performed. An optical laminate according to Comparative Example 2 was produced in the same manner as in Example 1 except that a composition for hard coat layer was prepared and that the composition for hard coat layer was used.

(Comparative Example 3)
The same as in Example 1 except that 1.5 parts by mass of organic fine particles (hydrophilic treatment acrylic-styrene copolymer particles, average particle size 2.0 μm, refractive index 1.515, manufactured by Sekisui Plastics Co., Ltd.) was added. Then, an optical laminate according to Comparative Example 3 was produced in the same manner as in Example 1 except that the composition for hard coat layer was prepared and the composition for hard coat layer was used.

(Comparative Example 4)
A hard coat layer composition 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 procedure as in Example 1 was conducted except that the hard coat layer composition was used. Thus, an optical laminate according to Comparative Example 4 was produced.

(Comparative Example 5)
A composition for a hard coat layer was prepared in the same manner as in Example 5 except that fumed silica was not blended, and Comparative Example 5 was prepared in the same manner as in Example 5 except that the composition for hard coat layer was used. The optical laminated body which concerns on was produced.

(Comparative Example 6)
Except that 3 parts by mass of organic fine particles (hydrophilic treatment acrylic-styrene copolymer particles, average particle size 2.0 μm, refractive index 1.55, manufactured by Sekisui Plastics Co., Ltd.) was added, the same procedure as in Example 5 was performed. An optical laminate according to Comparative Example 6 was produced in the same manner as in Example 5 except that a hard coat layer composition was prepared and the hard coat layer composition was used.

(Comparative Example 7)
The same as Example 5 except that 1.5 parts by mass of organic fine particles (hydrophilic treatment acrylic-styrene copolymer particles, average particle size 2.0 μm, refractive index 1.515, manufactured by Sekisui Plastics Co., Ltd.) was added. Then, an optical laminate according to Comparative Example 7 was produced in the same manner as in Example 5 except that the composition for hard coat layer was prepared and the composition for hard coat layer was used.

(Comparative 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 4 parts by mass, and the same procedure as in Example 5 was performed except that the composition for hard coat layer was used. Thus, an optical laminate according to Comparative Example 8 was produced.

(Comparative Example 9)
Optical lamination according to Comparative Example 9 in the same manner as in Example 1, except that Toyobo PET film A4100 with retardation = 2500 nm, film thickness = 75 μm, (nx−ny) = 0.033 was used as the polyester substrate. The body was made.

(Comparative Example 10)
The stretch ratio of the unstretched film obtained in the same manner as in Example 1 was adjusted to obtain a polyester base material having retardation = 2800 nm, film thickness = 34 μm, and (nx−ny) = 0.083.
An optical laminate according to Comparative Example 10 was produced in the same manner as Example 1 except that the obtained polyester substrate was used.

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.

(Nijimura evaluation)
The optical laminated body produced in the Example and the comparative example was arrange | positioned on the polarizing element by the side of the observer of a liquid crystal monitor (FLATORON IPS226V (made by LG Electronics Japan)), and the liquid crystal display device was produced. In addition, it arrange | positioned so that the angle which the slow axis of a polyester base material and the absorption axis of the polarizing element by the side of the observer of a liquid crystal monitor may make would be 45 degrees.
In the dark and bright places (illuminance around the LCD monitor 400 lux), the display image is observed visually and through polarized sunglasses from the front and oblique directions (about 50 degrees), and the presence or absence of nidimra is evaluated according to the following criteria. did. Observation through polarized sunglasses is a much stricter evaluation method than visual observation. The observation is performed by 10 people, and the largest number of evaluations are the observation results.
◎: Nizimura is not observed ○: Nizimura is observed, but there is no problem in practical use △: Nizimura is observed thinly ×: Nizimura is observed strongly

(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)).

(All haze)
Based on JIS K7136, the total haze of the obtained optical laminate was measured using a haze meter HM-150 (manufactured 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.
○: Whiteness was not observed.
X: Whiteness was observed.

From Table 1, the optical laminated body which concerns on an Example was a favorable result by all evaluation.
On the other hand, the optical laminates according to Comparative Examples 1 and 5 could not prevent interference fringes because the average inclination angle of the hard coat layer or the low refractive index layer surface was too small.
In the optical laminates according to Comparative Examples 2 to 4 and 6 to 8, one or both of the average inclination angle and the skewness were too large, and the cloudiness was inferior. The optical layered bodies according to Comparative Examples 9 and 10 had a small retardation of the light-transmitting substrate, and were inferior to any Nijira evaluation in either a bright place or a dark place.

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 (14)

An optical laminate having an optical functional layer having a concavo-convex shape on the surface, on one surface of a light-transmitting substrate having a birefringence in the plane,
The light-transmitting substrate having a birefringence in the plane has a retardation of 3000 nm or more,
The optical functional layer is characterized in that the uneven shape on the surface of the optical functional layer has an absolute value of Sk and θa satisfying the following formula where the average inclination angle of the uneven portion is θa and the skewness of the unevenness is Sk. body.
0.01 ° ≦ θa ≦ 0.10 °
| Sk | ≦ 0.5 The light-transmitting substrate having a birefringence in the plane has a refractive index (nx) in the slow axis direction, which is a direction in which the refractive index is large, and a fast axis direction, which is a direction orthogonal to the slow axis direction. The optical laminate according to claim 1, wherein a difference (nx−ny) from a refractive index (ny) is 0.05 to 0.20. 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. The optical laminate according to claim 5, wherein the hard coat layer contains inorganic oxide fine particles and a binder resin. The optical laminate according to claim 7, wherein the inorganic oxide fine particles are hydrophobized inorganic oxide fine particles. The optical laminate according to claim 7 or 8, wherein the inorganic oxide fine particles form aggregates and are contained in the hard coat layer, and the average particle diameter of the aggregates is 100 nm to 2.0 µm. 10. The optical laminate according to claim 1, wherein the light transmissive substrate having a birefringence in the plane is a polyester substrate. The optical laminated body according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, wherein the total haze based on JIS K7136 is less than 2.0. A polarizing plate comprising a polarizing element,
The polarizing plate comprises the optical layered body according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11 on the surface of a polarizing element. An image display device comprising the optical laminate according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11, or the polarizing plate according to claim 12. The image display apparatus of Claim 13 provided with a white light emitting diode as a backlight light source.

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