JP6064406B2 - Optical laminate, polarizing plate, and image display device - Google Patents

Description

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

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 polarizing element is disposed on the image display surface side of the liquid crystal cell, and it is usually required to give hardness so that the polarizing element 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.

From the problems of such cellulose ester film, it is excellent in transparency, heat resistance and mechanical strength, and is cheaper than cellulose ester film and easily available in the market, or can be produced by a simple method. It is desired to use a versatile film as a light-transmitting substrate of an optical laminate. For example, an attempt has been made to use a polyester film such as polyethylene terephthalate as a cellulose ester substitute film (for example, Patent Document 1). To 3).

However, the polyester film has an aromatic ring with a high polarizability in the molecular chain, so the intrinsic birefringence is extremely large, and the molecular chain is oriented by stretching to give excellent transparency, heat resistance, and mechanical strength. Along with this, birefringence is easily developed. When an optical laminate using a light-transmitting substrate having a birefringence in the surface such as a polyester film is installed on the surface of an image display device, the antireflection performance on the surface of the optical laminate is remarkably high. In some cases, the contrast of the bright room was lowered.
In addition, when such a polyester film is disposed on a polarizing element, unevenness of different colors (hereinafter also referred to as “Nijimura”) occurs in the liquid crystal display device, particularly when the display screen is observed from an oblique direction. There is also a problem that the display quality of the display is impaired.

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 4 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 4, the polyester film is biaxially stretched 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 4, the Nijira 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.

Further, for example, Patent Document 5 describes an antiglare film using a polyethylene terephthalate film that is sufficiently transparent by stretching 2.5 to 6 times as a light-transmitting substrate. In this anti-glare film, if the retardation is 1000 or more, the coloration at the front becomes inconspicuous, but the color unevenness in the oblique direction cannot be eliminated, so the total haze is 8 times the transmitted sharpness. Nijimura has been eliminated by making the above. However, since visibility will fall if a permeation | transmission clarity is low, the anti-glare film of patent document 5 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 6, a white light emitting diode is used as a light source, and an angle formed 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 6, 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 6, 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 6, 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 6, the problem of image quality degradation due to the occurrence of interference fringes cannot be avoided.

JP 2004-205773 A JP 2009-157343 A JP 2010-244059 A JP 2008-003541 A JP 2009-156938 A JP2011-107198A

When the present inventors examined the problem in the case of using a light-transmitting substrate made of such a polyester film, as a light-transmitting substrate of the optical laminate, a large in-plane birefringence was obtained. It has been found that the use of a light-transmitting base material having the above can improve the problem of Nizimura as compared with the case of using an optical laminate including a light-transmitting base material made of a conventional polyester film or the like.

However, when such a light-transmitting substrate having a large birefringence in the surface is used and an optical laminate having a hard coat layer provided on the light-transmitting substrate, an optical laminate having such a configuration is used. In the body, the light-transmitting substrate generally has a high refractive index of 1.64 to 1.68, while ensuring the adhesion between the hard coat layer and the light-transmitting substrate and the hard coat layer. The refractive index of the primer layer is low unless the refractive index is increased by any material, and the refractive index difference between the light-transmitting substrate, the primer layer and the hard coat layer is large, resulting in rainbow-like interference fringes. However, there is a problem that the image quality of the display and the like deteriorates.

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 the present invention, in view of the above situation, in a liquid crystal display device using a light-transmitting substrate having a birefringence index in a plane, it is possible to highly suppress the occurrence of nitrite and interference fringes in a display image, It is an object of the present invention to provide an optical laminate and a polarizing plate capable of obtaining an image display device excellent in antireflection performance and bright place contrast, and an image display device provided with the optical laminate or polarizing plate.

The present invention is an image display device comprising 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, The laminated body is disposed on the surface of the image display device, and the concavo-convex shape of the surface of the optical functional layer has an absolute value of Sk when the average inclination angle of the concavo-convex part is θa and the skewness of the concavo-convex part is Sk. And θa satisfy the following formula, and the slow axis, which is the direction in which the refractive index of the light transmissive substrate is large, is arranged in parallel with the vertical direction of the display screen of the image display device, and the light transmissive property The base material has a difference (nx−) between the refractive index (nx) in the slow axis direction, which is a direction in which the refractive index is large, and the refractive index (ny) in the fast axis direction, which is a direction orthogonal to the slow axis direction. ny) is 0.05 or more.
The above-mentioned "the slow axis that is the direction in which the refractive index of the light transmissive substrate is large is arranged in parallel with the vertical direction of the display screen of the image display device" means that the slow axis is the above It means a state in which the optical laminate is arranged on the image display device in a range of less than ± 45 ° with respect to the vertical direction of the display screen. In addition, the “vertical direction of the display screen of the image display device” means the vertical direction of the display screen when the image display device is installed so that the display screen is perpendicular to the floor surface, that is, the display This means the direction perpendicular to the floor of the screen.
0.010 ° ≦ θa ≦ 0.100 °
| Sk | ≦ 0.50

The present invention is an image display device comprising 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, The laminated body is disposed on the surface of the image display device, and the concavo-convex shape of the surface of the optical functional layer has an absolute value of Sk when the average inclination angle of the concavo-convex part is θa and the skewness of the concavo-convex part is Sk. And θa satisfy the following formula, and the slow axis, which is the direction in which the refractive index of the light transmissive substrate is large, is arranged in parallel with the vertical direction of the display screen of the image display device, and the light transmissive property The substrate is also an image display device characterized in that in-plane retardation is 3000 nm or more.
The above-mentioned "the slow axis that is the direction in which the refractive index of the light transmissive substrate is large is arranged in parallel with the vertical direction of the display screen of the image display device" means that the slow axis is the above It means a state in which the optical laminate is arranged on the image display device in a range of less than ± 45 ° with respect to the vertical direction of the display screen. In addition, the “vertical direction of the display screen of the image display device” means the vertical direction of the display screen when the image display device is installed so that the display screen is perpendicular to the floor surface, that is, the display This means the direction perpendicular to the floor of the screen.
0.010 ° ≦ θa ≦ 0.100 °
| Sk | ≦ 0.50
The light transmissive substrate is preferably a polyester substrate.
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
In the present invention, the uneven shape of the optical functional layer preferably has an average wavelength λa represented by λa = 2π × (Ra / tan (θa)) satisfying the following formula.
200 μm ≦ λa ≦ 800 μm
In the present invention, the optical functional layer is preferably a hard coat layer.
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 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.
In addition, the optical laminate of the present invention preferably has a total haze based on JIS K-7136 of less than 2.0%.

The present invention also provides a polarizing plate in which an optical laminate having an optical functional layer having a concavo-convex shape on the surface is provided on a polarizing element on one surface of a light-transmitting substrate having a birefringence index in the plane. The surface roughness of the optical functional layer is such that the average inclination angle of the concavo-convex part is θa and the skewness of the concavo-convex part is Sk, and the absolute value of Sk and θa are as follows: The optical laminate and the polarizing element satisfy the equation, and the slow axis that is the direction in which the refractive index of the light-transmitting substrate is large and the absorption axis of the polarizing element are arranged perpendicular to each other. 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, which is a direction orthogonal to the slow axis direction. The difference (nx−ny) from the refractive index (ny) in the direction is 0.05 or more. It is also an image display device.
The above-mentioned "the slow axis that is the direction in which the refractive index of the light transmissive substrate is large is arranged in parallel with the vertical direction of the display screen of the image display device" means that the slow axis is the above It means a state in which the optical laminate is arranged on the image display device in a range of less than ± 45 ° with respect to the vertical direction of the display screen. In addition, the “vertical direction of the display screen of the image display device” means the vertical direction of the display screen when the image display device is installed so that the display screen is perpendicular to the floor surface, that is, the display This means the direction perpendicular to the floor of the screen.
0.010 ° ≦ θa ≦ 0.100 °
| Sk | ≦ 0.50
The present invention also provides a polarizing plate in which an optical laminate having an optical functional layer having a concavo-convex shape on the surface is provided on a polarizing element on one surface of a light-transmitting substrate having a birefringence index in the plane. The surface roughness of the optical functional layer is such that the average inclination angle of the concavo-convex part is θa and the skewness of the concavo-convex part is Sk, and the absolute value of Sk and θa are as follows: The optical laminate and the polarizing element satisfy the equation, and the slow axis that is the direction in which the refractive index of the light-transmitting substrate is large and the absorption axis of the polarizing element are arranged perpendicular to each other. The light-transmitting substrate having a birefringence in the plane is also an image display device characterized by having an in-plane retardation of 3000 nm or more.
The above-mentioned "the slow axis that is the direction in which the refractive index of the light transmissive substrate is large is arranged in parallel with the vertical direction of the display screen of the image display device" means that the slow axis is the above It means a state in which the optical laminate is arranged on the image display device in a range of less than ± 45 ° with respect to the vertical direction of the display screen. In addition, the “vertical direction of the display screen of the image display device” means the vertical direction of the display screen when the image display device is installed so that the display screen is perpendicular to the floor surface, that is, the display This means the direction perpendicular to the floor of the screen.
0.010 ° ≦ θa ≦ 0.100 °
| Sk | ≦ 0.50
The image display device of the present invention is preferably a VA mode or IPS mode liquid crystal display device including 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 transmissive substrate, the present inventors have found that a light transmissive material having a birefringence in the surface of a polyester substrate or the like. By setting the birefringence of the base material to a predetermined size, it is possible to suppress the occurrence of nitriles in the displayed image. As a result, it was 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.
Further, in an optical laminate or polarizing plate using a light-transmitting substrate having a birefringence in the plane, the refraction of the light-transmitting substrate is set when the coating agent or the polarizing plate is installed in an image display device. An image display device with excellent antireflection performance and bright room contrast by making the slow axis, which is a direction with a high rate, a specific direction with respect to the absorption axis of the polarizing element or the display screen of the image display device As a result, the present invention has been completed.
In addition, the film which consists of a cellulose ester represented by the triacetyl cellulose conventionally used as an optical laminated body as mentioned above is excellent in optical isotropy, and has almost no phase difference in a surface. For this reason, in the case of the optical laminated body or polarizing plate which used the film which consists of this cellulose ester as a light transmissive base material, it was not necessary to consider the installation direction of this light transmissive base material. That is, the above-described problems of antireflection performance and bright room contrast are caused by using a light-transmitting substrate having a birefringence in the surface as the light-transmitting substrate of the optical laminate.

The present invention has an optical functional layer having an optical functional layer having a concavo-convex shape on the surface on one surface of a light-transmitting substrate having a birefringence index in the plane, and is used by being arranged on the surface of an image display Is the body.
In the optical layered body of the present invention, the slow axis, which is the direction in which the refractive index of the light transmissive substrate is large, is arranged in parallel with the vertical direction of the display screen of the image display device.
Here, since the image display device is normally installed and used indoors, reflection of light reflected from the wall surface or floor surface on the display screen (the surface of the optical laminate) of the image display device is prevented. By doing so, the antireflection performance can be made excellent.
The present inventors pay attention to the fact that most of the light reflected on the wall surface or floor surface and incident on the display screen of the image display device vibrates in the left-right direction of the display screen. In the optical layered body of the present invention, the slow axis, which is the direction in which the refractive index of the light transmissive substrate is large, is arranged in parallel with the vertical direction of the display screen of the image display device. That is, the optical layered body of the present invention is limited to those for use on the surface of the image display device, and the image display device provided with the optical layered body of the present invention has the refractive index of the light-transmitting substrate. The slow axis, which is the direction in which the angle is large, is in a state of being oriented in a direction perpendicular to the vibration direction of the light reflected on the wall surface or floor surface. Thus, the image display device in which the optical laminate is installed so that the direction of the slow axis, which is the direction in which the refractive index of the light-transmitting substrate is large, is a specific direction, has antireflection performance and bright room contrast. It will be excellent.
This is because, in the image display device in which the optical laminate of the present invention is arranged in the above-described specific state, the light-transmitting group with respect to light (S-polarized light) that vibrates in the left-right direction with a large proportion of incidence on the display screen. This is because the direction of the fast axis, which is the direction in which the refractive index of the material is small, becomes parallel, and external light reflection can be reduced.
The reason for this is that, as the refractive index of the base material increases, the reflectance increases, but in the base material having refractive index anisotropy such as the light-transmitting base material in the optical laminate of the present invention, This is because the ratio of the refractive index of the fast axis having a small refractive index is increased as the refractive index of the light-transmitting substrate.
The contrast of the image display device is divided into dark room contrast and bright room contrast. The dark room contrast is calculated as (brightness of white display / brightness of black display), and the bright room contrast is {(brightness of white display). + External light reflection) / (black display luminance + external light reflection)}. In any case of contrast, the influence of the denominator becomes larger and the contrast is lowered. That is, if external light reflection can be reduced, the bright room contrast is improved as a result.
The above-mentioned "the slow axis that is the direction in which the refractive index of the light transmissive substrate is large is arranged in parallel with the vertical direction of the display screen of the image display device" means that the slow axis is the above It means a state in which the optical laminate is arranged on the image display device in a range of less than ± 45 ° with respect to the vertical direction of the display screen. In addition, the “vertical direction of the display screen of the image display device” means the vertical direction of the display screen when the image display device is installed so that the display screen is perpendicular to the floor surface, that is, the display This means the direction perpendicular to the floor of the screen.

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 substrate preferably has a retardation of 3000 nm or more. If the retardation is less than 3000 nm, nitjira may occur in the display image of the liquid crystal display device using the optical laminate 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.
It is preferable that the retardation of the said polyester base material is 5000-25000 nm from a viewpoint of Nizimura prevention property and thin film formation. A more preferable range is 7000 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).
Further, using two polarizing plates, the orientation axis direction (principal axis direction) of the polyester substrate is obtained, and the refractive indexes (nx, ny) of two axes orthogonal to the orientation axis direction are Abbe's refractive indices. It can also be determined by the total (NAR-4T manufactured by Atago Co., Ltd.). Furthermore, the thickness d (nm) of the polyester base material can be measured using an electric micrometer (manufactured by Anritsu). And retardation can also be calculated from the product of the refractive index difference (nx−ny) and the thickness d (nm) of the polyester substrate.
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) can be obtained using the following formula.
The average reflectance (R) of the optical functional layer is obtained by applying the raw material composition on 50 μm PET without easy adhesion treatment, forming a cured film with a thickness of 1 to 3 μm, and on the surface (back surface) on which PET is not applied, In order to prevent back surface reflection, the average reflectance of each cured film can be measured after applying a black vinyl tape having a width larger than the measurement spot area (for example, Yamato vinyl tape NO200-38-21 38 mm width). The refractive index of the polyester base material can be measured after a black vinyl tape is 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) 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 Δn is less than 0.05, the refractive index of the fast axis is large, so the contrast of the image display device described above may not be improved. Moreover, when the Δn is less than 0.05, a sufficient nitrite 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 Δn is smaller than 0.07, the effect of preventing azimuth unevenness when the slow axis is arranged perpendicular 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.

Although it does not specifically limit as a material which comprises the said polyester base material, The linear saturated polyester synthesize | combined from aromatic dibasic acid or its ester-forming derivative, and diol or its ester-forming derivative is mentioned. Specific examples of such polyester include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly (1,4-cyclohexylenedimethylene terephthalate), and polyethylene-2,6-naphthalate.
Moreover, the polyester used for the polyester base material may be a copolymer of the above-mentioned polyester, and the above-mentioned polyester is the main component (for example, 80 mol% or more), and a small proportion (for example, 20 mol% or less) It may be blended with a kind of resin. 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 or the like having a 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. For example, a polyester such as the above-described PET is melted, and an unstretched polyester extruded and formed into a sheet is used at a temperature equal to or higher than the glass transition temperature. And a method of performing heat treatment after transverse stretching.
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 a method for controlling the birefringence of the polyester substrate produced by the above-described method 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. If it is less than 40 μm, tearing, tearing and the like are likely to occur, and the practicality as an industrial material may be significantly reduced. 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.

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.
0.010 ° ≦ θa ≦ 0.100 °
| Sk | ≦ 0.50

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 0.010 °. If it is less than 0.010 °, the inclination is not sufficient and interference fringes cannot be prevented. A more preferred lower limit is 0.030 °, and a still more preferred lower limit is 0.040 °. The upper limit of the average inclination angle θa of the uneven portion is 0.100 °. If it exceeds 0.100 °, 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 0.090 °, and a still more preferred upper limit is 0.080 °.

Further, in the present invention, the absolute value of the unevenness skewness Sk is 0.50 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 0.50 or less, since the asymmetry of the surface unevenness shape is small, the deviation of the inclination angle distribution can be moderately suppressed, and interference fringes can be suitably prevented, and at the same time, cloudiness Can be suppressed. The absolute value of the Sk is more preferably 0.40 or less, and still more preferably 0.20 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 fear that a cloudiness may be seen. If the average wavelength λa exceeds 800 μm, the change in the inclination angle on the uneven surface is reduced, and there is a possibility that interference fringes cannot be prevented suitably. A more preferable lower limit of the average wavelength λa is 300 μm, and a more preferable upper limit is 600 μm.

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

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 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. The thickness of the hard coat layer can be measured by observation with a cross-sectional microscope, or can be simply measured with a contact-type thickness meter.

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, polyester resins, polyether resins, acrylic resins, epoxy resins, urethane resins, alkyds having a relatively low molecular weight (number average molecular weight of 300 to 80,000, preferably 400 to 5000) having an unsaturated double bond. Resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, and the like can also be used as the ionizing radiation curable resin. The resin in this case includes all dimers, oligomers, and polymers other than monomers.
Preferred compounds in the present invention include compounds having 3 or more unsaturated bonds. When such a compound is used, the crosslink density of the hard coat layer to be formed can be increased, and the coating hardness can be improved.
Specifically, in the present invention, pentaerythritol triacrylate, pentaerythritol tetraacrylate, polyester polyfunctional acrylate oligomer (3 to 15 functional), urethane polyfunctional acrylate oligomer (3 to 15 functional) and the like are used in appropriate combination. Is preferred.

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 more 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 Resins, silicon resins, polysiloxane resins, etc.

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.

The hard coat layer composition may contain a solvent.
As said solvent, it can select and use according to the kind and solubility of the resin component to be used, for example, ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, diacetone alcohol etc.), ethers ( Dioxane, tetrahydrofuran, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, 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.), water, alcohols (ethanol, isopropanol, butanol, cyclohexanol, etc.), cellosolves (methyl cello) Lube, ethyl cellosolve), cellosolve acetates, sulfoxides (dimethyl sulfoxide), amides (dimethylformamide, dimethylacetamide, etc.) and the like can be exemplified, it may be a mixed solvent thereof.
In particular, in the present invention, it is preferable that at least one of methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, or a mixture thereof is included in the ketone solvent because of excellent compatibility with the resin and coating properties.

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 ionizing radiation curable 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. It is preferable to use it. When the ionizing radiation curable resin is a resin system having a cationic polymerizable functional group, the photopolymerization initiator may be an aromatic diazonium salt, aromatic sulfonium salt, aromatic iodonium salt, metallocene compound, benzoin sulfone. It is preferable to use acid esters alone or as a mixture.
As the initiator used in the present invention, in the case of an ionizing radiation curable resin having a radically polymerizable unsaturated group, 1-hydroxy-cyclohexyl-phenyl-ketone is compatible with the ionizing radiation curable resin, and yellow This is preferable because of little change.

The content of the photopolymerization initiator in the hard coat layer composition is preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the ionizing radiation curable resin. If it is less than 0.5 part by mass, the hardness of the hard coat layer in the optical laminate of the first invention may not be in the above-described range. If it exceeds 10 parts by mass, This is because the ionizing radiation does not reach the deep part and internal hardening is not promoted, and the target pencil hardness of 3H or higher may not be obtained.
The minimum with more preferable content of the said photoinitiator is 2 mass parts, and a more preferable upper limit is 8 mass parts. When the content of the photopolymerization initiator is in this range, a hardness distribution does not occur in the film thickness direction, and uniform hardness is likely to occur.

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.

By containing an antistatic agent in the hard coat layer composition, antistatic performance can be imparted to the hard coat layer.
As the antistatic agent, conventionally known ones can be used. For example, a cationic antistatic agent such as a quaternary ammonium salt, fine particles such as tin-doped indium oxide (ITO), a conductive polymer, or the like can be used. Can do.
When using the said antistatic agent, it is preferable that the content is 1-30 mass% with respect to the total mass of all the solid content.

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) containing 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 Copolymers and the like. Silicone-containing vinylidene fluoride copolymers obtained by adding a silicone component to these copolymers can also be used. The silicone components in this case include (poly) dimethylsiloxane, (poly) diethylsiloxane, (poly) diphenylsiloxane, (poly) methylphenylsiloxane, alkyl-modified (poly) dimethylsiloxane, azo group-containing (poly) dimethylsiloxane, Dimethyl silicone, phenylmethyl silicone, alkyl / aralkyl modified silicone, fluorosilicone, polyether modified silicone, fatty acid ester modified silicone, methyl hydrogen silicone, silanol group containing silicone, alkoxy group containing silicone, phenol group containing silicone, methacryl modified silicone, acrylic Modified silicone, amino modified silicone, carboxylic acid modified silicone, carbinol modified silicone, epoxy modified silicone, mercapto modified silicone Over emissions, fluorine-modified silicones, polyether-modified silicone and the like. Of these, those having a dimethylsiloxane structure are preferred.

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

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

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

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

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

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

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

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

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

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

When the optical functional layer is a hard coat layer, the optical layered body of the present invention 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 polarizing plate of the present invention is a polarizing plate in which an optical functional layer having a concavo-convex shape on a surface is provided on a polarizing element on one surface of a light-transmitting substrate having a birefringence index in the plane. The optical functional layer and the polarizing element are arranged so that the slow axis, which is the direction in which the refractive index of the light-transmitting substrate is large, and the absorption axis of the polarizing element are perpendicular to each other.

As said optical laminated body in the polarizing plate of this invention, the thing similar to the optical laminated body of this invention is mentioned.
In the polarizing plate of the present invention, the light-transmitting substrate having a birefringence index in the plane preferably has a retardation of 3000 nm or more for the same reason as the optical laminate of the present invention described above, and has a refractive index. The difference (nx−ny) between the refractive index (nx) in the slow axis direction, which is the larger direction, and the refractive index (ny) in the fast axis direction, which is the direction perpendicular to the slow axis direction, is 0.05. The above is preferable.

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.

In the polarizing plate of the present invention, the light-transmitting substrate has a slow axis that is a direction in which the refractive index is large and an absorption axis of the polarizing element arranged vertically. Thus, the slow axis which is a direction with a large refractive index of the said light-transmissive base material is arrange | positioned perpendicularly | vertically with respect to the absorption axis of the said polarizing element, and installs the polarizing plate of this invention. As described above, the image display device is excellent in antireflection performance and bright place contrast.
The above-mentioned “the light-transmitting substrate has a slow axis in which the refractive index is large and the absorption axis of the polarizing element are arranged perpendicularly” means that the slow axis is the polarized light. This means a state in which the element is disposed in a range exceeding ± 45 ° with respect to the absorption axis of the element.

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 above optical laminate or polarizing plate, the light source of the light source device is irradiated from below the optical laminate or polarizing plate. 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 backlight light source in the liquid crystal display device is not particularly limited, but is preferably a white light emitting diode (white LED). The image display device is preferably a VA mode or IPS mode liquid crystal display device including a white light emitting diode as a backlight light source.
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. In particular, 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, so they have anti-reflection performance. In addition, it is effective for improving the contrast of a bright place and is excellent in luminous efficiency, so that it is suitable as 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 VA (Vertical Alignment) mode refers to a dark display in which liquid crystal molecules are aligned so as to be perpendicular to the substrate of the liquid crystal cell when no voltage is applied, and the liquid crystal molecules are collapsed when a voltage is applied. This is an operation mode showing bright display.
The IPS (In-Plane Switching) mode is a method in which display is performed by rotating the liquid crystal within the substrate surface by a horizontal electric field applied to a pair of comb electrodes provided on one substrate of the liquid crystal cell. is there.
The image display device using the optical laminate or polarizing plate of the present invention is preferably in the VA mode or IPS mode including a white light emitting diode as a backlight light source for the following reason.
That is, the image display device of the present invention can reduce the reflection of the light (S-polarized light) that vibrates in the left-right direction with a large proportion of incidence on the display screen on the optical laminate or polarizing plate of the present invention. As a result, a lot of S-polarized light is transmitted. Normally, these transmitted S-polarized light is absorbed inside the display device, but there is very little light returning to the observer side. In the VA mode or the IPS mode, since the absorption axis of the polarizer installed on the observer side of the liquid crystal cell is in the horizontal direction, the S-polarized light transmitted through the optical laminate or the polarizing plate of the present invention can be absorbed. This is because the light returning to the observer side can be further reduced.

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. Even when a light-transmitting substrate having a birefringence in the plane such as a polyester film is used, an image display device excellent in antireflection performance and bright place contrast can be obtained. be able to.
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. It is a graph which shows the backlight light source spectrum of the liquid crystal monitor used in Example 11 grade | etc.,.

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.
As the refractive index of the polyester base material, the orientation axis direction of the polyester base material is obtained using two polarizing plates, and the refractive indexes (nx, ny) of two axes orthogonal to the orientation axis direction are expressed as Abbe. It was determined by a refractometer (NAR-4T manufactured by Atago Co., Ltd.). Here, an axis showing a larger refractive index is defined as a slow axis. The thickness d (nm) of the polyester base material was measured using an electric micrometer (manufactured by Anritsu), and the unit was converted to nm. Retardation was calculated | required from the product of the refractive index difference (nx-ny) and the thickness d (nm) of the polyester base material.

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 Gosei Kagaku) 40 parts by mass Irgacure 184 (manufactured by BASF Japan) 5 parts by mass polyether-modified silicone (TSF4460, manufactured by Momentive Performance Materials) 0.025 parts by mass Toluene 105 parts by mass Isopropyl alcohol 30 parts by mass Cyclohexanone 15 parts by mass Fumed silica is a silane compound having an octyl group (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 Gosei Kagaku) 40 parts by mass Irgacure 184 (manufactured by BASF Japan) 5 parts by mass polyether-modified silicone (TSF4460, manufactured by Momentive Performance Materials) 0.025 parts by mass Toluene 105 parts by mass Isopropyl alcohol 30 parts by mass Cyclohexanone 15 parts by mass Fumed silica is a silane compound having an octyl group (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 = 4400 nm, film thickness = 80 μm, and (nx−ny) = 0.055. 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.

(Reference Example 1)
Optical lamination according to Reference Example 1 in the same manner as in Example 1 except that PET film A4100 manufactured by Toyobo Co., Ltd. having retardation = 2500 nm, film thickness = 75 μm, and (nx−ny) = 0.033 was used as the polyester substrate. The body was made.

The optical laminates according to the obtained Examples, Comparative Examples, and Reference Examples were evaluated for the following items.
All the results are shown in Table 1.

(Nijimura evaluation)
The optical laminates produced in Examples, Comparative Examples, and Reference Examples were placed on the observer-side polarizing element of a liquid crystal monitor (FLATRON IPS226V (manufactured by LG Electronics Japan)) to produce a liquid crystal display device. In the optical layered body, the S-polarized light and the fast axis of the polyester base material are parallel, and the angle formed by the slow axis of the polyester base material and the absorption axis of the polarizing element on the observer side of the liquid crystal monitor is 90. It arranged so that it might become °.
Then, in the dark room and bright room (liquid crystal monitor peripheral illumination 400 lux), the display image was observed visually and through the polarized sunglasses from the front and oblique directions (about 50 degrees), and the presence or absence of nidimra was evaluated according to the following criteria. . 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)
Black acrylic for preventing reflection on the back surface (light-transmitting substrate surface) of each optical laminate obtained in Examples, Comparative Examples and Reference Examples through a transparent adhesive. It stuck on the board, the sodium lamp was irradiated to each optical laminated body from the surface of the hard-coat layer or the low-refractive-index layer, it observed visually, and the presence or absence of generation | occurrence | production of an interference fringe was evaluated with the following references | standards.
A: No interference fringes were generated.
○: Some interference fringes were generated, but there was no problem.
X: Interference fringes were generated.

(Cloudiness)
In the dark room, the surface (light transmissive substrate surface) opposite to the hard coat layer of each optical laminate obtained in Examples, Comparative Examples and Reference Examples was attached to a black acrylic plate via a transparent adhesive. The cloudiness was observed under a table lamp (3-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 body according to Reference Example 1 had a small Δn (difference in refractive index between the slow axis and the fast axis) and retardation of the light-transmitting substrate, and was inferior to Nizimura evaluation.

(Example 11, Comparative Example 9)
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 stretching ratio of 1.5 times in the direction of degree to obtain a light-transmitting substrate having nx = 1.70, ny = 1.60, film thickness of 80 μm, and retardation = 8000 nm.
An optical laminate was produced in the same manner as in Example 1 except that the obtained light-transmitting substrate was used, and the relationship between the S-polarized light at the time of reflectance measurement and the fast axis of the optical laminate was the same. An optical laminate is installed on the polarizing element on the viewer side of the liquid crystal monitor (FLATORON IPS226V (manufactured by LG Electronics Japan)) so that the optical functional layer is on the viewer side, and the ambient illuminance is 400 lux. In (light place), the bright room contrast of the display screen was visually evaluated.
In the case of Example 11, the S-polarized light that vibrates in the left-right direction with respect to the display screen having a high incidence on the display screen is parallel to the fast axis of the optical laminate (the slow axis of the optical laminate is the display screen) In the case of Comparative Example 9, the S-polarized light and the slow axis of the optical laminate were installed in parallel, and as a result of evaluation, Example 11 was more than Comparative Example 9. The bright room contrast was excellent, and there was no Nijimura. Comparative Example 9 was inferior in bright room contrast as compared with Example 11 although no Nizimura was observed.
FIG. 2 shows a backlight light source spectrum of the liquid crystal monitor used.

(Example 12, Comparative Example 10)
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 stretching ratio of 1.8 times in the direction of degree to obtain a light-transmitting substrate having nx = 1.68, ny = 1.62, film thickness of 80 μm, and retardation = 4800 nm.
An optical laminate was obtained in the same manner as in Example 1 except that the obtained light-transmitting substrate was used. Using the obtained optical layered body, in Example 12, measurement was performed with the fast axes of the S-polarized light and the antiglare film set in parallel, and in Comparative Example 10, the slow phase of the S-polarized light and the antiglare film was measured. The evaluation was performed with the shaft installed in parallel.
The bright room contrast of Example 12 evaluated in the same manner as in Example 11 was better than that of Comparative Example 10, and there was no Nijimura. On the other hand, in Comparative Example 10, no Nizimura was observed, but the bright room contrast was inferior to that of Example 12.

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 image display device comprising 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 optical laminated body is disposed on the surface of the image display device,
The uneven shape on the surface of the optical functional layer is such that when the average inclination angle of the uneven portion is θa, and the skewness of the uneven portion is Sk, the absolute value of the Sk and θa satisfy the following formula:
The slow axis, which is the direction in which the refractive index of the light transmissive substrate is large, is arranged in parallel with the vertical direction of the display screen of the image display device,
The light-transmitting substrate has a refractive index (nx) in the slow axis direction, which is a direction in which the refractive index is large, and a refractive index (ny) in the fast axis direction, which is a direction orthogonal to the slow axis direction. The difference (nx−ny) is 0.05 or more
An image display device characterized by that.
Note that, “the slow axis that is the direction in which the refractive index of the light-transmitting substrate is large is arranged in parallel with the vertical direction of the display screen of the image display device” means that the slow axis is the above It means a state in which the optical laminate is arranged on the image display device in a range of less than ± 45 ° with respect to the vertical direction of the display screen. Further, the “vertical direction of the display screen of the image display device” means the vertical direction of the display screen when the image display device is installed so that the display screen is perpendicular to the floor surface, that is, the display This means the direction perpendicular to the floor of the screen.
  0.010 ° ≦ θa ≦ 0.100 °
  | Sk | ≦ 0.50 An image display device comprising 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 optical laminated body is disposed on the surface of the image display device,
The uneven shape on the surface of the optical functional layer is such that when the average inclination angle of the uneven portion is θa, and the skewness of the uneven portion is Sk, the absolute value of the Sk and θa satisfy the following formula:
The slow axis, which is the direction in which the refractive index of the light transmissive substrate is large, is arranged in parallel with the vertical direction of the display screen of the image display device,
The light transmissive substrate has an in-plane retardation of 3000 nm or more.
An image display device characterized by that.
Note that, “the slow axis that is the direction in which the refractive index of the light-transmitting substrate is large is arranged in parallel with the vertical direction of the display screen of the image display device” means that the slow axis is the above It means a state in which the optical laminate is arranged on the image display device in a range of less than ± 45 ° with respect to the vertical direction of the display screen. Further, the “vertical direction of the display screen of the image display device” means the vertical direction of the display screen when the image display device is installed so that the display screen is perpendicular to the floor surface, that is, the display This means the direction perpendicular to the floor of the screen.
  0.010 ° ≦ θa ≦ 0.100 °
  | Sk | ≦ 0.50 Light transmitting substrate, an image display apparatus according to claim 1 or 2, wherein the polyester substrate. 4. The image display device 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 5. The image display device according to claim 4 , wherein the uneven shape of the optical functional layer is such that an average wavelength λa represented by λa = 2π × (Ra / tan (θa)) satisfies the following formula.
200 μm ≦ λa ≦ 800 μm The optical functional layer, the image display apparatus according to claim 1, 2, 3, 4 or 5, wherein the hard coat layer. The optical functional layer, the image display apparatus according to claim 1, 2, 3, 4, or 5, wherein the low refractive index layer on the hard coat layer is layered on the barrier. The hard coat layer, an image display apparatus according to claim 6 or 7 containing an inorganic oxide fine particles and a binder resin. The image display device according to claim 8 , wherein the inorganic oxide fine particles are hydrophobized inorganic oxide fine particles. Inorganic oxide fine particles is contained in the hard coat layer to form an aggregate, the image display apparatus according to claim 8 or 9, wherein an average particle diameter of the aggregates is 100Nm～2.0Myuemu.
In addition, the average particle diameter of the aggregate of the inorganic oxide fine particles is selected from a 5 μm square region containing a large amount of aggregates of the inorganic oxide fine particles based on 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 image display device according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, wherein the total haze based on JIS K-7136 is less than 2.0%. An image display comprising an optical laminate having an optical functional layer having an uneven surface on one surface of a light-transmitting substrate having a birefringence index in a plane, and a polarizing plate provided on a polarizing element A device,
The uneven shape on the surface of the optical functional layer is such that when the average inclination angle of the uneven portion is θa, and the skewness of the uneven portion is Sk, the absolute value of the Sk and θa satisfy the following formula:
The optical layered body and the polarizing element are arranged such that a slow axis that is a direction in which a refractive index of the light-transmitting substrate is large and an absorption axis of the polarizing element are perpendicular to each other.
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 difference (nx−ny) from the refractive index (ny) is 0.05 or more.
An image display device characterized by that.
Note that, “the slow axis that is the direction in which the refractive index of the light-transmitting substrate is large is arranged in parallel with the vertical direction of the display screen of the image display device” means that the slow axis is the above It means a state in which the optical laminate is arranged on the image display device in a range of less than ± 45 ° with respect to the vertical direction of the display screen. Further, the “vertical direction of the display screen of the image display device” means the vertical direction of the display screen when the image display device is installed so that the display screen is perpendicular to the floor surface, that is, the display This means the direction perpendicular to the floor of the screen.
  0.010 ° ≦ θa ≦ 0.100 °
  | Sk | ≦ 0.50 An image display comprising an optical laminate having an optical functional layer having an uneven surface on one surface of a light-transmitting substrate having a birefringence index in a plane, and a polarizing plate provided on a polarizing element A device,
The uneven shape on the surface of the optical functional layer is such that when the average inclination angle of the uneven portion is θa, and the skewness of the uneven portion is Sk, the absolute value of the Sk and θa satisfy the following formula:
The optical layered body and the polarizing element are arranged such that a slow axis that is a direction in which a refractive index of the light-transmitting substrate is large and an absorption axis of the polarizing element are perpendicular to each other.
The light-transmitting substrate having a birefringence in the plane has an in-plane retardation of 3000 nm or more.
An image display device characterized by that.
Note that, “the slow axis that is the direction in which the refractive index of the light-transmitting substrate is large is arranged in parallel with the vertical direction of the display screen of the image display device” means that the slow axis is the above It means a state in which the optical laminate is arranged on the image display device in a range of less than ± 45 ° with respect to the vertical direction of the display screen. Further, the “vertical direction of the display screen of the image display device” means the vertical direction of the display screen when the image display device is installed so that the display screen is perpendicular to the floor surface, that is, the display This means the direction perpendicular to the floor of the screen.
  0.010 ° ≦ θa ≦ 0.100 °
  | Sk | ≦ 0.50 14. A VA mode or IPS mode liquid crystal display device having a white light emitting diode as a backlight source. 14. The liquid crystal display device of claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 , Image display device.

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