JP2003270409A - Light diffusing film, antireflection film, polarizing plate and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a wide viewing field angle of an image display device, particularly to prevent gradation inversion in the downward direction of the panel of a liquid crystal display device and reflection of external light, and to obtain an image without an out-of-focus state even in a high-definition liquid crystal display device. <P>SOLUTION: In the light diffusing film having a transparent base material and a light diffusing layer, the light diffusing layer is controlled in such a manner that the intensity of scattered light at 30° is 0.01 to 0.2% of the intensity of light at 0° exit angle in the profile of scattered light by a goniophotometer. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a light diffusion film having a transparent substrate and a light diffusion layer. The present invention also relates to an antireflection film having a transparent substrate, a light diffusion layer and a low refractive index layer in this order. Furthermore, the present invention also relates to a polarizing plate in which protective films are provided on both sides of the polarizing film. Furthermore, the present invention also relates to an image display device using a light diffusion film, an antireflection film or a polarizing plate.

[0002]

2. Description of the Related Art Generally, a liquid crystal display device comprises a polarizing plate and a liquid crystal cell. The display quality defects of the liquid crystal display device are the viewing angle and the reflection of external light. Regarding the viewing angle, in the currently mainstream TN mode TFT liquid crystal display device, JP-A-8-50206 and JP-A-7-191.
A liquid crystal display device having an extremely wide viewing angle is realized by inserting an optical compensation film between a polarizing plate and a liquid crystal cell as described in Japanese Patent No. 217 and European Patent No. 0911656A2. However, the liquid crystal display device still has a problem that gray scale inversion occurs in the lower direction of the panel. To solve this problem, a light diffusing means is disclosed in Japanese Patent No. 2822983, an optical axis conversion plate is disclosed in JP 2001-33783 A, and an optical means for diffusing outgoing light is disclosed in JP 2001-56461 A. It has been proposed that the display quality is remarkably improved by providing the display surface on the viewing side. However, the specific means described in these is a light diffusing means having a highly controlled lens structure or a diffractive structure, which is expensive and very difficult to mass-produce.

Japanese Patent Laid-Open Nos. 6-18706 and 10-201
No. 03 discloses a light diffusion film which is inexpensive and can be mass-produced, which is formed by applying a resin containing a filler (eg, silicon dioxide (silica)) on the surface of a transparent base film. There is. JP-A-11-160505 and 1
1-305010, 11-326608, JP-A-2
000-121809, 2000-180611
No. 2000-338310,
Other light diffusing films are disclosed. Even if these light diffusion films were used, the improvement in display quality was insufficient. In recent years, liquid crystal display devices are often used for high-definition monitors with fine pixels. When the light diffusing film is used in a high-definition monitor, another big problem is that the image is easily blurred.

On the other hand, an antireflection film is generally used for the reflection of external light. Anti-reflection film,
In order to prevent deterioration of contrast and reflection of an image due to reflection of external light, it is arranged on the outermost surface of the display which reduces the reflectance by using the principle of optical interference. However,
The conventional antireflection film cannot solve the above-mentioned problem of the viewing angle, and there is a demand for an antireflection film that is excellent in the reflection of external light and that can solve the problem of the viewing angle.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to achieve a wide viewing angle of a liquid crystal display device, in particular, to realize gradation reversal in the lower direction of the panel and prevention of external light reflection.
It is also an object of the present invention to realize a clear image even in a high-definition liquid crystal display device. Further, an object of the present invention is also to expand the viewing angle (particularly the downward viewing angle) without increasing the thickness of the liquid crystal panel. Still another object of the present invention is to prevent the occurrence of contrast deterioration, gradation or black / white inversion, or hue change due to a change in viewing angle.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a light diffusion film (1) to (5) below, and (6) and (7) below.
Anti-reflection film, polarizing plate of the following (8) to (10),
And the image display device described in (11) and (12) below. (1) A light diffusing film having a transparent substrate and a light diffusing layer, wherein the light diffusing layer has a light emission angle of 0 ° in the scattered light profile of the goniometer in the range of 0.01 to 0.2%. A light diffusion film having a scattered light intensity of 30 ° with respect to the intensity.

(2) The light diffusion layer has a scattered light intensity of 60 ° with respect to a light intensity of an emission angle of 0 ° of the scattered light profile of the goniometer in the range of 0.02% or less. Light diffusion film. (3) The light diffusion film according to (1), wherein the light diffusion layer has a total haze value in the range of 40 to 90%. (4) The light diffusion film according to (1), wherein the light diffusion layer has an internal diffusion haze value in the range of 30 to 80%. (5) The light diffusion film according to (1), wherein the light diffusion layer is made of a light-transmitting resin and light-transmitting fine particles, and the light-transmitting fine particles have a refractive index different from that of the light-transmitting resin.

(6) An antireflection film having a transparent substrate, a light diffusing layer and a low refractive index layer in this order, wherein the light diffusing layer is in the range of 0.01 to 0.2%. The scattered light intensity of the scattered light profile of the meter is 30 ° with respect to the light intensity of 0 °, and the antireflection film has a specular reflectance of 450 to 650 nm at an incident angle of 5 ° in the range of 2.5% or less. An antireflection film having an average value in the wavelength region. (7) The antireflection film as described in (6), wherein the light diffusion layer has a scattered light intensity of 60 ° with respect to a light intensity of an emission angle of 0 ° of the scattered light profile of the goniometer in the range of 0.02% or less. .

(8) A polarizing plate in which protective films are provided on both sides of a polarizing film, one of the protective films being the light diffusion film described in (1) to (5) or (6) or (7). A polarizing plate, which is the antireflection film as described in 1. (9) An optical anisotropic layer composed of the light diffusion film described in (1) to (5) or the antireflection film described in (6) or (7), a polarizing film and a liquid crystalline compound in this order. Polarizer. (10) The polarizing plate according to (9), wherein the liquid crystalline compound is a discotic compound. (11) The light diffusion film described in (1) to (5),
An image display device comprising the antireflection film according to (6) or (7) or the polarizing plate according to (8) to (10) as an outermost layer of a display. (12) Image display device is TN mode, VA mode, OC
The image display device according to (11), which is a B-mode, IPS-mode, or ECB-mode liquid crystal display device.

[0010]

The present inventor has found that there is a correlation between the intensity distribution of scattered light measured by a goniophotometer and the effect of improving the viewing angle. The present inventor has conducted further research, and by controlling the haze value and using an antireflection film in which a specific low refractive index layer is laminated, the reflection of external light and the viewing angle can be achieved without sacrificing the blurring of the image. Achieved improvement. That is, the more the light emitted from the backlight is diffused by the light diffusing film provided on the surface of the polarizing plate on the viewing side, the better the viewing angle characteristic becomes. However, if it is diffused too much, the backscatter becomes large and the front luminance is reduced. Further, if the scattering is too large, there arises a problem that the image clarity is deteriorated.
Therefore, it is necessary to control the scattered light intensity distribution within a certain range.

As a result of further study by the present inventor, in order to achieve a desired visual recognition characteristic, the emission angle of the scattered light profile is 0.
Correlation with a viewing angle improvement effect for a light intensity of 3 °
It was found that the scattered light intensity of 0 ° should be controlled within a certain range. From the viewpoint of image clarity, it has also been found that it is sufficient to control the scattered light intensity in the 60 ° direction, which is correlated with the blurring of the image. As a result, according to the present invention, it is possible to achieve a wide viewing angle of the liquid crystal display device, in particular, a gradation inversion in the lower direction of the panel and a prevention of reflection of external light. Further, according to the present invention, a high-definition liquid crystal display device can also realize a clear image. Further, according to the present invention, the viewing angle (particularly the downward viewing angle) can be expanded without increasing the thickness of the liquid crystal panel. Furthermore, according to the present invention, it is possible to prevent a decrease in contrast, inversion of gradation or black and white, or a change in hue due to a change in viewing angle.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, in order to achieve a desired visual recognition characteristic, a scattered light intensity of 30 °, which correlates with a viewing angle improving effect, with respect to a light intensity of an outgoing angle of 0 ° of a scattered light profile. Is adjusted to a range of 0.01 to 0.2%. Three
The scattered light intensity at 0 ° is preferably in the range of 0.02 to 0.15%, more preferably in the range of 0.03 to 0.1%. From the viewpoint of image clarity, it is more preferable to control the scattered light intensity in the 60 ° direction that correlates with blurring of the image. Specifically, the scattered light intensity at 60 ° with respect to the light intensity at the exit angle of 0 ° of the scattered light profile is preferably 0.02% or less, and 0.0
It is more preferably 1% or less, and most preferably 0.005% or less. The scattered light profile is
The prepared light-scattering film can be measured using a commercially available automatic goniophotometer (GP-5 type, manufactured by Murakami Color Research Laboratory Co., Ltd.).

Adjustment of the haze value is also important for improving the viewing angle characteristics. 30% to 80% as internal scattering haze
Is preferred, 35% to 70% is more preferred, and 40%
To 60% is the most preferable. As a method of increasing the internal scattering haze, there are methods such as increasing the concentration of particles having a particle diameter of 0.5 to 2.0 μm, increasing the film thickness, and further increasing the refractive index of the particles. In addition to the internal scattering haze, it is also necessary to provide the surface haze with the surface irregularities from the viewpoint of visibility. Corner improvement effect is exhibited, 40% to 9
0% is preferable, 45% to 80% is more preferable, 5
Most preferred is 0% to 70%.

[Basic Structure of Light Diffusing Film] FIG. 1 is a schematic sectional view showing the basic structure of the light diffusing film. Figure 1
The light diffusion film (10) shown in (1) is a transparent substrate film (20), a light diffusion layer (30) and a low refractive index layer (50).
And are laminated. The light diffusion layer (30) contains the first transparent particles (41) and the second transparent particles (42) in the transparent resin (31). The light diffusion layer (30) may be composed of a plurality of layers. You may use translucent fine particles of more than one kind.

The transparent resin (31) of the light diffusion layer (30) preferably has a refractive index of 1.51 to 2.00.
The refractive index of the low refractive index layer (50) is preferably 1.35 to 1.45. The refractive index of triacetyl cellulose preferably used as the transparent substrate film (20) is 1.48. By increasing the refractive index of the light diffusion layer, an excellent antireflection effect can be obtained even when the refractive index of the low refractive index layer is in the range of 1.35 to 1.45. If the refractive index of the light diffusing layer is too small, the antireflection effect decreases. When the refractive index of the light diffusion layer is too large, the tint of reflected light becomes strong.

[Light Diffusing Layer] The light diffusing layer is composed of translucent particles and a translucent resin. The scattered light profile and the haze value are adjusted by the transparent particles and the transparent resin. In the present invention,
It is preferable to use translucent fine particles having two or more kinds of particle diameters.

Each of the two or more kinds of transparent fine particles is
It is preferable that the difference in refractive index from the translucent resin forming the entire light diffusion layer is 0.02 to 0.20. If the difference in refractive index is less than 0.02, the difference in refractive index between the two is too small to obtain the light diffusion effect. When the difference in refractive index is larger than 0.20, the light diffusivity is too high and the entire film is whitened. The difference in refractive index is more preferably 0.03 to 0.15, most preferably 0.04 to 0.13. The particle size of the transparent fine particles (42) is 0.5 μm.
To 2.0 μm is preferable. By adjusting the particle diameter, the above-mentioned angular distribution of light scattering can be obtained.

In the present invention, in order to improve the display quality (improve the downward viewing angle), it is necessary to diffuse the incident light to some extent. The greater the diffusion effect, the better the viewing angle characteristics. However, in order to maintain the front brightness in terms of display quality, it is necessary to increase the transmittance as much as possible. When the particle size is 0.5 μm or less, the scattering effect is large and the viewing angle characteristics are dramatically improved, but the backscattering is large and the brightness is drastically reduced. On the other hand, when the thickness is 2.0 μm or more, the scattering effect becomes small and the improvement of the viewing angle characteristic becomes small. Therefore, the particle diameter is preferably 0.6 μm to 1.8 μm, and 0.7 μm
To 1.7 μm is most preferable.

The particle size of the transparent fine particles (41) is preferably 2.5 μm to 5.0 μm. Thereby, the surface scattering suitable for the present invention can be obtained. In order to achieve good display quality, it is also necessary to prevent the reflection of external light. The lower the haze value of the surface, the smaller the blurring of the display, and the clearer the display can be obtained. On the contrary, if it is too high, it becomes whitish (whitening; decrease in black density), and the surface haze value hs is preferably 0.5 <hs <30, more preferably 3 ≦ hs ≦ 20, and 7 ≦ hs ≦ 15.
Is most preferred. In order to control the surface haze value, it is preferable to provide the resin layer surface with appropriate irregularities by using fine particles. Haze value (cloudiness value) is JI
HR-1 manufactured by Murakami Color Research Laboratory according to SK-7105
00 can be used to measure.

When the particle diameter is 2.5 μm or less,
The surface unevenness becomes small, the effect of surface scattering is small, and reflection by external light cannot be sufficiently suppressed. on the other hand,
When it is 5.0 μm or more, the surface irregularities become large,
Although it is possible to suppress the reflection, the display quality will be significantly reduced and the display quality will be degraded. Therefore, the particle diameter is 2.2 μm.
To 4.7 μm are preferred, and 2.4 μm to 4.5 μm
Is most preferred. The surface roughness Ra has a surface roughness Ra of 1.2 μ.
It is preferably m or less, more preferably 0.8 μm or less, and most preferably 0.5 μm or less. Surface roughness is determined by atomic force microscope (AFM).
c Force Microscope, SPI380
Can be measured using 0N, manufactured by Seiko Instruments Inc.

In the translucent fine particles, two or more kinds of translucent fine particles having different particle diameters are used, and the translucent fine particles are mixed so that the viewing angle characteristic relating to the display quality and the reflection of external light can be obtained. Each can be optimized independently, a fine setting can be made according to the mixing ratio of the translucent fine particles, control is possible compared to the case of one type, and various designs are facilitated.

The transparent fine particles (41) and (42)
May be monodisperse organic fine particles or inorganic fine particles. The more uniform the particle size is, the less the scattering characteristics are, and the easier the design of the haze value is. As the transparent fine particles, plastic beads are preferable,
In particular, it is preferable that the transparency is high and the difference in refractive index from the translucent resin is the above-mentioned numerical value. As organic fine particles,
Polymethylmethacrylate beads (refractive index 1.49),
Acrylic-styrene copolymer beads (refractive index 1.5
4), melamine beads (refractive index 1.57), polycarbonate beads (refractive index 1.57), styrene beads (refractive index 1.60), cross-linked polystyrene beads (refractive index 1.
61), polyvinyl chloride beads (refractive index 1.60), benzoguanamine-melamine formaldehyde beads (refractive index 1.68) and the like are used. As inorganic fine particles,
Silica beads (refractive index 1.44), alumina beads (refractive index 1.63) and the like are used.

The particle size of the translucent fine particles is 0.
It is preferable to appropriately select and use a resin having a thickness of 5 to 5 μm, and it is preferable to add 5 to 30 parts by mass with respect to 100 parts by mass of the translucent resin.

In the case of the transparent fine particles as described above, the transparent fine particles easily settle in the resin composition (transparent resin). Therefore, an inorganic filler such as silica is added to prevent settling. May be. As the amount of the inorganic filler added increases, it is more effective in preventing the translucent fine particles from settling, but it adversely affects the transparency of the coating film. Therefore, the particle size is preferably 0.5 μm.
The following inorganic fillers may be contained in an amount of less than 0.1% by mass with respect to the translucent resin so as not to impair the transparency of the coating film.

The translucent resin is a resin which is cured mainly by ultraviolet rays or electron beams, that is, an ionizing radiation curable resin, a mixture of an ionizing radiation curable resin with a thermoplastic resin and a solvent, and a thermosetting resin. Kind is used. The thickness of the light diffusion layer is usually about 0.5 μm to 50 μm, preferably 1 μm to 20 μm, more preferably 2 μm to
The thickness is preferably 10 μm, most preferably 3 μm to 7 μm. The refractive index of the translucent resin is preferably 1.51 to 2.
00, more preferably 1.51 to 1.90, still more preferably 1.51 to 1.85, and particularly preferably 1.51 to 1.80. The refractive index of the transparent resin is a value measured without the transparent fine particles. If the refractive index is too small, the antireflection property will decrease. Further, if it is too large, the tint of reflected light becomes strong, which is not preferable.

The binder used for the translucent resin is preferably a polymer having a saturated hydrocarbon or polyether as the main chain, and more preferably a polymer having a saturated hydrocarbon as the main chain. Further, the binder is preferably crosslinked. The polymer having a saturated hydrocarbon as a main chain is preferably obtained by a polymerization reaction of an ethylenically unsaturated monomer. In order to obtain a crosslinked binder, it is preferable to use a monomer having two or more ethylenically unsaturated groups.

Examples of the monomer having two or more ethylenically unsaturated groups include esters of polyhydric alcohol and (meth) acrylic acid (eg, ethylene glycol di (meth) acrylate, 1,4-dichlorohexanediene). Acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (Meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,3,5-
Cyclohexanetriol trimethacrylate, polyurethane polyacrylate, polyester polyacrylate), vinylbenzene derivatives (eg, 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1,4-divinylcyclohexanone), vinyl sulfone (Eg, divinyl sulfone), acrylamide (eg, methylenebisacrylamide) and methacrylamide. At least 3 of these
An acrylate or methacrylate monomer having one functional group, and further an acrylate monomer having at least five functional groups are preferable from the viewpoint of film hardness, that is, scratch resistance. A mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate is commercially available, and particularly preferably used.

These monomers having an ethylenically unsaturated group can be hardened by a polymerization reaction by ionizing radiation or heat after being dissolved, coated and dried in a solvent together with various polymerization initiators and other additives.

Instead of or in addition to the monomer having two or more ethylenically unsaturated groups, a crosslinked structure may be introduced into the binder by a reaction of a crosslinkable group. Examples of the crosslinkable functional group include an isocyanate group, an epoxy group, an aziridine group, an oxazoline group, an aldehyde group, a carbonyl group, a hydrazine group, a carboxyl group, a methylol group and an active methylene group. Vinyl sulfonic acid, acid anhydride, cyanoacrylate derivative, melamine, etherified methylol, ester and urethane, and metal alkoxide such as tetramethoxysilane can also be used as a monomer for introducing a crosslinked structure. You may use the functional group which shows crosslinkability as a result of a decomposition reaction like a block isocyanate group. That is, in the present invention, the crosslinkable functional group does not immediately show a reaction,
It may exhibit reactivity as a result of decomposition. The binder having these crosslinkable functional groups can form a crosslinked structure by heating after coating.

The transparent resin is preferably formed of a monomer having a high refractive index and / or ultrafine metal oxide particles having a high refractive index, in addition to the binder polymer. Examples of high refractive index monomers include bis (4
-Methacryloylthiophenyl) sulfide, vinylnaphthalene, vinylphenyl sulfide, 4-methacryloxyphenyl-4'-methoxyphenyl thioether and the like. Examples of the metal oxide ultrafine particles having a high refractive index include particles having a particle size of 100 nm or less, preferably 50 nm or less, which is made of at least one oxide selected from zirconium, titanium, aluminum, indium, zinc, tin and antimony. It is preferable to contain fine particles. As the metal oxide ultrafine particles having a high refractive index, Al, Z
Ultrafine oxide particles of at least one metal selected from r, Zn, Ti, In and Sn are preferable, and specific examples thereof include ZrO ₂ , TiO ₂ , Al ₂ O ₃ , In ₂ O ₃ and Zn.
_{O, SnO 2, Sb 2 O} 3, ITO , and the like. Among these, ZrO ₂ is particularly preferably used. The addition amount of the high refractive index monomer and the metal oxide ultrafine particles is preferably 10 to 90% by mass, and more preferably 20 to 80% by mass based on the total mass of the translucent resin.

When the translucent resin and the transparent substrate film are in contact with each other, the solvent of the coating solution for forming the translucent resin has both antiglare property and adhesion between the support and the antiglare layer. To achieve this, the transparent substrate film (for example, triacetyl cellulose support) is composed of at least one kind of solvent and the transparent substrate film is not dissolved. More preferably, at least one of the solvents that does not dissolve the transparent substrate film,
It is preferable that it has a boiling point higher than that of at least one solvent that dissolves the transparent substrate film. More preferably, the solvent having the highest boiling point among the solvents that does not dissolve the transparent substrate film and the solvent having the highest boiling point among the solvents that dissolves the transparent substrate film have a boiling point temperature difference of 30 ° C. or more. Yes, and most preferably 50 ° C. or higher.

The solvent for dissolving the transparent base film (preferably triacetyl cellulose) has a carbon number of 3 to
12 ethers: specifically, dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, 1,4-dioxane, 1,3
-Dioxolane, 1,3,5-trioxane, tetrahydrofuran, anisole, phenetole, and other ketones having 3 to 12 carbon atoms: specifically, acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone , Cyclohexanone, methylcyclohexanone, methylcyclohexanone, etc., having 3 to 12 carbon atoms: Specifically, ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, methyl propionate, propionate ethyl , N-pentyl acetate, and γ-ptyrolactone, and other organic solvents having two or more functional groups: specifically, 2-methoxymethyl acetate, 2-ethoxymethyl acetate, 2-ethoxyethyl acetate, 2-ethoxypropione. Ethyl acid, 2-methoxy Examples thereof include ethanol, 2-propoxyethanol, 2-butoxyethanol, 1,2-diacetoxyacetone, acetylacetone, diacetone alcohol, methyl acetoacetate, and ethyl acetoacetate. These can be used alone or in combination of two or more. As the solvent that dissolves the transparent substrate, a ketone solvent is preferable.

As a solvent which does not dissolve the transparent base film (preferably triacetyl cellulose), methanol,
Ethanol, 1-propanol, 2-propanol, 1
-Butanol, 2-butanol, tert-butanol, 1-pentanol, 2-methyl-2-butanol,
Examples thereof include cyclohexanol, isobutyl acetate, methyl isobutyl ketone, 2-octanone, 2-pentanone, 2-hexanone, 2-heptanone, 3-pentanone, 3-heptanone and 4-heptanone. These can be used alone or in combination of two or more.

The mass ratio (A / B) of the total amount (A) of the solvent that dissolves the transparent substrate film and the total amount (B) of the solvent that does not dissolve the transparent substrate film is 5/95 to 50/50.
Is more preferable, 10/90 to 40/60 is more preferable, and 15/85 to 30/70 is further preferable.

As a method for curing the above-mentioned ionizing radiation-curable resin composition, the above-mentioned ionizing radiation-curable resin composition can be cured by an ordinary curing method, that is, irradiation with an electron beam or an ultraviolet ray.

For example, in the case of electron beam curing, it is emitted from various electron beam accelerators such as Cockroff-Walton type, Van de Graaff type, resonance transformer type, insulating core transformer type, linear type, dynamitron type and high frequency type. 50-1000 KeV,
An electron beam or the like having an energy of 100 to 300 KeV is preferably used, and in the case of ultraviolet curing, ultraviolet rays or the like emitted from light rays such as an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, carbon arc, xenon arc, and a metal halide lamp can be used. .

[Low Refractive Index Layer] The low refractive index layer is provided as an antireflection layer on the outermost layer on the side where the light diffusion layer is provided on the support for the purpose of imparting antireflection ability. The refractive index of the low refractive index layer is preferably 1.35 to 1.45 as described above. The refractive index of the low refractive index layer preferably satisfies the following mathematical formula (I). (Mλ / 4) × 0.7 <n ₁ d ₁ <(mλ / 4) × 1.3 Formula (I) In the formula, m is a positive odd number (generally 1), and n ₁ has low refraction. Is the refractive index of the low refractive index layer, and d ₁ is the film thickness (nm) of the low refractive index layer. Λ is the wavelength of visible light,
The value is in the range of 50 to 650 (nm). Note that satisfying the above mathematical expression (I) means that there is m (a positive odd number, usually 1) that satisfies the mathematical expression (I) in the above wavelength range.

For the low refractive index layer of the present invention, a fluorine-containing resin obtained by curing a thermosetting or ionizing radiation-curable crosslinkable fluorine-containing compound is used. As a result, the scratch resistance is excellent even when used as the outermost layer, as compared with the low refractive index layer using magnesium fluoride or calcium fluoride. The heat-curable or ionizing radiation-curable crosslinkable fluorine-containing compound preferably has a refractive index of 1.35 or more and 1.45 or less. The dynamic friction coefficient of the cured fluororesin is preferably 0.03 to
0.15, the contact angle to water is preferably 90 to 120
It is degree. As such a crosslinkable fluorine-containing compound,
In addition to a perfluoroalkyl group-containing silane compound (for example, (heptadecafluoro-1,1,2,2-tetradecyl) triethoxysilane), a fluorine-containing monomer and a monomer for imparting a crosslinkable group are contained as constituent units. Fluorine copolymers may be mentioned.

Specific examples of the fluorine-containing monomer unit include:
For example, fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole, etc.), a part of (meth) acrylic acid or Completely fluorinated alkyl ester derivatives (eg, biscoat 6F
M (Osaka Organic Chemical) and M-2020 (Daikin)
Etc.), fully or partially fluorinated vinyl ethers and the like.

Examples of the monomer for imparting a crosslinkable group include a (meth) acrylate monomer having a crosslinkable functional group in the molecule such as glycidyl methacrylate, as well as a carboxyl group, a hydroxyl group, an amino group and a sulfonic acid group. Examples thereof include (meth) acrylate monomers (for example, (meth) acrylic acid, methylol (meth) acrylate, hydroxyalkyl (meth) acrylate, allyl acrylate, etc.). The latter is after copolymerization,
It is disclosed in JP-A-10-25388 and JP-A-10-147739 that a crosslinked structure can be introduced.

For the low refractive index layer, not only a copolymer of the above-mentioned fluorine-containing monomer and a monomer for imparting a crosslinkable group, but also a polymer obtained by copolymerizing this with another monomer may be used. Other monomers that may be copolymerized are not particularly limited, and examples thereof include olefins (ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride, etc.), acrylic acid esters (methyl acrylate, methyl acrylate, ethyl acrylate). , 2-ethylhexyl acrylate), methacrylic acid esters (methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate, etc.), styrene derivatives (styrene, divinylbenzene, vinyltoluene, α)
-Methylstyrene etc.), vinyl ethers (methyl vinyl ether etc.), vinyl esters (vinyl acetate, vinyl propionate, vinyl cinnamate etc.), acrylamides (N-tert-butyl acrylamide, N-cyclohexyl acrylamide etc.), methacrylamide Examples thereof include acrylonitrile derivative and the like.

The fluorine-containing resin used for the low refractive index layer preferably has an average particle size of 0.1 μm in order to impart scratch resistance.
m or less, more preferably 0.001 to 0.05 μm S
It is preferable to use ultrafine oxide particles of i. From the viewpoint of antireflection property, the lower the refractive index, the more preferable, but as the refractive index of the fluororesin is lowered, the scratch resistance deteriorates.
Therefore, by optimizing the refractive index of the fluorine-containing resin and the addition amount of the Si oxide ultrafine particles, it is possible to find the best balance between scratch resistance and low refractive index. As the Si oxide ultrafine particles, silica sol dispersed in a commercially available organic solvent may be added to the coating solution as it is, or various commercially available silica powders may be dispersed in an organic solvent and used.

The antireflection film has a vertical peel charge of -200 pc (pico coulomb) / cm ² to + measured with respect to either triacetyl cellulose (TAC) or polyethylene terephthalate (PET) at room temperature and normal humidity.
It is preferably 200 pc (pico coulomb) / cm ² . More preferably -100 pc / cm to +100 p
c / cm ² , and more preferably -50 pc / cm ^2.
To +50 pc / cm ² , most preferably 0 pc /
cm ² . Here, the unit pc (pico coulomb)
Is 10 ⁻¹² coulomb. More preferably, the vertical peeling charge measured at room temperature of 10% RH is −100 pc / c.
m ² to +100 pc / cm ² , and more preferably −
It is 50 pc / cm ² to +50 pc / cm ² , and most preferably 0 pc / cm ² .

The method of measuring the vertical peeling charge is as follows. The measurement sample is left in advance for 2 hours or more under the environment of measurement temperature and humidity. The measuring device is composed of a table on which the sample to be measured is placed and a head which holds the film of the other party and which can repeatedly press and peel from the sample to be measured, and an electrometer for measuring the charge amount is connected to this head. The antiglare antireflection film to be measured is placed on a table, and TAC or PET is attached to the head. After destaticizing the measurement portion, the head is pressed against the measurement sample and peeling is repeated, and the charge values at the first peeling and the fifth peeling are read and averaged. This is repeated for 3 samples with different samples, and the average of all is taken as the vertical peeling charge.

Depending on the type of the companion film or the sample to be measured, it may be positively charged or may be negatively charged, but the problem is the magnitude of the absolute value. Further, generally, the absolute value of charging becomes larger in an environment of low humidity. The absolute value of the antiglare antireflection film of the present invention is also small.

The antireflection film has a normal temperature and a normal humidity and a normal temperature of 1
Since the absolute value of vertical peeling charge at 0% RH is small, it is excellent in dustproofness. To set the value of vertical peel charge within the above range,
It is performed by adjusting the ratio of various elements on the surface of the antireflection film.

The surface resistance value of the antireflection film is 1 × 1.
It is 0 ¹¹ Ω / □ or more, preferably 1 × 10 ¹² Ω / □ or more. The method for measuring the surface resistance value is the circular electrode method described in JIS. That is, the current value one minute after the voltage application is read to obtain the surface resistance value (SR). In the present invention, the concept is fundamentally different from the method of improving the dustproof property (dust adhesion preventing property) by reducing the surface resistance value, for example, 1 × 10 ¹⁰ Ω / □ or less. This method is not used because the image display quality is deteriorated. In the present invention, the absolute value of vertical peeling electrification is made small by the above-mentioned method. Therefore, it is not necessary to make the surface resistance value small, and the surface resistance value is 1 × 10. It can be set to ¹¹ Ω / □ or more and the image display quality does not deteriorate.

In the antireflection film, the average value of the specular reflectance at 5 degrees incidence in the wavelength region from 450 nm to 650 nm is 2.5% or less, preferably 1.2% or less, more preferably 1.1. % Or less. Further, the average value of the integrated reflectance at 5 degrees incidence in the wavelength region from 450 nm to 650 nm is preferably 2.5% or less, more preferably 2.3% or less.

The specular reflectance at 5 ° incidence and the 5 ° incidence will be described. The specular reflectance at 5 ° incidence is the ratio of the intensity of light reflected at −5 ° in the normal direction to the light incident at + 5 ° in the normal direction of the sample, and is a measure of the reflection of the background due to specular reflection. When applied to an anti-glare anti-reflection film, the amount of scattered light resulting from the surface irregularities provided for imparting the anti-glare property is equal to the normal direction −
The intensity of the light reflected at 5 degrees becomes weak. Therefore, it can be said that the specular reflectance is a measurement method that reflects the contributions of both the antiglare property and the antireflection property.

On the other hand, the integrated reflectance at 5 degrees incidence is
It is the ratio of the integrated value of the intensity of light reflected in all directions to the light incident from the sample normal direction +5 degrees. When applied to an antireflection film, since the reflected light does not decrease due to the antiglare property, it is possible to perform a measurement that reflects only the antireflection property. Therefore, both reflectances above 450
The anti-glare property and the anti-reflection property are satisfied at the same time by setting the average values in the wavelength range from nm to 650 nm to 2.5% or less (specular reflectance) and 2.5% or less (integrated reflectance), respectively. It will be possible.

When the average value of the specular reflectance of the antireflection film at 5 degrees incidence in the wavelength region from 450 nm to 650 nm exceeds 2.5%, the reflection of the background becomes a concern, and the surface film of the display device is annoyed. The visibility when applied is reduced. On the other hand, if the average value of the integrated reflectance of the antireflection film at 5 degrees incidence in the wavelength region from 450 nm to 650 nm exceeds 2.5%, the contrast improving effect of the display device is reduced and the antiglare property is imparted. The display screen becomes white due to the scattered light due to the surface irregularities, and the display quality of the display device deteriorates.

The antireflection film is a CIE standard light source D6.
The tint of the specular reflection light with respect to the 5 degree incident light of 5 is CIE19.
When quantified by L *, a *, and b * values in the 76L * a * b * color space, L * ≦ 10, 0 ≦ a * ≦ 2, and −5, respectively.
It is preferably designed to fall within the range of ≦ b * ≦ 2. The tint of regular reflection light that satisfies this is a neutral tint. The tint of the specular reflection light with respect to the 5 degree incident light of the CIE standard light source D65 is 380n at the 5 degree incident wavelength.
From the spectral reflection spectrum obtained by calculating the product of the measured value of the specular reflectance in the region from m to 780 nm and the spectral distribution at each wavelength of the light source D65, CIE1976L * a
It can be quantified by calculating the L * value, the a * value, and the b * value in the * b * color space. When the L * value is larger than 10, the antireflection property is not sufficient. If the a * value is larger than 2, the reddish purple color of the reflected light is strong, and if it is less than 0, the green color is strong, which is not preferable. Further, when the b * value is less than -5, the bluish tint is strong, and when it is more than 2, the yellowish tint is strong, which is not preferable.

The antireflection film having such a neutral color reflected light and a low reflectance optimizes the balance between the refractive index of the low refractive index layer and the refractive index of the binder material of the antiglare layer. It is obtained by doing. In general, an antireflection film composed of three or more layers of optical thin film formed by vapor deposition, sputtering or the like can reduce the average value of the specular reflectance to 0.3% or less, and thus the L * value to 3 or less. Was 10 or more and the b * value was less than -10, and the tint of the reflected light was very strong. However, in the antiglare antireflection film of the present invention, in terms of the tint of the reflected light. Has been greatly improved.

[Transparent Substrate] Materials for the transparent substrate include a transparent resin film, a transparent resin plate, a transparent resin sheet and transparent glass. As the transparent resin film, triacetyl cellulose (TAC) film (refractive index 1.48), polyethylene terephthalate (PET) film, diacetylene cellulose film, acetate butyrate cellulose film, polyether sulfone film, polyacrylic resin film Polyurethane resin film, polyester film, polycarbonate film, polysulfone film, polyether film, polymethylpentene film, polyetherketone film, (meth) acrylonitrile film, etc. can be used. The thickness is usually about 25 μm to 1000 μm. Since the transparent substrate is used on the outermost surface of the polarizing plate, it is preferable to use a cellulose acetate film which is generally used as a protective film for the polarizing plate. As the transparent substrate film of the light-scattering film, a cellulose acetate film having high transparency and a smooth surface is preferable.

In the present invention, it is particularly preferable to use cellulose acetate having a degree of acetylation of 59.0 to 61.5% for the transparent substrate film. The degree of acetylation means the amount of bound acetic acid per unit mass of cellulose. Acetification degree is A
According to the measurement and calculation of the degree of acetylation in STM: D-817-91 (testing method for cellulose acetate, etc.). The viscosity average degree of polymerization (DP) of cellulose ester is
It is preferably 250 or more, more preferably 290 or more. Further, the cellulose ester used in the present invention preferably has a narrow molecular weight distribution of Mw / Mn (Mw is a mass average molecular weight and Mn is a number average molecular weight) by gel permeation chromatography. The specific value of Mw / Mn is preferably 1.0 to 1.7, more preferably 1.3 to 1.65, and most preferably 1.4 to 1.6. preferable.

Generally, cellulose acylate of 2, 3,
The 6-hydroxyl group is not evenly distributed in 1/3 of the entire substitution degree, and the 6-hydroxyl group substitution degree tends to be small. In the present invention, it is preferable that the substitution degree of the 6-position hydroxyl group of cellulose acylate is higher than that of the 2- and 3-position.
The hydroxyl group at the 6-position is preferably substituted by 32% or more with an acyl group, more preferably 33% or more, and particularly preferably 34% or more with respect to the entire substitution degree. Further, the substitution degree of the 6-position acyl group of cellulose acylate is preferably 0.88 or more. The 6-position hydroxyl group may be substituted with an acyl group having 3 or more carbon atoms, such as a propionyl group, a butyroyl group, a valeroyl group, a benzoyl group, and an acryloyl group, in addition to the acetyl group. The substitution degree at each position can be measured by NMR. As the cellulose acylate of the present invention, "0043" to "0044", "Example" [Synthesis Example 1], "0048" to "0049" [Synthesis Example 2] and "0" described in JP-A No. 11-5851.
The cellulose acetate obtained by the method of "051" to "0052" [Synthesis example 3] can be used.

It is preferable to produce the cellulose acetate film by the solvent casting method. In the solvent cast method, a film is manufactured using a solution (dope) in which cellulose acetate is dissolved in an organic solvent.
The organic solvent includes ether having 3 to 12 carbon atoms, ketone having 3 to 12 carbon atoms, and 3 to 12 carbon atoms.
It is preferable to include a solvent selected from the ester and a halogenated hydrocarbon having 1 to 6 carbon atoms. The ether, ketone and ester may have a cyclic structure. A compound having two or more functional groups of ether, ketone and ester (that is, -O-, -CO- and -COO-) can also be used as the organic solvent. The organic solvent may have another functional group such as an alcoholic hydroxyl group. In the case of an organic solvent having two or more kinds of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.

Examples of ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole. Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone. Examples of the ester having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate.

Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol. The number of carbon atoms in the halogenated hydrocarbon is preferably 1 or 2, and most preferably 1. The halogen of the halogenated hydrocarbon is preferably chlorine.
The proportion of hydrogen atoms in the halogenated hydrocarbon substituted with halogen is preferably 25 to 75 mol%, more preferably 30 to 70 mol%, and 3
It is more preferably 5 to 65 mol%, and most preferably 40 to 60 mol%. Methylene chloride is a typical halogenated hydrocarbon. You may mix and use 2 or more types of organic solvents.

The cellulose acetate solution can be prepared by a general method. The general method means treatment at a temperature of 0 ° C. or higher (normal temperature or high temperature). The solution can be prepared by using the dope preparation method and apparatus in the usual solvent casting method. In the case of a general method, it is preferable to use a halogenated hydrocarbon (particularly methylene chloride) as the organic solvent. A non-chlorine-based solvent can also be used, and examples thereof include those described in Published Technical Report 2001-1745. The amount of cellulose acetate is adjusted so that the obtained solution contains 10 to 40% by mass. The amount of cellulose acetate is more preferably 10 to 30% by mass. The organic solvent (main solvent) may contain any of the additives described below. The solution is
It can be prepared by stirring cellulose acetate and an organic solvent at room temperature (0 to 40 ° C.). The highly concentrated solution may be stirred under pressure and heat.
Specifically, the cellulose acetate and the organic solvent are placed in a pressure vessel and sealed, and the mixture is stirred under pressure while being heated to a temperature not lower than the boiling point of the solvent at room temperature and not boiling the solvent. The heating temperature is usually 40 ° C. or higher, preferably 60 to 200 ° C., and more preferably 80.
To 110 ° C.

Each component may be roughly mixed in advance and then put in a container. Moreover, you may throw in in a container one by one. The container must be configured to allow stirring. The container can be pressurized by injecting an inert gas such as nitrogen gas. Alternatively, the increase in vapor pressure of the solvent due to heating may be used.
Alternatively, after sealing the container, each component may be added under pressure. When heating, it is preferable to heat from the outside of the container. For example, a jacket type heating device can be used. It is also possible to heat the entire container by providing a plate heater outside the container and piping to circulate the liquid. It is preferable to provide a stirring blade inside the container and use this to stir. The stirring blade is preferably long enough to reach the vicinity of the wall of the container. A scraping blade is preferably provided at the end of the stirring blade in order to renew the liquid film on the wall of the container. Instruments such as a pressure gauge and a thermometer may be installed in the container. Each component is dissolved in a solvent in a container.
The prepared dope is cooled and then taken out from the container, or after taking out, it is cooled using a heat exchanger or the like.

The solution can also be prepared by the cooling dissolution method. In the cooling dissolution method, cellulose acetate can be dissolved even in an organic solvent which is difficult to dissolve by a usual dissolution method. Even if the solvent is a solvent that can dissolve cellulose acetate by an ordinary dissolution method, the cooling dissolution method has an effect of rapidly obtaining a uniform solution. In the cooling dissolution method, first, cellulose acetate is gradually added to an organic solvent with stirring at room temperature. The amount of cellulose acetate is preferably adjusted so as to be contained in this mixture in an amount of 10 to 40% by mass. The amount of cellulose acetate is more preferably 10 to 30% by mass. Furthermore, any additives described below may be added to the mixture.

Next, the mixture is heated to -100 to -10 ° C (preferably -80 to -10 ° C, more preferably -50).
To -20 ° C, most preferably -50 to -30 ° C). The cooling can be carried out, for example, in a dry ice / methanol bath (-75 ° C) or a cooled diethylene glycol solution (-30 to -20 ° C). When cooled in this way, the mixture of cellulose acetate and organic solvent solidifies. The cooling rate is preferably 4 ° C./min or more, more preferably 8 ° C./min or more, 12
Most preferably, it is at least ° C / min. The higher the cooling rate, the more preferable, but 10000 ° C./sec is the theoretical upper limit, 1000 ° C./sec is the technical upper limit, and 1
00 ° C./sec is a practical upper limit. The cooling rate is
The difference between the temperature at the start of cooling and the final cooling temperature is
It is the value divided by the time from the start of cooling until the final cooling temperature is reached.

Further, this is 0 to 200 ° C. (preferably 0 to 150 ° C., more preferably 0 to 120 ° C.,
When heated to the most preferably 0 to 50 ° C., the cellulose acetate dissolves in the organic solvent. The temperature may be raised by leaving it at room temperature or by heating it in a warm bath. The heating rate is preferably 4 ° C / min or more, and 8 ° C / min.
It is more preferably at least minutes, and most preferably at 12 ° C./minute or more. The higher the heating rate, the more preferable, but 10000 ° C./sec is the theoretical upper limit,
0 ° C./sec is the technical upper limit and 100 ° C./sec is the practical upper limit. The heating rate is a value obtained by dividing the difference between the temperature at the start of heating and the final heating temperature by the time from the start of heating until the final heating temperature is reached. . A uniform solution is obtained as described above. If the dissolution is insufficient, the cooling and heating operations may be repeated. Whether or not the dissolution is sufficient can be judged only by visually observing the appearance of the solution.

In the cooling dissolution method, it is desirable to use a closed container in order to avoid mixing of water due to dew condensation during cooling. In the cooling and heating operation, pressure is applied during cooling,
If the pressure is reduced during heating, the dissolution time can be shortened. In order to carry out the pressurization and depressurization, it is desirable to use a pressure resistant container. A 20% by mass solution of cellulose acetate (acetylation degree: 60.9%, viscosity average degree of polymerization: 299) dissolved in methyl acetate by a cooling dissolution method was 3% by differential scanning calorimetry (DSC).
A quasi-phase transition point between a sol state and a gel state exists near 3 ° C., and at this temperature or lower, a uniform gel state is obtained. Therefore,
This solution must be kept at a temperature not lower than the pseudo phase transition temperature, preferably about 10 ° C. plus the gel phase transition temperature. However, this pseudo-phase transition temperature differs depending on the degree of acetylation of cellulose acetate, the viscosity average degree of polymerization, the solution concentration and the organic solvent used.

A cellulose acetate film is produced from the prepared cellulose acetate solution (dope) by the solvent casting method. The dope is cast on a drum or band and the solvent is evaporated to form a film. The dope before casting is preferably adjusted in concentration so that the solid content is 18 to 35%. The surface of the drum or band is preferably mirror-finished. Regarding the casting and drying methods in the solvent casting method, US Pat.
No. 03, No. 2492078, No. 2492977, No. 2492978, No. 2607704, No. 27390.
No. 69, No. 2739070, British Patent 640731.
Nos. 736,892 and JP-B-45-455
4, JP-A-49-5614, JP-A-60-176834.
Nos. 60-203430 and 62-115035. The dope is preferably cast on a drum or band having a surface temperature of 10 ° C. or lower.
After casting, it is preferable to apply air for 2 seconds or more to dry. It is also possible to strip the obtained film from the drum or band and further dry it with hot air whose temperature is successively changed from 100 to 160 ° C. to evaporate the residual solvent. The above method is described in Japanese Patent Publication No. 5-17844. According to this method, the time from casting to stripping can be shortened. In order to carry out this method, it is necessary for the dope to gel at the surface temperature of the drum or band during casting.

The prepared cellulose acylate solution (dope) can be used to form a film by casting two or more layers. In this case, it is preferable to produce the cellulose acylate film by the solvent casting method. The dope is cast on a drum or band and the solvent is evaporated to form a film. The concentration of the dope before casting is preferably adjusted so that the solid content is 10 to 40%. The surface of the drum or band is preferably mirror-finished.

In the case of casting a plurality of cellulose acylate liquids of two or more layers, it is possible to cast a plurality of cellulose acylate solutions, and a plurality of castings provided at intervals in the traveling direction of the support. The film may be prepared by casting a solution containing cellulose acylate from the mouth and laminating the solutions, and for example, JP-A-61-158414, JP-A-1-122419, and JP-A-11-198285,
The method described in etc. can be applied. Further, it may be formed into a film by casting a cellulose acylate solution from two casting ports, for example, JP-B-60-27.
562, JP-A-61-94724, JP-A-61-9
47245, JP 61-104813 A, JP 6
It can be carried out by the method described in JP-A-1-158413 and JP-A-6-134933. Also, JP-A-56-16261
A cellulose acylate film casting method in which the flow of the high-viscosity cellulose acylate solution described in No. 7 is wrapped with a low-viscosity cellulose acylate solution and the high- and low-viscosity cellulose acylate solutions are simultaneously extruded may be used.

Alternatively, by using two casting ports, the film formed on the support by the first casting port is peeled off, and the second casting is performed on the side in contact with the surface of the support. , A film may be prepared, for example, Japanese Patent Publication No.
4-20235. The cellulose acylate solution to be cast may be the same solution,
Different cellulose acylate solutions may be used and are not particularly limited. In order to impart a function to a plurality of cellulose acylate layers, a cellulose acylate solution corresponding to the function may be extruded from each casting port. Further, the cellulose acylate solution is used for other functional layers (for example, an adhesive layer,
A dye layer, an antistatic layer, an antihalation layer, a UV absorbing layer, a polarizing layer, etc.) can be simultaneously cast.

In the case of the monolayer solution, it is necessary to extrude a high-concentration and high-viscosity cellulose acylate solution in order to obtain a required film thickness, in which case the stability of the cellulose acylate solution is poor and the cellulose acylate solution is solid. This often causes problems, such as the generation of objects, defective spots, and poor flatness. As a solution to this problem, by casting a plurality of cellulose acylate solutions through a casting port, it is possible to simultaneously extrude a highly viscous solution onto a support, thereby improving the flatness and producing an excellent planar film. Not only that, but also by using a concentrated cellulose acylate solution, the reduction of the drying load can be achieved, and the film production speed can be increased.

A plasticizer may be added to the cellulose acetate film in order to improve the mechanical properties or the drying speed. As a plasticizer,
Phosphate esters or carboxylic acid esters are used. Examples of phosphate esters include triphenyl phosphate (TPP) and tricresyl phosphate (TC).
P) is included. Typical carboxylic acid esters are phthalic acid esters and citric acid esters. Examples of phthalates include dimethyl phthalate (DM
P), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethyl hexyl phthalate (DEHP). An example of a citric acid ester is triethyl O-acetylcitrate (OACT).
E) and tributyl O-acetylcitrate (OACT
B) is included. Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate,
Includes dibutyl sebacate and various trimellitic acid esters. Phthalates plasticizer (DMP, DE
P, DBP, DOP, DPP, DEHP) are preferably used. DEP and DPP are particularly preferred. The amount of plasticizer added is 0.1 to 25 times the amount of cellulose ester.
It is preferably mass%, more preferably 1 to 20 mass%, and most preferably 3 to 15 mass%.

A deterioration inhibitor (eg, antioxidant, peroxide decomposer, radical inhibitor, metal deactivator, acid scavenger, amine) may be added to the cellulose acetate film. For the deterioration preventing agent, see JP-A-3-19920.
No. 1, No. 5-1907073, No. 5-194789
Nos. 5,271,471 and 6,107,854. The addition amount of the deterioration inhibitor is preferably 0.01 to 1% by mass of the solution (dope) to be prepared, and more preferably 0.01 to 0.2% by mass. If the addition amount is less than 0.01% by mass, the effect of the deterioration inhibitor is hardly recognized. Addition amount is 1% by mass
If it exceeds the range, bleed-out (bleeding) of the deterioration preventive agent on the film surface may be observed. Butylated hydroxytoluene (BHT) and tribenzylamine (TBA) can be mentioned as examples of particularly preferable deterioration preventing agents.

The cellulose acetate film is preferably surface-treated. Specific methods include corona discharge treatment, glow discharge treatment, flame treatment, acid treatment, alkali treatment and ultraviolet irradiation treatment. It is also preferable to provide an undercoat layer as described in JP-A-7-333433. From the viewpoint of maintaining the flatness of the film, the temperature of the cellulose acetate film in these treatments is Tg or less, specifically 150
It is preferable that the temperature is not higher than ° C. When used as a transparent protective film for a polarizing plate, it is particularly preferable to carry out acid treatment or alkali treatment, that is, saponification treatment of cellulose acetate, from the viewpoint of adhesion to the polarizing film. The surface energy is preferably 55 mN / m or more,
It is more preferably 60 mN / m or more and 75 mN / m or less.

Hereinafter, the alkali saponification treatment will be specifically described as an example. After immersing the film surface in an alkaline solution,
It is preferable to carry out a cycle of neutralizing with an acidic solution, washing with water and drying. Examples of the alkaline solution include potassium hydroxide solution and sodium hydroxide solution, and the normal concentration of hydroxide ion is preferably 0.1N to 3.0N, more preferably 0.5N to 2.0N. preferable. The temperature of the alkaline solution is preferably room temperature to 90 ° C, more preferably 40 ° C to 70 ° C. From the viewpoint of productivity, it is preferable to apply an alkaline solution, and after the saponification treatment, remove the alkali from the film surface by washing with water. From the viewpoint of wettability, alcohols such as IPA, n-butanol, methanol and ethanol are preferable as the coating solvent, and it is preferable to add water, propylene glycol, ethylene glycol and the like as an alkali dissolution aid. The surface energy of a solid can be determined by the contact angle method, the heat of wetting method, and the adsorption method as described in "Wet Basics and Applications" (published by Realize 1989.12.10). In the case of the cellulose acetate film of the present invention, it is preferable to use the contact angle method. Specifically, two kinds of solutions having known surface energies are dropped onto a cellulose acetate film, and at the intersection between the surface of the droplet and the film surface, the angle between the tangent line drawn to the droplet and the film surface is used. The angle containing the drop is defined as the contact angle,
The surface energy of the film can be calculated by calculation.

[Optically Anisotropic Layer Consisting of Liquid Crystal Compound] The liquid crystal compound used in the optically anisotropic layer may be a rod-shaped liquid crystal or a discotic liquid crystal, and they may be a high-molecular liquid crystal or a low-molecular liquid crystal, and further, , Including those in which a low-molecular liquid crystal is crosslinked and no longer exhibits liquid crystallinity. The most preferable liquid crystal compound of the present invention is discotic liquid crystal.

As a preferable example of the rod-shaped liquid crystal, Japanese Patent Application Laid-Open No. 20
Examples thereof include those described in 00-304932.
Examples of the discotic liquid crystal of the present invention include C.I. De
Strade et al., Mol. Cryst. 71
Vol., Page 111 (1981), benzene derivatives, C.I. Report of Destrade et al., Mol.
Cryst. 122, 141 (1985), Ph
ysics lett, A, 78, 82 (199
0)), a truxene derivative described in B. Kohn
e et al., Angew. Chem. Volume 96, 70
Page (1984) and the cyclohexane derivative described in J. M. Lehn et al., J. Chem. Co
mmun. , Pp. 1794 (1985), J. Zhan
g., et al. Am. Chem. Soc. 116
Vol. 2, pp. 2655 (1994), and azacrown-based and phenylacetylene-based macrocycles. Generally, the discotic liquid crystal has a structure in which a linear alkyl group, an alkoxy group, a substituted benzoyloxy group or the like is radially substituted as the linear chain with these as a mother nucleus of the molecular center, and liquid crystallinity is improved. Show. However, it is not limited to the above description as long as the molecule itself has negative uniaxiality and can impart a certain orientation. Further, in the present invention, the formation of a discotic compound does not necessarily mean that the final product is the compound, and for example, the low molecular weight discotic liquid crystal is heated,
Those having a group which reacts with light or the like and consequently polymerized or crosslinked by reaction with heat, light or the like to have a high molecular weight and lose liquid crystallinity are also included. A preferred example of the discotic liquid crystal is described in JP-A-8-50206.

The optically anisotropic layer is a layer having a birefringence composed of a compound having a discotic structural unit, and the discotic structural unit has a plane inclined with respect to the transparent support surface and the discotic structural unit. It is preferable that the angle formed by the surface of (1) and the surface of the transparent support changes in the depth direction of the optically anisotropic layer.

The surface angle (tilt angle) of the discotic structural unit generally increases or decreases in the depth direction of the optically anisotropic layer and as the distance from the bottom surface of the optically anisotropic layer increases. The tilt angle preferably increases with increasing distance. Further, examples of the change in the tilt angle include continuous increase, continuous decrease, intermittent increase, intermittent decrease, change including continuous increase and decrease, and intermittent change including increase and decrease. it can. The intermittent change includes a region where the inclination angle does not change in the middle of the thickness direction. It is preferable that the inclination angle is increased or decreased as a whole even if it includes a region that does not change. Further, it is preferable that the inclination angle is increased as a whole, and it is particularly preferable that the inclination angle is continuously changed.

The above-mentioned optically anisotropic layer is generally prepared by applying a solution prepared by dissolving a discotic compound and another compound in a solvent onto the alignment film, drying it, and then heating it to a discotic nematic phase forming temperature, and then arranging it in the alignment state ( It is obtained by maintaining and cooling the discotic nematic phase). Alternatively, the optically anisotropic layer may be prepared by applying a solution of a discotic compound and another compound (further, for example, a polymerizable monomer or a photopolymerization initiator) dissolved in a solvent onto the alignment film, followed by drying, and then discotic nematic. It is obtained by heating to a phase forming temperature, polymerizing (by irradiation with UV light, etc.), and further cooling. The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline compound used in the present invention is 70 to
300 degreeC is preferable and 70-170 degreeC is especially preferable.

For example, the tilt angle of the discotic unit on the support side can be adjusted by generally selecting the discotic compound or the material of the alignment film, or by selecting the rubbing treatment method. Further, the inclination angle of the discotic unit on the surface side (air side) is generally selected from a discotic compound or another compound (eg, a plasticizer, a surfactant, a polymerizable monomer and a polymer) used together with the discotic compound. It can be adjusted. Further, the degree of change in the tilt angle can be adjusted by the above selection.

The above-mentioned plasticizer, surfactant and polymerizable monomer have compatibility with the discotic compound,
Any compound can be used as long as it can change the tilt angle of the liquid crystal discotic compound or does not hinder the alignment. Of these, polymerizable monomers (eg, compounds having a vinyl group, a vinyloxy group, an acryloyl group and a methacryloyl group) are preferable.
The above compound is generally used in an amount of 1 to 50% by mass (preferably 5 to 30% by mass) based on the discotic compound. Further, examples of preferable polymerizable monomers include polyfunctional acrylates. The number of functional groups is 3
It is preferably functional or higher, and more preferably tetrafunctional or higher. Most preferred are hexafunctional monomers. Preferred examples of the hexafunctional monomer include dipentaerythritol hexaacrylate. It is also possible to mix and use these polyfunctional monomers having different numbers of functional groups.

As the polymer, any polymer can be used as long as it is compatible with the discotic compound and can change the tilt angle of the liquid crystal discotic compound. Cellulose ester can be mentioned as an example of a polymer. Preferred examples of the cellulose ester include cellulose acetate, cellulose acetate propionate, hydroxypropyl cellulose and cellulose acetate butyrate. The polymer is generally 0.1 to 10% by mass (preferably 0.1 to 8% by mass, particularly 0.1 to 5% by mass) relative to the discotic compound so as not to hinder the alignment of the liquid crystalline discotic compound. ) Amount used. In the present invention, the cellulose acetate film, the alignment film provided thereon, and the discotic liquid crystal formed on the alignment film are preferably rubbing-treated films made of a crosslinked polymer.

[Alignment Film] The alignment film is a layer composed of two crosslinked polymers. At least one polymer,
Any polymer that is crosslinkable by itself or that is crosslinked by a crosslinking agent can be used.
The above-mentioned alignment film is formed by reacting a polymer having a functional group or a polymer having a functional group introduced therein with light, heat, a change in PH, etc. between the polymers; It can be formed by introducing a bonding group derived from a cross-linking agent between polymers using an agent and cross-linking between the polymers.

Such cross-linking is usually carried out by applying a coating solution containing the above-mentioned polymer or a mixture of the polymer and the cross-linking agent on a transparent support and then heating the solution. Since it suffices to ensure the durability, the treatment for crosslinking may be carried out at any stage after the alignment film is applied on the transparent support until the final optical compensation sheet is obtained. Considering the orientation of the compound having a discotic structure (optically anisotropic layer) formed on the orientation film, it is also preferable that the compound having the discotic structure is oriented and then sufficiently crosslinked. That is, on the transparent support,
When a coating solution containing a polymer and a cross-linking agent capable of crosslinking the polymer is applied, it is dried by heating (generally, crosslinking is carried out, but when the heating temperature is low, it was heated to the discotic nematic phase formation temperature. (Cross-linking sometimes progresses further), rubbing treatment is performed to form an alignment film,
Then, a coating solution containing a compound having a disc-shaped structural unit is applied onto the alignment film, heated to a discotic nematic phase formation temperature or higher, and then cooled to form an optically anisotropic layer.

The polymer used in the alignment film of the present invention is
Either polymers which are themselves crosslinkable or polymers which are crosslinked by crosslinking agents can be used. Of course, some polymers are capable of both. Examples of the above polymer include polymethylmethacrylate, acrylic acid / methacrylic acid copolymer, styrene / maleinimide copolymer, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylolacrylamide), styrene / vinyltoluene copolymer. , Chlorosulfonated polyethylene,
Polymers such as nitrocellulose, polyvinyl chloride, chlorinated polyolefins, polyesters, polyimides, vinyl acetate / vinyl chloride copolymers, ethylene / vinyl acetate copolymers, carboxymethyl cellulose, polyethylene, polypropylene and polycarbonate, and silane coupling agents, etc. A compound can be mentioned. Examples of preferable polymers are water-soluble polymers such as poly (N-methylol acrylamide), carboxymethyl cellulose, gelatin, polyvinyl alcohol and modified polyvinyl alcohol, and further gelatin, polyvinyl alcohol and modified polyvinyl alcohol are preferable, and especially polyvinyl alcohol is preferable. Bill alcohol and modified polyvinyl alcohol can be mentioned.

Among the above polymers, polyvinyl alcohol or modified polyvinyl alcohol is preferable, and it is most preferable to use two kinds of polyvinyl alcohol or modified polyvinyl alcohol having different polymerization degrees in combination. The polyvinyl alcohol has, for example, a saponification degree of 70 to 100%, and generally has a saponification degree of 80 to 100%.
More preferably, the saponification degree is 85 to 95%. The degree of polymerization is preferably in the range of 100 to 3000.
As the modified polyvinyl alcohol, one modified by copolymerization (as the modifying group, for example, COONa, Si (OX))
₃ , N (CH ₃ ) ₃ · Cl, C ₉ H ₁₉ COO, SO ₃ N
a, C ₁₂ H _25, etc.), those modified by chain transfer (eg, COONa, SH, C
₁₂ H ₂₅ etc.), those modified by block polymerization (eg, COOH, CON
H ₂ , COOR, C ₆ H _{5 and the} like are introduced), and modified products of polyvinyl alcohol. Among these, unmodified or modified polyvinyl alcohol having a saponification degree of 80 to 100%, and more preferably unmodified or alkylthio-modified polyvinyl alcohol having a saponification degree of 85 to 95%. The method of synthesizing these modified polymers, the measurement of visible absorption spectrum, and the method of determining the introduction rate y are described in detail in JP-A-8-338913.

The following may be mentioned as specific examples of the cross-linking agent used together with the above-mentioned polymers such as polyvinyl alcohol. Is also included). For example, activating aldehydes (eg, formaldehyde, glyoxal and glutaraldehyde), N-methylol compounds (eg, dimethylolurea and methyloldimethylhydantoin), dioxane derivatives (eg, 2,3-dihydroxydioxane), and carboxyl groups. Compounds that act by (eg, carbenium, 2-naphthalene sulfonate, 1,1-bispyrrolidino-1-
Chloropyridinium and 1-morpholinocarbonyl-3
-(Sulfonatoaminomethyl)), an active vinyl compound (eg 1,3,5-triacroyl-hexahydro-s)
-Triazine, bis (vinyl sulfone) methane and N,
N′-methylenebis- [β- (vinylsulfonyl) propionamide]), active halogen compound (eg, 2,4-
Dichloro-6-hydroxy-S-triazine), isoxazoles, and dialdehyde starch. These can be used alone or in combination. In view of productivity, it is preferable to use aldehydes having high reaction activity, especially glutaraldehyde.

The cross-linking agent is not particularly limited, and the addition amount tends to improve as the moisture resistance is increased. However, since the alignment ability as an alignment film decreases when 50% by mass or more is added to the polymer,
0.1 to 20 mass% is preferable, and 0.5 to 15 mass% is particularly preferable. The alignment film of the present invention contains some cross-linking agent that has not reacted even after the completion of the cross-linking reaction, but the amount of the cross-linking agent is preferably 1.0% by mass or less in the alignment film. It is particularly preferably 0.5% by mass or less. If the cross-linking agent is contained in the alignment film in an amount exceeding 1.0 mass, sufficient durability cannot be obtained. That is,
When used in a liquid crystal display device, reticulation may occur when it is used for a long period of time or left in a high temperature and high humidity atmosphere for a long period of time.

The alignment film is basically formed by applying it on a transparent support containing the above-mentioned polymer and a cross-linking agent, which is a material for forming the alignment film, followed by heat drying (cross-linking) and rubbing treatment. The crosslinking reaction may be carried out at any time after coating on the transparent support, as described above. When using a water-soluble polymer such as the polyvinyl alcohol as an alignment film forming material, the coating liquid is preferably a mixed solvent of an organic solvent such as methanol and a water having an antifoaming action, and the ratio is mass. Water by ratio:
Methanol is generally 0: 100 to 99: 1,
It is preferably 0: 100 to 91: 9. Thereby, the generation of bubbles is suppressed, and the defects on the alignment film and, further, on the surface of the optically anisotropic layer are significantly reduced. Examples of the coating method include a spin coating method, a dip coating method, a curtain coating method, an extrusion coating method, a bar coating method and an E-type coating method. The E-type coating method is particularly preferable. The film thickness is 0.
It is preferably 1 to 10 μm. Heat drying at 20 ℃ to 11 ℃
It can be carried out at 0 ° C. In order to form sufficient cross-linking, the temperature is preferably 60 ° C to 100 ° C, particularly 80 ° C to 10 ° C.
0 ° C is preferred. The drying time can be 1 minute to 36 hours. It is preferably 5 minutes to 30 minutes. p
H is also preferably set to an optimum value for the cross-linking agent used, and when glutaraldehyde is used, the pH is 4.
5 to 5.5, especially 5 is preferable.

The alignment film is provided on the transparent support or on the undercoat layer. The alignment film can be obtained by crosslinking the polymer layer as described above and then rubbing the surface. The alignment film functions so as to define the alignment direction of the liquid crystal discotic compound provided thereon.

For the rubbing treatment, a treatment method widely adopted as a liquid crystal alignment treatment process for LCD can be used. That is, a method of obtaining orientation by rubbing the surface of the orientation film in a certain direction with paper, gauze, felt, rubber, nylon, polyester fiber or the like can be used. Generally, it is carried out by rubbing several times with a cloth or the like in which fibers having uniform length and thickness are evenly flocked.

[Transparent Support Coated with Optically Anisotropic Layer] The transparent support is not particularly limited as long as it is a plastic film having a high transmittance, but cellulose acetate, which is a protective film of a polarizing plate, is used. preferable. Optically 1
It may be axial or biaxial. Since the transparent support on which the optically anisotropic layer is coated plays an important role in itself, the Re retardation value of the transparent support of the present invention is 0 to 200 nm, and the Rth retardation is The value is preferably adjusted to 70 to 400 nm. When two optically anisotropic cellulose acetate films are used in the liquid crystal display device, the Rth retardation value of the film is preferably 70 to 250 nm. When a single optically anisotropic cellulose acetate film is used in the liquid crystal display device, the Rth retardation value of the film is preferably 150 to 400 nm.

The birefringence (Δn: nx-ny) of the cellulose acetate film is 0.00 to 0.00.
It is preferably 2. The birefringence of the cellulose acetate film in the thickness direction {(nx + ny) / 2-
nz} is preferably 0.001 to 0.04. The retardation value (Re) is calculated according to the following formula. Retardation value (Re) = (nx−ny) × d In the formula, nx is a refractive index in the in-plane slow axis direction of the retardation plate (maximum in-plane refractive index); ny is a retardation It is the refractive index in the direction perpendicular to the slow axis in the plane of the plate. (II) Rth = {(nx + ny) / 2−nz} × d In the formula (II), the refractive index in the slow axis direction (direction in which the refractive index is maximum) in the film plane is shown. ny is the refractive index in the fast axis direction (direction in which the refractive index is minimum) in the film plane. nz is a refractive index in the thickness direction of the film. d
Is the film thickness in nm.

[Polarizing Plate] The polarizing plate comprises a polarizing film and two protective films arranged on both sides of the polarizing film. As one of the protective films, the light diffusion film and antireflection film of the present invention can be used. As the other protective film, a usual cellulose acetate film may be used. The polarizing film includes an iodine-based polarizing film, a dye-based polarizing film using a dichroic dye, and a polyene-based polarizing film. The iodine type polarizing film and the dye type polarizing film are generally manufactured using a polyvinyl alcohol type film. The transparent substrate of the light diffusion film or the slow axis of the cellulose acetate film and the transmission axis of the polarizing film are arranged so as to be substantially parallel to each other. It was found that the moisture permeability of the protective film is important for the productivity of the polarizing plate. The polarizing film and the protective film are attached to each other with an aqueous adhesive, and this adhesive solvent is dried by diffusing in the protective film. The higher the moisture permeability of the protective film, the faster the drying will be and the more the productivity will improve. The polarization ability is reduced.

The moisture permeability of the polarizing plate is determined by the transparent substrate, the thickness of the polymer film (and the polymerizable liquid crystal compound), the free volume,
It is determined by hydrophilicity / hydrophobicity, etc. When the light-diffusing film or antireflection film of the present invention is used as a protective film for a polarizing plate, it has a moisture permeability of 100 to 1000 g / m ² · 24.
It is preferably hrs and is 300 to 700 g / m ²
-It is more preferable that it is 24 hrs. In the case of film formation, the thickness of the transparent substrate can be adjusted by the lip flow rate and line speed, or stretching and compression. Since the moisture permeability differs depending on the main material used, it is possible to adjust the thickness to a preferable range. In the case of film formation, the free volume of the transparent substrate can be adjusted by the drying temperature and time. Also in this case, since the moisture permeability differs depending on the main material used, it is possible to adjust the free volume to a preferable range. The hydrophilicity / hydrophobicity of the transparent substrate can be adjusted by an additive. The moisture permeability can be increased by adding a hydrophilic additive to the free volume, and conversely, the moisture permeability can be decreased by adding a hydrophobic additive. By independently controlling the moisture permeability, it becomes possible to manufacture a polarizing plate having an optical compensation ability at low cost and with high productivity.

In the present invention, a polarizing plate in which the light diffusion film or antireflection film of the present invention, a polarizer and an optically anisotropic layer comprising a liquid crystalline compound are laminated in this order is preferable. The optically anisotropic layer may be formed as a layer containing a discotic compound (discotic compound) or a rod-shaped liquid crystal compound on the polymer film. In the present invention, the liquid crystal compound is preferably a discotic compound. The optically anisotropic layer is preferably formed by orienting a discotic compound (or a rod-shaped liquid crystal compound) and fixing the orientation state. The discotic compound is
It generally has a large birefringence. In addition, the discotic compound has various orientation forms. Therefore, by using the discotic compound, an optically anisotropic layer having optical properties which cannot be obtained by the conventional stretched birefringent film can be obtained. Regarding the optically anisotropic layer using a discotic compound, JP-A-6-214116 and U.S. Pat. No. 5,583,679.
No. 5,646,703, West German Patent Publication 3911620.
There is a description in each specification of A1.

[G-Display Device] The light-diffusing film, antireflection film or polarizing plate of the present invention is advantageously used in an image display device, and is preferably used in the outermost layer of a display. The image display device includes a liquid crystal display device, an organic electroluminescence display device, a plasma display panel and a cathode ray tube display device. It is particularly effective when used in a liquid crystal display device. TN, VA, OCB, IP
The S and ECB mode liquid crystal display devices include a liquid crystal cell and two polarizing plates arranged on both sides of the liquid crystal cell. The liquid crystal cell carries liquid crystal between two electrode substrates. In the liquid crystal display device, one optically anisotropic layer is arranged between the liquid crystal cell and one of the polarizing plates, or two optically anisotropic layers are arranged between the liquid crystal cell and both of the polarizing plates.

The liquid crystal cell has VA mode, OCB mode,
Alternatively, the TN mode is preferable. In a VA mode liquid crystal cell, rod-shaped liquid crystal molecules are aligned substantially vertically when no voltage is applied.

The VA mode liquid crystal cell includes (1) a VA mode liquid crystal cell in a narrow sense in which rod-shaped liquid crystal molecules are aligned substantially vertically when no voltage is applied, and substantially horizontally when a voltage is applied. In addition to (Kaihei 2-176625 gazette), (2) a liquid crystal cell (SID9) in which the VA mode is multi-domain (MVA mode) for widening the viewing angle.
7. Digest of tech. Papers 28 (199)
7) 845), (3) A liquid crystal cell of a mode (n-ASM mode) in which rod-like liquid crystal molecules are substantially vertically aligned when no voltage is applied and twisted in multi-domain alignment when a voltage is applied (preliminary report of the Japan Liquid Crystal Conference). Vol 58-59 (1998)
Description) and (4) SURVAIVAL mode liquid crystal cell (announced at LCD International 98).

The OCB mode liquid crystal cell is a liquid crystal display device using a bend alignment mode liquid crystal cell in which rod-shaped liquid crystal molecules are aligned in substantially opposite directions (symmetrically) in the upper part and the lower part of the liquid crystal cell. No. 4,583,825 and U.S. Pat. No. 5,410,422. Since the rod-shaped liquid crystalline molecules are symmetrically aligned in the upper part and the lower part of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. Therefore, this liquid crystal mode is
(Optically Compensatory Bend) Also called liquid crystal mode. The bend alignment mode liquid crystal display device has an advantage of high response speed.

In the TN mode liquid crystal cell, rod-like liquid crystal molecules are substantially horizontally aligned when no voltage is applied, and further twisted and aligned at 60 to 120 °. The TN mode liquid crystal cell is most often used as a color TFT liquid crystal display device, and is described in many documents.

[0102]

EXAMPLES Example 1 The light-transmitting resin constituting the light diffusing layer was a hard coat liquid containing silica ultrafine particle dispersion (Desolite Z7526, manufactured by JSR Corporation, refractive index 1.51).
00 parts by mass, 25 parts by mass of crosslinked polystyrene beads (Soken Chemical SX130H, particle size 1.3 μm, refractive index 1.61) as translucent particles, crosslinked polystyrene beads (Soken Chemical SX350H, particle size 3.5 μm, Refractive index 1.61) 6 parts by mass, mixing these, methyl ethyl ketone / methyl isobutyl ketone (20/80 mass ratio)
Was adjusted to a solid content of 45% by a triacetyl cellulose film (Fuji Photo Film Co., Ltd.).
Co., Ltd., TD-80U) so that the coating amount of 1.3 μm cross-linked polystyrene beads is 1.1 g / m ² , after solvent drying, 160 W / cm air-cooled metal halide lamp (I Graphics Co., Ltd.) Illumination 400
A light diffusion film A-01 was produced by irradiating with ultraviolet rays of mW / cm ² and a dose of 300 mJ / cm ² to cure the coating layer. The dry film thickness of the light diffusion layer of this film was 3.5 μm.

(Preparation of coating liquid for low refractive index layer) Refractive index 1.
42 thermally crosslinkable fluoropolymers (JN-7228, J
SRK Co., Ltd. 93g MEK-ST (average particle size 10
20 nm, methyl ethyl ketone (MEK) dispersion of SiO2 sol having a solid content concentration of 30% by mass, manufactured by Nissan Chemical Co., Ltd.
8 g and 100 g of methyl ethyl ketone were added and stirred, and then filtered through a polypropylene filter having a pore size of 1 μm to prepare a coating liquid for low refractive index layer.

[Example 2] On the light diffusing layer of the light diffusing film A-01, the above-mentioned coating liquid for low refractive index layer was applied using a bar coater, dried at 80 ° C, and further dried at 120 ° C for 1 hour.
The film was thermally crosslinked for 0 minutes to form a low refractive index layer having a thickness of 0.096 μm, and a light diffusion film A-02 was produced.

[Example 3] Light diffusing film A-0 except that the coating amount of 1.3 µm crosslinked polystyrene beads was changed.
Light diffusion films A-03 to A-07 were produced in the same manner as in 2. The coating amount is as shown in Table 1.

[Example 4] Light diffusion film A- except that 1.3 µm cross-linked polystyrene beads were changed to 1.5 µm silica beads (Nippon Shokubai Seahost KE-P150 refractive index 1.44) and the coating amount was changed. Light diffusion films A-08 to A-09 were prepared in the same manner as in No. 02. The coating amount is as shown in Table 1.

[Embodiment 5] The light-transmitting resin constituting the light-diffusing layer is a hard coat coating liquid containing zirconium oxide ultrafine particle dispersion (Desolite KZ-7114A, JSR Corporation).
100 parts, translucent resin (Nippon Kayaku DPHA
57 parts by mass of the mixture) is mixed by stirring with methyl ethyl ketone /
The coating film obtained by dissolving in a methyl isobutyl ketone (20/80 mass ratio) solution, coating and UV curing had a refractive index of 1.61. As transparent fine particles in this solution,
Polymethylmethacrylate beads (Soken Chemical MX
150 parts, particle size 1.5 μm, refractive index 1.49), and 17 parts by mass, and polymethylmethacrylate beads (manufactured by Soken Kagaku, MX300 particle size 3.0 μm, refractive index 1.49)
Of 7 parts by weight, mixed with these and adjusted to a solid content of 50% with methyl ethyl ketone / methyl isobutyl ketone (20/80 mass ratio), a triacetyl cellulose film (Fuji Photo Film Co., Ltd., TD −
80 U), 1.5 μm polymethylmethacrylate-based beads were coated so that the coating amount was 0.4 g / m ² , after solvent drying, 160 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) Illuminance 400
A light diffusion film B-01 was prepared by irradiating with ultraviolet rays of mW / cm ² and a dose of 300 mJ / cm ² to cure the coating layer. The dry film thickness of the light diffusion layer of this film was 3.0 μm.

[Example 6] The above-mentioned coating liquid for low refractive index layer was coated on the light diffusion layer of the light diffusion film B-01 by using a bar coater, dried at 80 ° C, and further dried at 120 ° C for 1 hour.
The film was thermally crosslinked for 0 minutes to form a low-refractive index layer having a thickness of 0.096 μm, and a light diffusion film B-02 was produced.

[Embodiment 7] Light diffusing films B-03 to B-0 were the same as the light diffusing film B-02 except that the coating amount of the 1.5 μm polymethylmethacrylate beads was changed.
6 was produced. The coating amount is as shown in Table 2.

Example 8 A light diffusion film B-07 was prepared in the same manner as the light diffusion film B-02 except that the 1.5 μm polymethylmethacrylate beads were changed to 5.0 μm polymethylmethacrylate beads.

[Example 9] Light diffusion film B- except that 1.5 µm polymethylmethacrylate beads were changed to 1.3 µm crosslinked polystyrene beads and the coating amount was changed.
In the same manner as in No. 02, light diffusion films B-08 to A-09 were produced. The coating amount is as shown in Table 2.

[Example 10] Light was changed except that the 1.5 μm polymethylmethacrylate beads were changed to melamine formaldehyde beads (Nippon Catalyst Co., Ltd., particle size 0.5 μm, refractive index 1.68), and the coating amount was changed. Diffusion film B-0
A light diffusion film B-10 was produced in the same manner as in 2. The coating amount is as shown in Table 2.

(Evaluation of Light Diffusing Film) The following items were evaluated for the obtained light diffusing film. The results are shown in Tables 1 and 2.

(1) A specular reflectance spectrophotometer V-550 (manufactured by JASCO Corporation) was equipped with an adapter ARV-474, and an emission angle of -5 at an incident angle of 5 ° in a wavelength range of 380 to 780 nm. The specular reflectance was measured, the average reflectance from 450 to 650 nm was calculated, and the antireflection property was evaluated.

(2) Haze A haze meter MODEL was used to measure the haze of the obtained film.
It measured using 1001DP (made by Nippon Denshoku Industries Co., Ltd.).

(3) Evaluation of scattered light profile Using an automatic goniophotometer GP-5 (manufactured by Murakami Color Research Laboratory Co., Ltd.), a light diffusing film was placed vertically with respect to the incident light and The scattered light profile was measured across the azimuth. Scattered light intensity of 30 ° with respect to light intensity of 0 ° exit angle,
The scattered light intensity of 60 ° with respect to the light intensity of the emission angle of 0 ° was obtained. FIG. 2 shows the light diffusion film (A-
02) Scattering profile. In FIG. 2, the concentric intervals are logarithmic.

Next, a polarizing plate was prepared using the light diffusing film of the above-mentioned example and evaluated in a liquid crystal display device.

(Preparation of Polarizing Plate on Viewing Side) Iodine was adsorbed on a stretched polyvinyl alcohol film to prepare a polarizing film. Light diffusion film A-01 to 09 and B-01 to
10 was subjected to saponification treatment, and a polyvinyl alcohol-based adhesive was used to adhere to one side of the polarizing film so that the transparent substrate (triacetyl cellulose) of the light diffusion film was on the polarizing film side. Further, an optical compensation film WVSA12B (manufactured by Fuji Photo Film) having an optically anisotropic layer made of a liquid crystal compound is subjected to saponification treatment, and a polyvinyl alcohol adhesive is used so that the film support is on the polarizing film side. I stuck it on the other side. In this way, the viewing side polarizing plate PA-
01-09 and PB-01-10 were produced.

(Production of Backlight-Side Polarizing Plate) Iodine was adsorbed on a stretched polyvinyl alcohol film to produce a polarizing film. A commercially available triacetyl cellulose film (Fujitac TD80 manufactured by Fuji Photo Film) is saponified, and a polyvinyl alcohol-based adhesive is used.
It was attached to one side of the polarizing film. Further, an optical compensation film WVSA12 having an optically anisotropic layer made of a liquid crystal compound.
B (manufactured by Fuji Photo Film Co., Ltd.) was subjected to saponification treatment, and a polyvinyl alcohol-based adhesive was used to attach the cellulose acetate film to the opposite side so that the film was on the polarizing film side. In this way, a backlight side polarizing plate was produced.

[Example 11] A pair of polarizing plates provided in a liquid crystal display device (6E-A3, manufactured by Sharp Corporation) using a TN type liquid crystal cell was peeled off, and a polarizing plate PA was used instead.
-01 to 09 and PB-01 to 10 through an adhesive so that the optical compensation film is on the liquid crystal cell side,
Attached to the observer side. A polarizing plate on the backlight side was attached to the backlight side via an adhesive so that the optical compensation film was on the liquid crystal cell side. The transmission axis of the observer side polarizing plate and the transmission axis of the backlight side polarizing plate are O
Arranged to be in mode. About the produced liquid crystal display device, a measuring instrument (EZ-Contrast160D, ELDIM
(Manufactured by the company) was used to measure the viewing angle in eight steps from black display (L1) to white display (L8).

Further, an image was displayed on the liquid crystal display device, and the blurring of the image was evaluated in the following three stages. No image blur is noticeable: A Image is slightly blurry: B Image blur is visible: C The results are shown in Tables 1 and 2.

[0122]

[Table 1]

[0123]

[Table 2]

[0124]

[Table 3]

[0125]

[Table 4]

The following are clear from the results shown in Tables 1 and 2. When the light diffusion film having a scattered light intensity ratio of 30 ° / 0 ° of 0.01% or more was processed into a polarizing plate and used in a liquid crystal display device, a remarkable effect of improving the viewing angle was obtained. In particular, the viewing angles in the downward and left and right directions are improved.
However, when the scattered light intensity ratio of 30 ° / 0 ° exceeds 0.2%, the viewing angle widening effect is great, but the image is blurred. Therefore, the scattered light intensity ratio of 30 ° / 0 ° is 0.
With the light diffusion film of 01% to 0.2%, the image was not distorted, and the wide viewing angle of the liquid crystal display device could be achieved.

Further, as is apparent from the table, the light diffusing film laminated with the low refractive index layer and subjected to the antireflection treatment has a low specular reflectance of 2.5% or less and exhibits excellent antireflection properties. . As described above, the light diffusion film, antireflection film, polarizing plate and liquid crystal display device of the present invention show excellent visibility.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a basic structure of a light diffusion film.

FIG. 2 is a light-diffusing film (A-0 produced in Example 2).
It is a scattering profile of 2).

[Explanation of symbols]

10 Light diffusion film 20 Transparent support 30 light diffusion layer 41 Matt particles 1 42 Matt particles 2 50 Low refractive index layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/1335 510 G02B 1/10 AF term (reference) 2H042 BA02 BA12 BA14 BA20 2H049 BA02 BA06 BA27 BA42 BB33 BB43 BB49 BB63 2H091 FA08X FA08Z FA37X FA41Z GA06 GA13 GA16 LA16 2K009 AA04 AA12 BB28 CC09 CC24 4F100 AA20 AK12 AK17 AR00A AR00B AR00C AR00D BA02 BA03 BA04 BA07 BA10A BA10C BA10D GB41 JN00A JN10D JN10D JN10B JN10D

Claims (4)

[Claims] 1. A light diffusion film having a transparent substrate and a light diffusion layer, wherein the light diffusion layer is 0.01 to 0.2%.
The light diffusion film has a scattered light intensity of 30 ° with respect to a light intensity of an emission angle of 0 ° of the scattered light profile of the goniometer in the range of. 2. An antireflection film having a transparent substrate, a light diffusing layer and a low refractive index layer in this order, wherein the light diffusing layer is in the range of 0.01 to 0.2%. The anti-reflection film has a scattered light intensity of 30 ° with respect to a light intensity of an emission angle of 0 ° of the scattered light profile of
An antireflection film having an average value of specular reflectance at 5 degrees incidence in a wavelength range of 450 to 650 nm in a range of 2.5% or less. 3. A polarizing plate having protective films provided on both sides of a polarizing film, wherein one of the protective films is the light diffusion film according to claim 1 or the antireflection film according to claim 2. Polarizing plate characterized by. 4. An image display device using the light diffusion film according to claim 1, the antireflection film according to claim 2, or the polarizing plate according to claim 3 as an outermost layer of a display.