JP2001081291A - Composition for anisotropic light scattering film and anisotropic light scattering film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition suitable for obtaining an anisotropic light scattering film whose scattering characteristics within lengthwise and widthwise scattering ranges can be easily controlled by rendering scattering characteristics anisotropic (causing forward or backward scattering and dependence on an incident angle) and which does not change the color of the display light depending on an observer's position. SOLUTION: The composition comprises at least (A) a bisphenol A type epoxy resin or a brominated bisphenol A type epoxy resin, (B) a compound containing at least one oxirane ring in the molecule, (C) a radically polymerizable compound having a smaller refractive index than those of (A) and (B), and (D) a photoinitiator generating a cation species and a radical species by a chemical radiation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has different scattering properties depending on the incident angle of light (or has incident angle selectivity).
In addition, the present invention relates to a composition for a light diffusion film and a light diffusion film having anisotropic light scattering characteristics.

[0002]

2. Description of the Related Art In a display device utilizing light, such as a reflection type liquid crystal display device or a transmission type liquid crystal display device, a viewing angle at the time of observation is secured (that is, a brightly displayed image is displayed on the front surface of the display device). For example, a light-diffusing film is disposed on the front of the apparatus for the purpose of showing the display screen with uniform brightness over the entire display screen. As a conventional light scattering film, a resin film whose surface is processed into a mat shape, a resin film containing a diffusing material inside, and the like are used.

[0003] In the case of a conventional resin film processed into a mat shape or a film containing a diffusing material inside, it is difficult in principle to provide a function such as a change in scattering depending on the incident angle of incident light. It does not have such a function.

[0004] In the case of a light-scattering film whose surface is processed into a mat shape, the film surface is physically formed with a matte surface as in a sandblaster treatment, or is chemically treated by dissolution treatment with an acidic or alkaline solution. To form Therefore, it is difficult to control the light scattering property, and it is impossible to change the vertical and horizontal scattering properties, so that it is not possible to impart scattering anisotropy.

[0005] In a light-scattering film containing a diffusing material therein, attempts have been made to control the refractive index, size, shape, etc. of the diffusing material in order to control the scattering.
At present, it is technically difficult and not sufficiently practical.

Accordingly, the above-mentioned light-scattering film has no scattering angle dependence and no or little anisotropy of light scattering, so that when used in a display device, unnecessary scattered light is generated. As a result, there is a problem that the brightness and contrast of the display are reduced or the displayed image is blurred.

On the other hand, as a proposal relating to a reflection type liquid crystal display device using a scattering plate having anisotropic light scattering, Japanese Patent Application Laid-Open No. Hei 8-2
No. 01802 is known. The scattering plate disclosed in the above publication is a scattering plate having almost no back scattering characteristics and strong forward scattering characteristics, and selectively scatters either the incident light to the liquid crystal display device or the display light emitted from the liquid crystal display device. It has the properties to make

However, the above publication does not specifically describe the structure of the scattering plate, but only describes "the transparent fine particles hardened with a transparent polymerizable polymer".

In such a scattering plate, as in the case of the above-mentioned "light diffusion film containing a diffusing material therein", even if the scattering characteristics are given anisotropy (forward or backward), the scattering plate is vertically oriented. It is difficult to control even the lateral scattering characteristics.

As a proposal for a transmission type liquid crystal display device using a hologram as a scattering plate, Japanese Patent Application Laid-Open No. Hei 9-152
No. 602 is known. The above proposal scatters display light emitted from a liquid crystal display device having a backlight, and employs a hologram as a scattering plate. Although it is possible to control the horizontal scattering characteristics, it is inevitably accompanied by spectral dispersion (wavelength dispersion), so that the color of the display light changes and is visually perceived as the viewpoint to be observed is moved. Will be.

In order to solve the above-mentioned problems, the present applicant provides the scattering characteristics with anisotropy (forward or backward, and dependence on the incident angle), and makes the scattering characteristics related to the vertical and horizontal scattering ranges. An application of an anisotropic light-scattering film that can be easily controlled even when the display light color does not change depending on the observation position has been filed (Japanese Patent Application No. 10-346743).

[0012]

It is an object of the present invention to provide a composition suitable for obtaining the anisotropic light-scattering film and an anisotropic light-scattering film produced therefrom.

[0013]

SUMMARY OF THE INVENTION According to the present invention, it is possible to provide anisotropic scattering properties (depending on the forward or backward direction and the incident angle) and to control the scattering properties in the vertical and horizontal scattering ranges. An object of the present invention is to provide a composition for obtaining an anisotropic scatterer that is easy and does not change the color of display light depending on the observation position.

[0014]

According to the present invention, at least a bisphenol A type epoxy resin or a brominated bisphenol A type epoxy resin (A) and a compound having at least one oxirane ring in the molecule are provided. It contains (B), a compound (C) having a lower refractive index than the above (A) and (B) and having radical polymerizability, and a photoinitiator (D) that generates a cationic species and a radical species by actinic radiation. It is a composition for an anisotropic light-scattering film characterized by the above-mentioned. The invention described in claim 2 is the first invention.
A composition for an anisotropic light-scattering film, further comprising a sensitizing dye (E) for sensitizing the above (D), on the premise of the invention described in the above. According to a third aspect of the present invention, there is provided a composition for an anisotropic light-scattering film, wherein (A) has an epoxy equivalent of 400 to 5,000, based on the first aspect. The invention described in claim 4 is based on the premise of the invention described in claim 1, and (C)
A composition for an anisotropic light-scattering film, which is a compound which is liquid at normal temperature and pressure and has at least one ethylenically unsaturated bond having a boiling point of 100 ° C. or higher at normal pressure. The invention according to claim 5 is based on the invention according to claim 1, and based on 100 parts by weight of (A).
A composition for an anisotropic light-scattering film, which is obtained by mixing 20 to 80 parts by weight of the component (C). The invention according to claim 6 is an anisotropic light-scattering film obtained by exposing and curing the composition for anisotropic light-scattering film according to claims 1 to 5.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The anisotropic light-scattering film of the present invention (hereinafter simply referred to as a light-scattering film) has a refractive index in which portions having different refractive indexes are distributed in an irregular shape and thickness inside the film. A light and shade pattern consisting of high and low is formed, and the size, shape, distribution of the parts with different refractive indices,
By optimizing along the vertical and horizontal directions on the film surface and along the thickness direction of the film, the scattering characteristics depending on the incident angle can be changed, and light scattering in unnecessary directions can be eliminated. The light is scattered only in the range. The production is carried out by exposing and curing a composition for an anisotropic light-scattering film comprising a cationically polymerizable compound and a radically polymerizable compound, each having a different refractive index.

Here, the light and shade pattern having a high and low refractive index is formed by radical species generated by the photoinitiator (D) according to the light intensity. The generated radical species is (A)
And (B) having a lower refractive index than the compound (C) having radical polymerizability and acting as a polymerization initiator for the compound (C)
Polymerization begins. At this time, the polymerization proceeds by the diffusion transfer of the nearby compound (C), but the radical polymerization of the compound (B) having at least one oxirane ring in the molecule does not occur. The concentration of (C) decreases and the concentration of (B) increases. At this time, since (B) also functions as a plasticizer, it promotes diffusion and transfer of (C), and is extruded from a portion having a high light intensity by polymerization of (C), and is extruded from a portion having a low light intensity. (B) is increased. Since (B) has a higher refractive index than (C), a light and shade pattern having a higher or lower refractive index is formed according to the light intensity. Finally, the unreacted (C) undergoes radical polymerization due to the entire surface exposure using UV or the like, and further the carrier (A)
Alternatively, (B) is fixed by cationic polymerization.

Hereinafter, the present invention will be described with reference to the drawings.
FIG. 1 shows that the portions having different refractive indices are distributed in an irregular shape and thickness, and the refractive index is high and low (in FIG. 1, it is represented by white and black).
It is an explanatory view showing the light-scattering film 1 on which a light and shade pattern composed of is formed, where the left is a plan view and the right is a cross-sectional view.

As can be seen from the plan view, the shape of the portion having a different refractive index is horizontally long. Further, as can be seen from the cross-sectional view, the portions having different refractive indexes have a structure distributed in a layer shape inclined with respect to the thickness direction of the film. In FIG. 1, the distribution of the refractive index is uniform (the color does not change in the inclined direction) in the direction in which the portions having different refractive indexes are inclined in layers.

FIG. 2 is an explanatory view showing a light-scattering film 1 according to another embodiment, wherein the left is a plan view and the right is a cross-sectional view. In FIG. 2, the shape of the portion having a different refractive index is vertically long,
In addition, in the direction in which the portions having different refractive indices are inclined in a layered manner, the distribution of the refractive index is irregular (the color changes even in the inclined direction).

First, the optical characteristics of the light-scattering film shown in FIGS. Light scattering occurs for light incident at an angle along the above-mentioned inclination direction in which portions having different refractive indices are distributed in layers (an angle θ from the perpendicular to the film, in the direction of arrow 2 in FIG. 2). Become.

An angle perpendicular to the inclination direction (arrow 3 in the figure)
), It functions as a mere transparent film, and the incident light exits without being scattered.

Next, considering a plan view, when the shape of the portion having a different refractive index is vertically long (or horizontally long), when the light incident on that portion is scattered and emitted, It has anisotropy such that the light scattering characteristics are horizontally long (or vertically long). In FIG. 1, the emitted light is scattered vertically because the shape is horizontal, and in FIG. 2, the emitted light is scattered horizontally because the shape is vertical.

FIG. 3 is a graph showing an example of the incident angle dependence of the light scattering film 1 produced using the composition of the present invention. As shown by the solid line in the figure, the haze value is 80% or more for light in a certain specific incident angle range (0 to 60 degrees in the figure), and conversely, the incident angle is symmetrical to that (−60 degrees in the figure). Haze value is 20%
This shows the incident angle dependence of the scattering property referred to in this specification.

Further, as described above, when the shape of the portion having a different refractive index is vertically long (or horizontally long), when the light incident on the portion is scattered and emitted, the light emitted from each portion is emitted. It has anisotropy such that its scattering characteristics are horizontally long (or vertically long). For example, if the shape is horizontally long as shown in FIG. 1, the scattered light emitted from the light scattering film has a distribution such that it becomes a vertically long ellipse as shown in FIG.

Next, the composition for an anisotropic light scattering film of the present invention will be described in detail. As described above, the inside of the anisotropic light-scattering film made of the composition of the present invention forms a light and shade pattern composed of high and low refractive indexes by distributing portions having different refractive indexes in an irregular shape and thickness. Have been.

If the difference in the refractive index is too small, the scattering property deteriorates. On the contrary, if the difference is too large, light scattering occurs regardless of the incident angle of the light. It becomes difficult to have dependencies.

The bisphenol A type epoxy resin or brominated bisphenol A type epoxy resin (A) used in the composition of the present invention is a resin represented by the general formula (I), which is crosslinked by heating in the presence of a cationic species. Occurs and hardens. In addition, the epoxy equivalent is 400-5.
000 is desirable. When the epoxy equivalent is 400 or less, the epoxy compound becomes a liquid epoxy and does not play the role of a carrier, and when it is 5000 or more, the aliphatic compound (D) having at least one (meth) acryloyl group in the molecule.
The cross-linking density of the cured resin does not increase because the cross-linking point of the resin decreases while diffusion movement of the resin hardly occurs.
This is because heat resistance is reduced.

[0028]

Embedded image

(Where R is a hydrogen atom or a bromine atom, and n is a real number satisfying an epoxy equivalent of 400 to 5000).

The compound (B) having at least one oxirane ring in the molecule used in the composition of the present invention needs to have a high refractive index, and may be liquid when heated after exposure. desirable. The compound is
When a compound having one or more polymerizable ethylenic double bonds in a molecule is present as a liquid when polymerizing, diffusion diffusion of a compound having one or more polymerizable ethylenic double bonds in a molecule is prevented. It plays a role of a so-called plasticizer to make it easy to occur, so that it hardens when the resin is hardened, because it exists as a polymer in the anisotropic scattering film, there is no adverse effect such as thermal deterioration, Since the refractive index is higher than that of the compound having one or more polymerizable ethylenic double bonds in the molecule, the scattering property is not adversely affected.

Specifically, glycidyl phenyl ether, p-bromophenyl glycidyl ether, glycidyl-1-naphthyl ether, glycidyl-2-naphthyl ether, glycidyl indaryl ether, benzothiazolyl glycidyl ether, bisphenol A diglycidyl ether , Bisphenol A alkyloxydiglycidyl ether, their derivatives, alicyclic epoxy compounds, and the like, but are not limited thereto.

The compound (C) having radical polymerizability is a compound having radical polymerizability that is polymerized or cross-linked by irradiation with actinic radiation in the presence of an initiator that generates a radical by actinic radiation. The unit contains at least one ethylenically unsaturated bond, contains a polyfunctional vinyl monomer in addition to a monofunctional vinyl monomer, and may be a mixture thereof. Further, the compound needs to have a lower refractive index than the epoxy resin (A) and the compound (B) having an oxirane ring.

More specifically, high-boiling vinyl monomers such as (meth) acrylic acid, itaconic acid, maleic acid, (meth) acrylamide, diacetone acrylamide, and 2-hydroxyethyl (meth) acrylate; Hydroxy compounds, such as ethylene glycol,
Diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, neopentyl glycol, 1,3-propanediol, 1,4
-Butanediol, 1,5-pentanediol, 1,6
Di- or poly (meth) acrylates such as -hexanediol, 1,10-decanediol, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitol, and mannitol; and the like, but are not limited thereto.

It is preferable that (C) is a liquid at normal temperature and normal pressure and has a boiling point of 100 ° C. or higher at normal pressure. This is because it is preferably a liquid in order to facilitate diffusion and movement in the resin, and also because it does not volatilize during coating and drying.

Further, it is preferable that 20 to 80 parts by weight of (C) is mixed with 100 parts by weight of (A). If it is out of this range, the concentration distribution due to the diffusion movement of (C) cannot be performed, and as a result, the difference in the refractive index according to the light intensity is reduced, and the scattering property is reduced or the scattering property is not exhibited.

The photoinitiator system (D) for generating radical species and cationic species by actinic radiation used in the composition of the present invention is described in J. Am. Photochem. Sc
i. Technol. , 2,283 (1987). Compounds, specifically iron arene complex, trihalogenomethyl-substituted s-triazine, sulfonium salt, diazonium salt, phosphonium salt, selenonium salt,
Arsonium salts, iodonium salts and the like, and examples of iodonium salts include Macromolecule
s, 10, 1307 (1977). And diphenyliodonium, ditolyliodonium, phenyl (p-anisyl) iodonium, bis (m
-Nitrophenyl) iodonium, bis (p-tert)
Iodonium chlorides such as -butylphenyl) iodonium and bis (p-chlorophenyl) iodonium;
Examples thereof include bromide, a borofluoride salt, a hexafluorophosphate salt, a hexafluoroarsenate salt, and an aromatic sulfonate.

The sensitizing dye (E) for sensitizing the photoinitiator (D) which generates a cationic species and a radical species by actinic radiation according to the present invention includes Michler's ketone,
Organic dye compounds such as benzophenone derivatives such as 4,4'-bis (diethylamino) benzophenone, cyanine or merocyanine derivatives, coumarin derivatives, chalcone derivatives, xanthene derivatives, thioxanthene derivatives, azurenium derivatives, squarylium derivatives, and porphyrin derivatives can be used. "Dye Handbook"
(Shin Okawara et al., Kodansha 1986), "Chemistry of functional dyes" (Shin Okawara et al., CMC, 1981),
"Special Functional Materials" (Chemaburo Ikemori et al., CMC, 1
986) are used. It should be noted that the present invention is not limited to these, and any other dyes and sensitizers that absorb light in the visible region can be used. These may be used in two or more at any ratio as needed.

The amount of the photoinitiator contained in the composition of the present invention is 0.1 to 100 parts by weight of the bisphenol A type epoxy resin or the brominated bisphenol A type epoxy resin.
It is 1 to 20 parts by weight, preferably 1 to 10 parts by weight. Further, the amount of the sensitizer is determined based on the amount of bisphenol A type epoxy resin or brominated bisphenol A type epoxy resin 1
It can range from 0.1 to 10 parts by weight, preferably from 0.5 to 5, based on 00 parts by weight. The amount used is restricted by the thickness of the photosensitive layer, the optical density at the thickness, or the color of the anisotropic light-scattering film after production.
That is, it is preferable to use the resulting anisotropic light-scattering film in an amount close to colorless as long as the optical density does not exceed 2.

As described above, these components are appropriately selected, and the photosensitive solution obtained by mixing them at an arbitrary ratio is coated with a known coating means such as a bar coater, an applicator, a doctor blade, a roll coater, a die coater, and a comma coater. Is applied to a substrate such as a glass plate or a film.

When the photosensitive liquid is applied, it may be diluted with an appropriate solvent if necessary. In that case, however, it is necessary to apply the solvent on a substrate and then dry it. Examples of the solvent include dichloromethane, chloroform, acetone, 2-butanone, cyclohexanone, ethyl acetate, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, 2-methoxy Ethyl ether,
2-ethoxyethyl ether, 2- (2-ethoxyethoxy) ethanol, 2- (2-butoxyethoxy) ethanol, 2- (2-ethoxyethoxy) ethyl acetate, 2- (2-butoxyethoxy) ethyl acetate,
Examples include tetrahydrofuran and 1,4-dioxane.

Furthermore, the difference in the refractive index that can be recorded is limited by the manufacturing method, the recording material, and the like. Therefore, when the refractive index difference is large, the film thickness is small, and when the refractive index difference is small, the film thickness is small. By increasing the thickness, a light-scattering film can be realized using the composition of the present invention.

The photosensitive material using the composition for a light-scattering film of the present invention may be subjected to a heat treatment at 50 to 120 ° C. after exposure to promote the diffusion and transfer of (C).

The size of the portions having different refractive indices is random and non-regular in order to cause light scattering. However, in order to have necessary scattering properties, the average size is 0.1 μm to 300 μm in diameter. It is appropriately selected within the range according to the scattering property required for each application.

The distribution of the portions having different refractive indices on the film surface is random and irregular in order to cause light scattering, but in order to have necessary scattering properties, the average refractive index of the entire film is required. Is defined as <n>, the probability distribution exhibits a normal distribution centered on <n>. Alternatively, the refractive index n may be distributed according to a probability distribution that takes a maximum value at a minimum value n _min and monotonically decreases exponentially to a maximum value n _max of the refractive index, or a probability distribution that monotonically increases.

Hereinafter, means for producing the light scattering film of the present invention will be described. The light scattering film of the present invention can be produced by an optical exposure means. FIG. 5 is an explanatory diagram showing an example of an optical system manufactured using a random mask pattern. Ultraviolet light emitted from the UV light source 6 is converted into collimated light 8 by a collimating optical system 7 to irradiate a mask master 9.

The photosensitive material 5 is disposed in close contact with the surface of the mask master 9 opposite to the UV irradiation side, and the pattern of the mask master 9 is exposed to light. At this time, since the UV parallel light 8 and the mask master 9 are arranged at a predetermined angle α as shown in the figure, the pattern exposure is performed at a predetermined angle in the photosensitive material 5. This angle is
The angle corresponds to the angle of inclination of a portion having a different refractive index in the light scattering film (that is, the scattering angle θ depending on the incident angle). Therefore, the angle is appropriately set in the range of about 0 to 60 degrees depending on the application. select.

The photosensitive material 5 used here is UV
A photosensitive material that can record exposed and unexposed areas of light in the form of changes in the refractive index. It must have a higher resolving power than the density pattern to be recorded, and be capable of recording patterns in the thickness direction. There is.

The mask master 9 having a predetermined random pattern used in FIG. 5 converts black-and-white pattern data created by random number calculation using a computer into a metal chromium pattern 11 on a glass substrate 10 by a so-called photolithography technique. Etched ones may be used. Of course, the method of producing the mask master is not limited to the above-mentioned method, and it is well known that a similar mask can be produced by a lithography method using a squirrel plate.

FIG. 6 is an explanatory view showing an example of an optical system for producing a light scattering film having the structure shown in FIG. 2 using a speckle pattern. A ground glass 15 is irradiated with laser light 14 emitted from a laser light source 13. Ground glass 15
The photosensitive material 5 is disposed at a predetermined distance F on the surface opposite to the laser irradiation side, and the photosensitive material 5 is exposed and irradiated with a speckle pattern, which is a complicated interference pattern generated by laser light transmitted and scattered by the ground glass 15. Is done.

At this time, the frosted glass 10 and the photosensitive material 5 are arranged at a predetermined angle α as shown in FIG.
The speckle pattern is exposed at a predetermined angle in the photosensitive material. Since this angle corresponds to the inclination of the portion having a different refractive index in the light scattering film (that is, the scattering peak angle θ depending on the incident angle), the angle is about 0 to 60 degrees depending on the application. Select appropriately within the range.

The laser light source used for recording was an argon ion laser or a krypton ion laser of 647.9.
nm, 514.5 nm, 488 nm, 457.9 nm or 413 nm can be appropriately selected and used according to the sensitivity of the photosensitive material. In addition, other than an argon ion laser, any laser light source having good coherence can be used. For example, a helium neon laser or a semiconductor laser can be used.

The speckle pattern is a bright and dark spot pattern generated when light having good coherence is scattered and reflected or transmitted on a rough surface, and light scattered by minute irregularities on the rough surface interferes in an irregular phase relationship. It is caused by

According to the description of the “Light Measurement Handbook (Asakura Shoten, written by Toshiharu Tamitsu et al., Published on November 25, 1994)” (p. 266 to p. 268), the density and phase are random values depending on the position. In the speckle pattern as shown in the following expression, the average size of the pattern is determined in inverse proportion to the angle at which the diffusion plate is viewed from the photosensitive material. Therefore, when the size of the diffusion plate is made larger in the vertical direction than in the horizontal direction, the pattern recorded on the photosensitive material is finer in the vertical direction than in the horizontal direction.

The speckle pattern according to the manufacturing method using the optical system shown in FIG. 6 is such that the wavelength λ of the laser beam to be used, the size D of the ground glass, and the distance F between the ground glass and the photosensitive material are as follows.
The average size d of the speckle pattern to be recorded is determined, and is generally expressed by the following equation. d = 1.2λF / D The average length t of this speckle pattern in the depth direction is represented by t = 4.0λ (F / D) ² .

As described above, the light scattering film of the present invention having a desired three-dimensional refractive index distribution can be obtained by optimizing the values of λ and F / D so as to have an optimum scattering property.

As an example, when λ = 0.5 μm, F / D =
Assuming that 2, d = 1.2 μm and t = 8 μm, the light and shade pattern on the film surface is distributed at an average of 1.2 μm, and the average in the film thickness direction is 8 μm in a direction according to the inclination angle.
m will be distributed.

However, these sizes are merely average sizes. In practice, portions having different sizes and different refractive indexes are distributed on the surface and inclined in the depth direction. The light scattering film of the present invention as shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to specific examples.

Example 1 100 parts by weight of a bisphenol A type epoxy resin (EP1007, trade name of Yuka Shell Epoxy Co., Ltd., epoxy equivalent: 1750-2200),
Tripropylene glycol diacrylate (VISCO
AT-310HP, manufactured by Osaka Organic Chemical Co., Ltd.) 50
Parts by weight, 30 parts by weight of glycidyl phenyl ether, and 5.0 parts by weight of 4,4′-bis (tert-butylphenyl) iodonium hexafluorophosphate,
4,4'-bis (diethylamino) benzophenone
A solution prepared by mixing and dissolving 2 parts by weight in 100 parts by weight of 2-butanone was used as a photosensitive solution. The photosensitive solution was transferred to a blue plate glass (1.1 mm
(5 inch square) with a doctor blade and dried to obtain a photosensitive material.

The photosensitive material is exposed from the surface of the photosensitive material through a ground glass 15 by using a light obtained by expanding a krypton laser (413 nm) as a light source using a lens in the optical system shown in FIG. 6 (α = 22 °). , 10mJ / cm ² ), 85 ° C
After heating for 5 minutes at, the entire surface of the recording medium was irradiated with a high-pressure mercury lamp to fix the recording medium. Furthermore, a light-scattering film was obtained by peeling the cured product from the glass substrate. The thickness of the resulting film was 29 microns.

For evaluation, transmittance (wavelength range: 400 to 600 nm) was measured at each angle using a spectrophotometer manufactured by Shimadzu Corporation. Table 1 shows the results (average transmittance of all wavelengths).

[Table 1] Measurement angle (°) 0 10 20 22 25 30 40 Transmittance (%) 85 85 84 74 26 12 12

Example 2 A light-scattering film was produced in the same manner as in Example 1 except that p-bromophenyl glycidyl ether was used instead of glycidyl phenyl ether. The thickness of the resulting film was 29 microns. Table 2 shows the results.

[Table 2] Measurement angle (°) 0 10 20 22 25 30 40 Transmittance (%) 84 84 82 66 20 10 10

Example 3 Instead of glycidyl phenyl ether, bisphenol A type epoxy compound (XB4
Example 1 except that No. 122 (trade name, manufactured by Asahi Chiba Corporation) was used.
The same operation as described above was carried out to obtain the produced light-scattering film. The thickness of the film obtained was 25 microns. Table 3 shows the results.

[Table 3] Measurement angle (°) 0 10 20 22 25 30 40 Transmittance (%) 86 86 80 66 34 25 25

<Example 4> Instead of 4,4'-bis (diethylamino) benzophenone, carbonylbis (p
-Dimethylaminobenzylidene), and a light-scattering film was produced in the same manner as in Example 1 except that an argon laser (514.5 nm) was used instead of a krypton laser (413 nm) as a light source. The thickness of the obtained film was 30 microns. Table 4 shows the results.

[Table 4] Measurement angle (°) 0 10 20 22 25 30 40 Transmittance (%) 80 80 80 65 35 15 15

Example 5 Instead of tripropylene glycol diacrylate (VISCOAT-310HP, trade name of Osaka Organic Chemical Co., Ltd.), neopentyl glycol diacrylate (VISCOAT-215, trade name of Osaka Organic Chemical Co., Ltd.) was used. ) Was carried out in the same manner as in Example 1 except that (1) was used to obtain a produced light-scattering film. The thickness of the film obtained was 31 microns. Table 5 shows the results
Shown in

[Table 5] Measurement angle (°) 0 10 20 22 25 30 40 Transmittance (%) 83 83 82 78 53 26 26 26

<Example 6>4,4'-bis (tert-
A light-scattering film was produced in the same manner as in Example 1 except that trichloromethyltriazine was used instead of (butylphenyl) iodonium hexafluorophosphate. The resulting film had a thickness of 28 microns. Table 6 shows the results.

[Table 6] Measurement angle (°) 0 10 20 22 25 30 40 Transmittance (%) 82 82 78 59 32 15 14

Example 7 Instead of 100 parts by weight of bisphenol A type epoxy resin (EP1007, trade name of Yuka Shell Epoxy Co., Ltd., epoxy equivalent: 1750-2200), bisphenol A type epoxy resin (EP100) was used.
7, Yuka Shell Epoxy Co., Ltd. 60 parts by weight and brominated bisphenol A type epoxy resin (YL616)
7, a light-scattering film was produced in the same manner as in Example 1 except that a mixed system of 40 parts by weight (trade name, manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent: 2100 to 2300) was used. The resulting film had a thickness of 28 microns. Table 7 shows the results.

[Table 7] Measurement angle (°) 0 10 20 22 25 30 40 Transmittance (%) 80 80 76 49 30 12 11

<Comparative Example> A light-scattering film was prepared in the same manner as in Example 1 except that glycidylphenyl ether was not added, but no scattering property was exhibited. The thickness of the obtained film was 30 microns.

[0076]

The light-scattering film using the composition according to the present invention scatters light with respect to light incident at a predetermined angle, and functions as a transparent film with respect to light perpendicular to the light. By this, the light scattering property has an incident angle selectivity, so that light that requires scattering property and light that does not require scattering property can be separated by the angle of incidence on the film, and as a result, it is used in display devices and the like. When used, there is an effect that the brightness, fineness and contrast of the display are improved without unnecessary scattering, and that the blur of the display image is reduced.

Further, when light is incident at an incident angle at which light scattering occurs, it is possible to produce a film having a scattering anisotropy in which the spread of the scattered light differs vertically and horizontally.
Therefore, scattered light can be emitted only in a necessary direction. As a result, when used in a display device or the like, there is an effect of improving display brightness and contrast without generating unnecessary scattering.

[0078]

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a light scattering film of the present invention,
The left is a plan view and the right is a cross-sectional view.

FIG. 2 is an explanatory view showing a light scattering film of the present invention;
The left is a plan view and the right is a cross-sectional view.

FIG. 3 is a graph showing an example of the incident angle dependency of the light scattering film of the present invention.

FIG. 4 is an explanatory diagram of anisotropic light scattering of the light scattering film of the present invention.

FIG. 5 is an explanatory view showing an example of an optical system for producing a light scattering film having the structure shown in FIG. 1 using a mask pattern.

FIG. 6 is an explanatory view showing an example of an optical system for producing a light scattering film having the structure shown in FIG. 2 using a speckle pattern.

[Explanation of symbols]

 Reference Signs List 1 light scattering film 2 illumination light incident from scattering direction 3 illumination light incident from transmission direction 4 plot of actually measured haze value 5 photosensitive material 6 UV light source 7 collimate optical system 8 parallel light 9 mask original plate 10 glass substrate 11 chrome pattern 12 Optical fiber 13 Laser light source 14 Laser light 15 Ground glass 16 Beam expander 17 Collimator

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F071 AA42 AC04 AE06 AF35 BA02 BB02 BB12 BC01 4J002 CD051 CD052 CD121 EB008 EE039 EF047 EF077 EH077 EL026 EP017 EQ018 EU188 EV298 EW178 EY008 FD099 FD208 FD209 GQ00

Claims (6)

[Claims] 1. At least a bisphenol A type epoxy resin or a brominated bisphenol A type epoxy resin (A), a compound (B) having at least one oxirane ring in the molecule, and the compounds (A) and (B) A composition for an anisotropic light-scattering film comprising: a compound (C) having a lower refractive index and having radical polymerizability; and a photoinitiator (D) that generates a cationic species and a radical species by actinic radiation. 2. The composition for an anisotropic light-scattering film according to claim 1, further comprising a sensitizing dye (E) for sensitizing said (D). 3. The method according to claim 1, wherein (A) has an epoxy equivalent of 400 to 500
The composition for an anisotropic light-scattering film according to claim 1, wherein the composition is 0. 4. The compound according to claim 1, wherein (C) is a compound which is liquid at normal temperature and pressure and has at least one ethylenically unsaturated bond having a boiling point of 100 ° C. or higher at normal pressure. Item 6. The composition for an anisotropic light-scattering film according to Item 1. 5. The composition for an anisotropic light-scattering film according to claim 1, wherein 20 to 80 parts by weight of (C) is mixed with 100 parts by weight of (A). 6. An anisotropic light scattering film obtained by exposing and curing the composition for an anisotropic light scattering film according to claim 1.