JP2001221907A - Composition for anisotropic light-scattering film and anisotropic light-scattering film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anisotropic scattering film and a composition in which the scattering characteristics are anisotropic (forward or backward scattering and dependence on the incident angle) and the scattering characteristics concerning to the longitudinal and lateral scattering range can be also controlled, and colors of the display light do not change without depending on the observation position. SOLUTION: The composition consists of at least a cation polymerizable compound, a radical polymerizable compound, a photopolymerization initiator which produces radicals by actinic rays, and a thermal polymerization initiator which generates cations by heat, and the refractive index of the cation polymerizable compound differs from that of the radical polymerization compound. The anisotropic scattering film is produced by using that composition to produce portions having different refractive indices distributed with irregular forms and thickness. In the film, a dense and thin pattern with different refractive indices is formed in such a manner that the portions with different refractive indices are distributed in layers inclined from the thickness direction of the film.

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 having anisotropic light scattering characteristics and an anisotropic light diffusion film.

[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 dependency 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 display are reduced or a 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. 0180 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 "light diffusion film containing a diffusion material therein", even if the scattering characteristics are given anisotropy (forward or backward), the scattering in the vertical and horizontal directions is not possible. It is difficult to control even the characteristics.

As a proposal for a transmission type liquid crystal display device using a hologram as a scattering plate, see Japanese Patent Application Laid-Open No. 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.

[0010]

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. It is an object of the present invention to provide a composition and an anisotropic scattering film that are easy and obtain an anisotropic scattering film in which the color of display light does not change depending on the observation position.

[0011]

According to the anisotropic scattering film of the present invention, a portion having a different refractive index is distributed in an irregular shape and thickness inside the film, so that a light and shade pattern having a high and low refractive index is obtained. By changing the size, shape, and distribution of the parts with different refractive indexes along the vertical and horizontal directions on the film surface and along the thickness direction of the film, the scattering characteristics change depending on the incident angle. And eliminates light scattering in unnecessary directions and scatters light only in necessary directions (ranges). The composition for an anisotropic scattering film according to the present invention has a refractive index of It is characterized by having a difference and comprising a cationically polymerizable compound and a radically polymerizable compound.

That is, the composition for an anisotropic light-scattering film according to claim 1 comprises at least (A) a compound having cationic polymerizability, (B) a compound having radical polymerizability, and (C) a compound having actinic radiation. Refractive indices of (A) a compound having cationic polymerizability and (B) a compound having radical polymerizability, comprising a photopolymerization initiator which generates radical species, and (D) a thermal polymerization initiator which generates cationic species by heat. Are characterized by a difference in

A composition for an anisotropic light-scattering film according to claim 2, wherein the compound (A) having cationic polymerizability has an epoxy equivalent of from 400 to 2,200.
Characterized in that it is a type epoxy resin or a brominated bisphenol A type epoxy resin.

In the composition for an anisotropic light-scattering film according to claim 3, the compound (B) having radical polymerizability has a lower refractive index than the compound (A) having cationic polymerizability, At 100 ° C at normal pressure and liquid
It is a compound having at least one ethylenically unsaturated bond as described above.

The composition for an anisotropic light-scattering film according to claim 4, wherein the compound (A) 1 having the cationic polymerizability is used.
20 to 80 parts by weight of the compound (B) having radical polymerizability is mixed with 00 parts by weight.

[0016] The composition for an anisotropic light-scattering film according to claim 5 is characterized in that a sensitizing dye (E) for sensitizing a photoinitiator (C) which generates a radical species by the actinic radiation is added. I do.

The anisotropic light-scattering film according to claim 6 is produced by using the composition for anisotropic light-scattering film according to any one of claims 1 to 5, and the portion having a different refractive index is irregular inside the film. By distributing by shape and thickness,
A light and shade pattern having a high and low refractive index is formed, and portions having different refractive indices are distributed in a layered manner inclining with respect to the thickness direction of the film. Light scattering occurs for light incident at an angle,
It functions as a mere transparent film with respect to light perpendicular to the above-mentioned tilt direction, and has an incident angle selectivity in light scattering.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 shows that the portions having different refractive indexes have irregular shapes.
Explanatory diagram showing an anisotropic light-scattering film (hereinafter, also simply referred to as a light-scattering film) 1 in which a light and shade pattern composed of high and low refractive indexes (expressed in white and black in the figure) is formed and distributed in thickness. 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, in which the left is a plan view and the right is a 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 the plan view, if the shape of the portion having a different refractive index is vertically long (or horizontally long), and the light incident on the 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 specific incident angle range (0 ° to 60 ° in the figure), and conversely, the incident angle is symmetric (−60 ° 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 a portion having a different refractive index is vertically long (or horizontally long), when light incident on the portion is scattered and emitted, the light emitted from each portion is not emitted. It has anisotropy such that the 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.

Numerically expressing this difference in refractive index is 0.0
05 or more and 0.25 or less, more preferably 0.01 or more and 0.25 or less. If the value is smaller than this value, the scattering property deteriorates, and if the value is too large, light scattering occurs regardless of the angle of light incident, and it is possible to have the incident angle dependence of the scattering property. It will be difficult.

(A) used in the composition of the present invention
A compound having cationic polymerizability is a compound having cationic polymerizability that is polymerized or cross-linked by actinic radiation in the presence of an initiator that generates cations by actinic radiation, such as an epoxy compound, a cyclic ether compound, or a cyclic compound. It comprises one or a mixture of two or more of a lactone compound, a cyclic acetal compound, a cyclic thioether compound, a spiroorthoester compound and a vinyl compound. Among such cationically polymerizable compounds, a compound having at least one epoxy group in one molecule is preferable, and examples thereof include conventionally known aromatic epoxy resins and alicyclic epoxy resins.

Preferred as the aromatic epoxy resin is a polyglycidyl ether of a polyhydric phenol having at least one aromatic ring or an alkylene oxide adduct thereof, such as bisphenol A or an alkylene oxide adduct thereof and epichlorohydrin. Glycidyl ether and epoxy novolak resin produced by the reaction are exemplified. Bisphenol A, Bisphenol AD, Bisphenol B, Bisphenol A
Epoxy compounds produced by a condensation reaction of various phenol compounds of F, bisphenol S, brominated bisphenol A, novolak, o-cresol novolak, and p-alkylphenol novolak with epichlorohydrin can be mentioned. Since the brominated bisphenol A epoxy compound becomes insoluble in a solvent when the epoxy equivalent is increased, it is effective to use the epoxy compound in a mixed system without using it alone.

Representative examples of the alicyclic epoxy resin include hydrogenated glycidyl ethers produced by the reaction of the above bisphenol A or an alkylene oxide adduct thereof with epichlorohydrin, particularly hydrogenated bisphenol A, hydrogenated bisphenol AD, Hydrogenated bisphenol B,
Examples include hydrogenated bisphenol AF, hydrogenated bisphenol S, hydrogenated brominated bisphenol A, and the like.

Among the compounds having cationic polymerizability, the molecular weight is 400, except for epoxy compounds formed by the condensation reaction of various phenolic compounds such as volak, o-cresol novolak and p-alkylphenol novolak with epichlorohydrin. If it is smaller than 1,000, it becomes a liquid and cannot be obtained as a film unless a curing treatment by pre-treatment is performed, so that uniform coating cannot be performed. If the molecular weight is larger than this range, no characteristics can be obtained.

(B) used in the composition of the present invention
A compound having radical polymerizability is a compound having radical polymerizability that is polymerized or cross-linked by actinic radiation in the presence of an initiator that generates radicals by actinic radiation. It contains at least one or more unsaturated bonds, contains a polyfunctional vinyl monomer in addition to a monofunctional vinyl monomer, and may be a mixture thereof.

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, tripropylene glycol, neopentyl glycol, 1,3
-Propanediol, 1,4-butanediol, 1,5
-Pentanediol, 1,6-hexanediol, 1,
Mono-, di- or poly (meth) acrylates such as 10-decanediol, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitol, mannitol and the like are exemplified, but not limited thereto.

(C) used in the composition of the present invention
Examples of photopolymerization initiator systems that generate radical species by actinic radiation include benzylmethyl ketals such as 2,2-dimethoxy-1,2-diphenylethan-1-one,
Α-hydroxy ketones such as hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropane-1
-One, 2-benzyl-2-dimethylamino-1- (4
Α-aminoketones such as -morpholinophenyl) butanone-1, bis (2,6-dimethoxybenzoyl)-
Bisacylphosphine oxides such as 2,4,4-trimethylpentylphosphine oxide;
'-Bis (o-chlorophenyl) -4,4', 5,5
Bisimidazoles such as'-tetraphenyl-1,1'-biimidazole and bis (2,4,5-triphenyl) imidazole, N-arylglycines such as N-phenylglycine, and 4,4'-diazide Organic azides such as chalcone; organic peroxides such as 3,3 ′, 4,4′-tetra (tert-butylperoxycarboxyl) benzophenone; Photochem. Sci. T
echnol. , 2,283 (1987). And specific examples thereof include iron arene complexes, trihalogenomethyl-substituted s-triazines, sulfonium salts, diazonium salts, phosphonium salts, selenonium salts, arsonium salts, iodonium salts and the like. As iodonium salts, Macromolecules,
10, 1307 (1977). Compounds described in, for example, diphenyliodonium, ditolyliodonium,
Phenyl (p-anisyl) iodonium, bis (m-nitrophenyl) iodonium, bis (p-tert-butylphenyl) iodonium, bis (p-chlorophenyl)
Chlorides, bromides, iodonium chlorides such as iodonium, borofluoride salts, hexafluorophosphate salts, hexafluoroarsenate salts, aromatic sulfonate salts, and diphenylphenacylsulfonium (n-
Butyl) triphenyl borate and the like.

Further, the thermal polymerization initiator (D) of the present invention which generates a cationic species by heat is a so-called thermal polymerization initiator which does not show activity under normal conditions of normal temperature and normal pressure and generates a starting species by external stimulus heat. If it is a latent thermal polymerization initiator and is a compound that can be cationically polymerized, different types of epoxy compounds, or different types of polymerization such as epoxy and vinyl ether compounds can also be used. Specifically, tetrafluoroborate of dialkyl allyl sulfoniums, cycloalkyl allyl sulfoniums, alkyl diaryl sulfonium salts, dialkyl aryl sulfoniums, triaryl sulfoniums, benzyl pyridiniums, benzyl ammoniums, benzyl triaryl phosphoniums Salt, hexafluorophosphate salt, hexafluroarsenate salt, tetrafluoroantimonate salt, etc.
The following compounds can be exemplified, but not limited thereto.

[0036]

Embedded image

(Wherein R ₁ and R ₂ are the same or different and are substituted or unsubstituted aliphatic groups, and R ₁ and R ₂ may form a ring. A represents a group represented by the general formulas [I] and [II]) It is a group to be performed.

[0038]

Embedded image

[0039] (R _a to R _d represents a hydrogen atom or a substituted or unsubstituted aliphatic group, at least one of R _a to R _d is an unsubstituted aliphatic group. The, R _e ~ R _g
Is a substituted or unsubstituted aliphatic group. ) R ₃ is one selected from a hydroxyl group, a methoxy group, an ethoxy group, a tert-butoxy group, a methoxycarbonyl group, an acetoxy group, a benzyloxy group, a benzoyl group and a dimethylamino group. R _4, R ₅ represents independently a hydrogen atom, a halogen atom, or an alkyl group of C ₁ -C _4. R ₆ and R ₈ are any of a hydrogen atom, a methyl group, a methoxy group and a halogen atom, and R ₇ is a C ₁ -C ₄
Represents any one of the above alkyl groups. C ₉ is any one of a hydrogen atom, a cyano group, and a nitro group. R _{10 to} R ₁₂ represent an alkyl group, an alkenyl group (which may be substituted with a hydroxyl group, a carboxyl group, an alkoxy group, a nitro group, a cyano group, an alkanoyloxy group), or a phenyl group (an alkyl group, a halogen atom, a nitro group). Group, a cyano group, an alkoxy group, an amino group, or a dialkylamino group).

Further, a sensitizing dye (E) for sensitizing the photopolymerization initiator (C) which generates radical species by the actinic radiation of the present invention may be added according to the wavelength of the actinic radiation to be recorded. Examples of the sensitizing dye (E) for sensitizing the photopolymerization initiator (C) include organic dyes such as cyanine or merocyanine derivatives, coumarin derivatives, chalcone derivatives, xanthene derivatives, thioxanthene derivatives, azurenium derivatives, squarylium derivatives, and porphyrin derivatives. Compounds can be used, and in addition, "Dye Handbook" (Shin Okawara et al., Edited by Kodansha 1986), "Chemistry of functional dyes" (Shin Okawara et al., Edited by CMC 1981),
"Specially Functional Materials" (CEM1 by Chuzaburo Ikemori and others)
986) are used. It should be noted that the dye and the sensitizer are not limited to these, and exhibit absorption for other visible light.
If the photopolymerization initiator used can be spectrally sensitized, it can be used. These may be used in two or more at any ratio as needed.

The amount of component (B) contained in the composition of the present invention can be in the range of 20 to 200 parts by weight, preferably 30 to 100 parts by weight, per 100 parts by weight of (A). Department. The amount of the photopolymerization initiator of the component (C) is 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the component (A). Further, the thermal polymerization initiator of the component (D) is used in an amount of 0.1 to 20 parts by weight, preferably 0.5 to 1 part by weight, per 100 parts by weight of the component (A).
It is possible to take a range up to zero. When the component (E) is used, the amount is 0.1 parts by weight based on 100 parts by weight of the component (A).
To 5 parts by weight, preferably 0.2 to 0.5 parts by weight. The amount used is limited by the thickness of the photosensitive layer and the optical density of the thickness. That is, it is preferable to use the optical density within a range not exceeding 2.

The photosensitive solution obtained by appropriately selecting these components and mixing them in an arbitrary ratio is coated by 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.

When the photosensitive liquid is applied, it may be diluted with an appropriate solvent if necessary, but in that case, it is necessary to apply the solvent on the 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, since the difference in the refractive index that can be recorded is limited by the manufacturing method and the recording material, the film thickness is small when the difference is large, and is reduced when the difference is small. By increasing the thickness, a light-scattering film can be realized using the composition of the present invention.

The size of the portions having different refractive indices is random and non-regular in order to cause light scattering, but has an average size of 0.1 μm in diameter in order to have necessary scattering properties.
It is appropriately selected within the range of 300 μm 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. However, in order to provide necessary scattering, 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 nmin and monotonically decreases to a maximum value nmax of the refractive index monotonically 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 original 9 opposite to the UV irradiation side, and the pattern of the mask original 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 prepared from random number calculation using a computer into a metal chrome pattern 11 on a glass substrate 10 by a so-called photolithography method. 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, as shown in the figure, the ground glass 10 and the photosensitive material 5 are inclined at a predetermined angle α, so that
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 is an argon ion laser of 351 nm, 364 nm, 514.5 n.
m, 488 nm or 457.9 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 krypton ion 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

Description of “Light Measurement Handbook Asakura Shoten Toshiharu Mitsuda et al., Published November 25, 1994” (p. 26)
6 to p. According to 268), in a speckle pattern in which the density and phase show random values depending on the position, the size of the pattern is inversely proportional to the angle at which the diffusion plate is viewed from the photosensitive material, and the average diameter of the pattern is determined. Is done. 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 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 the speckle pattern in the depth direction is represented by t = 4.0λ (F / D) ² .

From the 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> Bisphenol-based epoxy resin epicoat 1004 (epoxy equivalent: 875-97)
5, Yuka Shell Epoxy Co., Ltd. 100 parts by weight, tripropylene glycol diacrylate (VIS
COAT-310HP (trade name, manufactured by Osaka Organic Chemical Co., Ltd.)
50 parts by weight, 3.0 parts by weight of 1-hydroxycyclohexylphenyl ketone (IRGACURE 184, trade name of Ciba Specialty Chemicals), alkyldiarylsulfonium hexafluoroantimonate (SI-100L, solution type, Sanshin Chemical Industry Co., Ltd.) The mixture was dissolved and dissolved in 3.0 parts by weight of a commercial product name) to obtain a photosensitive solution. The photosensitive liquid was applied to a blue sheet glass (1.1 mm thick, 5 inch square) with a doctor blade so that the film thickness became about 50 μm, and dried to obtain a recording medium.

The recording medium is formed by the optical system shown in FIG.
After exposing (α = 22 °, 20 mJ / cm ² ) from the surface of the recording material through the frosted glass 15 with a light obtained by spreading an argon laser (364 nm) as a light source using a lens, the temperature is increased to 80 ° C.
After heating for 10 minutes, fixing was performed by irradiating the entire surface with a high-pressure mercury lamp. Then, the recording medium was heated at 130 ° C. for 30 minutes, and the cured product was separated from the glass substrate to obtain a light scattering film. The thickness of the obtained film is 70
Micron.

For evaluation, the 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).

[0065]

[Table 1]

Example 2 Bisphenol epoxy resin epicoat 1004 (epoxy equivalent: 875-97)
5, in the same manner as in Example 1 except that a hydrogenated bisphenol-based epoxy resin suntote 5100 (epoxy equivalent: 900-1100, trade name, manufactured by Toto Kasei Co., Ltd.) is used instead of the trade name manufactured by Yuka Shell Epoxy Co., Ltd.) To obtain the produced light scattering film. The thickness of the film obtained was 68 microns. Table 2 shows the results.

[0067]

[Table 2]

Example 3 Bisphenol epoxy resin epicoat 1004 (epoxy equivalent: 875-97)
5. Instead of Yuka Shell Epoxy Co., Ltd.), a phenol novolak epoxy resin epicoat 180
The procedure of Example 1 was repeated, except that S65 (epoxy equivalent: 205-220, trade name of Yuka Shell Epoxy Co., Ltd.) was used, to obtain a produced light-scattering film. The resulting film had a thickness of 78 microns. Table 3 shows the results.

[0069]

[Table 3]

Example 4 Alkyldiarylsulfonium hexafluoroantimonate (SI-100L)
Instead of prenyltetramethylenesulfonium hexafluoroantimonate (Adekaopton CP-7)
Example 1 except for changing to (7, Asahi Denka Kogyo Co., Ltd.)
The same operation as described above was carried out to obtain the produced light-scattering film. The thickness of the film obtained was 60 microns. Table 4 shows the results.

[0071]

[Table 4]

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 resulting film had a thickness of 79 microns. Table 5 shows the results
Shown in

[0073]

[Table 5]

Example 6 Bisphenol epoxy resin epicoat 1004 (epoxy equivalent: 875-97)
5. Same as Example 1 except that bisphenol-based epoxy resin Epicoat 1007 (epoxy equivalent: 1750-2200, trade name, manufactured by Yuka Shell Epoxy Co., Ltd.) is used instead of Yuka Shell Epoxy Co., Ltd. To obtain a produced light-scattering film. The thickness of the film obtained was 69 microns. Table 6 shows the results.

[0075]

[Table 6]

Example 7 2-Hydroxy-2-methyl-1-phenylpropane-2-substituted 1-hydroxycyclohexylphenyl ketone (IRGACURE 184, trade name of Ciba Specialty Chemicals) was used instead of 3.0 parts by weight. ON (DAROCURE 1173, Ciba
A light-scattering film was produced in the same manner as in Example 1, except that 3.0 parts by weight of specialty chemicals (trade name) was used. The thickness of the obtained film is 6
9 microns. Table 7 shows the results.

[0077]

[Table 7]

Example 8 Instead of 3.0 parts by weight of 1-hydroxycyclohexyl phenyl ketone (IRGACURE 184, trade name of Ciba Specialty Chemicals), 4,4′-bis (tert-butylphenyl) iodonium hexane was used. Fluorophosphate 4.0
Parts by weight and 3- (p-dimethylaminophenyl) -1
Using 0.25 parts by weight of-(p-methoxyphenyl) -2-propen-1-one and using a krypton laser (41
A light-scattering film was prepared in the same manner as in Example 1 except that 3 nm) was used, but a light-scattering film was obtained. The thickness of the film obtained was 70 microns. Table 8 shows the results.

[0079]

[Table 8]

[0080]

According to the composition of the present invention, light scattered for light incident at a predetermined angle, and conversely, for light perpendicular to the light, it functions as a transparent film. The 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, when used in a display device or the like. Thus, a light-scattering film having the effects of improving the brightness, fineness, and contrast of a display without causing unnecessary scattering and reducing the blur of a display image can be manufactured.

Further, when light is incident at an incident angle at which light scattering occurs, a film having scattering anisotropy such that the spread of the scattered light differs vertically and horizontally can be produced.
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.

[0082]

[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 dependence of the light scattering film of the present invention.

FIG. 4 is a diagram illustrating anisotropy of light scattering possessed by 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]

 DESCRIPTION OF SYMBOLS 1 ... Light scattering film 2 ... Illumination light incident from a scattering direction 3 ... Illumination light incident from a transmission direction 4 ... Plot of 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 ... Chromium pattern 12 ... Optical fiber 13 ... Laser light source 14 ... Laser light 15 ... Frosted glass 16 ... Beam expander 17 ... Collimator

Continued on the front page F term (reference) 2H042 BA06 BA14 BA20 4J011 AA05 QA02 QA03 QA06 QA08 QA12 QA13 QA23 QA24 SA21 SA51 SA62 SA64 SA78 SA80 SA82 SA83 SA84 SA86 SA87 SA88 UA01 UA02 UA08 XA02 4J030 AD05 AD08 AD08 AD08 EA04 GA06 GA23 GA24 HA02 JA15

Claims (6)

[Claims] At least (A) a compound having cationic polymerizability, (B) a compound having radical polymerizability,
(C) a photopolymerization initiator that generates a radical species by actinic radiation, and (D) a thermal polymerization initiator that generates a cationic species by heat, and (A) a compound having cationic polymerizability; and (B) a radical polymerizable compound. A composition for an anisotropic light-scattering film, characterized in that the compounds having a difference in refractive index. 2. The compound (A) having cationic polymerizability.
Is a bisphenol A type epoxy resin or a brominated bisphenol A type epoxy resin having an epoxy equivalent of 400 to 2200, the composition for an anisotropic light-scattering film according to claim 1. 3. The compound (B) having radical polymerizability.
Has a refractive index lower than that of the compound having cationic polymerizability (A), is liquid at normal temperature and normal pressure, and has a boiling point of 100 at normal pressure.
The composition for an anisotropic light-scattering film according to claim 1, which is a compound having at least one ethylenically unsaturated bond having a temperature of at least 0C. 4. The compound (A) having cationic polymerizability.
The composition for an anisotropic light-scattering film according to claim 1, wherein 20 to 80 parts by weight of the compound having radical polymerizability (B) is mixed with 100 parts by weight. 5. A sensitizing dye (E) for sensitizing a photopolymerization initiator (C) which generates a radical species by the actinic radiation.
The composition for an anisotropic light-scattering film according to claim 1, further comprising: 6. A film produced using the composition for an anisotropic light-scattering film according to claim 1, wherein portions having different refractive indexes are distributed in an irregular shape and thickness inside the film. A light and shade pattern having a high or low refractive index is formed, and portions having different refractive indices are distributed in a layered manner inclining with respect to the thickness direction of the film. An anisotropic scattering film having light scattering and having an incident angle selectivity, which functions as a mere transparent film with respect to light incident at an angle and generates light scattering for light perpendicular to the tilt direction.