JP2002062411A - Composition for anisotropic light scattering film and anisotropic light scattering film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for obtaining an anisotropic scattering film which imparts anisotropy in scattering characteristics (forward or backward scattering and dependence on an incident angle), can easily control even scattering characteristics concerned in longitudinal and horizontal scattering ranges and ensures no change in the color of display light independently of the position of viewing and to provide an anisotropic scattering film. SOLUTION: The composition consists essentially of (A) a compound having at least one cationic polymerizable group in one molecule, (B) a radical polymerizable compound, (C) a photopolymerization initiator which generates a cation species under actinic radiation and (D) a thermal polymerization initiator which generates a cation species by heat. The refractive index of the compound (B) is higher than that of the compound (A).

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 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. 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 property to make it.

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 at least one cationically polymerizable group in a molecule;
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,
(B) The compound having radical polymerizability has a refractive index of (A)
It is higher than a compound having at least one cationically polymerizable group in the molecule.

The composition for an anisotropic light-scattering film according to claim 2 is a compound (C) having the cationically polymerizable group.
Is a compound having at least one compound selected from a compound having an oxirane ring, a compound having an oxetane ring, and a vinyl ether compound.

The composition for an anisotropic light-scattering film according to claim 3 is the compound having radical polymerizability (B).
Is a compound having at least one ethylenically unsaturated bond which is liquid at normal temperature and normal pressure and has a boiling point of 100 ° C. or higher at normal pressure.

The composition for an anisotropic light-scattering film according to claim 4 is characterized in that a sensitizing dye (E) for sensitizing a photopolymerization initiator (D) that generates a radical species by the actinic radiation is added. And

[0016] The composition for an anisotropic light-scattering film according to the fifth aspect is characterized by further comprising a polymer binder (F).

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 dependency 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 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.

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.

The compound (A) having at least one cationically polymerizable group in the molecule used in the composition of the present invention has lower reactivity and lower refractive index than the compound (B) having radical polymerizability. Further, it is desirable that the viscosity be reduced upon heating after exposure. The compound exists as a low-viscosity compound when the compound having radical polymerizability is polymerized, and thus serves as a so-called plasticizer that facilitates the diffusion and transfer of the compound having radical polymerizability. Further, since the compound is cured at the time of heating and fixing, it is present as a polymer in the anisotropic scattering film, so that there is no adverse effect such as thermal deterioration. It can also be improved. In addition, since the refractive index is lower than that of the compound having radical polymerizability, there is no adverse effect on scattering.

Preferred examples of the compound having an oxirane ring include (poly) glycidyl ether, glycidyl acrylate and glycidyl methacrylate of an aliphatic polyhydric alcohol or an alkylene oxide adduct thereof. Representative examples are diglycidyl ether of 1,4-butanediol, diglycidyl ether of 1,6-hexanediol, triglycidyl ether of glycerin, triglycidyl ether of trimethylolpropane, (di, tri, poly) ethylene Glycol diglycidyl ether, (di, tri, poly) propylene glycol diglycidyl ether, and the like.

Other compounds having an oxirane ring include 1,2,5,6-diepoxy-4,7-methanoperhydroindene, 2- (3,4-epoxycyclohexyl) -3 ′, 4′-epoxy -1,3-dioxane-
5-spirocyclohexane, 1,2-ethylenedioxy-bis (3,4-epoxycyclohexylmethane),
4 ', 5'-epoxy-2'-methylcyclohexylmethyl-4,5-epoxy-2-methylcyclohexanecarboxylate, ethylene glycol-bis (3,4-
Epoxy cyclohexanecarboxylate), bis-
(3,4-epoxycyclohexylmethyl) adipate, 1,2,7,8-diepoxyoctane or
3,4-epoxycyclohexylmethyl-3 ', 4'-
An alicyclic epoxy compound having an epoxy group or an epoxycyclohexyl group such as epoxycyclohexanecarboxylate is exemplified.

Compounds having an oxetane ring are preferably trimethylene oxide, 3,3-dimethyloxetane, 3,3-dichloromethyloxetane,
Ethyl-3-hydroxymethyloxetane, 3-ethyl-3- (phenoxymethyl) oxetane, 3-ethyl-
3- (p-tolylmethyl) oxetane, 3-ethyl-3
-(Naphthoxymethyl) oxetane, 3,3'-bis (phenoxymethyl) oxetane, 1,4-bis {[(3-ethyl-3-oxetanyl) methoxy] methyl} benzene and the like.

Preferred examples of the vinyl ether compound include vinyl-2-chloroethyl ether and vinyl-n-
Propyl ether, vinyl-n-butyl ether, vinyl isoamyl ether, vinyl-n-octadecyl ether, triethylene glycol divinyl ether,
4-cyclohexanemethanol divinyl ether, trimethylolmethane trivinyl ether, phenyl vinyl ether, p-tolyl vinyl ether, p-methoxyphenyl vinyl ether, naphthyl vinyl ether, bis (4-vinyloxymethylcyclohexylmethyl) glutarate, bis (4-vinyloxybutyl) isophthalate And the like, but not limited thereto. Further, the refractive index of these compounds needs to be lower than that of the radical polymerizable compound (B).

The radical polymerizable compound (B) used in the composition of the present invention refers to a radical polymerizable compound which is polymerized or cross-linked by actinic radiation in the presence of a polymerization initiator which generates radicals by actinic radiation. Compounds having, for example, at least one ethylenically unsaturated bond in the structural unit, containing a polyfunctional vinyl monomer in addition to a monofunctional vinyl monomer, and a mixture thereof. There may be. Further, the compound is a compound (A) having the above-mentioned cationic polymerizable group.
Must have a higher refractive index.

Specifically, (meth) acrylic acid, itaconic acid, maleic acid, phthalic acid, terephthalic acid, (meth)
High-boiling vinyl monomers such as acrylamide, diacetone acrylamide, and 2-hydroxyethyl (meth) acrylate, and further, aliphatic polyhydroxy compounds, for example, propylene glycol, neopentyl glycol,
1,3-propanediol, 1,4-butanediol,
1,5-pentanediol, 1,6-hexanediol, 1,10-decanediol, trimethylolpropane, pentaerythritol, dipentaerythritol,
Mono, di or poly (meth) acrylates such as sorbitol and mannitol, or ethyl carbitol acrylate, norbornene methanol acrylate, adamantane methanol acrylate, 2-ethylhexyl carbitol acrylate, dicyclopentenyloxyethyl acrylate, phenyl carbitol acrylate , Nonylphenoxyethyl acrylate,
2-hydroxy-3-phenoxypropyl acrylate, ω-hydroxyhexanoyloxyethyl succinate, acryloyloxyethyl phthalate, phenyl acrylate, tribromophenyl acrylate, tribromophenoxyethyl acrylate, 2- (p-chlorophenoxy) ethyl acrylate, 2- (1-naphthyloxy) ethyl acrylate, o-biphenyl acrylate, phenoxyethyl acrylate, isobornyl acrylate, benzyl acrylate, p-bromobenzyl acrylate, lauryl acrylate, neopentyl glycol monoacrylate, neopentyl glycol diacrylate, 4 -Hydroxybutyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, -Acryloyloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy-3-phenoxypropyl acrylate, 2-acryloyloxyethyl hydrogen phthalate, 2-acryloyloxy hydrogen phthalate, 2-acryloyloxypropyl hexahydrohydrogen phthalate, bisphenol A (EO Modified) diacrylate, bisphenol F (EO-modified) diacrylate, and methacrylates corresponding to these acrylates, but are not limited thereto. The refractive index of these compounds needs to be higher than that of the compound (A) having a cationically polymerizable group.

(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, 2,2 ′
-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'-diazidochalcone Organic azides, organic peroxides such as 3,3 ', 4,4'-tetra (tert-butylperoxycarboxyl) benzophenone, and the like. 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, but generates a starting species by heat as an external stimulus. 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.

[0037]

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 the general formulas [I] and [II]) It is a group to be performed.

[0039]

Embedded image

(Ra to Rd are a hydrogen atom or a substituted or unsubstituted aliphatic group, and at least one of Ra to Rd is an unsubstituted aliphatic group. Re to Rg
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 10 to 250 parts by weight, preferably 20 to 200 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). Component (D)
The amount of the thermal polymerization initiator can range from 0.1 to 20 parts by weight, preferably from 0.5 to 10 based on 100 parts by weight of the component (A). The amount of component (E) when used can range from 0.05 to 5 parts by weight, preferably from 0.1 to 0.5 parts by weight, per 100 parts by weight of (A). is there. 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 composition for an anisotropic light-scattering film according to claim 1 may further comprise a known polymer binder, if necessary.
Various additives such as a silane coupling agent, a plasticizer, a polymerization inhibitor, a chain transfer agent, an antioxidant, a leveling agent, and an antifoaming agent may be added. The polymer binder (F) is used for improving the film forming property, the uniformity of the film thickness, the storage stability and the like of the composition for an anisotropic light scattering film. The polymer binder (F) may be any aliphatic binder that can be mixed with a photopolymerizable compound or a photopolymerization initiator and does not hinder the difference in the refractive index of the material. Specific examples thereof include chlorinated polyethylene and polymethyl. Methacrylate, copolymers of methyl methacrylate and other alkyl (meth) acrylates, copolymers of vinyl chloride and acrylonitrile, polyvinyl acetate, polyvinyl formal, polyvinyl butyral, ethyl cellulose, acetyl cellulose, and the like. It is not limited. These may be used alone or in combination of two or more.

The photosensitive solution obtained by appropriately selecting these components and 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, but in that case, it is necessary to apply the photosensitive liquid on a substrate and then dry it. Examples of the solvent include dichloromethane, chloroform, acetone, 2-butanone, cyclohexanone, ethyl acetate, methanol, ethanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-ethoxyethyl acetate, and 2-butoxyethyl acetate. , 2
-Methoxyethyl ether, 2-ethoxyethyl ether, 2- (2-ethoxyethoxy) ethanol, 2-
(2-butoxyethoxy) ethanol, 2- (2-ethoxyethoxy) ethyl acetate, 2- (2-butoxyethoxy) ethyl acetate, tetrahydrofuran,
1,4-dioxane and the like can be mentioned.

Further, since the refraction index that can be recorded is limited by the manufacturing method and the recording material, the film thickness is small when the refraction index is large, and is reduced when the refraction index 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. 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. However, in order to provide necessary scattering, the average refractive index of the entire film is required. Is assumed to be <n>, the probability distribution exhibits a normal distribution centered on <n>. Alternatively, the refractive index n may be distributed in accordance with 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 or a monotonically increasing probability distribution.

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 arranged 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 and irradiated on the photosensitive material 5. 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 produced by random number calculation using a computer into a metal chrome 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 diagram 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,
Among the wavelengths of 413 nm, 364 nm and 351 nm, they can be appropriately selected and used according to the sensitivity of the photosensitive material. A laser light source having good coherence other than the argon ion and krypton ion lasers 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

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 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 optimum scattering properties.

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. Actually, portions having different refractive indices of various sizes large and small with respect to these sizes 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 polyethylene glycol diglycidyl ether (Denacol EX-861, trade name of Nagase Kasei Kogyo Co., Ltd.), phenoxyethyl acrylate (VISCOAT # 192, trade name of Osaka Organic Chemical Co., Ltd.) ) 50 parts by weight, 3.0 parts by weight of 1-hydroxycyclohexyl phenyl ketone (IRGACURE 184, trade name of Ciba Specialty Chemicals), alkyldiarylsulfonium hexafluoroantimonate (SI-100L, solution type, Sanshin Chemical Industry) A solution prepared by mixing and dissolving 3.0 parts by weight (trade name, manufactured by Co., Ltd.) 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 so that the film thickness becomes about 30 microns, and dried to obtain a recording medium.

The recording medium was converted by the optical system shown in FIG.
Exposure (α = 22 °, 10 mJ / cm ² ) from the surface of the recording material through frosted glass 15 with light obtained by spreading an argon laser (364 nm) using a lens as a light source, heating at 85 ° C. for 5 minutes, and then using a high-pressure mercury lamp The recording medium was fixed by irradiating the entire surface of the recording medium. Further, the recording medium was heated at 130 ° C. for 3 hours.
After heating for 0 minutes, the cured product was peeled from the glass substrate to obtain a light-scattering film. 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 82 82 81 72 33 21 14

Example 2 Instead of 100 parts by weight of polyethylene glycol diglycidyl ether, 50 parts by weight of sorbitol polyglycidyl ether (Denacol EX-614, trade name of Nagase Kasei Kogyo Co., Ltd.) and 3,4-epoxycyclohexylmethyl -3 ', 4'-epoxycyclohexanecarboxylate (Araldite CY17
9, Nippon Specialty Chemicals Co., Ltd. product name) 5
The same operation as in Example 1 was carried out except that the mixed system was 0 parts by weight to obtain a produced light-scattering film. The thickness of the film obtained was 25 microns. Table 2 shows the results.

[Table 2] Measurement angle (°) 0 10 20 22 25 30 40 Transmittance 80 79 77 65 29 19 19 17

Example 3 Instead of 100 parts by weight of polyethylene glycol diglycidyl ether, 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate (Araldite CY17
9, Nippon Specialty Chemicals Co., Ltd. product name) 5
0 parts by weight and 50 parts by weight of 3-ethyl-3-hydroxymethyloxetane (OXT-101, trade name, manufactured by Toagosei Co., Ltd.) except that 100 parts by weight of polyvinyl acetate was added as a polymer binder. Was operated in the same manner as in Example 1 to obtain a produced light-scattering film. The resulting film had a thickness of 28 microns. Table 3 shows the results.

[Table 3] Measurement angle (°) 0 10 20 22 25 30 40 Transmittance 86 85 82 72 37 17 15

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 obtained film was 30 microns. Table 4 shows the results.

[Table 4] Measurement angle (°) 0 10 20 22 25 30 40 Transmittance 83 81 80 70 31 17 14

Example 5 An operation was performed in the same manner as in Example 1 except that bisphenol A (EO-modified) diacrylate (Aronix M-210, trade name of Toagosei Co., Ltd.) was used instead of phenoxyethyl acrylate. Thus, the produced light-scattering film was obtained. The thickness of the resulting film was 29 microns. Table 5 shows the results.

[Table 5] Measurement angle (°) 0 10 20 22 25 30 40 Transmittance 78 78 77 55 22 16 11

<Example 6> 1-Hydroxycyclohexyl phenyl ketone (IRGACURE 184, trade name of Ciba Specialty Chemicals) was replaced with 3.0 parts by weight of 2-hydroxy-2-methyl-1-phenylpropane-2- 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 2
It was 8 microns. Table 6 shows the results.

[Table 6] Measurement angle (°) 0 10 20 22 25 30 40 Transmittance 80 80 79 71 32 19 15

Example 7 Instead of 3.0 parts by weight of 1-hydroxycyclohexylphenyl ketone (IRGACURE 184, trade name of Ciba Specialty Chemicals), 4,4′-bis (tert-butylphenyl) iodonium hexa 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
3 nm) to obtain a light-scattering film. The thickness of the obtained film was 30 microns. Table 7 shows the results.

[Table 7] Measurement angle (°) 0 10 20 22 25 30 40 Transmittance 83 82 80 73 32 18 16

<Comparative Example 1> Instead of phenoxyethyl acrylate, tripropylene glycol diacrylate (VISCOAT-310HP, manufactured by Osaka Organic Chemical Co., Ltd.)
An operation was performed in the same manner as in Example 1 except that (trade name) was used to prepare a light-scattering film, but no scattering property was exhibited. The thickness of the obtained film was 30 microns.

<Comparative Example 2> The procedure of Example 1 was repeated, except that bisphenol A type epoxy resin (Epicoat 1007, trade name of Yuka Shell Epoxy Co., Ltd.) was used instead of polyethylene glycol diglycidyl ether. An attempt was made to produce a scattering film, but no scattering property was exhibited. The thickness of the obtained film was 30 microns.

[0081]

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, 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.

[0083]

[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 ... Chrome pattern 12 ... Optical fiber 13 ... Laser light source 14 ... Laser light 15 ... Frosted glass 16 ... Beam expander 17 ... Collimator

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02F 1/1335 G02F 1/1335 4J100 G03F 7/004 501 G03F 7/004 501 7/027 501 501/0727 501 7/028 7/028 F-term (reference) 2H025 AA02 AB14 AB20 AC01 AD01 BC13 BC23 BC42 BD03 CA00 CA41 CB00 CC20 2H042 BA01 BA14 BA15 BA20 2H049 CA16 CA22 CA28 2H091 FA16Z LA30 4J011 QA02 QA06 QA08 SAA32 SAA25 SA80 SA82 SA83 SA84 SA86 UA01 VA01 WA01 4J100 AE02P AE05P AE09P AE70P AE76P AJ02Q AJ08Q AJ09Q AL05Q AL08Q AL09Q AL62Q AL63Q AM15Q AM21Q BA02Q BA03Q BA05P BA08P BA12Q BA16Q BA20PBC BC01BC04PBC

Claims (6)

[Claims] At least (A) a compound having at least one cationically polymerizable group in a molecule, (B) a compound having radical polymerizability, and (C) a photopolymerization initiator for generating radical species by actinic radiation. And (D) a thermal polymerization initiator that generates cationic species by heat,
(B) The compound having radical polymerizability has a refractive index of (A)
A composition for an anisotropic light-scattering film, wherein the composition is higher than a compound having at least one cationically polymerizable group in a molecule. 2. The compound (A) having at least one cationically polymerizable group in the molecule comprises at least one compound selected from a compound having an oxirane ring, a compound having an oxetane ring, and a vinyl ether compound. The composition for an anisotropic light-scattering film according to claim 1, wherein 3. The compound (B) having radical polymerizability.
Is a compound having at least one ethylenically unsaturated bond having a boiling point of 100 ° C. or higher at normal temperature and normal pressure and a normal pressure and normal pressure, for an anisotropic light-scattering film according to claim 1. Composition. 4. A sensitizing dye (E) for sensitizing a photopolymerization initiator (D) which generates a radical species by the actinic radiation.
The composition for an anisotropic light-scattering film according to claim 1, further comprising: 5. The composition for an anisotropic light-scattering film according to claim 1, further comprising a polymer binder (F). 6. A film produced using the composition for an anisotropic light-scattering film according to any one of claims 1 to 5, 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 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. An anisotropic scattering film having a light scattering property and an incident angle selectivity that 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.