JP2000297113A - Composition for colorless light scattering film - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide anisotropic scattering characteristics (dependence on forward or backward and incident angle) to easily control even the scattering characteristics related to the vertical and horizontal scattering ranges. And a composition for obtaining an anisotropic scatterer in which the color of display light does not change depending on the observation position. An incident angle is selected in a light-scattering manner such that light is scattered with respect to light incident at an angle along the tilt direction, and the light perpendicular to the tilt direction functions as a mere transparent film. A composition for forming a light-scattering film having photosensitivity, a plurality of compounds having photopolymerizability and having different refractive indices and different reactivities, and a photoinitiator that generates a polymerization initiation species by actinic radiation. A colorless light-scattering film composition comprising a sensitizing dye for sensitizing an initiator and an ammonium borate represented by the general formula (I). Embedded image

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.

[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.

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 such as a sandblaster treatment, or chemically matted by a 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 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 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. 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.

[0111]

According to the anisotropic scattering film obtained from the present invention, a portion having a different refractive index is distributed in an irregular shape and thickness inside the film, so that the light and shade having a high and low refractive index can be obtained. Patterns are formed, and by optimizing the size, shape, and distribution of the portions with different refractive indexes along the vertical and horizontal directions on the film surface and the thickness direction of the film, the scattering characteristics depending on the incident angle The present invention provides a change, eliminates light scattering in an unnecessary direction, and scatters light only in a necessary direction (range). The present invention provides compounds having different refractive indices and different reactivities. Consisting of
Further, the present invention provides a composition for an anisotropic scattering film, characterized in that the produced film is almost colorless.

In the composition for a colorless light-scattering film according to the first aspect, a portion having a different refractive index is distributed in an irregular shape and thickness, thereby forming a light and shade pattern having a high and low refractive index. And a light scattering film having a structure in which the portions having different refractive indices are distributed in layers in a manner inclined with respect to the thickness direction of the film, and for light incident at an angle along the inclined direction. Is a composition that forms a light-scattering film that has light-scattering properties and is incident angle-selective, such that light scattering occurs and functions as a mere transparent film for light perpendicular to the tilt direction. A plurality of compounds having different refractive indices and different reactivities, a photoinitiator for generating a polymerization initiation species by actinic radiation, a sensitizing dye for sensitizing the initiator, and a compound represented by the general formula (I): Ammonium borate represented When characterized in that it consists of a.

[0013]

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(Wherein R ₁ , R ₂ , R ₃ and R ₄ are each independently an alkyl group, an aryl group, an allyl group, an alkoxy group, an alkenyl group, an alkynyl group, a silyl group, a heterocyclic group,
Y ⁺ is a quaternary ammonium cation or a halogen atom, 4
Quaternary pyridinium cation, quaternary quinolinium cation,
It represents a phosphonium cation, a sulfonium cation, an oxosulfonium cation, an iodonium cation or a metal cation. )

The composition for a colorless light-scattering film according to claim 2 is characterized in that the photoinitiator is a diaryliodonium salt.

According to a third aspect of the present invention, in the composition for a colorless light-scattering film according to the first or second aspect, the sensitizing dye has a molecular structure conjugated to a dialkylamino group,
It is a 3-substituted coumarin compound represented by the following general formula (II).

[0017]

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(Wherein R ₅ , R ₆ , R ₇ and R ₈ are hydrogen, an alkyl group, an alkoxy group, an alkylamino group, a dialkylamino group, a cyano group, or a condensed or heterocyclic ring system of two) Z represents an aryl group, a heterocyclic group, or a group represented by the following general formula (III).
R ₉ represents an alkyl group, an alkoxy group, an aryl group, an aryloxy group, or a heterocyclic group. )

[0019]

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According to a fourth aspect of the present invention, there is provided the colorless light-scattering film composition according to the first or second aspect, wherein the dye has a molecular structure conjugated to a dialkylamino group and is capable of spectrally sensitizing a photoinitiator. Is a p-amino unsaturated ketone compound represented by the following general formula (IV).

[0021]

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(Wherein m and n are each 0 or 1, and R ₁₀ and R ₁₁ are a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, or CH ₂ COOR ₁₅ [where R ₁₅ is a hydrogen atom or a carbon atom. Represents 1 to 5 alkyl groups, alkali metal, ammonium, amine], or C ₂ H ₄ CF ₃ , C _{2
H 4 I, C 2 H 4} Br, C 2 H 4 Cl, C 2 H 4 F, C 2 H 4 C
N, C ₂ H ₄ NO ₂ are shown. R ₈ is a methylidine group or R ₁₃
Bonded to an alkylene having 1 to 5 carbon atoms which may form a ring together with the carbonyl group and - ylidine group, R ₁₃
Is a carbon atom, a substituted or unsubstituted phenyl group, or a group which forms indanone or tetralone with R ₁₂ and a carbonyl group, a group represented by the general formula (V) [where R
₁₆ , R ₁₇ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, or CH ₂ COOR ₁₈ [provided that R ₁₈ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, an alkali metal, ammonium, an amine, Or C ₂ H ₄ CF ₃ , C ₂ H ₄
I, C ₂ H ₄ Br, C ₂ H ₄ Cl, C ₂ H ₄ F, C ₂ H ₄ CN,
C ₂ H ₄ NO ₂ . ]. )

[0023]

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[0024]

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.
It is explanatory drawing which shows the light-scattering film 1 in which the density pattern which distributed in thickness and the refractive index was high and low (it represents with black and white in the figure) was formed, the left is a top view, and the right is a cross section. FIG.

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), if the light incident on the portion is scattered and emitted, the light emitted from each portion is scattered. 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 degrees in the figure), and conversely, the incident angle is symmetric (−60 degrees in the figure). The haze value with respect to the light of (from 0 ° to 0 °) is 20% or less, which indicates the scattering angle dependence in the present specification.

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 reflected. 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 is deteriorated. On the contrary, if the difference is too large, light scattering occurs regardless of the angle of the incident light. It becomes difficult to have dependencies.

The compound having a different reactivity used in the composition of the present invention is a compound having a cationic polymerizability which is polymerized or cross-linked by actinic radiation in the presence of an initiator generating a cation by actinic radiation, for example, Epoxy compounds, cyclic ether compounds, cyclic lactone compounds, cyclic acetal compounds, cyclic thioether compounds, spiroorthoester compounds, vinyl compounds, etc.
Compounds having a radical polymerizability that polymerize or cross-link by irradiation with actinic radiation in the presence of one or a mixture of two or more, or an initiator that generates radicals by actinic radiation, for example, at least one compound in a molecule Or a mixture of two or more compounds having a polymerizable ethylenic double bond. Of these, any combination may be used as long as the reactivity and the refractive index are different, or a combination of at least one of them and a compound having no reactive group may be used.

Among such compounds having cationic polymerizability, compounds having at least one epoxy group in one molecule are preferred, 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 products of glycidyl ether produced by the reaction of the above bisphenol A or its alkylene oxide adduct 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 from 400, except for epoxy compounds formed by the condensation reaction of various phenol compounds such as volak, o-cresol novolak and p-alkylphenol novolak with epichlorohydrin. 1000 is preferred,
If it is smaller than this, it becomes a liquid, and it cannot be obtained as a film unless a curing treatment by a pretreatment is performed, and uniform coating cannot be performed. If the molecular weight is larger than this range, no characteristics can be obtained.

Specific examples of the compound having radical polymerizability include high-boiling vinyl monomers such as (meth) acrylic acid, itaconic acid, maleic acid, (meth) acrylamide, diacetone acrylamide, and 2-hydroxyethyl (meth) acrylate. And aliphatic polyhydroxy compounds such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, neopentyl glycol, 1,3-propanediol, 1,4-butanediol, Di- or poly (meth) acrylic acid such as 1,5-pentanediol, 1,6-hexanediol, 1,10-decanediol, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitol and mannitol Ethers, etc. While not limited thereto.

The compound having no polymerizable ethylenic double bond is a compound having no polymerizable ethylenic double bond such as acryloyl group, methacryloyl group, vinyl group or allyl group in the molecule. Say.

Examples of such compounds include polystyrene, polymethyl methacrylate or copolymers of various acrylates and methacrylates, polyethylene oxide, polyvinyl pyrrolidone, polyvinyl acetate, polyvinyl alcohol, nylon, cellulose acetate, and cellulose. Acetate succinate, cellulose esters of cellulose acetate butyrate, and cellulose ethers such as methyl cellulose and ethyl cellulose, and polyvinyl butyral and oligomers and polymers such as polyvinyl acetal such as polyvinyl formal can be mentioned. Absent. The plurality of compounds having photopolymerizability and having different refractive indices and different reactivities used in the present invention, the greater the difference between the refractive indices, the greater the degree of light scattering, the so-called haze ratio. Generally, it is preferable that the refractive index difference is 0.01 or more, more preferably 0.05 or more.

The photoinitiator system for generating a radical species or a cationic species by actinic radiation used in the composition of the present invention is described in J. Am. Photochem. Sci. T
echnol. , 2,283 (1987). Compounds, specifically iron arene complex, trihalogenomethyl-substituted s-triazine, sulfonium salt, diazonium salt, phosphonium salt, selenonium salt, arsonium salt, iodonium salt and the like, and also as iodonium salt Is Macromolecules, 1
0 , 1307 (1977). Compounds described in, for example,
Chlorides and bromides of iodonium such as diphenyliodonium, ditolyliodonium, phenyl (p-anisyl) iodonium, bis (m-nitrophenyl) iodonium, bis (p-tert-butylphenyl) iodonium and bis (p-chlorophenyl) iodonium; Alternatively, a borofluoride salt, a hexafluorophosphate salt, a hexafluoroarsenate salt, an aromatic sulfonate, and the like can be given.

The ammonium borate represented by the general formula (I) used in the present invention,

[0044]

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(Wherein R ₁ , R ₂ , R ₃ and R ₄ each independently represent an alkyl group, an aryl group, an allyl group, an alkoxy group, an alkenyl group, an alkynyl group, a silyl group, a heterocyclic group,
Y ⁺ is a quaternary ammonium cation or a halogen atom, 4
Quaternary pyridinium cation, quaternary quinolinium cation,
It represents a phosphonium cation, a sulfonium cation, an oxosulfonium cation, an iodonium cation or a metal cation. )

Specific examples of the anion portion include n-butyltriphenylborate, n-octyltriphenylborate, n-dodecyltriphenylborate, sec-butyltriphenylborate, t-butyltriphenylborate, and benzyltriphenylborate. N-butyl trianisyl borate, n-octyl trianisyl borate, n-dodecyl trianisyl borate, n-butyl tri (4-tolyl) borate, n-butyl tri (2-tolyl) borate, n-butyl tri (4-t- Butylphenyl) borate, n-butyltri (4-fluoro-2-methylphenyl) borate, n-butyltri (4-fluorophenyl) borate, n-butyltrinaphthylborate, triphenylsilyltriphenylborate, diphenylmethylsilyl Liphenyl borate, dimethylphenylsilyl triphenyl borate, trimethylsilyl triphenyl borate, tetra-n-butyl borate, di-n-butyl diphenyl borate, tetrabenzyl borate, and the like, but are not limited thereto. .

Specific examples of the cation moiety include tetramethylammonium, tetraethylammonium, tetra-n-butylammonium, tetraoctylammonium, methylquinolinium, ethylquinolinium, methylpyridinium, ethylpyridinium and tetramethylphosphonium. , Tetra-n-butylphosphonium, trimethylsulfonium, triphenylsulfonium, trimethylsulfoxonium, diphenyliodonium, di (4-t-butylphenyl) iodonium, lithium cation, sodium cation, and the like, but are not limited thereto. It is not something to be done. These anion part and cation part can be used in the present invention in any combination.

Further, as a sensitizing dye for sensitizing the photoinitiator of the present invention, a 3-substituted coumarin compound represented by the general formula (II):

[0049]

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(Wherein R ₅ , R ₆ , R ₇ and R ₈ are hydrogen, an alkyl group, an alkoxy group, an alkylamino group, a dialkylamino group, a cyano group, or a condensed or heterocyclic ring system of two) Z represents an aryl group, a heterocyclic group, or a group represented by the following general formula (III).
R ₉ represents an alkyl group, an alkoxy group, an aryl group, an aryloxy group, or a heterocyclic group. )

[0051]

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Specifically, 7-diethylamino-3- (2
-Benzothiazyl) -coumarin, 7-diethylamino-
3- (2-benzimidazolyl) -coumarin, 7-diethylamino-3-benzoylcoumarin, 7-diethylamino-3-thienoylcoumarin, 7-diethylamino-
3,3′-carbonylbiscoumarin, 3,3′-carbonylbis (7-diethylaminocoumarin), 9,9′-
Carbonyl bis (1,2,4,5-tetrahydro-3
H, 6H, 10H [I] benzopyrano [9,9a, 1-
gh] quinolazin-10-one) and the like, but are not limited thereto. Methods for synthesizing these compounds are described in Chemical Reviews
361 (1945) and Tetrahedron
38 (9) 1203-1211 (1982).

Further, as the p-aminophenyl unsaturated ketone compound represented by the general formula (IV),

[0054]

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Wherein m and n are each 0 or 1, and R ₁₀ and R ₁₁ are a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, or CH ₂ COOR _15, wherein R ₁₅ is a hydrogen atom or a carbon atom. Represents an alkyl group having 1 to 5 alkyl groups, an alkali metal, ammonium, an amine, or C ₂ H ₄ CF ₃ ,
C ₂ H ₄ I, C ₂ H ₄ Br, C ₂ H ₄ Cl, C ₂ H ₄ F, C ₂ H ₄
CN and C ₂ H ₄ NO ₂ are shown. R ₁₃ is a methylidyne group or an alkylene-iridine group having 1 to 5 carbon atoms which can form a ring together with a carbonyl group by bonding to R ₁₃ ;
R ₁₃ is a carbon atom, a substituted or unsubstituted phenyl group, or a group that forms indanone or tetralone with R ₁₂ and a carbonyl group, a group represented by the following general formula (V), provided that R ₁₆ and R ₁₇ are hydrogen atoms Or 1 to 5 carbon atoms
Or CH ₂ COOR ₁₁ wherein R ₁₁ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, an alkali metal, ammonium, an amine, or C ₂ H ₄ C
F ₃ , C ₂ H ₄ I, C ₂ H ₄ Br, C ₂ H ₄ Cl, C ₂ H ₄ F,
C ₂ H ₄ CN and C ₂ H ₄ NO ₂ . Indicates｝. )

[0056]

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Specifically, 2,5-bis (4'-diethylaminobenzylidene) cyclopentanone, 2,5-bis (4'-dimethylaminobenzylidene) cyclopentanone, 2,6-bis (4'-diethylamino) Benzylidene) cyclohexanone, 2,6-bis (4′-dimethylaminobenzylidene) cyclohexanone, 2,5-bis (4′-dimethylaminocinnamylidene) cyclopentanone, 2,6-bis (4′-dimethylaminocinna) Mylidene) cyclohexanone, 1,3-bis (4'-dimethylaminobenzylidene) acetone, 2- (4'-diethylaminobenzylidene) -1-indanone, 2- (9 '
-Durolylidene) -1-indanone, 2- (4'-diethylaminobenzylidene) -1-tetralone, 4'-
Diethylamino-2'-methylbenzylidene-acetophenone, 2,5-bis (4'-N-ethyl-N-carbomethoxymethylaminobenzylidene) cyclopentanone, and its sodium salt, 2,5-bis (4'-N
-Methyl-N-cyanoethylaminobenzylidene) cyclopentanone, 2,5-bis (4'-N-ethyl-N-
Chloroethylaminocinnamylidene) cyclopentanone, 2,6-bis (4′-N-cyanoethylaminobenzylidene) cyclohexanone, 2- (4′-N-ethyl-N-carboxymethylaminobenzylidene) -1-indanone, 2- (4'-N-ethyl-N-carboxymethylaminobenzylidene) -1-tetralone, 2-
Examples thereof include (4′-ethyl-N-cyanoethylaminobenzylidene) -1-indanone, and a sodium salt thereof, but are not limited thereto.

These sensitizing dyes can be selected according to the purpose of use so as to match the wavelength of the radiation serving as a light source, and depending on the application, two or more kinds may be used in combination.

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.

When the photosensitive liquid is applied, it may be diluted with an appropriate solvent if necessary, but in that case, drying is required after application on the substrate. 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, and 2-methoxyethyl acetate. 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. 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 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.

The means for producing the light scattering film of the present invention will be described below. 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.

A 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 to 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 prepared from 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 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 514.5 nm, 488 nm or 45 nm.
Among the wavelengths of 7.9 nm, they 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 Mitsuyuki and others, published on 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 frosted glass, and the distance F between the frosted glass and the photosensitive material are:
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 .

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, and in fact, portions having different refractive indices of various sizes large and small with respect to these sizes are distributed obliquely on the surface and 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 and comparative examples for clarifying the features of the present invention.

<Example 1> Bisphenol 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, 7.5 parts by weight of 4,4'-bis (tert-butylphenyl) iodonium hexafluorophosphate, 0.5 part by weight of tetrabutylammonium butyltriphenylborate (P3B, manufactured by Showa Denko KK), A photosensitive solution was prepared by mixing and dissolving 0.1 part by weight of 3,3′-carbonylbis (7-diethylaminocoumarin) in 100 parts by weight of 2-butanone. The photosensitive solution was applied to blue plate glass (1.1 mm thick, 5 inch square) with a thickness of about 50 μm.
Was applied with a doctor blade and dried to obtain a recording medium.

The recording medium was exposed from the surface of the recording material (α = 22) with the optical system shown in FIG. 6 using a light obtained by spreading an argon laser (488 nm) as a light source using a lens and using a glass glass 15. #, After 40mJ / cm ² ), 80
C. for 1 minute, and 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 obtained film was 70 μm.

For evaluation, transmittance (wavelength range: 400 to 600 nm) was measured at each angle with a spectrophotometer manufactured by Shimadzu Corporation. Table 1 shows the results (average transmittance of all wavelengths). The resulting film had an average transmittance of 85% at 400 to 500 nm and was almost colorless.

[0082]

[Table 1]

Example 2 Tetrabutylammonium butyltriphenylborate (P3B, manufactured by Showa Denko KK)
Was used in the same manner as in Example 1 except that tetrabutylammonium butyl trinaphthyl borate (N3B, manufactured by Showa Denko KK) was used instead of the above, to obtain a light-scattering film produced. The thickness of the obtained film was 67 μm. Table 2 shows the results. 400 to 5 of the obtained film
The average transmittance at 00 nm was 82%, almost colorless.

[0084]

[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 light-scattering film produced. The thickness of the obtained film was 74 μm. Table 3 shows the results
Shown in The average transmittance of the obtained film at 400 to 500 nm was 86%, and it was almost colorless.

[0086]

[Table 3]

Example 4 Instead of 3,3′-carbonylbis (7-diethylaminocoumarin), 2-N,
Instead of N-dimethylaminobenzylidene) -p-methoxyacetophenone, an argon laser (488) was used as a light source.
nm) was replaced with a krypton laser (413 nm) to operate in the same manner as in Example 1 to obtain a light-scattering film. The thickness of the obtained film is 7
It was 1 μm. Table 4 shows the results. The average transmittance of the obtained film at 400 to 500 nm is 88%,
It was almost colorless.

[0088]

[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 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 obtained film was 75 μm. Table 5 shows the results. The average transmittance of the obtained film at 400 to 500 nm was 82%, and it was almost colorless.

[0090]

[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 obtained film was 81 μm. Table 6 shows the results. The resulting film had an average transmittance of 83% at 400 to 500 nm and was almost colorless.

[0092]

[Table 6]

Example 7 Bisphenol epoxy resin (Epicoat 1004, epoxy equivalent: 875-97)
5, 60 parts by weight of bisphenol-based epoxy resin (Epicoat 1004, epoxy equivalent: 875-975, trade name of Yuka Shell Epoxy Co.) and bromination instead of 100 parts by weight of Yuka Shell Epoxy Co., Ltd. A light-scattering film was obtained in the same manner as in Example 1, except that 40 parts of a bisphenol-based epoxy resin (Araldite 8049SP, epoxy equivalent: 450-490, trade name of Ciba-Geigy Corporation) was used. . The thickness of the obtained film was 77 μm. Table 7 shows the results.
The average transmittance of the obtained film at 400 to 500 nm was 82%, and it was almost colorless.

[0094]

[Table 7]

Comparative Example 1 A light-scattering film was prepared in the same manner as in Example 1 except that tetrabutylammoniumbutyltriphenylborate (P3B, manufactured by Showa Denko KK) was not used. However, no scattering property was exhibited. The thickness of the obtained film was 70 μm.

Comparative Example 2 Without using the tetrabutylammonium butyltriphenylborate of Example 1 (P3B, manufactured by Showa Denko KK), 3,3′-carbonylbis (7-
A light-scattering film (thickness of the obtained film was 70 μm) was prepared in the same manner as in Example 1 except that the amount of diethylaminocoumarin was increased to 0.25 parts by weight. Scattering appeared, but 400
The average transmittance at で 500 nm was 70% and was pale yellow.

[0097]

According to the present invention, light scattering occurs for light incident at a predetermined angle, and conversely, it functions as a transparent film for light perpendicular to the light, thereby reducing light scattering. It has an incident angle selectivity, so that light that needs scattering and light that does not need scattering can be separated by the angle of incidence on the film, and as a result, it is unnecessary when used for display devices etc. It is possible to produce a light-scattering film which has an effect of improving the brightness, fineness and contrast of a display without causing significant scattering and reducing a blur of a display image.

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.

Further, since the amount of sensitizer due to color can be reduced, a light-scattering film made of the composition of the present invention is almost colorless.

[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 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

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) // C08L 63:00 F term (Reference) 2H042 BA02 BA14 BA15 BA20 4F071 AA42 AC07 AC10 AC17 AE06 AF30 AF30Y AF31 AH19 BA02 BB02 BB12 BC01 BC17 4J011 QA02 QA03 QA06 QA08 QA09 QA13 QA22 QA23 QA33 QA40 QB06 QB16 SA75 SA82 SA83 SA85 SA86 SA87 SA88 UA01 UA05 VA01 WA01 WA10 4J015 DA04 DA33

Claims (4)

[Claims] 1. A pattern having a different refractive index is distributed in an irregular shape and thickness to form a light and shade pattern having a high or low refractive index. A light scattering film having a structure that is distributed in a layered manner with respect to the inclination direction, wherein light incident on light incident at an angle along the inclination direction occurs, and is perpendicular to the inclination direction. The composition that forms a light-scattering film that has an incident angle selectivity in light-scattering properties that functions as a mere transparent film with respect to natural light is photopolymerizable and has a difference in the refractive index of each. A plurality of compounds having different properties, a photoinitiator for generating a polymerization initiation species by actinic radiation, a sensitizing dye for sensitizing the initiator, and an ammonium borate salt represented by the general formula (I). Characteristic colorless light scattering Irumu composition. Embedded image (Wherein, R ₁ , R ₂ , R ₃ and R ₄ each independently represent an alkyl group, an aryl group, an allyl group, an alkoxy group, an alkenyl group, an alkynyl group, a silyl group, a heterocyclic ring, a halogen atom, and Y ⁺ Represents a quaternary ammonium cation, a quaternary pyridinium cation, a quaternary quinolinium cation, a phosphonium cation, a sulfonium cation, an oxosulfonium cation, an iodonium cation or a metal cation.) 2. A composition for a colorless light-scattering film, wherein the photoinitiator is a diaryliodonium salt. 3. The method according to claim 1, wherein the sensitizing dye is a 3-substituted coumarin compound represented by the general formula (II) having a molecular structure conjugated to a dialkylamino group. A composition for a colorless light scattering film. Embedded image (Wherein R ₅ , R ₆ , R ₇ and R ₈ are hydrogen, an alkyl group, an alkoxy group, an alkylamino group, a dialkylamino group,
A cyano group or two of them may form a fused ring system or a fused heterocyclic system. Z is an aryl group, a heterocyclic group, or
It represents a group represented by the following general formula (III). R ₉ represents an alkyl group, an alkoxy group, an aryl group, an aryloxy group, or a heterocyclic group. ) 4. A dye having a molecular structure conjugated to a dialkylamino group and capable of spectrally sensitizing a photoinitiator is a p-amino unsaturated ketone compound represented by the following general formula (IV): The composition for a colorless light-scattering film according to claim 1 or 2, wherein: Embedded image (Wherein m and n are each 0 or 1 and R ₁₀ , R ₁₁
Is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, or CH ₂ COOR _15, wherein R ₁₅ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, an alkali metal, ammonium,
An amine,｝, or C ₂ H ₄ CF ₃ , C ₂ H ₄ I, C ₂
H ₄ Br, C ₂ H ₄ Cl, C ₂ H ₄ F, C ₂ H ₄ CN, C ₂ H ₄
NO ₂ is shown. R ₁₃ is alkylene of 1 to 5 carbon atoms which may form a ring together with bonded to a carbonyl group and methylidine group or R ₁₃ - ylidine group, R ₁₃ is a carbon atom, a substituent or unsubstituted phenyl group or, A group forming indanone or tetralone together with R ₁₂ and a carbonyl group, a group represented by the following general formula (V), provided that R ₁₆ ,
R ₁₇ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms,
Or CH ₂ COOR ₁₁ [where R ₁₁ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, an alkali metal, ammonium, an amine], or C ₂ H ₄ CF ₃ , C ₂ H
₄ I, C ₂ H ₄ Br, C ₂ H ₄ Cl, C ₂ H ₄ F, C ₂ H ₄ C
N, C ₂ H ₄ NO ₂ . Indicates｝. )