JP2002267813A - Light diffusion film and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light diffusion film and the manufacturing method with which the transmission efficiency of incident light is high, visual field angle characteristics are excellent, the images of high contrast are provided and the images with quality without roughness are provided. SOLUTION: This light diffusion film 10 is provided with a first light absorption layer 11, a transparent undercoating layer 12 arranged on one side of the first light absorption layer, a plurality of transparent beads 13 whose one part is exposed from the first light absorption layer and other part is buried and fixed to the first light absorption layer 11 and the transparent undercoating layer 12 and a second light absorption layer 1 provided with a non light absorption area 14a in respective areas corresponding to the transparent beads 13 on the side of the transparent undercoating layer 12, where the first light absorption layer 11 is not arranged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light diffusion film and a method for manufacturing the same, and more particularly, to a diffusion film usable for a transmission screen of a rear projection type display device and a liquid crystal display device, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Hitherto, in a projection type display device and a liquid crystal display device, a light diffusion film has been used as a member for diffusing a collimated light beam and securing a wide viewing angle characteristic. U.S. Pat. No. 2,378,252 states that
A diffusion film having a configuration in which an array of transparent beads is fixed on a substrate by an absorption layer is disclosed.

As a light diffusion film for improving the contrast, a light diffusion film having a structure shown in FIG. 6 is exemplified. FIG. 6 is a schematic cross-sectional view showing a configuration of a light diffusion film for improving contrast. In FIG. 6, a light diffusion film 60 is made of a light-transmitting substrate (hereinafter, referred to as a light-transmitting substrate).
It may be referred to as “transparent substrate”. ) 61, a transparent undercoat layer 62, a light absorbing layer 63, and light-transmitting microsphere transparent beads (hereinafter sometimes referred to as “transparent beads”) 64.
And Here, “transparent” means transparent to visible light, and the same applies hereinafter.

[0004] The light diffusion film 60 is provided with a transparent undercoat on the surface of the transparent substrate 61 in order to secure an opening radius (straight line 65) of the light absorbing layer 63 opened by the transparent beads 64 in order to improve light transmittance. It has a layer 62. The light absorbing layer 63 is provided on the surface of the transparent undercoat layer 62 for the purpose of absorbing ambient light and obtaining an image with high contrast.
A part of the transparent beads 64 is exposed from the light absorbing layer 63, and the other parts are the light absorbing layer 63 and the transparent undercoat layer 6.
2 buried and fixed.

[0005] In the light diffusion film 60, the parallel light beam (collimated light) incident from the direction of arrow 66 is refracted by the transparent beads 64 as shown by a chain line 67.
Once converged, the transparent beads 64 and the transparent undercoat layer 6
The light is diffused through the interface between the transparent substrate 61 and the transparent substrate 61. Since the light absorbing layer 63 has a light absorbing property, the light absorbing layer 63 serves as a black mask except for the openings of the transparent beads 64, and ambient light is not reflected and scattered from the observer side by the light diffusion film. Therefore, good contrast can be obtained over a wide viewing angle without a decrease in contrast. In addition, since the transparent undercoat layer 62 has an opening for the transparent beads 64, the transmission efficiency of incident light is good and a bright image can be obtained.

[0006] On the other hand, with the recent improvement in the performance of projection display devices and liquid crystal display devices, the performance required of light diffusion films has been significantly increased. Under these circumstances, there is a strong demand for improving the performance of the obtained image, that is, for providing a high contrast and smooth image quality.

In order to obtain an image having a rough image quality using the above-described conventional light diffusion film, first, it is conceivable to reduce the particle size of the transparent beads in the light diffusion film. However, if the particle size of the transparent beads is reduced, a rough image quality can be obtained.However, it is necessary to reduce the thickness of the light absorbing layer with the reduction in the particle size of the transparent beads. The thickness of the light absorbing layer required to secure the thickness is smaller than the required thickness.

[0008] Further, the thickness of the transparent undercoat layer also causes a reduction in contrast. This reduction in contrast is presumed to be due to the ratio between the opening radius (transparent portion) of the transparent beads and the black mask (black portion), and the total reflection of ambient light in the transparent beads. It is conceivable to reduce the thickness of the transparent undercoat layer in order to prevent such a decrease in contrast.However, if the thickness of the transparent undercoat layer is too small, the holding power to the transparent beads decreases, so that the light absorbing layer is formed. The transparent beads are lost in the step of performing the process.
Further, the lowering of the transparent undercoat layer, which can avoid the loss of the transparent beads, cannot prevent the above-mentioned decrease in contrast. For this reason, there is a need for a method capable of preventing a decrease in contrast while keeping the thickness of the transparent undercoating layer from being able to avoid the loss of transparent beads.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above conventional problems and achieve the following objects. That is, the present invention has high transmission efficiency of incident light,
It is an object of the present invention to provide a light diffusion film capable of providing an image having excellent viewing angle characteristics and a high contrast, and further capable of providing an image having a rough image quality. Furthermore, the present invention provides a light diffusion film that has high transmission efficiency of incident light, has excellent viewing angle characteristics, can provide a high-contrast image, and can further provide an image having a rough image quality. It is an object of the present invention to provide a method capable of efficiently producing the same.

[0010]

Means for solving the above problems are as follows. <1> a first light-absorbing layer, a transparent undercoat layer disposed on one side of the first light-absorbing layer, and a part exposed from the first light-absorbing layer and another part exposed from the first light-absorbing layer. 1. A light-diffusing film comprising: a light-absorbing layer and a plurality of transparent beads embedded and fixed in the transparent undercoat layer, wherein the side of the transparent undercoat layer on which the first light-absorbing layer is not disposed And a second light absorbing layer having a non-light absorbing region in each region corresponding to the plurality of transparent beads.

According to the light diffusion film of the present invention, since the second light absorbing layer having the non-light absorbing area in each area corresponding to the plurality of transparent beads is provided, the area other than the light path exiting from the transparent beads is provided. Has a light absorbing region, so that the light absorbing property can be improved.

<2> The light diffusing film according to <1>, wherein the transparent beads have a volume average particle diameter of 0.5 to 50 μm.

According to the light diffusion film of the above <2>, an image without roughness can be obtained by reducing the volume average particle diameter of the transparent beads.

<3> The light diffusing film according to <1> or <2>, wherein the second light absorbing layer is made of a positive photosensitive coloring material.

According to the light diffusing film of the above <3>, by using a positive photosensitive coloring material for the second light absorbing layer,
A non-light-absorbing region can be formed in the light path exiting from the transparent beads.

<4> The first light absorption layer is a light diffusion film according to any one of <1> to <3>, wherein the first light absorption layer is made of a negative photosensitive coloring material or a black pigment.

According to the light diffusing film of <4>, the first light absorbing layer is made of a negative photosensitive coloring material or a material in which a black pigment is dispersed in a photo-curable resin, thereby exposing and curing. Thus, a light absorption region can be formed.

<5> The light diffusion film according to any one of <1> to <4>, further including a transparent adhesive layer on the side of the first light absorbing layer where the transparent undercoat layer is not disposed.

According to the light diffusion film of the above <5>, since the transparent adhesive layer is provided on the first light absorbing layer side, an adhesive surface to a liquid crystal panel or the like can be secured.

<6> The light diffusing film according to any one of <1> to <5>, wherein a transparent substrate is provided on a side of the second light absorbing layer on which the transparent undercoat layer is not disposed.

According to the light diffusing film of the above item <6>, the strength of the light diffusing film can be improved by having the transparent substrate on the second light absorbing layer side.

<7> a first light absorbing layer, a transparent undercoat layer disposed on one side of the first light absorbing layer, and a part partially exposed from the first light absorbing layer and another part A plurality of transparent beads embedded and fixed in the first light absorbing layer and the transparent undercoat layer, and the plurality of transparent beads on a side of the transparent undercoat layer where the first light absorbing layer is not arranged. A second light-absorbing layer having a non-light-absorbing region in the region corresponding to the beads, and a method for producing a light-diffusing film, comprising irradiating light from the first light-absorbing layer side, exposing and developing. A method for manufacturing a light diffusing film, comprising a light absorbing region forming step of forming a light absorbing region of the second light absorbing layer.

According to the method for producing a light diffusing film of the above <7>, light is irradiated from the first light absorbing layer side and exposed and developed, so that a non-light absorbing region is formed on the light path exiting from the transparent beads. Can be formed.

<8> A transparent undercoat layer forming step of forming the transparent undercoat layer on the surface of a transparent substrate, and embedding transparent beads in the transparent undercoat layer, and applying a first light absorbing layer coating solution. A light absorbing layer forming step, an adhesive layer forming step of forming a transparent adhesive layer on the surface of the first light absorbing layer, a peeling step of peeling the transparent base material from the undercoat layer surface, Second coating of the second light absorbing layer coating liquid
The light absorbing region forming step, after the second light absorbing layer applying step, irradiates light from the transparent adhesive layer side, and exposes and develops the second light absorbing layer. <7> The method for producing a light diffusion film according to <7>, wherein a light absorption region of the light absorption layer is formed.

According to the method for producing a light diffusion film of the above <8>, a high quality light diffusion film can be efficiently produced.

<9> The first light absorbing layer forming step comprises:
The method for producing a light diffusing film according to <7> or <8>, wherein a first light absorbing layer is formed by applying the first light absorbing layer coating liquid, and then exposing and curing to form a first light absorbing layer.

According to the method for producing a light diffusing film of <9>, the first light absorbing layer can be formed by exposing and curing.

<10> The first light absorbing layer forming step is characterized in that, after forming the first light absorbing layer, an excess portion of the first light absorbing layer is removed. <7> ~ <9
> A method for producing a light diffusion film.

According to the method for producing a light diffusing film of the above <10>, the transparent beads are applied when the first light absorbing layer coating liquid is applied in order to remove the surplus portion of the first light absorbing layer. There is no need to ensure exposure.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the light diffusion film of the present invention and a method for producing the same will be described in detail.

<< Light Diffusing Film >> The light diffusing film of the present invention comprises a first light absorbing layer, a transparent undercoat layer disposed on one side of the first light absorbing layer, and a first light absorbing layer. A plurality of transparent beads partially exposed and the other part embedded and fixed in the first light absorbing layer and the transparent undercoat layer,
Further, a second light absorbing layer having a non-light absorbing region in each region corresponding to the plurality of transparent beads is provided on a side of the transparent undercoat layer where the first light absorbing layer is not arranged. And The light diffusing film of the present invention has a first
By providing the second light absorbing layer in addition to the light absorbing layer, an image with high contrast can be obtained. Hereinafter, FIG.
The light diffusion film of the present invention will be described with reference to FIG.

FIG. 1 is a schematic sectional view showing the structure of the light diffusion film of the present invention. In FIG. 1, a light diffusion film 10 of the present invention comprises a first light absorbing layer 11, a transparent undercoat layer 12, a transparent bead 13, a second light absorbing layer 14,
Consists of A part of the transparent beads 13 penetrates the first light absorbing layer 11 and is embedded in the transparent undercoat layer 12, and a part of the transparent beads 13 is exposed from the first light absorbing layer 11. The first light absorbing layer 11 has a light absorbing property and improves the contrast of an obtained image. In addition, the transparent undercoat layer 12
In order to improve the transmission efficiency of the incident light, it is provided to secure an opening 13a of the transparent bead 13 indicated by a hatched portion in FIG.

The second light absorbing layer 14 has a non-light absorbing area 14 a in each area corresponding to the transparent beads 13,
The region other than the non-light absorbing region 14a is occupied by the light absorbing region 14b. In addition, `` each area corresponding to a plurality of transparent beads '' does not necessarily mean that all transparent beads need to have an area corresponding to this area, and an area corresponding to the transparent bead does not impair the effects of the present invention. What is necessary is just to be secured. The non-light absorbing region 14a is
In other words, the light diffusion film 10 of the present invention reduces the transmission efficiency of the incident light because it is formed in the region corresponding to The light absorbing property can be improved by the light absorbing region 14b without the need, and a high-contrast image can be obtained.

Hereinafter, each member usable in the present invention will be described.

(Transparent beads) The material of the above-mentioned transparent beads is not particularly limited, and various materials may be used as long as it is transparent. Specifically, materials such as glass and inorganic oxide-containing vinyl acetate resin , Ethylene-vinyl acetate copolymer,
Vinyl chloride resin, vinyl chloride-vinylidene chloride copolymer,
(Meth) acrylic ester resin, butyral resin, silicone resin, polyester, vinylidene fluoride resin, nitrocellulose resin, polystyrene, styrene-acryl copolymer, urethane resin, polyethylene, polypropylene, polyethylene chloride, rosin derivative, etc. Can be These resins and the like may be used alone,
More than one species may be used in combination. Particularly, from the viewpoint of good optical characteristics, a (meth) acrylic resin, glass, and a material containing an inorganic oxide are preferably exemplified.

The shape of the transparent beads is particularly preferably spherical. The transparent beads used in the present invention preferably have various particle sizes depending on the standard monitoring distance of the display device to be applied. The angular resolving power of the human eye is about 50 to 200 microradians due to its structure. Therefore, the size of the transparent beads is preferably smaller than the viewing angle in order not to make the image feel rough. For example, assume that the standard monitoring distance of a desktop display device (for example, a display device for a personal computer) is 30 cm, and the standard monitoring distance of a home television is 2 m. Viewing angle 50
Applying microradians to these standard monitoring distances and converting to particle size, 15 μm and 100 μm respectively
Becomes Actually, since the monitoring distance has a certain width, in consideration of this, when the transparent beads are used for a light diffusion film for a desktop display device, the volume average particle diameter of the transparent beads is 0.5 to 50 μm. And preferably 0.5
To 30 μm, more preferably 0.5 to 12 μm.
m is particularly preferred. It is preferable to use transparent beads having a volume average particle size of 0.5 to 50 μm as the transparent beads of the light diffusion film of the present invention, because the roughness of the image (granularity) can be suppressed in any application. .

It is preferable that the transparent beads are arranged more densely to form an array. It is preferable that the transparent beads are densely arranged because the displayed image becomes smoother. For example, by using two or more types of transparent beads having different sizes, the size thereof is adjusted so that small-sized particles are arranged in the gap between large-sized particles, and the transparent beads can be arranged more densely. .

The transparent beads are preferably subjected to a surface hydrophobic treatment. If the transparent beads have been subjected to a surface hydrophobization treatment, the affinity for the light absorbing layer coating solution is reduced, so that when removing the excess part of the light absorbing layer, the removal becomes easy, and the area of the light incident part is reduced. Can be easily increased. Examples of the method of the surface hydrophobizing treatment include a known surface hydrophobizing method, for example, a method of immersing the transparent beads in an F-based silane coupling solution for one hour.

(First Light Absorbing Layer) The first light absorbing layer contains a light absorbing material. As the light absorbing substance, a black colorant (other than carbon black, a conventionally known black dye)
And a resin dyed with a black colorant, a negative photosensitive coloring material, and the like. When the first light absorbing layer is formed of a resin containing a black colorant dispersed therein or a resin dyed with a black colorant, the first light absorbing layer is further cured by irradiation with light such as a polymerizable monomer or a polymerization initiator. Contains substances that produce substances. Examples of the negative-type photosensitive color-forming material include ordinary negative-type black-and-white silver halide light-sensitive materials. The negative-type black-and-white silver halide light-sensitive material is described in Maruzen Bookstore "Science Photograph Handbook". . Examples of the negative photosensitive coloring material include those containing a triphenylmethane-based leuco dye precursor, a photoacid generator, a photoradical generator, and a radical quencher. As the negative photosensitive coloring material, a microcapsule includes a leuco dye precursor such as leuco crystal violet, a photoacid generator such as bromomethylphenylsulfone, and a photoradical generator such as roffin dimer. A capsule in which a radical quencher such as phenidone is arranged outside the capsule can be used. In the negative-type photosensitive coloring material, exposed portions generate radicals and oxidize the leuco dye precursor to form a color, whereas unexposed portions cause radical quencher to enter the capsule by a subsequent heat treatment. Thus, a stable negative-type photosensitive color-forming material is obtained by a mechanism for preventing color formation. These are described in JP-A-5-61190 and JP-A-9-218482.

The resin constituting the first light absorbing layer includes vinyl acetate resin, ethylene-vinyl acetate copolymer, vinyl chloride resin, vinyl chloride-vinylidene chloride copolymer, and (meth) acrylate resin. , Butyral resin, silicone resin, polyester, vinylidene fluoride resin, nitrocellulose resin, polystyrene, styrene
Examples include acrylic copolymers, urethane resins, polyethylene, polypropylene, polyethylene chloride, rosin derivatives, and mixtures thereof.

Examples of the polymerizable monomer include compounds capable of addition polymerization having at least two ethylenically unsaturated bonds, and are appropriately selected from compounds having two or more terminal ethylenically unsaturated bonds in one molecule. it can. For example, monomers, prepolymers, that is, dimers, trimers and oligomers, or mixtures thereof, and those having a chemical structure such as a copolymer thereof may be used.

Specifically, unsaturated carboxylic acids (for example,
Acrylic acid, methacrylic acid, itaconic acid, crotonic acid,
Esters of isocrotonic acid, maleic acid, etc.) with aliphatic polyhydric alcohol compounds, and amides of unsaturated carboxylic acids with aliphatic polyamine compounds.

Examples of the ester (monomer) of the unsaturated carboxylic acid and the aliphatic polyhydric alcohol compound include acrylic acid esters such as ethylene glycol diacrylate and triethylene glycol diacrylate.
1,3-butanediol diacrylate, tetramethylene glycol diacrylate, propylene glycol diacrylate, neopentel glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane tri (acryloyloxypropyl)
Ether, trimethylolethane triacrylate, hexanediol diacrylate, 1,4-cyclohexanediol diacrylate,

Tetraethylene glycol diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexa Acrylate, tri (acryloyloxyethyl) isocyanurate, polyester acrylate oligomer and the like,

Examples of the methacrylate include tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, ethylene glycol dimethacrylate, and 1,3-butane. Diol dimethacrylate, hexanediol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol dimethacrylate, dipentaerythritol hexamethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate, bis [p-
(3-methacryloxy-2-hydroxypropoxy)
Phenyl] dimethylmethane, bis [p- (methacryloxyethoxy) phenyl] dimethylmethane and the like,

Examples of itaconic esters include ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate and pentane. Erythritol diitaconate, sorbitol tetritaconate and the like,

Examples of the crotonic acid ester include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, and sorbitol tetradicrotonate. Examples of the isocrotonic acid ester include ethylene glycol diisocrotonate. Crotonate, pentaerythritol diisocrotonate, sorbitol tetraisocrotonate and the like,

Examples of the maleic acid ester include ethylene glycol dimaleate, triethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate. Furthermore, a mixture of the above-mentioned various esters can also be mentioned.

Examples of the amide (monomer) of the unsaturated carboxylic acid and the aliphatic polyamine compound include, for example, methylenebis-acrylamide, methylesbis-methacrylamide, 1,6-hexamethylenebis-acrylamide, 1,6-hexaamide Methylenebis-methacrylamide,
Examples include diethylenetriaminetrisacrylamide, xylylenebisacrylamide, xylylenebismethacrylamide, and the like.

As another example, see JP-B-48-417.
No. 08-208, in which a hydroxyl group-containing vinyl monomer represented by the following general formula (A) is added to a polyisocyanate compound having two or more isocyanate groups in one molecule. A vinyl urethane compound containing a polymerizable vinyl group is exemplified. CH ₂ ＣC (R) C
OOCH ₂ CH (R ′) OH General formula (A) wherein R and R ′ represent H or CH ₃ . ]

Also, urethane acrylates described in JP-A-51-37193, JP-A-48-64183.
No., JP-B-49-43191, JP-B-52-3049
Polyfunctional acrylates and methacrylates, such as polyester acrylates and epoxy acrylates obtained by reacting an epoxy resin with (meth) acrylic acid, described in JP-A No. 0 and the like can be mentioned. Furthermore, Journal of the Adhesion Society of Japan (vo 1.20, No. 7, pp. 300-308 (19)
1984)) as photocurable monomers and oligomers.

The polymerizable monomers may be used alone or in combination of two or more. As the content of the polymerizable monomer in the coating solution for the light absorbing layer,
5-30 mass% is preferable, and 10-20 mass% is more preferable.

The polymerization initiator is capable of substantially initiating photopolymerization of the polymerizable monomer,
Any compound capable of initiating the polymerization reaction of the polymerizable monomer can be used. Above all, about 300-
It preferably contains at least one component having a molecular extinction coefficient of at least about 50 in a wavelength region of 500 nm, and is sensitive to light in the ultraviolet region. Further, a photo-excited sensitizer, for example, an activator that generates an active radical with some interaction with a decolorizable dye described below may be used.

Examples of the polymerization initiator include halogenated hydrocarbon derivatives, ketone compounds, ketoxime compounds, organic peroxides, thio compounds, hexaarylbiimidazole, aromatic onium salts, ketoxime ethers,
JP-A-2-48664, JP-A-1-152449
Aromatic ketones, lophine dimers, benzoin, benzoin ethers, polyhalogens, and combinations of two or more of these compounds described in JP-A No. 2-153353.

Among them, halogenated hydrocarbon compounds having a triazine skeleton, ketoxime compounds, hexaarylbiimidazole, 4,4'-bis (diethylamino) benzophenone, because of their excellent photosensitivity, storage stability, adhesion to substrates, and the like. And 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2,4-bis (trichloromethyl) -6- [4- (N, N-diethoxycarbonylmethylamino) -3 -Bromophenyl] -s-
A system using triazine and 4- [p-N, N-di (ethoxycarbonylmethyl) -2,6-di (trichloromethyl) -s-triazine] is preferable.

Examples of the halogenated hydrocarbon compound having a triazine skeleton include those described in Bull. Chem.
Soc. Japan, 42, 2924 (Wakabayashi et al., 19
69) [for example, 2-phenyl-4,6
-Bis (trichloromethyl) -s-triazine, 2-
(P-chlorophenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-tolyl) -4,6
-Bis (trichloromethyl) -s-triazine, 2-
(P-methoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (2 ′, 4′-dichlorophenyl) -4,6-bis (trichloromethyl) -s
-Triazine, 2,4,6-tris (trichloromethyl) -s-triazine, 2-methyl-4,6-bis (trichloromethyl) -s-triazine, 2-n-nonyl-
4,6-bis (trichloromethyl) -s-triazine,
2- (α, α, β-trichloroethyl) -4,6-bis (trichloromethyl) -s-triazine and the like],

Compounds described in British Patent No. 1388492 [for example, 2-styryl-4,6-bis (trichloromethyl) -s-triazine, 2- (p-methylstyryl) -4,6-bis (trichlor Methyl) -s-triazine, 2- (p-methoxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-methoxystyryl) -4-amino-6-trichloromethyl-s- Triazine, etc.] and the compounds described in JP-A-53-133428 [eg, 2- (4-methoxy-naphth-1-yl) -4,6-bis-trichloromethyl-s
-Triazine, 2- (4-ethoxy-naphth-1-yl) -4,6-bis (trichloromethyl) -s-triazine, 2- [4- (2-ethoxyethyl) -naphth-1
-Yl] -4,6-bis (trichloromethyl) -s-triazine, 2- (4,7-dimethoxy-naphth-1-yl) -4,6-bis (trichloromethyl) -s-triazine, 2- (Acenaphth-5-yl) -4,6-bis (trichloromethyl) -s-triazine and the like],

Compounds described in DE 33 33 024 [for example, 2- (4-styrylphenyl) -4,
6-bis (trichloromethyl) -s-triazine, 2-
(4-p-methoxystyrylphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (1-naphthylvinylenephenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- Chlorostyrylphenyl-4,6-bis (trichloromethyl) -s-triazine, 2- (4-thiophen-2-vinylenephenyl)-
4,6-bis (trichloromethyl) -s-triazine,
2- (4-thiophen-3-vinylenephenyl) -4,
6-bis (trichloromethyl) -s-triazine, 2-
(4-furan-2-vinylenephenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (4-benzofuran-2-vinylenephenyl) -4,6-bis (trichloromethyl) -s- Triazine, etc.),

J. Org. Chem. (FC Sch
aefer et al., 29, 1527 (1964)] [eg, 2-methyl-4,6-bis (tribromomethyl) -s-triazine, 2,4,6-tris (tribromomethyl) -s -Triazine, 2,4,6-tris (dibromomethyl) -s-triazine, 2-amino-
4-methyl-6-tribromomethyl-s-triazine,
2-methoxy-4-methyl-6-trichloromethyl-s
-Triazine, etc.),

Compounds described in JP-A-62-58241 [eg, 2- (4-phenylacetylenephenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (4-naphthyl-1) -Acetylenephenyl)
-4,6-bis (trichloromethyl) -s-triazine, 2- (4-p-tolylacetylenephenyl) -4,
6-bis (trichloromethyl) -s-triazine, 2-
(4-p-methoxyphenylacetylenephenyl)-
4,6-bis (trichloromethyl) -s-triazine,
2- (4-p-isopropylphenylacetylenephenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (4-p-ethylphenylacetylenephenyl) -4,6-bis (trichloromethyl)- s-triazine, etc.),

Compounds described in JP-A-5-281728 [eg, 2- (4-trifluoromethylphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (2,6-difluoro Phenyl) -4,6-
Bis (trichloromethyl) -s-triazine, 2-
(2,6-dichlorophenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (2,6-dibromophenyl) -4,6-bis (trichloromethyl) -s
-Triazine and the like].

The ketoxime compound includes, for example, a compound represented by the following general formula (B).

[0063]

Embedded image

In the above formula (B), R ² and R ³ each independently represent a hydrocarbon group or a heterocyclic group which may have a substituent and may have an unsaturated bond. And may be the same or different. R ⁴ and R ⁵ each independently represent a hydrogen atom, a hydrocarbon group which may have a substituent, may have an unsaturated bond, a heterocyclic group,
It represents a hydroxyl group, a substituted oxy group, a mercapto group, or a substituted thio group, which may be the same or different. Further, R ⁴ and R ⁵ may be bonded to each other to form a ring, in which case the ring is represented by —O—, —NR ⁶ —, —O—C
O -, - NH-CO - , - S- and -SO ₂ - at least one divalent group connecting backbone as which may contain an alkylene group having a carbon number of 2-8 ring selected from Represent. R ⁶ and R ⁷ each independently represent a hydrogen atom, a hydrocarbon group which may have a substituent and may contain an unsaturated bond, or a substituted carbonyl group.

Specific examples of the compound represented by formula (B) are shown below, but it should not be construed that the invention is limited thereto.
For example, p-methoxyphenyl-2-N, N-dimethylaminopropylketone oxime-O-allyl ether,
p-methylthiophenyl-2-morpholinopropyl ketone oxime-O-allyl ether, p-methylthiophenyl-2-morpholinopropyl ketone oxime-O
-Benzyl ether, p-methylthiophenyl-2-morpholinopropyl ketone oxime-On-butyl ether, p-morpholinophenyl-2-morpholinopropyl ketone oxime-O-allyl ether, p-methoxyphenyl-2-morpho Linopropyl ketone oxime-On-dodecyl ether, p-methylthiophenyl-2-morpholinopropyl ketone oxime-O-
Methoxyethoxyethyl ether,

P-Methylthiophenyl-2-morpholinopropyl ketone oxime-Op-methoxycarbonylbenzyl ether, p-methylthiophenyl-2-morpholinopropyl ketone oxime-O-methoxycarbonyl methyl ether, p-methylthiophenyl- 2-
Morpholinopropyl ketone oxime-O-ethoxycarbonyl methyl ether, p-methylthiophenyl-2
-Morpholinopropyl ketone oxime-O-4-butoxycarbonylbutyl ether, p-methylthiophenyl-2-morpholinopropyl ketone oxime-O-2
-Ethoxycarbonylethyl ether, p-methylthiophenyl-2-morpholinopropyl ketone oxime-
O-Methoxycarber-3-propenyl ether, p
-Methylthiophenyl-2-morpholinopropyl ketone oxime-O-benzyloxycarbonyl methyl ether;

The above hexaarylbiimidazole includes, for example, 2,2′-bis (o-chlorophenyl)-
4,4 ′, 5,5′-tetraphenylbiimidazole,
2,2′-bis (o-bromophenyl) -4,4 ′,
5,5′-tetraphenylbiimidazole, 2,2′-
Bis (o, p-dichlorophenyl) -4,4 ', 5
5′-tetraphenylbiimidazole, 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetra (m-methoxyphenyl) biimidazole, 2,2′-
Bis (o, o'dichlorophenyl) -4,4 ', 5
5'-tetraphenylbiimidazole, 2,2'-bis (o-nitrophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o-methylphenyl) -4 , 4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o-trifluoromethylphenyl) -4,4', 5,5'-tetraphenylbiimidazole and the like. These biimidazoles are described, for example, in Bull. Chem. Soc. Japan
n, 33, 565 (1960) and J.A. Org. Ch
em, 36 (16) 2262 (1971).

The ketoxime ethers include, for example, 3-benzoyloximinobtan-2-one,
Acetoxyiminobutan-2-one, 3-propionyloxyiminobutan-2-one, 2-acetoxyiminopentan-3-one, 2-acetoxyimino-1-phenylpropan-1-one, 2-benzoyloxyimino-
1-phenylpropan-1-one, 3-p-toluenesulfonyloxyimiminobtan-2-one, 2-ethoxycarbonyloxyimino-1-phenylpropan-1-
ON and the like.

The above polymerization initiators may be used alone or in combination of two or more. It is also possible to use several compounds in combination of different types. The content of the polymerization initiator in the light absorbing layer coating solution,
0.1-5.0 mass% is preferable, and 0.2-1.0 mass% is more preferable.

(Transparent Undercoat Layer) In the present invention, the transparent undercoat layer is preferably formed of a resin having a light transmitting property and capable of fixing transparent beads. Further, it is preferable that the transparent bead is made of a thermoplastic resin which is softened by the application of heat so that a part of the transparent beads disposed on the transparent undercoat layer can be embedded. Specifically, vinyl acetate resin, ethylene-vinyl acetate copolymer, vinyl chloride resin, vinyl chloride-vinylidene chloride copolymer, (meth) acrylate resin, butyral resin, silicone resin, polyester, vinylidene fluoride resin It is preferable to use nitrocellulose resin, polystyrene, styrene-acryl copolymer, urethane resin, polyethylene, polypropylene, chlorinated polyethylene, rosin derivative, water-soluble nylon, and a mixture thereof.

The thickness of the transparent undercoat layer is not particularly limited, but it is preferable that the thickness is such that the transparent beads can be fixed uniformly and the beads are not lost, and it depends on the particle size of the transparent beads used. Therefore, although it cannot be said unconditionally, the thickness is preferably such that at least half of the volume of the transparent beads is exposed from the transparent undercoat layer. However, if the thickness of the transparent undercoat layer is too large, the contrast is reduced. When the volume average particle diameter of the transparent beads is about 0.5 to 50 μm, the thickness of the transparent undercoat layer is preferably 0.1 to 15 μm, and 0.1 to 15 μm.
1-12 μm is more preferable, and 0.1-9 μm is particularly preferable.

(Second Light Absorbing Layer) The second light absorbing layer has a structure in which a light absorbing region has a light absorbing property and a non-light absorbing region has a high light transmitting property. As such a configuration, for example, only the light-absorbing region is colored and the non-light-absorbing region is transparent, or the light-absorbing region is made of a light-absorbing material, and the non-light-absorbing region is a light-transmitting material. A configuration consisting of The second light-absorbing layer according to the present invention includes a configuration in which only the light-absorbing region is formed by a convex portion made of a light-absorbing substance, and the concave portion serves as a non-light-absorbing region corresponding to the transparent beads. It is. In addition, from the viewpoint of utilizing a manufacturing method of the present invention described below (hereinafter, sometimes referred to as “self-alignment”), only the light absorbing region of the second light absorbing layer is colored, A configuration in which the region is transparent is preferable.

The member usable for the second light absorbing layer is not particularly limited as long as it can form the above-mentioned structure. For example, the light absorbing material may be the same as that of the first light absorbing layer. Can be used. From the viewpoint of utilizing self-alignment described later, it is preferable to use a positive photosensitive coloring material from the viewpoint of quality and manufacturing efficiency. Further, as a resin constituting the second light absorption layer, a vinyl acetate resin, an ethylene-vinyl acetate copolymer,
Vinyl chloride resin, vinyl chloride-vinylidene chloride copolymer,
(Meth) acrylate resin, butyral resin, silicone resin, polyester, vinylidene fluoride resin, nitrocellulose resin, polystyrene, styrene-acryl copolymer, urethane resin, polyethylene, polypropylene, polyethylene chloride, rosin derivative, and these Mixtures and the like can be used.

Examples of the positive photosensitive coloring material include a thermoresponsive microcapsule containing an electron-donating colorless dye and a compound having an electron acceptor and a polymerizable vinyl monomer in the same molecule. , A photopolymerization initiator,
And the like. In the positive photosensitive coloring material, these compounds and the photopolymerization initiator exist outside the thermoresponsive microcapsules. In the positive photosensitive coloring agent material, in the exposed area, the composition (hereinafter referred to as a curable composition) outside the thermo-responsive microcapsules is cured (polymerized) and fixed, so that it is heated by subsequent heating. Also, the compound does not move, while the unexposed portion is not fixed by heating, so that a compound having a mobile electron accepting portion and a polymerizable Bier monomer portion or an electron accepting compound passes through the coloring material. It is a recording material that moves to develop a colorless electron-donating dye in the microcapsules to form a positive image. The positive type photosensitive coloring material is described in detail in JP-A-10-226174.

In addition, other than this, as long as it is a positive type photosensitive coloring material, JP-A-3-87827 and JP-A-4-27827 can be used.
The coloring material (photosensitive heat-developable recording material) disclosed in Japanese Patent No. 11252 can also be suitably used. Further, a preferable example of a positive photosensitive color-forming material is a positive-type diazo photosensitive heat-sensitive material (photosensitive material) that contains at least a diazonium salt, a coupler, and a base so that an exposed portion becomes non-colored and heated to form a color in an unexposed portion. Heat developing material). As a preferable form of the photosensitive color-forming material, an oil-soluble diazonium salt is contained in a microcapsule,
The coupler and the base are arranged outside the capsule in a form emulsified and dispersed together with other sensitizers and the like. In the exposed part, the diazonium salt loses the coupling function and does not develop color, whereas in the unexposed part, the coupler, base and sensitizer melted by heating enter the capsule and couple with the diazonium salt. A color develops upon reaction. This positive-type diazo photosensitive heat-sensitive material is described in detail in JP-A-4-261893.

Another preferable example of the positive type photosensitive coloring material includes a positive type silver halide photosensitive emulsion, the exposed portion becomes non-colored, and the unexposed portion is formed by photographic development, fixing and washing. Positive photosensitive color-forming materials for color-developing portions. Preferred examples of the positive silver halide light-sensitive emulsion include a direct reversal emulsion for micro-dupe film and a direct reversal emulsion for radiographic duplication. Normally, in a negative-working silver halide emulsion, a photosensitive nucleus is generated in an exposed portion, and this is reduced to metallic silver by development to form a black image.However, in a positive-working silver halide emulsion, If silver halide is previously covered and a desensitizing dye is added thereto, the exposed portions are not reduced, and the unexposed portions are reduced to form colored silver.
The positive type direct reversal emulsion is described in, for example, "Scientific Photograph Handbook" published by Maruzen Shoten. For developing, fixing and washing with a positive-working silver halide emulsion, a usual processing solution for a black-and-white emulsion is suitably used.

The thickness of the second light-absorbing layer is not particularly limited as long as the contrast can be sufficiently prevented from lowering. For example, when transparent beads having a volume average particle size of about 0.5 to 50 μm are used. The thickness of the second light absorbing layer is preferably 0.3 to 30 μm.

(Transparent Adhesive Layer) The light diffusion film of the present invention may have a structure in which the first light absorbing layer has a transparent adhesive layer on the side where the transparent undercoat layer is not disposed (on the exposed transparent beads). FIG. 2 is a schematic sectional view showing the configuration of the light diffusion film of the present invention having a transparent adhesive layer. In addition,
The same members as those in FIG. 1 are denoted by the same reference numerals, and detailed description is omitted. The transparent adhesive layer 15 is a layer that has high light transmittance and adheres to other members (adhesion by supplying heat as desired) when incorporated in a liquid crystal display device or the like. In the self-alignment described below, the transparent substrate needs to be peeled off in order to apply the second light-absorbing layer coating solution. Therefore, the transparent adhesive layer is coated with the second light-absorbing layer coating solution. In some cases, it plays a role in maintaining the strength of the light diffusion film.

As a material constituting the transparent adhesive layer, for example, an adhesive of a solution type, an emulsion type, a hot melt type, a pressure sensitive type, or the like can be used. Specific examples include an acrylic resin, a carbonate resin, a vinyl chloride resin, a polyolefin resin, a polyester resin, and a polystyrene resin. The transparent adhesive layer formed from these materials takes into account the refractive index of the transparent beads,
It can be used in combination with the transparent beads. The thickness of the transparent adhesive layer is not particularly limited, but is preferably high in surface smoothness in terms of improving the adhesiveness. Therefore, it is preferable that at least the irregularities on the surface derived from the plurality of transparent beads (transparent bead array) are eliminated by forming the transparent adhesive layer.

(Transparent substrate) The light diffusion film of the present invention
The second light absorbing layer may have a transparent substrate on the side where the transparent undercoat layer is not disposed. FIG.
It is a schematic sectional view showing composition of a light diffusion film of the present invention which has a transparent substrate. The same members as those in FIG. 1 are denoted by the same reference numerals, and detailed description will be omitted. The transparent substrate 16 has sufficient mechanical strength according to the application. The transparent base material 16 may be adhered to the second light absorbing layer after forming the second light absorbing layer, or the second light absorbing layer may be formed on the transparent base material 16 in the manufacturing process of the light diffusion film. A layer, a transparent undercoat layer, and the like may be formed.

As the transparent substrate, it is preferable to use a material having sufficient light transmittance and having sufficient mechanical strength according to the use. Specifically, various glass plates, polyester, polyolefin, polyamide, polyether, polyethylene terephthalate (PE
T), films made of various resin materials such as polyethylene naphthalate (PEN), polystyrene, polyester amide, polycarbonate, polyphenylene sulfide, polyetherester, polyvinyl chloride, and polymethacrylate.

The light-diffusing film of the present invention is a light-transmitting screen of a rear-transmission display device, a light-diffusing film for enlarging a viewing angle of a liquid crystal display device, a plasma display device, an electroluminescence display device, or the like, or a backing for a liquid crystal display device. The present invention can be used for a light diffusion film that diffuses light such as a light and various illumination light sources. In particular, it is preferably used for a light diffusion film for widening the viewing angle of the above various display devices.

<< Method for Producing Light Diffusion Film >> The method for producing the light diffusion film of the present invention described above is not particularly limited as long as the light diffusion film of the present invention can be produced. From the viewpoint, it is preferable to use the manufacturing method (self-alignment) of the present invention described below. Hereinafter, the production method of the present invention will be described in detail.

The manufacturing method of the present invention includes a light absorbing region forming step of irradiating light from the first light absorbing layer side, exposing and developing to form a light absorbing region of the second light absorbing layer. It is characterized by. According to the manufacturing method of the present invention, a positive photosensitive coloring material is used for the second light absorption layer, and the second light absorption is performed by light that is incident from the first light absorption layer side and emitted to the observer side through the transparent beads. The light path in the layer is exposed and developed to form a light absorbing region in the unexposed area. Since the production method of the present invention includes the light absorbing region forming step, it is possible to form the non-absorbing region in the region corresponding to the transparent beads without performing alignment or the like, so that the production efficiency is excellent, and A high quality light diffusion film can be manufactured. Further, since the light path emitted from the transparent beads is a non-light absorbing region, the transmission efficiency of incident light is not reduced.

<Light Absorbing Region Forming Step> The light absorbing region forming step will be described with reference to FIG. FIG. 4 is a conceptual diagram for explaining the light absorbing region forming step in the present invention. Note that the same members as those in FIGS. 1 to 3 are denoted by the same reference numerals, and detailed description thereof is omitted. First,
Transparent adhesive layer 15, first light absorbing layer 11, transparent beads 1
3. A second light absorbing layer coating solution is applied to the surface of the transparent undercoat layer 12 of the light diffusion film intermediate product 40 (see FIG. 4A) composed of the transparent undercoat layer 12 to form a light absorbing region. A second light absorbing layer 14c not formed is formed (FIG. 4).
(B)). The second light absorbing layer 14c is formed of the above-described positive type photosensitive coloring material. Next, when light is irradiated from the direction of the arrow in FIG. 4C, the light incident on the transparent beads is emitted while diffusing to the second light absorbing layer 14c side. At this time, the output light path of the incident light (FIG. 4)
(A region in a V-shape indicated by a chain line in (c)) is exposed. Since the second light-absorbing layer 14c is formed of a positive-type photosensitive coloring material, when the second light-absorbing layer 14c is developed, only the unexposed portions are colored, and the unexposed portions have the light absorbing regions 14b. Is formed, and the second light absorbing layer 14 having the light absorbing region 14b and the non-light absorbing region 14a is formed (see FIG. 4D). In FIG. 4, the light diffusion film intermediate product 40 has a configuration including the transparent adhesive layer 15. However, even if the configuration does not include the transparent adhesive layer 15, the second light absorbing layer is formed in the same manner. A light absorbing region can be formed on the substrate.

(Exposure) Exposure is performed by inputting substantially parallel light from the transparent adhesive layer 15 side. Then, the light that has entered the beads 13 is refracted, enters the second light absorption layer 14, and the region is exposed. That is, only the region of the second light absorbing layer 14 through which light passes is exposed, and becomes a light passing region that does not develop color even when developed. As the light source, for example, a Xe (xenon) lamp can be used. The illumination time can be set freely according to the thickness of the second light absorbing layer.

(Development) In the step of forming the light absorbing region, the developing method is not limited, but it is preferable to perform development by heat from the viewpoint of working efficiency. The heating time and the heating temperature can be freely set according to the thickness of the second light absorbing layer.

<Other Steps> In the manufacturing method of the present invention, steps other than the light absorbing region forming step are not particularly limited, but before the light absorbing region forming step, a transparent undercoat layer forming step described below is performed. A method including a first light-absorbing layer forming step, an adhesive layer forming step, a peeling step, and a second light-absorbing layer applying step is preferable for more efficiently performing the self-alignment. Hereinafter, an example of the manufacturing method of the present invention will be described with reference to FIG. In FIG. 5, the same members as those in FIGS. 1 to 4 are denoted by the same reference numerals, and detailed description is omitted.

FIG. 5 is a conceptual diagram showing an example of the manufacturing method of the present invention. (Transparent undercoat layer forming step) First, in the transparent undercoat layer forming step, a transparent base material 16 is prepared (see FIG. 5A), and a coating solution containing a thermoplastic resin is applied to the surface of the transparent base material 16. And drying to form a transparent undercoat layer 12 (FIG. 5).
(B)).

(First Light Absorbing Layer Forming Step) In the first light absorbing layer forming step, a plurality of transparent beads 13 are densely dispersed and arranged on the transparent undercoat layer 12 (see FIG. 5C). Then, it is embedded in the transparent undercoat layer 12 (see FIG. 5D).
According to the manufacturing method of the present invention, by embedding the transparent beads 13 before forming the first light absorbing layer, even if the embedding of the transparent beads is somewhat uneven, a depth sufficient for light emission can be easily obtained. The transparent beads are embedded in the light diffusion film, and a light diffusion film having high transmission efficiency and high viewing angle characteristics can be obtained.

In the above-mentioned embedding, it is preferable that the transparent beads 13 are evenly embedded in the transparent undercoat layer 12. By burying the transparent beads 13 uniformly, high uniformity of the light emitting portion can be maintained, and a light diffusion film having high transmission efficiency can be obtained. Further, it is preferable that the transparent beads 13 are buried in the transparent undercoat layer 12 so as to be arranged as closely as possible. By embedding the transparent beads 13 densely, an image having a rough image quality can be obtained, and a light diffusion film having high transmission efficiency can be obtained.

In order to embed the transparent beads 13 densely in the transparent undercoat layer 12, for example, a method of arranging and burying the transparent beads 13 having different particle diameters may be mentioned. And transparent beads 13 having different particle sizes.
Are preferably arranged closely. Further, it is preferable that the transparent beads 13 are embedded such that at least half of the volume thereof is exposed from the transparent undercoat layer 12. By embedding in this way, a light diffusion film having high transmission efficiency can be obtained.

When the transparent beads 13 are embedded, heating may be performed as appropriate.
Any temperature may be used as long as it is a temperature at which the transparent beads 13 soften and the transparent beads 13 sink.
By embedding the transparent beads 13 while heating, the transparent beads 13 can be easily and sufficiently placed on the softened transparent undercoat layer 12.
Can be buried. Furthermore, it is preferable to place a heat conductive plate-like elastic body on the transparent beads 13 and pressurize the same during the heating, because the transparent beads 13 can be embedded more uniformly. The heat conductive plate-like elastic body is not particularly limited, but is preferably silicone rubber or the like. The pressure at the time of pressurization is not particularly limited as long as the transparent beads 13 are not damaged.

After embedding the transparent beads 13 in the transparent undercoat layer 12, a first light absorbing layer coating solution is applied to form the first light absorbing layer 11 (see FIG. 5E). The first light absorbing layer coating liquid contains a light absorbing substance and, if necessary, a surfactant and a solvent. Examples of the solvent include methyl ethyl ketone and propylene glycol monomethyl ether acetate. These may be used alone or in combination of two or more. As the surfactant, a known surfactant can be appropriately selected and used. The content of the surfactant in the first light absorbing layer coating liquid is preferably 0.1% by mass or less. If the content of the surfactant is 0.1% by mass or less,
The affinity between the coating solution for the light absorbing layer and the transparent beads 13 is low (the wettability is low), and the light passing loss due to the surplus portion is small. In addition, when the surplus portion of the first light absorbing layer is removed as described later, the removal becomes easy, and the area of the light incident portion can be easily increased. In addition, transparent beads 13
This effect is further enhanced if is subjected to a surface hydrophobic treatment.

In the first light absorbing layer forming step,
When the surplus portion of the first light absorbing layer 11 is removed, the first light absorbing layer 11 may be formed by using the above-mentioned negative type photosensitive coloring material, and then exposing and curing. . In this case, after the application of the first light-absorbing layer coating liquid, the portion of the first light-absorbing layer 11 excluding the transparent beads 13 is exposed and cured for the purpose of securing the area of the light incident portion. Light absorbing layer 1
Form one.

The method of the above-mentioned exposure is not particularly limited, and all the methods can be suitably applied as long as a method of exposing only a portion except on the transparent beads and not exposing the transparent beads as described above is possible. However, a method of irradiating ultraviolet rays from the transparent substrate side is preferable. In this method, the coating solution for the light absorbing layer contains a substance capable of forming a cured composition upon irradiation with ultraviolet light, and the transparent beads contain, for example, an ultraviolet absorbent (or vacuum deposition, coating, or the like). A thin film of an ultraviolet absorber is formed on the surface of the transparent beads, so that the coating solution for the light absorbing layer applied on the transparent beads is not exposed, and the light absorbing agent applied on portions other than on the transparent beads is not exposed. Only the layer coating solution can be exposed.

The transparent beads 13 contain an ultraviolet absorber, and the first light absorbing layer coating solution contains a substance which forms a cured composition by irradiation with ultraviolet rays, and is irradiated with ultraviolet rays from the transparent substrate side. When exposed to light, the ultraviolet absorber contained in the transparent beads absorbs the ultraviolet light, so that the ultraviolet light does not pass through the transparent beads. As a result, the coating solution for the light absorbing layer applied on or around the transparent beads does not cure,
It can be easily removed by a solvent or the like. Accordingly, a light diffusion film having a large light incident area, high transmission efficiency, excellent viewing angle characteristics, and low density unevenness can be easily obtained.

The content of the ultraviolet absorber in the transparent beads 13 is preferably 15 to 95% by mass. When the content is within the range of 15 to 95% by mass, the resin has a sufficient ultraviolet light absorbing effect, and the first coating material applied on transparent beads or the like.
Of the light absorbing layer coating liquid can be prevented. In addition, the transparent beads 1 are formed by vacuum deposition or coating.
3 is also suitable in which a thin film of an ultraviolet absorbent is formed on the surface. Examples of the ultraviolet absorber include, for example, titanium oxide, zinc oxide, phthalocyanine-based pigments, benzotriazole-based UV absorbers, and the like.
Titanium oxide is particularly preferred in that it has excellent light diffusion properties.

Further, if the surface of the transparent beads 13 is subjected to a hydrophobic treatment, the affinity between the transparent beads 13 and the first light absorbing layer coating solution is lowered, so that the removal of the surplus portion becomes easy. Further, when the surface of the transparent beads 13 is subjected to a hydrophobic treatment, the coating liquid for the first light absorbing layer is less likely to flow into the contact portion between the transparent beads 13 and the transparent undercoat layer 12 as described above. Is reduced, and a light diffusion film having high transmission efficiency can be easily manufactured.
As the method of the above-mentioned hydrophobizing treatment, a known hydrophobizing treatment method can be used, and for example, a method of immersing the transparent beads 13 in an F-based silane coupling liquid for one hour or the like can be mentioned.

The thickness of the cured region can be controlled by appropriately changing the exposure conditions.
When a method of irradiating ultraviolet rays from the transparent substrate 16 side is used as the exposure method, the transparent substrate 16 needs to be transparent to both visible light and ultraviolet rays.

—Removal of Excess Portion— In the first light absorption layer forming step, it is preferable to remove the excess portion of the first light absorption layer after forming the first light absorption layer. Here, the “surplus part of the first light absorption layer”
In the first light absorbing layer, it refers to a portion that blocks incident light to the transparent beads 13 more than the setting. The removal of the surplus portion is performed by appropriately changing the setting conditions (temperature, pressure, time, etc.) of the removal to control the removal region in the thickness direction.

The above-mentioned removing method is not particularly limited as long as the surplus portion of the first light absorbing layer can be removed uniformly. However, it is possible to remove fine portions precisely and to reduce the contamination. Known dry etching such as reactive ion etching is preferable, and low temperature plasma etching is particularly preferable. As the low-temperature plasma etching,
Oxygen plasma etching using oxygen as a reaction gas is most preferred. The plasma etching is performed, for example, by the following method.

After the formation of the first light absorbing layer, a light diffusion film is placed in a quartz cylindrical chamber, and a reaction gas is flowed under reduced pressure in the quartz chamber. A high-frequency electric field is applied to an electrode outside the quartz chamber to generate plasma and generate highly activated reactive species (radicals). Oxygen plasma etching is a method in which oxygen is used as a reaction gas, oxygen radicals are generated, and the first light absorption layer is favorably etched.

By the above removal, the surplus portion of the first light absorbing layer is uniformly removed, so that the area of the light incident portion is large, and the transmission efficiency and the viewing angle characteristics are excellent. Also, the occurrence of density unevenness due to the thickness variation of the first light absorbing layer is small.

It is also preferable to use a negative photosensitive coloring material for the first light absorbing layer, expose and cure the first light absorbing layer, and remove the unexposed portions. In this case, the first
Since the unexposed portion of the light absorbing layer is uniformly removed, the resulting light diffusion film has a large light incident area, and is excellent in transmission efficiency and viewing angle characteristics. Also, the occurrence of density unevenness due to the thickness variation of the first light absorbing layer is small. It is preferable to remove the unexposed portions by using a solvent or an alkaline developer. As the solvent, it is particularly preferable to use the same type of solvent as used in the first light absorbing layer coating solution.

(Adhesive Layer Forming Step) In the adhesive layer forming step, a coating solution containing an acrylic resin or the like is applied to the first light absorbing layer 11.
Then, the transparent adhesive layer 15 is formed by coating the transparent beads 13 exposed from the first light absorbing layer.
(F)). A known method can be used as appropriate for the method of application.

(Peeling Step) In the peeling step, the transparent undercoat layer 1
In order to apply the second light absorbing layer coating solution to the surface of the second substrate 2, the transparent substrate 16 is peeled off from the transparent undercoat layer 12 (FIG. 5).
(G)). In this method, the strength of the light diffusion film intermediate product is reduced because the transparent substrate 16 is peeled off. However, since the transparent adhesive layer 15 is formed in the adhesive layer forming step, the second light absorption The required mechanical strength can be maintained in the layer coating process.

(Second Light Absorbing Layer Coating Step) In the second light absorbing layer coating step, the above-mentioned second light absorbing layer coating solution is applied to the surface of the transparent undercoat layer 12 and dried to form a light absorbing region. (FIG. 5H)
reference). The coating can be performed by a known coating method, but in the case of performing development by heat when forming the light absorbing region, a method in which heat is not applied to the second light absorbing layer 14 during coating is preferable, For example, known coating methods such as a wire coater, a curtain flow coater, an extrusion die coater, an air doctor coater, a bread coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, and a bar coater can be used.

(Light Absorbing Region Forming Step) The light absorbing region forming step is as described above, and light is irradiated from the transparent adhesive layer 15 side (see FIG. 5 (i)) to clean the surface of the second light absorbing layer. A light absorption region is formed by development (see FIG. 5 (j)).

Through the above steps, the transparent beads can be sufficiently buried without damaging the transparent beads due to excessive pressure or the like, and light can be easily and stably diffused isotropically. Further, it is possible to produce a light diffusion film which is excellent in contrast and can obtain an image having an image quality free from roughness.

[0111]

The present invention will be described in detail with reference to the following examples, but the present invention is not limited to the following examples.

Example 1 One surface of PET (transparent substrate) was coated with a water-soluble nylon (“P-70”, manufactured by Toray Industries, Inc.).
) Containing a coating solution using a wire bar,
After drying, a transparent undercoat layer (film thickness after drying was 1 μm) was formed. Transparent beads (made of glass, volume average particle diameter (D ₅₀ ): 6 μm, titanium oxide content: 39% by mass) are densely arranged on the formed transparent undercoat layer, and the transparent undercoat layer is placed at 120 ° C. for 9 minutes. And heated. After the transparent undercoat layer was softened and a part of the transparent beads were embedded in the transparent undercoat layer, the transparent beads were cooled to room temperature and fixed in a state where the transparent beads were embedded in the transparent undercoat layer.

Separately, a first light absorbing layer coating solution was prepared. This coating liquid was prepared by dispersing carbon black in a solution in which an acrylic resin was dissolved in an organic solvent, and no surfactant was used when preparing the coating liquid. This coating liquid was applied on the transparent undercoat layer, and then dried to form a first light absorbing layer. At the time of coating, the coating amount was adjusted in consideration of the volume of the transparent beads, and the thickness after drying was 2 μm. The first light absorbing layer coating solution was repelled from the surface of the transparent beads and was formed only in the gaps between the transparent beads. The surface of the transparent beads was exposed from the first light absorbing layer. Further, a coating solution for a transparent adhesive layer (a solution of an acrylic resin) is applied on the transparent beads,
After drying, a transparent adhesive layer (refractive index: 1.5) was formed.

Next, the transparent substrate was peeled off from the transparent undercoat layer, and a separately prepared coating solution for a second light absorbing layer was applied to the surface of the transparent undercoat layer using a wire bar, and then dried to form a second light absorbing layer. An absorption layer was formed. This coating solution contains a diazonium salt in a microcapsule, a coupler and a base are arranged outside the capsule in a form of being emulsified and dispersed together with other sensitizers, and uses gelatin as a binder. It was what was. The coating amount was adjusted at the time of coating, and the thickness after drying was 2 μm. After that, substantially parallel light is irradiated from the transparent adhesive layer side using a xenon-based exposure device, and the second light absorbing layer is developed by heat treatment at 120 ° C. to form a light absorbing region in the second light absorbing layer. A light diffusion film was produced.

(Evaluation) The graininess (roughness of the obtained image quality) and contrast of the obtained light diffusion film were evaluated by the following methods. Table 1 shows the results.

-Granularity- An image was projected from a rear projector via a light diffusion film, and the resulting image was visually evaluated for halftone granularity (roughness) according to the following criteria. ：: Excellent in graininess (no roughness). ：: Graininess was at a level where there was no practical problem. ×: Inferior in graininess.

-Contrast- An image was projected from a rear projector through a light diffusion film, and the contrast of the obtained image was visually evaluated according to the following criteria. A: The contrast was excellent. ：: The contrast was practically acceptable. X: The contrast was poor.

Example 2 and Comparative Examples 1-4 Examples 1
The thickness of the transparent undercoat layer, the thickness of the first light-absorbing layer, the volume average particle diameter of the beads, and the thickness of the second light-absorbing layer were changed to the values shown in Table 1 in the same manner as described above. The same evaluation as in Example 1 was performed for the diffusion film. In addition, Comparative Examples 1 to
In No. 4, the second light absorbing layer was not provided. Table 1 shows the results.

[0119]

[Table 1]

[0120]

As described above, according to the present invention,
It is possible to provide a light diffusion film which has high transmission efficiency of incident light, has excellent viewing angle characteristics, can provide a high-contrast image, and can further provide an image having an image quality free from roughness. . Further, according to the present invention, it is possible to provide a high-contrast image with high transmission efficiency of incident light, excellent viewing angle characteristics, and further, to provide an image having a rough image quality. A method for efficiently producing a diffusion film can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a configuration of a light diffusion film of the present invention.

FIG. 2 is a schematic sectional view showing another configuration of the light diffusion film of the present invention.

FIG. 3 is a schematic sectional view showing another configuration of the light diffusion film of the present invention.

FIG. 4 is a conceptual diagram for explaining a light absorbing region forming step in the method for manufacturing a light diffusing film of the present invention.

FIG. 5 is a conceptual diagram showing an example of a method for producing a light diffusion film of the present invention.

FIG. 6 is a schematic cross-sectional view showing a configuration of a light diffusion film for improving contrast.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Light-diffusion film 11 1st light absorption layer 12 Transparent undercoat layer 13 Transparent beads 14 2nd light absorption layer 14a Non-light absorption area 14b Light absorption area 15 Transparent adhesive layer 16 Transparent base material

Claims (10)

[Claims] 1. A first light absorbing layer, a transparent undercoat layer disposed on one side of the first light absorbing layer, and a part exposed from the first light absorbing layer and another part exposed from the first light absorbing layer. A light-diffusing film having a plurality of transparent beads embedded and fixed in the first light-absorbing layer and the transparent undercoat layer, wherein the first light-absorbing layer of the transparent undercoat layer is disposed. A light-diffusing film, comprising a second light-absorbing layer having a non-light-absorbing region in each of the regions corresponding to the plurality of transparent beads on the side where the plurality of transparent beads are not provided. 2. The transparent beads according to claim 1, wherein the volume average particle diameter of the transparent beads is 0.1.
The light diffusion film according to claim 1, wherein the thickness of the light diffusion film is 5 to 50 μm. 3. The light diffusion film according to claim 1, wherein the second light absorbing layer is made of a positive photosensitive color developing material. 4. The light-diffusing film according to claim 1, wherein the first light-absorbing layer is made of a negative photosensitive coloring material or a black pigment. 5. The light diffusion film according to claim 1, further comprising a transparent adhesive layer on a side of the first light absorption layer where the transparent undercoat layer is not disposed. 6. The light diffusing film according to claim 1, further comprising a transparent substrate on a side of the second light absorbing layer where the transparent undercoat layer is not disposed. 7. A first light absorbing layer, a transparent undercoat layer disposed on one side of the first light absorbing layer, and a part partially exposed from the first light absorbing layer and another part is exposed. A plurality of transparent beads embedded and fixed in the first light absorbing layer and the transparent undercoat layer; and the plurality of transparent beads on a side of the transparent undercoat layer where the second light absorbing layer is not arranged. And a second light-absorbing layer having a non-light-absorbing region in a region corresponding to the light-diffusing film, comprising irradiating light from the first light-absorbing layer side, exposing and developing, A method for manufacturing a light-diffusing film, comprising a light-absorbing region forming step of forming a light-absorbing region of a second light-absorbing layer. 8. A transparent undercoat layer forming step of forming the transparent undercoat layer on a transparent substrate surface, and embedding transparent beads in the transparent undercoat layer, and applying a first light absorbing layer coating solution. A light absorbing layer forming step, an adhesive layer forming step of forming a transparent adhesive layer on the first light absorbing layer surface, a peeling step of peeling the transparent substrate from the undercoat layer surface, A second light-absorbing layer coating step of applying a light-absorbing layer coating liquid for the second light absorbing layer, wherein the light absorbing region forming step includes:
The method according to claim 7, wherein after the second light absorbing layer coating step, light is irradiated from the transparent adhesive layer side and exposed and developed to form a light absorbing region of the second light absorbing layer. A method for producing the light diffusion film according to the above. 9. The first light-absorbing layer forming step comprises applying a first light-absorbing layer coating solution, exposing and curing to form a first light-absorbing layer. Item 7 or 8
3. The method for producing a light diffusion film according to item 1. 10. The method according to claim 7, wherein in the first light absorbing layer forming step, an excess portion of the first light absorbing layer is removed after forming the first light absorbing layer. 10. The method for producing a light diffusing film according to any one of 9 above.