JP3330269B2 - Diffusion plate for transmission screen - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light diffusing plate used for a transmissive screen used as a screen of a projection television or the like, and more particularly to a light diffusing plate having no see-through phenomenon and having excellent light diffusing properties. And a diffuser for a transmission screen capable of providing a high-quality bright image having high contrast.

[0002]

2. Description of the Related Art In a transmissive screen used in a projection television or the like, a diffusion screen is used so that the brightness and uniformity of the screen can be obtained, and a certain bright image can be observed even when obliquely viewed. The projection light is diffused using a plate. As such a diffusing plate, a diffusing plate such as a resin plate mixed with a diffusing agent or a lenticular lens sheet having a lenticular lens formed on the surface of such a resin plate is used.

[0003] As a diffusing agent used in such a diffusion plate, inorganic particles such as silica particles, alumina particles, calcium carbonate particles, and glass beads, and resin beads such as acrylic resin beads and styrene resin beads are used. It had been. However, in a diffusion plate using such a diffusing agent, when the amount of the diffusing agent added is small, the brightness (gain: G ₀ ) of the screen increases, but a see-through phenomenon in which the light source can be seen through occurs. On the other hand, when the amount of addition increases, such a see-through phenomenon disappears, and although high diffusivity is obtained and the viewing angle is widened, the screen gain and the resolution are reduced. In a transmission screen, it is required that an excellent image without a see-through phenomenon be obtained in addition to a high total light transmittance, a haze value, a light diffusion property and a contrast.

[0004]

To cope with such a demand, Japanese Patent Application Laid-Open No. 1-172801 discloses that light diffusing properties can be reduced without lowering the total light transmittance by using silicone resin beads as a diffusing agent. Diffusion plates that enhance it have been proposed. However, when such a silicone resin bead is added to a methyl methacrylate-based resin plate or the like to form a diffusion plate, the difference in the refractive index between the two results in a luminance with respect to a small change in viewing angle in a high screen gain region. There is a problem that the change becomes large and a see-through phenomenon occurs. On the other hand, expansion using crosslinked polymer beads
In order to improve the light diffusing property of a scattering plate, see Japanese Patent Application Laid-Open No. 1-2699.
No. 02 proposes to use silicone resin beads and crosslinked polymer beads in combination. However, in such a diffusion plate, although the light diffusivity is improved , yellow coloring occurs and the contrast is low, and it is not yet sufficiently satisfactory. Therefore, an object of the present invention is to provide a diffusion plate for a transmission screen that has high total light transmittance and excellent light diffusivity, has no see-through phenomenon, and can provide a high-quality bright image with high contrast. It is in.

[0005]

Means for Solving the Problems In view of the above-mentioned problems of the prior art, the present inventors have made intensive studies on a diffusing agent to be added to a diffusion plate, and as a result, have reached the present invention. That is, the diffusing plate for a transmission screen of the present invention comprises 1 to 25% by weight of light selective functional resin beads containing 0.05 to 20% by weight of neodymium element, and an average particle diameter of 3%.
0.01 to 1% by weight of silicone resin beads
It is characterized by containing.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The light selective functional resin beads used in the present invention selectively absorb light rays in a wavelength range around 580 nm, thereby improving the contrast of a screen and improving antiglare properties and color rendering properties. In this case, resin beads containing a neodymium element in a transparent resin are used. The transparent resin is not particularly limited, but a (meth) acrylic resin such as a methyl methacrylate resin is preferable. The content of the neodymium element in the transparent resin is 0.05 to 20% by weight, preferably 0.1 to 15% by weight. This is because when the content of the neodymium element is less than 0.05% by weight, the contrast cannot be sufficiently increased, and when the content exceeds 20% by weight, the productivity of the photoselective functional resin beads is poor.

The light selective functional resin beads containing the neodymium element include a transparent resin in which a powder of nadium oxide or the like is uniformly dispersed, and a transparent resin to which a neodymium compound is bound or dissolved. Among them, the light selective functional resin beads such as the latter are particularly preferable in terms of the transparency of the beads and the magnitude of light absorption near 580 nm. Photoselective functional resin beads such as the latter, for example, neodymium carboxylate or a double salt obtained from neodymium carboxylate and carboxylic acid,
The polymer can be produced by suspension polymerization of a polymerizable monomer with a polymerizable monomer which can be transparent.

The neodymium carboxylate used may be either polymerizable or non-polymerizable. As neodymium carboxylate having polymerizability,
Neodymium methacrylate, neodymium acrylate, α-
Neodymium chloroacrylate, neodymium α-ethyl methacrylate, neodymium maleate, neodymium fumarate, neodymium itaconate and the like can be mentioned. The non-polymerizable neodymium carboxylate includes propionic acid, n-butyric acid, isobutyric acid, n-valeric acid, isovaleric acid, and n-valeric acid.
-Caproic acid, n-caprylic acid, n-capric acid, α-
Saturated fatty acids such as ethylhexic acid, lauric acid and stearyl acid, oleic acid, linoleic acid, linolenic acid, ricinoleic acid, benzoic acid, phthalic acid, succinic acid, maleic acid, itaconic acid, monoalkyl esters of itaconic acid, naphthenic acid, etc. Unsaturated fatty acids, repcarboxylic acid, oxocarboxylic acids such as acetyl acid, lactic acid, glycolic acid ethyl ether, hydroxycarboxylic acid such as butyl glycolate,
Phosphoric acids such as butyl acid phosphate and ethyl acid phosphate; and neodymium salts such as aliphatic and aromatic sulfonic acids. These neodymium carboxylate may be used alone or in combination of two or more, and a polymerizable one and a non-polymerizable one may also be used in combination.

Since such neodymium carboxylate is hardly soluble in a polymerizable monomer, it is reacted with a carboxylic acid as needed to impart solubility to the polymerizable monomer as a double salt. As the carboxylic acid for this,
Methacrylic acid, polymerizable unsaturated carboxylic acids such as acrylic acid, propionic acid, isobutyric acid, n-butyric acid, caproic acid,
Examples include aliphatic carboxylic acids such as caprylic acid, capric acid, 2-ethylhexanoic acid, stearic acid, octanoic acid, and naphthenic acid. These carboxylic acids can be used alone or
More than one species can be used in combination. The amount of the carboxylic acid used is preferably in the range of 10 to 40% by weight, when the total amount of neodymium carboxylate and carboxylic acid is 100% by weight. This is because when the amount of the carboxylic acid exceeds 40% by weight, the content of the neodymium element in the photoselective resin beads tends to decrease, and the mechanical and thermal properties of the resin beads tend to decrease. It is because there is.

Further, in order to further improve the solubility of neodymium carboxylate, unsaturated alcohols such as α-hydroxyethyl acrylate and α-hydroxyethyl methacrylate, saturated aliphatic alcohols such as propyl alcohol and cyclohexyl alcohol, ethylene glycol, Alcohols such as polyhydric alcohols such as diethylene glycol and propylene glycol can be used in combination with the above carboxylic acids. In this case, the amount of the alcohol used is in the range of 10 to 40% by weight in the same manner as described above in terms of the total amount with the carboxylic acid.

As the polymerizable monomer which can make the polymer transparent, there are (meth) acrylic acid ester and styrene. Examples of the (meth) acrylate include alkyl (meth) acrylates such as methyl (meth) acrylate and ethyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate,
Tetrahydrofuryl (meth) acrylate, phenyl (meth) acrylate, allyl (meth) acrylate, (meth)
Methallyl acrylate, β-naphthyl (meth) acrylate, β-aminoethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetramethylene Glycol di (meth) acrylate, polyethylene glycol di (meth)
Acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol tetra (meth) acrylate, trimethylolpropane tri (meth) Acrylates and their halogen-substituted (meth) acrylates. These polymerizable monomers can be used alone or in combination of two or more. When a polyfunctional acrylate such as ethylene glycol diacrylate, diethylene glycol diacrylate, or diethylene glycol dimethacrylate is used as the polymerizable monomer, crosslinked resin beads can be used. A copolymerizable monomer can be used in combination with the polymerizable monomer as long as the transparency of the obtained resin beads is not impaired. Examples of such a copolymerized monomer include vinyl acetate, acrylonitrile, methacrylonitrile, and the like.

The neodymium carboxylate and the carboxylic acid as described above are added to the polymerizable monomer, and are added at room temperature or at room temperature.
By performing stirring for about 0.5 to 5 hours while heating at a temperature of not more than 00 ° C., a double salt of neodymium carboxylate and carboxylic acid is produced and is in a state of being dissolved in the polymerizable monomer. As a result, a polymerizable mixed solution in which neodymium carboxylate, carboxylic acid and the polymerizable monomer are uniformly mixed is obtained. The obtained polymerizable mixed solution and the polymerization initiator are suspended in an aqueous phase, and suspension polymerization is performed at 30 to 90 ° C. for about 1 to 10 hours. After completion of the suspension polymerization, the polymer particles obtained by a conventional method are dehydrated, washed with water, and dried, whereby transparent spherical light-selective functional resin beads can be obtained.
If necessary, the photoselective functional resin beads can be classified into a desired particle size range using a classifier.

In this case, the polymerization initiator used is α, α′-azobisisobutylnitrile, α, α ′
Azobis (2,4-dimethylvaleronitrile), α,
Examples include azobis-based initiators such as α'-azobis (2,4-dimethyl-4-methoxyvaleronitrile), and these can be used alone or in combination of two or more. The amount of the polymerizable component used in the polymerizable mixed solution is 10
It is in the range of 0.001 to 1 part by weight with respect to 0 part by weight.
For the stabilization of the suspended particles, protective colloids such as polyvinyl alcohol, carboxymethylcellulose, sodium polyacrylate, alginic acid, and gelatin can be used as appropriate.

The shape, refractive index and the like of the photoselective functional resin beads obtained by such a production method can be appropriately changed by changing the kind and mixing ratio of the raw material monomers, polymerization conditions and the like. . In the present invention, the particle diameter of the photoselective functional resin beads is not particularly limited, but is preferably in the range of 2 to 30 μm in average particle diameter. If the average particle size is less than 2 μm, scattered light is likely to be generated and the diffusion plate tends to be colored yellow. Conversely, if it exceeds 30 μm, the production of the diffusion plate becomes difficult or the mechanical strength of the diffusion plate decreases. This is because there is a tendency to do so.

The silicone resin beads used in the present invention diffuse the projection light as a light diffusing agent to increase the viewing angle of the screen, and the silicone resin constituting the beads is not particularly limited. No, but with a structure having a polysiloxane bond in which an organic group is directly bonded to a silicon atom, a structure in which an organic group is directly bonded to a silicon atom, and the remaining bonds are directly bonded to oxygen, and the silicon atom and oxygen form a repeating siloxane bond. Solid at room temperature or higher is preferred. Silicone resin beads made of such a silicone resin exhibit intermediate properties between glass-like inorganic properties and organic properties due to organic groups. Particularly preferably, as shown in FIG. 1, a silicone resin having a network structure in which siloxane bonds are three-dimensionally extended, and having a structure in which one organic group R is bonded to a silicon atom, is used as a silicone resin bead. It is excellent in dispersibility in a transparent resin and a polymerizable monomer constituting a diffusion plate. As the organic group directly bonded to the silicon atom, those having an affinity for the transparent resin and the monomer constituting the diffusion plate of the present invention, for example, an alkane group such as a methyl group, an ethyl group, a propyl group, and a butyl group; Examples thereof include a carboxyl group, a carbonyl group, an ester group, and an ether group, and among them, a methyl group is preferable.

Such a silicone resin bead is produced, for example, by using a hydrolyzable silane having three functional groups as a raw material and performing a hydrolysis and polycondensation reaction to form a silicone resin having a three-dimensional network structure as shown in FIG. Beads can be manufactured. In this hydrolysis and polycondensation reaction step, the particle size of the silicone resin beads depends on the type of the functional group of the hydrolyzable silane used, the type of the organic group, the type and amount of the hydrolysis catalyst, and other production conditions. , Shape, refractive index and the like can be changed, and by controlling these, desired silicone resin beads can be produced. In the present invention, the average particle diameter of the silicone resin beads needs to be 3 to 6 μm, preferably 4 to 5 μm. This is because, when the average particle diameter is less than 3 μm, the luminance change becomes large with respect to a small viewing angle change in a region where the screen gain is high, and the occurrence of a see-through phenomenon becomes remarkable.
Conversely, when the thickness exceeds 6 μm, the light diffusivity decreases.

The diffusion plate for a transmission screen of the present invention comprises 1 to 25% by weight of the above-mentioned light selective functional resin beads.
And 0.01 to 1% by weight of silicone resin beads. The addition of a small amount of silicone resin beads imparts light diffusing property to the screen, and the see-through phenomenon of the screen is caused by the light selective functional resin beads. Can be suppressed, and the contrast can be improved. 1% by weight photoselective resin beads
If the amount is less than 25%, the see-through phenomenon tends to occur on the screen, and the contrast of the screen decreases. If the amount exceeds 25% by weight, the production of the diffusion plate becomes difficult, Is preferably in the range of 2 to 15% by weight, and more preferably in the range of 3 to 10% by weight. On the other hand, if the content of the silicone resin beads is less than 0.01% by weight, sufficient light diffusing properties cannot be imparted to the screen, and the viewing angle becomes narrow. This is because the gain of the screen is significantly reduced, preferably in the range of 0.01 to 0.7% by weight,
More preferably, it is in the range of 0.01 to 0.5% by weight.

The transmission screen diffusion plate of the present invention is
It is composed of a transparent resin such as (meth) acrylic resin, polycarbonate resin, vinyl chloride resin, polystyrene resin and polyester resin. Above all, a methacrylic resin containing methyl methacrylate as a main component is preferable. Although the thickness varies depending on the size of the screen, it is usually about 5 mm or less, and preferably 3 mm or less in consideration of improvement in resolution. Further, in the present invention, the diffusion plate for a transmission screen can be used as a single-plate diffusion plate containing light-selective functional resin beads and silicone resin beads,
It can also be used as a diffusive lens sheet in which a lens pattern such as a lenticular lens is formed on the surface of a plate. Examples of the formed lens pattern include a lenticular lens sheet having a lenticular lens formed on one or both surfaces, a Fresnel lens sheet having a Fresnel lens formed on one surface, and a lenticular lens formed on one surface and a Fresnel lens formed on the other surface. No.

The diffusion plate for a transmission screen of the present invention is obtained by adding and dispersing a light selective functional resin bead and a silicone resin bead to a transparent resin pellet, and performing extrusion molding, injection molding, and the like.
It can be formed into a desired shape by a molding method such as calendering. When an acrylic resin such as polymethyl methacrylate is used as the transparent resin, photo-selective resin beads and silicone resin beads are added to the acrylate partial polymer, and the resulting mixture is injected into a mold to perform polymerization. It can also be formed by a method. When used as a diffusible lens sheet, a lens pattern can be transferred to a plate-like body formed by the above method by a hot press method or the like.

[0020]

The present invention will be specifically described below with reference to examples. Preparation of Photoselective Functional Resin Beads 34% by weight of neodymium methacrylate, 42% by weight of methyl methacrylate, 15% by weight of lauric acid, and 9% by weight of propylene glycol are heated to 65 ° C. with stirring and dissolved over about 2 hours. Thus, a polymerizable mixed solution was obtained. Then, a stirrer,
100 parts by weight of the above polymerizable mixed solution, 0.5 parts by weight of azobisisobutylnitrile, 3 parts by weight of polyvinyl alcohol, and 800 parts by weight of water are charged into an autoclave container equipped with a nitrogen gas inlet, and stirred at high speed. The atmosphere was replaced with nitrogen gas. Thereafter, polymerization was performed at 75 ° C. for 4 hours, and then at 90 ° C. for 1 hour. After polymerization, dehydration,
After washing with water and drying, transparent spherical resin beads were obtained. The obtained resin beads were classified using a wind micro separator to produce two types of photoselective functional resin beads having an average particle diameter of 5 μm and 20 μm. The content of the neodymium element in the resin of the obtained photoselective functional resin beads was 12%.
% By weight.

Measurement of Screen Gain One surface of the diffuser was illuminated at a constant illuminance, and the luminance on the opposite surface was measured. The ratio of the illuminance to the luminance was defined as the screen gain. Evaluation of Contrast, See-Through, and Light Diffusion A diffuser plate was attached to a 45-inch projection television (45P-B2-B manufactured by Mitsubishi Electric), observed from a position 3 m away from the projection television, and visually evaluated according to the following criteria. . Contrast ：: Good contrast. X: The contrast is poor. See-through ：: No see-through phenomenon is observed. X: The see-through phenomenon is observed. Light diffusivity ：: Wide viewing angle. X: The viewing angle is narrow.

EXAMPLE 1 100 parts by weight of a mixed solution of a partial polymer of methyl methacrylate (polymerization ratio: 20%) and a copolymerized monomer were mixed with α, α'-azobis- (2,4-dimethylvaleronitrile) as a polymerization catalyst. 0.04 parts by weight and 0.005 parts by weight of dioctyl sulfosuccinate sodium salt were added. Next, 6% by weight of neodymium-containing methacrylic resin beads having an average particle diameter of 5 μm obtained in the above Production Example, and an average particle diameter of 4.
0.2% by weight of 5 μm silicone resin beads (Tospearl 145 manufactured by Toshiba Silicone Co., Ltd., having a polysiloxane bond in which a methyl group is directly bonded to a silicon atom) were added, mixed, and degassed. Then, it is poured into a mold composed of a tempered glass and a soft vinyl chloride gasket whose thickness is set to 3 mm in advance, and is poured into 70 ° warm water.
The polymerization was completed by immersion for 30 minutes and left in an air bath at 130 ° C. for 80 minutes to remove from the mold to obtain a diffusion plate.
The screen gain of the obtained diffusion plate was measured, and the results are shown in Table 1. Further, the contrast, see-through and light diffusing properties when used as a diffusion plate for a transmission screen were evaluated, and the results are shown in Table 1.

Example 2 100 parts by weight of a mixture of a partial polymer of methyl methacrylate (polymerization ratio: 20%) and a copolymerized monomer were mixed with α, α'-azobis- (2,4-dimethylvaleronitrile) as a polymerization catalyst. 0.04 parts by weight and 0.005 parts by weight of dioctyl sulfosuccinate sodium salt were added. Next, 5% by weight of neodymium-containing methacrylic resin beads having an average particle diameter of 20 μm obtained in the above production example and silicone resin beads having an average particle diameter of 4.5 μm (Tospearl 145 manufactured by Toshiba Silicone Co., Ltd .; 0.15% by weight of a structure having a polysiloxane bond) was added, mixed, and deaerated. Then, it is poured into a mold composed of a tempered glass and a soft vinyl chloride gasket whose thickness is set to 3 mm in advance, immersed in 70 ° C warm water for 80 minutes, and further placed in a 130 ° C air bath. For 80 minutes to complete the polymerization, and then removed from the mold to obtain a diffusion plate. The screen gain of the obtained diffusion plate was measured, and the results are shown in Table 1. Further, the contrast, see-through and light diffusing properties when used as a diffusion plate for a transmission screen were evaluated, and the results are shown in Table 1.

Example 3 To 100 parts by weight of a mixture of a partial polymer of methyl methacrylate (polymerization ratio: 20%) and a copolymerized monomer, α, α'-azobis- (2,4-dimethylvaleronitrile) was used as a polymerization catalyst. 0.04 parts by weight and 0.005 parts by weight of dioctyl sulfosuccinate sodium salt were added. Next, 5% by weight of neodymium-containing methacrylic resin beads having an average particle diameter of 20 μm obtained in the above Production Example,
μm silicone resin beads (Toray's Trefil R9
35, a structure having a polysiloxane bond in which a methyl group is directly bonded to a silicon atom) 0.16% by weight is added and mixed,
Degassed. Then, it is poured into a mold composed of a tempered glass and a soft vinyl chloride gasket whose thickness is set to 3 mm in advance, immersed in 70 ° C warm water for 80 minutes, and further placed in a 130 ° C air bath. For 80 minutes to complete the polymerization, and then removed from the mold to obtain a diffusion plate. The screen gain of the obtained diffusion plate was measured, and the results are shown in Table 1. Further, the contrast, see-through and light diffusing properties when used as a diffusion plate for a transmission screen were evaluated, and the results are shown in Table 1.

Comparative Examples 1 to 5 Diffusion plates were obtained in the same manner as in Example 1 except that the compounding amount of the methacrylic resin containing nadium, the average particle size and the compounding amount of the silicone resin beads were as shown in Table 1. . The screen gain of the obtained diffusion plate was measured, and the results are shown in Table 1. Further, the contrast, see-through and light diffusing properties when used as a diffusion plate for a transmission screen were evaluated, and the results are shown in Table 1.

[0026]

[Table 1]

As is clear from Table 1, in Examples 1 to 3 using the transmission type diffusion plate for a transmission screen of the present invention, all of the images had no see-through phenomenon and were bright images excellent in contrast and light diffusion. there were. On the other hand, Comparative Example 1 containing no neodymium-containing methacrylic resin beads was used.
However, although the light diffusion property was excellent, a see-through phenomenon occurred and the contrast was poor. In Comparative Example 1 in which the content of the neodymium-containing methacrylic resin beads was small, there was no see-through phenomenon, and although the light diffusing property was excellent, the contrast was poor. In Comparative Example 3 in which the average particle diameter of the silicone resin beads is large,
Although there was no see-through phenomenon and the contrast was excellent, the light diffusing property was poor and the viewing angle was narrow. In Comparative Example 4 in which the average particle diameter of the silicone resin beads is small,
Although the contrast and the light diffusion property were excellent, the occurrence of a see-through phenomenon was observed. In Comparative Example 5 having a large content of silicone resin beads, there was no see-through phenomenon,
Although excellent in contrast and light diffusion, the screen gain was extremely reduced and only very dark images were obtained.

[0028]

According to the present invention, a diffusion plate for a transmission screen is provided.
By using a combination of specific light selective functional resin beads and silicone resin beads, it has no see-through phenomenon, has excellent light diffusion properties, and can obtain high-quality bright images with high contrast and high-definition screens such as projection TVs It is possible to provide a transmission screen used as a screen.

[Brief description of the drawings]

FIG. 1 is a model diagram showing a molecular structure of a preferred silicone resin of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03B 21/62 G02B 5/02

Claims (1)

(57) [Claims] 1. An element containing 0.05 to 20% by weight of neodymium.
1 to 25% by weight of the light selective functional resin beads to be contained, and 0.01 to 5% of silicone resin beads having an average particle diameter of 3 to 6 μm.
A diffusion plate for a transmission screen, characterized in that the diffusion plate contains -1% by weight.