JPH05302006A - Light-diffusing methacrylate resin - Google Patents

Abstract

PURPOSE:To obtain a methacrylate resin excellent in light-transmitting and light-diffusing properties by dispersing into a methacrylate resin fine spherical particles of a cross-linked polymer having a structural unit derived from a benzene derivative containing more than one polymerizable double bond. CONSTITUTION:100-25% benzene derivative containing at least two polymerizable double bonds in the molecule (e.g. divinylbenzene) is polymerized with 0-75% at least one monomer copolymerizable therewith (e.g. methyl acrylate) to produce fine spherical cross-linked-polymer particles having an average particle diameter of 5-20mum. 0.1-50wt.% the particles are dispersed into a methacrylate resin to thereby produce the title resin. In the particles, the content of particles having particle diameters of 2mum or smaller is preferably below 1wt.%. The obtained resin is suited for use as the material of, e.g. a lamp cover.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light diffusing methacrylic resin suitable for a member for diffusing light, such as a lighting cover, an internally illuminated display, and a diffusing member for a light source of a liquid crystal display.

[0002]

2. Description of the Related Art Light-diffusing methacrylic resin is widely used as a diffuser for various light sources such as a lighting cover. In these applications, it is required to have a high light transmittance and at the same time a high light diffusion property. Particularly in recent years, the need for thinning lighting equipment and liquid crystal display light sources has progressed, and the distance between the light source such as a fluorescent tube and the diffuser has become smaller.

As a conventional means for obtaining a light-diffusing methacrylic resin, for example, barium sulfate or calcium carbonate having a refractive index different from that of the methacrylic resin as a base material (Japanese Patent Laid-Open No. 57-57,570).
-155245), quartz (JP-A-57-5742)
No.), aluminum hydroxide (JP-A-57-157202).
It is generally practiced to disperse inorganic transparent fine particles such as those described in JP-A No. 6-96750 and a method of combining these (Japanese Patent Application Laid-Open No. Sho 5).
7-162743 and 61-4762) have also been proposed.

[0004]

However, when these diffusing agents are used, the property that can be realized, that is, the balance between the light transmittance and the light diffusing property is not sufficient, and when the diffusing property is so high that the light source cannot pass through, The transmittance was low. In addition, in place of the above-mentioned inorganic fine particles, crosslinked fine particles obtained by copolymerizing styrene or substituted styrene and a polyfunctional monomer are dispersed (Japanese Patent Publication No. 39-10515).
No. 46-11834, No. 55-7471), in which crosslinked fine particles obtained by copolymerizing an alkyl (meth) acrylate and a polyfunctional monomer are dispersed (JP-A-59-38).
No. 253) is known, but even when these diffusing agents are used, the balance between the light transmittance and the light diffusing property is not the same as above, or in order to obtain sufficient light diffusing property, However, there is a problem in that a large amount must be added.

The present invention aims to economically provide a light-diffusing methacrylic resin having an excellent balance between light transmittance and light diffusivity, which is an improvement over the conventional techniques.

[0006]

Means for Solving the Problems As a result of earnest studies on a light diffusing agent, the present inventor has found that a benzene derivative containing at least two polymerizable double bonds in a molecule is 100 to 25%.
0.1% of a substantially spherical cross-linked polymer fine particle having an average particle diameter of 5 to 20 μm, which is obtained by polymerizing 0 to 75% of a monomer copolymerizable therewith or a mixture of two or more kinds of monomers. It has been found that a light-diffusing methacrylic resin dispersed by 50% by weight can achieve the above object.

In the present invention, the benzene derivative containing at least two polymerizable double bonds in the molecule is
Examples thereof include, but are not limited to, divinylbenzene, trivinylbenzene, allylstyrene, and phenylene diacrylate. Of these, divinylbenzene is particularly preferable because it is widely used industrially and has a low cost.

The copolymerizable monomers include methyl (meth) acrylate, ethyl (meth) acrylate,
Butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate,
(Meth) acrylic acid esters such as phenyl (meth) acrylate, benzyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate, and diethylaminoethyl (meth) acrylate;
(Meth) acrylic acid, ethylene glycol di (meth)
Polyfunctional (meth) acrylates such as acrylate, trimethylolpropane tri (meth) acrylate, allyl (meth) acrylate, neopentyl glycol di (meth) acrylate, aromatic vinyl monomers such as styrene and α-methylstyrene, phenyl Examples thereof include maleimides such as maleimide and cyclohexylmaleimide, but are not limited thereto. These may be used alone or in combination of two or more as needed.

The average particle size of the crosslinked polymer particles is 5
Is about 20 μm. If the average particle size is smaller than 5 μm, particles having a particle size of 2 μm or less are mixed in more and the transmitted light becomes yellowish. The mixing ratio of the crosslinked polymer fine particles having a particle diameter of 2 μm or less is preferably less than 1% by weight. On the other hand, if the average particle size is larger than 20 μm, when the methacrylic resin is produced by cast polymerization, it is not preferable because the dispersion in the raw material becomes poor and the filtration cannot be performed sufficiently. In the case of manufacturing by extrusion molding or injection molding, uneven appearance is likely to occur in the product appearance, which is also not preferable.

Next, the methacrylic resin of the present invention is mainly composed of methyl methacrylate. Examples of monomers copolymerizable with methyl methacrylate include methyl acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and (meth) acrylic. (Meth) acrylic acid esters such as phenyl acrylate, benzyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate, diethylaminoethyl (meth) acrylate, (meth) acrylic acid, Ethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, allyl (meth) acrylate, neopentyl glycol di (meth) acrylate
Polyfunctional (meth) acrylates such as acrylates, aromatic vinyl monomers such as styrene and α-methylstyrene,
Examples thereof include, but are not limited to, maleimides such as phenylmaleimide and cyclohexylmaleimide, and maleic anhydride. In order to improve the impact resistance of methacrylic resin, a copolymer obtained by grafting a copolymer containing methacrylic acid ester as a main component onto a rubbery copolymer containing acrylate as a main component is added to the above polymer. A dispersion of a polymer is also preferably used.

In the present invention, the blending amount of the crosslinked polymer fine particles with respect to the methacrylic resin varies depending on the required optical characteristics and the thickness at the time of use, but is in the range of 0.1 to 50% by weight. If it is less than 0.1% by weight, sufficient diffusivity cannot be obtained even when the thickness in use is as thick as 20 mm. On the other hand, when it is more than 50% by weight, the mechanical properties of the obtained methacrylic resin are insufficient.

These crosslinked polymer fine particles may be used alone by blending / dispersing them in a methacrylic resin, or may be combined with several kinds of crosslinked polymer fine particles or in combination with known transparent fine particles such as barium sulfate / aluminum hydroxide. Can be used.

Further, in order to enhance the commercial value, it is possible to mix and add dyes and pigments, stabilizers and other additives within the range where the object of the present invention is achieved.

As the method for producing the light diffusing methacrylic resin of the present invention, methyl methacrylate or a monomer mixture containing methyl methacrylate as a main component or a partial polymer thereof is used, and the crosslinked polymer fine particles of the present invention and the Depending on the casting polymerization method in which other additives are mixed and dispersed in accordance with the conditions, and polymerized in a mold, a methyl methacrylate polymer or a copolymer containing methyl methacrylate as a main component, the crosslinked polymer fine particles of the present invention and if necessary. Depending on the method, other additives may be mixed and dispersed to obtain a product by extrusion molding or injection molding.

[0015]

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

The total light transmittance in the examples is
It was measured according to ASTM-D1003-61. As a measure of light diffusivity, the angle dependence of transmitted light intensity when parallel light rays are vertically incident on the methacrylic resin plate used as a sample by using a Murakami Color Research Laboratory variable angle photometer (GP-1R). The property was measured, and the half-value angle of the luminous intensity (the angle at which the transmitted luminous intensity becomes 50 when the transmitted luminous intensity in the direction perpendicular to the sample is 100) was determined. By definition of a perfect diffuser, its half-value angle is 60 degrees, so it can be said that the closer the half-value angle measurement value is to 60 degrees, the better the diffusivity.

For the average particle size, a cumulative weight% histogram of the particle size was prepared from "TA-II type Coulter Counter" manufactured by Coulter Counter, and the particle size corresponding to 50% by weight was taken as the average particle size.

Examples 1 to 4 [Production of fine particles of crosslinked polymer] 50 parts of divinylbenzene,
50 parts of styrene, 0.1 part of 2,2'-azobis- (2,4-dimethylvaleronitrile) as a polymerization initiator, 1 part of water
00 parts and 0.01 part of 70% saponified potassium polyacrylate as a dispersant were placed in a polymerization vessel, and suspension polymerization was carried out at 80 ° C. with stirring. After the polymerization, the polymer was washed, dried, and classified by a wind micron separator to obtain crosslinked polymer fine particles. The average particle size was 8 μm.

[Production of Light-Diffusing Methacrylic Resin Plate] The cross-linked polymer fine particles obtained above were blended in a partial polymer of methyl methacrylate (polymerization rate: 20%) in a ratio shown in Table 1 and sufficiently dispersed. To this mixture, a further release agent was added.
01 parts of dioctyl sulfosuccinate sodium salt and 2,2'-azobis- (2,4) as a polymerization initiator.
-Dimethylvaleronitrile) 0.04 part was added and dissolved, and then degassed and poured into two inorganic glass molds set in advance to have a plate thickness of 2 mm. It was immersed in a warm water bath for 180 minutes and then left in an air bath at 120 ° C. for 120 minutes to complete the polymerization. After cooling, the resin plate was taken out from the mold, and the optical performance was measured and evaluated.

Examples 5-6 [Production of crosslinked polymer fine particles] Crosslinked polymer fine particles having the composition shown in Table 1 were produced in the same manner as in Examples 1 to 4. The average particle size was 8 μm. [Production of Light-Diffusing Methacrylic Resin Plate] 3% by weight of the crosslinked polymer fine particles thus obtained was mixed with a partial polymer of methyl methacrylate (polymerization rate: 20%), and methacrylic resin was cast in the same manner as in Examples 1 to 4. A plate was manufactured and its optical performance was measured and evaluated.

Example 7 3 parts of the crosslinked polymer fine particles produced in Examples 1 to 4 were used for a partial polymer (polymerization rate: 25%) obtained by polymerizing 76 parts of methyl methacrylate, 9 parts of styrene and 15 parts of cyclohexylmaleimide. A methacrylic resin plate was produced in the same manner as in Examples 1 to 4 by blending it in a weight percentage, and the optical performance was measured and evaluated.

Example 8 3% by weight of the crosslinked polymer fine particles obtained in Examples 1 to 4 was mixed with a beaded copolymer composed of 94 parts of methyl methacrylate and 6 parts of methyl acrylate, and sufficiently dispersed. This mixture was extruded with an extruder set at 250 ° C., and molded with a vertical type three calender roll at about 80 ° C. to obtain a plate thickness of 2
A methacrylic resin plate of mm was manufactured, and optical performance was measured and evaluated.

Example 9 1.6% by weight of the crosslinked polymer fine particles obtained in Examples 1 to 4 and 1.2% by weight of aluminum hydroxide having an average particle size of 9 μm were mixed with a partial polymer of methyl methacrylate (polymerization rate: 20%). ) And a methacrylic resin cast plate was manufactured by the same method as in Examples 1 to 4, and the optical performance was measured and evaluated.

Comparative Examples 1 to 4 [Production of Crosslinked Polymer Fine Particles] Crosslinked polymers were produced in the same manner as in Examples 1 to 4 using 5 parts of divinylbenzene and 95 parts of styrene. The average particle size was 8 μm. [Production of Light-Diffusing Methacrylic Resin Plate] The obtained crosslinked polymer fine particles were mixed with a partial polymer of methyl methacrylate (polymerization rate: 20%) at a ratio shown in Table 1, and by the same method as in Examples 1 to 4. A methacrylic resin cast plate was manufactured, and its optical performance was measured and evaluated.

Comparative Examples 5 to 8 [Production of crosslinked polymer fine particles] 15 parts of divinylbenzene,
Crosslinked polymer fine particles were produced in the same manner as in Examples 1 to 4 using 85 parts of styrene. The average particle size was 8 μm. [Production of Light-Diffusing Methacrylic Resin Plate] The obtained crosslinked polymer fine particles were mixed with a partial polymer of methyl methacrylate (polymerization rate: 20%) at a ratio shown in Table 1, and by the same method as in Examples 1 to 4. A methacrylic resin cast plate was manufactured, and its optical performance was measured and evaluated.

Comparative Example 9 A methacrylic resin plate was produced in the same manner as in Example 7 except that the crosslinked polymer fine particles produced in Comparative Examples 1 to 4 were used, and the optical performance was measured and evaluated.

Comparative Example 10 A methacrylic resin plate was produced in the same manner as in Example 8 except that the crosslinked polymer fine particles produced in Comparative Examples 1 to 4 were used, and the optical performance was measured and evaluated.

Comparative Examples 11 to 12 [Production of crosslinked polymer fine particles] Methyl methacrylate 60
Parts, styrene 40 parts, and 1,6-hexanediol dimethacrylate 5 parts were used to obtain crosslinked polymer fine particles in the same manner as in Examples 1 to 4. The average particle size was 5 μm. [Production of Light-Diffusing Methacrylic Resin Plate] This was mixed with a partial polymer of methyl methacrylate (polymerization rate: 20%) at a ratio shown in Table 1 to produce a methacrylic resin cast plate by the same method as in Examples 1 to 4. Then, the optical performance was measured and evaluated.

Comparative Examples 13 to 15 Barium sulfate having an average particle size of 1 μm was added to a partial polymer of methyl methacrylate (polymerization rate: 20%) at a ratio shown in Table 1, and methacrylic acid was prepared in the same manner as in Examples 1 to 4. A resin cast plate was manufactured, and its optical performance was measured and evaluated.

Comparative Examples 16 to 17 Aluminum hydroxide having an average particle size of 9 μm was added to a partial polymer of methyl methacrylate (polymerization rate: 20%) at a ratio shown in Table 1 by the same method as in Examples 1 to 4. , A methacrylic resin cast plate was manufactured, and the optical performance was measured and evaluated.

Examples 10 to 11 [Production of fine particles of crosslinked polymer] 60 parts of divinylbenzene,
Crosslinked polymer fine particles were produced in the same manner as in Examples 1 to 4 using 40 parts of styrene. The average particle size was 5 μm. [Production of Light-Diffusing Methacrylic Resin Plate] The crosslinked polymer fine particles obtained were blended with a partial polymer of methyl methacrylate (polymerization rate: 20%) at a ratio shown in Table 2, and methacrylic acid was prepared in the same manner as in Examples 1 to 4. A resin cast plate was manufactured, and its optical performance was measured and evaluated.

Examples 12 to 13 [Production of fine particles of crosslinked polymer] 60 parts of divinylbenzene,
Crosslinked polymer fine particles were produced in the same manner as in Examples 1 to 4 using 40 parts of styrene. The average particle size was 12 μm. [Production of Light-Diffusing Methacrylic Resin Plate] The crosslinked polymer fine particles obtained were blended with a partial polymer of methyl methacrylate (polymerization rate: 20%) at a ratio shown in Table 2, and methacrylic acid was prepared in the same manner as in Examples 1 to 4. A resin cast plate was manufactured, and its optical performance was measured and evaluated.

Comparative Examples 18 to 19 [Production of Crosslinked Polymer Fine Particles] Crosslinked polymer fine particles were produced in the same manner as in Examples 1 to 4 using 5 parts of divinylbenzene and 95 parts of styrene. The average particle size was 5 μm. [Production of Light-Diffusing Methacrylic Resin Plate] The crosslinked polymer fine particles obtained were blended with a partial polymer of methyl methacrylate (polymerization rate: 20%) at a ratio shown in Table 2, and methacrylic acid was prepared in the same manner as in Examples 1 to 4. A resin cast plate was manufactured, and its optical performance was measured and evaluated.

Comparative Examples 20 to 21 [Production of crosslinked polymer fine particles] Crosslinked polymer fine particles were produced in the same manner as in Examples 1 to 4 using 5 parts of divinylbenzene and 95 parts of styrene. The average particle size was 12 μm. [Production of Light-Diffusing Methacrylic Resin Plate] The crosslinked polymer fine particles obtained were blended with a partial polymer of methyl methacrylate (polymerization rate: 20%) at a ratio shown in Table 2, and methacrylic acid was prepared in the same manner as in Examples 1 to 4. A resin cast plate was manufactured, and its optical performance was measured and evaluated.

Comparative Examples 22 to 23 [Production of crosslinked polymer fine particles] 15 parts of divinylbenzene,
Using 85 parts of styrene as in Examples 1-4,
Crosslinked polymer microparticles were produced. The average particle size was 5 μm. [Production of Light-Diffusing Methacrylic Resin Plate] The crosslinked polymer fine particles obtained were blended with a partial polymer of methyl methacrylate (polymerization rate: 20%) at a ratio shown in Table 1, and methacrylic acid was prepared in the same manner as in Examples 1 to 4. A resin cast plate was manufactured, and its optical performance was measured and evaluated.

Comparative Examples 24 to 25 [Production of fine particles of crosslinked polymer] 15 parts of divinylbenzene,
Using 85 parts of styrene as in Examples 1-4,
Crosslinked polymer microparticles were produced. The average particle size was 12 μm. [Production of Light-Diffusing Methacrylic Resin Plate] The crosslinked polymer fine particles obtained were blended with a partial polymer of methyl methacrylate (polymerization rate: 20%) at a ratio shown in Table 1, and methacrylic acid was prepared in the same manner as in Examples 1 to 4. A resin cast plate was manufactured, and its optical performance was measured and evaluated.

Example 14 [Production of fine particles of crosslinked polymer] 60 parts of divinylbenzene,
Using 40 parts of styrene as in Examples 1-4,
Crosslinked polymer microparticles were produced. The average particle size was 8 μm. [Production of Light-Diffusing Methacrylic Resin Plate] The obtained crosslinked polymer fine particles were blended with a partial polymer of methyl methacrylate (polymerization rate: 20%) in a ratio shown in Table 2 and sufficiently dispersed. To this mixture, 0.01 part of dioctyl sulfosuccinate sodium salt as a release agent and 0.08 part of 2,2'-azobis- (2,4-dimethylvaleronitrile) as a polymerization initiator were further added. After melting, it was degassed and poured into two inorganic glass molds with a plate thickness set to 0.5 mm in advance, the molds were immersed in a warm water bath at 65 ° C for 180 minutes, and then 120 Polymerization was completed by staying in an air bath at ℃ for 120 minutes. After cooling, the resin plate was taken out from the mold, and the optical performance was measured and evaluated.

Example 15 The crosslinked polymer fine particles obtained in Example 14 were blended with a partial polymer of methyl methacrylate (polymerization rate: 20%) in a ratio shown in Table 2 and sufficiently dispersed. This mixture was further added with 0.01 part of dioctyl sulfosuccinate sodium salt as a releasing agent and 2,2'-azobis- as a polymerization initiator.
(2,4-Dimethylvaleronitrile) 0.007 part was added and dissolved, and then degassed and poured into two inorganic glass molds set to have a plate thickness of 10 mm in advance. Was immersed in a warm water bath at 65 ° C. for 240 minutes and then left in an air bath at 120 ° C. for 240 minutes to complete the polymerization. After cooling, the resin plate was taken out from the mold, and the optical performance was measured and evaluated.

Example 16 The crosslinked polymer fine particles obtained in Example 14 were mixed with a partial polymer of methyl methacrylate (polymerization rate: 20%) in a ratio shown in Table 2 and sufficiently dispersed. This mixture was further added with 0.01 part of dioctyl sulfosuccinate sodium salt as a releasing agent and 2,2'-azobis- as a polymerization initiator.
(2,4-Dimethylvaleronitrile) 0.005 part was added and dissolved, and then degassed and poured into two inorganic glass molds set in advance to have a plate thickness of 20 mm. Was immersed in a warm water bath at 50 ° C. for 24 hours and then left in an air bath at 120 ° C. for 240 minutes to complete the polymerization. After cooling, the resin plate was taken out from the mold, and the optical performance was measured and evaluated.

Comparative Examples 26 to 28 Methacrylic resin plates were produced in the same manner as in Examples 14 to 16 except that the crosslinked polymer fine particles produced in Comparative Examples 1 to 4 were used, and the optical performance was measured and evaluated.

Comparative 29 to 31 A methacrylic resin plate was produced in the same manner as in Examples 14 to 16 except that the crosslinked polymer fine particles produced in Comparative Examples 5 to 8 were used, and the optical performance was measured and evaluated.

Examples 17 to 18 [Production of fine particles of crosslinked polymer] 60 parts of divinylbenzene,
Using 40 parts of styrene as in Examples 1-4,
Crosslinked polymer microparticles were produced. The average particle size was 8 μm. [Production of Light-Diffusing Methacrylic Resin Plate] A methacrylic resin plate was produced in the same manner as in Example 8 except that the obtained crosslinked polymer fine particles and barium sulfate having an average particle diameter of 3 μm were used, and the optical performance was improved. It was measured and evaluated.

Examples 19 to 20 [Production of fine particles of crosslinked polymer] Methyl methacrylate 60
Parts, styrene 40 parts, and 1,6-hexanediol dimethacrylate 5 parts were used to obtain crosslinked polymer fine particles in the same manner as in Examples 1 to 4. The average particle size was 8 μm. [Production of Light-Diffusing Methacrylic Resin Plate] A methacrylic resin plate was produced in the same manner as in Example 8 except that the obtained crosslinked polymer fine particles and the crosslinked polymer fine particles produced in Examples 17 to 18 were used. Then, the optical performance was measured and evaluated.

Example 21 To a beaded copolymer consisting of 97 parts of methyl methacrylate and 3 parts of methyl acrylate, 3% by weight of the crosslinked polymer fine particles obtained in Example 6 was added, and further 3% by weight of monoglyceride stearate was added. , 0.01% by weight of ethylene bis-stearyl amide were added and mixed by a V-type tumbler (Kouju Mixwell, Kotobuki Seisakusho Co., Ltd.) for 10 minutes to sufficiently disperse. Then, it was extruded with a twin-screw extruder (PCM-30, manufactured by Ikegai Iron Works Co., Ltd.) at a cylinder temperature of 210 to 240 ° C. and pelletized. The pellets are screw-type injection molding machine (IS-60B, Toshiba Machine Co., Ltd.)
Cylinder temperature 210 ~ 250 ℃, mold temperature 60 ℃
Then, the optical performance of a 100 mm × 100 mm × 2 mm flat plate molded product was measured and evaluated.

The optical characteristics of the methacrylic resin plates obtained in the above Examples and Comparative Examples are shown in Tables 1 to 3 and FIGS. 1 to 3.

In FIG. 1, the horizontal axis represents the total light transmittance and the vertical axis represents the half-value angle of the transmitted light intensity, and the optical characteristics of each example are plotted. Compared with Comparative Examples 1 to 4 and 9 to 12 (above conventional crosslinked polymer fine particles) and Comparative Examples 13 to 17 (inorganic transparent fine particles), the light diffusing methacrylic resins of Examples 1 to 9 and 17 to 21 were It can be seen that the light transmittance and the light diffusivity are good.

In FIG. 2, the horizontal axis represents the amount of crosslinked polymer fine particles blended,
The half-value angle is taken on the vertical axis, and the optical characteristics of the light-diffusing methacrylic resin made of fine particles having an average particle diameter of 8 μm are compared. Comparative Examples 5 to 8 (conventional crosslinked polymer fine particles) are shown in FIG.
As far as it can be seen, the same balance of transmittance and diffusivity as in Examples 1 to 9 is realized. However, as is clear from FIG. 2, the amount of the crosslinked polymer fine particles required to achieve the same optical properties was higher than that of Comparative Examples 5-8 in Examples 1-9.
Is a little over 1/2.

In FIG. 3, the horizontal axis represents the amount of crosslinked polymer fine particles,
The half-value angle is taken on the vertical axis, and the optical characteristics of the light-diffusing methacrylic resin with fine particles having an average particle diameter of 5 and 12 μm are compared. Comparing the use examples of the crosslinked polymer fine particles having the same average particle diameter, it can be seen that the present invention can also obtain high diffusion performance with a smaller compounding amount as compared with the case where the conventional crosslinked polymer fine particles are used.

[0049]

[Table 1]

[0050]

[Table 2]

[0051]

The present invention has the constitution as described in detail above, has a good balance between the light transmittance and the light diffusivity, and requires a small amount of the crosslinked polymer fine particles for that purpose. It has the excellent characteristics of.

[0052]

[Brief description of drawings]

FIG. 1 shows some optical characteristics of Examples and Comparative Examples of the present invention, in which the horizontal axis represents total light transmittance and the vertical axis represents half-value angle of transmitted light intensity.

FIG. 2 shows some optical characteristics of Examples and Comparative Examples of the present invention, in which the horizontal axis represents the amount of crosslinked polymer fine particles blended and the vertical axis represents the half-value angle.

FIG. 3 shows some optical characteristics of Examples and Comparative Examples of the present invention, in which the horizontal axis represents the blending amount of crosslinked polymer fine particles and the vertical axis represents the half-value angle.

Claims (3)

[Claims] 1. A benzene derivative having at least two polymerizable double bonds in the molecule, 100 to 25%, a monomer copolymerizable therewith, or a mixture of two or more monomers.
75% polymerized, substantially spherical average particle size 5 to 2
A light-diffusing methacrylic resin in which 0 to 50% by weight of crosslinked polymer fine particles are dispersed. 2. The light-diffusing methacrylic resin according to claim 1, wherein the benzene derivative containing at least two polymerizable double bonds in the molecule is divinylbenzene. 3. The light diffusion according to claim 1, wherein in the substantially spherical crosslinked polymer fine particles having an average particle diameter of 5 to 20 μm, the proportion of particles having a particle diameter of 2 μm or less is less than 1% by weight. Methacrylic resin.