JP3306987B2 - Light-diffusing methacrylic resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for a lighting cover, a diffusion plate of a display, a signboard, and the like. The present invention relates to a light-diffusing methacrylic resin for diffusing and transmitting incident light.

[0002]

2. Description of the Related Art Conventionally, as materials for lighting covers, light diffusion plates for transmissive displays, and signboards, transparent resins such as acrylic resins, styrenic resins, polycarbonate resins, and vinyl chloride resins have been used as organic and inorganic materials. A light diffusing plate in which a light diffusing agent is dispersed is widely used. Examples of such a light diffusing agent include particles of an acrylic resin or a styrene resin having a crosslinked structure, and inorganic fine particles such as barium sulfate, calcium carbonate, aluminum hydroxide, silicon dioxide, titanium oxide, and calcium fluoride.

[0003] However, these light-diffusing resin compositions and their plates have mainly aimed at diffusing light, but recently, light is effectively used as a light diffusion plate for lighting covers and various displays. It is desired. That is,
It has been demanded that the light be sufficiently diffused in a predetermined direction and that the light source is not transparent. In response to this demand, there is a proposal for a light-diffusing resin composition or plate mixed with silicon resin fine particles.

Japanese Patent Application Laid-Open No. 1-172801 discloses that a silicone resin particle having an average particle size of 0.3 to 10 μm comprising a polysiloxane bond in which a methyl group is directly bonded as an organic group having an affinity for a monomer is used for a transparent resin. A light transmitting light diffusing plate in which 1 to 50 wt% is mixed and dispersed is disclosed. JP 3-2077
No. 43 discloses that 0.1 to 10 parts by weight of a silicon resin particle having a particle size of 0.5 to 20 μm, which is made of trifunctional siloxane called polymethylsilsesoxane, is dispersed in 100 parts by weight of a methacrylic resin. A methacrylic resin molded article having excellent light transmittance and light diffusion properties is shown. JP-A-3-
No. 294348 discloses that polymethylsilsesquies having a particle size distribution of 1 μm to 30 μm, a weight average particle size of 3 μm to 6 μm, and a content of 2 μm or less of 35% by weight or less are added to 100 parts by weight of a methyl methacrylate resin. Oxane-based resin is added to
The light-diffusing methacrylic resin composition dispersed in 5 to 5 parts by weight is shown. Further, Japanese Patent Application Laid-Open No. 5-39401 discloses that a silicone resin having a phenyl group introduced therein is 0.1 to 20% by weight.
A light diffusible methacrylic resin composition is disclosed.

[0005]

The silicone resin described in Japanese Patent Application Laid-Open No. 1-172801 is a trifunctional siloxane alone type, and although a methyl group is introduced into the particle surface layer, the silicone resin is not compatible with a matrix resin. Affinity is not always sufficient. Since the silicone resin particles described in JP-A-3-207743 have a strong three-dimensional structure, they have properties similar to those of the inorganic particles and have low affinity with the transparent resin. Therefore, the impact strength of the resin composition is reduced.
Further, in a so-called extrusion molding or injection molding in which a transparent resin and the particles are melt-kneaded and molded, since the affinity is low, an unstable molded state and a heterogeneous molded product are easily formed. The silicone resins described in JP-A-3-294348 and JP-A-5-39401 also do not have good affinity with the transparent resin.

Accordingly, the present invention provides a light-diffusing methacrylic resin composition which does not decrease the impact resistance of the resin composition due to the coexistence of a light-diffusing agent and has good molding stability. .

[0007]

SUMMARY OF THE INVENTION The present invention is, against the methyl methacrylate polymer 100 parts by weight, has a backbone consisting of difunctional siloxane units and trifunctional siloxane units, surface alkenyl group, an alkynyl group, an ether Group, acyl
Group, carboxy group, ester group, cyano group, cyanato group
Or have a glycidyl group, weight average particle diameter of 0.5 to 10
there is provided a comprising from 0.1 to 10 parts by weight μm der Ru silicone resin light diffusing methacrylic resin composition.

[0008] The methyl methacrylate polymer used in the present invention refers to a methyl methacrylate homopolymer or a copolymer containing methyl methacrylate in an amount of 50% by weight or more and methyl methacrylate and a copolymerizable monomer such as ethyl methacrylate.
Methacrylates such as butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, acrylic acid Cyclohexyl, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, acrylic acid 2
-Acrylates such as hydroxyethyl, methacrylic acid, unsaturated acids such as acrylic acid, styrene,
Copolymers with α-methylstyrene, acrylonitrile, methacrylonitrile, maleic anhydride, phenylmaleimide, cyclohexylmaleimide, and the like, but are not limited thereto. Further, it may further contain an elastomer component such as polybutadiene, butadiene / butyl acrylate copolymer, or polybutyl acrylate copolymer, a glutaric anhydride unit, or a glutarimide unit.

The silicone resin of the present invention comprises a skeleton of a bifunctional siloxane unit represented by the chemical formula 1 and a trifunctional siloxane unit represented by the chemical formula 2, and an organic functional group is present on the surface of the particle. Things.

[0010]

Embedded image In the formula, R ¹ and R ² are each an organic group.

[0011]

Embedded image In the formula, R ³ is an organic group.

The proportion of the bifunctional siloxane unit in the skeleton constituting the silicone resin of the present invention is 30 to 95% by weight, preferably 40 to 70% by weight. The larger the ratio of the bifunctional siloxane units, the lower the glass transition temperature (Tg) of the silicone resin and the lower the refractive index.

The trifunctional siloxane unit accounts for 5 to 70% by weight, preferably 30 to 60% by weight, of the siloxane unit constituting the silicone resin. The trifunctional siloxane unit makes the silicone resin have a crosslinked structure. or,
Increase the refractive index of the silicone resin.

R ¹ , R ² , and R in Chemical Formula ^1
3 is an organic group, and among them, a hydrocarbon group having 1 to 20 carbon atoms is generally used. Specifically, methyl, ethyl, propyl, isopropyl, butyl, hexyl, dodecyl; phenyl, benzyl, tolyl,
A naphthyl group; and an organic functional group described below. Aromatic hydrocarbon groups have higher heat resistance, and the silicone resin has a higher refractive index.

The silicone resin of the present invention can be prepared by a known method. First, the skeleton is co-hydrolyzed with difunctional and trifunctional chlorosilanes or alkoxysilanes as described in, for example, "Synthesis and Application of Organosilicon Polymer" (November 30, 1989, published by CMC Corporation). And a method by co-condensation. R ¹ , R ² and R ³ can be determined by selecting an organic group directly bonded to Si of the chlorosilane or alkoxysilane used at this time.

The ratio of the bifunctional siloxane unit to the trifunctional siloxane unit may be selected depending on the desired Tg and refractive index of the silicone resin. The Tg of the silicone resin is
-50 ° C to -200 ° C is suitable. It is suitable that the difference in refractive index from the methyl methacrylate polymer is 0.03 to 0.1, that is, 1.39 to 1.46.

The organic functional group present on the surface of the silicone resin of the present invention is one that develops an affinity between the silicone resin and the methyl methacrylate-based polymer. alkenyl groups such as allyl group; ethynyl group, an alkynyl group such as propargyl group; methoxy group, an ethoxy group, ether such as phenoxy group
Group; a carboxy group; a formyl group, an acetyl group, a benzoyl group, an acryloyl group, reed Le group such as a methacryloyl group acetoxy group, methacryloyloxy group, acryloyloxy group, a methoxycarbonyl group, ester le as ethoxycarbonyl Group ; cyano group, cyanato
Group, and etc. glycidyl group. Among them, alkenyl
Group, an alkynyl group, ether group, reed group, Este Le
Groups and glycidyl groups are preferred because the coloring of the resin composition is small as well as the functionality.

The content of the organic functional group is 0.05 to 10% by weight based on the whole silicone resin. Among them, 0.5 to 10% by weight is preferable.

There are known methods for causing an organic functional group to be present on the surface of the silicone resin. For example, when forming the silicon resin skeleton described above, a material in which R ¹ , R ² , and R ³ of chlorosilane as a raw material and alkoxysilane have the organic functional group is selected. Alternatively, using the method described in “Synthesis and Application of Organosilicon Polymer”, a skeleton of the silicon resin is formed, and then a hydrocarbon group on the surface is chlorinated. There is a method of reacting with a reagent.

The particle size of the silicone resin is 0.5 to 10 μm in weight average particle size. Especially, 1-5 micrometers is preferable. When the particle size is 0.5 μm or less, the light is difficult to diffuse because the particle size is smaller than the wavelength of light. If it exceeds 10 μm, the transmitted light decreases, the light diffusion performance decreases, and the impact resistance of the resin composition also decreases. The narrower the particle size distribution, the better.

In any case, the silicone resin is commercially available. Those having a vinyl group are DY33-708 of Toray Dow Corning Silicone Co., Ltd., DY33-719 having a methacryloyl group, E-601 having a glycidyl group, X-ray of Shin-Etsu Chemical Co., Ltd.
52-805K, and so on. Among these, a desired Tg, a refractive index and the like are selected in addition to the particle size and the organic functional group.

The amount of silicone resin is methyl methacrylate
0.1 to 10 parts by weight per 100 parts by weight of the polymer .
Among them, 1 to 7 parts by weight is preferable. If the amount is less than 0.1 part by weight, a sufficient light diffusion effect cannot be obtained. Also, 1
If the amount is more than 0 parts by weight, the impact resistance of the obtained resin composition decreases, and the light transmittance also decreases.

In order to form the light-diffusible methacrylic resin composition of the present invention from the methyl methacrylate polymer and the silicone resin, the two are mixed by a Henschel mixer or the like, and are melt-kneaded by an extruder or an injection molding machine. There are well-known methods to do this.
In addition, there is a method in which the silicone resin is mixed with a syrup containing a monomer constituting the methyl methacrylate weight body and a partial polymer thereof, followed by cast polymerization and suspension polymerization. In the method of melt-kneading, the two can be smoothly and homogeneously obtained because of their good affinity. In the method of polymerizing a mixture with a monomer or syrup, a part of the organic functional groups on the surface of the silicone resin is combined with a part of the polymer, and a more excellent impact resistance is obtained.

The resin composition of the present invention may further contain other light diffusing agents such as titanium oxide, barium sulfate, calcium carbonate, aluminum hydroxide, talc, mica, glass beads, crosslinked acrylic beads, and crosslinked styrene. It is also possible to use a small amount of a silicone resin based on beads or ordinary trifunctional siloxane units.

[0025]

The light-diffusing methacrylic resin composition of the present invention not only has good light transmission and light diffusion properties, but also has the strength of the resin composition caused by mixing solid particles. In particular, the impact resistance is hardly reduced, and the moldability is good. The resin composition can be formed into a plate, a sheet, or various molded products having good light diffusing properties.

[0026]

The present invention will be described in more detail with reference to the following examples.
As will be apparent, the invention is not limited by these examples.
Not. The evaluation method is as follows. -Total light transmittance (Tt); in accordance with ASTM D1003-61,
Poick integrating sphere haze meter (SEP-
HS-30D). -Transmitted light intensity at a transmission angle of 0 ° due to vertically incident light (I₀),
Transmitted light intensity at a transmission angle of 5 ° due to vertically incident light (I_Five)as well as
Transmitted light intensity (I ₇₀)
Automatic variable angle photometer GP-1R manufactured by Murakami Color Research Laboratory Co., Ltd.
Measured using I ₀/ I_FiveIs concealment and I₇₀The wide angle side
Diffusivity was assumed.・ Surface impact strength: DuPont drop impact in accordance with JIS K5400
Using a test machine (manufactured by Yasuda Seiki Seisakusho), from sheet molded products
Total of 1 sheet of 50mm x 50mm x 2mm sheet
0 cards in 1/8 inch shooting type and 1/4 inch cradle
Set and drop 300g weight from 10cm height
The number of broken pieces is shown.

Examples 1 and 2 and Comparative Example 1 100 parts by weight of methacrylic resin beads (SUMIPEX EX, manufactured by Sumitomo Chemical Co., Ltd.) and about 1.
Silicon resin having 3% (DY33-708, manufactured by Dow Corning Toray Silicone Co., Ltd., average particle size 2 μm, Tg-120
C. and a refractive index of 1.419) in a Henschel mixer in an amount shown in Table 1 and then extruder (single screw, screw diameter 40).
mm, manufactured by Tanabe Plastics Co., Ltd.), the molten resin sheet was extruded at a resin temperature of 265 ° C. at the outlet of the T-die, and processed into a sheet having a thickness of 2 mm and a width of 26 cm through three polishing rolls. Table 1 shows the evaluation results of the obtained sheets.

[0028]

[Table 1]

Examples 3 to 6 and Comparative Example 2 100 parts by weight of methacrylic resin beads and a silicone resin having about 4.0% methacryloyloxy groups on the surface (DY33)
-719, manufactured by Toray Dow Corning Silicone Co., Ltd., average particle size 2 μm, Tg-118 ° C, refractive index 1.419) [Table 2]
The procedure was performed in the same manner as in Example 1 except that
A thick sheet was obtained. Table 2 shows the evaluation results of the obtained sheets.

Examples 7 and 8 Silicon resin having 100 parts by weight of methacrylic resin beads and about 2.1% of glycidyl groups on the surface (X-52-805K, manufactured by Shin-Etsu Chemical Co., Ltd., average particle size 4 μm, refraction) Rate 1.43
5, Tg-135 ° C.) and the amount shown in Table 2 were mixed with a Henschel mixer, and then pelletized with an extruder (screw diameter: 20 mm, manufactured by Toyo Seiki Co., Ltd.). ) M-140SJ manufactured by Meiki Seisakusho Co., Ltd.) was molded under the conditions of a molding temperature of 220 to 260 ° C. and a mold temperature of 55 ° C. to obtain a flat plate having a thickness of 2 mm. Table 2 shows the evaluation results of the obtained sheets.

Comparative Example 3 100 parts by weight of methacrylic resin beads and a silicon resin having a methyl group on the surface (KMP-594, manufactured by Shin-Etsu Chemical Co., Ltd., average particle diameter 4 μm, refractive index 1.435, Tg) −
137 ° C.) was mixed in the amount shown in Table 2 with a Henschel mixer, and the same operation as in Example 7 was performed. Table 2 shows the evaluation results.

Comparative Examples 4 to 7 100 parts by weight of methacrylic resin beads, calcium carbonate, polymethylsilsesquioxane-based silicone resin (Tospearl 145, manufactured by Toshiba Silicone Co., Ltd., average particle size 4.5 μm, refractive index 1.430) ) Was mixed with the amount shown in Table 2 using a Henschel mixer, and the same operation as in Example 1 was performed. Table 2 shows the evaluation results of the obtained sheets.

[0033]

[Table 2]

Examples 9 and 10 0.1 part by weight of azobisisobutyronitrile and 100 parts by weight of silicone resin and DY in 100 parts of a partial polymer (syrup) of methyl methacrylate containing 20% by weight of solids
33-719, followed by removal of dissolved air under reduced pressure,
This was poured into a cell formed by two pieces of tempered glass at 2 mm intervals. Heat polymerization was performed at 70 ° C. for 3 hours and at 120 ° C. for 1 hour to obtain a sheet having a thickness of 2 mm.
Table 3 shows the evaluation results of the obtained sheets.

Comparative Example 8 The same procedure as in Example 9 was carried out except that no silicone resin was added. Table 3 shows the results.

Comparative Example 9 In place of the silicone resin in Example 9, a phenyl group-containing silicone resin (Trefle E-603 Toray Industries, Inc. Silicone)
(Average particle size 5 μm, refractive index 1.422, Tg-139 ° C.)
Was carried out in the same manner except that the amounts shown in Table 3 were used. Table 3 shows the evaluation results.

[0037]

[Table 3]

Claims (1)

(57) [Claims] 1. A against the methyl methacrylate-based polymer 100 parts by weight, has a backbone consisting of difunctional siloxane units and trifunctional siloxane units, surface alkenyl group, Arukini
Group, ether group, acyl group, carboxy group, ester
Group, a cyano group, have a cyanato group or a glycidyl group, a silicone resin weight average particle diameter of 0.5 to 10 [mu] m 0.
A light-diffusing methacrylic resin composition containing 1 to 10 parts by weight.