JP5087403B2 - Silica composite polymer particles, method for producing the same, and use thereof - Google Patents

Description

  The present invention relates to silica composite polymer particles, a method for producing the same, and uses thereof. More specifically, the present invention relates to silica composite polymer particles in which a silica component is unevenly distributed on the surface and inside of the polymer component, a method for producing the same, and a use thereof.

Conventionally, in various molded articles such as lighting equipment covers, lenses, light guide plates, video disks, projection television screens, optical parts, cosmetic containers, vending machine front plates, signboards, product displays, tabletop containers, etc. Various resins are used as the material. Specifically, thermoplastic resins such as polycarbonate resin, polystyrene resin, and acrylic resin are used as various resins.
By the way, in various molded objects, in order to raise commercial value, such as the improvement of the designability, the improvement of light diffusivity is aimed at by mix | blending light-diffusion particle | grains with resin.

  In particular, for example, in the case of a lighting fixture cover or a liquid crystal display member, the larger the molded body is, the more difficult it is to obtain uniform diffusion. In addition, when the depth of the display device is sufficiently large, there is no problem. However, when the depth is reduced and the thickness is reduced, an image of a fluorescent lamp or a cold cathode tube as a light source may be visually observed. In this case, it is difficult to obtain a lighting fixture having a uniform light amount as a whole.

  Conventionally, as light diffusing particles, inorganic particles such as glass, calcium carbonate, and silica, or resin particles made of acrylic resin, styrene resin, or the like are used. However, in a molded body using these light diffusing particles, the light transmittance is lowered and it is difficult to say that the light diffusibility is improved.

  Various solutions have been made to solve such problems. Examples thereof are described in JP-A-10-265580 (Patent Document 1) and JP-A-2005-126683 (Patent Document 2). In these publications, light in which a composite polymer particle having a structure in which an inorganic substance is uniformly dispersed in a polymer or a structure in which a polymer surface is substantially uniformly covered with an inorganic substance or a silica film is blended with a transparent base resin is used. Diffusers have been proposed. The light diffusing plates of these publications can improve the light diffusibility as compared with the light diffusing plates containing particles made of only inorganic materials and particles made of only polymers.

In addition, light diffusing particles having various structures are used in fields where light diffuse reflectance is desired, such as paints and cosmetics.
For example, for addition to cosmetics, nylon fine particles, polymethyl methacrylate fine particles and the like are widely used because of their excellent extensibility.
However, since nylon fine particles adsorb components such as preservatives added to cosmetics, the antiseptic effect may change over time, which is not preferable.

In addition, since conventional polymethyl methacrylate fine particles have poor oil resistance and solvent resistance, there is a problem that aggregation occurs between particles in the presence of an oil component such as a humectant or alcohol.
In order to improve oil resistance and solvent resistance, crosslinked polymethyl methacrylate fine particles obtained by copolymerizing methyl methacrylate and a polyfunctional vinyl monomer have been reported. However, although these fine particles have improved oil resistance and solvent resistance, there is room for improvement in terms of the feeling of use and the natural finish due to the light diffusion effect of the particles.

Therefore, in order to improve the above problems, composite particles in which the surface of the polymer particles is covered with another polymer or an inorganic substance have been reported.
Among these, the composite particle in which the surface of the latter polymer particle is covered with an inorganic substance has an advantage that the refractive index at the interface between the polymer particle and the inorganic substance can be made larger than the refractive index at the interface between the polymers. is there. In addition, the former composite particles have an advantage that the touch feeling is better than the latter composite particles.

  For example, JP-A-5-170924 (Patent Document 3) reports composite particles in which the surface of polymer particles is covered with an inorganic substance. This publication describes composite particles in which a material that is smaller than a thermoplastic material and excellent in heat resistance is immobilized on the surface of the thermoplastic material. The method for producing composite particles described in this publication is a method in which a thermoplastic substance is heated to a softening point or higher and is obtained by mechanical shearing force by stirring a substance having excellent heat resistance and a thermoplastic substance. .

Moreover, in JP 2004-307837 A (Patent Document 4), polymer particles derived from a polymerizable vinyl monomer and polymer particles are exposed so as to expose the surface of the polymer particles with an opening ratio of 0.1-1. Composite particles comprising a silica coating to be coated have been reported.
Japanese Patent Laid-Open No. 10-265580 JP 2005-126683 A Japanese Patent Laid-Open No. 5-170924 JP 2004-307837 A

  However, the composite polymer particle described in the above publication has a structure in which the surface of the polymer particle is substantially uniformly covered with an inorganic substance or a silica film. Therefore, these particles have light diffusion reflectivity improved to some extent as compared with polymer particles alone. However, further improvement in diffuse reflectivity is desired.

  The inventor of the present invention has intensively studied to solve the above problems, and as a result, a polymerization step of a polymerizable vinyl monomer in the presence of an aqueous colloidal silica having a specific average particle diameter, and a condensation of a polyalkoxysiloxane oligomer. By producing silica composite polymer particles through the steps, silica composite polymer particles in which the silica component derived from the polyalkoxysiloxane oligomer is unevenly distributed inside and on the surface of the polymer component can be obtained. Surprisingly, it was found that the light has excellent diffuse reflectance, and the present invention has been achieved.

Thus, according to the present invention, a polymerizable vinyl monomer selected from styrene, acrylic acid, methacrylic acid, derivatives thereof and mixtures thereof in an aqueous suspension in which an aqueous colloidal silica having an average particle size of 90 nm or less is dispersed. After adding a mixture containing 100 parts by weight, 10 to 500 parts by weight of a polyalkoxysiloxane oligomer inert to the polymerizable vinyl monomer, and 0.01 to 10 parts by weight of a polymerization initiator, aqueous suspension polymerization is performed. To form a polymer component derived from the polymerizable vinyl monomer,
Next, an acid or base catalyst is added to the aqueous suspension after the aqueous suspension polymerization to form a silica component by condensation of the polyalkoxysiloxane oligomer, and silica composite polymer particles containing the polymer component and the silica component are obtained. There is provided a method for producing silica composite polymer particles.

Moreover, according to the present invention, there are silica composite polymer particles obtained by the above production method comprising a polymer component derived from a polymerizable vinyl monomer and a silica component,
The silica component is a condensate derived from a polyalkoxysiloxane oligomer that is inert to the polymerizable vinyl monomer, and
The silica component is obtained by firing the silica composite polymer particles to remove the polymer component, and the silica particles are in contact with a spherical or substantially spherical outer shell portion having a hollow structure and the outer shell portion, and There is provided silica composite polymer particles that are unevenly distributed in the silica composite polymer particles so as to have an inner shell portion that forms a convex portion toward the center.

Furthermore, according to this invention, the light-diffusion plate containing a transparent resin base material and the silica composite polymer particle obtained by the said manufacturing method is provided.
In addition, according to the present invention, at least a liquid crystal display panel having a display surface and a back surface, a light source disposed on the back surface side, and the light diffusion plate disposed between the liquid crystal display panel and the light source are provided. A liquid crystal display device characterized by the above is provided.

Since the silica composite polymer particle of the present invention has a unique shape in which the silica component constituting the particle is unevenly distributed in the particle, the silica composite polymer particle is excellent in light diffuse reflectance.
For example, when the above particles are used in a light diffusion plate, the light diffusibility can be improved as compared with the case where inorganic particles, resin particles such as acrylic particles and styrene resin are used in the same amount. Furthermore, since light diffusibility comparable to that obtained when inorganic particles or resin particles are used can be achieved with a relatively small amount of use, if the light diffusibility is comparable, the light transmittance expressed by the total light transmittance can be achieved. Reduction can be reduced.

Therefore, for example, when the particles of the present invention are used for a light diffusion plate of a liquid crystal display, it is possible to provide a uniform amount of light as a whole without observing an image of a fluorescent lamp or a cold cathode tube as a light source. This uniform amount of light can be provided even when the liquid crystal display is thin and large.
In addition, for example, blending into cosmetics not only suppresses reflection of light in the regular reflection direction, but also diffuses light in a wider direction, so a soft focus effect that can not be obtained with particles of the conventional shape is expected it can.

It is a schematic sectional drawing of the silica particle after baking of the silica composite polymer particle of this invention. It is the schematic of the silica composite polymer particle of this invention. It is the schematic of the light diffusing plate of this invention. It is a schematic sectional drawing of a liquid crystal display device. 2 is an electron micrograph of silica particles after firing the silica composite polymer particles of Example 1. FIG. 3 is a graph of the reflected light intensity distribution of Example 1. 4 is an electron micrograph of silica particles after firing the silica composite polymer particles of Example 2. FIG. 6 is a graph of the reflected light intensity distribution of Example 2.

4 is an electron micrograph of silica particles after firing the silica composite polymer particles of Example 3. FIG. 7 is an electron micrograph of silica particles after firing the silica composite polymer particles of Example 7. FIG. 4 is an electron micrograph of silica particles after firing the silica composite polymer particles of Example 11. FIG. It is an electron micrograph of the silica particle after baking the silica composite polymer particle of Example 12. It is an electron micrograph of the silica particle after baking the silica composite polymer particle of Example 13. It is an electron micrograph of the silica particle after baking the silica composite polymer particle of Example 14. It is an electron micrograph of the silica particle after baking the silica composite polymer particle of Example 15. 4 is an electron micrograph of silica particles after firing a silica composite polymer particle of Comparative Example 2. FIG. It is a graph of the reflected light intensity distribution of the comparative example 4. It is a graph of the reflected light intensity distribution of the comparative example 6.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polymer component 2 Silica component 3 Silica composite polymer particle 4 Light diffusing plate 5 Transparent base resin 6 Light diffusing particle 9 Light source 10 Liquid crystal display panel 11, 12 Substrate 13 Liquid crystal layer 14, 15 Electrode 16, 17 Alignment film 18 Reflection Sheet

Hereinafter, the present invention will be described in more detail.
The silica composite polymer particles of the present invention are spherical or substantially spherical, and the silica component is unevenly distributed on a part of the surface thereof. The uneven distribution can be confirmed by the shape of the silica particles derived from the silica component obtained by firing the silica composite polymer particles and removing the polymer component. As shown in the schematic cross-sectional view of FIG. 1, the silica component includes a spherical or substantially spherical outer shell portion having a hollow structure, and an inner shell portion that is in contact with the outer shell portion and forms a convex portion toward the center. It is considered that the silica composite polymer particles are unevenly distributed in a state corresponding to the silica particles. For example, the silica composite polymer particle of the present invention is considered to have a structure in which the silica component 2 is unevenly distributed on the surface and inside of the spherical or substantially spherical polymer component 1 as shown in the schematic diagram of FIG. It is done. In the figure, reference numeral 3 means silica composite polymer particles. The shape and size of the convex portion can be appropriately adjusted by changing the type and amount of the raw material.

  By having such a structure, complex reflection and refraction of light occurs as compared with spherical silica or coated polymer particles whose surface is coated with silica or the like. As a result, it is possible to obtain silica composite polymer particles capable of expressing strong light diffuse reflectance.

  In the silica composite polymer particles of the present invention, it is preferable that the silica component is unevenly distributed in the silica composite polymer particles so that the opening ratio of the outer shell portion of the silica particles after firing is 0.5 to 1. The opening ratio of the silica particles is strictly the same as the opening ratio of the silica component corresponding to the outer shell part due to shrinkage of the silica component during firing or lack of a thin area at the end of the silica component. Although it may differ, the inventor has confirmed that the opening ratio of the silica component of the silica composite polymer particles and the opening ratio of the outer shell portion of the silica particles are substantially the same. The opening ratio is a value calculated by dividing the area of the opening by the projected area of the silica particles. A more preferable aperture ratio is 0.5 to 0.8.

  Furthermore, it is preferable that the height h of the outer shell portion of the silica particles after firing and the diameter D of the silica particles have a relationship of 0.5 ≦ h / D <1. However, in this specification, h / D is a silica particle shown in the schematic cross-sectional view of FIG. 1 by burning the silica composite polymer particles to burn out the polymer component. I use it. The h / D of the silica particles is strictly different from the h / D of the silica composite polymer particles due to shrinkage of the silica component during firing or lack of a thin region at the end of the silica component. In some cases, the inventor has confirmed that the h / D of the silica component corresponding to the outer shell portion and the h / D of the silica particles are substantially the same. More preferable h / D is 0.5 to 0.9.

Hereinafter, the silica composite polymer particles of the present invention will be described with reference to the production method thereof.
First, a mixture containing a polymerizable vinyl monomer, a polyalkoxysiloxane oligomer, and a polymerization initiator is added to an aqueous suspension containing colloidal silica, and the polymerizable vinyl monomer is subjected to aqueous suspension polymerization. A polymer component is obtained.

The polymerizable vinyl monomer that can be used in the present invention is not particularly limited. For example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexyl Styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, 3,4-di Styrene and its derivatives such as chlorostyrene,
Vinyl esters such as vinyl acetate, vinyl propionate and vinyl butyrate,

Methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, 2-acrylate Chlorethyl, phenyl acrylate, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate , Stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethyl methacrylate α- methylene aliphatic monocarboxylic acid esters such as aminoethyl,

There are acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and the like. Acrylic acid, methacrylic acid, maleic acid, fumaric acid and the like can also be used. Further, two or more of these may be used in combination. Moreover, the hydrogen atom in these monomers may be substituted with a halogen atom such as a fluorine atom. Examples of the substituted monomer include trifluoroethyl methacrylate.

Further, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone, N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl compounds such as N-vinylpyrrolidone, vinyl naphthalene salts, and the like can be used alone or in combination of two or more in a range not impeding the effects of the present invention.
Among the polymerizable vinyl monomers, styrene, methyl methacrylate, etc., which are inexpensive in terms of cost, are preferable.

The polymer component may be crosslinked with a monomer having two or more functional groups such as ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, divinylbenzene and the like.
In the present invention, the polyalkoxysiloxane oligomer, which is a precursor of the silica component, is inert to the polymerizable vinyl monomer (meaning that it is not copolymerized), and preferably has a structural formula as shown below.

In the formula, R may be the same or different.
Among the above structural formulas, for example, oligomers such as polymethoxysiloxane, polyethoxysiloxane, polypropoxysiloxane, polybutoxysiloxane, and the like can be given. Among these, polymethoxysiloxane oligomers and polybutoxysiloxane oligomers that are poorly water-soluble and have good phase separation from the resin are preferable. Particularly preferred are polymethoxysiloxane oligomers and polybutoxysiloxane oligomers having a weight average molecular weight of 300 to 3000, more preferably 300 to 2000. When the weight average molecular weight is less than 300 or more than 3000, both are not preferable because it is difficult to form the silica composite polymer particles of the present invention.

In addition, a weight average molecular weight is measured on condition of the following using GPC.
Column: “TSK GEL” (manufactured by Tosoh Corporation)
G-1000H,
G-2000H
G-4000H
Effluent: Tetrahydrofuran Outflow rate: 1 ml / min Outflow temperature: 40 ° C
In low molecular weight alkoxysiloxanes such as tetramethoxysilane and tetraethoxysilane where n = 1-2 in the above molecular formula, the water solubility becomes stronger due to hydrolysis of the functional group, so it should be stably present in the monomer droplets. Is difficult and undesirable. In addition, a polyalkoxysiloxane oligomer in which n = 40 or more in the above molecular formula is not preferable because compatibility and condensability with the polymerizable vinyl monomer may be lowered. As for n, 3-20 are more preferable.

The addition amount of the polyalkoxysiloxane oligomer is preferably 10 to 500 parts by weight, more preferably 20 to 300 parts by weight with respect to 100 parts by weight of the polymerizable vinyl monomer. When the amount is less than 10 parts by weight or more than 500 parts by weight, it is difficult to obtain a composite state of the present invention, which is not preferable.
In addition, hydrolysable alkoxy metal compounds other than silicon-based compounds can be added to these polyalkoxysiloxane oligomers for the purpose of adding functions such as ultraviolet absorption.

A polymerization initiator is used for the polymerization of the polymerizable vinyl monomer. Examples of the polymerization initiator include oil-soluble peroxide polymerization initiators and azo polymerization initiators that are usually used in aqueous suspension polymerization. Specific examples include benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, orthochlorobenzoyl peroxide, orthomethoxybenzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxydicarbonate, cumene hydroperoxide, cyclohexanone peroxide, t-butyl. Peroxide polymerization initiators such as hydroperoxide, diisopropylbenzene hydroperoxide,
2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2,3-dimethylbutyronitrile), 2,2′- Azobis (2-methylbutyronitrile), 2,2′-azobis (2,3,3-trimethylbutyronitrile), 2,2′-azobis (2-isopropylbutyronitrile), 1,1′-azobis (Cyclohexane-1-carbonitrile), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile, (2-carbamoylazo) isobutyronitrile, 4,4′-azobis (4-cyanovaleric acid) ), And azo initiators such as dimethyl-2,2′-azobisisobutyrate.

Among these, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), benzoyl peroxide, lauroyl peroxide, and the like are in terms of the decomposition rate of the polymerization initiator. Is preferable.
The polymerization initiator is preferably used in an amount of 0.01 to 10 parts by weight, more preferably 0.1 to 5.0 parts by weight with respect to 100 parts by weight of the polymerizable vinyl monomer. When the polymerization initiator is less than 0.01 parts by weight, it is difficult to achieve the function of initiating the polymerization, and when it exceeds 10 parts by weight, it is not preferable because it is not economical.

In order to color the silica component, metal oxide pigments such as titanium oxide, zinc oxide, magnesium oxide, chromium oxide, and zirconium oxide may be used.
The polymerizable vinyl monomer, the polyalkoxysiloxane oligomer, the polymerization initiator, and other components are uniformly mixed by a known method to form a mixture.

Next, examples of the aqueous medium for aqueous suspension polymerization of the mixture include water or a mixed medium of water and a water-soluble solvent such as alcohol (for example, methanol, ethanol). The amount of the aqueous medium used is usually 100 to 1000 parts by weight with respect to a total of 100 parts by weight of the polymerizable vinyl monomer and polyalkoxysiloxane oligomer in order to stabilize the suspension polymerized particles.
In order to suppress the generation of emulsified particles in an aqueous system, water-soluble polymerization inhibitors such as nitrites, sulfites, hydroquinones, ascorbic acids, water-soluble vitamin Bs, citric acid, and polyphenols may be used. Good.

In the present invention, silica composite polymer particles having a structure in which a silica component is unevenly distributed on the surface and inside of a spherical or substantially spherical polymer component are obtained by using aqueous colloidal silica having a specific average particle size.
As the aqueous colloidal silica, those having an average particle diameter of 90 nm or less are used. When it is larger than 90 nm, it is difficult to obtain silica composite polymer particles having a structure in which the silica component is unevenly distributed on the surface and inside of the polymer component. Furthermore, the average particle diameter is preferably as small as possible, and the more preferable average particle diameter is 0.1 to 70 nm.

Here, the average particle diameter of the aqueous colloidal silica is a specific surface area diameter obtained by measurement by a nitrogen adsorption method (BET method). The average particle diameter (specific surface area diameter) (Dnm) is given by the formula D = 2720 / S from the specific surface area Sm ² / g as measured by the nitrogen adsorption method.

As the aqueous colloidal silica, aqueous colloidal silica derived from precipitated silica powder, vapor phase silica powder, etc., or aqueous colloidal silica in which silica powder is stably dispersed to the primary particle level in water can be used. Of these, the latter is preferred. Aqueous colloidal silica can improve the dispersion stability of colloidal silica since an aqueous medium is used for the production of silica composite polymer particles. Aqueous colloidal silica is generally commercially available, and it is preferable to use a dispersion in water of 5 to 50% by weight which can be easily obtained.
The aqueous colloidal silica is preferably contained in the aqueous suspension at a concentration of 0.5 to 20% by weight.

  By the way, sol-like organosilica in which colloidal silica is dispersed in an organic solvent is also known as colloidal silica. The inventors of the present invention have confirmed that organocomposite particles having a specific shape of the present invention cannot be obtained with organosilica. This means that in order to obtain the silica composite polymer particles of the present invention, any kind of colloidal silica can be used, and selection of the kind is important.

  Furthermore, you may add a suspension stabilizer as needed. For example, phosphates such as calcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, pyrophosphates such as calcium pyrophosphate, magnesium pyrophosphate, aluminum pyrophosphate, zinc pyrophosphate, calcium carbonate, magnesium carbonate, calcium hydroxide And dispersion stabilizers of poorly water-soluble inorganic compounds such as magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, and barium sulfate. Of these, tricalcium phosphate, magnesium pyrophosphate and calcium pyrophosphate produced by the metathesis method are preferable because the polymer component can be stably obtained.

The suspension stabilizer can be used in combination with a surfactant such as an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant.
Examples of the anionic surfactant include fatty acid oils such as sodium oleate and castor oil potassium, alkyl sulfate salts such as sodium lauryl sulfate and ammonium lauryl sulfate, alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate, and alkylnaphthalene sulfone. Acid salts, alkane sulfonates, dialkyl sulfosuccinates, alkyl phosphate esters, naphthalene sulfonate formalin condensates, polyoxyethylene alkyl phenyl ether sulfates, polyoxyethylene alkyl sulfates and the like.

  Nonionic surfactants include, for example, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxysorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin fatty acid ester, oxy Examples include ethylene-oxypropylene block polymers.

Examples of the cationic surfactant include alkylamine salts such as laurylamine acetate and stearylamine acetate, and quaternary ammonium salts such as lauryltrimethylammonium chloride.
Examples of the zwitterionic surfactant include lauryl dimethylamine oxide and phosphate ester or phosphite ester surfactants.

  These suspension stabilizers and surfactants may be used alone or in combination of two or more. However, in consideration of the diameter of the obtained polymer component and the dispersion stability at the time of polymerization, the suspension stabilizer It is used by appropriately adjusting the selection and usage. Usually, the addition amount of the suspension stabilizer is 0.5 to 15 parts by weight with respect to 100 parts by weight of the polymerizable vinyl monomer, and the addition amount of the surfactant is 0.00 with respect to 100 parts by weight of the aqueous medium. 001 to 0.1 parts by weight.

An aqueous suspension polymerization is performed by adding the mixture to the aqueous medium thus prepared.
As a dispersion method of the mixture, for example, a method in which the mixture is directly added to the aqueous medium and dispersed in the aqueous medium as monomer droplets by stirring force of a propeller blade or the like, a disperser using a high shear force composed of a rotor and a stator And a method of dispersing using a homomixer or an ultrasonic disperser. Among these, the mixture is pressed into an aqueous medium through a high-pressure disperser using a collision between monomer droplets such as a microfluidizer or a nanomizer or a collision force against the wall of the machine, or through an MPG (microporous glass) porous film. Dispersion by a method is preferable because the particle diameter can be made more uniform.

The aqueous suspension in which the mixture is dispersed as spherical monomer droplets is then heated to initiate suspension polymerization. During the polymerization reaction, it is preferable to stir the aqueous suspension, and the stirring may be performed so gently as to prevent the monomer droplets from floating and the particles from being settled after the polymerization.
In the suspension polymerization, the polymerization temperature is preferably about 30 to 100 ° C, more preferably about 40 to 80 ° C. The time for maintaining this polymerization temperature is preferably about 0.1 to 20 hours.

  In addition, when the boiling point of the polymerizable vinyl monomer and the polyalkoxysiloxane oligomer is near the polymerization temperature or higher than the polymerization temperature, the pressure resistant polymerization equipment such as an autoclave is prevented so that the polymerizable vinyl monomer and the polyalkoxysiloxane oligomer do not volatilize. It is preferable to polymerize under sealing or under pressure.

  Next, the silica component is formed by condensing the polyalkoxysiloxane oligomer, and the silica composite polymer particle of the present invention including the polymer component and the silica component can be obtained. Examples of the condensation method of the polyalkoxysiloxane oligomer include dehydration condensation using an acid catalyst or a base catalyst. As the acid catalyst and the base catalyst, hydrochloric acid, sulfuric acid, nitric acid, ammonia, sodium hydroxide, potassium hydroxide, ammonium nitrate, sodium pyrophosphate and the like can be used. When the production container is made of steel or stainless steel, basic sodium hydroxide, ammonia, sodium pyrophosphate and the like are preferable from the viewpoint of corrosion and the like. The addition amount of the catalyst is preferably 0.01 to 30 parts by weight with respect to 100 parts by weight of the polyalkoxysiloxane oligomer. More preferably, it is 1 to 15 parts by weight.

After the condensation, the silica composite polymer particles are separated as a water-containing cake by a method such as suction filtration, centrifugal dehydration, centrifugal separation, pressure dehydration, and the obtained water-containing cake is washed with water and dried to obtain the desired silica composite weight. Combined particles can be obtained.
The size and shape of the silica composite polymer particles of the present invention are not particularly limited. According to the method for producing silica composite polymer particles, particles having an average particle diameter of 1 to 100 μm can be obtained.

Here, the adjustment of the average particle diameter of the particles can be performed by adjusting the mixing conditions of the mixture and water, the addition amount of other suspension stabilizers and surfactants, the stirring conditions of the agitator, and the dispersion conditions. is there.
The silica composite polymer particles of the present invention preferably contain 10 to 500 parts by weight of silica component, more preferably 20 to 300 parts by weight, per 100 parts by weight of polymer component.

  The silica composite polymer particles of the present invention preferably have a luminous intensity of 70 or more when the peak luminous intensity in the regular reflection direction is 100 at a reflection angle of 0 ° with respect to incident light of −45 ° by a three-dimensional photometer. This luminous intensity indicates that the silica composite polymer particles of the present invention are excellent in light diffusibility and not only suppress regular reflection light but also diffuse light in a wider direction. When the luminous intensity is 70 or more, when the silica composite polymer particles are used for the light diffusion plate, an effect that the light from the incident light source can be uniformly diffused can be expected. On the other hand, when used in cosmetics such as foundations, a soft focus effect that cannot be obtained with particles having a conventional shape can be expected. When it is smaller than 70, the reflection of light in the regular reflection direction is strong and the diffusion is insufficient, and a sufficient soft focus effect cannot be expected when blended into cosmetics. A more preferable luminous intensity is 75-100.

The silica composite polymer particles of the present invention can be suitably used for applications where light diffusion is desired. Examples of such applications include light diffusion plates, cosmetics, paints, and the like.
As illustrated in FIG. 3, the light diffusing plate 4 includes a transparent base resin 5 and silica composite polymer particles (light diffusing particles) 6 blended in the resin 5. The light diffusing particles mean particles that can improve light diffusibility as compared with an unblended resin by blending with a transparent base resin.

The transparent base resin and the silica composite polymer particles are preferably made of a material having a refractive index difference of 0.01 to 0.15 between the transparent base resin and the polymer particles in the silica composite polymer particles. . When the difference in refractive index is less than 0.01, it is not preferable because excellent light diffusibility is hardly obtained. If it is larger than 0.15, it is difficult to obtain a light diffusing plate having a good balance between light diffusibility and light transmittance, which is not preferable. A more preferable refractive index difference is 0.015 to 0.145.
Silica composite polymer particles have the above structure, which results in more complex light reflection and refraction than coated polymer particles with the surface of inorganic particles or polymer particles coated with silica. The inventor has found that sex can be expressed.

  In the light diffusing plate of the present invention, the mixing ratio of the silica composite polymer particles is preferably 0.1 to 20 parts by weight with respect to 100 parts by weight of the transparent base resin. If particles having such a range and the silica component unevenly distributed in a specific shape as described above are used, it is possible to obtain a light diffusing plate that is more excellent in light diffusibility and less deteriorated in light transmittance. In addition, a more preferable mixing ratio is 0.3 to 15 parts by weight, and a more preferable mixing ratio is 0.5 to 10 parts by weight.

Moreover, it is preferable that the silica component in a silica composite polymer particle is contained in the light-diffusion board in 0.01-15 weight part with respect to 100 weight part of light-diffusion boards. When the silica component is contained in this range and the silica component is unevenly distributed in the particles as described above, both light diffusibility and light transmittance can be achieved at a high level. A more preferable content of the silica component is 0.1 to 5 parts by weight. In addition, content of the silica component here means the value estimated from the usage-amount of the raw material polyalkoxysiloxane oligomer.
The light diffusing plate usually includes a light emitting surface, an opposite surface facing the light emitting surface, and a side surface defined by the light emitting surface and the opposite surface. A light source for causing light to enter the light diffusing plate is disposed on the back surface of a lighting fixture, a liquid crystal display, or the like, for example.

Note that the wavelength of light diffused in the light diffusion plate may be any of the visible light region, the infrared region, and the ultraviolet region. It is preferable to include at least a visible light region.
The shape of the light diffusing plate is not particularly limited, and can be appropriately determined according to the intended use. For example, examples of the shape of the light emitting surface include a rectangle, a square, a polygon, a circle, and an ellipse. Specifically, the length of the side surface perpendicular to the light emitting surface is preferably 1: 1500 to 1: 4 with respect to the maximum length of the light emitting surface. More specifically, the length of the side surface is preferably 1 to 5 mm, and the maximum length of the light emitting surface is preferably 2 to 150 cm.

  The light diffusion plate of the present invention is usually obtained by molding a kneaded product obtained by melt-kneading silica composite polymer particles and a transparent base resin into a desired shape by extrusion molding, injection molding or the like. Can do. Here, since the silica composite polymer particles have good dispersibility with respect to the transparent base resin, they can be mixed uniformly without particularly setting the kneading conditions severely.

Next, constituent materials of the light diffusing plate will be described.
First, a thermoplastic resin can usually be used for the transparent base resin constituting the light diffusion plate. In the present specification, the term “transparent” includes translucent. Further, the term “transparent” means that it is transparent to light having a desired wavelength, and is not necessarily transparent to light having all wavelengths.

  Examples of the thermoplastic resin include (meth) acrylic resin, (meth) alkyl acrylate-styrene copolymer resin, polycarbonate resin, polyester resin, polyethylene resin, polypropylene resin, polystyrene resin, and the like. The above resins may be used alone or in combination of two or more. (Meth) acryl means methacryl or acrylic.

Among these, (meth) acrylic resin, (meth) acrylic acid acrylic-styrene copolymer resin, polycarbonate resin, polyester resin, and polystyrene resin are preferable because they have excellent transparency.
The size and shape of the silica composite polymer particles used for the light diffusion plate are not particularly limited. For example, silica composite polymer particles having an average particle diameter of 1 to 100 μm can be used.

The light diffusing plate of the present invention has a total light transmittance of 55% or more, and is measured by an automatic goniophotometer, and a peak value obtained by changing the angle from the optical axis relative to the peak value on the incident optical axis of light. The angle at which 50% of the above can be obtained can be 40 degrees or more. This angle indicates that the light diffusion plate of the present invention is excellent in light diffusibility. In the case of 40 degrees or more, even if it is used in a device that has been enlarged recently such as a liquid crystal display, an image of a fluorescent lamp or a cold cathode tube as a light source is not visually observed, and a uniform light amount can be provided as a whole.
In the case of 40 degrees or less, the light diffusibility is insufficient, and an image of a fluorescent lamp, a cold cathode tube, or the like as a light source can be visually observed.

  Furthermore, the present invention provides a liquid crystal display device provided with the light diffusing plate. The configuration of the liquid crystal display device is not particularly limited as long as it includes the light diffusion plate. For example, as shown in FIG. 4, the liquid crystal display device is disposed between a liquid crystal display panel 10 having a display surface and a back surface, a light source 9 disposed on the back surface side of the panel, and the liquid crystal display panel and the light source. And at least a light diffusing plate 4. This arrangement of light sources is referred to as a direct backlight arrangement.

The liquid crystal display panel has a configuration in which a liquid crystal layer 13 is sandwiched between a pair of substrates (11, 12). On the liquid crystal layer side of the substrate, electrodes (14, 15) and alignment films (16, 17) covering the electrodes are provided. Here, the electrode may include a thin film transistor. Further, the liquid crystal display panel may include a polarizing sheet, an antireflection sheet 18 and the like.
A prism sheet or the like may be disposed on the light emitting surface of the light diffusion plate on the liquid crystal panel side. Further, a reflective sheet may be disposed on the back surface of the light source.

Furthermore, you may use the silica composite polymer particle of this invention as a raw material of cosmetics or a coating material.
When used in cosmetics, the average particle size is preferably about 3 to 50 μm from the viewpoint of the feeling of use. When it exceeds 50 μm, the usability may be deteriorated. Particularly preferably, it is about 3 to 20 μm which makes the feel smoother.

Specific cosmetics to be blended with the silica composite polymer particles of the present invention include solid cosmetics such as funny and foundation, powdery cosmetics such as baby powder and body powder, lotion, milky lotion, cream and body lotion. And liquid cosmetics.
The blending ratio in these cosmetics varies depending on the type of cosmetic, but it is preferably 1 to 20% by weight and particularly preferably 3 to 15% by weight in the case of solid cosmetics such as funny and foundation. Moreover, in the case of powdery cosmetics such as baby powder and body powder, the content is preferably 1 to 20% by weight, particularly preferably 3 to 15% by weight. Furthermore, in the case of liquid cosmetics such as lotion, milky lotion, cream, liquid foundation, body lotion, pre-shave lotion, the content is preferably 1 to 15% by weight, more preferably 3 to 10% by weight.

  In addition, these cosmetics include inorganic compounds such as mica and talc, pigments for coloring such as iron oxide, titanium oxide, ultramarine blue, bitumen, and carbon black, or azo for improving optical function and touch. Synthetic dyes and the like such as those can be added. In the case of liquid cosmetics, the liquid medium is not particularly limited, but water, alcohol, hydrocarbons, silicone oil, vegetable or animal oils and the like can also be used. To these cosmetics, in addition to the above-mentioned other ingredients, moisturizers, anti-inflammatory agents, whitening agents, UV care agents, bactericides, antiperspirants, refreshing agents, fragrances and the like commonly used in cosmetics are added. Thus, various functions can be added.

  In particular, the silica composite polymer particles can be suitably used as a raw material for liquid cosmetics. In liquid cosmetics, moisturizers, oils, surfactants, UV absorbers, drugs, colorants, salts, polymer compounds, perfume ingredients, stabilizers that are commonly used in cosmetics as long as the quality is not impaired. A buffering agent etc. can be mix | blended.

  Examples of the moisturizing material used in the present invention include polyethylene glycol, propylene glycol, glycerin, 1,3-butylene glycol, xylitol, sorbitol, maltitol, chondroitin sulfate, hyaluronic acid, mucoitin sulfate, caronic acid, atelocollagen, cholesteryl-12. Examples include hydroxystearate, sodium lactate, bile salt, d, l-pyrrolidone carboxylate, short-chain soluble collagen, diglycerin (EO) PO adduct, Izayoi rose extract, yarrow extract, and merirot extract. However, it is not limited to these.

  Oils used in liquid cosmetics include liquid oils such as avocado oil, camellia oil, turtle oil, macadamia nut oil, corn oil, mink oil, olive oil, rapeseed oil, egg yolk oil, sesame oil, persic oil, wheat germ oil, southern oil Oil, castor oil, linseed oil, safflower oil, cottonseed oil, eno oil, soybean oil, peanut oil, teaseed oil, kaya oil, rice bran oil, cinnagar oil, Japanese kiri oil, jojoba oil, germ oil, triglycerin, trioctane Examples include glycerin acid and glycerin triisopalmitate. As solid fats and oils, cacao butter, palm oil, horse fat, hardened palm oil, palm oil, beef tallow, sheep fat, hardened beef tallow, palm kernel oil, pork fat, beef bone fat, owl kernel oil, hardened oil, cow leg fat, Owl, hydrogenated castor oil and the like can be mentioned. As waxes, beeswax, candelilla wax, cotton wax, carnauba wax, bayberry wax, ipotarou, whale wax, montan wax, nukarou, lanolin, kapok wax, lanolin acetate, liquid lanolin, sugarcane wax, lanolin fatty acid isopropyl, lauric acid hexyl, reduced lanolin, jojopalo C, hard lanolin, shellac wax, POE lanolin alcohol ether, POE lanolin alcohol acetate, POE cholesterol ether, lanolin fatty acid polyethylene glycol, POE hydrogenated lanolin alcohol ether, and the like. Examples of the hydrocarbon oil include liquid paraffin, ozokerite, squalene, pristane, paraffin, ceresin, petrolatum, microcrystalline wax, and the like, but the oil content is not limited thereto.

  Examples of surfactants used in liquid cosmetics include sorbitan monooleate, sorbitan monoisostearate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan sesquioleate, sorbitan trioleate, penter Sorbitan fatty acid esters such as 2-ethylhexyl diglycerol sorbitan, tetra-2-ethylhexyl diglycerol sorbitan, mono-cotton oil fatty acid glycerin, monoerucic acid glycerin, sesquioleate glycerin, monostearate glycerin, α, α '-Glycerin polyglycerol fatty acids such as glycerin pyroglutamate oleate, glyceryl monostearate malate, propylene glycol such as propylene glycol monostearate Fatty acid esters, hydrogenated castor oil derivatives, glycerin alkyl ether, POE-sorbitan monooleate, POE-sorbitan monostearate, POE-sorbitan tetraoleate and other sorbitan fatty acid esters, POE-sorbite monolaurate, POE- POE sorbite fatty acid esters such as sorbite monooleate, POE-sorbite pentaoleate, POE-sorbite monostearate, POE-glycerol monostearate, POE-glycerol monoisostearate, POE-glycerol triisostearate, etc. POE glycerin fatty acid esters, POE monooleate, POE distearate, POE monodiolate, POE fatty acid esters such as ethylene glycol stearate, POE POE alkyl ethers such as uryl ether, POE oleyl ether, POE stearyl ether, POE behenyl ether, POE2-octyldodecyl ether, POE cholestanol ether, POE octyl phenyl ether, POE nonyl phenyl ether, POE dinonyl phenyl ether, etc. POE alkylphenyl ethers, pluronic types such as pluronic, POE / POP cetyl ether, POE / POP2-decyltetradecyl ether, POE / POP monobutyl ether, POE / POP hydrogenated lanolin, POE / POP glycerin ether, etc. POP alkyl ethers, tetra-POE / tetra-POP ethylenediamine condensates such as Tetronic, POE castor oil, POE hydrogenated castor oil, P E-hardened castor oil monoisostearate, POE-hardened castor oil triisostearate, POE hardened castor oil monopyroglutamic acid monoisostearic acid diester, POE hardened castor oil maleic acid and other POE castor oil-hardened castor oil derivatives, POE sorbite beeswax, etc. POE beeswax lanolin derivatives, coconut oil fatty acid diethanolamide, lauric acid monoethanolamide, alkanolamides such as fatty acid isopropanolamide, POE propylene glycol fatty acid ester, POE alkylamine, POE fatty acid amide, sucrose fatty acid ester, POE nonylphenylformaldehyde Examples include condensates, alkylethoxydimethylamine oxide, trioleyl phosphate, and the like, but are not limited thereto (POE is polyoxyethylene). Len and POP are polyoxypropylene).

  Examples of ultraviolet absorbers used in liquid cosmetics include paraaminobenzoic acid (hereinafter abbreviated as PABA), PABA monoglycerin ester, N, N-dipropoxy PABA ethyl ester, N, N-diethoxy PABA ethyl ester, N, N -Benzoic acid-based UV absorbers such as dimethyl PABA ethyl ester, N, N-dimethyl PABA butyl ester, anthranilic acid-based UV absorbers such as homomenthyl-N-acetylanthranylate, amyl salicylate, menthyl salicylate, homomenthyl salicylate, Salicylic acid UV absorbers such as octyl salicylate, phenyl salicylate, benzyl salicylate, p-isopropanol phenyl salicylate, octyl cinnamate, ethyl-4-isopropyl cinnamate, ethyl-2 5-diisopropylcinnamate, ethyl-2,4-diisopropylcinnamate, methyl-2,4-diisopropylcinnamate, propyl-p-methoxycinnamate, isopropyl-p-methoxycinnamate, isoamyl-p-methoxycinnamate, Octyl-p-methoxycinnamate (2-ethylhexyl-p-methoxycinnamate), 2-ethoxyethyl-p-methoxycinnamate, cyclohexyl-p-methoxycinnamate, ethyl-α-cyano-β- Phenyl cinnamate, 2-ethylhexyl-α-cyano-β-phenyl cinnamate, glyceryl mono-2-ethylhexanoyl-diparamethoxy cinnamate, 3,4,5-trimethoxycinnamate 3-methyl- 4- [Methylbis (trimethylsiloxy) silyl] bu Cinnamic acid-based UV absorbers such as 2,4'-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2 ', 4 , 4′-tetrahydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-4′-methylbenzophenone, 2-hydroxy-4methoxybenzophenone-5-sulfonate, 4-phenylbenzophenone, Benzophenone ultraviolet absorbers such as 2-ethylhexyl-4′-phenyl-benzophenone-2-carboxylate, hydroxy-4-n-octoxybenzophenone, 4-hydroxy-3-carboxybenzophenone, 3- (4′- Methylbenzylidene) -d, l-camph -, 3-benzylidene-d, l-camphor, urocanic acid, urocanic acid ethyl ester, 2-phenyl-5-methylbenzoxazole, 2,2'-hydroxy-5-methylphenylbenzotriazole, 2- (2 ' -Hydroxy-5'-t-octylphenyl) benzotriazole, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, dibenzalazine, dianisoylmethane, 4-methoxy-4'-t-butyldibenzoylmethane , 5- (3,3-dimethyl-2-norbornylidene) -3-pentan-2-one and the like, but is not limited thereto.

  Drugs used in liquid cosmetics include nonyl acid valenylamide, nicotinic acid benzyl ester, nicotinic acid β-butoxyethyl ester, capsaicin, gingerone, cantalis tincture, ictamol, caffeine, tannic acid, α-borneol, nicotinic acid tocopherol , Inositol hexanicotinate, cyclandrate, cinnarizine, trazoline, acetylcholine, verapamil, cephalanthin, γ-oryzanol, clotrimazole, pentachlorophenol, trichlorophenolcaproate, tribromophenolcaproate, lauryltriphenylphosphonium pro Amide, diantazole hydrochloride, paraacetylaminophenyl rhodan, methylosal, undecylenic acid, zinc undecylenate, dermaside, valithione Prolone nitrone, siccanin, miconazole, econazole, isoconazole, sulconazole, thioconazole, bifonazole, oxyconazole, ketoconazole, cyclopirox olamine, tolcyclate, naphthifine, griseofulvin, 5-fluorocytosine, etc. It is not something.

  Colorants used in liquid cosmetics include inorganic white pigments such as titanium dioxide and zinc oxide, inorganic red pigments such as iron oxide (Bengara) iron titanate, inorganic brown pigments such as γ-iron oxide, and yellow iron oxide , Inorganic yellow pigments such as ocher, inorganic black pigments such as black iron oxide, carbon black, low-order titanium oxide, inorganic purple pigments such as mango violet and cobalt violet, chromium oxide, chromium hydroxide, cobalt titanate, etc. Green pigments, blue pigments such as ultramarine and bitumen, titanium oxide coated mica, titanium oxide coated bismuth oxychloride, titanium oxide coated talc, colored titanium oxide coated mica, bismuth oxychloride, pearl pigments such as fish scale foil, aluminum powder , Metal powder pigments such as copper powder, red 201, red 202, red 204, red Organic pigments such as 05, Red 220, Red 226, Red 228, Red 405, Orange 203, Orange 204, Yellow 205, Yellow 401 and Blue 404, Red 3 and Red 104 Red 106, red 227, red 230, red 401, red 505, orange 205, yellow 4, yellow 5, yellow 202, yellow 203, green 3 and blue 1 Examples include organic pigments such as zirconium, barium, and aluminum lakes, and natural pigments such as chlorophyll and β-caroline, but are not limited thereto.

Examples of the salt used in the liquid cosmetic include natural salts such as rock salt, sea salt, and mineral spring lake salt.
Examples of the polymer compound used in the liquid cosmetic include gum arabic, gum tragacanth, galactan, guar gum, carop gum, caraya gum, carrageenan, pectin, agar, quince seed (malmello), alge colloid (gypsum extract), starch (rice, corn) , Potato, wheat), plant polymers such as glycyrrhizic acid, microbial polymers such as xanthan gum, dextran, succinoglucan, pullulan, animal polymers such as collagen, casein, alpmin, gelatin, carboxymethyl starch, methyl Starch polymers such as hydroxypropyl starch, methylcellulose, nitrocellulose, ethylcellulose, methylhydroxypropylcellulose, hydroxyethylcellulose, cellulose sulfate sodium , Hydroxypropylcellulose, sodium carboxymethylcellulose (CMC), crystalline cellulose, cellulose polymers such as cellulose powder, alginic acid polymers such as sodium alginate and propylene glycol alginate, polyvinyl alcohol, polyvinyl methyl ether, polyvinylpyrrolidone, carboxy Vinyl polymers such as vinyl polymers (Carbopol), polyoxyethylene polymers such as polyethylene glycol 2000, 4000 and 6000, polyoxyethylene polyoxypropylene copolymer copolymers, sodium polyacrylate, poly Examples include, but are not limited to, acrylic polymers such as ethyl acrylate and polyacrylamide, polyethyleneimine, and cationic polymers. .

As a fragrance ingredient used in liquid cosmetics, animal-based, plant-based, mineral-based natural fragrances and synthetic fragrances can be used.
Examples of stabilizers used in liquid cosmetics include 1-hydroxyethane-1,1-diphosphonic acid, 1-hydroxyethane-1,1-diphosphonic acid tetrasodium salt, disodium edetate, and trisodium edetate. , Tetrasodium edetate, citric acid, sodium citrate, sodium polyphosphate, sodium metaphosphate, gluconic acid, phosphoric acid, ascorbic acid, succinic acid, edetic acid, lactic acid, sodium lactate solution, etc. Is not to be done.

Examples of the buffer used in the liquid cosmetic include phosphates such as sodium phosphate and potassium phosphate, and organic acid salts such as sodium ascorbate and sodium benzoate, but are not limited thereto. Absent.
Furthermore, the silica composite polymer particles of the present invention can be used as a raw material for a light guide plate. The light guide plate includes a transparent base resin and silica composite polymer particles dispersed in the transparent base resin.

The transparent base resin and the silica composite polymer particles are preferably made of a material having a refractive index difference of less than 0.01 between the transparent base resin and the polymer particles in the silica composite polymer particles. A difference in refractive index of 0.01 or more is not preferable because the light diffusibility of the light guide plate is increased (total light transmittance is decreased), and the luminance of emitted light is decreased. A more preferable refractive index difference is less than 0.006. The lower limit of the refractive index difference is 0.
The inventor has found that the light guide plate including the silica composite polymer particles can exhibit uniform and high luminance as compared with the conventional light guide plate including inorganic particles such as alumina and transparent resin particles.

  In the light guide plate, the compounding ratio of the silica composite polymer particles is preferably 0.01 to 20 parts by weight with respect to 100 parts by weight of the transparent base resin. If the blending ratio is 0.01 parts by weight or more and the particles in which the silica component is unevenly distributed in a specific shape as described above, the effect of improving the luminance is satisfactorily exhibited. Moreover, if the mixing ratio is up to 20 parts by weight and the particles in which the silica component is unevenly distributed as described above are used, the light incident from the light source is perpendicular to the light emitting surface in the vicinity of the light source. It is possible to reduce the rate of conversion to the side, and it is possible to sufficiently reach the light to the central portion of the light guide plate. As a result, the light emission distribution on the light emitting surface can be appropriately balanced. Such an appropriate balance is desired particularly in a large liquid crystal display device of 15 inches or more. Furthermore, if the mixing ratio is up to 20 parts by weight and the particles in which the silica component is unevenly distributed in a unique shape as described above, there is little change in color tone near the light source of the light guide plate due to scattering, and within the light emitting surface The color tone distribution of the emitted light can be suppressed. A more preferable blending ratio is 0.03 to 15 parts by weight.

  Moreover, it is preferable that the silica component in a silica composite polymer particle is contained in the light-guide plate in 0.001-15 weight part with respect to 100 weight part of light-guide plates, 0.005-10 weight More preferably, it is contained within the range of parts. When the silica component is contained in this range and the silica component is unevenly distributed in the particles as described above, the light guide property and the light diffusibility can be achieved at a high level.

  The light guide plate usually comprises a light emitting surface, an opposite surface facing the light emitting surface, and a side surface defined by the light emitting surface and the opposite surface. For example, a light source for causing light to enter the light guide plate is disposed on a side surface of a liquid crystal display device of a notebook personal computer or a thin liquid crystal TV. Specifically, when the light emitting surface is a square and there are four corresponding side surfaces, the light source may be arranged on at least one side surface. In addition, a pair of light sources may be arranged on two opposing side surfaces, or a light source may be arranged on all four side surfaces. The wavelength of light guided and diffused in the light guide plate may be in the visible light region, the infrared region, or the ultraviolet region. In particular, in the use of a liquid crystal display device, it is preferable to include at least a visible light region.

  The shape of the light guide plate is not particularly limited, and can be appropriately determined according to the intended use. For example, examples of the shape of the light emitting surface include a rectangle, a square, a polygon, a circle, and an ellipse. Specifically, the length of the side surface perpendicular to the light emitting surface is preferably 1: 500 to 1: 4 with respect to the maximum length of the light emitting surface. More specifically, the length of the side surface is preferably 1 to 5 mm, and the maximum length of the light emitting surface is preferably 2 to 50 cm.

The light guide plate can be usually obtained by molding a kneaded product obtained by melt-kneading silica composite polymer particles and a transparent base resin into a desired shape by extrusion molding, injection molding or the like. Here, since the silica composite polymer particles have good dispersibility with respect to the transparent base resin, they can be mixed uniformly without particularly setting the kneading conditions severely.
As the transparent base resin constituting the constituent material of the light guide plate, the same kind of resin as the light diffusion plate can be used.

  Further, the light guide plate is usually used in a liquid crystal display device. The configuration of the liquid crystal display device is not particularly limited as long as it includes the light guide plate. For example, the liquid crystal display device includes at least a liquid crystal display panel having a display surface and a back surface, a light guide plate disposed on the back surface side of the panel, and a light source that makes light incident on a side surface of the light guide plate. In addition, a reflection sheet is provided on the side of the light guide plate opposite to the surface facing the liquid crystal display panel. This arrangement of light sources is generally referred to as an edge light type backlight arrangement.

The liquid crystal display panel has a configuration in which a liquid crystal layer is sandwiched between a pair of substrates. On the liquid crystal layer side of the substrate, an electrode and an alignment film covering the electrode are provided. Here, the electrode may include a thin film transistor. Further, the liquid crystal display panel may include a polarizing sheet, an antireflection sheet, and the like.
A diffusion sheet, a prism sheet, or the like may be disposed on the light emitting surface of the light guide plate on the liquid crystal panel side. In addition, a reflective sheet may be disposed on the back surface facing the light emitting surface.

Hereinafter, although an example and a comparative example explain the present invention, the present invention is not limited to this. In addition, the evaluation method of each property in an Example and a comparative example is described below.
(Measurement of average particle size)
The average particle diameter is a value measured with Multisizer II (manufactured by Beckman Coulter). The value is measured by calibrating with a 50 μm aperture according to Reference MANUAL FOR THE COULTER MULTISIZER (1987) published by Coulter Electronics Limited.
Specifically, 0.1 g of particles were predispersed in 10 ml of a 0.1% nonionic surfactant solution using a touch mixer and ultrasonic waves, and this was equipped with an ISOTON II (manufactured by Beckman Coulter, Inc .: measurement) In a beaker filled with an electrolytic solution), dripping with a dropper while gently stirring, adjust the reading of the densitometer on the main body screen to about 10%. Next, an aperture size of 50 μm, a current of 800, a gain of 4, and a polarity of + are input to the Multisizer II main body (the aperture size and the like can be changed as required) and measured manually. During the measurement, the beaker is stirred gently to the extent that bubbles do not enter, and the measurement is terminated when 100,000 particles are measured. The average particle diameter is an average value of the measured values.

(Measurement of reflected light intensity)
Adhere double-sided tape to black-and-white concealment test paper (manufactured by Toyo Seiki Co., Ltd.) so that air does not enter. Apply to the adhesive side of the double-sided tape while spreading the particles uniformly with a cosmetic puff. Excess particles are thoroughly swept away using a brush to obtain a sample. The obtained sample is measured with a three-dimensional photometer (Goniophotometer GP-200, manufactured by Murakami Color Research Co., Ltd.), and the reflected light intensity distribution at a reflection angle of −90 to 90 ° when the incident angle is −45 °.
From the reflected light intensity distribution, the light intensity at a reflection angle of 0 ° is calculated with the peak light intensity in the regular reflection direction (45 °) as 100. This means that the closer the light intensity is to 100, the more the light intensity of the reflected light does not change in the regular reflection direction or in the diffuse reflection direction, and it is defined that the diffusibility of the reflected light is large.

(Refractive index measurement method)
(1) Refractive index measurement method for polymer particles in silica composite polymer particles 0.001 g of particles are placed on a slide glass, and the refraction selected arbitrarily by the publication “Atago Refractometer Data Book” (published by Atago Co., Ltd.) Disperse the particles with 0.2 ml liquid organic compound at a rate to make a sample plate.
Next, each sample plate was set in an optical microscope and observed using a sodium lamp as a light source, and it was confirmed that the outline of the particles became invisible at a temperature where the refractive index of each liquid organic compound was known. Let the refractive index of a liquid organic compound be a refractive index of particle | grains.
In addition, as a liquid organic compound and its refractive index, the above-mentioned publication includes, for example,
“Furifurylamine (17 ° C.): refractive index 1.4900,
p-diethylbenzene ... refractive index 1.4948 "
However, the refractive index is rounded off to the fourth decimal place. In addition, for the case where the temperature is not particularly described such as p-diethylbenzene, the presence or absence of the outline of the particle is confirmed at 20 ° C.
In the following examples, using a monomer composition separately prepared in the same manner as in each example, each monomer was radical polymerized into polymer particles, and then the polymer particles were taken out without condensing the polysiloxane oligomer, The refractive index is measured as described above for polymer particles that have been washed with toluene and the polysiloxane oligomer has been completely washed away.

(2) Method for measuring refractive index of transparent base resin A material obtained by pulverizing a transparent base resin into particles (about 1 mg or less per particle) is measured by the same method as in the case of the silica composite polymer particles.

(Measurement method of aperture ratio)
First, 1 g of silica-coated polymer particles was taken in a 50-ml magnetic crucible, and calcined at 500 ° C. for 2 hours using an electric furnace (manufactured by ISUZU) to obtain silica-coated polymer particles. Particles having only the silica portion (hereinafter referred to as silica particles).
Next, the silica particles are gently taken out from the inside of the magnetic crucible with a spatula, and a photograph is taken with a scanning electron microscope (manufactured by JEOL Ltd .: GMS-820-A).
Furthermore, from the photographed photograph, arbitrary 50 pieces having an opening portion of silica particles on the top are selected, and each of them is manually measured by using a trace measurement of an image analysis apparatus (made by OMRON: Image-Ana LITE). The contour of the silica particle and the contour of the opening are designated, and the projected area (S2) and the area of the opening (S1) of the silica particle are measured.
From each measured area, the aperture ratio of each silica particle is obtained by the following formula. The aperture ratio is an average value of 50 silica particles.
Opening ratio = area of the opening of silica particles (S1) ÷ projected area of silica particles (S2)

(Measurement of h / D of silica particles)
As shown in FIG. 1, the value of h / D when the diameter of the silica particles is D and the height of the silica particles is h is measured by the following method.
In the same manner as the aperture ratio measurement method, a scanning electron micrograph of silica particles is taken, and 50 particles whose silica particle opening surface is perpendicular to the imaging surface are selected from the photographed images. To do. The value of D and h of each particle is measured by the image analysis apparatus, and h / D is calculated. In this specification, h / D means an average value of 50 h / Ds.

(Total light transmittance)
The total light transmittance of the molded body is measured according to JIS K7105 using a haze meter (“NDH-2000” manufactured by Nippon Denshoku).

(Dispersity D50)
Using a 2 mm portion of the plate, the light diffusivity (D50) is determined by the following procedure using an automatic goniophotometer (Goniophotometer GP-1R manufactured by Murakami Color Research Laboratory).
A straight beam from the light source of the automatic goniophotometer is applied from the normal direction of the molded body placed at a distance of 75 cm from the light source. The intensity of light transmitted through the molded body is measured with a movable light receiver. This intensity is converted into transmittance, and the transmittance is plotted on a graph corresponding to the angle from the normal direction. From this graph, the angle at which the transmittance of light in the normal direction (straight light transmittance) is 50% is obtained. This angle is referred to as the degree of dispersion D50, and the unit is “degree”. Moreover, it means that it is excellent in diffusibility, so that D50 is large.

(Examples and comparative examples of silica composite polymer particles)
Example 1
A dispersion medium (aqueous suspension) in which 250 g of Snowtex O-40 (manufactured by Nissan Chemical Industries, Ltd .: 40% by weight aqueous colloidal silica having an average particle size of 20 to 30 nm) as a colloidal silica was mixed with 1750 g of water was stirred. Placed in polymerization vessel with equipment.

Separately, 700 g of methyl methacrylate as a monofunctional polymerizable vinyl monomer and 300 g of MKC silicate MS57 (manufactured by Mitsubishi Chemical Corporation: average molecular weight 1300 to 1500, R is methyl, n is 15 to 18 in average) as a polyalkoxysiloxane oligomer Then, a mixture prepared by uniformly dissolving 0.5 g of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator was prepared.
This mixture was added to the dispersion medium and stirred at 7,000 rpm for about 10 minutes with a homomixer to finely disperse the mixture.

  Thereafter, stirring is continued at a stirring speed of 300 rpm, and the polymerization vinyl monomer is polymerized by performing suspension polymerization for 4 hours after the temperature of the dispersion medium added with the mixture reaches 60 ° C. 60 g of sodium pyrophosphate was added to condense the polyalkoxysiloxane oligomer.

  Next, the reaction liquid in the polymerization vessel was cooled to room temperature (about 30 ° C.) while stirring to obtain silica composite polymer particles in which the surface of the polymer component was locally coated with the silica component derived from the polyalkoxysiloxane oligomer. . The target particles were taken out by dehydrating and drying the obtained particles. The average particle diameter of the obtained silica composite polymer particles is 8.6 μm. Table 1 shows the measurement results of luminous intensity at a reflection angle of 0 °.

  In order to confirm the composite state of the polymer component and the silica component, the silica composite polymer particles were baked in an electric furnace at 500 ° C. to remove the polymer component, thereby obtaining silica particles. The shape of the obtained silica particles was observed with an electron micrograph. The shape of the silica particles had a shape with a spherical protrusion (seed) inside the hemisphere bowl. Therefore, the silica component was unevenly distributed in the silica composite polymer particle, in other words, the first silica component corresponding to the outer shell portion of the silica particle located on the surface of the silica composite polymer particle and the surface layer. And it was confirmed that it was composed of a second silica component corresponding to the inner shell portion of the silica particles forming the convex portion toward the center of the silica composite polymer particle. An electron micrograph is shown in FIG.

  Table 1 also shows the types and amounts of the polymerizable vinyl monomers, polyalkoxysiloxane oligomers and colloidal silica used, the silica particle opening ratio, and h / D. The amount of colloidal silica used means% by weight based on the dispersion medium (the same applies hereinafter). Further, a graph of the reflected light intensity distribution is shown in FIG.

Example 2
In Example 1, silica composite polymer particles were obtained in the same manner as in Example 1 except that 900 g of methyl methacrylate and 100 g of MKC silicate MS57 were used. The average particle diameter of the obtained particles was 8.1 μm. Table 1 shows the measurement results of luminous intensity at a reflection angle of 0 °. When fired in the same manner as in Example 1, the shape of the silica particles has a shape with spherical protrusions inside the hemispherical bowl, and the silica component is unevenly distributed in the silica composite polymer particles as in Example 1. I was able to confirm. An electron micrograph is shown in FIG.
Table 1 also shows the types and amounts of the polymerizable vinyl monomers, polyalkoxysiloxane oligomers and colloidal silica used, the silica particle opening ratio, and h / D. Further, a graph of the reflected light intensity distribution is shown in FIG.

Example 3
In Example 1, silica composite polymer particles were obtained in the same manner as in Example 1 except that 200 g of methyl methacrylate and 800 g of MKC silicate MS57 were used. The average particle diameter of the obtained particles was 7.9 μm. Table 1 shows the measurement results of luminous intensity at a reflection angle of 0 °. When fired in the same manner as in Example 1, the shape of the silica particles has a shape with spherical protrusions inside the hemispherical bowl, and the silica component is unevenly distributed in the silica composite polymer particles as in Example 1. I was able to confirm. An electron micrograph is shown in FIG.
Table 1 also shows the types and amounts of the polymerizable vinyl monomers, polyalkoxysiloxane oligomers and colloidal silica used, the silica particle opening ratio, and h / D.

Example 4
In Example 1, silica composite polymer particles were obtained in the same manner as in Example 1 except that Snowtex OL (manufactured by Nissan Chemical Co., Ltd .: 20% by weight aqueous colloidal silica solution having an average particle size of 40 to 50 nm) was used as colloidal silica. Got. The average particle diameter of the obtained particles was 8.2 μm. Table 1 shows the measurement results of luminous intensity at a reflection angle of 0 °. When fired in the same manner as in Example 1, the shape of the silica particles has a shape with spherical protrusions inside the hemispherical bowl, and the silica component is unevenly distributed in the silica composite polymer particles as in Example 1. I was able to confirm.
Table 1 also shows the types and amounts of the polymerizable vinyl monomers, polyalkoxysiloxane oligomers and colloidal silica used, the silica particle opening ratio, and h / D.

Example 5
In Example 1, the same procedure as in Example 1 was used except that MKC silicate MS51 (manufactured by Mitsubishi Chemical Corporation: average molecular weight 500 to 700, R is methyl, and n average is 5 to 10) was used as the polyalkoxysiloxane oligomer. Silica composite polymer particles were obtained. The average particle diameter of the obtained particles was 8.6 μm. Table 1 shows the measurement results of luminous intensity at a reflection angle of 0 °. When fired in the same manner as in Example 1, the shape of the silica particles has a shape with spherical protrusions inside the hemispherical bowl, and the silica component is unevenly distributed in the silica composite polymer particles as in Example 1. I was able to confirm.
Table 1 also shows the types and amounts of the polymerizable vinyl monomers, polyalkoxysiloxane oligomers and colloidal silica used, the silica particle opening ratio, and h / D.

Example 6
In Example 1, MKC silicate MS58B15 (manufactured by Mitsubishi Chemical Corporation: average molecular weight 1600 to 1800, R is butyl, n is 11 to 13) is used in the same manner as in Example 1 as the polyalkoxysiloxane oligomer. Silica composite polymer particles were obtained. The average particle diameter of the obtained particles was 8.5 μm. Table 1 shows the measurement results of luminous intensity at a reflection angle of 0 °. When fired in the same manner as in Example 1, the shape of the silica particles has a shape with spherical protrusions inside the hemispherical bowl, and the silica component is unevenly distributed in the silica composite polymer particles as in Example 1. I was able to confirm.
Table 1 also shows the types and amounts of the polymerizable vinyl monomers, polyalkoxysiloxane oligomers and colloidal silica used, the silica particle opening ratio, and h / D.

Example 7
Silica composite polymer particles were obtained in the same manner as in Example 1 except that Quarton PL-3 (manufactured by Fuso Chemical Industry Co., Ltd .: aqueous colloidal silica 20 wt% solution with an average particle size of 35 nm) was used as the colloidal silica. The average particle diameter of the obtained particles was 7.5 μm. Table 1 shows the measurement results of luminous intensity at a reflection angle of 0 °. When fired in the same manner as in Example 1, the shape of the silica particles has a shape with spherical protrusions inside the hemispherical bowl, and the silica component is unevenly distributed in the silica composite polymer particles as in Example 1. I was able to confirm. An electron micrograph is shown in FIG.
Table 1 also shows the types and amounts of the polymerizable vinyl monomers, polyalkoxysiloxane oligomers and colloidal silica used, the silica particle opening ratio, and h / D.

Example 8
Silica composite polymer particles were obtained in the same manner as in Example 1 except that Quarton PL-7 (manufactured by Fuso Chemical Industry Co., Ltd .: aqueous colloidal silica 20 wt% solution with an average particle diameter of 70 nm) was used as colloidal silica. The average particle diameter of the obtained particles was 8.9 μm. Table 1 shows the measurement results of luminous intensity at a reflection angle of 0 °. When fired in the same manner as in Example 1, the shape of the silica particles has a shape with spherical protrusions inside the hemispherical bowl, and the silica component is unevenly distributed in the silica composite polymer particles as in Example 1. I was able to confirm.
Table 1 also shows the types and amounts of the polymerizable vinyl monomers, polyalkoxysiloxane oligomers and colloidal silica used, the silica particle opening ratio, and h / D.

Example 9
Silica composite polymer particles were obtained in the same manner as in Example 1 except that 25 g of acetic acid was used instead of sodium pyrophosphate. The average particle diameter of the obtained particles was 8.3 μm. Table 1 shows the measurement results of luminous intensity at a reflection angle of 0 °. When fired in the same manner as in Example 1, the shape of the silica particles has a shape with spherical protrusions inside the hemispherical bowl, and the silica component is unevenly distributed in the silica composite polymer particles as in Example 1. I was able to confirm.
Table 1 also shows the types and amounts of the polymerizable vinyl monomers, polyalkoxysiloxane oligomers and colloidal silica used, the silica particle opening ratio, and h / D.

Example 10
Silica composite polymer particles were obtained in the same manner as in Example 1 except that 500 g of styrene and 500 g of MKC silicate MS57 were used instead of 700 g of methyl methacrylate. The average particle diameter of the obtained particles was 8.7 μm. Table 1 shows the measurement results of luminous intensity at a reflection angle of 0 °. When fired in the same manner as in Example 1, the shape of the silica particles has a shape with spherical protrusions inside the hemispherical bowl, and the silica component is unevenly distributed in the silica composite polymer particles as in Example 1. I was able to confirm.
Table 1 also shows the types and amounts of the polymerizable vinyl monomers, polyalkoxysiloxane oligomers and colloidal silica used, the silica particle opening ratio, and h / D.

Example 11
Silica composite polymer particles were obtained in the same manner as in Example 1 except that 1000 g of Snowtex O-40 was used for 1400 g of water. The average particle diameter of the obtained particles was 8.1 μm. Table 1 shows the measurement results of luminous intensity at a reflection angle of 0 °. When fired in the same manner as in Example 1, the shape of the silica particles has a shape with spherical protrusions inside the hemispherical bowl, and the silica component is unevenly distributed in the silica composite polymer particles as in Example 1. I was able to confirm. An electron micrograph is shown in FIG.
Table 1 also shows the types and amounts of the polymerizable vinyl monomers, polyalkoxysiloxane oligomers and colloidal silica used, the silica particle opening ratio, and h / D.

Example 12
Silica composite polymer particles were obtained in the same manner as in Example 1 except that the rotation speed of the homomixer was 10,000 rpm. The average particle diameter of the obtained particles was 3 μm. Table 1 shows the measurement results of luminous intensity at a reflection angle of 0 °. When fired in the same manner as in Example 1, the shape of the silica particles has a shape with spherical protrusions inside the hemispherical bowl, and the silica component is unevenly distributed in the silica composite polymer particles as in Example 1. I was able to confirm. An electron micrograph is shown in FIG.
Table 1 also shows the types and amounts of the polymerizable vinyl monomers, polyalkoxysiloxane oligomers and colloidal silica used, the silica particle opening ratio, and h / D.

Example 13
Silica composite polymer particles were obtained in the same manner as in Example 12 except that 490 g of styrene and 210 g of ethylene glycol dimethacrylate were used as the polymerizable vinyl monomer. The average particle diameter of the obtained particles was 4 μm. Table 1 shows the measurement results of luminous intensity at a reflection angle of 0 °. When fired in the same manner as in Example 1, the shape of the silica particles has a shape with spherical protrusions inside the hemispherical bowl, and the silica component is unevenly distributed in the silica composite polymer particles as in Example 1. I was able to confirm. An electron micrograph is shown in FIG.
Table 1 also shows the types and amounts of the polymerizable vinyl monomers, polyalkoxysiloxane oligomers and colloidal silica used, the silica particle opening ratio, and h / D.

Example 14
Silica composite polymer particles were obtained in the same manner as in Example 12 except that MKC silicate MS51 was used as the polyalkoxysiloxane oligomer. The average particle diameter of the obtained particles was 3.5 μm. Table 1 shows the measurement results of luminous intensity at a reflection angle of 0 °. When fired in the same manner as in Example 1, the shape of the silica particles has a shape with spherical protrusions inside the hemispherical bowl, and the silica component is unevenly distributed in the silica composite polymer particles as in Example 1. I was able to confirm. An electron micrograph is shown in FIG.
Table 1 also shows the types and amounts of the polymerizable vinyl monomers, polyalkoxysiloxane oligomers and colloidal silica used, the silica particle opening ratio, and h / D.

Example 15
Silica composite polymer particles were obtained in the same manner as in Example 12 except that 165 g of methyl methacrylate, 90 g of ethylene glycol dimethacrylate and 45 g of styrene were used as a polymerizable vinyl monomer, and 700 g of a polyalkoxysiloxane oligomer was used. . The average particle diameter of the obtained particles was 3.2 μm. Table 1 shows the measurement results of luminous intensity at a reflection angle of 0 °. When fired in the same manner as in Example 1, the shape of the silica particles has a shape with spherical protrusions inside the hemispherical bowl, and the silica component is unevenly distributed in the silica composite polymer particles as in Example 1. I was able to confirm. An electron micrograph is shown in FIG.
Table 1 also shows the types and amounts of the polymerizable vinyl monomers, polyalkoxysiloxane oligomers and colloidal silica used, the silica particle opening ratio, and h / D.

Example 16
Silica composite polymer particles were obtained in the same manner as in Example 12 except that 300 g of trifluoroethyl methacrylate and 175 g of ethylene glycol dimethacrylate were used as the polymerizable vinyl monomer. The average particle diameter of the obtained particles was 3.5 μm. Table 1 shows the measurement results of luminous intensity at a reflection angle of 0 °. When fired in the same manner as in Example 1, the shape of the silica particles has a shape with spherical protrusions inside the hemispherical bowl, and the silica component is unevenly distributed in the silica composite polymer particles as in Example 1. I was able to confirm.
Table 1 also shows the types and amounts of the polymerizable vinyl monomers, polyalkoxysiloxane oligomers and colloidal silica used, the silica particle opening ratio, and h / D.

Example 17
Silica composite polymer particles were obtained in the same manner as in Example 12 except that 300 g of trifluoroethyl methacrylate and 700 g of MKC silicate were used as the polymerizable vinyl monomer. The average particle diameter of the obtained particles was 3.5 μm. Table 1 shows the measurement results of luminous intensity at a reflection angle of 0 °. When fired in the same manner as in Example 1, the shape of the silica particles has a shape with spherical protrusions inside the hemispherical bowl, and the silica component is unevenly distributed in the silica composite polymer particles as in Example 1. I was able to confirm.
Table 1 also shows the types and amounts of the polymerizable vinyl monomers, polyalkoxysiloxane oligomers and colloidal silica used, the silica particle opening ratio, and h / D.

Comparative Example 1
In the same manner as in Example 1 except that γ-methacryloxypropyltrimethoxysilane having a polymerizable property with a polymerizable vinyl monomer was used instead of the polyalkoxysiloxane oligomer (manufactured by Toray Dow Corning Silicone Co., Ltd .: SZ6030). Particles were obtained (average particle size 7.9 μm). In the obtained particles, the polymer component was uniformly dispersed in the particles. The measurement results of luminous intensity at a reflection angle of 0 ° are shown in Table 2.
Table 2 also shows the types and amounts of the polymerizable vinyl monomers, siloxanes and colloidal silica used.

Comparative Example 2
Particles were obtained in the same manner as in Example 1 except that 950 g of methyl methacrylate and 50 g of MKC silicate MS57 were used (average particle diameter: 7.8 μm).
When fired in the same manner as in Example 1, the silica particles could not form a bowl and had an indeterminate shape. An electron micrograph is shown in FIG.
Table 2 shows the types and amounts of the polymerizable vinyl monomers, siloxanes and colloidal silica used.

Comparative Example 3
Particles were obtained in the same manner as in Example 1 except that 50 g of methyl methacrylate and 950 g of MKC silicate MS57 were used. The obtained particles were not spherical but had an irregular shape. As a result of firing in the same manner as in Example 1, no evidence of the uneven distribution of the silica component in the particles was found.
Table 2 shows the types and amounts of the polymerizable vinyl monomers, siloxanes and colloidal silica used.

Comparative Example 4
Particles were obtained in the same manner as in Example 1 except that Snowtex MP1040 (manufactured by Nissan Chemical Industries, Ltd .: aqueous colloidal silica 40 wt% solution having an average particle diameter of 100 nm) was used as the colloidal silica (average particle diameter 20.2 μm). The measurement results of luminous intensity at a reflection angle of 0 ° are shown in Table 2. When fired in the same manner as in Example 1, it can be seen that the shape of the silica particles was a bowl shape without protrusions inside, and the silica component covered the polymer component.
Table 2 also shows the types and amounts of the polymerizable vinyl monomer, siloxane and colloidal silica used, the silica particle opening ratio, and h / D. Further, a graph of the reflected light intensity distribution is shown in FIG.

Comparative Example 5
A hybrid resin (manufactured by Nara Machinery Co., Ltd.) of 21 g of acrylic resin particles having an average particle diameter of 8 μm (MB-8, manufactured by Sekisui Plastics Industries Co., Ltd.) and 9 g of Aerosil R972 (manufactured by Nippon Aerosil Co., Ltd., average particle diameter of 16 nm) at 50 ° The treatment was carried out at 14000 rpm for 5 minutes to obtain composite polymer particles whose surface was coated with silica particles (average particle size: 8.9 μm). The measurement results of luminous intensity at a reflection angle of 0 ° are shown in Table 2.

Comparative Example 6
A dispersion medium in which 50 g of magnesium pyrophosphate by metathesis method is mixed with 2000 g of water as a suspension stabilizer is placed in a polymerization vessel having a stirrer. Sodium nitrate (0.2 g) was dissolved in the dispersion medium.

Separately, 700 g of methyl methacrylate as a monofunctional polymerizable vinyl monomer, 300 g of MKC silicate MS57 as a polyalkoxysiloxane oligomer, and 0.5 g of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator The mixture which melt | dissolved uniformly was prepared.
This mixture was added to the dispersion medium and stirred at 7,000 rpm for about 10 minutes with a homomixer to finely disperse the mixture.

Thereafter, stirring is continued at a stirring speed of 300 rpm, and the polymer component is obtained by polymerizing the polymerizable vinyl monomer by performing suspension polymerization for 4 hours after the temperature of the dispersion medium to which the mixture is added reaches 60 ° C., Further, 20 g of sodium hydroxide was added to condense the polyalkoxysiloxane oligomer.
Next, the reaction solution in the polymerization vessel was cooled to room temperature while stirring, and hydrochloric acid was added until the pH of the slurry was about 2, whereby the suspension stabilizer was decomposed to obtain silica composite polymer particles. The target particles were taken out by dehydrating and drying the obtained particles (average particle diameter: 8.8 μm). The measurement results of luminous intensity at a reflection angle of 0 ° are shown in Table 2.

When fired in the same manner as in Example 1, it can be seen that the shape of the silica particles was a bowl shape without protrusions inside, and the silica component covered the polymer component.
Table 2 also shows the types and amounts of the polymerizable vinyl monomer and siloxane used, the silica particle opening ratio, and h / D. Further, a graph of the reflected light intensity distribution is shown in FIG.

Comparative Example 7
Particles were obtained in the same manner as in Example 5 except that 125 g of methyl methacrylate and 875 g of MKC silicate MS57 were used. The obtained particles were not spherical but had an irregular shape. As a result of firing in the same manner as in Example 1, no evidence of the uneven distribution of the silica component in the particles was found.
Table 2 shows the types and amounts of the polymerizable vinyl monomers, siloxanes and colloidal silica used.

Comparative Example 8
Particles were obtained in the same manner as in Comparative Example 6 except that 560 g of methyl methacrylate and 240 g of ethylene glycol dimethacrylate were used as monofunctional polymerizable vinyl monomers, and the homomixer was rotated at 10,000 rpm ( Average particle diameter 4.7 μm). The measurement results of luminous intensity at a reflection angle of 0 ° are shown in Table 2. When fired in the same manner as in Example 1, it can be seen that the shape of the silica particles was a bowl shape without protrusions inside, and the silica component covered the polymer component.
Table 2 also shows the types and amounts of the polymerizable vinyl monomer and siloxane used, the silica particle opening ratio, and h / D.

Comparative Example 9
In the same manner as in Example 12, except that γ-methacryloxypropyltrimethoxysilane having a polymerizability with a polymerizable vinyl monomer was used instead of the polyalkoxysiloxane oligomer (manufactured by Toray Dow Corning Silicone Co., Ltd .: SZ6030). Particles were obtained (average particle size 5.0 μm). In the obtained particles, the polymer component was uniformly dispersed in the particles. The measurement results of luminous intensity at a reflection angle of 0 ° are shown in Table 2.
Table 2 also shows the types and amounts of the polymerizable vinyl monomers, siloxanes and colloidal silica used.

Comparative Example 10
In a polymerization vessel equipped with a stirrer and a thermometer, 2000 g of deionized water in which 0.05 g of sodium lauryl phosphate was dissolved was added, and 50 g of tricalcium phosphate was added and dispersed. Next, a mixed solution prepared by dissolving 5 g of benzoyl peroxide and 0.5 g of azobisisobutyronitrile in 700 g of styrene, which is a polymerizable vinyl monomer, and 300 g of ethylene glycol dimethacrylate, was placed in a polymerization vessel. Dispersion was performed using a K homomixer, and droplets were adjusted to about 5 μm. Next, the inside of the polymerization vessel was heated to 65 ° C. and subjected to suspension polymerization while stirring, and then cooled. The suspension was filtered and washed, and then dried to obtain particles made of a true spherical polymer (average particle size 5 μm). The measurement results of luminous intensity at a reflection angle of 0 ° are shown in Table 2.

Comparative Example 11
Silica composite polymer particles are obtained in the same manner as in Example 1 except that methanol silica sol (manufactured by Nissan Chemical Industries, Ltd .: methanol solution with an average particle size of 15 nm and a silica content of 30% by weight) is used as colloidal silica. (Average particle size 8.2 μm). The measurement results of luminous intensity at a reflection angle of 0 ° are shown in Table 2.
When fired in the same manner as in Example 1, it can be seen that the shape of the silica particles was a bowl shape without protrusions inside, and the silica component covered the polymer component. The measurement results of luminous intensity at a reflection angle of 0 ° are shown in Table 2.
Table 2 also shows the types and amounts of the polymerizable vinyl monomer, siloxane and colloidal silica used, the silica particle opening ratio, and h / D.

Comparative Example 12
Silica composite polymer particles were obtained in the same manner as in Example 1 except that IPA-ST (manufactured by Nissan Chemical Industries, Ltd .: isopropanol solution having an average particle size of 15 nm and a silica content of 30% by weight) was used as colloidal silica. Obtained (average particle size 7.3 μm). The measurement results of luminous intensity at a reflection angle of 0 ° are shown in Table 2.
When fired in the same manner as in Example 1, it can be seen that the shape of the silica particles was a bowl shape without protrusions inside, and the silica component covered the polymer component. The measurement results of luminous intensity at a reflection angle of 0 ° are shown in Table 2.
Table 2 also shows the types and amounts of the polymerizable vinyl monomer, siloxane and colloidal silica used, the silica particle opening ratio, and h / D.

Comparative Example 13
Silica composite polymer particles in the same manner as in Example 1, except that EG-ST (manufactured by Nissan Chemical Industries, Ltd .: ethylene glycol solution having an average particle size of 15 nm and a silica content of 30% by weight) as an organosilica sol was used as colloidal silica. However, there was no dispersion stability of the monomer mixture in the suspension, and particles could not be obtained.
Table 2 also shows the types and amounts of the polymerizable vinyl monomers, siloxanes and colloidal silica used.

Comparative Example 14
The silica composite polymer particles were prepared in the same manner as in Example 1 except that MEK-ST (manufactured by Nissan Chemical Industries, Ltd .: methyl ethyl ketone solution having an average particle diameter of 15 nm and a silica content of 30% by weight) was used as colloidal silica. Production was attempted, but the dispersion of the monomer mixture in the suspension was not stable, and particles could not be obtained.
Table 2 also shows the types and amounts of the polymerizable vinyl monomers, siloxanes and colloidal silica used.

  In Tables 1 and 2, MMA means methyl methacrylate, ST means styrene, EGDMA means ethylene glycol dimethacrylate, and TFEMA means trifluoroethyl methacrylate.

From Tables 1 and 2, the silica composite polymer particles of Examples 1 to 17 have a higher luminous intensity at a reflection angle of 0 ° than the silica composite polymer particles obtained by simply coating the silica component on the inorganic particles alone or the polymer particles. all right.
The luminous intensity at a reflection angle of 20 ° obtained from FIGS. 6, 8, 17 and 18 is 95.0 in Example 1, 98.7 in Example 2, 72.4 in Comparative Example 4, and 75 in Comparative Example 6. .8. From these results, Examples 1 and 2 have a small difference in luminous intensity between reflection angles of 20 ° and 0 °, while Comparative Examples 4 and 6 have a large difference. Therefore, it was found that the silica composite polymer particles of Examples 1 and 2 were less biased in the light diffusion direction than the particles of Comparative Examples 4 and 6.

(Examples and comparative examples of light diffusion plates)
Example A
3 g of the silica composite polymer particles (light diffusing particles) of Example 12 were added to 300 g of (meth) acrylic acid alkyl-styrene copolymer resin (Estyrene MS200 manufactured by Nippon Steel Chemical Co., Ltd.), and 3 minutes in a food mixer. After blending, the mixture was supplied to an injection molding machine and injection molded to obtain a light diffusing plate having a length of 100 mm, a width of 50 mm, and a thickness of 2 mm. The total light transmittance and dispersion degree D50 of this light diffusion plate were measured. The results are shown in Table 3 below.

Example B
A light diffusing plate was obtained in the same manner as in Example A except that the amount of the light diffusing particles added was 9 g with respect to 300 g of the (meth) acrylic acid alkyl-styrene copolymer resin. Further, in the same manner as in Example A, the total light transmittance and the degree of dispersion of this light diffusion plate were measured. The results are shown in Table 3 below.

Example C
A light diffusing plate was obtained in the same manner as in Example A except that 6 g of the light diffusing particles of Example 13 was used with respect to 300 g of methyl methacrylate resin (Sumitex EXA manufactured by Sumitomo Chemical Co., Ltd.). Further, in the same manner as in Example A, the total light transmittance and the degree of dispersion of this light diffusion plate were measured. The results are shown in Table 3 below.

Example D
A light diffusing plate was obtained in the same manner as in Example A except that the light diffusing particles of Example 14 were used. Further, in the same manner as in Example A, the total light transmittance and the degree of dispersion of this light diffusion plate were measured. The results are shown in Table 3 below.

Example E
A light diffusing plate was obtained in the same manner as in Example A except that the light diffusing particles of Example 15 were used. Further, in the same manner as in Example A, the total light transmittance and the degree of dispersion of this light diffusion plate were measured. The results are shown in Table 3 below.

Example F
A light diffusing plate was obtained in the same manner as in Example A except that 30 g of the light diffusing particles of Example 13 was used with respect to 300 g of polystyrene resin (Toyostyrene GP HRM40 manufactured by Toyo Styrene Co., Ltd.). Further, in the same manner as in Example A, the total light transmittance and the degree of dispersion of this light diffusion plate were measured. The results are shown in Table 3 below.

Example G
A light diffusing plate was obtained in the same manner as in Example A, except that 3 g of the light diffusing particle of Example 16 was used with respect to 300 g of polystyrene resin (Toyostyrene GP HRM40 manufactured by Toyo Styrene Co., Ltd.). Further, in the same manner as in Example A, the total light transmittance and the degree of dispersion of this light diffusion plate were measured. The results are shown in Table 3 below.

Comparative Example A
A light diffusing plate was obtained in the same manner as in Example A except that the light diffusing particles of Comparative Example 8 were used. Further, in the same manner as in Example A, the total light transmittance and the degree of dispersion of this light diffusion plate were measured. The results are shown in Table 3 below.

Comparative Example B
A light diffusing plate was obtained in the same manner as in Example A, except that 9 g of the light diffusing particles of Comparative Example 9 were used. Further, in the same manner as in Example A, the total light transmittance and the degree of dispersion of this light diffusion plate were measured. The results are shown in Table 3 below.

Comparative Example C
A light diffusing plate was obtained in the same manner as in Example A, except that 30 g of the light diffusing particles of Comparative Example 10 was used with respect to 300 g of methyl methacrylate resin (Sumipex EXA manufactured by Sumitomo Chemical Co., Ltd.). Further, in the same manner as in Example A, the total light transmittance and the degree of dispersion of this light diffusion plate were measured. The results are shown in Table 3 below.

Comparative Example D
A light diffusing plate was obtained in the same manner as in Example A, except that no light diffusing particles were blended and only methyl methacrylate resin (Sumitex EXA manufactured by Sumitomo Chemical Co., Ltd.) was used. Further, in the same manner as in Example A, the total light transmittance and the degree of dispersion of this light diffusion plate were measured. The results are shown in Table 3 below.

From Examples A to G and Comparative Example D, it can be seen that the light diffusing plate containing the light diffusing particles having a specific shape has high total light transmittance and degree of dispersion.
From Example A and Comparative Examples A and B, it can be seen that the dispersity can be further improved when the silica component has an inner shell portion.
From Comparative Example C, it can be seen that when light diffusing particles not containing a silica component are used, the degree of dispersion cannot be improved much even if added in a large amount to the light diffusing plate.

Claims (13)

In an aqueous suspension in which an aqueous colloidal silica having an average particle size of 90 nm or less is dispersed, 100 parts by weight of a polymerizable vinyl monomer selected from styrene, acrylic acid, methacrylic acid, derivatives thereof and mixtures thereof , and the polymerization After adding a mixture containing 10 to 500 parts by weight of a polyalkoxysiloxane oligomer inert to the polymerizable vinyl monomer and 0.01 to 10 parts by weight of a polymerization initiator, the polymerizable vinyl is subjected to aqueous suspension polymerization. Forming a polymer component derived from a monomer,
Next, an acid or base catalyst is added to the aqueous suspension after the aqueous suspension polymerization to form a silica component by condensation of the polyalkoxysiloxane oligomer, and silica composite polymer particles containing the polymer component and the silica component are obtained. A process for producing silica composite polymer particles.   The silica component is obtained by firing the silica composite polymer particles to remove the polymer component, and the silica particles are in contact with a spherical or substantially spherical outer shell portion having a hollow structure and the outer shell portion, and The method for producing silica composite polymer particles according to claim 1, wherein the silica composite polymer particles are unevenly distributed in the silica composite polymer particles so as to have an inner shell portion that forms a convex portion toward the center.   The method for producing silica composite polymer particles according to claim 1, wherein the aqueous colloidal silica is used in an aqueous suspension at a concentration of 0.5 to 20% by weight. The polyalkoxysiloxane oligomer has the following formula:
2 wherein R is the same or different and is CH ₃ , C ₂ H ₅ , C ₃ H ₇ or C ₄ H ₉ and 40>n> 2. A method for producing silica composite polymer particles. A silica composite polymer particle obtained by the production method according to claim 1, comprising a polymer component derived from a polymerizable vinyl monomer and a silica component,
The silica component is a condensate derived from a polyalkoxysiloxane oligomer that is inert to the polymerizable vinyl monomer, and
The silica component is obtained by firing the silica composite polymer particles to remove the polymer component, and the silica particles are in contact with a spherical or substantially spherical outer shell portion having a hollow structure and the outer shell portion, and Silica composite polymer particles that are unevenly distributed in the silica composite polymer particles so as to have an inner shell portion that forms a convex portion toward the center. The silica composite polymer particle according to claim 5 , wherein the silica component is contained in an amount of 10 to 500 parts by weight with respect to 100 parts by weight of the polymer component. The silica composite polymer particle according to claim 5 , wherein the silica composite polymer particle has a light intensity with a reflection angle of 0 ° of 70 or more, where the light intensity in the regular reflection direction of incident light of −45 ° is 100. 7.   The light diffusing plate containing a transparent resin base material and the silica composite polymer particle obtained by the manufacturing method of Claim 1. A light diffusing plate comprising the transparent base resin and light diffusing particles dispersed in the transparent base resin,
The light diffusion particle is a silica composite polymer particle containing a polymer component derived from a polymerizable vinyl monomer and a silica component,
The silica component is a condensate derived from a polyalkoxysiloxane oligomer that is inert to the polymerizable vinyl monomer, and
The silica component is obtained by firing the silica composite polymer particles to remove the polymer component, and the silica particles are in contact with a spherical or substantially spherical outer shell portion having a hollow structure and the outer shell portion, and The light diffusing plate according to claim 8 , wherein the light diffusing plate is unevenly distributed in the silica composite polymer particle so as to have an inner shell portion that forms a convex portion toward the center. The light diffusing plate according to claim 9 , wherein the light diffusing particles are contained in an amount of 0.1 to 20 parts by weight with respect to 100 parts by weight of the transparent base resin. The light diffusing plate according to claim 9 , wherein the light diffusing particles are dispersed in the transparent base resin so that light incident from the back surface of the light diffusing plate is diffused and taken out from the front surface. The light diffusing plate according to claim 9 , wherein the silica component is contained in a range of 0.01 to 15 parts by weight with respect to 100 parts by weight of the light diffusing plate. A liquid crystal display panel having a display surface and a back surface, a light source disposed on the back surface side, and a light diffusing plate according to claim 9 disposed between the liquid crystal display panel and the light source. A characteristic liquid crystal display device.