JPH10265580A - Silica composite resin particle, its production and use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide silica composite resin particles that does not lower the brightness of the plane emission of a light diffusion material because it is excellent in light diffusion and light transmission. SOLUTION: The objective silica composite resin particles are produced by dispersing fine particles of silica with an average particle size of <=500 nm in a clear or translucent resin. The light diffusion resin composition is produced by dispersing a light-diffusing agent of the silica composite resin particles in a clear or translucent resin and the light-diffusion sheet is produced by forming the light-diffusion resin composition to a sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to silica composite resin particles having excellent light diffusing properties, a method for producing the same, and uses thereof.

[0002]

2. Description of the Related Art Light diffusing materials are used for materials such as lighting covers and display screens from the viewpoint of effectively utilizing light emitted from a light source. As such a light diffusing material, there is a material in which fine particles made of an inorganic substance or an organic substance are used as a light diffusing agent and dispersed in a transparent resin as a base material. The principle is to utilize the difference in the refractive index between the fine particles and the transparent resin, and to diffuse the light in the transmission direction by refracting the light reaching the interface between the fine particles and the transparent resin.

In order to improve the light diffusing property of a light diffusing material, JP-A-60-139758 and JP-A-60-139758 have been proposed.
184,559 and the like disclose a light diffusing material in which the difference in refractive index between a transparent resin and a light diffusing agent is defined.
Japanese Patent Publication No. Sho 62-31741 discloses that SiO ₂ ,
Disclosed is a sheet-like material obtained by uniformly mixing a light diffusing agent having a particle diameter of several to several tens of μm comprising fine particles of any two kinds of CaCO ₃ and an organic polymer into a transparent resin. Have been.

In the light diffusing material described in the above publication, it is necessary to add a large amount of a light diffusing agent in order to improve the light diffusing property. However, when a large amount of the light diffusing agent is added, there arises a problem that the light transmittance of the light diffusing material is reduced and the luminance of the light emitting surface is also reduced. On the other hand, in a liquid crystal display device, a film-like light diffusing material for a liquid crystal backlight may be used. That is, a backlight illumination panel made of a film-like light diffusing material is arranged behind a liquid crystal display panel, and light from the backlight illumination panel is irradiated in front of the liquid crystal display panel to display a display image on the liquid crystal display panel. It makes it easier to see. JP-A-6-258504 discloses a film-like light-diffusing material used for such an application, which is formed on a transparent resin film having fine irregularities on both surfaces by coating a layer made of solid fine particles having a particle diameter of 10 μm or less (light A light diffusing film provided with a (diffusing agent layer) is disclosed. Further, Japanese Patent Application Laid-Open No. 6-273762 discloses a light diffusion film in which a projection condensing layer having a constant width on the surface of the film is formed. Further, JP-A-6-34761
No. 3 discloses a light diffusing film having a large number of lenses disposed on the surface.

However, each of the film-shaped light diffusing materials described in the above-mentioned publications has a problem that although the light emitting surface luminance is high, the light diffusing property is inferior and the viewing angle of the liquid crystal panel is narrowed. Further, there is a problem that the manufacturing process is complicated and cannot be easily manufactured.

[0006]

Accordingly, an object of the present invention is to provide silica composite resin particles which are excellent in light diffusivity and light transmissivity and do not lower the surface emission luminance of the light diffusable material, and a method for producing the same. That is. The silica composite resin particles can be used for purposes other than light diffusion.

Another object of the present invention is to provide a light diffusing resin composition which is excellent in light diffusing property and light transmitting property and can easily obtain a light diffusing material having high surface emission luminance. Still another object of the present invention is to provide a light diffusion sheet which is excellent in light diffusion and light transmission, has high surface emission luminance, and is easy to manufacture.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, the composite resin particles having fine silica particles dispersed therein have improved light diffusivity, The inventors have found that the use of a light-diffusing material or the like increases surface emission luminance, and have reached the present invention. That is, the silica composite resin particles of the present invention are particles obtained by dispersing silica fine particles having an average particle diameter of 500 nm or less in a transparent or translucent matrix resin.

The method for producing silica composite resin particles of the present invention is a method for producing the above silica composite resin particles,
In this method, after adding silica fine particles to the polymerizable monomer, the polymerizable monomer is subjected to aqueous suspension polymerization in the presence of the silica fine particles. The light diffusing resin composition of the present invention is a resin composition obtained by dispersing the light diffusing agent comprising the silica composite resin particles in a transparent or translucent resin.

The first light diffusing sheet of the present invention is obtained by molding the above light diffusing resin composition into a sheet. The second light diffusing sheet of the present invention is obtained by binding the light diffusing agent composed of the silica composite resin particles to the surface of a transparent or translucent sheet-shaped transparent base material using a binder resin.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

[Silica Composite Resin Particles and Production Method Thereof] The silica composite resin particles of the present invention contain silica fine particles and a matrix resin, and the silica fine particles are dispersed in the matrix resin. Silica fine particles used for silica composite resin particles,
Since it is of a fine size having an average particle diameter of 500 nm or less, it is possible to efficiently refract light that has collided with the silica fine particles in the silica composite resin particles, and to preferentially diffuse the light in the transmission direction. As well as excellent light transmittance, it is possible to realize that the surface emission luminance is not reduced.

The average particle diameter of the silica fine particles is not particularly limited as long as it is 500 nm or less, and is preferably 200 nm or less. When the average particle diameter of the silica fine particles exceeds 500 nm, light colliding with the silica fine particles is easily absorbed, and cannot be preferentially diffused in the transmission direction. In addition, as a method of measuring the average particle diameter of the silica fine particles, for example, a method of measuring the average particle diameter using a submicron particle diameter analyzer or an average particle diameter based on a photograph taken with a transmission electron microscope Examples of the method include a method of measuring, and a method of dispersing in a solvent and measuring an average particle diameter using scattering of laser light or the like.

The shape of the silica fine particles is not particularly limited, but is preferably a lump, a spheroid, or a sphere, because it hardly exhibits anisotropy of dispersion inside the silica composite resin particles. The silica fine particles include silica, and are not particularly limited as long as the particles are within the above average particle diameter range.If the silica fine particles are, for example, organic polymer composite silica fine particles having an organic polymer fixed on the surface, This is preferable because the dispersibility of the silica fine particles in the silica composite resin particles is improved, and light can be more efficiently refracted and preferentially diffused in the transmission direction to improve surface emission luminance.

The organic polymer composite silica fine particles have a three-dimensional network structure mainly composed of silica particles, and silicon is mainly bonded to oxygen atoms.
In addition, metal atoms other than silicon, organic groups, and hydroxyl groups were contained in the silica particle main body, or various groups derived from the raw material compounds used in producing the organic polymer composite silica fine particles remained or were fixed on the surface. The organic polymer may partially include an organic polymer. The organic group is at least one selected from the group consisting of an alkyl group having 20 or less carbon atoms which may be substituted, a cycloalkyl group, an aryl group, and an aralkyl group.

The organic polymer in the organic polymer composite silica fine particles is preferable because the organic polymer composite silica fine particles can be sufficiently dispersed in the polymerizable monomer in the method for producing silica composite resin particles described below. Regarding the molecular weight, shape, composition, presence or absence of functional groups, etc. of the organic polymer,
There is no particular limitation, and any organic polymer can be used. Regarding the shape of the organic polymer, any shape such as a linear, branched, or crosslinked structure can be used. The molecular weight of the organic polymer is not particularly limited, and preferably has a number average molecular weight of 200,000 or less, more preferably 50,000 or less. If the molecular weight is too high, it may not be dissolved in the polymerizable monomer, which is not preferable.

Examples of the organic polymer include (meth) acrylic resin, polyolefin such as polystyrene, polyvinyl acetate, polyethylene and polypropylene, polyester such as polyvinyl chloride, polyvinylidene chloride and polyethylene terephthalate, and copolymers thereof. And a resin partially modified with a functional group such as an amino group, an epoxy group, a hydroxyl group, and a carboxyl group.

As the organic polymer, any organic polymer can be used as described above, and it is particularly preferable that the organic polymer has a structure derived from the organic polymer (P) described later.
The organic polymer composite silica fine particles used in the present invention are composite fine particles in which an organic polymer is fixed on the surface of a silica particle main body, but the term “fixing” as used herein does not mean mere adhesion and adhesion, but refers to organic polymer. This means that the organic polymer is not detected in the washing liquid obtained by washing the composite silica fine particles with an arbitrary solvent, which strongly suggests that the organic polymer is chemically bonded to the silica particle body. I have.

The average particle size of the organic polymer composite silica fine particles is preferably 5 to 200 nm, more preferably 5 to 200 nm.
１００100 nm. When the average particle diameter is less than 5 nm, the surface energy of the organic polymer composite silica fine particles is increased, and aggregation and the like are easily caused. On the other hand, if the average particle size exceeds 200 nm, the light diffusivity may decrease.

The coefficient of variation of the particle diameter of the organic polymer composite silica fine particles is preferably 50% or less, more preferably 30% or less. If the coefficient of variation of the particle size exceeds 50%, the particle size distribution of the organic polymer composite silica fine particles is widened, and the light diffusivity is undesirably reduced. When the alkoxy group is contained in the organic polymer composite silica fine particles, the organic polymer composite silica fine particles can be sufficiently dispersed in the polymerizable monomer in the method for producing silica composite resin particles described below. Therefore, it is preferable. The content of the alkoxy group is preferably 0.01 to 50 mmol per 1 g of the organic polymer composite silica fine particles.
It is.

It is preferable that the content of silica in the organic polymer composite silica fine particles be 20% by weight or more based on the whole organic polymer composite silica fine particles, because the light diffusibility is improved. Further, when the content is 95% by weight or less, it is preferable because the organic polymer composite silica fine particles can be sufficiently dispersed in the polymerizable monomer in the method for producing silica composite resin particles described below.

As a method for producing the organic polymer composite silica fine particles, for example, at least one particle per molecule is used.
And at least one Si-OR ¹ group (R ¹ is at least one group selected from a hydrogen atom, an alkyl group and an acyl group, alkyl and acyl groups a group which may be substituted;. when R ¹ are a plurality in one molecule, an organic polymer (P) containing a plurality of R ¹ is which may be different from each other), either alone or hydrolytic There is a method of performing hydrolysis and condensation together with a decomposable silicon compound.

As the organic polymer (P), for example,
After co-hydrolyzing / condensing a silane coupling agent having a double bond group or a mercapto group and a hydrolyzable silicon compound and / or a derivative thereof, in the presence of the obtained co-hydrolysis / condensate, It is produced by a method of radically (co) polymerizing a radically polymerizable monomer. Examples of hydrolyzable silicon compounds include, for example, methyltriacetoxysilane, dimethyldiacetoxysilane, trimethylacetoxysilane, tetraacetoxysilane, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, methyltrimethoxy Examples include silane, phenyltrimethoxysilane, dimethoxymethylphenylsilane, dimethoxydimethylsilane, trimethoxymethylsilane, trimethylethoxysilane, dimethyldiethoxysilane, dimethoxydiethoxysilane, and the like, and two or more kinds may be used in combination.

The method of hydrolysis / condensation is not particularly limited, but is preferably performed in a solution since the hydrolysis / condensation reaction can be easily performed. In the hydrolysis / condensation reaction, an acidic catalyst or a basic catalyst may be used, or two or more catalysts may be used in combination. The matrix resin used for the silica composite resin particles is not particularly limited as long as it is a transparent or translucent resin, but if it is a transparent resin, it has excellent light transmittance and can improve surface emission luminance. preferable. On the other hand, if neither transparent nor translucent, the silica composite resin particles absorb light, and it becomes impossible to obtain excellent light diffusion.

Examples of the matrix resin include vinyl chloride resins such as vinyl chloride polymer and vinyl chloride-vinylidene chloride copolymer; vinyl ester resins such as vinyl acetate polymer and vinyl acetate-ethylene copolymer; (Meth) acrylic ester resins such as (meth) acrylic acid ester (co) polymer, (meth) acrylic acid ester-acrylonitrile copolymer, (meth) acrylic acid ester-styrene copolymer; styrene polymer, styrene Styrene resins such as acrylonitrile copolymer, styrene-butadiene-acrylonitrile copolymer, styrene-butadiene block copolymer, styrene-isoprene block copolymer; poly (ε-caprolactam), adipic acid and hexamethylenediamine; Resin such as condensate of terephthalate Polyester resins such as condensates of ethylene glycol and ethylene glycol, condensates of adipic acid and ethylene glycol; polyolefin resins such as polyethylene, polypropylene, chlorinated polyethylene, chlorinated polypropylene, carboxyl-modified polyethylene, polyisobutylene, and polybutadiene; cellulose acetate,
Cellulose derivatives such as cellulose propionate and nitrocellulose; phenolic resins such as butyral resin, novolak resin and resol resin; amino resins such as urea resin, melamine resin and benzoguanamine resin; various alkyd resins, urethane modified resins and polyamine resins Resins, epoxy resins, cyclized rubbers and the like, and one kind alone,
Alternatively, two or more kinds may be used in combination. When silica composite resin particles are used as a light diffusing agent, the matrix resin is appropriately selected depending on the type of a transparent resin described below.

Further, it is preferable that the matrix resin is a resin having a crosslinked structure, since the solvent resistance and the heat resistance are improved and the deterioration and the like are suppressed. When it does not have a crosslinked structure,
This is because, at the time of molding the light diffusing resin composition described later, the silica composite resin particles themselves used as the light diffusing agent may be melted, and the silica fine particles inside the silica composite resin particles may be easily oriented.

The ratio of the silica fine particles contained in the whole silica composite resin particles is based on the whole silica composite resin particles.
Usually, it is in the range of 0.1 to 70% by weight, preferably 0.5 to 50% by weight, more preferably 1 to 30% by weight. If the ratio of the silica fine particles is less than 0.1% by weight, the light colliding with the silica fine particles cannot be efficiently refracted, and cannot be preferentially diffused in the transmission direction. In the light diffusing material using the silica composite resin particles, the light transmittance is reduced and the surface emission luminance is also reduced. On the other hand, if it exceeds 70% by weight, the shape of the silica composite resin particles tends to be deformed, which is unfavorable, such as exhibiting anisotropy and easily causing poor dispersion.

The silica composite resin particles of the present invention may contain, if necessary, other additives in addition to the silica fine particles and the matrix resin, for example, phosphors such as inorganic phosphors and organic phosphors; dyes such as fluorescent dyes; Pigment; Colorant; Stabilizer; Dispersant; Flame Retardant; Glass; Glass Fiber; Metal Fiber; Anti-Aging Agent;

The shape of the silica composite resin particles of the present invention is not particularly limited, but is preferably spherical or spheroidal, more preferably spherical. The reason that spherical or spheroidal particles are preferably used is that, when a light diffusing agent composed of silica composite resin particles is added to a transparent resin, it becomes difficult to show anisotropy, the dispersibility becomes good, and the appearance is improved. This is because the mechanical strength can be further improved.

The average particle diameter of the silica composite resin particles of the present invention depends on the particle diameter of the contained silica fine particles, but is usually 0.1 to 500 μm, preferably 0.5 to 1 μm.
00 μm, more preferably 1 to 50 μm. In addition,
The particle diameter of the silica composite resin particles can be measured by a conventionally known method such as a laser scattering method, a Coulter counter method, and a centrifugal sedimentation method.

The silica composite resin particles of the present invention are particularly excellent as a light diffusing agent. Examples thereof include a blocking agent for a resin film, an additive for a toner for developing an electrostatic image, an additive for a decorative board, and a filler for cosmetics. It can also be used for applications. Examples of the method for producing the silica composite resin particles include, for example, emulsion polymerization in which a polymerizable monomer composition obtained by adding silica fine particles to a polymerizable monomer is dispersed or emulsified in a medium to perform polymerization, suspension polymerization, or There is a method of forming silica composite resin particles by dispersion polymerization in which a polymerizable monomer composition is dissolved in a solution and precipitated by polymerization. The shape of the silica composite resin particles obtained by the above polymerization method is spherical, and because the standard deviation of the particle diameter is small,
As described above, when a light diffusing agent composed of silica composite resin particles is added to a transparent resin, it becomes difficult to exhibit anisotropy, the dispersibility is improved, and the appearance and mechanical strength are further improved. This is because

Among the above-mentioned production methods, silica fine particles are added to the polymerizable monomer because the compounding is simple, the silica fine particles can be easily dispersed, and spherical particles can be easily obtained. Thereafter, a method in which the polymerizable monomer is subjected to aqueous suspension polymerization in the presence of the silica fine particles is preferable. The silica fine particles may be surface-treated by various methods for the purpose of improving dispersibility in the polymerizable monomer composition. Examples of the surface treatment include a method of treating with a long-chain hydrocarbon such as stearic acid and oleic acid; a method of treating with a polymerizable monomer having a polar group such as acrylic acid and methacrylic acid; A method of treating with a polyhydric alcohol; a method of treating with an amine such as triethanolamine; a method of treating with various coupling agents; a functional group on the surface of the silica fine particles and an aziridine group or oxazolene which can react with the functional group on the surface. Reacting a polymer having a reactive group such as a group, an N-hydroxyacrylamide group, an epoxy group, a thioepoxy group, an isocyanate group, a vinyl group, a silicon-based hydrolyzable group, or an amino group at a temperature of 20 to 350 ° C. Reacts the functional group on the surface of the silica fine particles with the polymer, and grafts the polymer onto the surface of the silica fine particles. And the like can be given. However, in order to further improve the dispersibility in the polymerizable monomer composition, it is preferable that the silica fine particles are the above-mentioned organic polymer composite silica fine particles, rather than the surface-treated silica fine particles.

Examples of the polymerizable monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenyl Styrene, o-chlorostyrene, m-chlorostyrene, p
Styrene monomers such as chlorostyrene; acrylic acid;
Methyl acrylate, ethyl acrylate, acrylic acid n-
Butyl, isobutyl acrylate, dodecyl acrylate,
Stearyl acrylate, 2-ethylhexyl acrylate, tetrahydrofurfuryl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate (Meth) acrylic monomers such as 2-ethylhexyl methacrylate, stearyl methacrylate, ethylene, propylene, butylene, vinyl chloride, vinyl acetate, acrylonitrile, acrylamide, methacrylamide, N-vinylpyrrolidone and the like. Species alone,
Alternatively, two or more kinds may be used in combination.

In the suspension polymerization method, a dispersion stabilizer can be added to stabilize suspended particles. Examples of the dispersion stabilizer include water-soluble polymers such as polyvinyl alcohol, gelatin, tragacanth, starch, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, sodium polyacrylate, and sodium polymethacrylate, anionic surfactants, and cationic surfactants. There are surfactants, zwitterionic surfactants, nonionic surfactants, etc., as well as alginate, zein, casein, barium sulfate, calcium sulfate, barium carbonate, magnesium carbonate, calcium phosphate, talc, clay, diatomaceous earth, bentonite , Titanium hydroxide,
Thorium hydroxide, metal oxide powder and the like are used. Examples of the anionic surfactant include fatty acid oils such as sodium oleate and castor oil, and alkyl sulfate salts such as sodium lauryl sulfate and ammonium lauryl sulfate;
Alkyl benzene sulfonates such as sodium dodecyl benzene sulfonate; alkylene naphthalene sulfonate, alkane sulfonate, dialkyl sulfosuccinate, alkyl phosphate ester salt, naphthalene sulfonate formalin condensate, polyoxyethylene alkyl phenyl ether sulfate And polyoxyethylene alkyl sulfate salts. As a nonionic surfactant, polyoxyethylene alkyl alkyl ether,
Polyoxyethylene alkylphenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxysorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin fatty acid ester,
Oxyethylene-oxypropylene block polymer and the like. 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 amphoteric surfactant include lauryl dimethylamine oxide. These dispersion stabilizers can be appropriately used usually within a range of 0.01 to 20% by weight based on the polymerizable monomer composition.

[0034] The solvent used in the suspension polymerization method is not particularly limited as long as it does not completely dissolve the polymerizable monomer, but an aqueous medium is preferably used. These solvents are usually used in an amount of 20 to 10 based on the polymerizable monomer composition.
It can be used appropriately within the range of 000% by weight. Further, as the polymerization initiator used in the suspension polymerization method, generally known free radical catalysts such as benzoyl peroxide, lauroyl peroxide, tertiary butyl hydroxy peroxide, cumene peroxide, methyl ethyl ketone peroxide, Organic peroxides such as tert-butyl perphthalate and caproyl peroxide; inorganic oxides such as potassium persulfate, sodium persulfate and hydrogen peroxide; azobisisobutyronitrile, azobisisobutylamide, 2,2'- (2,4-
Dimethylvaleronitrile), azobis (α-methylvaleronitrile), azobis (α-methylbutyronitrile)
And the like, and one kind may be used alone or two or more kinds may be used in combination. These polymerization initiators can be appropriately used usually in the range of 0.01 to 20% by weight based on the polymerizable monomer composition.

The control of the particle size and the polymerization are preferably performed in a nitrogen atmosphere. The ratio of the silica fine particles and the silica fine particles to the polymerizable monomer mixed at the time of suspension polymerization [100 × (silica fine particles) / (polymerizable monomer + silica fine particles)] is usually 0.1
It is in the range of from 70 to 70% by weight, preferably from 0.5 to 50% by weight, more preferably from 1 to 30% by weight. If the ratio of the silica fine particles is less than 0.1% by weight, the light colliding with the silica fine particles cannot be efficiently refracted, and cannot be preferentially diffused in the transmission direction. Also,
In the light diffusing material using the silica composite resin particles, the light transmittance is reduced and the surface emission luminance is also reduced. On the other hand,
If the content exceeds 70% by weight, the shape of the silica composite resin particles is likely to be deformed, resulting in anisotropy and poor dispersion.

The conditions of the suspension polymerization, that is, the polymerization temperature, time, stirring device and the like are not particularly limited, and the conditions of the conventionally known suspension polymerization method can be appropriately selected and carried out. Further, as described above, the silica composite resin particles preferably have a crosslinked structure. The method for producing the silica composite resin particles having a crosslinked structure is not particularly limited. For example, in the above suspension polymerization method, a plurality of polymerizable double bond groups may be added to the polymerizable monomer composition in the molecule. And a method of polymerizing a polymerizable monomer composition to which a crosslinker having a single polymer is added. Examples of such a crosslinking agent include trimethylolpropane triacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, decaethylene glycol dimethacrylate, pentadecaethylene glycol dimethacrylate, Pentacontahector ethylene glycol dimethacrylate,
Aromatic divinyl compounds such as 1,3-butylene dimethacrylate, allyl methacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, diethylene glycol dimethacrylate phthalate; divinylbenzene, divinylnaphthalene and derivatives thereof; N , N-divinylaniline, divinyl ether,
Crosslinking agents such as divinyl sulfide and divinyl sulfonic acid, as well as polybutadiene, polyisoprene, unsaturated polystyrene, and JP-B-57-56507, JP-A-59-221304, and JP-A-59-2
No. 21305, JP-A-59-221306,
Reactive polymers described in JP-A-59-221307 and the like may be used. When the addition ratio of these crosslinking agents is adjusted to 5% by weight or more, more preferably 10% by weight or more, based on the entire polymerizable monomer, the obtained silica composite resin particles have thermomechanical properties. It is particularly preferable for improvement.

Further, in the case of producing silica composite resin particles by a suspension polymerization method, at the time of polymerization, a pigment, a colorant ( Dyes), plasticizers, polymerization stabilizers, magnetic powders, ultraviolet absorbers, antistatic agents, flame retardants, and other additives can be blended or added in appropriate amounts. The method for producing the silica composite resin particles is, in addition to the polymerization method such as the suspension polymerization method, kneading and pulverizing the above-described matrix resin and silica fine particles,
There is a method of granulating by a conventionally known method such as a method of granulating. [Light-diffusing resin composition] The light-diffusing resin composition of the present invention comprises a light-diffusing agent comprising silica composite resin particles described in detail above, and a transparent or translucent resin (hereinafter, transparent to translucent resin). Is sometimes referred to as a transparent resin.), And a light-diffusing material having excellent light-diffusing properties and light-transmitting properties and having high surface emission luminance can be easily obtained.

The transparent resin is not particularly limited as long as it is transparent or translucent. For example, vinyl chloride resins such as vinyl chloride polymer and vinyl chloride-vinylidene chloride copolymer; vinyl acetate polymer; Vinyl acetate resins such as vinyl acetate-ethylene copolymers; styrene polymers, styrene-acrylonitrile copolymers, styrene-butadiene-acrylonitrile copolymers, styrene-butadiene block copolymers, styrene-isoprene block copolymers, Styrene resins such as styrene-methyl methacrylate copolymer; polycarbonate resins, (meth) acrylic resins, (meth) acrylate (co) polymers,
(Meth) acrylate resins such as (meth) acrylate-acrylonitrile copolymer, (meth) acrylate-styrene copolymer; condensates of terephthalic acid and ethylene glycol, adipic acid and ethylene glycol Polyester resins such as condensates of the above; transparent or translucent resins such as polyethylene, polypropylene, chlorinated polyethylene, chlorinated polypropylene, carboxyl-modified polyethylene, polyisobutylene, and polyolefin resins such as polybutadiene;
Alternatively, two or more kinds may be used in combination.

The optimum range of the mixing ratio of the light diffusing agent to the entire light diffusing resin composition varies depending on the intended use, but is preferably 3 to 90% by weight, more preferably 5 to 90% by weight.
80% by weight, most preferably 10-70% by weight.
If the blending ratio of the light diffusing agent is less than 3% by weight, sufficient light diffusing properties cannot be obtained in a light diffusing material such as a light diffusing sheet obtained from the light diffusing resin composition, and the surface emission luminance is reduced. May drop. On the other hand, if it exceeds 90% by weight, sufficient light transmittance cannot be obtained, and the surface emission luminance may be reduced.

The method for producing the light diffusing resin composition includes:
For example, it can be obtained by dispersing a light diffusing agent composed of the silica composite resin particles in a transparent resin.
The method for obtaining the light-diffusing resin composition is not particularly limited. For example, for a transparent resin, a light-diffusing agent composed of silica composite resin particles, and, if necessary,
By blending an appropriate amount of an organic solvent such as toluene and forming a coating by stirring and mixing, a light diffusing resin composition can be easily obtained, and a transparent resin in which a light diffusing agent comprising silica composite resin particles is melted. A conventionally known dispersion method such as a kneading method can be applied. [Light-diffusing sheet] The first light-diffusing sheet of the present invention is formed by molding the light-diffusing resin composition described in detail above into a sheet.

The second light diffusing sheet of the present invention is a transparent or translucent sheet substrate (hereinafter, the transparent or translucent sheet substrate is sometimes referred to as a transparent sheet substrate).
The light diffusing agent composed of the silica composite resin particles described in detail above is bound to the surface using a binder resin. As the first light diffusion sheet, for example, a light diffusion sheet 1 shown in FIG. 1 is cited, and silica composite resin particles 2 are dispersed in a transparent resin 3. The thickness of the light diffusion sheet is not particularly limited, but is usually 1 to 10,000.
μm, preferably 10 to 5000 μm.

The first light diffusing sheet is obtained by molding the light diffusing resin composition by extrusion molding, injection molding or the like. As the second light diffusing sheet, for example, a light diffusing sheet 4 shown in FIG. 2 is cited, and a light diffusing agent composed of silica composite resin particles 2 using a binder resin 6 on the surface of a transparent sheet-like base material 5 Are bound. The thickness of the light diffusion sheet is the same as the thickness of the first light diffusion sheet.

The material of the transparent sheet substrate is not particularly limited as long as it is transparent or translucent. Examples of the material of the transparent sheet substrate include various kinds of glass, polyolefin resin, polyester resin, and the like. Examples include sheets and films of acrylic resin, vinyl chloride resin, polycarbonate resin and the like. As the binder resin, for example, polyester resin, styrene resin,
Acrylic resin, melamine resin, silicone resin,
Examples thereof include urethane-based resins, epoxy-based resins, and vinyl acetate-based resins. One type may be used alone, or two or more types may be used in combination.

The mixing ratio of the silica composite resin particles and the binder resin can be appropriately selected depending on the use of the light diffusion sheet to be obtained and the kind of the binder resin, but preferably 100% by weight of the total of the silica composite resin particles and the binder resin. 3 to 90% by weight of the silica composite resin particles and 97 to 10% by weight of the binder resin, more preferably 5 to 80% by weight of the silica composite resin particles and the binder resin 95
-20% by weight. When the amount of the silica composite resin particles is less than 3% by weight, sufficient light diffusivity cannot be obtained, and the surface emission luminance may be reduced. On the other hand, silica composite resin particles
When the content is more than 10% by weight, the strength of the light diffusion sheet is reduced, and sufficient light transmittance is not obtained, so that the surface emission luminance may be reduced.

The second light diffusing sheet is obtained by applying a binder composition containing silica composite resin particles containing a binder resin and silica composite resin particles to a transparent base material using a molding machine or a film forming machine, and drying. Obtained by In addition,
When the transparent resin in the light diffusing resin composition is a binder resin, the light diffusing resin composition can be used as it is as a silica composite resin particle-containing binder composition.

Since each of the above light diffusion sheets contains a light diffusion agent composed of silica composite resin particles, the light diffusion sheet is excellent in light diffusion and light transmission, and has high surface emission luminance. In addition, since it is formed into a sheet or the silica composite resin particles are bound with a binder, it is easily manufactured.

[0047]

Hereinafter, specific examples of the present invention will be described.
The present invention is not limited to the following examples. First,
In the production examples, polymerizable polysiloxane, organic polymer and organic polymer composite silica fine particles were produced. The number average molecular weight of the polymerizable polysiloxane and the organic polymer obtained in the following production examples, the average particle diameter of the organic polymer composite silica fine particles, and the coefficient of variation of the particle diameter were measured by the following methods. (Number average molecular weight) Using a high-speed GPC device HLC-8020 (manufactured by Tosoh Corporation), polystyrene was measured as a standard substance. (Average particle diameter and coefficient of variation of particle diameter) Submicron particle diameter analyzer NICOMP MODEL 370
(Nozaki Sangyo Co., Ltd.).

(Production Example 1) (Production of Organic Polymer (P-1)) In a 300 ml four-necked flask equipped with a stirrer, a thermometer and a condenser, 144.5 g of tetramethoxysilane and γ-methacryloxypropyl tri 23.6 g of methoxysilane, 19 g of water, 30 g of methanol and 5 g of Amberlyst 15 (a cation exchange resin manufactured by Rohm and Haas Japan) were stirred and reacted at 65 ° C. for 2 hours. After the reaction mixture was cooled to room temperature, a distillation column was provided in place of the cooling tube, a cooling tube connected to the distillation column and an outlet were provided, and the temperature was raised to 80 ° C. over 2 hours under normal pressure until the outflow of methanol was stopped. The same temperature was maintained to further advance the reaction. again,
After cooling to room temperature, Amberlyst 15 was separated by filtration to obtain a polymerizable polysiloxane having a number average molecular weight of 1,800.

Next, 200 g of toluene as an organic solvent was put into a 1-liter flask equipped with a stirrer, a dropping port, a thermometer, a cooling tube and a nitrogen gas inlet, nitrogen gas was introduced, and the inside temperature of the flask was reduced while stirring. Heated to 110 ° C. 20 g of the polymerizable polysiloxane obtained above,
80 g of methyl methacrylate, 10 g of 2-ethylhexyl acrylate, 60 g of styrene, 30 g of butyl acrylate and 2,2′-azobisisobutyronitrile 6
g was added dropwise over 2 hours from the dropping port.
After the addition, stirring was continued for 1 hour at the same temperature, and 0.4 g of 1,1′-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane was added twice every 30 minutes. The copolymerization was carried out by heating for 2 hours, and the number average molecular weight was 1
A solution in which 2,000 organic polymers (P-1) were dissolved in toluene was obtained. The solid content in the resulting solution is 49.5%
Met.

(Production Example 2) (Production of Organic Polymer Composite Silica Fine Particle Dispersion (1))
496 g of butyl acetate and 124 g of methanol were placed in a 1-liter four-necked flask equipped with a stirrer, two dropping ports (dropping ports A and B) and a thermometer.
The temperature was adjusted to 0 ° C. Then, while stirring the inside of the flask, a toluene solution 2 of the organic polymer (P-1) obtained in Production Example 1 was prepared.
A mixed solution (solution A) of 7 g and 72 g of tetramethoxysilane was added through a dropping port A through 28 g of water and 25% aqueous ammonia 9
g of methanol and 37 g of methanol (solution B) was added dropwise from the dropper b over 1 hour. After dropping, stirring was continued at the same temperature for 2 hours. Next, a mixed solution of 37 g of a toluene solution of the organic polymer (P-1) and 37 g of butyl acetate was dropped from the dropping port a over 1 hour. After dropping, at the same temperature
Stirring was continued for hours. Under a pressure of 110 mmHg, the temperature inside the flask was raised to 100 ° C., and ammonia, methanol, toluene, and butyl acetate were distilled off until the solid content concentration became 30%, and the organic polymer composite silica fine particles were dispersed in butyl acetate. Dispersion (1) was obtained. The average particle diameter of the obtained organic polymer composite silica fine particles was 27 nm, and the coefficient of variation of the particle diameter was 16%.

(Production Example 3) (Production of Organic Polymer Composite Silica Fine Particle Dispersion (2))
496 g of butyl acetate and 124 g of methanol were placed in a 1-liter four-necked flask equipped with a stirrer, two dropping ports (dropping ports A and B) and a thermometer.
The temperature was adjusted to 0 ° C. Then, a toluene solution 1 of the organic polymer (P-1) obtained in Production Example 1 was stirred while stirring the inside of the flask.
A mixed solution (solution A) of 0 g and 100 g of tetramethoxysilane (solution A) was dropped from a dropping port A over 1 hour from a dropping port of a mixed solution of 30 g of water, 30 g of 25% aqueous ammonia and 60 g of methanol (solution B). After dropping, stirring was continued at the same temperature for 2 hours. Next, a mixed solution of 37 g of a toluene solution of the organic polymer (P-1) and 37 g of butyl acetate was dropped from the dropping port a over 1 hour. After dropping, stirring was continued at the same temperature for 2 hours. Further, under a pressure of 110 mmHg, the temperature inside the flask was raised to 100 ° C., and ammonia,
Methanol, toluene and butyl acetate with solid content of 30
% To obtain a dispersion (2) in which organic polymer composite silica fine particles are dispersed in butyl acetate. The average particle diameter of the obtained organic polymer composite silica fine particles is 177 n.
m and the coefficient of variation of the particle diameter were 11%.

The particle diameter of the silica composite resin particles obtained in the following examples, the maximum particle diameter of the silica fine particles contained in the silica composite resin particles, the total light transmittance, the parallel ray transmittance, the haze and the brightness of the light diffusion sheet are as follows. Was measured by the following method. (Particle Diameter of Silica Composite Resin Particles) The measurement was performed using a Coulter Counter Multisizer II (manufactured by Coulter Corp.) under the condition of an aperture diameter of 100 μm. (Total light transmittance, parallel light transmittance and haze) Turbidity meter
Using NDH-1001 DP (manufactured by Nippon Denshoku Industries Co., Ltd.), the total light transmittance, parallel light transmittance and haze of the light diffusion sheet were measured. The total light transmittance was measured for evaluation of light transmittance. The parallel line transmittance and haze were measured for evaluation of light diffusivity. (Brightness) A light diffusion sheet is placed on the upper surface of a light guide plate type backlight device, and a brightness meter B-7 (TOPCON Co., Ltd.) is used.
Was used for the measurement.

Example 1 A flask equipped with a stirrer, an inert gas inlet tube, a reflux condenser and a thermometer was charged with polyvinyl alcohol (PVA-2).
05, manufactured by Kuraray Co., Ltd.), and 900 g of deionized water in which 0.5 g was dissolved was charged. Next, methyl methacrylate 80
g, trimethylolpropane trimethacrylate 14 g,
20 g of the organic polymer composite silica fine particle dispersion (1) obtained in Production Example 2 and 1 g of azobisisobutyronitrile
Was charged into a flask, and T.P. K. 3000 rpm with a homogenizer (manufactured by Tokushu Kika Kogyo Co., Ltd.)
The mixture was stirred at m for 5 minutes to form a uniform suspension.

Then, at 75 ° C. while blowing nitrogen gas.
After stirring at this temperature for 5 hours to carry out a polymerization reaction, the mixture is cooled, filtered, washed and dried with a suspension to obtain silica composite resin particles (1) having an average particle diameter of 10.5 μm. I got The average particle diameter of the silica fine particles in the silica composite resin particles (1) was 27 nm. Acrylic resin solution (Alloset 5247, manufactured by Nippon Shokubai, solid content 45
%) 100 parts by weight of silica composite resin particles (1)
36 parts by weight and 270 parts by weight of toluene were blended to form a paint. The obtained paint was applied on a polyester sheet using a bar coater and dried to obtain a light diffusion sheet (1) having a coating thickness of 15 μm. Table 1 shows the optical characteristics of the light diffusion sheet (1).

Example 2 In the same flask as in Example 1, 90 g of deionized water in which 0.5 g of polyoxyethylene alkyl sulfonammonium (Hytenol N-8, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was dissolved was added.
0 g was charged. Next, a mixture containing 75 g of styrene, 10 g of divinylbenzene, 50 g of the organic polymer composite silica fine particle dispersion (2) obtained in Production Example 3, and 1 g of lauroyl peroxide was charged into a flask.
K. 5 with a homogenizer (manufactured by Tokushu Kika Kogyo Co., Ltd.)
The mixture was stirred at 000 rpm for 5 minutes to form a uniform suspension.

Then, at 75 ° C. while blowing nitrogen gas.
After stirring at this temperature for 5 hours to carry out a polymerization reaction, cooling, filtration of the suspension, washing and drying are performed to obtain silica composite resin particles (2) having an average particle diameter of 7.3 μm. I got The average particle diameter of the silica fine particles in the silica composite resin particles (2) was 177 nm. Acrylic resin solution (Alloset 5247, manufactured by Nippon Shokubai, solid content 45
%) 100 parts by weight of silica composite resin particles (2)
36 parts by weight and 270 parts by weight of toluene were blended to form a paint. The obtained coating material was applied on a polyester sheet using a bar coater and dried to obtain a light diffusion sheet (2) having a coating film thickness of 12 μm. Table 1 shows the optical characteristics of the light diffusion sheet (2).

Comparative Example 1 In the same flask as in Example 1, deionized water 90 in which 0.5 g of polyoxyethylene alkyl sulfonammonium (Hytenol N-8, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was dissolved was added.
0 g was charged. Next, a mixture of 70 g of methyl methacrylate, 20 g of ethylene glycol dimethacrylate, 10 g of silica fine particles having an average particle diameter of 1.8 μm (Syloid 244, manufactured by Fuji Silysia Ltd.) and 1 g of azobisisobutyronitrile was placed in a flask. Preparation, T.
K. 3 with a homogenizer (manufactured by Tokushu Kika Kogyo Co., Ltd.)
The mixture was stirred at 000 rpm for 5 minutes to form a uniform suspension.

Then, at 75 ° C. while blowing nitrogen gas.
After stirring at this temperature for 5 hours to carry out a polymerization reaction, cooling, filtration of the suspension, washing and drying were performed to obtain comparative silica composite resin particles having an average particle diameter of 11.2 μm (1). ) Got. The average particle diameter of the silica fine particles in the comparative silica composite resin particles (1) was 1.8 μm. Acrylic resin solution (Alloset 5247, manufactured by Nippon Shokubai Co., Ltd.
36 parts by weight of the comparative silica composite resin particles (1) and 270 parts by weight of toluene were blended with 100 parts by weight (solid content: 45%) to form a paint. The obtained paint was applied on a polyester sheet using a bar coater and dried to obtain a comparative light diffusion sheet (1) having a coating thickness of 15 μm. Table 1 shows the optical characteristics of the comparative light diffusion sheet (1).

Comparative Example 2 Acrylic resin solution (Alloset 5247, manufactured by Nippon Shokubai Co., Ltd., solid content: 45%), 100 parts by weight, acrylic fine particles (Eposter MA1013, manufactured by Nippon Shokubai Co., Ltd.) Parts by weight and 270 parts by weight of toluene were blended to form a paint. By applying the obtained paint on a polyester sheet using a bar coater and drying,
A comparative light diffusion sheet (2) having a coating thickness of 15 μm was obtained. Table 1 shows the optical characteristics of the comparative light diffusion sheet (2).

Example 3 30 g of the silica composite resin particles (1) obtained in Example 1 and 70 g of a polymethyl methacrylate resin (Sumipec B, manufactured by Sumitomo Chemical Co., Ltd.) are kneaded at 200 ° C., and hot-pressed. Into a sheet having a thickness of 200 μm to obtain a light diffusion sheet (3). Table 1 shows the optical characteristics of the light diffusion sheet (3).

Example 4 Silica Composite Resin Particles (1) and Silica Composite Resin Particles (2)
The light diffusing sheet (4) was obtained in the same manner as in Example 3 except that the light diffusing sheet was changed to. Table 1 shows the optical characteristics of the light diffusion sheet (4). Comparative Example 3 A comparative light diffusing sheet (3) was obtained in the same manner as in Example 3, except that the silica composite resin particles (1) were changed to the comparative silica composite resin particles (1). Table 1 shows the optical characteristics of the comparative light diffusion sheet (3).

Comparative Example 4 A comparative light diffusing sheet (4) was prepared in the same manner as in Example 3 except that the silica composite resin particles (1) were changed to acrylic fine particles (Eposter MA1013, manufactured by Nippon Shokubai Co., Ltd.). ) Got. Table 1 shows the optical characteristics of this comparative light diffusion sheet (4).

[0063]

[Table 1]

[0064]

The silica composite resin particles of the present invention are excellent in light diffusivity and light transmissivity, and do not lower the surface emission luminance of the light diffusive material. The silica composite resin particles can be used for purposes other than light diffusion. The method for producing silica composite resin particles of the present invention can easily produce silica composite resin particles having the above-mentioned characteristics and being spherical and having a small standard deviation of the particle diameter.

The light diffusing resin composition of the present invention is excellent in light diffusing property and light transmitting property, and can easily obtain a light diffusing material having high surface emission luminance. The light diffusion sheet of the present invention is excellent in light diffusion and light transmission, has high surface emission luminance, and can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first light diffusion sheet of the present invention.

FIG. 2 is a sectional view showing a second light diffusion sheet of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 light diffusion sheet 2 silica composite resin particles (light diffusion agent) 3 transparent resin 4 light diffusion sheet 5 transparent sheet base material 6 binder resin

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08K 9/04 C08K 9/04 C08L 101/00 C08L 101/00 G02B 5/02 G02B 5/02 B

Claims (6)

[Claims] 1. Silica composite resin particles comprising fine silica particles having an average particle diameter of 500 nm or less dispersed in a transparent or translucent matrix resin. 2. The silica composite resin particles according to claim 1, wherein the silica fine particles are fine particles having an organic polymer fixed on the surface. 3. The method for producing silica composite resin particles according to claim 1, wherein the polymerizable monomer is added in the presence of the silica fine particles after adding the silica fine particles to the polymerizable monomer. A method for producing silica composite resin particles by subjecting water to aqueous suspension polymerization. 4. A light diffusing resin composition obtained by dispersing the light diffusing agent comprising the silica composite resin particles according to claim 1 in a transparent or translucent resin. 5. A light diffusing sheet formed by molding the light diffusing resin composition according to claim 4 into a sheet. 6. A transparent or translucent sheet-like substrate surface,
A light diffusion sheet formed by binding the light diffusion agent comprising the silica composite resin particles according to claim 1 or 2 using a binder resin.