JP2005126683A - Light diffusive particle-containing molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light diffusive particle-containing molded article which is excellent in light diffusivity, can lessen lowering of a total light transmission rate and has a high transmission efficiency of a diffused light. <P>SOLUTION: The light diffusive particle-containing molded article is obtained by blending light diffusive particles with a transparent base resin. Wherein the light diffusive particles are prepared from a polymer particle derived from a polymerizable vinyl monomer having a reflective index differed from that of the transparent base resin by 0.01-0.10, and its surface coated with a silica film. The silica film is composed of a composite particle constituted of a condensate of a polyalkoxysiloxane oligomer, and has the value of a diffused light transmission rate of ≥80% expressed by the formula: diffused light transmission rate (%)= total light transmission rate (%)×haze (%)×0.01. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light diffusing particle-containing molded article obtained by blending light diffusing particles with a transparent base resin, and more specifically, as the light diffusing particles, polymer particles derived from a polymerizable vinyl monomer and the heavy particles. The present invention relates to a light diffusing particle-containing molded article in which composite particles comprising a silica coating provided on the surface of the combined particles are used.

  Conventionally, in various molded products such as lighting equipment covers, lenses, light guide plates, video discs, projection TV screens and other optical parts, cosmetic containers, vending machine front plates, signboards, product displays, tabletop containers, etc. As the base material, various resins, in particular, thermoplastic resins such as polycarbonate resin, polystyrene resin, and acrylic resin are used.

  By the way, in various molded products, in order to increase the commercial value such as the design property, the light diffusibility is improved by blending light diffusing particles in the resin.

Conventionally, as this kind of light diffusing particles, inorganic particles such as glass, calcium carbonate, and silica, or resin particles made only of acrylic resin and styrene resin are used.
However, in the molded body using these light diffusing particles, there are problems that transparency is lowered and it is difficult to say sufficient in terms of improving light diffusibility.

To solve this problem, composite particles in which silica particles of 500 nm or less are dispersed in resin particles have been proposed (Patent Document 1 below).
However, according to such composite particles, although the light diffusibility is improved, there is a problem that the transmittance of the diffused light is lowered.
Japanese Patent Laid-Open No. 10-265580

  In view of the above-described conventional problems, the present invention can provide a light diffusing particle-containing molded article that is excellent in light diffusibility and has little reduction in total light transmittance and that has high transmission efficiency of diffused light. The issue is to provide.

As a result of intensive studies in view of the above problems, the present inventors have found that the above problems can be solved by the following means, and have solved the present invention.
That is, the present invention is a light diffusing particle-containing molded product obtained by blending light diffusing particles with a transparent base resin,
The light diffusing particles are polymer particles derived from a polymerizable vinyl monomer having a refractive index difference of 0.01 to 0.10 with respect to the transparent base resin, and a silica coating provided on the surface of the polymer particles. The silica coating is a composite particle comprising a polyalkoxysiloxane oligomer condensate,
(Formula) Diffuse light transmittance (%) = Total light transmittance (%) × Haze (%) × 0.01
The diffused light transmittance value represented by the formula (1) is 80% or more.
The light diffusing particle-containing molded product of the present invention is light diffusive compared to the case where resin particles such as inorganic particles, acrylic resin, and styrene resin are used because the light diffusing particles are predetermined composite particles. It can be excellent and the total light transmittance is hardly decreased, and the diffuse light transmittance can be 80% or more. Therefore, for example, in a liquid crystal display using the same, power loss can be suppressed because there is little loss of light from the backlight.
In the present specification, the term “transparent” includes translucent. Further, the light diffusing particles mean particles that improve the light diffusibility of the molded body by adding them to the resin as compared with the unmixed ones.

In the present invention, the silica coating is preferably provided so that the surface of the polymer particles is exposed with an aperture ratio of 0.1-1.
According to such a configuration, the familiarity between the composite particles and the transparent base resin can be improved, and more sufficient transparency can be maintained. Further, compared to the case of using composite particles in which the surface of the polymer particles is completely covered with a silica coating, complex light reflection and refraction occurs, and more excellent light diffusibility can be expressed.
If the aperture ratio of the silica coating is less than 0.1, there is a risk that the light diffusion and reflectivity will be relatively poor, and if the aperture ratio exceeds 1, the coating is liable to peel off, which is not preferable. . A more preferable aperture ratio is 0.1 to 0.8.
The composite particles having an opening ratio of 1 means that the silica coating covers almost half of the polymer particles. Moreover, an aperture ratio is measured by the method as described in an Example.

In addition, in the composite particles having such an aperture ratio, it is preferable that the height h of the silica coating and the diameter D of the composite particles have a relationship of 0.5 ≦ h / D <1.
When h / D is 1 or more, light diffusion and reflectance may be relatively poor, and when h / D is less than 0.5, it is not preferable because peeling of the film easily occurs. In addition, h / D is measured by the method as described in an Example.

Furthermore, in this invention, the compounding quantity of the said light diffusable particle is 0.1-0.1 with respect to 100 weight part of said transparent base resin (100 weight part of resin components except various additives, such as a ultraviolet absorber). What is 20 weight part is preferable.
Within such a range, it can be ensured that the light diffusibility is excellent, the total light transmittance is hardly lowered, and the diffuse light transmittance is 80% or more.

  As described above, the light diffusing particle-containing molded article of the present invention can be excellent in light diffusibility and less reduced in total light transmittance, and has the advantage of high transmission efficiency of diffused light. Have.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
As illustrated in FIG. 1, the light diffusing particle-containing molded article of the present invention is constituted by blending light diffusing particles 2 with a transparent base resin 1,
(Formula) Diffuse light transmittance (%) = Total light transmittance (%) × Haze (%) × 0.01
The value of the diffuse light transmittance represented by is set to 80% or more.

The light diffusing particles 2 are provided on the surface of the polymer particles 2a derived from a polymerizable vinyl monomer having a refractive index difference of 0.01 to 0.10 with respect to the transparent base resin 1 and the surface of the polymer particles 2a. The composite particle 2 composed of the obtained silica coating 2b is preferably spherical or substantially spherical.
The silica coating 2b is composed of a polyalkoxysiloxane oligomer condensate. Preferably, as shown in FIG. 2, the surface of the polymer particles 2a has an opening ratio of 0.1 to 1, preferably 0.1. It is provided so as to be exposed at an aperture ratio of 0.8 and has anisotropy.
With such a configuration, for example, the reflection and refraction of complex light is more complicated than non-anisotropic particles such as spherical particles of silica alone or spherical composite particles in which the surface of polymer particles is completely covered with silica. Occurs, and more excellent light diffusibility can be expressed.

The light diffusing particle-containing molded article of the present invention is usually obtained by a molding method such as extrusion molding or injection molding by mixing composite particles and a transparent base resin, melting and kneading them.
In the light diffusing particle-containing molded product of the present invention, the compounding ratio of the composite particles is usually 0.1 to 20 parts by weight, preferably 0.3 to 15 parts by weight, with respect to 100 parts by weight of the transparent base resin. More preferably, it is 1 to 15 parts by weight. If the blending ratio exceeds 30 parts by weight, it is not preferable because it becomes difficult to produce a molded body. On the other hand, when the amount is less than 0.1 parts by weight, it is difficult to adjust the diffuse light transmittance to 80% or more, which is not preferable.
In addition, the light diffusing particle-containing molded body having such a blending ratio can be obtained by mixing and molding the transparent base resin and the composite particles at such a ratio.

In the present invention, a thermoplastic resin is usually used as the transparent base resin, and examples of the thermoplastic resin include (meth) acrylic resins, (meth) acrylic acid alkyl-styrene copolymer resins, and polycarbonates. Examples thereof include resins, polyester resins, polyethylene resins, polypropylene resins, polystyrene resins, and the like.
Among these, when excellent transparency is required, (meth) acrylic resin, (meth) acrylic acid alkyl-styrene copolymer resin, polycarbonate resin, and polyester resin are preferable. These thermoplastic resins can be used alone or in combination of two or more.
As the transparent base resin, one having a refractive index difference with respect to the polymer particles of 0.01 to 0.1, preferably 0.02 to 0.1 is selected and used.
When the difference in refractive index is less than 0.01, sufficient haze cannot be obtained, and the diffused light transmittance is less than 80%, which is not preferable. On the other hand, when the difference in refractive index is greater than 0.1, the light diffusibility of the molded product becomes too high, and the total light transmittance is significantly reduced.
In addition, trace amounts of additives, such as a ultraviolet absorber, a heat stabilizer, a coloring agent, and a filler, may be added to the transparent base resin.

In the composite particles of the present invention, the ratio of the polymer particles to the silica coating is preferably 10 to 500 parts by weight, and more preferably 20 to 300 parts by weight with respect to 100 parts by weight of the polymer particles.
Such composite particles are prepared, for example, by preparing a monomer composition containing a polymerizable vinyl monomer and a polyalkoxysiloxane oligomer at a blending ratio as described above, and polymerizing the polymerizable vinyl monomer by suspension polymerization. It is obtained by condensing an alkoxysiloxane oligomer.

Examples of the polymerizable vinyl monomer include styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, p-ethyl styrene, 2,4-dimethyl styrene, pn-butyl styrene, p-tert. -Butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, n-methoxy styrene, p-phenyl styrene, p -Styrene such as chlorostyrene and 3,4-dichlorostyrene and derivatives thereof,
Ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, isobutylene,
Vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride,
Vinyl esters such as vinyl acetate, vinyl propionate and vinyl butyrate,

  Methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl 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,

Acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate,
In some cases, acrylic acid, methacrylic acid, maleic acid, and fumaric acid can also be used.

  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 -N-vinyl compounds such as vinyl pyrrolidone, 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 these, styrene or methacrylic acid derivatives that are inexpensive in terms of cost are preferable.
The polymer particles may or may not be crosslinked, but are preferably crosslinked when solvent resistance is required.
Examples of the monomer used for crosslinking include monomers having two or more functional groups such as a polymerizable vinyl monomer such as ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, and divinylbenzene.

  The polymer particles may contain, for example, various additives such as an ultraviolet absorber, a heat stabilizer, and a colorant as long as they are each less than 1 part by weight with respect to 100 parts by weight of the polymer particles. .

  The polyalkoxysiloxane oligomer is usually inert to a polymerizable vinyl monomer (meaning that it is not copolymerized), and examples of the polyalkoxysiloxane oligomer include the structural formulas shown below.

Examples thereof include oligomers such as polymethoxysiloxane, polyethoxysiloxane, polypropoxysiloxane, and polybutoxysiloxane. Among these, polymethoxysiloxane oligomers and polybutoxysiloxane oligomers which are poorly water-soluble and have good phase separation from the resin are preferable, and in particular, polymethoxysiloxane oligomers and polybutoxysiloxane oligomers having a weight average molecular weight of 300 to 3000 are preferable. preferable. When the weight average molecular weight is less than 300 or more than 3000, it is difficult to form a silica coating film.
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 in which n = 1 to 2 in the above molecular formula, the water solubility becomes strong during hydrolysis of the functional group (during condensation). It is difficult and difficult to exist stably. In addition, polyalkoxysiloxane oligomers in which n = 40 or more in the above molecular formula is not preferable because the condensability and compatibility with the polymerizable vinyl monomer are reduced.

  In the present invention, it is preferable that the polymerizable vinyl monomer is styrene or a methacrylic acid derivative and the alkoxysiloxane oligomer is a polymethoxysiloxane oligomer or a polybutoxysiloxane oligomer.

  In addition, hydrolyzable alkoxy metal compounds other than silicon-based compounds may be added to these polyalkoxysiloxane oligomer condensates for the purpose of adding functions such as ultraviolet absorption.

In the present invention, the size and shape of the composite particles are not particularly limited. However, when the molded body is used as a signboard, a container or the like, the particle diameter is preferably 3 to 50 μm. When the body is used in an optical component, particularly an optical component that requires precision such as high-definition image display in a liquid crystal display, a projection television, or the like, 3 to 30 μm is preferable.
If it is 3 to 50 μm, a more uniform diffused light and a high total light transmittance can be obtained. In a field where a high-definition image such as a display is required, particles smaller than 3 to 30 μm are preferred. This is because a fine image can be obtained.
The particle diameter of the composite particles is adjusted by adjusting the mixing conditions of the monomer composition and water, the addition amount of the suspension stability and the surfactant, the stirring conditions of the above stirrer, and the dispersion conditions in the production method described later. Can be adjusted.

  The light diffusing particle-containing molded product of the present invention may be blended with resin particles (particles of resin alone) or inorganic particles in addition to the composite particles as long as the effects of the present invention are not impaired. Good.

A preferable light diffusing particle-containing molded article of the present invention has the above-described configuration. Hereinafter, a preferable method for producing the light diffusing particle-containing molded article will be described in steps (1) to (3). .
(1) (Preparation of monomer composition)
First, in addition to a polymerizable vinyl monomer and a polyalkoxysiloxane oligomer, a polymerization initiator for polymerizing the polymerizable vinyl monomer and other components are blended to prepare a monomer composition.
Here, as the polymerizable vinyl monomer and the polyalkoxysiloxane oligomer, those described above can be used.
The blending amount of the polyalkoxysiloxane oligomer is appropriately adjusted so as to obtain a desired opening ratio and h / D, but the viewpoint that the opening ratio is 0.1 to 1 and 0.5 ≦ h / D <1 is likely to be obtained. Therefore, 10 to 500 parts by weight is preferable with respect to 100 parts by weight of the polymerizable vinyl monomer, and more preferably 20 to 300 parts by weight. When the amount is less than 10 parts by weight, it is difficult to cover the coating state with a predetermined opening ratio and h / D. When the amount is more than 500 parts by weight, the polymer particles are hardly exposed, which is not preferable.

As the polymerization initiator, for example, an oil-soluble peroxide polymerization initiator or azo polymerization initiator used for aqueous suspension polymerization can be used.
Specific examples include benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, orthochloroperoxybenzoic acid, orthomethoxybenzoic acid peroxide, methyl ethyl ketone peroxide, diisopropyl peroxydicarbonate, cumene hydroperoxide, cyclohexanone peroxide, t-butyl. Peroxide polymerization initiators such as hydroperoxide and 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′- Examples thereof include azo initiators such as azobis (4-cyanovaleric acid) and dimethyl-2,2′-azobisisobutyrate.

Among these, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), benzoyl peroxide, lauroyl peroxide have a high decomposition rate of the polymerization initiator, etc. This is preferable.
The addition amount of the polymerization initiator is preferably 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.

(2) (Production of composite particles)
Next, using the prepared monomer composition, for example, by performing aqueous suspension polymerization in an aqueous medium, the polymerizable vinyl monomer is polymerized, and further, polyalkoxysiloxane is condensed to form composite particles.
Specifically, first, as the aqueous medium, water or a mixed medium of water and a water-soluble solvent such as alcohol is used.
In order to stabilize the suspension polymerized particles, the amount of the aqueous medium used is usually preferably 100 to 1000 parts by weight with respect to 100 parts by weight of the total of the polymerizable vinyl monomer and the polyalkoxysiloxane oligomer. .

In order to suppress the generation of emulsified particles in the aqueous medium, water-soluble polymerization prohibition such as nitrites, sulfites, hydroquinones, ascorbic acids, water-soluble vitamin Bs, citric acid and polyphenols is prohibited. An agent may be added.
Furthermore, you may add a suspension stabilizer as needed. Examples of the suspension stabilizer include phosphates such as calcium phosphate, magnesium phosphate, aluminum phosphate and zinc phosphate, pyrophosphates such as calcium pyrophosphate, magnesium pyrophosphate, aluminum pyrophosphate and zinc pyrophosphate, calcium carbonate And dispersion stabilizers of poorly water-soluble inorganic compounds such as magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, and colloidal silica. Among these, tribasic calcium phosphate, magnesium pyrophosphate, calcium pyrophosphate, and colloidal silica obtained by the metathesis method are preferable because polymer particles 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 are used alone or in combination of two or more. In consideration of the particle diameter of the resulting polymer particles and the dispersion stability during polymerization, the selection and use amount of the suspension stabilizer is appropriately adjusted and used. 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 0.001 to 0.003 with respect to 100 parts by weight of the aqueous medium. 1 part by weight.

In this way, the monomer composition is added and dispersed in the aqueous medium to which various additives are added.
As a method for dispersing the monomer composition, for example, a method in which the monomer composition is directly added to an aqueous medium and dispersed in the aqueous medium as monomer droplets by stirring force of a propeller blade or the like, a high shear force composed of a rotor and a stator is used. It is possible to adopt a method of dispersing using a homomixer that is a disperser that uses the above, an ultrasonic disperser, or the like. In addition, as a preferable method for making the particle diameters substantially uniform, a high-pressure disperser or a MPG (microporous glass) porous film using collision force between monomer droplets such as a microfluidizer or nanomizer and a collision force against the machine wall A method such as press-fitting the monomer composition into an aqueous medium can also be employed.
In addition, the monomer composition in an aqueous medium becomes spherical normally as a monomer droplet by dispersion | distribution.

Furthermore, suspension polymerization is started by heating the aqueous medium in which the monomer composition is dispersed.
The aqueous medium is preferably stirred during the polymerization reaction. For example, the stirring may be performed loosely enough to prevent the monomer droplets from floating and the particles after polymerization from being settled. In 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.

After the polymerization, the polyalkoxysiloxane oligomer is condensed.
Examples of the condensation method of the polyalkoxysiloxane oligomer include dehydration condensation using an acid catalyst or a base catalyst. Examples of the acid catalyst and base catalyst include inorganic acids such as hydrochloric acid, sulfuric acid and nitric acid, organic acids such as citric acid, ascorbic acid, isoascorbic acid and phenolic compounds, inorganic acids such as ammonia, sodium hydroxide, potassium hydroxide and ammonium nitrate. Bases and organic bases such as amine compounds and amide compounds can be used. When the production container is made of steel or stainless steel, it is preferable to use basic sodium hydroxide, ammonia or the like from the viewpoint of corrosion or 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, if necessary, the suspension stabilizer is decomposed with hydrochloric acid or the like, and the silica-coated polymer particles are separated as a hydrous cake by a method such as suction filtration, centrifugal dehydration, centrifugal separation, or pressure dehydration. The obtained water-containing cake is washed with water and dried to obtain the desired composite particles.

  According to the method for producing composite particles, since the method is not a method of applying silica particles to polymer particles by applying a high shear force, a polymer having no Tg (glass transition point) lower than 80 ° C. Even these particles can be easily coated. Examples of the polymer having a Tg lower than 80 ° C. include polyethyl acrylate, poly (n-butyl acrylate), poly (isobutyl acrylate), poly (lauryl acrylate), poly (stearyl acrylate), poly (2-ethylhexyl acrylate), and poly (methacrylic acid). Examples include ethyl, poly (n-butyl methacrylate), poly (isobutyl methacrylate), poly (lauryl methacrylate), poly (stearyl methacrylate), and poly (2-ethylhexyl methacrylate).

(3) (Production of light diffusing particle-containing molded product by molding)
Finally, the obtained composite particles and the base transparent resin are mixed, melt-kneaded, and molded into a predetermined shape by a molding method such as extrusion molding or injection molding to obtain a light diffusing particle-containing molded body.

In the diffusible particle-containing molded article of the present invention, the measurement of total light transmittance, haze, and the like were performed by the following methods.

(Measurement of total light transmittance, haze, diffuse light transmittance)
The total light transmittance and haze of the molded product were measured with a haze meter (based on “NDH-2000” JIS K7105 manufactured by Nippon Denshoku Co., Ltd.).
The diffuse light transmittance is the ratio of diffuse light to the total light transmittance. The diffuse light transmittance is defined as diffuse light transmittance (%) = total light transmittance (%) × haze (%) × 0.01
It calculated | required by the formula shown by.

(Measurement of particle diameter)
The particle diameter was measured by the Coulter counter method.
The Coulter counter method is a method of measuring the particle diameter by an electric resistance method called the Coulter principle.
In detail, this method is described in detail by placing an electrode on both sides of the aperture (pore) of the aperture tube in the electrolyte, passing an electric current, suspending the particles to be measured in the electrolyte, and using a manometer from inside the aperture tube. When the electrolyte is sucked and passes through the aperture, the electrolyte corresponding to the particle volume is replaced, and resistance is generated between both electrodes, but this resistance change is proportional to the volume of the particle passing through the aperture. This is a method of detecting and calculating this to obtain the volume average particle diameter of the particle diameter.
Specifically, according to REFERENCE MANUAL FOR THE COULTER MULTISIZER (1987) published by Coulter Electoronics Limited, calibration was performed using an aperture having a diameter of 100 μm. More specifically, as a particle diameter measuring device, a device composed of Coulter Multisizer II and Sampling Stand IIA (manufactured by Beckman Coulter) was used, and 0.1 g of particles in 10 ml of 0.1% nonionic surfactant solution. Pre-dispersed using a touch mixer and ultrasonic waves, and added to a beaker containing 300 ml of ISOTON II (manufactured by Beckman Coulter, Inc .: electrolyte for measurement) attached to the sampling stand II with a dropper while gently stirring. Then, the concentration meter on the main body screen was prepared to be around 10%, and the volume average particle diameter of 100,000 particles was measured.

(Refractive index measurement method)
1. Method for measuring refractive index of polymer particles 0.001 g of polymer particles are placed on a slide glass, and a liquid organic compound having a refractive index arbitrarily selected from the publication “Atago Refractometer Data Book” (published by Atago Co., Ltd.) The particles were dispersed in 2 ml to prepare a sample plate.
Next, each sample plate is set in an optical microscope and observed using a sodium lamp as a light source, and it is confirmed that the outline of the particles becomes invisible at a temperature where the refractive index of each liquid organic compound is known. The refractive index of the liquid organic compound used was defined as the refractive index of the particles.
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, as the refractive index, the value rounded to the fourth decimal place was adopted. In addition, in the case where the temperature is not particularly described such as p-diethylbenzene, the presence or absence of the outline of the particle was confirmed at 20 ° C.
In the following production examples, a monomer composition prepared separately in the same manner as in each production example was used, and after the monomers were radically polymerized into polymer particles, the polymer particles were condensed without polysiloxane oligomer condensation. Was taken out and washed with toluene, and the refractive index was measured as described above for a polysiloxane oligomer that had been completely washed away.
2. Method for measuring refractive index of transparent substrate resin A material obtained by pulverizing a transparent substrate resin in a particulate form (about 1 mg or less per one particle) was measured by the same method as in the case of the polymer particles.

(Method for confirming the coating state of composite particles)
Whether the polymer particles are exposed by a method of visually observing the composite particles with a microscope (used lens: 600 times) using a sodium lamp as a light source by dropping an aqueous dispersion of the composite particles on a glass slide. I confirmed it.

(Measurement method of aperture ratio)
First, 1 g of the composite particles was taken into a 50 ml magnetic crucible and calcined at 500 ° C. for 2 hours using an electric furnace (manufactured by ISUZU), and the composite particle silica shown in FIG. Partial particles (hereinafter referred to as silica particles) were obtained.
Next, the silica particles were gently taken out from the inside of the magnetic crucible with a spatula, and a photograph was taken with a scanning electron microscope (manufactured by JEOL Ltd .: JSM-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 portion were designated, and the projected area (S2) and the area (S1) of the opening portion of the silica particle were measured as illustrated in FIG.
From the measured areas, the aperture ratios of the individual silica particles were determined by the following formula, and the average value was shown in the examples.
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. 3, the value of h / D when the diameter of the silica particle is D and the height of the silica particle is h was 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. did. The value of D and h of each particle was measured with the image analysis apparatus, and h / D was calculated. In this specification, h / D means an average value of 50 h / Ds.

Production Example 1
To 200 g of water as an aqueous medium, 5 g of magnesium pyrophosphate by metathesis method is mixed as a suspension stabilizer and placed in a 500 ml separable flask. Further, 0.04 g of sodium lauryl sulfate as a surfactant and sublimation as a polymerization inhibitor. 0.02 g of sodium nitrate was dissolved in the dispersion medium.
Separately, 56 g of methyl methacrylate and 14 g of divinylbenzene as monofunctional polymerizable vinyl monomers, and MKC silicate MS57 (manufactured by Mitsubishi Chemical Corporation: average molecular weight 1300 to 1500 as polyalkoxysiloxane oligomer), wherein R is methyl, n The average of 15 to 18) was 30 g, and 2,2′-azobis (2,4-dimethylvaleronitrile) 0.25 g was uniformly dissolved as a polymerization initiator to prepare a monomer composition.
This monomer composition is added to the dispersion medium in the separable flask and stirred for about 10 seconds at 8000 rpm with a homomixer (trade name: ULTRA TURRAX T-25, manufactured by IKA) to finely disperse the monomer composition. It was. Next, a stirring blade, a thermometer and a reflux condenser are attached to the separable flask, and after replacing with nitrogen, the separable flask is placed in a constant temperature water bath (water bath) at 60 ° C., and the inside of the separable flask is continuously stirred at a stirring speed of 200 rpm. The polymerizable vinyl monomer was polymerized by suspension polymerization for 10 hours after the temperature of the dispersion medium to which the monomer composition in the bull flask was added reached 60 ° C. Next, 2 g of sodium hydroxide was added as a catalyst to condense the polyalkoxysiloxane oligomer.
Next, the separable flask is taken out from the constant temperature water bath, the reaction liquid in the separable flask is cooled to room temperature while stirring the separable flask, and hydrochloric acid is added until the pH of the slurry becomes about 2 to obtain a suspension stabilizer. The suspension stabilizer was removed by suction filtration with a Buchner funnel using filter paper and washed with 1.2 L of ion exchange water, and dried to obtain composite particles. In the obtained composite particles, a part of the surface of the polymer particles was exposed. The particle diameter was 20 μm.
The aperture ratio, h / D, and refractive index of the composite particles are shown in Table 1 below.

Production Example 2
Composite particles were obtained in the same manner as in Production Example 1 except that 56 g of styrene and 20 g of divinylbenzene were used as the polymerizable vinyl monomer. In the obtained composite particles, a part of the surface of the polymer particles was exposed. The particle diameter was 12 μm.
The aperture ratio, h / D, and refractive index of the composite particles are shown in Table 1 below.

Production Example 3
Composite particles were obtained in the same manner as in Production Example 1 except that MKC silicate MS58B15 (manufactured by Mitsubishi Chemical Corporation: average molecular weight 1600 to 1800) was used as the polyalkoxysiloxane oligomer. In the obtained composite particles, a part of the surface of the polymer particles was exposed. The particle diameter was 15 μm.
The aperture ratio, h / D, and refractive index of the composite particles are shown in Table 1 below.

Production Example 4
Production Example, except that 2 g of sodium sulfamate, which is an acid, is used as a catalyst for condensing the polyalkoxysiloxane oligomer instead of 2 g of sodium hydroxide, and the polymerization temperature is set to 80 ° C. using a thermostatic bath of 80 ° C. In the same manner as in Example 1, composite particles were obtained. In the obtained composite particles, a part of the surface of the polymer particles was exposed. The particle diameter was 20 μm.
The aperture ratio, h / D, and refractive index of the composite particles are shown in Table 1 below.

Production Example 5
Composite particles are obtained in the same manner as in Production Example 1 except that 35 g of methyl methacrylate, 21 g of styrene and 14 g of ethylene glycol dimethacrylate are used as the polymerizable vinyl monomer instead of 56 g of methyl methacrylate and 14 g of divinylbenzene. It was. In the obtained composite particles, a part of the surface of the polymer particles was exposed. The particle diameter was 20 μm.
The aperture ratio, h / D, and refractive index of the composite particles are shown in Table 1 below.

Production Example 6
Except for adding 20 g of methyl methacrylate as a polymerizable vinyl monomer, 5 g of divinylbenzene, 75 g of polyalkoxysiloxane oligomer, and adding 4 g of salt to water as a dispersion medium, the same as in Production Example 1 A composite particle was obtained. In the obtained composite particles, a part of the surface of the polymer particles was exposed. The particle diameter was 15 μm.
The aperture ratio, h / D, and refractive index of the composite particles are shown in Table 1 below.

Production Example 7
Composite particles were obtained in the same manner as in Production Example 1 except that 70 g of styrene was used instead of 56 g of methyl methacrylate and 14 g of divinylbenzene as the polymerizable vinyl monomer. In the obtained composite particles, a part of the surface of the polymer particles was exposed. The particle diameter was 12.5 μm.
The aperture ratio, h / D, and refractive index of the composite particles are shown in Table 1 below.

Comparative production example 1
A polymerization vessel equipped with a stirrer and a thermometer was charged with 500 g of deionized water in which 0.05 g of sodium lauryl sulfate was dissolved, and 50 g of tricalcium phosphate was added and dispersed. Next, a mixed solution prepared by dissolving 0.5 g of benzoyl peroxide and 0.5 g of azobisisobutyronitrile in 80 g of styrene as a polymerizable vinyl monomer and 20 g of divinylbenzene was put in a polymerization vessel. The liquid was dispersed with a K homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to adjust the droplets to about 12 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, washed, and dried to obtain true spherical polymer particles. The polymer particles had a particle diameter of 12 μm and a refractive index of 1.590.

Comparative production example 2
Spherical polymer particles were obtained in the same manner as in Comparative Production Example 1 except that the polymerizable vinyl monomer was changed to 80 g of methyl methacrylate and 20 g of divinylbenzene. The polymer particles had a particle diameter of 20 μm and a refractive index of 1.510.

Comparative production example 3
(Production of polymer-containing solution)
To a 300 ml four-necked flask equipped with a stirrer, a thermometer and a condenser tube, 144.5 g of tetramethoxysilane, 23.6 g of γ-methacryloxypropyltrimethoxysilane, 19 g of water, 30 g of methanol and Amberlyst 15 (Rohm and -5 g of a cation exchange resin manufactured by Hearth Japan Co., Ltd. was added and stirred at 65 ° C. for 2 hours for reaction. After the reaction mixture is cooled to room temperature, a distillation column is attached instead of the cooling pipe, and a cooling pipe and an outlet are provided. The temperature is increased to 80 ° C. under normal pressure over 2 hours, and the same temperature is maintained until methanol does not flow out. The reaction was allowed to proceed further. After cooling to room temperature again, Amberlyst 15 was filtered to obtain a polymerizable polysiloxane having a number average molecular weight of 1800.
Next, in a 1 liter flask equipped with a stirrer, a dripping port, a thermometer, a cooling tube and a nitrogen gas inlet, 200 g of toluene as an organic solvent was introduced, nitrogen gas was introduced, and the flask internal temperature was increased to 110 ° C. while stirring. Heated. Next, a solution obtained by mixing 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 6 g of 2,2′-azobisisobutyronitrile was added from the dropping port. It was dripped over 2 hours. After the dropwise addition, stirring was continued for 1 hour at the same temperature, and then 0.4 g of 1,1′-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane was added twice every 30 minutes. The copolymer was heated for 2 hours to obtain a polymer-containing solution in which a polymer having a number average molecular weight of 12000 was dissolved in toluene. The solid content in the obtained solution was 49.5% by weight.
(Production of composite particle dispersion)
Into a 1 liter four-necked flask equipped with a stirrer, two dropping ports (dropping ports 1 and 2) and a thermometer, 496 g of butyl acetate and 124 g of methanol were placed, and the internal temperature was adjusted to 20 ° C. Next, 10 g of the polymer-containing solution obtained above and 100 g of tetramethoxysilane (solution A) were mixed from the dropping port 1 while stirring in the flask, and a mixture of 30 g of water, 30 g of 25% aqueous ammonia and 60 g of methanol. (Solution B) was added dropwise from the dropping port 2 over 1 hour. After the dropping, stirring was continued for 2 hours until the same temperature. Further, the temperature inside the flask was raised to 100 ° C. under a pressure of 110 mmHg, and ammonia, methanol, toluene, and butyl acetate were distilled off until the solid concentration reached 30% by weight. A dispersion dispersed in butyl was obtained.
(Manufacture of composite particles)
A flask equipped with a stirrer, an inert gas introduction tube, a reflux condenser and a thermometer was charged with 900 g of deionized water in which 0.5 g of polyvinyl alcohol (PVA-205, manufactured by Kuraray Co., Ltd.) was dissolved. Next, a mixture containing 75 g of methyl methacrylate, 19 g of ethylene glycol dimethacrylate, 20 g of the composite particle dispersion and 1 g of azobisisobutyronitrile was charged into a flask. K. A uniform suspension was prepared by stirring at 3000 rpm for 5 minutes with a homogenizer (manufactured by Tokushu Kika Kogyo Co., Ltd.).
Next, the mixture was heated to 75 ° C. while blowing nitrogen gas, and the polymerization reaction was continued at this temperature for 5 hours, followed by cooling, filtration of the suspension, washing, and drying to obtain composite particles. The composite particles had a structure in which silica particles were dispersed in polymer particles derived from a polymerizable vinyl monomer. Moreover, the average particle diameter was 12 micrometers and the refractive index was 1.510.

Example 1
30 g of the composite particles obtained in Production Example 1 are added to 300 g of methyl methacrylate resin (MG-5, refractive index: 1.49) manufactured by Sumitomo Chemical Co., Ltd., blended for 3 minutes in a food mixer, and then injection molded. It was supplied to a machine and injection molded to obtain a molded body having a length of 100 mm, a width of 50 mm, and a thickness of 2 mm.
The transmittance, haze, and diffuse light transmittance of the above-mentioned molded product were measured by the above methods. The results are shown in Table 2 below.

Example 2
A molded body was obtained in the same manner as in Example 1 except that the amount of the composite particles added was 45 g with respect to 300 g of the methyl methacrylate resin. Further, the total light transmittance, haze and diffuse light transmittance were measured in the same manner as in Example 1. The results are shown in Table 2 below.

Example 3
As a composite particle, a molded body was obtained in the same manner as in Example 1, except that 3 g of the composite particle obtained in Production Example 2 was used with respect to 300 g of methyl methacrylate resin. Further, the total light transmittance, haze and diffuse light transmittance were measured in the same manner as in Example 1. The results are shown in Table 2 below.

Example 4
A molded body was obtained in the same manner as in Example 1 except that 30 g of the composite particle of Production Example 3 was used as 300 g of the methyl methacrylate resin. Further, the total light transmittance, haze and diffuse light transmittance were measured in the same manner as in Example 1. The results are shown in Table 2 below.

Example 5
A molded body was obtained in the same manner as in Example 1 except that the composite particles of Production Example 4 were used as the composite particles. Further, the total light transmittance, haze and diffuse light transmittance were measured in the same manner as in Example 1. The results are shown in Table 2 below.

Example 6
A molded body was obtained in the same manner as in Example 1 except that the composite particles of Production Example 5 were used as the composite particles. Further, the total light transmittance, haze and diffuse light transmittance were measured in the same manner as in Example 1. The results are shown in Table 2 below.

Example 7
A molded body was obtained in the same manner as in Example 1 except that 45 g of the composite particles of Production Example 6 were used as composite particles with respect to 300 g of methyl methacrylate resin. Further, the total light transmittance, haze and diffuse light transmittance were measured in the same manner as in Example 1. The results are shown in Table 2 below.

Example 8
A molded body was obtained in the same manner as in Example 1 except that 3 g of the composite particles of Production Example 7 were used as composite particles with respect to 300 g of methyl methacrylate resin. Further, the total light transmittance, haze and diffuse light transmittance were measured in the same manner as in Example 1. The results are shown in Table 2 below.

Comparative Example 1
A molded body was obtained in the same manner as in Example 1 except that 3 g of the polymer particles obtained in Comparative Production Example 1 were used with respect to 300 g of the methyl methacrylate resin instead of the composite particles. Further, the total light transmittance, haze and diffuse light transmittance were measured in the same manner as in Example 1. The results are shown in Table 2 below.

Comparative Example 2
A molded body was obtained in the same manner as in Example 1 except that 30 g of the polymer particles obtained in Comparative Production Example 2 were used with respect to 300 g of methyl methacrylate resin instead of the composite particles. Further, the total light transmittance, haze and diffuse light transmittance were measured in the same manner as in Example 1. The results are shown in Table 2 below.

Comparative Example 3
As a composite particle, a molded body was obtained in the same manner as in Example 1, except that 45 g of the composite particle obtained in Comparative Production Example 3 was used with respect to 300 g of methyl methacrylate resin. Further, the total light transmittance, haze and diffuse light transmittance were measured in the same manner as in Example 1. The results are shown in Table 2 below.

Comparative Example 4
A molded body was obtained in the same manner as in Example 1 using only methyl methacrylate resin without blending particles. Further, the total light transmittance, haze and diffuse light transmittance were measured in the same manner as in Example 1. The results are shown in Table 2 below.

  As is clear from Table 2, the light diffusing particle-containing molded product of the present invention has a high total light transmittance and a high haze as compared with those in which conventional polymer particles or composite particles are blended. Therefore, it is recognized that the diffused light transmittance is as high as 80% or more and diffused light is effectively transmitted.

  The light diffusing particle-containing molded product of the present invention includes a lighting fixture cover, a lens, a conductive plate, a video disc, a projection television screen and other optical components, a cosmetic container, a vending machine front plate, a signboard, a product display, a tabletop. It can be used for containers and the like.

The schematic sectional drawing which shows the light diffusable particle containing molded object of one Embodiment shape | molded by the sheet form. The schematic sectional drawing which shows the composite particle in the same embodiment. The schematic sectional drawing of the silica particle obtained by baking the composite particle in the same embodiment. Schematic for demonstrating the measuring method of an aperture ratio.

Explanation of symbols

1 ... Transparent substrate resin 2 ... Composite particles
2a ... polymer particles 2b ... silica coating

Claims (4)

A light diffusing particle-containing molded product obtained by blending light diffusing particles with a transparent base resin,
The light diffusing particles are polymer particles derived from a polymerizable vinyl monomer having a refractive index difference of 0.01 to 0.10 with respect to the transparent base resin, and a silica coating provided on the surface of the polymer particles. The silica coating is a composite particle comprising a polyalkoxysiloxane oligomer condensate,
(Formula) Diffuse light transmittance (%) = Total light transmittance (%) × Haze (%) × 0.01
A light diffusing particle-containing molded product, wherein the diffuse light transmittance value represented by the formula is 80% or more.   The light-diffusing particle-containing molded article according to claim 1, wherein the silica coating is provided such that the surface of the polymer particles is exposed with an opening ratio of 0.1 to 1.   The light diffusing particle-containing molded article according to claim 2, wherein the height h of the silica coating and the diameter D of the composite particles have a relationship of 0.5 ≦ h / D <1.   The compounding quantity of the said light diffusable particle is 0.1-20 weight part with respect to 100 weight part of said transparent base resin, The light diffusable particle containing molded object in any one of Claim 1 thru | or 3.

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