JP2014063120A - Light diffusing body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light diffusing body capable of being made thinner while securing sufficient optical transparency, light diffusion and light resistance.SOLUTION: The light diffusing body is formed from a light diffusing resin composition where resin particles and inorganic compounds are distributed in base resin. The resin particles are polymer particles which contain polymers of (meth)acrylic monofunctional monomers and monomer mixtures including polyfunctional monomers and which have a volume average particle diameter of 2 to 10 μm and a refraction index of 1.540 to 1.560. The inorganic compound is barium sulfate having a volume average particle diameter of 0.4 to 0.7 μm. The light diffusing resin compound contains the resin particles of 1.5 to 2.5 pts.wt. with respect to the light diffusing resin compound of 100 pts.wt. The contented weight ratio of the resin particles and the inorganic compounds in the light diffusing resin compound is in the range from 1:0.5 to 1:1.35.

Description

  The present invention relates to a light diffuser having light transparency and light diffusibility.

  Conventionally, a light diffuser made of a resin composition containing a base resin such as an acrylic resin, a polycarbonate resin, or a styrene resin is a light diffuser for diffusing light from a light source in a lighting fixture (for example, a light source). It is used as a lighting cover that covers

  Conventionally, fluorescent lamps or incandescent lamps have been widely used as light sources for lighting fixtures, but in recent years, LEDs have been used in place of fluorescent lamps and incandescent lamps for the purpose of extending the life. ing. While fluorescent lamps and incandescent lamps emit light in all directions, LEDs emit light forward and have higher directivity than fluorescent lamps and incandescent lamps. Moreover, in the lighting fixture which uses LED as a light source, although the illumination cover as a light diffuser is provided so that the some LED chip arranged on the board | substrate may be covered, for example, the light diffusion by this light diffuser is inadequate. If there is, the LED chip can be seen through the lighting cover, and the appearance is bad. For this reason, the light diffusing body for lighting fixtures using LED as a light source is required to have higher light diffusibility than the light diffusing body for lighting fixtures using fluorescent lamps or incandescent lamps as light sources.

  For example, Patent Document 1 discloses a polymer (A) obtained by polymerizing a monomer mainly composed of methyl methacrylate, a particulate inorganic compound (B), and a particulate crosslinked resin (C). A light diffusion plate for an LED light source comprising a methacrylic resin composition is disclosed.

  The light diffusion plate for an LED light source disclosed in Patent Document 1 has high light transmittance and light diffusibility. Therefore, in a lighting apparatus using an LED as a light source, sufficiently diffuses light from the LED, The light from the LED can be sufficiently transmitted while suppressing the LED chip from being seen through.

JP 2010-77179 A

  By the way, lighting covers (light diffusers) of lighting fixtures used in houses such as ceiling lights are required to be thin and light so that residents can easily remove them. In addition, a lighting cover of a lighting fixture used in a house is required to have sufficient light resistance against external light such as ultraviolet rays so that it can be used for a long time.

  However, the light diffusing plate for an LED light source disclosed in Patent Document 1 exhibits sufficient light diffusibility at a thickness of 3 mm, but cannot exhibit sufficient light diffusivity when it is thinner than 3 mm. Moreover, the light diffusion plate for LED light sources disclosed in Patent Document 1 is easily discolored under the influence of ambient light such as ultraviolet rays, and has poor light resistance.

  The present invention has been made in view of the above situation, and provides a light diffuser that can be thinned while ensuring sufficient light transmittance, light diffusibility, and light resistance. Objective.

  The light diffuser according to the present invention is a light diffuser comprising a light diffusing resin composition in which resin particles and an inorganic compound are dispersed in a base resin, and the resin particles are (meth) acrylic single particles. The inorganic compound is a polymer particle having a volume average particle diameter of 2 to 10 μm and a refractive index of 1.540 to 1.560 comprising a polymer of a monomer mixture containing a functional monomer and a polyfunctional monomer. Is a barium sulfate having a volume average particle diameter of 0.4 to 0.7 μm, and the light diffusing resin composition contains 1.5 parts of the resin particles with respect to 100 parts by weight of the light diffusing resin composition. The content ratio of the resin particles and the inorganic compound in the light diffusing resin composition is in a range of 1: 0.5 to 1: 1.35 in weight ratio. It is characterized by. In addition, in this specification, (meth) acryl means methacryl or acryl.

  This light diffuser of the present invention is a resin having a predetermined refractive index and a volume average particle diameter, which is a polymer of a monomer mixture containing a (meth) acrylic monofunctional monomer and a polyfunctional monomer. By containing particles and barium sulfate having a predetermined volume average particle diameter in a predetermined ratio, the light transmittance and light can be reduced with a thinner thickness (specifically, a thickness of 2 mm) than before. It has diffusibility and has excellent light resistance to light such as ultraviolet rays.

  ADVANTAGE OF THE INVENTION According to this invention, the light diffusing body which can be reduced in thickness can be provided, ensuring sufficient light transmittance, light diffusibility, and light resistance.

FIG. 1 is a graph showing the diffusibility of transmitted light in the light diffuser according to the first embodiment of the present invention.

[Light Diffuser of the Present Invention]
The light diffuser of the present invention is formed by molding a light diffusing resin composition in which resin particles and an inorganic compound are dispersed in a base resin.

  Although it will not specifically limit if the said base resin is transparent resin, It is preferable that it is resin with a refractive index difference with the said resin particle about 0.05-0.07, for example, acrylic resin. Examples of the acrylic resin that can be used as the base resin include resins obtained by polymerizing methyl methacrylate as a main component. Monomers copolymerizable with methyl methacrylate that can form the acrylic resin include methyl acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth) (Meth) acrylic such as 2-ethylhexyl acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate, diethylaminoethyl (meth) acrylate Multifunctional (meth) acrylates such as acid esters, (meth) acrylic acids, ethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, allyl (meth) acrylate, neopentyl glycol di (meth) acrylate , Styrene, α-methylstyrene, etc. Aromatic vinyl monomers, phenylmaleimide, maleimide and cyclohexyl maleimide, but maleic anhydride and the like, but is not limited thereto. In the present specification, (meth) acrylate means methacrylate or acrylate.

  The resin particles are polymer particles made of a polymer of a monomer mixture containing a (meth) acrylic monofunctional monomer and a polyfunctional monomer.

  The (meth) acrylic monofunctional monomer means a (meth) acrylic monomer having one ethylenically unsaturated group. Examples of the (meth) acrylic monofunctional monomer include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, and acrylic acid. 2-ethylhexyl, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, benzyl acrylate, cyclohexyl 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, 2-chloroethyl methacrylate, phenyl methacrylate, benzyl methacrylate, methacrylate Cyclohexyl acid, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-methacrylic acid 2- (Meth) acrylic acid esters such as hydroxypropyl and 2-hydroxybutyl methacrylate, (meth) acrylic acid derivatives such as acrylonitrile, methacrylonitrile, acrylamide and methacrylamide, acrylic acid, methacrylic acid and the like. In the present invention, methyl methacrylate is preferable because desired light transmittance and light diffusibility can be obtained. These (meth) acrylic monofunctional monomers may be used alone or in combination of two or more.

  The polyfunctional monomer means a polyfunctional monomer having two or more ethylenically unsaturated groups. Examples of the polyfunctional monomer include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, and nonaethylene glycol di (meth). ) Acrylate, tetradecaethylene glycol di (meth) acrylate, decaethylene glycol di (meth) acrylate, pentadecaethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, tetrapropylene glycol di (meth) acrylate, 1 , 3-butylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanedio Rudi (meth) acrylate, allyl methacrylate, glycerin di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, diethylene glycol di (meth) acrylate phthalate, caprolactone-modified dipentaerythritol (Meth) acrylate polyfunctional monomers such as hexa (meth) acrylate, caprolactone-modified hydroxypivalate ester neopentyl glycol diacrylate, polyester acrylate, urethane acrylate; divinylbenzene, divinylnaphthalene, diallylphthalate and their derivatives Aromatic vinyl polyfunctional monomers that are: Among these polyfunctional monomers, it is preferable to use (meth) acrylic acid ester polyfunctional monomers. When a (meth) acrylic acid ester polyfunctional monomer is used as the polyfunctional monomer, the light resistance can be improved in the light diffuser. In the present invention, these polyfunctional monomers may be used alone or in combination of two or more.

  The content of the polyfunctional monomer in the monomer mixture is a content that can realize a refractive index of 1.540 to 1.560 of resin particles obtained by polymerizing the monomer mixture. Although not particularly limited, it is preferably 0.5 to 50 parts by weight and more preferably 3 to 30 parts by weight with respect to 100 parts by weight of the monomer mixture. When the content of the polyfunctional monomer in the monomer mixture is less than 0.5 parts by weight with respect to 100 parts by weight of the monomer mixture, the monomer mixture is polymerized. The obtained resin particles do not have sufficient heat resistance, and the resin particles may be dissolved during melt-kneading into the base resin. On the other hand, when the content of the polyfunctional monomer in the monomer mixture exceeds 50 parts by weight with respect to 100 parts by weight of the monomer mixture, the content of the polyfunctional monomer Since the effect of improving the heat resistance of the resin particles commensurate with the above cannot be obtained, the cost may increase.

  If the monomer mixture can realize a refractive index of 1.540 to 1.560 of polymer particles (resin particles) made of a polymer of the monomer mixture, the (meth) acrylic monofunctional monomer described above In addition to the above-described (meth) acrylic monofunctional monomer and polyfunctional monomer, other monomers may be included. You may go out. For example, when the styrene monofunctional monomer is added to the monomer mixture in addition to the (meth) acrylic monofunctional monomer and the polyfunctional monomer, the refractive index is 1.540. ~ 1.560 polymer particles can be obtained.

  The styrene monofunctional monomer means a styrene monomer having one ethylenically unsaturated group. As the styrenic monofunctional monomer, any of styrene and substituted styrene (substituent includes lower alkyl, halogen atom (especially chlorine atom) and the like) can be used. Specifically, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, p- n-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, 3, 4-dichlorostyrene, α-methylstyrene, and the like can be used. In the present invention, styrene is preferable because desired light transmittance and light diffusibility can be obtained. These styrene monofunctional monomers may be used alone or in combination of two or more.

  In addition, the content ratio of the styrene monofunctional monomer and the (meth) acrylic monofunctional monomer in the monomer mixture is a polymer particle composed of a polymer of the monomer mixture ( The ratio is not particularly limited as long as the refractive index of the resin particles is 1.540 to 1.560.

  The resin particles used in the present invention can be produced by polymerizing the monomer mixture by a known polymerization method. Specific polymerization methods include solution polymerization, suspension polymerization, seed polymerization and the like. Here, when the resin particles are produced by polymerizing the monomer mixture by seed polymerization, the resin particles contain any component derived from the seeds unless the desired physical properties are affected. Also good. In addition, by using these production methods, the ratio of various monomer components in the resin particles can be an intended ratio (mixing ratio of monomer components).

  The volume average particle diameter of the resin particles used in the present invention is in the range of 2 to 10 μm, and more preferably in the range of 2 to 8 μm. If the volume average particle diameter of the resin particles is less than 2 μm, there is a possibility that sufficient light transmission cannot be obtained in the light diffuser. If it exceeds 10 μm, sufficient in the light diffuser There is a possibility that light diffusibility cannot be obtained.

  Moreover, the variation coefficient (CV value) of the particle diameter of the resin particles used in the present invention is not particularly limited, but is preferably 20 to 50%, and more preferably 25 to 40%. When the CV value of the resin particles is 25 to 40%, the ratio of the particles having a small particle diameter to the particles having a large particle diameter becomes appropriate, and in the light diffuser, while ensuring a sufficient total light transmittance. The light diffusibility can be further improved.

  Moreover, the refractive index of the resin particles used in the present invention is in the range of 1.540 to 1.560, and more preferably in the range of 1.545 to 1.555. When the refractive index of the resin particles is less than 1.540, there is a possibility that sufficient light diffusibility cannot be obtained in the light diffuser. When the thickness is reduced (specifically, when the thickness is 2 mm), there is a possibility that sufficient light transmission and light resistance cannot be obtained.

  Moreover, in this invention, content of the said resin particle with respect to the said base resin in the said light diffusable resin composition is 1.5-2.5 weight part with respect to 100 weight part of said base resin, More preferably, it is 1.5 to 2.0 parts by weight. When the content of the resin particles is less than 1.5 parts by weight with respect to 100 parts by weight of the base resin, there is a possibility that sufficient light permeability and light diffusibility cannot be obtained in the light diffuser. is there. Moreover, when content of the said resin particle exceeds 2.5 weight part with respect to 100 weight part of said base resin, there exists a possibility that the light resistance of the light diffuser which consists of a light diffusable resin composition may worsen. .

  In the present invention, barium sulfate having a volume average particle diameter of 0.4 to 0.7 μm, preferably 0.5 to 0.62 μm is used as the inorganic compound. When the particle diameter of barium sulfate used as the inorganic compound is less than 0.4 μm, sufficient light transmission is obtained when the light diffuser is thinned (specifically, when the thickness is 2 mm). When the thickness exceeds 0.7 μm, there is a possibility that sufficient light diffusibility cannot be obtained when the light diffuser is thinned (specifically, when the thickness is 2 mm). There is a possibility that the balance between the light diffusibility and the light transmittance in the light diffuser is deteriorated.

  In the present invention, the CV value of barium sulfate used as the inorganic compound is not particularly limited, but is preferably 50 to 70%, and more preferably 55 to 70%. When the CV value of the barium sulfate is 50 to 70%, the ratio of particles having a small particle diameter to particles having a large particle diameter becomes appropriate, and the light diffuser of the present invention has a sufficient total light transmittance. While ensuring, light diffusibility can be improved more.

In the present invention, the specific surface area of barium sulfate used as the inorganic compound is preferably in the range of 3 to 5 m ² / g, and more preferably in the range of 3 to 4 m ² / g. When the specific surface area of barium sulfate is in the range of 3 to 5 m ² / g, the light diffusibility can be further improved while ensuring sufficient total light transmittance in the light diffuser of the present invention.

  Moreover, in this invention, content of barium sulfate with respect to the said resin particle in the said light diffusable resin composition is 0.5-1.35 weight part with respect to 1 weight part of said resin particles, Preferably, it is 0.8. 6 to 1.33 parts by weight. That is, in the present invention, the content ratio of the resin particles and barium sulfate (inorganic compound) in the light diffusing resin composition is in a range of 1: 0.5 to 1: 1.35 by weight. . When the content of barium sulfate in the light diffusing resin composition is less than 0.5 parts by weight with respect to 1 part by weight of the resin particles, sufficient light diffusibility can be obtained in the light diffuser. It may not be possible. Further, when the content of barium sulfate in the light diffusing resin composition is more than 1.35 parts by weight with respect to 1 part by weight of the resin particles, the light diffuser has a sufficient total light transmittance. There is a possibility that it cannot be secured.

  Moreover, the content of barium sulfate relative to the base resin in the light diffusing resin composition is not particularly limited, but is 1.0 to 2.5 parts by weight with respect to 100 parts by weight of the base resin. Is preferable, and it is more preferable that it is 1.5-2.5 weight part. When the content of barium sulfate in the light diffusing resin composition is in the range of 1.0 to 2.5 parts by weight with respect to 100 parts by weight of the base resin, sufficient light transmission of the light diffuser The light diffusibility can be further improved while ensuring the properties and light resistance.

  In the light diffuser of the present invention, the light diffusing resin composition preferably includes a rubber component. By containing a rubber component in the light diffusing resin composition, the strength of the light diffusing body can be improved. Examples of the rubber component that can be used in the present invention include core-shell type rubber particles, cross-linked acrylonitrile butadiene rubber particles, cross-linked styrene butadiene rubber particles, and acrylic rubber particles. The core-shell type rubber particles are rubber particles having a core layer and a shell layer. For example, a two-layer structure in which an outer shell layer is made of a glassy polymer and an inner core layer is made of a rubbery polymer, or Examples include a three-layer structure in which the outer shell layer is made of a glassy polymer, the intermediate layer is made of a rubbery polymer, and the core layer is made of a glassy polymer. The glass layer is made of, for example, a polymer of methyl methacrylate, and the rubbery polymer layer is made of, for example, a butyl acrylate polymer (butyl rubber). These rubber components (rubber particles) may be used alone or in combination of two or more. Specific examples of the core-shell type rubber particles include “Staffyroid (registered trademark) AC3832”, “Staffyloid (registered trademark) AC3816N” manufactured by Ganz Kasei Co., Ltd., and the like. Specific examples of the crosslinked acrylonitrile butadiene rubber (NBR) particles include “XER-91” (average particle size of 0.5 μm) manufactured by JSR Corporation. Specific examples of the crosslinked styrene butadiene rubber (SBR) particles include “XSK-500” (average particle size 0.5 μm) manufactured by JSR Corporation. Specific examples of the acrylic rubber particles include “Metablene (registered trademark) W-300A” (average particle size 0.1 μm) and “Metablene (registered trademark) W450A” (average particle size 0.2 μm) manufactured by Mitsubishi Rayon Co., Ltd. ) And the like. Among the rubber components described above, the acrylic rubber particles are preferable from the viewpoint of transparency when kneaded into a base resin (for example, an acrylic resin). The average particle diameter of the rubber component is preferably in the range of 0.005 to 0.3 μm, more preferably 0.05, from the viewpoint of transparency when kneaded into the base resin (for example, acrylic resin). It is in the range of ˜0.3 μm.

  Moreover, the content of the rubber component in the light diffusing resin composition is preferably 1 to 10 parts by weight, and more preferably 2 to 5 parts by weight with respect to 100 parts by weight of the base resin. If the rubber component content is less than 1 part by weight with respect to 100 parts by weight of the base resin, the strength of the light diffuser may not be sufficiently improved, and more than 10 parts by weight. If the amount is too large, the light transmittance of the light diffuser may be reduced.

  In the light diffuser of the present invention, the light diffusing resin composition contains a small amount of other resin components as long as the desired physical properties such as light transmission, light diffusibility, and light resistance are not affected. May be. For example, the light diffusing resin composition may contain various components such as a fluorescent brightening agent, a heat stabilizer, an ultraviolet absorber, and an antistatic agent. In the present invention, these various components can give the light diffusing resin composition physical properties such as desired fluorescent whitening, thermal stability, and ultraviolet absorption.

  In the present invention, the fluorescent whitening agent is not particularly limited, and for example, an oxazole fluorescent whitening agent (for example, “Kayalite (registered trademark) OS” manufactured by Nippon Kayaku Co., Ltd.), imidazole fluorescent A brightener or a rhodamine fluorescent brightener can be used. Such a fluorescent whitening agent is preferably 0.0005 to 0.1 parts by weight, more preferably 0.001 to 0.1 parts by weight with respect to 100 parts by weight of the base resin in the light diffusing resin composition. When it is included at a ratio of parts by weight, more preferably 0.001 to 0.05 parts by weight, the fluorescent whitening property can be imparted to the light diffusing resin composition.

  In the present invention, the heat stabilizer is not particularly limited, and examples thereof include organic phosphorus heat stabilizers such as phosphate esters, phosphite esters, and phosphonate esters; hindered phenol heat stabilizers; lactones. A phosphite antioxidant (for example, “ADEKA STAB (registered trademark) PEP-36” manufactured by ADEKA Corporation) having a function of suppressing thermal oxidation can be used. Such a heat stabilizer is preferably 0.005 to 0.5 parts by weight, more preferably 0.01 to 0.5 parts by weight with respect to 100 parts by weight of the base resin in the light diffusing resin composition. When included in a proportion of 0.001 to 0.3 parts by weight, more preferably, the light diffusing resin composition can be provided with thermal stability.

  In the present invention, the ultraviolet absorber is not particularly limited. For example, a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber (for example, “Adekastab (registered trademark) LA-31” manufactured by ADEKA Corporation). ), Hydroxyphenyltriazine-based ultraviolet absorbers and the like can be used. Such an ultraviolet absorber is preferably 0.01 to 2.0 parts by weight, more preferably 0.03 to 2.0 parts by weight with respect to 100 parts by weight of the base resin in the light diffusing resin composition. Part, more preferably 0.05 to 1.0 part by weight, it is possible to impart ultraviolet absorptivity to the light diffusing resin composition.

  In the present invention, the antistatic agent is not particularly limited, and a bleed-out type antistatic agent that exhibits antistatic performance by bleeding out, and exhibits antistatic performance permanently without bleeding out. Any permanent antistatic agent can be used.

  The bleed-out antistatic agent is not particularly limited, and examples thereof include cationic, anionic, betaine (zwitterionic), and nonionic surfactants. Among these surfactants, alkylbenzene sulfonate, alkyl sulfonate, and glycerin fatty acid ester are preferable. Examples of the alkyl sulfonate include “Electro Stripper (registered trademark) PC” manufactured by Kao Corporation, and examples of the glycerin fatty acid ester include “Dasper K200” manufactured by Miyoshi Oil & Fat Co., Ltd. Can do. Such surfactants (bleed-out type antistatic agents) may be used alone or in combination of two or more. Such a surfactant (bleed-out type antistatic agent) is added in an amount of 0.1 to 3 parts by weight, more preferably 0.5 to 1.5 parts by weight with respect to 100 parts by weight of the base resin. When included, it becomes possible to impart sufficient antistatic performance to the light diffusing resin composition without changing the color of the light diffusing resin composition.

  Further, the permanent antistatic agent is not particularly limited, but a block copolymer composed of a hydrophilic block and a hydrophobic block is preferable from the viewpoint of obtaining a permanent antistatic performance when added in a small amount.

  A block copolymer consisting of a hydrophilic block and a hydrophobic block is one in which a hydrophilic block and a hydrophobic block are alternately and repeatedly bonded through bonds such as ester bonds, imide bonds, amide bonds, ether bonds, and urethane bonds. Examples of the hydrophobic block include polyolefin, and examples of the hydrophilic block include polyether, polyether-containing hydrophilic polymer, cationic polymer, and anionic polymer.

  For the polyether as the hydrophobic block, polyether diol, polyether diamine, and modified products thereof can be used. The polyether-containing hydrophilic polymer as a hydrophobic block includes a polyether ester amide having a polyether diol segment as a polyether segment forming component, a polyether amide imide having a polyether diol segment, and a polyether diol segment. A polyether ester having a polyether diamine, a polyether amide having a polyether diamine segment, a polyether diol or a polyether urethane having a polyether diamine segment can also be used. As the cationic polymer as the hydrophobic block, a cationic polymer having a cationic group in the molecule can be used. Examples of the cationic group include groups having a quaternary ammonium salt and a phosphonium salt. As an anionic polymer as a hydrophobic block, an anionic polymer having a dicarboxylic acid having a sulfonic acid group and a diol or a polyether as essential constituent units and having 2 to 80 sulfonic acid groups in the molecule is used. it can.

  Specific examples of the block copolymer comprising a hydrophilic block and a hydrophobic block as described above include “Pelestat (manufactured by Sanyo Chemical Industries, Ltd.), which is a block copolymer having a polyether block and a polyolefin block in the molecule. Registered trademark) 230 "(refractive index 1.50).

  When the permanent antistatic agent as described above is contained in the light diffusing resin composition in an amount of preferably 2 to 20 parts by weight, more preferably 5 to 15 parts by weight with respect to 100 parts by weight of the base resin. Sufficient antistatic performance can be permanently imparted to the light diffusing resin composition.

  The light diffuser of the present invention is not limited by the production method thereof, but the base resin, the resin particles, the inorganic compound, and other additives (for example, a fluorescent whitening agent) as necessary. A light diffusing resin composition obtained by mixing and kneading a predetermined amount of a heat stabilizer, an ultraviolet absorber, or an antistatic agent, etc., is preferably produced by extrusion molding. . The mixing and kneading can be performed by, for example, a ribbon blender, a Henschel mixer, a Banbury mixer, a drum tumbler, a single screw extruder, a twin screw extruder, a multi-screw extruder, or the like. The temperature condition for the kneading is usually 240 to 300 ° C. The mixture obtained by mixing and kneading is molded into a pellet by an extrusion molding method to obtain a pellet-like light diffusing resin composition. A plate-like light diffusing body (light diffusing plate) can be obtained by extrusion molding into a shape. Alternatively, a plate-like light diffuser (light diffusion plate) can be obtained by molding the light diffusing resin composition obtained by mixing and kneading into a plate shape by an extrusion molding method. Furthermore, various shapes of light diffusers can be obtained by vacuum forming or pressure forming the plate-like light diffuser (light diffuser plate).

  The light diffuser of the present invention preferably exhibits a total light transmittance of 55% or more, more preferably 55 to 65%, preferably 55 ° or more, more preferably 55 to 60, when the thickness is 2 mm. Degree of dispersion of °. In addition, when the thickness of the light diffuser of the present invention is 2 mm, the color difference (hunter ΔE) after exposure for 200 hours, which is determined by the method for measuring the color difference after accelerated exposure described later, is preferably less than 3. More preferably, it is less than 1.

  Such a light diffuser of the present invention is thin (specifically, when the thickness is 2 mm) and exhibits high total light transmittance and dispersity. For example, a luminaire having an LED light source (for example, When used as a light diffuser of general lighting devices, lighting displays, lighting signs, and the like, the light from the LED light source can be sufficiently diffused. Furthermore, it has excellent light resistance, and has high durability as at least a light diffuser for indoor lighting equipment. In addition, the light diffuser not only for indoor use but also for outdoor lighting fixtures has a small color difference (hunter ΔE) after exposure for 200 hours, for example, a color difference (hunter ΔE) of less than 1. Even so, it has high durability.

  The thickness of the light diffuser of the present invention is not particularly limited, but is excellent in light diffusibility by being set to 1.0 to 3.0 mm, more preferably 1.4 to 2.0 mm. , Can exhibit light transmittance and light resistance.

  The light diffuser of the present invention can be used as an illumination cover for covering a light source in a lighting apparatus using various light sources such as a fluorescent lamp and a light emitting diode (LED). The shape of the light diffuser of the present invention is not particularly limited, and can be various shapes depending on the application. For example, when the light diffuser of the present invention is used as a lighting cover, the shape of the light diffuser can be a semi-cylindrical shape, a flat plate shape, or a dome shape.

  Hereinafter, physical properties of the light diffuser according to the embodiment of the present invention will be described in detail.

  First, a method for measuring the volume average particle diameter of the resin particles and barium sulfate used in the manufacture of the light diffuser according to the embodiment of the present invention, and a method for calculating the coefficient of variation (CV value) of the particle diameter of the resin particles and barium sulfate. The method for measuring the specific surface area of barium sulfate, the method for measuring the refractive index of the resin particles, and the method for measuring the color difference after accelerated exposure will be described.

[Method for measuring volume average particle diameter of resin particles]
The volume average particle diameter of the polymer particles was calculated by filling the electrolyte solution into pores having a pore diameter of 20 to 400 μm and determining the volume from the change in conductivity of the electrolyte solution when the particles pass through the electrolyte solution. Specifically, the volume average particle size of the resin particles is the volume average particle size (arithmetic in the volume-based particle size distribution) measured using a Coulter type precision particle size distribution analyzer “Multisizer III” (manufactured by Beckman Coulter, Inc.). Average diameter). In measurement, according to “Reference MANUAL FOR THE COULTER MULTISIZER” (1987) published by Coulter Electronics Limited, multisizer III is calibrated and measured using an aperture suitable for the particle diameter of the particles to be measured.

  Specifically, 0.1 g of resin particles are dispersed in 10 ml of 0.1 wt% nonionic surfactant solution using a touch mixer and ultrasonic waves to obtain a dispersion. In a beaker filled with the measurement electrolyte “ISOTON (registered trademark) II” (manufactured by Beckman Coulter, Inc.) provided in the “Multisizer III” main body, the dispersion is dropped with a dropper while gently stirring. Adjust the concentration meter reading on the Multisizer III screen to around 10%. Next, the aperture size (diameter), current (aperture current), gain (gain), and polarity (polarity of the inner electrode) are set on the “Multisizer III” main body. REFERENCE MANUAL FOR THE COULTER MULTIZ (198) And measure the volume-based particle size distribution in manual (manual mode). During the measurement, the beaker is stirred gently to the extent that bubbles do not enter, and the measurement ends when the particle size distribution of 100,000 particles is measured. The volume average particle diameter of the resin particles is an average value of the measured particle diameters of 100,000 particles, and means an arithmetic average diameter in a volume-based particle size distribution.

[Method for measuring volume average particle diameter of barium sulfate]
The volume average particle diameter of barium sulfate (arithmetic average diameter in a volume-based particle size distribution) is measured with a laser diffraction / scattering particle size distribution measuring device (“LS 13 320 type” manufactured by Beckman Coulter, Inc.). Specifically, 0.1 g of barium sulfate and 10 ml of a 1% by weight sodium pyrophosphate aqueous solution are put into a test tube and mixed for 2 seconds with a touch mixer (manufactured by Yamato Kagaku Co., Ltd., “TOUCHMIXER MT-31”). Thereafter, barium sulfate in the test tube is dispersed for 10 minutes using a commercially available ultrasonic cleaner (manufactured by Velvo Crea, “ULTRASONIC CLEANER VS-150”) to obtain a dispersion. While irradiating the dispersion with ultrasonic waves, the volume average particle diameter of barium sulfate in the dispersion (arithmetic average diameter in the volume-based particle size distribution) is measured with the laser diffraction scattering particle size distribution measuring apparatus. The optical model at the time of measurement is adjusted to the refractive index (1.64) of the barium sulfate to be measured.

[Calculation method of CV value of resin particles and barium sulfate]
The CV value of each of the resin particles and barium sulfate is calculated from the standard deviation (σ) and volume average particle diameter (x) when the above-mentioned volume-based particle size distribution is measured by the following formula.

  CV value (%) = (σ / x) × 100

[Method for measuring specific surface area of barium sulfate]
The specific surface area of barium sulfate is measured by the BET method (nitrogen adsorption method) described in JIS R1626. For the barium sulfate to be measured, the BET nitrogen adsorption isotherm was measured using an automatic specific surface area / pore distribution measuring device Tristar 3000 manufactured by Shimadzu Corporation, and the specific surface area was determined from the nitrogen adsorption amount using the BET multipoint method. Is calculated. The nitrogen adsorption isotherm was measured using nitrogen as an adsorbate and a constant volume method under the condition of an adsorbate cross section of 0.162 nm ² .

[Measurement method of refractive index of resin particles]
The refractive index of the resin particles was measured by the Becke method. In the refractive index measurement by the Becke method, resin particles are placed on a slide glass, and a refractive liquid (CARGILLE: Cargill standard refractive liquid, a refractive liquid having a refractive index of 1.538 to 1.562 is obtained with a refractive index difference of 0.1. A plurality of preparations in 002 increments) are dropped. After thoroughly mixing the resin particles and the refraction liquid, from the bottom, irradiate light from a high-pressure sodium lamp (model number “NX35”, center wavelength 589 nm) manufactured by Iwasaki Electric Co., Ltd. Was observed. And when the outline was not visible, it was judged that the refractive index of a refractive liquid and a resin particle is equal.

  The observation with an optical microscope is not particularly problematic as long as it is an observation at a magnification at which the outline of the resin particles can be confirmed. However, if the particles have a particle diameter of 5 μm, it is appropriate to observe at a magnification of about 500 times. By the above operation, the closer the refractive index of the resin particle to the refractive liquid, the more difficult it is to see the outline of the resin particle. Therefore, it is determined that the refractive index of the refractive liquid that is most difficult to understand the resin particle outline is equal to the refractive index of the resin particle. did.

  In addition, when there is no difference in the appearance of the resin particles between the two types of refractive liquid having a refractive index difference of 0.002, the intermediate value of the refractive indexes of the two types of refractive liquid is set as the refractive index of the resin particles. Judged. For example, when the test is performed with each of the refractive liquids having the refractive indexes of 1.554 and 1.556, if there is no difference in the appearance of the resin particles between the two refractive liquids, an intermediate value of the refractive index of these refractive liquids is 1.555. Was determined as the refractive index of the resin particles.

  Next, a method for measuring the total light transmittance and dispersion of the light diffuser according to the embodiment of the present invention will be described. In the measurement of the total light transmittance and the degree of dispersion, a plate-like light diffuser (light diffusion plate) having a thickness of 2 mm and 50 mm × 100 mm obtained in Examples and Comparative Examples described later is used as a measurement target.

[Measurement method of total light transmittance of light diffuser]
The total light transmittance of the light diffuser is measured according to JIS K 7361. Specifically, the total light transmittance is measured using “NDH-4000” manufactured by Nippon Denshoku Industries Co., Ltd. With the number of measurement samples n = 10, the average value of the total light transmittance (%) of these ten measurement samples is calculated, and this average value is taken as the total light transmittance (%) of the light diffuser.

[Measurement method of dispersion degree of light diffuser]
The dispersity (D50) of the light diffuser is determined by the following procedure using an automatic goniophotometer (Goniophotometer GP-200 manufactured by Murakami Color Research Laboratory).

  A straight beam from the light source of the automatic goniophotometer is applied from the normal direction of the light diffuser installed at a distance of 75 cm from the light source. The intensity of light transmitted through the light diffuser is measured with a movable light receiver. This intensity is converted into transmittance, and the transmittance is plotted on a graph corresponding to the angle from the normal direction. From this graph, the angle at which the transmittance of light in the normal direction (straight light transmittance) is 50% is obtained. This angle is referred to as the degree of dispersion (D50). The unit of the degree of dispersion (D50) is “° (degree)”. Moreover, it means that it is excellent in diffusibility, so that dispersion degree (D50) is large.

  Next, a method for measuring a color difference after accelerated exposure of a light diffuser according to an embodiment of the present invention will be described. In the measurement of the color difference after accelerated exposure, a plate-like light diffuser (light diffusion plate) having a thickness of 2 mm and 50 mm × 100 mm obtained in Examples and Comparative Examples described later is used as a test piece.

[Measurement method of color difference after accelerated exposure]
First, the Hunter value (E ₀ ) of the test piece is measured by the color measuring method shown below. Subsequently, the accelerated exposure test shown below was performed, and the Hunter value (E ₁ ) of the test piece after the accelerated exposure test was measured by the color measuring method shown below. Then, the difference (E ₁ -E ₀ ) between the hunter value (E ₀ ) of the test piece before the accelerated exposure test and the hunter value (E ₁ ) of the test piece after the accelerated exposure test is calculated as the color difference ( Hunter ΔE value).

-Accelerated exposure test-
The accelerated exposure test of the light diffuser was performed in accordance with JIS K7350-2 (Plastic-Exposure test method using a laboratory light source-Part 2: Xenon arc lamp). Specifically, the test piece was exposed with a xenon arc lamp for 200 hours under the following test conditions.

<Test conditions>
Irradiation device: Super Xenon Weather Meter SX75 (manufactured by Suga Test Instruments Co., Ltd.)
Irradiation conditions: Black panel temperature (63 ° C), no darkening, no spraying, outer filter # 275
Wavelength range: 300 to 400 nm
Irradiance: 180 W / m ²
Test piece: thickness 2 mm, 50 mm × 100 mm
Test tank: temperature (28-32 ° C), humidity (45-55%)

-Color measurement method-
The measurement of color was performed in accordance with JIS Z8722 (color measurement method—reflective and transmissive object color). Specifically, under the following measurement conditions, the color of the test piece was measured on a white plate dedicated to the reference presser, and the Hunter value was obtained.

<Measurement conditions>
Measuring device: spectroscopic colorimeter SE-2000 (manufactured by Nippon Denshoku Industries Co., Ltd.)
Color management software Color Mate 5 (Nippon Denshoku Industries Co., Ltd.)
Tristimulus value of standard plate (C / 2): Y = 96.09, X = 94.13, Z = 113.36
Standard presser white plate: Y = 76.5, X = 75.4, Z = 84.6
Measurement method: Reflection method Light source: C / 2 ° viewing condition measurement

  Subsequently, the manufacturing method of the resin particle (A) used for manufacture of the light diffusing body of Examples 1-6 of this invention and the resin particle (B) is demonstrated.

[Production Method of Resin Particle (A)]
A stainless steel beaker having a volume of 5 L was charged with 3000 g of pure water, 1.5 g (500 ppm) of sodium lauryl sulfate, and 90 g of magnesium pyrophosphate to prepare an aqueous phase.

  In a stainless beaker different from the stainless beaker used for the preparation of the aqueous phase, 400 g of methyl methacrylate as a (meth) acrylic monofunctional monomer, 500 g of styrene as a styrenic monofunctional monomer, and polyfunctional 100 g of divinylbenzene (DVB) as a monomer, 3 g of n-dodecyl mercaptan as a chain transfer agent, 7 g of 2,2-azobis- (2,4-dimethylvaleronitrile) as a polymerization initiator, tert- Butyl peroxy-2-ethylhexanoate (4 g) was added and stirred well to prepare an oil phase.

  The prepared oil phase was added to the previously prepared aqueous phase, and the mixture was stirred at 8000 rpm for 15 minutes using a TK homomixer manufactured by PRIMIX Co., Ltd. to obtain a suspension. The resulting suspension is then transferred to a 5 L reactor equipped with a stirrer and thermometer, after which the monomer is polymerized at 60 ° C. for 5 hours and then heated at 110 ° C. for 2 hours. After cooling to 30 ° C., a resin particle slurry was obtained. Next, hydrochloric acid was added to the resin particle slurry until the pH of the slurry was 2 or less. Next, the resin particle slurry to which hydrochloric acid was added was washed using a centrifugal dehydrator until the pH of the washing water became 6 to 7, and then dehydrated. The dehydrated cake thus obtained was vacuum-dried at a jacket temperature of 60 ° C. for 20 hours using a vacuum dryer. Next, it passed through a 400-mesh sieve to obtain resin particles (A).

  The volume average particle diameter of the resin particles (A) was 5.4 μm as measured by the above measuring method. The CV value of the resin particles (A) was 37.9% when calculated by the above calculation method. Further, the refractive index of the resin particles (A) was 1.555 as measured by the measurement method described above.

[Production Method of Resin Particle (B)]
Resin particles (B) were obtained in the same manner as in the method for producing resin particles (A) except that the amount of methyl methacrylate used was 550 g and the amount of styrene used was 350 g. The volume average particle diameter of the resin particles B was 5.8 μm as measured by the above measuring method. The CV value of the resin particles (B) was 33.9% when calculated by the above calculation method. Moreover, the refractive index of this resin particle (B) was 1.540 when measured by the above-mentioned measuring method.

  Next, the production of the resin particles (C) used for producing the light diffuser of Comparative Example 1 described later and the resin particles (D) used for producing the light diffuser of Comparative Example 10 will be described.

[Production method of resin particles (C)]
Resin particles (C) were obtained in the same manner as in the method for producing resin particles (A) except that methyl methacrylate was not used and the amount of styrene used was 900 g. The volume average particle size of the resin particles (C) was 5.6 μm as measured by the above measuring method. The CV value of the resin particles (C) was 38.2% when calculated by the above calculation method. Further, the refractive index of the resin particles (C) was 1.592 as measured by the measurement method described above.

[Production Method of Resin Particle (D)]
A stainless steel beaker having a volume of 5 L was charged with 3000 g of pure water, 1.5 g (500 ppm) of sodium lauryl sulfate, and 90 g of magnesium pyrophosphate to prepare an aqueous phase.

  In a stainless steel beaker different from the stainless steel beaker used for the preparation of the aqueous phase, 950 g of methyl methacrylate as a (meth) acrylic monofunctional monomer and 50 g of ethylene glycol dimethacrylate (EGDMA) as a polyfunctional monomer N-dodecyl mercaptan as a chain transfer agent, 7 g of 2,2-azobis- (2,4-dimethylvaleronitrile) as a polymerization initiator, and 4 g of tert-butylperoxy-2-ethylhexanoate Were added and sufficiently stirred to prepare an oil phase.

  The prepared oil phase was added to the previously prepared aqueous phase, and the mixture was stirred at 8000 rpm for 15 minutes using a TK homomixer manufactured by PRIMIX Co., Ltd. to obtain a suspension. The resulting suspension was then transferred to a 5 L reactor equipped with a stirrer and thermometer, and then the monomer was polymerized at 50 ° C. for 5 hours, and then heated at 105 ° C. for 2 hours. After cooling to 30 ° C., a resin particle slurry was obtained. Next, hydrochloric acid was added to the resin particle slurry until the pH of the slurry was 2 or less. Next, the resin particle slurry to which hydrochloric acid was added was washed using a centrifugal dehydrator until the pH of the washing water became 6 to 7, and then dehydrated. The dehydrated cake thus obtained was vacuum-dried at a jacket temperature of 60 ° C. for 20 hours using a vacuum dryer. Next, it passed through a 400-mesh sieve to obtain resin particles (D). The volume average particle diameter of the resin particles (D) was 5.2 μm as measured by the above measuring method. The CV value of the resin particles (D) was 34.2% when calculated by the above calculation method. The refractive index of the resin particles (D) was 1.496 as measured by the measurement method described above.

  Subsequently, the manufacturing method of resin particle (E)-(H) used for manufacture of the light diffusing body of Examples 7-10 of this invention is demonstrated.

[Production Method of Resin Particle (E)]
The amount of methyl methacrylate used as the (meth) acrylic monofunctional monomer is 350 g, the amount of styrene used as the styrene monofunctional monomer is 600 g, and divinylbenzene is used as the polyfunctional monomer. Resin particles (E) were obtained in the same manner as in the method for producing resin particles (A), except that 50 g of ethylene glycol dimethacrylate (EGDMA) was used instead of 100 g of (DVB).

  The volume average particle diameter of the resin particles (E) was 5.5 μm as measured by the above measuring method. The CV value of the resin particles (E) was 37.0% as calculated by the above calculation method. Further, the refractive index of the resin particles (E) was 1.554 as measured by the measurement method described above.

[Production method of resin particles (F)]
The amount of methyl methacrylate used as the (meth) acrylic monofunctional monomer is 350 g, the amount of styrene used as the styrene monofunctional monomer is 600 g, and divinylbenzene is used as the polyfunctional monomer. Resin particles (F) were obtained in the same manner as in the method for producing resin particles (A) except that 50 g of trimethylolpropane trimethacrylate (TMP) was used instead of 100 g of (DVB).

  The volume average particle diameter of the resin particles (F) was 5.4 μm as measured by the above measuring method. The CV value of the resin particles (F) was 36.5% when calculated by the above calculation method. Moreover, the refractive index of this resin particle (F) was 1.553 when measured by the above-mentioned measuring method.

[Production Method of Resin Particle (G)]
The amount of methyl methacrylate used as the (meth) acrylic monofunctional monomer is 350 g, the amount of styrene used as the styrene monofunctional monomer is 600 g, and divinylbenzene is used as the polyfunctional monomer. (DVB) Instead of 100 g, resin particles (G) were prepared in the same manner as in the method for producing resin particles (A) except that 50 g of 1,6-hexanediol dimethacrylate (1,6HX) was used. Obtained.

  The volume average particle diameter of the resin particles (G) was 5.3 μm as measured by the above measuring method. The CV value of the resin particles (G) was 38.9% when calculated by the above calculation method. Further, the refractive index of the resin particles (G) was 1.553 as measured by the measurement method described above.

[Production method of resin particles (H)]
The amount of methyl methacrylate used as the (meth) acrylic monofunctional monomer is 350 g, the amount of styrene used as the styrene monofunctional monomer is 600 g, and divinylbenzene is used as the polyfunctional monomer. (DVB) Instead of 100 g, resin particles (H) were obtained in the same manner as in the method for producing resin particles (A) except that 50 g of allyl methacrylate (AMA) was used.

  The volume average particle diameter of the resin particles (H) was 5.8 μm as measured by the above measuring method. The CV value of the resin particles (H) was 39.4% when calculated by the above calculation method. Further, the refractive index of the resin particles (H) was 1.554 as measured by the measurement method described above.

  Below, the light diffuser which concerns on Examples 1-10 of this invention and Comparative Examples 1-10 is shown.

[Example 1]
100 parts by weight of an acrylic resin (made by Sumitomo Chemical Co., Ltd., trade name “Sumipex (registered trademark) EX”) as a base resin and acrylic rubber particles (made by Mitsubishi Rayon Co., Ltd. (Registered trademark) W-300A ") 2.5 parts by weight, 2.0 parts by weight of resin particles (A) having a refractive index of 1.555 obtained by the above production method, and volume average particles measured by the above measurement method Barium sulfate having a diameter of 0.50 μm (precipitated barium sulfate “B55” manufactured by Sakai Chemical Industry Co., Ltd., CV value 65.9%, specific surface area 4.13 g / m ² ) 2.0 parts by weight (1 weight of resin particles 1 part by weight) was mixed with a Henschel mixer for 15 minutes to obtain a mixture. This mixture was extruded using a single screw extruder ("R50" manufactured by Hoshi Plastic Co., Ltd.) at a temperature of 210 to 260 ° C and a discharge rate of 10 to 25 kg / h, cooled with water, cut with a pelletizer, and pellets A light diffusing resin composition was obtained. Next, the obtained pellet-like light diffusing resin composition was pre-dried at 105 ° C. for 5 hours, and after sufficiently removing water, a T-die extrusion machine (manufactured by Souken Co., Ltd., aperture 30 mm, L / D) = 38, T die width 250 mm, lip 2 mm) was extruded into a plate shape at a temperature of 220 to 260 ° C. to obtain a light diffusion plate (light diffuser) having a thickness of 2 mm. The light diffusing plate thus obtained was cut into a width of 50 mm and a length of 100 mm to evaluate optical characteristics (measurement of total light transmittance and dispersion) and light resistance (measurement of color difference after accelerated exposure test). Went.

  FIG. 1 shows the results of measuring the transmitted light intensity of the light diffusion plate (light diffuser) obtained in Example 1 using an automatic variable angle photometer. The vertical axis represents the relative value of the transmitted light intensity, and a perpendicular is drawn from the plotted point of the graph when this value is 50% to obtain the intersection with the horizontal axis. The value on the horizontal axis is the angle (°), and is called the degree of dispersion (D50). In the measurement result shown in FIG. 1, the degree of dispersion (D50) is 57.3 °. The dispersity (D50) is the arithmetic average of the absolute values of the two left and right values (angle value when the transmitted light intensity is 50%) at the origin of 0 ° on the horizontal axis.

[Example 2]
Barium sulfate having a volume average particle size of 0.50 μm with respect to 100 parts by weight of the base resin (precipitated barium sulfate “B55” manufactured by Sakai Chemical Industry Co., Ltd., CV value 65.9%, specific surface area 4.13 g / m ² ) Instead of 2.0 parts by weight, barium sulfate having a volume average particle diameter of 0.62 μm (precipitated barium sulfate “B300” manufactured by Sakai Chemical Industry Co., Ltd., CV value 59.9%, specific surface area 3.4 g / M ² ) A light diffusion plate (light diffuser) was obtained in the same manner as in Example 1 except that 2.0 parts by weight (1 part by weight with respect to 1 part by weight of the resin particles) was blended.

Example 3
1.5 parts by weight of the resin particles (A) are blended with 100 parts by weight of the base resin, and barium sulfate having a volume average particle size of 0.50 μm (precipitated barium sulfate manufactured by Sakai Chemical Industry Co., Ltd. “ B55 ”, CV value 65.9%, specific surface area 4.13 g / m ² ) 2.0 parts by weight of barium sulfate having a volume average particle diameter of 0.62 μm (sedimentable sulfuric acid manufactured by Sakai Chemical Industry Co., Ltd.) Example 1 except that 2.0 parts by weight of barium “B300”, CV value 59.9%, specific surface area 3.4 g / m ² ) (1.33 parts by weight with respect to 1 part by weight of resin particles) was blended. A light diffusion plate (light diffuser) was obtained by the same method.

Example 4
2.5 parts by weight of resin particles (A) are blended with 100 parts by weight of the base resin, and barium sulfate having a volume average particle diameter of 0.50 μm (precipitated barium sulfate manufactured by Sakai Chemical Industry Co., Ltd. “ B55 ”, CV value 65.9%, specific surface area 4.13 g / m ² ) 2.0 parts by weight of barium sulfate having a volume average particle diameter of 0.62 μm (sedimentable sulfuric acid manufactured by Sakai Chemical Industry Co., Ltd.) Example 1 except that 1.5 parts by weight of barium “B300”, CV value 59.9%, specific surface area 3.4 g / m ² ) (0.6 parts by weight with respect to 1 part by weight of resin particles) was blended A light diffusion plate (light diffuser) was obtained by the same method.

Example 5
Barium sulfate having a volume average particle size of 0.50 μm with respect to 100 parts by weight of the base resin (precipitated barium sulfate “B55” manufactured by Sakai Chemical Industry Co., Ltd., CV value 65.9%, specific surface area 4.13 g / m ² ) Instead of 2.0 parts by weight, barium sulfate having a volume average particle diameter of 0.62 μm (precipitated barium sulfate “B300” manufactured by Sakai Chemical Industry Co., Ltd., CV value 59.9%, specific surface area 3.4 g / M ² ) 2.0 parts by weight (1 part by weight with respect to 1 part by weight of the resin particles) is blended, and acrylic rubber particles (manufactured by Mitsubishi Rayon Co., Ltd., trade name “Metablene (registered trademark) W—” A light diffusing plate (light diffusing body) was obtained in the same manner as in Example 1 except that 300A ") was not blended.

Example 6
In place of 2.0 parts by weight of resin particles (A) with respect to 100 parts by weight of base resin, 2.5 parts by weight of resin particles (B) having a refractive index of 1.540 obtained by the above-described production method are blended A light diffusion plate (light diffuser) was obtained by the same method as in Example 1 except that.

Example 7
In place of 2.0 parts by weight of resin particles (A) with respect to 100 parts by weight of the base resin, 2.0 parts by weight of resin particles (E) having a refractive index of 1.554 obtained by the manufacturing method described above are blended A light diffusion plate (light diffuser) was obtained in the same manner as in Example 5 except that.

Example 8
In place of 2.0 parts by weight of resin particles (A) with respect to 100 parts by weight of base resin, 2.0 parts by weight of resin particles (F) having a refractive index of 1.553 obtained by the above-described production method are blended. A light diffusion plate (light diffuser) was obtained in the same manner as in Example 5 except that.

Example 9
In place of 2.0 parts by weight of resin particles (A) with respect to 100 parts by weight of base resin, 2.0 parts by weight of resin particles (G) having a refractive index of 1.553 obtained by the above-described production method are blended. A light diffusion plate (light diffuser) was obtained in the same manner as in Example 5 except that.

Example 10
In place of 2.0 parts by weight of resin particles (A) with respect to 100 parts by weight of base resin, 2.0 parts by weight of resin particles (H) having a refractive index of 1.554 obtained by the above-described manufacturing method are blended A light diffusion plate (light diffuser) was obtained in the same manner as in Example 5 except that.

[Comparative Example 1]
In place of 2.0 parts by weight of resin particles (A) with respect to 100 parts by weight of the base resin, 2.0 parts by weight of resin particles (C) having a refractive index of 1.592 obtained by the above-described production method are blended Furthermore, barium sulfate having a volume average particle diameter of 0.50 μm (precipitated barium sulfate “B55” manufactured by Sakai Chemical Industry Co., Ltd., CV value 65.9%, specific surface area 4.13 g / m ² ) 2.0 Instead of parts by weight, barium sulfate having a volume average particle diameter of 0.62 μm (precipitated barium sulfate “B300” manufactured by Sakai Chemical Industry Co., Ltd., CV value 59.9%, specific surface area 3.4 g / m ² ) 2 A light diffusion plate (light diffuser) was obtained in the same manner as in Example 1 except that 0.0 part by weight (1 part by weight with respect to 1 part by weight of the resin particles) was blended.

[Comparative Example 2]
0.7 parts by weight of the resin particles (A) are blended with 100 parts by weight of the base resin, and barium sulfate having a volume average particle size of 0.50 μm (precipitated barium sulfate manufactured by Sakai Chemical Industry Co., Ltd. “ B55 ”, CV value 65.9%, specific surface area 4.13 g / m ² ) 2.0 parts by weight of barium sulfate having a volume average particle diameter of 0.62 μm (sedimentable sulfuric acid manufactured by Sakai Chemical Industry Co., Ltd.) Example 1 except that barium “B300”, CV value 59.9%, specific surface area 3.4 g / m ² ) 2.2 parts by weight (3.14 parts by weight with respect to 1 part by weight of resin particles) was blended A light diffusion plate (light diffuser) was obtained by the same method.

[Comparative Example 3]
Barium sulfate having a volume average particle diameter of 0.50 μm (precipitation barium sulfate “B55” manufactured by Sakai Chemical Industry Co., Ltd., CV value 65.9%, specific surface area 4.13 g / m) with respect to 100 parts by weight of the base resin ² ) Instead of 2.0 parts by weight, barium sulfate having a volume average particle diameter of 0.34 μm (precipitated barium sulfate “B30” manufactured by Sakai Chemical Industry Co., Ltd., CV value 89.4%, specific surface area 13.84 g / M ² ) A light diffusion plate (light diffuser) was obtained in the same manner as in Example 1 except that 2.0 parts by weight (1 part by weight with respect to 1 part by weight of the resin particles) was blended.

[Comparative Example 4]
With respect to 100 parts by weight of the base resin, barium sulfate having a volume average particle size of 0.50 μm (precipitated barium sulfate “B55” manufactured by Sakai Chemical Industry Co., Ltd., CV value 65.9%, specific surface area 4.13 g / m ² ) Instead of 2.0 parts by weight, barium sulfate having a volume average particle diameter of 0.62 μm (precipitated barium sulfate “B300” manufactured by Sakai Chemical Industry Co., Ltd., CV value 59.9%, specific surface area 3. 4 g / m ² ) A light diffusion plate (light diffuser) was obtained in the same manner as in Example 1 except that 0.5 part by weight (0.25 part by weight with respect to 1 part by weight of resin particles) was blended. .

[Comparative Example 5]
1 part by weight of resin particles (A) is blended with 100 parts by weight of the base resin, and barium sulfate having a volume average particle size of 0.50 μm (precipitated barium sulfate “B55” manufactured by Sakai Chemical Industry Co., Ltd.) , CV value 65.9%, specific surface area 4.13 g / m ² ) instead of 2.0 parts by weight, barium sulfate having a volume average particle diameter of 0.62 μm (precipitated barium sulfate manufactured by Sakai Chemical Industry Co., Ltd. “ B300 ", CV value 59.9%, specific surface area 3.4 g / m ² ) 4 parts by weight (4 parts by weight with respect to 1 part by weight of resin particles) were used in the same manner as in Example 1 to obtain light. A diffusion plate (light diffuser) was obtained.

[Comparative Example 6]
With respect to 100 parts by weight of the base resin, barium sulfate having a volume average particle size of 0.50 μm (precipitated barium sulfate “B55” manufactured by Sakai Chemical Industry Co., Ltd., CV value 65.9%, specific surface area 4.13 g / A light diffusion plate (light diffuser) was obtained by the same method as in Example 1 except that m ² ) was not blended.

[Comparative Example 7]
3 parts by weight of resin particles (A) are blended with 100 parts by weight of the base resin, and barium sulfate having a volume average particle size of 0.50 μm (precipitated barium sulfate “B55” manufactured by Sakai Chemical Industry Co., Ltd.) And a CV value of 65.9% and a specific surface area of 4.13 g / m ² ), a light diffusion plate (light diffuser) was obtained in the same manner as in Example 1.

[Comparative Example 8]
5 parts by weight of resin particles (A) are blended with 100 parts by weight of the base resin, and barium sulfate having a volume average particle diameter of 0.50 μm (precipitated barium sulfate “B55” manufactured by Sakai Chemical Industry Co., Ltd.) And a CV value of 65.9% and a specific surface area of 4.13 g / m ² ), a light diffusion plate (light diffuser) was obtained in the same manner as in Example 1.

[Comparative Example 9]
With respect to 100 parts by weight of the base resin, barium sulfate having a volume average particle size of 0.50 μm (precipitated barium sulfate “B55” manufactured by Sakai Chemical Industry Co., Ltd., CV value 65.9%, specific surface area 4.13 g / m ² ) Instead of 2.0 parts by weight, barium sulfate having a volume average particle diameter of 0.75 μm (precipitated barium sulfate “B-1” manufactured by Sakai Chemical Industry Co., Ltd., CV value 49.4%, specific surface area 2.2 g / m ² ) A light diffusion plate (light diffuser) was obtained in the same manner as in Example 1 except that 2.0 parts by weight was blended.

[Comparative Example 10]
Instead of 2.0 parts by weight of resin particles (A) with respect to 100 parts by weight of the base resin, 2.0 parts by weight of resin particles (D) having a refractive index of 1.496 obtained by the manufacturing method described above are blended Furthermore, barium sulfate having a volume average particle size of 0.50 μm (precipitated barium sulfate “B55” manufactured by Sakai Chemical Industry Co., Ltd., CV value 65.9%, specific surface area 4.13 g / m ² ) 2.0 weight 1. barium sulfate having a volume average particle size of 0.62 μm (precipitated barium sulfate “B300” manufactured by Sakai Chemical Industry Co., Ltd., CV value 59.9%, specific surface area 3.4 g / m ² ) A light diffusion plate (light diffuser) was obtained in the same manner as in Example 1 except that 0 part by weight (1 part by weight with respect to 1 part by weight of the resin particles) was blended.

  In Table 1, the compounding quantity of the various raw materials of the light diffusable resin composition used for manufacture of the light diffusing material which concerns on Examples 1-10 and Comparative Examples 1-10 (weight part with respect to 100 weight part of base resin), these The total light transmittance of the light diffusing body which concerns on Examples 1-6 and Comparative Examples 1-10, dispersion degree (D50), and the color difference (hunter (DELTA) E value) after an accelerated exposure test are shown.

  As shown in Table 1, the light diffusers of Examples 1 to 10 of the present invention have 55% or more (specifically, 55.44 to 58.30%) when the thickness is 2 mm. A total light transmittance and a degree of dispersion of 55 ° or more (specifically, 55.00 to 57.95 °) were exhibited, and it was recognized that excellent light transmittance and light diffusibility were exhibited. Moreover, the color difference (hunter ΔE value) after 200 hours of accelerated exposure of the light diffusers of Examples 1 to 6 of the present invention is less than 3 (specifically, 2.5 or less). It was confirmed that the light diffuser has practically sufficient light resistance for indoor lighting.

  Moreover, the light diffusing material of Examples 7-10 containing either of the resin particle (E)-(H) manufactured using the (meth) acrylic-ester type polyfunctional monomer as a polyfunctional monomer Compared to the light diffusers of Examples 1-6 comprising resin particles (A) or (B) produced using divinylbenzene (DVB) as the polyfunctional monomer, after 200 hours of accelerated exposure It was confirmed that the color difference (Hunter ΔE value) was small and the light resistance was superior. Specifically, the color difference (hunter ΔE value) after 200 hours of accelerated exposure of the light diffusers of Examples 7 to 10 is less than 1 (specifically, 0.6 or less) and is used only for indoor lighting. In addition, it has practically light resistance for outdoor lighting.

  On the other hand, the light diffuser of Comparative Example 1 produced using resin particles (C) having a refractive index of 1.592 has resin particles (A), (B), and (E) having a refractive index of 1.540 to 1.560. ) To (H), the total light transmittance was low compared to the light diffusers of Examples 1 to 10 produced using any one of (H) to (H), and the light transmittance was inferior. Further, the light diffuser of Comparative Example 1 had a color difference after accelerated exposure exceeding 3, and was inferior in light resistance.

  The light diffusing resin composition has a resin particle content of 0.7 parts by weight with respect to 100 parts by weight of the base resin and a barium sulfate content of 3.1 parts by weight with respect to 1 part by weight of the resin particles. The light diffusing material of Comparative Example 2 made of a product has a resin particle content of 1.5 to 2.5 parts by weight with respect to 100 parts by weight of the base resin, and a barium sulfate content of 1 part by weight of the resin particles. Compared to the light diffusers of Examples 1 to 10 consisting of a light diffusing resin composition which is 0.5 to 1.35 parts by weight (more specifically, 0.6 to 1.33 parts by weight). The total light transmittance and the degree of dispersion were low, and the optical properties were inferior.

  The light diffuser of Comparative Example 3 produced using barium sulfate having a volume average particle size of 0.34 μm has a volume average particle size of 0.4 to 0.7 μm (more specifically, 0.50 Compared to the light diffusers of Examples 1 to 10 produced using (˜0.62 μm) barium sulfate, the total light transmittance was low and the light transmittance was inferior.

  The light diffuser of Comparative Example 4 comprising a light diffusing resin composition having a barium sulfate content of 0.25 parts by weight with respect to 1 part by weight of the resin particles has a barium sulfate content of 1 part by weight of the resin particles. The light diffuser of Examples 1 to 10 comprising a light diffusing resin composition in an amount of 0.5 to 1.35 parts by weight (more specifically, 0.6 to 1.33 parts by weight) In comparison, the degree of dispersion was low and the light diffusibility was poor.

  Further, the comparison is made of a light diffusing resin composition in which the content of the resin particles is 1 part by weight with respect to 100 parts by weight of the base resin and the content of barium sulfate is 4 parts by weight with respect to 1 part by weight of the resin particles. In the light diffuser of Example 5, the content of the resin particles is 1.5 to 2.5 parts by weight with respect to 100 parts by weight of the base resin, and the content of barium sulfate is 0.000 with respect to 1 part by weight of the resin particles. Compared with the light diffuser of Examples 1-10 which consists of a light diffusable resin composition which is 5-1.35 weight part (more specifically, 0.6-1.33 weight part), it is a total light transmission. The rate was low and the light transmission was poor.

  Moreover, the light diffusing bodies of Comparative Examples 6 to 8 made of a light diffusing resin composition not containing barium sulfate were compared with the light diffusing bodies of Examples 1 to 10 made of a light diffusing resin composition containing barium sulfate. Thus, the degree of dispersion was low and the light diffusibility was poor. Further, the light diffusers of Comparative Examples 7 and 8 had a color difference after accelerated exposure of more than 3, and were inferior in light resistance.

  The light diffuser of Comparative Example 9 produced using barium sulfate having a volume average particle size of 0.75 μm has a volume average particle size of 0.4 to 0.7 μm (more specifically, 0.50 Compared to the light diffusers of Examples 1 to 10 produced using (˜0.62 μm) barium sulfate, the degree of dispersion was low and the light diffusibility was poor.

  The light diffuser of Comparative Example 10 produced using the resin particles (D) with a refractive index of 1.496 has resin particles (A), (B), and (E) with a refractive index of 1.540 to 1.560. Compared to the light diffusers of Examples 1 to 10 produced using any of (H), the degree of dispersion was low and the light diffusibility was poor.

The light diffuser according to the present invention is a light diffuser comprising a light diffusing resin composition in which resin particles and an inorganic compound are dispersed in a base resin, and the resin particles are (meth) acrylic single particles. The inorganic compound is a polymer particle having a volume average particle diameter of 2 to 10 μm and a refractive index of 1.540 to 1.560 comprising a polymer of a monomer mixture containing a functional monomer and a polyfunctional monomer. Is a barium sulfate having a volume average particle diameter of 0.4 to 0.7 μm, and the light diffusing resin composition contains 1.5 to 2 parts of the resin particles with respect to 100 parts by weight of the base resin . 5 parts by weight, wherein the content ratio of the resin particles and the inorganic compound in the light diffusing resin composition is in a range of 1: 0.5 to 1: 1.35 by weight. To do. In addition, in this specification, (meth) acryl means methacryl or acryl.

Claims (7)

A light diffuser comprising a light diffusing resin composition in which resin particles and an inorganic compound are dispersed in a base resin,
The resin particles have a volume average particle diameter of 2 to 10 μm and a refractive index of 1.540 to 1 made of a polymer of a monomer mixture containing a (meth) acrylic monofunctional monomer and a polyfunctional monomer. 560 polymer particles,
The inorganic compound is barium sulfate having a volume average particle size of 0.4 to 0.7 μm,
The light diffusing resin composition contains 1.5 to 2.5 parts by weight of the resin particles with respect to 100 parts by weight of the light diffusing resin composition,
The light diffusing body, wherein a content ratio of the resin particles and the inorganic compound in the light diffusing resin composition is in a range of 1: 0.5 to 1: 1.35 by weight. The light diffuser according to claim 1,
The light diffusing body, wherein the polyfunctional monomer is a (meth) acrylic acid ester polyfunctional monomer. The light diffuser according to claim 1 or 2,
The light diffuser, wherein the monomer mixture contains a styrene monofunctional monomer. The light diffuser according to any one of claims 1 to 3,
The light diffuser, wherein the base resin is an acrylic resin. The light diffuser according to any one of claims 1 to 4, wherein
The light diffusing body, wherein the light diffusing resin composition contains a rubber component. The light diffuser according to any one of claims 1 to 5,
A light diffuser characterized in that the light diffuser has a thickness of 1.0 to 3.0 mm. The light diffuser according to any one of claims 1 to 6,
A light diffuser obtained by molding the light diffusing resin composition obtained by mixing the resin particles, the inorganic compound, and the base resin by an extrusion molding method.

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