JP5522957B2 - Polymer particle aggregate, method for producing the same, light diffusing agent, and light diffusing resin composition - Google Patents

Description

  The present invention relates to a polymer particle aggregate, a method for producing the same, a light diffusing agent, and a light diffusing resin composition. The polymer particle aggregate of the present invention can be suitably used as, for example, a light diffusing agent for a lighting cover or a light diffusing agent for a light diffusing plate of a liquid crystal display device.

Conventionally, it has been desired to uniformly diffuse light emitted from a light source of illumination and a backlight of a liquid crystal panel in a light diffusing plate of a lighting cover and a liquid crystal display device. As a method of diffusing light, a method using a so-called embossed light diffusing sheet that gives unevenness to the surface by heating and pressing during finishing processing, or inorganic powder such as titanium oxide, glass beads, silica, etc. There are a method using a light diffusing plate provided with a light diffusing layer containing, a method using a light diffusing plate provided with a light diffusing layer containing (meth) acrylic polymer particles, and the like.
Among these, light diffusion plates using polymer particles are known to be both excellent in transparency and light diffusion and to be excellent light diffusion plates (for example, JP-A-6-32973: Patent Reference 1).

The light diffusion layer is composed of polymer particles and a transparent resin, and the polymer particles used as the light diffusing agent are required to have dispersibility in the transparent resin in addition to the light diffusibility. Furthermore, when a molded body is formed by extrusion molding after mixing with a dispersion medium such as a resin, it is required that no molding occurs on the molded body during processing.
As a technique for examining polymer particles from the viewpoint of dispersibility, for example, there is JP-A-58-74724 (Patent Document 2). This publication describes a technique for forming an aggregate of polymer particles by spray-drying a dispersion in which polymer particles are dispersed in water, and this aggregate has good redispersibility in water. It is said that.
Japanese Patent Laid-Open No. 2000-53720 (Patent Document 3) also describes a technique for forming an aggregate of polymer particles by spray drying.

JP-A-6-32973 JP 58-74724 A JP 2000-53720 A

In the aggregate described in JP-A-58-74724, since the polymer particles constituting the aggregate do not have a cross-linked structure, the heat resistance of the polymer particles is low, and the fusion between the polymer particles during the production of the aggregate There was a problem that is likely to occur. Generation | occurrence | production of melt | fusion will reduce the dispersibility to transparent resin.
Furthermore, the technique disclosed in Japanese Patent Application Laid-Open No. 2000-53720 aims to obtain an aggregate in which high-strength polymer particles are difficult to disperse in order to increase the specific surface area, thereby improving dispersibility of the polymer particles. Therefore, the technical idea of forming an aggregate of polymer particles is not described.

As a result of intensive studies, the inventors of the present invention have obtained a polymer obtained by drying a dispersion containing polymer particles, a surfactant and an inorganic powder by a spray drying method under specific temperature conditions.

The present inventors have found that a particle aggregate can solve the above-mentioned problems and have reached the present invention.
Thus, according to the present invention, a monofunctional monomer selected from styrene monomers and (meth) acrylic monomers, and styrene monomers and (meth) acrylic monomers are selected. Obtaining an aggregate of the polymer particles by spray drying a slurry containing a polymer mixture comprising a monomer mixture containing a polyfunctional monomer, a surfactant, an inorganic powder, and an aqueous medium. Consists of
The polyfunctional monomer is used in an amount of 1 to 100 parts by weight based on 100 weights of the monofunctional monomer,
The surfactant is used in an amount of 1 to 10 parts by weight with respect to 100 parts by weight in total of the monofunctional monomer and the polyfunctional monomer,
The inorganic powder is used in an amount of 1 to 40 parts by weight with respect to a total of 100 parts by weight of the monofunctional monomer and polyfunctional monomer,
The spray drying, the slurry inlet temperature of 80 to 220 ° C. in a spray dryer, conducted under the conditions of collection outlet temperature of 50 to 100 ° C. in a spray drier,
The aggregate of the polymer particles is obtained by irradiating the dispersion containing 0.50 g of the aggregate of polymer particles with 50 g of water for 10 minutes with ultrasonic waves. polymer production method of particle aggregates, wherein the aggregate der Rukoto having a particle size distribution containing particles of more than 90% ± 1 [mu] m of the average particle size of the polymer particles constituting the aggregate is provided.

Further, according to the present invention, there is provided a polymer particle aggregate obtained by the above method, wherein the polymer particle aggregate is 10 in a dispersion containing 0.50 g of the polymer particle aggregate with respect to 50 g of water. The particles in the dispersion after being irradiated with ultrasonic waves for a minute are aggregates having a particle size distribution containing 90% or more of particles having an average particle diameter of ± 1 μm of the polymer particles constituting the polymer particle aggregate. A polymer particle aggregate is provided.
Furthermore, according to this invention, the light-diffusion agent which consists of said polymer particle aggregate is provided.
Furthermore, a light diffusing resin composition comprising 100 parts by weight of a transparent base resin and 0.01 to 40 parts by weight of the light diffusing agent is provided.

According to the production method of the present invention, it is possible to obtain an aggregate of polymer particles whose mutual connection is suppressed. The obtained aggregate is excellent in the dispersibility of the polymer particles in a dispersion medium such as a resin. In addition, since it is not necessary to separately provide a step of crushing the aggregates into the polymer particles, the productivity of the molded body including the polymer particles can be improved, and variations in the performance of the molded body can be suppressed.
When the polyfunctional monomer is ethylene glycol dimethacrylate or divinylbenzene, an aggregate of polymer particles in which mutual coupling is further suppressed can be obtained.
When the inorganic powder is selected from calcium carbonate, colloidal silica, barium sulfate, and titanium oxide, an aggregate of polymer particles in which the mutual connection is further suppressed can be obtained.
Further, since the inorganic powder is a hydrophobic treated inorganic powder, the dispersibility of the polymer particles in the dispersion medium can be further improved when the obtained aggregate is dispersed in a dispersion medium such as a resin. . Further, when the inorganic powder is an inorganic powder that has been subjected to a hydrophobic treatment, high adhesion can be obtained because of the familiarity between the hydrophobic surface and the resin. As a result, it is possible to suppress functional deterioration of the molded body due to environmental changes such as temperature and humidity.
Furthermore, the dispersibility of the polymer particles in the dispersion medium can be further improved by the hydrophobic treated inorganic powder being colloidal silica or titanium oxide subjected to the hydrophobic treatment.
The light diffusing agent of the present invention has good light diffusibility. In addition, processability with a dispersion medium such as a resin is excellent.

  Furthermore, the light diffusing resin composition of the present invention has a high dispersibility of the polymer particles, and has an effect of suppressing the occurrence of scum at the time of extrusion molding to a molded body obtained from this composition. As a result, it is possible to suppress the problem that the appearance of the molded body becomes defective. In addition, the polymer particles in the light diffusing resin composition are desired to have a small particle diameter in order to improve light diffusibility. However, the polymer particles having a small particle size are difficult to handle due to the fact that they are likely to act as dust or have poor fluidity in the composition preparation process. In the present invention, since an aggregate of polymer particles is used, since it is easy to handle and has excellent dispersibility, it is easily dispersed as a primary particle in the transparent resin substrate. Is possible.

It is a schematic explanatory drawing of the measuring method of a spreading | diffusion rate. 2 is an electron micrograph of a polymer particle aggregate of Example 1. FIG.

According to the present invention, a monofunctional monomer selected from styrene monomers and (meth) acrylic monomers, and a polyfunctional monomer selected from styrene monomers and (meth) acrylic monomers. An aggregate of polymer particles (crosslinked particles) by spray-drying a slurry containing polymer particles comprising a monomer mixture containing a functional monomer, a surfactant, an inorganic powder, and an aqueous medium ( Polymer particle aggregate) can be obtained.
(1) Production of polymer particles (Monofunctional monomer)
The monofunctional monomer is selected from styrene monomers and (meth) acrylic monomers. Examples of the styrene monomer include styrene and α-methylstyrene, and examples of the (meth) acrylic monomer include methyl (meth) acrylate, ethyl (meth) acrylate, and butyl (meth) acrylate. Etc. (Meth) acryl means acryl or methacryl.

(Polyfunctional monomer)
The polyfunctional monomer is selected from styrene monomers and (meth) acrylic monomers. Examples of the styrene monomer include divinylbenzene, and examples of the (meth) acrylic monomer include ethylene glycol di (meth) acrylate and trimethylolpropane triacrylate.
The usage-amount of a polyfunctional monomer is the range of 1-100 weight part with respect to 100 weight part of monofunctional monomers. If it is less than 1 part by weight, the heat resistance is insufficient and the polymer particles may be fused during drying. If it exceeds 100 parts by weight, the polymer particles may aggregate during the polymerization and the target polymer particle aggregate may not be obtained. A preferable amount of the polyfunctional monomer is 2 to 60 parts by weight.
(Other monomers)
Other monomers such as vinyl halide monomers and vinylcyan monomers may be added to the monomer mixture.

(Surfactant)
As the surfactant, any of anionic, nonionic, cationic and zwitterionic surfactants can be used.
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.
You may use the said surfactant individually or in combination of 2 or more types.

  The usage-amount of surfactant is 1-10 weight part with respect to a total of 100 weight part of a monofunctional monomer and a polyfunctional monomer. If the amount is less than 1 part by weight, the effect of suppressing fusion between the polymer particles is insufficient, which is not preferable. If the amount exceeds 10 parts by weight, new particles other than the intended polymer particles are generated, which is not preferable. Generation | occurrence | production of a new particle reduces the function as a light-diffusion agent. A more preferable amount of the surfactant used is 1.5 to 8 parts by weight.

(Method for producing polymer particles)
The polymer particles can be produced by a known method such as emulsion polymerization, suspension polymerization, dispersion polymerization or seed polymerization. Among these, seed polymerization and emulsion polymerization in an aqueous medium are preferable, and polymer particles having particularly uniform particle diameters can be obtained by these polymerizations.
As a method for producing polymer particles, for example,
A one-stage polymerization method in which a monomer mixture is dispersed in an aqueous medium and then polymerized;
A two-stage polymerization method in which a monomer is polymerized in an aqueous medium to obtain seed particles, and then the monomer mixture is absorbed by the seed particles and then polymerized.
-The multistage polymerization method etc. which repeat the process of manufacturing the seed particle of a two-stage polymerization method are mentioned. These polymerization methods can be appropriately selected according to the desired average particle diameter of the polymer particles.
The monomer for producing seed particles is not particularly limited, and any of the above monomer for polymer particles can be used.

The aqueous medium is not particularly limited, and examples thereof include water and a mixed medium of water and a water-soluble organic medium (lower alcohol such as methanol and ethanol). In the step of producing seed particles, the aqueous medium is usually used in an amount of 100 to 1000 parts by weight with respect to 100 parts by weight of the monomer for producing seed particles.
Moreover, a polymerization initiator may be used for manufacture of seed particles, and the polymerization initiator that can be used is not particularly limited, and any known polymerization initiator can be used. For example, potassium persulfate, benzoyl peroxide, lauroyl peroxide, bis-3,5,5-trimethylhexanoyl peroxide, t-butylperoxy-2-ethylhexanoate, di-t-butylperoxyhexahydro Peroxides such as terephthalate, t-butylperoxyisobutyrate, azobisisobutyronitrile, azobisisovaleronitrile, 2,2-azobis- (2-methylpropionate), 2,2-azobis An azo such as-(2,4-dimethylvaleronitrile) can be mentioned. The polymerization initiator is usually used in an amount of 0.1 to 5 parts by weight with respect to 100 parts by weight of the monomer for producing seed particles. Moreover, superposition | polymerization at the time of manufacturing a seed particle can be implemented by heating at 50-80 degreeC for 2 to 20 hours.

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

When the surfactant concentration is higher than the critical micelle concentration, if a water-soluble polymerization initiator such as potassium persulfate is used, new particles other than the intended polymer particles may be generated. is there. Therefore, in this case, it is preferable to use an oil-soluble polymerization initiator such as benzoyl peroxide or azobisisovityronitrile.
The polymerization initiator is preferably used in an amount of 0.01 to 10 parts by weight, more preferably 0.01 to 5 parts by weight, with respect to 100 parts by weight of the monomer mixture. When the polymerization initiator is less than 0.01 parts by weight, it is difficult to achieve the function of initiating the polymerization, and when it exceeds 10 parts by weight, it is not preferable because it is not economical.

Next, examples of the aqueous medium for polymerizing the monomer mixture include water or a mixed medium of water and a water-soluble solvent such as alcohol (for example, methanol, ethanol). The amount of the aqueous medium used is usually 100 to 1000 parts by weight with respect to 100 parts by weight of the monomer mixture in order to stabilize the polymer particles.
In order to suppress the generation of emulsified particles in an aqueous system, water-soluble polymerization inhibitors such as nitrites, sulfites, hydroquinones, ascorbic acids, water-soluble vitamin Bs, citric acid, and polyphenols may be used. Good.
Even if the molecular weight is adjusted by a molecular weight regulator (for example, mercaptans such as n-octyl mercaptan and t-dodecyl mercaptan, terpenes such as t-terpinene and dipentene, and halogenated hydrocarbons such as chloroform and carbon tetrachloride). Good.

Furthermore, a suspension stabilizer may be added in order to improve polymerization stability during polymer particle production and to increase the effect of suppressing fusion between polymer particles. For example, phosphates such as calcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, pyrophosphates such as calcium pyrophosphate, magnesium pyrophosphate, aluminum pyrophosphate, zinc pyrophosphate, magnesium carbonate, calcium hydroxide, hydroxide Examples thereof include poorly water-soluble inorganic compounds such as magnesium, aluminum hydroxide, calcium metasilicate, and calcium sulfate, and water-soluble polymers such as polyvinyl alcohol. In addition, since the yellowing degree of the molded object (for example, light diffusing plate) obtained later by use of a suspension stabilizer becomes high and may reduce a total light transmittance, it needs to be careful.
The addition amount of the suspension stabilizer is usually 0.5 to 15 parts by weight with respect to 100 parts by weight of the monomer mixture.

Polymerization is carried out by adding the monomer mixture to the aqueous medium thus prepared.
During the polymerization reaction, it is preferable to stir the aqueous suspension in which the monomer mixture is dispersed as spherical droplets, and the stirring is performed gently enough to prevent, for example, floating of spherical droplets and sedimentation of particles after polymerization. Just do it.
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.
The polymer particles obtained by polymerization preferably have an average particle size in the range of 0.5 to 30 μm from the viewpoint of light diffusibility and dispersibility. If it is less than 0.5 μm, the light diffusibility and the total light transmittance may be reduced. If it is more than 30 μm, it is necessary to add a large amount of polymer particles in order to obtain the light diffusibility, resulting in a large production cost. May be. A more preferable average particle diameter is 0.6 to 10 μm, and 0.7 to 5 μm is particularly preferable.

(Inorganic powder)
The inorganic powder can be added before, during or after the polymerization. Of these, the addition of inorganic powder to the polymerization system may reduce the polymerization stability, so it is most preferable to add it after the polymerization.
As the inorganic powder, for example, barium sulfate, titanium oxide, calcium carbonate, colloidal silica and the like can be used.

Further, the inorganic powder may be an inorganic powder that has been hydrophobized. In particular, it is colloidal silica or titanium oxide that has been hydrophobized from the viewpoint of preventing mutual connection of polymer particles and improving the dispersibility and adhesion of polymer particles in a dispersion medium such as a resin. More preferred.
Furthermore, the hydrophobized inorganic powder can provide a function capable of preventing a decrease in light transmittance at a high temperature to a light diffusing resin composition (for example, a light diffusing plate) using the inorganic powder as a light diffusing agent. .

Examples of hydrophobizing agents that can be used for hydrophobizing colloidal silica include alkylsilazane compounds such as hexamethyldisilazane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane, methyltrimethoxysilane, and butyltrimethoxy. Alkyl alkoxysilane compounds such as silane, chlorosilane compounds such as dimethyldichlorosilane and trimethylchlorosilane, silicone oil, silicone varnish, and the like can be used.
Examples of hydrophobizing agents that can be used for hydrophobizing titanium oxide include siloxanes such as dimethylpolysiloxane, methylhydrogen polysiloxane, and organically modified silicone oil, silane coupling agents, titanate coupling agents, and aluminum cups. Examples thereof include coupling agents such as ring agents and fluorine-based coupling agents, higher fatty acids, higher alcohols, and amines having a higher alkyl group. In addition, before hydrophobizing the titanium oxide, its surface is coated with an oxide or hydrous oxide such as aluminum, silicon, zirconium, titanium, zinc, tin, etc., thereby improving the affinity with the hydrophobizing agent. May be.

  The average particle diameter of the inorganic powder is preferably in the range of 0.01 to 6 μm. When the average particle size is less than 0.01 μm and exceeds 6 μm, the effect of suppressing fusion of the polymer particles may be reduced. A more preferable average particle diameter is in the range of 0.01 to 5 μm, and a further preferable average particle diameter is in the range of 0.02 to 2 μm.

  The usage-amount of inorganic powder is 1-40 weight part with respect to a total of 100 weight part of a monofunctional monomer and a polyfunctional monomer. If it is less than 1 part by weight, the effect of suppressing fusion between the polymer particles may be insufficient. If it exceeds 40 parts by weight, the effect of suppressing fusion can be obtained, but the function as a light diffusing agent may be lowered. A more preferable usage amount is 1 to 30 parts by weight, and a particularly preferable usage amount is 2 to 20 parts by weight.

In addition, the inorganic powder and the surfactant are preferably in a weight ratio of 1: 0.1 to 2, from the viewpoint of achieving both aggregate retention and polymer particle dispersibility. More preferably, the weight ratio is .5.
As a dispersion method of the inorganic powder in the dispersion, for example, a method of dispersing by a stirring force such as a propeller blade, a method using a homomixer which is a disperser using a high shear force composed of a rotor and a stator, or ultrasonic dispersion And a method of dispersing using a machine.

(2) Production of aggregate of polymer particles The aggregate of polymer particles can be obtained by spray drying the slurry.
(Spray-type drying method)
The spray-type drying method is a method of obtaining dried particles by spraying a slurry together with a gas stream, generally using a spray dryer or a stream dryer. The particle diameter, particle shape, and the like can be adjusted by appropriately adjusting the supply speed of the slurry and gas flow, the drying temperature, the atomizer rotational speed, and the like. Spray drying is performed under conditions where the slurry inlet temperature of the spray dryer is in the range of 80 to 220 ° C and the assembly outlet temperature of the spray dryer is in the range of 50 to 100 ° C. When the slurry inlet temperature is higher than 220 ° C., fusion between the polymer particles is promoted to form an aggregate in which the polymer particles are connected to each other. When the slurry inlet temperature is less than 80 ° C., drying tends to be insufficient, and drying efficiency may be lowered. Further, when the aggregate outlet temperature is less than 50 ° C., drying may be insufficient. On the other hand, when the temperature is higher than 100 ° C., the polymer particles may be fused. A more preferable slurry inlet temperature is 90 to 200 ° C, and an aggregate outlet temperature is 55 to 95 ° C.
Furthermore, the slurry inlet temperature is preferably higher than the aggregate outlet temperature from the viewpoint of preventing fusion between the polymer particles, and is preferably higher than the aggregate outlet temperature in the range of 30 to 120 ° C.

(Aggregation)
The aggregate is composed of a plurality of polymer particles whose mutual connection (fusion) is suppressed. For this reason, the dispersibility of the polymer particles is excellent because they are easy to handle and are easily separated into polymer particles if the aggregate is dispersed in a dispersion medium such as a transparent resin.
The degree of suppression of mutual connection can be evaluated by the particle size distribution measured by the following method. That is, first, the average particle diameter of the polymer particles before forming the aggregate is measured. Next, a dispersion liquid containing 0.50 g of polymer particle aggregate with respect to 50 g of water is prepared. This dispersion is irradiated with ultrasonic waves for 10 minutes. The particle size distribution of the particles in the dispersion after irradiation is measured. In the obtained particle size distribution, the ratio of the particles having the average particle diameter of ± 1 μm is calculated. If the calculation result is 90% or more, it is assumed in the present specification that the polymer particles are aggregates in which the mutual connection is suppressed. A more desirable ratio is 95% or more.

The shape of the aggregate is not particularly limited, and includes a spherical shape, a substantially spherical shape, an indefinite shape, and the like. From the viewpoint of dispersibility in a dispersion medium, a spherical shape or a substantially spherical shape is preferable.
The average particle diameter of the aggregate is preferably 2 to 250 μm. It is practically difficult to obtain an aggregate of less than 2 μm. If it exceeds 250 μm, the efficiency of obtaining an aggregate by spray drying may deteriorate. A more preferable average particle size of the aggregate is 5 to 100 μm.
(Use of aggregate)
The aggregate can be used as a light diffusing agent for lighting covers, a light diffusing agent for light diffusing plates of liquid crystal display devices, a light diffusing agent for cosmetics, a light diffusing agent for paints, and the like. Among these, it is preferable to use for the light diffusing agent for illumination covers, and the light diffusing agent of the light diffusing plate of a liquid crystal display device.

(3) Light diffusing resin composition The light diffusing agent of the present invention is dispersed in a transparent base resin (transparent resin), so that it is a raw material for optical members such as lighting covers and light diffusing plates of liquid crystal display devices. It can be used as (light diffusing resin composition).
As the transparent substrate resin, a thermoplastic resin is usually used. Examples of the thermoplastic resin include (meth) acrylic resin, (meth) acrylic acid alkyl-styrene copolymer, polycarbonate, polyester, polyethylene, polypropylene, Examples include polystyrene. Among these, when excellent transparency is required, (meth) acrylic resin, (meth) acrylic acid acrylic-styrene copolymer, polycarbonate, polyester, and polystyrene are preferable. These thermoplastic resins can be used alone or in combination of two or more.

The addition ratio of the aggregate to the transparent base resin is preferably 0.01 to 40 parts by weight with respect to 100 parts by weight of the transparent base resin. If it is less than 0.01 parts by weight, it may be difficult to give light diffusibility. When the amount is more than 40 parts by weight, light diffusibility can be obtained, but light transmittance may be lowered. A more preferable addition ratio is 0.1 to 10 parts by weight.
The method for forming the light diffusing resin composition is not particularly limited, and the light diffusing agent and the transparent base resin can be formed by conventional methods and conditions such as a mechanical pulverization and mixing method. For example, a Henschel mixer, V-type It can be formed by mixing and stirring the light diffusing agent and the transparent base resin using a mixer, turbula mixer, hybridizer, rocking mixer, or the like.

A light diffusing resin molded sheet can be produced by molding the light diffusing resin composition. In this case, the light diffusing agent and the transparent base resin are mixed with a mixer and kneaded with a melt kneader such as an extruder to obtain a pellet made of the light diffusing resin composition, and the pellet is extruded or melted. By performing post-injection molding, a light diffusion resin molded sheet (optical sheet) having an arbitrary shape can be obtained.
The optical sheet can be used for, for example, a light diffusion plate of a liquid crystal display device. The configuration of the liquid crystal display device is not particularly limited as long as it includes an optical sheet. For example, the liquid crystal display device includes at least a liquid crystal display panel having a display surface and a back surface, a light guide plate disposed on the back surface side of the panel, and a light source that makes light incident on a side surface of the light guide plate. In addition, a reflection sheet is provided on the side of the light guide plate opposite to the surface facing the liquid crystal display panel. This arrangement of light sources is generally referred to as an edge light type backlight arrangement.
Further, in addition to the edge light type backlight arrangement, there is a direct type backlight arrangement. Specifically, this arrangement is an arrangement in which a light source is arranged on the back side of the liquid crystal display panel and at least a light diffusing plate arranged between the liquid crystal display panel and the light source.

EXAMPLES Hereinafter, although this invention is demonstrated using an Example, this invention is not limited by this. In addition, the measuring method of an average particle diameter, evaluation of fusibility, evaluation of the presence or absence of a scum, evaluation of dispersibility, measuring method of total light transmittance, haze, and diffusivity are described below.
(Average particle diameter of polymer particles)
The average particle diameter of the polymer particles is measured with an LS230 type manufactured by Beckman Coulter. Specifically, 0.1 g of particles and 10 ml of a 0.1% nonionic surfactant solution are put into a test tube and mixed for 2 seconds with a touch mixer TOUCHMIXER MT-31 manufactured by Yamato Kagaku. Thereafter, the mixed solution in the test tube is dispersed for 10 minutes using a commercially available ultrasonic cleaner, ULTRASONIC CLEANER VS-150, manufactured by Velvo Crea. The particle size is measured while irradiating ultrasonic waves with the LS230 type manufactured by Beckman Coulter, Inc. The optical model at that time matches the refractive index of the produced particles. The average value of the particle diameter of 0.1 g of particles is the average particle diameter.

(Average particle diameter of polymer particle aggregate)
The electrolyte solution is filled in pores having a pore diameter of 50 to 400 μm, the volume is obtained from the change in conductivity of the electrolyte solution when the polymer particle aggregate passes through the electrolyte solution, and the average particle diameter is calculated. Specifically, the measured average particle diameter is a volume average particle diameter measured by a Coulter Multisizer II manufactured by Beckman Coulter. In the measurement, according to REFERENCE MANUAL FOR THE COULTER MULTISIZER (1987) published by Coulter Electronics Limited, calibration is performed using an aperture suitable for the particle size of the aggregate to be measured.

Specifically, 0.1 g of particles and 10 ml of a 0.1% nonionic surfactant solution are put into a commercially available glass test tube, mixed for 2 seconds with a touch mixer TOUCHMIXERMT-31 manufactured by Yamato Scientific Co., Ltd. In a beaker filled with ISOTON2 (manufactured by Beckman Coulter, Inc .: electrolyte for measurement) equipped with a main body, drop with a dropper while gently stirring to adjust the concentration meter reading on the main body screen to about 10%. Next, aperture size, Current, Gain, Polarity are added to Multisizer 2 body. REFERENCE MANUAL FOR THE issued by Coulter Electronics Limited.
Input according to COULTER MULTISIZER (1987) and measured manually. During the measurement, the beaker is gently stirred to the extent that bubbles do not enter, and the measurement is terminated when 100,000 aggregates are measured.

(Non-fusion)
A dispersion is obtained by using 50 g of water of 0.50 g of an aggregate of polymer particles whose average particle diameter has been measured in advance by the method using the LS230 type. The dispersion is irradiated with ultrasonic waves for 10 minutes using an ultrasonic disperser BRANSON SONIFIER 450 (manufactured by BRANSON: output 450 W, frequency 20 kHz). The particle size in the dispersion after irradiation is measured by the method using the LS230 type to obtain a particle size distribution. The proportion (unfused rate) of particles having a mean particle diameter of ± 1 μm of the polymer particles measured in advance in the particle size distribution is calculated. A case where this ratio is 90% or more is evaluated as ◯ (good non-fusibility), and a case where it is less than 90% is determined as x (non-fusible).

(Mayani occurrence)
The presence or absence of the occurrence of the mean is determined by visual observation of the mean that has accumulated at the die exit of the extruder during pellet production. When there is a mess and the state where it hangs down is confirmed, there is a mess, and when it is not confirmed, there is no mess.

(Total light transmittance, haze, dispersibility)
The total light transmittance is measured according to JIS K 7361. Specifically, the measurement is performed using NHD-2000 manufactured by Nippon Denshoku Industries Co., Ltd.
Haze is measured according to JIS K 7136. Specifically, the measurement is performed using NHD-2000 manufactured by Nippon Denshoku Industries Co., Ltd.
The total light transmittance and haze are values obtained by calculating the average value of the number of measurement samples n = 10. Further, the standard deviation (σ) of the measurement data was calculated and the variation was evaluated.
Dispersibility is indirectly evaluated. That is, when the polymer particle aggregate is not sufficiently dispersed in the base resin, the total light transmittance is high and the haze is low (because the number of particles involved in diffusion is apparently reduced). Therefore, whether the dispersibility is good or bad is judged from the change in this value. Specifically, the case where the total light transmittance is high and the haze is low is designated as dispersibility x, and the case where the total light transmittance is low and the haze is high is designated as dispersibility ○.
100 parts by weight of the transparent base resin and 1 part by weight of the produced polymer particle aggregate were melted and kneaded at 230 ° C. in an extruder, and then pelletized, and this was molded into an injection molding machine (cylinder temperature 230 ° C., residence) The molded product having a thickness of 2 mm and a size of 50 mm × 100 mm is obtained. The total light transmittance, haze, and dispersibility of this are measured according to the following method.

(Diffusion rate)
As shown in FIG. 1, the diffusivity is measured from the normal direction (a) to the light (Li) using the automatic variable angle photometer GONIOPHOTOMETER GP-200 type (manufactured by Murakami Color Research Laboratory Co., Ltd.). Intensity (I5) of transmitted light (L5) at an angle of 5 ° with respect to the normal direction (a) and transmitted light (L20) at an angle of 20 ° ) Intensity (I20) and the intensity (I70) of transmitted light (L70) at an angle of 70 ° are respectively measured and determined by the following equations (1) and (2).
Bθ = Iθ / cos θ (1)
(In the formula, θ is 5 °, 20 ° or 70 ° which is an angle with respect to the normal direction, Bθ is the luminance in the direction of angle θ, and Iθ is the intensity of transmitted light to angle θ)
Diffusion rate = (B20 + B70) × 100 / (2 × B5) (2)
When the diffusivity is low, the effect of concealing the lamp image is low, resulting in uneven brightness. Therefore, a high diffusivity is demanded as a light diffusing agent with a low addition amount.

Example 1
[Manufacture of seed particles]
A polymerization vessel equipped with a stirrer and a thermometer was charged with 1000 g of deionized water, charged with 200 g of methyl methacrylate and 6 g of t-dodecyl mercaptan, and heated to 70 ° C. while purging with nitrogen under stirring. The internal temperature was kept at 70 ° C., 20 g of deionized water in which 1 g of potassium persulfate was dissolved was added as a polymerization initiator, and then polymerization was performed for 10 hours. The average particle diameter of the polymer particles in the obtained emulsion was 0.44 μm.

[Production of polymer particles]
A polymerization vessel equipped with a stirrer and a thermometer was charged with 800 g of deionized water in which 3 g of polyoxyethylene tridecyl ether ammonium sulfate was dissolved, 160 g of butyl acrylate and 40 g of ethylene glycol dimethacrylate as a monomer mixture, and a polymerization initiator. As a mixture, 1 g of azobisisobutyronitrile was added. Then, the mixed solution was T.P. A dispersion was obtained by stirring with K homomixer (made by Tokushu Kika Kogyo Co., Ltd.).

  Furthermore, 60 g of the above emulsion containing seed particles was added to the dispersion, and the mixture was stirred at 30 ° C. for 1 hour to absorb the monomer mixture in the seed particles. Next, the absorbed monomer mixture was polymerized by heating at 50 ° C. for 5 hours under a nitrogen stream, and then cooled to room temperature (about 25 ° C.) to obtain a slurry containing polymer particles. The average particle diameter of the obtained polymer particles was 1.2 μm. After cooling, 50 g of Snowtex O-40 (manufactured by Nissan Chemical Industries, Ltd .: colloidal silica (inorganic powder), solid content 40%, particle size: 0.02-0.03 μm) was added to the resulting slurry. The mixture was stirred for 10 minutes using a K homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.).

[Production of polymer particle aggregate]
The slurry was spray-dried under the following conditions with a spray dryer (model: atomizer take-up system, model number: TRS-3WK) manufactured by Sakamoto Giken Co., Ltd. as a spray dryer to obtain polymer particle aggregates. The average particle size of the polymer particle aggregate was 30 μm.
Supply speed: 25 ml / min
Atomizer speed: 11000 rpm
Air volume: 2m ³ / min
Slurry inlet temperature of spray dryer: 130 ° C
Polymer particle assembly outlet temperature: 70 ° C.
An electron microscope (SEM) photograph of the resulting polymer particle assembly is shown in FIG. As a result of observation, the polymer particle aggregate retained a spherical shape, and mutual connection due to fusion of the polymer particles was not confirmed. The non-fusibility of the polymer particle aggregate was evaluated, and the results are shown in Table 1.

[Manufacture of molded products]
As a transparent base resin, 100 parts by weight of polystyrene (Toyostyrene GP G200C, manufactured by Toyo Styrene Co., Ltd.) and 1 part by weight of the polymer particle aggregate were melted and kneaded at 230 ° C. in an extruder, and then pelletized. did. There was no occurrence of spears during pelletization. The obtained pellets were molded by an injection molding machine (cylinder temperature 230 ° C., residence time 10 minutes) to obtain a molded body of 2 mm thickness and 50 mm × 100 mm.
The total light transmittance, haze, and diffusivity of the obtained molded product were measured, the dispersibility was evaluated, and the results are shown in Table 1.

Example 2
[Manufacture of seed particles]
Seed particles were obtained under the same conditions as in Example 1.
[Production of polymer particles]
The amount of the emulsion containing seed particles was changed to 40 g, 120 g of butyl acrylate and 80 g of ethylene glycol dimethacrylate were used as the monomer mixture, and Luminous (manufactured by Maruo Calcium Co., Ltd .: calcium carbonate, particle size: 0) was used as the inorganic powder. .1 μm) Polymer particles were produced in the same manner as in Example 1 except that 20 g was used. The average particle diameter of the obtained polymer particles was 1.4 μm.

[Production of polymer particle aggregate]
Polymer particle aggregates were obtained under the same conditions as in Example 1. The obtained polymer particle aggregate retained a spherical shape, and mutual connection due to fusion of the polymer particles was not confirmed. The average particle size of the polymer particle aggregate was 33 μm. The non-fusibility of the polymer particle aggregate was evaluated, and the results are shown in Table 1.

[Manufacture of molded products]
A molded body was produced under the same conditions as in Example 1 except that the polymer particle aggregate was used. In addition, no occurrence of scum was observed during pelletization.
The total light transmittance, haze, and diffusivity of the obtained molded product were measured, the dispersibility was evaluated, and the results are shown in Table 1.

Example 3
[Manufacture of seed particles]
Seed particles were obtained under the same conditions as in Example 1.
[Production of polymer particles]
Polymer particles were produced in the same manner as in Example 1 except that the amount of polyoxyethylene tridecyl ether ammonium sulfate used was changed to 6 g and 190 g of styrene and 10 g of ethylene glycol dimethacrylate were used as the monomer mixture. The average particle diameter of the obtained polymer particles was 1.2 μm.

[Production of polymer particle aggregate]
Polymer particle aggregates were obtained under the same conditions as in Example 1. The obtained polymer particle aggregate retained a spherical shape, and mutual connection due to fusion of the polymer particles was not confirmed. The average particle size of the polymer particle aggregate was 30 μm. The non-fusibility of the polymer particle aggregate was evaluated, and the results are shown in Table 1.

[Manufacture of molded products]
A molded body was produced under the same conditions as in Example 1 except that the polymer particle assembly was used and polymethyl methacrylate (Sumipex EXA, manufactured by Sumitomo Chemical Co., Ltd.) was used as the transparent base resin. In addition, no occurrence of scum was observed during pelletization.
The total light transmittance, haze, and diffusivity of the obtained molded product were measured, the dispersibility was evaluated, and the results are shown in Table 1.

Example 4
[Manufacture of seed particles]
Seed particles were obtained under the same conditions as in Example 1.
[Production of polymer particles]
16 g of sodium dodecylbenzenesulfonate was used as a surfactant, 190 g of styrene and 10 g of divinylbenzene as a monomer mixture, and 40 g of Variace B-55 (manufactured by Sakai Chemical Co., Ltd .: barium sulfate, particle size: 0.6 μm) as an inorganic powder. Polymer particles were produced in the same manner as in Example 1 except that was used. The average particle diameter of the obtained polymer particles was 1.2 μm.

[Production of polymer particle aggregate]
Polymer particle aggregates were obtained under the same conditions as in Example 1. The obtained polymer particle aggregate retained a spherical shape, and mutual connection due to fusion of the polymer particles was not confirmed. The average particle size of the polymer particle aggregate was 30 μm. The non-fusibility of the polymer particle aggregate was evaluated, and the results are shown in Table 1.

[Manufacture of molded products]
A molded body was produced under the same conditions as in Example 1 except that the polymer particle assembly was used and polymethyl methacrylate (Sumipex EXA, manufactured by Sumitomo Chemical Co., Ltd.) was used as the transparent base resin. In addition, no occurrence of scum was observed during pelletization.
The total light transmittance, haze, and diffusivity of the obtained molded product were measured, the dispersibility was evaluated, and the results are shown in Table 1.

Example 5
[Manufacture of seed particles]
Seed particles were obtained under the same conditions as in Example 1.
[Production of polymer particles]
As a surfactant, 6 g of sodium dodecylbenzenesulfonate is used, 190 g of styrene and 10 g of ethylene glycol dimethacrylate as a monomer mixture, FTR-700 as an inorganic powder (manufactured by Sakai Chemical Industry Co., Ltd .: titanium oxide, particle size: 0.2 μm) ) Polymer particles were produced in the same manner as in Example 1 except that 2 g was used. The average particle diameter of the obtained polymer particles was 1.2 μm.

[Production of polymer particle aggregate]
Polymer particle aggregates were obtained under the same conditions as in Example 1. The obtained polymer particle aggregate retained a spherical shape, and mutual connection due to fusion of the polymer particles was not confirmed. The average particle size of the polymer particle aggregate was 30 μm. The non-fusibility of the polymer particle aggregate was evaluated, and the results are shown in Table 1.

[Manufacture of molded products]
A molded body was produced under the same conditions as in Example 1 except that the polymer particle assembly was used and polymethyl methacrylate (Sumipex EXA, manufactured by Sumitomo Chemical Co., Ltd.) was used as the transparent base resin. In addition, no occurrence of scum was observed during pelletization.
The total light transmittance, haze, and diffusivity of the obtained molded product were measured, the dispersibility was evaluated, and the results are shown in Table 1.

Example 6
[Manufacture of seed particles]
Seed particles were obtained under the same conditions as in Example 1.
[Production of polymer particles]
Polymer particles were produced in the same manner as in Example 2.

[Production of polymer particle aggregate]
A polymer particle aggregate was obtained under the same conditions as in Example 1 except that the slurry inlet temperature of the spray dryer was 160 ° C. and the polymer particle aggregate outlet temperature was 85 ° C. The obtained polymer particle aggregate retained a spherical shape, and mutual connection due to fusion of the polymer particles was not confirmed. The average particle size of the polymer particle aggregate was 33 μm. The non-fusibility of the polymer particle aggregate was evaluated, and the results are shown in Table 1.

[Manufacture of molded products]
A molded body was produced under the same conditions as in Example 1 except that the polymer particle aggregate was used. In addition, no occurrence of scum was observed during pelletization.
The total light transmittance, haze, and diffusivity of the obtained molded product were measured, the dispersibility was evaluated, and the results are shown in Table 1.

Example 7
[Manufacture of seed particles]
Seed particles were obtained under the same conditions as in Example 1.
[Production of polymer particles]
Polymer particles were produced in the same manner as in Example 1 except that 190 g of styrene and 10 g of ethylene glycol dimethacrylate were used as the monomer mixture. The average particle diameter of the obtained polymer particles was 1.1 μm.

[Production of polymer particle aggregate]
Polymer particle aggregates were obtained under the same conditions as in Example 1. The obtained polymer particle aggregate retained a spherical shape, and mutual connection due to fusion of the polymer particles was not confirmed. The average particle diameter of the polymer particle aggregate was 31 μm. The non-fusibility of the polymer particle aggregate was evaluated, and the results are shown in Table 1.

[Manufacture of molded products]
A molded body was produced under the same conditions as in Example 1 except that the polymer particle aggregate was used and polypropylene (Noblen D101, manufactured by Sumitomo Chemical Co., Ltd.) was used as the transparent base resin. In addition, no occurrence of scum was observed during pelletization.
The total light transmittance, haze, and diffusivity of the obtained molded product were measured, the dispersibility was evaluated, and the results are shown in Table 1.

Example 8
[Manufacture of seed particles]
A polymerization vessel equipped with a stirrer and a thermometer was charged with 2000 g of deionized water, charged with 400 g of methyl methacrylate prepared in advance and 12 g of t-dodecyl mercaptan, and heated to 70 ° C. while purging with nitrogen under stirring. did. The internal temperature was kept at 70 ° C., and 30 g of deionized water in which 2 g of potassium persulfate was dissolved was added as a polymerization initiator, and then polymerization was performed for 12 hours. The average particle size of the polymer particles in the obtained emulsion was 0.45 μm.

[Production of polymer particles]
40 g of emulsion containing seed particles, 4 g of sodium dodecylbenzenesulfonate, 120 g of butyl acrylate, 80 g of ethylene glycol dimethacrylate, and TTO-S-2 (made by Ishihara Sangyo Co., Ltd .: Hydrophobized with higher fatty acids as inorganic powder) Polymer particles were produced in the same manner as in Example 1 except that 15 g of treated titanium oxide, particle diameter: minor axis 0.01 to 0.02 μm, major axis 0.05 to 0.1 μm) were used. . The obtained polymer particles had an average particle size of 1.4 μm.

[Production of polymer particle aggregate]
Polymer particle aggregates were obtained under the same conditions as in Example 1 except that the atomizer speed was changed to 13000 rpm. The obtained polymer particle aggregate retained a spherical shape, and mutual connection due to fusion of the polymer particles was not confirmed. The average particle diameter of the polymer particle aggregate was 28 μm. The non-fusibility of the polymer particle aggregate was evaluated, and the results are shown in Table 1.

[Manufacture of molded products]
A molded body was produced under the same conditions as in Example 1 except that the polymer particle aggregate was used. In addition, no occurrence of scum was observed during pelletization.
The total light transmittance, haze, and diffusivity of the obtained molded product were measured, the dispersibility was evaluated, and the results are shown in Table 1.

Example 9
[Manufacture of seed particles]
Seed particles were obtained under the same conditions as in Example 8.
[Production of polymer particles]
40 g of emulsion containing seed particles, 4 g of sodium dodecylbenzenesulfonate, 140 g of butyl acrylate, and 60 g of ethylene glycol dimethacrylate were used, and SYLOPHOBIC507 (Fuji Silysia Co., Ltd .: hydrophobized with an organosilicon compound as an inorganic powder was used. Polymer particles were produced in the same manner as in Example 1 except that 30 g of colloidal silica (particle diameter: 2.7 μm) was used. The average particle diameter of the obtained polymer particles was 1.4 μm.

[Production of polymer particle aggregate]
Polymer particle aggregates were obtained under the same conditions as in Example 1 except that the atomizer speed was changed to 13000 rpm. The obtained polymer particle aggregate retained a spherical shape, and mutual connection due to fusion of the polymer particles was not confirmed. The average particle size of the polymer particle aggregate was 27 μm. The non-fusibility of the polymer particle aggregate was evaluated, and the results are shown in Table 1.

[Manufacture of molded products]
A molded body was produced under the same conditions as in Example 1 except that the polymer particle aggregate was used. In addition, no occurrence of scum was observed during pelletization.
The total light transmittance, haze, and diffusivity of the obtained molded product were measured, the dispersibility was evaluated, and the results are shown in Table 1.

Example 10
[Manufacture of seed particles]
Seed particles were obtained under the same conditions as in Example 8.
[Production of polymer particles]
60 g of emulsion containing seed particles, 190 g of styrene and 10 g of ethylene glycol dimethacrylate are used, and SYLOPHOBIC507 as an inorganic powder (manufactured by Fuji Silysia: colloidal silica hydrophobized with an organosilicon compound, particle size: 2.7 μm) Polymer particles were produced in the same manner as in Example 1 except that 16 g of was used. The average particle diameter of the obtained polymer particles was 1.2 μm.

[Production of polymer particle aggregate]
Polymer particle aggregates were obtained under the same conditions as in Example 1 except that the atomizer speed was changed to 13000 rpm. The obtained polymer particle aggregate retained a spherical shape, and mutual connection due to fusion of the polymer particles was not confirmed. The average particle size of the polymer particle aggregate was 27 μm. The non-fusibility of the polymer particle aggregate was evaluated, and the results are shown in Table 1.

[Manufacture of molded products]
A molded body was produced under the same conditions as in Example 1 except that the polymer particle aggregate was used and polypropylene (Noblen D101, manufactured by Sumitomo Chemical Co., Ltd.) was used as the transparent base resin. In addition, no occurrence of scum was observed during pelletization.
The total light transmittance, haze, and diffusivity of the obtained molded product were measured, the dispersibility was evaluated, and the results are shown in Table 1.

Comparative Example 1
[Manufacture of seed particles]
Seed particles were obtained under the same conditions as in Example 1.
[Production of polymer particles]
The amount of the emulsion containing the seed particles was changed to 40 g, 6 g of sodium dodecylbenzenesulfonate was used as the surfactant, 160 g of butyl acrylate and 40 g of ethylene glycol dimethacrylate as the monomer mixture, and Snowtex O as the inorganic powder. Polymer particles were produced in the same manner as in Example 1 except that 2.5 g of -40 (manufactured by Nissan Chemical Industries, Ltd .: colloidal silica (pure content 40%)) was used. The average particle diameter of the obtained polymer particles was 1.4 μm.

[Production of polymer particle aggregate]
Polymer particle aggregates were obtained under the same conditions as in Example 1. Although the obtained polymer particle aggregate had a spherical shape, mutual connection due to fusion of the polymer particles was confirmed. The average particle size of the polymer particle aggregate was 35 μm. The non-fusibility of the polymer particle aggregate was evaluated, and the results are shown in Table 1.

[Manufacture of molded products]
A molded body was produced under the same conditions as in Example 1 except that the polymer particle aggregate was used. However, generation of scallions was observed during pelletization.
The total light transmittance, haze, and diffusivity of the obtained molded product were measured, the dispersibility was evaluated, and the results are shown in Table 1.

Comparative Example 2
[Manufacture of seed particles]
Seed particles were obtained under the same conditions as in Example 1.
[Production of polymer particles]
The same amount as in Example 1 except that the amount of the surfactant used was changed to 10 g, 190 g of styrene and 10 g of divinylbenzene were used as the monomer mixture, and 100 g of Luminous (manufactured by Maruo Calcium Co .: calcium carbonate) was used as the inorganic powder. Thus, polymer particles were produced. The average particle diameter of the obtained polymer particles was 1.1 μm.

[Production of polymer particle aggregate]
Polymer particle aggregates were obtained under the same conditions as in Example 1. The obtained polymer particle aggregate retained a spherical shape, and mutual connection due to fusion of the polymer particles was not confirmed. The average particle size of the polymer particle aggregate was 30 μm. The non-fusibility of the polymer particle aggregate was evaluated, and the results are shown in Table 1.

[Manufacture of molded products]
A molded body was produced under the same conditions as in Example 1 except that the polymer particle assembly was used and polymethyl methacrylate (Sumipex EXA, manufactured by Sumitomo Chemical Co., Ltd.) was used as the transparent base resin. In addition, no occurrence of scum was observed during pelletization.
The total light transmittance, haze, and diffusivity of the obtained molded product were measured, the dispersibility was evaluated, and the results are shown in Table 1.

Comparative Example 3
[Manufacture of seed particles]
Seed particles were obtained under the same conditions as in Example 1.
[Production of polymer particles]
The amount of the surfactant used was changed to 0.6 g, except that 150 g of butyl acrylate and 50 g of ethylene glycol dimethacrylate were used as the monomer mixture, and 20 g of Luminous (manufactured by Maruo Calcium Co., Ltd .: calcium carbonate) was used as the inorganic powder. In the same manner as in Example 1, polymer particles were produced. The obtained polymer particles had an average particle size of 1.1 μm, and as a result of observation with an electron microscope, generation of new particles was confirmed.

[Production of polymer particle aggregate]
Polymer particle aggregates were obtained under the same conditions as in Example 1. The obtained polymer particle aggregate retained a spherical shape, and mutual connection due to fusion of the polymer particles was confirmed. The average particle diameter of the polymer particle aggregate was 31 μm. The non-fusibility of the polymer particle aggregate was evaluated, and the results are shown in Table 1.

[Manufacture of molded products]
A molded body was produced under the same conditions as in Example 1 except that the polymer particle aggregate was used. In addition, no occurrence of scum was observed during pelletization.
The total light transmittance, haze, and diffusivity of the obtained molded product were measured, the dispersibility was evaluated, and the results are shown in Table 1.

Comparative Example 4
[Manufacture of seed particles]
Seed particles were obtained under the same conditions as in Example 1.
[Production of polymer particles]
Polymer particles were produced in the same manner as in Example 1 except that the amount of the surfactant used was changed to 22 g and 190 g of styrene and 10 g of divinylbenzene were used as the monomer mixture. The average particle diameter of the obtained polymer particles was 1.2 μm.
[Production of polymer particle aggregate]
Polymer particle aggregates were obtained under the same conditions as in Example 1. The obtained polymer particle aggregate retained a spherical shape, and mutual connection due to fusion of the polymer particles was not confirmed. The average particle size of the polymer particle aggregate was 30 μm. The non-fusibility of the polymer particle aggregate was evaluated, and the results are shown in Table 1.
[Manufacture of molded products]
A molded body was produced under the same conditions as in Example 1 except that the polymer particle assembly was used and polymethyl methacrylate (Sumipex EXA, manufactured by Sumitomo Chemical Co., Ltd.) was used as the transparent base resin. In addition, no generation of scum was observed during pelletization.
The total light transmittance, haze, and diffusivity of the obtained molded product were measured, the dispersibility was evaluated, and the results are shown in Table 1.

Comparative Example 5
[Manufacture of seed particles]
Seed particles were obtained under the same conditions as in Example 1.
[Production of polymer particles]
Polymer particles were produced in the same manner as in Example 1 except that 199 g of styrene and 1 g of divinylbenzene were used as the monomer mixture, and 20 g of Luminous (manufactured by Maruo Calcium Co., Ltd .: calcium carbonate) was used as the inorganic powder. The average particle diameter of the obtained polymer particles was 1.2 μm.

[Production of polymer particle aggregate]
Polymer particle aggregates were obtained under the same conditions as in Example 1. Although the obtained polymer particle aggregate had a spherical shape, mutual connection due to fusion of the polymer particles was confirmed. The average particle diameter of the polymer particle aggregate was 31 μm. The non-fusibility of the polymer particle aggregate was evaluated, and the results are shown in Table 1.

[Manufacture of molded products]
A molded body was produced under the same conditions as in Example 1 except that the polymer particle assembly was used and polymethyl methacrylate (Sumipex EXA, manufactured by Sumitomo Chemical Co., Ltd.) was used as the transparent base resin. In addition, no occurrence of scum was observed during pelletization.
The total light transmittance, haze, and diffusivity of the obtained molded product were measured, the dispersibility was evaluated, and the results are shown in Table 1.

Comparative Example 6
[Manufacture of seed particles]
Seed particles were obtained under the same conditions as in Example 1.
[Production of polymer particles]
Polymer particles are produced in the same manner as in Example 1 except that 6 g of sodium dodecylbenzenesulfonate is used as the surfactant, 80 g of styrene and 120 g of divinylbenzene are used as the monomer mixture, and no inorganic powder is used. did. Aggregation was observed during the polymerization, and the desired polymer particles were not obtained.

Comparative Example 7
[Manufacture of seed particles]
Seed particles were obtained under the same conditions as in Example 1.
[Production of polymer particles]
Polymer particles were produced in the same manner as in Example 2.

[Production of polymer particle aggregate]
A polymer particle aggregate was obtained under the same conditions as in Example 1 except that the slurry inlet temperature of the spray dryer was 230 ° C and the polymer particle aggregate outlet temperature was 110 ° C. The obtained polymer particle aggregate retained a spherical shape, and mutual connection due to fusion of the polymer particles was confirmed. The average particle size of the polymer particle aggregate was 30 μm. The non-fusibility of the polymer particle aggregate was evaluated, and the results are shown in Table 1.

[Manufacture of molded products]
A molded body was produced under the same conditions as in Example 1 except that the polymer particle aggregate was used. In addition, no occurrence of scum was observed during pelletization.
The total light transmittance, haze, and diffusivity of the obtained molded product were measured, the dispersibility was evaluated, and the results are shown in Table 1.

In Table 1,
() Is the ratio (parts by weight) to 100 parts by weight of the monofunctional monomer and polyfunctional monomer, BA is butyl acrylate, ST is styrene, EGDMA is ethylene glycol dimethacrylate is DVB. , Divinylbenzene AIBN, azobisisobutyronitrile surfactant 1, polyoxyethylene tridecyl ether ammonium sulfate surfactant 2, dodecylbenzene sodium sulfonate PS, polystyrene PMMA, polymethacrylate PP for methyl acid means polypropylene, respectively.

Table 1 shows the following.
From Examples and Comparative Examples 5 and 6, the polyfunctional monomer is used in an amount of 1 to 100 parts by weight based on 100 parts by weight of the monofunctional monomer. It can be seen that a suppressed assembly can be obtained and that the optical properties (particularly the diffusivity) can be imparted to the molded body.

  By using 1 to 10 parts by weight of the surfactant from Examples and Comparative Examples 3 and 4 with respect to a total of 100 parts by weight of the monofunctional monomer and the polyfunctional monomer, the polymer particles are used. It can be seen that an excellent optical characteristic (particularly, diffusivity) can be imparted to the molded body by the aggregate. Moreover, the aggregate | assembly with which the mutual connection by the fusion | melting of a polymer particle was suppressed can be obtained by making the usage-amount of surfactant into 1 weight part or more.

  From Examples and Comparative Examples 1 and 2, the inorganic powder is used in an amount of 1 to 40 parts by weight based on 100 parts by weight of the total of the monofunctional monomer and the polyfunctional monomer. It can be seen that the aggregate can impart excellent optical properties (particularly diffusivity) to the molded body. In addition, by using the inorganic powder in an amount of 1 part by weight or more, it is possible to obtain an aggregate in which mutual coupling due to fusion of the polymer particles is suppressed, and it is possible to suppress the occurrence of scum on the molded body. .

  From Example and Comparative Example 7, spray drying is performed under the conditions of the slurry inlet temperature of the spray dryer of 80 to 220 ° C. and the aggregate outlet temperature of the spray dryer of 50 to 100 ° C. It can be seen that an assembly in which mutual connection by fusion is suppressed can be obtained, and that the optical properties (particularly the diffusivity) can be imparted to the molded body by the assembly.

Example 11
The molded bodies obtained in Examples 1 and 7 to 10 were subjected to the following test to evaluate high temperature durability.
(High temperature durability test)
First, the total light transmittance after leaving a measurement sample (10 samples) obtained in the same manner as the total light transmittance measuring method in an oven at 80 ° C. for 500 hours, and the total light transmittance before leaving as it is, taking measurement. From the total light transmittance after being left and the total light transmittance before being left, a reduction rate of the total light transmittance due to being left is calculated.
When the decrease rate is less than 3%, the high temperature durability is good, and when it is 3% or more, the high temperature durability is poor.
The obtained results are shown in Table 2.

  From Table 2, it can be seen that high temperature durability is improved by using a hydrophobic treated inorganic powder as the inorganic powder.

1 Molded body a Normal direction Li light L ₀ , L ₅ , L ₂₀ , L ₇₀ transmitted light

Claims (9)

A monofunctional monomer selected from styrene monomers and (meth) acrylic monomers, and a polyfunctional monomer selected from styrene monomers and (meth) acrylic monomers Comprising a polymer particle comprising a monomer mixture, a surfactant, an inorganic powder, and an aggregate of the polymer particles by spray drying a slurry containing an aqueous medium,
The polyfunctional monomer is used in an amount of 1 to 100 parts by weight based on 100 weights of the monofunctional monomer,
The surfactant is used in an amount of 1 to 10 parts by weight with respect to 100 parts by weight in total of the monofunctional monomer and the polyfunctional monomer,
The inorganic powder is used in an amount of 1 to 40 parts by weight with respect to a total of 100 parts by weight of the monofunctional monomer and polyfunctional monomer,
The spray drying, the slurry inlet temperature of 80 to 220 ° C. in a spray dryer, conducted under the conditions of collection outlet temperature of 50 to 100 ° C. in a spray drier,
The aggregate of the polymer particles is obtained by irradiating the dispersion containing 0.50 g of the aggregate of polymer particles with 50 g of water for 10 minutes with ultrasonic waves. polymer production method of particle aggregates, wherein the aggregate der Rukoto having a particle size distribution containing particles of more than 90% ± 1 [mu] m of the average particle size of the polymer particles constituting the aggregate.   The method for producing a polymer particle aggregate according to claim 1, wherein the polyfunctional monomer is ethylene glycol dimethacrylate or divinylbenzene.   The method for producing a polymer particle aggregate according to claim 1 or 2, wherein the inorganic powder is selected from calcium carbonate, colloidal silica, barium sulfate, and titanium oxide.   The method for producing a polymer particle aggregate according to any one of claims 1 to 3, wherein the inorganic powder is an inorganic powder that has been subjected to a hydrophobic treatment.   The method for producing a polymer particle aggregate according to claim 4, wherein the hydrophobized inorganic powder is hydrophobized colloidal silica or titanium oxide.   It is a polymer particle aggregate obtained by the method according to any one of claims 1 to 5, wherein the polymer particle aggregate includes 0.50 g of the polymer particle aggregate with respect to 50 g of water. Particles in the dispersion after irradiating the dispersion with ultrasonic waves for 10 minutes have a particle size distribution including 90% or more of particles having an average particle diameter of ± 1 μm of the polymer particles constituting the polymer particle aggregate. A polymer particle aggregate characterized by being a body.   The polymer particle aggregate according to claim 6, wherein the polymer particle aggregate has an average particle diameter of 2 to 250 μm.   A light diffusing agent comprising the polymer particle aggregate according to claim 6.   A light diffusing resin composition comprising 100 parts by weight of a transparent base resin and 0.01 to 40 parts by weight of the light diffusing agent according to claim 8.