JPWO2008023648A1 - Fine particles, method for producing fine particles, resin composition containing the fine particles, and optical film - Google Patents

Abstract

Provided are fine particles in which the content of coarse particles deviating from the average particle diameter is reduced to a low level, a method for producing such fine particles, and a resin composition containing the fine particles. The fine particles of the present invention are fine particles characterized in that coarse particles having a particle size of twice or more the average particle size are 1000 particles / 0.5 g or less. The production method of the present invention includes a step of wet-classifying a fine particle dispersion having a solid content concentration of 0.5 to 50% by mass and a B-type viscosity of 0.5 to 20 mPa · s, drying the fine particles after wet classification, A step of pulverizing to form fine powder particles having a water content of 0.05 to 2% by mass, and a step of dry-classifying the fine powder particles.

Description

  The present invention relates to fine particles whose particle diameter is highly controlled, and a resin composition using the same.

  Conventionally, there have been attempts to improve the physical properties or usefulness of resins and resin compositions by incorporating fine particles into resins and resin compositions used for various applications. Such attempts have also been made for optical resin materials used for optical applications such as liquid crystal displays (LCD), plasma display panels (PDP), electroluminescent displays (ELD), transmissive screens and touch panels. An optical resin composition containing fine particles made of an organic material or an inorganic material is used as a raw material for an optical resin film (sheet, plate) that imparts diffusibility and antireflection antiglare properties.

  By the way, in recent years, in the field of image display devices as described above, the trend toward larger screens and higher definition has been increasing, and the demand for peripheral technologies has increased. Various studies have been made such as improvement of the affinity with the additive), improvement of mechanical properties and optical properties of the fine particles themselves. In addition to the above required properties, fine particles used as spacers for these optical resin films and liquid crystal display elements are desired to have a narrow particle size distribution and a small content of coarse particles. ing. This is because when the particle size distribution is wide, when used as a spacer of a liquid crystal display element, it is difficult to keep the film thickness of the liquid crystal uniform and constant, and coarse particles cause scratches on the film surface, or This is because the fine particles are directly recognized and cause the display quality of the image display device to deteriorate.

For example, Patent Document 1 that discloses fine particles used for optical applications describes that, according to the method for producing the fine particles, particles having a particle size corresponding to a desired application can be obtained with a very sharp particle size distribution. ing. Moreover, in patent documents 2-4, content of the particle | grains which have a particle size which exceeds a predetermined size with respect to an average particle diameter from a viewpoint that a coarse particle causes the display quality fall of a display apparatus and the fault of an optical film. Have been proposed (Patent Document 2), and a method of removing coarse particles by filtering the fine particles in an emulsion or dispersion state before use of the fine particles (Patent Documents 2 and 4). Yes.
JP 2004-307644 A, etc. Japanese Patent Laid-Open No. 2002-166228, claims, etc. JP 2005-309399 A, claims, etc. Japanese Patent Application Laid-Open No. 2004-191956, claims, etc.

  However, as in Patent Document 1, it is actually difficult to control the particle size distribution to a high degree in the fine particle synthesis stage, and as pointed out in Patent Documents 2 to 4, the particle size distribution is also pointed out. However, if coarse particles greatly deviating from the average particle diameter are present, the display quality is deteriorated and the optical film has a defect. Therefore, the demand for reducing the amount of coarse particles tends to increase from the viewpoint of improvement in visibility and productivity, and even with the techniques of Patent Documents 2 to 4, fine particles that sufficiently satisfy such demand are obtained. It was difficult.

  The present invention has been made paying attention to the above circumstances, and the object thereof is fine particles in which the content of coarse particles deviating from a suitable particle size is reduced to a low level, and a method for producing such fine particles. And providing a resin composition containing the fine particles.

  The fine particles of the present invention that have solved the above problems have a gist where the number of coarse particles having a particle size of twice or more the average particle size is 1000 particles / 0.5 g or less.

  The fine particles are preferably an organic-inorganic composite including an organic polymer skeleton and a polysiloxane skeleton.

  The method for producing fine particles of the present invention includes a step of wet-classifying a fine particle dispersion having a solid content concentration of 0.5 to 50% by mass and a B-type viscosity of 0.5 to 20 mPa · s, drying the fine particles after wet classification, It is characterized in that it includes a step of pulverizing powder fine particles having a water content of 0.05 to 2% by mass and a step of dry-classifying the powder fine particles. In this way, raw materials (particulate dispersion liquid, powder) having specific physical properties are processed by a method combining wet classification and dry classification, so that coarse particles and fine particles deviating from the preferred range of the particle diameter can be obtained. It can be reduced more efficiently.

  An optical film obtained by applying the composition and the coating composition onto a substrate (a film having a concavo-convex shape on the surface, such as a light diffusion film or an antiglare film) is also included.

  In the fine particles of the present invention, the content of coarse particles that deviate from the preferred range of the particle size is reduced to a low level. Moreover, according to the method of the present invention, the content of fine particles can be reduced together with coarse particles that deviate from the preferred range of particle size. Therefore, it is considered that a molded product obtained from the resin composition containing the particles of the present invention is less prone to defects due to coarse particles. Further, since the content of fine particles is also reduced, it is considered that the transparency of the resin itself is hardly damaged. The fine particles of the present invention are particularly suitable for optical resin compositions, and light diffusion films, antiglare films obtained from such resin compositions, and light diffusion plates containing the fine particles of the present invention are excellent optical It is considered to show characteristics.

  The fine particles of the present invention are characterized in that the number of coarse particles having a particle size of at least twice the average particle size is 1000 particles / 0.5 g or less.

  As described above, if the fine particles used in the optical field include coarse particles that deviate from the preferred range of the particle size, the film surface may be damaged or the fine particles may be easily visually recognized. In particular, it has been confirmed by the present inventors that the above phenomenon becomes significant when fine particles having a particle size of twice or more the average particle size of the fine particles used are present (increased). Preferably, the number of coarse particles having a particle size twice or more the average particle size is 500 particles / 0.5 g or less, more preferably 200 particles / 0.5 g or less, and even more preferably 100 particles / 0.5 g. Hereinafter, it is most preferably 50 pieces / 0.5 g or less.

  Furthermore, when the amount of coarse particles is within the above range and the number of coarse particles having a particle size of 2.5 times or more of the average particle size is 50 / 0.5 g or less, when used for optical applications This is preferable because defects derived from coarse particles are less likely to occur. More preferably, it is 30 pieces / 0.5 g or less, and further preferably 10 pieces / 0.5 g or less.

  The fine particles of the present invention preferably have a reduced number of fine particles having a particle size of 1/2 or less of the average particle size. When such fine particles are contained in a large amount, the particles are transparent when used for optical purposes (for example, a light diffusing film or an antireflection antiglare film provided on an image display surface of various image display devices). There is a risk of lowering the brightness and brightness. Therefore, the fine particles having a particle size of 1/2 or less of the average particle size is preferably 10% by volume or less, more preferably 7% by volume or less.

  The average particle size of the fine particles of the present invention is not particularly limited, but is preferably 0.1 to 50 μm, more preferably 1 to 30 μm, and further preferably 2 to 20 μm. When the average particle diameter is within the above range, for example, when used for optical applications, advantageous effects such as excellent light diffusibility and surface light emission (brightness) can be obtained. If the average particle size is too small, the dispersibility in the resin as the medium may be reduced, and if it is too large, a sufficient light diffusion effect may not be obtained. In addition, the particle size distribution measurement, the average particle diameter, and the content of the fine particles are measured using a precision particle size distribution measuring apparatus (for example, “Multisizer II” manufactured by Beckman Coulter, Inc.) using the Coulter principle. And calculated on a volume basis.

  The shape of the fine particles of the present invention is not particularly limited, and examples thereof include a spherical shape, a needle shape, a plate shape, a scale shape, a pulverized shape, an uneven shape, an eyebrows shape, and a candy sugar shape. In particular, when used for optical applications (when used for an optical resin composition or the like), the shape is a perfect sphere or nearly a perfect sphere, and the ratio of the long particle diameter to the short particle diameter is 1.0 to 1. 2 and the coefficient of variation of the particle diameter is preferably 10% or less.

  The fine particles of the present invention are obtained by dry classification of fine powder particles having a predetermined water content, true specific gravity, bulk specific gravity, and particle diameter.

  The powder particles subjected to the dry classification have a water content of 0.05 to 2% by mass. When the water content is too high, the moisture works as a binder during classification, and the particles aggregate together.On the other hand, when the water content is too low, the particles aggregate due to static electricity. In addition, classification accuracy tends to be low and coarse particles tend to increase. If the water content is in the above range, the particles are difficult to aggregate, so that the classification operation can be smoothly proceeded. The true specific gravity is preferably 1 to 1.25 g / ml, the bulk specific gravity is 0.1 to 1 g / ml, and the average particle size is preferably 1 to 50 μm. If the true specific gravity of the fine powder particles is too small, the classification accuracy may be low because differences in centrifugal force due to the particle size and resistance due to wind force are unlikely to occur. If the true specific gravity is too large, large equipment and power are required, which is not preferable. On the other hand, when the bulk specific gravity is too large, large equipment and power are required, which is not preferable. On the other hand, when the bulk specific gravity is too small, a difference due to the size of the particle diameter hardly occurs, and classification accuracy may be lowered. If the particle size is too small, the powders are strongly agglomerated, and a good dispersion state may not be obtained, and classification accuracy may be reduced. If too large, large equipment and power are required, which is not preferable. .

  By wet classification, the content of powder particles used for dry classification and coarse particles more than twice the average particle size in the dispersion obtained by wet classification is set to 200,000 or less per 0.5 g. Is preferred. More preferably, it is 100,000 pieces / 0.5g or less, More preferably, it is 50,000 pieces / 0.5g or less. If the number of coarse particles of a specific size contained in the powder particles subjected to dry classification and the dispersion obtained by wet classification is within the above range, high yield and / or high can be achieved by performing dry classification. It is preferable because fine particles having a small content of coarse particles are easily obtained at a classification treatment speed.

  Therefore, the water content, true specific gravity, bulk specific gravity and particle diameter are preferably within the above ranges, and more preferably, the water content of the fine powder particles is preferably from 0.1 to 0.5% by mass. Is preferably 1 to 1.5 g / ml, the bulk specific gravity is preferably 0.3 to 0.8 g / ml, and the average particle size is preferably 2 to 20 μm.

  The “water content” is a value measured by a Karl Fischer moisture meter (for example, a moisture measuring device manufactured by Hiranuma Sangyo Co., Ltd.). The “bulk density” is the amount of powder entering the container when the powder is placed in a constant volume in a constant state, expressed as mass per unit volume. , Measured with a powder tester (manufactured by Hosokawa Micron). The “true specific gravity” of fine powder particles means that fine powder particles are filled into a container of a certain volume, and the sample void is completely replaced with liquid, and the volume of liquid required at this time is subtracted from the volume of the container. Measured by a true specific gravity measuring machine (for example, manufactured by Seishin Enterprise Co., Ltd.). The value of the particle diameter is a volume-based value measured by the precision particle size distribution measuring apparatus (for example, “Multisizer II” manufactured by Beckman Coulter, Inc.).

  For the dry classification of the fine powder particles, it is preferable to use an air classifier using wind force. An air classifier is an apparatus that separates fine particles (powder layer) according to the particle size (particle size, mass of the powder) using the air flow (that is, from the inertia of the particles and the air flow). The flying distance is determined and classified by the balance of drag force). Usually, in a classifier that uses only a sieve and a filter, the physical properties of the recovered particles depend on the sieve opening used and the filtration efficiency of the filter, so that the desired physical properties such as the particle diameter are included in a specific range. In order to obtain only the particles that can be obtained, it is necessary to perform a plurality of classification operations. On the other hand, if an airflow classifier is used, coarse particles and fine particles can be removed simultaneously.

  The classification mechanism of the airflow classifier is not particularly limited. Therefore, those using only airflow, rotating rotors that give propulsion to the airflow, guide vanes for guiding the wind, those that use the airflow generated by their combined action, and these and other A combination of classification means (a sieve or a mesh) may be used.

  Specific airflow classifiers include high-precision airflow classifiers such as the DXF type (manufactured by Nippon Pneumatic Kogyo Co., Ltd.); turbo classifier (manufactured by Nissin Engineering Co., Ltd.); Rotating rotor type air classifier with classifying rotor such as Hosokawa Micron Co., Ltd .; Air classifier (Elbow jet type classifier) using Coanda effect such as Elbow Jet (manufactured by Nippon Steel Mining Co., Ltd.); And airflow classifiers using mesh openings such as a dry sieve blower shifter (manufactured by Yugrop Co., Ltd.). Among these, a high-accuracy air classifier, a rotary rotor type air classifier, and an air classifier using the Coanda effect are preferable because coarse particles can be efficiently removed.

  The above high-accuracy air classifier has no moving parts (movable members) and generates a high-speed swirling air flow by the inflow air to the dispersion zone and the classification zone to give centrifugal force to the particles supplied into the apparatus. At the same time, it is an apparatus that exhausts air from the classification zone by a suction blower so as to be a drag of the centrifugal force applied to the particles, and classifies the coarse powder and fine powder from the particles by the balance between the centrifugal force and the drag. The rotating rotor type airflow classifier is equipped with a freely rotatable cylinder (classifying rotor) and an intake port for taking air into the device from the outside of the device. The rotor rotates at a high speed to generate eddy currents in the device. Centrifugal force due to vortex flow is applied to the particles supplied to the air, while air is taken in from the intake port so as to be a drag of the centrifugal force, and the coarse and fine particles are classified from the particles by the balance of the centrifugal force and the drag. It is a device to do. The air classifier using the Coanda effect is a device that uses the Coanda effect that the jet flows along the wall surface when the wall surface is placed only on one side of the jet stream. Ejector that is jetted into the device together with air), a Coanda block that guides the jet (including particles) into the classification chamber, and the particles are separated according to properties (coarse powder, fine powder (target product), fine powder, etc.) A classification edge is provided at an arbitrary position. The jet (including particles) ejected from the ejector section tends to flow along the Coanda block. At this time, there is a difference between the inertial force acting on the particles and the inertial force acting between the microparticles and the coarse particles (the coarse particles try to fly farther away), and due to the balance of fluid resistance, the coarse particles and the microparticles Classified.

  Among the above airflow classifiers, airflow classifiers (elbow jet classifiers) that utilize the Counder effect are preferable. When this elbow jet type classifier is used, it is preferable to raise the feed air to the maximum recommended air pressure in order to improve the classification accuracy. Normally, the feed air is operated at 0.1 to 10 kgf, but it is recommended that the feed air is 1 to 5 kgf from the viewpoint of improving the classification accuracy. In general, if the feed air is increased too much, the flight distance of coarse particles becomes long, and there is a high possibility that coarse particles that bounce off the front wall will be mixed into the fine powder. However, the fine particles according to the present invention are obtained through a wet classification process and then a dry classification process, as will be described later, and since the coarse particles are removed to some extent in the wet classification process, the coarse particles due to rebounding are obtained. There is no mixing in fine powder. Therefore, classification accuracy can be improved by raising the feed air.

  It is also preferable to use a slim edge as the classification edge in order to improve classification accuracy. As described above, the classification edge is used for isolating particles according to properties, and has a wedge-shaped shape in which one end (particle entry side) is thin and becomes thicker toward the other end. ing. Further, the bottom cross section (one end having a thickness in the wedge shape) is substantially rectangular and has a specific width. Note that the width of the classification edge is usually designed to be approximately equal to the width of the flow path through which the jet flow containing particles flows. Here, the slim edge is formed such that the distance between the wedge-shaped slopes is shorter than that of the standard edge that is normally used (particularly, about half of the standard edge in the bottom cross-sectional portion). The slim edge is usually used to prevent particles from accumulating at the tip of the edge and reducing classification accuracy when processing strongly charged particles. The reason why the classification accuracy is improved by using the slim edge is considered to be because the disturbance of the airflow hardly occurs in addition to the purpose of the slim edge (suppression of the decrease in the classification accuracy due to particle deposition).

  The fine powder particles subjected to the dry classification are obtained by wet classification of a fine particle dispersion having a solid content concentration of 0.5 to 50% by mass and a B-type viscosity of 0.5 to 20 mPa · s, followed by drying and pulverization. Those are preferred. The solid content concentration of the fine particle dispersion is preferably 0.5 to 20% by mass, and the B-type viscosity is preferably 0.5 to 10 mPa · s.

  When the solid content concentration of the fine particle dispersion solution supplied to the wet classifier is high or the viscosity is high, classification takes a long time, the load on the mesh increases, and the mesh opening increases and becomes larger. There is a possibility that the classification accuracy is lowered. Further, when the solid content concentration is less than 0.5% by mass, the classification takes a long time.

  Moreover, it is preferable that the particles to be subjected to wet classification have a small content of coarse particles larger than a particle size that is twice the average particle size. Specifically, it is preferable that the content of coarse particles larger than a particle size twice the average particle size is 1 million or less per 0.5 g. More preferably, it is 500,000 pieces / 0.5 g, and more preferably 200,000 pieces / 0.5 g or less.

  The fine particle dispersion may be prepared by dispersing fine particles produced in advance in a dispersion medium (water, organic solvent, etc.). When the fine particles are made of an organic polymer or an organic-inorganic composite material described later, a polymerization reaction is performed. The subsequent reaction solution may be used as it is. Moreover, you may use the fine particle dispersion obtained by the wet process as it is.

  An apparatus that can be used for wet classification of the fine particle dispersion is not particularly limited, and examples thereof include a filtering apparatus using a filter and a sieve, a centrifugal force, and a hydrocyclone apparatus using an inertial force. Specific wet classifiers include cartridge filters (for example, manufactured by Loki Techno Co., Ltd., Nippon Ball Co., Ltd.), and liquid cyclones (for example, manufactured by Rasa Industrial Co., Ltd., manufactured by Industria Co., Ltd.) that perform centrifugal classification. It is done.

  Multiple cartridge filters may be used in combination. For example, for the purpose of reducing running costs by extending the service life, a final filter that satisfies the required filtration accuracy is combined with a prefilter that is used to extend the life of the final filter. May be used. However, the final filter selection criteria is preferably a type that can remove 50% by mass or more of particles that are twice the average particle size. For example, an SLP type cartridge filter manufactured by Loki Techno Co., Ltd. is preferable as a final filter because it has a filter material thickness that is a feature of a depth filter and a wide filter area that is a feature of a pleated filter. As a selection criterion for the pre-filter, it is desirable to use a type capable of filtering 50% by mass or more of particles having an average particle size of 3 times or more.

  The liquid cyclone device is a device that uses a liquid as a medium and classifies particles dispersed in the liquid by centrifugal force. For example, in the case of a device having a cylindrical (or conical) portion, a fine particle dispersion is supplied from the tangential direction of the cylindrical portion of the device, and coarse particles are centrifuged while the fine particle dispersion descends the cylindrical portion as a swirling flow. It is moved in the radial direction by the action of a force to collide with the inner wall of the cylinder, dropped along the inner wall to the lower part of the apparatus, and then recovered from the lower part of the apparatus. On the other hand, since the fine particles move upward along the upward swirling flow generated near the center, the fine particles are collected from the upper part of the device.

  The particles after wet classification are preferably dried and pulverized. The drying and pulverization conditions were as follows: physical properties of the fine powder particles described above (water content 0.05-2% by mass, true specific gravity 1-1.25 g / ml, bulk specific gravity 0.1-1 g / ml, particle size 1 50 μm) can be satisfied, and there is no particular limitation.

  The fine particles of the present invention are obtained by dry-classifying fine powder particles having predetermined physical properties, but other classification means may be combined as necessary, and in particular, the fine particle fine particles are prepared as described above. It is recommended that the wet classification process is used from the viewpoint of reducing the content of coarse particles and fine particles to a low level. That is, a preferable process for obtaining the fine particles of the present invention includes a process of subjecting a fine particle dispersion having predetermined physical properties to wet classification, drying and pulverizing the particles after wet classification, and further dry classification. By passing through such a process, the fine particles of the present invention in which coarse particles having a particle size of twice or more the average particle size are 1000 or more / 0.5 g or less can be obtained more efficiently.

  Next, the structure and manufacturing method of the fine particles according to the present invention will be described.

  The form of the fine particles according to the present invention is not particularly limited, and may be any of an organic polymer, an inorganic material, and an organic / inorganic composite material. Examples of the organic polymer include linear polymers such as polystyrene, polymethyl methacrylate, polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polysulfone, polycarbonate, and polyamide; divinylbenzene, hexatriene, divinyl ether, divinylsulfone, diallylcarbyl Nord, alkylene diacrylate, oligo or polyalkylene glycol diacrylate, oligo or polyalkylene glycol dimethacrylate, alkylene triacrylate, alkylene tetraacrylate, alkylene trimethacrylate, alkylene tetramethacrylate, alkylene bisacrylamide, alkylene bismethacrylamide, acrylic at both ends Modified polybutadiene oligomer alone or other Reticulated polymer obtained by polymerizing a polymerizable monomer; amino compounds (e.g., benzoguanamine, melamine or urea) and the organic polymer and the like made from the resulting amino resin by polycondensation reaction of formaldehyde.

  Examples of the organic-inorganic composite material include (A) fine particles in which inorganic fine particles such as metal oxides such as silica, alumina, and titania, metal nitrides, metal sulfides, and metal carbides are dispersed and contained in organic resins; B) Fine particles in which metalloxane chains (molecular chains including a “metal-oxygen-metal” bond) such as (organo) polysiloxane and polytitanoxane and organic molecules are combined at the molecular level, and organoalkoxysilanes such as methyltrimethoxysilane Of silicon-based fine particles such as polymethylsilsesquioxane obtained by hydrolysis and condensation reaction of polysiloxane, and polysiloxane and polymerizable group (for example, vinyl group) made from a silicon compound having a hydrolyzable silyl group (C) , (Meth) acryloyl group, etc.), an organic polymer skeleton obtained by reacting with a polymerizable monomer, etc. , Organic and inorganic composite material containing a polysiloxane skeleton.

  Examples of the inorganic material include glass, silica, alumina, and the like.

  Among the above examples, fine particles made of an organic polymer or organic-inorganic inorganic composite material are preferable because the characteristics of the fine particles can be designed relatively freely and particles having a sharp particle size distribution can be easily obtained. Further, among the fine particles made of an organic polymer, the organic polymer made of an amino resin and the organic polymer particles obtained by the seed polymerization method (the ratio of the crosslinkable monomer to the total amount of the polymerizable monomer is more preferably 20% by mass or more. Is preferably 30% by mass or more, more preferably 50% by mass or more, and (C) is particularly preferable among the fine particles made of the organic-inorganic composite material. Further, these particles are hardened or cross-linked during the synthesis process, and are hardly dissolved or swollen by an organic solvent. Therefore, when used in a coating resin composition for forming a light diffusing layer and an antiglare layer, which will be described later, even if used simultaneously with an organic solvent or the like, the particles are unlikely to change in quality or change in particle diameter. This is preferable because the effect of reducing the particles within the above range can be sufficiently obtained.

  These particles are preferably subjected to a wet classification process in the state of a particle suspension obtained at the time of synthesis of each particle. That is, it is because it is easy to obtain a suspension having a small content (for example, less than 1 million particles / 0.5 g) of coarse particles more than twice the average particle size. In particular, fine particles made of an organic-inorganic composite material and organic polymer fine particles made of an amino resin obtained by a preferable production method described below are preferred.

  The particles preferably have a particle diameter variation coefficient (based on a particle size distribution calculated on a volume basis) of 20% or less. More preferably, it is 10% or less. The smaller the value of the coefficient of variation of the particle size, the less the variation in the particle size.If the above range is satisfied, the amount of coarse particles contained in the fine particles after the wet classification and dry classification processes is reduced. It is preferable because it is easy. Here, the variation coefficient of the particle diameter is a value calculated from the following formula.

Here, σ represents the standard deviation of the particle diameter, and X represents the average particle diameter.

  In the present invention, the average particle size and the standard deviation of the particle size were measured using the above-described precision particle size distribution measuring apparatus (for example, “Multisizer II” manufactured by Beckman Coulter, Inc.) and calculated on a volume basis.

  Here, the structure and manufacturing method of the fine particles (amino resin) made of the organic polymer and the fine particles (above (C)) made of the organic-inorganic composite material will be described.

<Method for producing amino resin crosslinked particles>
First, a method for producing an amino resin (amino resin crosslinked particles) that is fine particles made of the organic polymer will be described.

  As a manufacturing method of amino resin crosslinked particle, the 1st manufacturing method and the 2nd manufacturing method which are demonstrated below are mentioned. According to these first and second production methods, since the particle diameter can be controlled in the fine particle synthesis stage, the generation of coarse particles can be somewhat suppressed. Therefore, by subjecting the amino resin crosslinked particles obtained by the production method to the process for obtaining the fine particles according to the present invention described above, it is easier to reduce the content of particles that deviate from the preferred range of the particle size. This is preferable because it can be performed. First, the first manufacturing method will be described.

-First manufacturing method-
The first production method of amino resin crosslinked particles (hereinafter sometimes simply referred to as “first production method”) is a resinification step of obtaining an amino resin precursor by reacting an amino compound with formaldehyde. And emulsifying the amino resin precursor obtained in the resinification step in an aqueous medium to obtain an emulsion of the amino resin precursor, and adding a catalyst to the emulsion obtained in the emulsification step. A curing step of carrying out a curing reaction of the emulsified amino resin precursor to obtain amino resin crosslinked particles.

  The resinification step is a step in which an amino compound and formaldehyde are reacted to generate an amino resin precursor that is an initial condensation reaction product. Water is used as a solvent for reacting the amino compound with formaldehyde. Specific methods for carrying out the resinification step include a method in which an amino compound is added to formaldehyde in the form of an aqueous solution (formalin), and a reaction. A method in which trioxane or paraformaldehyde is added to water to formaldehyde in water. Preferred examples include a method in which an amino compound is added to an aqueous solution prepared so as to cause a reaction. Among these, the former method is more preferable from the viewpoint of economy because it does not require a preparation tank for an aqueous formaldehyde solution and it is easy to obtain raw materials. Moreover, even if it employ | adopts any method, it is preferable to perform a resinification process under stirring by a well-known stirring apparatus etc.

  The amino compound used as a starting material in the resinification step is not particularly limited. For example, benzoguanamine (2,4-diamino-6-phenyl-sym.-triazine), cyclohexanecarboguanamine, cyclohexenecarboguanamine and melamine Etc. Among these, amino compounds having a triazine ring are more preferable. In particular, since benzoguanamine has a benzene ring and two reactive groups, when benzoguanamine is included as an amino compound, the resulting amino resin crosslinked particles are flexible (hardness), stain resistant, and heat resistant. Particularly preferred because of its excellent solvent resistance and chemical resistance. The amino compounds may be used alone or in combination of two or more.

  In the total amount of the amino compound to be used, the proportion of the above-described amino compounds (benzoguanamine, cyclohexanecarboguanamine, cyclohexenecarboguanamine and melamine) is preferably 40% by mass or more, more preferably 60% by mass. % Or more, more preferably 80% by mass or more, and most preferably 100% by mass. When the content of the amino compound is 40% by mass or more, the produced amino resin crosslinked particles are excellent in heat resistance and solvent resistance.

  The molar ratio (amino compound (mol) / formaldehyde (mol)) of the amino compound and formaldehyde to be reacted in the resinification step is preferably 1 / 3.5 to 1 / 1.5, and 1/3 More preferably, the ratio is from 5 to 1 / 1.8, and even more preferably from 1-3.2 to 1/2. If the molar ratio is less than 1 / 3.5, the unreacted formaldehyde may increase. If it exceeds 1 / 1.5, the unreacted amino compound may increase.

In addition, as long as there is no trouble in reaction, the density | concentration of the amino type compound and formaldehyde at the time of preparation of a resinification process is desirable to be higher concentration. Specifically, the viscosity of the reaction solution containing the amino resin precursor as a reaction product within a temperature range of 95 to 98 ° C. is 2 × 10 ^{−2 to} 5.5 × 10 ⁻² Pa · s (20 It is preferable that the concentration be adjusted and controlled within a range of ˜55 cP). More preferably, in the emulsification step to be described later, the reaction solution is added to the aqueous solution of the emulsifier so that the concentration of the amino resin precursor in the emulsion is in the range of 30 to 60% by mass. What is necessary is just the density | concentration which can add the aqueous solution of an emulsifier.

Therefore, the viscosity of the reaction solution containing the amino resin precursor obtained in the resinification step within a temperature range of 95 to 98 ° C. is 2 × 10 ^{−2 to} 5.5 × 10 ⁻² Pa · s (20 to 55 cP). ), More preferably 2.5 × 10 ^{−2 to} 5.5 × 10 ⁻² Pa · s (25 to 55 cP), and even more preferably 3.0 × 10 ^{−2 to} 5.5 ×. 10 ⁻² Pa · s (30 to 55 cP). As the method for measuring the viscosity, a method using a viscosity measuring machine that can grasp the progress of the reaction immediately (in real time) and can accurately determine the end point of the reaction is optimal. As such a viscometer, a vibration viscometer (manufactured by MIVIITS Japan, product name: MIVI6001) can be used. This viscometer has a vibrating part that constantly vibrates. By immersing the vibrating part in the reaction liquid, the viscosity of the reaction liquid increases and a load is applied to the vibrating part. Is immediately converted into viscosity and displayed.

By reacting an amino compound and formaldehyde in water (in an aqueous medium), an amino resin precursor that is a so-called initial condensate is obtained. The reaction temperature is preferably in the temperature range of 95 to 98 ° C. so that the progress of the reaction can be immediately grasped and the end point of the reaction can be accurately determined. The reaction between the amino compound and formaldehyde is carried out by cooling the reaction liquid when the viscosity of the reaction liquid falls within the range of 2 × 10 ^{−2 to} 5.5 × 10 ⁻² Pa · s. What is necessary is just to complete | finish by operating. Thereby, the reaction liquid containing an amino resin precursor is obtained. The reaction time is not particularly limited.

  The amino resin precursor obtained in the resinification step is a molar ratio of the structural unit derived from the amino compound constituting the amino resin precursor to the structural unit derived from formaldehyde (the structural unit derived from the amino compound (mol) / formaldehyde). The derived structural unit (mol) is preferably 1 / 3.5 to 1 / 1.5, more preferably 1 / 3.5 to 1 / 1.8, and 1 / 3.2. More preferably, it is -1/2. When the molar ratio is within the above range, particles having a narrow particle size distribution can be obtained.

  Amino resin precursors are usually soluble in organic solvents such as acetone, dioxane, methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl alcohol, ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, methyl ethyl ketone, toluene, and xylene. However, it is substantially insoluble in water.

In the first production method, the particle diameter of the finally obtained amino resin crosslinked particles can be reduced by reducing the viscosity of the reaction liquid in the resinification step of preparing the reaction liquid containing the amino resin precursor. it can. However, when the viscosity of the reaction solution is less than 2 × 10 ⁻² Pa · s, or exceeds 5.5 × 10 ⁻² Pa · s, the particle sizes are finally almost uniform (the particle size distribution is Narrow) amino resin crosslinked particles may be difficult to obtain. That is, when the viscosity of the reaction solution is less than 2 × 10 ⁻² Pa · s (20 cP), the stability of the emulsion obtained in the emulsification step described later becomes poor. For this reason, when the amino resin precursor is cured in the curing step, the resulting amino resin crosslinked particles may be enlarged or the particles may aggregate, and the particle diameter of the amino resin crosslinked particles cannot be controlled. There is a possibility that the amino resin crosslinked particles having a wide particle size distribution may be obtained. In addition, when the stability of the emulsion is poor, the particle diameter (average particle diameter) of the amino resin crosslinked particles changes every time of production (for each batch), which may cause variations in the product. . On the other hand, when the viscosity of the reaction solution exceeds 5.5 × 10 ⁻² Pa · s (55 cP), the load applied to the high-speed stirrer used in the emulsification step described later is too large, and the shear force is reduced. There is a possibility that the reaction solution cannot be sufficiently stirred (emulsified). For this reason, it becomes difficult to control the particle diameter of the finally obtained amino resin crosslinked particles, which may result in amino resin crosslinked particles having a wide particle size distribution. Therefore, it is preferable to adjust the reaction liquid in the above viscosity range in advance in the resinification step.

  The emulsification step is a step of preparing an amino resin precursor emulsion by emulsifying the amino resin precursor obtained in the resinification step. In emulsifying the amino resin precursor, for example, an emulsifier that can form a protective colloid is preferably used, and an emulsifier made of a water-soluble polymer that can form a protective colloid is particularly preferable.

  Examples of the emulsifier include polyvinyl alcohol, carboxymethyl cellulose, sodium alginate, polyacrylic acid, water-soluble polyacrylate, and polyvinyl pyrrolidone. These emulsifiers may be used in the form of an aqueous solution in which the entire amount is dissolved in water, or a part of the emulsifier is used in the form of an aqueous solution, and the rest is used as it is (for example, powder, granule, liquid, etc.). May be. Among the emulsifiers exemplified above, polyvinyl alcohol is more preferable in consideration of the stability of the emulsion, interaction with the catalyst, and the like. Polyvinyl alcohol may be a completely saponified product or a partially saponified product. Moreover, the polymerization degree of polyvinyl alcohol is not particularly limited.

  It is preferable that the usage-amount of an emulsifier is 1-30 mass parts with respect to 100 mass parts of amino resin precursors obtained at the said resinification process, and it is more preferable that it is 1-5 mass parts. If the amount used is outside the above range, the stability of the emulsion may be poor. In addition, the larger the amount of emulsifier used relative to the amino resin precursor, the smaller the particle size of the particles produced.

  In the emulsification step, for example, the reaction solution obtained in the resinification step is added to the aqueous solution of the emulsifier so that the concentration of the amino resin precursor (that is, the solid content concentration) is in the range of 30 to 60% by mass. Then, it is preferable to make it emulsion within the temperature range of 50-100 degreeC. More preferably, it is 60-100 degreeC, More preferably, it is 70-95 degreeC. The concentration of the aqueous solution of the emulsifier is not particularly limited as long as the concentration of the amino resin precursor can be adjusted within the above range. If the concentration of the amino resin precursor is less than 30% by mass, the productivity of the amino resin crosslinked particles may be reduced. If the concentration exceeds 60% by mass, the resulting amino resin crosslinked particles are enlarged or the particles are aggregated. There is a risk that control of the particle diameter of the amino resin crosslinked particles becomes difficult, and the particle size distribution of the resulting amino resin crosslinked particles may be widened.

  In the emulsification step, it is preferable to use an apparatus (an apparatus having a high shearing force) capable of more powerfully stirring the amino resin precursor and the aqueous solution of the emulsifier as a stirring means. Specific examples of the stirrer include, for example, a so-called high-speed stirrer, homomixer, TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), high-speed disper, Ebara Mileser (manufactured by Ebara Corporation), (Izumi Food Machinery Co., Ltd.), static mixer (manufactured by Noritake Company Limited), and the like.

  In the emulsification step, it is preferable to promote emulsification until the amino resin precursor obtained in the resinification step has a predetermined particle size. In addition, what is necessary is just to set a predetermined particle diameter suitably so that the amino resin bridge | crosslinking particle | grains of a desired particle diameter may be finally obtained. Specifically, emulsification is performed so that the average particle diameter of the emulsified amino resin precursor is 0.1 to 20 μm by appropriately considering the type of the container and the stirring blade, the stirring speed, the stirring time, the emulsification temperature, and the like. More preferably, it is 0.5-20 micrometers, More preferably, it is 1-5 micrometers. Thus, by emulsifying the amino resin precursor so as to be in the above particle diameter range, the particle diameter of the amino resin crosslinked particles can be controlled within a desired range.

In the first production method, if necessary, inorganic particles are added to the emulsion obtained after the emulsification step in order to more reliably prevent the finally obtained amino resin crosslinked particles from agglomerating firmly. Can be added. Specific examples of inorganic particles include silica fine particles, zirconia fine particles, aluminum powder, alumina sol, and serie sol. Among them, silica fine particles are more preferable because they are easily available. Preferably the specific surface area of the inorganic particles is 10 to 400 m ² / g, more preferably 20~350m ² / g, even more preferably 30~300m ² / g. The particle diameter of the inorganic particles is more preferably 0.2 μm or less, more preferably 0.1 μm or less, and even more preferably 0.05 μm or less. When the specific surface area and the particle diameter are within the above ranges, a further excellent effect can be exhibited in preventing the finally obtained amino resin crosslinked particles from being strongly aggregated.

  The method of adding the inorganic particles to the emulsion is not particularly limited. Specifically, for example, the method of adding the inorganic particles as they are (particulate form) or the dispersion in which the inorganic particles are dispersed in water. The method of adding in the state of a liquid etc. are mentioned. The amount of inorganic particles added to the emulsion is preferably 1 to 30 parts by weight, more preferably 2 to 28 parts by weight, and even more, with respect to 100 parts by weight of the amino resin precursor contained in the emulsion. Preferably it is 3-25 mass parts. If it is less than 1 part by mass, it may not be possible to sufficiently prevent the finally obtained amino resin crosslinked particles from agglomerating firmly. If it exceeds 30 parts by mass, aggregates of only inorganic particles are generated. There is a risk. Moreover, as a stirring method at the time of adding inorganic particles, the method using the above-described apparatus having a high shearing force is preferable in that the inorganic particles are firmly fixed to the amino resin particles.

  In the curing step, a catalyst (specifically a curing catalyst) is added to the emulsion prepared in the emulsification step, and the emulsified amino resin precursor is cured (the amino resin precursor is cured in an emulsion state). To produce amino resin crosslinked particles (specifically, suspension of amino resin crosslinked particles).

  As the catalyst (curing catalyst), an acid catalyst is suitable. Acid catalysts include mineral acids such as hydrochloric acid, sulfuric acid and phosphoric acid; ammonium salts of these mineral acids; sulfamic acids; sulfonic acids such as benzenesulfonic acid, paratoluenesulfonic acid and dodecylbenzenesulfonic acid; phthalic acid, benzoic acid, Organic acids such as acetic acid, propionic acid, salicylic acid and the like can be used. Of the acid catalysts exemplified above, a mineral acid is preferable in terms of curing speed, and sulfuric acid is more preferable in terms of corrosiveness to the apparatus, safety when using a mineral acid, and the like. Moreover, when using a sulfuric acid as said catalyst, compared with the case where a dodecylbenzenesulfonic acid is used, for example, the amino resin bridge | crosslinking particle | grains finally obtained are hard to discolor, and since a solvent resistance is high, it is preferable. These acid catalysts may be used alone or in combination of two or more.

  The amount of the catalyst used is preferably 0.1 to 5 parts by mass, more preferably 0.3 to 4 parts per 100 parts by mass of the amino resin precursor in the emulsion obtained by the emulsification step. 0.5 parts by mass, and still more preferably 0.5 to 4.0 parts by mass. When the amount of the catalyst used exceeds 5 parts by mass, the emulsion state may be destroyed and the particles may be aggregated. When the amount is less than 0.1 parts by mass, the reaction takes a long time or is cured. May become insufficient. Similarly, the amount of the catalyst used is preferably 0.002 mol or more, more preferably 0.005 mol or more, and still more preferably 0.002 mol or more with respect to 1 mol of the amino compound used as the raw material compound. 01-0.1 mol. When the amount of the catalyst used is less than 0.002 mol relative to 1 mol of the amino compound, the reaction may take a long time or curing may be insufficient.

  In the curing reaction in the curing step, the reaction solution (emulsion) is preferably held at 15 (normal temperature) to 80 ° C., more preferably 20 to 70 ° C., and even more preferably 30 to 60 ° C. for at least 1 hour, It is preferably carried out at a temperature in the range of 60 to 150 ° C., more preferably 60 to 130 ° C., and still more preferably 60 to 100 ° C. under normal pressure or increased pressure. If the reaction temperature of the curing reaction is less than 60 ° C., the curing does not proceed sufficiently, and the solvent resistance and heat resistance of the resulting amino resin crosslinked particles may be reduced. On the other hand, when the reaction temperature exceeds 150 ° C., a strong pressure reactor is required, which is not economical. The end point of the curing reaction may be judged by sampling or visual observation. Further, the reaction time of the curing reaction is not particularly limited.

  The curing step is preferably performed under stirring, and a known stirring device may be used as the stirring means. In the curing step, the average particle diameter of the amino resin crosslinked particles obtained by curing the amino resin precursor in the emulsion state is preferably 0.1 to 20 μm, more preferably 0.5 to 20 μm, and even more. Preferably it is 1-5 micrometers.

  The first production method may include a coloring step of adding an aqueous solution obtained by dissolving a dye in water to an emulsion of an amino resin precursor or a suspension of amino resin crosslinked particles.

  In the 1st manufacturing method, you may provide the neutralization process of neutralizing the suspension containing the amino resin bridge | crosslinking particle | grains obtained by the said hardening process. The neutralization step is preferably performed when an acid catalyst such as sulfuric acid is used as the curing catalyst in the curing step. By performing the neutralization step, the acid catalyst can be removed (specifically, the acid catalyst can be neutralized). For example, in the heating step described later, the amino resin when the amino resin crosslinked particles are heated. It is possible to suppress discoloration of the crosslinked particles (for example, discoloration to yellow).

  “Neutralization” in the neutralization step means that the pH of the suspension containing the amino resin crosslinked particles is 5 or more, more preferably 5-9. When the pH of the suspension is less than 5, since the acid catalyst remains, the amino resin crosslinked particles may be discolored in the heating step described later. By adjusting the pH of the suspension to the above range by neutralization, amino resin crosslinked particles having high hardness, excellent solvent resistance and heat resistance, and no discoloration can be obtained. As a neutralizing agent that can be used in the neutralization step, for example, an alkaline substance is suitable. Examples of the alkaline substance include sodium carbonate, sodium hydroxide, potassium hydroxide, and ammonia. Among them, sodium hydroxide is preferable in terms of easy handling, and an aqueous sodium hydroxide solution is preferably used. . These may be used alone or in combination of two or more.

  In the first production method, a separation step of taking out the amino resin crosslinked particles from the suspension of amino resin crosslinked particles obtained after the curing step or after the neutralization step may be provided.

  As a method for removing amino resin crosslinked particles from the suspension (separation method), a method of separating by filtration or a method of using a separator such as a centrifugal separator is mentioned as a simple method, but is not particularly limited, Any generally known separation method can be used.

  In addition, you may wash | clean the amino resin crosslinked particle after taking out from suspension with water etc. as needed.

  In the first production method, it is preferable to perform a heating step of heating the amino resin crosslinked particles taken out through the separation step at a temperature of 130 to 190 ° C. By performing the heating step, moisture adhering to the amino resin crosslinked particles and remaining free (unreacted) formaldehyde can be removed, and condensation (crosslinking) in the amino resin crosslinked particles is further promoted. be able to. When the heating temperature is lower than 130 ° C., condensation (crosslinking) in the amino resin crosslinked particles cannot be sufficiently promoted, and the hardness, solvent resistance and heat resistance of the amino resin crosslinked particles can be improved. If it exceeds 190 ° C, the resulting amino resin crosslinked particles may be discolored. Even when the above-described neutralization step is performed, the effect when the heating temperature is outside the above temperature range is the same. From the viewpoint of improving various properties (hardness, solvent resistance, heat resistance, and discoloration resistance) of the resulting amino resin crosslinked particles, the heating temperature of the amino resin crosslinked particles is within the above range after performing a neutralization step. Is preferable.

  The heating method in the heating step is not particularly limited, and a generally known heating method may be used. What is necessary is just to complete | finish a heating process, for example in the stage in which the moisture content of amino resin bridge | crosslinking particle | grains became 3 mass% or less (more preferably 2 mass% or less). Further, the heating time is not particularly limited.

  The amino resin crosslinked particles obtained by the first production method were separated from the aqueous medium at the time of emulsification, dried and pulverized, and then the obtained pulverized product was dispersed in a solvent to form a suspension. Can also be supplied to wet and dry classification processes. It is also possible to subject the suspension after the curing step (including any suspension obtained after the curing step to the separation step such as the suspension obtained through the neutralization step) to wet classification. This is a preferred embodiment of the inventive method. The suspension after wet classification is dried and pulverized after the above-described separation step and heating step as necessary, to obtain fine powder particles having a moisture content of 0.05 to 2% by mass, and this is dry-type It is preferable to use for a classification process.

  Next, the 2nd manufacturing method of amino resin crosslinked particle is demonstrated.

-Second manufacturing method-
The second production method of amino resin crosslinked particles (hereinafter sometimes simply referred to as “second production method”) refers to an amino resin precursor obtained by reacting an amino compound with formaldehyde. The amino resin precursor is granulated and precipitated in the aqueous medium by mixing with a surfactant in an aqueous medium and adding a catalyst to the mixture, and then the amino resin crosslinked particles are removed from the aqueous medium. This is a method of separating and drying, and crushing the obtained dried product.

  In the second production method, as in the first production method, a resinification step is adopted, and in the resinification step, an amino compound and formaldehyde are reacted to produce an amino resin precursor. The method employs a mixing step in which the amino resin precursor obtained in the resinification step is mixed with a surfactant in an aqueous medium, and a catalyst is added to the mixed solution containing the amino resin precursor and the surfactant to form an amino acid. It differs from the first production method in that the resin precursor is granulated and precipitated by curing and adopts a curing and granulating step for obtaining amino resin crosslinked particles.

  In the second production method, amino resin crosslinked particles having a small particle diameter can be easily prepared by starting the curing of the amino resin precursor in an aqueous solution state (for example, the average particle diameter is 0.1 to 50 μm).

  In addition, as an amino compound used with the 2nd manufacturing method, it is preferable to set the kind and composition ratio suitably so that the grade of the water miscibility mentioned later may be satisfy | filled. For example, it is more preferable to use an amino compound that can react with formalin to produce a water-soluble amino resin precursor.

  Moreover, it is preferable that the amino resin precursor obtained by a resinification process is water-soluble. The surfactant used in the second production method is used for imparting water affinity to the aqueous medium of the amino resin precursor, and the surfactant used in the first production method is the emulsifier used in the first production method. Not included.

  In the present invention, the water affinity is expressed in terms of mass% (hereinafter referred to as “water”) at 15 ° C. with respect to the initial condensate, which is the amount of water dropped until water is added to the amino resin precursor as the initial condensate to cause cloudiness. The higher the value, the higher the water affinity. In addition, the water miscibility of the amino resin precursor suitable for the second production method is 100% or more. With amino resin precursors having a water miscibility of less than 100%, no matter how they are dispersed in an aqueous liquid containing a surfactant, only a non-uniform suspension having a relatively large particle size is formed. The spherical fine particles obtained in the above are unlikely to have a uniform particle size (wide particle size distribution).

In the mixing step, the amino resin precursor obtained in the resinification step is mixed with a surfactant in an aqueous medium by stirring or the like to prepare a mixed solution.

As the surfactant, for example, all surfactants such as an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant can be used. Nonionic surfactants or mixtures thereof are preferred.

  Anionic surfactants include alkali metal alkyl sulfates such as sodium dodecyl sulfate and potassium dodecyl sulfate; ammonium alkyl sulfates such as ammonium dodecyl sulfate; sodium dodecyl polyglycol ether sulfate; sodium sulforicinoate; Alkyl sulfonates such as alkali metal salts, ammonium salts of sulfonated paraffins; fatty acid salts such as sodium laurate, triethanolamine oleate, triethanolamine abiates; alkalis of sodium dodecylbenzene sulfonate, alkali phenol hydroxyethylene Alkyl aryl sulfonates such as metal sulfates; high alkyl naphthalates A sulfonate salt; a naphthalene sulfonic acid formalin condensate; a dialkyl sulfosuccinate salt; a polyoxyethylene alkyl sulfate salt; a polyoxyethylene alkyl aryl sulfate salt, and the like. As a nonionic surfactant, a polyoxyethylene alkyl ether; Polyoxyethylene alkyl aryl ethers; sorbitan fatty acid esters; polyoxyethylene sorbitan fatty acid esters; fatty acid monoglycerides such as monolaurate of glycerol; polyoxyethyleneoxypropylene copolymers; condensation of ethylene oxide with aliphatic amines, amides or acids Products etc. can be used.

  The amount of the surfactant used is preferably in the range of 0.01 to 10 parts by mass with respect to 100 parts by mass of the amino resin precursor obtained in the resinification step. If the amount is less than 0.01 parts by weight, a stable suspension of amino resin crosslinked particles may not be obtained. If the amount exceeds 10 parts by weight, unnecessary foaming may occur in the suspension. The physical properties of the resulting amino resin crosslinked particles may be adversely affected.

  In the mixing step, for example, the reaction solution obtained in the resinification step so that the concentration of the amino resin precursor (that is, the solid content concentration) is in the range of 3 to 25% by mass in the surfactant aqueous solution. After adding, it is preferable to mix. In this case, the concentration of the surfactant aqueous solution is not particularly limited as long as the concentration of the amino resin precursor can be adjusted within the above range. If the concentration of the amino resin precursor is less than 3% by mass, the productivity of the amino resin crosslinked particles may be reduced. If the concentration exceeds 25% by mass, the resulting amino resin crosslinked particles may be enlarged or particles may be May agglomerate, and the particle diameter of the amino resin crosslinked particles cannot be controlled, so that amino resin crosslinked particles having a wide particle size distribution may be obtained.

  As a stirring method in the mixing step, a general stirring method may be adopted. For example, a stirring method using stirring blades such as a disk turbine, a fan turbine, a fowler type, a propeller type, and a multistage blade is preferable.

  In the second production method, in order to prevent the finally obtained amino resin crosslinked particles from agglomerating firmly, if necessary, inorganic particles are added to the mixed liquid obtained after the mixing step. It may be left. Regarding the inorganic particles and the addition method thereof, the description in the first production method described above can be similarly applied.

  In the curing and granulating step, a catalyst (specifically a curing catalyst) is added to the mixed solution prepared in the above mixing step, the amino resin precursor is cured and granulated, and amino resin crosslinked particles (specifically, the amino resin) A suspension of cross-linked particles).

  As the catalyst (curing catalyst), an acid catalyst is suitable. As the acid catalyst, those similar to those exemplified in the first production method are preferably used. In the second production method, in particular, alkylbenzenesulfonic acid having an alkyl group having 10 to 18 carbon atoms is used. preferable. Alkylbenzenesulfonic acid having an alkyl group having 10 to 18 carbon atoms exhibits unique surface activity in an aqueous liquid of the amino resin precursor as the initial condensate, and generates a stable suspension of the cured resin. . Specifically, for example, decylbenzenesulfonic acid, dodecylbenzenesulfonic acid, tetradecylbenzenesulfonic acid, hexadecylbenzenesulfonic acid, octadecylbenzenesulfonic acid and the like can be mentioned. These may be used alone or in combination of two or more.

  It is preferable that the usage-amount of the said catalyst is 0.1-20 mass parts with respect to 100 mass parts of amino resin precursors in the liquid mixture obtained by the said mixing process, More preferably, it is 0.5-10. It is 1-10 mass parts, More preferably, it is 1-10 mass parts. When the amount of the catalyst used is less than the above range, it takes a long time for condensation and curing, and a stable suspension of amino resin crosslinked particles cannot be obtained. There is a possibility that it can be obtained only in the state of inclusion. On the other hand, if the amount exceeds the above range, the catalyst such as alkylbenzene sulfonic acid will be distributed more than necessary in the amino resin crosslinked particles in the resulting suspension. As a result, the amino resin crosslinked particles are plasticized. Thus, aggregation and fusion between particles are likely to occur during condensation curing, and there is a possibility that the amino resin crosslinked particles having a uniform particle diameter may not be finally obtained.

  Similarly, the amount of the catalyst used is preferably 0.0005 mol or more, more preferably 0.002 mol or more, and still more preferably 0 with respect to 1 mol of the amino compound used as the raw material compound. 0.005 to 0.05 mole. When the amount of the catalyst used is less than 0.0005 mol with respect to 1 mol of the amino compound, the reaction may take a long time or the curing may be insufficient.

  The curing reaction and particle formation in the curing / particulation process are carried out by adding the above catalyst to the amino resin precursor mixture and stirring at an appropriate temperature from a low temperature of 0 ° C. to a high temperature of 100 ° C. or higher under pressure. You can hold it. There is no restriction | limiting in particular in the addition method of the said catalyst, It can select suitably. The end point of the curing reaction may be judged by sampling or visual observation. Further, the reaction time of the curing reaction is not particularly limited. The curing reaction is generally completed by raising the temperature to 90 ° C. or higher and holding it for a certain period of time. However, curing at a high temperature is not necessarily required, and the suspension obtained even at a low temperature for a short time. It is sufficient if the amino resin crosslinked particles in the liquid are cured to such an extent that they do not swell with methanol or acetone.

  It is preferable to perform a hardening and granulation process under stirring with a well-known stirring apparatus etc. normally. The average particle diameter of the preferred amino resin crosslinked particles is the same as that of the average particle diameter of the amino resin crosslinked particles in the curing step of the first production method.

  In the 2nd manufacturing method, the neutralization process of neutralizing the suspension containing the amino resin bridge | crosslinking particle | grains obtained by the said hardening process can be included. For details such as the pH range and the type of the neutralizing agent in the neutralization step, the description in the first production method can be similarly applied.

  In the second production method, a separation step of taking out the amino resin crosslinked particles from the suspension of amino resin crosslinked particles obtained after the curing / particulating step or the neutralizing step may be provided. In the second production method, separating the amino resin crosslinked particles from the suspension means removing the amino resin crosslinked particles obtained by curing from the aqueous medium in the mixing step. As a method (separation method) for taking out the amino resin crosslinked particles from the suspension, a method similar to the first production method can be applied.

  In the second production method, it is preferable to perform a heating step of heating the amino resin crosslinked particles taken out through the separation step at a temperature of 130 to 190 ° C. As conditions for the heating step, the same conditions as those for the heating step of the first manufacturing method can be applied.

  The amino resin crosslinked particles obtained by the second production method are separated from the aqueous medium at the time of the mixing step or at the time of curing and granulating, dried and pulverized, and then the pulverized product obtained is mixed with a solvent. It is preferable to form a suspension, wet-classify, separate and dry, and then dry-classify. It is preferable to supply the suspension after the curing and granulating step, or the suspension subjected to the neutralization step / water washing step to wet and dry classification. After wet classification, it is preferable to separate the particles, and if necessary, dry and pulverize them through a heating step to form fine powder particles having a moisture content of 0.05 to 2% by mass, and then dry classification.

  Next, the structure and manufacturing method of the fine particles (the above (C)) made of organic-inorganic composite material will be described. There is no particular limitation on the method for polymerizing the fine particles of the organic / inorganic composite material, and known polymerization methods such as emulsion polymerization, suspension polymerization, seed polymerization, and sol-gel polymerization can be applied.

  As described above, fine particles made of an organic-inorganic composite material (hereinafter referred to as composite particles) are particles comprising an organic polymer skeleton as an organic part and a polysiloxane skeleton as an inorganic part. The composite particle has a form (chemical bond type) in which an organic silicon atom in which a silicon atom in a polysiloxane skeleton is directly chemically bonded to at least one carbon atom in the organic polymer skeleton is included in the molecule. Is preferred. As a specific form, the silicon atom in the polysiloxane skeleton and the carbon atom in the organic polymer skeleton are bonded, so that the polysiloxane skeleton and the organic polymer skeleton form a three-dimensional network structure. The form is preferred.

  The organic polymer skeleton may have a side chain, a branched structure, or a crosslinked structure. There are no particular limitations on the molecular weight, composition, structure, presence or absence of functional groups, and the like of the organic polymer forming the skeleton. Examples of the organic polymer include (meth) acrylic resins, vinyl polymers such as polystyrene and polyolefin, polyamides such as nylon, polyimide, polyester, polyether, polyurethane, polyurea, polycarbonate, phenol resin, melamine resin, and urea. It is preferably at least one selected from the group consisting of resins.

  As the form of the organic polymer skeleton, the following formula (1):

It is preferable that it is a polymer (what is called a vinyl polymer) which has the principal chain comprised by the repeating unit represented by these.

  The polysiloxane skeleton has the following formula (2):

Is defined as a compound in which a network having a network structure is formed by continuous chemical bonding. The amount of SiO ₂ constituting the polysiloxane skeleton is preferably 0.1 to 25% by mass, more preferably 1 to 10% by mass with respect to the weight of the composite particles. When the amount of SiO ₂ in the polysiloxane skeleton is in the above range, the hardness of the composite particles can be easily controlled. Further, if it is less than 0.1% by mass, the flexibility and elasticity of the particles are lowered, and there is a possibility that problems such as destruction of the inside of the particles occur when external stress is applied to the resin composition. If it exceeds 1, the adhesion between the particles and the resin is lowered, and the particles in the resin composition may easily fall off. The amount of SiO ₂ constituting the polysiloxane skeleton is a mass percentage obtained by measuring the mass before and after firing the particles at a temperature of 800 ° C. or higher in an oxidizing atmosphere such as air.

The composite particle has a ratio of the number of carbon atoms and the number of silicon atoms (surface atom number ratio (C / Si)) of 1.0 to 1.0 × 10 ⁴ determined by photoelectron spectroscopy. It is preferable in terms of excellent adhesion to the resin when used in a resin. If the surface atom number ratio (C / Si) is less than 1.0, the adhesion to the resin may be lowered. If it exceeds 1.0 × 10 ⁴ , the flexibility and elasticity of the particles are increased. When the external stress is applied to the resin composition, there is a risk that the inside of the particle breaks down.

  The composite particles can be arbitrarily adjusted by appropriately changing the ratio of the polysiloxane skeleton portion or the organic polymer skeleton portion with respect to each of mechanical properties such as hardness and breaking strength.

  The polysiloxane skeleton in the composite particles is preferably obtained by a hydrolysis condensation reaction of a silicon compound having a hydrolyzable group.

Although it does not specifically limit as a silicon compound which has hydrolyzability, For example, following General formula (3):
R'mSiX _4-m (3)
(Here, R ′ may have a substituent, and represents at least one group selected from the group consisting of an alkyl group, an aryl group, an aralkyl group and an unsaturated aliphatic group, and X represents a hydroxyl group, an alkoxy group. And at least one group selected from the group consisting of a group and an acyloxy group, and m is an integer from 0 to 3.).

  The silicon compound represented by the general formula (3) is not particularly limited, but examples of m = 0 include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, and the like. Functional silanes: those with m = 1 include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, hexyltrimethoxysilane, decyltrimethoxysilane, phenyltrimethoxysilane, benzyltrimethoxy Silane, naphthyltrimethoxysilane, methyltriacetoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltrimethoxysilane, 3- (meth) acryloxyp Trifunctional silanes such as pyrtrimethoxysilane and 3,3,3-trifluoropropyltrimethoxysilane; m = 2 include dimethyldimethoxysilane, dimethyldiethoxysilane, diacetoxydimethylsilane, diphenylsilanediol, etc. Examples of the bifunctional silane: m = 3 include monofunctional silanes such as trimethylmethoxysilane, trimethylethoxysilane, and trimethylsilanol.

  Among these, in the general formula (3), a silane compound in which m has a structure of 1, X is a methoxy group or an ethoxy group, and a refractive index is 1.30 to 1.60 is used for optical applications. This is preferable because organic-inorganic composite particles having a suitable refractive index can be obtained. Specifically, methyltrimethoxysilane, phenyltrimethoxysilane, 3- (meth) acryloxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3,3,3-trifluoro And propyltrimethoxysilane.

  The derivative of the silicon compound represented by the general formula (3) is not particularly limited. For example, a part of X is substituted with a group capable of forming a chelate compound such as a carboxyl group and a β-dicarbonyl group. And low condensates obtained by partially hydrolyzing the silane compound.

  Only one type of silicon compound having hydrolyzability may be used, or two or more types may be used in appropriate combination. In the above general formula (3), when only the silane compound and its derivative with m = 3 are used as raw materials, composite particles cannot be obtained.

  When the composite particle has a form in which the polysiloxane skeleton has an organic silicon atom in which a silicon atom is directly bonded to at least one carbon atom in the organic polymer skeleton, the hydrolyzable silicon compound. It is necessary to use those having an organic group containing a polymerizable reactive group capable of forming an organic polymer skeleton. Examples of the reactive group include a radical polymerizable group, an epoxy group, a hydroxyl group, and an amino group. Can be mentioned.

Examples of the organic group containing the radical polymerizable group include the following general formulas (4), (5), and (6):
^{_{CH 2 = C (-R a)}} -COOR b - (4)
(Here, R ^a represents a hydrogen atom or a methyl group, and R ^b represents a C 1-20 divalent organic group which may have a substituent.)
^{_{CH 2 = C (-R c)}} - (5)
(Here, R ^c represents a hydrogen atom or a methyl group.)
^{_{CH 2 = C (-R d)}} -R e - (6)
(Here, R ^d represents a hydrogen atom or a methyl group, and R ^e represents a C 1-20 divalent organic group which may have a substituent.)
And the like, and the like.

  Examples of the radical polymerizable group-containing organic group of the general formula (4) include an acryloxy group and a methacryloxy group. Examples of the silicon compound of the general formula (3) having the organic group include γ- Methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-acryloxypropyltriethoxysilane, γ-methacryloxypropyltriacetoxysilane, γ-methacryloxyethoxypropyltri Methoxysilane (or γ-trimethoxysilylpropyl-β-methacryloxyethyl ether), γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-acryloxypropylmethyl Examples thereof include rudimethoxysilane. These may be used alone or in combination of two or more.

  Examples of the radical polymerizable group-containing organic group of the general formula (5) include a vinyl group and an isopropenyl group. Examples of the silicon compound of the general formula (3) having the organic group include vinyl. Examples include trimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, and vinylmethyldiacetoxysilane. These may be used alone or in combination of two or more. Examples of the radical polymerizable group-containing organic group of the general formula (6) include a 1-alkenyl group or a vinylphenyl group, an isoalkenyl group, an isopropenylphenyl group, and the like. Examples of the silicon compound 3) include 1-hexenyltrimethoxysilane, 1-hexenyltriethoxysilane, 1-octenyltrimethoxysilane, 1-decenyltrimethoxysilane, γ-trimethoxysilylpropyl vinyl ether, ω- Examples include trimethoxysilylundecanoic acid vinyl ester, p-trimethoxysilylstyrene (p-styryltrimethoxysilane), 1-hexenylmethyldimethoxysilane, 1-hexenylmethyldiethoxysilane, and the like. These may be used alone or in combination of two or more.

  Examples of the silicon compound having an organic group containing an epoxy group include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, β- ( 3,4-epoxycyclohexyl) ethyltrimethoxysilane and the like. These may be used alone or in combination of two or more. Examples of the silicon compound having an organic group containing a hydroxyl group include 3-hydroxypropyltrimethoxysilane. These may be used alone or in combination of two or more.

  Examples of the silicon compound having an organic group containing an amino group include N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β ( Aminoethyl) γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, and the like. These may be used alone or in combination of two or more.

  The organic polymer skeleton contained in the composite particle is, for example, 1) a polymerizable reactive group capable of forming an organic polymer skeleton such as a radical polymerizable group and an epoxy group together with the hydrolyzable group. In the case of having an organic group to be contained, 1-1) a method of polymerizing after a hydrolytic condensation reaction of a silicon compound, or 1-2) particles having a polysiloxane skeleton obtained by a hydrolytic condensation reaction of a silicon compound, It can also be obtained by a method in which a polymerizable monomer having a polymerizable reactive group such as a radical polymerizable monomer, a monomer having an epoxy group, a monomer having a hydroxyl group, and a monomer having an amino group is absorbed and then polymerized. 2) If the silicon compound does not have an organic group containing a polymerizable reactive group capable of forming an organic polymer skeleton such as a radical polymerizable group, an epoxy group, a hydroxyl group, or an amino group, Particles having a polysiloxane skeleton obtained by decomposition condensation reaction (seed particles made of polysiloxane particles, hereinafter also referred to as polysiloxane particles) are combined with radically polymerizable monomers, monomers having epoxy groups, monomers having hydroxyl groups, and amino groups. It can also be obtained by absorbing a polymerizable monomer having a polymerizable reactive group such as a monomer having the polymerization reaction.

  As described above, the composite particles have a) a form in which a polysiloxane skeleton has an organic silicon atom in a molecule in which a silicon atom is directly chemically bonded to at least one carbon atom in the organic polymer skeleton (chemical bond type). B) may have a form (IPN type) that does not have such an organosilicon atom in the molecule, and is not particularly limited. For example, as in 1-1) above When the organic polymer skeleton is obtained together with the polysiloxane skeleton, a composite particle having the form of a) can be obtained, and in the case of 2), the composite particle having the form of b) can be obtained. . When the organic polymer skeleton is obtained together with the polysiloxane skeleton as in 1-2) above, composite particles having a form having both the forms of a) and b) are obtained.

  In the above methods 1-2) and 2), the radical polymerizable monomer that can be absorbed by the particles having a polysiloxane skeleton is preferably a monomer component that essentially includes a radical polymerizable vinyl monomer. The radical polymerizable vinyl monomer is not particularly limited as long as it is a compound containing at least one ethylenically unsaturated group in the molecule, depending on the desired physical properties of the composite particles. It can be selected appropriately. These may be used alone or in combination of two or more.

  For example, a hydrophobic radical-polymerizable vinyl monomer is preferable because a stable emulsion in which the monomer component is emulsified and dispersed can be generated when the monomer component is absorbed by particles having a polysiloxane skeleton. Further, as the radical polymerizable vinyl monomer, a crosslinkable monomer may be used. If the crosslinkable monomer is used, the mechanical properties of the obtained composite particles can be easily adjusted, and the solvent resistance of the composite fine particles can be adjusted. It can also improve the performance. Specific examples include ethylene glycol dimethacrylate, trimethylolpropane trimethyl acrylate, 1,6-hexanediol diacrylate, and divinylbenzene. These may be used alone or in combination of two or more.

  As a method for producing the composite particles, a production method including a hydrolysis and condensation step, which will be described later, and a polymerization step is preferably exemplified. Furthermore, if necessary, an absorption step for absorbing the polymerizable monomer may be included after the hydrolysis and condensation step and before the polymerization step (in the case of the above 1-2) and 2). In addition, when the silicon compound used in the hydrolysis and condensation process does not have an element that constitutes an organic polymer skeleton together with an element that can constitute a polysiloxane skeleton structure (in the case of 2), the absorption process is essential. And an organic polymer skeleton is formed in the polymerization step following the absorption step.

  The hydrolysis and condensation steps are steps in which the above-described silicon compound is hydrolyzed in a solvent containing water to undergo condensation polymerization. By this step, particles having a polysiloxane skeleton (polysiloxane particles) can be obtained. Hydrolysis and polycondensation can employ any method such as batch, split or continuous. In the hydrolysis and condensation polymerization, basic catalysts such as ammonia, urea, ethanolamine, tetramethylammonium hydroxide, alkali metal hydroxide, and alkaline earth metal hydroxide can be preferably used as the catalyst.

  In the solvent containing water, an organic solvent can be contained in addition to water and the catalyst. Examples of the organic solvent include alcohols such as methanol, ethanol, isopropanol, n-butanol, isobutanol, sec-butanol, t-butanol, pentanol, ethylene glycol, propylene glycol, 1,4-butanediol; acetone, Examples thereof include ketones such as methyl ethyl ketone; esters such as ethyl acetate; (cyclo) paraffins such as isooctane and cyclohexane; aromatic hydrocarbons such as benzene and toluene. These may be used alone or in combination of two or more.

  In the hydrolysis and condensation step, anionic, cationic and nonionic surfactants and polymer dispersants such as polyvinyl alcohol and polyvinylpyrrolidone can be used in combination. These may be used alone or in combination of two or more.

  In the hydrolysis and condensation, the silicon compound as a raw material is mixed with a solvent containing a catalyst, water and an organic solvent, and then stirred at a temperature of 0 to 100 ° C., preferably 0 to 70 ° C., for 30 minutes to 100 hours. Can be performed. Alternatively, after producing particles by performing hydrolysis and condensation reactions to a desired degree, the seed particles may be grown by adding silicon compounds to the reaction system as seed (seed) particles.

  The polysiloxane particles preferably have a weight average molecular weight of 250 to 10,000, more preferably 250 to 5,000. If the weight average molecular weight is within the above range, the absorption rate of the polymerizable monomer in the absorption step is high, and the generation of coarse particles derived from the polymerizable monomer remaining without being absorbed in the system is suppressed. A composite particle having a coarse particle content that is twice or more the average particle diameter or a fine particle content in the composite particle (used for dry classification) is obtained. Furthermore, by subjecting the composite particles to wet classification and dry classification steps, particles with extremely low coarse particle content can be obtained in high yield.

  As described above, the absorption process may be an essential process depending on the silicon compound to be used, or may be an optional process. The absorption process is not particularly limited as long as it proceeds in the presence of a polymerizable monomer in the presence of polysiloxane particles. Therefore, the polymerizable monomer may be added to the solvent in which the polysiloxane particles are dispersed, or the polysiloxane particles may be added to the solvent containing the polymerizable monomer. In particular, as in the former case, it is preferable to add a polymerizable monomer in a solvent in which polysiloxane particles are dispersed in advance. Furthermore, the polysiloxane particles obtained in the hydrolysis and condensation steps are reacted with a reaction solution (polysiloxane). A method of adding a polymerizable monomer to the reaction liquid without taking it out from the particle dispersion) is preferable because the process is not complicated and the productivity is excellent.

  In the absorption step, the polymerizable monomer is absorbed in the structure of the polysiloxane particles, but the concentration of each of the polysiloxane particles and the polymerizable monomer is increased so that the absorption of the polymerizable monomer proceeds promptly. It is preferable to set the mixing ratio of the polysiloxane and the polymerizable monomer, the processing method and means for mixing, the temperature and time at the time of mixing, the processing method and means after mixing, and the like, and performing under the conditions. The necessity of these conditions may be appropriately considered depending on the type of polysiloxane particles and polymerizable monomers used. These conditions may be applied singly or in combination of two or more.

  In the absorption step, the addition amount of the polymerizable monomer is preferably 0.01 to 100 times by mass with respect to the mass of the silicon compound used as the raw material for the polysiloxane particles. More preferably, it is 0.5-50 times, More preferably, it is 0.5-30 times, Especially preferably, it is 1-15 times. If the addition amount is less than the above range, the amount of the polymerizable monomer of the polysiloxane particles is reduced, it may be difficult to obtain the mechanical properties of the composite particles to be produced. There is a tendency that it is difficult to completely absorb the added polymerizable monomer into the polysiloxane particles, and the unabsorbed polymerizable monomer remains, causing aggregation between the particles in the later polymerization stage, or unabsorbed polymerization. There is a possibility that coarse particles derived from the functional monomer are likely to be generated.

  In the above absorption step, the timing of addition of the polymerizable monomer is not particularly limited, and the polymerizable monomer may be added all at once, may be added in several times, or fed at an arbitrary rate. May be. In addition, when adding the polymerizable monomer, it may be added only with the polymerizable monomer, or a solution of the polymerizable monomer may be added. However, the polymerizable monomer is preliminarily emulsified and dispersed with an emulsifier in the polysiloxane particles. It is preferable to add it because the absorption to the polysiloxane particles is performed more efficiently.

  The emulsifier is not particularly limited. For example, an anionic surfactant, a cationic surfactant, a nonionic surfactant, an amphoteric surfactant, a polymer surfactant, and one or more polymerizable molecules in the molecule. Examples include polymerizable surfactants having a carbon-carbon unsaturated bond. Among these, anionic surfactants and nonionic surfactants are preferable because they can stabilize the dispersion state of polysiloxane particles, polysiloxane particles that have absorbed a polymerizable monomer, and polymer fine particles. These emulsifiers may be used alone or in combination of two or more.

  The usage-amount of the said emulsifier is not specifically limited, Specifically, it is preferable that it is 0.01-10 mass% with respect to the total mass of the said polymerizable monomer, More preferably, it is 0.05-8. It is 1 mass%, More preferably, it is 1-5 mass%. When the amount of the emulsifier used is less than 0.01% by mass, a stable polymerizable monomer emulsion dispersion may not be obtained. When the amount exceeds 10% by mass, emulsion polymerization or the like occurs as a side reaction. There is a risk of it. About the said emulsification dispersion | distribution, it is preferable to usually make the said polymerizable monomer into an emulsion state in water using a homomixer, an ultrasonic homogenizer, etc. with an emulsifier.

  Moreover, when emulsifying and dispersing the polymerizable monomer with an emulsifier, it is preferable to use water or a water-soluble organic solvent 0.3 to 10 times the mass of the polymerizable monomer. Examples of the water-soluble organic solvent include alcohols such as methanol, ethanol, isopropanol, n-butanol, isobutanol, sec-butanol, t-butanol, pentanol, ethylene glycol, propylene glycol, 1,4-butanediol; acetone And ketones such as methyl ethyl ketone; esters such as ethyl acetate;

  The absorption step is preferably performed in the temperature range of 0 to 60 ° C. with stirring for 5 minutes to 720 minutes. These conditions may be set as appropriate depending on the type of polysiloxane particles and polymerizable monomers used, and these conditions may be used alone or in combination of two or more.

  In the absorption process, for determining whether or not the monomer component is absorbed by the polysiloxane particles, for example, before adding the monomer component and after the absorption step, the particles are observed with a microscope, and the particle diameter increases due to absorption of the monomer component. It can be easily judged by confirming that

  The polymerization step is a step of obtaining particles having an organic polymer skeleton by polymerizing a polymerizable reactive group. Specifically, when a silicon compound having a polymerizable reactive group-containing organic group is used, it is a step of polymerizing a polymerizable reactive group of the organic group to form an organic polymer skeleton, which has undergone an absorption step. Is a step of polymerizing a polymerizable monomer having a polymerizable reactive group that has been absorbed to form an organic polymer skeleton, but in both cases, it can be a step of forming an organic polymer skeleton by either reaction. .

  The polymerization reaction may be performed in the middle of the hydrolysis-condensation step or the absorption step, and may be performed after either or both of the steps, and is not particularly limited, but usually after the hydrolysis-condensation step (the absorption step). If so, start after the absorption step).

  The polymerization reaction is not particularly limited. For example, any of a method using a radical polymerization initiator, a method of irradiating ultraviolet rays or radiation, a method of applying heat, and the like can be adopted. The radical polymerization initiator is not particularly limited, but examples thereof include persulfates such as potassium persulfate, hydrogen peroxide, peracetic acid, benzoyl peroxide, lauroyl peroxide, orthochlorobenzoyl peroxide, orthomethoxybenzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, t-butylperoxy-2-ethylhexanoate, di-t-butyl peroxide, benzoyl peroxide, 1,1-bis (t-butylperoxy)- Peroxide initiators such as 3,3,5-trimethylcyclohexane and t-butyl hydroperoxide; azobisisobutyronitrile, azobiscyclohexacarbonitrile, azobis (2,4-dimethylvaleronitrile), 2'-azobisisobutyronitrile, 2,2'-azobis (2-amidino Lopan) dihydrochloride, 4,4′-azobis (4-cyanopentanoic acid), 2,2′-azobis- (2-methylbutyronitrile), 2,2′-azobisisobutyronitrile, 2 Preferred examples include azo compounds such as 2,2′-azobis (2,4-dimethylvaleronitrile). These radical polymerization initiators may be used alone or in combination of two or more.

  The amount of the radical polymerization initiator used is preferably 0.001% by mass to 20% by mass, more preferably 0.01% by mass to 10% by mass, further based on the total mass of the polymerizable monomer. Preferably it is 0.1 mass%-5 mass%. When the usage-amount of the said radical polymerization initiator is less than 0.001 mass%, the polymerization degree of a polymerizable monomer may not rise. The method of charging the radical polymerization initiator into the solvent is not particularly limited, and is a method in which the entire amount is initially charged (before starting the reaction) (a mode in which the radical polymerization initiator is emulsified and dispersed together with the polymerizable monomer, the polymerizable monomer is A mode in which a radical polymerization initiator is charged after absorption); a method in which a part is initially charged and the rest is continuously fed, a pulse is intermittently added, or a combination of these is conventionally used Any known method can be employed.

  The reaction temperature for the radical polymerization is preferably 40 to 100 ° C, more preferably 50 to 80 ° C. If the reaction temperature is too low, the degree of polymerization does not increase sufficiently and the mechanical properties of the polymer fine particles tend to be difficult to obtain. On the other hand, if the reaction temperature is too high, aggregation between particles occurs during the polymerization. Tends to occur. In addition, what is necessary is just to change suitably the reaction time at the time of the said radical polymerization according to the kind of polymerization initiator to be used, Usually, 5-600 minutes are preferable and 10-300 minutes are more preferable. When the reaction time is too short, the degree of polymerization may not be sufficiently increased, and when the reaction time is too long, aggregation tends to occur between particles.

  In the present invention, after the polymerization step, the prepared liquid containing the polymer fine particles is used as it is or after the organic solvent is distilled and replaced with a dispersion medium containing water and / or alcohol and then supplied to the wet classification step. Alternatively, the produced polymer fine particles may be isolated and dried, then dispersed in water and / or an organic solvent, and then supplied to the wet classification step.

  Since the fine particles of the present invention have a reduced content of coarse particles and fine particles and a narrow particle size distribution, the light diffusion sheet and light guide plate used in optical applications such as LCDs, or PDPs, EL displays and It is useful as an additive such as a light diffusing agent or an antiblocking agent contained in an optical resin used for a touch panel or the like. Of course, it is also suitably used as an anti-blocking agent for various films other than these optical uses.

  The resin composition according to the present invention is a resin composition containing the fine particles of the present invention and a transparent binder resin. As described above, the fine particles of the present invention are suitably used for optical applications because the content of fine particles as well as coarse particles is suppressed to an extremely low level.

  The content of the fine particles in the resin composition may be appropriately determined according to the application and desired optical properties, but if used for optical applications, 1 part by mass with respect to 100 parts by mass of the binder resin composition. As mentioned above, it is preferable to set it as 300 mass parts or less. More preferably, it is 2 mass parts or more, More preferably, it is 5 mass parts or more, More preferably, it is 200 mass parts or less, More preferably, it is 150 mass parts or less. If the content of the fine particles is too large, the strength of the optical member may be reduced. If the content is too small, it may be difficult to obtain the expected effects (such as light diffusibility) by adding the fine particles.

  The transparent binder resin contained in the resin composition of the present invention is not particularly limited, and any of those used as a binder resin in this field can be used. For example, (I) When the member formed using the resin composition of the present invention is formed by molding the resin composition of the present invention into a desired shape such as a plate or sheet (that is, a binder) As the transparent resin, polyester resin such as polyethylene terephthalate and polyethylene naphthalate, acrylic resin, polystyrene resin, polycarbonate resin, polyethersulfone resin, polyurethane Resins, polysulfone resins, polyether resins, polymethylpentene resins, polyether ketone resins, (meth) acrylonitrile resins, polyolefin resins such as polypropylene resins, norbornene resins, amorphous polyolefin resins, polyamide resins, polyimide resins, And triacetyl acetate Such as loin resin and the like.

  Moreover, (II) When the member is formed by laminating (coating, laminating, etc.) the resin composition of the present invention on a previously prepared plate-like or sheet-like substrate surface As the transparent binder resin, the same binder resin as described above can be used. For example, acrylic resin, polypropylene resin, polyvinyl alcohol resin, polyvinyl acetate resin, polystyrene resin, polyvinyl chloride resin, silicon resin, and polyurethane resin. And polyester resins.

  In addition to the fine particles and the transparent binder resin, the resin composition of the present invention may contain other components as necessary as long as the effects of the present invention are not impaired. Examples of other components include a curing agent, a crosslinking agent, various additives and stabilizers, a flame retardant, an antioxidant, and an ultraviolet absorber in order to improve physical properties such as light resistance and UV resistance. These may use only 1 type and may use 2 or more types together.

  Since the molded product obtained from the resin composition of the present invention is a molded product in which the fine particles of the present invention are dispersed and fixed in the binder resin, it has excellent optical properties such as light diffusibility and light transmittance. It is. Therefore, the resin composition of the present invention is suitably used as a raw material for constituent members of various optical products. From the viewpoint of effectively utilizing the excellent light diffusibility and light transmission derived from the fine particles of the present invention described above, it is installed in front of various image display devices to reflect external light and indoor lighting equipment. Anti-glare anti-glare film for preventing image deterioration and image members such as light diffusing film and light diffusing plate for uniformly diffusing light from the light source to the image display surface in the image display device Is preferably used.

  The shape of the optical member is not limited to a film shape (sheet shape) or a plate shape, and may be formed into a desired shape such as a column, a cone, or a sphere. From the viewpoint of securing an excellent light diffusion effect and antiglare effect (antiglare effect by suppressing regular reflection of light and diffusing), the surface of the optical member is derived from the fine particles of the present invention described above. It is preferable that irregularities to be formed are formed.

  For example, when the optical member is a film-like molded body (hereinafter referred to as “optical film”) such as a light diffusion film or an antireflection antiglare film, the form thereof has a planar portion. A configuration in which the light diffusion particles are fixed by a transparent binder resin (optical functional layer) is included in at least a part. For example, (i) a transparent binder resin itself that constitutes the resin composition is used as a base resin such as a plate or sheet, and is formed into a plate or film (such as a light diffusion plate); (ii) prepared in advance Layers made of the above resin composition are laminated (coating, laminating) on a part or the whole of the surface of a plate-like or sheet-like base material, and an integrated form (light-diffusing film, anti-glare film such as an antiglare film) , Light diffusing plate, etc.). In any of the above forms (i) and (ii), since the particles are dispersed and fixed in the transparent binder resin, excellent optical properties can be exhibited.

  The above-mentioned “having a planar portion” generally means a substantially flat surface portion having a certain area spread such that the shape of the optical member is plate, sheet or film. (Including the case where fine irregularities are formed on the surface) is the main component of the shape, but in the present invention is not limited to such an aspect, even if it is not the main component, It is only necessary that at least a part of the shape has a substantially flat surface portion.

  Examples of the method for producing the optical member of the form (i) include a method in which the resin composition of the present invention is extruded while being melt-kneaded by a known extruder and molded into a sheet shape, a plate shape, and a film shape. . At this time, in order to enhance physical properties such as light resistance and UV resistance, additives such as various additives, stabilizers and flame retardants may be added to the resin composition as necessary. In order to obtain a molded article having uniform optical properties, the resin composition is preferably mixed and dispersed in advance with the fine particles of the present invention in a transparent binder resin. Similarly, the additive may be mixed with the resin composition.

  Examples of the method for obtaining the optical member in the form (ii) include a method of laminating a layer made of the resin composition of the present invention on a previously prepared base material surface. The lamination method is not particularly limited, and preferred examples include a coating method and a casting method. As a coating method, a coating composition comprising the resin composition may be applied to a substrate. The resin composition of the present invention can be used as a coating composition as it is. However, the resin composition may be used as water or an organic solvent (for example, an alcohol solvent such as methanol, ethanol, isopropanol, ethylene glycol, propylene). It is preferable to use a coating composition prepared by dispersing and dissolving in a ketone solvent such as glycol, an ester solvent such as ethyl acetate, and an aromatic hydrocarbon such as toluene and xylene. Although a base material is not specifically limited, For example, conventionally well-known colorless and transparent resin films, such as a polyolefin-type resin film, a polyester-type resin film, a polycarbonate-type resin film, are used preferably. Specific coating methods include known laminating methods such as reverse roll coating, gravure coating, die coating, comma coating, and spray coating.

  After coating, the solvent contained in the coating film is dried as necessary, and then the coating film is solidified to form a resin composition layer. From the viewpoint of ensuring heat resistance and weather resistance, the layer made of the resin composition is preferably cured or crosslinked with the binder resin contained in the resin composition.

  The film thickness of the layer made of the resin composition (or coating composition) of the present invention formed by the method described above is not particularly limited, but in the case of the light diffusion film, the layer made of the resin composition (light diffusion layer) In the case of an anti-glare film, the thickness of the layer made of the resin composition (anti-glare layer) is preferably 20 μm or less, and the thickness of the light diffusion plate is preferably 2000 μm or less. Conventionally, when the thickness is thin, it has been difficult to develop sufficient light diffusibility and light transmittance. However, if the fine particles or the resin composition of the present invention is used, it is extremely excellent even if the thickness is small. Light diffusibility and light transmittance can be exhibited. In addition, the value of the said light-diffusion film and anti-glare film film thickness represents the thickness of the layer (namely, light-diffusion layer, anti-glare layer) containing the resin composition laminated | stacked on the base material. The thickness of is not included.

  In the fine particles of the present invention, the content of coarse particles is suppressed to an extremely low level, and in addition to having a sharp particle size distribution, the chemical composition hardly undergoes alteration such as swelling in the coating composition. Therefore, uniform and fine irregularities can be formed on the optical member as described above (light diffusion film, antiglare film, light diffusion plate, etc.). Therefore, optical members such as a light diffusion film, an antiglare film and a light diffusion plate obtained by using the fine particles of the present invention are optical foreign matters that cause local glare from the coarse particles and appearance defects. Is unlikely to occur. Further, since the optical characteristics can be adjusted by controlling the average particle size of the fine particles of the present invention, it is suitably used for optical applications.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. It is also possible to implement, and they are all included in the technical scope of the present invention. Unless otherwise specified, mass parts may be expressed as “parts” and mass% as “%”.

Production of fine particles Production Example 1 (polysiloxane fine particles)
A mixed solution of 280 parts of ion-exchanged water, 5 parts of 25% aqueous ammonia and 120 parts of methanol is placed in a reaction kettle equipped with a cooling device, a thermometer and a dropping port, and γ-methacrylic acid is added from the dropping port while stirring the mixed solution. 40 parts of roxypropyltrimethoxysilane was added, and γ-methacryloxypropyltrimethoxysilane was hydrolyzed and condensed at a temperature of 30 ° C. for 2 hours to prepare a suspension of polysiloxane fine particles. The weight average molecular weight of the polysiloxane particles obtained at this time was 1800 (corresponding to about a 7-mer of the used silicon compound).

  Separately, in a reaction vessel 2 different from the above, 400 parts of styrene, 3 parts of 2,2′-azobis (2,4-dimethylvaleronitrile) (manufactured by Wako Pure Chemical Industries, Ltd., V-65), anionic interface An emulsion (monomer solution) was prepared by emulsifying and dispersing 1.5 parts of an activator (LA-10, manufactured by Daiichi Kogyo Co., Ltd.) and 400 parts of ion-exchanged water with a homomixer at room temperature (25 ° C.) for 15 minutes.

  Two hours after the start of preparation of the suspension of polysiloxane particles (two hours after the addition of γ-methacryloxypropyltrimethoxysilane), the emulsion was added from the dropping port of the reaction vessel 1. After stirring for 1 hour and confirming that the polysiloxane particles have absorbed the monomer component, 3500 parts of ion-exchanged water is added thereto, and the reaction solution is heated to 65 ° C. under a nitrogen atmosphere. The mixture was held at 65 ± 2 ° C. for 2 hours, and a radical polymerization reaction was performed to obtain a polymer particle (organic-inorganic composite particle) dispersion. The average particle diameter of the polymer particles dispersed in the dispersion is 10.1 μm, the B-type viscosity of the dispersion (B-type viscometer, manufactured by Tokyo Keiki Co., Ltd.) is 3.8 mPa · s, and the solid content concentration is 10% by mass. Met.

Production Examples 2 to 7 (polysiloxane particles)
A polymer particle dispersion was prepared in the same manner as in Production Example 1, except that the polysiloxane particle raw material, the radical polymerizable monomer species, and the amount used were changed as shown in Table 1. In addition, the amount of ion-exchange water, methanol, and surfactant used for adjusting the polysiloxane particle suspension and emulsion was appropriately adjusted according to the conditions of each production example.

[Measurement of average particle diameter and amount of coarse particles of polymer particles]
The polymer particle dispersion obtained in the above production example is subjected to solid-liquid separation, and 0.5 g of dried polymer particles are dispersed in 100 g of ion-exchanged water to prepare a polymer particle dispersion. Using the product name “Multisizer II” (manufactured by Beckman Coulter, Inc.), the particle size of the polymer particles was measured, and the average particle size was calculated on a volume basis.

  Note that the amount of coarse particles (coarse particles having a particle size of twice or more the average particle size) contained in the polymer particle dispersion was measured as follows.

  A polymer particle dispersion solution (viscosity: 3 mPa · s, solid content concentration: 0.5% by mass) in which 0.5 g of dried polymer particles are dispersed in 100 g of methanol is prepared, and the average particle diameter is 1.75 to 1. Filtration was performed under reduced pressure using a mesh having a double opening (made of nickel, manufactured by Tokyo Process Service Co., Ltd.) and a suction filtration device equipped with a Buchner funnel on the filter bell. Next, the particles remaining on the mesh are observed with a scanning electron microscope (SEM, “S-3500N”, manufactured by Hitachi, accelerating voltage: 25 kV), and the number of coarse particles that are twice or more the average particle diameter is visually determined. I counted. In addition, observation observed the whole visual field at 200-times multiplication factor. The results are shown in Table 1 as “> average diameter × 2”.

  In the case of the amount of coarse particles having an average particle size of 2.5 times or more, the above procedure is used except that a mesh having an opening of 2.25 to 2.5 times the average particle size is used. And performed in the same manner. The results are shown in Table 1 as “> average diameter × 2.5”.

[SiO ₂ content]
In a firing furnace apparatus, 1 g of the polymer particles was fired at 800 ° C. (in the atmosphere), and the ratio of SiO _{2 to} the mass of the polymer particles used was calculated with the generated ash as SiO ₂ .

[Solid content]
The solid content concentration of the polymer particles is determined by drying 0.5 g of the polymer particle dispersion solution at 120 ° C. for 20 minutes (in vacuum), and the ratio of the mass of the remaining solid content to the mass of the polymer particle dispersion is solid. The partial concentration was used.
Solid content concentration (%) = [residual solid content mass / polymer particle dispersion mass] × 100

[Bulk specific gravity]
It measured with the powder tester (made by Hosokawa Micron Corporation).

[Moisture content]
Measurement was performed using a Karl Fischer moisture meter (manufactured by Hiranuma Sangyo Co., Ltd.) using 0.5 g of pulverized particles as a measurement sample.

[Weight average molecular weight]
The weight average molecular weight was measured using gel permeation chromatography (GPC, “HLC-8120GPC”, manufactured by Tosoh Corporation) under the following measurement conditions. The measurement sample was prepared by diluting the sample with tetrahydrofuran (THF) so that the solid content concentration was 0.8%.

Column: TSKgelG5000HXL-TSKgel2000HXL (manufactured by Tosoh Corporation)
Column temperature: 25 ° C
Eluent: THF
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0 ml / min
Detection: R1 Model 504 (manufactured by GL Science Co., Ltd.)
Sample concentration: 0.8%
Standard sample / calibration curve: A calibration curve with 13 samples of standard polystyrene (TSK standard polystyrene, manufactured by Tosoh Corporation), Mw = 500 to 1000000 was used.

Example 1
The polymer particle dispersion obtained in Production Example 1 was classified with a stainless steel wire mesh having an opening of 20 μm (wet classification step). Next, the polymer particle dispersion after wet classification was subjected to solid-liquid separation by natural precipitation. The obtained cake was washed with ion-exchanged water and methanol and then vacuum-dried at 100 ° C. for 5 hours to obtain a dried product in which particles were aggregated. The dried product was pulverized to obtain pulverized particles (recovery rate 99 mass%).

The pulverized particles obtained at this time had a bulk specific gravity of 0.7 g / cm ³ , a particle diameter of 10.1 μm, and a water content of 0.5% by mass or less.

  The obtained pulverized particles are put into a high-precision airflow classifier (“DFX5”, manufactured by Nippon Pneumatic Industry Co., Ltd.) to adjust the balance between centrifugal force and drag force applied to the pulverized particles by high-speed swirling airflow and suction blower. Thus, fine particles were obtained at a recovery rate of 85 mass% with respect to the supplied pulverized particles (dry classification step). At this time, the recovery rate of fine particles from the polymer particle dispersion was 84% by mass.

Example 2
By the same steps as in Example 1, pulverized particles were prepared from the polymer particle dispersion obtained in Production Example 2 (recovery rate 99 mass%). The pulverized particles obtained at this time had a bulk specific gravity of 0.7 g / cm ³ , a particle diameter of 10.1 μm, and a water content of 0.5% by mass or less.

  Next, the obtained pulverized particles are put into a rotary rotor type classifier (“Turboplex 100ATP”, manufactured by Hosokawa Micron Corporation), and the centrifugal force applied to the pulverized particles by the rotation speed of the classification rotor and the supply of air from the intake port. The fine particles were obtained with a recovery rate of 85% by mass with respect to the supplied pulverized particles (dry classification step). At this time, the recovery rate of fine particles from the polymer particle dispersion was 84% by mass.

Example 3
In the same manner as in Example 1, pulverized particles were prepared from the polymer particle dispersion obtained in Production Example 3 (bulk specific gravity 0.7 g / cm ³ , particle diameter 10.1 μm, water content 0.5% by mass or less). , Recovery rate 99 mass%).

  The pulverized particles are put into a rotating rotor type airflow classifier ("Turbo Classifier TC-15", manufactured by Nissin Engineering Co., Ltd.), and the centrifugal speed given to the pulverized particles by the rotation speed of the classifying rotor and the supply of air from the air inlet. Classification was performed by adjusting the balance between force and efficacy, and fine particles were obtained at a recovery rate of 85% by mass with respect to the supplied pulverized particles (dry classification step). At this time, the recovery rate of fine particles from the polymer particle dispersion was 84% by mass.

Example 4
In the same manner as in Example 1, pulverized particles were prepared from the polymer particle dispersion obtained in Production Example 3 (bulk specific gravity 0.7 g / cm ³ , particle diameter 10.1 μm, water content 0.5% by mass or less). 99% recovery).

  The pulverized particles are put into a Coanda type air classifier ("Elbow Jet EJ-15", manufactured by Nippon Steel Mining Co., Ltd., feed air: 5 kgf, using a slim edge), and the inertial force applied to the fine particles and the suction blower Classification was performed by adjusting the balance of efficacy, and fine particles were obtained at a recovery rate of 85 mass% with respect to the supplied ground particles. At this time, the recovery rate of fine particles from the polymer particle dispersion was 84% by mass.

Example 5
The pulverized particles were prepared from the polymer particle dispersion solution obtained in Production Example 4 by the same steps as in Example 1 (bulk specific gravity 0.7 g / cm ³ , particle diameter 3.7 μm, water content 0.5% by mass). Hereinafter, the recovery rate is 99% by mass).

  Subsequently, the obtained pulverized particles are put into a high-precision airflow classifier (“DFX5”, manufactured by Nippon Pneumatic Industry Co., Ltd.), and a balance between centrifugal force and drag force applied to the pulverized particles by a high-speed swirling airflow and a suction blower. And fine particles were obtained with a recovery rate of 88% by mass with respect to the supplied pulverized particles (dry classification step). At this time, the recovery rate of fine particles from the polymer particle dispersion was 87% by mass.

Example 6
By the same steps as in Example 1, pulverized particles were prepared from the polymer particle dispersion solution obtained in Production Example 5 (bulk specific gravity 0.7 g / cm ³ , particle diameter 25.2 μm, water content 0.5% by mass). Hereinafter, the recovery rate is 99% by mass).

  Next, the obtained pulverized particles are put into a rotating rotor type classifier (“Turboplex 100ATP”, manufactured by Hosokawa Micron Corporation), and the centrifugal force applied to the pulverized particles by the rotation speed of the classifying rotor and the supply of air from the intake port. The fine particles were obtained with a recovery rate of 85% by mass with respect to the supplied pulverized particles (dry classification step). At this time, the recovery rate of fine particles from the polymer particle dispersion was 84% by mass.

Example 7
By the same steps as in Example 1, pulverized particles were prepared from the polymer particle dispersion obtained in Production Example 6 (bulk specific gravity 0.7 g / cm ³ , particle diameter 4.2 μm, water content 0.5% by mass). Hereinafter, the recovery rate is 99% by mass).

  The pulverized particles are put into a rotating rotor type airflow classifier ("Turbo Classifier TC-15", manufactured by Nissin Engineering Co., Ltd.), and the centrifugal speed given to the pulverized particles by the rotation speed of the classifying rotor and the supply of air from the air inlet. Classification was performed by adjusting the balance between force and efficacy, and fine particles were obtained at a recovery rate of 86% by mass with respect to the supplied pulverized particles (dry classification step). At this time, the recovery rate of fine particles from the polymer particle dispersion was 85% by mass.

Example 8
By the same steps as in Example 1, pulverized particles were prepared from the polymer particle dispersion obtained in Production Example 7 (bulk specific gravity 0.7 g / cm ³ , particle diameter 12.5 μm, water content 0.5% by mass). Hereinafter, the recovery rate is 99% by mass).

  The pulverized particles are put into a Coanda type air classifier ("Elbow Jet EJ-15", manufactured by Nippon Steel Mining Co., Ltd., feed air: 5 kgf, using a slim edge), and the inertial force applied to the fine particles and the suction blower Classification was performed by adjusting the balance of efficacy, and fine particles were obtained at a recovery rate of 85 mass% with respect to the supplied ground particles. At this time, the recovery rate of fine particles from the polymer particle dispersion was 84% by mass.

Comparative Example 1
The polymer particle dispersion obtained in Production Example 1 was classified with a stainless steel wire mesh having an opening of 20 μm (wet classification step). Subsequently, the polymer particle dispersion after wet classification was separated into individual liquids by natural sedimentation. The obtained cake was washed with ion-exchanged water and methanol and then vacuum-dried at 100 ° C. for 5 hours to obtain a dried product in which particles were aggregated. The dried product was pulverized to obtain pulverized particles.

Comparative Example 2
The polymer particle dispersion obtained in Production Example 2 was classified with a stainless steel wire mesh having an opening of 20 μm, and further passed through a cartridge filter (trade name “Ulple Pleat Profile PUY1UY500”, manufactured by Nippon Pole Co., Ltd.). Processed (wet classification process). Next, the polymer particles were separated, washed and dried in the same manner as in Comparative Example 1, and the obtained dried product was pulverized to obtain pulverized particles.

Comparative Example 3
The polymer particle dispersion obtained in Production Example 5 was classified with a stainless steel wire mesh having an opening of 40 μm (wet classification step). Next, polymer particles were separated, washed and dried in the same procedure as in Comparative Example 1, and the resulting dried product was pulverized to obtain pulverized particles.

  Table 2 shows the contents of the classification treatment in Examples 1 to 8 and Comparative Examples 1 to 3, and the evaluation results on the obtained fine particles and powder particles. Each evaluation method is as follows.

[Measurement of average particle size and amount of coarse particles]
A fine particle size distribution measuring device (product name “Multisizer II”, manufactured by Beckman Coulter, Inc.) was prepared by dispersing 0.5 g of the fine particles obtained in the above Examples and Comparative Examples in 100 g of methanol. ) Was used to measure the particle size, and the average particle size was calculated on a volume basis.

  The amount of coarse particles 1 (coarse particles having a particle size of twice or more the average particle size) was measured as follows. A fine particle dispersion solution (viscosity: 3 mPa · s, solid content concentration: 0.5% by mass) prepared in the same manner as the above average particle size measurement is a mesh having openings of 1.75 to 2 times the average particle size ( Using nickel suction, Tokyo Process Service Co., Ltd.) and a suction filtration device equipped with a Buchner funnel on the filter bell, filtration was performed under reduced pressure.

  Next, using a scanning electron microscope (SEM, “S-3500N”, manufactured by Hitachi, Ltd., acceleration voltage: 25 kV), the particles remaining on the mesh were observed at 200 × and the average particle diameter was visually observed. The number of coarse particles more than twice (number / 0.5 g) was counted.

  In addition, in the case of the amount of coarse particles having an average particle size of 2.5 times or more (coarse particles 2), a mesh having an opening of 2.25 to 2.5 times the average particle size was used. Was performed in the same manner as described above.

[Measurement of the amount of fine particles]
A fine particle dispersion was prepared by dispersing 0.5 g of fine particles obtained in Examples and Comparative Examples in 100 g of ion-exchanged water, and a precision particle size distribution measuring device (product name “Multisizer II”, manufactured by Beckman Coulter, Inc.) Were used to measure the particle size and average particle size (volume basis). Based on the measurement results, the volume% of fine particles having a particle diameter equal to or smaller than ½ of the numerical value obtained by rounding off one decimal place of the average particle diameter was calculated, and the obtained value was defined as the amount of fine particles.

  In Table 2, “Rotating rotor type air classifier 1” used “Turboplex 100ATP” manufactured by Hosokawa Micron Co., Ltd., and “Rotating rotor type air classifier 2” used by “Nisshin Engineering Co., Ltd.” “Turbo Classifier TC”. -15 ”was used. “Coarse particles 1” is the number of particles (particles / 0.5 g) having a particle size 2 times or more of the average particle size, and “coarse particles 2” is particles 2.5 times or more the average particle size. This means the number of particles having a diameter (pieces / 0.5 g), and the “product recovery rate” was recovered through the classification process with respect to the total mass of particles supplied to the classification process in Examples and Comparative Examples. It means the ratio of the total mass of fine particles.

Production Example 8 (Amino resin crosslinked particles)
A reaction kettle provided with a cooling line, a thermometer, and a dripping port was charged with 75 parts of melamine, 75 parts of benzoguanamine, 290 parts of formalin with a concentration of 37%, and 1.16 parts of a sodium carbonate aqueous solution with a concentration of 10%, and an amino resin precursor A body-forming mixture was prepared. The mixture was heated to 85 ° C. with stirring and then kept at the temperature for 1.5 hours to obtain an initial condensate. Separately, a surfactant solution prepared by dissolving 7.5 parts of a nonionic surfactant, Emulgen (registered trademark) 430 (Kao Corporation, polyoxyethylene oleyl ether) in 2455 parts of ion-exchanged water is maintained at 50 ° C. Under stirring, the initial condensate was added thereto to obtain an emulsion of amino resin precursor. To this emulsion, 90 parts of a 5% aqueous solution of dodecylbenzenesulfonic acid was added and condensed and cured at a temperature of 70 to 90 ° C. to obtain a suspension containing amino resin crosslinked particles.

Production Examples 9 and 10 (amino resin crosslinked particles)
A suspension containing amino resin crosslinked particles was prepared in the same manner as in Production Example 8 except that the amounts of amino compound and formalin used were changed to the amounts shown in Table 3.

Production Example 11 (polystyrene particles)
50 parts of styrene, 50 parts of ethylene glycol dimethacrylate, 5 parts of azo polymerization initiator (V-65, manufactured by Wako Pure Chemical Industries), 0.5 part of t-butylhydroquinone, 0.5 part of sodium lauryl sulfate and ion exchange 100 parts of water was mixed, stirred and emulsified to obtain an aqueous dispersion of a polymerizable monomer.

  In a reaction kettle equipped with a cooling line, a thermometer, and a dripping port, 40 parts of monodisperse polystyrene latex (solid content concentration 5%) having a particle diameter of 1 μm is added and dispersed in 200 parts of ion-exchanged water. The body was heated to 65 ° C., and 200 parts of a 2% aqueous solution of polyvinyl alcohol and 200% of a 2% aqueous solution of polyvinyl alcohol were continuously added dropwise over 5 hours. After completion of the dropwise addition, the temperature was raised to 85 ° C. and kept at this temperature for 3 hours to obtain a suspension containing polystyrene particles.

Production Example 12 (polystyrene particles)
As shown in Table 4, the combination of radically polymerizable monomers was changed, and the addition amount of monodisperse polystyrene latex (particle size: 0.6 μm (Production Example 12), 0.7 μm (Production Example 13)) was adjusted as appropriate. Except for the above, a polystyrene latex fine particle dispersion solution was prepared in the same manner as in Production Example 11.

Example 9
The polymer dispersion obtained in Production Example 3 is filtered with a configuration in which a plurality of cartridge filters are combined (prefilter 1: HC-75, prefilter 2: HC-25, final filter: SLP300, all manufactured by Loki Techno). Treatment was performed (wet classification step).

  Next, the dispersion is subjected to solid-liquid separation by natural sedimentation, and the resulting cake is washed with ion-exchanged water and methanol, and then vacuum dried at 100 ° C. for 5 hours to obtain a dried product in which particles are aggregated. It was. The dried product was pulverized to obtain particles.

The pulverized fine particles obtained at this time had a bulk specific gravity of 0.7 g / cm ³ , a particle size of 6.9 μm, a water content of 0.5% by mass or less, and a recovery rate of 97% by mass.

  Apply this to a Coanda airflow classifier (Elbow Jet EJ-15, manufactured by Nippon Steel & Mining Co., Ltd., feed air: 5 kgf, using a slim edge) to adjust the balance between the inertial force applied to the fine particles and the drag by the suction blower And fine particles classified at a recovery rate of 89% by mass with respect to the supplied pulverized particles were obtained (dry classification step).

Example 10
By the same steps as in Example 9, pulverized particles were prepared from the polymer dispersion obtained in Production Example 8 (bulk specific gravity 0.6 g / cm ³ , particle diameter 8.5 μm, water content 1.0% by mass). Hereinafter, the recovery rate is 96% by mass).

  By introducing the pulverized particles into a high-precision airflow classifier (DFX5 type, manufactured by Nippon Pneumatic Industry Co., Ltd.), adjusting the balance between the centrifugal force applied to the pulverized particles by the high-speed swirling airflow and the drag by the suction blower Classification was performed to obtain fine particles classified at a recovery rate of 85% by mass with respect to the supplied pulverized particles (dry classification step).

Example 11
By the same steps as in Example 9, pulverized fine particles were prepared from the polymer dispersion solution obtained in Production Example 11 (bulk specific gravity 0.7 g / cm ³ , particle diameter 4.0 μm, water content 0.5 mass%). Hereinafter, the recovery rate is 97% by mass).

  The pulverized particles are put into a rotary rotor type airflow classifier (Turbo Classifier TC-15, manufactured by Nissin Engineering Co., Ltd.), and the centrifugal force and effectiveness given to the pulverized particles by the rotation speed of the classifying rotor and the supply of air from the intake port. By adjusting the balance, fine particles classified at a recovery rate of 85% by mass with respect to the supplied pulverized particles were obtained (dry classification step).

Example 12
In the same manner as in Example 1, pulverized fine particles were prepared from the polymer particle dispersion obtained in Production Example 10 (bulk specific gravity 0.6 g / cm ³ , particle diameter 13.1 μm, water content 1.0 mass). % Or less, recovery rate 99 mass%).

  The obtained pulverized fine particles are put into a Coanda airflow classifier (Elbow Jet EJ-15, manufactured by Nippon Steel Mining Co., Ltd., feed air: 5 kgf, using a slim edge), and the rotational speed of the classification rotor and the air from the intake port Classification was performed by adjusting the balance between the centrifugal force applied to the pulverized particles and the efficacy by supply, and fine particles classified at a recovery rate of 85% by mass with respect to the supplied pulverized particles were obtained (dry classification step).

Example 13
In the same manner as in Example 1, pulverized fine particles were prepared from the polymer particle dispersion obtained in Production Example 9 (bulk specific gravity 0.6 g / cm ³ , particle diameter 2.0 μm, water content 1.0 mass). % Or less, recovery rate 99 mass%).

  The obtained pulverized fine particles are put into a high-precision airflow classifier (DFX5 type, manufactured by Nippon Pneumatic Industry Co., Ltd.), and the balance between the centrifugal force applied to the pulverized particles by the high-speed swirling airflow and the drag force by the suction blower is adjusted. Thus, fine particles classified at a recovery rate of 80% by mass with respect to the supplied pulverized particles were obtained.

Example 14
In the same manner as in Example 1, pulverized fine particles were prepared from the polymer particle dispersion obtained in Production Example 12 (bulk specific gravity 0.7 g / cm ³ , particle diameter 6.5 μm, water content 0.5 mass). % Or less, recovery rate 99 mass%).

  The obtained pulverized fine particles are put into a Coanda airflow classifier (Elbow Jet EJ-15, manufactured by Nippon Steel Mining Co., Ltd., feed air: 5 kgf, using a slim edge), and the rotational speed of the classification rotor and the air from the intake port Classification was performed by adjusting the balance between the centrifugal force applied to the pulverized particles and the effect of the supply, and fine particles classified at a recovery rate of 87 mass% with respect to the supplied pulverized particles were obtained.

Example 15
In the same manner as in Example 1, pulverized fine particles were prepared from the polymer particle dispersion obtained in Production Example 13 (bulk specific gravity 0.7 g / cm ³ , particle diameter 9.3 μm, water content 0.5 mass). % Or less, recovery rate 99 mass%).

  The obtained pulverized fine particles are put into a rotary rotor type airflow classifier (Turbo Classifier TC-15, manufactured by Nissin Engineering Co., Ltd.), and the rotational speed of the classification rotor and the centrifugal force applied to the pulverized particles by the supply of air from the intake port Classification was performed by adjusting the balance of efficacy, and fine particles classified at a recovery rate of 83 mass% with respect to the supplied ground particles were obtained.

Comparative Example 4
In the same manner as in Example 1, pulverized fine particles were prepared from the polymer particle dispersion obtained in Production Example 12 (bulk specific gravity 0.7 g / cm ³ , particle diameter 6.5 μm, water content 0.5 mass). % Or less, recovery rate 99 mass%).

  The obtained pulverized fine particles are put into a Coanda airflow classifier (Elbow Jet EJ-15, manufactured by Nippon Steel Mining Co., Ltd., feed air: 5 kgf, using a slim edge), and the rotational speed of the classification rotor and the air from the intake port Classification was performed by adjusting the balance between the centrifugal force applied to the pulverized particles by supply and the efficacy, and fine particles classified at a recovery rate of 75 mass% with respect to the supplied pulverized particles were obtained.

Comparative Example 5
Ground fine particles were prepared from the polymer particle dispersion obtained in Production Example 3 in the same manner as in Example 1 except that wet classification was not performed (bulk specific gravity 0.7 g / cm ³ , particle size 6. 9 μm, water content 0.5 mass% or less).

  The obtained pulverized fine particles are put into a rotary rotor type airflow classifier (Turbo Classifier TC-15, manufactured by Nissin Engineering Co., Ltd.), and the rotational speed of the classification rotor and the centrifugal force applied to the pulverized particles by the supply of air from the intake port Classification was performed by adjusting the balance of efficacy, and fine particles classified at a recovery rate of 90% by mass with respect to the supplied pulverized particles were obtained (first dry classification). Thereafter, the same dry classification process was repeated to obtain fine particles classified at a recovery rate of 90% by mass with respect to the supplied pulverized particles (second dry classification).

  Table 5 shows the contents of the classification treatment in Examples 9 to 13 and Comparative Example 4, and the evaluation results on the obtained fine particles and powder particles. Each evaluation method is as described above.

  In addition, the comparative example 5 is an example which repeated the dry classification as a classification process twice. Coarse particles were not sufficiently removed only by repeated dry classification. Moreover, the tendency for a product recovery rate to fall by repeating dry classification is seen, and it turns out that an industrial product yield is difficult to be obtained only by dry classification.

Example 16 Production of Antiglare Film 3 parts by mass of each resin particle obtained in Examples 1, 9, 10 and Comparative Example 4 and 20 parts by mass of toluene were sufficiently stirred and mixed. In this mixed solution, 40 parts by mass of an acrylic ionizing radiation curable resin, 2 parts by mass of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals, "Irgacure (registered trademark) 907"), 23 parts by mass of methyl ethyl ketone, 2 parts by mass of ethylene glycol monobutyl ether Part and a leveling agent (BYK320, manufactured by BYK Chemie) were added and sufficiently stirred to prepare a coating solution.

The coating solution was applied to one side of a 80 μm thick triacetylcellulose film (Fuji Photo Film, “Fujitac (registered trademark)”) with a bar coater. The obtained coating film was dried with a dryer at 80 ° C., and then an antiglare film was produced by irradiating 300 mJ / cm ² of ultraviolet rays using a high pressure mercury lamp to cure the resin component.

A black film was bonded to the back surface of each antiglare film, a fluorescent light of 10,000 cd / m ² was projected from a position 2 m away from the film, and the degree of blur of the reflected image was evaluated according to the following criteria. The results are shown in Table 6.
○: The outline of the fluorescent lamp cannot be identified.
X: The outline of the fluorescent lamp can be clearly distinguished.

  Moreover, about each anti-glare film, the transmission sharpness (image sharpness) was measured according to JIS K7105 using a mapping measuring device (ICB-IDD made by Suga Test Instruments Co., Ltd.) and an optical comb having a width of 0.5 mm. .

Furthermore, each anti-glare film was bonded to the surface of a liquid crystal monitor (15 inch XGA, TFT-TN system, front luminance: 350 cd / m ² , front contrast: 300 to 1, surface AG: none) connected to a personal computer, Character blur was evaluated according to the following criteria. The results are shown in Table 6.
○: The outline of the character is not blurred at all.
X: The outline of a character is blurred and a strong sense of incongruity is felt.

  As can be seen from Table 6, the antiglare films obtained using the particles of Examples 1, 9 and 10 both have excellent antiglare properties and visibility (no blurring of characters). . On the other hand, although the antiglare film produced using the particles of Comparative Example 4 having a large amount of coarse particles exceeding twice the average particle diameter has antiglare properties, the coarse particles contained in the antiglare film are like lenses. It is thought that the film surface was damaged due to the action or the coarse particles, and as a result, it was difficult to visually recognize the characters.

  The fine particles of the present invention are those in which the content of coarse particles and fine particles that deviate from the preferred range of particle size is reduced to a low level. Therefore, various optical films or sheets (antiglare sheet, light diffusion film, etc.) produced using such fine particles are less likely to suffer from defects derived from coarse particles and a decrease in transparency derived from fine particles. It is thought that Moreover, since unevenness | corrugation is uniformly formed in a surface, it is thought that the outstanding optical characteristic (for example, anti-glare property and light diffusivity) is exhibited.

Claims (8)

  Fine particles characterized in that coarse particles having a particle size of at least twice the average particle size are 1000 particles / 0.5 g or less.   The fine particle according to claim 1, wherein the fine particle is an organic-inorganic composite including an organic polymer skeleton and a polysiloxane skeleton. A method for producing fine particles according to claim 1 or 2,
A step of wet-classifying a fine particle dispersion having a solid content concentration of 0.5 to 50% by mass and a B-type viscosity of 0.5 to 20 mPa · s,
A step of drying and pulverizing the fine particles after the wet classification into powder fine particles having a moisture content of 0.05 to 2% by mass;
A method for producing fine particles, comprising a step of dry-classifying the powder fine particles.   A resin composition comprising the fine particles according to claim 1.   A coating composition comprising the resin composition according to claim 4.   An optical film obtained by applying the coating composition according to claim 5 on a substrate.   The optical film according to claim 6, which is used as a light diffusion film. The optical film according to claim 6, which is used as an antiglare film.