Powder granulation product and method for producing powder granulation product

Abstract

To provide a powder granulation product containing spherical polymer fine particles, which is excellent in optical properties, physical properties and productivity. [Solution] The powder granule according to an embodiment of the present invention comprises spherical polymer microparticles (A), transparent polymer powder (B), and a binder (C), wherein the content of the spherical polymer microparticles (A) is 10 to 97 parts by mass relative to 100 parts by mass of the powder granule, the content of the transparent polymer powder (B) is 1 to 88 parts by mass relative to 100 parts by mass of the powder granule, and the content of the binder (C) is 2 to 30 parts by mass (dry mass) relative to 100 parts by mass of the powder granule, and the binder (C) comprises an aqueous polymer, and the aqueous polymer has hydrophilic groups and hydrophobic groups.

Description

[Technical Field]

[0001] The present invention relates to a powder granulation product and a method for producing the powder granulation product. [Background technology]

[0002] In the production of polymers (e.g., thermoplastic polymers), powdered polymers can be obtained, in part, due to the method used, and one form of such polymers is known to be spherical polymer microparticles. Powdered polymers are generally blended with thermoplastic resins by melt-kneading, but to improve their handling properties, uniformity of concentration, and productivity, it is desirable to prepare them into masterbatches of appropriate concentrations. From another perspective, masterbatching is also desirable to improve dusty working environments and prevent dust explosions. Masterbatches with controlled composition ratios can generally be obtained by quantitatively feeding the polymers into a melt-kneading device such as an extruder via a screw-type gravimetric feeder.

[0003] However, when spherical polymer microparticles are used, the rolling resistance of the microparticles is extremely small, making it difficult to control the quantitative flow rate using a gravimetric feeder screw, and it is difficult to continuously supply the microparticles stably with high precision, which may cause the desired concentration uniformity to be unobtainable. Furthermore, the low bulk density of the spherical polymer microparticles prevents an increase in the flow rate, which may result in problems such as limitations on the ability to increase the concentration and the production rate of the masterbatch.

[0004] The spherical polymer fine particles are sometimes blended into a transparent resin and used as a light diffusing agent. A light diffusing resin composition containing the spherical polymer fine particles as a light diffusing agent is required to have both light diffusing properties and light transmittance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2023-011323 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a powder granulation product containing spherical polymer microparticles, which has excellent optical properties, compositional uniformity, granulation product stability, dispersibility in thermoplastic resins, color tone retention, and productivity. [Means for solving the problem]

[0007] 1. A powder granule according to an embodiment of the present invention comprises spherical polymer microparticles (A), transparent polymer powder (B), and a binder (C), wherein the content of the spherical polymer microparticles (A) is 10 parts by mass to 97 parts by mass relative to 100 parts by mass of the powder granule, the content of the transparent polymer powder (B) is 1 part by mass to 88 parts by mass relative to 100 parts by mass of the powder granule, and the content of the binder (C) is 2 parts by mass to 30 parts by mass (dry mass) relative to 100 parts by mass of the powder granule, and the binder (C) comprises an aqueous polymer, and the aqueous polymer has hydrophilic groups and hydrophobic groups. 2. In the powder granulation product described in 1 above, the material constituting the spherical polymer microparticles (A) may be one or more selected from the group consisting of crosslinked acrylic resins, crosslinked styrene resins, crosslinked acrylic-styrene resins, crosslinked silicone resins, crosslinked silicone-acrylic resins, melamine resins, and benzoguanamine resins. 3. In the powder granulation product according to 1 or 2 above, the ratio (b / a) of the minor axis b of the spherical polymer microparticles (A) to the major axis a of the spherical polymer microparticles (A) may be 0.9 or more. 4. In the powder granulation product according to any one of the above 1 to 3, the median diameter (D50) of the spherical polymer fine particles (A) may be 0.1 μm to 300 μm. 5. In the powder granulation product according to any one of the above items 1 to 4, the spherical polymer fine particles (A) may have a bulk density of 0.05 kg / L to 1.0 kg / L. 6. In the powder granulation product according to any one of the above items 1 to 5, the refractive index of the spherical polymer fine particles (A) may be 1.40 to 1.70. 7. In the powder granule described in any one of 1 to 6 above, the material constituting the transparent polymer powder (B) may be one or more selected from the group consisting of styrene-based resins, acrylic-based resins, styrene-methacrylate-based resins, polycarbonate-based resins, polyester-based resins, polyurethane-based resins, petroleum resins, terpene-based resins, and alicyclic polyolefin-based resins. 8. In the powder granulated product according to any one of the above 1 to 7, the transparent polymer powder (B) may have a median diameter (D50) of 1 μm to 3000 μm. 9. In the powder granulated product according to any one of the above 1 to 8, the refractive index of the transparent polymer powder (B) may be 1.45 to 1.65. 10. In the powder granulated product according to any one of the above 1 to 9, the transparent polymer powder (B) may have a bulk density of 0.10 kg / L to 0.70 kg / L. 11. In the powder granulated product according to any one of 1 to 10 above, the median diameter (D50) of the aqueous polymer may be 0.5 μm or less. 12. In the powder granulated product according to any one of 1 to 11 above, the aqueous polymer may be one or more types selected from the group consisting of acrylic resins, polyester resins, and polyurethane resins. 13. The powder granulated product according to any one of 1 to 12 above may have a breaking stress of 0.3 kg or more as measured by a Kiya hardness tester. 14. The powder granulated product according to any one of 1 to 13 above may have a bulk density of 0.3 kg / L to 1.0 kg / L. 15. The powder granulated product according to any one of 1 to 14 above may have a median diameter (D50) of 1 mm to 10 mm. 16. The powder granulated product according to any one of 1 to 5 above may have a substantially cylindrical or substantially prismatic shape. 17. A method for producing the powder granules according to an embodiment of the present invention includes a mixing step of mixing spherical polymer fine particles (A), transparent polymer powder (B), and a binder (C) to obtain a powder mixture; The method includes a granulation step of compressing and granulating the powder mixture to obtain a powder granulation precursor; and a heating step of heating the powder granulation precursor. 18. In the method for producing a powder granulated product described in 17 above, in the granulation step, the compression granulation method may be a disk pelletizer method. 19. In the method for producing a powder granulated product described in 17 or 18 above, the binder (C) may contain an aqueous polymer, and the mixing step may include adding an aqueous solution containing the aqueous polymer or an aqueous dispersion containing the aqueous polymer. 20. The powder granules according to the embodiment of the present invention may be used as a raw material for a compound containing a thermoplastic resin, or as a molding material. 21. The powder granulated material described in 20 above may be used as a raw material for a thermoplastic resin compound containing one or more thermoplastic resins selected from the group consisting of styrene-based resins, acrylic-based resins, styrene-methacrylate-based resins, polycarbonate-based resins, and alicyclic polyolefin-based resins. 22. In the use of the powder granules according to 20 or 21 above, the ratio (nP / nB) of the refractive index nB of the transparent polymer powder (B) to the refractive index nP of the thermoplastic resin may be 0.8 to 1.2. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a powder granulation product containing spherical polymer microparticles, which has excellent optical properties, compositional uniformity, granulation stability, dispersibility in thermoplastic resins, color tone retention, and productivity. [Brief explanation of the drawings]

[0009] [Figure 1]1 is a photograph showing the appearance of the granulated product of Example 1. [Figure 2] 1 is an image of a cross section of the powder granulated product obtained in Example 1 observed with a scanning electron microscope (SEM). DETAILED DESCRIPTION OF THE INVENTION

[0010] A. Overview of powder granulation The powder granules according to an embodiment of the present invention comprise spherical polymer particles (A), transparent polymer powder (B), and a binder (C). The spherical polymer particles (A), transparent polymer powder (B), and binder (C) can be distinguished by their shapes (typically, by cross-sectional observation). The spherical polymer particles (A) have a median diameter (D50) of 0.1 μm or more and are spherical. The transparent polymer powder (B) refers to a polymer that has a median diameter (D50) of 0.1 μm or more, is non-spherical, and is transparent. In this specification, "spherical" refers to a shape in which the ratio (b / a) of the minor axis b to the major axis a is 0.9 or more, and "non-spherical" is a general term for shapes other than "spherical." "Transparent" refers to a state in which light is efficiently transmitted without reflection, and a haze (%) value of a 1 mm thick sample according to JIS K7136 for plastics is less than 4%. The binder (C) refers to a component that is not in a granular form in the powder granules. In one embodiment, the binder (C) is present between components (A) and (A), between components (B) and (B), or between components (A) and (B), and is present to bind the components together and stabilize the shape of the powder granules.

[0011] In one embodiment, the content of the spherical polymer fine particles (A) is 10 parts by mass to 97 parts by mass per 100 parts by mass of the powder granules. The content of the transparent polymer powder (B) is 1 part by mass to 88 parts by mass per 100 parts by mass of the powder granules. The content of the binder (C) is 2 parts by mass to 30 parts by mass (dry mass) per 100 parts by mass of the powder granules. In one embodiment, the total content of the spherical polymer fine particles (A), the transparent polymer powder (B), and the binder (C) is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, even more preferably 90 parts by mass or more, and even more preferably 95 parts by mass or more per 100 parts by mass of the powder granules. In one embodiment, the total content of the spherical polymer microparticles (A), the transparent polymer powder (B), and the binder (C) is 100 parts by mass relative to 100 parts by mass of the powder granules (i.e., the powder granules are composed of three components, component (A), component (B), and component (C)).

[0012] In one embodiment, the powder granules can be obtained by processing a mixture containing the spherical polymer fine particles (A), the transparent polymer powder (B), and the binder (C) (for example, the binder can be formulated as an aqueous solution or aqueous dispersion) by any appropriate method. In one embodiment, the powder granules are produced by a semi-wet granulation method.

[0013] In one embodiment, the powder granulation product is composed of spherical polymer particles (A) and transparent polymer powder (B) bound together by the action of a binder (C). By forming the powder granulation product from these components, a powder granulation product can be obtained as a compressed granule. The powder granulation product has excellent quality stability (shape stability, uniform hardness, and low fine powder contamination). Furthermore, the powder granulation product has excellent optical properties, composition uniformity, granulation stability, dispersibility in thermoplastic resins, color retention, and productivity. Furthermore, the powder granulation product can be produced without melting the spherical polymer particles (A), which is advantageous in that there is a wide range of choices for the type of spherical polymer particles (A) used as a raw material. Furthermore, because the granulation product is obtained without melting the spherical polymer particles (A), thermal deterioration (e.g., yellowing) of the spherical polymer particles (A) can be prevented.

[0014] The powder granules contain transparent polymer powder (B), which allows the range of the content of the spherical polymer microparticles (A) in the powder granules to be suitably adjusted. In one embodiment, the concentration of the spherical polymer microparticles (A) in the powder granules can be freely controlled to an appropriate level. Therefore, for example, when used as a light diffusing agent masterbatch, the powder granules can be provided as a light diffusing agent masterbatch, which allows for easy control of the light diffusing agent concentration in the final light diffusing resin composition, resulting in an easy-to-handle powder granule. Furthermore, by suitably selecting the refractive index of the transparent polymer powder (B), the optical properties (balance between light diffusivity and transmittance) of the resin composition obtained by using the powder granules as a light diffusing agent masterbatch can be improved.

[0015] The binder (C) includes an aqueous polymer. The aqueous polymer preferably has a hydrophilic group and a hydrophobic group. According to an embodiment of the present invention, by using a specific binder (C), the amount of binder (C) can be reduced, resulting in a powder granule with excellent dispersibility and little coloration. Furthermore, by using the binder (C), powder granules can be produced with excellent efficiency, and powder granules with excellent handleability, such as stable quality (shape stability and uniform composition), low fineness, and sufficient granule breaking strength, can be obtained.

[0016] The powder granulated material can be added to a resin composition in various plasticizing melt processing processes, including melt compounding (melt kneading) of the resin composition.

[0017] Adding the powder granules to plasticizing melt processing (typically melt kneading) of a resin composition can improve productivity in the melt kneading process. Specifically, because the powder granules have excellent stability when fed into equipment such as extruders, their use can dramatically improve productivity (compound processing rate per hour) while efficiently dispersing the spherical polymer microparticle powder (A) into the resin composition. Furthermore, they can significantly reduce work environment pollution caused by dust, greatly reduce the risk of dust explosions, and significantly shorten the time required for cleaning equipment changeovers. The powder granules can also be directly fed into various resin molding machines, such as injection molding and extrusion molding, to obtain molded products. In this case, the "melt kneading pelletization" step can be omitted, significantly reducing the amount of carbon dioxide generated during the entire production process compared to conventional methods (resin product processing methods that include a melt kneading pelletizing step).

[0018] The powder granules can be used in fields where spherical polymer microparticles are used, such as cosmetics, paints, resin molded products, and building materials, for applications aimed at improving light diffusion, hiding properties, coatability, and texture. In one embodiment, a mixture (resin composition) of the powder granules and any appropriate thermoplastic resin (hereinafter referred to as the thermoplastic resin to which the powder granules are applied) is provided. The mixture can be used in the above applications. In one embodiment, the powder granules can be preferably used as a masterbatch when producing a resin composition having light diffusion properties.

[0019] The powder granulated product may have any appropriate shape. Typically, the powder granulated product is cylindrical (pellet-shaped), and preferably has a substantially cylindrical or substantially prismatic shape.

[0020] When the powder granules are cylindrical (preferably substantially cylindrical or substantially prismatic), the diameter of the powder granules is, for example, 1 mm to 10 mm, preferably 2 mm to 8 mm, more preferably 2 mm to 6 mm, even more preferably 2.5 mm to 5 mm, and particularly preferably 2.8 mm to 3.5 mm. The length (height) of the powder granules is, for example, 1 mm to 10 mm, preferably 2 mm to 8 mm, more preferably 2 mm to 7 mm, even more preferably 2.5 mm to 6 mm, and particularly preferably 2.8 mm to 5.5 mm. The median diameter (D50, volumetric basis) of the powder granules is preferably in the range of 1 mm to 10 mm. Such a shape makes it possible to obtain a powder granules that is easy to handle. In particular, when the powder granules are mixed with a thermoplastic resin, separation from the raw thermoplastic resin during production is reduced, improving handleability and composition uniformity. The diameter of the powder granules can be adjusted by the diameter of the die holes in the disc plate during granulation, and the length can be adjusted by the distance between the disc plate and the cutter. This distance can be any appropriate distance depending on the type of powdered thermoplastic polymer, etc. The distance between the disc plate and the cutter is, for example, 1 mm to 30 mm, more preferably 2 mm to 20 mm, and even more preferably 3 mm to 10 mm. In this specification, the median diameter is based on volume.

[0021] The breaking stress of the powder granules measured with a Kiya hardness tester is preferably 0.3 kg or more, more preferably 0.5 kg or more, even more preferably 1.0 kg or more, even more preferably 5.0 kg or more, even more preferably 7.0 kg or more, and particularly preferably 10 kg or more. The upper limit may exceed the measurement limit of the Kiya hardness tester (the measurement limit of the Shiro Sangyo Co., Ltd. product, "WPF1600-B," is 10 kg). Within this range, a powder granule with excellent handleability and melt processability can be obtained. Here, the breaking strength refers to the average breaking stress (breaking load) measured by crushing 20 or more particles (preferably 25 or more particles) of the powder granules using a pressure attachment in a direction perpendicular to the longitudinal direction (extrusion direction) of the powder granules. The diameter of the pressure surface of the pressure attachment of the Kiya hardness tester is, for example, 5 mm.

[0022] The bulk density of the powder granulation product can be any appropriate bulk density depending on the type of powdered thermoplastic polymer. The bulk density of the powder granulation product is preferably 0.3 kg / L to 1.0 kg / L, more preferably 0.5 kg / L to 0.9 kg / L. In one embodiment, the bulk density of the powder granulation product is 0.3 kg / L to 0.8 kg / L. Increasing the bulk density improves the supply speed and supply stability of the powder granulation product to various processing machines. The bulk density is calculated by allowing the powder granulation product to fall naturally into a measure (volume 1 L) until it is filled to the brim, and then measuring the mass of the powder granulation product (unit: kg / L).

[0023] The moisture content of the powder granulation product can be any appropriate moisture content. The moisture content of the powder granulation product is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass or less, particularly preferably 1% by mass or less, and most preferably 0.5% by mass or less. The moisture content of the powder granulation product is measured using an infrared moisture meter.

[0024] A-1. Spherical polymer particles (A) The spherical polymer particles (A) can be used, for example, in cosmetics, paints, optical applications, resins, building materials, etc. Their functions include light diffusion, hiding properties, coatability, and texture.

[0025] As described above, in this specification, "spherical" refers to a shape in which the ratio of the minor axis b to the major axis a (b / a) of the particle is 0.9 or more. The ratio b / a is preferably 0.92 or more, and more preferably 0.95 or more. Within this range, the above functions can be preferably exhibited. The major axis a and the minor axis b are the number averages of 50 or more (preferably 100 or more) particles observed with a scanning electron microscope (SEM).

[0026] As described above, the content of the spherical polymer microparticles (A) is 10 to 97 parts by mass relative to 100 parts by mass of the powder granules. The content of the spherical polymer microparticles (A) is preferably 15 to 95 parts by mass, more preferably 20 to 90 parts by mass, and even more preferably 30 to 80 parts by mass relative to 100 parts by mass of the powder granules. Within these ranges, a good powder granule can be obtained that is excellent in granulation stability, dispersibility in thermoplastic resins, and breaking strength. Furthermore, when blended with a thermoplastic resin, the spherical polymer microparticles (A) can be well dispersed in the resin, and economically advantageous as a high-concentration masterbatch can be obtained.

[0027] The spherical polymer particles (A) may be made of any suitable material. Typically, the spherical polymer particles (A) may be made of an organic polymer. Examples of materials that may be used to make the spherical polymer particles (A) include acrylic resins, styrene resins, acrylic-styrene resins, silicone resins, silicone-acrylic resins, melamine resins, benzoguanamine-based particles, polyamide-based particles, polyurethane-based particles, and biodegradable resin-based particles (polyhydroxyalkanoate (PHA), polylactic acid (PLA), polycaprolactam (PCL), polybutylene succinate (PBS), acetyl cellulose (TAC), etc.). The resins may be crosslinked. The spherical polymer particles (A) may be made of one type of resin or two or more types of resins.

[0028] Preferably, the spherical polymer particles (A) are composed of a crosslinked resin. In one embodiment, the material constituting the spherical polymer particles (A) is one or more selected from the group consisting of crosslinked acrylic resins, crosslinked styrene resins, crosslinked acrylic-styrene resins, crosslinked silicone resins, crosslinked silicone-acrylic resins, melamine resins, and benzoguanamine resins. More preferably, the material is one or more selected from the group consisting of crosslinked acrylic resins, crosslinked styrene resins, crosslinked acrylic-styrene resins, crosslinked silicone resins, and crosslinked silicone-acrylic resins.

[0029] The refractive index of the spherical polymer particles (A) is, for example, 1.40 to 1.70, and preferably 1.42 to 1.70. In one embodiment, the refractive index of the spherical polymer particles (A) can be appropriately selected in consideration of the refractive index of the thermoplastic resin to which the powder granules are applied, for the purpose of obtaining light diffusion function. For example, when the thermoplastic resin to which the powder granules are applied is polycarbonate (refractive index 1.57 to 1.59) or styrene-based resin (refractive index 1.58 to 1.60), the spherical polymer particles (A) can preferably be a crosslinked acrylic resin, a crosslinked acrylic-styrene-based resin, or a crosslinked silicone-based resin or a crosslinked silicone-acrylic resin, each having a refractive index of 1.49 to 1.55. Furthermore, when the transparent thermoplastic resin to which the powder granules are applied is an acrylic resin (refractive index 1.49), a cellulose acetate resin (refractive index 1.46 to 1.50), or the like, the spherical polymer microparticles (A) can preferably be selected from crosslinked silicone resins or crosslinked silicone-acrylic resins having a refractive index of 1.41 to 1.45, and crosslinked acrylic-styrene resins having a refractive index of 1.55 to 1.58.

[0030] The bulk density of the spherical polymer particles (A) is preferably 0.05 kg / L to 1.0 kg / L, more preferably 0.1 kg / L to 0.8 kg / L, and more preferably 0.2 kg / L to 0.6 kg / L. When the bulk density of the spherical polymer particles (A) is within this range, granulation is easy.

[0031] The median diameter (D50) of the spherical polymer microparticles (A) is preferably 0.1 μm to 300 μm, more preferably 0.5 μm to 200 μm, even more preferably 0.8 μm to 100 μm, particularly preferably 1 μm to 50 μm, and most preferably 2 μm to 20 μm. Within these ranges, a powder granulated product with excellent light diffusing properties can be obtained. The median diameter (D50) of the spherical polymer microparticles (A) can be measured for the primary particles of the particles by laser diffraction.

[0032] Commercially available products can be used as the spherical polymer microparticles (A), and examples thereof include "Ganzpearl (trade name)" manufactured by Aica Kogyo Co., Ltd., "Techpolymer (trade name)" manufactured by Sekisui Chemical Co., Ltd., "Eposter (trade name)" and "Soliostar (trade name)" manufactured by Nippon Shokubai Co., Ltd., "Tospearl (trade name)" manufactured by Momentive Performance Materials, Inc., "KMP Series (trade name)" manufactured by Shin-Etsu Polymer Co., Ltd., "Artpearl (trade name)" manufactured by Negami Chemical Industrial Co., Ltd., and "Trepearl (trade name)" manufactured by Toray Industries, Inc.

[0033] A-2. Transparent polymer powder (B) The addition of transparent polymer powder (B) makes it possible to adjust the concentration of spherical polymer microparticles (A). The addition of transparent polymer powder (B) is also advantageous in improving the dispersibility of the spherical polymer microparticles (A) in thermoplastic resins. Furthermore, in the compression granulation process of the powder granulation product, the addition of transparent polymer powder (B) improves the fluidity of the powder raw material and its penetration into the die, thereby increasing the granulation rate and improving processing stability, and also contributing to improving the breaking strength of the powder granulation product.

[0034] The softening temperature of the transparent polymer powder (B) is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 80°C or higher. A softening temperature of 50°C or higher enables stable continuous production of powder granules at a high granulation rate. The "softening temperature" refers to the melting point or glass transition temperature at which the polymer substantially softens in response to external stress, and can be measured by a differential scanning calorimeter (DSC). In one embodiment, the softening temperature corresponds to the melting point when an endothermic or exothermic peak is observed in the DSC measurement, and corresponds to the glass transition temperature when only a baseline discontinuity is observed. When both the "melting point" and the "glass transition temperature" are observed, the "melting point" is taken as the softening temperature.

[0035] As described above, the content of the transparent polymer powder (B) is 1 to 88 parts by mass relative to 100 parts by mass of the powder granules. The content of the transparent polymer powder (B) is preferably 2 to 85 parts by mass, more preferably 3 to 80 parts by mass, even more preferably 5 to 75 parts by mass, and particularly preferably 8 to 70 parts by mass relative to 100 parts by mass of the powder granules. The amount of the transparent polymer powder (B) added can be appropriately selected taking into consideration the dispersibility of the spherical polymer fine particles (A) in the thermoplastic resin when blended therewith and the economical advantage as a masterbatch.

[0036] In one embodiment, the transparent polymer powder (B) is preferably transparent and optically isotropic. The refractive index of the transparent polymer powder (B) can be determined depending on the thermoplastic resin to which the powder granules are applied. The refractive index of the transparent polymer powder (B) is, for example, 1.45 to 1.65, and preferably 1.47 to 1.60.

[0037] The transparent polymer powder (B) is preferably amorphous or nearly amorphous. Here, "amorphous" means that no endothermic peak of crystalline melting is observed in differential scanning calorimetry (DSC) measurement (heating rate: 10°C / min).

[0038] The transparent polymer powder (B) is in powder form. It may be a powdered resin obtained through a manufacturing process, i.e., a powder resulting from the manufacturing process, or a powdered resin obtained by pulverizing a non-powdered resin such as a pelletized resin, a lump of resin, or a resin molded body. The pulverized powdered resin can be obtained by cooling a molded product, pellets, or a sprue or runner generated during injection molding at room temperature or, if necessary, with dry ice or liquid nitrogen, and then using a pulverizer (e.g., Dalton products under the trade names "Nea Mill," "Sylphid Mill," "Atomizer," or "Impact Mill").

[0039] The transparent polymer powder (B) is preferably amorphous and has a structure with a large surface area per unit mass. For example, a powdered resin obtained by pulverization may be preferable. Such a shape allows the binding effect of the binder (C) to be effectively exerted, thereby increasing the breaking strength of the powder granules.

[0040] Examples of materials constituting the transparent polymer powder (B) include styrene-based resins, acrylic-based resins, styrene-methacrylate-based resins, polycarbonate-based resins, polyester-based resins, polyurethane-based resins, petroleum resins, terpene-based resins, and alicyclic polyolefin-based resins. These resins may be used alone or in combination of two or more. These resins are advantageous in that they have good optical compatibility with the thermoplastic resin to which the powder granules are applied when the powder granules are used as a light diffusing agent.

[0041] The transparent polymer powder (B) may have any appropriate particle size as long as the effects of the present invention are obtained. The median diameter (D50) of the transparent polymer powder (B) is preferably 1 μm to 3,000 μm, more preferably 5 μm to 1,000 μm, even more preferably 10 μm to 800 μm, still more preferably 20 μm to 600 μm, still more preferably 50 μm to 400 μm, and particularly preferably 100 μm to 300 μm.

[0042] The bulk density of the transparent polymer powder (B) may be any appropriate value as long as the effects of the present invention are obtained. The bulk density of the transparent polymer powder (B) is preferably 0.10 kg / L to 0.70 kg / L, preferably 0.20 kg / L to 0.60 kg / L, preferably 0.30 kg / L to 0.55 kg / L, and preferably 0.40 kg / L to 0.50 kg / L.

[0043] A-3. Binder (C) As described above, the spherical polymer microparticles (A) and the transparent polymer powder (B) are bound together by the binder (C) to form the powder granules. It is preferable to form the powder granules using a small amount of binder (C). Forming the powder granules using a small amount of binder (C) is advantageous in that it can produce powder granules with excellent heat resistance and discoloration resistance. The shape of the spherical polymer microparticles (A) contributes to a decrease in binding strength. However, according to the present invention, a favorably bound powder granule can be obtained even with a reduced binder content, which is advantageous from the standpoints of cost, dispersibility, and colorability. The binder (C) preferably has excellent heat stability (minimum deterioration at the resin processing temperature) and color stability (resistance to heat discoloration and light discoloration). As described above, the binder (C) is composed of an aqueous polymer (preferably a colorless, transparent polymer or aqueous dispersion).

[0044] As described above, the content of the binder (C) is 2 to 30 parts by mass (dry mass) relative to 100 parts by mass of the powder granules. The content of the binder (C) is preferably 3 to 25 parts by mass, more preferably 4 to 20 parts by mass, relative to 100 parts by mass of the powder granules. Within this range, a powder granule with excellent dispersibility and little coloration can be obtained.

[0045] Examples of the aqueous polymer constituting the binder (C) include acrylic resins, polyester resins, polyurethane resins, etc. These resins may be used alone or in combination of two or more. By using the above resins, it is possible to obtain a powder granulated product that is excellent in dispersibility, optical properties, handleability, and breaking strength.

[0046] The binder (C) includes a polymer having a hydrophilic group (hydrophilic unit) and a hydrophobic group (hydrophobic unit). The polymer binder (C) preferably has a polymer structure capable of binding a powder mixture consisting of component (A) and component (B), and optionally other components, with high binding strength. In other words, the powders constituting the powder granules can be hydrophilic powders, hydrophobic powders, or a mixture of various powders possessing both hydrophilic and hydrophobic properties. Therefore, the polymer binder (C) preferably has both hydrophilic and hydrophobic groups in its polymer structure. Specific examples of polymers having hydrophilic groups in their polymer structure include polymers having an acrylic or methacrylic ester bond structure, an ester bond structure, a urethane bond structure, or an amide bond structure within their structure. Hydrophobic groups include, for example, hydrocarbon structures.

[0047] The weight-average molecular weight of the polymer constituting the binder (C) is preferably 10,000 to 500,000, more preferably 20,000 to 300,000, even more preferably 30,000 to 200,000, and particularly preferably 30,000 to 100,000. Within these ranges, a powder granule with excellent breaking strength can be obtained. A weight-average molecular weight of 10,000 or more can further increase the binding force. Furthermore, during the granulation process, the binder (C) fluidizes and blends easily with the surfaces of the components constituting the powder granule, which can be advantageous in increasing the breaking strength of the powder granule.

[0048] The softening temperature (glass transition temperature or melting point) of the polymer constituting the binder (C) is preferably −30° C. to 80° C., more preferably −20° C. to 70° C., and even more preferably −15° C. to 65° C. If it is within this range, a binder (C) with excellent binding strength can be obtained.

[0049] In one embodiment, the polymer constituting the binder (C) is an aqueous polymer (it can be used in the form of an aqueous polymer). The use of an aqueous polymer makes it possible to obtain a high binding force even for spherical polymer microparticles that are difficult to bind due to their shape. The aqueous polymer can be used in the form of an aqueous solution or an aqueous dispersion (emulsion or suspension) containing a polymer (preferably with a median diameter (D50) of 1 μm or less). The use of such an aqueous polymer can uniformly and thinly coat the surfaces of the components constituting the powder granules, thereby producing a powder granule with excellent breaking strength. The method for blending the aqueous polymer liquid will be described in detail below; however, it is preferable to blend the aqueous polymer liquid in small amounts with the mixed powder particles of component (A) and component (B) so that it spreads throughout the particles.

[0050] In the aqueous dispersion, the median diameter (D50) of the aqueous polymer is preferably 0.1 μm to 1 μm, more preferably 0.1 μm to 0.8 μm, even more preferably 0.1 μm to 0.7 μm, and particularly preferably 0.1 μm to 0.5 μm. In one embodiment, the median diameter (D50) of the aqueous polymer is 0.5 μm or less. The average particle diameter of primary particles is measured using the Coulter counter method. The median diameter (D50) of the aqueous polymer referred to here is the particle diameter of the raw material powder granules, and is the median diameter of component (C) in the aqueous dispersion. After the powder granules are formed, the aqueous polymer (C) is usually not in a granular form, and the binder (C) is present in a uniform, thin coating between components (A) and (A), between components (B) and (B), or between components (A) and (B), binding the components together.

[0051] The refractive index of the binder (C) is preferably 1.46 to 1.59. The refractive index of the binder (C) can be appropriately selected depending on the refractive index of the thermoplastic resin to be blended. Furthermore, when the "polymer binder (C)" according to this embodiment is required to function as a light diffusing agent, the refractive index thereof is preferably matched to the refractive index of the thermoplastic resin used as the base polymer, for example, approximately 1.57 for polycarbonate resin and approximately 1.49 for acrylic resin, and can be appropriately selected.

[0052] Commercially available products can be used as the binder (C). The acrylic aqueous dispersion can be appropriately selected from, for example, the "Saibinol (registered trademark)" series of Saiden Chemical Co., Ltd. The polyester aqueous solution can be appropriately selected from, for example, the "Pluscoat (registered trademark)" series of Goo Chemical Industry Co., Ltd. The polyurethane aqueous dispersion can be appropriately selected from, for example, the "Hydorsize (registered trademark)" series of Michelman Corporation.

[0053] A-4. Other ingredients The powder granules may contain any other suitable powder additives as needed. Examples of additive powders include antioxidants, light stabilizers, UV absorbers, heat stabilizers, impact modifiers, antibacterial agents, dispersants, compatibilizers, processing aids, lubricants, coupling agents, and hydrolysis inhibitors. These may also be liquid additives. The additive powders are blended in small amounts (usually a few mass % or less).

[0054] In one embodiment, a dispersant may be used as the additive powder (however, dispersants containing phosphorus, nitrogen, sulfur, metals, etc., which may cause coloring, and dispersants with poor heat resistance are excluded).

[0055] The dispersant may provide benefits such as improving the productivity (discharge rate) of powder granules, reducing frictional heat during granulation, and improving the ease of cleaning the granulation equipment.

[0056] In one embodiment, the dispersant that can be preferably used is at least one selected from the group consisting of polyhydric alcohol fatty acid esters, polyglycerin fatty acid esters, condensed hydroxy fatty acids, and alcohol esters of condensed hydroxy fatty acids. These dispersants can exhibit excellent properties in the final resin composition, such as excellent heat resistance stability, little residual coloration, maintaining the transparency and molecular weight reduction of the base polymer, suppressing heat generation during melt-kneading, and keeping degradation due to processing to a low level.

[0057] The polyhydric alcohol fatty acid ester is an ester compound composed of a polyhydric alcohol and a fatty acid. Examples of the polyhydric alcohol fatty acid ester include esters of polyhydric alcohols such as pentaerythritol and glycerin with fatty acids having 8 or more carbon atoms (preferably 8 to 24 carbon atoms, more preferably 10 to 22 carbon atoms).

[0058] The polyglycerol fatty acid ester is an ester compound composed of polyglycerol and a fatty acid, and examples of the polyglycerol fatty acid ester include diglycerol palmitate, diglycerol stearate, diglycerol oleate, decaglycerol palmitate, decaglycerol stearate, and decaglycerol oleate.

[0059] The content of the dispersant is usually 0.01% by mass to 10% by mass, preferably 0.1% by mass to 7% by mass, and more preferably 0.3% by mass to 5% by mass, based on the total amount of the powder granulated product.

[0060] B. Manufacturing method of powder granulation The powder granules can be produced by any suitable method, for example, a compressed granule of a mixture containing spherical polymer fine particles (A), transparent polymer powder (B), and a binder (C).

[0061] In one embodiment, the method for producing the powder granulation product includes a mixing step of mixing spherical polymer microparticles (A), transparent polymer powder (B), and a binder (C) to obtain a powder mixture; a granulation step of compressing and granulating the powder mixture to obtain a powder granulation precursor; and a heating step of heating the powder granulation precursor.

[0062] In the mixing step, the spherical polymer fine particles (A) and the transparent polymer powder (B) may be mixed in advance, and then the binder (C) may be further mixed therein.

[0063] Water may be further added in the mixing step. By uniformly dispersing water in small amounts throughout the mixture at an appropriate blending ratio, granulation in the granulation step can be stabilized, and granules with excellent shape and granule hardness can be obtained.

[0064] In one embodiment, the binder (C) is mixed in the form of an aqueous solution of a water-based polymer or an aqueous dispersion (emulsion or suspension) containing a water-based polymer (for example, with a median diameter (D50) of 1 μm or less). By using an aqueous polymer in this way, the surfaces of the powder granule constituent components (spherical polymer particles (A), transparent polymer powder (B), etc.) can be uniformly and thinly coated overall, resulting in a powder granule with excellent breaking strength. The water-based polymer liquid is preferably added in small amounts to a mixture of the spherical polymer particles (A) and transparent polymer powder (B) so as to be spread throughout.

[0065] In one embodiment, the binder (C) may be gradually added in the form of a spray, a shower, or drips using a nozzle. Here, "spray" refers to a state in which a liquid pressurized by gas such as compressed air is suddenly ejected from a fine nozzle hole, resulting in liquid particles. Furthermore, "shower" refers to a state in which a fluid is dispersed and ejected from a showerhead (a jig with multiple equally sized holes) under the same pressure. The water to be added is not particularly limited, and examples thereof include tap water, distilled water, ion-exchanged water, hard water, and soft water. If necessary, water may be used in combination with other components such as alcohol to improve wettability to the powder raw material. When other components (e.g., solid components) are added, the components may be mixed with the mixture.

[0066] In the mixing step, it is preferable to use any appropriate mixer to achieve uniform mixing. Examples of mixers include a Henschel mixer, a powder kneader (KDH, KDA, CKD, CPM) (Dalton), a Spartan mixer (SPM) (Dalton), and an SP granulator (SPG) (Dalton). From the perspective of producing a mixture with excellent granulation properties, when using a Henschel mixer, it is preferable to use a combination of upper and lower blades, with the upper blade being a Y1 blade (trade name, manufactured by Nippon Coke and Engineering Co., Ltd.) and the lower blade being an S0 blade (trade name, manufactured by Nippon Coke and Engineering Co., Ltd.). It is also preferable to install a deflector in the stirring vessel and perform mixing. In other words, by using a mixing step that allows each component to be uniformly dispersed throughout the mixture, it is possible to improve productivity and quality stability in the granulation step and obtain granules with excellent shape and granule hardness.

[0067] The mixing time in the mixing step can be any appropriate time depending on the types of components, the type of mixer, the component blending ratio, etc. Preferably, the mixing time is set so that the surfaces of component (A) and component (B) are sufficiently and uniformly coated with the binder (component (C)). A high-speed mixer such as a Henschel mixer or a Spartan mixer can be used for processing in 1 to 10 minutes. On the other hand, a powder kneader may require processing times of several minutes to 60 minutes.

[0068] The amount of water blended in the mixing step can be any appropriate amount depending on the properties of the powder (such as water absorption). The amount of water blended in the mixing step is, for example, 5 to 100 parts by mass, preferably 8 to 70 parts by mass, relative to 100 parts by mass of the total amount of the powder mixture of the spherical polymer fine particle powder (A) and the transparent polymer powder (B). This range can be advantageous in producing a powder granulation precursor with excellent granulation properties uniformly and at a high granulation production rate in the granulation step while suppressing excessive heat generation. Blending a small amount of water is preferable in terms of reducing the amount of carbon dioxide generated, as it can reduce the amount of energy required in the drying step.

[0069] The time for adding water in the mixing step is, for example, 1 to 60 minutes, preferably 3 to 30 minutes, and more preferably 5 to 20 minutes.

[0070] In the granulation step, a semi-wet granulation method can be used as the compression granulation method. Examples of compression granulation methods / semi-wet granulation methods include the disc pelleting method, tableting method, and briquetting method. From the viewpoint of balancing productivity and the quality of the obtained powder granules, the disc pelleting method is preferably used. More specifically, disc pelleting methods include the roller-disc die method, roller-ring die method, double die method, and flat die method. An example of a commercially available disc pelleting method granulator is the Disc Pelletter F Series manufactured by Dalton.

[0071] A disc pelletizer has, for example, a disc plate with a large number of holes of 1 mm to 30 mm and a roller for pressure-feeding raw material through the holes in the disc plate. The raw material (powder mixture containing moisture) supplied between the disc plate and the roller is forced into the holes in the disc as the roller rotates, forming a roughly cylindrical or roughly prismatic extrudate. The extruded powder granulation precursor is cut on the back surface of the disc with a cutter or the like to obtain pellet-shaped powder granulation. The length of the powder granulation precursor can be adjusted by the distance between the back surface of the disc and the cutter and the rotation speed of the roller. The distance between the disc plate and the cutter can be any appropriate distance depending on the type of powder raw material, etc. The distance between the disc plate and the cutter is, for example, 1 mm to 30 mm, more preferably 2 mm to 20 mm, and even more preferably 3 mm to 10 mm.

[0072] The heating step removes moisture from the powder granule precursor and also increases the binding strength of the powder granule.

[0073] Any appropriate heating method can be used in the heating step. As described above, the heating step promotes the binding of the powder granules. The heating temperature is, for example, 50°C to 200°C, preferably 80°C to 180°C, and more preferably 100°C to 150°C.

[0074] In one embodiment, the heating temperature in the heating step is equal to or higher than the softening temperature of the binder (C). Here, the softening temperature refers to the glass transition temperature or melting point. The difference between the heating temperature in the heating step and the softening temperature of the binder (C) is, for example, 1°C to 100°C, preferably 10°C to 80°C, and more preferably 20°C to 60°C.

[0075] In the heating step, any appropriate heating (drying) equipment can be used. For example, a vibration fluidized dryer is preferred because it can dry efficiently in a short time, and examples thereof include the VDF series vibration fluidized dryers manufactured by Dalton. After the heating step, a powder granulated product from which fine powder has been removed can be obtained by processing using a vibrating sieve or the like.

[0076] Compared with conventional methods for obtaining a masterbatch by melt-blending using a melt-kneading device, typically a twin-screw extruder, the powder granules according to the embodiments of the present invention can control the concentration of the spherical polymer microparticles (A) over a wide range and can be continuously produced at a high production rate. Furthermore, compared with melt-kneading methods, typically a twin-screw extruder, the total amount of electricity used to obtain the granules can be significantly reduced. High-concentration granules can significantly reduce packaging and transportation costs.

[0077] C. Melt compounding of powder granulation materials In one embodiment, the powder granules are used as a raw material for a thermoplastic resin compound. Also provided is a melt compound of the powder granules and a thermoplastic resin (a thermoplastic resin to which the powder granules are applied). Any thermoplastic resin can be used as the thermoplastic resin. Examples of the thermoplastic resin include styrene-based resins, acrylic-based resins, styrene-methacrylate-based resins, polycarbonate-based resins, and alicyclic polyolefin-based resins. The thermoplastic resin is preferably a transparent resin.

[0078] The ratio (nP / nB) of the refractive index nB of the transparent polymer powder (B) to the refractive index nP of the thermoplastic resin to which the powder granules are applied is preferably 0.8 to 1.2, more preferably 0.85 to 1.15, even more preferably 0.9 to 1.1, and particularly preferably 0.95 to 1.05. In one embodiment, the transparent polymer powder (B) may be the same type as the thermoplastic resin to which the powder granules are applied, and nP / nB may be 1.

[0079] Any suitable method can be used to produce the molten compound. For example, a kneader, a Banbury mixer, a roll, or a single-screw or multi-screw extruder having two or more screws can be used. A twin-screw extruder is preferably used. The composition obtained by melt-kneading is pelletized.

[0080] By using the above-mentioned powder granulation product as a masterbatch, it is possible to provide a melt compound that can produce resin compositions containing spherical polymer microparticles at various desired concentrations with high precision, high productivity, and stability, while also improving safety against dust explosions and allowing for a good working environment. The resulting resin composition also exhibits good quality, including good dispersibility of the spherical polymer microparticles, good color tone, and good optical properties (light diffusion and transmittance). In one embodiment, the above-mentioned powder granulation product can be directly added as a masterbatch to a resin processing device such as an injection molding machine or an extrusion molding machine to obtain various resin composition molded products. [Example]

[0081] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Parts and percentages are based on mass unless otherwise specified.

[0082] [Example 1] Production of powder granules FM Mixer (manufactured by Nippon Coke & Engineering Co., Ltd., product name "5FM5C / I"; processing volume: 5 L) 75 parts by mass of spherical polymer microparticles A-1 (polymethylsilsesquioxane-based crosslinked particles, manufactured by Aica Kogyo Co., Ltd., trade name "Ganzpearl SI-020") and 25 parts by mass of transparent polymer powder B-1 (manufactured by Asahi Kasei Corporation, trade name "Delpowder 60N") were added to the mixture, and the mixture was stirred for 2 minutes at a stirring blade rotation speed of 1,000 rpm to obtain a powder mixture. The FM mixer blades consisted of a combination of upper and lower blades, with the upper blade being a Y1 blade (trade name, manufactured by Nippon Coke and Engineering Co., Ltd.) and the lower blade being an S0 blade (trade name, manufactured by Nippon Coke and Engineering Co., Ltd.) A baffle plate was also installed inside the mixing vessel. While rotating the stirring blade at 2,000 rpm, a mixture of 15 parts by mass of binder C-1 (manufactured by Saiden Chemical Industry Co., Ltd., product name "Saibinol CA-200", acrylic resin-based aqueous dispersion, median diameter (D50): 0.12 μm, solid content: 49%) and 10 parts by mass of tap water was added to 100 parts by mass of the above powder mixture, and stirred for 15 minutes to obtain a powder mixture to which the binder had been added. The temperature of the powder mixture was 50°C. This powder mixture was charged into a disc pelleter (manufactured by Dalton, trade name "Disc Pelleter F-5 / 11-175") to obtain a pellet-shaped granulated product precursor. In this case, the diameter of the die hole was 3 mm, the thickness of the die plate was 15 mm, the effective length of the die hole was 10 mm, and the rotation speed of the roller of the dispelleter was 108 rpm. The obtained granule precursor was dried at 100°C for 6 hours using a hot air circulation dryer to obtain granules (PG-1). The powder granules had a bulk density of 0.47 kg / L, a moisture content of 0.28% by mass, and a granule breaking strength of 1.0 kg, demonstrating excellent handleability. A photograph of the appearance of the obtained powder granules (PG-1) is shown in Figure 1. A photograph of the cross section of the obtained powder granules (PG-1) is shown in Figure 2.

[0083] [Examples 2 to 5, Comparative Examples 1 to 6] Powder granules were obtained in the same manner as in Example 1, except that the spherical polymer particles, transparent polymer powder, and binder shown in Table 1 and below were used in the amounts shown in Table 2. Comparative Example 1 is an example using only spherical polymer particles "A-1," but granulation was not possible. Comparative Example 2 is an example using the same binder as Example 1, but granulation was not possible. Comparative Example 3 is an example using binder "C-3," which does not meet the requirements of the present invention, but the breaking strength was significantly poor. Comparative Example 4 is an example using spherical polymer particles "A-1" without transparent polymer powder (B-1), but granulation was not possible due to die clogging. Comparative Example 5 is an example using the same binder as Example 5, but granulation was significantly poor. Comparative Example 6 is an example using 1.2 mass% of binder (C-2) (outside the range of the present invention), but the breaking strength was significantly poor and insufficient.

[0084] Comparative Example 7: Production and evaluation of a high-concentration spherical polymer masterbatch by melt kneading 70 parts by mass of spherical polymer particles "Ganzpearl SI-020 (A-1 in Table 1)" and 30 parts by mass of transparent polymer powder B-1 (manufactured by Asahi Kasei Corporation, product name "Delpowder 60N") were premixed by hand shaking, and the mixture was fed through a hopper attached to the most upstream part of an 18 mm twin-screw extruder (manufactured by Shibaura Machine Co., Ltd., model "TEM18-SS, L / D=50") and continuously melt-kneaded. The cylinder temperature of the extruder was set to 150°C just below the hopper, gradually increasing to 230°C up to the middle section, and then kept at 230°C from the middle section onwards. The screw rotation speed of the extruder was 100 rpm. Although melt-kneading was started at a low feed rate of 1 to 2 kg / hr, the extruder overloaded immediately after the feed, making continuous melt-kneading impossible. In other words, a melt-kneaded granule containing 70% by mass of crosslinked spherical polymer particles could not be obtained.

[0085] [Table 1] Component (A): spherical polymer particles (A-1) "Ganz Pearl SI-020 (trade name)" manufactured by AICA Kogyo Co., Ltd. (polymethylsilsesquioxane-based crosslinked particles, median diameter (D50): 2.0 μm, bulk density: 0.4 kg / L, refractive index: 1.41, sphericity: 1.02, angle of repose: 30°) (A-2) "Techpolymer MBX-8 (trade name)" manufactured by Sekisui Plastics Co., Ltd. (methyl methacrylate polymer-based crosslinked particles, median diameter (D50): 8.0 μm, bulk density: 0.6 kg / L, refractive index: 1.49, sphericity: 1.00, angle of repose: 20°) (A-3) "Techpolymer MBX-5 (trade name)" manufactured by Sekisui Plastics Co., Ltd. (methyl methacrylate polymer-based crosslinked particles, median diameter (D50): 5.0 μm, bulk density: 0.5 kg / L, refractive index: 1.49, sphericity: 0.99, angle of repose: 15°) Component (B): Transparent polymer powder (B-1) "Delpowder 60N (trade name)" manufactured by Asahi Kasei Corporation (polymethyl methacrylate granules, median diameter (D50): 200 μm, bulk density: 0.85, refractive index: 1.49, softening temperature: 90°C (Vicat softening point) (B-2) "YS Resin SX-100 (trade name)" manufactured by Yasuhara Chemical Co., Ltd. (polystyrene granules, median diameter (D50): 300 μm (ground using an FM mixer), bulk density: 0.60, refractive index: 1.59, softening temperature: 62°C (measured by DSC, glass transition temperature) Component (C): Binder (C) (C-1) Saibinol CA-200 (trade name) manufactured by Saiden Chemical Co., Ltd. (acrylic resin-based aqueous dispersion, median diameter (D50): 0.12 μm, solid content: 49%, softening point (glass transition point): −10° C.) (C-2) "Pluscoat Z-561 (trade name)" manufactured by GOO Chemical Industry Co., Ltd. (water-soluble polyester, solid content: 25%, refractive index: 1.57, molecular weight: approximately 27,000) (C-3) "CHEMIPEARL A100 (trade name)" manufactured by Mitsui Chemicals, Inc. (water-soluble polyolefin dispersion, solid content: 40%, median diameter (D50): 4 μm (used in Comparative Example 3)

[0086] [Table 2]

[0087] <Evaluation> The obtained powder granules were subjected to the following evaluations, and the results are shown in Table 3. (1) Granulation property (possibility of granulation) The obtained powder granules were checked and the granulation properties were evaluated according to the following criteria. Good: Powder granules with a diameter of 2.8 to 3.5 mm are obtained. ×: The powder raw material lacks cohesion, and powder granules cannot be obtained. Or, granules cannot be obtained stably due to clogging of the die. The temperature in the granulation process was measured by measuring the temperature of the granules immediately after granulation using a thermocouple. (2) Granulation speed The production rate of powder granules per hour (kg / Hr) was calculated. (3) Bulk density The dried powder granules were allowed to fall naturally into a 1-liter measure, filled to the brim, and weighed to a volume of exactly 1 liter. The mass was then measured to calculate the bulk density (unit: kg / L) of the powder granules. (4) Granule (pellet) size 25 particles of the powder granules were taken out, and the length and diameter of the particles were measured using a vernier caliper, taking the average value of the 25 particles. (5) Moisture content The amount of moisture (unit: mass %) remaining in the powder granules was measured using an infrared moisture meter (FD-660 manufactured by Kett Electric Laboratory). (6) Breaking strength The breaking strength (unit: kg) of the powder granules was measured using a Kiya hardness tester (manufactured by Shiro Sangyo Co., Ltd., product name "WPF1600-B") The measured value was the average value of 25 particles of the powder granules. (7)Angle of repose The angle of repose (°) was measured using a repose angle measuring instrument (manufactured by AS ONE Corporation, trade name "Repose Angle Measuring Instrument").

[0088] [Table 3]

[0089] [Reference Example 6] Production and evaluation of reference resin composition One part by weight of spherical polymer microparticles "Ganzpearl SI-020" (A-1 in Table 1) and 99 parts by weight of acrylic resin pellets (Asahi Kasei Corporation's "Delpet 60N") were premixed by handshaking and then fed into a 40mm single-screw extruder (Isuzu Chemical Engineering Co., Ltd., model "SV-40-32-EXT", L / D = 32, with a dull end) via a hopper attached to the upstream end for continuous melt-kneading. The extruder cylinder temperature was set at 150°C immediately below the hopper, gradually increasing to 230°C up to the middle section, and then maintained at 230°C from the middle section onwards. The extruder screw rotation speed was 100 rpm. The molten mixture was continuously extruded in the form of a strand, which was then cooled in a strand bath (water temperature: 40°C) to produce pellets having a diameter of 3 mm and an average length of 3 mm. In Reference Example 6, since separation of the spherical polymer particles (A-1) and the acrylic resin pellets occurred during long-term operation, the pellets were homogenized by post-blending after pelletization. The acrylic resin composition of the resin composition (containing 1% by mass of A-1) was placed into an injection molding machine (manufactured by Toyo Machinery & Metal Co., Ltd., product name "Si-80IV"), and a business card-sized molded body in the shape of a three-tiered plate (80 mm x 50 mm x 1, 2, and 3 mm thick) was obtained at a cylinder setting temperature of 230°C, a mold temperature of 60°C, and a cooling time of 15 seconds. The obtained molded body was used to measure the total light transmittance (%), parallel transmittance (%), diffuse transmittance (%), and haze (%) at a thickness of 1 mm using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH5000"). In addition, for the same molded body, a color difference meter (manufactured by Konica Minolta, Inc., product name "CM-3600d") was used to measure the L * , a * , b * , and numerical measurements were carried out for each. The "color / optical properties" in Table 4 were evaluated according to the following criteria, using the results shown in Reference Example 6 as the standard. Good: ΔE value is less than 0.7 ×: ΔE value exceeds 0.7 Furthermore, "Dispersion" in Table 4 is the result of visually observing the dispersibility of the spherical polymer particles at a location 1 mm thick in the molded product, and was evaluated according to the following criteria. Good: Dispersion is good, and no agglomerates of spherical polymer particles are observed. ×: Aggregates of spherical polymer particles are present.

[0090] [Example 7] Production and evaluation of resin composition using "powder granules" 1.45 parts by mass of the powder granulation product (PG-1) obtained in Example 1 and 98.55 parts by mass of acrylic resin pellets ("Delpet 60N" manufactured by Asahi Kasei Corporation) (not powder B-1) were premixed by hand shaking, and the composition was adjusted so that the composition concentration of "Ganzpearl SI-020 (A-1)" in the final composition was 1 mass%, the same as in "Reference Example 6." Melt-kneading was carried out in the same manner as in Reference Example 6 to produce pellets of the resin composition. Example 7 achieved stable kneading and extrusion speed, and the production stability was extremely excellent. That is, in Example 7, even during long-term operation, separation of the spherical polymer particles (A-1) and the acrylic resin pellets "Delpet 60N" did not occur, and a resin composition with a stable composition could be continuously obtained, so that post-blending treatment after pelletization was not necessary. An injection-molded article was prepared from the obtained pellets of the resin composition in the same manner as in Reference Example 6, and the optical properties and dispersibility were evaluated. As shown in Table 4, results equivalent to those of Reference Example 6 were obtained.

[0091] [Example 8] Melt-kneading was carried out in the same manner as in Example 7 to prepare pellets of a resin composition, except that the powder granules "PG-3" obtained in Example 3 were used instead. In Example 8, stable kneading and discharge speed were obtained, and production stability was extremely excellent. In Example 8, as in Example 7, separation of the spherical polymer particles (A-1) and the acrylic resin pellets did not occur even during long-term operation, and a resin composition with a stable composition could be continuously obtained, so that post-blending treatment after pelletization was not necessary. An injection-molded article was prepared from the obtained pellets of the resin composition in the same manner as in Reference Example 6, and the optical properties and dispersibility were evaluated. As shown in Table 4, results equivalent to those of Reference Example 6 were obtained.

[0092] [Table 4]

[0093] [Reference Example 9] Production and evaluation of reference resin composition One part by mass of spherical polymer particles "Techpolymer MBX-8 (A-2 in Table 1)" and 99 parts by mass of polycarbonate resin pellets (manufactured by Covestro under the trade name "Makrolon 2400") were premixed by hand shaking, and the mixture was continuously melt-kneaded into the same 40 mm single-screw extruder as in Reference Example 6, by feeding it through a hopper attached to the most upstream section. The cylinder temperature of the extruder was set to 230°C just below the hopper, gradually increasing up to 280°C up to the middle section, and then kept at 280°C from the middle section onwards. The screw rotation speed of the extruder was 100 rpm. The molten mixture was continuously extruded in the form of a strand, which was then cooled in a strand bath (water temperature: 40°C) to produce pellets having a diameter of 3 mm and an average length of 3 mm. In Reference Example 9, as in Reference Example 6, separation of the spherical polymer microparticles (A-2) and the polycarbonate resin pellets occurred during long-term operation, so after pelletization, the pellets were homogenized by post-blending. The polycarbonate resin composition (containing 1% by mass of A-2) of this resin composition was used in the same injection molding machine as in Reference Example 6 to produce a business card-sized three-tiered plate-shaped molded body at a cylinder setting temperature of 280°C, a mold temperature of 80°C, and a cooling time of 15 seconds, and the optical properties and dispersibility were evaluated in the same manner as in Reference Example 6. The "color / optical properties" in Table 5 are based on Reference Example 9.

[0094] [Example 10] Production and evaluation of resin composition using powder granules 1.43 parts by mass of the powder granulation product "PG-4" obtained in Example 4 and 98.57 parts by mass of the polycarbonate resin pellets used in Reference Example 9 ("Makrolon 2400" manufactured by Covestro) were premixed by hand shaking, and the composition was adjusted so that the composition concentration of "Techpolymer MBX-8 (A-2)" in the final composition was 1% by mass, the same as in Reference Example 9. Melt-kneading was carried out in the same manner as in Reference Example 9 to produce pellets of the resin composition. In Example 10, stable kneading and extrusion speed were obtained, and production stability was extremely excellent. That is, in Example 10, a resin composition with a stable composition could be continuously obtained even during long-term operation, and therefore post-blending treatment after pelletization was not necessary. An injection-molded article was prepared from the obtained pellets of the resin composition in the same manner as in Reference Example 9, and the optical properties and dispersibility were evaluated. As shown in Table 5, results equivalent to those of Reference Example 9 were obtained.

[0095] [Table 5]

Claims

1. A powder granulation product comprising spherical polymer fine particles (A), transparent polymer powder (B), and a binder (C), the content of the spherical polymer fine particles (A) is 10 parts by mass to 97 parts by mass per 100 parts by mass of the powder granules, the content of the transparent polymer powder (B) is 1 part by mass to 88 parts by mass relative to 100 parts by mass of the powder granules, the content of the binder (C) is 2 parts by mass to 30 parts by mass (dry mass) per 100 parts by mass of the powder granules, the binder (C) contains an aqueous polymer, The water-based polymer has a hydrophilic group and a hydrophobic group. Powder granules.

2. 2. The powder granule according to claim 1, wherein the material constituting the spherical polymer fine particles (A) is at least one selected from the group consisting of crosslinked acrylic resins, crosslinked styrene resins, crosslinked acrylic-styrene resins, crosslinked silicone resins, crosslinked silicone-acrylic resins, melamine resins, and benzoguanamine resins.

3. 2. The powder granulated product according to claim 1, wherein the ratio (b / a) of the minor axis b of the spherical polymer particles (A) to the major axis a of the spherical polymer particles (A) is 0.9 or more.

4. 2. The powder granulation product according to claim 1, wherein the median diameter (D50) of the spherical polymer fine particles (A) is 0.1 μm to 300 μm.

5. 2. The powder granulation product according to claim 1, wherein the spherical polymer fine particles (A) have a bulk density of 0.05 kg / L to 1.0 kg / L.

6. 2. The powder granulation product according to claim 1, wherein the refractive index of the spherical polymer fine particles (A) is 1.40 to 1.

70.

7. 2. The powder granulation product according to claim 1, wherein the material constituting the transparent polymer powder (B) is one or more selected from the group consisting of styrene-based resins, acrylic-based resins, styrene-methacrylate-based resins, polycarbonate-based resins, polyester-based resins, polyurethane-based resins, petroleum resins, terpene-based resins, and alicyclic polyolefin-based resins.

8. The powder granule according to claim 1, wherein the transparent polymer powder (B) has a median diameter (D50) of 1 μm to 3000 μm.

9. The powder granule according to claim 1, wherein the refractive index of the transparent polymer powder (B) is 1.45 to 1.

65.

10. 2. The powder granule according to claim 1, wherein the transparent polymer powder (B) has a bulk density of 0.10 kg / L to 0.70 kg / L.

11. The powder granulated product according to claim 1, wherein the median diameter (D50) of the aqueous polymer is 0.5 μm or less.

12. 2. The powder granulated product according to claim 1, wherein the aqueous polymer is at least one selected from the group consisting of acrylic resins, polyester resins, and polyurethane resins.

13. 2. The powder granulated product according to claim 1, which has a breaking stress of 0.3 kg or more as measured by a Kiya hardness tester.

14. The powder granulated product according to claim 1, having a bulk density of 0.3 kg / L to 1.0 kg / L.

15. The powder granulated product according to claim 1, wherein the median diameter (D50) is 1 mm to 10 mm.

16. The powder granulated product according to claim 1, which has a substantially cylindrical or substantially prismatic shape.

17. a mixing step of mixing the spherical polymer fine particles (A), the transparent polymer powder (B), and the binder (C) to obtain a powder mixture; A granulation step of compressing and granulating the powder mixture to obtain a powder granulation precursor; and a heating step of heating the powder granulated product precursor; A method for producing the powder granulated product according to any one of claims 1 to 16.

18. The method for producing a powder granulated product according to claim 17, wherein the compression granulation method in the granulation step is a disc pelletizer method.

19. the binder (C) contains a water-based polymer, the mixing step includes adding an aqueous solution containing a water-based polymer or an aqueous dispersion containing a water-based polymer; A method for producing the powder granulated product according to claim 17.

20. Use of the powder granules according to any one of claims 1 to 16 as a raw material for a compound containing a thermoplastic resin or as a molding material.

21. Use of the powder granulated material described in claim 20 as a raw material for a thermoplastic resin compound containing one or more thermoplastic resins selected from the group consisting of styrene-based resins, acrylic-based resins, styrene-methacrylate-based resins, polycarbonate-based resins, and alicyclic polyolefin-based resins.

22. Use of the powder granules according to claim 20, wherein the ratio (nP / nB) of the refractive index nB of the transparent polymer powder (B) to the refractive index nP of the thermoplastic resin is 0.8 to 1.2.

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