JP2012170913A - Method for producing single crystal nanodiamond granulated powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing single crystal nanodiamond granulated powder and a resin composition of a high refractive index which can be obtained by dispersing high-concentration of ultrafine particles of the single crystal nanodiamond granulated powder in an organic substance such as a resin.SOLUTION: The single crystal nanodiamond granulated powder can be produced by a step of pulverizing a single crystal nanodiamond aggregate of a cluster shape having a specific surface area of ≥300 m/g and/or primary particle size of 1 to 10 nm using a media stirring type wet pulverizer, a step of preparing slurry of predetermined concentration by mixing at least a binder and a dispersion medium with pulverized powder and a step of supplying the slurry to a spray drier to dry the slurry by spray drying.

Description

The present invention relates to a resin composition containing a single crystal nanodiamond granulated powder obtained by a method for producing a single crystal nanodiamond granulated powder.

Conventionally, in order to increase the refractive index of the surface of a substrate such as transparent plastic or glass, a transparent resin film, a transparent resin sheet, or a transparent resin molded product, inorganic oxide fine particles having a high refractive index are added to the resin as a binder. Many methods for increasing the refractive index by mixing them into a composite resin composition have been adopted. The inorganic oxide fine particles used here are used to make the composite resin composition have a high refractive index. As the inorganic oxide fine particles, for example, in Patent Document 1, selected from the group consisting of Ti, Fe, Cu, Zn, Y, Zr, Nb, Mo, In, Sn, Sb, Ta, W, Pb, Bi, and Si. In addition, metal oxide fine particles made of one or more metals are used. Among these, titanium oxide fine particles are a preferable high refractive index material because they have the highest refractive index and are chemically stable.

Titanium oxide includes a rutile type and an anatase type as typical crystal types, and anatase type titanium oxide fine particles have been mainly used in conventional high refractive index materials. However, the anatase-type titanium oxide fine particles have high photoactivity due to ultraviolet absorption and have a function as a photocatalyst. Therefore, when mixed with an organic resin, the resin deteriorates due to ultraviolet rays, resulting in durability. There was a problem of being inferior. On the other hand, for the purpose of improving the durability of the resin composition containing anatase-type titanium oxide ultrafine particles, for example, ultrafine particles combining anatase-type titanium oxide and an inorganic oxide as described in Patent Document 1, or anatase-type Ultrafine particles obtained by coating titanium oxide with an inorganic oxide and sol liquids thereof are applied.

Although the light resistance is improved by coating the titanium oxide fine particles with the inorganic oxide in this manner, the light stability over a long period of time such as discoloration, fading, and a decrease in hardness due to deterioration of surrounding organic substances cannot be satisfied. . Moreover, when it coat | covers with an oxide, a refractive index will fall significantly and the effect which improves the refractive index of a resin composition is low. Furthermore, there was a problem that coloring was observed depending on the metal used.

In recent years, rutile type titanium oxide fine particles have attracted attention as a high refractive index material replacing the anatase type titanium oxide fine particles, and various proposals have been made. Since the rutile titanium oxide fine particles are excellent in coloring power and hiding power, they have long been used as white pigments in various fields such as chemical fibers, inks, paints, cosmetics and pharmaceuticals. . Patent Document 2 proposes rutile-type titanium oxide ultrafine particles having a coating layer made of silicon oxide. However, since the rutile-type titanium oxide fine particles contain metal oxide components other than titanium oxide, there is a problem that coloring is observed depending on the metal used. Furthermore, since the appearance of the rutile-type titanium oxide fine particles is in a fibrous form, when mixed into the resin composition, a thixotropic flow is developed and its handling becomes difficult. In contrast, there are no ultrafine particles and sol liquid that have a high refractive index and are chemically stable.

JP 2001-123115 A JP 2007-270097 A

An object of the present invention is to provide a high refractive index resin composition in which a single crystal nanodiamond granulated powder having a high refractive index and excellent dispersibility, light resistance, weather resistance, durability and the like is dispersed. .

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found a granulated powder that simultaneously satisfies the above-mentioned performance and completed the present invention.
That is, the present invention
(1) A step of pulverizing a cluster-like single crystal nanodiamond aggregate having a specific surface area of 300 m ² / g or more and / or a primary particle diameter of 1 to 10 nm with a media stirring type wet pulverizer; A step of preparing a slurry having a predetermined concentration by mixing at least a binder and a dispersion medium with the obtained powder, and a step of supplying the slurry to a spray dryer and spray-drying to obtain a granulated powder. Method for producing crystalline nanodiamond granulated powder (2) The average particle size of the granulated powder is 100 nm or more (1) Production method (3) Single crystal nanodiamond fine particles are in a state of lack of oxygen (1) The method for producing a granulated powder according to (2), characterized in that it is synthesized by a detonation method in (4) Metal oxide having an average particle diameter of 100 nm or more in the dispersed slurry A method for producing a granulated powder according to any one of (1) to (3), characterized by containing particles (5) obtained by the method according to any one of (1) to (4) Related to granulated powder.

The granulated powder of the present invention can provide a composite resin composition having a high refractive index and excellent light resistance, weather resistance, durability and the like.

The present invention will be described in detail below.
The present invention includes a step of pulverizing a cluster-like single crystal nanodiamond aggregate having a specific surface area of 300 m ² / g or more and / or a primary particle diameter of 1 to 10 nm with a media stirring type wet pulverizer, A step of preparing a slurry having a predetermined concentration by mixing at least a binder and a dispersion medium with the obtained powder, and supplying the slurry to a spray dryer and spray drying to produce a single crystal nano diamond granulated powder It is.

The method for synthesizing a cluster-like single crystal nanodiamond aggregate having a specific surface area of 300 m ² / g or more and / or a primary particle diameter of 1 to 10 nm used in the present invention is not particularly limited, and is conventionally known at high temperature and high pressure. Various production methods such as a method, an impact compression method, and a detonation method are included. In particular, the detonation method is preferable for efficiently collecting single crystal nanodiamond fine particles having a specific surface area of 300 m ² / g or more and / or a primary particle diameter of 1 to 10 nm.

As a method for producing single-crystal nanodiamond fine particles by the detonation method, there is a method in which an explosive component by using explosive energy of an explosive having a negative oxygen balance is directly used as a carbon source.

The explosive component described above is preferably a nitro compound containing three or more nitro groups, nitroamine, and nitrate esters. Specific examples include TNT (trinitrotoluene), tetril (tetranitromethylaniline), RDX (trimethylenetrinitroamine). ), HMX (tetramethylenetetranitroamine), PETN (pentaerythritol tetranitrate), and the like. These may be used alone or in combination of two or more. Of course, other industrial explosives can be used as long as they can provide the explosive impact pressure necessary for producing diamond. These explosive compositions can be produced by melting explosive components in a melting tank using water or oil such as glycerin as a heat medium, and solidifying by cooling.

Single-crystal nanodiamond fine particles by the detonation method are easily synthesized by detonating the explosive composition obtained by the method described in the preceding paragraph in a closed explosion container such as an explosion chamber having an appropriate size and strength. be able to. The explosion product is generally recovered as a water slurry by pre-filling water in a closed explosion container or by washing the container with water after the explosion. The recovered water slurry is allowed to stand to precipitate and separate the explosion product. Then, in order to remove metals and amorphous carbon mixed in the explosion product, acid treatment, which is a normal diamond refining method, is performed and washed with water. ,dry.

Single crystal nanodiamond fine particles obtained by the detonation method have a specific surface area of 300 m ² / g or more and / or a primary particle diameter of 1 nm to 30 nm, preferably 1 to 10 nm.

The single crystal nanodiamond fine particles obtained by the above-described method are usually aggregated in a cluster shape of about several hundred nm to several μm. These cluster-like single crystal nanodiamond aggregates are prepared by preparing a slurry with a dispersion medium, and then pulverizing the aggregated particles to the primary particle size by using a known media agitation type pulverizer such as a ball mill, a sand mill, or a bead mill. Can do.

The kind of the dispersion medium of the present invention is not particularly limited, and any of a water-soluble solvent, a water-insoluble solvent, a polar solvent, and a non-polar solvent can be used. Specifically, known solvents such as water, alcohol, ketone, ether, aromatic solvent, DMF, DMSO and the like are included.

The slurry in the present invention contains a binder in addition to the pulverized powder and dispersion medium. If the binder in this invention is a component melt | dissolved in a dispersion medium, there will be no restriction | limiting in particular, A thermoplastic resin, a thermosetting resin, a photocurable resin etc. will be mentioned.

The thermoplastic resins include high density polyethylene resin, low density polyethylene resin, linear low density polyethylene resin, ultra low density polyethylene resin, polypropylene resin, polybutadiene resin, cyclic olefin resin, polymethylpentene resin, polystyrene resin, ethylene acetate Vinyl copolymer, ionomer resin, ethylene vinyl alcohol copolymer resin, ethylene ethyl acrylate copolymer, acrylonitrile / styrene resin, acrylonitrile / chlorinated polystyrene / styrene copolymer resin, acrylonitrile / acrylic rubber / styrene copolymer resin, acrylonitrile / butadiene・ Styrene copolymer resin, acrylonitrile, EPDM, styrene copolymer resin, silicone rubber, acrylonitrile, styrene copolymer resin, cellulose, acetate, Rate resin, cellulose acetate resin, methacrylic resin, ethylene / methyl methacrylate copolymer resin, ethylene / ethyl acrylate resin, vinyl chloride resin, chlorinated polyethylene resin, polytetrafluoroethylene resin, tetrafluoroethylene / hexafluoropropylene copolymer Resin, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin, tetrafluoroethylene / ethylene copolymer resin, polytrifluorinated ethylene chloride resin, polyvinylidene fluoride resin, nylon 4,6, nylon 6, nylon 6,6 , Nylon 6,10, nylon 6,12, nylon 12, nylon 6, T, nylon 9, T, aromatic nylon resin, polyacetal resin, ultrahigh molecular weight polyethylene resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyethylene Lenna phthalate resin, polyvinyl alcohol resin, polyvinyl formal resin, polyvinyl acetal resin, polyvinyl butyral resin, HEIME copolyester resin, polycarbonate resin, modified polyphenylene ether resin, thermoplastic polyurethane elastomer, polyphenylene sulfide resin, polyether ether ketone resin, Liquid crystal polymer, polytetrafluoroethylene resin, polyfluoroalkoxy resin, polyetherimide resin, polysulfone resin, polyketone resin, thermoplastic polyimide resin, polyamideimide resin, polyarylate resin, polysulfone resin, polyethersulfone resin, biodegradable resin And biomass resins, but are not limited thereto. Also, a mixture of two or more of these resins may be used.

The thermosetting resin is not particularly limited as long as it is a compound having a functional group curable by heat, and examples thereof include a curable compound having a cyclic ether such as an epoxy group or an oxetanyl group. The photocurable resin is not particularly limited as long as it is a compound having a functional group that can be cured by light irradiation. For example, a vinyl group, vinyl ether group, allyl group, maleimide group, (meth) acryl group, etc. Examples thereof include resins having a curable compound having a saturated double bond.

It does not specifically limit as a thermosetting resin which has the said cyclic ether, For example, an epoxy compound, an alicyclic epoxy compound, an oxetane compound, a furan compound etc. are mentioned. Especially, an epoxy compound, an alicyclic epoxy compound, and an oxetane compound are suitable from a viewpoint of reaction rate or versatility. The epoxy compound is not particularly limited, and examples thereof include novolak-type epoxy compounds such as phenol novolak type, cresol novolak type, biphenyl novolak type, trisphenol novolak type, dicyclopentadiene novolak type; bisphenol A type, bisphenol F type, 2 Bisphenol type epoxy compounds such as 2,2'-diallyl bisphenol A type, hydrogenated bisphenol type, and polyoxypropylene bisphenol A type. Other examples include glycidylamine.

As a commercially available product of the above epoxy compound, for example, as a phenol novolak type epoxy compound, Epicron N-740, N-770, N-775 (all are manufactured by DIC Corporation), Epicoat 152, Epicoat 154 (and above) , All of which are manufactured by Japan Epoxy Resin Co., Ltd.). Examples of the cresol novolak type include epiclone N-660, N-665, N-670, N-673, N-680, N-695, N-665-EXP, N-672-EXP (all of which are DIC). As a biphenyl novolak type, for example, NC-3000P (manufactured by Nippon Kayaku Co., Ltd.); As a trisphenol novolak type, for example, EP1032S50, EP1032H60 (all of which are Japan Epoxy Resin Co., Ltd.) As a dicyclopentadiene novolak type, for example, XD-1000-L (manufactured by Nippon Kayaku Co., Ltd.), HP-7200 (manufactured by DIC Corporation); 828, Epicoat 834, Epicoat 1001, Epicoat 1004 (above, Izu , Japan Epoxy Resin Co., Ltd.), Epicron 850, Epicron 860, Epicron 4055 (all of which are manufactured by DIC Corporation); as commercial products of bisphenol F type epoxy compounds, for example, Epicoat 807 (Japan Epoxy Resin ( ), Epicron 830 (manufactured by DIC Corporation); 2,2′-diallylbisphenol A type, for example, RE-810NM (manufactured by Nippon Kayaku Co., Ltd.); ST-5080 (manufactured by Tohto Kasei Co., Ltd.); Examples of polyoxypropylene bisphenol A type include EP-4000 and EP-4005 (all of which are manufactured by Asahi Denka Kogyo Co., Ltd.).

Examples of commercially available oxetane compounds include etanacol EHO, etanacol OXBP, etanacol OXTP, etanacol OXMA (all of which are manufactured by Ube Industries, Ltd.). Moreover, it does not specifically limit as said alicyclic epoxy compound, For example, Celoxide 2021, Celoxide 2080, Celoxide 3000 (all are the Daicel UCB Co., Ltd. product) etc. are mentioned. These curable compounds having a cyclic ether group may be used alone or in combination of two or more.

The photocurable resin having an unsaturated double bond is not particularly limited, and examples thereof include resins having a vinyl group, a vinyl ether group, an allyl group, a maleimide group, a (meth) acryl group, and the like. From the viewpoint of versatility, a resin having a (meth) acryl group is preferred. In addition, in this specification, a (meth) acryl group means an acryl group or a methacryl group.

Examples of the resin having a (meth) acryl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 1,4-butanediol mono (meth) acrylate, carbitol (meth) acrylate, and acryloyl. Half-ester, polyethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, which is a reaction product of morpholine, hydroxyl group-containing (meth) acrylate and acid anhydride of polycarboxylic acid compound , Di (meth) acrylate of ε-caprolactone adduct of trimethylolpropane polyethoxytri (meth) acrylate, glycerin polypropoxytri (meth) acrylate, and neopentyl glycol hydroxypivalate (For example, KAYARAD HX-220, HX-620, etc., manufactured by Nippon Kayaku Co., Ltd.), pentaerythritol tetra (meth) acrylate, poly (meth) acrylate, dipentaerythritol and ε-caprolactone reaction product, dipenta Examples include erythritol poly (meth) acrylate, epoxy (meth) acrylate that is a reaction product of a mono- or polyglycidyl compound and (meth) acrylic acid, and the like.

There is no restriction | limiting in particular as a glycidyl compound used for the epoxy (meth) acrylate which is a reaction material of a mono- or polyglycidyl compound and (meth) acrylic acid, For example, bisphenol A, bisphenol F, bisphenol S, 4,4'- Biphenylphenol, tetramethylbisphenol A, dimethylbisphenol A, tetramethylbisphenol F, dimethylbisphenol F, tetramethylbisphenol S, dimethylbisphenol S, tetramethyl-4,4′-biphenol, dimethyl-4,4′-biphenylphenol, 1- (4-hydroxyphenyl) -2- [4- (1,1-bis- (4-hydroxyphenyl) ethyl) phenyl] propane, 2,2′-methylene-bis (4-methyl-6-tert- Butylphenol 4,4′-butylidene-bis (3-methyl-6-tert-butylphenol), trishydroxyphenylmethane, resorcinol, hydroquinone, pyrogallol, phenols having a diisopropylidene skeleton, 1,1-di-4-hydroxy Phenols having a fluorene skeleton such as phenylfluorene, phenolized polybutadiene, brominated bisphenol A, brominated bisphenol F, brominated bisphenol S, brominated phenol novolac, brominated cresol novolac, chlorinated bisphenol S, chlorinated bisphenol A, etc. And glycidyl etherified products of polyphenols.

Epoxy (meth) acrylate, which is a reaction product of these mono- or polyglycidyl compounds and (meth) acrylic acid, can be obtained by esterifying the epoxy group with an equivalent amount of (meth) acrylic acid. This synthesis reaction can be performed by a generally known method. For example, resorcin diglycidyl ether with an equivalent amount of (meth) acrylic acid, a catalyst (eg, benzyldimethylamine, triethylamine, benzyltrimethylammonium chloride, triphenylphosphine, triphenylstibine, etc.) and a polymerization inhibitor (eg, methoquinone) , Hydroquinone, methylhydroquinone, phenothiazine, dibutylhydroxytoluene and the like) and, for example, an esterification reaction is performed at 80 to 110 ° C. The (meth) acrylated resorcin diglycidyl ether thus obtained is a resin having a radically polymerizable (meth) acryloyl group.

If necessary, a photoreaction initiator or a thermosetting agent can be added to the slurry in the present invention. The photoinitiator is not particularly limited as long as it is for polymerizing an unsaturated double bond or an epoxy group in the curable resin by light irradiation. For example, a cationic polymerization type photoinitiator or a radical is used. A polymerization type photoinitiator is mentioned. The thermosetting agent is not particularly limited as long as it is for reacting and crosslinking the unsaturated double bond or epoxy group in the curable resin by heat. For example, acid anhydride, amines, phenol Imidazoles, dihydrazines, Lewis acids, Bronsted acid salts, polymercaptons, isocyanates, blocked isocyanates and the like.

Metal oxide fine particles can be added to the slurry of the present invention as a core material during granulation. The metal oxide fine particles used as the core material are not particularly limited, but silica, alumina, magnesium oxide and the like are preferable from the viewpoint of dispersion stability in the slurry. The average particle diameter of these metal oxide fine particles is preferably 100 nm or more.

If necessary, other additives can be added to the slurry in the present invention. For example, natural waxes, synthetic waxes and plasticizers such as metal salts of long chain aliphatic acids, release agents such as acid amides, esters and paraffins, stress relaxation agents such as nitrile rubber and butadiene rubber, trioxide Inorganic flame retardants such as antimony, antimony pentoxide, tin oxide, tin hydroxide, molybdenum oxide, zinc borate, barium metaborate, red phosphorus, aluminum hydroxide, magnesium hydroxide, calcium aluminate, tetrabromobisphenol A, anhydrous tetrabromo Brominated flame retardants such as phthalic acid, hexabromobenzene, brominated phenol novolak, silane coupling agents, titanate coupling agents, coupling agents such as aluminum coupling agents, aluminum hydroxide, calcium carbonate, barium sulfate , Magnesia, silicon nitride, boron nitride, ferai Or rare earth cobalt, metal powder such as gold, silver, nickel, copper, lead, iron powder, iron oxide, sand iron, etc., and inorganic filler or conductive particles such as graphite, carbon, petal, chrome, conductive particles, dyes and pigments Colorant such as carbon fiber, glass fiber, boron fiber, silicon carbide fiber, alumina fiber, silica-alumina fiber, etc., inorganic fiber, aramid fiber, polyester fiber, cellulose fiber, organic fiber such as carbon fiber, oxidation stable An agent, a light stabilizer, a moisture resistance improver, a thixotropy imparting agent, a diluent, an antifoaming agent, other various resins, a tackifier, an antistatic agent, a lubricant, an ultraviolet absorber, and the like can be blended.

The amount of the binder component used in the present invention is not particularly limited and is appropriately set depending on the application, but the content of the single crystal nanodiamond fine particles contained in the slurry is in the total components excluding the dispersion medium. The amount is preferably 1 to 98% by weight, and more preferably 5 to 95% by weight. More preferably, it is 10 to 90% by weight. If the content of the single crystal nanodiamond fine particles is less than 1% by weight, characteristics such as an increase in refractive index may not be imparted. On the other hand, if it is larger than 98% by weight, the bonding force between the fine particles becomes brittle, and the flexibility and toughness as the granulated powder are insufficient.

The slurry is supplied to a spray dryer by a pump or the like and spray-dried to obtain a granulated powder. The component concentration of the slurry is not particularly limited, but is preferably 0.01 to 10% by weight, more preferably 0.07 to 5% by weight, and still more preferably 0.1 to 3% by weight from the viewpoint of operation. is there. Here, if the component concentration is less than 0.01% by weight, the product yield decreases, which is not preferable. On the other hand, when the component concentration exceeds 10% by weight, the viscosity of the mixed aqueous solution increases, and it becomes difficult to obtain particles having a uniform particle size.

As the spray dryer, known ones (disk rotating type, nozzle type, etc.) can be used. The spray drying is performed by spraying the slurry into a hot air stream using a known method. At this time, as for the temperature of the hot air, the inlet temperature is desirably 100 to 200 ° C, preferably 150 to 180 ° C, and the outlet temperature is preferably 40 to 100 ° C. Here, when the inlet temperature is less than 100 ° C., the solid content is insufficiently dried, and when it exceeds 200 ° C., it is not economical. Further, if the outlet temperature is less than 40 ° C., the degree of drying of the powder is poor and adheres to the inside of the apparatus, which is not preferable.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
Example 1
Single crystal nanodiamond fine particles obtained by detonation and having the following elemental composition were used.
Carbon atom: 85.53% Hydrogen atom: 1.37%
Nitrogen atom: 1.83% Oxygen atom: 10.77%
Ash content: 0.5%

30 g of the above-mentioned single crystal nanodiamond fine particles were added to 600 ml of distilled water, and a dispersion test was conducted using a circulation type bead milling device (Ultra Apex Mill UAM-015, manufactured by Kotobuki Industries Co., Ltd.). Zirconia beads having an average particle size of 30 μm were used as the crushing beads, and the crushing beads were filled up to 70% of the crushing vessel volume. Crushing is performed at a flow rate of 150 ml / min. And the peripheral speed is 8 m / s. The crushing time was set under the condition that the solution passed through the crushing container 20 times.

The obtained dispersion was centrifuged for 60 minutes at a rotational speed of 6000 rpm using a high-speed cooling centrifuge (Himac CR22G, manufactured by Hitachi Koki Co., Ltd.).

The dispersion after the centrifugation is diluted with distilled water so that the single crystal nanodiamond fine particle concentration is 2.82% by weight, subjected to ultrasonic irradiation for 10 minutes using an ultrasonic homogenizer with 400 W output, and then subjected to dynamic light. As a result of measuring the particle size distribution using a scattering method particle size distribution analyzer (Nanotrack particle size analyzer UPA-EX, manufactured by Nikkiso Co., Ltd.), the average particle size was 11.9 nm.

100 g of the obtained dispersion was spray-dried using a two-fluid nozzle spray dryer (Mini Spray Dryer B-290, manufactured by Nihon Buch Co., Ltd.) to obtain a spherical single crystal diamond granule. The drying conditions of the spray dryer were an inlet temperature of 180 ° C., an outlet temperature of 71 ° C., aspirator suction of 100%, a supply flow rate of 10 ml / min, and a nitrogen gas flow rate of 35 ml / min.

Example 2
2.82 g of fine spherical silica as a core material: average particle diameter of 1 μm (Quatron SP-1B, manufactured by Fuso Chemical Industries, Ltd.) was added to 100 g of the dispersion. The slurry was subjected to a core material dispersion treatment using an ultrasonic cleaner (W-113MK2, manufactured by Honda Electronics Co., Ltd.) under conditions of an oscillation frequency of 24 KHz and an output of 110 W. The dispersion was spray-dried under the same conditions as in Example 1 to obtain a spherical granule in which single crystal nanodiamond fine particles were supported on finely divided spherical silica.

Example 3
Using 1-propanol as a solvent under the crushing conditions of Example 1, a dispersion having a single crystal nanodiamond fine particle concentration of 2.44 wt% and an average particle size of 3.4 nm was obtained. To 100 g of this dispersion, 9.76 g of a polyvinyl acetal resin (ESREC K, manufactured by Sekisui Chemical Co., Ltd.) was added as a binder. The obtained dispersion was spray-dried under the same conditions as in Example 1 to obtain a spherical granule containing a binder.

The single crystal nanodiamond granule in the example obtained by the above-described method was observed with a field emission electron microscope (JEM-2200FS, manufactured by JEOL Ltd.).

The granulated powder of the present invention can provide a high refractive index resin composition having high refractive index and excellent light resistance, weather resistance, durability and the like.

Claims (5)

A step of pulverizing a cluster-like single crystal nanodiamond aggregate having a specific surface area of 300 m ² / g or more and / or a primary particle diameter of 1 to 10 nm with a media stirring type wet pulverizer, and the pulverized powder And a step of preparing a slurry having a predetermined concentration by mixing at least a binder and a dispersion medium, and a step of supplying the slurry to a spray dryer and spray-drying to obtain a granulated powder. A method for producing granulated powder. The production method according to claim 1, wherein the granulated powder has an average particle size of 100 nm or more. 3. The method for producing a granulated powder according to claim 1, wherein the single crystal nanodiamond fine particles are synthesized by a detonation method in the absence of oxygen. The method for producing a granulated powder according to any one of claims 1 to 3, wherein the dispersed slurry contains metal oxide particles having an average particle diameter of 100 nm or more. A granulated powder obtained by the method according to any one of claims 1 to 4.