WO2017141689A1 - Liquide de dispersion de nanodiamant et son procédé de production - Google Patents

Liquide de dispersion de nanodiamant et son procédé de production Download PDF

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WO2017141689A1
WO2017141689A1 PCT/JP2017/003320 JP2017003320W WO2017141689A1 WO 2017141689 A1 WO2017141689 A1 WO 2017141689A1 JP 2017003320 W JP2017003320 W JP 2017003320W WO 2017141689 A1 WO2017141689 A1 WO 2017141689A1
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nanodiamond
compound
dispersion
dispersion liquid
weight
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PCT/JP2017/003320
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English (en)
Japanese (ja)
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木本訓弘
山本由紀
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株式会社ダイセル
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Priority to JP2018500017A priority Critical patent/JP6902015B2/ja
Publication of WO2017141689A1 publication Critical patent/WO2017141689A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C19/00—Other disintegrating devices or methods
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/25—Diamond
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K3/00—Materials not provided for elsewhere
    • C09K3/14—Anti-slip materials; Abrasives

Definitions

  • the present invention relates to a method for producing a nanodiamond dispersion including a step of eluting and removing a metal component mixed in by pulverization using a pulverizer such as a bead mill.
  • a pulverizer such as a bead mill.
  • nanodiamonds In recent years, development of fine-grained diamond materials called nanodiamonds has been underway. For nanodiamonds, so-called single-digit nanodiamonds having a particle diameter of 10 nm or less may be required depending on applications. Techniques relating to such nanodiamond dispersions are described, for example, in Patent Document 1 and Patent Document 2 below.
  • the nanodiamond having a primary particle size of 10 nm or less exhibits high mechanical strength, high thermal conductivity, high refractive index, and the like.
  • fine particles such as nanodiamonds have a large proportion of surface atoms (particularly surface atoms that are coordinately unsaturated)
  • the sum of van der Waals forces that can act between surface atoms of adjacent particles is large. And is prone to aggregation.
  • a phenomenon called agglutination can occur, in which coulomb interaction between crystal planes of adjacent crystallites contributes and is very tightly assembled.
  • nanodiamond has such a unique property that crystallites or primary particles can interact in a superimposed manner as described above, the primary particles are highly dispersed in, for example, a solvent by dissociating the primary particles of nanodiamond. Creating a state is very difficult.
  • Nanodiamonds take the form of aggregates (secondary particles) in which primary particles are assembled by very strong interaction at the stage of being generated by detonation, for example.
  • a crushing process using a pulverizer such as a bead mill is often employed.
  • the bead mill is a machine for crushing and / or crushing using metal beads, and zirconia beads are mainly used as the metal beads.
  • a mill container having an inner wall coated with zirconia is used.
  • nanodiamonds are crushed using such a bead mill, it is a metal that is very difficult to separate and remove because it has a particle size of several tens of nm or less, which is derived from metal beads or a mill container. It was inevitable that the fine powder was mixed in the nanodiamond, and the problem was that the purity of the nanodiamond decreased due to the mixing of the metal fine powder.
  • an object of the present invention is to achieve a single-digit nanometer with a high purity, in which the amount of metal components mixed is extremely low, through a process of easily and efficiently removing metal fine powder of several tens of nm or less mixed in nanodiamonds by crushing treatment.
  • the object is to provide a method for producing a diamond dispersion.
  • the present inventors have found that the metal component mixed by subjecting the nanodiamond to the crushing process using a pulverizer is subjected to heat treatment of the nanodiamond mixed with the metal component together with sulfuric acid.
  • the metal component can be eluted in sulfuric acid, and the metal component can be efficiently removed from the nanodiamond by separating and removing the sulfuric acid eluted from the metal component. Since the nano-diamond from which the slag has been removed has already been crushed, it can be easily re-dispersed by mixing with a dispersion medium, even if it is agglomerated by the sulfuric acid treatment. It was found that a dispersion was obtained. The present invention has been completed based on these findings.
  • the present invention is a nanodiamond dispersion having a particle diameter D50 (median diameter) of 10 nm or less through the following steps, and the total content of Zr compound, Al compound, Y compound, Fe compound, and Hf compound
  • a method for producing a nanodiamond dispersion in which a nanodiamond dispersion having a Zr, Al, Y, Fe, and Hf element conversion (weight) of 50 ppm or less of nanodiamond (weight) contained in the dispersion is obtained.
  • Step 1 Nano diamond is subjected to crushing treatment using a pulverizer
  • Step 2 A mixture of nano diamond and sulfuric acid after crushing treatment is subjected to heat treatment
  • Step 3 Sulfate radicals are removed from the mixture after the heat treatment
  • the present invention also provides the method for producing the nanodiamond dispersion liquid, wherein the nanodiamond subjected to step 1 is a detonation nanodiamond.
  • the present invention is also a dispersion of nanodiamond, wherein the nanodiamond in the dispersion has a particle diameter D50 (median diameter) of 10 nm or less, a Zr compound, an Al compound, a Y compound, an Fe compound, and an Hf compound.
  • a nanodiamond dispersion liquid in which the total content (converted to Zr, Al, Y, Fe, Hf elements; weight) is 50 ppm or less of the nanodiamond (weight) in the dispersion liquid is provided.
  • the present invention relates to the following.
  • the manufacturing method of the nano diamond dispersion liquid which obtains the nano diamond dispersion liquid which is 50 ppm or less of the nano diamond (weight) contained in a dispersion liquid.
  • Step 1 Nano diamond is subjected to pulverization using a pulverizer
  • Step 2 A mixture of nano diamond and sulfuric acid after pulverization is subjected to heat treatment
  • Step 3 Sulfate radicals are removed from the mixture after the heat treatment
  • the nanodiamond subjected to the crushing treatment is a nanodiamond dispersion having a pH of 8 or more (preferably 8 to 12, particularly preferably 9 to 11, more preferably 9.5 to 11.5).
  • a method for producing a diamond dispersion is
  • the neutralization treatment is a treatment in which a basic substance or an aqueous solution thereof is added until the pH of the nanodiamond dispersion becomes 12 or more to precipitate a sulfate radical as a salt, according to [12] or [13].
  • a method for producing a nanodiamond dispersion liquid is a treatment of repeatedly washing with water until the pH of the nanodiamond dispersion becomes 6 or more.
  • the neutralization treatment is a treatment in which a basic substance or an aqueous solution thereof is added until the pH of the nanodiamond dispersion becomes 12 or more to precipitate a sulfate radical as a salt, according to [12] or [13].
  • a dispersion of nanodiamond, the particle diameter D50 (median diameter) of nanodiamond in the dispersion being 10 nm or less, and the total content of Zr compound, Al compound, Y compound, Fe compound, and Hf compound A nanodiamond dispersion in which the amount (Zr, Al, Y, Fe, Hf element conversion; weight) is 50 ppm or less of the nanodiamond (weight) in the dispersion.
  • the nanodiamond dispersion according to [15] wherein the nanodiamond in the nanodiamond dispersion has a zeta potential at pH 8 to 12 of ⁇ 60 to ⁇ 20 mV.
  • the nanodiamond dispersion liquid according to [15] or [16], wherein the dispersion medium for dispersing nanodiamond is water or an aqueous dispersion medium containing 50% by weight or more of water.
  • the Zr compound, the Al compound, the Y compound, the Fe compound, and the Hf compound each include a single metal.
  • the manufacturing method of the nanodiamond dispersion liquid of the present invention has the above-described configuration, the metal component is efficiently removed by a simple method, the amount of the metal component mixed is extremely low, and the nanodiamond dispersion liquid having excellent dispersibility, That is, a single-digit nanodiamond dispersion can be produced.
  • Nanodiamond has high mechanical strength, electrical insulation, excellent thermal conductivity, deodorizing effect, and antibacterial effect
  • the nanodiamond dispersion obtained by the production method of the present invention has the above characteristics. Since the nanodiamond is contained in a highly dispersed state, the above characteristics can be highly expressed. Therefore, it is suitably used as an abrasive, a conductivity imparting material, an insulating material, a deodorant, an antibacterial agent and the like.
  • the method for producing a nanodiamond dispersion of the present invention is a nanodiamond dispersion having a particle diameter D50 (median diameter) of 10 nm or less through the following steps: a Zr compound, an Al compound, a Y compound, an Fe compound, and Hf
  • a nanodiamond dispersion liquid in which the total content of compounds (in terms of Zr, Al, Y, Fe, Hf elements; weight) is 50 ppm or less of the nanodiamond (weight) contained in the dispersion liquid is obtained.
  • Step 1 Nano diamond is subjected to a crushing process using a pulverizer (hereinafter referred to as “crushing process step”).
  • Step 2 The mixture of nano diamond and sulfuric acid after the crushing treatment is subjected to a heat treatment (hereinafter, sometimes referred to as “sulfuric acid treatment step”).
  • Step 3 Remove sulfate radicals from the mixture after the heat treatment (hereinafter referred to as “sulfate radical removal step”).
  • step 1 (cracking treatment step) is produced, for example, through the following production step and purification step (including an acid treatment step, an oxidation treatment step, a pre-cracking treatment step, etc.).
  • Nanodiamonds can be produced, for example, by detonation.
  • the detonation method includes an air-cooled detonation method and a water-cooled detonation method.
  • the air-cooled detonation method is particularly preferable in that nanodiamonds having smaller primary particles can be obtained than the water-cooled detonation method.
  • the detonation may be performed in an air atmosphere, or may be performed in an inert gas atmosphere such as a nitrogen atmosphere or an argon atmosphere.
  • the nanodiamond to be subjected to the crushing treatment in the above step 1 is preferably detonation nanodiamond, that is, nanodiamond produced by detonation, and more preferably air-cooled detonation nanodiamond, that is, air-cooled detonation. Is a nanodiamond produced by
  • a molded explosive with an electric detonator is installed inside a pressure-resistant container for detonation.
  • a metal container such as iron is used.
  • the volume of the container is, for example, 0.5 to 40 m 3 , preferably 2 to 30 m 3 .
  • RDX cyclotrimethylenetrinitroamine
  • TNT / RDX The weight ratio of TNT to RDX is, for example, in the range of 40/60 to 60/40.
  • the electric detonator is then detonated and the explosive is detonated in the container.
  • Detonation refers to an explosion associated with a chemical reaction in which the reaction flame surface moves at a speed exceeding the speed of sound.
  • crude nanodiamonds are generated by the action of the pressure and energy of the shock wave generated by the explosion, using carbon that is liberated due to partial incomplete combustion of the explosive used.
  • the crude nanodiamond obtained through the production process contains metal oxides such as Al, Fe, Co, Cr and Ni contained in the vessel used for the production reaction (for example, Fe 2 O 3 , Fe 3 O 4). , Co 2 O 3 , Co 3 O 4 , NiO, Ni 2 O 3, etc.) are included as metallic impurities, and the metallic impurities cause nano diamond adhesion.
  • by-products such as graphite may be included, and this graphite is derived from carbon that did not form nanodiamond crystals among the carbon released by partial incomplete combustion of the explosive used. This also causes nano diamond adhesion.
  • the purification process is a process for removing these impurities.
  • the acid treatment step is a step of removing the metallic impurities mixed in the crude nanodiamond obtained through the generation step, and an acid is added to the crude nanodiamond dispersion obtained by dispersing the crude nanodiamond in water.
  • the metal impurities are eluted by addition to the acid, and then the acid from which the metal impurities are eluted is separated and removed to remove the metal impurities.
  • a mineral acid is preferable, and examples thereof include hydrochloric acid, hydrofluoric acid, sulfuric acid, nitric acid, aqua regia and the like. These can be used individually by 1 type or in combination of 2 or more types.
  • the concentration of the acid used for the acid treatment is, for example, 1 to 50% by weight.
  • the acid treatment temperature is, for example, 70 to 150 ° C.
  • the acid treatment time is, for example, 0.1 to 24 hours.
  • the acid treatment can be performed under reduced pressure, normal pressure, or increased pressure.
  • decantation it is preferable to wash the solids (including nanodiamonds) with water, and it is particularly preferable to repeat the water washing until the pH of the precipitation solution reaches 2 to 3, for example.
  • the oxidation treatment step is a step of removing graphite (graphite) mixed in the crude nanodiamond obtained through the generation step, and a crude nanodiamond dispersion liquid obtained by dispersing the crude nanodiamond in water (preferably, The graphite is removed by causing an oxidizing agent to act on the nanodiamond dispersion obtained through the acid treatment step.
  • the oxidizing agent include chromic acid, chromic anhydride, dichromic acid, permanganic acid, perchloric acid, and salts thereof. These can be used individually by 1 type or in combination of 2 or more types.
  • the concentration of the oxidizing agent used in the oxidation treatment is, for example, 3 to 50% by weight.
  • the amount of the oxidizing agent used in the oxidation treatment is, for example, 300 to 500 parts by weight with respect to 100 parts by weight of the rough nanodiamond subjected to the oxidation treatment.
  • the oxidation treatment temperature is, for example, 100 to 200 ° C.
  • the oxidation treatment time is, for example, 1 to 24 hours.
  • the oxidation treatment can be performed under reduced pressure, normal pressure, or increased pressure.
  • the oxidation treatment is preferably performed in the presence of an acid (particularly a mineral acid. Examples similar to the mineral acid used in the acid treatment step) can be performed from the viewpoint of improving the graphite removal efficiency.
  • the acid concentration is, for example, 5 to 80% by weight.
  • it is preferable to remove the supernatant for example, by decantation.
  • decantation it is preferable to wash the solid content (including the nanodiamond adherend) with water.
  • the supernatant liquid at the beginning of water washing is colored, it is preferable to repeat the water washing of the solid content until the supernatant liquid becomes transparent visually.
  • an alkali and hydrogen peroxide are reacted with the solution containing the nanodiamond adherend obtained through the oxidation treatment step.
  • the alkali include sodium hydroxide, ammonia, potassium hydroxide and the like.
  • the alkali concentration is preferably 0.1 to 10% by weight, more preferably 0.2 to 8% by weight, and still more preferably 0.5 to 5% by weight.
  • the concentration of hydrogen peroxide is preferably 1 to 15% by weight, more preferably 2 to 10% by weight, and still more preferably 4 to 8% by weight.
  • the temperature for carrying out the reaction is, for example, 40 to 95 ° C., and the reaction time is, for example, 0.5 to 5 hours.
  • the reaction can be performed under reduced pressure, normal pressure, or increased pressure. After the reaction, it is preferable to remove the supernatant by decantation.
  • the pH of the precipitate obtained by the above decantation it is preferable to adjust the pH of the precipitate obtained by the above decantation.
  • an acid for example, hydrochloric acid
  • the pH is adjusted to, for example, 2 to 3. Is preferred.
  • the pre-cracking treatment step next, it is preferable to perform water washing by a centrifugal sedimentation method on the solid content (including the nanodiamond adherend) in the precipitation liquid. More specifically, an operation for performing solid-liquid separation on the precipitate or suspension using a centrifuge, an operation for separating the precipitate from the supernatant, and then ultrapure water for the precipitate. It is preferable to carry out a series of processes including the operation of adding and suspending, for example, repeatedly. This washing with water is preferably carried out until the electrical conductivity per 1% by weight of the solid content of the dispersion becomes, for example, 20 ⁇ S / cm or less (preferably 15 ⁇ S / cm or less).
  • the dispersion after washing with water is preferably acidic, and its pH is, for example, in the range of 3.5 to 6.5, and preferably in the range of 4 to 6. Washing with water until the electrical conductivity value and pH value of the dispersion are within the above ranges is preferable in that it facilitates crushing of nanodiamonds (separation of primary particles from secondary particles) in the next step 1. .
  • the pH of the nanodiamond aggregate-containing dispersion is, for example, 8 or more (for example, 8 to 12), preferably 9 or more (for example, 9 to 11), more preferably 9.5 to 10.5.
  • the solid concentration (nanodiamond concentration) is preferably 2% by weight or more (for example, 2 to 15% by weight), more preferably 4% by weight from the viewpoint of obtaining a single-digit nanodiamond dispersion having a high concentration. % Or more (for example, 4 to 10% by weight).
  • Step 1 is, for example, a step of subjecting nanodiamond obtained by the above method (for example, nanodiamond in a nanodiamond aggregate-containing dispersion) to a pulverization process using a pulverizer.
  • nanodiamond obtained by the above method for example, nanodiamond in a nanodiamond aggregate-containing dispersion
  • pulverization process using a pulverizer.
  • detonation nanodiamonds take the form of aggregates (secondary particles) in which the primary particles are assembled with very strong interactions.
  • the primary particles of nanodiamond can be separated from the nanodiamond adherend (secondary particles) by subjecting to a crushing treatment.
  • the pulverizer examples include a bead mill, a ball mill, a jet mill, and an ultrasonic homogenizer.
  • a bead mill because nanodiamonds can be finely pulverized until, for example, the particle diameter D50 (median diameter) is 10 nm or less.
  • the bead mill is an apparatus having a configuration in which beads are filled in a mill container (or a crushing chamber) having a rotation shaft in the center. By rotating the rotation shaft, motion is given to the beads. The object is crushed by the strong shearing force generated by the movement.
  • the beads those of various materials (for example, zirconia, zirconia-silica ceramics, glass, alumina, steel, etc.) are known. Beads (zirconia beads) are preferably used. Further, as the bead mill, a mill vessel whose inner wall is coated with zirconia can be used.
  • the zirconia beads and zirconia coating are at least one selected from Zr compounds, Al compounds, Y compounds, Fe compounds, and Hf compounds (mainly ZrO 2 , Y 2 O 3 , Al 2 O 3 , HfO). 2 etc.) is included.
  • the zirconia-silica ceramic beads mainly contain ZrO 2 , Y 2 O 3 , SiO 2 , and Al 2 O 3 .
  • step 1 classification may be performed before applying to step 2 to remove coarse nanodiamond particles and the like.
  • the classification process can be performed using, for example, a centrifuge. By performing the classification treatment, a nanodiamond dispersion having a more uniform particle size distribution can be obtained.
  • the so-called zeta potential of the nanodiamond in the nanodiamond dispersion obtained through the above steps is preferably ⁇ 60 to ⁇ 20 mV, more preferably ⁇ 50 to ⁇ 30 mV.
  • the particle diameter D50 (median diameter) is, for example, 10 nm or less (preferably 8 nm or less, particularly preferably 6 nm or less).
  • Step 2 is a step of subjecting the mixture of nano-diamond and sulfuric acid after the crushing treatment obtained through Step 1 to a heat treatment.
  • Step 1 it is inevitable that a component derived from a pulverizer (a fine powder having a particle diameter D50 (median diameter) of, for example, 50 nm or less) is mixed into the nanodiamond by being subjected to a pulverization treatment using a pulverizer. .
  • a component derived from a pulverizer a fine powder having a particle diameter D50 (median diameter) of, for example, 50 nm or less
  • Total content of Zr compound, Al compound, Y compound, Fe compound, and Hf compound contained in nano diamond after pulverization treatment obtained through step 1 Is, for example, 3,000 ppm or more (for example, 3,000 to 15,000 ppm) of nanodiamond (weight). Therefore, in Steps 2 and 3, the components derived from the grinder mixed in Step 1 are removed.
  • the nanodiamond subjected to the sulfuric acid treatment step may be a nanodiamond dispersion or a nanodiamond dry powder.
  • the nanodiamond dispersion obtained through step 1 can be used as it is, and when the nanodiamond dry powder is subjected to this step, the nanodiamond dispersion is obtained through step 1.
  • the dried nanodiamond dispersion is subjected to a drying process (for example, spray drying using a spray dryer or evaporation to dryness using an evaporator) to prepare a dry powder and using it. Can do.
  • the sulfuric acid it is preferable to use one having a concentration of, for example, 50% by weight or more (preferably 55% by weight or more, particularly preferably 60% by weight or more).
  • the amount of sulfuric acid used is, for example, 2 volume times or more, preferably 10 volume times or more, particularly preferably 20 volume times or more of nanodiamond (solid content conversion). Use of sulfuric acid in the above range is preferable in that the components derived from the pulverizer can be efficiently removed.
  • the heat treatment temperature of the mixture of nanodiamond and sulfuric acid is, for example, 200 ° C. or higher (preferably 220 ° C. or higher, particularly preferably 240 ° C. or higher).
  • the heat treatment time is, for example, 5 minutes or longer (preferably 15 minutes or longer, particularly preferably 30 minutes or longer).
  • the heat treatment can be performed using, for example, a sand bath, a hot air dryer, a microwave reaction device, or the like.
  • the heat treatment can be performed under normal pressure or under pressure.
  • the components derived from the pulverizer are, for example, Zr compound, Al compound, Y compound, Fe compound, And at least one selected from Hf compounds (mainly ZrO 2 , Y 2 O 3 , Al 2 O 3 , HfO 2 ).
  • Hf compounds mainly ZrO 2 , Y 2 O 3 , Al 2 O 3 , HfO 2
  • components derived from the pulverizer are mainly ZrO 2 , Y 2 O 3 , SiO 2 , and Al 2 O 3 .
  • Step 3 is a step of removing sulfate radicals from the mixture after the sulfuric acid treatment. More specifically, in the sulfuric acid treatment in step 2, it is a step of separating and removing sulfate radicals produced by the dissolution of components derived from the pulverizer into sulfuric acid.
  • the sulfate radical includes unreacted sulfuric acid used in the sulfuric acid treatment step, sulfate ions, metal sulfate, and the like.
  • the method for separating and removing the sulfate radical is not particularly limited, and examples thereof include washing with water and neutralization. These can be performed singly or in combination of two or more.
  • a preferred example of the present invention is a method in which treatment is performed in the order of water washing, neutralization and water washing.
  • the solid content (including nanodiamonds) in the mixture after the sulfuric acid treatment is washed with water.
  • the water washing treatment is preferably performed while removing the supernatant by decantation or centrifugation, and the pH of the supernatant of the mixture after the sulfuric acid treatment is, for example, 6 or more (eg, 6 to 7), It is preferable to repeat the water washing process until it becomes 6.5 or more.
  • the neutralization treatment is performed by adding a basic substance or an aqueous solution thereof.
  • the sulfate radical can be precipitated as a salt by adding a basic substance or an aqueous solution thereof.
  • the basic substance include alkali metal compounds (for example, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; alkali metal carbonates such as sodium carbonate and potassium carbonate; alkali metal carbonates such as sodium bicarbonate).
  • alkali metal carboxylate such as sodium acetate and potassium acetate
  • sodium alkoxide such as sodium methoxide and sodium ethoxide
  • alkaline earth metal compound for example, alkaline earth such as magnesium hydroxide and calcium hydroxide
  • Metal hydroxides alkaline earth metal carbonates such as magnesium carbonate and calcium carbonate
  • alkaline earth metal carboxylates such as magnesium acetate and calcium acetate
  • alkaline earth metal alkoxides such as magnesium ethoxide, etc.
  • the basic substance or an aqueous solution thereof it is preferable to add the basic substance or an aqueous solution thereof to a dispersion obtained by dispersing the precipitate obtained through the water washing treatment in water until the pH of the dispersion becomes 12 or more.
  • the water washing treatment is preferably performed again, and the water washing treatment is preferably performed while removing the supernatant by decantation or centrifugation.
  • the precipitate (nanodiamond slurry) obtained through the water washing-neutralization-water washing treatment is excellent in redispersibility, and is mixed with a dispersion medium to disperse to primary particles as if dissolved.
  • the nanodiamond dispersion liquid preferably the primary particles of nanodiamond are dispersed as colloidal particles
  • nanodiamond particle diameter D50 (median diameter) is 10 nm or less (preferably 8 nm or less, particularly preferably 6 nm or less) A dispersion) is obtained.
  • particle diameter D50 is a value that can be measured by a so-called dynamic light scattering method.
  • the nano-diamond obtained by crushing using a bead mill using zirconia beads as a pulverizer or a bead mill equipped with a mill container with an inner wall coated with zirconia is mixed with components derived from the pulverizer.
  • the components derived from the pulverizer can be removed by performing the above steps 1 to 3.
  • the total content of Zr compound, Al compound, Y compound, Fe compound, and Hf compound in the nanodiamond dispersion obtained by mixing the precipitate obtained through the above steps 1 to 3 with a dispersion medium ( Zr, Al, Y, Fe, Hf element conversion; weight) is 50 ppm or less of nanodiamond (weight) contained in the dispersion, that is, according to the production method of the present invention, inclusion of components derived from a pulverizer A nanodiamond dispersion whose amount is below the detection limit is obtained.
  • the nanodiamond dispersion liquid of the present invention is a nanodiamond dispersion liquid, in which the nanodiamond particle diameter D50 (median diameter) in the dispersion liquid is 10 nm or less, and a Zr compound, Al compound, Y compound, Fe compound, And the total content of Hf compounds (in terms of Zr, Al, Y, Fe, Hf elements; weight) is, for example, 200 ppm or less (preferably 100 ppm or less, particularly preferably 50 ppm or less) of nanodiamond (weight) in the dispersion. .
  • the nanodiamond dispersion liquid of the present invention can be produced, for example, by the method for producing the nanodiamond dispersion liquid.
  • the nanodiamond contained in the nanodiamond dispersion is, for example, detonation nanodiamond (nanodiamond produced by detonation), preferably air-cooled detonation nanodiamond (nanodiamond produced by air-cooled detonation) ).
  • Air-cooled detonation nanodiamonds are preferred in that a nanodiamond dispersion having a smaller particle diameter D50 (median diameter) is obtained because primary particles tend to be smaller than water-cooled detonation nanodiamonds.
  • the dispersion medium contained in the nanodiamond dispersion liquid is a medium for appropriately dispersing nanodiamonds.
  • a solvent in which nanodiamonds can easily disperse examples thereof include water, methanol, ethanol, ethylene glycol, dimethyl sulfoxide, and N-methylpyrrolidone. These can be used alone or in combination of two or more.
  • the zeta potential of nanodiamond affects the dispersion stability of nanodiamond in the dispersion medium.
  • the zeta potential of the nanodiamond contained in the nanodiamond dispersion of the present invention at pH 8-12 is preferably ⁇ 60 to ⁇ 20 mV, more preferably ⁇ 50 to ⁇ 30 mV. Therefore, it is excellent in dispersibility and temporal dispersion stability.
  • the zeta potential of the nanodiamond contained in the nanodiamond dispersion is a value measured for nanodiamond in the nanodiamond dispersion having a nanodiamond concentration of 0.2% by weight at 25 ° C.
  • ultrapure water is used as the diluent.
  • the nanodiamond dispersion liquid of the present invention is a single-digit nanodiamond dispersion liquid with extremely low content of components derived from a pulverizer and excellent dispersion stability. Therefore, the characteristics of nanodiamond (high mechanical strength) , Electrical insulation, excellent thermal conductivity, deodorant effect, antibacterial effect), and can be suitably used as an abrasive, conductivity imparting material, insulating material, deodorant, antibacterial agent, etc. be able to.
  • the nanodiamond dispersion liquid of the present invention is added to a resin and used, the above-described excellent characteristics can be imparted to the resin by adding a small amount.
  • the pH was measured using a pH meter (trade name “Lacom Tester PH110” manufactured by Nikko Hansen Co., Ltd.).
  • Example 1 ⁇ Purification process> (Acid treatment process) 200 g of air-cooled detonation nano diamond cocoon (manufactured by Daicel Corporation) with a primary particle size of nano diamond of 4 to 6 nm was weighed, 2 L of 10 wt% hydrochloric acid aqueous solution was added, and heat-treated under reflux for 1 hour. Went. After cooling, it was washed with water until the pH of the precipitate became 2 by decantation, and the supernatant was removed as much as possible.
  • Acid treatment process 200 g of air-cooled detonation nano diamond cocoon (manufactured by Daicel Corporation) with a primary particle size of nano diamond of 4 to 6 nm was weighed, 2 L of 10 wt% hydrochloric acid aqueous solution was added, and heat-treated under reflux for 1 hour. Went. After cooling, it was washed with water until the pH of the precipitate became 2 by decantation, and the supernatant was removed as much as
  • pre-crushing treatment was performed. Specifically, first, 1 L of a 10 wt% aqueous sodium hydroxide solution and 1 L of a 30 wt% aqueous hydrogen peroxide solution are added to the precipitate obtained by decantation in the above-described oxidation treatment step to form a slurry. The slurry was heat-treated for 1 hour under reflux under normal pressure conditions. The heat treatment temperature was 50 to 105 ° C. After cooling, the supernatant was removed by decantation.
  • hydrochloric acid is added to the precipitate obtained by this decantation to adjust the pH of the precipitate to 2.5, and then the solid content (including the nanodiamond adherent) in this precipitate is centrifuged. Washed with water. Specifically, an operation for performing solid-liquid separation on the precipitate or suspension using a centrifuge, an operation for separating the precipitate from the supernatant, and then ultrapure water for the precipitate. A series of processes including the operation of adding and suspending was repeated until the electrical conductivity of the suspension reached 56 ⁇ S / cm when the solid content concentration (nanodiamond concentration) was adjusted to 6% by weight. It was. The pH of the solution after such washing with water was 4.3.
  • ⁇ Crushing process> Next, the crushing process was performed. Specifically, after adding a sodium hydroxide aqueous solution to 300 mL of the slurry (nanodiamond adherence-containing dispersion) obtained through the pre-crushing treatment step and adjusting the pH to 10, the beads mill dispersion was performed on the slurry. went.
  • the apparatus used was a bead mill RMB manufactured by Imex Corporation. After filling 300 mL of zirconia beads having a diameter of 0.03 mm as a crushing medium, 300 mL of slurry adjusted to pH 10 was added, and the peripheral speed was set to 8 m / s, and crushing was performed for 120 minutes.
  • ⁇ Classification process> The crushed liquid was collected, coarse particles were removed by classification operation by centrifugation, and a nanodiamond dispersion liquid was obtained.
  • the resulting nanodiamond dispersion has a solid content concentration of 5.8%, a particle diameter D50 (median diameter) of 4.3 nm, an electric conductivity of 680 ⁇ S / cm, a pH of 9.34, and the zeta potential of the nanodiamond is ⁇ It was 48 mV.
  • this nanodiamond dispersion was pulverized. Specifically, 100 mL of nanodiamond dispersion liquid was spray-dried. The apparatus used was a spray dryer type B-290 manufactured by Nippon Büch Corporation. This obtained nanodiamond powder (1). The metal component contained in the obtained nanodiamond powder (1) was subjected to ICP emission spectroscopic analysis. The results are shown in Table 1.
  • ⁇ Sulfuric acid treatment process 300 mg of nanodiamond powder (1) was weighed, and 10 mL of 64 wt% sulfuric acid was added thereto to obtain a mixture (1). The resulting mixture (1) was refluxed on a sand bath set at 250 ° C. 40 minutes.
  • the supernatant liquid was removed to obtain a black precipitate on which nanodiamonds had adhered.
  • the nanodiamond was dispersed so as to dissolve, and a nanodiamond dispersion (nanodiamond concentration: 1% by weight) was obtained.
  • the particle diameter D50 (median diameter) of the nanodiamond in the nanodiamond dispersion was 5.3 nm.
  • ICP emission spectroscopic analysis was performed on the metal component contained in the nanodiamond powder (2) obtained by evaporating and drying the water of the nanodiamond dispersion. The results are shown in Table 1.
  • the Zr element, Al element, Y element, Hf element, and Fe element content in the supernatant liquid (1) are all Zr element, Al element, Y element in the nanodiamond powder (1). Since the Zr element, Al element, Y element, Hf element, and Fe element were not detected from the nanodiamond powder (2), the above sulfuric acid The metal components (particularly, Zr compound, Al compound, Y compound, Hf compound, and Fe compound) derived from the bead mill using the zirconia beads contained in the nanodiamond powder (1) were removed by the treatment. I understood it.
  • nanodiamond content in the nanodiamond dispersion is determined by the precision balance of the weighed value of 3 to 5 g of the weighed dispersion and the dried product (powder) remaining after evaporation of water from the weighed dispersion by heating. Based on the weighed value, calculation was performed.
  • the particle diameter D50 (median diameter) of the nanodiamond contained in the nanodiamond dispersion is determined using a dynamic light scattering method (non-contact backscattering method) using an apparatus manufactured by Spectris (trade name “Zetasizer Nano ZS”). ).
  • Spectris trade name “Zetasizer Nano ZS”.
  • For the measurement sample use a nanodiamond dispersion obtained by diluting with ultrapure water so that the nanodiamond concentration is 0.5 to 2.0% by weight and then irradiating with an ultrasonic cleaner. did.
  • the zeta potential of the nanodiamond contained in the nanodiamond dispersion was measured by laser Doppler electrophoresis using an apparatus (trade name “Zetasizer Nano ZS”) manufactured by Spectris.
  • a nanodiamond dispersion obtained by diluting with ultrapure water so that the nanodiamond concentration was 0.2% by weight and then irradiating with an ultrasonic cleaner was used.
  • the pH of the nanodiamond dispersion subjected to the measurement was confirmed using a pH test paper (trade name “Three Band pH Test Paper”, manufactured by ASONE CORPORATION).
  • the method for producing a nanodiamond dispersion liquid of the present invention it is possible to easily and efficiently remove a metal component and produce a nanodiamond dispersion liquid having an extremely low mixing amount of the metal component and excellent dispersibility. it can.
  • the nanodiamond dispersion obtained by the production method of the present invention can highly express properties having high mechanical strength, electrical insulation, excellent thermal conductivity, deodorizing effect, antibacterial effect, It is suitably used as an abrasive, conductivity imparting material, insulating material, deodorant, antibacterial agent and the like.

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  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
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Abstract

L'invention concerne un procédé de production d'un liquide de dispersion de nanodiamant à un seul chiffre et de grande pureté ayant seulement une très faible quantité de constituants métalliques contaminants, par une étape consistant à éliminer de façon simple et efficace une fine poudre métallique mélangée avec le nanodiamant. Le procédé de production de liquide de dispersion de nanodiamant selon l'invention a pour objet d'obtenir un liquide de dispersion de nanodiamant ayant une granulométrie D50 (taille médiane) de 10 nm ou moins, et selon lequel la teneur totale d'un composé de Zr, d'un composé d'Al, d'un composé d'Y, d'un composé de Fe, et d'un composé d'Hf (en termes de Zr, Al, Y, Fe et Hf élémentaires ; poids) est de 50 ppm ou moins de nanodiamant contenu dans le liquide de dispersion (poids), par une étape 1 pour soumettre le nanodiamant à un traitement de pulvérisation au moyen d'un pulvérisateur, une étape 2 pour soumettre un mélange du nanodiamant après le traitement de pulvérisation et d'acide sulfurique à un traitement thermique, et une étape 3 d'élimination des radicaux sulfate du mélange après le traitement thermique.
PCT/JP2017/003320 2016-02-17 2017-01-31 Liquide de dispersion de nanodiamant et son procédé de production WO2017141689A1 (fr)

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