WO2016052067A1 - Method for producing nickel particles - Google Patents
Method for producing nickel particles Download PDFInfo
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- WO2016052067A1 WO2016052067A1 PCT/JP2015/075027 JP2015075027W WO2016052067A1 WO 2016052067 A1 WO2016052067 A1 WO 2016052067A1 JP 2015075027 W JP2015075027 W JP 2015075027W WO 2016052067 A1 WO2016052067 A1 WO 2016052067A1
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- nickel
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
- B22F1/102—Metallic powder coated with organic material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
- B22F1/105—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material containing inorganic lubricating or binding agents, e.g. metal salts
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
- B22F9/24—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2301/00—Metallic composition of the powder or its coating
- B22F2301/15—Nickel or cobalt
Definitions
- the present invention relates to a method for producing nickel particles that can be suitably used for applications such as a conductive paste for forming internal electrodes of a multilayer ceramic capacitor (MLCC).
- MLCC multilayer ceramic capacitor
- the metal fine particles have physical and chemical characteristics different from those of bulk metals, various materials such as electrode materials such as conductive pastes and transparent conductive films, high-density recording materials, catalyst materials, and ink-jet ink materials are used. It is used for industrial materials.
- electrode materials such as conductive pastes and transparent conductive films
- high-density recording materials such as conductive pastes and transparent conductive films
- catalyst materials such as conductive pastes and transparent conductive films
- ink-jet ink materials are used for industrial materials.
- fine metal particles have been made finer to about several tens to several hundreds of nanometers.
- the multilayer ceramic capacitor (MLCC) electrodes have been increasingly made into thin film multilayers.
- the material for the electrode layer is preferably nanoparticles having an average particle size as small as less than 150 nm, a uniform particle size, small variation, and excellent dispersibility as much as possible. It has been. Therefore, industrially, development of a technique for stably producing metal fine particles having a sharp particle size distribution is required.
- Patent Document 1 As a method for producing metal fine particles having a uniform particle shape and particle diameter and less secondary agglomeration, for example, in Patent Document 1, by adding a reducing agent to a solution of a metal salt, there has been proposed a multistage production method including a step of generating fine particles (nuclei) and a step of reducing and precipitating a metal from a solution of a metal salt in the presence of a reducing agent.
- Patent Document 2 As a multistage production method of metal fine particles including a core and a shell of different metals, for example, in Patent Document 2, a step of heating a mixture containing nickel particles, a cobalt salt and a primary amine to obtain a complexing reaction solution; There has been proposed a method for producing nickel-cobalt nanoparticles comprising heating the complexing reaction solution to obtain a nickel-cobalt nanoparticle slurry.
- Patent Document 1 since the size of the ultrafine metal particles serving as a nucleus exceeds 100 nm and the average particle diameter of the finally produced metal fine particles is about 1 ⁇ m, aggregation is unlikely to occur. The allowable range for variation in particle size is also wide. Therefore, the technique of Patent Document 1 is not applicable to the production of fine metal particles that are required for current industrial materials, for example, the average particle diameter is less than 150 nm.
- An object of the present invention is to stably produce metal fine particles having an average particle size as small as less than 150 nm, a uniform particle size, and small variations.
- the method for producing nickel particles of the present invention includes the following steps I to IV: I) A step of forming seed particles by mixing and heating a metal salt containing at least nickel carboxylate and an aliphatic primary monoamine. II) A step of preparing a nickel complex solution in which a nickel salt is dissolved in an organic amine by mixing and heating the nickel salt and an aliphatic primary monoamine, III) A step of mixing the seed particles and the nickel complex solution to obtain a mixed solution, IV) Step of forming nickel particles by heating and reducing nickel ions in the mixed solution, and depositing and growing nickel metal with the seed particles as nuclei, It is characterized by providing.
- the average particle diameter D1 of the seed particles may be in the range of 10 nm to 50 nm by observation with a scanning electron microscope, and the average particle diameter D2 of the nickel particles is 20 nm or more. It may be within a range of 150 nm or less, and 8 ⁇ D2 / D1.
- both the variation coefficient CV1 of the seed particle diameter and the variation coefficient CV2 of the nickel particle diameter may be 0.2 or less, and the ratio (CV1 / CV2). ) May be within the range of 0.7 to 1.3.
- the aliphatic primary monoamine used in Step II may have a carbon number in the range of 6 or more and 20 or less.
- the metal salt may include nickel carboxylate and one or more metal salts selected from copper, silver, gold, platinum and palladium.
- the heating in the step I and the step IV may be performed by microwaves.
- nickel particles having a small average particle size of, for example, less than 150 nm, a sharp particle size distribution, and a small CV value can be stably produced. can do.
- the nickel particles can be suitably used as an electronic material such as a conductive paste for forming an internal electrode of a multilayer ceramic capacitor (MLCC).
- MLCC multilayer ceramic capacitor
- FIG. 2 is a scanning electron micrograph of nickel particles (seed particles) produced in Example 1.
- FIG. 2 is a scanning electron micrograph of nickel particles produced in Example 1.
- FIG. 2 is a scanning electron micrograph of nickel particles produced in Example 1.
- the nickel particle manufacturing method according to the present embodiment includes steps I to IV.
- Step I seed particles are formed by mixing and heating a metal salt containing at least nickel carboxylate and an aliphatic primary monoamine.
- the seed particles function as nuclei for the growth of nickel particles in Step IV.
- nickel carboxylate used in step I for example, nickel formate, nickel acetate or the like having a relatively low dissociation temperature (decomposition temperature) in the reduction process is preferably used.
- the nickel carboxylate may be an anhydride or a hydrate.
- inorganic salts such as nickel chloride, nickel nitrate, nickel sulfate, nickel carbonate, nickel hydroxide instead of nickel carboxylate, but in the case of inorganic salts, dissociation (decomposition) is high temperature. In the reduction process, heating at a high temperature is necessary, which is not preferable.
- nickel salts composed of organic ligands such as Ni (acac) 2 ( ⁇ -diketonato complex) and stearate ions, but using these nickel salts increases the cost of raw materials. It is not preferable.
- the metal salt used in Step I may contain, for example, one or more metal salts selected from copper, silver, gold, platinum and palladium in addition to nickel carboxylate.
- these metal salts for example, carboxylates such as copper formate and palladium acetate, nitrates such as silver nitrate, and chlorides such as chloroauric acid and chloroplatinic acid are preferably used.
- the metal salt may be an anhydride or a hydrate.
- it is preferable to use a copper salt and it is most preferable to use copper formate having a relatively low decomposition temperature.
- Step I by adding a metal salt other than nickel carboxylate, the formation of seed particles can be promoted, and the particle diameter of the seed particles can be easily controlled.
- the blending ratio with the metal salt is preferably as follows, for example.
- the ratio of nickel carboxylate to copper salt is determined from the viewpoint of oxidation stability of nickel and copper alloy seed particles produced in step I and nickel particles produced in step IV.
- the ratio of the copper element to the element is preferably in the range of 3 wt% to 50 wt%.
- the ratio of nickel carboxylate to metal salt is, for example, from the viewpoint of product failure such as short-circuit due to migration by a dissimilar metal other than nickel such as silver and a decrease in capacitance.
- the ratio of the metal element other than the copper salt to the nickel element is preferably in the range of 0.01 wt% to 2 wt%.
- the aliphatic primary monoamine is not particularly limited as long as it can form a complex with nickel ions, and can be solid or liquid at room temperature.
- room temperature means 20 ° C. ⁇ 15 ° C.
- the aliphatic primary monoamine that is liquid at room temperature also functions as an organic solvent for forming the nickel complex.
- secondary amines have great steric hindrance, which may hinder the good formation of nickel complexes, and tertiary amines do not have the ability to reduce nickel ions, so none can be used.
- diamines are not preferred because of the high stability of complexes formed with nickel ions, among metal ions, and the reduction temperature is high, so that the reactivity is very low and the resulting nickel particles are easily distorted.
- the aliphatic primary monoamine can control the particle size of the seed particles produced by adjusting the length of its carbon chain, for example.
- the aliphatic primary monoamine is preferably selected from those having about 6 to 20 carbon atoms. The larger the carbon number, the smaller the particle size of the seed particles obtained.
- examples of such amines include octylamine, trioctylamine, dioctylamine, hexadecylamine, dodecylamine, tetradecylamine, stearylamine, oleylamine, myristylamine, and laurylamine.
- the aliphatic primary monoamine functions as a surface modifier during the production of seed particles, secondary aggregation can be suppressed even after the removal of the aliphatic primary monoamine.
- the aliphatic primary monoamine is also preferable from the viewpoint of ease of processing operation in the washing step of separating the solid component of the seed particles generated after the reduction reaction from the solvent or the unreacted aliphatic primary monoamine.
- the aliphatic primary monoamine is preferably one having a boiling point higher than the reduction temperature from the viewpoint of ease of reaction control when the nickel complex is reduced to obtain seed particles. That is, the aliphatic primary monoamine has a boiling point of preferably 180 ° C. or higher, more preferably 200 ° C. or higher.
- the aliphatic primary monoamine preferably has 9 or more carbon atoms.
- the boiling point of C 9 H 21 N (nonylamine), which is an aliphatic primary monoamine having 9 carbon atoms is 201 ° C.
- the aliphatic primary monoamine is liquid at room temperature from the viewpoint of ease of processing operation in the washing step of separating the solid component of the seed particles produced after the reduction reaction and the solvent or the unreacted aliphatic primary monoamine. Is preferred. Furthermore, the aliphatic primary monoamine is preferably one having a boiling point higher than the reduction temperature from the viewpoint of easy control of reaction when reducing the nickel complex to obtain seed particles.
- the amount of the aliphatic primary monoamine is preferably 2 mol or more, more preferably 2.2 mol or more with respect to 1 mol of the metal ion. When the amount of the aliphatic primary monoamine is less than 2 mol, it is difficult to control the particle diameter of the obtained nickel particles, and the particle diameter is likely to vary.
- the upper limit of the amount of the aliphatic primary monoamine is not particularly limited.
- the amount is preferably 20 mol or less, more preferably 4 mol or less with respect to 1 mol of the metal ion. That is, the amount of the aliphatic primary monoamine is preferably in the range of 2 to 20 mol, more preferably in the range of 2 to 4 mol, and most preferably in the range of 2.2 to 4 mol with respect to 1 mol of the metal ion.
- Organic solvent ⁇ Organic solvent>
- an organic solvent different from the aliphatic primary monoamine is used in Step I. You may add newly.
- the organic solvent that can be used is not particularly limited as long as it does not inhibit complex formation between an aliphatic primary monoamine and a metal ion such as nickel ion.
- an ether-based organic solvent having 4 to 30 carbon atoms A saturated or unsaturated hydrocarbon organic solvent having 7 to 30 carbon atoms, an alcohol organic solvent having 8 to 18 carbon atoms, or the like can be used.
- an organic solvent having a boiling point of 170 ° C. or higher more preferably in the range of 200 to 300 ° C. It is better to choose one.
- Specific examples of such an organic solvent include tetraethylene glycol, n-octyl ether, polyalphaolefin having a carbon number in the range of 20 to 40, and the like.
- the heating method for forming seed particles is not particularly limited, and for example, heating by a heat medium such as an oil bath or heating by microwave irradiation may be used. Heating is preferred. Heating by microwave irradiation enables uniform heating and energy can be directly applied to metal ions, so that rapid heating can be performed. As a result, the entire reaction solution can be made uniform at a desired temperature, and reduction of metal ions, formation of nuclei, and growth occur simultaneously in the entire solution. As a result, monodisperse seed particles having a narrow particle size distribution can be shortened. It can be manufactured easily in time.
- the use wavelength of the microwave is not particularly limited and is, for example, 2.45 GHz.
- the heating temperature for forming the seed particles is preferably 170 ° C. or higher, more preferably 180 ° C. or higher, from the viewpoint of suppressing variation in the shape of the obtained seed particles.
- the upper limit of the heating temperature is not particularly limited, but is preferably set to 270 ° C. or less, for example, from the viewpoint of efficiently performing the treatment.
- Step I the slurry of seed particles obtained by heating is coated with an aliphatic primary monoamine by, for example, static separation, removing the supernatant, washing with an appropriate solvent, and drying. Seed particles are obtained.
- the average particle diameter D1 of the seed particles obtained in the step I by observation with a scanning electron microscope is, for example, preferably 50 nm or less, more preferably in the range of 10 nm to 50 nm.
- the average particle diameter D1 of the seed particles is less than 10 nm, the handling property is lowered and the particles are easily aggregated.
- the average particle diameter D1 of the seed particles exceeds 50 nm, the dispersion of the particle diameter at the seed particle stage becomes large, and when used as a nucleating agent, nickel particles having a sharp particle diameter distribution are stable. Manufacturing becomes difficult.
- the nickel particles obtained in Step I have a particle diameter variation coefficient (CV1) of preferably 0.2 or less, and more preferably 0.15 or less. When the CV value exceeds 0.2, the variation in the particle diameter of the nickel particles obtained in the later step IV may increase.
- CV1 particle diameter variation coefficient
- Step II a nickel salt solution and an aliphatic primary monoamine are mixed and heated to prepare a nickel complex solution in which the nickel salt is dissolved in an organic amine.
- the type of nickel salt is not particularly limited.
- nickel hydroxide, nickel chloride, nickel nitrate, nickel sulfate, nickel carbonate, nickel carboxylate, Ni (acac) 2 ( ⁇ -diketonato complex), nickel stearate nickel chloride or nickel carboxylate is preferable, and it is advantageous to use nickel carboxylate having a relatively low dissociation temperature (decomposition temperature) in the reduction process.
- the nickel carboxylate may be used alone or in combination with other nickel salts.
- the same thing as the process I can be used for nickel carboxylate.
- Step II the same aliphatic primary monoamine as in Step I can be used.
- Nickel complex solution The nickel concentration in the nickel complex solution is, for example, preferably in the range of 2 to 13% by weight, and more preferably in the range of 6 to 12% by weight.
- a multi-step reaction that distinguishes Step I for forming seed particles and Step IV for growing nickel particles from the seed particles, and compared with a one-step synthesis method, The concentration of nickel can be increased and productivity can be improved.
- the one-step synthesis method when the nickel concentration exceeds 10% by weight, the reactivity is lowered and the particle size is difficult to control.
- Divalent nickel ions are known as ligand-substituted active species, and the ligand of the complex to be formed may change complex formation easily by ligand exchange depending on temperature and concentration.
- the carboxylate ion is bidentate or monodentate.
- the carboxylate ion is bidentate or monodentate.
- the amine concentration is excessively large, there is a possibility that a carboxylate ion is present in the outer sphere.
- the aliphatic primary monoamine In order to obtain a uniform solution at the intended reaction temperature (reduction temperature), at least one of the ligands must be coordinated with an aliphatic primary monoamine. In order to take this state, it is necessary that the aliphatic primary monoamine is excessively present in the reaction solution, and it is preferable that at least 2 mol per 1 mol of nickel ions is present, and 2.2 mol or more exist. More preferably.
- the upper limit of the amount of the aliphatic primary monoamine is not particularly limited. For example, from the viewpoint of productivity, the amount is preferably 20 mol or less, more preferably 4 mol or less with respect to 1 mol of nickel ions.
- the amount of the aliphatic primary monoamine is preferably in the range of 2 to 20 mol, more preferably in the range of 2 to 4 mol, and most preferably in the range of 2.2 to 4 mol with respect to 1 mol of nickel ions.
- the complex formation reaction can proceed even at room temperature, it is preferable to perform heating at a temperature of 100 ° C. or higher in order to carry out the reaction reliably and more efficiently.
- This heating is particularly advantageous when a nickel carboxylate hydrate such as nickel acetate tetrahydrate is used as the nickel carboxylate.
- the heating temperature is preferably a temperature exceeding 100 ° C., more preferably a temperature of 105 ° C. or more, so that the ligand substitution reaction between the coordinated water coordinated with nickel carboxylate and the aliphatic primary monoamine is performed. It is done efficiently.
- water molecules as complex ligands can be dissociated and the water can be discharged out of the system, so that complexes can be formed efficiently.
- nickel acetate tetrahydrate has a complex structure in which two coordinated water, two acetate ions that are bidentate ligands, and two water molecules exist in the outer sphere at room temperature.
- the water molecule as the complex ligand can be dissociated by heating at a temperature higher than 100 ° C. preferable.
- the heating temperature is preferably 175 ° C. or lower from the viewpoint of reliably separating from the subsequent reduction process and completing the complex formation reaction.
- the heating temperature in Step II is preferably in the range of 105 ° C. to 175 ° C., more preferably in the range of 125 to 160 ° C.
- the heating time can be appropriately determined according to the heating temperature and the content of each raw material, but is preferably 15 minutes or more from the viewpoint of reliably completing the complex formation reaction. Although there is no upper limit on the heating time, heating for a long time is useless from the viewpoint of saving energy consumption and process time.
- the heating method is not particularly limited, and for example, heating by a heat medium such as an oil bath or heating by microwave irradiation may be used, but heating by microwave irradiation is preferable. Heating by microwave irradiation enables uniform heating in the mixed solution, and energy can be directly applied to nickel ions, so that rapid heating can be performed.
- the use wavelength of the microwave is not particularly limited and is, for example, 2.45 GHz.
- the complex formation reaction between nickel carboxylate and aliphatic primary monoamine can be confirmed by a change in the color of the solution when a solution obtained by mixing nickel carboxylate and aliphatic primary monoamine is heated.
- this complex formation reaction is carried out by measuring the absorption maximum wavelength of the absorption spectrum observed in the wavelength region of 300 nm to 750 nm using, for example, an ultraviolet / visible absorption spectrum measuring apparatus, and measuring the maximum absorption wavelength of the raw material (for example, nickel acetate). It can be confirmed by observing the shift of the complexing reaction solution with respect to tetrahydrate.
- Step III This step is a step in which the seed particles obtained in Step I and the nickel complex solution obtained in Step II are mixed to obtain a mixed solution.
- Step III seed particles or a slurry containing seed particles may be added to the nickel complex solution, or a nickel complex solution may be added to the slurry containing seed particles.
- the nickel complex mixed in step III is not used for the formation of new nuclei, but is used for the growth from seed particles to nickel particles in the next step IV. That is, as long as the concentration of the nickel complex in the mixed solution does not exceed the critical concentration for nucleation, the nickel complex is used only for particle growth. Therefore, the amount of the nickel complex for obtaining nickel particles having the target particle size in Step IV can be calculated based on the particle size of the seed particles.
- the nickel concentration in the nickel complex in the mixed solution can be calculated by, for example, the following formula (1).
- nickel particles having an average particle size in the range of 20 to 150 nm are obtained using seed particles having an average particle size in the range of 10 to 50 nm and a coefficient of variation of the particle size of 0.2 or less
- the nickel concentration in the nickel complex in the liquid is preferably in the range of 4 to 13% by weight, for example, and more preferably in the range of 6 to 12% by weight.
- D2 D1 (1 + Y / X) 1/3 (1)
- D2 is the average particle size (unit; nm) of the nickel particles
- D1 is the average particle size (unit: nm) of the seed particles
- Y is the nickel complex in the mixed solution
- X is the amount of nickel in the seed particles (unit: g).
- Step IV In the step IV, nickel ions in the mixed liquid obtained in the step III are heated and reduced, and nickel particles are formed by depositing and growing nickel metal with the seed particles as nuclei.
- the heating method in Step IV is not particularly limited, and for example, heating by a heat medium such as an oil bath or heating by microwave irradiation may be used, but heating by microwave irradiation is preferable. Heating of the nickel complex by microwave irradiation enables uniform heating of the nickel complex and energy can be directly applied to the nickel complex, so that rapid heating can be performed. As a result, the entire reaction solution can be made uniform at a desired temperature, and the reduction and growth of the nickel complex (or nickel ions) can occur simultaneously in the entire solution, resulting in monodisperse nickel particles having a narrow particle size distribution. It can be easily manufactured in a short time.
- the use wavelength of the microwave is not particularly limited and is, for example, 2.45 GHz.
- the heating temperature in Step IV is preferably 170 ° C. or higher, more preferably 180 ° C. or higher, from the viewpoint of suppressing variation in the shape of the nickel particles obtained.
- the heating temperature in step IV is too low, the reduction reaction rate from the nickel complex to nickel (zero valence) tends to be slow, and the growth of metallic nickel covering the seed particles tends to be slow.
- the upper limit of the heating temperature is not particularly limited, but is preferably set to 270 ° C. or less, for example, from the viewpoint of efficiently performing the treatment. Moreover, when it exceeds 270 degreeC, since carbonization reaction will advance and it will become easy to produce
- step IV the slurry of nickel particles obtained by wet heat reduction is, for example, statically separated, the supernatant liquid is removed, washed with an appropriate solvent, and dried to obtain aliphatic 1 Nickel particles coated with quaternary monoamine are obtained.
- step III and step IV It is possible to repeat part of the above step III and step IV a plurality of times. That is, after performing Step IV, a nickel complex solution may be further added, and Step IV may be performed again. Also in this case, the nickel complex added later is not used for the formation of new nuclei, but is used for the growth from seed particles to nickel particles. In other words, even when part of Step III and Step IV are repeated, the concentration of the nickel complex will not exceed the critical concentration for nucleation unless the rate of addition of the nickel complex into the mixture exceeds the rate consumed for particle growth. The added nickel complex is only used for particle growth because it does not exceed. Therefore, the amount of the nickel complex for obtaining the target particle size can be calculated based on the particle size of the seed particles.
- the nickel particles obtained in step IV are various shapes such as spherical, pseudospherical, oblong, cubic, truncated tetrahedral, dihedral pyramid, octahedral, icosahedral, icosahedral, etc.
- spherical or pseudospherical is preferable, and spherical is more preferable.
- the shape of the nickel particles can be confirmed by observing with a scanning electron microscope (SEM), for example.
- the average particle diameter D2 of the nickel particles obtained in Step IV is preferably 150 nm or less, and more preferably 100 nm or less. More specifically, the average particle diameter of the nickel particles is preferably in the range of 20 to 150 nm, more preferably in the range of 20 to 100 nm.
- the relationship between the average particle diameter D1 of the seed particles obtained in step I and the average particle diameter D2 of the nickel particles obtained in step IV is, for example, 8 ⁇ D2 / D1 from the viewpoint of keeping the particle size distribution of the nickel particles sharp. It is preferable that On the other hand, when 8 ⁇ D2 / D1, the particle size distribution of the nickel particles becomes broad, and aggregated particles are gradually generated, which may result in poor dispersibility.
- the nickel particles obtained in Step IV have a particle diameter variation coefficient (CV2) of preferably 0.2 or less, more preferably 0.15 or less.
- CV2 particle diameter variation coefficient
- the relationship between the variation coefficient CV1 of the seed particle diameter and the variation coefficient CV2 of the nickel particle diameter is such that the ratio (CV1 / CV2) is within a range of 0.7 to 1.3. preferable.
- CV1 / CV2 is less than 0.7, seed particles are aggregated, or nickel particles become coarse due to non-uniform or local heating. Variation in growth rate may increase.
- the reason why it is possible to control the particle diameter with high accuracy compared to the conventional one-step synthesis method is not clear, but it is reasonable to consider it as follows. Is possible.
- the environmental factors of the reaction system for example, the concentration of the reaction solution, stirring conditions, moisture, and the natural rate affecting the reaction rate
- the presence of trace amounts of impurities and trace metals derived from raw materials greatly affects the growth of nickel particles, making it difficult to control the particle size.
- the seed particles to be generated have a small particle size in the step I where the influence of environmental factors of the reaction system is likely to occur, the variation in the particle size is suppressed accordingly. Can do.
- Step IV where nickel particles are grown, seed particles have a greater influence on nickel particle growth than environmental factors in the reaction system. It is thought that it can be controlled with high accuracy.
- nickel particles having a small average particle size of, for example, less than 150 nm, a sharp particle size distribution, and a small CV value can be stably produced.
- the nickel particles can be suitably used as an electronic material such as a conductive paste for forming an internal electrode of a multilayer ceramic capacitor (MLCC).
- MLCC multilayer ceramic capacitor
- Step I Preparation of first nickel particles> Add 2.45 g of copper formate tetrahydrate and 21.9 g of nickel formate dihydrate to 331 g of oleylamine, and dissolve copper formate and nickel formate in oleylamine by heating at 120 ° C for 20 minutes under nitrogen flow. did.
- Nickel particles (1-B) were prepared by drying for a period of time.
- FIG. 1 An SEM photograph of nickel particles (1-B) is shown in FIG. Referring to FIG. 1, the average particle diameter of nickel particles (1-B) was 17 nm, and the CV value was 0.13.
- Step II Preparation of nickel complex solution> A nickel complex solution was prepared by adding 2611 g of nickel acetate tetrahydrate to 6949 g of oleylamine and heating at 140 ° C. for 4 hours under a nitrogen flow.
- Steps III to IV Preparation of mixed solution and preparation of nickel particles>
- 337 g of the nickel particle slurry (1-A) is added, stirred, heated to 225 ° C. by microwave irradiation, and maintained at that temperature for 15 minutes to maintain the nickel particle slurry (1- C) was prepared.
- the resulting nickel particle slurry (1-C) was allowed to stand and separated, the supernatant was removed, washed twice with toluene and methanol, and then dried in a vacuum dryer maintained at 60 ° C. for 6 hours.
- nickel particles (1-D) were prepared.
- FIG. 2 An SEM photograph of nickel particles (1-D) is shown in FIG. Referring to FIG. 2, the nickel particles (1-D) had an average particle diameter of 80 nm and a CV value of 0.13.
- Example 2 ⁇ Step I: Preparation of first nickel particles> Copper formate and nickel formate were dissolved in oleylamine in the same manner as in Example 1 except that the amount of copper formate tetrahydrate used in Example 1 was changed to 0.61 g.
- Step II Preparation of nickel complex solution> A nickel complex solution was prepared in the same manner as in Example 1 by adding 882 g of nickel acetate tetrahydrate to 1977 g of dodecylamine.
- Steps III to IV Preparation of mixed solution and preparation of nickel particles>
- 333 g of nickel particle slurry (2-A) was added to obtain nickel particle slurry (2-C) in the same manner as in Example 1, washed with toluene and methanol, and then dried.
- nickel particles (2-D) were prepared. From the results of the SEM photograph, the average particle diameter of the nickel particles (2-D) was 141 nm, and the CV value was 0.14.
- Example 3 ⁇ Step I: Preparation of first nickel particles>
- 314 g of dodecylamine was used, and the amounts of copper formate tetrahydrate and nickel formate dihydrate were changed to 0.49 g and 43.8 g, respectively. Except for this, copper formate and nickel formate were dissolved in dodecylamine in the same manner as in Example 1.
- Example 2 In the same manner as in Example 1, 342 g of nickel particle slurry (3-A) was obtained, washed with toluene and methanol, and dried to prepare nickel particles (3-B). From the results of the SEM photograph, the average particle diameter of the nickel particles (3-B) was 20 nm, and the CV value was 0.11.
- Step II Preparation of nickel complex solution> A nickel complex solution was prepared in the same manner as in Example 1 by adding 1797 g of nickel acetate tetrahydrate to 4028 g of dodecylamine.
- Steps III to IV Preparation of mixed solution and preparation of nickel particles>
- 332 g of nickel particle slurry (3-A) was added to obtain nickel particle slurry (3-C) in the same manner as in Example 1, washed with toluene and methanol, and then dried.
- nickel particles (3-D) were prepared. From the result of the SEM photograph, the average particle diameter of the nickel particles (3-D) was 63 nm, and the CV value was 0.10.
- Example 4 ⁇ Step I: Preparation of first nickel particles> 297 g of octylamine was used instead of 331 g of oleylamine in Example 1, and the amounts of copper formate tetrahydrate and nickel formate dihydrate were changed to 0.98 g and 65.7 g, respectively. Except for the above, copper formate and nickel formate were dissolved in octylamine in the same manner as in Example 1.
- Nitamiconductor 347g of nickel particle slurry (4-A) was prepared by irradiating the above solution with microwaves and heating to 170 ° C and maintaining the temperature for 5 minutes.
- the obtained nickel particle slurry (4-A) was treated in the same manner as in Example 1 to prepare nickel particles (4-B). From the results of the SEM photograph, the average particle diameter of the nickel particles (4-B) was 15 nm, and the CV value was 0.12.
- Step II Preparation of nickel complex solution> A nickel complex solution was prepared by adding 636 g of nickel acetate tetrahydrate to 1050 g of octylamine and heating at 120 ° C. for 4 hours under a nitrogen flow.
- Steps III to IV Preparation of mixed solution and preparation of nickel particles>
- 337 g of the nickel particle slurry (4-A) is added, stirred, heated to 170 ° C. by irradiation with microwaves, and the temperature is maintained for 60 minutes to maintain the nickel particle slurry (4- C) was prepared.
- the obtained nickel particle slurry (4-C) was treated in the same manner as in Example 1 to prepare nickel particles (4-D). From the result of the SEM photograph, the average particle diameter of the nickel particles (4-D) was 30 nm, and the CV value was 0.13.
- Example 5 ⁇ Step I: Preparation of first nickel particles> Nickel formate was dissolved in oleylamine in the same manner as in Example 1 except that the copper formate tetrahydrate in Example 1 was not used.
- the solution was irradiated with microwaves and heated to 190 ° C. to prepare 345 g of nickel particle slurry (5-A).
- the obtained nickel particle slurry (5-A) was treated in the same manner as in Example 1 to prepare nickel particles (5-B). From the results of the SEM photograph, the average particle diameter of the nickel particles (5-B) was 30 nm, and the CV value was 0.14.
- Step II Preparation of nickel complex solution> A nickel complex solution was prepared by adding 1526 g of nickel acetate tetrahydrate to 1918 g of octylamine and heating at 120 ° C. for 4 hours under a nitrogen flow.
- Steps III to IV Preparation of mixed solution and preparation of nickel particles>
- 335 g of nickel particle slurry (5-A) is added, and after stirring, heated to 170 ° C. by irradiation with microwaves and maintained at that temperature for 60 minutes to maintain the nickel particle slurry (5- C) was prepared.
- the obtained nickel particle slurry (5-C) was treated in the same manner as in Example 1 to prepare nickel particles (5-D). From the results of the SEM photograph, the average particle diameter of the nickel particles (5-D) was 112 nm, and the CV value was 0.15.
- Example 6 Preparation of first nickel particles> Palladium acetate and nickel formate were dissolved in oleylamine in the same manner as in Example 1 except that 0.036 g of palladium acetate was used instead of 2.45 g of copper formate tetrahydrate in Example 1.
- Example 2 In the same manner as in Example 1, 344 g of nickel particle slurry (6-A) was obtained, and nickel particles (6-B) were prepared. From the result of the SEM photograph, the average particle diameter of the nickel particles (6-B) was 45 nm, and the CV value was 0.13.
- Step II Preparation of nickel complex solution> A nickel complex solution was prepared by adding 543 g of nickel acetate tetrahydrate to 1216 g of oleylamine and heating at 140 ° C. for 4 hours under a nitrogen flow.
- Steps III to IV Preparation of mixed solution and preparation of nickel particles> 334 g of nickel particle slurry (6-A) was added to the above nickel complex solution, and nickel particle slurry (6-C) was prepared in the same manner as in Example 1. The obtained nickel particle slurry (6-C) was treated in the same manner as in Example 1 to prepare nickel particles (6-D). From the result of the SEM photograph, the average particle diameter of the nickel particles (6-D) was 120 nm, and the CV value was 0.13.
- Step II Preparation of nickel complex solution> A nickel complex solution was prepared by adding 2670 g of nickel acetate tetrahydrate to 5092 g of dodecylamine and heating at 140 ° C. for 4 hours under a nitrogen flow.
- Steps III to IV Preparation of mixed solution and preparation of nickel particles>
- 336 g of nickel particle slurry (7-A) was added, and nickel particle slurry (7-C) was prepared in the same manner as in Example 1.
- the obtained nickel particle slurry (7-C) was treated in the same manner as in Example 1 to prepare nickel particles (7-D). From the result of the SEM photograph, the average particle diameter of the nickel particles (7-D) was 85 nm, and the CV value was 0.11.
- Step II Preparation of nickel complex solution> A nickel complex solution was prepared by adding 1653 g of nickel acetate tetrahydrate to 2730 g of octylamine and heating at 120 ° C. for 4 hours under a nitrogen flow.
- Steps III to IV Preparation of mixed solution and preparation of nickel particles>
- 338 g of the nickel particle slurry (8-A) was added, stirred, heated to 170 ° C. by microwave irradiation, and maintained at that temperature for 60 minutes to maintain the nickel particle slurry (8- C) was prepared.
- the obtained nickel particle slurry (8-C) was treated in the same manner as in Example 1 to prepare nickel particles (8-D). From the result of the SEM photograph, the average particle diameter of the nickel particles (8-D) was 92 nm, and the CV value was 0.15.
- Example 9 Preparation of first nickel particles> In the same manner as in Example 8, nickel acetate was dissolved in dodecylamine.
- Steps III to IV Preparation of mixed solution and preparation of nickel particles>
- 338 g of nickel particle slurry (9-A) was added, and in the same manner as in Example 8, a nickel particle slurry (9-C) was prepared.
- the obtained nickel particle slurry (9-C) was treated in the same manner as in Example 8 to prepare nickel particles (9-D). From the result of the SEM photograph, the average particle diameter of the nickel particles (9-D) was 41 nm, and the CV value was 0.13.
- Step I Preparation of first nickel particles> To 287 g of octylamine were added 0.29 g of palladium acetate and 89.1 g of nickel acetate tetrahydrate, and the mixture was heated at 120 ° C. for 20 minutes under a nitrogen flow to dissolve palladium acetate and nickel acetate in octylamine.
- the above solution was irradiated with microwaves and heated to 170 ° C., and the temperature was maintained for 5 minutes to prepare 347 g of nickel particle slurry (10-A).
- the obtained nickel particle slurry (10-A) was treated in the same manner as in Example 1 to prepare nickel particles (10-B). From the result of the SEM photograph, the average particle diameter of the nickel particles (10-B) was 19 nm, and the CV value was 0.16.
- Step II Preparation of nickel complex solution> A nickel complex solution was prepared by adding 954 g of nickel acetate tetrahydrate to 1819 g of octylamine and heating at 120 ° C. for 4 hours under a nitrogen flow.
- Steps III to IV Preparation of mixed solution and preparation of nickel particles>
- 337 g of nickel particle slurry (10-A) was added, stirred, heated to 170 ° C. by microwave irradiation, and held at that temperature for 60 minutes to maintain the nickel particle slurry (10-A).
- C) was prepared.
- the obtained nickel particle slurry (10-C) was treated in the same manner as in Example 1 to prepare nickel particles (10-D). From the result of the SEM photograph, the average particle diameter of the nickel particles (10-D) was 77 nm, and the CV value was 0.14.
Abstract
Description
I)少なくともカルボン酸ニッケルを含む金属塩と、脂肪族1級モノアミンと、を混合し、加熱することによって種粒子を形成する工程、
II)ニッケル塩と、脂肪族1級モノアミンと、を混合し、加熱することによって、ニッケル塩を有機アミンに溶解させたニッケル錯体溶液を準備する工程、
III)前記種粒子と前記ニッケル錯体溶液とを混合して混合液を得る工程、
IV)前記混合液中のニッケルイオンを加熱還元し、前記種粒子を核として金属ニッケルを析出・成長させてニッケル粒子を形成する工程、
を備えることを特徴とする。 The method for producing nickel particles of the present invention includes the following steps I to IV:
I) A step of forming seed particles by mixing and heating a metal salt containing at least nickel carboxylate and an aliphatic primary monoamine.
II) A step of preparing a nickel complex solution in which a nickel salt is dissolved in an organic amine by mixing and heating the nickel salt and an aliphatic primary monoamine,
III) A step of mixing the seed particles and the nickel complex solution to obtain a mixed solution,
IV) Step of forming nickel particles by heating and reducing nickel ions in the mixed solution, and depositing and growing nickel metal with the seed particles as nuclei,
It is characterized by providing.
工程Iでは、少なくともカルボン酸ニッケルを含む金属塩と、脂肪族1級モノアミンと、を混合し、加熱することによって種粒子を形成する。種粒子は、工程IVにおいて、ニッケル粒子の成長の核として機能するものである。 [Step I]
In Step I, seed particles are formed by mixing and heating a metal salt containing at least nickel carboxylate and an aliphatic primary monoamine. The seed particles function as nuclei for the growth of nickel particles in Step IV.
工程Iで用いるカルボン酸ニッケルとしては、例えば、還元過程での解離温度(分解温度)が比較的低いギ酸ニッケル、酢酸ニッケルなどを用いることが好ましい。カルボン酸ニッケルは、無水物であってもよく、また水和物であってもよい。なお、カルボン酸ニッケルに代えて、塩化ニッケル、硝酸ニッケル、硫酸ニッケル、炭酸ニッケル、水酸化ニッケル等の無機塩を用いることも考えられるが、無機塩の場合、解離(分解)が高温であるため、還元過程で高温での加熱が必要であり好ましくない。また、Ni(acac)2(β-ジケトナト錯体)、ステアリン酸イオン等の有機配位子により構成されるニッケル塩を用いることも考えられるが、これらのニッケル塩を用いると、原料コストが高くなり好ましくない。 <Metal salt containing nickel carboxylate>
As the nickel carboxylate used in step I, for example, nickel formate, nickel acetate or the like having a relatively low dissociation temperature (decomposition temperature) in the reduction process is preferably used. The nickel carboxylate may be an anhydride or a hydrate. In addition, it is possible to use inorganic salts such as nickel chloride, nickel nitrate, nickel sulfate, nickel carbonate, nickel hydroxide instead of nickel carboxylate, but in the case of inorganic salts, dissociation (decomposition) is high temperature. In the reduction process, heating at a high temperature is necessary, which is not preferable. It is also possible to use nickel salts composed of organic ligands such as Ni (acac) 2 (β-diketonato complex) and stearate ions, but using these nickel salts increases the cost of raw materials. It is not preferable.
脂肪族1級モノアミンは、ニッケルイオンとの錯体を形成できるものであれば、特に限定されず、常温で固体又は液体のものが使用できる。ここで、常温とは、20℃±15℃をいう。常温で液体の脂肪族1級モノアミンは、ニッケル錯体を形成する際の有機溶媒としても機能する。なお、常温で固体の脂肪族1級モノアミンであっても、加熱によって液体であるか、又は有機溶媒を用いて溶解するものであれば、特に問題はない。工程Iにおいて、2級アミンは立体障害が大きいため、ニッケル錯体の良好な形成を阻害するおそれがあり、3級アミンはニッケルイオンの還元能を有しないため、いずれも使用できない。また、ジアミンは、金属イオンの中でも特にニッケルイオンと形成した錯体の安定性が高く、その還元温度は高くなるため反応性が非常に低く、生成するニッケル粒子に歪が生じやすくなるため好ましくない。 <Aliphatic primary monoamine>
The aliphatic primary monoamine is not particularly limited as long as it can form a complex with nickel ions, and can be solid or liquid at room temperature. Here, room temperature means 20 ° C. ± 15 ° C. The aliphatic primary monoamine that is liquid at room temperature also functions as an organic solvent for forming the nickel complex. In addition, even if it is an aliphatic primary monoamine solid at normal temperature, there is no particular problem as long as it is liquid by heating or can be dissolved using an organic solvent. In Step I, secondary amines have great steric hindrance, which may hinder the good formation of nickel complexes, and tertiary amines do not have the ability to reduce nickel ions, so none can be used. Also, diamines are not preferred because of the high stability of complexes formed with nickel ions, among metal ions, and the reduction temperature is high, so that the reactivity is very low and the resulting nickel particles are easily distorted.
脂肪族1級モノアミンは、有機溶媒として反応を進行させることができるが、均一溶液での反応をより効率的に進行させるために、工程Iにおいて、脂肪族1級モノアミンとは別の有機溶媒を新たに添加してもよい。使用できる有機溶媒としては、脂肪族1級モノアミンとニッケルイオンなどの金属イオンとの錯形成を阻害しないものであれば、特に限定するものではなく、例えば炭素数4~30のエーテル系有機溶媒、炭素数7~30の飽和又は不飽和の炭化水素系有機溶媒、炭素数8~18のアルコール系有機溶媒等を使用することができる。また、マイクロ波照射による加熱条件下でも使用を可能とする観点から、使用する有機溶媒は、沸点が170℃以上のものを選択することが好ましく、より好ましくは200~300℃の範囲内にあるものを選択することがよい。このような有機溶媒の具体例としては、例えばテトラエチレングリコール、n-オクチルエーテル、炭素数が20~40の範囲内にあるポリアルファオレフィン等が挙げられる。 <Organic solvent>
Although the aliphatic primary monoamine can proceed as an organic solvent, in order to proceed the reaction in a homogeneous solution more efficiently, an organic solvent different from the aliphatic primary monoamine is used in Step I. You may add newly. The organic solvent that can be used is not particularly limited as long as it does not inhibit complex formation between an aliphatic primary monoamine and a metal ion such as nickel ion. For example, an ether-based organic solvent having 4 to 30 carbon atoms, A saturated or unsaturated hydrocarbon organic solvent having 7 to 30 carbon atoms, an alcohol organic solvent having 8 to 18 carbon atoms, or the like can be used. Further, from the viewpoint of enabling use even under heating conditions by microwave irradiation, it is preferable to select an organic solvent having a boiling point of 170 ° C. or higher, more preferably in the range of 200 to 300 ° C. It is better to choose one. Specific examples of such an organic solvent include tetraethylene glycol, n-octyl ether, polyalphaolefin having a carbon number in the range of 20 to 40, and the like.
工程Iにおいて、種粒子を形成するための加熱方法は、特に制限されず、例えばオイルバスなどの熱媒体による加熱であっても、マイクロ波照射による加熱であってもよいが、マイクロ波照射による加熱が好ましい。マイクロ波照射による加熱は、均一加熱を可能とし、かつエネルギーを金属イオンに直接与えることができるため、急速加熱を行なうことができる。これにより、反応液全体を所望の温度に均一にすることができ、金属イオンの還元、核の形成、成長を溶液全体において同時に生じさせ、結果として粒子径分布の狭い単分散な種粒子を短時間で容易に製造することができる。マイクロ波の使用波長は、特に限定するものではなく、例えば2.45GHzである。 <Heat reduction>
In Step I, the heating method for forming seed particles is not particularly limited, and for example, heating by a heat medium such as an oil bath or heating by microwave irradiation may be used. Heating is preferred. Heating by microwave irradiation enables uniform heating and energy can be directly applied to metal ions, so that rapid heating can be performed. As a result, the entire reaction solution can be made uniform at a desired temperature, and reduction of metal ions, formation of nuclei, and growth occur simultaneously in the entire solution. As a result, monodisperse seed particles having a narrow particle size distribution can be shortened. It can be manufactured easily in time. The use wavelength of the microwave is not particularly limited and is, for example, 2.45 GHz.
工程Iで得られる種粒子の走査型電子顕微鏡観察による平均粒子径D1は、例えば50nm以下が好ましく、10nm以上50nm以下の範囲内がより好ましい。種粒子の平均粒子径D1が10nm未満では、ハンドリング性が低下するとともに、凝集しやすくなって、核剤として用いた場合に、粒子径分布がシャープなニッケル粒子を安定的に製造することが難しくなる。一方、種粒子の平均粒子径D1が50nmを超えると、種粒子の段階での粒子径のばらつきが大きくなって、やはり、核剤として用いた場合に、粒子径分布がシャープなニッケル粒子を安定的に製造することが困難になる。 <Seed particles>
The average particle diameter D1 of the seed particles obtained in the step I by observation with a scanning electron microscope is, for example, preferably 50 nm or less, more preferably in the range of 10 nm to 50 nm. When the average particle diameter D1 of the seed particles is less than 10 nm, the handling property is lowered and the particles are easily aggregated. When used as a nucleating agent, it is difficult to stably produce nickel particles having a sharp particle diameter distribution. Become. On the other hand, when the average particle diameter D1 of the seed particles exceeds 50 nm, the dispersion of the particle diameter at the seed particle stage becomes large, and when used as a nucleating agent, nickel particles having a sharp particle diameter distribution are stable. Manufacturing becomes difficult.
工程IIでは、ニッケル塩と、脂肪族1級モノアミンと、を混合し、加熱することによってニッケル塩を有機アミンに溶解させたニッケル錯体溶液を準備する。 [Step II]
In Step II, a nickel salt solution and an aliphatic primary monoamine are mixed and heated to prepare a nickel complex solution in which the nickel salt is dissolved in an organic amine.
工程IIにおいて、ニッケル塩の種類は特に限定されず、例えば水酸化ニッケル、塩化ニッケル、硝酸ニッケル、硫酸ニッケル、炭酸ニッケル、カルボン酸ニッケル、Ni(acac)2(β-ジケトナト錯体)、ステアリン酸ニッケル等が挙げられるが、この中でも、塩化ニッケル又はカルボン酸ニッケルが好ましく、還元過程での解離温度(分解温度)が比較的低いカルボン酸ニッケルを用いることが有利である。カルボン酸ニッケルは単独で用いてもよいし、他のニッケル塩と併用することもできる。また、カルボン酸ニッケルは、工程Iと同様のものを使用することができる。 <Nickel salt>
In step II, the type of nickel salt is not particularly limited. For example, nickel hydroxide, nickel chloride, nickel nitrate, nickel sulfate, nickel carbonate, nickel carboxylate, Ni (acac) 2 (β-diketonato complex), nickel stearate Among them, nickel chloride or nickel carboxylate is preferable, and it is advantageous to use nickel carboxylate having a relatively low dissociation temperature (decomposition temperature) in the reduction process. The nickel carboxylate may be used alone or in combination with other nickel salts. Moreover, the same thing as the process I can be used for nickel carboxylate.
工程IIにおいて、脂肪族1級モノアミンは、工程Iと同じものを使用することができる。 <Aliphatic primary monoamine>
In Step II, the same aliphatic primary monoamine as in Step I can be used.
ニッケル錯体溶液中のニッケル濃度は、例えば2~13重量%の範囲内とすることが好ましく、6~12重量%の範囲内とすることがより好ましい。本実施の形態の製造方法では、種粒子を形成する工程Iと、種粒子からニッケル粒子を成長させる工程IVを区別する多段階の反応によって、一段階の合成法に比べ、ニッケル錯体溶液中のニッケルの濃度を高めることが可能であり、生産性を向上させることができる。一段階の合成法では、ニッケル濃度が10重量%を超えると、反応性が低下するとともに、粒子径の制御が難しくなる。 <Nickel complex solution>
The nickel concentration in the nickel complex solution is, for example, preferably in the range of 2 to 13% by weight, and more preferably in the range of 6 to 12% by weight. In the manufacturing method of the present embodiment, a multi-step reaction that distinguishes Step I for forming seed particles and Step IV for growing nickel particles from the seed particles, and compared with a one-step synthesis method, The concentration of nickel can be increased and productivity can be improved. In the one-step synthesis method, when the nickel concentration exceeds 10% by weight, the reactivity is lowered and the particle size is difficult to control.
本工程は、工程Iで得た種粒子と、工程IIで得たニッケル錯体溶液とを混合して混合液を得る工程である。 [Step III]
This step is a step in which the seed particles obtained in Step I and the nickel complex solution obtained in Step II are mixed to obtain a mixed solution.
D2=D1(1+Y/X)1/3 ・・・(1)
[ここで、式(1)において、D2はニッケル粒子の平均粒子径(単位;nm)であり、D1は種粒子の平均粒子径(単位;nm)であり、Yは混合液中のニッケル錯体中のニッケル量(単位;g)であり、Xは種粒子中のニッケル量(単位;g)である。] In Step III, seed particles or a slurry containing seed particles may be added to the nickel complex solution, or a nickel complex solution may be added to the slurry containing seed particles. The nickel complex mixed in step III is not used for the formation of new nuclei, but is used for the growth from seed particles to nickel particles in the next step IV. That is, as long as the concentration of the nickel complex in the mixed solution does not exceed the critical concentration for nucleation, the nickel complex is used only for particle growth. Therefore, the amount of the nickel complex for obtaining nickel particles having the target particle size in Step IV can be calculated based on the particle size of the seed particles. In this step, the nickel concentration in the nickel complex in the mixed solution can be calculated by, for example, the following formula (1). For example, when nickel particles having an average particle size in the range of 20 to 150 nm are obtained using seed particles having an average particle size in the range of 10 to 50 nm and a coefficient of variation of the particle size of 0.2 or less, The nickel concentration in the nickel complex in the liquid is preferably in the range of 4 to 13% by weight, for example, and more preferably in the range of 6 to 12% by weight.
D2 = D1 (1 + Y / X) 1/3 (1)
[Wherein, in Formula (1), D2 is the average particle size (unit; nm) of the nickel particles, D1 is the average particle size (unit: nm) of the seed particles, and Y is the nickel complex in the mixed solution] Is the amount of nickel in the unit (g), and X is the amount of nickel in the seed particles (unit: g). ]
工程IVは、工程IIIで得た混合液中のニッケルイオンを加熱還元し、前記種粒子を核として金属ニッケルを析出・成長させてニッケル粒子を形成する。 [Step IV]
In the step IV, nickel ions in the mixed liquid obtained in the step III are heated and reduced, and nickel particles are formed by depositing and growing nickel metal with the seed particles as nuclei.
工程IVにおける加熱方法は、特に制限されず、例えばオイルバスなどの熱媒体による加熱であっても、マイクロ波照射による加熱であってもよいが、マイクロ波照射による加熱が好ましい。マイクロ波照射によるニッケル錯体の加熱は、ニッケル錯体の均一加熱を可能とし、かつエネルギーをニッケル錯体に直接与えることができるため、急速加熱を行なうことができる。これにより、反応液全体を所望の温度に均一にすることができ、ニッケル錯体(又はニッケルイオン)の還元と成長を溶液全体において同時に生じさせ、結果として粒子径分布の狭い単分散なニッケル粒子を短時間で容易に製造することができる。マイクロ波の使用波長は、特に限定するものではなく、例えば2.45GHzである。 <Heat reduction>
The heating method in Step IV is not particularly limited, and for example, heating by a heat medium such as an oil bath or heating by microwave irradiation may be used, but heating by microwave irradiation is preferable. Heating of the nickel complex by microwave irradiation enables uniform heating of the nickel complex and energy can be directly applied to the nickel complex, so that rapid heating can be performed. As a result, the entire reaction solution can be made uniform at a desired temperature, and the reduction and growth of the nickel complex (or nickel ions) can occur simultaneously in the entire solution, resulting in monodisperse nickel particles having a narrow particle size distribution. It can be easily manufactured in a short time. The use wavelength of the microwave is not particularly limited and is, for example, 2.45 GHz.
工程IVで得られるニッケル粒子は、例えば球状、擬球状、長球状、立方体様、切頭四面体様、双角錐状、正八面体様、正十面体様、正二十面体様等の種々の形状であってよいが、例えばニッケル粒子を電子部品の電極に使用した場合の充填密度の向上という観点から、球状又は擬球状が好ましく、球状がより好ましい。ここで、ニッケル粒子の形状は、例えば、走査型電子顕微鏡(SEM)で観察することにより確認できる。 <Nickel particles>
The nickel particles obtained in step IV are various shapes such as spherical, pseudospherical, oblong, cubic, truncated tetrahedral, dihedral pyramid, octahedral, icosahedral, icosahedral, etc. However, from the viewpoint of improving the packing density when nickel particles are used for an electrode of an electronic component, for example, spherical or pseudospherical is preferable, and spherical is more preferable. Here, the shape of the nickel particles can be confirmed by observing with a scanning electron microscope (SEM), for example.
本実施の形態のニッケル粒子の製造方法において、従来の一段階の合成法に比べて、精度の高い粒子径の制御が可能となる理由は明らかではないが、以下のように考えれば合理的説明が可能になる。従来の一段階の合成法、すなわち核生成からニッケル粒子の成長までをワンポットで行う方法では、その反応系の環境因子(例えば、反応液の濃度、撹拌条件、水分、反応速度に影響を与える天然物原料に由来する微量の不純物や微量金属の存在など)が、ニッケル粒子の成長に大きく影響を与えることから、粒子径の制御が困難となる。一方、本実施の形態のニッケル粒子の製造方法では、反応系の環境因子の影響が出やすい工程Iにおいて、生成する種粒子は粒子径が小さいので、その分、粒子径のバラツキを低く抑えることができる。そして、ニッケル粒子を成長させる工程IVにおいては、反応系の環境因子よりも、種粒子のほうがニッケル粒子の成長に大きな影響を与える因子となるので、最終的に製造されるニッケル粒子の粒子径を高精度に制御できるものと考えられる。 <Action>
In the nickel particle manufacturing method of the present embodiment, the reason why it is possible to control the particle diameter with high accuracy compared to the conventional one-step synthesis method is not clear, but it is reasonable to consider it as follows. Is possible. In the conventional one-step synthesis method, that is, the method of performing nucleation to nickel particle growth in a single pot, the environmental factors of the reaction system (for example, the concentration of the reaction solution, stirring conditions, moisture, and the natural rate affecting the reaction rate) The presence of trace amounts of impurities and trace metals derived from raw materials greatly affects the growth of nickel particles, making it difficult to control the particle size. On the other hand, in the method for producing nickel particles according to the present embodiment, since the seed particles to be generated have a small particle size in the step I where the influence of environmental factors of the reaction system is likely to occur, the variation in the particle size is suppressed accordingly. Can do. In Step IV where nickel particles are grown, seed particles have a greater influence on nickel particle growth than environmental factors in the reaction system. It is thought that it can be controlled with high accuracy.
SEM(走査型電子顕微鏡)により試料の写真を撮影して、その中から無作為に200個を抽出してそれぞれの粒子径について面積を求め、真球に換算したときの粒子径を個数基準として一次粒子の平均粒子径とした。また、CV値(変動係数)は、(標準偏差)÷(平均粒子径)によって算出した。なお、CV値が小さいほど、粒子径がより均一であることを示す。 [Measurement of average particle size]
Take a photograph of the sample with an SEM (scanning electron microscope), extract 200 samples randomly from it, determine the area for each particle size, and use the particle size when converted to a true sphere as the number standard The average particle size of the primary particles was used. The CV value (coefficient of variation) was calculated by (standard deviation) / (average particle diameter). In addition, it shows that a particle diameter is so uniform that a CV value is small.
<工程I;第1のニッケル粒子の調製>
331gのオレイルアミンに2.45gのギ酸銅四水和物と21.9gのギ酸ニッケル二水和物を加え、窒素フロー下で120℃、20分加熱することでギ酸銅とギ酸ニッケルをオレイルアミンに溶解した。 (Example 1)
<Step I: Preparation of first nickel particles>
Add 2.45 g of copper formate tetrahydrate and 21.9 g of nickel formate dihydrate to 331 g of oleylamine, and dissolve copper formate and nickel formate in oleylamine by heating at 120 ° C for 20 minutes under nitrogen flow. did.
6949gのオレイルアミンに2611gの酢酸ニッケル四水和物を加え、窒素フロー下で140℃、4時間加熱することでニッケル錯体溶液を調製した。 <Step II: Preparation of nickel complex solution>
A nickel complex solution was prepared by adding 2611 g of nickel acetate tetrahydrate to 6949 g of oleylamine and heating at 140 ° C. for 4 hours under a nitrogen flow.
上記のニッケル錯体溶液に、337gのニッケル粒子スラリー(1-A)を加え、撹拌後、マイクロ波を照射して225℃まで加熱し、その温度を15分間保持することによってニッケル粒子スラリー(1-C)を調製した。得られたニッケル粒子スラリー(1-C)を静置分離し、上澄み液を取り除いた後、トルエンとメタノールを用いてそれぞれ2回洗浄した後、60℃に維持される真空乾燥機で6時間乾燥してニッケル粒子(1-D)を調製した。 <Steps III to IV: Preparation of mixed solution and preparation of nickel particles>
To the above nickel complex solution, 337 g of the nickel particle slurry (1-A) is added, stirred, heated to 225 ° C. by microwave irradiation, and maintained at that temperature for 15 minutes to maintain the nickel particle slurry (1- C) was prepared. The resulting nickel particle slurry (1-C) was allowed to stand and separated, the supernatant was removed, washed twice with toluene and methanol, and then dried in a vacuum dryer maintained at 60 ° C. for 6 hours. Thus, nickel particles (1-D) were prepared.
<工程I;第1のニッケル粒子の調製>
実施例1におけるギ酸銅四水和物の使用量を0.61gに変更したこと以外、実施例1と同様にして、ギ酸銅とギ酸ニッケルをオレイルアミンに溶解した。 (Example 2)
<Step I: Preparation of first nickel particles>
Copper formate and nickel formate were dissolved in oleylamine in the same manner as in Example 1 except that the amount of copper formate tetrahydrate used in Example 1 was changed to 0.61 g.
1977gのドデシルアミンに882gの酢酸ニッケル四水和物を加え、実施例1と同様にして、ニッケル錯体溶液を調製した。 <Step II: Preparation of nickel complex solution>
A nickel complex solution was prepared in the same manner as in Example 1 by adding 882 g of nickel acetate tetrahydrate to 1977 g of dodecylamine.
上記のニッケル錯体溶液に、333gのニッケル粒子スラリー(2-A)を加え、実施例1と同様にして、ニッケル粒子スラリー(2-C)を得、トルエンとメタノールを用いて洗浄後、乾燥してニッケル粒子(2-D)を調製した。SEM写真の結果から、ニッケル粒子(2-D)の平均粒子径は141nm、CV値は0.14であった。 <Steps III to IV: Preparation of mixed solution and preparation of nickel particles>
To the above nickel complex solution, 333 g of nickel particle slurry (2-A) was added to obtain nickel particle slurry (2-C) in the same manner as in Example 1, washed with toluene and methanol, and then dried. Thus, nickel particles (2-D) were prepared. From the results of the SEM photograph, the average particle diameter of the nickel particles (2-D) was 141 nm, and the CV value was 0.14.
<工程I;第1のニッケル粒子の調製>
実施例1における331gのオレイルアミンの代わりに、314gのドデシルアミンを使用したこと、並びにギ酸銅四水和物及びギ酸ニッケル二水和物の使用量をそれぞれ0.49g、43.8gに変更したこと以外、実施例1と同様にして、ギ酸銅とギ酸ニッケルをドデシルアミンに溶解した。 (Example 3)
<Step I: Preparation of first nickel particles>
In place of 331 g of oleylamine in Example 1, 314 g of dodecylamine was used, and the amounts of copper formate tetrahydrate and nickel formate dihydrate were changed to 0.49 g and 43.8 g, respectively. Except for this, copper formate and nickel formate were dissolved in dodecylamine in the same manner as in Example 1.
4028gのドデシルアミンに1797gの酢酸ニッケル四水和物を加え、実施例1と同様にして、ニッケル錯体溶液を調製した。 <Step II: Preparation of nickel complex solution>
A nickel complex solution was prepared in the same manner as in Example 1 by adding 1797 g of nickel acetate tetrahydrate to 4028 g of dodecylamine.
上記のニッケル錯体溶液に、332gのニッケル粒子スラリー(3-A)を加え、実施例1と同様にして、ニッケル粒子スラリー(3-C)を得、トルエンとメタノールを用いて洗浄後、乾燥してニッケル粒子(3-D)を調製した。SEM写真の結果から、ニッケル粒子(3-D)の平均粒子径は63nm、CV値は0.10であった。 <Steps III to IV: Preparation of mixed solution and preparation of nickel particles>
To the above nickel complex solution, 332 g of nickel particle slurry (3-A) was added to obtain nickel particle slurry (3-C) in the same manner as in Example 1, washed with toluene and methanol, and then dried. Thus, nickel particles (3-D) were prepared. From the result of the SEM photograph, the average particle diameter of the nickel particles (3-D) was 63 nm, and the CV value was 0.10.
<工程I;第1のニッケル粒子の調製>
実施例1における331gのオレイルアミンの代わりに、297gのオクチルアミンを使用したこと、並びにギ酸銅四水和物及びギ酸ニッケル二水和物の使用量をそれぞれ0.98g、65.7gに変更したこと以外、実施例1と同様にして、ギ酸銅とギ酸ニッケルをオクチルアミンに溶解した。 Example 4
<Step I: Preparation of first nickel particles>
297 g of octylamine was used instead of 331 g of oleylamine in Example 1, and the amounts of copper formate tetrahydrate and nickel formate dihydrate were changed to 0.98 g and 65.7 g, respectively. Except for the above, copper formate and nickel formate were dissolved in octylamine in the same manner as in Example 1.
1050gのオクチルアミンに636gの酢酸ニッケル四水和物を加え、窒素フロー下で120℃、4時間加熱することでニッケル錯体溶液を調製した。 <Step II: Preparation of nickel complex solution>
A nickel complex solution was prepared by adding 636 g of nickel acetate tetrahydrate to 1050 g of octylamine and heating at 120 ° C. for 4 hours under a nitrogen flow.
上記のニッケル錯体溶液に、337gのニッケル粒子スラリー(4-A)を加え、撹拌後、マイクロ波を照射して170℃まで加熱し、その温度を60分間保持することによってニッケル粒子スラリー(4-C)を調製した。得られたニッケル粒子スラリー(4-C)を実施例1と同様にして処理して、ニッケル粒子(4-D)を調製した。SEM写真の結果から、ニッケル粒子(4-D)の平均粒子径は30nm、CV値は0.13であった。 <Steps III to IV: Preparation of mixed solution and preparation of nickel particles>
To the above nickel complex solution, 337 g of the nickel particle slurry (4-A) is added, stirred, heated to 170 ° C. by irradiation with microwaves, and the temperature is maintained for 60 minutes to maintain the nickel particle slurry (4- C) was prepared. The obtained nickel particle slurry (4-C) was treated in the same manner as in Example 1 to prepare nickel particles (4-D). From the result of the SEM photograph, the average particle diameter of the nickel particles (4-D) was 30 nm, and the CV value was 0.13.
<工程I;第1のニッケル粒子の調製>
実施例1におけるギ酸銅四水和物を使用しなかったこと以外、実施例1と同様にして、ギ酸ニッケルをオレイルアミンに溶解した。 (Example 5)
<Step I: Preparation of first nickel particles>
Nickel formate was dissolved in oleylamine in the same manner as in Example 1 except that the copper formate tetrahydrate in Example 1 was not used.
1918gのオクチルアミンに1526gの酢酸ニッケル四水和物を加え、窒素フロー下で120℃、4時間加熱することでニッケル錯体溶液を調製した。 <Step II: Preparation of nickel complex solution>
A nickel complex solution was prepared by adding 1526 g of nickel acetate tetrahydrate to 1918 g of octylamine and heating at 120 ° C. for 4 hours under a nitrogen flow.
上記のニッケル錯体溶液に、335gのニッケル粒子スラリー(5-A)を加え、撹拌後、マイクロ波を照射して170℃まで加熱し、その温度を60分間保持することによってニッケル粒子スラリー(5-C)を調製した。得られたニッケル粒子スラリー(5-C)を実施例1と同様にして処理して、ニッケル粒子(5-D)を調製した。SEM写真の結果から、ニッケル粒子(5-D)の平均粒子径は112nm、CV値は0.15であった。 <Steps III to IV: Preparation of mixed solution and preparation of nickel particles>
To the above nickel complex solution, 335 g of nickel particle slurry (5-A) is added, and after stirring, heated to 170 ° C. by irradiation with microwaves and maintained at that temperature for 60 minutes to maintain the nickel particle slurry (5- C) was prepared. The obtained nickel particle slurry (5-C) was treated in the same manner as in Example 1 to prepare nickel particles (5-D). From the results of the SEM photograph, the average particle diameter of the nickel particles (5-D) was 112 nm, and the CV value was 0.15.
<工程I;第1のニッケル粒子の調製>
実施例1における2.45gのギ酸銅四水和物の代わりに、0.036gの酢酸パラジウムを使用したこと以外、実施例1と同様にして、酢酸パラジウム及びギ酸ニッケルをオレイルアミンに溶解した。 (Example 6)
<Step I: Preparation of first nickel particles>
Palladium acetate and nickel formate were dissolved in oleylamine in the same manner as in Example 1 except that 0.036 g of palladium acetate was used instead of 2.45 g of copper formate tetrahydrate in Example 1.
1216gのオレイルアミンに543gの酢酸ニッケル四水和物を加え、窒素フロー下で140℃、4時間加熱することでニッケル錯体溶液を調製した。 <Step II: Preparation of nickel complex solution>
A nickel complex solution was prepared by adding 543 g of nickel acetate tetrahydrate to 1216 g of oleylamine and heating at 140 ° C. for 4 hours under a nitrogen flow.
上記のニッケル錯体溶液に、334gのニッケル粒子スラリー(6-A)を加え、実施例1と同様にして、ニッケル粒子スラリー(6-C)を調製した。得られたニッケル粒子スラリー(6-C)を実施例1と同様にして処理して、ニッケル粒子(6-D)を調製した。SEM写真の結果から、ニッケル粒子(6-D)の平均粒子径は120nm、CV値は0.13であった。 <Steps III to IV: Preparation of mixed solution and preparation of nickel particles>
334 g of nickel particle slurry (6-A) was added to the above nickel complex solution, and nickel particle slurry (6-C) was prepared in the same manner as in Example 1. The obtained nickel particle slurry (6-C) was treated in the same manner as in Example 1 to prepare nickel particles (6-D). From the result of the SEM photograph, the average particle diameter of the nickel particles (6-D) was 120 nm, and the CV value was 0.13.
<工程I;第1のニッケル粒子の調製>
330gのオレイルアミンに29.7gの酢酸ニッケル四水和物を加え、窒素フロー下で120℃、20分加熱することで酢酸ニッケルをオレイルアミンに溶解した。 (Example 7)
<Step I: Preparation of first nickel particles>
29.7 g of nickel acetate tetrahydrate was added to 330 g of oleylamine, and nickel acetate was dissolved in oleylamine by heating at 120 ° C. for 20 minutes under a nitrogen flow.
5092gのドデシルアミンに2670gの酢酸ニッケル四水和物を加え、窒素フロー下で140℃、4時間加熱することでニッケル錯体溶液を調製した。 <Step II: Preparation of nickel complex solution>
A nickel complex solution was prepared by adding 2670 g of nickel acetate tetrahydrate to 5092 g of dodecylamine and heating at 140 ° C. for 4 hours under a nitrogen flow.
上記のニッケル錯体溶液に、336gのニッケル粒子スラリー(7-A)を加え、実施例1と同様にして、ニッケル粒子スラリー(7-C)を調製した。得られたニッケル粒子スラリー(7-C)を実施例1と同様に処理して、ニッケル粒子(7-D)を調製した。SEM写真の結果から、ニッケル粒子(7-D)の平均粒子径は85nm、CV値は0.11であった。 <Steps III to IV: Preparation of mixed solution and preparation of nickel particles>
To the above nickel complex solution, 336 g of nickel particle slurry (7-A) was added, and nickel particle slurry (7-C) was prepared in the same manner as in Example 1. The obtained nickel particle slurry (7-C) was treated in the same manner as in Example 1 to prepare nickel particles (7-D). From the result of the SEM photograph, the average particle diameter of the nickel particles (7-D) was 85 nm, and the CV value was 0.11.
<工程I;第1のニッケル粒子の調製>
307gのドデシルアミンに59.3gの酢酸ニッケル四水和物を加え、窒素フロー下で120℃、20分加熱することで酢酸ニッケルをドデシルアミンに溶解した。 (Example 8)
<Step I: Preparation of first nickel particles>
59.3 g of nickel acetate tetrahydrate was added to 307 g of dodecylamine, and nickel acetate was dissolved in dodecylamine by heating at 120 ° C. for 20 minutes under a nitrogen flow.
2730gのオクチルアミンに1653gの酢酸ニッケル四水和物を加え、窒素フロー下で120℃、4時間加熱することでニッケル錯体溶液を調製した。 <Step II: Preparation of nickel complex solution>
A nickel complex solution was prepared by adding 1653 g of nickel acetate tetrahydrate to 2730 g of octylamine and heating at 120 ° C. for 4 hours under a nitrogen flow.
上記のニッケル錯体溶液に、338gのニッケル粒子スラリー(8-A)を加え、撹拌後、マイクロ波を照射して170℃まで加熱し、その温度を60分間保持することによってニッケル粒子スラリー(8-C)を調製した。得られたニッケル粒子スラリー(8-C)を実施例1と同様にして処理して、ニッケル粒子(8-D)を調製した。SEM写真の結果から、ニッケル粒子(8-D)の平均粒子径は92nm、CV値は0.15であった。 <Steps III to IV: Preparation of mixed solution and preparation of nickel particles>
To the above nickel complex solution, 338 g of the nickel particle slurry (8-A) was added, stirred, heated to 170 ° C. by microwave irradiation, and maintained at that temperature for 60 minutes to maintain the nickel particle slurry (8- C) was prepared. The obtained nickel particle slurry (8-C) was treated in the same manner as in Example 1 to prepare nickel particles (8-D). From the result of the SEM photograph, the average particle diameter of the nickel particles (8-D) was 92 nm, and the CV value was 0.15.
<工程I;第1のニッケル粒子の調製>
実施例8と同様にして、酢酸ニッケルをドデシルアミンに溶解した。 Example 9
<Step I: Preparation of first nickel particles>
In the same manner as in Example 8, nickel acetate was dissolved in dodecylamine.
実施例8と同様にして、ニッケル錯体溶液を調製した。 <Step II: Preparation of nickel complex solution>
In the same manner as in Example 8, a nickel complex solution was prepared.
上記のニッケル錯体溶液に、338gのニッケル粒子スラリー(9-A)を加え、実施例8と同様にして、ニッケル粒子スラリー(9-C)を調製した。得られたニッケル粒子スラリー(9-C)を実施例8と同様にして処理して、ニッケル粒子(9-D)を調製した。SEM写真の結果から、ニッケル粒子(9-D)の平均粒子径は41nm、CV値は0.13であった。 <Steps III to IV: Preparation of mixed solution and preparation of nickel particles>
To the above nickel complex solution, 338 g of nickel particle slurry (9-A) was added, and in the same manner as in Example 8, a nickel particle slurry (9-C) was prepared. The obtained nickel particle slurry (9-C) was treated in the same manner as in Example 8 to prepare nickel particles (9-D). From the result of the SEM photograph, the average particle diameter of the nickel particles (9-D) was 41 nm, and the CV value was 0.13.
<工程I;第1のニッケル粒子の調製>
287gのオクチルアミンに0.29gの酢酸パラジウムと89.1gの酢酸ニッケル四水和物を加え、窒素フロー下で120℃、20分加熱することで酢酸パラジウムと酢酸ニッケルをオクチルアミンに溶解した。 (Example 10)
<Step I: Preparation of first nickel particles>
To 287 g of octylamine were added 0.29 g of palladium acetate and 89.1 g of nickel acetate tetrahydrate, and the mixture was heated at 120 ° C. for 20 minutes under a nitrogen flow to dissolve palladium acetate and nickel acetate in octylamine.
1819gのオクチルアミンに954gの酢酸ニッケル四水和物を加え、窒素フロー下で120℃、4時間加熱することでニッケル錯体溶液を調製した。 <Step II: Preparation of nickel complex solution>
A nickel complex solution was prepared by adding 954 g of nickel acetate tetrahydrate to 1819 g of octylamine and heating at 120 ° C. for 4 hours under a nitrogen flow.
上記のニッケル錯体溶液に、337gのニッケル粒子スラリー(10-A)を加え、撹拌後、マイクロ波を照射して170℃まで加熱し、その温度を60分間保持することによってニッケル粒子スラリー(10-C)を調製した。得られたニッケル粒子スラリー(10-C)を実施例1と同様に処理して、ニッケル粒子(10-D)を調製した。SEM写真の結果から、ニッケル粒子(10-D)の平均粒子径は77nm、CV値は0.14であった。 <Steps III to IV: Preparation of mixed solution and preparation of nickel particles>
To the above nickel complex solution, 337 g of nickel particle slurry (10-A) was added, stirred, heated to 170 ° C. by microwave irradiation, and held at that temperature for 60 minutes to maintain the nickel particle slurry (10-A). C) was prepared. The obtained nickel particle slurry (10-C) was treated in the same manner as in Example 1 to prepare nickel particles (10-D). From the result of the SEM photograph, the average particle diameter of the nickel particles (10-D) was 77 nm, and the CV value was 0.14.
Claims (6)
- ニッケル粒子の製造方法であって、下記の工程I~IV;
I)少なくともカルボン酸ニッケルを含む金属塩と、脂肪族1級モノアミンと、を混合し、加熱することによって種粒子を形成する工程、
II)ニッケル塩と、脂肪族1級モノアミンと、を混合し、加熱することによって、ニッケル塩を有機アミンに溶解させたニッケル錯体溶液を準備する工程、
III)前記種粒子と前記ニッケル錯体溶液とを混合して混合液を得る工程、
IV)前記混合液中のニッケルイオンを加熱還元し、前記種粒子を核として金属ニッケルを析出・成長させてニッケル粒子を形成する工程、
を備えることを特徴とするニッケル粒子の製造方法。 A method for producing nickel particles, comprising the following steps I to IV:
I) A step of forming seed particles by mixing and heating a metal salt containing at least nickel carboxylate and an aliphatic primary monoamine.
II) A step of preparing a nickel complex solution in which a nickel salt is dissolved in an organic amine by mixing and heating the nickel salt and an aliphatic primary monoamine,
III) A step of mixing the seed particles and the nickel complex solution to obtain a mixed solution,
IV) Step of forming nickel particles by heating and reducing nickel ions in the mixed solution, and depositing and growing nickel metal with the seed particles as nuclei,
A method for producing nickel particles, comprising: - 走査型電子顕微鏡観察による、前記種粒子の平均粒子径D1が10nm以上50nm以下の範囲内であり、前記ニッケル粒子の平均粒子径D2が20nm以上150nm以下の範囲内であり、かつ、8≧D2/D1である請求項1のニッケル粒子の製造方法。 According to the observation with a scanning electron microscope, the average particle diameter D1 of the seed particles is in the range of 10 nm to 50 nm, the average particle diameter D2 of the nickel particles is in the range of 20 nm to 150 nm, and 8 ≧ D2 The method for producing nickel particles according to claim 1, which is / D1.
- 前記種粒子の粒子径の変動係数CV1及び前記ニッケル粒子の粒子径の変動係数CV2がいずれも0.2以下であり、その比(CV1/CV2)が0.7以上1.3以内の範囲内である請求項1又は2に記載のニッケル粒子の製造方法。 Both the variation coefficient CV1 of the particle size of the seed particles and the variation coefficient CV2 of the particle size of the nickel particles are 0.2 or less, and the ratio (CV1 / CV2) is within the range of 0.7 to 1.3. The method for producing nickel particles according to claim 1 or 2.
- 前記工程IIで用いる前記脂肪族1級モノアミンは、炭素数が6以上20以下の範囲内である請求項1から3のいずれか1項に記載のニッケル粒子の製造方法。 The method for producing nickel particles according to any one of claims 1 to 3, wherein the aliphatic primary monoamine used in Step II has a carbon number in the range of 6 to 20.
- 前記金属塩が、カルボン酸ニッケルと、銅、銀、金、白金及びパラジウムから選ばれる1種以上の金属の塩と、を含む請求項1から4のいずれか1項に記載のニッケル粒子の製造方法。 The nickel particles according to any one of claims 1 to 4, wherein the metal salt includes nickel carboxylate and a salt of one or more metals selected from copper, silver, gold, platinum, and palladium. Method.
- 前記工程I及び前記工程IVの加熱をマイクロ波によって行う請求項1から5のいずれか1項に記載のニッケル粒子の製造方法。
The method for producing nickel particles according to any one of claims 1 to 5, wherein the heating in the step I and the step IV is performed by microwaves.
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