JP6713662B2 - Method for producing metal nanoparticles - Google Patents

Description

The present invention relates to a novel method for producing metal nanoparticles.

It is generally known that the melting point of metal nanoparticles having a particle size of less than 100 nm is lower than that of bulk metal. Since it is expected that a low-temperature sintering process will be realized in the metal nanoparticles having such properties, application research to electronics packaging technology is being actively conducted.

The electronics mounting technology is a technology for joining electronic parts to a printed wiring board inside an electronic device with a solder material, and conventionally a solder paste obtained by kneading solder particles and a paste-like flux has been used. .. Common solder particles for solder paste are metal particles containing tin as a main component, and those having a particle diameter of several to several tens of μm are mainly used. For example, solder paste is printed on a printed wiring board by a screen printer, and the solder particles are melted and integrated by reflow (heating) after mounting so that the terminals of electronic parts are in contact Wiring is formed.

In recent years, mobile electronic devices such as mobile phones and notebook computers have been rapidly reduced in size and improved in performance, so that electronic components mounted therein are also becoming smaller and higher in density. Therefore, the printing area of the solder paste is remarkably narrowed, and the solder particles blended in the solder paste are required to be finer. At present, development of solder particles having a particle diameter of several tens to several hundreds of nm is beginning to be required.

Regarding the production of metal nanoparticles, a method of reducing in a solvent to deposit a metal is known. For example, a method of synthesizing metal nanoparticles containing silver as a main component by mixing an aqueous solution of a reducing agent with a suspension prepared based on a metal salt of a carboxylic acid (Patent Document 1), a protecting agent that is an organic amine, and ascorbin. A method of synthesizing metal nanoparticles in which a noble metal is coated with copper using a reducing agent such as an acid (Patent Document 2) and a method of forming tin nanoparticles in the voids of apoferritin (Patent Document 3) have been proposed. There is.

Patent No. 5560459 JP2012-184506A JP-A-2009-35773

However, these conventional methods have room for further improvement in order to efficiently produce nanoparticles of tens to hundreds of nm. For example, it is difficult to efficiently manufacture tin, which is the main component of conventional solder, into nanoparticles of several tens to several hundreds of nm.

The reason is that the method of Patent Document 1 requires the coexistence of silver and cannot produce fine particles of tin alone. In the method of Patent Document 2, the range of application is limited to metal species that are easily reduced. Since the method of Patent Document 3 requires a specific protein called apoferritin and the metal concentration is limited to 10 mM or less, it can be said that it is not suitable for mass production on an industrial scale.

As described above, in the conventional method for producing metal nanoparticles, it is difficult to efficiently synthesize tin nanoparticles having a particle size of several tens to several hundreds nm, and therefore, when applying the metal nanoparticles to the field of electronic packaging. Inevitably, it is necessary to rely on expensive noble metals such as gold, platinum and silver instead of tin, which is the mainstream of solder, and this is an obstacle to cost reduction of products.

Therefore, a main object of the present invention is to provide a method capable of efficiently synthesizing various kinds of metal nanoparticles including metal tin nanoparticles.

The present inventor has conducted intensive studies in view of the problems of the prior art, and as a result, found that the above object can be achieved by adopting a specific process, and completed the present invention.

That is, the present invention relates to the following method for producing metal nanoparticles.
1. A method for producing metal nanoparticles in a liquid phase, comprising the step of producing metal nanoparticles by adding a reducing agent to a metal ion-containing solution in which a surfactant and a metal are dissolved in an aqueous solvent. A method for producing a characteristic metal nanoparticle.
2. Item 2. The production method according to Item 1, wherein the aqueous solvent contains 5% by mass or more of water and 95% by mass or less of a water-soluble organic solvent.
3. Item 3. The production method according to Item 2, wherein the water-soluble organic solvent contains a monohydric alcohol.
4. Item 2. The production method according to Item 1, wherein the surfactant contains at least one of a polyoxyethylene hydrogenated castor oil-based surfactant and a polyoxyethylene castor oil-based surfactant.
5. Item 2. The production method according to Item 1, wherein the produced metal nanoparticles have an average particle diameter of 10 to 500 nm.
6. In the cumulative volume particle size distribution of the generated metal nanoparticles,
(1) The particle size corresponding to 10% by volume of the distribution is 0.5 times or more the particle size corresponding to 50% by volume of the distribution, and
(2) The particle size corresponding to 90% by volume of the distribution is 1.5 times or less the particle size corresponding to 50% by volume of the distribution,
2. The manufacturing method according to 1 above.

According to the production method of the present invention, various kinds of metal nanoparticles including metal tin nanoparticles can be efficiently synthesized. That is, the present invention can provide a method suitable for producing tin nanoparticles and the like on an industrial scale. More specifically, the following effects can be obtained.

(1) Since it is possible to obtain tin nanoparticles having an average particle diameter of several tens to several hundreds nm and a relatively uniform particle diameter, it is possible to obtain the bonding reliability equivalent to that of the conventional solder and Also enables fine solder joints.

(2) Since tin nanoparticles and the like are obtained in a dispersion state and the solvent can be replaced without undergoing a particle drying step, a high quality solder paste product in which a good dispersion state of particles is maintained is obtained. Can be provided.

(3) Since it can be applied to various metals other than tin, it is widely used not only for electronic packaging (especially for soldering electronic parts or forming conductors) but also for pharmaceuticals, foods, cosmetics, paints, catalysts, etc. can do.

It is a flowchart which shows an example of the manufacturing method of this invention. 3 is a view showing an electron micrograph of metal nanoparticles obtained in Example 1. FIG. It is a figure which shows the integrated volume particle diameter distribution of the metal nanoparticles (powder) prepared in Examples 1-8.

The production method of the present invention is a method for producing metal nanoparticles in a liquid phase, in which a metal ion-containing solution in which a surfactant and a metal are dissolved in an aqueous solvent is added to the metal nanoparticles by adding a reducing agent. It is characterized by including a step of generating. A flow showing an example of the manufacturing method of the present invention is shown in FIG.

In the present invention, a metal ion-containing solution in which a surfactant and a metal are dissolved in an aqueous solvent is used as a starting material.

The metal is not particularly limited, and various metal species can be applied. For example, aluminum (Al), scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu). ), zinc (Zn), gallium (Ga), germanium (Ge), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh). ), palladium (Pd), silver (Ag), cadmium (Cd), indium (In), tin (Sn), platinum (Pt), gold (Au), mercury (Hg), thallium (Tl), lead (Pb). ), bismuth (Bi), and the like. In particular, the present invention is suitable for producing tin (metal tin) nanoparticles.

Therefore, in order to obtain metal ions, a metal compound containing these metals may be used as a supply source. The compound serving as a metal ion supply source is not limited as long as it is a water-soluble metal compound, and examples thereof include metal salts of inorganic acids such as carbonates, chlorides, fluorides, sulfates and nitrates, acetates, oxalates and the like. The metal salts of organic acids can be mentioned. Also, complex salts (or organometallic compounds) such as chloro complex, fluoro complex, cyano complex, hydroxy complex, ammine complex, etc. can be used as the metal ion supply source. These can use 1 type(s) or 2 or more types.

The surfactant may be any one that is water-soluble and can stably maintain the dispersed state of the metal nanoparticles, and examples thereof include anionic surfactants, cationic surfactants, and amphoteric surfactants. , Nonionic surfactants and other various types of surfactants can be appropriately selected. Among these, it is preferable to use a nonionic surfactant because high dispersibility and the like can be obtained. As the nonionic surfactant, for example, polyoxyethylene hydrogenated castor oil, polyoxyethylene castor oil, glycerin fatty acid ester, sucrose fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyglycerin fatty acid ester, polyoxyethylene alkyl ether, poly Examples thereof include oxyethylene polyoxypropylene alkyl ether and lecithin.

In particular, in the present invention, when the metal ion-containing solution contains a monohydric alcohol, it contains at least one selected from polyoxyethylene hydrogenated castor oil-based surfactants and polyoxyethylene castor oil-based surfactants. It is preferable. This makes it possible to produce the metal nanoparticles having a desired particle size distribution more reliably and efficiently.

The amount of the surfactant added may be set to a concentration suitable for stabilizing the dispersion of the metal nanoparticles, and for example, in the range of 0.01 to 20 mass% in the metal ion-containing solution, particularly 1 to 5 It is preferable to set it so as to be mass%.

In the present invention, water alone or a mixed solution of water and a water-soluble organic solvent can be used as the aqueous solvent. The water-soluble organic solvent is not particularly limited, but alcohols can be preferably used. For example, monohydric alcohols such as methanol, ethanol, propanol, isopropyl alcohol and t-butyl alcohol, and polyhydric alcohols such as ethylene glycol, propylene glycol and glycerin can be used. Of these alcohols, monohydric alcohols are particularly preferable in the present invention. This makes it possible to more effectively suppress or prevent phenomena such as agglomeration and coalescence of generated particles, and as a result, it is possible to more reliably obtain metal nanoparticles having high dispersibility.

The content of water and the water-soluble organic solvent in the water-based solvent can be appropriately set according to the type of metal ions, and for example, in the range of 5% by mass or more of water and 95% by mass or less of the water-soluble organic solvent, particularly water. It is preferably within the range of 40 to 80% by mass and the water-soluble organic solvent within 20 to 60% by mass.

In the present invention, an acid or an alkali may be added, if necessary, mainly for the purpose of promoting the dissolution of the metal compound. The acid or alkali is not particularly limited as long as it can dissolve the solute at a desired concentration and does not hinder the progress of the reduction reaction for depositing the metal. Examples of the acid include hydrochloric acid, sulfuric acid, nitric acid and the like. Examples of the alkali include ammonia and sodium hydroxide. These can also be added in the form of an aqueous solution. The addition amount can be appropriately set according to the type of metal compound used and the like.

Metal nanoparticles are produced by adding a reducing agent to such a metal ion-containing solution to produce metal nanoparticles.

The type of the reducing agent may be such that it has a potential on the negative side of the redox potential of the target metal, for example, sodium borohydride, sodium cyanoborohydride, lithium aluminum hydride, ascorbic acid, oxalic acid. , Acetic acid, citric acid, formic acid, hydrazine and the like.

The reducing agent can be added as it is or in the form of a solution. As a solvent for forming a solution form (reducing agent solution), a) water alone, b) water-soluble organic solvent alone, or c) a mixed solvent of water and a water-soluble organic solvent can be used. The water-soluble organic solvent is not particularly limited, but alcohols can be preferably used. For example, monohydric alcohols such as methanol, ethanol, propanol, isopropyl alcohol and t-butyl alcohol, and polyhydric alcohols such as ethylene glycol, propylene glycol and glycerin can be used. Of these alcohols, monohydric alcohols are particularly preferable in the present invention. As a result, it is possible to more effectively suppress or prevent phenomena such as agglomeration and coalescence of generated particles, and as a result, it is possible to more reliably obtain metal nanoparticles having high dispersibility.

Further, a surfactant can be added to the reducing agent solution. The surfactant may be any one that is water-soluble and can stably maintain the dispersed state of the metal nanoparticles, and examples thereof include anionic surfactants, cationic surfactants, and amphoteric surfactants. It may be appropriately selected from various types of surfactants such as nonionic surfactants. Among these, nonionic surfactants are preferable. As the nonionic surfactant, for example, polyoxyethylene hydrogenated castor oil, polyoxyethylene castor oil, glycerin fatty acid ester, sucrose fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyglycerin fatty acid ester, polyoxyethylene alkyl ether, poly Examples thereof include oxyethylene polyoxypropylene alkyl ether and lecithin.

In particular, in the present invention, when the reducing agent solution contains a monohydric alcohol, it may contain at least one selected from polyoxyethylene hydrogenated castor oil-based surfactants and polyoxyethylene castor oil-based surfactants. preferable.

The amount of the surfactant added is not particularly limited, and for example, it is preferable to set it in the range of 0.01 to 20% by mass, particularly 1 to 5% by mass in the reducing agent solution.

The method of adding the reducing agent is not particularly limited, and for example, a method of adding the reducing agent as it is or dropping a solution in advance with a pipette while stirring the metal ion-containing solution can be employed. In particular, a method in which the reducing agent is added dropwise to the metal ion-containing solution while stirring is preferable. By dropping the reducing agent, the metal nanoparticles can be produced in a highly dispersed state without aggregating.

In the present invention, it is preferable to control the concentration of the metal nanoparticles dispersed in the liquid after adding the reducing agent to 1 M or less. By controlling in this way, a highly dispersed dispersion liquid can be obtained more reliably. The control of the above concentration can be appropriately performed by, for example, the amount of the aqueous solvent, the amount of the reducing agent added, and the like. The lower limit of the concentration can be set to, for example, 20 mM, but is not limited to this.

In the present invention, by adding a reducing agent, a dispersion liquid in which metal nanoparticles are uniformly dispersed can be obtained. The metal nanoparticles thus obtained usually have an average particle size in the range of 10 to 500 nm and have relatively uniform particle sizes. Here, the average particle diameter of the present invention generally indicates an average value of particle diameters of 100 to 200 particles arbitrarily specified by observation with a scanning electron microscope.

The particle size distribution of the metal nanoparticles (powder) is preferably, in the cumulative volume particle size distribution of the metal nanoparticles,
(1) The particle diameter corresponding to 10% by volume of the distribution is 0.5 times or more the particle diameter corresponding to 50% by volume of the distribution (D10/D50 value is 0.5 or more),
(2) The particle size corresponding to 90% by volume of the distribution is 1.5 times or less the particle size corresponding to 50% by volume of the distribution (D90/D50 value is 1.5 or less).
Is characterized in that The particle group (powder) having such a particle size distribution has a relatively uniform particle diameter. The upper limit value of D10/D50 is not limited and can be set to about 0.9, for example. The lower limit value of D90/D50 is not limited and can be set to about 1.1, for example.

The above dispersion may be used as it is for a predetermined purpose, or may be used as a dispersion in which another solvent is substituted according to a known method, or as a solid powder (dry powder) after solid-liquid separation or the like. You can also For the solid-liquid separation, known methods such as filtration and centrifugation can be adopted. Further, if necessary, steps such as classification, washing (washing with water, etc.) and drying can be appropriately adopted.

The metal nanoparticles (powder) obtained by the production method of the present invention may contain other components as long as the effects of the present invention are not impaired. The purity of the metal can be appropriately determined within the range of 90 to 100% by mass (particularly 95 to 100% by mass) according to the application of the metal nanoparticles, the method of use, and the like.

The features of the present invention will be described more specifically below with reference to Examples and Comparative Examples. However, the scope of the present invention is not limited to the examples.

Example 1
1 g (5.27 mmol) of tin chloride II (manufactured by Wako Pure Chemical Industries, Ltd.) as a metal ion-containing solution and 1 g of polyoxyethylene hydrogenated castor oil (HCO-60, manufactured by Nippon Surfactant Industry Co., Ltd.) which is a surfactant. And 20% hydrochloric acid (manufactured by Wako Pure Chemical Industries, Ltd.) 1.5 g dissolved in a mixed solvent of water and ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) (weight ratio of water to ethanol 1:1) 23.6 mL, as a reducing agent solution, 0.6 g of a reducing agent, sodium borohydride (manufactured by Wako Pure Chemical Industries, Ltd.) and a surfactant, polyoxyethylene hydrogenated castor oil (manufactured by Nippon Surfactant Industry Co., Ltd.) , HCO-60) was dissolved in a mixed solvent of water and ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) (water/ethanol weight ratio 1:1) to prepare a solution (11.0 mL). Next, the metal ion-containing solution was stirred with a stirrer at 200 rpm, and the reducing agent solution was dropped into the solution with a pipette to obtain metal nanoparticles dispersed in the solution.
After the obtained particles were washed 5 times and collected by centrifugation at 8000 rpm (6500, manufactured by Kubota Manufacturing Co., Ltd.), the particle size was determined by field emission scanning electron microscope (S-4800 manufactured by Hitachi High-Technologies Corporation). ), the average particle diameter was 42 nm, D10/D50 was 0.77, and D90/D50 was 1.28. An electron micrograph of the particles is shown in FIG. 2, and a particle size distribution is shown in FIG. Furthermore, as a result of analyzing the elements near the surface of the particles with an EDX analyzer (EDAX Genesis APEX2, manufactured by EDAX) attached to the microscope, tin 93.4 mass%, oxygen 4.1 mass%, carbon 2.5 mass %, and it was confirmed that the particles produced were tin.

Example 2
1 g (5.27 mmol) of tin chloride II (manufactured by Wako Pure Chemical Industries, Ltd.) as a metal ion-containing solution and polyoxyethylene hydrogenated castor oil (HCO-60, manufactured by Nippon Surfactant Industry Co., Ltd.) 0 as a surfactant 0.002 g and 0.36 g of 20% hydrochloric acid (manufactured by Wako Pure Chemical Industries, Ltd.) were dissolved in a mixed solvent of water and ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) (weight ratio of water to ethanol 1:1). As a reducing agent solution, 22.3 mL of the solution was added with 0.6 g of a reducing agent, sodium borohydride (manufactured by Wako Pure Chemical Industries, Ltd.), and a mixed solvent of water and ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) ( 11.0 mL of a solution prepared by dissolving water and ethanol in a weight ratio of 1:1) was prepared. Next, the metal ion-containing solution was stirred with a stirrer at 200 rpm, and the reducing agent solution was dropped into the solution with a pipette to obtain metal nanoparticles dispersed in the solution.
After the obtained particles were washed 5 times and collected by centrifugation at 8000 rpm (6500, manufactured by Kubota Manufacturing Co., Ltd.), the particle size was determined by field emission scanning electron microscope (S-4800 manufactured by Hitachi High-Technologies Corporation). ), the average particle diameter was 300 nm, D10/D50 was 0.59, and D90/D50 was 1.49. The particle size distribution is shown in FIG. Furthermore, the elements near the surface of the particles were analyzed by an EDX analyzer (EDAX Genesis APEX2 manufactured by EDAX) attached to the microscope, and as a result, 94.4 mass% tin, 3.8 mass% oxygen, and 1.8 mass% carbon. %, and it was confirmed that the particles produced were tin.

Example 3
1 g (5.27 mmol) of tin chloride II (manufactured by Wako Pure Chemical Industries, Ltd.) as a metal ion-containing solution and polyoxyethylene hydrogenated castor oil (HCO-60, manufactured by Nippon Surfactant Industry Co., Ltd.) 0 as a surfactant .2 g and 20% hydrochloric acid (manufactured by Wako Pure Chemical Industries, Ltd.) 1.5 g were dissolved in a mixed solvent of water and ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) (weight ratio of water to ethanol 7:3). 22.6 mL of the obtained solution was used as a reducing agent solution, and 0.6 g of a reducing agent, sodium borohydride (manufactured by Wako Pure Chemical Industries, Ltd.) and a surfactant, polyoxyethylene hydrogenated castor oil (Japan Surfactant Industry Co., Ltd. ), HCO-60) (0.1 g) was dissolved in a mixed solvent of water and ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) (water/ethanol weight ratio 7:3) to prepare a solution (10.5 mL). Next, the solution was stirred with a stirrer at 200 rpm, and the reducing agent solution was dropped into the solution with a pipette to obtain metal nanoparticles dispersed in the solution.
After the obtained particles were washed 5 times and collected by centrifugation at 8000 rpm (6500, manufactured by Kubota Manufacturing Co., Ltd.), the particle size was determined by field emission scanning electron microscope (S-4800 manufactured by Hitachi High-Technologies Corporation). ), the average particle diameter was 67 nm, D10/D50 was 0.65, and D90/D50 was 1.46. The particle size distribution is shown in FIG.

Example 4
0.8 g (4.71 mmol) of silver nitrate (manufactured by Wako Pure Chemical Industries, Ltd.) as a solution containing metal ions and 1 g of polyoxyethylene hydrogenated castor oil (manufactured by Nippon Surfactant Industry Co., Ltd., HCO-60) which is a surfactant. 22.0 mL of a solution prepared by dissolving water in a mixed solvent of water and ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) (weight ratio of water and ethanol 1:1) was used as a reducing agent solution, sodium borohydride as a reducing agent. 0.36 g (manufactured by Wako Pure Chemical Industries, Ltd.) and 1 g of polyoxyethylene hydrogenated castor oil (HCO-60, manufactured by Nippon Surfactant Industry Co., Ltd.), which is a surfactant, are added to water and ethanol (Wako Pure Chemical Industries, Ltd.). 2) was prepared by dissolving 2) in a mixed solvent of ()) (a weight ratio of water and ethanol of 1:1). Next, the metal ion-containing solution was stirred with a stirrer at 200 rpm, and the reducing agent solution was dropped into the solution with a pipette to obtain metal nanoparticles dispersed in the solution.
After the obtained particles were washed 5 times and collected by centrifugation at 8000 rpm (6500, manufactured by Kubota Manufacturing Co., Ltd.), the particle size was determined by field emission scanning electron microscope (S-4800 manufactured by Hitachi High-Technologies Corporation). ), the average particle diameter was 74 nm, D10/D50 was 0.65, and D90/D50 was 1.44. The particle size distribution is shown in FIG. Furthermore, as a result of analyzing the elements near the surface of the particle with an EDX analyzer (EDAX Genesis APEX2, manufactured by EDAX) attached to the microscope, 96.9% by mass of silver, 2.4% by mass of carbon, 0.7% by mass of oxygen %, and it was confirmed that the produced particles were silver.

Example 5
As a metal ion-containing solution, 0.1 g (0.589 mmol) of silver nitrate (manufactured by Wako Pure Chemical Industries, Ltd.) is mixed solvent of water and ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) (weight ratio of water and ethanol is 1:). A solution in which 2.5 g of polyoxyethylene hydrogenated castor oil (manufactured by Japan Surfactant Industry Co., Ltd., HCO-60), which is a surfactant, is dissolved after dissolving in 1) and further supplying ammonia gas for 1 minute with a nozzle. 54.9 mL was prepared. Further, as a reducing agent solution, 0.06 g of L-ascorbic acid (manufactured by Wako Pure Chemical Industries, Ltd.) which is a reducing agent and polyoxyethylene hydrogenated castor oil (manufactured by Japan Surfactant Industry Co., Ltd., HCO-) which is a surfactant. (60) 2.5 g was dissolved in a mixed solvent of water and ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) (weight ratio of water and ethanol: 1:1) to prepare 54.9 mL of a solution. Next, the metal ion-containing solution was stirred with a stirrer at 200 rpm, and the reducing agent solution was dropped into the solution with a pipette to obtain metal nanoparticles dispersed in the solution.
The particle diameter of the obtained particles was measured by a dynamic light scattering photometer (ELSZ-2, manufactured by Otsuka Electronics Co., Ltd.). As a result, the average particle diameter was 16 nm, D10/D50 was 0.84, and D90/D50 was 1. It was 22. The particle size distribution is shown in FIG.

Example 6
As a metal ion-containing solution, 3.5 g (20.6 mmol) of silver nitrate (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in water, and further ammonia gas was supplied for 1 minute with a nozzle, and then polyoxyethylene which was a surfactant. 10 mL of a solution in which 0.5 g of hydrogenated castor oil (manufactured by Nippon Surfactant Industry Co., Ltd., HCO-60) was dissolved was prepared. Further, as a reducing agent solution, 2 g of a reducing agent, L-ascorbic acid (manufactured by Wako Pure Chemical Industries, Ltd.) and polyoxyethylene hydrogenated castor oil (HCO-60, manufactured by Japan Surfactant Industry Co., Ltd.), which is a surfactant. 10 mL of a solution prepared by dissolving 0.5 g in water was prepared. Next, the metal ion-containing solution was stirred with a stirrer at 200 rpm, and the reducing agent solution was dropped into the solution with a pipette to obtain metal nanoparticles dispersed in the solution.
After the obtained particles were washed 5 times and collected by centrifugation at 8000 rpm (6500, manufactured by Kubota Manufacturing Co., Ltd.), the particle size was determined by field emission scanning electron microscope (S-4800 manufactured by Hitachi High-Technologies Corporation). The average particle diameter was 483 nm, D10/D50 was 0.64, and D90/D50 was 1.33. The particle size distribution is shown in FIG. Furthermore, the elements near the surface of the particle were analyzed by an EDX analyzer (EDAX Genesis APEX2 manufactured by EDAX) attached to the microscope, and as a result, silver 97.0 mass %, carbon 1.4 mass %, oxygen 0.7 mass. %, aluminum 0.5 mass %, magnesium 0.4 mass %, and it was confirmed that the produced particles were silver.

Example 7
1 g (5.27 mmol) of tin chloride II (manufactured by Wako Pure Chemical Industries, Ltd.) as a metal ion-containing solution and 0.1 g of sodium n-dodecylbenzenesulfonate (manufactured by Wako Pure Chemical Industries, Ltd.) which is a surfactant. A solution prepared by dissolving 1 g of 20% hydrochloric acid (manufactured by Wako Pure Chemical Industries, Ltd.) in a mixed solvent of water and ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) (weight ratio of water to ethanol 1:1). 1 mL of a reducing agent solution, 0.6 g of a reducing agent, sodium borohydride (manufactured by Wako Pure Chemical Industries, Ltd.) and a surfactant, sodium n-dodecylbenzenesulfonate (manufactured by Wako Pure Chemical Industries, Ltd.) ) 0.05 g was dissolved in a mixed solvent of water and ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) (weight ratio of water and ethanol 1:1) to prepare 11.0 mL of a solution. Next, the metal ion-containing solution was stirred with a stirrer at 200 rpm, and the reducing agent solution was dropped into the solution with a pipette to obtain metal nanoparticles dispersed in the solution.
After the obtained particles were washed 5 times and collected by centrifugation at 8000 rpm (6500, manufactured by Kubota Manufacturing Co., Ltd.), the particle size was determined by field emission scanning electron microscope (S-4800 manufactured by Hitachi High-Technologies Corporation). ), the average particle diameter was 188 nm, D10/D50 was 0.61, and D90/D50 was 1.40. The particle size distribution is shown in FIG. Furthermore, as a result of analyzing the elements near the surface of the particle with an EDX analyzer (EDAX Genesis APEX2 manufactured by EDAX) attached to the microscope, tin was 91.7% by mass, oxygen was 5.1% by mass, and carbon was 3.2% by mass. %, and it was confirmed that the particles produced were tin.

Example 8
0.8 g (4.71 mmol) of silver nitrate (manufactured by Wako Pure Chemical Industries, Ltd.) as a metal ion-containing solution was dissolved in water, and ammonia gas was further supplied for 1 minute with a nozzle, and then polyoxyethylene which was a surfactant. 10 mL of a solution in which 0.5 g of lauryl ether (BL-25, manufactured by Nippon Surfactant Industry Co., Ltd.) was dissolved was prepared. Further, as a reducing agent solution, 0.45 g of L-ascorbic acid (manufactured by Wako Pure Chemical Industries, Ltd.) which is a reducing agent and polyoxyethylene lauryl ether (manufactured by Japan Surfactant Industry Co., Ltd., BL-25) which is a surfactant. ) 0.25 g was dissolved in water to prepare a solution 5 mL. Next, the metal ion-containing solution was stirred with a stirrer at 200 rpm, and the reducing agent solution was dropped into the solution with a pipette to obtain metal nanoparticles dispersed in the solution.
After the obtained particles were washed 5 times and collected by centrifugation at 8000 rpm (6500, manufactured by Kubota Manufacturing Co., Ltd.), the particle size was determined by field emission scanning electron microscope (S-4800 manufactured by Hitachi High-Technologies Corporation). ), the average particle diameter was 342 nm, D10/D50 was 0.65, and D90/D50 was 1.41. The particle size distribution is shown in FIG. Furthermore, as a result of analyzing the elements near the surface of the particle with an EDX analyzer (EDAX Genesis APEX2 manufactured by EDAX) attached to the microscope, 97.0% by mass of silver, 1.1% by mass of carbon, 0.7% by mass of oxygen %, aluminum 0.7 mass %, magnesium 0.4 mass %, and it was confirmed that the produced particles were silver.

Comparative Example 1
A solution obtained by dissolving 1 g (5.27 mmol) of tin chloride II (manufactured by Wako Pure Chemical Industries, Ltd.) and 1.5 g of 20% hydrochloric acid (manufactured by Wako Pure Chemical Industries, Ltd.) in water as a solution containing metal ions. 5 mL was used as a reducing agent solution to prepare a solution 10.0 mL in which 0.6 g of a reducing agent, sodium borohydride (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in water. Next, the metal ion-containing solution was stirred with a stirrer at 200 rpm, and the reducing agent solution was added dropwise thereto with a pipette. As a result, a substantially spherical and sponge-like lump having a diameter of about 1 cm was formed.
As a result of analyzing the elements near the surface of the obtained lump by the same method as in Example 1, it was confirmed that tin was 98.5% by mass and oxygen was 1.5% by mass, and the generated lump was tin.

Claims (6)

A method for producing metal nanoparticles in a liquid phase, comprising:
For a metal ion-containing solution obtained by dissolving a surfactant containing at least one of a polyoxyethylene hydrogenated castor oil-based surfactant and a polyoxyethylene castor oil-based surfactant and a metal in an aqueous solvent containing a monohydric alcohol ,
Surfactant containing at least one selected from polyoxyethylene hydrogenated castor oil type surfactant and polyoxyethylene castor oil type surfactant and reducing agent dissolved in a mixed solvent containing water and monohydric alcohol A method for producing metal nanoparticles, comprising the step of producing metal nanoparticles by adding a solution . The manufacturing method according to claim 1, wherein the aqueous solvent contains 5% by mass or more of water and 95% by mass or less of a monohydric alcohol . The manufacturing method according to claim 1, wherein the amount of the surfactant added is 0.01 to 20% by mass in the metal ion-containing solution. The manufacturing method according to claim 1, wherein the amount of the surfactant added is 0.01 to 20% by mass in the reducing agent solution. The production method according to claim 1, wherein the metal nanoparticles produced have an average particle diameter of 10 to 500 nm. In the cumulative volume particle size distribution of the generated metal nanoparticles,
(1) The particle size corresponding to 10% by volume of the distribution is 0.5 times or more the particle size corresponding to 50% by volume of the distribution, and
(2) The production method according to claim 1, wherein the particle size corresponding to 90% by volume of the distribution is 1.5 times or less the particle size corresponding to 50% by volume of the distribution.