JP5216235B2 - Method for producing metal-containing fine particles - Google Patents

Description

  The present invention relates to a metal-containing fine particle and a method for producing the same, and more specifically, a diagnostic agent carrier, a bacterial separation carrier, a cell separation carrier, a nucleic acid separation / purification carrier, a protein / saccharide separation / purification carrier, an immobilized enzyme carrier, a drug delivery (hereinafter referred to as “drug delivery”). The present invention relates to a carrier, a thermotherapy material using its magnetic induction heating characteristics, a metal-containing fine particle useful as a contrast agent for MRI diagnosis using its nuclear magnetic resonance absorption characteristics, and a method for producing the same. .

  Metal-containing fine particles (for example, magnetic substance-containing fine particles) have characteristics that can be easily separated and recovered using magnetic force, and can be heated by magnetic induction. Therefore, mainly in the medical and biochemical fields, It is expected that excellent performance can be obtained as bacteria or cell separation carrier, nucleic acid / protein / saccharide separation / purification carrier, DDS carrier, enzyme reaction carrier, cell culture carrier, thermotherapy material, MRI contrast agent and the like.

  As a method for producing magnetic substance-containing fine particles, various methods for producing magnetic polymer particles using various polymerization methods are known as methods for obtaining particles of a type in which a magnetic substance is present inside the particles.

For example, by dispersing a lipophilic magnetic substance in an organic phase containing a vinyl aromatic monomer, and dispersing the dispersion homogeneously in an aqueous phase using a homogenizer, followed by suspension polymerization, Although a method for obtaining magnetic polymer particles having a relatively small particle size ( Patent Document 1 ) has been disclosed, it is inferior to the uniform dispersibility of the magnetic substance inside the particle, and the magnetic substance is localized in the vicinity of the particle surface. Is done. For this reason, there is a problem that iron ions are eluted from the magnetic polymer particles, or the magnetic substance is dissolved and flowed out under acidic conditions, and the characteristics as the magnetic polymer particles are impaired.

In addition, an iron compound is precipitated as a hydroxide in the presence of a porous polymer particle having a specific functional group, and this iron compound is oxidized to introduce a magnetic substance into the porous polymer particle. Although a method of obtaining magnetic polymer particles having a large particle size and a uniform diameter is disclosed ( Patent Document 2 ), the manufacturing process of the magnetic polymer particles is complicated, and the magnetic material is not encapsulated by the polymer. There is a problem that iron ions are eluted.

  As described above, since the magnetic polymer particles obtained by the conventional synthesis method have a problem of elution of iron ions to the outside, they can be applied only to applications and fields that are not affected by elution of iron ions. is the current situation. For this reason, it is desired to develop new magnetic particles that are excellent in dispersibility of magnetic materials and do not elute iron ions and the like.

From a practical point of view, it is necessary that the magnetic particles are difficult to settle in an aqueous medium and maintain a homogeneous dispersion state.
Japanese Patent Publication No. 4-3088 Japanese Patent Publication No. 5-10808

  An object of the present invention is to provide metal-containing fine particles in which a metal component (for example, a magnetic component) is difficult to elute, polymer fine particles useful for producing the metal-containing fine particles, or a method for producing them.

In view of the above problems, the present inventors have completed the present invention as a result of intensive studies. The present invention has one or more of the following features.
(1) One feature of the present invention is that (a) a step of performing an emulsion polymerization reaction using a polymerizable monomer containing 1% or more of an acrylic ester compound and an emulsifier, and (b) a pre-emulsion polymerization reaction step. (C) a step of hydrolyzing the ester bond of the acrylic ester compound in the polymer fine particles obtained in a predetermined pH range and a predetermined temperature range; and (c) the polymer fine particles obtained in the hydrolysis step and bivalent or higher A step of performing ion exchange between a carboxyl group contained in the polymer fine particles and a metal ion in the metal salt by mixing with a metal salt under a predetermined pH range, and (d) obtained by the ion exchange step A method for producing metal-containing fine particles comprising the steps of carbonizing polymer fine particles at 300 ° C. or higher to obtain a carbonized structure in which the metal fine particles are dispersed and supported. .
(2) In a preferred embodiment, the metal-containing fine particles have a volume average diameter of 50 nm to 500 nm.
(3) In a preferred embodiment, the volume average diameter of the metal fine particles dispersed in the carbonized structure is 50 nm or less.
(4) In a preferred embodiment, the emulsifier used in the emulsion polymerization reaction is a sulfonic acid surfactant.
(5) In a preferred embodiment, the predetermined pH range of the step (b) is 8-14.
(6) In a preferred embodiment, the predetermined temperature range of the step (b) is 5 to 120 ° C.
(7) In a preferred embodiment, the predetermined pH range of the step (c) is 7-10.
(8) to (11) In a preferred embodiment, the divalent or higher metal salt is a cobalt salt, a nickel salt, an iron salt, or a mixture of two or more selected from a cobalt salt, a nickel salt, and an iron salt. It is.
(12) In a preferred embodiment, the concentration of the mixed divalent or higher metal salt is less than or equal to the limit aggregation concentration of the polymer fine particles with respect to water in the mixed solution.

  Other features of the present invention including the above features and their effects will become apparent from the following embodiments and drawings.

  According to the present invention, metal-containing microparticles (for example, magnetic-substance-containing microparticles) that are not affected by the characteristics of the raw metal and are difficult to elute the metal component can be obtained. Application as nucleic acid separation and purification carrier, protein / saccharide separation and purification carrier, immobilized enzyme carrier, DDS carrier, thermotherapy material, MRI contrast agent and the like can be expected.

  Embodiments of the metal-containing fine particles, polymer fine particles useful for producing the metal-containing fine particles, and methods for producing them are described below.

1. Metal-containing fine particles The metal-containing fine particles of the present invention have a form in which metal fine particles are dispersed in carbonized structure fine particles.

  The carbonized structure refers to a structure obtained by carbonization treatment using an organic material as a starting material. Carbonization treatment is the heat treatment of organic matter to cause the cleavage of carbon-carbon bonds or the decomposition of carbon-hydrogen bonds in the internal structure of organic matter. This refers to the process of forming a macromolecule (carbon structure) by polycondensation. The treatment temperature greatly depends on the structure and properties of the organic substance (solid, liquid, etc.) or the presence or absence of water or oxygen. With regard to the behavior during decomposition, it is possible to grasp the appropriate processing temperature from the weight change using various thermobalance analyzers, and here, excluding the moisture of the original organic matter when analyzed with the thermobalance analyzer A structure that has been processed at a temperature equal to or higher than 50% by weight is referred to as a carbonized structure.

  Conventionally, there have been technologies for including metals and the like in resins, etc., but in all cases, the size and magnetic properties of the metal fine particles after inclusion depend on the magnetic material, and it is difficult to suppress elution of the magnetic material. There were restrictions. In this respect, in the present invention, as described above, (1) fine polymer particles are formed by emulsion polymerization using a monomer having an ester bond, and (2) the ester bond of the generated polymer particles is hydrolyzed. (3) ion exchange of carboxyl groups in the generated polymer fine particles to appropriately fix desired ions in the particles, and It has a plurality of features that are not available in the prior art, such as carbonization treatment while being dispersed in (4), and inclusion of metal fine particles in a carbonized structure. Feature (1) produces fine particles with an average diameter that could not be achieved with the prior art. Although ion-exchangeable fine particles can be prepared by using an acrylic acid monomer instead of a monomer having an ester bond, by using a monomer having an ester bond, The amount of ion exchange groups (carboxyl groups) in the exchangeable polymer fine particles can be adjusted and can be obtained in high yield. The feature (3) makes it possible to generate fine particles having a desired metal composition. According to the feature (4), the metal fine particles are sintered (blocked) and fixed in the carbonized structure derived from the polymer. Therefore, according to the embodiment of the present invention, it is possible to produce metal-containing fine particles in a high yield without being influenced by the characteristics of the metal, and the obtained metal-containing fine particles can be retained without almost eluting the metal component. An unprecedented effect is achieved.

2. Production Method The production method of the metal-containing fine particles of the present invention is not particularly limited, and can be obtained, for example, by the following method.

2-1. Preparation of polymer fine particles (polymer latex) First, polymer fine particles (polymer latex) are prepared using a polymerizable monomer containing 1% or more of an acrylic ester as a raw material. At this time, the polymerization method is most suitable for producing fine particles having a target particle size of 50 nm or more and 500 nm or less by emulsion polymerization. The volume average diameter can be measured, for example, using a general dynamic light scattering apparatus such as “Microtrack UPA” manufactured by Honeywell. The volume average diameter (MV [μm]) refers to an average diameter weighted by volume, and is an average diameter generally defined by Equation (1).
MV = Σ (V _i · d _i ) / Σ (V _i ) Equation (1)
V _i [(μm) ³ ]: Volume of particle i (i = 1, 2,..., N)
d _i [μm]: diameter of the particle i (i = 1, 2,..., N)
The acrylic ester compound is preferably 1% or more and 100% or less of the entire monomer. If it is less than 1%, sufficient ion exchange is not performed through the subsequent hydrolysis treatment and ion exchange treatment, and metal fine particles may not be formed in the subsequent carbonization treatment.

  The concept of “polymerizable monomer” includes both a monomer or a monomer and a crosslinking agent suitable for the polymerization of that monomer. As the polymerizable monomer to be used, a vinyl monomer (crosslinking agent) can be appropriately used in addition to 1% or more of the acrylic acid ester compound.

Examples of acrylic ester compounds include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, and t-butyl (meth). Acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, etc. These may be used alone or in combination of two or more, and methyl methacrylate and ethyl methacrylate are particularly preferred from the standpoint of availability and production cost.
Examples of the vinyl monomer include aromatic vinyl compounds such as styrene, α-methylstyrene, o-vinyltoluene, m-vinyltoluene, p-vinyltoluene and divinylbenzene; unsaturated carboxylic acids such as crotonic acid; (meth) acrylonitrile And vinyl cyanide compounds such as vinylidene cyanide; vinyl halide compounds such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, and tetrafluoroethylene; acrylic acid and methacrylic acid. These may be used alone or in combination of two or more.

As the polymerization initiator used when carrying out the above emulsion polymerization, water-soluble or oil-soluble polymerization initiators, thermal decomposition type or redox type polymerization initiators, etc. are used, for example, ordinary initiators such as persulfates, Alternatively, an organic peroxide, an azo compound, or the like may be used alone, or the compound may be used in a redox system by combining sulfite, hydrogen sulfite, thiosulfate, first metal salt, sodium formaldehyde sulfoxylate, and the like. Preferred examples of the persulfate as the polymerization initiator include sodium persulfate, potassium persulfate, and ammonium persulfate. Preferred examples of the organic peroxide include t-butyl hydroperoxide, cumene hydroperoxide, and benzoyl peroxide. And lauroyl peroxide.
These polymerization initiators are generally used in the range of usually 0.1 to 5 parts by mass with respect to 100 parts by mass of the polymerizable monomer, and the amount of hydrophilic polymerizable monomer used during polymerization and the use thereof The particle diameter of the polymer particles to be prepared can be controlled by appropriately setting the type and amount of the polymerization initiator.

  Known emulsifiers (surfactants or emulsion polymerization agents) are used. For example, anionic surfactants such as fatty acid salts, alkyl sulfate esters, alkylbenzene sulfonates, alkyl phosphate esters, sulfosuccinic acid diester salts, and nonionic interfaces such as polyoxyethylene alkyl ethers and polyoxyethylene fatty acid esters Examples include activators. These may be used alone or in combination of two or more. Among them, sulfonic acid surfactants such as sodium α-olefin sulfonate, alkyl sulfate ester salt, alkylbenzene sulfonate salt, alkyl phosphate ester salt, sulfosuccinic acid diester salt (for example, sulfonic acid anionic surfactant) This is preferable because the treatment with the stability of the polymer latex maintained is easy during ion exchange.

  The temperature and time during the polymerization reaction are not particularly limited, and may be appropriately adjusted according to the purpose of use so as to obtain a desired weight average molecular weight.

  The pH during the polymerization reaction is not particularly limited, and may be appropriately adjusted depending on the monomers and surfactants used.

2-2. Ester hydrolysis reaction in polymer latex A carboxyl group is produced by hydrolysis treatment of an ester bond contained in the polymer latex obtained by the above polymerization method in alkaline water. At this time, the treatment pH is preferably 8 to 14 from the viewpoint of the productivity of the hydrolysis treatment. Moreover, it is preferable to perform processing temperature at 50-120 degreeC from a viewpoint of the production cost concerning processing, and stability of latex.

  At this time, the hydrolysis reaction rate is determined by the pH titration of the polymer with hydrochloric acid, and the titration (number of titration moles) between two inflection points derived from the carboxyl group is the amount of ester contained therein (mol of ester compound). It can be calculated by dividing by (number). An example of pH titration is shown in FIG. From the titration results shown in FIG. 1, since the number of moles of hydrochloric acid used between the inflection points of the titration with respect to the number of moles of the ester compound is 0.5, the reaction rate is calculated to be 50%.

  The hydrolysis reaction rate is preferably 1% or more and 100% or less because ion exchange is performed throughout the polymer fine particles in the subsequent ion exchange treatment.

2-3. Mixing polymer latex and metal salt aqueous solution (ion exchange)
2-2. Ion exchange is carried out by mixing the polymer latex obtained by the above treatments with a metal salt aqueous solution. At this time, the metal salt aqueous solution is not particularly limited, but a divalent or higher metal salt is preferable for forming metal fine particles.

  Although it does not specifically limit as metal salt more than bivalence, Cobalt salts, such as cobalt nitrate, cobalt sulfate, cobalt chloride; Nickel salts, such as nickel nitrate, nickel sulfate, nickel chloride; Copper nitrate, copper sulfate, copper chloride, etc. Copper salts; Iron salts such as iron nitrate, iron sulfate, and iron chloride; Aluminum salts such as aluminum nitrate, aluminum sulfate, and aluminum chloride; Magnesium salts such as magnesium nitrate, magnesium sulfate, and magnesium chloride; Silver nitrate, silver chloride, silver sulfate, etc. Among these, cobalt salts, nickel salts, and iron salts are preferable for expressing the generated metal fine particles as a magnetic substance.

The concentration of the aqueous metal salt solution is not particularly limited, but it is preferable to use a concentration not higher than the limit aggregation concentration of the polymer latex because the subsequent carbonization treatment can be performed while the polymer latex is dispersed in water.
The critical coagulation concentration of polymer latex is “Dispersion and Emulsion Chemistry”, Fumio Kitahara and Kunio Furusawa, Engineering Books, p. 113 (1991) and the like, the dispersion state produced by the electrostatic repulsive force of the polymer latex corresponds to the critical concentration at which the polymer latex is destroyed by the salt. If it is below this critical concentration, it is preferable because the amount of the polymer latex that remains dispersed in water by the end of the carbonization treatment described later is large.
As a method for measuring the limit coagulation concentration, “Dispersion and Emulsion Chemistry”, Fumio Kitahara and Kunio Furusawa, Engineering Books, p. 129 (1991), there is a method in which aqueous solutions prepared with various metal salt concentrations are prepared, and a polymer latex is dropped onto the solution to measure the light transmittance. As another method for measuring the limit aggregation concentration, there is a method in which aqueous solutions prepared at various metal salt concentrations are prepared, and a polymer latex is dropped on the solution to visually check whether aggregates are formed.

  The amount of the metal salt in the metal salt aqueous solution mixed with the polymer latex is 0.001 to 2 equivalents with respect to the total amount of carboxyl groups contained in the polymer latex. It is preferable to form, and more preferably 0.01 to 1 equivalent.

  The pH when the polymer latex is mixed with the metal salt aqueous solution is not limited to this, but the carboxyl group derived from acrylic acid, methacrylic acid or other monomer in the polymer latex and the metal ion in the metal salt. In order to generate a magnetic substance, it is preferable that the ion exchange be performed in an effective range. Specifically, pH 3-11 is preferable, and pH 7-10 is more preferable. If pH is 7-10, ion exchange will be performed efficiently and it will become easy to disperse | distribute a metal as a fine particle. In preferred embodiments, the pH is between 7 and 9, or between pH 7.5 and 8.5, or about pH 8.

  The obtained polymer latex can be used as an ion exchange resin or the like for recovering salts as impurities in water, in addition to the case of forming metal-containing fine particles by carbonization treatment described later.

2-4. Carbonization treatment An aqueous solution (hereinafter referred to as “polymer-containing aqueous solution”) in which a polymer latex is mixed with a metal salt aqueous solution to perform an ion exchange treatment between a carboxyl group in the polymer latex and a metal ion in the metal salt, Subsequently, it can be carbonized by carbonization treatment.

  As described above, the temperature of the carbonization treatment is set to be equal to or higher than the temperature at which the weight is 50% or less with respect to the weight excluding the moisture of the original organic matter when analyzed with a thermobalance analyzer. Here, the polymer mainly composed of a normal acrylic monomer is not particularly limited, but is preferably from 300 ° C. to less than 1500 ° C. from the viewpoint of the temperature range necessary for thermal decomposition and productivity. If it is less than 300 degreeC, carbonization will not fully advance. On the other hand, if the temperature is 1500 ° C. or higher, the internal pressure during the hydrothermal treatment increases sharply, and there is a risk of unnecessarily high pressure treatment.

  If necessary, water can be added to the polymer-containing aqueous solution before the carbonization treatment. At this time, the amount of water is preferably added so that the concentration of the polymer in the polymer-containing aqueous solution is 0.0001% or more and less than 50% from the viewpoint of ease of handling and the yield of fine particles. If the amount is less than 0.0001%, the amount of the aqueous solution to be treated is enormous compared to the required amount, which is not efficient. If the amount is 50% or more, the distance between the polymer fine particles is small, and thus there is a possibility of aggregation during the carbonization treatment.

  Although it does not specifically limit as a carbonization processing apparatus, A general pressure-resistant stirring tank or a pressure-resistant container can be used. Examples of the heating medium include, but are not limited to, a heating method using a jacket or an internal coil, and a method of putting a pressure vessel into a heat medium such as a sand bath.

  The volume average diameter of the metal fine particles (corresponding to “metal fine particles dispersed in the carbonized structure”) generated by the carbonization treatment is preferably 50 nm or less in view of the effect as a magnetic substance. If it is 50 nm or more, there is a risk that the magnetic susceptibility and the uniformity of the magnetization amount of the included metal fine particles may be impaired.

2-5. Application example of metal-containing fine particles The aqueous solution obtained as described above is obtained as a dispersion of metal-containing fine particles in water. It is expected to be used as a cell separation carrier, nucleic acid separation / purification carrier, protein / saccharide separation / purification carrier, immobilized enzyme carrier, DDS carrier, thermotherapy material, MRI contrast agent and the like.
The metal-containing fine particles dispersed in water can be diluted or concentrated with water depending on the application. Although it does not specifically limit as a dilution method, The method of mixing metal-containing fine particle aqueous solution and water with a stirring tank is common. The concentration method is not limited, and a method of volatilizing water by heating in a stirring tank, a steam stripping treatment, a concentration device such as an evaporator, or the like can be used.

Various measurement methods used in the examples are as follows.

(Measurement of limit aggregation concentration)
In the examples, the limit aggregation concentration was measured by the following method. As described above, the critical aggregation concentration is a critical concentration at which the dispersion state produced by the electrostatic repulsion force of the polymer latex is destroyed by the salt, and abrupt aggregation occurs at a concentration higher than that concentration. The limiting aggregation concentration can be measured by, for example, absorbance, and can be sufficiently confirmed by visual observation because it is sufficient to confirm the presence or absence of aggregation.
First, an aqueous solution of each concentration is prepared using an inorganic salt to be ion-exchanged (that is, an aqueous metal salt solution that performs an ion exchange treatment between a carboxyl group in the polymer latex and a metal ion in the metal salt). In this example, 50 ml of an aqueous solution adjusted to various concentrations is prepared in a 50 ml centrifuge tube (manufactured by AS ONE: screw mouth centrifuge tube), and 2 ml of acrylic acid polymer latex is added thereto and stirred. Thereafter, the mixture is allowed to stand for 1 hour at room temperature under atmospheric pressure and the presence or absence of aggregates is observed. The minimum concentration at which aggregation occurs was defined as the limit aggregation concentration.
(TEM observation)
In the examples, a transmission electron microscope JEM-1011 manufactured by JEOL Ltd. was used for TEM (Transmission Electron Microscope) observation.

(PH measurement)
The pH in the examples refers to a value measured by a Japanese Industrial Standard pH measurement method (JIS Z 8802 1984). The measured value of pH is obtained by placing a collected sample in a container such as a beaker. A value measured by confirming that the sample temperature has reached 25 ° C. in a water bath or the like kept at 0 ° C. For measurement, D-51S manufactured by Horiba Ltd. was used.

Example 1
(1) Production of Polymer Fine Particles (Polymer Latex) Specific examples of the present invention will be described below in more detail with reference to examples, but these do not limit the present invention.
Add 1250 ml of distilled water to a separable flask containing 4 baffle plates (manufactured by ASONE: 2000 ml cylinder, 120 mm inner diameter, 130 mm body diameter, 230 mm height), and add 4.8 g sodium dodecylbenzenesulfonate as an emulsifier did. Further, 480 g of methyl methacrylate monomer was added.
The pH of the above solution was adjusted to 12 using an aqueous sodium hydroxide solution.
The separable flask was sealed and warmed in a constant temperature water bath set at 70 ° C. In order to remove oxygen in the reactor, the inflow of nitrogen was started at the same time, the number of stirring was set to 800 rpm, and stirring was started. Six paddle blades (inner diameter: 50 mm) were used as the stirring blades.
After 1 hour, ensure that the temperature of the separable flask has reached 70 ° C., it was added to start polymerization potassium persulfate 0.144g of polymerization initiator.
After 4 hours, when the polymerization was almost completed, the stirring was stopped, the supply of nitrogen gas was stopped, and the polymer latex (A) (hereinafter, the elements obtained in the production process were appropriately represented by symbols such as A, B, C, D, etc. (Represented by).

(2) Hydrolysis of polymer latex The polymer latex recovered in (1) above was mixed with a 1N aqueous sodium hydroxide solution to adjust the pH of the latex to 10.5 and heated to 30 ° C for 10 hours with a stirrer. Stir to react. At this time, since the pH decreased with the progress of hydrolysis, the pH was kept constant at 10.5 with a 1N aqueous sodium hydroxide solution while monitoring the pH. As a result, a hydrolyzed polymer latex (B) was obtained. The hydrolysis reaction rate of this hydrolysis latex (B) was 46%.

(3) Mixing of polymer latex and metal salt aqueous solution (ion exchange)
When the limiting aggregation concentration of the hydrolyzed polymer latex (B) recovered in the above (2) was measured and found to be 7.0 mmol / L, a 6.0 mmol / L cobalt nitrate aqueous solution was prepared. 1 ml of the hydrolyzed polymer latex (B) was added to 230 ml of the aqueous solution to ion exchange the carboxyl groups in the polymer fine particles. At this time, in order to sufficiently advance ion exchange, sodium hydroxide was added to adjust the pH to 8.2. This obtained the aqueous solution (C).

(3) Carbonization treatment 2 ml of the ion exchange treated aqueous solution (C) was placed in a pressure resistant heat resistant reactor 2 (capacity 6 ml) of the carbonization apparatus shown in FIG. As the carbonization apparatus, an apparatus well known to those skilled in the art may be used. The carbonization apparatus shown in FIG. 2 includes a pressure gauge 4, a purge valve 6, and a nitrogen cylinder 8 as an example. The reactor 2 was attached, and by operating the nitrogen cylinder 8 and the purge valve 6, pressurization (0.3 MPaG) and purging with nitrogen gas were repeated 30 times to remove oxygen inside the reactor 1.

  The fluidized sand bath shown in Fig. 3 was preheated to 300 ° C. A fluid sand bath may use an apparatus well known to those skilled in the art. The flowing sand bath 10 of FIG. 3 includes, as an example, a pressure resistant and heat resistant reactor 12, a pressure gauge 14, a purge valve 16, a compressor 18, and a temperature controller 20. The prepared reactor 12 is put into the sand bath 10 and the sand bath 10 is heated to 500 ° C. at a temperature rising rate of 10 ° C./min. When the inside of the reactor 12 reaches 500 ° C., heating is continued for 30 minutes, and the whole reactor 12 is cooled with water.

  When the reactor was sufficiently cooled, the aqueous solution was taken out from the reactor to obtain the desired aqueous solution (D) of fine particles (metal-containing fine particles).

(4) Observation of metal-containing fine particles When the obtained aqueous solution (D) was transferred to a 100 ml beaker and stirred with a stirrer without a stirrer, it was confirmed that the aqueous solution (D) was stirred.

  Further, when this aqueous solution (D) was dried and observed by TEM, cobalt particles (metal fine particles) dispersed in the carbonized structure fine particles were observed as shown in FIG. At this time, the particle size of the carbonized fine particles in FIG. 4 was about 200 nm, and the particle size of the cobalt particles in the carbonized structure fine particles was about 10 nm. As shown in FIG. 4, according to the present embodiment, fine particles having a metal composition with an extremely small average diameter that could not be achieved by the prior art were generated, and the fine metal particles were sintered (blocked). It was possible to create metal-containing fine particles containing carbon in the carbonized material.

FIG. 1 is a titration curve when HCl titration is performed to calculate the hydrolysis reaction rate. FIG. 2 is an explanatory diagram of a pressure- and heat-resistant reactor for hydrothermal carbonization treatment used in the examples of the present invention. FIG. 3 is an explanatory diagram of a fluidized sand bath used in an embodiment of the present invention. FIG. 4 is a photograph of the TEM observation of the magnetic substance-containing fine particles obtained in the example of the present invention.

Explanation of symbols

2 Pressure-resistant and heat-resistant reactor 4 Pressure gauge 6 Purge valve 8 Nitrogen cylinder 10 Flowing sand bath 12 Pressure-resistant and heat-resistant reactor 14 Pressure gauge 16 Purge valve 18 Compressor 20 Temperature controller

Claims (10)

(A) performing an emulsion polymerization reaction using a polymerizable monomer containing 1% or more of an acrylic acid ester compound and an emulsifier,
(B) pre-Symbol emulsion polymerization reaction step of hydrolyzing the ester bonds of the acrylic ester compound of the polymer microparticles obtained in step under predetermined pH range and a predetermined temperature range,
(C) By mixing the polymer fine particles obtained in the hydrolysis step and a metal salt having a valence of 2 or more under a predetermined pH range, the carboxyl groups contained in the polymer fine particles and the metal ions in the metal salt A process of performing ion exchange of
(D) a step of obtaining a carbonized structure in which the metal fine particles are dispersed and supported by carbonizing the polymer fine particles obtained by the ion exchange step at 300 ° C. or higher;
The manufacturing method of the metal containing fine particle containing each process of these. The method for producing metal-containing fine particles according to claim 1 , wherein the emulsifier used in the emulsion polymerization reaction is a sulfonic acid surfactant. The said manufacturing method of Claim 1 or 2 whose predetermined | prescribed pH range of the said process (b) is 8-14. The said manufacturing method of any one of Claims 1-3 whose predetermined temperature range of the said process (b) is 5-120 degreeC. The said manufacturing method of any one of Claims 1-4 whose predetermined | prescribed pH range of the said process (c) is 7-10. The said manufacturing method of any one of Claims 1-5 whose metal salt more than bivalence is a cobalt salt. The said manufacturing method of any one of Claims 1-5 whose metal salt more than bivalence is a nickel salt. The said manufacturing method of any one of Claims 1-5 characterized by the metal salt more than bivalence being an iron salt. The said manufacturing method of any one of Claims 1-5 which consists of 2 or more types of mixtures chosen from cobalt salt, nickel salt, and iron salt. The concentration according to claim 1 , wherein the concentration of the mixed divalent or higher metal salt is equal to or less than a limit aggregation concentration of the polymer fine particles with respect to water in the mixed solution. Production method.