JPH06218273A - Fine particles carrying metal and production thereof - Google Patents

Abstract

PURPOSE:To easily procedure fine particles carrying metal uniform in metal distribution by applying metal on fine particles prepared by flocculating colloidal fine particles by an electrolysis. CONSTITUTION:A compound generating metallic ions by which a reduction process of silver nitrate and cupric chloride, etc., can be easily carried out, is added to a dispersion body of colloidal fine particles using water as a dispersion medium. This mixture is dispersed into an oily medium to prepare an emulsion and the colloidal fine particles in the emulsion are flocculated by using an electrolyte, etc., generating multivalent ions having the electric charge opposite to the charge in colloidal fine particles. Simultaneously or later they are reduced by using a reducing agent of sodium boronhydride, etc. Thus the fine particles carrying metal with uniform metal distribution are prepared simply.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to metal-supported fine particles and a method for producing the same.

[0002]

2. Description of the Related Art Fine metal particles are widely used as various catalysts when added to resins or fibers when producing conductive products such as antistatic materials and electromagnetic wave shielding materials, and conductive fibers. . Such metals include A
1, Ni, Cu, Ag, Au, Pd, etc.
From the viewpoints of lightness, dispersibility, cost, etc., these metals are used by being supported on inorganic fine particles such as mica, titanium oxide or silica. As a method for depositing a metal on the surface of the inorganic fine particles, an electroless plating method is widely used. In the electroless plating method, it is general to immerse the inorganic fine particles to be a carrier in an aqueous solution of a reducing agent and then to immerse it in an aqueous solution of a metal salt to deposit a metal on the surface of the carrier.

A vacuum vapor deposition method is also known as another method. In the vacuum vapor deposition method, carrier fine particles are set in a chamber of a vapor deposition apparatus, a vapor deposition source is placed on a tungsten basket and set in the chamber, the chamber is depressurized, and then the basket is heated to deposit a vapor deposition source metal. Deposit on a carrier. The former electroless plating method is a relatively simple method that requires no special equipment, but in order to uniformly and firmly deposit the metal on the surface of the carrier, degreasing, roughening, and cleaning the carrier. Pretreatment such as is necessary, and the manufacturing process is complicated. On the other hand, the latter vapor deposition method requires a special device and the irradiation direction of the evaporated metal is limited,
It has a drawback that it is difficult to support the metal uniformly.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing metal-supporting fine particles which is simple and has a uniform metal distribution, and metal fine particles to be obtained.

[0005]

The present inventors have completed the present invention as a result of intensive studies to solve the above-mentioned problems. That is, the present invention is: 1. Metal-supported fine particles obtained by coating fine particles obtained by aggregating colloidal fine particles with an electrolyte, and 1. In a colloidal fine particle dispersion containing a compound that generates a metal ion, the colloidal fine particles are subjected to a reduction treatment with a reducing agent at the same time as or after the aggregation of the colloidal fine particles with an electrolyte. About the manufacturing method of.

The metal-supported fine particles of the present invention can be produced, for example, by the following method. That is, a compound that generates a metal ion is added to a dispersion (hydrosol) of colloidal fine particles having water as a dispersion medium, and the compound is dispersed in an oil medium to form an emulsion. The colloidal fine particles in the emulsion are prepared. Can be obtained by adding a reducing agent at the same time as or after aggregating with an electrolyte to reduce the metal ion to a metal.

In the dispersion (hydrosol) of colloidal fine particles having water as a dispersion medium used in the present invention, the particle size of the colloidal fine particles is usually 5 to 1000 nm, preferably 10 to 500 nm. Examples of hydrosols include sols of metal oxides such as silicon oxide, zirconium oxide, aluminum oxide, iron oxide, zinc oxide, and chromium oxide, sols of metal sulfides such as arsenic sulfide, zinc sulfide, and lead sulfide, and other halogenated compounds. Examples thereof include a sol of silver, barium sulfate, ferric hydroxide, a sol of fine particles made of an organic polymer, and a sol of a mixture thereof. The inorganic sol is produced by a known method such as an aggregation method or a peptization method. The organic sol is produced, for example, by polymerizing styrene, methyl (meth) acrylate, vinyl acetate, vinyl chloride, vinylidene chloride, etc., alone or in a mixture by a known emulsion polymerization method. The solid content concentration of the hydrosol is not particularly limited, and may be within a range that facilitates the dispersion of the hydrosol in the oil medium, and is usually 5 to 50% by weight.

In the present invention, a compound capable of generating a metal ion is dissolved in the hydrosol. Examples of metal ions include silver ions, gold ions, copper ions, palladium ions,
Platinum ions, aluminum ions, nickel ions and the like can be mentioned, but not limited to these. The compound that generates a metal ion may be any compound that is water-soluble and can be easily subjected to the reduction process described later, and examples thereof include silver nitrate, tetrachloroauric acid and its alkali metal salts, cupric chloride, copper nitrate, and sulfuric acid. Examples thereof include copper, an alkali metal salt of tetrachloropalladic acid, an alkali metal salt of tetrachloroplatinic acid, hexachloroplatinic acid and its sodium salt. Alternatively, silver oxide, copper oxide, or the like may be used and dissolved in a hydrosol to be converted into a compound that generates metal ions. The concentration of the compound generating a metal ion in the hydrosol is not particularly limited as long as the colloidal fine particles are not aggregated and the dispersion is easily performed when the hydrosol is dispersed in an oil medium. Without
Usually, it is 0.001 to 50% by weight. Hereinafter, the hydrosol containing the compound that generates the metal ion is simply referred to as a metal ion-containing hydrosol.

Next, the metal ion-containing hydrosol is dispersed in an organic solvent (oil medium) containing a dispersant to obtain a W / O type dispersion. As the organic solvent used here, any solvent generally known as a hydrophobic solvent can be used. For example, aliphatic solvents include C6-C12 hydrocarbons, especially n-hexane, n-heptane, and n-octane, aromatic solvents such as benzene, toluene, xylene, and halide solvents. Chlorides are common, such as chloroform, dichloromethane, tetrachloromethane, mono- or dichlorobenzene. These solvents may be used alone or as a mixed solvent of two or more kinds. The amount of the organic solvent used is not limited as long as the resulting dispersion is a W / O type dispersion, but the proportion in the W / O type dispersion is usually 25% by volume or more, and preferably 40 to 90% by volume. It is an amount.

As the dispersant used for obtaining the dispersion, nonionic surfactants such as polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monolaurate and polyoxy are used. Ethylene sorbitan tristearate, polyoxyethylene sorbitan monostearate, sorbitan trioleate, sorbitan monooleate, sorbitan tristearate, sorbitan monostearate, sorbitan tripalmitate, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, etc. , (Hydrogenated) soybean lecithin, (hydrogenated) egg yolk lecithin, and / or polymer dispersants disclosed in JP-A-56-135501. These may be used alone or in combination of two or more. The amount of these dispersants used is preferably 0.01 to 30% by weight, more preferably 0.2 to 20% by weight, based on the metal ion-containing hydrosol.

Next, the colloidal fine particles of this dispersion are agglomerated using an electrolyte to form the carrier portion of the fine particles of the present invention. Examples of the method of performing this aggregation include a method of adding the dispersion into the aqueous electrolyte solution or a method of adding the aqueous electrolyte solution to the dispersion. The electrolyte is not particularly limited, but any electrolyte may be used as long as it does not hinder the application of the resulting fine particles and does not affect the metal reduction process.

Further, it may be the same as the compound which generates a metal ion, and examples thereof include chlorides, bromides and nitrates of alkali metals, alkaline earth metals, iron, cobalt, nickel, copper, zinc, aluminum and the like. , Sulfates, tetramethylammonium chloride, ammonium chloride, and polyelectrolytes such as polyacrylic acid, polystyrene sulfonic acid, and chitosan. In particular, it is preferable to use an electrolyte that generates polyvalent ions having a charge opposite to that of the colloidal fine particles. The amount of the electrolyte used may be an amount sufficient for agglomeration of the colloidal fine particles (as long as it is equal to or higher than the critical condensation concentration according to Schulze-Hardy's law), and 1 to 50% by weight (however, in the polymer electrolyte, 0 It is preferable to use 5 to 500% by volume of the electrolyte aqueous solution of 0.1 to 5% by weight based on the dispersion. These electrolyte aqueous solutions are hereinafter referred to as coagulants.

Next, an aqueous reducing agent solution is added to the dispersion to carry out a reduction treatment to reduce the metal ions in the metal ion-containing hydrosol to the metal. The type of reducing agent is not particularly limited as long as the reduction is easily performed, and examples thereof include sodium borohydride, citrate, hydrazine, hypophosphite, sulfite, stannous chloride, L-ascorbate, Examples thereof include tannic acid, formaldehyde, reducing sugars such as glucose, hydrogen, and the like. The amount of the reducing agent used is not particularly limited as long as it is equal to or more than the amount of the metal ion to be reduced, but it is usually 1 to 10 equivalent times, preferably 1.5 to
It is 4 equivalents. The reducing agent may be added by dissolving the reducing agent in the coagulant or by adding the coagulant and then separately. However, if the reducing agent is added after adding the aggregating agent, the metal supporting rate tends to be low, so it is preferable to add the aggregating agent and the reducing agent at the same time unless there is a particular problem (chemical reaction between the reducing agent and the aggregating agent). .

The temperature for carrying out the present invention is not particularly limited as long as it does not break the dispersion system, and it can be carried out usually at 20 to 70 ° C. The pH at the time of carrying out the present invention can be adjusted with ammonia, sodium hydroxide or the like as long as it does not affect the aggregation process, the reduction process and the like, and is usually 3 to 13.
The addition speed at which the dispersion is added into the coagulant or the coagulant is added to the dispersion is not particularly limited as long as the dispersion state is not broken. Here, the metal-supporting fine particles are obtained in the form of a slurry, and there is no particular limitation to obtain powdery metal-supporting fine particles by a conventional method. For example, it can be obtained by washing the fine particle slurry with alcohol, water and the like, performing solid-liquid separation by suction filtration, and drying. Alternatively, powdery fine particles can be directly obtained by a spray drying method or the like.

The particle size of the metal-supported fine particles obtained by the method of the present invention is determined by the dispersion conditions of the dispersion. That is, a particle having a particle size of 0.5 to 500 μm is usually obtained by selecting the type and amount of the dispersant to be used and the stirring conditions (stirring blade diameter, rotation speed, etc.). It can be adjusted according to the purpose.

The particle size of the metal-supported fine particles of the present invention is usually 0.5 to 500 μm, preferably 1 to 100 μm.
m, and the amount of the metal supported on the metal-supported fine particles of the present invention is preferably 0.002 to 60% by weight, particularly preferably 0.01 to 60% by weight based on the metal-supported fine particles of the present invention.
It is 20% by weight. According to the method of the present invention, metal-supported fine particles having a uniform metal distribution can be easily prepared.

[0017]

The present invention will be described with reference to the following examples. Example 1 Silver nitrate 2 was added to 32 ml of silica sol (Snowtex O, Nissan Chemical Co., Ltd., particle size 10 to 20 nm, concentration 20%).
96 ml of heptane in which 00 mg was dissolved and 0.06 g of soybean lecithin and 0.6 g of sorbitan monooleate were dissolved.
Was dispersed using a homogenizer (8000 rpm.,
30 seconds), a W / O type dispersion was prepared. This was placed in a 300 ml round bottom flask equipped with a stirrer and stirred at 20 wt. % Sodium nitrate aqueous solution (20 g), an aqueous solution prepared by dissolving 70 mg of sodium borohydride was added dropwise at room temperature over about 5 minutes. Stirring is continued as it is for 15 to 30 minutes at room temperature, and methanol is added to the obtained fine particle slurry in an amount of 10 to 10.
After adding 20 ml, the fine particles were filtered off by suction filtration and dried.
Fine particles carrying silver were obtained, and the average particle size was 4.
At 5 μm, the yield was 96.5% and the silver loading was 98%. (The silver supporting rate here means the ratio of the amount of silver that can be supported on the obtained fine particles to the amount of charged silver. The same applies hereinafter.)

Example 2 Silver nitrate 5 was added to 32 ml of silica sol (Snowtex O, Nissan Chemical Co., Ltd., particle size 10 to 20 nm, concentration 20%).
00 mg was dissolved and the pH was adjusted to 11.5 with ammonia, and dispersed in 96 ml of chloroform containing 0.12 g of soybean lecithin and 1.2 g of sorbitan monostearate dissolved using a homogenizer (8000 rpm., 30
Sec), and a W / O type dispersion was prepared. Take this in a 300 ml round bottom flask with a stirrer and stir for 20
wt. An aqueous solution prepared by dissolving 200 mg of formaldehyde in 30 g of a 10% aqueous sodium nitrate solution was added dropwise at room temperature over about 5 minutes. Stirring is continued for 15 to 30 minutes at room temperature and 10 to 20 ml of methanol is added to the obtained fine particle slurry.
In addition, fine particles were separated by suction filtration and dried. Fine particles carrying silver were obtained, and the average particle size was 10.2 μm.
The yield was 98.3% and the silver loading was 96%.

Example 3 Zirconium oxide sol (zirconia sol-NZS-30)
A, Nissan Chemical Co., Ltd., particle size 95 nm, concentration 35%)
500 mg of copper sulfate was dissolved in 32 ml, the pH was adjusted to 10.5 with sodium natrium hydroxide, and the mixture was dispersed in 96 ml of toluene containing 0.7 g of sorbitan monostearate and 0.07 g of polyoxyethylene sorbitan monooleate dissolved using a homogenizer. (9500 rpm., 30 seconds),
A W / O type dispersion was prepared. 30 with stirrer
Transfer to a 0 ml round bottom flask and stir 20 wt.
Aqueous solution of 700 mg of sodium L-ascorbate dissolved in 20 g of a 10% aqueous solution of sodium sulfate was added dropwise at room temperature over about 5 minutes. The liquid temperature was raised to 60 ° C., stirring was continued for 60 minutes, and methanol was added to the obtained fine particle slurry in an amount of 10 to 10.
After adding 20 ml, the fine particles were filtered off by suction filtration and dried.
Fine particles carrying copper were obtained, and the average particle size was 8.
At 4 μm, the yield was 94.2% and the copper loading was 97%.

Example 4 Zirconium oxide sol (zirconia sol-NZS-30)
A, Nissan Chemical Co., Ltd., particle size 95 nm, concentration 35%)
200 mg of copper sulfate was dissolved in 32 ml, the pH was adjusted to 10.1 with sodium sodium hydroxide, and soybean lecithin 0.06 was added.
g and 0.6 g of sorbitan monooleate were dissolved in 96 ml of heptane and dispersed using a homogenizer (150
00 rpm. , 30 seconds), and a W / O type dispersion was prepared.
This was placed in a 300 ml round bottom flask equipped with a stirrer, and 40 wt. % Aqueous solution of calcium chloride containing 30 mg of sodium borohydride dissolved therein was added dropwise at room temperature over about 5 minutes. The liquid temperature was raised to 60 ° C., stirring was continued for 60 minutes, 10 to 20 ml of methanol was added to the obtained fine particle slurry, the fine particles were separated by suction filtration and dried. Fine particles supporting copper were obtained, the average particle diameter was 3.4 μm, the yield was 98.2%, and the copper supporting rate was 98%.

Example 5 200 mg of sodium tetrachloropalladate was dissolved in 32 ml of silica sol (Snowtex O, manufactured by Nissan Kagaku Co., Ltd., particle size 10 to 20 nm, concentration 20%), soybean lecithin 0.12 g, sorbitan monostea. Rate 1.
Disperse 2 g of it in 96 ml of chloroform using a homogenizer (8000 rpm., 30 seconds) and W / O
A mold dispersion was prepared. 300 ml with a stirrer
In a round bottom flask of 10 wt. An aqueous solution in which 250 mg of stannous chloride was dissolved in 40 g of a 10% aqueous solution of sodium nitrate was added dropwise at room temperature over about 5 minutes. Stirring was continued for 15 to 30 minutes at room temperature, 10 to 20 ml of methanol was added to the obtained fine particle slurry, and the fine particles were filtered by suction filtration and dried. Fine particles supporting palladium were obtained, the average particle diameter was 5.1 μm, the yield was 98.5%, and the palladium supporting ratio was 96%.

Example 6 300 mg of potassium tetrachloroplatinate was dissolved in 32 ml of silica sol (Snowtex O, manufactured by Nissan Kagaku Co., Ltd., particle size: 10-20 nm, concentration: 20%) to obtain 0.7 g of sorbitan monostearate and poly. 96 ml of toluene in which 0.07 g of oxyethylene sorbitan monooleate was dissolved
Was dispersed using a homogenizer (8000 rpm.,
30 seconds), a W / O type dispersion was prepared. This was placed in a 300 ml round bottom flask equipped with a stirrer and stirred at 10 wt. An aqueous solution in which 350 mg of stannous chloride was dissolved in 40 g of an aqueous sodium nitrate solution of 50% was added dropwise at room temperature over about 5 minutes. Stirring is continued for 15 to 30 minutes at room temperature and 10 to 20 ml of methanol is added to the obtained fine particle slurry.
In addition, fine particles were separated by suction filtration and dried. Fine particles supporting platinum were obtained, and the average particle diameter was 6.5 μm.
The yield was 97.5% and the platinum loading was 98%.

Example 7 Copper sulfate 5 was added to 32 ml of silica sol (Snowtex O, manufactured by Nissan Kagaku KK, particle size 10 to 20 nm, concentration 20%).
Dissolve 00 mg and adjust the pH to 11.5 with sodium hydroxide.
And soybean lecithin (0.06 g) and sorbitan monooleate (0.6 g) were dissolved in 96 ml of heptane and dispersed using a homogenizer (15000 rpm., 30
Sec), and a W / O type dispersion was prepared. Take this in a 300 ml round bottom flask with a stirrer and stir for 20
wt. % Aqueous sodium nitrate solution (20 g) was added dropwise at room temperature over about 5 minutes, and stirring was continued for 15 minutes. Then, 5 wt. % Sodium L-ascorbate aqueous solution (20 g) was added dropwise at room temperature over about 5 minutes. The liquid temperature was raised to 60 ° C., stirring was continued for 60 minutes, 10 to 20 ml of methanol was added to the obtained fine particle slurry, the fine particles were separated by suction filtration and dried. Fine particles supporting copper were obtained, the average particle diameter was 6.4 μm, the yield was 97.3%, and the copper supporting rate was 85%.

Example 8 Zirconium oxide sol (zirconia sol-NZS-30)
A, Nissan Chemical Co., Ltd., particle size 95 nm, concentration 35%)
Dissolve 500 mg of silver nitrate in 32 ml and pour with ammonia.
H was adjusted to 10.5, and dispersed in 96 ml of toluene in which 0.7 g of sorbitan monostearate and 0.07 g of polyoxyethylene sorbitan monooleate were dissolved using a homogenizer (8000 rpm., 30 seconds), and W /
An O type dispersion was prepared. 300m with a stirrer
1 round bottom flask, 20 wt. % Sodium sulfate aqueous solution (20 g) was added dropwise at room temperature over about 5 minutes, and stirring was continued for 15 minutes. Then, 2 wt.
% Aqueous formaldehyde solution was added dropwise at room temperature over about 5 minutes. The liquid temperature was raised to 60 ° C., stirring was continued for 60 minutes, and 10 to 2 of methanol was added to the obtained fine particle slurry.
0 ml was added, and the fine particles were separated by suction filtration and dried. Fine particles carrying silver were obtained, and the average particle size was 5.4.
In μm, the yield was 96.8%, and the silver supporting rate was 82%.

[0025]

According to the present invention, metal-supporting fine particles having a uniform metal distribution can be easily prepared, and the metal-supporting fine particles of the present invention can be applied to conductive materials, antibacterial materials, reaction catalysts and the like. is there.

Claims (2)

[Claims] 1. Metal-supporting fine particles obtained by coating fine particles obtained by aggregating colloidal fine particles with an electrolyte, with a metal. 2. A colloidal fine particle dispersion containing a compound that generates a metal ion, wherein the colloidal fine particles are subjected to reduction treatment with a reducing agent at the same time as or after the aggregation. And a method for producing metal-supporting fine particles.