JP3680916B2 - Method for producing metal-coated powder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a metal-coated powder suitable for use as a filler, antibacterial agent, etc. having good electrical conductivity, catalytic ability, heat resistance, etc. The present invention relates to a method for producing a metal-coated powder that can be obtained by an inexpensive and simple process.
[0002]
[Prior art and problems to be solved by the invention]
Metal-coated powders produced by coating powders, especially non-conductive powders with various metals, have a high degree of freedom in selecting materials to be used as base fillers. Since various applications such as a coating agent and a coating agent can be expected, various manufacturing methods have been studied, and in particular, a method using an electroless plating method has been put into practical use.
[0003]
However, the electroless plating method has a problem in the adhesion between the plating metal and the powder, and a silane coupling agent (for example, γ-aminopropyl) is used to produce a powder having a metal film with better adhesion. A method using a silane monomer such as triethoxysilane (JP 61-257479 A, JP 62-297471 A), a method using a palladium colloid sol using a reducing agent such as NaBH ₄ ( Japanese Patent Laid-Open No. 63-79975), a method of etching the powder surface, and the like have been proposed. However, these methods have not always obtained good metal-coated powders.
[0004]
The present invention has been made in view of the above circumstances, and is provided with a metal coating capable of exhibiting excellent characteristics such as electrical characteristics, catalytic performance, and heat resistance with good adhesion, and has a conductive and catalytic ability filler, antibacterial An object of the present invention is to provide a method for producing a metal-coated powder, which can obtain a metal-coated powder suitable as an agent or the like by an inexpensive and simple process.
[0005]
Means for Solving the Problem and Embodiment of the Invention
As a result of intensive studies to achieve the above object, the present inventor treated the powder with a silicon-based polymer compound having a Si—Si bond in a molecule dissolved in an organic solvent, and the surface of the powder was silicon-based. After the step of coating with a film made of a polymer compound, the powder coated with the film made of a silicon-based polymer compound in this first step contains a metal salt in the presence or absence of a surfactant. After processing with a solution and forming a metal film by supporting a metal on the surface of the film made of the silicon-based polymer compound, the metal film is treated with an electroless plating solution in the presence of a surfactant. By performing the second step of forming the coating film, the powder surface is coated with a coating film made of a silicon-based polymer compound having a Si-Si bond in the molecule, and the coating surface is coated with an inexpensive and simple process. Metal is supported and metal coating Made metal-coated powder obtained was found that this metal coating which was firmly adhered to the conductive or filler having catalytic ability, it is widely available as an antimicrobial agent.
[0006]
In this case, the silicon-based polymer compound is a very interesting polymer because of its metallic properties, electron delocalization, high heat resistance and flexibility, and good thin film formation characteristics compared to carbon. A polysiloxane having a hydrogen atom directly bonded to a silicon atom is known as a polymer compound having reducibility and is used in various applications. Furthermore, it is well known that polysilane is used as a precursor of silicon carbide ceramic material, and polysiloxane is used as a precursor of silicon oxide ceramic material.
[0007]
When the present applicant contacts a powder whose surface is treated with a silicon-based polymer compound having such a reducing action with a solution containing metal ions, a metal colloid is generated and retained on the powder surface. Has been proposed in Japanese Patent Application No. 10-121836 (Japanese Patent Application Laid-Open No. 11-306855) , and this method is a silicon-based polymer compound. Since the surface-treated powder becomes hydrophobic at the time of manufacture, if the powder cannot be sufficiently brought into contact with a solution containing metal ions, a part of the powder may not be covered with metal.
[0008]
Therefore, the present inventor conducted further research on the production technology of the metal-coated powder using the silicon-based polymer compound, and in producing the metal-coated powder using the silicon-based polymer compound-coated powder, Coating is performed by electroless plating in the presence of a surfactant after forming a colloidal catalyst by dispersing silicon-based polymer compound-coated powder in a solution containing a metal salt in the presence or absence of an agent. The present inventors have found that a metal-coated powder that is well coated with metal without unevenness can be easily and efficiently produced at low cost, and has led to the present invention.
[0009]
Therefore, the present invention
(1) A powder is treated with a silicon-based polymer compound having a Si—Si bond in a molecule represented by the following general formula (1) in which the powder is dissolved in an organic solvent, and the powder surface is treated with the silicon-based polymer compound. A step of coating with a coating,
(R ¹ _m R ² _n X _p Si) _q (1)
Wherein R ¹ and R ² are each a hydrogen atom, a substituted or unsubstituted monovalent hydrocarbon group, X is the same group as R ¹ , an alkoxy group, a halogen atom, an oxygen atom or a nitrogen atom. 0.1 ≦ m ≦ 1, n is 0.1 ≦ n ≦ 1, p is 0 ≦ p ≦ 0.5, and 1 ≦ m + n + p ≦ 2.5, q is 10 ≦ q ≦ 100 , An integer of 1,000.)
(2) The powder coated with the coating made of the silicon-based polymer compound in the first step is treated with a solution containing a metal salt in the presence or absence of a surfactant, and the silicon-based polymer compound Forming a metal film by supporting a metal on the surface of the film, and then treating with an electroless plating solution in the presence of a surfactant to form a film from the electroless plating solution. A method for producing a metal-coated powder is provided.
[0010]
Hereinafter, the present invention will be described in more detail. The first step of the method for producing a metal-coated powder according to the present invention is a silicon-based polymer compound having a Si—Si bond in a molecule obtained by dissolving the powder in an organic solvent. And the powder surface is coated with a film made of a silicon-based polymer.
[0011]
Examples of the powder used in the present invention include insulating powders such as silica, alumina, and alumina silicate, semiconductive powders such as titanium oxide and zinc oxide, and conductive powders such as carbon and aluminum. Can be mentioned. The shape is not particularly limited, and various shapes such as a powder shape, a fiber shape, and a flake shape can be used.
[0012]
In the present invention, a silicon polymer compound having a Si—Si bond in the molecule is used as the silicon polymer compound having a reducing action.
[0013]
Here, as the silicon-based polymer compound having a Si—Si bond in the molecule, polysilane is preferably used, and polysilane represented by the following general formula (1) is preferable.
[0014]
(R ¹ _m R ² _n X _p Si) _q (1)
In the above formula (1), R ¹ and R ² are each a hydrogen atom, a substituted or unsubstituted monovalent hydrocarbon group, and R ¹ and R ² may be the same or different from each other, As the monovalent hydrocarbon group, an aliphatic, alicyclic or aromatic monovalent hydrocarbon group is used. As the aliphatic or alicyclic monovalent hydrocarbon group, those having 1 to 12 carbon atoms, particularly 1 to 6 carbon atoms are preferable. For example, alkyl groups such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. And cycloalkyl groups such as a group, a cyclopentyl group, and a cyclohexyl group. As the aromatic monovalent hydrocarbon group, those having 6 to 14 carbon atoms, particularly 6 to 10 carbon atoms are suitable, and examples thereof include a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and a benzyl group. In addition, as the substituted monovalent hydrocarbon group, one or all of the hydrogen atoms of the unsubstituted monovalent hydrocarbon group exemplified above are substituted with a halogen atom, an alkoxy group, an amino group, an aminoalkyl group, etc. For example, a monofluoromethyl group, a trifluoromethyl group, an m-dimethylaminophenyl group and the like can be mentioned.
[0015]
X is the same group as R ¹ , an alkoxy group, a halogen atom, an oxygen atom or a nitrogen atom, and the alkoxy group preferably has 1 to 4 carbon atoms such as a methoxy group, an ethoxy group, an isopropoxy group, etc. Examples of the halogen atom include a fluorine atom, a chlorine atom and a bromine atom. Of these, a methoxy group and an ethoxy group are preferably used as X.
[0016]
m is 0.1 ≦ m ≦ 1, preferably 0.5 ≦ m ≦ 1, n is 0.1 ≦ n ≦ 1, preferably 0.5 ≦ n ≦ 1, p is 0 ≦ p ≦ 0.5, Preferably, 0 ≦ p ≦ 0.2 and 1 ≦ m + n + p ≦ 2.5, preferably 1.5 ≦ m + n + p ≦ 2, and q is 10 ≦ q ≦ 100,000, preferably 10 It is an integer in the range of ≦ q ≦ 10,000.
[0020]
In this step, examples of the organic solvent for dissolving the silicon polymer compound include aromatic hydrocarbon solvents such as benzene, toluene, and xylene, aliphatic hydrocarbon solvents such as hexane, octane, and cyclohexane, tetrahydrofuran, and dibutyl ether. An aprotic polar solvent such as ether solvents such as ethyl acetate, esters such as ethyl acetate, dimethylformamide, dimethyl sulfoxide and hexamethylphosphoric triamide, nitromethane, acetonitrile and the like are preferably used.
[0021]
The concentration of the silicon-based polymer compound-containing solution is preferably 0.01 to 50% (% by weight, the same applies hereinafter), particularly 1 to 20%. A concentration of less than 0.01% is sufficient to cause a plating reaction. In some cases, a metal colloid cannot be formed on the powder surface. If it exceeds 50%, the cost may increase, which is not desirable.
[0022]
In the process of treating the powder with a silicon-based polymer compound dissolved in an organic solvent, the polymer is dissolved in a solvent and mixed with the powder in a diluted state, and this slurry is dispersed and contacted by rotating a stirring blade in a container. An agitation method in which the slurry is dispersed in an air stream and a spray method in which the slurry is instantaneously dried can be suitably employed.
[0023]
In the above treatment step, the organic solvent is distilled off by raising the temperature or reducing the pressure. Usually, the temperature is higher than the boiling point of the solvent, specifically, a temperature of about 40 to 200 ° C. under a reduced pressure of 1 to 100 mmHg. It is effective to dry with stirring.
[0024]
After the treatment, it is allowed to stand at a temperature of about 40 to 200 ° C. in a dry atmosphere or under reduced pressure for a while, so that the solvent is effectively distilled off and the treated powder is dried. The body can be manufactured.
[0025]
Next, in the present invention, as a second step, the silicon polymer compound-treated powder formed in the first step is first subjected to metal salt treatment. This is a method in which the surface of the silicon polymer compound-treated powder is brought into contact with a solution containing a metal salt. In this treatment, the metal colloid is formed on the surface of the coating film of the silicon polymer compound by the reducing action of the silicon polymer compound. And a metal film is formed.
[0026]
Here, as the metal salt, a metal salt having a standard oxidation-reduction potential of 0.54 V or more is suitable. More specifically, a salt such as gold (standard oxidation-reduction potential 1.50 V), palladium (standard oxidation-reduction potential 0.99 V), silver (standard oxidation-reduction potential 0.80 V), or the like is preferably used. It should be noted that a salt such as copper (standard oxidation-reduction potential 0.34 V) or nickel (standard oxidation-reduction potential 0.25 V) having a standard oxidation-reduction potential lower than 0.54 V is difficult to reduce with a silicon-based polymer compound.
[0027]
Examples of the gold salt include Au ⁺ or Au ³⁺ , and specific examples include NaAuCl ₄ , NaAu (CN) ₂ , NaAu (CN) _{4 and the} like. The palladium salt contains Pd ^{2+ and} can usually be expressed in the form of Pd—Z ₂ . Z is a salt of halogen such as Cl, Br, and I, acetate, trifluoroacetate, acetylacetonate, carbonate, perchlorate, nitrate, sulfate, oxide, and the like. Specifically, PdCl ₂ , PdBr ₂ , PdI ₂ , Pd (OCOCH ₃ ) ₂ , Pd (OCOCF ₃ ) ₂ , PdSO ₄ , Pd (NO ₃ ) ₂ , PdO and the like are exemplified. The silver salt can be dissolved in a solvent to produce Ag ⁺ , and can usually be expressed in the form of Ag-Z (Z can be a salt of perchlorate, borate, phosphate, sulfonate, etc.). . Specifically, AgBF ₄ , AgClO ₄ , AgPF ₆ , AgBPh ₄ , Ag (CF ₃ SO ₃ ), AgNO _{3 and the} like are exemplified.
[0028]
As a contact method for treating powder with a solution containing a metal salt, a solution containing a metal salt is prepared using a solvent that does not dissolve the silicon-based polymer and can dissolve or disperse the metal salt. A method in which a powder coated with a silicon-based polymer film is put into and contacted with a metal salt is suitable. By performing the treatment in this manner, the metal salt is adsorbed and reduced on the surface of the silicon-based polymer film of the powder coated with the silicon-based polymer to form a metal-coated powder.
[0029]
Here, the solvent that does not dissolve the silicon-based polymer and can dissolve or disperse the metal salt includes water, ketones such as acetone and methyl ethyl ketone, alcohols such as methanol and ethanol, dimethylformamide, and dimethyl sulfoxide. And aprotic polar solvents such as hexamethylphosphoric triamide, among which water is preferably used.
[0030]
The concentration of the metal salt varies depending on the solvent in which the salt is dissolved, but is preferably from 0.01% to a saturated salt solution. If the concentration is less than 0.01%, the effect of the plating catalyst may not be sufficient. If the concentration exceeds the saturated solution, solid salt may be precipitated, which is not preferable. In addition, when the solvent is water, the concentration of the metal salt is preferably 0.01 to 20%, particularly preferably 0.1 to 5%. The silicon-based polymer compound-treated powder may be immersed in the metal salt solution at a temperature of room temperature to 70 ° C. for 0.1 to 120 minutes, more preferably about 1 to 15 minutes. Thereby, the metal colloid processing powder can be manufactured.
[0031]
In the present invention, the solution containing the metal salt is treated in the presence or absence of a surfactant, and it is particularly desirable to carry out the treatment in the presence of a surfactant. When carried out in the presence of a surfactant, the powder surface becomes hydrophobic due to the treatment with the silicon polymer compound in the first step, so that the affinity with the solvent for dissolving the metal salt is reduced and the powder surface is dispersed in the liquid. It can be prevented that the efficiency of the metal salt reduction reaction is reduced, and the silicon-based polymer compound-treated powder can be easily dispersed in a solution containing the metal salt in a short time.
[0032]
Here, as the surfactant, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant can be used.
[0033]
As the anionic surfactant, a sulfonate, sulfate, carboxylate, or phosphate ester salt can be used. Moreover, as a cationic surfactant, an ammonium salt type, an alkylamine salt type, and a pyridinium salt type can be used. As amphoteric surfactants, betaines, aminocarboxylic acids, amine oxides, and nonionic surfactants can be used ethers, esters, and silicones.
[0034]
More specifically, as an anionic surfactant, alkylbenzene sulfonate, sulfosuccinate, polyoxyethylene sulfate alkyl salt, alkyl phosphate, long chain fatty acid soap and the like can be used. Further, as the cationic surfactant, alkyltrimethylammonium chloride salt, dialkyldimethylammonium chloride salt, alkylpyridinium chloride salt and the like can be used. As the amphoteric surfactant, betaine sulfonate and betaine aminocarboxylic acid amine salt can be used. As the nonionic surfactant, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, polyoxyalkylene-modified polysiloxane and the like can be used. In addition, a commercially available aqueous solution containing such a surfactant, for example, the trade name Mama Lemon (manufactured by Lion Corporation), etc. can also be used.
[0035]
In the case of adding a surfactant, the amount of the surfactant added is preferably such an amount that the silicon-based polymer-coated powder is uniformly dispersed in the surfactant solution or the metal salt solution containing the surfactant. It is desirable to use in the range of 0.0001 to 10 parts by weight, particularly 0.001 to 1 part by weight, especially 0.01 to 0.5 part by weight, based on 100 parts by weight of the salt solution. If the amount added is too small, the effect may be poor. If the amount is too large, it may adversely affect the throwing power of the plating or cause discoloration of the metal after plating.
[0036]
As a treatment method, when a surfactant is used, the silicon polymer compound-treated powder is first brought into contact with a surfactant or a surfactant diluted with water, and stirred to disperse, and then contains a metal salt. It is preferable to make it contact with a solution, and the reaction which forms a metal on this coating film surface by the reduction | restoration effect | action of a silicon type polymer compound can be advanced rapidly by this.
[0037]
When the surfactant is not used, it is preferable that the silicon-based polymer compound-treated powder is brought into contact with a solvent and sufficiently stirred and dispersed.
[0038]
After the treatment, treatment with a solvent similar to the above not containing a metal salt, except for unnecessary metal salt not supported on the powder, it is preferable to dry and remove the unnecessary solvent from the powder at the end, Thereby, metal-coated powder can be obtained. Drying is usually preferably performed at 0 to 150 ° C. under normal pressure or reduced pressure.
[0039]
Furthermore, in the method of the present invention, after performing the above steps, the metal-coated powder is subjected to electroless plating. By performing the electroless plating process using the metal colloid generated in the above process as a catalyst, it is possible to obtain a powder that is more completely coated with various metals.
[0040]
In this case, as the electroless plating solution, those containing metals such as copper, nickel, cobalt, palladium, gold, platinum, rhodium, etc. are preferably used, but those containing gold, copper, nickel are particularly preferred. The electroless plating solution usually contains a metal salt and a reducing agent such as sodium hypophosphite, hydrazine and sodium borohydride, and a complexing agent such as sodium acetate, phenylenediamine and sodium potassium tartrate. Usually, those containing metals such as copper, nickel, silver, and gold are commercially available as electroless plating solutions and can be obtained at low cost.
[0041]
In the present invention, the treatment with the electroless plating solution is performed in the presence of a surfactant. In this case, it is preferable to pre-treat the metal-coated powder to be added to the electroless plating solution with a surfactant once more, or to add a surfactant to the electroless plating solution to perform plating. The surface of the powder coated with a silicon-based polymer compound can prevent the plating from proceeding well due to bubbles such as hydrogen produced as a by-product during the plating reaction, and prevent the metal throwing power from deteriorating. Can be satisfactorily coated with a metal coating without unevenness.
[0042]
In this case, the surfactant used in the electroless plating process may be the same as or different from that used in the initial metal salt treatment (treatment with a solution containing a metal salt). Although good, it is more preferable to use different types of surfactants. For example, an anionic surfactant such as sodium alkylbenzene sulfonate is used to improve contact with an aqueous metal salt solution, and a nonionic surfactant such as polyoxyethylene fatty acid ester or polyoxyalkylene-modified polysiloxane is used before the electroless plating treatment. Is preferably used.
[0043]
Similarly, the addition amount of the surfactant is such that the metal-coated powder can be uniformly dispersed in the electroless plating solution, and bubbles such as hydrogen gas generated by the progress of electroless plating adhere to the powder. In an amount that does not hinder the contact, and is 0.0001 to 10 parts by weight, particularly 0.001 to 1 part by weight, especially 0.01 to 0.5 part by weight, based on 100 parts by weight of the electroless plating solution. It is desirable to use in a range. If the amount added is too small, the effect may be poor, and if it is too large, it may adversely affect the throwing power of the plating or cause discoloration of the metal after plating.
[0044]
The plating temperature is preferably 15 to 120 ° C., particularly 25 to 85 ° C., and the contact time is 1 minute to 16 hours, particularly 10 to 60 minutes. In addition, after the electroless plating treatment, it is desirable to finally wash with water in order to remove unnecessary surfactant.
[0045]
If necessary, an insulating layer made of a ceramic layer can be formed by subjecting the metal-coated powder to a high temperature treatment. The high temperature treatment is usually performed at 200 to 1200 ° C., particularly 300 to 900 ° C. for 1 minute to 24 hours, particularly 30 minutes to 4 hours. By this high-temperature treatment, the silicon-based polymer between the powder and the metal changes to ceramic, and has higher heat resistance, insulation, and adhesion. In particular, when polysilane is treated at high temperature, the Si-Si bond is broken and various elements enter and stabilize, so if the atmosphere at this time is performed in an oxidizing system such as in the air, such as ceramics of silicon oxide, ammonia gas, etc. When performed in a reducing atmosphere, a silicon nitride ceramic can be obtained, and when performed in an inert atmosphere such as argon or in a vacuum system, a silicon carbide ceramic can be obtained.
[0046]
【The invention's effect】
According to the method for producing a metal-coated powder of the present invention, a powder coated with a metal can be obtained efficiently and efficiently by an inexpensive and simple process, and this powder has conductivity and catalytic ability. Useful for fillers and antibacterial agents. This metal-coated powder can be made into a metal-coated powder in which a film having excellent heat resistance such as silicon oxide and silicon carbide is formed by changing the conditions of post-treatment such as heat treatment, and has wide application. .
[0047]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.
[0048]
(Synthesis example)
Production of phenyl polysilane (hereinafter abbreviated as PPHS):
Bis (cyclopentadienyl) dimethylzirconocene as a catalyst in the system was prepared by adding a diethyl ether solution of methyllithium to bis (cyclopentadienyl) dichlorozirconocene in an argon-substituted flask. Phenylsilane was added to this at 50 times mole of the catalyst, and the mixture was heated and stirred at 150 ° C. for 24 hours. Thereafter, molecular sieves were added and filtered to remove the catalyst. As a result, a PPHS solid having a weight average molecular weight of 2,600 was obtained almost quantitatively.
[0049]
Production of PPHS treated spherical silica:
As the powder, spherical silica US-10 (manufactured by Mitsubishi Rayon Co., Ltd .; average particle size 10 μm) was used. 5 g of PPHS was dissolved in 65 g of toluene, and this solution was added to 100 g of US-10 and stirred for 1 hour to make a slurry. In a rotary evaporator, 65 g of toluene was distilled off at a temperature of 80 ° C. and a pressure of 45 mmHg, followed by drying. As a result, PPHS-treated spherical silica was obtained. This PPHS-treated spherical silica was finally crushed by a roller or the like.
[0050]
[Example 1]
1-1: Production of palladium colloid-precipitated silica PPHS-treated spherical silica is hydrophobized and floats on the surface of water when charged into water. As a surfactant, 100 g of the PPHS-treated spherical silica obtained in the synthesis example was added to 50 g of a 0.5% aqueous solution of sodium dodecylbenzenesulfonate as a surfactant, and the mixture was stirred and dispersed in a short time of about 5 minutes. In the palladium treatment, 70 g of 1% PdCl ₂ aqueous solution (0.7 g as palladium chloride, 0.4 g as palladium) was added to 150 g of the silica-water dispersion, stirred for 30 minutes, filtered, and washed with water. By these treatments, palladium colloid-deposited silica colored in black-gray with a palladium colloid attached to the silica surface was obtained. This silica was isolated by filtration and plated immediately after washing with water.
[0051]
1-2: Production of copper-plated silica 100 g of an electroless copper plating solution C-200LTA / LTB manufactured by High Purity Chemical Laboratory, diluted with the same volume of ion-exchanged water was used as the copper plating solution. The palladium colloid deposited silica was dispersed in a copper plating solution together with 0.5 g of a surfactant KS-538 (an antifoaming agent manufactured by Shin-Etsu Chemical Co., Ltd.). When the liquid temperature was raised from room temperature to 35 ° C. with vigorous stirring, the silica became reddish brown with fine foaming, and metallic copper was deposited on the silica surface.
[0052]
The silica precipitated on the bottom of the plating water was filtered, washed with water, and dried (30 minutes at 50 ° C.) and then baked at 300 ° C. for 1 hour in an electric furnace substituted with nitrogen. By observation with a stereomicroscope, it was found that copper-plated silica whose entire surface was covered with copper was obtained.
[0053]
[Comparative Example 1]
Without using the surfactant sodium dodecylbenzenesulfonate, 100 g of PPHS-treated spherical silica obtained in the above synthesis example was added to 150 g of water, and the mixture was vigorously stirred and dispersed for 30 minutes or more. Processed. Further, when the obtained palladium colloid-deposited silica was plated without using any surfactant KS-538, silica with no metal coating was mixed due to hydrogen bubbles generated during plating.
[0054]
[Example 2]
Without using the surfactant sodium dodecylbenzenesulfonate, 100 g of PPHS-treated spherical silica obtained in the above synthesis example was added to 150 g of water, and the mixture was vigorously stirred and dispersed for 30 minutes or more. Next, in the palladium treatment, 70 g of 1% PdCl ₂ aqueous solution (0.7 g as palladium chloride, 0.4 g as palladium) was added to 250 g of the silica-water dispersion, stirred for 30 minutes, filtered, washed with water. did. By these treatments, palladium colloid-deposited silica colored in black-gray with a palladium colloid attached to the silica surface was obtained.
[0055]
The obtained silica was isolated by filtration, and immediately after washing with water, plating was performed in the presence of the surfactant KS-538 in the same manner as in Example 1. The copper-plated silica thus obtained had a good metal coating.
[0056]
[Comparative Example 2]
After producing palladium colloid-precipitated silica using sodium dodecylbenzenesulfonate as a surfactant as in Example 1, copper plating treatment was performed in the same manner as in Example 1 without using any surfactant KS-538. As a result, due to hydrogen bubbles generated at the time of plating, silica with no metal coating was mixed.
[0057]
Example 3
3-1: Production of palladium colloidal precipitated silica 100 g of PPHS-treated spherical silica obtained in the above synthesis example was added to 50 g of a 0.5% aqueous solution of sodium dodecylbenzenesulfonate as a surfactant and stirred for about 5 minutes. Dispersed in a short time. Palladium treatment, the silica - the 1% PDC1 ₂ solution in water dispersion 150 g (0.7 g as palladium chloride, 0.4 g as palladium) 70 g was added, after stirring for 30 minutes, filtered and washed with water. By these treatments, a black-gray colored silica with palladium colloid adhered to the silica surface was obtained. This palladium colloidal precipitated silica was isolated by filtration and plated immediately after washing with water.
[0058]
3-2: Nickel plating 100 g of electroless nickel plating solution Ni-901 manufactured by High-Purity Chemical Laboratory, diluted with 5 times the volume of ion-exchanged water was used as the nickel-plating solution. Palladium colloidal precipitated silica was dispersed in a nickel plating solution together with 0.5 g of a surfactant KS-538 (an antifoaming agent manufactured by Shin-Etsu Chemical Co., Ltd.). When the liquid temperature was raised from room temperature to 65 ° C. with vigorous stirring, the silica became black with fine foaming, and metallic nickel precipitated on the silica surface.
[0059]
3-3: Gold-plated silica (1)
As a gold plating solution, 100 g of electroless gold plating solution K-24N manufactured by High Purity Chemical Laboratory was used without dilution. Silica with metallic nickel deposited on the entire surface obtained in 3-2 above was dispersed in a gold plating solution. When the liquid temperature was raised from room temperature to 95 ° C. with vigorous stirring, the silica became golden with fine foaming, and gold was deposited on the silica surface.
[0060]
The silica precipitated on the bottom of the plating water was filtered, washed with water and dried (30 minutes at 50 ° C.) and then baked at 500 ° C. for 1 hour in an electric furnace substituted with nitrogen. By observation with a stereomicroscope, it was found that silica whose entire surface was covered with gold was obtained. As for this silica, palladium, nickel, and gold were detected by IPC analysis.
[0061]
Example 4
4-1: Production of gold colloid-precipitated silica Using sodium dodecylbenzenesulfonate as a surfactant, 100 g of this polysilane-treated silica was added to 50 g of this 0.5% aqueous solution and stirred for a short time of about 5 minutes. Distributed. In the gold treatment, 70 g (2.1 g as sodium chloroaurate) of a 3% NaAuCl ₄ aqueous solution was added to 150 g of the silica-water dispersion, stirred for 30 minutes, filtered, and washed with water. By these treatments, mauve colored silica with colloidal gold adhered to the silica surface was obtained. This gold colloidal precipitated silica was isolated by filtration and plated immediately after washing with water.
[0062]
4-2: Gold-plated silica (2)
Gold colloidal precipitated silica was dispersed in the electroless gold plating solution together with 0.5 g of a surfactant KS-538 (an antifoaming agent manufactured by Shin-Etsu Chemical Co., Ltd.). When the liquid temperature was raised from room temperature to 85 ° C. with vigorous stirring, the silica became golden with fine foaming, and gold was deposited on the silica surface.
[0063]
Silica precipitated on the bottom of the plating water was filtered, washed with water, and dried (30 minutes at 50 ° C.) and then baked at 500 ° C. for 1 hour in an electric furnace substituted with nitrogen. By observation with a stereomicroscope, it was found that silica whose entire surface was covered with gold was obtained. In this silica, only gold was detected by IPC analysis, and metal species such as palladium, nickel and copper were not detected.

Claims (3)

(1) A powder is treated with a silicon-based polymer compound having a Si—Si bond in a molecule represented by the following general formula (1) in which the powder is dissolved in an organic solvent, and the powder surface is treated with the silicon-based polymer compound. A step of coating with a coating,
(R ¹ _m R ² _n X _p Si) _q (1)
Wherein R ¹ and R ² are each a hydrogen atom, a substituted or unsubstituted monovalent hydrocarbon group, X is the same group as R ¹ , an alkoxy group, a halogen atom, an oxygen atom or a nitrogen atom. 0.1 ≦ m ≦ 1, n is 0.1 ≦ n ≦ 1, p is 0 ≦ p ≦ 0.5, and 1 ≦ m + n + p ≦ 2.5, q is 10 ≦ q ≦ 100 , An integer of 1,000.)
(2) The powder coated with the coating made of the silicon-based polymer compound in the first step is treated with a solution containing a metal salt in the presence or absence of a surfactant, and the silicon-based polymer compound Forming a metal film by supporting a metal on the surface of the film, and then treating with an electroless plating solution in the presence of a surfactant to form a film from the electroless plating solution. A method for producing a metal-coated powder.   The method for producing a metal-coated powder according to claim 1, wherein the solution containing a metal salt is a solution containing a metal having a standard oxidation-reduction potential of 0.54 V or more. The method for producing a metal-coated powder according to claim 1 or 2 , wherein the electroless plating solution contains a metal ion selected from gold, copper and nickel.