JP3389858B2 - Metal-coated powder and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a conductive filler, an antibacterial agent, a paint, a coating agent, etc., which is coated with a metal coating capable of exhibiting excellent characteristics such as electrical characteristics, catalytic ability and heat resistance with good adhesion. The present invention relates to a metal-coated powder that can be used in a wide range of fields as a material and a method for inexpensively and easily producing this metal-coated powder.

[0002]

PRIOR ART AND PROBLEMS TO BE SOLVED BY THE INVENTION Powder,
In particular, the metal-coated powder produced by coating the non-conductive powder with various metals has a high degree of freedom in selecting the material to be the base filler, and is used as a conductive filler or an antibacterial agent as a paint,
Applications are expected in a wide range of fields such as fillers and coating agents. For this metal-coated powder, various manufacturing methods have been studied, and among them, the vacuum deposition method and the electroless plating method have been mainly put into practical use.

However, the vacuum evaporation method is expensive in equipment,
There is a problem that a sufficiently high conductivity cannot be obtained.

Further, in the electroless plating method, a pretreatment step of applying a noble metal catalyst to the powder, which is called an activation treatment step, is essential. This pretreatment step is usually performed by bringing the powder into contact with an aqueous solution of stannous chloride to adsorb tin ions into the powder and then contacting with an aqueous solution of palladium chloride before the powder is placed in the electroless plating solution. This is for adsorbing palladium on the powder. However, in this method, the tin salt is corrosive and there is a problem in the adhesion of the metal coating. Therefore, in order to avoid the corrosiveness of the tin salt and to produce a powder having a metal film with better adhesion, a silane coupling agent (eg, γ-aminopropyltriethoxysilane) is used.
Using a silane monomer such as that described in JP-A-61-2
57479, JP-A-62-297471)
Alternatively, a method using a palladium colloid sol using a reducing agent such as NaBH ₄ (JP-A-63-79975) has been proposed.

However, under the present circumstances, it is not always possible to obtain a good metal-coated powder by these production methods.

On the other hand, in the field of antibacterial agents, an inorganic substance such as zeolite having an ion exchange ability is used as a metal coat, or an inorganic substance treated with a silane monomer such as alkoxysilane having an amino group is used to produce silver, copper,
It is already known to produce an inorganic substance that traps metal ions having an antibacterial effect such as zinc, lead and tin.

However, in this method, since the metal is captured as an ion and is not sufficiently supported on the powder surface, the metal disappears due to a change in pH or heat release, and the antibacterial effect is reduced or discolored. There was a problem.

Therefore, it has been desired to develop a metal-coated powder that does not have these problems and a method for producing the same.

The present invention has been made in view of the above circumstances, and is coated with a metal coating which can exhibit excellent characteristics such as electrical characteristics, catalytic ability, and heat resistance, and has excellent adhesion to coated powder. An object of the present invention is to provide a metal-coated powder and a method for producing the metal-coated powder that can be obtained at a low cost and in a simple process.

[0010]

Means for Solving the Problems and Modes for Carrying Out the Invention As a result of intensive studies to achieve the above-mentioned object, the present inventor has treated the powder with polysilane and coated the surface of the powder with a coating composed of polysilane. After performing the first step of coating, the powder coated with the coating of polysilane in this first step is treated with a solution containing a metal salt, and a metal is supported on the surface of the coating of polysilane to form a metal coating. By performing the second step, and if necessary electroless plating thereafter, the powder surface is coated with a film made of polysilane, and the metal is supported on the surface of the powder by a simple and inexpensive process. A metal-coated powder on which a film is formed can be obtained, and this metal-coated powder can exhibit excellent properties such as electrical characteristics, catalytic activity, and heat resistance, and the metal film firmly adheres to the powder. With conductive filling Found antimicrobial agents, paints, that are available in a wide range of fields as a coating agent or the like.

In this case, the silicon-based polymer is a polymer which is very interesting in view of the metallicity and electron delocalization of silicon, high heat resistance and flexibility, and good thin film forming properties, as compared with carbon. Polysiloxane having a hydrogen atom directly bonded to a silicon atom is known as a reducing polymer. In addition, some silicon-based polymers, such as polysilane, often serve as a precursor of a silicon carbide ceramic material, and polysiloxane serves as a precursor of a silicon oxide ceramic material, which often become an insulating material having excellent heat resistance by heat treatment or the like. Are known.

The present inventor brings the metal ion solution into contact with a powder whose surface is coated with polysilane, which is a silicon-based polymer having such a reducing action, and the metal ion solution is reduced to give a powder. Metal is formed on the surface of the body and is firmly supported and forms a metal coating. Therefore, a metal-coated powder coated with a metal coating having excellent properties with excellent adhesion is industrially advantageously manufactured. The inventors have found out what can be done and have completed the present invention.

Therefore, the present invention provides (I) a metal-coated powder, characterized in that the surface of the powder is coated with a polysilane coating, and the surface of the polysilane is loaded with a metal to form a metal coating. (II) (1) a step of treating the powder with polysilane and coating the surface of the powder with a coating made of polysilane, (2) the powder coated with the coating made of polysilane in the first step is treated with a metal salt. A method for producing a metal-coated powder, comprising the step of forming a metal coating by supporting a metal on the surface of the coating made of polysilane to treat the metal with a solution containing the above.

The present invention will be described in more detail below. In the metal-coated powder of the present invention, the surface of the powder is coated with a film made of polysilane, and a metal is supported on the surface of the film made of polysilane. Are formed.

Such a metal-coated powder of the present invention includes (1) a step of treating the powder with polysilane and coating the surface of the powder with polysilane, and (2) a coating of polysilane in the first step. It can be manufactured by treating the powder thus obtained with a solution containing a metal salt, and carrying out a step of supporting a metal on the surface of the coating film made of polysilane to form a metal coating film.

First, in the first step, the surface of the powder is treated with a silicon polymer having a reducing property to form this film.

As the powder used in the present invention, for example, insulating powder such as silica, alumina and alumina silicate, semiconductive powder such as titanium oxide and zinc oxide, conductive powder such as carbon and aluminum. And so on. The shape is not particularly limited, and various shapes such as powder, fiber, and flakes can be used.

In the present invention, polysilane is used as the silicon-based polymer having a reducing action.

As the polysilane, a polymer compound represented by the following general formula (1) having a Si-Si bond in the main chain is preferable.

[0020]       (R¹ _mR² _nX_pSi)_q                                (1) (In the formula, R¹, R²Is a hydrogen atom or a substituted or unsubstituted
Monovalent hydrocarbon group, X is R ¹, Alkoxy group, halogen source
Child, oxygen atom or nitrogen atom, and m is 0.1 ≦ m ≦
2, n is 0 ≦ n ≦ 1, p is 0 ≦ p ≦ 0.5, 1 ≦ m + n
A number satisfying + p ≦ 2.5, q is 4 ≦ q ≦ 100,00
It is an integer that satisfies 0. )

In the polysilane of the above formula (1),
R ¹ and R ² are a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group, and R ¹ and R ² may be the same or different from each other, but as the above monovalent hydrocarbon group, Is an aliphatic, alicyclic or aromatic hydrocarbon group. In the case of an aliphatic or alicyclic hydrocarbon group, it has 1 to 12 carbon atoms, preferably 1 to 6 carbon atoms, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, cyclopentyl group, cyclohexyl group. Etc. The aromatic hydrocarbon group preferably has 6 to 14 carbon atoms, more preferably 6 to 10 carbon atoms, such as a phenyl group,
Examples thereof include a tolyl group, a xylyl group, a naphthyl group, a benzyl group and a phenethyl group. As the substituted hydrocarbon group, a part or all of the hydrogen atoms of the unsubstituted hydrocarbon group exemplified above are halogen atoms, alkoxy groups, amino groups,
Those substituted with an aminoalkyl group, for example, a monofluoromethyl group, a trifluoromethyl group, an m-dimethylaminophenyl group and the like can be mentioned. As described above, X is the same group as R ¹ , an alkoxy group, a halogen atom or the like, and the alkoxy group has a carbon number of 1 to 4 such as a methoxy group, an ethoxy group or an isopropoxy group, and a halogen atom. Examples thereof include a fluorine atom, a chlorine atom and a bromine atom, and a methoxy group and an ethoxy group are usually used.

M is 0.1 ≦ m ≦ 2, especially 0.5 ≦ m ≦
2, n is 0 ≦ n ≦ 1, p is 0 ≦ p ≦ 0.5, and particularly 0 ≦ p
≦ 0.2 and 1 ≦ m + n + p ≦ 2.5, particularly 1.5 ≦ m + n + p ≦ 2, and q is 4 ≦
It is an integer in the range of q ≦ 100,000, particularly 10 ≦ q ≦ 10,000.

[0023]

[0024]

[0025]

[0026]

Here, the method for treating the powdery silicon-based polymer is not particularly limited, but a wet method using a liquid such as a solvent and a dry method not using it are adopted. Among them, the wet method is preferable, and particularly, A polymer is dissolved in a solvent, mixed with powder in a diluted state, and the slurry is stirred and stirred by rotating a stirring blade in a container, or a spraying method in which the slurry is dispersed in an air stream and dried immediately. Can be preferably used.

In the above-mentioned wet method, as an example of the solvent for dissolving the silicon polymer, aromatic hydrocarbons such as benzene, toluene and xylene, and ether solvents such as tetrahydrofuran and dibutyl ether are preferably used. . The concentration of the polymer solution is preferably 0.01 to 50% by weight, particularly 1 to 20% by weight.

Both the stirring method and the spraying method can be carried out by the usual method using the above polymer solution. After the processing, the solution is left to stand for a while in a dry atmosphere or under reduced pressure.
It is effective to dry the treated powder by leaving it at a temperature of about 0 to 200 ° C.

The film thickness of the silicon-based polymer coating thus formed is 0.001 to 10 μm, particularly 0.01.
Approximately 1 μm is preferable.

Next, in the metal salt treatment of the powder in the second step,
The powder in which the silicon-based polymer film is formed in the first step is brought into contact with a solution containing a metal salt, whereby the metal is supported on the surface of the silicon-based polymer film by the reducing action of the silicon-based polymer and a metal film is formed. It is what is done.

Here, various metal salts can be used, but silver salts, palladium salts and the like are preferable. The silver salt is capable of being dissolved in a solvent to form Ag ⁺ , and can be usually represented in the form of Ag-Z (Z can be a salt of perchlorate, borate, phosphate, sulfonate, etc.). Specific examples of the silver _{salts, AgBF 4, AgClO 4, AgPF} 6, AgBP
h ₄ , Ag (CF ₃ SO ₃ ), AgNO _{3 and the} like are preferably used.

As the palladium salt, Pd²⁺Do not include
It is usually Pd-Z₂Can be expressed in the form of. Z
Is halogen such as Cl, Br, I, acetate, trif
Luoroacetate, acetylacetonate, carbon
G, Perchlorate, Nate, Sulfate, Oh
It is salt such as quiside. Specifically as a palladium salt
Is PdCl₂, PdBr ₂, PdI₂, Pd (OCOC
H₃)₂, Pd (OCOCF₃)₂, PdSO_Four, Pd (N
O₃)₂, PdO and the like are preferably used.

As a contact method for treating the powder with a solution containing a metal salt, a solution containing a metal salt is prepared using a solvent which does not dissolve the silicon-based polymer portion and can dissolve or disperse the metal salt. Then, a method in which a powder coated with a silicon-based polymer film is added to this solution and brought into contact with a metal salt is suitable. By such treatment, the metal salt is adsorbed on the surface of the silicon-based polymer coating film of the powder coated with the silicon-based polymer, and is also reduced and supported to form the metal-coated powder.

Here, as the solvent which does not dissolve the polymer portion and can dissolve or disperse the metal salt, water, hydrocarbons such as hexane, octane and cyclohexane, ketones such as acetone and methyl ethyl ketone, Esters such as ethyl acetate, alcohols such as methanol and ethanol, aprotic polar solvents such as dimethylformamide, dimethylsulfoxide and hexamethylphosphoric triamide, nitromethane, acetonitrile and the like, particularly alcohols such as water and ethanol. Is preferably used.

Although the concentration of the metal salt is appropriately selected,
The amount can be 0.01 to 50% by weight, particularly 0.1 to 10% by weight, and the powder can be treated at room temperature to 60 ° C. for about 1 to 60 minutes.

After the above treatment, the treatment is carried out with the same solvent as above containing no metal salt to remove the unnecessary metal salt not carried by the powder, and finally the unnecessary solvent is removed from the powder by drying. Is preferable, and thereby a metal-coated powder can be obtained. Drying is preferably carried out usually at 0 to 150 ° C. under normal pressure or reduced pressure.

Further, in the method of the present invention, it is preferable that the metal-coated powder is subjected to electroless plating treatment, if necessary, after performing the second step. By performing the electroless plating treatment, it is possible to obtain a powder completely covered with various metals.

In this case, the electroless plating solution is copper,
Those containing metals such as nickel, cobalt, palladium, gold, platinum and rhodium are preferably used. The electroless plating solution usually contains a metal salt containing a reducing agent such as sodium hypophosphite, hydrazine and sodium borohydride, a pH adjusting agent such as sodium acetate, and a complexing agent such as phenylenediamine and sodium potassium tartrate. . Usually, it is commercially available as an electroless plating solution and can be obtained at low cost.

The plating treatment temperature is 15 to 120 ° C., especially 25 to 85 ° C., and the contact time is 1 minute to 16 hours, especially 10 to 10.
60 minutes is preferred.

If necessary, the metal-coated powder may be treated at a high temperature to form an insulating layer made of a ceramic layer. High temperature treatment is usually 200-12
00 ° C., particularly 300 to 900 ° C., for 1 minute to 24 hours, and particularly 30 minutes to 4 hours. By this high-temperature treatment, the silicon-based polymer between the powder and the metal is changed to ceramic, which has higher heat resistance, insulation and adhesion. In particular, when polysilane is treated at a high temperature, the Si-Si bond is broken and various elements enter and become stable. Therefore, if the atmosphere at this time is carried out in an oxidizing system such as in the air, it will not be possible to use silicon oxide ceramics or ammonia gas. In a reducing atmosphere, a silicon nitride ceramic can be obtained. In an inert atmosphere such as argon, or a vacuum system, a silicon carbide ceramic can be obtained.

[0042]

Industrial Applicability The metal-coated powder of the present invention is a conductive filler which is coated with a metal film which has excellent characteristics such as electric characteristics, catalytic ability and heat resistance and has good adhesion to the coating powder. It is also useful as an antibacterial agent, paint, coating agent and the like. Furthermore,
This metal-coated powder can be treated with an electroless plating solution to form a powder coated with various metals, and by performing post-treatments such as heat treatment, it is possible to obtain excellent properties such as silicon oxide and silicon carbide. By forming a film having heat resistance, it can be widely used as an insulating material or the like that requires heat resistance. Further, according to the method for producing a metal-coated powder of the present invention, the metal-coated powder can be produced at a low cost and with simple steps.

[0043]

EXAMPLES The present invention will be specifically described below with reference to synthesis examples, examples and comparative examples, but the present invention is not limited to the following examples.

[Synthesis Example] A diethyl ether solution of methyllithium was added to bis (cyclopentadienyl) dichlorozirconocene in a flask purged with argon to prepare bis (cyclopentadienyl) dimethylzirconocene in the system. This bis (cyclopentadienyl) dimethylzirconocene was used as a catalyst, phenylsilane was added in a 50-fold molar amount, and the mixture was heated and stirred at 150 ° C. for 24 hours. After that, molecular sieves were added and filtered to remove the catalyst, and a phenylpolysilane solid having a weight average molecular weight of 2,600 was obtained almost quantitatively.

[Examples, Comparative Examples, Reference Examples] Spherical silica (Admafine SO-25H) was treated with the polysilane obtained in the above synthesis example and the methylhydrogenpolysiloxane represented by the following formula by the following methods. did.

[0046]

[Chemical 1] Treatment method 1: Silica was put into a 5% THF solution of polysilane, and after 1 hour, it was filtered and dried. Treatment method 2: Silica was added to a 5% toluene solution of polysiloxane, and after 1 hour, it was filtered and dried.

By these treatments, the silica is hydrophobized,
When added to water, it began to float on the surface of the water.

Next, with respect to 100 parts by weight of the above silica,
200 parts by weight of a 1% PdCl ₂ aqueous solution (2 parts by weight as palladium chloride and 1.2 parts by weight as palladium) was added, and the water was evaporated to dryness by natural evaporation. By these treatments, the silica was palladiumed and colored reddish brown to black gray.

Further, the silica thus palladium-ized is electroless copper plating solution (C-200 manufactured by Kojundo Chemical Laboratory Co., Ltd.).
LTA / LTB was diluted with the same volume of ion-exchanged water). The silica was floating on the surface immediately after being charged, but after about 5 minutes, it was foamed and precipitated on the water bottom, and both the liquid and the silica became black. The silica was filtered and dried. As a result, the polysilane-treated silica of the above treatment method 1 (Example)
A powder having a surface covered with a reddish-brown copper coating was obtained with the polysiloxane-treated silica of Reference Method 2 (Reference Example).

For comparison, a silica-untreated product was put into the same electroless copper plating solution as above, but silica precipitated on the water bottom and did not change at all. When the silica is filtered and dried,
A white powder with a mixture of blue-green and suspected copper sulfate was obtained.

The treated silica was treated at 300 ° C. in a fluorine mixed acid (HF / HClO ₄ ) to remove the silicon content, and then the metal component was redissolved with nitric acid to give an IC.
P by P analysis (Shimadzu ICPS-1000)
Quantification of d and Cu was performed. The results are shown below. Polysilane-treated silica: Pd amount 1,410 ppm, Cu
9.4 wt% polysiloxane-treated silica: Pd amount 600 ppm, Cu
Amount 4.0 wt% Untreated silica: Pd amount undetected, Cu amount 0.02 wt%

Continuation of the front page (56) Reference JP-A-64-62475 (JP, A) JP-A-61-64882 (JP, A) JP-A-61-258868 (JP, A) JP-A-9-59778 (JP , A) JP 10-330948 (JP, A) JP 11-271981 (JP, A) JP 2-14258 (JP, A) JP 60-63378 (JP, A) JP 61-257479 (JP, A) JP-A-62-297471 (JP, A) JP-A-63-79975 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C23C 18/18 H01B 1/00 H01B 1/22

Claims (8)

(57) [Claims] 1. A metal-coated powder, characterized in that the powder surface is coated with a polysilane film, and a metal film is formed by supporting a metal on the polysilane film surface. 2. The metal-coated powder according to claim 1, wherein the polysilane is represented by the following general formula (1). (R ¹ _m R ² _n X _p Si) _q (1) (In the formula, R ¹ and R ² are hydrogen atoms or a substituted or unsubstituted monovalent hydrocarbon group, X is R ¹ , an alkoxy group, a halogen atom, Represents an oxygen atom or a nitrogen atom, and m is 0.1 ≦ m ≦
2, n is 0 ≦ n ≦ 1, p is 0 ≦ p ≦ 0.5, 1 ≦ m + n
A number satisfying + p ≦ 2.5, q is 4 ≦ q ≦ 100,00
It is an integer that satisfies 0. ) 3. A metal-coated powder having an insulating layer composed of a ceramic layer in which the polysilane coating is changed to a ceramic by subjecting the metal-coated powder according to claim 1 to high temperature treatment. 4. A step of (1) treating powder with polysilane and coating the surface of the powder with a coating made of polysilane, (2) coating the powder coated with the coating made of polysilane in the first step with a metal. The method for producing a metal-coated powder according to claim 1, further comprising a step of treating with a solution containing a salt and supporting a metal on the surface of the coating film made of polysilane to form a metal coating film. 5. The method for producing a metal-coated powder according to claim 4, wherein the solution containing a metal salt is a solution containing a metal salt of silver or palladium. 6. A powder coated with a film of polysilane is treated with a solution containing a metal salt of silver or palladium, and silver or palladium is supported on the surface of the film of polysilane to form a silver or palladium film. Then copper,
The method for producing a metal-coated powder according to claim 4, wherein the electroless plating solution containing a metal ion selected from nickel and cobalt is used to form a film from the electroless plating solution. 7. The method for producing a metal-coated powder according to claim 6, after forming a coating film from an electroless plating solution,
A method for producing a metal-coated powder, which comprises performing a high-temperature treatment at 200 to 1200 ° C. to change a coating film made of polysilane into a ceramic to form a ceramic layer. 8. The method for producing a metal-coated powder according to claim 4, wherein the polysilane is represented by the following general formula (1). (R ¹ _m R ² _n X _p Si) _q (1) (In the formula, R ¹ and R ² are hydrogen atoms or a substituted or unsubstituted monovalent hydrocarbon group, X is R ¹ , an alkoxy group, a halogen atom, Represents an oxygen atom or a nitrogen atom, and m is 0.1 ≦ m ≦
2, n is 0 ≦ n ≦ 1, p is 0 ≦ p ≦ 0.5, 1 ≦ m + n
A number satisfying + p ≦ 2.5, q is 4 ≦ q ≦ 100,00
It is an integer that satisfies 0. )