JP2005272956A - Insulation-coated metal particle and production method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide insulation-coated metal particles in which a dense insulation coating having high bonding strength with the surface of each metal particle is formed, and to provide a production method capable of easily producing the insulation-coated metal particles. <P>SOLUTION: The insulation-coated metal particles are obtained by, using a metal organic compound capable of forming a hydroxyl group by hydrolysis, forming a coating derived from a metal oxide sol (such as a silica sol and an alumina sol) on the surface of each metal particle via a -O-Me-O- bond (Me is metals comprised in the metal organic compound). In the method for producing insulation-coated metal particles, after the regulation of the pH in a solution comprising metal particles, a metal organic compound and a metal oxide sol to 3 to 4, the solution is stirred and is left standing to allow a hydroxyl group derived from the metal organic compound to adsorb (bond) on the metal oxide sol or the metal particles; subsequently, the value of the pH in the solution is changed by ≥2 to promote dewatering and condensation reaction, so as to form a -O-Me-O bond; the metal oxide sol is allowed to adsorb (bond) on the metal particles via the bonding; and thereafter, the solution is filtered, dried and heat-treated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to insulating coated metal particles and a method for producing the same. More specifically, the present invention relates to an insulating coated metal particle having a strong bonding force with the surface of the metal particle and having a dense insulating film formed thereon, and a method for producing the same.

  Insulating coated metal particles in which an insulating film is formed on metal particles are required in many applications such as panel members such as liquid crystal display devices, printed circuit board materials, high frequency powder magnetic cores, electromagnetic wave suppression sheets, and magnetic cards in recent years. Has been.

  As a method for producing such insulating coated metal particles, for example, a method in which a mixture of magnetic powder and insulating inorganic powder is dried to form a solid mixture is solidified with a powder molding press (Patent Document 1), machine Conventionally, a method of coating an insulating inorganic material on the surface of metal particles using a mechanical impact force (Patent Document 2), a method of coating by a sol-gel method using a metal alkoxide (Patent Document 3), etc. ing.

Japanese Patent Laid-Open No. 06-260319 JP 2002-368480 A Japanese Patent Laid-Open No. 08-246002

  When the present inventors tried to form an insulating film on the metal particles by the above-mentioned conventional method, in the method of coating the metal particle surface with an insulating inorganic material by mechanical impact force, the metal particle surface is insulated with an insulating inorganic material. Particles could be sprayed and the insulation was improved, but the bonding force between the metal particles and the insulating inorganic particles was weak.For example, the obtained insulating coated metal particles were dispersed in an organic binder and a solvent. As a result, the insulation film was detached due to the shearing force at the time of dispersion, and the insulation of the coating film was not sufficiently obtained. The coating obtained by the method of solidification molding with a powder molding press also has the same problems as described above.

  In addition, the sol-gel method using metal alkoxide exhibits considerable insulation, but the denseness and thickness of the insulation film are not sufficient, and it is necessary to form an insulation film exhibiting higher insulation. I understood.

  The present invention has been made in view of the above circumstances, and has a strong bonding force to the surface of metal particles, an insulation coated metal particle having a dense insulating film formed thereon, and a production capable of easily producing the insulation coated metal particle It aims to provide a method.

  In order to achieve the above object, the present invention uses a metal organic compound capable of forming a hydroxyl group by hydrolysis, and has a -O-Me-O- bond (Me: contained in the metal organic compound) on the metal particle surface. Provided is an insulating coated metal particle formed by coating a coating derived from a metal oxide sol containing one or more selected from silica sol, titania sol, alumina sol, and cerium oxide sol via (metal).

  The present invention also includes a metal organic compound in which metal particles are dispersed in a solvent and capable of forming a hydroxyl group by hydrolysis, and one or more selected from silica sol, titania sol, alumina sol, and cerium oxide sol. After stirring the solution to which the metal oxide sol containing is added, the pH of the solution is adjusted to 3 to 4 and stirred and allowed to stand, whereby the hydroxyl group formed by hydrolysis of the metal organic compound is converted to metal. The hydrolysis / adsorption (bonding) step for adsorbing (bonding) to the oxide sol or metal particles, and the pH of the solution after the hydrolysis / adsorption (bonding) step is set to 2 with respect to pH 3-4. By maintaining the above changes, the dehydration / condensation reaction is promoted in the solution to form —O—Me—O bond (Me: metal contained in the metal organic compound), A dehydration / condensation reaction accelerating step for adsorbing (bonding) metal oxide sol to metal particles via —O—Me—O bond, and a solution after the dehydration / condensation reaction accelerating step is filtered and dried / heat treated. A method for producing insulating coated metal particles, comprising the step of:

In the insulating coated metal particles and the manufacturing method thereof, the metal organic compound is Me (RO) _m (R) _n (where Me represents a metal element of Si, Ti, Zr, or Al, and R represents An alkyl group having 1 to 8 carbon atoms, m + n represents a number equal to the valence of Me, m represents a number of 2 or more, and n represents a number of 0 or 1). Or Me (RO) _m (Y) _n (where Me, R, m + n, m, n are as defined above, respectively, Y is a hydrocarbon group having 1 to 12 carbon atoms, an amino group, It is preferably one or more selected from coupling agents represented by an organic functional group selected from an epoxy group, a vinyl group, an acrylic group, and a methacryl group, or an alkyl acetate.

  Moreover, it is preferable that the primary particle size of the metal oxide contained in the metal oxide sol is 5 to 100 nm.

  The secondary particle size of the metal oxide contained in the metal oxide sol is preferably 200 nm or less.

  The insulating coated metal particles of the present invention have a tight bond between the film and the metal particle surface and have a dense insulating film. Further, the insulating coated metal particles can be easily produced by the production method of the present invention.

  Hereinafter, the present invention will be described in detail.

  The insulating coated metal particles according to the present invention use a metal organic compound capable of forming a hydroxyl group by hydrolysis on the surface of the metal particle, whereby an -O-Me-O- bond (Me: included in the metal organic compound). A metal oxide sol-derived film is formed through a metal).

  The metal particles are not particularly limited and may be appropriately selected depending on the application. For example, metal magnetic particles mainly composed of Fe, Ni, or Co are preferably used.

  As said metal organic compound, what can form a hydroxyl group by hydrolysis is used. In the present invention, those which can be hydrolyzed by reaction with a lower alcohol or water / lower alcohol solvent to form a hydroxyl group are preferably used. Examples of such metal organic compounds include metal alkoxides, coupling agents, metal cetyl acetonates, metal carboxylates and the like in the present invention. Of these, metal alkoxides and coupling agents are preferably used because they are highly reactive and easily produce a polymer composed of a metal-oxygen bond.

As the metal alkoxide, Me (RO) _m (R) _n (where Me represents a metal element of Si, Ti, Zr, Al, R represents an alkyl group having 1 to 8 carbon atoms, m + n represents a number equal to the valence of Me, m represents a number of 2 or more, and n represents a number of 0 or 1). That is, the metal alkoxide having at least two alkoxy groups is preferably used. Note that as the number of alkoxy groups (RO) in one molecule increases and the carbon chain is shorter, the bonding force between the metal particles and the metal oxide sol can be increased, and the reactivity can be increased. In the above formula, since the alkoxy group (RO) is a short chain (1 to 8, preferably 1 to 4 carbon atoms), the bonding force between the metal particles and the metal oxide sol (described later) is enhanced, and the reaction This is preferable because the properties can be improved. N is preferably 0.

Specific examples of such metal alkoxides include Si-based alkoxides such as Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , CH ₃ Si (OCH ₃ ) ₃ , and CH ₃ Si (OC ₂ H ₅ ) ₃ . Ti-based alkoxides such as Ti (OC ₃ H ₇ ) ₄ , Ti (OC ₄ H ₉ ) ₄ , (OC ₄ H ₉ ) ₃ Ti—Ti (OC ₄ H ₉ ) ₃ , Ti (OC ₈ H ₁₇ ) ₄ Zr alkoxides such as Zr (OC ₃ H ₇ ) ₄ and Zr (OC ₄ H ₉ ) ₄ , Al alkoxides such as Al (OC ₃ H ₇ ) ₃ and Al (OC ₄ H ₉ ) ₃ However, it is not limited to these examples.

As the coupling agent, Me (RO) _m (Y) _n (where Me, R, m + n, m, and n are as defined above, respectively, and Y is a hydrocarbon having 1 to 12 carbon atoms. An organic functional group selected from a group, an amino group, an epoxy group, a vinyl group, an acrylic group, and a methacryl group, or an alkyl acetate) is preferably used.

  Examples of the coupling agent include Al coupling agents such as alkyl acetoacetate aluminum diisopropylate, and silane cups such as γ-glycidoxypropyltrimethoxysilane and β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane. Examples include ring coupling agents, Ti coupling agents such as titanium acetyl acetate and titanium ethyl acetate, Zr coupling agents such as zirconium dibutoxybis (acetylacetonate) and zirconium tributoxyethyl acetoacetate. It is not limited to.

  The production of the metal alkoxide is not particularly limited, and a metal alkoxide obtained by a conventional method such as bringing a metal and an alcohol into contact with each other can be used.

  The metal oxide sol used in the present invention is preferably a dispersion in which one or more metal oxides selected from silica sol, titania sol, alumina sol, and cerium oxide sol are dispersed in a solvent. The specific metal oxide sol is particularly preferable for obtaining insulation.

  Since the metal oxide sol has a smaller particle diameter of the metal oxide and can form a denser film, the primary particle size is preferably 5 to 100 nm, particularly preferably 5 to 20 nm. The secondary particle size is preferably 200 nm or less, and particularly preferably 50 nm or less. When the primary particle of the metal oxide is larger than 100 nm and the secondary particle is larger than 200 nm, the adhesion strength of the insulating film tends to be reduced, so that uniform film formation tends to be difficult. The surface of the metal oxide sol preferably has a large number of hydroxyl groups in order to bond strongly with the alkoxy group of the metal alkoxide.

  The production of the metal oxide sol is not particularly limited, and it is preferable to use a product obtained by dispersing a hydrolyzed / condensed metal alkoxide as a starting material in a dispersion medium by a sol-gel method. And the number of hydroxyl groups on the surface of the metal oxide sol can be increased. As the dispersion medium, water, lower alcohol or the like is preferably used, and water is particularly preferable. However, it is not limited to this.

  The insulation-coated metal particles according to the present invention are preferably produced by the following production method.

[Hydrolysis / adsorption (bonding) process]
First, metal particles are dispersed in a solvent, and a solution is prepared by adding the metal organic compound (hereinafter, metal alkoxide will be described as a representative example) and a metal oxide sol.

  As the solvent, a solvent that does not significantly impair the dispersibility of the metal particles, the metal alkoxide, and the metal oxide sol is used. In the present invention, a water / alcohol solvent containing water and a lower alcohol such as methanol, ethanol or isopropanol can be preferably used.

  The metal particles are preferably washed beforehand by acid treatment or the like. Examples of acids that can be used include inorganic acids such as phosphoric acid, hydrochloric acid, and sulfuric acid, and organic acids such as organic carboxylic acids. For example, a 5% hydrochloric acid aqueous solution is kept constant at a liquid temperature of 20 ° C., and the metal magnetic powder is kept at an appropriate time. After the immersion, a method of removing the cleaning liquid with a filter and further washing with water can be used, but the method is not limited to this.

  Subsequently, the acid-treated metal particles are dispersed in a water / alcohol solvent. The metal particles can be dispersed by a bead mill or ultrasonic dispersion, but is not limited to these methods. The metal particles are preferably added to the water / alcohol solvent in an amount of about 5 to 50% by mass, more preferably about 10 to 30% by mass. After the metal particles are dispersed in the primary particles in this manner, the metal alkoxide and the metal oxide sol are added.

  The metal alkoxide is preferably added at a ratio of 0.05 to 30% by mass, particularly 0.1 to 10% by mass with respect to the metal particles. If the addition amount of the metal alkoxide is too small, the bonding strength of the metal oxide sol is weak and a phenomenon such as detachment of the oxide film is likely to occur. There is a tendency for the aggregates to be firmly formed, which is not preferable.

  The metal oxide sol is preferably added at a ratio (solid content ratio) of 1.0 to 30% by mass, particularly 1.5 to 15% by mass with respect to the metal particles. If the addition amount of the metal oxide sol is too small, a phenomenon such as poor insulation (breakdown, etc.) is likely to occur. On the other hand, if the addition amount is excessive, the metal sol There is a tendency to remarkably reduce the characteristics (for example, magnetic characteristics), and this is not preferable.

  Subsequently, the solution in which the metal particles, the metal alkoxide, and the metal oxide sol are added in the solvent is uniformly stirred. The stirring time may be about several minutes and is not particularly limited. The liquid temperature is preferably about 20 to 60 ° C. from the viewpoint of controlling the reaction rate.

  Next, after adjusting the pH of the solution to 3 to 4, the solution is stirred and allowed to stand.

  In the above series of treatments, first, the metal alkoxide is hydrolyzed. By hydrolysis of the metal alkoxide, the alkoxy group of the metal alkoxide becomes a hydroxyl group. The hydroxyl group derived from the metal alkoxide is adsorbed in a hydrogen bond manner with the hydroxyl group on the surface of the metal particle or the metal oxide sol. More specifically, the hydroxyl group derived from the metal alkoxide is adsorbed on an active site on the surface of the metal particle to form a (metal particle-OHHO-Me-OR) bond, or subsequently formed sequentially. Among them, other hydroxyl groups are adsorbed on the metal oxide sol to form a (metal oxide sol-OHHO-Me-OR) bond. These then condense (metal particles-OHHO-Me-OHHO-metal oxide sol) to form a bond.

  The hydrolysis treatment time varies depending on the metal organic compound species (metal species, alkyl group species, alkoxy group species), the pH and temperature of the solution, the ratio of water to alcohol in the solution, etc., but usually about 1 to 3 hours. End with.

  At this time, some hydroxyl groups derived from the metal alkoxide condense with other hydroxyl groups derived from the metal alkoxide in the process of adsorbing with the metal particles or metal oxide sol, resulting in non-uniform oligomerization in the solution. there's a possibility that. The increase in the molecular weight of the oligomer may be disadvantageous for uniformly coating the metal particles with the metal oxide sol and strongly binding them. Therefore, when hydrolyzing the alkoxy group of the metal alkoxide, the dehydration / condensation reaction between the hydroxyl groups can be suppressed, the hydroxyl group can be stably maintained without causing such a reaction, and the above binding / adsorption can be promoted. It is suitable for uniformly treating metal particles with a metal oxide sol.

  Such dehydration / condensation reaction can be suppressed by adjusting the pH of the solution, and the reaction is most suppressed at pH 3-4. Thereby, the adsorption of the hydroxyl group derived from the metal alkoxide to the metal particles and the adsorption (bonding) to the metal oxide sol can be performed stably.

  In addition, pH adjustment can be performed by adding an acid etc., for example. The acid is not particularly limited, and for example, organic acids such as acetic acid and organic carboxylic acids, inorganic acids such as hydrochloric acid, phosphoric acid, hydrochloric acid, and sulfuric acid can be used, but the acid is not limited to these examples.

[Dehydration and condensation reaction acceleration process]
After the hydrolysis / adsorption (bonding) step, the dehydration / condensation reaction of the solution is promoted to bond (metal particle-OHHO-Me-OHHO-metal oxide sol) bond to (metal particle-O-Me-O). -Metal oxide sol) bond. As a result, the metal particles and the metal oxide sol are firmly bonded (adsorbed) via the —O—Me—O bond (metalloxane bond).

  The dehydration / condensation reaction rate can be promoted by changing the pH 3 to 4 solution to a value of pH 2 or higher. Specifically, for example, the pH 3 (~ 4) solution is adjusted to pH 5 (~ 6) or higher, or the pH 3 (~ 4) solution is adjusted to pH 1 (~ 2) or lower. it can. The greater the change in pH value, the higher the effect. Therefore, considering only the point of increasing the dehydration / condensation reaction rate, it can be promoted particularly effectively by bringing the pH closer to 1 or 14. The pH can be adjusted by acid addition or alkali addition.

  However, since it is considered that the metal particles corrode with strong acid or strong alkali, it is necessary to select various pH values and pH adjusters to be changed. If the pH adjuster is added rapidly, the condensation reaction tends to occur non-uniformly in the treatment liquid, so it is desirable to add gradually while stirring.

  In the dehydration / condensation reaction step, it is desirable to add a coupling agent or surfactant having an alkyl group having a large number of carbon atoms to the treatment liquid so as not to form an aggregate due to excessive dehydration / condensation. For example, decyltrimethoxysilane or amine surfactant can be used. In particular, a surfactant of polyoxyethylene (POE) coconut alkylamine has an effect of preventing aggregation.

  Although it is possible to produce metal particles coated with a metal oxide sol without using such pH adjustment or aggregate prevention material, the uniformity of the film and the stability (reproducibility) of the insulation resistance value It becomes good.

[Filtering, drying, heat treatment process]
The solution after the dehydration / condensation step is filtered with a filter or the like, and the treated powder is dried with a heat treatment furnace or the like. In addition, it is desirable that the liquid part in which the dehydration / condensation reaction is not completed is completely completed by heat treatment. The heat treatment temperature is preferably 100 ° C. or higher, and it is necessary to adjust the temperature and time so that the oxidation of the metal particles does not proceed.

  The dehydration / condensation reaction can be promoted by drying / heat treatment to obtain insulating coated metal particles coated with a strongly bonded metal oxide sol-derived coating.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Unless otherwise specified, the blending amount is expressed in mass% with respect to the system in which the component is blended.

I. Insulation coated metal particles (Examples 1 to 4)
Fe-Ni flat metal magnetic powder (manufactured by Dowa Iron Powder Industry Co., Ltd.) was used as metal particles. After the permalloy powder was acid washed, 10 g was added to 100 mL of a mixed solution of isopropyl alcohol and water (5: 5 (mass ratio)), and the mixture was stirred for 10 minutes with an ultrasonic disperser.

  Next, 0.8 g of each metal alkoxide shown in Table 1 below was added, and 1 g of each metal oxide sol (Table 1) dispersed in water was added as a solid content and stirred for 5 minutes. After stirring, acetic acid was added to adjust the pH of the solution to 4 to prepare a treatment liquid. The treatment liquid was stirred at a constant temperature of 25 ° C. for 2 hours.

  Thereafter, ammonia was gradually added while stirring to adjust the pH to 7. The pH value of the solution was maintained for 1 hour.

  The treatment liquid produced by the above method was filtered to remove the solvent, the treated powder was taken out, washed with water, filtered again, and then heat-treated and dried at 120 ° C. for 2 hours to produce insulating coated metal particles.

  In Table 1, “KBM04” (manufactured by Shin-Etsu Chemical Co., Ltd.) was used as the Si-based metal alkoxide, and “organotic TA-25” (manufactured by Ajinomoto Fine Techno Co., Ltd.) was used as the Ti-based metal alkoxide. “PL-07” (manufactured by Tama Chemical Co., Ltd.) was used as the silica sol, and “aluminum sol-10” (manufactured by Kawaken Fine Chemical Co., Ltd.) was used as the alumina sol. For the comparative examples described later, the above products were used for the corresponding components.

  In Table 1, in Example 2, two types of silica sols were mixed at a mass ratio of 1: 1.

In Example 3, Si (OCH ₃ ) ₄ and Ti (OC ₃ H ₇ ) ₄ were mixed and used as a metal alkoxide so as to have a mass ratio of 9: 1.

In Example 4, as the metal alkoxide, Si (OCH ₃ ) ₄ and (CH ₃ ) Si (OCH ₃ ) ₃ were mixed and used at a mass ratio of 9: 1.

(Comparative Example 1)
The Fe—Ni flat metal magnetic powder (untreated permalloy powder) that was not provided with the insulation coating of the present invention was used as Comparative Example 1.

(Comparative Example 2)
In Example 1, a coated metal powder was obtained in the same manner as in Example 1 except that the metal alkoxide was not added.

  That is, flat Fe—Ni metal magnetic powder (permalloy powder) was used as the metal particles. After the permalloy powder was acid washed, 10 g was added to 100 mL of a mixed solution of isopropyl alcohol and water (5: 5 (mass ratio)), and the mixture was stirred for 10 minutes with an ultrasonic disperser. Thereafter, the oxide sol dispersed in water was added at each addition amount, and stirred for 5 minutes.

  After stirring, acetic acid was added to adjust the pH of the solution to 4 to prepare a treatment liquid. After stirring the treatment liquid at a constant temperature of 25 ° C. for 2 hours, ammonia was gradually added while stirring to adjust the pH to 7. The pH value of the solution was maintained for 1 hour.

  The treatment liquid produced by the above method was filtered to remove the solvent, the treated powder was taken out, washed with water, filtered again, and then heat-treated and dried at 120 ° C. for 2 hours to produce insulating coated metal particles.

(Comparative Example 3)
In Example 1, a coated metal powder was obtained in the same manner as in Example 1 except that the metal oxide sol was not added.

  That is, Fe—Ni metal magnetic powder (permalloy powder) was used as the metal particles. After the permalloy powder of each shape was acid-washed, 10 g was added to 100 mL of a mixed solution of isopropyl alcohol and water (5: 5 (mass ratio)) and stirred for 10 minutes by an ultrasonic disperser. Thereafter, 0.8 g of metal alkoxide was added and stirred for 5 minutes.

  After stirring, acetic acid was added to adjust the pH to 4 to prepare a treatment liquid. After stirring the treatment liquid at a constant temperature of 25 ° C. for 2 hours, ammonia was gradually added while stirring to adjust the pH to 7. The treatment liquid produced by the above method was filtered to remove the solvent, the treated powder was taken out, washed with water, filtered again, and then heat treated and dried at 120 ° C. for 2 hours to produce insulating coated metal particles.

(Comparative Example 4)
Comparative Example 4 was obtained by coating a metal particle with a silica powder by mechanical friction.

  That is, as metal particles, 5 g of silica powder (average particle size 200 nm) is mixed with 100 g of flat permalloy powder, and the silica powder is adhered to the metal powder surface by mechanical friction using a rotor type surface treatment device. An insulating film was formed.

  Using the powders (samples) obtained in Examples 1 to 4 and Comparative Examples 1 to 4, the thickness of the insulating film was calculated as follows, and the coating state was observed.

[Insulation coating thickness]
Measure the saturation magnetization of the insulation-treated metal magnetic powder and untreated metal magnetic powder with a vibrating sample magnetometer (VSM), and determine the thickness of the insulation film from the density of the metal oxide sol used and the rate of decrease in saturation magnetization. Was calculated. The results are shown in Table 1.

[Coating condition]
The coating state was observed using an electron microscope (SEM). As a result, in Examples 1 to 4, uniform coating was performed. In Comparative Examples 2 to 3, the coating thickness was insufficient, so that a portion that was not coated was also found and was non-uniform. In Comparative Example 4, the coating thickness was sufficient but not uniform. In addition, the coating powder surface SEM photograph of Example 1 is shown in FIG. 1, the SEM photograph of the coating powder surface of Example 3 is shown in FIG. 2, the untreated powder SEM photograph of Comparative Example 1 is shown in FIG. An SEM photograph of the powder surface is shown in FIG. 4, and an SEM photograph of the coated powder surface of Comparative Example 3 is shown in FIG.
Each is shown.

  Table 1 shows the measurement results of the primary particle diameter and secondary particle diameter of the metal oxide sol used in Examples 1 to 4 and Comparative Examples 2 and 4.

II. Evaluation of Coating Solution A coating solution was prepared using the samples obtained in Examples 1 to 4 and Comparative Examples 1 to 4, and the insulating properties of the coating solution were evaluated. Insulation evaluation was also performed for the following comparative example 5 (coating solution).

(Coating liquid preparation using samples of Examples 1 to 4 and Comparative Examples 1 to 4)
100 g of the sample (treated metal powder) obtained in Examples 1 to 4 and Comparative Examples 1 to 4 was mixed in a 500 mL steel can container, and then 500 g of steel beads having a diameter of 2 mm were added. As the resin binder, 100 g of “polyethersulfone 5003P” (manufactured by Sumitomo Chemical Co., Ltd.) dissolved in N-methyl-2pyrrolidone (NMP) (solid content: 30% by mass) was used. As a dispersant, 0.5 g of (POE) ₇ coconut alkylamine “AMIET105” (manufactured by Kao Corporation) was added.

  The mixture was stirred with a paint shaker for 30 minutes to remove the steel beads to prepare a metal magnetic powder dispersion coating solution.

(Comparative Example 5 (coating solution preparation))
Silica sol (MEK-ST) in which 100 g of untreated Fe-Ni flat metal magnetic powder (Permalloy) and 500 g of steel beads are mixed in a 500 mL steel can and dispersed in methyl ethyl ketone (MEK) (manufactured by Nissan Chemical Co., Ltd.) Was added in an amount of 15 g in terms of solid content, and 1 g of tetramethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added. As a resin binder, 100 g of an epoxy resin dissolved in MEK at a solid content of 30% by mass was added.

  The mixture was stirred with a paint shaker for 30 minutes to remove the steel beads, and a metal particle dispersion coating solution was prepared.

[Insulation evaluation]
A comb-type wiring pattern of wiring (L) / interval (S) = 80 μm / 80 μm was formed by etching the Cu-bonded substrate.

  Each metal particle dispersion coating solution obtained as described above was formed into a film with a thickness of 50 μm by an applicator, and a resistance value was measured by applying a DC voltage of 10 V between the wirings. The results are shown in Table 2.

  All of Comparative Examples 1 to 5 broke down instantaneously and could not be measured.

  The insulating coated metal particles obtained by the present invention are uniformly coated with a dense insulating film and excellent in insulating properties, and are suitably applied to fields such as semiconductor manufacturing, electronic component manufacturing, and printed circuit board manufacturing.

2 is a micrograph (SEM) showing the surface of insulating coated metal particles obtained in Example 1. FIG. 4 is a micrograph (SEM) showing the surface of insulating coated metal particles obtained in Example 3. FIG. 4 is a micrograph (SEM) showing the surface of untreated metal particles obtained in Comparative Example 1. It is a microscope picture (SEM) which shows the surface of the insulation coating metal particle which does not use the metal alkoxide obtained by the comparative example 2. It is a microscope picture (SEM) which shows the surface of the insulation coating metal particle which does not use the oxide sol obtained by the comparative example 3.

Claims (8)

  Using a metal organic compound capable of forming a hydroxyl group by hydrolysis, silica sol, titania sol, alumina sol is formed on the surface of the metal particle via —O—Me—O— bond (Me: metal contained in the metal organic compound). Insulating coated metal particles formed by coating a film derived from a metal oxide sol containing one or more selected from cerium oxide sol. The metal organic compound is Me (RO) _m (R) _n (where Me represents a metal element of Si, Ti, Zr, Al, R represents an alkyl group having 1 to 8 carbon atoms, m + n represents a number equal to the valence of Me, m represents a number of 2 or more, and n represents 0 or a number of 1 or more), or Me (RO) _m (Y) _n ( However, Me, R, m + n, m, and n are as defined above, respectively, and Y is a hydrocarbon group having 1 to 12 carbon atoms, an amino group, an epoxy group, a vinyl group, an acrylic group, and a methacryl group. The insulating coated metal particles according to claim 1, which is one or more selected from coupling agents represented by a selected organic functional group or alkyl acetate.   The insulation-coated metal particles according to claim 1 or 2, wherein the primary particle size of the metal oxide contained in the metal oxide sol is 5 to 100 nm.   The insulation coating metal particle according to any one of claims 1 to 3, wherein a secondary particle size of the metal oxide contained in the metal oxide sol is 200 nm or less.   Metal oxide in which metal particles are dispersed in a solvent and a hydroxyl group can be formed by hydrolysis, and a metal oxide containing one or more selected from silica sol, titania sol, alumina sol, and cerium oxide sol After stirring the solution to which the sol has been added, the pH of the solution is adjusted to 3 to 4 and stirred and allowed to stand, whereby the hydroxyl group formed by hydrolysis of the metal organic compound is converted into a metal oxide sol, or The hydrolysis / adsorption (bonding) step for adsorbing (binding) to the metal particles and the pH of the solution after the hydrolysis / adsorption (binding) step are maintained by changing the pH value by 2 or more with respect to pH 3-4. Thus, the dehydration / condensation reaction is promoted in a solution to form an —O—Me—O bond (Me: metal contained in the metal organic compound), and the —O—Me— A dehydration / condensation reaction accelerating step for adsorbing (bonding) the metal oxide sol to the metal particles through the bond, and a step of filtering, drying and heat-treating the solution after the dehydration / condensation reaction accelerating step. A method for producing insulating coated metal particles. The metal organic compound is Me (RO) _m (R) _n (where Me represents a metal element of Si, Ti, Zr, Al, R represents an alkyl group having 1 to 8 carbon atoms, m + n represents a number equal to the valence of Me, m represents a number of 2 or more, and n represents 0 or a number of 1 or more), or Me (RO) _m (Y) _n ( However, Me, R, m + n, m, and n are as defined above, respectively, and Y is a hydrocarbon group having 1 to 12 carbon atoms, an amino group, an epoxy group, a vinyl group, an acrylic group, and a methacryl group. The method for producing insulating coated metal particles according to claim 5, which is one or more selected from coupling agents represented by: an organic functional group selected or an alkyl acetate.   The manufacturing method of the insulation coating metal particle of Claim 5 or 6 whose primary particle size of the metal oxide contained in metal oxide sol is 5-100 nm.   The manufacturing method of the insulation coating metal particle of any one of Claims 5-7 whose secondary particle size of the metal oxide contained in metal oxide sol is 200 nm or less.