JP6961952B2 - Manufacturing method of molding material - Google Patents

Description

The present invention relates to a method for producing a surface-treated metal powder and a method for producing a molding material.

With the recent miniaturization and weight reduction of electronic devices, there is a demand for molding materials having high magnetic permeability and high moldability. Metal powder is known as a material having a high magnetic permeability.

In the molding material, a surface-treated additive component is blended in the resin in order to obtain desired properties. For example, Patent Document 1 discloses a method for producing a surface-treated boron nitride powder subjected to plasma treatment as the additive component in order to improve the adhesion to a resin as a matrix.

Japanese Unexamined Patent Publication No. 2015-137335

However, when the surface-treated additive component is blended with the resin, there is a problem that the fluidity as a molding material is lowered.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a surface-treated metal powder capable of enhancing fluidity when blended in a resin composition.

The present invention includes the following aspects.
[1] A step (i) in which the metal powder is dispersed in the air and the surface of the metal powder is uniformly subjected to plasma treatment.
The step (ii) of reacting the plasma-treated metal powder with the coupling agent in the step (i),
Step (I) of obtaining a surface-treated metal powder having
The step (II) of mixing the surface-treated metal powder obtained in the step (I) with the resin, and
It is a manufacturing method of a molding material having
The resin is selected from the group consisting of a triphenylmethane type epoxy resin, a dicyclopentadiene type epoxy resin, a bisphenol A type epoxy resin, a tetramethylbisphenol F type epoxy resin, a biphenyl aralkyl type phenol resin, and a novolak type phenol resin. A method for producing a molding material , which comprises one or more kinds of resins.
[2 ] The method for producing a molding material according to [1], wherein the step (i) includes an operation of applying an _{O 2 plasma treatment to the metal powder.}

[ 3 ] The method for producing a molding material according to [2 ], wherein the step (i) includes an operation of applying an Ar plasma treatment to the metal powder before the operation of performing the _{O 2 plasma treatment.}
[ 4 ] In the step (ii), the metal powder immediately after the plasma treatment in the step (i) is immersed in a solution of the coupling agent, or the metal powder is dipped in the coupling agent or a cup. The method for producing a molding material according to any one of [1] to [3 ], which comprises an operation of directly spraying a ring agent diluted solution to react the metal powder with the coupling agent.
[ 5 ] One of [1] to [4 ], wherein the metal constituting the metal powder contains at least one selected from the group consisting of iron, chromium, cobalt, nickel, silver, and manganese. The method for producing a molding material according to the description.

[ 6 ] Production of the molding material according to [5 ], wherein the metal powder is at least one selected from the group consisting of pure iron, silicon steel, iron-cobalt alloy, iron-nickel alloy, and carbonyl iron. Method.
[ 7 ] The molding material according to any one of [1] to [6 ], wherein the coupling agent is at least one selected from the group consisting of a silane-based coupling agent and a titanium-based coupling agent. Manufacturing method.

According to the method for producing a surface-treated metal powder of the present invention, it is possible to provide a surface-treated metal powder that can enhance the fluidity when blended in a resin composition. Further, according to the method for producing a molding material of the present invention, it is possible to provide a molding material having high magnetic permeability and high formability and degree of freedom in shape.

It is a schematic diagram of the surface-treated metal powder of one embodiment.

[Manufacturing method of surface-treated metal powder]
The method for producing the surface-treated metal powder of the present embodiment is a step (i) of subjecting the metal powder to plasma treatment and a step of reacting the metal powder treated with plasma in the step (i) with a coupling agent ( ii) and.
The surface treatment refers to an operation for modifying the surface of the metal powder.

(Step (i))
Examples of the plasma treatment include O ₂ plasma treatment, Ar plasma treatment, N ₂ plasma and the like. By performing the plasma treatment, it is possible to modify the surface of the metal powder and remove stains on the surface of the metal powder.

The pressure of the plasma treatment is preferably 10 to 200 Pa, more preferably 15 to 180 Pa. The flow rate of the plasma treatment is preferably 10 to 5000 mL / min, more preferably 20 to 4000 mL / min. The output of the plasma treatment is preferably 100 to 500 W, more preferably 200 to 400 W. The treatment time of the plasma treatment is preferably 5 to 60 minutes, more preferably 10 to 40 minutes.

The step (i) preferably includes an operation of uniformly applying plasma treatment to the surface of the metal powder. As a result, active sites capable of reacting with the coupling agent can be uniformly formed on the surface of the metal powder.

The uniform plasma treatment means that the metal powder is dispersed in the air and plasma-treated.

The step (i) preferably includes an operation of applying _{O 2 plasma treatment to the metal powder. By performing O 2} plasma treatment on the metal powder as the main treatment, OH groups are generated on the surface of the metal powder, and the metal powder and the residue of the coupling agent can be bonded via oxygen atoms. can. As a result, the coupling agent can be firmly bonded to the surface of the metal powder.

The pressure of the O ₂ plasma treatment is preferably 100 to 200 Pa, more preferably 120 to 180 Pa. The flow rate of the O ₂ plasma treatment is preferably 1000 to 5000 mL / min, more preferably 2000 to 4000 mL / min. The output of the O ₂ plasma treatment is preferably 100 to 500 W, more preferably 200 to 400 W. The treatment time of the O ₂ plasma treatment is preferably 5 to 60 minutes, more preferably 10 to 40 minutes.

The step (i) preferably includes an operation of applying Ar plasma treatment to the metal powder before the operation of applying the _{O 2 plasma treatment.} By performing Ar plasma treatment on the metal powder as a pretreatment, active spots capable of modifying OH groups can be formed on the surface of the metal powder.

The pressure of the Ar plasma treatment is preferably 10 to 100 Pa, more preferably 15 to 80 Pa. The flow rate of the Ar plasma treatment is preferably 10 to 100 mL / min, more preferably 20 to 80 mL / min. The output of the Ar plasma treatment is preferably 100 to 500 W, more preferably 200 to 400 W. The treatment time of the Ar plasma treatment is preferably 5 to 60 minutes, more preferably 10 to 40 minutes.

(Process (ii))
The amount of the coupling agent used is preferably in the range of 0.05 to 1 part, and more preferably in the range of 0.1 to 0.5 part with respect to 100 parts of the metal powder on a weight basis. preferable.

The reaction temperature in the step (ii) is preferably 20 to 80 ° C. The reaction time in the step (ii) is preferably 1 to 24 hours.

In the step (ii), it is preferable to react the metal powder immediately after the plasma treatment in the step (i) with the coupling agent. As the method, for example, the metal powder immediately after the plasma treatment in the step (i) is immersed in a diluted solution of the coupling agent, or the metal powder is mixed with the coupling agent or the diluted solution of the coupling agent. A method of spraying directly can be mentioned.

By reacting the metal powder immediately after the plasma treatment in the step (i) with the coupling agent, the reaction proceeds more and the surface of the metal powder is more easily modified.

Immediately after the plasma treatment is applied, it means a range from 0 to 24 hours after the plasma treatment is applied.

Examples of the solvent for the solution of the coupling agent include methanol, ethanol, isopropyl alcohol and the like. The amount of the coupling agent used is preferably in the range of 0.1 to 2 parts and more preferably in the range of 0.5 to 1.5 parts with respect to 100 parts of the solvent on a weight basis. ..

The immersion time in the step (ii) is preferably 1 to 24 hours.

The average particle size of the metal powder is preferably 1 to 180 μm, more preferably 3 to 150 μm, even more preferably 3 to 100 μm, and even more preferably 5 to 50 μm.

When the average particle size of the metal powder is 1 to 180 μm, the fluidity of the surface-treated metal powder when blended in the resin composition can be enhanced. When the average particle size of the metal powder is 1 μm or more, molding becomes easy. When the average particle size of the metal powder is 180 μm or less, it is difficult to settle and molding becomes easy.

The average particle size means a volume average particle size, and can be measured by a laser diffraction type particle size distribution measuring device.

The sphericity of the metal powder is preferably 0.60 to 1.00, more preferably 0.70 to 1.00.

When the sphericity of the metal powder is 0.60 to 1.00, the fluidity of the surface-treated metal powder when blended in the resin composition can be enhanced.

The sphericity can be obtained from the SEM image of the particles by the diameter equivalent to the circle of the area / the diameter of the circumscribed circle.

Examples of the metal constituting the metal powder include iron, chromium, cobalt, nickel, silver, manganese, copper and vanadium. From the viewpoint of improving the magnetic properties (permeability), it is more preferable that the metal constituting the metal powder contains at least one selected from the group consisting of iron, chromium, cobalt, nickel, silver, and manganese.

Examples of the metal powder include pure iron, silicon steel, iron-cobalt alloy, iron-nickel alloy, carbonyl iron, and stainless steel. From the viewpoint of improving the magnetic properties (magnetic permeability), the metal powder may be one or more selected from the group consisting of pure iron, silicon steel, iron-cobalt alloy, iron-nickel alloy, and carbonyl iron. More preferred.

Examples of the coupling agent include a silane-based coupling agent, a titanium-based coupling agent, a zirconia-based coupling agent, an aluminum-based coupling agent, and the like.

Of these, the coupling agent is preferably one or more selected from the group consisting of silane-based coupling agents and titanium-based coupling agents. Thereby, the fluidity of the surface-treated metal powder when blended in the resin composition can be enhanced.

According to the above-mentioned production method, it is possible to efficiently produce a surface-treated metal powder that can enhance the fluidity when blended in the resin composition.

[Structure of surface-treated metal powder]
FIG. 1 shows an example of a complex contained in the surface-treated metal powder produced by the above-mentioned production method.

In the complex (10) shown in FIG. 1, a functional group represented by −OX-R (general formula (1)) is bonded to the surface (100S) of the metal particles (100). The surface-treated metal powder contains a complex (10) in which metal particles (100) and functional groups are bonded.

* -O-X-R ... (1)
In the formula, R represents an organic group, X is Si, Ti, Al, or Zr, and * is one of the atoms constituting the metal particles.

More specifically, the O ₂ plasma treatment in the above method produces OH groups on the surface of the metal particles, and as described above, the metal particles and the residue of the coupling agent are bonded via oxygen atoms. be able to. As a result, the coupling agent can be firmly bonded to the surface of the metal powder.

In the complex contained in the surface-treated metal powder described above, it can be confirmed by a Fourier transform infrared spectrophotometer that the metal particles and the residue of the coupling agent are bonded via oxygen atoms. can.

The functional group is preferably a residue of a coupling agent selected from the group consisting of a silane-based coupling agent and a titanium-based coupling agent. By selecting either the silane-based coupling agent or the titanium-based coupling agent, the fluidity of the surface-treated metal powder when blended in the resin composition can be enhanced.

[Characteristics of surface-treated metal powder]
Next, an example of the characteristics of the surface-treated metal powder obtained by the above-mentioned production method will be described.
One of the characteristics of the surface-treated metal powder is that it satisfies the following viscosity ratio (thixo ratio) when blended in a resin composition containing an epoxy resin, a phenol resin, and a solvent.
Viscosity when the shear shear rate of the viscoelasticity measuring device is 1 / viscosity when the shearing shear rate of the viscoelasticity measuring device is 10 when the temperature condition is 30 ° C. <3.4

As the epoxy resin, a polycondensate of allylated bisphenol A and epichlorohydrin is used, and as the phenol resin, a 2-allylphenol formaldehyde polycondensate is used.

The amount of the surface-treated metal powder used is in the range of 15 to 50 parts with respect to a total of 100 parts of the resin on a volume basis.

The amount of the epoxy resin used is in the range of 30 to 60% by volume in the resin composition, and the amount of the phenol resin used is in the range of 10 to 30% by volume in the resin composition. The total amount of the epoxy resin and the phenol resin used is in the range of 50 to 85% by volume in the resin composition.

Examples of the solvent used in the resin composition include butyl cellosolve acetate and 1-methoxy-2-propanol.

The viscosity ratio (thixo ratio) is less than 3.4, preferably 1.5 or more and less than 3.4, more preferably 2.0 or more and 3.0 or less, and 2.1 or more and 3 It is even more preferably less than .0, and even more preferably 2.2 or more and 2.8 or less. When the viscosity ratio (thixo ratio) is 1.5 or more and less than 3.4, the fluidity of the surface-treated metal powder when blended in the resin composition can be enhanced.

The viscosity is measured by a viscoelasticity measuring device (“RheoStress RS” manufactured by HAAKE Co., Ltd.
150 ”) can be used to measure the resin composition by applying shear shear between a gap of 50 to 1000 μm in a parallel plate of 20 mmφ.

Since the above-mentioned surface-treated metal powder satisfies a predetermined viscosity ratio (thixo ratio), the fluidity of the surface-treated metal powder when blended in the resin composition can be enhanced.

To be less than 3.4 the viscosity ratio, for example, a method of applying an O ₂ plasma treatment or coupling treatment. Among them, _{it is preferable to perform both O 2} plasma treatment and coupling treatment on the metal powder, and the coupling agent is selected from the group consisting of a silane-based coupling agent and a titanium-based coupling agent. Is more preferable.

[Manufacturing method of molding material]
The method for producing the molding material of the present embodiment is a step (I) of obtaining a surface-treated metal powder by the above-mentioned manufacturing method and a step (II) of mixing the surface-treated metal powder obtained in the step (I) with a resin. ) And. The molding material obtained by this production method is a metal filler-containing resin material, which has high magnetic permeability and high moldability. In addition, since it has excellent fluidity, it has a high degree of freedom in shape.

Examples of the resin include epoxy resin, phenol resin, maleimide resin, benzoxazine, cyanate resin, acrylic resin and the like. Of these, epoxy resins and phenol resins are preferred.

The resin contains one or more solid epoxy resins selected from the group consisting of triphenylmethane type epoxy resin, dicyclopentadiene type epoxy resin, bisphenol A type epoxy resin, and tetramethylbisphenol F type epoxy resin. Is preferable. By containing any of the above epoxy resins, it is possible to obtain a material having high heat resistance and suitable for transfer molding.

The resin preferably contains one or more solid phenol resins selected from the group consisting of biphenyl aralkyl type phenol resins and novolak type phenol resins. By containing any of the above phenolic resins, it is possible to obtain a material having high heat resistance and suitable for transfer molding.

The molding material obtained by the production method of the present embodiment may contain other components in addition to the surface-treated metal powder and resin obtained by the above-mentioned production method. Examples of other components include solvents, mold release agents, curing accelerators, adhesion aids, colorants, antioxidants, anticorrosions and the like.

Examples of applications of the molding material obtained by the manufacturing method of the present embodiment include automobile reactors, inductors, motor magnet fixing materials, and the like.

According to the manufacturing method described above, it is possible to provide a molding material having a high magnetic permeability and a high degree of moldability and shape freedom.

Hereinafter, the effects of the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Preparation of surface-treated metal powder]
A surface-treated metal powder was prepared as shown below.

(Example 1)
[Step (i)]
Using a rotary tabletop vacuum plasma device (YHS-DΦS manufactured by Kaoru Semiconductor Co., Ltd.), pure iron powder (1000 g, manufactured by Kobe Steel Co., Ltd., ML35N, volume average particle diameter D ₅₀ = 180 μm, spherical shape Pretreatment (gas type Ar, pressure 20 Pa, flow rate 50 mL / min, output 300 W, treatment time 40 minutes) was carried out with Ar plasma against the degree 0.75). Next, using the same device, O ₂ plasma treatment (gas type H ₂ O bubbling / O ₂ , pressure 150 Pa, flow rate 3000 mL / min, output 300 W, treatment time 40 minutes) was carried out.

[Process (ii)]
Immediately after the completion of O ₂ plasma treatment, that is, _{5 minutes after O 2} plasma treatment, silane-based coupling agent (0.3 g, manufactured by Shin-Etsu Chemical Co., Ltd., KBM303) and ethanol. It was immersed in the solution of (20 g) and stirred with a shaker overnight. Then, the solid content was separated by a centrifuge, washed with ethanol three times, and dried at 85 ° C. for 2 hours to obtain a surface-treated metal powder of Example 1.

(Example 2)
Same as Example 1 except that a titanium-based coupling agent (0.3 g, manufactured by Ajinomoto Fine-Techno Co., Ltd., Plenact 9SA) was used instead of the silane-based coupling agent, and isopropyl alcohol was used instead of ethanol. The surface-treated metal powder of Example 2 was obtained.

(Comparative Example 1)
Pure iron powder (20 g, manufactured by Kobe Steel, Ltd., ML35N, volume average particle size D ₅₀ = 180 μm, sphericity 0.75), silane coupling agent (0.3 g, Shin-Etsu Chemical Co., Ltd.) It was immersed in a solution of KBM303) manufactured by Shin-Etsu Chemical Co., Ltd. and ethanol (20 g), and stirred overnight with a shaker. Then, the solid content was separated by a centrifuge, washed with ethanol three times, and dried at 85 ° C. for 2 hours to obtain a surface-treated metal powder of Comparative Example 1.

(Comparative Example 2)
Comparative example except that a titanium-based coupling agent (0.3 g, manufactured by Ajinomoto Fine-Techno Co., Ltd., Plenact 9SA) was used instead of the silane-based coupling agent "KBM303", and isopropyl alcohol was used instead of ethanol. The surface-treated metal powder of Comparative Example 2 was produced in the same manner as in 1.

(Comparative Example 3)
Using a rotary tabletop vacuum plasma device (YHS-DΦS manufactured by Kaoru Semiconductor Co., Ltd.), pure iron powder (1000 g, manufactured by Kobe Steel Co., Ltd., ML35N, volume average particle diameter D ₅₀ = 180 μm, spherical shape Pretreatment (gas type Ar, pressure 20 Pa, flow rate 50 mL / min, output 300 W, treatment time 40 minutes) was carried out with Ar plasma against the degree 0.75). Next, using the same device, O ₂ plasma treatment (gas type H ₂ O bubbling / O ₂ , pressure 150 Pa, flow rate 3000 mL / min, output 300 W, treatment time 40 minutes) was carried out to perform surface treatment of Comparative Example 3. Obtained metal powder.

(Comparative Example 4)
Pure iron powder (20 g, manufactured by Kobe Steel, Ltd., ML35N, volume average particle diameter D ₅₀ = 180 μm, sphericity 0.75) was used as it was as a metal powder.

[Evaluation of viscosity ratio (Chixo ratio)]
The surface-treated metal powder (13.0 g) of Example 1, the epoxy resin (manufactured by Nippon Kayaku Co., Ltd., RE-810NM, 1.4 g), and the phenol resin (manufactured by Meiwa Kasei Co., Ltd., MEH-). A mixture (paste) with 8000H, 0.6 g) was prepared.

Then, at 30 ° C., the mixture was set in a viscoelasticity measuring device, and the shear viscosity when the upper cone was rotated to give strain was measured. The viscosities when the shear shear rates of the viscoelasticity measuring devices were set to 1 and 10, respectively, were measured, and the ratio between the two was taken to obtain the viscosity ratio (thixo ratio).

Examples 2 and Comparative Examples 1 to 4 were also evaluated in the same manner as in Example 1 to obtain a viscosity ratio (thixo ratio). These results are shown in Table 1.

As shown in Table 1, the metal powders (Examples 1 and 2) subjected to both the plasma treatment and the coupling treatment (silane-based coupling agent or titanium-based coupling agent) have a viscosity ratio (thixo ratio) of 3. It was less than 0.4.
On the other hand, the metal powder (Comparative Examples 1 to 3) in which only one of the plasma treatment and the coupling treatment was carried out and the metal powder in which both were not carried out (Comparative Example 4) had a viscosity ratio (thixo ratio) of 3. It became 4 or more.

[Evaluation of spiral flow]
Epoxy resin (manufactured by Mitsubishi Chemical Corporation, YL6810, 3.28% by weight), epoxy resin (manufactured by Nippon Kayaku Co., Ltd., NC-3000, 5.15% by weight), and phenol resin (Japaneseized) Yakuhin Co., Ltd., KAYAHARD GPH-65, 7.56% by weight), mold release agent (Clariant Japan Co., Ltd., Recolve WE-4, 0.33% by weight), and curing accelerator (Shikoku) A mixture of Curesol 2PZ-PW (0.28% by weight) manufactured by Kasei Kogyo Co., Ltd. and the surface-treated metal powder (83.40% by weight) of Example 1 was obtained.

Next, using a low-pressure transfer molding machine (“KST-30” manufactured by Kotaki Seiki Co., Ltd.), a mold for measuring spiral flow according to EMMI-1-66 was charged with a mold temperature of 175 ° C. and an injection pressure of 6.9 MPa. , The spiral flow value of the mixture was measured under the condition of holding pressure time of 120 seconds.

Examples 2 and Comparative Examples 1, 2 and 4 were also measured in the same manner as in Example 1 to obtain a spiral flow value.

(Comparative Example 5)
Epoxy resin (manufactured by Mitsubishi Chemical Corporation, YL6810, 3.28% by weight), epoxy resin (manufactured by Nippon Kayaku Co., Ltd., NC-3000, 5.15% by weight), phenol resin (Nippon Kayaku (Nippon Kayaku) KAYAHARD GPH-65, 7.56% by weight), mold release agent (Clariant Japan Co., Ltd., Recolve WE-4, 0.33% by weight), curing accelerator (Shikoku Kasei Kogyo Co., Ltd.) ), Curesol 2PZ-PW, 0.28% by weight), pure iron powder (20 g, manufactured by Kobe Steel Co., Ltd., ML35N, volume average particle size D ₅₀ = 180 μm, sphericality 0.75, 83. 39% by weight) and a silane coupling agent (0.01 g, manufactured by Shin-Etsu Chemical Co., Ltd., KBM303) were prepared.

Next, using a low-pressure transfer molding machine (“KST-30” manufactured by Kotaki Seiki Co., Ltd.), a mold for measuring spiral flow according to EMMI-1-66 was charged with a mold temperature of 175 ° C. and an injection pressure of 6.9 MPa. , The spiral flow value of the mixture was measured under the condition of holding pressure time of 120 seconds.

(Comparative Example 6)
A mixture was prepared in the same manner as in Comparative Example 5 except that a titanium-based coupling agent (0.01 g, manufactured by Ajinomoto Fine-Techno Co., Ltd., Plenact 9SA) was used instead of the silane-based coupling agent, and a spiral flow was prepared. The value was measured.

These results are shown in Table 2.

As shown in Table 2, the metal powders (Examples 1 and 2) subjected to both the plasma treatment and the coupling treatment (silane-based coupling agent or titanium-based coupling agent) were subjected to only the coupling treatment. The spiral flow value was higher than that of the metal powder (Comparative Examples 1, 2, 5 and 6) and the metal powder in which both were not carried out (Comparative Example 4).

Further, the metal powder obtained by coupling the metal powder immediately after the plasma treatment (Examples 1 and 2) has a higher spiral flow value than the metal powder (Examples 5 and 6) to which the coupling agent is post-added. became.

Therefore, according to the method for producing a surface-treated metal powder of the present invention, it is possible to provide a surface-treated metal powder that can enhance the fluidity when blended in a resin composition.

The production method of the present invention can provide a surface-treated metal powder that can enhance the fluidity when blended in a resin composition. The surface-treated metal powder obtained by such a manufacturing method can be suitably used as a reactor, an inductor, a motor magnet fixing material, or the like for an automobile.

10 ... Surface-treated metal powder, 100 ... Metal powder, 100S ... Surface of metal powder

Claims (7)

The step (i) of dispersing the metal powder in the air and uniformly applying plasma treatment to the surface of the metal powder,
The step (ii) of reacting the plasma-treated metal powder with the coupling agent in the step (i),
Step (I) of obtaining a surface-treated metal powder having
The step (II) of mixing the surface-treated metal powder obtained in the step (I) with the resin, and
It is a manufacturing method of a molding material having
The resin is selected from the group consisting of a triphenylmethane type epoxy resin, a dicyclopentadiene type epoxy resin, a bisphenol A type epoxy resin, a tetramethylbisphenol F type epoxy resin, a biphenyl aralkyl type phenol resin, and a novolak type phenol resin. A method for producing a molding material , which comprises one or more kinds of resins. The method for producing a molding material according to claim 1, wherein the step (i) includes an operation of applying an _{O 2 plasma treatment to the metal powder.} The method for producing a molding material according to claim 2 , wherein the step (i) includes an operation of applying Ar plasma treatment to the metal powder before the operation of applying the _{O 2 plasma treatment.} In the step (ii), the metal powder immediately after the plasma treatment in the step (i) is immersed in a solution of the coupling agent, or the metal powder is dipped in the coupling agent or the coupling agent. The method for producing a molding material according to any one of claims 1 to 3 , which comprises an operation of directly spraying the solution to react the metal powder with the coupling agent. The molding material according to any one of claims 1 to 4 , wherein the metal constituting the metal powder contains at least one selected from the group consisting of iron, chromium, cobalt, nickel, silver, and manganese. Production method. The method for producing a molding material according to claim 5 , wherein the metal powder is at least one selected from the group consisting of pure iron, silicon steel, iron-cobalt alloy, iron-nickel alloy, and carbonyl iron. The method for producing a molding material according to any one of claims 1 to 6 , wherein the coupling agent is at least one selected from the group consisting of a silane-based coupling agent and a titanium-based coupling agent.

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