JP7206615B2 - Molding materials and moldings - Google Patents

Description

The present invention relates to molding materials and molded articles.

In recent years, as electronic devices have become smaller and lighter, molding materials with high magnetic permeability and high moldability are required.

Examples of such molding materials include materials containing magnetic metal powder and resin. In such a molding material, it is required to enhance the adhesion between the inorganic powder such as the magnetic metal powder and the resin.

Therefore, Patent Literature 1 discloses subjecting the particle surfaces of the inorganic powder to plasma treatment in order to improve the adhesion between the inorganic powder and the resin as a matrix.

JP 2015-137335 A

However, a molding material obtained by mixing plasma-treated inorganic powder and resin has a problem of low fluidity.

Moreover, in such a molding material, the inorganic powder and the resin are easily separated. For this reason, there is a concern that the separated resin may leak into an unintended region of the mold during molding, causing problems (for example, resin burrs on the molded body).

An object of the present invention is to provide a molding material that achieves both high fluidity during molding and suppression of resin exudation, and to provide a molded article that has good magnetic properties and little molding defects.

Such objects are achieved by the present invention of the following (1) to (11).

(1) a resin;
a magnetic powder containing first particles exhibiting soft magnetism and having an iron content of 85% by mass or more;
a non-magnetic powder exhibiting non-magnetism and having an average particle size of 3 μm or less and smaller than the magnetic powder;
A molding material characterized by having

(2) The molding material according to (1) above, wherein the constituent material of the non-magnetic powder contains a ceramic material.

(3) The molding material according to (2) above, wherein the ceramic material contains silica.

(4) The molding material according to any one of (1) to (3) above, wherein the magnetic powder further includes second particles whose constituent material composition is different from that of the first particles.

(5) The molding material according to (4) above, wherein the first particles and the second particles have different average particle sizes.

(6) The molding material according to (5) above, wherein the average particle size of the second particles is 1 to 100 μm smaller than the average particle size of the first particles.

(7) The molding material according to any one of (1) to (6) above, wherein the average particle diameter of the first particles is 10 to 200 μm.

(8) The molding material according to any one of (1) to (7) above, wherein the magnetic powder has a volume fraction of 50 to 90% by volume.

(9) The molding material according to any one of (1) to (8) above, wherein the volume fraction of the nonmagnetic powder is 3 to 25% by volume of the magnetic powder.

(10) A molded article which is a cured product of the molding material according to any one of (1) to (9) above.

(11) The compact according to (10) above, which has a relative magnetic permeability of 10 or more.

ADVANTAGE OF THE INVENTION According to this invention, the molding material which can make high fluidity|liquidity at the time of molding compatible, and suppression of the bleeding of resin is obtained.

Further, according to the present invention, a molded article having good magnetic properties and less molding defects can be obtained.

It is a figure which shows embodiment of the molding material of this invention. FIG. 2 is a cross-sectional view of one particle contained in the magnetic powder shown in FIG. 1, and is a conceptual diagram showing an example of surface treatment.

BEST MODE FOR CARRYING OUT THE INVENTION The molding material and molded article of the present invention will be described in detail below based on preferred embodiments shown in the accompanying drawings.
<Molding material>
First, an embodiment of the molding material of the present invention will be described.

FIG. 1 is a diagram showing an embodiment of the molding material of the present invention. Note that FIG. 1 shows the included elements by symbols, and the type of each symbol has no particular meaning.

The molding material 1 shown in FIG. 1 has resin 2 , magnetic powder 3 containing first particles 31 and second particles 32 , and non-magnetic powder 4 . Such a molding material 1 can be molded by various molding methods to produce a molded article having a desired shape. Such compacts exhibit soft magnetism and are used as magnetic elements such as dust cores. Each element of the molding material 1 will be described in detail below.

(resin)
The resin 2 is prepared, for example, in a semi-cured (solid) state. Such a resin 2 is melted by being heated and pressurized during molding, and hardens while being molded into a desired shape. As a result, a molded article that takes advantage of the properties of the resin can be obtained.

Examples of the resin 2 include thermosetting resins, thermoplastic resins, and mixtures thereof. By including a thermosetting resin in the resin 2, the mechanical properties of the cured product of the molding material 1 can be easily improved. In addition, since the resin 2 contains a thermoplastic resin, the stress of the cured product of the molding material 1 can be reduced, and deformation of the cured product can be suppressed.

Thermosetting resins include, for example, novolak-type phenolic resins such as phenol novolak resin, cresol novolak resin, bisphenol A-type novolac resin, triazine skeleton-containing phenol novolak resin; unmodified resol phenol resin, tung oil, linseed oil, and walnut oil. Phenol resins such as resol type phenol resins such as oil-modified resol phenol resins, phenol aralkyl resins, and aralkyl type phenol resins such as biphenyl aralkyl type phenol resins; bisphenol A type epoxy resins, bisphenol F type epoxy resins, tetramethyl Bisphenol type epoxy resins such as bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol E type epoxy resin, bisphenol M type epoxy resin, bisphenol P type epoxy resin, bisphenol Z type epoxy resin; phenol novolak type epoxy resin, cresol novolak novolak type epoxy resins such as type epoxy resins; biphenyl type epoxy resins, biphenyl aralkyl type epoxy resins, arylalkylene type epoxy resins, naphthalene type epoxy resins, anthracene type epoxy resins, phenoxy type epoxy resins, dicyclopentadiene type epoxy resins, norbornene type epoxy resin, adamantane type epoxy resin, fluorene type epoxy resin, triphenylmethane type epoxy resin; urea (urea) resin, resin having a triazine ring such as melamine resin; unsaturated polyester resin; bismaleimide compound, etc. Maleimide resin; polyurethane resin; diallyl phthalate resin; silicone resin; benzoxazine resin; polyimide resin; polyamideimide resin; Examples include cyanate ester resins such as cyanate resins such as bisphenol F type cyanate resins. As the thermosetting resin, one of these may be used alone, or two or more of them having different weight average molecular weights may be used in combination. A prepolymer may be used in combination.

Among these, as the thermosetting resin, one containing an epoxy resin or a phenol resin is preferably used.

The thermosetting resin is one or more solid epoxy resins selected from the group consisting of triphenylmethane type epoxy resins, dicyclopentadiene type epoxy resins, bisphenol A type epoxy resins, and tetramethylbisphenol F type epoxy resins. It preferably contains a resin. According to the resin 2 containing such a thermosetting resin, the molding material 1 having high heat resistance and suitable for molding can be obtained.

Moreover, the thermosetting resin preferably contains one or more solid phenolic resins selected from the group consisting of biphenylaralkyl-type phenolic resins and novolac-type phenolic resins. According to the resin 2 containing such a thermosetting resin, the molding material 1 having high heat resistance and suitable for molding can be obtained.

In addition, a thermosetting resin is used together with a hardening|curing agent as needed.

When the thermosetting resin contains a novolac-type phenol resin, hexamethylenetetramine, for example, is used as the curing agent.

When the thermosetting resin contains an epoxy resin, the curing agent may be, for example, an aliphatic polyamine, an aromatic polyamine, an amine compound such as dicyaminediamide, an alicyclic acid anhydride, an aromatic acid anhydride, or the like. Acid anhydrides, polyphenol compounds such as novolac type phenol resins, imidazole compounds, and the like are used.

Moreover, when the thermosetting resin contains a maleimide resin, for example, an imidazole compound is used as the curing agent.

Examples of thermoplastic resins include acrylic resins, polyamide resins (e.g. nylon), thermoplastic urethane resins, polyolefin resins (e.g. polyethylene, polypropylene, ethylene copolymers, etc.), polycarbonates, polyester resins ( Polyethylene terephthalate, polybutylene terephthalate, etc.), polyacetal, polyphenylene sulfide, polyether ether ketone, liquid crystal polymer, fluororesin (e.g., polytetrafluoroethylene, polyvinylidene fluoride, etc.), modified polyphenylene ether, polysulfone, polyether sulfone, poly Arylate, polyamideimide, polyetherimide, thermoplastic polyimide, and the like. In the molding material 1, one of these may be used alone, or two or more of them having different weight average molecular weights may be used in combination. and may be used together.

Among these, as the thermoplastic resin, one containing an ethylene copolymer is preferably used. Ethylene-based copolymers have the property of having high affinity for metals. Therefore, the dispersibility of the magnetic powder 3 and the non-magnetic powder 4 in the molding material 1 can be enhanced by including the ethylene-based copolymer in the resin 2 . As a result, the homogeneity of the molding material 1 can be enhanced, and the mechanical strength of the cured product can be enhanced.

Ethylene copolymers include, for example, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl acrylate copolymer, vinyl chloride-vinyl acetate copolymer. , ethylene - (meth) acrylic acid copolymer, ethylene - methyl (meth) acrylate copolymer, ethylene - methyl acrylate copolymer, ethylene - ethyl acrylate copolymer, etc., among these One type or two or more types are used together.

Among these, thermoplastic resins are particularly ethylene-vinyl acetate copolymer (EVA), ethylene-methyl acrylate copolymer (EMA), ethylene-methyl methacrylate copolymer (EMMA), and ethylene-ethyl acrylate. It is more preferably at least one selected from the group consisting of copolymers (EEA), and at least one of ethylene-methyl acrylate copolymer (EMA) and ethylene-methyl methacrylate copolymer (EMMA). is more preferred.

The ethylene-based copolymer contains ethylene and a vinyl group having a polar group as monomer units. The ratio of vinyl groups having a polar group in the ethylene copolymer is preferably 5 to 50% by mass, more preferably 10 to 45% by mass, of the total mass of the ethylene copolymer. If the ratio of the vinyl group having a polar group is less than the above lower limit, the dispersibility of the magnetic powder 3 and the non-magnetic powder 4 in the molding material 1 may deteriorate. On the other hand, if the ratio of the vinyl group having a polar group exceeds the above upper limit, for example, when the ethylene copolymer is used in combination with the thermosetting resin, there is a possibility that the affinity between the two will be lowered.

Moreover, the ethylene-based copolymer may contain other monomer units.

Other monomeric units include, for example, α-olefins such as ethylene, propylene, n-butene and isobutylene; acrylic acid and its salts; methyl acrylate, ethyl acrylate,
Acrylic esters such as n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate; methacrylic acid and its salts; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, methacrylic acid esters such as dodecyl methacrylate and octadecyl methacrylate; its acid salt or its quaternary salt, acrylamide derivatives such as N-methylolacrylamide and its derivatives; or an acid salt thereof or a quaternary salt thereof, methacrylamide derivatives such as N-methylol methacrylamide or derivatives thereof; methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, vinyl ethers such as t-butyl vinyl ether, dodecyl vinyl ether and stearyl vinyl ether; nitriles such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride and vinyl fluoride; vinylidene halides such as vinylidene chloride and vinylidene fluoride; allyl compounds such as allyl and allyl chloride; maleic acid and its salts or its esters or its anhydrides; vinylsilyl compounds such as vinyltrimethoxysilane; Used together. The content of such other monomer units is preferably 10 mass % or less, more preferably 0.1 to 5 mass % of the ethylene copolymer.

In addition, the ethylene copolymer may have functional groups such as hydroxyl groups, carboxyl groups, acid anhydride groups, amino groups and trimethoxysilyl groups in the molecular chains or at the ends of the molecular chains.

Furthermore, the ethylene-based copolymer described above may be a saponified product thereof. This saponified product is obtained by saponifying an ethylene copolymer with an alkali metal compound such as sodium hydroxide, potassium hydroxide, sodium alkoxide and potassium alkoxide.

On the other hand, the resin 2 preferably contains both a thermosetting resin and a thermoplastic resin. As a result, it is possible to improve the mechanical properties of the cured product of the molding material 1 and reduce the stress of the cured product. As a result, for example, it is possible to realize a magnetic element that has high mechanical strength and that is resistant to deformation, cracking, and the like.

In this case, the content of the thermoplastic resin in the resin 2 is not particularly limited, but is preferably 1 to 50% by mass, more preferably 5 to 40% by mass. When the content of the thermoplastic resin is below the lower limit, the stress of the cured product of the molding material 1 can be sufficiently reduced depending on the type of thermosetting resin contained in the resin 2 and the blending ratio of the resin 2. may not be possible. On the other hand, if the content of the thermoplastic resin exceeds the upper limit, the moldability of the molding material 1 may deteriorate depending on the type of thermosetting resin contained in the resin 2 and the blending ratio of the resin 2.

The glass transition temperature Tg of the cured product of the molding material 1 is not particularly limited, but is preferably 150° C. or higher, more preferably 170° C. or higher, and even more preferably 190° C. or higher. By using such a molding material 1, it is possible to obtain a molding material 1 capable of producing a molded article suitable for use in a high-temperature environment.

The glass transition temperature Tg of the molding material 1 is measured by, for example, a thermomechanical analyzer (manufactured by Seiko Instruments Inc., TMA100).

The mass fraction of such resin 2 is preferably 2 to 10 mass %, more preferably 3 to 8 mass %, of the molding material 1 . As a result, the content of the resin 2 is optimized, so that the molding material 1 that can achieve both high fluidity during molding and suppression of resin exudation can be obtained.

In addition, when the resin 2 is used together with a curing agent, the mass fraction of the resin 2 is calculated including the mass of the curing agent.

(Magnetic powder)
The magnetic powder 3 contains the first particles 31 and the second particles 32 as described above.

Among these, the first particles 31 are particles exhibiting soft magnetism and having an iron content of 85% by mass or more.

Soft magnetism refers to ferromagnetism with a small coercive force. In general, ferromagnetism with a coercive force of 800 A/m or less is called soft magnetism.

As a constituent material of the first particles 31, a metal material having an iron content of 85% by mass or more as a constituent element can be used. A metal material having a high content of iron as a constituent element in this way exhibits soft magnetism with relatively good magnetic properties such as magnetic permeability and magnetic flux density. Therefore, a molding material that can exhibit good magnetic properties when molded into a powder magnetic core, for example, can be obtained.

Moreover, examples of the form of this metal material include, in addition to simple substances, alloys such as solid solutions, eutectics, and intermetallic compounds. By using the first particles 31 made of such a metal material, it is possible to obtain the molding material 1 having excellent magnetic properties derived from iron, that is, magnetic properties such as high magnetic permeability and high magnetic flux density. .

Moreover, the metal material may contain an element other than iron as a constituent element. Elements other than iron include, for example, B, C, N, O, Al, Si, P, S, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Cd , In, Sn, etc., and one or more of these may be used in combination.

Specific examples of the metal material include pure iron, silicon steel, iron-cobalt alloy, iron-nickel alloy, iron-chromium alloy, iron-aluminum alloy, carbonyl iron, stainless steel, or any of these. Composite materials and the like containing one or two or more types are included.

The average particle size of the magnetic powder 3 is not particularly limited as long as it exceeds 3 μm, but it is preferably 4 to 180 μm, more preferably 5 to 150 μm, even more preferably 7 to 100 μm. When the average particle size of the magnetic powder 3 is within the above range, the fluidity of the molding material 1 can be further enhanced.

If the average particle size of the magnetic powder 3 is less than the lower limit, the moldability of the molding material 1 may deteriorate depending on the specific gravity and particle shape of the constituent material. On the other hand, if the average particle diameter of the magnetic powder 3 exceeds the upper limit, the magnetic powder 3 may easily settle in the molding material 1 depending on the specific gravity and particle shape of the constituent material, resulting in a decrease in uniformity. There is

The average particle diameter of the first particles 31 is not particularly limited, but is preferably 10 to 200 μm, more preferably 12 to 150 μm, even more preferably 15 to 100 μm. When the average particle diameter of the first particles 31 is within the above range, magnetic properties such as magnetic permeability of the molding material 1 can be further enhanced.

The average particle size of the magnetic powder 3 and the first particles 31 means the volume average particle size, and can be measured using a laser diffraction particle size distribution analyzer.

Also, the constituent material of the first particles 31 may be a crystalline material, an amorphous material, or a material in which these materials are mixed in the particles.

Furthermore, in the magnetic powder 3, the first particles 31 made of a crystalline material and the first particles 31 made of an amorphous material may be mixed. As a result, two types of first particles 31 having different surface hardness are mixed. As a result, interaction between the first particles 31 during fluidization is optimized, and higher fluidity is ensured.

The sphericity of the first particles 31 is not particularly limited, but preferably 0.60 to 1.00, more preferably 0.70 to 1.00. When the sphericity of the first particles 31 is within the above range, the fluidity of the molding material 1 can be further enhanced.

In the scanning electron microscope (SEM) image of the first particles 31, the sphericity of the first particles 31 is defined as the equivalent circle diameter/circumscribed circle diameter, where a perfect circle equal to the area is a circle of equal area. can ask. Then, the equal area circle equivalent diameter/circumscribed circle diameter is calculated for 10 or more arbitrarily selected first particles 31, and the average value is defined as "the sphericity of the first particles 31".

The second particles 32 are particles exhibiting soft magnetism and having a composition different from that of the first particles 31 .

The constituent material of the second particles 32 may be appropriately selected from, for example, the materials described above as the constituent materials of the first particles 31, or other soft magnetic materials.

The difference in the composition of the constituent materials means a state in which the content of the constituent elements differs by 1% by mass or more.

By using the second particles 32 whose constituent material composition is different from that of the first particles 31 in this manner, two types of particles having different surface chemical states and surface hardness are mixed. As a result, the interaction between the first particles 31 and the second particles 32 during fluidization is optimized, ensuring higher fluidity.

Also, the average particle diameter of the second particles 32 is not particularly limited, but is preferably different from the average particle diameter of the first particles 31 . That is, the average particle size of the second particles 32 may be larger than the average particle size of the first particles 31, but is preferably smaller. As a result, even if the first particles 31 having a relatively large particle size are contained, the flowability of the molding material 1 can be suppressed from being lowered. In other words, the high fluidity of the molding material 1 can be ensured by the second particles 32 while ensuring excellent magnetic properties derived from the first particles 31 .

In addition, when the average particle diameter of the second particles 32 is smaller than the average particle diameter of the first particles 31, the difference between the average particle diameter of the first particles 31 and the average particle diameter of the second particles 32 is the flow rate of the molding material 1. Although it is appropriately set in consideration of the properties, as an example, it is preferably 1 to 100 μm, more preferably 3 to 80 μm, even more preferably 5 to 60 μm, particularly 8 to 50 μm. preferable. Thereby, the fluidity|liquidity of the molding material 1 can be improved more.

That is, if the difference in average particle size is less than the lower limit, the effect of increasing fluidity may decrease. In addition, since the difference in particle size between the first particles 31 and the second particles 32 is small, the effect of the second particles 32 being arranged so as to fill the gaps between the first particles 31 is weakened, and the filling property of the magnetic material is reduced. may decrease. On the other hand, if the difference in average particle size exceeds the above upper limit, the particle size of the second particles 32 may become too small, depending on the particle size of the first particles 31, and the flowability of the molding material 1 may decrease. .

The average particle size of the second particles 32 means the volume average particle size, and can be measured using a laser diffraction particle size distribution measuring device.

Also, the constituent material of the second particles 32 may be a crystalline material, an amorphous material, or a mixture of these materials.

Although the sphericity of the second particles 32 is not particularly limited, it is preferably 0.60 to 1.00, more preferably 0.70 to 1.00. When the sphericity of the second particles 32 is within the above range, the fluidity of the molding material 1 can be further enhanced.

In the scanning electron microscope (SEM) image of the second particles 32, the sphericity of the second particles 32 is defined as the equivalent circle diameter/circumscribed circle diameter, where a perfect circle equal to the area is a circle with an equal area. can ask. Then, for 10 or more arbitrarily selected second particles 32, the equal area circle equivalent diameter/circumscribed circle diameter is calculated, and the average value is defined as the "sphericity of the second particles 32".

Moreover, the second particles 32 may be added as necessary, and may be omitted.

Further, the magnetic powder 3 may contain soft magnetic particles other than the first particles 31 and the second particles 32, such as Ni-based soft magnetic particles and Co-based soft magnetic particles.

At least one of the first particles 31 and the second particles 32 may be surface-treated.

The surface treatment means an operation for modifying the particle surface. This operation includes, for example, treatment of the particle surface with a coupling agent and plasma treatment of the particles, as will be described later.

FIG. 2 is a cross-sectional view of one particle contained in the magnetic powder 3 shown in FIG. 1, and is a conceptual diagram showing an example of surface treatment.

The first particle 31 ′ shown in FIG. 2 is obtained by bonding a functional group represented by the following general formula (1) to the surface 31S of the first particle 31 . That is, the first particles 31' shown in FIG. 2 are obtained by subjecting the first particles 31 to a surface treatment, so that the surface 31S is covered with the functional group represented by the following general formula (1).

*-OX-R (1)
[In the formula, R represents an organic group, X is Si, Ti, Al, or Zr, and * is one of atoms constituting the first particle 31 . ]
Such functional groups are residues formed by surface treatment with various coupling agents such as silane coupling agents, titanium coupling agents, aluminum coupling agents, and zirconium coupling agents. In particular, it is preferably a residue of a coupling agent selected from the group consisting of silane-based coupling agents and titanium-based coupling agents. As a result, when the magnetic powder 3 is blended with the resin composition to form the molding material 1, the fluidity of the molding material 1 can be further enhanced.

As will be described in detail later, it is preferable that the first particles 31 satisfy a predetermined viscosity ratio (thixotropic ratio) when blended in the resin composition. From this point of view, by applying the surface treatment as described above, it is possible to control the viscosity ratio of the formulation and satisfy the predetermined conditions.

Further, when bonding the functional groups as described above, plasma treatment may be performed in advance as part of the surface treatment of the first particles 31 . For example, by applying oxygen plasma treatment, OH groups are generated on the surface 31S of the first particles 31, and as shown in FIG. becomes easier. Thereby, the functional groups can be bonded more strongly.

It is possible to confirm that the first particles 31 and the residues of the coupling agent in the first particles 31 ′ are bonded via oxygen atoms, for example, using a Fourier transform infrared spectrophotometer.

Moreover, the surface treatment as described above may be applied to the second particles 32 or both the first particles 31 and the second particles 32 .

From the viewpoint of enhancing the fluidity of the molding material 1, only the first particles 31 may be surface-treated. As a result, the surface states of the first particles 31 and the second particles 32 are different, so that they exhibit different behaviors when interacting with the resin 2, and as a result contribute to increasing the fluidity.

The first particles 31 preferably satisfy the following viscosity ratio (thixotropic ratio) at a temperature condition of 30° C. when mixed with a resin composition containing an epoxy resin and a phenol resin.

First, the first particles 31 are added to the resin composition, and the viscosity is measured with a viscoelasticity measuring device.

The viscosity when the shear shear rate is 1 is η1, and the viscosity when the shear shear rate of the viscoelasticity measuring device is 10 is η10.

At this time, it is preferable to satisfy η1/η10<3.4.

The epoxy resin used in this measurement is a polycondensate of allylated bisphenol A and epichlorohydrin.

Also, the phenolic resin used in this measurement is a 2-allylphenolformaldehyde polycondensate.

Further, when the first particles 31 are blended in the resin composition, the amount of the first particles 31 used is in the range of 15 to 50 parts by volume with respect to the total 100 parts by volume of the resin composition.

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

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

A solvent may be used in the resin composition, and examples of the solvent include butyl cellosolve acetate, 1-methoxy-2-propanol, and the like.

The viscosity ratio (thixotropic ratio) η1/η10 is less than 3.4 as described above, preferably 1.5 or more and less than 3.4, and 2.0 or more and 3.0 or less. more preferably 2.1 or more and less than 3.0, and particularly preferably 2.2 or more and 2.8 or less. When the viscosity ratio (thixotropic ratio) η1/η10 is within the above range, the fluidity of the molding material 1 can be further enhanced.

The viscosity was measured using a viscoelasticity measuring device ("RheoStress RS150" manufactured by HAAKE), and shear shear was applied to the resin composition containing the first particles 31 between the gaps of 50 to 1000 μm between parallel plates of 20 mmφ. can be measured while

Further, in order to satisfy the viscosity ratio in the above range, a method of performing surface treatment such as oxygen plasma treatment or coupling agent treatment, as described above, can be used. Among them, it is preferable to perform both the oxygen plasma treatment and the coupling agent treatment, in which case a coupling agent selected from the group consisting of a silane coupling agent and a titanium coupling agent is used as the coupling agent. is more preferred.

In addition, such surface treatment may be performed as needed, and may be omitted.

Further, another coat treatment may be applied to the base of the surface treatment described above. Examples of such coating treatment include resin coating such as silicone resin, silica coating, and the like. By applying such a coating treatment, the insulating properties of the particles of the magnetic powder 3 can be further enhanced.

In addition, such a coating process may be performed as needed, and may be omitted.

In addition, this coating treatment may be applied alone instead of as a base for the surface treatment described above.

The volume fraction of such magnetic powder 3 is preferably 50 to 90% by volume of the molding material 1, more preferably 55 to 85% by volume. As a result, the content of the magnetic powder 3 is sufficiently high, so that the molding material 1 having good magnetic properties can be obtained.

If the volume fraction of the magnetic powder 3 is less than the lower limit, the magnetic properties of the molding material 1 may deteriorate depending on the magnetic properties of the magnetic powder 3 . Further, when the volume fraction of the magnetic powder 3 exceeds the upper limit, the volume fraction of the resin 2 is relatively decreased, so that the fluidity of the molding material 1 is decreased and the mechanical properties after curing are deteriorated. There is a possibility that it may decrease.

On the other hand, an example of the mass fraction of the magnetic powder 3 is preferably 75 to 98% by mass, more preferably 80 to 97% by mass, of the molding material 1, although it varies depending on the specific gravity of each component. As with the volume fraction, this yields a molding material 1 with good magnetic properties.

(non-magnetic powder)
The non-magnetic powder 4 is a powder exhibiting non-magnetism, having an average particle size of 3 μm or less, and smaller than the magnetic powder 3 in average particle size.

Non-magnetic refers to having no ferromagnetism.

The molding material 1 containing such a non-magnetic powder 4 exhibits high fluidity during molding as described above, and the exudation of the resin 2 during molding is suppressed. As a result, the moldability of the molding material 1 is improved, and the fillability and uniformity of the magnetic powder 3 can be further improved, so that the molded body can have good magnetic properties. In addition, by suppressing the exudation of the resin 2, the occurrence of resin burrs and the like in the molded body is suppressed. In addition, it is possible to prevent the deterioration of the mechanical properties of the molded product due to the deterioration of the component balance of the molding material 1 due to exudation of the resin 2 . Therefore, a compact with little molding defects can be obtained.

The reason why the seepage of the resin 2 is suppressed is that the path of the seepage of the resin 2 is clogged with the non-magnetic powder 4 during molding.

Examples of constituent materials of the non-magnetic powder 4 include ceramic materials, glass materials, and the like, and materials containing at least one of these are used. Among these, those containing ceramic materials are preferably used. Since such non-magnetic powder 4 acts to reduce the melt viscosity of the molding material 1, the fluidity of the molding material 1 can be further enhanced.

Ceramic materials include, for example, oxide-based ceramic materials such as silica, alumina, zirconia, titania, magnesia, and calcia; nitride-based ceramic materials such as silicon nitride and aluminum nitride; and carbide-based materials such as silicon carbide and boron carbide. A ceramics material etc. are mentioned. Moreover, one of these may be used alone, or a mixture containing one of these may be used.

Also, the ceramic material preferably contains silica. Silica has a high affinity with the resin 2 and a high insulating property, so it is useful as a constituent material of the non-magnetic powder 4 used in the molding material 1 .

The true specific gravity of the constituent material of the nonmagnetic powder 4 is preferably 1.0 to 6.0 g/cm ³ , more preferably 1.2 to 5.0 g/cm ³ , more preferably 1.5 to 5.0 g/cm 3 . More preferably 4.5 g/cm ³ . Such a non-magnetic powder 4 has a small specific gravity, so that it easily flows together with the melt of the resin 2 . Therefore, when the melt of the resin 2 flows toward the gap of the mold during molding, the non-magnetic powder 4 easily flows together with the melt. As a result, the gap is filled with the non-magnetic powder 4, and the seepage of the resin 2 can be suppressed more reliably. The gap between the molds includes, for example, the gap (clearance) between the plunger and the cylinder of the transfer molding machine.

The average particle size of the nonmagnetic powder 4 is not particularly limited as long as it is 3 μm or less, but it is preferably 0.1 to 2.8 μm, more preferably 0.5 to 2.5 μm. Such a particle size is a particle size necessary for the non-magnetic powder 4 to fill the oozing path of the resin 2 and to easily flow together with the melt of the resin 2 .

That is, if the average particle size of the non-magnetic powder 4 is less than the lower limit, the particle size becomes too small. becomes difficult. On the other hand, if the average particle size of the non-magnetic powder 4 exceeds the upper limit, the particle size becomes too large. may become difficult to do.

The average particle size of the non-magnetic powder 4 means the volume average particle size, and can be measured using a laser diffraction particle size distribution analyzer.

The average particle diameter of the nonmagnetic powder 4 may be smaller than the average particle diameter of the first particles 31, but the difference is preferably 5 μm or more, more preferably 10 to 100 μm, more preferably 15 to 100 μm. More preferably it is 60 μm.

Although the sphericity of the non-magnetic powder 4 is not particularly limited, it is preferably 0.50 to 1.00, more preferably 0.75 to 1.00. When the sphericity of the non-magnetic powder 4 is within the above range, the flowability of the molding material 1 is ensured by utilizing the rolling of the non-magnetic powder 4 itself, while the non-magnetic powder 4 easily clogs gaps and the like. As a result, it becomes easier to suppress the exudation of the resin 2 . That is, it is possible to achieve both the fluidity of the molding material 1 and the suppression of the seepage of the resin 2 .

In addition, the sphericity of the non-magnetic powder 4 is determined by, in a scanning electron microscope (SEM) image of the non-magnetic powder 4, when a perfect circle equal to the area is defined as a circle of equal area, the equivalent diameter of a circle of equal area/circumscribed circle It can be obtained by diameter. Then, for 10 or more arbitrarily selected non-magnetic powders 4, the equal area circle equivalent diameter/circumscribed circle diameter is calculated, and the average value is taken as the "sphericity of the non-magnetic powder 4".

The volume fraction of such non-magnetic powder 4 is preferably 3 to 25% by volume, more preferably 5 to 20% by volume, of the magnetic powder 3 . Moreover, the mass fraction of the non-magnetic powder is preferably 0.5 to 10 mass %, more preferably 1 to 5 mass %, of the magnetic powder 3 . As a result, the content of the non-magnetic powder 4 is optimized, so that the molding material 1 that has sufficient fluidity and can more reliably suppress the bleeding of the resin 2 can be obtained.

If the volume fraction or mass fraction of the non-magnetic powder 4 is less than the lower limit, the fluidity improvement effect of the non-magnetic powder 4 is reduced, and the fluidity of the molding material 1 is reduced. , the effect of suppressing exudation of the resin 2 may also be reduced. Further, when the volume fraction or mass fraction of the nonmagnetic powder 4 exceeds the upper limit, the volume fraction or mass fraction of the magnetic powder 3 relatively decreases, or the volume fraction or mass fraction of the resin 2 decreases. Since the fraction is reduced, the magnetic properties and fluidity of the molding material 1 may be deteriorated.

On the other hand, although it varies depending on the specific gravity of each component, an example of the mass fraction of the nonmagnetic powder 4 is preferably 0.5 to 15% by mass, more preferably 0.7 to 10% by mass, of the molding material 1. is more preferred. Thereby, as in the case of the volume fraction, the molding material 1 having sufficient fluidity and capable of more reliably suppressing the seepage of the resin 2 can be obtained.

(fine magnetic powder)
The molding material 1 may, if necessary, contain fine magnetic powder that exhibits soft magnetism and has a particle size of 3 μm or less.

In the molding material 1 containing such fine magnetic powder, not only the non-magnetic powder 4 but also the fine magnetic powder contributes to high fluidity during molding and suppression of seepage of the resin 2. . As a result, the moldability of the molding material 1 is improved, and the fillability and uniformity of the magnetic powder 3 can be further improved.

Moreover, the volume fraction of the magnetic material in the molding material 1 can be further increased by containing the fine magnetic powder. That is, since the fine magnetic powder easily enters into the gaps, the packing property of the magnetic material is increased accordingly. As a result, the magnetic properties of the molding material 1 can be further enhanced.

The constituent material of the fine magnetic powder may be appropriately selected from, for example, the materials described above as the constituent material of the first particles 31, and other soft magnetic materials (for example, soft ferrite, Ni-based soft magnetic material, Co-based soft magnetic material, etc.). soft magnetic material, etc.).

Also, the composition of the constituent material of the fine magnetic powder may be the same as or different from the composition of the constituent material of the first particles 31 and the second particles 32 .

The difference in the composition of the constituent materials means a state in which the content of the constituent elements differs by 1% by mass or more.

The average particle size of the fine magnetic powder is not particularly limited as long as it is 3 μm or less, but it is preferably 0.1 to 2.8 μm, more preferably 0.5 to 2.5 μm. Such a particle size is a particle size necessary for the fine magnetic powder to fill the oozing path of the resin 2 and to easily flow together with the melt of the resin 2 .

The average particle size of the fine magnetic powder means the volume average particle size, and can be measured using a laser diffraction particle size distribution analyzer.

The average particle size of the fine magnetic powder should be 3 μm or less and smaller than the average particle size of the first particles 31, but the difference between them is preferably 5 μm or more, preferably 10 to 100 μm. More preferably, it is 15 to 60 μm.

Although the sphericity of the fine magnetic powder is not particularly limited, it is preferably 0.30 to 1.00, more preferably 0.50 to 1.00. When the sphericity of the fine magnetic powder is within the above range, the flowability of the molding material 1 is ensured by making use of the rolling of the fine magnetic powder itself, while the fine magnetic powder tends to clog gaps and the like, and the resin becomes more likely to become clogged. It becomes easy to suppress the exudation of 2. That is, it is possible to achieve both the fluidity of the molding material 1 and the suppression of seepage of the fine magnetic powder.

In addition, the sphericity of the fine magnetic powder is defined as the equivalent diameter of a circle of equal area/diameter of a circumscribed circle, where a perfect circle equal to the area of a scanning electron microscope (SEM) image of the fine magnetic powder is defined as a circle of equal area. can ask. Then, for 10 or more arbitrarily selected fine magnetic powders, the equal area circle equivalent diameter/circumscribed circle diameter is calculated, and the average value is taken as the "sphericity of the fine magnetic powder".

(other ingredients)
The molding material 1 may contain other components than the components mentioned above.

Other components include, for example, solvents, release agents, curing accelerators, adhesion aids, colorants, antioxidants, anti-corrosion agents, fillers, dyes, pigments, flame retardants and the like.

The molding material 1 as described above may be in the form of powder, granules, tablets formed by pressing into a desired shape, or the like.
<Method for manufacturing molding material>
Next, an example of a method for manufacturing the molding material 1 will be described. Here, an example of manufacturing the molding material 1 by subjecting the first particles 31 to surface treatment will be described.

The method of manufacturing the molding material 1 according to the present example comprises a step (i) of subjecting the first particles 31 to plasma treatment, and a reaction of the first particles 31 subjected to the plasma treatment in step (i) with a coupling agent. and a step (iii) of obtaining the molding material 1 by mixing the magnetic powder 3 containing the first particles 31 reacted with the coupling agent, the non-magnetic powder 4, the resin 2 and other additives. ) and

(Step (i))
First, the first particles 31 are subjected to plasma treatment. At this time, it is preferable that the surface 31S of the first particle 31 is uniformly plasma-treated. Thereby, the surface 31S of the first particle 31 can be activated and the coupling agent can be efficiently reacted.

For uniform plasma processing, for example, a method of performing plasma processing while dispersing the first particles 31 in the air can be used.

Also, the plasma treatment is preferably oxygen plasma treatment. Thereby, the surface 31S of the first particle 31 can be efficiently modified with OH groups.

The pressure of the oxygen plasma treatment is not particularly limited, but is preferably 100-200 Pa, more preferably 120-180 Pa.

The flow rate of the processing gas in the oxygen plasma treatment is not particularly limited, but is preferably 1000-5000 mL/min, more preferably 2000-4000 mL/min.

Although the output of the oxygen plasma treatment is not particularly limited, it is preferably 100 to 500W, more preferably 200 to 400W.

The treatment time of the oxygen plasma treatment is appropriately set according to the various conditions described above, but is preferably 5 to 60 minutes, more preferably 10 to 40 minutes.

Argon plasma treatment may be performed before oxygen plasma treatment. As a result, active sites for modifying the OH groups can be formed on the surface 31S of the first particle 31, so that the OH groups can be modified more efficiently.

Although the pressure of the argon plasma treatment is not particularly limited, it is preferably 10-100 Pa, more preferably 15-80 Pa.

The flow rate of the processing gas in the argon plasma treatment is not particularly limited, but is preferably 10-100 mL/min, more preferably 20-80 mL/min.

The output of the argon plasma treatment is preferably 100-500W, more preferably 200-400W.

The treatment time of the argon plasma treatment is preferably 5 to 60 minutes, more preferably 10 to 40 minutes.

(Step (ii))
Next, the first particles 31 immediately after being subjected to the plasma treatment in step (i) are reacted with the coupling agent. As this method, for example, the first particles 31 immediately after being subjected to the plasma treatment in step (i) are immersed in a diluted solution of the coupling agent, or the first particles 31 are directly sprayed with the coupling agent. method. As a result, the reaction proceeds more easily, and the surface 31S of the first particle 31 can be more easily modified. Note that "immediately after the plasma treatment" means a range of 0 to 24 hours after the plasma treatment.

Examples of coupling agents include silane-based coupling agents, titanium-based coupling agents, zirconia-based coupling agents, and aluminum-based coupling agents.

Among these, one or more selected from the group consisting of silane-based coupling agents and titanium-based coupling agents is particularly preferred. Thereby, the fluidity|liquidity of the molding material 1 can be improved more.

The amount of the coupling agent used is preferably 0.05 to 1 part by mass, more preferably 0.1 to 0.5 part by mass, with respect to 100 parts by mass of the first particles 31 .

Solvents for the reaction with the coupling agent include, for example, methanol, ethanol, isopropyl alcohol and the like.

The amount of the coupling agent used is preferably 0.1 to 2 parts by mass, more preferably 0.5 to 1.5 parts by mass, per 100 parts by mass of the solvent.

Further, the reaction time with the coupling agent (for example, immersion time in a diluted solution, etc.) is preferably 1 to 24 hours.

According to such a production method, it is possible to efficiently produce the magnetic powder 3 that can improve the fluidity when mixed with the resin composition.

(Step (iii))
Next, the magnetic powder 3 containing the first particles 31 reacted with the coupling agent, the non-magnetic powder 4, the resin 2, and other additives were mixed using a mixer, and then rolled to 120°C. , and kneaded for 5 minutes to obtain a kneaded product.

Next, the powdery molding material 1 is obtained by pulverizing the kneaded product after cooling.

After that, if necessary, the granular or powdered molding material 1 may be compressed into tablets.

Such a molding material 1 is molded by various molding methods such as transfer molding, injection molding, extrusion molding, and press molding. As a result, the resin 2 melts and flows to be molded into the desired shape.

After that, the resin 2 is cured to obtain a molded body. Such molded articles are used, for example, in reactors, inductors, and motor magnet fixing materials for automobiles.
<Molded body>
Next, an embodiment of the molded article of the present invention will be described.

The molded article according to this embodiment is a cured product of the molding material 1 (molding material according to the embodiment) described above. That is, the molding material 1 is molded while the molding material 1 is heated, so that the resin 2 hardens and the magnetic powder 3 and the non-magnetic powder 4 are bonded via the resin 2 . As a result, a compact having good magnetic properties and less molding defects can be obtained.

Such a compact preferably has a relative magnetic permeability of 10 or more, more preferably 15 or more, and even more preferably 18 or more. Since such a compact has good magnetic properties, it contributes to the realization of magnetic devices such as high-performance reactors, inductors, and motors. In addition, as the magnetic permeability of the compact is increased, it is possible to reduce the size of these magnetic devices.

The relative magnetic permeability of the compact is measured as follows.

First, the molding material 1 is molded by a low-pressure transfer molding machine to obtain a columnar molding with a diameter of 16 mm and a height of 32 mm.

Next, the magnetization curve (BH curve) of the obtained molding is obtained using an electromagnet type magnetizer and an AC/DC magnetization characteristics recorder (manufactured by Metron Giken Co., Ltd., MTR-1488). Then, the maximum value (maximum magnetic permeability) of the slope of the obtained initial magnetization curve is obtained, and the relative magnetic permeability is calculated by dividing the obtained maximum magnetic permeability by the magnetic permeability in vacuum.

Although the present invention has been described above based on the embodiments, the present invention is not limited to these.

For example, the molding material and molded article of the present invention may be obtained by adding arbitrary elements to the above embodiments.
Examples of reference forms are added below.
1.
a resin;
a magnetic powder containing first particles exhibiting soft magnetism and having an iron content of 85% by mass or more;
a non-magnetic powder exhibiting non-magnetism and having an average particle size of 3 μm or less and smaller than the magnetic powder;
A molding material characterized by having
2.
1. The constituent material of the non-magnetic powder includes a ceramic material. The molding material described in .
3.
2. The ceramic material contains silica. The molding material described in .
4.
1. The magnetic powder further includes second particles whose constituent material composition is different from that of the first particles. or 3. The molding material according to any one of.
5.
4. the first particles and the second particles have different average particle diameters; The molding material described in .
6.
5. The average particle diameter of the second particles is 1 to 100 μm smaller than the average particle diameter of the first particles; The molding material described in .
7.
1. The average particle size of the first particles is 10 to 200 μm. or 6. The molding material according to any one of.
8.
1. The magnetic powder has a volume fraction of 50 to 90% by volume. or 7. The molding material according to any one of.
9.
1. The volume fraction of the nonmagnetic powder is 3 to 25% by volume of the magnetic powder. or 8. The molding material according to any one of.
10.
1. or 9. A molded article, which is a cured product of the molding material according to any one of .
11.
10. Relative permeability is 10 or more. The molded article described in .

Next, specific examples of the present invention will be described.

1. Production of molding material (Example 1)
[1] Plasma treatment for the first particles First, using a rotary desktop vacuum plasma device (manufactured by Kai Semiconductor Co., Ltd., YHS-DΦS), pure iron powder (1000 g, manufactured by Kobe Steel, Ltd., MH20D, spherical 0.75) was pretreated with Ar plasma (gas type Ar, pressure 20 Pa, flow rate 50 mL/min, output 300 W, treatment time 40 minutes). Then, using the same apparatus, 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 performed.

[2] Coupling agent treatment for the first particles Next, the powder (20 g) after the O ₂ plasma treatment was treated with a silane coupling agent (0.3 g, Shin-Etsu Chemical Co., Ltd.) 5 minutes after the O ₂ plasma treatment. It was immersed in a solution of KBM303 (manufactured by Co., Ltd.) and ethanol (20 g) and stirred overnight with a shaker. Next, the solid content was separated by a centrifuge, washed with ethanol three times, and dried at 85° C. for 2 hours to obtain surface-treated pure iron powder (first particles).

[3] Mixing Treatment Next, pure iron powder subjected to the surface treatment described above and amorphous magnetic powder (KUAMET6B2, manufactured by Epson Atmix Corporation, sphericity 0.85) were prepared as the first particles.

As the second particles, alloy steel powder (DAPMSC5 manufactured by Daido Steel Co., Ltd., sphericity 0.80) was prepared. The volume fraction of the magnetic powder composed of the first particles and the second particles was calculated from the specific gravity and mass fraction of each component, and was 70.0% by volume of the entire molding material.

In addition, silica powder (sphericity 0.92) was prepared as a non-magnetic powder. Two types of silica powder having different average particle diameters were mixed and used. The volume fraction of the silica powder, calculated from the specific gravity and mass fraction of each component, was 11.7% by volume of the magnetic powder.

An epoxy resin (trisphenol type epoxy resin E1032H60 manufactured by Mitsubishi Chemical Corporation) was prepared as a thermosetting resin.

A novolak type phenolic resin (PR-HF-3 manufactured by Sumitomo Bakelite Co., Ltd.) was prepared as a curing agent.

In addition, other components (additives) include a release agent (Ester Wax WE-4, manufactured by Clariant Chemicals Co., Ltd.) and an imidazole-based curing accelerator (Curesol 2PZ-PW, manufactured by Shikoku Kasei Kogyo Co., Ltd.). prepared.

Next, these components were mixed to obtain a molding material. Table 2 shows the characteristics, compounding ratio, etc. of each component.

(Examples 2 to 9 and Comparative Examples 1 and 2)
A molding material was obtained in the same manner as in Example 1, except that each component and the blending ratio of the molding material were changed as shown in Table 2. The volume fraction of the magnetic powder was within the range of 55 to 85% by volume of the entire molding material. Also, the volume fraction of the silica powder was 5 to 20% by volume of the magnetic powder.

The alloy composition of the constituent materials of the magnetic powder described in Table 2 is as shown in Table 1.

Moreover, the symbols described in Table 2 have the following meanings.

NC3000: Nippon Kayaku Co., Ltd., biphenyl aralkyl type epoxy resin BAPP: Wakayama Seika Kogyo Co., Ltd., 2,2-bis [4-(4-aminophenoxy) phenyl] propane ABP-N: Mitsui Chemicals ( Co., Ltd., 1,3-bis-(3-aminophenoxy)benzene and 3-(3′-(3″-aminophenoxy)phenyl)amino-1-(3′-(3″-aminophenoxy) phenoxy)benzene mixtures2. 2. Evaluation of Molding Material 2.1 Evaluation of Fluidity The molding material obtained in each example and each comparative example was evaluated for the amount of spiral flow using a low-pressure transfer molding machine and a spiral flow mold.

Specifically, "KST-30" manufactured by Kotaki Seiki Co., Ltd. was prepared as a low-pressure transfer molding machine. Also, as a spiral flow mold, a spiral flow mold according to EMMI-1-66 was prepared. Then, the plunger of the low-pressure transfer molding machine was lowered to inject the molding material into the spiral flow mold. At this time, the mold temperature was 175° C., the injection pressure was 6.9 MPa, and the holding pressure time was 120 seconds. The amount of spiral flow was obtained based on the reaching length of the molding material injected as described above.

Table 2 shows the amount of spiral flow obtained.

2.2 Evaluation of Resin Exudation First, after the molding process using the low-pressure transfer molding machine performed in 2.1, the presence or absence of resin exuded to the top of the plunger was visually confirmed.

Next, the confirmation results were evaluated for resin exudation in light of the following evaluation criteria.

<Evaluation Criteria for Resin Exudation>
◯: No resin was found on the upper part of the plunger △: A small amount of resin was found on the upper part of the plunger ×: A large amount of resin was found on the upper part of the plunger Table 2 shows the above evaluation results.

2.3 Evaluation of magnetic properties The molding materials obtained in each example and each comparative example were injection molded using a low-pressure transfer molding machine at a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, and a curing time of 120 seconds. A cylindrical molding with a diameter of 16 mm and a height of 32 mm was obtained.

Then, the obtained molding was post-cured at 175° C. for 4 hours to prepare a test piece.

Next, the relative magnetic permeability μ based on the maximum magnetic permeability of the obtained test piece was measured using an electromagnet type magnetizer and an AC/DC magnetization characteristic recorder (MTR-1488, manufactured by Metron Giken Co., Ltd.). Table 2 shows the measurement results.

2.4 Evaluation of mechanical properties The molding materials obtained in each example and each comparative example were injection molded using a low-pressure transfer molding machine at a mold temperature of 175°C, an injection pressure of 9.8 MPa, and a curing time of 120 seconds. , a molded article having a width of 10 mm, a thickness of 4 mm and a length of 80 mm was obtained.

Then, the obtained molded article was post-cured at 175° C. for 4 hours to prepare a test piece.

Then, the bending strength of the obtained test piece was measured. Table 2 shows the measurement results.

2.5 Evaluation of glass transition temperature The molding materials obtained in each example and each comparative example were injection molded using a low-pressure transfer molding machine at a mold temperature of 175°C, an injection pressure of 9.8 MPa, and a curing time of 120 seconds. , 15 mm x 4 mm x 4 mm moldings were obtained.

Then, the obtained molded article was post-cured at 175° C. for 4 hours to prepare a test piece.

Then, the obtained test piece is measured using a thermomechanical analyzer (manufactured by Seiko Instruments Inc., TMA100) under the conditions of a measurement temperature range of 0 ° C. to 300 ° C. and a temperature increase rate of 5 ° C./min. Temperature was measured. Table 2 shows the measurement results.

As is clear from Table 2, it was confirmed that the molding material obtained in each example had high fluidity and could suppress resin exudation.

Therefore, the moldability of the molding material is improved, and the fillability and uniformity of the magnetic powder can be further improved, so that a molded product having good magnetic properties can be obtained, and the resin is prevented from bleeding out. It was proved that by suppressing the occurrence of resin burrs and the like in the molded article, it is possible to obtain a molded article with less molding defects.

1 molding material 2 resin 3 magnetic powder 4 non-magnetic powder 31 first particle 31' first particle 31S surface 32 second particle

Claims (7)

a thermosetting resin;
a curing agent;
(i) first particles exhibiting soft magnetism and having an iron content of 85% by mass or more and an average particle diameter of 10 to 200 μm ; a magnetic powder containing second particles, different from one particle, having an average particle size smaller than that of the first particles by 1 to 100 μm ;
a non-magnetic powder exhibiting non-magnetism and having an average particle size of 3 μm or less and an average particle size smaller than the magnetic powder;
A molding material characterized by having and being used for producing a molded article by a transfer molding method. 2. The molding material according to claim 1, wherein the constituent material of said non-magnetic powder includes a ceramic material. The molding material according to claim 2, wherein the ceramic material contains silica. The molding material according to any one of claims 1 to 3 , wherein the magnetic powder has a volume fraction of 50 to 90% by volume. 5. The molding material according to any one of claims 1 to 4 , wherein the non-magnetic powder has a volume fraction of 3 to 25% by volume of the magnetic powder. A molded article, which is a cured product of the molding material according to any one of claims 1 to 5 . 7. The compact according to claim 6 , which has a relative magnetic permeability of 10 or more.

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