JP2019102782A - Thermosetting resin composition, coil having magnetic core and/or outer package member, and method for manufacturing molded product - Google Patents

Abstract

To provide a thermosetting resin composition for forming a magnetic core and/or outer package member of a coil, which has a satisfactory magnetic property of iron loss or the like and a good fluidity in molding as one of objectives.SOLUTION: A thermosetting resin composition for forming a magnetic core and/or outer package member of a coil comprises: magnetic material particles; and a thermosetting resin. Supposing that in a volume-based particle diameter distribution curve of the magnetic material particles, a cumulative 10% value is D, and a cumulative 50% value is D, and a cumulative 90% value is D, the value of Dis 5-30 μm; and the value of D/Dis 25-50. It is preferred that the particle diameter distribution curve has a local maximum in each of a region of 1-3 μm in particle diameter and a region of 20-45 μm in particle diameter.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a thermosetting resin composition, a coil and a method of producing a molded article. In particular, the present invention relates to a thermosetting resin composition for forming a magnetic core of a coil (also expressed as a reactor or the like) and / or an exterior member.

  As parts of various electric and electronic products, coils (also called "reactor" or "inductor" or the like depending on the application field) having magnetic cores / exterior members are actively studied. In addition, moldable magnetic materials for producing a magnetic core and an exterior member of such a coil are also actively studied.

For example, 500 [mu] m in Patent Document 1, a soft magnetic powder, a magnetic material containing a resin enclosing in a dispersed state the soft magnetic powder, the soft magnetic powder has an average particle diameter D ₁ is 50μm or more following a coarse powder, the average and a fine powder of particle size less than D ₂ are 0.1μm or 30 [mu] m, the magnetic material content of the soft magnetic powder to the whole composite material is 80 vol% or more and 60 vol% It is disclosed. And, in the example, it is described that a molded article is obtained by mixing and melting these two types of fine particles with nylon which is a thermoplastic resin.

International Publication No. 2016/043025

As described above, moldable magnetic materials for obtaining a magnetic core and an exterior member, specifically, resin compositions containing magnetic particles have been actively studied.
Here, in the examples of the prior art described above, although a molded article is obtained using nylon which is a thermoplastic resin, when considering use under a severe environment, a molded article made of a thermosetting resin It is preferable to obtain

In the case of obtaining a molded article with a thermosetting resin, in general, the flowability of the thermosetting resin which is cured every moment becomes a problem.
In order to improve the magnetic properties of the magnetic core and the package member, it is necessary to improve the magnetic properties of the resin composition to be the element. Specifically, it is necessary to increase the filling amount of the magnetic particles in the resin composition (increasing the filling density). However, as the filling amount of the magnetic particles is increased (the filling density is increased), generally, the flowability at the time of molding is lowered.

One way to increase the flowability is to increase the particle size of the magnetic particles. This is understood in sense that sand with a larger particle size flows more easily than soil with a smaller particle size. However, when the particle size is increased, the gaps between the particles are increased, and the magnetic properties of the magnetic core are degraded. For example, it leads to the deterioration of iron loss.
That is, in the case of forming the magnetic core and / or the exterior member of the coil with a thermosetting resin composition, the magnetic properties deteriorate when the flowability is increased, and the flowability deteriorates when the magnetic properties are to be improved. there were.

  The present invention has been made in view of such circumstances. That is, the invention is to provide a thermosetting resin composition for forming a magnetic core and / or an exterior member of a coil, which has good magnetic properties such as iron loss and good flowability at the time of molding. As one of the purposes of

  As a result of studies, the present inventors have found that the above-mentioned problems can be achieved by the invention provided below.

According to the invention
A thermosetting resin composition for forming a magnetic core and / or an exterior member of a coil, comprising:
Containing magnetic particles and thermosetting resin,
Assuming that the cumulative 10% value in the volume-based particle size distribution curve of the magnetic particles is D ₁₀ , the cumulative 50% value is D ₅₀ , and the cumulative 90% value is D ₉₀ , the D ₅₀ value is 5 to 30 μm The thermosetting resin composition is provided, wherein the value of D ₉₀ / D ₁₀ is 25 to 50.

Moreover, according to the present invention,
There is provided a coil comprising a magnetic core and / or an exterior member composed of a cured product of the above thermosetting resin composition.

Moreover, according to the present invention,
There is provided a method for producing a molded article, wherein a melt of the above-mentioned thermosetting resin composition is injected into a mold using a transfer molding apparatus, and a molded article obtained by curing the melt is obtained.

  According to the present invention, there is provided a thermosetting resin composition for forming a magnetic core and / or an exterior member of a coil, which has good magnetic properties such as core loss and good flowability at the time of molding. Be done.

It is a figure for demonstrating the particle diameter distribution curve (volume basis) of a magnetic body particle typically. It is a figure showing typically a coil provided with a magnetic core. It is a figure which shows typically the coil (an aspect different from the thing of FIG. 2) provided with a magnetic core. It is a figure which shows an integrated inductor typically.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In all the drawings, similar components are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.
All drawings are for illustration only. The shapes, aspect ratios, etc. appearing in the drawings do not necessarily reflect reality, nor are they mathematically accurate.

In the present specification, the notation “a to b” in the description of the numerical range indicates a or more and b or less unless otherwise specified. For example, the expression "1 to 5% by mass" means "1 to 5% by mass".
In the notation of the group (atomic group) in the present specification, the notation not describing whether substituted or unsubstituted is intended to encompass both those having no substituent and those having a substituent. For example, the "alkyl group" includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).
The expression "(meth) acrylic" in the present specification represents a concept including both acrylic and methacrylic. The same applies to similar notations such as "(meth) acrylate".

In the present specification, "particle size" refers to the diameter of particles unless otherwise noted. The method of measuring the particle diameter will be described later.
In order to simplify the description, in the present specification, “a thermosetting resin composition for forming a magnetic core and / or an exterior member of a coil” is simply referred to as “a thermosetting resin composition” or a “resin composition It is also written as "thing".

<Thermosetting resin composition>
The thermosetting resin composition of the present embodiment is used to form a magnetic core and / or an exterior member of a coil, and includes magnetic particles and a thermosetting resin. Then, assuming that the cumulative 10% value in the volume-based particle diameter distribution curve of the magnetic particles is D ₁₀ , the cumulative 50% value is D ₅₀ , and the cumulative 90% value is D ₉₀ , the D ₅₀ value is 5 to 30 μm And the value of D ₉₀ / D ₁₀ is 25 to 50.

  With such a resin composition, the magnetic properties such as core loss can be improved, and the fluidity at the time of molding can also be improved. Can be explained.

As described in the conventional problems, according to the findings of the present inventors, when the particle size of the magnetic particles is too small, the flowability at the time of molding tends to deteriorate, while when the particle size is too large, the magnetism becomes magnetic. The characteristics tend to deteriorate.
Therefore, in the present invention, first, the value of D ₅₀ which is the “median” in the particle size distribution of the magnetic particles is set to 5 to 30 μm to balance the flowability at the time of molding and the magnetic characteristics. did.

However, this alone can not break away the "trade-off" between the fluidity and the magnetic properties at the time of molding.
Therefore, in the present invention, in addition to setting the value of D _{50 to 5} to 20 μm, “broadening” the particle size distribution of the magnetic particles (that is, the value of D ₉₀ / D ₁₀ is 25 to 50) Also to meet.

  The wide particle size distribution means that relatively large magnetic particles and relatively small magnetic particles are mixed in the resin composition. In this case, relatively small magnetic particles enter the gaps between relatively large magnetic particles, and the filling amount of magnetic particles per unit volume can be increased. Thereby, it is considered that the improvement of magnetic properties such as iron loss is achieved while maintaining the fluidity at the time of molding.

In addition, D ₁₀ , D ₅₀ , D _{90 and the} like are indicators often used in the particle size distribution of particles. Although these definitions in the present specification are not different from the general definitions, they will be described just in case.
FIG. 1 is a graph schematically showing a volume-based particle size distribution curve of certain magnetic particles. The horizontal axis of the graph is the particle diameter, and the vertical axis is the relative particle amount (volume basis).
Assuming that the area of the entire region surrounded by this curve and the horizontal axis of the graph is 100, the particle diameter is 10 when the area is 10 and the particle diameter is 50 when the area is ₁₀ when integrated from the small particle diameter side. The particle diameter of D ₅₀ and the area of which is 90 is D ₉₀ .

The value of D ₅₀ is not particularly limited as long as it is 5 to 30 μm, and preferably 10 to 20 μm.
The value of D ₉₀ / D ₁₀ is not particularly limited as long as it is 25 to 50, but is preferably 32 to 48, and more preferably 35 to 45.
The value of D ₁₀ itself is preferably 0.5 to 5 μm, more preferably 1 to 3 μm.
The value of D ₉₀ itself is preferably 16 to 240 μm, more preferably 35 to 135 μm, and still more preferably 45 to 135 μm.
By appropriately adjusting these values, the magnetic properties and the fluidity can be further optimized.

  The particle size distribution curve preferably has maxima at least in the region of 1 to 3 μm particle diameter and in the region of 20 to 45 μm particle diameter. For example, as shown in FIG. 1, the particle size distribution curve has two maxima (the particle size distribution is bimodal), and the smaller one of the particle sizes exists between 1 and 3 μm of particle size. The embodiment in which the larger maximum particle diameter is present in the region of 20 to 45 μm particle diameter is preferred.

  By preparing the resin composition with magnetic particles of such a particle size distribution, relatively small magnetic particles enter the gap between relatively large magnetic particles as described above, and magnetic particles per unit volume can be obtained. As a result, it is expected to further improve the fluidity and magnetic properties at the time of molding.

Also, as described above, when the particle size distribution curve has local maxima in at least the region of 1 to 3 μm particle diameter and the region of 20 to 45 μm particle diameter, the portion of particle diameter 1 to 3 μm in the particle diameter distribution curve _{S 1} and the area (integral value) of, when the area of the portion of the particle diameter 20~45μm (integrated value) was _{S 2,} it is preferable that the value of S 1 / _{S 2} is 0.1 to 2.0 And 0.2 to 1.0 are more preferable.

By such a value of S ₁ / S ₂ , the above-mentioned “a relatively small magnetic particle enters a gap between relatively large magnetic particles” is more highly realized (in flat terms, The gaps between the particles are reduced) and further improvement of the magnetic properties can be expected.

  The particle size distribution curve may have only one maximum, or may have a maximum (for example, a third maximum) other than the above two maximums. However, from the viewpoint of further improvement of the flowability and magnetic properties at the time of molding, as described above, one maximum is provided for each of the region with a particle diameter of 1 to 3 μm and the region with a particle diameter of 20 to 45 μm. It is preferable to have. Moreover, it is preferable not to have a maximum in the area | region other than that.

The method of determining the particle size distribution curve will be described.
The particle size distribution curve can be obtained, for example, by a laser diffraction / scattering type particle size distribution measuring apparatus. For example, a particle size distribution curve can be obtained by measuring the magnetic particles dry using a particle size distribution measuring apparatus “LA-950” manufactured by HORIBA. In addition, it is generally recognized that the particle diameter obtained by this measurement is a primary particle diameter.

Examples of a method of obtaining magnetic particles having a desired particle diameter distribution curve include a method of mixing magnetic particles having a plurality of known particle diameter distributions and the like.
The chemical composition and the like of the magnetic particles will be described later.

  Hereinafter, each component of the thermosetting resin composition of this embodiment is explained in full detail.

(Magnetic particles)
Any magnetic particle can be used as long as the magnetic particles as a whole satisfy the above distribution and the like. Specifically, magnetic particles containing one or more elements selected from the group consisting of iron, chromium, cobalt, nickel, silver and manganese can be mentioned. By selecting such magnetic particles, the magnetic properties can be further enhanced.

  The magnetic particles may be a crystalline material, an amorphous material, or a mixture of these. Moreover, as a magnetic body particle, you may use what consists of 1 type of chemical composition, and you may use together 2 or more types of thing of a different chemical composition.

In particular, as the magnetic particles, those containing iron-based particles are preferable. The iron-based particles refer to particles mainly composed of iron atoms (the content of iron atoms is the largest in the chemical composition), and more specifically, the content of iron atoms is one in the chemical composition. It refers to the number of ferrous alloys.
More specifically, particles (soft magnetic iron-rich particles) exhibiting soft magnetism and having an iron atom content of 85% by mass or more can be used as the iron-based particles. Note that soft magnetism refers to ferromagnetism having a small coercive force, and in general, ferromagnetism having a coercive force of 800 A / m or less is referred to as soft magnetism.

  As a constituent material of such particle | grains, the metal containing material whose content rate of iron as a constitutent element is 85 mass% or more is mentioned. As described above, a metal material having a high content of iron as a constituent element exhibits soft magnetism in which magnetic properties such as permeability and magnetic flux density are relatively good. For this reason, when it shape | molds, for example to the magnetic core of a coil, an exterior member, etc., the resin composition which can show a favorable magnetic characteristic is obtained.

  Examples of the form of the above-mentioned metal-containing material include, in addition to simple substances, solid solutions, eutectics, alloys such as intermetallic compounds, and the like. By using particles made of such a metal material, it is possible to obtain a resin composition having excellent magnetic properties derived from iron, that is, magnetic properties such as high magnetic permeability and high magnetic flux density.

  Moreover, said metal containing material may contain elements other than iron as a constitutent element. As elements other than iron, 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 above metal-containing materials include, for example, pure iron, silicon steel, iron-cobalt alloy, iron-nickel alloy, iron-chromium alloy, iron-aluminum alloy, carbonyl iron, stainless steel, or the like The composite material etc. which contain 1 type or 2 types or more are mentioned. Carbonyl iron can be preferably used from the viewpoint of availability and the like.

  In the above description, the iron-based particles are mainly described, but of course, the magnetic particles may be other particles. For example, the magnetic particles may be Ni-based soft magnetic particles, Co-based soft magnetic particles, or the like.

Also, the magnetic particles may be subjected to surface treatment. For example, the surface may be treated with a coupling agent or plasma treated. By such surface treatment, it is possible to attach a functional group to the surface of the magnetic particles. The functional groups can cover part or all of the surface of these particles.
As such a functional group, a functional group represented by the following general formula (1) can be used.
* -O-X-R (1)
[Wherein, R represents an organic group, X is Si, Ti, Al, or Zr, and * is one of the atoms constituting the magnetic particles. ]

  The functional group is, for example, a residue formed by surface treatment with a known coupling agent such as a silane coupling agent, a titanium coupling agent, an aluminum coupling agent, or a zirconium coupling agent. It is preferable that it is a residue of a coupling agent selected from the group consisting of a silane coupling agent and a titanium coupling agent. Thereby, when the magnetic particles are mixed with the resin composition to form a resin composition, the fluidity can be further enhanced.

In the case of surface treatment with a coupling agent, a method of immersing the magnetic particles in a diluted solution of the coupling agent or directly spraying the coupling agent onto the magnetic particles may be mentioned.
The amount of coupling agent used is, for example, preferably 0.05 to 1 parts by mass, and more preferably 0.1 to 0.5 parts by mass, with respect to 100 parts by mass of the magnetic particles.
As a solvent when making a coupling agent and magnetic body particle | grains react, methanol, ethanol, isopropyl alcohol etc. are mentioned, for example. Moreover, it is preferable that it is 0.1-2 mass parts with respect to 100 mass parts of solvents, and, as for the usage-amount of the coupling agent at this time, it is more preferable that it is 0.5-1.5 mass parts.
The reaction time of the coupling agent and the magnetic particles (for example, the immersion time in a dilute solution) is preferably 1 to 24 hours.

  In addition, when bonding a functional group as described above, plasma treatment may be performed in advance as part of the surface treatment of the magnetic particles. For example, when oxygen plasma treatment is performed, OH groups are generated on the surface of the magnetic particles, and bonding between the magnetic particles and the residue of the coupling agent through oxygen atoms is facilitated. This enables functional groups to be bound more firmly.

The plasma treatment here is preferably oxygen plasma treatment. Thereby, the OH group can be efficiently modified on the surface of the magnetic particles.
The pressure of the oxygen plasma treatment is not particularly limited, but is preferably 100 to 200 Pa, and more preferably 120 to 180 Pa.
The flow rate of the processing gas in the oxygen plasma treatment is not particularly limited, but is preferably 1000 to 5000 mL / min, and more preferably 2000 to 4000 mL / min.
The output of the oxygen plasma treatment is not particularly limited, but is preferably 100 to 500 W, and more preferably 200 to 400 W.
Although the processing time of oxygen plasma processing is suitably set according to the above-mentioned various conditions, it is preferable that it is 5 to 60 minutes, and it is more preferable that it is 10 to 40 minutes.

  Further, argon plasma treatment may be further performed before the oxygen plasma treatment. Thereby, since the active point for modifying the OH group can be formed on the surface of the magnetic particles, the modification of the OH group can be performed more efficiently.

The pressure of the argon plasma treatment is not particularly limited, but is preferably 10 to 100 Pa, and more preferably 15 to 80 Pa.
The flow rate of the processing gas in argon plasma treatment is not particularly limited, but is preferably 10 to 100 mL / min, and more preferably 20 to 80 mL / min.
The output of argon plasma treatment is preferably 100 to 500 W, and more preferably 200 to 400 W.
The treatment time of argon plasma treatment is preferably 5 to 60 minutes, and more preferably 10 to 40 minutes.

The fact that the magnetic particles and the residue of the coupling agent are bonded via an oxygen atom can be confirmed by, for example, a Fourier transform infrared spectrophotometer.
In addition, the surface treatment as described above may be applied to all the particles contained in the resin composition, or may be applied to only some of the particles.

  Further, another coat treatment may be applied to the base of the surface treatment described above. As this coating process, a silica coat etc. other than resin coat like silicone resin etc. are mentioned, for example. By performing such a coating process, the insulation of the magnetic particles can be further enhanced. Such coating treatment may be performed as needed, and may be omitted. This coating treatment may be applied alone, not as a base of the above-described surface treatment.

As another point of view, it is preferable that the magnetic particles have a shape close to a true circle (a true sphere). It is thought that this makes it possible to reduce the friction between the particles and to further improve the flowability.
Specifically, the “roundness” defined below is obtained for any 10 or more (preferably 50 or more) of magnetic particles, and the average roundness obtained by averaging the values is It is preferably 0.60 or more, and more preferably 0.75 or more.
Definition of roundness: When the contour of magnetic particles is observed with a scanning electron microscope, the equivalent circular equivalent diameter obtained from the contour is Req, and the radius of the circle circumscribing the contour is Rc, Value of Req / Rc.

The content of the magnetic particles is preferably 95% by mass or more, more preferably 95 to 99.5% by mass, still more preferably 95 to 98.5% by mass with respect to the total solid content (nonvolatile component) of the resin composition. %. By setting the amount of magnetic particles to this amount, the magnetic properties can be further improved.
As another aspect, the content of the magnetic particles is preferably 60% by volume or more, more preferably 70 to 95% by volume, and still more preferably 70 to 95% by volume with respect to the total solid content (nonvolatile component) of the resin composition. It is 90% by volume. By setting the amount of magnetic particles to this amount, the magnetic properties can be further improved. In particular, it is preferable to increase this volume% in terms of the “filling factor” of the magnetic particles.

(Thermosetting resin)
As the thermosetting resin, for example, epoxy resin, phenol resin, polyimide resin, bismaleimide resin, urea (urea) resin, melamine resin, polyurethane resin, cyanate ester resin, silicone resin, oxetane resin (oxetane compound), (Meta Acrylate resin, unsaturated polyester resin, diallyl phthalate resin, benzoxazine resin and the like. These may be used alone or in combination of two or more.

  Thermosetting resins include novolac type phenolic resins such as phenol novolac resin, cresol novolac resin, bisphenol A type novolac resin, and triazine skeleton-containing phenolic novolac resin; unmodified resole phenolic resin, soy sauce, linseed oil, walnut oil, etc. Phenolic resins such as resole type phenolic resin such as modified oil modified resole phenolic resin, phenolic aralkyl resin, aralkyl type phenolic resin such as biphenyl aralkyl type phenolic resin; bisphenol A type epoxy resin, bisphenol F type epoxy resin, tetramethyl 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 Bisphenol type epoxy resin such as Z-type epoxy resin; novolac type epoxy resin such as phenol novolac type epoxy resin, cresol novolac type epoxy resin; biphenyl type epoxy resin, biphenyl aralkyl type epoxy resin, aryl alkylene type epoxy resin, naphthalene type epoxy Resin, anthracene type epoxy resin, phenoxy type epoxy resin, dicyclopentadiene type epoxy resin, norbornene type epoxy resin, adamantane type epoxy resin, fluorene type epoxy resin, epoxy resin such as trisphenylmethane type epoxy resin, urea (urea) resin Resin having a triazine ring such as melamine resin; unsaturated polyester resin; maleimide resin such as bismaleimide compound; polyurethane resin; diallyl phthalate resin Silicone resin; benzoxazine resin; polyimide resin; polyamide imide resin; benzocyclobutene resin, novolac type cyanate resin, bisphenol A type cyanate resin, bisphenol E type cyanate resin, cyanate resin such as tetramethyl bisphenol F type cyanate resin, etc. Cyanate ester resin etc. are mentioned.

The thermosetting resin may be used alone or in combination of two or more. Also, resins of the same type or those of different weight average molecular weights may be used in combination. Furthermore, a certain resin and its prepolymer may be used in combination.
The thermosetting resin may be semi-cured (solid) at room temperature of 25 ° C.

From the viewpoint of heat resistance, the thermosetting resin preferably contains, for example, an epoxy resin. The epoxy resin can include a multifunctional epoxy resin having two or more epoxy groups in the molecule. Examples of the epoxy resin include one or more solid epoxy resins selected from the group consisting of trisphenylmethane epoxy resin, dicyclopentadiene epoxy resin, bisphenol A epoxy resin, and tetramethyl bisphenol F epoxy resin. Can be used.
When the thermosetting resin contains an epoxy resin, the heat resistance of the resulting molded article can be increased.

  In particular, as the epoxy resin, an epoxy resin including a structure represented by the following general formula (I) is preferable from the viewpoint of improvement in moldability by lowering the viscosity.

In general formula (I), two R's each independently represent a hydrogen atom or an alkyl group.
The alkyl group of R preferably has 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms, and still more preferably 1 carbon atom (i.e., a methyl group). The two R's are preferably a methyl group or a hydrogen atom.

  The content of the thermosetting resin is, for example, 0.5 to 20% by mass, preferably 1 to 15% by mass, based on 100% by mass of the entire nonvolatile components of the resin composition. The content of the thermosetting resin is, for example, 5 to 30% by volume, preferably 10 to 30% by volume, based on 100% by volume of the total nonvolatile components of the resin composition. By setting it as such a numerical range, moldability and mechanical properties can be improved.

(Hardening agent)
The resin composition of the present embodiment may contain a curing agent of the above-mentioned thermosetting resin. Thereby, the resin composition can be sufficiently cured, and improvement of the heat resistance and durability of the resulting molded article can be expected.
The curing agent may be semi-cured (solid) at room temperature of 25 ° C.

When the thermosetting resin contains a phenol resin such as novolak type phenol resin, hexamethylenetetramine can be used as the curing agent.
When the thermosetting resin contains an epoxy resin, as a curing agent, for example, aliphatic polyamines, aromatic polyamines, amine compounds such as disiamine diamide, alicyclic acid anhydrides, aromatic acid anhydrides, etc. An acid anhydride, a polyphenol compound (phenolic curing agent) such as a novolak type phenol resin, an imidazole compound, or the like can be used.
When the thermosetting resin contains a maleimide resin, for example, an imidazole compound can be used as the curing agent.

In particular, the curing agent preferably comprises a phenolic curing agent. More specifically, a phenol-based curing agent containing 2 to 5 phenolic hydroxyl groups in one molecule is preferable, and a phenol-based curing agent containing 3 to 4 phenolic hydroxyl groups in one molecule is more preferable.
By using a phenol-based curing agent, the curability can be further enhanced, and further improvement of the durability of the molded product can be expected. This effect is particularly remarkable when the thermosetting resin contains an epoxy resin.

When a curing agent is used, one type may be used alone, or two or more types may be used in combination.
When the curing agent is used, the content thereof is, for example, 0.5 to 20% by mass, preferably 1 to 15% by mass, based on 100% by mass of the total solid content of the resin composition. The content of the curing agent is, for example, 5 to 30% by volume, preferably 10 to 30% by volume, based on 100% by volume of the entire nonvolatile components of the resin composition. By setting it as such a numerical range, moldability and mechanical properties can be improved.

  Moreover, when using a hardening | curing agent, it is preferable to adjust amount ratio with the above-mentioned thermosetting resin appropriately. Specifically, it is preferable to adjust the quantitative ratio so that the value of the so-called "equivalent" becomes around 1. More specifically, the ratio of the number of moles of reactive functional group (such as phenolic hydroxyl group) that the curing agent contains to the number of moles of reactive functional group (such as epoxy group) that the thermosetting resin contains is 0. It is preferable that it becomes .8-1.2.

(Hardening accelerator)
The resin composition of the present embodiment may contain a curing accelerator. Thereby, the curability of a resin composition can be improved.

  Any curing accelerator can be used as long as it accelerates the crosslinking reaction of the thermosetting resin. For example, phosphorus atom-containing compounds such as organic phosphines, tetra-substituted phosphonium compounds, phosphobetaine compounds, adducts of phosphine compounds with quinone compounds, adducts of phosphonium compounds with silane compounds, etc .; imidazoles such as 2-methylimidazole (imidazole Curing accelerators); Amidines and tertiary amines exemplified by 1,8-diazabicyclo [5.4.0] undecene-7, benzyldimethylamine and the like; nitrogen atom-containing compounds such as tertiary amines and quaternary salts of amidines and amines; Can be mentioned.

When using a hardening accelerator, only 1 type may be used and 2 or more types may be used.
When a curing accelerator is used, its content is preferably 0.01 to 1% by mass, and more preferably 0.05 to 1% by mass, based on 100% by mass of the total solid content (nonvolatile component) of the resin composition. It is 0.8 mass%. By setting it as such a numerical range, the effect of a hardenability improvement is fully acquired.

(Release agent)
The resin composition of the present embodiment may contain a release agent. Thereby, the releasability of the resin composition at the time of shaping | molding can be improved.

  Examples of the mold release agent include natural waxes such as carnauba wax, synthetic waxes such as montanic acid ester wax and oxidized polyethylene wax, higher fatty acids such as zinc stearate and metal salts thereof, and paraffin. These may be used alone or in combination of two or more.

  When a release agent is used, its content is preferably 0.01 to 3% by mass, and more preferably 0.05 to 3% by mass, based on 100% by mass of the total solid content (nonvolatile component) of the resin composition. It is 2 mass%. Thereby, the effect of mold release property improvement can be acquired reliably.

(Non-magnetic particles)
The resin composition of the present embodiment may include nonmagnetic particles exhibiting nonmagnetism from the viewpoint of controlling flowability and the like. As the nonmagnetic particles, for example, particles having a cumulative 50% value of 3 μm or less in a particle size distribution curve can be used. In the present specification, nonmagnetic refers to having no ferromagnetism.

  The resin composition containing such nonmagnetic particles exhibits higher fluidity at the time of molding, and the exudation of the thermosetting resin at the time of molding is further suppressed. For this reason, the moldability of the resin composition becomes better, and the filling property and the uniformity of the magnetic particles can be further enhanced. Thus, particularly good magnetic properties are obtained in the molded body.

  In addition, since the exudation of the thermosetting resin is suppressed, the generation of resin burrs and the like at the time of molding is suppressed. In addition, with the exudation of the thermosetting resin, it is possible to prevent the component balance of the resin composition from being broken and the mechanical properties of the molded body being lowered. Therefore, a molded article with few molding defects can be obtained.

  Examples of the constituent material of the nonmagnetic particles include ceramic materials and glass materials. Among these, those containing a ceramic material are preferably used. Such nonmagnetic particles have high affinity to the thermosetting resin, and can maintain the flowability of the resin composition.

Examples of the ceramic material include 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 carbides such as silicon carbide and boron carbide. Examples include ceramic materials and the like.
In addition, the ceramic material particularly preferably contains silica. Silica is useful as a constituent particle of nonmagnetic particles because it has high affinity to a thermosetting resin and high insulation.

  The true specific gravity of the constituent material of the nonmagnetic particles is preferably 1.0 to 6.0, more preferably 1.2 to 5.0, and 1.5 to 4.5 More preferable. Such nonmagnetic particles tend to flow together with the melt of the thermosetting resin because of their low specific gravity. For this reason, when the melt of the thermosetting resin flows toward the gap of the mold or the like at the time of molding, the nonmagnetic particles easily flow together with the melt. As a result, the gap is closed by the nonmagnetic particles, and the bleeding of the thermosetting resin can be more reliably suppressed. In addition, with the clearance gap of a shaping | molding die, the clearance gap (clearance) of the plunger of a transfer molding machine, and a cylinder, etc. are mentioned, for example.

  The cumulative 50% value in the volume-based particle size distribution curve of the nonmagnetic particles is not particularly limited, but is typically 3 μm or less, preferably 0.1 to 2.8 μm, and more preferably 0. 0.5 to 2.5 μm. Such a particle size is a particle size necessary for the nonmagnetic particles to fill the exudation path of the thermosetting resin, and is a particle size which easily flows together with the melt of the thermosetting resin.

The cumulative 50% value in the volume-based particle size distribution curve of nonmagnetic particles is preferably 3 μm or less and smaller than D _{50 of} magnetic particles, but the difference is preferably 5 μm or more. 10 to 100 μm is more preferable, and 15 to 60 μm is particularly preferable.

  Also, the average roundness of the nonmagnetic particles contained in the nonmagnetic particles (this definition is the same as in the magnetic particles) is not particularly limited, but is preferably 0.50 to 1, 0 More preferably, it is .75-1. When the roundness is in this range, the fluidity of the resin composition can be secured by making use of the rolling of the nonmagnetic particles themselves, while the nonmagnetic particles are easily clogged in gaps or the like, and the thermosetting resin It becomes easy to control the exudation. That is, the flowability of the resin composition and the suppression of the exudation of the thermosetting resin can be compatible.

  When nonmagnetic particles are used, the amount is preferably 1 to 10% by mass, and more preferably 2 to 5% by mass, based on 100% by mass of the total solid content (nonvolatile component) of the resin composition. As a result, a resin composition can be obtained which has even higher fluidity and can more surely suppress the exudation of the thermosetting resin.

(Thermoplastic resin)
The resin composition of the present embodiment is thermosetting, but may contain a thermoplastic resin from the viewpoint of control of flowability and moldability.

  Examples of the thermoplastic resin include acrylic resins, polyamide resins (eg, nylon etc.), thermoplastic urethane resins, polyolefin resins (eg polyethylene, polypropylene etc.), polycarbonate, polyester resins (eg polyethylene terephthalate, polybutylene) Terephthalate etc.), polyacetal, polyphenylene sulfide, polyetheretherketone, liquid crystal polymer, fluorocarbon resin (eg polytetrafluoroethylene, polyvinylidene fluoride etc.), modified polyphenylene ether, polysulfone, polyether sulfone, polyarylate, polyamide imide, poly Ether imide, thermoplastic polyimide, etc. are mentioned.

When a thermoplastic resin is used, one type may be used alone, or two or more different types may be used in combination. Moreover, even if it is resin of the same type, you may use together 2 or more types of a different weight average molecular weight. Furthermore, a certain resin and its prepolymer may be used in combination.
When the thermoplastic resin is used, the amount is preferably 1 to 10% by mass, and more preferably 2 to 5% by mass, based on 100% by mass of the total solid content (nonvolatile component) of the resin composition. This is considered to be sufficient to obtain the effect of adjusting the flowability and the formability.

(Other ingredients)
The resin composition of the present embodiment may contain components other than the components described above.
For example, it may contain a low stress agent, a coupling agent, an adhesion assistant, a colorant, an antioxidant, a corrosion inhibitor, a dye, a pigment, a flame retardant and the like.

  Examples of the low stress agent include polybutadiene compounds, acrylonitrile butadiene copolymer compounds, silicone oils such as silicone oil and silicone rubber. When using a low stress agent, only 1 type may be used and 2 or more types may be used together.

  As the coupling agent, the above-mentioned coupling agent used for the surface treatment of the magnetic particles can be used. For example, a silane coupling agent, a titanium coupling agent, a zirconia coupling agent, an aluminum type Coupling agents etc. may be mentioned. When using a coupling agent, only 1 type may be used and 2 or more types may be used together.

  When a resin composition contains other components, the quantity is suitably adjusted, for example in the range of 0.001-10 mass%, when the solid content (nonvolatile component) whole of a resin composition is made into 100 mass%.

(Physical properties and properties of resin composition, etc.)
As described above, the resin composition of the present embodiment has good flowability at the time of molding by using magnetic particles having a specific particle size distribution. To describe quantitatively, the flow length measured by a spiral flow test at a temperature of 175 ° C. is preferably 50 cm or more. The flow length is more preferably 60 cm or more, still more preferably 70 cm or more. It is preferable that the resin composition has such a flow length in view of mass producibility of the magnetic core and / or the exterior member.
The upper limit of the flow length is, for example, 260 cm.

  Here, the above-mentioned spiral flow test is carried out, for example, using a low-pressure transfer molding machine ("KTS-15" manufactured by Kotaki Seiki Co., Ltd.) to mold a mold for spiral flow measurement according to EMMI-1-66. It can be carried out by injecting the sealing resin composition under the conditions of a temperature of 175 ° C., an injection pressure of 6.9 MPa, and a curing time of 120 seconds, and measuring the flow length.

  The flowability and the formability can also be evaluated by so-called melt viscosity. Specifically, the melt viscosity at 175 ° C. of the resin composition of the present embodiment is, for example, 1 to 500 Pa · s, preferably 1 to 200 Pa · s, and more preferably 1 to 100 Pa · s. More preferably, it is 1 to 50 Pa · s, and particularly preferably 1 to 20 Pa · s.

By making melt viscosity below the said upper limit, fluidity | liquidity can be improved and the outstanding moldability can be implement | achieved. Further, by setting the melt viscosity to the above lower limit value or the like, it is possible to suppress the occurrence of resin leakage from the mold at the time of molding, and it is possible to suppress the sedimentation of magnetic particles in the resin composition at the time of molding. In addition, damage to the insulating layer on the surface of the magnetic particles or nonmagnetic particles can be suppressed.
For the method of measuring the melt viscosity, refer to the examples described below.

  Furthermore, the resin composition of the present embodiment can be expected to have a merit that the heat shrinkage rate of the molded article obtained by melting and molding the resin composition is small. This is because, as described above, when the magnetic particles have a suitable particle size distribution, the "gaps" of the magnetic particles in the molded article are reduced and the magnetic particles are densely packed, resulting in heat. It is estimated that the contraction rate decreases. The characteristic that the thermal contraction rate is small is preferable in terms of dimensional controllability and the like when forming the magnetic core and / or the exterior member of the coil (reactor).

When the heat shrinkage rate is quantitatively described, when a cured molded product produced by cooling the thermosetting resin composition after heating and melting is tested for 4 hours at 175 ° C., the cured molding before the test is carried out. Assuming that the length in the longitudinal direction of the body is L ₀ and the heat shrinkage of the cured molded product after the test is L ₁ , the dimensional shrinkage represented by (L ₁ / L ₀ ) × 100 is 1% or less Is preferred.
For details of the conditions of this measurement method, refer to the examples described below.

  The resin composition of the present embodiment may be solid at room temperature of 25 ° C., and may be in the form of powder, granules, tablets or the like.

(Method for producing resin composition)
An example of the manufacturing method of the resin composition of this embodiment is demonstrated.

First, the above components (magnetic powder, thermosetting resin, etc.) are mixed using a mixer, and then kneaded using a roll, for example, at 120 ° C. for 5 to 10 minutes. obtain. In addition, about the magnetic body powder, the above-mentioned surface treatment is previously performed as needed.
Thereafter, the obtained kneaded product is cooled and pulverized to obtain a powdered resin composition (molding material).
After this, if necessary, the powdery resin composition may be compressed into a granular or tablet form by tableting or the like.
By the above, the resin composition suitable for transfer molding is obtained. In addition, by solidifying the resin composition at room temperature of 25 ° C., the transportability and storage stability can be enhanced.

<Production method of molded article>
Molded articles, such as a magnetic core of a coil (reactor) and an exterior member, can be manufactured using the resin composition of the above-mentioned this embodiment.
For example, a desired molded product can be produced by molding the resin composition of the present embodiment by various molding methods such as transfer molding, injection molding, extrusion molding, and press molding. In these molding methods, the resin composition melts and flows upon heating, and is molded into a desired shape.

In particular, the resin composition of the present embodiment is preferably molded by transfer molding. That is, as a method of producing a molded article, it is preferable to inject a molten material of the thermosetting resin composition of the present embodiment into a mold using a transfer molding apparatus and obtain a molded article in which the molten material is cured. . That is, the preheated resin composition is put into a heating chamber, which is also called a transfer chamber, and melted, and then poured into a mold with a plunger and held as it is to cure the resin, to obtain a desired molded product. be able to.
Transfer molding is preferable to other molding methods in terms of controllability of dimensions of molded products and improvement of shape freedom.

  Various conditions in transfer molding can be set arbitrarily. For example, the temperature for preheating is 60 to 100 ° C., the heating temperature in the heating chamber is 150 to 250 ° C., the mold temperature is 150 to 200 ° C., and the pressure for injecting the melt of the resin composition into the mold is 1 To 20 MPa.

<Coil>
An outline of a coil (reactor) including a magnetic core formed of a cured product of the resin composition of the present embodiment will be described with reference to FIG.
Fig.2 (a) shows the outline of the coil 100 seen from the upper surface. FIG.2 (b) shows the sectional view in the AA 'cross section view in FIG. 2 (a).

The coil 100 can comprise a winding 10 and a magnetic core 20, as shown in FIG. The magnetic core 20 is filled in the inside of the winding 10 which is an air core coil. The pair of windings 10 shown in FIG. 2A are connected in parallel. In this case, the annular magnetic core 20 has a structure penetrating the inside of the pair of windings 10 shown in FIG. 2 (b). The magnetic core 20 and the winding 10 can have an integrated structure.
In addition, the coil 100 may have a structure in which an insulator (not shown) is interposed between the winding 10 and the magnetic core 20 from the viewpoint of securing the insulation therebetween.

  In the coil 100, the winding 10 and the magnetic core 20 may be sealed by an exterior member 30 (a sealing member). For example, the winding 10 and the magnetic core 20 are accommodated in a case (case), the liquid resin is introduced into the case, and the liquid resin is cured if necessary, around the winding 10 and the magnetic core 20. The exterior member 30 may be formed. At this time, the winding 10 may have a drawing portion (not shown) in which the end of the winding is drawn to the outside of the exterior member 30.

  The winding 10 is usually configured by winding a winding having an insulating coating on the surface of a metal wire. The metal wire is preferably highly conductive, and copper and copper alloys can be suitably used. Also, as the insulation coating, a coating such as enamel can be used. The cross-sectional shape of the winding may be circular, rectangular, hexagonal or the like.

  On the other hand, the cross-sectional shape of the magnetic core 20 is not particularly limited, but can be, for example, a circular shape, or a polygonal shape such as a quadrangle or a hexagon in cross-sectional view. The magnetic core 20 is made of the transfer molded product of the resin composition of the present embodiment, and thus can have a desired shape.

  According to the cured product of the resin composition of the present embodiment, the magnetic core 20 excellent in moldability and magnetic properties can be realized. That is, it is expected that the coil 100 provided with the magnetic core 20 is suitable for mass production and that the iron loss is small. Moreover, since the magnetic core 20 excellent in mechanical characteristics can be realized, it is possible to enhance the durability, the reliability, and the manufacturing stability of the coil 100. For this reason, the coil 100 of the present embodiment can be used as a reactor for a booster circuit or a large current.

<Coil (another embodiment)>

As an aspect different from the above-described coil, an outline of a coil (inductor) including an exterior member formed of a cured product of the resin composition of the present embodiment will be described with reference to FIG.
FIG. 3A shows an outline of the coil as viewed from the top of the coil 100B. FIG.3 (b) shows the sectional view in the BB 'cross section view in FIG. 3 (a).

The coil 100B can comprise a winding 10B and a magnetic core 20B, as shown in FIG. The magnetic core 20B is filled inside the winding 10B which is an air core coil. The pair of windings 10B shown in FIG. 3A is connected in parallel. In this case, the annular magnetic core 20B has a structure penetrating the inside of the pair of windings 10B shown in FIG. 3 (b). The magnetic core 20B and the winding 10B can be individually prepared and have a combined structure combined.
The coil 100B may have a structure in which an insulator (not shown) is interposed between the winding 10B and the magnetic core 20B from the viewpoint of securing the insulation therebetween.

  In the coil 100B, the winding 10B and the magnetic core 20B are sealed by an exterior member 30B (a sealing member). For example, the magnetic core 20B filled in the winding 10B is disposed in a mold, and the resin composition of the present embodiment is cured by molding such as transfer molding, thereby curing the resin composition, The exterior member 30B can be formed around the winding 10B and the magnetic core 20B. At this time, the winding 10 </ b> B may have a drawing portion (not shown) in which the end portion of the winding is drawn out of the exterior member 30 </ b> B.

  The winding 10B is usually configured by winding a conducting wire having an insulating coating on the surface of a metal wire. The metal wire is preferably highly conductive, and copper and copper alloys can be suitably used. Also, as the insulation coating, a coating such as enamel can be used. The cross-sectional shape of the winding 10B may be circular, rectangular, hexagonal or the like.

  On the other hand, the cross-sectional shape of the magnetic core 20B is not particularly limited, but can be, for example, a circular shape, or a polygonal shape such as a quadrangle or a hexagon in cross-sectional view. For example, a dust core made of magnetic powder and a binder can be used as the magnetic core 20B.

  According to the cured product of the resin composition of the present embodiment, the exterior member 30B having excellent formability and high magnetic permeability and other magnetic characteristics can be realized, so low magnetic loss is expected in the coil 100B including the magnetic core 20B. Be done. Moreover, since the exterior member 30B excellent in mechanical characteristics can be realized, it is possible to enhance the durability, reliability, and manufacturing stability of the coil 100B.

<Coil (Integrated inductor)>
As still another aspect, an outline of an integrated inductor provided with a magnetic core and an exterior member formed of the cured product of the resin composition of the present embodiment will be described with reference to FIG.
FIG. 4A shows an outline of the structure viewed from the top of the integrated inductor 100C. FIG.4 (b) shows the sectional view in the CC 'cross section view in FIG. 4 (a).

  The integrated inductor 100C can include a winding 10C and a magnetic core 20C, as shown in FIG. The magnetic core 20C is filled inside C of the winding 10 which is an air core coil. The winding 10C and the magnetic core 20C are sealed by an exterior member 30C (sealing member). The magnetic core 20C and the exterior member 30C can be formed of a cured product of the resin composition of the present embodiment. The magnetic core 20C and the exterior member 30C may be formed as a seamless integral member.

  As a method of manufacturing the integrated inductor 100C, for example, the winding 10C is disposed in a mold, and molding such as transfer molding is performed using the resin composition of the present embodiment. As a result, the resin composition can be cured to integrally form the exterior member 30C around the magnetic cores 20C filled in the winding 10C and these. At this time, the winding 10C may have a not-shown drawing portion in which the end of the winding is drawn to the outside of the exterior member 30C.

  The winding 10C is usually configured by winding a conducting wire having an insulating coating on the surface of a metal wire. The metal wire is preferably highly conductive, and copper and copper alloys can be suitably used. Also, as the insulation coating, a coating such as enamel can be used. The cross-sectional shape of the winding 10C may be circular, rectangular, hexagonal or the like.

  On the other hand, the cross-sectional shape of the magnetic core 20C is not particularly limited, but can be, for example, a circular shape, or a polygonal shape such as a quadrangle or a hexagon in cross-sectional view. The magnetic core 20C is formed of the transfer molded product of the resin composition of the present embodiment, and thus can have a desired shape.

  According to the cured product of the resin composition of the present embodiment, the magnetic core 20C and the exterior member 30C excellent in magnetic properties such as moldability and high magnetic permeability can be realized. Magnetic loss is expected. Further, since the exterior member 30C having excellent mechanical characteristics can be realized, it is possible to enhance the durability, reliability, and manufacturing stability of the integrated inductor 100C. Therefore, the integrated inductor 100C can be used as an inductor for a booster circuit or for a large current.

<Thermosetting resin composition for transfer molding>
As described above, the thermosetting resin composition of the present embodiment is used to form the magnetic core and / or the exterior member of the coil.
On the other hand, as another aspect, the thermosetting resin composition of the present embodiment is preferably molded by transfer molding to form a molded article having a desired shape, not limited to the magnetic core and / or the exterior member of the coil. You can get it. That is, the thermosetting resin composition of the present embodiment may be "for transfer molding".

The reference embodiment when the thermosetting resin composition of the present embodiment is “for transfer molding” will be described below.
1.
A thermosetting resin composition for transfer molding, comprising:
Containing magnetic particles and thermosetting resin,
Assuming that the cumulative 10% value in the volume-based particle size distribution curve of the magnetic particles is D ₁₀ , the cumulative 50% value is D ₅₀ , and the cumulative 90% value is D ₉₀ , the D ₅₀ value is 5 to 30 μm the thermosetting resin composition the value of _D 90 _{/ D 10} is 25 to 50.
2.
1. A thermosetting resin composition as described in
The thermosetting resin composition in which the said particle diameter distribution curve has a maximum in the area | region of particle diameter 1-3 micrometers, and the area | region of particle diameter 20-45 micrometers.
3.
1. Or 2. A thermosetting resin composition as described in
The thermosetting resin composition whose content of the said magnetic body particle | grains is 95 mass% or more with respect to the whole solid content of a composition.
4.
1. ~ 3. A thermosetting resin composition according to any one of
A thermosetting resin composition, wherein the magnetic particles contain one or more elements selected from the group consisting of iron, chromium, cobalt, nickel, silver and manganese.
5.
1. ~ 4. A thermosetting resin composition according to any one of
Thermosetting resin containing magnetic particles having an average circularity of 0.60 or more, which is obtained by determining the roundness defined below for any ten or more of the magnetic particles and averaging the values. Composition.
[Definition of roundness]
The value of Req / Rc when the contour of the magnetic particles is observed with a scanning electron microscope, where the equivalent circular equivalent diameter determined from the contour is Req and the radius of the circle circumscribing the contour is Rc.
6.
1. To 5. A thermosetting resin composition according to any one of
A thermosetting resin composition, wherein the thermosetting resin comprises an epoxy resin.
7.
6. A thermosetting resin composition as described in
The thermosetting resin composition in which the said epoxy resin contains the compound represented by the general formula (I) shown above.
(In the general formula (I), two R's each independently represent a hydrogen atom or an alkyl group.)
8.
1. ~ 7. A thermosetting resin composition according to any one of
A thermosetting resin composition containing a curing agent for the thermosetting resin.
9.
8. A thermosetting resin composition as described in
A thermosetting resin composition, wherein the curing agent comprises a phenolic curing agent.
10.
1. ~ 9. A thermosetting resin composition according to any one of
A thermosetting resin composition having a flow length of 50 cm or more as measured by a spiral flow test at a temperature of 175 ° C.
11.
1. To 10. A thermosetting resin composition according to any one of
When a test is conducted to maintain a cured molded product produced by heating and melting the thermosetting resin composition at 175 ° C. for 4 hours, the length in the longitudinal direction of the cured molded product before the test is L _A thermosetting resin composition in which the dimensional shrinkage ratio represented by (L ₁ / L ₀ ) × 100 is 1% or less, where ₀ is the thermal shrinkage of the cured molded product after the test is L ₁ . .
12.
1. -12. The molded article comprised with the hardened | cured material of the thermosetting resin composition as described in any one of these.
13.
Using a transfer molding apparatus: -12. The manufacturing method of the molded article which inject | pours the melt of the thermosetting resin composition as described in any one of these in a metal mold | die, and obtains the molded article which the said melt hardened.

  As mentioned above, although embodiment of this invention was described, these are the illustrations of this invention, and various structures other than the above can be employ | adopted. Furthermore, the present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the scope in which the object of the present invention can be achieved are included in the present invention.

  Embodiments of the present invention will be described in detail based on examples and comparative examples. The present invention is not limited to the examples.

<Preparation of Resin Composition>
The resin composition was prepared as follows about each of each Example. First, each raw material component was mixed by a mixer according to the raw material component shown in Table 1 and its compounding ratio. Next, the resulting mixture is roll-kneaded, cooled, crushed, and tableted to obtain a tablet-like resin composition.
Specifically, the raw material components shown in Table 1 are as follows. Note that the value of D ₅₀ of the iron-based particles 1-6 is the value provided by the manufacturer, supplier. Moreover, roundness was calculated | required by the below-mentioned measurement.

(Magnetic particles)
Iron-based particles 1: Amorphous magnetic powder (manufactured by Epson Atmix Co., Ltd., KUAMET 6B2, D ₅₀ : 25 μm, roundness: 0.88)
Iron-based particles 2: carbonyl iron powder (manufactured by BASF, CIP-HQ, D ₅₀ : 2 μm, roundness: 0.90)
Iron-based particles 3: amorphous magnetic powder (manufactured by Epson Atmix Co., Ltd., KUAMET 6B2, D ₅₀ : 50 μm, roundness: 0.85)
Iron-based particles 4: alloy steel powder (Daido Specialty Steel Co., Ltd., DAPMSC5, D ₅₀ : 10 μm, roundness: 0.80)
Iron-based particles 5: Iron alloy powder (manufactured by Sanyo Special Steel Co., Ltd., PST-S, D ₅₀ : 25 μm, roundness: 0.89)
Iron-based particles 6: Amorphous magnetic powder (manufactured by Epson Atmix Co., Ltd., KUAMETNC1, D ₅₀ : 25 μm, roundness: 0.86)

(Thermosetting resin)
Epoxy resin 1: Epoxy resin (Mitsubishi Chemical Corporation, trisphenylmethane type epoxy resin, E1032H60, solid at room temperature 25 ° C.)
Epoxy resin 2: Epoxy resin (manufactured by Mitsubishi Chemical Corporation, bisphenol A epoxy resin, YL 6810, solid at room temperature 25 ° C.)
The epoxy resin 2 corresponds to a compound in which two R's are both methyl groups in the above general formula (I).

(Hardening agent)
Phenolic resin: Novolak type phenolic resin (manufactured by Sumitomo Bakelite Co., Ltd., PR-HF-3, solid at room temperature 25 ° C.)

(Release agent)
Release agent: Synthetic wax (manufactured by Clariant Chemicals, Inc., ester wax WE-4)

(Hardening accelerator)
Imidazole-based curing accelerator: Imidazole-based curing accelerator (manufactured by Shikoku Kasei Kogyo Co., Ltd., Cuazole 2PZ-PW)

(Particle diameter distribution of magnetic particles)
By dry-measuring magnetic particles (not including other components such as thermosetting resin) contained in each resin composition of Table 1 with a particle size distribution measuring apparatus “LA-950” manufactured by HORIBA, A volume based particle size distribution curve was obtained.

The values of D ₁₀ , D ₅₀ and D ₉₀ , the values of D ₉₀ / D ₁₀ , the maximum positions, S ₁ , S ₂ and S ₁ / S ₂ obtained from the obtained particle size distribution curve are shown in Table 2 Show.
In Table 2, the values of S ₁ and S ₂ are relative values when the area of the entire particle size distribution curve is 100.
In addition, about each "maximum position", in each Example and a comparative example, it did not exist except the position described in Table 2 (that is, two maximums in Example 1-3 and comparative example 2, and a comparative example) The maximum was 1 in 1).

(Average roundness of magnetic particles)
It asked by the following procedures.
(1) Arbitrary ten of the magnetic particles contained in the resin composition of each example were selected, and the contours of the selected particles were observed with a scanning electron microscope.
(2) For each particle observed, the equivalent circular equivalent diameter Req and the radius Rc of the circle circumscribing the contour were determined from the contour, and the value of Req / Rc (roundness of each particle) was calculated.
(3) The average roundness was determined by averaging the values of Req / Rc of each particle.

<Performance evaluation>
The resin compositions obtained in the above Examples and Comparative Examples were evaluated based on the following evaluation items.

(Flowability: Spiral flow test)
The spiral flow test was performed using the resin composition of each Example and a comparative example.
In the test, using a low-pressure transfer molding machine ("KTS-15" manufactured by Kotaki Seiki Co., Ltd.), mold temperature for the spiral flow measurement according to EMMI-1-66, mold temperature 175 ° C., injection pressure 6 .9 MPa, and the resin composition for sealing was injected under the condition of curing time of 120 seconds, and the flow length was measured.
The results are shown in Table 3. The larger the value, the better the fluidity.

(Iron loss (50 mT, 50 kHz))
The resin composition of each of the examples and comparative examples was subjected to a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, and a curing time of 120 seconds using a low-pressure transfer molding machine (“KTS-30” manufactured by Kotaki Seiki Co., Ltd.) Injection molding was performed to obtain a ring-shaped molded article having an outer diameter of 27 mm and an inner diameter of 15 mm and a thickness of 3 mm. Then, the obtained ring-shaped molded article was post-cured at 175 ° C. for 4 hours.
With respect to the ring-shaped test piece thus obtained, a hysteresis loss Wh (excitation magnetic flux density Bm: 50 mT, measurement frequency: 50 kHz) using an AC / DC magnetization characteristic recording apparatus (MTR-3368 manufactured by Metron Giken Co., Ltd.) The kW / m ³ ) and the eddy current loss We (kW / m ³ ) were measured. Then, the sum of the hysteresis loss Wh and the eddy current loss We was calculated as an iron loss (kW / m ³ ).
The evaluation results are shown in Table 3. The smaller the value, the better the performance.

(Shrinkage factor)
The resin composition of each Example and Comparative Example was subjected to a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, and a curing time of 120 seconds using a low-pressure transfer molding machine (“KTS-30” manufactured by Kotaki Seiki Co., Ltd.) Injection molding was performed under the conditions. Thereafter, it was allowed to cool, and a circular shaped molded product for measuring the shrinkage factor of 100 mm in diameter and 3 mm in thickness was obtained. The diameter of the molded article was accurately measured and recorded.
The above molded article was then heat treated in an oven maintained at a temperature of 175 ° C. for 4 hours and then cooled to room temperature. The diameter of the cooled molding was accurately measured and recorded.
From the diameter L ₀ of the molded product before heat treatment and the shrinkage L ₁ of the diameter of the molded product after heat treatment and cooling,
Formula: (L ₁ / L ₀ ) × 100
The thermal contraction rate was calculated by This value is described in Table 3.

(Melt viscosity (175 ° C))
As a measuring apparatus, a heightening type flow tester (CFT-500D manufactured by Shimadzu Corporation) equipped with a die having a diameter of 0.5 mm and a length of 10 mm was used.
Under the conditions of a measurement temperature of 175 ° C. and a load of 40 kgf, the obtained resin composition was charged into the apparatus to determine the minimum viscosity. The measurement was performed three times, and the average value of three times was taken as the melt viscosity (Pa · s) at 175 ° C.
The obtained values are listed in Table 3.

As shown from Table 3 etc., the resin composition of Examples 1 to 3 using magnetic particles in which the value of D ₅₀ is in the range of 5 to 30 μm and the value of D ₉₀ / D ₁₀ is in the range of 25 to 50 The product had a large amount of spiral flow and a small iron loss. That is, it was shown that the magnetic properties were good and the fluidity at the time of molding was good.
Looking at the examples in more detail, Examples 1 and 3 in which the value of D ₉₀ / D ₁₀ is in the range of 32 to 48 are better than Example 2 in which the value of D ₉₀ / D ₁₀ is 26.9. The results are good for both the spiral flow rate and the iron loss.

On the other hand, as in the comparative example, when the value of D ₉₀ / D ₁₀ is small or when the value of D ₅₀ is large, the magnetic properties are worse at least as compared with Examples 1 to 3, and the fluidity at the time of molding It was bad too.
In the resin composition of Comparative Example 1, the fluidity was too low (the spiral flow amount was 0), and the iron loss and the like could not be evaluated.

10 winding 20 magnetic core 30 exterior member 100 coil 10B winding 20B magnetic core 30B exterior member 100B coil 10C winding 20C magnetic core 30C exterior member 100C integrated inductor

Claims (14)

A thermosetting resin composition for forming a magnetic core and / or an exterior member of a coil, comprising:
Containing magnetic particles and thermosetting resin,
Assuming that the cumulative 10% value in the volume-based particle size distribution curve of the magnetic particles is D ₁₀ , the cumulative 50% value is D ₅₀ , and the cumulative 90% value is D ₉₀ , the D ₅₀ value is 5 to 30 μm the thermosetting resin composition the value of _D 90 _{/ D 10} is 25 to 50. It is a thermosetting resin composition according to claim 1, which is
The thermosetting resin composition in which the said particle diameter distribution curve has a maximum in the area | region of particle diameter 1-3 micrometers, and the area | region of particle diameter 20-45 micrometers. It is a thermosetting resin composition according to claim 1 or 2,
The thermosetting resin composition whose content of the said magnetic body particle | grains is 95 mass% or more with respect to the whole solid content of a composition. The thermosetting resin composition according to any one of claims 1 to 3, which is
A thermosetting resin composition, wherein the magnetic particles contain one or more elements selected from the group consisting of iron, chromium, cobalt, nickel, silver and manganese. It is a thermosetting resin composition of any one of Claims 1-4,
Thermosetting resin containing magnetic particles having an average circularity of 0.60 or more, which is obtained by determining the roundness defined below for any ten or more of the magnetic particles and averaging the values. Composition.
[Definition of roundness]
The value of Req / Rc when the contour of the magnetic particles is observed with a scanning electron microscope, where the equivalent circular equivalent diameter determined from the contour is Req and the radius of the circle circumscribing the contour is Rc. It is a thermosetting resin composition of any one of Claims 1-5, Comprising:
A thermosetting resin composition, wherein the thermosetting resin comprises an epoxy resin. It is a thermosetting resin composition according to claim 6, which is
The thermosetting resin composition in which the said epoxy resin contains the compound represented by the following general formula (I).

In general formula (I), two R's each independently represent a hydrogen atom or an alkyl group. The thermosetting resin composition according to any one of claims 1 to 7, which is
A thermosetting resin composition containing a curing agent for the thermosetting resin. It is a thermosetting resin composition according to claim 8, which is
A thermosetting resin composition, wherein the curing agent comprises a phenolic curing agent. The thermosetting resin composition according to any one of claims 1 to 9, which is
A thermosetting resin composition having a flow length of 50 cm or more as measured by a spiral flow test at a temperature of 175 ° C. The thermosetting resin composition according to any one of claims 1 to 10, wherein
When a test is conducted to maintain a cured molded product produced by heating and melting the thermosetting resin composition at 175 ° C. for 4 hours, the length in the longitudinal direction of the cured molded product before the test is L _A thermosetting resin composition in which the dimensional shrinkage ratio represented by (L ₁ / L ₀ ) × 100 is 1% or less, where ₀ is the thermal shrinkage of the cured molded product after the test is L ₁ . . It is a thermosetting resin composition according to any one of claims 1 to 11,
A thermosetting resin composition used to form a magnetic core of a coil.   The coil provided with the magnetic core and / or the exterior member comprised with the hardened | cured material of the thermosetting resin composition of any one of Claims 1-12.   Production of a molded article, wherein the melt of the thermosetting resin composition according to any one of claims 1 to 12 is injected into a mold using a transfer molding apparatus, and a molded article obtained by curing the melt is obtained. Method.

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