JP2023108807A - Resin molding material, molding and method for producing molding - Google Patents

Abstract

To provide a resin molding material that has excellent moldability and can be excellently filled into a die or the like in a molding process at low temperatures such as transfer molding or compression molding.SOLUTION: A resin molding material is used in transfer molding or compression molding, the resin molding material comprising (A) an epoxy resin, (B) a curing agent, (C) an imidazole catalyst having a C3-20 long-chain hydrocarbon group, and (D) soft magnetic particles.SELECTED DRAWING: None

Description

The present invention relates to a resin molding material, a molded article, and a method for producing the molded article.

In recent years, as electronic devices have become smaller and lighter, there has been a demand for resin molding materials containing magnetic particles with high moldability. Magnetic particles are classified into two types: soft magnetic particles and hard magnetic particles.
Patent Literature 1 discloses a resin composition for a powder magnetic core containing a trifunctional or higher polyfunctional epoxy resin, a bifunctional epoxy resin, and metal magnetic powder. The document is a technique of compacting the resin composition. Contains at least 100 to 50 parts by weight of a 1-azine-2-undecylimidazole polyfunctional epoxy resin and 0 to 50 parts by weight of a bifunctional epoxy resin having two p-(2,3-epoxypropoxy)phenyl groups A resin composition for a dust core containing 0.5 to 8.0% by weight of a thermosetting resin composition and (B) 99.5 to 92.0% by weight of a metal magnetic powder treated with an inorganic insulating coating.

Patent Literature 2 discloses a resin composition containing soft magnetic powder, solid resin, liquid resin, and a curing accelerator having a melting point of 120° C. or higher and 245° C. or lower. The document describes a curing accelerator having a triazine skeleton as the curing accelerator.

Patent Document 3 discloses a compound containing metal element-containing powder, an epoxy resin, and a compound having a siloxane bond. The document describes that an imidazole-based curing accelerator may be included. Also, an example of transfer molding under conditions of a mold temperature of 175° C. is described.

JP-A-9-102409 JP 2021-70795 A WO2021/112135

In recent years, the number of parts that are vulnerable to high temperatures has increased, and materials that can be used in transfer molding or compression molding at low temperatures (about 100 to 150° C.) are in demand.
However, when the temperature during molding is low, the viscosity of the molding material increases and the fluidity decreases, so there is room for improvement in moldability. In the conventional techniques described in Patent Documents 2 and 3, unfilled portions may occur in the mold during the molding process at a low temperature, leaving room for improvement in moldability.

The present inventors have found that the use of a specific imidazole catalyst in a resin molding material containing soft magnetic particles improves moldability in a low-temperature molding process such as transfer molding or compression molding, and completed the present invention. let me
That is, the present invention can be shown below.

According to the invention,
A resin molding material used for transfer molding or compression molding,
(A) an epoxy resin;
(B) a curing agent;
(C) an imidazole catalyst containing a long-chain hydrocarbon group having 3 to 20 carbon atoms;
(D) Soft magnetic particles are provided.

According to the invention,
A molded product obtained by curing the resin molding material is provided.

According to the invention,
A step of injecting the melt of the resin molding material into a mold using a transfer molding device;
curing the melt at 100° C. to 150° C.;
A method of manufacturing a molded article is provided, comprising:

According to the invention,
A method for producing a molded article is provided, which includes a step of compression molding the resin molding material at 100°C to 150°C.

According to the present invention, it is possible to provide a resin molding material which is excellent in fillability into a mold or the like in a molding process at a low temperature such as transfer molding or compression molding, and which is excellent in moldability.

It is a sectional view showing composition of a structure concerning this embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In addition, in all the drawings, the same constituent elements are denoted by the same reference numerals, and the description thereof will be omitted as appropriate. Also, for example, "1 to 10" represents "1 or more" to "10 or less" unless otherwise specified.

The resin molding material of the present embodiment is a resin molding material used for transfer molding or compression molding, comprising (A) an epoxy resin, (B) a curing agent, and (C) a long-chain carbonization of 3 to 20 carbon atoms. An imidazole catalyst containing hydrogen groups, and (D) soft magnetic particles.

[Epoxy resin (A)]
As the epoxy resin (A), known epoxy resins can be used as long as the effects of the present invention are exhibited.

Examples of the epoxy resin (A) include bisphenol A type epoxy resin, bisphenol F type epoxy resin, tetramethylbisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol E type epoxy resin, bisphenol M type epoxy resin, and bisphenol P type epoxy resin. Bisphenol-type epoxy resins such as epoxy resins and bisphenol Z-type epoxy resins; novolac-type epoxy resins such as phenol novolac-type epoxy resins and cresol novolak-type epoxy resins; biphenyl-type epoxy resins, biphenylaralkyl-type epoxy resins, arylalkylene-type epoxy resins, 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, trisphenylmethane type epoxy resin, Zyloc type epoxy resin, etc. can be mentioned.

The resin molding material of the present embodiment may contain only one type of epoxy resin, or may contain two or more types. In addition, epoxy resins of the same type but different molecular weights may be used together.

From the viewpoint of the effect of the present invention, the epoxy resin (A) of the present embodiment includes bisphenol A type epoxy resin, trisphenylmethane type epoxy resin, biphenylaralkyl type epoxy resin, cresol novolak type epoxy resin, Zyloc type epoxy resin, and It is preferably at least one selected from biphenyl-type epoxy resins, more preferably triphenylmethane-type epoxy resins, biphenylaralkyl-type epoxy resins and cresol novolac-type epoxy resins, and still more preferably biphenylaralkyl-type epoxy resins.

A triphenylmethane-type epoxy resin is, specifically, an epoxy resin containing a partial structure in which three of the four hydrogen atoms of methane (CH ₄ ) are substituted with benzene rings. The benzene ring may be unsubstituted or substituted with a substituent. Examples of substituents include a hydroxy group and a glycidyloxy group.

Specifically, the triphenylmethane-type epoxy resin contains a structural unit represented by general formula (a1) below. A triphenylmethane skeleton is formed by connecting two or more of these structural units.

In general formula (a1),
R ¹¹ , when there are more than one, is each independently a monovalent organic group, a halogen atom, a hydroxy group or a cyano group;
R ¹² is each independently a monovalent organic group, a halogen atom, a hydroxy group or a cyano group when there are more than one,
i is an integer from 0 to 3,
j is an integer from 0 to 4;

Examples of monovalent organic groups for R ¹¹ and R ¹² include those listed as monovalent organic groups for R ^a and R ^b in general formula (BP) described later.
i and j are each independently preferably 0-2, more preferably 0-1.

In one aspect, both i and j are zero. That is, as one aspect, none of the benzene rings in general formula (a1) has any substituent other than the specified glycidyloxy group as a monovalent substituent.

An epoxy resin containing a biphenyl structure is specifically an epoxy resin containing a structure in which two benzene rings are linked by a single bond. The benzene ring here may or may not have a substituent.
Specifically, an epoxy resin containing a biphenyl structure has a partial structure represented by general formula (BP) below.

In the general formula (BP),
R ^a and R ^b are each independently a monovalent organic group, a hydroxyl group or a halogen atom when there are more than one;
r and s are each independently 0 to 4;
* indicates that it is connected to another atomic group.

Specific examples of monovalent organic groups for R ^a and R ^b include alkyl groups, alkenyl groups, alkynyl groups, alkylidene groups, aryl groups, aralkyl groups, alkaryl groups, cycloalkyl groups, alkoxy groups, heterocyclic groups, and carboxyl groups. and the like.

Examples of alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group and the like.
Alkenyl groups include, for example, allyl groups, pentenyl groups, and vinyl groups.
Examples of alkynyl groups include ethynyl groups.
The alkylidene group includes, for example, a methylidene group and an ethylidene group.
Aryl groups include, for example, tolyl, xylyl, phenyl, naphthyl, and anthracenyl groups.
The aralkyl group includes, for example, a benzyl group and a phenethyl group.
Examples of the alkaryl group include tolyl group and xylyl group.
Cycloalkyl groups include, for example, adamantyl, cyclopentyl, cyclohexyl, and cyclooctyl groups.

Examples of alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, s-butoxy, isobutoxy, t-butoxy, n-pentyloxy, and neopentyloxy groups. , n-hexyloxy group and the like.
Heterocyclic groups include, for example, an epoxy group and an oxetanyl group.

The total carbon number of the monovalent organic groups of R ^a and R ^b is, for example, 1 to 30, preferably 1 to 20, more preferably 1 to 10, and particularly preferably 1 to 6, respectively.
r and s are each independently preferably 0-2, more preferably 0-1. In one aspect, r and s are both zero.

More specifically, the epoxy resin containing a biphenyl structure is preferably a biphenyl aralkyl type epoxy resin having a structural unit represented by general formula (BP1) below.

In general formula (BP1),
The definitions and specific embodiments of R ^a and R ^b are the same as in general formula (BP),
The definitions and preferred ranges of r and s are the same as in general formula (BP),
R ^c is each independently a monovalent organic group, a hydroxyl group or a halogen atom when there are more than one;
t is an integer from 0 to 3;
Specific examples of the monovalent organic group for R ^c are the same as the specific examples for R ^a and R ^b .
t is preferably 0-2, more preferably 0-1.

The amount of epoxy resin in the resin molding material of this embodiment is, for example, 0.1 to 10% by mass, preferably 0.5 to 5% by mass.
The amount of epoxy resin in the resin molding material of this embodiment is, for example, 0.5 to 30% by volume, preferably 3 to 20% by volume.

[Curing agent (B)]
The curing agent (B) is not particularly limited as long as it can react with the epoxy group of the epoxy resin (A) to form a bond. For example, aliphatic polyamines, aromatic polyamines, aromatic diamines, amine compounds such as dicyaminediamide, alicyclic acid anhydrides, acid anhydrides such as aromatic acid anhydrides, phenols such as novolak-type phenolic resins compounds, imidazole compounds, and the like. Among these, specific curing agents that are solid at 23°C can be mentioned.

The curing agent (B) preferably contains a phenol-based curing agent (phenol compound) as a particular curing agent. As a result, a further improvement in the durability of the final molded product can be expected. Phenolic curing agents typically have two or more hydroxy groups per molecule.

The phenolic curing agent preferably contains any skeleton selected from the group consisting of a novolac skeleton and a biphenyl skeleton. Including one of these skeletons in the phenol-based curing agent can particularly enhance the durability of the molded article.
Specifically, the "biphenyl skeleton" is a structure in which two benzene rings are linked by a single bond, as in the general formula (BP) in the explanation of the epoxy resin described above.

Specific examples of the phenol-based curing agent having a biphenyl skeleton include biphenyl aralkyl type in which the glycidyl group is replaced with a hydrogen atom in the general formula (BP1) in the above description of the epoxy resin.
Specific examples of the phenol-based curing agent having a novolak skeleton include those having a structural unit represented by the following general formula (N).

In the general formula (N),
R ⁴ represents a monovalent substituent,
u is an integer from 0 to 3;
Specific examples of the monovalent substituent for R ⁴ are the same as those described as the monovalent substituents for R ^a and R ^b in general formula (BP).
u is preferably 0 to 2, more preferably 0 to 1, still more preferably 0.

In the present embodiment, the phenolic curing agent is preferably at least one selected from novolak-type phenolic resins, biphenylaralkyl-type phenolic resins and Zyloc-type phenolic resins, more preferably biphenylaralkyl-type phenolic resins. .

When the phenolic curing agent is a polymer or oligomer, the number average molecular weight of the phenolic curing agent (converted to standard polystyrene by GPC measurement) is, for example, about 200-800.

The content of the phenol curing agent in the resin molding material is, for example, 0.1 to 20% by mass, preferably 0.5 to 10% by mass.
Also, the content of the phenol curing agent in the resin molding material is, for example, 0.5 to 60% by volume, preferably 3 to 40% by volume.

By appropriately adjusting the amount of the phenol curing agent, the fluidity can be further improved, and the mechanical properties and magnetic properties of the resulting cured product can be improved.

In the present embodiment, at least one of the epoxy resin (A) and the phenolic curing agent has a biphenyl aralkyl structure, and preferably both of them have a biphenyl aralkyl structure, from the viewpoint of the effect of the present invention, particularly from the viewpoint of mold filling. It has an aralkyl structure.
In the resin molding material of the present embodiment, since at least one of the epoxy resin (A) and the phenolic curing agent contains a biphenylaralkyl structure, the reactivity can be reduced in the molding process at a low temperature. The melt viscosity can be lowered more stably. That is, such a resin molding material is excellent in fillability into a mold or the like, and is excellent in moldability.

The equivalent ratio (b/c) of the epoxy equivalent b of the epoxy resin (A) to the phenolic hydroxyl equivalent c of the phenol curing agent is 0.7 or more and 5.0 or less, preferably It can be 0.8 or more and 4.0 or less, more preferably 0.9 or more and 3.0 or less, and still more preferably 1.0 or more and 2.0 or less.

[Imidazole catalyst (C)]
The imidazole catalyst (C) contains a long-chain hydrocarbon group having 3 to 20 carbon atoms at its end. The number of carbon atoms in the long-chain aliphatic group is preferably 5-20, more preferably 8-18, still more preferably 10-18.
By containing the imidazole catalyst (C) containing the group, the melt viscosity of the resin molding material is lowered, and the molding process at low temperature such as transfer molding or compression molding is excellent in fillability into molds, etc., and moldability is improved. Excellent.
Furthermore, since the imidazole catalyst (C) containing the group is incorporated into the curing system, it is possible to provide a cured product having excellent mechanical strength such as bending strength.

The imidazole catalyst (C) preferably contains a compound represented by the following general formula (1).

In general formula (1), R represents a saturated or unsaturated long-chain aliphatic group having 3 to 20 carbon atoms. The number of carbon atoms in the long-chain aliphatic group is preferably 5-20, more preferably 8-18, still more preferably 10-18.
Saturated or unsaturated long-chain aliphatic groups include, for example, alkyl groups, aralkyl groups, alkenyl groups, alkynyl groups, and the like. Examples of saturated or unsaturated aliphatic groups include alkyl groups, aralkyl groups, alkenyl groups, alkynyl groups, and the like.

Q represents a cyano group or an optionally substituted triazinyl group. Substituents for the substituted triazinyl group include an amino group, an alkyl group having 1 to 5 carbon atoms, a halogen atom and the like, preferably an amino group.
n represents an integer of 1-5, preferably 1-3.

The imidazole catalyst (C) more preferably contains a compound having a triazine skeleton in its structure. As a result, the activation temperature of the imidazole catalyst (C) increases, and a resin molding material more suitable for molding processes at low temperatures (about 100 to 150° C.) can be provided.

The content of the imidazole catalyst (C) in the resin molding material is, for example, 0.02-1.0% by mass, preferably 0.05-0.5% by mass.
Also, the content of the imidazole catalyst (C) in the resin molding material is, for example, 0.05 to 3.0% by volume, preferably 0.15 to 1.5% by volume.

[Soft magnetic particles (D)]
Soft magnetism refers to ferromagnetism with a small coercive force, and in general, ferromagnetism with a coercive force of 800 A/m or less is called soft magnetism.
The soft magnetic particles (D) preferably contain iron-based particles. Iron-based particles refer to particles whose main component is iron atoms (the mass content of iron atoms is the largest in the chemical composition), more specifically, the mass content of iron atoms is the largest in the chemical composition. Refers to iron alloys.

The iron-based particles may include iron-based amorphous particles and may be composed of only iron-based amorphous particles, or may include iron-based amorphous particles and iron-based crystalline particles. As the iron-based particles, one having one chemical composition may be used, or two or more different chemical compositions may be used in combination.

The iron-based amorphous particles may have an amorphous phase inside the particles, and may be partially or wholly composed of an amorphous phase.
In the iron-based amorphous particles, the amorphous phase with respect to all phases in one particle may be, for example, 80% or more, preferably 90% or more, more preferably 100% by volume.

More specifically, particles exhibiting soft magnetism and having an iron atom (Fe) content of 85% by mass or more (soft magnetic iron-rich particles) can be used as the iron-based particles.

Examples of the constituent material of the soft magnetic particles (D) include metal-containing materials having an iron content of 85% by mass or more as a constituent element. 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, it is possible to obtain a resin molding material that can exhibit good magnetic properties when molded into a magnetic core or the like.

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

Moreover, the above metal-containing 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. In this embodiment, one or more elements selected from Fe, Ni, Si and Co can be included as main elements.

Specific examples of the metal-containing 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. Silicon steel and carbonyl iron can be preferably used from the viewpoint of availability.
The soft magnetic particles (Fe-based soft magnetic particles) may be other particles. For example, magnetic particles including Ni-based soft magnetic particles, Co-based soft magnetic particles, and the like may be used.

The volume-based median diameter D ₅₀ of the soft magnetic particles (D) is preferably 0.5 to 75 μm, more preferably 0.75 to 65 μm, still more preferably 1 to 60 μm. By appropriately adjusting the particle diameter (median diameter), the fluidity during molding can be further improved, and the magnetic performance can be improved.

_D50 can be obtained, for example, with a laser diffraction/scattering particle size distribution analyzer. Specifically, a particle size distribution curve is obtained by measuring the soft magnetic particles (D) in a dry manner using a particle size distribution measuring device "LA-950" manufactured by HORIBA, and by analyzing this distribution curve, D ₅₀ can be obtained.

The resin molding material of the present embodiment contains soft magnetic particles (D) in an amount of preferably 85% by mass or more, more preferably 90% by mass or more, and even more preferably 93% by mass or more. Although the upper limit is not particularly limited, it can be less than 100% by mass, preferably 98% by mass or less.
The resin molding material of the present embodiment contains soft magnetic particles (D) in an amount of preferably 70% by volume or more, more preferably 75% by volume or more, and even more preferably 80% by volume or more. Although the upper limit is not particularly limited, it can be 85% by volume or less, preferably 83% by volume or less. A magnetic material having a high saturation magnetic flux density can thus be obtained.

Since the resin molding material of the present embodiment uses an imidazole catalyst (C) containing a long-chain hydrocarbon group with 3 to 20 carbon atoms even if it contains the above amount of soft magnetic particles (D), In a molding process at a low temperature, it is possible to provide a resin molding material which is excellent in fillability into a mold or the like and which is excellent in moldability. That is, by using a predetermined imidazole catalyst (C), it is possible to provide a resin molding material having excellent balance between magnetic properties and moldability, which are in a trade-off relationship.

[Dispersant (E)]
The resin molding material of this embodiment can further contain a dispersant (E).
As the dispersing agent (E), a known dispersing agent can be used as long as the effect of the present invention is exhibited, but preferably a linear fatty acid having 8 to 20 carbon atoms (E1) is included.
In the present embodiment, by including the fatty acid (E1) together with the imidazole catalyst (C), the melt viscosity is further reduced, and a resin molding material is provided which is more excellent in fillability into a mold or the like in a molding process at a low temperature. can do.
From the viewpoint of the effect, the fatty acid (E1) is 30 parts by mass or more and 200 parts by mass or less, 50 parts by mass or more and 150 parts by mass or less, or 70 parts by mass or more and 120 parts by mass or less with respect to 100 parts by mass of the imidazole catalyst (C). can be contained in an amount of

The linear carbon number of the fatty acid (E1) is preferably 8 to 18, more preferably 10 to 18, still more preferably 12 to 18, from the viewpoint of the effects of the present invention.
It is thought that the carboxyl group of the fatty acid (E1) is bonded to the surface of the soft magnetic particles (D), and if the number of carbon atoms in the straight chain is within the above range, the dispersibility between the soft magnetic particles improves, and the resin molding material It is thought that the melt viscosity of

The melting point of the fatty acid (E1) is preferably 78°C or lower, more preferably 75°C or lower, and even more preferably 73°C or lower. Although the lower limit of the melting point is not particularly limited, it is about 5°C or higher. It is believed that when the melting point of the fatty acid (E1) is within this range, the fluidity of the soft magnetic particles is improved and the melt viscosity of the resin molding material is lowered in the low-temperature molding process.

Fatty acids (E1) include caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, pentadecyl acid, palmitic acid, palmitoleic acid, margaric acid, stearic acid, oleic acid, paxenoic acid, linoleic acid, and eleostearic acid. , arachidic acid, etc., and can contain at least one selected from these.
From the viewpoint of the effect of the present invention, the fatty acid (E1) is preferably lauric acid, stearic acid or oleic acid, more preferably stearic acid.

The content of fatty acid (E1) in the resin molding material is, for example, 0.01 to 5% by mass, preferably 0.05 to 3% by mass.
The content of fatty acid (E1) in the resin molding material is, for example, 0.05 to 5% by volume, preferably 0.2 to 2% by volume.

In this embodiment, the dispersant (E) can contain a carboxylic acid-based dispersant or the like as a dispersant other than the fatty acid (E1).
As the carboxylic acid dispersant, Hypermer KD-4 (mass average molecular weight: 1700, acid value: 33 mgKOH/g) and Hypermer KD-9 (mass average molecular weight: 760, acid value: 74 mgKOH/g) manufactured by CRODA. , Hypermer KD-16 (mass average molecular weight: 370, acid value: 299 mgKOH/g).

[Other ingredients]
The resin molding material of the present embodiment may contain components other than the components described above. For example, one or more of silane coupling agents, mold release agents, low stress agents, adhesion aids, colorants, antioxidants, anti-corrosion agents, dyes, pigments, flame retardants and the like may be included.

(Form of resin molding material)
At 23° C., the resin molding material of the present embodiment is preferably in the form of tablets or granules, and more preferably in the form of tablets. Since the resin molding material is in the form of tablets or granules, the resin molding material can be easily distributed and stored, and can be easily applied to transfer molding and compression molding.

(Manufacturing method of resin molding material)
Industrially, for example, the resin molding material of the present embodiment can be produced by, for example, first (1) mixing each component using a mixer, (2) then using a roll at around 90° C. for 5 minutes or more, preferably It can be produced by kneading for about 10 minutes to obtain a kneaded material, (3) cooling the obtained kneaded material, and (4) further pulverizing after that. As described above, a powdery resin molding material can be obtained. From the viewpoint of the effects of the present invention, the magnetic particles may be treated in advance with the compound of formula (1) before being mixed.

A powdered resin molding material may be tableted into granules or tablets. As a result, a resin molding material particularly suitable for use in transfer molding and compression molding can be obtained. The resin molding material of this embodiment is a low temperature curable material at 100°C to 150°C.

The resin molding material of the present embodiment has a low melt viscosity. s or less, more preferably 100 Pa·s or more and 800 Pa·s or less, still more preferably 120 Pa·s or more and 700 Pa·s or less, and particularly preferably 150 Pa·s or more and 600 Pa·s or less.

<Molded product>
The molded article of this embodiment can be obtained by curing the resin molding material described above.
Since the molded product of the present embodiment is composed of a composite material having a high saturation magnetic flux density as described above, a high saturation magnetic flux density can be realized, and is 1.0 T or more, preferably 1.2 T or more, more preferably 1.2 T or more. can be greater than or equal to 1.3T.

<Method for manufacturing molded product>
The method for producing the molded article is not particularly limited, but examples thereof include transfer molding and compression molding.

(Transfer molding method)
A method for manufacturing a molded product by transfer molding includes the steps of injecting a melt of the above-described resin molding material into a mold using a transfer molding apparatus, and curing the melt.

Transfer molding can be performed by appropriately using a known transfer molding apparatus. Specifically, first, a preheated resin molding material is placed in a heating chamber, which is also called a transfer chamber, and melted to obtain a melt. The melt is then injected into a mold with a plunger and held in place to allow the melt to harden. Thereby, a desired molding can be obtained.
Transfer molding is preferable in terms of the controllability of the dimensions of the molded product and the improvement of the degree of freedom in shape.

Various conditions in transfer molding can be arbitrarily set, but since the resin molding material of the present embodiment has excellent moldability in a molding process at a low temperature (about 100 to 150 ° C.), for example, preheating The temperature is 60 to 100°C, the heating temperature during melting is 100 to 150°C, the mold temperature is 100°C to 150°C, and the pressure when injecting the molten resin molding material into the mold is between 1 and 20 MPa. can be adjusted as appropriate.
Shrinkage of the molded product can be suppressed by not setting the mold temperature too high.

(Compression molding method)
A method for manufacturing a molded product by compression molding includes a step of compression molding the resin molding material.

Compression molding can be performed using a known compression molding apparatus as appropriate. Specifically, the resin molding material is placed in a concave portion of a fixed mold having a concave shape that opens upward. The resin molding material can be preheated. As a result, the molded article can be cured uniformly, and the molding pressure can be reduced.

Next, the convex mold is moved to the concave stationary mold from above, and the resin molding material is compressed in the cavity formed by the convex and concave portions. First, the resin molding material is sufficiently softened and fluidized at a low pressure, then the mold is closed and pressurized again to harden for a predetermined period of time.

Various conditions in compression molding can be set arbitrarily, but since the resin molding material of the present embodiment has excellent moldability in a molding process at a low temperature (about 100 to 150 ° C.), preheating, for example, can be performed. The temperature is 60 to 100°C, the heating temperature for melting is 100 to 150°C, the mold temperature is 100 to 150°C, the pressure when compressing the resin molding material in the mold is 1 to 20 MPa, and the curing time is 60 to 300. Seconds can be adjusted accordingly.
Shrinkage of the molded product can be suppressed by not setting the mold temperature too high.

Since the resin molding material of the present embodiment provides a magnetic material having high magnetic permeability, the molding obtained by curing the resin molding material seals the magnetic core in the inductor, the magnetic core, and the coil. It can be used for an exterior member to be used.

An overview of a structure (integrated inductor) provided with an exterior member made of a cured resin molding material of the present embodiment will be described with reference to FIG.
FIG. 1(a) shows an outline of the structure as viewed from above the structure 100. FIG. FIG. 1(b) shows a cross-sectional view taken along line AA' in FIG. 1(a).

The structure 100 of this embodiment can comprise a coil 10 and a magnetic core 20, as shown in FIG. The magnetic core 20 is filled inside the coil 10, which is an air-core coil. The coil 10 and the magnetic core 20 are sealed with an exterior member 30 (sealing member). The magnetic core 20 and the exterior member 30 can be made of the cured resin molding material of the present embodiment. Magnetic core 20 and exterior member 30 may be formed as a seamless integral member.

As a method for manufacturing the structure 100 of the present embodiment, for example, the coil 10 is placed in a mold, and the resin molding material of the present embodiment is molded by mold molding such as transfer molding. can be cured to integrally form the magnetic core 20 filled in the coil 10 and the exterior member 30 around them. At this time, the coil 10 may have a lead-out portion (not shown) that leads the end of the winding to the outside of the exterior member 30 .

The coil 10 is generally constructed by winding a metal wire with an insulating coating on its surface. The metal wire preferably has high conductivity, and copper and copper alloys can be suitably used. Also, as the insulating 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. Since the magnetic core 20 is composed of the transfer-molded product of the resin molding material of this embodiment, it can have a desired shape.

According to the cured product of the resin molding material of the present embodiment, it is possible to realize the magnetic core 20 and the exterior member 30 having excellent moldability and magnetic properties such as high magnetic permeability. is expected to have low magnetic loss. Moreover, since the exterior member 30 having excellent mechanical properties can be realized, the durability, reliability, and manufacturing stability of the structure 100 can be enhanced. Therefore, the structure 100 of this embodiment can be used as an inductor for a booster circuit or a large current.

Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above can be employed within the scope that does not impair the effects of the present invention.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these.

<Examples 1 to 4, Comparative Examples 1 to 8>
First, each component described in Table 1 was prepared at the described ratio, and while mixing the soft magnetic particles, other components were added and uniformly mixed to obtain a mixture.
The resulting mixture was then kneaded at 120° C. for 10 minutes. After kneading, the resulting kneaded product was cooled to room temperature to form a solid, pulverized and tableted. As described above, a tablet-shaped resin molding material was obtained.
The raw material components listed in Table 1 are shown below. Evaluation results of resin molding materials and molded articles in Table 1 are shown. The content (% by volume) of the soft magnetic particles shown in Table 1 is the content (that is, filling rate) when the resin molding material containing the soft magnetic particles is taken as 100% by volume.

(Soft magnetic particles (iron-based particles))
・Magnetic powder 1: Amorphous magnetic powder (manufactured by Epson Atmix, KUAMET6B2 053C03, median diameter _D50 : 23 µm, Fe 87% by mass)
・Magnetic powder 2: Magnetic powder (manufactured by BASF, CIP-HQ, median diameter _D50 : 1.8 μm, Fe97% by mass)

(coupling agent)
Coupling agent 1: CF-4083 (phenylaminopropyltrimethoxysilane, Dow Corning Toray Co., Ltd.)

(Epoxy resin)
・ Epoxy resin 1: biphenyl aralkyl type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., NC-3000L, solid at 23 ° C., containing structural unit represented by the above general formula (BP1))
・ Epoxy resin 2: o-cresol novolac epoxy resin (CNE195LL, manufactured by Changchun Jinjin Resin Co., Ltd.)

(curing agent)
- Phenolic curing agent 1: Biphenylene skeleton-containing phenol aralkyl type resin (manufactured by Meiwa Kasei Co., Ltd., MEH-7851SS)
・ Phenol curing agent 2: Phenol novolac resin (manufactured by Sumitomo Bakelite Co., Ltd., PR-HF-3)

(catalyst)
- Imidazole catalyst 1: 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine (manufactured by Shikoku Kasei Co., Ltd., C11Z-A)
- Imidazole catalyst 2: 2-phenyl-1H-imidazole 4,5-dimethanol (manufactured by Shikoku Kasei Co., Ltd., 2PHZ-PW)
- Imidazole catalyst 3: 2-phenyl-4-methyl-5-hydroxymethylimidazole (manufactured by Shikoku Kasei Co., Ltd., 2P4MHZ-PW)

(Release agent)
・Wax: Carnauba wax (TOWAX-132 manufactured by Toa Kasei Co., Ltd.)

(dispersant)
・ Dispersant: stearic acid (manufactured by NOF Corporation, SR-Sakura)

<Evaluation>
(higher viscosity)
Using a Koka-style viscosity measuring device (Koka-style flow tester, Shimadzu Corporation, CFT-100EX), the measurement temperature is 130 ° C., the load is 40 kgf, and the nozzle dimensions are: diameter 1.0 mm x length 10 mm. The Koka viscosity (Pa·s) of the molding material was measured.

(Relative magnetic permeability)
Molding material 1 was 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, a magnetization curve (BH curve) was obtained for the molded product 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 was obtained, and the relative magnetic permeability was calculated by dividing the obtained maximum magnetic permeability by the magnetic permeability in vacuum.

(Transfer moldability)
Using a low-pressure transfer molding machine ("KTS-30" manufactured by Kotaki Seiki Co., Ltd.), injection molding was performed at a mold temperature of 130 ° C., an injection pressure of 9.8 MPa, and a curing time of 300 seconds. Four molded products of 10 mm×80 mm×4 mmt were produced. Then, transfer moldability was evaluated according to the following criteria.
◯ (Good): No unfilled portion was observed in the obtained molding.
x (defective): Unfilled portions were observed even in one of the obtained moldings.

(Compression moldability (compression moldability))
Using a compression molding machine (manufactured by TOWA Co., Ltd., PMC1040), the resin molding material is molded at a mold temperature of 130 ° C., a molding pressure of 2 MPa, and a curing time of 300 seconds. A compact (magnetic member) having a length of 54 mm, a width of 217 mm, and a thickness of 0.5 mm was formed. After cooling, the cured product (molded product) in the mold was taken out and its appearance was observed. The compression moldability was evaluated according to the following criteria.
◯ (Good): No unfilled portion was observed in the obtained molding.
x (bad): Unfilled portions were observed in the obtained molding.

[Bending strength and bending elastic modulus]
The resin molding material was injected into a mold using a low-pressure transfer molding machine ("KTS-30" manufactured by Kotaki Seiki Co., Ltd.) under the conditions of a mold temperature of 130 ° C., an injection pressure of 10.0 MPa, and a curing time of 120 seconds. . As a result, 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 130° C. for 4 hours. This produced a test piece for evaluation of mechanical strength. Then, the flexural strength (MPa) and flexural modulus (MPa) of the test piece at room temperature (25° C.) were measured according to JIS K 6911.

As shown in Table 1, the resin molding materials of Examples have low high viscosity (melt viscosity) and are excellent in fillability into molds and the like in the low-temperature molding process of transfer molding or compression molding. It was excellent in magnetic properties as well as excellent in properties. Thus, by using the imidazole catalyst (C), excellent magnetic properties and moldability, which are in a trade-off relationship, are well balanced. Furthermore, the resin molding materials of Examples could provide cured products having excellent mechanical strength such as bending strength.

100 structure 10 coil 20 magnetic core 30 exterior member

Claims (14)

A resin molding material used for transfer molding or compression molding,
(A) an epoxy resin;
(B) a curing agent;
(C) an imidazole catalyst containing a long-chain hydrocarbon group having 3 to 20 carbon atoms;
(D) soft magnetic particles;
Resin molding material, including. 2. The resin molding material according to claim 1, wherein the imidazole catalyst (C) contains a terminal saturated or unsaturated long-chain aliphatic group having 3 to 20 carbon atoms. 3. The resin molding material according to claim 1, wherein the imidazole catalyst (C) contains a compound represented by the following general formula (1).

(In general formula (1), R represents a saturated or unsaturated long-chain aliphatic group having 3 to 20 carbon atoms, Q represents a cyano group or an optionally substituted triazinyl group, n represents 1 to 5 indicates an integer of 4. The resin molding material according to claim 1, wherein the imidazole catalyst (C) contains a compound having a triazine skeleton in its structure. The resin molding material according to any one of claims 1 to 4, further comprising a dispersant (E) containing a linear fatty acid having 8 to 20 carbon atoms. The fatty acids contained in the dispersant (E) include caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, pentadecyl acid, palmitic acid, palmitoleic acid, margaric acid, stearic acid, oleic acid, paxenoic acid, and linoleic acid. 6. The resin molding material according to claim 5, comprising at least one selected from , eleostearic acid, and arachidic acid. The resin molding material according to any one of claims 1 to 6, which contains 85% by mass or more of the soft magnetic particles (D) in 100% by mass of the resin molding material. The resin molding material according to any one of claims 1 to 7, wherein the soft magnetic particles (D) contain iron-based particles. The resin molding material according to any one of claims 1 to 8, which is a low temperature curable material at 100°C to 150°C. Using a Koka-type viscosity measuring device, the Koka-type viscosity measured under conditions of a measurement temperature of 130 ° C. and a load of 40 kgf is 100 Pa s or more and 1000 Pa s or less, according to any one of claims 1 to 9. Resin molding material. The resin molding material according to any one of claims 1 to 10, which is in the form of tablets or granules at 23°C. A molded article obtained by curing the resin molding material according to any one of claims 1 to 11. A step of injecting the melt of the resin molding material according to any one of claims 1 to 11 into a mold using a transfer molding device;
curing the melt at 100° C. to 150° C.;
A method of manufacturing a molded article, comprising: A method for producing a molded product, comprising a step of compression molding the resin molding material according to any one of claims 1 to 11 at 100°C to 150°C.

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