Tablet-shaped epoxy resin molding material, columnar tablet, and method for manufacturing columnar tablet

Abstract

A tablet-shaped epoxy resin molding material according to the present invention contains an epoxy resin and a fibrous or acicular filler. The cross-sectional area is 3 cm2 to 100 cm2. The compression ratio calculated from [(M / G) / V]×100, where G is the specific gravity, M (g) is the mass, and V (cm3) is the volume, as measured in accordance with JIS 6911:2006, in the tablet-shaped epoxy resin molding material, satisfies 70-95%.

Description

[Technical Field]

[0001] The present invention relates to a tablet-shaped epoxy resin molding material, a columnar tablet, and a method for manufacturing a columnar tablet. [Background technology]

[0002] Various developments have been made regarding the molding methods for tablet-shaped epoxy resin materials. As an example of this type of technology, the technology described in Patent Document 1 is known. Patent Document 1 describes a method for transfer molding a tablet-shaped epoxy resin composition containing inorganic fillers such as quartz glass powder, talc, silica powder, alumina powder, and calcium carbonate for encapsulating semiconductor devices (Claim 1, paragraphs 0005, 0030, etc. of Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-208805 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, as a result of the inventors' investigation, it was found that there is room for improvement in terms of breakability during transport and fracture toughness of the tablet-shaped epoxy resin molding material described in Patent Document 1. [Means for solving the problem]

[0005] Further investigation by the inventors revealed that by lowering the compressibility of the tablet-shaped epoxy resin molding material to an appropriate value, it is possible to mold a molded article with excellent resistance to breakage during transport and fracture toughness, thus completing the present invention.

[0006] According to one aspect of the present invention, the following tablet-shaped epoxy resin molding material, columnar tablets, and a method for manufacturing columnar tablets are provided.

[0007] 1. A tablet-shaped epoxy resin molding material, Epoxy resin and Including fibrous or needle-shaped fillers, The cross-sectional area is 3 cm 2 More than 100cm 2 The following: In the tablet-shaped epoxy resin molding material, the specific gravity is G, the mass is M (g), and the volume is V (cm³), as measured in accordance with JIS 6911:2006. 3 A tablet-shaped epoxy resin molding material in which, when given [(M / G) / V] × 100, the compressibility ratio is 70% or more and 95% or less. 2. The tablet-shaped epoxy resin molding material described in 1. A tablet-shaped epoxy resin molding material in which the volume-average fiber length of the fibrous or needle-shaped filler, as measured by the following procedure A, is 5 μm or more and 500 μm or less. (Procedure A) After dissolving the tablet-shaped epoxy resin molding material in acetone to remove the resin components, the insoluble matter is dispersed on a glass plate, and the filler in the insoluble matter is photographed using an optical microscope. The fiber length is then measured using an image analysis device. The average fiber length, based on the volume of the 100 fillers with the longest fiber length, is defined as the volume-average fiber length. 3. A tablet-shaped epoxy resin molding material as described in 1. or 2., When L is the volume-average fiber length of the fibrous or needle-shaped filler measured in procedure A below, and D is the number-average fiber diameter of the fibrous or needle-shaped filler measured in procedure B below, A tablet-shaped epoxy resin molding material having an L / D ratio of 3 to 100. (Procedure A) After dissolving the tablet-shaped epoxy resin molding material in acetone to remove the resin components, the insoluble matter is dispersed on a glass plate, and the filler in the insoluble matter is photographed using an optical microscope. The fiber length is then measured using an image analysis device. The average fiber length, based on the volume of the 100 fillers with the longest fiber length, is defined as the volume-average fiber length. (Procedure B) Using a scanning electron microscope, 100 cross-sections of fibrous filler are measured from the cross-section of the tablet-shaped epoxy resin molded material, and the average of the minimum diameters of each fiber cross-section is determined as the number-average fiber diameter. 4. A tablet-shaped epoxy resin molding material described in any one of 1. to 3., A tablet-shaped epoxy resin molding material wherein the fibrous or needle-shaped filler comprises one or more selected from the group consisting of wollastonite fibers, glass fibers, metal fibers, carbon fibers, fibrous aluminum oxide, aramid fibers, silicon carbide whiskers, silicon nitride whiskers, and potassium titanate whiskers. 5. A tablet-shaped epoxy resin molding material described in any one of 1. to 4., A tablet-shaped epoxy resin molding material having a spiral flow of 20 cm or more, as measured according to the following procedure. (procedure) Using a low-pressure transfer molding machine, the tablet-shaped epoxy resin molding material is injected into a spiral flow measurement mold conforming to EMMI-1-66 under the conditions of a mold temperature of 175°C, an injection pressure of 6.9 MPa, and a curing time of 120 seconds, and the flow length (cm) is measured. 6. A tablet-shaped epoxy resin molding material described in any one of items 1 to 5, A tablet-shaped epoxy resin molding material in which the content of the fibrous or needle-shaped filler is 5% by mass or more and 80% by mass or less of the tablet-shaped epoxy resin molding material by 100% by mass. 7. A tablet-shaped epoxy resin molding material described in any one of 1. to 6., A tablet-shaped epoxy resin molding material wherein the epoxy resin comprises a cresol novolac type epoxy resin and / or a bisphenol A type epoxy resin. 8. A tablet-shaped epoxy resin molding material described in any one of 1. to 7., A tablet-shaped epoxy resin molding material comprising one or more curing catalysts selected from the group consisting of amine-based catalysts and phosphorus-based catalysts. 9. A tablet-shaped epoxy resin molding material described in any one of items 1 to 8, 5cm 3 More than 1500cm 3 A tablet-shaped epoxy resin molding material having the following volume. 10. A tablet-shaped epoxy resin molding material described in any one of items 1 to 9, A tablet-shaped epoxy resin molding material used for magnet fixing, electronic control unit sealing, coil sealing, or stator core sealing. 11. A columnar tablet formed from a tablet-shaped epoxy resin molding material described in any one of items 1 to 10. 12. A step of obtaining an epoxy resin molding material by melt-kneading an epoxy resin composition containing epoxy resin and fibrous or needle-shaped filler, The process includes obtaining a columnar tablet using the obtained epoxy resin molding material, The cross-sectional area of ​​the columnar tablet is 3 cm 2 More than 100cm 2 The following: In the aforementioned columnar tablet, the specific gravity measured in accordance with JIS 6911:2006 is G, the mass is M (g), and the volume is V (cm³). 3 When this is the case, the compression ratio calculated from [(M / G) / V] × 100 is between 70% and 95%. A method for manufacturing columnar tablets. [Effects of the Invention]

[0008] According to the present invention, there are provided a tablet-shaped epoxy resin molding material, a columnar tablet, and a method for producing the columnar tablet, which can form a molded body excellent in breakage resistance and fracture toughness during transportation.

Brief Description of the Drawings

[0009] [Figure 1] It is a cross-sectional view for explaining the outline of a tensile-compression testing machine.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and the description will be omitted as appropriate. Further, the drawings are schematic views and do not match the actual dimensional ratios.

[0011] The outline of the tablet-shaped epoxy resin molding material of the present embodiment will be described.

[0012] The tablet-shaped epoxy resin molding material of the present embodiment includes an epoxy resin and a fibrous or needle-like filler. The cross-sectional area is 3 cm 2 or more and 100 cm 2 or less, When the specific gravity measured in accordance with JIS 6911:2006 is G, the mass is M (g), and the volume is V (cm 3 ), it is configured to satisfy a compression ratio calculated from [(M / G) / V]×100 of 70% or more and 95% or less.

[0013] According to the findings of the present inventor, it has been found that by appropriately lowering the compression ratio of the tablet-shaped epoxy resin molding material, a molded body excellent in fracture toughness can be formed. Although the detailed mechanism is not clear, the fact that the compression ratio of the tablet is moderately low means that the tablet is formed under mild conditions. During the molding process of the tablet under mild conditions, it is possible to suppress a decrease in the fiber length of the fibrous or needle-like filler. Therefore, it is presumed that a decrease in the fracture toughness of the molded body can be prevented.

[0014] The upper limit of the above compression ratio is 95% or less, preferably 94% or less, and more preferably 93% or less. This makes it possible to form a molded article with excellent fracture toughness. In addition, it is possible to improve mechanical strength such as the flexural modulus. On the other hand, the lower limit of the compression ratio is, for example, 70% or more, preferably 75% or more, and more preferably 80% or more. This helps to suppress the decrease in the breakability of the molded article during transportation. Transportation methods include air transport, land transport, and sea transport.

[0015] In this embodiment, the compression ratio can be controlled by appropriately selecting, for example, the types and amounts of each component contained in the epoxy resin molding material, the method of preparing the epoxy resin molding material, etc. Among these, for example, appropriately controlling the molding pressure and compression time during molding as manufacturing conditions, and increasing the fiber length of the fiber filler are examples of factors that can bring the compression ratio into a desired numerical range.

[0016] Such epoxy resin molding materials can be used for magnet fixing, electronic control unit (ECU) encapsulation, coil encapsulation, or stator core encapsulation, among others. Specifically, tablet-shaped epoxy resin molding materials can be used for magnet fixing, electronic control unit (ECU) encapsulation, coil encapsulation, or stator core encapsulation by known molding methods. In each of these applications, the mechanical properties of the molded body, such as its flexural modulus, can be improved. Furthermore, in rotor cores with a skewed structure, the occurrence of gaps when magnet fixing material is filled in can be suppressed.

[0017] The columnar tablet of this embodiment is a columnar molded body obtained by molding the epoxy resin molding material described above.

[0018] A method for producing tablet-shaped epoxy resin molding material may include, for example, a step of melt-kneading an epoxy resin composition containing at least an epoxy resin and a fibrous or needle-shaped filler to obtain an epoxy resin molding material, and a step of obtaining tablets using the obtained epoxy resin molding material.

[0019] A known method can be used to obtain the tablets, but for example, a tablet molding machine may be used to compress a granular epoxy resin composition into tablets. The method is not limited to this molding method, and a method may also be used in which molten epoxy resin molding material is continuously extruded from the opening at the tip of an extruder while the epoxy resin molding material is cut to obtain tablets.

[0020] Powdered epoxy resin compositions include powder and / or granules. For example, relatively coarse particles (granules) can be crushed and / or classified to obtain relatively fine particles (powder). The particle shape of the epoxy resin composition is not particularly limited and may be spherical, polygonal, irregularly shaped, etc. These may be used individually or in combination of two or more types.

[0021] The volume of a tablet-shaped epoxy resin molding material (tablet) is, for example, 5 cm³. 3 More than 1500cm 3 Preferably 10 cm 3 More than 1000cm 3 The following applies: The cross-sectional area of ​​a columnar tablet is, for example, 3 cm². 2 More than 100cm 2 Preferably 10 cm 2 95cm or more 2 The following applies: The length of the columnar tablet is, for example, 10 mm to 300 mm, and preferably 20 mm to 200 mm.

[0022] Using a tablet-shaped epoxy resin molding material and employing known molding methods such as transfer molding, any of the fixing or sealing structures selected from the group consisting of magnet fixing structures, electronic control unit sealing structures, coil sealing structures, and stator core sealing structures, as exemplified below, can be manufactured.

[0023] Regarding the above-mentioned fixed or sealed structures, for example, as a rotor core to which magnets are fixed, see International Publication WO2012 / 029278, for example; as an in-vehicle electronic control unit, see International Publication WO2016 / 139985, for example; and as a stator core, see Japanese Patent Application Publication 2020-094092, for example.

[0024] The case in which epoxy resin molding material is used for the above magnet fixing structure will be explained. The rotor core comprises multiple holes and permanent magnets inserted into each of the holes. The permanent magnets can be fixed to the rotor core by filling the space between the holes and the permanent magnets with epoxy resin molding material.

[0025] This section describes the case where epoxy resin molding material is used for the encapsulation structure of an automotive electronic control unit. An in-vehicle electronic control unit includes a circuit board on which electronic components are mounted. In an in-vehicle electronic control unit, at least a portion of the circuit board, along with the electronic components, can be sealed with an epoxy resin molding material.

[0026] This section describes the case where epoxy resin molding material is used for the coil encapsulation structure. A coil, consisting of a winding made of copper wire or similar material, is used in motors, transformers, and other applications. This coil is then molded (sealed) with epoxy resin molding material for insulation.

[0027] This section describes the case where epoxy resin molding material is used for the stator core sealing structure. The stator core comprises multiple teeth and coils (windings) wound around each of the multiple teeth. By sealing the coil wound around the teeth with epoxy resin molding material, the coil and the stator core can be insulated. Furthermore, if the stator core has a housing portion in the teeth, the coil wound around the teeth can be housed in the housing portion, and the space between them can be filled with epoxy resin molding material to insulate the coil and the stator core. As another example of manufacturing, an insulating layer can be formed on the surface of the stator core using epoxy resin molding material. Subsequently, a coil is inserted into the teeth section, and this coil is sealed using epoxy resin molding material. The windings that can be used for the above-mentioned coils and stator cores may be made of round wire or flat rectangular wire.

[0028] The process for manufacturing a fixed structure or a sealed structure may be carried out, for example, using a tablet-shaped epoxy resin molding material, at a temperature of 120°C to 200°C and a pressure of 3 MPa to 15 MPa, preferably at a temperature of 140°C to 180°C and a pressure of 5 to 12 MPa.

[0029] The lower limit of the spiral flow of the epoxy resin molding material is, for example, 30 cm or more, preferably 50 cm or more. On the other hand, the upper limit of the spiral flow of the epoxy resin molding material is, for example, 250 cm or less, preferably 200 cm or less. Spiral flow can be measured following these steps: Using a low-pressure transfer molding machine, epoxy resin molding material is injected into a spiral flow measurement mold conforming to EMMI-1-66 under the conditions of mold temperature 175°C, injection pressure 6.9 MPa, and curing time 120 seconds, and the flow length (cm) is measured.

[0030] The method for manufacturing tablets using the epoxy resin molding material of this embodiment is not limited to compression molding, but may also be used, such as extrusion molding, transfer molding, or injection molding.

[0031] The components of the epoxy resin molding material of this embodiment will be described in detail below.

[0032] [Epoxy resin] Epoxy resin molding materials contain epoxy resin. Examples of epoxy resins include novolac-type phenolic resins such as phenol novolac resin, cresol novolac resin, and bisphenol A novolac resin; phenolic resins such as resol-type phenolic resin; novolac-type epoxy resins such as phenol novolac-type epoxy resin and cresol novolac-type epoxy resin; bisphenol-type epoxy resins such as bisphenol A-type epoxy resin and bisphenol F-type epoxy resin; aromatic glycidylamine-type epoxy resins such as N,N-diglycidylaniline, N,N-diglycidyltoluidine, diaminodiphenylmethane-type glycidylamine, and aminophenol-type glycidylamine; hydroquinone-type epoxy resins; biphenyl-type epoxy resins; and stilbene. Examples of epoxy resins include aralkyl epoxy resins such as triphenolmethane-type epoxy resins, triphenolpropane-type epoxy resins, alkyl-modified triphenolmethane-type epoxy resins, triazine core-containing epoxy resins, dicyclopentadiene-modified phenol-type epoxy resins, naphthol-type epoxy resins, naphthalene-type epoxy resins, phenol aralkyl-type epoxy resins having a phenylene and / or biphenylene skeleton, and naphthol aralkyl-type epoxy resins having a phenylene and / or biphenylene skeleton, as well as aliphatic epoxy resins such as vinylcyclohexene dioxide, dicyclopentadiene oxide, and alicyclic diepoxy adipade. These may be used individually or in combination of two or more types. Among these, the epoxy resin preferably includes a cresol novolac type epoxy resin and / or a bisphenol A type epoxy resin.

[0033] The epoxy resin content is preferably 5% to 40% by mass, and more preferably 10% to 20% by mass, relative to the total epoxy resin molding material.

[0034] [Hardening agent] The epoxy resin molding material may contain a curing agent for curing the epoxy resin. As a curing agent, for example, a phenolic resin-based curing agent is preferably used. Examples of phenolic resin-based curing agents include novolac-type resins such as phenol novolac resin, cresol novolac resin, and naphthol novolac resin; polyfunctional phenolic resins such as triphenolmethane-type phenolic resin; modified phenolic resins such as terpene-modified phenolic resin and dicyclopentadiene-modified phenolic resin; aralkyl-type resins such as phenol aralkyl resin having a phenylene skeleton and / or biphenylene skeleton, and naphthol aralkyl resin having a phenylene and / or biphenylene skeleton; and bisphenol compounds such as bisphenol A and bisphenol F. These may be used individually or in combination of two or more. Such phenolic resin-based curing agents provide a good balance of flame resistance, moisture resistance, electrical properties, curability, and storage stability.

[0035] Furthermore, examples of curing agents that can be used in combination include polyaddition-type curing agents and condensation-type curing agents.

[0036] Examples of polyaddition-type curing agents include aliphatic polyamines such as diethylenetriamine (DETA), triethylenetetramine (TETA), and metaxylenediamine (MXDA), aromatic polyamines such as diaminodiphenylmethane (DDM), m-phenylenediamine (MPDA), and diaminodiphenylsulfone (DDS), as well as polyamine compounds including dicyandiamide (DICY) and organic acid dihydrazides; alicyclic acid anhydrides such as hexahydrophthalic anhydride (HHPA) and methyltetrahydrophthalic anhydride (MTHPA), and acid anhydrides including trimellitic anhydride (TMA), pyromellitic anhydride (PMDA), and benzophenonetetracarboxylic acid (BTDA); polyphenol compounds such as novolac-type phenol resins and phenol polymers; polymercaptan compounds such as polysulfides, thioesters, and thioethers; isocyanate compounds such as isocyanate prepolymers and blocked isocyanates; and organic acids such as carboxylic acid-containing polyester resins.

[0037] Examples of condensation-type curing agents include urea resins such as resol resins and methylol group-containing urea resins; and melamine resins such as methylol group-containing melamine resins.

[0038] Furthermore, it is preferable that the phenolic resin used as a curing agent and the epoxy resin are blended such that the equivalent ratio (EP) / (OH) of the number of epoxy groups (EP) in the epoxy resin molding material to the number of phenolic hydroxyl groups (OH) in the total phenolic resin is between 0.8 and 1.3. When the equivalent ratio is within the above range, sufficient curing properties can be obtained when molding the resulting epoxy resin molding material. However, if a resin other than phenolic resin that can react with epoxy resin is used in combination, the equivalent ratio may be adjusted as appropriate.

[0039] [Inorganic filler] (Fibrous or needle-shaped fillers) The epoxy resin molding material contains fibrous or needle-shaped fillers as inorganic fillers.

[0040] The lower limit of the volume-average fiber length of the fibrous or needle-shaped filler is, for example, 5 μm or more, preferably 10 μm or more, more preferably 30 μm or more, and even more preferably 50 μm or more. This can improve the strength of the material. On the other hand, the upper limit of the volume-average fiber length of the fibrous or needle-shaped filler is, for example, 500 μm or less, preferably 450 μm or less, and more preferably 400 μm or less. This improves the moldability of the material.

[0041] When L is the volume-average fiber length of a fibrous or needle-shaped filler and D is the number-average fiber diameter of a fibrous or needle-shaped filler, the aspect ratio is defined as L / D. The lower limit of the L / D ratio for fibrous or needle-shaped fillers is, for example, 3 or more, preferably 10 or more, and more preferably 15 or more. This allows for further improvement of the flexural modulus and also improves toughness. On the other hand, the upper limit of the L / D ratio for fibrous or needle-shaped fillers is, for example, 100 or less, preferably 70 or less, and more preferably 50 or less. This improves the moldability of the material.

[0042] (Measurement procedure for volume-average fiber length A) After dissolving the epoxy resin molding material in acetone to remove the resin components, the insoluble matter is dispersed on a glass plate, and the fillers in the insoluble matter are photographed using an optical microscope. The fiber length is then measured using an image analysis device. The average fiber length, based on the volume of the 100 fillers with the longest fiber length, is defined as the volume-average fiber length.

[0043] (Measurement procedure for number-average fiber diameter B) Using a scanning electron microscope, the cross-sections of 100 fibrous fillers were measured from the cross-section of the epoxy resin molding material, and the average of the minimum diameters of each fiber cross-section was determined as the number-average fiber diameter.

[0044] The fibrous or needle-shaped filler may include one or more selected from the group consisting of, for example, wollastonite fibers, glass fibers, metal fibers, carbon fibers, fibrous aluminum oxide, aramid fibers, silicon carbide whiskers, silicon nitride whiskers, and potassium titanate whiskers. Among these, it is preferable to include at least one of wollastonite fibers and glass fibers, and more preferable to include wollastonite fibers.

[0045] The lower limit of the fibrous or needle-shaped filler content is, for example, 5% by mass or more, preferably 10% by mass or more, and more preferably 30% by mass or more, per 100% by mass of the epoxy resin composition. This can further improve the flexural modulus and also improve toughness. On the other hand, the upper limit of the content of fibrous or needle-shaped fillers is not particularly limited, but may be 80% by mass or less, preferably 75% by mass or less, in 100% by mass of the epoxy resin composition.

[0046] Furthermore, the lower limit of the content of fibrous or needle-shaped fillers in all inorganic fillers is, for example, 30% by mass or more, preferably 40% by mass or more, and more preferably 50% by mass or more. This allows for further improvement of the flexural modulus and also improves toughness. On the other hand, there is no particular upper limit to the content of fibrous or needle-shaped fillers in all inorganic fillers, but it may be 100% by mass or less.

[0047] (Other inorganic fillers besides fibrous or needle-shaped fillers) The epoxy resin molding material may contain inorganic fillers other than fibrous or needle-shaped fillers. Other inorganic fillers are not particularly limited as long as they have shapes such as spherical, polygonal, or irregular. Specifically, other inorganic fillers with an aspect ratio of 2 or less are preferred, and spherical ones are more preferred.

[0048] Other inorganic fillers include, for example, silica, alumina, kaolin, talc, clay, mica, rock wool, glass powder, glass flakes, glass beads, silicon carbide, silicon nitride, aluminum nitride, carbon black, graphite, titanium dioxide, calcium carbonate, calcium sulfate, barium carbonate, magnesium carbonate, magnesium sulfate, barium sulfate, etc. These may be used individually or in combination of two or more. The silica used includes fused silica such as molten crushed silica and molten spherical silica, as well as crystalline silica.

[0049] Average particle size D of inorganic fillers 50 The average particle size of the inorganic filler is preferably 0.01 μm or more and 75 μm or less, and more preferably 0.05 μm or more and 50 μm or less. By keeping the average particle size of the inorganic filler within the above range, the packing performance in the mold is improved. Furthermore, by setting the upper limit of the average particle size of the inorganic filler to 75 μm or less, the packing performance is further improved. Average particle size D 50 The volume-reduced average particle size was determined using a laser diffraction type measuring device, RODOS SR model (SYMPATEC HEROS & RODOS).

[0050] The inorganic filler content is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 65% ​​by mass or more, and particularly preferably 75% by mass or more, relative to the total epoxy resin molding material. On the other hand, the inorganic filler content is preferably 93% by mass or less, more preferably 91% by mass or less, and even more preferably 90% by mass or less, relative to the total epoxy resin molding material.

[0051] Furthermore, when using inorganic fillers in combination with metal hydroxides such as aluminum hydroxide and magnesium hydroxide, or inorganic flame retardants such as zinc borate, zinc molybdate, and antimony trioxide, it is desirable that the total amount of these inorganic flame retardants and the inorganic fillers be within the range of the inorganic filler content.

[0052] [Curing catalyst] The epoxy resin molding material may contain a curing catalyst if necessary. As the curing catalyst, it is preferable to use one or more selected from the group consisting of amine-based catalysts and phosphorus-based catalysts.

[0053] As an amine catalyst, it is preferable to use imidazoles, for example. Examples of imidazoles include imidazole, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 2-phenyl-4,5-dihydroxyimidazole, 2-phenyl-4,5-dihydroxydimethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole. The following compounds may be included: imidazole compounds, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4-methylimidazolyl(1')]-ethyl-s-triazine, isocyanuric acid adducts of 2,4-diamino-6-[2'-methylimidazolyl(1')]-ethyl-s-triazine, isocyanuric acid adducts of 2-phenylimidazole, isocyanuric acid adducts of 2-methylimidazole, hexamethylenetetramine, etc.

[0054] When the curing catalyst includes an amine-based catalyst, the lower limit of the amine-based catalyst content is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, and particularly preferably 0.05% by mass or more, relative to the total epoxy resin molding material. Furthermore, the upper limit of the amine-based catalyst content is preferably 2.0% by mass or less, more preferably 1.5% by mass or less, and particularly preferably 1.0% by mass or less, relative to the total epoxy resin molding material.

[0055] Examples of phosphorus-based catalysts include phosphorus-containing compounds such as organophosphines, tetrasubstituted phosphonium compounds, phosphobetaine compounds, adducts of phosphine compounds and quinone compounds, and adducts of phosphonium compounds and silane compounds.

[0056] Examples of organic phosphines that can be used in epoxy resin molding materials include primary phosphines such as ethylphosphine and phenylphosphine; secondary phosphines such as dimethylphosphine and diphenylphosphine; and tertiary phosphines such as trimethylphosphine, triethylphosphine, tributylphosphine, and triphenylphosphine.

[0057] Examples of tetrasubstituted phosphonium compounds that can be used in epoxy resin molding materials include compounds represented by the following general formula (4).

[0058] [ka] (In the above general formula (4), P represents a phosphorus atom. R 4 , R 5 , R 6 and R 7represents an aromatic group or alkyl group. A represents an anion of an aromatic organic acid having at least one functional group selected from a hydroxyl group, carboxyl group, or thiol group on its aromatic ring. AH represents an aromatic organic acid having at least one functional group selected from a hydroxyl group, carboxyl group, or thiol group on its aromatic ring. x and y are numbers from 1 to 3, z is a number from 0 to 3, and x = y.

[0059] Compounds represented by general formula (4) can be obtained, for example, as follows, but are not limited to these methods. First, a tetrasubstituted phosphonium halide, an aromatic organic acid, and a base are mixed homogeneously in an organic solvent to generate aromatic organic acid anions in the solution system. Then, water is added to precipitate the compound represented by general formula (4). In the compound represented by general formula (4), R bonded to the phosphorus atom 4 , R 5 , R 6 and R 7 Preferably, AH is a phenyl group, AH is a compound having a hydroxyl group in the aromatic ring, i.e., a phenol, and A is the anion of the phenol. Examples of the phenols include monocyclic phenols such as phenol, cresol, resorcinol, and catechol; condensed polycyclic phenols such as naphthol, dihydroxynaphthalene, and anthraquinol; bisphenols such as bisphenol A, bisphenol F, and bisphenol S; and polycyclic phenols such as phenylphenol and biphenol.

[0060] Examples of phosphobetaine compounds used as curing catalysts include compounds represented by the following general formula (5).

[0061] [ka] (In the above general formula (5), R 8 R is an alkyl group having 1 to 3 carbon atoms. 9 (where f represents a hydroxyl group, and g represents a number from 0 to 5, and g represents a number from 0 to 3.)

[0062] Compounds represented by general formula (5) can be obtained, for example, as follows: First, a triaromatically substituted phosphine, which is a tertiary phosphine, is brought into contact with a diazonium salt, and the diazonium group of the triaromatically substituted phosphine is substituted for the diazonium group of the diazonium salt. However, the method is not limited to this.

[0063] Examples of adducts of phosphine compounds and quinone compounds used as curing catalysts include compounds represented by the following general formula (6).

[0064] [ka] (In the above general formula (6), P represents a phosphorus atom. R 10 , R 11 and R 12 R represents an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms, and these may be the same or different. 13 , R 14 and R 15 R represents a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms, and they may be the same or different from each other. 14 and R 15 (They may be joined together to form a ring structure.)

[0065] The phosphine compounds used in the adducts of phosphine compounds and quinone compounds are preferably those with an unsubstituted or substituted aromatic ring, such as triphenylphosphine, tris(alkylphenyl)phosphine, tris(alkoxyphenyl)phosphine, trinaphthylphosphine, and tris(benzyl)phosphine. Examples of substituents such as alkyl groups and alkoxyl groups have 1 to 6 carbon atoms. Triphenylphosphine is preferred from the viewpoint of availability.

[0066] Furthermore, examples of quinone compounds used in adducts of phosphine compounds and quinone compounds include benzoquinones and anthraquinones, with p-benzoquinone being preferred in terms of storage stability.

[0067] A method for producing adducts of phosphine compounds and quinone compounds involves contacting and mixing the organic tertiary phosphine and benzoquinone compounds in a solvent in which both can be dissolved. Suitable solvents include ketones such as acetone and methyl ethyl ketone, which have low solubility in the adduct. However, the method is not limited to these.

[0068] In the compound represented by general formula (6), R bonded to the phosphorus atom 10 , R 11 and R 12 is a phenyl group and R 13 , R 14 and R 15 Compounds in which the atom is a hydrogen atom, i.e., compounds to which 1,4-benzoquinone and triphenylphosphine are added, are preferred in that they reduce the thermal modulus of the cured epoxy resin molding material.

[0069] Examples of adducts of phosphonium compounds and silane compounds used as curing catalysts include compounds represented by the following general formula (7).

[0070] [ka] (In the above general formula (7), P represents a phosphorus atom and Si represents a silicon atom. 16 , R 17 , R 18 and R 19 Each of these represents an organic group having an aromatic ring or a heterocycle, or an aliphatic group, and they may be the same or different from each other. 20 is, base Y 2 and Y 3 It is an organic group that bonds with R. 21 is, base Y 4 and Y 5It is an organic group that bonds with Y. 2 and Y 3 This represents a group formed when a proton-donating group releases a proton, and the Y group within the same molecule 2 and Y 3 It combines with silicon atoms to form a chelate structure. 4 and Y 5 Y represents a group formed when a proton-donating group releases a proton, and Y is a group within the same molecule. 4 and Y 5 It combines with silicon atoms to form a chelate structure. 20 , and R 21 They may be the same or different from each other, Y 2 , Y 3 , Y 4 and Y 5 Z may be identical or different from each other. 1 (This refers to an organic group having an aromatic ring or heterocycle, or an aliphatic group.)

[0071] In general formula (7), R 16 , R 17 , R 18 and R 19 Examples of such groups include phenyl, methylphenyl, methoxyphenyl, hydroxyphenyl, naphthyl, hydroxynaphthyl, benzyl, methyl, ethyl, n-butyl, n-octyl, and cyclohexyl groups. Among these, aromatic groups having substituents such as alkyl groups, alkoxy groups, or hydroxyl groups, such as phenyl, methylphenyl, methoxyphenyl, hydroxyphenyl, and hydroxynaphthyl groups, or unsubstituted aromatic groups are more preferred.

[0072] Furthermore, in general formula (7), R 20 Y 2 and Y 3 It is an organic group that bonds with R. 21 is, base Y 4 and Y 5 It is an organic group that bonds with Y. 2 and Y 3is a group formed by a proton-donating group releasing a proton, and the group Y within the same molecule 2 and Y 3 are bonded to a silicon atom to form a chelate structure. Similarly, Y 4 and Y 5 is a group formed by a proton-donating group releasing a proton, and the group Y within the same molecule 4 and Y 5 are bonded to a silicon atom to form a chelate structure. The groups R 20 and R 21 may be the same as or different from each other, and the groups Y 2 , Y 3 , Y 4 and Y 5 may be the same as or different from each other. The groups represented by -Y 2 -R 20 -Y 3 - and -Y 4 -R 21 -Y 5 - in such a general formula (7) are composed of groups formed by a proton donor releasing two protons. As the proton donor, an organic acid having at least two carboxyl groups or hydroxyl groups in the molecule is preferable, and further, an aromatic compound having at least two carboxyl groups or hydroxyl groups on adjacent carbons constituting an aromatic ring is preferable, and an aromatic compound having at least two hydroxyl groups on adjacent carbons constituting an aromatic ring is more preferable. For example, catechol, pyrogallol, 1,2-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,2'-biphenol, 1,1'-bi-2-naphthol, salicylic acid, 1-hydroxy-2-naphthoic acid, 3-hydroxy-2-naphthoic acid, chloranilic acid, tannic acid, 2-hydroxybenzyl alcohol, 1,2-cyclohexanediol, 1,2-propanediol, glycerin, etc. can be mentioned. Among these, catechol, 1,2-dihydroxynaphthalene, and 2,3-dihydroxynaphthalene are more preferable.

[0073] Also, Z in the general formula (7) 1The group represents an organic or aliphatic group having an aromatic ring or heterocycle. Specific examples of these include aliphatic hydrocarbon groups such as methyl, ethyl, propyl, butyl, hexyl, and octyl groups; aromatic hydrocarbon groups such as phenyl, benzyl, naphthyl, and biphenyl groups; glycidyloxy groups such as glycidyloxypropyl, mercaptopropyl, and aminopropyl groups; alkyl groups having mercapto or amino groups; and reactive substituents such as vinyl groups. Among these, methyl, ethyl, phenyl, naphthyl, and biphenyl groups are more preferred in terms of thermal stability.

[0074] A method for producing an adduct between a phosphonium compound and a silane compound involves dissolving a silane compound such as phenyltrimethoxysilane and a proton donor such as 2,3-dihydroxynaphthalene in a flask containing methanol, and then adding a sodium methoxide-methanol solution dropwise under stirring at room temperature. Further, a pre-prepared solution of a tetraphenylphosphonium bromide or other tetra-substituted phosphonium halide dissolved in methanol is added dropwise under stirring at room temperature, causing crystals to precipitate. The precipitated crystals are then filtered, washed with water, and vacuum-dried to obtain the adduct between the phosphonium compound and the silane compound. However, the method is not limited to this.

[0075] The content of the curing catalyst is preferably 0.05% by mass or more, more preferably 0.08% by mass or more, and particularly preferably 0.10% by mass or more, relative to the total epoxy resin molding material. By setting the content of the curing catalyst to be above the lower limit, the curability of the epoxy resin molding material during transfer molding can be effectively improved. On the other hand, the content of the curing catalyst is preferably 2.0% by mass or less, more preferably 1.0% by mass or less, and particularly preferably 0.5% by mass or less, relative to the total epoxy resin molding material. By setting the content of the curing catalyst to be below the upper limit, the fluidity during sealing can be improved, contributing to improved filling performance.

[0076] [wax] The epoxy resin molding material may contain wax as a release agent, if necessary. Examples of waxes include natural waxes such as carnauba wax, synthetic waxes such as ester waxes, montanic acid ester waxes, and polyethylene oxide wax, and higher fatty acids such as zinc stearate and their metal salts.

[0077] The amount of wax added is, for example, 0.05% by mass or more and 2.0% by mass or less relative to the total epoxy resin molding material. The lower limit of the amount of wax added is preferably 0.1% by mass or more, and more preferably 0.2% by mass or more, relative to the total epoxy resin molding material. The upper limit of the amount of wax added is preferably 1.5% by mass or less, and more preferably 1.0% by mass or less, relative to the total epoxy resin molding material. By adding wax within the above ranges, the resulting epoxy resin molding material has excellent fluidity and filling properties during transfer molding.

[0078] [Coupling agent] The epoxy resin molding material may contain a coupling agent, such as a silane coupling agent, if necessary. Examples of coupling agents include epoxysilanes, aminosilanes, ureidosilanes, and mercaptosilanes.

[0079] Examples of epoxysilanes include γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. Examples of aminosilanes include γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, N-phenylγ-aminopropyltriethoxysilane, N-phenylγ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropyltriethoxysilane, N-6-(aminohexyl)3-aminopropyltrimethoxysilane, and N-(3-(trimethoxysilylpropyl)-1,3-benzenedimethanane. Examples of ureidosilanes include γ-ureidopropyltriethoxysilane and hexamethyldisilazane. Primary aminosilanes The amino moiety may be protected by reacting with a ketone or aldehyde to form a latent aminosilane coupling agent. The aminosilane may also have a secondary amino group. Examples of mercaptosilanes include γ-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and silane coupling agents that exhibit similar functions to mercaptosilane coupling agents upon thermal decomposition, such as bis(3-triethoxysilylpropyl)tetrasulfide and bis(3-triethoxysilylpropyl)disulfide. These silane coupling agents may also be formulated after being pre-hydrolyzed. These silane coupling agents may be used individually or in combination of two or more.

[0080] From the viewpoint of continuous moldability, mercaptosilane is preferred; from the viewpoint of fluidity, aminosilane is preferred; and from the viewpoint of adhesion, epoxysilane is preferred.

[0081] The lower limit of the content of a coupling agent, such as a silane coupling agent, that can be used in epoxy resin molding materials is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and particularly preferably 0.1% by mass or more, relative to the total epoxy resin molding material. If the lower limit of the content of the coupling agent, such as a silane coupling agent, is within the above range, the interfacial strength between the epoxy resin and the inorganic filler will not decrease, and good vibration resistance can be obtained. The upper limit of the content of the coupling agent, such as a silane coupling agent, is preferably 1% by mass or less, more preferably 0.8% by mass or less, and particularly preferably 0.6% by mass or less, relative to the total epoxy resin molding material. If the upper limit of the content of the coupling agent, such as a silane coupling agent, is within the above range, the interfacial strength between the epoxy resin and the inorganic filler will not decrease, and good vibration resistance can be obtained. Furthermore, if the content of the coupling agent, such as a silane coupling agent, is within the above range, an increase in the water absorption of the cured epoxy resin molding material is prevented.

[0082] [Other additives] In addition to the above components, the epoxy resin molding material of this embodiment may optionally contain other additives such as colorants, flame retardants, stress reducers, and adhesion aids. These may be used individually or in combination of two or more.

[0083] Although embodiments of the present invention have been described above, these are merely examples, and various other configurations can be adopted. Furthermore, the present invention is not limited to the embodiments described above, and modifications, improvements, etc., within the scope of achieving the objectives of the present invention are included. Examples of reference formats are provided below. 1. A tablet-shaped epoxy resin molding material, Epoxy resin and Including fibrous or needle-shaped fillers, The cross-sectional area is 3 cm 2 More than 100cm 2 The following: In the tablet-shaped epoxy resin molding material, the specific gravity is G, the mass is M (g), and the volume is V (cm³), as measured in accordance with JIS 6911:2006. 3 A tablet-shaped epoxy resin molding material in which, when given [(M / G) / V] × 100, the compressibility ratio is 70% or more and 95% or less. 2. The tablet-shaped epoxy resin molding material described in 1. A tablet-shaped epoxy resin molding material in which the volume-average fiber length of the fibrous or needle-shaped filler, as measured by the following procedure A, is 5 μm or more and 500 μm or less. (Procedure A) After dissolving the tablet-shaped epoxy resin molding material in acetone to remove the resin components, the insoluble matter is dispersed on a glass plate, and the filler in the insoluble matter is photographed using an optical microscope. The fiber length is then measured using an image analysis device. The average fiber length, based on the volume of the 100 fillers with the longest fiber length, is defined as the volume-average fiber length. 3. A tablet-shaped epoxy resin molding material as described in 1. or 2., Let L be the volume-average fiber length of the fibrous or needle-shaped filler measured in procedure A below, and let D be the number-average fiber diameter of the fibrous or needle-shaped filler measured in procedure B below. A tablet-shaped epoxy resin molding material having an L / D ratio of 3 to 100. (Procedure A) After dissolving the tablet-shaped epoxy resin molding material in acetone to remove the resin components, the insoluble matter is dispersed on a glass plate, and the filler in the insoluble matter is photographed using an optical microscope. The fiber length is then measured using an image analysis device. The average fiber length, based on the volume of the 100 fillers with the longest fiber length, is defined as the volume-average fiber length. (Procedure B) Using a scanning electron microscope, 100 cross-sections of fibrous filler are measured from the cross-section of the tablet-shaped epoxy resin molded material, and the average of the minimum diameters of each fiber cross-section is determined as the number-average fiber diameter. 4. A tablet-shaped epoxy resin molding material as described in 1. or 2., A tablet-shaped epoxy resin molding material wherein the fibrous or needle-shaped filler comprises one or more selected from the group consisting of wollastonite fibers, glass fibers, metal fibers, carbon fibers, fibrous aluminum oxide, aramid fibers, silicon carbide whiskers, silicon nitride whiskers, and potassium titanate whiskers. 5. A tablet-shaped epoxy resin molding material as described in 1. or 2., A tablet-shaped epoxy resin molding material having a spiral flow of 20 cm or more, as measured according to the following procedure. (procedure) Using a low-pressure transfer molding machine, the tablet-shaped epoxy resin molding material is injected into a spiral flow measurement mold conforming to EMMI-1-66 under the conditions of a mold temperature of 175°C, injection pressure of 6.9 MPa, and curing time of 120 seconds, and the flow length (cm) is measured. 6. A tablet-shaped epoxy resin molding material as described in 1. or 2., A tablet-shaped epoxy resin molding material in which the content of the fibrous or needle-shaped filler is 5% by mass or more and 80% by mass or less of the tablet-shaped epoxy resin molding material by 100% by mass. 7. A tablet-shaped epoxy resin molding material as described in 1. or 2., A tablet-shaped epoxy resin molding material wherein the epoxy resin comprises a cresol novolac type epoxy resin and / or a bisphenol A type epoxy resin. 8. A tablet-shaped epoxy resin molding material as described in 1. or 2., A tablet-shaped epoxy resin molding material comprising one or more curing catalysts selected from the group consisting of amine-based catalysts and phosphorus-based catalysts. 9. A tablet-shaped epoxy resin molding material as described in 1. or 2., 5cm 3 More than 1500cm 3 A tablet-shaped epoxy resin molding material having the following volume. 10. A tablet-shaped epoxy resin molding material as described in 1. or 2., A tablet-shaped epoxy resin molding material used for magnet fixing, electronic control unit sealing, coil sealing, or stator core sealing. 11. Columnar tablets formed from the tablet-shaped epoxy resin molding material described in 1. or 2. 12. A step of obtaining an epoxy resin molding material by melt-kneading an epoxy resin composition containing epoxy resin and fibrous or needle-shaped filler, The process includes obtaining a columnar tablet using the obtained epoxy resin molding material, The cross-sectional area of ​​the columnar tablet is 3 cm 2 More than 100cm 2 The following: In the aforementioned columnar tablet, the specific gravity measured in accordance with JIS 6911:2006 is G, the mass is M (g), and the volume is V (cm³). 3 When this is the case, the compression ratio calculated from [(M / G) / V] × 100 is between 70% and 95%. A method for manufacturing columnar tablets. [Examples]

[0084] The present invention will be described in detail below with reference to examples, but the present invention is not limited in any way to the descriptions of these examples.

[0085] (Examples 1-3, Comparative Examples 1 and 2) <Manufacturing of tablet-shaped epoxy resin molding materials> A granular epoxy resin composition was obtained by kneading a mixture of materials containing each component according to the proportions shown in Table 1 using a heated roll, cooling it into a sheet, and then pulverizing it. The kneading conditions for the heated roll were a rotation speed of 20 rpm, a temperature of 120°C, and a kneading time of 5 to 10 minutes.

[0086] The details of each component in Table 1 regarding the raw materials of the epoxy resin composition are as follows. • Fibrous or needle-shaped filler: Glass fiber (manufactured by Nitto Boseki Co., Ltd., CS3E479) Other inorganic fillers: Crushed silica (manufactured by Tatsumori Co., Ltd., RD-8) • Coloring agent: Carbon black • Epoxy resin: Novolac-type epoxy resin (DIC Corporation, N680) • Hardener: Phenolic novolac resin 1 (manufactured by Sumitomo Bakelite Co., Ltd., PR51470) • Hardener: Phenolic novolac resin 2 (manufactured by Sumitomo Bakelite Co., Ltd., PR51714) • Curing catalyst: Amine-based catalyst (manufactured by Shikoku Chemicals Co., Ltd., 2PZ-PW) • Wax: Carnauba wax • Wax: Calcium stearate • Low-stress agent: Organic modified silicone oil (Dow Corporation, FZ-3730) • Adhesion enhancer: Triazine compound (manufactured by Shikoku Chemicals, VD-5)

[0087] The epoxy resin composition obtained above was compressed using a tablet machine (BARPRESS, manufactured by Kikusui Seisakusho Co., Ltd.) under the molding pressure and compression time conditions shown in Table 2 to obtain tablets weighing 8 g, with a tablet diameter of 14 mm and a tablet height of 29 mm. Based on the above, tablet-shaped epoxy resin molding materials (tablets) with different compression ratios were prepared for Examples 1-3 and Comparative Examples 1 and 2.

[0088] <Compression ratio> The obtained tablet-shaped epoxy resin molding material was then analyzed according to JIS 6911:2006, determining its specific gravity G, mass M (g), and volume V (cm³). 3 The following parameters were measured: G, M, and V. The compression ratio (%) was calculated using the formula: [(M / G) / V] × 100. The results are shown in Table 2.

[0089] <Volume-average fiber length> After removing the resin components from the epoxy resin molding material by dissolving it in acetone, the insoluble matter was dispersed on a glass plate. Fillers in the insoluble matter were photographed using an optical microscope, and the fiber length was measured using an image analysis device. The average fiber length (μm) was defined by the following formula, which is based on the volume of the fibers in the 100 fillers with the longest fibers. The results are shown in Table 2. Lv = Σ(L × v) / Σv Σ represents a set, L represents the length of each individual fiber, and v represents the volume of each individual fiber.

[0090] [Table 1]

[0091] The following items were evaluated for the obtained epoxy resin composition and the tablet-shaped epoxy resin molding material.

[0092] [Table 2]

[0093] <Spiral Flow> Using a low-pressure transfer molding machine (KTS-15, manufactured by Kotaki Seiki Co., Ltd.), the obtained epoxy resin composition was injected into a spiral flow measurement mold conforming to EMMI-1-66 under the conditions of a mold temperature of 175°C, injection pressure of 6.9 MPa, and holding pressure time of 120 seconds, and the flow length was measured.

[0094] <Bending test: Bending modulus> The obtained tablets were injected using a transfer molding machine under the conditions of a mold temperature of 175°C, injection pressure of 9.8 MPa, and curing time of 120 seconds to obtain test specimens with a width of 10 mm, a thickness of 4 mm, and a length of 80 mm. The flexural modulus (GPa) of the obtained test specimens at room temperature was measured in accordance with JIS K 6911.

[0095] <k1c> In accordance with the KIc method specified in ASTM D5045-14, the obtained tablet-shaped epoxy resin molding material (columnar tablet) was made to a size of 50 mm in length, 5 mm in width B, and 10 mm in thickness W. A notch with a depth of 3.5 mm in the thickness direction was formed in the center in the length direction, and the material was cured at 175°C for 4 hours to obtain a cured product. Furthermore, a scratch with a depth of 0.1 mm in the thickness direction was made at the tip of the notch in the cured product using a razor blade, and a test specimen with a total crack length a = 3.6 mm was prepared. Subsequently, as outlined in Figure 1, a three-point bending test was performed on the obtained test specimen 10 using a tensile-compression testing machine (STB-1225S Tensilon, manufactured by Orientec Co., Ltd.) at a measurement temperature of 25°C, a speed of 10 mm / min, and a support distance S = 40 mm. The fracture toughness value (K1c(MPa·m)) was determined based on the following formula. 1 / 2 The following formula was calculated. In the formula below, P Q This represents the maximum load (N). The tensile and compression testing machine shown in Figure 1 is equipped with a loading pin 12 with a diameter of 10 mm and two rounded support points 14 with a radius. KI C =((P Q ×S) / (B×W 3 / 2 )) × f(a / W) However, f(a / W)=(3(a / W) 1 / 2 [1.99-(a / W)(1-a / W){2.15-3.9(a / W)+2.7(a / W) 2 ]) / (2{1+2(a / W)}{1-(a / W)} 3 / 2 ) When the fracture toughness value of Comparative Example 1 calculated above is normalized to 1.0, the relative fracture toughness values ​​of Examples 1-3 and Comparative Examples 1 and 2 are shown in Table 2.

[0096] <Evaluation of damage during transport> The likelihood of damage during transport was evaluated as follows: Multiple tablets obtained were placed in a box, and a transport experiment was conducted in this state by applying a predetermined vibration for a predetermined time. The height of the tablets before and after the transport experiment was measured with calipers. If the standard deviation of the tablet height after transport was within 20% of the average tablet height before transport (immediately after molding), it was judged that there was little damage during transport and the transport fragility was good. If it exceeded 20%, it was judged that the transport fragility was poor.

[0097] Based on these results, the epoxy resin molding materials of Examples 1-3 showed better resistance to breakage during transport compared to Comparative Example 1. Furthermore, the epoxy resin molding materials of Examples 1-3 were found to have higher mechanical strength as well as fracture toughness compared to Comparative Example 2. The epoxy resin molding materials of Examples 1 to 3 can be suitably used for magnet fixing, electronic control unit sealing, coil sealing, or stator core sealing.

[0098] This application claims priority based on Japanese Patent Application No. 2024-058574, filed on April 1, 2024, and incorporates all of its disclosures herein. [Explanation of Symbols]

[0099] 10 test specimens 12 Loading pins 14 Round pivot point

Claims

1. A tablet-shaped epoxy resin molding material, It is a cylindrical tablet, Epoxy resin and Including fibrous or needle-shaped fillers, The volume-average fiber length of the fibrous or needle-shaped filler, as measured by the following procedure A, is 5 μm or more and 500 μm or less. The content of the fibrous or needle-shaped filler is 5% by mass or more and 80% by mass or less in 100% by mass of the tablet-shaped epoxy resin molding material. The cross-sectional area of ​​the cylindrical tablet in the direction perpendicular to the height direction is π × (0.7) 2 cm². ２ More than 100cm ２ The following conditions apply: The height of the cylindrical tablet is 10 mm or more and 300 mm or less, or the volume of the cylindrical tablet is π × (0.7)² × (2.9) cm³ or more and 1500 cm³. In the tablet-shaped epoxy resin molding material, the specific gravity is G, the mass is M (g), and the volume is V (cm³), as measured in accordance with JIS 6911:2006. ３ A tablet-shaped epoxy resin molding material in which, when given the formula [(M / G) / V] × 100, the compressibility is 70% or more and 95% or less. (Procedure A) After dissolving the tablet-shaped epoxy resin molding material in acetone to remove the resin components, the insoluble matter is dispersed on a glass plate, and the filler in the insoluble matter is photographed using an optical microscope. The fiber length is then measured using an image analysis device. The average fiber length, based on the volume of the 100 fillers with the longest fiber length, is defined as the volume-average fiber length.

2. A tablet-shaped epoxy resin molding material according to claim 1, When L is the volume-average fiber length of the fibrous or needle-shaped filler measured in procedure A below, and D is the number-average fiber diameter of the fibrous or needle-shaped filler measured in procedure B below, A tablet-shaped epoxy resin molding material having an L / D ratio of 3 or more and 100 or less. (Procedure A) After dissolving the tablet-shaped epoxy resin molding material in acetone to remove the resin components, the insoluble matter is dispersed on a glass plate, and the filler in the insoluble matter is photographed using an optical microscope. The fiber length is then measured using an image analysis device. The average fiber length, based on the volume of the 100 fillers with the longest fiber length, is defined as the volume-average fiber length. (Procedure B) Using a scanning electron microscope, 100 cross-sections of fibrous filler are measured from the cross-section of the tablet-shaped epoxy resin molded material, and the average of the minimum diameters of each fiber cross-section is determined as the number-average fiber diameter.

3. A tablet-shaped epoxy resin molding material according to claim 1 or 2, A tablet-shaped epoxy resin molding material wherein the fibrous or needle-shaped filler comprises one or more selected from the group consisting of wollastonite fibers, glass fibers, metal fibers, carbon fibers, fibrous aluminum oxide, aramid fibers, silicon carbide whiskers, silicon nitride whiskers, and potassium titanate whiskers.

4. A tablet-shaped epoxy resin molding material according to claim 1 or 2, A tablet-shaped epoxy resin molding material having a spiral flow of 20 cm or more, as measured according to the following procedure. (procedure) Using a low-pressure transfer molding machine, the tablet-shaped epoxy resin molding material is injected into a spiral flow measurement mold conforming to EMMI-1-66 under the conditions of a mold temperature of 175°C, an injection pressure of 6.9 MPa, and a curing time of 120 seconds, and the flow length (cm) is measured.

5. A tablet-shaped epoxy resin molding material according to claim 1 or 2, A tablet-shaped epoxy resin molding material wherein the epoxy resin comprises a cresol novolac type epoxy resin and / or a bisphenol A type epoxy resin.

6. A tablet-shaped epoxy resin molding material according to claim 1 or 2, A tablet-shaped epoxy resin molding material comprising one or more curing catalysts selected from the group consisting of amine-based catalysts and phosphorus-based catalysts.

7. A tablet-shaped epoxy resin molding material according to claim 1 or 2, A tablet-shaped epoxy resin molding material used for magnet fixing, electronic control unit sealing, coil sealing, or stator core sealing.

8. A step of obtaining an epoxy resin molding material by melt-kneading an epoxy resin composition containing epoxy resin and fibrous or needle-shaped fillers, The process includes obtaining a cylindrical tablet using the obtained epoxy resin molding material, The volume-average fiber length of the fibrous or needle-shaped filler, as measured by procedure A below, is 5 μm or more and 500 μm or less. The content of the fibrous or needle-shaped filler is 5% by mass or more and 80% by mass or less in 100% by mass of the epoxy resin molding material. The cross-sectional area of ​​the cylindrical tablet in the direction perpendicular to the height direction is π × (0.7)² cm². ２ More than 100cm ２ The following conditions apply: The height of the cylindrical tablet is 10 mm or more and 300 mm or less, or the volume of the cylindrical tablet is π × (0.7)² × (2.9) cm³ or more and 1500 cm³. In the cylindrical tablet, the specific gravity measured in accordance with JIS 6911:2006 is G, the mass is M (g), and the volume is V (cm³). ３ When this is the case, the compression ratio calculated from [(M / G) / V] × 100 is between 70% and 95%. A method for manufacturing columnar tablets. (Procedure A) After dissolving the epoxy resin molding material in acetone to remove the resin components, the insoluble matter is dispersed on a glass plate, the filler in the insoluble matter is photographed using an optical microscope, and the fiber length is measured using an image analysis device. The average fiber length, based on the volume of the 100 fillers with the longest fiber length, is defined as the volume-average fiber length.

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