Epoxy resin composition and cured product

Abstract

To provide an epoxy resin composition that gives a cured product having excellent high temperature properties, such as heat resistance, heat transfer rate, and high temperature elastic modulus, and further provide a cured product including the same.SOLUTION: An epoxy resin composition comprises an epoxy resin and a curing agent. The epoxy resin composition gives a crystalline cured product by using, as an epoxy resin component, a bifunctional epoxy resin represented by the general formula (1) and, as curing agent components, a bifunctional phenolic compound and a polyfunctional phenolic resin.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an insulating material for electrical and electronic materials such as semiconductor encapsulation, laminate, and heat dissipation substrate with excellent reliability, an epoxy resin composition useful as a carbon fiber reinforced composite material, and a polymer using the same.

Background Art

[0002] Conventionally, as a method for encapsulating electrical and electronic components such as diodes, transistors, and integrated circuits, and semiconductor devices, for example, an encapsulation method using an epoxy resin or a silicon resin, or a hermetic sealing method using glass, metal, ceramic, etc. has been adopted. In recent years, resin encapsulation by transfer molding, which enables mass production along with improved reliability and has cost advantages, has become the mainstream.

[0003] In the resin composition used for resin encapsulation by transfer molding, an encapsulation material composed of an epoxy resin and a resin composition mainly composed of a phenolic resin as a curing agent is generally used.

[0004] An epoxy resin composition used for the purpose of protecting elements such as power devices is desired to further improve heat resistance, heat dissipation, and low thermal expansion in order to cope with a large amount of heat released by the elements.

[0005] In view of the above background, for example, Patent Document 1 proposes a liquid crystalline epoxy resin having a rigid mesogenic group and an epoxy resin composition using the same. However, although the liquid crystallinity of the cured product obtained therefrom can be confirmed, it does not have a clear melting point and is not sufficient in terms of heat resistance, high thermal conductivity, low thermal expansion, low moisture absorption, etc. Patent Document 2 discloses an epoxy resin composition and a cured product using an epoxy resin having a bisphenol-based mesogenic structure and a curing agent mainly composed of a bifunctional phenolic compound, and it is disclosed that a crystalline cured product is obtained. However, since it is a reaction between bifunctional components, in addition to insufficient curability, crosslinking reaction hardly occurs, resulting in insufficient heat resistance and insufficient thermal conductivity. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2004-331811 [Patent Document 2] Japanese Patent Publication No. 2012-233206 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Therefore, the object of the present invention is to solve the above problems and provide an epoxy resin composition that gives a crystalline cured product with excellent moldability, heat resistance, low moisture absorption, and high thermal conductivity, and further to provide a cured product using the same. [Means for solving the problem]

[0008] The present inventors have discovered that when a specific bifunctional curing agent, which reacts two-dimensionally, is combined with a specific polyvalent phenolic resin as a curing agent for an epoxy resin having a specific structure, a crystalline cured product having a crosslinked structure is obtained, and physical properties such as heat resistance, low moisture absorption, high-temperature modulus, thermal conductivity, and flame retardancy are specifically improved, leading to the present invention.

[0009] The present invention relates to an epoxy resin composition comprising an epoxy resin and a curing agent, wherein 50 wt% or more of the epoxy resin is a bifunctional epoxy resin, 20 to 90 wt% of the curing agent is a bifunctional phenol compound, and 10 to 80 wt% of the curing agent is a polyfunctional phenol resin, and provides an epoxy resin composition that yields a crystalline cured product, and a crystalline epoxy resin cured product obtained by curing this composition.

[0010] The above-mentioned bifunctional epoxy resin is represented by the following formula (1). [ka] (However, X represents a single bond, -O-, -CO-, -φ-, -O-φ-O- (hereinafter, φ represents a phenylene group). n represents a number from 0 to 5.)

[0011] The above-mentioned difunctional phenol compound is represented by the following formula (2). [ka] (However, Y represents a single bond, -O-, -CO-, -φ-, and -O-φ-O-. n represents a number from 0 to 15.)

[0012] The above-mentioned polyfunctional phenolic resin is represented by the following formula (3). [ka] (However, Z independently represents a hydrocarbon group having 6 to 20 carbon atoms, and R1 and R2 independently represent a hydrogen atom or a hydrocarbon group having 1 to 9 carbon atoms. Here, R1 and R2 include cyclic structures that are adjacent to each other and linked together. Also, m represents a number from 0.1 to 15.)

[0013] Furthermore, the present invention relates to a crystalline cured product obtained by curing the above-mentioned epoxy resin composition.

[0014] Preferably, the cured product has an endothermic peak (melting point) associated with crystal melting in scanning differential thermal analysis that is in the range of 200°C to 350°C, or the amount of heat absorbed (in terms of resin components) associated with crystal melting in scanning differential thermal analysis is 10 J / g or more. [Effects of the Invention]

[0015] The epoxy resin composition of the present invention is excellent in moldability and reliability, and provides a molded product excellent in high heat resistance, low water absorption, high thermal conductivity, low thermal expansion, etc. It is suitably applied to insulating materials for electrical and electronic materials such as semiconductor encapsulation, laminates, and heat dissipation substrates, and further to composite materials such as fiber reinforced composite materials and molding materials for mechanical parts. Excellent high heat dissipation, high heat resistance and high dimensional stability are exhibited. The reason for such specific effects is that a specific epoxy resin is reacted with a specific bifunctional phenolic curing agent to form a unit of a crystalline two-dimensional molecular chain having a high melting point and a high elastic modulus at high temperatures, and at the same time, a specific polyvalent phenol resin is used as a curing agent. By maintaining crystallinity and introducing a crosslinked structure, it becomes possible to impart high heat resistance, low water absorption, thermal conductivity, low thermal expansion, flame retardancy, etc. to the cured product.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, the present invention will be described in detail.

[0017] In the epoxy resin composition of the present invention, the epoxy resin contains, as an essential component, an epoxy resin represented by the following general formula (1).

Chemical formula

[0018] In formula (1), X represents a single bond, -CH2-, -O-, -CO-, -φ-, -O-φ-O-. From the viewpoint of compatibility with the curing agent, -CH2-, -O-, -CO-, -O-φ-O- are preferable, and from the viewpoint of heat resistance when formed into a cured product, a single bond and -φ- are preferable.

[0019] n is the number of repetitions and represents a number from 0 to 5. When it is a mixture of a plurality of compounds with different numbers of repetitions, the average value of n (Σn / Σ number of molecules) is in the range of 0 to 5. As an epoxy resin composition, in order to increase the filling rate of the inorganic filler, it is desirable to have a low viscosity, and the preferable range of n (average value) is 0.1 to 2.0.

[0020] The epoxy equivalent (g / eq.) of the epoxy resin used in the present invention is usually in the range of 150 to 600, but from the viewpoint of increasing the filling rate of inorganic fillers and improving fluidity, a low viscosity is preferable, and an epoxy equivalent in the range of 150 to 500 is preferred.

[0021] The epoxy resin used in this invention is preferably one that is crystalline at room temperature. The preferred melting point range is 50 to 250°C, and more preferably 70 to 200°C. If the melting point is lower than this range, the handling properties of the epoxy resin composition will decrease due to blocking, and if it is higher than this range, the compatibility with the curing agent and solubility in solvents will decrease.

[0022] The purity of the epoxy resin used in this invention, particularly the amount of hydrolyzable chlorine, should be low from the viewpoint of improving the reliability of the electronic components to which it is applied. Although not particularly limited, it is preferably 1000 ppm or less, and more preferably 500 ppm or less. In this invention, hydrolyzable chlorine refers to the value measured by the following method: 0.5 g of the sample is dissolved in 30 ml of dioxane, 10 ml of 1N-KOH is added, boiled under reflux for 30 minutes, cooled to room temperature, 100 ml of 80% acetone water is added, and the value is obtained by potentiometric titration with a 0.002 N-AgNO3 aqueous solution.

[0023] In addition to the epoxy resin of formula (1) used as an essential component, the epoxy resin composition of the present invention may also contain other epoxy resins having two or more epoxy groups in their molecule as epoxy resin components. For example, divalent phenols such as bisphenol A, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfide, fluorenebisphenol, resorcinol, catechol, t-butylcatechol, t-butylhydroquinone, allylated bisphenol A, allylated bisphenol F, allylated phenol novolac, or phenol novolac, bisphenol A novolac, o-cresol novolac, m-cresol novolac, p-cresol novolac, xylenol novolac, poly-p-hydroxystain Examples include phenylethanol, tris-(4-hydroxyphenyl)methane, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, fluoroglycinol, pyrogallol, t-butylpyrogallol, allylated pyrogallol, polyallylated pyrogallol, 1,2,4-benzenetriol, 2,3,4-trihydroxybenzophenone, phenol aralkyl resins, naphthol aralkyl resins, dicyclopentadiene resins, and other phenols with a valency of 3 or higher, or glycidyl ethers derived from halogenated bisphenols such as tetrabromobisphenol A. One or more of these epoxy resins can be used.

[0024] The proportion of the epoxy resin of formula (1) used in the epoxy resin composition of the present invention is 50 wt% or more of the total epoxy resin, preferably 70 wt% or more, and more preferably 80 wt% or more. If the proportion is less than this, the effect of improving physical properties such as thermal conductivity when cured will be small.

[0025] In the epoxy resin composition of the present invention, the curing agent contains an epoxy resin represented by the following general formula (2) as an essential component. [ka]

[0026] In formula (2), Y represents a single bond, -O-, -CO-, -φ-, and -O-φ-O-. Here, φ represents a phenylene group. From the viewpoint of compatibility with epoxy resin, -CH2-, -O-, -CO-, and -O-φ-O- are preferred, and from the viewpoint of heat resistance when cured, a single bond and -φ- are preferred.

[0027] The amount of difunctional phenol compound used as a curing agent is 20 to 90 wt% of the total curing agent, preferably 40 to 80 wt%, and more preferably 50 to 70 wt%. If the amount is less than this, the degree of crystallinity of the cured product will not be sufficient, and the effect of improving physical properties such as heat resistance and thermal conductivity will be small. If the amount is more than this, the amount of polyfunctional phenol resin used will decrease, resulting in poor moldability and reduced flame retardancy and moisture resistance.

[0028] Furthermore, the curing agent used in the epoxy resin composition of the present invention comprises, together with the above-mentioned difunctional phenol compound, a polyfunctional phenol resin represented by the following general formula (3) as an essential component. [ka]

[0029] In formula (3), Z independently represents a hydrocarbon group having 6 to 20 carbon atoms. From the viewpoint of low water absorption, flame retardancy, and low dielectric properties when cured, Z is preferably an aralkyl structure having an aromatic structure with a benzene or naphthalene skeleton, and -CH2-φ-CH2-, -CHMe-φ-CHMe-, and -CH2-φ-φ-CH2- are particularly preferred. Here, φ represents a phenylene group.

[0030] In formula (3), R1 and R2 represent hydrogen atoms or, independently, hydrocarbon groups having 1 to 9 carbon atoms. From the viewpoint of moldability, hydrogen atoms are preferred, while hydrocarbon groups are desirable from the viewpoint of low water absorption and low dielectric properties. Furthermore, R1 and R2 are adjacent to each other and include a cyclic structure linked to them. From the viewpoint of heat resistance, low water absorption, low thermal expansion, and flame retardancy, it is desirable that the cyclic structure be a naphthalene skeleton.

[0031] m represents the number of repeats, ranging from 0.1 to 15. Polyfunctional phenolic resins are typically mixtures of multiple compounds with different repeat numbers. In this case, the average value of m (Σm / Σ number of molecules) is in the range of 0.1 to 15, preferably 0.5 to 10, and more preferably 1.0 to 5. If it is smaller than this range, the improvement in moldability, heat resistance, flame retardancy, and low water absorption is small. If it is larger than this range, the viscosity increases, and the fluidity during molding and filler filling properties decrease.

[0032] The amount of the polyfunctional phenol compound of formula (3) used as a curing agent is 10 to 80 wt% of the total curing agent, preferably 30 to 80 wt%, and more preferably 40 to 80 wt%. Using less than this amount will worsen moldability and reduce the effect of improving the physical properties of the cured product, such as heat resistance, moisture resistance, and flame retardancy. Using more than this amount will decrease the crystallinity of the cured product, and reduce its high-temperature modulus, thermal conductivity, and low thermal expansion.

[0033] The preferred hydroxyl group equivalent of the above-mentioned polyfunctional phenolic resin is in the range of 150 to 350 g / eq., and more preferably in the range of 170 to 300 g / eq. If it is lower than this range, the improvement effect on flame retardancy, low water absorption, etc. is small, and if it is higher than this range, moldability decreases, and the crosslinking density of the cured product decreases, resulting in a decrease in heat resistance, etc.

[0034] The preferred softening point of the above-mentioned polyfunctional phenolic resin is 50 to 200°C, and more preferably 70 to 150°C. If it is lower than this, the handling properties will decrease due to blocking, etc., when used in an epoxy resin composition, and if it is higher than this, it is preferable that it be below the above upper limit from the viewpoint of compatibility with epoxy resins and the resulting curability and moldability.

[0035] The ratio of the difunctional epoxy resin of formula (1), the difunctional phenol compound of formula (2), and the polyfunctional phenol resin of formula (3) is preferably such that B(1+a / b) / (A+B+C) is in the range of 0.30 to 0.90, where A is the weight of the difunctional epoxy resin, a is the epoxy equivalent, B is the weight of the difunctional phenol compound, b is the hydroxyl group equivalent, and C is the weight of the polyfunctional phenol resin. This corresponds to the proportion of units that exhibit crystallinity formed by the reaction of the difunctional epoxy resin and the difunctional phenol compound in the cured product. If it is smaller than this, crystallinity decreases or does not appear at all, and properties such as high thermal conductivity and high-temperature modulus decrease. If it is larger than this, the crosslinking density decreases, and properties such as heat resistance, flame retardancy and low water absorption deteriorate. B(1+a / b) / (A+B+C) is more preferably in the range of 0.30 to 0.80.

[0036] In addition to the difunctional phenol compound of formula (2) and the polyfunctional phenol resin of formula (3), other commonly known curing agents can be used in combination with the epoxy resin composition of the present invention. Examples include amine-based curing agents, acid anhydride-based curing agents, phenol-based curing agents, polymercaptan-based curing agents, polyaminoamide-based curing agents, isocyanate-based curing agents, and blocked isocyanate-based curing agents. The amount of these other curing agents should be appropriately determined considering the type of curing agent used and the physical properties of the resulting thermally conductive epoxy resin molded article. However, even when using other curing agents, their amount is preferably less than 50 wt%, more preferably less than 30 wt%, relative to the total amount of curing agent.

[0037] In the epoxy resin composition of the present invention, the mixing ratio of epoxy resin to curing agent is preferably in the range of 0.8 to 1.5 in terms of equivalent weight of epoxy groups to functional groups in the curing agent. This range is preferable in order to prevent unreacted epoxy groups or functional groups in the curing agent from remaining after curing, which would reduce the reliability of the insulating material for electronic components.

[0038] The epoxy resin composition of the present invention preferably contains an inorganic filler. In this case, the amount of inorganic filler added is usually 50 to 96 wt% of the epoxy resin composition, but preferably 60 to 94 wt%, and more preferably 70 to 92 wt%. If the amount is less than this, the effects of high thermal conductivity, low thermal expansion, and high heat resistance will not be fully exhibited. These effects improve as the amount of inorganic filler added increases, but the improvement is not proportional to the volume fraction, but rather dramatically increases once the amount exceeds a certain level. These physical properties are due to the controlled effect of the higher-order structure in the polymer state, and since this higher-order structure is mainly achieved on the surface of the inorganic filler, it is considered that a specific amount of inorganic filler is required. On the other hand, from the viewpoint of viscosity and moldability, it is preferable to keep the amount of inorganic filler added below the above upper limit.

[0039] Preferred inorganic fillers include powders such as silica, alumina, boron nitride, aluminum nitride, carbon powder, and carbon fiber powder, as well as fibrous substrates such as glass fibers, carbon fibers, and aramid fibers. The amount used should be 50 wt% or more of the inorganic filler. Furthermore, the inorganic filler is preferably spherical, and is not particularly limited as long as it is spherical, including those with an elliptical cross-section. However, from the viewpoint of improving fluidity, it is especially preferable that it be as close to a perfect sphere as possible. This makes it easier to form close-packed structures such as face-centered cubic structures and hexagonal close-packed structures, and sufficient filling can be obtained. If it is not spherical, as the filling amount increases, friction between the fillers increases, which may lead to a decrease in fluidity or an increase in viscosity before reaching the upper limit of the above-mentioned blending amount, potentially affecting moldability. Therefore, a spherical shape is preferable.

[0040] From the viewpoint of improving thermal conductivity, it is preferable that 50 wt% or more, preferably 80 wt% or more, of the inorganic filler has a thermal conductivity of 5 W / m·K or higher. Suitable inorganic fillers include alumina, aluminum nitride, and crystalline silica. Among these, spherical alumina is superior. In addition, amorphous inorganic fillers, such as fused silica and crystalline silica, may be used in combination as needed, regardless of their shape.

[0041] A known curing accelerator can be used in the epoxy resin composition of the present invention. Examples include amines, imidazoles, organophosphines, Lewis acids, etc. Specifically, these include tertiary amines such as 1,8-diazabicyclo(5,4,0)undecene-7, triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris(dimethylaminomethyl)phenol; imidazoles such as 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, and 2-heptadecylimidazole; organophosphines such as tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine, phenylphosphine, and tris(4-methoxyphenyl)phosphine; tetra-substituted phosphonium tetra-substituted borates such as tetraphenylphosphonium·tetraphenylborate, tetraphenylphosphonium·ethyltriphenylborate, and tetrabutylphosphonium·tetrabutylborate; and tetraphenylborone salts such as 2-ethyl-4-methylimidazole·tetraphenylborate and N-methylmorpholine·tetraphenylborate. These can be used individually or in combination.

[0042] The amount of the curing accelerator added is preferably 0.1 to 10.0 wt parts per 100 wt parts of the total epoxy resin and curing agent. If the amount is less than 0.1 wt, the gelation time will be slow, leading to a decrease in rigidity during the heating reaction and reduced workability. Conversely, if the amount exceeds 10.0 wt, the reaction will proceed during the molding process, making it easy for unfilled areas to occur.

[0043] In the epoxy resin composition of the present invention, in addition to the above components, release agents, coupling agents, thermoplastic oligomers, and other substances that can be used in epoxy resin compositions may be appropriately blended. For example, phosphorus-based flame retardants, flame retardants such as bromine compounds and antimony trioxide, and colorants such as carbon black and organic dyes can be used.

[0044] Wax can be used as a release agent. Examples of waxes include stearic acid, montanic acid, montanic acid esters, and phosphate esters. Epoxysilane can be used as a coupling agent to improve the adhesion between inorganic fillers and resin components. Examples of thermoplastic oligomers include C5 and C9 petroleum resins, styrene resins, indene resins, indene-styrene copolymer resins, indene-styrene-phenol copolymer resins, indene-coumarone copolymer resins, and indene-benzothiophene copolymer resins, which are used to improve the fluidity of epoxy resin compositions during molding and to enhance adhesion to substrates such as lead frames.

[0045] The epoxy resin composition of the present invention contains epoxy resin and a curing agent as essential components, and can be manufactured by uniformly mixing these components (excluding coupling agents), which may include inorganic fillers as needed, using a mixer or the like, adding a coupling agent as needed, and then kneading the mixture using a heated roll, kneader, or the like. There are no particular restrictions on the order in which these components are added, except for the coupling agent. Furthermore, it is possible to pulverize the molten mixture after kneading to produce a powder or form it into tablets.

[0046] The epoxy resin composition of the present invention is suitable for electronic material applications, particularly for encapsulating electronic components and for use in heat dissipation substrates.

[0047] The epoxy resin composition of the present invention can be compounded with a fibrous substrate such as glass fiber to form a composite material. For example, an epoxy resin composition mainly composed of epoxy resin and a curing agent can be dissolved in a commonly used organic solvent, impregnated into a sheet-like fibrous substrate, and heated and dried to partially react the epoxy resin and produce a prepreg.

[0048] To obtain a cured product (molded product) using the epoxy resin composition of the present invention, various heat molding methods such as transfer molding, press molding, casting, injection molding, and extrusion molding can be applied. However, from the viewpoint of mass production, transfer molding is preferred.

[0049] The cured product of the present invention is crystalline, and in scanning differential thermal analysis measured at a heating rate of 10°C / min, the endothermic peak temperature (melting point) associated with the melting of the crystal is usually 150 to 350°C, preferably 170 to 350°C, and more preferably 200 to 350°C.

[0050] Here, we will briefly explain the effect of crystallinity development. Generally, the glass transition temperature is used as an indicator of heat resistance in epoxy resin cured products. This is because ordinary epoxy resin cured products are amorphous (glassy) molded products that do not have crystallinity, and their physical properties change significantly at the glass transition temperature. Therefore, in order to increase the heat resistance of epoxy resin cured products, that is, to raise the glass transition temperature, it is necessary to increase the crosslinking density, but this has the drawback of reducing flexibility and making the product brittle. In contrast, the cured molded product of the present invention is characterized by the development of crystallinity, but since there is little change in physical properties up to the melting point, the melting point can be used as an indicator of heat resistance. Since the melting point of polymeric substances is at a higher temperature than the glass transition temperature, the polymer of the present invention can ensure high heat resistance while maintaining high flexibility by having no crosslinking structure or a low crosslinking density. Furthermore, the development of crystallinity means high intermolecular forces, which suppresses molecular motion, achieves low thermal expansion, and exhibits high thermal diffusivity, improving thermal conductivity. Furthermore, the high packing properties of the molecular chains reduce both water vapor permeability and saturated water absorption, improving water resistance.

[0051] Therefore, a higher degree of crystallinity in the cured product of the present invention is preferable. The degree of crystallinity can be evaluated from the heat of fusion (amount of heat absorbed due to the melting of crystals) measured by scanning differential thermal analysis. A preferred amount of heat absorbed is 10 J / g or more per unit weight of the resin component excluding the filler. More preferably 15 J / g or more, and particularly preferably 20 J / g or more. If it is lower than this, the effect of improving the heat resistance, low thermal expansion, and thermal conductivity of the molded product is small. The amount of heat absorbed referred to here is the amount of heat absorbed obtained by measuring a sample of approximately 10 mg accurately using a differential scanning thermal analyzer under conditions of a nitrogen atmosphere and a heating rate of 10°C / min.

[0052] The cured product of the present invention can be obtained by heating reaction using the molding method described above. While the molding temperature is typically between 80°C and 350°C, it is desirable to react at a temperature lower than the melting point of the molded product in order to increase its crystallinity. A preferred molding temperature is in the range of 130°C to 280°C, more preferably between 160°C and 250°C. A preferred molding time is between 30 seconds and 1 hour, more preferably between 1 minute and 30 minutes. Furthermore, the crystallinity can be further increased by annealing after molding. Typically, the annealing temperature is between 130°C and 250°C, and the time is between 1 hour and 20 hours. However, it is desirable to perform post-curing at a temperature 5°C to 40°C lower than the endothermic peak temperature in differential thermal analysis, for 1 to 24 hours. [Examples]

[0053] The present invention will be specifically described below with reference to the following examples. Synthesis example 27.9 g of 4,4'-dihydroxybiphenyl and 550 g of epichlorohydrin were charged, and 29.5 g of 48.8% sodium hydroxide aqueous solution was added dropwise over 3 hours under reduced pressure (approximately 130 Torr) at 65°C. During this time, the water produced was removed from the system by azeotrope with the epichlorohydrin, and the distilled epichlorohydrin was returned to the system. After the dropwise addition was complete, the reaction was continued for another hour to dehydrate. Then, the mixture was cooled to room temperature, filtered, and washed with water to obtain 26 g of a white powdery solid (epoxy resin 2). The obtained epoxy resin 2 is a biphenyl-based epoxy resin in which X is a single bond in general formula (1). GPC measurements showed that 97.8% was n=0 and 2.2% was n=1 of general formula (1). The epoxy equivalent was 153 g / eq., the hydrolyzable chlorine content was 280 ppm, and the melting point obtained by scanning differential thermal analysis at a heating rate of 10°C / min was 162°C. Hydrolyzable chlorine was measured using the method described above.

[0054] Examples 1-6, Comparative Examples 1-7 As bifunctional epoxy resins, we use diphenyl ether-based epoxy resin (Epoxy Resin 1: manufactured by Nippon Steel Chemical & Material, YSLV-80DE, epoxy equivalent 163, melting point 84°C), epoxy resin synthesized in the synthesis example (Epoxy Resin 2), biphenyl-based epoxy resin (Epoxy Resin 3: manufactured by Mitsubishi Chemical, YX-4000H, epoxy equivalent 193, melting point 105°C), and bisphenol A type epoxy resin (Epoxy Resin 4: manufactured by Nippon Steel Chemical & Material, YD-8125, epoxy equivalent 173). Furthermore, 4,4'-dihydroxybiphenyl (curing agent 1) and dihydroxydiphenyl ether (curing agent 2) are used as difunctional phenolic compounds as curing agents, and biphenyl aralkyl resin (curing agent 3: manufactured by Meiwa Chemicals, MEH-7851, OH equivalent 210, softening point 74°C), phenol aralkyl resin (curing agent 4: manufactured by Mitsui Chemicals, Milex XLC-4L, OH equivalent 182, softening point 65°C), naphthol aralkyl resin (curing agent 5: manufactured by Nippon Steel Chemical & Material, SN-485, OH equivalent 215, softening point 84°C), and phenol novolac (curing agent 6: manufactured by Aica Kogyo, BRG-557, OH equivalent 103, softening point 84°C) are used as polyfunctional phenolic resins. Triphenylphosphine is used as a curing accelerator.

[0055] The components shown in Tables 1 and 2 were blended, thoroughly mixed in a mixer, kneaded with a heated roller for approximately 5 minutes, cooled, and pulverized to obtain epoxy resin compositions for Examples 1-6 and Comparative Examples 1-7, respectively. These epoxy resin compositions were molded at 175°C for 3 minutes, followed by post-curing at 180°C for 4 hours to obtain cured molded products, whose physical properties were evaluated. The results are summarized in Tables 1 and 2. Note that the numbers for each component in Tables 1 and 2 represent parts by weight.

[0056] [evaluation] (1) Coefficient of thermal expansion (coefficient of linear expansion), glass transition temperature Measurements were taken using a Hitachi High-Tech Science TMA7100 thermomechanical measuring device at a heating rate of 10°C / min. (2) High-temperature modulus Dynamic viscoelasticity measurements were performed using a Hitachi High-Tech Science DMA6100 measuring instrument under nitrogen gas flow conditions, frequency of 10 Hz, and heating rate of 2 °C / min. The storage modulus at 260 °C was then read. (3) Thermal conductivity The thermal conductivity was measured using a NETZSCH LFA447 thermal conductivity meter and the xenon flash method. (4) Measurement of melting point and heat of fusion (DSC method) Using a Hitachi High-Tech Science DSC7020 differential scanning calorimetry analyzer, approximately 10 mg of sample was accurately weighed and measured under a nitrogen atmosphere and a heating rate of 10°C / min. (5) Measurement of thermal decomposition temperature and residual carbon percentage Using a Hitachi High-Tech Science TG / DTA7300 thermogravimetric analyzer, the thermal decomposition temperature (10% weight loss temperature) and residual carbon percentage were determined under conditions of nitrogen gas flow and a heating rate of 10°C / min. (6) Water absorption rate A disc with a diameter of 50 mm and a thickness of 3 mm was formed, and after post-curing, it was subjected to moisture absorption for 100 hours under conditions of 85°C and 85% relative humidity. The weight change rate was then measured. (7) Formability The surface condition of the molded test specimens was visually observed, and the moldability was classified based on that condition. ◎; Surface smoothness is good, with no cracks or unfilled areas. ○; Surface smoothness is good, with a few unfilled areas. △; Surface has irregularities and some areas are not filled. ×; Uncured areas remained, resulting in a brittle molded product.

[0057] [Table 1]

[0058] [Table 2]

Claims

1. In an epoxy resin composition comprising epoxy resin and a curing agent, 50 wt% or more of the epoxy resin component is of the following general formula (1): 【Chemistry 1】 (wherein X represents a single bond, -O-, -CO-, -φ-, -O-φ-O-, n represents a number from 0 to 5, and φ represents a phenylene group.) This is a bifunctional epoxy resin represented by the following general formula (2), and 20 to 70 wt% of the curing agent component is 【Chemistry 2】 (wherein Y represents a single bond, -O-, -CO-, -φ-, -O-φ-O-, where φ represents a phenylene group.) A difunctional phenol compound represented by (30 to 80 wt% of the curing agent component is the following general formula (3), 【Transformation 3】 An epoxy resin composition characterized by being a polyfunctional phenolic resin represented as follows: (wherein Z independently represents a hydrocarbon group having 6 to 20 carbon atoms, R1 and R2 independently represent a hydrogen atom or a hydrocarbon group having 1 to 9 carbon atoms, where R1 and R2 include cyclic bodies that are adjacent to each other and linked together, and m represents a number from 0.1 to 15) and forming a crystalline cured product.

2. The epoxy resin composition according to claim 1, wherein the polyfunctional phenolic resin of formula (3) is an aralkyl-type phenolic resin in which Z has a structure containing a benzene skeleton or a naphthalene skeleton, and the hydroxyl group equivalent c is 150 to 350 g / eq.

3. A crystalline cured product obtained by curing the epoxy resin composition according to claim 1 or 2.

4. The cured product according to claim 3, wherein the endothermic peak temperature associated with the melting of the crystal in scanning differential thermal analysis is 170 to 350°C.

5. The cured product according to claim 3 or 4, wherein the heat of fusion in scanning differential thermal analysis is 10 J / g or more in terms of resin components.

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