Epoxy resin composition and cured product

Abstract

To provide an epoxy resin composition that yields a cured product with excellent high-temperature properties such as heat resistance, heat transfer rates, and high temperature elastic moduli, and further provide a cured product from the epoxy resin composition.SOLUTION: An epoxy resin composition contains an epoxy resin and a curing agent. The epoxy resin component used here is a polyfunctional epoxy resin with a biphenyl structure. The curing agent component used here is a bifunctional phenolic compound represented by the general formula (2).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, heat dissipation substrate, etc. with excellent reliability, an epoxy resin composition useful as a carbon fiber reinforced composite material, and a cured product using the same.

Background Art

[0002] Conventionally, as a method for encapsulating electrical and electronic components such as diodes, transistors, integrated circuits, etc. 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. However, 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, a sealing material composed of an epoxy resin and a resin composition mainly composed of a phenolic resin as a curing agent is generally used.

[0004] The 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 the 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 discloses that a crystalline cured product can be obtained. However, since it is a reaction between bifunctional components, it has not yet met the current strict requirement characteristics.

Prior Art Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2004-331811 [Patent Document 2] Japanese Patent Publication No. 2012-233206 [Overview of the project] [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 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 polyfunctional epoxy resin and 50 wt% of the curing agent is a difunctional phenol compound, and the present invention relates to a crystalline epoxy resin cured product obtained by curing this composition.

[0010] The above-mentioned polyfunctional epoxy resin is represented by the following formula (1). [ka] (However, X independently represents -CH2-, -CH(Me)-, -CH(φ)-, -CH2-φ-CH2-, -CH(Me)-φ-CH(Me)-, -C(Me)2-φ-C(Me)2-, -CH2-φ-φ-CH2-, -CH(Me)-φ-φ-CH(Me)-, and -C(Me)2-φ-φ-C(Me)2-. Here, Me represents a methyl group, φ represents a phenylene group, and n represents a number from 0 to 10.)

[0011] The above-mentioned difunctional phenol compound is represented by the following formula (2). [ka] (However, Y represents a single bond, -CH2-, -O-, -CO-, or -φ-. Here, φ represents a phenylene group. m represents a number between 0 and 2.)

[0012] Furthermore, the present invention relates to a cured product, particularly a crystalline cured product, that is obtained by curing the above-mentioned epoxy resin composition.

[0013] 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 170°C to 350°C, or the heat of fusion of the crystal (heat of fusion in terms of resin components) in scanning differential thermal analysis is 3 J / g or more. [Effects of the Invention]

[0014] 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, etc., and exhibits excellent high heat dissipation, high heat resistance, and high dimensional stability. The reason for such specific effects is that by reacting a specific polyfunctional epoxy resin with a specific bifunctional phenolic curing agent, mainly the bifunctional component with n = 0 in the polyfunctional epoxy resin represented by the general formula (1) reacts with the bifunctional phenol compound to form a crystalline two-dimensional molecular chain unit having a high melting point and a high elastic modulus at high temperatures, and by introducing a crosslinked structure by using a polyfunctional epoxy resin component, it becomes possible to endow the cured product with high heat resistance, low water absorption, thermal conductivity, low thermal expansion, flame retardancy, etc.

Embodiments for Carrying Out the Invention

[0015] Hereinafter, the present invention will be described in detail.

[0016] 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

[0017] In formula (1), X independently represents -CH2-, -CH(Me)-, -CH(φ)-, -CH2-φ-CH2-, -CH(Me)-φ-CH(Me)-, -C(Me)2-φ-C(Me)2-, -CH2-φ-φ-CH2-, -CH(Me)-φ-φ-CH(Me)-, -C(Me)2-φ-φ-C(Me)2-. From the viewpoints of compatibility with the curing agent and heat resistance, -CH2-, -CH2-φ-CH2-, -CH2-φ-φ-CH2- are preferred.

[0018] n is the number of repetitions and represents a number from 0 to 10. The epoxy resin used in the present invention is a mixture of a plurality of compounds, and the average value of n (Σn / Σ number of molecules) is in the range from 0 to 10. 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 preferred range of n (average value) is 0.1 to 3.0. Also, in order for the cured product to exhibit crystallinity, it is preferable that the component with n = 0 contains 25% or more, preferably 30 wt% or more, and more preferably 40 wt% or more. When the component with n = 0 is less than 25%, the number of polyfunctional components increases, resulting in a high crosslink density in the cured product and inhibition of molecular orientation, thus reducing crystallinity. The molecular weight distribution of the epoxy resin almost reflects the molecular weight distribution of the raw material polyhydric hydroxy resin. As the area ratio of GPC, preferably, the n = 0 form is 25 to 60%, the n = 1 form is 15 to 25%, the n = 2 form is 5 to 15%, and the n ≧ 3 form is 10 to 50%.

[0019] The polyfunctional epoxy resin used in the present invention can be synthesized by reacting a polyhydric hydroxy resin represented by the following general formula (3) with epichlorohydrin. Here, X and n have the same meanings as in formula (1).

Chemical formula

[0020] The polyhydric hydroxy resin of formula (3) preferably has a hydroxyl group (OH) equivalent in the range of 80 to 300 g / eq., more preferably 90 to 200 g / eq., and even more preferably 100 to 150 g / eq. The melting point is preferably in the range of 100 to 300 °C, more preferably in the range of 200 to 250 °C. As the molecular weight distribution, as the area ratio of GPC, preferably, the n = 0 form is 30 to 50%, the n = 1 form is 20 to 30%, the n = 2 form is 10 to 20%, and the n ≧ 3 form is 10 to 35%.

[0021] The polyvalent hydroxy resin of formula (3) can be synthesized by reacting 4,4'-dihydroxybiphenyl with a crosslinking agent such as formaldehyde, acetaldehyde, benzaldehyde, p-xylylene glycol, p-xylylene glycol dimethyl ether, p-xylylenedichloride, p-xylylenedibromide, divinylbenzene, 4,4'-dihydroxymethylbiphenyl, 4,4'-dimethoxymethylbiphenyl, or 4,4'-bischloromethylbiphenyl. In this case, the amount of crosslinking agent used is usually in the range of 0.1 to 0.9 moles per mole of 4,4'-dihydroxybiphenyl, preferably in the range of 0.2 to 0.6 moles. If the amount is smaller than this, the amount of unreacted 4,4'-dihydroxybiphenyl increases, raising the melting point of the epoxy resin and reducing its compatibility with the curing agent. If the amount is larger than this, the viscosity increases and the moldability decreases.

[0022] The epoxy equivalent (g / eq.) of the epoxy resin used in the present invention is usually in the range of 100 to 500, 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 120 to 400 is preferred. More preferably, it is in the range of 130 to 300, and even more preferably in the range of 140 to 200.

[0023] 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, more preferably 70 to 200°C, and even more preferably 100 to 150°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.

[0024] 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. The viscosity of the epoxy resin of the present invention at 150°C is preferably 1000 mPa·s or less, more preferably 500 mPa·s or less, and can also be 50 mPa·s or less.

[0025] 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.

[0026] 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 60 wt% or more, more preferably 70 wt% or more, and even 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.

[0027] In the epoxy resin composition of the present invention, the curing agent contains a difunctional phenol compound represented by the following general formula (2) as an essential component. [ka]

[0028] In formula (2), Y represents a single bond, -CH2-, -O-, -CO-, or -φ-. From the viewpoint of compatibility with epoxy resin, -CH2-, -O-, and -CO- are preferred, while from the viewpoint of heat resistance of the cured product, a single bond and -φ- are preferred. Also, m represents a number from 0 to 2, but is preferably 1 or 2.

[0029] Specific examples of preferred difunctional phenol compounds include 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxybenzophenone, 4,4''-dihydroxy-m-terphenyl, or mixtures thereof.

[0030] The hydroxyl group equivalent of the difunctional phenol compound is preferably in the range of 80 to 200 g / eq., more preferably 80 to 150 g / eq., and even more preferably 80 to 110 g / eq.

[0031] The amount of the difunctional phenol compound used as a curing agent is 50 wt% or more of the total curing agent, preferably 60 wt% or more, and more preferably 70 wt% or more. 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.

[0032] In addition to the difunctional phenol compound of formula (2), 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 should be less than 50 wt%, preferably less than 40 wt%, and more preferably less than 30 wt%, relative to the total amount of curing agent.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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 crystals is 170 to 350°C, preferably 180 to 350°C, and more preferably 200 to 350°C.

[0046] Here, we will briefly explain the effect of crystallinity development in the present invention. 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 develops crystallinity, so there is little change in physical properties up to the melting point, and 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 cured product of the present invention can ensure high heat resistance while maintaining high flexibility with a low crosslinking density. Furthermore, crystallinity development means high intermolecular forces, which suppresses molecular motion, resulting in low thermal expansion and high thermal diffusivity, thus improving thermal conductivity. In addition, the high packing properties of the molecular chains reduce both water vapor permeability and saturated water absorption, improving water resistance.

[0047] Therefore, the higher the degree of crystallinity of the cured product of the present invention, the better. 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 heat of fusion is 3 J / g or more per unit weight of the resin component excluding the filler. More preferably 5 J / g or more, and particularly preferably 10 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 heat of fusion 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.

[0048] The cured product of the present invention can be obtained by heating and reacting it using the molding method described above. Typically, the molding temperature is between 80°C and 350°C, but to increase the crystallinity of the molded product, it is desirable to react it at a temperature lower than the melting point of the molded product. A preferred molding temperature is in the range of 130°C to 280°C, and more preferably 160°C to 250°C. A preferred molding time is 30 seconds to 1 hour, and more preferably 1 minute to 30 minutes. Furthermore, the crystallinity can be further increased by annealing (post-curing) after molding. Typically, the annealing temperature is between 130°C and 250°C, and the time is in the range of 1 hour to 20 hours, but 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 hour to 24 hours. [Examples]

[0049] The present invention will be specifically described below with reference to the following examples.

[0050] Synthesis Example 1 (Polyvalent Hydroxy Resin A) 140 g (0.75 mol) of 4,4'-dihydroxybiphenyl, 600 g of diethylene glycol dimethyl ether, and 3.8 g of p-toluenesulfonic acid were charged into a 1 L separable flask and heated to 90°C. While stirring, 18.3 g (0.225 mol) of 37% formaldehyde was added and the mixture was reacted at 90°C for 1 hour. Then, the temperature was raised to 135°C while distilling off the water, and the reaction was continued for 3 hours. After neutralization with 10% aqueous sodium bicarbonate solution at 90°C, the temperature was raised to 140°C under reduced pressure, and the solvent was removed by distillation to obtain 178 g of solid resin (polyvalent hydroxy resin A). The hydroxyl group equivalent was 100 g / eq., and the melting point was 241°C. The component ratios in general formula (3) obtained from GPC measurements were 49.4% for n=0, 22.8% for n=1, 12.7% for n=2, 7.2% for n=3, 4.4% for n=4, and 3.5% for n≧5.

[0051] Synthesis Example 2 (Polyvalent Hydroxy Resin B) The reaction was carried out in the same manner as in Synthesis Example 1, except that 24.5 g (0.30 mol) of 37% formaldehyde was used, yielding 169 g of solid resin (polyvalent hydroxy resin B). The hydroxyl group equivalent was 103 g / eq., and the melting point was 227 °C. The component ratios in general formula (3) determined by GPC measurement were 39.3% for n=0, 21.8% for n=1, 13.9% for n=2, 9.4% for n=3, 5.9% for n=4, and 9.7% for n≧5.

[0052] Synthesis Example 3 (Polyvalent Hydroxy Resin C) In a 1 L separable flask, 140 g (0.75 mol) of 4,4'-dihydroxybiphenyl, 31.0 g (0.225 mol) of p-xylylene glycol, 3.8 g of p-toluenesulfonic acid, and 300 g of diethylene glycol dimethyl ether were charged. Under a nitrogen stream, the mixture was heated to 150°C while stirring. A solution of 75.3 g (0.30 mol) of 4,4'-bischloromethylbenzene dissolved in 260 g of diethylene glycol dimethyl ether was added dropwise, and the mixture was heated to 130°C and reacted for 2 hours. After the reaction, the mixture was recovered by reprecipitation after being added dropwise to a large amount of pure water, yielding 168 g of a pale yellow crystalline resin (polyvalent hydroxy resin C). The hydroxyl group equivalent of the obtained resin was 125 g / eq. The peak temperature (melting point) measured by DSC was 240.1°C. The component ratios in general formula (3) obtained from GPC measurements were 44.3% for n=0, 25.4% for n=1, 16.1% for n=2, 7.2% for n=3, 4.3% for n=4, and 2.7% for n≧5.

[0053] Synthesis Example 4 (Polyvalent Hydroxy Resin D) 140 g (0.75 mol) of 4,4'-dihydroxybiphenyl and 600 g of diethylene glycol dimethyl ether were charged into a 1 L separable flask. The mixture was heated to 150°C under a nitrogen stream while stirring. A solution of 75.3 g (0.30 mol) of 4,4'-bischloromethylbiphenyl dissolved in 260 g of diethylene glycol dimethyl ether was added dropwise, and the mixture was heated to 170°C and reacted for 2 hours. After the reaction, the mixture was added dropwise to a large amount of pure water and recovered by reprecipitation, yielding 170 g of a pale yellow crystalline resin (polyvalent hydroxy resin D). The hydroxyl group content of the obtained resin was 139 g / eq. The peak temperature (melting point) measured by DSC was 242.4°C. The component ratios in general formula (3) obtained from GPC measurements were 31.2% for n=0, 21.2% for n=1, 13.4% for n=2, 10.6% for n=3, 7.6% for n=4, and 15.4% for n≧5.

[0054] Synthesis Example 5 (Epoxy Resin A) 50 g of polyvalent hydroxy resin A and 690 g of epichlorohydrin were charged, and 40.5 g of 48.8% sodium hydroxide aqueous solution was added dropwise over 3 hours under reduced pressure (approximately 130 Torr) at 60°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, and then the epichlorohydrin was removed by distillation under reduced pressure. Subsequently, 500 mL of toluene was added to dissolve the resin, the salt was removed by filtration, washed with water, and the toluene was removed by distillation to obtain 48.8 g of epoxy resin. This is a biphenyl-based epoxy resin (epoxy resin A) in which X is a methylene bond in general formula (1). The epoxy equivalent was 156 g / eq., the hydrolyzable chlorine content was 280 ppm, the melting point was 143°C, and the viscosity at 150°C was 21 mPa·s. The component ratios in general formula (1) obtained from GPC measurements were 57.0% for n=0, 21.0% for n=1, 7.0% for n=2, 5.3% for n=3, and 9.6% for n≧4.

[0055] Synthesis Example 6 (Epoxy Resin B) The reaction was carried out in the same manner as in Synthesis Example 5, except that 50 g of polyvalent hydroxy resin B, 500 g of epichlorohydrin, and 39.7 g of 48.8% aqueous sodium hydroxide solution were used, yielding 46.2 g of epoxy resin. This is a biphenyl-based epoxy resin (epoxy resin B) in which X in general formula (1) is a methylene bond. The epoxy equivalent was 144 g / eq., the hydrolyzable chlorine was 320 ppm, the melting point was 144 °C, and the viscosity at 150 °C was 34 mPa·s. The component ratios in general formula (1) determined by GPC measurement were 50.0% for n=0, 21.7% for n=1, 7.1% for n=2, 6.8% for n=3, 5.1% for n=4, and 9.3% for n≧5.

[0056] Synthesis Example 7 (Epoxy Resin C) The reaction was carried out in the same manner as in Synthesis Example 5, except that 50 g of polyvalent hydroxy resin C, 400 g of epichlorohydrin, and 32.7 g of 48.8% sodium hydroxide aqueous solution were used, yielding 55.9 g of epoxy resin. This is a biphenyl-based epoxy resin (epoxy resin C) in which X in general formula (1) is a p-xylylene bond. The epoxy equivalent was 174 g / eq., the hydrolyzable chlorine was 260 ppm, the melting point was 142 °C, and the viscosity at 150 °C was 0.42 Pa·s. The component ratios in general formula (1) determined by GPC measurement were 39.4% for n=0, 19.5% for n=1, 11.5% for n=2, 7.8% for n=3, 5.3% for n=4, and 15.6% for n≧5.

[0057] Synthesis Example 8 (Epoxy Resin D) The reaction was carried out in the same manner as in Synthesis Example 5, except that 50 g of polyvalent hydroxy resin D, 350 g of epichlorohydrin, and 29.4 g of 48.8% sodium hydroxide aqueous solution were used, yielding 58.9 g of epoxy resin. This is a biphenyl-based epoxy resin (epoxy resin D) in which X in general formula (1) is a 4,4'-biphenylene bond. The epoxy equivalent was 195 g / eq., the hydrolyzable chlorine was 250 ppm, the melting point was 127 °C, and the viscosity at 150 °C was 0.29 Pa·s. The component ratios in general formula (1) determined by GPC measurement were 28.0% for n=0, 18.4% for n=1, 12.5% ​​for n=2, 8.8% for n=3, 6.4% for n=4, 5.0% for n=5, and 20.9% for n≧5.

[0058] Examples 1-6, Comparative Examples 1-3 As epoxy resins, epoxy resins A to D synthesized in synthesis examples 5 to 8, and a phenol novolac type epoxy resin (epoxy resin E: manufactured by Nippon Steel Chemical & Material, YDPN-638, epoxy equivalent 221) were used. As curing agents, 4,4'-dihydroxydiphenyl ether (curing agent A: Y=-O- in formula (2), hydroxyl group equivalent 101 g / eq.), 4,4'-dihydroxybiphenyl (curing agent B: Y=single bond in formula (2), hydroxyl group equivalent 93 g / eq.), bisphenol A (curing agent C), and phenol novolac (curing agent D: manufactured by Aica Kogyo, BRG-557, OH equivalent 103, softening point 84°C) were used, and triphenylphosphine was used as a curing accelerator.

[0059] The components shown in Table 1 were blended, thoroughly mixed in a mixer, kneaded with a heated roller for approximately 5 minutes, cooled, and pulverized to obtain the epoxy resin compositions of Examples 1-6 and Comparative Examples 1-3, 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 Table 1. Note that the numbers for each component in Table 1 represent parts by weight.

[0060] [evaluation] (1) Coefficient of thermal expansion (coefficient of linear expansion), glass transition temperature (Tg) 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 diffusivity The thermal conductivity was measured using a NETZSCH LFA447 thermal conductivity meter by the xenon flash method. (4) Melting point, 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) Thermal decomposition temperature, residual carbon rate 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.

[0061] [Table 1] (remarks) ND stands for Not Detected.

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】 (However, X is independently -CH ２ -, -CH(Me)-, -CH(φ)-, -CH ２ -φ-CH ２ -, -CH(Me)-φ-CH(Me)-, -C(Me) ２ -φ-C(Me) ２ -, -CH ２ -φ-φ-CH ２ -, -CH(Me)-φ-φ-CH(Me)-, -C(Me) ２ -φ-φ-C(Me) ２ - represents. Here, φ represents a phenylene group, n represents a number from 0 to 10, and the average value of n is from 0.1 to 3.0.) A polyfunctional epoxy resin represented by the following general formula (2), wherein 50 wt% of the curing agent component is the following general formula (2). 【Chemistry 2】 (However, Y is a single bond, -CH ２ (These represent -, -O-, -CO-, and -φ-. Here, φ represents a phenylene group. m represents a number between 0 and 2.) An epoxy resin composition characterized by being a difunctional phenol compound represented by [formula].

2. A cured product obtained by curing the epoxy resin composition of claim 1.

3. A crystalline cured product obtained by curing the epoxy resin composition of claim 1.

4. The cured product according to claim 3, wherein the endothermic peak temperature (melting point) 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 3 J / g or more in terms of resin components.

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