JP2010132766A - Epoxy resin composition and molded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an epoxy resin composition having excellent moldability, high thermal conductivity when compounded with an inorganic filler, and giving a molded product having low thermal expansibility and excellent moisture resistance, and to provide a molded product using the composition. <P>SOLUTION: The epoxy resin composition includes, as main components, an epoxy resin and a curing agent, or together with an inorganic filler, wherein an epoxy resin having a stilbene skeleton is used as an epoxy resin component in an amount of ≥50 wt.% in the epoxy resin component, and a difunctional phenolic compound is used as a curing agent component in an amount of ≥50 wt.% in the curing agent component. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an epoxy resin composition useful as an insulating material for electrical / electronic materials such as semiconductor sealing, laminated board, heat dissipation board and the like having excellent reliability, and a molded article using the same.

  Conventionally, as a sealing method for electrical and electronic parts such as diodes, transistors, and integrated circuits, and semiconductor devices, for example, a sealing method using an epoxy resin or a silicon resin, or a hermetic sealing method using glass, metal, ceramic, or the like has been used. In recent years, resin sealing by transfer molding, which can be mass-produced with improved reliability and cost-effective, has been the mainstream in recent years.

  In a resin composition used for resin sealing by transfer molding, a sealing material composed of an epoxy resin and a resin composition mainly composed of a phenol resin as a curing agent is generally used.

  Epoxy resin compositions used for the purpose of protecting elements such as power devices are filled with an inorganic filler such as crystalline silica at a high density in order to cope with a large amount of heat released from the element.

  As power devices, there are ones constituted by a single chip incorporating IC technology and those made modular, and further improvements in heat dissipation and thermal expansion properties for sealing materials are desired.

  In order to meet these demands, attempts have been made to include inorganic fillers such as crystalline silica, silicon nitride, aluminum nitride, and spherical alumina powder having high thermal conductivity in order to improve thermal conductivity (patents). As Documents 1 and 2) increase the content of the inorganic filler, there is a problem in that the fluidity decreases with increasing viscosity during molding, and the moldability is impaired. Therefore, there is a limit to the method of simply increasing the content of the inorganic filler.

  From the above background, a method for improving the thermal conductivity of the composition by increasing the thermal conductivity of the matrix resin itself has been studied. For example, Patent Literature 3, Patent Literature 4 and Patent Literature 5 propose a liquid crystalline epoxy resin having a rigid mesogenic group and an epoxy resin composition using the same. However, an aromatic diamine compound is used as the curing agent used in these epoxy resin compositions, and there is a limit in increasing the filling rate of the inorganic filler, and there is also a problem in terms of electrical insulation. Further, when an aromatic diamine compound is used, the liquid crystallinity of the cured product can be confirmed, but the crystallinity of the cured product is low, which is not sufficient in terms of high thermal conductivity, low thermal expansion, low hygroscopicity, and the like. Furthermore, in order to exhibit liquid crystallinity, it is necessary to orient the molecules by applying a strong magnetic field, and there are significant restrictions in terms of equipment for wide industrial use. In addition, in the compounding system with the inorganic filler, the thermal conductivity of the inorganic filler is overwhelmingly larger than that of the matrix resin, and even if the thermal conductivity of the matrix resin itself is increased, There is a reality that it does not greatly contribute to the improvement of thermal conductivity, and a sufficient effect of improving thermal conductivity has not been obtained. Patent Document 6 discloses an epoxy resin having a stilbene group, but does not disclose an epoxy resin composition containing a bifunctional phenolic compound as a curing agent, and therefore a cured product obtained therefrom is not disclosed. It does not suggest specific physical properties.

JP-A-11-147936 JP 2002-309067 A JP-A-11-323162 JP-A-2004-331811 JP-A-9-118673 JP-A-9-176144

  Therefore, the object of the present invention is to eliminate the above-mentioned problems, have excellent moldability, high thermal conductivity when combined with an inorganic filler, low thermal expansion, and excellent heat resistance and moisture resistance. It is to provide an epoxy resin composition that gives a product, and further to provide a molded product using the same.

  In the case of combining an epoxy resin having a stilbene group (referring to an epoxy resin having a stilbene skeleton) with a specific bifunctional curing agent in which a reaction proceeds linearly, the thermal conductivity, moisture resistance, The inventors have found that physical properties such as low thermal expansibility are specifically improved and have reached the present invention.

（但し、Ｒ₁、Ｒ₂、Ｒ₃、Ｒ₄は水素原子またはメチル基を示し、ｎは０〜５０の数を示す。） The present invention provides an epoxy resin composition containing an epoxy resin and a curing agent, wherein 50 wt% or more of the epoxy resin is an epoxy resin represented by the following formula (1), and 50 wt% or more of the curing agent is a bifunctional phenolic compound. It is related with the epoxy resin composition which is.

_{(Wherein, R 1, R 2, R} 3, R 4 represents a hydrogen atom or a methyl group, n is a number of 0 to 50.)

  The bifunctional phenolic compound is preferably a phenolic compound having a mesogenic group. Examples of the bifunctional phenolic compound include hydroquinone, 4,4′-dihydroxybiphenyl, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenyl ketone, and 1,4-bis (4-hydroxyphenoxy) benzene. 4,4′-dihydroxydiphenylmethane, 4,4′-dihydroxydiphenyl sulfide, 1,5-naphthalenediol, 2,7-naphthalenediol, and 2,6-naphthalenediol. Compounds.

  The said epoxy resin composition can contain an inorganic filler, and it is good that content is 50 to 98 wt%. In this case, as the inorganic filler, 50% by weight or more of the inorganic filler is preferably spherical alumina.

  The epoxy resin composition of the present invention is suitable as an epoxy resin composition for electronic materials. In addition, the epoxy resin composition of the present invention can be used as a film-like or sheet-like composite material by impregnating the fibrous base material.

  The epoxy resin composition of the present invention can be cured and molded into a cured product or a cured molded product. The heat conductivity of the cured product or cured molded product is preferably 4 W / m · K or more.

  The epoxy resin composition of the present invention provides a cured product or a cured molded product excellent in heat conduction and excellent in moldability, reliability, low water absorption, low thermal expansion, and high heat resistance. This epoxy resin composition is suitably applied as an insulating material for electrical / electronic materials such as semiconductor sealing, laminates, and heat dissipation substrates, and exhibits excellent high heat dissipation and dimensional stability. The reason why such a specific effect occurs is presumed that the orientation of the resin layer is improved by using a conjugated structure of a stilbene group and a bifunctional phenolic compound as a curing agent.

  Hereinafter, the present invention will be described in detail.

  The epoxy resin used for the epoxy resin composition of the present invention is an epoxy resin containing an epoxy resin represented by the above formula (1) (hereinafter also referred to as an epoxy resin of the formula (1) or an epoxy resin having a stilbene group). is there.

In the formula (1), R ₁ , R ₂ , R ₃ and R ₄ are independently a hydrogen atom or a methyl group. Substituents with 2 or more carbon atoms have increased steric hindrance, resulting in reduced reactivity as an epoxy resin, and reduced molecular regularity as a cured product, resulting in improved effects such as thermal conductivity. do not do.

  n is the number of repetitions and represents a number from 0 to 50. In the case of a mixture of a plurality of compounds having different repeating numbers, the average value of n (average n number per molecule) is in the range of 0 to 50. A preferable value of n or an average value thereof varies depending on the application to be applied. For example, for the use of a semiconductor encapsulant that requires a high filling rate of the filler, a material having a low viscosity is desirable, and the value of n or its average value is 0 to 5, preferably 0.1 to 2, Preferably, those having n of 0 are contained in an amount of 50 wt% or more, and the average value of n is 0.1 to 1. A normal epoxy resin is often obtained by a sequential reaction in which a compound having n = 0 is formed and then polymerized to form a compound having n = 1. Epoxy resins can be used advantageously. These low molecular weight epoxy resins are optionally crystallized and used as a solid at room temperature. For applications such as printed wiring boards, high molecular weight epoxy resins are suitably used. In this case, the value of n or the average value thereof is 5 to 50, preferably 10 to 40, more preferably 20 to 20. 40.

The production method of the epoxy resin of the formula (1) is not particularly limited, but a bisphenol compound having a stilbene group represented by the following formula (2) (hereinafter referred to as a bisphenol compound of the formula (2) or a bisphenol having a stilbene group) It is also referred to as a compound.) And epichlorohydrin. This reaction can be performed in the same manner as a normal epoxidation reaction.

In general formula (2), R _1, R ₂ is the same as R _1, R ₂ in the general formula (1) is a hydrogen atom or a methyl group. In the general formula (2), the substitution positions of hydroxyl groups are those in 4,4′-position, 3,4′-position, 3,3′-position, 2,3′-position, and 2,2′-position. However, it is preferably 4,4′-position. Moreover, when using for the raw material of an epoxy resin, the mixture of these isomers may be sufficient. Also, R _3, R ₄ is the same as R _3, R ₄ in the general formula (1) is a hydrogen atom or a methyl group.

  The reaction between the bisphenol compound and epichlorohydrin is, for example, after dissolving the bisphenol compound in excess epichlorohydrin, and then in the presence of an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, preferably at 50 to 150 ° C., The method of making it react for 1 to 10 hours in the range of 60-100 degreeC is mentioned. In this case, the amount of the alkali metal hydroxide used is in the range of 0.8 to 1.2 mol, preferably 0.9 to 1.0 mol, relative to 1 mol of the hydroxyl group in the bisphenol compound. Epichlorohydrin is used in an excess amount with respect to the hydroxyl group in the bisphenol compound, and is usually 1.5 to 15 mol per mol of the hydroxyl group. After completion of the reaction, excess epichlorohydrin is distilled off, the residue is dissolved in a solvent such as toluene, methyl isobutyl ketone, filtered, washed with water to remove inorganic salts, and then the target epoxy is removed by distilling off the solvent. A resin can be obtained.

  The epoxy resin used for the epoxy resin composition of the present invention can also be synthesized using a mixture of the bisphenol compound of formula (2) and another phenolic compound having no stilbene group. In this case, a mixed epoxy resin is synthesized. And content of the epoxy resin of Formula (1) in mixed epoxy resin needs to become 50 wt% or more. In order to synthesize such a mixed epoxy resin, the mixing ratio of the bisphenol compound of the formula (2) in all phenolic compounds needs to be 50 wt% or more. Other phenolic compounds are not particularly limited and are selected from those having two or more hydroxyl groups in one molecule.

  In addition to the epoxy resin of formula (1) used as an essential component, the epoxy resin composition of the present invention may be used in combination with another epoxy resin having two or more epoxy groups in the molecule as an epoxy resin component. .

  The epoxy equivalent of the epoxy resin of the formula (1) used in the epoxy resin composition of the present invention is usually in the range of 150 to 600, but it has a low viscosity from the viewpoint of increasing the filling rate of the inorganic filler and improving the fluidity. The epoxy equivalent is preferably in the range of 160 to 400. Also when using together with other epoxy resins other than the epoxy resin of Formula (1), the epoxy equivalent as a whole epoxy resin has the preferable range of 160 to 400.

  As the epoxy resin of the formula (1), those having crystallinity at normal temperature are preferably used. The range of preferable melting | fusing point is 50 to 250 degreeC, More preferably, it is the range of 60 to 150 degreeC. If it is lower than this, blocking and the like are likely to occur, resulting in poor handling as a solid, and if it is higher than this, compatibility with a curing agent or the like, solubility in a solvent, and the like are reduced. Also when using together with other epoxy resins other than the epoxy resin of Formula (1), it is preferable that melting | fusing point exists in the said range as the whole epoxy resin.

The purity of the epoxy resin of formula (1), in particular the amount of hydrolyzable chlorine, is better from the viewpoint of improving the reliability of the applied electronic component. Although it does not specifically limit, Preferably it is 1000 ppm or less, More preferably, it is 500 ppm or less. In addition, the hydrolyzable chlorine as used in the field of this invention means the value measured by the following method. That is, the potential difference the sample 0.5g were dissolved in dioxane 30 ml, 1N-KOH, after the added boiled under reflux for 30 minutes 10 ml, cooled to room temperature, 80% aqueous acetone 100ml was added, with 0.002 N-AgNO ₃ aqueous solution This is a value obtained by titration. Also when using together with other epoxy resins other than the epoxy resin of Formula (1), it is preferable that it is 1000 ppm or less as a whole epoxy resin. ,

  The compounding ratio of the epoxy resin of the 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, more preferably 90 wt% or more. Furthermore, it is desirable that the total amount of the bifunctional epoxy resin is 90 wt% or more, preferably 95 wt% or more. If it is less than this, the effect of improving physical properties such as thermal conductivity when cured is small. This is because the higher the content of the epoxy resin having a stilbene group and the higher the content of the bifunctional epoxy resin, the higher the degree of orientation as a molded product.

（但し、Ｒ₅、Ｒ₆は、独立して水素原子またはメチル基を示し、Ｚは単結合、メチレン基、酸素原子または硫黄原子、ｒは０または１の数を示す。） As said other epoxy resin used together with the epoxy resin of Formula (1), the bisphenol-type epoxy resin represented by following General formula (3) is preferable.

(However, R ₅ and R ₆ independently represent a hydrogen atom or a methyl group, Z represents a single bond, a methylene group, an oxygen atom or a sulfur atom, and r represents a number of 0 or 1.)

  These epoxy resins include, for example, hydroquinone, 2,5-dimethylhydroquinone, 4,4′-dihydroxybiphenyl, 3,3′-dimethyl-4,4′-dihydroxybiphenyl, 3,3 ′, 5,5′- Tetramethyl-4,4′-dihydroxybiphenyl, 4,4′-dihydroxydiphenylmethane, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenyl ketone, 4,4′-dihydroxydiphenyl sulfide It can be synthesized by performing an epoxidation reaction. You may synthesize these epoxy resins using what was mixed with the bisphenol compound of the said Formula (2) in the raw material stage.

  Examples of the other epoxy resins include bisphenol A, bisphenol F, 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxydiphenylmethane, 4,4′-dihydroxydiphenylsulfone, fluorene bisphenol, Divalent phenols such as 2,2′-biphenol, resorcin, and catechol, or phenol novolak, bisphenol A novolak, o-cresol novolak, m-cresol novolak, p-cresol novolak, xylenol novolak, poly-p-hydroxy Styrene, tris- (4-hydroxyphenyl) methane, 1,1,2,2-tetrakis (4-hydroxyphenyl) ethane, fluoroglycinol, pyrogallol, polyallylated pyrogallol, 1,2,4-benzenetrio , 2,3,4-trihydroxybenzophenone, phenol aralkyl resins, naphthol aralkyl resins, dicyclopentadiene resins and other trihydric phenols or halogenated bisphenols such as tetrabromobisphenol A Examples include glycidyl etherified compounds. These epoxy resins can be used alone or in combination of two or more.

The bifunctional phenolic compound used as a curing agent has two phenolic hydroxyl groups in one molecule. Although not particularly limited, for example, bisphenol A, bisphenol F, 4,4′-dihydroxydiphenylmethane, 4,4′-dihydroxydiphenyl ether, 1,4-bis (4-hydroxyphenoxy) benzene, 1,3-bis (4-hydroxyphenoxy) benzene, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl ketone, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxybiphenyl, 2,2'-dihydroxybiphenyl 10- (2,5-dihydroxyphenyl) -10H-9-oxa-10-phosphaphenanthrene-10-oxide, hydroquinone, resorcin, 1,2-dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 1, 4-dihydroxynaphthalene 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, 1,8-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, etc. Can be mentioned. Two or more of these may be used. Preferably, it is a bifunctional phenolic compound represented by HO—Ar—OH or HO—Ar—X—Ar—OH. Here, Ar represents a phenylene group, and X represents a single bond or a divalent group. As the divalent group, O, CO, phenylene, CH ₂ or S is preferable.

  As the bifunctional phenolic compound used as a curing agent, those having excellent symmetry and small steric hindrance are preferable, and those having a mesogenic group are particularly preferably used. Specifically, 4,4′-dihydroxybiphenyl, 4,4′-dihydroxydiphenyl ketone, 4,4′-dihydroxydiphenyl ester, 1,5-naphthalenediol, 2,6-naphthalenediol, 2,7-naphthalene Examples thereof include diols and bisphenol compounds of the above formula (2). Further, those having no mesogenic group and preferred bifunctional phenolic compounds include hydroquinone, 4,4′-dihydroxydiphenylmethane, 4,4′-dihydroxydiphenyl ether, 1,4-bis (4-hydroxyphenoxy) benzene, Mention may be made of 4,4′-dihydroxydiphenyl sulfide.

  The amount of the bifunctional phenolic compound used as the curing agent is 50 wt% or more of the total curing agent, preferably 70 wt% or more, more preferably 80 wt% or more, and further preferably 90 wt% or more. If it is less than this, the effect of improving physical properties such as thermal conductivity when cured is small. This is because the higher the content of the bifunctional phenolic compound, the higher the degree of orientation as a molded product.

  As a hardening | curing agent used with the epoxy resin composition of this invention, the other hardening agent generally known as a hardening | curing agent other than said bifunctional phenolic compound can be used in combination. Examples include amine curing agents, acid anhydride curing agents, phenolic curing agents, polymercaptan curing agents, polyaminoamide curing agents, isocyanate curing agents, block isocyanate curing agents, and the like. What is necessary is just to set the compounding quantity of these other hardening | curing agents suitably considering the kind of hardening | curing agent to mix | blend and the physical property of the heat conductive epoxy resin molded object obtained. However, it is less than 50 wt% of the total curing agent.

  In the epoxy resin composition of the present invention, the mixing ratio of the epoxy resin and the curing agent is preferably in the range of 0.8 to 1.5 in terms of an equivalent ratio of the epoxy group and the functional group in the curing agent. Outside this range, unreacted epoxy groups or functional groups in the curing agent remain after curing, and the reliability of the insulating material for electronic parts is lowered.

  The epoxy resin composition of the present invention preferably contains an inorganic filler. In this case, the amount of the inorganic filler added is usually 50 to 98 wt% with respect to the epoxy resin composition, preferably 75 to 96 wt%, and more preferably 85 to 96 wt%. By blending the inorganic filler, effects such as high thermal conductivity, low thermal expansion, and high heat resistance are sufficiently exhibited. These effects are improved as the added amount of the inorganic filler is increased, but are not improved in accordance with the volume fraction, and are drastically improved from the point when the added amount exceeds the specific amount. These physical properties are due to the effect of controlling the higher order structure in the polymer state, and since this higher order structure is achieved mainly on the surface of the inorganic filler, a specific amount of inorganic filler is required. It is thought to be. On the other hand, when the addition amount of the inorganic filler is more than 98 wt%, the viscosity becomes high and the moldability is deteriorated.

  The inorganic filler is preferably spherical and is not particularly limited as long as it has a spherical shape including those having a cross section on an ellipse, but from the viewpoint of improving fluidity, it should be as close to a true sphere as possible. Is particularly preferred. Thereby, it is easy to take a close-packed structure such as a face-centered cubic structure or a hexagonal close-packed structure, and a sufficient filling amount can be obtained. When it is not spherical, when the filling amount increases, friction between the fillers increases, and before the addition amount of the inorganic filler becomes sufficient, the fluidity is extremely lowered to increase the viscosity, and the moldability is deteriorated.

  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 more. As such an inorganic filler, alumina, aluminum nitride, crystalline silica and the like are suitable. Among these, spherical alumina is excellent. In addition, an amorphous inorganic filler such as fused silica or crystalline silica may be used in combination, if necessary, regardless of the shape.

  Moreover, it is preferable that the average particle diameter of an inorganic filler is 30 micrometers or less. When the average particle size is large, the fluidity of the epoxy resin composition is impaired and the strength is also lowered.

  A conventionally well-known hardening accelerator can be used for the epoxy resin composition of this invention. Examples include amines, imidazoles, organic phosphines, Lewis acids, etc., specifically 1,8-diazabicyclo (5,4,0) undecene-7, triethylenediamine, benzyldimethylamine, Tertiary amines such as ethanolamine, dimethylaminoethanol, tris (dimethylaminomethyl) phenol, imidazoles such as 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-heptadecylimidazole, Organic phosphines such as tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine, phenylphosphine, tetraphenylphosphonium / tetraphenylborate, tetraphenylphosphonium / ethyltriphenyl Rate, tetra-substituted phosphonium tetra-substituted borate such as tetrabutylphosphonium-tetrabutyl borate, 2-ethyl-4-methylimidazole · tetraphenyl port rate, and the like tetraphenyl boron salts such as N- methylmorpholine-tetraphenyl port rate. These may be used alone or in combination.

  As for the addition amount of the said hardening accelerator, 0.1-10.0 wt% is preferable with respect to the sum total of an epoxy resin and a hardening | curing agent. If it is less than 0.1 wt%, the gelation time will be delayed, resulting in a decrease in workability due to a decrease in rigidity during the heating reaction. Conversely, if it exceeds 10.0 wt%, the reaction will progress during the molding and unfilling will occur. It becomes easy.

  In addition to the above components, the epoxy resin composition of the present invention is appropriately mixed with a mold release agent, a coupling agent, a thermoplastic oligomer, and other components that can be generally used for an epoxy resin composition. Can do. 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.

  Wax can be used as the release agent. As the wax, for example, stearic acid, montanic acid, montanic acid ester, phosphoric acid ester and the like can be used.

  As the coupling agent, for example, epoxy silane can be used. The addition amount of the coupling agent is preferably 0.1 to 2.0 wt% with respect to the epoxy resin composition. If it is less than 0.1 wt%, the resin and the base material will not be well-matched, and the moldability will be poor. The coupling agent is used to improve the adhesion between the inorganic filler and the resin component.

  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, indene / benzothiophene. Examples thereof include copolymer resins. As addition amount, it is the range of 2-30 weight part normally with respect to 100 weight part of epoxy resins. Thermoplastic oligomers are used to improve fluidity during molding of the epoxy resin composition and to improve adhesion to a substrate such as a lead frame.

  The epoxy resin composition of the present invention comprises an epoxy resin and a curing agent as essential components, and a blending component (excluding a coupling agent) containing components such as an inorganic filler is uniformly mixed by a mixer or the like, and then a coupling agent. And knead | mixing with a heating roll, a kneader, etc. can manufacture. There is no restriction | limiting in particular in the mixing | blending order of these components except a coupling agent. Further, after kneading, the melt-kneaded material can be pulverized to be powdered or tableted.

  The epoxy resin composition of the present invention is particularly suitable as an epoxy resin composition for electronic materials because it is excellent for electronic component sealing and heat dissipation substrates. And it is suitable for the use of a semiconductor sealing material.

  The epoxy resin composition of the present invention can be combined with a fibrous base material such as glass fiber to form a composite material. For example, a sheet fiber base material impregnated with an epoxy resin composition mainly composed of an epoxy resin and a curing agent in an organic solvent is impregnated and dried by heating to partially react the epoxy resin to obtain a prepreg. be able to.

  In order to obtain a cured product (cured molded product) using the epoxy resin composition of the present invention, for example, a heat molding method such as transfer molding, press molding, cast molding, injection molding, extrusion molding or the like is applied. From the viewpoint of mass productivity, transfer molding is preferred.

  Even when the epoxy resin composition of the present invention is composed only of a bifunctional epoxy resin and a curing agent, when the epoxy resin and the curing agent are heated and reacted, the epoxy resin and the curing agent react with each other. Since this part further reacts with the epoxy group in the epoxy resin, it usually gives a three-dimensional cured product, but in some cases, by use of an organic solvent, selection of a curing accelerator type, and control of heating reaction conditions such as reaction temperature, It can be set as the thermoplastic molding substantially comprised only by the two-dimensional polymer.

  The cured product of the present invention preferably has crystallinity from the viewpoints of high heat resistance, low thermal expansion and high thermal conductivity. The expression of crystallinity of the cured product can be confirmed by observing an endothermic peak accompanying melting of the crystal as a melting point by scanning differential thermal analysis. A preferred melting point is in the range of 120 ° C. to 280 ° C., more preferably in the range of 150 ° C. to 250 ° C. Moreover, the preferable heat conductivity of hardened | cured material is 4 W / m * K or more, Especially preferably, it is 6 W / m * K or more.

  Here, the effect of crystallinity will be briefly described. Generally, in a cured epoxy resin, a glass transition point is used as an index of heat resistance. This is because a normal epoxy resin cured product is an amorphous (glassy) molded product having no crystallinity, and the physical properties greatly change at the glass transition point. Therefore, in order to increase the heat resistance of the cured epoxy resin, that is, to increase the glass transition point, it is necessary to increase the crosslink density. On the other hand, the cured product of the present invention is characterized in that crystallinity is developed. Since the polymer material has a melting point higher than the glass transition point, the cured product of the present invention can ensure high heat resistance while maintaining high flexibility due to low crosslink density. In addition, the expression of crystallinity means a high intermolecular force, which suppresses the movement of molecules, achieves low thermal expansibility, exhibits high thermal diffusivity, and improves thermal conductivity.

  Therefore, the higher the crystallinity of the cured product of the present invention, the better. Here, the degree of crystallization can be evaluated from the endothermic amount accompanying the melting of the crystal in the scanning differential thermal analysis. A preferable endothermic amount is 10 J / g or more per unit weight of the resin component excluding the filler. More preferably, it is 30 J / g or more, Most preferably, it is 50 J / g or more. When this endothermic amount is small, the effect of improving heat resistance, low thermal expansion and thermal conductivity as a molded product is small. The endothermic amount referred to here refers to the endothermic amount obtained by measuring with a differential scanning calorimeter using a sample accurately weighed about 10 mg in a nitrogen stream under a temperature rising rate of 10 ° C./min. . The crystallized cured product of the present invention can be observed as a clear peak even in wide-angle X-ray diffraction. In this case, the crystallinity can be obtained by dividing the area obtained by subtracting the peak of the amorphous resin that is not crystallized from the entire peak area by the entire peak area. The desired crystallinity thus obtained is 15% or more, more preferably 30% or more, and particularly preferably 50% or more.

  The cured product of the present invention can be obtained by heating reaction with the above molding method. Usually, the molding temperature is 80 ° C. to 250 ° C. In order to increase the crystallinity of the cured molded product, It is desirable to react at a temperature lower than the melting point of the molded product. A preferable molding temperature is in the range of 100 ° C to 200 ° C, more preferably 130 ° C to 180 ° C. The preferable molding time is 30 seconds to 1 hour, more preferably 1 minute to 30 minutes. Further, after molding, the crystallinity can be further increased by post-cure. Usually, the post-cure temperature is 130 ° C. to 250 ° C., and the time is in the range of 1 hour to 20 hours. However, the temperature is 5 ° C. to 40 ° C. lower than the endothermic peak temperature in the differential thermal analysis. It is desirable to perform post-cure.

  Hereinafter, the present invention will be described more specifically with reference to examples.

Reference example 1
100 g of 4,4′-dihydroxy-3,3 ′, 5,5′-tetramethyl-trans-stilbene was dissolved in 700 g of epichlorohydrin and reduced in pressure (about 130 Torr) at 62 ° C. under a 48% aqueous sodium hydroxide solution. 0 g was added dropwise over 3 hours. During this time, the generated water was removed from the system by azeotropy with epichlorohydrin, and the distilled epichlorohydrin was returned to the system. After completion of the dropwise addition, the reaction was further continued for 1 hour for dehydration. Then, epichlorohydrin was distilled off, and 240 g of methyl isobutyl ketone was added, followed by washing with water to remove the salt. Thereafter, 2.4 g of 48% sodium hydroxide was added at 80 ° C. and stirred for 1 hour, and then washed with 400 mL of warm water. Thereafter, 810 g of a 10% sodium phosphate aqueous solution was added for neutralization. Then, after washing repeatedly with water, water was removed by reflux dehydration, and methyl isobutyl ketone was distilled off under reduced pressure to obtain 111 g of milky white crystalline epoxy resin A.

Epoxy equivalent was 203, hydrolyzable chlorine was 420 ppm, melting point by capillary method was 141 ° C. to 146 ° C., and viscosity at 150 ° C. was 19 mPa · s. Here, hydrolyzable chlorine is obtained by dissolving 0.5 g of a sample in 30 ml of dioxane, adding 1 N-KOH, 10 ml, boiling and refluxing for 30 minutes, cooling to room temperature, and further adding 100 ml of 80% acetone water. Is a value measured by performing potentiometric titration with a 0.002N-AgNO ₃ aqueous solution. The melting point is a value obtained by a capillary method at a heating rate of 2 ° C./min. The viscosity was measured with CAP2000H manufactured by BROOKFIELD.

Reference example 2
Reaction was performed in the same manner as in Reference Example 1 using 100 g of 4,4′-dihydroxy-α-methylstilbene and 72.0 g of a 48% aqueous sodium hydroxide solution to obtain 123 g of white crystalline epoxy resin B. The melting point was 132 ° C., the epoxy equivalent was 177, hydrolyzable chlorine was 390 ppm, and the viscosity at 150 ° C. was 8 mPa · s.

Reference example 3
Reaction was carried out in the same manner as in Reference Example 1 using 100 g of 4,4′-dihydroxy-3-tert-butyl-2,3 ′, 5′-trimethyl-trans-stilbene and 53.0 g of 48% aqueous sodium hydroxide. Thus, 108 g of a semisolid epoxy resin C was obtained. Epoxy equivalent was 224, hydrolyzable chlorine was 320 ppm, and viscosity at 150 ° C. was 30 mPa · s.

Examples 1-5, Comparative Examples 1-4
As the epoxy resin, the epoxy resins (epoxy resins A to C) obtained in Reference Examples 1 to 3 are used. 4,4′-dihydroxydiphenylmethane (curing agent A), 4,4′-dihydroxydiphenyl ether (curing agent B), 4,4′-dihydroxybiphenyl (curing agent C), or phenol aralkyl resin (curing agent) D: Mitsui Chemicals, XL-225-LL; OH equivalent 174, softening point 75 ° C.). Triphenylphosphine is used as a curing accelerator, and spherical alumina (average particle size 12.2 μm) is used as an inorganic filler.

  After blending the components shown in Table 1 and thoroughly mixing with a mixer, the mixture kneaded for about 5 minutes with a heating roll was cooled and ground to obtain the epoxy resin compositions of Examples 1 to 5 and Comparative Examples 1 to 4, respectively. Obtained. Using this epoxy resin composition, after molding at 170 ° C. for 5 minutes, a post-cure was performed at 170 ° C. for 12 hours to obtain a cured molded product, and its physical properties were evaluated. The evaluation method is as follows. The results are summarized in Table 1. In addition, the number of each component in Table 1 represents parts by weight.

(1) Thermal conductivity Thermal conductivity was measured by the unsteady hot wire method using an LFA447 type thermal conductivity meter manufactured by NETZSCH.
(2) Linear expansion coefficient and glass transition temperature The linear expansion coefficient and glass transition temperature were measured at a temperature elevation rate of 10 ° C / min using a TMA120C type thermomechanical measuring device manufactured by Seiko Instruments Inc.
(3) Water absorption rate A disk having a diameter of 50 mm and a thickness of 3 mm was formed, and after post-curing, the weight change rate after absorbing for 100 hours under the conditions of 85 ° C. and relative humidity of 85% was used.

Claims (8)

In an epoxy resin composition containing an epoxy resin and a curing agent, 50 wt% or more of the epoxy resin is an epoxy resin represented by the following formula (1), and 50 wt% or more of the curing agent is a bifunctional phenolic compound. An epoxy resin composition.

_{(Wherein, R 1, R 2, R} 3, R 4 represents a hydrogen atom or a methyl group, n is a number of 0 to 50.)   The epoxy resin composition according to claim 1, wherein the bifunctional phenolic compound is a phenolic compound having a mesogenic group.   Bifunctional phenolic compounds are hydroquinone, 4,4′-dihydroxybiphenyl, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenyl ketone, 1,4-bis (4-hydroxyphenoxy) benzene, 4,4 ′ -At least one phenolic compound selected from the group consisting of -dihydroxydiphenylmethane, 4,4'-dihydroxydiphenyl sulfide, 1,5-naphthalenediol, 2,7-naphthalenediol, and 2,6-naphthalenediol. 3. The epoxy resin composition according to 1 or 2.   The epoxy resin composition according to any one of claims 1 to 3, comprising 50 to 98 wt% of an inorganic filler.   The epoxy resin composition according to claim 4, wherein 50 wt% or more of the inorganic filler is spherical alumina.   It is an epoxy resin composition for electronic materials, The epoxy resin composition in any one of Claims 1-5 characterized by the above-mentioned.   Hardened | cured material obtained by hardening the epoxy resin composition in any one of Claims 1-6.   The cured product according to claim 7, which has a thermal conductivity of 4 W / m · K or more.