JP2021195459A - Epoxy resin composition and molding - Google Patents

Abstract

To provide an epoxy resin composition which is excellent in moldability, is high in thermal conductivity when being compounded with an inorganic filler, and gives a molding that is low in thermal expansion and is excellent in heat resistance, humidity resistance and flame retardancy, and a molding using the same.SOLUTION: An epoxy resin composition contains an epoxy resin and a curing agent or an additional inorganic filler as main components, in which an epoxy resin having a 4,4'-bisphenoxy biphenyl structure is used as an epoxy resin component in an amount of 50 wt.% or more, and a bifunctional phenolic compound is used as a curing agent component in an amount of 50 wt.% or more in a curing agent component.SELECTED DRAWING: None

Description

The present invention relates to an epoxy resin composition useful as an insulating material for electrical and electronic materials such as semiconductor encapsulation, laminated plates, and heat dissipation substrates having excellent reliability such as electrical insulation, and a molded product using the same.

Conventionally, as a sealing method for electric and electronic parts such as diodes, transistors, integrated circuits (ICs), semiconductor devices, etc., for example, a sealing method using epoxy resin, silicon resin, etc., glass, metal, ceramic, etc. have been used. The hermetic sealing method has been adopted, but in recent years, resin encapsulation by transfer molding, which is cost-effective and can be mass-produced with improved reliability such as electrical insulation, is the mainstream.

In the resin composition used for resin encapsulation by transfer molding, a encapsulating material composed of an epoxy resin and a resin composition containing a phenol resin as a main component as a curing agent is generally used.

Epoxy resin compositions used for the purpose of protecting devices such as power devices are densely filled with an inorganic filler such as crystalline silica in order to cope with a large amount of heat emitted by the device.

Power devices include those that consist of one chip incorporating IC technology and those that are modularized, and further improvement in heat dissipation, heat resistance, and thermal expansion of the encapsulating material is desired. There is.

In order to meet these demands, attempts have been made to contain inorganic fillers such as crystalline silica, silicon nitride, aluminum nitride, and spherical alumina powder, which have high thermal conductivity, in order to improve the thermal conductivity (patented). Documents 1 and 2). However, if the content of the inorganic filler is increased, the fluidity decreases as the viscosity increases during molding, which causes a problem that 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 of improving the thermal conductivity of the composition by increasing the thermal conductivity of the matrix resin itself is also being studied. For example, Patent Document 3, Patent Document 4, and Patent Document 5 propose a liquid crystal epoxy resin having a rigid mesogen 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 to increasing the filling rate of the inorganic filler, and there is also a problem in terms of electrical insulation. Further, when the aromatic diamine compound was used, although the liquid crystallinity of the cured product could be confirmed, the crystallinity of the cured product was low, and it was not sufficient in terms of high thermal conductivity, low thermal expansion, low hygroscopicity and the like. Furthermore, in order to develop liquid crystallinity, it is necessary to apply a strong magnetic field to orient the molecules, and there are major restrictions on equipment for widespread industrial use. Further, in the compounding system with the inorganic filler, the thermal conductivity of the inorganic filler is overwhelmingly higher than that of the matrix resin, and even if the thermal conductivity of the matrix resin itself is increased, it can be used as a composite material. The reality is that it does not contribute significantly 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 phenoxybiphenylene group, and discloses an epoxy resin composition using isophthalic acid dihydrazide as a curing agent. When such a polyfunctional curing agent is used, the epoxy resin composition is disclosed. Only an amorphous cured product having an amorphous shape was given, and physical properties such as high thermal conductivity and low thermal expansion rate were not improved. So far, there has been no teaching about the physical properties of the cured product obtained from an epoxy resin containing an epoxy resin having a phenoxybiphenylene structure as a main component and a curing agent containing a bifunctional phenol compound as a main component.

Japanese Unexamined Patent Publication No. 11-147936 Japanese Unexamined Patent Publication No. 2002-309067 Japanese Unexamined Patent Publication No. 11-323162 Japanese Unexamined Patent Publication No. 2004-331811 Japanese Unexamined Patent Publication No. 9-118673 U.S. Pat. No. 3219670

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

The present inventors have unique physical properties such as thermal conductivity, heat resistance, and low thermal expansion property when an epoxy resin having a phenoxybiphenylene structure and a specific bifunctional curing agent whose reaction proceeds two-dimensionally are combined. The present invention has been reached by finding that the improvement is achieved.

In the present invention, in an epoxy resin and a curing agent, or an epoxy resin composition containing these and an inorganic filler as main components, 50 wt% or more of the epoxy resin is an epoxy resin having a phenoxybiphenylene structure, and 50 wt% or more of the curing agent. Is an epoxy resin composition characterized by being a bifunctional phenolic compound.

（但し、Ｒ_１、Ｒ_２は水素原子又は、炭素数１〜８の炭化水素基を示し、ｎは１〜５０の数を示す。） The epoxy resin having the phenoxybiphenylene structure is represented by the following formula (1).

(However, R ₁ and R ₂ indicate a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and n indicates a number of 1 to 50.)

Examples of the above bifunctional phenolic compound include hydroquinone, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenylketone, 1,4-bis (4-hydroxyphenoxy) benzene, and the like. Preferred are at least one bifunctional phenolic compound selected from the group consisting of dihydroxydiphenylmethanes, 4,4'-dihydroxydiphenylsulfides and naphthalenediols.

The epoxy resin composition of the present invention may contain an inorganic filler, and in this case, it is preferable that the epoxy resin composition contains 50 to 96 wt% of the inorganic filler. Further, as described later, spherical alumina is preferably mentioned as the inorganic filler.

The epoxy resin composition of the present invention is suitable as an epoxy resin composition for electronic materials, particularly for encapsulants for electronic components or for electrically insulating substrates as described later.

Further, the present invention is a molded product obtained by reacting the above epoxy resin composition and molding and curing.

The cured molded product preferably has a thermal conductivity of 4 W / m · K or more.

The epoxy resin composition of the present invention provides a molded product having excellent reliability such as moldability and electrical insulation, and excellent in high thermal conductivity, low water absorption, low thermal expansion, high heat resistance, and flame retardancy. It is suitably applied as an insulating material for electric and electronic materials such as semiconductor encapsulation, laminated plates, and heat dissipation substrates, and exhibits excellent high heat dissipation, high heat resistance, flame retardancy, and high dimensional stability. The reason why such a specific effect is produced is that an epoxy resin having a rigid structure having a phenoxybiphenylene structure is used as a main component and a bifunctional phenolic compound is used as a main component as a curing agent to form a resin skeleton. It is presumed that the orientation has improved.

Hereinafter, the present invention will be described in detail.

The epoxy resin used in the epoxy resin composition of the present invention contains 50 wt% or more of an epoxy resin having a phenoxybiphenylene structure represented by the above formula (1).

In the formula (1), R ₁ and R ₂ are hydrogen atoms or hydrocarbon groups having 1 to 8 carbon atoms, which may be the same or different from each other, and the hydrocarbon groups include a methyl group and an ethyl group. , Iso-propyl group, tert-butyl group, phenyl group, benzyl group and the like are exemplified, but a hydrogen atom or a methyl group is preferable.

n is a repeat number, representing a number from 0 to 50, but the preferred value of n will vary depending on the application. For example, for applications of semiconductor encapsulants that require a high filling rate of fillers, those having a low viscosity are desirable, and the value of n is 0 to 3, preferably 0.1 to 2, and more preferably n. Those with 0 are contained in an amount of 50 wt% or more. When the epoxy resin of the present invention is a mixture having a different value of n, the number average value of n is 0 to 5, preferably 0.1 to 2, and more preferably 50 wt% or more of the epoxy resin having 0. The number average value of n is 0.1 to 1. These low molecular weight epoxy resins are optionally crystallized and used as solids at room temperature. Further, a high molecular weight epoxy resin is preferably used for applications such as printed wiring boards, and the value of n in this case is 5 to 50, preferably 10 to 40, and more preferably 20 to 40. When the values of n are different, the above range is good as the number average value of n. In this case, if the number average value is 50 or less, a molecule having an n value of 50 or more may be included.

ここで、Ｒ_１及びＲ_２は、上記式（１）のＲ_１及びＲ_２と同じである。 The method for producing the epoxy resin used in the present invention is not particularly limited, but it can be produced by reacting a phenolic compound having a phenoxybiphenylene group of the following formula (2) with epichlorohydrin. This reaction can be carried out in the same manner as a normal epoxidation reaction.

Wherein, _{R 1} and _{R 2} are the same as _{R 1} and _{R 2} in the formula (1).

The reaction between the phenolic compound and epichlorohydrin is, for example, after dissolving the phenolic compound in excess epichlorohydrin, in the presence of an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, preferably at 50 to 150 ° C. , A method of reacting in the range of 60 to 100 ° C. for 1 to 10 hours can be mentioned. The amount of the alkali metal hydroxide used at this time is in the range of 0.8 to 2.0 mol, preferably 0.9 to 1.5 mol, with respect to 1 mol of the hydroxyl group in the phenolic compound. An excess amount of epichlorohydrin is used for the hydroxyl group in the phenolic compound, and usually 1.5 to 15 mol with respect to 1 mol of the hydroxyl group in the phenolic compound. After completion of the reaction, excess epichlorohydrin is distilled off, the residue is dissolved in a solvent such as toluene and methyl isobutyl ketone, filtered, washed with water to remove the inorganic salt, and then the solvent is distilled off to obtain the desired epoxy. Resin can be obtained.

The epoxy resin used in the epoxy resin composition of the present invention can also be synthesized by using a mixture of a phenolic compound having a phenoxybiphenylene group and another phenolic compound having no phenoxybiphenylene group. In this case, the mixing ratio of the phenolic compound having a phenoxybiphenylene group is preferably 50 wt% or more. The other phenolic compounds are not particularly limited, and are selected from those having two or more hydroxyl groups in one molecule.

The epoxy equivalent (g / eq) of the epoxy resin used in the epoxy resin composition of the present invention is usually in the range of 180 to 600, but has low viscosity from the viewpoint of increasing the filling rate and improving the fluidity of the inorganic filler. The ones are good, preferably those in the range of 180 to 300.

As the epoxy resin having a phenoxybiphenylene group, one having crystallinity at room temperature is usually preferably used. The preferred melting point range is 80 ° C to 250 ° C, more preferably 100 ° C to 200 ° C. If it is lower than this, blocking or the like is likely to occur and the handleability as a solid is inferior, and if it is higher than this, compatibility with a curing agent or the like, solubility in a solvent or the like is lowered.

The purity of the epoxy resin having a phenoxybiphenylene group, particularly the amount of hydrolyzable chlorine, should be smaller from the viewpoint of improving the reliability of the electronic component to be applied. Although not particularly limited, it is preferably 1000 ppm or less, more preferably 500 ppm or less. The hydrolyzable chlorine in the present invention means a value measured by the following method. That is, after dissolving 0.5 g of the sample in 30 ml of dioxane, adding 1N-KOH and 10 ml, boiling and refluxing for 30 minutes, cooling to room temperature, further adding 100 ml of 80% acetone water, and potential difference with _{0.002N-AgNO 3 aqueous solution.} It is a value that can be obtained by titration.

In the epoxy resin composition of the present invention, in addition to the epoxy resin having a phenoxybiphenylene group used as an essential component, another epoxy resin having two or more epoxy groups in the molecule may be used in combination as the epoxy resin component. .. For example, bisphenol A, bisphenol F, 3,3', 5,5'-tetramethyl-4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfide, Divalent phenols such as fluorenbisphenol, 2,2'-biphenol, resorcin, catechol, t-butylcatechol, t-butylhydroquinone, allylated bisphenol A, allylated bisphenol F, allylated phenol novolak, or phenol novolak , Bisphenol A novolak, o-cresol novolak, m-cresol novolak, p-cresol novolak, xylenol novolak, poly-p-hydroxystyrene, tris- (4-hydroxyphenyl) methane, 1,1,2,2-tetrakis ( 4-Hydroxyphenyl) ethane, fluoroglycinol, pyrogallol, t-butylpyrogalol, allylated pyrogallol, polyallylated pyrogallol, 1,2,4-benzenetriol, 2,3,4-trihydroxybenzophenone, phenol aralkyl resin, naphthol There are trivalent or higher phenols such as aralkyl resin and dicyclopentadiene resin, and glycidyl etherified products derived from halogenated bisphenols such as tetrabromobisphenol A. One type or two or more types of these epoxy resins can be used.

（但し、Ｚは単結合、メチレン基、ケトン基、酸素原子又は硫黄原子であり、ｒは０〜１の数を示す。） As the epoxy resin other than the epoxy resin having a phenoxybiphenylene group, a bisphenol-based epoxy resin represented by the following formula (3) is preferable.

(However, Z is a single bond, a methylene group, a ketone group, an oxygen atom or a sulfur atom, and r indicates a number of 0 to 1.)

These epoxy resins are made from, for example, hydroquinone, 4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenylketone, and 4,4'-dihydroxydiphenylsulfide as raw materials. It can be synthesized by carrying out a conversion reaction.

The compounding ratio of the epoxy resin having a phenoxybiphenylene group used in the epoxy resin composition of the present invention is 50 wt% or more, preferably 70 wt% or more, and more preferably 80 wt% or more of the total epoxy resin. Further, it is desirable that the total amount of the bifunctional epoxy resin is 70 wt% or more, preferably 80 wt% or more. If it is less than this, the effect of improving physical properties such as thermal conductivity when the cured product is made is small. This is because the higher the content of the epoxy resin having a phenoxybiphenylene group and the higher the content of the bifunctional epoxy resin, the higher the degree of orientation as a molded product.

The bifunctional phenolic compound used as a curing agent has two phenolic hydroxyl groups in one molecule and is not particularly limited, but 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'-dihydroxydiphenylsulfide, 4,4'-dihydroxy Diphenylketone, 4,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxybiphenyl, 2,2'-dihydroxybiphenyl, 10- (2,5-dihydroxyphenyl) -10H-9-oxa-10-phosphafe Nanslen-10-oxide, hydroquinone, resorcin, t-butylhydroquinone, 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 and the like. You may use two or more kinds of these.

Preferred bifunctional phenolic compounds include hydroquinone, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenylketone, 1,4-bis (4-hydroxyphenoxy) benzene, dihydroxy. Examples thereof include one or more phenolic compounds selected from the group consisting of diphenylmethane, 4,4'-dihydroxydiphenylsulfide and naphthalenediol. Here, dihydroxydiphenylmethane and naphthalenediol have a plurality of isomer structures, but any structure may be used, or a mixture of isomers may be used.

Further, as the bifunctional phenolic compound, a compound having a mesogen group is preferably used, specifically, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxy-3,3', 4,4'-. Examples thereof include tetramethylbiphenyl, 4,4'-dihydroxydiphenylketone, 1,5-naphthalenediol, 2,6-naphthalenediol, and 2,7-naphthalenediol. Further, preferred bifunctional phenolic compounds having no mesogen group include hydroquinone, resorcin, 4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenyl ether, and 1,4-bis (4-hydroxyphenoxy). Benzene, 4,4'-dihydroxydiphenyl sulfide can be mentioned.

Here, the mesogen group is a divalent organic group having a rigid structure necessary for exhibiting liquid crystallinity, and an example thereof can be seen in a liquid crystal substance. Examples of the liquid crystal material include Liquid Crystals in Tabellen II, D.I. Demes et al Eds. , VEB Deutscher Verlag fur groundstoffindustrie, Leipzig (1984) can be referred to.

The amount of the bifunctional phenolic compound used as the curing agent is 50 wt% or more, preferably 60 wt% or more, more preferably 70 wt% or more of the total curing agent. If it is less than this, the effect of improving physical properties such as thermal conductivity when the cured product is made 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 the curing agent used in the epoxy resin composition of the present invention, in addition to the above-mentioned bifunctional phenolic compound, other curing agents generally known as curing agents can be used in combination. Examples thereof include amine-based curing agents, acid anhydride-based curing agents, phenol-based curing agents, polypeptide-based curing agents, polyaminoamide-based curing agents, isocyanate-based curing agents, blocked isocyanate-based curing agents, and the like. The blending amount of these other curing agents may be appropriately set in consideration of the type of the curing agent to be blended and the physical properties of the obtained thermally conductive epoxy resin molded product. However, it should not exceed 50 wt% of the total curing agent.

In the epoxy resin composition of the present invention, the compounding ratio of the epoxy resin and the curing agent is preferably in the range of 0.8 to 1.5 in terms of the equivalent ratio of the functional groups in the epoxy group and the curing agent. Outside this range, unreacted epoxy groups or functional groups in the curing agent remain even after curing, and the reliability of the insulating material for electronic components such as electrical insulation is lowered.

It is preferable that the epoxy resin composition of the present invention contains an inorganic filler. In this case, the amount of the inorganic filler added is usually 50 to 96 wt% with respect to the epoxy resin composition, preferably 75 to 96 wt%, and more preferably 85 to 96 wt%. If it is less than this, the effects of high thermal conductivity, low thermal expansion, high heat resistance and the like will not be sufficiently exhibited. These effects are improved as the amount of the inorganic filler added is larger, but they are not improved according to the volume fraction thereof, and are dramatically improved from the time when the amount exceeds a specific amount. These physical properties are due to the effect of controlling the higher-order structure in the polymer state in which the epoxy resin reacts with the curing agent, and this higher-order structure is mainly achieved on the surface of the inorganic filler. It is believed that it requires an amount of inorganic filler. On the other hand, if the amount of the inorganic filler added is larger than this, the viscosity becomes high and the moldability deteriorates.

The inorganic filler is preferably spherical, and is not particularly limited as long as it is spherical, including those having an elliptical cross section, but from the viewpoint of improving fluidity, it should be as close to a true spherical shape as possible. Is particularly preferable. As a result, the inorganic filler can easily form a close-packed structure such as a face-centered cubic structure or a hexagonal close-packed structure in the composition, and a sufficient filling amount can be obtained. In the case of non-spherical shape, as the filling amount increases, the friction between the fillers increases, the fluidity becomes extremely low and the viscosity becomes high before the above upper limit is reached, and the moldability deteriorates.

From the viewpoint of improving the 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, if necessary, an amorphous inorganic filler such as molten silica or crystalline silica may be used in combination regardless of the shape.

Further, the average particle size of the inorganic filler is preferably 30 μm or less. If the average particle size is larger than this, the fluidity of the epoxy resin composition is impaired and the strength is also lowered.

A known curing accelerator can be used in the epoxy resin composition of the present invention. Examples include amines, imidazoles, organic phosphines, Lewis acids and the like, specifically 1,8-diazabicyclo (5,4,0) undecene-7, triethylenediamine, benzyldimethylamine, tri. 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 / ethyltriphenylborate, tetrabutylphosphonium / tetrabutylborate, etc. There are tetraphenylborone salts such as substituted phosphonium / tetra substituted borate, 2-ethyl-4-methylimidazole / tetraphenylporate, N-methylmorpholine / tetraphenylporate. The amount to be added is usually in the range of 0.2 to 10 parts by weight with respect to 100 parts by weight of the epoxy resin. These may be used alone or in combination.

The amount of the curing accelerator added is preferably 0.1 to 10.0 wt% with respect to the total of the epoxy resin and the curing agent. If it is less than 0.1 wt%, the gelation time will be delayed and the workability will be reduced due to the decrease in rigidity during the heating reaction. On the contrary, if it exceeds 10.0 wt%, the reaction will proceed during molding and unfilling will occur. It will be easier.

In the epoxy resin composition of the present invention, in addition to the above components, a mold release agent, a coupling agent, a thermoplastic oligomer, and other substances generally usable for the epoxy resin composition are appropriately blended and used. be able to. For example, a phosphorus-based flame retardant, a flame retardant such as a brom compound or antimony trioxide, a colorant such as carbon black or an organic dye, or the like 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, epoxysilane can be used. The amount of the coupling agent added 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 do not fit well and the moldability deteriorates. On the contrary, if it exceeds 2.0 wt%, the molded product is contaminated due to continuous moldability. Coupling agents are used to improve the adhesive strength between the inorganic filler and the resin component.

Examples of thermoplastic oligomers include C5 and C9 petroleum resins, styrene resins, indene resins, inden / styrene copolymer resins, inden / styrene / phenol copolymer resins, inden / kumaron copolymer resins, and inden / benzothiophene. An example is a copolymer resin. The amount to be added is usually in the range of 2 to 30 parts by weight with respect to 100 parts by weight of the epoxy resin. Thermoplastic oligomers are used to improve the fluidity of the epoxy resin composition during molding and to improve the adhesion to a substrate such as a lead frame.

The epoxy resin composition of the present invention contains an epoxy resin and a curing agent as essential components, and a compounding component (excluding the coupling agent) containing a component such as an inorganic filler is uniformly mixed by a mixer or the like, and then the coupling agent is used. Can be added and kneaded with a heating roll, kneader or the like to produce the product. The order of blending these components is not particularly limited except for the coupling agent. Further, after kneading, the melt-kneaded product can be crushed into a powder or a tablet.

Since the epoxy resin composition of the present invention is particularly excellent for encapsulating electronic components and for heat dissipation substrates, it is suitable as an epoxy resin composition for electronic materials.

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, an epoxy resin composition containing an epoxy resin and a curing agent as main components is dissolved in an organic solvent, impregnated into a sheet-like fiber base material, heated and dried, and the epoxy resin is partially reacted to obtain a prepreg. be able to.

In order to obtain a cured molded product using the epoxy resin composition of the present invention, for example, heat molding methods such as transfer molding, press molding, casting molding, injection molding, extrusion molding, etc. are applied, but mass productivity is applicable. From the viewpoint, transfer molding is preferable.

The epoxy resin composition of the present invention is one of the hydroxyl groups generated by the reaction between the epoxy resin and the curing agent when the epoxy resin and the curing agent are both composed of only bifunctional ones. Since the part further reacts with the epoxy group in the epoxy resin, a three-dimensional cured product is usually given, but in some cases, by using an organic solvent, selecting the curing accelerator type, and controlling the heating reaction conditions such as the reaction temperature, It can be a thermoplastic molded product composed of substantially only a two-dimensional polymer.

The cured molded product of the present invention preferably has crystallinity from the viewpoint of high heat resistance, low thermal expansion and high thermal conductivity. The expression of crystallinity of the molded product can be confirmed by observing the endothermic peak associated with the melting of the crystal as the melting point by scanning differential thermal analysis. The preferred melting point is in the range of 120 ° C to 320 ° C, more preferably in the range of 150 ° C to 300 ° C. The thermal conductivity of the cured molded product is preferably 4 W / m · K or more, and particularly preferably 6 W / m · K or more.

Here, the effect of crystallinity expression 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 (glass-like) molded product having no crystallinity, and its physical properties change significantly with the glass transition point as a boundary. 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, but on the contrary, there is a drawback that the flexibility is lowered and the product becomes brittle. On the other hand, the cured molded product of the present invention is characterized in that it develops crystallinity, but since the change in physical properties is small up to the melting point, the melting point can be used as an index of heat resistance. Since the melting point of the polymer material is higher than the glass transition point, the cured molded product of the present invention can secure high heat resistance while maintaining high flexibility due to the low crosslink density. In addition, the expression of crystallinity means a high intramolecular force, which suppresses the movement of molecules, achieves low thermal expandability, exhibits a high thermal diffusivity, and improves thermal conductivity.

Therefore, the higher the crystallinity of the cured molded product of the present invention, the better. Here, the degree of crystallization can be evaluated from the amount of heat absorbed by the melting of the crystals in the scanning differential thermal analysis. The preferable amount of heat absorption is 10 J / g or more per unit weight of the resin component excluding the filler. It is more preferably 30 J / g or more, and particularly preferably 50 J / g or more. If it is smaller than this, the effect of improving heat resistance, low thermal expansion and thermal conductivity as a molded product is small. The endothermic amount referred to here is the integral of the endothermic peak obtained by measuring with a differential scanning heat analyzer using a sample weighing about 10 mg under the condition of a nitrogen stream and a temperature rise rate of 10 ° C./min. Point to a value. Further, the crystallized cured molded 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 non-crystallized amorphous resin from the total peak area by the total peak area. The desired crystallinity thus determined is 15% or more, more preferably 30% or more, and particularly preferably 50% or more.

The cured molded product of the present invention can be obtained by heating and reacting by the above molding method, but the molding temperature is usually 80 ° C. to 280 ° C., and in order to increase the degree of crystallization of the molded product, molding is performed. It is desirable to react at a temperature lower than the melting point of the product. The preferred molding temperature is in the range of 100 ° C to 220 ° C, more preferably 130 ° C to 200 ° C. The molding time is preferably 30 seconds to 1 hour, more preferably 1 minute to 30 minutes. Further, after molding, the crystallinity can be further increased by post-cure. Normally, the post-cure temperature is 130 ° C to 250 ° C and the time ranges from 1 hour to 20 hours, but at a temperature 5 ° C to 40 ° C lower than the heat absorption peak temperature in differential thermal analysis, 1 hour to 24 hours. It is desirable to apply post-cure.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Reference example 1
50.0 g of p, p'-bis (4-hydroxyphenoxy) biphenyl, 750 g of epichlorohydrin, and 375 g of diethylene glycol dimethyl ether were charged, and 21.5 g of a 48.8% sodium hydroxide aqueous solution was added at 65 ° C. under reduced pressure (about 130 Torr). Dropped over time. During this period, the generated water was removed from the system by azeotropic boiling with epichlorohydrin, and the distilled epichlorohydrin was returned to the inside of the system. After completion of the dropping, the reaction was continued for another 1 hour to dehydrate. Then, epichlorohydrin was removed under reduced pressure, 500 g of diethylene glycol dimethyl ether was added, and then the produced salt was removed by filtration. The diethylene glycol dimethyl ether solution was concentrated by vacuum distillation and then cooled to room temperature, and the precipitated product was recovered and dried to obtain 54 g of a white powdery solid. From the GPC measurement, n = 0 was 94.2% and n = 1 body was 4.1%. The epoxy equivalent was 259 g / eq, and the melting point obtained by the capillary method at a heating rate of 2 ° C./min was 210 ° C. to 215 ° C.

Examples 1-4, Comparative Examples 1-3
As the epoxy resin, the epoxy resin (epoxy resin A) obtained in Reference Example 1, the biphenyl-based epoxy resin (epoxy resin B: manufactured by Mitsubishi Chemical, YX-4000H, epoxy equivalent 193, melting point 105 ° C.), or o-cresol novolac type. An epoxy resin (epoxy resin C: softening point 71 ° C., epoxy equivalent 197) is used.
As a curing agent, 4,4'-dihydroxydiphenyl ether (curing agent A), 4,4'-dihydroxybiphenyl (curing agent B), 4,4'-diaminodiphenyl sulfone (curing agent C), or phenolnovolac (curing agent). D: Aika Kogyo Co., Ltd., BRG-557; OH equivalent 104, softening point 83 ° C., bisphenol content 18.4%) is used. Triphenylphosphine is used as the curing accelerator, and spherical alumina (average particle size 12.2 μm) is used as the inorganic filler.

The components shown in Table 1 were mixed, sufficiently mixed with a mixer, kneaded with a heating roll for about 5 minutes, cooled, and pulverized to obtain the epoxy resin compositions of Examples 1 to 4 and Comparative Examples 1 to 3, respectively. Obtained. After molding with this epoxy resin composition at 170 ° C. for 5 minutes, post-cure was performed at 170 ° C. for 12 hours to obtain a molded product, and its physical characteristics were evaluated. The results are summarized in Table 1. The numbers of each component in Table 1 represent parts by weight.

[evaluation]
(1) Thermal conductivity The thermal conductivity was measured by the transient hot wire method using an LFA447 type thermal conductivity meter manufactured by NETZSCH.
(2) Measurement of melting point and heat of fusion (DSC method)
The measurement was performed at a heating rate of 10 ° C./min using a differential scanning calorimeter (DSC6200 type manufactured by Seiko Instruments Inc.). The endothermic peak temperature was defined as the melting point, and the integral value of the endothermic peak was defined as the heat of fusion.
(3) Linear expansion coefficient, glass transition temperature The linear expansion coefficient and the glass transition temperature were measured at a heating rate of 10 ° C./min using a TMA120C type thermomechanical measuring device manufactured by Seiko Instruments Co., Ltd.
(3) Water absorption rate The epoxy resin composition was formed into a disk having a diameter of 50 mm and a thickness of 3 mm at 170 ° C. for 5 minutes, and after post-cure, was allowed to absorb moisture at 85 ° C. and a relative humidity of 85% for 100 hours. It was used as the later weight change rate.

Claims (5)

In the 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. A characteristic epoxy resin composition.

(However, R ₁ and R ₂ indicate a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and n indicates a number of 1 to 50.) Bifunctional phenolic compounds include hydroquinone, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenylketone, 1,4-bis (4-hydroxyphenoxy) benzene, dihydroxydiphenylmethane, The epoxy resin composition according to claim 1, which is at least one phenolic compound selected from the group consisting of 4,4'-dihydroxydiphenylsulfide and naphthalenediol. The epoxy resin composition according to claim 1 or 2, wherein the epoxy resin composition contains 50 to 96 wt% of an inorganic filler. The epoxy resin composition according to any one of claims 1 to 3, wherein the epoxy resin composition is for an electronic material. A molded product obtained by curing the epoxy resin composition according to any one of claims 1 to 4.