Epoxy resin, its composition and cured product

Abstract

To provide a crystalline epoxy resin that is useful for semiconductor sealing and available as an insulation material for electric and electronic components such as a laminate or a heat radiation substrate, has excellent handleability as a solid at normal temperature, and also excels in low viscosity during molding and solvent solubility, an epoxy resin composition including the same, and a cured product obtained therefrom.SOLUTION: An epoxy resin is represented by general formula (1), and has an epoxy equivalent of 230-350 g / eq and a softening point of 130°C or lower. There are also provided a resin composition including the same and a cured product thereof.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an epoxy resin, an epoxy resin composition, and an epoxy resin cured product. More specifically, the present invention relates to an epoxy resin and an epoxy resin composition which are useful as insulating materials for electric and electronic components such as semiconductor encapsulation, laminates, and heat dissipation substrates and which have excellent handleability as a solid at room temperature, low viscosity during molding, and solvent solubility, and to a cured epoxy resin product obtained by curing the epoxy resin and the epoxy resin composition and which has excellent heat resistance, thermal decomposition stability, and thermal conductivity. [Background technology]

[0002] Epoxy resins have been used industrially for a wide range of applications, and their required performance has become increasingly sophisticated in recent years. In the electrical and electronics fields and power electronics fields, where electronic circuits are becoming increasingly dense and high-frequency, heat generated by electronic circuits is increasing, and the heat dissipation of epoxy resin compositions used in insulating parts has become an issue. Conventionally, this heat dissipation was achieved by the thermal conductivity of the filler, but in order to achieve even higher integration, there is now a demand to improve the thermal conductivity of the epoxy resin matrix itself.

[0003] As an epoxy resin composition having excellent high thermal conductivity, one using an epoxy resin having a mesogenic structure is known. For example, Patent Document 1 discloses an epoxy resin composition containing a biphenol-type epoxy resin and a polyhydric phenol resin curing agent as essential components, and discloses that the composition has excellent stability and strength at high temperatures and can be used in a wide range of fields such as adhesion, casting, sealing, molding, lamination, etc. Patent Document 2 discloses an epoxy compound having two mesogenic structures linked by a bent chain in the molecule. Furthermore, Patent Document 3 discloses a resin composition containing an epoxy compound having a mesogenic group.

[0004] However, such epoxy resins with mesogenic structures have high melting points, and when mixing, the high melting point components are difficult to dissolve and remain undissolved, resulting in problems of reduced curability and heat resistance. Also, high temperatures are required to mix such epoxy resins uniformly with the curing agent. At high temperatures, the curing reaction of the epoxy resin proceeds rapidly and the gelation time is shortened, so the mixing process is severely restricted and handling is difficult. If a third component with good solubility is added to compensate for this drawback, the melting point of the resin decreases and it becomes easier to mix uniformly, but the cured product has a problem of reduced thermal conductivity.

[0005] As a highly thermally conductive resin that can be melt-mixed, Patent Document 4 discloses an epoxy resin obtained by epoxidizing a mixture of hydroquinone and 4,4'-dihydroxybiphenyl, and Patent Document 5 discloses an epoxy resin obtained by epoxidizing a mixture of 4,4'-dihydroxydiphenylmethane and 4,4'-dihydroxybiphenyl. However, these resins have poor solvent solubility and their applications are limited. Patent Document 6 discloses an epoxy resin composition having a diphenyl ether structure, but the curing agent is limited, and general-purpose curing agents such as phenol novolac have insufficient thermal conductivity and heat resistance. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 7-90052 [Patent Document 2] Japanese Patent Application Publication No. 9-118673 [Patent Document 3] Japanese Patent Application Publication No. 11-323162 [Patent Document 4] WO2009 / 110424 [Patent Document 5] JP 2010-43245 A [Patent Document 6] JP 2012-17405 A Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, an object of the present invention is to provide an epoxy resin which overcomes the above problems, is useful as an insulating material for electric and electronic components such as semiconductor encapsulation, laminates, and heat dissipation substrates, has excellent handleability as a solid at room temperature, has low viscosity during molding, and has excellent solvent solubility, and also provides an epoxy resin composition using the same, and a cured product obtained from the same which has excellent high thermal conductivity. [Means for solving the problem]

[0008] As a result of extensive research, the present inventors have found that a specific epoxy resin having a benzonitrile structure is expected to solve the above problems, and that a cured product thereof exhibits effective thermal conductivity and heat resistance.

[0009] That is, the present invention relates to an epoxy resin represented by the following general formula (1), characterized in that the epoxy equivalent is 230 to 350 g / eq and the softening point is 130° C. or lower. [ka] (wherein, X independently represents a direct bond, an oxygen atom, a sulfur atom, -SO2-, -CO-, -COO-, -CONH-, -CH2- or -C(CH3)2-, and n represents a number from 0 to 15.)

[0010] In the above general formula (1), it is preferable that the component where n=0 accounts for 40% or less in area % measured by gel permeation chromatography (GPC area %).

[0011] Furthermore, the present invention relates to an epoxy resin composition comprising the above-mentioned epoxy resin and a curing agent as essential components, and also relates to a cured epoxy resin product obtained by curing this cured epoxy resin product. Effect of the Invention

[0012] The epoxy resin of the present invention has good melt-kneadability at 100° C. or less and excellent solvent solubility, and is therefore suitable for use in epoxy resin compositions and their cured products for applications such as lamination, molding, casting, adhesion, etc. Furthermore, this cured product also has excellent heat resistance, thermal decomposition stability, and thermal conductivity, and is therefore suitable for use as sealing for electric and electronic components, as a circuit board material, etc. [Brief description of the drawings]

[0013] [Figure 1] 1 is a GPC chart of the epoxy resin obtained in Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The present invention will be described in detail below.

[0015] First, the present invention relates to an epoxy resin represented by general formula (1), characterized in that the epoxy equivalent is 230 to 350 g / eq and the softening point is 130° C. or lower. [ka] X independently represents a direct bond, an oxygen atom, a sulfur atom, -SO2-, -CO-, -COO-, -CONH-, -CH2- or -C(CH3)2-, and n represents a number from 0 to 15. From the viewpoint of high thermal conductivity, X is preferably a biphenyl structure which is a direct bond, -SO2-, -CO-, -COO-, or -CONH-, and a biphenyl structure at the 4,4' positions is particularly preferred. On the other hand, from the viewpoint of moldability and solvent solubility, an oxygen atom, a sulfur atom, -CH2-, or -C(CH3)2- is preferred. In this case, as stated above as "independently", the epoxy resin of the formula (1) of the present invention can be a mixture of structures in which X has different structures, and it is possible to adjust high thermal conductivity, moldability, and solvent solubility. In addition, when the X includes a direct bond (biphenyl structure), it is preferable that all of the Xs are not direct bonds from the viewpoint of adjusting high thermal conductivity, moldability, solvent solubility, and the like. When X contains a direct bond, the content thereof is preferably 70% by mass or less, and more preferably 30% by mass to 70% by mass, based on the mass of the raw material compound.

[0016] n is the number of repetitions (number average) and is a number from 0 to 15. It is preferable that the mixture is made of components with different values ​​of n. In addition, the area % measured by gel permeation chromatography (GPC area %) is preferably 40% or less of n=0. More preferably, it is 30% or less. When n=0 is contained in an amount of more than 40%, the crystallinity is strong, the melting point is 130°C or more, and the solvent solubility tends to decrease. In addition, when n is greater than 15, the reactivity is low, and if there are components that remain unreacted during curing, the heat resistance decreases.

[0017] The softening point of the epoxy resin of the present invention is in the range of 130° C. or less. If it is higher than 130° C., the melt-kneadability decreases, and if it has crystallinity, the solvent solubility also decreases. In applications and fields where it is preferable to prevent blocking due to stickiness, such as sealing material applications, it is better for the softening point not to be too low, and in this case, the softening point is preferably 50 to 120° C., more preferably 60 to 110° C.

[0018] The epoxy equivalent of the epoxy resin of the present invention is in the range of 230 to 350. If it is greater than this range, the reactivity is low, and components that remain unreacted during curing are generated, resulting in reduced heat resistance and reliability. If it is less than this range, it indicates that the amount of bifunctional epoxy resin components that do not contain a benzonitrile structure increases, and if there is a large amount of bifunctional crystalline epoxy resin, the solvent solubility and melt-kneadability decrease, and if there is a large amount of bifunctional liquid epoxy resin, the heat resistance and thermal conductivity of the cured product decrease.

[0019] The method for producing the epoxy resin of the present invention is not particularly limited, but it can be produced by reacting a phenolic compound having a benzonitrile structure of the following formula (2) with epichlorohydrin. This reaction can be carried out in the same manner as a general epoxidation reaction. [ka] (wherein, X independently represents a direct bond, an oxygen atom, a sulfur atom, -SO2-, -CO-, -COO-, -CONH-, -CH2- or -C(CH3)2-, and n represents a number from 0 to 15.) The phenolic compound represented by formula (2) has a hydroxyl equivalent (g / eq) of preferably 1150 to 250, more preferably 180 to 230. The melting point is preferably 140°C to 300°C, more preferably 150°C to 280°C.

[0020] Here, the phenolic compound represented by formula (2) is not limited, but can be obtained by a method in which a benzonitrile compound such as 2,4-dichlorobenzonitrile, 2,5-dichlorobenzonitrile, 2,6-dichlorobenzonitrile, 3,5-dichlorobenzonitrile, 2,4-dibromobenzonitrile, 2,5-dibromobenzonitrile, 2,6-dibromobenzonitrile, or 3,5-dibromobenzonitrile is reacted with a dihydroxy compound having the above-mentioned X group, such as 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxybenzophenone, bisphenol A, or bisphenol F, in the presence of a basic catalyst.

[0021] The reaction between the phenolic compound of formula (2) and epichlorohydrin can be, for example, a method in which the phenolic compound is dissolved in excess epichlorohydrin, and then reacted in the presence of an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide at 50 to 150 ° C., preferably 60 to 100 ° C. for 1 to 10 hours. The amount of the alkali metal hydroxide used is 0.8 to 2.0 mol, preferably 0.9 to 1.5 mol, per mol of hydroxyl group in the dihydroxy compound. Epichlorohydrin is used in excess relative to the hydroxyl group in the phenolic compound, usually 1.5 to 15 mol per mol of hydroxyl group in the phenolic compound. After the reaction is completed, the excess epichlorohydrin is distilled off, and the residue is dissolved in a solvent such as toluene or methyl isobutyl ketone, filtered, washed with water to remove inorganic salts, and then the solvent is distilled off to obtain the desired epoxy resin.

[0022] The epoxy resin of the present invention can also be synthesized by using a mixture of a phenolic compound having a benzonitrile structure and another phenolic compound not having a benzonitrile structure. In this case, the mixing ratio of the phenolic compound having a benzonitrile structure is 50 wt% or more. There is no particular restriction on the other phenolic compound, and it is selected from those having two or more hydroxyl groups in one molecule.

[0023] The purity of this epoxy resin having a benzonitrile structure, particularly the amount of hydrolyzable chlorine, should be low from the viewpoint of improving the reliability of electronic components to which it is 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 refers to a value measured by the following method. That is, 0.5 g of a sample is dissolved in 30 ml of dioxane, 10 ml of 1N-KOH is added, and the mixture is boiled and refluxed for 30 minutes, cooled to room temperature, and 100 ml of 80% acetone water is added, and the mixture is subjected to potentiometric titration with 0.002 N-AgNO3 aqueous solution.

[0024] In addition to the epoxy resin having the benzonitrile structure of formula (1) used as an essential component, the epoxy resin composition of the present invention may contain other epoxy resins having two or more epoxy groups in the molecule as epoxy resin components. Examples include bisphenol A, bisphenol F, 3,3',5,5'-tetramethyl-4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl ketone, fluorene bisphenol, 4,4'-biphenol, 3,3',5,5'-tetramethyl-4,4'-dihydroxybiphenyl, 2,2'-biphenol, resorcinol, catechol, t-butyl catechol, etc. 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, 2,4-dihydroxynaphthalene, 2,5-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 2,8-dihydroxy Naphthalene, allyl or polyallyl products of the above dihydroxynaphthalene, dihydric phenols such as allyl bisphenol A, allyl bisphenol F, and allyl phenol novolac, or phenol novolac, bisphenol A novolac, o-cresol novolac, m-cresol novolac, p-cresol novolac, xylenol novolac, poly-p-hydroxystyrene, tris-(4-hydroxyphenyl)methane, 1,1,2,2-tetrakis Examples of the glycidyl ethers include glycidyl ethers derived from trivalent or higher phenols such as (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, and dicyclopentadiene resins, or halogenated bisphenols such as tetrabromobisphenol A.These epoxy resins can be used alone or in combination of two or more.

[0025] The blending ratio of the epoxy resin having the benzonitrile structure of formula (1) used in the epoxy resin composition of the present invention is 50 wt% or more of the total epoxy resin, preferably 70 wt% or more, 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, there is a risk that the effect of improving physical properties such as thermal conductivity when the cured product is formed will be small. This is because the higher the content of the epoxy resin having the benzonitrile structure and the content of the bifunctional epoxy resin, the higher the degree of orientation of the molded product.

[0026] As the curing agent used in the epoxy resin composition of the present invention, any agent generally known as a curing agent for epoxy resins can be used, including dicyandiamide, acid anhydrides, polyhydric phenols, aromatic and aliphatic amines, etc. Among these, in fields requiring high electrical insulation such as semiconductor encapsulants, it is preferable to use polyhydric phenols as a curing agent. Specific examples of the curing agent are shown below.

[0027] Examples of polyhydric phenols include dihydric phenols such as bisphenol A, bisphenol F, bisphenol S, fluorene bisphenol, 4,4'-biphenol, 2,2'-biphenol, hydroquinone, resorcin, and naphthalenediol, and trihydric or higher phenols such as tris-(4-hydroxyphenyl)methane, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, phenol novolac, o-cresol novolac, naphthol novolac, and polyvinylphenol. Further examples include polyhydric phenolic compounds synthesized from dihydric phenols such as phenols, naphthols, bisphenol A, bisphenol F, bisphenol S, fluorene bisphenol, 4,4'-biphenol, 2,2'-biphenol, hydroquinone, resorcin, and naphthalenediol, and condensing agents such as formaldehyde, acetaldehyde, benzaldehyde, p-hydroxybenzaldehyde, and p-xylylene glycol.

[0028] Examples of acid anhydride curing agents include phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylhimic anhydride, dodecynylsuccinic anhydride, nadic anhydride, and trimellitic anhydride.

[0029] Examples of the amine-based curing agent include aromatic amines such as 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylsulfone, m-phenylenediamine, and p-xylylenediamine, and aliphatic amines such as ethylenediamine, hexamethylenediamine, diethylenetriamine, and triethylenetetramine.

[0030] In the above epoxy resin composition, one or a mixture of two or more of these curing agents can be used.

[0031] 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 epoxy group to the functional group in the curing agent. Outside this range, unreacted epoxy groups or functional groups in the curing agent may remain even after curing, which may reduce the reliability of the sealing function.

[0032] In the epoxy resin composition of the present invention, oligomers or polymeric compounds such as polyester, polyamide, polyimide, polyether, polyurethane, petroleum resin, indene resin, indene-coumarone resin, and phenoxy resin may be appropriately blended as other modifiers, etc. The amount of addition is usually within the range of 1 to 30 parts by weight per 100 parts by weight of the total of the resin components.

[0033] The epoxy resin composition of the present invention may contain additives such as inorganic fillers, pigments, flame retardants, thixotropy-imparting agents, coupling agents, flowability improvers, etc. Examples of inorganic fillers include silica powders such as spherical or crushed fused silica and crystalline silica, alumina powders, glass powders, mica, talc, calcium carbonate, alumina, hydrated alumina, etc., and the preferred amount of such fillers used in semiconductor encapsulation is 70% by weight or more, and more preferably 80% by weight or more.

[0034] The pigments include organic or inorganic extender pigments, scaly pigments, etc. The thixotropy-imparting agents include silicone-based, castor oil-based, aliphatic amide wax, oxidized polyethylene wax, organic bentonite-based, etc.

[0035] In the epoxy resin composition of the present invention, a curing accelerator can be used as necessary. Examples include amines, imidazoles, organic phosphines, Lewis acids, etc., specifically, 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-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, and 2-heptadecylimidazole, organic phosphines such as tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine, and phenylphosphine, tetra-substituted phosphonium and tetra-substituted borates such as tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium ethyltriphenylborate, and tetrabutylphosphonium tetrabutylborate, and tetraphenylboron salts such as 2-ethyl-4-methylimidazole tetraphenylborate and N-methylmorpholine tetraphenylborate. The amount added is usually within the range of 0.01 to 5 parts by weight per 100 parts by weight of the total resin components.

[0036] Furthermore, if necessary, the epoxy resin composition of the present invention may contain a release agent such as carnauba wax or OP wax, a coupling agent such as γ-glycidoxypropyltrimethoxysilane, a colorant such as carbon black, a flame retardant such as antimony trioxide, a stress reducing agent such as silicone oil, a lubricant such as calcium stearate, and the like.

[0037] The epoxy resin composition of the present invention can be made into a varnish state by dissolving an organic solvent therein, and then impregnating a fibrous material such as glass cloth, aramid nonwoven fabric, or polyester nonwoven fabric made of liquid crystal polymer or the like, followed by removing the solvent to form a prepreg. In some cases, the composition can be coated on a sheet-like material such as copper foil, stainless steel foil, polyimide film, or polyester film to form a laminate.

[0038] The epoxy resin composition of the present invention can be heat-cured to obtain the resin cured product of the present invention. The cured product can be obtained by molding the epoxy resin composition by a method such as casting, compression molding, or transfer molding. The temperature at this time is usually in the range of 120 to 220°C. EXAMPLES

[0039] The present invention will be specifically described below with reference to examples and comparative examples. However, the present invention is not limited to these. Unless otherwise specified, "parts" refers to parts by weight, and "%" refers to % by weight. In addition, the measurement methods were each as follows.

[0040] 1) Epoxy equivalent A potentiometric titrator was used, and methyl ethyl ketone was used as the solvent. Tetraethylammonium bromide acetate solution was added, and the measurement was performed using a 0.1 mol / L perchloric acid-acetic acid solution in the potentiometric titrator.

[0041] 2)OH equivalent Using a potentiometric titrator, acetylation was carried out with 1.5 mol / L acetyl chloride in 1,4-dioxane as a solvent, and the excess acetyl chloride was decomposed with water and titrated with 0.5 mol / L potassium hydroxide.

[0042] 3) Melting point The DSC peak temperature was determined using a differential scanning calorimeter (EXSTAR6000 DSC / 6200 manufactured by SII NanoTechnology Inc.) at a temperature rise rate of 5°C / min. In other words, this DSC peak temperature was taken as the melting point of the resin.

[0043] 4) Melt Viscosity The viscosity was measured at 150° C. using a Brookfield CAP2000H rotational viscometer.

[0044] 5) Softening point Measured by the ring and ball method according to JIS-K-2207.

[0045] 6) GPC measurement The main body (HLC-8220GPC, Tosoh Corporation) was equipped with columns (TSKgelG4000HXL, TSKgelG3000HXL, TSKgelG2000HXL, Tosoh Corporation) in series, and the column temperature was set to 40°C. Tetrahydrofuran (THF) was used as the eluent, with a flow rate of 1 mL / min, and a refractive index detector was used as the detector. 0.1 g of sample was dissolved in 10 mL of THF and filtered through a microfilter, and 50 μL of the sample was used. Data processing was performed using GPC-8020 model II version 6.00, Tosoh Corporation.

[0046] 7) Glass transition temperature (Tg) The Tg was measured at a heating rate of 10°C / min using a thermomechanical measurement device (EXSTAR6000TMA / 6100 manufactured by SII NanoTechnology Inc.).

[0047] 8) 5% weight loss temperature (Td5), residual coal rate Using a thermogravimetric / differential thermal analyzer (SII NanoTechnology EXSTAR6000TG / DTA6200), the 5% weight loss temperature (Td5) was measured under a nitrogen atmosphere at a heating rate of 10°C / min. The weight loss at 700°C was also measured and calculated as the residual carbon ratio.

[0048] 9) Thermal conductivity The thermal conductivity was measured by the unsteady hot wire method using a NETZSCH LFA447 thermal conductivity meter.

[0049] 10) Melt-mixing ability Melt-kneadability at 100℃ was confirmed. ◯: Kneadable, △: Difficult to knead, ×: Contains unmelted components.

[0050] 11) Solvent solubility 2 g of the resin composition and 2 g of methyl ethyl ketone were weighed out and placed in a sample bottle, and after heating and dissolving, the temperature was gradually lowered in a thermostatic bath, and the temperature in the bath at which the resin precipitated was measured. A precipitation temperature of 25°C or less was rated as ◯, a temperature between 26°C and 60°C was △, and a temperature of 60°C or more was rated as ×.

[0051] Example 1 In a 2L 4-neck separable flask, 54.6g of 4,4'-dihydroxybiphenyl and 29.6g of 4,4'-dihydroxydiphenyl ether were dissolved in 250g of N-methyl-2-pyrrolidone, and then 24.1g of potassium carbonate was added and the mixture was heated to 120°C while stirring under a nitrogen stream. Then, 25.2g of 2,6-dichlorobenzonitrile was added, and the mixture was heated to 145°C and reacted for 6 hours. After neutralizing the reaction liquid with 20.9g of acetic acid, N-methyl-2-pyrrolidone was distilled off under reduced pressure. 250mL of methyl isobutyl ketone was added to the reaction liquid to dissolve the product, and the salt formed was removed by washing with water. Then, methyl isobutyl ketone was removed by distillation under reduced pressure to obtain 84g of hydroxy resin. The hydroxyl equivalent of the obtained hydroxy resin was 195g / eq., the melting point was 235°C, and Mn was 500. Next, 84 g of the obtained hydroxy resin was charged with 800 g of epichlorohydrin and 160 g of diethylene glycol dimethyl ether, and 37.5 g of 48% aqueous sodium hydroxide solution was added dropwise at 65°C under reduced pressure (about 130 Torr) over 3 hours. During this time, the water generated was removed from the system by azeotropy with epichlorohydrin, and the distilled epichlorohydrin was returned to the system. After the dropwise addition was completed, the reaction was continued for another hour to dehydrate. Then, epichlorohydrin was distilled off under reduced pressure, methyl isobutyl ketone was added, and the salt was removed by washing with water, followed by filtration and washing with water, and methyl isobutyl ketone was distilled off under reduced pressure to obtain 105 g of epoxy resin that was solid at room temperature (epoxy resin A). The softening point of the obtained epoxy resin A was 113°C, the epoxy equivalent was 251 g / eq., the melt viscosity was 0.06 Pa·s, and the n=0 content measured by GPC was 30%, and the Mn was 460.

[0052] Example 2 The reaction was carried out in the same manner as in Example 1, except that the amount of 4,4'-dihydroxybiphenyl used was 40.9 g and the amount of 4,4'-dihydroxydiphenyl ether used was 44.4 g, to obtain 112 g of epoxy resin (epoxy resin B). The softening point of the obtained epoxy resin B was 104°C, the epoxy equivalent was 241 g / eq., the melt viscosity was 0.04 Pa s, the content of n=0 as measured by GPC was 23%, and the Mn was 590. The hydroxyl group equivalent of the intermediate hydroxy resin was 184 g / eq., the melting point was 221°C, and the Mn was 670.

[0053] Example 3 The reaction was carried out in the same manner as in Example 1, except that 54.5 g of 4,4'-dihydroxybiphenyl was used, and 29.0 g of dihydroxydiphenylmethane (4,4'-dihydroxydiphenylmethane: 36.2%, 2,4'-dihydroxydiphenylmethane: 46.6%, 2,2'-dihydroxydiphenylmethane: 17.2%) was used instead of 4,4'-dihydroxydiphenylether, to obtain 96 g of epoxy resin. (Epoxy Resin C). The softening point of the obtained epoxy resin C was 120°C, the epoxy equivalent was 264 g / eq., the melt viscosity was 0.06 Pa·s, the n=0 content measured by GPC was 28%, and the Mn was 480. The hydroxyl group equivalent of the intermediate hydroxy resin was 193 g / eq., the melting point was 276°C, and the Mn was 540.

[0054] Example 4 The reaction was carried out in the same manner as in Example 1, except that the amount of 4,4'-dihydroxybiphenyl used was 40.9 g, and 4,4'-dihydroxydiphenyl ether was replaced with 43.6 g of dihydroxydiphenylmethane (4,4'-dihydroxydiphenylmethane: 36.2%, 2,4'-dihydroxydiphenylmethane: 46.6%, 2,2'-dihydroxydiphenylmethane: 17.2%), to obtain 98 g of epoxy resin. (Epoxy Resin D). The softening point of the obtained epoxy resin D was 109°C, the epoxy equivalent was 250 g / eq., the melt viscosity was 0.05 Pa·s, the n=0 content measured by GPC was 29%, and the Mn was 630. The hydroxyl group equivalent of the intermediate hydroxy resin was 205 g / eq., the melting point was 255°C, and the Mn was 540.

[0055] Example 5 The reaction was carried out in the same manner as in Example 1, except that 4,4'-dihydroxybiphenyl was not used and the amount of 4,4'-dihydroxydiphenyl ether used was 88.8 g, to obtain 107 g of epoxy resin (Epoxy Resin E). The softening point of the obtained epoxy resin E was 50°C, the epoxy equivalent was 258 g / eq., the melt viscosity was 0.03 Pa s, the n=0 content measured by GPC was 28%, and the Mn was 540. The hydroxyl group equivalent of the intermediate hydroxy resin was 202 g / eq., the melting point was 157°C, and the Mn was 600.

[0056] Comparative Example 1 The reaction was carried out in the same manner as in Example 1, except that the amount of 4,4'-dihydroxybiphenyl used was 81.8 g, 4,4'-dihydroxydiphenyl ether was not used, and the amount of N-methyl-2-pyrrolidone used was 500 g, to obtain 78 g of epoxy resin. (Epoxy resin F). The obtained epoxy resin F was crystalline, and had a melting point of 139°C, an epoxy equivalent of 226 g / eq., a melt viscosity of 0.10 Pa s, and a content of n=0 as measured by GPC of 34%, and an Mn of 400. The hydroxyl group equivalent of the intermediate hydroxy resin was 220 g / eq., a melting point of 272°C, and an Mn of 500.

[0057] Examples 6 to 10 and Comparative Examples 2 to 4 As the epoxy resin components, epoxy resin A obtained in Example 1, epoxy resin B obtained in Example 2, epoxy resin C obtained in Example 3, epoxy resin D obtained in Example 4, epoxy resin E obtained in Example 5, epoxy resin F obtained in Comparative Example 1, epoxy resin G (4,4'-dihydroxydiphenyl ether type epoxy resin, epoxy equivalent 163g / eq.; YSLV-80XY, manufactured by Nippon Steel Chemical & Material Co., Ltd.) and epoxy resin H (biphenyl type epoxy resin, epoxy equivalent 195g / eq.; YX-4000H, manufactured by Mitsubishi Chemical Co., Ltd.) were used, as the curing agent, phenol novolac resin (OH equivalent 105, softening point 83°C; BRG-557, manufactured by Aica Kogyo Co., Ltd.) was used, and triphenylphosphine was used as the curing accelerator, and an epoxy resin composition was obtained with the formulation shown in Table 1. The results of the melt-kneadability and solvent solubility of the epoxy resin composition are shown in Table 1. The numerical values ​​in the table indicate the weight parts in the formulation. This epoxy resin composition was molded at 175°C and post-cured at 175°C for 5 hours to obtain a cured product test piece, which was then used to measure various physical properties, including Tg, Td5, residual carbon rate, and thermal conductivity.

[0058] [Table 1]

[0059] As is clear from these results, the epoxy resins obtained in the examples have excellent melt-kneadability and solvent solubility, and the cured products thereof have good thermal stability and thermal conductivity, making them suitable for use in power devices and automotive applications.

Claims

1. The epoxy resin is represented by the following general formula (1), and is characterized in that it has an epoxy equivalent of 230 to 350 g / eq and a softening point of 130° C. or lower. 【Chemistry 1】 (X is independently a direct bond, an oxygen atom, a sulfur atom, or -SO 2 -, -CO-, -COO-, -CONH-, -CH 2 - or -C(CH 3 ) 2 -, and n is a number from 0 to 15.)

2. 2. The epoxy resin according to claim 1, wherein the component where n=0 is 40% or less in area % measured by gel permeation chromatography (GPC area %).

3. 3. An epoxy resin composition comprising the epoxy resin according to claim 1 or 2 as an essential component.

4. A cured epoxy resin product obtained by curing the epoxy resin composition according to claim 3.

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