JP7320942B2 - Epoxy resin, epoxy resin composition and cured product - Google Patents

Description

INDUSTRIAL APPLICABILITY The present invention is useful as an insulating material for electrical and electronic parts such as highly reliable semiconductor encapsulation, laminates, and heat dissipating substrates. The present invention relates to an epoxy resin having excellent properties, an epoxy resin composition using the same, and a cured product obtained therefrom having excellent high thermal conductivity.

Epoxy resins have been used in a wide range of industrial applications, and their required performance has become increasingly sophisticated in recent years. In the electric/electronics field and the power electronics field, where electronic circuits are becoming more dense and higher in frequency, the amount of heat generated from electronic circuits is increasing. It's becoming Conventionally, this heat dissipation has been covered by the thermal conductivity of the filler, but in order to achieve higher integration, it has become necessary to improve the thermal conductivity of the matrix epoxy resin itself.

As an epoxy resin composition excellent in high thermal conductivity, one using an epoxy resin having a mesogenic structure is known. It discloses an epoxy resin composition as a component, which is excellent in stability and strength at high temperatures and can be used in a wide range of fields such as adhesion, casting, sealing, molding and lamination. Further, Patent Document 2 discloses an epoxy compound having two mesogenic structures linked by a bent chain in its molecule. Furthermore, Patent Document 3 discloses a resin composition containing an epoxy compound having a mesogenic group.

However, such an epoxy resin having a mesogenic structure has a high melting point, and when a mixing treatment is performed, the high melting point component is difficult to dissolve and remains undissolved, resulting in a problem of reduced curability and heat resistance. Also, a high temperature was required to uniformly mix such an epoxy resin with a curing agent. At high temperatures, the curing reaction of the epoxy resin proceeds rapidly and the gelling time is shortened. When a soluble third component is added to compensate for this drawback, the melting point of the resin is lowered to facilitate uniform mixing, but the resulting cured product has a reduced thermal conductivity.

As a high thermal conductivity 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 4,4'-dihydroxy Epoxy resins are disclosed which are epoxidized mixtures of diphenylmethane and 4,4'-dihydroxybiphenyl. However, these resins are poorly soluble in solvents and have limited applications.

JP-A-7-90052 JP-A-9-118673 JP-A-11-323162 WO2009/110424 JP 2010-43245 A

Accordingly, an object of the present invention is to solve the above problems, and to provide excellent handleability as a solid at normal temperature, which is useful as an insulating material for electric and electronic parts such as highly reliable semiconductor encapsulation, laminates, and heat dissipation substrates. The object of the present invention is to provide a crystalline modified epoxy resin having low viscosity during molding and excellent solvent solubility, an epoxy resin composition using the same, and a cured product obtained therefrom having excellent high thermal conductivity.

Through intensive studies, the present inventors have found that the above problems are expected to be solved by reacting a mixture of compounds having a specific phenolic hydroxyl group with epichlorohydrin, and that the cured product has thermal conductivity. It was discovered that the effect was expressed.

（式中、Ｇはグリシジル基を示し、ビフェニル環に結合するグリシジルエーテル基は４，４’結合であるか２，２’結合であり、ｎは０～１０の数を示す。） That is, the present invention provides an epoxy resin represented by the following general formula (1), wherein the total amount of n = 0 compounds is 90 wt% or less, and the content of n = 1 or more compounds is 5 wt% to 35 wt%. It is an epoxy resin characterized by

(In the formula, G represents a glycidyl group, the glycidyl ether group bonded to the biphenyl ring is a 4,4′ bond or a 2,2′ bond, and n represents a number from 0 to 10.)

The present invention is an epoxy resin obtained by reacting a mixture containing 4,4'-dihydroxybiphenyl and 2,2'-dihydroxybiphenyl as monomers with epichlorohydrin and represented by the general formula (1). , the total of all n = 0 form derived from each monomer is 90 wt% or less, and all n = 1 or more compounds derived from each monomer containing a copolymer structure are 5 to The epoxy resin of claim 1, which is 35 wt%.
The present invention is obtained by reacting a mixture obtained by mixing 0.1 to 10 parts by weight of 2,2'-dihydroxybiphenyl with 1 part by weight of 4,4'-dihydroxybiphenyl with epichlorohydrin, and having an epoxy equivalent of 130 to 130 parts by weight. 190 range.

The present invention also relates to an epoxy resin composition comprising an epoxy resin and a curing agent, which is characterized by containing the above-mentioned epoxy resin as an essential component as part or all of the epoxy resin.

Furthermore, the present invention relates to a resin cured product obtained by curing the above resin composition.

INDUSTRIAL APPLICABILITY The epoxy resin and epoxy resin composition of the present invention are excellent in solvent solubility, moldability and reliability, and exhibit excellent high thermal conductivity in cured products. In addition, by suppressing the crystallinity, the yield is improved, which is advantageous in terms of production. The reason why such a specific effect occurs is that epoxidation in the coexistence of 4,4'-dihydroxybiphenyl and its isomer 2,2'-dihydroxybiphenyl results in the relaxation of the crystallinity of the resin itself. It is presumed that both the improvement of the solvent solubility of and the maintenance of the orientation that contributes to the thermal conductivity were achieved.

1 is a GPC chart of Modified Epoxy Resin A (Example 1).

The present invention will be described in detail below.

The epoxy resin of the present invention is an epoxy resin represented by the above general formula (1), wherein the total amount of n = 0 compounds is 90 wt% or less, and the content of n = 1 or more compounds is 5 wt% to 35 wt%. be.
In formula (1), the glycidyl ether groups bonded to the biphenyl ring are either 4,4′ bonds or 2,2′ bonds, and both 4,4′ and 2,2′ bonds coexist. n = 1 or more compounds are homopolymers derived from 4,4'-dihydroxybiphenyl, homopolymers derived from 2,2'-dihydroxybiphenyl, and further 4,4'-dihydroxybiphenyl and 2,2'-dihydroxy A mixture containing a copolymer that is a co-reactive structure with biphenyl.
n represents a number from 0 to 10, and the average value (number average) ranges from 0.1 to 5, preferably from 0.1 to 2.

The modified epoxy resin of the present invention can be produced by reacting a mixture of 4,4'-dihydroxybiphenyl and 2,2'-dihydroxybiphenyl with epichlorohydrin. This reaction can be carried out in the same manner as a normal epoxidation reaction. The epoxy resin of the present invention contains epoxidized 4,4'-dihydroxybiphenyl and epoxidized 2,2'-dihydroxybiphenyl, and also contains 4,4'-dihydroxybiphenyl and 2,2'-dihydroxy in one molecule. It is a mixture containing epoxidized products having units derived from biphenyl. Epoxidized products obtained by reacting a dihydroxy compound with epichlorohydrin include epoxidized products with a degree of polymerization of 0 (n=0), as well as multimers such as n=1 (di-isomer) and n=2 (tri-isomer). included.

In the epoxy resin of the present invention, the total of all n=0 forms derived from 4,4'-dihydroxybiphenyl and 2,2'-dihydroxybiphenyl structures is 90 wt% or less. If it exceeds this range, there is a possibility that the crystallinity derived from the 4,4'-dihydroxybiphenyl structure and the high melting point may prevent molding. On the other hand, the lower limit of the total amount of n=0 is preferably 50 wt % or more, more preferably 70 wt % or more. If the amount is less than this, the crystallinity is lowered, and there is a possibility that the thermal conductivity is lowered.
In addition, n=1 or more compounds containing co-reactive structures are 5 wt % to 35 wt %, preferably 10 wt % to 30 wt %. If the amount is less than this range, the melting point and crystallinity may not be lowered, and molding may not be possible. Here, the co-reacted structure is a random reaction of the 4,4'- and 2,2'-isomers. It becomes an epoxy resin with each. By including the epoxy resin with this co-reactive structure, the resin has different characteristics from those obtained by simply mixing single-structure epoxy resins composed of respective monomers.

The mixing ratio of 4,4′-dihydroxybiphenyl and 2,2′-dihydroxybiphenyl is in the range of 2,2′-dihydroxybiphenyl/4,4′-dihydroxybiphenyl=0.1 to 10.0 by weight. is preferably in the range of 0.2 to 5.0, more preferably in the range of 0.3 to 3.0. If it is smaller than this, the handleability will be inferior due to the high melting point of the epoxy compound of 4,4'-dihydroxybiphenyl.
Since the structural ratio of the resulting modified epoxy resin is almost the same as the charging ratio, the scope of the epoxy resin is also the same. That is, it is derived from 2,2'-dihydroxybiphenyl, and the glycidyl ether group bonded to the biphenyl ring becomes a 2,2' bond derived from the 2,2'-position structure and 4,4'-dihydroxybiphenyl, The 4,4′-position structure is a glycidyl ether group that binds to the biphenyl ring to form a 4,4′ bond, and the existing molar ratio of the 2,2′-position structure/4,4′-position structure is the above range. Isomeric structures other than 4,4' and 2,2' may be contained, but are preferably 10 mol% or less.

A mixture of 4,4'-dihydroxybiphenyl and 2,2'-dihydroxybiphenyl (hereinafter referred to as a phenol mixture) is reacted with epichlorohydrin to obtain the epoxy resin of the present invention. In the reaction with epichlorohydrin, for example, a phenol mixture is dissolved in an excess amount of epichlorohydrin in terms of molar ratio with respect to these phenolic hydroxyl groups, and then in the presence of an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide. , 50 to 150° C., preferably 60 to 100° C., for 1 to 10 hours. In this case, the alkali metal hydroxide is used in an amount of 0.8 to 1.2 mol, preferably 0.9 to 1.1 mol, per 1 mol of hydroxyl group in the phenol mixture. Epichlorohydrin is used in an excess amount relative to the hydroxyl groups in the phenol mixture, usually 1.5 to 15 mol, preferably 3 to 10 mol, per 1 mol of hydroxyl groups in the phenol mixture. After completion of the reaction, excess epichlorohydrin is distilled off, the residue is dissolved in a solvent such as toluene or methyl isobutyl ketone, filtered, washed with water to remove inorganic salts, and the solvent is distilled off to obtain the desired epoxy. resin can be obtained.

In the production of the epoxy resin of the present invention, a different phenolic compound other than the phenolic compounds of 4,4'-dihydroxybiphenyl and 2,2'-dihydroxybiphenyl may be added to the phenol mixture as long as the effect of the present invention is not impaired. A small amount can be mixed. However, in this case, the total amount of the different phenolic compounds should be 50 wt% or less, preferably 30 wt% or less, more preferably 10 wt% or less, of the total phenolic compounds.

The epoxy equivalent weight of the epoxy resin of the present invention is usually in the range of 130-190. In order to improve the thermal conductivity of the cured product, it is effective to highly fill the composition with an inorganic filler. On the other hand, when the content of the epoxide of 4,4'-dihydroxybiphenyl is large, an effect on thermal conductivity can be expected. Considering the case of mixing a small amount of a different phenolic compound other than the 4,4'-dihydroxybiphenyl and 2,2'-dihydroxybiphenyl phenolic compounds in order to control the fluidity, etc., the epoxy equivalent is 140 to 170. A range is more preferred.

The epoxy resin of the present invention has crystallinity at room temperature. The development of crystallinity can be confirmed as an endothermic peak accompanying crystal melting in differential scanning calorimetry. In this case, since the modified epoxy resin of the present invention is a mixture, the endothermic peak in this case is generally observed not as one but as a plurality of peaks. The melting point observed by differential scanning calorimetry is an endothermic peak derived from a modified epoxy resin derived from 4,4'-dihydroxybiphenyl and 2,2'-dihydroxybiphenyl, and the lowest endothermic peak at 50°C. °C or higher, preferably 70 °C or higher, and the highest endothermic peak is 150 °C or lower, preferably 130 °C or lower. If it is lower than this, blocking occurs when it is made into a powder, and the handleability as a solid at room temperature is lowered. Further, the melt viscosity at 150° C. is preferably as low as possible, and is usually 0.1 Pa·s or less, preferably 0.01 Pa·s or less.

The purity of the modified epoxy resin of the present invention, particularly the amount of hydrolyzable chlorine, should be less than the viewpoint of improving the reliability of electronic parts to which it is applied. Although not particularly limited, it is preferably 1000 ppm or less, more preferably 500 ppm or less. In addition, the hydrolyzable chlorine referred to in the present invention refers to the value measured by the following method. That is, after dissolving 0.5 g of the sample in 30 ml of dioxane, add 10 ml of 1N-KOH, boil and reflux for 30 minutes, cool to room temperature, add 100 ml of 80% acetone water, and perform potentiometric titration with 0.002N-AgNO aqueous solution. is the value obtained by

The epoxy resin composition comprising the epoxy resin and the curing agent of the present invention is an epoxy resin composition characterized by containing the above modified epoxy resin as an essential component as part or all of the epoxy resin. 70 wt % or more, more preferably 90 wt % or more of the total epoxy resin is the modified epoxy resin. If the proportion of the modified epoxy resin used is less than this, the effect of improving the thermal conductivity of the cured product will be small.

In the epoxy resin composition of the present invention, other ordinary epoxy resins having two or more epoxy groups in the molecule may be used in combination with the above epoxy resins used as essential components of the present invention. Examples include bisphenol A, bisphenol F, 3,3′,5,5′-tetramethyl-4,4′-dihydroxydiphenylmethane, 4,4′-dihydroxydiphenylsulfone, 4,4′-dihydroxy diphenyl sulfide, 4,4'-dihydroxydiphenyl ketone, fluorene bisphenol, 4,4'-biphenol, 3,3',5,5'-tetramethyl-4,4'-dihydroxybiphenyl, zorcin, catechol, hydroquinone, t -butylcatechol, 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-dihydroxynaphthalene, Dihydric phenols such as allylated or polyallylated dihydroxynaphthalene, 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 novolac, poly-p-hydroxystyrene, tris-(4-hydroxyphenyl)methane, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, fluoroglycinol, pyrogallol, t -Butylpyrogallol, allylated pyrogallol, polyallylated pyrogallol, 1,2,4-benzenetriol, 2,3,4-trihydroxybenzophenone, phenol aralkyl resin, naphthol aralkyl resin, dicyclopentadiene resin, etc. phenols; or halogenated bisphenols such as tetrabromobisphenol A; These epoxy resins can be used singly or in combination of two or more.

As the curing agent used in the epoxy resin composition of the present invention, all those generally known as curing agents for epoxy resins can be used, including dicyandiamide, acid anhydrides, polyhydric phenols, aromatic and aliphatic amines. etc. Among these, polyhydric phenols are preferably used as a curing agent in fields such as semiconductor encapsulants that require high electrical insulation. Specific examples of the curing agent are shown below.

Examples of polyhydric phenols include dihydric phenols such as bisphenol A, bisphenol F, bisphenol S, fluorene bisphenol, 4,4'-biphenol, 2,2'-biphenol, hydroquinone, resorcinol, and naphthalenediol; , tris-(4-hydroxyphenyl)methane, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, phenol novolak, o-cresol novolak, naphthol novolak, polyvinylphenol, etc. There are phenols. Furthermore, dihydric phenols such as phenols, naphthols, bisphenol A, bisphenol F, bisphenol S, fluorene bisphenol, 4,4'-biphenol, 2,2'-biphenol, hydroquinone, resorcinol, and naphthalenediol, There are polyhydric phenolic compounds synthesized with condensing agents such as formaldehyde, acetaldehyde, benzaldehyde, p-hydroxybenzaldehyde and p-xylylene glycol.

Examples of acid anhydride curing agents include phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyl himic anhydride, dodecynylsuccinic anhydride, nadic anhydride, and trimellitic anhydride.

Amine-based curing agents include aromatic amines such as 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylsulfone, m-phenylenediamine, and p-xylylenediamine; Alternatively, there are aliphatic amines such as ethylenediamine, hexamethylenediamine, diethylenetriamine and triethylenetetramine.

One or a mixture of two or more of these curing agents can be used in the epoxy resin composition.

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 the equivalent ratio of the epoxy groups to the functional groups in 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 sealing function is lowered, which is not preferable.

In the resin composition of the present invention, oligomers or polymer compounds such as polyester, polyamide, polyimide, polyether, polyurethane, petroleum resin, indene resin, indene-cumarone resin, phenoxy resin, etc. May be blended. The amount added is usually in the range of 1 to 30 parts by weight with respect to 100 parts by weight of the total resin components.

Additives such as inorganic fillers, pigments, flame retardants, thixotropic agents, coupling agents, fluidity improvers and the like can be added to the resin composition of the present invention. Examples of inorganic fillers include thermally conductive fillers such as spherical or crushed fused silica, silica powder such as crystalline silica, alumina powder, glass powder, mica, talc, calcium carbonate, alumina, and hydrated alumina. When used in a semiconductor encapsulant, the compounding amount is preferably 70% by weight or more, more preferably 80% by weight or more.

Pigments include organic or inorganic extender pigments, scaly pigments, and the like. Examples of the thixotropic agent include silicon-based, castor oil-based, aliphatic amide wax, oxidized polyethylene wax, and organic bentonite-based agents.

Furthermore, a curing accelerator can be used in the epoxy resin composition of the present invention, if necessary. Examples include amines, imidazoles, organic phosphines, Lewis acids, etc. Specific examples include 1,8-diazabicyclo(5,4,0)undecene-7, triethylenediamine, benzyldimethylamine, tri Amines such as ethanolamine, dimethylaminoethanol, tris(dimethylaminomethyl)phenol; alternatively, 2-methylimidazole, 2-phenylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, 2 - imidazoles such as heptadecylimidazole; or organic phosphines such as tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine, phenylphosphine; or tetraphenylphosphonium-tetraphenylborate, tetraphenylphosphonium-ethyl. Triphenylborate, tetrasubstituted phosphonium/tetrasubstituted borate such as tetrabutylphosphonium/tetrabutylborate, 2-ethyl-4-methylimidazole/tetraphenylborate, N-methylmorpholine/tetraphenylborate such as tetraphenylborate, etc. Lewis acid; The amount added is usually in the range of 0.01 to 5 parts by weight per 100 parts by weight of the total resin components.

Further, if necessary, the resin composition of the present invention may contain release agents such as carnauba wax and OP wax, coupling agents such as γ-glycidoxypropyltrimethoxysilane, colorants such as carbon black, and trioxide. Flame retardants such as antimony, stress reducing agents such as silicone oil, lubricants such as calcium stearate, and the like can be used.

The resin composition of the present invention is made into a varnish state by dissolving an organic solvent, impregnated with a fibrous material such as a glass cloth, an aramid nonwoven fabric, a polyester nonwoven fabric such as a liquid crystal polymer, and the like, and then the solvent is removed to form a prepreg. can do. In some cases, a laminate can be obtained by coating a sheet-like material such as a copper foil, a stainless steel foil, a polyimide film, a polyester film, or the like.

A cured resin product of the present invention can be obtained by heat-curing the resin composition of the present invention. This 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.

The present invention will be specifically described below with reference to Synthesis Examples, Examples and Comparative Examples. However, the present invention is not limited to these. "Parts" means parts by weight and "%" means % by weight unless otherwise specified. Moreover, the measurement method was each measured by the following methods.

1) Epoxy equivalent Using a potentiometric titrator, using methyl ethyl ketone as a solvent, adding a tetraethylammonium bromide acetic acid solution, and measuring using a 0.1 mol/L perchloric acid-acetic acid solution with a potentiometric titrator.

2) Melting point A DSC peak temperature was obtained with a differential scanning calorimeter (EXSTAR6000 DSC/6200, manufactured by SII Nanotechnology Co., Ltd.) under the condition of a heating rate of 5°C/min. That is, this DSC peak temperature was taken as the melting point of the resin.

3) Melt viscosity Measured at 150°C using a CAP2000H rotational viscometer manufactured by BROOKFIELD.

4) Softening point Measured by the ring and ball method according to JIS-K-2207.

5) GPC Measurement A column (TSKgelG4000HXL, TSKgelG3000HXL, TSKgelG2000HXL, manufactured by Tosoh Corporation) in series with a main body (HLC-8220GPC manufactured by Tosoh Corporation) was used, and the column temperature was set to 40°C. Tetrahydrofuran (THF) was used as an eluent at a flow rate of 1 mL/min, and a differential refractive index detector was used as a detector. As a measurement sample, 0.1 g of the sample was dissolved in 10 mL of THF and filtered through a microfilter, and 50 μL of the solution was used. For data processing, GPC-8020 model II version 6.00 manufactured by Tosoh Corporation was used.

6) Glass transition point (Tg)
Tg was determined with a thermomechanical measurement device (EXSTAR6000TMA/6100 manufactured by SII Nanotechnology Co., Ltd.) under the condition of a temperature increase rate of 10° C./min.

7) 5% weight loss temperature (Td5), residual carbon ratio Using a thermogravimetry/differential thermal analyzer (EXSTAR6000TG/DTA6200, manufactured by SII Nanotechnology), under a nitrogen atmosphere, at a heating rate of 10°C/min. , the 5% weight loss temperature (Td5) was measured. Also, the weight loss at 700° C. was measured and calculated as the residual charcoal rate.

8) Dielectric constant and dielectric loss tangent According to IPC-TM-650 2.5.5.9, a material analyzer (manufactured by AGILENT Technologies) was used to obtain the dielectric constant and dielectric loss tangent at a frequency of 1 GHz by the capacitance method. .

9) Thermal conductivity Measured by the unsteady hot wire method using a NETZSCH LFA447 thermal conductivity meter.

Example 1
50.0 g of 4,4′-dihydroxybiphenyl and 50.0 g of 2,2′-dihydroxybiphenyl were dissolved in 500 g of epichlorohydrin and 75 g of diethylene glycol dimethyl ether, 8.8 g of 48% sodium hydroxide was added at 60° C., and the mixture was stirred for 1 hour. . After that, under reduced pressure (about 130 Torr), 78.8 g of a 48% sodium hydroxide aqueous solution was added dropwise over 3 hours. During this time, the generated water was removed from the system by azeotroping with epichlorohydrin, and the distilled epichlorohydrin was returned to the system. After completion of the dropwise addition, the reaction was continued for an additional 1 hour to remove water, epichlorohydrin was distilled off, 370 g of toluene was added, and the salt was removed by washing with water. After removing water by liquid separation, toluene was distilled off under reduced pressure to obtain 130 g of a white crystalline epoxy resin (epoxy resin A). The epoxy equivalent was 159, the hydrolyzable chlorine was 55 ppm, the melting point was 123°C, and the viscosity at 150°C was 7.0 mPa·s. The n=0 (monomer) of the epoxy resin obtained from 4,4'-dihydroxybiphenyl determined by GPC measurement was 36.4%. Also, n=0 (monomer) of the epoxy resin obtained from 2,2'-dihydroxybiphenyl was 37.9%. The ratio of n=1 or more was 25.7%.

Example 2
70.0 g of 4,4′-dihydroxybiphenyl and 30.0 g of 2,2′-dihydroxybiphenyl were dissolved in 500 g of epichlorohydrin and 75 g of diethylene glycol dimethyl ether, 8.8 g of 48% sodium hydroxide was added at 60° C., and the mixture was stirred for 1 hour. . After that, under reduced pressure (about 130 Torr), 78.8 g of a 48% sodium hydroxide aqueous solution was added dropwise over 3 hours. During this time, the generated water was removed from the system by azeotroping with epichlorohydrin, and the distilled epichlorohydrin was returned to the system. After completion of the dropwise addition, the reaction was continued for an additional 1 hour to remove water, epichlorohydrin was distilled off, 370 g of toluene was added, and the salt was removed by washing with water. Thereafter, after water was removed by liquid separation, toluene was distilled off under reduced pressure to obtain 125 g of a white crystalline modified epoxy resin (epoxy resin B). The epoxy equivalent was 157, the hydrolyzable chlorine was 89 ppm, the melting point was 141°C, and the viscosity at 150°C was 6.1 mPa·s. The n=0 (monomer) of the epoxy resin obtained from 4,4'-dihydroxybiphenyl determined by GPC measurement was 61.3%. Also, n=0 (monomer) of the epoxy resin obtained from 2,2'-dihydroxybiphenyl was 26.3%. The ratio of n=1 or more was 12.4%.

Comparative example 1
50.0 g of hydroquinone and 100.0 g of 4,4′-dihydroxybiphenyl were dissolved in 1000 g of epichlorohydrin and 150 g of diethylene glycol dimethyl ether, and 16.5 g of 48% sodium hydroxide was added at 60° C. and stirred for 1 hour. After that, under reduced pressure (about 130 Torr), 148.8 g of a 48% sodium hydroxide aqueous solution was added dropwise over 3 hours. During this time, the generated water was removed from the system by azeotroping with epichlorohydrin, and the distilled epichlorohydrin was returned to the system. After completion of the dropwise addition, the reaction was continued for an additional hour to remove water, epichlorohydrin was distilled off, 600 g of methyl isobutyl ketone was added, and the salt was removed by washing with water. Then, 13.5 g of 48% sodium hydroxide was added at 85° C., stirred for 1 hour, and washed with 200 mL of warm water. Thereafter, after water was removed by liquid separation, methyl isobutyl ketone was distilled off under reduced pressure to obtain 224 g of a white crystalline modified epoxy resin (epoxy resin C). The epoxy equivalent was 139, the hydrolyzable chlorine was 320 ppm, the melting point was 125°C, and the viscosity at 150°C was 3.4 mPa·s. The n=0 (monomer) of the epoxy resin obtained from 4,4'-dihydroxybiphenyl determined by GPC measurement was 67.2%. Also, the n=0 (monomer) of the epoxy resin obtained from hydroquinone is . It was 23.1%. The ratio of n=1 or more was 9.7%.

Comparative example 2
100.0 g of 2,2′-dihydroxybiphenyl was dissolved in 500 g of epichlorohydrin and 75 g of diethylene glycol dimethyl ether, 8.8 g of 48% sodium hydroxide was added at 60° C., and the mixture was stirred for 1 hour. After that, under reduced pressure (about 130 Torr), 78.8 g of a 48% sodium hydroxide aqueous solution was added dropwise over 3 hours. During this time, the generated water was removed from the system by azeotroping with epichlorohydrin, and the distilled epichlorohydrin was returned to the system. After completion of the dropwise addition, the reaction was continued for an additional 1 hour to remove water, epichlorohydrin was distilled off, 370 g of toluene was added, and the salt was removed by washing with water. After removing water by liquid separation, toluene was distilled off under reduced pressure to obtain 136 g of a liquid epoxy resin (epoxy resin D). The epoxy equivalent was 162, the hydrolyzable chlorine was 29 ppm, and the viscosity at 150°C was 6.2 mPa·s. The ratio of each component obtained by GPC measurement of the obtained resin was 78.4% for n=0 and 21.6% for n=1 or more.

Comparative example 3
100.0 g of 4,4′-dihydroxybiphenyl was dissolved in 700 g of epichlorohydrin and 105 g of diethylene glycol dimethyl ether, and then 87.8 g of a 48% aqueous sodium hydroxide solution was added dropwise at 60° C. under reduced pressure (about 130 Torr) over 3 hours. . During this time, the generated water was removed from the system by azeotroping with epichlorohydrin, and the distilled epichlorohydrin was returned to the system. After the dropwise addition was completed, the reaction was continued for 1 hour, dehydrated, cooled to room temperature, and filtered to recover the precipitate. Thereafter, the precipitate was washed with water to remove salts, and dried to obtain 137 g of a crystalline powdery epoxy resin (epoxy resin E). The epoxy equivalent was 163 and the melting point was 172°C. The ratio of each component determined by GPC measurement of the obtained resin was 93.7% for n=0 and 5.9% for n=1 or more.

Confirmation of Solvent Solubility Solvent solubility was determined by adding 5 g of a solvent (methyl ethyl ketone, toluene, cyclohexanone) to epoxy resins A and B obtained in Examples 1 and 2, and epoxy resins C and E obtained in Comparative Examples 1 and 3. was added so that the solid content concentration was 10% by weight, 15% by weight, and 20% by weight, and the mixture was sufficiently stirred at room temperature, and then the insoluble matter was visually confirmed. The case where insoluble matter was present was evaluated as x, and the case where there was no insoluble matter was evaluated as ◯. In addition, Δ indicates that the insoluble matter was confirmed to dissolve when the insoluble matter was confirmed to be heated to 60°C. Table 1 shows the results.

Examples 3, 4 and Comparative Examples 4-7
As epoxy resin components, epoxy resins A and B obtained in Examples 1 and 2, epoxy resins C, D and E obtained in Comparative Examples 1, 2 and 3, and a biphenyl-based epoxy resin (epoxy resin F: Japan Epoxy Resin YX-4000H; epoxy equivalent 195) was used, and a phenol novolak resin (PN; hydroxyl equivalent 105 g/eq., softening point 67° C.) was used as a curing agent. Using triphenylphosphine as a curing accelerator, an epoxy resin composition having the composition shown in Table 2 was obtained. Numerical values in the table indicate parts by weight 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 subjected to various physical property measurements.

As is clear from these results, the epoxy resins obtained in the examples have excellent solvent solubility, and the cured products thereof have excellent thermal conductivity. Furthermore, it was found that the thermal stability was good and the dielectric loss tangent was low.

Claims (5)

An epoxy resin represented by the following general formula (1), wherein the total amount of n = 0 isomers, which is a mixture of monomers derived from 4,4'-dihydroxybiphenyl and 2,2'-dihydroxybiphenyl, is 90 wt% or less. and wherein the total amount of n=1 or more , which is a mixture of polymers derived from 4,4′-dihydroxybiphenyl and 2,2′-dihydroxybiphenyl, is 5 wt % to 35 wt %.

(Wherein, G represents a glycidyl group, and n represents a number from 0 to 10.) An epoxy resin obtained by reacting a mixture containing 4,4′-dihydroxybiphenyl and 2,2′-dihydroxybiphenyl as monomers with epichlorohydrin and represented by the general formula (1), The total of n = 0 , which is a monomer mixture derived from monomers, is 90 wt% or less, and the total of n = 1 or more , which is a multimer mixture derived from each monomer containing a copolymer structure The epoxy resin according to claim 1, wherein is 5 to 35 wt%. Obtained by reacting a mixture obtained by mixing 0.1 to 10 parts by weight of 2,2'-dihydroxybiphenyl with 1 part by weight of 4,4'-dihydroxybiphenyl with epichlorohydrin, and having an epoxy equivalent in the range of 130 to 190. 2. The epoxy resin of claim 1, wherein a An epoxy resin composition comprising an epoxy resin and a curing agent, wherein the epoxy resin according to any one of claims 1 to 3 is included as an essential component as part or all of the epoxy resin. A cured resin obtained by curing the resin composition according to claim 4 .

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