JP6139997B2 - Epoxy resin, epoxy resin composition, and cured product thereof - Google Patents

Description

  The present invention relates to an epoxy resin composition excellent in curability, high heat resistance, mechanical strength, high thermal conductivity and thermal decomposition stability, a cured product, and an epoxy resin used therefor.

  Epoxy resins have been used in a wide range of industrial applications, but their required performance has become increasingly sophisticated in recent years. Among them, as an epoxy resin composition excellent in high thermal conductivity, one using an epoxy resin having a mesogenic structure is known. For example, Patent Document 1 discloses a biphenol type epoxy resin and a polyhydric phenol resin. An epoxy resin composition containing a curing agent as an essential component is shown, and it is disclosed that it 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. Patent Document 2 discloses an epoxy compound having in its molecule two mesogenic structures connected by a bent chain. Furthermore, Patent Document 3 discloses a resin composition containing an epoxy compound having a mesogenic group.

Japanese Patent Laid-Open No. 7-90052 JP-A-9-118673 JP-A-11-323162 JP-A-4-255714 Japanese Patent Laid-Open No. 10-292032 WO2011 / 074517

  However, the epoxy resin having such a mesogenic structure has a high melting point, and when performing a mixing process, the high melting point component is difficult to dissolve and remains undissolved, resulting in a problem that curability and heat resistance are lowered. In addition, high temperature is 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 gelation time is shortened, so that the mixing process is severely limited and difficult to handle. When a soluble third component is added to make up for the drawback, the melting point of the resin is lowered to facilitate uniform mixing, but the cured product has a problem that the thermal conductivity is lowered.

  On the other hand, Patent Documents 4 and 5 disclose a biphenol aralkyl type epoxy resin and a resin composition thereof, which are described as being excellent in heat resistance, moisture resistance, mechanical properties, etc. None focused on thermal conductivity. Patent Document 6 describes an aralkyl type epoxy resin having a biphenyl ring and a composition containing the same.

  The object of the present invention is to provide a cured product having excellent curability and high heat resistance, mechanical strength, high thermal conductivity and thermal decomposition stability in applications such as lamination, molding, casting and adhesion. It is to provide an epoxy resin composition useful for circuit board materials such as a sealing material for electronic parts, a high heat dissipation sheet, and a cured product thereof. Another object is to provide an epoxy resin used in the epoxy resin composition.

（ここで、ｎは０〜２０の数を示す。） In the epoxy resin represented by the following general formula (1), the present invention has a weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) of 1,000 to 5 in a value excluding n = 0 component. The epoxy resin is characterized in that the n = 0 component is 30% or less in terms of area%.

(Here, n represents a number from 0 to 20.)

（ここで、ｎは０〜２０の数を示す。） Moreover, this invention is represented by the following general formula (a) by making 0.1-0.55 mol of aromatic condensing agents react with 1 mol of biphenol compounds, and a biphenol compound and an aromatic condensing agent. The above epoxy resin production method is characterized in that a polyvalent hydroxy resin is obtained and this is reacted with epichlorohydrin.

(Here, n represents a number from 0 to 20.)

  Furthermore, the present invention is an epoxy resin composition comprising the above epoxy resin and a curing agent as essential components. This epoxy resin composition can contain an inorganic filler as an essential component, and an inorganic filler having a thermal conductivity of 20 W / m · K or more is used as a part or all of the inorganic filler in this case. Can do. Moreover, the use of this epoxy resin composition can be expanded by dissolving or suspending it in a solvent.

  Furthermore, the present invention is a prepreg characterized by combining the above epoxy resin composition with a fibrous base material. Moreover, this invention is a hardened | cured material formed by hardening | curing said epoxy resin composition.

  If the epoxy resin composition containing the epoxy resin of the present invention is cured by heating, an epoxy resin cured product can be obtained. This cured product is curable, high heat resistance, mechanical strength, high thermal conductivity and stable thermal decomposition. It can be used suitably for applications such as sealing materials for electrical and electronic parts, circuit board materials such as high heat dissipation sheets, and the like.

It is a GPC chart of the epoxy resin A of this invention. It is a GPC chart of the epoxy resin B of this invention. It is a GPC chart of epoxy resin C for comparison.

  The epoxy resin of this invention is represented by General formula (1). In formula, n shows the number of 0-20. As the average value (number average) of n, the weight average molecular weight (Mw) measured by GPC is 1,000 to 5,000 excluding n = 0 component, and n = 0 component is the area of GPC. % Is a range satisfying that it is 30% or less of the whole, but preferably 1 to 6 as a whole. The content of the n = 0 component is preferably 1 to 20%, and the Mw is preferably 2000 to 4500.

  The epoxy resin can be produced by reacting the polyvalent hydroxy resin represented by the general formula (a) with epichlorohydrin. However, it is not restricted to this reaction method. The polyvalent hydroxy resin can be advantageously produced by reacting a biphenol with an aromatic condensing agent. Specifically, the biphenol compound and the aromatic condensing agent are represented by the above general formula (a) by reacting 0.1 to 0.55 mol of the aromatic condensing agent with respect to 1 mol of the biphenol compound. In this method, a polyvalent hydroxy resin is obtained and this is reacted with epichlorohydrin. In general formula (a), n is the same as in general formula (2).

  4,4′-dihydroxybiphenyl is suitable as a biphenol as a raw material for synthesizing the polyvalent hydroxy resin.

  As the aromatic condensing agent, p-xylylene glycol, α, α′-dimethoxy-p-xylene, α, α′-diethoxy-p-xylene, α, α′-diisopropoxy-p are used as the xylylene condensing agent. -Xylene, α, α'-dibutoxy-p-xylene, 1,4-di (α-hydroxyethyl) benzene, 1,4-di (α-methoxyethyl) benzene, 1,4-di (α-ethoxyethyl) ) Benzene, 1,4-di (α-isopropoxyethyl) benzene, 1,4-di (2-hydroxy-2-propyl) benzene, 1,4-di (2-methoxy-2-propyl) benzene, 1 , 4-di (2-ethoxy-2-propyl) benzene, dialkoxy compounds such as 1,4-di (2-isopropoxy-2-propyl) benzene, and p-divinylbenzene.

  Other examples of the aromatic condensing agent include divinyl compounds such as o-divinylbenzene, p-divinylbenzene, and m-divinylbenzene.

  In the reaction between the biphenols and the aromatic condensing agent, an excess amount of the bifunctional phenolic compound is used with respect to the aromatic condensing agent. The usage-amount of an aromatic condensing agent is 0.1-0.55 mol with respect to 1 mol of biphenols. Further, the amount of the aromatic condensing agent used in the case where the n = 0 component is not removed in the subsequent step is preferably 0.35 to 0.55 mol. In the case where n = 0 component is removed by a post-process, the amount is 0.2 to 0.55 mol, preferably 0.3 to 0.5 mol. When the molar ratio and the amount of the aromatic condensing agent used are more than 0.55 mol, the generation of n = 0 component is reduced, but the molecular weight itself is increased, and the softening point and melt viscosity of the resin are increased, which hinders the molding workability. If the amount is less than 0.1 mol, the amount of excess biphenols to be removed is increased after the reaction is completed, which is not industrially preferable. When this molar ratio (aromatic condensing agent / biphenol) is increased within the above range, the average value of n increases and the content of n = 0 component decreases. Therefore, by adjusting this molar ratio, n or Mw Can be controlled. Furthermore, the n = 0 component content can be largely controlled by removing the n = 0 component in the subsequent step as described above.

  Usually, this reaction is performed in the presence of a known acid catalyst such as an inorganic acid or an organic acid. Examples of such an acid catalyst include mineral acids such as hydrochloric acid, sulfuric acid, and phosphoric acid, organic acids such as formic acid, oxalic acid, trifluoroacetic acid, and p-toluenesulfonic acid, zinc chloride, aluminum chloride, iron chloride, Examples include Lewis acids such as boron trifluoride and solid acids such as activated clay, silica-alumina, and zeolite.

  Usually, this reaction is performed at 10 to 250 ° C. for 1 to 20 hours. Further, as a solvent in the reaction, for example, alcohols such as methanol, ethanol, propanol, butanol, ethylene glycol, methyl cellosolve, ethyl cellosolve, diglyme and triglyme, and aromatic compounds such as benzene, toluene, chlorobenzene and dichlorobenzene Of these, ethyl cellosolve, diglyme, triglyme and the like are particularly preferable. After completion of the reaction, the obtained polyvalent hydroxy resin may be removed by a method such as distillation under reduced pressure, washing with water or reprecipitation in a poor solvent, but as a raw material for the epoxidation reaction while leaving the solvent. It may be used.

  Moreover, it is preferable to attach | subject the obtained polyvalent hydroxy resin to the process of removing n = 0 component after completion | finish of reaction. In this step, for example, it is preferable to remove the n = 0 component by a method such as filtration using a poor solvent that does not dissolve the n = 0 component and dissolves the high molecular weight component of n = 1 or more. The poor solvent is not particularly limited as long as it does not substantially dissolve the n = 0 component. For example, alcohols such as ethylene glycol, methyl cellosolve, ethyl cellosolve, diglyme, triglyme, benzene, toluene, chlorobenzene, dichlorobenzene, etc. What mixed the ketones, such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, with the good solvent of an aromatic compound can use it preferably. In this step, it is possible to greatly reduce the content of the n = 0 component, but the content of the n = 0 component is preferably 1 to 20%, more preferably about 2 to 10%. is there.

  The removal process of n = 0 component can be performed even after epoxidation. In the removal step performed after epoxidation, it is preferable to remove the n = 0 component by a method such as filtration using a poor solvent in the same manner as in the above step. As the poor solvent in this case, since the epoxy resin has higher solubility than the polyvalent hydroxy resin, it can be said that the poor solvent is inferior in solubility. The poor solvent is not particularly limited as long as it does not substantially dissolve the n = 0 component. For example, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone are preferable.

  The epoxy resin of the present invention can be produced by reacting the above polyvalent hydroxy resin with epichlorohydrin. This reaction can be performed in the same manner as a normal epoxidation reaction. For example, after dissolving a polyvalent hydroxy resin in excess epichlorohydrin, the reaction is carried out at 50 to 150 ° C., preferably 60 to 120 ° C. for 1 to 10 hours in the presence of an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide. The method of letting it be mentioned. Under the present circumstances, the usage-amount of an alkali metal hydroxide is 0.8-1.2 mol with respect to 1 mol of hydroxyl groups in a polyvalent hydroxy compound, Preferably it is 0.9-1.0 mol. Epichlorohydrin is used in excess with respect to the hydroxyl group in the polyvalent hydroxy resin, but is usually 1.5 to 15 mol, preferably 2 to 8 mol, relative to 1 mol of the hydroxyl group in the polyvalent hydroxy compound. After completion of the reaction, excess epichlorohydrin is distilled off, the residue is dissolved in a solvent such as toluene, methyl isobutyl ketone, filtered, washed with water to remove inorganic salts, and then the solvent is distilled off to give a general formula. The epoxy resin represented by (1) can be obtained. In the case of epoxidation, when the epoxy group of the produced epoxy compound is ring-opened and condensed to form an oligomerized epoxy compound, a small amount of such an epoxy compound may be present.

  The softening point or melting point of the epoxy resin can be easily adjusted by changing the molar ratio of the biphenols and the crosslinking agent when synthesizing the polyvalent hydroxy resin that is the raw material of the epoxy resin. The softening point or melting point is preferably 130 ° C. or lower, more preferably 120 ° C. or lower, from the viewpoint of suppressing deterioration in physical properties due to undissolved remaining high melting point components during the mixing treatment. When the softening point or melting point is higher than this, physical properties such as curability and heat resistance tend to be lowered. Since the epoxy resin of this invention has few n = 0 components and low Mw, the characteristic of the hardened | cured material obtained from the epoxy resin composition using this improves.

  The epoxy resin composition of the present invention contains the epoxy resin of the present invention and a curing agent as essential components. Advantageously, these and inorganic fillers are essential components.

  As the curing agent to be blended in the epoxy resin composition of the present invention, polyhydric phenols are preferably used as the curing agent in fields where high electrical insulation properties such as semiconductor sealing materials are required. Below, the specific example of a hardening | curing agent is shown.

  Examples of polyhydric phenols include divalent phenols such as bisphenol A, bisphenol F, bisphenol S, fluorene bisphenol, hydroquinone, resorcin, catechol, biphenols, naphthalenediols, and tris- (4-hydroxyphenyl). ) Trivalent or higher typified by methane, 1,1,2,2-tetrakis (4-hydroxyphenyl) ethane, phenol novolak, o-cresol novolak, naphthol novolak, dicyclopentadiene type phenol resin, phenol aralkyl resin, etc. Phenols, further phenols, naphthols, or bisphenol A, bisphenol F, bisphenol S, fluorene bisphenol, 4,4'-biphenol, 2,2'-biphenol, hydroxyl Divalent phenols such as ethanol, resorcin, catechol, naphthalenediols, and formaldehyde, acetaldehyde, benzaldehyde, p-hydroxybenzaldehyde, p-xylylene glycol, p-xylylene glycol dimethyl ether, divinylbenzene, diisopropenylbenzene, dimethoxy Polyphenolic compounds synthesized by reaction with crosslinkers such as methyl biphenyls, divinyl biphenyls, diisopropenyl biphenyls, biphenyl aralkyl type phenol resins obtained from phenols and bischloromethyl biphenyls, naphthols and para Examples thereof include naphthol aralkyl resins synthesized from xylylene dichloride and the like.

  Other curing agent components can also be used, such as dicyandiamide, acid anhydrides, aromatic and aliphatic amines. In the epoxy resin composition of the present invention, one or more of these curing agents can be mixed and used.

  The amount of the curing agent is blended in consideration of an equivalent balance between the epoxy group in the epoxy resin and the functional group of the curing agent (a hydroxyl group in the case of polyhydric phenols). The equivalent ratio of epoxy resin and curing agent is usually in the range of 0.2 to 5.0, preferably in the range of 0.5 to 2.0, more preferably in the range of 0.8 to 1.5. It is. If it is larger or smaller than this, the curability of the epoxy resin composition is lowered, and the heat resistance, mechanical strength and the like of the cured product are lowered.

  Moreover, in this epoxy resin composition, you may mix | blend another kind of epoxy resin other than the epoxy resin represented by General formula (1) as an epoxy resin component. As other types of epoxy resins in this case, all ordinary epoxy resins having two or more epoxy groups in the molecule can be used. Examples include bisphenol A, bisphenol F, bisphenol S, fluorene bisphenol, 4,4′-biphenol, 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxybiphenyl, resorcin, naphthalenediols Trivalent or higher epoxides such as divalent phenols such as tris- (4-hydroxyphenyl) methane, 1,1,2,2-tetrakis (4-hydroxyphenyl) ethane, phenol novolak, o-cresol novolak, etc. Epoxidized products of phenols, epoxidized products of cocondensation resins obtained from dicyclopentadiene and phenols, epoxidized products of cocondensation resins obtained from cresols, formaldehyde and alkoxy-substituted naphthalenes, phenols and paraxylylene dichloride Obtained from etc. E Nord aralkyl resin epoxidized product, there phenols and bis-chloromethyl biphenyl biphenyl aralkyl type phenolic resins obtained from the epoxy compound, epoxidized naphthol aralkyl resin and the like which are synthesized from naphthols and para-xylylene dichloride and the like. These epoxy resins can be used alone or in combination of two or more. And the compounding quantity of the epoxy resin of this invention in the whole epoxy resin should be 5-100 wt%, Preferably it is the range of 60-100 wt%, and the compounding quantity of another kind of epoxy resin is 0-40 wt%. A range is preferable.

  Furthermore, a crosslinked elastic body can be contained in the epoxy resin composition for the purpose of reducing the stress of the cured product. When a crosslinked elastic body is blended, it is possible to significantly reduce the occurrence of package cracks in a thermal shock test of a cured product.

  The content of the cross-linked elastic body is preferably in the range of 3 to 30 parts by weight with respect to 100 parts by weight of the epoxy resin, preferably 5 to 20 parts by weight, and more preferably 5 to 15 parts by weight. If it is smaller than this, low elasticity is not sufficiently exhibited. On the other hand, if it is larger than this, the Tg of the cured product is lowered, the fluidity is lowered, and the moldability tends to be inferior.

  As the cross-linked elastic body, known materials can be used, but from the viewpoint of improving compatibility with the epoxy resin, it is preferable to use styrene rubber or acrylic rubber.

  When an inorganic filler is blended as an essential component, examples of the inorganic filler include spherical or crushed fused silica, silica powder such as crystalline silica, alumina powder, glass powder, or mica, talc, calcium carbonate, and alumina. , Hydrated alumina and the like, and a preferable blending amount when used for a semiconductor encapsulant is 70% by weight or more, and more preferably 80% by weight or more. The shape and particle size of the inorganic filler are not limited, but a spherical shape, a crushed shape, a flat shape, a fiber shape, or the like can be used, and the particle size or major axis is preferably in the range of 1 to 1000 μm. When the prepreg is used, the fiber length of the fibrous base material is preferably 10 mm or more, and the amount of the inorganic filler blended therein is preferably in the range of 10 to 70% by weight.

  For the purpose of imparting higher thermal conductivity, the inorganic filler is preferably as high as possible. It is preferably 20 W / m · K or more, more preferably 30 W / m · K or more, and still more preferably 50 W / m · K or more. At least a part of the inorganic filler, preferably 50 wt% or more, has a thermal conductivity of 20 W / m · K or more. The average thermal conductivity of the inorganic filler as a whole is improved in the order of 20 W / m · K or higher, 30 W / m · K or higher, and 50 W / m · K or higher.

  Examples of inorganic fillers having such thermal conductivity include inorganic powder fillers such as boron nitride, aluminum nitride, silicon nitride, silicon carbide, titanium nitride, zinc oxide, tungsten carbide, alumina, and magnesium oxide. It is done.

  In addition to the above essential components, other additives can be added to the epoxy resin composition of the present invention.

  In the epoxy resin composition of the present invention, an oligomer or a polymer compound such as polyester, polyamide, polyimide, polyether, polyurethane, petroleum resin, indene resin, indene-coumarone resin, phenoxy resin, etc. is used as another modifier. You may mix | blend suitably. The addition amount is usually in the range of 2 to 30 parts by weight with respect to 100 parts by weight of the epoxy resin.

  The epoxy resin composition of the present invention may contain additives such as pigments, refractory agents, thixotropic agents, coupling agents, fluidity improvers and the like.

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

  Furthermore, a curing accelerator can be used in the epoxy resin composition of the present invention as necessary. Examples include amines, imidazoles, organic phosphines, Lewis acids, etc., specifically 1,8-diazabicyclo (5,4,0) undecene-7, triethylenediamine, benzyldimethylamine, Tertiary amines such as ethanolamine, dimethylaminoethanol, tris (dimethylaminomethyl) phenol, 2-methylimidazole, 2-phenylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, 2- Imidazoles such as heptadecylimidazole, organic phosphines such as tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine, and phenylphosphine, tetraphenylphosphonium tetraphenylborate, tetraphenyl Tetraphenyl such as ruphosphonium / ethyltriphenylborate, tetrabutylphosphonium / tetrabutylborate, tetrasubstituted phosphonium / tetrasubstituted borate, 2-ethyl-4-methylimidazole / tetraphenylborate, N-methylmorpholine / tetraphenylborate, etc. There is boron salt. As addition amount, it is the range of 0.2-5 weight part normally with respect to 100 weight part of epoxy resins.

  Further, if necessary, the resin composition of the present invention includes a release agent such as carnauba wax and OP wax, a coupling agent such as γ-glycidoxypropyltrimethoxysilane, a colorant such as carbon black, and trioxide. Flame retardants such as antimony and lubricants such as calcium stearate can be used.

  The epoxy resin composition of the present invention can be advantageously used as a varnish state (referred to as varnish) in which a part or all of the epoxy resin composition is dissolved in an organic solvent. When a solvent-insoluble component such as an inorganic filler is included, it is not necessary to dissolve it, but it is desirable to make it a suspended state to obtain a uniform solution. It is desirable to dissolve the epoxy resin and the curing agent in the resin composition, but the epoxy resin of the present invention has the characteristics that the solubility is excellent and the solid content hardly precipitates in the storage state. If a part of the epoxy resin in the varnish becomes a solid and separates, the properties of the cured product are inferior.

  The epoxy resin composition of the present invention is preferably a fibrous base material such as a glass cloth, an aramid nonwoven fabric, a liquid crystal polymer polyester nonwoven fabric, etc. after a resin component is dissolved in a solvent (varnish). By removing the solvent after impregnating, the prepreg in which the epoxy resin composition and the fibrous base material are combined can be obtained. Moreover, it can be set as a laminated body by apply | coating the said varnish on sheet-like objects, such as copper foil, stainless steel foil, a polyimide film, and a polyester film depending on the case. Moreover, it can be set as a laminated body by laminating | stacking the said prepreg two or more, and also laminating | stacking a prepreg and the said sheet-like material.

  If the epoxy resin composition of the present invention is cured by heating, an epoxy resin cured product can be obtained, and this cured product is excellent in terms of low hygroscopicity, high heat resistance, adhesion, flame retardancy, and the like. Become. This cured product can be obtained by molding the epoxy resin composition by a method such as casting, compression molding, transfer molding or the like. The temperature at this time is usually in the range of 120 to 220 ° C.

  Hereinafter, based on a synthesis example, an Example, and a comparative example, this invention is demonstrated concretely. The solvent in the synthesis examples is diethylene glycol dimethyl ether.

Synthesis Example 1 (Example 1)
In a 2 L 4-neck flask, 186 g (1.0 mol) of 4,4′-dihydroxybiphenyl, 69 g (0.5 mol) of p-xylylene glycol, 743 g of diethylene glycol dimethyl ether as a solvent, p-toluenesulfonic acid 2 as an acid catalyst .55 g was charged and the temperature was raised to 160 ° C. Next, it was made to react for 3 hours, stirring at 160 degreeC. Next, a part of the solvent was distilled off under reduced pressure. The n = 0 body in the GPC measurement of the obtained resin (polyvalent hydroxy resin) was 27%. Into 237 g of the obtained resin, 740 g of epichlorohydrin was charged and dissolved. Subsequently, 150.8 g of a 49% aqueous sodium hydroxide solution was added dropwise at 75 ° C. under reduced pressure over 4 hours, and water and epichlorohydrin distilled under reflux during the dropping were separated in a separation tank, and epichlorohydrin was returned to the reaction vessel. Water reacted outside the system. After completion of the reaction, the salt produced by filtration was removed, and after further washing with water, epichlorohydrin was distilled off to obtain 279 g of an epoxy resin (epoxy resin A). The epoxy equivalent of the obtained resin was 185 g / eq. In the GPC measurement, n = 0 isomer was 25%, and the molecular weight excluding the n = 0 component was Mw: 3,687, Mn: 1,515, Mw / Mn: 2.434. The peak temperature (melting point) in DSC measurement was 125 ° C., and the melt viscosity at 150 ° C. was 0.48 Pa · s.

Synthesis Example 2 (Example 2)
In a 2 L 4-neck flask, 186 g (1.0 mol) of 4,4′-dihydroxybiphenyl, 69 g (0.5 mol) of p-xylylene glycol, 743 g of a solvent, and 2.55 g of p-toluenesulfonic acid as an acid catalyst. The temperature was raised to 160 ° C. Next, it was made to react for 3 hours, stirring at 160 degreeC. Next, after partially distilling off the solvent under reduced pressure, 415 g of toluene and 138 g of methyl isobutyl ketone were charged and stirred, and after cooling to room temperature, the n = 0 body precipitated by filtration was removed, and the solvent was distilled off. . The n = 0 body in the GPC measurement of the resin was 7%. Into 165 g of the obtained resin, 477 g of epichlorohydrin was charged and dissolved. Subsequently, 97.1 g of a 49% aqueous sodium hydroxide solution was added dropwise at 75 ° C. under reduced pressure over 4 hours, and water and epichlorohydrin refluxed during the addition were separated in a separation tank, and epichlorohydrin was returned to the reaction vessel. Water reacted outside the system. After completion of the reaction, the salt produced by filtration was removed, and after further washing with water, epichlorohydrin was distilled off to obtain 190 g of an epoxy resin (epoxy resin B). The epoxy equivalent of the obtained resin was 196 g / eq. In the GPC measurement, n = 0 isomer was 6%, and the molecular weight excluding the n = 0 component was Mw: 3,360, Mn: 1,739, Mw / Mn: 1.932. The peak temperature (melting point) in DSC measurement was 109 ° C., and the melt viscosity at 150 ° C. was 26.4 Pa · s.

Synthesis example 3
In a 2 L four-necked flask, 186 g (1.0 mol) of 4,4′-dihydroxybiphenyl, 41 g (0.3 mol) of p-xylylene glycol, 743 g of solvent, and 2.27 g of p-toluenesulfonic acid as an acid catalyst. The temperature was raised to 160 ° C. Next, it was made to react for 3 hours, stirring at 160 degreeC. Next, a part of the solvent was distilled off under reduced pressure. The n = 0 body in the GPC measurement of the obtained resin was 46%. Into 217 g of the obtained resin, 740 g of epichlorohydrin was charged and dissolved. Subsequently, 137.9 g of a 49% aqueous sodium hydroxide solution was added dropwise at 75 ° C. under reduced pressure over 4 hours, and water and epichlorohydrin refluxed during the addition were separated in a separation tank, and epichlorohydrin was returned to the reaction vessel. Water reacted outside the system. After completion of the reaction, the salt produced by filtration was removed, and after further washing with water, epichlorohydrin was distilled off to obtain 255 g of epoxy resin (epoxy resin C). The epoxy equivalent of the obtained resin was 174 g / eq. In the GPC measurement, n = 0 isomer was 43%, and the molecular weight excluding the n = 0 component was Mw: 1,875, Mn: 1,118, Mw / Mn: 1.777. The peak temperature (melting point) in DSC measurement was 139 ° C., and the melt viscosity at 150 ° C. was 0.042 Pa · s.

Synthesis example 4
In a 2 L four-necked flask, 186 g (1.0 mol) of 4,4′-dihydroxybiphenyl, 28 g (0.2 mol) of p-xylylene glycol, 743 g of solvent, and 2.14 g of p-toluenesulfonic acid as an acid catalyst. The temperature was raised to 160 ° C. Next, it was made to react for 3 hours, stirring at 160 degreeC. Next, a part of the solvent was distilled off under reduced pressure. The n = 0 isomer in the GPC measurement of the obtained resin was 59%. Into 206 g of the obtained resin, 740 g of epichlorohydrin was charged and dissolved. Subsequently, 131.4 g of a 49% aqueous sodium hydroxide solution was added dropwise at 75 ° C. under reduced pressure over 4 hours, and water and epichlorohydrin distilled under reflux during the dropping were separated in a separation tank, and epichlorohydrin was returned to the reaction vessel. Water reacted outside the system. After completion of the reaction, the salt produced by filtration was removed, and after further washing with water, epichlorohydrin was distilled off to obtain 243 g of an epoxy resin (epoxy resin D). The epoxy equivalent of the obtained resin was 172 g / eq. The n = 0 body in GPC measurement was 55%, the peak temperature (melting point) in DSC measurement was 146 ° C., and the melt viscosity at 150 ° C. was 0.020 Pa · s.

Examples 3-4, Comparative Examples 1-3
Epoxy resins obtained by kneading the obtained epoxy resins A to D, curing agents, inorganic fillers, triphenylphosphine as a curing accelerator, and other additives at the blending ratios shown in Table 3 above. A composition was prepared. The numerical value in a table | surface shows the weight part in a mixing | blending.

  Other ingredients used are shown below. PN was used as a curing agent, spherical alumina was used as an inorganic filler, carnauba wax was used as a release agent, and carbon black was used as a colorant.

Epoxy resin E: o-cresol novolac type epoxy resin (epoxy equivalent 200, softening point 65 ° C., manufactured by Nippon Steel Chemical Co., Ltd.)
PN: phenol novolak (PSM-4261 (manufactured by Gunei Chemical), OH equivalent 103, softening point 82 ° C.)
Spherical alumina: Product name; DAW-100, manufactured by Denki Kagaku Kogyo Co., Ltd., thermal conductivity 38 W / m · K
Triphenylphosphine: product name; Hokuko TPP, carnauba wax manufactured by Hokuko Chemical Co., Ltd .: product name; purified carnauba wax No. 1. Carbon black manufactured by Celerica NODA Co., Ltd .: Product name; MA-100, manufactured by Mitsubishi Chemical Corporation

  This epoxy resin composition was molded at 175 ° C., and further post-cured at 175 ° C. for 12 hours to obtain a cured product test piece, which was then subjected to various physical property measurements. The results are shown in Table 3.

Test conditions for the epoxy resin, the epoxy resin composition and the cured product are shown below.
1) Measurement of epoxy equivalent Using a potentiometric titrator, methyl ethyl ketone was used as a solvent, a brominated tetraethylammonium acetic acid solution was added, and a 0.1 mol / L perchloric acid-acetic acid solution was measured with a potentiometric titrator.

2) Melting | fusing point DSC peak temperature was calculated | required on the conditions of the temperature increase rate of 5 degree-C / min with the differential scanning calorimetry apparatus (SII nanotechnology Co., Ltd. EXSTAR6000 DSC / 6200). That is, this DSC peak temperature was taken as the melting point of the epoxy resin.

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

4) Gel time (seconds)
According to JISK6910, it measured at 175 degreeC.
5) Glass transition point (Tg)
Tg was calculated | required on the conditions of the temperature increase rate of 10 degree-C / min with the thermomechanical measuring apparatus (SII nanotechnology Co., Ltd. product EXSTAR6000TMA / 6100).
6) Weight retention (wt%)
Using a thermostat with a rotating frame, the weight retention (wt%) was determined from the difference between the weight of the test piece after 1000 hours at 250 ° C. and the weight of the test piece before heating.
7) Bending strength According to JISK6911, it measured at normal temperature by the 3 point | piece bending test method.

8) Thermal conductivity Thermal conductivity was measured by an unsteady hot wire method using an LFA447 type thermal conductivity meter manufactured by NETZSCH.

9) Solvent Solubility Solvent solubility is a resin solution in which cyclopentanone is used as a solvent and the epoxy resin composition shown in Table 1 is prepared and the epoxy resin composition is dissolved so as to have a solid content concentration of 50 wt%. It was allowed to stand at room temperature and evaluated by the number of days (hours) until a precipitate was confirmed. The results are shown in Table 2.

Claims (10)

The following general formula (1)

(Here, n represents a number from 0 to 20.)
In the epoxy resin represented by the formula, the weight average molecular weight (Mw) measured by gel permeation chromatography is 1,000 to 5,000 excluding n = 0 component, and n = 0 component is area%. An epoxy resin characterized by being 30% or less of the total.   2. The epoxy resin according to claim 1, wherein n = 0 component is 10% or less in area% measured by gel permeation chromatography. By reacting the biphenol compound and the aromatic condensing agent with 0.1 to 0.55 mol of the aromatic condensing agent with respect to 1 mol of the biphenol compound, a polyvalent hydroxy resin represented by the following general formula (a) is obtained. The method for producing an epoxy resin according to claim 1, wherein the epoxy resin is obtained by reacting with epichlorohydrin.

(Here, n represents a number from 0 to 20.)   The method for producing an epoxy resin according to claim 3, wherein after obtaining the polyvalent hydroxy resin, a step of removing the n = 0 component is provided and then reacted with epichlorohydrin.   The method for producing an epoxy resin according to claim 3, further comprising a step of removing n = 0 component after the epoxy resin is formed.   An epoxy resin composition comprising the epoxy resin according to claim 1 or 2 and a curing agent as essential components.   An epoxy resin composition comprising an epoxy resin, a curing agent and an inorganic filler as essential components, and using an inorganic filler having a thermal conductivity of 20 W / m · K or more as part or all of the inorganic filler. The epoxy resin composition according to claim 6.   The epoxy resin composition according to claim 6 or 7, wherein the epoxy resin composition is dissolved or suspended in a solvent.   A prepreg comprising the epoxy resin composition according to any one of claims 6 to 8 combined with a fibrous base material.   An epoxy resin cured product obtained by curing the epoxy resin composition according to any one of claims 6 to 8.

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