JP4271631B2 - Method for producing epoxy resin crystallized product - Google Patents

Description

  The present invention relates to a crystallized tetramethylbiphenyl type epoxy resin that can be easily blended with a curing agent, a method for producing the crystallized epoxy resin, and a curable epoxy excellent in various physical properties using the crystallized epoxy resin. The present invention relates to a resin composition.

Epoxy resins are used in a wide range of fields such as adhesion, casting, sealing, lamination, molding and painting because of their excellent cured properties and ease of handling.
Generally, epoxy resins are mixed (blended) with various additives such as curing agents, and then molded and cured as curable epoxy resin compositions. Otherwise, the curing reaction does not proceed sufficiently or the cured product becomes heterogeneous and the performance cannot be fully exhibited.

  Since tetramethylbiphenyl type epoxy resin obtained by reaction of 4,4′-dihydroxy-3,3 ′, 5,5′-tetramethylbiphenyl and epihalohydrin becomes a crystal having a melting point of 100 ° C. to 120 ° C., It is widely used for applications such as powder coatings and semiconductor encapsulants that are treated as solids at room temperature, and are heated and melted and flowed during molding and curing. However, since it is a crystal, compatibility with a curing agent or the like is slow, and there is a drawback that poor mixing tends to occur. Therefore, if the temperature is raised to the melting point or higher during blending for uniform mixing, the reaction with the curing agent proceeds at that time and fluidity is liable to occur during molding. Further, if the mixing time is lengthened, the productivity is lowered and it is industrially disadvantageous.

  The present invention relates to a tetramethylbiphenyl-type epoxy resin crystallized product that can be easily blended with a curing agent, a method for producing the epoxy resin crystallized product, and a curable epoxy resin excellent in various physical properties using the epoxy resin crystallized product. Relates to the composition.

  As a result of various studies to solve the above problems, the present inventors have found that crystals of a tetramethylbiphenyl type epoxy resin having a specific melting endothermic pattern are compatible with a curing agent and the like quickly and uniformly. It has been found that a curable epoxy resin composition can be easily obtained, and by taking specific crystallization conditions, it has been found that a crystallized tetramethylbiphenyl type epoxy resin having a specific compatibility can be obtained quickly. The present invention has been completed.

The present invention relates to an invention of a method for producing an epoxy resin crystallized product among the following inventions.
(1) A crystallized product of an epoxy resin derived from 4,4′-dihydroxy-3,3 ′, 5,5′-tetramethylbiphenyl and epihalohydrin at a rate of 10 ° C. per minute using a DSC apparatus An epoxy resin crystallized product having a ratio of an endothermic amount between 50 ° C. and 130 ° C. and an endothermic amount between 80 ° C. and 125 ° C. measured by raising the temperature at 1.03 or more.

(2) The ratio of the endotherm between 50 ° C. and 130 ° C. and the endotherm between 80 ° C. and 125 ° C. measured at a rate of 10 ° C. per minute using the DSC apparatus is 1.05. As described above, the epoxy resin crystallized product according to item (1), which has an endothermic peak temperature of 1.50 or lower and 110 ° C. or lower.

(3) An epoxy resin derived from 4,4′-dihydroxy-3,3 ′, 5,5′-tetramethylbiphenyl and epihalohydrin having an epoxy equivalent of 180 to 210 is cooled from a molten state of 105 ° C. or higher. From about 50 ° C. to 130 ° C. measured by heating at a rate of 10 ° C. per minute using a DSC apparatus, characterized in that crystallization is almost complete within 2 hours after the temperature becomes lower than 105 ° C. A method for producing an epoxy resin crystallized product, wherein the ratio of the endothermic amount between 80 ° C. and 125 ° C. is 1.03 or more.
(4) The ratio of the endotherm between 50 ° C. and 130 ° C. and the endotherm between 80 ° C. and 125 ° C. measured at a rate of 10 ° C. per minute using the DSC apparatus is 1.05. The method for producing an epoxy resin crystallized product as described in (3) above, wherein the temperature is 1.50 or less and the endothermic peak temperature is 110 ° C. or less.

(5) Either a method of adding a crystal nucleus or a method of applying a shearing force when cooling from a molten state of 105 ° C. or higher and crystallizing almost completely within 2 hours after a temperature lower than 105 ° C. One or both methods are employed, The method for producing an epoxy resin crystallized product according to any one of (3) or (4).

(6) A crystallized product of an epoxy resin derived from 4,4′-dihydroxy-3,3 ′, 5,5′-tetramethylbiphenyl and epihalohydrin at a rate of 10 ° C. per minute using a DSC apparatus An epoxy resin crystallized product and a curing agent for epoxy resin, in which the ratio of the endothermic amount between 50 ° C and 130 ° C and the endothermic amount between 80 ° C and 125 ° C, measured by raising the temperature at 1.0 ° C, is 1.03 or more. A curable epoxy resin composition that is blended as a component.

(7) The epoxy resin crystallized product has an endotherm between 50 ° C. and 130 ° C. and an endotherm between 80 ° C. and 125 ° C. measured by heating at a rate of 10 ° C. per minute using a DSC apparatus. The curable epoxy resin composition according to item (6), wherein the ratio is 1.05 or more and 1.50 or less and the endothermic peak temperature is 110 ° C. or less.

  The epoxy resin crystallized product of the present invention is easy to mix because it is compatible with a curing agent and the like. Moreover, according to the method for producing a crystallized epoxy resin of the present invention, the crystallized epoxy resin can be easily produced. Furthermore, since the curable epoxy resin composition of the present invention in which the epoxy resin crystallized product is blended has a uniform curing reaction, it has excellent curability and various cured physical properties.

  The epoxy resin crystallized product of the present invention is a crystallized product of an epoxy resin derived from 4,4′-dihydroxy-3,3 ′, 5,5′-tetramethylbiphenyl and epihalohydrin, and its melting endothermic pattern is The ratio of the endotherm between 50 ° C. and 130 ° C. and the endotherm between 80 ° C. and 125 ° C. measured at a rate of 10 ° C. per minute using a DSC apparatus is 1.03 or more. Preferably, it is 1.05 or more and 1.50 or less, More preferably, it is 1.06 or more and 1.40 or less. The endothermic peak temperature is preferably 110 ° C. or lower, and more preferably 109 ° C. or lower.

The endothermic amount is measured by using a DSC apparatus (differential scanning calorimeter) to raise 5 to 20 mg of crystalline powder at a rate of 10 ° C. per minute, and the obtained DSC curve has a straight line between the 50 ° C. and 130 ° C. points. And can be calculated from the area of the portion surrounded by the straight line and the DSC curve. The endothermic amount between 80 ° C. and 125 ° C. is obtained in the same manner. The endothermic peak temperature is the apex temperature of the endothermic peak of the DSC curve.
If the ratio of the endothermic amount between 50 ° C. and 130 ° C. and the endothermic amount between 80 ° C. and 125 ° C. is too small, the compatibility with the curing agent becomes slow, and the effect of the present invention is not sufficient. Crystals having an excessive endothermic ratio are not sufficiently crystallized and are difficult to handle as solids. Crystals having an endothermic peak temperature that is too high are slow to dissolve with a curing agent or the like.

  The method for producing a crystallized epoxy resin of the present invention is not particularly limited as long as it is a method capable of obtaining a product having an endothermic ratio of a specified amount or more. However, even if the same tetramethylbiphenyl type epoxy resin is used, the crystal state changes depending on the crystallization conditions. Therefore, it is preferable to use the method for producing an epoxy resin crystallized product of the present invention in which the crystallization conditions are defined.

  The tetramethylbiphenyl type epoxy resin used in the method for producing a crystallized epoxy resin of the present invention is an epoxy resin derived from 4,4′-dihydroxy-3,3 ′, 5,5′-tetramethylbiphenyl and epihalohydrin. The production method and properties are not particularly limited, but the epoxy equivalent needs to be 180 to 210, preferably 181 or more and 200 or less. If the epoxy equivalent is too low, it is difficult to obtain crystals having a ratio of endotherms exceeding the specified value even with the method for producing a crystallized epoxy resin of the present invention. If the epoxy equivalent is too high, crystallization is completed within a specified time. It becomes difficult.

  In the method for producing a crystallized epoxy resin of the present invention, first, a tetramethylbiphenyl type epoxy resin is placed in a molten state at 105 ° C. or higher. Subsequently, it is cooled and crystallized to below the melting point, but it is crystallized almost completely within 2 hours, preferably within 1 hour and 30 minutes, more preferably within 1 hour after the resin temperature becomes lower than 105 ° C. . Nearly complete crystallization means that it can be handled as a solid. The shorter the crystallization time, the more remarkable the effect of the present invention. When the crystallization time is too long, the epoxy resin crystallized product of the present invention cannot be obtained.

There are various methods for shortening the crystallization time, and there are no specific rules. However, a method of adding a separately prepared crystal nucleus or a method of adding shearing force to the resin by stirring or kneading can be easily performed in a short time. It is preferable in that it can be crystallized.
The preferred crystallization temperature varies depending on other conditions, but is usually 10 to 90 ° C., preferably 20 to 80 ° C.

The curable epoxy resin composition of the present invention is a curable epoxy resin composition comprising the epoxy resin crystallized product of the present invention and an epoxy resin curing agent as essential components.
Epoxy resins other than the crystallized epoxy resin of the present invention can also be blended in the curable epoxy resin composition of the present invention. The epoxy resin that can be used in combination is not particularly specified, and any epoxy resin other than the crystallized epoxy resin of the present invention can be used.

  Examples of such epoxy resins include bisphenol A, bisphenol F, bisphenol AD, tetrabutyl bisphenol A, hydroquinone, methylhydroquinone, dimethylhydroquinone, dibutylhydroquinone, resorcin, methylresorcin, biphenol, dihydroxynaphthalene, dihydroxydiphenyl ether, dihydroxystilbene Various phenols such as phenol novolac resin, cresol novolak resin, bisphenol A novolak resin, dicyclopentadiene phenol resin, phenol aralkyl resin, naphthol novolak resin, terpene phenol resin, heavy oil modified phenol resin, brominated phenol novolak resin , Various phenols and hydroxybenzaldehyde , Epoxy resins produced from various phenolic compounds such as polyhydric phenol resin obtained by condensation reaction with various aldehydes such as crotonaldehyde, glyoxal, and epihalohydrin, and diaminodiphenylmethane, aminophenol, xylenediamine, etc. Examples thereof include epoxy resins produced from various amine compounds and epihalohydrin, epoxy resins produced from various carboxylic acids such as methylhexahydrophthalic acid and dimer acid, and epihalohydrin.

  The use ratio of the epoxy resin crystallized product of the present invention in the curable epoxy resin composition of the present invention is 10 to 100% by weight, preferably 20 to 100% by weight, based on all epoxy resin components. If the use ratio of the high performance epoxy resin composition of the present invention is small, the excellent properties of the tetramethylbiphenyl type epoxy resin are not exhibited.

  In the curable epoxy resin composition of the present invention, a curing agent for epoxy resin is blended as an essential component, but there is no particular designation, and any curing agent can be used as long as it is a curing agent for epoxy resin. is there.

  Examples of the curing agent that can be used include bisphenol A, bisphenol F, bisphenol AD, tetrabutylbisphenol A, hydroquinone, resorcin, methylresorcin, biphenol, tetramethylbiphenol, dihydroxynaphthalene, dihydroxydiphenyl ether, phenol novolac resin, and cresol novolac resin. Various polyphenols such as bisphenol A novolac resin, dicyclopentadiene phenol resin, terpene phenol resin, naphthol novolac resin, heavy oil modified phenol resin, brominated phenol novolac resin, and various phenols and hydroxybenzaldehyde, Multivalent phenol obtained by condensation reaction with various aldehydes such as crotonaldehyde and glyoxal Various phenolic resins such as methyl resin, acid anhydrides such as methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, pyromellitic anhydride, methylnadic acid, diethylenetriamine, isophoronediamine, diaminodiphenylmethane, diaminodiphenylsulfone, dicyandiamide, etc. And amines.

  Examples of the curing agent that initiates polymerization of the epoxy group include phosphine compounds such as triphenylphosphine, phosphonium salts such as tetraphenylphosphonium tetraphenylborate, 2-methylimidazole, 2-phenylimidazole, 2-ethyl- Imidazoles such as 4-methylimidazole, 2-undecylimidazole, 1-cyanoethyl-2-methylimidazole, 2,4-dicyano-6- [2-methylimidazolyl- (1)]-ethyl-S-triazine, 1 -Cyanoethyl-2-undecylimidazolium trimellitate, 2-methylimidazolium isocyanurate, 2-ethyl-4-methylimidazolium tetraphenylborate, 2-ethyl-1,4-dimethylimidazolium tetraphenylborate Any imidazolium salt, amines such as 2,4,6-tris (dimethylaminomethyl) phenol, benzyldimethylamine, ammonium salts such as triethylammonium tetraphenylborate, 1,5-diazabicyclo (5,4,0)- Diazabicyclo compounds such as 7-undecene and 1,5-diazabicyclo (4,3,0) -5-nonene, tetraphenylborate, phenol salt, phenol novolac salt, 2-ethylhexanoate and the like of these diazabicyclo compounds.

Further, a triflic acid salt, a boron trifluoride ether complex compound, a metal fluoroboron complex salt, a bis (perfluoroalkylsulfonyl) methane metal salt, an aryldiazonium compound, an aromatic onium salt, a di group of IIIa to Va elements carbonyl chelates, thiopyrylium salts, MF ₆ ^- form of VIb elements anion (wherein M is selected from phosphorus, antimony and arsenic), arylsulfonium complex salts, aromatic iodonium complex salts, aromatic sulfonium complex salt, bis [4- (Diphenylsulfonio) phenyl] sulfide-bis-hexafluorometal salts (for example, phosphates, arsenates, antimonates, etc.), arylsulfonium complex salts, aromatic sulfonium or iodonium salts of halogen-containing complex ions, etc. it can. These epoxy resin curing agents may be used alone or in combination of two or more.

The proportion of the curing agent used in the curable epoxy resin composition of the present invention is such that, when a compound having a group that reacts with an epoxy group is used, the total amount of the epoxy group in all epoxy resin components is 1 mol. The amount in which the total of the groups that react with the epoxy groups in the curing agent component is 0.5 to 2.0 mol is preferable, and more preferably the amount is 0.7 to 1.5 mol.
When a curing agent that initiates polymerization of an epoxy group is used as the curing agent component, 0.1 to 10 parts by weight is preferable with respect to 100 parts by weight of all epoxy resin components, and more preferably 0.3 to 3 parts by weight. 5 parts by weight.

In the curable epoxy resin composition of the present invention, an inorganic filler, a reinforcing fiber, a curing accelerator, a coupling agent, a plasticizer, a pigment, a solvent, a flame retardant, and the like can be appropriately blended as necessary. .
Examples of the inorganic filler include fused silica, crystalline silica, glass powder, alumina, and calcium carbonate. The shape is crushing or spherical. Various inorganic fillers may be used alone or in admixture of two or more. The amount used is 30 to 95% by weight of the total composition, preferably 50 to 95% by weight, more preferably 70 to 93% by weight.

The curing accelerator is a compound that accelerates the reaction between the epoxy group in the epoxy resin and the active group in the curing agent.
Examples of the curing accelerator include phosphine compounds such as tributylphosphine, triphenylphosphine, tris (dimethoxyphenyl) phosphine, tris (hydroxypropyl) phosphine, tris (cyanoethyl) phosphine, tetraphenylphosphonium tetraphenylborate, methyltributylphosphonium. Phosphonium salts such as tetraphenylborate, methyltricyanoethylphosphonium tetraphenylborate, 2-methylimidazole, 2-phenylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 1-cyanoethyl-2-methylimidazole, 2,4-dicyano-6- [2-methylimidazolyl- (1)]-ethyl-S-triazine, 2,4-dicyano-6- [2-un Imidazoles such as silimidazolyl- (1)]-ethyl-S-triazine, 1-cyanoethyl-2-undecylimidazolium trimellitate, 2-methylimidazolium isocyanurate, 2-ethyl-4-methylimidazolium tetra Imidazolium salts such as phenylborate, 2-ethyl-1,4-dimethylimidazolium tetraphenylborate, 2,4,6-tris (dimethylaminomethyl) phenol, benzyldimethylamine, tetramethylbutylguanidine, N-methylpiperazine Amines such as 2-dimethylamino-1-pyrroline, ammonium salts such as triethylammonium tetraphenylborate, 1,5-diazabicyclo (5,4,0) -7-undecene, 1,5-diazabicyclo (4,3 , 0) -5-Nonene 1, 4-diazabicyclo (2, 2, 2) - diazabicyclo compounds such as octane, tetraphenylborate thereof diazabicyclo compounds, phenol salts, phenol novolak salts and 2-ethyl hexanoate and the like.

Among these compounds serving as curing accelerators, tertiary amines, phosphine compounds, imidazole compounds, diazabicyclo compounds, and salts thereof are preferable.
These curing accelerators are used singly or in combination of two or more, and the amount used is 0.1 to 7% by weight based on the total epoxy resin component.

  The flame retardants include halogen flame retardants such as brominated epoxy resins, antimony compounds such as antimony trioxide, phosphorus flame retardants such as phosphate esters and phosphines, nitrogen flame retardants such as melamine derivatives, and hydroxylation. Examples thereof include inorganic flame retardants such as aluminum and magnesium hydroxide.

  Since the epoxy resin crystallized product of the present invention has a fast compatibility with a curing agent or the like, the compounding is easy, and the method for producing an epoxy resin crystallized product of the present invention can easily produce the epoxy resin crystallized product. In addition, since the curable epoxy resin composition of the present invention undergoes a uniform curing reaction, it is excellent in curability and various cured physical properties.

  Below, the manufacture example of a tetramethylbiphenyl type epoxy resin, the epoxy resin crystallized product of this invention, the manufacturing method of an epoxy resin crystallized product, and the Example and comparative example of a curable epoxy resin composition are given and explained in full detail.

(Tetramethylbiphenyl type epoxy resin production example)
In a 5 L three-necked flask equipped with a thermometer, a stirrer, and a cooling tube, 363 g of 4,4′-dihydroxy-3,3 ′, 5,5′-tetramethylbiphenyl, 1665 g of epichlorohydrin, and 2-propanol After 600 g was charged and heated to 50 ° C. to dissolve, 273 g of 48.5 wt% sodium hydroxide aqueous solution was added dropwise over 1 hour. During this time, the temperature was gradually raised, and the temperature inside the system was adjusted to 70 ° C. at the end of dropping. Thereafter, the reaction was carried out by maintaining at 70 ° C. for 30 minutes. After the reaction was completed, the product was washed with water to remove by-product salts and excess sodium hydroxide. Subsequently, excess epichlorohydrin and 2-propanol were distilled off from the product under reduced pressure to obtain a crude epoxy resin.

  This crude epoxy resin was dissolved in 750 g of methyl isobutyl ketone, 6 g of 48.5% by weight aqueous sodium hydroxide solution was added, and the mixture was reacted at a temperature of 70 ° C. for 1 hour. After the reaction was completed, sodium phosphate monobasic was added to neutralize excess sodium hydroxide and washed with water to remove by-product salts. Next, methyl isobutyl ketone was completely removed under reduced pressure while heating to obtain the desired epoxy resin. The state of the epoxy resin at this point is a molten state with a resin temperature of about 150 ° C.

Example 1
Crystal powder of tetramethylbiphenyl type epoxy resin prepared separately when 50 g of molten tetramethylbiphenyl type epoxy resin produced in the above production example is placed in a glass container and slowly cooled to a resin temperature of 70 ° C. 3 g was added and mixed quickly. When it was allowed to cool as it was, it became almost completely crystallized 25 minutes after the resin temperature reached 105 ° C., and it could be handled as a solid.

Table 1 shows the epoxy equivalent of this epoxy resin crystallized product, the endothermic amount between 50 ° C. and 130 ° C., the endothermic amount between 80 ° C. and 125 ° C., their ratio, and the endothermic peak temperature.
The DSC data was measured using a TA Instruments MDSC 2920 type apparatus at a sample amount of about 10 mg and a heating rate of 10 ° C. per minute. The endothermic amount was calculated automatically by a computer. (Refer to the DSC charts in FIGS. 1 and 2)

Example 2
50 g of the molten tetramethylbiphenyl type epoxy resin produced in the above production example was placed in a glass container, and gradually cooled and stirred vigorously with a glass rod for 5 minutes from the time when the resin temperature reached 70 ° C. During stirring, some crystals began to precipitate. As it was allowed to cool, it was crystallized almost completely after 15 minutes from the time when the resin temperature reached 105 ° C., and it could be handled as a solid.
Table 1 shows the epoxy equivalent of this epoxy resin crystallized product, the endothermic amount between 50 ° C. and 130 ° C., the endothermic amount between 80 ° C. and 125 ° C., their ratio, and the endothermic peak temperature.

Comparative Example 1
50 g of the molten tetramethylbiphenyl type epoxy resin produced in the above production example was placed in a glass container, allowed to stand, and allowed to cool. Crystal precipitation was very slow. From the point of time when the resin temperature reached 105 ° C., it was almost completely crystallized 3 hours later, and it was in a state of being handled as a solid.
Table 1 shows the epoxy equivalent of this epoxy resin crystallized product, the endothermic amount between 50 ° C. and 130 ° C., the endothermic amount between 80 ° C. and 125 ° C., their ratio, and the endothermic peak temperature. (Refer to the DSC charts in FIGS. 3 and 4)

Comparative Example 2
50 g of the molten tetramethylbiphenyl type epoxy resin produced in the above production example was placed in a glass container and dissolved in 50 g of methyl isobutyl ketone at about 100 ° C. The solution was gradually cooled and held at about 20 ° C. for about 5 hours. The precipitated needle crystals were separated by filtration and then vacuum-dried at 50 ° C. for about 5 hours to remove methyl isobutyl ketone, whereby an epoxy resin crystallized product was obtained.
Table 1 shows the epoxy equivalent of this epoxy resin crystallized product, the endothermic amount between 50 ° C. and 130 ° C., the endothermic amount between 80 ° C. and 125 ° C., their ratio, and the endothermic peak temperature.

Examples 3 and 4 and Comparative Examples 3 and 4
As shown in Table 2, as an epoxy resin component, the epoxy resin crystallized product produced in Examples 1 and 2 or Comparative Examples 1 and 2, a phenol aralkyl resin as a curing agent component, a fused silica powder as an inorganic filler, a curing Triphenylphosphine was used as an accelerator and carnauba wax was used as a release agent.
Next, each component was pulverized and mixed, and then kneaded at 70 ° C. for 5 minutes using a mixing roll. Each obtained mixture was taken out into a sheet and pulverized to obtain each curable epoxy resin composition.

The gel time of each curable epoxy resin composition was measured at 180 ° C. Each of these curable epoxy resin compositions was molded with a low-pressure transfer molding machine at a mold temperature of 180 ° C. and a molding time of 90 seconds to obtain each test piece, which was post-cured for 5 hours. The glass transition temperature and the bending strength at 23 ° C. of each test piece were measured and shown in Table 2.
The curable epoxy resin compositions produced in Examples 3 and 4 were excellent in curability, heat resistance and mechanical strength as compared with the curable epoxy resin compositions produced in Comparative Examples 3 and 4.

The figure which shows the example of a measurement of the endothermic amount between 50 degreeC and 130 degreeC of the epoxy resin crystallized substance of Example 1. FIG. The figure which shows the example of a measurement of the endothermic amount between 80 degreeC and 125 degreeC of the epoxy resin crystallized substance of Example 1. FIG. The figure which shows the example of a measurement of the endothermic amount between 50 degreeC and 130 degreeC of the epoxy resin crystallized material of the comparative example 1. FIG. The figure which shows the measurement example of the endothermic amount between 80 degreeC and 125 degreeC of the epoxy resin crystallized material of the comparative example 1. FIG.

Claims (2)

4,4'-dihydroxy-3,3 ', 5,5'-epoxy equivalent derived from a tetramethyl biphenyl and epihalohydrin epoxy resin is 210 to 180, and cooled from a molten state of above 105 ° C., Using a DSC apparatus characterized in that crystallization is performed almost completely within 2 hours by either or both of a method of adding crystal nuclei and a method of applying a shearing force after a temperature lower than 105 ° C. Production of an epoxy resin crystallized product having a ratio of an endotherm between 50 ° C. and 130 ° C. and an endotherm between 80 ° C. and 125 ° C. measured at a rate of 10 ° C./min. Method. The epoxy resin crystallized product produced by the above method has an endotherm between 50 ° C. and 130 ° C. and a temperature between 80 ° C. and 125 ° C. measured at a rate of 10 ° C. per minute using the DSC apparatus. 2. The epoxy resin crystallized product according to claim 1, which is an epoxy resin crystallized product having a ratio to an endothermic amount of 1.05 or more and 1.50 or less and an endothermic peak temperature of 110 ° C. or less. Method.

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