JP4354242B2 - Novel crystalline epoxy resin, curable epoxy resin composition and cured product thereof - Google Patents

Description

The present invention is a novel material that is solid at room temperature, has excellent handleability, has a very low melt viscosity in the molten state, has excellent curability, and provides a cured product having excellent mechanical strength, heat resistance, and moisture resistance. The present invention relates to an epoxy resin and a method for producing the same, and further useful for applications such as sealing materials, molding materials, casting materials, laminated materials, composite materials, adhesives, and powder coatings for electrical and electronic parts. The present invention relates to a curable epoxy resin composition containing an epoxy resin and a cured product thereof.

Epoxy compounds are cured with various curing agents to give cured products with excellent mechanical properties, moisture resistance, electrical properties, etc., so sealing materials for electrical and electronic parts, molding materials, casting materials, laminate materials It is used in a wide range of fields such as composite materials, adhesives and powder coatings. However, with the advancement of technology, there is an increasing demand for higher performance of epoxy compounds, and conventional epoxy compounds cannot meet the demand. For example, in the field of electrical and electronic applications, low-viscosity epoxy resins are desired as electronic parts become smaller and thinner, and this is sufficient for narrow gaps inside smaller parts. This is because it is necessary to feed resin. As low-viscosity epoxy resins , diglycidyl ethers of bisphenol A and diglycidyl ethers of bisphenol F are widely used, but these epoxy resins are liquid or viscous at room temperature and are difficult to handle depending on the application. Work is inferior. Further, cured bodies using these epoxy resins are not sufficient in mechanical strength, heat resistance and moisture resistance.
In order to solve these problems, a technique using an epoxy resin having crystallinity at room temperature or higher has been proposed. For example, tetramethylbiphenyl type epoxy resin (Patent Document 1), stilbene type epoxy resin (Patent Document 2), and the like. However, these epoxy resins have a bulky substituent in the vicinity of the epoxy group and thus have a high melt viscosity and are not sufficient in terms of curability. Moreover, although the hardened | cured material using these epoxy resins improves somewhat compared with the hardened | cured material using the above-mentioned bisphenol A type epoxy resin about heat resistance and moisture resistance, it is inadequate depending on a use.
Japanese Patent Publication No. 7-53791 Japanese Patent Laid-Open No. 9-12474

The present invention is a novel material that is solid at room temperature, has excellent handleability, has a very low melt viscosity in the molten state, has excellent curability, and provides a cured product having excellent mechanical strength, heat resistance, and moisture resistance. The present invention relates to an epoxy resin and a method for producing the same, and further useful for applications such as sealing materials, molding materials, casting materials, laminated materials, composite materials, adhesives, and powder coatings for electrical and electronic parts. An object of the present invention is to provide a curable epoxy resin composition containing an epoxy resin as a main component and a cured product thereof.

As a result of intensive studies to solve the above-mentioned problems, the present inventors can maintain a solid state because an epoxy resin having a specific chemical structure is crystalline at room temperature, and has a very low viscosity above the melting point. And the curable epoxy resin composition using the novel epoxy resin was found to be excellent in curability and give a cured product excellent in mechanical strength, heat resistance and moisture resistance, and completed the present invention. .
That is, the present invention includes, among the following inventions , a novel crystalline epoxy resin represented by the general formula (I), a curable epoxy resin composition containing the crystalline epoxy resin as an epoxy resin component, and the The present invention relates to an invention of a cured product obtained by curing a curable epoxy resin composition .
“A crystalline epoxy resin represented by the general formula (I).
Formula (I)

（Ｉ）

（ただし、Ｒ^１〜Ｒ^１０は水素原子または炭素数１〜６までのアルキル基を示す。ｎは０以上の整数を示す。）
（２）（１）項に記載されたエポキシ化合物であって、一般式（Ｉ）の、Ｒ^１〜Ｒ^１０が水素原子、またはＲ^３、Ｒ^４がメチル基かつ他のＲが水素原子である、結晶性エポキシ樹脂。
（３）一般式（ＩＩ）で表されるジヒドロアントラハイドロキノン化合物をエピハロヒドリンと反応させることを特徴とする（１）項に記載された結晶性エポキシ樹脂の製造方法。
一般式（ＩＩ）

(I)

(However, R < ¹ > -R < ¹⁰ > shows a hydrogen atom or a C1-C6 alkyl group. N shows an integer greater than or equal to 0.)
(2) The epoxy compound described in the item (1) , wherein R ^{1 to} R ^{10 in} the general formula (I) are a hydrogen atom, or R ³ and R ⁴ are a methyl group and the other R is a hydrogen atom. There is a crystalline epoxy resin .
(3) The method for producing a crystalline epoxy resin according to item (1), wherein the dihydroanthrahydroquinone compound represented by the general formula (II) is reacted with epihalohydrin.
Formula (II)

（ただし、Ｒ^１〜Ｒ^１０は水素原子または炭素数１〜６までのアルキル基を示す。）
（４）（３）項に記載された結晶性エポキシ樹脂の製造方法であって、一般式（ＩＩ）の、Ｒ^１〜Ｒ^１０が水素原子、またはＲ^３、Ｒ^４がメチル基かつ他のＲが水素原子である、ジヒドロアントラハイドロキノン化合物をエピハロヒドリンと反応させることを特徴とする、結晶性エポキシ樹脂の製造方法。
（５）一般式（ＩＩＩ）で表される、ジヒドロアントラハイドロキノン化合物のアルカリ金属塩物をエピハロヒドリンと反応させることを特徴とする、（１）項に記載された結晶性エポキシ樹脂の製造方法。
一般式（ＩＩＩ）

(However, R < ¹ > -R < ¹⁰ > shows a hydrogen atom or a C1-C6 alkyl group.)
(4) A method for producing a crystalline epoxy resin according to item (3) , wherein R ^{1 to} R ^{10 in} formula (II) are hydrogen atoms, or R ³ and R ⁴ are methyl groups and other A method for producing a crystalline epoxy resin , comprising reacting a dihydroanthrahydroquinone compound in which R is a hydrogen atom with an epihalohydrin.
(5) The method for producing a crystalline epoxy resin according to (1) , wherein an alkali metal salt of a dihydroanthrahydroquinone compound represented by the general formula (III) is reacted with epihalohydrin.
Formula (III)

（ＩＩＩ）

（ただし、Ａはカリウム原子またはナトリウム原子を示し、Ｒ^１〜Ｒ^１０は水素原子または炭素数１から６までのアルキル基を示す。）
（６）（５）項に記載された結晶性エポキシ樹脂の製造方法であって、一般式（ＩＩＩ）において、Ｒ^１〜Ｒ^１０が水素原子である、またはＲ^３、Ｒ^４がメチル基かつ他のＲが水素原子である、ジヒドロアントラハイドロキノン化合物のアルカリ金属塩物をエピハロヒドリンと反応させることを特徴とする、結晶性エポキシ樹脂の製造方法。
（７）一般式（ＩＩＩ）で表される、ジヒドロアントラハイドロキノン化合物のアルカリ金属塩物をエピハロヒドリンと反応させてエポキシ化合物を製造するにあたり、ジヒドロアントラハイドロキノン化合物のアルカリ金属塩物を水溶液として反応系内に供給する、（５）項に記載された結晶性エポキシ樹脂の製造方法。
（８）エピハロヒドリンと反応させるジヒドロアントラハイドロキノン化合物のアルカリ金属塩水溶液濃度５〜５０重量％である、（７）項に記載された結晶性エポキシ樹脂の製造方法。
（９）ジヒドロアントラハイドロキノン化合物１モルに対し、エピハロヒドリンを４〜４０モル使用して均一な溶液とし、これにジヒドロアントラハイドロキノン化合物１モル当たり１．８〜５モルのアルカリ金属水酸化物を加えて反応させる、（３）項〜（８）項のいずれか１項に記載された結晶性エポキシ樹脂の製造方法。
（１０）（ａ）分子中２個以上のエポキシ基を有するエポキシ樹脂、（ｂ）硬化剤、及び（ｃ）硬化促進剤を必須成分とする硬化性エポキシ樹脂組成物であり、（ａ）のエポキシ樹脂中に、（１）項又は（２）項に記載されたエポキシ化合物を５〜１００質量％含む、硬化性エポキシ樹脂組成物。
（１１）（１０）項に記載された硬化性エポキシ樹脂組成物を硬化させた硬化体。」

(III)

(Where, A is indicated potassium atom or sodium atom, R ¹ to R ¹⁰ represents an alkyl group having a hydrogen atom or 1 to 6 carbon atoms.)
(6) A method for producing a crystalline epoxy resin according to item (5) , wherein in general formula (III), R ^{1 to} R ¹⁰ are hydrogen atoms, or R ³ and R ⁴ are methyl groups and A method for producing a crystalline epoxy resin , comprising reacting an alkali metal salt of a dihydroanthrahydroquinone compound, wherein R is a hydrogen atom, with an epihalohydrin.
(7) In producing an epoxy compound by reacting an alkali metal salt of a dihydroanthrahydroquinone compound represented by the general formula (III) with an epihalohydrin, the alkali metal salt of the dihydroanthrahydroquinone compound is used as an aqueous solution in the reaction system. The method for producing a crystalline epoxy resin according to item (5) .
(8) The method for producing a crystalline epoxy resin according to (7) , wherein the concentration of the dihydroanthrahydroquinone compound to be reacted with the epihalohydrin is an aqueous alkali metal salt concentration of 5 to 50% by weight.
(9) To 1 mol of dihydroanthrahydroquinone compound, 4 to 40 mol of epihalohydrin is used to obtain a uniform solution, and 1.8 to 5 mol of alkali metal hydroxide is added to 1 mol of dihydroanthrahydroquinone compound. The method for producing a crystalline epoxy resin according to any one of (3) to (8) .
(10) A curable epoxy resin composition comprising (a) an epoxy resin having two or more epoxy groups in the molecule, (b) a curing agent, and (c) a curing accelerator; A curable epoxy resin composition containing 5 to 100% by mass of the epoxy compound described in the item (1) or (2) in the epoxy resin.
(11) A cured product obtained by curing the curable epoxy resin composition described in (10) . "

The epoxy resin of the present invention is crystalline and is excellent in handleability because it is solid at room temperature, and has an extremely low melt viscosity in a melted state. Since the curable epoxy resin composition using the epoxy resin is excellent in curability, also provide mechanical strength, heat resistance and moisture resistance excellent cured body, a sealing material for electric and electronic parts, molding materials, Useful in applications such as casting materials, laminate materials, composite materials, adhesives and powder coatings.

The epoxy resin of the present invention represented by the general formula (I) can be obtained by reacting a dihydroanthrahydroquinone compound represented by the general formula (II) with an epihalohydrin in the presence of an alkali metal hydroxide. . For example, it is dissolved in an amount of epihalohydrin corresponding to 4 to 40 moles per mole of dihydroanthrahydroquinone compound under an inert gas stream to obtain a uniform solution. Next, while stirring the solution, an alkali metal hydroxide in an amount of 1.8 to 5 moles per mole of the dihydroanthrahydroquinone compound is added as a solid or an aqueous solution to react. This reaction can be carried out under normal pressure or reduced pressure, and the reaction temperature is usually 30 to 120 ° C. in the case of reaction under normal pressure, and 30 to 80 ° C. in the case of reaction under reduced pressure. In the reaction, the reaction liquid is azeotroped while maintaining a predetermined temperature as required, the condensed liquid obtained by cooling the vaporized vapor is separated into oil / water, and the oil component excluding moisture is returned to the reaction system. Can be dehydrated. Addition of the alkali metal hydroxide is intermittently or continuously added little by little over 1 to 8 hours in order to suppress a rapid reaction. The total reaction time is usually 1 to 10 hours. In addition, it is desirable that the inside of the system is an inert gas atmosphere until the reaction is completed. The inert gas here refers to, for example, nitrogen, argon or the like.

In the production of the novel epoxy resin of the present invention, in order to achieve both crystallinity and low viscosity, which are the features of the present invention, the molar ratio of epihalohydrin to dihydroanthrahydroquinone compound can be controlled, for example. The molar ratio of epihalohydrin to 1 mol of dihydroanthrahydroquinone compound is preferably 4 to 40 mol, more preferably 8 to 20 mol. If this molar ratio is lower than 4, the melt viscosity of the epoxy compound increases, and if it is higher than 40, the viscosity of the epoxy compound does not decrease any more, and it takes time to distill off the unreacted epihalohydrin, which is inefficient. .
After completion of the reaction, or excluded was filtered off by-product salt insoluble is removed by washing with water, excluding epihalohydrin unreacted was distilled off under reduced pressure, the epoxy resins of interest are obtained.
Epichlorohydrin or epibromohydrin is usually used as the epihalohydrin in this reaction. As the alkali metal hydroxide, sodium hydroxide or potassium hydroxide is usually used.

In this reaction, quaternary ammonium salts such as tetramethylammonium chloride and tetraethylammonium bromide; tertiary amines such as benzyldimethylamine and 2,4,6-tris (dimethylaminomethyl) phenol; 2-ethyl Catalysts such as imidazoles such as -4-methylimidazole and 2-phenylimidazole; phosphonium salts such as ethyltriphenylphosphonium iodide; phosphines such as triphenylphosphine may be used.
Further, in this reaction, alcohols such as ethanol and 2-propanol; ketones such as acetone and methyl ethyl ketone; ethers such as dioxane and ethylene glycol dimethyl ether; glycol ethers such as methoxypropanol; non-dimethyls such as dimethyl sulfoxide and dimethylformamide An inert organic solvent such as a protic polar solvent may be used alone or in combination of two or more.
Further, when the saponifiable halogen content of the epoxy compound obtained as described above is too large, a purified epoxy resin having a sufficiently reduced saponifiable halogen content can be obtained by reprocessing. That is, the crude epoxy resin is redissolved in an inert organic solvent such as 2-propanol, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, dioxane, methoxypropanol, dimethyl sulfoxide, and the alkali metal hydroxide is dissolved in a solid or aqueous solution. In addition, after re-ringing reaction at a temperature of about 30 to 120 ° C. for 0.5 to 8 hours, excess alkali metal hydroxide or by-product salt is removed by a method such as washing with water, and the organic solvent is distilled under reduced pressure. When removed, a purified epoxy resin is obtained.

The epoxy resin of the present invention can also be produced by reacting a preliminarily prepared alkali metal salt of a dihydroanthrahydroquinone compound with epihalohydrin. In this case, the alkali metal salt of the dihydroanthrahydroquinone compound is added to the epihalohydrin as it is or in an aqueous solution, but in order to prevent a rapid reaction, it is desirable to add it into the system in small portions.
In addition, when supplied as an aqueous solution, in order to sufficiently advance the ring-closing reaction, after removing water in the system on the way, an alkali metal hydroxide may be added in solid or aqueous solution to increase the epoxidation rate. desirable.
Moreover, the density | concentration of the alkali metal salt aqueous solution of the dihydroanthrahydroquinone compound is 5-50 mass%, Preferably it is 15-30 mass%. When the concentration is lower than 5% by mass, the amount of water brought into the system increases, which may inhibit the progress of the epoxidation reaction. If it is more than 50% by mass, the fluidity of the aqueous solution is lowered, and there is a possibility that the piping of the apparatus may be clogged.
Moreover, the alkali metal salt aqueous solution of a dihydroanthrahydroquinone compound can contain an alkali metal hydroxide in an equivalent amount or more necessary for forming a salt for stabilization. In addition, other organic solvents such as alcohols may be added to the aqueous solution as long as the stability is not impaired.
Even when an alkali metal salt of a dihydroanthrahydroquinone compound or an aqueous solution thereof is used as a starting material, an epoxy resin is obtained using various conditions, various reaction catalysts, various organic solvents and operations similar to the epoxidation reaction of the dihydroanthrahydroquinone compound. be able to. The above-described method can also be used when a crude epoxy resin is used as a purified epoxy resin .

Usually, the reaction solvent is distilled off at a temperature close to or above the melting point of the epoxy resin , so that the epoxy resin immediately after the solvent is distilled off is in a molten state. A method for crystallizing the molten epoxy resin to form a solid is not particularly specified, and a known method can be used. For example, a method of extracting a molten epoxy resin at a high temperature into a vat or the like, and solidifying the crystal by natural cooling, and a method of adding a small amount of the crystalline solid of the epoxy resin prepared in advance as a crystal nucleus to promote crystallization , A method of promoting crystallization by stirring molten epoxy resin or applying vibration, a method of extracting while applying a strong external force with a kneader, etc., promoting crystallization while controlling the temperature so as not to overcool The method etc. are raised, These methods can be performed individually or in combination of two or more. It is desirable from the viewpoint of productivity that the novel epoxy resin of the present invention is also operated as described above to promote crystallization.
Moreover, for further low viscosity and high purity of the epoxy resin, it may be recrystallized from an appropriate solvent the crude epoxy resin or purified epoxy resin obtained by the reaction.

In the dihydroanthrahydroquinone compound used in the above reaction, in the general formula (II), the substituents R ^{1 to} R ¹⁰ are a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Of these, R ^{1 to} R ¹⁰ are preferably hydrogen atoms or methyl groups, and particularly preferably R ^{1 to} R ¹⁰ are all hydrogen atoms (1,4 dihydroanthrahydroquinone). The epoxy resin obtained from this is crystalline having a temperature of 80 to 120 ° C., and melts rapidly at a temperature equal to or higher than the melting point and has an extremely low viscosity.
Further, when an alkali metal salt of a dihydroanthrahydroquinone compound is used for the reaction, in the same manner as described above, in the general formula (III), the substituents R ^{1 to} R ¹⁰ are a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, Among them, R ^{1 to} R ¹⁰ are preferably hydrogen atoms or methyl groups, and particularly preferably R ^{1 to} R ¹⁰ are all hydrogen atoms (alkali metal salt of 1,4-dihydroanthrahydroquinone).
Examples of the alkali metal that forms a salt include potassium and sodium, and in general, as a hydroxide (potassium hydroxide or sodium hydroxide), as it is or in a form dissolved in a solvent such as water or alcohol. Supplied.

A known method can be used as a method for producing a dihydroanthrahydroquinone compound, which is a raw material for the novel epoxy resin of the present invention. For example, 1,4,4a, 9a-tetrahydroanthraquinone obtained by Diels-Alder reaction between 1,4-naphthoquinone and butadiene is used as an aromatic hydrocarbon such as benzene or xylene as a solvent, and paratoluenesulfonic acid as a catalyst. And a method of obtaining crystals by cooling after isomerization reaction at 80 to 100 ° C. for 30 minutes to 3 hours (Japanese Patent Laid-Open No. 54-122263).
Similarly, a known method can be used as a method for producing an alkali metal salt of a dihydroanthrahydroquinone compound. For example, a method obtained by dissolving the dihydroanthrahydroquinone compound obtained by the above method in an aqueous solution in which at least an equivalent amount (2 mol of the dihydroanthrahydroquinone compound) of an alkali metal hydroxide is dissolved, or 1,4-naphthoquinone and butadiene Contact with an aqueous solution in which at least an equivalent amount of 1,4,4a, 9a-tetrahydroanthraquinone obtained by Diels-Alder reaction with Alkali metal hydroxide is dissolved (2 mol times that of 1,4,4a, 9a-tetrahydroanthraquinone) By doing so, 1,4,4a, 9a-tetrahydroanthraquinone isomerizes and can be obtained as an aqueous solution of an alkali metal salt of a dihydroanthrahydroquinone compound. In addition, an aqueous solution of disodium salt of 1,4-dihydroanthrahydroquinone in which R ^{1 to} R ¹⁰ are hydrogen atoms in the above general formula (III) has already been widely used in the world for applications such as pulp cooking aids. This can be used as it is.

The curable epoxy resin composition of the present invention comprises (a) an epoxy resin having two or more epoxy groups in one molecule, (b) a curing agent, and (c) a curing accelerator as essential components. This epoxy resin is characterized by including the novel epoxy resin of the present invention. In addition, (a) In addition to the novel epoxy resin of the present invention, an epoxy resin having two or more epoxy groups in one molecule can be used in combination, and a known epoxy resin can be used as the epoxy resin. Can do. For example, bisphenol A type, bisphenol F type, biphenyl type, tetramethylbiphenyl type, cresol novolak type, phenol novolak type, bisphenol A novolak type, dicyclopentadiene phenol condensation type, phenol aralkyl condensation type, etc. Epoxy resins and aliphatic epoxy resins can be raised. These epoxy resins can be used alone or in combination of two or more, but the amount of the epoxy resin of the present invention is 5 to 100% by mass in the whole epoxy resin. When the blending amount is lower than 5% by mass, the effect of the present invention is not sufficiently exhibited.

(B) The curing agent is not particularly specified, and a known epoxy resin curing agent can be used. Examples of these epoxy resin curing agents include polyphenols such as bisphenol A, bisphenol F, bisphenol S, thiodiphenol, hydroquinone, resorcin, biphenol, tetramethylbiphenol, dihydroxynaphthalene, dihydroxydiphenyl ether, phenol novolac resins, Cresol novolak resin, bisphenol A novolak resin, naphthol novolak resin, phenol resin obtained by condensation reaction of various phenols with various aldehydes such as benzaldehyde, hydroxybenzaldehyde, crotonaldehyde, glyoxal, etc., phenol aralkyl resin, phenol modification Various phenols such as xylene resin, phenol terpene resin, dicyclopentadiene phenol resin Active ester compounds obtained by esterification such as benzoate or acetate conversion of all or part of phenolic hydroxyl groups of resins and various phenols (resins), methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, pyromellitic anhydride Examples thereof include acid anhydrides such as acid and methyl nadic acid, and amines such as diethylenetriamine, isophorodiamine, diaminodiphenylmethane, diaminodiphenylsulfone, and dicyandiamide. The curing agent may be used alone or in combination of two or more. The amount of the curing agent used is such that (a) 1 mol of the epoxy group in all components of the epoxy resin is 0.5 to 2.0 mol of a group that reacts with the epoxy group in the entire curing agent. Is preferable, and more preferably 0.7 to 1.2 mol.

(C) There is no designation | designated as a hardening accelerator in particular, A well-known hardening accelerator can be used. Examples of the curing accelerator include phosphine compounds such as tributylphosphine, triphenylphosphine, tris (dimethoxyphenyl) phosphine, tris (hydroxypropyl) phosphine, tris (cyanoethyl) phosphine, tetraphenylphosphonium tetraphenylborate, methyltributylphosphonium tetra. Phosphonium salts such as phenylborate, 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-undeci Imidazoles such as imidazolyl- (1)]-ethyl-s-triazine, 1-cyanoethyl-2-undecylimidazolium trimellitate, 2-methylimidazolium isocyanurate, 2-ethyl-4-methylimidazolium tetraphenyl Borate, imidazolium salts such as 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, 11,5-diazabicyclo [5,4,0] -7-undecene, 1,5-diazabicyclo [4,3, 0] -5-no Emissions, 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, phosphine compounds, imidazole compounds, diazabicyclo compounds, and salts thereof are preferable. These curing accelerators are used alone or in combination of two or more, and the amount used is 0.1 to 7% by mass relative to the total epoxy compound.

In addition, the epoxy resin curable resin composition of the present invention appropriately includes a filler, a coupling agent, a flame retardant, a flame retardant aid, a plasticizer, a solvent, a reactive diluent, a pigment, and the like. Can be blended.
The curable epoxy resin composition of the present invention may be prepared by using a method similar to a conventionally known method, as long as all compounding components such as an epoxy resin, a curing agent, and a curing accelerator are uniformly mixed. It can be a thing. Examples of the method include melt kneading using a kneader, roll or extruder, and dry blending in which powdery components are mixed. The composition thus obtained may be pulverized or classified as necessary.
Also, the curable epoxy resin composition of the present invention can be dissolved in a solvent such as acetone, methyl ethyl ketone, methyl cellosolve, dimethylformamide, toluene, xylene, etc. to obtain a varnish-like composition. A cured product can be obtained by hot press-molding a prepreg obtained by impregnating a base material such as glass fiber, carbon fiber, polyester fiber, polyamide fiber, paper, and the like, followed by heating and drying.
The cured product of the present invention can be obtained by thermally curing the curable epoxy resin composition of the present invention, and is in the form of a molded product, a laminate, a cast product, an adhesive, a coating film, a film and the like. For example, when the form is a molded product, the cured product can be obtained by heating the composition at 30 to 250 ° C. for 30 seconds to 10 hours using a casting, transfer molding machine, injection molding machine or the like. In the case of a varnish, a cured product can be obtained by hot press-molding a prepreg formed by impregnating a base material such as glass fiber, carbon fiber, polyester fiber, polyamide fiber, paper, and the like, followed by heat drying.
As described above, the novel epoxy resin of the present invention is solid at room temperature, has excellent handleability, has an extremely low melt viscosity in a molten state, and has excellent curability. Curability using this resin Epoxy resin composition can give a cured product with excellent mechanical strength, heat resistance and moisture resistance, so it can be used as a sealing material, molding material, casting material, laminate material, composite material, adhesive for electrical and electronic parts. And useful for applications such as powder coatings.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these Examples, unless the summary is exceeded.
(Example 1)
Epichlorohydrin (1050 g) and 2-propanol (410 g) were charged into a 3 L four-necked flask equipped with a stirrer, a reflux condenser and a thermometer, and the system was purged with nitrogen under reduced pressure. To this, 200 g of 1,4-dihydroanthrahydroquinone was added in a nitrogen atmosphere, and the mixture was heated to 40 ° C. and dissolved uniformly. Then, 180 g of a 48.5 mass% sodium hydroxide aqueous solution was added dropwise over 90 minutes. During this time, the temperature was gradually raised, and the temperature inside the system was adjusted to 65 ° C. after the dropping was completed.
Thereafter, the reaction was completed by maintaining at 65 ° C. for 30 minutes, and by-product salt and excess sodium hydroxide were removed by washing with water. Subsequently, excess epichlorohydrin and 2-propanol were distilled off from the product under reduced pressure to obtain a crude epoxy resin mixture.
This crude epoxy resin mixture was dissolved in 460 g of methyl isobutyl ketone, 7 g of a 48.5 mass% sodium hydroxide aqueous solution was added, and the mixture was reacted at a temperature of 65 ° C. for 1 hour. Thereafter, an aqueous sodium hydrogen phosphate solution was added to the reaction solution to neutralize excess sodium hydroxide, followed by washing with water to remove by-product salts. The temperature was controlled so that the liquid temperature was 65 to 90 ° C. during washing with water. Subsequently, after methyl isobutyl ketone was completely removed under heating and reduced pressure, the resinous material in a molten state was taken out into a vat, stirred for 10 times with a glass rod, and then naturally cooled at room temperature. About 2 hours later, the whole crystallized and was taken out to obtain 285 g of a yellow crystalline epoxy resin . The obtained epoxy resin had an epoxy equivalent of 176 g / eq, hydrolyzable chlorine of 450 ppm, a melt viscosity at 150 ° C. of 16 mPa · s, and a melting point of 104 ° C. by DSC measurement. It was solid at room temperature and the handleability was good. H-NMR spectrum of the obtained epoxy resin is shown in FIG. 1-1, and attribution of each peak is shown in Table 1. The IR spectrum of the obtained epoxy resin is shown in FIG. From the above, it was confirmed that an epoxy resin represented by the chemical formula (IV) and having n = 0.1 (from GPC) was obtained.
Chemical formula (IV)

（ＩＶ）

図１は、実施例１で得られた樹脂のＨ−ＮＭＲスペクトルを示す。

(IV)

FIG. 1 shows the H-NMR spectrum of the resin obtained in Example 1.

式Ｖ

Formula V

（Ｖ）

図２に、実施例１で得られた樹脂のＩＲスペクトルを示す。

(V)

FIG. 2 shows the IR spectrum of the resin obtained in Example 1.

(Example 2)
In Example 1, instead of 200 g of 1,4-dihydroanthrahydroquinone, 225 g of 1,4-dihydro-2,3-dimethylanthrahydroquinone was used, and the same operation as in Example 1 was performed, which is represented by the chemical formula (V). An epoxy resin 306 g was obtained. The obtained epoxy resin had an epoxy equivalent of 194 g / eq, hydrolyzable chlorine of 435 ppm, a melt viscosity at 150 ° C. of 17 mPa · s, and a melting point of 94 ° C. by DSC measurement. From GPC, n = 0.1 in the chemical formula (VI). At room temperature, it was a yellow crystalline solid and handleability was good.
Chemical formula (VI)

（ＶＩ）

(VI)

(Example 3)
Epichlorohydrin (1050 g) and 2-propanol (410 g) were charged into a 3 L four-necked flask equipped with a stirrer, a reflux condenser and a thermometer, and the system was purged with nitrogen under reduced pressure to maintain the temperature at 40 ° C. Under a nitrogen atmosphere, 900 g of a 28% by mass aqueous solution of 1,4-dihydroanthrahydroquinone sodium salt was added dropwise thereto over 90 minutes. During this period, the temperature was gradually raised, and the temperature was controlled so that the temperature inside the system was 65 ° C. after the completion of the dropping. Thereafter, after holding at 65 ° C. for 30 minutes, water containing secondary salts was discharged by liquid-liquid separation. Next, while maintaining the system at 65 ° C., 32 g of a 48.5 mass% sodium hydroxide aqueous solution was dropped over 15 minutes, and then the reaction was completed over 30 minutes. Thereafter, secondary salts were removed by washing with water, and excess epichlorohydrin and 2-propanol were distilled off from the product under reduced pressure to obtain a crude epoxy resin mixture.
This crude epoxy resin mixture was dissolved in 460 g of methyl isobutyl ketone, 7 g of 48.5 mass% sodium hydroxide aqueous solution was added, and the mixture was reacted at a temperature of 65 ° C. for 1 hour. Thereafter, an aqueous sodium hydrogen phosphate solution was added to the reaction solution to neutralize excess sodium hydroxide, followed by washing with water to remove by-product salts. Subsequently, after methyl isobutyl ketone was completely removed under heating and reduced pressure, the resinous material in a molten state was taken out into a vat, stirred with a glass rod ten times, and then naturally cooled at room temperature. About 2 hours later, the whole crystallized and was taken out to obtain 290 g of a yellow crystalline epoxy resin . The epoxy resin thus obtained had an epoxy equivalent of 174 g / eq, hydrolyzable chlorine of 390 ppm, a melt viscosity at 150 ° C. of 15 mPa · s, a melting point by DSC measurement of 106 ° C., a solid at room temperature and good handleability. . The obtained epoxy resin has almost the same H-NMR and IR spectra as the epoxy compound obtained in Example 1, and is represented by the chemical formula (IV), and n = 0.08 (from GPC). It was confirmed that a resin was obtained.

Examples 4-6
Using the epoxy resins obtained in Examples 1 to 3, phenol novolak resin (softening point 84 ° C., hydroxyl group equivalent 103 g / eq) and phenol aralkyl resin (softening point 83 ° C., hydroxyl group equivalent 175 g / eq) as a curing agent A fixed amount was melt-mixed at 120 ° C. in a glass beaker, and a composition obtained by adding and mixing a predetermined amount of triphenylphosphine as a curing accelerator was cast, and aftercured at 175 ° C. for 7 hours. Cured product was obtained. Various physical properties of the obtained cured product are shown in Table 2.

Comparative Examples 1 and 2
In Example 4, in place of the epoxy resin obtained in Example 1, bisphenol A type epoxy resin (liquid at normal temperature, viscosity at 150 ° C. is 10 mPa · s), tetramethyl biphenol type epoxy resin (melting point 105 ° C., 150 ° C. Table 2 shows the results of measuring the cured properties by obtaining a cured product in the same manner as in Example 4 using a viscosity of 15 mPa · s).
As described above, the epoxy resin of the present invention was a crystalline resin, and was excellent in handleability because it was solid at room temperature, and had a very low viscosity in the molten state. Moreover, the result that the curable epoxy resin composition using the epoxy resin gave the hardened | cured material excellent in sclerosis | hardenability, mechanical strength, heat resistance, and moisture resistance was obtained.

（＊１）熱板法，１７５℃
（＊２）ＴＭＡを用いて測定した。
（＊３）ＪＩＳ Ｋ６９１１に従ってテストを行った。
（＊４）８５℃、８５％ＲＨ７２ｈｒ後の吸湿率。

(* 1) Hot plate method, 175 ° C
(* 2) Measured using TMA.
(* 3) A test was performed according to JIS K6911.
(* 4) Moisture absorption after 85 ° C. and 85% RH 72 hours.

The epoxy resin of the present invention has crystallinity and is easy to handle because it is solid at room temperature, and has a low melt viscosity. A composition using this has excellent curability, mechanical strength, heat resistance, and moisture resistance. Since it provides a cured product having excellent properties, it is useful for sealing materials, molding materials, adhesives, paints, and the like.

2 is a chart showing an H-NMR spectrum of the epoxy resin obtained in Example 1. FIG. 2 is a chart showing an IR spectrum of the epoxy compound obtained in Example 1. FIG.

Claims (4)

A crystalline epoxy resin represented by the general formula (I).
Formula (I)

(I)

(However, R ^{1 to} R ¹⁰ represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. N represents an integer of 0 or more.) 2. The crystalline epoxy resin according to claim 1, wherein R ^{1 to} R ¹⁰ of the general formula (I) are a hydrogen atom, or R ³ and R ⁴ are a methyl group and the other R is a hydrogen atom. Crystalline epoxy resin . (A) An epoxy resin having two or more epoxy groups in one molecule, (b) a curing agent, and (c) a curable epoxy resin composition containing a curing accelerator as essential components, and the epoxy resin of (a) A curable epoxy resin composition containing 5 to 100% by mass of the crystalline epoxy resin according to claim 1 or 2.   A cured product obtained by curing the curable epoxy resin composition according to claim 3.

Images