Epoxy resin composition and cured epoxy resin

Abstract

To provide a cured epoxy resin that is excellent in all of heat resistance, repairability and re-moldability.SOLUTION: An epoxy resin composition comprises: a curing agent comprising one Diels-Alder reaction unit composed of an anthracene structure and a maleimide structure in each molecule, with the Diels-Alder reaction unit comprising at least two phenolic hydroxy groups; and an epoxy resin. The content of the curing agent relative to the total mass of the epoxy resin and the curing agent is 0.10 mmol / g or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an epoxy resin composition and a cured epoxy resin product. [Background technology]

[0002] Epoxy resins form highly cross-linked network polymers through cross-linking reactions with curing agents, resulting in a cured product (cured epoxy resin).Cured epoxy resins have excellent heat resistance, mechanical strength, adhesive properties, and electrical insulation, and are used in a variety of fields, including electrical and electronic materials, adhesives, paints, and construction and civil engineering materials.

[0003] On the other hand, a common issue with cured epoxy resins is their low long-term reliability. Furthermore, because the network structure of cured epoxy resins is formed by covalent bonds, they are insoluble and infusible, making them difficult to reshape by heating or solvent treatment. This makes them difficult to recycle or reuse, posing challenges in terms of waste reduction and environmental impact. Furthermore, if the microcracks that form within cured epoxy resins could be repaired, it would be expected that the brittleness of cured thermosetting resins could be improved. However, due to the infusibility of the network structure, repair by heating is difficult.

[0004] To address these issues, a cured epoxy resin is known that uses a diamine containing a site where furan and maleimide are bonded via the Diels-Alder reaction as a curing agent (Non-Patent Document 1). When heated, the crosslinked structure of this cured epoxy resin decrosslinks via a retro-Diels-Alder reaction, and when the temperature is lowered, it recrosslinks via the Diels-Alder reaction. This reversible decrosslinking and recrosslinking imparts thermoreversibility to the network structure, making it possible to reshape or repair it by heating. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-306837 [Non-patent literature]

[0006] [Non-Patent Document 1] X.Kuang, G.Liu, X.Dong, X.Liu, J.Xu, D.Wang, J.Polym.Sci., Part A: Polym.Chem,. 53, 2094(2015). Summary of the Invention [Problem to be solved by the invention]

[0007] However, the Diels-Alder reaction product of furan and maleimide undergoes a retro-Diels-Alder reaction at around 120°C, causing the cured epoxy resin to decrosslink above 120°C. Therefore, cured epoxy resins produced by the Diels-Alder reaction of furan and maleimide are not suitable for applications above 120°C. In addition, active research has been conducted into the use of reversible bonds such as dynamic covalent bonds and supramolecular bonds to impart repairability and remoldability to cured epoxy resins, but these generally still have issues such as thermal decomposition.

[0008] Patent Document 1 also discloses a compound having one addition reaction moiety in the molecule formed by a Diels-Alder reaction from a conjugated diene structure having a phenolic hydroxyl group and a dienophilic structure having a phenolic hydroxyl group, wherein the addition reaction moiety has at least one phenolic hydroxyl group in both the structure composed of the conjugated diene structure and the structure composed of the dienophilic structure, and specifically discloses that by using such a compound as part of an epoxy resin composition, a cured product having heat resistance and low elasticity at high temperatures can be obtained. However, there is room for further development in terms of epoxy resin cured products that have both good heat resistance and good repairability.

[0009] In view of the above problems, an object of the present invention is to provide an epoxy resin composition and a cured epoxy resin product that can be produced from an epoxy resin composition having good heat resistance, repairability, and remoldability. [Means for solving the problem]

[0010] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by providing an epoxy resin composition containing a curing agent having a predetermined structure at a predetermined concentration, or a cured epoxy resin product using the epoxy resin composition.

[0011] In one aspect, the present invention provides an epoxy resin composition comprising: a curing agent having one Diels-Alder reaction unit, which is composed of an anthracene structure and a maleimide structure, in the molecule, and the Diels-Alder reaction unit having at least two phenolic hydroxyl groups; and an epoxy resin, wherein the concentration of the curing agent relative to the total mass of the epoxy resin and the curing agent is 0.10 mmol / g or more.

[0012] In one embodiment of the epoxy resin composition of the present invention, the curing agent is represented by the following formula (1): [ka] (In formula (1), R 1 ~R 11 are each independently a hydrogen atom, a halogen atom, a hydroxy group, an alkoxy group, an aralkyloxy group, an aryloxy group, a nitro group, an amino group, an amido group, a carboxy group, an alkyloxycarbonyl group, an aryloxycarbonyl group, a cyano group, an alkyl group, a cycloalkyl group, an aralkyl group, or an aryl group, and R 1 ~R 11 At least one of the groups is a functional group containing a phenolic hydroxyl group or a group having a phenolic hydroxyl group as a substituent.

[0013] In another embodiment of the epoxy resin composition of the present invention, the curing agent is represented by the following formula (2): [ka]

[0014] In another embodiment of the epoxy resin composition of the present invention, the curing agent is represented by the following formula (3): [ka]

[0015] In yet another embodiment of the epoxy resin composition of the present invention, the epoxy resin is represented by the following formula (4) and has an epoxy equivalent of 500 to 10,000 g / eq. [ka] In formula (4), each Ar independently represents a structure having an unsubstituted or substituted aromatic ring, X is a structural unit represented by the following formula (4-1), and Y is a structural unit represented by the following formula (4-2), [ka] [In formulas (4-1) and (4-2), each Ar independently represents a structure having an unsubstituted or substituted aromatic ring, R 1 , R 2 are each independently a hydrogen atom, a methyl group, or an ethyl group, R' is a divalent hydrocarbon group having 2 to 12 carbon atoms; R 3 , R 4 , R 7 , R 8 each independently represents a hydroxyl group, a glycidyl ether group, or a 2-methylglycidyl ether group, R 5 , R 6 , R 9 , R 10 are each independently a hydrogen atom or a methyl group, n1 is an integer of 4 to 16, and n2 is the average number of repeating units and is 2 to 30. R11 , R 12 are each independently a glycidyl ether group or a 2-methylglycidyl ether group, R 13 , R 14 each independently represents a hydroxyl group, a glycidyl ether group, or a 2-methylglycidyl ether group, R 15 , R 16 is a hydrogen atom or a methyl group, m1, m2, p1, p2, q are the mean values ​​of the repetitions, m1 and m2 each independently represent 0 to 25, and m1+m2≧1; p1 and p2 each independently represent a number from 0 to 5; q is between 0.5 and 5. However, the bond between the structural unit X represented by the formula (4-1) and the structural unit Y represented by the formula (4-2) may be random or block, and the total number of the structural units X and Y present in one molecule is m1 and m2, respectively.

[0016] In yet another embodiment of the epoxy resin composition of the present invention, the epoxy resin is represented by the following formula (5): [ka] (In formula (5), p1, p2, q, m 2 and n 2 is the average value of the repetitions, and each is independently p1 is 0 to 5, p2 is 0 to 5, q is 0.5 to 5, m 2 is 1 ~25, n 2 is 2 to 30.)

[0017] In another aspect, the present invention relates to a cured epoxy resin product obtained by curing the epoxy resin composition of the present invention. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a cured epoxy resin product that is excellent in heat resistance, repairability, and remoldability.

Embodiments for Carrying out the Invention

[0019] Next, embodiments for carrying out the present invention will be described in detail. It should be understood that the present invention is not limited to the following embodiments, and design changes, improvements, etc. can be appropriately made based on the ordinary knowledge of those skilled in the art without departing from the gist of the present invention.

[0020] (Epoxy Resin Composition) The epoxy resin composition of the present invention has one Diels-Alder reaction unit composed of an anthracene structure and a maleimide structure in the molecule, and the Diels-Alder reaction unit contains a curing agent having at least two phenolic hydroxyl groups (hereinafter, the curing agent is also referred to as "D-A curing agent") and an epoxy resin. <N

[0021] <D-A Curing Agent> The Diels-Alder reaction is an addition reaction between a conjugated diene and a parent diene to form a six-membered ring. Because the Diels-Alder reaction is an equilibrium reaction, a retro-Diels-Alder reaction occurs at a certain temperature, resulting in dissociation (decrosslinking). If the temperature at which the retro-Diels-Alder reaction occurs (dissociation temperature) is low, decrosslinking occurs at higher temperatures, resulting in a decrease in the crosslink density of the cured product and a decrease in mechanical strength. In contrast, DA curing agents contain one Diels-Alder reaction unit consisting of a highly thermally stable anthracene structure and a maleimide structure per molecule. This allows for a high dissociation temperature of 250°C or higher, and they maintain their crosslinked structure at least at around 200°C, resulting in excellent thermal stability. Therefore, using a DA curing agent as an epoxy resin curing agent can suppress a decrease in crosslink density in the cured product (epoxy resin cured product) cured by the reaction of the curing agent with the epoxy resin, thereby maintaining good mechanical strength. Furthermore, it is thought that applying mechanical energy such as scratching or external force to a cured epoxy resin produced with a DA curing agent will break the C-C bond in the Diels-Alder reaction unit, resulting in the formation of anthracene and maleimide at the cut surface. The C-C bond in the Diels-Alder reaction unit has lower bond energy than a normal covalent bond and is therefore more easily broken. In the Diels-Alder reaction between anthracene and maleimide, the equilibrium shifts in the direction of the bond at temperatures below 200°C, so an adduct (Diels-Alder reaction unit) is formed again, making it possible to repair scratches and reshape the resin.

[0022] The DA curing agent in the epoxy resin composition of the present invention has a Diels-Alder reaction unit with at least two phenolic hydroxyl groups. The Diels-Alder reaction unit has at least two phenolic hydroxyl groups, which allows it to react with at least two epoxy groups, improving the crosslink density of the cured product and enabling the production of a cured product with excellent toughness and adhesiveness. As a result, the elastic modulus and glass transition temperature of the cured epoxy resin product are improved.

[0023] The DA curing agent in the epoxy resin composition of the present invention may be represented by the following formula (1): [ka] (In formula (1), R 1 ~R 11 are each independently a hydrogen atom, a halogen atom, a hydroxy group, an alkoxy group, an aralkyloxy group, an aryloxy group, a nitro group, an amino group, an amido group, a carboxy group, an alkyloxycarbonyl group, an aryloxycarbonyl group, a cyano group, an alkyl group, a cycloalkyl group, an aralkyl group, or an aryl group, and R 1 ~R 11 At least one of the groups is a functional group containing a phenolic hydroxyl group or a group having a phenolic hydroxyl group as a substituent.

[0024] R in Equation (1) 1 ~R 11 Regarding the above, the alkoxy group, aralkyloxy group, aryloxy group, carboxy group, alkyloxycarbonyl group, aryloxycarbonyl group, alkyl group, cycloalkyl group, aralkyl group, and aryl group also include those having various substituents bonded to the carbon atoms thereof. For example, R in formula (1) 1 ~R 11 The aryl group includes an aminoaryl group in which an amino group is further bonded to a carbon atom. 1 ~R 11 When at least one of the above is a "group having a phenolic hydroxyl group as a substituent," an example of the group is a hydroxyaryl group (an aryl group having a phenolic hydroxyl group as a substituent).

[0025] The DA curing agent in the epoxy resin composition of the present invention may be represented by the following formula (2): [ka]

[0026] The DA curing agent in the epoxy resin composition of the present invention may be represented by the following formula (3): [ka]

[0027] When the DA curing agent in the epoxy resin composition of the present invention contains a curing agent represented by the above formula (2) or (3), the Diels-Alder reaction unit has three phenolic hydroxyl groups. Therefore, each can react with three epoxy groups, resulting in improved crosslink density and superior toughness and adhesive properties. As a result, the elastic modulus and glass transition temperature of the cured epoxy resin are improved.

[0028] (Method for producing the DA curing agent used in the present invention) The DA curing agent used in the present invention is a compound that has one Diels-Alder reaction unit in the molecule, which is an addition reaction moiety formed by the Diels-Alder reaction of an anthracene structure and a maleimide structure, and the Diels-Alder reaction unit has at least two phenolic hydroxyl groups. The Diels-Alder reaction, in which a conjugated diene such as an anthracene structure and a parent diene such as a maleimide structure undergo an addition reaction to form a six-membered ring, is an equilibrium reaction. It is widely known that at temperatures higher than the temperature at which the addition reaction proceeds, the addition reaction site dissociates, returning the original conjugated diene and parent diene, resulting in a retro-Diels-Alder reaction. The DA curing agent used in the present invention has an anthracene structure having at least one phenolic hydroxyl group and a maleimide structure having at least one phenolic hydroxyl group, and even after the Diels-Alder reaction, two or more phenolic hydroxyl groups derived from each structure remain in the Diels-Alder reaction unit. If each structural unit does not contain a phenolic hydroxyl group that reacts with the epoxy resin, the crosslink density of the resulting cured product will decrease, resulting in poor heat resistance, mechanical properties, and adhesive strength. Furthermore, the structural units dissociated by the retro Diels-Alder reaction will become free, making it difficult for the Diels-Alder reaction units to recombine after dissociation. On the other hand, if each structural unit contains a phenolic hydroxyl group that reacts with the epoxy group, the structural units will be fixed to a certain extent in the cured product, and the structural units will be located in close proximity, allowing for easy recombination. Using this compound in an epoxy resin composition can impart repairability and remoldability to the cured product.

[0029] The compound having an anthracene structure used in the method for producing the DA curing agent of the present invention can include any of the compounds listed in the following formula (10): Among these, a compound having 1 to 2 moles of phenolic hydroxyl groups per mole of anthracene structure is preferred in terms of reactivity with epoxy groups, and a compound having 1 mole of phenolic hydroxyl groups per mole of anthracene structure is particularly preferred in terms of the balance between reactivity, physical properties of the cured product, and repairability and remoldability. [ka]

[0030] The structures of the compounds listed in the formula (10) each independently include a hydrogen atom, a halogen atom, an alkoxy group, an aralkyloxy group, an aryloxy group, a nitro group, an amide group, an alkyloxycarbonyl group, an aryloxycarbonyl group, a cyano group, an alkyl group, a cycloalkyl group, an aralkyl group, or an aryl group as a substituent. Furthermore, in the structures of the compounds listed in the formula (10), the alkoxy group, the aralkyloxy group, the aryloxy group, the carboxy group, the alkyloxycarbonyl group, the aryloxycarbonyl group, the alkyl group, the cycloalkyl group, the aralkyl group, and the aryl group also include those having various substituents further bonded to their carbon atoms. For example, the aryl group includes a hydroxyaryl group in which a phenolic hydroxyl group is further bonded to a carbon atom.

[0031] The compound having a maleimide structure used in the method for producing the DA curing agent of the present invention can be any of the compounds listed in the following formula (11). Among these, monohydroxyphenylmaleimide is particularly preferred in terms of the balance between reactivity, cured product properties, and repairability and remolding ability. Among the monoaminophenylmaleimides, parahydroxyphenylmaleimide is particularly preferred in terms of heat resistance. Among these, compounds having 1 to 2 moles of phenolic hydroxyl groups per mole of maleimide structure are preferred in terms of reactivity with epoxy groups, and compounds having 1 mole of phenolic hydroxyl groups per mole of anthracene structure are particularly preferred in terms of the balance between reactivity, physical properties of the cured product, and repairability and remoldability. [ka]

[0032] The structures of the compounds listed in the above formula (11) each independently include a hydrogen atom, a halogen atom, an alkoxy group, an aralkyloxy group, an aryloxy group, a nitro group, an amide group, an alkyloxycarbonyl group, an aryloxycarbonyl group, a cyano group, an alkyl group, a cycloalkyl group, an aralkyl group, or an aryl group as a substituent. Furthermore, in the structures of the compounds listed in the above formula (11), the alkoxy group, the aralkyloxy group, the aryloxy group, the carboxy group, the alkyloxycarbonyl group, the aryloxycarbonyl group, the alkyl group, the cycloalkyl group, the aralkyl group, and the aryl group also include those having various substituents further bonded to their carbon atoms. For example, the aryl group includes a hydroxyaryl group in which a phenolic hydroxyl group is further bonded to a carbon atom.

[0033] The DA curing agent used in the present invention can be synthesized by subjecting the compound having the anthracene structure and the compound having the maleimide structure to a Diels-Alder reaction, thereby causing an addition reaction between the conjugated diene structure and the parent dien structure. The Diels-Alder reaction can be carried out by a known method. For example, the conjugated diene compound and the parent dien compound are mixed in equimolar amounts, or in some cases, one of the components is mixed in excess, and the mixture is melted by heating or dissolved in a solvent. The mixture is stirred at room temperature to 200°C for 1 to 24 hours, and the resulting mixture can be obtained by filtration or solvent distillation without further purification. Alternatively, the mixture can be obtained by a commonly used isolation and purification method such as recrystallization, reprecipitation, or chromatography.

[0034] <Epoxy resin> The epoxy resin contained in the epoxy resin composition of the present invention may be any commonly known epoxy resin. The epoxy resin contained in the epoxy resin composition of the present invention is not limited in any way and may, for example, be liquid epoxy resins such as bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol AD ​​type epoxy resins, resorcinol type epoxy resins, hydroquinone type epoxy resins, catechol type epoxy resins, dihydroxynaphthalene type epoxy resins, biphenyl type epoxy resins, or tetramethylbiphenyl type epoxy resins; brominated epoxy resins such as brominated phenol novolac type epoxy resins; solid bisphenol A type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins; triphenyl methacrylate type epoxy resins; Examples of epoxy resins include phenol-type epoxy resins, tetraphenylethane-type epoxy resins, dicyclopentadiene-phenol addition reaction-type epoxy resins, phenol aralkyl-type epoxy resins, phenylene ether-type epoxy resins, naphthylene ether-type epoxy resins, naphthol novolac-type epoxy resins, naphthol aralkyl-type epoxy resins, naphthol-phenol co-condensed novolac-type epoxy resins, naphthol-cresol co-condensed novolac-type epoxy resins, aromatic hydrocarbon formaldehyde resin-modified phenolic resin-type epoxy resins, and biphenyl-modified novolac-type epoxy resins. These may be used alone or in combination of two or more, and it is preferable to select and use various types depending on the intended use, the physical properties of the cured product, etc. Among these, from the viewpoint of general industrial availability, it is preferable to use bisphenol-type epoxy resins, novolac-type epoxy resins, etc.

[0035] The epoxy resin contained in the epoxy resin composition of the present invention may be an epoxy resin represented by the following formula (4) and having an epoxy equivalent of 500 to 10,000 g / eq. [ka] In formula (4), each Ar independently represents a structure having an unsubstituted or substituted aromatic ring, X is a structural unit represented by the following formula (4-1), and Y is a structural unit represented by the following formula (4-2), [ka] [In formulas (4-1) and (4-2), each Ar independently represents a structure having an unsubstituted or substituted aromatic ring, R 1 , R 2 are each independently a hydrogen atom, a methyl group, or an ethyl group, R' is a divalent hydrocarbon group having 2 to 12 carbon atoms; R 3 , R 4 , R 7 , R 8 each independently represents a hydroxyl group, a glycidyl ether group, or a 2-methylglycidyl ether group, R 5 , R 6 , R 9 , R 10 are each independently a hydrogen atom or a methyl group, n1 is an integer of 4 to 16, and n2 is the average number of repeating units and is 2 to 30. R 11 , R 12 are each independently a glycidyl ether group or a 2-methylglycidyl ether group, R 13 , R 14 each independently represents a hydroxyl group, a glycidyl ether group, or a 2-methylglycidyl ether group, R 15 , R 16 is a hydrogen atom or a methyl group, m1, m2, p1, p2, q are the mean values ​​of the repetitions, m1 and m2 each independently represent 0 to 25, and m1+m2≧1; p1 and p2 each independently represent a number from 0 to 5; q is between 0.5 and 5. However, the bond between the structural unit X represented by the formula (4-1) and the structural unit Y represented by the formula (4-2) may be random or block, and the total number of the structural units X and Y present in one molecule is m1 and m2, respectively.

[0036] The epoxy resin contained in the epoxy resin composition of the present invention may be an epoxy resin represented by the following formula (5): Use of such an epoxy resin improves the repairability and remoldability of the cured epoxy resin product, and provides a good balance between flexibility and toughness. [ka] (In formula (5), p1, p2, q, m 2 and n 2 is the average value of the repetitions, and each is independently p1 is 0 to 5, p2 is 0 to 5, q is 0.5 to 5, m 2 is 1 ~25, n 2 is 2 to 30.)

[0037] As the epoxy resin contained in the epoxy resin composition of the present invention, an epoxy resin (DGEBA) represented by the following formula (6) may be used. [ka] (In formula (6), n is the average value of the repetitions and is 0 to 100. Among these, n is preferably 0 to 1 as the average value of the repetitions in order to improve the fluidity of the composition.)

[0038] The epoxy resin composition of the present invention contains a DA curing agent as a curing agent for the epoxy resin, but may further contain another curing agent (a curing agent that can be used in combination.) The curing agent that can be used in combination is not particularly limited as long as it reacts with the epoxy resin to produce a cured product, and examples thereof include amine compounds, acid anhydride compounds, amide compounds, phenolic compounds, and carboxylic acid compounds.

[0039] Examples of the amine compounds include aliphatic polyamines such as ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, polypropylene glycol diamine, diethylenetriamine, triethylenetetramine, and pentaethylenehexamine; aromatic polyamines such as metaxylylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, and phenylenediamine; alicyclic polyamines such as 1,3-bis(aminomethyl)cyclohexane, isophoronediamine, and norbornanediamine; and dicyandiamide.

[0040] Examples of the acid anhydride compounds include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, maleic anhydride polypropylene glycol, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride.

[0041] Examples of the phenolic compounds include phenol novolac resins, cresol novolac resins, aromatic hydrocarbon formaldehyde resin-modified phenolic resins, dicyclopentadiene-phenol adduct resins, phenol aralkyl resins, naphthol aralkyl resins, trimethylolmethane resins, tetraphenylolethane resins, naphthol novolac resins, naphthol-phenol co-condensed novolac resins, naphthol-cresol co-condensed novolac resins, biphenyl-modified phenolic resins, aminotriazine-modified phenolic resins, and modified products thereof. Examples of latent catalysts include imidazole, BF3-amine complexes, and guanidine derivatives.

[0042] Examples of the amide compounds include aliphatic polyamides synthesized from polycarboxylic acids and polyamines, aromatic polyamides obtained by introducing an aromatic ring into the aliphatic polyamides, aliphatic polyamide adducts obtained by adding an epoxy compound to a polyamide, and aromatic polyamide adducts.

[0043] Examples of the carboxylic acid compound include carboxylic acid polymers such as carboxylic acid-terminated polyester, polyacrylic acid, and maleic acid-modified polypropylene glycol, and active ester resins.

[0044] The curing agents that can be used in combination may be used alone or in combination of two or more. For applications such as underfill materials and general coatings, it is preferable to use the amine compounds, carboxylic acid compounds, and / or acid anhydride compounds. For applications such as adhesives and flexible wiring boards, amine compounds, particularly dicyandiamide, are preferred in terms of workability, curability, and long-term stability. For applications as semiconductor encapsulation materials, solid phenolic compounds are preferred in terms of the heat resistance of the cured product.

[0045] The concentration of the DA curing agent in the epoxy resin composition of the present invention is controlled to 0.10 mmol / g or more based on the total mass of the epoxy resin and DA curing agent. This configuration ensures that the cured epoxy resin obtained by heat-treating the epoxy resin composition has good repairability and remoldability. On the other hand, if the concentration of the DA curing agent in the epoxy resin composition is less than 0.10 mmol / g, it may be difficult to obtain a cured epoxy resin having good repairability and remoldability. The concentration of the DA curing agent in the epoxy resin composition of the present invention is more preferably 0.10 to 3.00 mmol / g, and even more preferably 0.15 to 2.00 mmol / g. Furthermore, when the epoxy resin composition of the present invention contains the above-mentioned concomitant curing agent, the concentration of the DA curing agent in the epoxy resin composition of the present invention is preferably 0.10 mmol / g or more, more preferably 0.10 to 3.00 mmol / g, and even more preferably 0.15 to 2.00 mmol / g, based on the total mass of the epoxy resin, DA curing agent, and concomitant curing agent. The concentration of the DA curing agent of the present invention can be appropriately selected based on the glass transition temperature, defined as the tan δ peak top of a dynamic mechanical analyzer (DMA) measurement of a cured product obtained from the target epoxy resin composition. For example, when the glass transition temperature is used as a guideline, if the glass transition temperature of the cured product is near room temperature, sufficient repairability and remoldability are likely to be exhibited even at the lower concentration end of the preferred range. On the other hand, if the glass transition temperature of the target cured product is above 100°C, these functions are likely to be exhibited at the higher concentration end of the preferred range. However, in the temperature range above the glass transition temperature measured by DMA, molecular mobility is generally high, and sufficient repairability and reshapeability functions are likely to be exhibited even at low DA curing agent concentrations, so the effect of exhibiting repairability and reshapeability functions can be adjusted, for example, by appropriately adjusting the aging temperature for repair and the heating temperature for reshaping. Thus, the relationship between the glass transition temperature of the cured product and the concentration of the DA curing agent of the present invention is not limited to these.

[0046] The epoxy resin composition of the present invention may further contain a filler, a fibrous substrate, a dispersion medium, a resin other than the above-mentioned various compounds, etc. Each of the components will be described in detail below.

[0047] <Filler> The epoxy resin composition of the present invention may further contain a filler. Examples of the filler include inorganic fillers and organic fillers. Examples of the inorganic filler include inorganic fine particles.

[0048] Examples of inorganic fine particles with excellent heat resistance include alumina, magnesia, titania, zirconia, and silica (quartz, fumed silica, precipitated silica, silicic anhydride, fused silica, crystalline silica, and ultrafine amorphous silica). Examples of inorganic fine particles with excellent thermal conductivity include boron nitride, aluminum nitride, alumina oxide, titanium oxide, magnesium oxide, zinc oxide, silicon oxide, and diamond. Examples of inorganic fine particles with excellent electrical conductivity include metal fillers and / or metal-coated fillers using metals or alloys (e.g., iron, copper, magnesium, aluminum, gold, silver, platinum, zinc, manganese, and stainless steel). Examples of inorganic fine particles with excellent barrier properties include minerals such as mica, clay, kaolin, talc, zeolite, wollastonite, and smectite, as well as potassium titanate, magnesium sulfate, sepiolite, zonolite, aluminum borate, calcium carbonate, titanium oxide, barium sulfate, zinc oxide, and magnesium hydroxide. Examples of materials with a high refractive index include barium titanate, zirconia oxide, and titanium oxide. Examples of materials exhibiting photocatalytic properties include photocatalytic metals such as titanium, cerium, zinc, copper, aluminum, tin, indium, phosphorus, carbon, sulfur, thorium, nickel, iron, cobalt, silver, molybdenum, strontium, chromium, barium, and lead, as well as composites of these metals and oxides thereof. Examples of materials with excellent abrasion resistance include metals such as silica, alumina, zirconia, and magnesium oxide, as well as composites and oxides thereof. Examples of materials with excellent conductivity include metals such as silver and copper, tin oxide, and indium oxide. Examples of materials with excellent insulating properties include silica. Examples of materials with excellent UV blocking properties include titanium oxide and zinc oxide.

[0049] These inorganic fine particles may be selected appropriately depending on the application, and may be used alone or in combination of two or more kinds. In addition, the inorganic fine particles have various properties other than those exemplified, so they may be selected appropriately depending on the application.

[0050] For example, when silica is used as inorganic fine particles, known silica fine particles such as powdered silica or colloidal silica can be used without any particular limitation.As commercially available powdered silica fine particles, for example, Aerosil 50, 200 manufactured by Nippon Aerosil Co., Ltd., Sildex H31, H32, H51, H52, H121, H122 manufactured by Asahi Glass Co., Ltd., E220A, E220 manufactured by Nippon Silica Industrial Co., Ltd., SYLYSIA470 manufactured by Fuji Silysia Co., Ltd., SG Flake manufactured by Nippon Sheet Glass Co., Ltd., etc. can be mentioned.In addition, as commercially available colloidal silica, for example, methanol silica sol, IPA-ST, MEK-ST, NBA-ST, XBA-ST, DMAC-ST, ST-UP, ST-OUP, ST-20, ST-40, ST-C, ST-N, ST-O, ST-50, ST-OL manufactured by Nissan Chemical Industries, Ltd. can be mentioned.

[0051] Surface-modified silica fine particles may also be used, for example, the silica fine particles that have been surface-treated with a reactive silane coupling agent having a hydrophobic group, or modified with a compound having a (meth)acryloyl group. Examples of commercially available powdered silica modified with a compound having a (meth)acryloyl group include Aerosil RM50, R711, etc. manufactured by Nippon Aerosil Co., Ltd., and examples of commercially available colloidal silica modified with a compound having a (meth)acryloyl group include MIBK-SD, etc. manufactured by Nissan Chemical Industries, Ltd.

[0052] The shape of the silica fine particles is not particularly limited, and spherical, hollow, porous, rod-like, plate-like, fibrous, or amorphous shapes can be used. The primary particle diameter is preferably in the range of 5 to 200 nm. A diameter of 5 nm or more ensures sufficient dispersion of the inorganic fine particles in the dispersion, while a diameter of 200 nm or less facilitates maintaining sufficient strength of the cured product.

[0053] Titanium oxide microparticles can be used not only as extender pigments but also as ultraviolet light-responsive photocatalysts, such as anatase titanium oxide, rutile titanium oxide, and brookite titanium oxide. Furthermore, particles designed to respond to visible light by doping different elements into the crystalline structure of titanium oxide can also be used. Suitable elements for doping titanium oxide include anionic elements such as nitrogen, sulfur, carbon, fluorine, and phosphorus, and cationic elements such as chromium, iron, cobalt, and manganese. The titanium oxide can be used in the form of a powder, a sol dispersed in an organic solvent or water, or a slurry. Commercially available powdered titanium oxide microparticles include, for example, Aerosil P-25 manufactured by Nippon Aerosil Co., Ltd. and ATM-100 manufactured by Teika Co., Ltd. Commercially available slurry-type titanium oxide microparticles include, for example, TKD-701 manufactured by Teika Co., Ltd.

[0054] <Fiber matrix> The epoxy resin composition of the present invention may further contain a fibrous substrate. The fibrous substrate is not particularly limited, but is preferably one used in fiber-reinforced resins, such as inorganic fibers and organic fibers.

[0055] Examples of inorganic fibers include inorganic fibers such as carbon fiber, glass fiber, boron fiber, alumina fiber, and silicon carbide fiber, as well as carbon fiber, activated carbon fiber, graphite fiber, glass fiber, tungsten carbide fiber, silicon carbide fiber (silicon carbide fiber), ceramic fiber, alumina fiber, natural fiber, mineral fiber such as basalt, boron fiber, boron nitride fiber, boron carbide fiber, and metal fiber. Examples of the metal fiber include aluminum fiber, copper fiber, brass fiber, stainless steel fiber, and steel fiber.

[0056] Examples of organic fibers include synthetic fibers made from resin materials such as polybenzazole, aramid, PBO (polyparaphenylene benzoxazole), polyphenylene sulfide, polyester, acrylic, polyamide, polyolefin, polyvinyl alcohol, and polyarylate; natural fibers such as cellulose, pulp, cotton, wool, and silk; and regenerated fibers such as protein, polypeptide, and alginic acid.

[0057] Among these, carbon fiber and glass fiber are preferred because they have a wide range of industrial applications. Of these, only one type may be used, or two or more types may be used simultaneously.

[0058] The fibrous substrate may be an assembly of fibers, with continuous or discontinuous fibers, in the form of a woven or nonwoven fabric, in the form of a fiber bundle in which the fibers are aligned in one direction, or in the form of a sheet in which fiber bundles are arranged, or in the form of a three-dimensional shape in which a thickness is added to an assembly of fibers.

[0059] <Dispersion medium> The epoxy resin composition of the present invention may contain a dispersion medium for the purpose of adjusting the solid content mass and viscosity of the composition. The dispersion medium may be any liquid medium that does not impair the effects of the present invention, and examples of the dispersion medium include various organic solvents and liquid organic polymers.

[0060] Examples of the organic solvent include ketones such as acetone, methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK); cyclic ethers such as tetrahydrofuran (THF), and dioxolane; esters such as methyl acetate, ethyl acetate, and butyl acetate; aromatics such as toluene and xylene; and alcohols such as carbitol, cellosolve, methanol, isopropanol, butanol, and propylene glycol monomethyl ether. These can be used alone or in combination, but acetone and methyl ethyl ketone are preferred from the standpoint of solubility of constituent materials such as epoxy resins and curing agents, volatility during coating, and solvent recovery.

[0061] The liquid organic polymer is a liquid organic polymer that does not directly contribute to the curing reaction, and examples thereof include an acrylic polymer (Floren WK-20: Kyoeisha), an amine salt of a special modified phosphate ester (HIPLAAD ED-251: Kusumoto Chemicals), and a modified acrylic block copolymer (DISPERBYK2000: BYK-Chemie).

[0062] <Resin> The epoxy resin composition of the present invention may contain a resin other than the various compounds of the present invention described above. As the resin, any known and commonly used resin may be blended as long as it does not impair the effects of the present invention, and for example, a thermosetting resin or a thermoplastic resin may be used.

[0063] Thermosetting resins are resins that can become substantially insoluble and infusible when cured by heat, radiation, or a catalyst. Specific examples include urea resins, melamine resins, benzoguanamine resins, alkyd resins, unsaturated polyester resins, vinyl ester resins, diallyl terephthalate resins, silicone resins, urethane resins, furan resins, ketone resins, xylene resins, thermosetting polyimide resins, benzoxazine resins, aniline resins, cyanate ester resins, styrene-maleic anhydride (SMA) resins, and maleimide resins. These thermosetting resins can be used alone or in combination.

[0064] Thermoplastic resins refer to resins that can be melt-molded by heating. Specific examples include polyethylene resins, polypropylene resins, polystyrene resins, rubber-modified polystyrene resins, acrylonitrile-butadiene-styrene (ABS) resins, acrylonitrile-styrene (AS) resins, polymethyl methacrylate resins, acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polyethylene terephthalate resins, ethylene vinyl alcohol resins, cellulose acetate resins, ionomer resins, polyacrylonitrile resins, polyamide resins, polyacetal resins, polybutylene terephthalate resins, polylactic acid resins, polyphenylene ether resins, modified polyphenylene ether resins, polycarbonate resins, polysulfone resins, polyphenylene sulfide resins, polyetherimide resins, polyethersulfone resins, polyarylate resins, thermoplastic polyimide resins, polyamideimide resins, polyetheretherketone resins, polyketone resins, liquid crystal polyester resins, fluororesins, syndiotactic polystyrene resins, and cyclic polyolefin resins. These thermoplastic resins can be used alone or in combination of two or more.

[0065] (Method of producing epoxy resin composition) The epoxy resin composition of the present invention is prepared by dissolving the aforementioned DA curing agent and epoxy resin, and optionally the aforementioned compatible curing agent, filler, fibrous substrate, dispersing medium, and resins other than the aforementioned various compounds, in a dispersing medium such as the aforementioned organic solvent. After dissolution, the solvent is distilled off and the resulting mixture is dried under reduced pressure using a vacuum oven or the like to obtain an epoxy resin composition. The epoxy resin composition of the present invention may also be in a state in which the aforementioned constituent materials are homogeneously mixed. In this case, homogeneous mixing is preferably performed using a mixer or the like. The blending ratio of each constituent material can be appropriately adjusted depending on the desired properties of the cured epoxy resin, such as mechanical strength, heat resistance, repairability, and remoldability. In addition, in preparing the epoxy resin composition, the constituent materials can be mixed in the following order: first, an organic solvent such as acetone or methyl ethyl ketone is added to the epoxy resin and stirred; then, a DA curing agent is added as a curing agent; the mixture is stirred again to homogenize it; and the mixture is concentrated and dried under reduced pressure to obtain an epoxy resin composition in which the constituent materials are more homogeneously mixed.

[0066] (cured epoxy resin) The cured epoxy resin of the present invention is obtained by curing an epoxy resin with a DA curing agent having one Diels-Alder reaction unit in the molecule, which comprises an anthracene structure and a maleimide structure, and the Diels-Alder reaction unit has at least two phenolic hydroxyl groups. The epoxy resin may be any of the commonly known epoxy resins described above as the epoxy resin contained in the epoxy resin composition of the present invention.

[0067] Because the cured epoxy resin product of the present invention is cured with a DA curing agent with excellent thermal stability as described above, it is possible to suppress a decrease in crosslink density even in high-temperature environments and maintain good mechanical strength. Furthermore, it is believed that applying mechanical energy, such as scratching or external force, to the cured epoxy resin product of the present invention cleaves the C—C bond in the Diels-Alder reaction unit, producing anthracene and maleimide on the cleaved surface. However, since the equilibrium shifts toward the bond in the Diels-Alder reaction between anthracene and maleimide at temperatures below 200°C, it is believed that an adduct (Diels-Alder reaction unit) is again formed, allowing for repair of scratches and remolding.

[0068] The following formula (7) shows a schematic diagram of the Diels-Alder reaction (DA reaction: crosslinking reaction) and retro Diels-Alder reaction (rDA reaction: reversible crosslinking / decrosslinking reaction) for a cured epoxy resin obtained by curing an epoxy resin with a DA curing agent. Formula (7) specifically illustrates a cured epoxy resin obtained by curing an epoxy resin (DGEBA) represented by formula (6) with a curing agent represented by formula (2) as a DA curing agent. In the example of formula (7), when an epoxy resin composition containing a curing agent represented by formula (2) and an epoxy resin is heat-treated, the epoxy groups of the epoxy resin bond with the phenolic hydroxyl groups of the anthracene structure and maleimide structure in the Diels-Alder reaction unit of the curing agent represented by formula (2), forming a three-dimensional network structure. Furthermore, when mechanical energy, such as scratching or external force, is applied, the C-C bond in the Diels-Alder reaction unit is cleaved, separating the anthracene structure and maleimide structure, resulting in decrosslinking. Even if the crosslinking has been decomposed, heating at a certain temperature will cause the Diels-Alder reaction to occur again, restoring the three-dimensional network structure and making it possible to repair damage and reshape. It is also preferable to utilize phase separation and place the reversible bonds in the cured product in a low modulus phase to promote the reversible crosslinking / decompassing reactivity. [ka]

[0069] (Method of producing a cured epoxy resin product) Next, a method for producing a cured epoxy resin product of the present invention will be described in detail. The cured epoxy resin product of the present invention can be produced by heating the epoxy resin composition of the present invention and curing the epoxy resin contained in the epoxy resin composition with a DA curing agent. Specifically, the epoxy resin composition of the present invention is cast into a silicone casting slab or the like, and after degassing if necessary, is subjected to heat curing to harden the epoxy resin, thereby obtaining a cured epoxy resin product. The step of casting into a silicone casting slab or the like can be carried out, for example, by sandwiching the epoxy resin composition between mirror-finished aluminum plates or the like using silicone tubes as spacers.

[0070] Known curing accelerators can be used in the method for producing a cured epoxy resin material of the present invention. The curing accelerator is not particularly limited, but examples include urea compounds, phosphorus-based compounds, tertiary amines, imidazoles, organic acid metal salts, Lewis acids, amine complex salts, quaternary ammonium salts, tin carboxylates, and organic peroxides. When used as an adhesive, urea compounds, particularly 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), are preferred due to their excellent workability and low-temperature curing properties. When used as a semiconductor encapsulating material or as an electronic material such as a printed circuit board or build-up substrate, phosphorus-based compounds such as triphenylphosphine and tertiary amines such as dimethylaminopyridine, imidazoles, 1,8-diazabicyclo-[5.4.0]-undecene (DBU), and benzyldimethylamine are preferred due to their excellent curability, heat resistance, electrical properties, and moisture resistance reliability.

[0071] The structure of the obtained cured epoxy resin product can be confirmed by infrared absorption (IR) spectroscopy using Fourier transform infrared spectroscopy (FT-IR) or the like, elemental analysis, X-ray scattering, or the like.

[0072] (Uses of epoxy resin compositions and cured epoxy resin products) The epoxy resin composition of the present invention and a cured epoxy resin product prepared from the epoxy resin composition (hereinafter also referred to as the cured epoxy resin product of the present invention) are excellent in both heat resistance and repairability, and are also remoldable, and are useful for the following applications:

[0073] <Laminate> The cured epoxy resin product of the present invention can be laminated with a substrate to form a laminate. The substrate for the laminate can be inorganic materials such as metal and glass, or organic materials such as plastic and wood, as appropriate for the application. The substrate may be in the form of a laminate, such as a flat plate, a sheet, or a three-dimensional structure, or may be cubic. Any shape suitable for the purpose, such as one with cured surface entirely or partially, may be used. There are no limitations on the hardness or thickness of the substrate. Alternatively, a multilayer laminate may be formed by laminating a first substrate, a layer comprising the cured product of the epoxy resin composition of the present invention, and a second substrate in this order. Because the epoxy resin composition of the present embodiment has excellent adhesive properties, it can be suitably used as an adhesive for bonding a first substrate and a second substrate. Alternatively, the cured epoxy resin product of the present invention may be used as a substrate, and then laminated with the cured epoxy resin product of the present invention.

[0074] The epoxy resin composition of the present invention has particularly high adhesion to metals and / or metal oxides, making it particularly suitable for use as a primer for metals. Examples of metals include copper, aluminum, gold, silver, iron, platinum, chromium, nickel, tin, titanium, zinc, various alloys, and composite materials of these. Examples of metal oxides include single oxides and / or composite oxides of these metals. Because the epoxy resin composition has particularly excellent adhesion to iron, copper, and aluminum, it can be suitably used as an adhesive for iron, copper, and aluminum.

[0075] The cured epoxy resin product of the present invention is particularly suitable for use in bonding dissimilar materials because of its ability to relieve stress. For example, even in a laminate in which the substrate is a metal and / or metal oxide and the second substrate is a dissimilar material such as a plastic layer, the adhesive strength is maintained due to the stress relaxation ability of the cured epoxy resin product of the present invention.

[0076] In a laminate obtained by laminating a cured epoxy resin product of the present invention and a substrate, a layer containing the cured product may be formed by direct coating or molding on the substrate, or an already molded product may be laminated. When directly coating, the coating method is not particularly limited, and examples thereof include spraying, spin coating, dipping, roll coating, blade coating, doctor roll coating, doctor blade coating, curtain coating, slit coating, screen printing, and inkjet printing. When directly molding, examples thereof include in-mold molding, insert molding, vacuum molding, extrusion lamination molding, and press molding. When laminating a molded composition, an uncured or semi-cured composition layer may be laminated and then cured, or a layer containing a fully cured cured product of the composition may be laminated on the substrate. Alternatively, the cured epoxy resin product of the present invention may be laminated by coating a precursor capable of serving as a substrate and curing it, or the precursor capable of serving as a substrate or the epoxy resin composition of the present invention may be adhered in an uncured or semi-cured state and then cured. The precursor capable of serving as a substrate is not particularly limited, and examples thereof include various curable resin compositions.

[0077] <Adhesive> The cured epoxy resin product of the present invention can be suitably used as an adhesive for structural components in the fields of automobiles, trains, civil engineering and construction, electronics, aircraft, and the space industry. Even when used to bond dissimilar materials, such as metals and non-metals, the adhesive maintains high adhesion regardless of changes in temperature and is resistant to peeling. In addition to structural applications, the adhesive can also be used for general office and medical applications, carbon fiber, and storage battery cells, modules, and cases. It can also be used as an adhesive for bonding optical components, bonding optical disks, mounting printed wiring boards, die bonding adhesives, semiconductor adhesives such as underfills, BGA reinforcing underfills, anisotropic conductive films, anisotropic conductive pastes, and other mounting applications.

[0078] <Fiber reinforced resin> When the epoxy resin composition of the present invention has a fibrous substrate, and the fibrous substrate is a reinforcing fiber, the epoxy resin composition containing the fibrous substrate can be used as a fiber-reinforced resin. The method for incorporating the fibrous substrate into the composition is not particularly limited as long as the effects of the present invention are not impaired. Examples include methods for combining the fibrous substrate and the composition by methods such as kneading, coating, impregnation, injection, and pressure bonding, and the method can be selected appropriately depending on the form of the fiber and the application of the fiber-reinforced resin.

[0079] The method for molding fiber-reinforced resins is not particularly limited. To produce plate-shaped products, extrusion molding is commonly used, but flat presses are also possible. Other methods that can be used include extrusion molding, blow molding, compression molding, vacuum molding, and injection molding. To produce film-shaped products, melt extrusion and solution casting can be used. Examples of melt molding methods include inflation film molding, cast molding, extrusion lamination molding, calendar molding, sheet molding, fiber molding, blow molding, injection molding, rotational molding, and coating molding. For resins that are cured with active energy rays, cured products can be produced using various curing methods using active energy rays. In particular, when a thermosetting resin is used as the main component of the matrix resin, examples of molding methods include prepreg molding of the molding material and pressurizing and heating it using a press or autoclave. Other examples include RTM (Resin Transfer Molding), Vacuum-assisted Resin Transfer Molding (VaRTM), laminate molding, and hand layup molding.

[0080] <Other molding materials> The epoxy resin composition of the present invention provides cured epoxy resin products having good heat resistance and repairability, and also has remoldability, and can therefore be used as molding materials for large cases, motor housings, casting materials for the inside of cases, gears, pulleys, etc. These may be cured products of the resin alone, or cured products reinforced with fiber such as glass chips.

[0081] <Prepreg> Fiber-reinforced resins can be formed into an uncured or semi-cured state known as a prepreg. After distributing the product in the prepreg state, final curing may be performed to form a cured product. When forming a laminate, it is preferable to form the prepreg, then stack other layers, and then perform final curing, since this allows the formation of a laminate in which each layer is tightly adhered. The mass ratio of the composition and fibrous substrate used in this case is not particularly limited, but it is generally preferable to prepare the prepreg so that the resin content is 20 to 60 mass%.

[0082] <Heat-resistant materials and electronic materials> The epoxy resin composition of the present invention provides cured epoxy resin products that exhibit both excellent heat resistance and repairability, and are remoldable, making them suitable for use as heat-resistant and electronic materials. The composition is particularly suitable for semiconductor encapsulation, circuit boards, build-up films, build-up boards, adhesives, and resist materials. It is also suitable for use as a matrix resin for fiber-reinforced resins, and is particularly suitable as a highly heat-resistant prepreg. The heat-resistant and electronic components thus obtained are suitable for a variety of applications, including, but not limited to, industrial machine parts, general machine parts, automobile, railway, and vehicle parts, aerospace and aviation-related parts, electronic and electrical components, building materials, containers and packaging materials, household goods, sports and leisure goods, and housing components for wind power generation.

[0083] Below, we will explain some representative products by giving examples. 1.Semiconductor encapsulation materials A method for obtaining a semiconductor encapsulating material from the epoxy resin composition of the present invention includes thoroughly melt-mixing the composition, a curing accelerator, and compounding ingredients such as an inorganic filler, using an extruder, kneader, roll, or the like, as needed, until uniform. In this process, fused silica is typically used as the inorganic filler. However, for use as a high-thermal-conductivity semiconductor encapsulating material for power transistors and power ICs, highly filled inorganic fillers such as crystalline silica, alumina, and silicon nitride, which have higher thermal conductivity than fused silica, or fused silica, crystalline silica, alumina, and silicon nitride may be used. The inorganic filler is preferably used in an amount of 30 to 95% by mass per 100 parts by mass of the epoxy resin composition. In particular, a filler content of 70 parts by mass or more is more preferred, and 80 parts by mass or more is even more preferred, in order to improve flame retardancy, moisture resistance, and solder crack resistance and to reduce the linear expansion coefficient.

[0084] 2. Semiconductor Devices The semiconductor package molding method for obtaining a semiconductor device from the epoxy resin composition of the present invention includes molding the semiconductor encapsulating material using a casting machine, a transfer molding machine, an injection molding machine or the like, and then heating the molded product at 50 to 250°C for 2 to 10 hours.

[0085] 3. Printed wiring board A method for obtaining a printed wiring board from the epoxy resin composition of the present invention includes laminating the above prepreg by a conventional method, appropriately overlaying copper foil, and heat-pressing the laminate under a pressure of 1 to 10 MPa at 170 to 300°C for 10 minutes to 3 hours.

[0086] 4. Build-up board A method for obtaining a build-up substrate from the epoxy resin composition of the present invention includes, for example, the following steps. First, the composition, which contains an appropriate blend of rubber, filler, and the like, is applied to a circuit board on which a circuit has been formed using a spray coating method, curtain coating method, or the like, and then cured (Step 1). Subsequently, if necessary, predetermined through-holes or the like are drilled, the surface is treated with a roughening agent, and the surface is washed with hot water to form a roughened surface, followed by plating with a metal such as copper (Step 2). These operations are sequentially repeated as desired to alternately build up resin insulating layers and conductor layers of a predetermined circuit pattern (Step 3). Note that drilling of through-holes is performed after the formation of the outermost resin insulating layer. Alternatively, the build-up substrate of the present invention can be produced by forming a roughened surface by heat-pressing a copper foil, in which the resin composition has been semi-cured on a copper foil, onto a wiring board on which a circuit has been formed, at 170 to 300°C, thereby eliminating the steps of forming a roughened surface and plating.

[0087] 5. Build-up film A build-up film can be obtained from the epoxy resin composition of the present invention by applying the epoxy resin composition to the surface of a support film, which is a substrate, and then drying the organic solvent by heating or by blowing hot air onto the composition to form a layer of the epoxy resin composition.

[0088] The organic solvent used here is preferably, for example, a ketone such as acetone, methyl ethyl ketone, or cyclohexanone; an acetate ester such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, or carbitol acetate; a carbitol such as cellosolve or butyl carbitol; an aromatic hydrocarbon such as toluene or xylene; dimethylformamide, dimethylacetamide, or N-methylpyrrolidone; and it is preferably used in a proportion such that the nonvolatile content is 30 to 60% by mass.

[0089] The thickness of the formed epoxy resin composition layer is usually equal to or greater than the thickness of the conductor layer. Since the thickness of the conductor layer of a circuit board is usually in the range of 5 to 70 μm, the thickness of the resin composition layer is preferably 10 to 100 μm. The epoxy resin composition layer may be protected with a protective film, which will be described later. Protection with a protective film can prevent the adhesion of dust and the like to the surface of the resin composition layer and scratches.

[0090] Examples of the support film and protective film include polyolefins such as polyethylene, polypropylene, and polyvinyl chloride; polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as "PET") and polyethylene naphthalate; polycarbonate; polyimide; and even release paper and metal foils such as copper foil and aluminum foil. The support film and protective film may be subjected to a mud treatment, a corona treatment, or a release treatment. The thickness of the support film is not particularly limited, but is usually 10 to 150 μm, and preferably 25 to 50 μm. The thickness of the protective film is preferably 1 to 40 μm.

[0091] The support film is peeled off after laminating it onto a circuit board or after forming an insulating layer by heat curing. If the support film is peeled off after the curable resin composition layer constituting the build-up film is heat cured, adhesion of dust and the like during the curing process can be prevented. When peeling off after curing, the support film is usually subjected to a release treatment in advance.

[0092] A multilayer printed circuit board can be produced using the build-up film obtained as described above. For example, if the epoxy resin composition layer is protected by a protective film, the film is peeled off, and then the epoxy resin composition layer is laminated onto one or both sides of the circuit board so as to be in direct contact with the circuit board, for example, by a vacuum lamination method. The lamination method may be a batch method or a continuous method using a roll. If necessary, the build-up film and the circuit board may be heated (preheated) before lamination. The lamination conditions are preferably a pressure bonding temperature (lamination temperature) of 70 to 140°C and a pressure bonding pressure of 1 to 11 kgf / cm. 2 (9.8×10 4 ~107.9×10 4 N / m 2 ), and lamination is preferably carried out under reduced air pressure of 20 mmHg (26.7 hPa) or less.

[0093] 6.Conductive paste A conductive paste can be obtained from the epoxy resin composition of the present invention by dispersing conductive particles in the composition. Depending on the type of conductive particles used, the conductive paste can be a paste resin composition for circuit connection or an anisotropic conductive adhesive. [Example]

[0094] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0095] [Synthesis Example 1] -Synthesis of hydroxy compounds- A flask equipped with a thermometer and a stirrer was charged with 445 g (0.5 mol) of polytetramethylene glycol diglycidyl ether (Nagase ChemteX "Denacol EX-991L": epoxy equivalent 445 g / eq) and 228 g (1.0 mol) of bisphenol A (hydroxyl equivalent 114 g / eq). The mixture was heated to 140 °C over 30 minutes, and then 3.4 g of 4% aqueous sodium hydroxide solution was added. The mixture was then heated to 150 °C over 30 minutes and further reacted at 150 °C for 16 hours. A neutralizing amount of sodium phosphate was then added, yielding 673 g of a hydroxy compound represented by the following formula (8). Mass spectrometry of this hydroxy compound revealed a peak at M+ = 1380, which corresponds to the theoretical structure of formula (8) where m1 = 1 and n1 = 11. This confirmed that the hydroxy compound contained the target PTMG (polytetramethylene ether glycol) type (BPA: bisphenol A) hydroxy compound. The hydroxyl equivalent weight of this hydroxy compound calculated by GPC was 526 g / eq, the average value of n1 was 10.6, and the average value of m1 was 0.73.

[0096] [ka]

[0097] [Synthesis Example 2] -Synthesis of epoxy resin- In a flask equipped with a thermometer, a dropping funnel, a condenser, and a stirrer, 200 g of the hydroxy compound represented by formula (8) obtained by the synthesis above, 437 g (4.72 mol) of epichlorohydrin, and 118 g of n-butanol were added and dissolved while purging with nitrogen gas. After heating to 65°C, the pressure was reduced to an azeotropic pressure, and 6.66 g (0.08 mol) of a 49% aqueous sodium hydroxide solution was added dropwise over 5 hours. Stirring was then continued under the same conditions for 0.5 hours. During this time, the azeotropic distillate was separated using a Dean-Stark trap, the aqueous layer was removed, and the oil layer was returned to the reaction system while the reaction was continued. Unreacted epichlorohydrin was then removed by vacuum distillation. 150 g of methyl isobutyl ketone and 150 g of n-butanol were added to the resulting crude epoxy resin and dissolved. Further, 10 g of a 10% aqueous solution of sodium hydroxide was added to this solution, and the mixture was reacted at 80° C. for 2 hours, after which the mixture was washed three times with 50 g of water until the pH of the washing liquid became neutral. Next, the system was dehydrated by azeotropy, and after microfiltration, the solvent was distilled off under reduced pressure to obtain 190 g of the epoxy resin represented by the above formula (5). The epoxy equivalent of the obtained epoxy resin was 722 g / eq. The epoxy resin was found to have the following structure by mass spectrometry: m 2=1, n Since a peak of M+=1492 was obtained, which corresponds to the theoretical structure of p2=11, q=1, p1=0, and p2=0, it was confirmed that the product contained the epoxy resin represented by the above formula (5), which was the target product.

[0098] [Synthesis Example 3] -Synthesis of DA curing agent- A flask equipped with a thermometer, stirrer, and condenser was charged with 376 g (1 mol) of 9-(4-hydroxybenzyl)-10-(4-hydroxyphenyl)anthracene (manufactured by Asahi Organic Chemicals Co., Ltd.: product name BIP-ANT; hydroxyl equivalent 188 g / eq), 226 g (1.2 mol) of 4-hydroxyphenylmaleimide, 1880 g of toluene, and 1880 g of methyl isobutyl ketone, and the mixture was reacted at 80°C for 12 hours. The mixture was then cooled to room temperature, and the precipitate was collected by suction filtration and dried under reduced pressure to obtain a Diels-Alder adduct (DA curing agent represented by formula (3) above). The yield was 429 g, a 76% yield.

[0099] [Synthesis Example 4] -Synthesis of DA curing agent- A flask equipped with a thermometer, stirrer, and condenser was charged with 210 g (1 mol) of 2,6-dihydroxyanthracene, 226 g (1.2 mol) of 4-hydroxyphenylmaleimide, 1050 g of toluene, and 1050 g of methyl isobutyl ketone, and the mixture was reacted at 80°C for 12 hours. The mixture was then cooled to room temperature, and the precipitate was collected by suction filtration and dried under reduced pressure to obtain a Diels-Alder adduct (DA curing agent represented by formula (2) above). The yield was 379 g, a 95% yield.

[0100] [Synthesis Example 5] -Synthesis of hardener- A flask equipped with a thermometer, stirrer, and condenser was charged with 244 g (2 mol) of 2,6-xylenol and 129 g of 5.4% sodium hydroxide in methanol. After stirring and dissolving, the mixture was heated to reflux, and 96 g (1 mol) of furfural was added dropwise over 1 hour. The mixture was then allowed to react at reflux for 13 hours, neutralized with 140 g of 20% aqueous sodium dihydrogen phosphate, and 500 g of water was added. The precipitated crystals were then collected by suction filtration, washed with a 1:1 methanol:water solution, and dried under reduced pressure. 322 g (1 mol) of these crystals, 189 g (1 mol) of 4-hydroxyphenylmaleimide, and 1020 g of tetrahydrofuran were added and reacted at room temperature for 24 hours. The precipitate was then collected by suction filtration and dried under reduced pressure to obtain a Diels-Alder adduct (a curing agent represented by the following formula (9)). The yield was 369 g, a 72% yield.

[0101] [ka]

[0102] <Examples 1 to 3, Comparative Examples 1 and 2> -Preparation and evaluation of cured epoxy resin- Epoxy resin compositions were obtained by uniformly mixing the epoxy resin, curing agent, and curing accelerator according to the formulation shown in Table 1 using a mixer (Thinky Corporation's "Awatori Rentaro ARV-200") Table 1 shows the concentration of each curing agent in the obtained epoxy resin compositions. The epoxy resin in Table 1 refers to the epoxy resin represented by the above formula (5) or EPICLON 850S (a bisphenol-type liquid epoxy resin manufactured by DIC Corporation, epoxy equivalent weight 188 g / eq). The curing agents in Table 1 are the curing agent represented by the above formula (3), the curing agent represented by the above formula (2), the curing agent represented by the above formula (9), DICY (dicyandiamide, DICY7 manufactured by Mitsubishi Chemical Corporation), or XLC-LL (phenol aralkyl resin manufactured by Mitsui Chemicals, Inc., hydroxyl group equivalent: 176 g / eq). The curing accelerator in Table 1 is TPP (triphenylphosphine (reagent) manufactured by Tokyo Chemical Industry Co., Ltd.) or DCMU (3-(3,4-dichlorophenyl)-1,1-dimethylurea, B-605-IM manufactured by DIC Corporation). Next, the obtained epoxy resin composition was sandwiched between mirror-finished aluminum plates (JIS H 4000 A1050P, manufactured by Engineering Test Services Co., Ltd.) using a silicone tube as a spacer, and heat-cured under specified heating conditions to obtain a 0.7 mm-thick cured epoxy resin product. In Examples 1 and 3 and Comparative Example 1, a brown, transparent cured product was obtained, while in Example 2, a cloudy, phase-separated cured product was obtained. In Comparative Example 2, which used the curing agent represented by formula (9), foaming occurred during heat-curing, and no cured epoxy resin product was obtained.

[0103] The heating conditions (heating temperature and heating time) for the heat curing carried out in the above-mentioned Examples 1 to 3 and Comparative Examples 1 and 2 are shown below. Examples 1 and 3, Comparative Examples 1 and 2: 0.5 hours at 100°C + 1.5 hours at 130°C + 2 hours at 160°C + 2 hours at 180°C Example 2: 170°C for 0.5 hours

[0104] -Self-repairing test- The cured epoxy resin materials prepared in Examples 1 to 3 and Comparative Example 1 were cut with a razor, and the resulting fracture surfaces were brought into contact with each other and aged in a dryer at 190°C for 24 hours. After removal from the dryer, the cross sections of the cured epoxy resin materials were visually inspected for adhesion. Those that were bonded were rated "A," and those that were not bonded were rated "B." The evaluation results are shown in Table 1.

[0105] [Table 1]

[0106] According to Table 1, the epoxy resin cured products of Examples 1 to 3 all had a concentration of the curing agent in the epoxy resin composition of 0.10 mmol / g or more, and had good self-repairing properties. In contrast, the epoxy resin cured product according to Comparative Example 1 had poor self-repairing properties because the concentration of the curing agent in the epoxy resin composition was less than 0.10 mmol / g. Furthermore, all of the epoxy resin cured products according to Examples 1 to 3 were heat-cured at temperatures of 170° C. or higher, but did not decrosslink as in Comparative Example 2 and had good heat resistance.

[0107] <Examples 1 and 2, Comparative Example 1> -Remolding test- 0.1 g of the cured epoxy resin products prepared in Examples 1 and 2 and Comparative Example 1 were each cut into small pieces with scissors. A 1.08 mm thick Teflon (registered trademark) plate with a 5 mm x 40 mm window was placed on an aluminum plate, and the cut pieces of cured material were placed inside. An aluminum plate and a 1 kg weight were then placed on top of that, and the mixture was heated continuously at 150°C for 24 hours. The shape of the resulting cured product was observed visually. The evaluation results were as follows. The evaluation results of the cured epoxy resin products prepared in Examples 1 and 2 and Comparative Example 1 are shown below in Examples 4, 5, and Comparative Example 3, respectively. Examples 4 and 5: The seams disappeared and the cured product was integrated. Comparative Example 3: The pieces of the cured product stuck together, but came apart when lightly touched.

Claims

1. a curing agent having one Diels-Alder reaction unit consisting of an anthracene structure and a maleimide structure in the molecule, the Diels-Alder reaction unit having at least two phenolic hydroxyl groups; Epoxy resin, wherein the concentration of the curing agent relative to the total mass of the epoxy resin and the curing agent is 0.10 mmol / g or more; The epoxy resin composition according to claim 1, wherein the curing agent is represented by the following formula (1), and has an anthracene structure having at least one phenolic hydroxyl group and a maleimide structure having at least one phenolic hydroxyl group: 【Chemical 1】 (In formula (1), R 1 to R 11 each independently represent a hydrogen atom, a halogen atom, a hydroxy group, an alkoxy group, an aralkyloxy group, an aryloxy group, a nitro group, an amino group, an amido group, a carboxy group, an alkyloxycarbonyl group, an aryloxycarbonyl group, a cyano group, an alkyl group, a cycloalkyl group, an aralkyl group, or an aryl group, and at least one of R 1 to R 11 is a functional group containing a phenolic hydroxyl group or a group having a phenolic hydroxyl group as a substituent.)

2. 2. The epoxy resin composition according to claim 1, wherein the curing agent is represented by the following formula (2): 【Chemistry 2】

3. 2. The epoxy resin composition according to claim 1, wherein the curing agent is represented by the following formula (3): 【Chemistry 3】

4. 4. The epoxy resin composition according to claim 1, wherein the epoxy resin is represented by the following formula (4) and has an epoxy equivalent of 500 to 10,000 g / eq: 【Chemistry 4】 In formula (4), each Ar independently represents a structure having an unsubstituted or substituted aromatic ring, X is a structural unit represented by the following formula (4-1), and Y is a structural unit represented by the following formula (4-2): 【Chemistry 5】 [In formulas (4-1) and (4-2), each Ar independently represents a structure having an unsubstituted or substituted aromatic ring, R 1 , R 2 are each independently a hydrogen atom, a methyl group, or an ethyl group, R' is a divalent hydrocarbon group having 2 to 12 carbon atoms; R 3 , R 4 , R 7 , R 8 each independently represents a hydroxyl group, a glycidyl ether group, or a 2-methylglycidyl ether group, R 5 , R 6 , R 9 , R 10 are each independently a hydrogen atom or a methyl group, n 1 is an integer from 4 to 16, and n 2 is the average number of repeating units and is 2 to 30.] R 11 , R 12 are each independently a glycidyl ether group or a 2-methylglycidyl ether group, R 13 , R 14 each independently represents a hydroxyl group, a glycidyl ether group, or a 2-methylglycidyl ether group, R 15 , R 16 is a hydrogen atom or a methyl group, m 1 , m 2 , p 1 , p 2 , q is the average value of the iterations, m 1 , m 2 are each independently 0 to 25, and m 1 +m 2 ≧1, p 1 , p 2 are each independently 0 to 5, q is 0.5 to 5. However, the bond between the structural unit X represented by the formula (4-1) and the structural unit Y represented by the formula (4-2) may be random or block, and the total number of the structural units X and Y present in one molecule is m 1 , m 2 Indicates that

5. The epoxy resin composition according to claim 4, wherein the epoxy resin is represented by the following formula (5): 【Chemistry 6】 (In formula (5), p 1 , p 2 , q, m 2 and n 2 are the average values ​​of the repeats, and each independently represents p 1 is 0 to 5, p 2 is 0 to 5, q is 0.5 to 5, m2 is 1 to 25, and n2 is 2 to 30.

6. A cured epoxy resin product obtained by curing the epoxy resin composition according to any one of claims 1 to 5.

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