Epoxy resin, curable composition, cured product, and electrical / electronic component

Abstract

Provided are: a phenolic novolac type epoxy resin with which it is possible to obtain a cured product having a low molecular weight, excellent handleability, excellent low dielectric characteristics, and water absorbency; and a curable composition containing said phenolic novolac type epoxy resin and a curing agent. A phenolic novolac type epoxy resin according to one embodiment of the present invention is represented by a specific formula, wherein the proportion of a binuclear body is 50.0-99.9 area% according to gel permeation chromatography measurement, and the proportion of 2,4' isomer in the binuclear body is 16.0-99.9 area% according to high-performance liquid chromatography measurement.

Description

Epoxy resins, curable compositions, cured products, and electrical and electronic parts

[0001] The present invention relates to an epoxy resin, a curable composition, a cured product, and an electric / electronic part. This application claims priority to Japanese Patent Application No. 2023-211581, filed December 14, 2023, the contents of which are incorporated herein by reference.

[0002] Epoxy resins, typified by diglycidyl ethers, have excellent adhesive properties, water resistance, mechanical strength, and electrical properties, and are therefore used in a variety of fields, such as adhesives, paints, civil engineering and construction materials, and insulating materials for electrical and electronic components. In particular, in the electrical and electronic field, they are widely used in insulating casting, laminate materials, sealing materials, etc. In recent years, multilayer circuit boards used in electrical and electronic devices have become smaller, lighter, and more highly functional, and there is a demand for them to be further multilayered, higher density, thinner, lighter, and with improved reliability and moldability.

[0003] Low dielectric properties are an important requirement for epoxy resins used in electrical and electronic components, such as laminates for electrical and electronic circuits. In recent years, communication frequencies have become increasingly higher to improve the volume and speed of information transmission, and the increase in transmission loss (α) has become a major issue. The lower the α value, the less attenuation of the information signal and the higher the reliability of communication. Because α is proportional to frequency (f), communication in the high-frequency range increases α, leading to reduced reliability. One method for suppressing α is to reduce the dielectric loss tangent (tan δ), which, like f, is proportional to α. For high-speed transmission of communication signals, materials with low tan δ, i.e., low dielectric properties, are required.

[0004] Furthermore, high reliability is required for electrical and electronic components such as laminates for electrical and electronic circuits, and the epoxy resins used as materials must have a balance of various properties, including low dielectric properties, compatibility, and low water absorption.

[0005] Low-molecular-weight bisphenol A epoxy resins (bisphenol A diglycidyl ethers) are widely known as epoxy resins used in electrical and electronic components, such as laminates for electrical and electronic circuits. However, their dielectric properties are insufficient. Furthermore, medium- to high-molecular-weight phenol novolac epoxy resins are widely known, but these also lack sufficient dielectric properties. Meanwhile, low-molecular-weight phenol novolac epoxy resins have also been investigated. Patent Document 1 discloses a phenol novolac epoxy resin with a structure primarily consisting of a dinuclear unit. However, unsubstituted phenol novolac epoxy resins exhibit poor water absorption. In recent years, diglycidyl ethers with various skeletons have been investigated. Patent Document 2 discloses bisphenol AF diglycidyl ether, which has superior dielectric properties to bisphenol A glycidyl ether. However, its dielectric properties remain insufficient.

[0006] Japanese Patent Publication No. 2017-071706 Japanese Patent Publication No. 2013-155337

[0007] In recent years, laminates for electrical and electronic circuits have become increasingly complex and smaller in size. As thinner laminates are required to improve dimensional stability, and as the amount of information in telecommunications and communication speeds increase, the resin compositions of these laminates need to be more complex in order to reduce energy loss in communication signals. This has led to an increase in the importance of low-molecular-weight epoxy resins, which have good solubility in solvents, compatibility with other resins, and dispersibility of fine particle fillers such as silica, as well as ease of handling.

[0008] Bisphenol A diglycidyl ether is known as a common low-molecular-weight type, but its dielectric properties are insufficient. Furthermore, phenolic novolac epoxy resins are generally of medium to high molecular weight, but their high resin viscosity makes them difficult to disperse fine particle fillers such as silica, and their dielectric properties are also insufficient. Furthermore, unsubstituted phenolic novolac epoxy resins have poor water absorption properties.

[0009] The present invention aims to provide a phenolic novolac epoxy resin that has a low molecular weight, is easy to handle, and can give a cured product with excellent low dielectric properties and water absorption. The present invention also aims to provide a curable composition containing the phenolic novolac epoxy resin and a curing agent, a cured product thereof, and an electric / electronic part.

[0010] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by including a specific ratio of dinuclear compounds among phenol novolac epoxy resins, and further including a specific ratio of 2,4' isomers in the dinuclear compounds.

[0011] That is, the gist of the present invention lies in the following [1] to

[10] .

[0012] [1] An epoxy resin represented by the following formula (1), wherein the proportion of dinuclear isomers is 50.0 to 99.9 area % as measured by gel permeation chromatography, and the proportion of 2,4' isomers in the dinuclear isomers is 16.0 to 99.9 area % as measured by high performance liquid chromatography:

[0013]

[0014] (In formula (1), R １are each independently an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, or an alkynyl group having 2 to 12 carbon atoms. Each n is independently 1 to 3, and m represents the number of repetitions and is an integer of 0 or greater.) [2] The epoxy resin of [1], having an epoxy equivalent of 170 to 500 g / equivalent. [3] The epoxy resin of [1] or [2], having a melt viscosity at 100°C of 8.0 Pa s or less. [4] The epoxy resin of any of [1] to [3], having a total chlorine content of 5,000 ppm by mass or less. [5] A curable composition comprising the epoxy resin of any of [1] to [4] and a curing agent. [6] The curable composition of [5], comprising 0.01 to 500 parts by mass of the curing agent per 100 parts by mass of the epoxy resin. [7] The curable composition of [5] or [6], wherein the curing agent is at least one selected from the group consisting of phenolic curing agents, amide curing agents, imidazole curing agents, and active ester curing agents. [8] A cured product of the curable composition of any one of [5] to [7]. [9] An electric or electronic part comprising the curable composition of any one of [5] to [7].

[10] An electric or electronic part comprising the cured product of [8].

[0015] The present invention provides an epoxy resin with a low molecular weight, excellent handleability, and capable of yielding a cured product with excellent low dielectric properties and water absorption. The epoxy resin provided by the present invention has excellent handleability due to its low molecular weight and low resin viscosity. For example, in the manufacturing process of multilayer printed wiring board materials, improved industrial handleability and improved content and dispersibility of particulate fillers such as silica are expected. Furthermore, the epoxy resin provided by the present invention can yield a cured product with excellent low dielectric properties and water absorption. Therefore, the epoxy resin provided by the present invention and a curable composition containing the epoxy resin provided by the present invention are applicable to a variety of fields, such as adhesives, paints, civil engineering and building materials, and insulating materials for electric and electronic components. They are particularly useful as insulating casting materials, laminate materials, and encapsulating materials in the electric and electronic fields. For example, they can be suitably used in multilayer printed wiring boards, laminates for electric and electronic circuits such as capacitors, adhesives such as film adhesives and liquid adhesives, semiconductor encapsulating materials, underfill materials, interchip fills for 3D-LSIs, insulating sheets, prepregs, heat dissipation substrates, and the like.

[0016] An embodiment of the present invention will be described in detail below. However, the description of the constituent elements described below is merely an example of an embodiment of the present invention, and the present invention is not limited to the following description as long as it does not deviate from the gist of the present invention. In this specification, the expression "to" is used to include the numerical values ​​or physical property values ​​before and after the expression. The epoxy resin of one embodiment of the present invention (hereinafter also referred to as the "epoxy resin of this embodiment") may be one having a repeating structure or one having a monomolecular structure, and in the art, both epoxy compounds may be referred to and sold as "epoxy resin" or "epoxy resin composition." In addition, in the art, a mixture containing an epoxy resin other than the epoxy resin of this embodiment may be referred to as an "epoxy resin composition," or may simply be referred to as "epoxy resin."

[0017] [Epoxy Resin] The epoxy resin of this embodiment is a phenol novolac epoxy resin represented by the following formula (1), in which the proportion of dinuclear units in the entire epoxy resin is 50.0 to 99.9 area % as measured by gel permeation chromatography, and the proportion of 2,4' isomers in the dinuclear units is 16.0 to 99.9 area % as measured by high performance liquid chromatography.

[0018]

[0019] In formula (1), R １ are each independently an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, or an alkynyl group having 2 to 12 carbon atoms. Each n is independently an integer of 1 to 3, and m represents the number of repetitions and is an integer of 0 or more.

[0020] The dinuclear compound is a compound in which m in formula (1) is 0. The 2,4' isomer of the dinuclear compound means a structure in which, with respect to the bonding sites with the methylene groups linking the two aromatic nuclei, one aromatic nucleus is bonded to a methylene group at the 2-position (ortho-position) relative to the glycidyloxy group, and the other aromatic nucleus is bonded to a methylene group at the 4-position (para-position) relative to the glycidyloxy group.

[0021] R １ are each independently an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, or an alkynyl group having 2 to 12 carbon atoms, and the alkyl group, alkoxy group, aryl group, cycloalkyl group, alkenyl group, and alkynyl group may have a substituent.

[0022] Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an n-hexyl group, an isohexyl group, an n-heptyl group, a methylcyclohexyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, a benzyl group, a methylbenzyl group, a dimethylbenzyl group, a trimethylbenzyl group, a naphthylmethyl group, a phenethyl group, and a 2-phenylisopropyl group.

[0023] Examples of the alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group, an n-pentoxy group, an isopentoxy group, a neopentoxy group, a tert-pentoxy group, a cyclopentoxy group, an n-hexyloxy group, an isohexyloxy group, a cyclohexyloxy group, an n-heptoxy group, a cycloheptoxy group, a methylcyclohexyloxy group, an n-octoxy group, and the like. Examples of the alkyl group include a thyloxy group, a cyclooctyloxy group, an n-nonyloxy group, a 3,3,5-trimethylcyclohexyloxy group, an n-decyloxy group, a cyclodecyloxy group, an n-undecyloxy group, an n-dodecyloxy group, a cyclododecyloxy group, a benzyloxy group, a methylbenzyloxy group, a dimethylbenzyloxy group, a trimethylbenzyloxy group, a naphthylmethoxy group, a phenethyloxy group, and a 2-phenylisopropoxy group.

[0024] Examples of the aryl group include a phenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, an ethylphenyl group, a styryl group, a xylyl group, an n-propylphenyl group, an isopropylphenyl group, a mesityl group, an ethynylphenyl group, a naphthyl group, and a vinylnaphthyl group.

[0025] Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, a cyclodecyl group, a cyclododecyl group, and a methylcyclohexyl group.

[0026] Examples of the alkenyl group include a vinyl group, a 1-propenyl group, a 2-propenyl group, a 1-methylvinyl group, a 1-butenyl group, a 2-butenyl group, a 3-butenyl group, a 1,3-butadienyl group, a cyclohexenyl group, a cyclohexadienyl group, a cinnamyl group, and a naphthylvinyl group.

[0027] Examples of the alkynyl group include an ethynyl group, a 1-propynyl group, a 2-propynyl group, a 1-butynyl group, a 2-butynyl group, a 3-butynyl group, a 1,3-butadienyl group, a phenylethynyl group, and a naphthylethynyl group.

[0028] R １ is preferably an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a cycloalkyl group having 6 to 12 carbon atoms, more preferably an alkyl group having 1 to 12 carbon atoms, and particularly preferably an alkyl group having 1 to 6 carbon atoms.

[0029] The substituent that the alkyl group, alkoxy group, aryl group, cycloalkyl group, alkenyl group, or alkynyl group may have is not particularly limited, and examples thereof include a halogen group, a cyano group, an amino group, a carboxyl group, an ester group, an alkylcarbonyl group, an acetyl group, a sulfonyl group, a silyl group, a boryl group, a nitrile group, a thio group, or a seleno group.

[0030] In formula (1), n's each independently represent an integer of 1 to 3, preferably 1 or 2, and more preferably 1.

[0031] In formula (1), m is an integer of 0 or more, preferably an integer of 0 to 5, more preferably an integer of 0 to 3, and most preferably 0 or 1.

[0032] Specific examples of the epoxy compound represented by formula (1) include R １ When is a methyl group, the compound represented by the following formula (A) can be mentioned. Furthermore, the included isomers can be mentioned as compounds represented by the following formulas (A-1) to (A-3).

[0033]

[0034]

[0035] [Content of Dinuclear Compounds in Epoxy Resin] The epoxy resin of this embodiment has a dinuclear compound content of 50.0 to 99.9 area %, preferably 60.0 to 99.9 area %, and more preferably 70.0 to 99.9 area %, as measured by gel permeation chromatography (GPC). If the area % is equal to or greater than the lower limit of the above range, the resulting epoxy resin tends to have an appropriate viscosity from the viewpoint of ease of handling. In the case of a high molecular weight compound, for example, when m in formula (1) above is 1 or greater, the number of epoxy groups per molecule increases. Therefore, a low content of high molecular weight compounds can suppress deterioration of the dielectric properties of the cured product during curing, so a high content of dinuclear compounds is preferred.

[0036] The binuclear content in the epoxy resin of this embodiment can be adjusted by adjusting the binuclear content of the phenol novolak raw material, or by employing an epoxidation method that suppresses polymerization.

[0037] In the epoxy resin of this embodiment, when phenolic novolak is epoxidized, there is a risk of producing a high molecular weight compound represented by the following formula (2). If there is a large amount of high molecular weight compound, the viscosity increases, making it difficult to handle, and further, secondary hydroxyl groups are generated, which deteriorates the dielectric properties of the cured product. In order to keep the binuclear component of the epoxy resin within the above range, it is preferable to suppress polymerization by the epoxy resin production method described below.

[0038]

[0039] In formula (2), R １ are each independently an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, or an alkynyl group having 2 to 12 carbon atoms. Each n is independently 1 to 3, and o represents the number of repetitions and is an integer of 1 or more. R in formula (2) １ , n are more specifically defined as R in the above formula (1), １ , n may be any number from 1 to 10.

[0040] [Content of 2,4' isomer in binuclear unit in epoxy resin] The epoxy resin of this embodiment has a content of 2,4' isomer in binuclear unit of 16.0 to 99.9 area %, preferably 20.0 to 98.2 area %, and more preferably 35.0 to 95.2 area %, as measured by high performance liquid chromatography. If the area % is equal to or greater than the lower limit of the above range, voids are generated in the three-dimensional structure of the cured product due to the asymmetry of the structure, resulting in good dielectric properties of the cured product. If the area % is equal to or less than the upper limit, this is preferred in terms of the time and cost required for purification.

[0041] The method for incorporating the 2,4' isomer into an epoxy resin is not particularly limited, but examples include a method of epoxidizing a phenolic novolac containing the 2,4' isomer, or a method of mixing a phenolic novolac epoxy resin containing the 2,4' isomer in a predetermined ratio with an epoxy resin. Furthermore, the 2,4' isomer ratio can be increased or decreased by subjecting a phenolic novolac or phenolic novolac epoxy resin containing the 2,4' isomer to chemical procedures such as column chromatography, distillation, and recrystallization. Because performing chemical procedures such as column chromatography, distillation, and recrystallization more than once reduces economic efficiency, it is preferable to perform them only once.

[0042] [Epoxy Equivalent] From the viewpoint of maintaining good dielectric properties and ease of handling, the epoxy equivalent of the epoxy resin of the present embodiment is preferably in the range of 170 to 500 g / equivalent. From the viewpoint of maintaining even better dielectric properties and ease of handling, the epoxy equivalent is preferably 170 to 450 g / equivalent, more preferably 170 to 400 g / equivalent, and even more preferably 170 to 350 g / equivalent.

[0043] [Viscosity] From the viewpoints of maintaining good handleability, compatibility with various inorganic and organic fillers and polymer components, and ease of dissolution in solvents, the epoxy resin of this embodiment preferably has a shear viscosity (melt viscosity) at 100°C of 8.0 Pa·s or less, more preferably 5 Pa·s or less, even more preferably 1 Pa·s or less, and particularly preferably 0.5 Pa·s or less. There is no particularly preferred range for the lower limit of the shear viscosity, and it may be 0 Pa·s or more, greater than 0 Pa·s, or 0.001 Pa·s or more. The above upper and lower limits can be arbitrarily combined. For example, it may be 0 to 8.0 Pa·s, 0 to 5 Pa·s, greater than 0 Pa·s but less than 1 Pa·s, or 0.001 to 0.5 Pa·s. The shear viscosity can be measured, for example, using a viscoelasticity measuring device.

[0044] [Total Chlorine Content] From the viewpoint of improving reliability when used in electric and electronic parts, particularly insulating materials, the total chlorine content of the epoxy resin of the present embodiment is preferably 5,000 ppm by mass or less, more preferably 3,000 ppm by mass or less, even more preferably 2,000 ppm by mass or less, and particularly preferably 1,500 ppm by mass or less. The total chlorine content can be measured in accordance with JIS K 7243-3.

[0045] [Method for Producing Epoxy Resin] The method for producing the epoxy resin of this embodiment described above is not particularly limited, but examples include a method in which epihalohydrin is mixed with 1 mole of hydroxyl groups of a phenolic novolak compound represented by the following formula (3) in a ratio of typically 1.00 to 20.0 moles, preferably 1.50 to 15.0 moles, more preferably 2.0 to 12.0 moles, and even more preferably 4.0 to 10.0 moles, per mole of hydroxyl groups, and the mixture is allowed to react. When the amount of epihalohydrin used is equal to or greater than the lower limit mentioned above, it is easy to suppress the formation of high molecular weight compounds, and viscosity increase is unlikely to occur, and deterioration of the dielectric properties and heat resistance of the cured product can be suppressed. When the amount of epihalohydrin used is equal to or less than the upper limit mentioned above, it is possible to suppress deterioration in economic efficiency.

[0046]

[0047] In formula (3), R １are each independently an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, or an alkynyl group having 2 to 12 carbon atoms. n is an integer of 1 to 3, and m represents the number of repetitions and is an integer of 0 or more. R in formula (3) １ , n, and m are defined as R in the above formula (1). １ , n, m conditions may be applied.

[0048] More specifically, a phenol novolak compound represented by formula (3) is mixed with an epihalohydrin such as epichlorohydrin and reacted in the presence of an alkali. The alkali is preferably an alkali metal hydroxide, either solid or in aqueous solution. This reaction can be carried out under atmospheric pressure or reduced pressure. The reaction temperature is typically 20 to 150°C when reacting under atmospheric pressure and typically 30 to 80°C when reacting under reduced pressure. The reaction is optionally carried out while maintaining a predetermined temperature, by azeotroping the reaction solution, cooling the volatilized vapor, separating the resulting condensate into oil and water, and returning the dehydrated oil to the reaction system. The alkali metal hydroxide is preferably added to the reaction system intermittently or continuously in small amounts over a period of 0.1 to 10 hours to prevent a rapid reaction. The total reaction time is typically 1 to 15 hours.

[0049] After completion of the reaction, the insoluble by-product salt is removed by filtration or by washing with water from the reaction solution containing the epoxy resin as the target product, and then the unreacted epihalohydrin is removed by distillation under reduced pressure, thereby obtaining the target epoxy resin.

[0050] In this reaction, epichlorohydrin or epibromohydrin is preferably used as the epihalohydrin, and sodium hydroxide or potassium hydroxide is preferably used as the alkali metal hydroxide.

[0051] In this reaction, a catalyst such as a quaternary ammonium salt such as tetramethylammonium chloride or tetraethylammonium bromide; a tertiary amine such as benzyldimethylamine or 2,4,6-tris(dimethylaminomethyl)phenol; an imidazole such as 2-ethyl-4-methylimidazole or 2-phenylimidazole; a phosphonium salt such as ethyltriphenylphosphonium iodide; or a phosphine such as triphenylphosphine may be used.

[0052] In this reaction, an inert organic solvent may be used, such as alcohols such as ethanol, isopropyl alcohol, and ethylene glycol; ketones such as acetone and methyl ethyl ketone; ethers such as dioxane; glycol ethers such as methoxypropanol; and aprotic polar solvents such as dimethyl sulfoxide and dimethylformamide.

[0053] The amount of saponifiable halogen in the resulting epoxy resin can be sufficiently reduced by reprocessing to obtain a purified epoxy resin with a sufficiently reduced amount of saponifiable halogen. In this case, the crude epoxy resin obtained by the reaction is redissolved in an inert organic solvent such as isopropyl alcohol, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, dioxane, methoxypropanol, or dimethyl sulfoxide, and an alkali metal hydroxide is added as a solid or in aqueous solution to carry out a ring-closure reaction at a temperature of about 20 to 120°C for 0.5 to 8 hours. After that, excess alkali metal hydroxide and by-product salts are removed by water washing or other methods, and the organic solvent is further removed by distillation under reduced pressure to obtain a purified epoxy resin.

[0054] When producing the epoxy resin of this embodiment, at least a phenolic novolak compound represented by formula (3) is used as a raw material. However, polyhydric hydroxy compounds other than the phenolic novolak compound represented by formula (3) (sometimes referred to herein as "other polyhydric hydroxy compounds") may also be used in combination to produce a mixture of the epoxy resin of this embodiment and the other epoxy resin. However, from the viewpoint of enhancing the effects of the present invention, the proportion of the phenolic novolak compound represented by formula (3) is preferably 72 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and particularly preferably 95 mol% or more, based on the total amount of all polyhydric hydroxy compounds used as raw materials. The upper limit is 100 mol%, and most preferably 100 mol%. In this specification, "polyhydric hydroxy compound" is a general term for dihydric or higher phenolic compounds and dihydric or higher alcohols.

[0055] Other polyhydric hydroxy compounds include various polyhydric phenols such as bisphenol A, bisphenol AF, bisphenol F, bisphenol S, bisphenol AD, hydroquinone, resorcinol, methylresorcinol, biphenol, tetramethylbiphenol, dihydroxynaphthalene, dihydroxydiphenyl ether, thiodiphenols, phenol novolac resin, cresol novolac resin, phenol aralkyl resin, biphenyl aralkyl resin, naphthol aralkyl resin, terpene phenol resin, dicyclopentadiene phenol resin, bisphenol A novolac resin, naphthol novolac resin, brominated bisphenol A, and brominated phenol novolac resin, as well as various phenols and benzaldehyde, hydroxybenzaldehyde, crotonaldehyde, and glycerol. Examples of the resin include polyhydric phenol resins obtained by a condensation reaction with various aldehydes such as lyoxal, polyhydric phenol resins obtained by a condensation reaction between a xylene resin and a phenol, various phenol resins such as co-condensation resins of heavy oils or pitches with phenols and formaldehydes, chain aliphatic diols such as ethylene glycol, trimethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, and 1,6-hexanediol, cyclic aliphatic diols such as cyclohexanediol and cyclodecanediol, and polyalkylene ether glycols such as polyethylene ether glycol, polyoxytrimethylene ether glycol, and polypropylene ether glycol.Among these, preferred are phenol novolak resins, phenol aralkyl resins, polyhydric phenol resins obtained by a condensation reaction of phenol with hydroxybenzaldehyde, biphenyl aralkyl resins, naphthol aralkyl resins, chain aliphatic diols such as ethylene glycol, trimethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, and 1,6-hexanediol, cyclic aliphatic diols such as cyclohexanediol and cyclodecanediol, and polyalkylene ether glycols such as polyethylene ether glycol, polyoxytrimethylene ether glycol, and polypropylene ether glycol.

[0056] Examples of methods for controlling the amount of binuclear compounds in the epoxy resin of this embodiment include a method for adjusting the molar ratio of the phenol novolak compound represented by formula (3) and epihalohydrin, which are raw materials in the reaction step described above, or the amount of alkali used, or a method for controlling the amount by treatment such as purification or distillation, or a combination of these methods.

[0057] Specifically, the content of binuclear compounds can be increased by increasing the amount of epihalohydrin used in the reaction. Furthermore, the content of high molecular weight compounds can be increased by using less than 1 mole of epihalohydrin per mole of phenolic hydroxyl groups in the starting phenol novolak compound represented by formula (3).

[0058] In addition, the content of dinuclear compounds can be increased by using an alkali amount lower than the reaction equivalent in the synthesis. Furthermore, there is also a method in which the content of dinuclear compounds is increased while the content of high molecular weight compounds is decreased by reacting the raw material phenol novolak compound represented by formula (3) with epihalohydrin to obtain a product, and then performing a distillation operation or a column chromatography operation. The opposite control is also possible depending on the conditions of the distillation operation or the column chromatography operation.

[0059] [Curable Composition] Another aspect of the present invention is a curable composition, which contains the epoxy resin of the present embodiment and a curing agent. The curable composition of the present embodiment can be appropriately blended with various additives, such as epoxy resins other than the epoxy resin of the present embodiment, inorganic fillers, coupling agents, antioxidants, etc., as needed. The incorporation of the epoxy resin of the present embodiment improves the handleability of the curable composition of the present embodiment, thereby improving compatibility with other components, increasing the amount of filler added, and improving the impregnation of glass cloth. Furthermore, the curable composition has excellent low dielectric properties, which is advantageous for achieving finer wiring, multilayering, higher density, and higher frequency in electrical and electronic components.

[0060] The content of the epoxy resin of this embodiment in the curable composition is not particularly limited, but from the viewpoint of low dielectric properties, it is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more. From the viewpoint of curing failure and heat resistance, it is preferably 99% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less. The above upper and lower limits can be arbitrarily combined. For example, it may be 1 to 99% by mass, 5 to 90% by mass, or 10 to 80% by mass.

[0061] [Curing Agent] A curing agent is a substance that contributes to a crosslinking reaction and / or a chain extension reaction between epoxy groups of an epoxy resin. In this specification, even a substance called a "curing accelerator" is considered to be a curing agent as long as it contributes to a crosslinking reaction and / or a chain extension reaction between epoxy groups of an epoxy resin.

[0062] In this specification, "solid content" means components excluding solvents, and includes not only solid epoxy resins but also semi-solid and viscous liquids. "Total epoxy resin components" means the sum of the epoxy resin of this embodiment and other epoxy resins described below.

[0063] The content of the curing agent in the curable composition is not particularly limited, but from the viewpoint of heat resistance and low dielectric properties, it is preferably 0.01 to 500 parts by mass, more preferably 0.01 to 250 parts by mass, even more preferably 0.01 to 200 parts by mass, and particularly preferably 0.01 to 150 parts by mass, relative to 100 parts by mass of the epoxy resin of the present embodiment.

[0064] The curing agent used in the curable composition of this embodiment is not particularly limited, and any curing agent generally known as an epoxy resin curing agent can be used. From the viewpoint of improving heat resistance, at least one selected from the group consisting of phenol-based curing agents, amide-based curing agents, imidazoles, active ester-based curing agents, etc. is preferred. Only one type of curing agent may be used, or two or more types may be mixed in any combination and ratio.

[0065] <Phenol-Based Curing Agent> As the curing agent used in the curable composition of this embodiment, a phenol-based curing agent is preferably used from the viewpoint of improving the handleability of the resulting curable composition and the heat resistance after curing.

[0066] Specific examples of phenolic curing agents include bisphenol A, bisphenol F, 4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenyl ether, 1,4-bis(4-hydroxyphenoxy)benzene, 1,3-bis(4-hydroxyphenoxy)benzene, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl ketone, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxybiphenyl, 2,2'-dihydroxybiphenyl, 10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide, phenol novolac, bisphenol A novolac, o-cresol novolac, m-cresol novolac, p-cresol novolac, xylenol novolac, poly-p-hydroxystyrene, hydroquinone, resorcinol, catechol, t-butylcatechol, t-butylhydroquinone, fluoroglycinol, pyrogallol, t-butylpyrogallol, allylated pyrogallol, polyallylated pyrogallol, 1,2,4-benzenetriol, 2,3,4-trihydroxybenzophenone, 1,2-dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, Examples include 1,8-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,4-dihydroxynaphthalene, 2,5-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 2,8-dihydroxynaphthalene, allylated products or polyallylated products of the above dihydroxynaphthalenes, allylated bisphenol A, allylated bisphenol F, allylated phenol novolak, and allylated pyrogallol.

[0067] The phenolic curing agents listed above may be used alone or in any combination and ratio of two or more.

[0068] When a phenolic curing agent is used as the curing agent, it is preferable to use it so that the equivalent ratio of the functional groups in the curing agent to the epoxy groups in all epoxy resin components in the curable composition is in the range of 0.8 to 1.5, since within this range, unreacted epoxy groups and functional groups of the curing agent are less likely to remain.

[0069] <Amide-Based Curing Agent> As the curing agent used in the curable composition of this embodiment, it is preferable to use an amide-based curing agent from the viewpoint of improving the heat resistance of the resulting curable composition.

[0070] Examples of the amide curing agent include dicyandiamide or a derivative thereof, a polyamide resin, etc. The amide curing agent may be used alone or in any combination and ratio of two or more kinds.

[0071] <Imidazoles (imidazole-based curing agents)> As the curing agent used in the curable composition of this embodiment, it is preferable to use imidazoles (imidazole-based curing agents) from the viewpoint of sufficiently progressing the curing reaction and improving heat resistance.

[0072] Examples of imidazoles include 2-phenylimidazole, 2-ethyl-4(5)-methylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyano-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1' ))]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, or adducts of these imidazoles added to epoxy resins. Because imidazoles have catalytic activity, they can generally be classified as curing accelerators, which will be described later, but in this specification they are classified as curing agents.

[0073] The imidazoles listed above may be used alone or in any combination and ratio of two or more. The imidazoles are preferably used in an amount of 0.1 to 20 mass% based on the total amount of all epoxy resin components and imidazoles as solids in the curable composition.

[0074] <Active Ester-Based Curing Agent> As the curing agent used in the curable composition of this embodiment, it is preferable to use an active ester-based curing agent from the viewpoint of ensuring low water absorption and low dielectric properties of the resulting cured product.

[0075] The active ester curing agent is not particularly limited, but generally, compounds having two or more highly reactive ester groups in one molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, or esters of heterocyclic hydroxy compounds, are preferably used.

[0076] The active ester curing agent is preferably one obtained by a condensation reaction between a carboxylic acid compound and / or a thiocarboxylic acid compound and a hydroxy compound and / or a thiol compound. In particular, from the viewpoint of improving heat resistance, an active ester resin obtained from a carboxylic acid compound or a halide thereof and a hydroxy compound is preferred, and an active ester resin obtained from a carboxylic acid compound or a halide thereof and a phenol compound and / or a naphthol compound is more preferred.

[0077] Examples of carboxylic acid compounds or halides thereof include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, pyromellitic acid, etc., and halides of these carboxylic acids. Examples of phenol compounds or naphthol compounds include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthaline, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, and dicyclopentadiene-phenol adduct resins.

[0078] Specific examples of preferred active ester resins include active ester resins containing a dicyclopentadiene-phenol addition structure, active ester resins containing a naphthalene structure, active ester resins which are acetylated phenol novolac, and active ester resins which are benzoylated phenol novolac. Of these, active ester resins containing a dicyclopentadiene-phenol addition structure and active ester resins containing a naphthalene structure are more preferred in terms of their excellent ability to improve peel strength.

[0079] More specifically, the active ester resin containing a dicyclopentadiene-phenol adduct structure includes compounds represented by the following formula (I) or (II).

[0080]

[0081] In formula (I), each B' is independently any structural moiety selected from the group consisting of the following structural formulae (B'-1) to (B'-6), and R ２１ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group, or an aralkyl group; Z is a phenyl group, a naphthyl group, or a phenyl group or naphthyl group having 1 to 3 alkyl groups having 1 to 4 carbon atoms on the aromatic nucleus; l is 0 or 1; and k' is an average of 0.05 to 3.5 for the repeating units.

[0082]

[0083] In formulas (B'-1) to (B'-6), R ２２ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group, or an aralkyl group; R ２３ are each independently an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a phenyl group; Y is a linear alkylene group having 2 to 6 carbon atoms, an ether bond, a carbonyl group, a carbonyloxy group, a sulfide group, or a sulfone group; o represents the number of repetitions and is an integer of 1 to 4; and p is an integer of 1 to 4.

[0084]

[0085] In formula (II), W is a phenyl group or a naphthyl group, l' is 0 or 1, and k" is an average of 0.05 to 3.5 for the repeating units. In formula (II), from the viewpoint of reducing the dielectric tangent of the cured product of the resin composition and improving the heat resistance, W is preferably a naphthyl group, l' is preferably 0, and k" is preferably 0.25 to 1.5. Furthermore, polyarylates can also be used as curing agents similar to the active ester resins represented by formulas (I) and (II).

[0086] Commercially available active ester curing agents include HPC-8000-65T (an active ester curing agent containing a dicyclopentadiene structure) and HPC-8150-60T (an active ester curing agent containing a naphthalene structure in the main skeleton) (each manufactured by DIC Corporation), and W-575 and V-575 (polyarylates having a bisphenol skeleton, each manufactured by Unitika Ltd.).

[0087] The active ester curing agent may be used alone or in any combination and ratio of two or more. The active ester curing agent is preferably used so that the equivalent ratio of the active ester groups in the curing agent to the epoxy groups in all epoxy resins in the curable composition is in the range of 0.2 to 2.0.

[0088] <Other Curing Agents> Examples of other curing agents that can be used in the curable composition of the present embodiment include amine-based curing agents (excluding tertiary amines), acid anhydride-based curing agents, tertiary amines, organic phosphines, phosphonium salts, tetraphenylboron salts, organic acid dihydrazides, boron halide amine complexes, polymercaptan-based curing agents, isocyanate-based curing agents, blocked isocyanate-based curing agents, carbodiimides, etc. The other curing agents may be used alone, or two or more may be mixed in any combination and ratio.

[0089] [Other Epoxy Resins] The curable composition of the present embodiment may contain other epoxy resins. By using other epoxy resins, it is possible to compensate for insufficient physical properties or improve various physical properties.

[0090] The other epoxy resins are preferably those having two or more epoxy groups in the molecule, and various epoxy resins can be used, such as bisphenol A type epoxy resins, bisphenol AF type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol Z type epoxy resins, naphthalene type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, phenol aralkyl type epoxy resins, biphenyl type epoxy resins, triphenylmethane type epoxy resins, dicyclopentadiene type epoxy resins, etc. These can be used alone or as a mixture of two or more types.

[0091] When the curable composition of this embodiment uses the epoxy resin of this embodiment and another epoxy resin, the amount of the other epoxy resin, based on 100% by mass of the total epoxy resin components as solids, is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, and is preferably 99% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less. The above upper and lower limits can be arbitrarily combined. For example, it may be 1 to 99% by mass, 5 to 95% by mass, or 10 to 90% by mass. By having the proportion of the other epoxy resin at or above the above lower limit, the physical property improving effect of blending the other epoxy resin can be fully obtained. By having the proportion of the other epoxy resin at or below the above upper limit, the effects of the epoxy resin of this embodiment can be fully exhibited, which is preferable from the viewpoint of obtaining physical property improving effects such as high heat resistance and low dielectric resistance.

[0092] [Solvent] The curable composition of this embodiment may be diluted with a solvent to appropriately adjust the viscosity of the curable composition when handling it to form a coating film. In the curable composition of this embodiment, the solvent is used to ensure the handleability and workability of the curable composition when molding it, and there is no particular limit to the amount used. In this specification, the term "solvent" and the aforementioned term "solvent" are used to distinguish between them depending on their usage form, but they may be the same or different independently.

[0093] Examples of solvents that may be contained in the curable composition of this embodiment include ketones such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, and cyclohexanone; esters such as ethyl acetate; ethers such as ethylene glycol monomethyl ether; amides such as N,N-dimethylformamide and N,N-dimethylacetamide; alcohols such as methanol and ethanol; alkanes such as hexane and cyclohexane; and aromatics such as toluene and xylene. The solvents may be used alone, or two or more may be mixed in any combination and ratio.

[0094] [Other Components] The curable composition of the present embodiment may contain components other than those listed above (sometimes referred to as "other components" in this specification) for the purpose of further improving its functionality. Examples of such other components include thermosetting resins and photocurable resins other than epoxy resins, curing accelerators (excluding those included in the "curing agent"), ultraviolet inhibitors, antioxidants, coupling agents, plasticizers, fluxes, flame retardants, colorants, dispersants, emulsifiers, elasticity reducing agents, diluents, antifoaming agents, ion trapping agents, inorganic fillers, and organic fillers.

[0095] [Cured Product] One embodiment of the present invention is a cured product obtained by curing the curable composition according to one embodiment of the present invention. The cured product according to this embodiment, obtained by curing the epoxy resin according to this embodiment with a curing agent, provides a curable composition with excellent handleability, allowing for increased filler addition amounts and improved glass cloth impregnation. Furthermore, the cured product has excellent heat resistance and low dielectric properties, making it advantageous for fine wiring, multilayering, high density, and high frequency in electronic components. "Curing" here refers to intentionally curing the curable composition with heat and / or light, etc., and the degree of curing can be controlled depending on the desired physical properties and application. The degree of progress of the curing reaction may be fully cured or semi-cured, and is not particularly limited, but the reaction rate of the curing reaction between the epoxy groups and the curing agent is typically 5 to 95%.

[0096] The curing method of the curable composition according to one embodiment of the present invention to produce a cured product of this embodiment varies depending on the components and their amounts in the curable composition, but examples of the method include heating at 80 to 280°C for 60 to 360 minutes. This heating may be performed in two stages: a primary heating at 80 to 160°C for 10 to 90 minutes, and a secondary heating at 120 to 200°C for 60 to 150 minutes. In addition, in formulations in which the glass transition temperature (Tg) exceeds the secondary heating temperature, a tertiary heating at 150 to 280°C for 60 to 120 minutes may be performed. Performing secondary and tertiary heating in this manner is preferable from the viewpoint of reducing poor curing and residual solvent.

[0097] When producing a semi-cured resin product, it is preferable to allow the curing reaction of the curable composition to proceed to an extent that the shape can be maintained by heating, etc. When the curable composition contains a solvent, most of the solvent is usually removed by techniques such as heating, reduced pressure, air drying, etc., but 5% by mass or less of the solvent may remain in the semi-cured resin product.

[0098] [Applications] The epoxy resin of this embodiment has excellent productivity and handleability, as well as excellent heat resistance and low dielectric properties. It also improves the handleability of its curable composition, and can increase the amount of filler added, improve compatibility with other resin components, and improve impregnation into glass cloth. Therefore, it is applicable to various fields, such as adhesives, paints, civil engineering and construction materials, and insulating materials for electrical and electronic components. It is particularly useful as insulating casting, laminating materials, sealing materials, etc. in the electrical and electronic fields.

[0099] Examples of applications of the epoxy resin of this embodiment, the curable composition containing it, or the cured product thereof include, but are not limited to, electric and electronic components such as multilayer printed wiring boards and laminates for electric and electronic circuits such as capacitors, adhesives such as film adhesives and liquid adhesives, semiconductor encapsulation materials, underfill materials, interchip fills for 3D-LSIs, insulating sheets, prepregs, and heat dissipation substrates.

[0100] One embodiment of the present invention is an electrical or electronic component, which is made using a curable composition or a cured product thereof according to one embodiment of the present invention, for example, a component comprising a curable composition or a cured product thereof. In this specification, the term "electrical or electronic circuit laminate" refers to a laminate comprising a layer containing a curable composition according to one embodiment of the present invention or a layer consisting of a cured product of the curable composition and a conductive metal layer. The term "electrical or electronic circuit laminate" also refers to a laminate comprising a layer containing a curable composition or a layer consisting of a cured product of the curable composition and a conductive metal layer, and is used as a concept that includes, for example, a capacitor, even if it is not an electric or electronic circuit. The laminate for electrical or electronic circuits may contain two or more layers of curable compositions, as long as at least one layer contains the curable composition according to one embodiment of the present invention. Two or more conductive metal layers may also be formed.

[0101] In the laminate for electric / electronic circuits, the thickness of the layer made of the curable composition or the cured product thereof, which is one embodiment of the present invention, is usually about 10 to 200 μm, and the thickness of the conductive metal layer is usually about 0.2 to 70 μm.

[0102] [Conductive Metal] Examples of the conductive metal in the laminate for electrical and electronic circuits include metals such as copper and aluminum, and alloys containing these metals. In the present embodiment, the conductive metal layer of the laminate for electrical and electronic circuits can be a metal foil of these metals, or a metal layer formed by plating or sputtering.

[0103] [Method for Manufacturing Laminated Boards for Electrical and Electronic Circuits] Examples of methods for manufacturing laminated boards for electrical and electronic circuits in this embodiment include the following. (1) A nonwoven fabric or cloth made of inorganic and / or organic fiber materials such as glass fiber, polyester fiber, aramid fiber, cellulose, or nanofiber cellulose is impregnated with the curable composition of one embodiment of the present invention (hereinafter also simply referred to as the "curable composition") to form a prepreg. A conductive metal layer is then formed by conductive metal foil and / or plating, and a circuit is then formed using a photoresist or the like. The required number of such layers are then stacked to form a laminate. (2) The prepreg described in (1) above is used as a core material, and a layer of the curable composition and a conductive metal layer are laminated on one or both sides of the core material, and the curable composition is cured (build-up method). The layer of the curable composition may contain organic and / or inorganic fillers. (3) A laminated board for electrical and electronic circuits is formed by alternately stacking only layers of the curable composition and conductive metal layers without using a core material.

[0104] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Note that the values ​​of various production conditions and evaluation results in the following examples represent preferred upper or lower limit values ​​in the embodiments of the present invention, and a preferred range may be defined by a combination of the above-mentioned upper or lower limit values ​​and the values ​​in the following examples or values ​​between the examples.

[0105] [Raw materials used, etc.] The structural formulae of the raw materials, reaction products, etc. used in the following examples and comparative examples are as follows.

[0106] Ortho-cresol novolak represented by the following formula (4) (Asahi Organic Chemicals Co., Ltd., product name "BIOC-F", hereinafter referred to as "compound (4)")

[0107]

[0108] Purified ortho-cresol novolak represented by the following formula (5) (Asahi Organic Chemicals Co., Ltd., product name "PP-BIOC-F", hereinafter referred to as "compound (5)")

[0109]

[0110] Bisphenol AF (Central Glass Co., Ltd., trade name: Bis-AF(H), hereinafter referred to as “compound (6)”)

[0111]

[0112] A commercially available ortho-cresol novolac epoxy resin represented by the following formula (7) (hereinafter referred to as "compound (7)")

[0113]

[0114] (p is an average of 6 to 8 repeating units.)

[0115] Bisphenol F epoxy resin (product name: jER1750 (manufactured by Mitsubishi Chemical)

[0116] Bisphenol A epoxy resin (trade name: jER828US (manufactured by Mitsubishi Chemical)) Bisphenol AF epoxy resin (hereinafter abbreviated as compound (8))

[0117]

[0118] [Methods for Evaluating Physical Properties and Characteristics] [Measurement and Evaluation Methods] The physical properties of the ortho-cresol novolac epoxy resins and their cured products obtained in the following Examples and Comparative Examples were measured and evaluated as follows.

[0119] <Analysis of Dinuclear Content> A gel permeation chromatography measurement device, "HLC-8320 GPC Device" manufactured by Tosoh Corporation, was used. Separation was performed using "TSKGEL Super HM-H + H5000 + H4000 + H3000 + H2000" manufactured by Tosoh Corporation, and the content ratio of dinuclear compounds was determined from the analysis chart. Eluent: tetrahydrofuran Flow rate: 0.5 ml / min Detection: UV Temperature: 40°C Sample concentration: 0.1 to 0.2% by mass Injection amount: 10 μl

[0120] <Analysis of the content of 2,4' isomer contained in dinuclear complex> As a high-performance liquid chromatography measurement device, "Pump: PU-4185-Binary", "PDA detector: MD-41010", "Column heater: CO-4060", "Autosampler: AS-4150", "Interface box: LC-NetII / ADC", "Valve unit: RV-2080-02" manufactured by JASCO Corporation were used, and separation was performed using "Unifinepak C18 3.0 mmΦ x 150 mm 3 μm" manufactured by JASCO Corporation, and the area % of the 2,4' isomer contained in the dinuclear complex was calculated. Eluent: Gradient analysis of acetonitrile / water = 30 / 70 to 100 / 0 in 60 minutes Flow rate: 0.5 ml / min Detection: UV Temperature: 40 ° C. Sample concentration: 0.1 to 0.2 mass% Injection amount: 10 μl

[0121] <Epoxy Equivalent Weight> Measured in accordance with JIS K 7236 and expressed as a value converted into solid content.

[0122] <Shear Viscosity> Using a cone and plate viscometer CV-1D manufactured by Toa Kogyo Co., Ltd., a sample was dropped onto a plate, and then the viscosity was measured at 100° C. using a parallel plate (10P) at a rotation speed of 750 rpm.

[0123] <Total Chlorine Content> The total chlorine content was measured in accordance with JIS K 7243-3.

[0124] <Dielectric Properties> A film of the cured epoxy resin produced by the method described below was cut into test pieces measuring 2 mm in width and 80 mm in length. The obtained test pieces were measured for their dielectric properties (dielectric constant: Dk, dielectric loss tangent: Df) at measurement frequencies (1 GHz and 10 GHz) using a network analyzer by the cavity resonance perturbation method. Details of the equipment used and the measurement environment are described below. Note that the dielectric properties were calculated using dedicated measurement software provided by the cavity resonator manufacturer. Equipment used: Network analyzer E8361A manufactured by Agilent Technologies; Cavity resonators CP215 (1 GHz), CP184 (10 GHz) manufactured by Kanto Electronics Application Development Co., Ltd.; Measurement environment: Temperature 23°C, relative humidity 50% RH

[0125] <Water Absorption> A film of a cured epoxy resin produced by the method described below was cut into test pieces 40 mm wide and 40 mm long, and tested under conditions of 85°C and 85% RH. Measurement environment: temperature 85°C, relative humidity 85% RH Calculation method: Water absorption = (weight after test (g) - weight before test (g)) / weight before test (g) x 100

[0126] <Glass transition temperature (Tg)> The glass transition temperature of an epoxy resin produced by the method described below was measured by raising the temperature from 30 to 250°C at a rate of 10°C / min using a DSC7020 manufactured by SII Nano Technology Co., Ltd. The glass transition temperature here was measured based on the "midpoint glass transition temperature: Tmg" described in JIS K7121 "Method for measuring transition temperature of plastics."

[0127] [Raw Materials, etc.] The raw materials used in the following examples and comparative examples and their synthesis methods are as follows.

[0128] Example 1 Production of orthocresol novolac epoxy resin 100 g of orthocresol novolac (compound (4)) having a 2,4' isomer ratio of 50.8%, 527 g of epichlorohydrin, 206 g of isopropyl alcohol, and 73 g of pure water were charged into a 1 L flask and stirred at 40°C. Next, 84 g of 48.5% by mass sodium hydroxide solution was added dropwise over 1.5 hours at a temperature of 40 to 65°C, and the mixture was further maintained at 65°C for 30 minutes. The reaction mixture was heated to 145°C, and low-boiling components were distilled off under reduced pressure. Next, 182 g of methyl isobutyl ketone was added, and the mixture was heated to 65°C. 3 g of 48.5% by mass sodium hydroxide solution was added, and the mixture was stirred for 1 hour. The reaction mixture was washed four times with pure water, and the solvent was distilled off under reduced pressure at 100 to 150°C to obtain 140 g of an ortho-cresol novolac epoxy resin that was liquid at room temperature. Various measurements were carried out using the methods described above. The results are shown in Table 1.

[0129] [Example 2] 3.2 g of the ortho-cresol novolac epoxy resin synthesized in Example 1 and 6.8 g of the ortho-cresol novolac epoxy resin synthesized in Comparative Example 1 described below were mixed. Various measurements were carried out using the methods described above. The results are shown in Table 1.

[0130] [Example 3] 7.0 g of the ortho-cresol novolac epoxy resin synthesized in Example 1 and 3.0 g of the ortho-cresol novolac epoxy resin synthesized in Comparative Example 1 described below were mixed. Various measurements were carried out using the methods described above. The results are shown in Table 1.

[0131] Example 4 8.0 g of the ortho-cresol novolac epoxy resin synthesized in Example 1 was mixed with 2.0 g of the ortho-cresol novolac epoxy resin synthesized in Comparative Example 1 described below. Various measurements were carried out using the methods described above. The results are shown in Table 1.

[0132] Example 5 The procedure of Example 1 was repeated, except that the ortho-cresol novolac (compound (4)) having a 2,4' isomer ratio of 50.8% was replaced with an ortho-cresol novolac (compound (4)) having a 2,4' isomer ratio of 43.3%, to obtain 138 g of an ortho-cresol novolac epoxy resin that was liquid at room temperature. Various measurements were carried out using the methods described above. The results are shown in Table 1.

[0133] Example 6 The procedure of Example 1 was repeated, except that the ortho-cresol novolac (compound (4)) having a 2,4' isomer ratio of 50.8% was replaced with an ortho-cresol novolac (compound (4)) having a 2,4' isomer ratio of 54.0%, to obtain 142 g of an ortho-cresol novolac epoxy resin that was liquid at room temperature. Various measurements were carried out using the methods described above. The results are shown in Table 1.

[0134] [Example 7] The ortho-cresol novolac epoxy resin obtained in Example 1 was dissolved in hexane / ethyl acetate (3:1) to saturation, and the 2,4' isomer was isolated by silica gel column chromatography using hexane / ethyl acetate (3:1) as the developing solvent. Various measurements were carried out using the methods described above. The results are shown in Table 1.

[0135] [Example 8] The ortho-cresol novolac epoxy resin obtained in Example 7 was purified again using a column in the same manner as in Example 7 to isolate the 2,4' isomer. Various measurements were carried out using the methods described above. The results are shown in Table 1.

[0136] Comparative Example 1 The same procedure as in Example 1 was carried out, except that the type of ortho-cresol novolac was changed from compound (4) to compound (5), to obtain 140 g of an ortho-cresol novolac epoxy resin that was solid at room temperature. Various measurements were carried out using the methods described above. The results are shown in Table 2.

[0137] Comparative Example 2 0.2 g of the ortho-cresol novolac epoxy resin synthesized in Example 1 and 9.8 g of the ortho-cresol novolac epoxy resin synthesized in Comparative Example 1 were mixed. Various measurements were carried out using the methods described above. The results are shown in Table 2.

[0138] Comparative Example 3 A commercially available ortho-cresol novolac epoxy resin was subjected to various measurements using the methods described above. The results are shown in Table 2.

[0139] Comparative Example 4 Various measurements were carried out on the bisphenol F epoxy resin using the methods described above. The results are shown in Table 2.

[0140] Comparative Example 5 The bisphenol A epoxy resin was subjected to various measurements using the methods described above. The results are shown in Table 2.

[0141] Comparative Example 6 The same procedure as in Example 1 was carried out, except that compound (4) was changed to compound (6), to obtain 128 g of a bisphenol AF-type epoxy resin (compound (8)) that was solid at room temperature. Various measurements were carried out using the methods described above. The results are shown in Table 2.

[0142]

[0143]

[0144] As can be seen from the present examples and comparative examples, the epoxy resin of this embodiment, which is a phenol novolac epoxy resin and has a binuclear content of 50.0 to 99.9 area % as measured by gel permeation chromatography, has a low molecular weight and a low resin viscosity, and therefore is easy to handle.

[0145] In obtaining a curable composition from an epoxy resin, the following curing agent (B), other epoxy resin (D), and curing accelerator (E) were used.

[0146] [Curing Agent (B)] (B-1): Commercially available polyarylate resin (polyarylate having a bisphenol skeleton, active equivalent: 220 g / equivalent)

[0147] [Other Epoxy Resins (D)] (D-1): Other epoxy resins that can be used as film-forming agents, such as a polymeric epoxy resin (manufactured by Mitsubishi Chemical Corporation, trade name "YX7891T30", Mn: 10,000, Mw: 30,000, epoxy equivalent: 6,000 g / equivalent, resin content: 30% by mass).

[0148] [Curing Accelerator (E)] (E-1): 4,4'-dimethylaminopyridine

[0149] [Examples 9-16, Comparative Examples 7-12] The curing agent (B-1) was dissolved in cyclohexanone to a resin content of 40% by mass. Furthermore, the curing accelerator (E-1) was dissolved in toluene to a resin content of 5% by mass. Next, the components were prepared according to Tables 3 and 4 to obtain curable compositions. The obtained curable compositions were applied to a release PET film (a silicone-treated polyethylene terephthalate film) using a 300 μm thick, 5 cm wide applicator, dried by heating at 160°C for 1.5 hours, and then cured by heating at 200°C for 1.5 hours to obtain films that were cured products of the curable compositions. The obtained films were evaluated for dielectric properties (10 GHz), water absorption, and glass transition temperature. The results are shown in Tables 3 and 4.

[0150]

[0151]

[0152] [Evaluation Results] As can be seen from the present examples and comparative examples, the epoxy resin of this embodiment, which is a phenolic novolac type epoxy resin in which the proportion of dinuclear isomers is 50.0 to 99.9 area % as measured by gel permeation chromatography and the proportion of 2,4' isomers in the dinuclear isomers is 16.0 to 99.9 area % as measured by high performance liquid chromatography, has excellent low dielectric properties and also exhibits excellent low water absorption.

Claims

1. An epoxy resin represented by the following formula (1), in which the proportion of dinuclear units is 50.0 to 99.9 area % as measured by gel permeation chromatography, and the proportion of 2,4' isomers in the dinuclear units is 16.0 to 99.9 area % as measured by high performance liquid chromatography. (In formula (1), R １ are each independently an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, or an alkynyl group having 2 to 12 carbon atoms. Each n is independently an integer of 1 to 3, and m represents the number of repetitions and is an integer of 0 or more.

2. The epoxy resin according to claim 1, having an epoxy equivalent of 170 to 500 g / equivalent.

3. The epoxy resin described in claim 1, having a melt viscosity at 100°C of 8.0 Pa·s or less.

4. The epoxy resin according to claim 1, having a total chlorine content of 5,000 ppm by mass or less.

5. A curable composition comprising the epoxy resin according to any one of claims 1 to 4 and a curing agent.

6. The curable composition according to claim 5, comprising 0.01 to 500 parts by mass of the curing agent per 100 parts by mass of the epoxy resin.

7. The curable composition according to claim 5, wherein the curing agent is at least one selected from the group consisting of phenol-based curing agents, amide-based curing agents, imidazole-based curing agents and active ester-based curing agents.

8. A cured product of the curable composition according to claim 5.

9. An electric or electronic part comprising the curable composition according to claim 5.

10. An electric or electronic part comprising the cured product according to claim 8.

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