JP7810568B2 - Modified epoxy resin, resin composition, cured product, laminate for electric/electronic circuits, and method for producing modified epoxy resin - Google Patents

Description

The present invention relates to a modified epoxy resin with excellent solvent solubility and resin compatibility, a resin composition containing this modified epoxy resin and a curing agent, a cured product thereof with excellent heat resistance and dielectric properties, and a laminate for electrical and electronic circuits made from this resin composition.

Epoxy resins are widely used in fields such as paints, civil engineering, adhesives, and electrical materials due to their excellent heat resistance, adhesive properties, chemical resistance, water resistance, mechanical strength, and electrical properties. Furthermore, film-forming properties can be imparted by increasing their molecular weight using various methods. Such high-molecular-weight epoxy resins are called phenoxy resins. Bisphenol A-type phenoxy resins in particular are primarily used as base resins for paint varnishes and film molding, and are added to epoxy resin varnishes to adjust fluidity and improve toughness and adhesive properties when cured. Furthermore, those containing phosphorus or bromine atoms in the skeleton are used as flame retardants incorporated into epoxy resin compositions and thermoplastic resins.

Epoxy resins used in electrical materials such as laminates for electrical and electronic circuits require not only heat resistance but also solvent solubility and resin compatibility. In recent years, information devices have rapidly become smaller and more powerful, and as a result, higher performance is required than ever before from materials used in the fields of semiconductors and electronic components. In particular, low dielectric properties are required to accompany thinner and more highly functional substrates.

In response to these demands, a method has been proposed for improving heat resistance by increasing the bulk of the molecular chain and suppressing micro-Brownian motion. Patent Document 1 discloses a phenoxy resin with excellent heat resistance, produced by reacting a bulky bisphenol compound with a difunctional epoxy resin, and a cured product thereof. However, while this method can impart excellent heat resistance to the phenoxy resin and its cured product, it has the problem of not improving the dielectric properties.

Meanwhile, a method has been proposed for improving dielectric properties by converting the hydroxyl groups present in the side chains of phenoxy resins into esters using acetyl or benzoyl groups. Patent Document 2 discloses that phenoxy resins obtained by reacting a difunctional epoxy resin with a diester compound and their cured products have excellent dielectric properties, but still suffer from insufficient heat resistance. Patent Document 3 discloses that cured epoxy resins obtained by reacting a diacylated bisphenol compound with a bisphenol-type epoxy resin have low viscosity and high heat resistance, but only dicyandiamide is disclosed as a curing agent, and there is a problem of poor heat resistance when a phenol-based curing agent is used.

Japanese Patent Application Laid-Open No. 2008-231428 JP 2016-089165 A Japanese Patent Application Publication No. 8-333437

The objective of the present invention is to provide an epoxy resin with excellent solvent solubility and resin compatibility. It also aims to provide a cured product with excellent heat resistance and dielectric properties by curing a resin composition containing the epoxy resin.

In order to solve the above problems, the inventors conducted extensive research into epoxy resins and discovered that epoxy resins with a specific structure have excellent solvent solubility and resin compatibility. They also discovered that cured products obtained by curing resin compositions containing these resins have excellent heat resistance and dielectric properties, leading to the completion of the present invention.

That is, the present invention is a modified epoxy resin represented by the following formula (1) and having an epoxy equivalent of 400 to 100,000 g/eq.
In the formula, X is a divalent group and has at least a divalent group represented by the above formula (2). Y is independently a hydrogen atom, an acyl group having 2 to 20 carbon atoms, or a glycidyl group. Z is an acyl group having 2 to 20 carbon atoms or a hydrogen atom, and 5 mol% or more of Z are the above acyl groups. n is the average number of repetitions and is 1 or more and 500 or less. A is an arylene group, and ^R1 and ^R2 are independently divalent groups having a hetero element but no active hydrogen.

The present invention also provides a resin composition containing the above-mentioned modified epoxy resin and a curing agent.
The resin composition preferably contains 0.1 to 100 parts by mass of the curing agent as solid content per 100 parts by mass of the solid content of the modified epoxy resin.

The resin composition contains the modified epoxy resin, another epoxy resin, and a curing agent, and the mass ratio of the solid content of the modified epoxy resin to the other epoxy resin can be 99/1 to 1/99.
This resin composition preferably contains 0.1 to 100 parts by mass of the curing agent as solid content per 100 parts by mass of the total solid content of the modified epoxy resin and other epoxy resins.

The curing agent blended into the above resin composition is at least one selected from the group consisting of acrylic ester resins, melamine resins, urea resins, phenolic resins, acid anhydride compounds, amine compounds, imidazole compounds, amide compounds, cationic polymerization initiators, organic phosphines, polyisocyanate compounds, blocked isocyanate compounds, carbodiimide compounds, and active ester curing agents.

The present invention also relates to a cured product obtained by curing the above-mentioned resin composition.
Furthermore, the present invention relates to a laminate for electric/electronic circuits, which is made using the above resin composition.

The present invention also provides a method for producing the above-mentioned modified epoxy resin, which comprises reacting a bifunctional epoxy resin represented by the following formula (3) with a compound represented by the following formula (4):
In the formula, ^X1 and ^X2 are divalent groups, and ^X1 and/or ^X2 contain a divalent group represented by the above formula (2). G is a glycidyl group. Q is an acyl group having 2 to 20 carbon atoms or a hydrogen atom, and 5 mol% or more of Q is the above acyl group. Here, the compound represented by formula (4) may be a mixture of two or more selected from compounds in which both Qs are acyl groups, compounds in which one Q is an acyl group, and compounds in which both Qs are hydrogen atoms. m is the average number of repetitions and is 0 to 6.

The method for producing the modified epoxy resin is characterized by reacting 0.05 mol or more and 2.0 mol or less of an acid anhydride represented by the following formula (6) with 1 mol of an alcoholic hydroxyl group equivalent of the epoxy resin represented by the following formula (5):
In the formula, X is a divalent group and includes the divalent group represented by formula (2) above. L is independently a hydrogen atom or a glycidyl group. T is an acyl group having 2 to 20 carbon atoms. n is the average number of repeating units and is 1 or more and 500 or less.

The present invention provides a modified epoxy resin with excellent dielectric properties and heat resistance. Furthermore, a resin composition using this modified epoxy resin can provide a cured product with excellent dielectric properties and heat resistance. Therefore, the modified epoxy resin and resin composition of the present invention are applicable to a variety of fields, including adhesives, paints, civil engineering and construction materials, and insulating materials for electrical and electronic components. They are particularly useful in the electrical and electronic fields as insulating casting materials, laminate materials, and encapsulating materials. The phenoxy resin and resin composition containing the same of the present invention can be suitably used in multilayer printed wiring boards, laminates for electrical and electronic circuits such as capacitors, adhesives such as film adhesives and liquid adhesives, semiconductor encapsulating materials, underfill materials, interchip fill materials for 3D-LSIs, insulating sheets, prepregs, heat dissipation substrates, and the like.

1 is a GPC chart of the modified epoxy resin of Example 1. 1 is an IR chart of the modified epoxy resin of Example 1. 1 is a GPC chart of the modified epoxy resin of Example 8. 1 is an IR chart of the modified epoxy resin of Example 8. 1 is a GPC chart of the modified epoxy resin of Example 9. 1 is an IR chart of the modified epoxy resin of Example 9.

The modified epoxy resin of the present invention is an epoxy resin represented by the above formula (1) and having an epoxy equivalent (g/eq.) of 400 to 100,000, and has a structure represented by the above formula (2), in which some or all of the hydrogen atoms in the hydroxyl groups have been substituted (modified) with acyl groups (Z). If the epoxy equivalent is within the above range, the modified epoxy resin can participate in the curing reaction and be incorporated into a crosslinked structure. The epoxy equivalent is preferably 500 to 80,000, more preferably 600 to 70,000, and even more preferably 700 to 60,000.
For film applications, film-forming properties are required, so the epoxy equivalent is desirably higher, 5,000 to 100,000, more preferably 10,000 to 100,000, and even more preferably 20,000 to 100,000.
On the other hand, in applications such as substrates where the resin is used by impregnating a substrate, good impregnation properties are required, and therefore the epoxy equivalent is rather desirably low, ie, 400 to 10,000, more preferably 400 to 5,000, and even more preferably 400 to 3,000.

The weight-average molecular weight (Mw) of the modified epoxy resin of the present invention is preferably 500 or more and 200,000 or less. Here, if Mw is less than 500, there is a risk of incorporation of less of a structure that improves the heat resistance of the cured product, which is undesirable. If Mw is greater than 200,000, compatibility may decrease and handling of the resin may become difficult, which is undesirable. Furthermore, from the viewpoint of improving the film-forming properties of the modified epoxy resin, Mw is preferably 5,000 or more, more preferably 10,000 or more, and even more preferably 15,000 or more. From the viewpoint of improving compatibility and handleability, Mw is more preferably 160,000 or less, even more preferably 120,000 or less, and particularly preferably 80,000 or less. For substrate applications in which the resin is impregnated into a substrate, Mw may be 10,000 or less, more preferably 5,000 or less.
The Mw of the modified epoxy resin can be measured by the gel permeation chromatography (GPC) method described in the examples.

The modified epoxy resin of the present invention has a structure in which the hydrogen atoms in the hydroxyl groups are replaced (modified) with acyl groups, resulting in low polarity and excellent dielectric properties, as well as low moisture absorption, solvent solubility, and resin compatibility. Furthermore, the structure represented by formula (2) above results in excellent heat resistance.

The modified epoxy resin of the present invention can be advantageously obtained by the manufacturing method of the present invention. In this specification, the modified epoxy resin obtained by the manufacturing method of the present invention is sometimes referred to as the "modified epoxy resin of the present invention," the cured product obtained by curing the resin composition of the present invention is sometimes referred to as the "cured product of the present invention," and the manufacturing method of the modified epoxy resin of the present invention is sometimes referred to as the "manufacturing method of the present invention."

In the above formula (1), X is a divalent group, and is either a divalent group represented by the above formula (2) or a divalent group other than these, but the entire structure must contain a divalent group represented by formula (2). Furthermore, the divalent groups represented by formula (2) preferably account for 1 mol% or more, more preferably 10 mol% or more, even more preferably 20 mol% or more, and particularly preferably 40 mol% or more, of the total number of moles of X. Outside this range, heat resistance may be impaired.

In formula (2), A represents an arylene group, and the arylene group is not particularly limited. Examples of arylene groups include monocyclic aromatic groups such as phenylene groups and polycyclic aromatic groups such as naphthalene rings. The arylene group also includes derivatives in which the hydrogen atom bonded to the aromatic ring is substituted with a functional group such as an alkyl group, alkenyl group, alkynyl group, formyl group, alkyloxy group, alkenyloxy group, alkynyloxy group, alkylcarbonyl group, alkenylcarbonyl group, or alkynylcarbonyl group. The alkyl group is not particularly limited, and is preferably an alkyl group having 1 to 18 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms. Specific examples include methyl group, ethyl group, propyl group, butyl group, hexyl group, and decyl group. These arylene groups are preferably unsubstituted phenylene groups, unsubstituted naphthylene groups, phenylene groups having an alkyl group with 1 to 10 carbon atoms, or naphthylene groups having an alkyl group with 1 to 10 carbon atoms.

In the above formula (2), R ¹ and R ² are each independently a divalent group having no active hydrogen and having a hetero element, and have at least one hetero element in the —R ¹ —R ² — structure.

In the present invention, "active hydrogen" refers to a hydrogen atom directly bonded to any of an oxygen atom, a sulfur atom, and a nitrogen atom. These active hydrogens are highly reactive and react with various reagents. Examples of substituents having active hydrogen include -OH, -SH, -NH ₂ , -NH-, and -COOH. If active hydrogen is present in at least one of R ¹ and R ² in formula (2), gelation during production and deterioration of stability during storage may occur. For this reason, the modified epoxy resin of the present invention does not have active hydrogen in R ¹ or R ² in formula (2).

In the present invention, "heteroelement" means nitrogen, phosphorus, arsenic, antimony, oxygen, sulfur, selenium, or tellurium. Preferred examples of ^R1 and ^R2 include -O-, -N( ^R3 )- ( ^R3 : a hydrocarbon group having 1 to 10 carbon atoms), -CO-, _-SO2- , -S-, and _-PO2- . Of these, -O- and -N(Ph)- (Ph: a phenyl group) are preferred for ^R1 , and -CO- and _-SO2- are preferred for ^R2 .

Examples of the divalent group represented by the formula (2) include, but are not limited to, the divalent groups represented by the following formulas (2a) to (2i). Among these, (2a), (2b), (2c), (2d), (2g), (2h), and (2i) are preferred, and (2
More preferred are (2a), (2c), (2d), (2g), (2h), and (2i), and even more preferred are (2a), (2c), (2g), (2h), and (2i).

The divalent group other than the divalent group structure represented by formula (2) is preferably a divalent hydrocarbon group or a hydrocarbon group which may have in the hydrocarbon chain a group such as -O-, -CO-, -S-, -COO-, -SO-, -SO ₂ -, etc. Examples of these divalent groups include an aromatic skeleton representing the residual skeleton obtained by removing two hydroxyl groups from an aromatic diol compound, an aliphatic skeleton representing the residual skeleton obtained by removing two hydroxyl groups from an aliphatic diol compound, and an alicyclic skeleton representing the residual skeleton obtained by removing two hydroxyl groups from an alicyclic diol compound.
These groups are derived from the residual skeleton obtained by removing two glycidyloxy groups from a bifunctional epoxy resin (diglycidyl ether compound), the residual skeleton obtained by removing two ester structures from a diester compound, and the residual skeleton obtained by removing two hydroxyl groups from a bifunctional phenol compound.

Specific examples of aromatic skeletons with two hydroxyl groups removed from an aromatic diol compound include bisphenol-type compounds, such as bisphenol A, bisphenolacetophenone, bisphenol AF, bisphenol AD, bisphenol B, bisphenol BP, bisphenol C, bisphenol E, bisphenol F, bisphenol G, bisphenol M, bisphenol S, bisphenol P, bisphenol PH, bisphenoltrimethylcyclohexane, and bisphenolcyclohexane, which may be unsubstituted or substituted with an alkyl group having 1 to 10 carbon atoms; benzene-type compounds, such as dihydroxyphenyls, such as hydroquinone, resorcinol, and catechol, which may be unsubstituted or substituted with an alkyl group having 1 to 10 carbon atoms; naphthalene-type compounds, such as dihydroxynaphthalenes, which may be substituted with an alkyl group having 1 to 10 carbon atoms; biphenyl-type compounds, such as dihydroxybiphenyls, which may be substituted with an alkyl group having 1 to 10 carbon atoms; and bisphenolfluorene and fluorene-type compounds such as bisphenolfluorenes and bisnaphtholfluorenes, which may be unsubstituted or have an alkyl group having 1 to 10 carbon atoms as a substituent, such as biscresolfluorene; 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-HQ), 10-(2,7-dihydroxynaphthyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-NQ), 10-(1 Examples include phosphorus-containing phenols that may be unsubstituted or have an alkyl group, aryl group, or aralkyl group having 1 to 10 carbon atoms as a substituent, such as 1,4-dihydroxy-2-naphthyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide, diphenylphosphinylhydroquinone, diphenylphosphinyl-1,4-dioxynaphthalene, 1,4-cyclooctylenephosphinyl-1,4-phenyldiol, and 1,5-cyclooctylenephosphinyl-1,4-phenyldiol.

Specific examples of the aliphatic skeleton include alkylene glycol skeletons such as ethylene glycol, propylene glycol, and butylene glycol.

Specific examples of the alicyclic skeleton include hydrogenated bisphenol skeletons such as hydrogenated bisphenol A, hydrogenated bisphenol F, and hydrogenated bisphenol acetophenone.

In formula (1), Y is independently a hydrogen atom, an acyl group having 2 to 20 carbon atoms, or a glycidyl group. When Y is a hydrogen atom, a hydroxyl group is provided at the terminal; when Y is an acyl group, an ester group is provided at the terminal; and when Y is a glycidyl group, an epoxy group is provided at the terminal. An acyl group is represented by R-CO-, where R is a hydrocarbon group having 1 to 19 carbon atoms. It is advisable to control the proportion of these terminal groups depending on the application.
In the acyl group (R—CO—), the hydrocarbon group having 1 to 19 carbon atoms represented by R is preferably an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 13 carbon atoms.
The alkyl group having 1 to 12 carbon atoms may be linear, branched, or cyclic, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a t-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, a t-pentyl group, a cyclopentyl group, an n-hexyl group, an isohexyl group, a cyclohexyl group, an n-heptyl group, a cycloheptyl group, a methylcyclohexyl group, an n-octyl group, a cyclooctyl group, an n-nonyl group, a 3,3,5-trimethylcyclohexyl group, an n-decyl group, a cyclodecyl group, an n-undecyl group, an n-dodecyl group, and a cyclododecyl group.
Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a tolyl group, an ethylphenyl group, a xylyl group, an n-propylphenyl group, an isopropylphenyl group, a mesityl group, a naphthyl group, and a methylnaphthyl group.
Examples of aralkyl groups having 7 to 13 carbon atoms include, but are not limited to, benzyl, methylbenzyl, dimethylbenzyl, trimethylbenzyl, phenethyl, 2-phenylisopropyl, and naphthylmethyl groups.
Among these, acyl groups having a hydrocarbon group of 1 to 7 carbon atoms are more preferred, with acetyl, propanoyl, butanoyl, benzoyl and methylbenzoyl groups being even more preferred, and acetyl and benzoyl groups being particularly preferred.

In formula (1), Z is an acyl group having 2 to 20 carbon atoms or a hydrogen atom. 5 mol % or more of Z are acyl groups, and the remainder are hydrogen atoms. 10 mol % or more, preferably 50 mol % or more, more preferably 70 mol % or more, and even more preferably 90 mol % or more of Z are acyl groups. On the other hand, the upper limit is 100%, but in terms of the reaction, it may be substantially about 95%. The acyl groups are the same as those exemplified for Y above, and the preferred acyl groups are also the same.
When all Z's (100 mol%) are acyl groups, the modified epoxy resin of the present invention does not contain secondary hydroxyl groups, and the dielectric properties and moisture resistance can be further improved. On the other hand, for example, when fine-tuning the adhesion to metals, it is possible to intentionally allow an appropriate amount of secondary hydroxyl groups to be present in the modified epoxy resin of the present invention by leaving some of the Z's as hydrogen atoms, as long as this does not significantly affect other physical properties such as moisture resistance.

In formula (1), n is the number of repeats and is an average value. Its value ranges from 1 to 500. From the viewpoint of moldability and handleability, it is preferably from 1 to 400, and more preferably from 1 to 300. The number n can be calculated from the number average molecular weight (Mn) obtained by GPC.

The modified epoxy resin of the present invention is one in which some or all of the secondary hydroxyl groups are acylated, and can be obtained by various methods. Preferred production methods include, for example, the following production method.
(A): A production method in which a bifunctional epoxy resin represented by the above formula (3) is reacted with a diester compound and/or a bifunctional phenol compound represented by the above formula (4). Hereinafter, this method may be referred to as production method (A).
(B): A production method in which an epoxy resin represented by the above formula (5) (sometimes referred to as epoxy resin (a) to distinguish it from the modified epoxy resin of the present invention) is reacted with an acid component (acylating agent) such as an acid anhydride of an organic acid, an organic acid halide, or an organic acid ester. Hereinafter, this method may be referred to as production method (B).
The modified epoxy resins obtained by the production methods (A) and (B) are the modified epoxy resins of the present invention and are represented by the same formula (1).

The above-mentioned production method (A) is a method in which a bifunctional epoxy resin represented by formula (3) is reacted with a compound represented by formula (4).
In the above formula (3), G is a glycidyl group, m is the number of repetitions, the average value of which is 0 or more and 6 or less, and preferably 0 or more and 3 or less.
In formula (4), Q is an acyl group having 2 to 20 carbon atoms.
In formula (4), 5 mol % or more of Q are acyl groups having 2 to 20 carbon atoms, and the remainder are hydrogen atoms. Here, the compound represented by formula (4) may be a mixture of two or more compounds selected from diester compounds in which both Qs are acyl groups, monoester compounds in which one Q is an acyl group and the other is a hydrogen atom, and diphenol compounds in which both Qs are hydrogen atoms. The compound represented by formula (4) is called a diester compound. The diester compound may be a diester compound in which both Qs are acyl groups, or a compound (mixture) in which the main component (50% or more) is such a compound.

^X1 in formula (3) and ^X2 in formula (4) are selected so as to give X in formula (1). Therefore, it is preferred that either the epoxy resin represented by formula (3) or the compound represented by formula (4), or both, contain a divalent group represented by formula (2), and that this group is contained in an amount of 1 to 100 mol % based on the total number of moles of ^X1 and ^X2 . From the viewpoint of fully exhibiting the heat resistance attributable to the divalent group represented by formula (2), the divalent group represented by formula (2) is more preferably 10 mol % or more, even more preferably 20 mol % or more, and particularly preferably 40 mol % or more.
The modified epoxy resin of the present invention necessarily contains a divalent group represented by formula (2), and as long as this requirement is met, the structure of formula (2) may be contained in either the starting bifunctional epoxy resin and/or the compound represented by formula (4), and the proportion thereof is not limited. Furthermore, when ^X1 in formula (3) or ^X2 in formula (4) does not contain a divalent group represented by formula (2), another divalent group can be introduced into ^X1 or ^X2 .

The bifunctional epoxy resin used in Production Method (A) of the present invention is an epoxy resin represented by the above formula (3), and examples thereof include an epoxy resin obtained by reacting a bifunctional phenol compound represented by HO-X ¹ -OH with epihalohydrin in the presence of an alkali metal compound, where X ¹ is the same as X ¹ in the above formula (3).

The raw material epoxy resin represented by formula (3) preferably has an epoxy equivalent of 100 to 400 g/eq., more preferably 300 g/eq. or less. The m value in formula (3) is preferably 0 to 1, more preferably 0.3 or less.

Examples of epihalohydrins include epichlorohydrin and epibromohydrin.
Examples of alkali metal compounds include alkali metal hydroxides such as sodium hydroxide, lithium hydroxide, and potassium hydroxide; alkali metal salts such as sodium carbonate, sodium bicarbonate, sodium chloride, lithium chloride, and potassium chloride; alkali metal alkoxides such as sodium methoxide and sodium ethoxide; alkali metal salts of organic acids such as sodium acetate and sodium stearate; alkali metal phenoxides, sodium hydride, and lithium hydride.

When reacting a bifunctional phenolic compound with epihalohydrin to obtain the starting epoxy resin, an alkali metal compound is used in an amount of 0.80 to 1.20 times by mole, preferably 0.85 to 1.05 times by mole, relative to the functional groups in the bifunctional phenolic compound. Less than this amount is undesirable, as the amount of residual hydrolyzable chlorine increases. The alkali metal compound is used in the form of an aqueous solution, alcohol solution, or solid.

During the epoxidation reaction, an excess amount of epihalohydrin is used relative to the bifunctional phenolic compound. Typically, 1.5 to 15 moles of epihalohydrin are used per mole of functional group in the bifunctional phenolic compound, preferably 2 to 10 moles, and more preferably 5 to 8 moles. If the amount is greater than this, production efficiency will decrease, and if it is less than this, the amount of high-molecular-weight epoxy resin produced will increase, making it unsuitable as a raw material.

The epoxidation reaction is usually carried out at a temperature of 120°C or less. If the reaction temperature is high, the amount of so-called difficult-to-hydrolyze chlorine increases, making it difficult to achieve high purity. The temperature is preferably 100°C or less, and more preferably 85°C or less.

When the above-mentioned bifunctional phenol compound is reacted with epihalohydrin, m usually becomes greater than 0. To achieve m of 0, an epoxy resin produced by a known method can be highly purified by distillation, crystallization, or the like, or the above-mentioned bifunctional phenol compound can be allylated and then epoxidized by oxidizing the olefin moiety.

The diester compound used in production method (A) of the present invention can be obtained, for example, by acylation of the bifunctional phenol compound described above through a condensation reaction with an acid anhydride of an organic acid, a halide of an organic acid, or an organic acid.

By using an epoxy resin in which m in formula (3) is 0 as the raw material, the modified epoxy resin of the present invention will not contain secondary hydroxyl groups, thereby further improving its dielectric properties and moisture resistance. Furthermore, for example, when fine-tuning adhesion to metals, by using an epoxy resin with an appropriate m number, it is possible to intentionally include an appropriate amount of secondary hydroxyl groups in the modified epoxy resin of the present invention, as long as this does not significantly affect moisture resistance or other physical properties.

The amounts of the bifunctional epoxy resin and diester compound used need to be adjusted depending on the epoxy equivalent of the desired modified epoxy resin, but a ratio of 0.3 to 1.0 equivalents of ester groups per equivalent of epoxy groups is preferred. This equivalent ratio facilitates high molecular weight formation with epoxy groups at the molecular terminals. It is also possible to replace a portion of the diester compound with the bifunctional phenol compound. As described above, this allows for the presence of an appropriate amount of secondary hydroxyl groups in the modified epoxy resin of the present invention, allowing for fine adjustment of physical properties.
In the production method (A), a polymerization reaction and an esterification reaction of secondary hydroxyl groups occur, resulting in an increase in Mw and the production of a modified epoxy resin.

In production method (A), a catalyst may be used. The catalyst may be any compound that has catalytic activity that promotes the reaction between the epoxy group and the ester group. Examples of the catalyst include tertiary amines, cyclic amines, imidazoles, organic phosphorus compounds, and quaternary ammonium salts. These catalysts may be used alone or in combination of two or more.

Examples of tertiary amines include, but are not limited to, triethylamine, tri-n-propylamine, tri-n-butylamine, triethanolamine, benzyldimethylamine, and 2,4,6-tris(dimethylaminomethyl)phenol.

Examples of cyclic amines include, but are not limited to, 1,4-diazabicyclo[2,2,2]octane (DABCO), 1,8-diazabicyclo[5,4,0]undecene-7 (DBU), 1,5-diazabicyclo[4,3,0]nonene-5 (DBN), N-methylmorpholine, pyridine, and N,N-dimethylaminopyridine (DMAP).

Examples of imidazoles include, but are not limited to, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, and 1-benzyl-2-phenylimidazole.

Examples of organic phosphorus compounds include phosphines such as tri-n-propylphosphine, tri-n-butylphosphine, diphenylmethylphosphine, triphenylphosphine, tris(p-tolyl)phosphine, tricyclohexylphosphine, tri(t-butyl)phosphine, tris(p-methoxyphenyl)phosphine, paramethylphosphine, 1,2-bis(dimethylphosphino)ethane, and 1,4-bis(diphenylphosphino)butane; tetramethylphosphonium bromide, tetramethylphosphonium iodide, tetramethylphosphonium hydroxide, tetrabutylphosphonium hydroxide, and tetramethylphosphonium iodide. Examples of phosphonium salts include, but are not limited to, trimethylcyclohexylphosphonium chloride, trimethylcyclohexylphosphonium bromide, trimethylbenzylphosphonium chloride, trimethylbenzylphosphonium bromide, tetraphenylphosphonium bromide, triphenylmethylphosphonium bromide, triphenylmethylphosphonium iodide, triphenylethylphosphonium chloride, triphenylethylphosphonium bromide, triphenylethylphosphonium iodide, triphenylbenzylphosphonium chloride, and triphenylbenzylphosphonium bromide.

Examples of quaternary ammonium salts include, but are not limited to, tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium hydroxide, triethylmethylammonium chloride, tetraethylammonium chloride, tetraethylammonium bromide, tetraethylammonium iodide, tetrapropylammonium bromide, tetrapropylammonium hydroxide, tetrabutylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium iodide, benzyltrimethylammonium chloride, benzyltrimethylammonium bromide, benzyltrimethylammonium hydroxide, benzyltributylammonium chloride, and phenyltrimethylammonium chloride.

Among the catalysts listed above, 4-(dimethylamino)pyridine, 1,4-diazabicyclo[2.2.2]octane, 1,8-diazabicyclo[5.4.0]undecene-7, 1,5-diazabicyclo[4.3.0]nonene-5, 2-ethyl-4-methylimidazole, tris(p-tolyl)phosphine, tricyclohexylphosphine, tri(t-butyl)phosphine, and tris(p-methoxyphenyl)phosphine are preferred, with 4-(dimethylamino)pyridine, 1,8-diazabicyclo[5.4.0]undecene-7, 1,5-diazabicyclo[4.3.0]nonene-5, and 2-ethyl-4-methylimidazole being particularly preferred.

The amount of catalyst used is typically 0.001 to 1% by mass of the reaction solids. However, when these compounds are used as catalysts, the catalyst may remain as residue in the resulting modified epoxy resin, potentially deteriorating the insulating properties of the printed wiring board and shortening the pot life of the composition. Therefore, the nitrogen content derived from the catalyst in the modified epoxy resin is preferably 0.5% by mass or less, more preferably 0.3% by mass or less. Furthermore, the phosphorus content derived from the catalyst in the modified epoxy resin is preferably 0.5% by mass or less, more preferably 0.3% by mass or less.

In production method (A), a reaction solvent may be used. Any solvent that dissolves the modified epoxy resin may be used. Examples include aromatic solvents, ketone solvents, amide solvents, glycol ether solvents, and ester solvents. These solvents may be used alone or in combination of two or more.

Aromatic solvents include, for example, benzene, toluene, and xylene.

Examples of ketone solvents include acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, 2-heptanone, 4-heptanone, 2-octanone, cyclohexanone, acetylacetone, diisobutyl ketone, isophorone, methylcyclohexanone, and acetophenone.

Examples of amide solvents include formamide, N-methylformamide, N,N-dimethylformamide (DMF), acetamide, N-methylacetamide, N,N-dimethylacetamide, 2-pyrrolidone, and N-methylpyrrolidone.

Examples of glycol ether solvents include ethylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol mono-n-butyl ether; diethylene glycol dialkyl ethers such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol mono-n-butyl ether; propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, and propylene glycol mono-n-butyl ether; ethylene glycol dialkyl ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and ethylene glycol dibutyl ether; polyethylene glycol dialkyl ethers such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, and triethylene glycol dibutyl ether; and propylene glycol dialkyl ethers such as propylene glycol dimethyl ether, propylene glycol diethyl ether, and propylene glycol dibutyl ether. Examples of suitable alkyl ethers include glycol dialkyl ethers, polypropylene glycol dialkyl ethers such as dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol dibutyl ether, tripropylene glycol dimethyl ether, tripropylene glycol diethyl ether, and tripropylene glycol dibutyl ether, ethylene glycol monoalkyl ether acetates such as ethylene glycol monoethyl ether acetate, ethylene glycol monoethyl ether acetate, and ethylene glycol monobutyl ether acetate, polyethylene glycol monoalkyl ether acetates such as diethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, triethylene glycol monomethyl ether acetate, triethylene glycol monoethyl ether acetate, and triethylene glycol monobutyl ether acetate, and propylene glycol monoalkyl ether acetates such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and propylene glycol monobutyl ether acetate.

Examples of ester solvents include methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, benzyl acetate, ethyl propionate, ethyl butyrate, butyl butyrate, valerolactone, and butyrolactone.

Other solvents include, for example, dioxane, dimethyl sulfoxide, sulfolane, and gamma-butyrolactone.

In production method (A), the solids concentration during the reaction is preferably 35 to 95% by mass. It is more preferably 50 to 90% by mass, and even more preferably 70 to 90% by mass. If a highly viscous product is produced during the reaction, additional solvent can be added to continue the reaction. After the reaction is complete, the solvent can be removed or further added as necessary.

The reaction temperature is set within a range that does not decompose the catalyst used. If the reaction temperature is too high, the catalyst may decompose, stopping the reaction or degrading the resulting modified epoxy resin. If the reaction temperature is too low, the reaction may not proceed sufficiently and the target molecular weight may not be achieved. Therefore, the reaction temperature is preferably 50 to 230°C, more preferably 120 to 200°C. The reaction time is usually 1 to 12 hours, preferably 3 to 10 hours. When using a low-boiling solvent such as acetone or methyl ethyl ketone, the reaction temperature can be maintained by conducting the reaction under high pressure using an autoclave. If the heat of reaction needs to be removed, this is usually done by evaporating, condensing, or refluxing the solvent using the heat of reaction, by indirect cooling, or by a combination of these.

Next, the production method (B) of the present invention will be described.
Production method (B) is a method for obtaining a modified epoxy resin represented by formula (1) having an epoxy equivalent of 400 to 100,000 g/eq., i.e., the modified epoxy resin of the present invention, by reacting an epoxy resin represented by formula (5) with 0.05 to 2.0 moles of an acid anhydride represented by formula (6) per mole of alcoholic hydroxyl group equivalent of the epoxy resin.

The epoxy resin (a) represented by the formula (5) as a raw material essentially contains a divalent group represented by the formula (2) in X of the formula (5).
This epoxy resin (a) can be obtained by a conventionally known method. For example, it can be produced by reacting a bifunctional phenol compound having the structure represented by the above formula (2) (sometimes referred to as "bifunctional phenol compound (a)") with epihalohydrin in the presence of an alkali metal compound (hereinafter referred to as "one-step method"). It can also be produced by reacting a bifunctional epoxy resin having the structure represented by the above formula (2) with a bifunctional phenol compound in the presence of a catalyst (hereinafter referred to as "two-step method"). Epoxy resin (a) can be obtained by either method.

The weight average molecular weight and epoxy equivalent of epoxy resin (a) can be produced within the desired range by appropriately adjusting the molar ratio of the epihalohydrin and bifunctional phenol compound used in the one-stage process, or the molar ratio of the bifunctional epoxy resin and bifunctional phenol compound used in the two-stage process.

Examples of the bifunctional phenol compound (a) used in the one-step and two-step production methods include phenolphthalein and phenolphthalein anilide containing a divalent group represented by the above formula (2).

Other bifunctional phenol compounds may also be used in combination as long as the object of the present invention is not impaired. Examples of bifunctional phenol compounds that may be used in combination include bisphenols such as bisphenol A, bisphenol F, bisphenol S, bisphenol B, bisphenol E, bisphenol C, bisphenolacetophenone, bisphenolfluorene, dihydroxybiphenyl ether, and dihydroxybiphenyl thioether, biphenols such as 4,4'-biphenol and 2,4'-biphenol, dihydroxynaphthalene, hydroquinone, catechol, resorcinol, 1,1-bi-2-naphthol, 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-HQ), and 10-(2,7-dihydroxynaphthyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-NQ).
In addition, a plurality of types of these bifunctional phenol compounds may be used in combination.

First, the one-stage method will be described.
In the one-step process, a bifunctional phenol compound and an epihalohydrin are reacted in a non-reactive solvent in the presence of an alkali metal compound, and the epihalohydrin is consumed to cause a condensation reaction to obtain epoxy resin (a). After completion of the reaction, it is necessary to remove the by-product salt by filtration or washing with water. Examples of the alkali metal compound include the same alkali metal compounds as those used in the production of the bifunctional epoxy resin represented by formula (3) used in production method (A) of the present invention.
The weight average molecular weight and epoxy equivalent of the epoxy resin (a) can be adjusted to fall within the desired range by appropriately adjusting the molar ratio of the bifunctional phenol compound and epihalohydrin charged.
For example, when the weight average molecular weight of the epoxy resin (a) is set to 10,000 or more, the amount of epihalohydrin is adjusted to 0.985 to 1.015 moles, preferably 0.99 to 1.012 moles, and more preferably 0.995 to 1.01 moles, per mole of the bifunctional phenol compound. Furthermore, when the epoxy equivalent of the epoxy resin (a) is set to 5,000 g/eq. or less, the amount of epihalohydrin is adjusted to 1.015 to 8 moles, preferably 1.05 to 6 moles, and more preferably 1.1 to 5 moles, per mole of the bifunctional phenol compound.

The molar amount of the bifunctional phenol compound (a) used as a raw material is preferably 1 mol% or more, more preferably 10 mol% or more, even more preferably 20 mol% or more, and particularly preferably 40 mol% or more, of the total bifunctional phenol compounds. Outside this range, the heat resistance of the modified epoxy resin of the present invention may be impaired.

This reaction can be carried out under normal pressure or reduced pressure. For reactions under normal pressure, the reaction temperature is typically 20 to 200°C, more preferably 30 to 170°C, even more preferably 40 to 150°C, and particularly preferably 50 to 100°C. For reactions under reduced pressure, the temperature is preferably 20 to 100°C, more preferably 30 to 90°C, and even more preferably 35 to 80°C. A reaction temperature within this range makes it difficult for side reactions to occur and facilitates the reaction to proceed. The reaction pressure is typically normal pressure. Furthermore, if heat of reaction needs to be removed, this is typically accomplished by evaporation/condensation/refluxing the solvent used using the reaction heat, indirect cooling, or a combination of these.

In addition to the reaction solvents exemplified in Production Method (A) of the present invention, alcohols such as ethanol, isopropyl alcohol, and butyl alcohol can also be used as reactive solvents. They may be used alone or in combination of two or more.

Next, the two-stage method will be described.
The bifunctional epoxy resin used as the starting epoxy resin in the two-stage process is the same as the bifunctional epoxy resin represented by the above formula (3) used in the production process (A) of the present invention.

The bifunctional epoxy resin used as the raw material for the two-stage process is preferably the bifunctional epoxy resin represented by formula (3) above. However, other bifunctional epoxy resins may be used in combination as long as the objectives of the present invention are not impaired. Examples of bifunctional epoxy resins that can be used in combination include bisphenol-type epoxy resins such as bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol S-type epoxy resins, bisphenolacetophenone-type epoxy resins, diphenyl sulfide-type epoxy resins, and diphenyl ether-type epoxy resins; biphenol-type epoxy resins; diphenyldicyclopentadiene-type epoxy resins; alkylene glycol-type epoxy resins; and aliphatic cyclic epoxy resins. These epoxy resins may be substituted with non-detrimental substituents such as alkyl groups and aryl groups. Multiple types of these epoxy resins may be used in combination.

In the two-stage process, a catalyst can be used, and any compound with catalytic activity that promotes the reaction between the epoxy group and the phenolic hydroxyl group can be used. Examples include the same catalysts as those exemplified in Production Method (A) of the present invention. The alkali metal compounds used in the production of the bifunctional epoxy resin represented by Formula (3) above can also be used. These catalysts may be used alone or in combination of two or more types. The amount used is also the same as the amount exemplified in Production Method (A) of the present invention.

In the two-stage process, a solvent may be used. Any solvent may be used as long as it dissolves the epoxy resin and does not adversely affect the reaction. Examples of such solvents include the same solvents as those exemplified in Production Method (A) of the present invention. These solvents may be used alone or in combination of two or more.

The amount of solvent used can be selected appropriately depending on the reaction conditions. For example, in the case of a two-stage process, a solids concentration of 35 to 95% by mass is preferred. Furthermore, if a highly viscous product is produced during the reaction, the reaction can be continued by adding solvent midway through the reaction. After the reaction is complete, the solvent can be removed by distillation or other methods, or more solvent can be added, as needed.

The reaction temperature should be within a range that does not decompose the catalyst used. If the reaction temperature is too high, the catalyst may decompose, stopping the reaction or degrading the resulting epoxy resin. If the reaction temperature is too low, the reaction may not proceed sufficiently to achieve the desired molecular weight. Therefore, the reaction temperature is preferably 50 to 230°C, more preferably 100 to 210°C, and even more preferably 120 to 200°C. The reaction time is usually 1 to 12 hours, with 3 to 10 hours being preferred. When using a low-boiling solvent such as acetone or methyl ethyl ketone, the reaction temperature can be maintained by conducting the reaction under high pressure using an autoclave. If the heat of reaction needs to be removed, this is usually done by evaporating, condensing, or refluxing the solvent using the heat of reaction, indirect cooling, or a combination of these.

The modified epoxy resin of the present invention can be obtained by acylation of the hydroxyl groups in the epoxy resin (a) represented by formula (5) obtained in this manner. Acylation can be achieved not only by direct esterification, but also by methods such as transesterification.

The acid component used in the acylation may be, for example, organic acids such as acetic acid, propionic acid, butyric acid, isobutyric acid, pentanoic acid, octanoic acid, caprylic acid, lauric acid, stearic acid, oleic acid, benzoic acid, t-butylbenzoic acid, hexahydrobenzoic acid, phenoxyacetic acid, acrylic acid, or methacrylic acid, as well as acid anhydrides of organic acids, organic acid halides, and organic acid esters.

Examples of the acid anhydrides of organic acids include acetic anhydride, benzoic anhydride, and phenoxyacetic anhydride.
Examples of organic acid esters include methyl acetate, ethyl acetate, butyl acetate, methyl benzoate, ethyl benzoate, etc. Examples of organic acid halides include acetic acid chloride, benzoic acid chloride, phenoxyacetic acid chloride, etc.

Preferred compounds for use in esterification include organic acid halides such as acetic acid chloride, benzoic acid chloride, and phenoxyacetic acid chloride, as well as acid halides and organic acid anhydrides such as acetic anhydride, benzoic acid anhydride, and phenoxyacetic acid anhydride. Acid anhydrides such as acetic anhydride and benzoic acid anhydride are more preferred, as they do not require water washing after esterification and avoid the inclusion of halogens, which are undesirable in electrical materials applications.

When reacting the acid component, such as the organic acid, acid anhydride of an organic acid, organic acid halide, or organic acid ester, used to esterify the hydroxyl groups of epoxy resin (a), with epoxy resin (a), the charging ratio may be the same as the target esterification ratio, or if the reactivity is low, the acid component may be charged in excess relative to the hydroxyl groups, and after reaction to the target esterification ratio, the unreacted acid component may be removed.

When directly esterifying with an acid component, it can be carried out while dehydrating using various esterification catalysts, such as acid catalysts such as paratoluenesulfonic acid and phosphoric acid, or metal catalysts such as tetraisopropyl titanate, tetrabutyl titanate, dibutyltin oxide, dioctyltin oxide, and zinc chloride. It is usually carried out under a nitrogen atmosphere at 100 to 250°C, and more preferably 130 to 230°C.

When an acid halide or acid anhydride is used for esterification, the resulting acid can be removed by any of the following methods: neutralizing with a basic compound and then filtering the salt; neutralizing with a basic compound and then washing with water; washing with water without neutralization; or removing the acid by distillation or adsorption. These methods may also be used in combination. When removing an acid with a lower boiling point than the reaction solvent, it is preferable to remove it by distillation.

When epoxy resin (a) is esterified by transesterification, it is generally desirable to carry out the esterification under a nitrogen atmosphere while dealcoholizing using a known esterification catalyst, such as dibutyltin oxide, dioctyltin oxide, stannoxane catalyst, tetraisopropyl titanate, tetrabutyl titanate, lead acetate, zinc acetate, or antimony trioxide, or an organometallic catalyst, an acid catalyst, such as hydrochloric acid, sulfuric acid, phosphoric acid, or sulfonic acid, or a basic catalyst, such as lithium hydroxide or sodium hydroxide.

In production method (B) of the present invention, a reaction solvent may be used, and any solvent that dissolves the epoxy resin may be used. Examples include the solvents exemplified in production method (A) of the present invention. These solvents may be the same as or different from those used in preparing epoxy resin (a). They may be used alone or in combination of two or more. The solids concentration during the reaction is the same as in production method (A), and is preferably 35 to 95% by mass, more preferably 50 to 90% by mass, and even more preferably 70 to 90% by mass.

The resin composition of the present invention is a resin composition containing at least the modified epoxy resin of the present invention and a curing agent. Furthermore, various additives such as epoxy resins, inorganic fillers, coupling agents, and antioxidants can be appropriately blended into the resin composition of the present invention as needed. The resin composition of the present invention provides a cured product that fully satisfies the various physical properties required for various applications.

A resin composition can be prepared by blending a curing agent with the modified epoxy resin of the present invention. In this invention, the term "curing agent" refers to a substance that contributes to the crosslinking reaction and/or chain extension reaction with the modified epoxy resin. In this invention, even substances that are normally called "curing accelerators" are considered to be curing agents as long as they contribute to the crosslinking reaction and/or chain extension reaction of the modified epoxy resin.

The content of the curing agent in the resin composition of the present invention is preferably 0.1 to 100 parts by mass in terms of solids, per 100 parts by mass of the solids of the modified epoxy resin of the present invention. It is more preferably 80 parts by mass or less, and even more preferably 60 parts by mass or less.

When the resin composition of the present invention contains other epoxy resins described below, the weight ratio of the solids of the modified epoxy resin of the present invention to the other epoxy resins is 99/1 to 1/99. In this invention, "solids" refers to components excluding solvent, and includes not only solid modified epoxy resins and other epoxy resins, but also semi-solid and viscous liquids. Furthermore, "resin components" refers to the total of the modified epoxy resin of the present invention and the other epoxy resins described below.

The curing agent used in the resin composition of the present invention is not particularly limited, and any commonly known epoxy resin curing agent can be used. From the perspective of improving heat resistance, preferred curing agents include phenol-based curing agents, amide-based curing agents, imidazoles, and active ester-based curing agents. These curing agents may be used alone or in combination of two or more types.

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, 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, allylated pyrogallol, and the like.

Examples of amide-based curing agents include dicyandiamide and its derivatives, polyamide resins, etc.

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 Examples of imidazoles include 2,4-diamino-6-[2'-ethyl-4'-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, and adducts of epoxy resins with the above imidazoles. Because imidazoles have catalytic activity, they can generally be classified as curing accelerators, as described below, but in the present invention they are classified as curing agents.

Preferred active ester curing agents are compounds containing two or more highly reactive ester groups per molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds. Among these, phenol esters obtained by reacting a carboxylic acid compound with an aromatic compound containing a phenolic hydroxyl group are more preferred. Specific examples of carboxylic acid compounds include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid. Examples of aromatic compounds containing a phenolic hydroxyl group include catechol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadienyldiphenol, and phenol novolac.

Other curing agents that can be used in the resin composition of the present invention include, for example, amine-based curing agents, 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, carbodiimide compounds, etc. These other curing agents may be used alone, or two or more may be mixed in any combination and ratio.

The resin composition of the present invention can contain epoxy resins other than the modified epoxy resin of the present invention. The use of other epoxy resins can compensate for insufficient physical properties or improve various physical properties. The epoxy resin preferably has two or more epoxy groups in the molecule, and more preferably has three or more epoxy groups. Examples include polyglycidyl ether compounds, polyglycidyl amine compounds, polyglycidyl ester compounds, alicyclic epoxy compounds, and other modified epoxy resins. These epoxy resins can be used alone, or two or more types of epoxy resins of the same type can be used in combination, or epoxy resins of different types can be used in combination.

Examples of the polyglycidyl ether compound include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol AF type epoxy resins, bisphenol Z type epoxy resins, bisphenol fluorene type epoxy resins, diphenyl sulfide type epoxy resins, diphenyl ether type epoxy resins, naphthalene type epoxy resins, hydroquinone type epoxy resins, resorcinol type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, alkyl novolac type epoxy resins, styrenated phenol novolac type epoxy resins, bisphenol novolac type epoxy resins, naphthol novolac type epoxy resins, phenol aralkyl type epoxy resins, β-naphthol aralkyl type epoxy resins, naphthalenediol aralkyl type epoxy resins, α-naphthol aralkyl type epoxy resins, biphenyl aralkyl phenol type epoxy resins, biphenyl type epoxy resins, triphenylmethane type epoxy resins, dicyclopentadiene type epoxy resins, alkylene glycol type epoxy resins, and various epoxy resins such as aliphatic cyclic epoxy resins can be used.

Examples of polyglycidylamine compounds include diaminodiphenylmethane-type epoxy resins, metaxylenediamine-type epoxy resins, 1,3-bisaminomethylcyclohexane-type epoxy resins, isocyanurate-type epoxy resins, aniline-type epoxy resins, hydantoin-type epoxy resins, and aminophenol-type epoxy resins.

Examples of polyglycidyl ester compounds include dimer acid type epoxy resins, hexahydrophthalic acid type epoxy resins, and trimellitic acid type epoxy resins.

Examples of alicyclic epoxy compounds include aliphatic cyclic epoxy resins such as Celloxide 2021 (manufactured by Daicel Chemical Industries, Ltd.).

Other modified epoxy resins include, for example, urethane-modified epoxy resins, oxazolidone ring-containing epoxy resins, epoxy-modified polybutadiene rubber derivatives, carboxyl-terminated butadiene nitrile rubber (CTBN)-modified epoxy resins, polyvinylarene polyoxides (e.g., divinylbenzene dioxide, trivinylnaphthalene trioxide), and phenoxy resins.

When the resin composition of the present invention uses the modified epoxy resin of the present invention together with another epoxy resin, the amount of the modified epoxy resin in the solid content of the modified epoxy resin and all epoxy resin components is preferably 1 to 99% by mass, more preferably 50% by mass or more, and even more preferably 80% by mass or more.

The resin composition of the present invention may contain a solvent or reactive diluent to adjust the viscosity of the resin composition appropriately when handling it to form a coating film. In the resin composition of the present invention, the solvent or reactive diluent is used to ensure ease of handling and workability when molding the resin composition, and there are no particular restrictions on the amount used. In this invention, the terms "solvent" and the aforementioned "solvent" are used separately depending on the form of use, but the same or different substances may be used independently.

Examples of solvents that may be contained in the resin composition of the present invention 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 above-listed solvents may be used alone, or two or more may be mixed in any combination and ratio.

Examples of reactive diluents include monofunctional glycidyl ethers such as allyl glycidyl ether, bifunctional glycidyl ethers such as propylene glycol diglycidyl ether, polyfunctional glycidyl ethers such as trimethylolpropane polyglycidyl ether, glycidyl esters, and glycidyl amines.

These solvents or reactive diluents are preferably used in an amount of 90% by mass or less based on nonvolatile content, with the appropriate type and amount selected depending on the application. For example, for printed wiring board applications, polar solvents with a boiling point of 160°C or less, such as methyl ethyl ketone, acetone, or 1-methoxy-2-propanol, are preferred, with the amount used being 40 to 80% by mass based on nonvolatile content. For adhesive film applications, ketones, acetate esters, carbitols, aromatic hydrocarbons, dimethylformamide, dimethylacetamide, or N-methylpyrrolidone are preferred, with the amount used being 30 to 60% by mass based on nonvolatile content.

A curing accelerator or catalyst can be used in the resin composition of the present invention, if necessary. Examples of curing accelerators or catalysts include imidazoles, tertiary amines, phosphorus compounds such as phosphines, metal compounds, Lewis acids, and amine complex salts. These may be used alone or in combination of two or more types.

The amount of curing accelerator or catalyst used can be selected appropriately depending on the intended use, but 0.01 to 15 parts by mass is used as needed per 100 parts by mass of the epoxy resin component in the resin composition. Preferably, it is 0.01 to 10 parts by mass, more preferably 0.05 to 8 parts by mass, even more preferably 0.1 to 5 parts by mass, and especially preferably 0.1 to 1.0 part by mass. Using a curing accelerator or catalyst can lower the curing temperature and shorten the curing time.

In order to improve the flame retardancy of the resulting cured product, various known flame retardants can be used in the resin composition of the present invention, as long as reliability is not reduced. Usable flame retardants include, for example, halogen-based flame retardants, phosphorus-based flame retardants, nitrogen-based flame retardants, silicone-based flame retardants, inorganic flame retardants, and organic metal salt-based flame retardants. From an environmental perspective, halogen-free flame retardants are preferred, and phosphorus-based flame retardants are particularly preferred. These flame retardants may be used alone, or two or more types of the same type may be used in combination, or different types of flame retardants may be used in combination.

The resin composition of the present invention may contain components other than those listed above (sometimes referred to as "other components" in the present invention) in order to further improve its functionality. Such other components include fillers, thermoplastic resins, thermosetting resins, photocurable resins, UV inhibitors, antioxidants, coupling agents, plasticizers, fluxes, thixotropic agents, smoothing agents, colorants, pigments, dispersants, emulsifiers, elasticity reducing agents, release agents, antifoaming agents, ion trapping agents, etc.

Examples of fillers include inorganic fillers such as fused silica, crystalline silica, alumina, silicon nitride, boron nitride, aluminum nitride, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, boehmite, talc, mica, clay, calcium carbonate, magnesium carbonate, barium carbonate, zinc oxide, titanium oxide, magnesium oxide, magnesium silicate, calcium silicate, zirconium silicate, barium sulfate, and carbon; fibrous fillers such as carbon fiber, glass fiber, alumina fiber, silica-alumina fiber, silicon carbide fiber, polyester fiber, cellulose fiber, aramid fiber, and ceramic fiber; and fine particle rubber.

The resin composition of the present invention may be used in combination with a thermoplastic resin other than the modified epoxy resin of the present invention. Examples of thermoplastic resins include modified epoxy resins other than those of the present invention, phenoxy resins, polyurethane resins, polyester resins, polyethylene resins, polypropylene resins, polystyrene resins, ABS resins, AS resins, vinyl chloride resins, polyvinyl acetate resins, polymethyl methacrylate resins, polycarbonate resins, polyacetal resins, cyclic polyolefin resins, polyamide resins, thermoplastic polyimide resins, polyamideimide resins, polytetrafluoroethylene resins, polyetherimide resins, polyphenylene ether resins, modified polyphenylene ether resins, polyethersulfone resins, polysulfone resins, polyetheretherketone resins, polyphenylene sulfide resins, and polyvinyl formal resins. Modified epoxy resins and phenoxy resins other than those of the present invention are preferred in terms of compatibility, while polyphenylene ether resins and modified polyphenylene ether resins are preferred in terms of low dielectric properties.

Other components include organic pigments such as quinacridone, azo, and phthalocyanine pigments; inorganic pigments such as titanium oxide, metal foil pigments, and anti-rust pigments; UV absorbers such as hindered amines, benzotriazoles, and benzophenones; antioxidants such as hindered phenols, phosphorus, sulfur, and hydrazides; release agents such as stearic acid, palmitic acid, zinc stearate, and calcium stearate; and additives such as leveling agents, rheology control agents, pigment dispersants, anti-cracking agents, and defoamers. The amount of these other components added is preferably 0.01 to 20% by mass of the total solids content of the resin composition.

The resin composition of the present invention is obtained by uniformly mixing the above components. Resin compositions containing modified epoxy resins, curing agents, and other optional components can be easily cured using methods similar to those known in the art. These cured products exhibit excellent curing properties, with an excellent balance of low moisture absorption, dielectric properties, heat resistance, and adhesion. "Curing" here refers to intentionally curing the resin composition using heat and/or light, and the degree of curing can be controlled depending on the desired properties and application. The degree of curing can be fully cured or partially cured, and is not particularly limited; however, the reaction rate of the curing reaction between the epoxy groups and the curing agent is typically 5 to 95%.

The resin composition of the present invention can be cured to produce a cured product by methods similar to those used for known epoxy resin compositions. Suitable methods for obtaining a cured product include casting, injection, potting, dipping, drip coating, transfer molding, compression molding, etc., or laminating the resin into a resin sheet, resin-coated copper foil, prepreg, etc., and curing under heat and pressure to produce a laminate. The curing temperature is typically in the range of 80-300°C, and the curing time is typically approximately 10-360 minutes. This heating is preferably performed in two stages: a primary heating at 80-180°C for 10-90 minutes, followed by a secondary heating at 120-200°C for 60-150 minutes. For formulations whose glass transition temperature (Tg) exceeds the secondary heating temperature, a tertiary heating at 150-280°C for 60-120 minutes is also preferred. Performing these secondary and tertiary heating stages can reduce poor curing. When producing semi-cured resin products such as resin sheets, resin-coated copper foils, and prepregs, the curing reaction of the resin composition is typically allowed to proceed to an extent that the shape can be maintained by heating or other methods. If the resin composition contains a solvent, most of the solvent is typically removed by methods such as heating, reducing pressure, or air drying, although up to 5% by mass of the solvent may remain in the semi-cured resin product.

The following describes a prepreg obtained using the resin composition of the present invention. The sheet-like substrate can be, but is not limited to, a woven or nonwoven fabric made from inorganic fibers such as glass, or organic fibers such as polyester, polyamine, polyacrylic, polyimide, Kevlar, or cellulose. The method for producing a prepreg from the resin composition and substrate of the present invention is not particularly limited. For example, the substrate can be immersed in a resin varnish in which the viscosity of the resin composition is adjusted with a solvent, and then heated and dried to semi-cure (B-stage) the resin component. For example, the prepreg can be obtained by heating and drying at 100 to 200°C for 1 to 40 minutes. The resin content in the prepreg is preferably 30 to 80% by mass.

This section describes a method for manufacturing a laminate using prepregs and insulating adhesive sheets. When forming a laminate using prepregs, one or more prepregs are laminated together, with metal foil placed on one or both sides to form a laminate. This laminate is then heated and pressurized to form an integrated laminate. The metal foil can be a single, alloy, or composite metal foil of copper, aluminum, brass, nickel, or the like. The conditions for heating and pressing the laminate can be appropriately adjusted to cure the resin composition. However, if the pressure is too low, air bubbles may remain inside the resulting laminate, resulting in reduced electrical properties. Therefore, it is desirable to pressurize the laminate under conditions that satisfy moldability. For example, the temperature can be set to 160 to 220°C, the pressure to 49 to 490 N/cm ² (5 to 50 kgf/cm ² ), and the heating time to 40 to 240 minutes.

The single-layer laminate obtained in this way can then be used as an inner layer material to create a multilayer board. In this case, a circuit is first formed on the laminate using an additive or subtractive method, and the surface of the formed circuit is then treated with an acid solution for blackening to obtain the inner layer material. An insulating layer is then formed using a prepreg or insulating adhesive sheet on one or both circuit-forming surfaces of this inner layer material, and a conductor layer is then formed on the surface of the insulating layer to form the multilayer board.

When forming an insulating layer using an insulating adhesive sheet, a laminate is formed by placing an insulating adhesive sheet on the circuit-forming surfaces of multiple inner layer materials. Alternatively, a laminate is formed by placing an insulating adhesive sheet between the circuit-forming surfaces of the inner layer materials and metal foil. This laminate is then heated and pressurized to form an integral molding, thereby forming the cured insulating adhesive sheet as an insulating layer and forming a multilayer inner layer material. Alternatively, the inner layer material and the metal foil serving as the conductor layer are combined to form the cured insulating adhesive sheet as an insulating layer. Here, the metal foil can be the same as that used in the laminate used as the inner layer material.
Furthermore, the hot and pressure molding can be carried out under the same conditions as those for molding the inner layer material. When forming an insulating layer by applying a resin composition to a laminate, the resin on the circuit-forming surface of the outermost layer of the inner layer material is preferably applied to a thickness of 5 to 100 μm with the above-mentioned resin composition, and then heated and dried at 100 to 200°C for 1 to 90 minutes to form a sheet. This is generally formed by a method known as a casting method. The thickness after drying is preferably formed to 5 to 80 μm. A printed wiring board can be formed by further forming via holes and circuits on the surface of the multilayer laminate formed in this way using an additive method or a subtractive method.
Furthermore, by repeating the above process using this printed wiring board as an inner layer material, it is possible to form a multi-layer laminate.

When forming an insulating layer using prepreg, one or more prepreg sheets are placed on the circuit-forming surface of the inner layer material, and a metal foil is placed on the outside of the prepreg to form a laminate. This laminate is then heated and pressurized to form an integral molding, whereby the cured prepreg is formed as an insulating layer and the outer metal foil is formed as a conductor layer.
Here, the metal foil may be the same as that used in the laminate used as the inner layer material. The hot-press molding can be carried out under the same conditions as those for molding the inner layer material. The surface of the multilayer laminate thus molded can be further subjected to via hole formation and circuit formation by an additive method or a subtractive method to mold a printed wiring board.
Furthermore, by repeating the above process using this printed wiring board as an inner layer material, it is possible to form a multi-layer board with even more layers.

The cured products and laminates for electrical and electronic circuits obtained from the resin composition of the present invention have excellent dielectric properties and heat resistance.

The present invention will be explained in more detail below based on examples and comparative examples, but the present invention is not limited to these. Unless otherwise specified, parts represent "parts by mass" and % represents "% by mass." Analytical and measurement methods are shown below. Furthermore, the unit of all equivalents is "g/eq."

(1) Weight average molecular weight (Mw) and number average molecular weight (Mn):
It was determined by GPC measurement. Specifically, a main body HLC8320GPC (manufactured by Tosoh Corporation) equipped with columns (TSKgel SuperH-H, SuperH2000, SuperHM-H, SuperHM-H, all manufactured by Tosoh Corporation) in series was used, and the column temperature was set to 40°C. The eluent was tetrahydrofuran (THF) at a flow rate of 1.0 mL/min, and a differential refractive index detector was used as the detector. 0.1 g of the solid content was dissolved in 10 mL of THF, and 50 μL of the solution was filtered through a 0.45 μm microfilter. Data processing was performed using GPC8020 Model II Version 6.00 manufactured by Tosoh Corporation.

(2) IR (infrared absorption spectrum):
A Fourier transform infrared spectrophotometer (Spectrum One FT-IR Spectrometer 1760X, manufactured by Perkin Elmer Precisly) was used, and sodium chloride was used as a cell. A sample dissolved in chloroform was applied to the cell, dried, and then the transmittance at wave numbers of 400 to 4000 ^cm was measured.

(3) Epoxy equivalent:
Measurements were carried out in accordance with JIS K 7236. Specifically, a potentiometric titrator was used, cyclohexanone was used as the solvent, tetraethylammonium bromide acetate solution was added, and a 0.1 mol/L perchloric acid-acetic acid solution was used. For the solvent-diluted product (resin varnish), the solid content was calculated from the nonvolatile content.

(4) Nonvolatile content:
Measurement was carried out in accordance with JIS K 7235. The drying temperature was 200°C and the drying time was 60 minutes.

(5) Solvent solubility:
The modified epoxy resin was dissolved in methyl ethyl ketone (MEK) to prepare a resin varnish with a resin content of 40%, which was then kept in a thermostatic chamber at 25° C. for 24 hours, after which the state was visually judged.
Transparent: ○, Cloudy: △, Separation: ×

(6) Resin compatibility:
The modified epoxy resin was mixed with A1, a bisphenol A liquid epoxy resin, under heat, and the mixture was kept in a thermostatic chamber at 25°C for 24 hours, after which the state was visually evaluated. The mixture was mixed in a ratio of modified epoxy resin/A1 = 50/50 (mass ratio).
Transparent: ○, Cloudy: △, Separation: ×

(7) Glass transition temperature (Tg):
Measurement was performed in accordance with the IPC-TM-650 2.4.25.c standard. Specifically, a sample having a thickness of 4 mm and a diameter of 3 mm was subjected to two cycles of measurement in the range of 20 to 280°C at a temperature increase rate of 10°C/min using a differential scanning calorimeter EXSTAR6000 DSC6200 (manufactured by SII NanoTechnology Inc.), and the glass transition temperature (Tmg) was expressed as the midpoint of the measurement chart obtained from the second scan.

(8) Dielectric properties:
The film-shaped sample was measured using the cavity resonator perturbation method, and the plate-shaped sample was measured using the capacitance method.
The dielectric loss tangents of Examples 14 to 19 and Comparative Examples 4 and 5 were evaluated by measuring at 1 GHz using a cavity resonator perturbation method. Specifically, the measurements were performed using a PNA network analyzer N5230A (manufactured by Agilent Technologies Inc.) and a cavity resonator CP431 (manufactured by Kanto Electronics Application Development Co., Ltd.) in a measurement environment of room temperature 23°C and humidity 50% RH, using test pieces with a width of 1.5 mm, a length of 80 mm, and a thickness of 150 μm.
The dielectric loss tangents of Examples 20 and 21 and Comparative Examples 6 and 7 were evaluated by a capacitance method at 1 GHz. Specifically, the measurements were performed using a Material Analyzer (manufactured by Agilent Technologies) in accordance with the IPC-TM-650 2.5.5.9 standard, under a measurement environment of room temperature of 23°C and humidity of 50% RH, using test pieces of 30 mm square and 1 mm thick.

(9) Film formability:
A film was prepared from the modified epoxy resin and a cured product thereof, and the obtained film was bent 180 degrees and evaluated based on the number of times it could be bent.
10 or more times: ○, 1 to 9 times: △, 0 times: ×

The abbreviations used in the examples and comparative examples are as follows:

[Bifunctional epoxy resin]
A1: Bisphenol A liquid epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd., YD-128, epoxy equivalent 186, m≒0.11)
A2: Fluorene-type epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd., ESF-300, epoxy equivalent 250, softening point 87°C, m≒0.09)
A3: Biphenyl-type epoxy resin (manufactured by Mitsubishi Chemical Corporation, YX-4000, epoxy equivalent 196, melting point 105°C, m≒0.13)
A4: Naphthalene-type liquid epoxy resin (manufactured by DIC Corporation, Epicron HP4032D, epoxy equivalent 142, m≒0.06)
A5: Bisphenol A solid epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd., YD-901, epoxy equivalent 410, m≒1.7)
A6: Bisphenol A solid epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd., YD-7910, epoxy equivalent 2500, m≒16)
Here, m has the same meaning as m in the above formula (3).

[Diester compounds]
B1: Diacetoxyphenolphthalein (active equivalent = 201) obtained in Synthesis Example 1
B2: Diacetoxyphenolphthalein anilide (active equivalent = 261) obtained in Synthesis Example 2
B3: 4,4'-diacetoxybiphenyl (Tokyo Chemical Industry Co., Ltd., active equivalent weight = 135)

[Bifunctional phenolic compounds]
C1: Phenolphthalein (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., hydroxyl equivalent: 159)
C2: Phenolphthalein anilide (manufactured by Yamanishi Ryusei Pharmaceutical Co., Ltd., hydroxyl equivalent: 219)
C3: 4,4'-dihydroxybiphenyl (Tokyo Chemical Industry Co., Ltd., hydroxyl equivalent: 93)

[catalyst]
D1: N,N'-dimethylaminopyridine (Tokyo Chemical Industry Co., Ltd.)
D2: 2-ethyl-4-methylimidazole (Curesol 2E4MZ, manufactured by Shikoku Chemicals Corporation)

[Solvents]
S1: Cyclohexanone S2: Methyl ethyl ketone (MEK)

[Acid anhydride]
E1: Acetic anhydride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
E2: Benzoic anhydride (Tokyo Chemical Industry Co., Ltd.)

[Curing agent]
H1: Phenol novolak resin (manufactured by Aica Kogyo Co., Ltd., Shounol BRG-557, hydroxyl group equivalent: 105)

Synthesis Example 1
A glass reaction vessel equipped with a stirrer, a thermometer, a nitrogen gas inlet, a condenser, and a dropping device was charged with 100 parts of bifunctional phenol compound C1, 64 parts of acid anhydride E1, and 50 parts of pyridine at room temperature, and the mixture was heated to 60°C while stirring under nitrogen gas flow, and reacted for 2 hours. Thereafter, the mixture was dried under reduced pressure at 150°C and 1.3 kPa (10 torr) for 2 hours, yielding 126 parts of diester compound B1.

Synthesis Example 2
A glass reaction vessel equipped with a stirrer, a thermometer, a nitrogen gas inlet, a condenser, and a dropping device was charged with 100 parts of bifunctional phenol compound C2, 47 parts of acid anhydride E1, and 36 parts of pyridine at room temperature, and the mixture was heated to 60°C while stirring under nitrogen gas flow, and reacted for 2 hours. Thereafter, the mixture was dried under reduced pressure at 150°C and 1.3 kPa (10 torr) for 2 hours, yielding 119 parts of diester compound B2.

Example 1
A glass reaction vessel equipped with a stirrer, thermometer, nitrogen gas inlet, condenser, and dropping device was charged with 100 parts of bifunctional epoxy resin A1, 103 parts of diester compound B1, and 51 parts of reaction solvent S1 at room temperature, and the mixture was heated to 130°C while stirring under a nitrogen gas stream. 0.2 parts of catalyst D1 was added, and the mixture was then heated to 145°C and reacted at that temperature for 7 hours. Dilution and mixing was performed using 51 parts of dilution solvent S1 and 203 parts of dilution solvent S2 to obtain a modified epoxy resin resin varnish (R1) with a nonvolatile content of 40%.

Examples 2 to 11, Comparative Examples 1 to 3
Resin varnishes were obtained in the same manner as in Example 1, using the amounts (parts) of each raw material shown in Table 1. The "molar ratio" in the table indicates the molar ratio of the difunctional epoxy resin to the diester compound and the difunctional phenol compound.

Example 12
100 parts (40 parts solids) of the resin varnish (HR3) obtained in Comparative Example 3 and 600 parts of reaction solvent S1 were blended, and after heating to 100°C, 5 parts of acid anhydride E1 were added and reacted for 4 hours. The resulting resin varnish was added to methanol, and the precipitated insoluble matter was filtered off. The filtrate was then dried in a vacuum dryer at 150°C and 0.4 kPa (3 torr) for 1 hour to obtain a modified epoxy resin. 20 parts of dilution solvent S1 and 41 parts of dilution solvent S2 were added to the resulting modified epoxy resin, and the mixture was dissolved uniformly to obtain a resin varnish (R12) with a nonvolatile content of 40%.

Example 13
A resin varnish (R13) was obtained in the same manner as in Example 11, except that the amount of acid anhydride E1 was 24 parts, the amount of dilution solvent S1 was 22 parts, and the amount of dilution solvent S2 was 44 parts.

Example 14
A resin varnish (R14) was obtained in the same manner as in Example 11, except that 52 parts of E2 were used instead of E1, 25 parts of diluent S1, and 52 parts of S2 were used.

The resin varnishes R1 to R14 and HR1 to HR3 obtained in Examples 1 to 14 and Comparative Examples 1 to 3 were applied to an iron plate so that the film thickness after drying would be 100 μm, and then dried using a dryer at 150° C. for 1 hour to obtain a resin film.
The epoxy equivalent and Mw of the resin varnish were measured, and the solvent solubility, resin compatibility, and film-forming ability (excluding low-molecular-weight epoxies) of the resin film were measured. The results are shown in Table 2. In the table, "acylation rate" represents the content (mol %) of acyl groups in all Z, "formula (2) rate" represents the content (mol %) of divalent groups represented by formula (2) in all X, and "-" represents not measured. The examples using resin varnishes HR1 to HR3 are comparative examples.

Examples 15 to 20, Comparative Examples 4 and 5
A resin composition was prepared by blending 30 parts (12 parts solids) of the modified epoxy resin varnishes (R1-R5, R13, HR1-HR2) obtained in Examples 1-5 and 13 and Comparative Examples 1-2 with 2 parts of another epoxy resin A1, 2.5 parts of a 50% MEK solution of curing agent H1, and 0.6 parts of a 20% MEK solution of curing accelerator D2. These compositions were then applied to steel plates to dry to thicknesses of 100 μm and 150 μm, and dried in a dryer at 150°C for 1 hour to obtain cured polymer films. The Tg, dielectric loss tangent, and film-forming properties were measured. The results are shown in Table 3.

Example 21
250 parts (100 parts solids) of modified epoxy resin varnish R8, 25.6 parts of curing agent H1, and 0.3 parts of curing accelerator D2 were blended and dissolved in a mixed solvent prepared with MEK, propylene glycol monomethyl ether, and N,N-dimethylformamide to obtain a resin composition varnish. The obtained resin composition varnish was impregnated into glass cloth (manufactured by Nitto Boseki Co., Ltd., WEA 7628 XS13, 0.18 mm thick). The impregnated glass cloth was dried for 9 minutes in a hot air circulating oven at 150°C to obtain a prepreg.

The obtained prepreg was loosened and sieved to obtain prepreg powder, passing through a 100-mesh sieve. The obtained prepreg powder was placed in a fluororesin mold and vacuum pressed at 2 MPa under temperature conditions of 130°C for 15 minutes and 190°C for 80 minutes to obtain test specimens measuring 30 mm square and 1 mm thick. The Tg and dielectric tangent of the test specimens are shown in Table 4.

Example 22, Comparative Examples 6 and 7
The components were blended in the amounts (parts) shown in Table 4, and the same operations as in Example 21 were carried out to obtain a resin composition varnish, a prepreg, and a test piece. The same tests as in Example 21 were carried out, and the results are shown in Table 4.

As can be seen from Table 2, the modified epoxy resin of the present invention is excellent in dielectric properties and heat resistance. Furthermore, as can be seen from Tables 3 and 4, the cured product made from the resin composition of the present invention is also excellent in dielectric properties and heat resistance.

Claims (10)

A modified epoxy resin represented by the following formula (1) and having an epoxy equivalent of 400 to 100,000 g/eq.
(In the formula, X is a divalent group and has at least a divalent group represented by the above formula (2). Y is independently a hydrogen atom, an acyl group having 2 to 20 carbon atoms, or a glycidyl group. Z is an acyl group having 2 to 20 carbon atoms or a hydrogen atom, and 5 mol % or more of the acyl group is the above. n is the average number of repetitions and is 1 or more and 500 or less. A is an arylene group, R ¹ is selected from —O— or —N(Ph)— (Ph: phenyl group), and R ² is —CO— or —SO ₂ —. ) A resin composition comprising the modified epoxy resin of claim 1 and a curing agent. The resin composition according to claim 2, comprising 0.1 to 100 parts by mass of the curing agent as solids per 100 parts by mass of the epoxy resin solids. The resin composition according to claim 2 or 3, comprising the modified epoxy resin according to claim 1, another epoxy resin, and a curing agent, wherein the mass ratio of the solid content of the modified epoxy resin to the other epoxy resin is 99/1 to 1/99. The resin composition according to claim 4, which contains 0.1 to 100 parts by mass of the curing agent as solids per 100 parts by mass of the total solids of the modified epoxy resin and the other epoxy resin. The resin composition according to any one of claims 2 to 5, wherein the curing agent is at least one selected from the group consisting of acrylic ester resins, melamine resins, urea resins, phenolic resins, acid anhydride compounds, amine compounds, imidazole compounds, amide compounds, cationic polymerization initiators, organic phosphines, polyisocyanate compounds, blocked isocyanate compounds, carbodiimide compounds, and active ester curing agents. A cured product obtained by curing the resin composition described in any one of claims 2 to 6. A laminate for electrical and electronic circuits made using the resin composition described in any one of claims 2 to 6. A method for producing a modified epoxy resin, comprising reacting a bifunctional epoxy resin represented by the following formula (3) with a compound represented by the following formula (4) to obtain a modified epoxy resin represented by the following formula (1) having an epoxy equivalent of 400 to 100,000 g/eq.:
(wherein X ¹ and X ² are divalent groups, and X ¹ and/or X ² contain a divalent group represented by the above formula (2). X is a divalent group and has at least the divalent group represented by the above formula (2). G is a glycidyl group, and Y is independently a hydrogen atom, an acyl group having 2 to 20 carbon atoms, or a glycidyl group. Z is an acyl group having 2 to 20 carbon atoms or a hydrogen atom, and 5 mol % or more of Z is the above acyl group. Q is an acyl group having 2 to 20 carbon atoms or a hydrogen atom, and 5 mol % or more of Z is the above acyl group. Here, the compound represented by formula (4) may be a mixture of two or more selected from compounds in which both Qs are acyl groups, compounds in which one Q is an acyl group, and compounds in which both Qs are hydrogen atoms. m is the average number of repetitions and is 0 to 6. n is the average number of repetitions and is 1 to 500. A is an arylene group, ^{R 1} is selected from —O— or —N(Ph)— (Ph: phenyl group), and R ² is —CO— or —SO ₂ —. A method for producing a modified epoxy resin, comprising reacting 0.05 mol to 2.0 mol of an acid anhydride represented by the following formula (6) with 1 mol of an alcoholic hydroxyl group equivalent of an epoxy resin represented by the following formula (5), to obtain a modified epoxy resin represented by the following formula (1) having an epoxy equivalent of 400 to 100,000 g/eq.
(In the formula, X is a divalent group and includes a divalent group represented by the above formula (2). L is independently a hydrogen atom or a glycidyl group. Y is independently a hydrogen atom, an acyl group having 2 to 20 carbon atoms, or a glycidyl group. Z is an acyl group having 2 to 20 carbon atoms or a hydrogen atom, and 5 mol % or more of Z are the above acyl groups. T is an acyl group having 2 to 20 carbon atoms. n is the average number of repetitions and is 1 or more and 500 or less. A is an arylene group, R ¹ is selected from —O— or —N(Ph)— (Ph: phenyl group), and R ² is —CO— or —SO ₂ —. )