JP7733730B2 - Phosphorus-containing modified epoxy resin, resin composition, cured product, laminate for electric/electronic circuits, and method for producing phosphorus-containing modified epoxy resin - Google Patents

Description

The present invention relates to a phosphorus-containing modified epoxy resin that has excellent flame retardancy and solvent solubility. It also relates to a resin composition containing the phosphorus-containing modified epoxy resin and a curing agent, a cured product thereof that has excellent flame retardancy, and a laminate for electrical and electronic circuits made from the 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, those containing phosphorus or bromine atoms in their skeletons are used as flame retardants blended into epoxy resin compositions and thermoplastic resins.

Epoxy resins used in electrical materials such as laminates for electrical and electronic circuits require flame retardancy and solvent solubility.

Halogen-free flame-retardant technology using phosphorus compounds has been investigated for making epoxy resins flame-retardant. Patent Documents 1 to 3 disclose phosphorus-containing flame-retardant epoxy resins obtained by reacting specific phosphorus compounds with epoxy resins. Specifically, Patent Documents 1 and 2 disclose phosphorus-containing flame-retardant epoxy resins obtained by reacting 10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide with an epoxy resin in a predetermined molar ratio. Patent Document 3 also discloses a phosphorus-containing flame-retardant epoxy resin obtained by reacting 10-(2,7-dihydroxynaphthyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide with an epoxy resin in a predetermined ratio. However, the phosphorus-containing flame-retardant epoxy resins obtained by these methods have poor solubility in epoxy resins and solvents.

Japanese Patent Application Publication No. 04-11662 Japanese Patent Application Laid-Open No. 2000-309623 Japanese Patent Application Publication No. 11-279258

The objective of the present invention is to provide a phosphorus-containing modified epoxy resin that has excellent flame retardancy and solubility. It is also an object of the present invention to provide a cured product that has excellent flame retardancy by curing a resin composition containing the same.

In order to solve the above problems, the inventors conducted extensive research into phosphorus-containing modified epoxy resins and discovered that phosphorus-containing modified epoxy resins with a specific structure have excellent flame retardancy and solubility, and further discovered that cured products obtained by curing resin compositions containing such resins have excellent flame retardancy, thereby completing the present invention.

That is, the present invention relates to a phosphorus-containing modified epoxy resin represented by the following formula (1), having an epoxy equivalent of 300 g/eq. or more and less than 5,000 g/eq., and a phosphorus content of 1.0 to 6.0 mass%.
During the ceremony,
X is independently a divalent group and has at least a phosphorus-containing divalent group represented by the following 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 is an acyl group.
n is the average number of repetitions, and is greater than 0 and less than or equal to 30.

During the ceremony,
A is a trivalent aromatic hydrocarbon group having 6 to 20 carbon atoms.
^R1 and ^R2 are each independently a hydrocarbon group having 1 to 20 carbon atoms which may contain a heteroatom, and may be linear, branched, or cyclic, or ^R1 and ^R2 may be bonded to form a cyclic structure.
k1 and k2 each independently represent 0 or 1.

The number average molecular weight (Mn) of the above phosphorus-containing modified epoxy resin is preferably 500 to 10,000.

The present invention also provides a resin composition containing the above phosphorus-containing modified epoxy resin and a curing agent.
The resin composition preferably contains 1 to 100 parts by mass of a curing agent per 100 parts by mass of the phosphorus-containing modified epoxy resin.

The resin composition contains the phosphorus-containing modified epoxy resin, an epoxy resin, and a curing agent, and the mass ratio of the phosphorus-containing modified epoxy resin to the epoxy resin can be 99/1 to 1/99.
This resin composition preferably contains 1 to 100 parts by mass of a curing agent per 100 parts by mass of the total of the phosphorus-containing modified epoxy resin and the epoxy resin.

The curing agent to be incorporated 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 anhydrides, 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 resin composition.
The present invention further relates to a laminate for use in electric/electronic circuits, which is made using the above resin composition.

The present invention also provides a method for producing a phosphorus-containing modified epoxy resin, which comprises reacting a bifunctional epoxy resin represented by the following formula (4) with a compound represented by the following formula (5) to obtain the phosphorus-containing modified epoxy resin:
where:
X ¹ and X ² are independently divalent groups, and one or both of X ¹ and X ² contains at least a phosphorus-containing divalent group represented by the above formula (2).
G is a glycidyl group.
Q is independently an acyl group having 2 to 20 carbon atoms or a hydrogen atom, and 5 mol % or more of Q is an acyl group.
m is the average number of repetitions, and is 0 to 6 inclusive.
Here, the compound represented by formula (5) may be a compound in which at least one Q is an acyl group, or a mixture of a compound in which at least one Q is an acyl group and a compound in which both Qs are hydrogen atoms.

The present invention provides a phosphorus-containing modified epoxy resin with excellent flame retardancy and solubility. Furthermore, a resin composition using this phosphorus-containing modified epoxy resin can provide a cured product with excellent flame retardancy and strength.

1 is a GPC chart of the phosphorus-containing modified epoxy resin of Example 1. 1 is an IR chart of the phosphorus-containing modified epoxy resin of Example 1. 1 is a GPC chart of the phosphorus-containing modified epoxy resin of Example 6. 1 is an IR chart of the phosphorus-containing modified epoxy resin of Example 6. 1 is a GPC chart of the phosphorus-containing modified epoxy resin of Example 7. 1 is an IR chart of the phosphorus-containing modified epoxy resin of Example 7.

The phosphorus-containing modified epoxy resin of the present invention has an epoxy equivalent of 300 g/eq. or more and less than 5,000 g/eq. represented by general formula (1), a phosphorus content of 1 to 6 mass%, and a phosphorus-containing structure represented by formula (2) above, in which some or all of the hydrogen atoms in the secondary hydroxyl groups have been substituted with acyl groups (Z).

The phosphorus-containing modified epoxy resin of the present invention has a structure in which the hydrogen atoms in the secondary hydroxyl groups are replaced with acyl groups, making it less polar and more soluble.

In general formula (1), X is independently a divalent group containing a phosphorus-containing structure represented by formula (2), i.e., a group consisting of the structure represented by formula (2) or this structure and another divalent group other than this.
X is independently either a structure represented by formula (2) or a divalent group other than this, but at least includes a structure represented by formula (2). Examples of the divalent group other than the structure represented by formula (2) include a residue in which two hydroxyl groups have been removed from a bifunctional phenol compound that may be used in combination as a raw material, which will be described later.
The number of moles of X in the structure represented by formula (2) in total is determined depending on the structure of the phosphorus-containing group represented by formula (3) below and the desired phosphorus content.
In the formula, R ¹ , R ² , k1 and k2 each have the same meaning as in formula (2).

The structure represented by formula (2) is a residue obtained by removing two hydroxyl groups from a phosphorus-containing bifunctional phenol compound (p1) described below. This phosphorus-containing bifunctional phenol compound (p1) is obtained by reacting an organic phosphorus compound (p2) with a quinone compound.

In formula (2), A is a trivalent aromatic hydrocarbon group having 6 to 20 carbon atoms derived from a quinone compound. Examples of aromatic hydrocarbon groups include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, and a benzene ring group or a naphthalene ring group is preferred.

In formula (2), the aromatic hydrocarbon group A may have as a substituent an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or an aralkyloxy group having 7 to 12 carbon atoms.

For example, examples of alkyl groups having 1 to 8 carbon atoms include methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl, and hexyl groups; examples of cycloalkyl groups having 5 to 8 carbon atoms include cyclohexyl groups; examples of aryl or aryloxy groups having 6 to 10 carbon atoms include phenyl, naphthyl, phenoxy, and naphthyloxy groups; and examples of aralkyl or aralkyloxy groups having 7 to 11 carbon atoms include benzyl, phenethyl, 1-phenylethyl, benzyloxy, and naphthylmethyloxy groups.

Preferred A is a benzene ring, a methyl-substituted benzene ring, a 1-phenylethyl-substituted benzene ring, a naphthalene ring, a methyl-substituted naphthalene ring, or a 1-phenylethyl-substituted naphthalene ring. For applications requiring greater solubility, a benzene ring, a methyl-substituted benzene ring, or a 1-phenylethyl-substituted benzene ring is preferred, while for applications requiring greater flame retardancy and heat resistance, a naphthalene ring, a methyl-substituted naphthalene ring, or a 1-phenylethyl-substituted naphthalene ring is preferred.

In formula (2), the phosphorus-containing group represented by formula (3) is a residue of an organic phosphorus compound (p2) described below. ^R1 and ^R2 are hydrocarbon groups having 1 to 20 carbon atoms which may contain a heteroatom, and may be different or the same, and may be linear, branched, or cyclic. ^R1 and ^R2 may also be bonded to form a cyclic structure.
Examples of hydrocarbon groups having 1 to 20 carbon atoms include alkyl groups having 1 to 12 carbon atoms, alkoxy groups having 1 to 8 carbon atoms, aryl groups having 6 to 12 carbon atoms, alkynyl groups having 2 to 12 carbon atoms, aryloxy groups having 6 to 10 carbon atoms, and aralkyloxy groups having 7 to 11 carbon atoms, and aryl groups such as a benzene ring are particularly preferred.

Examples of alkyl groups having 1 to 12 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, neopentyl, t-pentyl, cyclopentyl, n-hexyl, isohexyl, cyclohexyl, n-heptyl, cycloheptyl, methylcyclohexyl, n-octyl, cyclooctyl, n-nonyl, 3,3,5-trimethylcyclohexyl, n-decyl, cyclodecyl, n-undecyl, n-dodecyl, cyclododecyl, benzyl, methylbenzyl, dimethylbenzyl, trimethylbenzyl, naphthylmethyl, phenethyl, and 2-phenylisopropyl.

Examples of alkoxy groups having 1 to 8 carbon atoms include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, t-butoxy, n-pentoxy, isopentoxy, neopentoxy, t-pentoxy, cyclopentoxy, n-hexyloxy, isohexyloxy, cyclohexyloxy, n-heptoxy, cycloheptoxy, methylcyclohexyloxy, Examples of such an alkyl group include an n-octyloxy group, a cyclooctyloxy group, an n-nonyloxy group, a 3,3,5-trimethylcyclohexyloxy group, an n-decyloxy group, a cyclodecyloxy group, an n-undecyloxy group, an n-dodecyloxy group, a cyclododecyloxy group, a benzyloxy group, a methylbenzyloxy group, a dimethylbenzyloxy group, a trimethylbenzyloxy group, a naphthylmethoxy group, a phenethyloxy group, and a 2-phenylisopropoxy group.

Examples of aryl groups having 6 to 12 carbon atoms include phenyl, o-tolyl, m-tolyl, p-tolyl, ethylphenyl, styryl, xylyl, n-propylphenyl, isopropylphenyl, mesityl, ethynylphenyl, naphthyl, and vinylnaphthyl groups.

Examples of alkynyl groups having 2 to 12 carbon atoms include ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3-butynyl, 1,3-butadienyl, phenylethynyl, and naphthylethynyl groups.

When ^R1 and ^R2 are aryl groups, they may have as a substituent an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aralkyl group having 7 to 11 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, or an aralkyloxy group having 7 to 11 carbon atoms. Examples of heteroatoms include oxygen atoms, which can be contained between carbon atoms constituting the hydrocarbon chain or hydrocarbon ring.

The phosphorus-containing group is preferably a phosphorus-containing group represented by the following formula (3a) or (3b).
In the formula, ^R3 and ^R4 each independently represent a hydrogen atom or a hydrocarbon group having 1 to 11 carbon atoms, and specifically represent a hydrogen atom, a methyl group, an ethyl group, a t-butyl group, a cyclohexyl group, a phenyl group, a tolyl group, a benzyl group, or the like. Of these , a hydrogen atom, a methyl group, a cyclohexyl group, a phenyl group, a tolyl group, or a benzyl group is preferred, and a hydrogen atom, a methyl group, a phenyl group, or a benzyl group is more preferred.

Examples of phosphorus-containing groups other than the phosphorus-containing group represented by formula (3a) or formula (3b) include, but are not limited to, phosphorus-containing groups represented by the following formulas (a1) to (a10).

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, so it is advisable to control the ratio 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 the aralkyl group having 7 to 13 carbon atoms include a benzyl group, a methylbenzyl group, a dimethylbenzyl group, a trimethylbenzyl group, a phenethyl group, a 2-phenylisopropyl group, and a naphthylmethyl group.
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 (hereinafter, sometimes simply referred to as an "acyl group") or a hydrogen atom. 5 mol % or more of Z are acyl groups, and the remainder are hydrogen atoms. The content (mol %) of acyl groups in all Z in formula (1) is also referred to as the acylation rate.
The acylation rate is preferably 10 mol% or more, more preferably 50 mol% or more, and even more preferably 70 mol% or more. On the other hand, there is no upper limit to the acylation rate, and it may be 100 mol%, but in terms of reactivity, it is about 95%.
When all Z's (100 mol%) are acyl groups, the phosphorus-containing modified epoxy resin of the present invention does not contain secondary hydroxyl groups, and solubility can be further improved. Improvements in dielectric properties and moisture resistance can also be expected. On the other hand, for example, when fine-tuning adhesion to metals, a portion of Z's can be left as hydrogen atoms, allowing an appropriate amount of secondary hydroxyl groups to be intentionally present in the phosphorus-containing modified epoxy resin of the present invention, as long as this does not significantly affect other physical properties, including moisture resistance.
Specific examples of the acyl group having 2 to 20 carbon atoms are the same as those exemplified above for Y, and preferred acyl groups are also the same.

In formula (1), n is the number of repeats and is an average value. Its value ranges from more than 0 to 30. From the standpoint of handleability, it is preferably more than 0 to 20, and more preferably more than 0 to 10. The number n can be calculated from the number average molecular weight (Mn) obtained by GPC measurement.

The phosphorus content of the phosphorus-containing modified epoxy resin of the present invention is 1.0 to 6.0% by mass. If the phosphorus content is less than 1.0% by mass, flame retardancy may be insufficient. If the phosphorus content exceeds 6.0% by mass, solvent solubility may be significantly reduced. A phosphorus content of 1.0 to 5.0% by mass is preferred, and 1.5 to 4.0% by mass is more preferred.

The epoxy equivalent (g/eq.) of the phosphorus-containing modified epoxy resin of the present invention is in the range of 300 or more and less than 5,000. Within this range, the phosphorus-containing modified epoxy resin of the present invention itself can participate in the curing reaction and be incorporated into a crosslinked structure. The epoxy equivalent is preferably in the range of 350 to 2,000, more preferably in the range of 400 to 1,500.

The number average molecular weight (Mn) of the phosphorus-containing modified epoxy resin of the present invention is preferably 500 to 10,000. If Mn is less than 500, there is a risk that the introduction of a structure that improves the flame retardancy of the cured product will be reduced, which is undesirable. If Mn is greater than 10,000, there is a risk that the solution viscosity will increase, making handling during the production of a cured product difficult, which is undesirable. Mn is more preferably 700 to 7,000, and even more preferably 900 to 5,000. The Mn of the phosphorus-containing modified epoxy resin can be measured by the gel permeation chromatography (GPC) method described in the examples.

The phosphorus-containing 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. A preferred production method is a production method in which a bifunctional epoxy resin represented by general formula (4) is reacted with a diester compound represented by general formula (5).

In the general formula (4), G is a glycyl group, m is the number of repetitions, and the average value is 0 or more and 6 or less.
In general formula (5), Q is independently an acyl group having 2 to 20 carbon atoms or a hydrogen atom. 5 mol % or more of Q is an acyl group having 2 to 20 carbon atoms, and the remainder is a hydrogen atom.
Here, the diester compound represented by general formula (5) is selected from diester compounds in which both Qs are acyl groups, monoester compounds in which one is an acyl group and the other is a hydrogen atom, and diphenol compounds in which both are hydrogen atoms, and may be a diester compound or a monoester compound, or a mixture containing a diester compound and/or a monoester compound. The diester compound is preferably a diester compound in which both Qs are acyl groups, or a mixture in which the main component (50% or more) is a diester compound. The acylation rate decreases when the amount of monoester compound or diphenol compound is large.

^X1 in general formula (4) and ^X2 in general formula (5) are selected so as to give X in general formula (1). Therefore, ^{either X1} in general formula (4) or ^X2 in general formula (5) must contain a structure represented by formula (2). For example, when either ^X1 in general formula (4) or ^X2 in formula (5) contains a structure represented by formula (2), the other may or may not contain a structure represented by formula (2).

The phosphorus-containing modified epoxy resin of the present invention necessarily contains the structure represented by formula (2). As long as this requirement is satisfied, the structure represented by formula (2) may be contained in any of the starting bifunctional epoxy resin, diester compound, and bifunctional phenol compound, and the proportion thereof is not limited.
As long as ^X1 in general formula (4) or ^X2 in general formula (5) contains at least the structure represented by formula (2), another divalent group can be introduced as ^X1 or ^X2 .

The bifunctional epoxy resin used in the production method of the present invention is an epoxy resin represented by general formula (4), such as 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 formula (4) above.

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. More than this amount reduces production efficiency, while less than this amount increases the amount of high-molecular-weight epoxy resin produced, making it unsuitable as a raw material for phosphorus-containing modified epoxy resin.

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 a bifunctional phenol compound is reacted with an epihalohydrin, m typically becomes greater than 0. To achieve m of 0, epoxy resins produced by known methods can be highly purified by distillation, crystallization, or other techniques, or the bifunctional phenol compound can be allylated and then epoxidized by oxidizing the olefin moiety.

The diester compounds used in the manufacturing method of the present invention can be obtained, for example, by acylation of a bifunctional phenol compound 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 (4) is 0 as the raw material, the phosphorus-containing 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 introduce an appropriate amount of secondary hydroxyl groups into the phosphorus-containing modified epoxy resin of the present invention, as long as this does not significantly affect other physical properties, including moisture resistance.

The bifunctional epoxy resin or diester compound used in the manufacturing method of the present invention contains a structure represented by formula (2). The total phosphorus content of the raw material bifunctional epoxy resin and diester compound, and the bifunctional phenol compound used in combination as needed, determines the phosphorus content of the phosphorus-containing modified epoxy resin of the present invention. Therefore, the type and amount of the bifunctional epoxy resin, diester compound, and bifunctional phenol compound used can be adjusted depending on the desired phosphorus content.

The amount of bifunctional epoxy resin and diester compound used is preferably 0.3 to 1.0 equivalents of the total of ester groups and phenolic hydroxyl groups per equivalent of epoxy group. This equivalent ratio facilitates the promotion of high molecular weight polymerization with epoxy groups at the molecular terminals. It is also possible to replace a portion of the diester compound with a bifunctional phenol compound. As described above, this allows for the presence of an appropriate amount of secondary hydroxyl groups in the phosphorus-containing modified epoxy resin of the present invention, thereby enabling fine adjustment of physical properties.
In the production method, a polymerization reaction occurs, the molecular weight of the resulting phosphorus-containing modified epoxy resin increases, and a portion of the secondary hydroxyl groups of the phosphorus-containing modified epoxy resin is esterified.

A catalyst may be used in the production method. Any compound with catalytic activity that promotes the reaction between epoxy groups and ester groups may be used as the catalyst. Examples include tertiary amines, cyclic amines, imidazole compounds, organophosphorus compounds, and quaternary ammonium salts. These catalysts may be used alone or in combination of two or more.

Examples of tertiary amines include triethylamine, tri-n-propylamine, tri-n-butylamine, triethanolamine, benzyldimethylamine, and 2,4,6-tris(dimethylaminomethyl)phenol.

Examples of cyclic amines include 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 imidazole compounds include 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, and tetrabutylphosphonium hydride. and phosphonium salts such as methyl cyclohexyl phosphonium chloride, trimethyl cyclohexyl phosphonium bromide, trimethyl benzyl phosphonium chloride, trimethyl benzyl phosphonium bromide, tetraphenyl phosphonium bromide, triphenyl methyl phosphonium bromide, triphenyl methyl phosphonium iodide, triphenyl ethyl phosphonium chloride, triphenyl ethyl phosphonium bromide, triphenyl ethyl phosphonium iodide, triphenyl benzyl phosphonium chloride, and triphenyl benzyl phosphonium bromide.

Examples of quaternary ammonium salts include 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 phosphorus-containing modified epoxy resin, potentially deteriorating the insulating properties of the printed wiring board or shortening the pot life of the composition. Therefore, the content of catalyst-derived nitrogen in the phosphorus-containing modified epoxy resin is preferably 0.5% by mass or less, more preferably 0.3% by mass or less. Furthermore, the content of catalyst-derived phosphorus in the phosphorus-containing modified epoxy resin is preferably 0.5% by mass or less, more preferably 0.3% by mass or less.

In the manufacturing method of the present invention, a reaction solvent may be used. Any solvent capable of dissolving the phosphorus-containing 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. Furthermore, when the resulting phosphorus-containing modified epoxy resin is used as a varnish, these solvents may be used as dilution solvents to achieve an appropriate solids concentration for the intended use. The solids concentration of the phosphorus-containing modified epoxy resin varnish is not limited, but can be appropriately selected depending on the intended use, for example, from a range of 10 to 90% by mass, preferably 20 to 80% by mass, in terms of nonvolatile content (solids).

Examples of aromatic solvents include benzene, toluene, xylene, etc.

Examples of ketone solvents include acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, 2-heptanone, 4-heptanone, 2-octanone, cyclohexanone, acetylacetone, dioxane, 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 monoalkyl 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 the alkyl ether 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, dimethyl sulfoxide, sulfolane, N-methyl-2-pyrrolidone, etc.

In this production method, the solids concentration during the reaction is preferably 35 to 100% by mass. If a highly viscous product is produced during the reaction, the reaction can be continued by adding additional solvent. After the reaction is complete, the solvent can be removed or further added as needed.

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 phosphorus-containing modified 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 70 to 210°C, and even more preferably 90 to 200°C. The reaction time is typically 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, indirect cooling, or a combination of these.

The resin composition of the present invention is a resin composition containing at least the phosphorus-containing 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.

In this invention, a curing agent refers to a substance that contributes to the crosslinking reaction and/or chain extension reaction with the phosphorus-containing 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 phosphorus-containing 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, more preferably 0.5 to 80 parts by mass, and even more preferably 1 to 50 parts by mass, per 100 parts by mass of the phosphorus-containing modified epoxy resin of the present invention. Note that this refers to the amount of non-volatile content (solid content) in the resin composition.
In the present invention, the term "solid content" means components excluding the solvent, and includes not only solid phosphorus-containing modified epoxy resins and epoxy resins, but also semi-solid and viscous liquid substances.

There are no particular restrictions on the curing agent used in the resin composition of the present invention, and any commonly known epoxy resin curing agent can be used. From the perspective of enhancing heat resistance, preferred curing agents include phenolic resins, amide compounds, imidazole compounds, and active ester curing agents. These curing agents may be used alone or in combination of two or more types.

Examples of phenolic resins 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, Examples thereof include 8-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,4-dihydroxynaphthalene, 2,5-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 2,8-dihydroxynaphthalene, and the like, as well as allylated products or polyallylated products of the above dihydroxynaphthalenes, allylated bisphenol A, allylated bisphenol F, allylated phenol novolak, and allylated pyrogallol.

Examples of amide compounds include dicyandiamide and its derivatives, polyamide resins, etc.

Examples of imidazole compounds 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'-methylimidazole] Examples of suitable imidazole compounds 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 imidazole compounds. Note that, because imidazole compounds 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. Examples of such 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 such 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, acrylic ester resins, melamine resins, urea resins, cationic polymerization agents, amine compounds, acid anhydrides, tertiary amines, organic phosphines, phosphonium salts, tetraphenylboron salts, organic acid dihydrazides, boron halide amine complexes, polymercaptan curing agents, isocyanate compounds, polyisocyanate compounds, blocked isocyanate compounds, 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 phosphorus-containing modified epoxy resin of the present invention. The use of other epoxy resins can compensate for insufficient physical properties or improve various physical properties. Epoxy resins preferably have two or more epoxy groups in the molecule, and more preferably have 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 may be used alone, or two or more types of epoxy resins of the same type may be used in combination, or different types of epoxy resins may 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, trimellitic acid type epoxy resins, etc.

Examples of alicyclic epoxy compounds include aliphatic cyclic epoxy resins such as Celoxide 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, etc.), phenoxy resins, etc.

When the phosphorus-containing modified epoxy resin of the present invention and another epoxy resin are used in the resin composition of the present invention, the amount of the phosphorus-containing modified epoxy resin in the total components of the phosphorus-containing modified epoxy resin and the epoxy resin as solid contents is preferably 1 to 99 mass %, more preferably 50 mass % or more, and even more preferably 80 mass % or more.
When the phosphorus-containing modified epoxy resin of the present invention is used together with another epoxy resin, the curing agent is preferably contained in an amount of 0.1 to 100 parts by mass, more preferably 0.5 to 80 parts by mass, and even more preferably 1 to 50 parts by mass, as solid content, per 100 parts by mass of the total solid content of the phosphorus-containing modified epoxy resin and the other epoxy resin.

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, multifunctional 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 weight or less, particularly 20 to 80% by weight, based on nonvolatile content. The appropriate type and amount are selected appropriately 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, and 1-methoxy-2-propanol, are preferred, with the amount used being 40 to 80% by weight based on nonvolatile content. For adhesive film applications, ketones, acetate esters, carbitols, aromatic hydrocarbons, dimethylformamide, dimethylacetamide, and N-methylpyrrolidone are preferred, with the amount used being 30 to 60% by weight based on nonvolatile content.

If necessary, a curing accelerator or catalyst can be used in the resin composition of the present invention. Examples of curing accelerators or catalysts include imidazole compounds, 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 in the resin composition (all epoxy resins including the phosphorus-containing modified epoxy resin of the present invention). 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 they do not reduce reliability. 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 described above 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, and ion trapping agents.

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 also contain a thermoplastic resin. Examples of thermoplastic resins include phenoxy resin, phosphorus-containing phenoxy resin, polyurethane resin, polyester resin, polyethylene resin, polypropylene resin, polystyrene resin, ABS resin, AS resin, vinyl chloride resin, polyvinyl acetate resin, polymethyl methacrylate resin, polycarbonate resin, polyacetal resin, cyclic polyolefin resin, polyamide resin, thermoplastic polyimide resin, polyamideimide resin, polytetrafluoroethylene resin, polyetherimide resin, polyphenylene ether resin, modified polyphenylene ether resin, polyethersulfone resin, polysulfone resin, polyetheretherketone resin, polyphenylene sulfide resin, and polyvinyl formal resin. Phosphorus-containing phenoxy resin is preferred in terms of compatibility, while polyphenylene ether resin and modified polyphenylene ether resin 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 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 a phosphorus-containing modified epoxy resin, a curing agent, and various 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 a semi-cured resin product such as a resin sheet, a resin-coated copper foil, or a prepreg, the curing reaction of the resin composition is usually allowed to proceed to an extent that the shape can be maintained by heating, etc. When the resin composition contains a solvent, most of the solvent is usually removed by techniques such as heating, reducing pressure, or air drying, but 5% by mass or less 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 composition. For example, the prepreg can be obtained by heating and drying at 100 to 200°C for 1 to 40 minutes. The amount of resin composition in the prepreg is preferably 30 to 80% by mass.

A method for manufacturing a laminate using the prepreg or insulating adhesive sheet of the present invention will be described. When forming a laminate using prepreg, one or more prepregs are laminated together, with metal foil placed on one or both sides to form a laminate, and the 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 ensure that the resin composition cures. If the pressure is too low, air bubbles may remain inside the resulting laminate, potentially reducing its electrical properties. Therefore, it is desirable to pressurize it 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 circuit surface is then treated with an acid solution for blackening to obtain the inner layer material. An insulating layer is then formed on one or both circuit-forming surfaces of this inner layer material using a prepreg or insulating adhesive sheet, 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 flame retardancy.

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 various equivalents is "g/eq."

(1) 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 40 ° C. The eluent was tetrahydrofuran (THF), the flow rate was 1.0 mL / min, and the detector was a differential refractive index detector. The measurement sample was 0.1 g of solid content dissolved in 10 mL of THF and filtered through a 0.45 μm microfilter, and 50 μL was used. A calibration curve was created using standard polystyrene (manufactured by Tosoh Corporation, PStQuick A, PStQuick B, PStQuick C). 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 500 to 4000 ^cm was measured.

(3) Epoxy equivalent:
Measurements were carried out in accordance with JIS K7236. 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) Phosphorus content:
Sulfuric acid, hydrochloric acid, and perchloric acid were added to the phosphorus-containing modified epoxy resin, and the resin was heated and wet-ashed to convert all phosphorus atoms to orthophosphate. Metavanadate and molybdate were reacted in the sulfuric acid acidic solution, and the absorbance at 420 nm of the resulting phosphorus vanadomolybdate complex was measured. The phosphorus content (P/resin) was calculated in percentage using a pre-prepared calibration curve. For solvent-diluted products (resin varnishes), the solids content was calculated from the nonvolatile content.

(5) Non-volatile content (solid content):
The measurement was performed in accordance with JIS K 7235. The drying temperature was 200°C and the drying time was 60 minutes.

(6) Flame retardancy:
Evaluation was carried out by the UL94 (Underwriters Laboratories Inc.) V test. Test specimens were prepared in accordance with UL94-V using the method described below. Five test specimens were tested, and the total duration of flaming combustion after the first and second flame contact (five specimens were each flamed twice, for a total of 10 times) was used to evaluate the flame resistance as V-0, V-1, or V-2, which is the standard's evaluation criteria. V-0 represents the best flame retardancy, followed by V-1 and V-2, which are inferior in order. However, specimens that burned completely were marked with an X.

(7) Solubility:
The phosphorus-containing modified epoxy resin was made into a resin varnish with a resin content of 30% using cyclohexanone, and the same amount of bisphenol A type epoxy resin (YD-128, manufactured by Nippon Steel Chemical & Material Co., Ltd.) was added, and the mixture was shaken in a shaker for 1 hour, and then left to stand in a thermostatic bath at 25°C for 24 hours, after which the state was visually inspected. The evaluation is as follows.
◯: Uniform and transparent. ×: Cloudy or separated.

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

A1: Bisphenol A epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd., YD-128, epoxy equivalent 186, m≒0.09)
A2: 3,3',5,5'-tetramethyl-4,4'-biphenol epoxy resin (manufactured by Mitsubishi Chemical Corporation, YX-4000, epoxy equivalent 196, m≒0.11)

B1: 10-(2,5-diacetoxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (phosphorus content 7.6%, active equivalent 204)
B2: 10-(2,7-diacetoxynaphthyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (phosphorus content 6.7%, active equivalent 229)
B3: 2,2-bis(4-acetoxyphenyl)propane (Tokyo Chemical Industry Co., Ltd., active equivalent: 156)
Here, the active equivalent refers to the equivalent of an active ester group.

[Phenol compounds]
C1: 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (manufactured by Sanko Co., Ltd., HCA-HQ, phosphorus content 9.5%, hydroxyl equivalent 162)
C2: 10-(2,7-dihydroxynaphthyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (manufactured by Sanko Co., Ltd., HCA=NQ, phosphorus content 8.2%, hydroxyl equivalent 187)

[catalyst]
D1: 4-dimethylaminopyridine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
D2: 2-ethyl-4-methylimidazole (Curesol 2E4MZ, manufactured by Shikoku Chemicals Corporation)

[Acid anhydride]
E1: Acetic anhydride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[Curing agent]
H1: Phenol novolak resin (manufactured by Aica Kogyo Co., Ltd., Shounol BRG-557, hydroxyl group equivalent: 105)
H2: 2-ethyl-4-methylimidazole (Curesol 2E4MZ, manufactured by Shikoku Chemicals Corporation)
[Solvents]
S1: Cyclohexanone

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 C1, 315 parts of E1, 0.05 parts of dibutyltin maleate, and 186 parts of acetic acid at room temperature, and the mixture was heated to 110°C with stirring under nitrogen gas flow, and reacted for 2 hours. Thereafter, the mixture was dried under reduced pressure at 130°C and 1.3 kPa (10 torr) for 3 hours, yielding 98 parts of B1.

Synthesis Example 2
The glass reaction vessel was charged with 100 parts of C2, 272 parts of E1, 0.04 parts of dibutyltin maleate, and 160 parts of acetic acid at room temperature, and the mixture was heated to 110°C while stirring under nitrogen gas flow, and reacted for 2 hours. Thereafter, the mixture was dried under reduced pressure at 130°C and 10 torr for 3 hours, yielding 98 parts of 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 A1, 37 parts of B1, and 57 parts of S1 at room temperature, and the mixture was heated to 130°C while stirring and nitrogen gas was passed through. 0.1 part of D1 was added, and the mixture was then heated to 145°C and reacted for 7 hours at a temperature ranging from 145 to 150°C. 261 parts of S1 was used as a dilution solvent for dilution and mixing, yielding a phosphorus-containing modified epoxy resin (R1) with a non-volatile content (solid content) of 30%.

Examples 2 to 7, Comparative Examples 1 and 2
A phosphorus-containing modified epoxy resin was obtained by the same procedure as in Example 1, using the amounts (parts) of each raw material charged and the reaction times shown in Table 1. The epoxy equivalent, Mn, phosphorus content, and solubility of the obtained phosphorus-containing modified epoxy resin were measured. The results are shown in Table 1. In the table, "molar ratio" represents the molar ratio of the bifunctional epoxy resin to the diester compound and bifunctional phenol compound, and "acylation rate" represents the content (mol %) of acyl groups in the total Z in formula (1).

Example 8
A resin composition varnish was obtained by blending 100 parts (30 parts solids) of phosphorus-containing modified epoxy resin varnish R1, 8.5 parts of curing agent H1, and 0.3 parts of H2, and dissolving them in a mixed solvent prepared with methyl ethyl ketone (MEK), propylene glycol monomethyl ether (PM), and N,N-dimethylformamide (DMF). The resulting 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 resulting prepreg was loosened and sieved to produce prepreg powder (100 mesh pass). The resulting 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 a 1.6 mm thick laminate. Both sides of the resulting laminate were etched to obtain test specimens for flame retardancy evaluation. The flame retardancy evaluation results are shown in Table 2.

Examples 9 and 10 and Comparative Example 3
The components were blended in the amounts (parts) shown in Table 2, and the same operations as in Example 8 were carried out to obtain a resin composition varnish, a prepreg, and a test piece for evaluating flame retardancy. The same tests as in Example 8 were carried out, and the results are shown in Table 2.

As can be seen from Table 1, the phosphorus-containing modified epoxy resin of the present invention has excellent solubility, and as can be seen from Table 2, the cured product made from the phosphorus-containing modified epoxy resin composition of the present invention also has excellent flame retardancy.

The phosphorus-containing modified epoxy resin and resin composition of the present invention are applicable to various fields such as adhesives, paints, civil engineering and building materials, and insulating materials for electric and electronic components, and are particularly useful in the electric and electronic fields as insulating casting materials, laminate materials, sealing materials, etc. The phosphorus-containing modified epoxy resin and resin composition containing the same of the present invention are suitable for use in multilayer printed wiring boards, laminates for electric and electronic circuits such as capacitors, adhesives such as film adhesives and liquid adhesives, semiconductor sealing materials, underfill materials, interchip fill materials for 3D-LSIs, insulating sheets, prepregs, heat dissipation substrates, etc.

Claims (10)

A phosphorus-containing modified epoxy resin represented by the following formula (1), having an epoxy equivalent of 300 g/eq. or more and less than 5,000 g/eq., a number average molecular weight of 900 to 5,000, and a phosphorus content of 1.0 to 6.0 mass%.
In the formula, X is independently a divalent group and has at least a phosphorus-containing divalent group represented by the following 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 is an acyl group. n is the average number of repeating units and is greater than 0 and 30 or less.
In the formula, A is a trivalent aromatic hydrocarbon group having 6 to 20 carbon atoms. ^R1 and ^R2 are each independently a hydrocarbon group having 1 to 20 carbon atoms which may have a heteroatom, and may be linear, branched, or cyclic, or ^R1 and ^R2 may bond to form a cyclic structure. k1 and k2 are each independently 0 or 1. A resin composition comprising the phosphorus-containing modified epoxy resin according to claim 1 and a curing agent. 3. The resin composition according to claim 2 , comprising 0.1 to 100 parts by mass of a curing agent per 100 parts by mass of the phosphorus-containing modified epoxy resin. A resin composition comprising the phosphorus-containing modified epoxy resin according to claim 1 , an epoxy resin, and a curing agent, wherein the mass ratio of the phosphorus-containing modified epoxy resin to the epoxy resin is 99/1 to 1/99. 5. The resin composition according to claim 4, comprising 0.1 to 100 parts by mass of a curing agent per 100 parts by mass of the phosphorus-containing modified epoxy resin and the epoxy resin combined. 3. The resin composition according to claim 2, wherein the curing agent is at least one selected from the group consisting of acrylic ester resins, melamine resins, urea resins, phenolic resins, acid anhydrides, 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 according to claim 2 . A laminate for electrical and electronic circuits made using the resin composition described in claim 2. 2. The method for producing a phosphorus-containing modified epoxy resin according to claim 1, wherein the phosphorus-containing modified epoxy resin is obtained by reacting a bifunctional epoxy resin represented by the following formula (4) with a compound represented by the following formula (5):
Here, ^X1 and ^X2 are independently a divalent group, and one or both of ^X1 and ^X2 has at least a phosphorus-containing divalent group represented by the above formula (2). G is a glycidyl group, Q is independently an acyl group having 2 to 20 carbon atoms or a hydrogen atom, and 5 mol% or more of Q is an acyl group. m is the average number of repeating groups and is 0 to 6. 10. The method for producing a phosphorus-containing modified epoxy resin according to claim 9, wherein the compound represented by formula ( 5 ) is a compound in which at least one Q is an acyl group, or a mixture of a compound in which at least one Q is an acyl group and a compound in which both Qs are hydrogen atoms.