JP7474054B2 - Benzoxazine compound, curable resin composition, adhesive, adhesive film, cured product, circuit board, interlayer insulating material, and multilayer printed wiring board - Google Patents

Description

The present invention relates to a benzoxazine compound that can be used in a curable resin composition that has excellent flexibility before curing and excellent dielectric properties after curing. The present invention also relates to a curable resin composition containing the benzoxazine compound, and an adhesive, an adhesive film, a cured product, a circuit board, an interlayer insulating material, and a multilayer printed wiring board that use the curable resin composition.

Curable resins such as epoxy resins, which have low shrinkage and excellent adhesion, insulation, and chemical resistance, are used in many industrial products. In particular, curable resin compositions used as interlayer insulating materials for printed wiring boards and the like require dielectric properties such as low dielectric constant and low dielectric tangent. As curable resin compositions with such excellent dielectric properties, for example, Patent Documents 1 and 2 disclose curable resin compositions containing a curable resin and a compound having a specific structure as a curing agent. However, such curable resin compositions have a problem in that it is difficult to achieve both flexibility before curing and dielectric properties after curing.

JP 2017-186551 A International Publication No. 2016/114286

The present invention aims to provide a benzoxazine compound that can be used in a curable resin composition that has excellent flexibility before curing and excellent dielectric properties after curing. The present invention also aims to provide a curable resin composition containing the benzoxazine compound, and an adhesive, an adhesive film, a cured product, a circuit board, an interlayer insulating material, and a multilayer printed wiring board made using the curable resin composition.

The present invention relates to a benzoxazine compound having, in the molecule, a diamine residue having an aliphatic skeleton having 4 or more carbon atoms and/or a triamine residue having an aliphatic skeleton having 4 or more carbon atoms, and a benzoxazine ring.
The present invention will be described in detail below.

The inventors discovered that by using a benzoxazine compound having a specific structure, it is possible to obtain a curable resin composition that has excellent flexibility before curing and excellent dielectric properties after curing, and thus completed the present invention.

The benzoxazine compound of the present invention has a diamine residue (hereinafter also simply referred to as "diamine residue") having an aliphatic skeleton having 4 or more carbon atoms and/or a triamine residue (hereinafter also simply referred to as "triamine residue") having an aliphatic skeleton having 4 or more carbon atoms in the molecule. Since the benzoxazine compound of the present invention has the diamine residue and/or the triamine residue, when it is blended in a curable resin composition, it can improve the flexibility of the curable resin composition before curing. In addition, since the benzoxazine compound of the present invention has the diamine residue and/or the triamine residue and has a benzoxazine ring, the cured product of the obtained curable resin composition has excellent dielectric properties such as low dielectric constant and low dielectric loss tangent.
In this specification, the above-mentioned "residue" refers to the structure of the portion other than the functional group that is used for bonding. For example, a "diamine residue" refers to the structure of the portion other than the amino group in the raw material diamine.

The lower limit of the number of carbon atoms in the aliphatic skeleton of the diamine residue and the triamine residue is 4. When the number of carbon atoms in the aliphatic skeleton of the diamine residue and the triamine residue is 4 or more, the obtained curable resin composition has excellent flexibility before curing and excellent dielectric properties after curing. The lower limit of the number of carbon atoms in the aliphatic skeleton of the diamine residue and the triamine residue is preferably 7, and more preferably 8.
Further, there is no particular upper limit on the number of carbon atoms in the aliphatic skeleton of the diamine residue and the triamine residue, but the substantial upper limit is 90.

The aliphatic skeleton of the diamine residue and the triamine residue may be substituted.
When the aliphatic skeleton of the diamine residue and the triamine residue is substituted, examples of the substituent include a halogen atom, an aryl group, an alkoxy group, a nitro group, and a cyano group.

The diamine from which the diamine residue is derived may be an aliphatic diamine.
Examples of the aliphatic diamine include aliphatic diamines derived from dimer acids, linear or branched aliphatic diamines, aliphatic ether diamines, alicyclic diamines, etc. Among these, aliphatic diamines derived from dimer acids are preferred.
Examples of the aliphatic diamine derived from the dimer acid include dimer acids that are dimers of aliphatic acids having 10 to 30 carbon atoms, such as oleic acid, linoleic acid, linolenic acid, palmitoleic acid, and elaidic acid, and hydrogenated dimer diamines thereof.
Examples of the linear or branched aliphatic diamine include 1,4-butanediamine, 1,6-hexanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,14-tetradecanediamine, 1,16-hexadecanediamine, 1,18-octadecanediamine, 1,20-eicosanediamine, 2-methyl-1,8-octanediamine, 2-methyl-1,9-nonanediamine, and 2,7-dimethyl-1,8-octanediamine.
Examples of the aliphatic ether diamine include 2,2'-oxybis(ethylamine), 3,3'-oxybis(propylamine), 1,2-bis(2-aminoethoxy)ethane, and the like.
Examples of the alicyclic diamine include 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, cyclohexanediamine, methylcyclohexanediamine, and isophoronediamine.

In addition, the diamine from which the above diamine residue is derived can be a diamine obtained by reacting the above aliphatic diamine with an acid dianhydride, which has an acid dianhydride residue in its main chain and amino groups derived from an aliphatic diamine at both ends.

Examples of the above-mentioned acid dianhydrides include pyromellitic anhydride, 3,3'-oxydiphthalic anhydride, 3,4'-oxydiphthalic anhydride, 4,4'-oxydiphthalic anhydride, 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 4,4'-bis(2,3-dicarboxylphenoxy)diphenyl ether acid dianhydride, p-phenylene bis(trimellitic acid monoester acid anhydride), 2,3,3',4'-biphenyl tetracarboxylic acid anhydride, etc. Among these, 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride is preferred.

The triamine from which the triamine residue is derived may be an aliphatic triamine.
Examples of the aliphatic triamine include aliphatic triamines derived from trimer acids, linear or branched aliphatic triamines, etc. Among these, the aliphatic triamines derived from trimer acids are preferred.
Examples of the aliphatic triamine derived from the trimer acid include trimer triamines derived from trimer acids, which are trimers of aliphatic acids having from 10 to 30 carbon atoms, such as oleic acid, linoleic acid, linolenic acid, palmitoleic acid, and elaidic acid, and hydrogenated trimer triamines thereof.
Examples of the linear or branched aliphatic triamine include 3,3'-diamino-N-methyldipropylamine, 3,3'-diaminodipropylamine, diethylenetriamine, bis(hexamethylene)triamine, and 2,2'-bis(methylamino)-N-methyldiethylamine.
The aliphatic triamines may be used in a mixture with the aliphatic diamines.

Among the above aliphatic diamines and/or aliphatic triamines, examples of commercially available ones include aliphatic diamines and/or aliphatic triamines manufactured by BASF and aliphatic diamines and/or aliphatic triamines manufactured by Croda.
Examples of the aliphatic diamines and/or aliphatic triamines manufactured by BASF include Versamine 551, Versamine 552, and the like.
Examples of the aliphatic diamines and/or aliphatic triamines manufactured by Croda include Priamine 1071, Priamine 1073, Priamine 1074, Priamine 1075, and the like.

The benzoxazine compound of the present invention preferably has a structure represented by the following formula (1-1) or (1-2), the following formula (2-1) or (2-2), or the following formula (3) as a structure containing the diamine residue and/or the triamine residue, and the benzoxazine ring. By having a structure represented by the following formula (1-1) or (1-2), the following formula (2-1) or (2-2), or the following formula (3), the benzoxazine compound of the present invention has superior flexibility before curing and dielectric properties after curing.

In formula (1-1), A is the above diamine residue, and X and X' are each independently a hydrogen atom or any substituent.
In formula (1-2), A is the above triamine residue, and X, X', and X'' each independently represent a hydrogen atom or any substituent.

In formula (2-1), A is the diamine residue, B and B' are each independently an arbitrary organic group, R and R' are each independently a hydrogen atom or an arbitrary substituent, B and each R may be bonded to form a ring structure, B' and each R' may be bonded to form a ring structure, and Y and Y' are each independently a hydrogen atom or an arbitrary substituent.
In formula (2-2), A is the triamine residue; B, B', and B'' are each independently any organic group; R, R', and R'' are each independently a hydrogen atom or any substituent; B and each R may be bonded to form a ring structure; B' and each R may be bonded to form a ring structure; B'' and each R'' may be bonded to form a ring structure; and Y, Y', and Y'' are each independently a hydrogen atom or any substituent.

In formula (3), A and A' are each independently the above diamine residue, B is any organic group, R and R' are each independently a hydrogen atom or any substituent, B and R may be bonded to form a ring structure, B and R' may be bonded to form a ring structure, and X and X' are each independently a hydrogen atom or any substituent.

When X and X' in the above formula (1-1) and X, X', and X'' in the above formula (1-2) are substituents, examples of the substituent include a halogen atom, a linear or branched alkyl group, a linear or branched alkenyl group, an alicyclic group, an aryl group, an alkoxy group, a nitro group, a cyano group, and the like.
In addition, when X and X' in the above formula (1-1) and X, X', and X'' in the above formula (1-2) are substituents, the hydrogen atoms in the aromatic ring may be substituted with a plurality of the substituents.

When Y and Y' in the above formula (2-1) and Y, Y', and Y'' in the above formula (2-2) are substituents, examples of the substituent include a linear or branched alkyl group, a linear or branched alkenyl group, an alicyclic group, an aryl group, or a phenyl group having an alkyl group or an alkoxy group as a substituent.
Furthermore, when Y and Y' in the above formula (2-1) and Y, Y', and Y'' in the above formula (2-2) are substituents, the hydrogen atoms in the aromatic rings may be substituted with a plurality of the substituents.

It is preferable that B and each R, and B' and each R' in the above formula (2-1), and B and each R, B' and each R', and B" and each R" in the above formula (2-2) form a ring structure. The ring structure is preferably an imide ring.
In particular, the structure represented by the above formula (2-1) is preferably a structure represented by the following formula (4).

In formula (4), A is the above-mentioned diamine residue, C and C' are acid dianhydride residues, and Y and Y' are each independently a hydrogen atom or any substituent.

When Y and Y′ in the above formula (4) are substituents, examples of the substituent include a linear or branched alkyl group, a linear or branched alkenyl group, an alicyclic group, an aryl group, and a phenyl group having an alkyl group or an alkoxy group as a substituent.
Furthermore, when Y and Y′ in the above formula (4) are substituents, the hydrogen atoms in the aromatic ring may be substituted with a plurality of such substituents.

The acid dianhydrides from which the acid dianhydride residues represented by C and C' in formula (4) are derived include those similar to the acid dianhydrides in the reaction between the aliphatic diamine and the acid dianhydride described above.

When X and X′ in the above formula (3) are substituents, examples of the substituent include a halogen atom, a linear or branched alkyl group, a linear or branched alkenyl group, an alicyclic group, an aryl group, an alkoxy group, a nitro group, and a cyano group.
Furthermore, when X and X′ in the above formula (3) are substituents, the hydrogen atoms in the aromatic ring may be substituted with a plurality of such substituents.

In the above formula (3), B and R, and B and R′, preferably form a ring structure. The ring structure is preferably an imide ring.
In particular, the structure represented by the above formula (3) is preferably a structure represented by the following formula (5).

In formula (5), A and A' are each independently the above diamine residue, C is an acid dianhydride residue, and X and X' are each independently a hydrogen atom or any substituent.

When X and X′ in the above formula (5) are substituents, examples of the substituent include a halogen atom, a linear or branched alkyl group, a linear or branched alkenyl group, an alicyclic group, an aryl group, an alkoxy group, a nitro group, and a cyano group.
Furthermore, when X and X′ in the above formula (5) are substituents, the hydrogen atoms in the aromatic ring may be substituted with a plurality of such substituents.

It is also preferable that the benzoxazine compound of the present invention has a repeating structural unit represented by the following formula (6), (7), or (8) as a structure containing the diamine residue and the benzoxazine ring. By having a repeating structural unit represented by the following formula (6), (7), or (8), the benzoxazine compound of the present invention has excellent flexibility before curing and excellent dielectric properties and mechanical strength after curing.

In formula (6), A is the diamine residue, and Z is a bond or any organic group. Some or all of the hydrogen atoms in the aromatic ring in formula (6) may be substituted with any substituent.

In formula (7), A is the above-mentioned diamine residue, B and B' are each independently any organic group, R and R' are each independently a hydrogen atom or any substituent, B and R may be bonded to form a ring structure, B' and R' may be bonded to form a ring structure, and W is any organic group.

In formula (8), A and A' are each independently the diamine residue, B is an arbitrary organic group, R and R' are each independently a hydrogen atom or an arbitrary substituent, B and R may be bonded to form a ring structure, B and R' may be bonded to form a ring structure, and Z is a bond or an arbitrary organic group. The hydrogen atoms of the aromatic ring in formula (8) may be partially or completely substituted with an arbitrary substituent.

When the hydrogen atom of the aromatic ring in the above formula (6) is replaced with any substituent, examples of the substituent include a halogen atom, a linear or branched alkyl group, a linear or branched alkenyl group, an alicyclic group, an aryl group, an alkoxy group, a nitro group, a cyano group, etc.

It is preferable that W in the above formula (7) is the above-mentioned diamine residue or a diamine residue that does not have an aliphatic skeleton having 4 or more carbon atoms.

In the above formula (7), B and each R, and B' and each R' preferably form a ring structure. The ring structure is preferably an imide ring.

When the hydrogen atom of the aromatic ring in the above formula (8) is replaced with any substituent, examples of the substituent include a halogen atom, a linear or branched alkyl group, a linear or branched alkenyl group, an alicyclic group, an aryl group, an alkoxy group, a nitro group, a cyano group, etc.

In the above formula (8), B and R, and B and R' preferably form a ring structure. The ring structure is preferably an imide ring.

The preferred lower limit of the molecular weight of the benzoxazine compound of the present invention is 300, and the preferred upper limit is 200,000. When the molecular weight is within this range, when the benzoxazine compound of the present invention is used in a curable resin composition, the obtained curable resin composition has better flexibility before curing and better dielectric properties of the cured product. The more preferred lower limit of the molecular weight of the benzoxazine compound of the present invention is 400, and the more preferred upper limit is 100,000.
In this specification, the "molecular weight" is the molecular weight calculated from the structural formula for compounds with a specific molecular structure, but may be expressed using the number average molecular weight for compounds with a wide distribution of polymerization degrees and compounds with unspecified modified sites. In this specification, the "number average molecular weight" is a value calculated by measuring using tetrahydrofuran as a solvent by gel permeation chromatography (GPC) and converting it into polystyrene. Examples of columns used when measuring the number average molecular weight calculated in polystyrene terms by GPC include JAIGEL-2H-A (manufactured by Japan Analytical Industry Co., Ltd.).

Among the benzoxazine compounds of the present invention, a method for producing a benzoxazine compound having a structure represented by the above formula (1-1) or (1-2) can be, for example, a method of reacting the above diamine or triamine with a monofunctional phenol compound and paraformaldehyde.

Examples of the monofunctional phenol compound include phenol, o-cresol, m-cresol, p-cresol, 2,3-dimethylphenol, 2,4-dimethylphenol, 2,5-dimethylphenol, 2,6-dimethylphenol, 2-ethylphenol, 3-ethylphenol, 4-ethylphenol, 4-tert-butylphenol, p-octylphenol, p-cumylphenol, dodecylphenol, o-phenylphenol, p-phenylphenol, 1-naphthol, 2-naphthol, m-methoxyphenol, p-methoxyphenol, m-ethoxyphenol, p-ethoxyphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, etc. Of these, phenol is preferable.
These monofunctional phenol compounds may be used alone or in combination of two or more kinds.

Among the benzoxazine compounds of the present invention, examples of a method for producing a benzoxazine compound having a structure represented by the above formula (2-1) or (2-2) include the following methods.
That is, first, the diamine or triamine is reacted with twice the molar amount of an acid dianhydride to obtain an imide oligomer having an acid anhydride group at all of its terminals. The obtained imide oligomer having an acid anhydride group at all of its terminals is reacted with twice the molar amount of 3-aminophenol to obtain an imide oligomer having a phenolic hydroxyl group at all of its terminals. Examples of the method include a method of reacting the obtained imide oligomer having a phenolic hydroxyl group at all of its terminals with a monoamine compound and paraformaldehyde.

Examples of the monoamine compounds include aniline, o-toluidine, m-toluidine, p-toluidine, 2,3-dimethylaniline, 2,4-dimethylaniline, 2,5-dimethylaniline, 3,4-dimethylaniline, 3,5-dimethylaniline, 2-tert-butylaniline, 3-tert-butylaniline, 4-tert-butylaniline, 1-naphthylamine, 2-naphthylamine, 1-aminoanthracene, 2-aminoanthracene, 9-aminoanthracene, 1-aminopyrene, 3-chloroaniline, o-anisidine, m-anisidine, p-anisidine, 1-amino-2-methylnaphthalene, 4-ethylaniline, 4-ethynylaniline, 4-isopropylaniline, 4-(methylthio)aniline, etc. Among these, aniline is preferred.

Among the benzoxazine compounds of the present invention, examples of a method for producing a benzoxazine compound having a structure represented by the above formula (3) include the following methods.
That is, first, an acid dianhydride is reacted with twice the molar amount of the above diamine to obtain an imide oligomer having amino groups at both ends, and then the obtained imide oligomer having amino groups at both ends is reacted with a monofunctional phenol compound and paraformaldehyde.

Among the benzoxazine compounds of the present invention, a method for producing a benzoxazine compound having a structure represented by the above formula (6) can be, for example, a method of reacting the above diamine with a bifunctional phenol compound and paraformaldehyde.

Examples of the bifunctional phenol compounds include 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 4,4'-dihydroxydiphenyl sulfone, 2-hydroxyphenyl ether, 1,1-bis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 1,3-bis(2-(4-hydroxyphenyl)-2)propyl)benzene, and 1,4-bis(2-(4-hydroxyphenyl)-2)propyl)benzene.

In the method for producing a benzoxazine compound having a structure represented by formula (6), a monofunctional phenol compound may be used together with the bifunctional phenol compound.
As the monofunctional phenol compound, a compound similar to that used in the production of a benzoxazine compound having a structure represented by the above formula (1-1) or (1-2) can be used.

Among the benzoxazine compounds of the present invention, examples of a method for producing a benzoxazine compound having a structure represented by the above formula (7) include the following methods.
That is, first, the above diamine is reacted with twice the molar amount of an acid dianhydride to obtain an imide oligomer having an acid anhydride group at both ends. The obtained imide oligomer having an acid anhydride group at both ends is reacted with twice the molar amount of 3-aminophenol to obtain an imide oligomer having phenolic hydroxyl groups at both ends. Examples of the method include a method of reacting the obtained imide oligomer having phenolic hydroxyl groups at both ends with the above diamine (a diamine having an aliphatic skeleton having 4 or more carbon atoms) or a diamine not having an aliphatic skeleton having 4 or more carbon atoms, and paraformaldehyde.

Examples of diamines that do not have an aliphatic skeleton having 4 or more carbon atoms include 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, bis(4-(4-aminophenoxy)phenyl)methane, 2,2-bis(4 1,3-bis(2-(4-aminophenyl)-2-propyl)benzene, 1,4-bis(2-(4-aminophenyl)-2-propyl)benzene, 3,3'-diamino-4,4'-dihydroxyphenylmethane, 4,4'-diamino-3,3'-dihydroxyphenylmethane, 3,3'-diamino-4,4'-dihydroxyphenyl ether, bisaminophenylfluorene, bistruidinefluorene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-diamino-3,3'-dihydroxyphenyl ether, 3,3'-diamino-4,4'-dihydroxybiphenyl, 4,4'-diamino-2,2'-dihydroxybiphenyl, and the like.

Among the benzoxazine compounds of the present invention, examples of a method for producing a benzoxazine compound having a structure represented by the above formula (8) include the following methods.
That is, first, an acid dianhydride is reacted with twice the molar amount of the above diamine to obtain an imide oligomer having amino groups at both ends, and then the obtained imide oligomer having amino groups at both ends is reacted with a bifunctional phenol compound and paraformaldehyde.
As the bifunctional phenol compound, a compound similar to that used in the method for producing the benzoxazine compound having the structure represented by the above formula (6) can be used.

In the method for producing a benzoxazine compound having a structure represented by the above formula (8), a monofunctional phenol compound may be used together with the above bifunctional phenol compound.
As the monofunctional phenol compound, a compound similar to that used in the production of a benzoxazine compound having a structure represented by the above formula (1-1) or (1-2) can be used.

The reaction for forming the benzoxazine ring of the benzoxazine compound of the present invention can be carried out in a solvent or without a solvent. When the reaction is carried out in a solvent, examples of the reaction solvent to be used include aromatic non-polar solvents and halogenated solvents.
Examples of the aromatic non-polar solvent include benzene, toluene, xylene, pseudocumene, and mesitylene.
Examples of the halogen solvent include chloroform and dichloromethane.
Among these, toluene and xylene are preferred, and toluene is more preferred, since they have a small impact on the environment and the human body, are highly versatile, and are inexpensive.
The above solvents may be used alone or in combination of two or more kinds.

When the aromatic non-polar solvent is used as the reaction solvent, alcohols may be used in combination with the aromatic non-polar solvent.
The alcohol is not particularly limited, but is preferably an alcohol having a boiling point lower than that of the aromatic non-polar solvent.
Examples of such alcohols include alcohols having a carbon number of 4 or less. Among these, methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, and isobutanol are preferred.
These alcohols may be used alone or in combination of two or more kinds.

During the reaction, the reaction solvent may be refluxed. In the reaction to produce a benzoxazine compound, water is produced in the reaction system. Like alcohols, the water has the effect of suppressing the progress of the synthesis reaction of the benzoxazine compound due to the solvation effect. When a solvent that forms an azeotrope with water is used as the synthesis solvent, the water produced during the reaction may be distilled out of the system by azeotropy in order to efficiently proceed with the reaction. In that case, the water produced during the reaction can be distilled out by using, for example, a pressure-equipped dropping funnel with a stopcock, a Dimroth condenser, a Dean-Stark apparatus, or the like.

In the reaction for forming the benzoxazine ring of the benzoxazine compound of the present invention, a heating treatment is carried out during synthesis. Examples of the heating treatment method include a method in which a temperature regulator such as an oil bath is used to raise the temperature to a predetermined level and then the temperature is kept constant.
The predetermined temperature during the heating treatment is not particularly limited, but it is preferable to adjust the reaction solution temperature to 50° C. to 150° C. By setting the reaction solution temperature at 50° C. or higher, it is possible to prevent the synthesis reaction of the benzoxazine compound from slowing down and improve the synthesis efficiency. By setting the reaction solution temperature at 150° C. or lower, it is possible to suppress gelation of the reaction solution during the synthesis reaction.

The duration of the heating process is not particularly limited, but it is preferable to continue the heating for about 1 to 10 hours after the start of heating. By continuing the heating process for 1 hour or more, the synthesis reaction can be allowed to proceed sufficiently and the synthesis yield can be improved. By continuing the heating process for 10 hours or less, gelation of the reaction solution and insolubilization of the synthesized benzoxazine compound can be suppressed.

After the above heating treatment is completed, the reaction medium may be allowed to cool by being released from contact with a temperature regulator such as an oil bath, or may be cooled using a refrigerant or the like.
After cooling, the benzoxazine compound can be extracted from the reaction solution by, for example, poor solvent reprecipitation, concentration and solidification (solvent distillation under reduced pressure), spray drying, or the like.

The present invention also includes a curable resin composition containing the benzoxazine compound of the present invention.
The curable resin composition of the present invention contains the benzoxazine compound of the present invention, and thus has excellent flexibility before curing and excellent dielectric properties after curing.
The curable resin composition of the present invention is preferably a curable resin composition containing a curable resin, a curing agent, and the benzoxazine compound of the present invention.

The preferred lower limit of the content of the benzoxazine compound of the present invention in a total of 100 parts by weight of the curable resin, the curing agent, and the benzoxazine compound of the present invention is 5 parts by weight, and the preferred upper limit is 80 parts by weight. When the content of the benzoxazine compound of the present invention is within this range, the obtained curable resin composition has superior flexibility before curing and dielectric properties after curing. The more preferred lower limit of the content of the benzoxazine compound of the present invention is 10 parts by weight, and the more preferred upper limit is 60 parts by weight.

The curable resin composition of the present invention may contain, in addition to the benzoxazine compound of the present invention, other benzoxazine compounds other than the benzoxazine compound of the present invention, within the scope that does not impair the object of the present invention.

The above-mentioned curable resins include epoxy resins, cyanate resins, phenolic resins, imide resins, maleimide resins, silicone resins, acrylic resins, fluororesins, etc. Among them, the above-mentioned curable resins preferably contain at least one selected from the group consisting of epoxy resins, cyanate resins, phenolic resins, imide resins, and maleimide resins, and more preferably contain epoxy resins. The above-mentioned curable resins may be used alone or in combination of two or more.

Examples of the epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol E type epoxy resins, bisphenol S type epoxy resins, 2,2'-diallyl bisphenol A type epoxy resins, hydrogenated bisphenol type epoxy resins, propylene oxide-added bisphenol A type epoxy resins, resorcinol type epoxy resins, biphenyl type epoxy resins, sulfide type epoxy resins, diphenyl ether type epoxy resins, dicyclopentadiene type epoxy resins, naphthalene type epoxy resins, fluorene type epoxy resins, naphthylene ether type epoxy resins, phenol novolac type epoxy resins, orthocresol novolac type epoxy resins, dicyclopentadiene novolac type epoxy resins, biphenyl novolac type epoxy resins, naphthalene phenol novolac type epoxy resins, glycidyl amine type epoxy resins, alkyl polyol type epoxy resins, rubber modified epoxy resins, glycidyl ester compounds, and the like.

Examples of the curing agent include phenol-based curing agents, thiol-based curing agents, amine-based curing agents, acid anhydride-based curing agents, cyanate-based curing agents, and active ester-based curing agents. Of these, phenol-based curing agents and active ester-based curing agents are preferred.

The preferred lower limit of the content of the curing agent in a total of 100 parts by weight of the curable resin, the curing agent, and the benzoxazine compound of the present invention is 5 parts by weight, and the preferred upper limit is 80 parts by weight. When the content of the curing agent is within this range, the obtained curable resin composition has better curability and storage stability. The more preferred lower limit of the content of the curing agent is 10 parts by weight, and the more preferred upper limit is 60 parts by weight.

The curable resin composition of the present invention preferably contains a curing accelerator. By containing the above-mentioned curing accelerator, the curing time can be shortened and productivity can be improved.

Examples of the curing accelerator include imidazole-based curing accelerators, tertiary amine-based curing accelerators, phosphine-based curing accelerators, photobase generators, sulfonium salt-based curing accelerators, etc. Among these, imidazole-based curing accelerators are preferred from the viewpoints of curability and storage stability.
The above curing accelerators may be used alone or in combination of two or more kinds.

The preferred lower limit of the content of the curing accelerator relative to the total of 100 parts by weight of the curable resin, the curing agent, and the benzoxazine compound of the present invention is 0.8 parts by weight. The content of the curing accelerator is 0.8 parts by weight or more, and the effect of shortening the curing time is more excellent. The more preferred lower limit of the content of the curing accelerator is 1 part by weight.
From the viewpoint of adhesion and the like, the upper limit of the content of the curing accelerator is preferably 10 parts by weight, and more preferably 5 parts by weight.

The curable resin composition of the present invention preferably contains an inorganic filler.
By containing the inorganic filler, the curable resin composition of the present invention becomes more excellent in moisture absorption reflow resistance and plating resistance while maintaining excellent adhesive properties and the like.

The inorganic filler is preferably at least one of silica and barium sulfate. By containing at least one of silica and barium sulfate as the inorganic filler, the curable resin composition of the present invention has even better moisture absorption reflow resistance and plating resistance.

Other inorganic fillers besides the above-mentioned silica and barium sulfate include, for example, alumina, aluminum nitride, boron nitride, silicon nitride, glass powder, glass frit, glass fiber, carbon fiber, inorganic ion exchangers, etc.

The above inorganic fillers may be used alone or in combination of two or more types.

The preferred lower limit of the average particle diameter of the inorganic filler is 50 nm, and the preferred upper limit is 4 μm. When the average particle diameter of the inorganic filler is within this range, the resulting curable resin composition has better coatability. The more preferred lower limit of the average particle diameter of the inorganic filler is 100 nm, and the more preferred upper limit is 3 μm.

The preferred lower limit of the content of the inorganic filler relative to 100 parts by weight of the total of the curable resin, the curing agent, and the benzoxazine compound of the present invention is 50 parts by weight, and the preferred upper limit is 500 parts by weight. When the content of the inorganic filler is within this range, the obtained curable resin composition has better moisture absorption reflow resistance and plating resistance. A more preferred lower limit of the content of the inorganic filler is 100 parts by weight.

The curable resin composition of the present invention may contain a flow control agent for the purposes of improving the coatability onto an adherend in a short period of time and the shape retention.
Examples of the flow regulator include fumed silica such as Aerosil, layered silicates, and the like.
The flow control agents may be used alone or in combination of two or more kinds.
The flow control agent preferably has an average particle size of less than 100 nm.

The preferred lower limit of the content of the flow regulator relative to 100 parts by weight of the total of the curable resin, the curing agent, and the benzoxazine compound of the present invention is 0.1 parts by weight, and the preferred upper limit is 50 parts by weight. By having the content of the flow regulator within this range, the effect of improving the short-term coatability and shape retention on the adherend is excellent. The more preferred lower limit of the content of the flow regulator is 0.5 parts by weight, and the more preferred upper limit is 30 parts by weight.

The curable resin composition of the present invention may contain an organic filler for the purposes of stress relief, toughness, and the like.
Examples of the organic filler include silicone rubber particles, acrylic rubber particles, urethane rubber particles, polyamide particles, polyamideimide particles, polyimide particles, benzoguanamine particles, and core-shell particles thereof. Among these, polyamide particles, polyamideimide particles, and polyimide particles are preferred.
The organic fillers may be used alone or in combination of two or more kinds.

The preferred upper limit of the content of the organic filler relative to 100 parts by weight of the total of the curable resin, the curing agent, and the benzoxazine compound of the present invention is 300 parts by weight. By having the content of the organic filler be 300 parts by weight or less, the cured product of the obtained curable resin composition will have excellent toughness, etc., while maintaining excellent adhesion, etc. A more preferred upper limit of the content of the organic filler is 200 parts by weight.

The curable resin composition of the present invention may contain a flame retardant.
Examples of the flame retardant include boehmite-type aluminum hydroxide, metal hydrates such as aluminum hydroxide and magnesium hydroxide, halogen-based compounds, phosphorus-based compounds, nitrogen compounds, etc. Among these, boehmite-type aluminum hydroxide is preferred.
The flame retardants may be used alone or in combination of two or more kinds.

The preferred lower limit of the content of the flame retardant relative to 100 parts by weight of the total of the curable resin, the curing agent, and the benzoxazine compound of the present invention is 5 parts by weight, and the preferred upper limit is 200 parts by weight. By having the content of the flame retardant within this range, the obtained curable resin composition has excellent flame retardancy while maintaining excellent adhesion, etc. A more preferred lower limit of the content of the flame retardant is 10 parts by weight, and a more preferred upper limit is 150 parts by weight.

The curable resin composition of the present invention may contain a thermoplastic resin to the extent that the object of the present invention is not impaired. By using the above-mentioned thermoplastic resin, the curable resin composition of the present invention has excellent flow properties, and it becomes easier to achieve both filling properties and exudation prevention properties during thermocompression bonding, and has excellent flex resistance after curing.

Examples of the thermoplastic resin include polyimide resin, phenoxy resin, polyamide resin, polyamideimide resin, polyvinyl acetal resin, etc. Among these, phenoxy resin is preferred from the viewpoints of heat resistance and handling properties.
The above thermoplastic resins may be used alone or in combination of two or more kinds.

The preferred lower limit of the number average molecular weight of the thermoplastic resin is 3,000, and the preferred upper limit is 100,000. When the number average molecular weight of the thermoplastic resin is within this range, the resulting curable resin composition has superior flow characteristics and bending resistance after curing. The more preferred lower limit of the number average molecular weight of the thermoplastic resin is 5,000, and the more preferred upper limit is 50,000.

The preferred lower limit of the content of the thermoplastic resin relative to 100 parts by weight of the total of the curable resin, the curing agent, and the benzoxazine compound of the present invention is 2 parts by weight, and the preferred upper limit is 60 parts by weight. When the content of the thermoplastic resin is 2 parts by weight or more, the obtained curable resin composition has better flow properties and bending resistance after curing. When the content of the thermoplastic resin is 60 parts by weight or less, the obtained curable resin composition has better adhesion and heat resistance. The more preferred lower limit of the content of the thermoplastic resin is 3 parts by weight, and the more preferred upper limit is 50 parts by weight.

The curable resin composition of the present invention may contain a solvent from the viewpoint of coatability and the like.
From the viewpoints of coatability, storage stability, and the like, the above-mentioned solvent is preferably a nonpolar solvent having a boiling point of 160° C. or less, or an aprotic polar solvent having a boiling point of 160° C. or less.
Examples of the nonpolar solvents having a boiling point of 160° C. or lower or the aprotic polar solvents having a boiling point of 160° C. or lower include ketone solvents, ester solvents, hydrocarbon solvents, halogen solvents, ether solvents, and nitrogen-containing solvents.
Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.
Examples of the ester solvent include methyl acetate, ethyl acetate, and isobutyl acetate.
Examples of the hydrocarbon solvent include benzene, toluene, normal hexane, isohexane, cyclohexane, methylcyclohexane, normal heptane, and the like.
Examples of the halogen-based solvent include dichloromethane, chloroform, and trichloroethylene.
Examples of the ether solvent include diethyl ether, tetrahydrofuran, 1,4-dioxane, and 1,3-dioxolane.
The nitrogen-containing solvent includes, for example, acetonitrile.
Among these, from the viewpoints of ease of handling, solubility of the curing agent, etc., at least one solvent selected from the group consisting of ketone solvents having a boiling point of 60° C. or higher, ester solvents having a boiling point of 60° C. or higher, and ether solvents having a boiling point of 60° C. or higher is preferred. Examples of such solvents include methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, ethyl acetate, isobutyl acetate, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, etc.
The above "boiling point" means a value measured under a condition of 101 kPa, or a value converted to 101 kPa using a boiling point conversion chart or the like.

The preferred lower limit of the content of the above solvent in the curable resin composition of the present invention is 15% by weight, and the preferred upper limit is 80% by weight. When the content of the above solvent is within this range, the curable resin composition of the present invention has superior coatability, etc. A more preferred lower limit of the content of the above solvent is 20% by weight, and a more preferred upper limit is 70% by weight.

The curable resin composition of the present invention may contain a reactive diluent within a range that does not impair the object of the present invention.
From the viewpoint of adhesive reliability, the reactive diluent is preferably one having two or more reactive functional groups in one molecule.

The curable resin composition of the present invention may further contain additives such as coupling agents, dispersants, storage stabilizers, bleed inhibitors, flux agents, and leveling agents.

A method for producing the curable resin composition of the present invention includes, for example, a method in which a mixer such as a homodisper, a universal mixer, a Banbury mixer, or a kneader is used to mix a curable resin, a curing agent, the benzoxazine compound of the present invention, and a solvent or the like that is added as necessary.

The curable resin composition of the present invention can be applied onto a substrate film and dried to obtain a curable resin composition film made of the curable resin composition of the present invention, and the curable resin composition film can be cured to obtain a cured product.
A cured product obtained by curing the curable resin composition of the present invention also constitutes the present invention.

The curable resin composition of the present invention has a preferred upper limit of the dielectric loss tangent at 23° C. of 0.0045. Since the dielectric loss tangent at 23° C. of the cured product is within this range, the curable resin composition of the present invention can be suitably used as an interlayer insulating material for multilayer printed wiring boards, etc. The more preferred upper limit of the dielectric loss tangent at 23° C. of the cured product is 0.0040, and the even more preferred upper limit is 0.0035.
The "dielectric loss tangent" is a value measured at 1.0 GHz using a dielectric constant measuring device and a network analyzer. The cured product for measuring the "dielectric loss tangent" can be obtained by heating the curable resin composition film having a thickness of 40 to 200 μm at 190° C. for 90 minutes.

The curable resin composition of the present invention can be used in a wide range of applications, such as adhesives for printed wiring boards, coverlay adhesives for flexible printed circuit boards, copper-clad laminates, semiconductor bonding adhesives, interlayer insulating materials, prepregs, LED sealants, and adhesives for structural materials.
In particular, the curable resin composition of the present invention is preferably used as an adhesive. An adhesive containing the curable resin composition of the present invention also constitutes the present invention.

The curable resin film can be suitably used as an adhesive film. An adhesive film obtained by using the curable resin composition of the present invention also constitutes the present invention.
A circuit board having the cured product of the present invention also constitutes the present invention.

The curable resin composition of the present invention has a low dielectric constant, a low dielectric tangent, and excellent dielectric properties when cured, and therefore can be suitably used as an interlayer insulating material for multilayer printed wiring boards, etc. An interlayer insulating material using the curable resin composition of the present invention is also one aspect of the present invention.
The present invention also provides a multilayer printed wiring board having a circuit board, a plurality of insulating layers arranged on the circuit board, and a metal layer arranged between the plurality of insulating layers, the insulating layers being made of a cured product of the interlayer insulating material of the present invention.

According to the present invention, it is possible to provide a benzoxazine compound that can be used in a curable resin composition that has excellent flexibility before curing and excellent dielectric properties after curing. According to the present invention, it is also possible to provide a curable resin composition containing the benzoxazine compound, and an adhesive, an adhesive film, a cured product, a circuit board, an interlayer insulating material, and a multilayer printed wiring board made using the curable resin composition.

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

(Synthesis Example 1 (Preparation of benzoxazine compound A))
In a 500 mL flask equipped with a reflux tube, a pressure equalizing dropping funnel with a cock, and a Dimroth condenser, 150 mL of toluene and 50 mL of methanol were added as a mixed solvent at 25 ° C. in a lump and mixed. Next, 18.8 g (0.2 mol) of phenol (manufactured by Tokyo Chemical Industry Co., Ltd.) and 56.2 g (0.1 mol) of hydrogenated dimer diamine Priamine 1074 (manufactured by Croda) were added in a lump and mixed in the flask at 25 ° C. Then, 13.2 g (0.44 mol) of paraformaldehyde (manufactured by Tokyo Chemical Industry Co., Ltd.) was added in a lump and mixed in the flask at 25 ° C. to obtain a mixed solution.
The flask containing the obtained mixed solution was immersed in an oil bath set at 120° C., and the reaction was allowed to proceed by heating while refluxing. One hour after the start of reflux, water produced in the reaction system was distilled out of the system by azeotropy with toluene and methanol.
After the reaction was allowed to proceed for 4 hours from the start of distillation, the flask was removed from the oil bath and the resulting reaction solution was cooled to 25° C. After cooling, the reaction solution was poured into 1 L of methanol to precipitate the reactant. The precipitated solid was dried under reduced pressure to obtain benzoxazine compound A.
It was confirmed by ¹ H-NMR, GPC, and FT-IR analyses that benzoxazine compound A contained a benzoxazine compound having a structure represented by formula (1-1) (A is a hydrogenated dimer diamine residue, and X and X′ are hydrogen atoms). The number average molecular weight of benzoxazine compound A was 800.

(Synthesis Example 2 (Preparation of benzoxazine compound B))
A benzoxazine compound B was obtained in the same manner as in Synthesis Example 1, except that 56.8 g (0.1 mol) of Priamin 1073 (manufactured by Croda), which is a dimer diamine, was used instead of Priamin 1074.
It was confirmed by ¹ H-NMR, GPC, and FT-IR analyses that benzoxazine compound B contained a benzoxazine compound having a structure represented by formula (1-1) (A is a dimer diamine residue, and X and X′ are hydrogen atoms). The number average molecular weight of benzoxazine compound B was 800.

(Synthesis Example 3 (Preparation of benzoxazine compound C))
A benzoxazine compound C was obtained in the same manner as in Synthesis Example 1, except that Priamine 1074 was replaced with 61.7 g (0.1 mol) of Priamine 1071 (manufactured by Croda), which is a mixture of dimer diamine and trimer triamine.
It was confirmed by ¹ H-NMR, GPC, and FT-IR analyses that benzoxazine compound C contained a benzoxazine compound having a structure represented by formula (1-1) above (A is a dimer triamine residue, and X and X' are hydrogen atoms). It was also confirmed that benzoxazine compound C contained a benzoxazine compound having a structure represented by formula (1-2) above (A is a trimer triamine residue, and X, X', and X'' are hydrogen atoms). The number average molecular weight of benzoxazine compound C was 850.

(Synthesis Example 4 (Preparation of benzoxazine compound D))
56.8 g (0.1 mol) of Priamine 1073 (manufactured by Croda), which is a dimer diamine, was dissolved in 400 g of N-methylpyrrolidone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., "NMP"). 104.1 g (0.2 mol) of 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.) was added as an aromatic tetracarboxylic acid to the obtained solution, and the mixture was stirred at 25°C for 2 hours to react, thereby obtaining an amic acid oligomer solution. N-methylpyrrolidone was removed from the obtained amic acid oligomer solution under reduced pressure, and the solution was heated at 300°C for 2 hours to obtain an imide oligomer having acid anhydride groups at both ends.
26.8 g (0.2 mol) of 3-aminophenol (Tokyo Chemical Industry Co., Ltd.) was dissolved in 400 g of N-methylpyrrolidone (FUJIFILM Wako Pure Chemical Industries, Ltd., "NMP"). 157.3 g (0.1 mol) of imide oligomer having acid anhydride groups at both ends was added to the obtained solution, and the mixture was stirred at 25°C for 2 hours to react, thereby obtaining an amic acid oligomer solution. N-methylpyrrolidone was removed from the obtained amic acid oligomer solution under reduced pressure, and the solution was heated at 300°C for 2 hours to obtain an imide oligomer having phenolic hydroxyl groups at both ends.
In a 500 mL flask equipped with a reflux tube, a pressure equalizing dropping funnel with a cock, and a Dimroth condenser, 150 mL of toluene and 50 mL of methanol were added as a mixed solvent at 25° C. in a lump. Next, 174.7 g (0.1 mol) of an imide oligomer having phenolic hydroxyl groups at both ends and 18.6 g (0.2 mol) of aniline (manufactured by Tokyo Chemical Industry Co., Ltd.) were added in a lump at 25° C. and mixed in the flask. Then, 13.2 g (0.44 mol) of paraformaldehyde (manufactured by Tokyo Chemical Industry Co., Ltd.) were added in a lump at 25° C. and mixed in the flask to obtain a mixed solution.
The flask containing the obtained mixed solution was immersed in an oil bath set at 120° C., and the reaction was allowed to proceed by heating while refluxing. One hour after the start of reflux, water produced in the reaction system was distilled out of the system by azeotropy with toluene and methanol.
After the reaction was allowed to proceed for 4 hours from the start of distillation, the flask was removed from the oil bath and the resulting reaction solution was cooled to 25° C. After cooling, the reaction solution was poured into 1 L of methanol to precipitate the reactant. The precipitated solid was dried under reduced pressure to obtain benzoxazine compound D.
It was confirmed by ¹ H-NMR, GPC, and FT-IR analyses that benzoxazine compound D contained a benzoxazine compound having a structure represented by formula (4) above (A is a dimer diamine residue, C and C' are 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride residues, and Y and Y' are phenyl groups). The number average molecular weight of benzoxazine compound D was 2000.

(Synthesis Example 5 (Preparation of benzoxazine compound E))
113.6 g (0.2 mol) of Priamine 1073 (manufactured by Croda), which is a dimer diamine, was dissolved in 400 g of N-methylpyrrolidone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., "NMP"). 52.0 g (0.1 mol) of 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.) was added as an aromatic tetracarboxylic acid to the obtained solution, and the mixture was stirred at 25°C for 2 hours to react, thereby obtaining an amic acid oligomer solution. N-methylpyrrolidone was removed from the obtained amic acid oligomer solution under reduced pressure, and the solution was heated at 300°C for 2 hours to obtain an imide oligomer having amino groups at both ends.
In a 500 mL flask equipped with a reflux tube, a pressure equalizing dropping funnel with a cock, and a Dimroth condenser, 150 mL of toluene and 50 mL of methanol were added as a mixed solvent at 25° C. in a lump and mixed. Next, 18.8 g (0.2 mol) of phenol (manufactured by Tokyo Chemical Industry Co., Ltd.) and 160.7 g (0.1 mol) of the obtained imide oligomer having amino groups at both ends were added in a lump and mixed in the flask at 25° C. Then, 13.2 g (0.44 mol) of paraformaldehyde (manufactured by Tokyo Chemical Industry Co., Ltd.) was added in a lump and mixed in the flask at 25° C. to obtain a mixed solution.
The flask containing the obtained mixed solution was immersed in an oil bath set at 120° C., and the reaction was allowed to proceed by heating while refluxing. One hour after the start of reflux, water produced in the reaction system was distilled out of the system by azeotropy with toluene and methanol.
After the reaction was allowed to proceed for 4 hours from the start of distillation, the flask was removed from the oil bath and the resulting reaction solution was cooled to 25° C. After cooling, the reaction solution was poured into 1 L of methanol to precipitate the reactant. The precipitated solid was dried under reduced pressure to obtain benzoxazine compound E.
It was confirmed by ¹ H-NMR, GPC, and FT-IR analyses that benzoxazine compound E contained a benzoxazine compound having a structure represented by formula (5) above. In benzoxazine compound E, A and A' in formula (5) above were imide oligomer residues having amino groups at both ends, C was a 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride residue, and X and X' were hydrogen atoms. The number average molecular weight of benzoxazine compound E was 1960.

(Synthesis Example 6 (Preparation of benzoxazine compound F))
In a 500 mL flask equipped with a reflux tube, a pressure equalizing dropping funnel with a cock, and a Dimroth condenser, 150 mL of toluene and 50 mL of methanol were added as a mixed solvent all at once at 25° C. and mixed. Next, 34.7 g (0.1 mol) of 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene (Tokyo Chemical Industry Co., Ltd., "Bisphenol M") and 56.2 g (0.1 mol) of hydrogenated dimer diamine Priamine 1074 (Croda) were added all at once to the flask at 25° C. and mixed. Thereafter, 13.2 g (0.44 mol) of paraformaldehyde (Tokyo Chemical Industry Co., Ltd.) was added all at once to the flask at 25° C. and mixed to obtain a mixed solution.
The flask containing the obtained mixed solution was immersed in an oil bath set at 80° C. and heated while refluxing to allow the reaction to proceed. One hour after the start of reflux, water produced in the reaction system was distilled out of the system by azeotropy with toluene and methanol.
After the reaction was allowed to proceed for 4 hours from the start of distillation, the flask was removed from the oil bath and the resulting reaction solution was cooled to 25° C. After cooling, the reaction solution was poured into 1 L of methanol to precipitate the reactant. The precipitated solid was dried under reduced pressure to obtain benzoxazine compound F.
It was confirmed by ^1H -NMR, GPC, and FT-IR analyses that benzoxazine compound F contained a benzoxazine compound having a repeating structural unit represented by formula (6) above (A is a hydrogenated dimer diamine residue, and Z is a group represented by formula (9) below). The number average molecular weight of benzoxazine compound F was 12,000.

In formula (9), * indicates the bond position.

(Synthesis Example 7 (Preparation of benzoxazine compound G))
A benzoxazine compound G was obtained in the same manner as in Synthesis Example 1, except that 29.2 g (0.1 mol) of 1,3-bis(3-aminophenoxy)benzene (manufactured by Mitsui Fine Chemicals, Inc., "APB-N"), which is a diamine having no aliphatic skeleton having 4 or more carbon atoms, was used instead of Priamine 1074.
It was confirmed by ¹ H-NMR, GPC, and FT-IR analyses that benzoxazine compound G contained a benzoxazine compound in which the moiety corresponding to A in formula (1-1) was a 1,3-bis(3-aminophenoxy)benzene residue and the moieties corresponding to X and X' were hydrogen atoms. The number average molecular weight of benzoxazine compound G was 600.

(Examples 1 to 7, Comparative Examples 1 and 2)
Methyl ethyl ketone was added as a solvent to each material having the compounding ratio shown in Table 1, and the mixture was stirred at 1200 rpm for 4 hours using a stirrer to obtain a curable resin composition. Note that the composition in Table 1 shows the solid content excluding the solvent.
The obtained curable resin composition was applied onto a release-treated surface of a PET film ("XG284" manufactured by Toray Industries, Inc., thickness 25 μm) using an applicator. The film was then dried for 5 minutes in a gear oven at 100° C. to volatilize the solvent, thereby obtaining an uncured laminate film having a PET film and a 40 μm-thick layer of the curable resin composition on the PET film.

<Evaluation>
The uncured laminate films obtained in the Examples and Comparative Examples were evaluated as follows. The results are shown in Table 1.

(Flexibility)
Each uncured laminate film obtained in the examples and comparative examples was cut into a rectangle of 10 cm length x 5 cm width. The film was folded 90 degrees or 180 degrees so that the PET film layer was on the inside, and then returned to a flat state, and the state of the film was visually confirmed. Note that when folded 180 degrees, the film was more likely to break than when folded 90 degrees.
Flexibility was evaluated as follows: if there was no crack when bent at both 90 degrees and 180 degrees, it was marked as "○"; if there was a crack when bent at 180 degrees and no crack when bent at 90 degrees, it was marked as "△"; if there was a crack when bent at both 90 degrees and 180 degrees, it was marked as "×".

(Dielectric Properties)
Each uncured laminate film obtained in the examples and comparative examples was cut into a size of 2 mm wide and 80 mm long. The substrate PET film was peeled off from the curable resin composition layer of the uncured laminate film after cutting, and five curable resin composition layers were laminated using a laminator to obtain a laminate with a thickness of about 200 μm. The obtained laminate was heated at 190 ° C for 90 minutes to obtain a cured body. The dielectric loss tangent of the obtained cured body was measured at 23 ° C and a frequency of 1.0 GHz by the cavity resonance method using a cavity resonance perturbation method dielectric constant measuring device CP521 (manufactured by Kanto Electronics Application Development Co., Ltd.) and a network analyzer N5224A PNA (manufactured by Keysight Technologies, Inc.).
The dielectric properties were evaluated as follows: when the dielectric tangent was 0.0035 or less, it was marked "◎"; when the dielectric tangent was more than 0.0035 and less than 0.0040, it was marked "◯"; when the dielectric tangent was more than 0.0040 and less than 0.0045, it was marked "△"; and when the dielectric tangent was more than 0.0045, it was marked "X".

(Desmearing ability (ability to remove residues at the bottom of vias))
(1) Lamination and Semi-Cure Treatment Both sides of a CCL substrate (Hitachi Chemical Co., Ltd., "E679FG") were immersed in a copper surface roughening agent (Mec Corporation, "Mec Etch Bond CZ-8100") to roughen the copper surface. Each uncured laminate film obtained in the examples and comparative examples was set on both sides of the CCL substrate from the curable resin composition layer side, and laminated on both sides of the CCL substrate using a diaphragm type vacuum laminator (Meiki Seisakusho Co., Ltd., "MVLP-500") to obtain an uncured laminate sample A. Lamination was performed by reducing the pressure for 20 seconds to 13 hPa or less, and then pressing at 100°C and a pressure of 0.8 MPa for 20 seconds.
The substrate PET film was peeled off from the obtained uncured laminate sample A, and then the curable resin composition was cured under curing conditions of 170° C. and 30 minutes to obtain a semi-cured laminate sample.

(2) Formation of vias (through holes) Using a _CO2 laser (manufactured by Hitachi Via Mechanics), vias (through holes) having a diameter of 60 μm at the upper end and a diameter of 40 μm at the lower end (bottom) were formed in the obtained semi-cured laminate sample, thereby obtaining a laminate B in which a semi-cured product of a curable resin composition was laminated on a CCL substrate and a via (through hole) was formed in the semi-cured product of the curable resin composition.

(3) Treatment for Removing Residues from the Bottom of the Via (a) Swelling Treatment The obtained laminate B was placed in a swelling liquid (manufactured by Atotech Japan, "Swelling Dip Securigant P") at 70°C and swung for 10 minutes. Thereafter, it was washed with pure water.

(b) Permanganate treatment (roughening treatment and desmear treatment)
The laminate B after the swelling treatment was placed in a roughening aqueous solution of potassium permanganate ("Concentrate Compact CP" manufactured by Atotech Japan) at 80° C. and was shaken for 30 minutes. Next, it was treated for 2 minutes using a cleaning solution ("Reduction Securigant P" manufactured by Atotech Japan) at 25° C., and then washed with pure water to obtain evaluation sample 1.

The bottom of the via of evaluation sample 1 was observed with a scanning electron microscope (SEM), and the maximum smear length from the wall surface of the via bottom was measured.
The desmear property (removability of residue at the via bottom) was evaluated as follows: when the maximum smear length was less than 2 μm, it was marked with "◎", when the maximum smear length was 2 μm or more and less than 2.5 μm, it was marked with "◯", when the maximum smear length was 2.5 μm or more and less than 3 μm, it was marked with "△", and when the maximum smear length was 3 μm or more, it was marked with "×".

(Plating adhesion)
The semi-cured laminate sample prepared in the same manner as in "(Desmear property (removability of residue at via bottom))" above was placed in a swelling liquid (aqueous solution prepared from "Swelling Dip Securigant P" manufactured by Atotech Japan and sodium hydroxide (manufactured by Fujifilm Wako Pure Chemical Industries)) at 70°C and swung for 10 minutes. Then, it was washed with pure water.
The swelling-treated semi-cured laminate sample was placed in an aqueous solution of sodium permanganate roughening (aqueous solution prepared from "Concentrate Compact CP" manufactured by Atotech Japan and sodium hydroxide (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) at 80° C., and swung for 30 minutes. Thereafter, the sample was washed for 2 minutes with a cleaning solution (aqueous solution prepared from "Reduction Securigant P" manufactured by Atotech Japan and sulfuric acid (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.)) at 25° C., and then further washed with pure water to form a roughened semi-cured material on the CCL substrate.
The roughened surface of the semi-cured product was treated with an alkaline cleaner at 60° C. ("Cleaner Securigant 902" manufactured by Atotech Japan) for 5 minutes to degrease and clean. After cleaning, the semi-cured product was treated with a pre-dip liquid at 25° C. ("Pre-dip Neogant B" manufactured by Atotech Japan) for 2 minutes. Thereafter, the semi-cured product was treated with an activator liquid at 40° C. ("Activator Neogant 834" manufactured by Atotech Japan) for 5 minutes to apply a palladium catalyst.
Next, the semi-cured product was treated with a 30°C reducing solution ("Reducer Neoganth WA" manufactured by Atotech Japan) for 5 minutes, and then placed in a chemical copper solution ("Basic Printganth MSK-DK", "Copper Printganth MSK", "Stabilizer Printganth MSK", and "Reducer Cu" all manufactured by Atotech Japan). Electroless plating was carried out until the plating thickness reached approximately 0.5 μm. After electroless plating, annealing was carried out at a temperature of 120°C for 30 minutes to remove residual hydrogen gas. All steps up to the electroless plating step were carried out using 2 L of treatment solution on a beaker scale, while the semi-cured product was rocked.
The electrolytically plated semi-cured product was subjected to electrolytic plating. The electrolytic plating was performed using a copper sulfate solution (aqueous solution prepared from copper sulfate pentahydrate (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.), sulfuric acid (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.), "Basic Leveler Cupracid HL" manufactured by Atotech Japan, and "Correction Agent Cupracid GS" manufactured by Atotech Japan) with a current of 0.6 A/ ^cm2 until the plating thickness reached about 25 μm. After the electrolytic plating, the semi-cured product was heated at 190° C. for 90 minutes to further harden the semi-cured product, and a hardened product having a copper plating layer laminated on the upper surface was obtained.
In the cured product having the copper plating layer laminated thereon, a notch having a width of 10 mm was made in the surface of the copper plating layer, and then the adhesion strength (90° peel strength) between the cured product (insulating layer) and the metal layer (copper plating layer) was measured using a tensile tester (manufactured by Shimadzu Corporation, "AG-5000B") at a crosshead speed of 5 mm/min.
The plating adhesion was evaluated as follows: when the peel strength was 0.50 kgf/cm or more, it was marked "◎", when the peel strength was 0.45 kgf/cm or more and less than 0.50 kgf/cm, it was marked "◯", when the peel strength was 0.40 kgf/cm or more and less than 0.45 kgf/cm, it was marked "△", and when the peel strength was less than 0.40 kgf/cm, it was marked "X".

According to the present invention, it is possible to provide a benzoxazine compound that can be used in a curable resin composition that has excellent flexibility before curing and excellent dielectric properties after curing. According to the present invention, it is also possible to provide a curable resin composition containing the benzoxazine compound, and an adhesive, an adhesive film, a cured product, a circuit board, an interlayer insulating material, and a multilayer printed wiring board made using the curable resin composition.

Claims (11)

The compound has, in its molecule, a diamine residue having an aliphatic skeleton having 4 or more carbon atoms and/or a triamine residue having an aliphatic skeleton having 4 or more carbon atoms, and a benzoxazine ring,
The diamine and/or triamine from which the diamine residue and/or the triamine residue are derived is an aliphatic diamine and/or an aliphatic triamine derived from a dimer acid which is a dimer of an aliphatic acid having from 10 to 30 carbon atoms and/or a trimer acid which is a trimer of an aliphatic acid having from 10 to 30 carbon atoms ,
A benzoxazine compound having a structure represented by the following formula (1-1) or (1-2), the following formula (2-1) or (2-2), or the following formula (3).

In formula (1-1), A is the diamine residue, and X and X' are each independently a hydrogen atom or any substituent.
In formula (1-2), A is the triamine residue, and X, X', and X'' each independently represent a hydrogen atom or any substituent.

In formula (2-1), A is the diamine residue, B and B' are each independently an arbitrary organic group, R and R' are each independently a hydrogen atom or an arbitrary substituent, B and each R may be bonded to form a ring structure, B' and each R' may be bonded to form a ring structure, and Y and Y' are each independently a hydrogen atom or an arbitrary substituent.
In formula (2-2), A is the triamine residue; B, B', and B'' are each independently any organic group; R, R', and R'' are each independently a hydrogen atom or any substituent; B and each R may be bonded to form a ring structure; B' and each R may be bonded to form a ring structure; B'' and each R'' may be bonded to form a ring structure; and Y, Y', and Y'' are each independently a hydrogen atom or any substituent.

In formula (3), A and A' are each independently the diamine residue, B is an arbitrary organic group, R and R' are each independently a hydrogen atom or an arbitrary substituent, B and R may be bonded to form a ring structure, B and R' may be bonded to form a ring structure, and X and X' are each independently a hydrogen atom or an arbitrary substituent. The benzoxazine compound according to claim 1, having a repeating structural unit represented by the following formula (6), the following formula (7), or the following formula (8).

In formula (6), A is the diamine residue, and Z is a bond or an arbitrary organic group. A part or all of the hydrogen atoms in the aromatic ring in formula (6) may be substituted with an arbitrary substituent.

In formula (7), A is the diamine residue, B and B' are each independently any organic group, R and R' are each independently a hydrogen atom or any substituent, B and R may be bonded to form a ring structure, B' and R' may be bonded to form a ring structure, and W is any organic group.

In formula (8), A and A' are each independently the diamine residue, B is an arbitrary organic group, R and R' are each independently a hydrogen atom or an arbitrary substituent, B and R may be bonded to form a ring structure, B and R' may be bonded to form a ring structure, and Z is a bond or an arbitrary organic group. The hydrogen atoms of the aromatic ring in formula (8) may be partially or completely substituted with an arbitrary substituent. A curable resin composition comprising the benzoxazine compound according to claim 1 or 2 . 4. The curable resin composition according to claim 3 , which comprises a curable resin, a curing agent, and the benzoxazine compound according to claim 1. The curable resin composition according to claim 4 , wherein the curable resin comprises at least one selected from the group consisting of an epoxy resin, a cyanate resin, a phenolic resin, an imide resin, and a maleimide resin. An adhesive comprising the curable resin composition according to claim 3, 4 or 5 . An adhesive film obtained by using the curable resin composition according to claim 3, 4 or 5 . A cured product obtained by curing the curable resin composition according to claim 3, 4 or 5 . A circuit board comprising the cured product according to claim 8 . An interlayer insulating material comprising the curable resin composition according to claim 3, 4 or 5 . 11. A multilayer printed wiring board comprising a circuit board, a plurality of insulating layers disposed on the circuit board, and a metal layer disposed between the plurality of insulating layers, the insulating layers being made of a cured product of the interlayer insulating material according to claim 10 .