Method for producing maleimide resin

Abstract

A method for producing a maleimide resin that is obtained by reacting a tetracarboxylic dianhydride (a1), an amine (a2), and a maleic anhydride (a3), the method comprising: a step for adding the amine (a2) to the tetracarboxylic dianhydride (a1) in the presence of an organic solvent so as to obtain a polyimide resin; and a step for adding the maleic anhydride (a3) to the polyimide resin so as to obtain a maleimide resin, wherein the organic solvent contains at least one of γ-butyrolactone and N-ethyl-2-pyrrolidone, and the amine (a2) contains a dimer diamine and a second amine other than the dimer diamine.

Description

Manufacturing method for maleimide resin

[0001] The present disclosure relates to a method for producing maleimide resins.

[0002] Printed wiring boards and multilayer wiring boards using them are used in products such as mobile communication devices such as mobile phones and smartphones, their base station equipment, network-related electronic devices such as servers and routers, and large computers.

[0003] In recent years, these products have used high-frequency electrical signals to transmit and process large amounts of information at high speed. However, high-frequency signals are highly susceptible to attenuation, and therefore, in order to reduce transmission loss, insulating materials with excellent dielectric properties are required as insulating materials used in the above-mentioned printed wiring boards, multilayer wiring boards, and the like.

[0004] Epoxy resin compositions disclosed in Patent Documents 1 to 3 are known as the insulating material. Patent Document 1 discloses that an epoxy resin composition containing an epoxy resin, an active ester compound, and a triazine-containing cresol novolac resin is effective in reducing dielectric loss tangent. Patent Documents 2 and 3 disclose that resin compositions containing an epoxy resin and an active ester compound as essential components can form cured products with low dielectric loss tangent and are useful as insulating materials. However, it has been found that these epoxy resin compositions are unsatisfactory for high-frequency band applications.

[0005] On the other hand, Patent Document 4 reports that a resin film made of a resin composition containing a bismaleimide resin having a long-chain alkyl group as a non-epoxy material and a curing agent has excellent dielectric properties (low relative dielectric constant and low dielectric loss tangent). However, bismaleimide resins made only of long-chain alkyldiamines have problems such as low Tg and low elastic modulus.

[0006] JP 2011-132507 A JP 2015-101626 A JP 2017-210527 A WO 2016 / 114287

[0007] The present inventors have been investigating maleimide resins obtainable by using dimer diamine and other amines as the amine, as maleimide resins capable of forming cured products having a high elastic modulus and a high Tg while sufficiently maintaining a low dielectric constant and a low dielectric dissipation factor.

[0008] An object of the present disclosure is to provide a novel production method for producing a specific maleimide resin, and in particular, to provide a production method for producing a maleimide resin that can provide a resin composition with good storage stability.

[0009] In order to achieve the above object, the present disclosure provides the following methods for producing a maleimide resin: [1] A method for producing a maleimide resin obtained by reacting a tetracarboxylic dianhydride (a1), an amine (a2), and maleic anhydride (a3), the method comprising the steps of adding the amine (a2) to the tetracarboxylic dianhydride (a1) in the presence of an organic solvent to obtain a polyimide resin, and adding the maleic anhydride (a3) ​​to the polyimide resin to obtain the maleimide resin, wherein the organic solvent contains at least one of γ-butyrolactone and N-ethyl-2-pyrrolidone, and the amine (a2) contains dimerdiamine and a second amine other than dimerdiamine. [2] The method for producing a maleimide resin according to [1] above, wherein at least one of the tetracarboxylic dianhydride (a1) and the amine (a2) contains a compound having a fluorene skeleton. [3] The method for producing a maleimide resin according to [1] or [2] above, wherein the tetracarboxylic dianhydride (a1) comprises at least one of 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)naphtho[1,2-c]furan-1,3-dione, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride, and 3,3',4,4'-biphenyltetracarboxylic dianhydride. [4] The method for producing a maleimide resin according to any one of [1] to [3] above, wherein the second amine comprises at least one of norbornanediamine, 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene, and 9,9-bis(4-aminophenyl)fluorene. [5] The method for producing a maleimide resin according to any one of [1] to [4] above, wherein the dimer diamine contains at least one of a compound represented by the following general formula (1) and a compound represented by the following general formula (2): [In formulas (1) and (2), m, n, p, and q each represent an integer of 1 or greater selected so that m+n=6 to 17 and p+q=8 to 19, and the bond indicated by a dashed line represents a carbon-carbon single bond or a carbon-carbon double bond. However, when the bond indicated by a dashed line is a carbon-carbon double bond, formulas (1) and (2) have a structure in which the number of hydrogen atoms bonded to each carbon atom constituting the carbon-carbon double bond is subtracted by one from the number indicated in formulas (1) and (2).] [6] A method for producing a maleimide resin according to any one of [1] to [5] above, which is obtained by reacting 1.00 mol of the amine (a2) with 0.30 to 1.00 mol of the tetracarboxylic dianhydride (a1). [7] A method for producing a maleimide resin according to any one of [1] to [6] above, wherein the organic solvent further contains an aromatic hydrocarbon having a boiling point of 150°C or higher. [8] The method for producing a maleimide resin according to any one of [1] to [7] above, wherein the organic solvent further contains an alcohol having a boiling point of 100° C. or less. [9] The method for producing a maleimide resin according to any one of [1] to [8] above, wherein the content of the γ-butyrolactone and N-ethyl-2-pyrrolidone in the organic solvent is 5 to 40 mass % based on the total amount of the organic solvent.

[0010] The present disclosure provides a novel production method for producing a specific maleimide resin. In particular, the present disclosure provides a production method for producing a maleimide resin that can improve the storage stability of a resin composition. Furthermore, maleimide resins produced by the maleimide resin production method of the present disclosure, and resin compositions (adhesive compositions) using the same, can reduce both the dielectric constant and dielectric loss tangent (hereinafter, both may be collectively referred to as "dielectric properties"), and are capable of forming cured products that have excellent low dielectric properties, particularly in the high frequency band, and have a high modulus of elasticity and a high Tg. Because the cured products (adhesive layers) obtained from the resin compositions have a high modulus of elasticity and a high Tg, the resin compositions are useful not only as adhesives used in the production of printed circuit boards (build-up boards, flexible printed wiring boards, etc.) and copper-clad boards for printed wiring boards, but also as insulating films such as rewiring layers, semiconductor interlayer materials, coating agents, resist inks, conductive pastes, and the like.

[0011] 1 shows an IR spectrum of maleimide resin (A-1) synthesized in Example 1. FIG. 2 shows an IR spectrum of maleimide resin (A-2) synthesized in Example 2.

[0012] Preferred embodiments of the present disclosure will be described in detail below. However, the present disclosure is not limited to the following embodiments and can be implemented in various modifications within the scope of the present disclosure.

[0013] In this specification, numerical ranges indicated using "to" indicate ranges that include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of another numerical range. In the numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with a value shown in the examples. "A or B" may include either A or B, or may include both. Unless otherwise specified, the materials exemplified in this specification can be used alone or in combination of two or more. When multiple substances corresponding to each component are present in the composition, the content of each component in the composition refers to the total amount of the multiple substances present in the composition, unless otherwise specified. In this specification, "solid content" refers to the non-volatile content of the resin composition excluding volatile substances (water, solvent, etc.), and also includes components that are liquid, syrup-like, or waxy at room temperature (around 25°C).

[0014] <Method for Producing Maleimide Resin> The method for producing a maleimide resin according to the present embodiment is a method for producing a maleimide resin obtained by reacting a tetracarboxylic dianhydride (a1) (hereinafter also referred to as "component (a1)"), an amine (a2) (hereinafter also referred to as "component (a2)"), and maleic anhydride (a3) ​​(hereinafter also referred to as "component (a3)"), and includes the steps of adding the amine (a2) to the tetracarboxylic dianhydride (a1) in the presence of an organic solvent to obtain a polyimide resin, and adding the maleic anhydride (a3) ​​to the polyimide resin to obtain a maleimide resin. Here, the organic solvent contains at least one of γ-butyrolactone and N-ethyl-2-pyrrolidone. The amine (a2) contains dimer diamine and a second amine other than dimer diamine.

[0015] (Component (a1): Tetracarboxylic acid dianhydride) As the tetracarboxylic acid dianhydride of the component (a1), any known material for polyimide can be used. Examples of the component (a1) include pyromellitic anhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)naphtho[1,2-c]furan-1,3-dione, 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic acid dianhydride, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 3,3',4,4'-diphenylsulfone ... ,3',4,4'-benzophenonetetracarboxylic dianhydride, 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, bicyclo[2.2.2]oct-7-ene -2,3,5,6-tetracarboxylic dianhydride, bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid) 1,4-phenylene, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 4,4'-(ethyn-1,2-diyl)diphthalic anhydride, 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, dicyclohexyl-3,4,3',4'-tetracarboxylic acid Examples of suitable phthalic anhydrides include phthalic dianhydride, 3,4'-oxydiphthalic anhydride, 3,4'-biphthalic anhydride, norbornane-2-spiro-α-cyclopentanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic dianhydride, 5,5'-bis-2-norbornene-5,5',6,6'-tetracarboxylic-5,5',6,6'-dianhydride, and 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride. These may be used alone or in combination of two or more.

[0016] From the viewpoint of low dielectric properties, high Tg, or low coefficient of linear expansion (CTE), the component (a1) is preferably selected from the group consisting of 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)naphtho[1,2-c]furan-1,3-dione, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 5-(2,5-dioxo-3-furanyl ... at least one selected from the group consisting of dicyclohexyl-3,4,3',4'-tetracarboxylic acid dianhydride, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic acid 2,3:5,6-dianhydride, 5,5'-bis-2-norbornene-5,5',6,6'-tetracarboxylic acid-5,5',6,6'-dianhydride, 3,4'-biphthalic anhydride, and 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride; Preferably, the compound contains at least one of 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)naphtho[1,2-c]furan-1,3-dione, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride, and 3,3',4,4'-biphenyl. It is more preferable that the compound contains at least one selected from the group consisting of tetracarboxylic acid dianhydrides, and it is even more preferable that the compound contains at least one selected from the group consisting of 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)naphtho[1,2-c]furan-1,3-dione, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride, and 3,3',4,4'-biphenyltetracarboxylic acid dianhydride.

[0017] The component (a2) contains a dimer diamine (first amine) and a second amine other than the dimer diamine.

[0018] Dimer diamine is a compound derived from dimer acid, which is a dimer of unsaturated fatty acids such as oleic acid, as described in, for example, JP-A-9-12712. By using dimer diamine as component (a2), the dielectric properties of the cured product can be reduced. In this embodiment, any known dimer diamine can be used without particular limitations. The dimer diamine preferably includes, for example, at least one of a compound represented by the following general formula (1) and a compound represented by the following general formula (2):

[0019] [In formulas (1) and (2), m, n, p, and q each represent an integer of 1 or greater selected so that m+n=6 to 17 and p+q=8 to 19, and the bond shown by a dashed line represents a carbon-carbon single bond or a carbon-carbon double bond. However, when the bond shown by a dashed line is a carbon-carbon double bond, formulas (1) and (2) have a structure in which the number of hydrogen atoms bonded to each carbon atom constituting the carbon-carbon double bond is reduced by one from the number shown in formulas (1) and (2)]

[0020] The dimer diamine may be one represented by the above general formula (2), particularly a compound represented by the following formula (3), from the viewpoints of solubility in organic solvents, heat resistance, heat-resistant adhesion, low viscosity, etc.

[0021] Commercially available dimer diamines include, for example, PRIAMINE 1075 and PRIAMINE 1074 (both manufactured by Croda Japan Co., Ltd.), which may be used singly or in combination of two or more.

[0022] The second amine is an amine other than the above-mentioned dimer diamine. The second amine may be a diamine or triamine, or may be a diamine. By using an alicyclic diamine as the second amine, the dielectric constant can be further reduced. By using an aromatic diamine as the second amine, the elastic modulus, Tg, and CTE of the cured product can be improved.

[0023] When the second amine is a diamine, examples of the diamine include 1,3-diaminopropane, norbornanediamine, 4,4'-methylenedianiline, 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene, 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 9,9-bis(4-aminophenyl)fluorene, 9,9-bis[3-fluoro-4-aminophenyl]fluorene, 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, bis(aminomethyl)norbornane, 4,4'-(hexafluoroisopropylidene)dianiline, 3(4),8(9)-bis(aminomethyl)tricyclo[5.2.1.0 ２，６]decane, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, isophoronediamine, 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(2-methylcyclohexylamine), 1,1-bis(4-aminophenyl)cyclohexane, 2,7-diaminofluorene, 4,4'-ethylenedianiline, 4,4'-methylenebis(2,6-diethylaniline), 4,4'-methylenebis(2-ethyl-6-methylaniline), 2,2-bis[4-(4-aminophenoxy)phenyl]propane, bis[4-(4-aminophenoxy)phenyl]methane, 4,4'-bis(4-aminophenoxy)biphenyl bis[4-(4-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ketone, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 2,2'-dimethylbiphenyl-4,4'-diamine, (4,4'-diamino)diphenyl ether, (3,3'-diamino)diphenyl ether, paraphenylenediamine, orthophenylenediamine, metaphenylenediamine, 2,2'-dimethylbiphenyl-4,4'-diamine, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, etc. These may be used alone or in combination of two or more.

[0024] When the second amine is a triamine, examples of the triamine include tris(aminomethyl)amine, tris(2-aminoethyl)amine, tris(2-aminopropyl)amine, 2-(aminomethyl)-2-methyl-1,3-propanediamine, trimer triamine, 3,4,4'-triaminodiphenyl ether, 1,2,4-triaminobenzene, 1,3,5-triaminobenzene, 1,2,3-triaminobenzene, 1,3,5-triazine-2,4,6-triamine, 2,4,6-triaminopyrimidine, 1,3,5-tris(4-aminophenyl)benzene, 1,3,5-tris(4-aminophenoxy)benzene, etc. These may be used alone or in combination of two or more. Among these, aliphatic triamines are preferred from the viewpoint of the solubility of the synthesized maleimide resin in organic solvents, and tris(aminomethyl)amine and tris(2-aminoethyl)amine, which have a small number of carbon atoms, are more preferred from the viewpoint of achieving a high Tg.

[0025] The second amine may include one or both of the above-mentioned diamines and triamines, or may include an amine other than the diamines and triamines.

[0026] From the viewpoints of high Tg, high elastic modulus, and low CTE, the second amine preferably contains at least one of norbornanediamine, 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene, and 9,9-bis(4-aminophenyl)fluorene.

[0027] In component (a2), the molar ratio of the second amine to the total amount of amines (moles of second amine / (moles of dimer diamine+moles of second amine)) may be 70 mol% or less, or may be 50 mol% or less. When this ratio is 70 mol% or less, the dielectric properties of the cured product can be further reduced.

[0028] When the second amine contains a diamine, the molar ratio of the diamine in the second amine to the total amount of diamine in component (a2) (number of moles of diamine in the second amine / (number of moles of dimer diamine + number of moles of diamine in the second amine)) may be 70 mol% or less, or may be 50 mol% or less. When this ratio is 70 mol% or less, the dielectric properties of the cured product can be further reduced.

[0029] By using dimer diamine as the diamine, the dielectric properties of the cured product can be reduced. On the other hand, when dimer diamine is used alone as the amine, the elastic modulus and Tg of the cured product decrease. In contrast, by using a second amine, particularly a diamine other than dimer diamine, in combination with dimer diamine, the elastic modulus and Tg of the cured product can be improved while maintaining the dielectric properties.

[0030] At least one of the above-mentioned components (a1) and (a2) may contain a compound having a fluorene skeleton. When at least one of the components (a1) and (a2) constituting the maleimide resin contains a compound having a fluorene skeleton, a cured product obtained using the maleimide resin has a high elastic modulus, a high Tg, and a low CTE while sufficiently maintaining a low dielectric constant and a low dielectric dissipation factor. From the viewpoint of further increasing the elastic modulus and Tg of the cured product and decreasing the CTE, both of the above-mentioned components (a1) and (a2) may contain a compound having a fluorene skeleton.

[0031] Maleimide resins can be produced by the following method. For example, first, components (a1) and (a2) are subjected to a polyaddition reaction at a temperature of about 60 to 120°C, preferably 70 to 90°C, typically for about 0.1 to 2 hours, preferably 0.1 to 1.0 hours. Next, the resulting polyaddition product is subjected to an imidization reaction, i.e., a dehydration ring-closing reaction, at a temperature of about 80 to 250°C, preferably 100 to 200°C, for about 0.5 to 30 hours, preferably 0.5 to 10 hours (imidization step). The imidization step is carried out in the presence of an organic solvent containing at least one of γ-butyrolactone and N-ethyl-2-pyrrolidone. Subsequently, the product obtained by the dehydration ring-closing reaction and component (a3) ​​are subjected to a maleimidation reaction, i.e., a dehydration ring-closing reaction, at a temperature of about 60 to 250°C, preferably 80 to 200°C, for about 0.5 to 30 hours, preferably 0.5 to 10 hours (maleimidation step). The polyaddition reaction, imidization, and maleimidization reaction may be carried out under atmospheric pressure (normal pressure), reduced pressure, or increased pressure.

[0032] The organic solvent used in this embodiment contains at least one of γ-butyrolactone and N-ethyl-2-pyrrolidone. By using at least one of γ-butyrolactone and N-ethyl-2-pyrrolidone, it is possible to produce a maleimide resin that can improve the storage stability of the resin composition. Here, it is believed that the reason why the storage stability of the resin composition can be improved is because the use of the organic solvent makes it possible to obtain a maleimide resin with a low amine value, thereby suppressing reactions in the resin composition.

[0033] From the viewpoint of improving the storage stability of the resin composition, the content of γ-butyrolactone and N-ethyl-2-pyrrolidone in the organic solvent (the total content when both γ-butyrolactone and N-ethyl-2-pyrrolidone are contained) is preferably 5% by mass or more, more preferably 8 to 40% by mass, and particularly preferably 8 to 25% by mass, based on the total amount of the organic solvent.

[0034] The organic solvent may be a mixed solvent composed of a plurality of organic solvents, and the mixed solvent may contain an organic solvent other than γ-butyrolactone and N-ethyl-2-pyrrolidone. The mixed solvent preferably contains an aromatic hydrocarbon with a boiling point of 150°C or higher, from the viewpoints of easily dissolving the components (a1) and (a2) in the mixed solvent, shortening the reaction time of the dehydration ring-closing reaction in the imidization step and the maleimide step, and enabling the synthesis of a maleimide resin in a short period of time. Furthermore, the mixed solvent preferably contains an alcohol with a boiling point of 100°C or lower, from the viewpoint of half-esterifying the component (a1). Half-esterifying the component (a1) makes the component (a1) more soluble in the mixed solvent, promoting the dehydration ring-closing reaction in the imidization step, and suppressing side reactions. Furthermore, using an alcohol with a temperature of 100°C or lower facilitates elimination of the alcohol component during the dehydration ring-closing reaction in the imidization step, thereby improving the ring-closure rate of imidization and shortening the reaction time. In this specification, the boiling point means the boiling point under atmospheric pressure (1013 hPa).

[0035] Examples of aromatic hydrocarbons having a boiling point of 150°C or higher include solvent naphtha, mesitylene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene (pseudocumene), tetralin, etc. Among these, solvent naphtha, mesitylene, and pseudocumene are preferred from the viewpoint of boiling point. These can be used alone or in combination of two or more.

[0036] The boiling point of the aromatic hydrocarbon is 150° C. or higher, but from the viewpoint of performing the synthesis more efficiently in a shorter time, it may be 155° C. or higher or 160° C. or higher. On the other hand, from the viewpoint of further reducing the amount of solvent remaining in the synthesized maleimide resin, the boiling point of the aromatic hydrocarbon may be 210° C. or lower, 200° C. or lower, or 180° C. or lower.

[0037] Examples of alcohols having a boiling point of 100°C or less include methanol, ethanol, 1-propanol, and isopropanol. These can be used alone or in combination of two or more. Among these, methanol and ethanol are particularly preferred from the viewpoint of ease of elimination during imide ring closure. Here, the ease of hydrolysis of an ester generally depends on the number of carbon atoms (boiling point) of the alcohol, and the lower the boiling point of the alcohol, the higher the elimination ability and the easier it is to be eliminated during imide ring closure. Therefore, methanol and ethanol are preferred as alcohols.

[0038] The mixed solvent may contain other solvents in addition to those described above. Examples of other solvents include methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, ethylene glycol monomethyl ether, N,N'-dimethylformamide, N-methylcaprolactam, methyl triglyme, methyl diglyme, 1-butanol, benzyl alcohol, cresol, propylene glycol monomethyl ether, methyl isobutyl carbinol, 1-propoxy-2-propanol, cyclopentanone, cyclohexanone, and methylcyclohexane. These may be used alone or in combination of two or more. The content of these other solvents may be 10% by mass or less, based on the total amount of the mixed solvent.

[0039] In the imidization reaction or maleimidization reaction, various known reaction catalysts, dehydrating agents, etc. can be used. Examples of reaction catalysts include aliphatic tertiary amines such as triethylamine, aromatic tertiary amines such as dimethylaniline, heterocyclic tertiary amines such as pyridine, picoline, and isoquinoline, and organic acids such as methanesulfonic acid and paratoluenesulfonic acid monohydrate. These can be used alone or in combination of two or more. Examples of dehydrating agents include aliphatic acid anhydrides such as acetic anhydride, and aromatic acid anhydrides such as benzoic anhydride. These can be used alone or in combination of two or more.

[0040] The production method of this embodiment may include a water-washing step in which the maleimide resin obtained after the maleimidation step is washed with water to purify it. The water-washing step can be performed by adding the maleimide resin obtained together with an organic solvent to water, stirring the mixture, separating the stirred solution into an aqueous layer and an oil layer (organic layer), and removing the aqueous layer. This series of operations may be repeated two or more times. The water-washing step may also be performed at a liquid temperature of 50 to 100°C. By performing the water-washing step, ionic impurities can be removed. The oil layer containing the recovered maleimide resin can be heated to remove water. The maleimide resin after water removal can be heated to remove the solvent. This solvent removal may be performed under reduced pressure. The degree of vacuum can be 0.06 to 0.10 MPa below atmospheric pressure, and the mixture can be heated at a temperature of 80 to 150°C for 0.2 to 10.0 hours.

[0041] The maleimide resin obtained by the production method of this embodiment may have multiple maleimide groups in the molecule. The maleimide resin may be a bismaleimide resin. The assumed structure of the maleimide resin produced by the above method is shown in the following general formula (4). General formula (4) assumes the case where the second amine is a diamine.

[0042] In general formula (4), X each independently represents a tetravalent organic group, Y each independently represents a divalent organic group, and a represents an integer of 1 or more. However, at least one of the multiple Y's represents a divalent organic group derived from the above-mentioned dimer diamine, and at least one of the multiple Y's represents a divalent organic group derived from the above-mentioned second amine (diamine). Furthermore, X and Y may be an organic group having an aliphatic group, an alicyclic structure, or an aromatic ring, and they may contain a heteroatom. Furthermore, at least one of X and Y may be an organic group having a fluorene skeleton.

[0043] The molecular weight of the maleimide resin can be controlled by the number of moles of the (a1) component and the (a2) component, and the smaller the number of moles of the (a1) component is relative to the number of moles of the (a2) component, the smaller the molecular weight can be. For the purpose of easily achieving the effects of the present disclosure, the number of moles of the (a1) component per 1.00 mole of the (a2) component, i.e., [number of moles of the (a1) component] / [number of moles of the (a2) component], is usually in the range of about 0.30 to 1.00, preferably 0.30 to 0.95, more preferably 0.30 to 0.90, and even more preferably 0.50 to 0.80.

[0044] From the viewpoint of solubility in solvents and heat resistance, the molecular weight of the maleimide resin is preferably a weight average molecular weight (Mw) of 3,000 to 30,000, more preferably 3,000 to 25,000, even more preferably 5,000 to 23,000, and particularly preferably 7,000 to 20,000. When the weight average molecular weight is 30,000 or less, solubility in organic solvents is good, and when it is 3,000 or more, the effect of improving heat resistance tends to be sufficiently obtained. Mw can be measured by gel permeation chromatography (GPC) and converted using a calibration curve of standard polystyrene.

[0045] From the viewpoint of enhancing the storage stability of a resin composition containing the maleimide resin, the amine value of the maleimide resin is preferably 1.5 mgKOH / g or less, more preferably 1.0 mgKOH / g or less, and particularly preferably 0.6 mgKOH / g or less. The production method of this embodiment makes it possible to produce a maleimide resin with a reduced amine value.

[0046] <Resin Composition> The maleimide resin can be used as a resin composition. The resin composition may be a photosensitive resin composition. In this case, the photosensitive resin composition is applied to a substrate and dried to form a resin film, and the resin film is exposed to light and developed to obtain a patterned resin film (a patterned resin film). The patterned resin film can then be heat-cured to form a patterned cured film (a patterned cured film), which can be used as an insulating film. Hereinafter, a case where the resin composition is a photosensitive resin composition will be described.

[0047] The photosensitive resin composition contains the maleimide resin (hereinafter also referred to as "component (A)"). In the photosensitive resin composition, the maleimide resin may be used alone or in combination of two or more. The photosensitive resin composition may further contain a crosslinking agent and a photopolymerization initiator. Furthermore, the photosensitive resin composition may further contain a thermal polymerization initiator, a coupling agent, a rust inhibitor, a polymerization inhibitor, etc., as necessary. The photosensitive resin composition according to this embodiment is a negative photosensitive resin composition, and a cured product of the photosensitive resin composition can be suitably used as an insulating film for a rewiring layer. Hereinafter, each component used in the photosensitive resin composition according to this embodiment will be described in more detail.

[0048] (Crosslinking Agent) The crosslinking agent (hereinafter also referred to as "component (B)") may be a polymerizable crosslinking agent. The polymerizable group may be a photopolymerizable group or a thermally polymerizable group. Examples of the polymerizable group include a (meth)acryloyl group, an allyl group, and a vinyl group. The component (B) may be a polyfunctional compound having two or more polymerizable groups. Furthermore, the component (B) can crosslink not only with each other but also with the component (A), for example, during exposure of the resin composition. Furthermore, the component (B) can crosslink with each other, for example, during heating of the resin film after pattern formation. The component (B) can be used alone or in combination of two or more.

[0049] From the viewpoint of dielectric properties, the resin composition according to this embodiment may contain a polymerizable crosslinking agent having a (meth)acryloyl group as a crosslinking agent. The polymerizable crosslinking agent having a (meth)acryloyl group can crosslink not only with itself but also with component (A) during exposure of the photosensitive layer. The polymerizable crosslinking agent having a (meth)acryloyl group may be an acrylate compound or a methacrylate compound. From the viewpoint of dielectric properties, component (B) may contain a methacrylate compound.

[0050] Examples of polymerizable crosslinking agents having a (meth)acryloyl group include tricyclodecane dimethanol di(meth)acrylate, tris-(2-(meth)acryloyloxyethyl)isocyanurate, dioxane glycol di(meth)acrylate, alkoxylated glycerin tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, alkoxylated trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, alkoxylated pentaerythritol tetra(meth)acrylate, and 1,6-hexane. Examples of the diol di(meth)acrylate include diol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, propoxylated ethoxylated bisphenol A (meth)acrylate, dipentaerythritol poly(meth)acrylate, alkoxylated dipentaerythritol poly(meth)acrylate, ethoxylated isocyanuric acid tri(meth)acrylate, polyethylene glycol di(meth)acrylate, and polypropylene glycol di(meth)acrylate.

[0051] The polymerizable crosslinking agent having a (meth)acryloyl group may contain at least one selected from the group consisting of tricyclodecane dimethanol di(meth)acrylate, tris-(2-(meth)acryloyloxyethyl)isocyanurate, and dioxane glycol di(meth)acrylate, from the viewpoints of heat resistance, dielectric properties, and microprocessability, and may contain tris-(2-(meth)acryloyloxyethyl)isocyanurate from the viewpoints of heat resistance and dielectric properties.

[0052] The resin composition according to the present embodiment may contain a polymerizable crosslinking agent having an allyl group or a vinyl group as a crosslinking agent from the viewpoints of dielectric properties and heat resistance. The polymerizable crosslinking agent having an allyl group or a vinyl group can crosslink with itself when the resin film is heated after pattern formation.

[0053] Examples of polymerizable crosslinking agents having an allyl group include 1,3,4,6-tetraallyl glycoluril, triallyl isocyanurate, diallyl monoglycidyl isocyanurate, diallyl monomethyl isocyanurate, diallyl isocyanurate, triallyl trimellitate, and triallyl orthoformate.

[0054] Examples of the polymerizable crosslinking agent having a vinyl group include a polyvinylbenzyl compound and a polyvinylbenzyl ether compound.

[0055] From the viewpoints of dielectric properties and microprocessability, the polymerizable crosslinking agent having an allyl group or a vinyl group may include at least one selected from the group consisting of 1,3,4,6-tetraallyl glycoluril, triallyl isocyanurate, diallyl isocyanurate, and a polyvinyl benzyl ether compound, or may include triallyl isocyanurate.

[0056] From the viewpoint of further improving the balance between low dielectric properties and micro-processability, the content of component (B) is preferably less than 50 parts by mass, and may be 1 to 45 parts by mass, 5 to 40 parts by mass, 8 to 30 parts by mass, or 10 to 20 parts by mass, when the total amount of component (A) and component (B) is 100 parts by mass.

[0057] (Photopolymerization initiator) The photopolymerization initiator (hereinafter also referred to as "component (C)") is not particularly limited as long as it is a compound that initiates polymerization upon irradiation with actinic rays (ultraviolet rays, etc.), and examples thereof include alkylphenone-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, intramolecular hydrogen abstraction photopolymerization initiators, and oxime ester-based photopolymerization initiators.

[0058] Alkylphenone-based photopolymerization initiators are commercially available, for example, from IGM Resins B.V. as Omnirad 651, Omnirad 184, Omnirad 1173, Omnirad 2959, Omnirad 127, Omnirad 907, Omnirad 369, Omnirad 379EG, etc. Acylphosphine oxide-based photopolymerization initiators are commercially available, for example, from IGM Resins B.V. as Omnirad 819, Omnirad TPO H, etc. Intramolecular hydrogen abstraction photopolymerization initiators are commercially available, for example, from IGM Resins B.V. Omnirad MBF, Omnirad 754, etc. manufactured by BASF Japan Ltd. Oxime ester photopolymerization initiators are commercially available, for example, as Irgacure OXE01, Irgacure OXE02, etc. manufactured by BASF Japan Ltd. In order to promote the photoreaction, a titanocene photopolymerization initiator (for example, Irgacure 784 manufactured by BASF Japan Ltd.) may be used in combination.

[0059] The content of the component (C) may be 0.1 to 10 parts by mass, 0.5 to 8 parts by mass, or 1 to 5 parts by mass per 100 parts by mass of the total amount of the component (A) and the component (B), because excellent micro-processability is easily obtained.

[0060] (Thermal Polymerization Initiator) The photosensitive resin composition according to this embodiment may further contain a thermal polymerization initiator as component (D) from the viewpoint of promoting the polymerization reaction of the thermally polymerizable crosslinking agent. The component (D) is preferably a compound that decomposes upon heating during curing to generate radicals and promote the polymerization reaction of components (A) and (B). Examples of the component (D) include organic peroxides.

[0061] Examples of organic peroxides include methyl ethyl ketone peroxide, methylcyclohexanone peroxide, methylacetoacetate peroxide, acetylacetone peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-hexylperoxy)cyclohexane, 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, 2,2-bis(4,4-di-t-butylperoxy)cyclohexane, t-butylperoxycyclohexyl)propane, 1,1-bis(t-butylperoxy)cyclododecane, n-butyl-4,4-bis(t-butylperoxy)valerate, 2,2-bis(t-butylperoxy)butane, 1,1-bis(t-butylperoxy)-2-methylcyclohexane, t-butyl hydroperoxide, p-menthane hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, t-hexyl hydroperoxide, dicumyl peroxide, 2,5-dimethyl -2,5-bis(t-butylperoxy)hexane, α,α'-bis(t-butylperoxy)diisopropylbenzene, t-butylcumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3, isobutyryl peroxide, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, cinnamic acid peroxide, m-toluoyl peroxide, benzoyl peroxide, diisopropyl Peroxydicarbonate, bis(4-t-butylcyclohexyl)peroxydicarbonate, di-3-methoxybutyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, di(3-methyl-3-methoxybutyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, α,α'-bis(neodecanoylperoxy)diisopropylbenzene, cumyl peroxyneodecanoate, 1,1,3,3,-Tetramethylbutylperoxyneodecanoate, 1-cyclohexyl-1-methylethylperoxyneodecanoate, t-hexylperoxyneodecanoate, t-butylperoxyneodecanoate, t-hexylperoxypivalate, t-butylperoxypivalate, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxy Examples of peroxybenzoates include tert-butylperoxymethyl ...

[0062] The content of the (D) component is not particularly limited, but may be 0.1 to 10.0 parts by mass, 0.5 to 5.0 parts by mass, or 0.7 to 3.0 parts by mass relative to 100 parts by mass of the total amount of the (A) component and the (B) component.

[0063] (Coupling Agent) The photosensitive resin composition according to this embodiment may further contain a coupling agent from the viewpoint of improving the adhesion of a cured product of the photosensitive resin composition. The coupling agent may be a silane coupling agent. The silane coupling agent may have, for example, a vinyl group, an epoxy group, a styryl group, an acryloyl group, a methacryloyl group, an amino group, a ureido group, an isocyanate group, an isocyanurate group, or a mercapto group.

[0064] Examples of silane coupling agents having a vinyl group include KBM-1003 and KBE-1003 (trade names manufactured by Shin-Etsu Chemical Co., Ltd.; the same applies hereinafter). Examples of silane coupling agents having an epoxy group include KBM-303, 402, 403, KBE-402, 403, X-12-981S, and X-12-984S. Examples of silane coupling agents having a styryl group include KBM-1403. Examples of silane coupling agents having a methacryloyl group include KBM-502, 503, KBE-502, and 503. Examples of silane coupling agents having an acryloyl group include KBM-5103, X-12-1048, and X-12-1050. Examples of silane coupling agents having an amino group include KBM-602, 603, 903, 573, 575, KBE-903, 9103P, and X-12-972F. Examples of silane coupling agents having a ureido group include KBE-585. Examples of silane coupling agents having an isocyanate group include KBE-9007 and X-12-1159L. Examples of silane coupling agents having an isocyanurate group include KBM-9659. Examples of silane coupling agents having a mercapto group include KBM-802, 803, X-12-1154, and X-12-1156. The silane coupling agent may be a silane coupling agent having a methacryloyl group. The silane coupling agents may be used alone or in combination of two or more.

[0065] The content of the silane coupling agent may be 0.01 to 10 parts by mass, 0.1 to 8 parts by mass, or 0.5 to 5 parts by mass relative to 100 parts by mass of the total amount of the components (A) and (B).

[0066] (Rust inhibitor) The photosensitive resin composition according to this embodiment may further contain a rust inhibitor in order to suppress corrosion or prevent discoloration of copper wiring. Examples of the rust inhibitor include triazole derivatives such as benzotriazole, and tetrazole derivatives. The rust inhibitor may be used alone or in combination of two or more.

[0067] The content of the rust inhibitor may be 0.01 to 10 parts by mass, 0.1 to 5 parts by mass, or 0.5 to 3 parts by mass, per 100 parts by mass of the total amount of components (A) and (B).

[0068] (Polymerization Inhibitor) The photosensitive resin composition according to this embodiment may further contain a polymerization inhibitor from the viewpoint of storage stability.

[0069] Examples of polymerization inhibitors include 4-tert-butylcatechol, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy radical, p-methoxyphenol, diphenyl-p-benzoquinone, benzoquinone, hydroquinone, pyrogallol, phenothiazine, resorcinol, ortho-dinitrobenzene, para-dinitrobenzene, meta-dinitrobenzene, phenanthraquinone, N-phenyl-2-naphthylamine, cupferron, 2,5-toluquinone, tannic acid, parabenzylaminophenol, tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanuric acid, and nitrosamines. One type of polymerization inhibitor may be used alone, or two or more types may be used in combination.

[0070] The content of the polymerization inhibitor may be 0.01 to 10 parts by mass, 0.05 to 5 parts by mass, or 0.10 to 2 parts by mass, relative to 100 parts by mass of the total amount of the components (A) and (B).

[0071] (Sensitizer) The photosensitive resin composition of the present disclosure may further contain a sensitizer from the viewpoint of maintaining both the film remaining rate over a wide range of exposure doses and good resolution.

[0072] Examples of sensitizer components include Michler's ketone, benzoin, 2-methylbenzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, 2-t-butylanthraquinone, 1,2-benzo-9,10-anthraquinone, anthraquinone, methylanthraquinone, 4,4'-bis(diethylamino)benzophenone, acetophenone, benzophenone, thioxanthone, 1,5-acenaphthene, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-[4-(methylthio)phenyl]-2-morpholino-1-propanone, diacetylbenzyl, benzil dimethyl ketal, and benzil dimethyl ketal. Examples of the sensitizer component include phenyl diethyl ketal, diphenyl disulfide, anthracene, phenanthrenequinone, riboflavin tetrabutylate, acridine orange, erythrosine, phenanthrenequinone, 2-isopropylthioxanthone, 2,6-bis(p-diethylaminobenzylidene)-4-methyl-4-azacyclohexanone, 6-bis(p-dimethylaminobenzylidene)-cyclopentanone, 2,6-bis(p-diethylaminobenzylidene)-4-phenylcyclohexanone, aminostyryl ketone, 3-ketocoumarin compounds, biscoumarin compounds, N-phenylglycine, N-phenyldiethanolamine, and 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone.

[0073] When a sensitizer component is contained, the blend amount thereof is preferably 0.1 to 2.0 parts by mass, and more preferably 0.2 to 1.5 parts by mass, per 100 parts by mass of the component (A).

[0074] (Solvent) The photosensitive resin composition according to this embodiment contains a solvent for dissolving and dispersing each component, which makes it easy to apply the composition to a substrate and allows a coating film of uniform thickness to be formed. The solvent may be used alone or in combination of two or more.

[0075] Examples of the solvent include ketones such as methyl ethyl ketone, cyclohexanone, and cyclopentanone; aromatic hydrocarbons such as toluene, xylene, tetramethylbenzene, and pseudocumene; glycol ethers such as methyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether; esters such as ethyl acetate, butyl acetate, butyl cellosolve acetate, carbitol acetate, and γ-butyrolactone; and nitrogen-containing compounds such as mesitylene, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropanamide, and 3-butoxy-N,N-dimethylpropanamide.

[0076] The amount of the solvent to be added is not particularly limited, but may be an amount such that the solid content in the photosensitive resin composition is 5 to 60 mass %, 10 to 50 mass %, or 15 to 40 mass %.

[0077] The preparation method, conditions, etc. of the photosensitive resin composition are not particularly limited. For example, a method may be used in which predetermined amounts of each main component are thoroughly and uniformly stirred and mixed using a mixer or the like, and then kneaded using a mixing roll, an extruder, a kneader, a roll, an extruder, etc. The kneading method is not particularly limited.

[0078] The dielectric constant at 10 GHz of the cured product of the photosensitive resin composition according to this embodiment may be 2.80 or less, 2.75 or less, or 2.70 or less. The dielectric loss tangent at 10 GHz of the cured product of the photosensitive resin composition may be 0.0060 or less, 0.0050 or less, 0.0045 or less, or 0.0040 or less. The dielectric constant and dielectric loss tangent can be measured using a cured film of the photosensitive resin composition by the method described in the examples.

[0079] The photosensitive resin composition according to this embodiment is capable of forming a fine pattern. The photosensitive resin composition according to this embodiment is capable of forming an insulating film that exhibits low dielectric properties and excellent insulating reliability. A semiconductor element having an interlayer insulating layer formed from a cured product of the above-described photosensitive resin composition, and an electronic device including the semiconductor element can be produced. The semiconductor element can have improved high-frequency characteristics by having a rewiring layer including a cured product of the photosensitive resin composition according to this embodiment. The semiconductor element may be, for example, a memory, a package, or the like having a multilayer wiring structure, a rewiring structure, or the like. Examples of electronic devices include mobile phones, smartphones, tablet terminals, personal computers, and hard disk suspensions. By providing a patterned cured film formed from the photosensitive resin composition according to this embodiment, semiconductor elements and electronic devices with excellent reliability can be provided.

[0080] The present disclosure will be specifically described below using examples, but the present disclosure is not limited to these examples.

[0081] <Synthesis of Maleimide Resin> (Example 1) 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (manufactured by JFE Chemical Corporation, trade name "BPAF"), pseudocumene (manufactured by Toyo Gosei Co., Ltd.), Solmix A-11 (trade name, manufactured by Japan Alcohol Sales Co., Ltd., an alcohol-based solvent mainly composed of ethanol), and γ-butyrolactone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were charged into a 1 L flask equipped with a condenser, a nitrogen inlet tube, a thermocouple, a stirrer, and a vacuum pump. After charging, the temperature was raised to 80°C and maintained at that temperature for 0.5 hours, and dimer diamine (DDA) (trade name "PRIAMINE 1075", manufactured by Croda Japan Co., Ltd.) was added dropwise. After the dropwise addition, norbornane diamine (NBDA) (manufactured by Mitsui Chemicals Fine Co., Ltd.) was added dropwise. The temperature was then maintained at 80°C for approximately 0.25 hours. After the incubation, an aqueous methanesulfonic acid solution (manufactured by BASF under the trade name "Lutropur MSA") was added. The temperature was then raised to 160°C. After the temperature was raised, the pressure was reduced from atmospheric pressure to 0.03 MPa, and a dehydration ring-closing reaction was carried out at 160°C under reduced pressure for 2 hours. The water and alcohol in the reaction solution were removed, and an intermediate polyimide resin was obtained (imidization step). The pressure inside the reaction vessel was then returned to atmospheric pressure, and the resulting polyimide resin was cooled to 130°C. Maleic anhydride (manufactured by Fuso Chemical Co., Ltd.) was added, and the temperature was raised to 160°C. The dehydration ring-closing reaction was carried out at 160°C under a reduced pressure of 0.03 MPa from atmospheric pressure for 4 hours. The water in the reaction solution was removed, and a maleimide resin was obtained (maleimide step). The blending amounts (unit: parts by mass) of each component are shown in Table 1. In Table 1, the blending amounts of nonvolatile components other than the organic solvent are shown.

[0082] The resulting maleimide resin was placed in a separatory funnel, and 500 parts by mass of pure water was added. The separatory funnel was shaken and allowed to stand. After standing, the aqueous and organic layers separated, and only the organic layer was recovered. The recovered organic layer was placed in a 0.3 L glass vessel equipped with a cooler, a nitrogen inlet tube, a thermocouple, a stirrer, and a vacuum pump, heated to 88-93°C, and the water was removed. The temperature was then raised to 100°C, and the solvent was partially removed for 0.5 hours under a reduced pressure of 0.1 MPa from atmospheric pressure, yielding a solution of maleimide resin (A-1) (non-volatile content 40% by mass). IR measurement of the resulting maleimide resin (A-1) confirmed the formation of the maleimide resin. The IR spectrum of maleimide resin (A-1) is shown in Figure 1. The IR spectrum was measured by setting the resin solid obtained by drying the maleimide resin solution at 130°C for 30 minutes in an FT-IR measurement device (manufactured by Bruker, trade name "Alpha II Platinum-ATR") and measuring.

[0083] Example 2 A solution of maleimide resin (A-2), component (A) (non-volatile content: 40% by mass), was obtained in the same manner as in Example 1, except that N-ethyl-2-pyrrolidone (NEP) was used instead of γ-butyrolactone and the amounts of each component were changed to those shown in Table 1. IR measurement of the obtained maleimide resin (A-2) was performed in the same manner as in Example 1, and it was confirmed that a maleimide resin was formed. The IR spectrum of maleimide resin (A-2) is shown in FIG. 2.

[0084] Example 3 A solution of maleimide resin (A-3), which is component (A) (non-volatile content: 40% by mass), was obtained in the same manner as in Example 1, except that norbornanediamine (NBDA) and tris(2-aminoethyl)amine (TAEA) were used as the amines, and the amounts of each component were changed to those shown in Table 1. IR measurement of the obtained maleimide resin (A-3) was performed in the same manner as in Example 1, and it was confirmed that a maleimide resin was formed.

[0085] Comparative Example 1 A solution of maleimide resin (A-4), which is component (A) (non-volatile content: 40% by mass), was obtained in the same manner as in Example 1, except that γ-butyrolactone was not used as the organic solvent and the amounts of each component were changed to those shown in Table 1. IR measurement of the obtained maleimide resin (A-4) was performed in the same manner as in Example 1, and it was confirmed that a maleimide resin was formed.

[0086] Comparative Example 2 A solution of maleimide resin (A-5), which is component (A) (non-volatile content: 40% by mass), was obtained in the same manner as in Example 3, except that γ-butyrolactone was not used as the organic solvent and the amounts of each component were changed to those shown in Table 1. The obtained maleimide resin (A-5) was subjected to IR measurement in the same manner as in Example 1, and it was confirmed that a maleimide resin was formed.

[0087] <Measurement of Amine Value> The maleimide resins obtained in the Examples and Comparative Examples were dissolved in a solvent (a mixed solvent of toluene and isopropyl alcohol (IPA) (volume ratio 2:1)) to a concentration of 11% by mass to prepare a sample for amine value measurement. The obtained sample was placed in an automatic potentiometric titrator (manufactured by Kyoto Electronics Manufacturing Co., Ltd., product name "AT-710") and subjected to potentiometric titration with 0.05 mol / L hydrochloric acid. The titer was determined from the titration curve, and the amine value was calculated using the following formula. The results are shown in Table 1. Amine value (mg KOH / g) = 0.05 × f × V × 56.11 × 1000 / W f: hydrochloric acid factor V: titer (L) W: solid content of maleimide resin (2.5 g)

[0088] <Measurement of Weight-Average Molecular Weight (Mw)> The weight-average molecular weight (Mw) of the maleimide resins obtained in the Examples and Comparative Examples was measured by GPC (gel permeation chromatography). A sample prepared by dissolving maleimide resin in tetrahydrofuran (THF) to a concentration of 3% by mass was injected in an amount of 50 μL into a column (one GL-R420 column, one GL-R430 column, one GL-R440 column (all manufactured by Hitachi High-Tech Fielding Corporation)) heated to 30°C. Measurement was performed using THF as the developing solvent at a flow rate of 1.6 mL / min. An L-3350 RI detector (manufactured by Hitachi, Ltd.) was used as the detector, and Mw was calculated from the elution time using a molecular weight / elution time curve created using standard polystyrene (manufactured by Tosoh Corporation). The results are shown in Table 1 as the initial Mw.

[0089] <Preparation of Resin Composition> 85 parts by mass of the maleimide resin solution (40% by mass non-volatile content) obtained in the Examples and Comparative Examples was mixed with 5 parts by mass of A-9300 (crosslinking agent), 10 parts by mass of TAIC (crosslinking agent), 3 parts by mass of OXE01 (photoinitiator), 2 parts by mass of OXE02 (photoinitiator), 1.7 parts by mass of Perbutyl P (thermal initiator), 1.7 parts by mass of KBM-503 (silane coupling agent), 1.7 parts by mass of BT-120G (rust inhibitor), and 0.25 parts by mass of TEMPOL (polymerization inhibitor), and cyclopentanone was added so that the non-volatile content was 40% by mass, thereby obtaining a resin composition. Details of each component are as follows. A-9300: Tris-(2-acryloyloxyethyl)isocyanurate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name "A-9300", number of acryloyl groups: 3) TAIC: Triallyl isocyanurate (manufactured by Mitsubishi Chemical Corporation, trade name "TAIC", number of allyl groups: 3) OXE01: Oxime ester photopolymerization initiator (manufactured by BASF Japan Ltd., trade name "Irgacure OXE01") OXE02: Oxime ester photopolymerization initiator (manufactured by BASF Japan Ltd., trade name "Irgacure OXE02") Perbutyl P: α,α'-bis(t-butylperoxy)diisopropylbenzene (manufactured by NOF Corporation, trade name "Perbutyl P") KBM-503: 3-methacryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-503") BT-120G: 1,2,3-benzotriazole (manufactured by Johoku Chemical Industry Co., Ltd., trade name "BT-120G") TEMPOL: 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy radical (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0090] <Measurement of Viscosity> 1 mL of the resin composition prepared above was placed in a sample holder of an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., product name "RE-85") adjusted to 25°C ± 0.2°C, and the viscosity was measured. The results are shown in Table 1 as initial viscosity.

[0091] <Evaluation of Storage Stability> The resin compositions prepared above were stored in a dark place at 25°C. The Mw of the maleimide resin and the viscosity of the resin compositions after 360 hours and 720 hours of storage were measured using the same methods as above. The storage stability was evaluated based on the obtained results and the following criteria. The results are shown in Table 1. (Criteria) A: The change in measured value after 720 hours of storage compared to the initial value was less than 1000 in Mw and less than 25 mPa·s in viscosity. B: Not corresponding to the criteria A, and the change in measured value after 720 hours of storage compared to the initial value was less than 1500 in Mw or less than 40 mPa·s in viscosity. C: The change in measured value after 720 hours of storage compared to the initial value was more than 1500 in Mw and more than 40 mPa·s in viscosity.

[0092]

Claims

1. A method for producing a maleimide resin obtained by reacting a tetracarboxylic dianhydride (a1), an amine (a2), and maleic anhydride (a3), comprising the steps of: adding the amine (a2) to the tetracarboxylic dianhydride (a1) in the presence of an organic solvent to obtain a polyimide resin; and adding the maleic anhydride (a3) ​​to the polyimide resin to obtain a maleimide resin, wherein the organic solvent contains at least one of γ-butyrolactone and N-ethyl-2-pyrrolidone, and the amine (a2) contains a dimer diamine and a second amine other than the dimer diamine.

2. The method for producing a maleimide resin according to claim 1, wherein at least one of the tetracarboxylic dianhydride (a1) and the amine (a2) contains a compound having a fluorene skeleton.

3. The method for producing a maleimide resin according to claim 1, wherein the tetracarboxylic dianhydride (a1) includes at least one of 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)naphtho[1,2-c]furan-1,3-dione, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride, and 3,3',4,4'-biphenyltetracarboxylic dianhydride.

4. The method for producing a maleimide resin according to claim 1, wherein the second amine contains at least one of norbornanediamine, 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene, and 9,9-bis(4-aminophenyl)fluorene.

5. A method for producing a maleimide resin according to claim 1, wherein the dimer diamine contains at least one of a compound represented by the following general formula (1) and a compound represented by the following general formula (2): [In formulas (1) and (2), m, n, p, and q each represent an integer of 1 or more selected such that m+n=6 to 17 and p+q=8 to 19, and the bond shown by the dashed line represents a carbon-carbon single bond or a carbon-carbon double bond. However, when the bond shown by the dashed line is a carbon-carbon double bond, formulas (1) and (2) have a structure in which the number of hydrogen atoms bonded to each carbon atom constituting the carbon-carbon double bond is reduced by one from the number shown in formulas (1) and (2)] 6. The method for producing a maleimide resin according to claim 1, which comprises reacting 1.00 mole of the amine (a2) with 0.30 to 1.00 mole of the tetracarboxylic dianhydride (a1).

7. The method for producing a maleimide resin according to claim 1, wherein the organic solvent further contains an aromatic hydrocarbon having a boiling point of 150° C. or higher.

8. The method for producing a maleimide resin according to claim 1, wherein the organic solvent further contains an alcohol having a boiling point of 100° C. or less.

9. The method for producing a maleimide resin according to claim 1, wherein the content of said γ-butyrolactone and N-ethyl-2-pyrrolidone in said organic solvent is 5 to 40 mass % based on the total amount of the organic solvent.