Method for producing maleimide resin

Abstract

To provide a method for producing a maleimide resin, which can reduce a residual amount of solvent, enables synthesis in a short time, and can suppress side reactions during synthesis.SOLUTION: There is provided, a method for producing a maleimide resin obtained by reacting a tetracarboxylic acid dianhydride (a1), a diamine (a2), and maleic anhydride (a3), comprising: a half-esterification step of mixing a (a1) component and a mixed solvent to half-esterify the (a1) component; an imidization step of adding a (a2) component to the half-esterified (a1) component to perform a dehydration cyclization reaction to obtain a polyimide resin; and a maleimidization step of adding a (a3) component to the polyimide resin to perform a dehydration cyclization reaction to obtain a maleimide resin, where the mixed solvent comprises an aromatic hydrocarbon having a boiling point of 150°C or higher and an alcohol having a boiling point of 100°C or lower and the (a2) component comprises a dimer diamine and a second diamine other than the dimer diamine.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] With the increasing environmental awareness in recent years, interlayer insulating materials used in printed wiring boards, electronic components and the like are required to meet the demands for mounting electronic components with lead-free solder and achieving flame retardancy through halogen-free formulations. Since lead-free solder is used at a higher temperature than conventional solder, higher heat resistance is required for interlayer insulating materials. In addition, from the viewpoints of product safety and reliability, resins that contain less or generate no volatile components are desired as resins used in interlayer insulating materials.

[0003] Polyimide resins and maleimide resins are suitably used for printed wiring boards and the like as resins with excellent heat resistance (see Patent Documents 1 to 3). Therefore, polyimide resins and maleimide resins have been studied as resins for use in interlayer insulating materials.

[0004] Generally, the synthesis of polyimide resins and maleimide resins involves a dehydration ring-closing reaction, which requires heating to, for example, 160°C or higher. Therefore, organic solvents with a boiling point of 160°C or higher, such as the high-boiling solvents N-methylpyrrolidone (NMP), γ-butyrolactone, or dimethylacetamide, are used. On the other hand, there are also reported examples of synthesizing maleimide resins using toluene, which has a boiling point of about 110°C, as a solvent (see Patent Document 3).

Prior Art Literature

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

[0006] When maleimide resins are synthesized using high-boiling point solvents such as dimethylacetamide, the low volatility of these solvents means that the high-boiling point solvent tends to remain in the resulting maleimide resin. This can lead to longer drying times when forming the maleimide resin into a film, and the residual high-boiling point solvent may cause problems such as swelling and cracking. On the other hand, synthesis methods using toluene require long reaction times, such as more than 10 hours, and necessitate large amounts of reaction catalysts and dehydrating agents.

[0007] Furthermore, methods for synthesizing maleimide resins using solvents with low boiling points, such as toluene, have the problem of easily generating unclosed rings and side reactions during synthesis. When side reactions occur, precipitates other than maleimide resin are formed in the maleimide resin. In addition, when side reactions occur, it is difficult to obtain maleimide resin with a sufficiently high molecular weight in a short time.

[0008] Therefore, the present disclosure aims to provide a method for producing maleimide resin that can reduce the amount of residual solvent, enable synthesis in a short time, and suppress side reactions during synthesis. [Means for solving the problem]

[0009] The inventors of the present invention conducted intensive studies to solve the above problems and found that the above problems can be solved by using a mixed solvent containing two specific solvents, using two specific diamines, and performing the synthesis through a specific process. As a result, the present invention was completed.

[0010] In other words, this disclosure provides the following inventions. [1] A method for producing a maleimide resin by reacting a tetracarboxylic dianhydride (a1), a diamine (a2), and maleic anhydride (a3), comprising: a half-esterification step of mixing the tetracarboxylic dianhydride (a1) with a mixed solvent to half-esterify the tetracarboxylic dianhydride (a1); an imidation step of adding the diamine (a2) to the half-esterified tetracarboxylic dianhydride (a1) to perform a dehydration and cyclization reaction to obtain a polyimide resin; and a maleimidation step of adding the maleic anhydride (a3) ​​to the polyimide resin to perform a dehydration and cyclization reaction to obtain a maleimide resin, wherein the mixed solvent contains an aromatic hydrocarbon with a boiling point of 150°C or higher and an alcohol with a boiling point of 100°C or lower, and the diamine (a2) contains a dimer amine and a second diamine other than a dimer amine. [2] The method for producing a maleimide resin according to [1], wherein the tetracarboxylic dianhydride (a1) contains at least one of the compounds represented by the following formulas (1) to (3). [ka] [ka] [ka] [3] A method for producing maleimide resin according to [1] or [2], wherein the mass ratio of the content of the aromatic hydrocarbon to the content of the alcohol in the mixed solvent (content of the aromatic hydrocarbon / content of the alcohol) is 2 to 6. [4] A method for producing maleimide resin according to any one of [1] to [3] above, wherein the content of the dimeramine in the diamine (a2) is 50 mol% or more based on the total amount of the diamine (a2). [5] The method for producing a maleimide resin according to any one of the above [1] to [4], wherein the second diamine includes at least one selected from the group consisting of 1,3-diaminopropane, norbornanediamine, 4,4'-methylenedianiline, and 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene. [6] The method for producing a maleimide resin according to any one of the above [1] to [5], wherein the dimer diamine includes at least one of a compound represented by the following general formula (4) and a compound represented by the following general formula (5).

Chemical Formula

Chemical Formula

Effect of the Invention

[0011] According to the present disclosure, it is possible to provide a method for producing a maleimide resin that can reduce the residual amount of solvent, can be synthesized in a short time, and can suppress side reactions during synthesis.

[0012] The maleimide resin obtained by the production method of the present disclosure can be used as a resin constituting an insulating material, can reduce both the dielectric constant and dielectric loss tangent of the insulating material (hereinafter, both may be collectively referred to as "dielectric properties"), and in particular can form an insulating material excellent in low dielectric properties in a high frequency band. The maleimide resin obtained by the production method of the present disclosure can be used as a resin composition mixed with a polymerization initiator, an organic solvent and the like. A cured product obtained by curing the resin composition can be used as an adhesive layer. The resin composition is useful not only as an adhesive used in the production of printed circuit boards (build-up substrates, flexible printed wiring boards, etc.) and copper-clad boards for printed wiring boards, but also as semiconductor interlayer materials, coating agents, resist inks, conductive pastes, electrical insulating materials, and the like. MODE FOR CARRYING OUT THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described in detail.

[0014] In the present specification, a numerical range indicated using "~" indicates a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in the present specification, the upper limit or lower limit of the numerical range of one step can be arbitrarily combined with the upper limit or lower limit of the numerical range of another step. In the numerical ranges described in the present specification, the upper limit or lower limit of the numerical range may be replaced with the values shown in the examples. The expression "A or B" only needs to include either A or B, and may include both. Unless otherwise specified, the materials exemplified in the present specification can be used alone or in combination of two or more.

[0015] <Method for producing maleimide resin> The method for producing maleimide resin according to this embodiment is a method for producing maleimide resin obtained by reacting tetracarboxylic dianhydride (a1) (hereinafter also referred to as "component (a1)"), diamine (a2) (hereinafter also referred to as "component (a2)"), and maleic anhydride (a3) ​​(hereinafter also referred to as "component (a3)"), comprising: a half-esterification step of mixing the tetracarboxylic dianhydride (a1) with a mixed solvent to half-esterify the tetracarboxylic dianhydride (a1); an imidation step of adding the diamine (a2) to the half-esterified tetracarboxylic dianhydride (a1) to perform a dehydration and cyclization reaction to obtain a polyimide resin; and a maleimide step of adding the maleic anhydride (a3) ​​to the polyimide resin to perform a dehydration and cyclization reaction to obtain a maleimide resin. Here, the mixed solvent contains an aromatic hydrocarbon with a boiling point of 150°C or higher and an alcohol with a boiling point of 100°C or lower. Furthermore, the above-mentioned diamine (a2) contains a dimer amine and a second diamine other than dimer amine. In this specification, boiling point refers to the boiling point at atmospheric pressure (1013 hPa).

[0016] ((a1) component: tetracarboxylic dianhydride) The component (a1) used in this embodiment is, for example, a compound represented by the following general formula (I). [ka] In formula (I), R 1 R indicates a tetravalent organic group. 1 This may be a substituted or unsubstituted aliphatic hydrocarbon group, a substituted or unsubstituted heteroaliphatic hydrocarbon group, a substituted or unsubstituted aromatic hydrocarbon group, or a tetravalent organic group having a substituted or unsubstituted heteroaromatic hydrocarbon group. The aliphatic hydrocarbon group may be an alicyclic hydrocarbon group. The tetravalent organic group may be an organic group having 4 to 30 carbon atoms. 1Examples of compounds include aromatic hydrocarbons (aryls) such as benzene, naphthalene, perylene, and biphenyl; compounds having aromatic hydrocarbon groups such as diphenyl ether, diphenyl sulfone, diphenylpropane, diphenylhexafluoropropane, and benzophenone; heteroaromatic hydrocarbons such as pyrrole, furan, thiophene, oxazole, thiazole, pyridine, primidine, quinoline, coumarin, indole, benzofuran, acridine, phenoxazine, and carbazole; compounds having heteroaromatic hydrocarbon groups such as dipyridyl disulfide; aliphatic hydrocarbons (alkanes) such as butane, cyclobutane, and cyclopentane; and heteroaliphatic hydrocarbons such as piperidine, piperazine, morpholine, and pyrrolidine. It is preferable that the aromatic hydrocarbon group is obtained by removing four hydrogen atoms from an aromatic hydrocarbon. 1 From the viewpoint of improving the heat resistance and availability of the resulting maleimide resin, it is preferable that the group is obtained by removing four hydrogen atoms from an aromatic hydrocarbon, and more preferably that it is obtained by removing four hydrogen atoms from benzene or biphenyl.

[0017] From the viewpoint of further improving the solubility of component (a1) in the mixed solvent, it is preferable that component (a1) contains a fluorine-containing tetracarboxylic dianhydride or a tetracarboxylic dianhydride having an alicyclic structure. It is preferable that component (a1) contains at least one of the compounds represented by the following formulas (1) to (3) as a fluorine-containing tetracarboxylic dianhydride or a tetracarboxylic dianhydride having an alicyclic structure. [ka] [ka] [ka]

[0018] The compound represented by formula (1) above is 4,4'-(hexafluoroisopropylidene)diphthalic anhydride. The compound represented by formula (2) above is 1,3,3a,4,5,9b-hexahydro-5(tetrahydro-2,5-dioxo-3-furanyl)naphtho[1,2-C]furan-1,3-dione. The compound represented by formula (3) above is 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride. By using these compounds as component (a1), the solubility of component (a1) in the mixed solvent is increased, enabling the synthesis of maleimide resin in a short time. Furthermore, by using these compounds as component (a1), it is possible to improve the elastic modulus and Tg of the cured product (hereinafter sometimes simply referred to as "cured product") while sufficiently maintaining the low dielectric constant and low dielectric loss tangent of the composition containing the resulting maleimide resin.

[0019] Examples of tetracarboxylic dianhydrides having an alicyclic structure other than those mentioned above include norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic dianhydride, binorbornanetetracarboxylic 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]octane-2,3,5,6-tetracarboxylic 2,3:5,6-dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, bicyclo[2.2.2]octo-7-ene-2,3,5,6-tetracarboxylic dianhydride, and dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride.

[0020] Component (a1) may include fluorine-containing tetracarboxylic dianhydrides and other tetracarboxylic dianhydrides other than those having an alicyclic structure. Other tetracarboxylic dianhydrides that are known as raw materials for polyimides can be used. Specifically, pyromellitic anhydride and compounds represented by the following general formula (6) are examples. [ka] [In formula (6), X represents a single bond or at least one group selected from the following group.] [ka]

[0021] Other tetracarboxylic dianhydrides include, for example, pyromellitic anhydride, 4,4'-oxydiphthalic acid dianhydride, 3,3',4,4'-diphenylsulfone tetracarboxylic acid dianhydride, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride, 4,4'-(4,4'-isopropylidene diphenoxy)diphthalic acid anhydride, bis(1, Examples include 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, 3,4'-oxydiphthalic anhydride, 3,4'-biphthalic anhydride, and 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorenodioanhydride. These can be used individually or in combination of two or more.

[0022] (a1) The total content of the compounds represented by the above formulas (1) to (3) in component (a1) may be 50 mol% or more, 70 mol% or more, or 100 mol% based on the total amount of component (a1), from the viewpoint of further improving the elastic modulus and Tg of the cured product.

[0023] ((a2) Component: Diamine) (a2) Component contains a dimer amine (first diamine) and a second diamine other than a dimer amine.

[0024] Dimer amines are compounds derived from dimer acids, which are dimers of unsaturated fatty acids such as oleic acid, as described, for example, in Japanese Patent Publication No. 9-12712. In this embodiment, known dimer amines can be used without particular limitation, but those represented by the following general formulas (4) and / or (5) are preferred.

[0025] [ka] [ka] [In equations (4) and (5), m, n, p, and q represent integers of 1 or more selected such that m+n = 6 to 17 and p+q = 8 to 19, respectively. The dashed lines indicate carbon-carbon single bonds or carbon-carbon double bonds. However, if the dashed line indicates a carbon-carbon double bond, equations (4) and (5) will 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 equations (4) and (5).]

[0026] As for the dimer amine, those represented by the above general formula (5) are preferred from the viewpoint of solubility in mixed solvents, heat resistance, heat adhesion, and low viscosity, and compounds represented by the following formula (7) are particularly preferred. [ka]

[0027] Examples of commercially available dimer amines include PRIAMINE 1075 and PRIAMINE 1074 (both manufactured by Croda Japan Co., Ltd.). These can be used individually or in combination of two or more.

[0028] The second type of diamine is a diamine that does not fall under the category of dimer amines mentioned above.Examples of the second diamine include 1,3-diaminopropane, norbornanediamine, 4,4'-methylenedianiline, 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene, 1,4-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, and 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[5.2.1.02,6]decane, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, isophoronediamine, 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(2-methylcyclohexylamine), 1,1-bis(4-amino Phenyl)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) Examples include (nophenoxy)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, 2-methyl-1,5-diaminopentane, etc.These can be used individually or in combination of two or more types.

[0029] Dimer amine exhibits excellent solubility in nonpolar solvents. Therefore, the inclusion of dimer amine in component (a2) enhances its solubility in mixed solvents containing aromatic hydrocarbons, enabling the rapid synthesis of maleimide resin. Furthermore, using dimer amine as the diamine can lower the dielectric properties of the cured product. Additionally, using a second diamine in combination with dimer amine as component (a2) improves the elastic modulus and Tg of the cured product compared to using dimer amine alone.

[0030] In component (a2), the content of dimeramine may be 50 mol% or more, 50 to 80 mol%, or 55 to 75 mol%, based on the total amount of component (a2). When the dimeramine content is 50 mol% or more, the solubility of component (a2) in a mixed solvent containing aromatic hydrocarbons is further increased, enabling the synthesis of maleimide resin in a shorter time and lowering the dielectric properties of the cured product. On the other hand, when the dimeramine content is 80 mol% or less, the elastic modulus and Tg of the cured product can be further improved.

[0031] (Amount of tetracarboxylic dianhydride (a1) and diamine (a2)) In the method for producing maleimide resin according to this embodiment, the molecular weight of the final maleimide resin can be controlled by the blending ratio of tetracarboxylic dianhydride (a1) and diamine (a2). The ratio may be 0.30 to 0.95 moles, 0.40 to 0.90 moles, or 0.55 to 0.80 moles of tetracarboxylic dianhydride (a1) per 1.0 mole of diamine (a2). By setting the ratio of tetracarboxylic dianhydride (a1) to 0.95 moles or less, more maleimide groups can be introduced through reaction, making it easier to improve the elastic modulus and Tg after curing. Furthermore, by setting the ratio of tetracarboxylic dianhydride (a1) to 0.30 moles or more, the amount of low molecular weight components can be reduced, and it tends to be easier to obtain a maleimide resin with good heat resistance.

[0032] (Amount of maleic anhydride (a3) ​​included) Maleic anhydride (a3) ​​is added to the maleimide resin in the maleimide process after the polyimide resin intermediate has been synthesized in the imidation process. The amount of maleic anhydride (a3) ​​added may be 2.0 to 4.0 moles or 2.2 to 3.0 moles per mole of polyimide resin. When the amount is 2.0 moles or more, side reactions can be suppressed and the heat resistance of the resulting maleimide resin tends to be improved, while when the amount is 4.0 moles or less, the maleimide resin tends to be easier to purify.

[0033] (Mixed solvent) The mixed solvent used in this embodiment contains an aromatic hydrocarbon with a boiling point of 150°C or higher and an alcohol with a boiling point of 100°C or lower.

[0034] The presence of aromatic hydrocarbons with a boiling point of 150°C or higher in the mixed solvent facilitates the dissolution of components (a1) and (a2) in the mixed solvent, and shortens the reaction time for the dehydration and ring-closing reactions in the imidation and maleimidation steps, thereby enabling the synthesis of maleimide resin in a short time.

[0035] Furthermore, by including an alcohol with a boiling point of 100°C or lower in the mixed solvent, component (a1) can be half-esterified in the half-esterification step. Half-esterifying component (a1) makes it easier to dissolve in the mixed solvent, which promotes the dehydration and ring-closing reaction in the imidation step and suppresses side reactions. In addition, by using an alcohol with a boiling point of 100°C or lower, the alcohol component is easily removed during the dehydration and ring-closing reaction in the imidation step, which improves the ring-closing rate of imidation and shortens the reaction time.

[0036] Examples of aromatic hydrocarbons with a boiling point of 150°C or higher include solvent naphtha, mesitylene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, and tetralin. Among these, solvent naphtha and mesitylene are preferred from the viewpoint of boiling point. These can be used individually or in combination of two or more.

[0037] The boiling point of the above aromatic hydrocarbon is 150°C or higher, but from the viewpoint of synthesizing it more efficiently in a shorter time, it may be 155°C or higher, or even 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 above aromatic hydrocarbon may be 210°C or lower, or even 180°C or lower.

[0038] Alcohols with a boiling point of 100°C or lower include methanol, ethanol, 1-propanol, and isopropanol. These can be used individually 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 alcohols with lower boiling points have higher elimination ability and are easier to eliminate during imide ring closure. For this reason, methanol and ethanol are preferred among the alcohols.

[0039] In the manufacturing method of this embodiment, by using a mixed solvent of the above aromatic hydrocarbon and the above alcohol, the (a1) component, which has been half-esterified with the alcohol, can be easily dissolved by the aromatic hydrocarbon. Therefore, compared to the case in which aromatic hydrocarbons are used alone without the use of alcohol, by using the above mixed solvent, the reaction can be carried out more uniformly, the degree of dispersion of the molecular weight of the resulting maleimide resin can be reduced, side reactions can be suppressed, and residual raw materials can be suppressed.

[0040] In the mixed solvent, the mass ratio of the aromatic hydrocarbon content to the alcohol content (aromatic hydrocarbon content / alcohol content) may be 2 to 6 or 3 to 5. When this mass ratio is 6 or less, maleimide resin tends to be synthesized more easily in a shorter time, and when it is 2 or more, component (a1) is more easily half-esterified in the half-esterification step, and the half-esterified component (a1) is more easily dissolved, allowing the reaction to be carried out more uniformly.

[0041] The mixed solvent may or may not further contain other solvents other than aromatic hydrocarbons with a boiling point of 150°C or higher and alcohols with a boiling point of 100°C or lower. Examples of other solvents include methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, ethylene glycol monomethyl ether, N,N'-dimethylformamide, N-methyl caprolactam, methyl triglyceride, methyl diglyme, 1-butanol, benzyl alcohol, cresol, propylene glycol monomethyl ether, methyl isobutylcarbinol, 1-propoxy-2-propanol, cyclopentanone, cyclohexanone, methylcyclohexane, etc. These can be used individually 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.

[0042] (Additional ingredients) In the imidation or maleimidation process, various known reaction catalysts and dehydrating agents 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, or organic acids such as methanesulfonic acid and p-toluenesulfonic acid monohydrate. These can be used individually 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 individually or in combination of two or more.

[0043] (Half-esterification process) In the half-esterification step, the tetracarboxylic dianhydride (a1) is mixed with a mixed solvent to perform half-esterification of the tetracarboxylic dianhydride (a1). Half-esterification can be carried out at a temperature of about 60 to 120°C, preferably 70 to 90°C, for a period of about 0.1 to 2 hours, preferably 0.1 to 1.0 hour.

[0044] (Imidification process) In the imidation step, a diamine (a2) is added to the half-esterified tetracarboxylic dianhydride (a1) to carry out a dehydration and ring-closing reaction to obtain a polyimide resin. The dehydration and ring-closing reaction in the imidation step can be carried out 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. In the imidation step, the above-mentioned additive components may be added to the reaction solution. In addition, a solvent may be further added in the imidation step. As the solvent, the above-mentioned mixed solvent may be added, or other solvents other than aromatic hydrocarbons with a boiling point of 150°C or higher and alcohols with a boiling point of 100°C or lower may be added. Other solvents include those mentioned above.

[0045] During the imidation process, it is preferable to remove the alcohol from the reaction solution along with water. After the imidation process, an intermediate, a polyimide resin, is obtained.

[0046] (Maleimidization process) In the maleimidation step, maleic anhydride (a3) ​​is added to the polyimide resin obtained in the imidation step to carry out a dehydration and ring-closing reaction to obtain a maleimide resin. The dehydration and ring-closing reaction in the maleimidation step can be carried out 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. In the maleimidation step, the above-mentioned additive components may be added to the reaction solution.

[0047] The manufacturing method of this embodiment may include a water washing step after the maleimide conversion step, in which the obtained maleimide resin is purified by washing it with water. The water washing can be performed by adding the obtained maleimide resin to water together with an organic solvent and stirring, separating the mixed 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 may also be performed at a liquid temperature of 50 to 100°C. Ionic impurities can be removed by performing the water washing step. The oil layer containing the recovered maleimide resin can be heated to remove the water. The maleimide resin after the water has been removed can be heated to remove the solvent. This solvent removal may be performed under reduced pressure. The degree of reduced pressure can be 0.06 to 0.10 MPa from atmospheric pressure, and the mixture can be heated at a temperature of 80 to 150°C for 0.2 to 10.0 hours.

[0048] Through the above process, a maleimide resin can be obtained. The maleimide resin may have multiple maleimide groups in its molecule. The maleimide resin may be a bismaleimide resin. As for the molecular weight of the maleimide resin, from the viewpoint of solubility in solvents and heat resistance when used as a resin composition, a weight-average molecular weight of 3,000 to 25,000 is preferred, and 7,000 to 20,000 is more preferred. When the weight-average molecular weight is 25,000 or less, solubility in organic solvents is good, and when it is 3,000 or more, a sufficient effect of improving heat resistance tends to be obtained.

[0049] <Resin composition> Maleimide resins can be used as resin compositions. Maleimide resins can be used individually or in combination of two or more types. The resin composition may further contain polymerization initiators. The resin composition may also further contain organic solvents.

[0050] (Polymerization initiator) Examples of polymerization initiators include organic peroxides, imidazole compounds, phosphine compounds, and phosphonium salt compounds. These can be used individually or in combination of two or more. Among these, imidazole compounds are particularly preferred because they have excellent function as polymerization initiators and also exhibit excellent low dielectric properties.

[0051] Examples of organic peroxides include methyl ethyl ketone peroxide, methylcyclohexanone peroxide, methyl acetate 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, and 2,2-bis(4,4-di-t-butylperoxy). (Tyl peroxycyclohexyl)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)hexine-3, isobutyryl peroxide, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, cinnamate peroxide, m-toluyl 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, cumylperoxyneodecanoate, 1,1,3,3,-Tetramethylbutyl peroxyneodecanoate, 1-cyclohexyl-1-methylethyl peroxyneodecanoate, t-hexyl peroxyneodecanoate, t-butyl peroxyneodecanoate, t-hexyl peroxypivalate, t-butyl peroxypivalate, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, 1-cyclohexyl-1-methylethyl peroxy-2-ethylhexanoate, t-hexyl peroxy-2-ethylhexanoate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxyisobutyrate, t-butyl Examples include peroxymalic acid, t-butyl peroxylaurate, t-butyl peroxy-3,5,5-trimethylhexanoate, t-butyl peroxyisopropyl monocarbonate, t-butyl peroxy-2-ethylhexyl monocarbonate, 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane, t-butyl peroxyacetate, t-hexyl peroxybenzoate, t-butyl peroxy-m-toluylbenzoate, t-butyl peroxybenzoate, bis(t-butylperoxy)isophthalate, t-butyl peroxyallyl monocarbonate, and 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone. These can be used individually or in combination of two or more. Among these organic peroxides, dicumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, and α,α'-bis(t-butylperoxy)diisopropylbenzene are preferred.

[0052] Examples of imidazole compounds include 2-ethyl-4-methylimidazole, 2-methylimidazole, 2-ethylimidazole, 2,4-dimethylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 1-vinyl-2-methylimidazole, 1-propyl-2-methylimidazole, 2-isopropylimidazole, 1-cyanomethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, and 1-cyanoethyl-2-phenylimidazole. In particular, 1-cyanoethyl-2-phenylimidazole and 2-ethyl-4-methylimidazole are preferred due to their high solubility with the composition of this embodiment. These can be used individually or in combination of two or more.

[0053] Examples of phosphine compounds include primary phosphines, secondary phosphines, and tertiary phosphines. Specific examples of primary phosphines include alkyl phosphines such as ethyl phosphine and propyl phosphine, and phenyl phosphines. Specific examples of secondary phosphines include dialkyl phosphines such as dimethyl phosphine and diethyl phosphine, and secondary phosphines such as diphenyl phosphine, methylphenyl phosphine, and ethylphenyl phosphine. Tertiary phosphines include trialkyl phosphines such as trimethylphosphine, triethylphosphine, tributylphosphine, and trioctylphosphine, tricyclohexylphosphine, triphenylphosphine, alkyldiphenylphosphine, dialkylphenylphosphine, tripenzylphosphine, tritrillylphosphine, tri-p-styrylphosphine, tris(2,6-dimethoxyphenyl)phosphine, tri-4-methylphenylphosphine, tri-4-methoxyphenylphosphine, and tri-2-cyanoethylphosphine. Among these, tertiary phosphines are preferred. These can be used individually or in combination of two or more types.

[0054] Examples of phosphonium salt compounds include compounds having tetraphenylphosphonium salts, alkyltriphenylphosphonium salts, and tetraalkylphosphonium. Specifically, these include tetraphenylphosphonium-thiocyanate, tetraphenylphosphonium-tetra-p-methylphenylborate, butyltriphenylphosphonium-thiocyanate, tetraphenylphosphonium-phthalic acid, tetrabutylphosphonium-1,2-cyclohexyldicarboxylic acid, tetrabutylphosphonium-1,2-cyclohexyldicarboxylic acid, and tetrabutylphosphonium-lauric acid. These can be used individually or in combination of two or more.

[0055] The content of the polymerization initiator is not particularly limited, but is preferably 0.1 to 10.0 parts by mass, more preferably 0.5 to 5.0 parts by mass, and even more preferably 0.7 to 3.0 parts by mass, per 100 parts by mass of maleimide resin.

[0056] (Organic solvents) The organic solvent is not particularly limited as long as it dissolves the maleimide resin. Examples of organic solvents that can be used include aromatic hydrocarbons such as benzene, toluene, xylene, and mesitylene; alcohol-based solvents such as methanol, ethanol, isopropyl alcohol, butanol, pentanol, hexanol, propanediol, and phenol; ketone-based solvents such as acetone, methyl isobutyl ketone, methyl ethyl ketone, pentanone, hexanone, cyclopentanone, cyclohexanone, isophorone, and acetophenone; cellsolves such as methyl cellsolve and ethyl cellsolve; ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, methyl propionate, and butyl formate; and glycol ether-based solvents such as ethylene glycol mono-n-butyl ether, ethylene glycol mono-iso-butyl ether, ethylene glycol mono-tert-butyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono-iso-butyl ether, triethylene glycol mono-n-butyl ether, and tetraethylene glycol mono-n-butyl ether. One or more of these can be used in combination. Among these, it is preferable to use aromatic hydrocarbons such as toluene or mesitylene, which have high solubility in maleimide resin.

[0057] The amount of organic solvent used is not particularly limited, but it is generally sufficient to use it in a range such that the non-volatile content of the composition of this embodiment is approximately 20 to 65% by mass.

[0058] The composition of this embodiment is prepared according to generally accepted methods. Examples of preparation methods include melt mixing, powder mixing, and solution mixing. In addition, other components besides the essential components of this embodiment, such as mold release agents, flame retardants, ion trapping agents, antioxidants, adhesion promoters, stress reducers, colorants, coupling agents, and inorganic fillers, may be added to the extent that they do not impair the effects of this disclosure. Furthermore, the composition of this embodiment may also contain compounds or resins other than the maleimide resins mentioned above, such as epoxy resins, (meth)acrylic resins, (meth)acrylate compounds, vinyl compounds, benzoxazine compounds, and bismaleimide compounds.

[0059] (Release agent) Release agents are added to improve the release properties from the mold. Any known release agents can be used, such as carnauba wax, rice wax, candelilla wax, polyethylene, polyethylene oxide, polypropylene, montanic acid, montan wax (an ester compound of montanic acid with saturated alcohol, 2-(2-hydroxyethylamino)ethanol, ethylene glycol, glycerin, etc.), stearic acid, stearic acid esters, and stearic acid amides. These can be used individually or in combination of two or more.

[0060] (Flame retardant) Flame retardants are added to impart flame retardancy, and all known flame retardants can be used without particular limitation. Examples of flame retardants include phosphazene compounds, silicon compounds, zinc molybdate-supported talc, zinc molybdate-supported zinc oxide, aluminum hydroxide, magnesium hydroxide, and molybdenum oxide. These can be used individually or in combination of two or more.

[0061] (Ion trapping agent) Ion trapping agents are added to liquid resin compositions to capture ionic impurities and prevent thermal and hygroscopic degradation. Any known ion trapping agent can be used, and there are no particular limitations. Examples of ion trapping agents include hydrotalcites, bismuth hydroxide compounds, and rare earth oxides. These can be used individually or in combination of two or more.

[0062] (Inorganic filler) Any known inorganic filler suitable for use in resin compositions can be used without particular limitations. Examples of inorganic fillers include aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, aluminum oxide, aluminum nitride, aluminum borate whiskers, boron nitride, silica, graphite powder, and boehmite. Among these, silica is particularly preferred due to its excellent low dielectric loss tangent. Inorganic fillers can be used individually or in combination of two or more.

[0063] The average particle size of the inorganic filler may be 50 nm or more, 100 nm or more, or 200 nm or more, and may be 10 μm or less, 5.0 μm or less, 3.0 μm or less, or 1.0 μm or less. Preferably, the average particle size of the inorganic filler is 100 nm to 10 μm or 50 nm to 5.0 μm, more preferably 100 nm to 3.0 μm, and even more preferably 200 nm to 1.0 μm. When the average particle size of the inorganic filler is within the above range, the surface roughness of the sheet can be reduced and the adhesion to the substrate such as polyimide film and copper foil can be improved.

[0064] The average particle size of the inorganic filler described above is the median diameter (d50), which represents 50% of the cumulative particle size in the volume-integrated particle size distribution. This average particle size can be measured using a laser diffraction scattering particle size distribution analyzer.

[0065] The inorganic filler is preferably surface-treated, more preferably surface-treated with a coupling agent, and more preferably surface-treated with a silane coupling agent. Surface treatment of the inorganic filler not only improves its dispersibility in organic solvents, but also further reduces the surface roughness of the sheet, thereby improving adhesion to substrates such as polyimide film and copper foil.

[0066] Examples of the coupling agents mentioned above include silane coupling agents, titanium coupling agents, and aluminum coupling agents. Examples of the silane coupling agents include methacrylicsilane, acrylicsilane, aminosilane, phenylaminosilane, imidazolesilane, phenylsilane, vinylsilane, and epoxysilane. These can be used individually or in combination of two or more.

[0067] When a resin composition contains an inorganic filler, its content may be 5-75% by mass, 5-50% by mass, 5-35% by mass, or 10-30% by mass, based on the total amount of solids (non-volatile content) of the resin composition (100% by mass). When the inorganic filler content is 75% by mass or less, the decrease in adhesiveness tends to be suppressed, and when it is 5% by mass or more, the effect of reducing the dielectric loss tangent and the effect of improving heat resistance tend to be sufficiently obtained.

[0068] <Cured product> The cured product of this embodiment is obtained by curing the composition of this embodiment. Specifically, it can be obtained by heating the composition at approximately 150 to 250°C for approximately 10 minutes to 3 hours.

[0069] The shape of the cured product in this embodiment is not particularly limited, but when used for bonding substrates, it can be in the form of a sheet with a film thickness of typically 1 to 200 μm, preferably 3 to 100 μm, and the film thickness can be adjusted as appropriate depending on the application.

[0070] <Sheet> The sheet of this embodiment comprises the composition and substrate of this embodiment. The sheet of this embodiment can be obtained, for example, by applying the composition of this embodiment to a substrate (sheet substrate) and drying it. Examples of suitable substrates include polyimide, polyimide-silica hybrid, polyamide, polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polymethyl methacrylate resin (PMMA), polystyrene resin (PSt), polycarbonate resin (PC), acrylonitrile-butadiene-styrene resin (ABS), ethylene terephthalate, phenol, phthalic acid, hydroxynaphthoic acid, and other aromatic polyester resins obtained from parahydroxybenzoic acid (so-called liquid crystal polymers; such as "Vecter" manufactured by Kuraray Co., Ltd.). Among these, polyimide film, particularly polyimide-silica hybrid film, is preferred in terms of heat resistance and dimensional stability. Furthermore, the above-mentioned substrate may be a metal such as glass, iron, aluminum, 42 alloy, or copper, or an inorganic substrate such as ITO, silicon, or silicon carbide. The thickness of the above-mentioned substrate can be set appropriately depending on the application.

[0071] <Laminate> The laminate of this embodiment is obtained by further heat-pressing a substrate onto the adhesive surface of the sheet (the layer-side surface formed using the composition of this embodiment). As the substrate, for example, organic substrates such as polyimide, polyimide-silica hybrid, polyamide, polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polymethyl methacrylate (PMMA), polystyrene resin (PSt), polycarbonate resin (PC), acrylonitrile-butadiene-styrene resin (ABS), ethylene terephthalate, phenol, phthalic acid, hydroxynaphthoic acid, and p-hydroxybenzoic acid (so-called liquid crystal polymers; such as "Vecter" manufactured by Kuraray Co., Ltd.) can be used. Alternatively, inorganic substrates such as glass, iron, aluminum, 42 alloy, copper, ITO, silicon, and silicon carbide are also preferred. The thickness of the substrate can be appropriately set depending on the application. Furthermore, the laminate may be further heat-treated.

[0072] <Printed circuit boards and printed wiring boards> The printed circuit board of this embodiment uses either the sheet described above or the laminate described above. The printed circuit board of this embodiment can be obtained, for example, by further bonding the adhesive surface of the sheet to the inorganic substrate surface of the laminate. Preferably, the printed circuit board uses a polyimide film as the organic substrate and a metal foil (especially copper foil) as the inorganic substrate. Then, a circuit board can be obtained by soft etching the metal surface of such a printed circuit board to form a circuit, and then bonding the sheet described above to it and heat pressing it. [Examples]

[0073] The present disclosure will be described in detail below with reference to examples and comparative examples, but this disclosure is not limited to these. In each example, parts and percentages are by mass unless otherwise specified. Furthermore, the measurement methods, definitions, and determination methods for the following items in the examples and comparative examples are shown below.

[0074] [Molecular weight] The molecular weight of the maleimide resin was measured by GPC (gel permeation chromatography). A sample of maleimide resin dissolved in tetrahydrofuran (THF) at a concentration of 3% by mass was injected in 50 μL into columns heated to 30°C (one GL-R420 (Hitachi High-Tech Fielding Co., Ltd.), one GL-R430 (Hitachi High-Tech Fielding Co., Ltd.), and one GL-R440 (Hitachi High-Tech Fielding Co., Ltd.)). Measurement was performed using THF as the developing solvent at a flow rate of 1.6 mL / min. An L-3350 RI detector (Hitachi, Ltd.) was used, and the number-average molecular weight (Mn) and weight-average molecular weight (Mw) were calculated from the elution time using a molecular weight / elution time curve prepared using standard polystyrene (Tosoh Corporation).

[0075] [Reaction times for imidation and maleimidation reactions] In this embodiment, the reaction time for the imidation reaction (imidation step) and the maleimidation reaction (maleimidation step) when producing maleimide resin is defined as the time from when the temperature has been raised to the reaction temperature until the time when water generated during the reaction no longer distills out visually for more than one minute.

[0076] [Presence or absence of precipitates] 100g of maleimide resin (a translucent to transparent brown varnish (liquid)) was weighed into a mayonnaise bottle and visually inspected to determine the presence or absence of precipitates. If no precipitates are present, it can be concluded that the side reactions during the synthesis of maleimide resin have been suppressed.

[0077] [Heating residue (NV)] After weighing 0.75g ± 0.25g of maleimide resin into a metal petri dish using a precision balance, it was dried in a hot air dryer at 150°C for 0.5 hours, and the NV was calculated using the following formula. NV (mass%)={(CA) / B}×100 NV: Heat residue of maleimide resin (mass %) A: Mass of an empty metal petri dish (g) B: Sample mass before drying (g) C: Metal petri dish after drying + sample mass (g)

[0078] [Acid value] 2.5 g ± 0.5 g of maleimide resin was placed in a 200 mL Erlenmeyer flask, and 30 mL of a toluene / isopropyl alcohol = 2 / 1 (vol%) mixed solvent, which had been prepared in advance using a graduated cylinder, was added and stirred until homogeneous. Then, 2 to 3 drops of 0.04 w / v% phenol red solution were added as an indicator and stirred again. Subsequently, 1 / 10 N KOH aqueous solution was added dropwise, and the acid value was calculated using the following formula. Acid value = (a × f × 5.611) / (S × NV / 100) a:1 / 10N KOH aqueous solution consumption (ml) f: Factor (-) of 1 / 10N KOH aqueous solution S: Amount of maleimide resin collected (g) NV: Heat residue of maleimide resin (mass %)

[0079] [Residual solvent volume] Using an applicator, maleimide resin was applied to a film viner (registered trademark) (PET film, manufactured by Fujimori Kogyo Co., Ltd., product name "NS14", film thickness 75 μm) to a thickness of 25 μm after drying, and then dried in a dryer at 150°C for 5 minutes. After that, the maleimide resin was peeled off the PET film, and 0.75 g ± 0.25 g was weighed into a metal petri dish using a precision balance. The mixture was then dried in a hot air dryer at 180°C for 0.5 hours, and the amount of residual solvent was measured using the following formula. Based on the measurement results, evaluation was performed according to the following criteria. Residual solvent volume (mass%) = {(ca) / b} × 100 a: Mass of an empty metal petri dish (g) b: Sample mass (g) before drying c: Metal petri dish after drying + sample mass (g) <Criteria for determining residual solvent amount> A: Less than 0.5% by mass B: 0.5% by mass or more

[0080] [Method for producing maleimide resin] (Example 1) In a 1 L flask equipped with a condenser, nitrogen inlet tube, thermocouple, and stirrer, 29.67 parts by mass of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (manufactured by Daikin Industries, Ltd., compound represented by formula (1)), 129.37 parts by mass of T-SOL 100 (manufactured by ENEOS Corporation, aromatic high-boiling point solvent, boiling point: 154-181°C), and 27.81 parts by mass of Solmix A-11 (manufactured by Nippon Alcohol Sales Co., Ltd., alcohol-based solvent, boiling point: 65°C (initial distillation)) were added. After adding the compounds, the temperature was raised to 80°C and maintained for 0.5 hours (half-esterification step). Then, 33.50 parts by mass of dimer amine (trade name "PRIAMINE 1075", manufactured by Croda Japan Co., Ltd.) was added dropwise. After the dropwise addition, 5.30 parts by mass of 4,4'-methylenedianiline (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added. After the addition, 1.71 parts by mass of an aqueous methanesulfonic acid solution (BASF, trade name "Lutropur MSA") was added. The temperature was then raised to 160°C. After raising the temperature, 40.00 parts by mass of toluene (Yamaichi Chemical Industry Co., Ltd., boiling point: 111°C) was added, and a dehydration and ring-closing reaction (imidation step) was carried out at 160°C for X hours to remove water and alcohol from the reaction solution and obtain an intermediate polyimide resin. Subsequently, the obtained polyimide resin was cooled to 130°C, 6.56 parts by mass of maleic anhydride (Fuso Chemical Industry Co., Ltd.) was added, the temperature was raised to 160°C, and a dehydration and ring-closing reaction (maleimidation step) was carried out at 160°C for Y hours to remove water from the reaction solution and obtain a maleimide resin (bismaleimide resin). The reaction times (X and Y) in the imidation step and the maleimidation step are shown in Table 1.

[0081] The obtained bismaleimide resin was placed in a separatory funnel, 500 parts by mass of pure water were added, the separatory funnel was shaken, and it was allowed to stand. After standing, the aqueous layer and the organic layer separated, and only the organic layer was recovered. The recovered organic layer was placed in a 1 L glass container equipped with a condenser, nitrogen inlet tube, thermocouple, stirrer, and vacuum pump, and the temperature was raised to 88-93°C to remove the water. Then the temperature was raised to 100°C, and the solvent was removed for 0.5 hours under a pressure of 0.1 MPa from atmospheric pressure to obtain bismaleimide resin.

[0082] (Example 2) A bismaleimide resin was obtained in the same manner as in Example 1, except that the amounts of each component were changed as shown in Table 1.

[0083] (Examples 3-4) A bismaleimide resin was obtained in the same manner as in Example 1, except that 4,4'-methylenedianiline was replaced with norbornanediamine (manufactured by Mitsui Chemicals Fine, Inc.) and the amounts of each component were changed as shown in Table 1.

[0084] (Example 5) A bismaleimide resin was obtained in the same manner as in Example 1, except that 4,4'-methylenedianiline was replaced with 1,3-diaminopropane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and the amounts of each component were changed as shown in Table 1.

[0085] (Examples 6-7) A bismaleimide resin was obtained in the same manner as in Example 1, except that 4,4'-methylenedianiline was replaced with 2-methyl-1,5-diaminopentane (manufactured by Tokyo Chemical Industry Co., Ltd.) and the amounts of each component were changed as shown in Table 1.

[0086] (Examples 8-9) A bismaleimide resin was obtained in the same manner as in Example 1, except that 4,4'-methylenedianiline was replaced with norbornanediamine (manufactured by Mitsui Chemicals Fine, Inc.), and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride was replaced with 1,3,3a,4,5,9b-hexahydro-5(tetrahydro-2,5-dioxo-3-furanyl)naphtho[1,2-C]furan-1,3-dione (manufactured by Shin Nippon Rika Co., Ltd., trade name "TDA-100", compound represented by formula (2)), and the amounts of each component were changed as shown in Table 1.

[0087] (Examples 10-11) A bismaleimide resin was obtained in the same manner as in Example 1, except that 4,4'-methylenedianiline was replaced with 2-methyl-1,5-diaminopentane (manufactured by Tokyo Chemical Industry Co., Ltd.), and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride was replaced with 1,3,3a,4,5,9b-hexahydro-5(tetrahydro-2,5-dioxo-3-furanyl)naphtho[1,2-C]furan-1,3-dione (manufactured by Shin Nippon Rika Co., Ltd., trade name "TDA-100", compound represented by formula (2)), and the amounts of each component were changed as shown in Table 1.

[0088] (Example 12) A bismaleimide resin was obtained in the same manner as in Example 1, except that 4,4'-methylenedianiline was replaced with 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene (manufactured by Tokyo Chemical Industry Co., Ltd., also known as "Bisaniline M"), and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride was replaced with 1,3,3a,4,5,9b-hexahydro-5(tetrahydro-2,5-dioxo-3-furanyl)naphtho[1,2-C]furan-1,3-dione (manufactured by Shin Nippon Rika Co., Ltd., trade name "TDA-100", compound represented by formula (2)), and the amounts of each component were changed as shown in Table 1.

[0089] (Example 13) A bismaleimide resin was obtained in the same manner as in Example 1, except that 4,4'-methylenedianiline was replaced with norbornanediamine (manufactured by Mitsui Chemicals Fine, Inc.), and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride was replaced with 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride (manufactured by ZHEJIANG ALPHARM CHEMTECH, trade name "AMC-550", compound represented by formula (3)), and the amounts of each component were changed as shown in Table 1.

[0090] (Comparative Example 1) A bismaleimide resin was obtained in the same manner as in Example 3, except that T-SOL 100 was replaced with toluene (manufactured by Yamaichi Chemical Industry Co., Ltd., boiling point: 111°C), the dehydration ring-closing reaction temperature in the imidation step and maleimidation step was changed to 110°C, and the cooling temperature after the imidation step was changed to 100°C.

[0091] (Comparative Example 2) A bismaleimide resin was obtained in the same manner as in Example 1, except that Solmix A-11 was replaced with NMP (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., boiling point: 202°C) and the amount of solvent was changed as shown in Table 1.

[0092] [Table 1]

[0093] As is clear from Table 1, the method for producing maleimide resin according to this disclosure makes it possible to produce maleimide resin with a sufficiently high molecular weight in a short time, while also reducing the acid value and preventing precipitate formation.

Claims

1. A method for producing a maleimide resin obtained by reacting a tetracarboxylic dianhydride (a1), a diamine (a2), and maleic anhydride (a3), A half-esterification step in which the tetracarboxylic dianhydride (a1) is mixed with a mixed solvent to half-esterify the tetracarboxylic dianhydride (a1), An imidization step to obtain a polyimide resin by adding the diamine (a2) to the half-esterified tetracarboxylic dianhydride (a1) and carrying out a dehydration and ring-closing reaction, A maleimide step is performed by adding the maleic anhydride (a3) ​​to the polyimide resin and carrying out a dehydration and ring-closing reaction to obtain a maleimide resin. It has, The mixed solvent contains an aromatic hydrocarbon with a boiling point of 150°C or higher and an alcohol with a boiling point of 100°C or lower. The aforementioned aromatic hydrocarbon includes solvent naphtha, A method for producing maleimide resin, wherein the diamine (a2) contains a dimer amine and a second diamine other than dimer amine.

2. The method for producing a maleimide resin according to claim 1, wherein the tetracarboxylic dianhydride (a1) contains at least one of the compounds represented by the following formulas (1) to (3). 【Chemistry 1】 【Chemistry 2】 【Transformation 3】

3. A method for producing a maleimide resin according to claim 1 or 2, wherein the mass ratio of the content of the aromatic hydrocarbon to the content of the alcohol in the mixed solvent (content of the aromatic hydrocarbon / content of the alcohol) is 2 to 6.

4. A method for producing a maleimide resin according to claim 1 or 2, wherein the content of the dimeramine in the diamine (a2) is 50 mol% or more based on the total amount of the diamine (a2).

5. A method for producing a maleimide resin according to claim 1 or 2, wherein the second diamine comprises at least one selected from the group consisting of 1,3-diaminopropane, norbornanediamine, 4,4'-methylenedianiline, and 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene.

6. A method for producing a maleimide resin according to claim 1 or 2, wherein the dimer amine comprises at least one of the compounds represented by the following general formula (4) and the compounds represented by the following general formula (5). 【Chemistry 4】 【Transformation 5】 [In equations (4) and (5), m, n, p, and q represent integers of 1 or more selected such that m+n = 6 to 17 and p+q = 8 to 19, respectively. The dashed lines indicate carbon-carbon single bonds or carbon-carbon double bonds. However, if the dashed line indicates a carbon-carbon double bond, equations (4) and (5) will 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 equations (4) and (5).]

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