Bismaleimide compound and method for producing the same

Abstract

To provide a bismaleimide compound in which a compound itself is excellent in solubility in various solvents, a resin composition containing the same is excellent in film flexibility, and a cured product of the composition has low dielectric constant and dielectric tangent, and is high in glass transition point, excellent in heat resistance.SOLUTION: A bismaleimide compound is represented by the following formula (1). In the formula (1), A is independently a tetravalent organic group containing a ring structure, B is independently a bivalent C6-200 hydrocarbon group, Q is independently a bivalent group having a fluorine atom and an aromatic ring, W is B or Q, n is 1-100, and m is 0-100.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a bismaleimide compound and a method for producing the same.

Background Art

[0002] In recent years, the next-generation communication system called 5G (millimeter-wave band of 26 GHz to 80 GHz) has become popular, and furthermore, the development of the next-next-generation communication system called 6G has also started, aiming to achieve faster, larger-capacity, and lower-latency communication than ever. To realize these communication systems, materials for the high-frequency band of 3 to 80 GHz are required, and reduction of transmission loss is essential as a countermeasure against noise. Transmission loss is the sum of conductor loss and dielectric loss. To reduce conductor loss, it is necessary to reduce the roughness of the surface of the metal foil used. On the other hand, since dielectric loss is proportional to the product of the square root of the relative permittivity and the dielectric tangent, the development of an insulating material with excellent dielectric properties (low relative permittivity and low dielectric tangent) is required as an insulating material.

[0003] Among them, such insulating materials with excellent dielectric properties are required for substrate applications. Products called reactive polyphenylene ether resin (PPE) for rigid substrates and liquid crystal polymer (LCP) and modified polyimide (MPI) with improved properties for flexible printed circuits (FPC) have come to be used.

[0004] Although these materials have excellent characteristics, it is also true that they have many problems. For example, reactive PPE resins have excellent dielectric properties and a high glass transition temperature (Tg), but when uncured, they have poor flexibility when made into a film, so their use is limited to prepregs, etc. (e.g., Patent Documents 1 and 2). Many inventions have been disclosed regarding LCPs, such as further improving the performance of LCPs and base films and coverlay films for FPCs that use LCPs (e.g., Patent Documents 3 and 4). However, LCPs are difficult to mass-produce in a manner that meets demand, so their use is limited, and molding at high temperatures of 300°C or higher is necessary, which is a problem specific to thermoplastic resins, and an adhesive with excellent dielectric properties is required to bond copper-clad laminates. Thus, there are many areas that need to be improved.

[0005] Therefore, the use of MPIs has been considered depending on the frequency band, and many inventions related to MPIs have been disclosed (for example, Patent Documents 5 and 6). Although these MPIs have improved dielectric properties compared to current polyimides, they are thermoplastic resins like LCPs, and therefore have the same problems as LCPs. In addition, it is known that the dielectric properties become very poor due to the moisture absorption inherent to polyimides. In order to solve these problems, MPIs having a dimer diamine skeleton have also been disclosed (Patent Document 7), but they have a significantly lower glass transition temperature (Tg) than conventional MPIs and lack dimensional stability. In addition, when producing MPIs, it is essential to use aprotic polar solvents such as N-methylpyrrolidone (NMP), but the use of aprotic polar solvents is not preferable from the viewpoint of environmental conservation.

[0006] In recent years, maleimide resins have been attracting attention as materials that combine heat resistance and dielectric properties. Among maleimide resins, bismaleimide resins are common, and many low molecular weight ones are known. They have excellent heat resistance such as high Tg, but they have low solvent solubility, poor film properties in uncured products, and hard and brittle film when cured. In addition, their dielectric properties are not sufficient compared to LCP and MPI, so there is a strong demand for the development of resins that maintain heat resistance, have excellent dielectric properties, excellent solvent solubility, and film flexibility.

[0007] On the other hand, it has been reported that a maleimide compound having a skeleton substantially derived from a dimer diamine is used as a material for FPC (Patent Document 8). Although it is a resin having excellent dielectric properties and exhibiting flexible properties, its glass transition temperature is low, contrary to the characteristics of general maleimide resins, and there are problems with heat resistance.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Summary of the Invention

Problems to be Solved by the Invention

[0009] Therefore, an object of the present invention is to provide a bismaleimide compound in which the compound itself is excellent in solubility in various solvents, the film of the resin composition containing the same is excellent in flexibility, the cured product of the composition has a low relative dielectric constant and a low dielectric tangent, and a high glass transition temperature and excellent heat resistance.

Means for Solving the Problems

[0010] As a result of intensive studies to solve the above problems, the present inventors have found that the following bismaleimide compound can achieve the above object, and have completed the present invention.

[0011] <1> A bismaleimide compound represented by the following formula (1).

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Advantages of the Invention

[0012] The bismaleimide compound of the present invention is excellent in solubility in various solvents. Further, the bismaleimide compound of the present invention can provide a resin composition that is excellent in flexibility of an uncured resin film containing the same, has a low relative dielectric constant and dielectric tangent, and gives a cured product having a high glass transition temperature and excellent heat resistance.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0014] The present invention will be described in detail below.

[0015] The bismaleimide compound of the present invention is a bismaleimide compound represented by the following formula (1).

Chemical formula

[0016] In formula (1), A independently represents a tetravalent organic group containing a cyclic structure, and among them, it is preferably any of the tetravalent organic groups represented by the following structural formulas.

Chemical formula

[0017] In formula (1), Q is independently a divalent group having a fluorine atom and an aromatic ring. Specific examples of Q include one or more divalent groups having a fluorine atom and an aromatic ring represented by the following structural formula (2) or (3).

[0018]

Chemical formula

[0019] In formula (3), X1 and X2 each independently represent a divalent group selected from -O-, -C(CF3)2-, -CH2-, -CH(CH3)-, -C(CH3)2-, -S-, -CO-, -COO-, -SO2-, -NH-, -NHCO- and a single bond. Among these, -O- and -C(CF3)2- are preferred. Note that X1 and X2 may be the same or different. Also, R1, R2 and R3 each independently represent a hydrogen atom, a fluorine atom or a trifluoromethyl group. Note that R1, R2 and R3 may be the same or different, but when any of R1, R2 and R3 is a hydrogen atom, either X1 or X2 is -C(CF3)2-. Furthermore, n' is a number from 0 to 4, preferably a number from 0 to 2.

[0020] The divalent group having a fluorine atom and an aromatic ring represented by Q is a group derived from a diamine or the like having a fluorine atom and an aromatic ring in the production method described later. Examples of the diamine having a fluorine atom and an aromatic ring include 2,2'-bis(trifluoromethyl)benzidine (hereinafter also referred to as TFMB), 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (hereinafter also referred to as HFBAPP), 3,3'-bis(trifluoromethyl)benzidine, 2,2-bis(4-aminophenyl)hexafluoropropane, 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene, and 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether. Among these, TFMB and HFBAPP are preferred.

[0021] In formula (1), B is independently a divalent hydrocarbon group having 6 to 200 carbon atoms, preferably 8 to 100 carbon atoms, more preferably 10 to 50 carbon atoms. As B in formula (1), it is preferably one or more hydrocarbon groups derived from a dimer acid skeleton or divalent aliphatic hydrocarbon groups having 6 to 30 carbon atoms represented by the following structural formula. [Chemical formula] (* means a bond with the nitrogen atom in the cyclic imide group. n is 6 to 20.)

[0022] Dimer acid is a liquid dibasic acid mainly composed of a dicarboxylic acid having 36 carbon atoms, which is produced by dimerization of an unsaturated fatty acid having 18 carbon atoms using natural products such as vegetable oils as raw materials. The dimer acid skeleton is not a single skeleton but has a plurality of structures, and there are several isomers. Representative dimer acids are classified by names such as linear type (a), monocyclic type (b), aromatic ring type (c), and polycyclic type (d). In this specification, the dimer acid skeleton refers to a group derived from a dimerdiamine having a structure in which the carboxy group of such a dimer acid is substituted with a primary aminomethyl group. That is, as the hydrocarbon group derived from the dimer acid skeleton of B in formula (1), branched divalent hydrocarbon groups in which two carboxy groups are substituted with a methylene group in each of the dimer acids represented by the following (a) to (d) can be exemplified, but are not limited thereto. In addition, from the viewpoints of heat resistance and reliability of the cured product, it is more preferable that the hydrocarbon group derived from the dimer acid skeleton has a structure in which the carbon-carbon double bond in the hydrocarbon group derived from the dimer acid skeleton is reduced by a hydrogenation reaction.

[0023] [Chemical formula] As described above, since the dimer acid skeleton has a plurality of structures, in this specification, the divalent hydrocarbon group derived from the dimer acid skeleton is represented as -C 36 H 70 - in terms of its average structure.

[0024] In formula (1), W is B or Q. Which of B or Q the W will be depends on the difference in the manufacturing method described later.

[0025] In formula (1), n is from 1 to 100, preferably from 1 to 50, more preferably from 1 to 40. Also, m is from 0 to 100, preferably from 1 to 50, more preferably from 1 to 40.

[0026] The number average molecular weight (Mn) of the bismaleimide compound of the present invention is not particularly limited, but is preferably from 3,000 to 50,000, more preferably from 3,500 to 30,000, still more preferably from 4,000 to 20,000. If it is within this range, the viscosity when the bismaleimide compound of the present invention is blended into a resin composition does not become too high, and furthermore, the cured product of the resin composition has high strength.

[0027] The number average molecular weight (Mn) referred to in this specification means the number average molecular weight based on polystyrene measured by GPC under the following conditions. [GPC Measurement Conditions] Developing solvent: Tetrahydrofuran Flow rate: 0.6 mL / min Column: TSK Guardcolumn SuperH-L TSKgel SuperH4000 (6.0 mm I.D. × 15 cm × 1) TSKgel SuperH3000 (6.0 mm I.D. × 15 cm × 1) TSKgel SuperH2000 (6.0 mm I.D. × 15 cm × 2) (All are manufactured by Tosoh Corporation) Column temperature: 40 °C Sample injection volume: 20 μL (sample concentration: 0.5 mass% - tetrahydrofuran solution) Detector: Differential refractometer (RI)

[0028] In the bismaleimide compound represented by the formula (1) of the present invention, the order of each repeating unit enclosed by n and m in the formula is not limited, and the bonding mode may be alternating, block, or random, but a block is preferred.

[0029] <Method for producing bismaleimide compound> There are no particular restrictions on the method for producing the bismaleimide compound of the present invention, but it can be efficiently produced, for example, by the following two methods.

[0030] Production method 1 As one method, the following formula (8)

Chemical formula

[0031] Production method 2 As another method, the following formula (8)

Chemical formula

[0032] Although the above two production methods are shown, as a basic process, an amic acid is synthesized from a tetracarboxylic dianhydride and a diamine, and through step A (or step A') of performing a ring-closing dehydration, after step A (or step A'), a diamine different from the previous step A (or step A') is added to synthesize an amic acid, and further through step B (or step B') of performing a ring-closing dehydration, after step B (or step B'), maleic anhydride is reacted to synthesize maleamic acid, and finally through step C (or step C') of performing a ring-closing dehydration to block the molecular chain ends with maleimide groups, a bismaleimide compound can be obtained. The difference between the above two production methods is mainly only the order of the types of diamines to be introduced.

[0033] In the above two production methods, each step can be roughly classified into two types: a synthesis reaction of amic acid or maleamic acid and a ring-closing dehydration reaction, which will be described in detail below.

[0034] In step A (or step A'), first, an amic acid is synthesized by reacting a specific tetracarboxylic dianhydride with a specific diamine. Generally, this reaction proceeds at room temperature (25 °C) to 100 °C in an organic solvent (for example, a nonpolar solvent or a high-boiling aprotic polar solvent). Subsequently, the ring-closing dehydration reaction of the amic acid is carried out at 100 to 160 °C, and while removing the water by-produced by the condensation reaction from the system, the reaction proceeds. To promote the ring-closing dehydration reaction, an organic solvent (for example, a nonpolar solvent, a high-boiling aprotic polar solvent, etc.) or an acid catalyst can also be added.

[0035] Examples of the organic solvent include toluene, xylene, anisole, biphenyl, naphthalene, N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), etc. These may be used alone or in combination of two or more. Examples of the acid catalyst include sulfuric acid, methanesulfonic acid, trifluoromethanesulfonic acid, etc. These may be used alone or in combination of two or more.

[0036] The molar ratio of the tetracarboxylic dianhydride to the diamine is preferably tetracarboxylic dianhydride / diamine = 1.01 to 1.99 / 1.0, more preferably tetracarboxylic dianhydride / diamine = 1.01 to 1.80 / 1.0, and even more preferably tetracarboxylic dianhydride / diamine = 1.10 to 1.60 / 1.0. By blending in this ratio, a copolymer containing imide groups at both ends can be synthesized as a result.

[0037] In step B (or step B'), first, an amic acid is synthesized by reacting the copolymer containing imide groups at both ends obtained in step A (or step A') with a specific diamine. Generally, this reaction also proceeds at room temperature (25 °C) to 100 °C in an organic solvent (for example, a nonpolar solvent or a high-boiling aprotic polar solvent). Similarly, in the subsequent ring-closing dehydration reaction of the amic acid, after reacting under the conditions of 100 to 160 °C, it proceeds while removing the water by-produced by the condensation reaction from the system. In order to promote the ring-closing dehydration reaction, an organic solvent (for example, a non-polar solvent, a high-boiling aprotic polar solvent, etc.) or an acid catalyst can also be added.

[0038] Examples of the organic solvent include toluene, xylene, anisole, biphenyl, naphthalene, N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), etc. These may be used alone or in combination of two or more. Examples of the acid catalyst include sulfuric acid, methanesulfonic acid, trifluoromethanesulfonic acid, etc. These may be used alone or in combination of two or more.

[0039] The molar ratio of the both-end imide group-containing copolymer to the diamine is preferably 1.0:0.01 to 1.0, and more preferably 1.0:0.1 to 1.0.

[0040] In step C (or step C'), maleamic acid is synthesized by reacting the diamine having amino groups at both ends obtained in step B (or step B') with maleic anhydride at room temperature (25 °C) to 100 °C, and finally, by ring-closing dehydration while removing the water in the system by-produced under the conditions of 100 to 160 °C, the molecular chain ends can be blocked with maleimide groups to obtain the target bismaleimide compound. With such a production method, since the obtained bismaleimide compound has a block copolymer structure, the compatibility of the synthesized resin can be made uniform and improved.

[0041] The molar ratio of the diamine having amino groups at both ends to maleic anhydride is preferably 1.0:1.6 to 2.5, and more preferably 1.0:1.8 to 2.2.

[0042] The bismaleimide compound solution obtained by the method of the present invention can be washed with a catalyst or the like by a known method (for example, adding water, alcohol, etc., stirring, and allowing to stand to separate the organic solvent and the aqueous solution).

[0043] The bismaleimide compound obtained by the method of the present invention can be taken out in a varnish state, and can be purified and isolated as a solid powder by reprecipitation or the like by adding a poor solvent.

Examples

[0044] Hereinafter, examples and comparative examples will be shown to specifically explain the present invention, but the present invention is not limited to the following examples. In the examples and comparative examples, "room temperature" means 25°C.

[0045] [Example 1] Synthesis of bismaleimide compound A-1 To a 1 L four-necked glass flask equipped with a stirrer, Dean-Stark tube, cooling condenser and thermometer, add 53.37 g (0.167 mol) of TFMB, 104.10 g (0.20 mol) of 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 300 g of toluene, 200 g of N-methyl-2-pyrrolidone and 9.61 g (0.10 mol) of methanesulfonic acid, and stir at 80°C for 3 hours to synthesize an amic acid. Then, the temperature was raised to 120°C as it was, and stirred for 8 hours while distilling off the by-produced water to synthesize a block copolymer. Then, to the flask containing the block copolymer solution cooled to room temperature, add 44.53 g (0.083 mol) of Priamine-1075 (manufactured by CRODA, a dimer diamine represented by the average composition formula H2N-C 36 H 70 -NH2), and stir at 80°C for 3 hours to synthesize an amic acid. Then, the temperature was raised to 120°C as it was, and stirred for 8 hours while distilling off the by-produced water to synthesize a diamine-terminated body. The flask containing the obtained diamine solution at both ends was cooled to room temperature, and then 10.79 g (0.110 mol) of maleic anhydride was added, and maleamic acid was synthesized by stirring at room temperature for 2 hours. Then, the temperature was directly raised to 120 °C, and the mixture was stirred for 8 hours while distilling off the by-produced water to synthesize bismaleimide. The obtained solution was washed 10 times with a mixed aqueous solution of 120 g of water and isopropyl alcohol to remove impurities such as catalysts, and a varnish solution of the bismaleimide compound was obtained. Then, the water in the system was azeotropically dehydrated with toluene by distillation under reduced pressure to obtain a brown varnish solution in which the target bismaleimide was dissolved in toluene (solid content: 50% by mass). Of the obtained product 1 From the 1H-NMR spectrum and IR spectrum, it was found that the product was a bismaleimide compound having a structure represented by the following formula (A-1) (number average molecular weight: 7100). The 1H-NMR spectrum of the bismaleimide compound having a structure represented by the following formula (A-1) 1 is shown in Figure 1 for the 1H-NMR spectrum and in Figure 2 for the IR spectrum.

Chemical formula

[0046] 1 The 1H-NMR spectrum is shown in Figure 1. The assignment of each peak is shown below. 1 1H-NMR (400 MHz, CDCl3) δ = 7.97 (d, 4H), 7.80 - 7.74 (), 7.49 (s, 4H), 7.45 - 7.31 (d, 8H), 7.45 - 7.31 (d, 4H), 7.11 - 7.00 (d, 8H), 6.70 (s, 4H), 3.66 (t, 4H), 3.53 (t, 4H), 1.79 (s, 6H), 1.72 - 0.74 (m, alkyl group)

[0047] The IR spectrum is shown in Figure 2. The C=O stretching vibration of the imide carbonyl is 1707 cm-1 、A peak was observed at 1778 cm -1 , indicating that the formation of cyclic imide bonds in the product was confirmed.

[0048] [Example 2] Synthesis of Bismaleimide Compound A-2 The reaction was carried out in the same manner as in Example 1, except that 86.41 g (0.167 mol) of HFBAPP was used instead of 53.37 g (0.167 mol) of TFMB as the aromatic diamine having a fluorine atom, and a varnish solution was obtained (solid content: 50% by mass). From the 1 1H-NMR spectrum and IR spectrum of the obtained product, it was found that the product was a bismaleimide compound (number average molecular weight: 6600) having a structure represented by the following formula (A-2). [Chemical formula] -C 36 H 70 - represents a hydrocarbon group derived from a dimer acid skeleton derived from dimer diamine (Priamine-1075).

[0049] [Example 3] Synthesis of Bismaleimide Compound A-3 To a 1 L four-necked glass flask equipped with a stirrer, a Dean-Stark tube, a condenser, and a thermometer, 57.18 g (0.179 mol) of TFMB, 104.10 g (0.20 mol) of 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 300 g of toluene, 200 g of N-methyl-2-pyrrolidone, and 9.61 g (0.10 mol) of methanesulfonic acid were added, and the mixture was stirred at 80 °C for 3 hours to synthesize an amic acid. Then, the temperature was raised to 120 °C as it was, and the mixture was stirred for 8 hours while distilling off the by-produced water to synthesize a block copolymer. Then, to the flask containing the block copolymer solution cooled to room temperature, Priamine-1075 (manufactured by CRODA, average composition formula H2N-C 36 H 7038.17 g (0.071 mol) of a dimer diamine represented by -NH2 was added and stirred at 80 °C for 3 hours to synthesize an amic acid. Then, the temperature was raised to 120 °C as it was, and it was stirred for 8 hours while distilling off the by-produced water to synthesize a diamine compound with both ends. The flask containing the obtained diamine compound solution with both ends was cooled to room temperature, and then 10.79 g (0.110 mol) of maleic anhydride was added and stirred at room temperature for 2 hours to synthesize maleamic acid. Then, the temperature was raised to 120 °C as it was, and it was stirred for 8 hours while distilling off the by-produced water to synthesize bismaleimide. The obtained solution was washed 10 times with a mixed aqueous solution of 120 g of water and isopropyl alcohol to remove impurities such as catalysts, and a varnish solution of the bismaleimide compound was obtained. Then, the water in the system was subjected to azeotropic dehydration with toluene by vacuum distillation to obtain a brown varnish solution in which the target bismaleimide was dissolved in toluene (solid content: 50% by mass). Of the obtained product 1 From the 1H-NMR spectrum and IR spectrum, it was found that the product was a bismaleimide compound having a structure represented by the following formula (A-3) (number average molecular weight: 6490). [Chemical formula] -C 36 H 70 - represents a hydrocarbon group derived from a dimer acid skeleton derived from a dimer diamine (Priamine-1075).

[0050] [Example 4] Synthesis of bismaleimide compound A-4 The reaction was carried out in the same manner as in Example 3 except that 92.58 g (0.179 mol) of HFBAPP was used instead of 57.18 g (0.179 mol) of TFMB as the aromatic diamine having a fluorine atom to obtain a varnish solution (solid content: 50% by mass). Of the obtained product 1 From the 1H-NMR spectrum and IR spectrum, it was found that the product was a bismaleimide compound having a structure represented by the following formula (A-4) (number average molecular weight: 10410). [Chemical formula] -C 36 H 70 - represents a hydrocarbon group derived from a dimer acid skeleton derived from dimer diamine (Priamine-1075).

[0051] [Comparative Example 1] Synthesis of Bismaleimide Compound B-1 The reaction was carried out in the same manner as in Example 1 except that 35.38 g (0.167 mol) of 2,2'-dimethylbenzidine, an aromatic diamine without a fluorine atom, was used instead of 53.37 g (0.167 mol) of the aromatic diamine TFMB having a fluorine atom to obtain a varnish solution (solid content: 50% by mass). From the 1 1H-NMR spectrum and IR spectrum of the obtained product, it was found that the product was a bismaleimide compound (number average molecular weight: 6580) having a structure represented by the following formula (B-1). [Chemical formula] -C 36 H 70 - represents a hydrocarbon group derived from a dimer acid skeleton derived from dimer diamine (Priamine-1075).

[0052] [Comparative Example 2] Synthesis of Bismaleimide Compound B-2 The reaction was carried out in the same manner as in Example 1 except that 68.42 g (0.167 mol) of 2,2-bis[4-(4-aminophenoxy)phenyl]propane, an aromatic diamine without a fluorine atom, was used instead of 53.37 g (0.167 mol) of the aromatic diamine TFMB having a fluorine atom to obtain a varnish solution (solid content: 50% by mass). From the 1 1H-NMR spectrum and IR spectrum of the obtained product, it was found that the product was a bismaleimide compound (number average molecular weight: 7610) having a structure represented by the following formula (B-2). [Chemical formula] -C 36 H 70 - represents a hydrocarbon group derived from a dimer acid skeleton derived from dimer diamine (Priamine-1075).

[0053] Bismaleimide compound (BMI-1): Bismaleimide compound represented by the following formula (BMI-1) (SLK-2600, manufactured by Shin-Etsu Chemical Co., Ltd., for comparative example)

Chemical formula

[0054] Bismaleimide compound (BMI-2): Bismaleimide compound represented by the following formula (BMI-2) (SLK-3000, manufactured by Shin-Etsu Chemical Co., Ltd., for comparative example)

Chemical formula

[0055] Bismaleimide compound (BMI-3): 4,4'-Diphenylmethane bismaleimide represented by the following formula (BMI-1000: manufactured by Daiwa Kasei Kogyo Co., Ltd., for comparative example)

Chemical formula

[0056] <Solvent solubility of bismaleimide compounds> For bismaleimide compounds (A-1), (A-2), (A-3), (A-4), (B-1) and (B-2), and comparative bismaleimide compounds (BMI-1) to (BMI-3), the solubility in anisole, toluene, xylene and methyl ethyl ketone (MEK) was evaluated, and the evaluation results are shown in Table 1. As an evaluation method for solvent solubility, for each of the above bismaleimide compounds, a vial with each solvent added so that the non-volatile content becomes 50% by mass was left at room temperature (25 °C) for 60 days, and the content in the vial after 60 days was visually confirmed. When it was uniformly dissolved (no insoluble matter) and flowed, it was evaluated as ○, when it did not dissolve (there was insoluble matter), or when it stopped flowing, it was evaluated as ×.

[0057] <Preparation of uncured resin film and cured resin film> The bismaleimide compounds (A-1), (A-2), (A-3), (A-4), (B-1) and (B-2), and the comparative bismaleimide compounds (BMI-1) to (BMI-3) were each dissolved in toluene or anisole to prepare a toluene varnish solution or anisole varnish solution with a non-volatile content of 50% by mass. To 10 g of the solid content of this varnish solution, 0.2 g of dicumyl peroxide (Perkyl D, manufactured by NOF Corporation) was added, and it was stirred well at room temperature to obtain a varnish-like thermosetting bismaleimide resin composition. This varnish-like thermosetting bismaleimide resin composition was applied onto a support film made of a PET film with a thickness of 38 μm using a roller coater, dried at 120 °C for 10 minutes to remove the solvent, and an uncured resin film with a thickness of 50 μm was formed on the support film. Further, the uncured resin film formed on the support film was cured under the conditions of 180 °C for 2 hours in a nitrogen atmosphere to obtain a cured resin film.

[0058] <Flexibility evaluation of film> The uncured resin film formed on the support film was wound around a cylinder with a diameter of 5 mm so that the uncured resin film surface was on the outside, and the cracking and chipping state of the film were visually observed, and the evaluation was carried out according to the following criteria, and the evaluation results are shown in Table 1. ○: No cracks or chips occur in the uncured resin film. ×: Cracks and chips have occurred in a part of the uncured resin film.

[0059] <Glass transition temperature> The storage modulus (MPa) of the cured resin film was measured by DMA Q800 (manufactured by TA Instruments) in the range of 0°C to 300°C, and the temperature of the peak top obtained from the graph plotting the Tanδ values derived from the obtained storage modulus and loss modulus values was defined as the glass transition temperature (Tg). The measurement conditions were as follows: a sample with a size of 20 mm × 5 mm × 50 μm in thickness, a heating rate of 5°C / min, a multi-frequency mode, a tensile mode, and an amplitude of 15 μm. The results are shown in Table 1.

[0060] <Relative permittivity, dielectric tangent> A network analyzer (E5063-2D5 manufactured by Keysight Technologies) and a stripline (manufactured by Keycom Co., Ltd.) were connected, and the relative permittivity and dielectric tangent of the cured resin film at a frequency of 10 GHz were measured. The results are shown in Table 1.

[0061]

Table 1

[0062] From the above results, the bismaleimide compound of the present invention has good solubility in various solvents, particularly non-polar solvents such as toluene, the uncured resin film containing the bismaleimide compound has good flexibility, the cured resin film containing the bismaleimide compound has a low relative permittivity and dielectric tangent, and a high glass transition temperature. In particular, compared with the bismaleimide compounds of Comparative Example 1 and Comparative Example 2 having the same resin skeleton except that the fluorine atoms in the bismaleimide compound of the present invention are replaced by hydrogen atoms, the bismaleimide compound of the present invention has excellent solubility in solvents such as xylene and MEK, and was also found to have excellent flexibility when formed into a film.

Industrial Applicability

[0063] Since the bismaleimide compound of the present invention is excellent in flexibility when formed into a film, it has good handleability when formed into a film shape or a substrate shape, and provides a cured product having a low relative dielectric constant, a low dielectric tangent, and a high glass transition point (Tg). Further, since the bismaleimide compound of the present invention is excellent in solvent solubility, it is easy to use in combination with other resins when blended in a resin composition, and it is easy to complement each other's performance and draw out better performance. Specifically, the bismaleimide compound of the present invention is useful for applications such as multilayer printed wiring boards used in electronic devices for high-frequency bands that require an insulating material with excellent dielectric properties.

Claims

1. A bismaleimide compound represented by the following formula (1). 【Chemical Formula 1】 (In formula (1), A independently represents a tetravalent organic group containing a cyclic structure. B independently represents a divalent hydrocarbon group derived from a dimer acid skeleton. Q independently represents a divalent group having a fluorine atom and an aromatic ring. W is either B or Q. n is from 1 to 100, and m is from 1 to 40. Also, the bonding pattern of each repeating unit enclosed by n and m is a block.)

2. The bismaleimide compound according to claim 1, wherein Q in formula (1) is either of the divalent groups having a fluorine atom and an aromatic ring represented by the following structural formula (2) or (3). 【Chemical Formula 2】 【Chemical Formula 3】 (In formula (3), X 1 and X 2 are independently of each other, -O-, -C(CF 3 ) 2 -, -CH 2 -, -CH(CH 3 )-, -C(CH 3 ) 2 -, -S-, -CO-, -COO-, -SO 2 -, -NH-, -NHCO-, and a single bond, and represent a divalent group selected from them. R 1 , R 2 and R 3 each independently represent a hydrogen atom, a fluorine atom, or a trifluoromethyl group, and n' is a number from 0 to 4. Also, when any of R 1 , R 2 and R 3 is a hydrogen atom, either X 1 or X 2 is -C(CF 3 ) 2 -.)

3. The bismaleimide compound according to claim 1 or 2, wherein A in formula (1) is any of the tetravalent organic groups represented by the following structural formula. 【Chemical Formula 4】 (The bond to which the substituent in the above structural formula is not attached is bonded to the carbonyl carbon that forms the cyclic imide structure in formula (1).)

4. The bismaleimide compound according to any one of claims 1 to 3, wherein the number average molecular weight of the bismaleimide compound of the formula (1) is 3,000 to 50,000.

5. The following formula (8) 【Chemical Formula 5】 (In formula (8), A is a tetravalent organic group containing a cyclic structure.) and an acid anhydride represented by the following formula (9) H 2 N-Q-NH 2 (9) (In formula (9), Q is a divalent group having a fluorine atom and an aromatic ring.) to synthesize an amic acid with a diamine having a fluorine atom and an aromatic ring represented by, and perform a ring-closing dehydration step A; Subsequently to the step A, the reaction product obtained in the step A and the following formula (10) H 2 N-B-NH 2 (10) (In formula (10), B is a divalent hydrocarbon group derived from a dimer acid skeleton.) to synthesize an amic acid with a diamine represented by, and perform a ring-closing dehydration step B; Subsequently to the step B, maleamic acid is synthesized from the reaction product obtained in the step B and maleic anhydride, and a step C of blocking the molecular chain ends by ring-closing dehydration and a method for producing the bismaleimide compound according to any one of claims 1 to 4.

6. The following formula (8) 【Chemical Formula 6】 (In formula (8), A is a tetravalent organic group containing a cyclic structure.) and an acid anhydride represented by the following formula (10) H 2 N-B-NH 2 (10) (In formula (10), B is a divalent hydrocarbon group derived from a dimer acid skeleton.) Synthesizing an amic acid with a diamine represented by the formula and subjecting it to ring-closing dehydration to obtain step A'; Subsequently to step A', reacting the reaction product obtained in step A' with the following formula (9) H 2 N-Q-NH 2 (9) (In formula (9), Q is a divalent group having a fluorine atom and an aromatic ring.) Synthesizing an amic acid with a diamine having a fluorine atom and an aromatic ring represented by the formula and subjecting it to ring-closing dehydration to obtain step B'; Subsequently to step B', reacting the reaction product obtained in step B' with maleic anhydride to synthesize maleamic acid and subjecting it to ring-closing dehydration to block the molecular chain ends in step C' and a method for producing a bismaleimide compound according to any one of claims 1 to 4 having the above steps.

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