Insulating coating material for coating electric wire, insulated wire, coil, and electric or electronic device

Abstract

To provide an insulating coating material for coating an electric wire, which is capable of being cured at a relatively low temperature without using a high-boiling point solvent such as N-methyl-2-pyrrolidone (NMP), and provides a cured product that is excellent in balance between heat resistance, moisture resistance, insulation property, and flexibility; and an insulated wire or the like using the same.SOLUTION: An insulating coating material for coating an electric wire includes (A) a maleimide compound having a bisphenol structure and a number average molecular weight of 5,000 to 50,000, and (B) a reaction initiator. An insulated wire includes a cured film formed from the insulating coating material for coating an electric wire.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an insulating paint for covering electric wires, and an insulated wire, a coil, and an electric / electronic device each using the insulating paint. [Background technology]

[0002] Conventionally, insulated wires having an insulating coating formed using polyamide-imide or polyimide resin insulating paint are known (Patent Documents 1 to 4). The coating is also called an enamel layer, and these materials are heat-resistant polymer resins that have excellent heat resistance, mechanical properties, hydrolysis resistance, etc.

[0003] Such paints generally use N-methyl-2-pyrrolidone (NMP) as a solvent. NMP has been widely used as an aprotic polar solvent for a long time, but because it has a high boiling point and is difficult to remove, and because it is easily exposed and toxic, regulations on NMP are becoming stricter, especially in Europe. In addition, polyamide-imide and polyimide resin insulating paints are characterized by their tendency to easily absorb moisture, which can cause problems such as the surface of the liquid turning white or the resin components precipitating or sedimenting due to the effects of moisture. Not only that, many of the materials require processing at extremely high temperatures, such as 260°C, and improvements are also considered necessary from the perspective of environmental impact.

[0004] In addition, polyamide-imide and polyimide resin insulating paints have a high dielectric constant due to the characteristics of their skeleton and the reactive residues at their ends, and the dielectric constant can also increase due to moisture absorption. Therefore, in order to improve performance, it is necessary to reduce the dielectric constant and stabilize it so that it is not dependent on the environment.

[0005] On the other hand, although not intended to solve these problems, insulating coating materials using (bis)maleimide compounds having a similar structure to polyamideimide or polyimide resins have also been reported (Patent Documents 5 to 7).

[0006] However, maleimide compounds generally tend to be low molecular weight and are therefore very hard and brittle. As a result, they are not suitable for use as insulating coating materials for coils, for example, which require flexibility. Adding materials to improve flexibility leads to a decrease in insulating properties and heat resistance.

[0007] As described above, there is still a need to develop materials that are less susceptible to moisture absorption, have a low dielectric constant, do not use high-boiling point solvents such as NMP, and yet have an excellent balance of heat resistance, insulation properties, flexibility, etc. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2013-1872 A [Patent Document 2] JP 2017-4897 A [Patent Document 3] JP 2017-130405 A [Patent Document 4] Patent No. 7257558 [Patent Document 5] JP 2012-87246 A [Patent Document 6] JP 2013-139531 A [Patent Document 7] International Publication No. 2014 / 181456 Summary of the Invention [Problem to be solved by the invention]

[0009] Therefore, an object of the present invention is to provide an insulating coating material for electric wire coating that can be cured at a relatively low temperature without using a high boiling point solvent such as NMP, and that has an excellent balance of heat resistance, moisture resistance, insulation properties, flexibility, etc. Another object of the present invention is to provide an insulated electric wire, a coil, and an electric or electronic device using this insulating coating material for electric wire coating. [Means for solving the problem]

[0010] Means of the Invention The present inventors have conducted extensive research to solve the above problems and have found that the following insulating varnish for electric wire coating can achieve the above object, thereby completing the present invention. [1] (A) a maleimide compound represented by the following formula (1) and having a number average molecular weight of 5,000 to 50,000, and (B) a reaction initiator, 4. An insulating paint for electric wire coating comprising: [ka] (In formula (1), Q 1 are independently expressed by the following formula: [ka] In the above formula, X 1 are independently expressed by the following formula: [ka] In addition, a is a number from 0 to 50, b is a number from 1 to 50, and A 1 and A 2 are each independently represented by the following formula (2) or the following formula (3): [ka] (In formula (2) and formula (3), X 2 is expressed as follows: [ka] In formula (2), R 1 are independently a hydrogen atom, a chlorine atom, or an unsubstituted or substituted aliphatic hydrocarbon group having 1 to 6 carbon atoms. [2] (B) The insulating coating material for electric wire coating according to [1], wherein the reaction initiator is an organic peroxide. [3] The insulating coating material for electric wire coating according to [2], wherein the organic peroxide has a one-hour half-life temperature of 110 to 150°C. [4] The insulating coating material for electric wire coating according to any one of [1] to [3], further comprising (C) an organic solvent having a boiling point of 135 to 200°C. [5] The wire-coating insulating coating material according to any one of [1] to [4] has at least a conductor and a cured coating of the insulating coating material for electric wire coating, The cured coating is formed directly on the surface of the conductor, or The insulated wire has a cured film formed on a coating layer of a conductor having a coating layer on its surface. [6] [5] A coil having the insulated wire described in the above. [7] [6] An electric or electronic device having the coil according to the present invention. Effect of the Invention

[0011] The insulating paint for electric wire coating of the present invention does not require the use of a high boiling point solvent such as NMP, can be cured at a relatively low temperature, and gives a cured product having an excellent balance of heat resistance, moisture resistance, insulation, flexibility, etc. In addition, this insulating paint for electric wire coating is suitably used for insulated electric wires, and the obtained insulated electric wires are useful as coils and electric / electronic devices. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present invention will now be described in more detail.

[0013] (A) Maleimide compound The component (A) is a maleimide compound represented by the following formula (1) and has a number average molecular weight of 5,000 to 50,000. [ka] (In formula (1), Q 1 are independently expressed by the following formula: [ka] In the above formula, X 1 are independently expressed by the following formula: [ka] In addition, a is a number from 0 to 50, b is a number from 1 to 50, and A 1 and A 2 are each independently represented by the following formula (2) or the following formula (3): [ka] (In formula (2) and formula (3), X 2 is expressed as follows: [ka] In formula (2), R 1 are independently a hydrogen atom, a chlorine atom, or an unsubstituted or substituted aliphatic hydrocarbon group having 1 to 6 carbon atoms.

[0014] X in formula (1) 1 From the viewpoint of availability of raw materials, -CH2- and -C(CH3)2- are preferred. In the formula (1), a is a number from 0 to 50, and preferably a number from 1 to 40. In formula (1), b is a number from 1 to 50, and preferably a number from 1 to 40. In formula (1), the sum of a and b is not limited as long as it satisfies the number average molecular weight described below, but is preferably less than 30, more preferably 25 or less, and even more preferably 20 or less. In formula (1), A 1 and A 2 each independently represents a group represented by formula (2) or formula (3).

[0015] X in formula (2) and formula (3) 2 From the viewpoint of availability of raw materials, -CH2- and -C(CH3)2- are preferred. In formula (2), R 1 are independently a hydrogen atom, a chlorine atom, or an unsubstituted or substituted aliphatic hydrocarbon group having 1 to 6 carbon atoms. R in Equation (2) 1Examples of the unsubstituted or substituted aliphatic hydrocarbon group having 1 to 6 carbon atoms represented by the formula (I) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a t-butyl group, a cyclohexyl group, and the like, and also include groups in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms such as F, Cl, Br, and the like, such as a trifluoromethyl group. 1 From the viewpoint of availability of raw materials, it is preferable that the alkyl group is a hydrogen atom or an unsubstituted or substituted aliphatic hydrocarbon group having 1 to 3 carbon atoms.

[0016] In addition, in the maleimide compound represented by formula (1), A 1 and A 2 For example, in the formula (1), A 1 When A is a group represented by the formula (2), 2 is a group represented by the above formula (3), and for example, A 1 When A is a group represented by the formula (3), 2 is preferably a group represented by the formula (2). 1 and A 2 However, this does not simultaneously result in equation (2). The bonding pattern of the units having the repeating unit number a and the units having the repeating unit number b in the maleimide compound represented by formula (1) may be a random type or a block type, but is preferably a block type from the viewpoint of the mechanical strength of the cured product.

[0017] As shown in the above formula (1), component (A) has a bisphenol structure in one molecule, is soluble in solvents other than NMP, and has excellent solvent solubility. In addition, maleimide compounds having a bisphenol structure are suitable from the viewpoint of ease of obtaining raw materials. Examples of the bisphenol structure of component (A) include bisphenol A, bisphenol F, bisphenol E, and bisphenol AF, and are not particularly limited, but bisphenol A and bisphenol F are preferred. In addition, the maleimide compound shown in the above formula (1) has a and b in the above ranges, respectively, so that the balance between the solubility in solvents and film-forming ability when uncured and the toughness and heat resistance of the obtained cured product is good.

[0018] The number average molecular weight of the maleimide compound of component (A) is 5,000 to 50,000, preferably 7,000 to 40,000, and more preferably 8,000 to 20,000. When the number average molecular weight is within this range, the maleimide compound of component (A) dissolves stably in a solvent, wettability with respect to the substrate can be ensured, and the coating before curing is less likely to crack and is of good quality. The number average molecular weight referred to in this specification refers to the number average molecular weight measured by gel permeation chromatography (GPC) under the following conditions using polystyrene as a standard substance. [GPC measurement conditions] Developing solvent: Tetrahydrofuran Flow rate: 0.35mL / min Detector: Refractive index detector (RI) Column: TSK-GEL H type (Tosoh Corporation) Column temperature: 40℃ Sample injection volume: 5 μL (0.2% by mass in THF solution)

[0019] The maleimide compound represented by formula (1) of component (A) can be produced, for example, by the method described in JP-A-2021-017485. The maleimide compound of the component (A) may use one type alone, or two or more types in combination. Furthermore, in the curable maleimide resin composition of the present invention (however, in the case where the curable maleimide resin composition contains an organic solvent (C) described below, the curable maleimide resin composition excluding the organic solvent (C)), the component (A) is preferably contained in an amount of 70 to 99.9 mass%, more preferably 80 to 99.5 mass%, and even more preferably 85 to 99.0 mass%.

[0020] (B) Reaction initiator The reaction initiator, component (B), is added to initiate and promote the crosslinking reaction of the maleimide compound, component (A), and the reaction between the maleimide group in component (A) and a reactive group that can react with the maleimide group. There are no particular limitations on the component (B) as long as it accelerates the crosslinking reaction, but in order to improve productivity, an organic peroxide is preferred as a thermal radical polymerization initiator that can easily cure in a short period of time.

[0021] Representative examples of organic peroxides include dicumyl peroxide, t-butyl peroxybenzoate, t-amyl peroxybenzoate, dibenzoyl peroxide, dilauroyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 1,1-di(t-butylperoxy)cyclohexane, di-t-butyl peroxide, dibenzoyl peroxide, and 1,6-bis(t-butylperoxycarbonyloxy)hexane.

[0022] Among these, organic peroxides having a one-hour half-life temperature of 110 to 150°C are preferred. If the one-hour half-life temperature is 110°C or higher, the peroxide will not be removed together with the organic solvent in the organic solvent removal step, and the curing reaction will not proceed too quickly and the peroxide will not cure with the organic solvent remaining, making it easier to obtain the desired properties. If the one-hour half-life temperature is 150°C or lower, there is no need to increase the curing temperature, and the peroxide can cure in a short time.

[0023] The reaction initiator is preferably blended in an amount of 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the component (A). When other thermosetting resins described later are blended in the composition, it is preferable to blend them in an amount of 0.05 to 10 parts by mass, particularly 0.1 to 5 parts by mass, per 100 parts by mass of the total of the component (A) and other thermosetting resin components. If the amount is within the range of 0.05 to 10 parts by mass per 100 parts by mass of the component (A), curing does not become very slow or fast during molding. In addition, the heat resistance and moisture resistance of the obtained cured product are well balanced. The reaction initiator may be used alone or in combination of two or more kinds.

[0024] The compositions of the present invention may also contain the following:

[0025] (C) Organic solvent The insulating coating material for electric wire coating of the present invention may further contain an organic solvent as component (C) if necessary. The type of organic solvent is not limited as long as it is capable of dissolving component (A), but an organic solvent having a boiling point of 135 to 200°C is used. If the boiling point of the organic solvent is within this range, when the insulating coating material for electric wire coating is used (after application of the insulating coating material for electric wire coating), the ease of removal of the organic solvent and the securing of workability are well balanced. In addition, since the insulating coating material for electric wire coating does not use the above-mentioned NMP, it can be said that the insulating coating material for electric wire coating has a low environmental impact. In this case, "the component (C) can dissolve the component (A)" refers to a state in which when a 25% by mass solution of the component (A) is prepared using the component (C) as a solvent, no undissolved component (A) is visually observed at 25° C. By adding an organic solvent, the composition can be suitably used for coating operations.

[0026] As the component (C), for example, a general organic solvent such as xylene, mesitylene, anisole, cyclohexanone, cyclopentanone, dimethylsulfoxide (DMSO), dimethylacetamide, etc. These may be used alone or in combination of two or more. Of these, the organic solvent of component (C) in the insulating coating material for covering electric wires of the present invention is preferably cyclohexanone, xylene or anisole.

[0027] The amount of component (C) blended is actually adjusted to the desired viscosity depending on the process, but generally it is preferably 100 to 1,000 parts by mass, and more preferably 150 to 800 parts by mass, per 100 parts by mass of component (A).

[0028] Other Additives Various additives can be blended into the insulating coating material for electric wire coating of the present invention within the range that does not impair the effects of the present invention. For example, in order to improve the resin properties, a thermosetting resin such as an acrylic resin, an organopolysiloxane, a silicone oil, a thermoplastic resin, a thermoplastic elastomer, an organic synthetic rubber, a light stabilizer, a polymerization inhibitor, a flame retardant, a pigment, or a dye may be blended. In addition, an adhesive assistant such as a silane coupling agent may be blended to improve the adhesive strength with an electric wire such as copper. Compounds having a diaminotriazine ring and benzotriazole analogues are particularly preferred for improving the adhesive strength to copper. On the other hand, although silane coupling agents are often effective, they may not be incorporated into the crosslinking depending on the curing system, and the relative dielectric constant tends to be high due to the residual epoxy group, so their use is not very preferred. In addition, an ion trapping agent or the like may be added to improve electrical properties. Furthermore, a fluorine-containing material or the like may be added to improve dielectric properties. In order to adjust the coefficient of thermal expansion (CTE), inorganic fillers such as silica may be added, but depending on the method of forming the coating film and the thickness and appearance of the film, the addition of these is often not desirable.

[0029] The insulating coating material for electric wire coating of the present invention can be produced by mixing the components (A), (B), and (C) and further other additives. The insulating coating material for electric wire coating of the present invention can be used for insulated electric wires and coils using the same, and further for electric and electronic devices including the coils. Examples of use are given below, but are not limited to these.

[0030] For example, the insulated wire can be basically produced by appropriately applying a method that is usually used for forming an insulating film on an electric wire. The insulating coating material for electric wire coating of the present invention may be directly applied to the surface of a conductor and baked to form a cured coating (enamel layer) of the insulating coating material for electric wire coating directly on the surface of the conductor, or the insulating coating material for electric wire coating of the present invention may be applied to a coating layer of a conductor having a coating layer on its surface and baked to form a cured coating (enamel layer) of the insulating coating material for electric wire coating on the coating layer of the conductor. The coating layer on the surface of the conductor is different from the cured coating of the insulating coating material for electric wire coating of the present invention, and examples of the coating layer include layers formed by coating polyimide, polyamideimide, polyetherimide, etc. Also, an extrusion layer can be formed by extrusion coating. After application, the organic solvent is removed by heating at a temperature of usually 80°C or higher, preferably 100°C or higher for 0.1 to 5 hours. Furthermore, if it is a thermosetting type, a coating with a flat surface and a strong surface can be formed by heating the electric wire coated with the coating material of the present invention at a temperature of 130°C or higher, preferably 150°C or higher for 0.5 to 10 hours. Generally, polyimide requires drying at 150°C or higher and heat curing at 220°C or higher, but the insulating coating for electric wire coating of the present invention does not require such high temperature conditions. Specifically, the organic solvent can be removed at 150°C or lower, and heat curing (film formation) can be performed at 200°C or lower. EXAMPLES

[0031] The present invention will be described in detail below with reference to examples and comparative examples. However, the present invention is not limited to the following examples. In the examples and comparative examples, "room temperature" means 25°C.

[0032] The components used in the examples and comparative examples are shown below. In the following, the number average molecular weight (Mn) is a value obtained by gel permeation chromatography (GPC) using polystyrene as a standard substance, measured under the following measurement conditions. [GPC measurement conditions] Developing solvent: Tetrahydrofuran Flow rate: 0.35mL / min Detector: Refractive index detector (RI) Column: TSK-GEL H type (Tosoh Corporation) Column temperature: 40℃ Sample injection volume: 5 μL (0.2% by mass in THF solution)

[0033] (A) Maleimide compound [Synthesis Example 1] 65.06g (0.125 mol) of 2,2-bis[4-(2,3-dicarboxyphenoxy)phenyl]propane dianhydride, 61.59g (0.150 mol) of 2,2-bis[4-(4-aminophenoxy)phenyl]propane, and 250g of anisole were added to a 1L glass four-neck flask equipped with a stirrer, a Dean-Stark tube, a cooling condenser, and a thermometer, and an amic acid was synthesized by stirring at 80°C for 3 hours. Thereafter, the temperature was raised to 150°C and stirred for 2 hours while distilling off the by-product water, producing a diamine at both ends. The flask containing the obtained solution of the diamine at both ends was cooled to room temperature, and then 4.39 g (0.055 mol) of maleic anhydride was added and stirred at 80° C. for 3 hours to synthesize maleamic acid. The temperature was then raised to 150° C. and stirred for 2 hours while distilling off the by-product water, to obtain a varnish of an aromatic bismaleimide compound represented by the following formula (A-1). The number average molecular weight (Mn) of the aromatic bismaleimide compound was 12,000. Anisole was added so that the non-volatile components of the varnish became 25% by mass. [ka] (In formula (A-1), P and Q are independently a divalent group represented by the following formula.) [ka]

[0034] [Synthesis Example 2] 65.06g (0.125 mol) of 2,2-bis[4-(2,3-dicarboxyphenoxy)phenyl]propane dianhydride, 35.26g (0.115 mol) of 4,4'-methylenebis(2,6-diethylaniline), and 250g of anisole were added to a 1L glass four-neck flask equipped with a stirrer, a Dean-Stark tube, a cooling condenser, and a thermometer, and the mixture was stirred at 80°C for 3 hours to synthesize an amic acid. The mixture was then heated to 150°C and stirred for 2 hours while distilling off the by-product water to synthesize a copolymer. After that, 7.05 g (0.015 mol) of 2,2-bis[4-(4-aminophenoxy)phenyl]propane was added to the flask containing the copolymer solution that had been cooled to room temperature, and the mixture was stirred at 80°C for 3 hours to synthesize an amic acid. The mixture was then heated to 150°C and stirred for 2 hours while distilling off the by-product water, synthesizing a diamine at both ends. The flask containing the obtained solution of diamines at both ends was cooled to room temperature, and then 1.45 g (0.015 mol) of maleic anhydride was added and stirred at 80° C. for 3 hours to synthesize maleamic acid. The mixture was then heated to 150° C. and stirred for 2 hours while distilling off the by-product water, to obtain a varnish of an aromatic bismaleimide compound represented by the following formula (A-2). The number average molecular weight (Mn) of the aromatic bismaleimide compound was 15,500. Anisole was added so that the non-volatile components of the varnish became 25% by mass. [ka]

[0035] Other Maleimide Compounds (A-3): A bismaleimide compound represented by the following formula (product name: BMI-5000, Mn: 8,000, manufactured by Designer Molecules Inc.) [ka] -C 36 H 70 - represents a hydrocarbon group derived from a dimer acid skeleton. n≒8 (average value) (A-4): 4,4'-diphenylmethane bismaleimide (BMI-1000, Mn: 410, manufactured by Daiwa Chemical Industry Co., Ltd.) (A-5): Bisphenol A diphenyl ether bismaleimide (BMI-4000, Mn: 571, manufactured by Daiwa Chemical Industry Co., Ltd.)

[0036] [Synthesis Example 3] 77.55g (0.149 mol) of 2,2-bis[4-(2,3-dicarboxyphenoxy)phenyl]propane dianhydride, 61.59g (0.150 mol) of 2,2-bis[4-(4-aminophenoxy)phenyl]propane, and 250g of anisole were added to a 1L glass four-neck flask equipped with a stirrer, a Dean-Stark tube, a cooling condenser, and a thermometer, and an amic acid was synthesized by stirring for 3 hours at 80°C. Thereafter, the temperature was raised to 150°C and stirred for 2 hours while distilling off the by-product water, producing a diamine at both ends. The flask containing the obtained solution of the diamine at both ends was cooled to room temperature, and then 0.79 g (0.010 mol) of maleic anhydride was added and stirred at 80°C for 3 hours to synthesize maleamic acid. The mixture was then heated to 150°C and stirred for 2 hours while distilling off the by-product water to obtain a varnish of an aromatic bismaleimide compound represented by the following formula (A-6). However, the viscosity was too high at room temperature to stir. The number average molecular weight (Mn) of the aromatic bismaleimide compound was 72,000, and it was very difficult to handle, so it was decided not to evaluate this bismaleimide. [ka] (In formula (A-6), P and Q are independently a divalent group represented by the following formula.) [ka]

[0037] (B) Reaction initiator (B-1): Dicumyl peroxide (trade name: Perkadox BC-FF, manufactured by Kayaku Nouryon Co., Ltd., 1-hour half-life temperature 132°C)

[0038] (C-1): Anisole (Tsujimoto Chemical Co., Ltd.)

[0039] Comparative Example Materials Polyamic acid varnish (KJR-655, manufactured by Shin-Etsu Chemical Co., Ltd., NMP-based varnish, non-volatile content 15% by mass) was used as is. Polyamideimide varnish (Viromax HR-11NN, manufactured by Toyobo Co., Ltd., NMP-based varnish, non-volatile content 15% by mass) was used as it was.

[0040] (Examples 1 to 3, Comparative Examples 1 to 8) solubility Except for the polyamic acid varnish and polyamideimide varnish used as comparative examples, resin coatings were prepared by mixing the various components (25% by mass of component (A)) according to the formulation shown in Table 1. In this case, components (A) that were completely dissolved were marked with an ◯, and components (A) that were not completely dissolved during mixing or that precipitated after being left to stand at 25°C for 12 hours were marked with an X. Evaluation of components marked with an X was terminated here.

[0041] Paint Stability Test Each paint was placed on an aluminum pan and stored in a thermo-hygrostat at 30°C and 60% RH for 60 minutes. After that, the surface of each paint was visually inspected. Paints that showed no particular change, were transparent, and no resin precipitation was observed were marked with an O, while paints that had solidified or turned white were marked with an X.

[0042] Preparation of test specimens Each coating material was applied to a 50 μm-thick release-treated PET film (product name: TN-010, manufactured by Toyobo STC Co., Ltd.) using a roller coater so that the thickness after drying would be 50 μm, and then dried under each condition. After that, the resin film was peeled off from the PET film, and a cured film was produced under each condition while applying tension using a jig. Details of each drying and curing condition are as follows. For Comparative Example 8, the film did not cure under the following curing condition A, so the film cured under the following curing condition B was subjected to the following tests. For Comparative Example 7, films were obtained under both curing conditions A and B, so the following measurements were carried out using the films obtained under each condition. Curing condition A: 110℃ 30 minutes + 180℃ 2 hours Curing condition B: 150℃ 1 hour + 200℃ 1 hour + 250℃ 4 hours Furthermore, cured films could be produced without any problems from each of the coating materials of Examples 1 to 3, and these cured films were flexible, demonstrating that the coating material of the present invention is suitable for application to materials that are themselves flexible, such as coils and electric wires.

[0043] Measurement of relative permittivity The dielectric constant at 50 Hz of the resin films of the examples and comparative examples prepared above was measured in accordance with JIS K6911:2006 (represented as dielectric constant (initial) in Table 1). The films were also stored in a thermostatic chamber at 85°C and 85% RH for 24 hours, and then measured in the same manner (represented as "dielectric constant (moisture absorption)" in Table 1). A separate film was also stored in a thermostatic chamber at 150°C for 1,000 hours, and then measured in the same manner (represented as "dielectric constant (heat treatment)" in Table 1).

[0044] Breakdown voltage measurement The dielectric breakdown voltage of the resin films of the examples and comparative examples prepared above was measured in accordance with JIS C2110-1:2016.

[0045] [Table 1]

Claims

1. (A) a maleimide compound represented by the following formula (1) and having a number average molecular weight of 5,000 to 50,000, and (B) a reaction initiator, 4. An insulating paint for electric wire coating comprising: 【Chemistry 1】 (In formula (1), Q 1 are independently expressed by the following formula: 【Chemistry 2】 In the above formula, X 1 are independently expressed by the following formula: 【Chemistry 3】 In addition, a is a number from 0 to 50, b is a number from 1 to 50, and A 1 and A 2 are each independently represented by the following formula (2) or the following formula (3): 【Chemistry 4】 (In formula (2) and formula (3), X 2 is expressed as follows: 【Chemistry 5】 In the formula (2), R 1 are independently a hydrogen atom, a chlorine atom, or an unsubstituted or substituted aliphatic hydrocarbon group having 1 to 6 carbon atoms.

2. 2. The insulating coating material for covering electric wires according to claim 1, wherein the reaction initiator (B) is an organic peroxide.

3. 3. The insulating coating material for electric wire coating according to claim 2, wherein the organic peroxide has a one-hour half-life temperature of 110 to 150°C.

4. The insulating coating material for electric wire coating according to claim 1, further comprising (C) an organic solvent having a boiling point of 135 to 200°C.

5. A wire-coating insulating material according to claim 1, The cured coating is formed directly on the surface of the conductor, or The insulated wire has a cured film formed on a coating layer of a conductor having a coating layer on its surface.

6. A coil comprising the insulated wire according to claim 5.

7. An electric / electronic device comprising the coil according to claim 6.

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