JP2021111448A - Enamel wire and coating material - Google Patents

Abstract

To provide an enamel wire which can suppress partial discharge even when film thickness of an insulating film is not necessarily increased, and a coating material.SOLUTION: An enamel wire includes a conductor, and an insulating film. The insulating film is composed of polyimide. In the polyimide, a ratio A1/AT that is a ratio of a molar number A1 of a first repeating unit represented by formula (1) to a total molar number AT of the molar number A1 and a molar number A2 of a second repeating unit represented by formula (2) is 0.6 or more and 1.0 or less. In the polyimide, a ratio B1/BT that is a ratio of a molar number B1 of a first group to a total molar number BT of the molar number B1 and a molar number B2 of a second group is 0.8 or more and 1.0 or less. The first group is a group represented by any one of formulae (3) to (6) in R in formula (1) or formula (2). The second group is a group represented by formula (7) in R in formula (1) or formula (2).SELECTED DRAWING: None

Description

The present disclosure relates to enamel wires and paints.

The enamel wire includes a conductor and an insulating film. As an insulating film, one made of polyimide is known (see Patent Documents 1 and 2). Known polyimides are synthesized from pyromellitic acid dianhydride (PMDA) and 4,4'-diaminodiphenyl ether (ODA).

Enamel wire is used for motors such as industrial motors. In recent years, motors have become smaller and lighter. Also, in order to improve the output, the motor is driven by a high voltage. Further, in order to improve the power performance, the motor is driven by an inverter.

Japanese Unexamined Patent Publication No. 9-106712 Japanese Unexamined Patent Publication No. 2014-49377

When the motor is driven by a high voltage and is driven by an inverter at the same time, the risk of partial discharge occurring in the enamel wire of the motor increases due to the superposition of the high voltage drive and the inverter surge. When a partial discharge occurs, the insulating film is gradually eroded, eventually resulting in poor insulation.

As a method of suppressing partial discharge, there is a method of increasing the film thickness of the insulating film. However, if the film thickness of the insulating film is increased, the occupancy rate of the conductor in the motor decreases, and it becomes difficult to increase the output of the motor.

One aspect of the present disclosure is preferably to provide an enamel wire and a coating material that can suppress partial discharge without necessarily increasing the film thickness of the insulating film.

One aspect of the present disclosure includes a conductor and a first repeating unit provided around the conductor and represented by the following formula (1) and a second repeating unit represented by the following formula (2). Alternatively, it is an enamel wire comprising an insulating film made of polyimide containing the first repeating unit.
In the polyimide, the ratio A1 / AT, which is the ratio of the number of moles A1 to the total number of moles AT of the number of moles A1 of the first repeating unit and the number of moles A2 of the second repeating unit, is 0.6 or more. It is 1.0 or less.

The polyimide has a first group represented by any of the following formulas (3) to (6) and a second group represented by the following formula (7) as R in the formula (1) or the formula (2). Includes a group or comprises the first group.
The ratio B1 / BT, which is the ratio of the number of moles B1 to the total number of moles BT of the number of moles B1 of the first group and the number of moles B2 of the second group, is 0.8 or more and 1.0 or less. ..

The enamel wire, which is one aspect of the present disclosure, can suppress partial discharge without necessarily increasing the film thickness of the insulating film.
Another aspect of the disclosure is a coating containing a polyamic acid. The polyamic acid contains a first repeating unit represented by the following formula (8) and a second repeating unit represented by the following formula (9), or contains the first repeating unit.
In the polyamic acid, the ratio C1 / CT, which is the ratio of the number of moles C1 to the total number of moles CT of the number of moles C1 of the first repeating unit and the number of moles C2 of the second repeating unit, is 0. 6 or more and 1.0 or less.

The polyamic acid is the first group represented by any of the following formulas (3) to (6) and the second group represented by the following formula (7) as R in the formula (8) or the formula (9). Or contains the first group.
The ratio D1 / DT, which is the ratio of the number of moles D1 to the total number of moles DT of the number of moles D1 of the first group and the number of moles D2 of the second group, is 0.8 or more and 1.0 or less. ..

An insulating film can be formed by using a paint which is another aspect of the present disclosure. The formed insulating film can suppress partial discharge even if the film thickness is not necessarily large.

An exemplary embodiment of the present disclosure will be described.
1. 1. Structure of Enamel Wire The enamel wire includes a conductor and an insulating film. The conductor is composed of, for example, a metal wire such as a copper wire or an aluminum wire. The cross-sectional shape of the conductor is not particularly limited. Examples of the cross-sectional shape of the conductor include a circular shape and a flat shape. The diameter of the conductor is, for example, 0.1 mm or more and 3.0 mm or less.

The insulating film is provided around the conductor. The insulating film is in contact with, for example, the outer peripheral surface of the conductor. The film thickness of the insulating film is, for example, 25 μm or more and 300 μm or less. The insulating film is made of polyimide. The polyimide contains a first repeating unit represented by the following formula (1). The polyimide may or may not contain a second repeating unit represented by the following formula (2).

The first repeating unit represented by the formula (1) is, for example, a repeating unit produced by reacting 3,3'4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) with a diamine. The second repeating unit represented by the formula (2) is, for example, a repeating unit produced by reacting pyromellitic dianhydride (PMDA) with a diamine.

In polyimide, the number of moles of the first repeating unit represented by the formula (1) is A1. In polyimide, the number of moles of the second repeating unit represented by the formula (2) is A2. In polyimide, the total number of moles of A1 and A2 is AT. The ratio of A1 to AT is defined as the ratio A1 / AT. The ratio A1 / AT is 0.6 or more and 1.0 or less.

When the ratio A1 / AT is 0.6 or more, the partial discharge start voltage (hereinafter referred to as PDIV) of the insulating film becomes large even if the film thickness of the insulating film is not necessarily large. When PDIV is large, partial discharge is unlikely to occur.

The reason why PDIV increases when the ratio A1 / AT is 0.6 or more is presumed as follows. The first repeating unit represented by the formula (1) has a higher molecular weight than the second repeating unit represented by the formula (2). Therefore, the larger the ratio A1 / AT, the lower the density of imide groups. When the density of imide groups decreases, the relative permittivity and water absorption of the insulating film decrease. As a result, the PDIV of the insulating film becomes large.

Further, when the ratio A1 / AT is 0.6 or more, the molecular structure of the polyimide becomes flexible. Since the molecular structure of the polyimide becomes flexible, the glass transition temperature Tg of the insulating film and the storage elastic modulus at a high temperature are lowered, and the thermoplasticity of the insulating film appears. Since the insulating film has thermoplasticity, the adhesion between the layers constituting the insulating film is improved.

Polyimide is a repeating unit that is neither a first repeating unit represented by the formula (1) nor a second repeating unit represented by the formula (2) (hereinafter,) as long as the characteristics of the insulating film are not impaired. Other repeating units X) may be included. The ratio of the number of moles of the other repeating unit X to AT is preferably 0.1 or less.

Other repeating units X include, for example, 3,3'4, 4'-benzophenonetetracarboxylic dianhydride (BTDA), 3,3'4,4'-diphenylsulfonetetracarboxylic dianhydride (DSDA), and the like. Examples thereof include repeating units formed by the reaction of 4,4'-oxydiphthalic dianhydride (ODPA), 4,4'-(2,2-hexafluoroisopropyridene) diphthalic acid dianhydride (6FDA) and the like with diamine. ..

The polyimide contains a first group. The first group is a group represented by any of the following formulas (3) to (6) among R in the formula (1) or the formula (2). R in the formula (1) or the formula (2) includes at least one of the groups represented by any of the following formulas (3) to (6). The polyimide may or may not contain a second group. The second group is a group represented by the following formula (7) in R in the formula (1) or the formula (2). When the polyimide contains a second group as well as a first group, the manufacturing cost of the enamel wire can be reduced without impairing the flexibility and heat resistance while the PDIV remains large.

The group represented by the formula (3) is a residue of 1,4-bis (4-aminophenoxy) benzene (TPE-Q). TPE-Q corresponds to the diamines that can be used in the synthesis of polyimide. The group represented by the formula (4) is a residue of 1,3-bis (4-aminophenoxy) benzene (TPE-R). TPE-R corresponds to diamines that can be used in the synthesis of polyimide.

The group represented by the formula (5) is a residue of 1,3-bis (3-aminophenoxy) benzene (APB). APB corresponds to the diamines that can be used in the synthesis of polyimide. The group represented by the formula (6) is a residue of 4,4'-bis (4-aminophenoxy) biphenyl (BODA). BODA corresponds to diamines that can be used in the synthesis of polyimide.

The group represented by the formula (7) is a residue of 4,4'-diaminodiphenyl ether (ODA). ODA corresponds to diamines that can be used in the synthesis of polyimide.
In polyimide, the number of moles of the first group is B1. In polyimide, the number of moles of the second group is B2. In polyimide, the total number of moles of B1 and B2 is defined as BT. The ratio of B1 to BT is defined as the ratio B1 / BT. The ratio B1 / BT is 0.8 or more and 1.0 or less.

When the ratio B1 / BT is 0.8 or more, the PDIV of the insulating film becomes large. The reason is presumed as follows. The first group has a higher molecular weight than the second group. Therefore, the larger the ratio B1 / BT, the lower the density of imide groups. When the density of imide groups decreases, the relative permittivity and water absorption of the insulating film decrease. As a result, the PDIV of the insulating film becomes large.

The R in the formula (1) or the formula (2) is, for example, a group in which all of them are represented by any of the formulas (3) to (7). Further, a part of R may be a group that does not correspond to any of the formulas (3) to (7) as long as the characteristics of the insulating film are not impaired. The ratio of the number of moles of groups that do not correspond to any of the formulas (3) to (7) to BT is preferably 0.1 or less.

The end of the polyimide may be capped. Examples of the material used for capping include a compound containing an anhydride and a compound containing an amino group. Examples of compounds containing anhydrous acid include phthalic anhydride, 4-methylphthalic anhydride, 3-methylphthalic anhydride, 1,2-naphthalic anhydride, maleic anhydride, and 2,3-naphthalenedicarboxylic acid anhydride. , Various fluorinated phthalic anhydrides, various brominated phthalic anhydrides, various chlorinated phthalic anhydrides, 2,3-anthracene dicarboxylic hydrides, 4-ethynyl phthalic anhydrides, 4-phenylethynyl phthalic anhydrides Things etc. can be mentioned. Examples of the compound containing an amino group include a compound containing one amino group.

The enamel wire of the present disclosure has a large PDIV even if the film thickness of the insulating film is not necessarily large. When the film thickness of the insulating film is 40 μm, the PDIV is preferably 970 Vp or more.
The enamel wire of the present disclosure has good flexibility. When the enamel wire of the present disclosure is stretched by 20% and then wound around a jig having a diameter twice that of the enamel wire, it is preferable that the insulating film is not cracked or cracked.

The enamel wire of the present disclosure has good heat resistance. It is preferable that the dielectric breakdown voltage of the insulating film after the heat treatment for storing the enamel wire in air at 260 ° C. for 500 hours is 70% or more of the dielectric breakdown voltage of the insulating film not subjected to the heat treatment.

The enamel wire may be provided with an adhesion layer between the conductor and the insulating film. The adhesion layer improves the adhesion between the conductor and the insulating film. The film thickness of the adhesion layer is preferably thin so as not to impair the flexibility and partial discharge resistance of the enamel wire. Partial discharge resistance means that PDIV is large. The film thickness of the adhesion layer is, for example, 1 to 10 μm.

The enamel wire may be provided with a film having a high softening temperature (hereinafter referred to as a softening resistant layer) between the conductor and the insulating film. When the softening layer is provided, the softening resistance of the enamel wire is improved. The film thickness of the softening layer can be appropriately set so as not to impair the flexibility and partial discharge resistance of the enamel wire and to improve the softening resistance of the enamel wire. The material of the softening layer is, for example, polyimide containing PMDA and ODA as main components.

The insulating film may contain additives. As additives, for example, additives that improve film strength, additives that improve surface slipperiness and wear resistance, antioxidants, additives that improve elongation characteristics, additives that lower the dielectric constant, and semiconductivity. Examples include additives for chemical conversion.

The insulating film may be, for example, an insulating film having a plurality of holes inside. Examples of the insulating film having a plurality of pores inside include an insulating film foamed by a foaming agent, an insulating film containing a plurality of hollow particles, and the like.

2. Method for manufacturing enamel wire The method for manufacturing enamel wire is, for example, a method of forming an insulating film surrounding a conductor by using a paint described later. The method of forming the insulating film is, for example, a method of repeating a process of applying a paint to a conductor and baking it. The baking temperature is, for example, 300 to 500 ° C. The baking time in one step is, for example, 1 to 2 minutes. The number of times the process is repeated is, for example, 10 to 50 times. The more the process is repeated, the larger the film thickness of the insulating film.

The method for producing the enamel wire is not limited to the coating method, and may be a method of molding an insulating film at a high temperature. When the enamel wire has an adhesive layer or a softening resistant layer, an insulating film is formed after forming the adhesive layer or the softening resistant layer.

3. 3. Composition of paint The paint is, for example, an insulating paint. The paint is, for example, a paint for enamel wire. The paint contains a polyamic acid. The polyamic acid contains a first repeating unit represented by the following formula (8). The polyamic acid may or may not contain a second repeating unit represented by the following formula (9).

In polyamic acid, the number of moles of the first repeating unit represented by the formula (8) is defined as C1. In polyamic acid, the number of moles of the second repeating unit represented by the formula (9) is defined as C2. In polyamic acid, the total number of moles of C1 and C2 is defined as CT. The ratio of C1 to CT is defined as the ratio C1 / CT. The ratio C1 / CT is 0.6 or more and 1.0 or less.

When the ratio C1 / CT is 0.6 or more, the PDIV of the insulating film becomes large even if the film thickness of the insulating film formed by using the paint is not necessarily large.
The reason why PDIV increases when the ratio C1 / CT is 0.6 or more is presumed as follows. The first repeating unit represented by the formula (8) has a higher molecular weight than the second repeating unit represented by the formula (9). Therefore, the larger the ratio C1 / CT, the lower the density of imide groups. When the density of imide groups decreases, the relative permittivity and water absorption of the insulating film decrease. As a result, the PDIV of the insulating film becomes large.

Further, when the ratio C1 / CT is 0.6 or more, the molecular structure of the polyimide contained in the insulating film formed by using the paint becomes flexible. Since the molecular structure of the polyimide becomes flexible, the glass transition temperature Tg of the insulating film and the storage elastic modulus at a high temperature are lowered, and the thermoplasticity of the insulating film appears. Since the insulating film has thermoplasticity, the adhesion between the layers constituting the insulating film is improved.

The polyamic acid is either the first repeating unit represented by the formula (8) or the second repeating unit represented by the formula (9) as long as the characteristics of the insulating film formed by using the paint are not impaired. It may also include a repeating unit that is not (hereinafter referred to as another repeating unit Y). The ratio of the number of moles of the other repeating unit Y to CT is preferably 0.1 or less.

Examples of the other repeating unit Y include a repeating unit formed by the reaction of BTDA, DSDA, ODPA, 6FDA and the like with a diamine.
The polyamic acid contains a first group. The first group is a group represented by any of the following formulas (3) to (6) among R in the formula (8) or the formula (9). R in the formula (8) or the formula (9) includes at least one of the groups represented by any of the following formulas (3) to (6). The polyamic acid may or may not contain a second group. The second group is a group represented by the following formula (7) in R in the formula (1) or the formula (2).
When the polyamic acid contains a second group together with the first group, the production cost of the enamel wire can be reduced without impairing the flexibility and heat resistance while the PDIV remains large.

The group represented by the formula (3) is a residue of TPE-Q. TPE-Q corresponds to the diamines that can be used in the synthesis of polyamic acids. The group represented by the formula (4) is a residue of TPE-R. TPE-R corresponds to the diamines that can be used in the synthesis of polyamic acids. The group represented by the formula (5) is a residue of APB. APB corresponds to the diamines that can be used in the synthesis of polyamic acids. The group represented by the formula (6) is a residue of BODA. BODA corresponds to the diamines that can be used in the synthesis of polyamic acids. The group represented by the formula (7) is a residue of ODA. ODA corresponds to diamines that can be used in the synthesis of polyamic acids.

In polyamic acids, the number of moles of the first group is D1. In polyamic acid, the number of moles of the second group is D2. In polyamic acid, the total number of moles of D1 and D2 is defined as DT. The ratio of D1 to DT is defined as the ratio D1 / DT. The ratio D1 / DT is 0.8 or more and 1.0 or less.

When the ratio D1 / DT is 0.8 or more, the PDIV of the insulating film formed by using the paint becomes large. The reason is presumed as follows. The first group has a higher molecular weight than the second group. Therefore, the larger the ratio D1 / DT, the lower the density of imide groups. When the density of imide groups decreases, the relative permittivity and water absorption of the insulating film decrease. As a result, the PDIV of the insulating film becomes large.

The R in the formula (8) or the formula (9) is, for example, a group in which all of them are represented by any of the formulas (3) to (7). Further, a part of R may be a group that does not correspond to any of the formulas (3) to (7) as long as the characteristics of the insulating film are not impaired. The ratio of the number of moles of groups that do not correspond to any of the formulas (3) to (7) to DT is preferably 0.1 or less.

The ends of the polyamic acid may be capped. Examples of the material used for capping include the same materials as those used for polyimide capping.
As paint solvents, for example, N-methyl-2-pyrrolidone (NMP), γ-butyrolactone, N, N-dimethylacetamide (DMAC), N, N-dimethylformamide (DMF), dimethylimidazolidinone (DMI), Cyclohexanone, methylcyclohexanone, hydrocarbons and the like can be mentioned. Two or more of the above-mentioned solvents may be used in combination as long as the characteristics of the coating material are not impaired. The solvent of the paint is, for example, a solvent for synthesizing a polyamic acid.

The paint may contain additives. As additives, for example, additives that improve film strength, additives that improve surface slipperiness and wear resistance, antioxidants, additives that improve elongation characteristics, additives that lower the dielectric constant, and semiconductivity. Examples include additives for chemical conversion.

The paint may contain, for example, a foaming agent, hollow particles and the like. When the paint contains a foaming agent, hollow particles, or the like, an insulating film having a plurality of pores can be formed inside.
4. Method for Producing Paint Polyamic acid can be produced, for example, by reacting acid dianhydride with diamine. The molar ratio of acid dianhydride to diamine is, for example, 100: 100. Further, the molar ratio of the acid dianhydride to the diamine may deviate from 100: 100, for example, as long as the characteristics of the insulating film are not impaired. The characteristic of the insulating film is, for example, flexibility.

For example, 10.0 to 105.0 mol of diamine can be blended with 100 mol of acid dianhydride. Further, for example, 10.0 to 105.0 mol of acid dianhydride can be blended with 100 mol of diamine. By adding one of the acid dianhydride and the diamine in excess to the other, the molecular weight of the polyamic acid can be controlled to be small. When the molecular weight of the polyamic acid is reduced, the viscosity of the paint is reduced and the workability in painting is improved.

The temperature at which the polyamic acid is synthesized can be appropriately adjusted as long as the characteristics of the produced polyamic acid are not impaired. The temperature at which the polyamic acid is synthesized is, for example, in the range of 0 to 100 ° C. After synthesizing the polyamic acid, the viscosity of the paint may be adjusted by heating the paint to about 50 to 100 ° C. and stirring the paint. The adjusted viscosity of the paint is, for example, 1 to 5 Pa · s.

5. Example (5-1) Production of Paint The paints of Examples 1 to 7 and the paints of Comparative Examples 1 to 5 were produced. The method for producing the coating material was to first dissolve the diamine in NMP, then dissolve the acid dianhydride, and then stir at room temperature for 12 hours. At this time, the mass of NMP was 80 parts by mass, and the total mass of diamine and acid dianhydride was 20 parts by mass. As a result of stirring, a paint containing a polyamic acid was obtained. The obtained paint was diluted to improve the workability of painting, and the viscosity was adjusted. The adjusted viscosity of the paint was 2-3 Pas / sec.

In each Example and each Comparative Example, the type and amount of diamine and the type and amount of acid dianhydride were as shown in Table 1. The amount of diamine in Table 1 is the molar ratio to the total number of moles of all diamines. The amount of acid dianhydride in Table 1 is the molar ratio to the total number of moles of all acid dianhydrides.

However, more specifically, in each Example and each Comparative Example, the number of moles of one of the acid dianhydrides or diamines was increased by 0.1 to 5% as compared with the number of moles of the other. The reason for this is to prevent the paint from becoming excessively viscous. The BAPP in Table 1 is 2,2-bis [4- (4-aminophenoxy) phenyl] propane.

PMDA is an acid dianhydride that produces a second repeating unit represented by the formula (2) and a second repeating unit represented by the formula (9). The number of moles of PMDA is equal to the number of moles of the second repeating unit represented by the formula (2) and equal to the number of moles of the second repeating unit represented by the formula (9). s-BPDA is an acid dianhydride that gives rise to the first repeating unit represented by the formula (1) and the first repeating unit represented by the formula (8). The number of moles of s-BPDA is equal to the number of moles of the first repeating unit represented by the formula (1) and equal to the number of moles of the first repeating unit represented by the formula (8).

ODA is a diamine that gives rise to a second group represented by formula (7). BODA is a diamine that gives rise to the first group represented by the formula (6). TPE-R is a diamine that gives rise to the first group represented by the formula (4).
(5-2) Production of Enamel Wire Using the paints of each Example and each Comparative Example, an enamel wire was produced by the following method. A copper wire having a diameter of 0.8 mm was prepared. This copper wire corresponds to the conductor. The process of applying the paint to the copper wire and baking it was repeated. A painting furnace was used for baking. The baking temperature was 450 ° C. The baking time in one step was 90 seconds. The number of times the above steps were repeated was 15 times. As a result, an insulating film was formed around the copper wire, and an enamel wire was obtained. The film thickness of the insulating film was 40 μm.
(5-3) Evaluation of enamel wire
(i) Measurement of PDIV PDIV was measured by the following method for each of the enamel wires of each Example and each Comparative Example. A plurality of cut pieces having a length of 500 mm were cut out from the enamel wire. Twisted pair was made from two pieces. Ten twisted pairs were created.

Of the twisted pair, the insulating film of a portion having a length of 10 mm including the end portion (hereinafter referred to as a terminal processing portion) was removed. An electrode was connected to the terminal processing unit. A voltage of 50 Hz was applied to the twisted pair in an atmosphere of 25 ° C. and a humidity of 50%, and the voltage was increased at 10 to 30 V / s. The voltage when 10 pC discharge was generated 50 times per second in twisted pair was defined as PDIV. This operation was repeated three times for one twisted pair, and the average value of the three measurements was taken as the PDIV of the twisted pair. The average value of PDIV of 10 twisted pairs was calculated. The measurement results of PDIV are shown in Table 1.

When the film thickness of the insulating film is 40 μm and the PDIV is 970 Vp or more, the partial discharge resistance is considered to be good. “◯” in Table 1 indicates that the partial discharge resistance is good.
(ii) Evaluation of flexibility The flexibility of each of the enamel wires of each example and each comparative example was evaluated by the following method. After extending the enamel wire by 20%, the enamel wire was wound around a jig having a diameter twice that of the enamel wire. Next, the surface of the insulating film was observed with a microscope. If there were no defects such as cracks and cracks on the surface of the insulating film, it was judged that the flexibility was good. If there are defects such as cracks and cracks on the surface of the insulating film, it is judged that the flexibility is poor. The evaluation results are shown in Table 1. “◯” in Table 1 indicates that the flexibility is good.
(iii) Evaluation of heat resistance The heat resistance of each of the enamel wires of each Example and each Comparative Example was evaluated by the following method. A heat treatment was performed in which the enamel wire was stored in air at 260 ° C. for 500 hours. A constant temperature bath was used for the heat treatment. If the dielectric breakdown voltage of the insulating film after the heat treatment is 70% or more of the dielectric breakdown voltage of the insulating film not subjected to the heat treatment, it is judged that the heat resistance is good. If the dielectric breakdown voltage of the insulating film after the heat treatment is less than 70% of the dielectric breakdown voltage of the insulating film not subjected to the heat treatment, it is judged that the heat resistance is poor. The evaluation results are shown in Table 1. In Table 1, "◯" indicates that the heat resistance is good, and "x" indicates that the heat resistance is poor.
(iv) Summary of evaluation results In the enamel wire of each example, PDIV was large even if the film thickness of the insulating film was not large. In addition, the enamel wire of each example had good flexibility and heat resistance.

PDIV was low in the enamel wires of Comparative Examples 1 to 4. The enamel wire of Comparative Example 5 had poor heat resistance. It is presumed that the reason why the heat resistance is poor is that BAPP having an aliphatic group is used as a raw material for the paint, so that the insulating film deteriorates at a high temperature and the insulating property of the insulating film deteriorates.

6. Other Embodiments Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and can be implemented in various modifications.

(1) The function of one component in each of the above embodiments may be shared by a plurality of components, or the function of the plurality of components may be exerted by one component. Further, a part of the configuration of each of the above embodiments may be omitted. In addition, at least a part of the configuration of each of the above embodiments may be added or replaced with respect to the configuration of the other embodiment.

(2) In addition to the above-mentioned enamel wire, the present disclosure can be realized in various forms such as a system including the enamel wire as a component, a method for manufacturing the enamel wire, and a method for manufacturing a paint.

Claims (5)

With the conductor
A polyimide provided around the conductor and containing a first repeating unit represented by the following formula (1) and a second repeating unit represented by the following formula (2) or containing the first repeating unit. Insulation film consisting of
Enamel wire with
In the polyimide, the ratio A1 / AT, which is the ratio of the number of moles A1 to the total number of moles AT of the number of moles A1 of the first repeating unit and the number of moles A2 of the second repeating unit, is 0.6 or more. 1.0 or less
The polyimide has a first group represented by any of the following formulas (3) to (6) and a second group represented by the following formula (7) as R in the formula (1) or the formula (2). Contains a group or contains the first group
The ratio B1 / BT, which is the ratio of the number of moles B1 to the total number of moles BT of the number of moles B1 of the first group and the number of moles B2 of the second group, is 0.8 or more and 1.0 or less. Enamel wire.

The enamel wire according to claim 1.
An enamel wire having a partial discharge start voltage of 970 Vp or more when the film thickness of the insulating film is 40 μm. The enamel wire according to claim 1 or 2.
An enamel wire in which cracks and cracks do not occur in the insulating film when the enamel wire is wound around a jig having a diameter twice that of the enamel wire after the enamel wire is stretched by 20%. The enamel wire according to any one of claims 1 to 3.
The breakdown voltage of the insulating film after the heat treatment for storing the enamel wire in air at 260 ° C. for 500 hours is 70% or more of the breakdown voltage of the insulating coating not subjected to the heat treatment. .. A paint containing polyamic acid
The polyamic acid contains a first repeating unit represented by the following formula (8) and a second repeating unit represented by the following formula (9), or contains the first repeating unit.
In the polyamic acid, the ratio C1 / CT, which is the ratio of the number of moles C1 to the total number of moles CT of the number of moles C1 of the first repeating unit and the number of moles C2 of the second repeating unit, is 0. 6 or more and 1.0 or less,
The polyamic acid is the first group represented by any of the following formulas (3) to (6) and the second group represented by the following formula (7) as R in the formula (8) or the formula (9). Or contains the first group of
The ratio D1 / DT, which is the ratio of the number of moles D1 to the total number of moles DT of the number of moles D1 of the first group and the number of moles D2 of the second group, is 0.8 or more and 1.0 or less. paint.