WO2019102800A1 - Insulated wire - Google Patents

Abstract

An insulated wire according to the present disclosure is provided with a linear metal conductor and an insulating layer that is superposed on the outer circumferential surface of the metal conductor. The insulating layer has a multilayer structure that is composed of two or more insulating films; at least one of the two or more insulating films is a polyimide film that is mainly composed of a polyimide; and the insulating layer contains two or more residual solvents that have different boiling points.

Description

Insulated wire

The present disclosure relates to an insulated wire.

This application claims the priority based on Japanese Patent Application No. 2017-227118 filed on Nov. 27, 2017, and incorporates all the contents described in the aforementioned Japanese application.

Excellent heat resistance and durability are required of the insulated wire used for the production of coils for motors and the like. Since a general insulated wire is provided with a resin insulating layer on the outer peripheral surface side of the linear metal conductor, the resin insulating layer has not only insulation but also adhesion to the metal conductor, heat resistance and durability. Sex is required.

Polyimide, polyamide imide, polyester imide, etc. are used as resin which forms an insulating layer of an insulated wire. Among these resins, polyimide is most suitably used as a material for forming an insulating layer of an insulated wire having high required performance because polyimide is the most excellent in heat resistance and high in durability and solvent resistance.

On the other hand, as a method of forming the insulating layer of the insulated wire, for example, a method is known in which a varnish for forming an insulating film is applied to the outer peripheral surface of a metal conductor and then the varnish is baked (Patent Document 1). In this method, an insulating film having a thickness of about several μm is formed by one baking step. And the application process and baking process of a varnish are implemented in multiple times until the insulating layer of sufficient thickness is formed.

In the insulated wire described in Patent Document 1, the outermost layer of the insulating layer is a polyimide layer, and the resin constituting the insulating layers other than the outermost layer is a polyamide imide or the like, whereby the insulating layer under the polyimide layer and the polyimide layer is formed. Improve adhesion with

JP 2012-243614 A

An insulated wire according to an aspect of the present invention is an insulated wire including a linear metal conductor and an insulating layer laminated on the outer peripheral surface side of the metal conductor, and the insulating layer is an insulating film having two or more insulating films. And at least one of the two or more insulating films is a polyimide film containing polyimide as a main component, and the insulating layer contains two or more types of residual solvents having different boiling points.

An insulated wire according to another aspect of the present invention is an insulated wire including a linear metal conductor and an insulating layer laminated on the outer peripheral surface side of the metal conductor, wherein the insulating layer is two or more insulating layers. It has a laminated structure of films, and at least one of the two or more insulating films is a polyimide film mainly composed of polyimide, and the insulating layer contains two or more kinds of residual solvents having different boiling points, The content of each of the residual solvents in the insulating layer is 0.001% by mass or more and less than 0.1% by mass, and the total content of the two or more types of residual solvents in the insulating layer is 0.002% by mass More than 0.1% by mass or less, and the above-mentioned polyimide in the above-mentioned polyimide film is derived from a structural unit derived from pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride Structure Structural unit derived from 4,4′-diaminodiphenyl ether and structural unit derived from 4,4′-bis (4-aminophenoxy) biphenyl. At least one of

FIG. 1 is a schematic partial cross-sectional view showing an insulated wire according to an embodiment of the present invention.

[Problems to be solved by the present disclosure]
Polyimide having high solvent resistance has low affinity with the varnish. Therefore, even if a varnish containing polyimide is simply applied to the surface of the polyimide film, the adhesion between the two polyimide films after baking is not sufficiently improved. When the adhesion between the insulation films forming the insulation layer is low, the insulation film may be peeled off when the insulated wire provided with the insulation layer is subjected to winding processing.

Based on the circumstances as described above, the present disclosure aims to provide an insulated wire capable of improving the adhesion between insulating films forming the insulating layer.

[Effect of the present disclosure]
According to the present disclosure, it is possible to provide an insulated wire capable of improving the adhesion between insulating films forming the insulating layer.

Description of the embodiment of the present invention
First, the embodiments of the present invention will be listed and described.

An insulated wire according to an aspect of the present invention is an insulated wire including a linear metal conductor and an insulating layer laminated on the outer peripheral surface side of the metal conductor, and the insulating layer is an insulating film having two or more insulating films. And at least one of the two or more insulating films is a polyimide film containing polyimide as a main component, and the insulating layer contains two or more types of residual solvents having different boiling points.

In the insulated wire, at least one of the two or more insulating films forming the laminated structure is a polyimide film mainly composed of polyimide, and the insulating layer containing this polyimide film contains two or more kinds of residual solvents having different boiling points. Do. When the varnish for forming the polyimide film contains two or more solvents having different boiling points, rapid drying of the varnish is suppressed at the time of formation of the polyimide film, so that the surface of the polyimide film tends to be smooth. In addition, since the polyimide film contains two or more types of residual solvents, the affinity with other varnishes for forming an insulating film is improved. Therefore, the said insulated wire can improve the adhesiveness between the insulating film which forms the insulating layer containing a polyimide film by providing the insulating layer containing 2 or more types of residual solvents in which boiling points differ. Here, the main component refers to the component with the highest content, and usually represents a component of 50% by mass or more.

The content of each of the residual solvents in the insulating layer is 0.001% by mass or more and less than 0.1% by mass, and the total content of the two or more types of residual solvents in the insulating layer is 0.002% by mass It is preferable that the content be 0.1% by mass or less. Thereby, the said insulated wire can improve the adhesiveness between the insulation films which form an insulation layer appropriately.

When the polyimide in the polyimide film contains at least one of a structural unit derived from pyromellitic dianhydride and a structural unit derived from 3,3 ′, 4,4′-biphenyltetracarboxylic acid dianhydride Good. By using at least one of pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride as the tetracarboxylic acid dianhydride serving as a raw material of the polyimide, the insulated wire can be used. The heat resistance of the polyimide film can be improved.

The polyimide in the polyimide film may include at least one of a structural unit derived from 4,4'-diaminodiphenyl ether and a structural unit derived from 4,4'-bis (4-aminophenoxy) biphenyl. The said insulated wire improves the heat resistance of a polyimide membrane by using at least any one of 4,4'- diaminodiphenyl ether and 4,4'- bis (4-amino phenoxy) biphenyl as diamine used as a raw material of polyimide. be able to.

An intermediate insulating layer laminated between the metal conductor and the insulating layer is further provided, and the intermediate insulating layer is formed of a resin composition containing a thermosetting resin, a thermoplastic resin, or a mixture thereof as a main component. Good to have. It is because it can contribute to the improvement of the heat resistance of the above-mentioned middle insulating layer. From the viewpoint of improving the heat resistance, it is more preferable that the resin composition contains polyamideimide as a main component.

The average thickness of the intermediate insulating layer is preferably 5 μm or more and 250 μm or less. While maintaining the strength of the intermediate insulating layer, it is possible to prevent the decrease in space factor of the coil formed of the insulated wire.

Details of the Embodiment of the Present Invention
Hereinafter, the insulated wire concerning the embodiment of the present invention is explained, referring to drawings suitably.

[Insulated wire]
The insulated wire 1 of FIG. 1 includes a linear metal conductor 2 and an insulating layer 3 laminated on the outer peripheral surface side of the metal conductor 2. The insulated wire 1 further includes an intermediate insulating layer 4 stacked between the metal conductor 2 and the insulating layer 3.

<Metal conductor>
The metal conductor 2 is a metal linear body responsible for the electrical conduction of the insulated wire 1 and is formed in a circular shape in a cross sectional view. The cross-sectional shape of the metal conductor 2 is not limited to a circle, and may be, for example, a rectangle, a rounded rectangle, or an ellipse. Moreover, the metal conductor 2 may be a single linear body, or may be a stranded wire body in which a plurality of thin wires are twisted.

As a material of the metal conductor 2, for example, a metal such as copper, aluminum, nickel, silver, iron or the like or an alloy thereof is used, but it is preferable to use copper or aluminum from the viewpoint of conductivity and processability. In addition, the metal conductor 2 may have a multilayer structure in which a coating made of another metal is laminated on the outer peripheral surface of the linear body made of metal.

As a lower limit of the average cross-sectional area of the metal conductor 2, 0.01 mm ² is preferable, and 0.1 mm ² is more preferable. On the other hand, preferably 100 mm ² as the upper limit of the average cross-sectional area of the metal conductor 2, 50 mm ² is more preferable. If the average cross-sectional area of the metal conductor 2 does not reach the above lower limit, the electrical resistance of the metal conductor 2 may increase, and heat generation may occur when the insulated wire 1 is used. On the contrary, when the average cross-sectional area of the metal conductor 2 exceeds the above-mentioned upper limit, the cross-sectional area of the insulated wire 1 becomes large, and there is a possibility that the coil etc. manufactured using the insulated wire 1 may become large. Here, the average cross-sectional area indicates an average value of cross-sectional areas in any five cross-sectional views.

<Intermediate insulating layer>
The intermediate insulating layer 4 is a covering layer covering the outer periphery of the metal conductor 2 and has an insulating property. The intermediate insulating layer 4 is laminated on the outer peripheral surface of the metal conductor 2 as shown in FIG. 1, but may be laminated on the outer peripheral surface side of the metal conductor 2, and the metal conductor 2 and the intermediate insulating layer 4 Another layer may be laminated between the layers.

The intermediate insulating layer 4 is formed of a resin composition containing a thermosetting resin, a thermoplastic resin, or a mixture thereof as a main component. As a resin composition, polyamide imide, polyester imide, polyether imide, H type polyester, polyester imide, polyurethane etc. are used, for example. Among these resin compositions, it is preferable to use polyamide imide from the viewpoint of heat resistance improvement. A hardening agent may be added to the intermediate insulating layer 4 as necessary.

The lower limit of the average thickness of the intermediate insulating layer 4 is preferably 5 μm, more preferably 10 μm, and still more preferably 15 μm. On the other hand, the upper limit of the average thickness of the intermediate insulating layer 4 is preferably 250 μm, more preferably 200 μm, and still more preferably 150 μm. If the average thickness of the intermediate insulating layer 4 is less than the above lower limit, the strength of the intermediate insulating layer 4 may be insufficient. Conversely, when the average thickness of the intermediate insulating layer 4 exceeds the upper limit, the space factor of the coil formed of the insulated wire 1 may be reduced. Here, the average thickness indicates an average value of any five thicknesses in one cross-sectional view.

The intermediate insulating layer 4 is formed by applying a varnish obtained by dissolving the above-described resin composition in a volatile solvent on the outer peripheral surface of the metal conductor 2 and then evaporating the solvent by heating and curing the resin composition. Be done.

<Insulating layer>
The insulating layer 3 is a covering layer covering the outer periphery of the intermediate insulating layer 4 and has an insulating property. Although the insulating layer 3 is laminated on the outer peripheral surface of the intermediate insulating layer 4 in FIG. 1, it may be laminated on the outer peripheral surface side of the metal conductor 2, and the other insulating layer 3 may be interposed between the intermediate insulating layer 4 and the insulating layer 3. Layers may be stacked.

The insulating layer 3 has a laminated structure of two or more insulating films. Specifically, as shown in FIG. 1, the insulating layer 3 is an insulating film 3 c laminated on the outer peripheral surface of the intermediate insulating layer 4, an insulating film 3 b laminated on the outer peripheral surface of the insulating film 3 c, and an insulating film And an insulating film 3a to be laminated on the outer peripheral surface of 3b, and these insulating films form a laminated structure. In addition, the insulating layer 3 should just have a laminated structure of two or more insulating films, and is not limited to what has a laminated structure of three insulating films.

The lower limit of the average thickness of the insulating layer 3 is preferably 5 μm, more preferably 10 μm, and still more preferably 15 μm. On the other hand, the upper limit of the average thickness of the insulating layer 3 is preferably 250 μm, more preferably 200 μm, and still more preferably 150 μm. If the average thickness of the insulating layer 3 is less than the above lower limit, the strength of the insulating layer 3 may be insufficient. Conversely, when the average thickness of the insulating layer 3 exceeds the upper limit, the space factor of the coil formed of the insulated wire 1 may be reduced.

(Insulating film)
The insulating film 3a, the insulating film 3b, and the insulating film 3c are polyimide films containing polyimide as a main component, and contain two or more types of residual solvents having different boiling points. The entire insulating film forming the insulating layer 3 does not have to be a polyimide film, and at least one of the two or more insulating films contains polyimide as a main component, and contains two or more types of residual solvents having different boiling points. It may be a film.

As a minimum of content of polyimide in polyimide membrane, 50 mass% is preferred, 55 mass% is more preferred, and 60 mass% is still more preferred. On the other hand, the upper limit of the content may be less than 100% by mass, but the upper limit of the content is preferably 98% by mass, and more preferably 95% by mass. There exists a possibility that a polyimide membrane may not have sufficient heat resistance as the said content is less than the said minimum. Conversely, when the content exceeds the preferable upper limit, it is difficult to add other additives to the polyimide film, and there is a possibility that the design freedom of the polyimide film may be reduced.

A varnish for forming a polyimide film can be obtained by dissolving tetracarboxylic acid dianhydride and diamine as raw materials of polyamic acid in a solvent and then promoting a condensation polymerization reaction of tetracarboxylic acid dianhydride and diamine. . The polyamic acid which is a precursor of polyimide is imidated by heating and becomes polyimide. The polyimide film is formed by applying the varnish to the outer peripheral surface of the intermediate insulating layer 4 or the other insulating film, and then baking to evaporate most of the solvent and imidizing the polyamic acid in the solvent. In addition, additives such as a pigment, a dye, an inorganic or organic filler, a lubricant, and an adhesion improver may be added to the varnish for forming a polyimide film, as needed.

As tetracarboxylic acid dianhydride which becomes a raw material of polyamic acid, at least one of pyromellitic acid dianhydride (PMDA) and 3,3 ', 4,4'-biphenyl tetracarboxylic acid dianhydride (BPDA) is used. Used. Therefore, the polyimide in the polyimide film contains at least one of a structural unit derived from pyromellitic dianhydride and a structural unit derived from 3,3 ′, 4,4′-biphenyltetracarboxylic acid dianhydride. There is.

Moreover, it is not limited to these acid anhydrides, For example, 4,4'- oxydiphthalic acid dianhydride (ODPA), 3,3 ', 4,4' as tetracarboxylic dianhydride used as the raw material of a polyamic acid -Benzophenone tetracarboxylic acid dianhydride (BTDA), 3,3 ', 4,4'-diphenyl sulfone tetracarboxylic acid dianhydride, bicyclo [2.2.2] oct-7-ene-2,3,5 1,6-tetracarboxylic acid dianhydride, 1,2,4,5-cyclohexanetetracarboxylic acid dianhydride, 2,2-bis (3,4-dicarboxylicoxyphenyl) hexafluoropropane dianhydride, 5- (5 Acid anhydrides such as 2,5-dioxotetrahydrofuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid dianhydride may be used.

At least one of 4,4'-diaminodiphenyl ether (ODA) and 4,4'-bis (4-aminophenoxy) biphenyl (BAPB) is used as a diamine which is a raw material of polyamic acid. Therefore, the polyimide in the polyimide film contains at least one of structural units derived from 4,4'-diaminodiphenyl ether and structural units derived from 4,4'-bis (4-aminophenoxy) biphenyl.

Moreover, it is not limited to these diamines, For example, 4,4'- methylenedianiline (MDA), 2, 2-bis [4- (amino phenoxy) phenyl] propane (BAPP) as a diamine used as the raw material of a polyamic acid 1,4-bis (4-aminophenoxy) benzene (TPE-Q), 1,3-bis (4-aminophenoxy) benzene (TPE-R), 1,1-bis [4- (4-aminophenoxy) ) Diamines such as phenyl] cyclohexane (4-APBZ), 1,3-bis (3-aminophenoxy) benzene (3-APB), 1,5-bis (3-aminophenoxy) naphthalene (1,5-BAPN) May be used.

Examples of the solvent contained in the varnish for forming a polyimide film include N-methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP), N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), Two types of aprotic polar solvents such as monomethylformaldehyde (NMF), β-alkoxypropionamide, 3-methoxy-N, N-dimethylpropanamide, dimethylsulfoxide (DMSO), and γ-butyrolactone (γ-BL) The above is used in combination.

The solvent which has not volatilized by baking remains on the polyimide film. That is, the polyimide film contains at least two or more kinds of residual solvents having different boiling points.

As a minimum of content of each residual solvent to polyimide membrane, 0.001 mass% is preferred, 0.003 mass% is more preferred, and 0.005 mass% is more preferred. On the other hand, the upper limit of the content is preferably less than 0.1% by mass, more preferably less than 0.08% by mass, and still more preferably less than 0.07% by mass. If the content is less than the above lower limit, the surface of the polyimide film may not be formed smooth. On the other hand, when the content is equal to or more than the upper limit, the dielectric constant of the polyimide film may be increased, and the insulation of the polyimide film may be reduced. The content of each of the residual solvents in the insulating layer is the same as the residual solvent in the polyimide film.

The lower limit of the total content of the two or more types of residual solvents relative to the polyimide film is preferably 0.002% by mass, more preferably 0.01% by mass, and still more preferably 0.02% by mass. On the other hand, the upper limit of the content is preferably 0.1% by mass, more preferably 0.09% by mass, and still more preferably 0.08% by mass. When the content is less than the above lower limit, the surface of the polyimide film may not be formed smooth, and the affinity between the polyimide film and the varnish for forming the insulating film may not be sufficiently improved. On the other hand, when the content exceeds the upper limit, the dielectric constant of the polyimide film may be increased, and the insulation of the polyimide film may be reduced. The total content of the two or more types of residual solvents in the insulating layer is the same as the total content of the two or more types of residual solvents in the polyimide film.

(advantage)
In the insulated wire 1, the insulating film 3a, the insulating film 3b and the insulating film 3c forming the laminated structure are a polyimide film, and the polyimide film is mainly composed of polyimide and contains two or more kinds of residual solvents having different boiling points. doing. For this reason, the said insulated wire 1 suppresses rapid drying of the varnish for polyimide film formation at the time of forming a polyimide film, and promotes smoothing of the surface of a polyimide film. Moreover, since the said insulated wire 1 contains 2 or more types of residual solvents of a suitable quantity in a polyimide film, the affinity of the polyimide film and the varnish for other insulating film formation is improved. Therefore, the said insulated wire 1 can improve the adhesiveness between the insulation films which form the insulating layer 3.

In the insulated wire 1, the polyimide in the polyimide film is a structural unit derived from pyromellitic dianhydride and a structural unit derived from 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride. Since the insulating layer 3 contains at least one of structural units derived from 4,4'-diaminodiphenyl ether and / or structural units derived from 4,4'-bis (4-aminophenoxy) biphenyl, The heat resistance of the formed polyimide film can be improved.

[Other embodiments]
It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present disclosure is not limited to the configurations of the above embodiments, but is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Although the said embodiment demonstrated the thing in which the insulated wire 1 was equipped with the intermediate | middle insulation layer 4 between the metal conductor 2 and the insulating layers 3, the insulated wire 1 does not need to be equipped with the intermediate | middle insulation layer 4. FIG. That is, the insulated wire 1 may be provided with the linear metal conductor 2 and the insulating layer 3 directly laminated on the outer peripheral surface of the metal conductor 2.

In the above embodiment, although the polyimide film has been described as containing two or more types of residual solvents having different boiling points, the polyimide film may contain three or more types of residual solvents having different boiling points. In this case, the content of each of the two or more types of residual solvents selected from the three or more types of residual solvents contained in the polyimide film is 0.001% by mass or more and less than 0.1% by mass, and the polyimide film is The total content of all residual solvents contained may be 0.002% by mass or more and 0.1% by mass or less.

Hereinafter, the present invention will be more specifically described by way of examples, but the present invention is not limited to the following examples.

[No. 1 to No. Preparation of varnish for forming a polyimide film of 15]
The varnish for polyimide film formation was prepared using the following tetracarboxylic acid dianhydride, diamine and a solvent. A varnish for forming a polyimide film is to promote the condensation polymerization reaction of tetracarboxylic acid dianhydride and diamine after dissolving tetracarboxylic acid dianhydride and diamine as raw materials of polyamic acid in a solvent in an equimolar ratio. Obtained by The composition of the tetracarboxylic acid dianhydride as the raw material, the composition of the diamine and the composition of the solvent used are shown in Table 1. In Table 1, the composition ratio of tetracarboxylic dianhydride and the composition ratio of diamine are shown by molar ratio, and the composition ratio of the solvent is shown by mass ratio.

(Tetracarboxylic acid dianhydride)
As a tetracarboxylic acid dianhydride used as a raw material of a polyamic acid, pyromellitic dianhydride and 3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride were used. In Table 1, these acid anhydrides are denoted as PMDA and BPDA, respectively, and the composition ratios are shown such that the total of these is 100.

(Diamine)
4,4'-Diaminodiphenyl ether and 4,4'-bis (4-aminophenoxy) biphenyl were used as diamines to be a raw material of the polyamic acid. In addition, in Table 1, these diamine is each displayed as ODA and BAPB, and the composition ratio is shown so that the sum total of these may be set to 100.

(solvent)
As the solvent, “NMP” (N-methyl pyrrolidone, boiling point 202 ° C.) of Mitsubishi Chemical Corporation, “NMF” (monomethyl formaldehyde, boiling point 199 ° C.) of Mitsubishi Gas Chemical Co., Ltd., “DMAC” of Mitsubishi Gas Chemical Co., Ltd. (N, N-dimethylacetamide, boiling point 165 ° C.), Tokyo Chemical Industry Co., Ltd. “D0722” (N, N-dimethylformamide, boiling point 153 ° C.), Idemitsu Kosan Co., Ltd. “Equamide M100” (β-alkoxypropionamide) Boiling point 216 ° C.), “E0358” (N-ethyl pyrrolidone, boiling point 218 ° C.) of Tokyo Chemical Industry Co., Ltd., and “GBL” (γ-butyrolactone, boiling point 204 ° C.) of Mitsubishi Chemical Co., Ltd. were used. In Table 1, these are indicated as NMP, NMF, DMAc, DMF, M100, NEP and γ-BL, respectively, and the composition ratios are shown such that the total of these is 100.

[No. 1 to No. Test of 15 Insulated Wires]
No. 1 to No. After applying a varnish for forming a polyimide film on the outer surface of a copper wire of 1.0 mm in diameter, most of the solvent is evaporated by baking and the polyamic acid in the solvent is imidized to form a polyimide film having an average thickness of 3 μm. It formed. Then, the application and baking of the varnish for forming a polyimide film were repeated 20 times to form an insulating layer having an average thickness of 60 μm. 1 to No. Fifteen insulated wires were produced. With respect to this insulated wire, the content of each of the residual solvents for the polyimide film and the relative dielectric constant of the insulating layer were measured. Moreover, the peeling test was done about this insulated wire. The measurement results and the test results are shown in Table 2.

(Measurement of residual solvent content)
The content of the residual solvent with respect to the polyimide film was measured by gas chromatography.

(Measurement of dielectric constant)
The measurement of the relative permittivity of the insulating layer is performed by applying silver paste to three places on the surface of the insulated wire, and then measuring the capacitance between the silver paste and the copper wire with an LCR meter at normal temperature. The relative dielectric constant was calculated from the value of the capacitance and the thickness of the insulating layer.

(Peeling test)
In the peeling test, after prestretching the insulated wire by 20% in the longitudinal direction, the insulated wire is wound 30 times around an iron core having the same diameter as the insulated wire, and whether cracking or peeling occurs in the insulating layer Adopted a method to confirm the In Table 2, A indicates that cracking or peeling did not occur in the insulating layer, and B indicates that cracking or peeling occurred in the insulating layer.

No. 1 to No. As shown in Table 2, the 12 insulated wires are examples in which the polyimide film forming the insulating layer contains two or three types of residual solvents, and the content of each residual solvent to the polyimide film is 0.001 mass. % Or more and less than 0.1% by mass, and the total content of the residual solvent to the polyimide film is 0.002% by mass or more and 0.1% by mass or less. No. 1 to No. In the 12 insulated wires, it was confirmed that the relative dielectric constant of the insulating layer is 3.2 or more and 3.3 or less and that cracking or peeling does not occur in the insulating layer even in the peeling test. That is, no. 1 to No. In the 12 insulated wires, the dielectric constant of the insulating layer is low, and it can be said that the adhesion between the polyimide films forming the insulating layer is high.

No. 13 to No. The insulated wire of 14 is an example in which the polyimide film forming the insulating layer contains only one type of residual solvent. No. 13 to No. In the insulated wire of No. 14, it was confirmed that cracking and peeling occur in the insulating layer also in the peeling test. That is, no. 13 to No. In the 14 insulated wires, it can be said that the adhesion between the polyimide films forming the insulating layer is not sufficient.

No. The insulated wire of No. 15 is an example in which the polyimide film forming the insulating layer contains only one type of residual solvent, and is an example in which the content of the residual solvent with respect to the polyimide film is 0.1% by mass or more. No. In the 15 insulated wires, the dielectric constant of the insulating layer is 3.6, and it can be said that the dielectric constant of the insulating layer is high.

1 Insulated Wire 2 Metal Conductor 3 Insulating Layer 3a, 3b, 3c Insulating Coating 4 Intermediate Insulating Layer

Claims (8)

An insulated wire comprising: a linear metal conductor; and an insulating layer laminated on the outer peripheral surface side of the metal conductor,
The insulating layer has a laminated structure of two or more insulating films,
At least one of the two or more insulating films is a polyimide film containing polyimide as a main component,
An insulated wire wherein the insulating layer contains two or more kinds of residual solvents having different boiling points. Each content of the said residual solvent with respect to the said insulating layer is 0.001 mass% or more and less than 0.1 mass%,
The insulated wire according to claim 1, wherein a total content of the two or more types of residual solvents with respect to the insulating layer is 0.002% by mass or more and 0.1% by mass or less. The polyimide in the polyimide film contains at least one of a structural unit derived from pyromellitic dianhydride and a structural unit derived from 3,3 ′, 4,4′-biphenyltetracarboxylic acid dianhydride An insulated wire according to claim 1 or claim 2. The polyimide according to claim 1, wherein the polyimide in the polyimide film contains at least one of a structural unit derived from 4,4'-diaminodiphenyl ether and a structural unit derived from 4,4'-bis (4-aminophenoxy) biphenyl. The insulated wire according to claim 2 or claim 3. It comprises an intermediate insulating layer laminated between the metal conductor and the insulating layer,
The insulated wire according to any one of claims 1 to 4, wherein the intermediate insulating layer is formed of a resin composition containing a thermosetting resin, a thermoplastic resin, or a mixture thereof as a main component. The insulated wire according to claim 5, wherein the resin composition contains polyamide imide as a main component. The insulated wire according to claim 5 or 6, wherein the average thickness of the intermediate insulating layer is 5 μm or more and 250 μm or less. An insulated wire comprising: a linear metal conductor; and an insulating layer laminated on the outer peripheral surface side of the metal conductor,
The insulating layer has a laminated structure of two or more insulating films,
At least one of the two or more insulating films is a polyimide film containing polyimide as a main component,
The insulating layer contains two or more residual solvents having different boiling points,
Each content of the said residual solvent with respect to the said insulating layer is 0.001 mass% or more and less than 0.1 mass%,
The total content of the two or more types of residual solvents in the insulating layer is 0.002% by mass or more and 0.1% by mass or less,
The polyimide in the polyimide film contains at least one of a structural unit derived from pyromellitic dianhydride and a structural unit derived from 3,3 ′, 4,4′-biphenyltetracarboxylic acid dianhydride Yes,
An insulated wire comprising at least one of a structural unit derived from 4,4'-diaminodiphenyl ether and a structural unit derived from 4,4'-bis (4-aminophenoxy) biphenyl in the polyimide film.

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