JP5941866B2 - Insulated wire - Google Patents

Description

  The present invention relates to an insulated wire used for forming a coil or the like of a motor.

  In recent years, electronic devices and electrical devices have been miniaturized, and as a result, coils installed in these devices are also enamels with rectangular cross-sections from those using conventional circular enamel wires (round enamel wires). The one using the wire (flat angle enamel wire) is becoming mainstream. This flat enameled wire is a conductor with a rectangular cross section (flat rectangular conductor) coated with an insulating paint and baked to provide an insulating film. By using a flat enameled wire, the gap between the enameled wires when wound around a coil (That is, the space factor of the enameled wire can be increased), and the coil can be reduced in size. In recent years, so-called edgewise winding coils in which a short side of a flat enameled wire is wound vertically with an inner diameter surface are being used frequently because of excellent heat dissipation and frequency characteristics. In such an edgewise winding coil, since the load applied to the flat enameled wire is very large, the flat enameled wire is required to have high flexibility.

  By the way, the insulating film of the enamel wire used for such a motor coil is generally required to have heat resistance, heat deterioration property, conductor adhesion, etc. in addition to flexibility. Therefore, conventionally, resins having excellent heat resistance such as polyamideimide and polyimide, and those having an adhesion improver added to these resins to improve the adhesion to the conductor (high adhesion polyamideimide, high adhesion polyimide) Etc.), those in which a flexible structure is introduced into the molecule to improve flexibility (highly flexible polyamideimide, etc.), etc., are used singly or in combination (for example, see Patent Documents 1 to 3). .) As an example of a combination, a high adhesion polyamide-imide resin to which an adhesion improver is added is coated in close contact with the conductor, and the outer periphery thereof is coated with an aromatic polyimide having excellent heat resistance.

  In recent years, partial discharge characteristics have also been regarded as important. That is, if partial discharge occurs on the surface and inside of the insulating film, electrical deterioration may occur, leading to dielectric breakdown. With the recent progress in energy saving and increased use of high-voltage inverters, it is necessary to improve the partial discharge characteristics of enameled wires.

  As a method for improving the partial discharge characteristics, it is conceivable to increase the thickness of the insulating film or to add an inorganic filler. However, flexibility is reduced when an inorganic filler is added. On the other hand, when the insulating film is thickened, the number of times the insulating paint is applied and baked increases, so that the conductor is oxidized during that time, and the adhesion between the insulating film and the conductor may be reduced.

  For this reason, the technology that can improve the partial discharge characteristics without reducing the conductor adhesion and flexibility, that is, the heat resistance, the heat deterioration property, the conductor adhesion, the flexibility, and the partial discharge. There is a demand for a technique capable of forming an insulating film having excellent characteristics.

JP 2005-304223 A Japanese Patent Application Laid-Open No. 2011-9015 JP 2011-68875 A

  The present invention has been made in response to such a conventional situation, and has an insulating film that has excellent heat resistance, heat deterioration property, conductor adhesion, flexibility, and excellent partial discharge characteristics. The purpose is to provide electric wires.

  The insulated wire according to the first aspect of the present invention is a dimer acid diisocyanate provided on a conductor, a first layer made of a first polyimide not containing an adhesion improver, and the first layer. From the 2nd layer which consists of polyamideimide obtained by making the isocyanate component and acid component which contain 10-70 mol% react, and the 3rd layer which consists of the 2nd polyimide provided on this 2nd layer The ratio of the thickness of the first to third layers to the total thickness of the insulating film is 10 to 25% for the first layer, 10 to 75% for the second layer, The third layer is 10 to 75%.

  According to a second aspect of the present invention, in the insulated wire according to the first aspect, the ratio of the thickness of the first to third layers to the thickness of the entire insulating film is 10 to 25% for the first layer. The second layer is 50 to 75%, and the third layer is 10 to 30%.

  According to a third aspect of the present invention, in the insulated wire according to the first aspect or the second aspect, the adhesion strength between the conductor and the first layer is 40 g / mm or more. is there.

  According to a fourth aspect of the present invention, in the insulated wire according to any one of the first to third aspects, the partial discharge start voltage is 1000 V or more.

  According to a fifth aspect of the present invention, in the insulated wire according to any one of the first to fourth aspects, the polyamideimide has a glass transition point (Tg) of 210 to 270 ° C. It is what.

  According to a sixth aspect of the present invention, in the insulated wire according to any one of the first to fifth aspects, the acid component includes trimellitic anhydride.

  According to a seventh aspect of the present invention, in the insulated wire according to any one of the first to sixth aspects, the thickness of the entire insulating film is 60 to 200 μm.

  According to an eighth aspect of the present invention, in the insulated wire according to any one of the first to seventh aspects, the conductor is a flat conductor.

  According to a ninth aspect of the present invention, in the insulated wire according to the eighth aspect, the rectangular conductor has a rectangular cross section having a width of 2.0 to 7.0 mm and a thickness of 0.7 to 3.0 mm. It is a feature.

  ADVANTAGE OF THE INVENTION According to this invention, the insulated wire which can comprise the insulating film which is excellent in heat resistance, heat deterioration property, conductor adhesiveness, and flexibility, and is excellent also in partial discharge characteristics is provided.

It is sectional drawing which shows one Embodiment of the insulated wire of this invention.

  Hereinafter, embodiments of the present invention will be described. Although the description will be made based on the drawings, the drawings are provided for illustration only, and the present invention is not limited to the drawings.

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

  As shown in FIG. 1, this flat enameled wire includes a rectangular conductor 10 having a rectangular cross section formed by wire drawing, and an insulating film 20 having a three-layer structure formed in order on the rectangular conductor 10, that is, A film composed of one layer 21, second layer 22, and third layer 23 is provided.

  The flat conductor 10 has, for example, a metal wire such as a copper wire or a copper alloy wire having a rectangular cross section with a width (W) of 2.0 to 7.0 mm and a thickness (H) of 0.7 to 3.0 mm. Consists of The four corners of the rectangular cross section may or may not be rounded, but are not rounded from the viewpoint of increasing the space factor when wound around the coil (that is, Even if the cross section is rectangular) or a rounded shape is used, the radius of the rounded shape is preferably 0.3 mm or less. Examples of the material of the flat conductor 10 include copper, copper alloys, aluminum, iron, silver, and alloys thereof, but copper or copper alloys are preferable from the viewpoint of mechanical strength, conductivity, and the like.

  The first layer 21 is a layer made of polyimide that does not contain an adhesion improver (also referred to as an adhesion improver-free polyimide or a first polyimide), and a polyimide resin varnish that does not contain an adhesion improver ( It is formed by applying and baking an adhesion improver-free polyimide resin varnish) on the flat conductor 10. The polyimide resin varnish containing no adhesion improver may be any polyimide resin varnish as long as it does not contain an adhesion improver.

  Generally, there are polyimide resin varnishes in which a polyimide resin soluble in a solvent is dissolved in a solvent, and a polyimide resin precursor such as polyamic acid dissolved in a solvent, which becomes a polyimide resin by high-temperature heat treatment. Yes, both can be used. From the viewpoint of heat resistance, it was selected from pyromellitic dianhydride (PMDA), benzophenone tetracarboxylic dianhydride (BTDA), 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, and the like. One or more tetracarboxylic dianhydrides and 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 1,3-bis (4-aminophenoxy) An aromatic diamine such as benzene, 1,3-bis (3-aminophenoxy) benzene, 3,3′-diaminodiphenylsulfone, or an aromatic diisocyanate is mixed with N-methyl-2-pyrrolidone, N, N′-dimethyl. A wholly aromatic polyimide resin varnish obtained by reacting in an organic solvent such as acetamide (DMAc) is preferred. That's right.

  Other examples of tetracarboxylic dianhydrides include 3,3 ′, 4,4′-diphenyl sulfoxide tetracarboxylic dianhydride, 2,3,3 ′, 4′-diphenyl ether tetracarboxylic dianhydride, 3,4,3 ′, 4′-diphenylsulfide tetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4′-diphenylmethanetetracarboxylic Acid dianhydride, 3,4,3 ′, 4′-diphenyl (2,2-isopropylidene) tetracarboxylic dianhydride, 2,3,3 ′, 4′-diphenylsulfoxide tetracarboxylic dianhydride, 3,4,3 ′, 4′-diphenyl ether tetracarboxylic dianhydride, 3,4,3 ′, 4′-diphenylsulfone tetracarboxylic dianhydride, 2,3,3 ′, 4′-diphenyl Sulfontracarboxylic dianhydride, 2,3,3 ′, 4′-diphenylsulfide tetracarboxylic dianhydride, 3,4,3 ′, 4′-diphenylsulfanetetracarboxylic dianhydride, 2,3 , 3 ′, 4′-benzophenonetetracarboxylic dianhydride, 2,3,3 ′, 4′-diphenyl (2,2-isopropylidene) tetracarboxylic dianhydride, 4,4 ′-(hexafluoroisopropyl ) Phthalic dianhydride, bisphenolic dianhydride and the like.

  Other examples of aromatic diamines include 4,4′-diaminodiphenyl sulfone, 1,4-diaminobenzene, 1,3-diaminobenzene, 2,2′-dimethyl-4,4′-diaminobiphenyl, 2, 4-diaminotoluene, 3,4'-biphenyldiamine, 3,4'-diaminodiphenyl sulfoxide, 2,2-bis (3-aminophenyl) propane, 4,4'-diaminobenzophenone, 3,3'-biphenyldiamine 3,4′-diaminodiphenyl ether, 2,6-diaminotoluene, 4,4′-biphenyldiamine, 3,3′-diaminodiphenyl ether, 4,4′-bis (4-aminophenyl) sulfide, 3,3 ′ -Diaminodiphenylmethane, 2,2-bis (4-aminophenyl) propane, 2,2- (3-aminophenyl) (4-aminophenyl) propane, 3,3′-diaminobenzophenone, 3,3′-dimethyl-4,4′-diaminobiphenyl, 3,3′-bis (4-aminophenyl) sulfide, 4,4′- Diaminodiphenyl sulfoxide, 3,4'-diaminobenzophenone, 3,3'-diaminodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfone, 2,5-diaminotoluene, 3,3'-diaminodiphenyl ether, 4,4'- Bis (4-aminophenyl) sulfide, 3,3′-diaminodiphenylmethane, 2,2-bis (4-aminophenyl) propane, 2,2- (3-aminophenyl) (4-aminophenyl) propane, 3, 3'-diaminobenzophenone, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2 -Dimethyl-4,4'-diaminobiphenyl, 3,4'-bis (4-aminophenyl) sulfide, 3,3'-bis (4-aminophenyl) sulfide, 4,4'-diaminodiphenyl sulfoxide, 3, 4'-diaminobenzophenone, 3,3'-diaminodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfone, 2,5-diaminotoluene, 3,3'-hydroxy-4,4'-diaminobiphenyl, diaminobenzoanilide, And methylene dianiline.

  Examples of the organic solvent used in the polymerization of tetracarboxylic dianhydride and aromatic diamine and the like include N-methyl-2-pyrrolidone and N, N′-dimethylacetamide (DMAc) as well as N, N— Dimethylformamide, N, N′-diethylacetamide, 1,3-dimethyl-2-imidazolidinone, N-methylcaprolactam, hexamethylphosphoric triamide, 1,2-dimethoxyethane, diglyme, triglyme, tetrahydrofuran, 1, Examples include 4-dioxane, γ-butyrolactone, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, diethoxyethane, dimethyl sulfoxide, and sulfolane.

  Examples of commercially available wholly aromatic polyimide resin varnishes suitable for the formation of the first layer 21 include, for example, Toray Nice # 3000 manufactured by Toray Industries, Inc., U-Varnish manufactured by Ube Industries, Ltd., and UMC E706 (above, trade name) and the like.

  In addition, the adhesion improver here is a component having an effect of enhancing the adhesion to the conductor 10, for example, thiadiazole, thiazole, mercaptobenzimidazole, thiophenol, thiophene, thiol, tetrazole, benzimidazole, butylated melamine Heterocyclic mercaptan and the like are exemplified.

  By forming the first layer 21 with a polyimide resin varnish that does not contain such an adhesion improver, it is possible to ensure good adhesion to the conductor without depending on the film thickness of the insulating film 20. . In other words, even if the insulating film 20 is thickened to enhance the partial discharge characteristics, the adhesion to the conductor is reduced as in the case of a polyimide resin varnish or polyamideimide resin containing an adhesion improver. There is no. This is because when a polyimide resin varnish that does not contain an adhesion improver is used, it is possible to prevent the conductor from being oxidized during the subsequent heat treatment, whereas a polyimide resin varnish or polyamide containing an adhesion improver. This is probably because the imide resin varnish promotes the oxidation of the conductor. When a polyamideimide resin varnish that does not contain an adhesion improver is used, the required adhesion to the conductor cannot be ensured regardless of the film thickness because the adhesion to the conductor itself is low.

Regardless of the thickness of each of the first to third layers 21 to 23, the first layer 21 preferably has an adhesive strength of 40 g / mm or more, more preferably 60 g / mm or more. . The adhesion between the first layer 21 and the conductor is a value measured by performing a 180 ° peel test between the insulating film and the conductor.

  The second layer 22 is a layer made of a polyamideimide (also referred to as a highly flexible polyamideimide) obtained by reacting an isocyanate component containing 10 to 70 mol% of dimer acid diisocyanate with an acid component. It is formed by applying and baking a resin varnish containing a flexible polyamideimide on the first layer 21.

  By using an isocyanate component containing 10 to 70 mol% of dimer acid diisocyanate, the second layer 22 having excellent wear resistance as well as flexibility is formed, and excellent workability is imparted to the insulated wire. be able to. In addition, it is preferable that dimer acid diisocyanate is 30-60 mol%.

  Other isocyanate components used in combination include 2,4′-diphenylmethane diisocyanate (2,4′-MDI), 4,4′-diphenylmethane diisocyanate (4,4′-MDI), 3,4′-diphenylmethane diisocyanate, 3 , 3'-diphenylmethane diisocyanate, 2,3'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, tolylene diisocyanate (TDI), diphenyl ether diisocyanate, naphthalene diisocyanate, phenylene diisocyanate, xylylene diisocyanate, diphenylsulfone diisocyanate, biphenyl Examples include tolylene diisocyanate, dianisidine diisocyanate, and isomers thereof. In addition, aliphatic diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, methylene dicyclohexyl diisocyanate, xylylene diisocyanate and cyclohexane diisocyanate, polyfunctional isocyanates such as triphenylmethane triisocyanate, multimers such as polymeric isocyanate or tolylene diisocyanate, etc. Can be used together.

  The acid component includes trimellitic anhydride (TMA), pyromellitic dianhydride (PMDA), benzophenonetetracarboxylic dianhydride (BTDA), biphenyltetracarboxylic dianhydride, diphenylsulfonetetracarboxylic acid. Aromatic tetracarboxylic dianhydrides such as dianhydrides (DSDA) and oxydiphthalic dianhydrides, and isomers thereof, butanetetracarboxylic dianhydrides, 5- (2,5-dioxotetrahydro-3-furanyl ) -3-cyclohexene-1,2-dicarboxylic anhydride and other alicyclic tetracarboxylic dianhydrides, and tricarboxylic acids such as trimesic acid and tris (2-carboxyethyl) isocyanurate (CIC acid) Examples include acids and isomers thereof. Among these, trimellitic anhydride (TMA) that is inexpensive and excellent in safety is preferable.

  In addition to the isocyanate component and the acid component, a polycarboxylic acid may be added. Examples of the polycarboxylic acid include aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, aromatic tricarboxylic acids such as trimellitic acid and hemmellitic acid, and aliphatic polycarboxylic acids such as dimer acid.

  Furthermore, as a solvent for reacting the isocyanate component and the acid component, aprotic polar solvents such as 2-pyrrolidone, N-methyl-2-pyrrolidone (NMP), N, N-dimethylacetamide, phenol, cresol, Examples thereof include phenol solvents such as xylenol.

  When reacting the isocyanate component and the acid component, reaction catalysts such as amines, imidazoles, imidazolines may be used. The reaction catalyst is preferably one that does not inhibit the stability of the resin varnish.

  The highly flexible polyamideimide constituting the second layer 22 preferably has a glass transition point (Tg) of 210 to 270 ° C, more preferably 230 to 260 ° C.

  The third layer 23 is a layer made of polyimide (also referred to as second polyimide), and is formed by applying and baking a polyimide resin varnish on the second layer 22. The polyimide resin varnish that forms the third layer 23 is not particularly limited, and various conventionally known polyimide resin varnishes can be used. Further, the same type as that used in the first layer 21 may be used, or may be different. From the viewpoint of improving heat resistance and thermal deterioration, those mentioned as examples suitable for forming the first layer 21, that is, pyromellitic dianhydride (PMDA), benzophenone tetracarboxylic dianhydride (BTDA) One or more tetracarboxylic dianhydrides selected from 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and the like, and 4,4′-diaminodiphenyl ether, 4,4 ′ -Aromatics such as diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 3,3'-diaminodiphenylsulfone Diamine or aromatic diisocyanate and organic compounds such as N-methyl-2-pyrrolidone and N, N′-dimethylacetamide (DMAc) A wholly aromatic polyimide resin varnish obtained by reacting in a solvent is preferred.

  As described above, the first layer 21, the second layer 22, and the third layer 23 are each composed of an adhesion improver-free polyimide resin varnish, a highly flexible polyamideimide resin varnish, and a polyimide resin varnish. It is formed by applying and baking on the flat conductor 10 in order. The method of applying and baking each resin varnish is not particularly limited. For example, a conventionally known method, for example, the flat conductor 10 or the first layer 21 or the second layer 22 is placed in a tank containing the resin varnish. A method of baking in a baking furnace after passing the formed flat conductor 10 can be used.

  In the present invention, each layer thickness (t1, t2, and t3) of the first layer 21, the second layer 22, and the third layer 23 is the sum of them, that is, the thickness (T) of the insulating film 20. The ratio of each layer is set so that the first layer 21 is 10 to 25%, the second layer 22 is 10 to 70%, and the third layer 23 is 10 to 70%. If the thickness of the 1st layer 21 is less than the said range, the adhesiveness with respect to the flat conductor 10 will fall, and if it exceeds the said range, flexibility will fall. When the thickness of the second layer 22 is less than the above range, the flexibility is lowered, and when it exceeds the above range, the heat resistance and the heat deterioration property are lowered. When the thickness of the third layer 23 is less than the above range, the heat resistance and thermal degradation are reduced, and when it exceeds the above range, the wear resistance is reduced. The ratio of each layer to the thickness (T) of the insulating film 20 is that the first layer 21 is 10 to 25%, the second layer 22 is 50 to 75%, and the third layer 23 is 10 to 30%. preferable.

The thickness (T) of the insulating film 20 is preferably 60 to 200 μm, and more preferably 60 to 160 μm. When the thickness (T) of the insulating film 20 is less than 60 μm, the withstand voltage characteristics are insufficient. From the viewpoint of partial discharge characteristics, the thickness (T) of the insulating film 20 is:
It is preferable to set it as 80-120 micrometers. By setting it as such thickness, partial discharge start voltage 1000V or more can be achieved.

  In the flat enameled wire of the present embodiment, the first layer 21 made of polyimide containing no adhesion improver on the flat conductor 10 and 10 dimer acid diisocyanate provided on the first layer 21 are used. A polyamideimide obtained by reacting an isocyanate component containing ˜70 mol% and an acid component, that is, a second layer 22 comprising a highly flexible polyamideimide, and a polyimide comprising a polyimide provided on the second layer 22. 3 is provided with the insulating film 20 composed of the three layers 23, so that even if the insulating film 20 is thickened to enhance the partial discharge characteristics, the adhesion of the insulating film 20 to the flat conductor 10 does not decrease. The film 20 can have good conductor adhesion. The insulating film 20 also has good flexibility, heat resistance, and heat deterioration. Therefore, the flat enameled wire can be provided with the insulating film 20 that has good heat resistance, thermal deterioration, conductor adhesion, flexibility, and excellent partial discharge characteristics.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage. . For example, the above embodiment is an example in which the present invention is applied to a flat enameled wire, but it goes without saying that the present invention can also be applied to a round enameled wire using a normal circular conductor. Since the insulated wire of the present invention has excellent flexibility, it can be sufficiently applied as a winding of an edgewise winding coil and can have excellent partial discharge characteristics. It can be applied to required applications.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. In the following description, “part” means “part by mass” unless otherwise specified.

[Preparation of highly flexible polyamideimide resin varnish]
In a flask equipped with a stirrer, nitrogen inlet pipe and heating / cooling device, a mixture of 2,4′-MDI and 4,4′-MDI as an isocyanate component, dimer acid diisocyanate (DDI), and trimellitic anhydride as an acid component And N-methyl-2-pyrrolidone as a solvent was added, and the temperature was raised from room temperature to 140 ° C. over 2 hours with stirring in a nitrogen atmosphere. After reacting at this temperature for 3 hours, N, N— Dilution with dimethylformamide (DMF) and cooling to room temperature gave a highly flexible polyamideimide resin varnish having a nonvolatile content of 30.0% by mass. The nonvolatile content is a value measured according to JIS C 2351.

[Manufacture of insulated wires]
Example 1
On a flat copper conductor, a polyimide resin varnish that does not contain an adhesion improver (trade name Torenice # 3000; written as PI-1) manufactured by Toray Industries, Inc. is applied and baked to form an 11 μm thick film (first layer). Then, the highly flexible polyamide-imide resin varnish (denoted as highly flexible PAI) is applied onto this first layer and baked to form a 77 μm-thick film (second layer). On the two layers, the same polyimide resin varnish (PI-1) as that of the first layer is applied and baked to form a 22 μm-thick film (third layer). An insulated wire having a thickness of 1.6 mm and a width of 2.4 mm is formed. Obtained.

(Examples 2 to 10)
Insulated wires having the configurations and dimensions shown in Table 1 in the same manner as in Example 1 except that the conductor, the film thickness of the first layer to the third layer, and / or the material for forming the first layer or the third layer were changed. Got. In addition, the material used for formation of the first layer and the third layer in Example 5 and Example 7, respectively, is a U-varnish A of polyimide resin varnish that does not contain an adhesion improver (trade name, manufactured by Ube Industries, Ltd.); PI-2). In addition, the materials used for forming the first layer and the third layer in Example 6 and Example 8, respectively, are E706 of polyimide resin varnish that does not contain an adhesion improver (trade name; manufactured by UMC); ).

(Comparative Examples 1-6)
With the configuration and dimensions described in Table 2, an insulated wire was obtained. The high adhesion polyimide resin varnish (expressed as high adhesion PAI) used in Comparative Examples 1 and 4 and the high adhesion polyimide resin varnish (expressed as high adhesion PI) used in Comparative Example 5 are as follows.
High adhesion PAI: HI406-30 (trade name, manufactured by Hitachi Chemical Co., Ltd.) containing an adhesion improver, mercaptobenzimidazole Containing the agent mercaptobenzimidazole

About each obtained insulated wire, various characteristics were measured and evaluated by the method shown below.
[Heat-resistant]
The glass transition point (Tg) of the material constituting the second layer was measured using a thermomechanical analyzer.
[Softening temperature]
JIS C 3216-6 JA. Measured according to 4.
[Heat degradation]
The insulated wire sample was heated and deteriorated at 250 ° C. for 48 hours, and then subjected to a flatwise bending test and evaluated according to the following criteria.
◎: Insulation film does not crack or crack when bending diameter is less than 9mmφ ○: Insulation film does not crack or crack when bending diameter is 9mmφ or more but less than 18mmφ △: Insulation with bending diameter less than 18mmφ or less than 27mmφ No cracking or cracking of the film ×: Insulation film cracking or cracking occurred at a bending diameter of 27 mmφ or more [wet heat]
The insulated wire sample was allowed to stand for 120 hours at 150 ° C. and 0.2% by volume of water, then subjected to a flatwise bending test and evaluated according to the following criteria.
◎: Insulation film does not crack or crack when bending diameter is less than 5mmφ ○: Insulation film does not crack or crack when bending diameter is 5mmφ or more but less than 10mmφ △: Insulation with bending diameter of 10mmφ or more but less than 20mmφ No cracking or cracking of film ×: Insulation film cracking or cracking occurred at a bending diameter of 20 mmφ or more [Partial discharge start voltage (PDIV)]
When a voltage was applied at 60 Hz and a boosting rate of 10 V / second using an insulated wire arrow pair sample, the voltage at which discharge of 100 pC occurred was measured. The measurement was performed three times for each sample, and the minimum value was indicated.
[Flexibility]
An insulated wire sample having a length of 25 cm was stretched by 30%, an edgewise bending test was performed, and the following criteria were evaluated (n = 40).
◎: No crack occurrence ○: Crack occurrence rate less than 5% △: Crack occurrence rate 5% or more and less than 10% ×: Crack occurrence rate 10% or more [Adhesion]
A 180 ° peel test between the insulating film and the conductor was performed, and the adhesion (g / mm) of the insulating film was measured.

  These measurement results are shown in Table 1 and Table 2 together with the configuration and dimensions of each insulated wire.

  As is clear from Tables 1 and 2, the insulated wires of the examples are excellent in heat resistance, heat deterioration, wet heat, adhesion, flexibility, and partial discharge characteristics.

  DESCRIPTION OF SYMBOLS 10 ... Flat conductor, 20 ... Insulating film, 21 ... 1st layer, 22 ... 2nd layer, 23 ... 3rd layer.

Claims (9)

A first layer made of a first polyimide containing no adhesion improver on the conductor, an isocyanate component containing 10 to 70 mol% of dimer acid diisocyanate provided on the first layer, and an acid component An insulating film comprising a second layer made of polyamideimide obtained by reaction and a third layer made of second polyimide provided on the second layer,
The ratio of the thickness of the first to third layers to the thickness of the entire insulating film is 10 to 25% for the first layer, 10 to 75% for the second layer, and 10 for the third layer. Insulated electric wire characterized by being -75%.   The ratio of the thickness of the first to third layers to the thickness of the entire insulating film is 10 to 25% for the first layer, 50 to 75% for the second layer, and 10 for the third layer. The insulated wire according to claim 1, which is ˜30%.   The insulated wire according to claim 1 or 2, wherein adhesion strength between the conductor and the first layer is 40 g / mm or more.   The insulated wire according to any one of claims 1 to 3, wherein a partial discharge start voltage is 1000 V or more.   The insulated wire according to any one of claims 1 to 4, wherein the polyamide-imide has a glass transition point (Tg) of 210 to 270 ° C.   The insulated wire according to any one of claims 1 to 5, wherein the acid component includes trimellitic anhydride.   The insulated wire according to any one of claims 1 to 6, wherein the entire insulating film has a thickness of 60 to 200 µm.   The insulated wire according to any one of claims 1 to 7, wherein the conductor is a flat conductor.   9. The insulated wire according to claim 8, wherein the flat conductor has a rectangular cross section having a width of 2.0 to 7.0 mm and a thickness of 0.7 to 3.0 mm.

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