JP6097351B2 - 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.

  A flat enameled wire is obtained by applying an insulating coating on a conductor having a rectangular cross section (flat conductor) and baking it. By using the flat enameled wire, the gap between the enameled wires when wound around the coil is reduced, that is, the space factor of the enameled wire is increased, and the coil can be reduced in size.

  Recently, a so-called edgewise coil, in which a short side of a flat enameled wire is wound vertically with an inner diameter surface, is being frequently used because of its excellent heat dissipation and frequency characteristics. Such a flat enameled wire is required to have high flexibility because the load during processing is very large. In general, in addition to flexibility, heat resistance, thermal degradation, conductor adhesion, and the like are required. For this reason, a polyamideimide layer having excellent flexibility and a polyimide layer having excellent heat resistance are laminated as necessary to form an insulating film.

  For example, in recent years, partial discharge characteristics of insulating films have been regarded as important. If partial discharge occurs on or inside the insulating film, electrical degradation 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. As a method of improving the partial discharge characteristics, a method of providing a pair of polyimide layers so as to sandwich a polyamideimide layer is known (see, for example, Patent Document 1).

JP 2014-203585 A

  2. Description of the Related Art Conventionally, an enameled wire having an insulating film provided with a pair of polyimide layers so as to sandwich a polyamideimide layer is known. However, for conventional enameled wires, the adhesion between the polyimide layer and other parts, specifically, the adhesion between the conductor and the polyimide layer, and between the polyimide layer and the polyamideimide layer is not always sufficient. Not expensive.

  As a method for improving the adhesion between the polyimide layer and the other part, for example, a method of incorporating an adhesion improver into the polyimide layer is conceivable. However, when an adhesion improver is contained in the polyimide layer, the adhesion between the polyimide layer and other parts may be reduced due to deterioration during use.

  In recent years, motors have been used for the power of automobiles. For enameled wires used in such motors, harsh environments such as high-temperature and high-humidity environments, high-vibration environments, insulating oils, machine oils, engine oils, transmission oils, and / or other environments that come into contact with water. Used below. In such a case, if the adhesion between the polyimide layer and other portions is not sufficiently high, the polyamideimide layer or the like may be deteriorated and the mechanical properties and the like may be reduced.

  The present invention has been made in response to such a conventional situation, and has an insulating film provided with a pair of polyimide layers so as to sandwich a polyamideimide layer, and includes a polyimide layer and other portions. It aims at providing the insulated wire excellent in the adhesiveness between.

  The insulated wire according to the embodiment has, on the conductor, a first layer made of polyimide that does not contain an adhesion improver, a second layer made of polyamideimide, and a third layer made of polyimide in this order. The polyimides constituting the first layer and the second layer are made of the first polyimide or the second polyimide shown below independently of each other.

  The first polyimide contains 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride 50 to 90 mol%, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride 5 to 20 mol. % And pyromellitic anhydride in an amount of 5 to 40 mol% is obtained by reacting a diamine component containing 4,4′-diaminodiphenyl ether.

  The second polyimide comprises an acid component composed of 50 to 80 mol% 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 20 to 50 mol% pyromellitic anhydride, and 4,4′-diamino. It is obtained by reacting a diamine component containing diphenyl ether.

  ADVANTAGE OF THE INVENTION According to this invention, the insulated wire which is excellent in the adhesiveness between a polyimide layer and another part is provided by using the polyimide which has a predetermined composition.

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

[Flat conductor]
The flat conductor 10 has, for example, a rectangular cross section having a width (W) of 2.0 to 7.0 mm and a thickness (H) of 0.7 to 3.0 mm, and includes a copper wire, a copper alloy wire, and an aluminum wire. And composed of a metal wire such as an aluminum alloy wire.

  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 a rectangle) or a rounded shape, the radius of the rounded shape is preferably 0.4 mm or less.

  Examples of the material for the flat conductor 10 include copper, copper alloy, aluminum, aluminum alloy, iron, silver, and alloys thereof. However, from the viewpoint of mechanical strength, conductivity, etc., copper or copper alloy is used. preferable.

[First layer]
The first layer 21 is made of polyimide that does not contain an adhesion improver. Moreover, this polyimide consists of the 1st polyimide or the 2nd polyimide shown below. The first layer 21 is formed by applying and baking a resin varnish capable of forming these polyimides on the flat conductor 10. Hereinafter, the first polyimide and the second polyimide constituting the first layer 21 will be specifically described.

(First polyimide)
The first polyimide is composed of 50 to 90 mol% of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA), 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride ( It is obtained by reacting an acid component composed of 5 to 20 mol% of BTDA and 5 to 40 mol% of pyromellitic anhydride (PMDA) with a diamine component containing 4,4′-diaminodiphenyl ether (DDE).

  As described above, the first polyimide has 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride as acid components. And pyromellitic anhydride. The proportion of each component is 50 to 90 mol% of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic, based on the total acid component. The acid dianhydride is 5 to 20 mol%, and pyromellitic anhydride is 5 to 40 mol%. With such a composition, excellent adhesion is imparted.

  The proportion of each component is preferably 60 to 70 mol% of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-, based on the total acid component. The benzophenone tetracarboxylic dianhydride is 10 to 15 mol%, and pyromellitic anhydride is 25 to 30 mol%.

  The first polyimide uses 4,4'-diaminodiphenyl ether as a diamine component to be reacted with the acid component. For the purposes of the present invention, 4,4'-diaminodiphenyl ether is preferably at least 80 mol%, more preferably at least 90 mol% of the total diamine component. As the diamine component, it is particularly preferable to use 4,4'-diaminodiphenyl ether alone.

  When other diamine components are used in combination, m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 4,4′-diamino-3,3′-dimethyl-1,1′-biphenyl, 4 , 4′-diamino-3,3′-dihydroxy-1,1′-biphenyl, 3,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfone, 4,4 ′ -Diaminodiphenyl sulfide, 2,2-bis (4-aminophenyl) propane, 2,2-bis (4-aminophenyl) hexafluoropropane, 1,3-bis (4-aminophenoxy) benzene, 1,4- Bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, 2,2-bis [4- (4-amino Phenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) The use of aromatic diamines such as phenyl] sulfone is preferred.

  Solvents for reacting the acid component with the diamine component include aprotic polar solvents such as 2-pyrrolidone, N-methyl-2-pyrrolidone (NMP), N, N-dimethylacetamide (DMAc), phenol, cresol. And phenolic solvents such as xylenol.

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

(Second polyimide)
The second polyimide has an acid component composed of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) 50-80 mol% and pyromellitic anhydride (PMDA) 20-50 mol%, It is obtained by reacting with a diamine component containing 4,4′-diaminodiphenyl ether (DDE).

  As described above, the second polyimide uses 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and pyromellitic anhydride as acid components. The ratio of each component is 50 to 80 mol% of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 20 to 50 mol% of pyromellitic anhydride with respect to the total acid component. With such a composition, excellent adhesion is imparted. The proportion of each component is preferably 55 to 65 mol% of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 35 to 45 mol% of pyromellitic anhydride, based on the total acid component. It is.

  The second polyimide uses 4,4'-diaminodiphenyl ether as a diamine component to be reacted with the acid component. For the purposes of the present invention, 4,4'-diaminodiphenyl ether is preferably at least 80 mol%, more preferably at least 90 mol% of the total diamine component. As the diamine component, it is particularly preferable to use 4,4'-diaminodiphenyl ether alone.

  When other diamine components are used in combination, m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 4,4′-diamino-3,3′-dimethyl-1,1′-biphenyl, 4 , 4′-diamino-3,3′-dihydroxy-1,1′-biphenyl, 3,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfone, 4,4 ′ -Diaminodiphenyl sulfide, 2,2-bis (4-aminophenyl) propane, 2,2-bis (4-aminophenyl) hexafluoropropane, 1,3-bis (4-aminophenoxy) benzene, 1,4- Bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, 2,2-bis [4- (4-amino Phenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) The use of aromatic diamines such as phenyl] sulfone is preferred.

  Solvents for reacting the acid component with the diamine component include aprotic polar solvents such as 2-pyrrolidone, N-methyl-2-pyrrolidone (NMP), N, N-dimethylacetamide (DMAc), phenol, cresol. And phenolic solvents such as xylenol.

  When the acid component and the diamine component are reacted, a reaction catalyst 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 first layer 21 does not contain an adhesion improver. Since it does not contain an adhesion improver, thermal deterioration during use is suppressed, and a decrease in adhesion between the first layer 21 and a portion adjacent thereto is suppressed.

  Examples of the adhesion improver include thiadiazole, thiazole, mercaptobenzimidazole, thiophenol, thiophene, thiol, tetrazole, benzimidazole, butylated melamine, heterocyclic mercaptan and the like.

[Second layer]
The second layer 22 is made of polyamideimide. The second layer 22 is formed by applying and baking a resin varnish capable of forming polyamideimide on the first layer 21.

  The polyamideimide constituting the second layer 22 is obtained by reacting an acid component with an isocyanate component containing 2,4′-diphenylmethane diisocyanate (2,4′-MDI) and dimer acid diisocyanate (DDI). Those are preferred.

  By using 2,4'-diphenylmethane diisocyanate and dimer acid diisocyanate as the isocyanate component, the flexibility of the second layer 22 is improved. The total of 2,4'-diphenylmethane diisocyanate and dimer acid diisocyanate is preferably 10 to 70 mol%, more preferably 30 to 60 mol% of the isocyanate component.

  Other isocyanate components used in combination include 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, vitorylene diisocyanate, dianisidi diisocyanate, isomers thereof, and the like. . 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 their isomers, butanetetracarboxylic dianhydrides, 5- (2,5-dioxotetrahydro-3-furanyl) Tricarboxylic acids such as alicyclic tetracarboxylic dianhydrides such as -3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride, trimesic acid, tris (2-carboxyethyl) isocyanurate (CIC acid), etc. And isomers thereof. Among these, trimellitic anhydride (TMA) that is inexpensive and excellent in safety is preferable.

  Moreover, you may add polycarboxylic acid other than an isocyanate component and an acid component. 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 the 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 (DMAc), phenol And phenolic solvents such as cresol and 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.

[Third layer]
The third layer 23 is made of the following first polyimide or second polyimide. The third layer 23 is formed by applying and baking a resin varnish capable of forming them on the second layer 22. Hereinafter, the first polyimide and the second polyimide constituting the third layer 23 will be specifically described.

(First polyimide)
The first polyimide is composed of 50 to 90 mol% of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA), 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride ( It is obtained by reacting an acid component composed of 5 to 20 mol% of BTDA and 5 to 40 mol% of pyromellitic anhydride (PMDA) with a diamine component containing 4,4′-diaminodiphenyl ether (DDE).

  As described above, the first polyimide has 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride as acid components. And pyromellitic anhydride. The proportion of each component is 50 to 90 mol% of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic, based on the total acid component. The acid dianhydride is 5 to 20 mol%, and pyromellitic anhydride is 5 to 40 mol%. With such a composition, excellent adhesion is imparted.

  The proportion of each component is preferably 60 to 70 mol% of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-, based on the total acid component. The benzophenone tetracarboxylic dianhydride is 10 to 15 mol%, and pyromellitic anhydride is 25 to 30 mol%.

  The first polyimide uses 4,4'-diaminodiphenyl ether as a diamine component to be reacted with the acid component. For the purposes of the present invention, 4,4'-diaminodiphenyl ether is preferably at least 80 mol%, more preferably at least 90 mol% of the total diamine component. As the diamine component, it is particularly preferable to use 4,4'-diaminodiphenyl ether alone.

  When other diamine components are used in combination, m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 4,4′-diamino-3,3′-dimethyl-1,1′-biphenyl, 4 , 4′-diamino-3,3′-dihydroxy-1,1′-biphenyl, 3,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfone, 4,4 ′ -Diaminodiphenyl sulfide, 2,2-bis (4-aminophenyl) propane, 2,2-bis (4-aminophenyl) hexafluoropropane, 1,3-bis (4-aminophenoxy) benzene, 1,4- Bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, 2,2-bis [4- (4-amino Phenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) The use of aromatic diamines such as phenyl] sulfone is preferred.

  Solvents for reacting the acid component with the diamine component include aprotic polar solvents such as 2-pyrrolidone, N-methyl-2-pyrrolidone (NMP), N, N-dimethylacetamide (DMAc), phenol, cresol. And phenolic solvents such as xylenol.

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

(Second polyimide)
The second polyimide has an acid component composed of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) 50-80 mol% and pyromellitic anhydride (PMDA) 20-50 mol%, It is obtained by reacting with a diamine component containing 4,4′-diaminodiphenyl ether (DDE).

  As described above, the second polyimide uses 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and pyromellitic anhydride as acid components. The ratio of each component is 50 to 80 mol% of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 20 to 50 mol% of pyromellitic anhydride with respect to the total acid component. With such a composition, excellent adhesion is imparted. The proportion of each component is preferably 55 to 65 mol% of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 35 to 45 mol% of pyromellitic anhydride, based on the total acid component. It is.

  The second polyimide uses 4,4'-diaminodiphenyl ether as a diamine component to be reacted with the acid component. For the purposes of the present invention, 4,4'-diaminodiphenyl ether is preferably at least 80 mol%, more preferably at least 90 mol% of the total diamine component. As the diamine component, it is particularly preferable to use 4,4'-diaminodiphenyl ether alone.

  When other diamine components are used in combination, m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 4,4′-diamino-3,3′-dimethyl-1,1′-biphenyl, 4 , 4′-diamino-3,3′-dihydroxy-1,1′-biphenyl, 3,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfone, 4,4 ′ -Diaminodiphenyl sulfide, 2,2-bis (4-aminophenyl) propane, 2,2-bis (4-aminophenyl) hexafluoropropane, 1,3-bis (4-aminophenoxy) benzene, 1,4- Bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, 2,2-bis [4- (4-amino Phenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) The use of aromatic diamines such as phenyl] sulfone is preferred.

  Solvents for reacting the acid component with the diamine component include aprotic polar solvents such as 2-pyrrolidone, N-methyl-2-pyrrolidone (NMP), N, N-dimethylacetamide (DMAc), phenol, cresol. And phenolic solvents such as xylenol.

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

  It is preferable that the 3rd layer 23 does not contain an adhesive improvement agent. By not containing an adhesion improver, thermal deterioration during use is suppressed, and a decrease in adhesion between the third layer 23 and a portion adjacent thereto is suppressed.

  Examples of the adhesion improver include thiadiazole, thiazole, mercaptobenzimidazole, thiophenol, thiophene, thiol, tetrazole, benzimidazole, butylated melamine, heterocyclic mercaptan and the like.

  The type of polyimide constituting the third layer 23 may be the same as or different from the type of polyimide constituting the first layer 21. For example, the first layer 21 and the third layer 23 may be made of a first polyimide, and the first layer 21 and the third layer 23 may be made of a second polyimide.

  When the 1st layer 21 and the 3rd layer 23 are comprised with the 1st polyimide, the composition of the 1st polyimide in these layers may mutually be the same, and may differ. The same applies to the case where the first layer 21 and the third layer 23 are made of the second polyimide.

  In addition, the first layer 21 may be made of the first polyimide, the third layer 23 may be made of the second polyimide, the first layer 21 may be made of the second polyimide, The layer 23 may be made of the first polyimide.

  The first layer 21, the second layer 22, and the third layer 23 are each formed by sequentially applying and baking a resin varnish on the flat conductor 10. The method of applying and baking each resin varnish is not particularly limited. For example, a flat conductor 10 or the first layer 21 or the second layer 22 is formed in a bath containing the resin varnish. After passing the flat rectangular conductor 10, a method of baking in a baking furnace or the like can be used.

  The thickness (T) of the insulating film 20, that is, the total thickness of the first layer 21, the second layer 22, and the third layer 23 (t1, t2, and t3) is 60 to 200 μm. Is preferred. When the thickness (T) of the insulating film 20 is 60 μm or more, the partial discharge start voltage increases. Further, when the thickness (T) of the insulating film 20 is 200 μm or less, the insulating film 20 becomes thin, so that the coil is downsized. The thickness (T) of the insulating film 20 is more preferably 60 to 160 μm.

  The ratio of each layer to the thickness of the insulating film 20 is preferably 10 to 25% for the first layer 21, 10 to 75% for the second layer 22, and 10 to 75% for the third layer 23. When the thickness of the first layer 21 is within the above range, the adhesion between the flat conductor 10 and the second layer 22 that are adjacent portions is improved. When the thickness of the second layer 22 is within the above range, the workability is good. Moreover, when the thickness of the 3rd layer 23 exists in the said range, adhesiveness with the 2nd layer 22 which is an adjacent part becomes favorable.

  According to the flat enameled wire 1 of the present embodiment, since the first layer 21 and the third layer 23 made of polyimide are provided so as to sandwich the second layer 22 made of polyamideimide, the polyamideimide The deterioration of the second layer 22 made of is suppressed, and the mechanical characteristics and the like are favorably maintained.

  That is, polyimide generally has resistance to oil and the like. Therefore, by providing the third layer 23 made of polyimide outside the second layer 22 made of polyamideimide, deterioration of the second layer 22 made of polyamideimide due to contact with oil or the like is suppressed.

  Moreover, even if the flat conductor 10 is oxidized and the flat conductor 10 and the first layer 21 are peeled off, and the oil or the like soaks into the peeled portion, the first layer 21 is made of polyimide. Thus, deterioration of the second layer 22 made of polyamideimide due to contact with oil or the like is suppressed.

  Also, even if the second layer 22 made of polyamideimide deteriorates, the first layer 21 made of polyimide and the third layer 23 provided on both sides of the second layer 22 made of polyamideimide are The mechanical properties and the like are maintained well by being reinforced.

  In particular, according to the flat enameled wire 1 of the present embodiment, since the first layer 21 and the third layer 23 are made of polyimide having a specific composition, the first layer 21 and the third layer 23 Excellent adhesion between other parts. As a result, even when used in a harsh environment, the deterioration or the like of the second layer 22 made of polyamideimide is suppressed, and the mechanical characteristics and the like are maintained well.

  Specifically, since the adhesion between the first layer 21 and the third layer 23 and other portions is excellent, the environment is high temperature and high humidity environment, high vibration environment, insulating oil, machine oil, engine oil, transmission. Even when used in harsh environments, such as in contact with oils such as oil and / or water, the deterioration of the second layer 22 made of polyamideimide is suppressed, and the mechanical characteristics and the like are maintained well. Is done.

  Thus, since the flat enameled wire 1 of this embodiment is suitable for use in a harsh environment, it is preferably used for automobile parts. In particular, the flat enameled wire 1 of the present embodiment is preferably used for a motor of an automobile.

  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, although the above embodiment is an example in which the present invention is applied to a flat enameled wire in which a flat conductor is used, it goes without saying that the present invention can be applied to a round enameled wire in which a circular conductor is used.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

[Preparation of polyimide resin varnish (A1 to A7)]
In a flask equipped with a stirrer, a nitrogen inflow pipe and a heating / cooling device, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (as acid component) was used so as to have the ratio shown in Table 1. BPDA), 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride (BTDA), pyromellitic anhydride (PMDA), 4,4′-diaminodiphenyl ether (DDE) as diamine component, improved adhesion Mercaptobenzimidazole was added as an agent. Thereafter, 400 parts by mass of N-methyl-2-pyrrolidone as a solvent with respect to a total of 100 parts by mass of the acid component and the diamine component was added and reacted for 2 hours with stirring in a nitrogen atmosphere to obtain polyimide resin varnishes (A1 to A7). )

  The polyimide resin varnish (A1 to A4) forms the first polyimide in the present invention, and the polyimide resin varnish (A5 to A7) forms both the first polyimide and the second polyimide in the present invention. It is something that does not.

[Preparation of polyimide resin varnish (B1 to B6)]
In a flask equipped with a stirrer, a nitrogen inflow pipe and a heating / cooling device, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (as acid component) was used so as to have the ratio shown in Table 2. BPDA), pyromellitic anhydride (PMDA), and 4,4′-diaminodiphenyl ether (DDE) were added as diamine components. Thereafter, 400 parts by mass of N-methyl-2-pyrrolidone as a solvent is added to 100 parts by mass of the total of the acid component and the diamine component, and reacted for 2 hours in a nitrogen atmosphere to obtain polyimide resin varnishes (B1 to B6). It was.

  The polyimide resin varnish (B1 to B4) forms the second polyimide in the present invention, and the polyimide resin varnish (B5 to B6) forms both the first polyimide and the second polyimide in the present invention. It is something that does not.

[Preparation of polyamideimide resin varnish (C)]
2,4′-diphenylmethane diisocyanate (2,4′-MDI), dimer acid as an isocyanate component in a flask equipped with a stirrer, a nitrogen inflow pipe and a heating / cooling device so as to have the ratio shown in Table 3 Diisocyanate (DDI), 4,4′-diphenylmethane diisocyanate (4,4′-MDI), and trimellitic anhydride (TMA) were added as acid components. Thereafter, 150 parts by mass of N-methyl-2-pyrrolidone as a solvent is added to 100 parts by mass of the acid component and the isocyanate component, and the temperature is raised from room temperature to 140 ° C. over 2 hours while stirring in a nitrogen atmosphere. After reacting at this temperature for 3 hours, it was diluted with 83 parts by mass of N, N-dimethylformamide (DMF) and cooled to room temperature to obtain a polyamideimide resin varnish (C1 to C3).

[Examples 1 to 6]
As shown in Table 4, polyimide resin varnishes (A1 to A4) were applied and baked on a rectangular copper conductor having a thickness of 1.9 mm and a width of 3.4 mm to form a 20 μm-thick film (first layer). Next, a polyamideimide resin varnish (C1 to C3) was applied and baked on the first layer to form a 60 μm thick film (second layer). Further, a polyimide resin varnish (A1 to A4) was applied on the second layer and baked to form a 20 μm thick film (third layer) to obtain an insulated wire.

[Examples 7 to 10]
As shown in Table 5, an insulated wire was obtained in the same manner as in Example 1 except that polyimide resin varnishes (B1 to B4) were used for forming the first layer and the third layer.

[Comparative Examples 1-5]
An insulated wire was obtained in the same manner as in Example 1 except that the polyimide resin varnish (A5 to A7) or the polyimide resin varnish (B5 to B6) was used for forming at least one of the first layer and the third layer.

[Comparative Example 6]
An insulated wire was obtained in the same manner as in Example 1 except that a commercially available polyimide resin varnish (trade name: Torenice # 3000) was used to form the first layer and the third layer.

  Then, about the insulated wire of the Example and the comparative example, the adhesive force (g / mm) of a conductor and a 1st layer (polyimide layer) was measured by the 180 degree peeling test.

  Moreover, the adhesive force (g / mm) of a 1st layer (polyimide layer) and a 2nd layer (polyamideimide layer) was measured by the 180 degree peeling test about the insulated wire after 250 degreeC 48-hour heat deterioration.

  These measurement results are shown in Tables 4-5. In the table, for adhesion, “◎” indicates adhesion strength of more than 50 g / mm, and “◯” indicates 30 g / mm or more and 50 g / mm or less.

  The insulated wire of an Example is excellent in the adhesiveness between the conductor and the 1st layer which consists of polyimides, and the adhesiveness between the 1st layer which consists of polyimides, and the 2nd layer which consists of polyamideimides. However, in the insulated wire of the comparative example, the adhesion strength after heating between the first layer made of polyimide and the second layer made of polyamideimide was less than 30 g / mm, and the desired adhesion could not be obtained. .

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

Claims (7)

On the conductor, there is a first layer made of polyimide that does not contain an adhesion improver, a second layer made of polyamideimide, and a third layer made of polyimide in this order,
The polyimides constituting the first layer and the third layer are independent of each other,
3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride 50-90 mol%, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride 5-20 mol% and pyromellitic anhydride A first polyimide obtained by reacting an acid component consisting of 5 to 40 mol% with a diamine component containing 4,4′-diaminodiphenyl ether, or
An acid component composed of 50 to 80 mol% of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 20 to 50 mol% of pyromellitic anhydride, and a diamine component containing 4,4′-diaminodiphenyl ether A second polyimide obtained by reacting
An insulated wire comprising:   The first polyimide comprises 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride 60 to 70 mol%, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride 10-15. The insulated wire according to claim 1, wherein the insulated wire is obtained by reacting an acid component composed of 25 mol% of pyromellitic anhydride and 25-30 mol% of pyromellitic anhydride with a diamine component containing 4,4'-diaminodiphenyl ether.   The second polyimide comprises an acid component consisting of 55 to 65 mol% 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride and 35 to 45 mol% pyromellitic anhydride, and 4,4'- The insulated wire according to claim 1, wherein the insulated wire is obtained by reacting a diamine component containing diaminodiphenyl ether.   The polyamideimide constituting the second layer is obtained by reacting an isocyanate component containing a total of 10 to 70 mol% of 2,4'-diphenylmethane diisocyanate and dimer acid diisocyanate with an acid component. Item 4. The insulated wire according to any one of Items 1 to 3.   The first layer is 10 to 25% and the second layer is 10 to 75% with respect to the total thickness of the insulating film composed of the first layer, the second layer, and the third layer. The insulated wire according to any one of claims 1 to 4, wherein the third layer is 10 to 75%.   The insulated wire according to any one of claims 1 to 5, wherein the total thickness of the insulating film composed of the first layer, the second layer, and the third layer is 60 to 200 µm. .   The insulated wire according to any one of claims 1 to 6, wherein the conductor is a flat conductor.

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