WO2016009998A1

WO2016009998A1 - Insulated covered aluminum wire

Info

Publication number: WO2016009998A1
Application number: PCT/JP2015/070065
Authority: WO
Inventors: 亮介小比賀; 真大矢
Original assignee: 古河電気工業株式会社; 古河マグネットワイヤ株式会社
Priority date: 2014-07-14
Filing date: 2015-07-13
Publication date: 2016-01-21
Also published as: JP6012672B2; JP2016021324A

Abstract

An insulated covered aluminum wire which comprises, on the outer circumference of a conductor, an insulating covering layer that contains a resin having at least a benzene ring and an imide ring, and which is covered by two or more insulating covering layers. The resin which constitutes the innermost insulating covering layer that is in contact with the conductor has a molar ratio of the imide ring content to the benzene ring content of 0.366 or more as determined by formula (1). In addition, the absolute value of the difference of the above-described molar ratio of the imide ring content of the constituent resin between adjacent insulating covering layers is more than 0 but 0.167 or less with respect to any two adjacent insulating covering layers. Total number of moles of imide rings in resin/total number of moles of benzene rings in resin formula (1)

Description

Insulation coated aluminum wire

The present invention relates to an insulation-coated aluminum electric wire, especially a multi-layer insulation-coated aluminum electric wire having an insulating film excellent in winding workability for constructing a coil of a motor, a generator, etc., and in particular, optimum adhesion.

In recent years, with the reduction in weight and size of coils used in motors and generators, especially the conductors such as coils used in these have been strongly required to be reduced in weight. For this reason, adoption of aluminum or aluminum alloy whose specific gravity is 1/3 or less of copper is examined.

In addition to this, there is a demand for improvement in winding workability and heat resistance of the insulating film. However, since an aluminum conductor tends to form an oxide film, its adhesiveness with a coating resin tends to be inferior to copper. Also, since the tensile strength of the conductor is small compared to copper, there is a problem that when an aluminum conductor is used and coil winding is performed, larger elongation or conductor deformation is likely to occur, and the insulation of the insulating film is reduced. Yes, it is necessary to satisfy the tight winding workability, the adhesion to the aluminum conductor, the interlayer adhesion of the coating resin, and the insulation after processing.
Conventionally, it has been proposed to use polyamideimide or polyimide as an insulating layer, or to use a resin blended with polyimide as part of an insulating film (see, for example, Patent Documents 1 to 5). However, the prior art does not sufficiently satisfy the need for strict winding workability. That is, in the conventional insulating film, the adhesion between the aluminum conductor and the insulating film is not sufficient. In addition, when the insulation coating is formed of a resin having the same composition, the adhesion between the insulation coating resin layers becomes too high, and scratches generated in any layer due to winding processing spread in the lamination direction of the insulation coating resin layer, and insulation There was a problem that the performance decreased. On the other hand, if the adhesion between the insulating coating resin layers is too low, there is a concern that the wear resistance deteriorates.

Japanese Patent Laying-Open No. 2005-079934 JP 2005-302597 A JP 2005-302598 A JP 2008-013635 A JP 2008-016266 A

As described above, when the conductors are copper and aluminum, the performance differs greatly. Therefore, the knowledge obtained with the copper conductor cannot be used as it is.
Therefore, in order to meet the demands for strict winding workability, the present invention provides adhesion to an aluminum conductor, adhesion between insulating coating resin layers, wear resistance (winding workability of an insulating film), and insulation after processing. An object of the present invention is to provide an insulating coated aluminum electric wire with high performance.

As a result of various investigations of various insulating coating resins, the present inventors are excellent in coating resins made of polyamideimide resin, polyimide resin, and polyamide resin, and in particular, the molar ratio of imide ring to benzene ring in the coating resin is important. I found out. In particular, by providing a resin having a high imide ring-containing molar ratio in the innermost layer in contact with the aluminum conductor, adhesion with the aluminum conductor can be satisfied, and the imide ring-containing molar ratio is specified between the coating resin layers. It was found that, in addition to the adhesiveness with the aluminum conductor, the adhesiveness between the insulating coating resin layers, the wear resistance, and the post-processing insulation were excellent. The present invention has been made based on this finding.

That is, the said subject was solved by the following means.
(1) An insulating coated aluminum electric wire having an insulating coating layer containing at least a resin having a benzene ring and an imide ring on the outer periphery of the conductor and covering two or more insulating coating layers, In the insulating coating layers adjacent to each other, the imide ring-containing molar ratio of the resin constituting the innermost insulating coating layer in contact with the benzene ring determined by the following formula (1) is 0.366 or more. An insulation-coated aluminum electric wire characterized in that the absolute value of the difference in the imide ring-containing molar ratio of the constituent resin is more than 0 and 0.167 or less in any adjacent insulation coating layer.

Total number of imide rings in resin / Total number of moles of benzene ring Formula (1)

(2) The insulation-coated aluminum electric wire according to (1), wherein an absolute value of the difference in the imide ring-containing molar ratio is 0.033 or more and 0.167 or less.
(3) The (1) or (2) is characterized in that the imide ring-containing molar ratio in the resin constituting the innermost insulating coating layer in contact with the conductor is 0.366 to 0.634. The insulation-coated aluminum electric wire described.
(4) Of all the insulating coating layers, the absolute value of the difference between the maximum value and the minimum value of the imide ring-containing molar ratio is more than 0 and 0.30 or less (1) to ( The insulation-coated aluminum electric wire according to any one of 3).
(5) The absolute value of the difference between the maximum value and the minimum value of the imide ring-containing molar ratio among all the insulating coating layers is 0.033 or more and 0.300 or less (1) to The insulation-coated aluminum electric wire according to any one of (4).
(6) The imide ring-containing molar ratio of the resin constituting the insulating coating layer is the largest in the innermost insulating coating layer in contact with the conductor and the smallest in the outermost insulating coating layer farthest from the conductor The insulation-coated aluminum electric wire according to any one of (1) to (5), wherein
(7) Among the two or more insulating coating layers, the thickness of the innermost insulating coating layer in contact with the conductor is the same as or thinner than the thickness of any of the remaining insulating coating layers. The insulation-coated aluminum electric wire according to any one of (1) to (6), wherein
(8) The insulation-coated aluminum according to any one of (1) to (7), wherein the thickness of at least one of the two or more insulation coating layers is more than 0 μm and 25 μm or less. Electrical wire.
(9) The insulation-coated aluminum electric wire according to any one of (1) to (8), wherein the resin contained in the insulation coating layer is a mixture of a polyamideimide resin and a polyimide resin.

According to the present invention, an insulation-coated aluminum electric wire having high adhesion to an aluminum conductor, adhesion between insulating coating resin layers, wear resistance, and high insulation after processing can be provided in order to meet the demand for severe winding workability.
In particular, by providing a resin with a high imide ring-containing molar ratio in the innermost layer in contact with the aluminum conductor, it is possible to satisfy the adhesiveness with the aluminum conductor, and the specific relationship of the imide ring-containing molar ratio between the coated resin layers Preferably, the imide ring-containing molar ratio is lowered sequentially from the conductor side, so that in addition to the adhesion to the aluminum conductor, the adhesion between the insulating coating resin layers, the wear resistance, and the insulation after processing are excellent.

In addition, “to” used in this specification includes numerical values described before and after the upper limit value and the lower limit value.
In addition, the “layer” in the present invention means a layer in which the resin and the additive to be contained are laminated adjacent to each other, and includes a layer composed of one layer or a plurality of layers.
The above and other features and advantages of the present invention will become more apparent from the following description, with reference where appropriate to the accompanying drawings.

FIG. 1 is a schematic cross-sectional view of an insulation-coated aluminum electric wire of the present invention. FIG. 2 is a chart of the infrared absorption spectrum of the polyimide resin measured in the examples.

Hereinafter, embodiments of the present invention will be described in detail.
The insulation-coated aluminum electric wire of the present invention is an insulation-coated aluminum electric wire having an insulation coating layer containing a resin having at least a benzene ring and an imide ring on the outer periphery of a conductor and covering two or more insulation coating layers. The imide ring-containing molar ratio of the resin constituting the innermost insulating coating layer in contact with the conductor to benzene is 0.366 or more, and the imide of the resin constituting the layer in the insulating coating layers adjacent to each other The absolute value of the difference in the ring-containing molar ratio is more than 0 and 0.167 or less in any adjacent insulating coating layer.
Hereinafter, materials and materials used in the present invention will be described.

<Conductor>
The aluminum of the conductor used in the present invention is pure aluminum or an aluminum alloy (in the present specification, these may be simply referred to as aluminum). Such a conductor may be any pure aluminum or aluminum alloy conventionally used in electric wires. Examples of the aluminum alloy include a 1000 series aluminum alloy, a 2000 series aluminum alloy, a 3000 series aluminum alloy, a 4000 series aluminum alloy, a 5000 series aluminum alloy, and a 6000 series aluminum alloy. An aluminum alloy containing 6 mass% or less, Si being 0.2 to 1.0 mass%, Mg being 0.2 to 1.0 mass%, the balance being aluminum and inevitable impurities.
Among pure aluminum and aluminum alloys, 1000 series aluminum alloys having an aluminum purity of 99% or more are preferable, and those having high electrical conductivity are preferable.

Since the cross-sectional shape of the aluminum conductor is determined according to the application, it may be any shape such as a circle, a flat (rectangular) shape, or a hexagonal shape. For applications such as a rotating electrical machine, for example, a rectangular conductor is preferable in that the occupation ratio of the conductor in the status lot can be increased.
The size of the conductor is determined according to the use and is not particularly specified. However, in the case of a round conductor, the diameter is preferably 0.3 mm to 3.0 mm, more preferably 0.4 mm to 2.7 mm. In the case of a rectangular conductor, the length of one side (width (long side)) is preferably 1.0 mm to 5.0 mm, more preferably 1.4 mm to 4.0 mm, and the thickness (short side) is 0.4 mm to 3 mm. 0.0 mm is preferable, and 0.5 mm to 2.5 mm is more preferable. However, the range of the conductor size in which the effect of the present invention can be obtained is not limited to this. In the case of a flat rectangular conductor, this also varies depending on the application, but a rectangular cross section is more common than a square cross section. When the application is a rotating electrical machine, the chamfering (curvature radius r) of the four corners of the flat rectangular conductor cross section is preferably smaller r from the viewpoint of increasing the conductor occupancy in the status lot. From the viewpoint of suppressing the partial discharge phenomenon due to the electric field concentration on the surface, r is preferably larger. Therefore, the curvature radius r is preferably 0.6 mm or less, and more preferably 0.2 mm to 0.4 mm. However, the range in which the effect of the present invention can be obtained is not limited to this.

<Insulation coating layer>
In the present invention, the insulating coating layer is a laminated resin coating layer composed of two or more insulating coating layers.
The insulating coating layer is preferably 2 to 10 layers, more preferably 2 to 6 layers, and even more preferably 2 to 5 layers.
Further, when the thickness of at least one of the two or more insulating coating layers is 25 μm or less, that is, more than 0 μm and 25 μm or less, the dielectric breakdown voltage (BDV) after stretching is excellent. Further, 0.1 to 10 μm is more preferable.
Of these, the thickness of each of the two or more insulating coating layers is preferably more than 0 μm and 25 μm or less, and more preferably 0.1 to 10 μm.
In the present invention, the thickness of each insulating layer is set such that the thickness of the innermost insulating coating layer in contact with the conductor is the same as or thinner than the thickness of any remaining insulating coating layer. Excellent BDV after stretching.
In particular, the thickness of the innermost insulating coating layer in contact with the conductor is preferably 0.1 to 10 μm.
On the other hand, the total thickness of the insulating coating layer is preferably 10 to 100 μm and more preferably 20 to 80 μm because of excellent adhesion, abrasion resistance and post-processing insulation.

In the present invention, the resin constituting the insulating coating layer is a resin having at least a benzene ring and an imide ring, and the innermost insulating coating layer in contact with the conductor is made of the resin.
Resins having at least a benzene ring and an imide ring include, for example, polyimide resin (PI) [in this specification, including peripheral resins such as polyetherimide resin (PEI) and polyesterimide resin], polyamideimide resin (PAI) As such, it may be a single resin, a mixture of these resins, or a mixture with other resins. In this invention, since it is excellent in abrasion resistance, the resin which mixed the polyimide resin (PI) and the polyamide-imide resin (PAI) is further more preferable.

The polyimide resin (PI) can be synthesized by reacting tetracarboxylic dianhydride with polyvalent amines having two or more amine groups in one molecule.
Polyamideimide resin (PAI) is obtained by, for example, a method of directly reacting a tricarboxylic acid anhydride with a polyvalent isocyanate having two or more isocyanate groups in one molecule in an organic solvent, or in a polar solvent. Then, the tricarboxylic acid anhydride and the polyvalent amine having two or more amine groups in one molecule are reacted first to introduce an imide bond first, and then two or more isocyanate groups in one molecule. It can be produced by a method of amidation with a polyisocyanate having.
The polyamide resin (PA) can be synthesized by reacting dicarboxylic acid, diester of dicarboxylic acid or dihalide of dicarboxylic acid with polyvalent amines having two or more amine groups in one molecule.

Examples of the tetracarboxylic dianhydride include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA), 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride ( BTDA), 3,3 ′, 4,4′-biphenyl ether tetracarboxylic dianhydride (OPDA), 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic dianhydride (DSDA), bicyclo (2 , 2,2) -Oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BCD), 1,2,4,5-cyclohexanetetracarboxylic dianhydride (H-PMDA) , Pyromellitic dianhydride (PMDA), 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA), 5- (2,5-dioxotetrahydrofuryl) Methyl-3-cyclohexene-1,2-dicarboxylic anhydride (CP) and the like.

Examples of the tricarboxylic acid anhydride include trimellitic acid anhydride (TMA), 2- (3,4-dicarboxyphenyl) -2- (3-carboxyphenyl) propane anhydride, and (3,4-dicarboxyphenyl). ) (3-carboxyphenyl) methane anhydride, (3,4-dicarboxyphenyl) (3-carboxyphenyl) ether anhydride, 3,3 ′, 4-tricarboxybenzophenone anhydride, 1,2,4-butane Tricarboxylic acid anhydride, 2,3,5-naphthalene tricarboxylic acid anhydride, 2,3,6-naphthalene tricarboxylic acid anhydride, 1,2,4-naphthalene tricarboxylic acid anhydride, 2,2 ′, 3-biphenyltricarboxylic acid An acid anhydride is mentioned.

Dicarboxylic acids include terephthalic acid, isophthalic acid, 2,2′-biphenyldicarboxylic acid, 2,2-bis (3-carboxyphenyl) propane, bis (3-carboxyphenyl) methane, bis (3-carboxyphenyl) ether 3,3′-dicarboxybenzophenone, dibasic acids such as succinic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid and the like.

Examples of the polyvalent isocyanate having two or more isocyanate groups in one molecule include aliphatic, alicyclic, araliphatic, aromatic or heterocyclic polyisocyanates. Specifically, ethylene diisocyanate, 1 , 4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,12-dodecane diisocyanate, cyclobutene-1,3-diisocyanate, cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, isophorone diisocyanate, 1 , 3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane-2,4′-diisocyanate, diphenylmethane-4, '-Diisocyanate (MDI), diphenyl ether-4,4'-diisocyanate, xylylene diisocyanate, naphthalene-1,5-diisocyanate, 1-methoxybenzene-2,4-diisocyanate, 1-methoxybenzene-2,4-diisocyanate, Examples thereof include diphenylsulfone-4,4′-diisocyanate, a compound having three or more isocyanate groups in one molecule obtained by multiplying these diisocyanates, and polyphenylmethylene polyisocyanate.

Examples of diamines include p-phenylene diamine, m-phenylene diamine, silicone diamine, bis (3-aminopropyl) ether ethane, 3,3′-diamino-4,4′-dihydroxydiphenyl sulfone (SO ₂ -HOAB), 4 , 4′-diamino-3,3′-dihydroxybiphenyl (HOAB), 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane (HOCF ₃ AB), siloxane diamine, bis (3-amino Propyl) ether ethane, N, N-bis (3-aminopropyl) ether, 1,4-bis (3-aminopropyl) piperazine, isophoronediamine, 1,3-bis (aminomethyl) cyclohexane, 3,3′- Dimethyl-4,4′-diaminodicyclohexylmethane, 4,4′-methylenebis ( Cyclohexylamine), 4,4'-diaminodiphenyl ether (DDE), 3,4'-diaminodiphenyl ether (m-DDE), 3,3'-diaminodiphenyl ether, 4,4'-diamino-diphenyl sulfone (p-DDS) ), 3,4′-diamino-diphenylsulfone, 3,3′-diamino-diphenylsulfone, 2,4′-diaminodiphenyl ether, 1,3-bis (4-aminophenoxy) benzene (m-TPE), 1, 3-bis (3-aminophenoxy) benzene (APB), 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP), 2,2-bis [4- (4-aminophenoxy) phenyl ] Hexafluoropropane (HF-BAPP), bis [4- (4-aminophenoxy) phenyl] sulfone (p- APS), bis [4- (3-aminophenoxy) phenyl] sulfone (m-BAPS), 4,4′-bis (4-aminophenoxy) biphenyl (BAPB), 1,4-bis (4-aminophenoxy) Benzene (p-TPE), 4,4′-diaminodiphenyl sulfide (ASD), 3,4′-diaminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfide, 3,3′-diamino-4,4′-dihydroxy Diphenylsulfone, 2,4-diaminotoluene (DAT), 2,5-diaminotoluene, 3,5-diaminobenzoic acid (DABz), 2,6-diaminopyridine (DAPy), 4,4′-diamino-3, 3′-dimethoxybiphenyl (CH ₃ OAB), 4,4′-diamino-3,3′-dimethylbiphenyl (CH ₃ AB), 9,9′-bis (4-aminophenyl) fluorene (FDA) and the like.

The mass average molecular weights of the polyimide resin (PI) and the polyamideimide resin (PAI) are preferably 5,000 to 100,000, and more preferably 10,000 to 50,000.
Here, the mass average molecular weight is a value determined in terms of polystyrene by GPC (Gel Permeation Chromatography).

Examples of the polyimide resin (PI) include I.K. S. Pire-ML (trade name) manufactured by T Company, Trenys # 3000 (trade name) manufactured by Toray Industries, Inc., Uimide (trade name) manufactured by Unitika Ltd., Aurum manufactured by Mitsui Chemicals, Inc. PL450C and the like are listed, and are also classified as SABIC innovative Plastic IP BV Ultem (trade name) and polyesterimide resin (synthesized from trimellitic anhydride, diamine), which are classified as polyetherimide resin (PEI). Examples include Terebec 850 (trade name) manufactured by Nissei Kasei Co., Ltd., and Isomi RL (trade name) manufactured by Nissho Schenectaday Chemical Co., Ltd.
Examples of the polyamide-imide resin (PAI) include HI406 and HI-404 (both trade names) manufactured by Hitachi Chemical Co., Ltd., and AI352 and AI301 manufactured by Arakawa Chemical Co., Ltd.

Other resins include polyamide resin (PA), polyphenylsulfone resin (PPSU), polyethersulfone resin (PES), polyphenylene ether resin (PPE), polyetheretherketone resin (PEEK), polyphenylene sulfide resin (PPS). , Polyketone resin (PK), polysulfone resin (PSU) and the like.
Examples of the polyethersulfone resin (PES) include Sumika Excel 3600G, 4100G, and 4800G manufactured by Sumitomo Chemical Co., Ltd.

(Imide ring-containing molar ratio of the resin constituting the insulating coating layer to the benzene ring)
In the present invention, the imide ring-containing molar ratio of the resin constituting the innermost insulating coating layer in contact with the conductor to the benzene ring determined by the following formula (1) is 0.366 or more, and adjacent to each other In the layer, the absolute value of the difference in the imide ring-containing molar ratio of the resin constituting the layer is more than 0 and 0.167 or less in any adjacent insulating coating layer.

For example, in the polyimide resin (PI) obtained from pyromellitic dianhydride (PMDA) and 4,4′-diaminodiphenyl ether (DDE), there is no amide group, only an imide group, and the above formula (1) The molar ratio of the imide ring to the benzene ring determined in (2) is 2 / 3≈0.667. Further, in the polyamideimide resin (PAI) obtained from trimellitic anhydride (TMA) and diphenylmethane-4,4′-diisocyanate (MDI), the imide group and the amide group are present in a ratio of 1: 1. The molar ratio of the imide ring to the benzene ring determined in 1) is 1 / 3≈0.333.

By making the imide ring-containing molar ratio with respect to the benzene ring present in the resin constituting the insulating coating layer in contact with the aluminum conductor to be 0.366 or more, the intermolecular force between the imide ring and the surface of the aluminum conductor becomes strong, It is estimated that the adhesion with the aluminum conductor is improved. On the other hand, in the adjacent insulating coating layers, the adjacent insulating coating layers have a laminated structure in which the absolute value of the difference in the imide ring-containing molar ratio is changed in the range of more than 0 and 0.167 or less. It is presumed that the wear resistance is improved because the peeling of the interface between the insulating coating layers is suppressed.

(Measurement of imide ring-containing molar ratio to benzene ring present in insulation coating resin)
The imide ring-containing molar ratio with respect to the benzene ring present in the insulating coating resin is determined by the above formula (1), and is theoretically calculated from the molecular structure if the resin composition is known.
On the other hand, when the details of the resin composition are unclear, or for the insulation coating resin layer of the manufactured insulated wire, it can be obtained from the absorbance area of the infrared absorption spectrum measured by a reflection type infrared spectrometer. it can.
Specifically, for example, using a microtome (such as Microtom 2050 SuperCut manufactured by Reichert-Jung), a cross-section of the insulating coating layer is cut out, and a reflective infrared spectroscopic apparatus (manufactured by Thermoscience, Inc.) having an attachment capable of surface analysis. The infrared absorption spectrum of each insulating coating layer is measured with a Nicolet iN10 microinfrared spectrometer, etc.), and from the obtained infrared absorption spectrum, the specific formula of the imide ring relative to the benzene ring is determined by the following formula (2). By obtaining the absorbance area ratio x of the absorption peak and substituting this x into the conversion formula of the following formula (3), the imide ring-containing molar ratio relative to the benzene ring can be obtained.

X = Abs (imidoI) / Abs (BzC = C expansion / contraction) Formula (2)

Here, Abs (imidoI) is an absorbance area of imide ring imidoI (C = O in-plane stretching vibration; absorption peak near 1700-1780 cm ⁻¹ ), and Abs (BzC = C stretching) is the same insulating coating layer. Is the absorbance area of the C = C stretching vibration (absorption peak near 1450-1520 cm ⁻¹ ) of the benzene ring.

Y = cxx xi expression (3)

Here, y is an imide ring-containing molar ratio with respect to the benzene ring, and x is an absorbance area ratio of a specific absorption peak of the imide ring with respect to the benzene ring, obtained by the above formula (2). c represents a constant.

The constant c is obtained from the relationship between y and x in a resin with a known structure.

For example, the infrared absorption spectrum of the resin of the insulating coating layer by Pire-ML (trade name; manufactured by I.S. T.), which is a polyimide resin, is obtained as a chart as shown in FIG. From this chart, the absorbance area (α portion) of the absorption peak 1500 cm ⁻¹ derived from the benzene ring and the absorbance area (β portion) of the absorption peak 1720 cm ⁻¹ derived from the imide ring are determined and substituted into the above formula (2). x = 2.56 is calculated. Since the constant c calculated | required from resin with a known structure is 0.2605, the imide ring containing molar ratio calculated | required from the conversion formula of Formula (3) is 0.667.

The imide ring's imidoI (C = O in-plane stretching vibration) usually has one or two absorptions in the region of 1700 to 1780 cm ^-1 , and the absorbance at the highest wavenumber peak with the highest absorption intensity is calculated. Used for. The C = C stretching vibration, which is the skeleton vibration of the benzene ring, appears as a strong peak in the vicinity of 1450 to 1520 cm ⁻¹ .

In the present invention, the imide ring-containing molar ratio with respect to the benzene ring present in the insulating coating resin may be directly determined by the formula (1) or indirectly by the absorbance area ratio of the infrared absorption spectrum. In the specification, as a representative, hereinafter, it will be described as “determined by the equation (1)”.

The imide ring-containing molar ratio of the innermost insulating coating layer in contact with the aluminum conductor is preferably 0.366 to 0.634, more preferably 0.393 to 0.634, and further preferably 0.400 to 0.634. preferable.
When the imide ring-containing molar ratio of the innermost insulating coating layer in contact with the conductor is 0.366 or more, the adhesiveness with the aluminum conductor is excellent, and when it is less than 0.366, the imide group content is low, Adhesion with the aluminum conductor is deteriorated. If the ratio is 0.634 or less, the adhesion between the aluminum conductors is improved, the adhesion between the insulating coating layers is good, and the wear resistance is excellent.

Also, in the insulating coating layers adjacent to each other, the absolute value of the difference in the imide ring-containing molar ratio of the resins constituting these layers is more than 0 and 0.167 or less between any adjacent insulating coating layers. . The absolute value of the difference in the imide ring-containing molar ratio is preferably 0.026 to 0.167, more preferably 0.030 to 0.167, still more preferably 0.033 to 0.167, and 0.033 to 0. .134 is particularly preferred.
When the absolute value of the difference in the imide ring-containing molar ratio between adjacent insulating coating layers is more than 0 and 0.167 or less, the wear resistance and the insulation after processing are excellent, and when it is 0, the insulation after processing When the ratio is 0.170 or more, the difference in the imide ring-containing molar ratio between adjacent insulating coating layers becomes large, so that the wear resistance is deteriorated.

In the present invention, the absolute value of the difference between the maximum value and the minimum value is preferably more than 0 and 0.300 or less among the imide ring-containing molar ratios obtained for all the insulating coating layers. More preferably, it is 0.300 or less.
By setting the absolute value of the difference between the maximum value and the minimum value to be more than 0 and 0.300 or less, particularly excellent wear resistance can be obtained.

In the present invention, the imide ring-containing molar ratio of the resin constituting the insulating coating layer is the largest in the innermost insulating coating layer in contact with the conductor and the smallest in the outermost insulating coating layer farthest from the conductor. It is particularly preferable that the insulating coating layer becomes smaller in order as it becomes farther from the insulating coating layer closest to the conductor.
In this way, particularly excellent wear resistance can be obtained.

The imide ring-containing molar ratio can be within the range defined by the present invention by changing the number of amide groups, imide groups, and benzene rings present in one resin. It is preferable to adjust by mixing, and in particular, it is preferable to adjust by mixing polyimide resin (PI) and polyamideimide resin (PAI), and in this way, particularly excellent adhesion, Abrasion resistance and stretched BDV are obtained.

(Additive)
In the present invention, the insulating coating layer can contain various additives depending on the purpose.
Examples of such additives include pigments, crosslinking agents, catalysts, and antioxidants.
The content of such an additive is preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the resin constituting the insulating coating layer.

Among the insulating coating layers, the outermost insulating coating layer for coating the conductor of the present invention may be a self-lubricating resin obtained by dispersing and mixing wax or a lubricant by a conventional method. As the wax to be used, commonly used ones can be used without particular limitation, for example, synthetic waxes such as polyethylene wax, petroleum wax, paraffin wax, and natural waxes such as carnauba wax, cadilla wax, and rice wax. Can be mentioned. There is no restriction | limiting in particular also about a lubricant, For example, silicone, a silicone macromonomer, a fluororesin etc. can be used.

<Insulation coated aluminum wire manufacturing method>
The aluminum conductor is adjusted to a predetermined diameter and hardness by performing a wire drawing step and an annealing step. In the wire drawing step, for example, an aluminum conductor having a predetermined diameter can be obtained by drawing a rough drawing wire with a die using a lubricant and repeating the surface reduction process. In the annealing step, for example, annealing is performed for 1 to 100 seconds in a 2 to 8 m furnace set to 300 ° C. to 550 ° C.
Moreover, it is desirable to remove deposits such as oil components and aluminum powder adhering to the surface of the aluminum conductor by a cleaning process using water or an organic solvent.
The method for forming the insulating coating layer on the aluminum conductor may be the same as the generally known method for forming the insulating coating layer on the copper conductor, and a step of applying an insulating coating resin on the aluminum conductor and baking it. By repeating the above, an insulating coating layer composed of two or more layers can be formed.
The specific baking conditions depend on the shape of the furnace used, but for a natural convection type vertical furnace of about 5 m, the passage time is set to 30 to 90 seconds at 400 to 500 ° C. Can be achieved.

(solvent)
The varnish for forming the insulating coating layer can be prepared by dissolving a resin or additive constituting the insulating coating layer in a solvent. Such a solvent is preferably an organic solvent, for example, an amide solvent such as N-methyl-2-pyrrolidone (NMP), N, N-dimethylacetamide (DMAC), dimethyl sulfoxide, N, N-dimethylformamide, Urea solvents such as N, N-dimethylethyleneurea, N, N-dimethylpropyleneurea, tetramethylurea, lactone solvents such as γ-butyrolactone and γ-caprolactone, carbonate solvents such as propylene carbonate, methyl ethyl ketone, methyl isobutyl Ketone solvents such as ketone, cyclohexanone, ester solvents such as ethyl acetate, n-butyl acetate, butyl cellosolve acetate, butyl carbitol acetate, ethyl cellosolve acetate, ethyl carbitol acetate, diglyme, triglyme, Examples include glyme solvents such as tetraglyme, hydrocarbon solvents such as toluene, xylene, and cyclohexane, and sulfone solvents such as sulfolane. Of these, amide solvents and urea solvents are preferable in view of high solubility, high reaction acceleration, and the like, and N-methyl-2 is preferable in that it does not have a hydrogen atom that easily inhibits a crosslinking reaction by heating. -Pyrrolidone, N, N-dimethylacetamide, N, N-dimethylethyleneurea, N, N-dimethylpropyleneurea and tetramethylurea are more preferred, and N-methyl-2-pyrrolidone is particularly preferred. The boiling point of the organic solvent is preferably 160 ° C. to 250 ° C., more preferably 165 ° C. to 210 ° C.

<Performance of insulated aluminum wire>
The insulation-coated aluminum electric wire of the present invention is excellent in adhesion to an aluminum conductor, adhesion between insulation-coated resin layers, wear resistance, and insulation.
These performances can be evaluated by the values measured as follows.

(Adhesion with conductor)
According to the adhesion test method of JIS C3003-1984, for example, an autograph AGS-J (manufactured by Shimadzu Corporation) is used as a measuring instrument, and the aluminum conductor is stretched until it breaks. Measure the floating length of the insulation film.
In the present invention, the floating length is preferably less than 20 mm, and more preferably less than 2 mm. Since the floating length is measured visually using a measurement gauge, the practical lower limit is 0.1 mm or more.

(Abrasion resistance)
A unidirectional wear test is performed using a scrape tester (wire electric wire wear tester for automobiles), for example, NEMA scrape tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.), and evaluation is performed by the wear resistance test method of JIS C3003-1984.
In the present invention, the insulated wire was stretched 10% under the conditions of a temperature of 20 ± 10 ° C. and a relative humidity of 65 ± 15%, attached to a measuring instrument in a straight state, and the load until the insulation coating layer was broken was measured. The value is preferably 1400 g or more, and more preferably 1500 g or more. In the case of an insulating coated aluminum electric wire with a circular conductor having a total thickness of 30 μm and a diameter of 1 mm as in the present embodiment, the practical upper limit is 3520 g or less.

(Insulation after processing)
Using a tabletop precision universal testing machine (for example, Autograph AGS-J, manufactured by Shimadzu Corporation), a test piece obtained by extending an insulated wire by 10% was subjected to a dielectric breakdown test method of JIS C3003-1984. Measure the breakdown voltage (BDV) using a breakdown voltage measuring instrument. The greater the value, the better the insulation after processing.
In this invention, Preferably it is 8 kV or more, More preferably, it is 10 kV or more. In the case of an insulation coated aluminum electric wire having a total thickness of 30 μm and a diameter of 1 mm, as in the present embodiment, the practical upper limit value is 25 kV or less.

<Application of insulated aluminum wire>
Since the insulation-coated aluminum electric wire of the present invention is lightweight and can be reduced in size, it can be used for coils of motors and generators. Specifically, it can be preferably used for a winding for a drive motor of, for example, a hybrid vehicle (HV) or an electric vehicle (EV) where a high product ratio is required.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

The materials used for the resin composition are the following materials.
(A) Polyamideimide resin HI406 (trade name; manufactured by Hitachi Chemical Co., Ltd.): molar ratio of the imide ring to the benzene ring in the state where the coating layer is formed 1 / 3≈0.333
(B) Polyimide resin Pyre-ML (trade name; manufactured by IST): Imide ring-containing molar ratio of resin to benzene ring in a state where a coating layer is formed 2 / 3≈0.667
(C) Polyetherimide resin ULTEM 1010 (trade name; manufactured by Solvay): molar ratio of imide ring to resin benzene ring in a state where a coating layer is formed is 0.400.
(D) Polyethersulfone resin Sumika Excel 4800G (trade name; manufactured by Sumitomo Chemical Co., Ltd.): Imide ring-containing molar ratio of resin to benzene ring in a state where a coating layer is formed 0.0

(Production of varnish)
-Production of Varnish 1 Polyamideimide resin (A) and polyimide resin (B) were mixed and stirred so that the solid content ratios were 90% and 10%, respectively, and varnish 1 was produced.

-Preparation of varnishes 2-10, varnish 12, varnish A, and varnish B As with varnish 1, varnishes 2-9 are polyamideimide resin (A) and polyimide resin so that the solid content ratios shown in Table 1 below are obtained. (B), varnish 10 is polyamideimide resin (A) and polyetherimide resin (C), varnish 12 is polyamideimide resin (A) and polyethersulfone resin (D) mixed and stirred, and varnish 2 to 10 and 12 were produced. Varnish A had a solid content of 100% polyimide resin (B), and Pire-ML (manufactured by IST Co.) was used as it was. Varnish B had a solid content of 100% polyamideimide resin (A), and HI406 (manufactured by Hitachi Chemical Co., Ltd.) was used as it was.

-Production of Varnish 11 A three-necked flask with a capacity of 4 liters was prepared with a synthesis apparatus equipped with a heating / cooling device, a nitrogen introducing device, and a stirrer. Among them, trimellitic anhydride (TMA) 172.9 g (0.9 mol), pyromellitic dianhydride (PMDA) 21.8 g (0.1 mol), diphenylmethane-4,4′-diisocyanate ( MDI) 250.1 g (1.0 mol) and 851.2 g of N-methyl-2-pyrrolidone as a solvent were added, and the temperature was raised from room temperature to 140 ° C. over 2 hours while stirring in a nitrogen stream. Stirring was continued at 140 ° C. for 2 hours until carbon dioxide gas was vigorously generated from the flask and the solution in the flask became viscous. Thereafter, it was cooled to room temperature to obtain 1216 g of varnish 11 (resin concentration: 30% by mass).

Along with the resin components of varnishes 1 to 12 and varnishes A and B produced above, each varnish is a circular conductor of aluminum (diameter R = 1.0 mm) having an aluminum purity of 99.9% or more, and the shape of the conductor is similar. The imide ring-containing moles of the entire resin of the resin layer formed by baking a plurality of times in a baking furnace with a furnace length of 8 m under a baking temperature of 450 ° C. and a baking time of approximately 15 seconds. The ratios are summarized in Table 1 below.

Example 1
Varnish 6 (layer 1) having a molar ratio of imide ring to benzene ring of 0.533 is formed on a circular conductor of aluminum (diameter R = 1.0 mm) having an aluminum purity of 99.9% or more from the aluminum conductor side. Varnish 4 (layer 2) having a thickness of 3 μm and an imide ring-containing molar ratio to the benzene ring of 0.467 is formed as a film of varnish 2 (layer 3) having a film thickness of 3 μm and an imide ring-containing molar ratio to the benzene ring of 0.400. Insulation wire having a thickness of 3 μm and an insulating coating layer of varnish B (layer 4) having a imide ring-containing molar ratio of 0.333 to a benzene ring in the order of a film thickness of 21 μm and an overall insulating coating layer thickness of 30 μm Was made.
The difference between the imide ring-containing molar ratio of the innermost layer 1 to the benzene ring and the difference in the imide ring-containing molar ratio to the benzene ring in all adjacent layers, and the maximum value of the imide ring-containing molar ratio to the benzene ring in all insulating coating layers The absolute value of the difference between the minimum values is shown in Table 2 below.
In addition, when forming the insulating coating layer, a plurality of dies having a shape similar to the shape of the conductor are used, and baking is performed a plurality of times in a baking furnace having a furnace length of 8 m under a baking temperature of 450 ° C. and a baking time of approximately 15 seconds. went.

Examples 2 to 12 and Comparative Examples 1 to 5
Insulated wires of Examples 2 to 12 and Comparative Examples 1 to 5 were prepared in the same manner as Example 1 except that the varnish types and film thicknesses described in Tables 2 and 3 below were changed as shown in the layer structure. did.

Comparative Example 6
A copper circular conductor having an oxygen content of 15 ppm was used in place of the aluminum circular conductor, and the same as in Example 1 except that the type and film thickness of the varnish described in Table 3 below and the layer configuration were changed. Thus, an insulated wire of Comparative Example 6 was produced.

The following evaluation was performed on each of the above insulated wires.

(Calculation of the molar ratio of imide ring to benzene ring in the resin by infrared absorption spectrum)
The cross section of the insulating coating layer is cut out for each of the insulated wires produced above using a microtome (Microtome 2050 SuperCut manufactured by Reichert-Jung). Measure the infrared absorption spectrum of the cross section of the resin of each insulation coating layer using a reflective infrared spectrometer (Nicolet iN10 microinfrared spectrometer manufactured by Thermoscience) equipped with an attachment capable of surface analysis did.
The absorbance area ratio x of the specific absorption peak of the imide ring to the benzene ring obtained from the infrared absorption spectrum is obtained from the following formula (2), and the molar ratio of the imide ring to the benzene ring in the resin is calculated from the following conversion formula (3). Was calculated.
x = Abs (imidoI) / Abs (BzC = C expansion / contraction) Formula (2)

Abs (imido I) is an absorbance area of imide ring imido I (C = O in-plane stretching vibration; absorption peak near 1700-1780 cm ⁻¹ ), and Abs (BzC = C stretching) is benzene in the same insulating coating layer. Absorbance area of ring C = C stretching vibration (absorption peak near 1450-1520 cm ⁻¹ ).

Y = cxx expression (3)

The above y is an imide ring-containing molar ratio with respect to the benzene ring, and x is an absorbance area ratio of a specific absorption peak of the imide ring with respect to the benzene ring, which is obtained by the above formula (2). c represents a constant.

FIG. 2 shows a chart of the infrared absorption spectrum of the resin of the insulating coating layer formed of Pire-ML (trade name; manufactured by IST Co.) which is a polyimide resin. From the absorbance area (α part) of the absorption peak 1500 cm ⁻¹ derived from the benzene ring and the absorbance area (β part) of the absorption peak 1720 cm ⁻¹ derived from the imide ring, x was 2.56. The constant c in the formula (3) is 0.2605 from the relationship between the imide ring-containing molar ratio with respect to the benzene ring obtained from a resin having a known structure and the absorbance area ratio of a specific absorption peak of the imide ring with respect to the benzene ring. When x = 2.56 was substituted into the above formula (3), the imide ring-containing molar ratio was 0.667.

In the case of HI406 (trade name; manufactured by Hitachi Chemical Co., Ltd.) which is a polyamide-imide resin, x is 1.28, and in the case of a resin of an insulating coating layer formed of varnish 5, x is 1.92. From the formula (3), the imide ring-containing molar ratios were 0.333 and 0.500, respectively.
Similarly, the imide ring-containing molar ratio of the resin of the insulating coating layer formed from another varnish was determined.

(Adhesion evaluation)
In accordance with the adhesion test method of JIS C3003-1984, an autograph AGS-J (manufactured by Shimadzu Corporation) is used as a measuring instrument, and the aluminum conductor is stretched until it breaks. The floating length was measured, and those with a length of less than 2 mm were evaluated as ◎, those with a diameter of 2 mm or more but less than 20 mm were evaluated as ◯, those with a diameter of 20 mm or more but less than 100 mm were evaluated as Δ, and those with a diameter of 100 mm or more as x.

(Abrasion resistance evaluation)
Evaluation was carried out as follows by the wear resistance test method of JIS C3003-1984.
A NEMA scrape tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.) was used for the unidirectional wear test, and the insulated wire was stretched 10% and straightened at a temperature of 20 ± 10 ° C and a relative humidity of 65 ± 15%. The load until the insulating coating layer was broken was measured while attached to the measuring instrument. The higher the value, the better the wear resistance. 1500 g or more was evaluated as ◎, 1400 g or more and less than 1500 g was evaluated as ◯, 1300 g or more and less than 1400 g as Δ, and less than 1300 g as x.

[Evaluation of insulation after processing: Dielectric breakdown voltage after elongation (BDV)]
Using a desktop precision universal testing machine (manufactured by Shimadzu Corp., Autograph AGS-J), a test piece obtained by extending an insulated wire by 10% was subjected to a dielectric breakdown test method of JIS C3003-1984. A dielectric breakdown voltage measuring instrument was used as a measuring instrument, and a dielectric breakdown voltage (BDV) was measured. The greater the value, the better the insulation after processing. A value of 10 kV or more was evaluated as ◎, a value of 8 kV or more and less than 10 kV was evaluated as ◯, a value of 5 kV or more and less than 8 kV was evaluated as Δ, and a value of less than 5 kV was evaluated as ×.

In all evaluations, the target level is ○ or higher.
The obtained results are summarized in Tables 2 and 3 below.
Here, the imide ring-containing molar ratio is abbreviated as imide ring-containing ratio in the table.

As is apparent from Tables 2 and 3 above, the multilayer insulated wires of Examples 1 to 12 are all excellent in adhesion, dielectric breakdown voltage (BDV) after extension, and wear resistance. The single-layer insulation-coated wires of Examples 1 to 3 and the multilayer insulation-coated wires of Comparative Examples 4 to 6 had insufficient adhesion, BDV after elongation, or wear. In Comparative Example 1 in which the imide ring-containing molar ratio of the innermost insulating coating layer was less than 0.366, adhesion was particularly poor. In addition, the absolute value of the difference in the imide ring-containing molar ratio of the insulating coating layers adjacent to each other is in the range of 0 to 0.167 or less, and Comparative Examples 4 and 5, which are single-layer insulating coated electric wires. No. 3 did not satisfy the BDV and wear resistance after elongation. In Comparative Example 4, not only the absolute value of the difference in the imide ring-containing molar ratio of the insulating coating layers adjacent to each other exceeds 0 and is outside the range of 0.167, but also the imide ring of the innermost insulating coating layer. The content molar ratio is larger than the preferred range, and the absolute value of the difference between the maximum value and the minimum value of the imide ring-containing molar ratio exceeds the preferred range among all the insulating coating layers, so the wear resistance is deteriorated. I think that the.
In Comparative Example 6, which is the same as the insulating coating layer configuration described in the example of Prior Art Document 1, the adhesion ratio was poor because the imide ring-containing molar ratio of the innermost insulating coating layer was less than 0.366.

While this invention has been described in conjunction with its embodiments, we do not intend to limit our invention in any detail of the description unless otherwise specified and are contrary to the spirit and scope of the invention as set forth in the appended claims. I think it should be interpreted widely.

This application claims priority based on Japanese Patent Application No. 2014-144600 filed in Japan on July 14, 2014, the contents of which are incorporated herein by reference. Capture as part.

1 Aluminum conductor 10 Insulating layer (first layer: innermost layer)
11 Insulating layer (second layer)
12 Insulating layer (third layer)
13 Insulating layer (4th layer)
14 Insulating layer (5th layer)
20 Insulating layer (6th layer: outermost layer)
Absorption area of absorption peak 1500 cm ⁻¹ derived from α-benzene ring Absorbance area of absorption peak 1720 cm ⁻¹ derived from β-imide ring

Claims

An insulating coated aluminum electric wire having an insulating coating layer containing a resin having at least a benzene ring and an imide ring on the outer periphery of a conductor, and having two or more insulating coating layers coated thereon, Resin constituting the inner insulating coating layer having a molar ratio of imide ring to benzene ring determined by the following formula (1) of 0.366 or more and constituting the insulating coating layer adjacent to each other. An insulation-coated aluminum electric wire characterized in that the absolute value of the difference in the imide ring-containing molar ratio is more than 0 and 0.167 or less between any adjacent insulation coating layers.
Total number of moles of imide ring in resin / total number of moles of benzene ring Formula (1)
The insulation-coated aluminum electric wire according to claim 1, wherein an absolute value of the difference in the molar ratio of the imide ring is 0.033 or more and 0.167 or less.
The insulating coating aluminum according to claim 1 or 2, wherein the molar ratio of the imide ring contained in the resin constituting the innermost insulating coating layer in contact with the conductor is 0.366 to 0.634. Electrical wire.
4. The absolute value of the difference between the maximum value and the minimum value of the imide ring-containing molar ratio among all the insulating coating layers is 0 to 0.30 or less. The insulation-coated aluminum electric wire according to item 1.
The absolute value of the difference between the maximum value and the minimum value of the imide ring-containing molar ratio in all of the insulating coating layers is 0.033 or more and 0.300 or less. The insulation-coated aluminum electric wire according to claim 1.
The imide ring-containing molar ratio of the resin constituting the insulating coating layer is the largest in the innermost insulating coating layer in contact with the conductor and the smallest in the outermost insulating coating layer farthest from the conductor. The insulation-coated aluminum electric wire according to any one of claims 1 to 5.
Of the two or more insulating coating layers, the thickness of the innermost insulating coating layer in contact with the conductor is the same as or thinner than the thickness of any of the remaining insulating coating layers. The insulation-coated aluminum electric wire according to any one of claims 1 to 6.
The insulation-coated aluminum electric wire according to any one of claims 1 to 7, wherein a thickness of at least one of the two or more insulation coating layers is more than 0 µm and 25 µm or less.
The insulation-coated aluminum electric wire according to any one of claims 1 to 8, wherein the resin contained in the insulation coating layer is a mixture of a polyamide-imide resin and a polyimide resin.