Insulated wire and resin composition

Abstract

An insulated wire provided with a conductor and a coating film covering the conductor, the coating film including: an adhesion layer in contact with the conductor; and an insulating layer formed on the adhesion layer, the adhesion layer containing a nitrogen-containing organic compound and a first resin, the insulating layer containing a second resin, the first resin and the second resin being one or more resins selected from the group consisting of polyimides and polyamideimides, the ratio of the total atomic weight of nitrogen atoms constituting the nitrogen-containing organic compound to the molecular weight of the nitrogen-containing organic compound is 60% or more.

Description

Technical Field

[0001] The present disclosure relates to an insulated wire and a resin composition. Background Art

[0002] Conventionally, in motors, transformers, etc., an electronic device (such as an insulated wire) having a conductor and a film covering the conductor has been used (Patent Document 1, Patent Document 2). Further, conventionally, a resin composition containing an adhesion additive and a resin has been used in an electronic device (Patent Document 3).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: International Publication No. 2019 / 138971

[0006] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2002-321310

[0007] Patent Document 3: Japanese Unexamined Patent Application Publication No. 2019-168698 Summary of the Invention

[0008] The insulated wire of the present disclosure is an insulated wire having a conductor and a film covering the conductor, the film including: an adhesion layer in contact with the conductor; and an insulating layer formed on the adhesion layer, the adhesion layer including a nitrogen-containing organic compound and a first resin, the insulating layer including a second resin, the first resin and the second resin each being one or more selected from the group consisting of polyimide and polyamideimide, and the ratio of the total atomic weight of the nitrogen atoms constituting the nitrogen-containing organic compound to the molecular weight of the nitrogen-containing organic compound being 60% or more. Brief Description of the Drawings

[0009] Figure 1 It is a schematic cross-sectional (transverse cross-section) view exemplifying one embodiment of the insulated wire of the present disclosure. Detailed Description

[0010] [Problems to be Solved by the Present Disclosure]

[0011] For the insulated wire as described above, high adhesion between the conductor and the film is required. In the manufacture of the insulated wire, the adhesion between the conductor and the film is improved by a chemical reaction between the conductor and an adhesion additive. Further, this chemical reaction requires a certain amount of heat. On the other hand, in recent years, for the purpose of increasing the production rate of the insulated wire, high line speed in the manufacture of the insulated wire has been required. Therefore, along with this high line speed, the heat required for this chemical reaction is insufficient, and thus the adhesion between the conductor and the film is sometimes insufficient. Therefore, there is a demand for an insulated wire having excellent adhesion between the conductor and the film even when manufactured under the manufacturing conditions of an insulated wire with high line speed.

[0012] Accordingly, an object of the present disclosure is to provide an insulated wire having excellent adhesion between a conductor and a film even when manufactured under the manufacturing conditions of an insulated wire with a high wire speed.

[0013] [Effects of the Present Disclosure]

[0014] According to the present disclosure, an insulated wire having excellent adhesion between a conductor and a film even when manufactured under the manufacturing conditions of an insulated wire with a high wire speed can be provided.

[0015] [Description of Embodiments of the Present Disclosure]

[0016] First, embodiments of the present disclosure will be listed and described.

[0017] (1) The insulated wire of the present disclosure is an insulated wire including a conductor and a film covering the conductor, the film including: an adhesion layer in contact with the conductor; and an insulating layer formed on the adhesion layer, the adhesion layer including a nitrogen-containing organic compound and a first resin, the insulating layer including a second resin, the first resin and the second resin being each one or more selected from the group consisting of polyimide and polyamideimide, and the proportion of the total atomic weight of nitrogen atoms constituting the nitrogen-containing organic compound relative to the molecular weight of the nitrogen-containing organic compound being 60% or more.

[0018] According to the present disclosure, an insulated wire having even more excellent adhesion between a conductor and a film even when manufactured under the manufacturing conditions of an insulated wire with a high wire speed can be provided.

[0019] (2) Preferably, in the above (1), the content of the nitrogen-containing organic compound is 0.010% by mass or more and 5.0% by mass or less relative to the adhesion layer. Thereby, an insulated wire having even more excellent adhesion between a conductor and a film even when manufactured under the manufacturing conditions of an insulated wire with a high wire speed can be provided.

[0020] (3) Preferably, in the above (1) or (2), the nitrogen-containing organic compound does not have a 1,3,5-triazine ring structure. Thereby, an insulated wire having even more excellent adhesion between a conductor and a film even when manufactured under the manufacturing conditions of an insulated wire with a high wire speed can be provided.

[0021] (4) Preferably, in any one of the above (1) to (3), the polyimide is a polymer of a tetracarboxylic dianhydride and a diamine compound. The tetracarboxylic dianhydride is either or both of pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride, and the diamine compound is 4,4'-diaminodiphenyl ether. Thus, an insulated wire having more excellent adhesion between the conductor and the film can be provided even when manufactured under the manufacturing conditions of an insulated wire with a high linear velocity.

[0022] (5) Preferably, in any one of the above (1) to (4), the polyamideimide is a polymer of a tricarboxylic anhydride and a diisocyanate compound. The tricarboxylic anhydride is trimellitic anhydride, and the diisocyanate compound is diphenylmethane diisocyanate. Thus, an insulated wire having more excellent adhesion between the conductor and the film can be provided even when manufactured under the manufacturing conditions of an insulated wire with a high linear velocity.

[0023] (6) The resin composition of the present disclosure is a resin composition for an adhesion layer of an insulated wire. The resin composition contains a nitrogen-containing organic compound, a solvent, and one or more selected from the group consisting of polyamic acid and polyamideimide. The ratio of the total atomic weight of the nitrogen atoms constituting the nitrogen-containing organic compound to the molecular weight of the nitrogen-containing organic compound is 60% or more.

[0024] According to the resin composition of the present disclosure, an insulated wire having excellent adhesion between the conductor and the film can be provided even when manufactured under the manufacturing conditions of an insulated wire with a high linear velocity.

[0025] [Details of the Embodiment of the Present Disclosure]

[0026] Hereinafter, a specific example of an insulated wire according to an embodiment of the present disclosure (hereinafter also referred to as "this embodiment") will be described with reference to the drawings. In the drawings of the present disclosure, the same reference numerals denote the same or corresponding parts. In addition, the dimensional relationships such as length, width, thickness, depth, etc. are appropriately changed for the clarity and simplification of the drawings and do not necessarily represent the actual dimensional relationships.

[0027] In this specification, the expression in the form of "A to B" means the upper and lower limits of the range (that is, A or more and B or less). When no unit is described for A and only a unit is described for B, the unit of A is the same as the unit of B.

[0028] [Embodiment 1: Insulated Wire]

[0029] Use Figure 1 An insulated wire according to an embodiment of the present disclosure will be described.

[0030] One embodiment of the present disclosure (hereinafter also referred to as "this embodiment") is an insulated wire 1 having a conductor 11 and a coating 12 covering the conductor 11. The coating 12 includes: an adhesion layer 13 in contact with the conductor 11; and an insulating layer 14 formed on the adhesion layer 13. The adhesion layer 13 includes a nitrogen-containing organic compound and a first resin, the insulating layer 14 includes a second resin, the first resin and the second resin are each one or more selected from the group consisting of polyimide and polyamideimide, and the proportion of the total atomic weight of the nitrogen atoms constituting the nitrogen-containing organic compound relative to the molecular weight of the nitrogen-containing organic compound is 60% or more.

[0031] According to the present disclosure, it is possible to provide an insulated wire having excellent adhesion between the conductor and the coating even when manufactured under the manufacturing conditions of an insulated wire with a high linear velocity. The reason is presumably as follows.

[0032] Through the ionic bonding reaction between the conductor 11 (cation) and the adhesion additive (anion), the adhesion between the conductor 11 and the adhesion layer 13 is improved. In addition, this ionic bonding reaction requires a certain amount of heat. However, when manufacturing the insulated wire 1 under the manufacturing conditions of the insulated wire 1 with a high linear velocity, there is a tendency that the heat required for this ionic bonding reaction is insufficient. In the insulated wire 1 of the present disclosure, the coating 12 includes: an adhesion layer 13 in contact with the conductor 11; and an insulating layer 14 formed on the adhesion layer 13. The adhesion layer 13 includes a nitrogen-containing organic compound and a first resin, and the proportion of the total atomic weight of the nitrogen atoms constituting the nitrogen-containing organic compound relative to the molecular weight of the nitrogen-containing organic compound is 60% or more. Thus, the stability of the nitrogen-containing organic compound when bonding to the metal constituting the conductor 11 is excellent, so that even with low heat, the ionic bonding reaction between the conductor 11 and the adhesion additive (the nitrogen-containing organic compound) can proceed. Therefore, the insulated wire 1 having the coating 12 including such an adhesion layer 13 can have excellent adhesion between the conductor 11 and the coating 12 even when manufactured under the manufacturing conditions of the insulated wire 1 with a high linear velocity.

[0033] 《Structure of Insulated Wire》

[0034] The shape of the insulated wire 1 of this embodiment is a linear body. The shape of the cross-section of the insulated wire 1 can be circular (including substantially circular), elliptical, or flat. Here, the cross-section of the insulated wire 1 refers to the cross-section that appears when the insulated wire 1 is cut by a plane perpendicular to the long dimension direction. Among "flat", which is one of the shapes of the cross-section of the insulated wire 1, rectangles and squares are included, and shapes in which the four corners of the rectangle and the square are chamfered or have an arc shape (R shape) are included.

[0035] In addition, here, preferably, the "coated conductor 11" refers to the entire surface of the coated conductor 11, but as long as the effects of the present disclosure are exhibited, even if a part of the surface of the conductor 11 is not coated with the coating 12, it does not deviate from the scope of the present disclosure.

[0036] 《Conductor》

[0037] The insulated wire 1 of the present embodiment includes a conductor 11 ( Figure 1 ). The conductor 11 refers to a conductive body. As the material of the conductor 11, a metal with high conductivity and high mechanical strength is preferred. Specifically, copper, copper alloy, aluminum, aluminum alloy, nickel, silver, soft iron, steel, stainless steel, etc. can be cited. The conductor can be a wire formed by shaping these metals into a linear shape, a coated wire obtained by coating the surface of a wire with another metal, or a stranded wire formed by stranding a plurality of wires. As the coated wire, nickel-coated copper wire, silver-coated copper wire, silver-coated aluminum wire, copper-coated steel wire, etc. can be cited, but it is not limited thereto.

[0038] The shape of the conductor 11 is not particularly limited, and a round wire, a square wire, etc. can be appropriately selected according to the use purpose, electrical characteristics, etc. of the insulated wire 1. That is, the cross-sectional shape of the conductor 11 can be circular (including substantially circular) or flat. Here, the cross-section of the conductor 11 refers to the cross-section obtained by cutting the conductor with a plane perpendicular to the long dimension direction. In addition, the diameter or the outer peripheral length of the conductor 11 is not particularly limited, and can be appropriately selected according to the use purpose, electrical characteristics, etc. of the insulated wire.

[0039] 《Coating》

[0040] <Structure of the coating>

[0041] The insulated wire 1 of the present embodiment includes a coating 12 that coats the conductor 11 ( Figure 1 ). The thickness of the coating 12 is preferably 5 μm or more and 500 μm or less. When the thickness of the coating 12 does not reach 5 μm or more, the coating 12 tends to be easily damaged, and the insulation of the coating 12 may become insufficient. When the thickness of the coating 12 exceeds 500 μm or less, the volume efficiency of a coil or the like formed by using the insulated wire 1 tends to be low.

[0042] The thickness of the coating 12 refers to the average value of the thickness of the coating 12 in the cross-section of the insulated wire 1. Hereinafter, it will be described in further detail including its measurement method. Specifically, first, microscopic images of any five cross-sections of the insulated wire are obtained by a scanning electron microscope (SEM). Next, any five points are selected on the outer periphery (the outermost surface) of the insulated wire 1 in each of the above microscopic images, and the shortest distance from the outer periphery to the conductor 11 is obtained at each point, and this shortest distance is taken as the thickness of the coating 12. The average value can be calculated based on the values obtained by measuring the thickness of the coating 12 at a total of 25 locations, and this average value is taken as the thickness of the coating 12. It should be noted that in the above measurement, in the case where there are obvious outliers, the outliers are excluded to calculate the average value. In the case where there are three or more outliers, as an alternative, the same number of measurements are further performed, and the average value is calculated using the values obtained therefrom.

[0043] It was confirmed that as long as the measurement is performed on the same insulated wire 1, there is no deviation in the measurement results even if the measurement site is arbitrarily selected.

[0044] 《Adhesive layer》

[0045] <Composition of the adhesive layer>

[0046] The coating 12 includes an adhesive layer 13 that is in contact with the conductor 11 ( Figure 1 ). The adhesive layer 13 includes a nitrogen-containing organic compound and a first resin. Here, "including a nitrogen-containing organic compound and a first resin" means that the adhesive layer 13 may be composed of the nitrogen-containing organic compound and the first resin, or the adhesive layer 13 may further include, for example, fillers, curing agents, other additives, "resins other than the first resin", etc. as components other than the nitrogen-containing organic compound and the first resin.

[0047] (Nitrogen-containing organic compound)

[0048] The ratio of the total atomic weight of the nitrogen atoms constituting the nitrogen-containing organic compound to the molecular weight of the nitrogen-containing organic compound is 60% or more. Thereby, even with low heat, the ionic bonding reaction between the conductor 11 and the adhesion additive (the nitrogen-containing organic compound) can proceed, so that excellent adhesion between the conductor 11 and the coating 12 can be achieved even in the case of manufacturing the insulated wire 1 under high wire speed conditions. The lower limit of this ratio is preferably 61% or more, more preferably 65% or more, and further preferably 70% or more. The upper limit of this ratio is preferably 83% or less, more preferably 82% or less, and further preferably 81% or less. This ratio is preferably 61% or more and 83% or less, more preferably 70% or more and 82% or less, and further preferably 70% or more and 81% or less.

[0049] It should be noted that for the sealing layer 13, this ratio can be determined by the following method. That is, first, obtain an arbitrary cross-section of the insulated wire. Then, by performing analysis such as TOF-SIMS on the region of the sealing layer in this cross-section, identify the structure of the nitrogen-containing organic compound, determine the molecular weight of the nitrogen-containing organic compound, and the number of nitrogen atoms in one molecule of the nitrogen-containing organic compound. Then, multiply the value obtained by dividing the product of the number of nitrogen atoms and the atomic weight of nitrogen "14.01" by the molecular weight of the nitrogen-containing organic compound by 100, thereby obtaining this ratio. It should be noted that it is confirmed that as long as the measurement is performed on the same insulated wire, even if the measurement site is arbitrarily selected, there is no deviation in the measurement result.

[0050] Preferably, the nitrogen-containing organic compound does not have a 1,3,5-triazine ring structure. Thereby, inactivation caused by self-assembly of compounds derived from the triazine ring structure can be prevented, and thus an insulated wire 1 with more excellent adhesion between the conductor 11 and the coating 12 can be provided even under the manufacturing conditions of the insulated wire 1 with high wire speed.

[0051] In the sealing layer 13, whether the nitrogen-containing organic compound does not have a 1,3,5-triazine ring structure can be determined by the following method. That is, first, obtain an arbitrary cross-section of the insulated wire. Then, by performing analysis such as TOF-SIMS on the region of the sealing layer in this cross-section, identify the structure of the nitrogen-containing organic compound and determine whether there is a triazine ring structure in the nitrogen-containing organic compound. It should be noted that it is confirmed that as long as the measurement is performed on the same insulated wire, even if the measurement site is arbitrarily selected, there is no deviation in the measurement result.

[0052] Preferably, the nitrogen-containing organic compound does not contain sulfur elements. Thereby, corrosion of the conductor metal caused by sulfur elements can be prevented, and thus an insulated wire 1 with more excellent adhesion between the conductor 11 and the coating 12 can be provided even under the manufacturing conditions of the insulated wire 1 with high wire speed.

[0053] In the sealing layer 13, whether the nitrogen-containing organic compound does not contain sulfur elements can be determined by the following method. That is, first, obtain an arbitrary cross-section of the insulated wire. Then, by performing analysis such as TOF-SIMS on the region of the sealing layer in this cross-section, identify the structure of the nitrogen-containing organic compound and determine whether there is sulfur element in the nitrogen-containing organic compound. It should be noted that it is confirmed that as long as the measurement is performed on the same insulated wire, even if the measurement site is arbitrarily selected, there is no deviation in the measurement result.

[0054] As the nitrogen-containing organic compound, specifically, for example, 5-aminotetrazole, tetrazole, aminoguanidine, 3,5-diamino-1,2,4-triazole, dicyandiamide, 3-amino-1,2,4-triazole, melamine, 1,2,4-triazole, etc. can be cited. As the nitrogen-containing organic compound, from the aspect of not having a 1,3,5-triazine ring structure, at least one nitrogen-containing organic compound selected from the group consisting of 5-aminotetrazole, tetrazole, aminoguanidine, diamino-triazole, dicyandiamide, and amino-triazole is particularly preferred.

[0055] The content of the nitrogen-containing organic compound is preferably 0.010% by mass or more and 5.0% by mass or less with respect to the adhesion layer 13. Thus, near the interface of the conductor 11, it is easy to ensure a sufficient content of the nitrogen-containing organic compound for the adhesion between the conductor 11 and the adhesion layer 13. Therefore, even when manufactured under the manufacturing conditions of an insulated wire with a high linear velocity, better adhesion can be achieved between the conductor 11 and the film 12. The lower limit of the content of the nitrogen-containing organic compound is preferably 0.010% by mass or more, more preferably 0.05% by mass or more, and further preferably 0.10% by mass or more with respect to the adhesion layer 13. The upper limit of the content of the nitrogen-containing organic compound is preferably 5.0% by mass or less, more preferably 4.5% by mass or less, and further preferably 4.0% by mass or less with respect to the adhesion layer 13. In addition, the content of the above-mentioned nitrogen-containing organic compound is more preferably 0.05% by mass or more and 4.5% by mass or less, and further preferably 0.10% by mass or more and 4.0% by mass or less with respect to the adhesion layer 13.

[0056] Note that in the sealing layer 13, the content of the nitrogen-containing organic compound can be determined by the following method. First, a part of the sealing layer 13 is extracted from the coating 12 of the insulated wire 1. Next, the mass of this part is measured. Next, this part is cryogenically pulverized to obtain a sample. Next, the sample is added to the solvent described below and shaken at room temperature for 24 hours to obtain the shaken sample and the extract. Next, the extract is filtered to obtain a filtrate. Next, under the following conditions, LC / MS (Liquid Chromatography-Mass Spectrometry) measurement is performed on the filtrate to measure the extraction amount of the nitrogen-containing organic compound. Note that as the solvent, dimethylformamide, tetrahydrofuran, methanol, and water can be used respectively, and the ratio of the highest extraction amount calculated as a percentage to the mass of this part is used to obtain the content of the nitrogen-containing organic compound. In the case where it is difficult to extract a part of the sealing layer 13 from the coating 12 of the insulated wire 1, it can be obtained by the following method. First, a part of the coating 12 is extracted from the insulated wire 1. Next, the mass of this part is measured. Next, this part is cryogenically pulverized to obtain a sample. Except for this, by the same method as above, the extraction amount of the nitrogen-containing organic compound in the part of the coating 12 is measured. In addition, for the mass ratio of the sealing layer 13 to the coating 12, the cross-section of the insulated wire 1 is observed by SEM, and the proportion of the area of the sealing layer 13 in the area of this cross-section is calculated using image processing software ("Winroof" manufactured by Mitani Corporation) to obtain the area ratio as the mass ratio. Next, the mass of the sealing layer 13 in this part is obtained by multiplying the mass of this part by this ratio. Next, the content of the nitrogen-containing organic compound in the part of the sealing layer 13 can be obtained by calculating the ratio of the extraction amount of the nitrogen-containing organic compound in this part to the mass of the sealing layer 13 as a percentage.

[0057] (LC / MS measurement conditions)

[0058] Analysis device: Thermo Fisher Scientific, UltiMate3000 / TSQ Quantum AccessMAX

[0059] Column: L-column3 C8 (4.6mmφ×150mm, 5μm)

[0060] Eluent composition: water / methanol system gradient

[0061] Flow rate: 1.0mL / min

[0062] Detector: MS(SRM), DAD (190nm - 400nm, extraction at 220nm)

[0063] Column temperature: 40°C

[0064] Injection volume: 5 μL

[0065] Ionization method: ESI(POS.)

[0066] Ionization voltage: 3 kV

[0067] Evaporation temperature: 400°C

[0068] Capillary temperature: 280°C

[0069] It was confirmed that: as long as the measurement is carried out using the same insulating wire 1, even if the measurement part is arbitrarily selected, there is no deviation in the measurement result.

[0070] (First resin)

[0071] The first resin is one or more selected from the group consisting of polyimide and polyamideimide. The polyimide refers to a polymer having an imide bond (-CONCO-) in the main chain. In addition, the polyamideimide refers to a polymer having an amide bond and an imide bond in the molecule.

[0072] The polyimide is a polymer of a tetracarboxylic dianhydride and a diamine compound. The polyimide preferably contains at least any one of a structural unit derived from pyromellitic dianhydride and a structural unit derived from 3,3',4,4'-biphenyltetracarboxylic dianhydride, and preferably contains a structural unit derived from 4,4'-diaminodiphenyl ether. In addition, more preferably, the tetracarboxylic dianhydride is either or both of pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride, and the diamine compound is 4,4'-diaminodiphenyl ether. Thereby, better adhesion can be achieved between the conductor 11 and the adhesion layer 13 (in other words, between the conductor 11 and the film 12).

[0073] Preferably, the polyamideimide is a polymer of a tricarboxylic anhydride and a diisocyanate compound. The tricarboxylic anhydride is trimellitic anhydride, and the diisocyanate compound is diphenylmethane diisocyanate. Thereby, better adhesion can be achieved between the conductor 11 and the adhesion layer 13 (in other words, between the conductor 11 and the film 12).

[0074] The weight-average molecular weight of the first resin is preferably 5000 or more and 100000 or less. Thereby, it is possible to balance both ensuring the mechanical strength of the above-mentioned adhesion layer 13 and ensuring the coatability of the resin varnish used when forming the adhesion layer 13. Herein, "mechanical strength" refers to the resistance to breakage of the adhesion layer 13 caused by bending of the insulated wire 1. In addition, the weight-average molecular weight of the first resin is more preferably 20000 or more and 90000 or less, and further preferably 40000 or more and 80000 or less.

[0075] In the adhesion layer 13, the weight-average molecular weight of the first resin can be determined by measurement using gel permeation chromatography (GPC) in accordance with JIS-K7252-1:2008 "Plastics - Methods for determining the average molecular weight and molecular weight distribution of polymers by size exclusion chromatography - Part 1: General rules".

[0076] It was confirmed that: as long as the measurement is performed on the same insulated wire 1, even if the measurement site is arbitrarily selected, there is no deviation in the measurement results.

[0077] The content of the first resin is preferably 50% by mass or more and 100% by mass or less with respect to the adhesion layer 13. Thereby, it is possible to make the adhesion between the conductor 11 and the adhesion layer 13 (in other words, between the conductor 11 and the coating 12) more excellent. The content of the first resin is more preferably 65% by mass or more and 100% by mass or less with respect to the adhesion layer 13, and further preferably 80% by mass or more and 100% by mass or less.

[0078] It should be noted that, in the adhesion layer 13, the content [% by mass] of the first resin can be determined by the following method. That is, the content [% by mass] of the first resin in the adhesion layer 13 can be obtained by performing compositional analysis represented by NMR measurement after chemical decomposition of the adhesion layer 13.

[0079] It was confirmed that: as long as the measurement is performed on the same insulated wire 1, even if the measurement site is arbitrarily selected, there is no deviation in the measurement results.

[0080] (Filler)

[0081] Examples of the filler include silica particles, alumina particles, talc particles, boron nitride particles, and the like.

[0082] (Curing agent)

[0083] This curing agent has the function of curing resins. Specifically, examples include imidazole, triethylamine, titanium compounds, isocyanate compounds, blocked isocyanates, urea, melamine compounds, acetylene derivatives, alicyclic anhydrides such as methyltetrahydrophthalic anhydride, aliphatic anhydrides, and aromatic anhydrides. Examples of the titanium compounds include tetrapropyl titanate, tetraisopropyl titanate, tetramethyl titanate, tetrabutyl titanate, tetrahexyl titanate, etc. Examples of the isocyanate compounds include aromatic diisocyanates such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), p-phenylene diisocyanate, naphthalene diisocyanate; aliphatic diisocyanates having 3 to 12 carbon atoms such as hexamethylene diisocyanate (HDI), 2,2,4-trimethylhexane diisocyanate, lysine diisocyanate; alicyclic isocyanates having 5 to 18 carbon atoms such as 1,4-cyclohexane diisocyanate (CDI), isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), methylcyclohexane diisocyanate, isopropylidene dicyclohexyl-4,4'-diisocyanate, 1,3-diisocyanatomethylcyclohexane (hydrogenated XDI), hydrogenated TDI, 2,5-bis(isocyanatomethyl)-bicyclo[2,2,1]heptane, 2,6-bis(isocyanatomethyl)-bicyclo[2,2,1]heptane; aliphatic diisocyanates having an aromatic ring such as xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI); modified products thereof, etc. Examples of the blocked isocyanates include diphenylmethane-4,4'-diisocyanate (MDI), diphenylmethane-3,3'-diisocyanate, diphenylmethane-3,4'-diisocyanate, diphenyl ether-4,4'-diisocyanate, benzophenone-4,4'-diisocyanate, diphenyl sulfone-4,4'-diisocyanate, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, naphthalene-1,5-diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, etc. Examples of the melamine compounds include methylated melamine, butylated melamine, hydroxymethylated melamine, hydroxybutylated melamine, etc. Examples of the acetylene derivatives include ethynylaniline, ethynylphthalic anhydride, etc.

[0084] (Other additives)

[0085] Examples of the other additives include antioxidants, ultraviolet ray absorbers, lubricity imparting agents, etc.

[0086] (Resins other than the first resin)

[0087] Examples of the "resin other than the first resin" include polyvinyl formal, thermosetting polyurethane, thermosetting acrylic, epoxy resin, thermosetting polyester, thermosetting polyesterimide, thermosetting polyester amide imide, aromatic polyamide, polyphenyl sulfone, polyphenylene sulfide, polyetherimide, polyether ether ketone, polyethersulfone, thermally decomposable resin, and the like.

[0088] <Structure of the adhesion layer>

[0089] The thickness of the adhesion layer 13 is preferably 1 μm or more and 20 μm or less. When the thickness of the adhesion layer 13 is less than 1 μm, sufficient adhesion force may not be obtained due to the too thin adhesion layer 13. When the thickness of the adhesion layer 13 exceeds 20 μm, the residual stress in the adhesion layer 13 increases, and thus the adhesion layer 13 may be easily peeled off from the conductor 11.

[0090] The thickness of the adhesion layer 13 refers to the average value of the thicknesses of the adhesion layer 13 on two pairs of opposite surfaces (upper surface, lower surface, left surface, and right surface) of the outer peripheral surface of the coated conductor 11 in a cross section obtained by cutting the insulated wire 1 with a plane perpendicular to the long dimension direction of the insulated wire 1. Specifically, first, the cross section obtained by cutting the insulated wire 1 with a plane perpendicular to the long dimension direction of the insulated wire 1 is polished to prepare a measurement target surface. Then, the measurement target surface is photographed using a digital microscope VHX-7000 (manufactured by KEYENCE CORPORATION) to obtain an image. Finally, as the thickness of the adhesion layer 13 on two pairs of opposite surfaces of the outer peripheral surface of the coated conductor 11 in this image, for example, one location can be selected from each of the upper surface, lower surface, left surface, and right surface of the conductor 11, and the average value can be calculated based on the values obtained by measuring the thicknesses of the adhesion layer 13 at these four locations in total, and this average value is taken as the thickness of the adhesion layer 13.

[0091] It was confirmed that as long as the measurement is performed on the same insulated wire 1, there is no deviation in the measurement results even if the measurement location is arbitrarily selected.

[0092] <Insulation layer>

[0093] <Composition of the insulation layer>

[0094] The coating 12 includes an insulation layer 14 formed on the adhesion layer 13 ( Figure 1 ). The insulation layer 14 includes a second resin. It should be noted that here, "including the second resin" means that the insulation layer 14 may further include, for example, the filler, the curing agent, the other additives, "resins other than the second resin", etc. as components other than the second resin. In addition, "including the insulation layer 14 formed on the adhesion layer 13" includes the case where the insulation layer 14 is in contact with the adhesion layer 13 ( Figure 1) and the concept of both cases where the insulating layer 14 and the adhesion layer 13 are not in contact (not shown). In the case where the insulating layer 14 and the adhesion layer 13 are not in contact, the film 12 may further include an "intermediate layer" ("other layer") located between the insulating layer 14 and the adhesion layer 13.

[0095] (Second resin)

[0096] The second resin is one or more selected from the group consisting of polyimide and polyamideimide. Polyimide is a polymer having an imide bond (-CONCO-) in the main chain. Polyamideimide is a polymer having an amide bond and an imide bond in the molecule.

[0097] Preferably, the polyimide is a polymer of a tetracarboxylic dianhydride and a diamine compound, the tetracarboxylic dianhydride is either or both of pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride, and the diamine compound is 4,4'-diaminodiphenyl ether. Thereby, better adhesion can be achieved between the conductor 11 and the adhesion layer 13 (in other words, between the conductor 11 and the film 12).

[0098] Preferably, the polyamideimide is a polymer of a tricarboxylic anhydride and a diisocyanate compound, the tricarboxylic anhydride is trimellitic anhydride, and the diisocyanate compound is diphenylmethane diisocyanate. Thereby, better adhesion can be achieved between the conductor 11 and the adhesion layer 13 (in other words, between the conductor 11 and the film 12).

[0099] The weight average molecular weight of the second resin is preferably 5000 or more and 100000 or less. Thereby, both ensuring the mechanical strength of the insulating layer 14 and ensuring the coatability of the resin varnish used when forming the insulating layer 14 can be achieved. The weight average molecular weight of the second resin is more preferably 10000 or more and 50000 or less, and further preferably 15000 or more and 25000 or less.

[0100] The weight average molecular weight of the second resin can be determined by the same method as the "weight average molecular weight of the first resin", except that the measurement is performed in the insulating layer.

[0101] The content of the second resin is preferably 50% by mass or more and 100% by mass or less with respect to the insulating layer 14. Thereby, the mechanical strength of the insulating layer 14 can be ensured, the coatability of the resin varnish used when forming the insulating layer 14 can be ensured, and the insulation property as an insulating film can be provided. In addition, the content of the second resin is more preferably 80% by mass or more and 100% by mass or less with respect to the insulating layer 14, and further preferably 90% by mass or more and 100% by mass or less.

[0102] Note that in the insulating layer 14, the content [mass%] of the second resin can be determined by the following method. That is, the content [mass%] of the second resin in the insulating layer 14 can be obtained by performing compositional analysis represented by NMR measurement after chemical decomposition of the insulating layer 14.

[0103] <Structure of Insulating Layer>

[0104] The thickness of the insulating layer 14 is preferably 4 μm or more and 480 μm or less. When the thickness of the insulating layer 14 does not reach 4 μm or more, there is a tendency for the insulating layer 14 to be easily damaged, and the insulation of the insulating layer 14 may become insufficient. When the thickness of the insulating layer 14 exceeds 480 μm or less, there is a tendency for the volume power of coils etc. formed using the insulated electric wire 1 to become low.

[0105] The thickness of the insulating layer 14 refers to the average value of the thickness of the insulating layer 14 in the cross-section of the insulated electric wire 1. Further details including its measurement method are described below. Specifically, first, microscopic images of any five cross-sections of the insulated electric wire 1 are obtained by a scanning electron microscope (SEM). Next, when the insulating layer 14 is located on the outermost surface of the coating 12, any 5 points are selected on the outer periphery (outermost surface) of the insulated electric wire 1 in each of the above microscopic images, and the shortest distance from the outer periphery to the interface of the insulating layer 14 on the conductor side is obtained at each point, and this shortest distance is taken as the thickness of the insulating layer. In addition, when the insulating layer 14 is not located on the outermost surface of the coating 12, any 5 points are selected on the interface on the surface side of the insulating layer 14 in each of the above microscopic images, and the shortest distance from the interface on the surface side of the insulating layer 14 to the interface of the insulating layer 14 on the conductor side is obtained at each point, and this shortest distance is taken as the thickness of the insulating layer. The average value can be calculated based on the values obtained by measuring the thickness of the insulating layer 14 at a total of 25 locations, and this average value is taken as the thickness of the insulating layer 14. Note that in the above measurement, if there are obvious outliers, the outliers are excluded to calculate the average value. If there are 3 or more outliers, instead, the same number of additional measurements are further performed, and the values obtained therefrom are used to calculate the average value.

[0106] <Other Layers>

[0107] The coating 12 may further include the other layer. As the other layer, for example, a surface layer, an intermediate layer, etc. may be included. In addition, the coating 12 may include an insulating layer having a structure different from that of the insulating layer 14 of the present disclosure.

[0108] <Manufacturing Method of Insulated Electric Wire>

[0109] The insulated electric wire 1 of the present embodiment can be manufactured, for example, by the following method for manufacturing the insulated electric wire 1. That is, the method for manufacturing the insulated electric wire 1 of the present embodiment may sequentially include: a step of preparing a conductor 11, a resin varnish for forming a bonding layer (the resin composition of Embodiment 2), and a resin varnish for forming an insulating layer (first step); a step of coating the resin varnish for forming a bonding layer (the resin composition of Embodiment 2) (second step); a step of baking the resin varnish for forming a bonding layer (the resin composition of Embodiment 2) (third step); a step of coating the resin varnish for forming an insulating layer (fourth step); and a step of baking the resin varnish for forming an insulating layer (fifth step). In addition, the first step includes: a step of preparing a conductor 11 (step A); a step of preparing a resin varnish for forming a bonding layer (the resin composition of Embodiment 2) (step B); and a step of preparing a resin varnish for forming an insulating layer (step C).

[0110] 《First Step》

[0111] <Step A>

[0112] The step of preparing the conductor 11 (step A) can be carried out, for example, by obtaining a commercially available product. In addition, this step can also be carried out by casting the above-mentioned metal as the material of the conductor 11, performing stretching, drawing it into a wire shape, and further softening it to obtain the conductor 11.

[0113] <Step B>

[0114] The step of preparing the resin varnish for forming a bonding layer (the resin composition of Embodiment 2) (step B) can be carried out, for example, according to the following steps. First, after dissolving a tetracarboxylic dianhydride and a diamine compound as raw materials of a polyamic acid (a polyimide precursor) in a solvent, the polycondensation reaction of the tetracarboxylic dianhydride and the diamine compound is promoted, and / or after dissolving a tricarboxylic anhydride and a diisocyanate compound as raw materials of the polyamideimide in the solvent, the polycondensation reaction of the tricarboxylic anhydride and the diisocyanate compound is promoted, thereby obtaining a resin varnish. Then, the nitrogen-containing organic compound is dissolved in the resin varnish, thereby obtaining the resin varnish for forming a bonding layer (the resin composition of Embodiment 2). The tetracarboxylic dianhydride, the diamine compound, the tricarboxylic anhydride, and the diisocyanate compound can be obtained by purchasing commercially available products. In addition, the solvent can be obtained by purchasing a commercially available product.

[0115] The mass part of the nitrogen-containing organic compound relative to 100 mass parts of the resin varnish for forming the sealing layer (the resin composition of Embodiment 2) is preferably 0.0018 mass parts or more, more preferably 0.01 mass parts or more, and still more preferably 0.1 mass parts or more. The mass part of the nitrogen-containing organic compound relative to 100 mass parts of the resin varnish for forming the sealing layer (the resin composition of Embodiment 2) is preferably 1.55 mass parts or less, more preferably 1.0 mass parts or less, and still more preferably 0.8 mass parts or less. The mass part of the nitrogen-containing organic compound relative to 100 mass parts of the resin varnish for forming the sealing layer (the resin composition of Embodiment 2) is preferably 0.0018 mass parts or more and 1.55 mass parts or less, more preferably 0.01 mass parts or more and 1.0 mass parts or less, and still more preferably 0.1 mass parts or more and 0.8 mass parts or less.

[0116] The total of the mass parts of polyamic acid in terms of polyimide conversion and the mass parts of polyamideimide relative to 100 mass parts of the resin varnish for forming the sealing layer (the resin composition of Embodiment 2) is preferably 18 mass parts or more, more preferably 19 mass parts or more, and still more preferably 20 mass parts or more. The total is preferably 31 mass parts or less, more preferably 30 mass parts or less, and still more preferably 29 mass parts or less. The total is preferably 18 mass parts or more and 31 mass parts or less, more preferably 19 mass parts or more and 30 mass parts or less, and still more preferably 20 mass parts or more and 29 mass parts or less.

[0117] As the solvent, known organic solvents can be used. Specifically, examples include polar organic solvents such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, tetramethylurea, hexaethylphosphoric triamide, and γ-butyrolactone; ketone-based organic solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester-based organic solvents such as methyl acetate, ethyl acetate, butyl acetate, and diethyl oxalate; ether-based organic solvents such as diethyl ether, ethylene glycol dimethyl ether, diethylene glycol monomethyl ether, ethylene glycol monobutyl ether (butyl cellosolve), diethylene glycol dimethyl ether, and tetrahydrofuran; hydrocarbon-based organic solvents such as hexane, heptane, benzene, toluene, and xylene; halogen-based organic solvents such as dichloromethane and chlorobenzene; phenol-based organic solvents such as cresol and chlorophenol; and amine-based organic solvents such as pyridine. These organic solvents can be used alone or in combination of two or more.

[0118] The mass part of the solvent relative to 100 mass parts of the resin varnish for forming the sealing layer (the resin composition of Embodiment 2) is preferably 67 mass parts or more, more preferably 68 mass parts or more, and still more preferably 69 mass parts or more. The mass part of the solvent relative to 100 mass parts of the resin varnish for forming the sealing layer (the resin composition of Embodiment 2) is preferably 82 mass parts or less, more preferably 81 mass parts or less, and still more preferably 80 mass parts or less. The mass part of the solvent relative to 100 mass parts of the resin varnish for forming the sealing layer (the resin composition of Embodiment 2) is preferably 67 mass parts or more and 82 mass parts or less, more preferably 68 mass parts or more and 81 mass parts or less, and still more preferably 69 mass parts or more and 80 mass parts or less.

[0119] Herein, the resin varnish for forming the sealing layer (the resin composition of Embodiment 2) may further contain the above-mentioned filler, curing agent, other additives, "resins other than polyamic acid and polyamideimide" described later, etc. in addition to the nitrogen-containing organic compound, one or more selected from the group consisting of the polyamic acid and the polyamideimide, and the solvent.

[0120] The step B is preferably carried out by mixing the above components under the conditions that the stirring time is 30 minutes or more and 10 hours or less, the stirring speed is 100 rpm or more and 300 rpm or less, and the stirring temperature is 10°C or more and 180°C or less.

[0121] <Step C>

[0122] The step of preparing the resin varnish for forming the insulating layer (Step C) can be carried out, for example, according to the following steps. First, after dissolving the tetracarboxylic dianhydride and the diamine compound, which are the raw materials of the polyamic acid (polyimide precursor), in the solvent, the polycondensation reaction of the tetracarboxylic dianhydride and the diamine compound is promoted, and / or after dissolving the tricarboxylic anhydride and the diisocyanate compound, which are the raw materials of the polyamideimide, in the solvent, the polycondensation reaction of the tricarboxylic anhydride and the diisocyanate compound is promoted, thereby obtaining the resin varnish for forming the insulating layer. The tetracarboxylic dianhydride, the diamine compound, the tricarboxylic anhydride, and the diisocyanate compound can be obtained by purchasing commercially available products. In addition, the solvent can be obtained by purchasing commercially available products.

[0123] The total mass parts of polyamic acid in terms of polyimide and polyamide-imide relative to 100 mass parts of the resin varnish for forming the insulating layer is preferably 18 mass parts or more, more preferably 19 mass parts or more, and further preferably 20 mass parts or more. The total is preferably 36 mass parts or less, more preferably 34 mass parts or less, and further preferably 32 mass parts or less. The total is preferably 18 mass parts or more and 36 mass parts or less, more preferably 19 mass parts or more and 34 mass parts or less, and further preferably 20 mass parts or more and 32 mass parts or less.

[0124] The mass parts of the solvent relative to 100 mass parts of the resin varnish for forming the insulating layer is preferably 64 mass parts or more, more preferably 66 mass parts or more, and further preferably 68 mass parts or more. The mass parts of the solvent relative to 100 mass parts of the resin varnish for forming the insulating layer is preferably 82 mass parts or less, more preferably 81 mass parts or less, and further preferably 80 mass parts or less. The mass parts of the solvent relative to 100 mass parts of the resin varnish for forming the insulating layer is preferably 64 mass parts or more and 82 mass parts or less, more preferably 66 mass parts or more and 81 mass parts or less, and further preferably 68 mass parts or more and 80 mass parts or less.

[0125] Here, the resin varnish for forming the insulating layer, in addition to one or more selected from the group consisting of the polyamic acid and the polyamide-imide and the solvent, may further contain the above-mentioned filler, curing agent, other additives, "resins other than polyamic acid and polyamide-imide" described later, and the like.

[0126] The C step is preferably carried out by mixing the above components under the conditions that the stirring time is 30 minutes or more and 10 hours or less, the stirring speed is 100 rpm or more and 300 rpm or less, and the stirring temperature is 10 °C or more and 180 °C or less.

[0127] <Second Step>

[0128] The step of coating the resin varnish for forming the adhesion layer (the resin composition of Embodiment 2) (the second step) is a step of coating the prepared resin varnish for forming the adhesion layer (the resin composition of Embodiment 2) on the outer peripheral surface of the conductor 11. The coating method is not particularly limited, and a conventionally known coating method can be used. For example, in the case of using a coating die having an opening, the varnish can be coated with a uniform thickness, and the surface of the coated varnish can be made smooth.

[0129] <Third Step>

[0130] The process of baking the resin varnish for forming the sealing layer (the resin composition of Embodiment 2) (the third process) is a process of forming the sealing layer 13 in contact with the conductor 11 by baking treatment. Specifically, the conductor 11 coated with the resin varnish for forming the sealing layer (the resin composition of Embodiment 2) is placed in a heating furnace, and the resin varnish for forming the sealing layer (the resin composition of Embodiment 2) is baked. The process of baking the resin varnish for forming the sealing layer (the resin composition of Embodiment 2) to the conductor 11 (the third process) is preferably carried out under the following conditions.

[0131] (Condition)

[0132] Line speed: 3.3 - 4.6 m / min (high line speed)

[0133] Heating furnace inlet temperature: 330 - 350 °C

[0134] Heating furnace outlet temperature: 430 - 450 °C

[0135] <Fourth process>

[0136] The process of coating the resin varnish for forming the insulating layer (the fourth process) is a process of coating the prepared resin varnish for forming the insulating layer on the outer periphery of the sealing layer 13. The coating method is not particularly limited, and a conventionally well-known coating method can be used. For example, in the case of using a coating die having an opening, the resin varnish for forming the insulating layer can be coated with a uniform thickness, and the surface of the coated resin varnish for forming the insulating layer can be made smooth.

[0137] <Fifth process>

[0138] The process of baking the resin varnish for forming the insulating layer (the fifth process) is a process of forming the insulating layer 14 on the outer periphery of the sealing layer 13 by baking treatment. Specifically, the conductor 11 in contact with the sealing layer 13 coated with the resin varnish for forming the insulating layer is placed in a heating furnace, and the resin varnish for forming the insulating layer is baked. The process of baking the resin varnish for forming the insulating layer (the fifth process) is preferably carried out under the following conditions.

[0139] (Condition)

[0140] Line speed: 3.3 - 4.6 m / min (high line speed)

[0141] Heating furnace inlet temperature: 330 - 350 °C

[0142] Heating furnace outlet temperature: 430 - 450 °C

[0143] The insulating wire 1 is manufactured in the above-described manner. The insulating wire 1 includes a conductor 11 and a coating film 12 that coats the conductor 11. The coating film 12 includes: an adhesion layer 13 that is in contact with the conductor 11; and an insulating layer 14 that is formed on the adhesion layer 13. The adhesion layer 13 includes a nitrogen-containing organic compound and a first resin, and the insulating layer 14 includes a second resin. The first resin and the second resin are each one or more selected from the group consisting of polyimide and polyamideimide. The ratio of the total atomic weight of the nitrogen atoms constituting the nitrogen-containing organic compound to the molecular weight of the nitrogen-containing organic compound is 60% or more. It should be noted that the second process and the third process, and both or either of the fourth process and the fifth process can be repeated until the adhesion layer 13 and the insulating layer 14 laminated on the conductor reach a specified thickness.

[0144] <Other Processes>

[0145] When the coating film includes the other layer, the other layer can be formed by a conventionally known method.

[0146] [Embodiment 2: Resin Composition]

[0147] The resin composition of the present embodiment will be described. The resin composition of the present embodiment is a resin composition for the adhesion layer of an insulating wire. The resin composition contains a nitrogen-containing organic compound, a solvent, and one or more selected from the group consisting of polyamic acid and polyamideimide. The ratio of the total atomic weight of the nitrogen atoms constituting the nitrogen-containing organic compound to the molecular weight of the nitrogen-containing organic compound is 60% or more. It should be noted that in the present application, the "mass of the resin composition" refers to the mass after converting the mass of "polyamic acid" to the mass of "polyimide".

[0148] According to the resin composition of the present disclosure, an insulating wire having excellent adhesion between the conductor and the coating film can be provided even when manufactured under the manufacturing conditions of an insulating wire with a high linear velocity.

[0149] <Composition of the Resin Composition>

[0150] The resin composition contains a nitrogen-containing organic compound, a solvent, and one or more selected from the group consisting of polyamic acid and polyamideimide. Here, the nitrogen-containing organic compound refers to the same compound as the nitrogen-containing organic compound in Embodiment 1. The solvent refers to the same compound as the solvent in Embodiment 1. "Containing a nitrogen-containing organic compound, a solvent, and one or more selected from the group consisting of polyamic acid and polyamideimide" means that the resin composition may be composed of the nitrogen-containing organic compound, the solvent, and one or more selected from the group consisting of polyamic acid and polyamideimide, or the resin composition may further contain, for example, a filler, a curing agent, other additives, "resins other than polyamic acid and polyamideimide", etc. as components other than the nitrogen-containing organic compound, the solvent, and one or more selected from the group consisting of polyamic acid and polyamideimide. Here, the filler refers to the same filler as the filler in Embodiment 1. In addition, the curing agent refers to the same curing agent as the curing agent in Embodiment 1. In addition, other additives refer to the same additives as the other additives in Embodiment 1. In addition, examples of "resins other than polyamic acid and polyamideimide" include polyvinyl formal, thermosetting polyurethane, thermosetting acrylic, epoxy resin, thermosetting polyester, thermosetting polyesterimide, thermosetting polyester amideimide, aromatic polyamide, polyphenyl sulfone, polyphenylene sulfide, polyetherimide, polyether ether ketone, polyether sulfone, thermally decomposable resin, etc.

[0151] <Nitrogen-containing organic compound>

[0152] The content of the nitrogen-containing organic compound is preferably 0.0018% by mass or more and 1.55% by mass or less with respect to the resin composition. Thus, in the adhesion layer of the insulated wire, the content of the nitrogen-containing organic compound can be set to 0.01% by mass or more and 5.0% by mass or less with respect to the adhesion layer. Therefore, near the conductor interface, it is easy to ensure a sufficient content of the nitrogen-containing organic compound for the adhesion between the conductor and the adhesion layer. Therefore, even when manufactured under the manufacturing conditions of an insulated wire with a high wire speed, better adhesion between the conductor and the film can be achieved. The lower limit of the content of the nitrogen-containing organic compound is preferably 0.0018% by mass or more, more preferably 0.01% by mass or more, and further preferably 0.1% by mass or more with respect to the resin composition. The upper limit of the content of the nitrogen-containing organic compound is preferably 1.55% by mass or less, more preferably 1.0% by mass or less, and further preferably 0.8% by mass or less with respect to the resin composition. In addition, the content of the nitrogen-containing organic compound is more preferably 0.01% by mass or more and 1.0% by mass or less, and further preferably 0.1% by mass or more and 0.8% by mass or less with respect to the resin composition.

[0153] It should be noted that in this resin composition, the content of the nitrogen-containing organic compound can be determined by the following method. That is, the resin composition can be subjected to LC / MS measurement or the like, thereby obtaining the mass of the nitrogen-containing organic compound. Based on the mass of the nitrogen-containing organic compound and the "mass of the resin composition" determined by the method described below, the content of the nitrogen-containing organic compound in the resin composition is measured.

[0154] <Polyamic acid and polyamideimide>

[0155] Polyamic acid is a precursor of polyimide and is an organic compound that becomes polyimide when imidized by heating (for example, heating by baking a varnish containing the polyamic acid). Preferably, the polyamic acid is a polymer of a tetracarboxylic dianhydride and a diamine compound. The tetracarboxylic dianhydride is either or both of pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride, and the diamine compound is 4,4'-diaminodiphenyl ether. Thus, in the insulated wire, better adhesion can be achieved between the conductor and the adhesion layer (in other words, between the conductor and the film).

[0156] Polyamideimide refers to the same compound as the polyamideimide of the first resin in Embodiment 1.

[0157] The total content of the polyamic acid in terms of polyimide conversion and the content of polyamideimide is preferably 18% by mass or more and 31% by mass or less relative to the resin composition. Thus, in the insulated wire, better adhesion can be achieved between the conductor and the adhesion layer (in other words, between the conductor and the film). The lower limit of the total is preferably 18% by mass or more, more preferably 19% by mass or more, and still more preferably 20% by mass or more relative to the resin composition. The upper limit of the total is preferably 31% by mass or less, more preferably 30% by mass or less, and still more preferably 29% by mass or less relative to the resin composition. The total is more preferably 19% by mass or more and 30% by mass or less, and still more preferably 20% by mass or more and 29% by mass or less relative to the resin composition.

[0158] It should be noted that in this resin composition, the total [mass%] can be determined by the following method. That is, first, the actual mass of the resin composition is obtained. Next, the resin composition is heated at a temperature equal to the boiling point of the solvent for 2 hours to remove the solvent, and the amount of the remaining solid component is obtained. Then, the mass of the nitrogen-containing organic compound contained in the remaining solid component is obtained by the same method as the method for measuring the content of the nitrogen-containing organic compound in the resin composition described in Embodiment 2. The mass of the nitrogen-containing organic compound is subtracted from the amount of the remaining solid component, whereby the total of the "actual mass of polyamic acid", the "mass of polyamideimide", and the above-mentioned "components other than the nitrogen-containing organic compound and the first resin" is obtained. Next, by performing a composition analysis represented by NMR measurement after chemical decomposition of the remaining solid component, the actual mass of polyamic acid and the mass of polyamideimide are calculated. Based on the actual mass of polyamic acid, the "mass of polyamic acid converted to polyimide" is calculated. Then, the proportion of the sum of the "mass of polyamic acid converted to polyimide" and the "mass of polyamideimide" in the difference between the "actual mass of the resin composition" and the "actual mass of polyamic acid" and the sum of the "mass of polyamic acid converted to polyimide" (i.e., the above-mentioned "mass of the resin composition") can be calculated as a percentage, whereby the total [mass%] is obtained.

[0159] <Solvent>

[0160] The content of the solvent is preferably 64 mass% or more and 82 mass% or less with respect to the resin composition. Thereby, the coatability of the resin composition can be improved. The lower limit of the content of the solvent is preferably 64 mass% or more, more preferably 66 mass% or more, and further preferably 68 mass% or more with respect to the resin composition. The upper limit of the content of the solvent is preferably 82 mass% or less, more preferably 81 mass% or less, and further preferably 80 mass% or less with respect to the resin composition. The content of the solvent is more preferably 66 mass% or more and 81 mass% or less, and further preferably 68 mass% or more and 80 mass% or less with respect to the resin composition.

[0161] Note that, in this resin composition, the content [mass%] of the solvent can be determined by the following method. That is, first, the actual mass of the resin composition is obtained. Next, the resin composition is heated at a temperature equal to the boiling point of the solvent for 2 hours to remove the solvent, and the amount of the remaining solid component is obtained. Next, the difference between the actual mass of the resin composition and the amount of the solid component is calculated. Next, as described above, the difference between the "actual mass of the resin composition" and the "actual mass of the polyamic acid" and the sum of the "mass of the polyamic acid in terms of polyimide" are obtained. The content [mass%] of the solvent can be obtained by calculating the ratio (percentage) of the "difference between the actual mass of the resin composition and the amount of the solid component" in the sum.

[0162] "Use of the Resin Composition"

[0163] This resin composition is a resin composition for the adhesion layer of an insulated wire.

[0164] "Manufacturing Method of the Resin Composition"

[0165] The resin composition of the present embodiment can be obtained, for example, by the same method as the B process in the manufacturing method of the insulated wire of Embodiment 1.

[0166] [Supplementary Note 1]

[0167] An insulated wire, which includes a conductor and a coating covering the conductor, the coating including: an adhesion layer in contact with the conductor; and an insulating layer formed on the adhesion layer, the adhesion layer including a nitrogen-containing organic compound and a first resin, the insulating layer including a second resin, the first resin and the second resin being each one or more selected from the group consisting of polyimide and polyamideimide, and the ratio of the total atomic weight of the nitrogen atoms constituting the nitrogen-containing organic compound to the molecular weight of the nitrogen-containing organic compound being 60% or more.

[0168] [Supplementary Note 2]

[0169] The insulated wire according to Supplementary Note 1, wherein the content of the nitrogen-containing organic compound is 0.010 mass% or more and 5.0 mass% or less with respect to the adhesion layer.

[0170] [Supplementary Note 3]

[0171] The insulated wire according to Supplementary Note 1 or Supplementary Note 2, wherein the nitrogen-containing organic compound does not have a 1,3,5-triazine ring structure.

[0172] [Supplementary Note 4]

[0173] The insulated electric wire according to any one of Supplementary Notes 1 to 3, wherein the polyimide is a polymer of a tetracarboxylic dianhydride and a diamine compound, the tetracarboxylic dianhydride is either or both of pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride, and the diamine compound is 4,4'-diaminodiphenyl ether.

[0174] [Supplementary Note 5]

[0175] The insulated electric wire according to any one of Supplementary Notes 1 to 4, wherein the polyamideimide is a polymer of a tricarboxylic anhydride and a diisocyanate compound, the tricarboxylic anhydride is trimellitic anhydride, and the diisocyanate compound is diphenylmethane diisocyanate.

[0176] [Supplementary Note 6]

[0177] A resin composition for an adhesion layer of an insulated electric wire, which contains a nitrogen-containing organic compound, a solvent, and one or more selected from the group consisting of polyamic acid and polyamideimide, and the ratio of the total atomic weight of the nitrogen atoms constituting the nitrogen-containing organic compound to the molecular weight of the nitrogen-containing organic compound is 60% or more.

[0178] [Supplementary Note 7]

[0179] The resin composition for an adhesion layer of an insulated electric wire according to Supplementary Note 6, wherein the content of the nitrogen-containing organic compound is 0.0018% by mass or more and 1.55% by mass or less with respect to the resin composition.

[0180] [Supplementary Note 8]

[0181] The resin composition for an adhesion layer of an insulated electric wire according to Supplementary Note 6 or 7, wherein the nitrogen-containing organic compound does not have a 1,3,5-triazine ring structure.

[0182] [Supplementary Note 9]

[0183] The resin composition for an adhesion layer of an insulated electric wire according to any one of Supplementary Notes 6 to 8, wherein the polyamic acid is a polymer of a tetracarboxylic dianhydride and a diamine compound, the tetracarboxylic dianhydride is either or both of pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride, and the diamine compound is 4,4'-diaminodiphenyl ether.

[0184] [Supplementary Note 10]

[0185] The resin composition for an adhesion layer of an insulated electric wire according to any one of Supplementary Notes 6 to 9, wherein the polyamideimide is a polymer of a tricarboxylic anhydride and a diisocyanate compound, the tricarboxylic anhydride is trimellitic anhydride, and the diisocyanate compound is diphenylmethane diisocyanate.

[0186] Example

[0187] The present embodiment will be described in more detail by way of examples. However, the present embodiment is not limited by these examples.

[0188] "Manufacture of Insulated Wire"

[0189] Insulated wires of Specimens 1 to 17 and 101 to 105 were manufactured in the following manner.

[0190] <First Step>

[0191] (Step A)

[0192] A commercially available flat conductor (material: copper) with a thickness of 1.5 mm and a width of 3.0 mm was prepared.

[0193] (Step B)

[0194] (Production of polyimide precursor resin varnish where the tetracarboxylic dianhydride is pyromellitic dianhydride)

[0195] To manufacture the insulated wires of Specimens 1 to 10 - 2, 12, 14, 16, 17, 101 to 105, pyromellitic dianhydride (tetracarboxylic dianhydride) and 4,4'-diaminodiphenyl ether (diamine compound) were dissolved in the solvent described in Table 1 in an equimolar ratio, and then the polymerization reaction was promoted to obtain a polyimide precursor resin varnish (resin varnish) where the tetracarboxylic dianhydride is pyromellitic dianhydride. It should be noted that "NMP" described in the "Compound Name" column of the "Solvent" column in Table 1 means that the solvent is N-methyl-2-pyrrolidone.

[0196] (Production of polyimide precursor resin varnish where the tetracarboxylic dianhydride is 3,3',4,4'-biphenyltetracarboxylic dianhydride)

[0197] To manufacture the insulated wire of Specimen 15, 3,3',4,4'-biphenyltetracarboxylic dianhydride (tetracarboxylic dianhydride) and 4,4'-diaminodiphenyl ether (diamine compound) were dissolved in the solvent described in Table 1 in an equimolar ratio, and then the polymerization reaction was promoted to obtain a polyimide precursor resin varnish (resin varnish) where the tetracarboxylic dianhydride is 3,3',4,4'-biphenyltetracarboxylic dianhydride. It should be noted that "NMP" described in the "Compound Name" column of the "Solvent" column in Table 1 means that the solvent is N-methyl-2-pyrrolidone.

[0198] (Production of polyamideimide resin varnish)

[0199] To produce the insulated wires of Specimens 11 and 13, trimellitic anhydride (tricarboxylic anhydride) and diphenylmethane diisocyanate (diisocyanate compound) were dissolved in the solvent described in Table 1 in an equimolar ratio, and then the polymerization reaction was promoted to obtain a polyamideimide resin varnish (resin varnish).

[0200] (Resin varnish for forming a bonding layer (resin composition))

[0201] To produce the insulated wires of Specimens 1 to 10-2, 12, 14, 16, 17, 101 to 105, a nitrogen-containing organic compound shown in Table 5 was dissolved in the polyimide precursor resin varnish in which the tetracarboxylic dianhydride was pyromellitic dianhydride, thereby preparing a resin varnish for forming a bonding layer (resin composition). In addition, to produce the insulated wire of Specimen 15, a nitrogen-containing organic compound shown in Table 5 was dissolved in the polyimide precursor resin varnish in which the tetracarboxylic dianhydride was 3,3',4,4'-biphenyltetracarboxylic dianhydride, thereby preparing a resin varnish for forming a bonding layer (resin composition). In addition, to produce the insulated wires of Specimens 11 and 13, a nitrogen-containing organic compound shown in Table 5 was dissolved in the above polyamideimide resin varnish, thereby preparing a resin varnish for forming a bonding layer (resin composition). It should be noted that, with respect to 100 parts by mass of this resin varnish for forming a bonding layer (resin composition), the parts by mass of the nitrogen-containing organic compound, one or more parts by mass selected from the group consisting of polyamic acid and polyamideimide, and the parts by mass of the solvent were set as the parts by mass described in Table 1. In Table 1, the expression "polyamic acid / polyamideimide" means "one or more selected from the group consisting of polyamic acid and polyamideimide". In addition, in Table 1, the parts by mass of polyamic acid refer to the parts by mass of polyamic acid in terms of polyimide. The stirring conditions were as described in Table 1.

[0202] [Table 1]

[0203]

[0204] (Step C)

[0205] (Production of polyimide precursor resin varnish in which tetracarboxylic dianhydride is pyromellitic dianhydride)

[0206] To produce the insulated wires of Specimens 1 to 10-2, 13, 14, 16, 17, 101 to 105, pyromellitic dianhydride (tetracarboxylic dianhydride) and 4,4'-diaminodiphenyl ether (diamine compound) were dissolved in the solvent described in Table 2 in an equimolar ratio, and then the polymerization reaction was promoted, whereby a polyimide precursor resin varnish (resin varnish for forming an insulating layer) with pyromellitic dianhydride as the tetracarboxylic dianhydride was obtained. It should be noted that "NMP" described in the "Compound Name" column of the "Solvent" column in Table 2 means that the solvent is N-methyl-2-pyrrolidone.

[0207] (Production of Polyimide Precursor Resin Varnish with 3,3',4,4'-Biphenyltetracarboxylic Dianhydride as the Tetracarboxylic Dianhydride)

[0208] To produce the insulated wire of Specimen 15, 3,3',4,4'-biphenyltetracarboxylic dianhydride (tetracarboxylic dianhydride) and 4,4'-diaminodiphenyl ether (diamine compound) were dissolved in the solvent described in Table 2 in an equimolar ratio, and then the polymerization reaction was promoted, whereby a polyimide precursor resin varnish (resin varnish for forming an insulating layer) with 3,3',4,4'-biphenyltetracarboxylic dianhydride as the tetracarboxylic dianhydride was obtained. It should be noted that "NMP" described in the "Compound Name" column of the "Solvent" column in Table 2 means that the solvent is N-methyl-2-pyrrolidone.

[0209] (Production of Polyamideimide Resin Varnish)

[0210] To produce the insulated wires of Specimens 11 and 12, trimellitic anhydride (tricarboxylic anhydride) and diphenylmethane diisocyanate (diisocyanate compound) were dissolved in the solvent described in Table 2 in an equimolar ratio, and then the polymerization reaction was promoted, whereby a polyamideimide resin varnish (resin varnish for forming an insulating layer) was obtained.

[0211] It should be noted that, with respect to 100 parts by mass of the resin varnish for forming the insulating layer, the parts by mass of the second resin and the solvent were set to the parts by mass described in Table 2. The stirring conditions were as described in Table 2.

[0212] [Table 2]

[0213]

[0214] (Second Process)

[0215] Using a coating die having an opening, the resin varnish for forming the adhesion layer was coated on the outer peripheral surface of the conductor, whereby a conductor coated with the resin varnish for forming the adhesion layer was produced.

[0216] (Third Process)

[0217] Next, the conductor coated with the resin varnish for forming the adhesion layer is placed in a heating furnace and baked under the conditions described in Table 3. It should be noted that here, the line speeds described in Table 3 all conform to high line speeds.

[0218] [Table 3]

[0219]

[0220] The second process and the third process are each carried out once in such a way that the thickness of the adhesion layer of each specimen becomes the thickness of the adhesion layer shown in Table 5, thereby forming an adhesion layer.

[0221] (Fourth process)

[0222] Using a coating die having an opening, the resin varnish for forming the insulating layer is coated on the outer periphery of the adhesion layer, thereby producing a conductor in contact with the adhesion layer coated with the resin varnish for forming the insulating layer.

[0223] (Fifth process)

[0224] Next, the conductor in contact with the adhesion layer coated with the resin varnish for forming the insulating layer is placed in a heating furnace and baked under the conditions described in Table 4. It should be noted that here, the line speeds described in Table 4 all conform to high line speeds.

[0225] [Table 4]

[0226]

[0227] The fourth process and the fifth process are repeatedly carried out in such a way that the thickness of the insulating layer of each specimen becomes the thickness of the insulating layer shown in Table 5, thereby forming an insulating layer.

[0228] By performing the above processes, specimens 1 to 17 and 101 to 105 of insulated wires having the configurations shown in Table 5 are manufactured.

[0229] "Evaluation of the Characteristics of Insulated Wires"

[0230] <Determination of the Content of the Nitrogen-Containing Organic Compound with Respect to the Adhesion Layer>

[0231] For the insulated wires of Samples 1 to 17 and 101 to 105, the content [mass%] of the nitrogen-containing organic compound with respect to the adhesion layer was determined by the method described in Embodiment 1. The results are shown in the column of "Content [mass%]" in Table 5. Note that when all columns of "Compound Name", "Ratio of Total Atomic Weight of N Atoms [%]", "Presence or Absence of 1,3,5-Triazine Ring Structure", "Presence or Absence of S Element", and "Content [mass%]" in the column of "Nitrogen-Containing Organic Compound" in Table 5 are recorded as "-", it means that the adhesion layer does not contain a nitrogen-containing organic compound.

[0232] <Determination of Content of First Resin with Respect to Adhesion Layer>

[0233] For the insulated wires of Samples 1 to 17 and 101 to 105, the content [mass%] of the first resin with respect to the adhesion layer was determined by the method described in Embodiment 1. The results are shown in the column of "Content [mass%]" in the column of "First Resin" in Table 5. Note that "PI" recorded in the column of "Compound Name" in the column of "First Resin" in Table 5 refers to polyimide, and "PAI" refers to polyamideimide.

[0234] <Determination of Content of Second Resin with Respect to Insulation Layer>

[0235] For the insulated wires of Samples 1 to 17 and 101 to 105, the content [mass%] of the second resin with respect to the insulation layer was determined by the method described in Embodiment 1. The results are shown in the column of "Content [mass%]" in the column of "Second Resin" in Table 5. Note that "PI" recorded in the column of "Compound Name" in the column of "Second Resin" in Table 5 refers to polyimide, and "PAI" refers to polyamideimide.

[0236] <Measurement of Coating Thickness>

[0237] For the insulated wires of Samples 1 to 17 and 101 to 105, the thickness [μm] of the coating was determined by the method described in Embodiment 1. The results are shown in the column of "Coating Thickness [μm]" in Table 5.

[0238] <Evaluation of Adhesion between Conductor and Coating>

[0239] For the insulated wires of Samples 1 to 17 and 101 to 105, a cut with a width of 0.5 mm was made up to the interface between the conductor and the adhesion layer, and the adhesion force (conductor adhesion force) [N / mm] between the conductor and the adhesion layer (i.e., the adhesion force between the conductor and the coating) was measured by a 180° peel test. The adhesion between the conductor and the coating was evaluated based on the obtained adhesion force and the following evaluation criteria. The obtained results are shown in the column of "Adhesion" in Table 5.

[0240] (Evaluation Criteria)

[0241] A: Conductor adhesion is 0.7N / mm or more

[0242] B: Conductor adhesion is 0.5N / mm or more and less than 0.7N / mm

[0243] C: Conductor tightness is less than 0.5N / mm

[0244] [Table 5]

[0245]

[0246] The insulated wires of samples 1 to 17 correspond to Examples. The insulated wires of samples 101 to 105 correspond to Comparative Examples. The results in Table 5 show that the insulated wires of samples 1 to 17 have excellent adhesion between the conductor and the coating compared to the insulated wires of samples 101 to 105 even when manufactured under high wire speed manufacturing conditions.

[0247] From the above, it can be seen that the insulated electric wires of Samples 1 to 17 are excellent in the adhesion between the conductor and the coating even when they are produced under the production conditions of high wire speed.

[0248] As mentioned above, although the embodiment and the example of this disclosure were described, it is also planned from the beginning that the configurations of each embodiment and the example described above may be appropriately combined or variously modified.

[0249] The embodiments and examples disclosed herein are illustrative in all respects and should not be construed as limiting. The scope of the present invention is indicated by the claims rather than the embodiments and examples described above, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0250] Description of Reference Numerals

[0251] 1: insulated wire; 11: conductor; 12: coating; 13: sealing layer; 14: insulating layer.

Claims

1. An insulated wire, comprising a conductor and a film covering the conductor, wherein the film includes: an adhesion layer in contact with the conductor; and an insulating layer formed on the adhesion layer, the adhesion layer contains a nitrogen-containing organic compound and a first resin, the insulating layer contains a second resin, the first resin and the second resin are each one or more selected from the group consisting of polyimide and polyamideimide, the proportion of the total atomic weight of nitrogen atoms constituting the nitrogen-containing organic compound relative to the molecular weight of the nitrogen-containing organic compound is 60% or more.

2. The insulated wire according to claim 1, wherein, the content of the nitrogen-containing organic compound is 0.010% by mass or more and 5.0% by mass or less relative to the adhesion layer.

3. The insulated wire according to claim 1 or 2, wherein, the nitrogen-containing organic compound does not have a 1,3,5-triazine ring structure.

4. The insulated wire according to any one of claims 1 to 3, wherein, the polyimide is a polymer of a tetracarboxylic dianhydride and a diamine compound, the tetracarboxylic dianhydride is either or both of pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride, the diamine compound is 4,4'-diaminodiphenyl ether.

5. The insulated wire according to any one of claims 1 to 4, wherein, the polyamideimide is a polymer of a tricarboxylic anhydride and a diisocyanate compound, the tricarboxylic anhydride is trimellitic anhydride, the diisocyanate compound is diphenylmethane diisocyanate.

6. A resin composition for an adhesion layer of an insulated wire, containing a nitrogen-containing organic compound, a solvent, and one or more selected from the group consisting of polyamic acid and polyamideimide, the proportion of the total atomic weight of nitrogen atoms constituting the nitrogen-containing organic compound relative to the molecular weight of the nitrogen-containing organic compound is 60% or more.

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