JPH10125140A - Multi-layer insulating electric wire and transformer using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-layer insulating electric wire having an insulating layer with high heat resistance, high soldering capability, and a transformer formed by winding the insulating electric wire, with high electric characteristics and high reliability. SOLUTION: A multi-layer insulating electric wire has a conductor 6a and two or more extrusion insulating layers 6b-6d capable of soldering, covering the conductor 6a, at least one layer of the insulating layers 6b-6d is formed with a resin mixture of 100 pts.wt. at least one resin (A) selected from polyether imide resin and polyether sulfone resin and 10 pts.wt. or more at least one resin (B) selected from polycarbonate resin, polyarylate resin, polyester resin, and polyamide resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layer insulated wire in which an insulating layer comprises two or more extruded coating layers, and a transformer using the same. A multi-layer insulated wire that has excellent solderability and heat resistance, and is useful as windings and leads for transformers to be incorporated into electric and electronic equipment, etc. It relates to the transformer used.

[0002]

2. Description of the Related Art The structure of a transformer conforms to the IEC standard (Internat
ional Electrotechnical Communication Standard) Pub.
950. That is, according to these standards, at least three layers of insulating layers (enamel films covering conductors are not recognized as insulating layers) are formed between the primary winding and the secondary winding in the winding, The thickness of the layer is 0.4 mm or more, the creepage distance between the primary winding and the secondary winding varies depending on the applied voltage, but is 5 mm or more, and 3000 V is applied to the primary side and the secondary side. It is stipulated that it can withstand more than one minute at times. Under such a standard, as a transformer currently occupying the mainstream, a structure as exemplified in the cross-sectional view of FIG. 2 is employed. An enamel-coated primary winding 4 is wound in a state in which insulating barriers 3 for securing a creepage distance are arranged at both ends of a peripheral surface of a bobbin 2 on a ferrite core 1. A structure in which an insulating tape 5 is wound on at least three layers and an insulating barrier 3 for securing a creepage distance is disposed on the insulating tape, and then a secondary winding 6 also covered with enamel is wound. It is.

In recent years, instead of the transformer having the cross-sectional structure shown in FIG. 2, as shown in FIG.
Transformers having a structure that does not include the insulating tape layer 5 have begun to appear. This transformer is different from the transformer of the structure of FIG.
It is advantageous in that the whole can be reduced in size and that the work of winding the insulating tape can be omitted. When the transformer shown in FIG. 1 is manufactured, one or both of the conductors 4a (6) are used in the primary winding 4 and the secondary winding 6 to be used.
At least three insulating layers 4b (6b), 4
The formation of c (6c) and 4d (6d) is necessary in relation to the IEC standard.

As such a winding, an insulating tape is wound around the conductor to form a first insulating layer, and an insulating tape is further wound thereon to form a second insulating layer and a third insulating layer. Are formed in order to form an insulating layer having a three-layer structure in which the insulating layers are successively formed and separated from each other. Further, there is known a winding in which a fluororesin is sequentially extruded around an outer periphery of a conductor which is enameled with polyurethane, and an extruded coating layer having a three-layer structure is used as an insulating layer as a whole (Japanese Utility Model Application No. 3-56).
No. 112).

However, in the case of the above-mentioned insulating tape winding, since the winding operation is inevitable, the productivity is extremely low, and the cost of the electric wire is very high.
Further, in the case of the above-mentioned fluororesin extrusion, since the insulating layer is formed of a fluororesin, there is an advantage that the heat resistance is good, but the cost of the resin is high and the resin is pulled at a high shear rate. In addition, it is difficult to increase the manufacturing speed because of the property of deteriorating the appearance, and the wire cost becomes high as in the case of insulating tape winding. Furthermore, in the case of this insulating layer, since it cannot be removed even when immersed in a solder bath, for example, at the time of terminal processing performed when connecting an insulated wire to a terminal, the insulating layer of the terminal is mechanically unreliable. There is a problem that it must be peeled off by another means and further soldered or crimped.

[0006] On the other hand, a plurality of extruded insulating layers are formed from a mixture of polyethylene terephthalate as a base resin and an ionomer in which a part of the carboxyl group of an ethylene-methacrylic acid copolymer is converted to a metal salt to form a plurality of extruded insulating layers. A multilayer insulated wire coated with nylon has been put into practical use as the uppermost layer of the layer, which is based on wire cost (material cost and productivity), solderability (that the insulated wire and terminal can be directly connected), and coil workability ( It is excellent in that the insulated layer is not broken due to friction between the insulated wires and rubbing with the guide nozzle when the insulated wires are wound around the bobbin, so that the electrical characteristics of the coil are not deteriorated. Fifth
606,152, JP-A-6-223634). Furthermore, from the above-mentioned polyethylene terephthalate as a base resin to improve heat resistance,
Polycyclohexane dimethylene terephthalate (PC
It has also been proposed that T) be changed to a base resin. However, these have heat resistance of IEC950.
Annex U (Electric Wire) of Section 2.9.4.4 of the standard and 1.5.
In the test method based on Appendix C (transformer) of item 3, heat resistance class E is passed, but it cannot respond to the recent increase in the required level of heat resistance, and heat type B is rejected.

[0007]

SUMMARY OF THE INVENTION In order to solve such a problem, the present invention provides a multilayer insulated wire having excellent heat resistance, solderability and coil workability and suitable for industrial production. With the goal. It is a further object of the present invention to provide a transformer having excellent electrical properties and high reliability formed by winding such an insulated wire having excellent heat resistance, solderability and coil workability.

[0008]

The above objects of the present invention have been attained by the following multilayer insulated wire and a transformer using the same. That is, the present invention relates to (1) a multilayer insulated wire having a conductor and two or more solderable extruded insulating layers covering the conductor, wherein at least one of the insulating layers is
At least one resin selected from a polycarbonate resin, a polyarylate resin, a polyester resin, and a polyamide resin (100 parts by weight of at least one resin (A) selected from a polyetherimide resin and a polyether sulfone resin) (2) A multilayer insulated wire characterized by being formed from a resin blend containing 10 parts by weight or more of (B), (2) the resin (A) is a polyether sulfone resin. (3) The multilayer insulated wire according to (1), wherein the resin (B) is a polycarbonate resin.
(4) The multi-layer insulated wire according to (1), wherein the resin (A) is a polyether sulfone resin, and the resin (B) is a polycarbonate resin. The multilayer insulated wire according to (1), (2), (3) or (4), which is a polyether sulfone resin having a repeating unit represented by the following formula:

[0009]

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(In the formula, n represents a positive integer.) (6) The resin admixture is blended with 10 to 70 parts by weight of the resin (B) based on 100 parts by weight of the resin (A). The multi-layer insulated wire according to any one of (1) to (5), wherein the conductor is preheated to a temperature not exceeding 140 ° C. The multilayer insulated wire according to any one of (1) to (6), wherein the at least one layer is formed of the resin mixture in the insulating layer.
(1)-characterized in that the insulating layer other than the layer is formed of a thermoplastic polyester resin or a polyamide resin.
The multilayer insulated wire according to any one of the above items (7), (9).
The multi-layer insulated wire according to any one of (1) to (8), wherein the uppermost layer of the insulating layer is made of a polyamide resin, and (10) the above-described (1) to (9). A transformer provided by using the multilayer insulated wire according to any one of the aspects is provided.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the multilayer insulated wire of the present invention, the insulating layer comprises two or more layers, preferably three layers. Among the insulating layers, at least one insulating layer made of a mixture of the above-mentioned resins (A) and (B) is preferred, and when importance is placed on heat resistance, all layers are preferably made of this mixture. When emphasis is placed on coil workability, the uppermost layer of the insulating layer is formed of a resin layer having good lubricity, and the other layers are formed of a mixture of the resins (A) and (B). preferable. The resin (A) is a resin having high heat resistance, and a polyether sulfone resin selected from known resins can be used as the resin. As this polyether sulfone resin, those represented by the following general formula (1) are preferably used.

[0012]

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Wherein R ₁ is a single bond or —R ₂ —O—
(R ₂ is a phenylene group, a biphenylylene group,

[0014]

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(R ₃ is —C (CH ₃ ) ₂ —, —CH ₂ —
Etc.), and the group represented by R ₂ may further have a substituent. ). n shows a positive integer. ]

The method of producing the resin is known per se, and as an example, a method of reacting dichlorodiphenylsulfone, bisphenol S and potassium carbonate in a high-boiling-point solvent can be mentioned. Commercially available resins include Victrex PES (trade name, manufactured by Sumitomo Chemical Co., Ltd.) and Radel A / Ledel R. UDEL (trade name, manufactured by Amoco).
Further, a polyetherimide resin can be used as the resin (A). This polyetherimide resin is also known, together with a production method. As an example, 2,2′-bis [3- (3,4-dicarboxyphenoxy) -phenyl] propanedioic anhydride and 4,4′-diaminodiphenylmethane are used. It is synthesized by solution polycondensation using ortho-dichlorobenzene as a solvent. This polyetherimide resin is preferably represented by the general formula (2).

[0017]

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[In the formula, R ₄ and R ₅ may have a substituent; a phenylene group, a biphenylylene group,

[0019]

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(Wherein, R ₆ is preferably an alkylene group having 1 to 7 carbon atoms, and is preferably methylene, ethylene, propylene (particularly preferably isopropylidene)) or a naphthylene group. When has a substituent, examples of the substituent include an alkyl group (eg, methyl and ethyl). m is a positive integer. ] Commercially available resins are ULTEM (GE Plastics,
Product name).

In the present invention, by mixing the heat-resistant resin (A) and the resin (B), the resin composition is given solderability. The polycarbonate resin, polyarylate resin, polyester resin and polyamide resin used as the resin (B) are not particularly limited. As the polycarbonate resin, for example, a resin produced by a known method using dihydric alcohol and phosgene as raw materials can be used. Examples of commercially available resins include Lexan (trade name, manufactured by GE Plastics), Panlite (trade name, manufactured by Teijin Chemicals), Iupilon (trade name, manufactured by Mitsubishi Gas Chemical Company), and the like. Known polycarbonate resins can be used for the present invention. For example, there is one represented by the general formula (3).

[0022]

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[Wherein, R ₇ may have a substituent; a phenylene group, a biphenylylene group,

[0024]

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(Wherein, R ₈ is preferably an alkylene group having 1 to 7 carbon atoms, and is preferably methylene, ethylene, propylene (particularly preferably isopropylidene)) or a naphthylene group. When has a substituent, examples of the substituent include an alkyl group (eg, methyl and ethyl). s is a positive integer. The polyarylate resin is produced by an interfacial polymerization method, and is synthesized by reacting bisphenol A dissolved in an aqueous alkaline solution with tere / iso mixed phthalic chloride dissolved in an organic solvent such as a halogenated hydrocarbon at room temperature. I do. Commercially available resins include U-Polymer (trade name, manufactured by Unitika). As the polyester resin, those produced by a known method using a dihydric alcohol and a divalent aromatic carboxylic acid as raw materials can be used. As commercially available resins, polyethylene terephthalate (PET) -based resins include Viropet (manufactured by Toyobo, trade name), Bellpet (manufactured by Kanebo,
(Trade name), Teijin PET (trade name, manufactured by Teijin Limited). The polyethylene naphthalate (PEN) resin includes Teijin PEN (trade name, manufactured by Teijin Limited), and the polycyclohexane dimethylene terephthalate (PCT) resin includes Ector (trade name, manufactured by Toray Industries, Inc.).

Further, as the polyamide resin, those produced by a known method using diamine, dicarboxylic acid and the like as raw materials can be used. Nylon 6 and 6 are commercially available resins such as Amiran (trade name, manufactured by Toray Industries), Zytel (trade name, manufactured by DuPont), Maranil (trade name, manufactured by Unitika),
Nylon 4 and 6 include Unitika Nylon 46 (product name, manufactured by Unitika), and Nylon 6 and T include Arlen (product name, manufactured by Mitsui Petrochemical Company).

In the present invention, the resin (B) such as a polycarbonate resin, a polyarylate resin, a polyester resin, or a polyamide resin mixed with the heat-resistant resin (A) is mixed with the heat-resistant resin (A). It is presumed that a part of the resin is decomposed at the time of soldering as an insulated wire or an insulated wire to generate components (carboxylic acids, amines, alcohols, aldehydes, etc.) exhibiting a flux action. In the present invention, the resin (B) based on 100 parts by weight of the resin (A)
Is 10 parts by weight or more. When the amount of the resin (B) is less than 10 parts by weight with respect to 100 parts by weight of the resin (A), the heat resistance is high but the solderability is not obtained. The upper limit of the amount of the resin (B) is determined in consideration of the required level of heat resistance, but is preferably 100 parts by weight or less. When a high level of heat resistance is to be realized while maintaining high solderability, the amount of the resin (B) used is preferably not more than 70 parts by weight, and the balance between these two characteristics is particularly good. The range is 20 to 50 parts by weight of the resin (B). Of particular note is that heat-resistant resins such as polyetherimide resin and polyethersulfone resin do not show any solderability, and that polycarbonate resin and polyarylate resin themselves have impractical solderability. Only when both resins are blended can solderability be improved to a practical level. Although polyester resin and polyamide resin alone show good solderability by themselves, it is surprising that even if the mixing ratio is reduced, practical solderability can be exhibited.

The resin admixture can be melt-blended using a conventional kneader such as a twin-screw extruder, a kneader or a co-kneader. It has been found that the kneading temperature of the compounded resin directly affects the solderability, and that the better the direct solderability is, the higher the temperature setting of the kneader during mixing is set. A temperature setting of 320 ° C. or higher, particularly 360 ° C. or higher is preferable. Other heat-resistant thermoplastic resins can be added to the resin mixture as long as the solderability and heat resistance are not impaired. The heat-resistant thermoplastic resin that can be added preferably has good solderability per se, and examples thereof include a polyurethane resin and a polyacryl resin. Additives, inorganic fillers, processing aids, coloring agents, etc., which are usually used, can be added to the resin admixture as long as the solderability and heat resistance are not impaired.

Further, it is preferable that two or more layers of the resin mixture are combined and extruded and coated as a configuration of the insulating layer of the multilayer insulated wire because the balance between the heat resistance and the solderability is good.
As the thermoplastic resin having solderability that can be formed as an insulating layer other than the resin mixture, a resin containing polyamide as a main component and a resin containing polyester as a main component can be used. Specifically, as a polyamide resin, Is nylon 1
2, nylon 6, nylon 6,6, nylon 4,6 and the like can be used. It is particularly preferable to use nylon 6,6 and nylon 4,6 in order to balance the heat resistance and the solderability, and it is most preferable to form them in the uppermost layer in consideration of the coil workability of the electric wire. The polyester resin is composed of an aromatic dicarboxylic acid and an aliphatic diol, and is made of polybutylene terephthalate (P
BT), polyethylene terephthalate (PET), polycyclohexanedimethane terephthalate (PCT), polyethylene naphthalate (PEN) and the like can be used. Next, other resins, additives and the like may be added to the resin mixture or the resin containing the polyamide resin and / or the polyester resin as a main component as long as heat resistance and solderability are not hindered. Absent. Also, when extruding and coating the resin mixture on the conductor, the solderability is greatly improved if the conductor is not preheated. Even when preheating, the temperature is preferably set to a temperature of 140 ° C. or lower.
That is, the adhesiveness between the conductor and the resin mixture coating layer is weakened by not heating the conductor, and the resin mixture coating layer generates a large heat shrinkage of 10 to 30% in the longitudinal direction at the time of soldering. The solderability is improved. The conductor used in the present invention may be a bare metal wire (single wire), an insulated wire in which an enamel coating layer or a thin insulating layer is provided on a bare metal wire, a plurality of bare metal wires, an enamel insulated wire or a thin insulated wire. A multi-core stranded wire obtained by twisting a plurality of wires can be used. The number of stranded wires of these stranded wires can be arbitrarily selected depending on the high frequency application. When the number of cores (elements) is large (for example, 19-, 37-elements), it is not necessary to use stranded wires. When it is not a stranded wire, for example, a plurality of strands may be simply bundled substantially in parallel, or the bundle may be stranded at a very large pitch.
In any case, it is preferable that the cross section be substantially circular. However, the thin insulating material must be a resin having good solderability itself, such as an ester imide-modified polyurethane resin, a urea-modified polyurethane resin, or a polyester imide resin. For example, WD-4305 (trade name, manufactured by Hitachi Chemical Co., Ltd.) , Trade name TSF-20 manufactured by Totoku Paint Co., Ltd.
0, TPU-7000, trade name FS-30 manufactured by Dainichi Seika
4 etc. can be used. Further, soldering or tin plating on the conductor is also a means for improving the soldering characteristics. According to a preferred embodiment of the present invention, the heat-resistant multilayer insulated wire is
A first layer of resin or a resin mixture is extrusion-coated on the outer periphery of the conductor to form a first insulating layer having a desired thickness, and then a second layer of resin or resin is formed on the outer periphery of the first insulating layer. Extrusion coating of the resin mixture to form a second insulating layer of a desired thickness,
Further, the second insulating layer is manufactured by extrusion-coating the outer periphery of the second insulating layer with a resin or a resin mixture for the third layer to form a third insulating layer having a desired thickness. The total thickness of the extruded coating insulating layer thus formed is 60 to
Preferably, it is within the range of 180 μm.
This means that when the total thickness of the insulating layer is 60 μm or less, the obtained heat-resistant multilayer insulated wire has a large decrease in electrical properties, which may be unsuitable for practical use, and when it is 180 μm or more, the solderability may be significantly deteriorated. It depends. A more preferred range is 70 to 150 μm. The thickness of each of the three layers is preferably controlled to 20 to 60 μm.

The multilayer insulated wire of the present invention has at least one layer of the resin mixture as an insulating layer, and the remaining insulating layer may be a layer mainly composed of a solderable thermoplastic resin. And both properties of heat resistance and solderability can be satisfied. The reason for this is not yet clear, but is presumed as follows. That is, it is important that the resin mixture is a polyetherimide resin having a high heat resistance, a polyether sulfone resin and a polycarbonate resin, a polyarylate resin, a polyester resin, and a polyamide resin having lower heat resistance. In some cases, the resin having low heat resistance is partially decomposed by heat to reduce the molecular weight, lower the melt viscosity of the admixture, and generate a component exhibiting a flux action. Thus, it is considered that when extrusion-coated, solderability can be exhibited despite having high heat resistance. Further, when the resin mixture is formed on the first layer by coating, the heat shrinkability is large, so that the conductor is not preheated, and the solderability can be further improved by lowering the adhesion. There was found. The transformer using the multilayer insulated wire according to the present invention not only satisfies the IEC950 standard, but also can be miniaturized because it is not wrapped with an insulating tape, and has high heat resistance and high-frequency characteristics, so that it is required for severe design. Can also respond.

The multilayer insulated wire according to the present invention is shown in FIGS.
Any type of transformer can be used as a winding, including those shown in. Such transformers usually have a primary winding and a secondary winding wound in layers on a core,
Transformer in which primary winding and secondary winding are alternately wound
152139). In the transformer of the present invention, the above-described multilayer insulated wire may be used for both the primary winding and the secondary winding, but either one of them may be used. When the multilayer insulated wire of the present invention is composed of two layers, (for example, the primary winding and the secondary winding are each made of a two-layer insulated wire, or an enameled wire is used for one and a two-layer insulated wire is used for the other. When an electric wire is used), at least one insulating barrier layer can be interposed between both windings.

[0032]

Next, the present invention will be described in more detail with reference to examples. Examples 1 to 18 and Comparative Examples 1 to 5 Soft copper wire having a wire diameter of 0.4 mm as a conductor and a wire diameter of 0.15
varnished varnish WD-4305 manufactured by Hitachi Chemical Co., Ltd.
Was prepared by twisting seven insulated wire cores each having a thickness of 8 μm. The composition (composition indicates parts by weight) and thickness of the extrusion coating resin of each layer shown in Table 1, Table 2 and Table 3,
A multilayer insulated wire was manufactured by sequentially extruding and coating the conductor (surface treatment: using refrigerating machine oil). Various characteristics of the obtained multilayer insulated wire were measured according to the following specifications.

◎ Solderability: A portion of about 40 mm end of the electric wire was immersed in molten solder at a temperature of 450 ° C.
Measure the time (seconds) until the solder adheres to the mm part.
The shorter this time, the better the solderability.
Numerical values are average values of n = 3. ◎ Heat resistance (1): 2.9.4 of IEC standard 950 standard.
The evaluation was performed by the following test method based on Annex U (electric wire) of Section 4 and Annex C (Transformer) of Section 1.5.3. Diameter 6
Multi-layer insulated wire on mandrel of mm
(12 kg / mm ² ) and 10 turns
Heat at 25 ° C (E type 215 ° C) for 1 hour, and further heat at 175 ° C (E
(Seed 165 ° C) Heated for 72 hours, further maintained in an atmosphere of 25 ° C and 95% for 48 hours, and immediately applied a voltage of 3000 V for 1 minute.
(Evaluation is made when n = 5. If n = 1, the result is NG.コ イ ル Coil workability (static friction coefficient): FIG. 3 shows a method for measuring the static friction coefficient. Reference numeral 7 denotes a multilayer insulated wire, 8 denotes a load plate, and its weight is Wg. Similarly, 9 indicates a pulley and 10 indicates a load. Assuming that the mass of the load 10 when the load plate 8 starts to move is Fg, the obtained static friction coefficient = F / W. The smaller the value, the better the surface slipperiness and the better the coil workability.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

[Table 3]

From the results shown in Tables 1, 2 and 3, the following became clear. Examples 1 to 4 show good solderability and heat resistance because all three layers are formed of the resin mixture within the range specified in the present invention. Example 5,
Since 6, 9 to 11 use a polyamide resin for the third layer, they have good heat resistance and solderability, and have a small static friction coefficient and good coil workability. In Examples 7 and 8, since the polyester resin was used, the coil processability was slightly inferior to the polyamide resin, but the balance was maintained. In Example 12, the resin mixture was used only for the first layer.
The layers are well-balanced because a material having good solderability and relatively good heat resistance is used for the third and third layers, and a polyamide resin is used for the third layer. In Example 13, the preheating temperature was as low as 140 ° C., and in Example 14, no preheating was performed, so that the solderability was further improved. Example 1
In No. 5, since the film thickness is as thick as 180 μm, a decrease in the solderability is observed. In Example 16, since the kneading temperature was set as low as 320 ° C., the solderability was slightly reduced. Embodiments 17 and 18 use enameled stranded wires that can be soldered to conductors, but have the same good properties as single wires.

However, in Comparative Example 1, only the polyetherimide resin was used, and in Comparative Example 2, only the polyether sulfone resin was used.
Since the layer is used, it has high heat resistance but does not show solderability. Comparative Example 3 was made of only polycarbonate resin.
It has almost no heat resistance, poor solderability, and not at a practical level. Further, since Comparative Example 4 was made of only a fluororesin, it was found that the coil workability was good and the heat resistance was high but the solderability was not exhibited as in Comparative Example 1. Comparative Example 5 is out of the range specified by the present invention, and does not exhibit solderability despite good heat resistance despite the fact that the amount of the compounded resin is small and thus the conductor is not preheated. In addition, the appearance of the electric wires has also deteriorated.

Examples 19 to 21 and Comparative Example 6 As shown in Table 4, with respect to the resin admixtures (compositions shown by weight) of the first to third insulating layers, polyether sulfone resin and polycarbonate resin were used. The multilayer insulated wire was manufactured in exactly the same manner as in Example 3 except that the ratio was changed.
Further, as Comparative Example 6, a multilayer insulated wire in which the first and second layers were formed of a resin mixture of polyethylene terephthalate and an ionomer and the third layer was formed of nylon as shown in Table 4 was manufactured. This insulated wire was tested as follows. still,
The reason for adding the heat resistance test (2) in the heat resistance evaluation is that in the heat resistance test (1), the heat resistance can be determined only by the pass / fail of Class B or E, and it is a practical product (Comparative Example 6). In order to show the difference in heat resistance from the above, they were compared by a simple heat resistance evaluation method for enameled wires. ◎ Heat resistance (2): JIS for extruded insulated wire and bare copper wire
Twist two pieces in accordance with C3003,
After a heat treatment at 0 ° C. for 168 hours (7 days), the dielectric breakdown voltage was measured. The larger the value is, the better the heat resistance is. The ratio of the breakdown voltage after the degradation to the breakdown voltage before the degradation, that is, the residual ratio (%) of the breakdown voltage after the degradation is higher. If it is 50% or more, the IEC standard Pub. 172 heat resistance class E is generally satisfied. The tests for the solderability and the coefficient of static friction were performed in the same manner as in Example 3. Table 4 shows the results.

[0040]

[Table 4]

As is clear from the comparison between the results of Examples 19 to 21 and the results of Comparative Example 6, the insulated wire of the present invention was obtained by extruding a resin mixture of a polyethylene terephthalate resin and an ionomer, which is currently in practical use. Compared to two insulating layers coated with a nylon layer as the outermost layer, the solderability and coil workability are equal and the heat resistance is excellent.

[0042]

As is clear from the above description, the multilayer insulated wire of the present invention can be directly soldered at the time of terminal processing, and has a sufficient heat resistance level.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a transformer having a structure in which a three-layer insulated wire is wound.

FIG. 2 is a sectional view showing an example of a transformer having a conventional structure.

FIG. 3 is a schematic view showing a method for measuring a static friction coefficient.

[Explanation of symbols]

 Reference Signs List 1 ferrite core 2 bobbin 3 insulating barrier 4 primary winding 4a conductor 4b, 4c, 4d insulating layer 5 insulating tape 6 secondary winding 6a conductor 6b, 6c, 6d insulating layer 7 multilayer insulated wire 8 load plate 9 pulley 10 load

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI (C08L 79/08 69:00 67:00 77:00) (C08L 81/06 69:00 67:00 77:00)

Claims (10)

[Claims] 1. A multilayer insulated wire comprising a conductor and two or more solderable extruded insulation layers covering the conductor, wherein at least one of the insulation layers is a polyetherimide resin or a polyetherimide resin. 10 parts by weight of at least one resin (B) selected from a polycarbonate resin, a polyarylate resin, a polyester resin, and a polyamide resin with respect to 100 parts by weight of at least one resin (A) selected from an ether sulfone resin. A multilayer insulated wire characterized by being formed from the resin blend compounded above. 2. The multilayer insulated wire according to claim 1, wherein said resin (A) is a polyether sulfone resin. 3. The multilayer insulated wire according to claim 1, wherein said resin (B) is a polycarbonate resin. 4. The multilayer insulated wire according to claim 1, wherein said resin (A) is a polyether sulfone resin, and said resin (B) is a polycarbonate resin. 5. The multilayer insulated wire according to claim 1, wherein the resin (A) is a polyether sulfone resin having a repeating unit represented by the following formula. Embedded image (In the formula, n represents a positive integer.) 6. The resin mixture according to claim 1, wherein 10 to 70 parts by weight of the resin (B) is mixed with 100 parts by weight of the resin (A). 2. The multilayer insulated wire according to item 1. 7. The method according to claim 1, wherein the conductor is preheated to a temperature not exceeding 140 ° C. or the insulating layer is coated thereon without preheating. A multilayer insulated wire as described. 8. The insulating layer according to claim 1, wherein at least one of the insulating layers formed of the resin mixture is formed of a thermoplastic polyester resin or a polyamide resin. The multilayer insulated wire according to any one of the above. 9. The multilayer insulated wire according to claim 1, wherein the uppermost layer of the insulating layer is made of a polyamide resin. 10. A transformer using the multilayer insulated wire according to any one of claims 1 to 9.