JP5520468B2 - Multilayer insulated wire and transformer using the same - Google Patents

Description

  The present invention relates to a multilayer insulated wire having an insulating layer composed of three or more extruded coating layers and a transformer using the same.

The structure of the transformer is defined by IEC standard (International Electrotechnical Communication Standard) Pub. That is, in these standards, at least three insulating layers (the enamel film covering the conductor is not recognized as an insulating layer) are formed between the primary winding and the secondary winding in the winding or the insulation. The thickness of the layer is 0.4 mm or more, and the creepage distance between the primary winding and the secondary winding is 5 mm or more, and 3000 V is applied to the primary side and the secondary side, depending on the applied voltage. It is sometimes prescribed that it can withstand more than 1 minute.
Under such a standard, conventionally, a transformer occupying a mainstream seat has been employed in a structure as illustrated in a sectional view in FIG. In this transformer, an enamel-covered primary winding 4 is wound in a state in which insulation barriers 3 for securing a creeping distance are arranged at both ends of the peripheral surface of the bobbin 2 on the ferrite core 1. An insulating tape 5 is wound on at least three layers on the primary winding 4, and an insulating barrier 3 for securing a creepage distance is further disposed on the insulating tape, and then an enamel-coated secondary winding 6. Is a wound structure.

However, in recent years, a transformer having a structure not including the insulating barrier 3 or the insulating tape layer 5 as shown in FIG. 1 has been used in place of the transformer having the cross-sectional structure shown in FIG. . Compared with the transformer having the structure shown in FIG. 2, this transformer can be reduced in size as a whole, and has the advantage that the winding work of the insulating tape can be omitted.
When the transformer shown in FIG. 1 is manufactured, the primary winding 4 and the secondary winding 6 to be used have at least three insulating layers 4b (6b) on the outer periphery of one or both of the conductors 4a (6a). , 4c (6c), 4d (6d) are required in relation to the IEC standard.

  As such a winding, an insulating tape is wound around the outer periphery of the conductor to form a first insulating layer, and further an insulating tape is wound thereon to form a second insulating layer and a third layer. An insulating layer having a three-layer structure in which insulating layers are sequentially formed and delaminated from each other is known. In addition, it is also known that a fluororesin is sequentially extruded and coated on the outer periphery of a conductor instead of an insulating tape to form a total of three insulating layers (see, for example, Patent Document 1).

However, in the case of the above-described insulating tape winding, the winding work is unavoidable, so the productivity is remarkably low, and therefore the wire cost is very high.
Further, in the case of the above-mentioned fluororesin extrusion, the insulating layer is formed of a fluororesin, so that it has an advantage of good heat resistance, but the cost of the resin is high, and the resin is pulled at a high shear rate. And the appearance is deteriorated. For this reason, it is difficult to increase the production speed, and there is a problem that the cost of the electric wire becomes high as in the case of the insulating tape winding.

In order to solve these problems, a modified polyester resin which controls crystallization and suppresses a decrease in molecular weight as the first and second insulating layers is extruded on the outer periphery of the conductor, and a polyamide resin is used as the third insulating layer. Has been put to practical use (see, for example, Patent Documents 2 and 3).
However, when a polyamide resin is extrusion coated as the third insulating layer, the polyamide resin has a soft wire surface and is susceptible to scratches. Since it is used in electrical and electronic equipment, the tip of the component may be scratched, causing a failure. Therefore, there is a demand for a multilayer insulated wire that has sufficient elongation characteristics and is resistant to scratches on the surface of the wire.
Japanese Utility Model Publication No. 3-56112 US Pat. No. 5,606,152 JP-A-6-223634

  In order to solve the above problems, the present invention satisfies the heat resistance requirement, has sufficient elongation characteristics as an electric wire, and has good workability resistant to scratches due to the tip of a component required as a coil application. Another object of the present invention is to provide a multi-layer insulated wire that also has A further object of the present invention is to provide a transformer with excellent electrical characteristics and high reliability, which is formed by winding an insulated wire that has good heat resistance and good elongation characteristics and scratch resistance.

The above object of the present invention has been achieved by the following multilayer insulated wires and a transformer using the same.
That is, the present invention
(1) A multilayer insulated wire comprising a conductor and three or more extruded insulation layers covering the conductor,
The outermost layer (A) of the insulating layer is a thermoplastic polyester resin formed by condensation polymerization of an aliphatic alcohol component and an acid component, all or part of which has 4 carbon atoms. A resin in which the thermoplastic polyester resin contained in the outermost layer (A) is selected from polybutylene terephthalate resin, polybutylene naphthalate resin, and polybutylene terephthalate elastomer using a polybutylene terephthalate resin as a hard segment Consisting of an extrusion coating layer that is only
The innermost layer (B) consists of an extrusion coating layer containing a thermoplastic polyester resin formed by condensation polymerization of an aliphatic alcohol component and an acid component in whole or in part,
The insulating layer (C) between the outermost layer and the innermost layer contains a crystalline resin having a melting point of 250 ° C. or higher or an amorphous resin having a glass transition temperature of 180 ° C. or higher, and constitutes the insulating layer (C). A multilayer insulated wire characterized in that the resin comprises an extrusion coating layer which is a resin selected from a polyester resin, a polyphenylene sulfide resin, a polyethersulfone resin and a thermoplastic elastomer having an epoxy group;
(2) The resin forming the outermost layer (A) of the insulating layer is a thermoplastic polyester resin in which the number of carbon atoms of the aliphatic alcohol component is 4, or relative to 100 parts by mass of the thermoplastic polyester resin The multilayer insulated wire according to (1), which is a resin mixture obtained by blending 1 to 20 parts by mass of an epoxy group-containing thermoplastic elastomer,
(3) The multilayer insulated wire according to (1) or (2), wherein the thermoplastic polyester resin forming the outermost layer (A) of the insulating layer is a polybutylene terephthalate resin (PBT),
(4) The multilayer insulated wire according to (1) or (2), wherein the thermoplastic polyester resin forming the outermost layer (A) of the insulating layer is a polybutylene naphthalate resin (PBN),
(5) The multilayer insulated wire according to (1), wherein the resin forming the outermost layer (A) of the insulating layer is a polybutylene terephthalate elastomer using a polybutylene terephthalate resin (PBT) as a hard segment. ,
(6) The multilayer insulated wire according to (1), wherein the thermoplastic polyester resin forming the innermost layer (B) of the insulating layer is a polybutylene terephthalate resin (PBT),
(7) The multilayer insulated wire according to (1), wherein the thermoplastic polyester resin forming the innermost layer (B) of the insulating layer is a polyethylene terephthalate resin (PET),
(8) The resin forming the innermost layer (B) of the insulating layer is 100 parts by mass of a thermoplastic polyester resin formed by condensation polymerization of an aliphatic alcohol component and an acid component in whole or in part. A multilayered insulated wire according to (1), (6) or (7), which is a resin blend comprising 1 to 20 parts by mass of an epoxy group-containing thermoplastic elastomer,
(9) The crystalline resin forming the insulating layer (C) is a polyester resin composition containing 75 to 95 parts by mass of a polyester resin other than liquid crystal polyester and 5 to 25 parts by mass of liquid crystal polyester. The multilayer insulated wire according to (1),
(10) The crystalline resin forming the insulating layer (C) is a resin mixture obtained by blending 1 to 20 parts by mass of an epoxy group-containing thermoplastic elastomer with respect to 100 parts by mass of the polyester resin composition. (9) the multilayer insulated wire according to (9),
(11) The multilayer insulated wire according to (1), wherein the crystalline resin forming the insulating layer (C) is polyphenylene sulfide resin (PPS),
(12) The multilayer resin wire according to (1), wherein the amorphous resin forming the insulating layer (C) is a polyethersulfone resin (PES), and
(13) A transformer comprising the multilayer insulated wire according to any one of (1) to (12),
Is to provide.

  The multilayer insulated wire of the present invention sufficiently satisfies the heat resistance level, is excellent in elongation characteristics, and is resistant to scratches due to the tip of parts required for coil applications, thus improving workability during winding processing. Is. Up to now, electric wires that have the heat resistance of heat-resistant class E have been a concern because they use polyamide resin and are vulnerable to scratches. In the multilayer insulated wire of the present invention, as the insulating layer, the outermost layer is not only excellent in chemical resistance, but also has a specific polyester resin that is excellent in elongation characteristics and resistant to scratches, in the insulating layers other than the outermost layer and the innermost layer. Satisfies the above requirements by using a heat-resistant crystalline resin having a specific melting point or higher or an amorphous resin having a specific glass transition temperature or higher in combination with a polyester resin having adhesiveness to the conductor in the innermost layer. I was able to. Since the multilayer insulated wire is excellent in heat resistance, it can be directly soldered during terminal processing, and the workability of winding processing is sufficiently enhanced. Furthermore, the transformer of the present invention using the multilayer insulated wire has excellent electrical characteristics and high reliability.

First, the resin constituting each layer of the multilayer insulated wire of the present invention will be described.
For the outermost layer (A) of the insulated wire, a thermoplastic polyester resin is used because it requires a resin having excellent solvent resistance, excellent elongation characteristics, and high film strength. This thermoplastic polyester resin is a thermoplastic polyester resin formed by condensation polymerization of an aliphatic alcohol component and an acid component, all or part of which is a resin having 4 carbon atoms in the aliphatic alcohol component. . In general, polyester resin, which is a crystalline resin, is said to have excellent solvent resistance, but when used as an electric wire film, it does not progress in crystallization and is in an amorphous state, so it is affected by the solvent. End up. However, among the polyester resins, the resin whose aliphatic alcohol component has 4 carbon elements has a high crystallization speed, and when used as a wire film, the crystallization proceeds quickly, so that the solvent resistance is excellent. Furthermore, it was found that the wire film strength was improved due to crystallization.

  In a preferred embodiment of the present invention, the outermost layer (A) is an extrusion coating layer containing a thermoplastic polyester resin formed by condensation polymerization of an aliphatic alcohol component and an acid component in whole or in part. And the resin whose carbon atom number of the aliphatic alcohol component is 4, for example, polybutylene terephthalate resin (PBT), polybutylene naphthalate resin (PBN), PBT using polybutylene terephthalate resin (PBT) as a hard segment A typical example is an elastomer.

  Examples of the aromatic dicarboxylic acid used in the synthesis of the thermoplastic polyester resin include terephthalic acid, isophthalic acid, terephthaldicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenoxyethanedicarboxylic acid, diphenyl ether carboxylic acid, methyl terephthalic acid, and methyl isophthalic acid. Etc. Of these, terephthalic acid is particularly preferred.

  A part of the aromatic dicarboxylic acid can be substituted with an aliphatic dicarboxylic acid. Examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, sebacic acid and the like. The substitution amount of these aliphatic dicarboxylic acids is preferably less than 30 mol%, and particularly preferably less than 20 mol% of the aromatic dicarboxylic acid. On the other hand, the alcohol component used in the ester reaction is preferably an aliphatic diol, such as butylene glycol.

  In the present invention, as commercially available resins that can be preferably used as the outermost layer (A), polybutylene terephthalate (PBT) resins include “Novaduran” (trade name: manufactured by Mitsubishi Engineering), “Ultradura” (tradename). : BASF Japan), polybutylene naphthalate (PBN) resin, “Vylopet” (trade name: manufactured by Toyobo), “Teijin PBN” (trade name: manufactured by Teijin) and the like. Examples of the PBT elastomer include “Perprene” (trade name: manufactured by Toyobo Co., Ltd.) and “Hytrel” (trade name: manufactured by Toray DuPont).

The innermost layer (B) of the insulated wire requires a resin having excellent elongation characteristics as a wire coating material and excellent adhesion to the conductor, and is preferably a thermoplastic polyester resin.
As this polyester resin used in the present invention, those obtained by ester reaction of an aromatic dicarboxylic acid or a dicarboxylic acid in which a part thereof is substituted with an aliphatic dicarboxylic acid and an aliphatic diol are preferably used. For example, polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polyethylene naphthalate resin (PEN), polycyclohexanedimethylene terephthalate (PCT) resin, and the like can be given as representative examples.

  An aromatic dicarboxylic acid is preferable as an acid component used in the synthesis of the polyester resin. For example, terephthalic acid, isophthalic acid, terephthaldicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenoxyethanedicarboxylic acid, diphenyl ether carboxylic acid, methyl terephthalic acid, methyl Examples thereof include isophthalic acid. Of these, terephthalic acid is particularly preferred.

A part of the aromatic dicarboxylic acid may be substituted with an aliphatic dicarboxylic acid, and examples thereof include succinic acid, adipic acid, and sebacic acid. The substitution amount of these aliphatic dicarboxylic acids is preferably less than 30 mol%, and particularly preferably less than 20 mol% of the aromatic dicarboxylic acid.
On the other hand, the alcohol component used in the ester reaction is preferably an aliphatic diol, and examples thereof include ethylene glycol, trimethylene glycol, tetramethylene glycol, hexanediol, and decanediol. Of these, ethylene glycol and tetramethyl glycol are preferred. Moreover, as aliphatic diol, the one part may become oxyglycol like polyethyleneglycol or polytetramethyleneglycol.

In the present invention, as a commercially available resin that can be preferably used as the innermost layer (B), polyethylene terephthalate (PET) resin includes “Vylopet” (trade name: manufactured by Toyobo Co., Ltd.), “Belpet” (trade name: Kanebo). And Teijin PET) (trade name: manufactured by Teijin Limited).
Examples of the polyethylene naphthalate (PEN) resin include “Teijin PEN” (trade name: manufactured by Teijin Limited), and examples of the polycyclohexanedimethylene terephthalate (PCT) resin include “Ecter” (trade name: manufactured by Toray Industries, Inc.). It is done.

In the present invention, the polyester resin used for the outermost layer (A) and the innermost layer (B) may be alone, but at least selected from the group consisting of an epoxy group, an oxazolyl group, an amino group and a maleic anhydride residue. It is also preferable to contain a reactive modified resin having one type of functional group for improving the flexibility of the electric wire.
The above functional group is a functional group having reactivity with the polyester resin, and by mixing and mixing with the polyester resin, both react to become a resin mixture. As the resin having this reactivity, an epoxy group is particularly preferable. When the epoxy group is ring-opened, the reaction proceeds with chemical bonding with the polyester resin. The reactive modified resin having the above functional group preferably has 20% by mass or less, more preferably 15% by mass or less, of the functional group-containing monomer component. Such a resin is preferably a copolymer containing an epoxy group-containing compound component. As an epoxy group containing compound which gives the polymer which has reactivity, the glycidyl ester compound of unsaturated carboxylic acid shown by following General formula (1) is mentioned, for example.

[Wherein, R represents an alkenyl group having 2 to 18 carbon atoms, and X represents a carbonyloxy group. ]

  Specific examples of the unsaturated carboxylic acid glycidyl ester include glycidyl acrylate, glycidyl methacrylate, itaconic acid glycidyl ester, etc. Among them, glycidyl methacrylate is preferable.

  As a typical example of the reactive modified resin having reactivity with the above-described polyester resin, commercially available resins include, for example, “Bond First” (trade name: manufactured by Sumitomo Chemical Co., Ltd.), “Rotada” (trade name: Atofina).

In a preferred embodiment, all or part of the outermost layer (A) or the innermost layer (B) is formed by condensation polymerization of an aliphatic alcohol component and an acid component with respect to 100 parts by mass of a thermoplastic polyester resin. 1 to 20 parts by mass of a reactive modifying resin containing at least one functional group selected from the group consisting of an epoxy group, an oxazolyl group, an amino group, and a maleic anhydride residue. When the compounding amount of the reactive modifying resin is too large, the heat resistance of the insulating layer is remarkably lowered, and when it is too small, the effect of improving the flexibility is not exhibited.
The more preferable mixture ratio of both is 1-15 mass parts with respect to 100 mass parts of the former.

The insulating layer (C) between the outermost layer and the innermost layer of the insulated wire of the present invention is an extrusion coating containing a heat-resistant crystalline resin having a melting point of 250 ° C. or higher or an amorphous resin having a glass transition temperature of 180 ° C. or higher. Is a layer.
As the crystalline resin having a melting point of 250 ° C. or higher of the insulating layer (C) of the present invention, a polyester resin containing a liquid crystal polyester is preferably used, and a polyester resin (for example, a liquid crystal polyester blended with a polyester resin other than the liquid crystal polyester). “Teijin PET” (trade name: manufactured by Teijin Ltd.) and “Unitika Rod Run” (trade name: manufactured by Unitika Ltd.)) are also preferable.

The liquid crystal polyester used for the insulating layer (C) between the outermost layer and the innermost layer is not particularly limited in terms of molecular structure, density, molecular weight, etc., and preferably has a melting point of 250 ° C. or higher, which forms a liquid crystal when melted. Is preferably a molten liquid crystalline polyester (thermotropic liquid crystalline polyester) having a melting point of 280 ° C. or higher and at most about 350 ° C., and the molten liquid crystalline polyester is preferably a molten liquid crystalline polyester copolymer.
If the melting point of the liquid crystal polyester is too low, a desired heat resistance effect cannot be obtained as an electric wire, which is not preferable.

  Such molten liquid crystal polyester includes (I) a copolymer type polyester of rigid linear components obtained by block copolymerization of two types of rigid linear polyesters having different lengths, and (II) rigid linearity. Non-linear structure-introduced polyester obtained by block copolymerization of polyester and rigid non-linear polyester, (III) Introduced flex chain by copolymerization of rigid linear polyester and flexible polyester (IV) A nucleus-substituted aromatic-introduced polyester in which a substituent is introduced onto the aromatic ring of a rigid linear and linear polyester.

  Examples of the repeating unit of such polyester include the following a. Derived from an aromatic dicarboxylic acid, b. Derived from an aromatic diol, c. Although what originates in aromatic hydroxycarboxylic acid can be mentioned, it is not limited to these.

a. Repeating units derived from aromatic dicarboxylic acids:

b. Repeating units derived from aromatic diols:

c. Repeating units derived from aromatic hydroxycarboxylic acids:

  From the balance of operability, heat resistance, mechanical properties of the insulating film, etc. in the coating forming process of the coating layer, the liquid crystalline polyester employed in the present invention preferably contains the following repeating unit, more preferably this repeating unit. It contains at least 30 mol% of the whole.

  Preferred combinations of repeating units include combinations of repeating units described in the following (I) to (VI).

The method for producing such a liquid crystal polyester is described in, for example, JP-A-2-51523, JP-B-63-3888, JP-B-63-3891 and the like.
Among these, the combinations shown in (I), (II) and (V) are preferable, and the combination shown in (V) is more preferable.

  Liquid crystalline polyester has a fluidization temperature of 300 ° C. or higher, and the viscosity at the time of melting is lower than that of polyethylene terephthalate and 6,6 nylon, which are conventionally used. With this, a film-like insulating layer can be formed.

  On the other hand, the liquid crystal polyester film has an extremely low elongation of several percent and has a problem in flexibility. Therefore, by adding a polyester resin such as polybutylene terephthalate, polyethylene terephthalate, or polyethylene naphthalate to the liquid crystal polyester, the elongation of the film can be improved and the flexibility can be improved.

In the present invention, the liquid crystal polyester-containing resin forming the insulating layer (C) is 75 to 95 parts by mass (preferably 80 to 90) of a polyester resin other than the liquid crystal polyester and 5 to 25 parts by mass of the liquid crystal polyester (preferably 10 to 10 parts). What contains 20 mass parts) is preferable. If the content of the liquid crystal polyester is too small, a desired heat resistance effect cannot be obtained, and if it is too large, the elongation characteristics are lowered and the flexibility as an electric wire cannot be maintained.
Moreover, arbitrary methods can be used for the mixing method of polyester resins other than liquid crystal polyester, and liquid crystal polyester.

In the present invention, the polyester resin composition comprising the liquid crystal polyester and other than the liquid crystal polyester includes a reactive modifying resin (thermoplastic elastomer) for improving the flexibility of the electric wire, and the polyester resin is used as a continuous layer. Further, it may be a mixture of a resin dispersion having a reactive modified resin as a dispersed phase. The content of the reactive modified resin in the present invention is preferably 1 to 20 parts by mass, and more preferably 4 to 13 parts by mass with respect to 100 parts by mass of the polyester resin.
When the amount of the reactive modified resin exceeds 20 parts by mass, the heat resistance is slightly lowered, and when the amount is too small, the effect of improving the flexibility is not exhibited. It is presumed that the heat resistance of the elastomer component is lower than that of liquid crystal polyester and polyester resins other than liquid crystal polyester.
The reactive modified resin used may be the same as the reactive modified resin used for the outermost layer (A) and the innermost layer (B).

  In addition, for the insulating layer (C) between the outermost layer and the innermost layer of the insulated wire of the present invention, a crystalline resin having a melting point other than those described above can be 250 ° C. or higher. For example, polyphenylene sulfide resin (PPS) having a melting point of 280 ° C. (for example, “DICCPPS FZ2200A8” (trade name: manufactured by Dainippon Ink & Chemicals, Inc.) is used as a coating layer for multilayer insulated wires. A polyphenylene sulfide resin having a low degree of cross-linking capable of obtaining extrudability is preferable, however, a cross-linking polyphenylene sulfide resin may be combined or a cross-linking component or a branching component may be contained inside the polymer as long as the resin characteristics are not impaired. Is possible.

  The polyphenylene sulfide resin having a low degree of cross-linking preferably has an initial tan δ (loss elastic modulus / storage elastic modulus) value of 1.5 or more in nitrogen at 1 rad / s and 300 ° C., and most preferably 2 or more. Resin. Although the upper limit is not particularly limited, the value of tan δ is 400 or less, but may be larger than this. The tan δ of the resin used in the present invention can be easily evaluated from the time-dependent measurement of the loss elastic modulus and storage elastic modulus in nitrogen at the above-described constant frequency and constant temperature, and particularly the initial loss elastic modulus immediately after the start of measurement and It is calculated from the storage elastic modulus. For the measurement, a sample having a diameter of 24 mm and a thickness of 1 mm is used. As an example of an apparatus capable of performing these measurements, there is an “ARES” (Advanced Rheometric Expansion System, product name) apparatus manufactured by TA Instruments Japan. The tan δ is a measure of the crosslinking level, and with a polyphenylene sulfide resin having a tan δ of less than 1.5, it is difficult to obtain sufficient flexibility and it is difficult to obtain a good appearance.

  Further, an amorphous resin having a glass transition temperature of 180 ° C. or higher can be used for the insulating layer (C) between the outermost layer and the innermost layer of the insulated wire of the present invention. For example, polyether sulfone resin (PES) (for example, “Sumika Excel PES4100” (trade name: manufactured by Sumitomo Chemical Co., Ltd.)) having a glass transition temperature of 225 ° C. can be mentioned.

  As the polyethersulfone resin, those represented by the following general formula (2) are preferably used.

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

(R ₃ represents an alkylene group such as —C (CH ₃ ) ₂ — or —CH ₂ —), and the group of R ₂ may further have a substituent. ). n represents a positive integer. ]

  The method for producing this resin is known per se, and an example thereof is a method for producing dichlorodiphenylsulfone, bisphenol S and potassium carbonate by reacting them in a high boiling point solvent. Commercially available resins include “Sumika Excel PES” (trade name: manufactured by Sumitomo Chemical Co., Ltd.), “Radel A”, “Radel R” (trade name: manufactured by Amoco), and the like.

Additives, inorganic fillers, processing aids, colorants, etc. that are usually used for other heat-resistant resins are added to the resin constituting each insulating layer in the present invention as long as the required characteristics are not impaired. Can do.
The multilayer insulating layer of the present invention is not limited to the above-described three layers, and an insulating layer made of liquid crystal polyester, polyphenylene sulfide, polyether sulfone, or the like can be provided as an intermediate layer for further improvement of heat resistance.

  As a conductor used in the present invention, a bare metal wire (single wire), an insulated wire provided with an enamel coating layer or a thin insulation layer on the bare metal wire, or 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. Further, when the number of core wires (element wires) is large (for example, 19-, 37-element wires), it may not be a stranded wire. When not a stranded wire, for example, a plurality of strands may be simply bundled substantially in parallel, or the bundle may be twisted at a very large pitch. In any case, it is preferable that the cross section is substantially circular.

  In the multilayer insulated wire of the present invention, a first insulating layer having a desired thickness is extruded and coated on the outer periphery of the conductor, and then a second layer having a desired thickness is formed on the outer periphery of the first insulating layer. It is manufactured by sequentially extruding and covering the insulating layers by a method of extrusion coating the insulating layers. The total thickness of the extruded insulating layer formed in this way is preferably in the range of 60 to 180 μm for the three layers. This is because if the overall thickness of the insulating layer is too thin, the resulting heat-resistant multilayer insulated wire has a large decrease in electrical characteristics, which may be unsuitable for practical use. Conversely, if it is too thick, it is not suitable for miniaturization. This is because processing may become difficult. A more preferable range is 70 to 150 μm. In addition, the thickness of each of the three layers is preferably 20 to 60 μm.

  As an embodiment of the present invention of a transformer using the above-mentioned multilayer insulated wire, the primary winding is not incorporated in the bobbin 2 on the ferrite core 1 as shown in FIG. 1 without incorporating an insulation barrier or an insulation tape layer. A structure in which the fourth and secondary windings 6 are formed is preferable. The multilayer insulated wire of the present invention can also be applied to other types of transformers.

EXAMPLES Next, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these.
(Examples 1-10 and Comparative Examples 1-4)
An annealed copper wire having a wire diameter of 1.0 mm was prepared as a conductor. Each resin shown in Table 1 is a resin for extrusion coating of each layer in the indicated ratio (the numerical value of the composition indicates part by mass), and the innermost layer (B) and the layer between the outermost layer and the innermost layer in order on the conductor ( C) and the outermost layer (A) were sequentially extruded and coated to produce a multilayer insulated wire with the indicated thickness (all 100 μm).

Each resin in Table 1 is as follows.
PBT resin: “Novaduran” (trade name: manufactured by Mitsubishi Engineering),
Polybutylene terephthalate resin PBN resin: “Vilopet” (trade name: manufactured by Toyobo Co., Ltd.), Polybutylene naphthalate resin reactive modified resin: “Bond First 7M” (trade name: manufactured by Sumitomo Chemical Co., Ltd.),
Epoxy group-containing resin PBT elastomer: “Perprene” (trade name: manufactured by Toyobo Co., Ltd.)
Polyester elastomer resin polyamide resin: “FDK-1” (trade name: manufactured by Unitika), polyamide 66 resin LCP resin: “Rod Run” (trade name: manufactured by Unitika), liquid crystal polyester resin PET resin: “Teijin PET” (product) Name: manufactured by Teijin Limited), polyethylene terephthalate resin PES resin: “Sumika Excel” (trade name: manufactured by Sumitomo Chemical Co., Ltd.), polyethersulfone resin PPS resin: “DICPPS” (trade name: manufactured by DIC), polyphenylene sulfide resin

About the obtained multilayer insulated wire, various characteristics were tested by the following specifications. The appearance was observed with the naked eye. The results obtained are shown in Table 1.
A. Check the degree of scratches on the wire surface:
JIS C 3003-1984 14 Solvent resistance (1) Simulates the method described in (1), and when the surface of the electric wire is rubbed once with a toe, it is visually inspected whether the coating is peeled off as the conductor appears.
Those where even a slight peeling was observed were indicated as “film peeling”, and those with no peeling were indicated as “good”.
B. Electrical heat resistance:
Evaluation was performed by the following test method in accordance with Annex U (electric wire) in 2.9.4.4 section of IEC standard 60950 and Annex C (transformer) in section 1.5.3.
A multi-layer insulated wire is wound around a mandrel with a diameter of 10 mm for 10 turns while applying a load of 118 MPa (12 kg / mm ² ), heated at 215 ° C. for 1 hour, further heated at 140 ° C. for 21 hours and 190 ° C. for 3 hours, and further 30 If it hold | maintains in the atmosphere of 95 degreeC and humidity for 48 hours, after that, if a voltage is applied for 1 minute at 3000V and it does not short-circuit, it determined with E class passing.
Similarly, it is wound around a mandrel, heated at 225 ° C. for 1 hour, further heated at 150 ° C. for 21 hours and 200 ° C. for 3 hours for 3 cycles, further maintained at 30 ° C. and 95% humidity for 48 hours, and then at 3000 V for 1 minute. If it is applied and no short circuit occurs, it is determined that Class B is acceptable.
(In either case, the evaluation is evaluated at n = 5, and even if one becomes NG, it is rejected).
C. Solvent resistance Wire wound 20 times the conductor diameter as a winding process is immersed in xylene, styrene, and isopropyl alcohol solvent for 30 seconds, dried and observed on the sample surface to determine whether crazing has occurred. It was. Since no crazing was observed in all the samples, “◯” was displayed.
Then, by combining the test results of A, B, and C, the pass / fail as an insulated wire was determined. The preferable one was “◯” and the inappropriate one was “×”.

From the results shown in Table 1, the following became clear.
In Comparative Examples 1 and 2 in which the outermost layer (A) was coated with the polyamide resin, the film peeled off as the conductor appeared as a result of the scratch test. In Comparative Examples 3 and 4, the layer (C) between the outermost layer and the innermost layer was PBT resin, but this had a melting point of about 224 ° C. and was outside the specified range of the present invention, and the electrical heat resistance was E type. I was not satisfied. On the other hand, in Examples 1-6, all of the scratch test, electrical heat resistance (type E), and solvent resistance satisfied the acceptance criteria. In Examples 7 to 10, the electrical heat resistance (type B) was satisfied.

FIG. 1 is a cross-sectional view showing a transformer having a structure in which a three-layer insulated wire is a winding in one embodiment of the present invention. FIG. 2 is a sectional view showing an example of a transformer having a conventional structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ferrite core 2 Bobbin 3 Insulation barrier 4 Primary winding 4a Conductors 4b, 4c, 4d Insulating layer 5 Insulating tape 6 Secondary winding 6a Conductors 6b, 6c, 6d Insulating layer

Claims (13)

A multilayer insulated wire comprising a conductor and three or more extruded insulation layers covering the conductor,
The outermost layer (A) of the insulating layer is a thermoplastic polyester resin formed by condensation polymerization of an aliphatic alcohol component and an acid component, all or part of which has 4 carbon atoms. A resin in which the thermoplastic polyester resin contained in the outermost layer (A) is selected from polybutylene terephthalate resin, polybutylene naphthalate resin, and polybutylene terephthalate elastomer using a polybutylene terephthalate resin as a hard segment Consisting of an extrusion coating layer that is only
The innermost layer (B) consists of an extrusion coating layer containing a thermoplastic polyester resin formed by condensation polymerization of an aliphatic alcohol component and an acid component in whole or in part,
The insulating layer (C) between the outermost layer and the innermost layer contains a crystalline resin having a melting point of 250 ° C. or higher or an amorphous resin having a glass transition temperature of 180 ° C. or higher, and constitutes the insulating layer (C). A multi-layer insulated electric wire characterized in that the resin comprises an extrusion coating layer which is a resin selected from a polyester resin, a polyphenylene sulfide resin, a polyether sulfone resin, and a thermoplastic elastomer having an epoxy group.   The resin that forms the outermost layer (A) of the insulating layer is a thermoplastic polyester resin in which all aliphatic alcohol components have 4 carbon atoms, or an epoxy with respect to 100 parts by mass of the thermoplastic polyester resin. The multilayer insulated wire according to claim 1, which is a resin mixture obtained by blending 1 to 20 parts by mass of a thermoplastic elastomer having a group.   The multilayer insulated wire according to claim 1 or 2, wherein the thermoplastic polyester resin forming the outermost layer (A) of the insulating layer is a polybutylene terephthalate resin.   The multilayer insulated wire according to claim 1 or 2, wherein the thermoplastic polyester resin forming the outermost layer (A) of the insulating layer is a polybutylene naphthalate resin. 2. The multilayer insulated wire according to claim 1, wherein the resin forming the outermost layer (A) of the insulating layer is a polybutylene terephthalate elastomer using a polybutylene terephthalate resin as a hard segment.   The multilayer insulated wire according to claim 1, wherein the thermoplastic polyester resin forming the innermost layer (B) of the insulating layer is a polybutylene terephthalate resin.   The multilayer insulated wire according to claim 1, wherein the thermoplastic polyester resin forming the innermost layer (B) of the insulating layer is a polyethylene terephthalate resin.   The resin forming the innermost layer (B) of the insulating layer has an epoxy group with respect to 100 parts by mass of a thermoplastic polyester resin formed by condensation polymerization of an aliphatic alcohol component and an acid component, in whole or in part. The multilayer insulated wire according to claim 1, 6 or 7, which is a resin mixture obtained by blending 1 to 20 parts by mass of a thermoplastic elastomer.   The crystalline resin forming the insulating layer (C) is a polyester resin composition containing 75 to 95 parts by mass of a polyester resin other than liquid crystal polyester and 5 to 25 parts by mass of liquid crystal polyester. The multilayer insulated wire according to 1.   The crystalline resin forming the insulating layer (C) is a resin blend obtained by blending 1 to 20 parts by mass of an epoxy group-containing thermoplastic elastomer with respect to 100 parts by mass of the polyester resin composition. The multilayer insulated wire according to claim 9,   The multilayer insulated wire according to claim 1, wherein the crystalline resin forming the insulating layer (C) is a polyphenylene sulfide resin.   The multilayer insulated wire according to claim 1, wherein the amorphous resin forming the insulating layer (C) is a polyethersulfone resin. A transformer comprising the multilayer insulated wire according to any one of claims 1 to 12.

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