HK1172144A - Multilayer insulated wire and transformer using same - Google Patents

Description

Multilayer insulated wire and transformer using the same

Technical Field

The present invention relates to a multilayer insulated wire having an insulating layer comprising 3 or more extruded coating layers, and a transformer using the same.

Background

The structure of the transformer is defined by IEC Standard (International electrotechnical commission Standard) pub.60950 and the like. Namely, the following are specified in these standards: in the winding wire, at least 3 layers of insulating layers (varnish of the covered conductor is not considered to be an insulating layer) are formed between the primary winding wire and the secondary winding wire, or the thickness of the insulating layers is 0.4mm or more. The creepage distance between the primary winding wire and the secondary winding wire is different depending on the applied voltage, but is considered to be 5mm or more. Furthermore, provision is made for: the voltage of 3000V is applied to the primary side and the secondary side, and the voltage can endure for more than 1 minute; and so on.

Based on such a standard, conventionally, a transformer which occupies the mainstream has a structure as exemplified by a sectional view in fig. 2. The transformer has the following structure: an insulation barrier 3 for securing a creepage distance is arranged at both side ends of the circumferential surface of the bobbin 2 on the ferrite core 1, an enameled primary winding wire 4 is wound in this state, then an insulation tape 5 of at least 3 layers is wound on the primary winding wire 4, an insulation barrier 3 for securing a creepage distance is further arranged on the insulation tape, and then an enameled secondary winding wire 6 is wound in the same manner.

In recent years, however, a transformer having a structure not including the insulating barrier 3 and the insulating tape layer 5 as shown in fig. 1 has been used instead of the transformer (transformer) having the cross-sectional structure shown in fig. 2. Compared with the transformer with the structure of fig. 2, the transformer has the advantages that the whole transformer can be miniaturized, the winding operation of the insulating tape can be omitted, and the like.

In the case of manufacturing the transformer shown in fig. 1, it is necessary to form at least 3 insulating layers 4b (6b), 4c (6c), 4d (6d) on the outer periphery of the conductor 4a (6a) of either or both of the 1-time winding wire 4 and the 2-time winding wire 6 used, in view of the relationship with the IEC standard described above.

As such a winding wire, a winding wire is known in which an insulating tape is wound around the outer periphery of a conductor to form a 1 st insulating layer, and further, an insulating tape is wound around the insulating tape to form a 2 nd insulating layer and a 3 rd insulating layer in this order, thereby forming insulating layers having a 3-layer structure in which layers are separated from each other. Further, there is also known a winding wire in which a fluororesin is sequentially extruded on the outer periphery of a conductor without using an insulating tape, and 3 insulating layers are formed as a whole (for example, see patent document 1).

However, in the case of manufacturing a winding wire by winding the insulating tape, since a winding work is inevitable, productivity is remarkably reduced, and thus the cost of the electric wire is very high.

In addition, the insulated wire extrusion-coated with the fluororesin has an advantage of excellent heat resistance because the insulating layer is formed of a fluororesin. However, since the fluororesin is expensive and has a property of deteriorating the appearance state when it is stretched at a high shear rate, it is difficult to increase the production rate. Therefore, the insulated wire extrusion-coated with the fluororesin has a problem of high wire cost as in the case of the insulating tape roll.

In order to solve these problems, a multilayer insulated wire in which a modified polyester resin whose crystallization is controlled and whose molecular weight reduction is suppressed is extruded as a 1 st and a 2 nd insulating layers on the outer periphery of a conductor is practically used; a coated polyamide resin is extruded as a 3 rd insulating layer (for example, see patent documents 2 and 3). Further, with the recent miniaturization of electric and electronic devices, there is a concern that heat generation may affect the devices, and as a multilayer insulated wire having further improved heat resistance, there has been proposed a multilayer insulated wire in which a polyethersulfone resin is extrusion-coated on an inner layer and a polyamide resin is extrusion-coated on an outermost layer (see, for example, patent document 4).

The insulated wire described above has been developed for use in electric/electronic machine applications in compliance with IEC Standard (international electrotechnical commission Standard)) pub.60950. It is also desired that an insulated wire that can be made compact and highly efficient be used for home appliances conforming to IEC standard pub.61558. Accordingly, a multilayer insulated wire conforming to IEC standard pub.61558, which is more stringent in the required voltage regulations, is sought.

Documents of the prior art

Patent document

Patent document 1: japanese Kokai publication Hei-3-56112

Patent document 2: specification of U.S. Pat. No. 5,606,152

Patent document 3: japanese laid-open patent publication No. 6-223634

Patent document 4: japanese laid-open patent publication No. 10-134642

Disclosure of Invention

Accordingly, an object of the present invention is to provide a multilayer insulated wire that satisfies IEC standard pub.61558, which is a more stringent voltage regulation requirement as described above. Another object of the present invention is to provide a highly reliable transformer formed by winding such an insulated wire having excellent withstand voltage characteristics.

That is, the present invention provides the following technical means.

(1) A multilayer insulated wire comprising a conductor and at least 3 extruded insulating layers covering the conductor, wherein the outermost layer (A) of the insulating layers is formed of an extruded coating layer of a polyamide resin and has a film thickness of 25 μm or less, and the inner layer (B) (i.e., the inner layer) of the insulating layers is formed of an extruded coating layer containing a crystalline resin having a melting point of 225 ℃ or higher or an amorphous resin having a glass transition temperature of 200 ℃ or higher;

(2) the multilayer insulated wire according to (1), wherein the resin forming the inner layer (B) of the insulating layer contains a crystalline resin having a melting point of 225 ℃ or higher, the crystalline resin being a thermoplastic linear polyester resin;

(3) the multilayer insulated wire according to (1) or (2), wherein the resin forming the inner layer (B) of the insulating layer contains a resin mixture obtained by blending 5 to 40 parts by mass of a vinyl copolymer having a carboxylic acid or a metal salt of a carboxylic acid in a side chain with 100 parts by mass of a crystalline resin having a melting point of 225 ℃ or higher, the crystalline resin being a thermoplastic linear polyester resin;

(4) the multilayer insulated wire according to (1) or (2), wherein the resin forming the inner layer (B) of the insulating layer contains a resin mixture obtained by blending 1 to 20 parts by mass of a resin having an epoxy group with 100 parts by mass of a crystalline resin having a melting point of 225 ℃ or higher, the crystalline resin being a thermoplastic linear polyester resin;

(5) the multilayer insulated wire according to (1), wherein the base resin component forming the inner layer (B) of the insulating layer is composed of 75 to 95 mass% of a crystalline resin having a melting point of 225 ℃ or higher, which is a polyester-based resin, and 5 to 25 mass% of a liquid crystal polymer having a melting point of 225 ℃ or higher, which is a polyester-based resin, excluding the liquid crystal polymer;

(6) the multilayer insulated wire according to (5), wherein the resin forming the inner layer (B) of the insulating layer contains 1 to 20 parts by mass of a resin having an epoxy group per 100 parts by mass of the base resin component;

(7) the multilayer insulated wire according to (1), wherein the resin forming the inner layer (B) of the insulating layer contains a crystalline resin having a melting point of 225 ℃ or higher, the crystalline resin being a polyphenylene sulfide resin;

(8) the multilayer insulated wire according to (1), wherein the resin forming the inner layer (B) of the insulating layer contains an amorphous resin having a glass transition temperature of 200 ℃ or higher, the amorphous resin being a polyether sulfone resin;

(9) the multilayer insulated wire according to (1), characterized in that the inner layer (B1) in contact with the outermost layer (A) of the insulating layer is a crystalline resin having a melting point of 225 ℃ or higher, the crystalline resin is a polyphenylene sulfide resin, at least 1 layer of the inner layers (B2) other than the inner layer (B1) contains 1 to 20 parts by mass of a resin having an epoxy group per 100 parts by mass of a crystalline resin having a melting point of 225 ℃ or higher, the crystalline resin is a thermoplastic linear polyester resin; and

(10) a transformer formed using the multilayer insulated wire according to any one of (1) to (9).

The above object of the present invention is achieved by a multilayer insulated wire and a transformer using the same, which are described below.

The multilayer insulated wire not only maintains more than B heat-resistant grades, but also has the voltage-resistant characteristic of IEC standard Pub.61558 meeting the requirements of household appliances. The heat resistance of B or more heat resistance grades means that the test method of IEC standard Pub.61558 is followed, that is, "winding a multilayer insulated wire 10 turns around a mandrel having a diameter of 1.0mm while applying a load of 9.4kg, heating at 225 ℃ for 1 hour, further performing 3 times of cyclic heating of heating at 150 ℃ for 21 hours and heating at 200 ℃ for 3 hours, further keeping the temperature in an atmosphere of 30 ℃ and 95% humidity for 48 hours, and thereafter applying a voltage of 5500V for 1 minute without short circuit". In the multilayer insulated wire of the present invention, the outermost layer is made of a polyamide resin, and the inner layer is made of a resin having excellent stretching properties and heat resistance required for the wire. In particular, when the outermost layer is made of a polyamide resin, the thickness of the outermost layer is made thin to some extent, which further improves the withstand voltage characteristics, and thus the diameter of the insulated wire can be reduced.

The multilayer insulated wire of the present invention can be directly welded at the end processing, and the workability of winding wire processing is sufficiently improved. The transformer of the present invention formed using the multilayer insulated wire has excellent electrical characteristics at high voltage and high temperature heating, and high reliability.

The above and other features and advantages of the present invention will be made apparent from the following description with reference to the accompanying drawings, where appropriate.

Drawings

Fig. 1 is a sectional view showing an example of a transformer in which a structure of a multilayer insulated wire is made into a winding wire.

Fig. 2 is a sectional view showing an example 1 of a transformer having a conventional structure.

Fig. 3 is a sectional view of a multilayer insulated wire in which the insulating layer is composed of 3 layers.

Detailed Description

Although insulated wires have been used in the field of electric/electronic appliances, multilayer insulated wires in the field of household electric appliances, which have higher required levels of withstand voltage, are still required. However, among the multilayer insulated wires so far, there is no insulated wire that satisfies IEC standard pub.61558.

The multilayer insulated wire of the present invention is a multilayer insulated wire in which the insulating layer to be coated is composed of at least 3 layers, preferably 3 layers. Preferred embodiments thereof and resins for forming the respective layers will be described.

The outermost layer (a) of the multilayer insulated wire of the present invention is an extruded coating layer made of a polyamide resin. As a polyamide resin suitable for use as the outermost insulating layer, nylon 6, 6[ "a-125": trade name, "Amilan CM-3001" manufactured by Unitika corporation: trade name, manufactured by Tolli corporation ], nylon 4, 6[ "F-5000": trade name, "C2000", manufactured by Unitika: trade name, manufactured by imperial corporation ], nylon 6, T [ "ArlenAE-420": trade name, manufactured by mitsui petrochemical co ], polyphthalamide [ "amodel pxm 04049": trade name, Solvay Co., Ltd. ], and the like.

The extruded coating layer of the outermost layer (a) made of a polyamide resin can have a thickness of 25 μm or less, preferably 10 to 20 μm, because the extruded coating layer has good withstand voltage characteristics even when the extruded coating layer is thin. If the film thickness is too thin, the heat resistance is lowered, and if it is too thick, the withstand voltage characteristics are lowered.

The inner layer (B) of the multilayer insulated wire of the present invention is composed of an extruded coating layer containing a crystalline resin having a melting point of 225 ℃ or higher, preferably 250 ℃ or higher. If the melting point is too low, the heat resistance is insufficient, and the heat resistance type B is not satisfied, and thus the coating layer is not suitable.

Examples of the crystalline resin having a melting point of 225 ℃ or higher include a polyethylene terephthalate resin, a polybutylene terephthalate resin, and a polybutylene naphthalate resin, and a polyethylene terephthalate resin which is a thermoplastic linear polyester resin described later is particularly preferable.

The inner layer (B) of the insulated multilayer wire of the present invention may be an extruded coating layer containing an amorphous resin having a glass transition temperature of 200 ℃ or higher, preferably 220 ℃ or higher. Even in the case of an amorphous resin, if the glass transition temperature is too low, the heat resistance is insufficient, and as a result, the heat resistance does not satisfy the B-type heat resistance, and therefore, the resin is not suitable as a coating layer.

Examples of such an amorphous resin include polysulfone resins, polyethersulfone resins, and polyetherimide resins, and preferably polyethersulfone resins, which are amorphous resins described later.

In a preferred embodiment of the present invention, the inner layer (B) of the insulating layer made of a crystalline resin having a melting point of 225 ℃ or higher is an extruded coating layer containing a thermoplastic linear polyester resin in which an aliphatic alcohol component and an acid component are bonded to each other in whole or in part.

As the thermoplastic linear polyester resin, a resin obtained by an esterification reaction between an aromatic dicarboxylic acid or a dicarboxylic acid a part of which is substituted with an aliphatic dicarboxylic acid, and an aliphatic diol is preferably used. For example, polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polyethylene naphthalate resin (PEN), and the like are given as typical examples.

Examples of the aromatic dicarboxylic acid used for synthesizing the thermoplastic linear polyester resin include terephthalic acid, isophthalic acid, phthalic acid (テレフタルヅカルボン acid), diphenylsulfone dicarboxylic acid, diphenoxyethanedicarboxylic acid, diphenyl ether carboxylic acid, methyl terephthalic acid, and methyl isophthalic acid. Among these, terephthalic acid is particularly preferable.

Examples of the aliphatic dicarboxylic acid substituted for the partially aromatic dicarboxylic acid include succinic acid, adipic acid, and sebacic acid. The substitution amount of these aliphatic dicarboxylic acids is preferably less than 30 mol%, particularly preferably less than 20 mol%, based on the aromatic dicarboxylic acid.

On the other hand, examples of the aliphatic diol used in the esterification reaction include ethylene glycol, 1, 3-propanediol, tetramethylene glycol, hexanediol, and decanediol. Of these, ethylene glycol and tetramethylene glycol are suitable. Further, as the aliphatic diol, an oxadiol such as polyethylene glycol or polytetramethylene glycol may be used as a part thereof.

As the commercially available thermoplastic linear polyester resin which can be preferably used in the present invention, polyethylene terephthalate (PET) resins include "Vylopet" (trade name: manufactured by Toyobo Co., Ltd), "Bellpet" (trade name: manufactured by Bell Ltd), "Diyan PET" (trade name: manufactured by Diyan Co., Ltd.). Examples of the polyethylene naphthalate (PEN) resin include "Diyan PEN" (trade name: manufactured by Diyan corporation); examples of the polycyclohexanedimethanol terephthalate (PCT) resin include "Ektar" (trade name: manufactured by Toray corporation).

The resin constituting the inner layer (B) is preferably a resin mixture obtained by blending 5 to 40 parts by mass of an ethylene copolymer having a carboxylic acid or a metal salt of a carboxylic acid in a side chain thereof with 100 parts by mass of a thermoplastic linear polyester resin as a crystalline resin having a melting point of 225 ℃ or higher.

The resin mixture preferably contains, for example, a vinyl copolymer in which a carboxylic acid or a metal salt of a carboxylic acid is bonded to a side chain of polyethylene. The ethylene copolymer has an effect of inhibiting crystallization of the thermoplastic linear polyester resin.

Examples of the carboxylic acid bonded to the ethylene copolymer include unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; or unsaturated dicarboxylic acids such as maleic acid, fumaric acid, and phthalic acid, and examples of the metal salts thereof include salts of Zn, Na, K, and Mg.

Examples of such an ethylene copolymer include a resin generally called ionomer (for example, "himiran"; trade name, manufactured by mitsui polymers), an ethylene-acrylic acid copolymer (for example, "EAA"; trade name, manufactured by dow chemical), and an ethylene graft polymer having a carboxylic acid in a side chain (for example, "Admer"; trade name, manufactured by mitsui petrochemical co).

In the resin mixture constituting the inner layer (B) of this embodiment, the blending ratio of the thermoplastic linear polyester resin and the ethylene copolymer having a carboxylic acid or a metal salt of a carboxylic acid in a side chain thereof is preferably in the range of 5 to 40 parts by mass relative to 100 parts by mass of the former. If the latter blend amount is too small, the heat resistance of the insulating layer formed is not problematic, but the crystallization-inhibiting effect of the thermoplastic linear polyester resin is small, and therefore, a so-called crack phenomenon, which is a fine crack, may occur on the surface of the insulating layer during coil processing such as bending. In addition, the insulation breakdown voltage may be significantly reduced as the deterioration of the insulation layer progresses over time. On the other hand, if the amount is too large, the heat resistance of the insulating layer is significantly deteriorated. The more preferable blending ratio of the two is 7 to 25 parts by mass relative to 100 parts by mass of the former.

In another preferred embodiment, the inner layer (B) is an extruded coating layer of a resin mixture in which 1 to 20 parts by mass of a resin having an epoxy group is blended with 100 parts by mass of a thermoplastic linear polyester resin (a crystalline resin having a melting point of 225 ℃ or higher formed by bonding an aliphatic alcohol component and an acid component). The thermoplastic linear polyester resin is the same as the thermoplastic linear polyester resin in the above embodiment and the preferable range is also the same. The epoxy group is a functional group reactive with the thermoplastic linear polyester resin. The epoxy group-containing resin preferably contains 1 to 20 parts by mass of a monomer component containing the functional group, and more preferably 2 to 15 parts by mass. The resin is preferably a copolymer containing an epoxy group-containing compound component. Examples of the reactive epoxy group-containing compound include glycidyl ester compounds of unsaturated carboxylic acids represented by the following general formula (1).

General formula (1)

[ 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, and glycidyl itaconate, and among them, glycidyl methacrylate is preferable.

Representative examples of the epoxy group-containing resin reactive with the thermoplastic linear polyester resin include ethylene/glycidyl methacrylate copolymers, ethylene/glycidyl methacrylate/methyl acrylate terpolymers, ethylene/glycidyl methacrylate/vinyl acetate terpolymers, and ethylene/glycidyl methacrylate/methyl acrylate/vinyl acetate tetrapolymers. Among them, ethylene/glycidyl methacrylate copolymer and ethylene/glycidyl methacrylate/methyl acrylate terpolymer are preferable. Examples of commercially available resins include "Bondfast" (trade name: manufactured by Sumitomo chemical Co., Ltd.) and "Lotader" (trade name: manufactured by ATOFINA).

In the resin mixture constituting the inner layer (B) of this embodiment, the blending ratio of the thermoplastic linear polyester resin to the epoxy group-containing resin is preferably set in the range of 1 to 20 parts by mass with respect to 100 parts by mass of the former. If the latter blend amount is too small, the crystallization-inhibiting effect of the thermoplastic linear polyester resin becomes small, and therefore, a so-called crack phenomenon, which is a fine crack, may occur on the surface of the insulating layer during coil processing such as bending. In addition, the deterioration of the insulating layer with time progresses, and the insulation breakdown voltage may be significantly reduced. On the other hand, if the amount is too large, the heat resistance of the insulating layer is significantly reduced, and the heat-resistant B species is not satisfied. The more preferable blending ratio of the two is 2 to 15 parts by mass relative to 100 parts by mass of the former.

In the present invention, the carboxyl group and the epoxy group in the thermoplastic linear polyester resin are reacted with each other, whereby the deterioration with time and the embrittlement of the resin are suppressed, and a multilayer insulated wire having excellent flexibility is obtained.

The base resin component constituting the inner layer (B) in another embodiment is a polyester resin composition containing a polyester resin containing 75 to 95 mass% of a crystalline resin having a melting point of 225 ℃ or higher other than the liquid crystal polymer and 5 to 25 mass% of a liquid crystal polymer having a melting point of 225 ℃ or higher. Any method can be used for mixing the liquid crystal polymer with the polyester resin other than the liquid crystal polymer.

Hereinafter, the liquid crystal polymer used in the present invention will be described.

The liquid crystal polymer to be used is not particularly limited in its molecular structure, density, molecular weight, and the like, and is preferably a melt liquid crystal polymer (thermotropic liquid crystal polymer) which forms liquid crystals when melted. Among the melt-crystalline polymers, melt-crystalline polyester copolymers are preferred.

Examples of such a melt-crystalline polyester include: (I) a copolyester in which rigid components obtained by block copolymerization of 2 kinds of rigid linear polyesters having different lengths are copolymerized with each other; (II) a nonlinear structure-introduced polyester obtained by block copolymerization of a rigid linear polyester and a rigid nonlinear polyester; (III) a curved chain-introducing polyester obtained by copolymerizing a rigid-linear polyester and a flexible polyester; (IV) an aromatic nucleus-substituted aromatic introduction type polyester obtained by introducing a substituent to an aromatic ring of a linear polyester by a rigid chain.

Examples of the repeating unit of such a polyester include, but are not limited to, a unit derived from an aromatic dicarboxylic acid, b unit derived from an aromatic diol, and c unit derived from an aromatic hydroxycarboxylic acid.

a. Repeating units derived from aromatic dicarboxylic acids:

b. repeating units derived from an aromatic diol:

c. repeating units derived from aromatic hydroxycarboxylic acids:

from the viewpoint of the balance of workability, heat resistance, mechanical properties of the insulating film, and the like in the film forming step of the coating layer, the liquid crystal polymer preferably contains the following repeating unit, and more preferably the content of the repeating unit is at least 30 mol% or more of the total repeating units.

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

The production method of such a polyester resin as a liquid crystal polymer is described in, for example, Japanese patent laid-open publication No. 2-51523, Japanese patent publication No. 63-3888, and Japanese patent publication No. 63-3891.

Among these, the combinations shown in (I), (II) and (V) are preferable, and the combination shown in (V) is more preferable.

The polyester resin of the liquid crystal polymer has a slightly higher melting point and a flow temperature of 300 ℃ or higher than those of the polyamide resin and the thermoplastic polyester used in the present invention. Further, since the viscosity of the polyester resin of the liquid crystal polymer at the time of melting is also equal to or lower than that of polyethylene terephthalate and 6, 6 nylon, the polyester resin can be extruded at high speed and subjected to a coating treatment, and the insulating coating layer can be formed at low cost.

The liquid crystal polymer film, on the contrary, is characterized by extremely low elongation (of several percent) and has a problem in flexibility. Therefore, by blending a polyester resin other than the liquid crystal polymer, such as polybutylene terephthalate, polyethylene terephthalate, or polyethylene naphthalate, with the liquid crystal polymer, the stretchability of the coating film can be improved, and the flexibility can be improved.

The resin forming the inner layer (B) of the present invention preferably contains a resin mixture containing a resin having an epoxy group in a base resin component containing the liquid crystal polymer and a polyester resin as a polymer other than a liquid crystal, the resin mixture having the polyester resin as a continuous layer and the resin having the epoxy group as a dispersed phase. The content of the resin having an epoxy group is preferably 1 to 20 parts by mass, more preferably 2 to 15 parts by mass, based on 100 parts by mass of the base resin component of the polyester resin.

If the amount of the resin having an epoxy group is more than 20 parts by mass, the heat resistance is slightly lowered. This is presumably because the heat resistance of the epoxy group-containing resin component is lower than that of Liquid Crystal Polymer (LCP) or PET.

Representative examples of the resin having an epoxy group include an ethylene/glycidyl methacrylate copolymer, an ethylene/glycidyl methacrylate/methyl acrylate terpolymer, an ethylene/glycidyl methacrylate/vinyl acetate terpolymer, and an ethylene/glycidyl methacrylate/methyl acrylate/vinyl acetate tetrapolymer. Among them, ethylene/glycidyl methacrylate copolymer and ethylene/glycidyl methacrylate/methyl acrylate terpolymer are preferable. Examples of commercially available resins include "Bondfast" (trade name: manufactured by Sumitomo chemical Co., Ltd.) and "Lotader" (trade name: manufactured by ATOFINA).

In another embodiment, the resin constituting the inner layer (B) preferably contains a polyphenylene sulfide resin as a crystalline resin having a melting point of 225 ℃. In the present invention, the polyphenylene sulfide resin having a low crosslinking degree is preferable in terms of obtaining good extrudability as a coating layer of the multilayer insulated wire. However, the crosslinked polyphenylene sulfide resin may be combined or the crosslinking component, the branch component, or the like may be contained in the polymer as long as the resin characteristics are not impaired.

The polyphenylene sulfide resin having a low degree of crosslinking is preferably a resin having an initial tan δ (loss modulus/storage modulus) value of 1.5 or more, most preferably 2 or more, under nitrogen at 1rad/s and 300 ℃. The upper limit is not particularly limited, and the value of tan δ may be 400 or less, or may be more than 400. The tan δ used in the present invention can be easily evaluated by measuring the time dependence of the loss modulus and storage modulus at the above-mentioned fixed frequency and fixed temperature in nitrogen gas, and particularly, the tan δ used in the present invention can be calculated from the initial loss modulus and storage modulus immediately after the start of the measurement. For the measurement, a sample having a diameter of 24mm and a thickness of 1mm was used. An example of an apparatus capable of performing these measurements is an ARES (Advanced rheometric expansion System, trade name) apparatus manufactured by TA Instruments Japan. The tan δ mentioned above is a criterion of the crosslinking level, and it is difficult to obtain sufficient flexibility and to obtain a good appearance with the polyphenylene sulfide resin having tan δ of less than 2.

As a resin constituting the inner layer (B) of still another embodiment, a resin containing a polyether sulfone resin as an amorphous resin having a glass transition temperature of 200 ℃ or higher can be cited. It is preferable to use a substance represented by the following general formula (2).

General formula (2)

[ in the formula, R¹Represents a single bond or-R²-O-(R²Is phenylene, biphenylene, or

(R³represents-C (CH)₃)₂-、-CH₂-isoalkylene), R²The group (c) may have a substituent. ). n represents a positive integer.]

The method for producing the resin is known per se, and as an example, a method for producing the resin by reacting dichlorodiphenyl sulfone, bisphenol S and potassium carbonate in a high boiling point solvent is given. Commercially available resins include SumikaexcelPES (trade name: manufactured by Sumitomo chemical Co., Ltd), "Radel A" and "Radel R" (trade name: manufactured by Amoco Ltd.).

Preferred multilayer insulated wires according to the present invention will be described with reference to the accompanying drawings. As shown in fig. 3, a multilayer insulated wire 11 having a 3-layer structure of an outermost layer 12, an inner layer (B1)13 in contact with the outermost layer, and an inner layer (B2)14 inside the inner layer can be obtained. Fig. 3 shows a multilayer insulated wire having 3 layers, but the number of insulating layers may be 3 or more.

In the multilayer insulated wire of the present invention, the resins forming the respective layers are preferably the same among the 2 or more inner layers (B) located inside the outermost layer (a), but they may be different. In different cases, the layers may be combined using different resin mixtures as described in the above embodiments, or may be combined using a resin mixture and a resin composition.

The inner layer (B1) in contact with the outermost layer (a) is preferably a polyphenylene sulfide resin as a crystalline resin having a melting point of 250 ℃ or higher. The polyphenylene sulfide resin is preferably one having excellent extrusion processability and a low degree of crosslinking. The resin forming the inner layer (B2) on the inner side of the inner layer (B1) is preferably a resin mixture obtained by blending 1 to 20 parts by mass of a resin having an epoxy group with 100 parts by mass of a thermoplastic linear polyester resin having a melting point of 225 ℃ or higher as a crystalline resin. As the thermoplastic linear polyester resin, the same resin as that in the above embodiment can be used.

Other heat-resistant resins, commonly used additives, inorganic fillers, processing aids, colorants, and the like can be added to the resin forming each insulating layer in the present invention within a range that does not impair the required characteristics.

As the conductor used in the multilayer insulated wire of the present invention, a bare metal wire (element wire), an insulated wire in which a enamel layer or a thin-walled insulating layer is provided on a bare metal wire, or a multi-core stranded wire in which a plurality of bare metal wires or a plurality of enamel-covered insulated wires or thin-walled insulated wires are twisted can be used. The number of strands of these strands can be selected at will according to the high frequency application. In the case where the number of core wires (conductor bundles (adjacent lines)) is large (for example, 19-conductor bundles or 37-conductor bundles), the core wires may not be stranded wires. In the case where the twisted wire is not used, for example, only 2 or more wire bundles may be bundled in parallel, or the bundled wire bundles may be twisted at a very large pitch. It is preferred in either case to make the cross-section substantially circular.

The multilayer insulated wire of the present invention can be produced by extruding and coating the 1 st insulating layer of a desired thickness on the outer periphery of the conductor, then extruding and coating the 2 nd insulating layer of a desired thickness on the outer periphery of the 1 st insulating layer, and further extruding and coating the outermost insulating layer, and then sequentially extruding the coated insulating layers by a conventional method. In the case of 3 layers, the thickness of the entire extruded insulation layer thus formed is preferably in the range of 50 to 180 μm. This is because, if the thickness of the entire insulating layer is too thin, the electrical characteristics of the obtained heat-resistant multilayer insulated wire are greatly reduced, and it may be unsuitable for practical use; conversely, if the thickness is too large, the size may not be reduced, and the coil may be difficult to process. A more preferable range is 60 to 150 μm. When the polyamide resin is used as the outermost layer, the thickness of the outermost layer is preferably 25 μm or less, and more preferably 10 to 20 μm.

As an embodiment of the transformer using the multilayer insulated wire, a configuration of: as shown in fig. 1, in the bobbin 2 on the ferrite core 1, the 1-time winding wire 4 and the 2-time winding wire 6 are formed without assembling an insulation barrier or an insulation tape layer. In addition, the multilayer insulated wire of the present invention described above is also applicable to other types of transformers.

Examples

The present invention will be described in further detail below based on examples, but the present invention is not limited thereto.

Examples 1 to 11 and comparative examples 1 to 6

As a conductor, a soft copper wire having a wire diameter of 1.0mm was prepared. The composition (numerical values of the composition indicate parts by mass) and thickness of each layer of the extrusion coating resin shown in table 1 were sequentially extruded and coated on a conductor to produce a multilayer insulated wire. In Table 1, "-" indicates no blending.

The abbreviations in table 1 represent the respective resins as follows. The melting point or glass transition temperature of each resin was measured using a Differential Scanning calorimeter (Differential Scanning calorimeter) (trade name: DSC-60, manufactured by Shimadzu corporation).

Polyamide resin: "FDK-1" (trade name: manufactured by Unitika Co., Ltd.), Polyamide 66 resin (melting point: 260 ℃ C.)

PPS resin: "FZ-2200-A8" (trade name: DIC Co., Ltd.), polyphenylene sulfide resin (melting point: 280 ℃ C.)

PET resin: "Diren PET" (trade name: manufactured by Diren Co., Ltd.), polyethylene terephthalate resin (melting point: 260 ℃ C.)

LCP resin: "Rodrun LC 5000" (trade name: manufactured by Unitika Co., Ltd.), liquid-crystalline polyester resin (melting point: 280 ℃ C.)

Epoxy-containing resin: "Bondfast 7M" (trade name: manufactured by Sumitomo chemical industries, Ltd.) (melting point: 52 ℃ C.)

Ethylene copolymer: "Himilan 1855" (trade name: manufactured by Sanjing DuPont) (melting Point: 86 ℃ C.)

PES resin: "Sumikaexcel PES 4100" (trade name: manufactured by Sumitomo chemical Co., Ltd.), polyether sulfone resin (glass transition temperature: 225 ℃ C.)

The obtained multilayer insulated wire was tested for various properties in the following manner. In addition, the appearance was observed with the naked eye. The results obtained are shown in Table 1.

A. Flexibility test:

the wire itself was tightly wound around 10 turns so as to be in contact with the wire, and observed with a microscope, and if no abnormality such as a crack or a fissure was observed in the coating film, the coating film was regarded as acceptable and indicated by "o".

B. Electrical heat resistance:

evaluation was carried out by the following test method following IEC standard 61558.

While applying a load of 9.4kg, the multilayer insulated wire was wound around a mandrel having a diameter of 1.0mm for 10 turns, heated at 225 ℃ for 1 hour, further heated at 150 ℃ for 21 hours and heated at 200 ℃ for 3 hours in a cyclic manner, further kept in an atmosphere having a humidity of 95% at 30 ℃ for 48 hours, and thereafter applied with a voltage of 5500V for 1 minute, and if there is no short circuit, it was judged that the type B was acceptable, and indicated by "O". (in the determination, n is 5 evaluation, even if 1 short circuit, also for disqualification, indicated by "x").

C. Solvent resistance:

the electric wire wound in 20D (20 times the diameter of the conductor) as a winding wire was immersed in a solvent of xylene and isopropyl alcohol for 30 seconds, dried, and then visually observed on the surface of the sample to determine whether or not a crack was generated. In table 1, the sample with no crack was indicated as "o", and the sample with crack was indicated as "x". No crack formation was observed in all samples.

D. Whether qualified or not:

further, these test results of A, B, C were collected to determine whether or not the insulated electric wire was acceptable, and the preferable results were indicated by "o" and the inappropriate results were indicated by "x".

The following is clear from the results shown in table 1.

In comparative examples 1 to 4, the film thickness of the polyamide resin as the outermost layer was increased to 30 μm, and the electrical heat resistance was not satisfactory. In comparative examples 5 and 6, when the polyester resin was used as the outermost layer, the electrical heat resistance was not satisfactory regardless of the film thickness. On the other hand, in examples 1 to 11, any one of flexibility, electrical heat resistance, chemical resistance and wire appearance satisfied the standards of acceptability.

Industrial applicability

The invention provides a multilayer insulated wire which not only satisfies the requirements of heat resistance and voltage resistance, but also has good processability after soldering which is required for coil application.

The present invention has been described above together with embodiments thereof, but it is not intended that the present invention be limited to any details for the purpose of illustration, unless otherwise specified in the application, and should be construed as broadly as possible without departing from the spirit and scope of the invention as set forth in the appended claims.

The present application claims priority based on japanese patent application 2009-.

Description of the symbols

1 ferrite core

2 Transformer framework

3 insulating barrier

4 primary winding wire

4a conductor

4b, 4c, 4d insulating layer

5 insulating adhesive tape

6 Secondary winding wire

6a conductor

6b, 6c, 6d insulating layer

Claims (10)

1. A multilayer insulated wire comprising a conductor and at least 3 extruded insulating layers covering the conductor, wherein the outermost layer (A) of the insulating layers is composed of an extruded coating layer of a polyamide resin and has a film thickness of 25 μm or less; the inner layer (B) of the insulating layer is composed of an extruded coating layer containing a crystalline resin having a melting point of 225 ℃ or higher or an amorphous resin having a glass transition temperature of 200 ℃ or higher, wherein the inner layer (B) is an inner layer.

2. The multilayer insulated wire according to claim 1, wherein the resin forming the inner layer (B) of the insulating layer contains a crystalline resin having a melting point of 225 ℃ or higher, and the crystalline resin is a thermoplastic linear polyester resin.

3. The multilayer insulated wire according to claim 1 or 2, wherein the resin forming the inner layer (B) of the insulating layer comprises a resin mixture obtained by blending 5 to 40 parts by mass of an ethylene copolymer having a carboxylic acid or a metal salt of a carboxylic acid in a side chain with 100 parts by mass of a crystalline resin having a melting point of 225 ℃ or higher, the crystalline resin being a thermoplastic linear polyester resin.

4. The multilayer insulated wire according to claim 1 or 2, wherein the resin forming the inner layer (B) of the insulating layer contains a resin mixture obtained by blending 1 to 20 parts by mass of a resin having an epoxy group with 100 parts by mass of a crystalline resin having a melting point of 225 ℃ or higher, the crystalline resin being a thermoplastic linear polyester resin.

5. The multilayer insulated wire according to claim 1, wherein the base resin component forming the inner layer (B) of the insulating layer is composed of 75 to 95 mass% of a crystalline resin having a melting point of 225 ℃ or higher and 5 to 25 mass% of a liquid crystal polymer having a melting point of 225 ℃ or higher, the crystalline resin being a polyester resin, and the liquid crystal polymer being a polyester resin, excluding the liquid crystal polymer.

6. A multilayer insulated wire as set forth in claim 5, characterized in that the resin forming the inner layer (B) of the insulating layer contains 1 to 20 parts by mass of a resin having an epoxy group per 100 parts by mass of the base resin component.

7. The multilayer insulated wire according to claim 1, wherein the resin forming the inner layer (B) of the insulating layer contains a crystalline resin having a melting point of 225 ℃ or higher, and the crystalline resin is a polyphenylene sulfide resin.

8. The multilayer insulated wire according to claim 1, wherein the resin forming the inner layer (B) of the insulating layer contains an amorphous resin having a glass transition temperature of 200 ℃ or higher, and the amorphous resin is a polyether sulfone resin.

9. The multilayer insulated wire according to claim 1, wherein the inner layer (B1) in contact with the outermost layer (A) of the insulating layer is a crystalline resin having a melting point of 225 ℃ or higher, the crystalline resin is a polyphenylene sulfide resin, at least 1 layer of the inner layers (B2) other than the inner layer (B1) contains 1 to 20 parts by mass of a resin having an epoxy group per 100 parts by mass of a crystalline resin having a melting point of 225 ℃ or higher, and the crystalline resin is a thermoplastic linear polyester resin.

10. A transformer formed using the multilayer insulated wire according to any one of claims 1 to 9.