JP2012051966A - Epoxy-modified polyphenylene ether, insulated wire using the same, electric machine coil and motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulated wire that has a high corona discharge starting voltage and satisfies demand characteristics such as heat resistance, mechanical strength, etc., and a resin material used therefor.SOLUTION: The epoxy-modified polyphenylene ether is obtained by reacting a polyphenylene ether with an epoxy compound. The epoxy-modified polyphenylene ether vanish comprises the epoxy-modified polyphenylene ether and a block isocyanate. The electric insulated wire is an electric insulated wire having a conductor and an insulating layer of monolayer or multilayer coating the conductor in which at least one layer of the insulating layer is a resin layer formed by coating it with the epoxy-modified polyphenylene ether varnish or a mixed resin varnish of the epoxy-modified polyphenylene ether and a polyamide-imide or a polyester imide.

Description

  The present invention relates to an insulated wire used for a coil or the like, and more particularly to an insulated wire having an insulating film having a high partial discharge (corona discharge) starting voltage and a resin forming an insulating layer of the insulated wire.

  In an electric device having a high applied voltage, for example, a motor used at a high voltage, a high voltage is applied to an insulated wire constituting the electric device, and partial discharge (corona discharge) is likely to occur on the surface of the insulating film. The generation of corona discharge tends to cause local temperature rise and generation of ozone and ions. As a result, there has been a problem that the insulation coating of the insulated wire is deteriorated to cause dielectric breakdown at an early stage and shorten the life of the electrical equipment.

  In an insulated wire used as a coil winding for a motor or the like, an insulating layer (insulating film) covering a conductor is required to have excellent insulation, adhesion to the conductor, heat resistance, mechanical strength, and the like. Furthermore, the insulated wire used at a high voltage is also required to improve the corona discharge starting voltage for the above reasons.

  If there is a minute gap in the insulating layer or between the coil wires, the electric field concentrates on the portion and corona discharge is likely to occur. In order to prevent corona discharge, Patent Document 1 discloses that a coil is formed by applying a heat-bonding resin to the outside of an insulating layer formed on a conductor and then winding the baked insulated wire, and then heating and heat-bonding. A coil forming method is disclosed in which a resin is dissolved to fill an air layer between wires.

  As another method for preventing the occurrence of corona discharge, there is an insulated wire in which a conductive layer or a semiconductive layer having a surface resistance of 1 kΩ to 1 MΩ is formed outside the insulating layer formed on the conductor (patent) Literature 2 etc.). By the conductive layer or semiconductive layer outside the insulating layer, the electrostatic potential gradient generated on the surface of the insulating layer becomes gentle and the corona discharge start voltage can be improved.

  Further, the corona discharge starting voltage can be improved by reducing the dielectric constant of the insulating layer. Polyimide resin and fluororesin have a low dielectric constant, and the corona discharge starting voltage is improved by using these materials as an insulating layer. Patent Document 3 discloses an insulated wire using a mixed resin of polyesterimide and polyethersulfone as an insulating layer.

JP-A-10-261321 JP 2004-254457 A JP 2009-277369 A

  In the method using the heat-sealing resin as in Patent Document 1, a heat-sealing process is required after the coil is formed, and the manufacturing cost is increased. In the method using a conductive layer or a semiconductive layer, although the corona discharge starting voltage is improved, the surface current of the insulated wire is reduced by the conductive layer and the semiconductive layer, so that the leakage current flowing on the surface of the wire during AC energization is reduced. The surface of the insulated wire is heated and easily deteriorates. Moreover, since there exists a possibility that the conductor exposed part of an insulated wire terminal, a conductive layer, and a semiconductive layer may short-circuit, the process of peeling a conductive layer and a semiconductive layer is needed at the insulated wire terminal.

  Although the method using a low dielectric constant of the insulating layer is effective for improving the corona discharge starting voltage, the insulating layer has not only a low dielectric constant but also insulation, adhesion to conductors, heat resistance, mechanical strength, etc. The required characteristics vary depending on the intended use. Material cost is also an important factor in material selection. Polyimide resin has a low dielectric constant and is excellent in heat resistance, mechanical strength, etc., but the cost is high, and when polyimide is used as an insulating layer, an insulated wire becomes expensive. In addition, although the fluororesin has a low dielectric constant, it is soft and inferior in heat resistance and mechanical strength, so its use is limited when used as an insulating layer. The insulating material described in Patent Document 3 has a balance of dielectric constant, heat resistance, and mechanical characteristics, but the characteristics may be insufficient depending on the application.

  The inventors pay attention to polyphenylene ether, which is a low dielectric constant material, and by using a varnish that combines polyphenylene ether with low dielectric constant and polyamideimide or polyesterimide, the balance of mechanical properties, heat resistance and dielectric constant is achieved. And found that it can be used as an insulating layer of an insulated wire. Polyphenylene ether is a brittle material with low flexibility (mechanical properties), but it can be used as an insulating layer for insulated wires by combining with polyamideimide or polyesterimide, which is excellent in flexibility.

  The molecular weight and flexibility of polyphenylene ether are correlated, and the higher the molecular weight, the greater the tensile strength and elongation, and the better the flexibility. Therefore, in order to obtain sufficient flexibility, it is necessary to use a higher molecular weight polyphenylene ether. However, polyphenylene ether is a material that is difficult to dissolve in a solvent, and its solubility decreases as the molecular weight increases. Polyphenylene ether having a low molecular weight is excellent in solubility, but polyphenylene ether having a low molecular weight cannot provide sufficient flexibility even when mixed with polyamideimide or polyesterimide.

  This invention is made | formed in view of said problem, and makes it a subject to provide the resin material which can be compatible with the solubility to a solvent and flexibility with low dielectric constant.

  The present invention also provides an insulated wire having a resin layer formed using the above resin material, capable of increasing the corona discharge start voltage, and satisfying required characteristics such as heat resistance and mechanical strength. Is an issue.

  The present invention is an epoxy-modified polyphenylene ether obtained by reacting a polyphenylene ether and an epoxy compound (claim 1).

  An epoxy compound is a compound having an epoxy group. In the present invention, it is preferable to use an epoxy compound having an epoxy group at both ends of the molecule. Among these, the use of an epoxy compound represented by the following formula (1) or formula (2) is preferable in terms of cost (claim 2).

  The polyphenylene ether is represented by the following general formula (3), and preferably has hydroxyl groups at both ends of the molecule.

（式中、Ｒ_１〜Ｒ_６はそれぞれ独立に水素原子又は置換基を有することもある全炭素数１〜２０の炭化水素基を表す。）

(In the formula, R _{1 to} R ₆ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent.)

  By reacting the epoxy group of the epoxy compound with the terminal hydroxyl group of the polyphenylene ether, the polyphenylene ether has a high molecular weight. Therefore, the tensile strength and elongation are improved and the material is excellent in flexibility. Moreover, since the molecular structure of the epoxy compound is introduced into the polyphenylene ether, the solubility in a solvent is improved, and both flexibility and solubility in a solvent can be achieved.

  The weight average molecular weight of the polyphenylene ether is preferably 100 or more and 5,000 or less (Claim 3). If the molecular weight of the polyphenylene ether exceeds 5,000, it will be difficult to dissolve in a solvent and it will be difficult to react well. Further, when the molecular weight is increased, the amount of the epoxy compound introduced into the molecular chain of the epoxy-modified polyphenylene ether after the reaction is relatively reduced, and the effect of improving the solubility in a solvent is reduced.

  The weight average molecular weight of the epoxy-modified polyphenylene ether is preferably 5,000 or more and 100,000 or less (Claim 4). When the molecular weight is less than 5,000, flexibility is lowered. Moreover, when it exceeds 100,000, the solubility to a solvent will become inadequate.

  The epoxy-modified polyphenylene ether can be used alone, but is preferably used as an epoxy-modified polyphenylene ether varnish combined with a curing agent. As the curing agent, blocked isocyanate, melamine-based curing agent, titanium alkoxide and the like can be used. Among these, it is preferable to use a blocked isocyanate (Claim 5). In the epoxy-modified polyphenylene ether, there are a hydroxyl group formed by reacting a hydroxyl group derived from polyphenylene ether and an epoxy group derived from an epoxy compound, an unreacted epoxy group, and a hydroxyl group. When the isocyanate group of the blocked isocyanate reacts with these functional groups, the epoxy-modified polyphenylene ethers are cross-linked to further improve flexibility. Therefore, it can be used alone as a covering material for an insulated wire without being combined with a material having excellent flexibility such as polyamideimide or polyesterimide. A plurality of curing agents may be used in combination.

  The invention according to claim 6 is an insulated wire having a conductor and a single-layer or multi-layer insulation layer covering the conductor, and at least one layer of the insulation layer is coated with the epoxy-modified polyphenylene ether varnish and baked. It is an insulated wire which is a resin layer formed in this way. The resin layer formed by applying and baking the epoxy-modified polyphenylene ether varnish has a low dielectric constant, and can increase the corona discharge starting voltage.

  The invention according to claim 7 is an insulated wire having a conductor and a single-layer or multi-layer insulation layer covering the conductor, wherein at least one of the insulation layers comprises polyamideimide or polyesterimide (A) and the above It is an insulated wire which is the resin layer formed by apply | coating and baking the mixed resin varnish which mixed the epoxy-modified polyphenylene ether of this with the ratio (mass ratio) of A: B = 10: 90-90: 10. A combination of low-permittivity epoxy-modified polyphenylene ether and polyamide-imide or polyester-imide that excels in heat resistance and mechanical properties (flexibility) balances the characteristics of dielectric constant, heat resistance, and flexibility. An insulated wire can be obtained. If the mixed resin varnish further contains a blocked isocyanate as a curing agent, the degree of crosslinking of the epoxy-modified polyphenylene ether is preferably improved (Claim 8).

  The invention according to claim 9 is an electric coil formed by winding the insulated wire. A tenth aspect of the present invention is a motor having the electric coil. These electric coils and motors have a high corona discharge start voltage, and even when a high voltage is applied, the insulating film is hardly deteriorated, so that the life can be extended.

  According to the present invention, it is possible to obtain an epoxy-modified polyphenylene ether having a low dielectric constant and capable of satisfying both solubility in a solvent and flexibility. In addition, the insulated wire of the present invention has a resin layer formed using the above-mentioned epoxy-modified polyphenylene ether, thereby improving the corona discharge starting voltage and satisfying required characteristics such as heat resistance and mechanical strength. .

It is a schematic diagram explaining the measuring method of a dielectric constant. It is a schematic diagram explaining the test sample for a corona discharge start voltage measurement. It is a cross-sectional schematic diagram which shows an example of this invention. It is a schematic diagram which shows an example of the coil of this invention. It is a schematic diagram which shows an example of the motor structural member of this invention.

  As polyphenylene ether, what is shown by following formula (4) can be used preferably. Specifically, PPO (registered trademark) resin or the like made from SABIC Innovative Plastics can be used. It is preferable to select a polyphenylene ether having a molecular weight of about 100 to 5,000.

  As an epoxy compound, what is shown by following formula (1) or formula (2) can be used preferably. In addition, any epoxy compound having an epoxy group at both ends can be used. From the viewpoints of versatility and cost, bisphenol S type and bisphenol F type epoxy compounds are preferred. An epoxy compound may be used independently and may combine 2 or more types.

  When polyphenylene ether and an epoxy compound are mixed and reacted by heating in an organic solvent, an epoxy-modified polyphenylene ether is obtained. When the total amount (equivalent) of the polyphenylene ether and the total amount (equivalent) of the epoxy compound is about 1: 1, the reaction proceeds favorably.

  As the organic solvent, cyclohexanone, naphtha, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, tetramethylurea, hexaethyl phosphate triamide, γ-butyrolactam, etc. are used. it can. These organic solvents may be used alone or in combination of two or more.

  The amount of the organic solvent is not particularly limited as long as it can uniformly disperse the polyphenylene ether and the epoxy compound, but usually 40 parts by mass to 100 parts by mass is used per 100 parts by mass of the total amount of these components. If the amount of the organic solvent is reduced, the amount of the solid content of the epoxy-modified polyphenylene ether varnish obtained is increased, which is effective for cost reduction.

  The reaction between the polyphenylene ether and the epoxy compound is carried out, for example, by mixing the materials, adding an organic solvent, and reacting at a temperature of about 60 ° C. to 140 ° C. for several hours. The reaction is preferably performed in an inert gas atmosphere such as nitrogen gas or argon gas. Further, it is preferable to add a reaction catalyst such as imidazole because the reaction easily proceeds. By the reaction, polyphenylene ether and epoxy compound are polymerized to produce epoxy-modified polyphenylene ether. The molecular weight of the produced epoxy-modified polyphenylene ether can be controlled by adjusting the amount of each component charged, the reaction time, and the like. When the molecular weight of the epoxy-modified polyphenylene ether is 5,000 or more and 100,000 or less, it is preferable because the properties are balanced. In addition, the molecular weight here is a weight average molecular weight, and is a value measured by gel permeation chromatography (GPC).

  The obtained epoxy-modified polyphenylene ether solution is diluted to an appropriate concentration before use. It is more preferable to use it mixed with blocked isocyanate. The blocked isocyanate is obtained by blocking the terminal isocyanate group of the polyfunctional isocyanate with a blocking agent. By heating in the baking process of the varnish, the blocking agent is dissociated and an isocyanate group is generated. This isocyanate group crosslinks the epoxy-modified polyphenylene ether.

  Examples of the polyfunctional isocyanate include tolylene diisocyanate, hexamethylene diisocyanate (HDI), diphenylmethane diisocyanate (MDI), and the like. Examples of the blocking agent include alcohols and oximes. The blocked isocyanate is preferably added in an amount of about 5 to 30 parts by mass per 100 parts by mass of the solid content of the epoxy-modified polyphenylene ether.

  The epoxy-modified polyphenylene ether may be used by mixing with polyamideimide or polyesterimide. Even in this case, it is preferable to further use the blocked isocyanate.

  As the polyesterimide, those represented by the following general formula (5) can be preferably used.

式中、Ｒ^１はトリカルボン酸無水物の残基等の３価の有機基、Ｒ^２はジオールの残基等の２価の有機基、Ｒ^３はジアミンの残基等の２価の有機基である。

In the formula, R ¹ is a trivalent organic group such as a residue of tricarboxylic anhydride, R ² is a divalent organic group such as a residue of diol, and R ³ is a divalent organic group such as a residue of diamine. It is.

  The polyesterimide can be obtained by reacting tricarboxylic anhydride, diol, and diamine by a known method. As the tricarboxylic acid anhydride, trimellitic acid anhydride, 3,4,4'-benzophenone tricarboxylic acid anhydride, 3,4,4'-biphenyltricarboxylic acid anhydride, or the like can be used. Of these, trimellitic anhydride is most preferred.

  As the diol, ethylene glycol, propylene glycol, trimethylene glycol, diethylene glycol or the like can be used. As the diamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, m-phenylenediamine, p-phenylenediamine, 1,4-diaminonaphthalene, hexamethylenediamine, diaminodiphenylsulfone and the like can be used.

  As specific products of the polyesterimide, trade names ISOMID 40SM-45 and 40HA-45 manufactured by Hitachi Chemical Co., Ltd., and trade names Neoheat 8625H2 and 8625AY manufactured by Tohoku Paint Co., Ltd. may be used.

  Polyamideimide is obtained by reacting an isocyanate component containing a diisocyanate compound with an acid component. As the isocyanate component, diphenylmethane-4,4′-diisocyanate (MDI), diphenylmethane-3,3′-diisocyanate, diphenylmethane-3,4′-diisocyanate, diphenylether-4,4′-diisocyanate, benzophenone-4,4′- Aromatic diisocyanates such as diisocyanate and diphenylsulfone-4,4′-diisocyanate can be used.

  Acid components include trimellitic anhydride (TMA), 1,2,5-trimellitic acid (1,2,5-ETM), biphenyltetracarboxylic dianhydride, benzophenonetetracarboxylic dianhydride, diphenyl Sulfonetetracarboxylic dianhydride, oxydiphthalic dianhydride (OPDA), pyromellitic dianhydride (PMDA), 4,4 ′-(2,2′-hexafluoroisopropylidene) diphthalic dianhydride, etc. Can be used. The isocyanate component and the acid component may be used one by one or a plurality of types may be combined.

  Polyamideimide or polyesterimide (A) and epoxy-modified polyphenylene ether (B) are mixed so that the solid content ratio is a ratio (mass ratio) of A: B = 10: 90 to 90:10. Increasing the mixing ratio of the epoxy-modified polyphenylene ether (B) can lower the dielectric constant and improve the corona discharge resistance, but the mechanical properties such as heat resistance and flexibility are reduced. The mixing ratio of the imide or polyesterimide (A) and the epoxy-modified polyphenylene ether (B) may be determined. When A: B = 70: 30 to 30:70, the balance of characteristics is good and preferable. Various additives such as pigments, dyes, inorganic or organic fillers, lubricants, reactive low molecules, compatibilizers, and the like may be added to the mixed resin varnish. Furthermore, other resins can be mixed and used within a range not impairing the gist of the present invention.

  An insulating layer is formed by applying and baking an epoxy-modified polyphenylene ether varnish or a mixed resin varnish in which polyamide-imide or polyester-imide (A) and epoxy-modified polyphenylene ether (B) are mixed directly or through another layer. Form. Application and baking can be performed in the same manner as in the production of a normal insulated wire. For example, after the resin varnish is applied to the conductor, an insulating layer is formed by repeating a baking operation by passing the inside of a furnace having a set temperature of 350 to 500 ° C. for 5 to 10 seconds per pass several times. The insulating layer has a thickness of 10 μm to 100 μm.

  As the conductor, copper, copper alloy, aluminum or the like can be used. The size of the conductor and the cross-sectional shape thereof are not particularly limited, but in the case of a round wire, a conductor diameter of 100 μm to 5 mm is generally used, and in the case of a flat wire, one having a side length of 500 μm to 5 mm is generally used.

  The insulating layer may be a single layer or a multilayer. When the insulating layer is a single layer, a resin layer formed by applying and baking the above-described epoxy-modified polyphenylene ether varnish or a mixed resin varnish in which polyamideimide or polyesterimide and epoxy-modified polyphenylene ether are mixed (hereinafter referred to as the first layer). Only the resin layer) becomes the insulating layer. When the insulating layer is a multilayer, another resin layer is formed before or after the first resin layer is formed. It is preferable that the second resin layer further includes a resin mainly composed of polyamideimide because heat resistance is improved. The second resin layer may be in the lower layer or the upper layer of the first resin layer, but polyamideimide having excellent adhesion is used, and the layer made of this highly adhesive polyamideimide resin is adhered to the conductor. The above configuration is preferable because the adhesion of the insulating film to the conductor is improved.

  As the second resin layer, in addition to polyamideimide, polyesterimide, polyimide, polyurethane and the like can be used.

  Furthermore, it is preferable to have a surface lubricating layer as the outermost layer as an insulating layer because workability is improved. The surface lubrication layer is a layer made of a resin having lubricity, and a resin obtained by mixing a lubricant such as various waxes such as carnauba wax, beeswax, montan wax, and microcristan wax, polyethylene, fluororesin, and silicone resin with a binder resin. It can be formed by coating and baking. In this case, insertability and workability are further improved.

  FIG. 3 is a schematic cross-sectional view showing an example of the insulated wire of the present invention. A multi-layer insulating layer is provided outside the conductor 1, and a second resin layer 2, a first resin layer 3 and a surface lubricating layer 4 are formed from the conductor side. The first resin layer is formed by applying and baking an epoxy-modified polyphenylene ether varnish in which epoxy-modified polyphenylene ether and blocked isocyanate are mixed, or a mixed resin varnish in which polyamide-imide or polyesterimide and epoxy-modified polyphenylene ether are mixed. . The insulated wire of the present invention is not limited to this shape, and a single-layer insulated wire having only the first resin layer outside the conductor, or a second resin layer outside the first resin layer. The insulated wire which has may be sufficient.

  FIG. 4A is a schematic diagram showing an example of the electric coil of the present invention, and FIG. 4B is a cross-sectional view taken along the line A-A ′ of FIG. The electric wire 12 is formed by winding the insulated wire 11 outside the core 13 made of a magnetic material. A member composed of a core and an electric coil is used as a rotor or a stator of a motor. For example, as shown in FIG. 5, a stator 15 in which a plurality of divided stators 14 including a core 13 and an electric coil 12 are combined and arranged in an annular shape is used as a constituent member of a motor.

  Next, the present invention will be described in more detail based on examples. The scope of the present invention is not limited to this example.

(Examples 1-6)
(Preparation of epoxy-modified polyphenylene ether)
A polyphenylene ether (PPO made of SABIC Innovative Plastics (registered trademark)) was passed through a flask equipped with a thermometer, a cooling tube, a calcium chloride-filled tube, a stirrer, and a nitrogen blowing tube while flowing 150 ml of nitrogen gas from the nitrogen blowing tube per minute. Trademark) MX90 (molecular weight 1,700) and the epoxy compound and solvent (cyclohexanone) listed in Table 1 were added and heated to 80 ° C. while stirring with a stirrer to dissolve the polyphenylene ether and the epoxy compound. After that, imidazole (manufactured by Shikoku Kasei Co., Ltd., 2E4MZ) was added as a catalyst, and the reaction was performed by increasing the temperature from 80 ° C. to 140 ° C. over 1 hour. Mix the block isocyanate (Nippon Polyurethane Co., Ltd. MS-50) solution and mix at room temperature. The mixture was stirred for a time to obtain an epoxy-modified polyphenylene ether varnish.

(Evaluation of epoxy-modified polyphenylene ether)
The weight average molecular weight of the epoxy-modified polyphenylene ether was measured by gel permeation chromatography. The weight average molecular weight of Example 1 was 37,800, the number average molecular weight was 12,450, the weight average molecular weight of Example 2 was 34,800, and the number average molecular weight was 11,858.

(Polyesterimide varnish adjustment)
The product name Isomoid 40SM-45 manufactured by Hitachi Chemical Co., Ltd. was used as the polyetherimide varnish.

(Preparation of polyamideimide varnish)
TMA (trimellitic anhydride, Mitsubishi Gas Chemical Co., Ltd.) was passed through a flask equipped with a thermometer, a cooling pipe, a calcium chloride filled pipe, a stirrer, and a nitrogen blowing pipe while flowing 150 ml of nitrogen gas from the nitrogen blowing pipe per minute. 108.6 g of MDI (methylene diisocyanate, manufactured by Mitsui Takeda Chemical Co., Ltd., trade name Cosmonate PH) was added. Next, 637 g of N-methylpyrrolidone was added and heated at 80 ° C. for 3 hours while stirring with a stirrer. Further, the temperature of the reaction system was raised to 140 ° C. over about 3 hours and then heated at 140 ° C. for 1 hour. When one hour had passed, heating was stopped and the product was allowed to cool to obtain a polyamideimide resin varnish having a nonvolatile content of 25%.

(Production of insulated wires)
An epoxy-modified polyphenylene ether varnish, or a mixed resin varnish in which an epoxy-modified polyphenylene ether varnish (PPO) and a polyesterimide varnish (PEsI) or a polyamideimide varnish (PAI) were mixed was prepared. A mixed resin varnish was applied and baked on the surface of a conducting wire having a conductor diameter (diameter) of about 1 mm by an ordinary method to form an insulating layer, thereby producing insulated wires of Examples 1 to 6. The mixing ratios in Tables 2 and 3 are the solid content (mass) ratio of epoxy-modified polyphenylene ether, polyamideimide, and polyesterimide.

(Measurement of dielectric constant)
About each obtained insulated wire, the dielectric constant of the insulating layer was measured. As shown in FIG. 1, silver paste was applied to three places on the surface of an insulated wire to prepare a measurement sample (the width of application is 10 mm at both ends and 100 mm at the center). The capacitance between the conductor and the silver paste was measured with an LCR meter, and the dielectric constant was calculated from the measured capacitance value and the film thickness. The measurement results are also shown in Table 1.

(Evaluation of flexibility)
After adding 20% preliminary extension to the obtained insulated wire, a flexibility test was performed based on JIS C3003 7.1. The evaluation was performed by winding the insulated wire around a 1.0 mm round bar for 10 turns and counting the number of turns where film cracking occurred.

(Comparative Example 1)
Polyphenylene ether (PPO (registered trademark) MX90 (molecular weight 1,700) manufactured by SABIC Innovative Plastics) and the epoxy compound, solvent (cyclohexanone) and imidazole (manufactured by Shikoku Kasei Co., Ltd., 2E4MZ) listed in Table 1 were charged. While stirring with a stirrer, each component was dissolved by heating to 80 ° C. After complete dissolution, a dilute solvent and a 27% concentration blocked isocyanate (MS-50, manufactured by Nippon Polyurethane Co., Ltd.) solution were mixed to room temperature. A polyphenylene ether / epoxy compound / block isocyanate mixed varnish was prepared by stirring for 1 hour in the same manner as in Examples 1 to 6. The mixed resin varnish was applied to the surface of a conductor having a conductor diameter (diameter) of about 1 mm in the usual manner. Were coated and baked to produce an insulated wire, and a series of evaluations were performed.

(Comparative Examples 2 and 3)
The above-mentioned polyamideimide varnish (Comparative Example 2) and polyesterimide varnish (Comparative Example 3) are used singly, and a mixed resin varnish is usually applied to the surface of the conductor having a conductor diameter (diameter) of about 1 mm as in Examples 1-6. Insulated wires were prepared by applying and baking by the method, and a series of evaluations were performed. The above results are shown in Tables 1 to 3.

  Examples 1 and 2 are insulated wires using an epoxy-modified polyphenylene ether varnish obtained by mixing an epoxy-modified polyphenylene ether and a curing agent, and have a very low dielectric constant. In addition, it can be seen that even in the flexibility test, the film does not crack and is excellent in flexibility. The insulated wire of Comparative Example 1 in which only polyphenylene ether and an epoxy compound are mixed has a low dielectric constant but a low flexibility.

  Examples 3 to 5 are insulated wires using a varnish obtained by mixing polyamideimide and epoxy-modified polyphenylene ether. The dielectric constant is lower than that of Comparative Example 2 in which polyamideimide is used alone, and the dielectric constant decreases as the mixing ratio of the epoxy-modified polyphenylene ether increases. Example 6 is an insulated wire using a varnish obtained by mixing polyesterimide and epoxy-modified polyphenylene ether. The dielectric constant is lower than that of Comparative Example 3 in which polyesterimide is used alone.

DESCRIPTION OF SYMBOLS 1 Conductor 2 1st resin layer 3 2nd resin layer 4 Surface lubrication layer 11 Insulated wire 12 Electric coil 13 Core 14 Split stator 15 Stator

Claims (10)

  Epoxy-modified polyphenylene ether obtained by reacting polyphenylene ether with an epoxy compound. The epoxy-modified polyphenylene ether according to claim 1, wherein the epoxy compound is a compound represented by the following formula (1) or formula (2).

  The epoxy-modified polyphenylene ether according to claim 2 or 3, wherein the molecular weight of the polyphenylene ether is 100 or more and 5,000 or less.   The epoxy-modified polyphenylene ether according to any one of claims 1 to 3, wherein the molecular weight of the epoxy-modified polyphenylene ether is 5,000 or more and 100,000 or less.   An epoxy-modified polyphenylene ether varnish containing the epoxy-modified polyphenylene ether according to any one of claims 1 to 4 and a blocked isocyanate.   An insulated wire having a conductor and a single-layer or multi-layer insulation layer covering the conductor, wherein at least one of the insulation layers is formed by applying and baking the epoxy-modified polyphenylene ether varnish according to claim 5. An insulated wire that is a resin layer.   It is an insulated wire which has a conductor and the single layer or multilayer insulation layer which coat | covers this conductor, Comprising: At least one layer of the said insulation layer is polyamideimide or polyesterimide (A), and any one of Claims 1-4. A resin layer formed by applying and baking a mixed resin varnish obtained by mixing the epoxy-modified polyphenylene ether (B) described in the above in a ratio (mass ratio) of A: B = 10: 90 to 90:10, Insulated wire.   The insulated wire according to claim 7, wherein the mixed resin varnish further contains a blocked isocyanate.   An electric coil formed by winding the insulated wire according to any one of claims 6 to 8.   A motor having the electric coil according to claim 9.

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