WO2013150991A1 - Insulated electric wire and method for manufacturing same - Google Patents

Abstract

This insulated electric wire is provided with a conductor having aluminum or aluminum alloy as a primary component thereof, and an insulation layer for covering the peripheral surface of the conductor, and is characterized in that the average number of torsions until delamination of the insulation layer in a delamination test is 50 or more. In the present invention, the average value of the dielectric breakdown voltage per unit thickness of the insulation layer in a glycerin solution is preferably at least 0.15 kV/µm. The carbon concentration on the peripheral surface of the conductor is preferably 10 mass% or less. The peripheral surface of the conductor may be processed to reduce carbon. This carbon reduction process may be a washing process using a liquid. The insulation layer may have a primer layer containing a phenoxy resin as a primary component thereof, and a biphenyl-containing polyamide imide layer containing a biphenyl-containing polyamide imide resin as a primary component thereof layered on the peripheral surface of the conductor.

Description

Insulated wire and manufacturing method thereof

The present invention relates to an insulated wire and a method for manufacturing the same.

A coil formed by winding an insulated wire around a constituent element of a general household electric appliance, an automobile, or the like, for example, a motor, an alternator, or an ignition is used. The insulated wire forming such a coil is generally composed of a conductive metal conductor and a resin insulating layer covering the conductive conductor.

As the conductor of the above insulated wire, copper or copper alloy is mainly used because of its high conductivity. On the other hand, aluminum or an aluminum alloy is slightly inferior in conductivity to a copper-based conductor, but is excellent in light weight, and is partially used as a conductor of an insulated wire (see JP 2011-162826 A).

However, insulated wires using aluminum-based conductors generally have lower adhesion between the conductor and the insulating layer than those using copper-based conductors, and therefore have poor wear resistance (scratch resistance) and insulation characteristics. ing. For this reason, in conventional insulated wires using aluminum as a conductor, restrictions on the range of use, processing conditions for coils, and the like are not sufficiently removed.

JP 2011-162826 A

The present invention has been made based on the above-described circumstances, and an object thereof is to provide an insulated wire excellent in adhesion, scratch resistance, and insulation characteristics while using aluminum or an aluminum alloy as a conductor.

The invention made to solve the above problems is
An insulated wire comprising a conductor mainly composed of aluminum or an aluminum alloy and an insulating layer covering the peripheral surface of the conductor,
The average number of twists until the insulating layer is peeled in the peel test is 50 or more.

In the insulated wire, since the average number of twists until the insulating layer is peeled is equal to or more than the lower limit, the aluminum conductor using aluminum or aluminum alloy and the insulating layer are difficult to peel off and have high adhesion. Due to the high adhesion between the aluminum conductor and the insulating layer, the insulated wire is excellent in scratch resistance and insulating properties.

The average value of the dielectric breakdown voltage per unit thickness of the insulating layer in the glycerin solution is preferably 0.15 kV / μm or more. Thus, by setting the dielectric breakdown voltage per unit thickness to the above lower limit or more, high insulating characteristics can be exhibited without excessively thickening the insulating layer.

The carbon concentration of the conductor peripheral surface is preferably 10% by mass or less. Thus, by making the carbon concentration of the conductor peripheral surface equal to or more than the above lower limit, the wire-drawing lubricant components (oil, surfactant, pH adjuster, etc.) that inhibit the adhesion between the conductor peripheral surface and the insulating layer are reduced. Therefore, the adhesion between the conductor peripheral surface and the insulating layer can be effectively improved.

It is preferable that the conductor peripheral surface is carbon-reduced. Thus, by performing a carbon reduction process with respect to a conductor surrounding surface, a wire drawing lubricant component is reduced and the high adhesive force of the above-mentioned conductor surrounding surface and an insulating layer is achieved.

As the carbon reduction treatment, a washing treatment using a liquid is preferable. By performing washing on the conductor, the wire drawing lubricant component adhering to the conductor peripheral surface can be effectively reduced, and the adhesion between the conductor peripheral surface and the insulating layer can be further improved.

It is preferable that the insulating layer has a primer layer which is laminated on the peripheral surface of the conductor and contains a phenoxy resin as a main component and a biphenyl-containing polyamideimide layer which contains a biphenyl-containing polyamideimide resin as a main component. By forming a primer layer containing phenoxy resin as a main component, adhesion between the conductor and the insulating layer can be improved, and scratch resistance can be improved. Furthermore, in addition to the primer layer, by forming a biphenyl-containing polyamideimide layer containing a biphenyl-containing polyamideimide resin as a main component, the mechanical strength of the insulating layer can be improved, and scratch resistance is further improved. Can do. The average thickness of the primer layer is preferably 0.5 μm or more and 5 μm or less. Even if the average thickness of the primer layer exceeds 5 μm, no decrease in adhesion is observed, but the primer layer mainly composed of phenoxy resin generally has a low heat softening temperature, so that mechanical properties and heat softening properties may be reduced. There is sex. As described above, the insulating layer has the primer layer and the biphenyl-containing polyamideimide layer, and the average thickness of the primer layer is within the above range, thereby further improving the adhesion between the conductor and the insulating layer. The strength of the insulating layer can be improved.

The above-mentioned biphenyl-containing polyamide-imide resin may contain a biphenyl-containing diisocyanate compound as an amide-imide raw material. Thus, the intensity | strength of the insulating layer which has a biphenyl containing polyamideimide layer can be improved easily and reliably by synthesize | combining a biphenyl containing polyamideimide resin using a biphenyl containing diisocyanate compound.

The insulating layer may further include another resin layer, and the other resin layer may contain a polyesterimide resin, a polyamideimide resin, or a polyimide resin as a main component. When the insulating layer has such another resin layer, the cost can be reduced while maintaining the function of the insulating layer of the insulated wire.

The peripheral surface of the insulating layer may further include a surface lubricating layer mainly composed of a polyamideimide resin containing a lubricant. By further providing such a surface lubricating layer, the friction coefficient of the insulated wire can be reduced. As a result, depending on the coil shape, the occurrence of scratches during coil production is suppressed, and the lineability during coil production is improved.

Moreover, another invention made in order to solve the said subject is:
A method for producing an insulated wire comprising a conductor mainly composed of aluminum or an aluminum alloy and an insulating layer covering a peripheral surface of the conductor,
Obtaining the conductor,
It has the process of performing a carbon reduction process with respect to the said conductor surrounding surface, and the process of coat | covering an insulating layer on the surrounding surface of the said conductor.

The above manufacturing method can improve the adhesion between the conductor peripheral surface and the insulating layer because the wire lubricant component that inhibits the adhesion between the conductor peripheral surface and the insulating layer is reduced by the carbon reduction treatment. As a result, the obtained insulated wire is excellent in adhesion, scratch resistance and insulating properties.

Here, “the average number of twists until the insulation layer is peeled off in the peel test” means the average value (number of samples: 3) of the values measured in accordance with the “peel test” defined in 5.4 of JIS-C3216-3 It is. However, when the nominal conductor diameter is less than 1 mm, the test load (tension) is 10N. “Average value of dielectric breakdown voltage per unit thickness of the insulating layer in the glycerin solution” means that a part of the insulated wire is immersed in a glycerin solution in which glycerin and saturated saline are mixed at a mass ratio of 17: 3. When the voltage is applied and the voltage is increased at a rate of 1 V / sec, the average voltage (number of samples: 10) at which the insulating layer is broken is divided by the average thickness of the insulating layer. “Carbon concentration” is a value measured using energy dispersive X-ray analysis (EDX).

As described above, the insulated wire of the present invention has high scratch resistance and insulating properties while using aluminum or an aluminum alloy as a conductor. Moreover, the manufacturing method of the insulated wire of this invention can manufacture the insulated wire excellent in adhesiveness, scratch resistance, and an insulation characteristic easily and reliably.

Hereinafter, embodiments of the insulated wire of the present invention will be described in detail.

The insulated wire includes a linear conductor and an insulating layer covering the peripheral surface of the conductor.

<Conductor>
The conductor is mainly composed of aluminum or an aluminum alloy. The aluminum alloy is not particularly limited, and a known aluminum alloy used for an insulated wire can be used. For example, a zirconium-containing alloy or an iron-containing alloy having high strength and excellent heat resistance can be used.

The cross-sectional shape of the conductor is not particularly limited, and various shapes such as a circle, a rectangle, and a rectangle can be adopted. Further, the size of the cross section of the conductor is not particularly limited. In the case of a round wire, one having a 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 conductor is subjected to a treatment for reducing carbon on the peripheral surface before the insulating layer is laminated. By this carbon reduction treatment, for example, organic substances such as a lubricant adhering during the wire drawing process can be removed, and the carbon component that inhibits the adhesion between the conductor and the insulating layer can be reduced.

The upper limit of the carbon concentration of the conductor peripheral surface is preferably 10% by mass, more preferably 7% by mass, and particularly preferably 5% by mass. When the carbon concentration of the conductor peripheral surface exceeds the above upper limit, the adhesion with the insulating layer may be reduced. For the same reason as the carbon concentration, the mass ratio of carbon to the mass of aluminum on the conductor peripheral surface is preferably 0.1 or less, and more preferably 0.06 or less. If the carbon concentration on the conductor peripheral surface or the mass ratio of aluminum is less than the above upper limit, the adhesion between the conductor and the insulating layer is improved, so the scratch resistance and flexibility of the insulated wire are also improved, and the processability to the coil is improved. Can be improved.

<Insulating layer>
The insulating layer is laminated on the peripheral surface of the conductor so as to cover the conductor. The insulating layer may be a single layer or a multilayer structure of two or more layers. When insulating materials (resins) having different characteristics are combined as a multilayer structure, different characteristics can be imparted to the inner layer, the outer layer, and the like.

The insulating layer of the insulated wire is preferably laminated on the peripheral surface of the conductor, for example, and the insulating layer is preferably laminated on the peripheral surface of the conductor and has a primer layer containing a flexible component such as phenoxy resin as a main component. . Furthermore, it is preferable to have a biphenyl-containing polyamideimide layer containing a biphenyl-containing polyamideimide resin as a main component in addition to the primer layer.

[Primer layer]
The primer layer contains a flexible component such as phenoxy resin or polyamideimide as a main component, and is formed by heat-treating a phenoxy resin varnish and a varnish containing the curing agent (this is a primer layer varnish). .

(Phenoxy resin)
The phenoxy resin used as the main component of the primer layer varnish is a resin having a large molecular weight among epoxy resins produced from a bisphenol compound and epihalohydrin, and usually has a weight average molecular weight (measured by GPC) of 30000- An epoxy resin of 100,000, preferably 50,000 to 80,000 is applicable.

Examples of the bisphenol compounds include 2,2-bis (p-hydroxyphenyl) propane (hereinafter referred to as “bisphenol A”), 2,2-bis (p-hydroxyphenyl) sulfone (hereinafter referred to as “bisphenol S”). , Bisphenol F, or a combination thereof. Depending on the type of bisphenol compound used, the heat resistance of the phenoxy resin having a bisphenol A skeleton (bisphenol A type phenoxy resin), the phenoxy resin having a bisphenol F skeleton (bisphenol F type phenoxy resin), and the bisphenol A type phenoxy resin In order to increase this, a phenoxy resin having a bisphenol S skeleton using 2,2-bis (p-hydroxyphenyl) sulfone (hereinafter referred to as “bisphenol S”) as a part of the bisphenol-based compound can be obtained. These bisphenol type phenoxy resins may be used alone or in combination of two or more.

Commercially available products may be used as the bisphenol type phenoxy resin as described above. Commercially available products of bisphenol A type phenoxy resin include, for example, manufactured by Toto Kasei Co., Ltd., product numbers YP-50, YP50S, YP-55, Epicoat manufactured by Japan Epoxy Resin Co., Ltd., Epicron manufactured by Dainippon Ink & Chemicals, Inc. PKHC, PKHH, PKHJ, etc. manufactured by Union Carbide Corporation are listed. As a commercial item of bisphenol S type phenoxy resin, the Toto Kasei Co., Ltd. product number YPS007A30A etc. are mentioned, for example. Commercially available products of bisphenol F type phenoxy resin include FX-316 manufactured by Toto Kasei Co., Ltd., 4010P, 4110, 4210 manufactured by Japan Epoxy Resin Co., Ltd. Furthermore, as commercial products of bisphenol A-type phenoxy resin and bisphenol F-type phenoxy resin or copolymer products, YP70 and ZX-1356-2 manufactured by Tohto Kasei Co., Ltd., 4250 and 4275 of Japan Epoxy Resin Co., Ltd. Etc.

In addition to the bisphenol-type phenoxy resin as described above, for example, a phenoxy resin obtained by reacting a hydroxyl group of dihydroxybiphenyl with epichlorohydrin to increase the molecular weight and having a biphenyl skeleton in the molecule can also be used. .

(Curing agent)
Since phenoxy resin has highly reactive epoxy groups and hydroxyl groups in the skeleton, insulation with excellent film strength and adhesion can be obtained by coexisting a curing agent that can react with these to form a crosslinked structure. A primer layer is formed from which a layer can be obtained. Examples of the curing agent include melamine compounds and isocyanate compounds, and these may be used alone or in combination.

Examples of the melamine compound include methylated melamine, butylated melamine, methylolated melamine, butyrolated melamine, and the like. These may be used alone or in combination of two or more. .

As the isocyanate compound, a blocked isocyanate in which an isocyanate group is protected with a blocking agent is preferably used. The blocked isocyanate compound is stable at room temperature, but regenerates a free isocyanate group when heated above its dissociation temperature. The dissociation temperature of the isocyanate depends on the type of the blocking agent, but is preferably 80 to 160 ° C, more preferably 90 to 130 ° C.

Examples of the isocyanate compound include aromatic diisocyanates such as tolylene diisocyanate (TDI), p-phenylene diisocyanate, and naphthalene diisocyanate; carbon numbers such as hexamethylene diisocyanate (HDI), 2,2,4-trimethylhexane diisocyanate, and lysine diisocyanate. 3 to 12 aliphatic diisocyanates; 1,4-cyclohexane diisocyanate (CDI), isophorone diisocyanate (IPDI), 4,4′-dicyclohexylmethane diisocyanate (hydrogenated MDI), methylcyclohexane diisocyanate, isopropylidene dicyclohexyl-4 , 4′-diisocyanate, 1,3-diisocyanatomerylcyclohexane (hydrogenated XDI), hydrogenated TDI, 2,5-bis (isocyanate) A cycloaliphatic diisocyanate having 5 to 18 carbon atoms such as til) -bicyclo [2.2.1] heptane, 2,6-bis (isocyanatomethyl) -bicyclo [2.2.1] heptane; (XDI), aliphatic diisocyanates having an aromatic ring such as tetramethylxylylene diisocyanate (TMXDI), and modified products of these diisocyanates.

Examples of the blocking agent that blocks the isocyanate group of these isocyanate compounds include alcohols such as methanol, ethanol, propanol, butanol, benzyl alcohol, and cyclohexanol, phenols, ε-caprolactam, and butyl cellosolves.

Commercially available products may be used as the blocked isocyanate as described above. For example, CT stable, BL-3175, TPLS-2759, BL-4165 manufactured by Sumika Bayer Urethane Co., Ltd., MS- manufactured by Nippon Polyurethane Industry Co., Ltd. 50 or the like can be used.

The curing agent as described above is used in a proportion of 3 to 60 parts by mass, preferably 5 to 50 parts by mass, more preferably 10 to 40 parts by mass per 100 parts by mass of the phenoxy resin from the viewpoint of improving the adhesion.

(Primer layer varnish)
The primer layer varnish contains a flexible component such as the above phenoxy resin, or contains a curing agent, and further, an epoxy resin, a polyesterimide resin, a polyamide, as necessary, as long as the object of the present invention is not hindered. Other resins such as imide resins; fillers such as silica, alumina, magnesium oxide, beryllium oxide, silicon carbide, titanium carbide, tungsten carbide, boron nitride, silicon nitride; to improve the curability and fluidity of varnish, for example , Tetraisopropyl titanate, tetrabutyl titanate, tetrahexyl titanate and other titanium compounds such as zinc naphthenates and zinc octenoates; antioxidants; anticorrosives; adhesion improvers; curability improvers; leveling agents; A resin composition containing additives such as auxiliaries is dissolved in an organic solvent. It is prepared.

Examples of the organic solvent include polar organics such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, tetramethylurea, hexaethylphosphoric triamide, and γ-butyrolactone. Solvents, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone; esters such as methyl acetate, ethyl acetate, butyl acetate, diethyl oxalate; diethyl esters, ethylene glycol dimethyl ether, diethylene glycol monomethyl ether, ethylene glycol Ethers such as monobutyl ether (butyl cellosolve), diethylene glycol methyl ether, tetrahydrofuran; hexane, heptane, benzene, toluene, xylene Hydrocarbon compounds such as dichloromethane and chlorobenzene; phenols such as cresol and chlorophenol; tertiary amines such as pyridine and the like. These organic solvents may be used alone or in combination of two or more. It can be used by mixing.

A primer layer can be formed by directly applying a varnish for a primer layer having the above composition to an aluminum conductor and baking it. The baking temperature is preferably a temperature at which the phenoxy resin can be thermally cured by reacting with a curing agent, and is usually about 200 to 600 ° C. Moreover, application | coating and baking of a varnish may be performed only once and may be performed twice or more.

The average thickness of the primer layer formed as described above is preferably 0.5 μm to 5 μm, and more preferably 1 μm to 3 μm. When the average thickness of the primer layer is less than the above lower limit, the effect of forming the primer layer may be difficult to obtain. In addition, the ratio of the maximum thickness to the minimum thickness in the circumferential direction and the longitudinal direction also increases in manufacturing the winding, which may cause variations in various characteristics. On the other hand, even if the average thickness of the primer layer exceeds the above upper limit, there is no decrease in adhesion, but a flexible primer such as phenoxy resin generally has a low heat softening temperature, so mechanical properties and heat softening properties may be reduced. There is sex. Moreover, there exists a possibility that it may become disadvantageous in cost.

[Biphenyl-containing polyamideimide layer]
The biphenyl-containing polyamide-imide layer refers to a cured product layer formed using a polyamide-imide varnish using a biphenyl-containing diisocyanate as part of an isocyanate compound that is an amide imide raw material. Since a biphenyl group derived from a biphenyl-containing diisocyanate is contained, the strength is improved as compared with a cured product of a polyamideimide varnish (a general-purpose polyamideimide varnish) that does not use a biphenyl-containing compound as a raw material.

Here, as the amide-imide raw material, an amine compound is further used when synthesizing a polyamide-imide by reacting an isocyanate compound and a carboxylic acid, or an imide dicarboxylic acid, which is a reaction product of an amine compound and an acid, with an isocyanate. It is done. The varnish for biphenyl-containing polyamideimide layer is characterized in that biphenyl-containing diisocyanate is used as a part of the isocyanate compound used as a raw material.

As the above-mentioned biphenyl-containing diisocyanate compound, typically 3,3′-dimethylbiphenyl-4,4′-diisocyanate is preferably used. In addition, biphenyl-4,4′-diisocyanate, biphenyl-3,3′-diisocyanate are used. Biphenyl-3,4'-diisocyanate, 3,3'-dichlorobiphenyl-4,4'-diisocyanate, 2,2'-dichlorobiphenyl-4,4'-diisocyanate, 3,3'-dibromobiphenyl-4, 4'-diisocyanate, 2,2'-dibromobiphenyl-4,4'-diisocyanate, 3,3'-dimethylbiphenyl-4,4'-diisocyanate, 2,2'-dimethylbiphenyl-4,4'-diisocyanate, 2,3'-dimethylbiphenyl-4,4'-diisocyanate 3,3'-diethylbiphenyl-4,4'-diisocyanate, 2,2'-diethylbiphenyl-4,4'-diisocyanate, 3,3'-dimethoxybiphenyl-4,4'-diisocyanate, 2,2 '-Dimethoxybiphenyl-4,4'-diisocyanate, 2,3'-dimethoxybiphenyl-4,4'-diisocyanate, 3,3'-diethoxybiphenyl-4,4'-diisocyanate, 2,2'-diethoxy Biphenyl-4,4'-diisocyanate, 2,3'-diethoxybiphenyl-4,4'-diisocyanate and the like can be mentioned.

As the isocyanate compound other than the biphenyl-containing diisocyanate compound, a diisocyanate compound as used in a normal polyamide-imide varnish can be used, and diphenylmethane-4,4′-diisocyanate, diphenylmethane-3,3′-diisocyanate, diphenylmethane-3 , 4'-diisocyanate, diphenyl ether-4,4'-diisocyanate, benzophenone-4,4'-diisocyanate, diphenylsulfone-4,4'-diisocyanate, tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, Aromatic diisocyanates such as naphthylene-1,5-diisocyanate, m-xylylene diisocyanate, and p-xylylene diisocyanate are preferably used.

Furthermore, in order to increase the crosslinking density of the biphenyl-containing polyamideimide layer, a polyfunctional polyisocyanate compound can be used as a part of the isocyanate compound as an amideimide raw material. Examples of polyfunctional polyisocyanates include polyisocyanates that are trimers of triphenylmethane triisocyanate, diphenyl ether triisocyanate, and diisocyanate compounds (trade names Desmodur L, Desmodur AP, etc. from Sumika Bayer Urethane Co., Ltd.), polymethylene poly Examples thereof include phenyl isocyanate.

Among the isocyanate compounds used as the raw material, the content ratio of the biphenyl-containing diisocyanate compound is preferably 10 to 80 mol%. If it is less than 10 mol%, the effect of increasing the strength of the resulting biphenyl-containing polyamideimide film will be insufficient.

Examples of carboxylic acids include trimellitic anhydride, trimellitic acid chloride, and trimellitic acid anhydrides such as tribasic acids; tetracarboxylic acid anhydrides and dibasic acids such as pyromellitic dianhydride , Biphenyltetracarboxylic dianhydride, benzophenonetetracarboxylic dianhydride, diphenylsulfonetetracarboxylic dianhydride, terephthalic acid, isophthalic acid, sulfoterephthalic acid, dicitric acid, 2,5-thiophenedicarboxylic acid, 4, Dicarboxylic acids such as 5-phenanthenedicarboxylic acid, benzophenone-4,4'-dicarboxylic acid, phthaldiimide dicarboxylic acid, biphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, adipic acid Trimellitic acid, pyromellitic acid, Tan tetracarboxylic acid, biphenyl tetracarboxylic acid, benzophenone tetracarboxylic acid, can be used polycarboxylic acids such as diphenylsulfone tetracarboxylic acid. These can be used alone or in combination of two or more.

A polyfunctional polyisocyanate or polyfunctional carboxylic acid containing three or more isocyanate groups or carboxyl groups is preferable from the viewpoint of heat resistance because it can increase the crosslinking density of the polyamideimide film. The content of the polyfunctional polyisocyanate and the polyfunctional carboxylic acid is such that the total content of the polyisocyanate compound and / or the polycarboxylic acid compound is 0.5 to 8 mol% with respect to the total amount of the isocyanate component and the acid component. Is preferably 0.5 to 3 mol%. If it is less than 0.5 mol%, a sufficient crosslinked structure cannot be obtained, and if it exceeds 8 mol%, the crosslinking density is too high and the flexibility of the insulating layer tends to be inferior.

As described above, an approximately equimolar amount of an isocyanate component and an acid component containing the polyisocyanate compound and / or the polycarboxylic acid compound in the above proportions are added in an appropriate organic solvent at a temperature of 0 to 180 ° C. More specifically, after 24 hours, more specifically, heating at a temperature of less than 140 ° C. for a certain period of time, then raising the temperature and further reacting by heating for a certain period of time, it is a copolymer of an isocyanate component and an acid component. A polyamideimide varnish in which polyamideimide is dissolved or dispersed in an organic solvent is obtained.

In the case of a polyamide-imide varnish obtained by reacting an amine component and an acid component to obtain an imide dicarboxylic acid and reacting the imide dicarboxylic acid and an isocyanate component, in addition to the acids and diisocyanate compounds listed above as amine amide raw materials, an amine Ingredients included. In this case, the polycarboxylic acid and / or the polyisocyanate is adjusted so that the total content of the polycarboxylic acid compound and the polyisocyanate compound is 0.5 to 8 mol% with respect to the total amount of the amine component, the acid component, and the isocyanate component. Is contained.

As the diamine compound, an aromatic diamine having an aromatic ring in the structure is particularly preferably used. Examples of the aromatic diamine include 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodibenzophenone, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylhexafluoropropane, 4,4 '-[bis (4-aminophenoxy )] Biphenyl, 4,4 '-[bis (4-aminophenoxy)] diphenyl ether, 4,4'-[bis (4-aminophenoxy)] diphenyl sulfone, 4,4 '-[bis (4-aminophenoxy) Diphenylmethane, 4,4 '-[bis (4-aminophenoxy)] di Enirupuropan, 4,4' [bis (4-aminophenoxy)] diphenyl hexafluoropropane, etc., various diamine compounds conventionally known may be mentioned.

In addition, benzidine, 3-methyl-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,3'-dimethyl-4,4'-diaminobiphenyl, 2,2 '-Dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethyl-3,4'-diaminobiphenyl, 3,3'-dimethyl-3,3'-diaminobiphenyl, 3,3'-diethyl-4 , 4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-diethoxy-4,4'-diaminobiphenyl, 3,3'-dichloro-4,4'-diamino Biphenyl, 3,3′-dibromo-4,4′-diaminobiphenyl, and the like can also be mixed and used.

By reacting an amine component and an acid component as described above in an approximately stoichiometric amount in an organic solvent to form imidodicarboxylic acid, and copolymerizing it with an approximately stoichiometric amount of an isocyanate component, biphenyl is obtained. A containing polyamideimide resin can be produced. More specifically, when an acid component and an amine component of about 1/2 mole amount thereof are reacted in a suitable organic solvent at a temperature of 0 to 150 ° C. for 1 to 24 hours, the reaction between the amine component and the acid component is performed. The product, imidodicarboxylic acid, is generated in the reaction solution. Next, when an approximately equimolar amount of an isocyanate component is added to the reaction liquid and reacted at a temperature of 0 to 150 ° C. for 1 to 24 hours, the biphenyl-containing polyamideimide is dissolved in the organic solvent or A dispersed biphenyl-containing polyamideimide varnish is obtained.

In addition, the biphenyl-containing polyamide-imide varnish may contain various additives as mentioned in the primer layer varnish, if necessary. Moreover, as an organic solvent, the organic solvent as mentioned in the varnish for primer layers can be used.

As the polyamide-imide varnish for forming the biphenyl-containing polyamide-imide layer as described above, for example, a polyamide-imide varnish as disclosed in Japanese Patent No. 3497525 can be used.

The biphenyl-containing polyamideimide layer is composed of a cured product of the polyamideimide varnish as described above, and may be formed on the primer layer, or on the other resin layer via the other resin layer on the primer layer. It may be formed. A biphenyl-containing polyamideimide layer is formed by applying and baking a biphenyl-containing polyamideimide varnish. The baking temperature is usually about 200 to 600 ° C. Moreover, application | coating and baking of a varnish may be performed only once and may be performed in multiple times.

The thickness of the biphenyl-containing polyamideimide layer may be at least 0.5 μm, and is appropriately selected within a range of about 50 μm at the maximum depending on the presence of other resin layers and the size of the insulated wire.

[Other resin layers]
The insulating layer of the insulated wire may have a resin layer other than the primer layer and the biphenyl-containing polyamideimide layer.

When the insulating layer has a structure of three or more layers including a primer layer, a biphenyl-containing polyamideimide layer, and another resin layer, the other resin layer is interposed between the primer layer and the biphenyl-containing polyamideimide layer. Alternatively, a biphenyl-containing polyamideimide layer may be formed on the primer layer, another resin layer may be formed on the biphenyl-containing polyamideimide layer, and biphenyl-containing polyamide may be formed between two other resin layers. An insulating layer having a structure in which an imide layer is interposed may be used.

The varnish used for forming the other resin layers is not particularly limited, and is a general-purpose type polyamideimide resin, polyesterimide resin, polyimide resin, polyurethane resin, polyester conventionally used as a coating for insulated wires. It is possible to use a varnish mainly composed of a resin, a polyamide resin, an epoxy resin or the like. By applying and baking these varnishes by a conventionally known method, depending on the type of varnish, a general-purpose type polyamideimide layer, polyesterimide layer, polyimide layer, polyester layer, polyamide layer, epoxy resin layer, etc. A resin layer is formed.

When other resin layers are included, the thickness ratio of the other resin layers in the insulating layer is preferably about 0 to 80%, more preferably about 0 to 50% with respect to the thickness of the insulating layer. If it exceeds 80%, the ratio of the biphenyl-containing polyamideimide layer decreases, so that it is difficult to obtain the effect (improvement of mechanical strength).

[Surface lubrication layer]
The insulated wire may further have a coating (surface lubricating layer) having lubricity on the peripheral surface of the insulating layer from the viewpoint of reducing the friction of the winding. The resin constituting the surface lubrication layer may be any resin having lubricity, for example, paraffins such as liquid paraffin and solid paraffin, various waxes, polyethylene, fluororesin, silicone resin and other lubricants with a binder resin. There may be mentioned a bound one. Preferably, a polyamide-imide resin imparted with lubricity by adding paraffin or wax is used.

The thickness of the surface lubrication layer is not particularly limited, but may be any thickness that is necessary and sufficient to reduce friction and wear with surrounding insulated wires and coil forming jigs when it is a coil. Is preferably 0.5 μm to 10 μm, and more preferably 1 μm to 5 μm.

Although it does not specifically limit as average thickness of the whole insulating layer, For example, they can be 20 micrometers or more and 100 micrometers or less.

<Insulated wire>
The insulated wire has an average number of twists of 50 or more until peeling of the insulating layer in the peel strength test. The lower limit of the average number of twists until the insulating layer is peeled is more preferably 60 times. When the average number of twists until peeling is less than the above lower limit, the adhesion between the conductor and the insulating layer is not sufficient, so that the scratch resistance of the insulated wire cannot be obtained.

The lower limit of the average value of the dielectric breakdown voltage per unit thickness of the insulating layer in the glycerin solution of the insulated wire is preferably 0.15 kV / μm, and more preferably 0.20 kV / μm. On the other hand, the upper limit of the average value of the dielectric breakdown voltage per unit thickness of the insulating layer is preferably 0.27 kV / μm. When the dielectric breakdown voltage is less than the lower limit, the insulated wire may not be used for equipment used under high voltage. Moreover, when a dielectric breakdown voltage exceeds the said upper limit, when manufacturing the said insulated wire stably, there exists a possibility of causing a raise of cost.

The lower limit of the scratching load of the insulated wire is preferably 3.5 kgf, more preferably 4.0 kgf, and particularly preferably 3.8 kgf. When the scratching load is less than the above lower limit, there is a possibility that the insulating property may be deteriorated by scratching the insulated wire or peeling off the insulating layer when the coil is processed. The scratching load is a load when a pinhole is generated in the insulating layer when a piano wire is overlapped at right angles to the insulated wire and the insulated wire is pulled out with the load applied to the intersection.

<Insulated wire manufacturing method>
The insulated wire can be easily and reliably manufactured by a manufacturing method having the following steps.
(1) Conductor manufacturing process for obtaining a conductor (2) Carbon reduction process for performing carbon reduction treatment on the conductor peripheral surface (3) Coating process for covering the peripheral surface of the conductor with an insulating layer

<(1) Conductor manufacturing process>
In the conductor manufacturing process, first, aluminum or an aluminum alloy as a raw material for a conductor is cast and rolled to obtain a rolled material. Next, this rolled material is subjected to wire drawing to form a wire drawing material having an arbitrary cross-sectional shape and wire diameter (short side width). As a method of wire drawing, for example, by using a wire drawing device equipped with a plurality of wire drawing dies, a rolled material coated with a lubricant is inserted into the wire drawing dies, thereby obtaining a desired cross-sectional shape and wire diameter (short side width). ) Can be used. As the wire drawing die, a wire drawing die, a roller die, or the like can be used. Further, as the lubricant, water-soluble and water-insoluble ones containing an oil component can be used. Note that the cross-sectional processing can be performed separately after softening.

After the wire drawing, the wire drawing material is softened by heating. Since the crystal of the wire drawing material is recrystallized by performing the softening treatment, the toughness of the conductor can be improved. As heating temperature in a softening process, it can be set as 250 degreeC or more, for example.

The softening treatment can be performed in an air atmosphere, but is preferably performed in a non-oxidizing atmosphere with a low oxygen content. Thus, by performing a softening process in a non-oxidizing atmosphere, the oxidation of the surrounding surface of a wire drawing material during a softening process (heating) can be suppressed. Examples of the non-oxidizing atmosphere include a vacuum atmosphere, an inert gas atmosphere such as nitrogen and argon, and a reducing gas atmosphere such as a hydrogen-containing gas and a carbon dioxide-containing gas.

Softening treatment can be continuous or batch. As a continuous method, for example, a furnace type in which a wire drawing material is introduced into a heating container such as a pipe furnace and heated by heat conduction, a direct current method in which a wire drawing material is energized and heated by resistance heat, and the wire drawing material is subjected to high-frequency electromagnetic waves. And an indirect energization method in which heating is performed. Among these, a furnace type that allows easy temperature control is preferable. Examples of the batch method include a method in which a wire drawing material is enclosed in a heating container such as a box furnace and heated. The heating time of the batch method can be set to 0.5 hours or more and 6 hours or less. In the batch method, the structure can be further refined by rapid cooling at a cooling rate of 50 ° C./sec or more after heating.

<(2) Carbon reduction process>
In the carbon reduction step, a carbon reduction treatment is performed on the peripheral surface of the conductor obtained in the conductor manufacturing step. By performing the carbon reduction treatment in this manner, organic substances such as a lubricant attached during the wire drawing process can be removed, and the adhesion between the conductor and the insulating layer can be improved.

Specific examples of the carbon reduction treatment include a cleaning method, a decomposition method, and a physical removal method.

As the above cleaning method, for example, immersion cleaning, spray cleaning, steam cleaning, brushing cleaning, electrolytic cleaning, ultrasonic cleaning, micro bubbling with fine bubbles, or the like can be used. Examples of the cleaning agent used in this cleaning method include solvents such as water, petroleum-based solvents, aromatic hydrocarbons, halogenated hydrocarbons, polar group-containing solvents (ketones, alcohols, etc.), emulsions composed of these, and surface active agents for these. Neutral liquids such as solutions in which agents are dissolved; acidic liquids such as aqueous solutions of inorganic acids (hydrochloric acid, nitric acid, sulfuric acid, chromic acid, etc.), aqueous solutions of organic acids (formic acid, acetic acid, etc.); inorganic alkalis (sodium hydroxide, carbonic acid, etc.) Examples thereof include alkaline liquids such as aqueous solutions of sodium hydrogen and the like, and aqueous solutions of organic alkalis (such as ethanolamine).

As the decomposition method, for example, an ultraviolet irradiation method, a plasma treatment method, a baking method, or the like can be used.

As the physical removal method, for example, wiping, brushing, centrifugation, vibration, air washing, or the like can be used.

The above various methods can be used in combination. However, electrolytic cleaning using acidic liquid or alkaline liquid, especially in the case of aluminum conductors with small diameters, causes deterioration of adhesion, deterioration of electrical characteristics, linear fluctuation, etc. due to precipitation of impurities on the peripheral surface. However, the suitability for mass production may be reduced. Further, since a wire drawing lubricant containing a large amount of mineral oil is used in the wire drawing process of the aluminum conductor, it is difficult to obtain a sufficient effect with a single cleaning. Therefore, it is preferable to perform a plurality of washings using a neutral liquid. For example, after the conductor is immersed and cleaned with a detergent containing a surfactant, the peripheral surface of the aluminum conductor after the wire drawing step is further performed by immersion cleaning using water, ultrasonic cleaning using water, or both. The lubricant containing a lot of mineral oil adhering to the surface can be effectively removed, and the carbon removal effect can be enhanced. In addition, the carbon removal effect can be enhanced by high-temperature cleaning or long-time cleaning. Since these cleaning methods can be continuously performed in-line in the manufacturing process of the insulated wire, they contribute to the improvement of the productivity of the insulated wire.

In addition, when an acidic liquid or alkaline liquid is used for cleaning, not only cleaning but also roughening due to dissolution of the aluminum conductor may be actively generated. By roughening the aluminum conductor, the contact area between the aluminum conductor and the insulating layer can be increased to improve adhesion.

<(3) Coating process>
In the covering step, an insulated wire is obtained by laminating an insulating layer on the conductor subjected to the carbon reduction treatment. Specifically, the insulating layer is formed by applying a paint (varnish) obtained by dissolving a resin for forming the insulating layer in an organic solvent to the peripheral surface of the conductor and baking it.

As a method of applying the varnish to the conductor peripheral surface, for example, a method using a coating apparatus including a varnish tank storing the varnish and a coating die can be used. According to this coating apparatus, the varnish adheres to the peripheral surface of the conductor as the conductor passes through the varnish tank, and then the varnish is applied to a substantially uniform thickness by passing through the coating die. In addition, as content of the resin in a varnish, 10 to 50 mass% is preferable.

As a method of heating and baking the varnish, for example, a method of indirectly heating the conductor using a cylindrical heating furnace long in the running direction of the conductor can be used. Although this heating method is not specifically limited, It can carry out by well-known methods, such as hot air heating, infrared heating, induction heating. By such heating, the solvent contained in the varnish applied to the conductor peripheral surface is vaporized, and the conductor peripheral surface is coated with the resin. The heating temperature is appropriately selected depending on the type of resin used for the insulating layer.

By running the conductor in the coating apparatus and the heating furnace a plurality of times, the coating and baking can be repeated a plurality of times to increase the thickness of the resin film. At this time, the hole diameter of the coating die is adjusted to gradually increase as necessary according to the number of repetitions. When a resin film having a predetermined thickness is obtained, an insulating layer composed of a plurality of layers having different main components can be formed by changing the resin component contained in the varnish and continuing the coating process. In addition, although the repetition frequency of application | coating and baking for each layer can be selected suitably, 2 to 20 times is suitable.

<Coil>
Since the said insulated wire uses aluminum or aluminum alloy as a conductor, it is excellent in lightweight property, and also as mentioned above, it is excellent in scratch resistance and insulation characteristics. Therefore, the coil which can be used suitably for various uses can be obtained by winding the said insulated wire.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

In addition, each measured value in a present Example is a value measured with the following method.

[Number of twists until insulation layer peeling (unit: times)]
Based on the “peeling test” specified in 5.4 of JIS-C3216-3, the number of twists until the insulating layer was peeled was measured, and the average value of 10 times was obtained. Hereinafter, one test will be described. First, using a scraper, the upper and lower coating portions of the insulated wire are removed so that the conductors are exposed, and a test piece is prepared. Next, one end of this test piece was fixed, the other end was twisted in one direction with a constant load, and the number of twists until the insulating layer on the remaining side surface part was lifted was measured.

[Dielectric breakdown voltage (unit: kV / μm)]
A test piece (length 120 mm, twist number 18) in which two insulated wires were twisted was produced. A part of this test piece was immersed in a test solution in which glycerin and saturated saline were mixed at a mass ratio of 17: 3, and an alternating voltage was applied between one end of the test piece and the test solution. The voltage when the AC voltage is boosted at a rate of 1 V / sec and shorted is measured as the breakdown voltage, and the average breakdown voltage of the 10 test pieces is divided by the average thickness of the insulating layer of the insulated wire. The calculated value was calculated.

[Scratching load (unit: kgf)]
A piano wire was superimposed at right angles to the insulated wire, and when the insulated wire was pulled out with a load applied to the intersection, the load when a pinhole was generated in the insulating layer was measured. The load was started from 2 kgf and increased by 0.5 kgf. The occurrence of pinholes is in accordance with the “pinhole test” specified in 7 of JIS-C3216-5, and the above-mentioned scratch is applied to 2 g / L saline solution with an appropriate amount of 30 g / L phenolphthalein alcohol solution added. It confirmed by immersing a part of insulated wire after a test, and applying the DC voltage of 12V for 1 minute between the end of an insulated conductor, and salt solution. In this application test, the saline solution around the location where the pinhole is generated turns pink, so that the presence or absence of the pinhole can be confirmed by confirming the color change. The test was performed on eight test specimens of insulated wires, and the load in the case where even one pinhole was recognized was defined as a scratch load.

[Carbon concentration on conductor circumference (unit: mass%)]
The carbon concentration of the conductor peripheral surface before laminating the insulating layer was measured by energy dispersive X-ray analysis (EDX). The measurement conditions were an acceleration voltage of 5 kV, an emission current of 100 to 120 μA, an analysis area of 0.4224 mm × 0.3300 mm, and a full-scale count (CPS) of about 1000.

[Mass ratio of carbon to aluminum on the conductor circumference]
The aluminum concentration of the conductor peripheral surface was measured by the energy dispersive X-ray analysis method, and the carbon concentration of the conductor peripheral surface was divided by this aluminum concentration to obtain the mass ratio of carbon to aluminum on the conductor peripheral surface.

[Elastic modulus of resin (unit: GPa)]
Only the resin part was taken out from the insulated wire and measured by a dynamic viscoelasticity measurement method (DMS). The measurement conditions were a frequency of 1 Hz, a strain of 5 μm, and a storage elastic modulus calculated from a tensile stress when the temperature was raised at a rate of temperature increase of 10 ° C./min in a nitrogen stream was defined as an elastic modulus.

[Example 1]
Aluminum was cast, drawn, drawn and softened to obtain a conductor having a circular cross section and a diameter of 1 mm. This conductor is immersed in a cleaning liquid storage tank A storing a cleaning liquid containing a surfactant (“Exemlite DS-336” manufactured by Kyoeisha Chemical Co., Ltd., cleaning agent A in the table), and then distilled water storing distilled water. It was immersed in the storage tank B, and further ultrasonic cleaning was performed in an ultrasonic tank C storing distilled water to reduce carbon on the conductor peripheral surface. The peripheral surface carbon concentration of this conductor was 3.5% by mass, and the mass ratio of carbon to the mass of aluminum on the peripheral surface of the conductor was 0.04. As a lubricant at the time of wire drawing, Farbest Kasei Co., Ltd. “Super Draw 450” was used.

After the carbon reduction treatment, an insulating layer was coated by applying and baking a resin varnish on the peripheral surface of the conductor to obtain an insulated wire of Example 1. The insulating layer is made of polyesterimide (“Isomid40SM-45” manufactured by Hitachi Chemical Co., Ltd., “general purpose EsI” in the table) and 29.5 μm thick innermost layer, and general purpose polyamideimide (“general purpose AI” in the table). ) And an outer layer having a thickness of 4.5 μm and formed from a highly lubricious polyamideimide (“Lubrication AI” in the table). Among these, the elastic modulus of the resin obtained by baking the general-purpose EsI varnish in the coating step was 1.9 GPa at 50 ° C. and 0.46 GPa at 200 ° C.

The general-purpose polyamideimide used for the intermediate layer was prepared by the following method. First, anhydrous Trimerit while flowing 150 mL of nitrogen gas from a nitrogen blowing tube into a 1 L flask equipped with a thermometer, a cooling tube, a calcium chloride filling tube, a stirrer and a nitrogen blowing tube. 143.6 g of acid and 193.8 g of 4,4′-diphenylmethane diisocyanate (“Cosmonate PH” manufactured by Mitsui Takeda Chemical Co., Ltd.) were added. Next, 536 g of N-methyl-2-pyrrolidone was added as a solvent in the flask, and the mixture was heated at 80 ° C. for about 3 hours while stirring with a stirrer. Then, the temperature in the flask was increased to 120 ° C. over about 4 hours. The temperature was raised and the mixture was heated at this temperature for about 3 hours. Thereafter, the heating was stopped, 134 g of xylene was added to the flask to dilute the content liquid, and then allowed to cool to obtain a general-purpose polyamideimide resin varnish.

Further, the highly lubricious polyamideimide used for the outermost layer was prepared by the following method. A highly lubricious polyamideimide resin varnish was obtained by mixing polyethylene wax in a ratio of 1.5 parts by mass with 100 parts by mass of the solid content of the general-purpose polyamideimide in the general-purpose polyamideimide prepared by the above method.

[Example 2]
After obtaining an aluminum conductor by the same process as in Example 1 and immersing this conductor in the cleaning liquid storage tank A, the immersion cleaning in the distilled water storage tank B is not performed, but the ultrasonic cleaning is performed in the ultrasonic tank C as it is. Went. The peripheral surface carbon concentration of this conductor was 4.5% by mass, and the mass ratio of carbon to aluminum on the peripheral surface of the conductor was 0.05. The insulating layer similar to Example 1 was laminated | stacked on this conductor surrounding surface, and the insulated wire of Example 2 was obtained.

[Example 3]
An aluminum conductor was obtained by the same process as in Example 1, and this conductor was immersed in the cleaning liquid storage tank A and then immersed in the distilled water storage tank B. The ultrasonic cleaning in the ultrasonic tank C was not performed. The peripheral surface carbon concentration of this conductor was 6.3% by mass, and the mass ratio of carbon to aluminum on the peripheral surface of the conductor was 0.07. The insulating layer similar to Example 1 was laminated | stacked on this conductor surrounding surface, and the insulated wire of Example 3 was obtained.

[Example 4]
An aluminum conductor was obtained by the same process as in Example 1, and the conductor peripheral surface was formed in the same procedure as in Example 1 except that “Cerfa-Kleen 5395” (cleaning agent B in the table) manufactured by Horton Co., Ltd. was used as the surfactant. Washed. The circumferential surface carbon concentration of this conductor was 4.5% by mass. The insulating layer similar to Example 1 was laminated | stacked on this conductor surrounding surface, and the insulated wire of Example 4 was obtained.

[Example 5]
An aluminum conductor was obtained by the same process as in Example 1, and the peripheral surface of the conductor was formed in the same procedure as in Example 3 except that “Cerfa-Kleen 5395” (cleaning agent B in the table) manufactured by Horton Co., Ltd. was used as the surfactant. Washed. The peripheral surface carbon concentration of this conductor was 9.6% by mass. The insulating layer similar to Example 1 was laminated | stacked on this conductor surrounding surface, and the insulated wire of Example 5 was obtained.

[Example 6]
An aluminum conductor was obtained by the same process as in Example 1, and the same procedure as in Example 3 was used except that “NS Clean 200” (cleaning agent C in the table) manufactured by JX Nippon Oil & Energy was used as the surfactant. The conductor peripheral surface was cleaned. The circumferential surface carbon concentration of this conductor was 4.3% by mass. The insulating layer similar to Example 1 was laminated | stacked on this conductor surrounding surface, and the insulated wire of Example 6 was obtained.

[Example 7]
An aluminum conductor is obtained by the same process as in Example 1, and this conductor is a cleaning liquid storage tank A in which a cleaning liquid containing a surfactant (“NS Clean 200” manufactured by JX Nippon Mining & Energy Co., Ltd., cleaning agent C in the table) is stored. Soaked. The immersion in the distilled water storage tank B and the ultrasonic cleaning in the ultrasonic tank C were not performed. The circumferential surface carbon concentration of this conductor was 4.4% by mass. The insulating layer similar to Example 1 was laminated | stacked on this conductor surrounding surface, and the insulated wire of Example 7 was obtained.

[Comparative Example 1]
An aluminum conductor was obtained by the same process as in Example 1, but the peripheral surface cleaning (carbon reduction treatment) was not performed on this conductor. The peripheral surface carbon concentration of this conductor was 13.0% by mass, and the mass ratio of carbon to aluminum on the peripheral surface of the conductor was 0.15. The insulating layer similar to Example 1 was laminated | stacked on this conductor surrounding surface, and the insulated wire of the comparative example 1 was obtained.

[Comparative Example 2]
An aluminum conductor was obtained by the same process as in Example 1, and this conductor was immersed in the distilled water storage tank B. The immersion in the cleaning liquid storage tank A and the ultrasonic cleaning in the ultrasonic tank C were not performed. The peripheral surface carbon concentration of this conductor was 12.9% by mass, and the mass ratio of carbon to aluminum on the peripheral surface of the conductor was 0.18. The insulating layer similar to Example 1 was laminated | stacked on this conductor surrounding surface, and the insulated wire of the comparative example 2 was obtained.

[Comparative Example 3]
An aluminum conductor was obtained by the same process as in Example 1, and this conductor was immersed in the cleaning liquid storage tank A. The immersion in the distilled water storage tank B and the ultrasonic cleaning in the ultrasonic tank C were not performed. The peripheral surface carbon concentration of this conductor was 11.5% by mass, and the mass ratio of carbon to aluminum on the peripheral surface of the conductor was 0.13. The insulating layer similar to Example 1 was laminated | stacked on this conductor surrounding surface, and the insulated wire of the comparative example 3 was obtained.

[Comparative Example 4]
An aluminum conductor was obtained by the same process as in Example 1, and this conductor was subjected to ultrasonic cleaning in the ultrasonic bath C. The immersion in the cleaning liquid storage tank A and the distilled water storage tank B was not performed. The peripheral surface carbon concentration of this conductor was 12.5% by mass. The insulating layer similar to Example 1 was laminated | stacked on this conductor surrounding surface, and the insulated wire of the comparative example 4 was obtained.

[Examples 8 to 13]
An aluminum conductor was obtained by the same process as in Example 1, and this conductor was treated with water vapor at the temperature shown in Table 2 for the time shown in Table 2 to clean the surface. The peripheral carbon concentrations of these conductors were the values shown in Table 2, respectively. An insulating layer similar to that of Example 1 was laminated on these conductor peripheral surfaces to obtain insulated wires of Examples 8 to 13.

[Comparative Example 5]
An aluminum conductor was obtained by the same process as in Example 1, and the surface was immersed in water at 26 ° C. for 4 seconds to clean the surface. The peripheral carbon concentration of this conductor was 13.2% by mass. The insulating layer similar to Example 1 was laminated | stacked on this conductor surrounding surface, and the insulated wire of the comparative example 5 was obtained.

[Comparative Examples 6 and 7]
An aluminum conductor was obtained by the same process as in Example 1, and the surface was washed by spraying water at a pressure shown in Table 2 for 4 seconds at a pressure of 10 MPa. The peripheral carbon concentrations of these conductors were the values shown in Table 2, respectively. The insulating layers similar to those of Example 1 were laminated on the peripheral surfaces of these conductors, and the insulated wires of Comparative Examples 6 and 7 were obtained.

[Comparative Examples 8 and 9]
An aluminum conductor was obtained by the same process as in Example 1, and this conductor was treated with water vapor at the temperature shown in Table 2 for the time shown in Table 2 to clean the surface. The peripheral carbon concentrations of these conductors were the values shown in Table 2, respectively. The insulating layers similar to those of Example 1 were laminated on the conductor peripheral surfaces to obtain insulated wires of Comparative Examples 8 and 9.

[Examples 14 to 23]
An aluminum conductor was obtained by the same process as in Example 1, and the conductor peripheral surface was washed in the same procedure as in Example 1. An insulating layer having the configuration shown in Table 3 was laminated on the circumferential surface of the conductor to obtain insulated wires of Examples 14 to 23.

[Examples 24-32]
After obtaining an aluminum conductor by the same process as in Example 1 and immersing this conductor in a cleaning liquid storage tank A storing a cleaning liquid containing a surfactant (“Exemlite DS-336” manufactured by Kyoeisha Chemical Co., Ltd.), The conductor peripheral surface was cleaned by immersing in distilled water storage tank B storing distilled water, and further performing ultrasonic cleaning in ultrasonic tank C storing distilled water. The circumferential surface carbon concentration of this conductor was 3.4% by mass. An insulating layer having the structure shown in Table 3 was laminated on the peripheral surface of the conductor to obtain insulated wires of Examples 24 to 32.

The insulating layer constituting resin used in Examples 14 to 32 (Table 3) will be described below.

“Phenoxy 1” in the table means bisphenol A-modified phenoxy resin, and a varnish was obtained by the following procedure. “Toyo Kasei Co., Ltd.“ YP-50 ”(epoxy equivalent 87600 g / eq based on JIS K7236, weight average molecular weight 60000-80000 by GPC, glass transition point 84 ° C. by DSC method (10 ° C./min increase)) / A solution (solid content: 27% by mass) dissolved in cyclohexanone was used. A varnish for a primer layer was prepared by mixing 20 parts by mass of MS50 (manufactured by Nippon Polyurethane Industry) as a blocked isocyanate with 100 parts by mass of a bisphenol A-modified phenoxy resin. The solid content in the varnish is 27% by mass. The elastic modulus of the resin obtained by baking this resin varnish in the coating step was 1.6 GPa at 50 ° C. and 0.017 GPa at 200 ° C.

“Phenoxy 2” in the table means bisphenol A-modified phenoxy resin, and a varnish was obtained by the following procedure. “Toyo Kasei Co., Ltd.“ YP-50 ”(epoxy equivalent 87600 g / eq based on JIS K7236, weight average molecular weight 60000-80000 by GPC, glass transition point 84 ° C. by DSC method (10 ° C./min increase)) / Dissolved in cyclohexanone to obtain a primer layer varnish. The solid content in the varnish is 27% by mass.

“Phenoxy 3” in the table means a copolymer-modified phenoxy resin of bisphenol A type and bisphenol F type, and a varnish was obtained by the following procedure. “ZX-1356-2” (GPC weight average molecular weight 60000-80000, glass transition point 72 ° C. by DSC method (10 ° C./min increase)) of Toto Kasei Co., Ltd. was dissolved in cresol / cyclohexanone to give bisphenol A A varnish for a primer layer was prepared by mixing 20 parts by mass of MS50 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as a blocked isocyanate with 100 parts by mass of a copolymer-modified phenoxy resin of a type and a bisphenol F type. The solid content in the varnish is 27% by mass. The elastic modulus of the resin obtained by baking the resin varnish in the coating step was 1.7 GPa at 50 ° C. and 0.015 GPa at 200 ° C.

“High strength AI” in the table means biphenyl-containing polyamideimide, and varnish was obtained by the following procedure. First, trimellitic anhydride (TMA) 108 was flowed through a flask equipped with a thermometer, a cooling device, 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. , 6 g, 3,3′-dimethylbiphenyl-4,4′-diisocyanate (TODI) 29.9 g, and diphenylmethane-4,4′-diisocyanate (MDI) 113.1 g. The proportion of TODI in all diisocyanates was 20 mol%. Next, 637 g of N-methyl-2-pyrrolidone was placed in the flask, heated at 80 ° C. for 3 hours while stirring with a stirrer, and further heated to 140 ° C. over 3 hours. Heated at 0 ° C. for 1 hour. Then, when 1 hour had passed, heating was stopped and the mixture was allowed to cool to obtain a varnish for a biphenyl-containing polyamideimide layer having a concentration of 25% by mass.

“General-purpose PI” in the table means general-purpose polyimide, and varnish was obtained by the following procedure. First, 4,4'-diaminodiphenyl ether (ODA) was dissolved in N-methylpyrrolidone, pyromellitic dianhydride (PMDA) was added, and the mixture was stirred at room temperature for 1 hour in a nitrogen atmosphere. Thereafter, the mixture was stirred at 60 ° C. for 20 hours to finish the reaction, and cooled to room temperature to obtain a polyimide resin varnish. The blending ratio (molar ratio) of ODA and PMDA was 100: 100.

“Flexible AI” in the table refers to Voltatex 9100 (manufactured by DuPont). The elastic modulus of the resin obtained by baking this resin varnish in the coating step was 2.2 GPa at 50 ° C. and 0.025 GPa at 200 ° C.

[Reference example]
A copper conductor was obtained by using copper instead of aluminum. A general wire drawing lubricant was used as the lubricant during wire drawing. The peripheral carbon concentration of this conductor was as shown in Table 3. An insulating layer having the configuration shown in Table 3 was laminated on the peripheral surface of the conductor to obtain an insulated wire of a reference example.

For each of the insulated wires obtained in Examples 1 to 32, Comparative Examples 1 to 9, and Reference Example, the number of twists until the insulation layer was peeled, the dielectric breakdown voltage, and the scratching load were measured. The measurement results are shown in Table 1, Table 2, and Table 3.

As shown in the results of Table 1, Table 2 and Table 3, the insulated wires of Examples 1 to 32 have high scratching load, high scratch resistance, and the insulated wires of Reference Example using copper conductors. Equivalent or better performance. In addition, since the dielectric breakdown voltage is high, the insulation characteristics are also excellent. In addition, although the comparative example 2 seems to be inferior in the twist frequency and the dielectric breakdown voltage compared with the comparative example 1 which has not performed the carbon concentration reduction process (cleaning process with water), the comparative example 1 and the comparative example 2 The difference between these values is considered to be within the measurement error.

As described above, the insulated wire of the present invention has high adhesion, scratch resistance, and insulating properties while using aluminum or an aluminum alloy as a conductor. Therefore, the said insulated wire can be used suitably for a motor, an alternator, an ignition etc., for example.

Claims (10)

1. An insulated wire comprising a conductor mainly composed of aluminum or an aluminum alloy and an insulating layer covering the peripheral surface of the conductor,
   An insulated wire characterized in that the average number of twists until peeling of the insulating layer in the peel test is 50 or more.
2. The insulated wire according to claim 1, wherein an average value of a dielectric breakdown voltage per unit thickness of the insulating layer in the glycerin solution is 0.15 kV / µm or more.
3. The insulated wire according to claim 1 or 2, wherein a carbon concentration of the conductor peripheral surface is 10% by mass or less.
4. The insulated wire according to claim 1, wherein the conductor peripheral surface is subjected to carbon reduction treatment.
5. The insulated wire according to claim 4, wherein the carbon reduction treatment is a washing treatment using a liquid.
6. The insulating layer is
   A primer layer that is laminated on the peripheral surface of the conductor and contains a phenoxy resin as a main component;
   A biphenyl-containing polyamideimide layer containing a biphenyl-containing polyamideimide resin as a main component,
   The insulated wire according to any one of claims 1 to 5, wherein an average thickness of the primer layer is 0.5 µm or more and 5 µm or less.
7. The insulated wire according to claim 6, wherein the isocyanate component forming the biphenyl-containing polyamideimide resin contains a biphenyl-containing diisocyanate compound as an amideimide raw material.
8. The insulating layer further has another resin layer,
   The insulated wire according to claim 6 or 7, wherein the other resin layer contains a polyesterimide resin, a polyamideimide resin, or a polyimide resin as a main component.
9. The insulated wire according to any one of claims 1 to 8, further comprising a surface lubricating layer mainly composed of a polyamide-imide resin containing a lubricant on a peripheral surface of the insulating layer.
10. A method for producing an insulated wire comprising a conductor mainly composed of aluminum or an aluminum alloy and an insulating layer covering a peripheral surface of the conductor,
    Obtaining the conductor,
    A method for producing an insulated wire, comprising: performing a carbon reduction process on the conductor peripheral surface; and coating an insulating layer on the peripheral surface of the conductor.