JP3717297B2 - Insulated wire - Google Patents

Description

【００３３】
【表２】

【００３４】
各実施例の絶縁電線の耐傷性の向上はＪＩＳ Ｃ ３００３に規定されている一方向摩耗試験で確認された。この試験は荷重を漸次増加させながら皮膜をピアノ線で削る試験であるが、実施例の絶縁電線は高荷重（２０００〜３０００ｇ）域で絶縁皮膜の中間層および上層のみ削りとられ、下層が残留している現象が見られた。この現象は比較例ではみられなかった新規で特異な現象であった。
この現象をさらに説明すると、各実施例の、本発明の絶縁電線では、漸次増加する荷重によって皮膜に相当の力が加わっても異種の皮膜が積層していることでこの力を逃がすうえ、最下層と導体が強く密着しているため、加わった力で絶縁皮膜を最下層まで全てけずりとられてしまうことがなく、傷は導体まで達しなかったものと考えられる。
【００３５】
これに対し、比較例１、２の電線の場合、本発明における中間層にあたるポリイミド樹脂層がないため、高荷重がかかった場合にかかる力を分散させることができず、一気に導体まで傷が進行してしまい、目的とする耐傷性特性が得られなかった。
比較例３、４の電線の場合には、実施例１で用いた塗料と同じトリメチルアミン及びメトキシ化メラミン樹脂を配合したポリアミドイミド塗料を用いているが、絶縁皮膜が多層でないため、かかる力を分散させることができず、やはり一気に導体まで傷が進行してしまい、目的とする耐傷性特性が得られなかった。
比較例５、６の電線の場合は、中間層のポリイミド樹脂層によってかかる力は分散されるものの、絶縁皮膜の導体への密着力が実施例のものと比べて低いため、十分な耐傷性が得られなかった。
比較例７の電線の絶縁皮膜は中間層のない２層構造としたが、実施例１のものと比較して、やはり耐傷性が十分でなかった。
比較例８の電線の絶縁皮膜は実施例と同様の３層構造としたが、下層用塗料中のトリアルキルアミン、アルコキシ化メラミン樹脂の配合量が少ないため十分な耐傷性特性は得られなかった。
すなわち本発明の絶縁電線は、導体に強く密着した下層、加わった応力を緩和する中間層、及び摩擦係数の低い上層を有する多層構造の絶縁皮膜を有することにより、従来にない耐傷性を発現していることがわかる。
【００３６】
【発明の効果】
本発明の絶縁電線は高い耐傷性を有し、過酷なコイル加工の条件下で高い負荷がかかっても傷が導体まで達しにくく、絶縁不良を起こしにくい。また、本発明の絶縁電線においては、絶縁皮膜を薄肉化しても高い耐傷性が維持されるため、絶縁電線の占積率を低減させて、信頼性の高いコイルが提供でき、コイルを用いる機器全体の小型化、低コスト化、信頼性向上に寄与するという優れた効果を奏する。
【図面の簡単な説明】
【図１】本発明の絶縁電線の一実施態様を示す断面図である。
【図２】ピアノ線による皮膜損傷荷重測定方法の試験装置の模式図である。
【図３】静摩擦係数測定装置の平面図である。
【図４】静摩擦係数測定装置の側面図である。
【符号の説明】
１ 導体
２ 絶縁皮膜の下層
３ 絶縁皮膜の中間層
４ 絶縁皮膜の上層
５ 荷重
６ 絶縁電線
７ ピアノ線
１１ 絶縁電線
１２ スライダー
１３ 荷重
１４ 絶縁電線[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an insulated wire that is suitable for coils of motors, generators and the like and has excellent scratch resistance.
[0002]
[Prior art]
Insulated wires coated with an electrical insulator are used in large quantities for applications of coils incorporated in various electrical devices. In recent years, speeding up and rationalization in the coil winding process of this insulated wire have been promoted, and the coil winding operation has been shifted from conventional manual winding to processing by an automatic coil winding machine. Also, the insertion of the coil into the status lot is automated.
However, when this automatic coil winding process is performed, since a large tension is applied to the insulated wire, the stress of the film is large, and the insulated wire is apt to be damaged. In addition, when inserting a coil into a status lot, since what has been pushed in by hand has been pushed by the machine, a greater pressure has been applied to the electric wire. Under such an environment, rubbing between the electric wires or between the electric wire and the electric wire contact object is more likely to occur, and the insulation failure of the coil is liable to occur.
[0003]
In addition, increasing the space factor of the insulated wire in the status lot in the coil as much as possible results in downsizing of the entire device and cost reduction, and thus there is a demand for a reduction in the outer diameter of the wire. In recent years, with this reduction in diameter, there has been a demand for deferring or increasing the conductor diameter in order to further increase the power of equipment, and it has become necessary to reduce the thickness of the insulating film.
However, the thinning of the insulating film increases the frequency of film damage and increases the incidence of coil insulation failure in the case of automating coil winding or coil insertion into a status lot.
In order to solve the above problem, it is conceivable to reduce the friction coefficient between the electric wires or the objects (metal rod, interphase paper, etc.) in contact with the electric wires and to improve the film strength. The lower the coefficient of friction, the easier the coil winding process, and the stronger the coating strength, the less damage during coil winding and coil insertion into the status lot (hereinafter referred to as coil processing). Become.
[0004]
Conventional means for reducing the friction coefficient include a method of applying a lubricant to the surface of an electric wire, or a method of applying and baking a lubricant in an insulating paint.
As a technique for improving the film strength, an insulated wire coated with a polyamide-imide paint and baked is usually used. This wire has high mechanical strength and excellent wear resistance compared to other resins (polyester, polyurethane, polyesterimide, polyesteramideimide, polyimide), so it is often used when the coil processing conditions are severe. It was.
[0005]
However, in recent years, the conditions for coil processing have become more severe, and even if the coefficient of friction is reduced as described above, or even if a wire coated with a polyamide-imide resin paint is baked, damage to the film cannot be prevented. Has increased.
Thus, as one means for preventing film damage during coil processing, a method for improving the adhesion between the insulating layer and the conductor has been proposed. As specific examples of the insulating paint for that purpose, 1) a heat-resistant paint comprising a polyamidoimide resin, an alkoxy-modified amino resin, and benzotriazole (JP-A-3-37283), 2) a paint comprising a polyamidoimide resin and a trialkylamine ( Japanese Patent Laid-Open No. 6-116632) has been proposed.
An electric wire using these methods is effective in a reciprocating wear test (a test in which a relatively low load is applied to the electric wire and the coating is rubbed with a bead needle). However, no effect is observed in the unidirectional wear test (the test prescribed in JIS C 3003; a test in which a film is scratched with a piano wire while gradually applying a load to an electric wire). In recent years, the latter test method has been regarded as important as a film damage test.
In addition, electric wires that use only the adhesion improvement technique have a reciprocating wear value that decreases as the film thickness decreases, and can be almost the same level as conventional cables that do not use the adhesion improvement technique. There were many.
[0006]
On the other hand, from the viewpoint of the molecular structure of the resin, there has also been proposed a method of introducing a lot of rigid structures in the molecule to improve the film strength and reduce the processing flaws of the film. An insulated wire having an insulating film that defines strength and tensile modulus is described. Such an electric wire has a remarkable effect in the unidirectional wear test, and even if the wire is thinned, it is possible to prevent damage to the film during coil processing. However, such an insulated wire has a lower level of flexibility after being stretched and subjected to a thermal history than conventional wires, and is particularly flexible when subjected to severe bending. Is not sufficient, there was a risk of cracking and cracking in the film.
[0007]
Moreover, as an example in which a plurality of different types of coatings are laminated to improve the mechanical strength and thermal shock resistance of the coating, there is a technique described in Japanese Patent Publication No. 62-21203. In this example, an insulated wire is disclosed in which a polyamideimide resin is provided in the lowermost layer, an aromatic polyimide resin is provided in the intermediate layer, and a polyamideimide resin is provided in the upper layer to improve the mechanical properties of the film and the thermal shock resistance after varnish impregnation treatment. ing. In this wire, the reciprocal wear value is improved, and when subjected to heat treatment after varnish impregnation treatment, the varnish pulls the film, and this force is relaxed in the intermediate layer, preventing the film from cracking and cracking. The However, although the reciprocating wear value is improved, it is not effective for unidirectional wear, and the reciprocating wear value also decreases when the wall thickness is reduced. Therefore, further improvements can be made to prevent damage to the film during coil processing. It was necessary.
[0008]
[Problems to be solved by the invention]
The objective of this invention is providing the insulated wire which can prevent the membrane | film | coat damage at the time of coil processing on severe conditions, even if an insulation membrane is thin.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present inventors sufficiently observed the state of film damage when thinning the insulation film of the conventional insulated wire with a microscope or the like, and analyzed the mechanism of each damage, In order to solve the above problems, the conductor and the insulating film are brought into close contact with each other, the friction coefficient of the electric wire surface is reduced, and the load applied to the electric wire is dispersed in the insulating film. I found it necessary. Furthermore, it discovered that said 3 points | pieces were realizable simultaneously by making an insulating film into a specific multilayer structure, and came to complete this invention based on this knowledge.
That is, the present invention
(1) Polyamideimide system comprising 0.05 to 1.0 parts by weight of trialkylamine and / or 5 to 20 parts by weight of alkoxylated melamine resin with respect to 100 parts by weight of polyamideimide resin on the conductor. An insulating film comprising at least three layers: a lower layer formed by applying and baking a resin paint, an intermediate layer formed by applying and baking a polyimide resin paint, and an upper layer formed by applying and baking a self-lubricating polyamideimide resin paint An insulated wire characterized by having,
(2) The thickness of the polyimide resin is 10 to 40% of the total insulation film thickness, and (3) the insulation film has a thickness of 20 to 30 μm. The insulated wire according to item (1) or (2) is provided.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below.
The base resin of the polyamide-imide resin paint used for forming the lower layer of the insulating film in the present invention is not particularly limited, and a tricarboxylic acid anhydride and a diisocyanate are directly reacted in a conventional method, for example, in a polar solvent. A product obtained or a product obtained by first reacting a diamine with a tricarboxylic acid anhydride in a polar solvent, first introducing an imide bond, and then amidating with a diisocyanate can be used.
[0011]
As the tricarboxylic acid anhydride used for preparing the resin, trimellitic acid anhydride is usually used. In this case, a part of the tricarboxylic acid anhydride may be replaced with a tetracarboxylic acid anhydride for the reaction. Examples of the tetracarboxylic acid anhydride used here include pyromellitic dianhydride and 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride. In addition, a part of the tricarboxylic acid anhydride may be replaced with another acid or acid anhydride such as trimellitic acid, isophthalic acid, terephthalic acid, or the like. On the other hand, examples of the diisocyanates to be reacted with the tricarboxylic acid anhydride include aromatic diisocyanates such as 4,4′-diphenylmethane diisocyanate and tolylene diisocyanate, and examples of the diamine include m-phenylenediamine and 4,4 ′. -Aromatic diamines such as diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylsulfone, and 4,4′-diaminobenzophenone. Further, N, N′-dimethylformamide may be used for imidization. As the polar solvent, N-methyl-2-pyrrolidone can be preferably used.
[0012]
By blending the trialkylamine and / or alkoxylated melamine resin into the base resin solution thus obtained, a polyamideimide resin coating used for the lower layer of the insulating film can be obtained.
The trialkylamine is preferably a lower alkyl trialkylamine such as trimethylamine, triethylamine, tripropylamine or tributylamine. Among these, trimethylamine and triethylamine are most preferable in terms of flexibility and adhesion. The compounding ratio with respect to the polyamide-imide resin is usually 0.05 to 1.0 part by weight, preferably 0.1 to 1 part by weight with respect to 100 parts by weight of the polyamide-imide resin. If the trialkylamine is added in an amount exceeding 1.0 part by weight, the heat resistance of the film is lowered, and if it is less than 0.05 part by weight, it does not contribute to adhesion.
In addition, as the alkoxylated melamine resin used in the present invention, for example, a melamine resin substituted with a lower alkoxy group such as butoxylated melamine resin or methoxylated melamine resin can be used. Melamine resins are preferred. The blending ratio is usually 5 to 20 parts by weight, preferably 10 to 20 parts by weight, based on 100 parts by weight of the polyamideimide resin. When the amount is less than 5 parts by weight, sufficient adhesion cannot be obtained, and when the amount exceeds 20 parts by weight, the heat resistance of the film decreases.
The polyamideimide-based resin paint thus obtained is applied to a conductor and baked to form a lower layer of an insulating film on the conductor.
[0013]
In the present invention, the polyimide resin used for the intermediate layer of the insulating film is a polyamic acid solution obtained by reacting an aromatic tetracarboxylic dianhydride and an aromatic diamine in a polar solvent. It is obtained by imidization by heat treatment. There is no restriction | limiting in particular in aromatic tetracarboxylic acid anhydride, What is used normally can be used, for example, pyromellitic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 3 , 3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, and derivatives thereof. In terms of easy availability, pyromellitic dianhydride is most preferable. The aromatic diamines are not particularly limited, and examples thereof include 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl sulfone, 4,4′-diaminobenzophenone, 4,4′-diaminodiphenylmethane, and the like. 4,4′-diaminodiphenyl ether is preferred because it is easily available.
Such a polyamic acid solution is applied onto the lower film and baked to form an intermediate layer made of a polyimide resin film.
In the present invention, this intermediate layer acts so that stress is not directly transmitted to the lower layer of the insulating film when a large load is applied to the insulated wire.
[0014]
In the present invention, the base resin of the polyamide-imide resin paint that forms the upper layer of the insulating film can be prepared in the same manner as the base resin of the polyamide-imide resin paint for forming the lowermost layer. In this manner, wax or a lubricant is dispersed and mixed by a conventional method to form a self-lubricating polyamideimide resin coating for the upper layer. As the wax to be dispersed and mixed, those usually used can be used without particular limitation. For example, synthetic waxes such as polyethylene wax, petroleum wax, paraffin wax, and natural waxes such as carnauba wax, cadilla wax, and rice wax. A wax etc. are mentioned. There is no restriction | limiting in particular also about a lubricant, For example, silicone, a silicone macromonomer, a fluororesin etc. can be used.
Such a self-lubricating polyamideimide resin coating is further applied and baked on the intermediate layer to provide an upper layer made of self-lubricating polyamideimide.
In addition, in the insulated wire of this invention, there is no restriction | limiting in particular in the application | coating and baking conditions of the resin coating material for forming each layer of an insulating film, It can carry out by various well-known methods. Moreover, there is no restriction | limiting in particular also about a conductor.
[0015]
The insulated wire of the present invention has an insulating film having a multilayer structure as described above,
1) Dispersing the stress applied from the outside between the layers of the insulating film,
2) To strengthen the adhesion between the conductor and the lower layer of the insulating film that is in direct contact with the conductor;
3) A reduction in the friction coefficient of the surface of the insulated wire has been realized at the same time, and for the first time, even if the insulation film thickness is reduced to 30 μm or less, it has scratch resistance that can withstand coil processing under severe conditions. It can have. From the viewpoint of both scratch resistance and thinning, it is preferable that the insulation film thickness of the insulated wire of the present invention is 20 to 30 μm in total film thickness.
In this invention, it is preferable that the ratio of the film thickness of an intermediate | middle layer is 10 to 40% with respect to the total insulation film thickness. By setting the intermediate layer to this thickness, the scratch resistance of the insulating film is effectively improved. There is no restriction | limiting in particular about the film thickness of a lower layer and an upper layer.
[0016]
【Example】
Hereinafter, the present invention will be described in more detail based on examples.
In addition, the composition (weight part) of the lower layer of the insulation film of the insulated wire of an Example and a comparative example was put together in Table 1 and Table 2, and was shown.
Example 1
Attach stirrer, condenser and calcium chloride tube to a 2 liter four-necked flask and charge 192 g of trimellitic anhydride, 250 g of 4,4′-diphenylmethane diisocyanate and 663 g of N-methyl-2-pyrrolidone at 80 ° C. The temperature was raised for 2 hours and reacted at 140 ° C. for 5 hours. Thereafter, the mixture was cooled to 50 ° C., and 163 g of N, N′-dimethylformamide was added for dilution. Further, 1.8 g of trimethylamine was added, 35.4 g of a methoxylated melamine resin (trade name: Cymel 300, manufactured by Mitsui Cyanamid Co., Ltd.) was added, and the mixture was stirred for 1 hour to obtain a polyamideimide resin coating for the lower layer of the insulating film. .
[0017]
A three-liter four-necked flask was equipped with a stirrer, a condenser tube, and a calcium chloride tube, charged with 218 g of pyromellitic anhydride, 200 g of 4,4′-diaminodiphenyl ether, and 1672 g of N-methyl-2-pyrrolidone, and the temperature was 30. The reaction was allowed to proceed for 5 hours while keeping the temperature below ℃ or below to obtain a polyimide resin coating for the intermediate layer.
A commercially available polyamideimide resin coating (trade name: HI406, manufactured by Hitachi Chemical Co., Ltd.) and polyethylene wax (trade name; Sunwax 131P, manufactured by Sanyo Chemical Industries Co., Ltd.) are blended in an amount of 1% by weight based on the resin solid content. A self-lubricating polyamide-imide resin coating for the upper layer was obtained.
The above-mentioned lower layer coating material was applied and baked a plurality of times on a 1.0 mmφ copper wire using a baking furnace having a furnace length of 8 m to form a lower layer of an insulating film having a thickness of 19 μm. On this, the intermediate layer coating material was applied and baked once to form an intermediate layer having a thickness of 3 μm. Further, the above-mentioned upper layer coating material was applied and baked once thereon to form an upper layer having a thickness of 3 μm, and an insulated wire having a total insulating film thickness of 25 μm was obtained.
FIG. 1 shows a cross-sectional view of one embodiment of the insulated wire of the present invention prepared as described above. In FIG. 1, reference numeral 1 denotes a conductor (copper wire), and the lower layer 2 of the insulating film, the intermediate layer 3 of the insulating film, and the upper layer 4 of the insulating film are respectively formed on the conductor using the above-mentioned paints. It is formed with the film thickness.
[0018]
Example 2
The lower layer film thickness 19 μm, the intermediate layer film thickness 3 μm, the upper layer film thickness 3 μm, and the total insulation film film thickness 25 μm, except that the amount of trimethylamine in the coating for the lower layer of the insulating film was 3.6 g. An insulated wire was obtained.
[0019]
Example 3
In the same manner as in Example 1 except that 3.6 g of triethylamine was added instead of trimethylamine in the coating for the lower layer of the insulating film, and 35.4 g of butoxylated melamine resin was added instead of methylated melamine resin, the lower layer film thickness was 19 μm, An insulated wire having an intermediate layer thickness of 3 μm, an upper layer thickness of 3 μm, and a total insulating film thickness of 25 μm was obtained.
[0020]
Example 4
In the same manner as in Example 3, except that the blending amount of triethylamine in the coating for the lower layer of the insulating film was 1.8 g and the blending amount of the butoxylated melamine resin was 35.4 g, the lower layer film thickness was 19 μm and the intermediate layer film thickness was 3 μm. An insulated wire having an upper layer thickness of 3 μm and a total insulating film thickness of 25 μm was obtained.
[0021]
Example 5
An insulated wire having a total insulating film thickness of 25 μm was obtained in the same manner as in Example 1 except that the film thickness of the insulating film was 16 μm for the lower layer and 6 μm for the intermediate layer.
[0022]
Example 6
An insulated wire having a total insulating film thickness of 20 μm was obtained in the same manner as in Example 1 except that the insulating film thickness was 14 μm.
Example 7
An insulated wire having a total insulating film thickness of 20 μm was obtained in the same manner as in Example 3 except that the thickness of the insulating film was 14 μm.
[0023]
Example 8
Insulated wire having a lower layer thickness of 19 μm, an intermediate layer thickness of 3 μm, an upper layer thickness of 3 μm, and a total insulating coating thickness of 25 μm, except that the methoxylated melamine resin was removed from the lower layer coating of the insulating coating. Got.
Example 9
An insulated wire having a lower layer thickness of 19 μm, an intermediate layer thickness of 3 μm, an upper layer thickness of 3 μm, and a total insulating coating thickness of 25 μm was obtained in the same manner as in Example 1 except that trimethylamine was removed from the lower coating for the insulating coating. .
[0024]
Example 10
A two-liter four-necked flask is equipped with a stirrer, a condenser tube, and a calcium chloride tube, 192 g (1.0 mol) of trimellitic anhydride, 99 g (0.5 mol) of 4,4′-diaminodiphenylmethane, N-methyl-2 -The pyrrolidone 436.5g was prepared, and it heated up to the content temperature of 200 degreeC, and was made to react for 2 hours. Water generated during the reaction was appropriately removed from the system. Thereafter, the temperature was once lowered to 80 ° C., 125 g (0.5 mol) of 4,4′-diphenylmethane diisocyanate was added, and the temperature was raised to 140 ° C. and reacted for 5 hours. Thereafter, the mixture was cooled to 50 ° C., and 140 g of N-methyl-2-pyrrolidone was added to obtain a polyamideimide resin paint having a nonvolatile content of 30%. Trimethylamine 1.24 g and methoxylated melamine resin 24.7 g were added to this resin paint to obtain a polyamideimide resin paint for the lower layer of the insulating film.
The above-mentioned coating material was applied and baked a plurality of times on a 1.0 mmφ copper wire using a baking oven having a furnace length of 8 m to form a lower layer of an insulating film having a thickness of 19 μm. On top of this, the polyimide resin paint described in Example 1 was applied and baked once to form an intermediate layer having a thickness of 3 μm. Furthermore, the upper layer self-lubricating polyamideimide resin coating material described in Example 1 was applied and baked once thereon to form an upper layer having a thickness of 3 μm, and an insulated wire having a total insulating film thickness of 25 μm was obtained. .
[0025]
Comparative Example 1
A commercially available polyamide-imide resin paint (trade name: HI406, manufactured by Hitachi Chemical Co., Ltd.) was applied and baked several times on a 1.0 mmφ copper wire using a vertical baking furnace with a furnace length of 8 m, and the film thickness of the insulating film was 35 μm. An insulated wire was obtained.
Comparative Example 2
An insulated wire was obtained in the same manner as in Comparative Example 1 except that the thickness of the insulating film was 25 μm.
Comparative Example 3
The coating for the lower layer of the insulating film used in Example 1 was applied and baked a plurality of times on a 1.0 mmφ copper wire using a vertical baking furnace having a furnace length of 8 m to obtain an insulated wire having an insulating film thickness of 35 μm.
[0026]
Comparative Example 4
An insulated wire was obtained in the same manner as in Comparative Example 3 except that the thickness of the insulating film was 25 μm.
[0027]
Comparative Example 5
The commercially available polyamideimide resin paint used in Comparative Example 1 was applied and baked several times on a 1.0 mmφ copper wire using a vertical baking furnace having a furnace length of 8 m to form a lower layer having a thickness of 20 μm. On this, the intermediate layer coating material used in Example 1 was applied and baked a plurality of times to form an intermediate layer having a thickness of 10 μm. Further, the above-mentioned commercially available polyamideimide resin paint was applied and baked thereon to form an upper layer having a thickness of 5 μm, and an insulated wire having a total insulation film thickness of 35 μm was obtained.
Comparative Example 6
An insulated wire having a total insulating film thickness of 25 μm was obtained in the same manner as in Comparative Example 5 except that the film thickness of the lower layer of the insulating film was 10 μm.
[0028]
Comparative Example 7
The coating for the lower layer of the insulating film used in Example 1 was applied and baked several times on a 1.0 mmφ copper wire using a vertical baking furnace having a furnace length of 8 m to form a lower layer having a thickness of 22 μm. On this, the upper layer coating material used in Example 1 was applied and baked once to form an upper layer having a thickness of 3 μm, thereby obtaining an insulated wire having a total thickness of 25 μm.
Comparative Example 8
In the same manner as in Example 1 except that the blending amount of trimethylamine in the coating for the lower layer of the insulating film was 0.11 g and the blending amount of the methoxylated melamine resin was 10.6 g, the lower layer film thickness was 19 μm, the intermediate layer film thickness was 3 μm, An insulated wire having an upper layer thickness of 3 μm and a total insulating film thickness of 25 μm was obtained.
[0029]
The scratch resistance evaluation of various insulated wires obtained in the above Examples and Comparative Examples was evaluated by the following test methods.
(1) Unidirectional wear test It was performed according to JIS C 3003.
(2) Reciprocal wear test The test was performed according to the former JIS C 3003 (1974).
(3) Measurement of film damage load by piano wire As shown in the schematic diagram of FIG. 2, the insulated wire 6 and the piano wire 7 are orthogonally crossed, a constant load 5 is applied to the piano wire, and the insulated wire is pulled to remove the film. And the load at which the conductor was exposed was measured.
(4) Coil leakage current measurement status Insert a coil into the status lot using an inserter winding machine, then immerse it in a 5% strength by weight saline solution with a counter electrode, and apply a DC voltage of 12V with the coil as the positive electrode. Then, the leaked current value was measured.
[0030]
(5) Copper wire and film adhesion test (conforming to JIS C 3003)
After the test piece was subjected to a tensile tester, the cut portion was observed with a microscope, and the length of the film floating from the conductor was measured.
(6) Coefficient of static friction Measured with an apparatus having a plan view in FIG. 3 and a side view in FIG. That is, the coefficient of static friction between the insulated wire 11 wound around the slider 12 and the insulated wire 14 fixed on the table was calculated from the load 13 applied to the slider.
(7) The flexible insulated wire after 20% elongation was stretched by 20%, and then wound around a mandrel having a diameter corresponding to the conductor diameter of the wire, and the presence or absence of cracks was observed.
[0031]
The results evaluated by the above test methods are shown in Tables 1 and 2.
[0032]
[Table 1]

[0033]
[Table 2]

[0034]
The improvement of the scratch resistance of the insulated wire in each example was confirmed by a unidirectional wear test specified in JIS C 3003. This test is a test in which the film is shaved with a piano wire while gradually increasing the load, but the insulated wire of the example is scraped only in the intermediate layer and the upper layer of the insulating film in the high load (2000 to 3000 g) region, and the lower layer remains. This phenomenon was observed. This phenomenon was a novel and unique phenomenon that was not seen in the comparative example.
To further explain this phenomenon, in the insulated wire of the present invention of each example, even when a considerable force is applied to the film due to a gradually increasing load, the different types of films are laminated, and this force is released. Since the lower layer and the conductor are in close contact with each other, the applied film does not scrape all the insulating film down to the lowermost layer, and it is considered that the scratch did not reach the conductor.
[0035]
On the other hand, in the case of the electric wires of Comparative Examples 1 and 2, since there is no polyimide resin layer corresponding to the intermediate layer in the present invention, the force applied when a high load is applied cannot be dispersed, and scratches progress to the conductor at once. As a result, the intended scratch resistance characteristic could not be obtained.
In the case of the wires of Comparative Examples 3 and 4, the same polyamide imide paint as the paint used in Example 1 and a polyamidoimide paint blended with a methoxylated melamine resin are used. As a result, scratches progressed to the conductor all at once, and the intended scratch resistance characteristics could not be obtained.
In the case of the electric wires of Comparative Examples 5 and 6, although the force applied by the polyimide resin layer of the intermediate layer is dispersed, the adhesion strength of the insulating film to the conductor is lower than that of the example, so that the scratch resistance is sufficient. It was not obtained.
Although the insulating film of the electric wire of Comparative Example 7 had a two-layer structure without an intermediate layer, it was still insufficient in scratch resistance as compared with that of Example 1.
The insulation film of the electric wire of Comparative Example 8 had a three-layer structure similar to that of the example, but sufficient scratch resistance characteristics could not be obtained due to the small amount of trialkylamine and alkoxylated melamine resin in the lower layer coating. .
That is, the insulated wire of the present invention has a multi-layered insulating film having a lower layer that is strongly adhered to the conductor, an intermediate layer that relieves applied stress, and an upper layer that has a low coefficient of friction, and thus exhibits unprecedented scratch resistance. You can see that
[0036]
【The invention's effect】
The insulated electric wire of the present invention has high scratch resistance, and even when a high load is applied under severe coil processing conditions, the scratch does not easily reach the conductor and hardly causes poor insulation. In addition, in the insulated wire of the present invention, high scratch resistance is maintained even if the insulation film is thinned. Therefore, the space factor of the insulated wire can be reduced, and a highly reliable coil can be provided. It has an excellent effect of contributing to overall downsizing, cost reduction, and reliability improvement.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of an insulated wire according to the present invention.
FIG. 2 is a schematic diagram of a test apparatus for a method for measuring a film damage load with a piano wire.
FIG. 3 is a plan view of a static friction coefficient measuring apparatus.
FIG. 4 is a side view of the static friction coefficient measuring apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Conductor 2 Lower layer of insulating film 3 Intermediate layer of insulating film 4 Upper layer of insulating film 5 Load 6 Insulated wire 7 Piano wire 11 Insulated wire 12 Slider 13 Load 14 Insulated wire

Claims (3)

A polyamide-imide resin coating comprising 0.05 to 1.0 parts by weight of trialkylamine and / or 5 to 20 parts by weight of alkoxylated melamine resin with respect to 100 parts by weight of polyamide-imide resin on a conductor. It has an insulating film consisting of at least three layers of a lower layer formed by coating and baking, an intermediate layer formed by coating and baking a polyimide resin coating, and an upper layer formed by coating and baking a self-lubricating polyamideimide resin coating. Characterized insulated wire. The insulated wire according to claim 1, wherein the thickness of the polyimide resin is 10 to 40% of the total thickness of the insulating film. The insulated wire according to claim 1 or 2, wherein the insulating film has a thickness of 20 to 30 µm.

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