JP3911274B2 - Enamel wire and insulating coating used therefor - Google Patents

Description

  The present invention relates to an enameled wire used for an electric device such as a motor or a transformer and an insulating paint used therefor.

  Generally, an enameled wire is provided with an insulating film made of an insulating paint around a conductor. When using this enameled wire to make an electrical device such as a motor or a transformer, it is generally formed by winding the enameled wire continuously in a coil shape around the motor core (magnetic core) slot, Alternatively, a method in which an enameled wire wound in a coil shape is fitted and inserted into a slot of the core has been the mainstream.

  On the other hand, in the case of enameled wire with a large cross-sectional area (thick size) or enameled wire with a flat rectangular conductor, the enameled wire is not continuously wound to form a long coil with a large number of turns. A method has been proposed in which a plurality of small short-diameter coils are formed, and the enameled wire ends of these small-diameter coils are welded together to form a long coil. The coil formed in this way is used for a coil of an electric device that is small and requires a high-density magnetic flux, for example, a coil of an automobile generator or the like.

  For coils such as automobile generators, double-coated wires in which a polyesterimide insulation film is formed around a conductor and a polyamideimide insulation film is provided around the polyesterimide insulation film, or a polyamideimide around a conductor Single-coated wires with an insulating film are mainly used. In some cases, double-coated wires with a polyimide insulating film formed around the conductor and a polyamide-imide insulating film around the polyimide insulating film to improve heat resistance and mechanical strength are also used. (For example, refer to Patent Document 1).

Japanese Patent Laid-Open No. 5-130759

  By the way, in a coil of an automobile generator or the like, when welding the enameled wire terminal of each of the short coils described above, it is a mainstream to use an electric welding method such as TIG welding or fusing.

  When performing TIG welding or fusing, the weld of each coil is heated to 1084 ° C. or higher, which is the melting point of copper, in order to dissolve copper. Since this heat is also transmitted to the insulating film in the vicinity of the welded portion, the insulating film is also rapidly heated.

  At this time, in the conventional double-coated wire made of the polyesterimide and polyamideimide insulating film and the single-coated wire made of the polyamideimide film, the insulating film is thermally decomposed and gas is generated due to the high temperature caused by welding. The moisture absorbed in the insulating film and the solvent component remaining (residual) in the film after the baking of the insulating film are rapidly vaporized. As a result, the insulating film is pushed up from the surface of the conductor by these pyrolysis gas and vaporized gas, and is peeled off from the conductor and floats (hereinafter referred to as film floating), or foaming called a blister occurs. Therefore, there is a problem that the reliability of the electrical equipment is lowered.

  On the other hand, a double-coated wire composed of a polyimide resin film and a polyamideimide resin film, which have higher heat resistance than those of the polyesterimide resin and polyamideimide resin, is expensive and therefore becomes an expensive enameled wire. There was a problem. Moreover, since the adhesion between the conductor and the insulating film is poor, there is a problem that the film is liable to float.

  An object of the present invention created in view of the above circumstances is to provide a highly reliable and inexpensive enameled wire near the welded part at the time of terminal welding and an insulating coating used therefor.

In order to achieve the above object, the enameled wire according to the present invention has an insulating film composed of at least two insulating layers around a conductor, and the outermost insulating layer is composed of a polyamideimide film . In an enameled wire used for an electric device coil formed by heating the terminal of the coil to a melting point of copper or higher by using an electrical welding method , polyimide resin and polyamide are provided on the inner layer side of the outermost insulating layer. It is composed of a mixed resin film of imide resin, and is provided with a mixed resin insulating layer having a linear expansion coefficient at 300 to 400 ° C. of 5 × 10 ⁻⁴ / ° C. or less .

Here, it is preferable that the mixed resin insulating layer 1 00 parts by weight of the polyimide resin obtained by mixing 20 to 100 parts by weight of the polyamideimide resin of the mixed resin. Moreover , it is preferable that the ratio of the layer thickness of the mixed resin insulating layer to the layer thickness of the entire insulating film is 0.05 or more.

On the other hand, the insulating paint used for the enameled wire according to the present invention has an insulating film composed of at least two insulating layers around the conductor, and the outermost insulating layer is composed of a polyamideimide film, In an insulating paint used for an enameled wire used for an electric device coil formed by heating the terminal of the coil to a melting point of copper or higher by using an electric welding method , the above-mentioned inner layer side of the outermost insulating layer A mixed resin in which a polyimide resin and a polyamideimide resin are mixed at a predetermined ratio and a linear expansion coefficient at 300 to 400 ° C. is 5 × 10 ⁻⁴ / ° C. or less is used for the insulating layer .

The mixed resin is obtained by mixing 20 to 100 parts by weight of polyamideimide resin with 100 parts by weight of polyimide resin.

  According to the present invention, when an end of an enameled wire is welded, an excellent effect is exhibited that the heat resistance and weldability of the insulating film in the vicinity of the welded portion are good.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a preferred embodiment of the invention will be described with reference to the accompanying drawings.

  When the present inventors welded the end of an enameled wire, as a result of earnest research to suppress film floating and blister generation in the vicinity of the weld, the following was found.

  (1) As a material constituting the insulating film, it is necessary to use a material that has high heat resistance and is difficult to be thermally decomposed. Examples of such a material include polyimide (hereinafter referred to as PI) and polyamideimide (hereinafter referred to as PAI).

  (2) As a material constituting the insulating film, it is necessary to use a material having a small thermal deformation at a high temperature, that is, a material having a small coefficient of linear expansion. This is because when the insulating film receives rapid heat during welding, the smaller the thermal deformation, the more the film floating and blister generation can be suppressed.

  When (1) is compared between PI and PAI, PAI is more advantageous (inexpensive) in terms of cost. For this reason, the present inventors first examined an enameled wire in which an insulating film is composed of a single PAI. As a result, it was found that the enameled wire has a high coefficient of linear expansion at a high temperature of the PAI layer, so that it is not possible to suppress film floating and blister generation. Next, an enameled wire in which an insulating film was composed of PI alone was examined. As a result, this enameled wire uses PI which has better heat resistance than PAI. However, since the adhesion between the conductor and the PI layer is not sufficient, it is not possible to sufficiently suppress film floating and blistering. I understood it. Moreover, it became expensive in terms of cost.

  Therefore, as a result of further investigations by the present inventors, the insulating film as the outermost layer is not easily damaged when subjected to processing such as winding, and PAI having excellent scratch resistance is used. It was found that by using a mixed resin of PI and PAI having a small linear expansion coefficient at a part of the insulating film other than the outermost layer, it is possible to suppress film floating and blister generation.

  A cross-sectional view of an enameled wire according to a preferred embodiment of the present invention is shown in FIG.

  As shown in FIG. 1, the enameled wire 10 according to the present embodiment has an insulating film composed of insulating layers 13 and 14 of at least two layers (two layers in FIG. 1) around a conductor 11. A mixed resin insulating layer 13 composed of a mixed resin film of PI resin and PAI resin is provided on the inner layer side of the outermost insulating layer 14 composed of a PAI film. The inner layer 13 and the outer layer 14 are formed integrally (or substantially integrally).

The linear expansion coefficient of the mixed resin insulating layer 13 at 300 ° C. to 400 ° C. is 5 × 10 ⁻⁴ / ° C. or less, preferably 3.5 × 10 ⁻⁴ / ° C. or less. The reason why the linear expansion coefficient at 300 to 400 ° C is set to 5 × 10 ^-4 / ° C or less is that when the linear expansion coefficient is greater than 5 × 10 ^-4 / ° C, the insulation film floats and blisters are suppressed. This is because the effect is reduced.

  Further, the ratio between the layer thickness of the mixed resin insulating layer 13 and the layer thickness of the entire insulating film (mixed resin insulating layer 13 + outermost insulating layer 14) is not particularly specified, but is 0.05 or more, preferably 0.10 or more, More preferably, it is 0.15 or more. In this case, if the ratio of the thickness of the mixed resin insulating layer 13 to the total thickness of the insulating layer is smaller than 0.05, for example, if the layer thickness of the mixed resin insulating layer 13 is smaller than 2 μm, film floating or blistering occurs. This is because the suppressing effect is reduced.

As the insulating coating of the mixed resin of PI resin and PAI resin in the present embodiment, the linear expansion coefficient at 300 ° C. to 400 ° C. is 5 × 10 ⁻⁴ / ° C. or less and the layer thickness is about 2 μm. It is possible to produce an insulating film. The mixed resin insulating layer 13 is an insulating film formed by applying and baking this mixed resin insulating paint on the conductor 11.

  The insulating coating of PI resin referred to in the present embodiment is usually a polyamic acid solution in the state of the coating, and after applying this solution to the conductor, the polyamic acid is closed by firing in a baking furnace, and PI. It becomes a resin insulation film. As the PI resin insulating paint, a paint obtained by reacting an aromatic tetracarboxylic dianhydride and an aromatic diamine in a polar solvent is most common, and the chemical structure of PI is not particularly specified. Absent.

A typical aromatic tetracarboxylic dianhydride is:
Pyromellitic dianhydride,
Examples include benzophenone tetracarboxylic dianhydride.

Typical aromatic diamines are:
4,4′-diaminodiphenylmethane,
4,4'-diaminodiphenyl ether and the like.

  Examples of commercially available PI resin insulating paints include Pyre ML manufactured by DuPont and Trenys # 3000 manufactured by Toray.

  On the other hand, as the PAI resin insulating paint referred to in the present embodiment, a paint obtained by heating and reacting trimellitic anhydride and 4,4′-diphenylmethane diisocyanate in a polar solvent is most common. The chemical structure of PAI is not particularly specified.

  Examples of commercially available PAI resin insulation paints include HI-404 and HI-406 manufactured by Hitachi Chemical.

The mixing ratio of PI and PAI in the insulating coating of mixed resin is particularly specified if the linear expansion coefficient of mixed resin insulating layer 13 at 300 ° C. to 400 ° C. can be adjusted to 5 × 10 ⁻⁴ / ° C. or less. is not. For example, PAI (HI-406, manufactured by Hitachi Chemical Co., Ltd.) resin is mixed in a range of 20 to 100 parts by weight, preferably 30 to 100 parts by weight, with 100 parts by weight of PI (Trenice # 3000) resin. Is done. In this case, when the mixing ratio of PAI is more than 100 parts by weight, it is difficult to achieve a linear expansion coefficient of 5 × 10 ⁻⁴ / ° C. or less at 300 ° C. to 400 ° C., and the effect of suppressing film floating and blister generation This is because becomes smaller. Further, if the PAI mixing ratio is less than 20 parts by weight, the cost merit is reduced (increasing costs), which is not preferable.

  In the enameled wire 10 according to the present embodiment, it is preferable that the adhesion strength between the conductor 11 and the insulating film is stronger (higher). This is because the higher the adhesion strength between the conductor 11 and the insulating film, the greater the effect of suppressing the generation of blisters. Therefore, in order to improve the adhesion strength between the conductor 11 and the insulating film, an additive called an adhesion improver is added to the insulating coating constituting the innermost insulating layer of the insulating film provided around the conductor 11. It is preferable to do.

The adhesion improver is not particularly limited as long as it has an effect of improving the adhesion strength between the conductor 11 and the insulating film.
Melamine resins such as butylated melamine resin,
Amines such as trialkylamine,
Mercaptans such as mercaptobenzimidazole,
Polycarbodiimide resins,
Etc. Two or more types of adhesion improvers may be added in combination.

  In addition, the addition ratio of the adhesion improver to the resin content of the insulating paint can provide a sufficient effect of improving the adhesion, and does not adversely affect the characteristics of the insulating paint such as the stability of the insulating paint and the flexibility of the enameled wire 10. If it is a range, it is not specified in particular. For example, when a butylated melamine resin is used as an adhesion improver, it may be added at least 0.1 parts by weight, preferably 0.3 parts by weight or more with respect to 100 parts by weight of the mixed resin.

  In the present embodiment, a heat-resistant enameled wire 10 having a two-layer structure having an insulating film composed of a mixed resin insulating layer 13 on the inner layer side and an outermost insulating layer 14 having a PAI film on the outer layer side around the conductor 11 will be described. Although it did, the layer structure of an insulating film is not limited to two layers, Three or more layers may be sufficient. For example, as shown in FIG. 2, an enameled wire 20 having a three-layer insulating film around the conductor 11 may be used. In this case, the innermost insulating layer 22 and the outermost insulating layer 14 are composed of a PAI film, and the intermediate insulating layer 23 is composed of a mixed resin film. In the case of an enameled wire having an insulating film having a four-layer structure, the second and fourth layers from the innermost are composed of PAI films, and the first and third layers from the innermost are composed of mixed resin films. . The adhesion improver is added to the insulating paint constituting the innermost insulating layer.

  As a constituent material of the conductor 11, any material that is conventionally used as an enameled wire conductor can be applied, and although not particularly limited, Cu or a Cu alloy is preferable. Further, the cross-sectional shape of the conductor 11 is not particularly limited, and may be any one such as a circular conductor or a flat conductor. Furthermore, the cross-sectional area (size) of the conductor 11 is not particularly limited, and any conductor that is conventionally used as an enameled wire conductor can be applied.

  Next, the operation of the present embodiment will be described.

The enameled wire 10 according to the present embodiment is composed of a mixed resin film of PI resin and PAI resin on the inner layer side of the outermost insulating layer 14 composed of a PAI film, and has a linear expansion coefficient at 300 ° C. to 400 ° C. The mixed resin insulating layer 13 adjusted to 5 × 10 ⁻⁴ / ° C. or lower is provided. As a result, the insulating film has high heat resistance and is difficult to be thermally decomposed, and thermal deformation at high temperatures is reduced. As a result, when the ends of the enameled wire 10 are welded together, the insulating film is thermally decomposed due to the high temperature associated with the welding to generate gas, or even after moisture or moisture absorbed in the insulating film is baked. Even if the solvent component that remains (residual) vaporizes abruptly, it is possible to suppress film floating and blister generation in the insulating film near the weld.

  Therefore, a plurality of short small-diameter coils having a small number of turns are formed by using the enameled wire 10 according to the present embodiment, and the enameled wire terminals of these small-diameter coils are welded and joined together to form a long coil. In electrical equipment, high reliability can be obtained.

  As described above, the present invention is not limited to the above-described embodiment, and it goes without saying that various other things are assumed.

  Next, although this invention is demonstrated based on an Example, this invention is not limited to this Example.

(Example 1)
Polyimide a (Trenice # 3000, manufactured by Toray Industries, Inc .; hereinafter referred to as PIa) paint and polyamideimide (HI-406, manufactured by Hitachi Chemical Co., Ltd .; hereinafter referred to as PAI) paint are combined into PIa resin / PAI resin ( Hereinafter, the mixture was simply mixed so that PIa / PAI) would be 100 parts by weight / 50 parts by weight, and stirred well to obtain a mixed resin paint. 1 part by weight of butylated melamine resin was added to 100 parts by weight of the resin content of the mixed resin paint to obtain an insulating paint.

  After applying this insulating paint on a rectangular copper conductor with a conductor size of 1.5 x 2.5 mm and a chamfer radius of 0.6 mm, it is baked in a hot air circulation type solid baking furnace, and the film thickness is 8 μm. An innermost insulating film (mixed resin insulating layer) was provided. The aforementioned PAI paint alone was applied around the innermost layer insulating film and then baked to provide an outermost layer insulating film having a film thickness of 32 μm. Thereby, a two-layer heat-resistant enameled wire having a total thickness of 40 μm was produced.

(Example 2)
A two-layer heat-resistant enameled wire was produced in the same manner as in Example 1 except that PIa / PAI was 100 parts by weight / 100 parts by weight.

Example 3
A two-layer heat-resistant enameled wire was produced in the same manner as in Example 1 except that PIa / PAI was 100 parts by weight / 25 parts by weight.

Example 4
A two-layer heat-resistant enameled wire was produced in the same manner as in Example 1 except that polyimide b (Pyre ML, manufactured by DuPont; hereinafter referred to as PIb) paint was used instead of the PIa paint.

(Example 5)
Pyromellitic dianhydride as the acid component, 4,4'-diaminodiphenylmethane and 4,4'-diaminodiphenyl ether as the diamine component in a solvent (2-methylpyrrolidone) in a 2 to 1 to 1 molar ratio Dissolved in. This solution was stirred and reacted to prepare a polyimide c (hereinafter referred to as PIc) paint.

  A two-layer heat-resistant enameled wire was produced in the same manner as in Example 1 except that the PIc paint was used instead of the PIa paint.

Example 6
A two-layer heat-resistant enamel wire was produced in the same manner as in Example 1 except that the thickness of the innermost layer insulating film was 5 μm and the thickness of the outermost layer insulating film was 35 μm.

(Example 7)
A two-layer heat-resistant enameled wire was produced in the same manner as in Example 1 except that the thickness of the innermost layer insulating film was 2 μm and the thickness of the outermost layer insulating film was 38 μm.

(Example 8)
1 part by weight of butylated melamine resin was added to 100 parts by weight of the resin component of the same PAI paint as in Example 1 to produce a first insulating paint. This first insulating coating is applied on a rectangular copper conductor with a conductor size of 1.5 x 2.5 mm and a chamfer radius of 0.6 mm, and then baked to provide an innermost insulating film with a film thickness of 8 μm. It was.

  Around this innermost insulating film, a PIa paint and a PAI paint are mixed so that the PIa / PAI is 100 parts by weight / 50 parts by weight, and a mixed resin paint (second insulation paint) that is well stirred is applied. Thereafter, baking was performed to provide an intermediate insulating film (mixed resin insulating layer) having a film thickness of 16 μm.

  The aforementioned PAI paint alone (third insulation paint) was applied around the intermediate layer insulation film, and then baked to provide an outermost insulation film having a film thickness of 16 μm. Thus, a three-layer heat-resistant enameled wire having a total thickness of 40 μm was produced.

Example 9
A three-layer heat-resistant enameled wire was produced in the same manner as in Example 8 except that PIa / PAI was 100 parts by weight / 100 parts by weight.

Example 10
A three-layer heat-resistant enameled wire was produced in the same manner as in Example 8 except that PIa / PAI was 100 parts by weight / 25 parts by weight.

Example 11
A three-layer heat-resistant enameled wire was produced in the same manner as in Example 8 except that the PIb paint was used instead of the PIa paint.

(Example 12)
A three-layer heat-resistant enameled wire was produced in the same manner as in Example 8 except that the PIc paint was used instead of the PIa paint.

(Example 13)
A three-layer heat-resistant enameled wire was produced in the same manner as in Example 8 except that the thickness of the intermediate insulating film was 5 μm and the thickness of the outermost insulating film was 27 μm.

(Example 14)
A three-layer heat-resistant enameled wire was produced in the same manner as in Example 8 except that the thickness of the intermediate insulating film was 2 μm and the thickness of the outermost insulating film was 30 μm.

(Comparative Example 1)
A two-layer heat-resistant enameled wire was produced in the same manner as in Example 1 except that the first insulating paint of Example 8 was used instead of the mixed resin paint of Example 1.

  For each of the enamel wires of Examples 1 to 14 and Comparative Example 1, the linear expansion coefficient at 300 to 400 ° C. of the mixed resin insulating layer was determined. However, for each enameled wire of Examples 1 to 7, the insulating paint constituting the innermost layer insulating film, and for each enameled wire of Examples 8 to 14, the second insulating paint constituting the intermediate layer insulating film, Comparative Example For the enamel wire No. 1, the linear expansion coefficient was measured using the first insulating paint constituting the innermost insulating film.

  Specifically, after each insulating paint is cast (applied) on a glass plate, using a thermostatic bath, the heat history is 80 ° C. × 20 minutes, 200 ° C. × 20 minutes, 300 ° C. × 10 minutes. Each insulating coating was cured by heating to produce an insulating film having a thickness of 30 μm. After each insulating film is mounted on a jig so that the width is 2 mm and the length between chucks is 20 mm, the insulating film is stretched using a thermomechanical analysis measuring device under the conditions of a tensile load of 48 mN and a heating rate of 10 ° C./min. Was measured, and the average linear expansion coefficient from 300 ° C to 400 ° C was measured.

  Moreover, about each enamel wire of Examples 1-14 and the comparative example 1, the external appearance evaluation after TIG welding was performed.

  Appearance evaluation after TIG welding was performed by the following method. First, after each enamel wire was manufactured, each enamel wire was allowed to stand in a constant temperature and humidity chamber of 40 ° C.-95% RH for 30 minutes in consideration of variations due to the environment at the time of evaluation. After that, within 10 minutes after taking out each enamel wire from the thermo-hygrostat, each sample piece of about 5 cm length is cut out from each enamel wire, and 4.5 mm long from one end of each sample piece. The insulating film was peeled off. Place 2.5 mm from the end of one end of each sample piece with a chrome-copper ground rod with a cross-sectional dimension of 1.5 mm x 2.0 mm, and place 1.25 mm from the end of one end of each sample piece. In addition, the tip position of the welding torch was aligned and energized by a TIG welder. The energization conditions were an energization current of 40 A and an energization time of 0.5 seconds.

  Appearance is evaluated by visually observing the surface in the vicinity of the current-carrying part of each sample piece after energization, and the film floating and blister generation are almost unobservable. Thus, foams (blisters) with a diameter of less than 1 mm and a small number of foams of 5 or less were considered to be good, and those with more film floating or blistering were considered bad.

  Table 1 shows the linear expansion coefficient measurement results and the appearance evaluation results after TIG welding.

As shown in Table 1, each enamel wire of Examples 1 to 14 has an insulating layer made of a mixed resin of PI and PAI on a part of the insulating film. Further, the linear expansion coefficient of the mixed resin insulating layer at 300 ° C. to 400 ° C. is 5 × 10 ⁻⁴ / 5 smaller than the linear expansion coefficient (7.2 × 10 ⁻⁴ / ° C.) of the PAI alone by mixing PI. ° C. is adjusted in the following ^{(1.4 × 10 -4 /℃~4.0×10 -4 /} ℃). As a result, each enameled wire of Examples 1 to 14 has sufficient heat resistance in the vicinity of the welded portion, is difficult to be thermally decomposed, and is difficult to be thermally deformed at a high temperature. Therefore, the appearance after TIG welding is good. Or it was almost good.

On the other hand, the enameled wire of Comparative Example 1 in which the insulating film is composed only of PAI without mixing PI has a large linear expansion coefficient of 7.2 × 10 ⁻⁴ / ° C. at 300 to 400 ° C. Therefore, since the heat resistance is insufficient and the film is easily deformed by heat at high temperatures, the appearance after TIG welding was poor.

It is a cross-sectional view of an enameled wire according to a preferred embodiment of the present invention. It is a cross-sectional view showing a modification of the enameled wire of FIG.

Explanation of symbols

10 Enamel wire 11 Conductor 13 Mixed resin insulation layer 14 Outermost insulation layer

Claims (5)

An insulating film composed of at least two insulating layers is formed around the conductor, and the outermost insulating layer is composed of a polyamide-imide film, and a plurality of coil terminals are made of copper by using an electric welding method. In an enameled wire used for an electric device coil formed by heating and melting above the melting point, it is composed of a mixed resin film of polyimide resin and polyamideimide resin on the inner layer side of the outermost insulating layer, and has a temperature of 300 to 400 ° C. An enameled wire comprising a mixed resin insulating layer having a linear expansion coefficient of 5 × 10 ⁻⁴ / ° C. or less . Enameled wire according to claim 1 Symbol placement constituted the mixed resin insulating layer at 20 to 100 parts by weight of the polyamide-imide resin formed by mixing the mixed resin per 100 parts by weight of the polyimide resin. The enameled wire according to claim 1 or 2 , wherein a ratio of a layer thickness of the mixed resin insulating layer to a layer thickness of the entire insulating film is 0.05 or more. An insulating film composed of at least two insulating layers is formed around the conductor, and the outermost insulating layer is composed of a polyamide-imide film, and a plurality of coil terminals are made of copper by using an electric welding method. In an insulating coating used for an enameled wire used for an electrical device coil formed by heating and melting to a temperature equal to or higher than the melting point , a polyimide resin and a polyamide-imide resin are applied to the insulating layer on the inner layer side of the outermost insulating layer. An insulating paint used for an enameled wire, characterized by using a mixed resin that has a linear expansion coefficient of 5 × 10 ⁻⁴ / ° C. or less when mixed at a rate of 300 to 400 ° C. The insulating paint used for the enameled wire according to claim 4 , wherein the mixed resin is obtained by mixing 20 to 100 parts by weight of polyamideimide resin with 100 parts by weight of polyimide resin.

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