JPH10289622A - Silica finely dispersed polyimide enameled wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wire with a specific heat resistance and be superior in flexibility, winding performance, and adhesion to a conductor by coating a degenerated polyimide precursor solution formed by completely dissolving the whole components of tetraalkoxysilane and pure water into the polyimide precursor solution on a conductor, and baking it. SOLUTION: Solution has all the components completely dissolved therein so that the stability of the solution becomes superior. Polyamide acid solution is used as precursor solution, tetramethoxysilane, etc., is used for tetraalkoxysilane, and dispersant such as silane coupling agent, etc., is added thereto for enhancing specific characteristics. A copper wire of an conductor 1 is applied and baked with the solution to be formed into an enamel film 2 and the alkoxysilane and the pure water are sol/gel reacted to each other to form silica particulates. The silica particulates are uniformly dispersed in the polyimide resin. The heating resistance is set to 250 deg.C or more/20,000 hrs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silica finely dispersed polyimide enameled wire. More specifically, the present invention relates to a silica finely dispersed polyimide enameled wire formed by applying and baking a modified polyimide precursor solution on a conductor.

[0002]

2. Description of the Related Art In recent years, progress in industrial technology has been remarkable. In the field of electrical equipment, the development of higher-performance electrical equipment is also required. As a matter of course, enameled wires for wound coils of electrical equipment that require such advanced characteristics are required to have even more excellent various characteristics.
For example, in the aerospace industry, the energy industry, the nuclear industry, the automobile equipment field, and the like, enameled wires having even higher heat resistance are required.

At present, 155 ° C to 180 ° C class / 20,
As the heat-resistant enameled wire of 000 hrs, a polyesterimide enameled wire, and a 180 ° C. to 200 ° C. class / 2
Polyamide imide enameled wire is used as the heat-resistant enamel wire of 000 hrs, and polyimide enamel wire is used as the heat-resistant enamel wire of 220 to 240 ° C. class / 20,000 hrs.

[0004] However, in the aerospace industry, the energy industry, the nuclear industry, the automobile equipment field, etc., heat-resistant enameled wires having a temperature of 250 ° C. or more / 20,000 hrs have been required.

[0005] Such a currently used heat-resistant enameled wire has a temperature of 250 ° C or more / 20,000 hrs.
Can not meet the heat resistance requirement.

Incidentally, addition of an inorganic substance to a polyimide precursor solution is known in Japanese Patent Publication No. 42-19350. An inorganic substance-added polyimide enamel wire formed by applying an inorganic substance-added polyimide precursor solution obtained by adding an inorganic substance to the polyimide precursor solution, for example, silica, alumina, magnesia, titanium oxide, mica powder, or the like, and baking the conductor. Is known to have excellent heat resistance.

However, an inorganic substance-added polyimide precursor solution obtained by adding silica, alumina, magnesia, titanium oxide, mica powder, or the like, is essentially a silica, alumina, magnesia, titanium oxide, mica powder that is not dissolved in the polyimide precursor solution. The disadvantage is that the stability of the solution is extremely poor because the powder and the like easily settle. Therefore, the workability of producing an enameled wire for coating and baking an inorganic substance-added polyimide precursor solution having poor solution stability on a conductor is poor.

Further, silica for improving heat resistance,
An inorganic substance-added polyimide enameled wire formed by applying and baking an inorganic substance-added polyimide precursor solution on a conductor by increasing the addition amount of alumina, magnesia, titanium oxide, mica powder, etc. has an improved heat resistance. However, there is a problem in that the inorganic substance deteriorates the appearance of the enameled wire, and further, the flexibility, winding property, adhesion to a conductor and the like are significantly deteriorated.

For this reason, 250 ° C. or more / 20,000
There is a demand for a heat-resistant enameled wire having heat resistance of 0 hrs and excellent flexibility, winding property, adhesion to a conductor, and the like.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of such a point, and an object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to achieve a temperature of 250.degree.
000hrs heat resistance, flexibility, winding property,
An object of the present invention is to provide a heat-resistant enameled wire having excellent adhesion to a conductor and the like.

[0011]

The gist of the present invention is that a modified polyimide precursor solution obtained by dissolving tetraalkoxysilane and pure water in a polyimide precursor solution is coated on a conductor and baked. And silica finely dispersed polyimide enameled wire.

A modified polyimide precursor solution obtained by dissolving tetraalkoxysilane and pure water in a polyimide precursor solution is a solution in which all components are completely dissolved, and has excellent solution stability.

Because of the excellent solution stability, the modified polyimide precursor solution has excellent workability of coating and baking on a conductor. The modified polyimide precursor solution is applied on a conductor and baked, whereby the blended tetraalkoxysilane and pure water undergo a sol-gel reaction to produce silica fine particles. The produced silica fine particles are uniformly dispersed in the polyimide resin, whereby a silica finely dispersed polyimide enameled wire having a uniform appearance and excellent flexibility and heat resistance can be obtained.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a polyimide precursor solution is a polyamic acid solution. Such a polyamic acid solution is obtained by reacting 4,4'-diaminodiphenyl ether with pyromellitic anhydride in a polar organic solvent such as N-methylpyrrolidone, dimethylacetamide, dimethylformamide and the like. Commercially available polyimide precursor solutions include Pyre M from DuPont.
L, Torayne 3000, etc. of Toray Industries.

In the present invention, the tetraalkoxysilane includes tetramethoxysilane, tetraethoxysilane and the like.

In the present invention, a dispersant such as a silane coupling agent may be added to improve special characteristics.

[0017]

The examples and comparative examples of the silica finely dispersed polyimide enamel wire of the present invention will be described.

(Example 1) Pyre ML manufactured by DuPont
To 1,500 g of the paint, 305 tetraethoxysilane was added.
g of pure water and 225 g of pure water were added thereto, and the mixture was stirred and completely dissolved by a homogenizer to obtain a modified polyimide precursor solution of Example 1.

Next, the thus obtained modified polyimide precursor solution of Example 1 was coated on a copper wire having a conductor diameter of 0.5 mm and baked, and the silica fine dispersion of Example 1 having an enamel film thickness of 20 μm was obtained. A polyimide enameled wire was obtained.

FIG. 1 shows a cross section of the silica finely dispersed polyimide enameled wire of Example 1 thus obtained, wherein 1 is a conductor and 2 is an enamel coating.

(Embodiment 2) Torayness 3000 manufactured by Toray Industries, Inc.
The silica finely dispersed polyimide enameled wire of Example 2 was obtained in the same manner as in Example 1 except for using.

Example 3 Tetramethoxysilane was added to 23
A silica finely dispersed polyimide enameled wire of Example 3 was obtained in the same manner as in Example 1 except that the amount was 0 g.

(Comparative Example 1) Pyre ML manufactured by DuPont
Apply paint on copper wire with conductor diameter of 0.5mm, bake it,
A polyimide enameled wire of Comparative Example 1 having an enamel coating thickness of 20 μm was obtained. (Comparative Example 2) Torayness 300 of Toray Industries, Inc.
A polyimide enameled wire of Comparative Example 2 was obtained in the same manner as Comparative Example 1 except that 0 was used.

(Comparative Example 3) Pyre ML manufactured by DuPont
To 2,000 g of the coating material, 100 g of alumina particles having an average particle size of 1 μm were added, and the mixture was stirred with a homogenizer to obtain an alumina-dispersed polyimide precursor solution of Comparative Example 3.

Next, the thus obtained alumina-dispersed polyimide precursor solution of Comparative Example 3 was mixed with a conductor having a diameter of 0.5 mm.
On copper wire, baking, enamel film thickness 20μ
m of the alumina-dispersed polyimide enameled wire of Comparative Example 3 was obtained.

(Characteristic test) Next, a characteristic test was performed on the enameled wires of the examples and the comparative examples thus obtained.

The characteristic test was performed according to JIS-C3003.

Table 1 shows the results of the characteristic tests thus obtained.

[0029]

[Table 1]

As can be seen from Table 1, the polyimide enameled wire of Comparative Example 1 has a heat resistance of 245 ° C./20,000 hrs, and a heat resistance of 250 ° C. or less / 20,000 hrs. Also, the polyimide enameled wire of Comparative Example 2 was 245 ° C.
/ Heat resistance of 20,000 hrs, 250 ° C or less /
It has a heat resistance of 20,000 hrs.

In Comparative Example 3, the coating was inferior in stability and separated, and the obtained alumina-dispersed polyimide enameled wire also exhibited heat resistance of 265 ° C./20,000 hrs, but the flexibility passed 10-fold diameter winding. The level is poor, and the abrasion resistance and adhesion to the conductor are also poor.

On the other hand, Examples 1 to 3 have excellent paint stability, and the obtained silica finely dispersed polyimide enameled wire also has excellent heat resistance of 280 ° C./20,000 hrs, and further has flexibility and adhesion. Also showed excellent results.

[0033]

The paint for silica-dispersed polyimide enameled wire of the present invention has excellent paint stability, and has excellent coating workability when applied and baked on a conductor, and is further obtained by coating and baking. The silica finely dispersed polyimide enameled wire has excellent heat resistance of 280 ° C./20,000 hrs, and is also excellent in flexibility and adhesion, and is industrially useful.

[Brief description of the drawings]

FIG. 1 shows a cross section of a silica finely dispersed polyimide enameled wire of Example 1 of the present invention.

[Explanation of symbols]

 1 conductor 2 enamel coating

Claims (2)

[Claims] 1. A silica finely dispersed polyimide enameled wire obtained by applying and baking a modified polyimide precursor solution obtained by dissolving tetraalkoxysilane and pure water in a polyimide precursor solution on a conductor. 2. A silica finely dispersed polyimide enameled wire according to claim 1, wherein a silane coupling agent is additionally added to the modified polyimide precursor solution.