JPH04123714A - Heat resistant magnet wire - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a heat-resistant magnet wire.

C. Prior Art and Problems to be Solved by the Invention] Polyimide enameled wires have been widely used as heat-resistant magnet wires.

In order to improve the dielectric breakdown voltage characteristics of such polyimide enameled wires at high temperatures of 200°C or higher, heat-resistant magnet wires are known in which a polyimide enamel paint containing electrolyte-removal clay is coated on the conductor and baked. (Special Publication No. 2-16940).

However, this heat-resistant magnet wire is
There is a drawback that dielectric breakdown occurs when used for a long time in the above condition.

An object of the present invention is to provide a magnet wire with excellent heat resistance that does not cause dielectric breakdown even when used for a long time at high temperatures of 300° C. or higher.

[Means and effects for solving the problems] The heat-resistant magnet wire of the present invention is produced by coating a conductor with a paint containing 1 to 250 parts by weight of boric acid to 100 parts by weight of the resin content of a polyimide enamel paint. It becomes baked.

In the present invention, the resin component of the polyimide-based enamel paint is a polyamic acid resin in the paint state, and when applied to a conductor,
Baking sometimes converts it into polyimide resin. Since it effectively combines with metaboric acid during this conversion process, it is presumed that heat resistance is synergistically improved and that it exhibits excellent dielectric breakdown voltage characteristics at high temperatures.

The polyimide enamel paint used in the present invention is obtained by reacting an aromatic tetracarboxylic dianhydride with an aromatic polyamine in a polar solvent such as N-methylpyrrolidone, dimethylacetamide, or dimethylformamide.

Examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride, 3.3-. 4.4-1Benzophenonetetracarboxylic dianhydride and the like. As the aromatic polyamine, 4,4'-diaminodiphenyl ether, 4.
Examples include 4-diaminodiphenylmethane and 1,3.5-triaminobenzene.

Commercially available polyimide enamel paints include Pile ML from DuPont, Trenice #2000 from Toshisha, U Varnish 8 from Ube Industries, and TVE5051 from Toshiba Chemical. The resin component of these polyimide-based enamel paints in the paint state is polyamic acid resin, and this polyamic acid resin is sometimes converted to polyimide resin during high-temperature enamel baking.

Examples of boric acid include metaboric acid, orthoboric acid, tetraboric acid, and boron oxide, among which metaboric acid is preferred from the viewpoint of ease of mixing with a solvent.

The amount of boric acid blended in the present invention is 1 to 250 parts by weight based on 100 parts by weight of the resin content of the polyimide enamel paint. If it is less than 1 part by weight, heat resistance will not improve, and if it exceeds 250 parts by weight, flexibility will sharply decrease. The preferred blending amount of boric acid is 10 to 100 parts by weight per 100 parts by weight of the resin content of the polyimide enamel paint.

In addition, in the paint applied to the conductor, 5 to 10 parts of a polar solvent such as N-methylpyrrolidone, dimethylacetamide, dimethylformamide, etc. is added to 100 parts by weight of the resin.
It is preferable to contain 0 parts by weight because uniform mixing can be achieved.

[Example] Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Example 1 Polyimide enamel paint (DuPont Pile ML,
1 part of metaboric acid per 100 parts by weight of resin (same below)
After creating a blended paint containing 0 parts by weight and applying the blended paint onto a copper conductor wire with a conductor diameter of 1°0 x φ, the excess paint was squeezed out with a die, and the mixture was heated at a furnace temperature of 450°C and an effective furnace length of 5 m. The wire was baked by passing through a baking furnace at a rate of 20 m/min to obtain a magnet wire with a coating thickness of 40 μm.

Example 2 Example 1 except that 500 parts by weight of metaboric acid was added to 100 parts by weight of the resin content of the polyimide enamel paint.
In the same manner as above, a magnet wire with a coating thickness of 40 μm was obtained.

Example 3 A magnet wire with a coating thickness of 40 μm was obtained in the same manner as in Example 1, except that 130 parts by weight of metaboric acid was added to 100 parts by weight of the resin content of the polyimide enamel paint.

Comparative Example 1 A magnet wire with a coating thickness of 40 μm was obtained in the same manner as in Example 1, except that 0.5 parts by weight of metaboric acid was added to 100 parts by weight of the resin content of the polyimide enamel paint.

Comparative Example 2 A magnet wire with a coating thickness of 40 μm was obtained in the same manner as in Example 1, except that 260 parts by weight of metaboric acid was blended with 100 parts by weight of the resin content of the polyimide enamel paint.

Next, the dielectric breakdown voltage characteristics and flexibility of the magnet wires of Examples and Comparative Examples obtained as described above were measured according to the following method. The results are shown in Table 1.

(1) Dielectric breakdown voltage characteristics Dielectric breakdown voltage was measured from two JIS C3003 (1984) standards in accordance with the law. Measurements were made on the heated magnet wire and the heated magnet ear (heated at 350° C. for 10 days and then returned to room temperature).

(2> Flexibility J Is C3003 (1984): Measured by self-wrapping in accordance with JIS C3003 (1984). Those with no clarification on the surface were designated as O, and those with no clarification were designated as O.

Table 1 As is clear from Table 1, the σ magnet wires of Examples 1 to 3 had excellent dielectric breakdown voltage properties and flexibility after heating.

On the other hand, the magnet wire of Comparative Example 1 did not have improved heat resistance and had poor dielectric breakdown voltage characteristics after heating because the amount of metaboric acid in the applied paint was small. Comparative example 2
The magnet wire had poor flexibility because there was too much metaboric acid in the paint applied.

[Effects of the Invention] As described above, the heat-resistant magnet wire of the present invention has a
Since the dielectric breakdown voltage characteristics do not deteriorate even when heated at 0° C. or higher for a long time, it can be used continuously at high temperatures of 300° C. or higher, making it extremely practical.

Patent applicant Tara Riden Cable Co., Ltd. Haka 1 representative Patent attorney Tsuta 1) Sho Kobaka 1 person

Claims (2)

[Claims] 1. A heat-resistant magnet wire made by applying and baking a paint containing 1 to 250 parts by weight of boric acid to 100 parts by weight of the resin of a polyimide enamel paint onto a conductor. 2. The heat-resistant magnet wire according to claim 1, wherein the boric acid is metaboric acid.