JPH093367A - Composition for electrical insulation and insulated wire - Google Patents

Abstract

PURPOSE: To obtain a resin composition (especially a varnish for enamel wires) for electrical insulation, excellent in hydrolysis resistance and a wire insulated therewith. CONSTITUTION: This resin composition for electrical insulation prepared by mixing 100 pts.wt. resin component of a synthetic resin coating material for electrical insulation with 0.5-10 pts.wt. monocarbodiimide and an insulated wire prepared by coating a conductor with this composition directly or through another insulator and baking the composition are prepared.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for electrical insulation and an insulated wire, and more particularly to a resin composition for electrical insulation which is low in cost and excellent in hydrolysis resistance, and an insulated wire using the same.

[0002]

2. Description of the Related Art Conventionally, insulated electric wires (hereinafter abbreviated as enamel wires) obtained by applying a synthetic resin coating such as polyvinyl formal, polyurethane, polyester, polyester imide, or polyamide imide on a conductor and baking it have their respective characteristics. It is used in various applications such as motors and transformers. These applications are roughly divided into cases in which the enameled wire is wound and molded and then molded with a molding resin, and cases in which it is not molded or treated with an impregnated varnish.

In recent years, with the severer conditions of use of electric equipment, there has been a strong demand for improving the heat resistance of enameled wires. In particular, in the case of an enameled wire used as a mold, not only heat deterioration but also the influence of hydrolysis due to water contained in the mold resin and the filler is a serious problem. In such a case, a polyamide-imide enameled wire, which is excellent in heat resistance and hydrolysis resistance, is usually used, but in terms of price, coating workability and peeling characteristics of the resulting enameled wire, it is used in all applications. It is currently not used in.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks of the prior art and provides a resin composition for electrical insulation (especially varnish for enameled wire) having excellent hydrolysis resistance and an insulated wire using the same. To do.

[0005]

Means for Solving the Problems As a result of intensive studies in view of the above problems, the present inventors have found that hydrolysis resistance can be improved by adding a monocarbodiimide compound to a synthetic resin coating, Arrived That is,
The present invention relates to a resin composition for electrical insulation (particularly a varnish for enameled wire) obtained by mixing 0.5 to 10 parts by weight of monocarbodiimide with 100 parts by weight of a resin component of a synthetic resin coating for electrical insulation, and a conductor for the same. The present invention relates to an insulated electric wire which is applied directly onto or through another insulating material and baked.

The synthetic resin paint for electrical insulation used in the present invention is not particularly limited, and contains a hydrolyzable resin. Examples of such resins include polyurethanes, polyesters, polyesterimides and the like, which are composed of a resinous polyol such as polyvinyl formal or polyester polyol and an isocyanate compound which may be blocked. In addition, there are polyamideimide resin and polyimide resin obtained by reacting tricarboxylic acid anhydride or its derivative having three carboxyl groups such as trimellitic anhydride and a diamine as an essential component, but the low price point Therefore, the above resins are preferable. The synthetic resin paint for electrical insulation is cresol, phenol, xylene,
The resin is dissolved in an organic solvent such as a high boiling point hydrocarbon such as solvent naphtha, but for polyamide-imide resin and polyimide resin, N-methyl-
2-pyrrolidone, N, N-dimethylacetamide, N,
A polar organic solvent such as N-dimethylformamide is used, and xylene or the like is used in a mixture with these polar organic solvents as needed. The synthetic resin paint for electrical insulation,
As an additive, a leveling agent, a coloring agent, etc. may be contained. In particular, when polyester or polyester imide is used, tetraalkyl titanate such as tetrabutyl titanate is used as a curing agent in an amount of 0.1 to 1 with respect to the resin.
It is preferable to contain 0% by weight. The synthetic resin paint for electrical insulation preferably has a resin content of 10 to 55% by weight.

Examples of the monocarbodiimide compound used in the present invention include N, N'-di-o-toluylcarbodiimide, N, N'-diphenylcarbodiimide,
Examples thereof include N, N'-di-2,6-dimethylphenylcarbodiimide, N, N'-bis (2,6-diisopropylphenyl) -carbodiimide and the like. Of these, N, N'-bis (2,6-diisopropylphenyl) -carbodiimide is particularly preferable because it has little thermal decomposability during baking of the electrically insulating coating. The monocarbodiimide compound can be obtained by heating the corresponding isocyanate compound using sodium methylate or sodium phenolate as a catalyst to cause condensation, and then distilling to obtain the desired carbodiimide. For example, N,
N'-bis (2,6-diisopropylphenyl) -carbodiimide is prepared by reacting 2,6-diisopropylphenylisocyanate with sodium methylate as a catalyst to give about 20
It is obtained by condensation at 0 ° C. and then distillation.

In the present invention, the addition amount of the monocarbodiimide compound is 0.5 to 10 parts by weight, preferably 1 to 8 parts by weight, relative to 100 parts by weight of the resin component of the synthetic resin coating for electrical insulation. The amount of monocarbodiimide compound added is 0.5
If it is less than 10 parts by weight, the effect of the present invention is small, and if it exceeds 10 parts by weight, the appearance and other general properties of the obtained enameled wire are adversely affected. The addition method of the monocarbodiimide compound is not particularly limited, but from the viewpoint of not affecting the synthetic process of the synthetic resin, it is preferable to add the monocarbodiimide compound after the final step of the synthesis or after coating, and the monocarbodiimide compound as it is. , Or dissolved in an appropriate organic solvent such as cresol or xylene, and added. The insulated wire is
It can be obtained by applying the resin composition for electrical insulation of the present invention onto a conductor directly or via another insulator by a known method and baking it.

[0009]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Example 1 Polyvinyl formal varnish, WM-445U-28
(Hitachi Chemical Co., Ltd. product name, resin content 28% by weight) 100
1.87 parts by weight of a 30% by weight xylene solution of N, N'-di-o-toluylcarbodiimide was added to and dissolved in parts by weight to obtain a resin composition for electrical insulation.

Example 2 100 parts by weight of polyurethane varnish, WD-437K-49 (trade name, manufactured by Hitachi Chemical Co., Ltd., resin content 49% by weight),
0.98 parts by weight of N, N'-diphenylcarbodiimide was added as it was and dissolved to obtain a resin composition for electrical insulation.

Example 3 100 parts by weight of polyester varnish, WH-4050-40 (trade name of Hitachi Chemical Co., Ltd., resin content 40% by weight),
N, N'-bis (2,6-diisopropylphenyl)-
8 parts by weight of a 10% by weight carbodiimide cresol solution was added and dissolved to obtain a resin composition for electrical insulation.

Example 4 100 parts by weight of polyesterimide varnish, HF-4050-44 (trade name, manufactured by Hitachi Chemical Co., Ltd., resin content: 44% by weight), was mixed with N, N'-di-2,6-dimethylphenylcarbodiimide. A 20 wt% xylene solution (4.4 parts) was added and dissolved to obtain a resin composition for electrical insulation.

Comparative Examples 1 to 4 Polyvinyl formal varnish WM-445U-28 and polyurethane varnish WD used in Examples 1 to 4, respectively.
-437K-49, polyester varnish WH-4050
-40 and polyester imide varnish HF-4050
-44 was used as it was as a resin composition for electrical insulation.

<Test Example> Examples 1 to 4 and Comparative Examples 1 to 1
Using the resin composition for electrical insulation obtained in 4 above, coating and baking was performed on a copper wire having a diameter of 1 mm so that the film thickness was about 30 μm, to produce an enamel wire. Using the obtained enamel wire, two twisted wires were produced according to JIS C3003, and used as a test piece. Then, the test piece was placed in an autoclave having an internal volume of 670 ml, 0.67 g of pure water was added, and then the air inside the autoclave was replaced with nitrogen to seal it. This autoclave was kept at 150 ° C. for 15 hours and cooled, and then the dielectric breakdown voltage of the test piece was measured, and the dielectric breakdown voltage retention rate was calculated from the initial value. The results are shown in Table 1. Further, the coating workability of the composition and the general characteristics of the obtained enamel wire were good.

[0015]

[Table 1] From Table 1, it is clear that the electrical insulating resin composition of the present invention has excellent hydrolysis resistance.

[0016]

EFFECTS OF THE INVENTION According to the resin composition for electric insulation in the first aspect, it is possible to obtain an enameled wire excellent in hydrolysis resistance. The insulated wire according to the second aspect is excellent in hydrolysis resistance due to water such as resin and filler when molded with a mold resin.

Claims (2)

[Claims] 1. A resin component 100 of a synthetic resin paint for electrical insulation.
Monocarbodiimide compound 0.5 to 10 parts by weight
A resin composition for electrical insulation, which is obtained by adding 1 part by weight. 2. An insulated electric wire obtained by applying the resin composition for electrical insulation according to claim 1 on a conductor directly or via another insulator, and baking it.