JPH1060084A - Epoxy resin composition and coil insulated with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition balancing adhesion with crack resistance and excellent in stability with a lapse, and to provide a coil insulated with the epoxy resin composition. SOLUTION: This epoxy resin composition consists essentially of (a) 100 pts.wt. bisphenol-type liquid epoxy resin, (b) 5-30 pts.wt. acrylonitrile-butadiene copolymer having an end group modified by a carboxyl group and (c) 5-15 pts.wt. reaction product of an imidazole with a bisphenol-type liquid epoxy resin and the coil is insulated by using the epoxy resin composition as a vanish.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition and a coil insulated using the epoxy resin composition.

[0002]

2. Description of the Related Art A coil used for a high-voltage generating electric device such as a rotary machine, a transformer for ignition, a transformer for a microwave oven, and the like, which undergoes large vibrations during operation, such as a motor for a power tool, a motor for a vehicle, and a generator. For the insulation treatment, an acid anhydride-curable epoxy resin varnish is generally used.
This is because the cured product of the acid anhydride-curable epoxy resin varnish has excellent mechanical properties at high temperatures and high voltage properties (arc resistance and tracking resistance).

[0003]

In recent years, these electric devices have been required to have higher performance and reliability than ever before. In particular, in a rotating machine that is subject to large vibrations during operation, if the coil ends and the binding yarns of the coils are not sufficiently fixed, it is necessary to prevent the vibrations from moving the coil ends and the enameled wires of the coils. Must. Therefore, when an insulating treatment is performed using a high-strength insulating varnish having improved adhesiveness, particularly at high temperatures, cracks may occur in a cured insulating varnish due to expansion and contraction due to a temperature difference before and after the operation of the electric device. . In addition, acid anhydride-curable epoxy resin varnish has poor aging stability, the pot life at 25 ± 10 ° C. is usually about 10 to 20 hours, and in order not to waste the prepared varnish, Each time the acid anhydride and the epoxy resin as the curing agent were used, they had to be prepared in consideration of the amount used.

SUMMARY OF THE INVENTION The present invention provides an epoxy resin composition which balances adhesion and crack resistance and has excellent aging stability as a varnish, and a coil insulated using the epoxy resin composition. The purpose is to provide.

[0005]

The present invention comprises (a) 100 parts by weight of a bisphenol type liquid epoxy resin, (b) 5 to 30 parts by weight of a terminally carboxyl-modified acrylonitrile-butadiene copolymer, and (c) an imidazole and bisphenol type. An epoxy resin composition containing 5 to 15 parts by weight of a reaction product with a liquid epoxy resin as an essential component.

The epoxy resin composition is used as a varnish,
Insulate the coil. Here, the insulation treatment means an operation of impregnating the coil with a varnish of an epoxy resin composition and curing the coil.

Bisphenol type liquid epoxy resin 100
When the blending amount of the terminal carboxyl-modified acrylonitrile-butadiene copolymer is less than 5 parts by weight, the cured product is liable to crack, and when it exceeds 30 parts by weight, the adhesive strength is poor. If the amount of the reaction product of imidazole and the bisphenol-type liquid epoxy resin is less than 5 parts by weight based on 100 parts by weight of the bisphenol-type liquid epoxy resin, it takes a long time to cure. And the varnish of the epoxy resin composition hardens on the surface of the coil before penetrating into the coil. From such a viewpoint, (a) 100 parts by weight of a bisphenol-type liquid epoxy resin, and (b) a terminal carboxyl-modified acrylonitrile-butadiene copolymer 1
It is preferable to use 0 to 20 parts by weight and 5 to 10 parts by weight of (c) a reaction product of imidazole and a bisphenol-type liquid epoxy resin.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The bisphenol type liquid epoxy resin used as an essential component in the present invention includes bisphenol A, bisphenol F or bisphenol AD.
And glycidyl ethers derived from epichlorohydrin and epichlorohydrin, and so-called epi-bis type epoxy resins such as derivatives thereof. Liquid epoxy resins are preferable.

The terminal carboxyl-modified acrylonitrile-butadiene copolymer used as an essential component in the present invention includes, for example, CTBN1300X13, CTBN
1300X9 (all trade names of Ube Industries, Ltd.), and their acrylonitrile content is 10 to 3
0% by weight.

The reaction product of imidazole and bisphenol type liquid epoxy resin used as an essential component in the present invention is, for example, 50 parts after charging 2-phenylimidazole and bisphenol A type epoxy resin at a ratio of 2 mol to 1 mol. Cureduct P-0505 (trade name of Shikoku Chemicals Co., Ltd.), which is a reaction product obtained by reacting at 2 ° C. for 2 to 5 hours.

In addition to (a) a bisphenol-type liquid epoxy resin, (b) a terminal carboxyl-modified acrylonitrile-butadiene copolymer and (c) a reaction product of imidazole and a bisphenol-type liquid epoxy resin, a coupling agent, A varnish is prepared by blending a foaming agent, a coloring agent and the like, and the coil is impregnated and cured by means such as drip. For example, after dripping while rotating a coil preheated at 70 to 120 ° C. for 0.5 to 2 hours,
The epoxy resin is cured by heating at 20 to 150 ° C. for 0.5 to 2 hours.

[0012]

The present invention will be described in more detail with reference to the following examples. Bisphenol A type epoxy resin (using EPON828 (trade name) manufactured by Yuka Shell Epoxy Co., Ltd.) 100 parts (parts by weight, the same applies hereinafter), terminal carboxyl-modified acrylonitrile-butadiene copolymer (CTBN1300X9 manufactured by Ube Industries, Ltd.) 15 parts (using trade name) and 10 parts of a reaction product of imidazole and a bisphenol-type liquid epoxy resin (using Cure Duct P-0505 (trade name) manufactured by Shikoku Chemicals Co., Ltd.) are mixed together to form an epoxy resin. A composition was obtained.

Comparative Example 1 An epoxy resin composition was obtained in the same manner as in Example except that the terminal carboxyl-modified acrylonitrile-butadiene copolymer was not used.

Comparative Example 2 An epoxy resin composition was obtained in the same manner as in Example except that 10 parts of a reaction product of imidazole and a bisphenol type liquid epoxy resin were replaced with 5 parts of 2-ethyl-4-methylimidazole.

The obtained epoxy resin composition was examined for adhesive strength, crack resistance, and aging stability. Table 1 shows the results. Each test method is as described below.

(1) Adhesive force Measured according to the JIS C 2105 Strucker adhesive force test. That is, a diameter of 2.0 mm and a length of 80 mm
And a 40 mm polyester wire as a test piece, and apply the obtained epoxy resin composition to the test piece.
For 0.5 hour to obtain a test specimen. Adhesion strength is 100
The measurement was carried out for each of five test specimens at ° C, 120 ° C, and 150 ° C, and the average value was shown.

(2) Crack resistance A 2.0 mm-diameter polyester wire cut to an appropriate length so as to be laid in a metal petri dish is 60 mm in diameter.
Was spread in a metal Petri dish, and 5 g of the obtained epoxy resin composition was poured into the metal Petri dish and heated at 110 ° C. for 3 hours to obtain a test specimen. The obtained test specimen was kept at -50 ° C for 0.5 hour, and then kept at 135 ° C for 0.5 hour.
As a cycle, a heat cycle test of 20 cycles was performed, and the occurrence of cracks was visually observed.

(3) Daily Stability Investigation was carried out according to the gelation time test (test tube method) of JIS C 2105. That is, the obtained epoxy resin composition was put into a test tube, held in an oil bath at 50 ° C., and the presence or absence of gelation was observed at predetermined time intervals, and the time until gelation was examined.

[0019]

Table 1 Example Comparative Example 1 Comparative Example 2接着 Adhesion 100 ° C 580 580 580 (N) 120 ° C 550 560 570 150 ° C 450 450 460４ ─────────────────── Crack generation No Yes No ────────────────────────── ─── Daily stability> 30 days> 30 days <1 day ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

From the data shown in Table 1, the epoxy resin compositions of Examples, Comparative Examples 1 and 2 have almost the same adhesive strength, and the epoxy resin compositions of Examples have heat cycle tests. It can be seen that no cracks were generated and the aging stability was extremely good. On the other hand, for the epoxy resin composition of Comparative Example 1 in which the terminal carboxyl-modified acrylonitrile-butadiene copolymer was not blended, cracks occurred in the heat cycle test, and the reaction product of imidazole and the bisphenol-type liquid epoxy resin was replaced. About the resin composition of the comparative example blended with 2-ethyl-4-methylimidazole,
It turns out that the stability over time is extremely poor.

[0021]

The epoxy resin composition of the present invention has a cured product having excellent adhesive strength at high temperatures and excellent crack resistance.
As a coil for rotating equipment to which large vibration is applied during operation,
The reliability of fixing the coil end and the binding yarn can be improved. Also, since the aging stability is good, it greatly contributes to simplifying the working process.

Continued on the front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI Technical display location H01B 3/40 H01B 3/40 H01F 27/32 H01F 27/32 A

Claims (2)

[Claims] 1) 100 parts by weight of a bisphenol type liquid epoxy resin, (b) 5 to 30 parts by weight of a terminal carboxyl-modified acrylonitrile-butadiene copolymer and (c) a reaction product 5 of imidazole and a bisphenol type liquid epoxy resin. An epoxy resin composition containing 15 to 15 parts by weight as an essential component. 2. A coil which is insulated using the epoxy resin composition according to claim 1.