EP-4737499-A1 - CURABLE EPOXY COMPOSITION FOR DYNAMO-ELECTRIC MACHINES

Abstract

An object of the present disclosure is to provide a curable epoxy composition for a rotatory electric machine that can easily adhere to PEEK resin and can suppress delamination during use. The epoxy composition for a rotatory electric machine of an embodiment of the present disclosure contains an epoxy compound (A), an acid anhydride-based curing agent (B), and an amine-based curing accelerator (C), is liquid at 25°C, and has a viscosity at 25°C of 3000 mPa·s or less and an adhesive strength to PEEK resin of 2.5 N/cm 2 or more when cured. In the curable epoxy composition for a rotatory electric machine, a viscosity increase rate before and after a storage test performed under conditions of a temperature of 23 ± 5°C and a humidity of 50 ± 5% for 41 days is preferably 20000% or less.

Inventors

• MIKI, Ayano

Assignees

• Daicel Corporation

Dates

Publication Date

20260506

Application Date

20240624

Claims (6)

1. A curable epoxy composition for a rotatory electric machine, the curable epoxy composition containing an epoxy compound (A), an acid anhydride-based curing agent (B), and an amine-based curing accelerator (C), the curable epoxy composition being liquid at 25°C, and having a viscosity at 25°C of 3000 mPa·s or less and an adhesive strength to PEEK resin of 2.5 N/cm 2 or more when cured.
2. The curable epoxy composition for a rotatory electric machine according to claim 1, wherein a viscosity increase rate before and after a storage test performed under conditions of a temperature of 23 ± 5°C and a humidity of 50 ± 5% for 41 days is 20000% or less.
3. The curable epoxy composition for a rotatory electric machine according to claim 1 or 2, wherein the curable epoxy composition has a glass transition temperature of 170°C or higher when cured.
4. A cured product of the curable epoxy composition for a rotatory electric machine described in claim 1 or 2.
5. A stator for a rotatory electric machine, the stator comprising the cured product described in claim 4, and the cured product being formed in a manner covering a stator coil.
6. A rotor for a rotatory electric machine, the rotor comprising the cured product described in claim 4, and the cured product covering a winding of the rotor.

Description

Technical Field The present disclosure relates to a curable epoxy composition for use in rotatory electric machines. More particularly, in an embodiment, the present disclosure relates to a curable epoxy composition for forming a cured product for use in a stator or rotor in rotatory electric machines. The present application claims priority to Japanese Patent Application No. 2023-108870 filed in Japan on June 30, 2023, the content of which is incorporated herein by reference. Background Art Epoxy resins are used as a resin (encapsulating material) for encapsulating an optical semiconductor element in an optical semiconductor apparatus, a resin for molded coil applications in which a coil such as an ignition coil is impregnated and casted, a resin for fiber reinforcement, a resin for a rotatory electric machine (such as an insulating material, an adhesive resin for fixation of a permanent magnet, or a filler for a gap), and the like (for example, see Patent Documents 1 to 2). In particular, a polyamide-imide resin having high heat resistance has been used as an insulating layer of a winding for a rotatory electric machine, but as a measure for high voltage resistance (PDIV) in order to achieve, for example, high-speed charging, Replacement of the insulating layer made of the polyamide-imide resin with a PEEK resin having higher voltage resistance is in progress. Citation List Patent Document Patent Document 1: JP 2017-199566 APatent Document 2: JP 2021-183687 APatent Document 3: JP 2020-524190 T Summary of Invention Technical Problem However, the PEEK resin has a problem in adhesion properties to the epoxy resin due to the properties of the PEEK resin. There has been proposed a method for improving the composition of the PEEK resin to improve adhesion properties to the epoxy resin, as in Patent Document 3, but the method is insufficient. Therefore, when subjected to motor vibration, delamination occurs between the epoxy resin and the PEEK resin, and the delaminated epoxy resin and a winding, or windings themselves repeatedly collide with each other in association with the motor vibration, which causes wear of the PEEK resin protecting the winding, and thus, insulating properties are deteriorated. Accordingly, an object of the present disclosure is to provide a curable epoxy composition for a rotatory electric machine, which can easily adhere to the PEEK resin and can suppress delamination during use. Solution to Problem As a result of intensive studies to achieve the above object, the inventor of the present disclosure has found that a curable epoxy composition for a rotatory electric machine, the curable epoxy composition containing an epoxy compound, an acid anhydride-based curing agent, and an imidazole-based curing accelerator and exhibiting a specific viscosity and an adhesive strength, can easily adhere to PEEK resin and can suppress delamination during use. The present disclosure relates to what has been completed based on these findings. The present disclosure provides a curable epoxy composition for a rotatory electric machine, the curable epoxy composition containing an epoxy compound (A), an acid anhydride-based curing agent (B), and an amine-based curing accelerator (C), the curable epoxy composition being liquid at 25°C, and having a viscosity at 25°C of 3000 mPa·s or less and an adhesive strength to PEEK resin of 2.5 N/cm2 or more when cured. The curable epoxy composition for a rotatory electric machine is liquid at 25°C, and has a viscosity at 25°C of 3000 mPa·s or less, and thus has excellent impregnation properties and enables easy adhesion while suppressing defects. When the curable epoxy composition has an adhesive strength to PEEK resin of 2.5 N/cm2 or more when cured, the composition can exhibit sufficient adhesive strength to PEEK resin. The curable epoxy composition for a rotatory electric machine preferably has a viscosity increase rate of 20000% or less before and after a storage test performed under conditions of a temperature of 23 + 5°C and a humidity of 50 + 5% for 41 days. Due to the above configuration, the curable epoxy composition has excellent long-term stability and handleability. The curable epoxy composition for a rotatory electric machine preferably has a glass transition temperature of 170°C or higher when cured. Due to the above configuration, the curable epoxy composition can easily exhibit sufficient heat resistance. The present disclosure also provides a cured product of the curable epoxy composition for a rotatory electric machine. The present disclosure also provides a stator for a rotatory electric machine, the stator including the cured product and the cured product being formed in a manner covering a stator coil. The present disclosure also provides a rotor for a rotatory electric machine, the rotor including the cured product, the cured product covering a winding of the rotor. Advantageous Effects of Invention According to the curable epoxy composition for a