JPH097444A - Layered insulator - Google Patents

Abstract

PURPOSE: To provide a layered insulator whose hygroscopicity is eliminated and inside which a fine crack is not caused and which is excellent in insulating performance. CONSTITUTION: Nonwoven fabric 1 of polyester fiber such as PET fiber whose surface wettability is improved by surface reforming processing such as corona discharge treatment, is wound round core metal 3, and is hardened after thermosetting resin such as epoxy resin is impregnated. Since the nonwoven fabric 1 of polyester fiber is used as a base material, hygroscopicity is eliminated, and since wettability is improved by surface reforming treatment, it completely adheres to epoxy resin or the like, and a fine crack is not caused.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated insulator arranged around a central conductor such as a bushing.

[0002]

2. Description of the Related Art As a laminated insulator as described above, a kraft insulating paper as a base material is wrapped around a mandrel together with an aluminum foil for an electrode, and a thermosetting resin such as an epoxy resin is impregnated and cured. Have been widely used. However, since the kraft insulating paper has some hygroscopicity, such a conventional laminated insulator may have a reduced insulating property due to the infiltration of moisture under special use conditions.

Therefore, the inventor of the present invention is developing a laminated insulator using a nonwoven fabric of polyester fiber such as PET fiber (polyethylene terephthalate resin fiber), which is much less hygroscopic than kraft insulating paper, as a base material. A part of the technology relating to this has already been applied for as a patent such as JP-A-4-255617.

However, in the laminated insulator thus manufactured, the aluminum foil wound as an electrode therein is completely bonded to the thermosetting resin.
There were cases where minute cracks were generated inside. Such minute cracks may cause internal discharge and reduce the insulation.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and provides a laminated insulator having no hygroscopicity and excellent in insulating property without causing microcracks inside. It was done by.

[0006]

Means for Solving the Problems As a result of pursuing the cause of microcracks in a prototype of a laminated insulator using a nonwoven fabric of polyester fiber such as PET as a base material, the inventors have found that It was determined that minute cracks may be observed at a slightly distant position, and the cause thereof is poor wettability between the nonwoven fabric of polyester fiber such as PET and the thermosetting resin such as epoxy resin.

The present invention has been completed on the basis of the above findings, in which a nonwoven fabric made of polyester fiber having surface wettability improved by surface modification treatment is wound and impregnated with a thermosetting resin. It is characterized by. As the surface modification treatment, for example, corona discharge treatment can be adopted. Further, it is preferable that the non-woven fabric of polyester fiber is a non-woven fabric of PET fiber and the thermosetting resin is an epoxy resin.

[0008]

The laminated insulator of the present invention is formed by winding a non-hygroscopic polyester fiber non-woven fabric as a base material and impregnating it with a thermosetting resin. Hygroscopicity is lower than that of an insulator, and there is no risk of deterioration of insulation due to ingress of water. Moreover, since the surface of the non-woven fabric of polyester fiber is subjected to the surface modification treatment to improve the wettability, the thermosetting resin and the non-woven fabric of polyester fiber are completely adhered to each other, and there is no possibility of generation of microcracks. Therefore, it is possible to obtain a laminated insulator having an excellent insulating property. In addition to corona discharge treatment, various methods such as silane treatment, ozone treatment, and electron beam treatment can be adopted as the surface modification treatment.

[0009]

The present invention will be described below in more detail with reference to the illustrated embodiments. FIG. 1 is a perspective view conceptually showing a manufacturing process of a laminated insulator of the present invention. In this figure, 1 is a nonwoven fabric of polyester fiber, 2 is an aluminum foil, and 3 is a core. In the embodiment, PE is used as the nonwoven fabric 1 of polyester fiber.
A non-woven fabric of T fiber (polyethylene terephthalate resin fiber) is used. As shown in FIG. 1, a polyester fiber nonwoven fabric 1 is an aluminum foil 2 that constitutes a capacitor electrode.
It is the same as in the prior art in that it is wound around the mandrel 3 in multiple layers and then impregnated with a thermosetting resin such as an epoxy resin to be cured.

However, in this embodiment, as shown in the cross section of FIG. 2, the surface of the nonwoven fabric 1 made of polyester fiber is a discharge-treated surface 4 which has been surface-modified in advance to improve its wettability. The corona discharge treatment adopted as the surface modification treatment in the examples is a method of chemically and physically modifying the surface of the object to be treated by high-voltage, high-frequency corona discharge irradiation. Processing is performed by passing the object to be processed through.

When this surface modification treatment by corona discharge is performed, molecules on the surface of the nonwoven fabric 1 of polyester fiber are polarized to generate polarity and improve wettability, so that complete adhesion without cracks with the epoxy resin. Will be done.
Moreover, in the corona discharge treatment, it is sufficient to dispose the electrode facing the treatment roll and pass the non-woven fabric 1 between them, so that the manufacturing equipment can be simplified as compared with the case of the silane treatment, and in terms of occupational health and pollution. There are no problems and advantages.

The preferable output of the corona discharge device varies depending on the passing speed between the electrodes of the nonwoven fabric 1. However, when the passing speed is 6 m / min, the output of the corona discharge device is 0.5.
It is preferably in the range of ˜3 kilowatts. This is because if the output is smaller than 0.5 kW, a sufficient surface modification effect cannot be obtained, and if it exceeds 3 kW, carbonization of the polyester fiber occurs. If the low temperature heat treatment of the nonwoven fabric 1 is performed after the corona discharge treatment, the wettability improved by the corona discharge treatment may be deteriorated. Therefore, it is preferable to perform the corona discharge treatment on the nonwoven fabric 1 that has been previously subjected to the low temperature heat treatment.

The polyester fiber non-woven fabric 1 having improved wettability by the corona discharge treatment in this manner is wound around the mandrel 3 in multiple layers together with the aluminum foil 2 which constitutes the capacitor electrode, and then the epoxy resin. A thermosetting resin such as the above is impregnated and cured to form a laminated insulator. This laminated insulator is a non-woven fabric of polyester fiber that has no hygroscopicity 1
Since this is a base material, there is no possibility that the insulative property will be deteriorated by the intrusion of water. Moreover, since the polyester fiber and the epoxy resin and the like are well wetted and complete adhesion is achieved, no microcracks are generated.

In order to confirm the effect of the present invention, eight prototypes of polyester fiber nonwoven fabric 1 subjected to corona discharge treatment and eight comparative products not subjected to surface modification treatment were manufactured and disassembled. When the state of generation of internal microcracks was confirmed, microcracks were found in 4 out of 8 of the comparative product, but none of the prototypes of the present invention found microcracks in 8 of them. .

[0015]

As described above, since the laminated insulator of the present invention has no hygroscopicity and does not generate minute cracks inside, it is highly valuable as a laminated insulator having extremely excellent insulating properties. It is a thing.

[Brief description of drawings]

FIG. 1 is a perspective view conceptually showing a manufacturing process of a laminated insulator of the present invention.

FIG. 2 is a cross-sectional view of a surface-modified polyester fiber nonwoven fabric.

[Explanation of symbols]

1 Non-woven fabric of polyester fiber, 2 Aluminum foil, 3 cores, 4 Discharge treated surface

Claims (3)

[Claims] 1. A laminated insulator characterized in that a nonwoven fabric of polyester fiber having a surface wettability improved by a surface modification treatment is wound and impregnated with a thermosetting resin. 2. The laminated insulator according to claim 1, wherein a corona discharge treatment is adopted as the surface modification treatment. 3. The laminated insulator according to claim 1, wherein the polyester fiber nonwoven fabric is a PET fiber (polyethylene terephthalate resin fiber) nonwoven fabric, and the thermosetting resin is an epoxy resin.