JPH0252420B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dielectric material and a protective material for a plastic film capacitor or an insulating paper capacitor (hereinafter collectively referred to as a film capacitor). It improves the adhesion between the dielectric and the electrode, prevents short circuits of the capacitor, worsens the dielectric loss tangent, and prevents a decrease in insulation resistance, resulting in less variation in capacitance, higher performance, and improved workability compared to conventional capacitors. The aim is to prevent this from deteriorating.

Film capacitors that use plastic film, metalized plastic film, insulating paper, or metalized insulating paper (hereinafter collectively referred to as film) are formed by forming wound or laminated elements by heating and applying pressure. In capacitors using conventional films, even after molding, the adhesion between dielectrics, between protective films, and between dielectrics and electrodes was incomplete.

If the adhesion is incomplete, the following disadvantages may occur.

(1) In the metallicon process using metal spraying, metallicon particles enter the film gap and short circuit the capacitor.

(2) In the metallicon process, the device is masked to prevent metallicon particles from flowing down the sides of the device, but when this masking is removed after metallicon, the protective film peels off, which affects workability and appearance in the subsequent process. The above problem arises.

(3) If the adhesion between the films is incomplete and the impregnation is not uniform, moisture will easily penetrate and the moisture resistance will be poor.

The present invention solves the above-mentioned conventional problems, and uses an adhesive layer (for example, polyalkylene terephthalate) that is non-adhesive at room temperature and sticky at temperatures above 60°C as a dielectric film or protective film. It is a modified ether type polyester resin whose main component is Vylon 300 and Vylon 500 manufactured by Toyobo Co., Ltd.)
This method uses films coated with , and the heat during thermoforming brings the films into close contact with each other or the film and the electrode. Note that if an adhesive layer that is sticky even at room temperature is used, workability and yield will be significantly reduced in the film winding process and other processes prior to thermoforming.

Different adhesives were prepared with adhesive temperatures ranging from 20 to 100°C, and each was applied to a polypropylene film to form an adhesive layer. Film capacitors were prepared by winding these films with a winder, and their workability was compared and studied under the same conditions as when a normal polypropylene film without an adhesive layer was used. The workability at this time was evaluated based on the degree of occurrence of disordered winding due to meandering of the film. The results are shown in FIG. As is clear from this, when using an adhesive whose tackiness temperature is 60°C or higher, the same results as when using a polypropylene film without an adhesive layer applied were obtained.

This is presumed to be due to the following reason. In other words, when a film coated with an adhesive layer is rolled,
As the coefficient of friction with the winder roller increases,
The frictional heat between the roller and the film increases compared to the conventional method. At this time, in the case of a film coated with an adhesive having a low tackiness temperature, the adhesive adheres to the roller, resulting in disordered winding of the film, which reduces the workability of manufacturing the film capacitor.

When winding a conventional polypropylene film without an adhesive layer applied at room temperature, the film temperature was below 35 to 40°C; When the film is wound under the same conditions, the frictional heat with the roller increases, and the temperature of the film reaches approximately 60°C.
This is because the temperature rises to ℃. In Fig. 1, A indicates the 100% workability line when using conventional film.

FIG. 2 shows an embodiment of the present invention, in which the adhesive layer 3 of the present invention, which is non-adhesive at room temperature and tacky at 60°C, is applied to the surface of the outer protective film 2 for the element 1 of a wound capacitor. FIG. 3 is a diagram showing a case where a film coated with

FIG. 3 is a diagram showing the peeled state of the film after removing the masking in the metallicon process, where 1 indicates the element and 3 indicates the adhesive layer which is non-tacky at room temperature and tacky at 60°C.

As described above, if the film of the present invention whose surface is coated with an adhesive layer that is non-tacky at room temperature and tacky at 60°C or higher is used as a protective film, peeling of the film can be greatly reduced and workability in post-processing can be improved. And it has come to greatly contribute to the yield in terms of appearance. In other words, the incidence of protective film peeling is 5.8% when using conventional film.
On the other hand, when using the film coated with the adhesive layer of the present invention on the surface, it was reduced to 0.02%. If used by coating a protective film and a dielectric film, it is possible to prevent short circuits and deterioration of the dielectric loss tangent (T _AN Δ) of the capacitor due to penetration of metallicon particles into gaps between the films. Product and B indicate the conventional product. In addition, it has become possible to prevent the insulation resistance (IR) from decreasing due to the intrusion of the exterior resin. In FIG. 4b, A shows a product of the present invention, and B shows a conventional product. With the structure of the present invention, the adhesive layer, which is non-tacky at room temperature and sticky at 60°C or higher, replaces the impregnating agent, allowing uniform molding with few air gaps, thereby reducing capacitance. Corona starting voltage (4th
(see figure c) and short-time breakdown voltage (see figure 4 d)
We were able to provide a capacitor with high moisture resistance and excellent moisture resistance.

[Brief explanation of drawings]

Figure 1 shows the temperature at which the adhesive layer becomes sticky, and
Figure 2 shows the relationship between workability and workability in processes before the thermoforming process.
The above is a perspective view showing the winding state when the film coated with the adhesive layer on the surface is used as a protective film for a wound type capacitor. Figure 4 is a perspective view showing the state in which the protective film has been peeled off, and Figure 4 is a diagram comparing the primary characteristics of the capacitor with the present invention product A and the conventional product B, where a is the dielectric loss tangent (T _AN Δ) and b is the insulation value. It is a diagram showing the resistance (IR), c is the corona onset voltage, and d is the short-time breakdown voltage. 1... Element, 2... Protective film, 3... Adhesive layer.

Claims (1)

[Claims] 1 Plastic whose surface is coated with an adhesive layer that is non-adhesive at room temperature and sticky at 60°C or higher for the purpose of adhesion between dielectric materials or protective materials and adhesion between dielectric materials and electrodes in capacitors. A capacitor characterized by using a film, a metalized plastic film, an insulating paper, or a metalized insulating paper.