JPS5915371B2 - Capacitor manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a capacitor which is covered with a plastic film by heat sealing.

In general, an aluminum case or a plastic molded case is often used as an envelope for capacitors, but recently, as the performance of plastic films has improved, a method has been proposed in which the capacitor element is directly wrapped in plastic film and heat-sealed.

In this case, plastic films have contradictory advantages and disadvantages in terms of folding durability, tear strength, moisture resistance, water resistance, gas permeability, oil resistance, heat sealability, etc., and a single plastic film can completely ensure the airtightness of the capacitor. It is extremely difficult to maintain.

Although polyethylene has low water absorption and moisture permeability and excellent heat sealability, it has a considerably high gas permeability.

Polyamide also has the disadvantage of low gas permeability but high moisture permeability.

Moisture has a significant effect on the characteristics of capacitors, so is it strictly necessary to understand the manufacturing process and product moisture absorption? 1 lJfl, so the high moisture permeability is a fatal flaw as an exterior material for a capacitor.

In addition, since the adhesion between the terminal and the plastic film is poor, the adhesion of the terminal lead-out portion is poor and the electrolyte escapes, resulting in a shortened capacitor life.

The present invention has been made in view of the above-mentioned circumstances, and includes pasting an ionomer resin film and at least one plastic film selected from polyamide, polypropylene, polyester, polyvinylidene fluoride, and polyvinylidene chloride on the top and bottom of a capacitor element, respectively. The combined laminate film is placed so that the ionomer resin film is on the inside, and the laminate film is heat-sealed to improve the adhesion between the ionomer resin film and the terminal and form an exterior, which makes it compact, airtight, and capable of mass production. It is an object of the present invention to provide a method for manufacturing capacitors that is easy to use and inexpensive.

An embodiment of the present invention will be described below with reference to the drawings.

A laminate film made by laminating two or more types of plastic films takes advantage of the strengths of each film and compensates for each other's weaknesses, making it ideal as a capacitor envelope material.

Furthermore, by coating aluminum foil with an ionomer resin, a laminate film with excellent mechanical strength and chemical resistance, low moisture permeability and gas permeability, and heat sealability can be obtained.

In order to wrap a capacitor element with such a laminate film and use it as an envelope, the inner film, that is, the film that comes into contact with the capacitor element, must have excellent chemical properties such as oil resistance, solvent resistance, and chemical resistance. Therefore, the outer film must have excellent physical properties such as mechanical strength, heat resistance, moisture resistance, gas permeability, and printability.

Therefore, as a result of various experiments, the present inventor created a laminate film that satisfies each of the above requirements using an ionomer resin film with a thickness of 1 to 1 oooμ as a base, and combined this with polyamide,
polypropylene, polyester, polyvinylidene fluoride,
At least one type of polyvinylidene chloride has a thickness of 1 to
It has been discovered that a capacitor with good characteristics can be obtained by wrapping and heat-sealing a 1000 μm plastic film with the ionomer resin film on the inside, that is, on the side that contacts the capacitor element.

Ionomer resin film consists of α-olefin chains and α,β
It is a product of unsaturated carboxylic acid cross-linked with metal ions, and the metal ions elute and bond with the metal, so it has good adhesion to the metal.
It has good adhesion with the terminals placed on the inside, that is, the side that contacts the capacitor element, and the terminal lead-out part is completely sealed.Ionomer resin film also has excellent oil, solvent, and chemical resistance, so it is suitable for capacitor elements. It is impregnated with a chemical reaction with the electrolyte, which can extend the life of the capacitor without causing corrosion.

To explain the present invention in more detail, as shown in FIG. 1, laminate films 3 are placed above and below a capacitor element 2 to which a terminal 1 is attached.

As shown in FIG. 2, the laminate film 3 has an ionomer resin film 4 on the side in contact with the capacitor element 2, and on the outside, at least one of polyamide, polypropylene, polyester, polyvinylidene fluoride, and polyvinylizo chloride 7(1). A kind of plastic film 5 is placed.

Then, the capacitor element 2 is loaded between two upper and lower laminate films 3 with the 4 sides of the inner ionomer resin films facing each other, and the capacitor element 2 is sealed by heat-sealing with a heating device 6 such as a hot plate or an indenter. It is then cooled to form the exterior.

The laminate film 3 may be laminated with a metal foil 7 such as aluminum or tin interposed between an inner ionomer resin film 4 and an outer plastic film 5, as shown in FIG. If an intervening material is used, the moisture permeability will be further reduced.

Alternatively, as shown in FIG. 4, at least one laminate film 3 may be thermoformed in advance into a shape capable of accommodating the capacitor element 2, and then heat-sealed.

Furthermore, as shown in FIGS. 5 and 6, a laminate film 3 may be wound around the outer periphery of the capacitor element 2, and one side and the end surfaces thereof may be heat-sealed.

In the present invention, the heat sealing of the laminate film 3 of the ionomer resin film 4 and the plastic film 5 is performed by hot plate welding (temperature 120 to 180°C, time 2 to 7 seconds) or impulse welding (temperature 120 to 180°C, time 2 to 7 seconds).
8 seconds), ultrasonic welding (frequency 15-30KHz, load 1
0 to 20 cycles/ctrl, time 1 to 10 seconds) or high frequency welding (frequency 10 to 70 MHz, load 2 to 15 kg/
(C time: 1 to 7 seconds) Any method may be used.

If the laminate film 3 is subjected to secondary processing such as electron beam irradiation, corona discharge treatment, and biaxial stretching before lamination, mechanical and thermal properties can be improved and heat sealing can be performed efficiently. .

The ionomer resin film 4 and the plastic film 5 can be laminated by heating and fusing the two films or pasting them together with an adhesive, or by dropping a heated and melted material onto one side of one film in the form of a shower set or a strip. They are integrated by passing them through rolling rollers or stretching rollers, or by applying heated and molten material to one side of one film using a roller.

Next, Table 1 shows an example of comparison between the embodiment of the present invention and a conventional reference example.

As is clear from Table 1, all of the examples of the present invention have a smaller capacitance change rate after the humidity test than the conventional reference examples, and have excellent sealing performance with less deterioration of characteristics due to moisture absorption of the exterior. I understand.

As detailed above, according to the present invention, an ionomer resin film and a polyamide film are formed on the upper and lower sides of the capacitor element, respectively.
polypropylene, polyester, polyvinylidene fluoride,
A laminated film with at least one kind of plastic film of polyvinylidene chloride is arranged with the ionomer resin film on the inside and heat sealed to improve the adhesion between the ionomer resin film and the terminal to form an exterior. Accordingly, it is possible to provide a method for manufacturing a capacitor that is small, has good airtightness, is easy to mass-produce, and is inexpensive.

[Brief explanation of the drawing]

The drawings are for explaining the method of manufacturing a capacitor according to the present invention. Figure 1 is a perspective view showing the heat sealing method, and Figure 2 shows an example of a capacitor heat sealed by the method shown in Figure 1. 3 is a sectional view showing a capacitor according to another embodiment, FIG. 4 is a perspective view showing a heat sealing method according to another embodiment, and FIG. 5 is a sectional view showing a heat sealing method according to another embodiment. FIG. 6 is a perspective view showing a capacitor heat-sealed by the method shown in FIG. 5. 1...Merchandise, 2...Capacitor element, 3
... Laminate film, 4 ... Ionomer resin film, 5 ... 7 plastic film, 6 ... Heating device, I ... Image metal foil .

Claims (1)

[Scope of Claims] 1. A laminate film of an ionomer resin film and at least one plastic film selected from polyamide, polypropylene, polyester, polyvinylidene fluoride, and polyvinylidene chloride is placed on the top and bottom of the capacitor element, respectively, with the ionomer resin film on the inside. A method for manufacturing a capacitor, characterized in that the capacitor is arranged in such a manner that the capacitor is heat-sealed to form an exterior. 2. The method of manufacturing a capacitor according to claim 1, wherein the laminate film is previously thermoformed into a shape capable of accommodating a capacitor element, and then heat-sealed to form the exterior. 3. The method of manufacturing a capacitor according to claim 1, wherein the laminate film is wound around the outer periphery of the capacitor element and heat-sealed to form the exterior.