JPS6351533B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a metallized plastic film, particularly a metallized plastic film suitable for use in wound capacitors. The present inventors recently discovered that a metal evaporated film is formed on one side of a support substrate made of a plastic film having a smooth surface by an appropriate evaporation method, while one or both sides of another plastic film is subjected to electrical corona discharge treatment. The metal vapor deposited film and the corona discharge treated surface are then bonded by applying heat and pressure without intervening an adhesive so that the metal vapor deposited film and the corona discharge treated surface come into contact with each other. We have developed a novel method for producing a metallized plastic film, which is characterized in that the supporting base material is peeled off from the bonded material and the metal vapor-deposited film is transferred. When the metallized plastic film obtained by this method is used in the manufacture of capacitors, it has high voltage resistance, which cannot be achieved with metallized plastic films manufactured by conventional transfer methods using adhesives. It was found that a compact capacitor can be obtained. However, there are problems in directly using the metallized plastic film produced in this way in the manufacture of capacitors, and further improvements are needed. Generally, in the case of a metallized plastic film capacitor obtained by winding a metallized plastic film, an unmetallized portion is provided at one end of the vapor-deposited metal film surface of the metallized plastic film used, and a two-layer metallized plastic film is formed. A capacitor element is obtained by winding the film so that the unmetallized portions thereof face each other. Further, after spraying molten metal onto both end faces of this capacitor element, lead wires are attached to obtain a metallized plastic film capacitor. In this case, the unmetallized portion is provided to ensure insulation between opposing electrodes, and is essential in metallized plastic films for capacitors. Therefore, even in a metallized plastic film obtained by a transfer method using an electric corona discharge treatment as described above without using an adhesive, the unmetallized portion as described above must be removed when used for a capacitor. This makes it advantageous as a metallized plastic film for capacitors. The method of providing an unmetallized part, which is conventionally known as a means of obtaining a metallized plastic film by direct vapor deposition, is that when metal is vapor-deposited onto a base material, the unmetallized part is preliminarily covered with tape, oil, etc. The process consists of masking and then metal vapor deposition. By using a metal film-supporting substrate having an unmetallized portion obtained by such a conventional technique, as a result, a metallized plastic film having a similar unmetallized portion can be obtained by the method of the present invention. Of course it is also possible. However, this conventional method requires a long time to replace the tape, oil, etc., and is not necessarily a satisfactory method. In view of this situation, the present inventors have completed various attempts to develop a method for providing unmetallized portions to a metallized plastic film simply and in a short time, and as a result have completed the present invention. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for manufacturing a metallized plastic film suitable for use in capacitors. Another object of the invention is to provide a simple and quick method for providing unmetallized areas on a metallized plastic film. A further object of the present invention is to provide a capacitor constructed from a metallized plastic film as described above, which has high withstand voltage characteristics and a long service life. These and other objects and features of the invention will become apparent from the following description. That is, the present invention forms a metal vapor deposited film on one side of a plastic film having a smooth surface as a metal film supporting base material, and activates one or both sides of the other plastic film by electrical corona discharge treatment. The two thus obtained are adhered by applying heat and pressure without using an adhesive so that the vapor deposited film and the activated film surface come into contact with each other, and then the supporting base material is peeled from the thus obtained adhesive. In a method for manufacturing a metallized plastic film including a step of transferring a vapor-deposited metal film, when adhering the vapor-deposited metal film and the activation film surface, a pressure difference is applied to the bonded portion between the two,
The present invention relates to a method for manufacturing a metallized plastic film, characterized in that a part of the vapor-deposited metal film is not transferred onto the activated film to form a non-metal transfer portion. Thus, according to the present invention, it is possible to easily and quickly
In other words, there is no need for masking treatment with tape, oil, etc., or removal operations of these.
Metallized plastic films suitable for capacitor manufacturing can be produced. In the method of the present invention, a metal vapor deposition film is first formed on a supporting substrate, and this can be done using a conventionally known vapor deposition method. , copper, chromium, nickel, etc. can be used. Also,
Polypropylene, polyethylene, etc. can be used as the supporting base material. Corona discharge treatment can also be carried out according to known techniques, and the dielectric substrate to be corona discharge treated can be any plastic film or sheet that can be activated by this treatment. In particular, films or sheets of non-polar polymeric materials such as polyethylene and polypropylene,
Alternatively, films or sheets of polar polymeric materials such as polyethylene terephthalate and polyvinylidene fluoride are advantageous. The metal vapor deposited film formed as described above and the treated surface of the dielectric substrate subjected to corona discharge treatment are treated by applying heat and pressure using a press roll or a press plate, etc., to interpose an adhesive. The adhesive is bonded with a predetermined bonding strength and a uniform bonding surface. Here, when adhering the two, the temperature condition and the pressure condition are in an inversely proportional relationship. That is, higher pressure is required at lower temperatures to achieve the same adhesive strength, whereas lower pressure is required at higher temperatures.
Therefore, these are appropriately selected depending on the predetermined adhesive strength. After adhesion, the carrier substrate can be immediately peeled off. In the method of the present invention, when bonding the vapor-deposited metal film and the activated film surface, the following can be exemplified as a specific embodiment for applying a pressure difference to the bonded portion between the two. (a) Forming grooves of a predetermined shape on the surface of the pressure roll; (b) Applying wind pressure between the vapor-deposited metal surface and the activated film surface in the groove portion. An example of the manufacturing method will be described below with reference to the accompanying drawings. As shown in FIG. 1, a plastic film A as a base material is subjected to an electrical corona discharge treatment C. Next, the metal surface of the metallized film B, in which a vapor-deposited metal film is uniformly formed over the entire surface by a vapor deposition method on one surface of a supporting base material of a plastic film having a smooth surface, and the corona-treated surface of the plastic film A, which has been subjected to the corona treatment. are joined by press roll D.
In this case, the press rolls are shown in Figures 2 and 3.
As shown in the figure, grooves with the same pattern as the unmetallic part required to obtain the pressure difference of the press are provided on its surface. When two types of films are joined,
Since this groove part is almost not pressurized, only the groove part cannot satisfy the adhesion conditions between the metal surface and the corona-treated plastic film surface, resulting in peeling.
After that, a metal film surface along the shape of the groove remains as an untransferred part on the supporting substrate, and a pattern of the required non-metal film part is left on the surface of the plastic film of the substrate as an untransferred part. can get. This method is also characterized in that even complex patterns on non-metallic film parts can be easily and continuously obtained by drawing the required pattern on the press roll with grooves. In addition, in order to obtain strong adhesive strength between the vapor-deposited metal surface of the supporting substrate and the corona-treated plastic film surface of the substrate, strong electrical corona treatment is applied to the plastic film surface of the substrate, and When bonding the base material and the base material, it may be done under strong pressure or high temperature conditions. Under such conditions, the adhesion condition may be satisfied simply by the supporting substrate and the substrate being in close contact even in the pressure-free portion of the groove. When joining under such conditions, as shown in Figure 4, by applying wind pressure F between the metal surface of the supporting base material in the groove portion and the corona-treated surface of the plastic film of the base material, the metal surface is Since the corona-treated surface of the plastic film and the corona-treated surface of the plastic film are no longer in close contact with each other and the adhesion conditions are no longer satisfied, the required non-metallic film portion can be obtained on the metal film transfer surface of the plastic film as the base material. The present invention will be explained in more detail below. Example 1 A polypropylene film with a thickness of 10 μm was used, and its surface was subjected to corona discharge treatment with an intensity of 1.5 W・s/
cm ² and the surface of an aluminum metal film deposited in accordance with a conventional method on a 20 μm thick polypropylene film as a supporting substrate without corona discharge treatment. It was adhered using the grooved roll shown in the figure. The roll temperature at this time is 100
℃, and the lamination pressure was 18 kg/cm. Thereafter, a transfer experiment was performed by peeling it off. As a result, a metallized polypropylene film was obtained in which an untransferred portion having the same width as the groove was transferred in a linear form. Example 2 A transfer experiment was conducted using a polyethylene terephthalate film having a thickness of 5 μm and using the same grooved roll as in Example 1. A 20 μm thick polypropylene film that was not subjected to corona treatment was used as a support substrate. The corona treatment strength was 0.5 W·s/cm ² , the temperature of the laminating roll was 120° C., and the pressure was 18 Kg/cm. As a result, a metallized polyethylene terephthalate film was obtained in which the untransferred portions having the same width as the grooves were transferred in a linear form. Example 3 A polypropylene film with a thickness of 10 μm was used, and its surface was corona treated with an intensity of 1.5 W・s/cm ²
The surface on which electrical corona discharge was applied and the surface of an aluminum metal film deposited in accordance with a conventional method on a 20 μm thick polypropylene film as a supporting base material without corona discharge treatment were as shown in FIG. 3 of the present invention. It was attached using a patterned roll. The roll temperature at this time is 100
℃, and the lamination pressure was 48 kg/cm. Thereafter, a transfer experiment was performed by peeling it off. As a result, a vapor-deposited metal film having the same pattern as the convex portions of the patterned roll was transferred to the corona discharge treated polypropylene film. Example 4 Using a polypropylene film with a thickness of 10 μm, the surface was subjected to electrical corona discharge at a corona treatment intensity of 2.0 W・s/cm ² and the thickness of the supporting base material that was not subjected to corona discharge treatment. A 20 μm polypropylene film was bonded to the surface of an aluminum metal film deposited in accordance with a conventional method using a roll shown in FIG. 2 of the present invention. At that time, the adhesive was bonded while blowing air into the grooves of the grooved roll as shown in FIG. The air pressure was varied from 0 to 3.0 kg/cm ² as shown in Table 1. At this time, the roll temperature was 120°C and the lamination pressure was 18 kg/cm. Thereafter, a transfer experiment was performed by peeling it off. The experimental results are shown in Table 1. In the metallized polypropylene films No. 2, 3, and 4 transferred under the above conditions, untransferred portions having the same width as the grooves were obtained in the form of a line.

[Table] ×……Bad
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[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing an example of the method of the present invention, and FIGS. 2 and 3 are enlarged views of the press roll portion in FIG. FIG. 4 is a schematic diagram showing a press roll section of another embodiment of the method of the present invention.

Claims (1)

[Claims] 1 (i) A metal vapor deposited film is formed on one side of a plastic film having a smooth surface as a supporting base material, and (ii) one or both sides of the other plastic film is subjected to electric corona discharge. (iii) bonding both steps (i) and (ii) by applying heat and pressure such that the deposited metal film and the activated film surface are in contact with each other; (iv) ) Next, in the method for manufacturing a metallized plastic film, which includes the step of peeling off the supporting base material from the obtained adhesive and transferring the vapor-deposited metal film, when adhering the vapor-deposited metal film and the activated film surface, The above-mentioned method is characterized in that by applying a pressure difference to the joint portion between the two, a part of the vapor-deposited metal film is not transferred onto the surface of the activated film, and a non-transferred portion of the metal is formed. A method for producing a chemically modified plastic film. 2. The method according to claim 1, characterized in that the pressure difference is provided by forming grooves of a predetermined shape on the surface of the pressure roll. 3. The method according to claim 2, further comprising applying wind pressure between the vapor deposited film and the activated film surface in the groove portion.