JPH07335483A - Manufacture of film capacitor film - Google Patents

Abstract

PURPOSE:To reduce the amount of static electricity on a surface modified film by a method wherein surface modified layers using a paint containing a high- molecular material as their main component are respectively formed on both surfaces of a PET film to form the surface modified film and the surface is subjected to discharge treatment while the film is made to travel. CONSTITUTION:Surface modified layers containing a polyurethane resin as their main component are respectively provided on both surfaces of the surface and rear of a PET film formed of a polyethylene terephthalate (a PET). A surface modified PET film 7 formed using these surface modified layers is wound off from a winding-off part 6, is put in a treating chamber 14, is turned into a surface modified PET film 11 reduced its amount of static electricity by a plasma treatment in the chamber 14 and the film 11 is wound on a winding part 12. A discharge treatment of the surface of the film 7 is performed as a plasma treatment in a reduced pressure or a high-frequency corona treatment in the atmosphere. Thereby, the amount of static electricity on the film 11 is reduced and the workability of a winding for manufacturing a film capacitor element can be remarkedly improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film made of a polymer material used for film capacitors.

[0002]

2. Description of the Related Art In recent years, along with the development of electrical technology, electronic circuits have been remarkably applied and used widely in various fields such as cameras, machine tools and automobiles, as well as so-called electrical equipment. Many parts used in these electric and electronic circuits are required to have a wide range of requirements such as reliability, safety, and price in addition to performance. In particular,
High reliability is required for electronic components forming electronic circuits used in a wide range.

For this reason, materials conventionally used,
Under the manufacturing conditions, the requirement for reliability cannot be satisfied, and it has become necessary to improve the materials and the manufacturing conditions.

Conventionally, techniques for improving the reliability of film capacitors include lowering the voltage applied to the film per unit thickness (reducing the potential gradient), selecting the outer resin material, and the outer packaging method. Have been improved.

Further, in recent years, along with the miniaturization of electronic parts, there has been a strong demand for miniaturization of film capacitors, and manufacturers of film capacitors have made various developments in order to meet these demands. . In particular, the film has been improved as a method for reducing the size and improving the reliability. In the improvement of the film, in addition to making the film material a new material, a surface-modified film has been developed which forms an extremely thin heterogeneous material layer on the surface of a conventionally used film material.

[0006]

A film capacitor using this surface-modified film, particularly a metallized film capacitor in which a metal thin film layer is formed on the surface of the film by a vacuum deposition method or the like, has a constant temperature and constant humidity ( For example, in the test of the capacitor characteristics in a long-term use at 60 ° C. and 95%), a better reliability than the conventionally used film was obtained.

Generally, the manufacturing method of a film capacitor is
Mainly used are a method in which a metallized film cut into a predetermined width and a laminated film are superposed and wound, and a manufacturing method in which the metallized film and the laminated film are alternately laminated and then slit. If you try to manufacture the surface-modified film by winding the metallized film and the laminated film, wrinkles will occur on the winding machine that has been used conventionally, or the metallized film and the laminated film will be wound at the same time. When cutting only and winding the laminated film around the outer circumference, the metallized film may shift laterally as the laminated film runs or the metallicized film may run at the same time as the laminated film runs depending on the contact state between the laminated film and the laminated film. There are problems such as being lost.

[0008] As a result of investigating and analyzing trouble phenomena when these surface-modified films are used, a surface-modified film in which a surface-modified layer mainly containing urethane resin is formed on the surface of the film is compared with a normal film. It was found that the charge amount was large.

An object of the present invention is to reduce the charge amount of a surface modified film.

[0010]

In order to achieve this object, the present invention mainly comprises a polymer material having a urethane bond and / or an ester bond, or both, on the surface of a film made of the polymer material. A surface modified layer is formed by a paint to form a surface modified film, and the surface of the film is subjected to electric discharge treatment while the surface modified film is running.

[0011]

The action of winding the film-type film capacitor, which can solve the problem at the time of winding the film by reducing the charge amount and has been used for the conventional film having no surface modification layer, is provided. You can use it.

That is, since a surface-modified film having a low charge amount and a high surface tension can be used, 1. The slipperiness between the films or between the metallized films is improved and the conventionally used winding machine can be used.

2. Highly reliable film capacitors can be produced with high yield. Etc. are possible.

[0014]

EXAMPLE An example of the present invention will be described below.

In this example, an example in which polyethylene terephthalate (hereinafter referred to as PET) is used as the polymer material will be described.

FIG. 1A shows a sectional view of a conventional PET film. A film formed entirely of PET. FIG. 1 (b) shows the surface modified P used in the present invention.
A sectional view of an ET film is shown. P formed from PET
The ET film 1 is provided with a surface modification layer 2 containing a polyurethane resin as a main component on both the front and back surfaces.
The film 1 has a thickness of 2 to 20 (μm), and the surface modification layer has a thickness of about 0.01 to 1 (μm).

FIG. 2 shows an example of a plasma treatment method for a surface-modified PET film in vacuum. The inside of the vacuum layer 3 is evacuated to the level of 10 ^-2 (Pa) by an unillustrated vacuum pump by an exhaust pipe 5 connected to the vacuum valve 4. Inside the vacuum layer 3 is a processing chamber 14 for generating a plasma to process the film. In the processing chamber 14, magnetron type discharge electrodes 8 are arranged so as to be on the front and back of the film, and an alternating voltage 10 is applied to these electrodes by alternately wiring. To generate the plasma 9, an atmospheric gas is introduced through the gas introduction pipe 13 so that the discharge electrode 8 can easily discharge. In this embodiment, when introducing oxygen gas, 0.5 (l) per minute is supplied, and when introducing argon gas, 0.2 (l) is supplied per minute to cause discharge at the discharge electrode 8 to generate plasma 9. Let The power supplied to the discharge electrode was 60 (Hz) and 800 (w). Surface modified PET
The film 7 is unwound from the unwinding unit 6 and enters the processing chamber 14. In the processing chamber 14, the surface-modified PET film 7 becomes the surface-modified PET film 11 whose amount of charge has been reduced by the plasma treatment and is wound around the winding section 12. At this time, the traveling speed between the unwinding section 6 and the winding section 12 is 100 (m / m).
in).

FIG. 3 shows the corona discharge treatment in the atmosphere.
The unwinding part 15 rotates in the A direction. 100 (m / mi
n) the surface-modified PET discharged from the unwinding portion 15 at the traveling speed
The surface of the film 16 is corona-treated on the first corona surface-treatment roll 21. The corona surface treatment roll 21 is made by adhering a high-resistance material having a uniform dielectric constant and thickness to the outer circumference of the iron roll, and the iron roll is connected to the ground 19. In addition, the corona surface treatment roll 21 has 2
There is a fixed electrode 20 with a gap 17 of (mm), and the frequency is 20 (KHz) between the fixed electrode 20 and the ground 19.
With a power output of 500 (W), a voltage is automatically adjusted to generate corona, and a high frequency voltage is applied to generate corona in the gap 17 provided between the corona surface treatment roll 21 and the fixed electrode 20. Let This method has a structure of electrodes, resistors (gaps), capacitors (dielectrics), and electrodes in an electrically equivalent circuit, and is devised so that corona generation in the width direction of the film is uniformly distributed. At this time, the surface-modified PET film 16 is on the outer periphery of the corona surface treatment roll 21
The vehicle is traveling at a traveling speed of 0 (m / min). Therefore, the surface modification P due to the corona generated in the gap 17
The surface of the ET film 16 was surface-treated.

The next corona surface treatment roll 22 has the same structure as the corona surface treatment roll 21. In the corona surface treatment roll 22, the surface-modified PET film 16 was passed through the lower portion of the corona surface-treatment roll 22 to perform the surface treatment with the corona on the back surface of the surface-modified PET film 16. Corona is generated by providing a 2 (mm) gap 24 between the fixed electrodes 24 provided under the corona surface treatment roll 22 and applying a high-frequency voltage between the earth 18 and the fixed electrode 23 by the high-frequency power source 25. Raised. Surface-modified PE with front and back surface treated with corona
The T film 27 passes through the guide roll 26, rotates in the B direction, and is wound around the winding portion 28.

In this example, the front and back surfaces of the surface-modified PET film were corona-treated, but the corona treatment on only one surface also satisfied the scope of the present invention.

[0021]

[Table 1]

As shown in (Table 1), the surface potential of a surface-modified PET film obtained by subjecting an untreated surface-modified PET film to oxygen plasma treatment in vacuum or high-frequency corona treatment in the atmosphere is the surface treatment effect. Was falling at. Regarding the surface tension, both the surface treated with oxygen plasma in vacuum and the surface treated with high frequency corona in the atmosphere had high surface tension. From these results, it is possible to reduce the amount of charge of the surface-modified PET film and increase the surface tension of the treated surface by subjecting the surface-modified PET film to oxygen plasma treatment in vacuum or high-frequency corona treatment in air. ,
It was found that the surface-modified PET film was surface-treated.

The conditions of oxygen plasma in vacuum shown in (Table 1) are 60 (Hz) and 800 (W) to the discharge electrode while supplying oxygen to the vacuum layer so as to be 10 ^-1 (Pa). AC power was supplied. Further, the corona treatment in the atmosphere is performed at a frequency of 20 using the corona treatment device described in the detailed description.
AC power with an output of 500 (W) at (KHz) was supplied.

4 and 5 show an example of a film capacitor winding machine. In FIG. 4, the unrolled portion 29 of the metallized film 30 formed with aluminum thin films having a predetermined margin on both the front and back sides, which is slit to the width 21 (mm), and the slit to the width 20 (mm) The metallized film 30 is a guide roller 31, 32, 3 with a winding machine provided with an unwinding portion 36 for the film 37.
After passing through 3, 34, 35 and 40, the first winding shaft 42 having a split shaft structure is reached.

On the other hand, the laminated film 37 reaches the first winding shaft 42 through the guide rollers 38, 39, 34, 35 and 40. As shown in the figure, the metallized film 30 and the laminated film 37 are brought into close contact with each other in a parallel state by the guide roller 34, and the two metallized film 30 and the laminated film 37 are simultaneously wound by the first winding shaft 42 via the guide rollers 35 and 40. To be When winding the metallized film 30 and the laminated film 37, the first winding shaft 42 and the second winding shaft 4 having a split shaft structure are wound.
The film between 1 has been cut. First winding shaft 4
After winding a predetermined film length in 2, the first winding shaft 42 and the second winding shaft 41 are reversed in the rotation direction C direction.

FIG. 5 shows the state after the inversion in FIG. Metallized film 30 and laminated film 37 in the inverted state
Is set so as to pass through the central portion of the split shaft of the second winding shaft 41. In this state, the first winding shaft 42 and the second winding shaft 42
Only the metallized film 30 is cut between the take-up shafts 41, the metallized film is braked, and only the laminated film is wound a predetermined number of times to obtain a capacitor element. The winding machine shown in FIGS. 4 and 5, the surface-modified PET film on the laminated film by the winding method, and the surface-modified P obtained by subjecting the surface-modified PET film of the present invention to the surface treatment.
An example of winding using an ET film is shown.

[0027]

[Table 2]

As shown in Table 2, surface-modified PET
When the film is used as a laminated film, the adhesion between the metallized film and the surface-modified PET film is so strong that when the metallized film is cut and only the laminated film is used as a protective winding, the metallized film is stretched or cut. Occurred, whereas
The laminated film and the metallized film using the surface-modified PET film of the present invention had good slipperiness and had no problem in the conventional winding machine.

FIG. 6 shows a film obtained by surface-treating the surface-modified PET film of the present invention by high-frequency corona treatment in air.
7 shows the life characteristics of a film capacitor manufactured using an untreated surface-modified PET film and a normal PET film.

1. Surface modified PET film surface treatment conditions a. Corona condition: power supply 500 (W), frequency 20 (KHz) b. Processing speed: 100 (m / min) c. Treatment side: One side 2. Capacitor specifications a. Method of forming capacitor element: winding method b. Film thickness: 5.9 (μm) c. Capacitor capacity C: 0.1 (μF) d. Rated voltage V: 400 (V) e. Exterior: Dip type resin exterior 3. Life test condition: 60 (° C) 95 (%) Constant temperature, constant humidity: Applied voltage DC (DC) 400 (V) In FIG. 6, the vertical axis represents the rate of change ΔC / C (%) with respect to the initial capacitor capacity, and the horizontal axis represents Indicates the test time under the life test condition. The symbol X indicates a normal PET film, the symbol O indicates a surface-modified PET film, and the symbol Δ indicates a film capacitor made of a surface-treated PET film surface-treated by high-frequency corona treatment in the atmosphere.

From the results of the life test shown in FIG. 6, it was found that a film capacitor made of ordinary PET film has a film capacitor of 20.
The capacity decreases after 0 hours of capacity measurement. Surface modified PE
The capacitance of the film capacitor made of T film is decreased after the capacity measurement with the test time of 800 hours. On the other hand, the film capacitor made of the PET film obtained by surface-treating the surface-modified PET film of the present invention by the high-frequency corona treatment in the air has a slightly increased capacity even after the test time of 800 hours, which is 1200 hours. A decrease in capacity was observed after the measurement. As a life characteristic of a general film capacitor, if the capacity starts to decrease after the capacity increases and further decreases, the test time at the time when the capacity decreases causes the life time to be the surface-treated surface-modified PET of the present invention. A film capacitor using a film has improved life characteristics with respect to capacitance change, thus enhancing the reliability of the film capacitor.

This result shows that the surface-modified PET film was surface-treated by high-frequency corona treatment, and as a result, the slipperiness between the metallized film and the laminated film was improved and the metallized film and the laminated film were simultaneously wound with the metallized film. It is considered that the laminated films can be wound evenly by slipping, and the film surface can have a high surface tension to improve the adhesion between the films in the heat pressing step. The effect of improving the moisture resistance is a major factor in improving the reliability of the film capacitor.

The same effect was obtained in the life test of the film capacitor by using the surface-modified PET film treated with oxygen plasma in vacuum.

The same effect can be obtained by high-frequency corona treatment or plasma treatment using a surface-modified polypropylene (PP), polyethylene naphthalate (PEN) or polyethylene sulfide (PPS) film. . Further, when the processing power is changed to 50 (W) as the condition of corona treatment and the treatment speed is changed to 100,
(M / min) has an effect of about 80%, and power supply is 2
When it was set to 00 (W), a similar effect was obtained at a processing speed of 200 (m / min). In these tests, the frequency of the supplied power may be a frequency for stabilizing the corona discharge in the gap between the electrodes, which may be 5 (KHz) to 75 (KH).
However, the effect was not different. In the detailed description of the present invention, specific dimensions, material names, and process conditions have been described, but the present invention is not limited to these.

[0035]

As described above, according to the present invention, the following effects can be obtained by subjecting the surface-modified PET film to the electric discharge treatment.

1. By reducing the charge amount of the surface-modified PET film, the workability of winding for manufacturing the film capacitor element can be remarkably improved.

2.60 (° C.) 95 (%) The capacity reduction start time in the life test under constant temperature and humidity can be extended, and the durability in actual use can be improved.

3. Therefore, the production yield can be improved and the production cost can be reduced to provide a high-performance and inexpensive film capacitor.

4. The surface treatment method is simple and highly industrial.

[Brief description of drawings]

FIG. 1A is a sectional view showing a normal film and a surface-modified film. FIG. 1B is a sectional view showing a normal film and a surface-modified film.

FIG. 2 is a schematic diagram showing an example of a surface treatment method of a surface modified film by oxygen plasma in a vacuum.

FIG. 3 is a schematic diagram showing an example of a surface treatment method for a surface-modified film by high-frequency corona treatment in air.

FIG. 4 is a schematic view showing an example of a film capacitor winding machine.

FIG. 5 is a schematic view showing an example of a film capacitor winding machine.

FIG. 6 is a characteristic diagram showing a life test result of a film capacitor using the surface-modified PET film of the present invention, a film capacitor using the surface-modified PET film, and a film capacitor using a normal PET film.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 PET film 2 Surface modification layer 7,16 Surface modification PET film 8 Discharge electrode 21,22 Corona surface treatment roll 30 Metallized film

Claims (3)

[Claims] 1. A surface-modified film obtained by forming a surface-modified layer of a coating material containing a polymer material having one or both of urethane bond and ester bond as a main component on the surface of a film made of a polymer material. , A method for producing a film for a film capacitor, wherein the surface of the film is subjected to electric discharge treatment while the surface-modified film is running. 2. The method for producing a film for a film capacitor according to claim 1, wherein the discharge treatment is plasma treatment under reduced pressure or high frequency corona treatment in the atmosphere. 3. A surface modification layer is formed on a surface of a film made of a polymer material by a coating material containing a polymer material having one or both of urethane bond and ester bond as a main component, and discharge of the surface. A method for producing a film for a film capacitor, which comprises forming a surface-modified film by adjusting a charge amount by treatment and winding or laminating the surface-modified film.