JP3074903B2 - Dielectric film for capacitors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric film for a capacitor, and more particularly to a dielectric film for a capacitor which can be used for a film capacitor used in electronic equipment and electric equipment.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become extremely compact and cost-effective, the size and cost of electronic components have been increasing with the increasing density of electronic components using surface mounting technology. The demand for cost reduction is becoming severe. Among them,
Similarly, development of miniaturized products for capacitors has been progressing one after another. In particular, conventionally used film capacitors use polyethylene terephthalate, polyphenylene sulphite, polyethylene naphthalate, etc. as a base film, aluminum is vapor-deposited on both sides thereof, and furthermore, polycarbonate, polyphenylene oxide, etc. are used as a dielectric. Is dissolved in an organic solvent and then coated, and a dielectric film for a capacitor formed as a dielectric layer has been used. On the other hand, in recent years, there has been a growing desire to review the use of organic solvents in the entire industry from the viewpoint of waste of resources, toxicity, and cost, and there has been a strong demand for reduction. .

[0003] A conventional dielectric film for a capacitor will be described below. In FIG. 2, 11
Is a base film, 12 and 13 are vapor-deposited metals, and 14 and 15
Is a dielectric layer. Aluminum is first vapor-deposited on the wide and long base film 11 at the position 12, and then shifted to the back 13 by the margin width, and then aluminum is vapor-deposited in the same manner. The dielectric layer 14 is applied after covering a part of the base film 11. After the application of this surface is completed, 14
A dielectric layer is applied to a position that coincides with the surface of the dielectric layer to form a dielectric film for a capacitor. In addition, polycarbonate or polyphenylene oxide is dissolved in an organic solvent to form a 5 to 20% solution. The organic solvent used is dichloromethane, 1,2-dichloroethane,
1,1,1-trichloroethane, trichloroethylene,
Toluene is used.

[0004]

However, in the conventional dielectric film for a capacitor, the dielectric layer is formed by dissolving the compound used for the dielectric in an organic solvent and then coating as described above. According to this method using an organic solvent, (1) when the organic solvent is volatilized, a considerable amount of gas is released into the atmosphere. (2) Poisoning due to the generation of toxic gas may cause damage (3). The cost of the organic solvent itself is high. (4) In the organic solvent recovery step, there are problems such as a large amount of energy consumption and a large cost in the process of refining the organic solvent. In order to solve this problem, (5) coating with a water-soluble paint (6) use of a thermosetting resin as disclosed in JP-A-61-279110 (7) Japanese Patent Publication No. 60-1
Japanese Patent Application Laid-Open No. 57106 discloses a method of forming a dielectric by electron beam curing, which has the following problems. The coating of the water-soluble paint of (5) requires a small amount of water-soluble paint that can be used for a capacitor, and this requires a treatment to reduce the hygroscopicity. Also,
The energy for evaporating water and the cost of the waste liquid treatment process are high, and the use of the thermosetting resin of (6) requires a considerable amount of heat energy for curing, and the base film needs heat. Causes uneven shrinkage, resulting in poor quality such as dimensions. In the electron beam curing of (7), since a dielectric is formed under vacuum, there is a problem that a large investment is required for capital investment. SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and to provide a resource-saving and inexpensive dielectric film for capacitors by directly applying an ultraviolet curable resin to a double-sided metallized film.

[0005]

In order to achieve this object, a dielectric film for a capacitor according to the present invention is directly formed into a thin film by using an ultraviolet curable resin having a very special structure without using any organic solvent. It becomes possible to form a dielectric layer, and by irradiating ultraviolet rays under a low oxygen concentration, a dielectric film for a capacitor having a low-cost, high-quality, resource-saving dielectric layer of a UV-curable resin is formed. is there.

[0006]

According to the present invention, a compound having the structure shown in Chemical formula 2 and having 7 to 12 methylene groups between acrylate groups, or a saturated aliphatic cyclic hydrocarbon skeleton in the main chain. By using a compound having an ester group with an acryloyl group in two side chains alone or in combination, the coating technology such as the gravure method and the die coating method can be used without using a solvent. By adopting it, it becomes possible to form a thin film of 1 μm or less,
In addition, since the curing shrinkage is small, a dielectric film for a capacitor with less wrinkling is obtained.

[0007]

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In general, the ultraviolet curing reaction is slower than the electron beam curing, and is not suitable for film production. Further, since the viscosity is high, it is difficult to form a thin film, the surface reactivity is poor, and the tackiness is poor. Or hardening shrinkage is large,
Film wrinkling easily occurred, and a high quality dielectric film for capacitors could not be obtained. In particular, a compound having a structure represented by (Chemical Formula 2) in which n is 6 or less had a large curing shrinkage and a dielectric loss angle exceeding 0.01.
On the other hand, when n was 13 or more, thin film coating was not possible, and the curing speed was extremely slow. Those having n of 7 or more and 12 or less and those having a saturated aliphatic cyclic hydrocarbon skeleton in the main chain have a solvent-free coating of 1.0%.
A thin film having a thickness of less than μm can be formed, and the dielectric loss angle is not more than 0.1 μm.
It has been found that a large amount of resin having a size of 009 or less can be applied in a length direction at a speed of 150 m / min and cured with ultraviolet rays under a low oxygen concentration.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A dielectric film for a capacitor according to one embodiment of the present invention will be described below with reference to the drawings.

(Example 1) In FIG. 1, 1 is a base film, 2 and 3 are deposition electrodes, 4, 5 are dielectric layers, and 6, 7
Is an external electrode.

Next, a description will be given based on a specific embodiment. A two-phase sensitizer (2 parts of sensitizer per 100 parts of resin) added to ultraviolet curable nonamethylene methylene diol diacrylate has a length of 1,000 m, a width of 5 mm, and a thickness of 4.0 μm. One side of the aluminum vapor-deposited film was applied with a gravure coater to a thickness of 1.0 μm. This film was run at a speed of 150 m / min, filled with nitrogen gas, and in an atmosphere having an oxygen concentration of 1000 ppm.
The sheet was irradiated with ultraviolet rays having an intensity of 10 mW / cm ² through a wide area for 1 second and then wound up. After irradiation on one side, coating and ultraviolet irradiation were performed on the other side under the same conditions to obtain a dielectric film for a capacitor. Next, a predetermined number of dielectric films for capacitors cut to predetermined dimensions were laminated, and metallicons were sprayed as external electrodes to form capacitors. The capacitance of the capacitor obtained by this method is 117.0 nF, 1
The dielectric loss (tan δ) at kHz was 0.5%, and the withstand voltage was 390 V on average. Capacitors of the same dimensions were manufactured for heptamethylene diacrylate and dodecamethylene diacrylate, and similar characteristics were obtained. In addition, on one side of the double-sided metallized film, applied in a thickness of 2.0μm, using a capacitor film obtained by ultraviolet curing,
Those manufactured under the same conditions also obtained similar results.

Example 2 An electrode was prepared by the same operation as in Example 1 except that a sensitizer was added to the ultraviolet-curable resin dimethylol tricyclodecane diacrylate at 2 phr. The capacitance of this capacitor is 10
The dielectric loss (tan δ) at 1.2 nF and 1 kHz was 0.5%, and the withstand voltage was 370 V on average. Also, capacitors of the same dimensions were manufactured for isobornyl diol diacrylate, and almost the same characteristics were obtained.

(Example 3) A capacitor having the same dimensions as that of (Example 1) was prepared by mixing nonanemethylenediol diacrylate and dimethylol tricyclodecane diacrylate in equal amounts, and adding 2 phr of a sensitizer. . The capacitance of this capacitor is 108.5 nF, the dielectric loss (tan δ) at 1 kHz is 0.5%, and the withstand voltage is 3 on average.
It was 80V.

(Comparative Example 1) According to the conventional example, a solution prepared by dissolving polycarbonate in a mixed solvent of dichloromethane and 1,2-dichloroethane to form a 16% by weight solution was formed on the same film as in Example 1 with the same thickness. After coating, the mixed solvent was volatilized and dried to obtain a dielectric film for a capacitor. Using this, a capacitor having the dimensions shown in (Example 1) was manufactured. The capacitance when this capacitor is manufactured is 91.55 nF, the dielectric loss (ta) at 1 kHz.
nδ) was 0.3%, and the withstand voltage was 300 V on average.

As described above, the characteristics of the laminated film capacitor obtained by using the dielectric film for a capacitor according to the embodiment are as follows: the withstand voltage is improved and the relative dielectric constant is large as compared with the comparative example. Furthermore, there is an effect that a capacitor having the same shape and a larger capacity can be obtained.

[0016]

As apparent from the above description of the embodiments, according to the dielectric film for a capacitor of the present invention, a large amount of dielectric film for a capacitor can be produced at a time with high quality, low cost and resource saving. it can. In addition, since coating can be performed without using a solvent, a film having a small variation in thickness can be formed, and pinholes do not occur when the solvent is volatilized, thereby improving withstand voltage characteristics. Further, since the curing shrinkage due to the ultraviolet irradiation is smaller than the shrinkage due to the solvent volatilization, the film does not wrinkle and the change in dimensions is particularly small, so that a high quality dielectric film for capacitors can be formed. In addition, since diacrylate has a high relative dielectric constant, the capacity per one film is improved as compared with the related art. These things are of great industrial value.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a configuration of a dielectric film for a capacitor according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a configuration in a width direction of a conventional dielectric film for a capacitor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base film 2, 3 Deposition electrode 4, 5 Dielectric layer 6, 7 External electrode

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-60-157106 (JP, A) JP-A-62-256421 (JP, A) JP-A-3-246814 (JP, A) JP-A-4- 28107 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01G 4/00-4/40

Claims (1)

(57) [Claims] 1. A compound having a structure represented by the formula (1), wherein the number of methylene groups between acrylate groups is 7 or more and 12 or less, or a compound having a saturated aliphatic cyclic hydrocarbon skeleton in the main chain, A compound having an ester atom group having an acryloyl group in two side chains may be used alone or in combination, and the ultraviolet-irradiated dielectric layer of a thin film made of a solvent-free UV-curable resin containing these may be used. And a dielectric film for a capacitor formed on at least one of the double-sided metallized films. Embedded image