JPS6064421A - Metallized film capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a dielectric composite layer having a high dielectric constant mixed with a polymer and a high dielectric constant powder on at least piece 1 (11) of a double-sided metallized film. The present invention relates to formed metallized film capacitors.

Conventional structure and problems Currently, polyethylene terephthalate and polypropylene are used as dielectric materials for metallized film capacitors.

Films such as polycarbonate are widely used.

Although these films have a low tan δ compared to other dielectrics, they also have a low dielectric constant, which is insufficient to meet the recent needs for smaller capacitors and resource conservation. Not being able to respond. In order to increase the dielectric constant of a dielectric material, attempts have been made to incorporate powder of a high dielectric constant H material into a polymer. For example, powder of a high dielectric constant material such as barium titanate, calcium titanate, or titanium oxide is mixed with a polymer such as polyethylene or polyester. According to this method,
It is certainly possible to increase the dielectric constant.

However, there was a drawback that tan δ was extremely high.

Purpose of the Invention The present invention solves the drawbacks of such composite dielectrics by
By forming this f'L on one side or both sides of a double-sided metallized film, a small and inexpensive metallized film capacitor can be made into an complex. The purpose is to

Structure of the Invention To achieve this objective, the present invention involves coating the individual surfaces of a high dielectric constant powder with an organosilicon compound, and mixing this surface-treated powder into a polymer to form a composite dielectric layer. year,
By forming this composite dielectric layer on at least one side of a double-sided metallized film and winding or laminating it, a metallized film capacitor with a small tan δ can be constructed.

Examples of silicon compounds that can be used in the present invention include methyltriethoxysilane.

Examples include dimethyljethoxysilane, γ-methacryloxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane 7, and the like. Note that the present invention is not limited to these silicon compounds.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3 of the drawings.

FIG. 1 shows the volume resistivity of titanium oxide (Ti0z) powder when the surface is treated with a silicon compound (M) and when it is untreated (B). As is clear from this figure, when the surface is treated with a silicon compound, the volume resistivity of the powder becomes several orders of magnitude higher than when it is untreated.

Figure 2 shows the experimental results, with frequency f (KHz) plotted on the horizontal axis and tan δ (%) on the vertical axis, showing that the tan δ of the composite dielectric varies greatly depending on the presence or absence of surface treatment of the powder with a silicon compound. . This is Ti on polycarbonate.
When O2 is mixed (33vOε%), curve B shows the case with surface treatment, and curve B shows the case without surface treatment. From Figure 2, it can be seen that tanδ is greatly reduced by surface treatment, but as shown in Figure 1, this is due to the
This is due to a significant improvement in the volume resistivity of the powder.

Polymers include unsaturated polyester, polybutadiene,
Resins such as polycarbonate and polyphenylene oxide are used, and these are made into a liquid state, and surface-treated powders such as barium titanate (BaTi03) and calcium titanate (CaTi03) + TiO2 are mixed therein. When mixing, dispersants and additives are also used as necessary.

In the capacitor of this embodiment, a composite dielectric layer 2 containing a high dielectric constant powder coated with the silicon compound is formed on both sides or one side of a double-sided metallized film 1 as shown in FIG. 3, and is wound or laminated. It is composed of

Further specific examples will be described in detail.

Example 1 A double-sided metallized film 1 obtained by vacuum-depositing aluminum on both sides of a 5 μm thick polyethylene terephthalate film was used as a substrate film, and a 3 μm thick polyethylene terephthalate film was used as a substrate film.
A composite dielectric layer 2 of m was formed. The composite dielectric layer 2 was made of polycarbonate (polycarbonate) -TiO2, and the volume ratio of TiO2 was 35%. The surface treatment of TlO2 was carried out using methyltriethoxysilane, and a silane treatment solution was prepared so that the amount of silane was 1 liter per weight of TiO2, and after thorough stirring and mixing, it was heated and dried. The recarbonate-resistant material was dissolved in dichloromethane (j1/rL), and C) surface-treated TiO2 powder having an average particle size of 0.3 μm was dispersed. The composite dielectric layer 2 was formed on the substrate film 1 using a reverse roll coating method.

Thereafter, a wound capacitor (10 μF) was formed by drying, winding, and slitting.

Example 2 A composite dielectric layer 2 having a thickness of 6 μm was formed on one side of a substrate film 1 similar to that in Example 1. The composite dielectric layer 2 was made of an unsaturated polyester resin-BaTiOs system, and the volume ratio of BaTiO3 was 30%. The surface treatment of the BaTi05 powder was carried out in the same manner as in Example 1 using γ-methacryloxypropyltrimethoxysilane. Penzole peroxide was used as a curing agent for the unsaturated polyester resin. The formation of the composite dielectric layer 2 on the substrate film 1 was also performed in Example 1.
A wound type capacitor (10 μF) was formed by the same method as above, and the composite dielectric layer 2 was cured, rolled up nine times, and subjected to a slitting process.

The experimental results of Example 1 and Example 2 are shown in the following table.

(The specific dielectric constant of the composite dielectric material is significantly improved compared to 2 to 3 of the commonly used dielectric film, and
It can be seen that the tan δ of the composite dielectric material 2 is also significantly lower than that of the untreated high dielectric constant powder.

Effects of the Invention As described above, according to the present invention, a composite dielectric with low loss and high dielectric constant can be obtained, and by forming this on a double-sided metallized film and winding or laminating it, the capacitor can be greatly improved. This has an excellent effect of reducing the size and cost.

[Brief explanation of drawings]

Figure 1 is a characteristic diagram showing the volume resistivity of high dielectric constant powder with and without surface treatment, Figure 2 is a characteristic diagram showing changes in tan δ of a composite dielectric layer with and without surface treatment of the powder, and Figure 3 The figure is a sectional view of a main part of a metallized film capacitor according to an embodiment of the present invention in which composite dielectric layers are formed on both sides. 1... Double-sided metallized film, 2... Composite dielectric layer.

Claims (1)

[Claims] A metallized film capacitor in which a composite dielectric layer is formed on at least one side of a double-sided metallized film, the surface of which is coated with an organic silicon compound and a composite dielectric layer is formed by mixing a polymer with a high dielectric constant powder, which is wound or laminated.