JPS61212011A - Oil-filled 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 [Industrial Field of Application] The present invention relates to an oil-immersed capacitor using a metal vapor deposited layer as an electrode.

[Conventional technology]

Conventionally, oil-immersed capacitors are known in which a plastic film, particularly a polypropylene film, is used as a dielectric material, and a metal vapor-deposited on the film is used as an electrode (for example, Japanese Patent Laid-Open No. 59-39017).

(Problems to be Solved by the Invention) However, although this conventional technique improves the impregnating properties of electrical insulating oil, changing the type of oil depending on the required characteristics of the capacitor causes the dielectric to swell significantly. However, when the dielectric material swells significantly due to long-term use at high temperatures, cracks often occur in the metal deposited film formed as the electrode.

The present invention does not have the problems of the prior art, i.e., uses dioctyl phthalate, diisononyl phthalate [-, etc.], which have problems in application as electrical insulating oil in flat, fully impregnated vapor-deposited polypropylene film capacitors. The object of the present invention is to provide an oil-immersed capacitor which has a longer service life when used, and which is less likely to cause cracks in the metal vapor deposited layer even if the dielectric material expands.

(Means for Solving the Problems) The present invention provides an oil immersion capacitor in which a film mainly made of polypropylene is used as a dielectric and a metal layer deposited on at least one side of the film is used as an electrode. The film has a rough surface with a surface length index of 1 to 7 on the metal layer side, and has an M value of 3 to 50 (q/100in2/24hr10
．． 001 in).

M= (-10(J P)
001 in).

The polypropylene-based film in the present invention is one whose surface has been roughened at least on one side by the method described below. In other words, inorganic or organic particles are added to polypropylene, cast, 21111-stretched, those with surface irregularities caused by the change in shape from 3 to α, and melting of two components mixed in at least the surface layer. These include those with rough surfaces caused by tension differences.

Describing specific examples of the film of the present invention, for example,
Isotactic degree (hereinafter abbreviated as II) is 96-99.
A film made of 5% polypropylene homopolymer transformed into a rough surface, or a film with an II of 96 to 99.6
% of polypropylene (A>) and 10.% of polypropylene (A>) containing ethylene.
7-2.5 wt% ethylene propylene random copolymer 70-B 5 wt% is polymerized with 15-30 wt% ethylene, and 1q II is laminated with 85-95% ethylene propylene block copolymer (B). , biaxially stretched films are typical examples.
In the latter case, the thickness of polypropylene (A) and the copolymer (B
) preferably has a weight ratio (A/B) of 80/20 to 9515.

Note that other polymers may be copolymerized or mixed in this film as long as they do not impair the effects of the present invention, but it is preferable that the polypropylene content in the film is 80 wt % or more. Further, a film whose rough surface side is subjected to a corona discharge treatment to have a wetting tension of 40 to 46 dyne/cm is preferable.

In the film of the present invention, either or both of the surface layers may be roughened, but a composite roughened film is better than a single layer roughened film. preferable.

The metal-deposited side of the film of the present invention has a surface length index of 1 to
7, preferably 2-5. Also, Mliiff calculated by the following formula is 3 to 50C1/100
Must be in2/24hr10.001 in.

M= (-togP)x, where L: surface length index P: permeability coefficient Cg/100in2/24hr10.
001 in) Note that the surface length index is an approximation index of the ratio of the length of the deposition surface to the unit length of the film, which is determined by the following equation.

L=100HxN/D.

However, H: average height of protrusions mm > N: number of protrusions present in length α (pieces/mm) U:
Film length mm > Average height and number of protrusions are measured as described below.

The above surface length index (hereinafter simply referred to as L value) is 1
If it is less than 7, the oil impregnation property and the stability of the deposited film will be poor.
If it exceeds this value, the withstand voltage characteristics will deteriorate and this is not preferable.

In addition, the permeability coefficient P is a coefficient derived from the following formula,
In the present invention, a value of 23°C is used.

1 (Xll P= -Rπ Where, P: Permeability coefficient (g/100in2/24hr/0.00
1in) K: Temperature correction constant [] R Niblastic characteristic value (〃) π: Value determined by molecule or group The above formula is described in PLASTIC3, MAY 1965, where P is the film stability and There is a good correlation, and a value of less than 0.1 is preferable, and a value of 0.1 or more is not preferable because it tends to cause cracks in the deposited film.In the case of polypropylene, the temperature correction constant has a relationship with temperature as shown in the following equation.

K=0.0286t+3.532 Where, t: Temperature (°C) (23°C is used in the present invention) The plastic property value R is 0.26 for polypropylene. π is called PERMAcHORVALUE and is determined by the molecule or group. The main ones are shown in Table 1.

In addition, in the case of the film of the present invention, the values of K and R are the same as those of the above-mentioned polypropylene.

In the present invention, as described above, M calculated based on P
Value (unit: Q/100in2/24hr10°001
If in> is less than 3, the deposited film tends to crack,
If it exceeds 50, it becomes highly viscous and impregnating properties become poor, so the M value must be between 3 and 50.

The thickness of the film in the present invention is not particularly limited, but is preferably 6 to 30 μm. Furthermore, in the case of a single layer, the film in the present invention is preferably biaxially stretched.
In the case of lamination, it is preferred that at least the polypropylene (A> layer) be biaxially stretched.

The dielectric of the present invention may be the above-mentioned film alone, or may be a laminate with other films or paper.

The vapor-deposited metal layer of the present invention is a layer made of various metals, preferably Zn or A1, vapor-deposited by a known method, and the thickness of the layer is not particularly limited, but is 100 to 30%
00 people is preferred. If the thickness is less than 100, the film strength will be weak, and if it is more than 300, the self-healing property will be poor, which is not preferable.

The electrical insulating oil used in the present invention may be any electrically insulating oil or a mixture thereof, but it is necessary to select one whose M value falls within a predetermined range. In addition, preferable insulating oils include dioctyl phthalate, tricresyl phosphate, vegetable oil (a mixture of fatty acids such as behenic acid and oleic acid), and the like.

Next, an example of a film on which a metal vapor deposited layer of the present invention is formed and a method for manufacturing an oil-immersed capacitor using the film will be described.

First, a film is manufactured as follows. II is 98
~99.6% PP was fed into an extruder heated to 240-280'C and dissolved.

On the other hand, II obtained by polymerizing 15 to 30 wt% of ethylene to 70 to 85 wt% of ethylene propylene random copolymer containing 10.7 to 2.5 vyt% of ethylene was 8
5-95% ethylene propylene block copolymer
Dissolved at 40-270°C.

These two polymers are 400 to 800
It was extruded into a sheet shape corresponding to .mu., wound around a chill roll with a surface temperature of 20 to 40'C, and cooled and solidified. This laminated sheet was heated at a temperature of 130 to 155°C with a temperature of 4.0 to 5.0°C in the longitudinal direction.
After stretching 5 times, 155 to 175 degrees in the perpendicular direction
145-160 after stretching 7.0-11.0 times at a temperature of C
A film with a rough surface formed on the copolymer layer side is obtained by heat treatment with slight relaxation at a temperature of 1.5 C, and a corona discharge treatment is performed on the rough surface side of the film to reduce the wetting tension of the surface to 40 to 4.
After adjusting to 6 dyne/Cm, wind it up.

Note that the film may be made as follows.

A PP homopolymer with II of 96 to 99.5% and a small amount of organic nucleating agent added thereto is melted at an extrusion temperature of 250 to 270°C and brought into contact with a chill roll heated to 80 to 90'C to form a 400 to 800μ Solidify into a sheet of 150 ~
After obtaining a roughened film by relaxation heat treatment at a temperature of 160'C, the film surface was heated to 40-46 dyne by corona discharge.
It is processed to a wetting tension of 1.5 cm and wound up.

A1 or Zn is deposited to a thickness of 100 to 300 layers on the rough side of the film formed as described above to obtain a film with a metal layer formed thereon.

Next, two films with the metal layer formed thereon are stacked to obtain a wound element capacitor. Zn, AI, Pb, Sn, or an alloy thereof is metallized on both ends of this element capacitor, terminals are attached to both sides of the metallized portion, and the capacitor thus formed is placed in a container and vacuum dried. Add insulating oil dehydrated by vacuum or adsorption to an unimpregnated capacitor at a rate of 50 to 9
At a pressure below 0'C, 0°1 mmHo abs, 24
After being impregnated for more than hr, it is sealed in oil to obtain an oil-immersed capacitor.

The method for measuring and evaluating characteristic values of the present invention is as follows.

(1) Number of protrusions, height of protrusions The surface of the film is measured under the following conditions using a three-dimensional universal surface shape measuring device with an analyzer (100EL 5E-3FKS manufactured by Koita Research Institute Co., Ltd.).

Measurement length: 1mm Vertical magnification: 5000x Lateral magnification: 200x Feed speed: 0.11Tlffl/SeC filter:
0.25mm Measurement interval: 10μ Number of measurements = 20 From the number of peaks obtained under the above conditions PC-1, the height of the peak is 0.2μ
The above number is called the number of protrusions. Here, PC-1 refers to the number of protrusions having a height of O02μ02μ from the center line of the surface irregularities. The average height H is calculated by counting the protrusion height in 002μ increments, for example, all the protrusions between O12 and 0.4μ as the height of the center value, e.g. 0.3μ, and calculating the number of protrusions corresponding to the center value. The total number of protrusions is divided by the total number of protrusions measured under the above conditions, multiplied by the height (center value) of the protrusions described above.

(2) Change in membrane resistance Measuring was carried out using Yokogawa Electric Corporation's Portaple and Wheatstone Bridge in the following manner. Cut the vapor-deposited film into lengths of 25 cm on one side and 3 cm on the other, and let R1 be the resistance at a distance of 20 cm between the electrodes, and R2 be the resistance at the midpoint, that is, 1Q cm.The resistance of the vapor-deposited surface is R, ( Ω/mouth) = [R+-R2/20-10]
xW However, W is determined by the film width (here, 3 cm). Similarly, the membrane resistance after the oil immersion treatment was measured, and the membrane resistance change was determined by dividing the membrane resistance after the oil immersion treatment by the membrane resistance before the oil immersion treatment.

Note that the measurement was performed three times and the average value was taken as the average value.

(3) Stability of deposited film in oil In insulating oil such as phenylxylylethane, dioctyl phthalate, tricresyl phosphate, vegetable oil (mixture of fatty acids such as behenic acid and oleic acid), alkylbenzene, monoisopropylbiphenyl, etc. , 80-100℃
The deposited film was immersed for 24 to 72 hours, and the rate of change in film resistance after immersion and the change in the deposited film were observed using a microscope. The criteria for evaluating the stability of a deposited film were that the film resistance change rate was 10% or less and that there were no cracks in a 125x enlarged photograph.

〔Example〕

Next, actual tM aspects of the present invention will be explained based on examples.

Example 1.2, Comparative Example 1 Extrusion 111 Temperature 250'C Temperature 99.2% (7)
Melting PP homopolymer and ethylene content 1.2w
t% ethylene propylene random copolymer is 85wt
A block copolymer of ethylene propylene with II of 92% obtained by polymerization at a blending ratio of % and ethylene was melted at an extruder temperature of 250°C. After extruding into a sheet from a T-die of RNM and cooling and solidifying it with a chill roll cooled to 30°C, it was heated to a temperature of 140°C with a 5.0
In Example 1, 17
Stretched 9.0 times at a temperature of 5°C, and 156°C in Example 2.
After being subjected to relaxation heat treatment at 11155° C., the rough side was set to a wetting tension of 43 dyne/cm by corona discharge and wound up. After slitting this film, the film thickness is 150-20
A1 of 0 was vacuum deposited on the rough surface side.

Comparative Example 1 was prepared in the same manner as above, and the stretching temperature in the orthogonal direction was 149°C. Table 2 shows the characteristic values and M value of the metallized polypropylene film obtained by the above method.

Note that an example of calculating the M value in Table 2 is shown.

In the case of phenylxylylethane and an L value of 4.5, π is calculated from Table 1 as follows: Phenyl group 5.4X2=10.8 Carbon group 1.0X4=4.0 Branch
2゜0X1= 2゜Oπ=
We get 16.8. At 23°C, the value is 4.2, R is 0.26, and when these are substituted into the formula for calculating logP, 10a p = 4
．． 2-0.26 x 1.6B =-0,168=-
We get 0.17.

From this value and L value, M = -1 (XIP XL = 0.17 x 4.5 =
We get 0.765=0.8.

All M values in Table 2 were determined in this manner.

A capacitor having each M value shown in Table 2 was used, and after being immersed in insulating oil at 80° C. for 24 hours, the resistance change of the metal deposited film was measured, and the results are shown in FIG. As is clear from the figure, those with an M value of 3 or more do not cause any change in membrane resistance and are found to have excellent membrane stability. ND in the figure indicates that the rate of change was too large to be measured, and in the figure, ◯ indicates Example 1, mouth indicates Example 2, and Δ indicates Comparative Example 1.

An example of the surface state of the metal-deposited film used in the measurement of the metal-deposited olfactory resistance change is shown in FIGS. 2 (1) to (4).

(1) and (3) use vegetable oil, (2) and (4) use phenylxylylethane, and those with L of 0.5 cause cracks in the deposited film even in vegetable oil, which has a relatively small permeability coefficient. Insulating oils with extremely small P, i.e., insulating oils consisting of macromolecules, will not cause cracks in the deposited film even when combined with those with small L, but together with their high viscosity, impregnation and handling properties will be affected. (Figure 2 is a sketch of a photograph of the deposited film at 125x magnification).

Example 3, Comparative Example 2 I with 0.03% quinacridone added at an extrusion temperature of 260°C
A PP homopolymer with an I of 97.5% was melted, and the melt was passed through a T-die with a width of 620 ROM and a gap of 1.2 mm.
It was extruded into a sheet, brought into contact with a chill roll heated to 90°C, and the 750μ sheet was cooled and solidified.
Stretched 5.0 times in the longitudinal direction at a temperature of 5°C and 10.0 times in the perpendicular direction at a temperature of 165°C,
After that, the film surface on the non-contact side of the chill roll was heated to 43 dyne using a corona discharge.
It was wound up to a wetting tension of /Cm. After slitting this film, a layer of AI with a thickness of 150 to 200 people was vacuum-deposited.
child.

In Comparative Example 2, II was 97.5% and the chill roll temperature was 50°C.
The other conditions were created in the same manner as above. L of the metallized polypropylene film obtained by the above method
The values and M values are shown in Table 3.

These metallized films were subjected to an oil resistance test under the conditions of 80°C and 24 hours, and as a result, the results showed ○, △, × in Table 3.
The results shown were obtained. In Table 3, ○ indicates that no film change or cracks occur at all, △ indicates that the state is almost the same as (1) in Figure 2, and × indicates that severe film cracks occur as shown in (2) of Figure 2. Indicates that the resulting membrane resistance cannot be measured. As is clear from the above, no matter how the F)P film is made, those with an M value of 3 or more have excellent film stability in oil, and as the M value decreases, film cracking becomes less likely. It turns out that this is more likely to occur.

〔Effect of the invention〕

As mentioned above, in the present invention, the surface length index of the dielectric material and the M value obtained from the dielectric material and the insulating oil are set to specific values, so the range of applicable oil types is widened, and the metal vapor deposition layer is cracked. We were able to obtain an oil-immersed capacitor that is resistant to oil.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between M value and metal deposited film resistance;
The figure is a diagram showing the occurrence of cracks in the deposited metal film. Patent Applicant Toshi Co., Ltd. Written Amendment to Procedures 1. Display of the case 1985 Patent Application No. 52547 2, Name of the invention Oil immersed condenser 3, Person making the amendment Relationship to the case Patent applicant address 2-2-5 Nihonbashi Muromachi, Chuo-ku, Tokyo Inventions increased by the amendment No. 6, "Detailed Description of the Invention" column of the specification to be amended 7゜Contents of the amendment (1) "Polypropylene" in the 6th line from the bottom of page 7 of the specification is amended to read "in the case of polypropylene" . (2) 3rd line from the bottom of page 13 “R1 (Ω/mouth) = [R+-R:)/20-10]
xWJ to rR, (Ω/mouth) = [(R+-R2)/
(20-Oct.

Claims (1)

[Claims] (1) An oil-immersed capacitor in which a film mainly made of polypropylene is used as a dielectric and a metal layer deposited on at least one side of the film is used as an electrode.
The film has a rough surface with a surface length index of 1 to 7 on the side of the deposited metal layer, and has an M value of 3 to 50 [g/100in^2/24hr/0. 00
1 inch]. M=(-logP)×L However, L: Surface length index P: Oil permeability coefficient [g/100in^2/24hr/0
．． 001in]