JPS6260214A - 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 Application Field] The present invention relates to a capacitor, and more particularly to a capacitor in which insulating layer films and metal layers are alternately laminated.

[Prior art]

Capacitors are generally manufactured using a method in which a film such as a biaxially oriented polyethylene terephthalate film or a biaxially oriented polypropylene film is overlaid and wound with a metal foil film such as an aluminum foil, or the surface iCC of the film is
It is manufactured by forming a vapor-deposited film of zinc or the like and then winding it.

In particular, recently, with the demand for miniaturization of electric or electronic circuits, there has been a strong push toward miniaturization of capacitors, and their main materials, polyethylene terephthalate film and polypropylene film, are also being made thinner.

Along with the trend toward thinner films, it has been found that simply reducing the thickness of conventional biaxially oriented polyethylene terephthalate films, biaxially oriented polypropylene films, etc. has the following problems.

For example, as the film tends to become thinner, workability during processes such as when depositing electrodes on the film, when slitting, and when winding an element becomes worse.

There are two types of workability: one is related to the slip property of the film, and the other is related to the stiffness of the film.

In order to improve the slip properties of a film, it is sufficient to provide minute irregularities on the film surface. Conventional techniques include adding inert inorganic fRa particles uniformly or using an internal precipitation method to precipitate particles during polymerization. It has been known.

If the number of protrusions in the film is increased), not only will the electrical properties of the capacitor (e.g. dielectric strength) become inferior, but also the film will become more likely to break during film formation, making it difficult for the film to become a stable insulating layer. You will not be able to obtain

In addition, conventional biaxially oriented polyethylene terephthalate films and biaxially oriented polypropylene films are not only stiff and difficult to handle, but also wrinkles occur during vacuum deposition, and the film stretches vertically during the deposition process, resulting in a uniform product. In extreme cases, it may break.

In order to increase the rigidity of these films (increase stiffness), it is necessary to increase the stretching ratio, but this is not easy if the film is thin.

Further, for example, conventional biaxially oriented polyethylene terephthalate films and biaxially oriented polypropylene films both have insufficient heat resistance, with a normal operating temperature of 85°C or lower and a maximum operating temperature of about 125°C. Therefore, the electrical characteristics during high-temperature use were also not good.

[Purpose of the invention]

An object of the present invention is to eliminate the above-mentioned drawbacks and provide a capacitor that is easy to work with and has excellent electrical characteristics at high temperatures.

[Structure of the invention]

As a result of extensive research into a capacitor that has excellent workability and can maintain excellent electrical properties up to high temperatures, the inventors of the present invention discovered that polyethylene-2,6-natutaledicarphochelate (polyethylene -2,6-naphthalate (abbreviated as PEN) and by adjusting its surface roughness, strength, and heat shrinkage rate, the present invention was achieved based on the finding that the above characteristics can be simultaneously satisfied. It is something.

That is, the present invention provides a capacitor in which an insulating layer made of a biaxially oriented PEN film and a metal layer are laminated.
Biaxially oriented PEN whose surface roughness is o, oisμ
m or more o, os.

μllI or less, and the Young's modulus in the longitudinal direction is 600 Yu/
temperature or higher, and a denser at 150°C for 30 minutes.

The PBN referred to in the present invention may be one whose repeating structural unit is substantially composed of ethylene 2,6-naphthalate units, and which is a non-copolymerized polyethylene-2,6-naphthalate unit.
It includes not only 2,6-naphthalate but also ethylene-2,6-naphthalate copolymers and polymer mixtures in which the number of repeating structural units is 10 or less, preferably 5 or less, as other components.

Generally, polyethylene-2,6-7-talate is prepared by combining naphthalene-2,6-dicarboxylic acid, or a functional derivative thereof, and ethylene glycol or a functional derivative thereof under appropriate reaction conditions in the presence of a catalyst. However, the polyethylene-2 referred to in the present invention,
A suitable third component (modifier) of one or more types is added to the 6-s7 tallate before the polymerization of this polyethylene-2,6-s7 tallate is completed, resulting in a copolymerized or mixed polyester. It may be. Suitable third components include compounds having a divalent ester-forming functional group, such as oxalic acid, adipic acid, phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,7-dicarboxylic acid, succinic acid, diphenyl ether dicarboxylic acid, "4c)'
) hrudtonic acid, or its lower furkyl ester, P
- oxycarboxylic acids such as oxybenzoic acid, P-oxyethoxybenzoic acid, or lower alkyl esters thereof;
Alternatively, compounds such as dihydric alcohols such as propylene glycol and trimethylene glycol may be mentioned. Polyethylene-2>6-naphthalate or its modified polymer has a terminal hydroxyl group and/or carboxyl group blocked by a monofunctional compound such as Yasui, Koki, benzoylbenzoic acid, benzyloxybenzoic acid, methoxypolyalkylene glycol, etc. Alternatively, it may be modified with a trifunctional or tetrafunctional ester-forming compound such as glycerin or pentaerythritol to the extent that a substantially linear copolymer can be obtained. good.

The surface roughness in the present invention is measured by a measurement method based on JIS 80601, and is 0.015 μm or more o, os
0μm or less, preferably 0.020μ or more, 0.0
It is 4 μm or less. Surface roughness Ra) is 0.01571
If it is less than +a, the slip property of the film will be insufficient and the rolled appearance will deteriorate. On the other hand, if it exceeds o, osoμ, the electrical properties, especially the dielectric strength, will deteriorate, which is not preferable.

Keep the surface roughness within the above range II! 1, for example, inert inorganic fine particles such as kaolin, talc, alumina, silica, titanium oxide, magnesium carbonate, calcium carbonate, etc. may be uniformly dispersed in the film, and the particle size and concentration can be adjusted. These inert inorganic fine particles can be added during polymerization, or a master l'c' of these fine particles can be made in advance and added during film extrusion, or a triblend can be added during film extrusion. There are several methods to do this, but the method is not limited to any one method.

Furthermore, in the present invention, the Young's modulus in the longitudinal direction of the film after biaxial stretching must be 600 ktt/wx2 or more. If the Young's modulus is lower than 5 Q Q kg/w*2, especially as the film becomes thinner as capacitors become smaller and lighter, it will become stiff and wrinkles may appear during vapor deposition.
During vapor deposition, the film stretches in the longitudinal direction, making it impossible to obtain a uniform product, and in extreme cases, it may break, which is undesirable.

In order to obtain a high-strength film with a Young's modulus of 600 #/2 or more in the longitudinal direction, it is usually necessary to increase the stretching ratio in the longitudinal direction in the case of polyethylene terephthalate, but as the film thickness decreases, it tends to break during film formation. is more likely to occur.

However, the 5PBN used in the present invention has a high Young's modulus even at the same stretching ratio as polyethylene terephthalate, and has a length of 3.
Young's modulus in the longitudinal direction is 600 under conditions of 5 times and 3.9 times horizontally.
kg/m".Furthermore, PBN has excellent stretching film forming properties, and despite its thin film thickness, it can be stretched at a high magnification, making it easy to obtain a high-strength film.As a method for biaxial stretching, For example, the so-called longitudinal-horizontal sequential stretching method in which an unstretched film is stretched in the longitudinal direction and then stretched in the transverse direction, the longitudinal-horizontal re-stretching method or the transverse-vertical re-transverse stretching method in which a normal biaxially stretched film is re-stretched. , simultaneous biaxial stretching method, etc.
In the present invention, any of these stretching methods can be employed.

Another feature of the present invention is that the heat shrinkage rate when heat treated at 150° C. for 30 minutes is 4 or less. In the case of polyethylene terephthalate, the dimensional stability of the high-strength film deteriorates, which greatly affects the handling characteristics of the film, that is, the yield during slitting, the yield during vapor deposition, and the yield during winding of capacitor elements. If the degree of crystallinity is extremely increased in order to maintain dimensional stability, not only will the Young's modulus in the longitudinal direction become low, but also the electrical properties at high temperatures will deteriorate. On the other hand, PBN used in the present invention has a small thermal shrinkage rate despite its high Young's modulus, and by adjusting the heat treatment temperature after stretching, it is possible to maintain
It is possible to reduce the heat shrinkage rate to 4% or less when heat treated at 50°C for 30 minutes.

Capacitors are generally manufactured using a winding method. That is, after alternately winding a biaxial PBN7 film and a metal foil such as aluminum, metallization is applied to the end face of the metal foil such as aluminum to provide an X pole, or metal evaporation of aluminum, zinc, etc. There is a method of winding the applied biaxially stretched PBN film and then applying metallicon to the end face of the vapor deposition part to provide an electrode, but the method is not particularly limited to this method.

However, compared to polyethylene terephthalate, PBN film generates extremely little oligomer, and when using the vapor deposition method, there is less soiling of the cooling can, which improves workability and gives the film an advantage in manufacturing capacitors using the vapor deposition method. A tree is standing.

〔Effect of the invention〕

Since the present invention uses a biaxially oriented PEN film with excellent heat resistance, the capacitor has excellent electrical characteristics at high temperatures. In addition, when producing capacitors, the insulating layer film has high strength, dimensional stability, and good slip properties, so it is easy to work with, and products can be obtained with high yield and yield.

〔Example〕

The present invention will be further explained below with reference to Examples.

In addition, various physical property values and characteristics in the present invention are measured and defined as follows.

(1) The Young's modulus film was cut into 10*n, [15mm] pieces, and pulled using an Instron-type universal tensile tester at a chuck distance of 100 mm, a tensile speed of 10 n/min, and a chart speed of 500 m/min. . Young's modulus is calculated from the tangent to the rising portion of the obtained load-elongation curve.

(2) Film surface roughness Ra) Measured according to JI8 B 0601. A chart (film surface roughness curve) was drawn using a stylus type surface roughness meter (SU FOOM3B) manufactured by Tokyo Seimitsu Co., Ltd. under the conditions of a needle radius of 2-1 and a load of 0.07fi. A part of measurement length L is extracted from the film surface roughness curve in the direction of its center line, X is the center line of this extracted part, Yllllb is the direction of vertical magnification, and the roughness curve is Y = f.
(When expressed as xi, the value given by the following formula (Ri:
μm) is defined as the film surface roughness.

In the present invention, the standard length is 0.25 m, 8 measurements are taken, and the average value of the 5 measurements excluding the 3 largest values is expressed as the average value.

(3) Marked lines are placed on the heat shrinkage rate measurement sample at approximately 30m+ intervals, and heat-treated for a certain period of time in a tension-free state (150℃
It is calculated from the change in sample length after 30 minutes) using the following formula.

(4) Dielectric breakdown voltage Measured by the method shown in JI8-0-2318.

(5) Electrical resistivity Measured by the method shown in ASTM-D-257.

(6) Amount of oligomer Extract the sample with 20 roform at a temperature of 25°C for 1 hour, add the absorbance of the extract at 245 m to the MP85000 multi-purpose self-recording spectrophotometer, and calculate the extracted oligomer using the pre-determined calibration curve. Find the quantity.

(7) Perform a 600cm DC voltage instantaneous withstand voltage test on the defective capacitor to determine the number of dielectric breakdowns.

Example 1 One pellet of PEN with an intrinsic viscosity of 0.60 and containing 0.2 wt of calcium carbonate with an average particle diameter of 1.2 μm was prepared.
It was dried at 70'C for 4 hours.

This PBN was melt-extruded according to a conventional method to a thickness of 40 μm.
3. Create an unstretched film and heat it in the machine direction at 120°C.
5 times, 1301:1 between lateral forces. The film was sequentially biaxially stretched by 3° and 9 times and further heat-set at 230°C to produce a 3 μm film.

This stretched film was applied to a vacuum evaporation machine to form a large number of aluminum evaporated films of about 400x thickness at wA2°, then rolled up, micro-slit, rolled so that the aluminum end faces were alternately on the outside, and metallikon was applied. I made a film capacitor.

Table 1 shows the electrical characteristics and defective rate of the obtained capacitor.

In this case, handling properties during vapor deposition, slitting, etc. were excellent, and high yields were obtained.

15 Examples 2 to 3 Comparative Examples 1 to 2 Same as Example 1, but when the amount of calcium carbonate added was 0.15 wt% with an average particle size of 1.2 μm, and an average particle size of 1.0 μm The amount of kaolin added is 0.3.0
．． Table 1 shows the results when 5.0.6 wt.

If R8 is smaller than 0.013 μm, wrinkles will appear during vapor deposition, wrinkles will occur during slitting and winding, and the defective rate will increase.

On the other hand, when Ra is larger than o or oso μm, the dielectric breakdown voltage decreases and the electrical resistivity at high temperatures decreases significantly.

Example 4 Comparative Example 3 The additives and the like are the same as in Example 1, but the longitudinal magnification is 4.
Table 2 shows a case where the longitudinal strength is increased by 5 times and a case where the longitudinal strength is slightly lowered by 3.0 times.

As Young's modulus increases, film stiffness increases,
Handling performance has improved and the defective rate has decreased. Also, P
Although EN is thin, it has excellent stretchability, so
A reinforced film with a Young's modulus of 800 kf/Ryu 2 was also easily obtained. Conversely, 1 Young's modulus of 600 kg/rm
When the value is less than 2, the handling properties deteriorate rapidly, and wrinkles occur during vapor deposition and slitting, resulting in a significant drop in the defective rate.

(Table 2 also shows the results of Example 1)
2 Example 5 Comparative Example 4 The same procedure as in Example 1 was carried out, except that the heat setting temperature was lowered to obtain a film having a heat shrinkage rate as shown in Table 3 and evaluated in the same manner.

When the heat shrinkage rate is greater than 4.0 inches, the defective rate increases,
As a result, the yield decreased significantly.

Table 3 Comparative Examples 5 to 6 Polyethylene terephthalate (abbreviated as PBT) containing calcium carbonate Q and 2vt H with an average particle diameter of 1.2μ was sequentially heated 3.6 times vertically and 3.9 times horizontally by a conventional method. Axial stretching was performed and the heat-setting temperature was changed to obtain films with 3μ wings with different heat shrinkage rates.

A capacitor was prepared using this film in the same manner as in Example 1, and the results of evaluation are shown in Table 4.

PR'Jll has a lower defect rate and a higher defect rate than PIaN. Furthermore, if the degree of crystallinity is increased in order to suppress the thermal shrinkage rate, the electrical properties will further deteriorate.

Furthermore, PET has a larger amount of beoligomer than PEN, and therefore the cooling can was contaminated during vapor deposition, which significantly reduced workability, but in the case of PEN, there was almost no staining of the cooling can.

Table 4

Claims (1)

[Claims] In a capacitor made of a laminate of an insulating layer and a metal layer made of a biaxially oriented polyethylene-2,6-naphthalate film, the surface roughness of the film is 0.015 μm or more and 0.050 μm or less, and the Young's modulus in the longitudinal direction is is 60
A capacitor having an insulating layer made of a biaxially oriented polyester film having a thermal shrinkage rate of 0 kg/mm^2 or more and a heat shrinkage rate of 4% or less when heat-treated at 150°C for 30 minutes.