JPH0618151B2 - Metallized film capacitors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a capacitor, more specifically a dielectric layer (insulating layer).
The present invention relates to a laminated film capacitor in which a metal is vapor-deposited on a film to form a thin layer and then the film is wound or a film-like product having a dielectric layer provided on the surface of a metallized film is laminated.

(Prior Art) Generally, a capacitor is a method in which an organic polymer film such as a biaxially oriented polyethylene terephthalate film or a biaxially oriented polypropylene film and a metal foil such as an aluminum foil are superposed and wound, and the surface of the film is made of aluminum. A method of forming a vapor-deposited film of zinc, zinc or the like into a metallized film and then winding it, and further forming a metal film on both sides of the film to form a double-sided metallized film and providing a dielectric layer on the surface thereof. Are manufactured by a method of stacking.

Recently, with the demand for miniaturization of electric or electronic circuits,
The miniaturization of capacitors has also been strongly promoted, and the main materials thereof, such as polyethylene terephthalate film and polypropylene film, have also been made thinner, and the method of manufacturing capacitors is mainly made of metallized film. Such metallized film capacitors are deposited → slit → wound → metallikon process, or in the case of double-sided metallized film laminated capacitors, deposited → dielectric layer applied → wound → strip cut → metallikon → element cut It is manufactured through each process.

On the other hand, since the thermoplastic polyether ether ketone film has heat resistance, it is expected to be applied to capacitors and the like, as disclosed in JP-A-57-137116 and JP-A-61-37419. Is known for.

(Problems to be Solved by the Invention) As described above, a problem in manufacturing a metalized film capacitor is that the film such as a biaxially stretched polyethylene terephthalate film or a biaxially stretched polypropylene film to be a dielectric layer base film tends to be thinned. Accordingly, the film is likely to be wrinkled during the vapor deposition process, etc. When the wrinkle is generated, the adhesion between the cooling drum and the film in the vapor deposition process becomes insufficient and heat loss is reduced (insufficient cooling). In the prior art, wrinkling of the film was prevented by increasing the film tension in the longitudinal direction, but when the film becomes thinner, it tends to stretch when the tension is increased, and the appearance of the end surface of the film that has undergone vapor deposition and slits has a wrinkled appearance. It becomes flat and loses flatness, and the metal sprayed by the metallikon penetrates to the inside, which significantly reduces the insulation resistance between the capacitor terminals.

Further, although it is necessary to increase the stretching ratio in order to increase the rigidity (strengthen the stiffness) of the film that becomes the dielectric layer, high-stretching is not easy when the film is thin.

Also, if one pays attention to one film, the end face to be subjected to metallikon in the metallized film capacitor is a single-sided metallized film, and usually the film is curled with the metallized face inward, so that the metal particles and the metal film due to the metallikon are formed. Has a drawback that the contact area becomes smaller and the mechanical contact strength between the two becomes very weak. This is because the residual shrinkage stress inside the metal thin film is larger than the heat shrinkage stress of the film, so that the degree of curling increases as the film becomes thinner.

The problems of such conventional metallized film capacitors are
Even if a thermoplastic polyether ether con film is used, it is still unsolved.

It is an object of the present invention to provide a metallized film capacitor that does not have the above drawbacks.

(Means for Solving the Problems) The inventors of the present invention have conducted extensive studies as to a metallized film capacitor that strengthens electrical connection between a metal film on a film surface and an end-face electrode by a metallikon and obtains excellent electrical characteristics. It was found that the above properties can be satisfied by using a biaxially oriented polyetherketone resin film as a base film to be a dielectric layer, and adjusting its lateral heat shrinkage and longitudinal and lateral Young's modulus. However, the present invention has been reached.

That is, the present invention, the organic polymer film as a dielectric layer,
In a capacitor obtained by vapor-depositing a metal on the dielectric layer, the film forming the dielectric layer has a thermal shrinkage in the lateral direction at 150 ° C of 2 to 8%, and in the longitudinal and lateral directions. A metallized film capacitor characterized in that it is a biaxially oriented polyetherketone resin film having a -5 value of 11 kg / mm ² or more.

The thermoplastic polyetherketone resin in the present invention is a constitutional unit. Or Is a polymer composed of a single unit or other units. As other structural units, for example, Etc. In the structural units, A is a direct bond, oxygen, -SO 2 _-, - CO- or a divalent lower aliphatic hydrocarbon group, Q and Q 'may be different even in the same -CO - or -SO ₂ - and is, n represents 0
Or 1. These polymers are disclosed in JP-B-60-326.
42, Japanese Patent Publication No. 61-10486, Japanese Patent Laid-Open No. 5
No. 7-137116.

Thermoplastic polyetherketone resins include polyarylene polyether, polysulfone, and
Resins such as polyarylate, polyester, and polycarbonate may be blended, and stabilizers, antioxidants,
You may include additives, such as an ultraviolet absorber.

As mentioned above, the thermoplastic polyetherketone resin is known per se and can be produced by a method known per se.

The above thermoplastic polyetherketone resin has an apparent melt viscosity of 380 ° C. and an apparent shear rate of 1000 sec ⁻¹ , 500 poises to 10000 poises, and further 1000 poises to 500 poises.
Those in the range of 0 poise are preferable from the viewpoint of film forming property and film characteristics.

The biaxially oriented polyetherketone resin film used in the present invention needs to have a heat shrinkage ratio in the lateral direction of 2 to 8%, preferably 3 to 6% when heat-treated at 150 ° C. for 30 minutes. . When the heat shrinkage of the film is less than 2%, the metallized film is curled with the metal film inside and the base surface outside. As a result, when the metallikon is applied, the contact area between the metal particles and the metal film due to the metallikon becomes small, the electrical connection resistance increases, or partial electrical connection failure occurs, and the tan δ characteristic of the capacitor deteriorates.

On the other hand, when the heat shrinkage ratio of the base film exceeds 8%, the film, which is a metal film support, is largely deformed by heat when metallikon is applied, and the metal film is thermally deformed. As a result of the connection with the end face electrodes,
When a large current is instantaneously applied as in a charge / discharge test, the electrical connection is affected, and the tan δ characteristic of the capacitor deteriorates. Further, if the heat shrinkage exceeds 8%, the width shrinkage of the film in the vapor deposition step becomes large, and it becomes difficult to control the formation of a constant width margin.

That is, when the heat shrinkage ratio in the transverse direction when the film was heat-treated at 150 ° C for 30 minutes was adjusted to 2% to 8%, the metallized film did not curl, and the connection strength between the metal film and the end face electrode was large. No deterioration in electrical characteristics due to defects is observed.
This is because the residual shrinkage stress inside the metal thin film and the heat shrinkage stress of the film are balanced.

The means for adjusting the heat shrinkage in the transverse direction of the film within the above range can be achieved by appropriately adjusting the heat treatment temperature after longitudinal and transverse stretching. Another method is to further stretch (stretch) the film in the transverse direction by 5% to 30% in the tenter after the heat treatment. The adjustment of the heat shrinkability only by the heat treatment temperature increases not only the heat shrinkage in the horizontal direction but also the heat shrinkage rate in the vertical direction. As is known from Japanese Patent Publication No. Sho 60-30095, the increase in the heat shrinkage ratio in the longitudinal direction of the film deteriorates the tan δ characteristic in the laminated film capacitor.
Not preferable.

Furthermore, the biaxially oriented polyetherketone resin film used in the present invention has an F-5 value of 11 kg in both the longitudinal and transverse directions.
/ Mm ² or more, preferably 12 kg / mm ² or more, more preferably
It must be 13 kg / mm ² or more. Vertical F-
If the 5 value is lower than 11 kg / mm ² , downsizing of the capacitor,
As the film becomes thinner as the film becomes thinner, the waist becomes weaker (reduction in rigidity), so wrinkles may occur during vapor deposition, and if the film tension is increased to prevent wrinkles, the film stretches in the longitudinal direction and vapor deposition The end surface of the film after slitting is deformed (expanded and contracted) into a seaweed state and becomes non-flat, and the metallicon sprayed metal penetrates into the inside, which lowers the insulation resistance between the capacitor terminals, which is not preferable.

When the lateral F-5 value is less than 11 kg / mm ² , the lateral stiffness is weak and fine wrinkles occur in the vertical direction, causing heat loss due to poor contact with the cooling drum in the vapor deposition process. . At the time of heat pressing, voids are generated in the heat losing portion, which lowers the effective dielectric constant and causes large variations, which is not preferable.

In order to obtain a high-strengthened film having F-5 values of 11 kg / kg / mm ² or more in the longitudinal and transverse directions, it is usually necessary to increase the stretching ratio in the longitudinal and transverse directions in the case of polyethylene terephthalate. In such a manufacturing method, as the film thickness becomes thinner, breakage easily occurs during film formation. However, with a polyetherketone resin film, a higher F-5 value can be obtained even at a lower draw ratio than with a polyethylene terephthalate film, and the F-5 value in the longitudinal and lateral directions is 11 kg / which becomes mm ² can be easily obtained.

Examples of the biaxially stretching method include so-called longitudinal-transverse sequential stretching method in which an unstretched film is stretched in the longitudinal direction and then in the transverse direction, and longitudinal-transverse-re-longitudinal or transverse-direction in which a normal biaxially stretched film is re-stretched. There are longitudinal-re-transverse stretching method, simultaneous biaxial stretching method and the like, and any of these stretching methods can be adopted to obtain the film used in the present invention.

In addition, in order to obtain an appropriate surface roughness, inactive solid particles are usually added to the capacitor film.
If the draw ratio is increased in order to increase the −5 value, the problem may occur that the film is frequently cut due to the contained coarse particles and agglomerated particles. However,
Average particle size is 0.05 ~ 4μm, particle size ratio (major axis / minor axis) is 1.0
The content of spherical silica fine particles of ~ 1.2 is 0.01 ~ 3.0.
In the case where it is dispersed or contained in a thermoplastic polyetherketone resin alone or in a mixture with other inert solid particles so as to be a weight%, or an average particle diameter is 0.01 to 4 μm, f = V
/ D ³ [where V is the average volume (μm ³ ) of the particles, D is the average maximum particle size (μm) of the particles], and the volume shape factor (f) is 0.4 to π / 6. , The general formula R _X S _i
O2 _{-X / 2} (wherein R is a hydrocarbon group having 1 to 7 carbon atoms, X is 1 to
When the silicone resin fine particles represented by 1.2) are dispersed alone or mixed with other inert solid particles so as to have a content of 0.005 to 3.0% by weight and dispersed in the thermoplastic polyetherketone resin. , Spherical silica fine particles, silicone resin fine particles and polyetherketone resin have a high affinity, so that voids are less likely to occur around the particles when biaxial orientation is performed, and cutting of the film does not occur, resulting in electrical insulation. It is particularly preferable because a good film can be obtained.

In this case, it is preferable that the spherical silica fine particles are substantially spherical, have a sharp particle size distribution and are nearly monodisperse, and the manufacturing method thereof and others are not limited at all. Particularly, it is desirable that the relative standard deviation represented by the following formula is 0.5 or less.

For example, spherical silica particles are made of ethyl orthosilicate [Si
Hydrolysis of (OC ₂ H ₅ ) ₄ ] results in hydrous silica [Si
(OH) ₄ ] monodisperse spheres are prepared, and the hydrous silica monodisperse spheres are dehydrated to give silica-bonded [≡Si-O-Si].
It can be produced by three-dimensionally growing (≡) (Journal of the Chemical Society of Japan '81, No9, P.1503).

Si (OC ₂ H ₅ ) ₄ + 4H ₂ O → Si (OH) ₄ +4
C ₂ H ₅ OH ≡Si-OH + HO-Si≡ → ≡Si-O-Si≡ + H ₂ O On the other hand, the silicone resin fine particles are substantially spherical, and their flow distribution is sharp and close to monodisperse. Is preferable, and the manufacturing method thereof is not limited thereto. In particular, the viscosity distribution ratio (γ) represented by the following formula is 1
~ 1.4 is desirable.

The spherical silicone resin fine particles have the following formula (A) It has a composition represented by.

R in the above formula (A) is a hydrocarbon group having 1 to 7 carbon atoms, and for example, an alkyl group having 1 to 7 carbon atoms, a phenyl group or a tolyl group is preferable. The alkyl group having 1 to 7 carbon atoms may be linear or branched, and examples thereof include methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl, n-pentyl, n
-Heptyl and the like can be mentioned.

Of these, methyl and phenyl are preferable as R, and methyl is particularly preferable.

X in the above formula (A) is a number of 1 to 1.2. When x is 1 in the above formula (A), the above formula (A) has the following formula (A) -1 RSiO _1.5 (A) -1 [wherein the definition of R is the same as above]. Can be expressed as

The composition of the above formula (A) -1 has the following structural portion in the three-dimensional polymer chain structure of the silicone resin; It is derived from.

Further, when x is 1.2 in the above formula (A), the above formula (A) is represented by the following formula (A) -2 R _1.2 SiO _1.4 ... (A) -2 [wherein the definition of R is the same as above]. It can be represented by.

The composition of the above formula (A) -2 has the structure of the above (A) -1 0.8
It can be understood that it is composed of moles and 0.2 mole of a structure represented by the following formula (A) 'R ₂ SiO ... (A)' [where R is the same as the above].

The above formula (A) 'represents the following structural portion in the three-dimensional polymer chain of the silicone resin; Derived from.

As understood from the above description, the composition of the above formula (A) substantially consists of, for example, only the above formula (A) -1 structure, or the composition of the above formula (A) -1 and the above formula (A) -1 A)-
It can be seen that the structure of No. 2 is composed of coexisting structures in a state where they are randomly bonded at an appropriate ratio.

The spherical silicone resin particles preferably have the above formula (A)
In, x has a value between 1 and 1.1.

The silicone resin particles have, for example, the following formula: The trialkoxysilane represented by or a partial hydrolyzed condensate thereof can be produced by hydrolyzing and condensing in the presence of ammonia or an amine such as methylamine, dimethylamine or ethylenediamine with stirring. According to the above method using the above starting material, the silicone resin particles having the composition represented by the above formula (A) -1 can be produced.

According to the above method, the dialkoxysilane represented by the formula (A) is used together with the above trialkoxysilane.
Silicone resin particles having the composition represented by -2 can be produced.

Thus, when the particle size distribution is close to monodisperse and contains fine particles that do not aggregate, there is almost no film breakage during stretching, and the dielectric breakdown voltage can be maintained at a high level, with particularly good results. can get.

The biaxially oriented polyether Kent resin film used in the present invention has a thickness of 0.5 to 25 μm, further 1 to 12 μm, and especially 1.
It is preferably 5 to 6 μm.

The metallized film capacitor is manufactured by, for example, a winding method, that is, a metal film such as aluminum or zinc is vapor-deposited on a biaxially stretched polyetherketone resin film and then the metal film is wound, and a metallikon is applied to the end surface of the vapor deposition portion to form an electrode. Examples thereof include a method of providing, a laminating method, that is, a method of forming a metal layer on both surfaces of a biaxially stretched polyetherketone resin film, coating the surface with a dielectric layer, winding the metal layer, and cutting and stripping the metal layer. The capacitor of the present invention is not limited to any manufacturing.

The polyetherketone resin film has the advantages that the amount of oligomers generated is extremely smaller than that of the polyethylene terephthalate film, the cooling drum during vapor deposition is less contaminated, and the workability is improved. The superiority of using a polyetherketone resin film as a dielectric layer base in the production of the above is outstanding.

(Example) The present invention will be further described with reference to the following examples.

Various physical properties and characteristics in the present invention are measured and defined as follows.

(1) F-5 value The film is cut out into a sample width of 10 mm and a length of 15 cm, and between the chucks.
100 mm, tensile speed 100 mm / min, chart speed 500 mm
It was calculated by pulling the sample (film) with an Instron type universal tensile tester under the condition of / min and dividing the load at 5% elongation from the obtained load-elongation curve by the initial cross-sectional area.

(2) Thermal shrinkage rate Marked lines were put on the measurement sample at intervals of about 30 mm, and the change was calculated from the change in sample length after heat treatment (150 ° C x 30 minutes) in a heating oven for a certain time in a tension-free state by the following formula.

(3) Capacitance (C), dielectric loss tangent (tan δ) JIS C 5102
Of the measurement method.

Example 1 Thermoplastic polyether ether ketone (manufactured by ICI: Polyether Aker Ketone 380G) has an average particle size of 0.7 μm.
m, particle size ratio 1.05, relative standard deviation 0.15 spherical silica particles
Add 0.2% by weight, mix, and melt-extrude at 380 ° C with an extruder to make an unstretched film with a thickness of 22 μm,
Sequential stretching of 2.5 times at 160 ° C and 3.0 times at 160 ° C in the transverse direction, heat setting at 250 ° C, and 1. at 250 ° C in the transverse direction.
The film was stretched 15 times to form a 2.5 μm film.

This stretched film is about 20 mm wide and approximately thick by a vacuum vapor deposition machine.
After forming a large number of 400Å aluminum vapor-deposited films, they were wound, microslit and wound so that the aluminum end faces were alternately on the outside, and metallikon was applied to make a film capacitor.

Table 1 shows the physical properties of the obtained film and the tan δ measurement results of the capacitor. In this case, there was almost no wakame-shaped non-flat portion on the end face and there was no curl.

Examples 2-4, Comparative Examples 1-2 Similar to Example 1, but various experiments were performed by changing the transverse draw ratio after heat treatment. Table 1 shows the results when the lateral heat shrinkage was changed.

When the heat shrinkage in the lateral direction is smaller than 2%, tan δ increases. This is because the metallized film curls with the metal film on the inside, causing a poor electrical connection between the end face electrode and the metal film due to the metallikon.

On the other hand, if the heat shrinkage in the lateral direction exceeds 8%, the tan
There is an increase in δ. This is due to the effect of thermal deformation during metallikon.

Examples 5 to 6 and Comparative Example 3 A film was formed in the same manner as in Example 1 except that the longitudinal magnification was changed (the longitudinal F-5 value was different). At this time, the heat shrinkage ratio in the transverse direction was adjusted to be constant by changing the draw ratio in the transverse direction after the heat treatment. Table 2 shows the physical properties of the obtained film and the tan δ characteristics of the obtained capacitor. In addition, in Table 2,
The characteristics of Example 1 are also shown.

As shown in Table 2, if the F-5 value is less than 11 kg / mm ² , wrinkles will be generated in the vapor deposition process and the end face will lack a flat seaweed shape. Penetrates into the wound layer and tan δ rises. On the other hand, when the F-5 value in the vertical direction is 11 kg / mm ² or more, stable tan δ characteristics can be obtained.

Examples 7 to 8 and Comparative Example 4 A film was formed in the same manner as in Example 1 except that the lateral magnification was changed and the F-5 value in the lateral direction was different. However, the heat shrinkage in the transverse direction was adjusted to be constant by changing the draw ratio in the transverse direction after the heat treatment. Table 3 shows the physical properties of the film and the capacitance of the capacitor in this case. In addition, Table 3 also shows the characteristics of Example 1.

When the F-5 value in the lateral direction is less than 11 kg / mm ^{2, the} capacitance rapidly decreases. This is due to the formation of voids between the dielectric film and the metal film due to wrinkles in the vapor deposition process.

Example 9 Average particle size 0.8 μm, volume shape factor 0.50, particle size distribution ratio 1.2
The granular silicone resin particles were mixed in an amount of 0.2 wt% and a biaxially oriented film of 2.5 μm was prepared in the same manner as in Example 1. The lateral heat shrinkage of the obtained film is
3.0%, F-5 values in the vertical and horizontal directions are 12.0 and 15.5k, respectively.
It was g / mm ² . The tan δ was 0.0025, which was sufficiently durable as a capacitor element.

(Effects of the Invention) The capacitor of the present invention uses a biaxially oriented polyetherketone resin film for the dielectric layer, which has high strength and is adjusted so that the lateral heat shrinkage is balanced with the residual shrinkage stress inside the metal thin film. Therefore, there is no contact between the metal thin film and the metallikon end face electrode due to curling, and there is no internal infiltration of the metallikon spray metal due to unevenness due to end face extension, so that the manufacturing process can be performed uniformly, and the quality is highly stable. ing.
Then, a metallized film capacitor having excellent electrical characteristics can be obtained.

Claims (1)

[Claims] 1. A capacitor comprising an organic polymer film as a dielectric layer, and a metal being vapor-deposited on the dielectric layer, wherein the film forming the dielectric layer has a heat shrinkage factor of 2 at 150 ° C. in the lateral direction. A metallized film capacitor, which is a biaxially oriented polyetherketone resin film having a F-5 value of up to 8% and a longitudinal and lateral F-5 value of 11 kg / mm ² or more.