JPH046084B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for manufacturing a capacitor element. [Prior Art] Japanese Patent Application Laid-Open No. 50-26873 discloses that unstretched films made of different or the same polymers are superimposed and then stretched, and that the laminated stretched film is vacuum-deposited on the surface of the film to be deposited. It is disclosed that the deposited film is peeled from the support film immediately before use. Furthermore, Japanese Patent Application Laid-Open No. 58-5226 discloses a combination in which a polyolefin film is used as a support and a polyester film is used as a film to be deposited. Furthermore, in Japanese Patent Application Laid-Open No. 60-257510, etc., after metal vapor deposition on polyphenylene sulfide film,
It is disclosed that the material is wound or laminated to form a capacitor element. [Problems to be solved by the invention] A method of forming a capacitor using polyvinylidene fluoride film or polyester film as a dielectric as disclosed in Japanese Patent Application Laid-open Nos. 50-26873 and 58-5226. However, the temperature, humidity, and frequency characteristics of capacitors are insufficient, and they cannot meet the recent demands for improved heat resistance. On the other hand, capacitors using polyphenylene sulfide film as a dielectric have excellent properties as described above, but
When trying to manufacture small, large-capacity capacitors by making the film ultra-thin, the conventional method described above has the disadvantage that the resulting capacitor elements have many insulation defects, resulting in a high rate of defective capacitors. It was hot. The present invention uses polyphenylene sulfide film, which has excellent temperature characteristics, humidity characteristics, and frequency characteristics, as a dielectric material. It is an object of the present invention to provide a method for manufacturing a capacitor element that can reduce the defective rate during operation. [Means for Solving the Problems] The present invention provides a support film made of polyolefin or polyester with a thickness of
A laminated film provided with a polyphenylene sulfide film of 0.2 to 1.5 μm is subjected to metal vapor deposition on the surface of the polyphenylene sulfide film, and then the metal-deposited polyphenylene sulfide film is peeled off from the laminated film. A method for forming a capacitor element using a polyphenylene sulfide film as a dielectric and a metal vapor deposited layer as an electrode by winding or laminating the peeled metal vapor deposited film, and The thickness is 5 times or more the thickness of the polyphenylene sulfide film, and the upper limit of the thickness of the support film Ts
(μm) relates to a method for manufacturing a capacitor element characterized in that Ts=37.5Tp+12.5 with respect to the thickness Tp (μm) of the polyphenylene sulfide film. The support film in the present invention refers to a non-oriented, uniaxially oriented or biaxially oriented film made of polyolefin or polyester, and its thickness is not particularly limited as long as it satisfies the above conditions;
5 to 50 μm is preferred. The polyolefins used in the present invention include low density polyethylene, medium density polyethylene, high density polyethylene, polypropylene, polybutene-1,
Examples include poly-4-methyl-pentene-1, copolymers and mixtures thereof, but propylene copolymers with a melting point of 100 to 150°C are preferred, and propylene/ethylene copolymers with a melting point of 110 to 150°C are preferred. Polymers are more preferred. Ethylene content 2.5
More preferred is ~8.0% by weight propylene/ethylene copolymer. This copolymer may be a multicomponent copolymer in which a third copolymer component (for example, butene-1, etc.) is further copolymerized to an extent smaller than the ethylene content. Further, other polyolefins may be mixed in an amount not exceeding 50% by weight. The polyester used in the present invention is a polymer or copolymer in which 50 mol% or more, preferably 75 mol% or more of the polymer chains are connected by ester bonds. It is preferable that the main glass transition point measured by DSC is in the range of 60 to 95°C. Further, it is preferable that the main peak of heating crystallization measured by DSC is 120° C. or higher. Such polyesters include polyethylene terephthalate and copolymers thereof, polybutylene terephthalate and copolymers thereof, polyethylene bis(2
Examples include -chlorophenoxy)ethane-4,4'-dicarboxylate and copolymers thereof. Various additives such as antioxidants, antistatic agents, lubricants, plasticizers, antiblocking agents, ultraviolet absorbers, and color pigments may be added to the support film. In the present invention, polyphenylene sulfide film (hereinafter sometimes abbreviated as PPS film) refers to a uniaxially or biaxially oriented film of a resin composition containing poly-p-phenylene sulfide as a main component. It is. The thickness of the film is in the range of 0.2 to 1.5 μm, but is more preferably in the range of 0.2 to 1.0 μm from the viewpoint of reducing the size of the capacitor. The average surface roughness Ra of the film is preferably in the range of 0.03 to 0.10 μm from the viewpoint of workability during winding or lamination and self-healing properties of the finished capacitor. In addition, the crystallinity by X-ray diffraction method is 25
% to 45% crystallized film is preferred. Furthermore, the degree of orientation OF obtained for the crystal peak at 2θ = 20 to 21μ by wide-angle X-ray diffraction is in the End direction and
It is preferable that the film is biaxially oriented in the range of 0.07 to 0.5 in the edge direction and 0.6 to 1.0 in the through direction. Here, a resin composition containing poly-p-phenylene sulfide as a main component (hereinafter sometimes abbreviated as PPS-based composition) refers to a resin composition containing 70% by weight of poly-p-phenylene sulfide. A composition containing the above. If the content of poly-p-phenylene sulfide is less than 70% by weight, the crystallinity, thermal transition temperature, etc. of the composition will be low, and the remaining content of less than 30% by weight in the composition will be poly-p-phenylene sulfide. It may also contain additives such as polymers other than phenylene sulfide, inorganic or organic fillers, lubricants, colorants, and ultraviolet absorbers. The melt viscosity of the resin composition is preferably in the range of 500 to 12,000 poise (more preferably 700 to 10,000 poise) at a temperature of 300°C and a shearing speed of 200 sec ^-1 from the viewpoint of film moldability. The melt viscosity of the resin composition is equal to the melt viscosity of the polyphenylene sulfide film finally obtained. In the present invention, poly-p-phenylene sulfide (hereinafter sometimes abbreviated as PPS) is
70 mol% or more (preferably 85 mol%) of repeating units
above) is the structural formula

〔Effect of the invention〕

As a result of the above configuration, the capacitor element manufactured by the method of the present invention has excellent heat resistance, temperature characteristics, and
Although the humidity and frequency characteristics remain the same and the capacitance is extremely small and large by using an ultra-thin film, there are few insulation defects in the dielectric material, and the insulation defect rate of capacitors made from it is extremely low. It has the characteristic of being highly reliable. In other words, according to the method of the present invention, an element having the same volume as a capacitor element conventionally made using a film with a thickness of 2 to 3 μm, but having a capacity several times to more than ten times higher, can be produced with a lower defect rate. can be manufactured without causing a significant increase in [Method for Measuring and Evaluating Characteristic Values] A method for measuring and evaluating characteristic values used in the description of the present invention will be explained. (1) Melting point of polymer 10 mg of the sample was placed in a DSC, and the temperature was raised at a rate of 20°C/min, and the melting point was defined as the temperature corresponding to the top of the endothermic peak accompanying melting. In addition, when there are two or more peaks, the temperature corresponds to the higher peak. (2) Glass transition point of polymer and main peak of heating crystallization Both were measured by DSC. (3) Insulation failure rate of capacitor elements A voltage of 80 V DC was applied per 1 μm of dielectric film thickness using an instantaneous application method to 100 capacitor elements, and the percentage of elements that suffered dielectric breakdown was defined as the insulation failure rate. It goes without saying that the smaller the number, the better. (4) Capacitance of capacitor element Using automatic capacitance bridge, 25
Capacitance was measured at 1kHz at ℃. (5) Temperature, frequency, and humidity characteristics of capacitor The above capacitance measurements were performed under various temperatures, frequencies, and humidity. (6) Soldering heat resistance of capacitors Initial capacitance
Evaluation was made based on the rate of change in capacity after immersion for seconds. The smaller the number, the better. (7) Degree of orientation (OF) The thickness of the sample is 1 mm, the width is 1 mm, and the stretching direction of the sample is aligned.
Laminate them into strips with a length of 10 mm (each film was fixed using a 5% amyl acetate solution of collodion during lamination), and the film was stacked along the film surface (End direction and Edge direction) or perpendicular to the film surface. A photograph of the plate was taken by injecting X-rays into the plate (Through direction). The X-ray generator is manufactured by Rigaku Denki, D
-3F type was used, and the X-ray source was Cu-Kα rays passed through a Ni filter at 40 kV and 20 mA. The distance between the sample and the film was 41 mm, and a multiple exposure method was used using Kodatsu non-screen type film. Next, the intensity of the (200) peak (corresponding to 2θ = 20 to 21°) on the plate photograph is calculated from φ = 0° (on the equator line) and φ =
Scan the densitometer in the radial direction from the center of the photograph at a position of 30 degrees, read the degree of blackening I, and define the degree of orientation (OF) of each sample as OF = I (φ = 30 degrees) / I (φ = 0 degrees). did. Here, I (φ=30°) is the maximum intensity of scanning in the φ=30° direction, and I (φ=0°) is the maximum intensity of scanning in the φ=0° direction. In addition, I (φ=0°) is the difference between φ=0° and φ=180°, and I (φ=30°) is the difference between φ30° and φ
The average value of =150° was used. In addition, the densitometer used is Sakura Microdensitometer Model PDM-5 Type A manufactured by Roku Konishi Photo Industry, and the measurement concentration range is 0.0 to 4.0D (minimum measurement area
4μ ² equivalent), slit width 1μ at optical system magnification of 100x,
Using a height of 10 μm and a film movement speed of 50 μm/
The chart speed in seconds is 1 mm/sec. [Example] Hereinafter, embodiments of the present invention will be described using Examples and Comparative Examples. Example 1 (1) Production of vapor-deposited laminated film Poly-p-phenylene sulfide consisting of 100% p-phenylene sulfide bonds has an average particle size.
A PPS-based composition in which 0.5% by weight of 0.4μm calcium carbonate fine powder is uniformly dispersed, and propylene.
Ethylene copolymer (melting point 135°C, hereinafter abbreviated as PEC) is supplied to separate extruders,
PPS is used in the outer two layers of the three-layer composite cap, which melts at 300℃ and has a structure where three flows merge inside the cap.
The system resin is supplied to the center layer, and the PEC is supplied to the center layer.
The three-layer laminated state of PPS/PEC/PPS was extruded into a sheet, wrapped around a cooling drum, and rapidly solidified to form an unstretched three-layer laminated sheet. This sheet is rolled between rolls at 98℃ in the longitudinal direction.
Stretched 4.1 times, then heated at 100℃ in the width direction in a tenter
Stretched 3.5 times laterally, further heat-treated at 250°C for 5 seconds in the same tenter, and then slowly cooled so that the thickness of the PPS layers on both surfaces was 0.7 μm, and the thickness of the center layer was 0.7 μm.
A three-layer laminated film with a PEC layer thickness of 15 μm was fabricated. The PPS in this surface layer is biaxially oriented, and the degree of orientation (OF) is 0.18 in the end direction, 0.19 in the edge direction,
The through direction was 0.88. This film roll was applied to a vacuum evaporation machine with a width of 500 mm, and aluminum was evaporated on both sides of the PPS layer to a thickness of 2Ω/□ on both sides. At this time, a margin portion was formed in the longitudinal direction at a ratio of 1.0 mm to the evaporated portion of 8.0 mm. Put the above vapor-deposited laminated film through a micro slitter, insert a blade in the center of the vapor-deposited part and the center of the margin part, and make a film width of 4.5 mm and an inner margin width of 0.5 mm.
mm tape and rolled it up in a laminated state. (2) Manufacture of capacitor elements A pair of vapor-deposited laminated film tapes is placed on a winder, and while peeling one vapor-deposited PPS film from each of the two tapes, two
The pieces were rolled together, pressed, and a capacitor element was made. Metallicon is sprayed on both end faces of this element to form external electrodes, lead wires are attached to this, and the outer electrode is coated with powder epoxy.
Evaluated as a 1.0 μF capacitor. (3) Evaluation The evaluation results of the obtained capacitors are shown in Table 1. Example 2 PPS/PET/PPS was prepared in the same manner as in Example 1, using polyethylene terephthalate (PET) instead of the propylene/ethylene copolymer in Example 1.
The three-layer laminated state was extruded into a sheet shape, wrapped around a cooling drum, and rapidly cooled and solidified to obtain an unstretched three-layer laminated sheet. This sheet was rolled between rolls at 96℃ in the longitudinal direction.
Stretched twice, then 3.4 times at 98℃ in the width direction in a tenter.
Double transverse stretching, further heat treatment at 250°C for 5 seconds in the same tenter, and further slow cooling until the thickness of both surface PPS layers is 0.7μm, and the thickness of the center PET layer is 0.7μm.
A 15μm three-layer laminated film was made. The PPS in this surface layer is biaxially oriented, and the degree of orientation (OF) is 0.21 in the end direction, 0.19 in the edge direction,
The through direction was 0.85. This film roll was subjected to the following steps of vacuum evaporation in the same manner as in Example 1, and a capacitor with a capacity of 1.0 μF was manufactured and evaluated. Table 1 shows the evaluation results of the obtained capacitors. Comparative Example 1 Only the PPS composition used in Example 1 was supplied to an extruder and melted at 300°C, extruded into a sheet, wound around a cooling drum, and rapidly cooled and solidified to obtain an unstretched sheet. This sheet was rolled between rolls at 98°C in the longitudinal direction.
Stretched twice, then 3.5 times at 100℃ in the width direction in a tenter.
The film was stretched horizontally twice, and further heat-treated for 5 seconds at 250° C. in the same tenter, and then slowly cooled to obtain a single-layer biaxially oriented PPS film with a thickness of 1.0 μm. This film roll was applied to a vacuum evaporation machine with a width of 500 mm, and aluminum was evaporated on both sides of the PPS layer to a thickness of 2Ω/□ on both sides. At this time, a margin portion was formed in the longitudinal direction at a ratio of 1.0 mm to the evaporated portion of 8.0 mm. This film was prone to breakage and wrinkles due to heat during vapor deposition, and had problems with its suitability for vapor deposition. The above-mentioned vapor-deposited film was passed through a micro-slitter, and blades were inserted into the center of the vapor-deposited part and the center of the margin part, and the film was wound up in a stacked state into a tape having a width of 4.5 mm and an inner margin width of 0.5 mm. Even with this slit, film breakage and wrinkles were likely to occur, and variations in margin width were noticeable. This pair of vapor-deposited film tapes are put on a winder,
I put the two pieces together, rolled them up, and then pressed them to make a capacitor element. Metallicon was sprayed on both sides of this element to form external electrodes, lead wires were attached to this, and the exterior was covered with powder epoxy.
It was evaluated as a capacitor with a capacitance of 1.0 μF. Table 1 shows the evaluation results of the obtained capacitors. Comparative Example 2 The vapor-deposited laminated film obtained in Example 1 was passed through a micro slitter, blades were inserted in the center of the vapor-deposited part and the center of the margin part, and the film was wound up into a tape with a width of 4.5 mm and an inner margin width of 0.5 mm. . At this time, immediately after the cutting part, the surface layer is deposited from the vapor-deposited laminated film.
The PPS film was peeled off and wound with a single layer of vapor-deposited PPS film. This pair of vapor-deposited film tapes are put on a winder,
I wound the two pieces together and pressed them again to make a capacitor element. Metallicon is sprayed on both end faces of this element to form external electrodes, lead wires are attached to this, and the outer electrode is coated with powder epoxy.
Evaluated as a 1.0 μF capacitor. Table 1 shows the evaluation results of the obtained capacitors. The capacitor elements manufactured by the method of the present invention from the above Examples 1 and 2 and Comparative Examples 1 and 2 can be manufactured by the conventional method of vapor deposition and winding of a single layer film (Comparative Example 1). It can be seen that the breakdown voltage defect rate is significantly lower than that in the case where three layers are laminated (Comparative Example 2). Examples 3-4, Comparative Examples 3-5 A three-layer laminate film of PPS/PEC/PPS was produced in the same manner as in Example 1. At that time, as shown in Table 2, various films with different thickness configurations of the PPS layer and the PEC layer were manufactured (the film thicknesses of both surface layers were the same). These film loams were subjected to the following steps of vacuum evaporation in the same manner as in Example 1, and the capacitance was 2.0 μF.
A capacitor was manufactured and evaluated. The evaluation results of the obtained capacitors are shown in Table 2. From Table 2, it can be seen that good productivity is achieved when the thickness of the support film at the center of the three-layer laminated film is in the range of 5 to 100 times the thickness of the PPS films on both surface layers. Ru.

【table】

【table】

Claims (1)

[Claims] 1 A support film made of polyolefin or polyester with a thickness of 0.2 to 1.5 μm on one or both sides.
of a laminated film provided with a polyphenylene sulfide film, metal vapor deposition is performed on the surface of the polyphenylene sulfide film, and then the metal vapor-deposited polyphenylene sulfide film is peeled off from the laminated film. A method for forming a capacitor element having a polyphenylene sulfide film as a dielectric and a metal vapor deposited layer as an electrode by winding or laminating metal vapor deposited films, and the thickness of the support film is within a range of It is 5 times or more the thickness of the polyphenylene sulfide film, and the upper limit of the thickness of the support film Ts (μm) is
Thickness Tp of the polyphenylene sulfide film
(μm), Ts=37.5Tp+12.5.