JP2694652B2 - Vapor-deposited laminated film for capacitor and method for manufacturing film capacitor - Google Patents

Description

The present invention relates to a vapor-deposited laminated film for a capacitor and a method for producing a film capacitor.

[Prior Art] With recent miniaturization and weight reduction of various electric devices,
Since film capacitors are also becoming smaller and lighter, even thinner plastic films with higher dielectric constant are required for capacitors.

Among the plastic films currently put into practical use for capacitors, the thinnest polyethylene terephthalate film has a thickness of 1.5 μm, but such a thin film has a drawback that it is very difficult to handle. That is, when the thickness of the film is reduced to 1.5 μm, the shape-retaining force of the polyethylene terephthalate film itself is remarkably reduced, and the film is loosened, torn, or pinned during the capacitor manufacturing method such as vapor deposition, slitting, element winding and the like. Holes are likely to occur. As described above, when the film has an abnormality, it becomes necessary to correct the abnormality, which makes the work extremely difficult. Therefore, there is a strong demand for the development of a film that is thinner than this polyethylene terephthalate film and that is excellent in the shape retention of the film itself.

On the other hand, as a method for manufacturing such an ultra-thin film, different types of films are laminated in advance to form a thick film,
The method of peeling and using the ultrathin film from this is, for example, Japanese Patent Publication No. 43-15715, Japanese Patent Publication No. 58-132520, Japanese Patent Publication No. 58-136417, Japanese Patent Publication No. 57-176125, For example, in JP-A-58-5226, in JP-A-58-5226, a polyolefin and polyethylene terephthalate are co-extruded to form a laminated sheet, which is stretched and then the polyethylene terephthalate is peeled off. A method of making an ultrathin film is disclosed, suggesting that the ultrathin film may be vapor deposited.

However, in the method for producing an ultrathin film as described above, the ultrathin film is continuously formed from the support film,
It is extremely difficult to cleanly peel off to obtain a long ultrathin film, and there is a high risk of breaking or breaking during peeling, which is a major obstacle to practical use.

[Problems to be Solved by the Invention] The present invention is proposed to solve the problems of the conventional techniques as described above, and an object thereof is to provide a capacitor having a high practicability and capable of easily peeling an ultrathin film. It is intended to provide a vapor-deposited laminated film and a method of manufacturing a film capacitor having high workability.

[Means for Solving the Problems] The vapor-deposited laminated film for capacitors of the present invention has a thickness of 0.2 to 2.0 μm different from the support film, and an adhesive force of 0.1 to 2.0 g / on both sides of a plastic film serving as a support film.
cm plastic film is releasably attached, and metal is vapor-deposited on the surfaces of the first and second release films, the adhesive force of the first release film is the same as that of the second release film. It is characterized by being weakened in the range of 0.1 to 0.5 g / cm than the force of attachment.

In addition, the method for producing a film capacitor of the present invention uses the above vapor-deposited laminated film for capacitors, peels off the first peeling film having weak adhesive force, and after rotating the peeled vapor-deposited laminated film by 180 degrees. The second peeling film is peeled off from the rotated vapor-deposited laminated film, and the peeled first and second peeling films are laminated or wound.

Further, in the above manufacturing method, the first and second rollers having adhesiveness are used as means for peeling the first and second release films, and the adhesive force of the first release film is A, When the adhesive force of the release film is B, the adhesive force of the first roller is A ′, and the adhesive force of the second roller is B ′, the relationship of A <A ′ <B <B ′ is obtained. It is a feature.

In addition, as the plastic film used in the present invention, an organic polymer having a peeling property is prepared by a melt coextrusion method.
It can be obtained by layer-layer extrusion and then biaxially stretching uniaxially or sequentially or simultaneously. Typical organic polymers include polyolefins such as polyethylene, polypropylene, poly-4-methylpentene and polystyrene, polyethylene terephthalate, polybutylene terephthalate, polyethylene 2,6 naphthalate, polyethylene α, β bis (2chloro (phenoxy) ethane 4,4 ′ Polyester such as dicarboxylate), polyphenylene sulfide, polycarbonate, polyamide such as nylon 6, nylon 6,6, nylon 12, polyvinylidene fluoride, polyvinyl alcohol, polyacrylonitrile, polyether ether ketone, polyether ketone ketone, etc. is there. It may also contain these copolymers or other organic polymers. Known additives such as lubricants and plasticizers may be added to these copolymers.

Among the above organic polymers, especially 85 mol of repeating units such as polypropylene, polyethylene terephthalate, polyethylene 2,6 naphthalate, polyethylene α, β bis (2 chloro (phenoxy) ethane 4,4 ′ dicarboxylate), polyphenylene sulfide, etc. It is preferable to use a film thinned to have an unstretched film obtained by melt-coextruding a polymer containing 1% or more of the above components as a component, and stretching and arranging the unstretched film in biaxial directions to improve mechanical properties. .

In the present invention, since it does not peel off during laminated extrusion and must be peeled off after forming a vapor-deposited metal layer, the polymer combination should have a slight adhesive force during co-extrusion and should be peelable after metal vapor deposition. It is desirable that at least one of them is a polymer excellent in drawability.

The desired adhesiveness of the combination of various polymers to be melt-coextruded can be obtained by adjusting the polymer composition, coextrusion conditions, stretching conditions, heat treatment conditions and the like. Specifically, the adhesive force between the films is 0.1 to 2.0 g / cm, preferably in the range of 0.2 to 0.8 g / cm, and the difference in adhesive force between the two surfaces is 0.1.
It is desirable to be in the range of up to 0.5 g / cm. If the adhesive force is less than this range, it is likely to peel off during processing, contain an air layer, form pinholes, etc., and generate wrinkles during peeling, and peel off on both sides. On the contrary, if the adhesive force is larger than this range, the film is likely to be broken or torn during peeling.

As a method of adjusting the adhesive force between the films on both sides to the above range, 0.
A method of incorporating 001 to 1% by weight, more preferably 0.005 to 0.5% by weight of a non-particulate lubricant is adopted. Then, the difference in the content of the lubricant in the release film forms the difference in the adhesive force of the release film. The difference in the lubricant content in this case is
0.01 to 0.3% by weight is desirable.

The non-particulate lubricant is a substance having a melting point of 200 ° C. or lower even if it is a liquid or a solid at room temperature and imparts lubricity to the film. Specifically, aliphatic hydrocarbons, higher fatty acids or metal salts thereof, fatty acid amides,
Examples include fatty acid esters, fatty acid ketones, fatty alcohols, partial esters of fatty acids and polyhydric alcohols, nonionic surfactants, silicone oils, and fluorine surfactants.
The average particle size of 0.001 to
1 μm inorganic fine particles such as dry silica, wet silica,
0.01 ~ for zeolite, calcium carbonate, calcium phosphate, kaolin, kaolinite, clay, talc, acid or titanium, alumina, zirconia, aluminum hydroxide, etc.
If 0.5 wt% is contained, the effect of the non-particulate lubricant can be synergistically enhanced.

The film combination of the laminated film of the present invention can be adopted as long as the above conditions are satisfied, but specific preferable combinations include the following combinations.

A combination in which the support film is polypropylene and its copolymer, and the release film is any of polyester, polyamide, polyphenylene sulfide, and polyvinylidene fluoride.

The support film is polyester and its copolymer,
A combination of a release film made of either polyamide or polyphenylene sulfide.

A combination in which the supporting film is made of polyvinylidene fluoride or polymethacrylate blend and the release film is made of polyester or polyphenylene sulfide.

Further, the thickness of the laminated film of the present invention is 1.5 to 3 in total.
The thickness is preferably 0 μm. In this case, the thickness of the release film on both sides is 0.2-2.0 μm, more preferably 0.3-1.5 μm.
μm is desirable. If the release film is thinner than 0.2 μm, the release process may be performed or the film may be broken, which is not practical. Further, when the release film is thicker than 2.0 μm, it can be processed with a single film, so that there is no meaning as a laminated film as in the present invention.

The laminated film produced by the coextrusion method used in the present invention has T
Either the die method or the inflation method is possible. The part to be laminated can be in the adapter part, inside the die, or outside the die.

As the subsequent stretching method, either a tenter method or a tubular method can be applied. The stretching conditions are selected in consideration of the melting points, glass transition points, and stretching properties of the two or more polymers to be combined. Then, it is necessary that the polymer film to be the support film and the polymer film to be peeled off can be stretched at a predetermined temperature at a predetermined stretching ratio. In this case, it is preferable that the stretching temperature range and the stretching ratio range of the polymer film serving as the support film are wider than those of the polymer film to be peeled off, and the melting point and the glass transition point are low. This stretching is usually uniaxial or biaxial stretching. In the case of uniaxial stretching, the stretching ratio is generally 1.5 to 13 times, particularly preferably 3 to 9 times, and in the case of biaxial stretching, it is generally 2.5 to 8 in terms of area.
It is preferably 0 times, particularly 6 to 50 times.

[Operation] In the present invention using the laminated film produced under the above-mentioned conditions, the film to be peeled has a thickness of 0.2 to 2.0 μm.
Since it is easier to handle in the range of thin film thickness than the unit film in terms of rigidity and strength, the risk of causing wrinkles, pinholes, scratches, etc. is extremely low. When the first peeling film and the second peeling film are laminated and wound from the laminated film to form a capacitor, the peeling film is integrated with the supporting film, so that it is easier than handling the ultrathin film alone. There is an advantage that you can work. Especially after the first release film is removed 180
The degree rotation can be easily performed.

Since the adhesive force of the first release film is smaller than the adhesive force of the second release film, only the first release film can be reliably released in the first release step, and the second release film can be released. And the release films on both sides do not peel off at the same time.

Furthermore, since the capacitor can be manufactured by using only one roll of the vapor deposition laminated film as the material,
There is also an advantage that the number of rollers and the like can be reduced and the manufacturing equipment can be simplified.

Example An example of the present invention will be described with reference to the drawings.

First Example The following three types of raw materials (pellets) were prepared.

"PET raw material 1" ... polyethylene terephthalate in which 0.2% by weight of diethylene glycol is copolymerized. Melting point 258
° C. Calcium montanate 0.08% by weight, average particle size 0.05μ
0.15% by weight of dry silica.

"PPC raw material" ... Propylene with an ethylene content of 5.5% by weight
Ethylene random copolymer. Melting point 125 [deg.] C. 0.5% by weight stearamide, 0.4 kaolinite with an average particle size of 0.7 μm
Weight% included.

"PET raw material 2" ... polyethylene terephthalate in which 0.3% by weight of diethylene glycol is copolymerized. 257 melting point
° C. Silysyl serotinate 0.1% by weight, average particle size 0.05μ
0.2% by weight of dry silica of m.

The above three types of raw materials are fed to separate extruders, melt-extruded at 280 ° C, and the respective melts are merged in a T-shaped die to form a PET1 / PPC / PET2 three-layer structure, which is 250 ° C. It was wound around the cooling drum of No. 3 and cooled and solidified to obtain a three-layer laminated sheet. The PET layers on both sides were each 5 μm thick, and the central PPC layer was 120 μm thick.

After heating this sheet to 90 ℃, longitudinally 3.1 times, 1
The film was stretched 3.2 times in the axial direction at 00 ° C., heat-treated at 200 ° C. for 6 seconds while keeping the tension as it was, then slowly cooled to room temperature and wound up. The resulting film is PE on both sides.
The thickness of each T layer is 0.5 μm, and the thickness of the central PPC layer is 12 μm
Met.

Next, place this laminated film in a vacuum vapor deposition machine and
Aluminum having a thickness of 500 angstrom was vapor-deposited on both surfaces of the PET layer under the conditions of 10 ^-5 Torr and a vapor deposition rate of 30 m / min while forming a 2 mm wide margin at the same position on the front and back sides. FIG. 1 is a cross-sectional view showing the vapor-deposited laminated film of this example obtained in this manner, 1 being a supporting film (PPC layer), 2
Is a release film (PET layer), 3 is a vapor-deposited metal layer, and 4 is a margin.

When the vapor-deposited PET layer was continuously peeled from the vapor-deposited film thus obtained, the peeling force (adhesive force) of one (second peeling film) was 0.45 g / cm, and the other (first peeling film) was 0.3 It was g / cm.

Then, slit this vapor-deposited film to a width of 1 cm, and
A vapor-deposited laminated film roll having a width was obtained. Using one of the vapor deposition film rolls, a winding operation of a capacitor as shown in FIG. 2 was performed. That is, the vapor-deposited laminated film 6 is sent out from the vapor-deposited laminated film roll 5 and the adhesive force is 0.4 g
Through the first peeling roller 7 set to / cm, the adhesive force
The first release film of 0.3 g / cm was peeled off and attached to the large-diameter winding drum 8, and the remaining laminated film was applied to the 180-degree rotation roll 9 and rotated 180 degrees, and then the adhesive force was 0.5.
Through the second peeling roller 10 set to g / cm, the adhesive force is 0.
The second release film having a weight of 45 g / cm was peeled off, attached to the same winding drum 8 and wound up. The remaining support film from which the release films on both sides were peeled off was wound into a support film roll 11. FIG. 3 is a view showing the peeling and sticking portion of the first peeling film in FIG. 2, in which 12 is the first peeling film and 13 is the second peeling film. Further, FIG. 4 is a view showing a laminated state of the first and second release films 12 and 13.

When the peeling film winding operation by peeling and sticking as described above was continuously performed, no wrinkles were generated, film tearing at the time of peeling, cutting, and back surface peeling did not occur, and the multilayer capacitor element was efficiently manufactured. Was obtained. Then, both ends of this multilayer capacitor element were subjected to metallikon to form electrodes, which were cut in the radial direction to complete the multilayer capacitor.

On the other hand, as a comparative example, a capacitor was prototyped by vapor-depositing aluminum on a 2.0 μm PET film, and a characteristic test was conducted. The capacitor of the comparative example withstands 100 V, and the capacitance per unit volume is 800 PF / mm ³ . However, the capacitor of this example had a capacity of 12800PF / mm ^3, which was 16 times as high as that of the comparative example, and could withstand 100V.

Second Example Instead of PET in the first example, two kinds of polyphenylene sulfide (PPS) raw materials as shown below were prepared.

"PET raw material 1" ... Poly-P-phenylene sulfide composed of sodium sulfide and 1,4 dichlorobenzene with a melt viscosity of 2500 poise. Fine silica powder 0.1 with a melting point of 285 ° C and an average particle size of 0.7 μm
% By weight, 0.05% by weight calcium stearate.

"PPS raw material 2": Poly-P-phenylene sulfide composed of sodium sulfide and 1,4 dichlorobenzene with a melt viscosity of 2500 poise. Silica fine powder with melting point of 285 ℃ and average particle size of 0.7μm 0.03
% By weight, 0.02% by weight calcium stearate.

Using the above-mentioned two types of PPS raw materials and the PPC raw material of the first embodiment, melt coextrusion at 305 ° C. to form a three-layer structure of PPS1 / PPC / PPS2, and 4.0 times in the longitudinal direction at 98 ° C., 100 ° C. When stretched 3.5 times in the transverse direction, the resulting laminated film had PPS layers on both sides.
It was 1.0 μm, and the central PPC layer was 12 μm.

Aluminum vapor-deposited metal layers were formed on both surfaces of this laminated film in the same manner as in Example 1.

From the vapor-deposited laminated film thus obtained, vapor-deposited PP
When the S layer was continuously peeled off, the peeling force (adhesive force) on one side was
0.3 g / cm and the other was 0.6 g / cm. Depending on this peeling force, the adhesive force of the first and second peeling rollers is 0.4 g / cm,
When 0.7g / cm was set, and continuous peeling, sticking, and winding work were performed in the same manner as in the first embodiment, a capacitor was manufactured.
As in Example 1, excellent properties were confirmed.

[Advantage of the Invention] In the present invention, the adhesive force of the first and second release films is set to 0.
Since it was set differently in the range of 1 to 0.5 g / cm,
The first peeling film can be peeled surely when peeling
The second release film or the release films on both sides do not peel off. Due to this effect, it is possible to surely perform the work of peeling off the first peeling film and sticking it to the winding drum having a large diameter, and then peeling off the second peeling film and winding it on the same winding drum. Of.

Therefore, since a thinner plastic film can be used as the dielectric as compared with the conventional one, the size and weight of the capacitor can be dramatically reduced.

In addition, since work such as metal deposition, slitting, and 180-degree rotation can be performed in a laminated state with sufficient shape retention, the film is easy to handle and has excellent workability. Since a capacitor element can be manufactured by using the method, there is an advantage that the work process and equipment can be simplified.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a vapor-deposited laminated film for a capacitor in one embodiment of the present invention, FIG. 2 is a front view showing a winding process of the capacitor of the same embodiment, and FIG. 3 is a peeling film in FIG. FIG. 4 is an enlarged cross-sectional view showing the peeling and pasting portion, and FIG. 4 is a cross-sectional view showing the laminated state of the first and second peeling films. 1 ... Support film, 2 ... Peeling film, 3 ... Vapor-deposited metal layer, 4 ... Margin 5 ... Vapor-deposited laminated film roll, 6 ... Vapor-deposited laminated film 7 ... First peeling roller, 8 ... Winding Take drum, 9 …… 18
0 ° rotation roll 10 …… second peeling roller, 11 …… supporting film roll 12 …… first peeling film, 13 …… second peeling film

Claims (3)

(57) [Claims] 1. Two plastic films, which are different from the support film and serve as release films, having a thickness of 0.2 to 2.0 μm on both sides of the plastic film to be the support film,
A vapor-deposited laminated film for capacitors, which is releasably adhered within a range of from 0.1 to 2.0 g / cm and has a metal vapor-deposited on the surfaces of the first and second release films. A vapor-deposited laminated film for capacitors, wherein the adhesive strength is weakened in the range of 0.1 to 0.5 g / cm than the adhesive strength of the second release film. 2. A first peeling step of peeling a first peeling film having a weak adhesive force using the vapor-deposited laminated film for a capacitor according to claim 1 and a remaining vapor-deposited laminated film peeled off. It comprises a step of rotating 180 degrees, a second peeling step of peeling the second peeling film from the rotated vapor-deposited laminated film, and a step of laminating or winding the peeled first and second peeling films. A method of manufacturing a film capacitor, which is characterized in that 3. The first and second rollers having adhesiveness are used in the first and second peeling steps, and the adhesive force of the first peelable film is A, and the adhesive force of the second peelable film is B, the adhesive force of the first roller is A ', and the adhesive force of the second roller is B', the relationship of A <A '<B <B' is satisfied. The method for producing a film capacitor as described in the item 2.