Metallized film, manufacturing method thereof and film capacitor

Abstract

[Problem] The purpose of the present invention is to improve a metallized film. [Solution] A metallized film in which a hydrocarbon oil having a 10% evaporation temperature of 237 DEG C or more and a 90% evaporation temperature of 337 DEG C or less is used as a shielding oil or a post-treatment oil. When the hydrocarbon oil is used as the shielding oil, it is preferable that the contact angle of the hydrocarbon oil with respect to the dielectric film is 17.922.8 DEG. In addition, more preferably, the contact angle of the hydrocarbon oil with respect to the polypropylene film is 17.922.8 degrees.

Description

Technical Field

[0001] The present invention relates to a metallized film, a method for manufacturing the same, and a film capacitor using the metallized film. Background Art

[0002] When manufacturing a metallized film having a vapor deposition pattern consisting of vapor deposition areas and non-vapor deposition areas, the non-vapor deposition areas on the surface of the dielectric film are masked in advance and then metal is vapor deposited to form a desired vapor deposition pattern on the surface of the dielectric film.

[0003] As a masking method, an oil masking method using oil as a masking material can be mentioned. Metal is not vapor-deposited on the portion to which the masking oil is attached, so a vapor deposition pattern corresponding to the applied (attached) shape of the masking oil is formed on the surface of the dielectric thin film.

[0004] However, in Patent Documents 1 and 2, fluorinated oil (perfluoropolyether, etc.) is used as a masking oil. Fluorinated oil has good wettability to the film, so it can suppress the defect caused by the oil not being sufficiently attached to the part to be masked (deficiency: the defect that metal is deposited on the part where metal is not originally deposited). In addition, it has high thermal stability and is not easy to decompose and deteriorate when heated, so it evaporates stably and is not easy to cause the defect caused by the oil evaporating and scattering to unexpected parts during metal deposition, thereby masking the part where metal is originally to be deposited (unevenness: the defect that metal is not deposited on the part where metal is originally to be deposited or the amount of deposition is very small).

[0005] However, on the other hand, fluorine oil is decomposed by electron beams irradiated during metal vapor deposition in order to improve the adhesion between the dielectric film and the cooling roller, generating fluorine ions, which promotes the degradation of the vapor-deposited metal, thus becoming a major factor in reducing the reliability of capacitors. In addition, fluorine oil is composed of carbon fluoride, which may burden the environment, so it is one of the substances that are intended to be controlled.

[0006] Hydrocarbon oils are sometimes used as masking oils, but since evaporation is unstable, the amount of oil deposited on the dielectric film tends to vary, resulting in unevenness and defects occurring frequently.

[0007] In addition, the vapor-deposited metal deteriorates due to moisture absorption. Therefore, silicone oil is sometimes applied to the vapor-deposited surface as post-treatment oil (after oil) to form a protective film.

[0008] However, since silicone oil has the property of easily allowing water vapor to permeate, it cannot fully suppress moisture absorption of the deposited metal.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: Japanese Patent Application Laid-Open No. 63-7363

[0012] Patent Document 2: International Publication No. 2017 / 068758 Summary of the invention

[0013] Technical problem to be solved by the invention

[0014] The present invention aims to improve metallized films.

[0015] Technical solutions for solving technical problems

[0016] The metallized film is characterized in that a hydrocarbon oil having a 10% evaporation temperature of 237° C. or higher and a 90% evaporation temperature of 337° C. or lower is used as a masking oil or a post-treatment oil.

[0017] In addition, in the above-mentioned metallized film, the contact angle of the hydrocarbon oil relative to the dielectric film is preferably 17.9 to 22.8°. Alternatively, the contact angle of the hydrocarbon oil relative to the polypropylene film is preferably 17.9 to 22.8°.

[0018] The film capacitor of the present invention is characterized by using any of the above-mentioned metallized films.

[0019] The method for producing a metallized film of the present invention is characterized by comprising a step of evaporating and adhering a hydrocarbon oil.

[0020] Effects of the Invention

[0021] When a hydrocarbon oil having a 10% evaporation temperature of 237°C or higher and a 90% evaporation temperature of 337°C or lower is used as the masking oil, the influence on the degradation of the deposited metal and the environmental burden are small, and a metallized film with suppressed unevenness and defects can be obtained.

[0022] When a hydrocarbon oil having a 10% evaporation temperature of 237° C. or higher and a 90% evaporation temperature of 337° C. or lower is used as the post-treatment oil, moisture absorption of the vapor-deposited metal can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a diagram showing a vapor deposition pattern of a thin film capacitor according to one embodiment of the present invention.

[0024] Figure 2 It is a cross-sectional view of the main parts of the metallized film.

[0025] Figure 3 It is a cross-sectional view of the main part of the metallized film coated with post-treatment oil.

[0026] Figure 4 It is a graph which shows the result of the moisture resistance load test. DETAILED DESCRIPTION

[0027] Hereinafter, a film capacitor according to an embodiment of the present invention will be described. Figure 1 as well as Figure 2 The metallized film 1 shown. The metallized film 1 has a vapor deposition pattern consisting of a vapor deposition portion 3 and a non-vapor deposition portion 4 on the surface of a dielectric film 2. The vapor deposition portion 3 refers to a portion where a metal such as aluminum or zinc is vapor deposited. The non-vapor deposition portion 4 refers to a portion where no metal is vapor deposited. The non-vapor deposition portion 4 is, for example, an edge portion for dividing the vapor deposition portion. The vapor deposition portion 3 divided by the edge portion becomes, for example, a split electrode 5. The split electrodes are connected to each other through a fuse portion 6. Figure 1 This is a diagram after a portion of the metallized film 1 is cut out, and is actually continuous in the film feeding direction.

[0028] The dielectric film is a synthetic resin film. For example, it is a film made of any one of polypropylene, polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polyvinylidene fluoride, and cycloolefin polymer. In particular, a polypropylene film is preferred, and a biaxially stretched polypropylene film is more preferred. In addition, it is preferred to perform a corona treatment on the surface. The thickness of the film is not particularly limited, and is, for example, 2.5 μm.

[0029] Incidentally, the non-evaporation portion is formed by an oil shielding method. The shielding oil used in the oil shielding method is a hydrocarbon oil that satisfies at least the following condition 1. In addition, it is more preferred that the shielding oil is a hydrocarbon oil that satisfies both conditions 1 and 2. Furthermore, it is further preferred that the shielding oil is paraffin oil among hydrocarbon oils that satisfy both conditions 1 and 2.

[0030] [Condition 1] 10% evaporation temperature is 237°C or higher, 90% evaporation temperature is 337°C or lower.

[0031] If the 10% evaporation temperature is lower than 237°C, the masking oil evaporates easily and unevenness is likely to occur. On the other hand, if the 90% evaporation temperature is higher than 337°C, defects are likely to occur.

[0032] The evaporation temperature is a value measured by thermogravimetric analysis based on JIS K0129 (2005). Specifically, a masking oil as a sample is placed in an aluminum container (without a lid) of a thermogravimetric-differential thermal analyzer (DTG-60H: manufactured by Shimadzu Corporation), and then the temperature is raised from room temperature to 600°C at a rate of 10°C per minute, and the temperature at which the mass decreases by 10% and the temperature at which the mass decreases by 90% are measured.

[0033] [Condition 2] The contact angle relative to the dielectric film is 17.9 to 22.8°.

[0034] The “contact angle” is preferably a contact angle with respect to a polypropylene film, more preferably a contact angle with respect to a biaxially stretched polypropylene film, and further preferably a contact angle with respect to a corona-treated surface of a biaxially stretched polypropylene film.

[0035] If the contact angle is smaller than 17.9°, the masking oil tends to spread beyond the intended range, and unevenness tends to occur. If the contact angle is larger than 22.8°, it is difficult for the masking oil to adhere to the dielectric film, and defects tend to occur.

[0036] The contact angle is a value measured by the sessile drop method based on JIS R3257 (1999). Specifically, under the conditions of 25°C and 50% humidity, 3±0.5μL of liquid is dropped on the sample using a microsyringe and then left to stand. The drop is photographed after 1.5±0.1 seconds. The radius r and height h of the drop are calculated and substituted into the following formula to calculate the contact angle θ.

[0037]

[0038] The above-mentioned metallized film is manufactured as follows. First, masking oil is attached to the surface of the dielectric film, for example, by a flexographic printing method. Specifically, a relief plate having convex portions having substantially the same shape as the non-evaporation portion is prepared, and masking oil is attached to the relief plate. For example, the masking oil contained in an oil tank is first heated using a heat source such as a heater to evaporate the masking oil. Next, the evaporated masking oil is applied to a roller (to make it adhere: evaporation process). Thereafter, the roller is pressed against the relief plate. Then, the relief plate is pressed against the surface of the dielectric film to transfer the masking oil (to make it adhere). At this time, the masking oil attached to the convex portions of the relief plate is transferred, and a masking oil layer 7 is formed on the dielectric film (refer to Figure 2 ). On the other hand, the masking oil attached to the concave part of the relief is not transferred. Therefore, the shape of the masking oil layer 7 after the transfer becomes substantially the same as the convex part of the relief. It should be noted that as a method for attaching the masking oil, in addition to the flexographic printing method, a screen printing method, a gravure printing method, an offset printing method, a spray method, a die coating method, etc. can also be used.

[0039] Next, metal is vapor-deposited on the surface of the dielectric film to which the masking oil is transferred. For example, the vapor deposition is performed by vacuum vapor deposition. Specifically, the dielectric film is placed in a vacuum vapor deposition machine, and metal is vapor-deposited on the surface treated with corona discharge in such a way that the film resistance value reaches a specified value. The metal is heated by, for example, resistance heating. Metal is vapor-deposited on the portion to which the masking oil is not attached, forming a vapor-deposited portion. On the other hand, metal is not vapor-deposited on the portion to which the masking oil is attached, forming a non-vapor-deposited portion. In summary, a vapor-deposited pattern corresponding to the shape of the concave portion of the relief is formed.

[0040] The film capacitor of the present invention is manufactured by winding the metallized film having the above structure and forming metal-sprayed electrodes, for example, by metal spraying, at both ends in the axial direction. It should be noted that lamination may be used instead of winding.

[0041] Next, the results of comparative examination of metallized films produced using different masking oils will be described.

[0042] [Example 1]

[0043] A hydrocarbon oil (paraffin oil) having a 10% evaporation temperature of 237°C, a 90% evaporation temperature of 317°C, and a contact angle of 17.9° was used as the metallized film for masking oil.

[0044] [Example 2]

[0045] A hydrocarbon oil (paraffin oil) having a 10% evaporation temperature of 265°C, a 90% evaporation temperature of 337°C, and a contact angle of 22.8° was used as the metallized film for masking oil.

[0046] [Comparative Example 1]

[0047] A hydrocarbon oil (paraffin oil) having a 10% evaporation temperature of 215°C, a 90% evaporation temperature of 295°C, and a contact angle of 14.3° was used as the metallized film for masking oil.

[0048] [Comparative Example 2]

[0049] A hydrocarbon oil (paraffin oil) having a 10% evaporation temperature of 253°C, a 90% evaporation temperature of 358°C, and a contact angle of 27.4° was used as the metallized film for masking oil.

[0050] Each embodiment and each comparative example was manufactured under the same conditions except that the masking oil was different. That is, a biaxially stretched polypropylene film with a length of 8000 m and a thickness of 2.5 μm was used as a dielectric film, and the surface was subjected to corona treatment. Then, the masking oil was attached to the corona treated surface by flexographic printing, and then aluminum was evaporated to form a predetermined vapor deposition pattern. The vapor deposition pattern is shown in FIG. Figure 1 As shown, edge portions (non-evaporation-deposition portions 4 ) are provided in a lattice shape, and adjacent divided electrodes 5 are connected to each other via fuse portions 6 .

[0051] As one of the inspection items, the presence of unevenness (the defect that metal is not deposited or the amount of metal deposition is very small in the part where metal should be deposited) and defects (the defect that metal is deposited in the part where metal is not originally deposited) were confirmed. It should be noted that for unevenness, the presence of unevenness was visually confirmed at the initial position of 1500m with a microscope magnified 20 times. For defects, samples were taken from the initial, middle and final stages (N=30 each), magnified 40 times with a microscope, and compared with the limit sample to confirm the presence of defects.

[0052] In addition, as other inspection items, the width dimension A of the edge portion extending in the direction perpendicular to the film feeding direction, the width dimension B of the edge portion extending in the direction parallel to the film feeding direction, and the width dimension C of the fuse portion provided between the edge portions extending in the direction parallel to the film feeding direction were measured. With regard to the dimensional accuracy, samples (each N = 30) were taken from the initial, intermediate, and final stages, and the dimensions were measured by magnifying the sample by 40 times using a microscope, and it was confirmed whether the average value and standard deviation σ of each dimension were within the reference value in Table 1. It should be noted that the reference value refers to the dimensional accuracy obtained when fluorine oil having a 10% evaporation temperature of 235°C or higher, a 90% evaporation temperature of 335°C, and a contact angle of 17.9 to 22.8° is used as the masking oil (other conditions are the same as those of each embodiment and each comparative example).

[0053]

[0054] The inspection results are shown in Table 2. As shown in the table, the unevenness, defects, and dimensional accuracy are all equivalent to the reference in Examples 1 and 2. On the other hand, the unevenness in Comparative Example 1 is lower than the reference, and the defects and dimensional accuracy in Comparative Example 2 are lower than the reference.

[0055]

[0056] Thus, it can be seen that even with hydrocarbon oil, by determining the evaporation temperature and the contact angle with the dielectric film, a result comparable to that of using fluorinated oil can be obtained. It should be noted that fluorinated oil has the following problems: it is decomposed by the electron beam irradiated during metal vapor deposition in order to improve the adhesion between the dielectric film and the cooling roller, generating fluorine ions, which promotes the degradation of the vapor-deposited metal; and it is expensive. On the other hand, hydrocarbon oil is less likely to have such problems, and it is possible to manufacture inexpensive and highly reliable film capacitors.

[0057] It should be noted that the applicant has also confirmed that the film capacitors using fluorinated oil as the shielding oil and the film capacitors using the metallized films of Examples 1 and 2 have substantially the same lifespan (the rate of reduction in electrostatic capacitance when a voltage of 600 VDC is applied at 105°C).

[0058] Next, a metallized film using hydrocarbon oil as post-treatment oil is described. The post-treatment oil is oil applied to the vapor deposition surface (the surface where the vapor deposition portion 3 is formed) of the metallized film. The applied post-treatment oil forms a protective film 8 on the vapor deposition metal (vapor deposition portion 3) (see Figure 3). For example, the protective film 8 is formed by heating the post-treatment oil filled in the oil tank with a heat source such as a heater, evaporating the post-treatment oil, and attaching the evaporated post-treatment oil to the vapor deposition surface. That is, the application of the post-treatment oil is performed by vapor deposition in the same manner as the application of the masking oil. However, the post-treatment oil is directly applied, while the masking oil is indirectly applied via an intermediate such as a roller or a relief plate, which is different in this respect. It should be noted that in Figure 3 Although a boundary is drawn between the shielding oil layer 7 and the post-processing oil layer 8, they can be mixed together to make the boundary blurred.

[0059] The hydrocarbon oil used as the post-treatment oil satisfies the following condition 1.

[0060] [Condition 1] 10% evaporation temperature is 237°C or higher, 90% evaporation temperature is 337°C or lower.

[0061] If the 10% evaporation temperature is lower than 237°C, the post-treatment oil will evaporate easily and the protective film will not be stably formed. In addition, if the 90% evaporation temperature is higher than 337°C, when the post-treatment oil is heated to the evaporation temperature using a heat source such as a heater, the temperature difference between the position close to the heat source and the position far from the heat source will tend to become large. As a result, the amount of evaporated oil becomes unstable and the protective film will not be stably formed.

[0062] The evaporation temperature is a value measured by thermogravimetric analysis based on JIS K0129 (2005). Specifically, a masking oil as a sample is placed in an aluminum container (without a lid) of a thermogravimetric-differential thermal analyzer (DTG-60H: manufactured by Shimadzu Corporation), and then the temperature is raised from room temperature to 600°C at a rate of 10°C per minute, and the temperature at which the mass decreases by 10% and the temperature at which the mass decreases by 90% are measured.

[0063] The post-treatment oil is preferably paraffin oil among hydrocarbon oils. In addition, the same post-treatment oil as the above-mentioned shielding oil can also be used. That is, hydrocarbon oil (paraffin oil) that meets conditions 1 and 2 can also be used as shielding oil and post-treatment oil.

[0064] The post-treatment oil may be applied to the deposition surface by, in addition to the above-mentioned evaporation method, flexographic printing, screen printing, gravure printing, offset printing, spraying, die coating, and the like.

[0065] Next, the results of comparative examination of metallized films produced using different post-treatment oils will be described.

[0066] [Example 11]

[0067] A hydrocarbon oil (paraffin oil) having a 10% evaporation temperature of 237°C and a 90% evaporation temperature of 317°C was used as the metallized film of the post-treatment oil.

[0068] [Example 12]

[0069] A hydrocarbon oil (paraffin oil) having a 10% evaporation temperature of 265°C and a 90% evaporation temperature of 337°C was used as the metallized film of the post-treatment oil.

[0070] [Comparative Example 11]

[0071] A hydrocarbon oil (paraffin oil) having a 10% evaporation temperature of 215°C and a 90% evaporation temperature of 295°C was used as the metallized film of the post-treatment oil.

[0072] [Comparative Example 12]

[0073] A hydrocarbon oil (paraffin oil) having a 10% evaporation temperature of 253°C and a 90% evaporation temperature of 358°C was used as the metallized film of the post-treatment oil.

[0074] Each embodiment and each comparative example was manufactured under the same conditions except that the post-treatment oil was different. That is, a biaxially stretched polypropylene film with a length of 8000 m and a thickness of 2.5 μm was used as a dielectric film, and after the surface was corona treated, masking oil was attached to the corona treated surface by flexographic printing, and then aluminum was evaporated to form a predetermined vapor deposition pattern. The vapor deposition pattern is as shown in FIG. Figure 1 As shown, the edge portion (non-evaporation portion 4) is provided in a lattice shape, and the adjacent segmented electrodes 5 are connected to each other through the fuse portion 6. The post-processing oil filled in the oil tank is heated by a heater to evaporate the post-processing oil, thereby directly applying the post-processing oil to the entire evaporation surface.

[0075] As an inspection, check whether a stable protective film is formed. Specifically, first, by winding up each metallized film of Examples 11, 12, Comparative Examples 11, and 12, respectively, and forming a sprayed metal electrode, such as one formed by spraying metal, at both ends in the axial direction, a film capacitor with an electrostatic capacitance of 193μF is manufactured. Next, each film capacitor is placed in an environment of 115°C, and then a voltage of 600VDC is applied for 2000 hours. After 2000 hours, the winding of each film capacitor is unfolded, and 10m of the metallized film is taken out from each film capacitor, and the light transmittance of the vapor deposition part 3 in the film thickness direction of each metallized film is measured. The light transmittance is measured using a light emitter and a light receiver (optical fiber sensor FS-V21, FU-77V manufactured by Keyence Corporation).

[0076]

[0077] Table 3 shows the maximum and minimum values ​​of the measured light transmittance. If the vapor-deposited metal (evaporation section 3) deteriorates due to moisture, it becomes colorless and the light transmittance increases. Therefore, the greater the difference between the maximum and minimum values ​​of the light transmittance, the more it indicates that unevenness occurs in the formation of the protective film. However, as shown in Table 3, the difference between the maximum and minimum values ​​of the light transmittance of Example 11 and Example 12 is smaller than that of Comparative Examples 11 and 12, which shows that the protective film is formed with a substantially constant thickness, in other words, a stable protective film is formed.

[0078] Hydrocarbon oil has extremely low water vapor permeability. Therefore, when a stable protective film is formed, the vapor deposition section 3 can be prevented from coming into contact with water vapor, thereby suppressing the vapor deposition section 3 from deteriorating.

[0079] Figure 4 It is a chart showing the results of the moisture resistance load test. The test method is to place the film capacitor in an environment of 85°C and 85% humidity, then apply a voltage of 450VDC, and investigate the change in the capacitor capacitance after a specified time. It should be noted that "Example 11" in the figure represents a film capacitor using the metallized film of Example 11, "Comparative Example 13" represents a film capacitor using a metallized film that is the same as Example 11 except that silicone oil with a 10% evaporation temperature of 193°C and a 90% evaporation temperature of 264°C is used as post-treatment oil, and "Comparative Example 14" represents a film capacitor using a metallized film that is the same as Example 11 except that no post-treatment oil is applied.

[0080] As shown in the figure, the capacitor capacitance of Example 11 decreased by about 0.7% after about 3500 hours, whereas it decreased by about 3.1% in Comparative Example 13. Therefore, it can be seen that higher moisture resistance is obtained compared with the case where silicone oil is used as the post-treatment oil.

[0081] Description of Reference Numerals

[0082] 1: Metallized film; 2: Dielectric film; 3: Vapor-deposited part; 4: Non-vapor-deposited part; 5: Split electrode; 6: Fuse part; 7: Shielding oil layer; 8: Post-treatment oil layer (protective film); A: Width dimension of edge part; B: Width dimension of edge part; C: Width dimension of fuse part.

Claims

1. A metallized film, wherein a hydrocarbon oil having a 10% evaporation temperature of 237°C or higher and a 90% evaporation temperature of 337°C or lower is used as a masking oil or a post-treatment oil.

2. The metallized film according to claim 1, wherein: The contact angle of the hydrocarbon oil relative to the dielectric film is 17.9 to 22.8°.

3. The metallized film according to claim 1, wherein: The contact angle of the hydrocarbon oil relative to the polypropylene film is 17.9 to 22.8°.

4. A film capacitor using the metallized film according to any one of claims 1 to 3.

5. A method for manufacturing a metallized film, for manufacturing the metallized film according to claim 1, comprising: A step of evaporating and adhering the hydrocarbon oil.

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