WO2020045482A1

WO2020045482A1 - Metal layer-integrated polypropylene film, film capacitor, and method for producing metal layer-integrated polypropylene film

Info

Publication number: WO2020045482A1
Application number: PCT/JP2019/033660
Authority: WO
Inventors: 義和藤城; 佳宗奥山; 中田　将裕; 和之日當
Original assignee: 王子ホールディングス株式会社
Priority date: 2018-08-29
Filing date: 2019-08-28
Publication date: 2020-03-05

Abstract

A metal layer-integrated polypropylene film which has a polypropylene film and a metal layer that is superposed on one surface or both surfaces of the polypropylene film, and which is configured such that if A is the thermal shrinkage of the polypropylene film in a first direction before superposition of the metal layer thereon and B is the thermal shrinkage of the metal layer-integrated polypropylene film in the first direction, the ratio of the thermal shrinkage B to the thermal shrinkage A, namely (thermal shrinkage B)/(thermal shrinkage A) is from 0.25 to 0.60 (inclusive).

Description

Metal layer integrated polypropylene film, film capacitor, and method for manufacturing metal layer integrated polypropylene film

The present invention (first and second present inventions) relates to a metal layer-integrated polypropylene film, a film capacitor, and a method for producing a metal layer-integrated polypropylene film.

The polypropylene film has excellent electric characteristics such as high withstand voltage and low dielectric loss characteristics, and also has high moisture resistance. Therefore, it is widely used in electronic devices and electric devices. Specifically, for example, it is used as a film used for a high-voltage capacitor; a filter capacitor or a smoothing capacitor of a power conversion circuit such as a converter or an inverter.

In particular, in recent years, polypropylene films have begun to be widely used as capacitors for inverter power supply devices for controlling drive motors of electric vehicles and hybrid vehicles. Inverter power supply capacitors used in automobiles and the like are required to have small size, light weight, high capacity, and high reliability over a wide temperature range (for example, -40 ° C to 90 ° C) over a long period of time.

Here, the dielectric loss means that a part of the electric energy added to the dielectric is lost as heat energy, and the dielectric loss tangent (hereinafter, also referred to as “tan δ”) is an index indicating the degree of the dielectric loss. . tan δ is defined by the ratio between the real part (resistance) and the imaginary part (reactance) of the complex impedance. The value of tan δ indicates that the larger the value, the larger the ratio of heat energy lost to the applied electric energy. When a capacitor is used for a long time, tan δ of the capacitor increases due to various causes. When tan δ increases, a large amount of heat may be generated during use as a capacitor, which may cause deterioration of reliability such as deterioration of characteristics. Therefore, there is a demand for a small increase in tan δ even after long-term use.

Patent Document 1 discloses a polypropylene film for a capacitor having a heat shrinkage in the length direction of 3.0% or less and a heat shrinkage in the width direction of 0% or more and 1.0% or less (claim). 1). If the thermal shrinkage in the length direction of the polypropylene film for capacitors exceeds 3.0%, wrinkles due to the heat received from the vapor-deposited metal at the time of vapor-deposition processing are likely to occur, and the dimensions are stable in high-temperature processes such as heat treatment during capacitor production. It is described that the capacitor lacks properties and cannot obtain stable capacitor characteristics (paragraph [0008]). If the thermal shrinkage in the width direction of the polypropylene film for a capacitor exceeds 1.0%, the end face of the capacitor element curls in a high-temperature process such as heat treatment during the production of the capacitor, and the contact resistance with the metallikon metal increases. It is described that stable dielectric characteristics cannot be obtained because the dielectric loss tangent of the capacitor is deteriorated (paragraph [0009]). In Patent Literature 1, the heat shrinkage of the capacitor polypropylene film before the vapor deposition step is set to be smaller than a predetermined value. Therefore, the heat shrinkage of the capacitor polypropylene film before the metal layer is laminated is reduced. Therefore, it is considered that the purpose is to obtain stable capacitor characteristics.

JP-A-11-273991

However, since a polypropylene film generally has a property of heat shrinking, as described in Patent Document 1, in order to reduce the heat shrinkage of the polypropylene film before laminating a metal layer, it is necessary to reduce the heat shrinkage as much as possible. It is necessary to select a raw material resin that can produce a polypropylene film that does not shrink. Therefore, there is a problem that the range of selection of the raw material resin is narrowed.
In addition, manufacturing conditions for obtaining a polypropylene film having a small heat shrinkage (a polypropylene film before laminating a metal layer) (for example, manufacturing conditions for a cast sheet (for example, melting temperature of raw material resin, casting temperature, etc.), casting It may be difficult to determine the conditions for the stretching treatment (eg, stretching temperature, stretching ratio, nip pressure, etc.) when the sheet is stretched to form a polypropylene film.
Furthermore, the selection of the raw material resin and the adjustment of the manufacturing conditions for reducing the heat shrinkage of the polypropylene film may sacrifice other characteristics (for example, withstand voltage characteristics).

The present invention (the first invention and the second invention) has been made in view of the above-described problems, and has as its object the room for selection of the material of the polypropylene film and the adjustment of the production conditions of the polypropylene film. An object of the present invention is to provide a metal layer-integrated polypropylene film capable of suppressing separation of a metallikon electrode while securing room. It is another object of the present invention (a first invention and a second invention) to provide a film capacitor having the metal layer-integrated polypropylene film. Further, an object of the present invention (the first present invention and the second present invention) is to provide a method for producing the metal layer integrated polypropylene film.

<First present invention>
The present inventors have intensively studied a metal layer-integrated polypropylene film. As a result, if the heat shrinkage of the metal layer-integrated polypropylene film after laminating the metal layer on the polypropylene film is significantly changed, as compared to the heat shrinkage of the polypropylene film before laminating the metal layer, It was found that the peeling of the metallikon electrode was suppressed when used as. As a reason, the present inventors have found that the heat shrinkage of the metal layer-integrated polypropylene film after laminating the metal layer on the polypropylene film is larger than the heat shrinkage of the polypropylene film before laminating the metal layer. If it decreases, the metal layer-integrated polypropylene film is less likely to thermally shrink even if it is further subjected to heat history, and the metal layer-integrated polypropylene film and metallikon electrode after long-term use as a capacitor. It is presumed that the relative displacement on the contact surface is suppressed. By adopting the following configuration, a metal layer-integrated polypropylene film capable of suppressing peeling of the metallikon electrode while securing room for selection of the material of the polypropylene film and adjustment of the production conditions of the polypropylene film. It has been found that the present invention can be provided, and the first invention has been completed.

The metal layer-integrated polypropylene film according to the first invention,
A polypropylene film,
A metal layer-integrated polypropylene film having a metal layer laminated on one side or both sides of the polypropylene film,
When the heat shrinkage in the first direction of the polypropylene film before laminating the metal layer is A, and the heat shrinkage in the first direction of the metal film integrated with the polypropylene is B, the heat shrinkage A and the heat shrinkage The heat shrinkage ratio [(heat shrinkage B) / (heat shrinkage A)] to the ratio B is 0.25 or more and 0.60 or less.

According to the configuration, since a metal layer is laminated on one or both surfaces of the polypropylene film, it can be used for a film capacitor in which the polypropylene film is a dielectric and the metal layer is an electrode.
Further, according to the configuration, since the heat shrinkage ratio is 0.60 or less, the polypropylene film shrinks relatively largely after the metal layer is stacked, as compared to before the metal layer is stacked. It can be said that. In other words, since the heat shrinkage ratio is 0.60 or less, the metal layer-integrated polypropylene film has already largely shrunk, and even when subjected to a heat history, it does not easily shrink any more. I have. As a result, relative displacement at the contact surface between the metal layer-integrated polypropylene film and the metallikon electrode due to long-term use after the capacitor is formed is suppressed, and peeling of the metallikon electrode can be suppressed.
Generally, a polypropylene film has a property of shrinking by heat. Therefore, by laminating the polypropylene film intentionally in the step of laminating the metal layer, the lamination of the metal layer is compared with before the lamination of the metal layer (before receiving heat when laminating the metal layer). It is relatively easy to reduce the heat shrinkage after the heat treatment (the heat shrinkage ratio is set to 0.60 or less). That is, in the first aspect of the present invention, by adjusting the conditions and the like when laminating the metal layers, the heat shrinkage ratio can be set to 0.60 or less, so that the selection range of the material resin is kept wide. be able to. For example, there is no limitation that a raw resin must be selected such that the heat shrinkage of a polypropylene film before laminating a metal layer is small as in Patent Document 1. Further, it is not necessary to adjust the production conditions of the polypropylene film so that the heat shrinkage of the polypropylene film before laminating the metal layer is reduced.
Further, since the heat shrinkage ratio is 0.25 or more, the dimensional stability is excellent.
As described above, according to the configuration, since the heat shrinkage ratio is 0.60 or less, it is possible to secure room for selection of the material of the polypropylene film and adjustment of the production conditions of the polypropylene film, and Since the rate ratio is 0.60 or less, it is possible to suppress the peeling of the metallikon electrode.

In addition, Patent Document 1 seems to be trying to suppress the curl of the end face of the capacitor element by reducing the thermal shrinkage in the width direction of the polypropylene film for the capacitor, thereby suppressing the peeling of the metallikon electrode. . That is, it seems that the polypropylene film for a capacitor is trying to suppress peeling due to shrinking in a direction away from the metallikon electrode surface.
On the other hand, in the first invention, the first direction is intended to be the MD direction (longitudinal direction, flow direction, vertical direction). According to the first aspect of the present invention, the wound metal layer-integrated polypropylene film is tightened by heat shrinkage, and the shearing separation at the contact surface between the metal layer-integrated polypropylene film and the metallikon electrode caused by the tightening is suppressed. Trying to.
As described above, although the first present invention and Patent Document 1 can have the same purpose in terms of suppressing the detachment of the metallikon electrode, the solution is completely different. That is, in the first aspect of the present invention, since the heat shrinkage ratio is set to 0.60 or less, shear separation at the contact surface between the metal layer-integrated polypropylene film and the metallikon electrode is suppressed. In Document 1, by reducing the thermal shrinkage in the width direction of the polypropylene film for a capacitor, the separation due to the polypropylene film for a capacitor shrinking in a direction away from the metallikon electrode surface is suppressed, and the solution is completely different.

金属 In the metal layer-integrated polypropylene film having the above-described configuration, it is preferable that the heat shrinkage A in the first direction of the polypropylene film before the metal layer is laminated is 2.0% or more and 10.0% or less.

If the thermal shrinkage A in the first direction of the polypropylene film before laminating the metal layer is 2.0% or more and 10.0% or less, there is room for selection of the material of the polypropylene film and adjustment of the production conditions of the polypropylene film. Can be secured more.

金属 The metal layer-integrated polypropylene film having the above structure is preferably used for a capacitor.

The metal layer-integrated polypropylene film can secure room for selection of the material of the polypropylene film and adjustment of the production conditions of the polypropylene film, and can suppress peeling of the metallikon electrode. Can be used for

金属 The metal layer-integrated polypropylene film having the above-described structure preferably has a dimensional change rate in the first direction at 120 ° C. of −0.40% or more.

When the dimensional change in the first direction at 120 ° C. of the metal layer-integrated polypropylene film is −0.40% or more, the dimensional change of the film becomes too large when used as a capacitor element at a high temperature. Can be suppressed. As a result, exfoliation of the metallikon electrode can be more suitably suppressed.

金属 In the metal layer-integrated polypropylene film having the above structure, the polypropylene film preferably has a plane orientation coefficient ΔP of 0.010 to 0.016.

(4) It is preferable that the plane orientation coefficient ΔP of the polypropylene film is within the above range, since the insulation breakdown at a high temperature and under a high voltage can be further reduced while appropriately controlling the heat shrinkage ratio.

ポリプロピレン It is preferable that the polypropylene film having the above-described configuration is biaxially stretched.

と When the polypropylene film is biaxially stretched, the heat shrinkage in the first direction of the polypropylene film tends to be larger than before the biaxial stretching. Therefore, when the polypropylene film is biaxially stretched, it is easy to obtain a metal-layer-integrated polypropylene film having the heat shrinkage ratio of 0.60 or less.

Further, the film capacitor according to the first aspect of the present invention is characterized in that the film capacitor includes the wound metal layer-integrated polypropylene film, or has a configuration in which a plurality of the metal layer-integrated polypropylene films are stacked. .

Further, the method for producing a metal layer-integrated polypropylene film according to the first aspect of the present invention,
Step A of preparing a polypropylene film,
A method for producing a metal layer-integrated polypropylene film, comprising: laminating a metal layer on one or both surfaces of the polypropylene film prepared in the step A to obtain a metal layer-integrated polypropylene film,
When the heat shrinkage in the first direction of the polypropylene film prepared in the step A is A, and the heat shrinkage B in the first direction of the metal layer-integrated polypropylene film obtained in the step B is A, the heat shrinkage A And a heat shrinkage ratio [(heat shrinkage B) / (heat shrinkage A)] of 0.25 to 0.60.

According to the configuration, since the raw material resin and the manufacturing condition that the heat shrinkage ratio is 0.25 or more and 0.60 or less may be adopted, there is room for material selection for manufacturing the metal layer integrated polypropylene film. And room for adjustment of manufacturing conditions. In addition, since the heat shrinkage ratio is 0.60 or less, it is possible to suppress peeling of the metallikon electrode when used as a capacitor.

前記 The polypropylene film prepared in the step A preferably has a heat shrinkage A in the first direction of 2.0% or more and 10.0% or less.

The first embodiment of the present invention has been described above.

<Second present invention>
The present inventors have intensively studied a metal layer-integrated polypropylene film. As a result, if the heat shrinkage of the metal layer-integrated polypropylene film is small, the relative displacement at the contact surface between the metal layer-integrated polypropylene film and the metallikon electrode due to long-term use after the capacitor is formed is suppressed. It has been found that peeling of the metallikon electrode is suppressed. Even if the heat shrinkage of the polypropylene film before the metal layer-integrated polypropylene film (the polypropylene film before the metal layer is laminated) is large, the heat shrinkage of the metal layer-integrated polypropylene film immediately before the capacitor is formed. It has been found that if the shrinkage ratio is small, peeling of the metallikon electrode can be suppressed. By adopting the following configuration, a metal layer-integrated polypropylene film capable of suppressing peeling of the metallikon electrode while securing room for selection of the material of the polypropylene film and adjustment of the production conditions of the polypropylene film. It has been found that the present invention can be provided, and the second invention has been completed.

The metal layer-integrated polypropylene film according to the second invention,
A polypropylene film,
A metal layer-integrated polypropylene film having a metal layer laminated on one side or both sides of the polypropylene film,
The heat shrinkage A in the first direction of the polypropylene film before laminating the metal layer is greater than 3.0%,
The heat shrinkage B in the first direction of the metal layer-integrated polypropylene film is 2.4% or less.

According to the configuration, since a metal layer is laminated on one or both surfaces of the polypropylene film, it can be used for a film capacitor in which the polypropylene film is a dielectric and the metal layer is an electrode.
In addition, according to the above configuration, since the heat shrinkage B in the first direction of the metal layer-integrated polypropylene film is 2.4% or less, the metal layer-integrated polypropylene film and the metallikon electrode can be used for a long time after forming a capacitor. Relative displacement on the contact surface with the contact is suppressed. As a result, exfoliation of the metallikon electrode can be suppressed.
In addition, since the thermal shrinkage A in the first direction of the polypropylene film before the metal layer is laminated is larger than 3.0%, there is room for selecting the material of the polypropylene film and adjusting the production conditions of the polypropylene film. In other words, there is little restriction that a raw material resin must be selected such that the heat shrinkage of the polypropylene film before the metal layer is laminated becomes small.
As described above, according to the above configuration, since the thermal shrinkage A in the first direction of the polypropylene film before the metal layer is laminated is larger than 3.0%, there is room for selection of the material of the polypropylene film and the manufacturing conditions of the polypropylene film. Since the room for adjustment can be secured, and the heat shrinkage B in the first direction of the metal layer-integrated polypropylene film is 2.4% or less, it is possible to suppress the metallikon electrode from peeling off.

In addition, Patent Document 1 seems to be trying to suppress the curl of the end face of the capacitor element by reducing the thermal shrinkage in the width direction of the polypropylene film for the capacitor, thereby suppressing the peeling of the metallikon electrode. . That is, it seems that the polypropylene film for a capacitor is trying to suppress peeling due to shrinking in a direction away from the metallikon electrode surface.
On the other hand, in the second invention, the first direction intends the MD direction (longitudinal direction, flow direction, vertical direction). According to the second aspect of the present invention, the wound metal layer-integrated polypropylene film is tightened by heat shrinkage, and the shearing separation at the contact surface between the metal layer-integrated polypropylene film and the metallikon electrode caused by the tightening is suppressed. Trying to.
As described above, although the purpose of the second present invention and Patent Document 1 can be common in terms of suppression of metallikon electrode peeling, the solution is completely different. That is, in the second invention, the metal layer-integrated polypropylene film has a heat shrinkage in the first direction (heat shrinkage intended in the MD direction) of 2.4% or less. On the other hand, in Patent Document 1, by reducing the thermal shrinkage in the width direction of the polypropylene film for the capacitor, the polypropylene film for the capacitor is reduced from the metallikon electrode surface, while suppressing the shear peeling at the contact surface with the electrode. Separation due to contraction in the direction away is suppressed, and the solution is completely different.

(4) In the metal layer-integrated polypropylene film having the above-described configuration, the heat shrinkage A in the first direction of the polypropylene film before laminating the metal layer is preferably greater than 3.5%.

(4) If the heat shrinkage A in the first direction of the polypropylene film before laminating the metal layer is larger than 3.5%, more room for selecting the material of the polypropylene film and adjusting the production conditions of the polypropylene film can be secured.

(4) It is preferable that the plane orientation coefficient ΔP of the polypropylene film is within the above-mentioned range, since the insulation breakdown at a high temperature and under a high voltage can be further reduced while appropriately controlling the heat shrinkage A and the heat shrinkage B.

と When the polypropylene film is biaxially stretched, the heat shrinkage in the first direction of the polypropylene film tends to be larger than before the biaxial stretching. Therefore, when the polypropylene film is biaxially stretched, it is easy to obtain one having a heat shrinkage in the first direction of more than 3.0%.

Further, the film capacitor according to the second aspect of the present invention has the configuration in which the metal layer-integrated polypropylene film is wound or a plurality of the metal layer-integrated polypropylene films are stacked. .

Further, the method for producing a metal layer-integrated polypropylene film according to the second invention,
A step A of preparing a polypropylene film having a heat shrinkage A in the first direction of more than 3.0%;
A step B of obtaining a metal layer-integrated polypropylene film by laminating a metal layer on one or both sides of the polypropylene film prepared in the step A,
The heat shrinkage B in the first direction of the metal layer-integrated polypropylene film obtained in the step B is 2.4% or less.

According to the above configuration, since it is sufficient to prepare a polypropylene film having a heat shrinkage A in the first direction of more than 3.0%, it is possible to secure a room for selecting a material of the polypropylene film and a room for adjusting production conditions of the polypropylene film. . Further, since the metal layer-integrated polypropylene film obtained in the step B has a heat shrinkage B in the first direction of 2.4% or less, it is possible to suppress the metallikon electrode from peeling off when used as a capacitor. Becomes

前記 The polypropylene film prepared in the step A preferably has a heat shrinkage A in the first direction of more than 3.5%.

The second embodiment of the present invention has been described above.

ADVANTAGE OF THE INVENTION According to this invention (1st this invention and 2nd this invention), the peeling of a metallikon electrode is suppressed, ensuring the room of the selection of the material of a polypropylene film, and the adjustment of the manufacturing conditions of a polypropylene film. It is possible to provide a metal layer-integrated polypropylene film capable of being used. Further, a film capacitor having the metal layer-integrated polypropylene film can be provided. Further, a method for producing the metal layer-integrated polypropylene film can be provided.

It is a typical perspective view for explaining the metal layer integral type polypropylene film produced as an example and a comparative example. It is a schematic diagram for demonstrating the manufacturing method of the metal layer integrated polypropylene film which concerns on an Example and a comparative example.

Hereinafter, embodiments of the present invention (the first present invention and the second present invention) will be described. However, the present invention (the first present invention and the second present invention) is not limited only to these embodiments.

表現 In this specification, the expressions “contain” and “contain” include the concepts of “contain”, “contain”, “consisting essentially of”, and “consisting of”.

において In this specification, “element”, “capacitor”, “capacitor element”, and “film capacitor” mean the same thing.

ポリプロピレン The polypropylene film according to the embodiment of the present invention (the first present invention and the second present invention) is not a microporous film, and thus does not have many pores. The polypropylene film according to the embodiment of the present invention (the first present invention and the second present invention) may be composed of two or more layers, but may be composed of a single layer. preferable.

<First embodiment of the present invention>
Hereinafter, the first embodiment of the present invention will be described.

The metal layer-integrated polypropylene film according to the first embodiment of the present invention (hereinafter, also referred to as “first embodiment”)
A polypropylene film,
A metal layer-integrated polypropylene film having a metal layer laminated on one side or both sides of the polypropylene film,
When the heat shrinkage in the first direction of the polypropylene film before laminating the metal layer is A, and the heat shrinkage in the first direction of the metal film integrated with the polypropylene is B, the heat shrinkage A and the heat shrinkage The ratio of the heat shrinkage to the ratio B [(heat shrinkage B) / (heat shrinkage A)] is 0.25 or more and 0.60 or less.

において In this specification, the first direction intends the MD direction (Machine Direction) of the polypropylene film. That is, in the first embodiment and a second embodiment described later, the first direction is preferably the MD direction. However, in the first embodiment and the second embodiment, the first direction is not limited to the MD direction, and any direction can be set as the first direction. Hereinafter, a case where the first direction is the MD direction will be described. In this specification, a direction orthogonal to the MD direction is a TD direction (Transverse Direction) (also referred to as a “width direction or a lateral direction”).

において In the present specification, the metallikon electrode refers to an external electrode provided on a side surface on which a metal layer-integrated polypropylene film is laminated and electrically connected to a metal layer as an internal electrode.

The metal-layer-integrated polypropylene film according to the first embodiment has a heat shrinkage ratio [(heat shrinkage B) / (heat shrinkage A)] of the heat shrinkage A and the heat shrinkage B of 0.60 or less. , Preferably 0.58 or less, more preferably 0.55 or less, further preferably 0.49 or less, and particularly preferably 0.48 or less. Since the heat shrinkage ratio is 0.60 or less, it can be said that the polypropylene film is relatively largely shrunk after the metal layer is stacked, as compared to before the metal layer is stacked. In other words, since the heat shrinkage ratio is 0.60 or less, the metal layer-integrated polypropylene film has already largely shrunk, and even when subjected to a heat history, it does not easily shrink any more. I have. As a result, relative displacement at the contact surface between the metal layer-integrated polypropylene film and the metallikon electrode due to long-term use after the capacitor is formed is suppressed, and peeling of the metallikon electrode can be suppressed.
Generally, a polypropylene film has a property of shrinking by heat. Therefore, by laminating the polypropylene film intentionally in the step of laminating the metal layer, the lamination of the metal layer is compared with before the lamination of the metal layer (before receiving heat when laminating the metal layer). It is relatively easy to reduce the heat shrinkage after the heat treatment (the heat shrinkage ratio is set to 0.60 or less). That is, in the first embodiment, the heat shrinkage ratio can be reduced to 0.60 or less by adjusting conditions and the like when laminating the metal layers. be able to. For example, there is no limitation that a raw resin must be selected such that the heat shrinkage of a polypropylene film before laminating a metal layer is small as in Patent Document 1. Further, it is not necessary to adjust the production conditions of the polypropylene film so that the heat shrinkage of the polypropylene film before laminating the metal layer is reduced.
Further, the heat shrinkage ratio is at least 0.25, preferably at least 0.28, more preferably at least 0.30, further preferably at least 0.40, particularly preferably at least 0.40. 45 or more. Since the heat shrinkage ratio is 0.25 or more, dimensional stability is excellent during heat treatment after winding the element.
Thus, according to the metal layer-integrated polypropylene film according to the first embodiment, since the heat shrinkage ratio is 0.60 or less, there is room for selection of the material of the polypropylene film and adjustment of the production conditions of the polypropylene film. Can be secured and the heat shrinkage ratio is 0.60 or less, so that the metallikon electrode can be prevented from peeling off. This point is clear from the embodiment.

<Method of measuring heat shrinkage B in first direction of metal layer integrated type polypropylene film>
A metal layer-integrated polypropylene film is cut into a rectangle having a width of 20 mm and a length of 130 mm to prepare a measurement sample. At this time, the first direction (MD direction in the first embodiment) is cut out as the length direction. Three measurement samples are prepared. In the case of the metal layer-integrated polypropylene film, when there is a portion where the metal layer is formed and a portion where the metal layer is not formed on the polypropylene film (when the metal layer is patterned on the polypropylene film), the measurement is performed. When cutting out a sample, a portion where the metal layer is formed over the entirety of a width of 20 mm and a length of 130 mm and a portion which is not a heavy edge is cut out. Next, a portion having a length of 100 mm of the measurement sample is measured with a ruler, and a mark is attached to the portion. Next, the three measurement samples are held in a hot air circulating thermostat at 120 ° C. with no load for 15 minutes. Then, it cools at room temperature (23 degreeC) and measures a dimension. The rate of change of the dimension after heating with respect to the dimension of 100 mm before heating at 120 ° C. is defined as the heat shrinkage B. Specifically, it is as follows.
(Thermal shrinkage B) = [[(dimension before heating) − (dimension after heating)] / (dimension before heating)] × 100 (%)
The measurement conditions other than those described here conform to “21. Dimensional change” of JIS C 2151: 2006.
More specifically, according to the method described in Examples.

The method for measuring the heat shrinkage A is the same as the method for measuring the heat shrinkage B, except that a polypropylene film before laminating a metal layer is used instead of the metal layer-integrated polypropylene film as the measurement sample. It is.

方法 The method of adjusting the heat shrinkage ratio is not particularly limited. For example, a material according to the purpose may be selected from various materials (such as a raw material resin), and the heat shrinkage B may be adjusted. That is, if the heat shrinkage ratio B is adjusted, the heat shrinkage ratio can be set to 0.25 or more and 0.60 or less, so that there is room for selecting materials for the polypropylene film.

The method for adjusting the heat shrinkage B is not particularly limited, but can be adjusted, for example, under conditions when a metal layer is laminated on a polypropylene film. Specific conditions for laminating the metal layer on the polypropylene film include, for example, (i) the temperature of the cooling roll, (ii) the temperature of the evaporation source, and (iii) the thickness of the metal layer.
Usually, the temperature of the cooling roll is often set low to suppress the heat loss of the polypropylene film, but if set to a high value, the polypropylene film can be largely thermally shrunk when the metal layer is laminated, There is a tendency that the heat shrinkage B of the obtained metal layer integrated type polypropylene film can be reduced. If the heat shrinkage B can be reduced, the shrinkage ratio can be easily reduced to 0.6 or less.
If the temperature of the evaporation source is set to be higher, the polypropylene film can be largely thermally shrunk when the metal layers are laminated, and the thermal shrinkage B of the obtained metal layer-integrated polypropylene film tends to be reduced. If the heat shrinkage B can be reduced, the shrinkage ratio can be easily reduced to 0.6 or less.
The thicker the metal layer, the longer it will be exposed to heat for lamination of the metal layer. Therefore, if the thickness is set to be large, the polypropylene film can be greatly shrunk by being exposed to heat for a long time during lamination of the metal layer, and the heat shrinkage B of the obtained metal layer integrated polypropylene film can be reduced. Tend to be able to. If the heat shrinkage B can be reduced, the shrinkage ratio can be easily reduced to 0.6 or less.

の他 Another example of the method of adjusting the heat shrinkage B is a method of laminating a metal layer on a polypropylene film and then performing a post-heating treatment. By performing the post-heating treatment, the metal layer-integrated polypropylene film before becoming a product can be thermally shrunk, and as a result, the heat shrinkage B of the metal layer-integrated polypropylene film as a product can be reduced. . If the heat shrinkage B can be reduced, the shrinkage ratio can be easily reduced to 0.6 or less.

熱 The heat shrinkage B is preferably 2.4% or less, more preferably 2.3% or less, still more preferably 2.2% or less, and particularly preferably 2.1% or less. When the heat shrinkage B is 2.4% or less, the relative displacement of the contact surface between the metal layer-integrated polypropylene film and the metallikon electrode due to long-term use after forming a capacitor is further suppressed. As a result, exfoliation of the metallikon electrode can be further suppressed. This point is clear from the embodiment. The heat shrinkage B is, for example, 0.5% or more, 0.8% or more, 1.0% or more. When the heat shrinkage B is 0.5% or more, the element is suitably wound and fastened during heat treatment after winding the element. As a result, voids between the films are removed, and the shape is stabilized. Also, the withstand voltage can be improved.

The heat shrinkage A (heat shrinkage in the first direction of the polypropylene film before laminating the metal layer) is preferably 2.0% or more, more preferably 3.1% or more, and more preferably 3.5% or more. It is preferably at least 4.0%. When the heat shrinkage factor A is 2.0% or more, there is more room for selecting materials for the polypropylene film and for adjusting the production conditions of the polypropylene film. That is, there is little restriction that a raw material resin must be selected such that the heat shrinkage (heat shrinkage A) of the polypropylene film before the metal layer is laminated becomes small. The upper limit of the heat shrinkage A is not particularly limited, but is, for example, 9.0% or less, 8.0% or less, 7.5% or less from the viewpoint of production of the polypropylene film.

As described above, in the first embodiment, it is preferable to use a polypropylene film having a heat shrinkage A of 2.0% or more as the polypropylene film. That is, there is no need to produce a polypropylene film having a small heat shrinkage A. Therefore, room for selecting a material for the polypropylene film is secured. Therefore, it is relatively easy to obtain a polypropylene film having the heat shrinkage A of 2.0% or more, and it may be selected from various materials (such as raw resin).

The thickness of the metal layer-integrated polypropylene film is preferably at least 0.8 μm, more preferably at least 1.2 μm, further preferably at least 1.5 μm, particularly preferably at least 2.0 μm. The thickness of the polypropylene film is preferably 3.5 μm or less, more preferably 3.0 μm or less, further preferably 2.9 μm or less, and particularly preferably 2.8 μm or less.

厚 The thickness of the metal layer-integrated polypropylene film refers to a value measured according to JIS-C2330, except that the thickness is measured at 100 ± 10 kPa using a paper thickness measuring device MEI-11 manufactured by Citizen Seimitsu.

In the metal layer-integrated polypropylene film, the dimensional change in the first direction at 120 ° C. is preferably −0.40% or more, more preferably −0.30% or more, and still more preferably −0.26%. That is all. When the dimensional change in the first direction at 120 ° C. is −0.40% or more, it is possible to prevent the dimensional change of the film from becoming too large when used as a capacitor element at a high temperature. As a result, exfoliation of the metallikon electrode can be more suitably suppressed. The dimensional change in the first direction at 120 ° C. is preferably 0.30% or less, more preferably 0% or less, further preferably -0.01% or less, and particularly preferably -0.05% or less.
In the first embodiment, the dimensional change rate in the first direction at 120 ° C. can be controlled by the temperature of the evaporation source, the thickness of the metal layer, and the like. For example, when the first direction is the MD direction, the MD dimensional change rate tends to increase in the minus direction as the temperature of the evaporation source is lower. For example, when the first direction is the MD direction, the MD dimension change rate tends to increase in the minus direction as the thickness of the metal layer increases (that is, the MD dimension change rate value is lower). Tend to be).
The dimensional change in the first direction at 120 ° C. is a value measured by a TMA method, and more specifically, according to the method described in Examples.

ポリプロピレン Hereinafter, a description will be given of a polypropylene film included in a metal layer-integrated polypropylene film as a product after a metal layer is laminated. That is, in the following, before lamination of the metal layer, or after lamination of the metal layer, without explicitly specifying, when referred to as `` polypropylene film '', unless otherwise specified, This will be described as meaning a polypropylene film after a metal layer is laminated.

The thickness of the polypropylene film is preferably 0.8 μm or more, more preferably 1.2 μm or more, further preferably 1.5 μm or more, and particularly preferably 2.0 μm or more. The thickness of the polypropylene film is preferably 3.5 μm or less, more preferably 3.0 μm or less, further preferably 2.9 μm or less, and particularly preferably 2.8 μm or less.

When the thickness of the polypropylene film is 3.0 μm or less, the capacitance per unit volume of the capacitor element can be increased, so that the polypropylene film can be suitably used for a capacitor. Further, from the viewpoint of film formation stability of the film and from the viewpoint of suppressing the heat shrinkage ratio B from increasing (from the viewpoint of suppressing the shrinkage ratio from exceeding 0.6), the thickness of the polypropylene film is reduced. The height can be 0.8 μm or more.
This will be described in detail below.
The smaller the thickness of the polypropylene film, the larger the capacitance per unit volume. More specifically, the capacitance C is expressed as follows using the dielectric constant ε, the electrode area S, and the dielectric thickness d (the thickness d of the polypropylene film).
C = εS / d
Here, in the case of a film capacitor, the thickness of the electrode is three orders of magnitude or more thinner than the thickness of the polypropylene film (dielectric). Therefore, when the volume of the electrode is ignored, the volume V of the capacitor is expressed as follows. Is done.
V = Sd
Therefore, from the above two equations, the capacitance per unit volume C / V is expressed as follows.
C / V = ε / d ²
As can be seen from the above equation, the capacitance per unit volume (C / V) is inversely proportional to the square of the thickness of the polypropylene film. The dielectric constant ε is determined by the material used. Then, it is understood that unless the material is changed, the capacitance per unit volume (C / V) cannot be improved except by reducing the thickness.
The electrode area does not affect the capacitance per unit volume (C / V). This will be described below.
It is assumed that a capacitor is manufactured by winding films of the same material and the same thickness. For example, it is assumed that the number of turns (the number of turns) is increased and the coil is wound ten times longer (the electrode area is ten times larger). Then, the capacitance increases ten times, but the volume also increases ten times, so that the capacitance per unit volume (C / V) does not change even if the electrode area changes.
The above description is idealized for ease of understanding. That is, in actuality, for example, a small gap may exist between the films, or there may be a fringe effect at an electrode end. / V) in some cases. However, it can be understood that, in general, the capacitance per unit volume (C / V) is determined by the thickness of the polypropylene film.
From the above, it is preferable that the thickness of the polypropylene film be as thin as possible within a range where the withstand voltage is secured. Therefore, the thickness of the polypropylene film is preferably 3.0 μm or less.
On the other hand, as the thickness of the polypropylene film decreases, the heat shrinkage B tends to increase. As the heat shrinkage B increases, the shrinkage ratio also increases. Therefore, if the thickness is too small, the risk of the metallikon electrode peeling off when the capacitor is used for a long time increases. Therefore, it is preferable that the thickness of the polypropylene film is 0.8 μm or more.

In the present invention (the first present invention and the second present invention) and the thickness of the polypropylene film in the present specification, the thickness of the metal layer (film resistance) is determined from the thickness of the metal layer-integrated polypropylene film. (The thickness of the metal layer converted from the above).
The thickness of the metal layer in the metal layer-integrated polypropylene film is preferably from 0.1 to 10 nm. When the thickness of the metal layer is 0.1 to 10 nm, the thickness of the polypropylene film integrated with the metal layer and the thickness of the polypropylene film show substantially the same value in the measurement method described in this example.

The polypropylene film may be a biaxially stretched film, a uniaxially stretched film, or a non-stretched film. Among them, a biaxially stretched film is preferable. When the polypropylene film is biaxially stretched, the heat shrinkage in the first direction of the polypropylene film tends to be larger than before the biaxial stretching. Therefore, when the polypropylene film is biaxially stretched, it is easy to obtain a metal-layer-integrated polypropylene film having the heat shrinkage ratio of 0.60 or less.

The polypropylene film preferably has a plane orientation coefficient ΔP of from 0.010 to 0.016, more preferably from 0.011 to 0.0155, even more preferably from 0.0115 to 0.015. .

<Plane orientation coefficient ΔP>
In the present specification, the “plane orientation coefficient ΔP” refers to a plane orientation coefficient ΔP calculated from the values of the birefringence values ΔNyz and ΔNxz in the thickness direction of the polypropylene film obtained by optical birefringence measurement (where ΔP = (ΔNyz + ΔNxz) / 2).
In the present specification, the “birefringence value ΔNyz” in the thickness direction of the polypropylene film refers to the birefringence value ΔNyz in the thickness direction obtained by optical birefringence measurement. More specifically, the principal axes in the in-plane direction of the film are x-axis and y-axis, and the thickness direction (normal direction to the in-plane direction) of the film is z-axis. Assuming that the slow axis in the higher direction is the x-axis, the value obtained by subtracting the three-dimensional refractive index in the z-axis direction from the three-dimensional refractive index in the y-axis direction is the birefringence value ΔNyz.

In the present specification, the “birefringence value ΔNxz” in the thickness direction of the polypropylene film refers to the birefringence value ΔNxz in the thickness direction obtained by optical birefringence measurement, and more specifically, the x-axis The value obtained by subtracting the three-dimensional refractive index in the z-axis direction from the three-dimensional refractive index in the (slow axis) direction is the birefringence value ΔNxz.

In the first embodiment and a second embodiment to be described later, in order to measure the “birefringence value ΔNyz” in the thickness direction of the polypropylene film, specifically, a phase difference measurement made by Otsuka Electronics Co., Ltd. The device No. RE-100 is used. The measurement of retardation (phase difference) is performed using the tilt method. More specifically, the principal axes in the in-plane direction of the film are x-axis and y-axis, and the thickness direction (normal direction to the in-plane direction) of the film is z-axis. The slower axis in the higher direction is the x-axis. With the x-axis as the tilt axis, each retardation value when tilted by 10 ° with respect to the z-axis in the range of 0 ° to 50 ° is obtained. From the obtained retardation values, the y-axis direction with respect to the thickness direction (z-axis direction) is determined using the method described in Non-patent document “Hiroshi Awaya, Introduction to Polarizing Microscopes of Polymer Materials, pp. 105-120, 2001”. Is calculated. First, for each inclination angle φ, the measured retardation value R is divided by the thickness d subjected to inclination correction to obtain R / d. For each R / d of φ = 10 °, 20 °, 30 °, 40 °, and 50 °, the difference from the R / d of φ = 0 ° was obtained, and these were further divided by sin2r (r: refraction angle). Is the birefringence ΔNzy at each φ, and the sign is reversed to obtain the birefringence value ΔNyz. The birefringence value ΔNyz is calculated as the average value of ΔNyz at φ = 20 °, 30 °, 40 °, and 50 °. For example, in the successive stretching method, when the stretching ratio in the TD direction (width direction) is higher than the stretching ratio in the MD direction (flow direction), the TD direction becomes a slow axis (x axis) and the MD direction becomes y. Axis. When polypropylene is used, the value of the refraction angle r at each inclination angle for polypropylene is the value described on page 109 of the above-mentioned document.

In the first embodiment, and in a second embodiment described later, the “birefringence value ΔNxz” with respect to the thickness direction of the polypropylene film is the retardation value R measured at an inclination angle φ = 0 °, The ΔNzy obtained above is divided by the value obtained by dividing the value by the thickness d to calculate a birefringence value ΔNxz.
A more specific method for measuring the plane orientation coefficient is based on the method described in Examples.

ポリプロピレン The polypropylene film contains a polypropylene resin, and the constituent material is not particularly limited as long as the heat shrinkage ratio is 0.25 or more and 0.60 or less.

含有 The content of the polypropylene resin is preferably 90% by mass or more, more preferably 95% by mass or more with respect to the whole polypropylene film (when the whole polypropylene film is 100% by mass). The upper limit of the content of the polypropylene resin is, for example, 100% by mass, 98% by mass, or the like based on the entire polypropylene film. The polypropylene resin may contain one kind of polypropylene resin alone, or may contain two or more kinds of polypropylene resins. The polypropylene resin is preferably a homopolypropylene resin.

Here, when the polypropylene film contains two or more kinds of polypropylene resins, the polypropylene resin having a higher content is referred to as “main component polypropylene resin” in this specification. In addition, when the polypropylene film contained in the polypropylene film is one kind, the polypropylene resin is referred to as “main component polypropylene resin” in this specification.

Hereinafter, in the present specification, when it is referred to as `` polypropylene resin '' without specifically specifying whether or not it is the main component, unless otherwise specified, a polypropylene resin as a main component and a polypropylene resin other than the main component Means both. For example, when it is described that the weight average molecular weight Mw of the polypropylene resin is preferably 250,000 or more and 450,000 or less, the weight average molecular weight Mw of the polypropylene resin as a main component is 250,000 or more and 450,000. It is preferable that the weight average molecular weight Mw of the polypropylene resin other than the main component is 250,000 or more and 450,000 or less.

The weight average molecular weight Mw of the polypropylene resin is preferably from 250,000 to 450,000, and more preferably from 250,000 to 400,000. When the weight average molecular weight Mw of the polypropylene resin is 250,000 or more and 450,000 or less, the resin fluidity becomes appropriate. As a result, it is easy to control the thickness of the cast raw sheet, and it is easy to produce a thin stretched film with good thickness uniformity. Further, from the viewpoints of mechanical properties, thermo-mechanical properties, stretch formability and the like of the biaxially stretched polypropylene film, the weight average molecular weight Mw is preferably from 250,000 to 450,000. When two or more types of polypropylene resins are used, it is preferable to use a combination of the above polypropylene resin having a Mw of 250,000 or more and less than 330,000 and a polypropylene resin having a Mw of 330,000 or more and 450,000 or less.
The number average molecular weight Mn of the polypropylene resin is preferably from 30,000 to 53,000, and more preferably from 33,000 to 52,000.
The z-average molecular weight Mz of the polypropylene resin is preferably from 500,000 to 21,000,000, more preferably from 700,000 to 17,000.

The molecular weight distribution [(weight average molecular weight Mw) / (number average molecular weight Mn)] of the polypropylene resin is preferably 5 or more, 12 or less, more preferably 5 or more and 11 or less, and 5 or more and 10 or less. Is more preferable. When the molecular weight distribution [(weight average molecular weight Mw) / (number average molecular weight Mn)] of the polypropylene resin is 5 or more and 12 or less, appropriate resin fluidity can be obtained at the time of biaxial stretching, and ultrathin without thickness unevenness. This is preferable because it becomes easy to obtain a stretched biaxially stretched propylene film.
The molecular weight distribution [(z-average molecular weight Mz) / (number-average molecular weight Mn)] of the polypropylene resin is preferably 10 or more and 70 or less, more preferably 15 or more and 60 or less, and 15 or more and 50 or less. Is more preferable.

In this specification, the weight average molecular weight (Mw), number average molecular weight (Mn), z average molecular weight (Mz), and molecular weight distribution (Mw / Mn and Mz / Mn) of the polypropylene resin are gel permeation. It is a value measured using a chromatograph (GPC) device. More specifically, it is a value measured using HLC-8121GPC-HT (trade name), a high temperature GPC measuring instrument with a built-in differential refractometer (RI) manufactured by Tosoh Corporation. As a GPC column, three TSKgel @ GMHHR-H (20) HT manufactured by Tosoh Corporation are used in combination. The column temperature is set to 140 ° C., and trichlorobenzene is flown at a flow rate of 1.0 ml / 10 minutes as an eluent to obtain measured values of Mw and Mn. A calibration curve for the molecular weight M is prepared using standard polystyrene manufactured by Tosoh Corporation, and the measured values are converted to polystyrene values to obtain Mw, Mn, and Mz. Here, the logarithm of the base 10 of the molecular weight M of the standard polystyrene is called a logarithmic molecular weight (“Log (M)”).

In the molecular weight differential distribution curve, the polypropylene resin has a difference obtained by subtracting a differential distribution value when Log (M) = 6.0 from a differential distribution value when Log (M) = 4.5 (hereinafter, referred to as “logarithmic molecular weight”). (Also referred to as “differential distribution value difference D _M ”) is preferably −5% to 14%, more preferably −4% to 12%, and more preferably −4% to 10%. Is more preferred.
Note that the difference (differential distribution value difference D _M ) obtained by subtracting the differential distribution value when Log (M) = 6.0 from the differential distribution value when logarithmic molecular weight Log (M) = 4.5 is − "5% or more and 14% or less" means a typical distribution of components having a molecular weight of 10,000 to 100,000 on the low molecular weight side from the value of Mw of the polypropylene resin (hereinafter, also referred to as "low molecular weight components"). Log (M) as a representative distribution value of a component having a logarithmic molecular weight Log (M) = 4.5 as a value and a component having a molecular weight of about 1,000,000 on the high molecular weight side (hereinafter also referred to as “high molecular weight component”). Comparing the components around = 6.0, it can be understood that when the difference is positive, there are more low molecular weight components, and when the difference is negative, there are more high molecular weight components.

That is, for example, in the case where the molecular weight distribution Mw / Mn is 5 to 12, the molecular weight distribution Mw / Mn is 5 to 12 merely represents the width of the molecular weight distribution. The quantitative relationship between the high molecular weight component and the low molecular weight component therein is unknown. From the viewpoint of resin fluidity, stretch moldability, and thickness uniformity, the polypropylene resin has a differential distribution value difference of -5% as compared with a component having a molecular weight of 10,000 to 100,000 and a component having a molecular weight of 1,000,000. It is preferable to use a polypropylene resin so as to be at least 14%.

微分 The differential distribution value is a value obtained as follows using GPC. A curve showing the intensity over time (generally also referred to as "elution curve") obtained by a differential refraction (RI) detector of GPC is used. Using a calibration curve obtained using standard polystyrene, the time axis is converted into a logarithmic molecular weight (Log (M)), whereby the elution curve is converted into a curve showing the intensity with respect to Log (M). Since the RI detection intensity is proportional to the component concentration, assuming that the entire area of the curve indicating the intensity is 100%, an integral distribution curve with respect to the logarithmic molecular weight Log (M) can be obtained. The differential distribution curve is obtained by differentiating this integral distribution curve by Log (M). Therefore, the “differential distribution” means a differential distribution of the concentration fraction with respect to the molecular weight. From this curve, a differential distribution value at a specific Log (M) is read.

The mesopentad fraction ([mmmm]) of the polypropylene resin is preferably less than 98.0%, more preferably 97.5% or less, further preferably 97.4% or less, and 97% or less. 0.0% or less is particularly preferred. Further, the mesopentad fraction is preferably at least 94.0%, more preferably at least 94.5%, even more preferably at least 95.0%. When the mesopentad fraction is within the above numerical range, the crystallinity of the resin is appropriately improved by moderately high stereoregularity, and the initial withstand voltage and the withstand voltage for a long period are improved, while the cast raw sheet is improved. The desired extensibility can be obtained by an appropriate solidification (crystallization) speed at the time of molding.

The mesopentad fraction ([mmmm]) is an index of stereoregularity that can be obtained by high-temperature nuclear magnetic resonance (NMR) measurement. In this specification, the mesopentad fraction ([mmmm]) refers to a value measured using a high-temperature Fourier transform nuclear magnetic resonance apparatus (high-temperature FT-NMR), JNM-ECP500, manufactured by JEOL Ltd. The observation nucleus was ¹³ C (125 MHz), the measurement temperature was 135 ° C., and the solvent for dissolving the polypropylene resin was o-dichlorobenzene (ODCB: a mixed solvent of ODCB and deuterated ODCB (mixing ratio = 4/1). For the measurement method using high-temperature NMR, for example, refer to the method described in “Japanese Analytical Chemistry and Polymer Analysis Research Council, edited by New Edition Polymer Analysis Handbook, Kinokuniya Shoten, 1995, p. 610”. A more detailed method for measuring the mesopentad fraction ([mmmm]) is based on the method described in Examples.

ヘ The heptane-insoluble content (HI) of the polypropylene resin is preferably 96.0% or more, more preferably 97.0% or more. Further, the heptane-insoluble content (HI) of the polypropylene resin is preferably 99.5% or less, more preferably 99.0% or less. Here, the heptane-insoluble content indicates that the greater the amount, the higher the stereoregularity of the resin. When the heptane-insoluble content (HI) is 96.0% or more and 99.5% or less, the crystallinity of the resin is appropriately improved due to moderately high stereoregularity, and the withstand voltage at high temperatures is improved. I do. On the other hand, the rate of solidification (crystallization) at the time of forming the cast raw sheet is appropriate, and the sheet has appropriate stretchability. The method for measuring heptane-insoluble matter (HI) is based on the method described in Examples.

The polypropylene resin preferably has a melt flow rate (MFR) of 1.0 to 8.0 g / 10 min, more preferably 1.5 to 7.0 g / 10 min, and more preferably 2.0 to 6.0 g. / 10 min is more preferable. The melt flow rate of the polypropylene resin is measured by the method described in Examples.

When the polypropylene film contains two or more types of polypropylene resins, the main component polypropylene resin has at least a weight average molecular weight Mw of 250,000 or more and less than 34.5 million, and an MFR of 4 to 8 g / 10 min. Is preferred. When two or more types of polypropylene resins are contained in the polypropylene film, the polypropylene resin other than the main component has at least a weight average molecular weight Mw of 34.5 to 450,000 and an MFR of 1 g / 10 min to 4 g. It is preferably less than / 10 min (more preferably 1 g / 10 min or more and 3.9 g / 10 min or less).

The polypropylene resin can be produced by using a generally known polymerization method. Examples of the polymerization method include a gas phase polymerization method, a bulk polymerization method, and a slurry polymerization method.

The polymerization may be a single-stage (one-stage) polymerization using one polymerization reactor or a multi-stage polymerization using two or more polymerization reactors. Further, the polymerization may be carried out by adding hydrogen or a comonomer as a molecular weight modifier into the reactor.

触媒 A generally known Ziegler-Natta catalyst can be used as a catalyst at the time of polymerization, and is not particularly limited as long as the polypropylene resin can be obtained. The catalyst may include a promoter component and a donor. The molecular weight, molecular weight distribution, stereoregularity, and the like can be controlled by adjusting the catalyst and the polymerization conditions.

分子 The molecular weight distribution and the like of the polypropylene resin can be adjusted by resin mixing (blend). For example, there is a method of mixing two or more resins having different molecular weights and molecular weight distributions from each other. Generally, assuming that the main resin is a resin having a higher or lower average molecular weight than the main resin and the total resin is 100% by mass, two types of polypropylene mixed with 55% to 90% by mass of the main resin are used. The system is preferable because the amount of the low molecular weight component can be easily adjusted.

When the above-mentioned mixing adjustment method is adopted, a melt flow rate (MFR) may be used as a standard of the average molecular weight. In this case, the difference in MFR between the main resin and the additional resin is preferably set to about 1 to 30 g / 10 minutes from the viewpoint of convenience in adjustment.

The method of mixing the resin is not particularly limited, but a method of dry-blending a polymer powder of the main resin and the additional resin, or a pellet using a mixer or the like, a polymer powder of the main resin and the additional resin, or a pellet. Is supplied to a kneading machine and melt-kneaded to obtain a blended resin.

The mixer and the kneader are not particularly limited. The kneading machine may be any of a single screw type, a twin screw type, and a multi-screw type more than that. In the case of a screw type having two or more shafts, any of a kneading type of co-rotation and a rotation in different directions may be used.

ブレンド In the case of blending by melt kneading, the kneading temperature is not particularly limited as long as a good kneaded material is obtained. Generally, it is in the range of 200 ° C. to 300 ° C., and preferably 230 ° C. to 270 ° C. from the viewpoint of suppressing the deterioration of the resin. Further, in order to suppress the deterioration during kneading and mixing of the resin, the kneading machine may be purged with an inert gas such as nitrogen. The melt-kneaded resin may be pelletized to an appropriate size using a generally known granulator. Thereby, a mixed polypropylene raw material resin pellet can be obtained.

(4) The total ash content due to the polymerization catalyst residue and the like contained in the polypropylene raw material resin is preferably 50 ppm or less based on the polypropylene resin (100 parts by weight).

The total ash content (total ash content contained in the polypropylene raw material resin) is preferably 5 ppm or more and 35 ppm or less, and more preferably 5 ppm or more and 30 ppm in order to improve the electrical characteristics of the capacitor while suppressing generation of low molecular components having polarity. The following is more preferable, and 10 ppm or more and 25 ppm or less are still more preferable.

The polypropylene film may contain an additive. The “additive” is generally an additive used for a polypropylene resin, and is not particularly limited as long as a polypropylene film having the heat shrinkage ratio of 0.25 or more and 0.6 or less can be obtained. .

Examples of the additives include antioxidants, chlorine absorbers, ultraviolet absorbers, lubricants, plasticizers, flame retardants, antistatic agents, inorganic fillers, and organic fillers. Examples of the inorganic filler include barium titanate, strontium titanate, and aluminum oxide. The polypropylene resin may include the additive in an amount that does not adversely affect the polypropylene film.

The metal layer functions as an electrode when the metal layer-integrated polypropylene film is used as a capacitor. As the metal used for the metal layer, for example, a metal simple substance such as zinc, lead, silver, chromium, aluminum, copper, and nickel, a mixture of a plurality of kinds thereof, and an alloy thereof can be used. Taking into account the cost, the economy and the performance of the capacitor, zinc and aluminum are preferred.

Next, a method for manufacturing the metal layer-integrated polypropylene film according to the first embodiment will be described. The metal layer-integrated polypropylene film according to the first aspect of the present invention is preferably manufactured by the method for manufacturing a metal-layer-integrated polypropylene film described below. It does not need to be manufactured by the manufacturing method.

The method for producing a metal layer-integrated polypropylene film according to the first embodiment includes:
Step A of preparing a polypropylene film,
Step B to obtain a metal layer-integrated polypropylene film by laminating a metal layer on one or both sides of the polypropylene film prepared in the step A,
When the heat shrinkage in the first direction of the polypropylene film prepared in the step A is A, and the heat shrinkage B in the first direction of the metal layer-integrated polypropylene film obtained in the step B is A, the heat shrinkage A The heat shrinkage ratio [(heat shrinkage B) / (heat shrinkage A)] of the heat shrinkage ratio B is 0.25 or more and 0.6 or less.

First, the step A will be described.

場合 When the polypropylene film is a biaxially oriented polypropylene film, the cast raw sheet before stretching for producing the biaxially oriented polypropylene film can be produced as follows. However, the method of manufacturing the cast raw sheet according to the first embodiment is not limited to the method described below.

First, resin pellets, dry-blended resin pellets, or resin pellets prepared in advance by melt-kneading are supplied to an extruder and melted by heating.
The melt-kneading temperature varies depending on the type of the thermoplastic resin. In the case of a polypropylene resin, the set temperature of the extruder during heating and melting is preferably from 220 to 280 ° C, more preferably from 230 to 270 ° C. Further, the resin temperature during melting by heating is preferably from 220 to 280 ° C, more preferably from 230 to 270 ° C. The resin temperature at the time of heating and melting is a value measured by a thermometer inserted into the extruder.
The extruder set temperature and the resin temperature during heating and melting are selected in consideration of the physical properties of the resin used. By setting the resin temperature at the time of heating and melting within the above numerical range, the deterioration of the resin can also be suppressed.

Next, the molten resin is extruded into a sheet shape using a T-die, and cooled and solidified by at least one or more metal drums to form an unstretched cast raw sheet.
The surface temperature of the metal drum (the temperature of the metal drum that first contacts after extrusion) is preferably 50 to 100 ° C, more preferably 60 to 80 ° C. The surface temperature of the metal drum can be determined according to the physical properties of the resin used.

The thickness of the cast raw sheet is not particularly limited as long as the polypropylene film can be obtained, but is usually preferably 0.05 mm to 2 mm, and more preferably 0.1 mm to 1 mm. Is more preferred.

ポリプロピレン The polypropylene film according to the first embodiment can be suitably manufactured as follows. However, the method for producing the polypropylene film according to the first embodiment is not limited to the method described below.

The polypropylene film can be manufactured by subjecting the resin cast raw sheet to a stretching treatment. The stretching is preferably biaxial stretching in which the film is biaxially oriented vertically and horizontally, and as a stretching method, a sequential biaxial stretching method is preferred. As a sequential biaxial stretching method, for example, first, a cast raw sheet is kept at a temperature of 100 to 170 ° C., and is passed through rolls provided with a speed difference to 3 to 7 times in the MD direction (flow direction, longitudinal direction). Stretch. The nip pressure is 0.35 to 0.5 MPa.
The temperature at the time of stretching in the MD direction is preferably 100 to 170 ° C, more preferably 120 to 160 ° C, and still more preferably 130 to 150 ° C. The stretching ratio in the MD direction stretching is preferably 3 to 7 times, more preferably 4 to 6 times, and even more preferably 4 to 5 times. In addition, the nip pressure during MD stretching is preferably 0.35 to 0.45 MPa, more preferably 0.36 to 0.44 MPa, and even more preferably 0.37 to 0.43 MPa. The higher the nip pressure during MD stretching, the lower the heat shrinkage tends to be, and the lower the nip pressure, the higher the heat shrinkage tends to be.
After stretching in the MD direction, the sheet is guided to a tenter and stretched 3 to 11 times in the TD direction (lateral direction, width direction). The temperature at the time of stretching in the TD direction is preferably 155 to 170 ° C. Thereafter, relaxation and heat setting are performed 2 to 10 times. Thus, a biaxially oriented polypropylene film is obtained.

The polypropylene film may be subjected to a corona discharge treatment online or offline after the stretching and heat fixing steps in order to enhance the adhesive properties in a later step such as a metal vapor deposition step. The corona discharge treatment can be performed using a known method. It is preferable to use air, carbon dioxide gas, nitrogen gas, or a mixed gas thereof as the atmosphere gas.

ポリプロピレン A polypropylene film can be obtained as described above. In particular, a polypropylene film having a heat shrinkage A in the first direction of 2.0% or more and 10.0% or less can be suitably obtained.

Step A for preparing a polypropylene film has been described above.

Next, the step B of obtaining a polypropylene film integrated with a metal layer by laminating a metal layer on one or both surfaces of the polypropylene film prepared in the step A will be described. However, the step B according to the first embodiment is not limited to the steps described below.

In step B, a metal layer is laminated on one or both sides of the polypropylene film to be processed as a capacitor to obtain a metal layer-integrated polypropylene film.

方法 As a method of laminating a metal layer on one side or both sides of the polypropylene film, for example, a vacuum deposition method or a sputtering method can be exemplified. From the viewpoints of productivity, economy, and the like, a vacuum evaporation method is preferable. As the vacuum deposition method, a crucible method, a wire method, and the like can be generally exemplified, but there is no particular limitation, and an optimum method can be appropriately selected.

蒸着 As the deposition conditions in the vacuum deposition method, the temperature of the cooling roll is preferably −23 ° C. or higher, more preferably −22 ° C. or higher, and still more preferably −20 ° C. or higher. When the temperature of the cooling roll is -23 ° C. or higher, the polypropylene film can be largely heat-shrinked during lamination of the metal layer, and the heat shrinkage B of the obtained metal layer-integrated polypropylene film tends to be small. . If the heat shrinkage B can be reduced, the shrinkage ratio can be easily reduced to 0.6 or less. The temperature of the cooling roll is preferably −18 ° C. or lower, and more preferably −19 ° C. or lower, from the viewpoint of preventing the polypropylene film from losing heat.

において In the vacuum deposition method, the temperature of the evaporation source is controlled by the amount of electricity. As the deposition conditions in the vacuum deposition method, the amount of electricity supplied to the evaporation source is preferably 650 A or more, more preferably 700 A or more, and even more preferably 800 A or more. When the amount of current is increased (when the temperature of the evaporation source is set higher), the polypropylene film can be largely thermally contracted when the metal layers are laminated, and the thermal contraction rate B of the obtained metal layer integrated polypropylene film is reduced. Tend to be able to. If the heat shrinkage B can be reduced, the shrinkage ratio can be easily reduced to 0.6 or less. From the viewpoint of preventing heat loss of the polypropylene film, the amount of electricity is preferably 900 A or less, more preferably 850 A or less.

In the vacuum deposition method, the thickness of the metal layer is controlled by the film resistance. As the deposition conditions in the vacuum deposition method, the film resistance of an aluminum film is preferably 20 Ω / sq or less, and more preferably 17 Ω / sq or less. In the case of a zinc film, it is preferably 5 Ω / sq or less, more preferably 4 Ω / sq or less. The small film resistance means that the thickness of the metal layer is large. When the film resistance is reduced (when the thickness of the metal layer is increased), the metal layer is exposed to heat for a long time for lamination. Therefore, if the thickness is set to be large, the polypropylene film can be greatly shrunk by being exposed to heat for a long time during lamination of the metal layer, and the heat shrinkage B of the obtained metal layer integrated polypropylene film can be reduced. Tend to be able to. If the heat shrinkage B can be reduced, the shrinkage ratio can be easily reduced to 0.6 or less. In the case of an aluminum film, the film resistance is preferably 1 Ω / sq or more, more preferably 5 Ω / sq or more, from the viewpoint of self-healing property (self-healing property). In the case of a zinc film, it is preferably at least 1 Ω / sq, more preferably at least 2 Ω / sq. In addition, the self-healing property means that, when a defective portion occurs in the polypropylene film, the function of the capacitor is recovered by instantaneously evaporating the metal of the vapor deposition layer by the applied energy or the energy of the capacitor itself. .
The thickness (film resistance) of the metal layer can be adjusted by the speed of the vapor deposition line and the temperature of the vapor source.

The margin pattern when the metal layer is laminated by vapor deposition is not particularly limited, but from the viewpoint of improving characteristics such as the security of the capacitor, a pattern including a so-called special margin such as a fishnet pattern or a T-margin pattern. Is preferably applied to one surface of the film. This improves the security and is effective in preventing destruction of the capacitor and short circuit.

As a method of forming a margin, a generally known method such as a tape method or an oil method can be used without any limitation.

工程 In the step B, after a metal layer is laminated on one or both sides of the polypropylene film, a post-heating treatment may be further performed. By performing the post-heating treatment, the metal layer-integrated polypropylene film before becoming a product can be thermally shrunk, and as a result, the heat shrinkage B of the metal layer-integrated polypropylene film as a product can be reduced. . If the heat shrinkage B can be reduced, the shrinkage ratio can be easily reduced to 0.6 or less. The conditions for the post-heating treatment include, for example, application of silicone oil heated to 120 to 130 ° C.

As described above, an example of the method for producing the metal layer-integrated polypropylene film having the shrinkage ratio of 0.25 or more and 0.60 or less has been described.

The metal layer-integrated polypropylene film can be laminated or wound by a conventionally known method to form a film capacitor.

The first embodiment (the first embodiment according to the present invention) has been described above.

<Embodiment according to second invention>
Hereinafter, a second embodiment of the present invention will be described. Note that the metal layer integrated polypropylene film according to the second embodiment of the present invention has a heat shrinkage ratio [(heat shrinkage ratio) of heat shrinkage A and heat shrinkage B similar to the first embodiment of the present invention. (Shrinkage ratio B) / (heat shrinkage ratio A)] need not be 0.25 or more and 0.60 or less.

The metal layer-integrated polypropylene film according to the embodiment (hereinafter, also referred to as “second embodiment”) according to the second invention,
A polypropylene film,
A metal layer-integrated polypropylene film having a metal layer laminated on one side or both sides of the polypropylene film,
The heat shrinkage A in the first direction of the polypropylene film before laminating the metal layer is greater than 3.0%,
The heat shrinkage B in the first direction of the metal layer-integrated polypropylene film is 2.4% or less.

In the metal layer-integrated polypropylene film according to the second embodiment, the heat shrinkage B in the first direction of the metal layer-integrated polypropylene film is 2.4% or less, preferably 2.3% or less, and 2.2. % Or less, more preferably 2.1% or less. Since the heat shrinkage B is 2.4% or less, the relative displacement of the contact surface between the metal layer-integrated polypropylene film and the metallikon electrode due to long-term use after forming a capacitor is suppressed. As a result, exfoliation of the metallikon electrode can be suppressed. This point is clear from the embodiment. The heat shrinkage B is, for example, 0.5% or more, 0.8% or more, 1.0% or more, or the like. When the heat shrinkage B is 0.5% or more, the element is suitably wound and fastened during heat treatment after the element is wound. As a result, voids between the films are removed, and the shape is stabilized. Further, the withstand voltage can be improved. The method for measuring the heat shrinkage B is as described in the section of the first embodiment.

調整 The method of adjusting the heat shrinkage B is not particularly limited. For example, the method described in the section of the first embodiment can be adopted.

In the metal layer-integrated polypropylene film according to the second embodiment, the heat shrinkage A (the heat shrinkage in the first direction of the polypropylene film before the metal layer is laminated) is larger than 3.0% and 3.1. % Or more is preferable, 3.5% or more is more preferable, and 4.0% or more is still more preferable. Since the heat shrinkage A is larger than 3.0%, there is room for selection of the material of the polypropylene film and adjustment of the production conditions of the polypropylene film. In other words, there is little restriction that a raw material resin must be selected such that the heat shrinkage of the polypropylene film before the metal layer is laminated becomes small. The upper limit of the heat shrinkage A is not particularly limited, but is, for example, 9.0% or less, 8.0% or less, 7.5% or less from the viewpoint of production of the polypropylene film.

The method of measuring the heat shrinkage A is as described in the first embodiment.

As described above, in the second embodiment, a polypropylene film having a heat shrinkage factor A of more than 3.0% is used. That is, there is no need to produce a polypropylene film having a small heat shrinkage A. Therefore, room for selecting a material for the polypropylene film is secured. Therefore, it is relatively easy to obtain a polypropylene film having a heat shrinkage factor A of more than 3.0%, and it may be selected from various materials (such as raw material resins).

The heat shrinkage ratio [(heat shrinkage B) / (heat shrinkage A)] between the heat shrinkage A and the heat shrinkage B is preferably 0.65 or less, more preferably 0.62 or less, and 0. .60 or less is more preferable. When the heat shrinkage ratio is 0.65 or less, it can be said that the polypropylene film is relatively largely shrunk after the metal layer is stacked, as compared to before the metal layer is stacked. That is, if the heat shrinkage ratio is 0.65 or less, the metal layer-integrated polypropylene film has already largely shrunk, and even if it receives a heat history, it is difficult to shrink any more. I have. As a result, when used as a capacitor, it is possible to further suppress peeling of the metallikon electrode. The heat shrinkage ratio is preferably small, but may be, for example, 0.20 or more, 0.25 or more, 0.28 or more.

厚 The thickness of the metal layer-integrated polypropylene film is preferably within the numerical range described in the section of “First Embodiment of the Present Invention”.

第一 The dimensional change in the first direction at 120 ° C. of the metal layer-integrated polypropylene film is preferably within the numerical range described in the section of “first embodiment of the present invention”. The method of controlling the dimensional change rate in the first direction at 120 ° C. is not particularly limited. For example, the method described in the section of the first embodiment can be adopted.

ポリプロピレン Hereinafter, a description will be given of a polypropylene film included in a metal layer-integrated polypropylene film as a product after a metal layer is laminated. That is, hereinafter, before lamination of the metal layer, or after lamination of the metal layer, without explicitly specifying, when referred to as `` polypropylene film '', unless otherwise specified, This will be described as meaning a polypropylene film after a metal layer is laminated.

厚 The thickness of the polypropylene film is preferably within the numerical range described in the section of “First Embodiment of the Present Invention”.

金属 The thickness of the metal layer in the metal layer-integrated polypropylene film is preferably within the numerical range described in the section of “first embodiment of the present invention”.

The polypropylene film may be a biaxially stretched film, a uniaxially stretched film, or a non-stretched film. Among them, a biaxially stretched film is preferable. When the polypropylene film is biaxially stretched, the heat shrinkage in the first direction of the polypropylene film tends to be larger than before the biaxial stretching. Therefore, when the polypropylene film is biaxially stretched, it is easy to obtain one having a heat shrinkage in the first direction of more than 3.0%.

The details of the plane orientation coefficient ΔP are as described in the section of the first embodiment.

The polypropylene film contains a polypropylene resin, and the constituent material is not particularly limited as long as the heat shrinkage A in the first direction of the polypropylene film before laminating the metal layer is larger than 3.0%.

含有 The content of the polypropylene resin may have the same configuration as that described in the section of the first embodiment of the present invention.

ポリプロピレン As the polypropylene resin, the polypropylene resin described in the section of “first embodiment of the present invention” can be adopted.

(4) The total ash content due to the polymerization catalyst residue and the like contained in the polypropylene raw material resin is preferably within the numerical range described in the section of “First Embodiment of the Present Invention”.

The polypropylene film may contain an additive. As the additive, those described in the section of the first embodiment of the present invention can be employed.

The metal layer functions as an electrode when the metal layer-integrated polypropylene film is used as a capacitor. As the metal used for the metal layer, those described in the section of the first embodiment of the present invention can be employed.

Next, a method for manufacturing a metal layer-integrated polypropylene film according to the second embodiment will be described. The metal layer-integrated polypropylene film according to the second aspect of the present invention is preferably manufactured by the method for manufacturing a metal-layer-integrated polypropylene film described below. It does not need to be manufactured by the manufacturing method.

The method for producing a metal layer-integrated polypropylene film according to the second embodiment includes:
A step A of preparing a polypropylene film having a heat shrinkage A in the first direction of more than 3.0%;
Step B to obtain a metal layer-integrated polypropylene film by laminating a metal layer on one or both sides of the polypropylene film prepared in the step A,
The heat shrinkage B in the first direction of the metal layer-integrated polypropylene film obtained in the step B is 2.4% or less.

は As the details of the step A and the step B, the step A and the step B described in the section of the first embodiment can be adopted.

That is, if the step A described in the section of the first embodiment is adopted, a polypropylene film having a heat shrinkage A in the first direction of more than 3.0% can be obtained.

In addition, if the step B described in the section of the first embodiment is adopted, a metal layer integrated polypropylene film having a heat shrinkage B in the first direction of 2.4% or less can be obtained.

The second embodiment (the second embodiment according to the present invention) has been described above.

Hereinafter, the present invention (the first present invention and the second present invention) will be described in detail using examples, but the present invention (the first present invention and the second present invention) The present invention is not limited to the following examples unless it exceeds the gist.

The following embodiment is an embodiment according to the first present invention and is an embodiment according to the second present invention.

(Polypropylene resin)
Table 1 shows the polypropylene resins used for producing the polypropylene films of the examples and the comparative examples.
Resin A is a product manufactured by Prime Polymer Co., Ltd. (5000 ppm of Irganox (registered trademark) 1010 as an antioxidant and 20 ppm of 2,5-dimethyl-2,5-di (t-butylperoxy) hexane are added thereto). A resin whose molecular weight distribution is adjusted by subjecting it to a peroxide decomposition treatment by melt-kneading with a granulator.
Resin B is a product manufactured by Prime Polymer Co., Ltd. (a resin to which 5000 ppm of Irganox (registered trademark) 1010 is added as an antioxidant).
Resin C is HPT-1 (resin to which 5000 ppm of Irganox (registered trademark) 1010 is added as an antioxidant) manufactured by Daehan Oil Chemical Company.
Table 1 shows the weight average molecular weight (Mw), number average molecular weight (Mn), z average molecular weight (Mz), molecular weight distribution (Mw / Mn), and molecular weight distribution (Mz / Mn) of each resin. These values are in the form of raw resin pellets. The measuring method is as follows. Resin A, resin B and resin C are all homopolypropylene resins.

<Measurement of weight average molecular weight (Mw), number average molecular weight (Mn), z average molecular weight (Mz), molecular weight distribution (Mw / Mn), and molecular weight distribution (Mz / Mn) of polypropylene resin>
Using GPC (gel permeation chromatography), under the following conditions, weight average molecular weight (Mw), number average molecular weight (Mn), z average molecular weight (Mz), molecular weight distribution (Mw / Mn), and The molecular weight distribution (Mz / Mn) was measured.
Specifically, an HLC-8121GPC-HT type high temperature GPC device with a built-in differential refractometer (RI) manufactured by Tosoh Corporation was used. As a column, three TSKgel GMHHR-H (20) HT manufactured by Tosoh Corporation were connected and used. At a column temperature of 140 ° C., measurement was performed by flowing trichlorobenzene as an eluent at a flow rate of 1.0 ml / min. A calibration curve was prepared using standard polystyrene manufactured by Tosoh Corporation, and the value of the measured molecular weight was converted into a value of polystyrene to obtain a weight average molecular weight (Mw), a number average molecular weight (Mn), and a z average. The molecular weight (Mz) was obtained. The molecular weight distribution (Mw / Mn) was obtained using the values of Mw and Mn. The molecular weight distribution (Mz / Mn) was obtained using the values of Mz and Mn.

<Measurement of the difference (differential distribution value difference D _M ) between the differential distribution value when logarithmic molecular weight log (M) = 4.5 and the differential distribution value when logarithmic molecular weight log (M) = 6.0>
For each resin, a differential distribution value when the logarithmic molecular weight log (M) = 4.5 and a differential distribution value when the logarithmic molecular weight log (M) = 6.0 were obtained by the following methods. First, a time curve (elution curve) of the intensity distribution detected using the RI detector is converted into a distribution curve for the molecular weight M (Log (M)) of the standard polystyrene using the calibration curve prepared using the standard polystyrene. Converted. Next, after obtaining an integral distribution curve for Log (M) when the total area of the distribution curve is 100%, this integral distribution curve is differentiated by Log (M) to obtain a differential distribution for Log (M). A curve was obtained. From this differential distribution curve, the differential distribution values when Log (M) = 4.5 and Log (M) = 6.0 were read. The difference between the differential distribution value when the differential distribution value when the Log (M) = 4.5 and Log (M) = 6.0 was differentiated distribution value difference _{D M.} In addition, a series of operations until obtaining the differential distribution curve was performed using analysis software built in the GPC measuring device used. Table 1 shows the results.

<Measurement of meso pentad fraction ([mmmm])>
Each resin was dissolved in a solvent, and measured using a high-temperature Fourier transform nuclear magnetic resonance apparatus (high-temperature FT-NMR) under the following conditions. Table 1 shows the results.
High temperature type nuclear magnetic resonance (NMR) device: JEOL Ltd., high temperature type Fourier transform nuclear magnetic resonance device (high temperature FT-NMR), JNM-ECP500
Observed nucleus: ¹³ C (125 MHz)
Measurement temperature: 135 ° C
Solvent: ortho-dichlorobenzene (ODCB: mixed solvent of ODCB and deuterated ODCB (mixing ratio = 4/1))
Measurement mode: single pulse proton broadband decoupling pulse width: 9.1 μsec (45 ° pulse)
Pulse interval: 5.5 sec
Number of integration: 4,500 times Shift standard: CH ₃ (mmmm) = 21.7 ppm
The pentad fraction representing the degree of stereoregularity is a combination (mmmm or mrrm) of a pentad of a co-located "meso (m)" and a co-located "racemo (r)" in a different direction. ) Was calculated as a percentage (%) from the integrated value of the intensity of each signal derived from the above. Regarding the assignment of each signal derived from mmmm, mrrm, and the like, for example, reference was made to the description of spectra such as “T. Hayashi et al., Polymer, Vol. 29, p. 138 (1988)”.

<Measurement of heptane insoluble matter (HI)>
Each resin was press-molded into 10 mm × 35 mm × 0.3 mm to prepare a measurement sample of about 3 g. Next, about 150 mL of heptane was added, and Soxhlet extraction was performed for 8 hours. Heptane insolubles were calculated from the sample mass before and after extraction. Table 1 shows the results.

<Measurement of melt flow rate (MFR)>
The melt flow rate (MFR) of each resin in the form of raw resin pellets was measured using a melt indexer manufactured by Toyo Seiki Co., Ltd. according to JIS K 7210, Condition M. Specifically, first, a sample weighed at 4 g was inserted into a cylinder at a test temperature of 230 ° C., and was preheated under a load of 2.16 kg for 3.5 minutes. Thereafter, the weight of the sample extruded from the bottom hole was measured for 30 seconds, and the MFR (g / 10 min) was obtained. The above measurement was repeated three times, and the average value was used as the measured value of MFR. Table 1 shows the results.

ポリプロピレン A polypropylene film and a metal layer-integrated polypropylene film were prepared using the above-mentioned resins, and the physical properties thereof were evaluated.

<Preparation of polypropylene film>
(Production Example 1)
The resin A is supplied to an extruder, melted at a temperature of 255 ° C., extruded using a T-die, wound around a metal drum having a surface temperature maintained at 94 ° C., solidified, and cast to a thickness of about 120 μm. An original sheet was produced. The obtained cast raw sheet was stretched 4.8 times in the MD direction (flow direction) by passing between rolls provided with a speed difference at a temperature of 139 ° C., and immediately cooled to room temperature (23 ° C.). At this time, the nip pressure was 0.40 MPa.
Next, it was guided to a tenter and stretched 10 times in the TD direction (width direction) at a temperature of 163 ° C. to obtain a biaxially stretched polypropylene film.
Here, the nip pressure means a nip roll above a roll having a higher rotation speed (a roll located at a position where stretching in the MD direction is started) among two rolls provided with a speed difference for longitudinal stretching. And refers to the pressure applied to the film when the film passes between the high-speed roll and the nip roll.

(Production Example 2)
Resin B and resin C were dry blended. The mixing ratio was (resin B) :( resin C) = 60: 40 in mass ratio. Thereafter, the dry-blended resin is supplied to an extruder, melted at a temperature of 255 ° C., extruded using a T die, wound around a metal drum having a surface temperature of 91.5 ° C., and solidified. A raw cast sheet having a thickness of about 120 μm was prepared. The obtained cast raw sheet was stretched 4.8 times in the MD direction (flow direction) by passing between rolls provided with a speed difference at a temperature of 139 ° C., and immediately cooled to room temperature (23 ° C.). At this time, the nip pressure was 0.40 MPa. Next, it was guided to a tenter and stretched 10 times in the TD direction (width direction) at a temperature of 163 ° C. to obtain a biaxially stretched polypropylene film.

(Production Example 3)
A biaxially stretched polypropylene film was obtained in the same manner as in Production Example 2 except that the nip pressure was changed to 0.30 MPa instead of 0.40 MPa.

<Measurement of Heat Shrinkage A in MD Direction of Polypropylene Film Before Laminating Metal Layer>
The polypropylene film manufactured in the manufacturing example was cut into a rectangle having a width of 20 mm and a length of 130 mm to prepare a measurement sample. At this time, cutting was performed with the MD direction as the length direction. Three measurement samples were prepared. Next, a portion having a length of 100 mm was measured with a ruler, and a mark was attached to the portion. Next, the three measurement samples were held in a hot air circulating thermostat at 120 ° C. for 15 minutes without load. Then, it cooled at room temperature (23 degreeC) and measured the dimension. The rate of change of the dimension after heating with respect to the dimension of 100 mm before heating at 120 ° C. was defined as the heat shrinkage rate A. Specifically, the following equation was used.
(Heat shrinkage A) = [[(dimension before heating) − (dimension after heating)] / (dimension before heating)] × 100 (%)
Note that conditions other than those described here conformed to “21. Dimensional change” of JIS C 2151: 2006. Table 2 shows the results.

<Preparation of metal layer integrated polypropylene film>
Using a vapor deposition apparatus (manufactured by ULVAC, product name: roll-up vacuum vapor deposition apparatus EWE-060), a metal layer was laminated on the polypropylene film obtained in each production example under the vapor deposition conditions shown in Table 2. Thus, a metal layer-integrated polypropylene film according to a comparative example was obtained. Specifically, a metal layer-integrated polypropylene film according to Examples and Comparative Examples was obtained as described below. The thicknesses of the metal layer-integrated polypropylene films according to Examples and Comparative Examples were all 2.5 μm. The thickness of the metal layer-integrated polypropylene film was measured in accordance with JIS-C2330 except that the thickness was measured at 100 ± 10 kPa using a paper thickness measuring device MEI-11 manufactured by Citizen Seimitsu.

FIG. 1 is a schematic perspective view for explaining a metal layer integrated type polypropylene film produced as an example and a comparative example.
As shown in FIG. 1, a metal layer integrated type polypropylene film 1 produced as an example and a comparative example is composed of a polypropylene film 2 and a metal deposition electrode 3 laminated on the polypropylene film 2 so as to leave an insulation margin 4. Have. The metal-deposited electrode 3 has a metal-deposited layer 3a laminated on the polypropylene film 2 so as to be in direct contact with the polypropylene film 2, and an electrode extraction portion 3b formed on a part of the upper surface of the metal-deposited layer 3a. The electrode extraction portion 3b is a portion called a so-called heavy edge.

FIG. 2 is a schematic diagram for explaining a method for producing a metal layer-integrated polypropylene film according to Examples and Comparative Examples. The metal layer-integrated polypropylene films produced in Examples and Comparative Examples were produced by a production apparatus described below.
As shown in FIG. 2, the apparatus for manufacturing a metal layer-integrated polypropylene film includes a dielectric film supply unit 101, an insulation margin forming unit 102, a pattern forming unit 103, a vapor deposition unit 104, and a winding roll 105. Prepare.

The dielectric film supply unit 101 supports the dielectric film roll 2R around which the polypropylene film 2 (the polypropylene film produced in the manufacturing example) is wound, and supplies the dielectric film 2. The polypropylene film 2 supplied from the dielectric film roll 2R is transported to the insulation margin forming unit 102.

(4) The insulating margin forming section 102 applies oil having a pattern corresponding to the pattern of the insulating margin 4 to the surface 2a of the polypropylene film 2 to form an oil mask. The oil mask is for preventing metal particles from adhering to a portion serving as an insulation margin in the metal layer-integrated polypropylene film 1 in a vapor deposition step. The insulation margin forming unit 102 vaporizes the oil stored in the oil tank and applies the oil directly to one surface 2a of the polypropylene film 2 from a nozzle (slit) provided in the tank to form an oil mask.

The pattern forming unit 103 applies oil to the one surface 2a of the polypropylene film 2 in a pattern substantially corresponding to the electrode pattern of the metal deposition layer 3a to form an oil mask. The oil mask is for preventing metal particles from adhering to a portion serving as a vertical margin or a horizontal margin in the metal layer-integrated polypropylene film 1 in a vapor deposition step. The pattern forming unit 103 includes an oil tank 103a, an anilox roll 103b, a transfer roll 103c, a plate roll 103d, and a backup roll 103e. The oil tank 103a vaporizes the stored oil and spouts it from a nozzle. The anilox roll 103b and the transfer roll 103c rotate with oil spouted from the nozzle of the oil tank 103a adhered to the outer peripheral surfaces thereof. The backup roll 103e faces the plate roll 103d via the polypropylene film 2 and contacts the surface 2b of the polypropylene film 2.

ポリプロピレン The polypropylene film 2 that has passed through the insulating margin forming section 102 and the pattern forming section 103 is transported to the vapor deposition section 104.

The vapor deposition unit 104 includes metal

vapor generation units

104a and 104b, and a cooling roll 104c that faces the metal

vapor generation units

104a and 104b via the polypropylene film 2. The metal vapor generation unit 104a generates a metal vapor by supplying an electric current to a metal wire, which is a material of the metal deposition layer 3a, on a heated boat, and generates the metal vapor. Is deposited. The metal vapor generation unit 104b heats and evaporates the metal that is the material of the electrode extraction unit 3b to generate metal vapor, and the metal vapor deposition layer previously formed on the surface 2a of the polypropylene film 2 by the metal vapor generation unit 104a. 3a is deposited on top of it. As a result, the metal deposition layer at the electrode take-out portion 3b becomes thicker than the metal deposition layers at other portions, and a heavy edge structure is formed. The metal vapor generated by the

metal vapor generators

104a and 104b adheres to portions other than the oil mask formed on the surface 2a of the polypropylene film 2 to form the metal vapor deposition electrode 3. The cooling roll 104b contacts the polypropylene film 2 and cools the polypropylene film 2.
The temperature of the metal vapor increases in accordance with the amount of current flowing (the amount of current).
The thickness of the metal deposition layer 3a is controlled by film resistance (resistance value per unit area). Since the resistance value is inversely proportional to the thickness, the lower the film resistance, the thicker the film.

The metal layer-integrated polypropylene film 1 formed by forming the metal deposition electrode 3 on the polypropylene film 2 by the vapor deposition unit 104 is conveyed to the take-up roll 105 and wound.

用い Using the above-described manufacturing apparatus, a metal-deposited electrode 3 was formed on the surface 2 a of the polypropylene film 2 to obtain a metal layer-integrated polypropylene film 1.

厚み The thickness of the metal layer-integrated polypropylene film was measured in accordance with JIS-C2330, except that the thickness was measured at 100 ± 10 kPa using a paper thickness measuring device MEI-11 manufactured by Citizen Seimitsu.

<Measurement method of film resistance>
Using a low resistance resistivity meter Loresta GX MCP-T610 manufactured by Mitsubishi Chemical Analytech Co., Ltd., a probe was applied to the produced metal layer integrated polypropylene film for measurement. The measurement was performed at five solid portions near the center in the film width direction (not at the electrode extraction portion 3b), and the average value was defined as the film resistance.

<Measurement of heat shrinkage B in MD direction of metal film integrated with polypropylene film>
The metal layer-integrated polypropylene films obtained in Examples and Comparative Examples were cut into rectangles having a width of 20 mm and a length of 130 mm to prepare measurement samples. At this time, cutting was performed with the MD direction as the length direction. Three measurement samples were prepared. Next, a portion having a length of 100 mm was measured with a ruler, and a mark was attached to the portion. Next, the three measurement samples were held in a hot air circulating thermostat at 120 ° C. for 15 minutes without load. Then, it cooled at room temperature (23 degreeC) and measured the dimension. The rate of change of the dimension after heating with respect to the dimension of 100 mm before heating at 120 ° C. was defined as the heat shrinkage B. Specifically, the following equation was used.
(Thermal shrinkage B) = [[(dimension before heating) − (dimension after heating)] / (dimension before heating)] × 100 (%)
The measurement conditions other than those described here conformed to “21. Dimensional change” of JIS C 2151: 2006. Table 2 shows the results.
Table 2 also shows the heat shrinkage ratio of the heat shrinkage A and the heat shrinkage B [(heat shrinkage B) / (heat shrinkage A)].

<Measurement of plane orientation coefficient>
<Retardation value>
First, the retardation (retardation) values of the polypropylene films according to Examples and Comparative Examples were measured by the tilt method as described below.
Measuring machine: Retardation measuring device RE-100 manufactured by Otsuka Electronics Co., Ltd.
Light source: LED light source having a wavelength of 550 nm Measurement method: The angle dependence of the retardation value was measured by the following tilt method. The principal axes in the in-plane direction of the film are x-axis and y-axis, and the thickness direction of the film (normal direction to the in-plane direction) is the z-axis. When the axis is the x-axis, each retardation value when the x-axis is inclined by 10 ° with respect to the z-axis in the range of 0 ° to 50 ° with the x-axis as the inclined axis was determined. For example, in the sequential stretching method, when the stretching ratio in the TD direction (width direction) is higher than the stretching ratio in the MD direction (flow direction), the TD direction becomes the slow axis (x axis) and the MD direction becomes the y axis. .

<Birefringence value and plane orientation coefficient ΔP>
The plane orientation coefficient ΔP was calculated from the retardation value as described in the non-patent document “Hiroshi Awaya, Introduction to Polarizing Microscopes of Polymer Materials, pp. 105-120, 2001”.
First, for each inclination angle φ, R / d was obtained by dividing the measured retardation value R by the thickness d subjected to inclination correction. For each R / d of φ = 10 °, 20 °, 30 °, 40 °, and 50 °, the difference from the R / d of φ = 0 ° was obtained, and these were further divided by sin2r (r: refraction angle). The birefringence ΔNyz at each φ was obtained, and the positive and negative signs were reversed to obtain the birefringence value ΔNyz. The birefringence value ΔNyz was calculated as the average value of ΔNyz at φ = 20 °, 30 °, 40 °, and 50 °.
Next, the birefringence value ΔNxz was calculated by dividing ΔNzy obtained above from the value obtained by dividing the retardation value R measured at the inclination angle φ = 0 ° by the thickness d.
Finally, the birefringence values ΔNyz and ΔNxz were substituted into the equation: ΔP = (ΔNyz + ΔNxz) / 2 to determine ΔP. The value of the refraction angle r at each inclination angle φ of polypropylene used was that described on page 109 of the aforementioned non-patent document. Table 2 shows the results.

<Rate of increase of tan δ before and after thermal shock test and change rate of capacitance>
[Preparation of capacitor]
The metal layer-integrated polypropylene films prepared in Examples and Comparative Examples were slit to a width of 60 mm. Next, two metal layer-integrated polypropylene films were combined. Using the automatic winding machine 3KAW-N2 manufactured by Minato Manufacturing Co., Ltd., the combined polypropylene layer with metal layer was wound for 1,137 turns at a winding tension of 250 g, a contact pressure of 880 g, and a winding speed of 4 m / s. Was done. The wound element was subjected to a heat treatment at 120 ° C. for 15 hours while being pressed under a load of 5.9 kg / cm ² . Thereafter, zinc metal was sprayed on the end face of the element. The spraying was performed under the conditions of a feed rate of 15 mm / s, a spraying voltage of 22 V, a spraying pressure of 0.3 MPa, and a thickness of 0.7 mm. Thus, a flat capacitor was obtained. A lead wire was soldered to the end face of the flat type capacitor. Then, the flat type capacitor was sealed with epoxy resin. The epoxy resin was cured by heating at 90 ° C. for 2.5 hours and further heating at 120 ° C. for 2.5 hours. The capacitance of the completed capacitor was 75 μF.

[Method of thermal shock test]
The above-prepared capacitor for measurement was put into a thermal shock test apparatus (Espec TSA-101S-W), and a cycle of rapid temperature rise and fall between the lower limit temperature of −40 ° C. and the upper limit temperature of 105 ° C. was repeated 500 times. Specifically, holding at -40.degree. C. for 50 minutes and holding at 105.degree. C. for 50 minutes were set as one set and repeated 500 times. The temperature was switched by blowing air at a set temperature and forcibly changing the temperature. The temperature switching time was also included in the 50-minute holding time.

[Measurement of tan δ and capacitance before and after thermal shock test]
For the produced capacitor element, tan δ and capacitance before and after the thermal shock test were measured using LCR High Tester 3522-50 manufactured by Hioki Electric Co., Ltd. As the test fixture, a four-terminal probe 9140 was used. Specific measurement conditions were an applied voltage of 0.1 V and a frequency of 1 kHz. The measurement was performed for three capacitor elements, and the average value was used as the measured value.
Thereafter, the rate of increase of tan δ was determined by the following equation.
(Increase rate of tan δ) = [[(tan δ after thermal shock test) − (tan δ before thermal shock test)] / (tan δ before thermal shock test)] × 100 (%)
Further, the rate of change of the capacitance was determined by the following equation.
(Change rate of capacitance) = [[(Capacitance after thermal shock test) − (Capacitance before thermal shock test)] / (Capacitance before thermal shock test)] × 100 (%)
Table 2 shows the results.

[Evaluation]
When the rate of increase of the tan δ is 100% or less, it can be said that peeling of the metallikon electrode can be more suitably suppressed. That is, when the metallikon electrode peels off, tan δ increases due to an increase in resistance due to the limitation of the current path, but if the rate of increase of the tan δ is 100% or less, the metallikon electrode It can be guessed that no large peeling has occurred. Therefore, the case where the increase rate of the tan δ was 100% or less was evaluated as A, and the case where the increase rate was larger than 100% was evaluated as B. Table 2 shows the results.

Here, even if the metallikon electrode is largely peeled off, the capacitance does not change so much as long as an electrical connection is obtained. On the other hand, if the capacitance has changed significantly before and after the thermal shock test, a failure other than the metallikon electrode peeling (for example, a failure of the metal layer) has occurred.
In Comparative Example 1-4, the rate of change of the capacitance was in the range of −1.0% or more and 1.0% or less, and it is presumed that no problem other than the peeling of the metallikon electrode occurred. Therefore, in Comparative Example 1-4, it is inferred that the increase in tan δ is certainly caused by the separation of the metallikon electrode, and not caused by a defect other than the separation of the metallikon electrode.

<MD dimensional change at 120 ° C.>
The dimensional change rate in the MD direction was determined by temperature modulation TMA measurement using a thermomechanical analyzer (“SS-6000” manufactured by Seiko Instruments Inc.).
Strips were cut out from the metal layer-integrated polypropylene films prepared in Examples and Comparative Examples so as to have a width of 30 mm in the measurement direction and a width of 4 mm in the direction perpendicular to the measurement direction, thereby preparing samples. Three measurement samples were prepared. At this time, the sample was cut out so that the measurement direction of the sample coincided with the MD direction. The measurement conditions were as follows: the distance between the chucks was 15 mm, the measurement temperature range was 25 ° C. to 150 ° C., the heating rate was 10 ° C./min, and the tensile load applied to the sample piece was 20 mN. From the distance (mm) between the chucks when the furnace temperature reached 120 ° C., the dimensional change rate in the MD direction was determined using the following equation.
[Dimension change rate in MD direction at 120 ° C. (%)] = [(distance between chucks at 120 ° C.−distance between chucks at 25 ° C.) / Distance between chucks at 25 ° C.] × 100
The average value of the three measured values was defined as the dimensional change (%) in the MD direction at 120 ° C.
The dimensional change rate is positive (plus) when the film size increases (expands) with increasing temperature, and negative (minus) when the film size decreases (shrinks) with increasing temperature. Become. Table 2 shows the results.

The embodiments according to the present invention (the first present invention and the second present invention) have been described above.

DESCRIPTION OF SYMBOLS 1 Metal layer integral type polypropylene film 2 Polypropylene film 3 Metal deposition electrode 3a Metal deposition layer 3b Electrode extraction part 4 Insulation margin

Claims

A polypropylene film,
A metal layer-integrated polypropylene film having a metal layer laminated on one side or both sides of the polypropylene film,
When the heat shrinkage in the first direction of the polypropylene film before laminating the metal layer is A, and the heat shrinkage in the first direction of the metal film integrated with the polypropylene is B, the heat shrinkage A and the heat shrinkage A heat-shrinkage ratio [(heat-shrinkage B) / (heat-shrinkage A)] with respect to a ratio B of 0.25 or more and 0.60 or less.
The metal layer-integrated polypropylene film according to claim 1, wherein the heat shrinkage A in the first direction of the polypropylene film before laminating the metal layer is 2.0% or more and 10.0% or less. .
3. The metal layer-integrated polypropylene film according to claim 1, wherein the dimensional change rate in the first direction at 120 ° C. is −0.40% or more.
金属 The metal layer-integrated polypropylene film according to any one of claims 1 to 3, wherein the polypropylene film has a plane orientation coefficient ΔP of 0.010 to 0.016.
(5) The metal layer-integrated polypropylene film according to any one of (1) to (4), which is used for a capacitor.
金属 The metal layer-integrated polypropylene film according to any one of claims 1 to 5, wherein the polypropylene film is biaxially stretched.
It has the metal layer-integrated polypropylene film according to any one of claims 1 to 6 wound, or a plurality of the metal layer-integrated polypropylene films according to any one of claims 1 to 6 are laminated. A film capacitor characterized by having a configuration as described above.
Step A of preparing a polypropylene film,
A method for producing a metal layer-integrated polypropylene film, comprising: laminating a metal layer on one or both surfaces of the polypropylene film prepared in the step A to obtain a metal layer-integrated polypropylene film,
When the heat shrinkage in the first direction of the polypropylene film prepared in the step A is A, and the heat shrinkage B in the first direction of the metal layer-integrated polypropylene film obtained in the step B is A, the heat shrinkage A A heat-shrinkage ratio [(heat-shrinkage B) / (heat-shrinkage A)] of the heat-shrinkage ratio B to the heat-shrinkage ratio B is 0.25 or more and 0.60 or less. Method.
9. The metal layer-integrated polypropylene film according to claim 8, wherein the polypropylene film prepared in the step A has a heat shrinkage A in the first direction of 2.0% or more and 10.0% or less. Production method.