Polypropylene film, metal layer integrated polypropylene film, film capacitor and film roll

Abstract

The present invention relates to a polypropylene film, a metal layer integrated polypropylene film, a film capacitor and a film roll. The polypropylene film is characterized in that it has a first surface and a second surface and contains a polypropylene resin as a main component, and the elliptical density D of the first surface is A 85~120 pieces / mm 2 , the ellipse density D of the second surface B 1~12 pieces / mm 2 .

Description

[0001] This application is a divisional application of an application with a filing date of December 26, 2018, an application number of 201880083593.9, and an invention name of “Polypropylene film, metal layer integrated polypropylene film, film capacitor and film roll”. Technical Field

[0002] The present invention (first invention, second invention and third invention) relates to a polypropylene film, a metal layer integrated polypropylene film, a film capacitor and a film roll. Background Art

[0003] Polypropylene film has excellent electrical properties such as high voltage resistance and low dielectric loss characteristics, and has high moisture resistance. Therefore, it is widely used in electronic equipment and electrical equipment. Specifically, for example, it can be used as a film used in high-voltage capacitors, various switching power supplies, filter capacitors (such as converters, inverters, etc.), smoothing capacitors, etc.

[0004] In recent years, capacitors have been required to be more compact and have a higher capacitance. In order to improve the capacitance without changing the volume of the capacitor, it is preferred to thin the film used as the dielectric. Therefore, thinner films are sought.

[0005] However, thinner polypropylene films are prone to wrinkles and winding deviations during the winding process of components when manufacturing capacitors. Therefore, in order to improve the sliding properties during the winding process of components and facilitate the winding process of the components, fine concave-convex surfaces are sometimes formed on the surface of the polypropylene film to roughen it.

[0006] Patent Document 1 discloses a biaxially stretched polypropylene film for capacitors having a thickness of 1 to 3 μm. When one film surface is designated as surface A and the other surface is designated as surface B, the protrusions on surface A are 2 Number of protrusions (Pa) on the B surface per 0.1 mm 2 The number of particles (Pb), the 10-point average roughness of surface A (SRzA), and the 10-point average roughness of surface B (SRzB) satisfy a prescribed relationship (see claim 1).

[0007] Patent Document 1 states that the biaxially stretched polypropylene film for capacitors of the above structure has excellent processing suitability even if it is a thin film, and exhibits high withstand voltage under a wide range of atmospheric temperature conditions from low temperature (-40°C) to high temperature (150°C) (see paragraph

[0023] ). Regarding processing suitability, specifically, it is stated that the occurrence rate of wrinkles and misalignments is low during element winding processing (see paragraphs

[0122] and

[0123] ).

[0008] Patent Document 2 discloses a biaxially oriented polypropylene film having protrusions on both sides of the film, wherein the height (PhZ) of the largest protrusion among the protrusions on each side is 100 nm or more and less than 400 nm on both sides, and each side has a protrusion height of 0.1 mm. 2 The number of protrusions (Pc) on both sides is 150 or more and less than 500 (see claim 1).

[0009] Patent Document 2 states that, as an effect of the biaxially oriented polypropylene film of the above structure, the film has a surface with many low protrusions on both sides, thereby having high voltage resistance, suitable element processability and excellent chirping characteristics, especially for AC voltage capacitor applications (see paragraph

[0025] ). Regarding element processability, specifically, it is stated that the occurrence rate of wrinkles and misalignments is low during element winding processing (see paragraphs

[0098] and

[0099] ).

[0010] Prior art literature

[0011] Patent Literature

[0012] Patent Document 1: International Publication No. 2013 / 146367

[0013] Patent Document 2: International Publication No. 2012 / 002123 Summary of the invention

[0014] Problem that the invention aims to solve

[0015] For the polypropylene film for capacitors, there is also a step of winding into a roll in its manufacturing process before winding the element for making capacitors. Specifically, in the process of biaxially stretching the unstretched cast sheet, the biaxially stretched polypropylene film is temporarily wound into a roll. Furthermore, the polypropylene film wound into a roll in the above process is unwound (unwound), and a metal layer such as a vapor-deposited film is formed on one side, and then wound again.

[0016] <Topic 1>

[0017] The inventors of the present invention have conducted in-depth research on polypropylene films for capacitors. As a result, they have obtained the following insights: even when a polypropylene film with a roughened surface is used to improve the sliding property during the winding process of the element, when the film with the above-mentioned metal layer is unwound, the vapor-deposited surface and the non-vapor-deposited surface will stick together, and wrinkles in the flow direction may sometimes occur on the film. It should be noted that in this specification, sticking refers to the situation where the polypropylene film of the upper layer and the polypropylene film of the lower layer, which are wound and in contact, are tightly attached under the pressure of winding, etc.

[0018] The first present invention is made in view of the above-mentioned problems, and its purpose is to provide a polypropylene film that can suppress the sticking of a metal layer integrated polypropylene film wound into a roll. In addition, the first present invention provides a metal layer integrated polypropylene film having the polypropylene film, a film capacitor having the metal layer integrated polypropylene film, and a film roll wound into a roll of the polypropylene film.

[0019] <Topic 2>

[0020] The inventors of the present invention have conducted in-depth research on polypropylene films for capacitors. As a result, the following insights were obtained: even when a polypropylene film with a roughened surface is used to improve the sliding property during the winding process of the element, when the film formed with the above-mentioned metal layer is unwound, the vapor-deposited surface and the non-vapor-deposited surface will stick to each other, and wrinkles in the flow direction may sometimes be generated in the film. It should be noted that, in this specification, adhesion refers to the situation where the upper polypropylene film that is wound and in contact with the lower polypropylene film is tightly attached under the pressure of winding, etc. In addition, the following insights were obtained: when the polypropylene film is rolled up and slit after metal vapor deposition, the end face misalignment (the length of the misalignment when the film meanders to the left and right during winding and the end face of the small roll becomes uneven) sometimes becomes larger.

[0021] The second present invention is made in view of the above-mentioned problems, and its purpose is to provide: a polypropylene film that can suppress the adhesion of a metal layer integrated polypropylene film wound into a roll. In addition, the second present invention provides: a metal layer integrated polypropylene film having the polypropylene film, a film capacitor having the metal layer integrated polypropylene film, and a film roll wound into a roll of the polypropylene film. In addition, the second present invention is further preferably based on the above-mentioned purpose, and also provides: a polypropylene film with excellent processability in the slitting process, a metal layer integrated polypropylene film having the polypropylene film, a film capacitor having the metal layer integrated polypropylene film, and a film roll wound into a roll of the polypropylene film.

[0022] <Topic 3>

[0023] The inventors of the present invention have conducted in-depth research on polypropylene films for capacitors. As a result, they have obtained the following insights: even when a polypropylene film with a roughened surface is used to improve the sliding property during the winding process of the element, when the film with the above-mentioned metal layer is unwound, the vapor-deposited surface and the non-vapor-deposited surface will stick together, and wrinkles in the flow direction may sometimes occur in the film. It should be noted that in this specification, sticking refers to the situation where the polypropylene film of the upper layer and the polypropylene film of the lower layer that are wound and in contact are tightly attached under the pressure of winding, etc.

[0024] The third invention is made in view of the above-mentioned problems, and its purpose is to provide a polypropylene film that can suppress the sticking of the metal layer integrated polypropylene film wound into a roll. In addition, the third invention provides a metal layer integrated polypropylene film having the polypropylene film, a film capacitor having the metal layer integrated polypropylene film, and a film roll wound into a roll of the polypropylene film.

[0025] Solutions for solving problems

[0026] <First Invention>

[0027] The present inventors have conducted intensive studies based on the above findings in order to solve the first problem. As a result, they have found that the blocking of a polypropylene film wound into a roll can be suppressed by adopting the following configuration, thereby completing the first present invention.

[0028] The first polypropylene film of the present invention is characterized in that

[0029] has a first side and a second side, and

[0030] Contains polypropylene resin as the main component,

[0031] The Svk value of the first surface (Svk A ) is 0.005 μm or more and 0.030 μm or less,

[0032] The Spk value of the first surface (Spk A ) is greater than 0.035 μm and less than 0.080 μm,

[0033] The Svk value of the second surface (Svk B ) is 0.005 μm or more and 0.030 μm or less,

[0034] The Spk value of the second side (Spk B ) is greater than or equal to 0.015 μm and less than or equal to 0.035 μm.

[0035] Here, the Svk value and the Spk value are parameters defined by the surface property parameter (ISO 25178-2: 2007). The Svk value refers to the average height of the protruding valleys located below the curve obtained by removing the protruding hills and valleys from the load curve. The Spk value refers to the average height of the protruding hills located above the curve obtained by removing the protruding hills and valleys from the load curve.

[0036] When a metal layer is formed on one or both of the first and second surfaces and the film is wound, the first surface of the polypropylene film and the second surface are in contact with each other in a state where the metal layer is formed. A), the Spk value of the first side (Spk A ), the Svk value of the second surface (Svk B ) and the Spk value of the second side (Spk B ) is within the above numerical range, both sides of the polypropylene film are roughened. In addition, under the premise that both sides are roughened, the degree of roughening is different within the above numerical range. Therefore, the contact area between the first side and the second side when the polypropylene film is wound is reduced, and the pores between the first side and the second side generated by the appropriate thick protrusions can be maintained, and the cushioning property is excellent. As a result, it can be seen from the embodiment that adhesion can be suppressed.

[0037] In addition, the polypropylene film is usually wound as follows: in order to prevent wrinkles or meandering, multiple conveying rollers are used while applying tension to the polypropylene film. Therefore, the film is wound while both surfaces are in contact with any conveying roller, not just one surface.

[0038] According to the above configuration, both sides of the polypropylene film are roughened, so when the biaxially stretched polypropylene film is wound into a roll, both sides are suitable for sliding on the conveying roller. As a result, suitable conveying performance can be obtained, wrinkles and winding deviations are suppressed, and the element winding processability becomes good.

[0039] Here, if only the transportability is considered, it is preferable that the roughening degree is the same on the first and second surfaces. However, if the withstand voltage is considered, it is preferable that the roughening degree is different on the first and second surfaces. This point will be described below.

[0040] Generally, for the thickness of the film, when there are uneven surfaces on the surface, the apex of the convex portion is the end of the thickness. That is, when there are uneven surfaces on both the first and second surfaces, the distance from the apex of the convex portion on the first surface to the apex of the convex portion on the second surface is the thickness of the film.

[0041] Here, the thickness of the core portion is the thickness obtained by deducting the height of the convex portion on the first surface and the height of the convex portion on the second surface. Therefore, if a polypropylene film with both surfaces being roughened is formed, the thickness of the core portion becomes thinner, leakage current becomes more likely to occur, and the withstand voltage becomes lower.

[0042] Therefore, in the first present invention, the following is made: (1) For the Svk value (Svk A ) and the Svk value of the second surface (Svk B ) is of the same degree, that is, for the depth of the valley, the first surface and the second surface are appropriately roughened to the same degree, and (2) for the coarse protrusions, the Spk value (Spk B ) is less than the Spk value of the first side (SpkA ) to ensure the thickness of the core. Based on the above, the voltage resistance is maintained and the transport performance based on the roughening is also achieved.

[0043] As described above, according to the first present invention, sticking can be suppressed, and further, both transportability and voltage resistance can be achieved.

[0044] The polypropylene film having the above-mentioned structure is preferably used for capacitors.

[0045] The Spk value of the first side (Spk A ), the Spk value of the first side (Spk A ), the Svk value of the second surface (Svk B ) and the Spk value of the second side (Spk B ) The polypropylene film within the aforementioned numerical range can inhibit adhesion and, further, can have both transportability and voltage resistance, and therefore, can be suitable for use as a capacitor.

[0046] The polypropylene film having the above-mentioned structure is preferably obtained by biaxial stretching.

[0047] If biaxial stretching is performed, it is easy to form a Spk value (Spk A ), the Spk value of the first side (Spk A ), the Svk value of the second surface (Svk B ) and the Spk value of the second side (Spk B ) is a polypropylene film within the aforementioned numerical range.

[0048] The polypropylene film of the above-mentioned structure is preferably such that the Sq value (Sq B ) and the Sq value of the first surface (Sq A ) ratio Sq B / Sq A It is 0.4~1.0.

[0049] Here, the Sq value is a parameter defined in the surface texture parameter (ISO 25178-2: 2007), and is a root mean square value of height data in a defined area.

[0050] The aforementioned ratio Sq B / Sq A If the ratio is 0.4 to 1.0, the dielectric breakdown strength can be maintained and the sticking after the metal layer is formed can be suppressed. This is preferable because it contributes to the suppression of wrinkles when the metal layer is unwound in the subsequent slitting process.

[0051] The polypropylene film of the above-mentioned structure is preferably such that the Sa value (Sa B ) and the Sa value of the first surface (Sa A ) ratio Sa B / Sa A It is 0.6~1.0.

[0052] Here, the Sa value is a parameter defined in the surface texture parameter (ISO 25178-2: 2007), and is the arithmetic mean of the absolute values ​​of height data in a defined area.

[0053] The aforementioned ratio Sa B / Sa A If it is 0.6 to 1.0, the amount of air accompanying the film as it travels is close on the front and back sides. As a result, the film meandering is suppressed, which is related to the suppression of end surface displacement of small rolls in the slitting process of the metal layer integrated film, so it is preferred.

[0054] In the polypropylene film of the above constitution,

[0055] The aforementioned polypropylene resin preferably comprises:

[0056] The linear polypropylene resin A, in the molecular weight differential distribution curve, is obtained by subtracting the differential distribution value when Log(M)=6.0 from the differential distribution value when the logarithmic molecular weight Log(M)=4.5 (the difference when the differential distribution value when Log(M)=6.0 is set as 100% (base), hereinafter also referred to as "differential distribution value difference D M ”) is 8.0% or more;

[0057] The linear polypropylene resin B, in the molecular weight differential distribution curve, is obtained by subtracting the differential distribution value when Log(M)=6.0 from the differential distribution value when the logarithmic molecular weight Log(M)=4.5 (differential distribution value difference D M ) is less than 8.0%; and,

[0058] The long-chain branched polypropylene resin C is obtained by polymerization using a metallocene catalyst.

[0059] The inclusion of a linear polypropylene resin A and a linear polypropylene resin B having different differential distribution values ​​means that two linear polypropylene resins having different amounts of high molecular weight components and low molecular weight components are included. Therefore, the unstretched polypropylene film (cast sheet) containing the linear polypropylene resin A and the linear polypropylene resin B is in a finely mixed state (phase separation state). By stretching such an unstretched polypropylene film, the configuration of the resin components constituting the film becomes complicated, so it is considered that the withstand voltage at high temperature is improved compared to the case of using only one linear polypropylene resin.

[0060] The present inventors have found that, when a long-chain branched polypropylene resin C obtained by polymerization using a metallocene catalyst is included, a large amount of β crystals are formed in the above-mentioned specific cast sheet. Furthermore, by stretching the cast sheet containing β crystals, the β crystals are transformed into α crystals, and therefore, (substantially) arc-shaped irregularities are formed in the polypropylene film obtained by stretching due to the difference in density between β crystals and α crystals, and the surface can be suitably roughened.

[0061] It should be noted that, in addition to the linear polypropylene resin A and the linear polypropylene resin B having different differential distribution values, a long-chain branched polypropylene resin C obtained by polymerization using a metallocene catalyst is also included, thereby improving the voltage resistance of the stretched film caused by the complexity of the configuration of the resin components constituting the film, and forming micronized (roughly) arc-shaped concavities and convexities, which can achieve more suitable roughening.

[0062] In this way, if the linear polypropylene resin A, the linear polypropylene resin B, and the long-chain branched polypropylene resin C are contained in the polypropylene film, the withstand voltage at high temperature can be made more suitable, and more suitable roughening can be achieved.

[0063] It should be noted that, if a long-chain branched polypropylene resin obtained by crosslinking modification of peroxide is used instead of a long-chain branched polypropylene resin C obtained by polymerization using a metallocene catalyst, then based on the α crystal nucleation effect possessed by the long-chain branched polypropylene resin obtained by crosslinking modification of peroxide, the formation of α crystals in the casting sheet is promoted, and the formation of β crystals is greatly suppressed. Even if the casting sheet containing α crystals is stretched, the transformation of crystallites is not caused, and therefore, it is difficult to form concavoconvex. Therefore, in order to roughen the polypropylene film, the long-chain branched polypropylene resin C obtained by polymerization using a metallocene catalyst is suitable.

[0064] Furthermore, the metal layer integrated polypropylene film of the first present invention is characterized by having:

[0065] The aforementioned polypropylene film; and,

[0066] A metal layer laminated on one or both sides of the polypropylene film.

[0067] According to the above configuration, the metal layer is laminated on one or both sides of the polypropylene film, so it can be used for a film capacitor with the polypropylene film as a dielectric and the metal layer as an electrode. In addition, the adhesion of the polypropylene film is suppressed, and further, it can have both transportability and voltage resistance. Therefore, a metal layer integrated polypropylene film with the polypropylene film can be suitably manufactured, and has voltage resistance.

[0068] The film capacitor of the first present invention is characterized by comprising the metal layer integrated polypropylene film wound, or having a structure in which a plurality of metal layer integrated polypropylene films are stacked.

[0069] Furthermore, the film roll according to the first present invention is characterized in that it is obtained by winding the polypropylene film in a roll shape.

[0070] The first present invention has been described above.

[0071] <Second Invention>

[0072] The inventors of the present invention have conducted in-depth research on the above-mentioned viewpoints in order to solve the second problem. As a result, it was found that the following structure can suppress the sticking of the polypropylene film wound into a roll, and the second present invention has been completed. In addition, it was found that the following structure can be used as a preferred case, and the processability of the slitting process is also excellent.

[0073] The polypropylene film of the second invention is characterized in that

[0074] has a first side and a second side, and

[0075] Contains polypropylene resin as the main component,

[0076] The Spk value of the second side (Spk B ) and the Spk value (Spk A ) ratio Spk B / Spk A is 0.490 or more and 0.730 or less,

[0077] The Svk value of the second surface (Svk B ) and the Svk value of the first surface (Svk A ) ratio Svk B / Svk A It is 0.735 or more and 1.250 or less.

[0078] Here, the Svk value and the Spk value are parameters defined in the surface property parameter (ISO 25178-2: 2007). The Svk value refers to the average height of the protruding valleys below the curve obtained by removing the protruding hills and valleys from the load curve. The Spk value refers to the average height of the protruding hills above the curve obtained by removing the protruding hills and valleys from the load curve.

[0079] When a metal layer is formed on one or both of the first and second surfaces and the film is wound, the first surface of the polypropylene film and the second surface are in contact with each other in a state where the metal layer is formed.A ), the Spk value of the first side (Spk A ), the Svk value of the second surface (Svk B ) and the Spk value of the second side (Spk B ) is within the above numerical range, so that the degree of roughening is different within the above numerical range. Therefore, the contact area between the first surface and the second surface when the polypropylene film is wound is reduced, and the pores between the first surface and the second surface generated by the appropriate coarse protrusions can be maintained, and the cushioning property is excellent. As a result, it can be seen from the embodiment that adhesion can be suppressed. In addition, according to the above configuration, as a preferred case, the processability of the slitting process is also excellent.

[0080] In addition, the polypropylene film is usually wound as follows: in order to prevent wrinkles or meandering, multiple conveying rollers are used while applying tension to the polypropylene film. Therefore, the film is wound while both surfaces are in contact with any conveying roller, not just one surface.

[0081] According to the above configuration, both sides of the polypropylene film are roughened to the same extent, so when the biaxially stretched polypropylene film is wound into a roll, both sides are suitable for sliding on the conveying roller. As a result, suitable conveying performance can be obtained, wrinkles and winding deviations are suppressed, and component winding processability becomes good.

[0082] Here, if only the transportability is considered, it is preferable that the roughening degree is the same on the first and second surfaces. However, if the withstand voltage is considered, it is preferable that the roughening degree is different on the first and second surfaces. This point will be described below.

[0083] Generally, for the thickness of the film, when there are uneven surfaces on the surface, the apex of the convex portion is the end of the thickness. That is, when there are uneven surfaces on both the first and second surfaces, the distance from the apex of the convex portion on the first surface to the apex of the convex portion on the second surface is the thickness of the film.

[0084] Here, the thickness of the core portion is the thickness obtained by deducting the height of the convex portion on the first surface and the height of the convex portion on the second surface. Therefore, if a polypropylene film with both surfaces being roughened is formed, the thickness of the core portion becomes thinner, leakage current becomes more likely to occur, and the withstand voltage becomes lower.

[0085] Therefore, in the second present invention, the following is made: (1) For the Svk value (Svk A ) and the Svk value of the second surface (Svk B ) are equal, that is, the depth of the valley is equal on the first and second surfaces, (2) for the large protrusions, the Spk value (Spk) of the second surface is set to B) is less than the Spk value of the first side (Spk A ) to ensure the thickness of the core. Based on the above, the voltage resistance is maintained and the transport performance based on the roughening is also achieved.

[0086] As described above, according to the second present invention, sticking can be suppressed, and further, processability in the slitting process, conveyability, and voltage resistance can be achieved at the same time.

[0087] The polypropylene film having the above-mentioned structure is preferably used for capacitors.

[0088] The Spk value of the first side (Spk A ), the Spk value of the first side (Spk A ), the Svk value of the second surface (Svk B ) and the Spk value of the second side (Spk B ) The polypropylene film within the aforementioned numerical range can inhibit adhesion and, further, can combine slitting process processability, transportability and voltage resistance, and therefore, can be suitable for use as a capacitor.

[0089] The polypropylene film having the above-mentioned structure is preferably obtained by biaxial stretching.

[0090] If biaxial stretching is performed, it is easy to form a Spk value (Spk A ), the Spk value of the first side (Spk A ), the Svk value of the second surface (Svk B ) and the Spk value of the second side (Spk B ) is a polypropylene film within the aforementioned numerical range.

[0091] The polypropylene film of the above-mentioned structure is preferably such that the Sq value (Sq B ) and the Sq value of the first surface (Sq A ) ratio Sq B / Sq A It is 0.4~1.0.

[0092] Here, the Sq value is a parameter defined in the surface texture parameter (ISO 25178-2: 2007), and is a root mean square value of height data in a defined area.

[0093] The aforementioned ratio Sq B / Sq A If the ratio is 0.4 to 1.0, the dielectric breakdown strength can be maintained and the sticking after the metal layer is formed can be suppressed. This is preferable because it contributes to the suppression of wrinkles when the metal layer is unwound in the subsequent slitting process.

[0094] The polypropylene film of the above-mentioned structure is preferably such that the Sa value (Sa B ) and the Sa value of the first surface (SaA ) ratio Sa B / Sa A It is 0.6~1.0.

[0095] Here, the Sa value is a parameter defined in the surface texture parameter (ISO 25178-2: 2007), and is the arithmetic mean of the absolute values ​​of the height data in a defined area.

[0096] The aforementioned ratio Sa B / Sa A If it is 0.6 to 1.0, the amount of air accompanying the film as it travels is close on the front and back sides. As a result, the film meandering is suppressed, which is related to the suppression of end surface displacement of small rolls in the slitting process of the metal layer integrated film, so it is preferred.

[0097] In the polypropylene film of the above constitution,

[0098] The aforementioned polypropylene resin preferably comprises:

[0099] The linear polypropylene resin A, in the molecular weight differential distribution curve, is obtained by subtracting the differential distribution value when Log(M)=6.0 from the differential distribution value when the logarithmic molecular weight Log(M)=4.5 (the difference when the differential distribution value when Log(M)=6.0 is set as 100% (base), hereinafter also referred to as "differential distribution value difference D M ”) is 8.0% or more;

[0100] The linear polypropylene resin B, in the molecular weight differential distribution curve, is obtained by subtracting the differential distribution value when Log(M)=6.0 from the differential distribution value when the logarithmic molecular weight Log(M)=4.5 (differential distribution value difference D M ) is less than 8.0%; and,

[0101] The long-chain branched polypropylene resin C is obtained by polymerization using a metallocene catalyst.

[0102] The linear polypropylene resin A and the linear polypropylene resin B having different differential distribution values ​​refer to two linear polypropylene resins having different amounts of high molecular weight components and low molecular weight components. Therefore, the unstretched polypropylene film (cast sheet) containing the linear polypropylene resin A and the linear polypropylene resin B is in a finely mixed state (phase separation state). Since the configuration of the resin components constituting the film is complicated by stretching such an unstretched polypropylene film, it is considered that the withstand voltage at high temperature is improved compared with the case of using only one linear polypropylene resin.

[0103] The present inventors have found that, when a long-chain branched polypropylene resin C obtained by polymerization using a metallocene catalyst is included, a large amount of β crystals are formed in the above-mentioned specific cast sheet. Furthermore, it has been found that, by stretching a cast sheet containing β crystals, β crystals are converted into α crystals, and therefore, (substantially) arc-shaped irregularities are formed in the polypropylene film obtained by stretching due to the difference in density between β crystals and α crystals, and the surface can be suitably roughened.

[0104] It should be noted that, in addition to the linear polypropylene resin A and the linear polypropylene resin B having different differential distribution values, a long-chain branched polypropylene resin C obtained by polymerization using a metallocene catalyst is also included, thereby improving the voltage resistance of the stretched film caused by the complexity of the configuration of the resin components constituting the film, and forming micronized (roughly) arc-shaped concavities and convexities, which can achieve more suitable roughening.

[0105] In this way, if the linear polypropylene resin A, the linear polypropylene resin B, and the long-chain branched polypropylene resin C are contained in the polypropylene film, the withstand voltage at high temperature can be made more suitable, and more suitable roughening can be achieved.

[0106] It should be noted that, if a long-chain branched polypropylene resin obtained by crosslinking modification of peroxide is used instead of a long-chain branched polypropylene resin C obtained by polymerization using a metallocene catalyst, then based on the α crystal nucleation effect possessed by the long-chain branched polypropylene resin obtained by crosslinking modification of peroxide, the formation of α crystals in the casting sheet is promoted, and the formation of β crystals is greatly suppressed. Even if the casting sheet containing α crystals is stretched, the transformation of crystallites is not caused, and therefore, it is difficult to form concavoconvex. Therefore, in order to roughen the polypropylene film, the long-chain branched polypropylene resin C obtained by polymerization using a metallocene catalyst is suitable.

[0107] In addition, the metal layer integrated polypropylene film of the second present invention is characterized by having:

[0108] The aforementioned polypropylene film; and,

[0109] A metal layer laminated on one or both sides of the polypropylene film.

[0110] According to the above configuration, the metal layer is laminated on one or both sides of the polypropylene film, so it can be used for a film capacitor with the polypropylene film as a dielectric and the metal layer as an electrode. In addition, the adhesion of the polypropylene film is suppressed, and further, the slitting process processability, transportability and voltage resistance can be combined. Therefore, a metal layer integrated polypropylene film with the polypropylene film can be suitably manufactured and has voltage resistance.

[0111] A second film capacitor of the present invention is characterized by comprising the metal layer integrated polypropylene film wound, or having a structure in which a plurality of metal layer integrated polypropylene films are stacked.

[0112] Furthermore, the film roll according to the second present invention is characterized in that it is obtained by winding the polypropylene film in a roll shape.

[0113] The second present invention has been described above.

[0114] <Third Invention>

[0115] The present inventors have conducted intensive studies based on the above findings in order to solve the third problem. As a result, they have found that the blocking of a polypropylene film wound into a roll can be suppressed by adopting the following configuration, and have thus completed the third present invention.

[0116] The polypropylene film of the third invention is characterized in that

[0117] has a first side and a second side, and

[0118] Contains polypropylene resin as the main component,

[0119] The ellipse density D of the first surface A 85~120 pieces / mm 2 ,

[0120] The ellipse density D of the second surface mentioned above B 1~12 pieces / mm 2 .

[0121] Both surfaces of the polypropylene film are roughened by crater-like fine irregularities. Figure 1 (a) is a three-dimensional diagram schematically showing arc pit-shaped fine concavoconvexities, Figure 1 (b) is its cross-sectional view, Figure 1 (c) is a longitudinal cross-sectional view of (b) along the line II'. It should be noted that, Figure 1 (a)~ Figure 1 (c) is a schematic diagram for explaining an “ellipse” and does not represent the surface shape of a polypropylene film or the like in Examples described later.

[0122] Most of the arc pit-shaped fine concavoconvexities are observed, for example, by an optical microscope, as two pairs of circular arc shapes or roughly circular arc shapes (hereinafter, the circular arc shape and the roughly circular arc shape are collectively referred to as "(roughly) circular arc shapes") that are bent in opposite directions. When the observed two pairs of (roughly) circular arc shapes are partially supplemented (interpolated) and connected, they become an elliptical shape or a roughly elliptical shape (hereinafter, the elliptical shape and the roughly elliptical shape are collectively referred to as "(roughly) elliptical shapes").

[0123] The two (substantially) arc-shaped portions formed in the pair form a protrusion and a depression between the protrusions (see Figure 1 (a)). The protrusions and depressions form the above-mentioned arc pit-shaped fine concavo-convex (refer to Figure 1 (b) and Figure 1 (c)). It should be noted that the two (roughly) arc shapes sometimes form a circular shape or a roughly circular shape (hereinafter, the circular shape and the roughly circular shape are collectively referred to as "(roughly) circular shape") or a (roughly) elliptical shape. At this time, the cross-section of the protrusion becomes an annular shape or a roughly annular shape (hereinafter, the annular shape and the roughly annular shape are collectively referred to as "(roughly) annular shape") or an elliptical ring shape or a roughly elliptical ring shape (hereinafter, the elliptical ring shape and the roughly elliptical ring shape are collectively referred to as "(roughly) elliptical ring shape"). In addition, it is sometimes observed as a single (roughly) arc shape without a pair.

[0124] The ellipse density is the total count per unit area of ​​the following (X) and the following (Y) observed with a digital oscilloscope (eg, digital microscope VHX-2000 manufactured by Keyence Corporation). Hereinafter, the shape of the following (X) and the shape of the following (Y) are also collectively referred to as "ellipse".

[0125] It should be noted that, when the length of one axis is L μm and the length of the other axis is S μm, those satisfying S ≤ L and 1 ≤ L ≤ 300 are considered as "ellipses" when calculating the ellipse density. Those not satisfying these conditions are not considered when calculating the ellipse density (not counted as "ellipses" when calculating the ellipse density).

[0126] (X) A (substantially) circular shape or a (substantially) elliptical shape formed by the two (substantially) arc-shaped protrusions forming a pair.

[0127] (Y) A (substantially) elliptical shape formed by interpolating and connecting the above-mentioned pair of two (substantially) circular arc shapes.

[0128] The ellipse density D of the first surface A 85~120 pieces / mm 2 , the ellipse density D of the second surface mentioned above B 1~12 pieces / mm 2 Therefore, the contact area between the first surface and the second surface when the polypropylene film is wound becomes small, and the pores between the first surface and the second surface generated by the difference in elliptical density can be maintained, and the cushioning property is excellent. As a result, it can be seen from the examples that blocking can be suppressed.

[0129] In addition, the ellipse density D of the first surface A 85~120 pieces / mm 2, it can be said that the number of "ovals" is large. Therefore, the roughening is performed more. On the other hand, the ellipse density D of the second surface is B 1~12 pieces / mm 2 , it can be said that the number of "ovals" is small. Therefore, although it is roughened, the degree is small.

[0130] In this way, if the ellipse density D of the first surface is A 85~120 pieces / mm 2 , and the ellipse density D of the second surface B 1~12 pieces / mm 2 , it is possible to suppress the film from meandering to the left and right during the slitting process, and the end surface of the small roll becomes uneven. As a result, it is known from the embodiment that the slitting process can be made good in processability.

[0131] In addition, the polypropylene film is usually wound as follows: in order to prevent wrinkles or meandering, multiple conveying rollers are used while applying tension to the polypropylene film. Therefore, the film is wound while both surfaces are in contact with any conveying roller, not just one surface.

[0132] According to the above-mentioned polypropylene film, both sides of the polypropylene film are roughened, so when the biaxially stretched polypropylene film is wound into a roll, both sides are suitable for sliding on the conveying roller. As a result, suitable conveying performance can be obtained, and wrinkles and winding deviations are suppressed.

[0133] Specifically, the ellipse density D of the first surface is A 85~120 pieces / mm 2 , the ellipse density D of the second surface mentioned above B 1~12 pieces / mm 2 Therefore, both sides of the polypropylene film are suitably roughened, so that when the biaxially stretched polypropylene film is wound into a roll, both sides are suitable for sliding on the conveying roller. As a result, suitable conveying performance can be obtained, wrinkles and winding deviations are further suppressed, and the element winding processability becomes good.

[0134] Here, if only the transportability is considered, it is preferable that the roughening degree is the same on the first and second surfaces. However, if the withstand voltage is considered, it is preferable that the roughening degree is different on the first and second surfaces. Generally, if the surface is roughened, the thinner part of the film (the concave part of the concave-convex part) becomes the cause of leakage current. Therefore, if the ellipticity D of the second surface is increased, B Smaller than the ellipse density D of the first surface A , the number of concave and convex surfaces that may cause leakage current can be reduced. Specifically, the ellipse density D of the second surface is B If 1 to 12 pieces / mm2 , it can be said that the number of concavities and convexities that may cause leakage current is small. As a result, the structure is formed to appropriately maintain the withstand voltage and more appropriately have the transport property due to the roughening.

[0135] As described above, according to the third present invention, sticking can be suppressed, and further, processability in the slitting process, conveyability, and voltage resistance can be achieved at the same time.

[0136] The polypropylene film having the above-mentioned structure is preferably used for capacitors.

[0137] Ellipse density D of the first surface A 85~120 pieces / mm 2 , the ellipse density D of the second surface B 1~12 pieces / mm 2 The polypropylene film can suppress adhesion, and furthermore, has both processability in the slitting process and transportability and voltage resistance, and therefore, can be suitably used as a capacitor.

[0138] The polypropylene film having the above-mentioned structure is preferably obtained by biaxial stretching.

[0139] If biaxial stretching is performed, the elliptical density D of the first surface is easily formed. A 85~120 pieces / mm 2 , the ellipse density D of the second surface B 1~12 pieces / mm 2 Polypropylene film.

[0140] The polypropylene film of the above-mentioned structure is preferably such that the elliptical density D constituting the above-mentioned first surface is A The average major axis length L of the ellipse A is 20 to 80 μm, constituting the ellipse density D of the second surface B The average major axis length L of the ellipse B 30~100μm.

[0141] The average major axis length L A is the ellipse density D A The average value of the major axis of the "ellipse" observed in the measurement.

[0142] The average major axis length L B is the ellipse density D B The average value of the major axis of the "ellipse" observed in the measurement.

[0143] The density D of the ellipse constituting the first surface A The average major axis length L of the ellipse A When the value is 20 to 80 μm, it becomes easy to make the ellipticity density D of the first surface AIn addition, the ellipse density D constituting the second surface is B The average major axis length L of the ellipse B When the thickness is 30 to 100 μm, it becomes easy to make the ellipticity D of the second surface B is within the aforementioned numerical range.

[0144] The polypropylene film of the above-mentioned structure is preferably such that the Sq value (Sq B ) and the Sq value of the first surface (Sq A ) ratio Sq B / Sq A It is 0.4~1.0.

[0145] Here, the Sq value is a parameter defined in the surface texture parameter (ISO 25178-2: 2007), and is a root mean square value of height data in a defined area.

[0146] The aforementioned ratio Sq B / Sq A If the ratio is 0.4 to 1.0, the dielectric breakdown strength can be maintained and the sticking after the metal layer is formed can be suppressed. This is preferable because it contributes to the suppression of wrinkles when the metal layer is unwound in the subsequent slitting process.

[0147] The polypropylene film of the above-mentioned structure is preferably such that the Sa value (Sa B ) and the Sa value of the first surface (Sa A ) ratio Sa B / Sa A It is 0.6~1.0.

[0148] Here, the Sa value is a parameter defined in the surface texture parameter (ISO 25178-2: 2007), and is the arithmetic mean of the absolute values ​​of the height data in a defined area.

[0149] The aforementioned ratio Sa B / Sa A If it is 0.6 to 1.0, the amount of air accompanying the film as it travels is close on the front and back sides. As a result, the film meandering is suppressed, which is related to the suppression of end surface displacement of small rolls in the slitting process of the metal layer integrated film, so it is preferred.

[0150] In the polypropylene film of the above constitution,

[0151] The aforementioned polypropylene resin preferably comprises:

[0152] The linear polypropylene resin A, in the molecular weight differential distribution curve, is obtained by subtracting the differential distribution value when Log(M)=6.0 from the differential distribution value when the logarithmic molecular weight Log(M)=4.5 (the difference when the differential distribution value when Log(M)=6.0 is set as 100% (base), hereinafter also referred to as "differential distribution value difference D M ”) is 8.0% or more;

[0153] The linear polypropylene resin B, in the molecular weight differential distribution curve, is obtained by subtracting the differential distribution value when Log(M)=6.0 from the differential distribution value when the logarithmic molecular weight Log(M)=4.5 (differential distribution value difference D M ) is less than 8.0%; and,

[0154] The long-chain branched polypropylene resin C is obtained by polymerization using a metallocene catalyst.

[0155] The linear polypropylene resin A and the linear polypropylene resin B having different differential distribution values ​​refer to two linear polypropylene resins having different amounts of high molecular weight components and low molecular weight components. Therefore, the unstretched polypropylene film (cast sheet) containing the linear polypropylene resin A and the linear polypropylene resin B is in a finely mixed state (phase separation state). The configuration of the resin components constituting the film is complicated by stretching such an unstretched polypropylene film, so it is considered that the withstand voltage at high temperature is improved compared with the case of using only one linear polypropylene resin.

[0156] The present inventors have found that, when a long-chain branched polypropylene resin C obtained by polymerization using a metallocene catalyst is included, a large amount of β crystals are formed in the above-mentioned specific cast sheet. Furthermore, it has been found that, by stretching a cast sheet containing β crystals, β crystals are converted into α crystals, and therefore, (substantially) arc-shaped irregularities are formed in the polypropylene film obtained by stretching due to the difference in density between β crystals and α crystals, and the surface can be suitably roughened.

[0157] It should be noted that, in addition to the linear polypropylene resin A and the linear polypropylene resin B having different differential distribution values, a long-chain branched polypropylene resin C obtained by polymerization using a metallocene catalyst is also included, thereby improving the voltage resistance of the stretched film caused by the complexity of the configuration of the resin components constituting the film, and forming micronized (roughly) arc-shaped concavities and convexities, which can achieve more suitable roughening.

[0158] In this way, if the linear polypropylene resin A, the linear polypropylene resin B, and the long-chain branched polypropylene resin C are contained in the polypropylene film, the withstand voltage at high temperature can be made more suitable, and more suitable roughening can be achieved.

[0159] It should be noted that, if a long-chain branched polypropylene resin obtained by crosslinking modification of peroxide is used instead of a long-chain branched polypropylene resin C obtained by polymerization using a metallocene catalyst, the formation of α crystals in the casting sheet is promoted based on the α crystal nucleation effect of the long-chain branched polypropylene resin obtained by crosslinking modification of peroxide, and the formation of β crystals becomes greatly suppressed. Even if the casting sheet containing α crystals is stretched, the transformation of crystallites is not caused, and therefore, it is difficult to form concavoconvex. Therefore, in order to roughen the polypropylene film, the long-chain branched polypropylene resin C obtained by polymerization using a metallocene catalyst is suitable.

[0160] In addition, the metal layer integrated polypropylene film of the third present invention is characterized by having:

[0161] The aforementioned polypropylene film; and,

[0162] A metal layer laminated on one or both sides of the polypropylene film.

[0163] According to the above configuration, the metal layer is laminated on one or both sides of the polypropylene film, so it can be used for a film capacitor with the polypropylene film as a dielectric and the metal layer as an electrode. In addition, the adhesion of the polypropylene film is suppressed, and further, the slitting process processability, transportability and voltage resistance are combined, so the metal layer integrated polypropylene film with the polypropylene film can be suitably manufactured and has voltage resistance.

[0164] A third aspect of the present invention provides a film capacitor having a wound metal layer-integrated polypropylene film or a structure in which a plurality of metal layer-integrated polypropylene films are stacked.

[0165] Furthermore, the film roll according to the third aspect of the present invention is characterized in that it is obtained by winding the polypropylene film in a roll shape.

[0166] The third present invention has been described above.

[0167] Effects of the Invention

[0168] According to the first present invention, a polypropylene film capable of suppressing the sticking of a metal layer integrated polypropylene film wound into a roll can be provided. In addition, a metal layer integrated polypropylene film having the polypropylene film, a film capacitor having the metal layer integrated polypropylene film, and a film roll obtained by winding the polypropylene film into a roll can be provided.

[0169] According to the second present invention, it is possible to provide: a polypropylene film capable of suppressing the sticking of a metal layer integrated polypropylene film wound into a roll. In addition, it is possible to provide: a metal layer integrated polypropylene film having the polypropylene film and a film capacitor having the metal layer integrated polypropylene film. In addition, according to the second present invention, it is further preferred that, on the basis of the above-mentioned purpose, it is possible to provide: a polypropylene film having excellent processability in a slitting process, a metal layer integrated polypropylene film having the polypropylene film and a film capacitor having the metal layer integrated polypropylene film.

[0170] According to the third present invention, a polypropylene film capable of suppressing the sticking of a metal layer integrated polypropylene film wound into a roll can be provided. In addition, a metal layer integrated polypropylene film having the polypropylene film, a film capacitor having the metal layer integrated polypropylene film, and a film roll obtained by winding the polypropylene film into a roll can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0171] Figure 1 (a) is a three-dimensional diagram schematically showing arc pit-shaped fine concavoconvexities, Figure 1 (b) is its cross-sectional view, Figure 1 (c) is a longitudinal cross-sectional view of (b) along line II'.

[0172] Figure 2 This is a diagram showing an example of a projection image obtained by projecting a portion of fine irregularities having a height of 0.02 μm or more onto a film surface using an optical interference type non-contact surface profile measuring device.

[0173] Figure 3 (a) to (c) are schematic top views for explaining the method of determining the virtual circular ring. DETAILED DESCRIPTION

[0174] Hereinafter, embodiments of the present invention (the first present invention, the second present invention, and the third present invention) will be described. However, the present invention (the first present invention, the second present invention, and the third present invention) is not limited to these embodiments.

[0175] In this specification, the expressions “comprise” and “include” include the concepts of “comprise”, “include”, “consist essentially of”, and “consist only of”.

[0176] In this specification, "element", "capacitor", "capacitor element" and "film capacitor" have the same meaning.

[0177] The biaxially stretched polypropylene film according to the embodiment of the present invention (the first present invention, the second present invention, and the third present invention) is not a microporous film and therefore does not have a large number of pores.

[0178] The biaxially stretched polypropylene film of the embodiment of the present invention (the first present invention, the second present invention, and the third present invention) may be composed of two or more layers, but is preferably composed of a single layer.

[0179] <First embodiment of the present invention>

[0180] Hereinafter, a first embodiment of the present invention will be described.

[0181] A polypropylene film according to a first embodiment of the present invention (hereinafter also referred to as "first embodiment") is characterized in that:

[0182] Contains polypropylene resin as the main component,

[0183] The Svk value of the first surface (Svk A ) is 0.005 μm or more and 0.030 μm or less,

[0184] The Spk value of the first surface (Spk A ) is greater than 0.035 μm and less than 0.080 μm,

[0185] The Svk value of the second surface (Svk B ) is 0.005 μm or more and 0.030 μm or less,

[0186] The Spk value of the second side (Spk B ) is greater than or equal to 0.015 μm and less than or equal to 0.035 μm.

[0187] The Svk value of the first surface (Svk A ) is preferably 0.007 μm or more and 0.025 μm or less, more preferably 0.008 μm or more and 0.020 μm or less, further preferably 0.009 μm or more and 0.015 μm or less.

[0188] The Spk value of the first surface (Spk A ) is preferably 0.040 μm or more and 0.075 μm or less, more preferably 0.043 μm or more and 0.060 μm or less, further preferably 0.045 μm or more and 0.055 μm or less.

[0189] The Svk value of the second surface (Svk B ) is preferably 0.007 μm or more and 0.025 μm or less, more preferably 0.008 μm or more and 0.020 μm or less, further preferably 0.009 μm or more and 0.015 μm or less.

[0190] The Spk value of the second side (Spk B) is preferably 0.017 μm or more and 0.033 μm or less, more preferably 0.018 μm or more and 0.030 μm or less, further preferably 0.020 μm or more and 0.025 μm or less.

[0191] When a metal layer is formed on one or both of the first and second surfaces and the film is wound, the first surface of the polypropylene film and the second surface are in contact with each other in a state where the metal layer is formed. A ), the Spk value of the first side (Spk A ), the Svk value of the second surface (Svk B ) and the Spk value of the second side (Spk B ) is within the above numerical range, and both sides of the polypropylene film are roughened. In addition, under the premise that both sides are roughened, the degree of roughening is different within the above numerical range. Therefore, the contact area between the first side and the second side when the polypropylene film is wound is reduced, and the pores between the first side and the second side generated by the appropriate coarse protrusions can be maintained, and the cushioning property is excellent. As a result, it can be seen from the embodiment that adhesion can be suppressed.

[0192] In addition, the polypropylene film is usually wound as follows: in order to prevent wrinkles or meandering, multiple conveying rollers are used while applying tension to the polypropylene film. Therefore, the film is wound while both surfaces are in contact with any conveying roller, not just one surface.

[0193] According to the polypropylene film, both sides of the polypropylene film are roughened, so when the biaxially stretched polypropylene film is wound into a roll, both sides are suitable for sliding on the conveying roller. As a result, suitable conveying performance can be obtained, wrinkles and winding deviations are suppressed, and the element winding processability becomes good.

[0194] Here, if only the transportability is considered, it is preferable that the roughening degree is the same on the first and second surfaces. However, if the withstand voltage is considered, it is preferable that the roughening degree is different on the first and second surfaces. This point will be described below.

[0195] Generally, for the thickness of the film, when there are uneven surfaces on the surface, the apex of the convex portion is the end of the thickness. That is, when there are uneven surfaces on both the first and second surfaces, the distance from the apex of the convex portion on the first surface to the apex of the convex portion on the second surface is the thickness of the film.

[0196] Here, the thickness of the core portion is the thickness obtained by deducting the height of the convex portion on the first surface and the height of the convex portion on the second surface. Therefore, if a polypropylene film with both surfaces being roughened is formed, the thickness of the core portion becomes thinner, leakage current becomes more likely to occur, and the withstand voltage becomes lower.

[0197] Therefore, in the first embodiment, the following is configured: (1) For the Svk value (Svk A ) and the Svk value of the second surface (Svk B ) is of the same degree, that is, for the depth of the valley, the first surface and the second surface are appropriately roughened to the same degree, and (2) for the coarse protrusions, the Spk value (Spk B ) is less than the Spk value of the first side (Spk A ) to ensure the thickness of the core. Based on the above, the voltage resistance is maintained and the transport performance based on the roughening is also achieved.

[0198] As described above, according to the polypropylene film of the first embodiment, blocking can be suppressed, and further, both conveyability and voltage resistance can be achieved.

[0199] The Svk value of the first surface (Svk A ), the Spk value of the first surface (Spk A ), the Svk value of the second surface (Svk B ) and the Spk value of the second side mentioned above (Spk B ) is obtained as follows: using an optical interference type non-contact surface shape measuring machine, using a three-dimensional surface roughness evaluation method, the surface shape is measured, thereby obtaining. "Three-dimensional surface roughness evaluation method" is to evaluate the height of the entire surface of the film, therefore, the shape of the film surface is evaluated in a three-dimensional manner. Therefore, the local subtle changes and variations of the measured object surface can be grasped, and a more accurate surface roughness can be evaluated. The average height of the three-dimensional protruding mountain portion and the average height of the protruding valley portion are used instead of the height of the simple protrusion (based on the two-dimensional surface roughness evaluation of the general center line average roughness Ra, etc.), the film surface roughness is evaluated, so that adhesion can be suppressed. In addition, a structure with both good transportability and voltage resistance can be formed.

[0200] More specifically, the Svk value (Svk A ), the Spk value of the first surface (Spk A ), the Svk value of the second surface (Svk B ) and the Spk value of the second side mentioned above (Spk B ) is a value measured using "VertScan2.0 (Model: R5500GML)" manufactured by Ryoka Systems Inc. as an optical interference type non-contact surface profile measuring machine.

[0201] The following describes the details of the measurement method.

[0202] First, using the WAVE mode, a 530 white filter and a 1×BODY lens tube, and a ×10 objective lens, measurements of 470.92 μm × 353.16 μm were performed in each field of view. This was performed at 10 locations at 1 cm intervals from the center in the flow direction and width direction of the target sample (polypropylene film) along the flow direction.

[0203] Next, the obtained data was subjected to noise removal processing using a median filter (3×3), and then subjected to Gaussian filter processing using a cutoff value of 30 μm to remove the curvature component. This enabled the roughened surface state to be appropriately measured.

[0204] Next, use the "ISO parameters" in the "bearing" plug-in function of the "VS-Viewer" analysis software of "VertScan2.0" for analysis.

[0205] Finally, for each value (Svk A 、Spk A , Svk B 、Spk B , Sq A , Sq B , Sa A , Sa B ,Sk A ,Sk B ), and calculate the average value respectively. Based on the above, the Svk value (Svk A ), the Spk value of the first surface (Spk A ), the Svk value of the second surface (Svk B ) and the Spk value of the second side mentioned above (Spk B ). In addition, Sq is obtained in the same way. A , Sq B , Sa A , Sa B ,Sk A ,Sk B .

[0206] More specifically, it is based on the method described in Examples.

[0207] For the polypropylene film, the Sq value (Sq B ) and the Sq value of the first surface (Sq A ) ratio Sq B / Sq A It is preferably 0.4 to 1.0, more preferably 0.45 to 0.8, and still more preferably 0.48 to 0.7.

[0208] The aforementioned Sq AIt is preferably 0.020 μm to 0.080 μm, more preferably 0.025 μm to 0.070 μm.

[0209] The aforementioned Sq B It is preferably 0.005 μm to 0.030 μm, more preferably 0.010 μm to 0.025 μm.

[0210] The aforementioned ratio Sq B / Sq A If the ratio is 0.4 to 1.0, the dielectric breakdown strength can be maintained and the sticking after the metal layer is formed can be suppressed. This is preferable because it contributes to the suppression of wrinkles when the metal layer is unwound in the subsequent slitting process.

[0211] The Sq value of the first surface (Sq A ), the Sq value of the second surface (Sq B ), the aforementioned ratio Sq B / Sq A The detailed measurement method is based on the method described in the Examples.

[0212] For the polypropylene film, the Sa value (Sa B ) and the Sa value of the first surface (Sa A ) ratio Sa B / Sa A It is preferably 0.6 to 1.0, more preferably 0.65 to 0.9, and still more preferably 0.7 to 0.8.

[0213] The aforementioned Sa A It is preferably 0.005 μm to 0.025 μm, more preferably 0.009 μm to 0.020 μm.

[0214] The aforementioned Sa B It is preferably 0.005 μm to 0.025 μm, more preferably 0.007 μm to 0.015 μm.

[0215] The aforementioned ratio Sa B / Sa A If it is 0.6 to 1.0, the amount of air accompanying the film as it travels is close at the front and back sides. As a result, the meandering of the film is suppressed, which is related to the suppression of end surface displacement of small rolls in the slitting process of the metal layer integrated film, so it is preferred.

[0216] The Sa value of the first surface (Sa A ), the Sa value of the second surface (Sa B ), the aforementioned ratio Sa B / Sa A The detailed measurement method is based on the method described in the Examples.

[0217] For the polypropylene film, the Sk value (Sk B ) and the Sk value (Sk A ) ratio Sk B / Sk A It is preferably 0.6 to 1.0, more preferably 0.7 to 0.9, and still more preferably 0.75 to 0.85.

[0218] The aforementioned Sk A It is preferably 0.030 μm to 0.070 μm, more preferably 0.035 to 0.060.

[0219] The aforementioned Sk B It is preferably 0.010 μm to 0.050 μm, more preferably 0.020 μm to 0.040 μm.

[0220] Here, the Sk value is a parameter defined by a surface texture parameter (ISO 25178-2:2007), and is the difference between an upper horizontal plane and a lower horizontal plane of a load curve obtained by removing protruding peaks and protruding valleys from the load curve.

[0221] The aforementioned ratio Sk B / Sk A If the ratio is 0.6 to 1.0, the dielectric breakdown strength can be maintained and the sticking after the metal layer is formed can be suppressed. This is preferable because it contributes to the suppression of wrinkles when the metal layer is unwound in the subsequent slitting process.

[0222] The Sk value of the first surface (Sk A ), the Sk value of the second surface (Sk B ), the aforementioned ratio Sk B / Sk A The detailed measurement method is based on the method described in the Examples.

[0223] For the Svk value (Svk A ), the Spk value of the first surface (Spk A ), the Svk value of the second surface (Svk B ), the Spk value of the second surface (Spk B ), the Sq value of the first surface (Sq A ), the Sq value of the second surface (Sq B ), the aforementioned ratio Sq B / Sq A , the Sa value of the first surface (Sa A ), the Sa value of the second surface (Sa B ), the aforementioned ratio Sa B / Sa A , the Sk value of the first surface (SkA ), the Sk value of the second surface (Sk B ) and the aforementioned ratio Sk B / Sk A The method of keeping the above numerical range is not particularly limited, and can be based on (i) the type of resin (raw material resin) constituting the above polypropylene film, stereoregularity, molecular weight distribution and differential distribution value difference D M , (ii) the content of each resin relative to the overall polypropylene film, (iii) the longitudinal and transverse stretching ratios during stretching, and the stretching temperature, (iv) the type of additives (especially nucleating agents) and their content, etc. are appropriately adjusted.

[0224] As the Svk value (Svk A ) and the Svk value of the second surface mentioned above (Svk B ) different methods, so that the Spk value (Spk A ) and the Spk value (Spk B ) different methods, so that the Sq value of the first surface (Sq A ) and the Sq value of the second surface (Sq B ) different methods, so that the Sa value (Sa A ) and the Sa value of the second surface (Sa B ) different methods, making the Sk value (Sk A ) and the Sk value of the second surface (Sk B ) Different methods are not particularly limited, and for example, the adjustment can be made as follows: the first surface is used as the surface on the casting roll side and the second surface is used as the surface on the air knife side to make a casting sheet, and the casting sheet is biaxially stretched to achieve the adjustment.

[0225] Both surfaces of the polypropylene film may be roughened by crater-like fine irregularities. Figure 1 (a) is a three-dimensional diagram schematically showing arc pit-shaped fine concavoconvexities, Figure 1 (b) is its cross-sectional view, Figure 1 (c) is a longitudinal cross-sectional view of (b) along the line II'. It should be noted that, Figure 1 (a)~ Figure 1 (c) is a schematic diagram for explaining an “ellipse” and does not represent the surface shape of a polypropylene film or the like in Examples described later.

[0226] Most of the arc pit-shaped fine concavoconvexities are observed, for example, through an optical microscope, as two pairs of circular arc shapes or approximately circular arc shapes (hereinafter, the circular arc shape and the approximately circular arc shape are collectively referred to as "(approximately) circular arc shapes") that are bent in opposite directions. When the observed two pairs of (approximately) circular arc shapes are partially supplemented (interpolated) and connected, they become an elliptical shape or a substantially elliptical shape (hereinafter, the elliptical shape and the substantially elliptical shape are collectively referred to as "(approximately) elliptical shapes").

[0227] The two (substantially) arc-shaped portions formed in the pair form a protrusion and a depression between the protrusions (see Figure 1 (a)). The protrusions and depressions form the above-mentioned arc pit-shaped fine concavo-convex (refer to Figure 1 (b) and Figure 1 (c)). It should be noted that the two (roughly) arc shapes sometimes form a circular shape or a roughly circular shape (hereinafter, the circular shape and the roughly circular shape are collectively referred to as "(roughly) circular shape") or a (roughly) elliptical shape. At this time, the cross-section of the protrusion becomes an annular shape or a roughly annular shape (hereinafter, the annular shape and the roughly annular shape are collectively referred to as "(roughly) annular shape") or an elliptical ring shape or a roughly elliptical ring shape (hereinafter, the elliptical ring shape and the roughly elliptical ring shape are collectively referred to as "(roughly) elliptical ring shape"). In addition, it is sometimes observed as a single (roughly) arc shape without a pair.

[0228] For the polypropylene film, the elliptical density D of the first surface is preferably A 85~120 pieces / mm 2 , the ellipse density D of the second surface B 1~12 pieces / mm 2 .

[0229] The aforementioned ellipse density D A More preferably 85 to 110 pieces / mm 2 , more preferably 90 to 105 pieces / mm 2 .

[0230] The aforementioned ellipse density D B More preferably, 3 to 11 pieces / mm 2 , more preferably 4 to 10 pieces / mm 2 .

[0231] The ellipse density is the total number of counts per unit area of ​​the following (X) and the following (Y) observed with a digital oscilloscope (eg, digital microscope VHX-2000 manufactured by Keyence Corporation). Hereinafter, the shape of the following (X) and the shape of the following (Y) are also collectively referred to as "ellipse".

[0232] It should be noted that, when the length of one axis is L μm and the length of the other axis is S μm, those satisfying S ≤ L and 1 ≤ L ≤ 300 are considered as "ellipses" when calculating the ellipse density. Those not satisfying these conditions are not considered when calculating the ellipse density (not counted as "ellipses" when calculating the ellipse density).

[0233] (X) A (substantially) circular shape or a (substantially) elliptical shape formed by the two (substantially) arc-shaped protrusions forming a pair.

[0234] (Y) A (substantially) elliptical shape formed by interpolating and connecting the above-mentioned pair of two (substantially) circular arc shapes.

[0235] The specific method for measuring the ellipticity is based on the method described in Examples.

[0236] If the ellipse density D of the first surface A 85~120 pieces / mm 2 , the ellipse density D of the second surface B 1~12 pieces / mm 2 , the contact area between the first surface and the second surface when the polypropylene film is wound can be further reduced.

[0237] Specifically, the ellipse density D of the first surface is A 85~120 pieces / mm 2 In the case of , it can be said that the number of "ellipses" is large. Therefore, the roughening is performed more. On the other hand, the ellipse density D of the second surface is B If 1 to 12 pieces / mm 2 , it can be said that the number of "ovals" is small. Therefore, although it is roughened, the degree is small.

[0238] In this way, if the ellipse density D of the first surface is A 85~120 pieces / mm 2 , and the ellipse density D of the second surface B 1~12 pieces / mm 2 , it is possible to suppress the film from meandering to the left and right during the slitting process, and the end surface of the small roll becomes uneven. As a result, it is known from the embodiment that the slitting process can be made good in processability.

[0239] In addition, if the ellipse density D of the first surface A 85~120 pieces / mm 2 , the ellipse density D of the second surface B 1~12 pieces / mm 2, both sides of the polypropylene film are more appropriately roughened, so when the biaxially stretched polypropylene film is wound into a roll, both sides are more suitable for sliding on the conveying roller. As a result, more suitable conveying performance can be obtained, and wrinkles and winding deviations are further suppressed.

[0240] Here, if only the transportability is considered, it is preferable that the roughening degree is the same on the first and second surfaces. However, if the withstand voltage is considered, it is preferable that the roughening degree is different on the first and second surfaces. Generally, if the surface is roughened, the thinner part of the film (the concave part of the concave-convex part) becomes the cause of leakage current. Therefore, if the ellipticity D of the second surface is increased, B Smaller than the ellipse density D of the first surface A , the number of concave and convex surfaces that may cause leakage current can be reduced. Specifically, the ellipse density D of the second surface is B If 1 to 12 pieces / mm 2 As a result, the structure can more appropriately maintain the withstand voltage and more appropriately have the transport performance due to the roughening.

[0241] The polypropylene film preferably has an elliptical density D constituting the first surface. A The average major axis length L of the ellipse A The ellipse density D of the second surface is 20 to 80 μm. B The average major axis length L of the ellipse B 30~100μm.

[0242] The average major axis length L A The thickness is more preferably 30 to 70 μm, and still more preferably 40 to 68 μm.

[0243] The average major axis length L B The thickness is more preferably 35 to 90 μm, and still more preferably 40 to 80 μm.

[0244] The average major axis length L A is the ellipse density D A The average value of the major axis of the "ellipse" observed in the measurement.

[0245] The average major axis length L B is the ellipse density D B The average value of the major axis of the "ellipse" observed in the measurement.

[0246] The average major axis length L A and the aforementioned average major axis length L B The specific measurement method is based on the method described in the examples.

[0247] The density D of the ellipse constituting the first surface A The average major axis length L of the ellipse A When the value is 20 to 80 μm, it becomes easy to make the ellipticity density D of the first surface A In addition, the ellipse density D constituting the second surface is B The average major axis length L of the ellipse B When the thickness is 30 to 100 μm, it becomes easy to make the ellipticity D of the second surface B is within the aforementioned numerical range.

[0248] The polypropylene film preferably has an elliptical density D constituting the first surface. A The ellipse perfection P of the ellipse A The ellipse density D constituting the second surface is 30 to 70%. B The ellipse perfection P of the ellipse B It is 15 to 50%.

[0249] The above ellipse completeness P A It is more preferably 35 to 65%, and still more preferably 40 to 60%.

[0250] The above ellipse completeness P B It is more preferably 20 to 45%, and still more preferably 25 to 40%.

[0251] The above-mentioned ellipse completeness is a value obtained as follows.

[0252] First, as an optical interference type non-contact surface shape measuring machine, "VertScan2.0 (model R5500GML)" manufactured by Ryoka Systems Inc. was used. In WAVE mode, a 530 white filter and a 1×BODY lens barrel were applied, and a ×10 objective lens was used to obtain surface shape data of 470.92 μm × 353.16 μm in each field of view. This operation was performed at 10 locations at intervals of 1 cm from the center in the flow direction and width direction of the target sample (polypropylene film) along the flow direction.

[0253] Next, the obtained data was subjected to noise removal processing using a median filter (3×3), and then subjected to Gaussian filter processing with a cutoff value of 30 μm to remove the curvature component.

[0254] From the projection images of the surface shape data of the 10 locations obtained as described above (refer to Figure 2 ) are used to extract three arc crater projection images consisting of pairs of circular arcs.

[0255] Figure 2This is a diagram showing an example of a projection image obtained by projecting the part of fine concavities and convexities with a height of 0.02 μm or more onto the surface of a film using an optical interference type non-contact surface shape measuring device. Figure 2 The “projected image” is an image shown for easy visual understanding, and is not a projected image of a polypropylene film or the like in the examples described later.

[0256] When extracting crater projection images, three crater projection images are extracted in which no overlap of arcs based on different β-type spherulites is confirmed. The three extraction methods extract ellipses that become quartiles (the first quartile, the second quartile (i.e., the median), and the third quartile) in the area of ​​the ellipse based on visual observation. For example, when N crater projection images are confirmed, the crater projection image with the largest area of ​​[(3+N) / 4]th quartile, the crater projection image with the largest area of ​​[(1+N) / 2]th quartile, and the crater projection image with the largest area of ​​[(1+3N) / 4]th quartile are extracted. When the first to third quartiles obtained by substituting N have decimal points, the decimal points are rounded off so that the first to third quartiles become integers. Specifically, for example, when 9 crater projection images are confirmed, crater projection images with areas of No. 3, No. 5, and No. 7 are extracted. Also, for example, when 12 crater projection images are confirmed, crater projection images with areas of No. 4, No. 7, and No. 9 are extracted.

[0257] Next, for the three extracted crater projection images, the total length Lt of the paired arcs and the total circumference Lc of the imaginary circular ring containing the paired arcs are measured respectively to obtain the ratio (Lt / Lc). Then, the total 30 values ​​of the aforementioned ratio obtained are averaged to obtain the average value α of the ratio (Lt / Lc).

[0258] The virtual ring was determined and Lt and Lc were measured using the plug-in function "Edge Curve Length" of the analysis software "VS-Viewer" of the optical interference non-contact surface shape measuring instrument VertScan 2.0. The specific steps are as follows.

[0259] Figure 3 (a)~ Figure 3 (c) is a schematic top view for explaining the method of determining the imaginary circular ring.

[0260] (1) First, Figure 3 As shown in (a), let the two points on the arc 30a and the arc 30b that are farthest from each other be P 1 , P 2 , make sure P is connected 1 With P 2The straight line (hereinafter referred to as the straight line (P 1 -P 2 )).

[0261] (2) Then, Figure 3 As shown in (b), from the straight line (P 1 -P 2 ) on one side ( Figure 3 In the middle, the ratio of the straight line (P 1 -P 2 ) is also on the upper side. From the shapes (position data) of the arcs 30a and 30b of the portion ) of FIG. 3 , a straight line (P 1 -P 2 ) becomes the major axis of the ellipse (E 0 ). Then, the ellipse (E 0 ) of the curve (ellipse (E 0 ) is a part of the circumference of the circle, and the part between the arc 30a and the arc 30b on the above side is supplemented as the supplementary line 40a. It should be noted that, Figure 3 In the example, the ellipse (E 0 ) in the figure, except for the portion corresponding to the supplementary line 40a, the illustration is omitted.

[0262] (3) Then, Figure 3 As shown in (c), from the straight line (P 1 -P 2 ) on the other side ( Figure 3 In the middle, the ratio of the straight line (P 1 -P 2 ) is still on the lower side. From the shapes (position data) of the arcs 30a and 30b of the portion ) of FIG. 3 , a straight line (P 1 -P 2 ) becomes the major axis of the ellipse (E 1 ). Then, the ellipse (E 1 ) of the curve (ellipse (E 1 ) is a part of the circumference of the arc 30a, and the part between the arc 30a and the arc 30b on the other side is supplemented as a supplementary line 40b. It should be noted that Figure 3 In the example, the ellipse (E 1 ) in the figure, except for the portion corresponding to the supplementary line 40b, the illustration is omitted.

[0263] (4) The following is obtained by connecting the supplementary lines 40a, 40b determined in this way with the arcs 30a, 30b: Figure 3 The ring shown in (c) is a hypothetical ring.

[0264] (5) Then, a height profile of the fine asperities 20 is drawn, which indicates the height of the fine asperities 20 at each position relative to the circumference of the imaginary ring (the distance when a certain point of the circumference is used as a reference). From the height profile, Lt and Lc in the crater projection image G corresponding to the portion with a height of 0.02 μm or more are read.

[0265] It should be noted that when the least square method was implemented, 30 (n=30) pieces of position data were used.

[0266] If the above ellipse is perfect, A 40-60%, the above-mentioned ellipse completeness P B If the content is 25 to 35%, the dielectric breakdown strength can be maintained and the sticking after the metal layer is formed can be suppressed. This is preferable because it is related to the suppression of wrinkles when unwinding in the subsequent slitting process.

[0267] The DC dielectric breakdown strength ES of the polypropylene film at 100°C is preferably 510V. DC / μm or more, more preferably 525V DC / μm or more, more preferably 540V DC The DC dielectric breakdown strength ES of the polypropylene film at 100°C is preferably higher, but is, for example, 600 V DC / μm or less, 570V DC / μm or less, 550V DC / μm or less.

[0268] The DC dielectric breakdown strength ES of the polypropylene film at 120°C is preferably 485V DC / μm or more, more preferably 490V DC The DC dielectric breakdown strength ES of the polypropylene film at 125°C is preferably higher, but is, for example, 600 V DC / μm or less, 550V DC / μm or less.

[0269] The ash content of the polypropylene film is preferably 6×10 ppm or less (60 ppm or less), more preferably 5×10 ppm or less (50 ppm or less), further preferably 4×10 ppm or less (40 ppm or less), and particularly preferably 3×10 ppm or less (30 ppm or less) relative to the polypropylene film. The ash content is preferably 0×10 ppm or more, more preferably 1 ppm or more, further preferably 5 ppm or more, and particularly preferably 1×10 ppm or more (10 ppm or more). If the ash content is within the numerical range, the generation of low-molecular components with polarity is suppressed, and the electrical characteristics as a capacitor are further improved. The ash content refers to the value obtained by the method described in the examples.

[0270] The thickness of the polypropylene film is preferably 9.5 μm or less, more preferably 6.0 μm or less, further preferably 3.0 μm or less, further preferably 2.9 μm or less, particularly preferably 2.8 μm or less, and particularly preferably 2.5 μm or less. In addition, the thickness of the polypropylene film is preferably 0.8 μm or more, more preferably 1.0 μm or more, further preferably 1.4 μm or more, further preferably 1.5 μm or more, and particularly preferably 1.8 μm or more. In particular, when it is within the range of 1.4 to 6.0 μm, 1.5 to 3.0 μm, 1.5 to 2.9 μm, etc., although the polypropylene film is very thin, it is excellent in processability in the slitting process, adhesion suppression during the vapor deposition process, and component winding processability, so it is preferred.

[0271] When the thickness is 9.5 μm or less, the electrostatic capacitance can be increased, and thus the film can be suitably used as a capacitor. In addition, from the viewpoint of production, the thickness can be 0.8 μm or more.

[0272] The thickness of the polypropylene film is a value measured at 100±10 kPa using a paper thickness measuring instrument MEI-11 manufactured by CITIZEN SEIMITSU CO., LTD., and other values ​​measured in accordance with JIS-C2330.

[0273] The polypropylene film may be a biaxially stretched film, a uniaxially stretched film, or an unstretched film. A ), the Spk value of the first surface (Spk A ), the Svk value of the second surface (Svk B ) and the Spk value of the second side mentioned above (Spk B ) is within the aforementioned numerical range, a biaxially stretched film is preferred.

[0274] The aforementioned polypropylene film and the metal layer integrated polypropylene film are respectively wound into a roll shape, preferably in the form of a film roll. The aforementioned film roll may have a roll core (core) or may not have a roll core (core). The aforementioned film roll preferably has a roll core (core). The material of the roll core of the aforementioned film roll is not particularly limited. As the aforementioned material, paper (paper tube), resin, fiber reinforced plastic (FRP), metal, etc. can be cited. For the aforementioned resin, as an example, polyvinyl chloride, polyethylene, polypropylene, phenolic resin, epoxy resin, acrylonitrile-butadiene-styrene copolymer, etc. can be cited. As the plastic constituting the aforementioned fiber reinforced plastic, polyester resin, epoxy resin, vinyl ester resin, phenolic resin, thermoplastic resin, etc. can be cited. As the fiber constituting the aforementioned fiber reinforced plastic, glass fiber, aramid fiber (Kevlar (registered trademark) fiber), carbon fiber, polyparaphenylene benzoxazole fiber (Zylon (registered trademark) fiber), polyethylene fiber, boron fiber, etc. can be cited. As the aforementioned metal, iron, aluminum, stainless steel, etc. can be cited. The core of the film roll may include a core formed by impregnating a paper tube with the resin. In the above case, the material of the core is classified as the resin.

[0275] As mentioned above, the polypropylene film contains a polypropylene resin as a main component. In this specification, containing a polypropylene resin as a main component means that the polypropylene film contains 50% by mass or more of the polypropylene resin relative to the entire polypropylene film (when the entire polypropylene film is set to 100% by mass). The content of the polypropylene resin relative to the entire polypropylene film is preferably 75% by mass or more, more preferably 90% by mass or more. The upper limit of the content of the polypropylene resin relative to the entire polypropylene film is, for example, 100% by mass, 98% by mass, etc.

[0276] The polypropylene resin is not particularly limited, and one type may be used alone or two or more types may be used in combination. Among the polypropylene resins, a polypropylene resin that forms β-type spherulites when formed into a cast sheet is preferred.

[0277] As the aforementioned polypropylene resin, a linear polypropylene resin can be cited. The linear polypropylene resin can be used alone or in combination of two or more. Among them, it is preferred to use the following linear polypropylene resin A and / or the following linear polypropylene resin B. It is particularly preferred to use the following linear polypropylene resin A and the following linear polypropylene resin B in combination. The following linear polypropylene resin A and the following linear polypropylene resin B are preferably homopolypropylene resins. As a combination of the following linear polypropylene resin A and the following linear polypropylene resin B, the following resin A-1 and the following resin B-1, the following resin A-2 and the following resin B-2, the following resin A-3 and the following resin B-3, and the following resin A-4 and the following resin B-4 can be cited as suitable examples. However, in the first present invention, the aforementioned polypropylene resin is not limited to the following resins.

[0278] <Linear polypropylene resin A>

[0279] (Linear Polypropylene Resin A-1)

[0280] In the molecular weight differential distribution curve, when the differential distribution value when Log(M)=6.0 is set as 100% (base), a linear polypropylene resin is obtained by subtracting the differential distribution value when Log(M)=6.0 from the differential distribution value when the logarithmic molecular weight Log(M)=4.5, and the difference is 8.0% or more.

[0281] (Linear Polypropylene Resin A-2)

[0282] A linear polypropylene resin having a heptane-insoluble matter (HI) of 98.5% or less.

[0283] (Linear Polypropylene Resin A-3)

[0284] A linear polypropylene resin having a melt flow rate (MFR) at 230°C of 4.0 to 10.0 g / 10 minutes.

[0285] (Linear Polypropylene Resin A-4)

[0286] A linear polypropylene resin having a weight average molecular weight Mw of 340,000 or less.

[0287] <Linear polypropylene resin B>

[0288] (Linear Polypropylene Resin B-1)

[0289] A linear polypropylene resin wherein the difference obtained by subtracting the differential distribution value when Log(M)=6.0 from the differential distribution value when Log(M)=4.5 is less than 8.0% when the differential distribution value when Log(M)=6.0 is taken as 100% (base) in the molecular weight differential distribution curve.

[0290] (Linear Polypropylene Resin B-2)

[0291] A linear polypropylene resin having a heptane insoluble matter (HI) exceeding 98.5%.

[0292] (Linear Polypropylene Resin B-3)

[0293] A linear polypropylene resin having a melt flow rate (MFR) at 230° C. of less than 4.0 g / 10 min (particularly a linear polypropylene resin of 0.1 to 3.9 g / 10 min).

[0294] (Linear Polypropylene Resin B-4)

[0295] A linear polypropylene resin having a weight average molecular weight Mw exceeding 340,000.

[0296] The weight average molecular weight Mw of the linear polypropylene resin A is preferably 250,000 or more. In addition, the weight average molecular weight Mw of the linear polypropylene resin A is preferably 450,000 or less, more preferably 400,000 or less, further preferably 350,000 or less, and particularly preferably 340,000 or less. If the weight average molecular weight Mw of the linear polypropylene resin A 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 sheet and the stretched film, and it becomes easy to produce a thin stretched film. In addition, it becomes difficult to produce unevenness in the thickness of the cast sheet and the stretched film, and appropriate stretchability can be obtained, so it is preferred.

[0297] The molecular weight distribution [(weight average molecular weight Mw) / (number average molecular weight Mn)] of the linear polypropylene resin A is preferably 5.5 to 12.0, more preferably 7.0 to 12.0, further preferably 7.5 to 11.0, particularly preferably 8.0 to 11.0, and even more preferably 9.0 to 11.0.

[0298] The molecular weight distribution [(z-average molecular weight Mz) / (number-average molecular weight Mn)] of the linear polypropylene resin A is preferably 15.0 to 70.0, more preferably 20.0 to 60.0, and further preferably 25.0 to 50.0.

[0299] When the molecular weight distribution of the linear polypropylene resin A is within the above preferred range, unevenness in thickness of a cast sheet or a stretched film is less likely to occur, and appropriate stretchability can be obtained, which is preferred.

[0300] In this specification, the weight average molecular weight (Mw), number average molecular weight (Mn), Z average molecular weight and molecular weight distribution (Mw / Mn and Mz / Mn) of the linear polypropylene resin A and the linear polypropylene resin B are values ​​measured by a gel permeation chromatography (GPC) apparatus. In this specification, the values ​​are measured using HLC-8121GPC-HT (trade name), a high temperature GPC measuring machine 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 were connected and used. The column temperature was set to 140°C, and trichlorobenzene as an eluent was allowed to flow at a flow rate of 1.0 ml / 10 minutes to obtain the measured values ​​of Mw and Mn. A standard curve for the molecular weight M of standard polystyrene manufactured by Tosoh Corporation was prepared, and the measured values ​​were converted to the molecular weight of polypropylene using the Q-factor to obtain Mw, Mn and Mz. Furthermore, the logarithm to the base 10 of the molecular weight M is referred to as the logarithmic molecular weight ("Log(M)").

[0301] 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 long-chain branched polypropylene C are values ​​measured by a gel permeation chromatography (GPC) apparatus. More specifically, the measurement is performed by high temperature GPC-MALS measurement, that is, a high temperature GPC apparatus (HLC-8121GPC / HT; manufactured by Tosoh) equipped with a light scattering detector (DAWN EOS; manufactured by Wyatt Technology). As columns, TSK gelguard column HHR (30) (7.8 mm ID × 7.5 cm) and three TSK gel GMH-HR-H (20) HT (7.8 mm ID × 30 cm) manufactured by Tosoh Corporation were connected and used. The column temperature was set to 140° C., and trichlorobenzene as an eluent was allowed to flow at a flow rate of 1.0 ml / 10 minutes to obtain the measured values ​​of Mw and Mn.

[0302] For the above linear polypropylene resin A, the differential distribution value difference D M Preferably 8.0% or more, the differential distribution value difference D of the linear polypropylene resin A M It is more preferably 8.0% to 18.0% both inclusive, further preferably 9.0% to 17.0% both inclusive, and particularly preferably 10.0% to 16.0% both inclusive.

[0303] The above differential distribution value difference D of the above linear polypropylene resin A M The content of 8.0% or more and 18.0% or less can be understood as follows: when comparing a component having a logarithmic molecular weight Log(M)=4.5, which is a representative distribution value of a component having a molecular weight of 10,000 to 100,000 on the low molecular weight side (hereinafter also referred to as a "low molecular weight component"), with a component having a representative distribution value Log(M)=6.0, which is a representative distribution value of a component having a molecular weight of about 1,000,000 on the high molecular weight side (hereinafter also referred to as a "high molecular weight component"), the low molecular weight component accounts for more than 8.0% and less than 18.0%.

[0304] That is, for example, when the molecular weight distribution Mw / Mn is 7.0 to 12.0, even if the molecular weight distribution Mw / Mn is 7.0 to 12.0, it simply indicates the width of the molecular weight distribution, and does not even make clear the quantitative relationship between the high molecular weight component and the low molecular weight component. Therefore, the linear polypropylene resin A contains a larger proportion of 8.0% or more and 18.0% or less of the component with a molecular weight of 1,000,000 to 100,000 than the component with a molecular weight of 1,000,000.

[0305] The above differential distribution value difference D of the above linear polypropylene resin A MWhen the content is 8.0% to 18.0%, the low molecular weight component is contained in a larger proportion of 8.0% to 18.0% compared to the high molecular weight component. Therefore, the surface of the thin film in the first embodiment can be easily obtained, which is preferable.

[0306] The aforementioned differential distribution value is a value obtained using GPC as follows. A curve representing intensity relative to time (also commonly referred to as a "dissolution curve") is obtained using a differential refractometer (RI) detector of GPC. Using a standard curve obtained using standard polystyrene, the time axis is converted into a logarithmic molecular weight (Log(M)), thereby converting the dissolution curve into a curve representing intensity relative to Log(M). The RI detection intensity is proportional to the component concentration, so when the entire area of ​​the curve representing the intensity is set to 100%, an integral distribution curve relative to the logarithmic molecular weight Log(M) can be obtained. The differential distribution curve is obtained by differentiating the integral distribution curve with Log(M). Therefore, "differential distribution" refers to the differential distribution of concentration fraction relative to molecular weight. From this curve, the differential distribution value at a specific Log(M) is read.

[0307] The meso pentad fraction ([mmmm]) of the linear polypropylene resin A is preferably 99.8% or less, more preferably 99.5% or less, and further preferably 99.0% or less. In addition, the meso pentad fraction is preferably 94.0% or more, more preferably 94.5% or more, and further preferably 95.0% or more. If the meso pentad fraction is within the above numerical range, the crystallinity of the resin is moderately improved due to the moderately high stereoregularity, and the withstand voltage at high temperature is improved. On the other hand, the curing (crystallization) speed during the casting sheet molding becomes moderate, and the cast sheet has moderate stretchability.

[0308] The meso pentad fraction ([mmmm]) is an index of stereoregularity that can be obtained by high temperature nuclear magnetic resonance (NMR) measurement. In this specification, the meso pentad 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 observed nucleus is 13 C (125MHz), the measurement temperature is 135°C, and the solvent for dissolving the polypropylene resin is o-dichlorobenzene (ODCB: a mixed solvent of ODCB and deuterated hydrogenated ODCB (mixing ratio = 4 / 1). The measurement method based on high temperature NMR can be carried out with reference to the method described in "Japan Analytical Chemistry and Polymer Analysis Research Conference, New Edition Polymer Analysis Handbook, Kinokuniya Bookstore, 1995, page 610". A more detailed measurement method for the meso pentad fraction ([mmmm]) is based on the method described in the Examples.

[0309] The heptane-insoluble matter (HI) of the aforementioned linear polypropylene resin A is preferably 96.0% or more, more preferably 97.0% or more. In addition, the heptane-insoluble matter (HI) of the aforementioned linear polypropylene resin A is preferably 99.5% or less, more preferably 98.5% or less, and further preferably 98.0% or less. Here, the more heptane-insoluble matter there is, the higher the stereoregularity of the resin. If the aforementioned heptane-insoluble matter (HI) is 96.0% or more and 99.5% or less, the crystallinity of the resin is moderately improved due to the moderately high stereoregularity, and the voltage resistance at high temperature is improved. On the other hand, the speed of solidification (crystallization) during casting sheet molding becomes moderate, and moderate stretchability is obtained. The method for measuring the heptane-insoluble matter (HI) is based on the method described in the examples.

[0310] The ash content of the linear polypropylene resin A is preferably 6×10 ppm or less (60 ppm or less), more preferably 5×10 ppm or less (50 ppm or less), further preferably 4×10 ppm or less (40 ppm or less), and particularly preferably 3×10 ppm or less (30 ppm or less). In addition, the ash content of the linear polypropylene resin A is preferably 0×10 ppm or more, more preferably 1 ppm or more, further preferably 5 ppm or more, and particularly preferably 1×10 ppm or more (10 ppm or more). When the ash content of the linear polypropylene resin A is within the above preferred range, the generation of low molecular weight components having polarity is suppressed, and the electrical characteristics as a capacitor are further improved. The ash content is a value obtained by the method described in the Examples.

[0311] The melt flow rate (MFR) of the linear polypropylene resin A at 230°C is preferably 1.0 to 15.0 g / 10 minutes, more preferably 2.0 to 10.0 g / 10 minutes, further preferably 4.0 to 10.0 g / 10 minutes, and particularly preferably 4.3 to 6.0 g / 10 minutes. When the MFR at 230°C of the polypropylene A is within the above range, the flow characteristics in the molten state are excellent, so unstable flow such as melt fracture is not likely to occur, and breakage during stretching is also suppressed. Therefore, there is an advantage that the uniformity of the film thickness is good, and therefore, the formation of thin-walled parts that are prone to dielectric breakdown is suppressed. The method for measuring the melt flow rate is based on the method described in the examples.

[0312] The content of the linear polypropylene resin A is preferably 55% by mass or more, more preferably 60% by mass or more, based on 100% by mass of the entire polypropylene resin in the polypropylene film. The content of the linear polypropylene resin A is preferably 99.9% by mass or less, more preferably 90% by mass or less, further preferably 85% by mass or less, and particularly preferably 80% by mass or less, based on 100% by mass of the entire polypropylene resin in the polypropylene film.

[0313] The weight average molecular weight Mw of the linear polypropylene resin B is preferably 300,000 or more, more preferably 330,000 or more, further preferably more than 340,000, further preferably 350,000 or more, and particularly preferably more than 350,000. The weight average molecular weight Mw of the linear polypropylene resin B is preferably 400,000 or less, more preferably 380,000 or less.

[0314] The molecular weight distribution [(weight average molecular weight Mw) / (number average molecular weight Mn)] of the linear polypropylene resin B is preferably 7.0 to 9.0, more preferably 7.5 to 8.9, and further preferably 7.5 to 8.5.

[0315] The molecular weight distribution [(z-average molecular weight Mz) / (number-average molecular weight Mn)] of the linear polypropylene resin B is preferably 20.0 to 70.0, more preferably 25.0 to 60.0, and even more preferably 25.0 to 50.0.

[0316] When the molecular weight distribution of the linear polypropylene resin B is within the above preferred range, unevenness in thickness of a cast sheet or a stretched film is less likely to occur, and appropriate stretchability can be obtained, which is preferred.

[0317] The differential distribution value difference D of the above linear polypropylene resin B M It is preferably less than 8.0%, more preferably -20.0% to less than 8.0%, further preferably -10.0% to 7.9%, particularly preferably -5.0% to 7.5%.

[0318] The meso pentad fraction ([mmmm]) of the linear polypropylene resin B is preferably less than 99.8%, more preferably less than 99.5%, and further preferably less than 99.0%. In addition, the meso pentad fraction is preferably 94.0% or more, more preferably 94.5% or more, and further preferably 95.0% or more. If the meso pentad fraction is within the above numerical range, the crystallinity of the resin is moderately improved due to the moderately high stereoregularity, and the voltage resistance at high temperature is improved. On the other hand, the curing (crystallization) speed during the casting sheet molding becomes moderate, and the cast sheet has moderate stretchability.

[0319] The heptane-insoluble matter (HI) of the linear polypropylene resin B is preferably 97.5% or more, more preferably 98% or more, further preferably more than 98.5%, particularly preferably 98.6% or more. The heptane-insoluble matter (HI) of the linear polypropylene resin B is preferably 99.5% or less, more preferably 99% or less.

[0320] The ash content of the linear polypropylene resin B is preferably 6×10 ppm or less (60 ppm or less), more preferably 5×10 ppm or less (50 ppm or less), further preferably 4×10 ppm or less (40 ppm or less), and particularly preferably 3×10 ppm or less (30 ppm or less). In addition, the ash content of the linear polypropylene resin B is preferably 0×10 ppm or more, more preferably 1 ppm or more, further preferably 5 ppm or more, and particularly preferably 1×10 ppm or more (10 ppm or more). When the ash content of the linear polypropylene resin B is within the above preferred range, the generation of low molecular weight components having polarity is suppressed, and the electrical characteristics as a capacitor are further improved. The ash content is a value obtained by the method described in the Examples.

[0321] The melt flow rate (MFR) of the linear polypropylene resin B at 230°C is preferably 0.1 g / 10 min or more. The melt flow rate (MFR) of the linear polypropylene resin B at 230°C is preferably 6.0 g / 10 min or less, more preferably 5.0 g / 10 min or less, further preferably less than 4.0 g / 10 min, particularly preferably 3.9 g / 10 min or less.

[0322] When the linear polypropylene resin B is used as the polypropylene resin, the content of the linear polypropylene resin B is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, based on 100% by mass of the entire polypropylene resin in the polypropylene film. Similarly, the content of the linear polypropylene resin B is preferably 45% by mass or less, and more preferably 40% by mass or less, based on 100% by mass of the entire polypropylene resin in the polypropylene film.

[0323] When the linear polypropylene resin A and the linear polypropylene resin B are used in combination as the polypropylene resin, when the entire polypropylene resin is set to 100% by weight, it is preferred that the linear polypropylene resin A be contained in an amount of 55 to 90% by weight and the linear polypropylene resin B be contained in an amount of 45 to 10% by weight, more preferably 60 to 85% by weight and the linear polypropylene resin A be contained in an amount of 40 to 15% by weight, and particularly preferably 60 to 80% by weight and the linear polypropylene resin A be contained in an amount of 40 to 20% by weight.

[0324] When the polypropylene resin includes the linear polypropylene resin A and the linear polypropylene resin B, the polypropylene film is in a finely mixed state (phase-separated state) of the linear polypropylene resin A and the linear polypropylene resin B, and thus the withstand voltage at high temperatures is improved.

[0325] The linear polypropylene resin can be generally produced by a known polymerization method. There is no particular limitation as long as the linear polypropylene resin used in the polypropylene film of the first embodiment can be produced. Examples of such polymerization methods include gas phase polymerization, bulk polymerization, and slurry polymerization.

[0326] The polymerization may be a single-stage polymerization using one polymerization reactor or a multi-stage polymerization using at least two polymerization reactors. Furthermore, hydrogen or a comonomer may be added to the reactor as a molecular weight modifier.

[0327] The catalyst used in the polymerization may be a commonly known Ziegler-Natta catalyst, and is not particularly limited as long as the linear polypropylene resin can be obtained. The catalyst may include a co-catalyst component and a donor. By adjusting the catalyst and polymerization conditions, the molecular weight, molecular weight distribution, stereoregularity, etc. can be controlled.

[0328] The molecular weight, molecular weight distribution, and differential distribution value difference D of the above linear polypropylene resin M The above-mentioned conditions can be adjusted by appropriately selecting (i) the polymerization method and the temperature and pressure during the polymerization, (ii) the form of the reactor during the polymerization, (iii) the presence, type and amount of additives, (iv) the type and amount of catalyst, etc.

[0329] Specifically, the molecular weight, molecular weight distribution, and differential distribution value difference D of the linear polypropylene resin are M The adjustment of the above can be performed, for example, by a multi-stage polymerization reaction. As a multi-stage polymerization reaction, for example, the following method can be exemplified.

[0330] First, in the first polymerization step, propylene and a catalyst are supplied to the first polymerization reactor. These components are mixed together with hydrogen as a molecular weight regulator in an amount required to achieve the desired molecular weight of the polymer. The reaction temperature is about 70 to 100°C in the case of slurry polymerization, for example, and the residence time is about 20 minutes to 100 minutes. Multiple reactors can be used in series, for example. In the above case, the polymerization product of the first step is continuously sent to the following reactor together with additional propylene, catalyst, and molecular weight regulator, and then a second polymerization is carried out to adjust the molecular weight to a lower molecular weight or a higher molecular weight than that of the first polymerization step. By adjusting the yield (production volume) of the first and second reactors, the composition (constitution) of the high molecular weight component and the low molecular weight component can be adjusted.

[0331] In addition, the molecular weight, molecular weight distribution, and differential distribution value difference D of the above-mentioned linear polypropylene resin are MThe adjustment of the above mentioned conditions can also be performed by peroxidation decomposition. For example, a method based on peroxidation treatment using a decomposition agent such as hydrogen peroxide or an organic peroxide can be exemplified.

[0332] If peroxide is added to a disintegrating polymer such as polypropylene, a hydrogen abstraction reaction from the polymer will occur, and some of the generated polymer free radicals will recombine, which will also cause a cross-linking reaction, but most of the free radicals will cause secondary decomposition (β cleavage) and be separated into two polymers with smaller molecular weights. That is, the higher the molecular weight component, the higher the probability of decomposition. As a result, the low molecular weight component increases, and the composition of the molecular weight distribution can be adjusted.

[0333] When adjusting the content of low molecular weight components by blending (resin mixing), at least two or more resins with different molecular weights can be dry-blended or melt-blended. Generally, since the amount of low molecular weight components can be easily adjusted, it is preferred to use a mixed system of two polypropylenes having an average molecular weight higher or lower than that of an additional resin of the main resin by about 1 to 40% by mass.

[0334] In addition, in the case of the mixing adjustment, the melt flow rate (MFR) can be used as a target of the average molecular weight. In the above case, from the viewpoint of convenience during adjustment, the difference in MFR between the main resin and the added resin can be set to about 1 to 30 g / 10 minutes in advance.

[0335] As the linear polypropylene resin, a commercially available product may be used.

[0336] The polypropylene resin preferably includes a long-chain branched polypropylene resin. Among the long-chain branched polypropylene resins, a long-chain branched polypropylene resin C (hereinafter also referred to as "long-chain branched polypropylene resin C") obtained by polymerizing propylene using a metallocene catalyst is preferred. Specifically, if the long-chain branched polypropylene resin C is included in the polypropylene resin, a large amount of β crystals are formed in the cast sheet. Moreover, by stretching the cast sheet containing β crystals, the β crystals are transformed into α crystals. Therefore, the polypropylene film obtained by stretching due to the difference in density between the β crystals and the α crystals is formed with (roughly) arc-shaped concavities and convexities, which can suitably roughen the surface, which is preferred.

[0337] Among them, it is more preferred that the polypropylene resin includes the linear polypropylene resin A and the long-chain branched polypropylene resin C.

[0338] Furthermore, it is more preferred that the polypropylene resin includes the linear polypropylene resin A and the linear polypropylene resin B, and includes the long-chain branched polypropylene resin C. The differential distribution value difference D between the linear polypropylene resin A and the linear polypropylene resin B is M, heptane insoluble matter (HI) and / or melt flow rate (MFR) are different, and the film is in a finely mixed state (phase separation state). Therefore, the configuration of the resin components constituting the film by stretching such an unstretched polypropylene film becomes complicated. M In addition to the linear polypropylene resin A and the linear polypropylene resin B having different contents of heptane-insoluble matter (HI) and / or melt flow rate (MFR), a long-chain branched polypropylene resin C is also included, thereby improving the voltage resistance of the stretched film caused by the complication of the configuration of the resin components constituting the film, and forming micronized (roughly) arc-shaped bumps and depressions to achieve more suitable roughening.

[0339] It should be noted that, if a long-chain branched polypropylene resin obtained by crosslinking modification of peroxide is used instead of a long-chain branched polypropylene resin C obtained by polymerization using a metallocene catalyst, the formation of α crystals in the casting sheet is promoted based on the α crystal nucleation effect of the long-chain branched polypropylene resin obtained by crosslinking modification of peroxide, and the formation of β crystals becomes greatly suppressed. Even if the casting sheet containing α crystals is stretched, the transformation of crystallites is not caused, and therefore, it is difficult to form concavoconvex. Therefore, in order to roughen the polypropylene film, the long-chain branched polypropylene resin C obtained by polymerization using a metallocene catalyst is suitable.

[0340] Metallocene catalysts are usually metallocene compounds that form polymerization catalysts for generating olefin macromonomers. The long-chain branched polypropylene resin C obtained by polymerizing propylene using a metallocene catalyst has a moderate branch length and branch spacing of the polypropylene, which can obtain excellent compatibility with linear polypropylene, so it is preferred. In addition, a uniform composition and a uniform surface shape can be obtained, so it is preferred. In the production of long-chain branched polypropylene resin C, the conditions other than the type and amount of the catalyst used, such as (i) the polymerization method and the temperature and pressure conditions during polymerization, (ii) the shape of the reactor during polymerization, and (iii) the presence, type and amount of additives, etc., are considered in terms of the molecular weight, molecular weight distribution, and differential distribution value difference D of the produced long-chain branched polypropylene resin C. M The conditions are the same as those described in the section of the method for producing the linear polypropylene resin.

[0341] The weight average molecular weight Mw of the long-chain branched polypropylene resin C is preferably 150,000 to 600,000, more preferably 200,000 to 500,000, further preferably 250,000 to 450,000, and particularly preferably 350,000 to 420,000. If the weight average molecular weight Mw of the long-chain branched polypropylene resin C is 150,000 to 600,000, the resin fluidity becomes appropriate. As a result, it is easy to control the thickness of the cast sheet and the stretched film, and it becomes easy to produce a thin stretched film. In addition, it becomes difficult to produce uneven thickness in the cast sheet and the stretched film, and appropriate stretchability can be obtained, so it is preferred.

[0342] The molecular weight distribution [(weight average molecular weight Mw) / (number average molecular weight Mn)] of the long-chain branched polypropylene resin C is preferably 1.5 to 4.5, more preferably 1.8 to 4.2, further preferably 2.0 to 4.0, particularly preferably 2.1 to 3.9, particularly preferably 2.2 to 3.0.

[0343] The [(z average molecular weight Mz) / (number average molecular weight Mn)] of the long-chain branched polypropylene resin C is preferably 4.0 to 9.0, more preferably 4.2 to 8.8, further preferably 4.5 to 8.5, particularly preferably 5.0 to 8.2.

[0344] The molecular weight, molecular weight distribution and differential distribution value difference D of the long-chain branched polypropylene resin C are M As mentioned above, it can be controlled by adjusting the catalyst and polymerization conditions.

[0345] The heptane-insoluble matter (HI) of the long-chain branched polypropylene resin C is preferably 98.0% or more, more preferably 98.2% or more, and further preferably 98.5% or more. In addition, the heptane-insoluble matter (HI) of the long-chain branched polypropylene resin C is preferably 99.5% or less, and more preferably 99.0% or less. When the HI of the long-chain branched polypropylene resin C is within the above preferred range, β crystals are more suitably formed in the cast sheet, and as a result, the surface of the polypropylene film of the first embodiment can be suitably roughened.

[0346] The ash content of the long-chain branched polypropylene resin C is preferably 45×10 ppm or less (450 ppm or less), more preferably 40×10 ppm or less (400 ppm or less). In addition, the ash content of the long-chain branched polypropylene resin C is preferably 0×10 ppm or more, more preferably 1 ppm or more, still more preferably 5 ppm or more, further preferably 1×10 ppm or more (10 ppm or more), further still preferably 10×10 ppm or more (100 ppm or more), and particularly preferably 20×10 ppm or more (200 ppm or more). When the ash content of the long-chain branched polypropylene resin C is within the above preferred range, β crystals are more suitably formed in the cast sheet, and as a result, the surface of the polypropylene film of the first embodiment can be suitably roughened.

[0347] The melt flow rate (MFR) of the long-chain branched polypropylene resin C at 230°C is preferably 0.1 to 12 g / 10 minutes, more preferably 0.5 to 5 g / 10 minutes, further preferably 0.7 to 3.5 g / 10 minutes, and particularly preferably 1.0 to 2.2 g / 10 minutes. When the MFR at 230°C of the long-chain branched polypropylene resin C is within the above range, the flow characteristics in the molten state are excellent, so unstable flow such as melt fracture is less likely to occur, and breakage during stretching is also suppressed. Therefore, there is an advantage that the uniformity of the film thickness is good, and therefore the formation of thin-walled parts that are likely to cause dielectric breakdown is suppressed.

[0348] The content of the long-chain branched polypropylene resin C is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, further preferably 1% by mass or more, particularly preferably 2% by mass or more, and more particularly preferably 2.5% by mass or more, when the entire polypropylene resin in the polypropylene film is 100% by mass. In addition, the content of the long-chain branched polypropylene resin C is preferably 30% by mass or less, more preferably 20% by mass or less, further preferably 10% by mass or less, particularly preferably 7% by mass or less, and more particularly preferably 5% by mass or less, when the entire polypropylene resin in the polypropylene film is 100% by mass. The polypropylene film may contain one or more of the long-chain branched polypropylene resins C.

[0349] Typical commercial products of the long-chain branched polypropylene resin C include, for example, MFX3 and MFX6 manufactured by Japan Polypropylene Corporation and MFX8 manufactured by Japan Polypropylene Corporation.

[0350] The aforementioned polypropylene film may contain other resins (hereinafter also referred to as "other resins") other than the polypropylene resin. "Other resins" are generally resins other than the polypropylene resin that is the main component of the resin, and there is no particular restriction as long as the target polypropylene film can be obtained. As other resins, for example, other polyolefins other than polypropylene such as polyethylene, poly (1-butene), polyisobutylene, poly (1-pentene), poly (1-methylpentene), ethylene-propylene copolymers, propylene-butene copolymers, α-olefin copolymers such as ethylene-butene copolymers, vinyl monomers such as styrene-butadiene random copolymers-diene monomers random copolymers, styrene-butadiene-styrene block copolymers, etc. can be cited. The aforementioned polypropylene film can be included in an amount that does not adversely affect the target polypropylene film. The aforementioned polypropylene film preferably contains 10 parts by mass or less of other resins relative to 100 parts by mass of the polypropylene resin, and more preferably can contain 5 parts by mass or less. In addition, the aforementioned polypropylene film preferably contains 0.1 parts by mass or more of other resins relative to 100 parts by mass of the polypropylene resin, and more preferably can contain 1 part by mass or more.

[0351] The aforementioned polypropylene film may further contain at least one additive based on the resin component. "Additive" refers to the additives commonly used in polypropylene, and there is no particular limitation as long as the target polypropylene film can be obtained. The additives may include, for example, nucleating agents (α-crystal nucleating agents, β-crystal nucleating agents), antioxidants, chlorine absorbers, UV absorbers and other required stabilizers, lubricants, plasticizers, flame retardants, antistatic agents, inorganic fillers, organic fillers and the like. Examples of the aforementioned inorganic fillers include barium titanate, strontium titanate, aluminum oxide and the like. When the aforementioned additives are used, they may be included in an amount that does not adversely affect the target polypropylene film.

[0352] The "nucleating agent" is not particularly limited as long as it is generally used for polypropylene and can provide the intended polypropylene film.

[0353] Examples of the nucleating agent include an α-crystal nucleating agent that preferentially forms nuclei of α-crystals and a β-crystal nucleating agent that preferentially forms nuclei of β-crystals.

[0354] As organic nucleating agents in α-crystal nucleating agents, dispersed nucleating agents and dissolved nucleating agents can be cited. As dispersed nucleating agents, phosphate metal salt nucleating agents, carboxylic acid metal salt nucleating agents, rosin metal salt nucleating agents, etc. can be cited. As dissolved nucleating agents, sorbitol nucleating agents, nonanol nucleating agents, xylitol nucleating agents, amide nucleating agents, etc. can be cited.

[0355] Examples of the β-crystal nucleating agent include amide nucleating agents, divalent or polyvalent carboxylic acid metal salt nucleating agents, quinacridone nucleating agents, aromatic sulfonic acid nucleating agents, phthalocyanine nucleating agents, and tetraoxaspiro compound nucleating agents.

[0356] The nucleating agent can also be used by dry mixing or melt blending with the polypropylene raw material and pelletizing, or it can be used by being put into an extruder together with the polypropylene pellets. By using a nucleating agent, the surface roughness of the film can be adjusted to the desired roughness. For example, as a representative commercial product of a nucleating agent, NJ STAR NU-100 manufactured by New Japan Chemical Co., Ltd. can be cited as a β-crystal nucleating agent. When the aforementioned polypropylene film contains a β-crystal nucleating agent, its content is preferably 1 to 1000 mass ppm, more preferably 50 to 600 mass ppm relative to the mass of the resin component (by mass when the resin component is taken as a whole).

[0357] "Antioxidant" means, generally referred to as antioxidant, and there is no particular limitation as long as it is used for polypropylene and the target polypropylene film can be obtained. Antioxidants are generally used for two purposes. One purpose is to suppress thermal degradation and oxidative degradation in the extruder, and the other purpose is to help suppress degradation during long-term use as a capacitor film and improve capacitor performance. Antioxidants that suppress thermal degradation and oxidative degradation in the extruder are also called "primary agents", and antioxidants that help improve capacitor performance are also called "secondary agents".

[0358] Two antioxidants may be used for these two purposes, or one antioxidant may be used for these two purposes.

[0359] As a primary agent, for example, 2,6-di-tert-butyl-p-cresol (common name: BHT) can be cited. The primary agent can be added for the purpose of suppressing thermal degradation and oxidative degradation in the extruder when the polypropylene resin composition described in the method for producing the polypropylene film described later is usually prepared. The antioxidant added to the polypropylene resin composition for this purpose is basically consumed in the molding process in the extruder and basically does not remain in the film after film molding. Therefore, when the aforementioned polypropylene film contains a primary agent, its content relative to the mass of the resin component (by mass when the resin component is taken as a whole) is generally less than 100 mass ppm.

[0360] As the secondary agent, there can be mentioned hindered phenol antioxidants having a carbonyl group.

[0361] The "hindered phenol antioxidant having a carbonyl group" is generally referred to as a hindered phenol antioxidant having a carbonyl group, and is not particularly limited as long as the target polypropylene film can be obtained.

[0362] Examples of the hindered phenol antioxidant having a carbonyl group include triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate] (trade name: Irganox 245), 1,6-hexanediol-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (trade name: Irganox 259), pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (trade name: Irganox 1010), 2,2-thiodiethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (trade name: Irganox 1035), octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (trade name: Irganox 1076), N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxy-hydrocinnamic acid amide) (trade name: Irganox 1098), etc., and particularly preferred is pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] which has a high molecular weight, rich compatibility with polypropylene, low volatility and excellent heat resistance.

[0363] For the purpose of suppressing the deterioration that occurs with the time during long-term use, the polypropylene film may contain one or more hindered phenolic antioxidants (secondary agents) having a carbonyl group. When the polypropylene film contains one or more hindered phenolic antioxidants having a carbonyl group, the content thereof is preferably 4000 mass ppm or more and 6000 mass ppm or less, and more preferably 4500 mass ppm or more and 6000 mass ppm or less relative to the mass of the resin component (by mass when the resin component is taken as a whole). When the content of the hindered phenolic antioxidant having a carbonyl group in the film is 4000 mass ppm or more and 6000 mass ppm or less, it is preferred from the viewpoint of reflecting an appropriate effect.

[0364] A polypropylene film containing a hindered phenol antioxidant having a carbonyl group having good compatibility with polypropylene at a molecular level in an optimal specific range is preferred because its long-term durability is improved.

[0365] "Chlorine absorbent" is generally referred to as a chlorine absorbent, and there is no particular limitation as long as it is used for polypropylene and the target polypropylene film can be obtained. Examples of the chlorine absorbent include metal soaps such as calcium stearate. When such a chlorine absorbent is used, it can be contained in an amount that does not adversely affect the target polypropylene film.

[0366] The polypropylene film is preferably biaxially stretched. When the polypropylene film is a biaxially stretched polypropylene film, the biaxially stretched polypropylene film can be produced by a commonly known method for producing a biaxially stretched polypropylene film. For example, the film can be produced by mixing a linear polypropylene resin A, a linear polypropylene resin B, and a long-chain branched polypropylene resin C with other resins, additives, etc. as needed to obtain a polypropylene resin composition, preparing a casting sheet from the obtained polypropylene resin composition, and then biaxially stretching the casting sheet to produce the film.

[0367] <Preparation of polypropylene resin composition>

[0368] There are no particular restrictions on the method for preparing the aforementioned polypropylene resin composition, and the following methods can be cited: a method in which polymer powders or pellets of linear polypropylene resin A, linear polypropylene resin B and long-chain branched polypropylene resin C are dry-blended together with other resins, additives, etc. using a mixer or the like as needed; a method in which polymer powders or pellets of linear polypropylene resin A, linear polypropylene resin B and long-chain branched polypropylene resin C are supplied to a kneader together with other resins, additives, etc. as needed, and melt-kneaded to obtain a melt-blended resin composition; and the like.

[0369] The mixer and kneader are not particularly limited. The kneader may be a single screw type, a twin screw type, or a multi-screw type. In the case of a twin screw or multi-screw type, the kneader may be a kneader that rotates in the same direction or in different directions.

[0370] In the case of blending by melt kneading, the kneading temperature is not particularly limited as long as good kneading can be obtained, and is preferably in the range of 170 to 320° C., more preferably in the range of 200 to 300° C., and further preferably in the range of 230 to 270° C. In order to suppress the deterioration of the resin during kneading and mixing, an inert gas such as nitrogen can be purged in the kneading machine. The melt-kneaded resin is granulated into a suitable size using a generally known granulator, thereby obtaining pellets of the melt-blended resin composition.

[0371] When preparing the polypropylene resin composition, a primary agent as an antioxidant as described in the above-mentioned section of additives may be added for the purpose of suppressing thermal degradation and oxidative degradation in an extruder.

[0372] When the polypropylene resin composition contains a primary agent, its content is preferably 1000 to 5000 ppm by mass relative to the mass of the resin component (the mass of the resin component as a whole). The antioxidant for this purpose is basically consumed in the molding process in the extruder and hardly remains in the film after film molding.

[0373] The hindered phenol antioxidant having a carbonyl group described in the section of the above additives may be added to the polypropylene resin composition as a secondary agent.

[0374] When the polypropylene resin composition contains a hindered phenol antioxidant having a carbonyl group, the content thereof is preferably 100 to 10,000 ppm by mass, more preferably 5,500 to 7,000 ppm by mass, relative to the mass of the resin component (the mass of the resin component as a whole). The hindered phenol antioxidant having a carbonyl group is also greatly consumed in the extruder.

[0375] When the polypropylene resin composition does not contain a primary agent, more hindered phenol antioxidants having a carbonyl group can be used. This is because the consumption of hindered phenol antioxidants having a carbonyl group in the extruder increases. When the polypropylene resin composition does not contain a primary agent and contains a hindered phenol antioxidant having a carbonyl group, its content is 6000 mass ppm to 8000 mass ppm or less relative to the mass of the resin component (by mass when the resin component is taken as a whole).

[0376] <Production of Casting Sheets>

[0377] The casting sheet can be obtained as follows: the pellets of the pre-made dry-mixed resin composition and / or the melt-blended resin composition are supplied to the extruder, heated and melted, and after passing through the filter, preferably at 170°C to 320°C, more preferably at 200°C to 300°C, melt-extruded from the T-die, and cooled and solidified on at least one metal drum maintained at a temperature (casting temperature) of preferably 40°C to 140°C, more preferably 80°C to 140°C, further preferably 90 to 140°C, particularly preferably 90 to 120°C, and more particularly preferably 90 to 105°C, so as to obtain. At this time, it is preferred that the resin composition after melt extrusion is pushed to the metal drum with an air knife. It should be noted that the surface on the side in contact with the metal drum becomes the first surface, and the surface on the opposite side (the surface on the air knife side) becomes the second surface.

[0378] The thickness of the cast sheet is not particularly limited as long as the target polypropylene film can be obtained, but is preferably 0.05 mm to 2 mm, more preferably 0.1 mm to 1 mm.

[0379] It should be noted that in the production process of cast sheets (especially in the extruder), polypropylene is greatly subjected to thermal degradation (oxidative degradation) and shear degradation. The degree of such degradation, that is, the change in molecular weight distribution and stereoregularity can be suppressed by nitrogen purging in the extruder (oxidation suppression), the screw shape in the extruder (shear force), the internal shape of the T-die during casting (shear force), the amount of antioxidant added (oxidation suppression), the winding speed during casting (extension force), etc.

[0380] <Stretching treatment>

[0381] The aforementioned biaxially stretched polypropylene film can be manufactured by stretching the aforementioned cast sheet. As a stretching method, a sequential biaxial stretching method is preferred. As a sequential biaxial stretching method, first, the cast sheet is passed through a roller maintained at a temperature of preferably 100 to 180°C, more preferably 140 to 160°C and provided with a speed difference, stretched to 3 to 7 times in the flow direction, and immediately cooled to room temperature. By appropriately adjusting the temperature of the longitudinal stretching process, the β crystal melts and transforms into α crystal, and the concavity and convexity become obvious. Then, the stretched film is introduced into a tenter, and after being stretched to 3 to 11 times in the width direction at a temperature preferably above 160°C, more preferably 160 to 180°C, relaxation, heat setting, and winding into a roll.

[0382] The rolled film is aged in an atmosphere of about 20 to 45° C., and then unwound (unrolled) and slit (cut) into desired product widths using a slitter or the like, and each film is rolled up again.

[0383] Through such a stretching step, a film having excellent mechanical strength and rigidity is obtained, and the surface irregularities are further defined and finely roughened to obtain a biaxially stretched film.

[0384] In the aforementioned polypropylene film, after the stretching and heat setting steps are completed, a corona discharge treatment can be carried out online or offline. By carrying out the corona discharge treatment, the bonding characteristics in subsequent steps such as the metal evaporation processing step can be improved. The corona discharge treatment can be carried out by a known method. It is preferably carried out using air, carbon dioxide gas, nitrogen gas and their mixed gases as the atmosphere gas.

[0385] In order to process into a capacitor, a metal layer can be laminated on one or both sides of the polypropylene film to form a metal layer integrated polypropylene film. The metal layer functions as an electrode. As the metal used in the metal layer, for example, metal single substances such as zinc, lead, silver, chromium, aluminum, copper, nickel, a variety of mixtures thereof, alloys thereof, etc. can be used. If the environment, economy, capacitor performance, etc. are taken into consideration, zinc and aluminum are preferred.

[0386] As a method for laminating a metal layer on one side or both sides of the polypropylene film, for example, a vacuum evaporation method and a sputtering method can be exemplified. From the viewpoints of productivity and economy, the vacuum evaporation method is preferred. As a vacuum evaporation method, generally, a crucible method, a wire method, etc. can be exemplified, and there is no particular limitation, and the best one can be appropriately selected.

[0387] There is no particular limitation on the process margin pattern when stacking metal layers by vapor deposition. From the perspective of improving the safety of the capacitor, it is preferred to apply a fishnet pattern or a T process margin pattern on one side of the film, which includes a so-called special process margin. This is also effective from the perspective of improving safety and preventing capacitor damage and short circuits.

[0388] The method for forming the process margin can be any commonly known method such as a tape method, an oil method, etc. without any limitation.

[0389] When the metal layer is formed on the polypropylene film, the polypropylene film wound into a roll is unwound (unrolled), and a metal layer such as a vapor-deposited film is formed on one surface or both surfaces, and then the film is wound again.

[0390] The metal layer integrated polypropylene film may be laminated in multiple layers by a conventionally known method, or may be wound (reeled) to form a film capacitor.

[0391] Specifically, a blade is placed in the center of each process margin portion of the metal layer integrated polypropylene film to perform slitting processing, thereby manufacturing a winding reel having a process margin on one surface.

[0392] Here, the Spk value (Spk A ), the Spk value of the first side (Spk A ), the Svk value of the second surface (Svk B ) and the Spk value of the second side (Spk B ) is within the specified numerical range, so blocking is suppressed. Therefore, during the above-mentioned slitting process, the polypropylene film is blocked, which can prevent wrinkles in the film in the flow direction.

[0393] Next, using the winding reel with the left process margin and the winding reel with the right process margin, the two sheets are overlapped and wound in such a way that the vapor-deposited portion extends further than the process margin portion in the width direction (element winding process). Next, the core material is extracted from the wound body and pressurized. Next, external electrodes are formed on the two end surfaces, and then leads are set on the external electrodes. Based on the above, a wound film capacitor can be obtained.

[0394] The first embodiment (first embodiment of the present invention) has been described above.

[0395] <Second embodiment of the present invention>

[0396] Next, the second embodiment of the present invention will be described. It should be noted that the polypropylene film of the second embodiment of the present invention has an Svk value (Svk A) does not need to be greater than 0.005 μm and less than 0.030 μm. A ) does not need to exceed 0.035 μm and is 0.080 μm or less. B ) does not need to be greater than 0.005 μm and less than 0.030 μm. B ) does not need to be greater than 0.015 μm and less than 0.035 μm.

[0397] The polypropylene film of the second embodiment of the present invention (hereinafter also referred to as "the second embodiment") is as follows:

[0398] Contains polypropylene resin as the main component,

[0399] The Spk value of the second side (Spk B ) and the Spk value (Spk A ) ratio Spk B / Spk A is 0.490 or more and 0.730 or less,

[0400] The Svk value of the second surface (Svk B ) and the Svk value of the first surface (Svk A ) ratio Svk B / Svk A It is 0.735 or more and 1.250 or less.

[0401] RatioSpk B / Spk A Preferably, it is 0.495 or more, more preferably 0.500 or more, and further preferably 0.505 or more. B / Spk A It is preferably 0.710 or less, more preferably 0.700 or less, and further preferably 0.690 or less.

[0402] RatioSvk B / Svk A It is preferably 0.750 or more, more preferably 0.760 or more, and still more preferably 0.780 or more. B / Svk A It is preferably 1.240 or less, more preferably 1.200 or less, and further preferably 1.150 or less.

[0403] The Svk value of the first surface (Svk A) is not limited, but is preferably 0.005 μm or more, more preferably 0.007 μm or more, further preferably 0.008 μm or more, and particularly preferably 0.009 μm or more. A ) is not limited, but is preferably 0.050 μm or less, more preferably 0.040 μm or less, and further preferably 0.035 μm or less.

[0404] The Svk value of the second surface (Svk B ) is not limited, but is preferably 0.005 μm or more, more preferably 0.007 μm or more, further preferably 0.008 μm or more, and particularly preferably 0.009 μm or more. B ) is not limited, but is preferably 0.050 μm or less, more preferably 0.040 μm or less, further preferably 0.035 μm or less, and particularly preferably 0.030 μm.

[0405] The Spk value of the first surface (Spk A ) is not limited, but is preferably 0.030 μm or more, more preferably 0.040 μm or more, further preferably 0.043 μm or more, and particularly preferably 0.045 μm or more. A ) is not limited, but is preferably 0.090 μm or less, more preferably 0.080 μm or less, and further preferably 0.075 μm or less.

[0406] The Spk value of the second side (Spk B ) is not limited, but is preferably 0.010 μm or more, more preferably 0.015 μm or more, further preferably 0.020 μm or more, and particularly preferably 0.025 μm or more. B ) is not limited, but is preferably 0.060 μm or less, more preferably 0.055 μm or less, and further preferably 0.050 μm or less.

[0407] When a metal layer is formed on one or both of the first and second surfaces and the film is wound, the first surface of the polypropylene film and the second surface are in contact with each other in a state where the metal layer is formed. A ), the Spk value of the first side (Spk A ), the Svk value of the second surface (Svk B ) and the Spk value of the second side (Spk B) is within the above numerical range, making the degree of roughening (including the degree of coarse protrusions) different within the above numerical range. Therefore, the contact area between the first surface and the second surface when the polypropylene film is wound is reduced, and the pores between the first surface and the second surface generated by the appropriate coarse protrusions can be maintained, and the cushioning property is excellent. As a result, it can be seen from the examples that adhesion can be suppressed. In addition, according to the above polypropylene film, as a preferred case, the processability of the slitting process is also excellent.

[0408] In addition, the polypropylene film is usually wound as follows: in order to prevent wrinkles or meandering, multiple conveying rollers are used while applying tension to the polypropylene film. Therefore, the film is wound while both surfaces are in contact with any conveying roller, not just one surface.

[0409] According to the polypropylene film, both sides of the polypropylene film are roughened to the same extent, so when the biaxially stretched polypropylene film is wound into a roll, both sides are suitable for sliding on the conveying roller. As a result, suitable conveying performance can be obtained, wrinkles and winding deviations are suppressed, and the element winding processability becomes good.

[0410] Here, if only the transportability is considered, it is preferable that the roughening degree is the same on the first and second surfaces. However, if the withstand voltage is considered, it is preferable that the roughening degree is different on the first and second surfaces. This point will be described below.

[0411] Generally, for the thickness of the film, when there are uneven surfaces on the surface, the apex of the convex portion is the end of the thickness. That is, when there are uneven surfaces on both the first and second surfaces, the distance from the apex of the convex portion on the first surface to the apex of the convex portion on the second surface is the thickness of the film.

[0412] Here, the thickness of the core portion is the thickness obtained by deducting the height of the convex portion on the first surface and the height of the convex portion on the second surface. Therefore, if a polypropylene film with both surfaces being roughened is formed, the thickness of the core portion becomes thinner, leakage current becomes more likely to occur, and the withstand voltage becomes lower.

[0413] Therefore, in the second embodiment, the following is configured: (1) For the Svk value (Svk A ) and the Svk value of the second surface (Svk B ) are equal, that is, the depth of the valley, which can also be regarded as a roughening index, is equal for the first and second surfaces, and (2) for the coarse protrusions, the Spk value (Spk) of the second surface is set to B ) is less than the Spk value of the first side (Spk A ) to ensure the thickness of the core. Based on the above, the voltage resistance is maintained and the transport performance based on the roughening is also achieved.

[0414] As described above, according to the polypropylene film of the second embodiment, blocking can be suppressed, and further, processability in the slitting process, transportability, and voltage resistance can be achieved at the same time.

[0415] The Svk value of the first surface (Svk A ), the Spk value of the first surface (Spk A ), the Svk value of the second surface (Svk B ) and the Spk value of the second side mentioned above (Spk B ) is obtained as follows: using an optical interference type non-contact surface shape measuring machine, using a three-dimensional surface roughness evaluation method, measuring the surface shape, thereby obtaining. "Three-dimensional surface roughness evaluation method" is to evaluate the height of the entire surface of the film, and therefore, the shape of the film surface is evaluated in a three-dimensional manner. Therefore, the local subtle changes and variations of the measured object surface can be grasped, and a more accurate surface roughness can be evaluated. The average height of the three-dimensional protruding mountain portion and the average height of the protruding valley portion are used instead of the height of the simple protrusion (based on the two-dimensional surface roughness evaluation of the general center line average roughness Ra, etc.), the film surface roughness is evaluated, so that adhesion can be suppressed. In addition, a structure having good slitting process processability, conveyability and voltage resistance can be formed.

[0416] More specifically, the Svk value (Svk A ), the Spk value of the first surface (Spk A ), the Svk value of the second surface (Svk B ) and the Spk value of the second side mentioned above (Spk B ) is a value measured using "VertScan2.0 (Model: R5500GML)" manufactured by Ryoka Systems Inc. as an optical interference type non-contact surface profile measuring machine.

[0417] The following describes the details of the measurement method.

[0418] First, using the WAVE mode, a 530 white filter and a 1×BODY lens tube, and a ×10 objective lens, measurements of 470.92 μm × 353.16 μm were performed in each field of view. This was performed at 10 locations at 1 cm intervals from the center in the flow direction and width direction of the target sample (polypropylene film) along the flow direction.

[0419] Next, the obtained data was subjected to noise removal processing using a median filter (3×3), and then subjected to Gaussian filter processing using a cutoff value of 30 μm to remove the curvature component. This enabled the roughened surface state to be appropriately measured.

[0420] Next, use the "ISO parameters" in the "bearing" plug-in function of the "VS-Viewer" analysis software of "VertScan2.0" for analysis.

[0421] Finally, for each value (Svk A 、Spk A , Svk B 、Spk B , Sq A , Sq B , Sa A , Sa B ,Sk A ,Sk B ), and calculate the average value respectively. Based on the above, the Svk value (Svk A ), the Spk value of the first surface (Spk A ), the Svk value of the second surface (Svk B ) and the Spk value of the second side mentioned above (Spk B ). In addition, Sq can also be obtained in the same way. A , Sq B , Sa A , Sa B ,Sk A ,Sk B .

[0422] More specifically, it is based on the method described in Examples.

[0423] The Sq value (Sq B ) and the Sq value of the first surface (Sq A ) ratio Sq B / Sq A , the aforementioned Sq A , the aforementioned Sq B 、Sa value of the second side (Sa B ) and the Sa value of the first side (Sa A ) ratio Sa B / Sa A , the aforementioned Sa A , the aforementioned Sa B 、Sk value of the second surface (Sk B ) and the Sk value of the first surface (Sk A ) ratio Sk B / Sk A , the aforementioned Sk A , the aforementioned Sk BIt is preferably within the numerical range described in the section “First embodiment of the present invention.” Note that the meanings and methods of obtaining these parameters are described in the section “First embodiment of the present invention,” and therefore, descriptions thereof are omitted here.

[0424] For the Svk value (Svk A ), the Spk value of the first surface (Spk A ), the Svk value of the second surface (Svk B ), the Spk value of the second surface (Spk B ), the aforementioned ratio Spk B / Spk A , the aforementioned ratio Svk B / Svk A , the Sq value of the first surface (Sq A ), the Sq value of the second surface (Sq B ), the aforementioned ratio Sq B / Sq A , the Sa value of the first surface (Sa A ), the Sa value of the second surface (Sa B ), the aforementioned ratio Sa B / Sa A , the Sk value of the first surface (Sk A ), the Sk value of the second surface (Sk B ) and the aforementioned ratio Sk B / Sk A The method of keeping the above numerical range is not particularly limited, and can be based on (i) the type of resin (raw material resin) constituting the above polypropylene film, stereoregularity, molecular weight distribution and differential distribution value difference D M , (ii) the content of each resin relative to the overall polypropylene film, (iii) the longitudinal and transverse stretching ratios during stretching, and the stretching temperature, (iv) the type of additives (especially nucleating agents) and their content, etc. are appropriately adjusted.

[0425] As the Svk value (Svk A ) and the Svk value of the second surface mentioned above (Svk B ) different methods, so that the Spk value (Spk A ) and the Spk value (Spk B ) different methods, so that the Sq value of the first surface (Sq A ) and the Sq value of the second surface (Sq B ) different methods, so that the Sa value (Sa A ) and the Sa value of the second surface (Sa B) different methods, making the Sk value (Sk A ) and the Sk value of the second surface (Sk B ) Different methods are not particularly limited. For example, the first surface is used as the surface on the casting roll side and the second surface is used as the surface on the air knife side to make a casting sheet, and the casting sheet is biaxially stretched to achieve adjustment.

[0426] Both surfaces of the polypropylene film may be roughened by crater-like fine irregularities. The crater-like fine irregularities have been described in the section "First Embodiment of the Invention", and therefore, description thereof will be omitted here.

[0427] The polypropylene film preferably has an elliptical density D of the first surface. A 50~120 pieces / mm 2 In addition, the ellipse density D of the second surface B Preferably lower than the above D A In addition, the ellipse density D of the second surface B Preferably 1 to 90 pieces / mm 2 .

[0428] The aforementioned ellipse density D A More preferably 85 to 120 pieces / mm 2 , more preferably 90 to 105 pieces / mm 2 .

[0429] The aforementioned ellipse density D B More preferably, 1 to 12 pieces / mm 2 , more preferably 3 to 11 pieces / mm 2 , particularly preferably 4 to 10 pieces / mm 2 .

[0430] The method of obtaining the elliptic density has been described in the section "First embodiment of the present invention", and therefore the description here is omitted.

[0431] If the ellipse density D of the first surface A 50~120 pieces / mm 2 , the ellipse density D of the second surface B 1~90 / mm 2 , the contact area between the first surface and the second surface when the polypropylene film is wound can be further reduced.

[0432] Specifically, the ellipse density D of the first surface is A 50~120 pieces / mm 2 In the case of , it can be said that the number of "ellipses" is large. Therefore, the roughening is performed more. On the other hand, the ellipse density D of the second surface is BIf 1 to 90 pieces / mm 2 , it can be said that the number of "ovals" is small. Therefore, although it is roughened, the degree is small.

[0433] In this way, if the ellipse density D of the first surface is A 50~120 pieces / mm 2 , and the ellipse density D of the second surface B 1~90 / mm 2 , it is possible to suppress the film from slitting to the left and right during the slitting process, and the end surface of the small roll becomes uneven. As a result, it is known from the embodiment that the slitting process can be made good.

[0434] In addition, if the ellipse density D of the first surface A 50~120 pieces / mm 2 , the ellipse density D of the second surface B 1~90 / mm 2 , both sides of the polypropylene film are more appropriately roughened, so that when the biaxially stretched polypropylene film is wound into a roll, the sliding properties of the conveying rollers are more suitable on both sides. As a result, more suitable conveying properties can be obtained, and wrinkles and winding deviations are further suppressed.

[0435] Here, if only the transportability is considered, it is preferable that the roughening degree is the same on the first and second surfaces. However, if the withstand voltage is considered, it is preferable that the roughening degree is different on the first and second surfaces. Generally, if the surface is roughened, the thinner part of the film (the concave part of the concave-convex part) becomes the cause of leakage current. Therefore, if the ellipticity D of the second surface is increased, B Smaller than the ellipse density D of the first surface A , the number of concave and convex surfaces that may cause leakage current can be reduced. Specifically, the ellipse density D of the second surface is B If 1 to 90 pieces / mm 2 As a result, the structure can more appropriately maintain the withstand voltage and more appropriately have the transport performance due to the roughening.

[0436] The elliptical density D of the first surface of the polypropylene film is A The average major axis length L of the ellipse A , the ellipse density D constituting the second surface B The average major axis length L of the ellipse B , the ellipse density D constituting the first surface A The ellipse perfection P of the ellipse A , the ellipse density D constituting the second surface B The ellipse perfection P of the ellipseB It is preferably within the numerical range described in the section “First embodiment of the present invention.” Note that the meanings and methods of obtaining these parameters are described in the section “First embodiment of the present invention,” and therefore, descriptions thereof are omitted here.

[0437] The DC dielectric breakdown strength ES of the polypropylene film at 100° C. and the DC dielectric breakdown strength ES of the polypropylene film at 120° C. are preferably within the numerical ranges described in the section “First embodiment of the present invention”.

[0438] The ash content of the polypropylene film is preferably within the numerical range described in the section "First embodiment of the present invention." The method for obtaining the ash content is described in the section "First embodiment of the present invention," and therefore, the description here is omitted.

[0439] The thickness of the polypropylene film is preferably within the numerical range described in the section "First embodiment of the present invention." The method for obtaining the thickness is described in the section "First embodiment of the present invention," and therefore, the description here is omitted.

[0440] The polypropylene film may be a biaxially stretched film, a uniaxially stretched film, or an unstretched film. A ), the Spk value of the first surface (Spk A ), the Svk value of the second surface (Svk B ) and the Spk value of the second side mentioned above (Spk B ) is within the aforementioned numerical range, a biaxially stretched film is preferred.

[0441] The aforementioned polypropylene film and the metal layer integrated polypropylene film are respectively wound into rolls in advance, preferably in the form of film rolls. The aforementioned film roll may have a roll core (core) or may not have a roll core (core). The aforementioned film roll preferably has a roll core (core). There is no particular limitation on the material of the roll core of the aforementioned film roll. As the aforementioned material, the material of the roll core described in the item "First embodiment of the present invention" can be used.

[0442] As described above, the polypropylene film contains a polypropylene resin as a main component. As the polypropylene resin, the polypropylene resin described in the section "First Embodiment of the Invention" can be used.

[0443] The polypropylene film may contain other resins in addition to the polypropylene resin. In addition, the polypropylene film may further contain at least one additive on the basis of the resin component. As the other resin and the additive, the polypropylene resin described in the item "First Embodiment of the Invention" may be used.

[0444] The polypropylene film is preferably biaxially stretched. When the polypropylene film is a biaxially stretched polypropylene film, the biaxially stretched polypropylene film can be produced by a commonly known method for producing a biaxially stretched polypropylene film. For example, a linear polypropylene resin A, a linear polypropylene resin B, and a long-chain branched polypropylene resin C are mixed with other resins, additives, etc. as needed to obtain a polypropylene resin composition, and a casting sheet is prepared from the obtained polypropylene resin composition. Then, the casting sheet is biaxially stretched to produce the film.

[0445] <Preparation of polypropylene resin composition>

[0446] As a method for preparing the polypropylene resin composition, the method described in the section "First embodiment of the present invention" can be adopted.

[0447] <Production of Casting Sheets>

[0448] As a method for producing the cast sheet, the method described in the section "First embodiment of the present invention" can be adopted.

[0449] <Stretching treatment>

[0450] The biaxially stretched polypropylene film can be produced by stretching the cast sheet. The stretching method may be the method described in the section "First Embodiment of the Invention".

[0451] The polypropylene film may be subjected to a corona discharge treatment in-line or off-line after the stretching and heat setting steps. The corona discharge treatment may be performed by the method described in the section "First Embodiment of the Invention".

[0452] In order to process into a capacitor, a metal layer can be laminated on one or both sides of the polypropylene film to form a metal layer integrated polypropylene film. The material and lamination method of the metal layer can adopt the contents described in the first embodiment of the present invention.

[0453] The metal layer integrated polypropylene film can be laminated in multiple layers by a conventionally known method, or can be wound (reeled) to form a film capacitor.

[0454] As a specific method for manufacturing the thin film capacitor, the method described in the section "First Embodiment of the Invention" can be adopted.

[0455] The second embodiment (the second embodiment of the present invention) has been described above.

[0456] <Third Embodiment of the Invention>

[0457] Next, the third embodiment of the present invention will be described. It should be noted that the polypropylene film of the third embodiment of the present invention has an Svk value (Svk A ) does not need to be greater than 0.005 μm and less than 0.030 μm. A ) does not need to exceed 0.035 μm and is 0.080 μm or less. B ) does not need to be greater than 0.005 μm and less than 0.030 μm. B ) does not need to be greater than 0.015 μm and less than 0.035 μm.

[0458] In addition, the polypropylene film according to the third embodiment of the present invention has a Spk value (Spk B ) and the Spk value of the first side (Spk A ) ratio Spk B / Spk A It does not need to be greater than 0.490 and less than 0.730. B ) and the Svk value of the first surface (Svk A ) ratio Svk B / Svk A It does not need to be 0.735 or more and 1.250 or less.

[0459] The polypropylene film of the third embodiment of the present invention (hereinafter also referred to as "the third embodiment") is as follows:

[0460] has a first side and a second side, and

[0461] Contains polypropylene resin as the main component,

[0462] The ellipse density D of the first surface A 85~120 pieces / mm 2 ,

[0463] The ellipse density D of the second surface mentioned above B 1~12 pieces / mm 2 .

[0464] The aforementioned ellipse density D A More preferably 85 to 110 pieces / mm 2 , more preferably 90 to 105 pieces / mm 2 .

[0465] The aforementioned ellipse density D B More preferably, 3 to 11 pieces / mm 2, more preferably 4 to 10 pieces / mm 2 .

[0466] Both surfaces of the polypropylene film may be roughened by crater-like fine irregularities. The crater-like fine irregularities have been described in the section "First Embodiment of the Invention", and therefore, description thereof will be omitted here.

[0467] The ellipse density D of the first surface A 85~120 pieces / mm 2 , the ellipse density D of the second surface B 1~12 pieces / mm 2 Therefore, the contact area between the first surface and the second surface when the polypropylene film is wound becomes smaller, and the pores between the first surface and the second surface generated by the difference in elliptical density can be maintained, and the cushioning property is excellent. As a result, it can be seen from the examples that blocking can be suppressed.

[0468] In addition, the ellipse density D of the first surface A 85~120 pieces / mm 2 , it can be said that the number of "ovals" is large. Therefore, the roughening is performed more. On the other hand, the ellipse density D of the second surface is B 1~12 pieces / mm 2 , it can be said that the number of "ovals" is small. Therefore, although it is roughened, the degree is small.

[0469] In this way, if the ellipse density D of the first surface is A 85~120 pieces / mm 2 , and the ellipse density D of the second surface B 1~12 pieces / mm 2 , it is possible to suppress the film from meandering to the left and right during the slitting process, and the end surface of the small roll becomes uneven. As a result, it is known from the embodiment that the slitting process can be made good in processability.

[0470] In addition, the polypropylene film is usually wound as follows: in order to prevent wrinkles or meandering, multiple conveying rollers are used while applying tension to the polypropylene film. Therefore, the film is wound while both surfaces are in contact with any conveying roller, not just one surface.

[0471] According to the polypropylene film, both sides of the polypropylene film are roughened, so when the biaxially stretched polypropylene film is wound into a roll, both sides are suitable for sliding on the conveying roller. As a result, suitable conveying performance can be obtained, and wrinkles and winding deviations are suppressed.

[0472] Specifically, the ellipse density D of the first surface is A 85~120 pieces / mm2 , the ellipse density D of the second surface B 1~12 pieces / mm 2 Therefore, both sides of the polypropylene film are appropriately roughened, so that when the biaxially stretched polypropylene film is wound into a roll, both sides are suitable for sliding on the conveying roller. As a result, suitable conveying performance can be obtained, wrinkles and winding deviations are further suppressed, and the element winding processability becomes good.

[0473] Here, if only the transportability is considered, it is preferable that the roughening degree is the same on the first and second surfaces. However, if the withstand voltage is considered, it is preferable that the roughening degree is different on the first and second surfaces. Generally, if the surface is roughened, the thinner part of the film (the concave part of the concave-convex part) becomes the cause of leakage current. Therefore, if the ellipticity D of the second surface is increased, B Smaller than the ellipse density D of the first surface A , the number of concave and convex surfaces that may cause leakage current can be reduced. Specifically, the ellipse density D of the second surface is B If 1 to 12 pieces / mm 2 , it can be said that the number of concavities and convexities that may cause leakage current is small. As a result, the structure is formed to appropriately maintain the withstand voltage and more appropriately have the transport property due to the roughening.

[0474] As described above, according to the polypropylene film of the third embodiment, blocking can be suppressed, and further, processability in the slitting process, transportability, and voltage resistance can be achieved at the same time.

[0475] The method of obtaining the elliptic density has been described in the section "First embodiment of the present invention", and therefore the description here is omitted.

[0476] The elliptical density D of the first surface of the polypropylene film is A The average major axis length L of the ellipse A , the ellipse density D constituting the second surface B The average major axis length L of the ellipse B , the ellipse density D constituting the first surface A The ellipse perfection P of the ellipse A , the ellipse density D constituting the second surface B The ellipse perfection P of the ellipse B It is preferably within the numerical range described in the section “First embodiment of the present invention.” Note that the meanings and methods of obtaining these parameters are described in the section “First embodiment of the present invention,” and therefore, descriptions thereof are omitted here.

[0477] The Sq value (Sq B) and the Sq value of the first surface (Sq A ) ratio Sq B / Sq, the aforementioned Sq A , the aforementioned Sq B 、Sa value of the second side (Sa B ) and the Sa value of the first side (Sa A ) ratio Sa B / Sa A , the aforementioned Sa A , the aforementioned Sa B 、Sk value of the second surface (Sk B ) and the Sk value of the first surface (Sk A ) ratio Sk B / Sk A , the aforementioned Sk A , the aforementioned Sk B It is preferably within the numerical range described in the section “First embodiment of the present invention.” Note that the meanings and methods of obtaining these parameters are described in the section “First embodiment of the present invention,” and therefore, descriptions thereof are omitted here.

[0478] For the ellipse density D of the first surface A , the ellipse density D of the second surface B , the ellipse density D constituting the first surface A The average major axis length L of the ellipse A , the ellipse density D constituting the second surface B The average major axis length L of the ellipse B , the Sq value of the first surface (Sq A ), the Sq value of the second surface (Sq B ), the aforementioned ratio Sq B / Sq A , the Sa value of the first surface (Sa A ), the Sa value of the second surface (Sa B ), the aforementioned ratio Sa B / Sa A , the Sk value of the first surface (Sk A ), the Sk value of the second surface (Sk B ) and the aforementioned ratio Sk B / Sk A The method of keeping the above numerical range is not particularly limited, and can be based on (i) the type of resin (raw material resin) constituting the above polypropylene film, stereoregularity, molecular weight distribution and differential distribution value difference D M, (ii) the content of each resin relative to the overall polypropylene film, (iii) the longitudinal and transverse stretching ratios during stretching, and the stretching temperature, (iv) the type of additives (especially nucleating agents) and their content, etc. are appropriately adjusted.

[0479] As the ellipse density D of the first surface A The ellipse density D of the second surface mentioned above B Different methods, make the ellipse density D constituting the first surface A The average major axis length L of the ellipse A The ellipse density D constituting the second surface B The average major axis length L of the ellipse B Different methods, make the Sq value (Sq A ) and the Sq value of the second surface (Sq B ) different methods, so that the Sa value (Sa A ) and the Sa value of the second surface (Sa B ) different methods, making the Sk value (Sk A ) and the Sk value of the second surface (Sk B ) Different methods are not particularly limited. For example, the first surface is used as the surface on the casting roll side and the second surface is used as the surface on the air knife side to make a casting sheet, and the casting sheet is biaxially stretched to achieve adjustment.

[0480] The DC dielectric breakdown strength ES of the polypropylene film at 100° C. and the DC dielectric breakdown strength ES of the polypropylene film at 120° C. are preferably within the numerical ranges described in the section “First embodiment of the present invention”.

[0481] The ash content of the polypropylene film is preferably within the numerical range described in the section "First embodiment of the present invention." The method for obtaining the ash content is described in the section "First embodiment of the present invention," and therefore, the description here is omitted.

[0482] The thickness of the polypropylene film is preferably within the numerical range described in the section "First embodiment of the present invention." The method for obtaining the thickness is described in the section "First embodiment of the present invention," and therefore, the description here is omitted.

[0483] The polypropylene film may be a biaxially stretched film, a uniaxially stretched film, or an unstretched film. A and the aforementioned ellipse density D B From the viewpoint of being within the aforementioned numerical range, a biaxially stretched film is preferred.

[0484] The aforementioned polypropylene film and the metal layer integrated polypropylene film are respectively wound into rolls in advance, preferably in the form of film rolls. The aforementioned film roll may have a roll core (core) or may not have a roll core (core). The aforementioned film roll preferably has a roll core (core). There is no particular limitation on the material of the roll core of the aforementioned film roll. As the aforementioned material, the material of the roll core described in the item "First embodiment of the present invention" can be used.

[0485] As described above, the polypropylene film contains a polypropylene resin as a main component. As the polypropylene resin, the polypropylene resin described in the section "First Embodiment of the Invention" can be used.

[0486] The polypropylene film may contain other resins in addition to the polypropylene resin. In addition, the polypropylene film may further contain at least one additive on the basis of the resin component. As the other resin and the additive, the polypropylene resin described in the item "First Embodiment of the Invention" may be used.

[0487] The polypropylene film is preferably biaxially stretched. When the polypropylene film is a biaxially stretched polypropylene film, the biaxially stretched polypropylene film can be produced by a commonly known method for producing a biaxially stretched polypropylene film. For example, a linear polypropylene resin A, a linear polypropylene resin B, and a long-chain branched polypropylene resin C are mixed with other resins, additives, etc. as needed to obtain a polypropylene resin composition, a casting sheet is prepared from the obtained polypropylene resin composition, and then the casting sheet is biaxially stretched to produce the film.

[0488] <Preparation of polypropylene resin composition>

[0489] As a method for preparing the polypropylene resin composition, the method described in the section "First embodiment of the present invention" can be adopted.

[0490] <Production of Casting Sheets>

[0491] As a method for producing the cast sheet, the method described in the section "First embodiment of the present invention" can be adopted.

[0492] <Stretching treatment>

[0493] The biaxially stretched polypropylene film can be produced by stretching the cast sheet. The stretching method may be the method described in the section "First Embodiment of the Invention".

[0494] The polypropylene film may be subjected to a corona discharge treatment in-line or off-line after the stretching and heat setting steps. The corona discharge treatment may be performed by the method described in the section "First Embodiment of the Invention".

[0495] In order to process into a capacitor, a metal layer may be laminated on one or both sides of the polypropylene film to form a metal layer integrated polypropylene film. The material and lamination method of the metal layer may be the same as those described in the first embodiment of the present invention.

[0496] The metal layer integrated polypropylene film can be laminated in multiple layers by a conventionally known method, or can be wound (reeled) to form a film capacitor.

[0497] Specifically, a blade is placed in the center of each process margin portion of the metal layer integrated polypropylene film to perform slitting processing, thereby manufacturing a winding reel having a process margin on one surface.

[0498] Here, the elliptical density D of the polypropylene film is A and the aforementioned ellipse density D B The polypropylene film is blocked during the slitting process, and wrinkles in the flow direction of the film can be prevented from forming.

[0499] Next, using the winding reel with the left process margin and the winding reel with the right process margin, the two sheets are overlapped and wound in such a way that the vapor-deposited portion extends further than the process margin portion in the width direction (element winding process). Next, the core material is extracted from the wound body and pressurized. Next, external electrodes are formed on both end surfaces, and further, leads are set on the external electrodes. Based on the above, a wound film capacitor can be obtained.

[0500] In the above, the third embodiment of the present invention has been described.

[0501] Example

[0502] Hereinafter, the present invention (the first present invention, the second present invention, and the third present invention) will be described in detail using embodiments, but the present invention (the first present invention, the second present invention, and the third present invention) is not limited to the following embodiments as long as the gist thereof is not exceeded.

[0503] <First embodiment of the present invention>

[0504] Hereinafter, first, a first embodiment of the present invention will be described.

[0505] 〔Polypropylene resin〕

[0506] Table 1 shows the polypropylene resins used to produce the polypropylene films of Examples and Comparative Examples.

[0507] Resin A1 shown in Table 1 is a product manufactured by Prime Polymer Co., Ltd. Resin A2 is a product manufactured by Prime Polymer Co., Ltd. Resin B1 is S802M manufactured by Korea Petrochemical Corporation. Resin B2 is HPT-1 manufactured by Korea Petrochemical Corporation. Resin B3 is manufactured by Korea Petrochemical Corporation. Resin C1 is MFX6 manufactured by Japan Polypropylene Corporation. Resin X1 is WB135HMS (Daploy HMS-PP) manufactured by Borealis. It should be noted that MFX6 is a long-chain branched polypropylene resin obtained by polymerization using a metallocene catalyst. WB135HMS is a long-chain branched polypropylene resin obtained by cross-linking modification with peroxide. Resin A1 and Resin A2 are equivalent to linear polypropylene resin A. Resin B1, Resin B2, and Resin B3 are equivalent to linear polypropylene resin B. Resin C1 is equivalent to long-chain branched polypropylene resin C. Resin A1, Resin A2, Resin B1, Resin B2, and Resin B3 are all homopolypropylene resins. Resin X2 is a product manufactured by Prime Polymer Co., Ltd. and is a linear homopolypropylene.

[0508] Table 1 shows the number average molecular weight (Mn), weight average molecular weight (Mw), z average molecular weight (Mz), molecular weight distribution (Mw / Mn), and molecular weight distribution (Mz / Mn) of each resin. These values ​​are values ​​in the form of raw material resin pellets. The measurement method is as follows.

[0509] <Measurement of number average molecular weight (Mn), weight average molecular weight (Mw), z average molecular weight (Mz), molecular weight distribution (Mw / Mn) and molecular weight distribution (Mz / Mn) of linear polypropylene resin>

[0510] The number average molecular weight (Mn), weight average molecular weight (Mw), z average molecular weight (Mz), molecular weight distribution (Mw / Mn) and molecular weight distribution (Mz / Mn) of each resin were measured under the following conditions using GPC (gel permeation chromatography).

[0511] Specifically, a high temperature GPC device HLC-8121GPC-HT type 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, trichlorobenzene as an eluent was allowed to flow at a flow rate of 1.0 ml / min and measured. Using standard polystyrene manufactured by Tosoh Corporation, a standard curve involving its molecular weight M was prepared, and using the Q-factor, the measured value was converted to the molecular weight of polypropylene to obtain a number average molecular weight (Mn), a weight average molecular weight (Mw) and a z average molecular weight (Mz). Using the values ​​of the Mw and Mn, a molecular weight distribution (Mw / Mn) was obtained. In addition, using the values ​​of the Mz and Mn, a molecular weight distribution (Mz / Mn) was obtained.

[0512] <Determination of number average molecular weight (Mn), weight average molecular weight (Mw), z average molecular weight (Mz), molecular weight distribution (Mw / Mn) and molecular weight distribution (Mz / Mn) of long chain branched polypropylene>

[0513] The number average molecular weight (Mn), weight average molecular weight (Mw), z average molecular weight (Mz), molecular weight distribution (Mw / Mn), and molecular weight distribution (Mz / Mn) of polypropylene were measured using GPC (gel permeation chromatography) under the following conditions.

[0514] A high-temperature GPC device HLC-8121GPC-HT type 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 further, one TSKgelguardcolumn HHR(30) was used. At a column temperature of 140°C, 0.05wt% of 2,6-di-tert-butyl-p-cresol (common name: BHT) dissolved in 1,2,4-trichlorobenzene was used as an eluent and flowed at a flow rate of 1.0ml / min to obtain the number average molecular weight (Mn), weight average molecular weight (Mw) and z average molecular weight (Mz). Using the values ​​of Mz and Mn, the molecular weight distribution (Mz / Mn) was obtained. In addition, using the values ​​of Mw and Mn, the molecular weight distribution (Mw / Mn) was obtained. The measurement conditions are as described below.

[0515] GPC device: HLC-8121GPC / HT (made by Tosoh)

[0516] Light scattering detector: DAWN EOS (Wyatt Technology Co., Ltd.), column: TSK gel guard column HHR (30) (7.8 mm ID × 7.5 cm) × 1 + TSK gel GMHHR-H (20) HT (7.8 mm ID × 30 cm) × 3 (Tosoh Corporation)

[0517] Eluent: 0.05 wt% BHT dissolved in 1,2,4-trichlorobenzene

[0518] Flow rate: 1.0mL / min

[0519] Sample concentration: 2mg / mL

[0520] Injection volume: 300μL

[0521] Column temperature: 140°C

[0522] System temperature: 40℃

[0523] Pretreatment: The sample was accurately weighed, and an eluent was added, and the sample was shaken and dissolved at 140°C for 1 hour, and then hot filtered using a 0.5 μm sintered metal filter.

[0524] <Differential distribution value when logarithmic molecular weight log(M) = 4.5, differential distribution value when logarithmic molecular weight log(M) = 6.0, and differential distribution value difference D M Determination of >

[0525] For each resin, the differential distribution value when the logarithmic molecular weight log(M) = 4.5 and the differential distribution value when the logarithmic molecular weight log(M) = 6.0 are obtained by the following method. First, the time curve (dissolution curve) of the intensity distribution detected by the RI detector is converted into a distribution curve of the molecular weight M (Log(M)) relative to the standard polystyrene using the standard curve prepared using the above-mentioned standard polystyrene. Next, after obtaining the integral distribution curve relative to Log(M) when the entire area of ​​the distribution curve is set to 100%, the integral distribution curve is differentiated by Log(M) to obtain the differential distribution curve relative to Log(M). From the differential distribution curve, the differential distribution values ​​when Log(M) = 4.5 and Log(M) = 6.0 are read. In addition, the difference between the differential distribution value when Log(M) = 4.5 and the differential distribution value when Log(M) = 6.0 is taken as the differential distribution value difference D M It should be noted that a series of operations until the differential distribution curve was obtained were performed using analysis software built into the GPC measurement device used. The results are shown in Table 1.

[0526] <Measurement of Melt Flow Rate (MFR)>

[0527] For each resin, the melt flow rate (MFR) in the form of raw resin pellets was measured using a melt indexer of Toyo Seiki Co., Ltd. according to condition M of JIS K 7210. Specifically, first, a sample weighing 4 g was inserted into a barrel at a test temperature of 230°C and preheated for 3.5 minutes under a load of 2.16 kg. Thereafter, the weight of the sample extruded from the bottom hole in 30 seconds was measured to determine the MFR (g / 10 minutes). The above measurement was repeated 3 times, and the average value was taken as the measured value of the MFR. The results are shown in Table 1.

[0528] <Determination of heptane-insoluble matter (HI)>

[0529] Each resin was press-molded into a size of 10 mm × 35 mm × 0.3 mm to prepare a sample for measurement of about 3 g. Then, about 150 mL of heptane was added and Soxhlet extraction was performed for 8 hours. The heptane-insoluble matter was calculated from the sample mass before and after extraction. The results are shown in Table 1.

[0530] <Determination of ash content>

[0531] The ash content of each resin was measured as follows.

[0532] About 200 g of the sample was weighed, transferred to a platinum dish, and ash was burned at 800° C. for 40 minutes. The ash content (ppm) was measured from the obtained ash residue. The results are shown in Table 1.

[0533] <Meso pentad component rate>

[0534] Each resin was dissolved in a solvent, and the measurement was performed using a high temperature Fourier transform nuclear magnetic resonance apparatus (high temperature FT-NMR) under the following conditions.

[0535] High-temperature nuclear magnetic resonance (NMR) device: JEOL Ltd. High-temperature Fourier transform nuclear magnetic resonance device (high-temperature FT-NMR), JNM-ECP500

[0536] Observation nucleus: 13C (125MHz)

[0537] Measuring temperature: 135℃

[0538] Solvent: o-dichlorobenzene (ODCB: a mixed solvent of ODCB and deuterated ODCB (mixing ratio = 4 / 1))

[0539] Measurement mode: Single pulse proton broadband decoupling

[0540] Pulse width: 9.1μsec (45° pulse)

[0541] Pulse interval: 5.5 seconds

[0542] Cumulative times: 4500 times

[0543] Shift standard: CH3(mmmm)=21.7ppm

[0544] The pentad ratio indicating stereoregularity is calculated as a percentage (%) based on the intensity integral value of each signal of the combination of five pentads (pentads) (mmmm, mrrm, etc.) derived from the unit group "meso (m)" arranged in the same direction and the unit group "racemic (r)" arranged in different directions. For the attribution of each signal derived from mmmm, mrrm, etc., for example, the description of the spectrum such as "T. Hayashi et al., Polymer, Vol. 29, p. 138 (1988)" is used as a reference.

[0545] [Table 1]

[0546]

[0547] Using the above resins, polypropylene films of Examples and Comparative Examples were produced, and their physical properties were evaluated.

[0548] <Production of polypropylene film>

[0549] (Example 1)

[0550] Resin A1, resin B1 and resin C1 are dry-blended. The mixing ratio is set to (resin A1): (resin B1): (resin C1) = 63:34:3 in terms of mass ratio. After that, the dry-blended resin is melted at a resin temperature of 250°C, extruded using a T-die, wound on a metal drum maintained at a surface temperature of 95°C and solidified to prepare a cast sheet. At this time, the cast sheet is prepared while the molten extruded resin composition is pushed to the metal drum with an air knife. The obtained unstretched cast sheet is passed between rollers maintained at a temperature of 130°C and provided with a speed difference, stretched to 4.5 times in the flow direction, and immediately cooled to room temperature. Then, the stretched film is introduced into a tenter, stretched to 8 times in the width direction at a temperature of 158°C, relaxed, heat-set, and wound up, and aged in an atmosphere of about 40°C to obtain the polypropylene film of Example 1.

[0551] (Example 2 to Example 5, Comparative Example 1 to Comparative Example 6)

[0552] Except that the mixing ratio when dry-blending the raw material resins was changed as shown in Table 2, the polypropylene films of Examples 2 to 5 and Comparative Examples 1 to 6 were obtained in the same manner as in Example 1.

[0553] However, in Comparative Example 6, a smooth cast sheet could not be produced due to melt fracture during extrusion molding. Therefore, the cast sheet was broken when stretched.

[0554] (Example 6 to Example 8, Comparative Example 7, Comparative Example 8)

[0555] Except that the mixing ratio when dry-blending the raw material resins was changed as shown in Table 2, the polypropylene films of Examples 6 to 8 and Comparative Examples 7 and 8 were obtained in the same manner as in Example 1.

[0556] [Table 2]

[0557]

[0558] <Measurement of thickness of polypropylene film>

[0559] The thickness of the polypropylene films of Examples and Comparative Examples was measured. Specifically, the thickness was measured at 100±10 kPa using a paper thickness measuring instrument MEI-11 manufactured by CITIZEN SEIMITSU CO., LTD., and other conditions were measured in accordance with JIS-C2330. The results are shown in Table 3.

[0560] <Svk value of the first surface (Svk A ), the Spk value of the first side (Spk A ), the Svk value of the second surface (Svk B ), the Spk value of the second side (Spk B ), the Sq value of the first side (Sq A ), the Sq value of the second side (Sq B ), the Sa value of the first side (Sa A ), the Sa value of the second side (Sa B ), the Sk value of the first surface (Sk A ) and the Sk value of the second surface (Sk B ) determination>

[0561] Hereinafter, the first surface may be referred to as “surface A” and the second surface may be referred to as “surface B”. In Table 3, the terms “surface A” and “surface B” may also be used.

[0562] As an optical interference type non-contact surface profile measuring machine, “VertScan 2.0 (model: R5500GML)” manufactured by Ryoka Systems Inc. was used.

[0563] First, using the WAVE mode, a 530 white filter and a 1×BODY lens tube, and a ×10 objective lens, measurements of 470.92 μm × 353.16 μm were performed in each field of view. This was performed at 10 locations at 1 cm intervals from the center in the flow direction and width direction of the target sample (polypropylene film) along the flow direction.

[0564] Next, the obtained data was subjected to noise removal processing using a median filter (3×3), and then subjected to Gaussian filter processing using a cutoff value of 30 μm to remove the curvature component. This enabled the roughened surface state to be appropriately measured.

[0565] Next, use the "ISO parameters" in the "bearing" plug-in function of the "VS-Viewer" analysis software of "VertScan2.0" for analysis.

[0566] Finally, for each value (Svk A 、Spk A , Svk B 、Spk B , Sq A , Sq B , Sa A , Sa B ,Sk A ,Sk B ), and calculate the average value respectively. Based on the above, determine the Svk value (Svk A ), the Spk value of the first side (Spk A ), the Svk value of the second surface (Svk B ), the Spk value of the second side (Spk B ), the Sq value of the first side (Sq A ), the Sq value of the second side (Sq B ), the Sa value of the first side (Sa A ), the Sa value of the second side (Sa B ), the Sk value of the first surface (Sk A ) and the Sk value of the second surface (Sk B ). The results are shown in Table 3. It should be noted that in Table 3, the ratio Sq B / Sq A , than Sa B / Sa A , than Sk B / Sk A The value of .

[0567] <Measurement of elliptic density>

[0568] The ellipse density of the first surface (surface A) and the second surface (surface B) of the polypropylene film of the embodiment and the comparative example was measured. Specifically, a digital oscilloscope (digital microscope VHX-2000 manufactured by Keyence Corporation) was used to observe each surface of the polypropylene film at a lens magnification of 100 times, a measurement method: reflection measurement, and a field of view of 3.4 mm × 2.6 mm, and the number of "ellipses" observed within the field of view was measured. Afterwards, it was converted to per unit area. The results are shown in Table 3.

[0569] It should be noted that, when the length of one axis is L μm and the length of the other axis is S μm, the "ellipse" that satisfies S ≤ L and 1 ≤ L ≤ 300 is considered when calculating the ellipse density. The "ellipse" that does not satisfy this is not considered when calculating the ellipse density (not counted as an "ellipse" when calculating the ellipse density).

[0570] <Measurement of average major axis length>

[0571] The average value of the major axes of the ellipses observed in the measurement of the ellipsoid density was calculated.

[0572] <Measurement of ellipse perfection>

[0573] First, as an optical interference type non-contact surface shape measuring machine, "VertScan2.0 (model R5500GML)" manufactured by Ryoka Systems Inc. was used. In WAVE mode, a 530 white filter and a 1×BODY lens barrel were applied, and a ×10 objective lens was used to obtain surface shape data of 470.92 μm × 353.16 μm in each field of view. This operation was performed at 10 locations at intervals of 1 cm from the center in the flow direction and width direction of the target sample (polypropylene film) along the flow direction.

[0574] Next, the obtained data was subjected to noise removal processing using a median filter (3×3), and then subjected to Gaussian filter processing with a cutoff value of 30 μm to remove the curvature component.

[0575] From the projection images of the surface shape data of the 10 locations obtained as described above, three projection images of craters consisting of pairs of circular arcs are extracted. It should be noted that the projection images are projection images obtained by projecting the part of the fine concavoconvexity with a height of 0.02 μm or more onto the film surface.

[0576] When extracting the crater projection images, three crater projection images were extracted in which no overlap of arcs based on different β-type spherulites was confirmed. The three extraction methods extracted ellipses that were quartiles (the first quartile, the second quartile (i.e., the median), and the third quartile) in the area of ​​the ellipse based on visual observation.

[0577] Next, for the three extracted crater projection images, the total length Lt of the paired arcs and the total circumference Lc of the imaginary circular ring containing the paired arcs are measured respectively to obtain the ratio (Lt / Lc). Then, the total 30 values ​​of the aforementioned ratio obtained are averaged to obtain the average value α of the ratio (Lt / Lc).

[0578] The virtual ring was determined and Lt and Lc were measured using the plug-in function "Edge Curve Length" of the analysis software "VS-Viewer" of the optical interference non-contact surface shape measuring instrument VertScan 2.0. The specific steps are as follows.

[0579] (1) First, Figure 3 As shown in (a), let the two points on the arc 30a and the arc 30b that are farthest from each other be P 1 , P 2 , make sure P is connected 1 With P 2 The straight line (hereinafter referred to as the straight line (P 1 -P 2 )).

[0580] (2) Then, Figure 3 As shown in (b), from the straight line (P 1 -P 2 ) on one side ( Figure 3 In the middle, the ratio of the straight line (P 1 -P 2 ) is also on the upper side. From the shapes (position data) of the arcs 30a and 30b of the portion ) of FIG. 3 , a straight line (P 1 -P 2 ) becomes the major axis of the ellipse (E 0 ). Then, the ellipse (E 0 ) of the curve (ellipse (E 0 ) is a part of the circumference of the circle, and the part between the arc 30a and the arc 30b on the above side is supplemented as the supplementary line 40a. It should be noted that, Figure 3 In the example, the ellipse (E 0 ) in the figure, except for the portion corresponding to the supplementary line 40a, the illustration is omitted.

[0581] (3) Then, Figure 3 As shown in (c), from the straight line (P 1 -P 2 ) on the other side ( Figure 3 In the middle, the ratio of the straight line (P 1 -P 2 ) is still on the lower side. From the shapes (position data) of the arcs 30a and 30b of the portion ) of FIG. 3 , a straight line (P1 -P 2 ) becomes the major axis of the ellipse (E 1 ). Then, the ellipse (E 1 ) of the curve (ellipse (E 1 ) is a part of the circumference of the arc 30a, and the part between the arc 30a and the arc 30b on the other side is supplemented as a supplementary line 40b. It should be noted that Figure 3 In the example, the ellipse (E 1 ) in the figure, except for the portion corresponding to the supplementary line 40b, the illustration is omitted.

[0582] (4) The following is obtained by connecting the supplementary lines 40a, 40b determined in this way with the arcs 30a, 30b: Figure 3 The ring shown in (c) is a hypothetical ring.

[0583] (5) Then, a height profile of the fine asperities 20 is drawn, which indicates the height of the fine asperities 20 at each position relative to the circumference of the imaginary ring (the distance when a certain point of the circumference is used as a reference). From the height profile, Lt and Lc in the crater projection image G corresponding to the portion with a height of 0.02 μm or more are read.

[0584] It should be noted that when the least square method was implemented, 30 (n=30) pieces of position data were used.

[0585] <Measurement of dielectric breakdown strength of polypropylene film (voltage resistance evaluation)>

[0586] The dielectric breakdown voltage of the polypropylene film was measured 12 times at 100°C and 125°C using a DC power supply in accordance with JIS C2330 (2001) 7.4.11.2B method (flat electrode method). DC The dielectric breakdown strength ES (V DC The results are shown in Table 3.

[0587] It should be noted that in Comparative Examples 1 and 4, the dielectric breakdown strength at 120°C is lower than 485V. DC / μm, it can be seen that the withstand voltage is poor.

[0588] <Evaluation of blocking of metal deposition roller>

[0589] For the biaxially stretched polypropylene film, aluminum evaporation is performed with a evaporation resistance of 15Ω / □ as a T process excess evaporation pattern to obtain a metal layer integrated polypropylene film. Pattern evaporation is performed according to a vacuum evaporation method based on a line method, and heavy edge evaporation is performed according to a vacuum evaporation method based on a crucible method. The film used in the evaporation is 620mm wide, and the length of the film after evaporation is 50000m. A blade is placed in the center of each process excess part of the 620mm wide metal layer integrated polypropylene film, and the slitting process is performed at a slitting speed of 350m / min to make it into a small roll with a width of 30mm and a length of 10000m. At this time, in the metal evaporation roll unwinding section, the situation where the wrinkles in the flow direction caused by the adhesion between the evaporation surface and the non-evaporation surface are not observed is evaluated as AA, the situation where a small amount of stripes are observed that are not wrinkles is evaluated as A, the situation where the wrinkles in the flow direction are observed at the end of the width direction is evaluated as B, and the situation where the wrinkles in the flow direction are also observed in the central part of the width direction is evaluated as C. The results are shown in Table 3.

[0590] <Determination of ash content>

[0591] The polypropylene films of Examples and Comparative Examples were measured as follows.

[0592] About 200 g of the sample was weighed, transferred to a platinum dish, and ash was burned at 800° C. for 40 minutes. The ash content (ppm) was measured from the obtained ash residue. The results are shown in Table 3.

[0593] <Evaluation of processability in slitting process>

[0594] The metallized coil with a width of 620 mm was slit at a slitting speed of 350 m / min to a width of 30 mm and a length of 10,000 m, and then divided into 20 in the width direction. As a result, the case where the end surface misalignment (misalignment length when the film meanders to the left and right during winding and the end surface of the small coil becomes irregular) of all the obtained 20 small coils was evaluated as A, the case where the end surface misalignment of all the 20 small coils was within 1.0% of the slitting width and did not fall into the above-mentioned A evaluation was evaluated as B, the case where the end surface misalignment of all the 20 small coils was within 2.0% of the slitting width and did not fall into the above-mentioned A evaluation or B evaluation was evaluated as C, and the case where the end surface misalignment of the 20 small coils exceeded 2.0% of the slitting width and there was one or more was evaluated as D. The results are shown in Table 3.

[0595] <Evaluation of component winding processability>

[0596] For the small coil obtained by the slitting processability evaluation, a winding reel with a left process allowance and a winding reel with a right process allowance are used, and two sheets are overlapped and wound in a manner that the vapor-deposited portion in the width direction extends further than the process allowance portion (component winding processing). The winding is performed as follows: using an automatic coiler 3KAW-N2 manufactured by Kaito Seisakusho Co., Ltd., 1360 strands are performed at a coiling tension of 200g. At this time, the start of winding to the end of winding is visually observed, and wrinkles and misalignments are recorded as unqualified. The ratio of the number of unqualified products to the total number of manufactured products is expressed as a percentage as an indicator of processability (hereinafter referred to as the component winding rate). The higher the component winding rate, the better. 95% or more is evaluated as good "○", and less than 95% is evaluated as poor "×". The results are shown in Table 3.

[0597] [Table 3]

[0598]

[0599] <Capacitor production and electrostatic capacitance>

[0600] Using the polypropylene film obtained in the example, a capacitor is made as described below. For the polypropylene film, aluminum is evaporated into a T process excess evaporation pattern with an evaporation resistance of 15Ω / □, thereby obtaining a metal layer integrated polypropylene film containing a metal film on one side of the polypropylene film. After slitting into 60mm width, two metal layer integrated polypropylene films are bonded together and wound with 1076 strands using an automatic winder 3KAW-N2 manufactured by Kaito Seisakusho Co., Ltd. at a winding tension of 250g. For the wound components, heat treatment is performed at 120°C for 15 hours while applying pressure, and then zinc metal is sprayed on the end surface of the component to obtain a flat capacitor. The lead is soldered to the end surface of the flat capacitor and then sealed with epoxy resin. The electrostatic capacitance of the manufactured capacitors is 75μF (±5μF).

[0601] The first embodiment of the present invention has been described above.

[0602] <Second embodiment of the present invention>

[0603] Next, a second embodiment of the present invention will be described.

[0604] Using the polypropylene resins described in the section "First Example of the Invention" (resin A1, resin A2, resin B1, resin B2, resin C1, resin X1, resin X2), polypropylene films of the following examples and comparative examples were prepared and their physical properties were evaluated.

[0605] <Production of polypropylene film>

[0606] (Example 9)

[0607] Resin A1, resin B1 and resin C1 are dry-blended. The mixing ratio is set to (resin A1): (resin B1): (resin C1) = 64:33:3 in terms of mass ratio. After that, the dry-blended resin is melted at a resin temperature of 250°C, extruded using a T-die, wound on a metal drum maintained at a surface temperature of 95°C and solidified to prepare a cast sheet. At this time, the cast sheet is prepared while pushing the molten extruded resin composition to the metal drum with an air knife. The obtained unstretched cast sheet is passed through rollers maintained at a temperature of 130°C and provided with a speed difference, stretched to 4.5 times in the flow direction, and immediately cooled to room temperature. Then, the stretched film is introduced into a tenter, stretched to 8 times in the width direction at a temperature of 158°C, relaxed, heat-set, and wound up, and aged in an atmosphere of about 40°C to obtain the polypropylene film of Example 9.

[0608] (Example 10, Comparative Example 9 to Comparative Example 14)

[0609] Except that the mixing ratio when dry-blending the raw material resins was changed as shown in Table 4, the polypropylene films of Example 10 and Comparative Examples 9 to 14 were obtained in the same manner as in Example 9.

[0610] However, in Comparative Example 14, a smooth cast sheet could not be produced due to melt fracture during extrusion molding. Therefore, the cast sheet was broken when stretched.

[0611] (Example 11 to Example 13, Comparative Example 15, Comparative Example 16)

[0612] Except that the mixing ratio when dry-blending the raw material resins was changed as shown in Table 4, the polypropylene films of Examples 11 to 13 and Comparative Examples 15 and 16 were obtained in the same manner as in Example 9.

[0613] [Table 4]

[0614]

[0615] <Measurement of thickness of polypropylene film>

[0616] The thickness of the polypropylene films of Examples and Comparative Examples was measured by the same method as described in the section "Example 1 of the present invention".

[0617] <Svk value of the first surface (Svk A ), the Spk value of the first side (Spk A ), the Svk value of the second surface (Svk B ), the Spk value of the second side (Spk B ), the Sq value of the first side (Sq A), the Sq value of the second side (Sq B ), the Sa value of the first side (Sa A ), the Sa value of the second side (Sa B ), the Sk value of the first surface (Sk A ) and the Sk value of the second surface (Sk B ) determination>

[0618] The Svk value (Svk A ), the Spk value of the first side (Spk A ), the Svk value of the second surface (Svk B ), the Spk value of the second side (Spk B ), the Sq value of the first side (Sq A ), the Sq value of the second side (Sq B ), the Sa value of the first side (Sa A ), the Sa value of the second side (Sa B ), the Sk value of the first surface (Sk A ) and the Sk value of the second surface (Sk B ). The results are shown in Table 5. It should be noted that in Table 5, the ratio Spk B / Spk A , than Svk B / Svk A , than Sq B / Sq A , than Sa B / Sa A , than Sk B / Sk A The value of .

[0619] <Measurement of elliptic density>

[0620] The ellipticity of the first surface (surface A) and the second surface (surface B) of the polypropylene films of Examples and Comparative Examples was measured by the same method as described in the section "First Example of the Invention".

[0621] <Measurement of average major axis length>

[0622] The average value of the major axes of the ellipses observed in the measurement of the ellipsoid density was calculated.

[0623] <Measurement of ellipse perfection>

[0624] The ellipticity of the polypropylene films of Examples and Comparative Examples was obtained by the same method as that described in the section "Example 1 of the present invention".

[0625] <Measurement of dielectric breakdown strength of polypropylene film (voltage resistance evaluation)>

[0626] The dielectric breakdown strength ES (V DC The results are shown in Table 5.

[0627] It should be noted that in Comparative Examples 9 and 12, the dielectric breakdown strength at 120°C is lower than 485V. DC / μm, the withstand voltage difference can be seen.

[0628] <Evaluation of blocking of metal deposition roller>

[0629] The blocking evaluation of the metal deposition roll was performed by the same method as the method described in the section of “Example 1 of the present invention”.

[0630] <Determination of ash content>

[0631] The ash content of the polypropylene film was measured by the same method as that described in the section "First Example of the Invention".

[0632] <Evaluation of processability in slitting process>

[0633] The slitting process processability was evaluated by the same method as that described in the section "Example 1 of the present invention".

[0634] <Evaluation of component winding processability>

[0635] The element winding processability was evaluated by the same method as that described in the section "Example 1 of the present invention".

[0636] [Table 5]

[0637]

[0638] <Capacitor production and electrostatic capacitance>

[0639] Using the polypropylene film obtained in the example, a capacitor is made as described below. For the polypropylene film, aluminum is evaporated into a T process excess evaporation pattern with an evaporation resistance of 15Ω / □, thereby obtaining a metal layer integrated polypropylene film containing a metal film on one side of the polypropylene film. After slitting into 60mm width, two metal layer integrated polypropylene films are bonded together and wound with 1076 strands using an automatic winder 3KAW-N2 manufactured by Kaito Seisakusho Co., Ltd. at a winding tension of 250g. For the wound components, heat treatment is performed at 120°C for 15 hours while applying pressure, and then zinc metal is sprayed on the end surface of the component to obtain a flat capacitor. The lead is soldered to the end surface of the flat capacitor and then sealed with epoxy resin. The electrostatic capacitance of the manufactured capacitors is 75μF (±5μF).

[0640] The second embodiment of the present invention has been described above.

[0641] <Third Embodiment of the Invention>

[0642] Next, a third embodiment of the present invention will be described.

[0643] Using the polypropylene resins described in the section "First Example of the Invention" (resin A1, resin A2, resin B1, resin B2, resin C1, resin X1, resin X2), polypropylene films of the following examples and comparative examples were prepared and their physical properties were evaluated.

[0644] <Production of polypropylene film>

[0645] (Example 14)

[0646] Resin A1, resin B1 and resin C1 are dry-blended. The mixing ratio is set to (resin A1): (resin B1): (resin C1) = 63:34:3 in terms of mass ratio. After that, the dry-blended resin is melted at a resin temperature of 250°C, extruded using a T-die, wound on a metal drum maintained at a surface temperature of 95°C and solidified to prepare a cast sheet. At this time, the cast sheet is prepared while pushing the molten extruded resin composition to the metal drum with an air knife. The obtained unstretched cast sheet is passed between rollers maintained at a temperature of 130°C and having a speed difference, stretched to 4.5 times in the flow direction, and immediately cooled to room temperature. Then, the stretched film is introduced into a tenter, stretched to 8 times in the width direction at a temperature of 158°C, relaxed, heat-set, and wound up, and aged in an atmosphere of about 40°C to obtain the polypropylene film of Example 14.

[0647] (Example 15, Comparative Examples 17 to 22)

[0648] Except that the mixing ratio when dry-blending the raw material resins was changed as shown in Table 6, the polypropylene films of Example 15 and Comparative Examples 17 to 22 were obtained in the same manner as in Example 14.

[0649] However, in Comparative Example 22, a smooth cast sheet could not be produced due to melt fracture during extrusion molding. Therefore, the cast sheet was broken when stretched.

[0650] (Example 16 to Example 18, Comparative Example 23, Comparative Example 24)

[0651] Except that the mixing ratio when dry-blending the raw material resins was changed as shown in Table 6, the polypropylene films of Examples 16 to 18 and Comparative Examples 23 and 24 were obtained in the same manner as in Example 14.

[0652] [Table 6]

[0653]

[0654] <Measurement of thickness of polypropylene film>

[0655] The thickness of the polypropylene films of Examples and Comparative Examples was measured by the same method as described in the section "Example 1 of the present invention".

[0656] <Measurement of elliptic density>

[0657] The ellipticity of the first surface (surface A) and the second surface (surface B) of the polypropylene films of Examples and Comparative Examples was measured by the same method as described in the section "First Example of the Invention".

[0658] <Measurement of average major axis length>

[0659] The average value of the major axes of the ellipses observed in the measurement of the ellipsoid density was calculated.

[0660] <Measurement of ellipse perfection>

[0661] The ellipticity of the polypropylene films of Examples and Comparative Examples was obtained by the same method as that described in the section "Example 1 of the present invention".

[0662] <Sq value of the first surface (Sq A ), the Sq value of the second side (Sq B ), the Sa value of the first side (Sa A ), the Sa value of the second side (Sa B ), the Sk value of the first surface (Sk A ) and the Sk value of the second surface (Sk B) determination>

[0663] The Sq value (Sq A ), the Sq value of the second side (Sq B ), the Sa value of the first side (Sa A ), the Sa value of the second side (Sa B ), the Sk value of the first surface (Sk A ) and the Sk value of the second surface (Sk B The results are shown in Table 7. It should be noted that in Table 7, the ratio Sq B / Sq A , than Sa B / Sa A , than Sk B / Sk A The value of .

[0664] <Measurement of dielectric breakdown strength of polypropylene film (voltage resistance evaluation)>

[0665] The dielectric breakdown strength ES (V DC The results are shown in Table 7.

[0666] It should be noted that in Comparative Examples 17 and 20, the dielectric breakdown strength at 120°C is lower than 485V. DC / μm, it can be seen that the withstand voltage is poor.

[0667] <Evaluation of blocking of metal deposition roller>

[0668] The blocking evaluation of the metal deposition roll was performed by the same method as the method described in the section of “Example 1 of the present invention”. The results are shown in Table 7.

[0669] <Determination of ash content>

[0670] The ash content of the polypropylene film was measured by the same method as that described in the section "First Example of the Invention".

[0671] <Evaluation of processability in slitting process>

[0672] The slitting process processability was evaluated by the same method as that described in the section "Example 1 of the present invention".

[0673] <Evaluation of component winding processability>

[0674] The element winding processability was evaluated by the same method as that described in the section "Example 1 of the present invention".

[0675] [Table 7]

[0676]

[0677] <Capacitor production and electrostatic capacitance>

[0678] Using the polypropylene film obtained in the example, a capacitor is made as described below. For the polypropylene film, aluminum is evaporated into a T process excess evaporation pattern with an evaporation resistance of 15Ω / □, thereby obtaining a metal layer integrated polypropylene film containing a metal film on one side of the polypropylene film. After slitting into 60mm width, two metal layer integrated polypropylene films are bonded together and wound with 1076 strands using an automatic winder 3KAW-N2 manufactured by Kaito Seisakusho Co., Ltd. at a winding tension of 250g. For the wound components, heat treatment is performed at 120°C for 15 hours while applying pressure, and then zinc metal is sprayed on the end surface of the component to obtain a flat capacitor. The lead is soldered to the end surface of the flat capacitor and then sealed with epoxy resin. The electrostatic capacitance of the manufactured capacitors is 75μF (±5μF).

[0679] The third embodiment of the present invention has been described above.

Claims

1. A polypropylene film, characterized in that has a first side and a second side, and Contains polypropylene resin as the main component, The ellipse density D of the first surface A 85~120 pieces / mm 2 , The ellipse density D of the second surface B 1~12 pieces / mm 2 , The polypropylene resin comprises: A linear polypropylene resin A, wherein in a molecular weight differential distribution curve, the difference obtained by subtracting a differential distribution value when Log(M)=6.0 from a differential distribution value when the logarithmic molecular weight Log(M)=4.5 is 8.0% or more; A linear polypropylene resin B, wherein in a molecular weight differential distribution curve, the difference obtained by subtracting a differential distribution value when Log(M)=6.0 from a differential distribution value when the logarithmic molecular weight Log(M)=4.5 is less than 8.0%; and Long-chain branched polypropylene resin C, which is obtained by polymerization using a metallocene catalyst, The ellipse density is the total count per unit area of ​​the following X and the following Y observed by a digital oscilloscope, wherein when the length of one axis is L μm and the length of the other axis is S μm, an “ellipse” that satisfies S ≤ L and 1 μm ≤ L ≤ 300 μm is considered when calculating the ellipse density. X: A circular or elliptical shape formed by two arc-shaped protrusions in pairs. Y: An elliptical shape formed by interpolating and connecting two pairs of circular arc shapes.

2. The polypropylene film according to claim 1, characterized in that For capacitors.

3. The polypropylene film according to claim 1, characterized in that Made by biaxial stretching.

4. The polypropylene film according to claim 1, characterized in that The ellipse density D constituting the first surface A The average major axis length L of the ellipse A 20~80μm, The ellipse density D constituting the second surface B The average major axis length L of the ellipse B 30~100μm.

5. A metal layer integrated polypropylene film, characterized in that: have: The polypropylene film according to any one of claims 1 to 4; and A metal layer laminated on one or both sides of the polypropylene film.

6. A film capacitor, characterized in that: The invention has a structure in which the metal layer integrated polypropylene film according to claim 5 is wound, or has a structure in which a plurality of metal layer integrated polypropylene films according to claim 5 are laminated.

7. A film roll, characterized in that: The polypropylene film according to any one of claims 1 to 4 is wound into a roll.

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