Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/10—Homopolymers or copolymers of propene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
  • B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B15/08—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B15/08—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
  • B32B15/085—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin comprising polyolefins
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/18—Manufacture of films or sheets
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L101/00—Compositions of unspecified macromolecular compounds
  • C08L101/02—Compositions of unspecified macromolecular compounds characterised by the presence of specified groups, e.g. terminal or pendant functional groups
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G4/00—Fixed capacitors; Processes of their manufacture
  • H01G4/002—Details
  • H01G4/018—Dielectrics
  • H01G4/06—Solid dielectrics
  • H01G4/14—Organic dielectrics
  • H01G4/18—Organic dielectrics of synthetic material, e.g. derivatives of cellulose
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G4/00—Fixed capacitors; Processes of their manufacture
  • H01G4/32—Wound capacitors
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
  • B32B2307/514—Oriented
  • B32B2307/518—Oriented bi-axially
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
  • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
  • C08J2323/10—Homopolymers or copolymers of propene
  • C08J2323/12—Polypropene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2423/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
  • C08J2423/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
  • C08J2423/10—Homopolymers or copolymers of propene
  • C08J2423/12—Polypropene

Definitions

• the present invention relates to a stretched film, a metal laminated film and a film capacitor using the same, and in particular to a stretched film with excellent heat resistance suitable for use in a capacitor.
• Stretched films made primarily of polypropylene are moisture-proof, rigid, heat-resistant, and are used for a variety of industrial applications, including packaging.
• applications have expanded, there has been a demand for higher performance, and there are particularly high hopes for suppressing the loss of rigidity at high temperatures.
• stretched films whose main component is polypropylene are used for film capacitor applications due to their excellent electrical properties.
• Film capacitors made of stretched films whose main component is polypropylene are used in electronic devices, electrical equipment, etc., for example as high-voltage capacitors; various switching power supplies; filter capacitors for converters, inverters, etc., and smoothing capacitors. Film capacitors are used, for example, in inverters and converters that control drive motors in automobiles such as electric vehicles and hybrid vehicles, for which demand has been increasing in recent years.
• Film capacitors are increasingly being used in high-temperature environments.
• devices inverters, converters, etc.
• highly heat-resistant semiconductors such as silicon carbide semiconductors
• capacitors used in these devices are also required to have high heat resistance, for example, of 120°C or higher, and preferably 130°C or higher.
• Capacitors that use conventional polypropylene film are said to have an upper limit of operating temperature of approximately 110°C, and it is extremely difficult to stably maintain electrical insulation in high-temperature environments that exceed this limit.
• Patent Document 2 a film using a polypropylene resin and a resin having an alicyclic structure in the main chain of the polymer obtained by polymerizing a cyclic olefin monomer has been disclosed.
• Resin films whose main component is polypropylene tend to show a decline in physical properties such as a decrease in rigidity and electrical insulation when the temperature at which they are used increases.
• a resin film whose main component is polypropylene is stretched in at least one direction, and preferably in two directions, to form a stretched film, which improves rigidity and electrical insulation and maintains these properties even in high-temperature ranges where the usage temperature exceeds 110°C.
• the usage temperature reaches 120°C or higher, or even 130°C or higher, it is difficult for even a stretched film to maintain its rigidity and electrical insulation.
• Patent Document 1 contains a hydrogenated block copolymer, which gives it excellent water vapor impermeability, but since it is an unstretched film, its rigidity and electrical insulation properties cannot be said to be high. Furthermore, when stretching mixed resins, pores are often formed within the layers during stretching, which reduces rigidity and electrical insulation properties. Therefore, special consideration is required to find stretching conditions that improve the physical properties while suppressing the formation of pores, but Patent Document 1 does not disclose any knowledge regarding stretching conditions.
• the film described in Patent Document 2 is a stretched film made of a mixed resin that has excellent electrical properties at high temperatures, but the mixed cyclic olefin resin is a resin that has an alicyclic structure in the polymer main chain, making the resin rigid.
• the mixed cyclic olefin resin is a resin that has an alicyclic structure in the polymer main chain, making the resin rigid.
• a thin thickness is required, for example 10 ⁇ m or less, and preferably 5 ⁇ m or less, but in this thickness range, the film becomes more susceptible to breakage.
• the film formation speed and deposition speed are increased to reduce costs, there is a production problem in that the film becomes even more susceptible to breakage.
• the present invention therefore aims to provide a stretched film that is inhibited from decreasing in physical properties such as rigidity and electrical insulation even in high-temperature environments exceeding 110°C (particularly in high-temperature environments of 120°C or higher), and that also has excellent stretchability and passability through post-processing steps.
• the present invention relates to the following stretched film, a metal laminated film and a film capacitor using the same.
• a stretched film having at least layer A (1) The A layer contains, in 100% by mass, 55% by mass or more and 99% by mass or less of a polypropylene-based resin and 1% by mass or more and 45% by mass or less of a polymer having an alicyclic structure in a side chain, (2) The layer A is stretched in at least one direction.
• a stretched film characterized by: 2. The stretched film according to item 1, wherein the layer A contains, based on 100% by mass, 55% by mass to 97% by mass of a polypropylene resin and 3% by mass to 45% by mass of a polymer having an alicyclic structure in a side chain. 3.
• the stretched film according to item 1 or 2 wherein the polymer has a glass transition temperature of 100° C. or higher and 180° C. or lower. 4.
• a metal laminated film comprising the stretched film according to any one of items 1 to 5 above and a metal layer laminated on one or both sides of the film.
• a film capacitor comprising the stretched film according to any one of items 1 to 5.
• a film capacitor comprising the metal laminated film according to item 6.
• the present invention makes it possible to provide a stretched film that is suppressed from decreasing in physical properties such as rigidity and electrical insulation even in high-temperature environments exceeding 110°C, and that also has excellent stretchability and passability through post-processing steps.
• the present invention provides a stretched film having at least layer A, (1)
• the A layer contains, in 100% by mass, 55% by mass or more and 99% by mass or less of a polypropylene resin and 1% by mass or more and 45% by mass or less of a polymer having an alicyclic structure in a side chain, (2)
• the layer A is stretched in at least one direction.
• the present invention relates to a stretched film characterized by the above-mentioned. This will be described below.
• Polypropylene Resin Layer A of the stretched film of the present invention contains 55% by mass to 99% by mass of a polypropylene resin, with the mass of layer A being 100% by mass.
• the polypropylene-based resins include, for example, propylene homopolymers such as isotactic polypropylene and syndiotactic polypropylene; copolymers of propylene and other olefins (such as ethylene and 1-butene) (the copolymer may be a random copolymer or a block copolymer having at least two polymer blocks); long-chain branched polypropylene; and polypropylene-based resins produced from plant-derived raw materials.
• propylene homopolymers such as isotactic polypropylene and syndiotactic polypropylene
• copolymers of propylene and other olefins such as ethylene and 1-butene
• the copolymer may be a random copolymer or a block copolymer having at least two polymer blocks
• long-chain branched polypropylene and polypropylene-based resins produced from plant-derived raw materials.
• the propylene content in the copolymer is 50% by mass or more, preferably 80% by mass or more, and more preferably 90% by mass or more, with the mass of the polypropylene resin being 100% by mass.
• the polypropylene resin does not include polypropylene resins having an alicyclic structure in the side chain.
• the polypropylene resin contained in layer A may be one type or two or more types.
• the content of polypropylene resin contained in layer A may be 55% by mass or more and 99% by mass or less, but is preferably 55% by mass or more and 97% by mass or less, more preferably 60% by mass or more and 90% by mass or less, and even more preferably 65% by mass or more and 85% by mass or less.
• the rigidity, electrical insulation, and stretchability of the stretched film of the present invention are improved.
• the stretched film of the present invention is a multilayer film having other layers in addition to layer A (such as a skin layer, which will be described later)
• the effect of improving stretchability includes the case where the entire multilayer film is stretched (the same applies below).
• the melt mass flow rate (MFR) of the polypropylene resin contained in layer A is preferably 0.5 g/10 min to 6 g/10 min, more preferably 1 g/10 min to 5 g/10 min, and even more preferably 1.5 g/10 min to 4 g/10 min, when measured at 230°C and 2.16 kg weight. In this case, appropriate resin fluidity is obtained when the film is stretched, improving stretchability.
• the melting point of the polypropylene resin contained in layer A is preferably 155°C or higher. In this case, electrical insulation and extensibility at high temperatures are improved.
• the melting point is more preferably 160°C or higher and 180°C or lower, and even more preferably 163°C or higher and 170°C or lower.
• the polypropylene resin contained in layer A preferably has a mesopentad fraction of 95 mol% or more and 99.9 mol% or less. If it is 95 mol% or more, the rigidity and electrical insulation of the stretched film of the present invention are likely to be improved, and if it is 99.9 mol% or less, the stretchability is likely to be improved.
• the mesopentad fraction of the polypropylene resin is more preferably 96 mol% or more and 99.5 mol% or less, even more preferably 97 mol% or more and 99.2 mol% or less, and particularly preferably 98 mol% or more and 99 mol% or less.
• the heptane insoluble content (HI) of the polypropylene resin contained in Layer A is preferably 94% by mass or more and 99.9% by mass or less. If it is 94% by mass or more, the rigidity and electrical insulation of the stretched film are likely to be improved, and if it is 99.9% by mass or less, the stretchability is likely to be improved.
• the heptane insoluble content of the polypropylene resin is more preferably 96% by mass or more and 99.5% by mass or less, even more preferably 97% by mass or more and 99.2% by mass or less, and particularly preferably 98% by mass or more and 99% by mass or less.
• the number average molecular weight (Mn) of the polypropylene resin contained in Layer A is preferably 30,000 or more and 70,000 or less, and more preferably 35,000 or more and 65,000 or less.
• Mn number average molecular weight
• the weight average molecular weight (Mw) of the polypropylene resin contained in Layer A is preferably 250,000 or more and 500,000 or less, and more preferably 300,000 or more and 450,000 or less.
• Mw weight average molecular weight
• the molecular weight distribution (Mw/Mn) of the polypropylene resin contained in Layer A calculated as the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferably 3 to 12, more preferably 5 to 10, and even more preferably 6 to 9.5.
• Layer A contains a polypropylene resin with such a molecular weight distribution (Mw/Mn)
• the rigidity, electrical insulation, and stretchability of the stretched film of the present invention are likely to be improved.
• the z-average molecular weight (Mz) of the polypropylene resin contained in Layer A is preferably 700,000 or more and 3,000,000 or less, and more preferably 1,000,000 or more and 2,500,000 or less.
• Mz z-average molecular weight
• the molecular weight distribution (Mz/Mw) of the polypropylene resin contained in Layer A calculated as the ratio of the z-average molecular weight (Mz) to the weight-average molecular weight (Mw), is preferably 2 to 7, more preferably 2.5 to 6, and even more preferably 3 to 5.
• Layer A contains a polypropylene resin with such a molecular weight distribution (Mz/Mw)
• the rigidity, electrical insulation, and stretchability of the stretched film of the present invention are likely to be improved.
• Polypropylene-based resins can be produced using conventional methods. Examples of polymerization methods include gas phase polymerization, bulk polymerization, and slurry polymerization.
• the polymerization may be a single-stage polymerization using one polymerization reactor, or a multi-stage polymerization using two or more polymerization reactors.
• the polymerization may be carried out by adding hydrogen or a comonomer as a molecular weight regulator to the reactor.
• the polymerization catalyst conventional Ziegler-Natta catalysts or metallocene catalysts can be used, and the polymerization catalyst may contain a cocatalyst component or a donor.
• the mesopentad fraction, melt mass flow rate, molecular weight, and molecular weight distribution of the polypropylene-based resin can be controlled by appropriately adjusting the polymerization catalyst and other polymerization conditions.
• the layer A of the stretched film of the present invention contains 1% by mass to 45% by mass of a polymer having an alicyclic structure in a side chain, with the mass of the layer A being 100%.
• the polymer having an alicyclic structure in a side chain contained in the layer A may be one type or two or more types.
• the content of the polymer having an alicyclic structure in the side chain contained in Layer A may be 1% by mass or more and 45% by mass or less, but is preferably 3% by mass or more and 45% by mass or less, more preferably 10% by mass or more and 40% by mass or less, and even more preferably 15% by mass or more and 35% by mass or less. In this case, the rigidity, electrical insulation, and stretchability of the stretched film of the present invention are improved.
• the alicyclic structure includes one or more saturated and/or unsaturated carbon ring structures that do not have aromaticity. There may be two or more carbon ring structures.
• the carbon ring structure may have a branched aliphatic hydrocarbon structure. The carbon ring structure is bonded directly or via a hydrocarbon chain to the hydrocarbon chain of the polymer backbone.
• Examples of the carbon ring structure include monocyclic structures such as cycloalkane structures such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, cycloundecane, and cyclododecane, and cycloalkene structures such as cyclopropene, cyclobutene, cyclopropene, cyclohexene, cycloheptene, and cyclooctene.
• cycloalkane structures such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, cycloundecane, and cyclododecane
• cycloalkene structures
• bicyclic structures include bicyclic alkane structures such as bicycloundecane, and bicyclic alkene structures such as norbornene and norbornadiene, which can be suitably used.
• a carbon ring structure having 4 to 8 carbon atoms is preferable, a monocyclic carbon ring structure having 4 to 8 carbon atoms is more preferable, a carbon ring structure of a monocyclic cycloalkane structure having 4 to 8 carbon atoms is even more preferable, and a cyclohexane structure is particularly preferable.
• the polymer main chain is mainly composed of aliphatic hydrocarbons.
• the polymer main chain may contain cyclic hydrocarbon structures and/or aromatic hydrocarbon structures as structural units, but it is preferable that these are not contained.
• the aliphatic hydrocarbons in the polymer main chain may have branches of aliphatic hydrocarbon structures and/or aromatic hydrocarbon structures.
• the polymer having an alicyclic structure in the side chain may be a homopolymer having a structure having an alicyclic structure in the side chain as a constituent unit.
• it may be polyvinylcycloolefin obtained by homopolymerizing vinylcycloolefin.
• polyvinylcycloolefin examples include polyvinylcyclopropane, polyvinylcyclobutane, polyvinylcyclopentane, polyvinylcyclohexane, polyvinylcycloheptane, polyvinylcyclooctane, polyvinylcyclononane, polyvinylcyclodecane, polyvinylcycloundecane, and polyvinylcyclododecane.
• homopolymers they tend to have high rigidity and electrical insulation in high temperature environments, which is preferable.
• polyvinylcyclopentane, polyvinylcyclohexane, and polyvinylcycloheptane are preferable, and polyvinylcyclohexane is most preferable.
• the method for producing the polymer having an alicyclic structure in a side chain is not particularly limited, and the polymer can be produced using a known method such as a radical polymerization method, an ionic polymerization method (anionic polymerization method, coordination anionic polymerization method, etc.), for example, a polymerization method such as bulk polymerization, solution polymerization, or suspension polymerization.
• a radical polymerization method such as a radical polymerization method, an ionic polymerization method (anionic polymerization method, coordination anionic polymerization method, etc.)
• a polymerization method such as bulk polymerization, solution polymerization, or suspension polymerization.
• the polymer having an alicyclic structure in the side chain according to the present invention can be produced by carrying out a polymerization reaction using a known initiator such as an alkyl lithium compound or a dilithium compound to sequentially polymerize a monomer having an alicyclic structure (such as vinylcycloolefin); or a method in which a monomer having an alicyclic structure is sequentially polymerized and then a coupling agent is added to couple the monomers.
• a known initiator such as an alkyl lithium compound or a dilithium compound
• a monomer having an alicyclic structure such as vinylcycloolefin
• a coupling agent is added to couple the monomers.
• a polymer having an alicyclic structure in the side chain can be produced by polymerizing a monomer having an aromatic ring structure (e.g., styrene) by a known method, followed by a hydrogenation reaction.
• the hydrogenation reaction can be carried out, for example, by the method described in the method for producing a hydrogenated block copolymer, which will be described later.
• the hydrogenation rate to the aromatic ring structure is preferably 50 mol% or more, more preferably 80 mol% or more, even more preferably 85 mol% or more, particularly preferably 90 mol% or more, and even more particularly preferably 95 mol% or more.
• the hydrogenation rate may be 100 mol%.
• the polymer having an alicyclic structure in the side chain may be a copolymer having a structural unit having an alicyclic structure in the side chain and one or more other structural units.
• the copolymer may be a random copolymer or a block copolymer having at least two polymer blocks. From the viewpoint of extensibility, copolymers are preferred, and block copolymers are more preferred.
• Other structural units include, for example, ethylene, propylene, butene, pentene, hexene, heptene, octene, etc., and may or may not have a side chain. In addition, it may contain both structural units with side chains and structural units without side chains. Examples of structural units with side chains include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, etc., as structural units.
• the other structural units may be unsaturated hydrocarbons, but from the viewpoint of electrical insulation, saturated hydrocarbons are preferred.
• the polymer having an alicyclic structure in the side chain contains propylene as another structural unit
• the content of propylene in the polymer is less than 50% by mass, preferably 20% by mass or less, and more preferably 10% by mass or less, taking the mass of the polymer as 100% by mass.
• a polymer having an alicyclic structure in the side chain can be obtained, for example, by polymerizing monomers having the respective structural units by a known method. It can also be obtained by hydrogenating a polymer having an aromatic ring structure in the side chain. Hydrogenating a polymer having an aromatic ring structure in the side chain is preferable because it is easy to obtain a polymer having an alicyclic structure in the side chain industrially at low cost.
• the polymer having an aromatic ring structure in the side chain may be a homopolymer or a copolymer.
• a block copolymer having at least a vinyl aromatic polymer block and a conjugated diene polymer block is preferred.
• a hydrogenated block copolymer having at least a hydrogenated vinyl aromatic polymer block and a hydrogenated conjugated diene polymer block is obtained.
• a hydrogenated block copolymer that has at least a hydrogenated vinyl aromatic polymer block and a hydrogenated conjugated diene polymer block.
• the hydrogenated vinyl aromatic polymer block contains a constituent unit derived from a vinyl aromatic compound and hydrogenated therefrom.
• the hydrogenated vinyl aromatic polymer block contains 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass of the constituent unit derived from the vinyl aromatic compound.
• vinyl aromatic compounds examples include styrene, ⁇ -methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4-(phenylbutyl)styrene, vinyltoluene, 1-vinylnaphthalene, 2-vinylnaphthalene, etc.
• the vinyl aromatic compound is preferably selected from styrene and ⁇ -methylstyrene, more preferably styrene.
• the hydrogenated vinyl aromatic polymer block may be composed of only one of the above vinyl aromatic compounds, or may be composed of two or more of them.
• the hydrogenated vinyl aromatic polymer block may contain other structural units in addition to structural units derived from vinyl aromatic compounds.
• other structural units include structural units derived from isoprene, butadiene, 2,3-dimethyl-butadiene, 1,3-pentadiene, 1,3-hexadiene, etc.
• the content of the hydrogenated vinyl aromatic polymer block is preferably 50% by mass or more and less than 100% by mass, based on 100% by mass of the total of the hydrogenated vinyl aromatic polymer block and the hydrogenated conjugated diene polymer block. By making it 50% by mass or more, the rigidity and electrical insulation at high temperatures tend to be high. It is more preferably 60% by mass or more, even more preferably 70% by mass or more, and particularly preferably 80% by mass or more.
• the hydrogenated conjugated diene polymer block contains structural units derived from a conjugated diene and hydrogenated thereof.
• the hydrogenated conjugated diene polymer block contains 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass of structural units derived from a conjugated diene.
• Conjugated dienes include, for example, butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-butadiene, 1,3-pentadiene, 1,3-hexadiene, etc.
• the conjugated diene is preferably selected from butadiene and isoprene, and more preferably butadiene.
• the hydrogenated conjugated diene polymer block may contain structural units derived from a conjugated diene having no side chain.
• conjugated dienes having no side chains include butadiene, 1,3-pentadiene, and 1,3-hexadiene.
• the preferred conjugated diene having no side chains is butadiene.
• the bond form of the conjugated diene i.e., the microstructure
• the bond form in the case of butadiene, can be 1,2-bond or 1,4-bond.
• the bond form in the case of isoprene, can be 1,2-bond, 3,4-bond or 1,4-bond. Only one type of these bond forms may be present, or two or more types may be present. When two or more types of bond forms are present, the ratio of the bond forms is not particularly limited.
• the hydrogenated conjugated diene polymer block may contain other structural units in addition to the structural units derived from the conjugated diene.
• the other structural units include structural units derived from styrene, ⁇ -methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4-(phenylbutyl)styrene, vinyltoluene, 1-vinylnaphthalene, 2-vinylnaphthalene, etc.
• the content of the hydrogenated conjugated diene polymer block is preferably more than 0% by mass (e.g., 1% by mass or more) and 50% by mass or less, based on 100% by mass of the total of the hydrogenated vinyl aromatic polymer block and the hydrogenated conjugated diene polymer block.
• 50% by mass or less it is preferable because the rigidity and electrical insulation at high temperatures tend to be high. More preferably, it is 40% by mass or less, even more preferably 30% by mass or less, and particularly preferably 20% by mass or less.
• the hydrogenation rate of the aromatic ring of the hydrogenated vinyl aromatic polymer block is preferably 50 mol% or more, more preferably 80 mol% or more, even more preferably 85 mol% or more, particularly preferably 90 mol% or more, and even more particularly preferably 95 mol% or more.
• the hydrogenation rate may be 100 mol%.
• the hydrogenation rate of the carbon-carbon double bonds derived from the conjugated diene of the hydrogenated conjugated diene polymer block is preferably 90 mol% or more, more preferably 95 mol% or more.
• the hydrogenation rate may be 100 mol%.
• the bonding mode of the polymer blocks in the hydrogenated block copolymer may be any one of linear, branched and radial, and may be a combination of these.
• the bonding patterns include diblock copolymers (X-Y), triblock copolymers (X-Y-X), tetrablock copolymers (X-Y-X-Y), pentablock copolymers (X-Y-X-Y-X, or Y-X-Y-X-Y), etc.
• the bonding pattern is preferably a diblock copolymer, triblock copolymer, or tetrablock copolymer.
• hydrogenated block copolymers include hydrogenated block copolymers of styrene-isoprene diblock copolymer (SI), styrene-butadiene diblock copolymer (SB), styrene-isoprene-styrene triblock copolymer (SIS), styrene-butadiene/isoprene-styrene triblock copolymer (SB/IS), styrene-butadiene-styrene triblock copolymer (SBS), styrene-ethylene-butylene-styrene copolymer (SEBS), styrene-ethylene-propylene-styrene copolymer (SEPS), styrene-ethylene-ethylene-propylene-styrene copolymer (SEEPS), styrene-butylene-butadiene-styrene copolymer (
• the method for producing the hydrogenated block copolymer is not particularly limited, and any known method such as anionic polymerization can be used.
• the hydrogenated block copolymer according to the present invention can be produced by carrying out a polymerization reaction using a method of sequentially polymerizing a vinyl aromatic compound and a conjugated diene using an alkyllithium compound as an initiator; a method of sequentially polymerizing a vinyl aromatic compound and a conjugated diene using an alkyllithium compound as an initiator and then coupling by adding a coupling agent; or a method of sequentially polymerizing a conjugated diene and then a vinyl aromatic compound using a dilithium compound as an initiator, followed by a hydrogenation reaction.
• alkyllithium compounds include methyllithium, ethyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, and pentyllithium.
• Coupling agents include divinylbenzene; polyfunctional epoxy compounds such as epoxidized 1,2-polybutadiene, epoxidized soybean oil, and 1,3-bis(N,N-glycidylaminomethyl)cyclohexane; halogen compounds such as dimethyldichlorosilane, dimethyldibromosilane, trichlorosilane, methyltrichlorosilane, tetrachlorosilane, and tetrachlorotin; ester compounds such as methyl benzoate, ethyl benzoate, phenyl benzoate, diethyl oxalate, diethyl malonate, diethyl adipate, dioctyl adipate, dimethyl phthalate, diethyl phthalate, dimethyl isophthalate, and dimethyl terephthalate; carbonate compounds such as dimethyl carbonate, diethyl carbonate, and diphenyl carbonate; and
• Dilithium compounds include naphthalene dilithium and dilithiohexylbenzene.
• the polymerization reaction is preferably carried out in the presence of a solvent.
• a solvent there are no particular limitations on the solvent as long as it is inactive to the initiator and does not adversely affect the reaction, and examples of the solvent include saturated aliphatic hydrocarbons such as hexane, cyclohexane, heptane, octane, and decane; and aromatic hydrocarbons such as toluene, benzene, and xylene.
• the temperature of the polymerization reaction is preferably 0 to 100°C, more preferably 30 to 90°C, even more preferably 40 to 80°C, and particularly preferably 50 to 80°C, from the viewpoint of microstructure control.
• the time of the polymerization reaction is preferably 0.5 to 50 hours from the viewpoint of microstructure control.
• a Lewis base may be used as a co-catalyst during the polymerization reaction.
• Lewis bases include ethers such as dimethyl ether, diethyl ether, and tetrahydrofuran; glycol ethers such as ethylene glycol dimethyl ether and diethylene glycol dimethyl ether; and amines such as triethylamine, N,N,N',N'-tetramethylethylenediamine, and N-methylmorpholine. These Lewis bases may be used alone or in combination of two or more.
• the hydrogenation reaction may be carried out immediately after the polymerization reaction, or may be carried out after isolating the block copolymer after the polymerization reaction.
• the polymerization reaction liquid obtained after the polymerization reaction can be poured into a poor solvent for the block copolymer, such as methanol, to solidify the block copolymer, or the polymerization reaction liquid can be poured into hot water together with steam to remove the solvent by azeotropy (steam stripping), and then the block copolymer can be isolated by drying.
• a poor solvent for the block copolymer such as methanol
• the hydrogenation reaction of the block copolymer can be carried out, for example, in the presence of a hydrogenation catalyst at a reaction temperature of 20 to 200°C and a hydrogen pressure of 0.1 to 20 MPa for 0.1 to 100 hours.
• Hydrogenation catalysts include Raney nickel; heterogeneous catalysts in which metals such as platinum (Pt), palladium (Pd), ruthenium (Ru), rhodium (Rh), and nickel (Ni) are supported on a carrier such as carbon, alumina, or diatomaceous earth; Ziegler catalysts consisting of a combination of a transition metal compound (nickel octylate, nickel naphthenate, nickel acetylacetonate, cobalt octylate, cobalt naphthenate, cobalt acetylacetonate, etc.) with an organoaluminum compound such as triethylaluminum or triisobutylaluminum, or an organolithium compound; and metallocene catalysts consisting of a combination of a bis(cyclopentadienyl) compound of a transition metal such as titanium, zirconium, or hafnium with an organometallic compound such as lithium, sodium, potassium
• the hydrogenated block copolymer can be isolated by pouring the hydrogenation reaction liquid into a poor solvent for the hydrogenated block copolymer, such as methanol, to solidify it, or by pouring the hydrogenation reaction liquid into hot water together with steam to remove the solvent by azeotropy (steam stripping), and then drying it.
• a poor solvent for the hydrogenated block copolymer such as methanol
• the glass transition temperature (Tg) of the polymer having an alicyclic structure in the side chain contained in Layer A of the present invention is preferably 100°C or higher and 180°C or lower. By setting the glass transition temperature to 100°C or higher, the rigidity and electrical insulation at high temperatures are likely to be increased, and by setting it to 180°C or lower, the stretchability can be improved.
• the glass transition temperature is more preferably 120°C or higher and 165°C or lower, more preferably 130°C or higher and 160°C or lower, and particularly preferably 140°C or higher and 155°C or lower.
• the Vicat softening point (1 kg, 50°C/hr) of the polymer having an alicyclic structure in the side chain contained in layer A is preferably 100°C or higher and 170°C or lower.
• the Vicat softening point is more preferably 120°C or higher and 165°C or lower, more preferably 130°C or higher and 160°C or lower, and particularly preferably 140°C or higher and 155°C or lower.
• the glass transition temperature (Tg) and Vicat softening point of the polymer having an alicyclic structure in the side chain contained in Layer A can be adjusted by the type of structural unit having the aforementioned alicyclic structure in the side chain, or the type and ratio of one or more other structural units.
• the weight average molecular weight (Mw) of the polymer having an alicyclic structure in the side chain contained in Layer A is not particularly limited, but is preferably 50,000 or more and 400,000 or less.
• Mw weight average molecular weight
• the melt mass flow rate (MFR) of the polymer having an alicyclic structure in the side chain contained in layer A is preferably 1 g/10 min to 40 g/10 min when measured at 260°C and 2.16 kg weight, more preferably 2 g/10 min to 20 g/10 min, and even more preferably 3 g/10 min to 15 g/10 min. In this case, appropriate resin fluidity is obtained when the film is stretched, and stretchability is easily improved.
• the polymer having an alicyclic structure in the side chain contained in layer A may be produced by the method described above, or a commercially available product may be used.
• a commercially available product is ViviOn (registered trademark) (manufactured by USI Corporation).
• the amount of the other resins added is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, with the mass of layer A being 100%.
• the other resins there are no particular limitations on the other resins, and conventionally known resins suitable for stretched film applications can be used appropriately in the present invention.
• Examples include polyolefin resins such as polyethylene, poly(1-butene), polyisobutene, poly(1-pentene), and poly(4-methyl-1-pentene) and copolymer resins thereof, and copolymers of ⁇ -olefins such as ethylene-propylene copolymers, propylene-butene copolymers, ethylene-butene copolymers, and ethylene-(4-methyl-1-pentene) copolymers.
• Other examples include polystyrene resins, elastomers, polyvinyl resins, polyester resins, polyurethane resins, nylon resins, and copolymers thereof.
• the propylene content is less than 50% by mass (e.g., 40% by mass or less), preferably 20% by mass or less, and more preferably 10% by mass or less, taking the mass of the other resin as 100% by mass.
• Layer A can further contain inorganic particles, organic particles, etc., either alone or in combination of two or more types. By containing particles, the friction coefficient and surface roughness can be adjusted when the film is stretched, and a film can be wound up with a good shape and no wrinkles. Furthermore, when the stretched film is used for capacitor applications, its electrical properties (self-healing properties) can be improved.
• the inorganic particles are not particularly limited, and examples thereof include particles of metal oxides such as titanium oxide, zinc oxide, aluminum oxide, and magnesium oxide; and silicon compounds such as silica, and are preferably used.
• other examples of inorganic particles include particles of light calcium carbonate, heavy calcium carbonate, kaolin, calcined kaolin, talc, calcium sulfate, barium sulfate, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, alumina, colloidal alumina, boehmite, pseudo-boehmite, aluminum hydroxide, magnesium carbonate, magnesium hydroxide, zeolite, and smectite.
• organic particles include resin particles made of crosslinkable resin, silicone resin particles, etc.
• the particle content is, for example, 0.1% by mass to 2.0% by mass, preferably 0.2% by mass to 1.5% by mass, and more preferably 0.3% by mass to 1.2% by mass, taking the mass of layer A as 100% by mass.
• Layer A may further contain an antioxidant.
• Antioxidants are primarily used for the following two purposes. One purpose is to suppress thermal and oxidative degradation of the resin in the film-forming extruder and/or melt kneader, and the other purpose is to suppress the deterioration of physical properties such as strength due to deterioration during long-term use of the stretched film. An example of the latter is to contribute to suppressing deterioration during long-term use and maintaining the electrical properties of the capacitor when used in a capacitor.
• antioxidant that primarily contributes to the former purpose is also called a "primary agent,” and an antioxidant that primarily contributes to the latter purpose is also called a “secondary agent.”
• primary agent an antioxidant that primarily contributes to the former purpose
• secondary agent an antioxidant that primarily contributes to the latter purpose.
• Two or more types of antioxidants may be used for these two purposes, or one type of antioxidant may be used for both purposes.
• BHT 2,6-di-tertiary-butyl-para-cresol
• Secondary agents include, for example, hindered phenol-based antioxidants having a carbonyl group.
• hindered phenol-based antioxidants examples include triethylene glycol-bis[3-(3-tertiary-butyl-5-methyl-4-hydroxyphenyl)propionate] (trade name: Irganox 245), 1,6-hexanediol-bis[3-(3,5-di-tertiary-butyl-4-hydroxyphenyl)propionate] (trade name: Irganox 259), pentaerythritol tetrakis[3-(3,5-di-tertiary-butyl-4-hydroxyphenyl)propionate] (trade name: Irganox 1010), 2,2-thiazole-bis[3-(3,5-di-tertiary-butyl-4-hydroxyphenyl)propionate] (trade name: Irganox 1010), 2,2-thiazole-bis[3-(3,5
• Examples include N,N'-hexamethylenebis(3,5-di-tertiary-butyl-4-hydroxyphenyl)propionate (trade name: Irganox 1035), octadecyl-3-(3,5-di-tertiary-butyl-4-hydroxyphenyl)propionate (trade name: Irganox 1076), and N,N'-hexamethylenebis(3,5-di-tertiary-butyl-4-hydroxy-hydrocinnamamide) (trade name: Irganox 1098), but pentaerythritol tetrakis[3-(3,5-di-tertiary-butyl-4-hydroxyphenyl)propionate], which has excellent heat resistance, is particularly preferred.
• Irganox registered trademark
• BASF Japan Ltd. the trade names: Irganox (registered trademark) are all manufactured by BASF Japan Ltd.)
• the total content is preferably 1000 ppm by mass to 7000 ppm by mass, and more preferably 2000 ppm by mass to 6000 ppm by mass, based on the mass of Layer A being 100%, from the viewpoint of appropriate effect.
• the hindered phenol-based antioxidant is partially oxidized and decomposed during the extrusion process during the production of the stretched film, and the remaining amount when the film is made into a stretched film is generally 60 to 80% by mass of the aforementioned content.
• Layer A may further contain additives.
• additives include nucleating agents, chlorine absorbents, lubricants, plasticizers, flame retardants, colorants, etc.
• the content of the additives in layer A may be, for example, 0% by mass to 10% by mass, 0% by mass to 5% by mass, 0% by mass to 1% by mass, 0% by mass to 0.5% by mass, or 0% by mass to 0.1% by mass. The practical lower limit is about 0.01% by mass.
• the thickness of the A layer of the present invention is not particularly limited.
• the preferred thickness depends on the application, but for example, for packaging applications and separator applications, a thickness of 5 ⁇ m to 80 ⁇ m, or 10 ⁇ m to 50 ⁇ m is preferably used.
• a thinner thickness is preferable from the viewpoint of reducing the volume of the capacitor and increasing the electrostatic capacitance. From this viewpoint, the thickness is preferably 10 ⁇ m or less, more preferably 9 ⁇ m or less, even more preferably 8 ⁇ m or less, even more preferably 6 ⁇ m or less, particularly preferably 5 ⁇ m or less, especially more preferably 4 ⁇ m or less, and especially preferably 3 ⁇ m or less.
• the thickness after stretching is, for example, 1 ⁇ m or more, preferably 1.5 ⁇ m or more, more preferably 1.8 ⁇ m or more, even more preferably 2 ⁇ m or more, and even more preferably 2.2 ⁇ m or more.
• the stretched film of the present invention is a stretched film having an A layer containing 55% by mass or more and 99% by mass or less of a polypropylene-based resin and 1% by mass or more and 45% by mass or less of a polymer having an alicyclic structure in a side chain, where the mass of the A layer is 100% by mass, and the A layer is stretched in at least one direction.
• the stretched film of the present invention may be a single-layer stretched film consisting of layer A, or may be a multilayer film obtained by laminating multiple layers and/or films using a conventionally known lamination method, such as a coextrusion method, a lamination method, a heat sealing method, a coating method, etc., either alone or in combination.
• the lamination may be performed before or after stretching layer A.
• the multilayer film can have a three-layer structure of layer b/layer a/layer b consisting of a surface layer (skin layer: layer b) and a core layer (layer a), a three-layer structure of layer b/layer a/layer c in which one surface layer is an additional layer (layer c), a four-layer structure of layer b/layer a/layer a/layer c in which there are two core layers, a four-layer structure of layer b/layer a/layer a'/layer c in which one core layer is the other core layer (layer a'), a layer b/layer d/layer a/layer d/layer b in which an intermediate layer is also placed, etc.
• it may be a so-called super multilayer film including a two or more layer structure in which two or more layers of layer a are laminated, or a laminate structure in which ten or more layers of layer a are laminated.
• Each layer to be laminated may be made of a different resin, or may be made of the same resin.
• Layer A of the present invention can be used as any of layers a, a', b, c, d, etc.
• a surface layer when used as a surface layer, it has excellent stretchability, and when used as a core layer, it tends to have excellent rigidity and insulation properties at high temperatures.
• the thickness ratio of layer A to the stretched film of the present invention is preferably 50% or more, more preferably 60% or more, even more preferably 70% or more, and particularly preferably 80% or more, relative to 100% of the stretched film thickness, in order to facilitate the manifestation of the effects of the present invention.
• a preferred surface layer to be laminated is a layer containing a polypropylene resin as a main component and a pigment.
• the polypropylene resin and pigment can be the same as those for layer A.
• the preferred layer structure depends on the application. For example, in packaging applications and separator applications, two or more layers are preferred from the viewpoint of functional separation between the core layer and the skin layer. In capacitor applications, a single layer is preferred from the viewpoint of reducing the thickness, and two or more layers are preferred from the viewpoint of electrical insulation.
• coextrusion methods include the pre-die lamination method, in which the molten resins are brought into contact in a feed block before the die, the in-die lamination method, in which the resins are brought into contact along a path inside the die, and the out-of-die lamination method, in which the resins are discharged from multiple concentric lips and brought into contact.
• the in-die lamination method a multi-layer die such as a three-layer multi-manifold die can be used.
• the thickness of the stretched film of the present invention is not particularly limited.
• the preferred thickness depends on the application, but for example, for packaging applications and separator applications, a thickness of 5 ⁇ m to 80 ⁇ m, or 10 ⁇ m to 50 ⁇ m is preferably used.
• a thinner thickness is preferable from the viewpoint of reducing the volume of the capacitor and increasing the electrostatic capacitance. From this viewpoint, the thickness is preferably 10 ⁇ m or less, more preferably 9 ⁇ m or less, even more preferably 8 ⁇ m or less, even more preferably 6 ⁇ m or less, particularly preferably 5 ⁇ m or less, especially more preferably 4 ⁇ m or less, and especially preferably 3 ⁇ m or less.
• the thickness after stretching is, for example, 1 ⁇ m or more, preferably 1.5 ⁇ m or more, more preferably 1.8 ⁇ m or more, even more preferably 2 ⁇ m or more, and even more preferably 2.2 ⁇ m or more.
• the stretched film of the present invention has high dielectric breakdown strength at high temperatures.
• the dielectric breakdown strength is measured in environments of 120°C and 135°C according to the method described in the Examples below.
• the dielectric breakdown strength of the stretched film of the present invention in an environment of 120° C. is preferably 450 V DC / ⁇ m or more, more preferably 470 V DC / ⁇ m or more, even more preferably 490 V DC / ⁇ m or more, particularly preferably 500 V DC / ⁇ m or more, and even more particularly preferably 510 V DC / ⁇ m or more.
• the upper limit of the dielectric breakdown strength at each of the above temperatures is not particularly limited, and is, for example, 700 V DC / ⁇ m or less, 650 V DC / ⁇ m or less.
• the dielectric breakdown strength of the film of the present invention in an environment of 135° C. is preferably 420 V DC / ⁇ m or more, more preferably 440 V DC / ⁇ m or more, even more preferably 460 V DC / ⁇ m or more, particularly preferably 480 V DC / ⁇ m or more, and even more particularly preferably 490 V DC / ⁇ m or more.
• the upper limit of the dielectric breakdown strength at each of the above temperatures is not particularly limited, and is, for example, 650 V DC / ⁇ m or less, 600 V DC / ⁇ m or less.
• the stretched film of the present invention is preferable because the change in dielectric breakdown strength due to temperature rise is small.
• the dielectric strength maintenance rate (%) which is the ratio of the dielectric breakdown strength in a 135°C environment to the dielectric breakdown strength in a 120°C environment (dielectric breakdown strength in a 135°C environment/dielectric breakdown strength in a 120°C environment), is preferably 87% or more, more preferably 88% or more, even more preferably 89% or more, and particularly preferably 90% or more. There is no particular upper limit, and it is, for example, 100%, 99%, or 98%. Note that the load related to dielectric breakdown strength is significantly different between a 120°C environment and a 135°C environment.
• a general polypropylene film has a small dielectric strength maintenance rate, which is not preferable because the temperature stability of the electrical properties of a capacitor using the film is reduced.
• the stretched film of the present invention is preferable because the change in dielectric breakdown strength is suppressed from a 120°C environment to a 135°C environment, and the temperature stability of the electrical properties of a capacitor using the film is improved.
• the stiffness of the stretched film of the present invention in a high temperature environment is represented by the elongation rate measured by a thermo-mechanical measuring device (TMA) using the method described in the Examples below. It is preferable that the stiffness of the stretched film changes little when the temperature is raised from room temperature to 130°C, and the elongation rate is preferably 4.5% or less, more preferably 4% or less, even more preferably 3.5% or less, and particularly preferably 3% or less. By setting the elongation rate to 5% or less, the stiffness of the stretched film at high temperatures is maintained at a high level. In addition, the electrical insulation at high temperatures is also excellent, which is preferable because it improves the temperature stability of the electrical properties of the capacitor using it.
• the lower limit of the elongation rate is, for example, 0.2% or more, 0.5% or more, or 1% or more. By setting it to 0.2% or more, the stretchability of the film is easily improved.
• the stretched film of the present invention has high post-processing passability.
• the post-processing step is mainly a deposition step for laminating a metal layer.
• the deposition step passability is measured according to the method in the examples described later.
• the stretched film of the present invention can undergo deposition without film breakage, even at a deposition speed as high as 150 m/min.
• the uses of the stretched film of the present invention are not particularly limited.
• the film of the present invention can be used as a packaging film or separator with excellent heat resistance by taking advantage of its heat resistance.
• the stretched film of the present invention can also be suitably used as a film for capacitors.
• it can be extremely suitably used for capacitors that are used in high-temperature environments of 120°C or more, and that are small and have a high capacity (for example, 5 ⁇ F or more, preferably 10 ⁇ F or more, and more preferably 20 ⁇ F or more).
• the raw material of the stretched film of the present invention (containing at least the above-mentioned polypropylene resin and the above-mentioned polymer having an alicyclic structure in the side chain) is dried before use if it contains a large amount of water.
• the drying conditions are not particularly limited, but are, for example, 70 to 150°C, preferably 80 to 130°C.
• the drying time can be appropriately adjusted depending on the drying temperature, and is, for example, 2 to 30 hours, preferably 3 to 20 hours.
• the raw materials may be fed into the film-forming extruder individually and mixed inside the film-forming extruder, or they may be mixed before being fed into the film-forming extruder and fed into the film-forming extruder as a raw material mixture.
• melt kneading (melt blending) may be used. Melt kneading is preferable because if the resin can be kneaded uniformly, the rigidity, electrical insulation, stretchability, etc. of the stretched film are likely to be improved.
• a melt kneader of a single screw type, twin screw type, or multiple screw type can be used as a method of melt kneading.
• a twin screw type melt kneader is preferably used because it is highly effective in improving the rigidity, electrical insulation, stretchability, etc. of the stretched film.
• a twin screw type either a co-rotating or counter-rotating kneading type can be used, but from the viewpoint of suppressing resin deterioration, a co-rotating type is preferable.
• the ratio of the diameter and length of the screw of the melt kneader (L/D) is preferably 20 or more, more preferably 25 or more, and even more preferably 28 or more.
• L/D 20 By making L/D 20 or more, the resin is well mixed and the rigidity, electrical insulation, and stretchability of the stretched film are improved. There is no upper limit to L/D, but from the viewpoint of suppressing resin deterioration, it is 80 or less, preferably 50 or less.
• the temperature during melt kneading is preferably 200°C to 300°C, more preferably 220°C to 280°C, in order to balance the suppression of resin deterioration and kneadability.
• an inert gas such as nitrogen to suppress resin deterioration.
• the raw materials and/or raw material mixture of the present invention are supplied to a film-forming extruder and extruded.
• extrusion method There are no particular limitations on the extrusion method, and any known extrusion method can be used.
• the solid raw materials or resin composition of the present invention supplied to the film-forming extruder are mixed in a heated molten state by a screw, filtered through a filter, extruded into a film from a die such as a single-layer T-die, and solidified by contact with a cooling roll set at a predetermined surface temperature to obtain the unstretched film of the present invention.
• extruders for film production include single-screw types, twin-screw types, and multi-screw types with three or more screws.
• screw rotation types include, for example, same-direction rotation and counter-direction rotation.
• the melt temperature is preferably 200 to 300°C, preferably 230 to 280°C, and more preferably 240 to 275°C. This allows the resin to be appropriately mixed, and tends to improve the rigidity, electrical insulation, stretchability, etc. of the stretched film. To suppress deterioration during melt extrusion of the resin, it is preferable to purge the extruder with an inert gas such as nitrogen.
• the filtration accuracy of the filter used to filter the molten resin of the present invention is not particularly limited, but is, for example, 2 to 30 ⁇ m, preferably 5 to 25 ⁇ m, and more preferably 10 to 25 ⁇ m.
• the temperature of the die is not particularly limited, but is preferably 200 to 300°C, more preferably 210 to 280°C, more preferably 215 to 270°C, and even more preferably 220 to 260°C.
• the method of contacting the molten resin of the present invention extruded from the die with a cooling roll to solidify it is not particularly limited, and examples include air knife, electrostatic pinning, elastic roll nip, metal roll nip, elastic metal roll nip, etc.
• the surface temperature of the cooling roll is, for example, 30 to 130°C, preferably 35 to 120°C, and more preferably 40 to 110°C.
• the draft ratio when the resin of the present invention extruded from the die and in a molten state is brought into contact with a cooling roll is preferably 1 to 20, more preferably 1.1 to 16, more preferably 1.2 to 10, and even more preferably 1.3 to 8.
• the thickness of the unstretched film of the present invention is not particularly limited, but is, for example, 20 to 300 ⁇ m.
• the method of stretching the unstretched film of the present invention is not particularly limited, and known stretching methods can be used.
• the unstretched film of the present invention is heated with a heating roll and stretched in the longitudinal direction (machine direction, MD) (longitudinal uniaxial roll stretching method); the unstretched film of the present invention is stretched in the transverse direction (width direction, TD) in an oven (generally called a tenter) at a predetermined temperature (transverse uniaxial stretching method); a method of performing transverse uniaxial stretching after longitudinal uniaxial roll stretching (sequential biaxial stretching method); a method of performing transverse uniaxial stretching after longitudinal uniaxial roll stretching and further performing longitudinal uniaxial (roll or tenter method) stretching (multistage sequential biaxial stretching method); a method of performing longitudinal and transverse stretching of the unstretched film of the present invention in a tenter at a predetermined temperature (tenter method sequential biaxial stretching method); a method of simultaneously performing longitudinal and transverse stretching of the unstretched film
• a method for stretching the unstretched film of the present invention a method in which longitudinal uniaxial roll stretching is followed by transverse uniaxial stretching (sequential biaxial stretching method) is preferred, as it provides excellent rigidity, electrical insulation, stretchability, etc. of the stretched film.
• a plurality of heating rolls may be used.
• the stretching point may be one or two or more.
• the temperature (T MD ) of the roll immediately before the stretching point (pre-stretching roll), and when there are two or more stretching points, the surface temperature (T MD ) of the pre-stretching roll at the point where the stretching ratio is maximum is preferably 125°C or more and 175°C or less, more preferably 130°C or more and 170°C or less, even more preferably 135°C or more and 168°C or less, and particularly preferably 140°C or more and 166°C or less.
• the longitudinal stretching ratio (the product of the stretching points when there are two or more stretching points) is preferably 1.5 times or more and 5.0 times or less, more preferably 2.0 times or more and 4.6 times or less, and even more preferably 2.2 times or more and 4.2 times or less.
• the tenter of the present invention is preferably one having three or more temperature zones so that heating, stretching, and the heating treatment, relaxation treatment, cooling treatment, etc. described below can be performed at different temperatures, and more preferably one having five or more temperature zones.
• the oven temperature ( TMD ) during the stretching is preferably 125° C. to 175° C., more preferably 130° C. to 170° C., even more preferably 135° C. to 168° C., and particularly preferably 140° C. to 166° C.
• the longitudinal stretching ratio is preferably 1.5 to 5.0 times, more preferably 2.0 to 4.6 times, and even more preferably 2.2 to 4.2 times.
• the oven temperature ( TTD ) during the stretching is preferably 140° C. to 175° C., more preferably 145° C. to 170° C., even more preferably 150° C. to 168° C., and particularly preferably 155° C. to 166° C.
• the stretching ratio in the transverse direction is preferably 5.0 times to 11.0 times, more preferably 6.0 times to 10.0 times, and even more preferably 7.0 times to 9.5 times.
• T MD and T TD are more preferably adjusted according to the glass transition temperature (Tg) of the polymer having an alicyclic structure in the side chain contained in the layer A of the present invention.
• T MD is preferably Tg-10°C or more and Tg+25°C or less, more preferably Tg-5°C or more and Tg+20°C or less, and even more preferably Tg or more and Tg+16°C or less.
• T TD is preferably Tg or more and Tg+30°C or less, more preferably Tg+5°C or more and Tg+28°C or less, and even more preferably Tg+10°C or more and Tg+25°C or less.
• the total light transmittance of the stretched film of the present invention is preferably 80% or more, more preferably 85% or more, even more preferably 88% or more, and particularly preferably 90% or more. From the viewpoint of the electrical characteristics (safety) of the capacitor, the total light transmittance is preferably 99% or less, more preferably 98% or less, even more preferably 97% or less, and particularly preferably 96% or less.
• the product of the longitudinal stretch ratio and transverse stretch ratio of the stretched film (when performing the relaxation treatment described below, this is calculated using the longitudinal stretch ratio before relaxation and the transverse stretch ratio before relaxation) is preferably 15 to 48 times, more preferably 17 to 42 times, even more preferably 19 to 38 times, particularly preferably 21 to less than 35 times, and even more particularly preferably 22 to 34 times.
• Stretched films with an area ratio of 12% or less, and unstretched films (area ratio of 1%) tend to have a tendency to have reduced rigidity and electrical insulation. Also, if the area ratio at which a film can be stretched without breaking is 12% or less, its stretchability cannot be said to be very good.
• the stretched film of the present invention may be subjected to a relaxation treatment (a treatment for reducing the stretch ratio after stretching, for example, by up to 20% of the stretch ratio), a heating treatment, or a cooling treatment, if necessary.
• a relaxation treatment a treatment for reducing the stretch ratio after stretching, for example, by up to 20% of the stretch ratio
• heating treatment or a cooling treatment
• These treatments may be performed independently or in combination, for example, by performing the relaxation treatment and the heating treatment simultaneously, or by performing the relaxation treatment and the cooling treatment simultaneously.
• the relaxation in the lateral direction is preferably 3% or more and 20% or less, more preferably 5% or more and 16% or less, and even more preferably 6.5% or more and 14% or less, relative to the maximum lateral stretching ratio.
• the heat treatment temperature is preferably 150°C or higher and 180°C or lower, more preferably 155°C or higher and 175°C or lower, and even more preferably 160°C or higher and 172°C or lower.
• the heat treatment time is preferably 1 second or higher and 20 seconds or lower, and more preferably 2 seconds or higher and 15 seconds or lower.
• the stretched film of the present invention may be subjected to corona treatment, static electricity removal treatment, heating treatment, etc.
• corona treatment static electricity removal treatment, heating treatment, etc.
• the heating treatment temperature is preferably 20°C or higher and 80°C or lower, more preferably 25°C or higher and 60°C or lower, and even more preferably 30°C or higher and 55°C or lower.
• the heating treatment time is preferably 3 hours or higher and 50 hours or lower, and more preferably 6 hours or higher and 30 hours or lower.
• the present invention relates to a metal laminated film (sometimes referred to as the "metal laminated film of the present invention” in this specification) having the stretched film of the present invention and a metal layer laminated on one or both sides of the stretched film. This will be described below.
• the stretched film of the present invention can have a metal layer on one or both sides, for example to adjust the permeability of gases such as oxygen and water vapor when used as a packaging film, or as an electrode when used as a capacitor.
• Methods for laminating a metal layer on the surface of the stretched film of the present invention include, for example, vacuum plating such as metal vapor deposition and sputtering, or coating and drying of a metal-containing paste, and pressing of metal foil or metal powder.
• vacuum plating such as metal vapor deposition and sputtering
• the vacuum vapor deposition method and the sputtering method are more preferred, and the vacuum vapor deposition method is even more preferred.
• Examples of vacuum vapor deposition methods include the crucible method and the wire method, but are not particularly limited, and the most suitable method can be selected as appropriate.
• the metal used in the metal layer may be, for example, a single metal such as zinc, lead, silver, chromium, aluminum, copper, or nickel, or a mixture of two or more of these metals or an alloy of these metals. However, taking into consideration the environment, economy, and performance, one or more of zinc and aluminum are preferred.
• the film resistance of the metal layer is preferably about 0.5 to 10 ⁇ / ⁇ from the viewpoint of permeability to gases such as oxygen and water vapor, and about 1 to 60 ⁇ / ⁇ from the viewpoint of the electrical properties of the capacitor. From the viewpoint of the electrical properties of the capacitor, in order to realize the self-healing properties, the film resistance is more preferably 5 ⁇ / ⁇ or more, and even more preferably 10 ⁇ / ⁇ or more, and from the viewpoint of safety as a capacitor, the film resistance is more preferably 50 ⁇ / ⁇ or less, and even more preferably 30 ⁇ / ⁇ or less.
• the film resistance can be measured during deposition, for example, by a non-contact eddy current method or light transmittance method known to those skilled in the art.
• the film resistance of the metal vapor deposition film can be adjusted, for example, by adjusting the output of the evaporation source to adjust the amount of evaporation.
• the film resistance of the heavy edge portion is usually about 1 to 8 ⁇ / ⁇ , and preferably about 1 to 5 ⁇ / ⁇ .
• the thickness of the metal film of the heavy edge portion is not particularly limited, but is preferably 1 to 200 nm.
• fuses As pattern deposition such as a fishnet pattern or T-margin pattern.
• a metal deposition film with a deposition pattern including fuses is formed on at least one side of the stretched film of the present invention, the safety of the resulting capacitor is improved, and it is also effective and preferable in terms of preventing destruction and short circuits of the capacitor.
• the method for forming the fuse and the aforementioned insulating margin can be any known method without any restrictions, such as the tape method in which masking is performed with tape during deposition, or the oil method in which masking is performed by applying oil.
• a protective agent may be applied to the metal laminate film of the present invention for the purposes of physical protection of the metal layer, prevention of moisture absorption, prevention of oxidation, etc.
• the protective agent silicone oil, fluorine oil, etc. can be preferably used.
• the protective agent may be provided as a layer on the metal layer, or may be impregnated into the metal layer.
• the metal laminated film of the present invention can be processed into the capacitor of the present invention described below.
• the metal laminated film of the present invention can also be used for packaging purposes, for example as a barrier film against oxygen and other gases.
• the present invention relates to a film capacitor (sometimes referred to as the "capacitor of the present invention” in this specification) including the stretched film of the present invention or the metal laminated film of the present invention. This will be described below.
• the stretched film of the present invention can be used as a dielectric film for a capacitor by, for example, (i) using the metal laminate film described above, (ii) laminating the stretched film of the present invention without electrodes with a dielectric having metallized surfaces on both sides (the dielectric can be, for example, the stretched film of the present invention or another plastic film), or (iii) laminating the stretched film of the present invention without electrodes with another conductor (for example, a metal foil).
• the dielectric can be, for example, the stretched film of the present invention or another plastic film
• another conductor for example, a metal foil
• a film is wound.
• a pair of two metal laminated films of the present invention are overlapped and wound so that the metal layers of the metal laminated film of the present invention and the stretched film of the present invention are alternately stacked, and further so that the insulating margins are on opposite sides.
• the winding machine used there are no particular restrictions on the winding machine used, and for example, an automatic winding machine 3KAW-N2 type manufactured by Kaito Seisakusho Co., Ltd. can be used.
• the film wrapping process is not limited to the above method, and other methods may be used, for example, a double-sided vapor-deposited stretched film of the present invention (in which case the heavy edges are positioned at the opposite ends of the front and back sides) and a non-vapor-deposited stretched film of the present invention (2 to 3 mm narrower than the double-sided vapor-deposited stretched film of the present invention) may be alternately laminated and wound.
• a double-sided vapor-deposited stretched film of the present invention in which case the heavy edges are positioned at the opposite ends of the front and back sides
• a non-vapor-deposited stretched film of the present invention 2 to 3 mm narrower than the double-sided vapor-deposited stretched film of the present invention
• the resulting wound product is usually pressed after winding. Pressing promotes tightening of the capacitor and element formation.
• the pressure to be applied is 2 to 20 kg/ cm2 , although the optimum value varies depending on the thickness of the stretched film of the present invention.
• metal is sprayed onto both end surfaces of the winding to create metallikon electrodes, creating a capacitor.
• the capacitor is further subjected to a predetermined heat treatment. That is, the present invention includes a step of subjecting the capacitor to a heat treatment (hereinafter, sometimes referred to as "thermal aging").
• the heat treatment temperature is not particularly limited, but is, for example, 80 to 190°C.
• the method of subjecting the capacitor to heat treatment may be appropriately selected from known methods including, for example, a method using a thermostatic bath under a vacuum atmosphere or a method using high-frequency induction heating.
• the time for which the heat treatment is performed is preferably 1 hour or more, and more preferably 5 hours or more, in terms of obtaining mechanical and thermal stability, but is more preferably 20 hours or less in terms of preventing molding defects such as heat wrinkles and molding.
• the effect of thermal aging can be achieved by carrying out heat treatment. Specifically, the gaps between the films constituting the capacitor based on the stretched film of the present invention are reduced, corona discharge is suppressed, and the internal structure of the stretched film of the present invention changes, promoting crystallization. As a result, it is believed that the electrical insulation properties are improved. If the heat treatment temperature is lower than a specified temperature, the above-mentioned effect of thermal aging cannot be fully achieved. On the other hand, if the heat treatment temperature is higher than the specified temperature, thermal decomposition, oxidative deterioration, etc. may occur in the stretched film of the present invention.
• the metallikon electrodes of a capacitor that has been heat aged are usually welded to lead wires or bus bars.
• the capacitor of the present invention using the stretched film of the present invention can be suitably used in high-temperature environments, and can be made to be small and have a high capacity (for example, 5 ⁇ F or more, preferably 10 ⁇ F or more, and more preferably 20 ⁇ F or more). Therefore, the capacitor of the present invention can be used as a high-voltage capacitor used in electronic devices, electrical devices, etc.; various switching power supplies; filter capacitors for converters, inverters, etc., smoothing capacitors, etc. In addition, the capacitor of the present invention can be suitably used as an inverter capacitor, converter capacitor capacitor, etc. that controls the drive motor of electric vehicles, hybrid vehicles, etc., for which demand has increased in recent years.
• Measurement Methods The measurement methods are as follows.
• a high-temperature GPC device with a built-in differential refractometer (RI), HLC-8121GPC-HT model manufactured by Tosoh Corporation was used.
• Three TSKgel GMHHR-H (20) HT columns manufactured by Tosoh Corporation were used in conjunction. Measurements were performed at a column temperature of 140°C, with trichlorobenzene as the eluent flowing at a flow rate of 1.0 ml/min.
• a calibration curve for the molecular weight M was created using standard polystyrene manufactured by Tosoh Corporation, and the measured values were converted to the molecular weight of polypropylene using the Q-factor to obtain the number average molecular weight (Mn), weight average molecular weight (Mw), and z-average molecular weight (Mz).
• Mn number average molecular weight
• Mw weight average molecular weight
• Mz z-average molecular weight
• Heptane insoluble matter (HI) of polypropylene resin A polypropylene resin was press-molded to 10 mm x 35 mm x 0.3 mm to prepare a measurement sample of about 3 g. Next, about 150 mL of heptane was added and Soxhlet extraction was performed for 8 hours. The heptane insoluble matter was calculated from the sample mass before and after extraction.
• melt flow rate (MFR) of each resin in the form of raw resin pellets was measured in accordance with JIS K 7210-1:2014 using a melt indexer manufactured by Toyo Seiki Co., Ltd. Specifically, 4 g of raw material was inserted into a cylinder set at a test temperature (230°C for polypropylene resin, 260°C for polymers having an alicyclic structure in the side chain and polymers having an alicyclic structure in the main chain), and preheated for 3.5 minutes under a load of 2.16 kg. Thereafter, the weight of the raw material resin extruded from the bottom hole in 30 seconds was measured, and the MFR (g/10 min) was obtained. The above measurement was repeated three times, and the average value was taken as the measured MFR.
• the melting peak (the maximum melting peak when multiple melting peaks are shown) defined in 9.1(1) of JIS-K7121 was taken as the melting point, and the midpoint glass transition temperature defined in 9.3(1) of JIS-K7121 was taken as the glass transition temperature.
• the average particle size of the particles was measured as follows. The powder was scattered on a sample stage so that the individual particles did not overlap as much as possible, and at least 100 particles were observed at 10,000 to 30,000 times magnification using an ultra-high resolution field emission scanning electron microscope (FE-SEM, Hitachi High-Technologies Corporation, S-5200) to obtain observation images. The longest diameter of the particles was measured from the observation images using image analysis software, and the measured values were averaged to obtain the average particle size.
• FE-SEM ultra-high resolution field emission scanning electron microscope
• MFR 3.5g/10min (measurement temperature 230°C, weight 2.16kg) Melting point: 164°C Mesopentad fraction: 98.6 mol% Heptane insolubles: 98.1% by mass Number average molecular weight (Mn): 49000 Weight average molecular weight (Mw): 390000 Z average molecular weight (Mz): 1520000 Molecular weight distribution (Mw/Mn): 8.0 Molecular weight distribution (Mz/Mw): 3.9
• A2 Isotactic polypropylene resin manufactured by Prime Polymer Co., Ltd.
• the side chain has a cyclohexane structure (the cyclohexane structure is formed by hydrogenating an aromatic ring structure, and the hydrogenation rate is 99 mol % or more).
• ViviOn registered trademark 1325 manufactured by USI Corporation Glass transition temperature: 128°C MFR: 13g/10min (measurement temperature 260°C, weight 2.16kg)
• the side chain has a cyclohexane structure (the cyclohexane structure is formed by hydrogenating an aromatic ring structure, and the hydrogenation rate is 99 mol % or more).
• Raw material C Polymer C1 having an alicyclic structure in the main chain : TOPAS (registered trademark) COC6013S-04 manufactured by Polyplastics Co., Ltd.
• the molten resin was solidified by contacting it with a mirror-finished metal roll (cooling roll) with a surface temperature of 90°C using an air knife, and then formed into a film to obtain a single-layer unstretched film.
• the thickness of the unstretched film was fine-tuned by changing the extrusion amount and take-up speed so that the thickness after stretching would reach the target value.
• the unstretched film was introduced into a roll-type longitudinal stretching machine, heated sequentially by five preheating rolls, heated by a pre-stretching roll whose surface temperature was adjusted to the temperature (T MD ) listed in Table 1, and uniaxially stretched in the longitudinal direction (MD) at the ratio listed in Table 1.
• the film was then introduced into a tenter, heated in a preheating zone whose furnace temperature was adjusted to the preheating temperature listed in Table 1, and stretched in the transverse direction (TD) at the ratio listed in Table 1 in a stretching zone whose furnace temperature was adjusted to the temperature (T TD ) listed in Table 1.
• the width (transverse direction) was then relaxed by 10% in a heating zone set at 170°C.
• the end of the stretched film coming out of the tenter was slit to a width of 620 mm, and the surface on the side where the air knife was used was corona-treated, and then wound up to obtain a roll of stretched film.
• the extrusion amount and take-up speed were finely adjusted so that the thickness of the film was 2.8 ⁇ m.
• the stretchability of the films was good in all of Examples 1 to 6, Examples 8 to 10, Comparative Example 1, and Comparative Example 4.
• the film of Comparative Example 2 broke when stretched to the ratio described above, and the stretchability could not be said to be good.
• Layer B/layer A/layer B were laminated in the order inside a three-layer multi-die and extruded from the multi-die.
• the three-layer laminated molten resin was solidified by contacting it with a mirror-finished metal roll (cooling roll) with a surface temperature of 90°C using an air knife, and then formed into a film to obtain a three-layer unstretched film.
• the average slit gap t at the die lip outlet of the multi-die was changed so that the draft ratio was 4.0.
• the thickness of the unstretched film was fine-tuned by changing the extrusion amount and take-up speed so that the thickness after stretching would reach the target value.
• the extrusion rate was adjusted so that the thickness ratio of each layer of the unstretched film was layer B:layer A:layer B, 1:1.8:1.
• the unstretched film was introduced into a roll-type longitudinal stretching machine, heated sequentially by five preheating rolls, heated by a pre-stretching roll with a surface temperature adjusted to 150 ° C, and uniaxially stretched in the longitudinal direction (MD) at a magnification of 4.0 times.
• the film was then introduced into a tenter, heated in a preheating zone with an oven temperature adjusted to 170 ° C, and stretched in the transverse direction (TD) at a magnification of 10.0 times in a stretching zone with an oven temperature adjusted to 167 ° C.
• the width (transverse direction) was then relaxed by 10% in a heating zone set to 170 ° C.
• the end of the stretched film coming out of the tenter was slit to a width of 620 mm, and the surface on the side where the air knife was used was corona-treated, and then wound up to obtain a roll of stretched film.
• the extrusion amount and take-up speed were finely adjusted so that the thickness of the film was 2.8 ⁇ m.
• the stretchability of the film of Example 7 was good.
• the molten resin was solidified by contacting it with a mirror-finished metal roll (cooling roll) with a surface temperature of 90°C using an air knife, and then formed into a film to obtain a single-layer unstretched film.
• the average slit gap t at the die lip exit of the T-die was changed so that the draft ratio was 40.
• the extrusion amount and take-up speed were changed to fine-tune the thickness of the unstretched film to 5 ⁇ m.
• the unstretched film was slit at the end to a width of 620 mm, and the side that had been used with the air knife was corona treated before being wound up to obtain a roll of unstretched film. In this way, a roll of unstretched film was obtained as a comparative product in Comparative Example 3.
• the dielectric breakdown strength of the stretched films obtained in the examples and comparative examples at high temperatures was evaluated as follows.
• a measuring device was prepared according to 17.2.2 (plate electrode method) of JIS C2151:2006.
• a conductive rubber (E12S10 manufactured by Seiwa Electric Co., Ltd.) was used as an electrode instead of the elastic body described in 17.2.2 of JIS C2151:2006, and aluminum foil was not wrapped around the electrode.
• the measurement environment was a forced circulation oven set at 120°C or 135°C, and the electrodes and films were used after 30 minutes of temperature adjustment in the oven.
• the voltage was increased at a rate of 100 V/sec starting from 0 V, and the voltage at which the current value exceeded 5 mA was taken as the dielectric breakdown voltage.
• the dielectric breakdown voltage was measured 20 times, and each dielectric breakdown voltage value VDC was divided by the thickness ( ⁇ m) of the stretched film, and the average of 16 points excluding the top 2 and bottom 2 points out of the 20 calculation results was taken as the dielectric breakdown strength ( VDC / ⁇ m).
• the dielectric strength retention rate (%) was calculated as the ratio of the dielectric breakdown strength in a 135°C environment to the dielectric breakdown strength in a 120°C environment obtained by the above measurements (dielectric breakdown strength in a 135°C environment/dielectric breakdown strength in a 120°C environment).
• Measurement device Seiko Instruments Inc. TMA/SS6000 type Measurement probe: Quartz tensile probe Measurement mode: F mode (load control mode) Static load: Depending on the thickness of the stretched film, the ratio is 16.67 mN per 1 ⁇ m of thickness.
• Initial chuck distance 15 mm
• Temperature setting range 25°C to 170°C Heating rate: 10° C./min
• the stretched film may break due to the difference in peelability, the effect of heat from the metal during deposition, etc. Under these conditions, deposition was performed on a length of 5000 m, and the deposition process passability was evaluated according to the following criteria. ⁇ : The stretched film did not break even once (0 breaks). x: The stretched film breaks at least once.
• a stretched film (Examples 1 to 10) having an A layer containing 55% to 99% by mass of polypropylene resin and 1% to 45% by mass of a polymer having an alicyclic structure in the side chain, with the mass of the A layer being 100%, and in which the A layer is stretched in at least one direction, suppresses the decrease in rigidity and electrical insulation even in a high-temperature environment exceeding 110°C, and also has excellent stretchability and passability through post-processing steps.

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