JP2023113106A - Film suitable for capacitor use - Google Patents

Abstract

To provide a film excellent in element winding aptitude capable of obtaining a capacitor excellent in security function operability, and high in insulation breakdown strength under a high temperature.SOLUTION: A film containing a syndiotactic polystyrene-based resin, a polyphenylene ether-based resin, and titanium oxide particles, wherein a content of the syndiotactic polystyrene-based resin in the film is 50 mass% or greater, a content of the polyphenylene ether resin in the film is 10 mass% or greater, and a content of the titanium oxide particles in the film is 0.55 mass% or greater and 3 mass% or less.SELECTED DRAWING: None

Description

The present invention relates to films and the like. In particular, it relates to a film suitable for use in capacitors.

2. Description of the Related Art Conventionally, in electronic equipment, electrical equipment, etc., capacitors using resin films have been used, for example, as high-voltage capacitors, various switching power supplies, filter capacitors for converters and inverters, and smoothing capacitors. Resin film capacitors are also used in inverters and converters that control drive motors for electric vehicles and hybrid vehicles, for which demand has been increasing in recent years.

Capacitors, especially automotive capacitors, are increasingly being used in high-temperature environments. For example, the use of highly heat-resistant semiconductors (silicon carbide semiconductors, etc.) has recently increased in devices that control the drive motors of automobiles (inverters, converters, etc.). Higher heat resistance is also required for capacitors that Therefore, a resin film containing syndiotactic polystyrene is used as one of resin films having high heat resistance (Patent Document 1).

Japanese Patent Application Laid-Open No. 2011-111592

The inventors of the present invention have focused on the importance of safety function operability of a capacitor element in view of the growing need for reliability over a long period of time.

In a capacitor element, pattern deposition is usually used to create a margin where no metal is deposited, and divide it into electrode strips. At that time, by providing a fuse, current concentrates in the fuse when dielectric breakdown occurs in a part of the small electrode, and the metal film scatters. As a result, the small electrode that caused the dielectric breakdown is cut off, and the insulation of the entire device is restored. Therefore, it is important for safety function operability to scatter the metal film with the fuse. As the voltage is increased, dielectric breakdown of the small electrode occurs, but when the safety function operates, the insulation of the entire element is maintained. On the other hand, if the safety function operation does not work, the entire element will be short-circuited and the performance as a capacitor will be lost. From the viewpoint of operability of safety functions, it is said that roughening the surface of the capacitor film is preferable. However, simply roughening the film surface usually lowers the dielectric breakdown strength.

In particular, there is a growing need for thinner films for in-vehicle capacitors (for example, for xEV) due to demands for smaller size and higher efficiency. However, a thin film has a problem that it has a low element winding aptitude, and is likely to cause winding misalignment in the element winding process when manufacturing a capacitor, for example.

Patent Literature 1 discloses a film having high dielectric breakdown voltage and element winding suitability, which contains a syndiotactic polystyrene-based resin and a polyphenylene ether-based resin having excellent heat resistance. However, Patent Literature 1 does not mention security function operability.

Accordingly, the main object of the present invention is to provide a film that can provide a capacitor excellent in safety function operability, has high dielectric breakdown strength at high temperatures, and has good element winding aptitude.

As a result of intensive research by the present inventor, a film containing a syndiotactic polystyrene-based resin, a polyphenylene ether-based resin, and titanium oxide particles, and the syndiotactic polystyrene in the film The content of the polyphenylene ether-based resin in the film is 50% by mass or more, the content of the polyphenylene ether-based resin in the film is 10% by mass or more, and the content of the titanium oxide particles in the film is 0.55 The inventors have found that the above problems can be solved with a film having a content of 3% by mass or more. The present inventor has completed the present invention as a result of further research based on this finding. That is, the present invention includes the following aspects.

Section 1. a film,
The film contains a syndiotactic polystyrene-based resin, a polyphenylene ether-based resin, and titanium oxide particles,
The content of the syndiotactic polystyrene resin in the film is 50% by mass or more,
The content of the polyphenylene ether-based resin in the film is 10% by mass or more, and the content of the titanium oxide particles in the film is 0.55% by mass or more and 3% by mass or less.
film.

Section 2. Item 2. The film according to Item 1, wherein the content of the syndiotactic polystyrene resin in the film is 50% by mass or more and 85% by mass or less.

Item 3. Item 3. The film according to Item 1 or 2, wherein the content of the polyphenylene ether-based resin in the film is 10% by mass or more and 45% by mass or less.

Section 4. Item 4. The film according to any one of Items 1 to 3, which contains a styrene-based thermoplastic elastomer.

Item 5. Item 5. The film according to Item 4, wherein the content of the styrene-based thermoplastic elastomer in the film is 1% by mass or more and 20% by mass or less.

Item 6. Item 6. The film according to Item 4 or 5, wherein the styrenic thermoplastic elastomer is a styrene-ethylene-butylene-styrene block copolymer (SEBS).

Item 7. Item 7. The film according to any one of Items 1 to 6, which contains an antioxidant.

Item 8. Item 8. The film according to Item 7, wherein the content of the antioxidant in the film is 0.01% by mass or more and less than 0.5% by mass.

Item 9. Item 9. The film of Item 7 or 8, wherein the antioxidant comprises a hindered phenol antioxidant and a phosphorus antioxidant.

Item 10. Item 10. The film according to any one of Items 1 to 9, wherein the titanium oxide particles have an average particle size of 0.1 μm or more and 0.25 μm or less.

Item 11. Item 11. The film according to any one of Items 1 to 10, wherein the height Spk of the protruding peaks on at least one surface is 0.05 μm or more and 0.30 μm or less.

Item 12. Item 12. The film according to any one of Items 1 to 11, wherein the film has a heat shrinkage rate of 1% or more and 10% or less in the film forming direction.

Item 13. Item 13. The film according to any one of Items 1 to 12, which is a biaxially stretched film.

Item 14. Item 14. The film according to any one of Items 1 to 13, which is a single layer film.

Item 15. Item 15. The film according to any one of Items 1 to 14, which has a thickness of 10 μm or less.

Item 16. Item 16. The film according to any one of items 1 to 15, which is used for capacitors.

Item 17. Item 17. A metal layer-integrated film comprising the film according to any one of Items 1 to 16 and a metal layer laminated on one side or both sides of the film.

Item 18. A capacitor comprising the film according to any one of Items 1 to 16 or the metal layer-integrated film according to Item 17.

According to the present invention, it is possible to obtain a capacitor excellent in safety function operability, and to provide a film having high dielectric breakdown strength at high temperatures and excellent element winding aptitude. Moreover, the film of this invention has high film-forming stability in one preferable aspect.

As used herein, the expressions "contain" and "include" include the concepts "contain", "include", "consist essentially of" and "consist only of".

The content rate of each component in the film of the present invention is calculated from the content rate and the mixing ratio of the raw materials when the content rate of the component in each raw material used is known. When using a raw material with an unknown component content, each component in the raw material by the method described in "(1-3) Measurement and calculation of the content of each component in the biaxially stretched film" in the example. The content rate is measured, and the content rate of each component in the film of the present invention is calculated from the content rate and the blending ratio of the raw materials. If the content ratio of the raw materials is unknown, the content of each component in the film of the present invention is determined by the method described in "(1-3) Measurement and calculation of the content of each component in the biaxially stretched film" in the Examples. A content rate is calculated.

1. In one aspect of the present invention , there is provided a film containing a syndiotactic polystyrene-based resin, a polyphenylene ether-based resin, and titanium oxide particles, and the syndiotactic polystyrene-based resin in the film. The content of the resin is 50% by mass or more, the content of the polyphenylene ether-based resin in the film is 10% by mass or more, and the content of the titanium oxide particles in the film is 0.55% by mass. % or more and 3% by mass or less (in this specification, it may be referred to as the "film of the present invention"). This will be explained below.

The syndiotactic polystyrene-based resin is not particularly limited as long as it is a polystyrene-based resin having a syndiotactic structure. The syndiotactic structure means that the stereochemical structure is a syndiotactic structure, that is, the phenyl groups and substituted phenyl groups that are side chains are alternately positioned in the opposite direction to the main chain formed from the carbon-carbon bond. It means having a three-dimensional structure that Tacticity is usually quantified by nuclear magnetic resonance spectroscopy ( ¹³ C-NMR spectroscopy) using carbon isotopes, and the abundance ratio of a plurality of consecutive constitutional units, for example, dyads for two, triads for three, In the case of 5, it can be indicated by a pentad or the like.

The syndiotactic polystyrene resin is, for example, a racemic diad and has a syndiotacticity of, for example, 75% or more, preferably 85% or more. The syndiotactic polystyrene resin is, for example, a racemic pentad and has a syndiotacticity of, for example, 30% or more, preferably 50% or more.

Specific examples of syndiotactic polystyrene resins include polystyrene, poly(alkylstyrene), poly(halogenated styrene), poly(halogenated alkylstyrene), poly(alkoxystyrene), and poly(vinyl benzoate). , hydrogenated polymers thereof, mixtures thereof, copolymers containing these as main components, and the like.

Examples of poly(alkylstyrene) include poly(methylstyrene), poly(ethylstyrene), poly(isopropylstyrene), poly(tert-butylstyrene), poly(phenylstyrene), poly(vinylstyrene), poly(vinyl naphthalene) and the like. Examples of poly(halogenated styrene) include poly(chlorostyrene), poly(bromostyrene), poly(fluorostyrene) and the like. Examples of poly(halogenated alkylstyrene) include poly(chloromethylstyrene) and the like. Examples of poly(alkoxystyrene) include poly(methoxystyrene) and poly(ethoxystyrene).

Particularly preferred syndiotactic polystyrene resins among these include polystyrene, poly(p-methylstyrene), poly(m-methylstyrene), poly(p-tert-butylstyrene), poly(p-chlorostyrene), Poly(m-chlorostyrene), poly(p-fluorostyrene), hydrogenated polystyrene and styrene-alkylstyrene copolymers such as copolymers of styrene and p-methylstyrene, and the like.

The molecular weight of the syndiotactic polystyrene resin is not particularly limited. For example, the mass average molecular weight (weight average molecular weight) is, for example, 10,000 to 3,000,000, preferably 50,000 to 1,000,000, more preferably 100,000 to 500,000. The mass average molecular weight is a value measured by gel permeation chromatography at 135° C. using 1,2,4-trichlorobenzene as a solvent.

The melting point of the syndiotactic polystyrene resin is not particularly limited. The melting point is, for example, 200° C. or higher and 320° C. or lower, preferably 220° C. or higher and 280° C. or lower. The melting point is the melting peak temperature measured according to JIS K7121:2012.

The syndiotactic polystyrene resin can be obtained as a commercial product, or can be produced by a known method. Syndiotactic polystyrene-based resins are available, for example, as "Zarec" (142ZE, 300ZC, 130ZC, 90ZC) manufactured by Idemitsu Kosan Co., Ltd., and the like.

The syndiotactic polystyrene resins can be used singly or in combination of two or more.

The content of the syndiotactic polystyrene resin in the film of the present invention is 50% by mass or more. The syndiotactic polystyrene resin is preferably the component with the highest content in the film of the present invention. In one aspect, the content of the syndiotactic polystyrene resin in the film of the present invention is preferably 50% by mass or more from the viewpoint of safety function operability, dielectric breakdown strength, element winding suitability, film formation stability, etc. It is 85 mass % or less, more preferably 55 mass % or more and 83 mass % or less, still more preferably 58 mass % or more and 75 mass % or less, still more preferably 60 mass % or more and 70 mass % or less. In another aspect, the content of the syndiotactic polystyrene resin in the film of the present invention is preferably 50% by mass or more and 70% by mass or less, particularly preferably 50% by mass or more and 60% by mass or less.

The polyphenylene ether-based resin is not particularly limited, and is typically a polymer having a structural unit represented by the following general formula (1). The polyphenylene ether-based resin may consist of one type of repeating structural unit, or may contain two or more types of repeating structural units.

[In the formula, R ¹ , R ² , R ³ and R ⁴ are the same or different, and are a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted An optionally substituted alkynyl group, an optionally substituted aryl group, an optionally substituted aralkyl group, an optionally substituted alkylaralkyl group, or an optionally substituted alkoxy group. ]

The halogen atom is not particularly limited and includes, for example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the like.

Alkyl groups include any of linear, branched, or cyclic (preferably linear or branched, more preferably linear). The number of carbon atoms in the alkyl group (in the case of linear or branched chain) is not particularly limited, and is, for example, 1-8. The number of carbon atoms is preferably 1-4, more preferably 1-3, even more preferably 1-2, and even more preferably 1. The number of carbon atoms in the alkyl group (in the case of cyclic) is not particularly limited, and is, for example, 3-7, preferably 4-6. Specific examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, sec-butyl group, n-pentyl group, neopentyl group, n -hexyl group, 3-methylpentyl group, n-heptyl group, n-octyl group and the like.

Alkenyl groups include both straight-chain and branched (preferably straight-chain). The number of carbon atoms in the alkenyl group is not particularly limited, and is, for example, 2-8. The number of carbon atoms is preferably 2-4. Specific examples of the alkenyl group include vinyl group, allyl group, 1-propenyl group, isopropenyl group, butenyl group, pentenyl group and hexenyl group.

Alkynyl groups include both straight-chain and branched (preferably straight-chain). The number of carbon atoms in the alkenyl group is not particularly limited, and is, for example, 2-8. The number of carbon atoms is preferably 2-4. Specific examples of the alkynyl group include ethynyl group, propynyl group (eg, 1-propynyl group, 2-propynyl group (propargyl group)), butynyl group, pentynyl group, hexynyl group and the like.

The aryl group is not particularly limited, but preferably has 6 to 12 carbon atoms, more preferably 6 to 12 carbon atoms, and even more preferably 6 to 8 carbon atoms. The aryl group can be either monocyclic or polycyclic (eg, bicyclic, tricyclic, etc.), but is preferably monocyclic. Specific examples of the aryl group include phenyl, naphthyl, biphenyl, pentalenyl, indenyl, anthranyl, tetracenyl, pentacenyl, pyrenyl, perylenyl, fluorenyl, and phenanthryl groups. and preferably a phenyl group.

The aralkyl group is not particularly limited, but includes, for example, an aralkyl group in which hydrogen atoms (eg, 1 to 3, preferably 1 hydrogen atom) of the above alkyl group are substituted with the above aryl group. Specific examples of the aralkyl group include benzyl group and phenethyl group.

The alkylaryl group is not particularly limited, and examples thereof include an alkylaryl group in which hydrogen atoms (eg, 1 to 3, preferably 1 hydrogen atom) of the above aryl group are substituted with the above alkyl group. Specific examples of the alkylaryl group include tolyl group and xylyl group.

The alkylaralkyl group is not particularly limited, and for example, an alkylaralkyl group in which hydrogen atoms (eg, 1 to 3, preferably 1 hydrogen atom) on the aromatic ring of the above aralkyl group are substituted with the above alkyl group, and the like. mentioned.

The alkoxy group is not particularly limited, and has a linear or branched (preferably linear) carbon number of 1 to 8, preferably 1 to 4, more preferably 1 to 3, more preferably 1 to 2. and more preferably one alkoxy group. Examples of the alkoxy group include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy and t-butoxy groups.

Examples of substituents of the above-described alkyl group, alkenyl group, alkynyl group, aryl group, aralkyl group, alkylaryl group, alkylaralkyl group, alkoxy group, etc. include halogen atoms and hydroxy groups. The number of substituents is not particularly limited, and is, for example, 0-3, preferably 0-1, more preferably 0.

In a preferred embodiment of the present invention, R ¹ , R ² , R ³ and R ⁴ are the same or different and represent a hydrogen atom, a halogen atom, or an optionally substituted alkyl group (preferably unsubstituted alkyl group). . R ² and R ³ are preferably hydrogen atoms, and R ¹ and R ⁴ are preferably groups other than hydrogen atoms.

Specific examples of polyphenylene ether resins include poly(2,3-dimethyl-6-ethyl-1,4-phenylene ether), poly(2-methyl-6-chloromethyl-1,4-phenylene ether), ter), poly(2-methyl-6-hydroxyethyl-1,4-phenylene ether), poly(2-methyl-6-n-butyl-1,4-phenylene ether), poly(2-ethyl- 6-isopropyl-1,4-phenylene ether), poly(2-ethyl-6-n-propyl-1,4-phenylene ether), poly(2,3,6-trimethyl-1,4-phenylene ether) ter), poly(2-(4'-methylphenyl)-1,4-phenylene ether), poly(2-bromo-6-phenyl-1,4-phenylene ether), poly(2-methyl-6 -phenyl-1,4-phenylene ether), poly(2-phenyl-1,4-phenylene ether), poly(2-chloro-1,4-phenylene ether), poly(2-methyl-1, 4-phenylene ether), poly(2-chloro-6-ethyl-1,4-phenylene ether), poly(2-chloro-6-bromo-1,4-phenylene ether), poly(2,6 -di-n-propyl-1,4-phenylene ether), poly(2-methyl-6-isopropyl-1,4-phenylene ether), poly(2-chloro-6-methyl-1,4-phenylene ether) -ter), poly(2-methyl-6-ethyl-1,4-phenylene ether), poly(2,6-dibromo-1,4-phenylene ether), poly(2,6-dichloro-1, 4-phenylene ether), poly(2,6-diethyl-1,4-phenylene ether), poly(2,6-dimethyl-1,4-phenylene ether) and other homopolymers, and co- Polymers may be mentioned. Moreover, those modified with a modifying agent such as maleic anhydride or fumaric acid are also preferably used. Furthermore, a copolymer obtained by graft copolymerizing or block copolymerizing a vinyl aromatic compound such as styrene with the polyphenylene ether is also used. Among these, poly(2,6-dimethyl-1,4-phenylene ether) is particularly preferred.

The number average molecular weight of the polyphenylene ether-based resin is not particularly limited, but is preferably 10,000 to 100,000, more preferably 15,000 to 50,000, from the viewpoint of extrusion moldability and continuous stretchability. The number average molecular weight is obtained by converting the value of the molecular weight measured by the GPS method into the value of polystyrene.

A polyphenylene ether resin can be obtained as a commercial product, or can be produced by a known method. Examples of polyphenylene ether-based resins include the Iupiace (registered trademark) series (eg, Iupiace (registered trademark) PX100L, PX100F) manufactured by Mitsubishi Engineering-Plastics Corporation, and the product names manufactured by Asahi Kasei Corporation. Zylon (registered trademark) series (for example, Zylon (registered trademark) S201A) and the like can be preferably used.

Polyphenylene ether-based resins can be used singly or in combination of two or more.

The content of the polyphenylene ether-based resin in the film of the present invention is 10% by mass or more. In one aspect, the content is preferably 10% by mass or more and 45% by mass or less, more preferably 12% by mass or more, from the viewpoint of safety function operability, dielectric breakdown strength, element winding suitability, film forming stability, etc. 40 mass % or less, more preferably 14 mass % or more and 35 mass % or less, even more preferably 17 mass % or more and 30 mass % or less, and particularly preferably 17 mass % or more and 25 mass % or less. In another aspect, the content is preferably 17% by mass or more and 32% by mass or less, more preferably 17% by mass or more and 32% by mass or less, more preferably 24% by mass or more and 31% by mass or less, particularly preferably 25% by mass or more and 29% by mass or less.

The titanium oxide particles are not particularly limited, and examples thereof include particles of titanium dioxide, titanium monoxide, titanium sesquioxide, and the like. Titanium oxide particles preferably include titanium dioxide particles.

Titanium oxide particles are preferable because they tend to reduce the dielectric breakdown strength of the film more than other inorganic particles such as calcium carbonate and silica, and organic particles such as silicone particles. Titanium oxide particles are generally active particles having catalytic activity, but the strength of the activity varies depending on the crystal type. In the present invention, rutile-type titanium oxide, which tends not to lower the dielectric breakdown strength of the film, can be most preferably used.

The average particle size of the titanium oxide particles is, for example, 0.05 μm or more and 0.7 μm or less. The average particle diameter is preferably 0.1 μm or more and 0.5 μm or less, more preferably 0.12 μm or more and 0.4 μm or less, still more preferably 0.15 μm or more and 0.35 μm or less, still more preferably 0 0.15 μm or more and 0.25 μm or less.

The average particle size of titanium oxide particles is a value measured as follows. The powder is scattered on the sample stage so that the individual particles do not overlap as much as possible, and an ultra-high resolution field emission scanning electron microscope ((FE-SEM) Hitachi High Technologies S-5200) is used to measure at least 100 Each particle is observed at a magnification of 10,000 to 30,000 to obtain an observed image. The longest diameter is measured from the observed image using image analysis software, and the measured values are averaged to obtain the average particle diameter.

Titanium oxide particles can be used singly or in combination of two or more.

The content of titanium oxide particles in the film of the present invention is 0.55% by mass or more and 3% by mass or less. The content is preferably 0.6% by mass or more and 2.5% by mass or less, more preferably 0.6% by mass or more, from the viewpoint of safety function operability, dielectric breakdown strength, element winding suitability, film forming stability, and the like. It is 7% by mass or more and 2.0% by mass or less, more preferably 0.7% by mass or more and 1.5% by mass or less.

The film of the present invention preferably contains an antioxidant from the viewpoint of safety function operability, dielectric breakdown strength, element winding suitability, and the like.

Examples of antioxidants include hindered phenol-based antioxidants, phosphorus-based antioxidants, amine-based antioxidants, sulfur-based antioxidants, hydrazine-based antioxidants, and the like. Among these, hindered phenol-based antioxidants and phosphorus-based antioxidants are preferred. In a preferred embodiment of the present invention, the antioxidant preferably contains a hindered phenol-based antioxidant and a phosphorus-based antioxidant.

Examples of hindered phenol antioxidants include pentaerythritol tetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 1,3,5-tris(3,5-di -tert-butyl-4-hydroxybenzyl)isocyanurate, 2,4,6-tris(4-hydroxy-3,5-di-tert-butylbenzyl)mesitylene, 2,2'-methylenebis(6-tert-butyl -4-methylphenol), 6,6′-thiobis(2-tert-butyl-4-methylphenol), diethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate and the like. Among them, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox (registered trademark) 1010, manufactured by BASF) is preferred.

The phosphorus-based antioxidant is not particularly limited as long as it is a compound containing elemental phosphorus. Specifically, triphenylphosphite, tris(2,4-t-butylphenyl)phosphite, bis[2,4bis(1,1-dimethylethyl)-6-methylphenyl]ethyl ester phosphorous acid, Bis(2,4-t-butylphenyl)pentaerythritol diphosphite, tetrakis(2,4-di-t-butylphenyl)[1,1biphenyl]-4,4'-diylbisphosphonite, tetra (C12-C15 alkyl)-4,4′-isopropylidene diphenyl diphosphite, 3,9-bis(2,6-t-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3 ,9-diphosphaspiro[5,5undecane], 1,1′-biphenyl-4,4′-diylbis[bis(2,4-di-t-butylphenyl)phosphonous acid] and the like. Among them, tris(2,4-t-butylphenyl)phosphite (Irgafos (registered trademark) 168, manufactured by BASF) is preferable.

An antioxidant can be used individually by 1 type, or can be used in combination of 2 or more type.

When the film of the present invention contains an antioxidant, the content of the antioxidant in the film is, for example, 0.01% by mass or more and less than 0.5% by mass. The content is preferably 0.03% by mass or more and 0.45% by mass or less, more preferably 0.05% by mass or more and 0.4% by mass, from the viewpoint of safety function operability, dielectric breakdown strength, element winding suitability, etc. % by mass or less, more preferably 0.07% by mass or more and 0.35% by mass or less, and even more preferably 0.08% by mass or more and 0.32% by mass or less.

The film of the present invention preferably contains a styrenic thermoplastic elastomer from the viewpoint of security function operability, dielectric breakdown strength, element winding suitability, and the like.

The styrene-based thermoplastic elastomer is not particularly limited, and known ones can be used. By adding a styrenic thermoplastic elastomer, dielectric breakdown strength and folding crack resistance at high temperatures can be enhanced. A styrene-based thermoplastic elastomer usually has a styrene monomer polymer block (Hb) as a hard segment and a conjugated diene compound polymer block or its hydrogenated block (Sb) as a soft segment. The structure of this styrene-based thermoplastic elastomer includes a diblock structure represented by Hb--Sb, a triblock structure represented by Hb--Sb--Hb or Sb--Hb--Sb, and a structure represented by Hb--Sb--Hb--Sb. or a polyblock structure in which a total of 5 or more Hb and Sb are linearly bonded.

The styrenic monomer used in the styrene monomer polymer block (Hb) is not particularly limited, and examples thereof include styrene and derivatives thereof. Specifically, for example, styrene, α-methylstyrene, 2-methylstyrene, 4-methylstyrene, 4-propylstyrene, 4-t-butylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl- Styrenes such as 4-benzylstyrene, 4-(phenylbutyl)styrene, 2,4,6-trimethylstyrene, monofluorostyrene, difluorostyrene, monochlorostyrene, dichlorostyrene, methoxystyrene, t-butoxystyrene, 1-vinyl vinyl group-containing aromatic compounds such as vinylnaphthalenes such as naphthalene and 2-vinylnaphthalene; and vinylene group-containing aromatic compounds such as indene and acenaphthylene. Among these, styrene is preferred. Only one type of styrene monomer may be used, or two or more types may be used.

Moreover, the conjugated diene compound used for the conjugated diene compound polymer block (Sb) is not particularly limited either. Examples of such conjugated diene compounds include butadiene, isoprene, 2,3-dimethylbutadiene, pentadiene, and hexadiene. Among these, butadiene is preferred. The number of conjugated diene compounds may be one, or two or more. In addition, other comonomers such as ethylene, propylene, butylene, styrene can also be copolymerized. Also, the conjugated diene compound polymer block (Sb) may be a partially or completely hydrogenated hydrogenated product.

Specific examples of styrene-based thermoplastic elastomers include styrene-isoprene diblock copolymer (SI), styrene-butadiene diblock copolymer (SB), styrene-isoprene-styrene triblock copolymer (SIS), styrene -butadiene/isoprene-styrene triblock copolymers (SB/IS), and styrene-butadiene-styrene triblock copolymers (SBS) and hydrogenated forms thereof. Hydrogenates include, for example, styrene-ethylene-butylene-styrene copolymer (SEBS), styrene-ethylene-propylene-styrene copolymer (SEPS), and styrene-ethylene-ethylene-propylene-styrene copolymer (SEEPS). , styrene-butylene-butadiene-styrene copolymer (SBBS), and the like. Among these, hydrogenated products are preferred, and SEBS is particularly preferred.

The content of styrene monomer polymer block units (Hb) in the styrene-based thermoplastic elastomer is not particularly limited, but is, for example, 5% by mass or more and 80% by mass or less, preferably 25% by mass or more and 80% by mass or less, or more. It is preferably 30% by mass or more and 70% by mass or less, more preferably 35% by mass or more and 60% by mass or less.

The content of the conjugated diene compound polymer block and/or its hydrogenated block (Sb) (preferably ethylene-butylene) in the styrene-based thermoplastic elastomer is not particularly limited, but is, for example, 20% by mass or more and 95% by mass or less. is preferably 20% by mass or more and 75% by mass or less, more preferably 30% by mass or more and 70% by mass or less, and still more preferably 40% by mass or more and 65% by mass or less.

The melt mass flow rate of the styrenic thermoplastic elastomer is not particularly limited, and is, for example, 0.5 to 15 g/10 minutes. The melt mass flow rate is preferably 1 to 10 g/10 minutes, more preferably 1.5 to 5 g/10 minutes, still more preferably 2 to 4 g/10 minutes. The melt mass flow rate is measured according to JIS K 7210:1999 (conditions: 230°C, load 2.16 kg).

The styrene-based thermoplastic elastomer can be obtained as a commercial product, or can be produced by a known method. Examples of the styrene-based thermoplastic elastomer include Tuftec (registered trademark) series (eg H1517, etc.) manufactured by Asahi Kasei Corporation, Septon (registered trademark) series (eg, 8000 series) manufactured by Kuraray Co., Ltd., and the like. It can be used preferably.

The styrenic thermoplastic elastomers can be used singly or in combination of two or more.

When the film of the present invention contains a styrene-based thermoplastic elastomer, the content of the styrene-based thermoplastic elastomer is not particularly limited. It is preferable that the content in the film of the present invention is lower than that of the syndiotactic polystyrene-based resin and the polyphenylene ether-based resin, respectively.

When the film of the present invention contains a styrene-based thermoplastic elastomer, the content of the styrene-based thermoplastic elastomer in the film in one aspect is, for example, 1% by mass or more and 20% by mass or less, preferably 2% by mass or more and 18% by mass. % by mass or less, more preferably 3% by mass or more and 15% by mass or less, still more preferably 4% by mass or more and 12% by mass or less, even more preferably 5% by mass or more and 9% by mass or less, particularly preferably 5% by mass or more and 8% by mass % or less. When the film of the present invention contains a styrene-based thermoplastic elastomer, the content of the styrene-based thermoplastic elastomer in the film in another aspect is, for example, 5% by mass or more and 20% by mass or less, preferably 7% by mass. 18% by mass or less, particularly preferably 8% by mass or more and 16% by mass or less.

The film of the present invention may contain other resins, other additives, etc., in addition to the above components.

Other resins are not particularly limited. In one aspect, the film of the present invention preferably contains an atactic polystyrene resin as another resin. In another aspect, the film of the present invention preferably has a lower atactic polystyrene resin content (including 0% by mass).

The atactic polystyrene-based resin is not particularly limited as long as it is an amorphous resin having a polystyrene main chain with an atactic structure. As for the atactic polystyrene resin, 90% or more, more preferably 95% or more of the structural units constituting the main chain are preferably styrene and/or styrene having a substituent on the aromatic ring.

An atactic structure means that a phenyl group or a substituted phenyl group, which is a side chain with respect to a main chain formed from carbon-carbon bonds, has a random steric structure. Tacticity is usually quantified by nuclear magnetic resonance spectroscopy ( ¹³ C-NMR spectroscopy) using carbon isotopes, and the abundance ratio of a plurality of consecutive constitutional units, for example, dyads for two, triads for three, In the case of 5, it can be indicated by a pentad or the like. The atactic polystyrene resin is, for example, a racemic diad and has a syndiotacticity of, for example, less than 75%, preferably 65% or less. In addition, the atactic polystyrene resin is, for example, a racemic pentad and has a syndiotacticity of, for example, less than 30%, preferably 25% or less.

Specific examples of atactic polystyrene resins include polystyrene, poly(alkylstyrene), poly(halogenated styrene), poly(halogenated alkylstyrene), poly(alkoxystyrene), and mixtures thereof, or these. Examples thereof include copolymers as a main component.

Examples of poly(alkylstyrene) include poly(methylstyrene), poly(ethylstyrene), poly(isopropylstyrene), poly(tert-butylstyrene), poly(phenylstyrene), poly(vinylstyrene), poly(vinyl naphthalene) and the like. Examples of poly(halogenated styrene) include poly(chlorostyrene), poly(bromostyrene), poly(fluorostyrene) and the like. Examples of poly(halogenated alkylstyrene) include poly(chloromethylstyrene) and the like. Examples of poly(alkoxystyrene) include poly(methoxystyrene) and poly(ethoxystyrene).

Among these, particularly preferred atactic polystyrene resins include polystyrene, poly(p-methylstyrene), poly(m-methylstyrene), poly(p-tert-butylstyrene), poly(p-chlorostyrene), poly (m-chlorostyrene), poly(p-fluorostyrene), hydrogenated polystyrene and styrene-alkylstyrene copolymers such as copolymers of styrene and p-methylstyrene.

The melt mass flow rate of the atactic polystyrene resin is not particularly limited, and is, for example, 0.5 to 20 g/10 minutes. The melt mass flow rate is preferably 2-15 g/10 min, more preferably 4-12 g/10 min, and even more preferably 6-9 g/10 min. The melt mass flow rate is measured according to ISO 1133 (conditions: 200° C., load 5 kgf, test piece pellets).

Atactic polystyrene-based resins can be obtained as commercial products, or can be produced by known methods. As a commercial product of atactic polystyrene resin, a resin generally called general-purpose polystyrene (GPPS) can be preferably used. available as

Atactic polystyrene resins can be used singly or in combination of two or more.

The content of the atactic polystyrene-based resin is not particularly limited, but the resin is higher than the syndiotactic polystyrene-based resin (preferably, higher than the syndiotactic polystyrene-based resin and the polyphenylene ether-based resin). , the content in the film of the present invention is preferably low.

When the film of the present invention contains an atactic polystyrene resin, the content of the atactic polystyrene resin in the film is, for example, 1% by mass or more and 12% by mass or less, preferably 2% by mass or more and 10% by mass or less. , more preferably 3% by mass or more and 8% by mass or less, still more preferably 4% by mass or more and 7% by mass or less, and even more preferably 5% by mass or more and 7% by mass or less.

In one aspect, the content of the atactic polystyrene resin in the film of the present invention is, for example, 0% by mass or more and 12% by mass or less, preferably 0% by mass or more and 10% by mass or less, more preferably 0% by mass or more. It is 7% by mass or less, more preferably 0% by mass or more and 4% by mass or less, even more preferably 0% by mass or more and 1% by mass or less, and particularly preferably 0% by mass.

When the film of the present invention contains a resin other than the atactic polystyrene resin, the content of the resin other than the atactic polystyrene resin in the film of the present invention is, for example, 10% by mass or less, 5% by mass. 1% by mass or less, 0.5% by mass or less, and 0.1% by mass or less.

Other additives are not particularly limited, and include, for example, components that can be incorporated in resin films (especially resin films for capacitors), such as chlorine absorbers, lubricants, plasticizers, flame retardants, and colorants. etc. When the film of the present invention contains an additive, the content of the additive in the film of the present invention is, for example, 10% by mass or less, 5% by mass or less, 1% by mass or less, 0.5% by mass or less, 0 .1% by mass or less. The film of the present invention is a resin composition, the resin composition contains a syndiotactic polystyrene-based resin, a polyphenylene ether-based resin, and titanium oxide particles, and the syndiotactic The content of the polystyrene resin is 50% by mass or more, the content of the polyphenylene ether resin in the resin composition is 10% by mass or more, and the content of the titanium oxide particles in the film is Manufactured by a method including a step of forming a resin composition (in this specification, sometimes referred to as "the resin composition of the present invention") having a content of 0.55% by mass or more and 3% by mass or less. can do. For example, the resin composition of the present invention is extruded into a film (the resulting film of the present invention is sometimes referred to as the "unstretched film of the present invention"), and the unstretched film of the present invention is divided into two. The film of the present invention can be obtained by axially stretching (the film of the present invention obtained by this is sometimes referred to as "the biaxially stretched film of the present invention").

The composition of the resin composition of the present invention is the same as that of the film of the present invention.

The state of the resin composition of the present invention is not particularly limited. The state of the resin composition of the present invention may be, for example, a solid (for example, an aggregate of resin lumps (the size of which is not particularly limited, including pellets and powder)) or a liquid (for example, a molten mixture of each component). ) and the like.

The resin composition of the present invention preferably contains a blended resin (including a polymer alloy) obtained by blending some or all of the components in a molten state.

The resin composition of the present invention preferably contains a modified polyphenylene ether as a blended resin containing a polyphenylene ether-based resin. Modified polyphenylene ether is a resin obtained by melt-kneading (polymer alloying) a polyphenylene ether-based resin and another resin. Modified polyphenylene ether is preferable because it is excellent in melt fluidity and extrusion moldability.

Other resins constituting the modified polyphenylene ether include, for example, polystyrene-based resins, styrene-based thermoplastic elastomers, polypropylene-based resins, polyphenylene sulfide-based resins, and polyamide-based resins. Among these, polystyrene-based resins (preferably atactic polystyrene-based resins), styrene-based thermoplastic elastomers, and the like are preferable.

The composition ratio of each resin constituting the modified polyphenylene ether is not particularly limited, and can be appropriately adjusted according to the type of resin. The content of the polyphenylene ether resin in the modified polyphenylene ether is, for example, 40% by mass or more and 95% by mass or less, preferably 50% by mass or more and 90% by mass or less, more preferably 60% by mass or more and 85% by mass or less, still more preferably 65% by mass or more and 80% by mass or less, more preferably 65% by mass or more and 75% by mass or less, and the content of the other resin in the modified polyphenylene ether is, for example, 5% by mass or more and 60% by mass or less, preferably 10 % by mass to 50% by mass, more preferably 15% by mass to 40% by mass, even more preferably 20% by mass to 35% by mass, and even more preferably 25% by mass to 35% by mass.

The melt flow rate of the modified polyphenylene ether is not particularly limited, but from the viewpoint of extrusion moldability and continuous stretchability, it is preferably 1 to 20 g/10 minutes, more preferably 1 to 10 g/10 minutes, and 1 to 8 g/10 Minutes are more preferred. The melt flow rate (MFR) is measured according to condition M of JIS K 7210 using a melt indexer manufactured by Toyo Seiki Co., Ltd. Specifically, first, a sample weighed to 4 g is inserted into a cylinder set to a test temperature of 300° C. and preheated for 3.5 minutes under a load of 2.16 kg. After that, the weight of the sample extruded from the bottom hole for 30 seconds is measured to obtain the MFR (g/10 minutes). The above measurement is repeated three times, and the average value is taken as the measured value of MFR.

Modified polyphenylene ether can be obtained as a commercial product or can be produced by a known method. Examples of commercially available products include the Iupiace (registered trademark) series (for example, Iupiace (registered trademark) AH91) manufactured by Mitsubishi Engineering-Plastics Corporation, and the Zylon (registered trademark) manufactured by Asahi Kasei Corporation. Series (for example, Zylon (registered trademark) 1000H), trade name Noryl (registered trademark) series manufactured by SHPP Japan LLC, and the like can be suitably used.

Modified polyphenylene ethers can be used singly or in combination of two or more.

The content of the modified polyphenylene ether is not particularly limited as long as the final content of each component in the resin composition of the present invention reaches a predetermined amount. The content of the modified polyphenylene ether in the resin composition of the present invention is, for example, 5% by mass or more and 50% by mass or less, preferably 10% by mass or more and 45% by mass or less, more preferably 15% by mass or more and 40% by mass or less, and further It is preferably 20% by mass or more and 40% by mass or less.

In one embodiment, the resin composition of the present invention comprises two or more (preferably two) modified polyphenylene ethers ( For example, it is preferably a resin composition containing modified polyphenylene ether A and modified polyphenylene ether B). Therefore, the film of the present invention preferably includes a film-like molded layer of a resin composition containing two or more modified polyphenylene ethers having different melt flow rates. The film-shaped molding layer preferably constitutes at least one surface of the film of the invention, ie is arranged as the outermost layer.

The modified polyphenylene ether A preferably contains a polyphenylene ether-based resin and a polystyrene-based resin (preferably an atactic polystyrene-based resin).

The content of the polyphenylene ether resin in the modified polyphenylene ether A is, for example, 40% by mass or more and 95% by mass or less, preferably 50% by mass or more and 90% by mass or less, more preferably 60% by mass or more and 85% by mass or less, and even more preferably is 65% by mass or more and 80% by mass or less, more preferably 65% by mass or more and 75% by mass or less, and the content of the polystyrene resin (preferably atactic polystyrene resin) in the modified polyphenylene ether A is, for example, 5 % by mass or more and 60% by mass or less, preferably 10% by mass or more and 50% by mass or less, more preferably 15% by mass or more and 40% by mass or less, still more preferably 20% by mass or more and 35% by mass or less, still more preferably 25% by mass It is more than 35 mass % or less.

The melt flow rate of modified polyphenylene ether A is preferably 4.5 to 10 g/10 minutes, more preferably 4.8 to 8 g/10 minutes, even more preferably 5 to 7 g/10 minutes.

The content of the modified polyphenylene ether A is not particularly limited as long as the final content of each component in the resin composition of the present invention reaches a predetermined amount. The content of the modified polyphenylene ether A in the resin composition of the present invention is, for example, 3% by mass or more and 40% by mass or less, preferably 10% by mass or more and 35% by mass or less, more preferably 10% by mass or more and 30% by mass or less, More preferably, it is 15% by mass or more and 25% by mass or less.

The modified polyphenylene ether B preferably contains a polyphenylene ether resin and a styrene thermoplastic elastomer.

The content of the polyphenylene ether resin in the modified polyphenylene ether B is, for example, 40% by mass or more and 95% by mass or less, preferably 50% by mass or more and 90% by mass or less, more preferably 60% by mass or more and 85% by mass or less, and even more preferably is 65% by mass or more and 80% by mass or less, more preferably 65% by mass or more and 75% by mass or less, and the content of the styrene-based thermoplastic elastomer in the modified polyphenylene ether B is, for example, 5% by mass or more and 60% by mass or less. , preferably 10% by mass or more and 50% by mass or less, more preferably 15% by mass or more and 40% by mass or less, still more preferably 20% by mass or more and 35% by mass or less, still more preferably 25% by mass or more and 35% by mass or less .

The melt flow rate of modified polyphenylene ether B is preferably 1 to 4 g/10 minutes, more preferably 1.2 to 3.5 g/10 minutes, still more preferably 1.2 to 3 g/10 minutes, and 1.3 to 2 .5 g/10 min is even more preferred.

The content of the modified polyphenylene ether B is not particularly limited as long as the final content of each component in the resin composition of the present invention reaches a predetermined amount. The content of the modified polyphenylene ether B in the resin composition of the present invention is, for example, 2% by mass or more and 40% by mass or less, preferably 5% by mass or more and 30% by mass or less, more preferably 7% by mass or more and 20% by mass or less, More preferably, it is 7% by mass or more and 15% by mass or less.

In another aspect, the resin composition of the present invention is a resin containing one type of modified polyphenylene ether (especially modified polyphenylene ether B) from the viewpoint of safety function operability, dielectric breakdown strength, element winding suitability, etc. It is preferably a composition.

The resin composition of the present invention may contain a styrene-based thermoplastic elastomer alone. and a blend resin (blend resin Z) containing a syndiotactic polystyrene resin. More specifically, the resin composition of the present invention preferably contains a thermoplastic styrene-based elastomer melted together with a syndiotactic polystyrene-based resin.

The composition ratio of each resin constituting the blend resin Z is not particularly limited, and can be appropriately adjusted according to the type of resin. The content of the syndiotactic polystyrene resin in the blend resin Z is preferably 60% by mass or more and 95% by mass or less, more preferably 70% by mass or more and 90% by mass or less. From the same point of view, the content of the styrene-based thermoplastic elastomer in the blend resin Z is preferably 5% by mass or more and 40% by mass or less, more preferably 10% by mass or more and 30% by mass or less.

Blend resin Z can be used individually by 1 type, or can be used in combination of 2 or more types.

The content of the blend resin Z is not particularly limited as long as the final content of each component in the resin composition of the present invention reaches a predetermined amount. The content of the blended resin Z in the resin composition of the present invention is, for example, 1% by mass or more and 30% by mass or less, preferably 5% by mass or more and 25% by mass or less, more preferably 10% by mass or more and 20% by mass or less. .

A blended resin can be obtained by melt-kneading each component. As a method of melt-kneading, a single-screw type, twin-screw type, or multi-screw type melt-kneader of more than that type can be used. , has a high effect of improving the crackability of the film, and is preferably used. In the case of the twin-screw type, both co-rotation and counter-rotation kneading types can be used, but co-rotation is preferable from the viewpoint of suppressing resin deterioration. The screw diameter to length ratio (L/D) is preferably 20 or more, more preferably 25 or more, and even more preferably 28 or more. Although there is no upper limit to L/D, it is 100 or less, preferably 80 or less from the viewpoint of resin deterioration suppression.

The temperature during melt-kneading is preferably 250° C. to 350° C., more preferably 290° C. to 330° C., from the standpoint of the suppression of resin deterioration and dispersibility. During melt-kneading, it is preferable to purge the kneader with an inert gas such as nitrogen in order to suppress deterioration of the resin.

A method for extrusion molding the resin composition of the present invention is not particularly limited, and a known extrusion molding method can be employed. For example, the solid resin composition of the present invention supplied to the extruder is heated to a molten state, filtered through a filter, extruded into a film using a T-die, and placed on a cooling roll set to a predetermined surface temperature. A method of contact solidification and molding may be mentioned. After forming into a film, the unstretched film of the present invention can be made into a roll by winding it around a core.

The resin composition of the present invention is preferably mixed before being melted. The method of mixing is not particularly limited, but examples include a method of dry-blending a plurality of types of resin lumps (such as pellets) using a mixer or the like.

It is preferable to dry the resin composition of the present invention before melting. Drying conditions are not particularly limited. Although the drying temperature is not particularly limited, it is, for example, 70 to 150°C, preferably 80 to 130°C. The drying time can be appropriately adjusted according to the drying temperature, and is, for example, 2 to 50 hours, preferably 3 to 20 hours.

Melting of the resin composition of the present invention is usually carried out in an extruder. Extruders include, for example, a single-screw type, a twin-screw type, and a multi-screw type with three or more screws. In the case of two or more shafts, the type of screw rotation includes, for example, co-rotation and counter-rotation. The melting temperature is preferably 280 to 305°C, preferably 280 to 304°C, more preferably 285 to 302°C, still more preferably 290 to 302°C, even more preferably 295 to 302°C, particularly preferably 298 to 302°C. is. In order to suppress deterioration during kneading and mixing of the resin, it is preferable to purge the kneader with an inert gas such as nitrogen.

The filtration accuracy of the filter for filtering the resin composition of the present invention in a molten state is not particularly limited, but is, for example, 2 to 20 μm, preferably 3 to 10 μm, more preferably 3 to 7 μm.

The temperature during extrusion with a T-die is not particularly limited, but is preferably 280 to 305° C., preferably 280 to 304° C., more preferably 285 to 302° C., still more preferably 290 to 302° C., still more preferably 295 to 302°C, particularly preferably 298-302°C. As a result, the resin can be appropriately dispersed, which in turn contributes to safety function operability, dielectric breakdown strength, element winding aptitude, and the like.

There are no particular limitations on the method of contacting the film material extruded from the T-die when it is brought into contact with the cooling roll to solidify it. Examples thereof include air knife, electrostatic pinning, elastic roll nip, metal roll nip, and elastic metal roll nip. The cooling roll surface temperature is not particularly limited, but is, for example, 80 to 115°C, preferably 95 to 105°C.

Although the thickness of the unstretched film of the present invention is not particularly limited, it is, for example, 10 to 100 μm, preferably 20 to 60 μm.

The method for biaxially stretching the unstretched film of the present invention is not particularly limited, and a known biaxial stretching method can be employed. For example, the unstretched film of the present invention is heated with a heating roll and stretched in the machine direction (MD), then stretched in the width direction (TD) at a predetermined temperature, then heat-set at a predetermined temperature, and stretched in the width direction. A method of relaxing and cooling can be mentioned.

The temperature of the heating rolls before stretching in the machine direction is not particularly limited, but is, for example, 100 to 160°C, preferably 120 to 155°C, more preferably 140 to 150°C. The draw ratio in the machine direction is not particularly limited, but is, for example, 1.5 to 4.5 times, preferably 3.0 to 4.0 times.

The temperature during stretching in the width direction is not particularly limited, but is, for example, 120 to 180°C, preferably 140 to 170°C, more preferably 155 to 165°C. The draw ratio in the width direction is not particularly limited, but is, for example, 2 to 5 times, preferably 3.5 to 4.5 times.

The heat setting temperature is not particularly limited, but is, for example, 200 to 280°C, preferably 230 to 260°C. The heat setting time is not particularly limited, but is, for example, 5 to 20 seconds.

The temperature for relaxation (relaxation) in the width direction is not particularly limited, but is, for example, 100 to 160°C, preferably 120 to 140°C. The relaxation (relaxation) rate in the width direction is not particularly limited, but is, for example, 3 to 7%, preferably 4 to 6%.

Although the thickness of the film of the present invention is not particularly limited, it is, for example, 30 μm or less and 20 μm or less. The thickness is preferably thinner from the viewpoint of reducing the volume of the capacitor and increasing the capacitance. From this point of view, the thickness is preferably 10 μm or less, more preferably 9.5 μm or less, still more preferably 8 μm or less, even more preferably 6 μm or less, particularly preferably 5 μm or less, even more preferably 4 μm or less, particularly preferably 3 μm or less. In addition, the thickness is, for example, 1 μm or more, preferably 1.5 μm or more, more preferably 1.8 μm or more, and still more preferably 1.8 μm or more, from the viewpoint of further increasing dielectric breakdown strength and slit processability and further improving continuous film forming properties. It is 2 μm or more, more preferably 2.3 μm or more, and particularly preferably 2.5 μm or more. The thickness range of the film of the present invention can be set by arbitrarily combining the above upper and lower limits.

The thickness of the film of the present invention such as the unstretched film of the present invention and the biaxially stretched film of the present invention is measured using an outer micrometer (high-precision digimatic micrometer MDH-25MB manufactured by Mitutoyo Co., Ltd.) according to JIS K 7130: Measured according to the 1999 A method.

The layer structure of the film of the present invention is not particularly limited. The film of the present invention may be a single layer consisting of one layer, or may be multiple layers having the same or different compositions. The film of the present invention is preferably a film comprising one or more film-like molded layers of the resin composition of the present invention, and more preferably a single-layer film (one layer of the film-like resin composition of the present invention). It is a film consisting of a molded layer).

In the film of the present invention, from the viewpoint of safety function operability, dielectric breakdown strength, element winding suitability, etc., it is preferable that the protruding peak height Spk of at least one surface is 0.05 μm or more and 0.30 μm or less. The protruding peak height Spk is preferably 0.06 μm or more and 0.30 μm or less, more preferably 0.07 μm or more and 0.25 μm, from the viewpoint of safety function operability, dielectric breakdown strength, element winding suitability, etc. or less, more preferably 0.09 μm or more and 0.23 μm or less, still more preferably 0.10 μm or more and 0.21 μm or less, particularly preferably 0.11 μm or more and 0.20 μm or less, and even more preferably is 0.11 μm or more and 0.18 μm or less.

The protruding peak height Spk is a value defined by ISO25278-2 and measured as follows. "VertScan 2.0 (model: R5500GML)" manufactured by Ryoka Systems Co., Ltd. is used as an optical interferometric non-contact surface shape measuring instrument. As a sample for measurement, the film is cut into an arbitrary size of about 20 cm square, and with wrinkles sufficiently smoothed out, is set on a measurement stage using an electrostatic contact plate or the like. First, WAVE mode is used for measurement, a 530 white filter and a 1×BODY lens barrel are applied, and a 10× objective lens is used to measure per field of view (470.92 μm×353.16 μm). This operation is performed at 5 points at intervals of 1 cm in the flow direction from the central point in both the flow direction and the width direction of the chill roll side surface of the target sample. Next, the obtained data is subjected to noise removal processing using a median filter (3×3), and then to Gaussian filtering processing using a cutoff value of 30 μm to remove undulation components. As a result, the state of the roughened surface can be appropriately measured. Next, analysis is performed using the "ISO parameter" in the plug-in function "bearing" of the analysis software "VS-Viewer" of "VertScan 2.0", Spk (μm) is obtained, and obtained at the above 10 points Calculate the average value of each value.

From the viewpoint of safety function operability, the film of the present invention preferably has a thermal shrinkage rate of 10% or less as measured by the method described in the examples, even when measured in the film production direction (flow direction). . By setting the heat shrinkage ratio within this range, when the film is wound to form a capacitor, even when used in a high-temperature environment, deterioration of safety function operability due to tight winding is less likely to occur, which is preferable. The heat shrinkage rate is preferably 8% or less, more preferably 7% or less, even more preferably less than 6.5%, particularly preferably 6% or less. The lower limit is preferably 1% or more, more preferably 2% or more, and even more preferably 3% or more, from the viewpoint of suppressing slackness of the film due to heat during vapor deposition. The heat shrinkage rate in the direction (width direction) perpendicular to the film-forming direction of the film is preferably 0% or more and 6% or less, and preferably 1% or more and 5% or less.

The thermal shrinkage rate as described above can be achieved by controlling the combination of the resins of the present invention, the film-forming conditions, particularly the stretching ratio, the stretching speed, the heating (heat setting, etc.) temperature after stretching, the width relaxation rate, and the like.

The film of the present invention can provide a capacitor with excellent safety function operability. Security function operability, measured according to the method of the Examples below. The number of elements that does not cause a short circuit failure until the capacitance change rate is -90% is preferably 4 or more, more preferably 5 or more, and still more preferably 6 out of 6 elements.

The potential gradient when the capacitance change rate reaches -20% is preferably 280 V/μm or more, more preferably 310 V/μm or more, still more preferably 330 V/μm or more, still more preferably 350 V/μm or more, and particularly preferably It is 370 V/μm or more, more preferably 380 V/μm or more, and particularly preferably 390 V/μm or more. The upper limit of the potential frequency is not particularly limited, and is, for example, 450 V/μm, 430 V/μm, 420 V/μm, 410 V/μm, or 405 V/μm.

The film of the present invention has high dielectric breakdown strength at high temperatures. The dielectric breakdown strength is measured according to the method of Examples described later.

The dielectric breakdown strength of the film of the present invention in a 120° C. environment is preferably 480 V _DC /μm or more, more preferably 490 V _DC /μm or more, still more preferably 500 V _DC /μm or more, and even more preferably 510 V _DC /μm. above, and particularly preferably above 520 V _DC /μm.

The dielectric breakdown strength of the film of the present invention in a 150° C. environment is preferably 470 V _DC /μm or more, more preferably 480 V _DC /μm or more, still more preferably 490 V _DC /μm or more, and even more preferably 500 V _DC /μm. Above, particularly preferably 510 V _DC /μm or more, particularly more preferably 520 V _DC /μm or more.

The upper limit of dielectric breakdown strength at each temperature is not particularly limited, and is, for example, 650 V _DC /μm, 620 V _DC /μm, 600 V _DC /μm, 580 V _DC /μm, or 560 V _DC /μm.

The films of the present invention have a lower rate of change in dielectric breakdown strength with increasing temperature.

The ratio of the dielectric breakdown strength in a 150°C environment to the dielectric breakdown strength in a 120°C environment (dielectric breakdown strength in a 150°C environment/dielectric breakdown strength in a 120°C environment) is preferably 0.92. 0.94 or more, more preferably 0.95 or more, even more preferably 0.96 or more, particularly preferably 0.97 or more, and particularly preferably 0.98 or more.

Although the 120° C. environment and the 150° C. environment are the same “high temperature” environment, the load related to dielectric breakdown strength usually differs greatly. According to the present invention, it is possible to exhibit and/or maintain a higher dielectric breakdown strength even under a heavy load environment of 150°C.

The upper limit of each ratio described above is not particularly limited, and is, for example, 1.1, 1.05, or 1.0.

The film of the present invention has good element winding aptitude. The element winding aptitude is measured according to the method described in Examples below. The ratio of the number of rejected products to the total number of manufactured products is preferably 80% or more, more preferably 90% or more.

Applications of the film of the present invention are not particularly limited. The film of the present invention can be used, for example, as a heat-resistant film by taking advantage of its heat resistance. In addition, the film of the present invention (especially the biaxially stretched film of the present invention) can be suitably used as a capacitor film capable of exhibiting its properties. In particular, the film of the invention (particularly the biaxially stretched film of the invention) is used in a high-temperature environment, and is used in small-sized and high-capacity (for example, 5 μF or more, preferably 10 μF or more, more preferably 20 μF or more) capacitors. It can be used very preferably.

2. In one aspect of the present invention, a metal layer-integrated film (hereinafter referred to as "the present invention (also referred to as "metal layer integrated film"). This will be explained below.

The films of the present invention can be provided with metal layers (eg electrodes) on one or both sides for processing as capacitors. Such a metal layer is not particularly limited as long as the desired capacitor of the present invention can be obtained. It is preferable to form (laminate) a metal layer directly on both sides to form a metal layer-integrated film.

Methods for laminating a metal layer on the surface of the film of the present invention include, for example, metal vapor deposition, vacuum plating such as sputtering, coating and drying of a metal-containing paste, and pressure bonding of metal foil or metal powder. Among them, the vacuum deposition method and the sputtering method are preferred in order to meet the further demands for smaller and lighter capacitors, and the vacuum deposition method is preferred from the viewpoint of productivity and economic efficiency. Examples of the vacuum deposition method include the crucible method and the wire method in general, but there is no particular limitation as long as the desired capacitor of the present invention can be obtained, and an optimum method can be selected as appropriate. be able to.

The metal used for the metal layer can be, for example, single metals such as zinc, lead, silver, chromium, aluminum, copper, and nickel, mixtures of multiple types thereof, and alloys thereof. , economy and capacitor performance, zinc and aluminum are preferred.

The film resistance of the metal layer is preferably about 1 to 100Ω/□ from the viewpoint of the electrical characteristics of the capacitor. Even within this range, a high value is desirable from the viewpoint of self-healing (self-repairing) characteristics, and the membrane resistance is more preferably 5Ω/□ or more, and still more preferably 10Ω/□ or more. From the viewpoint of safety as a capacitor, the film resistance is more preferably 50Ω/□ or less, more preferably 30Ω/□ or less.

When forming an electrode (deposited metal film) by a vacuum vapor deposition method, the film resistance can be measured during vapor deposition, for example, by a four-probe method known to those skilled in the art. The film resistance of the vapor deposited metal film can be adjusted, for example, by adjusting the output of the evaporation source to adjust the amount of evaporation.

When forming a vapor-deposited metal film on one side of the film, an insulating margin is formed without vapor-depositing a certain width from one end of the film so that the film will form a capacitor when the film is wound. Furthermore, in order to strengthen the joint between the metal layer integrated film and the metallikon electrode, it is preferable to form a heavy edge structure at the end opposite to the insulating margin, and the film resistance of the heavy edge is usually 1 to 8 Ω/□. It is preferably about 1 to 5 Ω/□. Although the thickness of the heavy edge metal film is not particularly limited, it is preferably 1 to 200 nm.

There is no particular limitation on the vapor deposition pattern (margin pattern) of the metal vapor deposition film to be formed, but from the point of view of improving characteristics such as security of the capacitor, a pattern including a so-called special margin such as a fishnet pattern or a T margin pattern may be used. A fuse is preferably formed. Forming a vapor-deposited metal film with a vapor deposition pattern including a special margin on at least one side of the film of the present invention improves the security of the resulting capacitor, and is effective in terms of suppressing capacitor breakage and short-circuiting, and is therefore preferable. .

As a method for forming the margin, a known method such as a tape method of masking with a tape during vapor deposition, an oil method of masking by applying oil, or the like can be used without any limitation.

A protective layer may be provided on the metal layer-integrated film of the present invention for the purpose of physical protection of the metal vapor deposition film, moisture absorption prevention, oxidation prevention, and the like. Silicone oil, fluorine oil, or the like can be preferably used as the protective layer.

The metal layer-integrated film of the present invention can be processed into a capacitor of the present invention, which will be described later. The metal layer-integrated film of the present invention can also be used, for example, as a barrier film against oxygen and other gases.

3. Capacitor In one aspect, the present invention relates to a capacitor (in this specification, sometimes referred to as "capacitor of the present invention") containing the film of the present invention or the metal layer-integrated film of the present invention. This will be explained below.

In such a capacitor, the film of the present invention can be used as a capacitor dielectric film by, for example, (i) using the metal layer integrated film described above, (ii) the film of the present invention having no electrodes, or the like. (e.g., metal foils, films of the present invention metallized on one or both sides, paper and other plastic films metallized on one or both sides, etc.).

Film winding processing is performed in the process of manufacturing a capacitor. For example, a pair of two films of the present invention are arranged so that the metal films in the metal layer integrated film of the present invention and the film of the present invention are alternately laminated, and furthermore, the insulating margin portions are on opposite sides. The metal layer-integrated film is overlaid and wound. At this time, it is preferable to stack two sheets of the metal layer-integrated film of the present invention as a pair while shifting them by 1 to 2 mm. The winding machine to be used is not particularly limited, and for example, an automatic winding machine 3KAW-N2 type manufactured by Kaito Seisakusho Co., Ltd. can be used.

The film winding process is not limited to the above method, and other methods, for example, the film of the present invention vapor-deposited on both sides (in that case, the heavy edges are arranged at the opposite ends on the front and back sides). , non-vapor-deposited films of the present invention (having a narrower width of 2 to 3 mm than the double-sided vapor-deposited films of the present invention) may be alternately laminated and wound.

In the case of producing flat capacitors, after winding, the resulting winding is usually pressed. Promoting tight winding and element molding of the capacitor by pressing. From the viewpoint of controlling and stabilizing the interlayer gap, the applied pressure is 2 to 20 kg/cm ² although the optimum value varies depending on the thickness of the film of the present invention.

Subsequently, a capacitor is produced by thermally spraying a metal on both end surfaces of the winding to provide metallikon electrodes.

A predetermined heat treatment is further applied to the capacitor. That is, the present invention includes a step of subjecting the capacitor to heat treatment (hereinafter sometimes referred to as "thermal aging"). The heat treatment temperature is not particularly limited, but is, for example, 80 to 190.degree. The method of heat-treating the capacitor may be appropriately selected from known methods including, for example, a method using a constant temperature bath and a method using high-frequency induction heating under a vacuum atmosphere. The time for heat treatment is preferably 1 hour or more, more preferably 10 hours or more, in terms of obtaining mechanical and thermal stability, but it prevents molding defects such as heat wrinkles and mold attachment. 20 hours or less is more preferable.

The effect of thermal aging can be obtained by applying heat treatment. Specifically, the gaps between the films constituting the capacitor based on the metal layer-integrated film of the present invention are reduced, corona discharge is suppressed, and the internal structure of the metal layer-integrated film of the present invention is changed to crystallize. progresses. As a result, it is considered that the withstand voltage is improved. If the temperature of the heat treatment is lower than the predetermined temperature, the effects of heat aging cannot be sufficiently obtained. On the other hand, if the temperature of the heat treatment is higher than the predetermined temperature, the film of the present invention may be thermally decomposed or deteriorated by oxidation.

Lead wires are usually welded to the metallikon electrodes of heat aged capacitors. Moreover, in order to provide weather resistance and, in particular, to prevent moisture deterioration, it is preferable to enclose the capacitor in a case and pot it with an epoxy resin.

The capacitor of the present invention using the film of the present invention is suitably used in a high-temperature environment, and is a compact, high-capacity (for example, 5 μF or more, preferably 10 μF or more, more preferably 20 μF or more) capacitor. be able to. Therefore, the capacitor of the present invention can be used as a high-voltage capacitor, various switching power sources, filter capacitors and smoothing capacitors for converters and inverters, etc., which are used in electronic devices and electrical devices. In addition, the capacitor of the present invention can be suitably used as an inverter capacitor, a converter capacitor, and the like for controlling drive motors of electric vehicles, hybrid vehicles, and the like, for which demand has been increasing in recent years.

EXAMPLES The present invention will be described in detail below based on examples, but the present invention is not limited by these examples.

(1) Measuring method Various measuring methods are as follows.

(1-1) Measurement of average particle size The average particle size of inorganic particles (titanium oxide (TiO ₂ ), silica, spherical silicone) was measured as follows. The powder is scattered on the sample stage so that the individual particles do not overlap as much as possible, and an ultra-high resolution field emission scanning electron microscope ((FE-SEM) Hitachi High Technologies S-5200) is used to measure at least 100 Each particle was observed at a magnification of 10,000 to 30,000 to obtain an observed image. The longest diameter was measured from the observed image using image analysis software, and the measured values were averaged to obtain the average particle diameter.

(1-2) Melt flow rate measurement For each resin, the melt flow rate (MFR) in the form of raw resin pellets was measured according to JIS K 7210 condition M using a melt indexer manufactured by Toyo Seiki Co., Ltd. . Specifically, first, a sample weighed to 4 g was inserted into a cylinder set to a test temperature of 300° C. and preheated for 3.5 minutes under a load of 2.16 kg. After that, the weight of the sample extruded from the bottom hole was measured for 30 seconds to obtain the MFR (g/10min). The above measurements were repeated three times, and the average value was taken as the measured value of MFR.

(1-3) Measurement and calculation of the content of each component in the biaxially stretched film When is known, it was calculated from the content and the blending ratio of the raw materials. When a blended resin and/or modified polyphenylene ether with unknown component content was used as a raw material, the content of each component in the raw material was measured by the following method, and the content was calculated from the content and the blending ratio of the raw materials. When the content ratio of raw materials was unknown, the content ratio of each component in the biaxially stretched film was measured by the following method.

A raw material or a biaxially stretched film dissolved in 1,1,2,2-tetrachloroethane-d ₂ was used as a measurement sample, and ¹ H-NMR measurement and ¹³ C-NMR measurement were performed. Conditions for ¹ H-NMR measurement and ¹³ C-NMR measurement are shown below.

In the ¹³ C-NMR measurement, the contained components were identified from the measured signals. Thereafter, the integrated intensity ratio (molar ratio) per H atom of each contained component was determined from the signals measured by ¹ H-NMR measurement, and converted into a weight ratio by the formula weight of each component, polyphenylene ether component, styrene component and the content of ethylene-butylene component were determined.

Here, the content of the polyphenylene ether resin in the biaxially stretched film is equal to the content of the polyphenylene ether component determined above.

[ ¹ H-NMR measurement]
Measuring device: AVANCE III-600 with Cryo Probe manufactured by Bruker Biospin
Measurement frequency: 600MHz
Measurement solvent: 1,1,2,2-tetrachloroethane- _d2
Measurement temperature: 300K
Chemical shift standard: 1,1,2,2-tetrachloroethane-d ₂ ( ¹ H; 6.00 ppm)
[ ¹³ C-NMR measurement]
Measuring device: AVANCE III-600 with Cryo Probe manufactured by Bruker Biospin
Measurement frequency: 150MHz
Measurement solvent: 1,1,2,2-tetrachloroethane- _d2
Measurement temperature: 300K
Chemical shift standard: 1,1,2,2-tetrachloroethane-d ₂ ( ¹³ C; 73.78 ppm).

(1-4) Measurement of ethylene-butylene content in SEBS The content of ethylene-butylene in the SEBS type hydrogenated styrenic thermoplastic elastomer, which is the resin used in Examples and Comparative Examples, was measured as follows. did. A solution of SEBS in deuterated chloroform (CDCl ₃ ) was used as a measurement sample, and ¹ H-NMR measurement was performed under the following conditions. Identify the component from the measured signal, determine the integrated intensity ratio (molar ratio) per H atom of each component, convert to a weight ratio by the formula weight of each component, and calculate the content of ethylene-butylene. asked.

[ ¹ H-NMR measurement]
Measuring device: AVANCE III-600 with Cryo Probe manufactured by Bruker Biospin
Measurement frequency: 600MHz
Measurement solvent: _CDCl3
Measurement temperature: 300K
Chemical shift standard: _CDCL3 ( ^1H ; 7.25 ppm).

(2) Preparation of resin composition and film
(2-1) Used resin, etc.
・(A) Syndiotactic polystyrene resin (sPS)
A1: Zarek (registered trademark) 90ZC manufactured by Idemitsu Kosan Co., Ltd.

・(B) Polyphenylene ether resin (PPE)
B1: Iupiace (registered trademark) PX100F manufactured by Mitsubishi Engineering-Plastics Corporation
B2: Iupiace (registered trademark) PX100L manufactured by Mitsubishi Engineering-Plastics Corporation

・(C) SEBS type hydrogenated styrene thermoplastic elastomer C1: Tuftec (registered trademark) H1517 manufactured by Asahi Kasei Corporation (ethylene-butylene content = 57%)

・(D) atactic polystyrene (aPS)
D1: HF77 manufactured by PS Japan Co., Ltd.

(E) Titanium oxide (titanium dioxide: TiO ₂ )
E1: PT-501R manufactured by Ishihara Sangyo Co., Ltd.
E2: PT-401L manufactured by Ishihara Sangyo Co., Ltd.
E3: R-38L manufactured by Sakai Chemical Industry Co., Ltd.

・ (F) Silica F3: Seahoster (registered trademark) KE P100 manufactured by Nippon Shokubai Co., Ltd.

・ (G) Spherical silicone G1: (registered trademark) Tospearl 120FL manufactured by Momentive Performance Materials Japan LLC

・ (H) Antioxidant H1: BASF Japan Ltd. Irganox (registered trademark) 1010 (hindered phenolic antioxidant)
H2: Irgafos (registered trademark) 168 (phosphorus antioxidant) manufactured by BASF Japan Ltd.

(2-2) Blend resin
・Modified polyphenylene ether resin 1 (m-PPE1)
B1 and D1 were mixed and charged into a twin-screw melt kneader (2D30W2, L/D=30, manufactured by Toyo Seiki Seisakusho Co., Ltd.) together with nitrogen gas. The mixture was melt-kneaded at a cylinder temperature of 320° C. and a rotation speed of 100 rpm, and extruded through a strand die. After cooling the strand with water, it was cut into pellets to obtain m-PPE1. The MFR at 300° C. and 2.16 kg load was 5.7 g/10 min.

・Modified polyphenylene ether resin 2 (m-PPE2)
B2 and C1 were mixed and put into a twin-screw melt kneader (2D30W2, L/D=30, manufactured by Toyo Seiki Seisakusho Co., Ltd.) together with nitrogen gas. The mixture was melt-kneaded at a cylinder temperature of 320° C. and a rotation speed of 100 rpm, and extruded through a strand die. After cooling the strand with water, it was cut into pellets to obtain m-PPE2. The MFR at 300° C. and 2.16 kg load was 1.8 g/10 min.

・Particle-containing blend resin 1 (Z1)
A1, C1, E1, H1, and H2 were mixed by appropriately changing the mixing ratio (the mass ratio of H1 and H2 was 1:2) to obtain a plurality of mixtures with different mixing ratios of each component. Each mixture was charged into a twin-screw melt kneader (2D30W2, L/D=30, manufactured by Toyo Seiki Seisakusho Co., Ltd.) together with nitrogen gas. The mixture was melt-kneaded at a cylinder temperature of 300° C. and a rotation speed of 100 rpm, and extruded from a strand die. After cooling the strand with water, it was cut into pellets to obtain Z1.

・Particle-containing blend resin 2 (Z2)
A1, C1, E2, H1 and H2 are mixed (the mass ratio of H1 and H2 is 1:2), and a twin-screw type melt kneader (2D30W2, L/D = 30 manufactured by Toyo Seiki Seisakusho Co., Ltd.) , was introduced with nitrogen gas. The mixture was melt-kneaded at a cylinder temperature of 300° C. and a rotation speed of 100 rpm, and extruded from a strand die. After cooling the strand with water, it was cut into pellets to obtain Z2.

- Particle-containing blend resin 3 (Z3)
A1, C1, E3, H1, and H2 are mixed (the mass ratio of H1 and H2 is 1:2), and a twin screw type melt kneader (2D30W2, L/D = 30, manufactured by Toyo Seiki Seisakusho Co., Ltd.) , was introduced with nitrogen gas. The mixture was melt-kneaded at a cylinder temperature of 300° C. and a rotation speed of 100 rpm, and extruded from a strand die. After cooling the strand with water, it was cut into pellets to obtain Z3.

・Particle-containing blend resin 4 (Z4)
A1, B2, G1, and H1 were mixed and charged into a twin-screw melt kneader (2D30W2, L/D=30, manufactured by Toyo Seiki Seisakusho Co., Ltd.) together with nitrogen gas. The mixture was melt-kneaded at a cylinder temperature of 300° C. and a rotation speed of 100 rpm, and extruded from a strand die. After the strand was cooled with water, it was cut into pellets to obtain Z4.

- Particle-containing blend resin 5 (Z5)
A1, F3, and H1 were mixed, and charged into a twin-screw melt kneader (manufactured by Toyo Seiki Seisakusho Co., Ltd. 2D30W2, L/D=30) together with nitrogen gas. The mixture was melt-kneaded at a cylinder temperature of 300° C. and a rotation speed of 100 rpm, and extruded from a strand die. After cooling the strand with water, it was cut into pellets to obtain Z5.

・SEBS-containing blended resin (Y)
A1 and C1 were mixed and charged into a twin-screw melt kneader (2D30W2, L/D=30, manufactured by Toyo Seiki Seisakusho Co., Ltd.) together with nitrogen gas. The mixture was melt-kneaded at a cylinder temperature of 300° C. and a rotation speed of 100 rpm, and extruded from a strand die. After cooling the strand with water, it was cut into pellets to obtain Y.

(2-3) Method for preparing resin composition and film [Example 1]
[Production of unstretched sheet]
A resin composition obtained by mixing A1, m-PPE1, m-PPE2, and Z1 so that each component has the content shown in Table 2 was put into a pellet dryer and dried at 120 ° C. for 5 hours. . The dry raw material was put into a single-screw type film forming machine (GM-50 manufactured by GM Engineering Co., Ltd.) together with nitrogen gas. After melting at a cylinder temperature of 300°C, the mixture was filtered through a filter with a filtration accuracy of 5 µm, adjusted to 300°C, and extruded through a T-die at 300°C. The molten resin was solidified in contact with a mirror surface metal roll (cooling roll) having a surface temperature of 100° C. by an electrostatic adhesion method, and formed into a film to obtain an unstretched film. The thickness of the unstretched film was about 40 μm, but fine adjustment was made by changing the extrusion amount and the take-up speed so that the thickness after stretching would be the target value.

[Production of stretched film]
The unstretched film was introduced into a roll type longitudinal stretching machine, heated with rolls at 145° C., and stretched 3.5 times in the machine direction (MD). Then, it was introduced into a tenter and stretched 3.9 times in the width direction (TD) in an oven with the temperature of the stretching zone set at 158°C. Then, it was heat-set in an oven set at 240°C, and relaxed by 5% in the width direction in an oven set at 130°C. The ends of the film coming out of the tenter were slit and wound up to obtain a biaxially stretched film roll. The extrusion rate and take-up speed were finely adjusted so that the thickness of the film was 2.9 μm.

[Example 2]
A resin composition obtained by mixing A1, m-PPE1, m-PPE2, and Z1 so that each component has the content in Table 2 is used, and the film-forming conditions are the conditions in Table 1, and other was carried out in the same manner as in Example 1 to obtain an unstretched film and a biaxially stretched film having a thickness of 2.9 μm.

[Example 3]
A resin composition obtained by mixing A1, m-PPE1, m-PPE2, and Z1 so that each component has the content in Table 2 is used, and the film-forming conditions are the conditions in Table 1, and other was carried out in the same manner as in Example 1 to obtain an unstretched film and a biaxially stretched film having a thickness of 2.9 μm.

[Example 4]
A resin composition obtained by mixing A1, m-PPE1, m-PPE2, and Z1 so that each component has the content in Table 2 is used, and the film-forming conditions are the conditions in Table 1, and other was carried out in the same manner as in Example 1 to obtain an unstretched film and a biaxially stretched film having a thickness of 2.9 μm.

[Example 5]
A resin composition obtained by mixing A1, m-PPE1, m-PPE2, and Z1 so that each component has the content in Table 2 is used, and the film-forming conditions are the conditions in Table 1, and other was carried out in the same manner as in Example 1 to obtain an unstretched film and a biaxially stretched film having a thickness of 2.9 μm.

[Example 6]
A resin composition obtained by mixing A1, m-PPE1, m-PPE2, and Z2 so that each component has the content in Table 2 is used, and the film-forming conditions are the conditions in Table 1, and other was carried out in the same manner as in Example 1 to obtain an unstretched film and a biaxially stretched film having a thickness of 2.9 μm.

[Example 7]
A resin composition obtained by mixing A1, m-PPE1, m-PPE2, and Z3 so that each component has the content in Table 2 is used, and the film-forming conditions are the conditions in Table 1, and other was carried out in the same manner as in Example 1 to obtain an unstretched film and a biaxially stretched film having a thickness of 2.9 μm.

[Example 8]
A resin composition obtained by mixing A1, m-PPE1, m-PPE2, and Z1 so that each component has the content in Table 2 is used, and the film-forming conditions are the conditions in Table 1, and other was carried out in the same manner as in Example 1 to obtain an unstretched film and a biaxially stretched film having a thickness of 2.9 μm.

[Example 9]
A resin composition obtained by mixing A1, m-PPE1, m-PPE2, and Z1 so that each component has the content in Table 2 is used, and the film-forming conditions are the conditions in Table 1, and other was carried out in the same manner as in Example 1 to obtain an unstretched film and a biaxially stretched film having a thickness of 2.9 μm.

[Example 10]
A resin composition obtained by mixing A1, m-PPE1, m-PPE2, and Z1 so that each component has the content in Table 2 is used, and the film-forming conditions are the conditions in Table 1, and other was carried out in the same manner as in Example 1 to obtain an unstretched film and a biaxially stretched film having a thickness of 2.9 μm.

[Example 11]
A resin composition obtained by mixing A1, m-PPE1, m-PPE2, and Z1 so that each component has the content in Table 2 is used, and the film-forming conditions are the conditions in Table 1, and other was carried out in the same manner as in Example 1 to obtain an unstretched film and a biaxially stretched film having a thickness of 2.9 μm.

[Example 12]
A resin composition obtained by mixing A1, m-PPE2, and Z1 so that each component has the content shown in Table 2 was used, and the film-forming conditions were the conditions shown in Table 1, except for Example 1. An unstretched film and a biaxially stretched film having a thickness of 2.9 μm were obtained in the same manner as above.

[Comparative Example 1]
An unstretched film and a biaxially stretched film having a thickness of 2.9 μm were obtained in the same manner as in Example 1 except that Z4 was used as the resin composition and the film forming conditions were those shown in Table 1.

[Comparative Example 2]
An unstretched film and a biaxially stretched film having a thickness of 2.9 μm were obtained in the same manner as in Example 1 except that Z5 was used as the resin composition and the film-forming conditions were those shown in Table 1.

[Comparative Example 3]
A resin composition obtained by mixing A1, m-PPE1, and Y so that each component has the content shown in Table 2 was used, and the film-forming conditions were the conditions shown in Table 1, except for Example 1. An unstretched film and a biaxially stretched film having a thickness of 2.9 μm were obtained in the same manner as above.

(3) Measurement and evaluation of film forming properties and film properties
(3-1) Evaluation of film formation stability From the film formation length that can be formed without breakage when biaxially stretched films are formed under the conditions described in each example or comparative example, the film can be produced according to the following criteria. Membrane stability was evaluated.
⊚: Film forming length is 2000 m or more.
◯: Film formation length is 1000 m or more and less than 2000 m.
Δ: Film formation length is 500 m or more and less than 1000 m.
x: Film formation length is less than 500 m.

(3-2) Measurement of dielectric breakdown strength at high temperature The dielectric breakdown strength of the biaxially oriented films of Examples and Comparative Examples was evaluated as follows. A measuring apparatus was prepared according to JIS C2151:2006, 17.2.2 (plate electrode method). However, as the lower electrode, conductive rubber (E12S10 manufactured by Seiwa Denki Co., Ltd.) was used instead of the elastic body described in JIS C2151:2006, 17.2.2, and aluminum foil was not wound. The measurement environment was set in a forced circulation oven with a set temperature of 120° C. or 150° C., and the electrode and film were used after adjusting the temperature in the same oven for 30 minutes. The voltage was increased at a rate of 100 V/sec starting from 0 V, and the time when the current value exceeded 5 mA was defined as the breaking point. The dielectric breakdown voltage was measured 20 times, and the dielectric breakdown voltage value _VDC was divided by the film thickness (μm). was defined as dielectric breakdown strength (V _DC /μm).

(3-3) Measurement of Height Spk of Protruding Peaks The height Spk of protruding peaks of the biaxially stretched films of Examples and Comparative Examples was measured as follows.

"VertScan 2.0 (model: R5500GML)" manufactured by Ryoka Systems Co., Ltd. was used as an optical interferometric non-contact surface shape measuring instrument. As a sample for measurement, the film was cut into an arbitrary size of about 20 cm square, and with wrinkles sufficiently smoothed out, was set on a measurement stage using an electrostatic contact plate or the like.

First, WAVE mode was used for measurement, a 530 white filter and a 1×BODY lens barrel were applied, and a 10× objective lens was used to measure per field of view (470.92 μm×353.16 μm). This operation was performed at 5 points at 1 cm intervals in the flow direction from the central point in both the flow direction and the width direction of the chill roll side surface of the target sample.

Next, the obtained data was subjected to noise removal processing using a median filter (3×3), and then subjected to Gaussian filtering processing with a cutoff value of 30 μm to remove undulation components. This made it possible to appropriately measure the state of the roughened surface.

Next, analysis is performed using the "ISO parameter" in the plug-in function "bearing" of the analysis software "VS-Viewer" of "VertScan 2.0", Spk (μm) is obtained, and obtained at the above 10 points The average value of each value was calculated.

(3-4) Measurement of Thermal Shrinkage A strip of film (2 cm×15 cm with the long side in the measurement direction) was marked with a 10 cm long marked line. After suspending the strip-shaped film in a hot air oven at 200°C for 10 minutes, it was taken out from the oven and allowed to cool to room temperature (23°C). The marked line length after the treatment was measured, and the thermal shrinkage rate (longitudinal direction and transverse direction) of the film was determined. It was calculated by averaging the shrinkage ratios calculated by the following formula, with three sheets per measurement. (marked line length after treatment−marked line length before treatment)/marked line length before treatment (unit: %).

(4) Measurement and evaluation of capacitor characteristics
(4-1) Production of Capacitor Using the biaxially stretched films of Examples and Comparative Examples, capacitors were produced as follows. A special deposition pattern margin and insulation margin are formed on the biaxially stretched film to provide film capacitor security, and aluminum deposition is performed so that the surface resistivity of the metal film is 20 Ω / square. A figure film was obtained. Next, after slitting the metal layer-integrated film to a width of 30 mm, the two metal layer-integrated films are combined, and an automatic winder 3KAW-N2-60/83 type manufactured by Kaito Seisakusho Co., Ltd. is used. The number of turns was set so that the capacitance was 10 μF, and the metal layer integrated film was wound. After flattening the wound element by pressing, zinc metal is thermally sprayed on the end faces of the element while a press load is applied to form an electrode lead-out portion. Hardened. After thermal curing, leads were soldered to the end faces of the element and sealed with an epoxy resin to obtain a flat film capacitor.

(4-2) Evaluation of edge misalignment of capacitor element After slitting the metal layer integrated film obtained in the same manner as in (4-1) above using the biaxially stretched films of Examples and Comparative Examples to a width of 30 mm , two metal layer-integrated films were combined, and the metal layer-integrated film was wound using an automatic winder 3KAW-N2-60/83 type manufactured by Kaito Seisakusho. At that time, visually observe from the start of winding to the end of winding, disqualify those with misalignment of the end face, and calculate the ratio of the number of disqualified products to the total number of manufactured products (30 to 50 pieces). It was expressed as a percentage and used as an index of end face displacement. 90% or more was evaluated as “⊚”, 80% or more and less than 90% as “◯”, 70% or more and less than 80% as “Δ”, and less than 70% as “x”.

(4-3) Step boost test The capacitor obtained in (4-1) above was preheated at 120°C for 1 hour, and then the capacitance was measured with an LCR Hitester 3522-50 manufactured by Hioki Electric Co., Ltd. (initial capacitance). Next, a DC voltage of 290 V was applied to the capacitor for 1 hour in a constant temperature bath at 120°C. The capacitance of the capacitor after voltage application was similarly measured, and the rate of change in capacity before and after the test was calculated by the following formula.
(Change rate of capacitance) = [(capacitance after voltage application) - (initial capacitance)] / (initial capacitance) x 100 (%)

Then, the capacitor was put back into the constant temperature bath, the voltage was increased by 50 V, and the capacitance change rate was measured repeatedly. The test was conducted using 6 capacitors, and the number of capacitors whose rate of change in capacitance reached -90% or less was evaluated. Capacitors in which short-circuit failure occurred before the rate of capacitance change reached -90% or less and insulation was no longer maintained were regarded as defective, and subsequent tests were not conducted.

A short-circuit failure is determined when the resistance value of the capacitor is 10 kΩ or less. A super megohmmeter DSM-8104 manufactured by Hioki Electric Co., Ltd. was used as a measuring device. The upper limit of the current measurement range of this device is 10 mA, and when the current value exceeds the upper limit of the measurement range at an applied voltage of 100 V, the resistance of the capacitor is set to 10 kΩ or less.

(4-4) Measuring the potential gradient when the rate of change in capacitance reaches −20% In the step-up test, the voltage at which the rate of change in capacitance first reaches −20% or less is divided by the thickness (μm) of the film, and 6 The average value of the samples was taken as the potential gradient when the rate of change in capacitance reached -20%. Note that capacitors that failed to maintain insulation due to a short circuit before the rate of capacitance change reached -20% were not included in the average value and were excluded.

(5) Measurement and evaluation results Table 2 shows the measurement results of the content of each component in the biaxially stretched films of Examples and Comparative Examples, the measurement results of the peak height Spk, and the measurement results of the average particle size of the blended inorganic particles. shown in In addition, Table 3 shows evaluation results of film-forming properties and film properties of the biaxially stretched films of Examples and Comparative Examples, and evaluation and measurement results of capacitor properties of capacitors obtained using the films.

As described above, the film contains a syndiotactic polystyrene-based resin, a polyphenylene ether-based resin, and titanium oxide particles, and the content of the syndiotactic polystyrene-based resin in the film is 50 mass. % or more, the content of the polyphenylene ether resin in the film is 10% by mass or more, and the content of the titanium oxide particles in the film is 0.55% by mass or more and 3% by mass or less. A certain film (Examples 1 to 11) can provide a capacitor with excellent safety function operability, has high dielectric breakdown strength at high temperatures, and is a film with good element winding aptitude. Do you get it.

Claims (18)

a film,
The film contains a syndiotactic polystyrene-based resin, a polyphenylene ether-based resin, and titanium oxide particles,
The content of the syndiotactic polystyrene resin in the film is 50% by mass or more,
The content of the polyphenylene ether-based resin in the film is 10% by mass or more, and the content of the titanium oxide particles in the film is 0.55% by mass or more and 3% by mass or less.
film. 2. The film according to claim 1, wherein the content of said syndiotactic polystyrene resin in said film is 50% by mass or more and 85% by mass or less. The film according to claim 1, wherein the content of the polyphenylene ether-based resin in the film is 10% by mass or more and 45% by mass or less. The film according to claim 1, comprising a styrenic thermoplastic elastomer. 5. The film according to claim 4, wherein the content of said styrenic thermoplastic elastomer in said film is 1% by mass or more and 20% by mass or less. 5. The film of claim 4, wherein said styrenic thermoplastic elastomer is styrene-ethylene-butylene-styrene block copolymer (SEBS). 2. The film of claim 1, containing an antioxidant. 8. The film according to claim 7, wherein the content of said antioxidant in said film is 0.01% by mass or more and less than 0.5% by mass. 8. The film of Claim 7, wherein said antioxidant comprises a hindered phenolic antioxidant and a phosphorous antioxidant. The film according to claim 1, wherein the titanium oxide particles have an average particle size of 0.1 µm or more and 0.25 µm or less. 2. The film according to claim 1, wherein the protruding peak height Spk on at least one surface is 0.05 [mu]m or more and 0.30 [mu]m or less. 2. The film according to claim 1, wherein the film has a heat shrinkage rate of 1% or more and 10% or less in the film-forming direction. 2. The film of claim 1, which is a biaxially oriented film. 3. The film of claim 1, which is a monolayer film. 2. The film of claim 1, having a thickness of 10 [mu]m or less. The film according to claim 1, which is for capacitors. A metal layer-integrated film comprising the film according to any one of claims 1 to 16 and a metal layer laminated on one side or both sides of the film. A metal layer integrated film comprising the film according to any one of claims 1 to 16, or the film according to any one of claims 1 to 16 and a metal layer laminated on one side or both sides of the film. Including, capacitors.