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WO-2026095049-A1 - STRETCHED FILM, METAL LAMINATED FILM, AND FILM CAPACITOR

WO2026095049A1WO 2026095049 A1WO2026095049 A1WO 2026095049A1WO-2026095049-A1

Abstract

The purpose of the present invention is to provide a stretched film capable of imparting excellent safety performance to a capacitor element even under a high temperature environment.　In a stretched film according to the present invention, calculated in a 145°C environment from formula (1) ρ V145°C = (SxV)/(DxA 1 ) (1), a volume resistivity ρ V145°C is 8.0x10 14 Ω•cm or greater, or ρ V145°C /ρ V40°C is 0.05 or greater (where in formula (1), ρ V145°C is volume resistivity (Ω•cm) in a 145°C environment, S is an effective electrode area (cm 2 ), V is an applied voltage (V), D is the thickness (cm) of the stretched film, and A 1 is the detected value of the current value one minute after a voltage with a potential gradient of 100 V/µm is applied to the stretched film in a 145°C environment.

Inventors

  • NAKAMURA, Toko
  • ISHIWATA, TADAKAZU
  • SUEI, Takumi

Assignees

  • 王子ホールディングス株式会社

Dates

Publication Date
20260507
Application Date
20251031
Priority Date
20241031

Claims (16)

  1. A stretched film containing a polypropylene resin, The following formula (I) ρ V145℃ = (S×V)/(D×A 1 ) (I) (In equation (I), ρ V145℃ is the volume resistivity (Ω·cm) at a 145℃ environment, S is the effective electrode area ( cm² ), V is the applied voltage (V), D is the thickness of the stretched film (cm), and A1 is the detected current value 1 minute after applying a voltage with a potential gradient of 100 V/μm to the stretched film at a 145℃ environment.) A stretched film having a volume resistivity ρ V145℃ of 8.0 × 10¹⁴ Ω·cm or higher, calculated from the above.
  2. A stretched film containing a polypropylene resin, The following formula (I) ρ V145℃ = (S×V)/(D×A 1 ) (I) (In equation (I), ρ V145℃ is the volume resistivity (Ω·cm) at a 145℃ environment, S is the effective electrode area ( cm² ), V is the applied voltage (V), D is the thickness of the stretched film (cm), and A1 is the current value 1 minute after applying a voltage with a potential gradient of 100 V/μm to the stretched film at a 145℃ environment.) The volume resistivity ρ V145℃ calculated from the environment at 145℃, The following equation (II) ρ V40℃ = (S×V)/(D×A 2 ) (II) (In equation (II), ρ V40℃ is the volume resistivity (Ω·cm) at a 40℃ environment, S is the effective electrode area ( cm² ), V is the applied voltage (V), D is the thickness of the stretched film (cm), and A² is the detected current value 1 minute after applying a voltage with a potential gradient of 100 V/μm to the stretched film at a 40℃ environment.) The volume resistivity ρ V40℃ calculated from the above, A stretched film in which the ratio (ρ V145℃ / ρ V40℃ ) is 0.05 or greater.
  3. The stretched film according to claim 1 or 2, wherein the height Spk of the protruding peaks on at least one surface is 0.01 μm or more and 0.15 μm or less.
  4. The stretched film according to claim 1 or 2, wherein the arithmetic mean height Sa of at least one surface is 0.008 μm or more and 0.050 μm or less.
  5. The stretched film according to claim 1 or 2, wherein the depth Svk of the protruding valleys on at least one surface is 0.01 μm or more and 0.06 μm or less.
  6. The stretched film according to claim 1 or 2, wherein, in X-ray diffraction intensity measurement, the crystallite size determined by Scherrer's formula based on the half-width of the (110) plane originating from the α-crystal of isotactic polypropylene is 105 Å or greater, and the ratio of the crystallite size of the (110) plane to the crystallite size of the (040) plane, "(110 plane) crystallite size / (040 plane) crystallite size," is 1.0 or greater.
  7. The stretched film according to claim 1 or 2, wherein, in infrared absorption spectral measurement, it has at least one of an absorption peak in the range of 880 to 890 cm⁻¹ and an absorption-induced shoulder peak around 1450 cm⁻¹ .
  8. The aforementioned polypropylene resin is An isotactic polypropylene resin comprising 55% by mass or more and 99% by mass or less, A stretched film according to claim 1 or 2, comprising 1% by mass or more and 45% by mass or less of a polymer having an alicyclic structure.
  9. The stretched film according to claim 8, wherein the polymer having the alicyclic structure comprises two or more polymers with different glass transition temperatures.
  10. The stretched film according to claim 8, wherein the polymer having an alicyclic structure comprises polymer B1 having an alicyclic structure with a glass transition temperature of 133°C to 155°C, and polymer B2 having an alicyclic structure with a glass transition temperature of 70°C to less than 133°C.
  11. The stretched film according to claim 10, wherein the mass ratio B2/B1 of polymer B2 to polymer B1 is less than 0.85.
  12. The stretched film according to claim 8, wherein the polymer having the alicyclic structure contains hydrogenated polystyrene.
  13. The aforementioned hydride polystyrene has an atactic structure, The stretched film according to claim 12, having a hydrogenation rate of 95% or more.
  14. A stretched film according to claim 1 or 2, having a thickness of 1.8 μm or more and 10 μm or less, and a total light transmittance of 80% or more.
  15. A metal laminated film having a metal layer on one or both sides of the stretched film according to claim 1 or 2.
  16. A film capacitor comprising the metal laminated film described in claim 15.

Description

Stretched films, metal laminated films, and film capacitors This invention relates to a stretched film formed from a polypropylene resin, a metal laminated film having the stretched film, and a film capacitor. Stretched films primarily composed of polypropylene are used in film capacitor applications due to their excellent electrical properties. In electronic and electrical equipment, film capacitors made from stretched polypropylene are used, for example, as high-voltage capacitors, various switching power supplies, filter capacitors in converters and inverters, and smoothing capacitors. Film capacitors are also increasingly used in automobiles, such as electric vehicles and hybrid vehicles, where demand has been growing in recent years, for example, in inverters and converters that control drive motors. Film capacitors, particularly automotive film capacitors, are increasingly being used in high-temperature environments. For example, in devices that control automotive drive motors (inverters, converters, etc.), the use of highly heat-resistant semiconductors (such as silicon carbide semiconductors) has increased in recent years. Consequently, capacitors used in these devices require high heat resistance, such as 120°C or higher, preferably 130°C or higher. Conventional polypropylene film capacitors have an upper temperature limit of approximately 110°C, making it extremely difficult to maintain stable electrical insulation in high-temperature environments exceeding this limit. As one example of a resin film with high heat resistance, a film is disclosed that exhibits excellent heat resistance, and particularly excellent water vapor impermeability, and is made of a resin composition containing a polyolefin mainly composed of polypropylene and a hydrogenated block copolymer (Patent Document 1). The results of the infrared absorption spectra of the stretched film are shown, with (a) showing the range of 850 to 950 cm⁻¹ in the infrared absorption spectrum measurement, and (b) showing the range of 1400 to 1500 cm⁻¹ . The embodiments of the present invention will be described in detail below. In this specification, the expressions "containing" and "including" encompass the concepts of "containing," "including," "substantially consisting of," and "consisting solely of." In the numerical ranges described stepwise in this specification, the upper or lower limit of a numerical range in one step can be arbitrarily combined with the upper or lower limit of a numerical range in another step. In the numerical ranges described in this specification, the upper or lower limit of that range may be replaced with values shown in the examples or values that can be uniquely derived from the examples. Furthermore, in this specification, numbers enclosed in "~" signify a numerical range that includes the numbers before and after "~" as the lower and upper limits. 1. Stretched Film The stretched film of the present invention includes the following stretched film A and stretched film B. Stretched film A: The following formula (I) ρ V145℃ = (S×V)/(D×A 1 ) (I) (In equation (I), ρ V145℃ is the volume resistivity (Ω·cm) at a 145℃ environment, S is the effective electrode area ( cm² ), V is the applied voltage (V), D is the thickness of the stretched film (cm), and A1 is the detected current value 1 minute after applying a voltage with a potential gradient of 100 V/μm to the stretched film at a 145℃ environment.) The volume resistivity ρ V145℃ calculated from this is 8.0 × 10¹⁴ Ω·cm or higher in a 145℃ environment. Stretched film B: The following formula (I) ρ V145℃ = (S×V)/(D×A 1 ) (I) (In equation (I), ρ V145℃ is the volume resistivity (Ω·cm) at a 145℃ environment, S is the effective electrode area ( cm² ), V is the applied voltage (V), D is the thickness of the stretched film (cm), and A1 is the detected current value 1 minute after applying a voltage with a potential gradient of 100 V/μm to the stretched film at a 145℃ environment.) The volume resistivity ρ V145℃ calculated from the environment at 145℃, The following equation (II) ρ V40℃ = (S×V)/(D×A 2 ) (II) (In equation (I), ρ V40℃ is the volume resistivity (Ω·cm) at a 40℃ environment, S is the effective electrode area ( cm² ), V is the applied voltage (V), D is the thickness of the stretched film (cm), and A² is the detected current value 1 minute after applying a voltage with a potential gradient of 100 V/μm to the stretched film at a 40℃ environment.) The volume resistivity ρ V40℃ calculated from the above, The ratio (ρ V145℃ / ρ V40℃ ) is 0.05 or greater. The stretched film A and the stretched film B of the present invention have high insulation resistance values in high-temperature environments, and can provide excellent safety performance to capacitor elements even in high-temperature environments. For example, they can provide excellent safety performance to capacitor elements even in an environment of 135°C. Furthermore, The stretched film A of the present invention has a