Biaxially oriented polypropylene film for capacitor, metal laminated film, and film capacitor

Abstract

A biaxially oriented polypropylene film for a capacitor, in which mu dm and mu dt are each in the range of 0.60-1.70 and the value of the ratio (mu dm/mu dt) of mu dm and mu dt is 0.75 to less than 1.15, where mu dm is the kinetic friction coefficient in a longitudinal direction and mu dt is the kinetic friction coefficient in a width direction, and the film thickness measured by a micrometer method is in the range of 0.5-3 mum. Provided is a biaxially oriented polypropylene film for a capacitor, whereby excellent withstand voltage is demonstrated in a capacitor application, and stable productivity and workability are ensured.

Description

technical field [0001] The present invention relates to a biaxially oriented polypropylene film suitable for industrial use, etc., and more specifically, to a biaxially oriented polypropylene film for capacitors which maintains stable In addition to high transportability, it is excellent in productivity and processability. Background technique [0002] Biaxially oriented polypropylene films are used in various applications such as packaging applications, tape applications, and electrical applications represented by cable sheathing and capacitors due to their excellent transparency, mechanical properties, and electrical properties. [0003] Among them, for capacitor applications, due to its excellent withstand voltage characteristics and low loss characteristics, it is particularly suitable for use in high-voltage capacitors, and is not limited by DC applications and AC applications. [0004] Recently, various electric devices have been converted into inverters, and accordin...

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Problems solved by technology

[0007] However, mechanical and chemical methods have a low roughness density, and in the method of orienting the β-crystal-forming sheet, coarse protrusions are likely to occur, and especially from the viewpoint of processability, there is a problem with film slipperiness. say it must be sufficient

In addition, for the film roughened by these methods, when making a capacitor, the film handling property is poor, the winding property is poor, and it is difficult to make the air volume between the film layers appropriate, especially for oil-impregnated capacitors. In some cases, oil impregnation becomes insufficient, and unimpregnated parts tend to be partially formed, and the life of the capacitor may be reduced.

[0008] In addition, under the condition of strict cost reduction in terms of processability and productivity of capacitors, the biaxially oriented polypropylene film produced by any of the above-mentioned methods has the following problems. question

In addition, when the surface is roughened to impart slidability, coarse protrusions formed on the surface by adding external particles, falling off of external particles, etc. are the main factors that significantly reduce the voltage resistance of the capacitor, and it cannot be said that it is always satisfactory.

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