METHOD OF PRODUCING PROPYLENE RESIN MICROPOROUS FILM, PROPYLENE RESIN MICROPOROUS FILM, SEPARATOR FOR LITHIUM-ION CELL, AND LITHIUM-ION CELL

摘要

PROBLEM TO BE SOLVED: To provide a method of producing a propylene resin microporous film, by which: a high-end lithium-ion cell can be manufactured which is excellent in lithium-ion permeability; and short-circuiting between a positive electrode and a negative electrode can be prevented from occurring due to dendrite.

SOLUTION: The method of producing the propylene resin microporous film includes: a first cooling step of cooling a propylene resin film extruded from a lower die at equal to or lower than a temperature lower by 60 to 1°C than the melting point of the propylene resin; a masking step of masking the propylene resin film obtained after the first cooling step for ≥1 minute at a temperature lower by 100 to 5°C than the melting point of the propylene resin; a second cooling step of cooling the propylene resin film obtained after the masking step until the surface of the propylene resin film is cooled to less than a temperature lower by 100°C than the melting point of the propylene resin; an extension step of uniaxially extending the propylene resin film obtained after the second cooling step; and an annealing step of annealing the propylene resin film obtained after the extension step.

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