Abstract: In regard to at least one of long separator sheets (12a, 12b), measurement is carried out to measure the amount of curl at an edge of the at least one of the long separator sheets (12a, 12b) while applying tension to the at least one of the long separator sheets (12a, 12b) in the lengthwise direction (MD) of the at least one of the long separator sheets (12a, 12b), the edge being parallel to the lengthwise direction (MD) of the at least one of the long separator sheets (12a, 12b). This makes it possible to provide a method of measuring the amount of curl in a separator, a slitting apparatus, and a curl amount measuring apparatus, each of which is capable of carrying out a highly accurate nondestructive measurement of the amount of curl without having to cut a sample from a long separator sheet.

Abstract: A core (u1, u2) around which a nonaqueous electrolyte secondary battery separator is to be wound. A side surface of the core (u1, u2) has a depression (20). This makes it possible, in a case where cores (separator cores) are stored by being stacked while still wet after cleaning, to prevent damage to a core caused by a problem where cores stick together and an core lower in a stack falls when a core higher in the stack is removed.

Abstract: A core (u1, u2) around which a nonaqueous electrolyte secondary battery separator is to be wound. A side surface of the core (u1, u2) has a depression (20). This makes it possible, in a case where cores (separator cores) are stored by being stacked while still wet after cleaning, to prevent damage to a core caused by a problem where cores stick together and an core lower in a stack falls when a core higher in the stack is removed.

Abstract: In regard to at least one of long separator sheets (12a, 12b), measurement is carried out to measure the amount of curl at an edge of the at least one of the long separator sheets (12a, 12b) while applying tension to the at least one of the long separator sheets (12a, 12b) in the lengthwise direction (MD) of the at least one of the long separator sheets (12a, 12b), the edge being parallel to the lengthwise direction (MD) of the at least one of the long separator sheets (12a, 12b). This makes it possible to provide a method of measuring the amount of curl in a separator, a slitting apparatus, and a curl amount measuring apparatus, each of which is capable of carrying out a highly accurate nondestructive measurement of the amount of curl without having to cut a sample from a long separator sheet.

Abstract: A core (u1, u2) around which a nonaqueous electrolyte secondary battery separator is to be wound. A side surface of the core (u1, u2) has a depression (20). This makes it possible, in a case where cores (separator cores) are stored by being stacked while still wet after cleaning, to prevent damage to a core caused by a problem where cores stick together and an core lower in a stack falls when a core higher in the stack is removed.

Abstract: A core (u1, u2) around which a nonaqueous electrolyte secondary battery separator is to be wound. A side surface of the core (u1, u2) has a depression (20). This makes it possible, in a case where cores (separator cores) are stored by being stacked while still wet after cleaning, to prevent damage to a core caused by a problem where cores stick together and an core lower in a stack falls when a core higher in the stack is removed.

Abstract: Provided is a porous film obtained by melt-kneading a high-molecular-weight polyolefin having a weight-average molecular weight of not less than 5×105, a thermoplastic resin having a weight-average molecular weight of not more than 2×104 and fine particles, molding the kneaded matter into a sheet, and then stretching the sheet. The porous film can be easily and simply prepared, and has a high piercing strength, and hence can be advantageously used as a separator for a battery, particularly for a lithium secondary battery.

Abstract: Provided is a porous film obtained by melt-kneading a high-molecular-weight polyolefin having a weight-average molecular weight of not less than 5×105, a thermoplastic resin having a weight-average molecular weight of not more than 2×104 and fine particles, molding the kneaded matter into a sheet, and then stretching the sheet. The porous film can be easily and simply prepared, and has a high piercing strength, and hence can be advantageously used as a separator for a battery, particularly for a lithium secondary battery.