Sagging evaluation method for microporous membrane

摘要

PROBLEM TO BE SOLVED: To provide a microporous membrane slack evaluation method suited for inspections of all products and capable of reducing measurement errors while eliminating waste that occurs at a time of evaluating the slack of a microporous membrane.SOLUTION: A microporous membrane slack evaluation method comprises: calculating a cross-sectional shape of a wound body by calculation using outside diameter values of a plurality of portions of the wound body; dividing an outside diameter shape of the wound body into a plurality of disc-like micro areas 4 each having a very small thickness; approximating and modeling the outside diameter shape of the wound body by a mathematical model that is a combination of these micro areas 4; representing a relation between a tensile force f and a strain &Dgr;I/I acting on the micro areas 4 by a mathematical formula if it is simulated that a microporous membrane is unwound from the wound body; combining the relation between the tension f and an extension &Dgr;I represented by the mathematical formula with the model that is the combination of the micro areas 4; comparing unwind amounts of the two adjacent micro areas 4; calculating an inter-area slack amount that occurs between the micro areas 4; integrating the inter-area slack amounts for the entire areas 4, and calculating a slack shape of the microporous membrane over an entire width.