| 摘要 |
PROBLEM TO BE SOLVED: To allow quality of a film roll of a stretched film or the like to be determined before processing into a film, so that quality defects of film products using the film roll can be improved.SOLUTION: A film roll quality determination method includes: (A) putting a needle 3 into a surface of a film roll 1R to form measurement holes 4 in a center part and both end parts in a breadthwise direction; (B) feeding a film 1 to pick up a strip-shaped measurement film 1M having measurement holes at both ends in a flow direction with respect to each measurement hole in the breadthwise direction; (C) measuring a length L between measurement holes in the flow direction in each measurement film; and (D1) calculating a variation index Df={(Lmax-Lmin)/Lmin}×1000 from a maximum value Lmax and a minimum value Lmin of the length L and determining the film roll to be satisfactory in the case of the variation index Df being equal to or lower than a decision criterion Sf and determining the film roll to be defective in the case of the variation index Df being higher than the decision criterion. Further, the method may include (D2) evaluating a variation coefficient Dg as a degree of change in the breadthwise direction of a variation d by a decision criterion Sg. |
