SEALING DEFECT DETECTION METHOD FOR RETORT POUCH PACKING MATERIAL AND APPARATUS

PURPOSE:To provide the detective method and its apparatus by which sealing defects of the heat-sealing part of a retort pouch-packing material can be effectively detected. CONSTITUTION:An electric conductive layer forces the heat-sealed part of a retort pouch-packing material electrically connected with an earthing electrode to pass into the groove of a sensor 11 and the distances L1, L2 between respective probes 13, 14 and the electric conductive layer are measured basing on the electrostatic capacity between the respective probes 13, 14 and the electric conductive layer. Gross thickness (t) between respective electric conductive layers including polypropylene forming the heat-sealed part in the retort pouch- packing material is calculated from these distances L1, L2 and the width (p) between respective probes 13, 14. And the sealing defects are detected basing on the calculated gross thickness (t). Since the gross thickness (t) becomes large at the point of sealing defect, it can be detected.