SEAL-THROUGH-CONTAMINATION AND 'CAULKABILITY' AN EVALUATION OF SEALANTS' ABILITY TO ENCAPSULATE CONTAMINANTS IN THE SEAL AREA

摘要

Channel leaks are a recurring problem in flexible packaging that lead to product waste and premature spoilage. A common cause of channel leaks is product contamination in the seals. If the sealant fails to flow around or fully encapsulate a solid contaminant in the seal, an air channel may form through the seal resulting in package integrity loss. A perceived strategy for minimizing contaminant-channel leakers is to choose sealants with better "caulkability" or seal-through-contamination ability. While these concepts seem intuitive, there is no consensus on what fundamental properties makes a sealant "caulkable" and no standard test for quantifying this attribute. The purpose of this study was to evaluate the ability of various sealants to encapsulate contaminants and minimize the channel or void area around a contaminant. A practical test was developed to measure a sealant's ability to encapsulate a simulated contaminate in multilayer, heat-sealed films. The results suggest that sealants with the optimal combination of zero shear viscosity (ZSV), hot tack strength window (HTS) and other sealant properties are required to fully encapsulate seal area contaminants. The optimal combination depends on the contaminate size, converting conditions and multilayer film structure.