Study of extrusion process for pouch film manufacturing

In the present study, the thickness of the melt resin and the thickness deviation depending on the line speed and the discharge rate were investigated to derive stable process conditions and determine the tendencies of the extrusion coating. The adhesive strength between the aluminum foil and the cast polypropylene (CPP) film, and the electrolyte resistance depending on the kinds of melt resin, were compared and analyzed to find a melt extrusion resin appropriate for pouch film manufacturing. In the extrusion coating, the line speed and the discharge rate had a significant effect on the coating thickness and deviation, as did the extrusion coating condition. Generally used melt extrusion resins (LDPE, LLDPE, PP, and PP(GMA)) showed similar adhesive strengths. Sufficient electrolyte resistance could not be obtained when only a melt extrusion resin was used. Addition of a functional resin resulted in a satisfactory level of electrolyte resistance. In particular, when FR_C was added as a functional resin, the extrusion coating showed excellent properties, including adhesive strength of 1300 gf/15 mm and good electrolyte resistance, with about 800 gf/ 15mm of adhesive strength at 85°C after seven days.