Blown Film Extrusion Process for Polybags: Technical Overview and Applications

Abstract

The choice of extrusion process is a decisive factor that affects the finished product quality for polybag manufacturing. One important component influencing the quality of the finished product is the selection of the extrusion technique. Two popular procedures that vary in the kind of dye used and the final product’s texture are cast film and blown film. In the horizontal extrusion moulding method known as “cast film”, heated resin is injected into a flat dye and allowed to cool on chill rolls. The film produced is clear, lightweight, and appropriate for lamination; its thickness varies based on the winding speed and the film is slower to crystallize and has less clarity but more durability because the resin molecules have reoriented, facing limitation of high wastage generation. This study primarily focused on the preparation of polybag film using the blown film extrusion process, utilizing high-quality polymer resins such as polyester polyethylene (PP) and linear low-density polyethylene (LLDPE) to minimize waste generation. The novelty of the process was reflected in minimising the waste generation. The control parameters considered in this study are temperature, pressure, and air intake volume. We investigated the influence of these critical process control parameters on the gauge thickness, optical properties, and mechanical strength of the polybag film produced through blown film extrusion. Additionally, we replicated the blown film process using simulation software developed at Pennsylvania College of Technology. The simulation results confirmed the overall stability of the polybag film produced through the blown film extrusion process.