The production process for machine-grade stretch film primarily involves raw material processing, melt extrusion, cast molding, cooling and setting, traction and stretching, and winding and packaging. Because machine-grade stretch film must be compatible with the high-speed operation of automated packaging equipment, the production process imposes strict requirements regarding film thickness uniformity, tensile properties, and winding quality.
Manufacturers typically use linear low-density polyethylene (LLDPE) as the primary raw material, incorporating functional additives-such as tackifiers and antistatic agents-based on specific product performance requirements. After precise proportioning and thorough mixing, the raw materials enter a drying and conveying system, establishing a stable material foundation for subsequent extrusion processing.
The mixed plastic pellets enter the extruder, where they are melted and plasticized at high temperatures; the action of the screw ensures the formation of a homogeneous melt. Subsequently, the melt undergoes precision filtration and is extruded through a die to form a continuous film sheet. Some high-performance machine-grade stretch films utilize a multi-layer co-extrusion process, combining materials with different properties via multiple extruders to endow the film with high strength, good tack, and excellent stretchability.
Following cast molding, the film passes over cooling rolls for rapid temperature reduction, stabilizing its structure and enhancing surface flatness. A traction system then controls the film's tension, ensuring it meets the design specifications for thickness and tensile properties. Online thickness measurement equipment monitors variations in real-time, allowing for timely adjustments to production parameters to guarantee consistent product quality.
Production equipment for machine-grade stretch film includes raw material mixing units, extruders, casting dies, cooling rolls, traction units, thickness measurement systems, corona treatment equipment, winding units, and automatic packaging machinery. Among these, the extruder handles material plasticization, the casting system determines the film's forming quality, and the winding equipment influences the flatness of the master roll and the results of subsequent processing.
Once produced, the film undergoes quality inspections, including checks for thickness, tensile strength, elongation at break, self-adhesion properties, and visual appearance. Qualified products are either slit to size or packaged and shipped directly as machine-grade stretch film rolls. Advanced production processes and automated equipment controls enhance the stability of machine-grade stretch film, meeting the requirements of logistics and transportation, warehousing and packaging, and automated industrial production.