The main equipment of the stretch film is the extruder and corresponding auxiliary equipment, such as batching, compounding, feeding system, thickness measurement system and coiling system. There are two main production processes, namely casting process and blow molding process. There are advantages and disadvantages, casting thickness uniformity, transparency, equipment, grade, production must be higher than the blow molding process, but the blow molding process elongation elongation is better than the casting process, the production equipment requirements are relatively low a lot of.
Stretched film has high tensile strength, self-adhesion, high transparency, reliable cleaning performance, relative density, high toughness, easy to use, etc., with a total capacity of more than 180kt. With the ever-increasing import volume of China's packaging industry and foreign trade, the development of agricultural product winding and freshness preservation, and the popularity of stretch film for households and supermarkets, the demand for stretch film will increase in the future.
The main raw materials of the stretched film are polyvinyl chloride (PVC), low density polyethylene (PE-LD), ethylene-vinyl acetate copolymer (EVA), linear low density polyethylene (PE-LLD), polybutadiene (PB) and other viscoelastic polymers, stretch film processing using extrusion process. At present, the main domestic use of PE-LLDPE-LD, mainly composite membrane.
The maximum film width can be produced is 0.5m or 1m. According to the different width of the production line, the blow molding process generally adopts a single-layer or multi-layer co-extrusion blown film equipment; the casting process adopts the casting production line. The imported blow molding equipment is multi-layer co-extruded (generally three layers) that can produce a maximum film width of up to 2 m. China's blow molding equipment is single-layer or double-layer, and the extrusion volume is also different. For example, the production line of the die-packaging system can reduce the necking of the film and ensure the stable production of the stretch film at high speed.
