Exploring the production process and flow of plastic packaging film

In the field of modern commodity circulation, plastic packaging film has become an indispensable packaging material with its excellent protection and display functions. Its transformation from raw materials to finished products embodies a complex and exquisite production process, and each link determines the final performance and quality of the packaging film.

The first link in the production of plastic packaging film is raw material selection and pretreatment. According to different usage requirements, common raw materials include polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), etc. For example, food packaging film mostly uses non-toxic and odorless polyethylene because of its good chemical stability and hygienic safety; while packaging film for industrial use may use polyvinyl chloride to obtain better mechanical strength and weather resistance. After selecting the raw materials, they need to be dried to remove moisture and impurities to prevent defects such as bubbles and cracks in subsequent processing, which will affect the quality of the packaging film.

After the raw materials are ready, the core molding process stage is entered. Blow molding is one of the most commonly used methods. Its principle is to extrude the heated molten plastic raw material into a tube billet through an extruder, and then pass compressed air into the tube billet to make it inflated like a balloon. Under the action of the cooling air ring, it quickly cools and shapes to form a tubular film. This process can produce packaging films of different thicknesses and widths, with high production efficiency and continuous operation. Casting is suitable for the production of packaging films with extremely high requirements for flatness and thickness accuracy. This process extrudes the molten plastic through a slit die head and directly casts it onto a cooling roller, which is quickly cooled and solidified into a film. The packaging film produced by cast molding has uniform thickness and high transparency, and is often used for packaging high-end electronic products and optical materials. In addition, calendering is also common. It is to pass the heated plasticized plastic raw material through a series of roller gaps rotating in opposite directions to extend it into a film of specified thickness and width. This process is suitable for the production of thermoplastic plastic packaging films such as polyvinyl chloride, which can give the packaging film good surface finish and hardness.

The formed plastic packaging film also needs to be processed to meet different usage requirements. Printing is a common post-processing process. Through gravure printing, flexographic printing and other technologies, product information, patterns and logos are printed on the surface of the packaging film to enhance the recognition and aesthetics of the product. Before printing, the packaging film is usually subjected to corona treatment to increase its surface tension, improve the adhesion of the ink, and ensure that the printed pattern is clear and durable. In addition, in order to enhance the barrier properties of the packaging film and extend the shelf life of the product, coating or lamination processes are used. Coating is to apply a layer of material with special functions on the surface of the packaging film, such as barrier coating, antistatic coating, etc.; lamination is to combine two or more films with different properties by adhesives or hot pressing, so that the packaging film has a variety of excellent properties, such as moisture-proof, anti-oxidation, puncture resistance, etc.

Finally, the finished packaging film must undergo strict quality inspection. The inspection items include thickness uniformity, tensile strength, elongation at break, light transmittance, heat sealing performance, etc. Through professional testing equipment and methods, the physical and chemical properties of the packaging film are comprehensively evaluated. Only products that meet quality standards can enter the market and provide reliable packaging protection for the goods.

From raw materials to finished products, every step of the production process of plastic packaging film is closely linked. The sophisticated process and advanced technology ensure the efficient application of packaging film in various fields. With the development of science and technology, the production process is also constantly innovating, moving towards more energy-saving, more environmentally friendly, and higher performance, and continuously meeting the increasingly diverse needs of the market.