Blow molding is a plastic processing technique that involves heating plastic pellets to melt them and then blowing them into a thin film. Typically, it uses a polymer extrusion process to form a tubular blank, which is then inflated to the desired thickness using high-pressure air while in a good melt flow state. After cooling and shaping, it becomes a film.
The quality of the film material blown by this processing technology is related to the blowing machine and plastic pellets. The production equipment is simple, with low investment and rapid product effectiveness; the film has high mechanical properties; there is little waste material; the film products are cylindrical, with a simple bag-making process; and it can produce wide-width film.
If the film is blown with new material, it has an even color, is clean, and has good stretch in the finished product. If plastic pellets made from recycled waste plastic are used, it usually requires the addition of colorant during the film production process. The resulting film may have uneven coloring, be brittle, and prone to breakage, and it will also be priced lower.
Blown film materials produced by professional blowing machines are suitable for various high-quality film packaging. This film, due to its excellent barrier properties, preservability, moisture and frost resistance, oxygen barrier, and oil resistance, can be widely used in both light and heavy packaging. This includes various fresh fruits, meat products, pickled vegetables, fresh milk, liquid beverages, and more. If non-professional blowing machines are used or incorrect methods are employed during the processing, the resulting film material may be of inferior quality.
Most PE is used for blowing film processing, and both general low-density PE (LDPE) and linear low-density PE (LLDPE) are available. HDPE film grade is typically used where high tensile and barrier properties are required. For example, HDPE films are commonly used for product bags, grocery bags, and food packaging. PE film processing usually employs either standard blowing film or flat extrusion methods.
