Cast film is a non-stretched, non-oriented flat extruded film produced by melt casting and rapid quenching. It is available in two forms: single-layer casting and multi-layer co-extrusion casting. Compared with blown film, it features faster production speed, higher output, and excellent optical properties such as transparency, gloss, and thickness uniformity.

Cast film offers superior heat-sealing properties and excellent transparency, making it one of the major packaging composite substrates. It is used in the production of high-temperature retort films, vacuum metallized films, and other products, with strong market prospects. Moreover, with the development of domestic cast film production equipment, certain technical specifications have reached internationally advanced levels. As a result, the entry barrier for cast film production has become increasingly low. Consequently, some companies are rushing to import cast film production lines in pursuit of the highest possible quality standards, while neglecting market demand and return on investment. This practice will lead to significant resource waste.

Domestic cast film production lines are available in film widths of 2500mm, 3000mm, 3500mm, and 5000mm. In terms of extruder configuration, they are available in three-layer, five-layer, and seven-layer versions.

A domestic cast film production line mainly consists of five parts: the extrusion section, casting section, corona treatment section, winding section, and electrical control section. Among these, the die section and extrusion section can be flexibly combined according to customer requirements, thereby meeting the diverse needs of a wide range of clients.

In addition, domestic equipment design keeps pace with international advanced standards. For example:

A. The unique back-pressure device design allows for free adjustment of the extruder pressure.

B. The unique screw channel design enables compatibility with different materials, achieving multi-purpose functionality with a single machine.

C. The roll channel design provides better cooling effects, more stable product quality, and higher output.

D. The line speed of domestic cast film production lines has reached 160–250 m/min.

Compared with imported equipment, domestic cast film production lines offer comparable high speed, stable performance, environmental protection, and energy efficiency. The product thickness ranges from 0.017 mm to 0.08 mm (calculated at the international standard thickness of 0.025 mm).

Taking the most widely used polypropylene cast film (CPP) as an example, CPP is a non-stretched, non-oriented flat extruded film produced by melt casting and rapid quenching. Compared with blown film, it features faster production speed, higher output, and excellent transparency, gloss, and thickness uniformity. In addition, as a flat extruded film, downstream processes such as printing and lamination are extremely convenient, making it widely used in packaging for textiles, flowers, food, and daily necessities.

CPP production is available in two forms: single-layer casting and multi-layer co-extrusion casting. Single-layer film primarily requires low-temperature heat-sealing properties and good flexibility. Multi-layer co-extrusion cast film is generally composed of three layers: a heat-seal layer, a support layer, and a corona treatment layer. The material selection for multi-layer films is broader than for single-layer films, allowing separate selection of materials that meet the requirements of each specific layer, thereby imparting different functions and applications to the film. Among these, the heat-seal layer is subject to heat-sealing processing and requires a lower melting point, good hot-melt properties, a broad heat-sealing temperature range, and easy sealing. The support layer provides structural support to the film and increases its stiffness. The corona treatment layer is intended for printing or metallization, requiring moderate surface tension and strict limitations on additive content.

The cast film forming methods for other materials such as LDPE, LLDPE, mLLDPE, and PA are largely similar to the process described above.