Cast film is a non stretch, non oriented flat extruded film produced by melt flow quenching. There are two methods: single-layer drooling and multi-layer co extrusion drooling. Compared with blown film, its characteristics are fast production speed, high yield, and excellent transparency, gloss, and thickness uniformity of the film.
Cast film has superior heat sealing performance and excellent transparency, and is one of the main packaging composite substrates used in the production of high-temperature steaming film, vacuum aluminum plating film, etc. The market is highly optimistic. Moreover, with the development of domestic casting film production equipment, some of its technical indicators have reached the international advanced level. Therefore, the threshold for entering the production of cast film is getting lower and lower. Because of this, some companies
compete to import casting film production lines in order to achieve a one-step solution, pursuing higher and better levels in terms of grade, while ignoring market demand and investment return rates. This approach will result in huge resource waste.
1) The domestic cast film production line can be divided into 2500mm, 3000mm, 3500mm, and 5000mm according to the film width, and can be divided into three layers, five layers, and seven layers according to the configuration of the extruder.
2) The domestic cast film production line mainly consists of five parts: extrusion part, cast part, corona discharge part, winding part, and electric control part. The mold and extrusion parts can be freely combined according to customer requirements, thus maximizing the
satisfaction of the diverse needs of a wide range of customers (markets).
3) In addition, domestically produced equipment also closely follows the international advanced level in design, such as:
A, The unique design of the back device allows for free adjustment of the extruder pressure.
B, The unique design of the screw flow channel can be applied to different materials, achieving multi-purpose use for one machine.
C, The flow channel design of the roller provides better cooling effect, more stable product quality, and higher output.
D, The production line speed of domestically produced cast film has reached a level of 160m/min to 250m/min.
4) Compared with imported equipment, domestic cast film production lines also have the characteristics of high speed, stable performance, environmental protection, and energy saving. The thickness of the product ranges from 0.017mm to 0.08mm (calculated according to international standards as 0.025mm).
Taking the widely used polypropylene cast film (CPP) as an example, CPP is a non stretch, non oriented flat extruded film produced by melt casting quenching. Compared with blown film, its characteristics are fast production speed, high yield, good film transparency, gloss, and thickness uniformity. Meanwhile, due to its flat extruded film, subsequent processes such as printing and lamination are extremely convenient, making it widely used in the packaging of textiles, flowers, food, and daily necessities.
CPP production has two methods: single-layer casting and multi-layer co extrusion casting. The single-layer film mainly requires good low-temperature heat sealing performance and flexibility of the material. Multi layer co extruded cast film can generally be divided into three layers: heat sealing layer, support layer, and corona layer. In terms of material selection, it is wider than single-layer film and can be individually selected to meet the requirements of each layer, endowing the film with different functions and uses. The heat sealing layer needs to undergo heat sealing processing, requiring the material to have a low melting point, good hot melt properties, a wide heat sealing temperature, and easy sealing; The support layer plays a supporting role in the film, increasing its stiffness; The corona layer needs to be printed or metalized, requiring moderate surface tension and strict restrictions on the addition of additives.
The casting film forming methods for other materials such as LDPE, LLDPE, mLLDPE, PA, etc. are generally similar.
