Cast film is a kind of non stretching and non oriented flat extruded film produced by melt salivation quenching. There are two ways: monolayer salivation and multi-layer co extrusion salivation. Compared with blown film, it is characterized by fast production speed, high output, excellent transparency, luster, thickness uniformity, etc.
Cast film has excellent heat sealing performance and excellent transparency. It is one of the main packaging composite substrates. It is used to produce high-temperature cooking film, vacuum aluminum coating film, etc. The market is very promising. Moreover, with the development of domestic tape casting film production equipment, some of the technical indicators have reached the international advanced level. As a result, the threshold for entering the tape casting film production is getting lower and lower. Because of this, some enterprises compete to import cast film production lines in order to reach the goal in one step, and the higher the level, the better, while leaving market demand and return on investment aside, which will cause huge waste of resources.
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 tape casting film production line is mainly composed of five parts: extrusion part, tape casting part, corona part, winding part and electric control part. The mold part and extrusion part can be combined freely according to the requirements of customers, so as to meet the different needs of customers (markets) to the greatest extent.
3) In addition, the design of domestic equipment also follows the international advanced level, such as:
A. The unique design of the back device can freely adjust the pressure of the extruder.
B. The unique design of screw runner can be applied to different materials to achieve multiple purposes.
C. The runner design of the roller has better cooling effect, more stable product quality and higher output.
D. The line speed of domestic tape casting film production line has reached the level of 160m/min – 250m/min.
4) Compared with the imported equipment, the domestic tape casting film production line also has the characteristics of high speed, stable performance, environmental protection and energy conservation. The product thickness is 0.017mm-0.08mm (international standard is 0.025mm).
Take PP tape casting film (CPP), which is the most widely used film, as an example. CPP is a non stretching and non oriented flat extruded film produced by melt casting quenching. Compared with blown film, it is characterized by fast production speed, high output, good transparency, luster and thickness uniformity of the film. At the same time, due to the flat extrusion film, the subsequent processes such as printing and lamination are extremely convenient, so it is widely used in the packaging of textiles, flowers, food and daily necessities.
CPP can be produced by single-layer tape casting and multi-layer co extrusion tape casting. Single layer film mainly requires good low-temperature heat sealing performance and flexibility of materials. Multilayer co extruded cast film can generally be divided into three layers: heat seal layer, support layer and corona layer. The selection of materials is wider than that of single layer film. Materials that meet the requirements of each layer can be selected separately, giving the film different functions and uses. The heat sealing layer shall be heat sealed. The melting point of the material shall be low, the hot melting property shall be good, the heat sealing temperature shall be wide, and the sealing shall be easy; The support layer supports the film and increases the stiffness of the film; The corona layer shall be printed or metallized, with moderate surface tension and strict restrictions on additives.
The tape casting film forming methods of other materials, such as LDPE, LLDPE, mLLDPE, PA, are similar to this.