Comparison of Film Blowing and Casting Methods

Comparison of Film Blowing and Casting Methods

1. The casting method is more suitable for multi-layer co-extrusion film production and processing than the blow molding method. Especially when a variety of materials of different materials are used for co-extrusion, the production process parameters of the casting method are easier to control, and the processing equipment The key part - the design of the die head can effectively ensure the uniformity of distribution of various materials in the product. The multi-layer co-extrusion die of the blow molding method is more technically difficult, the structure is more complex and the technology is not yet mature enough.

2. In the processing equipment of the tape casting method, the distance from the die to the cold roller (from forming to setting) is generally 10 to 20 mm. The melting film curtain is very short and can be easily processed with the help of a vacuum suction hood, an air knife and an edge fixing device. Quick finalization, product quality is good and stable. The blow molding method has a blowing process due to the melted film and relies on air or water to cool and shape. The setting time of the product is too long and the product changes greatly before setting (generally inflated 4 to 7 times). It is easy to be affected by external and internal factors during the melting film stage. Product quality control is very difficult and has poor stability.

3. There is also a big difference between the blow molding method and the casting method in the selection of raw materials. When multi-layer co-extrusion, the blow molding method requires the use of materials with close fluidity to match each other. When the fluidity of the materials is greatly different, there is no corresponding response. Therefore, when one of the materials is selected, there is not much choice for other materials co-extruded with it, which to a great extent restricts the embodiment of the advantages of multi-layer co-extrusion processing technology in product quality, and The processing equipment of the tape casting method can easily solve the almost unsolvable problems in the blow molding method by adjusting the split channel.