The main processing methods of TPU films today include blown film, cast, coated, and calendered methods. Among them, the blown film method and cast method are the most popular ones for processing TPU films.
Blown film method
The film has high ductility and elasticity, so it is more complicated in the process of blown film processing and difficult to process by forming alone. Therefore, the general process is through the easy-to-form PE for seat liner co-extrusion molding process. In other words, the TPU raw material and PE raw material are plasticized and extruded by different extruders, and then compounded in the co-extruded film tool, and the PE layer is peeled off for recycling when used.
Casting method
The raw material is plasticized and melted by the extruder. The film is cooled down and shaped on the cooling roller, and then the product is wound up after traction and edge cutting.
Coating Method
TPU extrusion coating is the production process of pasting molten TPU onto the substrate.TPU resin is extruded from the extruder feed tube, and the substrate is pulled between the molten material and the rubber pressurized leather, and extruded between two wheels through the flat die head. The pressure of the pressurized rollers is adjusted to laminate the plasticized TPU material onto the substrate, and the hot adhesive tape is cooled through a metal stick, the edges are cut and wrapped together for a one-time processing and molding application.
Processing characteristics of TPU film
TPU resin is highly hygroscopic. Too much moisture in the granular material will cause processing problems and the quality of the finished product will deteriorate. Therefore, both TPU material and processing aids should be dried before processing. The moisture content of the granular material after drying should not exceed 0.02% (weight percentage). The dried resin should be stored immediately in a dry container that can be safely sealed to avoid moisture absorption again. Generally speaking, if the TPU film has foaming phenomenon or foam after plasticization, it means the drying effect is not good.
The TPU particle resin has high density, elasticity, and has higher temperature characteristics after drying. The resin is easy to bridge on the ordinary hopper, so the blanking area of the hopper and the barrel should be specially designed. Taking into account the high price of TPU resin, the configuration of the metering supply system can effectively save the consumption of raw materials.
