Priehľadná stena letiska
The production process of PC sheet is extrusion molding, and the main equipment required is an extruder. Because the processing of PC resin is difficult, the requirements for production equipment are high. Most of the equipment for domestic production of PC boards is imported, most of which comes from Italy, Germany and Japan. Most of the resins used are imported from GE in USA and Baver in Germany. Before extrusion, the material should be strictly dried so that its moisture content is below 0.02% (mass fraction). The extrusion equipment should be equipped with vacuum drying hoppers, sometimes several are needed in series. The body temperature of the extruder should be controlled at 230-350°C, gradually increasing from back to front. The head used is a flat extruded slit type head. The extrusion is then cooled by calendering. In recent years, in order to meet the requirements of the PC board anti-UV performance, often in the PC board surface covered with a thin layer of anti-UV (UV) additives, which requires a two-layer co-extrusion process, that is, the surface layer contains UV additives and the bottom layer does not contain UV additives. These two layers are laminated in the head and extruded into one. This kind of head design is more complicated. Some companies have adopted some new technologies, such as Bayer's co-extrusion system with a specially designed melt pump and merging device and other technologies. In addition, there are some occasions that require PC boards to be drip-free, so there should be an anti-drip coating on the other side. There are also PC boards that need to have anti-UV layer on both sides, and the production process of such PC boards is more complicated.
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