Extrusion is one of the most common methods for producing PET sheets. First, PET resin pellets are added to the extruder and melted under high temperatures and pressure. Then, the molten PET resin is extruded into sheets through a mold, and after cooling, stretching, and other processes, PET sheets are finally obtained. During the extrusion process, control of parameters such as temperature, pressure, and extrusion speed is critical, and they will directly affect the quality and performance of the PET sheet. For example, if the temperature is too high, the PET resin may degrade, affecting the performance of the sheet; if the temperature is too low, the fluidity of the PET resin deteriorates, which may cause uneven thickness of the sheet.
Calendering is also a commonly used production process. After the PET resin is heated to a molten state, it is extruded and stretched through the rollers of the calendar to form a sheet. The PET sheets produced by the calendering method have high surface flatness and good thickness uniformity, but the production efficiency is relatively low and the equipment investment is large. This process is often used to produce PET sheets with high requirements for surface quality and thickness uniformity, such as insulating sheets in the electronics industry.
Injection molding is mainly used to produce PET sheet products, such as PET plastic bottles. The molten PET resin is injected into the mold, and the product is obtained after cooling and solidification. The products produced by injection molding are high in precision and can produce products with complex shapes, but the cost of sheet production is high, and the size of the sheet is limited by the mold. However, in some special application scenarios, injection molding can produce PET sheet products with special structures or functions.