How to set the temperature and timing of PET crystallization drying?
🌟PET is a milky white or light yellow highly crystalline polymer with a smooth and shiny surface. Due to its properties, recycled use must undergo a special recrystallization process. So, how do you determine the optimal temperature and time for a PET crystallization dryer?
🔍 First, the initial moisture content and particle size distribution of the PET raw material are analyzed. In general, the higher the moisture content, the longer the drying time required. For example, if the moisture content of the raw material is 0.5%, it may take 4-6 hours to dry; At 1% moisture, the drying time may need to be extended to 6-8 hours. In addition, the heat and mass transfer properties of PET materials with different particle sizes will also be different, and smaller particles usually dry faster.
🧪 Secondly, a small sample test is carried out. A small amount of PET raw material was taken for drying test with different time and temperature combinations. For example, the temperature of 120°C, 140°C, and 160°C can be set separately, and the drying time at each temperature is 3 hours, 5 hours, and 7 hours, and then the moisture content and product performance after drying can be detected. Evaluate the quality of the dried material, such as crystallinity, color, physical properties, etc., to determine the best drying parameters.
🛠️ Furthermore, consider the subsequent processing process requirements. If the subsequent processing has strict requirements for the moisture content and properties of the PET material, then the corresponding drying time and temperature need to be adjusted. For example, for a high-precision injection molding process, a moisture content of less than 0.02% may be required, which requires higher temperatures and longer drying times.
📚 Finally, refer to the equipment manual and manufacturer recommendations. Crystallizer manufacturers typically provide recommended drying times and temperature ranges based on equipment performance and common applications. For example, some models of crystallizers are recommended to dry at 150 - 180 °C and the drying time is 5 - 7 hours.
📌 To sum up, the temperature of PET crystallization dryer is generally between 150-180°C, and the drying time is about 5-7 hours. By taking into account the characteristics of the raw material, the sample test, the subsequent processing process requirements and the recommendations of the equipment manual, the optimal drying temperature and time parameters can be determined.