Drying process of transparent plastics: material process drying temperature (℃) drying time (H) material layer thickness (mm) remarks pmma70 ~ 802 ~ 430 ~ 40pc120 ~ 130 > 6 < 30 hot air circulation drying pet140 ~ 1803 ~ 4 continuous drying feeding device is preferred.
Cleaning of barrel, screw and its accessories in order to prevent raw material pollution and the existence of old materials or impurities in the depression of screw and accessories, especially the existence of resin with poor thermal stability, screw cleaning agent shall be used to clean all parts before use and after shutdown, so that there shall be no impurities. When there is no screw cleaning agent, PE, PS and other resins can be used to clean the screw.
In case of temporary shutdown, in order to prevent the degradation of raw materials due to long residence time at high temperature, the temperature of dryer and barrel should be reduced, such as PC, PMMA and other barrel temperatures should be reduced below 160 ℃. (the hopper temperature shall be reduced below 100 ℃ for PC).
Due to the high transmittance of transparent plastics, the surface quality of plastic products must be strict, and there shall be no spots, pores and whitening. Fog halo, black spots, discoloration, poor gloss and other defects, so the raw materials and equipment are damaged in the whole injection molding process in Dalian. Mold and even product design should pay great attention to and put forward strict or even special requirements.
Secondly, because most transparent plastics have high melting point and poor fluidity, in order to ensure the surface quality of products, it is often necessary to make subtle adjustments to the process parameters such as high temperature, injection pressure and injection speed, so that the mold can be filled during injection without internal stress causing product deformation and cracking. Therefore, strict operation should be carried out in terms of raw material preparation, equipment and mold requirements, injection molding process and raw material treatment of products.
