Closed plastic mixers are called internal mixers. In order to adapt to the application of mixed waste plastics, a waste plastic internal mixer has been developed. The internal mixer is a machine equipped with a pair of rotors with a specific shape and rotates relative to each other, and intermittently chews and kneads polymer materials in a closed state with adjustable temperature and pressure, rotor sealing device, feeding and compacting device , unloading device, transmission device and frame and other parts.