Decomposition method and decomposition apparatus for resin

A decomposition apparatus for resin, comprising:

• a cylinder;
• a resin supplier supplying a thermoplastic resin to be decomposed, to the cylinder;
• a screw transporting the supplied thermoplastic resin and the melt-plasticized thermoplastic resin in the cylinder;
• a fluid supplier supplying a heated and pressurized fluid into the cylinder in order to decompose the melt-plasticized thermoplastic resin in a subcritical state or a supercritical state;
• an extruder provided at a tip of the cylinder and extruding a decomposed product of the thermoplastic resin to outside of the cylinder;
• and
• a backflow suppression mechanism including, in the cylinder provided between the resin supplier and the fluid supplier, at least one selected from a resin thermometer for measuring a temperature of the thermoplastic resin, a resin pressure gauge for measuring a pressure of the thermoplastic resin, a cylinder thermometer for measuring a temperature of the cylinder, and a screw measuring meter for measuring an energy consumption or a drive torque of a rotary drive mechanism driving the screw, the backflow suppression mechanism capable of suppressing the backflow of the melt-plasticized thermoplastic resin in accordance with at least one of the measured values of the resin thermometer, the resin pressure gauge, the cylinder thermometer, and the screw measuring meter.