THERMAL DECOMPOSITION METHOD FOR ACRYLIC RESIN

PROBLEM TO BE SOLVED: To provide a thermal decomposition method capable of continuously, stably and easily performing thermal decomposition of an acrylic resin for a long period of time under an inert gas atmosphere by a fluidized bed.SOLUTION: In the thermal decomposition method for the acrylic resin, a step (a) of fluidizing a fluidization medium by continuously feeding a fluidized gas containing an inert gas from a lower part of a decomposition tank to the decomposition tank filled with the fluidization medium and forming the fluidized bed, a step (b) of continuously feeding an acrylic resin to the fluidized bed to perform thermal decomposition, cooling the generated gaseous decomposition product and recovering it as a liquid, and a step (c) of continuously discharging the fluidization medium in the decomposition tank from a position at a lower side than the height of a feeding position of the acrylic resin and heating it and thereafter continuously feeding it to the decomposition tank are performed in parallel. At this time, a feeding speed of the fluidized gas fed to the decomposition tank, a feeding speed of the acrylic resin, a feeding speed of the fluidization medium and the temperature thereof are made constant, and a height of the fluidized bed at the thermal decomposition is controlled to a constant height by only control of a discharge speed of the fluidization medium discharged from the decomposition tank in the step (c).