To provide a pretreatment method for classifying material quality with sufficient purity in classifying the material quality of a crushed piece raw material of crushed waste plastic.
A method for classifying the quality of the waste plastic crushed piece raw material obtained when disassembling and crushing waste plastic products or the like and classifying them every valuable to recycle them comprises a heat pretreatment process (a heating process) for heating the waste plastic crushed pieces at a predetermined temperature at which the waste plastic crushed pieces are thermally deformed in a pre-process of material quality classification (a plastic sorting process) at least. The waste plastic crushed pieces supplied for the material quality classification (the plastic sorting process) are respectively separated without being in the mutually connected state under drawing action (restoring action) due to thermal deformation by heating, and furthermore, shape is made simple. The waste plastic crushed pieces can thereby be classified one by one in material quality classification, and in consequence, the raw material waste plastic crushed pieces can be classified with sufficient purity.
HOSOFUJI SHINJI
KISHIMOTO KOHEI
