METHOD FOR OPERATING UNDERWATER CUTTING AND GRANULATING APPARATUS

摘要

PROBLEM TO BE SOLVED: To prevent cooling water from penetrating inside from nozzle holes of a die and to facilitate restarting by a method wherein when a kneading extruder is stopped, heating retention temperature of the a die holder is immediately lowered around m.p. of a resin and viscosity of the resin is prevented from being lowered. SOLUTION: A thermoplastic resin fed to a kneading part 1 of a kneading extruder 5 through a hopper 6 is kneaded by a rotating screw 4. Impurities and foreign matters in the resin are removed in a die holder part 7 and the resin is extruded into a strand- like shape in an underwater cutting apparatus 9 and the strands are cut into a pellet- like shape by means of an underwater cutting knife 9b and cooling water and pellets are separated by a cooling water dehydrating device 14 and adhered water is removed by a drying device 15 to send them to a silo 17. When operation of the underwater cutting and granulating apparatus is stopped, rotation of the kneading extruder 5 and the underwater cutting knife 9b is stopped but circulation of the cooling water is continued and immediate after that, temp. of the kneading part 1 and the die 8 is lowered and as the result, restarting can be extremely smoothly performed without penetration of the cooling water and deterioration of quality of the resin.