METHOD AND APPARATUS FOR PULVERIZING, MIXING AND GRANULATING BY USING TWIN SCREW EXTRUDER

摘要

PROBLEM TO BE SOLVED: To stably and inexpensively granulate a plastic raw material comprising two or more components having different thermal deformation temperatures.SOLUTION: There is disclosed a method of pulverizing, mixing and granulating the plastic raw material 7 comprising two or more components having different thermal deformation temperatures using a twin screw extruder 1 having a pair of screws 3 which rotate in the same direction with respect to each other in a heating/cooling cylinder 4. The axial length (L) of an opening 5 for the raw material supply of the cylinder 4 is made to be ≥1.7D and ≤5D (D is an inner diameter of the cylinder). A cross-sectional profile perpendicular to an axis in each screw 3 below the opening 5 is made to be an angular or half-angle flight screw. Water is supplied into the cylinder in an amount of ≥0.6 to <4% based on the plastic raw material 7. A gas component is removed from a vent 21 before discharging from the cylinder, the plastic raw material volume-reduced, pulverized, melted and mixed, and the melted plastic raw material is granulated in a pellet form by a die 22 and a granulating device 23 provided at the end 4a of the cylinder.