Manufacturing method of different color pellets and manufacturing apparatus therefor

A method for manufacturing different color pellets by using an apparatus in which two granulating units are provided with a screw kneading extruder for molding pellets out of molten resin discharged from a discharge port of said screw kneading extruder, comprising the steps of:

• supplying a thermoplastic resin material of one color to said screw kneading extruder in the condition that one of said granulating units communicates with said discharge port;
• blocking the other granulating unit so that pellets of said one color are molded by said one granulating unit;
• stopping the supply of said thermoplastic resin material of said one color to said screw kneading extruder;
• opening said discharge port to the outside of said apparatus while blocking said one granulating unit;
• supplying a thermoplastic resin material of another color to said screw kneading extruder while kneading, melting and releasing said thermoplastic resin of said another color to the outside of said apparatus through said discharge port to thereby sweep thermoplastic resin material of said one color out of said screw kneading extruder;
• communicating said discharge port with said other granulating unit while said one granulating unit remains blocked;
• supplying said thermoplastic resin material of said another color to said screw kneading extruder so that pellets of said another color are molded by said other granulating unit.