METHOD FOR PRODUCING MULTI-LAYER EXTRUDED MOLDING, DIRECT BLOW MOLDING METHOD, AND MULTI-LAYER EXTRUSION MOLDING APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide a multi-layer extrusion molding method which can reduce the number of extruders, curtails the scale of an apparatus, reduces costs, and is applicable to single-layer extrusion molding. SOLUTION: An apparatus has an extruder 5 for melt-kneading at least two thermoplastic resins different in viscosity and a die 4 fitted to the tip part of the extruder 5, the die 4 has an outer mold 7 having a cylindrical inside surface, an inner mold 8 which has a cylindrical outside surface and is arranged on the same axis in the outer mold 7, and a motor 10 for rotating the outer mold 7 and the inner mold 8 relatively around the axis, by an extrusion molding apparatus 2 in which a ring-shaped channel is formed in the cross section between the inner mold 8 and the outer mold 7, the layer of the higher viscosity rein is formed in the middle in the thickness direction of the ring-shaped channel of small shear stress by the relative rotation of the outer mold 7 and the inner mold 8 by the motor 10, and the layers of the lower viscosity resin are formed inside and outside the higher viscosity resin layer.