MANUFACTURE OF FINE FOAMABLE MATERIAL AND EXTRUSION MOLDING MACHINE FOR MANUFACTURING THE SAME

PROBLEM TO BE SOLVED: To stably and continuously obtain a fine foamable material wherein fine air bubbles are uniformly dispersed by setting the pressure for introducing a foaming agent into a resin to a specific value, and setting the pressure of the kneaded resin at the outlet part of an extruder to a specific value with respect to the pressure in a foaming agent introducing part. SOLUTION: The pressure for introducing a foaming agent into a resin is set to 100 kgf/cm2 or less and the pressure of the kneaded resin at the outlet part of an extruder is made 1.3 times or more the pressure in a foaming agent introducing part. That is, the cylinder 8 storing the foaming agent in a foaming agent supply device 2 is connected to the downstream part of the hopper 4 of a screw extruder 1 through a pressure adjusting valve 9, a pump 10 and a temp. regulating heater 11. At first, a resin material is supplied to a cylinder 3 from the hopper 4 and, subsequently, the foaming agent supplied from the foaming agent supply device 24 is introduced into the resin material, and the kneaded fine foamable resin material is discharged from the die 7 being the outlet part of the extruder.