| 摘要 |
PURPOSE: To manufacture a molded piece of excellent quality with a good yield by a foamed sheet whose dimensional stability at molding with heat is excellent so that the foamed sheet is not torn nor corrugated in manufacturing a molded piece. CONSTITUTION: A foamed sheet is formed by melting and kneading a polycarbonate resin and a foaming agent with an extruder and extruding the kneaded matter from a die at the tip of the extruder to a low pressure area. When an average cell diameter and a cell shape of the foamed sheet satisfy the following conditional expressions 1<X/Z<=3, 1<Y/Z<=5, (X+Y+Z)/3>=0.1mm, wherein X represents an average cell diameter (m) in a direction crossing a sectional thickness direction of a sheet width direction, Y represents an average cell diameter (mm) in a direction crossing a sectional thickness direction of a sheet extruding direction, and Z represents an average cell diameter (mm) in a thickness direction of the sheet cross section, a polycarbonate resin extrusion foamed sheet can be obtained. |
