| 摘要 |
PURPOSE:To reduce the generation of corrugation by dividing an annular cooling device into at least two sections and raising the internal pressure of a cylindrical foamed body between a die and the annular cooling device as well as between two annular cooling devices to impart a tension state to the inner surface of the foamed body. CONSTITUTION:When the foamable polyolefin resin composition in an extruder 1 is extruded from the annular die formed to the leading end of the extruder 1, the resin composition becomes a cylindrical foamed body 4 which is, in turn, successively cooled by annular cooling devices 3a, 3b but the pressure in the cylindrical foamed body 4 is raised by the air supplied from the air supply port 5 provided between the annular die 2 and the first annular cooling body 3a. An air supply port 6 is also provided between the first annular cooling device 3a and the second annular cooling device 3b and the internal pressure of the cylindrical foamed body 4 is also raised between the first and second annular cooling devices 3a, 3b by the air supplied from the air supply port 6. By this method, a foamed polyolefinic resin sheet reduced in corrugation can be obtained. |
