HATSUHOHORIOREFUINKEIJUSHISHIITONOSEIZOHOHOOYOBISEIZOSOCHI

摘要

A foamed polyolefin sheet is formed by extruding a molten polyolefin resin, which contains a blowing agent, into a low-pressure zone through an annular die provided at an end of an extruder to form a foamed tubular body, bringing the foamed tubular body into contact with a peripheral surface of a cylindrical cooling device to cool the foamed tubular body and then slitting the thus-cooled foamed tubular body in the direction of extrusion to open same. The cylindrical cooling device is divided into at least two sections. The internal pressure of the foamed tubular body is increased between the die and the upstream section of the cylindrical cooling device and also between at least two adjacent sections of the cylindrical cooling device to apply tension to the foamed tubular body at the inner wall. An apparatus for the formation of the foamed polyolefin sheet is also disclosed.