| 摘要 |
<p>PURPOSE:To obtain the tubular foam of a high foaming ratio without uneven wall thickness and deformation, by providing a specified film layer on a core and foam-molding a chemical agent containing polyolefine, maintaining the surface temperature of the core right before the crosshead inlet of an extruder below a specified degree. CONSTITUTION:When a chemical foaming agent (e.g. an azodicarbonamide etc.) is added to a polyolefine (e.g. a polyethylene etc.) and a polyolefine tubular foam of more than three times foaming ratio is extrusion-molded, a film layer composed of the same kind as the polyolefine for foaming or a polymer having a lower melting point is provided on a core 1 and an aimed tubular foam is obtained by passing the core 1 through the crosshead of an extruder maintaining the surface temperature of the core 1 right before the crosshead inlet of an extruder below 50 deg.C and forming a foam layer 2 on the outside of the core 1.</p> |
