| 摘要 |
Expanded thermoplastic resin sheet is produced by extruding an expansible synthetic thermoplastic resin through a die slot into an expansion zone defined by two opposed curved surfaces held at a temp below the extrusion temp. one of the surfaces being a concave surface displacing in the extrusion direction, and the other surface being concave, so that expansion of the resin occurs as it passes through the expansion zone, and the curvature and relative spacing of the surfaces being such that they contact the expanding resin. Smooth finish is produced on the upper and lower faces and tearing of the sheet is avoided. Sheets of different thicknesses, densities and types can be produced. |
