| 摘要 |
An extruded, foamed aliphatic thermoplastic resin comprises a mass of substantially parallel elongated cells enclosed by a surface skin, the cells being orientated substantially at right-angles to the surface skin. The blowing agent is preferably a normally gaseous substance, e.g. a butane. The foamable composition preferably contains a nucleating agent, e.g. finely-divided silica. The product may be produced by extruding the foamable resin composition through a die orifice into a zone of lower pressure defined by stationary surfaces that are cooled so as to solidify the resin in contact with them and are spaced progressively further apart from each other along the direction of extrusion such that foaming of the resin occurs as it moves through the zone. Preferably there is a "step" between the die orifice and the apex of the stationary surfaces. |
