| 摘要 |
The invention relates to web-form foam boards made from polyolefins produced from polyolefin moulding compositions containing blowing agents by extrusion, foaming and expansion of these compositions and during whose production halogen-free hydrocarbons and/or CO2 are used as blowing agents. Directly after their production, without additional ageing, the foam boards according to the invention have a blowing agent content which is more than 30% lower than that of products of the same production type known hitherto. The new foam boards according to the invention are characterised in that the board surface has been needle-perforated within a maximum of 3 hours after extrusion. They have very good thermal stability. The production of the foam boards according to the invention is carried out by known processes in known apparatuses, where the product is, according to the invention, additionally needle-perforated immediately after it has achieved its inherent strength after extrusion. |
