| 摘要 |
<p>The sheet consists of rigid foils, with a flexible covering foil on at least one external side, and a solid filling between them. One external foil has inward pointing recesses, the base of which connects it to its neighbouring foil. The other external foil has no recesses, but apertures, and is covered by the covering foil. The rigid foil consists pref. of steel sheeting or aluminium, while each covering foil consists of butyl rubber, while the solid filling consists of polyurethane foam.</p> |
