| 摘要 |
<p>An industrial swinging door, of the type used in warehouses, supermarkets etc. to be opened by a trolley pushing through it, has an upper transparent panel of polycarbonate, a lower panel of plasticised PVC to accept the knocks from trolleys, and a fabric facing bonded to both sides of this lower panel and extending sufficiently far onto the polycarbonate panel to form the connection between them. With this arrangement, the useful transparent and easily cleaned properties of the polycarbonate are utilised for the top part of the door, while its low impact resistance does not occur in the lower part, for which purpose plasticised PVC is used. In a variant, the two panels are joined together by lapping strips of elastic plastics material. The common edge may be serrated.</p> |
