| 摘要 |
<p>Multilayer covers for protecting agricultural or other external areas includes >=1 layer of coloured polyvinylfluoride (PVF) film and >=1 layers of an organic foam, metallised polyester film, Al foil or PVC film, esp. as covers on a sandwich structure. For covers required to exclude direct sunlight and infra red radiation and to trap absorbed heat overnight, to protect e.g. plants, yound animals, sports grounds, swimming pools, etc. The covers may be used flat or supported on hoop frameworks. Covers which include a layer of flexible foam made of polyester, polyurethane and PVC resin, or a layer of rigid phenolic foam are also claimed. Various examples, are described with between three and six layers in each cover, adhesive-bonded together. One form included a honeycomb structure sheet enclosed on each face with layers of metallised polyester or polyamide an dof coloured polyvinyl fluoride film.</p> |
