| 摘要 |
<p>1410910 Coated woodwool slabs B P B INDUSTRIES LTD 25 Sept 1972 [30 Sept 1971] 45542/71 Heading B2E A woodwool slab, or other building slab or board of the same texture and porosity, is rendered showerproof by applying thereto in a form other than a pre-formed layer a waterresistant thermoplastic material optionally containing a filler. The thermoplastic material may comprise bitumen, coal tar or other pitch, particularly a hard bitumen of softening point 70-160‹C and penetration 5-50. Many fillers are specified, especially waste or reclaimed materials, including (in the examples) sand, limestone powder, pulverised fuel ash, fine slate flour, comminuted waste bitumen felt and finely ground woodwool slab. The thermoplastic material is usually spread as a layer not more than 3 mm thick by means of a trowel, doctor blade, hot roller, extrusion or curtain coating and may be subsequently rolled by means of a roller wetted with soap as an antibonding agent.</p> |
