| 摘要 |
A roofing sheet comprises an upper and a lower reinforcing layer of inorganic fibrous material, a layer of bituminous composition between the two reinforcing layers, and a coating of bituminous material over each of the two reinforcing layers, the flexibility of the upper reinforcing layer being at least 50% greater than that of the lower reinforcing layer. The reinforcing layers may consist of glass fibre mats and/or woven or weave like structures of glass fibres, or asbestos felt mats. A roofing sheet comprises bitumen and upper and lower reinforcing layers embedded in it, as claimed in Specification No. 1,008,315 in which the surface of the sheet disposed adjacent to the upper reinforcing layer bears a protective facing of finely divided mineral material e.g. broken slate, gravel, granite chips, sand or ceramic material, and the upper reinforcing layer consists of a glass fibre mat having at least 50% greater flexibility than the lower reinforcing layer. The upper reinforcing layer may be thinner than the lower or the upper reinforcing layer may weigh less per unit area than the lower. The upper reinforcing layer may comprise a binding medium. The flexibility of the upper reinforcing layer being increased by the nature of the binding medium and/or by controlling the quantity of binding medium used. Indentations may be present in the upper reinforcing layer. The indentations may be made by means of a ball stamping mill or by a stamping process. ber 37, Fig. 2, having two nearly tangetical axially elongated inlets 69, Fig. 3, registering with supply passages 45, 47, the mixture being ejected as a whirling continuous stream or coarse spray from the outlet 39 which is the same diameter as the mixing chamber. A plunger 15 can be moved to the broken line position in which it protrudes from the outlet opening, occluding the fluid inlets and scraping the mixing chamber clean of mixture. As described the members 49 are of polytetrafluoroethylene or other organic elastomer and are under compression so that the diameter of the bore 37 is slightly less than that of the plunger; the inlets 69 are formed by recesses in the mating surfaces of two identical halves of a valve body 53 (see also Fig. 4, not shown). The plunger 15 is actuated pneumatically and the invention may be embodied as a gun (Fig. 1, not shown) for polyurethane foam for coating solid substrates, caulking, or filling moulds or insulation cavities. Low pressure air, principally for cleaning purposes, is discharged concentrically with the liquid mixture. |
