| 摘要 |
1,116,349. Laminates. IMPERIAL CHEMICAL INDUSTRIES Ltd. 6 Aug., 1965 [24 Aug., 1964], No. 34511/64. Heading B5N. A process for the continuous manufacture of laminated articles consisting of a polyurethane foam core sandwiched between and bonded to two sheets of facing material comprises imparting motion to the lower of the said sheets of material, applying a layer of a liquid mixture of polyurethane foam-forming ingredients to a surface of the said sheet while it is in motion, heating, at least in part by radio frequency heating to bring about foam formation in the said layer and imparting motion to the other of the said sheets of materials so as continuously to bring it into contact with the free surface of the foam before setting thereof is complete. Radio frequency heating means heating under the influence of an electric field having a frequency above 50 megacycles per second, such as 80, 892 and 2,450 megacycles. Suitable sheets of material includes sheets or boards composed of paper, wood, paperboard, plaster board or asbestos and certain plastics and rubbers. Other methods of heating may be used if desired to supplement the radio frequency heating, for example the sheet or sheets of material may be preheated by exposure to a source of radiant heat such as an infra-red heater or by passage through heated ovens or tunnels. It is convenient to use two conveying surfaces one for each sheet, which are parallel to each other and move in co-operation with each other. The conveying surfaces may be in the form of an endless belt of, for example, woven fabric or wire mesh, which may be covered with rubber or with a plastics material. The foamforming ingredients may be applied by means of compressed air. The mixture may be applied to the sheet before it contacts a conveying surface. Heating of the foam-forming ingredients may occur either before or after or before and after the second sheet of facing material has been introduced on to the layer. |
