| 摘要 |
1,170,261. Foamed coating. R. I. KLIENE. 10 April, 1967 [23 March, 1966], No. 12911/66. Heading B2E. [Also in Divisions B5 and El] A composite plastics material is produced by heating one side of a layer of powdered theromplastics material such that the side of the produced sheet corresponding to said one side of the layer has a smooth surface and the side of the produced sheet corresponding to the other side of the layer has a rough porous surface, and forming a foam plastics material on the rough porous side of the sheet produced corresponding to the other side of the layer whereby the foamed material penetrates the porous side to form an inseparable physical bond therebetween. The thermoplastics material may be polyethylene, polypropylene, cellulose acetate butyrate, polyvinyl chloride, acrylics. The foam layer may comprise polyurethane. The polyethylene layer may be formed by spreading the powder onto the walls of a closed mould by rotation, the mould being heated from the outside; alternatively the powder may be sintered in a stationary mould, preferably such that one side was impermeable. In both cases a more and more granular structure is produced as the layer increases in thickness. A mixture of powders in which one constituent has a lower softening temperature than the other may be used, the component of lower softening temperature then forming the outer non-porous layer of the sheet and the component of higher softening temperature the inner porous part. The porosity may be accentuated by blending a powdered chemical blowing agent with the powdered polyethylene. In an embodiment of the invention a water tank is made in two parts, the lid and the body of the tank, each being made in hollow form in rotational moulds and then filled with polyurethane foam. The bond between the polyethylene and the polyurethane allows holes to be drilled in the tanks during installation without damage to the inner skin of the tank. |
