Patent GB-1171932-A (GB)
Title: Coated Articles.
IPC: B32B5/24
Filed: 1966-10-28
Abstract: 1,171,932. Foam-coated fibrous sheet. CARL FREUDENBERG. 28 Oct., 1966 [1 Nov., 1965], No. 48518/66. Heading B2E. [Also in Division B5] An air-permeable article e.g. a sheet of leather substitute, comprises a fibrous sheet coated on one or both sides with a coating that is securely bonded to the fibrous sheet by being impregnated into the sheet only partially through the thickness of the sheet and that is of open-cell polyurethane foam and has a microporous outer skin. The outer skin of the or each coating may be of polyurethane and is integral with the coating with which it is associated. The or each coating of polyurethane foam may extend about one third through the thickness of the sheet. The article may be made (a) by laying a preformed microporous skin over a mould surface and applying over the skin a polyurethane foam-forming paste, initiating polymerisation and foaming of the paste under conditions such that an open-cell polyurethane foam is formed and then pressing a fibrous sheet material onto the foaming paste under conditions that result in impregnation only partially through the thickness of the sheet and, after foaming and polymerisation is completed, stripping the article off the mould surface; (b) by applying over a mould surface a polyurethane foam-forming paste, initiating polymerisation and foaming of the paste under conditions such that an open cell polyurethane foam is formed and then pressing a fibrous sheet material onto the foaming paste under conditions that result in impregnation only partially through the thickness of the sheet and, after foaming and polymerisation is completed, stripping the article off the mould surface, a microporous outer skin being formed integral with the coating; or (c) by applying a polyurethane open cell foam-forming paste onto a mould surface having available on it a polymerisation catalyst for the polyurethane, initiating polymerisation and foaming, to yield an open cell foam, and then pressing a needled fleece onto the foaming paste at a time and with a pressure such that the sheet collapses by between 10 and 20% in thickness and is penetrated by the foam to about one third of its resultant thickness, and after foaming and polymerisation is completed stripping the article off the mould surface. The paste may be applied to a continuously moving mould surface, the sheet material continuously pressed onto the foaming paste and the article produced continuously stripped off the mould surface. In method (b), the duration of the polymerisation and foaming before the sheet material is pressed onto the foaming paste and the pressure of application of the sheet material are both such that the polyurethane extends about one third through the thickness of the sheet material. The sheet material may be a fleece and the duration and the pressure are such that the fleece collapses by between 10 and 20% in thickness on impregnation with the foam. The mould surface may have available on it a polymerisation catalyst for the polyurethane. The mould surface may be of cold cured silicone rubber. An organo-tin compound may be applied previously, as the polymerisation catalyst, to the mould surface.