Coating of polyurethane foam

931,114. Coated foamed articles. DUNLOP RUBBER CO. Ltd. April 22, 1960 [May 22, 1959], No. 17422/59. Class 140. Polyurethane foam articles, e.g. sheets, are coated by moistening the foam with water in the liquid or gaseous phase, spreading on at least one surface thereof a layer of an activated polyurethane prepolymer syrup and curing the layer by heating under pressure to produce an adherent polyurethane coating of greater density than that of the foam. The moistening may either precede or follow the step of spreading the prepolymer syrup. The prepolymercoated foam may be compressed at a compression ratio, defined as being the ratio of the volume of the foam before treatment to the volume after treatment, in excess of 2: 1 at an elevated temperature. The layer of activated prepolymer syrup may be formed from the reaction product of a polyether, polythioether, polyester, polyesteramide or polyamide, examples of which are given, and a molar excess of an organic polyiso- or polyisothio-cyanate, e.g. 2,4- or 2,6-tolylene diisocyanate and 1,4- naphthalene diisocyanate. The layer of syrup may contain a colouring material, e.g. dyes or pigments, of which examples are given, and may be patterned when curing by heating under pressure. Suitable catalysts are N-methylmorpholine and triethylamine. The thickness of the cured layer may be from 0.3 to 1.2 mm. In an alternative method, the prepolymer syrup is spread on dry polyether polyurethane foam and heated in live steam for approximately 30 minutes. Specification 898,271 is referred to.