| 摘要 |
A layer of noble metal (i.e. metal more noble than copper) is formed on a non-metallic hydrophilic surface by first activating the surface with mercury by reacting a mercurous compound in the presence of water with an agent which reduces or disproportionates the compound and then depositing noble metal by reduction of a compound thereof in solution. Suitable surfaces are polystyrene, polyacrylate and phenol-formaldehyde when treated with chlorosulphonic acid; saponified cellulose acetate, polyvinyl acetate and polyvinyl chloride; glass coated with silica gel; and gelatin, regenerated cellulose, paper, wood and polyvinyl alcohol. The surface may be treated with the mercurous compound and the agent successively; suitable solutions contain respectively mercurous nitrate optionally together with a hydroxy acid such as citric, tartaric, glycollic, glyceric or malic acid, and thiosulphate, carbonate, sulphite, thiocyanate, thiourea, nitrite, sulphide, cyanide or borofluoride. The noble metal may be deposited from a solution containing silver nitrate and a reducing agent such as hydroquinone, p-phenylene-diamine, pyrogallol or hydrazine. The layer may be coloured, electroplated, coated electrophoretically or lacquered. Its resistance may be reduced by heating, rubbing or treatment with a solution containing a potential determining anion with respect to the noble metal. It may be a continuous coating or may be a pattern, e.g. for a screening grid, circuit pattern or radio stationname dial. Specification 953,431 is referred to. |
