Abstract: The stability of a flash fibrillation process for converting thermoplastics materials into fibrils by flash extruding a hot pressurized dispersion of thermoplastics material in liquid through an orifice is improved by inserting a pressure-responsive valve in the orifice which ensures the dispersion is at a specified minimum pressure before it is extruded through the orifice. The minimum pressure should be sufficient to ensure the liquid does not volatilize prior to its extrusion through the outlet.

Abstract: this process applies to printed circuits obtained by the imagewise deposition of nickel using a procedure such as that described in U.S. Pat. No. 3,853,589 followed by electroless copper plating onto the nickel pattern. We have found that by depositing the nickel before the copper, as compared with direct deposition of the copper, gives less deposition on the areas between the conductive paths and hence better insulation between them.The process can be performed in five stages including (a) coating a substrate, for instance by a gravure technique, with an active agent including a water-soluble quaternized bipyridilium compound, e.g. N,N'-dimethyl-4,4'-bipyridilium dimethosulphate or N,N'-bis(4-cyanophenyl)4,4"-bipyridilium dichloride and a suitable binder therefore such as polyvinyl alcohol, (b) imagewise exposing the coating where the conductive paths are to be deposited to sensitizing radiation, (c) contacting the surface with a solution of palladium chloride in hydrochloric acid, preferably containing 0.