Multi-layer ptfe coatings on heat resistant materials

摘要

Heat-resistant materials are coated with an aqueous dispersion of p.t.f.e. in the presence of a surfactant, the layer is dried and sintered and prior to or during the deposition of the second and subsequent layers, the surface of the coated material is rubbed to give an electronegative charge on the p.t.f.e. surface(s). Preferably, the surface is rubbed by drawing the materials over two rollers covered with cloth or felt, the aq. p.t.f.e. polymer dispersion contains 4-12% surfactant, based on the wt. of polymer and the heat-resistant material is glass cloth, wire gauze or metal foil. A glass cloth contng. 75-95% p.t.f.e. is used as a dielectric material for slot insulation in electric motors, turn-to-turn and interlayer insulation in transformers and for multi-layer plates in radio engineering, as printed circuits.