Method for the surface treatment of thermoplastic materials

In a process for the corona discharge surface treatment of thermoplastic material, wherein a continuum of said material is passed through an air gap between stationary bar type and relatively large roller type electrodes across which high voltage is impressed, the improvement which comprises employing, as said stationary bar type electrode, a metallic substrate of high electrical conductivity having a continuous coating layer of porcelain enamel dielectric material;

• and an outer continuous shielding layer of material thereover consisting essentially of at least one member selected from the group consisting of refractory metal oxides, nitrides, carbides and borides having properties of high mechanical strength, chemical stability at elevated temperatures and high thermal conductivity.