Abstract: A plastic tube extruded from an extruder is conveyed through a plasma treatment apparatus. The plasma treatment apparatus is equipped with a tubular electrode body having a high-voltage side electrode and a grounded-side electrode disposed on a tubular insulator and a high frequency electric power source connected to the electrodes. When the plastic tube is conveyed through the electrode body with one end of the tube open to the atmosphere, a mixture of a glow discharge-stabilizing gas and a treating gas is fed into the other end of the tube and an alternating-current high-voltage is applied to generate a plasma region at a pressure near to atmospheric pressure in which the tube is treated with a glow discharge plasma. This method allows an interior and/or exterior surface of a plastic tube designed to convey a medical fluid to be continuously treated by a glow discharge plasma at atmospheric pressure to form an anti-thrombotic and blood-compatible film on the surface treated.

Abstract: This invention concerns a SiO.sub.2, SiN.sub.x protection film formed by a CVD or PVD gas phase glowing method capable of preventing melting of the matrix ingredients at the surface of a dielectric material in electric discharge of an ozone generator and it relates to a dielectric material used for an ozone generator capable of overcoming the problems for the abrasion of electrode and dielectric material or melting of ions or molecules of during electric discharge, as well as a method of forming a protection film therefor based on the finding that an SiO.sub.2 film or SiN.sub.x film can be formed easily on a surface of a predetermined electric material or, further, on a surface of electrode by processing a specific reaction gas, for example, comprising a crude gas such as SiH.sub.4, SiCl.sub.4, N.sub.2, NH.sub.