Impermeable layer on inside wall of vessel especially plastic fuel tank

摘要

A layer which is impermeable to liquids and/or gases is produced on the inner surface of a hollow body, esp. a plastic fuel tank, by means of plasma polymerisation. A reactive monomer gas at low temperature (20 - 100 deg C) is introduced into the hollow body while there is a pressure difference between the inside and outside wall surfaces. Energy is supplied to induce polymerisation so that a polymer layer is produced on the inner surface. The layer is built up in steps by controlling the feed of monomer gas so that the consumption of monomer gas during plasma polymerisation exceeds the supply of fresh gas. The plasma is extinguished but the energy supply is maintained and further cross-linking and/or healing of the deposited layer takes place. When the concentration of monomer gas again reaches the required value the cycle is repeated till the desired layer thickness has been reached.