Corrosion protection coatings for metal surfaces - with primer layer, adhesion layer and thermoplastic covering layer applied as preheated powder coating to limit heat energy for sintering

摘要

Protective coverings to protect metal surfaces against corrosion, consist of a relatively thick thermoplastic layer, a thin adhesion promoting layer on the metal surface and a thin layer of adhesive between the two, at least the surface layer being applied by sintering, characterised in that in order to control the sintering energy, at least the powder for the surface layer is preheated. ADVANTAGE - Multilayer sintered thermoplastic corrosion protective layers can be applied by successive application of the layers as powder coatings to the heated substrate. It offers greater flexibility of operation than extrusion application processes together with improved adhesion of the coating which gives better corrosion resistance. Preheating of the coating powder allows the applied layer to be fully sintered without the necessity of heating the substrate to such high temps. that degradation of the coating compsn. would result or that the danger of self-ignition of the coating or of dust explosions would arise.