Procédé de rinçage de surface métalliques enduitess

• Main Authors: L. STEINBRECHER, W.S. HALL
• Format: Patent
• Language: French
• Published: 02.10.1972
• Subjects: ADHESIVES; APPLYING LIQUIDS OR OTHER FLUENT MATERIALS TO SURFACES, IN GENERAL; CHEMICAL PAINT OR INK REMOVERS; CHEMICAL SURFACE TREATMENT; CHEMISTRY; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING COMPOSITIONS, e.g. PAINTS, VARNISHES ORLACQUERS; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; CORRECTING FLUIDS; DIFFUSION TREATMENT OF METALLIC MATERIAL; DYES; FILLING PASTES; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; INKS; METALLURGY; MISCELLANEOUS APPLICATIONS OF MATERIALS; MISCELLANEOUS COMPOSITIONS; NATURAL RESINS; PAINTS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; PERFORMING OPERATIONS; POLISHES; PROCESSES FOR APPLYING LIQUIDS OR OTHER FLUENT MATERIALS TOSURFACES, IN GENERAL; SPRAYING OR ATOMISING IN GENERAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; TRANSPORTING; USE OF MATERIALS THEREFOR; WOODSTAINS

1349826 Coating metal AMCHEM PRODUCTS Inc 12 June 1972 [14 June 1971] 27318/72 Heading B2E A film-forming material is supplied to the surface of a metal susceptible to acid-etching by contacting the metal surface with a coating- forming composition comprising a film-forming material in an aqueous phase containing a metal-etching acid and an oxidising agent, thereafter rinsing the deposited coating with a solution containing hexavalent chromium. Preferably the rinse solution is one in which the hexavalent chromium has been partially reduced with formaldehyde. The rinse solution may contain phosphoric acid to prevent gelling, water-soluble or water-dispersable polyacrylic acid. Preferably the pH of the rinse solution is less than 3.3. The rinse solution may be applied by spraying or by immersing the coated surface in the rinse solution. The film-forming material may be a fatty acid, e.g. stearic acid or preferably a synthetic resin, e.g. polyethylene, polyacrylic resin, styrene-butadiene copolymer. The preferred acid is hydrofluoric acid. Preferably the pH of the coating composition is 1.6-3.8. Examples of oxidizing agents are perborate, bromate, permanganate, nitrite, nitrate and chlorate, preferably added as an alkali metal or ammonium salt. The preferred oxidising agents are hydrogen peroxide and dichromate, preferably added as an aqueous solution of chromic acid and calcium carbonate or an aqueous solution of potassium dichromate and calcium acetate. A preferred coating composition comprises (a) 5-550 g/l of solid resin dispersed in the composition, (b) 0.4-5 g/l of fluoride ion, (c) hydrogen peroxide or dichromate present in amount of 0.01-0.2 g/m equivalent per litre of composition, and (d) hydrogen ion in amount sufficient to impart a pH of 1.6-3.8 to the composition. Further optional ingredients include coalescing agent, preferably ethylene glycol mono-butyl ether, a wetting agent preferably a non-ionic or anionic wetting agent, water-dispersable pigment, a chelating agent. The metal surface may be ferrous metal, zinc or a zinc-coated ferrous metal surface, optionally having a previous non-siccative coating applied on it, e.g. a phosphate, chromate, oxalate, oxide (anodized or chemically-converted) coating. The synthetic resin may be fused after the rinse. The rinse solution may contain sufficient chromium to reduce the gloss of the coating.