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1. EP0048718 - COMPOSITION FOR INHIBITING CORROSION OF METAL SURFACES

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

Claims

1. A process for treating ferrous or non-ferrous metal surfaced articles to improve corrosion resistance and receptivity to synthetic resin coatings which comprises bringing said surface into contact with a chromate depositing solution composed of water, and ingredients consisting essentially of the following:

the ratio of said additive to the total acids being such as to give a pH within the range of 1.5 to 3.6 at 22°C and a chromate concentration of 0.05 to 10.0 grams per liter, as Cr, the metal surfaced article being dried without rinsing and a coating composition which dries to a water resistant film being applied thereto.
  2. A process for treating ferrous or non-ferrous metal surfaced articles as claimed in claim 1 in which the additive is zinc oxide.
  3. A process for treating ferrous or non-ferrous metal surfaced articles as claimed in claim 1 in which the additive is magnesium oxide.
  4. A process for treating ferrous or non-ferrous metal surfaced articles as claimed in claim 1 in which the additive is magnesium hydroxide.
  5. A process for treating ferrous or non-ferrous metal surfaced articles as claimed in claim 1 in which the additive is aluminum sulfate.
  6. A process as claimed in claim 1 in which the coating composition is an arylic resin coating composition.
  7. A process as claimed in claim 1 in which said ferrous and non-ferrous metals are from the group consisting of cold rolled steel, aluminized and galvanized iron and steel, aluminum, aluminum-zinc alloys, magnesium and magnesium-aluminum alloys.
  8. A process as claimed in claim 1 in which said metal surfaced articles are in the form of sheets, coils, wires, tubes or rods which are brought into contact with said chromate depositing solution at a linear speed of at least 50 feet (15.2 m) per minute, the said solution being effective to deposit at least 0.2 mg/square foot (2.15 mg/m 2) of chromate, as Cr.
  9. A process as claimed in claim 1 in which the additive is zinc oxide and the weight ratio of chromic acid to zinc oxide is approximately 2.1.
  10. A process as claimed in claim 1 in which the metal is aluminum and the ratio of the additive to the total acids is such as to give a pH within the range of 1.8 to 3.5 at 22°C.
  11. A process as claimed in claim 1 in which the metal is galvanized iron or steel and the ratio of the additive to the total acids is such to give a pH within the range of 1.8 to 3.5 at 22°C.
  12. A process as claimed in claim 1 in which the metal is cold rolled steel and the ratio of the additive to the total acids is such as to give a pH within the range of 1.8 to 3.5 at 22°C and the composition contains hydrofluosilicic acid.
  13. A process as claimed in claim 1 or claim 2 in which the additive is zinc oxide and the amount thereof corresponds to 1 to 6 grams per litre.
  14. A process as claimed in claim 1 wherein the chromate depositing solution has a solids content within the range of from 0.2 to 75.0 grams per litre.