Aqueous phosphating composition and process for metal surfaces
AssigneeHenkel Corporation
InventorsMasahiko Kawakami, Naoyuki Kobayashi, Kazuyuki Oyama
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Abstract
An aqueous zinc phosphate conversion coating that contains 5 to 50 g/L of phosphate ions, 0.2 to 10 g/L of zinc ions, and 0.5 to 4.0 g/L as hydroxylamine of a hydroxylamine source, and also: (1) contains 0.01 to 5.0 g/L polycarboxylic acid or salt thereof and/or starch phosphate; or (2) has a zinc ions/phosphate ions weight ratio below 0.27 and a zinc ions concentration of at least 2.0 g/L forms high quality zinc phosphating coatings on metal surfaces even if the surfaces have not been previously conditioned by contact with a dispersion of colloidal titanium.
Claims22
A liquid composition suitable for forming a zinc phosphate conversion coating on a metal surface by contact and reaction therewith, said liquid composition comprising water and the following dissolved components:
- (A) a concentration of 5 to 50 g/L of phosphate ions;
- (B) a concentration of 0.2 to 10 g/L of zinc ions;
- (C) a hydroxylamine source in a quantity that provides a concentration of 0.5 to 4.0 g/L stoichiometric equivalent as hydroxylamine;
- and
- (D) at least one of components (D.1) and (D.2) as follows:
- (D.1) a concentration of 0.01 to 5.0 g/L in total of at least one substance selected from the group consisting of polycarboxylic acids, salts thereof, and starch phosphate;
- (D.2) a concentration of zinc ions that is at least 2.0 g/L and has a ratio to the concentration of phosphate ions in the same liquid composition that is not greater than 0.27:1.0.
Dependencies are inferred from the claim text.