Use of substituted hydroxylamines in metal phosphating processes
AssigneeHenkel Kommanditgesellschaft auf Aktien
InventorRichard Church
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Abstract
Alkyl-substituted hydroxylamines are useful as aids in the phosphating of metal substrates. In particular, the rate of phosphating and the rate at which manganese compounds are dissolved into aqueous phosphoric acid solutions may be accelerated by alkyl-substituted hydroxylamines.
Claims20
A phosphate conversion coating composition which is acidic and which is comprised of:
- a) water;
- b) cations selected from zinc cations, alkali metal cations, ammonium cations or mixtures thereof;
- c) phosphate ions;
- and
- d) a water-soluble substituted hydroxylamine corresponding to general formula
- 2
- wherein R1, R2 and R3 are the same or different and are independently selected from H and C1- C6 alkyl, subject to the proviso that R1, R2 and R3 are not all H, or a salt of said water-soluble substituted hydroxylamine.
A zinc phosphate conversion coating composition which is acidic and which comprises:
- a). water;
- b). zinc cations;
- c). phosphate ions;
- and
- d). a substituted hydroxylamine selected from N-isopropyl hydroxylamine, N,N-diethyl hydroxylamine, salts thereof or mixtures thereof.
A zinc phosphate conversion coating composition having a pH of 1 to 2 and comprising:
- a). water;
- b). 1.8 to 2.2 weight % zinc cations;
- c). 2.7 to 3.3 weight % phosphate ions;
- d). 0.02 to 0.05 weight % N,N-diethyl hydroxylamine or salt thereof;
- e). 50 to 70 ppm Ni:
- f). 3.2-3.8 weight % nitrate;
- and
- g) 0.015 to 0.025 weight % sulfamic acid.
An improved method for forming a phosphate conversion coating on a surface of a metallic substrate using a phosphate conversion coating composition, the improvement being the inclusion of a water-soluble substituted hydroxylamine or salt thereof in said phosphate conversion coating composition, wherein said water-soluble substituted hydroxylamine contains a N—O moiety and at least one C1 to C6 alkyl group substituted on the N atom, the O atom, or both the N atom and O atom.
A method of preparing a manganese phosphate conversion coating composition comprising dissolving a manganese compound in an aqueous solution comprised of phosphoric acid in the presence of a water-soluble alkyl substituted hydroxylamine or salt thereof.
Dependencies are inferred from the claim text.