Rinsable metal pretreatment methods and compositions
Chromate-free and metal phosphate free treatments and compositions for applying a conversion or passivation coating for metals, more particularly, steel, zinc coated steel, and aluminum surfaces. The methods of the invention comprise contacting the requisite metal surface with a treatment composition comprising a member or members comprising one or more Group IV B elements, fluoride, and phosphonic acid or phosphonate. Optionally, a silane may be added as a treatment component.
1 . A method of coating a metal or metal alloy surface comprising contacting said surface with an effective amount of a chromate free aqueous treatment solution or dispersion comprising (a) a material or materials comprising one or more elements selected from Group IV B elements, (b) fluoride, (c) phosphonic acid or phosphonate.
2 . A method as recited in claim 1 , wherein said phosphonic acid or phosphonate (c) is selected from the group consisting of the formulas II, III, or IV, wherein formula II has the structure:
wherein R 1 is PO 3 X 2 or R 2 PO 3 X 2 wherein X 2 is a cation or H; R 2 is C 1 -C 5 alkylene and Z is a member selected from H, halo, C 1 -C 5 alkyl, NO 2 and COOH; formula III has the structure:
wherein X is independently chosen from a cation or H; and R 3 is C 1 -C 5 alkyl, C 1 -C 5 carboxyalkyl, C 1 -C 5 phosphonoalkyl, C 1 -C 5 siloxyalkyl, and C 1 -C 5 iminoalkyl or C 1 -C 5 phosphonoimino alkyl; and
wherein X is as defined above; R 4 and R 5 are independently chosen from H, C 1 -C 5 alkyl, C 1 -C 5 hydroxyalkyl, C 1 -C 5 phosphonoalkyl, with the proviso that R 4 and R 5 may, together as covalently linked, form a cyclic structure; R 6 may or may not be present, and when present is a C 1 -C 5 alkylene moiety; and Q is N or N oxide + .
3 . A method as recited in claim 2 wherein (a) comprises H 2 ZrF 6 and H 2 TiF 6 .
4 . A method as recited in claim 2 wherein said phosphonic acid or phosphonate (c) has the formula IV.
5 . A method as recited in claim 4 wherein said phosphonic acid or phosphonate (c) comprises linear EBO or cyclic EBO and mixtures thereof.
6 . A method as recited in claim 2 wherein said phosphonic acid or phosphonate (c) has the formula (II).
7 . A method as recited in claim 6 wherein said phosphonic acid and/or phosphonate (c) is a member or members selected from the group consisting of 4-bromobenzylphosphonic acid, 4-tertbutylbenzylphosphonic acid, phenylphosphonic acid, 4-hydroxybenzylphosphonic acid, 4-nitrobenzylphosphonic acid, 4-methylbenzylphosphonic acid, 4-carboxybenzylphosphonic acid and 4-bromobenzyl phosphonate ethyl ester.
8 . A method as recited in claim 2 wherein said phosphonic acid or phosphonate (c) has the formula III.
9 . A method as recited in claim 8 wherein said phosphonic and/or phosphonate (c) is a member or members selected from the group consisting of 2-carboxyethylphosphonic acid, trihydroxysilylpropyl phosphonate; 1,2,-diethylenediphosphonic acid, iminobis (methylphosphonic acid) and tertbutylphosphonic acid.
10 . Acidic, aqueous composition or dispersion for forming a conversion or passivation coating on metallic surfaces, said composition being free of chromate and comprising a) material or materials comprising one or more elements selected from Group IV B elements, b) fluoride, and c) a phosphonic acid or phosphonate.
11 . Composition as recited in claim 10 wherein said phosphonic acid or phosphonate (c) is selected from the groups consisting of the formulas II, III, or IV wherein formula II has the structure:
wherein R 1 is PO 3 X 2 or R 2 PO 3 X 2 wherein X 2 is a cation or H; R 2 is C 1 -C 5 alkylene and Z is a member selected from H, halo, C 1 -C 5 alkyl, NO 2 , and COOH; formula III has the structure:
wherein X is independently chosen from a cation or H; and R 3 is C 1 -C 5 alkyl, C 1 -C 5 carboxyalkyl, C 1 -C 5 phosphonoalkyl, C 1 -C 5 siloxyalkyl, C 1 -C 5 iminoalkyl and C 1 -C 5 phosphonoiminoalkyl; and formula IV has the structure
wherein X is as defined above; R 4 and R 5 are independently chosen from H, C 1 -C 5 alkyl, C 1 -C 5 hydroxyalkyl, C 1 -C 5 phosphonoalkyl, with the proviso that R 4 and R 5 may, together as covalently linked, form a cyclic structure, R 6 may or may not be present, and when present is C 1 -C 5 alkylene moiety, and Q is N or N oxide.
12 . A composition as recited in claim 11 wherein (a) comprises H 2 ZrF 6 and H 2 TiF 6 .
13 . A composition as recited in claim 11 wherein said phosphonic acid or phosphate (c) is selected from formula II.
14 . A composition as recited in claim 12 wherein said phosphonic acid or phosphonate (c) is selected from the group consisting of 4-bromobenzylphosphonic acid, 4-tertbutylbenzylphosphonic acid, phenylphosphonic acid, 4-hydroxybenzylphosphonic acid, 4-nitrobenzylphosphonic acid, 4-methylbenzylphosphonic acid, 4-carboxybenzylphosphonic acid and 4-bromobenzyl phosphonate ethyl ester.
15 . A composition as recited in claim 11 wherein said phosphonic acid or phosphonate (c) is selected from formula III.
16 . A composition as recited in claim 14 wherein said phosphonic acid or phosphonate (c) is selected from the group consisting of 2-carboxyethylphosphonic acid, trihydroxysilylpropyl phosphonate; 1,2,-diethylenediphosphonic acid, iminobis (methylphosphonic acid) and tertbutylphosphonic acid.
17 . A composition as recited in claim 11 wherein said phosphonic acid or phosphonate is selected from formula IV.
18 . A composition as recited in claim 17 wherein said phosphonic acid or phosphonate (c) comprises linear EBO or cyclic EBO or mixtures thereof.
19 . Composition for forming a conversion or passivating coating on metallic surfaces, said composition comprising an acidic aqueous solution or dispersion of
1) H 2 ZrF 6 in an amount of 0.01-40 wt %;
2) H 2 TiF 6 in an amount of 0.01-40 wt %;
3) a phosphonic acid or phosphonate selected from the formula II, III, or IV; said phosphonic acid or phosphonate 3) being present in an amount of about 0.01-50 wt %, pH adjustment agent, 4) and silane 5) in an amount of about 0.00-20 wt %, remainder water to equal 100 wt %, said formula II having the structure wherein
wherein R 1 is PO 3 X 2 or R 2 PO 3 X 2 wherein X 2 is a cation or H; R 2 is C 1 -C 5 alkylene and Z is a member selected from H, halo, C 1 -C 5 alkyl, NO 2 , and COOH; said formula III having the structure:
wherein X is independently chosen from a cation or H; and R 3 is C 1 -C 5 alkyl, C 1 -C 5 carboxyalkyl, C 1 -C 5 phosphonoalkyl, C 1 -C 5 siloxyalkyl, and C 1 -C 5 iminoalkyl or C 1 -C 5 phosphonoimino alkyl; and
wherein X is as defined above; R 4 and R 5 are independently chosen from H, C 1 -C 5 alkyl, C 1 -C 5 hydroxyalkyl, C 1 -C 5 phosphonoalkyl, with the proviso that R 4 and R 5 may, together as covalently linked, form a cyclic structure, R 6 may or may not be present and when present is C 1 -C 5 alkylene, and Q is N or N oxide.
20 . A composition as recited in claim 19 wherein said phosphonic acid or phosphonate has the formula IV.
21 . A composition as recited in claim 19 wherein said phosphonic acid or phosphonate is linear EBO, cyclic EBO, or mixtures thereof.