CONTINUOUS COIL PRETREATMENT PROCESS
Described herein is a continuous coil pretreatment process used to treat the surface of an aluminum alloy sheet or coil for subsequent deposition of an acidic organophosphorus compound. The process can include applying a cleaner to a surface of an aluminum sheet or a coil; etching the surface of the aluminum sheet or the coil with an acidic solution; rinsing the surface of the aluminum sheet or the coil with deionized water; applying to the surface of the aluminum sheet or the coil a solution of an acidic organophosphorus compound; rinsing the surface of the aluminum sheet or the coil with deionized water; and drying the surface of the aluminum sheet or the coil.
1 . A continuous coil pretreatment process comprising:
a) applying a cleaner to a surface of an aluminum sheet or a coil;
b) etching the surface of the aluminum sheet or the coil with an acidic solution;
c) rinsing the surface of the aluminum sheet or the coil with deionized water;
d) applying to the surface of the aluminum sheet or the coil a solution of an acidic organophosphorus compound;
e) rinsing the surface of the aluminum sheet or the coil with deionized water; and,
f) drying the surface of the aluminum sheet or the coil.
2 . The process of claim 1 , wherein the acidic organophosphorus compound is a vinylphosphonic acid-acrylic acid copolymer.
3 . The process of claim 1 , wherein the acidic organophosphorus compound is A951.
4 . The process of claim 1 , wherein the concentration of the acidic organophosphorus compound is about 0.4 wt. % to about 10 wt. %.
5 . The process of claim 1 , wherein the concentration of the acidic organophosphorus compound is about 0.6 wt. % to about 5 wt. %.
6 . The process of claim 1 , wherein the concentration of the acidic organophosphorus compound is about 0.7 wt. % to about 3 wt. %.
7 . The process of claim 1 , wherein the concentration of the acidic organophosphorus compound is about 0.8 wt. % to about 1.0 wt. %.
8 . The process of claim 1 , wherein the acidic solution comprises sulfuric acid, sulfuric acid and hydrofluoric acid, nitric acid, phosphoric acid, or mixtures thereof.
9 . The process of claim 1 , wherein the acidic solution comprises sulfuric acid and hydrofluoric acid.
10 . The process of claim 1 , wherein the concentration of the acidic solution is about 2 vol. % to about 15 vol. %.
11 . The process of claim 1 , wherein the deionized water in step (c) has a conductivity of less than or equal to 25 uS/cm.
12 . The process of claim 1 , wherein the aluminum sheet or coil is made from an aluminum alloy selected from the group consisting of 1XXX, 2XXX, 3XXX, 4XXX, 5XXX, 6XXX and 7XXX alloys.
13 . The process of claim 1 , wherein the aluminum sheet or coil is made from an aluminum alloy selected from the group consisting of AA5754, AA5182, AA6451, AA6111 and AA6014 alloys.
14 . The process of claim 1 , wherein the cleaner comprises hot water.
15 . The process of claim 14 , wherein the cleaner further comprises an acid, an alkali, a surfactant, a detergent, or mixtures thereof.
16 . The process of claim 1 , wherein the applying in step (d) is performed by immersing the aluminum sheet or the coil in the solution of the acidic organophosphorus compound.
17 . The process of claim 1 , wherein the applying in step (d) is performed by spraying the aluminum sheet or the coil with the solution of the acidic organophosphorus compound.
18 . The process of claim 1 , wherein step (b) is performed by applying a spray of the acidic solution.
19 . The process of claim 1 , wherein the acidic solution in contact with the surface of the aluminum sheet or coil in step (b) comprises less than about 1000 ppm of aluminum ions and magnesium ions.
20 . The process of claim 1 , wherein the solution of the acidic organophosphorus compound in contact with the surface of the aluminum sheet or coil in step (d) comprises an aluminum ion content of no more than about 80 ppm.
21 . An aluminum sheet or coil treated with the process of claim 1 .
22 . A continuous coil pretreatment process comprising:
a) applying a cleaner to a surface of an aluminum sheet or a coil by hot water spray impingement;
b) etching the surface of the aluminum sheet or the coil with an acidic solution, optionally combined with surfactant additives or accelerators, at a temperature of from about 55° C. to about 85° C. for a period of about 5 to about 15 seconds;
c) rinsing the surface of the aluminum sheet or the coil with deionized water at a temperature of about 37° C. to about 70° C.;
d) applying to the surface of the aluminum sheet or the coil a solution of an acidic organophosphorus compound at a temperature of about 45° C. to about 85° C. for period of about 5 seconds to about 20 seconds;
e) rinsing the surface of the aluminum sheet or the coil with deionized water either immediately after application of the acidic organophosphorus compound or about 1 to about 5 seconds later; and,
f) drying the surface of the aluminum sheet or the coil.