Continuous coil pretreatment process

Abstract

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 . (canceled) 
     
     
         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.   
     
     
         23 . A continuous coil pretreatment process comprising:
 a) cleaning a surface of an aluminum sheet or a coil; then   b) etching the surface of the aluminum sheet or the coil by spraying the surface of the aluminum sheet or the coil with an acidic etching solution comprising up to 8 vol. % of sulfuric acid for a period of about 5 seconds to about 15 seconds, wherein the acidic etching solution in contact with the surface of the aluminum sheet or the coil is controlled by replacing or replenishing the acidic etching solution when a combined concentration of aluminum and magnesium ions exceeds 1,000 ppm; then   c) rinsing the surface of the aluminum sheet or the coil with deionized water; then   d) applying to the surface of the aluminum sheet or the coil a solution comprising a vinylphosphonic acid-acrylic acid (VPA-AA) copolymer; then   e) rinsing the surface of the aluminum sheet or the coil by (i) spraying the surface of the aluminum sheet or the coil with deionized water in a spray direction opposite a feed direction of the aluminum sheet or the coil as it advances in the continuous coil pretreatment process, (ii) providing a water dam at an entry point of an exit squeegee roll, and (iii) continuously rinsing a surface of the exit squeegee roll; and then   f) drying the surface of the aluminum sheet or the coil.   
     
     
         24 . The process of  claim 23 , wherein a concentration of the vinylphosphonic acid-acrylic acid (VPA-AA) copolymer in the solution comprising the vinylphosphonic acid-acrylic acid (VPA-AA) copolymer is about 0.4 wt. % to about 10 wt. %. 
     
     
         25 . The process of  claim 23 , wherein a concentration of the vinylphosphonic acid-acrylic acid (VPA-AA) copolymer in the solution comprising the vinylphosphonic acid-acrylic acid (VPA-AA) copolymer is about 0.6 wt. % to about 5 wt. %. 
     
     
         26 . The process of  claim 23 , wherein a concentration of the vinylphosphonic acid-acrylic acid (VPA-AA) copolymer in the solution comprising the vinylphosphonic acid-acrylic acid (VPA-AA) copolymer is about 0.7 wt. % to about 3 wt. %. 
     
     
         27 . The process of  claim 23 , wherein a concentration of the vinylphosphonic acid-acrylic acid (VPA-AA) copolymer in the solution comprising the vinylphosphonic acid-acrylic acid (VPA-AA) copolymer is about 0.8 wt. % to about 1.0 wt. %. 
     
     
         28 . The process of  claim 23 , wherein the acidic etching solution further comprises hydrofluoric acid, nitric acid, phosphoric acid, or mixtures thereof. 
     
     
         29 . The process of  claim 23 , wherein the acidic etching solution further comprises hydrofluoric acid. 
     
     
         30 . The process of  claim 23 , wherein the deionized water in step (c) has a conductivity of less than or equal to 25 uS/cm. 
     
     
         31 . The process of  claim 23 , wherein the aluminum sheet or the coil is made from an aluminum alloy selected from the group consisting of 5XXX and 6XXX alloys. 
     
     
         32 . The process of  claim 23 , wherein the aluminum sheet or the coil is made from an aluminum alloy selected from the group consisting of AA5754, AA5182, AA6451, AA6111 and AA6014 alloys. 
     
     
         33 . The process of  claim 23 , wherein the cleaning in step (a) comprises applying a cleaner comprising water. 
     
     
         34 . The process of  claim 33 , wherein the cleaner further comprises an acid, an alkali, a surfactant, a detergent, or mixtures thereof. 
     
     
         35 . The process of  claim 23 , wherein the applying in step (d) is performed by immersing the aluminum sheet or the coil in the solution comprising the vinylphosphonic acid-acrylic acid (VPA-AA) copolymer. 
     
     
         36 . The process of  claim 23 , wherein the applying in step (d) is performed by spraying the aluminum sheet or the coil with the solution comprising the vinylphosphonic acid-acrylic acid (VPA-AA) copolymer. 
     
     
         37 . A continuous coil pretreatment process comprising:
 a) cleaning a surface of an aluminum sheet or a coil by water spray impingement; then   b) etching the surface of the aluminum sheet or the coil by spraying the surface of the aluminum sheet or the coil with an acidic etching solution comprising about 1.5 to about 10 vol. % of sulfuric acid for a period of about 5 seconds to about 15 seconds, wherein the acidic etching solution in contact with the surface of the aluminum sheet or the coil is controlled to maintain a concentration of aluminum and magnesium ions not exceeding 1,000 ppm and wherein the acidic etching solution is replaced or replenished when the concentration of aluminum and magnesium ions exceeds 1,000 ppm; then   c) rinsing the surface of the aluminum sheet or the coil with deionized water at a temperature of about 37° C. to about 65° C.; then   d) applying to the surface of the aluminum sheet or the coil a solution comprising a vinylphosphonic acid-acrylic acid (VPA-AA) copolymer for a period of about 5 seconds to about 20 seconds, wherein a concentration of the vinylphosphonic acid-acrylic acid (VPA-AA) in the solution comprising the vinylphosphonic acid-acrylic acid (VPA-AA) copolymer is about 0.8 wt. % to 1.0 wt. %; then   e) rinsing the surface of the aluminum sheet or the coil either immediately after step (d) or with a delay of about 1 second to about 5 seconds, wherein the rinsing comprises (i) spraying the surface of the aluminum sheet or coil with deionized water in a spray direction opposite a feed direction of the aluminum sheet or the coil as it advances in the continuous coil pretreatment process, (ii) providing a water dam at an entry point of an exit squeegee roll, and (iii) continuously rinsing a surface of the exit squeegee roll; and then   f) drying the surface of the aluminum sheet or the coil.   
     
     
         38 . The process of  claim 37 , wherein the acidic etching solution is combined with a surfactant additive or an accelerator. 
     
     
         39 . The process of  claim 23 , wherein the acidic etching solution in contact with the surface of the aluminum sheet or the coil in step (b) is controlled to maintain the combined concentration of aluminum and magnesium ions to a range from 800 ppm to less than 1,000 ppm. 
     
     
         40 . The process of  claim 37 , wherein the acidic etching solution in contact with the surface of the aluminum sheet or the coil in step (b) is controlled to maintain the concentration of aluminum and magnesium ions to a range from 800 ppm to less than 1,000 ppm. 
     
     
         41 . The process of  claim 37 , wherein the acidic etching solution in contact with the surface of the aluminum sheet or the coil in step (b) comprises about 1.5 to about 8 vol. % of sulfuric acid.