Method of making metal surfaces wettable
A method of treating a surface of a metal foil or sheet to make the surface wettable. The method comprises obtaining a metal foil or sheet having an oil-coated surface to be treated, applying a solution of phosphoric acid in a polar, non-aqueous, water-free solvent evenly to the surface at a rate of application in a range of at least 10 mg/ft 2 , the phosphoric acid being contained in the solution at a concentration such that the phosphoric acid contacts the surface in an amount of 0.5 to 2.0 mg/ft 2 ; and removing the solvent by either drying the surface or heating the foil or sheet at an elevated temperature above ambient to evaporate the oil from the surface to be treated with the proviso that the elevated temperature does not fall in the range between 130 to 240° C. The resulting foil has a wettable surface and can be used, for example, for coating with a layer of another material (e.g. polymer or adhesive) and achieve high peel strength.
1 . A method of treating a surface of a sheet of aluminum or an aluminum alloy to make the surface wettable, said method comprising:
applying a solution of phosphoric acid in a solvent to said surface, said solvent being selected from the group consisting of (a) a polar, non-aqueous, water-free solvent, and (b) a mixture of a polar, non-aqueous, water-free solvent and a volatile polar hydrocarbon solvent; and
removing said solvent by drying said surface at ambient temperature or by heating said surface at an elevated temperature above ambient, with the proviso that said elevated temperature does not fall in the range of 130 to 240° C.
2 . The method of claim 1 , wherein the phosphoric acid is contained in said solution at a concentration such that said phosphoric acid contacts said surface in an amount of 0.5 to 2.0 mg/ft 2 .
3 . The method of claim 2 , wherein said solution is applied to said surface in an amount of at least 10 mg/ft 2 .
4 . The method of claim 1 , wherein the surface is a surface of an aluminum or aluminum alloy foil.
5 . The method of claim 1 , wherein the surface is a surface of an aluminum or aluminum sheet.
6 . The method of claim 1 , wherein said metal is an aluminum alloy of the AA1000 series.
7 . The method of claim 1 , wherein said metal is selected from the group consisting of AA1145 and AA1100.
8 . The method of claim 1 , wherein said elevated temperature is 130° C. or less.
9 . The method of claim 1 , wherein said elevated temperature is 240° C. or more.
10 . The method of claim 9 , wherein said elevated temperature is below 400° C.
11 . The method of claim 9 , wherein said elevated temperature is 280° C. or less.
12 . The method of claim 9 , wherein said heating is carried out at a temperature and for a time that retain a fully hard temper of said metal.
13 . The method of claim 9 , wherein said heating is carried out at a temperature and for a time that causes partial annealing of said metal.
14 . The method of claim 9 , wherein said heating is carried out at a temperature and for a time that produce a full O-temper of said metal.
15 . A metal foil or sheet having a wettable surface, produced by a process according to claim 1.