Coating solution for metal surfaces

Claim 2

An acidic aqueous coating solution having a pH within the range of about 3 to about 5 and consisting essentially of at least about 3 ppm of zirconium, fluoride in an amount of at least about 5 ppm and less than an amount which causes etching of an aluminum surface to the extent that the surface has a dull and frosty appearance and boric acid, a water soluble salt of boric acid or boric oxide in an amount such that the concentration of boron is at least about 10 ppm, wherein said solution is capable of forming on an aluminum surface having a bright and shiny appearance a coating, the coated surface having said bright and shiny appearance and resisting blackening after the coated surface is subjected to boiling water for a 15 minute period, and wherein said solution is free of hexavalent chromium, ferroand ferricyanide, and any materials which contain a transition element of the chromium subgroup of the Periodic Table.

Claim 3

A coating solution according to claim 1 wherein the amount of each of said fluoride and boron is no greater than about 200 ppm.

Claim 4

A coating solution according to claim 2 wherein the amount of zirconium is at least about 50 ppm, the amount of fluoride is at least about 75 ppm, and the amount of boron is no greater than about 125 ppm.

Claim 5

A coating solution according to claim 1, including also nitric acid.

Claim 6

A coating solution according to claim 4 wherein the source of said zirconium is ammonium fluozirconate.

Claim 7

A coating solution according to claim 1 including about 0.1 to about 0.4 g/l of K 2 ZrF 6 , about 10 to about 125 ppm of boron added as H 3 BO 3 and nitric acid in an amount such that the pH of the solution is within the range of about 3 to about 5.

Claim 8

A method for applying a uniformly clear and colorless coating on a bright shiny aluminum surface comprising contacting said surface with the coating solution defined in claim 1 and forming said coating to provide a bright shiny coated aluminum surface.

Claim 11

A method according to claim 8 wherein said solution includes nitric acid.

Claim 12

A method according to claim 8 wherein the amount of zirconium is at least about 50 ppm and the amount of fluoride is at least about 75 ppm.

Claim 13

A method according to claim 8 wherein said coating solution includes also at least about 10 ppm of boron.

Claim 14

A method according to claim 11 wherein said solution includes nitric acid.

Claim 15

A method according to claim 11 wherein the coating solution includes boric acid, a water soluble salt of boric acid or boric oxide.

Claim 16

A method according to claim 8 wherein the temperature of the coating solution is about 120°F to about 150°F.

Claim 17

A method according to claim 14 wherein said solution is sprayed on said surface.

Claim 18

A method according to claim 15 wherein said solution consists essentially of about 0.1 to about 0.4 g/l of K 2 ZrF 6 , about 10 to about 125 ppm of boron added as H 3 BO 3 and nitric acid.

Claim 19

A method according to claim 8 wherein said coating solution consists essentially of at least about 50 ppm of zirconium, about 75 to about 200 ppm of fluoride, about 10 to about 125 ppm of boron added as boric acid and nitric acid.

Claim 20

A method according to claim 17 wherein the source of said zirconium is ammonium fluozirconate.

Claim 21

A method according to claim 8 including adding fluoride to said solution to complex aluminum that is dissolved during coating formation.

Claim 22

A method according to claim 8 and including pasteurizing the surface having said coating thereon.

Claim 23

An acidic aqueous coating solution having a pH of about 3 to about 5 and consisting essentially of zirconium, fluoride, and boron, the amount of zirconium being at least about 3 ppm, the amount of fluoride being within the range of about 5 to about 200 ppm, and the amount of boron being within the range of about 10 to about 200 ppm, wherein said solution is capable of forming on an aluminum surface having a bright and shiny appearance a coating, the coated surface having said bright and shiny appearance and resisting blackening after the coated surface is subjected to boiling water for a 15-minute period, wherein said solution is free of hexavalent chromium, ferro- and ferricyanide and any materials which contain a transition element of the chromium subgroup of the Periodic Table.

Claim 24

An acidic aqueous coating solution having a pH of about 3 to about 5 and consisting essentially of zirconium, fluoride, and boron, the amount of zirconium being at least about 3 ppm, the amount of fluoride being within the range of about 5 to about 200 ppm, and the amount of boron being within the range of about 10 to about 200 ppm, wherein said solution is capable of forming on an aluminum surface having a bright and shiny appearance a coating, the coated surface having said bright and shiny appearance and resisting blackening after the coated surface is subjected to boiling water for a 15-minute period, wherein said solution is free of hexavalent chromium, ferro- and ferricyanide and any materials which contain a transition element of the chromium subgroup of the Periodic Table.

Claim 25

A coating solution according to claim 21 wherein the source of said boron is boric acid, a water soluble salt of boric acid or boric oxide.

Claim 26

A method for producing a coated aluminum surface having a bright and shiny appearance comprising spraying a bright shiny aluminum surface with the coating solution defined in claim 22 at a temperature within the range of about 120° to about 150°F.

Claim 27

A method for producing a coated aluminum surface having a bright and shiny appearance comprising spraying a bright shiny aluminum surface with the coating solution defined in claim 21 at a temperature within the range of about 120° to about 150°F.

Claim 28

An acidic aqueous coating solution consisting essentially of a complex fluoride of zirconium in an amount such that the concentration of zirconium is at least about 3 ppm and the amount of fluoride is at least about 5 ppm and less than an amount which causes etching of an aluminum surface to the extent that the surface has a dull and frosty appearance, about 10 to about 200 ppm of boron added as boric acid, a water soluble salt of boric acid, or boric oxide, and nitric acid in an amount such that the pH of the solution is within the range of about 3 to about 5, wherein said solution is capable of forming on an aluminum surface having a bright and shiny appearance a coating, the coated surface having said bright and shiny appearance and resisting blackening after the coated surface has been subjected to boiling water for a 15 minute period and wherein said solution is free of hexavalent chromium, ferro- and ferricyanide, and any materials which contain a transition element of the chromium subgroup of the Periodic Table.

Claim 29

An acidic aqueous coating solution consisting essentially of a complex fluoride of zirconium in an amount such that the concentration of zirconium is at least about 3 ppm and the amount of fluoride is at least about 5 ppm and less than an amount which causes etching of an aluminum surface to the extent that the surface has a dull and frosty appearance, about 10 to about 200 ppm of boron added as boric acid, a water soluble salt of boric acid, or boric oxide, and nitric acid in an amount such that the pH of the solution is within the range of about 3 to about 5, wherein said solution is capable of forming on an aluminum surface having a bright and shiny appearance a coating, the coated surface having said bright and shiny appearance and resisting blackening after the coated surface has been subjected to boiling water for a 15 minute period and wherein said solution is free of hexavalent chromium, ferro- and ferricyanide, and any materials which contain a transition element of the chromium subgroup of the Periodic Table.

Claim 30

A coating solution according to claim 25 wherein the amount of fluoride is no greater than about 200 ppm.

Claim 31

A coating solution according to claim 25 wherein the amount of zirconium is at least about 50 ppm, the amount of fluoride is at least about 75 ppm, and the amount of boron is no greater than about 125 ppm.

Claim 32

A method for producing a coated aluminum surface having a bright and shiny appearance comprising spraying a bright shiny aluminum surface with the coating solution defined in claim 25 at a temperature within the range of about 120° to about 150°F.

Claim 33

An acidic aqueous coating solution consisting essentially of a complex fluoride of zirconium, in an amount such that the concentrations of zirconium and fluoride are equal to the concentration of zirconium and fluoride in a solution containing about 0.1 to about 0.4 g/l of K 2 ZrF 6 , about 10 to about 125 ppm of boron added as boric acid, a water soluble salt of boric acid or boric oxide, and nitric acid in an amount such that the pH of the solution is within the range of about 3 to about 5, wherein said solution is capable of forming on an aluminum surface having a bright and shiny appearance a coating, the coated surface having said bright and shiny appearance and resisting blackening after the coated surface has been subjected to boiling water for a 15 minute period, and wherein said solution is free of hexavalent chromium, ferro- and ferricyanide and any materials which contain a transition element of the chromium subgroup of the Periodic Table.

Claim 34

An acidic aqueous coating solution consisting essentially of a complex fluoride of zirconium, in an amount such that the concentrations of zirconium and fluoride are equal to the concentration of zirconium and fluoride in a solution containing about 0.1 to about 0.4 g/l of K 2 ZrF 6 , about 10 to about 125 ppm of boron added as boric acid, a water soluble salt of boric acid or boric oxide, and nitric acid in an amount such that the pH of the solution is within the range of about 3 to about 5, wherein said solution is capable of forming on an aluminum surface having a bright and shiny appearance a coating, the coated surface having said bright and shiny appearance and resisting blackening after the coated surface has been subjected to boiling water for a 15 minute period, and wherein said solution is free of hexavalent chromium, ferro- and ferricyanide and any materials which contain a transition element of the chromium subgroup of the Periodic Table.