Coating solution for metal surfaces
First Claim
1. An aluminum surface having a uniformly colorless and clear coating which is free of boron and phosphate and is capable of turning light golden brown to purple in color when heated at a temperature of 900°
- F. for 5 minutes, but which resists blackening for at least 5 minutes when heated in water having a temperature within the range of about 140°
F. to about 170°
F., said coated aluminum surface having been obtained by contacting such aluminum surface with an acidic aqueous coating solution having a pH within the range of about 3.0 to about 5.0 and consisting essentially of at least about 0.5×
10-3 moles/liter of zirconium or hafnium or a mixture thereof, at least about 0.025×
10-3 moles/liter of a polyhydroxy compound having no more than 7 carbon atoms, and at least sufficient fluoride to combine with and form a soluble complex with all of the zirconium and hafnium present in the solution, wherein said polyhydroxy compound is selected from the group consisting of gluconic acid, a salt of gluconic acid, sorbitol, mannitol, dextrose, ethylene glycol, glycerine, and glucoheptonate.
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Accused Products
Abstract
An acidic aqueous coating solution for forming a coating on an aluminum surface which is corrosion resistant and to which overlying coatings adhere excellently. The coating solution contains a zirconium and/or hafnium compound, a fluoride compound, and a polyhydroxy compound having no more than 7 carbon atoms. The coating solution is capable of forming on an aluminum surface a uniformly colorless and clear coating so that the coated surface has the appearance of the underlying metal surface, that is, the coating can be formed without changing the appearance of the metal surface. When coating a bright shiny aluminum surface, there can be produced a coated surface having a uniformly bright shiny appearance which is maintained even after the coated surface is subjected to boiling water. Such surface is capable of undergoing the "muffle test" to confirm the presence of the clear and colorless coating.
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Citations
64 Claims
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1. An aluminum surface having a uniformly colorless and clear coating which is free of boron and phosphate and is capable of turning light golden brown to purple in color when heated at a temperature of 900°
- F. for 5 minutes, but which resists blackening for at least 5 minutes when heated in water having a temperature within the range of about 140°
F. to about 170°
F., said coated aluminum surface having been obtained by contacting such aluminum surface with an acidic aqueous coating solution having a pH within the range of about 3.0 to about 5.0 and consisting essentially of at least about 0.5×
10-3 moles/liter of zirconium or hafnium or a mixture thereof, at least about 0.025×
10-3 moles/liter of a polyhydroxy compound having no more than 7 carbon atoms, and at least sufficient fluoride to combine with and form a soluble complex with all of the zirconium and hafnium present in the solution, wherein said polyhydroxy compound is selected from the group consisting of gluconic acid, a salt of gluconic acid, sorbitol, mannitol, dextrose, ethylene glycol, glycerine, and glucoheptonate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 61, 63)
- F. for 5 minutes, but which resists blackening for at least 5 minutes when heated in water having a temperature within the range of about 140°
-
28. A continuous process for coating aluminum surfaces having a bright shiny appearance which comprises contacting such surfaces with an acidic aqueous coating solution having a pH within the range of about 3.0 to about 5.0 and consisting essentially of at least about 0.5×
- 10-3 moles/liter of zirconium or hafnium or a mixture thereof, at least about 0.025×
10-3 moles/liter of a polyhydroxy compound having no more than 7 carbon atoms, and sufficient fluoride to combine with and form a soluble complex with all of the zirconium and hafnium present in the solution and provide uncomplexed available fluoride, said solution being free of boron and phosphate, and replenishing said solution as necessary with aqueous replenishing concentrate so as to maintain such concentrations, said replenishing concentrate also being free of boron and phosphate, so as to continuously produce aluminum surfaces having uniformly colorless and clear coatings which are capable of turning light golden brown to purple in color when heated at a temperature of 900°
F. for 5 minutes, but which resist blackening for at least 5 minutes when heated in water having a temperature within the range of about 140°
F. to about 170°
F., wherein said polyhydroxy compound is selected from the group consisting of gluconic acid, a salt of gluconic acid, sorbitol, mannitol, dextrose, ethylene glycol, glycerine and glucoheptonate. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 62, 64)
- 10-3 moles/liter of zirconium or hafnium or a mixture thereof, at least about 0.025×
-
55. A acidic aqueous coating solution having a pH within the range of about 3.0 to about 5.0 and consisting essentially of at least about 0.5×
- 10-3 moles/liter of zirconium or hafnium or a mixture thereof, at least about 0.025×
10-3 moles/liter of polyhydroxy compound having no more than 7 carbon atoms, and at least sufficient fluoride to combine with and form a soluble complex with all of the zirconium and hafnium present in the solution, said solution being free of boron and phosphate and capable of forming a uniformly colorless and clear coating on an aluminum surface which is capable of turning light golden brown to purple in color when heated at a temperature of 900°
F. for about 5 minutes, but which resists blackening for at least 5 minutes when heated in water having a temperature within the range of about 140°
F. to about 170°
F., wherein said polyhydroxy compound is selected from the group consisting of gluconic acid, a salt of gluconic acid, sorbitol, mannitol, dextrose, ethylene glycol, glycerine, and glucoheptonate.
- 10-3 moles/liter of zirconium or hafnium or a mixture thereof, at least about 0.025×
-
56. An aqueous concentrate such that an aqueous coating solution containing about 0.5 to about 10 weight percent of the concentrate has a pH within the range of about 3.0 to about 5.0 and consists essentially of at least about 0.5×
- 10-3 moles/liter of zirconium or hafnium or a mixture thereof, at least about 0.025×
10-3 moles/liter of a polyhydroxy compound having no more than 7 carbon atoms, and at least sufficient fluoride to combine with and form a soluble complex with all of the zirconium and hafnium present in the solution, said coating solution being free of boron and phosphate and capable of forming a uniformly colorless and clear coating on a aluminum surface which is capable of turning light golden brown to purple in color when heated at a temperature of 900°
F. for 5 minutes, but which resists blackening for at least 5 minutes when heated in water having a temperature within the range of about 140°
F. to about 170°
F., wherein said polyhydroxy compound is selected from the group consisting of gluconic acid, a salt of gluconic acid, sorbitol, mannitol, dextrose, ethylene glycol, glycerine, and glucoheptonate.
- 10-3 moles/liter of zirconium or hafnium or a mixture thereof, at least about 0.025×
-
57. An aluminum surface having a uniformly colorless and clear coating which is free of boron and phosphate and is capable of turning light golden brown to purple in color when heated at a temperature of 900°
- F. for 5 minutes, but which resists blackening for at least 5 minutes when heated in water having a temperature within the range of about 140°
F. to about 170°
F., said coated aluminum surface having been obtained by contacting such aluminum surface with an acidic aqueous coating solution having a pH within the range of about 3.0 to about 5.0 and consisting essentially of at least about 0.5×
10-3 moles/liter of zirconium or hafnium or a mixture thereof, at least about 0.025×
10-3 moles/liter of a water soluble polyhydroxy compound having no more than 7 carbon atoms, and at least sufficient fluoride to combine with and form a soluble complex with all of the zirconium and hafnium present in the solution.
- F. for 5 minutes, but which resists blackening for at least 5 minutes when heated in water having a temperature within the range of about 140°
-
58. A continuous process for coating aluminum surfaces having a bright shiny appearance which comprises contacting such surfaces with an acidic aqueous coating solution having a pH within the range of about 3.0 to about 5.0 and consisting essentially of at least about 0.5×
- 10-3 moles/liter of zirconium or hafnium or a mixture thereof, at least about 0.025×
10-3 moles/liter of a water soluble polyhydroxy compound having no more than 7 carbon atoms, and sufficient fluoride to combine with and form a soluble complex with all of the zirconium and hafnium present in the solution and provide uncomplexed available fluoride, said solution being free of boron and phosphate, and replenishing said solution as necessary with aqueous replenishing concentrate so as to maintain such concentrations, said replenishing concentrate also being free of boron and phosphate, so as to continuously produce aluminum surfaces having uniformly colorless and clear coatings which are capable of turning light golden brown to purple in color when heated at a temperature of 900°
F. for 5 minutes, but which resist blackening for at least 5 minutes when heated in water having a temperature within the range of about 140°
F. to about 170°
F.
- 10-3 moles/liter of zirconium or hafnium or a mixture thereof, at least about 0.025×
-
59. An acidic aqueous coating solution having a pH within the range of about 3.0 to about 5.0 and consisting essentially of at least about 0.5×
- 10-3 moles/liter of zirconium and hafnium or a mixture thereof, at least about 0.025×
10-3 moles/liter of a water soluble polyhydroxy compound having no more than 7 carbon atoms, and at least sufficient fluoride to combine with and form a soluble complex with all of the zirconium and hafnium present in the solution, said solution being free of boron and phosphate and capable of forming a uniformly colorless and clear coating on an aluminum surface which is capable of turning light golden brown to purple in color when heated at a temperature of 900°
F. for about 5 minutes, but which resists blackening for at least 5 minutes when heated in water having a temperature within the range of about 140°
F. to about 170°
F.
- 10-3 moles/liter of zirconium and hafnium or a mixture thereof, at least about 0.025×
-
60. An aqueous concentrate such that an aqueous coating solution containing about 0.5 to about 10 weight percent of the concentrate has a pH within the range of about 3.0 to about 5.0 and consists essentially of at least about 0.5×
- 10-3 moles/liter of zirconium or hafnium or a mixture thereof, at least about 0.025×
10-3 moles/liter of a water soluble polyhydroxy compound having no more than 7 carbon atoms, and at least sufficient fluoride to combine with and form a soluble complex with all of the zirconium and hafnium present in the solution, said coating solution being free of boron and phosphate and capable of forming a uniformly colorless and clear coating on an aluminum surface which is capable of turning light golden brown to purple in color when heated at a temperature of 900°
F. for 5 minutes, but which resists blackening for at least 5 minutes when heated in water having a temperature within the range of about 140°
F. to about 170°
F.
- 10-3 moles/liter of zirconium or hafnium or a mixture thereof, at least about 0.025×
Specification