Color coating for aluminum products

Claim 2

The process of claim 2 in which the aluminum product is first cleansed of foreign substances adhering thereto, the aluminum surface is treated to free said oxides from adherence thereto, and thereafter said oxides are allowed to react with said acrylic emulsion and to form and deposit on said surface a thin coating of the colored material resulting from such reaction.

Claim 3

The process of claim 3 in which the reagent for freeing the oxides is a weak alkaline solution.

Claim 4

The process of claim 4 in which following the freeing of said oxides the surface is treated with a formulated aqueous solution containing about 1 to 2 percent sodium dichromate, about 0.1 to 0.2 percent sodium bifluoride, and about 5 to 10 percent of sulfuric acid.

Claim 5

The process of claim 3 in which the copolymer of said acrylic emulsion comprises about 41 to 44 parts by weight of alkyl acrylonitrile solids and about 2 to 5 parts by weight of alkyl acrylate and alkyl methacrylate solids, and iron oxide is employed to catalyze the reaction of the aluminum oxides with the acrylic emulsion. 7 the precess of claim 6 in which said coalescing aid is ethelyne glycol butyl ether.

Claim 6

The process of claim 6 in which said acrylonitrile is methacrylonitrile.

Claim 7

The process of claim 6 in which said copolymer comprises methacrylonitrile and methyl acrylate.

Claim 8

The process of claim 6 in which said copolymer comprises methacrylonitrile and methyl methacrylate.

Claim 9

The process of claim 6 in which said catalyst comprises about 0.01 to 0.3 percent by weight of the resin content of the acrylic emulsion.

Claim 10

A process for forming on aluminum products a thin clear selectively colored corrosion resistant film comprising: lightly etching the product with a solution containing about 5 percent sodium hydroxide at a temperature of about 150* to 170* F; rinsing the product in water to remove the sodium hydroxide solution; passivating the surface with a formulated aqueous acid solution comprising about 1 to 2 percent sodium dichromate, about 0.1 to 0.2 percent sodium bifluoride, and about 5 to 10 percent sulfuric acid at room temperature; rinsing the product in water to remove all traces of the acid solution; drying the surface; exposing the surface for a selected period from about 10 to 60 minutes to an aqueous acrylic emulsion containing about 41 to 44 parts by weight of methacrylonitrile, about 2 to 5 parts by weight of an alkyl acrylate or a methacrylate, about 1 to 9 parts by weight of a coalescing acryloid solvent, about 0.03 to 0.35 parts by weight of an anionic wetting agent, and about 0.003 to 2.00 parts by weight of catalytic iron oxide, maintained at a selected temperature between about 80* to 200* F. and a selected pH of between about 8.5 and 10.5; force drying the thin colored layer of acrylic emulsion adhering to the surface at a temperature between about 200* and 350* F; reexposing the surface to the same aqueous acrylic emulsion for from 2 to 30 seconds; and force drying the thin colorless protective layer of acrylic emulsion adhering to said colored layer at a temperature between about 200* and 350* F.

Claim 11

The process of claim 12 in which said alkyl acrylate is methyl acrylate and said methacrylate is methyl methacrylate.

Claim 12

The process of claim 13 in which the pH of the acrylic emulsion is adjusted by the addition thereto of an aliphatic amine having at least two carbon atoms in its molecule.

Claim 13

The process of claim 14 in which said amine is diethylamine, triethylamine, ethylenediamine or ethanolamine.

Claim 14

A product having an exposed aluminum surface, said surface being coated with a thin clear selectively colored layer the principal component of which is an adhering material resulting from the chemical reaction of aluminum oxide on said surface with a formulated acrylic emulsion comprising a copolymer of about 35 to 50 parts of one or more of the alkyl acrylonitriles and about 1 to 10 parts of one or more of the alkyl acrylates and alkyl methacrylates, about 1 to 9 parts of a coalescing aid, and about 0.036 to 0.24 parts of an anionic wetting agent in the presence of about 0.003 to 2.00 parts of catalytic iron oxide, said emulsion being maintained at a temperature between about 80* and 200* F. and a pH of between about 8.5 and 10.5.