Production of stain resistant, clear, sealed anodized films

Claim 2

IN A PROCESS OF SEALING AN ANODIZED ALUMINUM COATING IN WHICH SAID COATING IS CONTACTED WITH A FIRST SOLUTION CONTAINING TUNGSTATE AND CHROMATE IONS SO AS TO PARTIALLY SEAL SAID ANODIZED COATING, THE IMPROVEMENT WHICH COMPRISES: CONTACTING THE ANODIZED COATING WHICH HAS BEEN CONTACTED WITH SAID FIRST SOLUTION AFTER IT HAS BEEN REMOVED FROM SAID FIRST SOLUTION WITH A FURTHER SOLUTION CONTAINING FROM ABOUT 0.1% TO ABOUT 10% BY WEIGHT OF A SOLUBLE SALT OF A METAL SELECTED FROM THE GROUP CONSISTING OF NICKEL AND COBALT AND OF A WEAK ACID AT A TEMPERATURE OF FROM ABOUT 150*F. TO IMMEDIATELY BELOW THE BOILING POINT OF SAID SOLUTION FOR A PERIOD SUFFICIENT TO FURTHER SEAL SAID W ANODEIZED COATING IN ORDER TO RENDER SAID ANODIZED COATING SUBSTANTIALLY STAIN RESISTANT.

Claim 3

A process as claimed in claim 1 wherein: said furthEr solution consists essentially of water and said salt and said weak acid is an acid selected from a group consisting of boric, citric, formic and acetic acids.

Claim 4

A process as claimed in claim 1 wherein: said further solution consists essentially of water, said salt and a buffering compound, and said weak acid is an acid selected from a group consisting of boric, citric, formic and acetic acids, and said buffering compound is a compound selected from the group consisting of boric acid, citric acid, formic acid and acetic acid and ammonium and alkali metal salts of such acids.

Claim 5

A process as claimed in claim 1 wherein: said further solution contacts said anodized coating for a period of from about 1 to about 20 minutes and has a pH of from about 4.5 to about 8.

Claim 6

A process as claimed in claim 1 wherein: said first solution consists essentially of water and from about 0.5 to about 10% by weight of a soluble tungstate salt, from about 0.1 to about 5% by weight chromic oxide present as chromic acid or as a soluble chromate salt, has a pH of from about 4.5 to about 8 and is in contact with said anodized coating for a period of from about 1 to about 20 minutes at a temperature of from about 130*F. to immediately below the boiling point of said solution, said further solution is a solution selected from the group consisting of (1) aqueous solutions consisting essentially of said salt and of (2) buffered aqueous solutions consisting essentially of said salt and a buffering compound, said weak acid being selected from the group consisting of boric, citric, formic and acetic acids, said buffering compound being selected from the group consisting of boric acid, citric acid, formic acid and acetic acid and ammonium and alkali metal salts of such acids, said further solution having a pH of from about 4.5 to about 7 and contacting said anodized coating for a period of from about 1 to about 20 minutes.

Claim 7

A process as claimed in claim 5 wherein: the pH of said further solution is from about 5.5 to about 6.5.

Claim 8

A process as claimed in claim 5 wherein: said first solution includes a wetting agent serving to facilitate penetration of said first solution into said anodizedcoating.

Claim 9

A process as claimed in claim 5 wherein: said further solution includes a wetting agent serving to facilitate penetration of said further solution into said anodized coating.

Claim 10

A process as claimed in claim 5 wherein: both of said first and said further solutions include a wetting agent serving to facilitate penetration of said solutions into said anodized coating.

Claim 11

An anodized, sealed aluminum oxide coating produced by the process of claim 5.

Claim 12

A process for sealing an anodized aluminum coating which comprises: contacting said coating after it has been anodized and before it has been further sealed for a period of from about 1 minute to about 20 minutes with a first solution containing essentially water and from about 0.1% to about 5% by weight chromic oxide present as a compound selected from the group consisting of chromic acid and soluble chromate salts and from about 0.5% to about 10% by weight of a soluble tungstate salt, said solution having a pH of from about 4.5 to about 8.0 and being at a temperature of from about 130*F. to immediately below the boiling point of said solution, and thereafter directly contacting said anodized coating for a period of from about 1 to about 20 minutes with a further solution selected from the group consisting of (1) solutions consisting essentially of water and from about 0.1% to about 10% by weight of a salt of a metal selected from the group consisting of nickel and cobalt and of an acid selected from the group consisting of boric, citric, formic and acetic acids and (2) solutions consisting essentially of water and from about 0.1% to about 10% by weight of a salt of a metal selected from the group consisting of nickel and cobalt and of an acid selected from the group consisting of boric, citric, formic and acetic acids and of a buffering compound selected from the group consisting essentially of boric, citric, formic and acetic acids and ammonium and alkali metal salts of such acids, said further solution having a pH of from about 4.5 to about 8 and being at a temperature of from about 150*F. to immediately below the boiling point of said solution.

Claim 13

A process for sealing an anodized aluminum coating which comprises: contacting said coating after it has been anodized and before it has been further sealed for a period of from about 1 minute to about 20 minutes with a first solution containing essentially water and from about 0.1% to about 5% by weight chromic oxide present as a compound selected from the group consisting of chromic acid and soluble chromate salts and from about 0.5% to about 10% by weight of a soluble tungstate salt, said solution having a pH of from about 4.5 to about 8.0 and being at a temperature of from about 130*F. to immediately below the boiling point of said solution, and thereafter directly contacting said anodized coating for a period of from about 1 to about 20 minutes with a further solution selected from the group consisting of (1) solutions consisting essentially of water and from about 0.1% to about 10% by weight of a salt of a metal selected from the group consisting of nickel and cobalt and of an acid selected from the group consisting of boric, citric, formic and acetic acids and (2) solutions consisting essentially of water and from about 0.1% to about 10% by weight of a salt of a metal selected from the group consisting of nickel and cobalt and of an acid selected from the group consisting of boric, citric, formic and acetic acids and of a buffering compound selected from the group consisting essentially of boric, citric, formic and acetic acids and ammonium and alkali metal salts of such acids, said further solution having a pH of from about 4.5 to about 8 and being at a temperature of from about 150*F. to immediately below the boiling point of said solution.

Claim 14

A process as claimed in claim 11 wherein: said further solution has a pH of from about 5.5 to about 6.5.

Claim 15

A process as claimed in claim 11 wherein: said first solution includes a wetting agent serving to facilitate penetration of said first solution into said anodized coating.

Claim 16

A process as claimed in claim 11 wherein: said further solution includes a wetting agent serving to facilitate penetration of said further solution into said anodized coating.

Claim 17

A process as claimed in claim 11 wherein: both of said first and said further solutions include a wetting agent serving to facilitate penetration of said solutions into said anodized coating, said further solution has a pH of from about 5.5 to about 6.5.