Electrolytic passivating of tin plated steel surfaces

Abstract

An electrolyte composition for passifying tin plated steel wherein the essential ingredient consists of a mixture of organic hydroxyl acids and phenol organic acids; a method of passifying tin plate steel articles with the composition by electrolysis with a pH of about 7.0-10.0 and preferably a pH of 8.0-9.5; and providing the passified tin plated steel article produces by the method along with the passified articles having an appropriate paint thereon.

1 . A tin plated steel passificating composition wherein the essential ingredient consists of a mixture of organic hydroxyl acids and phenol organic acids. 
   
   
       2 . The composition of  claim 1  wherein the organic hydroxyl acid is selected from C 2 -C 6 hydroxyl acids. 
   
   
       3 . The composition of  claim 2  wherein the C 2 -C 6 hydroxyl acids are selected from the group consisting of hydroxyl acetic acid, D-gluconic acid, citric acid and lactic acid; and the phenol organic acids are selected from the group consisting of hydrolysable tannic acid, gallic acid and dihydroxy benzoic acid. 
   
   
       4 . The composition of  claim 3  wherein the composition is an electrolyte composition having a pH of 7.0 to 10.0 and preferably a pH of 8.0-9.5. 
   
   
       5 . A passified tin plated article which has been passified by a composition wherein the essential ingredient of the composition is selected from a mixture consisting of mixture of organic hydroxyl acids and phenol organic acids. 
   
   
       6 . The passified tin plated article  claim 6  wherein the organic hydroxyl acid is selected from C 2 -C 6 hydroxyl acids. 
   
   
       7 . The passified tin plated article  claim 6  wherein the C 2 -C 6 hydroxyl acids are selected from the group consisting of hydroxyl acetic acid, D-gluconic acid, citric acid and lactic acid; and the phenol organic acids are selected from the group consisting of hydrolysable tannic acid, gallic acid and dihydroxy benzoic acid. 
   
   
       8 . The passified tin plated article  claim 7  wherein the composition is an electrolyte composition having a pH of 7.0-10.0 and preferably a pH of 8.0-9.5. 
   
   
       9 . The passified tin plated steel article of  claim 8 , wherein the article has a layer of an appropriate paint to provide a paint protected zinc, zinc plated, or steel article that passes the ASTM-D3359 paint adhesion test. 
   
   
       10 . A method of preparing a passified tin plated steel article comprising electrolytically passifating a cleaned tin plated steel article with an electrolyte composition wherein the essential ingredient consists of a mixture of organic hydroxyl acids and phenol organic acids. 
   
   
       11 . The method of  claim 10  wherein the organic hydroxyl acid is selected from C 2 -C 6 hydroxyl acids. 
   
   
       12 . The method of  claim 11  wherein the C 2 -C 6  hydroxyl acids are selected from the group consisting of hydroxyl acetic acid, D-gluconic acid, citric acid and lactic acid; and the phenol organic acids are selected from the group consisting of hydrolysable tannic acid, gallic acid and dihydroxy benzoic acid. 
   
   
       13 . The method of  claim 12  wherein the electrolyte composition having a pH of 7.0-10.0 and preferably a pH of 8.0-9.5. 
   
   
       14 . The method of  claim 13 , comprising the further steps of drying the passified tin plated steel article, and painting the dried article to provide paint protected tin plated steel article that will pass the ASTM-D3359 paint adhesion test.