Pretreatment Composition

Abstract

Disclosed is a method of treating a substrate, comprising contacting at least a portion of the substrate surface with a first composition comprising a lanthanide source and an oxidizing agent. A substrate obtainable by the methods also is disclosed.

We claim: 
     
         1 . A system for treating a substrate comprising:
 a first composition for contacting at least a portion of the substrate, the first composition comprising a lanthanide series element cation and an oxidizing agent.   
     
     
         2 . The system of  claim 1 , wherein the oxidizing agent is present in the first composition in an amount of 25 ppm to 25,000 ppm based on total weight of the first composition. 
     
     
         3 . The system of  claim 1 , wherein the lanthanide series element cation comprises cerium, praseodymium, or combinations thereof. 
     
     
         4 . The system of  claim 1 , wherein the lanthanide series element cation is present in the first composition in an amount of 50 ppm to 200 ppm (calculated as cation) based on total weight of the first conversion composition. 
     
     
         5 . The system of  claim 1 , further comprising a second composition for treating at least a portion of the substrate, the second composition comprising a Group IA metal cation. 
     
     
         6 . The system of  claim 5 , wherein the Group IA metal cation comprises lithium, sodium, potassium, or combinations thereof. 
     
     
         7 . The system of  claim 5 , wherein the Group IA metal cation is present in the second composition in an amount of 5 ppm to 30,000 ppm (as metal cation) based on a total weight of the second composition. 
     
     
         8 . The system of  claim 5 , wherein the second composition has a pH of 8 to 13. 
     
     
         9 . The system of  claim 1 , further comprising a third composition for treating at least a portion of the substrate, the second composition comprising a Group IVB metal cation. 
     
     
         10 . The system of  claim 9 , wherein the Group IVB metal cation comprises zirconium, titanium, or combinations thereof. 
     
     
         11 . The system of  claim 9 , wherein the Group IVB metal cation is present in the third composition in an amount of 110 ppm to 170 ppm (as metal cation) based on a total weight of the third composition. 
     
     
         12 . The system of  claim 9 , wherein the third composition has a pH of 4 to 5. 
     
     
         13 . The system of  claim 1 , wherein the system is substantially free of phosphate. 
     
     
         14 . A substrate treated with the system of  claim 1 . 
     
     
         15 . The substrate of  claim 14 , wherein the substrate treated with the system has at least a 5% decrease in scribe creep on the substrate surface compared to a substrate treated with a composition comprising zirconium as measured by CASS testing. 
     
     
         16 . The substrate of  claim 14 , wherein at least a portion of the substrate surface is sanded, and wherein the substrate treated with the system has at least a 55% decrease in scribe creep on the sanded substrate surface compared to a sanded substrate treated with a composition comprising zirconium as measured by filiform corrosion testing. 
     
     
         17 . The substrate of  claim 14 , wherein at least a portion of the substrate surface is sanded, and wherein the substrate treated with the system has at least a 78% decrease in scribe creep on the sanded substrate surface compared to a sanded substrate treated with a composition comprising zirconium as measured by ASTM G85 A2 corrosion testing. 
     
     
         18 . A substrate treated with the system of  claim 5 . 
     
     
         19 . The substrate of  claim 18 , wherein the substrate treated with the system has at least a 25% decrease in scribe creep on the substrate surface compared to a substrate treated with a composition comprising zirconium as measured by ASTM G85 A2 testing. 
     
     
         20 . The substrate treated with the system of  claim 9 . 
     
     
         21 . The substrate of  claim 20 , wherein the substrate treated with the system has at least one of the following: a 13% decrease in scribe creep on the substrate surface compared to a substrate treated with a composition comprising a lanthanide series element cation or a Group IVB metal cation but not both as measured by CASS testing; a 47% decrease in scribe creep on the substrate surface compared to a substrate treated with a composition comprising a lanthanide series element cation or a Group IVB metal cation but not both as measured by SAE J2635; and/or at least a 42% increase in crosshatch adhesion compared to a substrate treated with a composition comprising a lanthanide series element cation or a Group IVB metal cation but not both. 
     
     
         22 . A method of treating a substrate comprising:
 contacting at least a portion of the substrate surface with a first composition comprising a lanthanide series element cation and an oxidizing agent.   
     
     
         23 . The method of  claim 22 , wherein the substrate surface is contacted with the first composition to result in a level of the lanthanide series element cation on the contacted substrate surface of at least 100 counts greater than on a surface of a substrate that is not contacted with the first composition as measured by X-ray fluorescence (measured using X-Met 7500, Oxford Instruments; operating parameters 60 second timed assay, 15Kv, 45 μA, filter 3, T(p)=1.5 μs). 
     
     
         24 . The method of  claim 22 , further comprising contacting at least a portion of the substrate surface with a second composition comprising a Group IA metal cation and/or a Group IVB metal cation. 
     
     
         25 . The method of  claim 24 , wherein the contacting with the first composition occurs prior to the contacting with the second composition. 
     
     
         26 . The method of  claim 24 , wherein the contacting with the second composition occurs prior to the contacting with the first composition. 
     
     
         27 . The method of  claim 22 , wherein the contacting with the first composition is 15 seconds to 4 minutes. 
     
     
         28 . The method of  claim 22 , further comprising heating the substrate for 15 minutes to 30 minutes at a temperature of 110° C. to 232° C. 
     
     
         29 . A substrate treated according to the method of  claim 28 , wherein the substrate has a b* value of less than 3.09 (spectral component excluded, 25 mm aperture).