Coatings for metals based on functionalized block copolymers

Abstract

A permanent, flexible coating for protecting and lubricating metal that is formed into articles by single step or multiple step bending or stamping deformation is disclosed. The coating comprises a block copolymer which is formed from selective hydrogenation of an (A-B)n-A or (A-B)n block copolymer. Monomers containing functional groups, preferably monocarboxylic or polycarboxylic acid compounds or their derivatives, are grafted onto the selectively hydrogenated block copolymer in an amount sufficient to improve adhesion of the polymer to the metal. The functionalized block copolymer can be crosslinked to improve resistance of the coating to organic solvents.

What is claimed is: 
     
       1. A process for making a polymer coated metal article, comprising the steps of: coating at least one surface of a metal by applying a solution consisting essentially of a solvent and a selectively hydrogenated and functionalized block copolymer having an (A-B) n  -A configuration, wherein:   each A component of the block copolymer is predominately a polymerized vinyl aromatic hydrocarbon;   each B component of the block copolymer prior to hydrogenation is predominately a polymerized conjugated diene;   each A component is hydrogenated to an unsaturation that is above 50% of the original unsaturation;   each B component is hydrogenated to an unsaturation that is below 10% of the original unsaturation;   n is 1; and   maleic anhydride is grafted to the block copolymer in an amount sufficient to improve adhesion of the block copolymer to the metal; and   stamping the coated metal into a finished article.   
     
     
       2. The process of claim 1, wherein the A component is formed from styrene monomer and the B component is formed from either 1,3-butadiene monomer or isoprene monomer. 
     
     
       3. The process of claim 2, wherein the amount of the maleic anhydride is between about 0.2 and 5 percent by weight of the total weight of the block copolymer. 
     
     
       4. The process of claim 3, wherein the block copolymer is applied to the metal from a solution of the block copolymer in a blend of toluene and isopropylalcohol. 
     
     
       5. The process of claim 1, further comprising the step of crosslinking the functionalized block copolymer to improve resistance to organic solvents. 
     
     
       6. The process of claim 5, wherein the A component is formed from styrene monomer and the B component is formed from either 1,3-butadiene monomer or isoprene monomer. 
     
     
       7. The process of claim 6, wherein the amount of the maleic anhydride is between about 0.2 and 5 percent by weight of the block copolymer prior to the crosslinking step. 
     
     
       8. The process of claim 7, wherein the block copolymer is crosslinked with an aminoplast resin.