Water based primer compositions

Abstract

The subject invention pertains to an aqueous primer for use on metal surfaces to which a composite or a metal adherend is bonded. The primer composition includes an aqueous dispersion of: (a) at least one thermosetting resin curable at an elevated temperature; (b) at least one organosilane, each said organosilane containing at least one hydrolyzable group; and (c) a curing agent. The aqueous primer composition contains substantially no volatile organic solvent, is environmentally superior to solvent-based primers, is storage stable, exhibits excellent solvent resistance and performs without loss of physical properties.

What is claimed is:  
     
         1 . A process for adhering a first metal to a second adherend, comprising: 
 (a) applying to said first metal a primer composition comprising an aqueous dispersion of: (i) at least one thermosetting resin curable at an elevated temperature; (ii) at least one organosilane, each said organosilane containing at least one hydrolyzable group; and (iii) a curing agent;    (b) applying a thermosetting adhesive between the primed surface of said first metal and said second adherend; and    (c) applying heat and pressure sufficient to cure said thermosetting adhesive.    
     
     
         2 . The process of  claim 1 , further comprising the step of curing said primer composition to prime a surface of said first metal prior to applying said thermosetting adhesive.  
     
     
         3 . The process of  claim 1 , wherein said primer is applied to said first metal surface in an amount sufficient to form a primer coating from about 0.0001 to about 0.005 inch in thickness after curing.  
     
     
         4 . The process of  claim 3 , wherein said primer is applied to said first metal surface in an amount sufficient to form a primer coating from about 0.0001 to about 0.0005 inch in thickness after curing.  
     
     
         5 . The process of  claim 4 , wherein said primer is applied to said first metal surface in an amount sufficient to form a primer coating from about 0.00015 to about 0.0003 inch in thickness upon curing.  
     
     
         6 . A process for preparing a composite article comprising a metal article and a layer of crosslinkable resin bonded thereto comprising: 
 (a) applying to said metal article a primer composition, comprising an aqueous dispersion of: (i) at least one thermosetting resin curable at an elevated temperature; (ii) at least one organosilane, each said organosilane containing at least one hydrolyzable group; and (iii) a curing agent;    (b) applying a crosslinkable resin to said primed surface of said metal article; and    (c) curing said crosslinkable resin.    
     
     
         7 . The process of  claim 6 , further comprising the step of curing said primer composition to form a primed metal surface of said metal article.  
     
     
         8 . The process of  claim 6 , wherein said primer is applied to said metal article in an amount sufficient to form a primer coating from about 0.0001 to about 0.005 inch in thickness upon curing.  
     
     
         9 . The process of  claim 8 , wherein said primer is applied to said metal article in an amount sufficient to form a primer coating from about 0.0001 to about 0.0005 inch in thickness upon curing.  
     
     
         10 . The process of  claim 9 , wherein said primer is applied to said metal article in an amount sufficient to form a primer coating from about 0.00015 to about 0.0003 inch in thickness upon curing.  
     
     
         11 . The process of  claim 6 , wherein said crosslinkable resin is a thermosetting resin.  
     
     
         12 . The process of  claim 11 , wherein said crosslinkable resin is applied as a sheet, a liquid or a paste.  
     
     
         13 . The process of  claim 12 , wherein said liquid is a paint.  
     
     
         14 . The process of  claim 6 , wherein said thermosetting resin further incorporates fibrous reinforcement.  
     
     
         15 . A process for priming a metal surface comprising the steps of: 
 (a) coating the metal surface with a primer composition comprising an aqueous dispersion of: (i) at least one thermosetting resin curable at an elevated temperature; (ii) at least one organosilane, each said organosilane containing at least one hydrolyzable group; and (iii) a curing agent; and    (b) heating the primer composition to a temperature sufficiently high to crosslink the primer composition to form an adherend coating on the metal surface.    
     
     
         16 . The process of  claim 15 , wherein said primer is applied to said metal article in an amount sufficient to form a primer coating from about 0.0001 to about 0.005 inch in thickness upon curing.  
     
     
         17 . The process of  claim 15 , wherein said primer is applied to said metal article in an amount sufficient to form a primer coating from about 0.0001 to about 0.0005 inch in thickness upon curing.  
     
     
         18 . The process of  claim 17 , wherein said primer is applied to said metal article in an amount sufficient to form a primer coating from about 0.00015 to about 0.0003 inch in thickness upon curing.  
     
     
         19 . The process of  claim 15 , further comprising the step of roughening said metal surface prior to coating the metal surface with the primer composition.  
     
     
         20 . The process of  claim 19 , wherein said roughening is conducted by acid etching or abrading said metal surface.  
     
     
         21 . The process of  claim 20 , wherein said metal surface is selected from the group consisting of aluminum, steel and titanium.