Method for coating vehicle bodies and parts thereof with rust-preventive ionomeric coatings

Abstract

The present invention is directed to a method for coating car or truck bodies, or part thereof, with a rust-preventive ionomer coating composition as the car or truck body is being conveyed along the assembly line as at the vehicle assembly plant. The method of the present invention is used as a replacement for the electrodeposition priming process used today at vehicle assembly plants.

1 . A coating method for applying a rust-preventive primer coating to an automotive substrate comprising: 
 (a) applying to at least one surface of an automotive substrate, a coating liquid comprising an aqueous dispersion of an ionomer resin;    (b) flash drying or baking said coating liquid on the substrate to form a rust-preventive primer layer; and,    (c) optionally, applying over said rust-preventive primer layer, a primer surfacer and/or an automotive topcoat finish such as a basecoat/clearcoat finish.    
   
   
       2 . The method according to  claim 1  wherein the substrate is a car or truck body or part thereof.  
   
   
       3 . The method of  claim 1  wherein the automotive substrate is in continuous movement throughout the primer paint application process steps (a) and (b) as it travels along an automotive assembly line.  
   
   
       4 . The method according to  claim 1  wherein the coating liquid is an aqueous dispersion of an ionomer resin partially or fully neutralized with a cation or mixture of cations.  
   
   
       5 . The method according to  claim 4  wherein the ionomer resin is fully neutralized or partially neutralized with a mixture of divalent metal ions and ammonium ions.  
   
   
       6 . The method according to  claim 5  wherein the ionomer resin is an ethylene-unsaturated carboxylic acid copolymer having an acid content of 10-35 wt %.  
   
   
       7 . The method according to  claim 5  wherein the ionomer resin is an ethylene-acrylic or methacrylic acid copolymer having an acid content of 10-35 wt %.  
   
   
       8 . The method according to  claim 6  wherein the divalent metal ion is selected from Zn.  
   
   
       9 . The method according to  claim 8  wherein the dispersion has a solids content of 10 to 45 wt %.  
   
   
       10 . The method according to  claim 5  wherein the dispersion further contains a non-water-soluble vapor phase corrosion inhibitor.  
   
   
       11 . A rust-preventive treated automotive substrate coated by the method of  claim 1 .  
   
   
       12 . A rust-preventive treated car or truck body substrate coated by the method of  claim 1 .  
   
   
       13 . An apparatus for applying a rust-preventive liquid ionomeric primer coating to an car or truck body, comprising an electrocoating tank at a vehicle assembly plant wherein the cathode or anode has been disabled.