Coating composition containing polyamide-imide resin

Abstract

A coating composition comprises: (a) a resin solution containing a polyamide-imide resin and a solvent having a urea bond; and (b) a powdered solid lubricant. In general, the coating composition containing a polyamide-imide resin does not raise any concern about reproductive toxicity and has excellent lubrication durability.

1 . A coating composition comprising:
 (a) a resin solution containing a polyamide-imide resin and a solvent having a urea bond; and   (b) a powdered solid lubricant.   
     
     
         2 . The coating composition according to  claim 1 , wherein the solvent having a urea bond has a structure represented by the following chemical formula (A): 
       
         
           
           
               
               
           
         
       
       where R 1  represents a saturated hydrocarbon group having from 1 to 9 carbons and “n” represents an integer from 1 to 10. 
     
     
         3 . The coating composition according to  claim 2 , wherein R 1  is a saturated hydrocarbon group having from 1 to 3 carbons and “n” is an integer from 2 to 5 in the solvent having the structure represented by chemical formula (A). 
     
     
         4 . The coating composition according to  claim 1 , wherein the content of the polyamide-imide resin in the resin solution is from 10 to 60% by mass. 
     
     
         5 . The coating composition according to  claim 4 , wherein the content of the polyamide-imide resin in the resin solution is from 10 to 50% by mass. 
     
     
         6 . The coating composition according to  claim 1 , wherein the polyamide-imide resin is formed by polymerizing a diisocyanate compound and a trivalent carboxylic acid derivative having an acid anhydride group in the solvent having a urea bond. 
     
     
         7 . The coating composition according to  claim 6 , wherein the polyamide-imide resin is formed by reacting the diisocyanate compound, the trivalent carboxylic acid derivative having an acid anhydride group, and a dicarboxylic acid compound or diol compound and a tetracarboxylic acid derivative having two acid anhydride groups simultaneously. 
     
     
         8 . The coating composition according to  claim 6 , wherein the polyamide-imide resin is formed by first reacting a dicarboxylic acid compound or diol compound and an excessive amount of the diisocyanate compound to synthesize an oligomer having isocyanate groups at the ends and then adding and reacting the trivalent carboxylic acid derivative having an acid anhydride group and, optionally a tetracarboxylic acid derivative having two acid anhydride groups. 
     
     
         9 . The coating composition according to  claim 6 , wherein the polyamide-imide resin is formed by reacting the diisocyanate compound and an excessive amount of the trivalent carboxylic acid derivative having an acid anhydride group and, optionally a tetracarboxylic acid derivative having two acid anhydride groups to synthesize an oligomer having acids or acid anhydride end groups and then adding and reacting a dicarboxylic compound or diol compound. 
     
     
         10 . The coating composition according to  claim 1 , wherein the solid lubricant is selected from the group consisting of fluorine resins, molybdenum disulfide, and graphite. 
     
     
         11 . The coating composition according to  claim 1 , wherein an average primary particle diameter of the solid lubricant is from 0.1 to 20 μm. 
     
     
         12 . The coating composition according to  claim 11 , wherein the average primary particle diameter of the solid lubricant is from 0.1 to 10 μm. 
     
     
         13 . The coating composition according to  claim 1 , wherein the content of the solid lubricant in the total solid is from 5 to 90% by mass. 
     
     
         14 . The coating composition according to  claim 13 , wherein the content of the solid lubricant in the total solid is from 10 to 70% by mass. 
     
     
         15 . A lubricant comprising the coating composition according to  claim 1 . 
     
     
         16 . A device comprising a surface treatment, wherein the surface treatment comprises the lubricant according to  claim 15 . 
     
     
         17 . The device according to  claim 16 , selected from the group consisting of crank shafts, slide bearings, pistons, gaskets, gears, door panels, instrument panels, door looks, timing belts, body seals, glass runs, and weather stripping for sunroofs.