Cationic electrodeposition coating composition and coated article therewith

Abstract

The present invention relates to a cationic electrodeposition coating composition comprising silica particles having pore volume of 0.44 to 1.8 ml/g and average particle size of no more than 10 μm, the composition showing square root of diffusion coefficient (√Tc) of no less than 2.5 upon diffusing a solution onto a coating film therewith; a cationic electrodeposition coating composition comprising silica particles having pore volume of 0.44 to 1.8 ml/g and average particle size of no more than 10 μm, wherein the composition shows minimum deposition pH of 11.90 to 12.00 during electrodeposition coating, and film resistance of 1,000 to 1,500 kΩ·cm 2 at film thickness of 15 μm and applied voltage of 240 V; and an article coated with such cationic electrodeposition coating composition. Therefore, the present invention can also provide a coating film formed with the cationic electrodeposition coating composition which can ensure higher corrosion resistance and higher throwing power in addition to other excellent coating properties, even if the resulting coating has extremely thin film thickness (e.g., about 7 μm).

1 . A cationic electrodeposition coating composition comprising silica particles having pore volume of 0.44 to 1.8 ml/g and average particle size of no more than 10 μm, the composition showing square root of diffusion coefficient (√Tc) of no less than 2.5 upon diffusing a solution onto a coating film therewith.  
   
   
       2 . The cationic electrodeposition coating composition according to  claim 1 , which further comprises an amine modified epoxy resin (A) and a blocked isocyanate curing agent (B), wherein weight ratio of the amine modified epoxy resin (A) to the blocked isocyanate curing agent (B) is 50/50 to 90/10 (A/B), and the blocked isocyanate curing agent (B) comprises a blocked aliphatic polyisocyanate and a blocked aromatic polyisocyanate, wherein weight ratio of the blocked aliphatic polyisocyanate to the blocked aromatic polyisocyanate is 3/1 to 1/3 (the blocked aliphatic polyisocyanate/the blocked aromatic polyisocyanate).  
   
   
       3 . The cationic electrodeposition coating composition according to  claim 1 , wherein content of the silica particles is 1 to 30% by weight relative to total weight of pigments.  
   
   
       4 . An article coated with the cationic electrodeposition coating composition according to  claim 1 .  
   
   
       5 . A cationic electrodeposition coating composition comprising silica particles having pore volume of 0.44 to 1.8 ml/g and average particle size of no more than 10 μm, wherein the composition shows minimum deposition pH of 11.90 to 12.00 during electrodeposition coating, and film resistance of 1,000 to 1,500 kΩ·cm 2  at film thickness of 15 μm and applied voltage of 240 V.  
   
   
       6 . The cationic electrodeposition coating composition according to  claim 5 , which further comprises an amine modified epoxy resin (A) and a blocked isocyanate curing agent (B), wherein weight ratio of the amine modified epoxy resin (A) to the blocked isocyanate curing agent (B) is 50/50 to 90/10 (A/B), and the blocked isocyanate curing agent (B) comprises a blocked aliphatic polyisocyanate and a blocked aromatic polyisocyanate, wherein weight ratio of the blocked aliphatic polyisocyanate to the blocked aromatic polyisocyanate is 3/1 to 1/3 (the blocked aliphatic polyisocyanate/the blocked aromatic polyisocyanate).  
   
   
       7 . The cationic electrodeposition coating composition according to  claim 5 , wherein content of the silica particles is 1 to 30% by weight relative to total weight of pigments.  
   
   
       8 . An article coated with the cationic electrodeposition coating composition according to  claim 5 .  
   
   
       9 . An article coated with the cationic electrodeposition coating composition according to  claim 2 .  
   
   
       10 . An article coated with the cationic electrodeposition coating composition according to  claim 3 .  
   
   
       11 . An article coated with the cationic electrodeposition coating composition according to  claim 6 .  
   
   
       12 . An article coated with the cationic electrodeposition coating composition according to  claim 7.