Electroconductivity-controlling agent for cationic electrodeposition coating composition and method for adjusting electroconductivity of cationic electrodeposition coating composition therewith

Abstract

The present invention is intended to provide a technology preventing decrease in an electroconductivity or an throwing power of a cationic electrodeposition coating composition having a lower solid content and/or a lower ash content. Therefore, the present invention relates to: an electroconductivity-controlling agent used for a low solid content type cationic electrodeposition coating composition having 0.5 to 9.0 wt % of solid content of the coating composition, which agent includes an amino group-containing compound having 500 to 20000 of molecular weight and 200 to 500 mmol/100 g of amine value, to adjust an electroconductivity of the composition to 900 to 2000 μS/cm; a method for adjusting an electroconductivity of a cationic electrodeposition coating composition, which includes steps of: adding an electroconductivity-controlling agent to a low solid content type cationic electrodeposition coating composition having 0.5 to 9.0 wt % of solid content of the coating composition, and adjusting an electroconductivity of the cationic electrodeposition coating composition to 900 to 2000 μS/cm during the above step, wherein the electroconductivity-controlling agent includes an amino group-containing compound having 200 to 500 mmol/100 g of amine value; and the like.

1 . An electroconductivity-controlling agent used for a low solid content type cationic electrodeposition coating composition having 0.5 to 9.0 wt % of solid content of the coating composition, which agent includes an amino group-containing compound having 500 to 20000 of molecular weight and 200 to 500 mmol/100 g of amine value, to adjust an electroconductivity of the composition to 900 to 2000 μS/cm. 
   
   
       2 . The electroconductivity-controlling agent according to  claim 1 , wherein the amino group-containing compound is an amine modified epoxy resin or an amine modified acryl resin. 
   
   
       3 . The electroconductivity-controlling agent according to  claim 2 , wherein the amine modified epoxy resin is an epoxy resin wherein an epoxy group has been modified with an amine compound. 
   
   
       4 . The electroconductivity-controlling agent according to  claim 2 , wherein the amine modified acryl resin is an acryl resin having an epoxy group modified with an amine compound. 
   
   
       5 . The electroconductivity-controlling agent according to  claim 3 , wherein the epoxy resin is bisphenol type, t-butylcatechol type, phenol novolak type or cresol novolak type. 
   
   
       6 . A low solid content type cationic electrodeposition coating composition having 0.5 to 9.0 wt % of solid content of the coating composition, which includes an electroconductivity-controlling agent comprising an amino group-containing compound having 200 to 500 mmol/100 g of amine value, and which composition has 900 to 2000 μS/cm of electroconductivity. 
   
   
       7 . A method for adjusting an electroconductivity of a cationic electrodeposition coating composition, which includes steps of:
 adding an electroconductivity-controlling agent to a low solid content type cationic electrodeposition coating composition having 0.5 to 9.0 wt % of solid content of the coating composition, and   adjusting an electroconductivity of the cationic electrodeposition coating composition to 900 to 2000 μS/cm during the above step,   
     wherein the electroconductivity-controlling agent includes an amino group-containing compound having 200 to 500 mmol/100 g of amine value. 
   
   
       8 . A method for supplying an electroconductivity-controlling agent to a cationic electrodeposition coating composition, which includes steps of:
 supplying an electroconductivity-controlling agent to a low solid content type cationic electrodeposition coating composition having 0.5 to 9.0 wt % of solid content of the coating composition, and   adjusting an electroconductivity of the cationic electrodeposition coating composition to 900 to 2000 μS/cm during the above step,   
     wherein the electroconductivity-controlling agent includes an amino group-containing compound having 200 to 500 mmol/100 g of amine value.