Cationic electrodeposition coating and application thereof

Abstract

The present invention relates to a cationic electrodeposition coating composition, which provides an uncured electrodeposited film having storage elasticity modulus (G′) at 140° C. within a range of from 80 to 500 dyn/cm 2 and loss elasticity modulus (G″) at 80° C. within a range of from 10 to 150 dyn/cm 2 , and which is superior in smoothness and edge coatability; and a method for establishing both of smoothness and edge coatability therewith; as well as; a cationic electrodeposition coating composition comprising crosslinked resin particles having an average particle size within a range of from 1.0 to 3.0 μm and thermal softening temperature within a range of from 120 to 180° C.; and a method for producing a cationic electrodeposition film having established smoothness and edge coatability, wherein the cationic electrodeposition film is prepared by applying a voltage to an article immersed in a cationic electrodeposition coating composition, and wherein the cationic electrodeposition coating composition comprises crosslinked resin particles having an average particle size within a range of from 1.0 to 3.0 μm and thermal softening temperature within a range of from 120 to 180° C. The present invention can provide a method for establishing both of surface smoothness and edge coatability of the cationic electrodeposition coating composition, and cationic electrodeposition coating composition which can provide an electrodeposition film having excellent surface conditions.

1 . A cationic electrodeposition coating composition, which provides an uncured electrodeposited film having storage elasticity modulus (G′) at 140° C. within a range of from 80 to 500 dyn/cm 2  and loss elasticity modulus (G″) at 80° C. within a range of from 10 to 150 dyn/cm 2 , and which is superior in smoothness and edge coatability. 
     
     
         2 . The cationic electrodeposition coating composition according to  claim 1 , which comprises a cationic epoxy resin, a blocked isocyanate curing agent, and if necessary, a crosslinked resin particle and/or an inorganic pigment. 
     
     
         3 . A method for producing a cationic electrodeposition film having established smoothness and edge coatability, wherein the cationic electrodeposition film is prepared by applying a voltage to an article immersed in a cationic electrodeposition coating composition, which includes steps of:
 adjusting storage elasticity modulus of an uncured electrodeposited film of the cationic electrodeposition coating composition (G′) at 140° C. within a range of from 80 to 500 dyn/cm 2 , and   adjusting loss elasticity modulus of an uncured electrodeposited film of the cationic electrodeposition coating composition (G″) at 80° C. within a range of from 10 to 150 dyn/cm 2 .   
     
     
         4 . The method according to  claim 3 , wherein crosslinked resin particles having an average particle size within a range of from 1.0 to 3.0 μm are added to the cationic electrodeposition coating composition in order to adjust storage elasticity modulus and loss elasticity modulus. 
     
     
         5 . The method according to  claim 4 , wherein content of the crosslinked resin particles is 3 to 15% by weight relative to weight of resin solid contents in the cationic electrodeposition coating composition. 
     
     
         6 . The method according to  claim 3 , wherein an inorganic pigment is added to the cationic electrodeposition coating composition, wherein content of the inorganic pigment is 10 to 20% by weight relative to weight of solid contents in the cationic electrodeposition coating composition, in order to adjust storage elasticity modulus and loss elasticity modulus. 
     
     
         7 . The method according to  claim 3 , wherein crosslinked resin particles having an average particle size within a range of from 1.0 to 3.0 μm and an inorganic pigment are added to the cationic electrodeposition coating composition, wherein content of the inorganic pigment is 0.5 to 10% by weight relative to weight of solid contents in the cationic electrodeposition coating composition, in order to adjust storage elasticity modulus and loss elasticity modulus. 
     
     
         8 . The method according to  claim 7 , wherein content of the crosslinked resin particles is 3 to 15% by weight relative to weight of resin solid contents in the cationic electrodeposition coating composition.