Electrodepositable coating compositions and related methods

Abstract

An electrodepositable coating composition is provided including a resinous phase and corrosion resisting particles dispersed in an aqueous medium. Methods of preparing and using the composition also are provided.

1 . An electrodepositable coating composition comprising: 
 (a) a resinous phase comprising: 
 (i) an active hydrogen-containing, ionic salt group-containing resin; and  
 (ii) at least one curing agent; and  
   (b) particles having a calculated equivalent spherical diameter of no more than 200 nanometers and comprising a plurality of inorganic oxides wherein at least one inorganic oxide comprises zinc, cerium, yttrium, magnesium, lithium, aluminum, tin, or calcium.    
   
   
       2 . The electrodepositable coating composition of  claim 1 , wherein the particles (b) comprise corrosion resisting particles.  
   
   
       3 . The electrodepositable coating composition of  claim 1 , wherein the particles are selected from (i) particles comprising oxides of cerium, zinc, and silicon; (ii) particles comprising oxides of calcium, zinc and silicon; (iii) particles comprising oxides of phosphorous, zinc and silicon; (iv) particles comprising oxides of yttrium, zinc, and silicon; (v) particles comprising oxides of molybdenum, zinc, and silicon; (vi) particles comprising oxides of boron, zinc, and silicon; (vii) particles comprising oxides of cerium, aluminum, and silicon, (viii) particles comprising oxides of magnesium or tin and silica, and (ix) particles comprising oxides of cerium, boron, and silicon, or a mixture thereof.  
   
   
       4 . The electrodepositable coating composition of  claim 3 , wherein the particles comprise oxides of cerium, zinc, and silicon.  
   
   
       5 . The electrodepositable coating composition of  claim 1 , wherein the particles are selected from particles comprising: 
 (i) 10 to 25 percent by weight zinc oxide, 0.5 to 25 percent by weight cerium oxide, and 50 to 89.5 percent by weight silica;    (ii) 10 to 25 percent by weight zinc oxide, 0.5 to 25 percent by weight calcium oxide, and 50 to 89.5 percent by weight silica;    (iii) 10 to 25 percent by weight zinc oxide, 0.5 to 25 percent by weight yttrium oxide, and 50 to 89.5 percent by weight silica;    (iv) 10 to 25 percent by weight zinc oxide, 0.5 to 50 percent by weight phosphorous oxide, and 25 to 89.5 percent by weight silica;    (v) 10 to 25 percent by weight zinc oxide, 0.5 to 50 percent by weight boron oxide, and 25 to 89.5 percent by weight silica;    (vi) 10 to 25 percent by weight zinc oxide, 0.5 to 50 percent by weight molybdenum oxide, and 25 to 89.5 percent by weight silica;    (vii) 0.5 to 25 percent by weight cerium oxide, 0.5 to 50 percent by weight boron oxide, and 25 to 99 percent by weight silica;    (viii) 0.5 to 25 percent by weight cerium oxide, 0.5 to 50 percent by weight aluminum oxide, and 25 to 99 percent by weight silica;    (ix) 0.5 to 75 percent by weight magnesium or tin oxide, and 25 to 99.5 percent by weight silica;    (x) 0.5 to 25 percent by weight cerium oxide, 0.5 to 25 percent by weight zinc oxide, 0.5 to 25 percent by weight boron oxide, and 25 to 98.5 percent by weight silica;    (xi) 0.5 to 25 percent by weight yttrium oxide, 0.5 to 25 percent by weight phosphorous oxide, 0.5 to 25 percent by weight zinc oxide, and 25 to 98.5 percent by weight silica;    (xii) 0.5 to 5 percent by weight yttrium oxide, 0.5 to 5 percent by weight molybdenum oxide, 0.5 to 25 percent by weight zinc oxide, 0.5 to 5 percent by weight cerium oxide and 60 to 98 percent by weight silica; and    (xiii) mixtures thereof,    wherein the percent by weights are based on the total weight of the particles.    
   
   
       6 . The electrodepositable coating composition of  claim 1 , wherein the particles are prepared by a process comprising: 
 (a) introducing a reactant into a plasma chamber;    (b) heating the reactant by means of a plasma as the reactant flows through the plasma chamber, yielding a gaseous reaction product;    (c) contacting the gaseous reaction product with a plurality of quench streams injected into the reaction chamber through a plurality of quench gas injection ports, wherein the quench streams are injected at a flow rate and injection angle that results in the impingement of the quench streams with each other within the gaseous reaction product stream, thereby producing ultrafine solid particles; and    (d) passing the ultrafine solid particles through a converging member.    
   
   
       7 . The electrodepositable coating composition according to  claim 1 , wherein at least a portion of the particles are dispersed in one or both of the resin (i) and the curing agent (ii) prior to dispersing the resinous phase in the aqueous medium.  
   
   
       8 . The electrodepositable coating composition according to  claim 1 , further comprising catalyst particles selected from the group consisting of bismuth oxide; bismuth silicate; bismuth titanate; molybdenum oxide; molybdenum silicate; molybdenum titanate; tungsten oxide; tungsten silicate; tungsten titanate; and combinations thereof, wherein the catalyst nanoparticles have an average B.E.T. specific surface area greater than 20 square meters per gram (m 2 /g).  
   
   
       9 . The electrodepositable coating composition according to  claim 8 , wherein the catalyst particles comprise bismuth oxide.  
   
   
       10 . The electrodepositable coating composition according to  claim 1 , wherein the catalyst nanoparticles are present in the coating composition in an amount ranging from 0.1 to 5.0 percent by weight of metal based on weight of total resin solids present in the electrodepositable coating composition.  
   
   
       11 . The electrodepositable coating composition according to  claim 1 , wherein the resin (a) comprises active hydrogens derived from reactive hydroxyl groups and/or primary amine groups.  
   
   
       12 . The electrodepositable coating composition according to  claim 1 , wherein the resin (a) comprises the reaction product of a polyepoxide and a diglycidyl ether of a polyhydric phenol.  
   
   
       13 . The electrodepositable coating composition according to  claim 1 , wherein at least a portion of the active hydrogens present in the resin (a) comprise primary amine groups derived from the reaction of a ketimine-containing compound and an epoxy group-containing material.  
   
   
       14 . The electrodepositable coating composition according to  claim 1 , wherein the curing agent (b) is at least partially blocked with a blocking agent.  
   
   
       15 . The electrodepositable coating composition according to  claim 1 , which is free of lead-containing compounds.  
   
   
       16 . An electrodepositable coating composition comprising: 
 (a) a resinous phase comprising: 
 (i) an active hydrogen-containing, ionic salt group-containing resin; and  
 (ii) a curing agent;  
   (b) catalyst particles selected from the group consisting of bismuth oxide, bismuth silicate, bismuth titanate, molybdenum oxide, molybdenum silicate, molybdenum titanate, tungsten oxide, tungsten silicate, tungsten titanate, or a combination thereof, wherein the catalyst particles have an average B.E.T. specific surface area greater than 20 square meters per gram; and    (c) corrosion resisting particles having a calculated equivalent spherical diameter of no more than 200 nanometers and comprising a plurality of inorganic oxides comprising at least one inorganic oxide comprising zinc, cerium, yttrium, manganese, magnesium, molybdenum, lithium, aluminum, or calcium.    
   
   
       17 . A method for electrocoating a conductive substrate serving as a cathode in an electrical circuit comprising the cathode and an anode, the cathode and anode being immersed in an aqueous electrocoating composition, the method comprising passing electric current between the cathode and anode to cause deposition of the electrocoating composition onto the substrate as a substantially continuous film, the aqueous electrocoating composition comprising (1) a resinous phase comprising: (a) an active hydrogen group-containing, ionic group-containing electrodepositable resin; and (b) a curing agent, and (2) corrosion resisting particles having a calculated equivalent spherical diameter of no more than 200 nanometers and comprising a plurality of inorganic oxides wherein at least one inorganic oxide comprises zinc, cerium, yttrium, magnesium, lithium, aluminum, tin, or calcium.