Pseudoplastic powder lacquer slurry free of organic solvents, method for production and the use thereof

Abstract

A pseudoplastic powder clearcoat slurry which is free from organic solvents and comprises solid and/or highly viscous, particles which are dimensionally stable under storage and application conditions and have an average size of from 0.8 to 20 μm, at least 99% of the particles having a size ≦30 μm, which is preparable by 1) emulsifying an organic solution comprising binder and crosslinking agent to give an emulsion of the oil-in-water type, 2) removing the organic solvent or solvents, and 3) wet grinding the resulting slurry; and also the use of the powder clearcoat slurry to produce clearcoats for automotive OEM finishing and automotive refinish, for furniture coating and for industrial coating, including coil coating, container coating and the coating of electrical components.

1 . A method comprising 
 1) emulsifying an organic solution comprising at least one binder, at least one crosslinking agent, and at least one organic solvent to give an emulsion,    2) removing the at least one organic solvent to provide a slurry, and    3) wet grinding the slurry to form a pseudoplastic powder clearcoat slurry that is free from organic solvents and comprises solid and/or highly viscous particles that are dimensionally stable under storage and application conditions and have an average size of from 0.8 to 20 μm, at least 99% of the particles having a size≦30μm.    
     
     
         2 . The method of  claim 1  further comprising filtering the wet-ground slurry.  
     
     
         3 . The method of  claim 1  further comprising replacing the removed solvent at least partially with water.  
     
     
         4 . The method of  claim 1 , wherein the pseudoplastic powder clearcoat slurry has an ion-forming group content of from 0.05 to 1 meq/g and a neutralizing agent content of from 0.05 to 1 meq/g.  
     
     
         5 . The method of  claim 1 , wherein the pseudoplastic powder clearcoat slurry has a viscosity of (i) from 50 to 1,000 mPas at a shear rate of 1,000 s −1  and (ii) from 150 to 8000 mPas at a shear rate of 100 s −1 .  
     
     
         6 . The method of  claim 1 , wherein the pseudoplastic powder clearcoat slurry has a solids content of from 10 to 60% by weight.  
     
     
         7 . The method of  claim 1 , wherein the average size of the particles is from 2 to 6 μm.  
     
     
         8 . The method of  claim 1 , wherein the pseudoplastic powder clearcoat slurry further comprises ionic thickeners and nonionic associative thickeners.  
     
     
         9 . The method of  claim 1 , wherein the binder comprises a polyol and the crosslinking agent comprises a blocked polyisocyanate and/or a tris(alkoxycarbonylamino)triazine.  
     
     
         10 . The method of  claim 1 , wherein the binder comprises a polyacrylate and the crosslinking agent comprises a blocked polyisocyanate.  
     
     
         11 . The method of  claim 1 , wherein the particles have a minimum film-forming temperature of at least 0° C.  
     
     
         12 . The slurry of  claim 1 , wherein the particles have a minimum film-forming temperature of at least 10° C.  
     
     
         13 . The method of  claim 1 , wherein the removing of the organic solvents is conducted at a temperature below the minimum film-forming temperature of the particles.  
     
     
         14 . The method of  claim 1 , wherein the pseudoplastic powder clearcoat slurry is free from external emulsifiers.  
     
     
         15 . The method of  claim 1 , wherein the wet grinding is conducted at a temperature above the minimum film-forming temperature of the particles.  
     
     
         16 . The method of  claim 2 , wherein the method consists of the emulsifying, the removing, the wet grinding, the filtering, and, optionally, replacing the removed solvent at least partially with water.  
     
     
         17 . The method of  claim 1  further comprising applying the pseudoplastic powder clearcoat slurry to at least one surface of an article.