Magnetic actuated-milled pigment dispersions and process for making thereof

Abstract

The disclosure provides pigment dispersions having an average particle size of from about 10 nm to about 500 nm prepared by employing a magnetic actuated milling process and system. In embodiments, the pigment dispersions have an average particle size of less than 100 nm.

1 . A pigment dispersion comprising a milled pigment having an average particle size of from about 10 nm to about 500 nm dispersed in an aqueous medium, wherein the pigment dispersion is prepared from the method comprising:
 contacting a pigment with magnetic particles and non-magnetic abrasive particles;   agitating the pigment, and non-magnetic abrasive particles;   applying a constant magnetic field to the magnetic particles;   milling the pigment with the magnetic and the non-magnetic abrasive particles until the average particle size is within the desired range of from about 10 nm to about 500 nm.   
     
     
         2 . The pigment dispersion of  claim 1 , wherein the pigment dispersion has a viscosity of from about 0.1 cP to about 100,000 cP at 25° C. 
     
     
         3 . The pigment dispersion of  claim 1 , wherein the magnetic particles are selected from the group consisting of a paramagnetic material, ferromagnetic material, antiferromagnetic material and mixtures thereof. 
     
     
         4 . The pigment dispersion of  claim 1 , wherein the non-magnetic abrasive particles have a particle diameter size of less than 1 mm. 
     
     
         5 . The pigment dispersion of  claim 1 , wherein the non-magnetic abrasive particles are selected from the group consisting of aluminum oxide, SiC, cerium oxide, zirconium oxide, ferric oxide, bauxite, cubic zirconia powder, diamond powder, and mixtures thereof. 
     
     
         6 . The pigment dispersion of  claim 1 , wherein the non-magnetic abrasive particles have a nano indentation hardness value of at least 4.9 GPa. 
     
     
         7 . The pigment dispersion of  claim 1 , wherein the weight ratio of magnetic particles to non-magnetic abrasive particles is in a range of from about 0.5:10 to about 10:0.5. 
     
     
         8 . The pigment dispersion of  claim 1 , wherein the volume ratio of the magnetic particles and non-magnetic abrasive particles to the pigment is in a range of from about 0.5:10 to about 10:0.5. 
     
     
         9 . The pigment dispersion of  claim 1 , wherein the weight of the milled pigment is from about 1 to about 50% by weight of the pigment dispersion. 
     
     
         10 . The pigment dispersion of  claim 1 , wherein the pigment dispersion comprises water. 
     
     
         11 . The pigment dispersion of  claim 1 , wherein the magnetic field has a strength of from about 10 Gauss to about 50,000 Gauss. 
     
     
         12 . The pigment dispersion of  claim 1 , wherein the magnetic field is applied through one or more electromagnets. 
     
     
         13 . The pigment dispersion of  claim 1 , wherein the magnetic field is applied through a permanent magnet. 
     
     
         14 . A pigment dispersion comprising a milled yellow pigment having an average particle size of from about 10 nm to about 100 nm dispersed in an aqueous medium, wherein the pigment dispersion is prepared from the method comprising:
 contacting a yellow pigment with magnetic particles and non-magnetic abrasive particles;   applying a constant magnetic field to the magnetic particles;   milling the yellow pigment with the magnetic and the non-magnetic abrasive particles until the average particle size is less than 100 nm, wherein the milled yellow pigment has an average particle size of from about 50 nm to about 95 nm.   
     
     
         15 . The pigment dispersion of  claim 14 , wherein the pigment dispersion has a viscosity of from about 0.1 cP to about 100,000 cP. 
     
     
         16 . The pigment dispersion of  claim 14 , wherein the pigment comprises 2-((2-methoxy-4-nitrophenyl)azo)-n-(2-methoxyphenyl)-3-oxo-butanamid. 
     
     
         17 . (canceled) 
     
     
         18 . The pigment dispersion of  claim 14 , wherein the weight of the milled pigment is from about 1 to about 50% by weight of the pigment dispersion. 
     
     
         19 . The pigment dispersion of  claim 14 , wherein the constant magnetic field has a strength of from about 10 Gauss to about 50,000 Gauss. 
     
     
         20 . The pigment dispersion of  claim 14 , wherein the constant magnetic field is applied through a permanent magnet.