Organic pigment fine-particle, and method of producing the same

Abstract

A method of producing a dispersion of a pigment, comprising: bringing a solution in which an organic pigment is dissolved, and an aqueous medium, into contact with each other in a channel having an equivalent diameter of 1 mm or less, thereby making the pigment into a fine particle thereof, wherein at least one of the solution and the aqueous medium comprises at least one anionic dispersing agent.

1 . A method of producing a dispersion of a pigment, comprising: 
 bringing a solution in which an organic pigment is dissolved, and an aqueous medium, into contact with each other in a channel having an equivalent diameter of 1 mm or less, thereby making the pigment into a fine particle thereof, wherein at least one of the solution and the aqueous medium comprises at least one anionic dispersing agent.    
     
     
         2 . The method according to  claim 1 , wherein a flow of the solution in which an organic pigment is dissolved is contacted with a flow of the aqueous medium, in the channel having an equivalent diameter of 1 mm or less, to form a flow of liquid comprising the pigment in the form of fine particles.  
     
     
         3 . The method according to  claim 1 , wherein the organic pigment solution is alkaline.  
     
     
         4 . The method according to  claim 1 , wherein at least one of the organic pigment solution and the aqueous medium comprises at least one polymer dispersing agent.  
     
     
         5 . The method according to  claim 4 , wherein the at least one polymer dispersing agent comprises polyvinyl pyrrolidone.  
     
     
         6 . The method according to  claim 1 , wherein the at least one anionic dispersing agent is contained in the aqueous medium, and a nonionic dispersing agent and/or a polymer dispersing agent is contained in the organic pigment solution.  
     
     
         7 . The method according to  claim 1 , further comprising changing a hydrogen ion exponent (pH) of the organic pigment solution while flowing.  
     
     
         8 . The method according to  claim 1 , wherein the organic pigment solution and the aqueous medium are introduced to the channel continuously.  
     
     
         9 . The method according to  claim 1 , further comprising controlling a reaction for forming the pigment fine particle by controlling a time during which the channel retains a liquid flow therein.