Microcapsules and processes for producing the same

Abstract

A microcapsule is produced by dispersing a liquid organic dispersion in an aqueous medium to form a capsule particle in the aqueous medium, the liquid organic dispersion containing an acid group-containing resin, a colored particle and an organic solvent, and the capsule particle comprising a disperse system containing the liquid organic dispersion, and a wall encapsulating the disperse system, wherein the acid group of the resin has been at least partly neutralized with an alkanolamine. The wall comprises the resin, and the resin may be crosslinked or cured with a crosslinking agent. Moreover, the process may comprise crosslinking or curing the resin constituting the wall with the crosslinking agent, and further crosslinking or curing the residual crosslinking agent with a polyfunctional compound. Such a process can produce a microcapsule has a small and uniform particle size while encapsulating a disperse system dispersed a colored particle in an oil phase.

1 . A microcapsule comprising a disperse system containing a colored particle dispersed in an oil phase, and a wall encapsulating the disperse system, wherein the wall comprises an acid group-containing resin, and the acid group of the resin has been at least partly neutralized with an alkanolamine represented by the following formula (1):  
     
       
         
         
             
             
         
       
       wherein R 1  and R 2  are the same or different and each represents a hydrogen atom or a hydrocarbon group which may have a hydroxyl group as a substituent; R 1  and R 2  may bond to each other to form a nitrogen-containing ring together with the adjacent nitrogen atom; and R 3  represents a linear or branched alkylene group.  
     
   
   
       2 . A microcapsule according to  claim 1 , wherein the disperse system comprises an electrically insulating dielectric liquid, and a single or a plurality of species of colored particle(s) dispersed in the dielectric liquid.  
   
   
       3 . A microcapsule according to  claim 1 , wherein the colored particle is charged in the oil phase and movable electrophoretically in the microcapsule by a potential difference.  
   
   
       4 . A microcapsule according to  claim 1 , wherein the colored particle has a mean particle size of 10 to 100 nm, and the microcapsule has a mean particle size of 1 to 1000 μm.  
   
   
       5 . A microcapsule according to  claim 1 , which is interposed between a pair of electrodes, for displaying an image by electrophoresis of the colored particle.  
   
   
       6 . The microcapsule according to  claim 1 , wherein the alkanolamine of formula (1) is 3-dimethylamino-2,2-dimethyl-1-propanol.