Pigment dispersion and actinic radiation curable type ink jet ink composition

Abstract

A pigment dispersion including photopolymerizable compounds and pigments as well as an actinic radiation curable type ink jet composition including photopolymerizable compounds, photopolymerization initiators, and pigments are provided. The hydrophilicity δm of the surface of pigments incorporated therein is at most 22.

1 . A pigment dispersion comprising photopolymerizable compounds and pigments, wherein: 
 hydrophilicity δm of the surface of pigments incorporated therein is at most 22,    which hydrophilicity δm is specifically determined based on the following steps,    pigments are floated on a definite amount of water (B ml), and while stirring, acetone is dripped through a burette of which tip is placed in the water so that acetone is not directly poured onto the pigment,    using amount of acetone (A ml) dripped to sink the pigment, δm is calculated based on the formula below.     δ m =( A·δ   acetone   +B·δ   acetone )/( A+B ) δ acetone =9.75(cal 1/2 ·cm −1/2 ) δ water =23.43(cal 1/2 ·cm −1/2 )   
     
     
         2 . A pigment dispersion of  claim 1 , wherein: 
 said photopolymerizable compounds are photopolymerizable compounds containing an oxetane ring.    
     
     
         3 . A pigment dispersion of  claim 2 , wherein: 
 said photopolymerizable compounds are photopolymerizable compounds having 1-4 oxetane rings.    
     
     
         4 . A pigment dispersion of  claim 1 , wherein: 
 said photopolymerizable compounds are epoxy compounds.    
     
     
         5 . A pigment dispersion of  claim 4 , wherein: 
 said epoxy compounds are selected from aromatic epoxides and alictclic epoxides.    
     
     
         6 . A pigment dispersion of  claim 1 , wherein: 
 said photopolymerizable compounds are vinyl ether compounds.    
     
     
         7 . A pigment dispersion of  claim 6 , wherein: 
 said vinyl ether compounds are selected from divinyl ether compounds and trivinyl compounds.    
     
     
         8 . A pigment dispersion of  claim 1  to  7 , wherein: 
 said hydrophilicity δm of the surface of pigments incorporated therein is at most 21.5.    
     
     
         9 . An actinic radiation curable type ink jet composition comprising photopolymerizable compounds, photopolymerization initiators, and pigments wherein: 
 hydrophilicity δm of the surface of pigments incorporated therein is at most 22,    which hydrophilicity δm is specifically determined based on the following steps,    pigments are floated on a definite amount of water(B ml), and while stirring, acetone is dripped through a burette of which tip is placed in the water so that acetone is not directly poured onto the pigment,    using amount of acetone (A ml) dripped to sink the pigment, δm is calculated based on the formula below.     δ m =( A·δ   acetone   +B·δ   acetone )/( A+B ) δ acetone =9.75(cal 1/2 ·cm −1/2 ) δ water =23.43(cal 1/2 ·cm −1/2 )   
     
     
         10 . An actinic radiation curable type ink jet composition of  claim 9 , wherein: 
 said photopolymerizable compounds are photopolymerizable compounds containing an oxetane ring.    
     
     
         11 . An actinic radiation curable type ink jet composition of  claim 10 , wherein: 
 said photopolymerizable compounds are photopolymerizable compounds having 1-4 oxetane rings.    
     
     
         12 . An actinic radiation curable type ink jet composition of  claim 9 , wherein: 
 said photopolymerizable compounds are epoxy compounds.    
     
     
         13 . An actinic radiation curable type ink jet composition of  claim 12 , wherein: 
 said epoxy compounds are selected from aromatic epoxides and alictclic epoxides.    
     
     
         14 . An actinic radiation curable type ink jet composition of  claim 9 , wherein: 
 said photopolymerizable compounds are vinyl ether compounds.    
     
     
         15 . An actinic radiation curable type ink jet composition of  claim 14 , wherein: 
 said vinyl ether compounds are selected from divinyl ether compounds and trivinyl compounds.    
     
     
         16 . An actinic radiation curable type ink jet composition of  claim 9 , wherein: 
 said photopolymerization initiators are aromatic onium salts.    
     
     
         17 . An actinic radiation curable type ink jet composition of  claim 9 , wherein: 
 said photopolymerization initiators are sulfonium salts which generate no benzene by exposure to actinic radiation.    
     
     
         18 . An actinic radiation curable type ink jet composition of  claim 17 , wherein: 
 said sulfonium salts are sulfonium salt compounds represented by following General Formulas (1)-(4).                           (In above General Formulas (1)-(4), R 1 -R 17  each represent a hydrogen atom or a substituent. None of R 1 -R 3  simultaneously represent a hydrogen atom, none of R 4 -R 7  simultaneously represent a hydrogen atom, and none of R 12 -R 17  simultaneously represent a hydrogen atom. X represents a non-nucleophilic anionic residual group.)    
     
     
         19 . An actinic radiation curable type ink jet composition of  claim 9  to  18 , wherein: 
 said hydrophilicity am of the surface of pigments incorporated therein is at most 21.5.