Ink, ink jet recording method, recording unit, ink cartridge, and ink jet recording apparatus

Abstract

An ink jet ink contains at least a coloring material and a specific water-soluble organic solvent and has both excellent color developability and excellent humidity resistance. The coloring material exhibits a small (9 or less) color difference ΔE value which is determined by a method including a series of specific steps and is represented as the square root of (L 1 -L 2 ) 2 +(a 1 -a 2 ) 2 +(b 1 -b 2 ) 2 . The specific water-soluble organic solvent has an evaporation rate X smaller than that of water and a moisture absorptivity Y, the values of X and Y satisfying the relation of Y≦2.8X+10. The content of the specific water-soluble organic solvent is 50 mass % or more of the total amount of water-soluble organic solvents contained in the ink.

1 . An ink jet ink, comprising at least a coloring material and water-soluble organic solvent, characterized in that the ink jet ink satisfies the following conditions (A) and (B): 
 (A) A color difference ΔE judged by means of a method of judging properties of a coloring material including the following steps (1) to (3) is 9 or less,    (1) A step involving: applying a model ink comprising the coloring material, water, and a water-soluble organic solvent having an evaporation rate X (mass %) smaller than the evaporation rate of water and a moisture absorptivity Y (mass %) which is 20 or more and satisfies a relationship of Y≧2.8X+10; and applying a clear ink prepared by replacing only the coloring material of the model ink with water on the model ink in such a manner that an amount of the model ink is smaller than that of the clear ink,    (2) A step involving: leaving a recorded article obtained in the step (1) in an environment having a temperature of 25° C. and a humidity of 60% for 48 hours; and subsequently leaving the recorded article in an environment having a temperature of 30° C. and a humidity of 80% for 168 hours,    (3) A step of judging the color difference (ΔE) represented by the following expression (1) between the recorded article before the leaving for 168 hours and the recorded article after the leaving for 168 hours,      Δ E =√{square root over (( L   1 - L   2 ) 2 +( a   1 - a   2 ) 2 +( b   1 - b   2 ) 2 )}  (1)    (In the expression (1), L 1 , a 1 , and b 1  represent L, a, and b of an Lab colorimetric system after the leaving for 48 hours and before the leaving for 168 hours, respectively, and L 2 , a 2 , and b 2  represent L, a, and b of the Lab calorimetric system after the leaving for 168 hours, respectively.)    (B) A content of a water-soluble organic solvent in which the evaporation rate X (mass %) and the moisture absorptivity Y (mass %) satisfy a relationship represented by the following expression (2) in all the water-soluble organic solvents in the ink is 50 mass % or more.        Y≦ 2.8 X+ 10  (2)    (In the expression (2), X represents an evaporation rate and Y represents a moisture absorptivity.)    
   
   
       2 . An ink jet ink according to  claim 1 , wherein the number of the coloring material is at least two; and each of the coloring materials satisfies the conditions (A) and (B).  
   
   
       3 . An ink jet ink according to  claim 1 , wherein the content of the water-soluble organic solvent satisfying the expression (2) is 65 mass % or more with respect to a content of all the water-soluble organic solvents in the ink.  
   
   
       4 . An ink jet ink according to  claim 1 , wherein the coloring material comprises a compound represented by the following general formula (I) or a salt thereof;  
     
       
         
         
             
             
         
       
     
     wherein M's each independently represent a hydrogen atom, an alkali metal, an alkali earth metal, a cation of organic amine or an ammonium ion, and n's each independently represent 1 or 2.  
   
   
       5 . An ink jet ink according to  claim 1 , wherein the water-soluble organic solvent satisfying the expression (2) is selected from the group consisting of ethylene glycol, diethylene glycol, 2-pyrrolidone, 1,5-pentanediol, 1,6-hexanediol, and ethylene urea.  
   
   
       6 . An ink jet ink according to  claim 5 , wherein the water-soluble organic solvent satisfying the expression (2) comprises diethylene glycol, 2-pyrrolidone, or ethylene urea.  
   
   
       7 . An ink jet ink, comprising at least a coloring material and water-soluble organic solvent, characterized in that the ink jet ink satisfies the following conditions (A) and (B): 
 (A) The ink jet ink contains a compound represented by the following general formula (I) or a salt thereof,    (B) A content of a water-soluble organic solvent in which an evaporation rate X (mass %) and a moisture absorptivity Y (mass %) satisfy a relationship represented by the following expression (2) in all the water-soluble organic solvents in the ink is 50 mass % or more,                          wherein M's each independently represent a hydrogen atom, an alkali metal, an alkali earth metal, a cation of organic amine or an ammonium ion, and n's each independently represent 1 or 2.        Y≦ 2.8 X+ 10  (2)    (In the expression (2), X represents an evaporation rate and Y represents a moisture absorptivity.)    
   
   
       8 . An ink jet ink according to  claim 7 , further comprising C.I. Direct Yellow 132 as the coloring material.  
   
   
       9 . An ink jet ink according to  claim 7 , wherein the content of the water-soluble organic solvent satisfying the expression (2) is 65 mass % or more with respect to a content of all the water-soluble organic solvents in the ink.  
   
   
       10 . An ink jet ink according to  claim 7 , wherein the water-soluble organic solvent satisfying the expression (2) is selected from the group consisting of ethylene glycol, diethylene glycol, 2-pyrrolidone, 1,5-pentanediol, 1,6-hexanediol, and ethylene urea.  
   
   
       11 . An ink jet ink according to  claim 10 , wherein the water-soluble organic solvent satisfying the expression (2) comprises diethylene glycol, 2-pyrrolidone, or ethylene urea.  
   
   
       12 . An ink jet ink, comprising at least a coloring material and a water-soluble organic solvent, characterized in that: 
 the coloring material comprises a compound represented by the following general formula (I) or a salt thereof; and    the water-soluble organic solvent is selected from the group consisting of ethylene glycol, diethylene glycol, 2-pyrrolidone, 1,5-pentanediol, 1,6-hexanediol, and ethylene urea:                          wherein M's each independently represent a hydrogen atom, an alkali metal, an alkali earth metal, a cation of organic amine or an ammonium ion, and n's each independently represent 1 or 2.    
   
   
       13 . An ink jet ink according to  claim 12 , further comprising C.I. Direct Yellow 132 as the coloring material.  
   
   
       14 . An ink jet ink according to  claim 12 , wherein a content of the water-soluble organic solvent is 65 mass % or more with respect to a content of all water-soluble organic solvents in the ink.  
   
   
       15 . An ink jet ink according to  claim 12 , wherein the water-soluble organic solvent comprises diethylene glycol, 2-pyrrolidone, or ethylene urea.  
   
   
       16 . An ink jet recording method, comprising ejecting an ink by ink jet method, characterized in that the ink comprises the ink jet ink according to  claim 1 .  
   
   
       17 . An ink jet recording method, comprising ejecting an ink by ink jet method, characterized in that the ink comprises the ink jet ink according to  claim 7 .  
   
   
       18 . An ink jet recording method, comprising ejecting an ink by ink jet method, characterized in that the ink comprises the ink jet ink according to  claim 12 .  
   
   
       19 . An ink cartridge, comprising an ink storage portion for storing ink, characterized in that the ink comprises the ink jet ink according to  claim 1 .  
   
   
       20 . An ink cartridge, comprising an ink storage portion for storing ink, characterized in that the ink comprises the ink jet ink according to  claim 7 .  
   
   
       21 . An ink cartridge, comprising an ink storage portion for storing ink, characterized in that the ink comprises the ink jet ink according to  claim 12 .  
   
   
       22 . A recording unit, comprising an ink storage portion for storing ink and a recording head for ejecting the ink, characterized in that the ink comprises the ink jet ink according to  claim 1 .  
   
   
       23 . A recording unit, comprising an ink storage portion for storing ink and a recording head for ejecting the ink, characterized in that the ink comprises the ink jet ink according to  claim 7 .  
   
   
       24 . A recording unit, comprising an ink storage portion for storing ink and a recording head for ejecting the ink, characterized in that the ink comprises the ink jet ink according to  claim 12 .  
   
   
       25 . An ink jet recording apparatus, comprising an ink storage portion for storing ink and a recording head for ejecting the ink, characterized in that the ink comprises the ink jet ink according to  claim 1 .  
   
   
       26 . An ink jet recording apparatus, comprising an ink storage portion for storing ink and a recording head for ejecting the ink, characterized in that the ink comprises the ink jet ink according to  claim 7 .  
   
   
       27 . An ink jet recording apparatus, comprising an ink storage portion for storing ink and a recording head for ejecting the ink, characterized in that the ink comprises the ink jet ink according to  claim 12.