Ink composition

Abstract

An object of the present invention is to provide an ink compositions which, when used with an ink jet recording apparatus, can realize excellent ink ejection stability while maintaining safety and satisfactory penetration of ink. The ink composition according to the present invention comprises at least a colorant, a humectant, a glycol monoether as a penetrating agent, a 1,2-alkanediol, and water, the weight ratio of the glycol monoether to the 1,2-alkanediol being in the range of 1:5 to 5:1. According to another aspect of the present invention, there is provided an ink composition comprising at least a pigment, a dispersant for dispersing the pigment, a 1,2-alkanediol, and water as a main solvent, the content of the 1,2-alkanediol being 0.5 to 10% by weight based on the total amount of the ink composition.

1 . An ink composition comprising a colorant, a humectant, a glycol monoether, a 1,2-alkanediol, and water, 
 wherein the weight ratio of the glycol monoether to the 1,2-alkanediol is in the range of 1:5 to 5:1.    
     
     
         2 . The ink composition according to  claim 1 , wherein the weight ratio of the glycol monoether to the 1,2-alkanediol is in the range of 1:2 to 2:1.  
     
     
         3 . The ink composition according to  claim 1  or  2 , wherein the glycol monoether is glycol monobutyl ether.  
     
     
         4 . The ink composition according to any one of  claims 1  to  3 , wherein the 1,2-alkanediol has 6 to 8 carbon atoms.  
     
     
         5 . The ink composition according to any one of  claims 1  to  4 , wherein the glycol monoether is glycol monobutyl ether, the 1,2-alkanediol is 1,2-hexanediol, and the content of the 1,2-hexanediol is less than 2.5% by weight based on the total amount of the ink composition.  
     
     
         6 . The ink composition according to any one of  claims 1  to  5 , wherein the colorant is a water-soluble dye.  
     
     
         7 . The ink composition according to any one of  claims 1  to  5 , wherein the colorant is a pigment and which further comprises a dispersant for dispersing the pigment.  
     
     
         8 . The ink composition according to  claim 7 , wherein the dispersant is a block polymer resin having an acid value of 70 to 200.  
     
     
         9 . The ink composition according to any one of  claims 1  to  8 , which further comprises a nonionic surfactant.  
     
     
         10 . The ink composition according to  claim 9 , wherein the nonionic surfactant is an acetylene glycol surfactant.  
     
     
         11 . An ink jet recording method comprising the steps of: ejecting droplets of an ink composition; and depositing the droplets onto a recording medium to perform printing, wherein the ink composition is one according to any one of  claims 1  to  10 .  
     
     
         12 . A record produced by the recording method according to  claim 11 .  
     
     
         13 . An ink composition comprising a pigment, a dispersant for dispersing the pigment, a 1,2-alkanediol, and water as a main solvent, 
 wherein the content of the 1,2-alkanediol is 0.5 to 10% by weight based on the total amount of the ink composition.    
     
     
         14 . An ink composition comprising a pigment, a dispersant for dispersing the pigment, a 1,2-alkanediol, and water as a main solvent, 
 wherein the dispersant is a block polymer resin having an acid value of 70 to 200.    
     
     
         15 . The ink composition according to  claim 14 , which contains the 1,2-alkanediol in an amount of 0.5 to 10% by weight based on the ink composition.  
     
     
         16 . The ink composition according to any one of  claims 13  to  15 , wherein the 1,2-alkanediol is selected from the group consisting of 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, and a mixture thereof.  
     
     
         17 . The ink composition according to any one of  claims 13  to  16 , which contains, as the 1,2-alkanediol, 3 to 10% by weight of 1,2-butanediol.  
     
     
         18 . The ink composition according to any one of  claims 13  to  16 , which contains, as the 1,2-alkanediol, 3 to 10% by weight of 1,2-pentanediol.  
     
     
         19 . The ink composition according to any one of  claims 13  to  16 , which contains, as the 1,2-alkanediol, 1 to 6% by weight of 1,2-hexanediol.  
     
     
         20 . The ink composition according to any one of  claims 13  to  16 , which contains, as the 1,2-alkanediol, 0.5 to 3% by weight of 1,2-heptanediol.  
     
     
         21 . The ink composition according to any one of  claims 16  to  20 , wherein the block polymer resin as the dispersant has an acid value of 100 to 200.  
     
     
         22 . The ink composition according to any one of  claims 16  to  21 , wherein the dispersant is a block copolymer represented by AB, ABA, or ABC in which: 
 A is a hydrophilic block;  
 B is a hydrophobic block and contains at least 30% by weight, based on the weight of the B, of a non-acryl monomer selected from the group consisting of 
 (1)  
 CH 2 ═CH—R  
  wherein R represents a C 6 -C 20  substituted or unsubstituted alkyl, aryl, aralkyl, or alkaryl group,  
 (2)  
 CH 2 ═CH—OR 1    
  wherein R 1  represents a C 3 -C 20  substituted or unsubstituted alkyl, aryl, aralkyl, or alkaryl group,  
 (3)  
 CH 2 —CH—O—C(O)—R 1    
  wherein R 1 is as defined in (2), and  
 (4)  
 CH 2 ═CH—NR 2 R 3    
  wherein R 2  and R 3  are each independently selected from the group consisting of H and C 3 -C 20  substituted or unsubstituted alkyl, aryl, aralkyl, and alkaryl groups, provided that R 2  and R 3  do not simultaneously represent H; and  
 
 C may be any desired block.  
 
     
     
         23 . The ink composition according to any one of  claims 13  to  22 , which further comprises a nonionic surfactant.  
     
     
         24 . The ink composition according to  claim 23 , wherein the nonionic surfactant is an acetylene glycol surfactant.  
     
     
         25 . The ink composition according to  claim 23  or  24 , wherein the nonionic surfactant is contained in an amount of 0.1 to 5% by weight based on the total amount of the ink composition.  
     
     
         26 . The ink composition according to any one of  claims 13  to  25 , which further comprises a penetrating agent.  
     
     
         27 . The ink composition according to  claim 26 , wherein the penetrating agent is a glycol monoether.  
     
     
         28 . The ink composition according to any one of  claims 13  to  27 , which further comprises 2-pyrrolidone.  
     
     
         29 . The ink composition according to any one of  claims 13  to  28 , which is used in an ink jet recording method.  
     
     
         30 . The ink composition according to  claim 29 , wherein the ink jet recording method is a recording method using an ink jet head which forms ink droplets by the mechanical deformation of an electrostrictive device.  
     
     
         31 . An ink jet recording method comprising the steps of: ejecting droplets of an ink composition; and depositing the droplets onto a recording medium to perform printing, the ink composition being one according to any one of  claims 13  to  30 .  
     
     
         32 . A record produced by the recording method according to  claim 31.