Inkjet ink

Abstract

This invention pertains to an ink for inkjet printing, in particular to an aqueous ink comprising a self-dispersing pigment colorant and certain soluble polymers which enhance print quality without compromising jetting performance.

1 . An aqueous inkjet ink composition comprising: 
 (a) an SDP colorant;    (b) an aqueous vehicle; and    (c) a soluble structured polymer.    
     
     
         2 . The ink of  claim 1 , wherein the soluble structured polymer is present at a P/B ratio of between about 0.5 to about 20.  
     
     
         3 . The ink of  claim 1 , wherein the soluble polymer is a substantially linear, anionic polymer having a number average molecular weight in the range of about 1,000 to about 20,000.  
     
     
         4 . The ink of  claim 1 , wherein the substantially linear soluble polymer is a block copolymer.  
     
     
         5 . The ink of  claim 1 , further comprising a dispersed polymer binder.  
     
     
         6 . The ink of  claim 1 , wherein the dispersed polymer binder is a polyurethane.  
     
     
         7 . The ink of  claim 1 , wherein the self-dispersing pigment is a self-dispersing carbon black pigment comprising anionic hydrophilic moieties.  
     
     
         8 . The ink of  claim 7 , wherein the anionic hydrophillic moieties on the self-dispersing carbon black pigment are primarily carboxyl groups directly attached to the pigment surface.  
     
     
         9 . An inkjet ink set for color printing, comprising at least three differently colored inks, at least one of which is cyan, at least one of which is magenta and at least one of which is yellow, wherein at least one of the inks is an aqueous inkjet ink composition comprising: 
 (a) an SDP colorant;    (b) an aqueous vehicle; and    (c) a soluble structured polymer.    
     
     
         10 . The inkjet ink set of  claim 9 , wherein the soluble structured polymer is present at a P/B ratio of between about 0.5 to about 20.  
     
     
         11 . The inkjet ink set of  claim 9 , wherein the soluble polymer is a substantially linear, anionic polymer having a number average molecular weight in the range of about 1,000 to about 20,000.  
     
     
         12 . The inkjet ink set of  claim 9 , wherein the substantially linear soluble polymer is a block copolymer.  
     
     
         13 . The inkjet ink set of  claim 9 , further comprising a dispersed polymer binder.  
     
     
         14 . The inkjet ink set of  claim 9 , wherein the dispersed polymer binder is a polyurethane.  
     
     
         15 . An inkjet ink set for color printing, comprising at least four differently colored inks, at least one of which is cyan, at least one of which is magenta, at least one of which is yellow, and at least one of which is black, wherein at least one of the inks is a black ink comprising: 
 (a) an SDP colorant;    (b) an aqueous vehicle; and    (c) a soluble structured polymer,    wherein the SDP colorant is a self-dispersing carbon black pigment comprising anionic hydrophilic moieties.    
     
     
         16 . The inkjet ink set of  claim 15 , wherein the anionic hydrophillic moieties on the self-dispersing carbon black pigment are primarily carboxyl groups directly attached to the pigment surface.  
     
     
         17 . The inkjet ink set of  claim 15 , wherein the soluble structured polymer is present at a P/B ratio of between about 0.5 to about 20.  
     
     
         18 . The inkjet ink set of  claim 15 , wherein the soluble polymer is a substantially linear, anionic polymer having a number average molecular weight in the range of about 1,000 to about 20,000.  
     
     
         19 . The inkjet ink set of  claim 15 , wherein the substantially linear soluble polymer is a block copolymer.  
     
     
         20 . The inkjet ink set of  claim 15 , further comprising a dispersed polymer binder.  
     
     
         21 . The inkjet ink set of  claim 15 , wherein the dispersed polymer binder is a polyurethane.