Ink composition and a method for ink jet recording

Abstract

A white ink composition for ink jet recording characterized in comprising at least a white pigment, a polymerizable compound, and a polymerization initiator and having a viscosity of 10 to 500 Pa·s at 30° C. A method for ink jet recording comprising the steps of: heating an ink in an ink-jet head to be not less than 40° C. and jetting the ink onto an ink-jet recording medium.

What is claimed is:  
     
         1 . An ink for ink jet recording comprising at least a pigment, a polymerizable compound, and a polymerization initiator, wherein the ink has a viscosity of 10 to 500 Pa·s at 30° C. and a viscosity of 7 to 30 mPa·s when heated to at least 40° C.  
     
     
         2 . The ink for ink jet recording of  claim 1 , wherein the ink is a white ink and the pigment comprises a white pigment.  
     
     
         3 . The ink for ink jet recording of  claim 2 , wherein the content ratio of the white pigment is from 1 to 50 percent by weight.  
     
     
         4 . The ink for ink jet recording of  claim 2 , wherein the pigment comprises a white inorganic pigment, a white organic pigment or fine hollow polymer particles.  
     
     
         5 . The ink for ink jet recording of  claim 4 , wherein the white inorganic pigment is a titanium oxide.  
     
     
         6 . The ink for ink jet recording of  claim 2 , wherein the average particle diameter of the pigment is from 0.1 to 1 μm.  
     
     
         7 . The ink for ink jet recording of  claim 2 , comprising solvent not more than 7 weight % based on the ink.  
     
     
         8 . The ink for ink jet recording of  claim 2 , comprising the surface tension of 27 to 50 mN/m.  
     
     
         9 . The ink for ink jet recording of  claim 2 , comprising the surface tension of 30 to 50 mN/m.  
     
     
         10 . The ink for ink jet recording of  claim 2 , wherein the viscosity of the ink at 30° C. is 30 to 300 mPa·s.  
     
     
         11 . The ink of  claim 2 , wherein the ink has a viscosity of 7 to 30 mPa·s at 70° C.  
     
     
         12 . The ink for ink jet recording of  claim 3 , wherein the white pigment is a titanium oxide, the viscosity of the ink at 30° C. is 30 to 300 mPa·s, and the ink includes a polymerization inhibitor.  
     
     
         13 . An image forming method comprising the steps of: heating an ink in an ink-jet head so as to be not less than 40° C., and jetting the ink through an ink-jet head nozzle, wherein the ink has a viscosity of 10 to 500 mPa·s at 30° C., and has a viscosity of 7 to 30 mPa·s after heating to be not less than 40° C.  
     
     
         14 . The method of  claim 13 , wherein when recording is carried out on a recording medium under performing a tone reproduction method with a white ink and a colored ink, the transmission density of a white ink layer on the recording medium is at least 0.15 and the L value thereof is at least 65.  
     
     
         15 . The method of  claim 14 , wherein said tone reproduction method is an error diffusion method.  
     
     
         16 . The method of  claim 14 , wherein said tone reproduction method is a dither method.  
     
     
         17 . The method of  claim 14 , wherein said reproduction method are performed with a plurality of colored inks having the same color at different densities.  
     
     
         18 . The method of  claim 14 , wherein said tone reproduction method are performed with a dot diameter which is varied at a plurality of levels.  
     
     
         19 . The method of  claim 14 , wherein the recording medium is transparent.  
     
     
         20 . A method for producing a material by ink jet apparatus comprising the step of: jetting an ink onto an ink-jet recording medium, wherein the ink comprises a viscosity of 10 to 500 Pa·s at 30° C., and a viscosity of 7 to 30 mPa·s at a temperature which is same or vicinity of a temperature of an ink jet head nozzle when jetting.  
     
     
         21 . The method for ink jet recording of  claim 20 , wherein the ink comprises the viscosity from 7 to 30 mPa·s at the temperature of the ink jet head nozzle ±2° C. when jetting.