Ink formulations and film constructions thereof

Abstract

Ink formulations suitable for deposition upon the intermediate transfer member of an indirect printing system and for transfer therefrom to a substrate. The inks are aqueous inkjet inks comprising an organic polymeric resin and a colorant. Ink film constructions including a plurality of continuous ink films fixedly adhered to the printing substrate that can be obtained with these inks are also disclosed. The inks and the printed constructions are such that the ink films and the dried inks composing them have a first dynamic viscosity within a range of 10 6 cP to 5·10 7 cP at at least a first temperature within a first range of 60° C. to 87.5° C., and a second dynamic viscosity of at least 6·10 7 cP, for at least a second temperature within a second range of 50° C. to 55° C.

1 . A water-based ink formulation comprising:
 (a) a solvent containing water;   (b) at least one colorant dispersed or at least partly dissolved within the solvent; and   (c) at least one organic polymeric resin, dispersed within the solvent; and   (d) a softening agent selected to reduce a glass transition temperature (T g ) of said polymeric resin,   the ink formulation forming, when dried, a substantially dry ink residue having:   (i) a first dynamic viscosity within a range of 10 6  cP to 3·10 8  cP over at least part of a first temperature range of 60° C. to 110° C.; and   (ii) a second dynamic viscosity of at least 6·10 7  cP, over at least a part of a second temperature range of 50° C. to 55° C.;   said second dynamic viscosity at 55° C. exceeding the first dynamic viscosity at 85° C.;   said softening agent having a pure vapor pressure of at most 0.40 kPa at 150° C.   
     
     
         2 . The ink formulation of  claim 1 , said softening agent having a vapor pressure of at most 0.35 kPa, at most 0.25 kPa, at most 0.20 kPa, at most 0.15 kPa, at most 0.12 kPa, at most 0.10 kPa, at most 0.08 kPa, at most 0.06 kPa, or at most 0.05 kPa, at 150° C. 
     
     
         3 . The ink formulation of  claim 1 , at least one particular resin of said organic polymeric resin having an elevated glass transition temperature (T g ) of at least 50° C., at least 52° C., at least 54° C., at least 56° C., at least 58° C., at least 60° C., at least 65° C., at least 70° C., at least 75° C., at least 80° C., at least 85° C., at least 90° C., or at least 95° C. 
     
     
         4 . The ink formulation of  claim 3 , said softening agent selected and/or added in an amount to reduce said elevated glass transition temperature by at least 5° C., at least 7° C., at least 10° C., at least 15° C., at least 20° C., at least 25° C., at least 30° C., at least 40° C., or at least 50° C. 
     
     
         5 . The ink formulation of  claim 1 , said substantially dry ink residue has, at at least one of 100° C., 90° C., 85° C., 80° C., 75° C., and 70° C., an overall transferability rating of at least 0.90, at least 0.95, or 1.0. 
     
     
         6 . The ink formulation of  claim 3 , said softening agent selected and added in an amount such that said substantially dry ink residue has, at at least one of 100° C., 90° C., 85° C., 80° C., 75° C., and 70° C., an overall transferability rating of at least 0.90, at least 0.95, or 1.0. 
     
     
         7 . The ink formulation of  claim 1 , at least one polymeric resin of said at least one organic polymeric resin having a minimum film-forming temperature (MFFT) of at least 48° C., at least 50° C., at least 52° C., at least 54° C., at least 56° C., at least 58° C., at least 60° C., at least 65° C., at least 70° C., or at least 75° C. 
     
     
         8 . The ink formulation of  claim 1 , said first temperature range being 60° C. to 100° C. 
     
     
         9 . The ink formulation of  claim 1 , said first temperature range being 60° C. to 87.5° C., said first dynamic viscosity being within a range of 10 6  cP to 5·10 7  cP over at least part of said first temperature range. 
     
     
         10 . The ink formulation of  claim 1 , a weight ratio of said softening agent to said substantially dry ink residue being within a range of 0.01 to 0.25, 0.025 to 0.25, 0.04 to 0.25, 0.06 to 0.25, 0.08 to 0.25, 0.10 to 0.25, 0.10 to 0.20, or 0.12 to 0.20. 
     
     
         11 . The ink formulation of  claim 1 , the formulation being an aqueous inkjet ink having at least one of
 (i) a viscosity of 2 to 25 cP at at least one particular temperature in a jetting temperature range of 20-60° C.; and   (ii) a surface tension of at most 50 milliNewton/m at at least one particular temperature within said jetting temperature range.   
     
     
         12 . The ink formulation of  claim 1 , the formulation having a total solids content, and wherein a first weight ratio of said softening agent to said total solids content is at least 0.01, at least 0.02, at least 0.03, at least 0.04, at least 0.06, at least 0.08, or at least 0.10. 
     
     
         13 . The ink formulation of  claim 12 , said first weight ratio being at most 0.20, at most 0.15, at most 0.12, or at most 0.11. 
     
     
         14 . The ink formulation of  claim 1 , the formulation having a total resin content, and wherein a second weight ratio of said softening agent to said total resin content is at least 0.01, at least 0.02, at least 0.03, at least 0.04, at least 0.06, at least 0.08, at least 0.10, or at least 0.12. 
     
     
         15 . The ink formulation of  claim 14 , said second weight ratio being at most 0.25, at most 0.20, at most 0.15, or at most 0.13. 
     
     
         16 . The ink formulation of  claim 1 , the formulation having at least one high T g  resin having a T g  above 50° C., and wherein a third weight ratio of said softening agent to said at least one high T g  resin is at least 0.02, at least 0.04, at least 0.06, at least 0.08, at least 0.10, at least 0.12, at least 0.15, or at least 0.20. 
     
     
         17 . The ink formulation of  claim 16 , said third weight ratio being at most 1.0, at most 0.70, at most 0.50, at most 0.40, at most 0.30, at most 0.20, at most 0.17, at most 0.15, at most 0.12, or at most 0.10. 
     
     
         18 . The ink formulation of  claim 1 , wherein ΔT defines a temperature differential between a temperature (T F ) at which said dried ink residue begins to exhibit a particular degree of flowability, and a baseline temperature (T B ):
   Δ T=T   F   −T   B  
 
 said degree of flowability being defined by a critical viscosity (μ CR ) at which said degree of flowability is achieved, 
 and wherein, when said baseline temperature equals 50° C., and said critical viscosity equals 10 8  cP, said temperature differential is at least 3° C., at least 4° C., at least 5° C., at least 7° C., at least 12° C., at least 15° C., at least 18° C., at least 20° C., or at least 25° C. 
 
     
     
         19 . The ink formulation of  claim 1 , said polymeric resin including, mainly including, or consisting essentially of an acrylic-based polymer selected from the group consisting of an acrylic polymer and an acrylic-styrene copolymer. 
     
     
         20 . The ink formulation of  claim 1 , wherein at least one of the following is true:
 (a) the formulation adapted such that when diluted with water by at least 50%, at least 100%, at least 150%, at least 200%>, at least 250%, at least 300%>, at least 350%>, or at least 400%>, on a weight/weight basis by water, a resultant mixture is an aqueous inkjet ink having: (i) a viscosity of 2 to 25 cP at at least one particular temperature in a range of 20-60° C.; and (ii) a surface tension of at most 50 milliNewton/m at at least one particular temperature within said range; and   (b) a viscosity of said substantially dry ink residue monotonically increasing with temperature decreasing from 85° C. to 55° C.   
     
     
         21 . (canceled)