White ink

Abstract

An ink comprising: (a) from 1 to 20 parts of surface treated titanium dioxide; (b) from 20 to 70 parts of viscosity modifier; (c) from 5 to 30 parts of one or more water miscible polar organic solvent(s); (d) from 0.1 to 3 parts of surfactant; (e) from 0.001 to 5 parts of biocide; (f) from 0 to 20 parts of polymer particles; (g) the balance to 100 parts water; wherein the ink has a viscosity in the range of from 10 to 25 mPa.Math.s when measured at 32° C. using a Brookfield spindle SOO at 3 or 12 rpm depending on whether the viscosity is < or >16 mPa.Math.s. Also ink jet printing processes, printed substrates, ink containers and ink-jet printers.

Claims

1. An ink comprising: (a) from 1 to 20 parts of surface treated titanium dioxide; (b) from 20 to 70 parts of viscosity modifier; (c) from 5 to 30 parts of one or more water miscible polar organic solvent(s); (d) from 0.1 to 3 parts of surfactant; (e) from 0.001 to 5 parts of biocide; (f) from 0 to 20 parts of polymer particles; (g) the balance to 100 parts water; wherein the ink has a viscosity in the range of from 10 to 25 mPa.Math.s when measured at 32° C. utilizing a Brookfield spindle S00 at 3 or 12 rpm depending on whether the viscosity is < or >16 mPa.Math.s.

2. The ink as claimed in claim 1 wherein the surface of the surface treated titanium dioxide is coated with an inorganic compound selected from the group consisting of silica, alumina, alumina-silica or zirconia.

3. The ink as claimed in claim 1 wherein the surface of the surface treated titanium dioxide is treated with alumina, silica or a mixture thereof.

4. The ink as claimed in claim 1 wherein component (b) comprises from 20 to 60 parts of glycerol or a mixture of glycerol and polyethylene glycol.

5. The ink as claimed in claim 1 wherein component (c) comprises 1 to 3 solvents selected from the group consisting of 2-pyrrolidone, ethylene glycol and diethylene glycol.

6. The ink as claimed in claim 1 wherein component (d) comprises an acetylenic surfactant.

7. The ink as claimed in claim 1 comprising: (i) from 1 to 12 parts of surface treated titanium dioxide; (ii) from 20 to 60 parts of glycerol or a mixture of glycerol and polyethylene glycol; (iii) from 5 to 20 parts of water miscible organic solvent consisting of 1 to 3 solvents selected from the group consisting of 2-pyrrolidone, ethylene glycol and diethylene glycol; (iv) from 0.05 to 1.5 parts of an acetylenic surfactant; (v) from 1 to 12 parts of polymer particles; (vi) the balance to 100 parts water; and wherein the ink has a viscosity in the range of from 10 to 20 mPa.Math.s when measured at 32° C. utilizing a Brookfield spindle S00 at 3 or 12 rpm depending on whether the viscosity is < or >16 mPa.Math.s.

8. An ink-jet printing process wherein the ink according to claim 1 is printed onto a substrate by means of an ink jet printer.

9. A substrate printed by an ink-jet printing process according to claim 8 utilizing an ink comprising (a) from 1 to 20 parts of surface treated titanium dioxide; (b) from 20 to 70 parts of viscosity modifier; (c) from 5 to 30 parts of one or more water miscible polar organic solvent(s); (d) from 0.1 to 3 parts of surfactant; (e) from 0.001 to 5 parts of biocide; (f) from 0 to 20 parts of polymer particles; (g) the balance to 100 parts water; wherein the ink has a viscosity in the range of from 10 to 25 mPa.Math.s when measured at 32° C. utilizing a Brookfield spindle S00 at 3 or 12 rpm depending on whether the viscosity is < or >16 mPa.Math.s.

10. An ink-jet printer ink container containing an ink according to claim 1.

11. An ink-jet printer with re-circulating printer head containing an ink according to claim 1.

Description

EXAMPLES 1 AND 2

Composition of Example Inks 1 and 2

(1) Example inks 1 and 2 were prepared by mixing all the components except the titanium dioxide dispersion. The pH was measured and adjusted to pH 8.0 to 8.3 with 5% ammonium hydroxide solution to give a pre-ink mixture. The titanium dioxide dispersion was diluted with a small amount of the pre-ink mixture and then was slowly added to the pigment dispersion. The pH was again measured and adjusted if it had fallen below 8.0. The resulting ink was filtered through a 1.0 micron syringe filter.

(2) TABLE-US-00001 Component Example Ink 1 Example Ink 2 Titanium Dioxide 8 8 Ethylene Glycol 10 10 Surfynol 465 0.6 0.4 Glycerol 30 50 2-Pyrrolidone 5 5 PEG 20,000 2.65 0 Proxel GXL 0.02 0.02 Water To 100 parts To 100 parts

(3) The surface treated titanium dioxide was GLW75PFSP from Kobo Products.

Properties of Example Inks 1 and 2

(4) TABLE-US-00002 Property Example Ink 1 Example Ink 2 Surface Tension (dyne/cm) 34 34.1 Viscosity (mPa .Math. s) 14.9 13.5 Density(g/cm.sup.3) 1.163 1.207 Conductivity 0.048 0.022 Particle size (nm) 290 290

(5) The surface tension was measured at 25° C. using a Kruss K-11 Tensiometer (Wilhelmy Plate Method).

(6) Viscosity was measured at 32° C. using a Brookfield DV-II or DV-II+ digital viscometer with UL-adapter and water jacket and spindle S00 at 3 or 12 rpm depending on whether the viscosity is < or >16 mPa.Math.s.

(7) Density (specific gravity) of the ink was measured using a pycnometer.

(8) Conductivity was measured using an Orion conductivity meter.

(9) Particle size was measured using a Zetasizer from Malvern Instruments.

Stability of Example Inks 1 and 2

(10) Ink samples were stored for 4 weeks at RT, 40° C. and 60° C. After each week colloidal stability with respect to pH, viscosity, particle size by dynamic light scattering (DLS), sedimentation by backscattering light (Turbiscan®) as well as re-dispersability testing were carried out. The inks demonstrated remarkable stability with respect to particle size and re-dispersability. Downward drift in pH and upward trend in viscosity were observed at elevated temperature. In a separate experiment an accelerated shelf-life study was conducted by storing samples at RT, 40° C. and 60° C. for 6 weeks. Samples were removed every other week and characterized for pH, surface tension, conductivity, particle size and viscosity. Measurements indicate samples showed minimum variability. It is expected that the ink will have a shelf-life of about 12 months with little or no agitation.

(11) Printing of Example Inks 1 and 2

(12) Example inks 1 and 2 were filtered through a 1.0 micron syringe filter (for small ink samples ˜ up to 300 g) or through a Chipwich filter (for sample volume up to 1.0 L or more) and then added to individual ink cartridges. The cartridges were conditioned overnight before being installed in a printer and printed onto 10 pages of coloured paper or ink-jet transparency. In both cases the jetting performance of the printer was acceptable.

EXAMPLES 3 TO 16

(13) TABLE-US-00003 Component Example Ink 3 Example Ink 4 Titanium Dioxide 12.00 12.00 Ethylene Glycol 10.00 10.00 Chemguard S-103A 0.06 Dynol 810 0.19 Glycerol 20.00 20.00 2-Pyrrolidone 5.00 5.00 PEG 20,000 2.00 2.00 NeoAcryl A2980 8.00 8.00 Proxel GXL 0.02 0.02 Water To 100 parts To 100 parts

(14) TABLE-US-00004 Component Example Ink 5 Example Ink 6 Titanium Dioxide 12.00 12.00 Ethylene Glycol 10.00 10.00 Dynol 810 0.19 0.30 Glycerol 20.00 30.00 2-Pyrrolidone 5.00 5.00 PEG 20,000 2.00 2.00 Rovene 6102 6.00 NeoRez R551 3.00 Rovene 5499 3.00 Proxel GXL 0.02 0.02 Water To 100 parts To 100 parts

(15) TABLE-US-00005 Component Example Ink 7 Example Ink 8 Titanium Dioxide 12.00 12.00 Ethylene Glycol 10.00 10.00 Dynol 810 0.19 Chemguard S-103A 0.06 Glycerol 20.00 20.00 2-Pyrrolidone 5.00 5.00 PEG 20,000 2.00 2.00 Rovene 6102 8.00 NeoAcryl A2980 5.60 NeoRez R551 2.40 Proxel GXL 0.02 0.02 Water To 100 parts To 100 parts

(16) TABLE-US-00006 Component Example Ink 9 Example Ink 10 Titanium Dioxide 12.00 12.00 Ethylene Glycol 10.00 10.00 Dynol 810 0.15 Chemguard S-103A 0.06 Glycerol 26.00 26.00 2-Pyrrolidone 5.00 5.00 PEG 20,000 2.00 2.00 NeoAcryl A2980 4.00 4.00 Proxel GXL 0.02 0.02 Water To 100 parts To 100 parts

(17) TABLE-US-00007 Component Example Ink 11 Example Ink 12 Titanium Dioxide 12.00 8.00 Ethylene Glycol 10.00 10.00 Chemguard S-103A 0.05 0.06 Glycerol 24.00 30.00 2-Pyrrolidone 5.00 5.00 PEG 20,000 2.00 2.00 NeoAcryl A2980 2.00 4.00 NeoRez R551 3.00 Proxel GXL 0.02 0.02 Water To 100 parts To 100 parts

(18) TABLE-US-00008 Component Example Ink 13 Example Ink 14 Titanium Dioxide 12.00 12.00 Ethylene Glycol 10.00 10.00 Dynol 810 0.05 Chemguard S-103A 0.05 Triton HW-1000 0.22 Glycerol 26.00 26.00 2-Pyrrolidone 5.00 5.00 PEG 20,000 2.00 2.00 NeoAcryl A2980 4.00 4.00 Proxel GXL 0.02 0.02 Water To 100 parts To 100 parts

(19) TABLE-US-00009 Component Example Ink 15 Example Ink 16 Titanium Dioxide 12.00 12.00 Ethylene Glycol 10.00 10.00 Surfynol 465 1.00 Dynol 810 0.51 Glycerol 25.00 24.00 2-Pyrrolidone 5.00 5.00 PEG 20,000 2.00 2.00 NeoAcryl A2980 4.00 NeoRez R600 4.00 Proxel GXL 0.02 0.02 Water To 100 parts To 100 parts Surfynol® 465 is an ethoxylated acetylenic surfactant from Air Products. Dynol® 810 is an ethoxylated acetylenic surfactant from Air Products. Chemguard S-103A is a short-chain perfluoro-based anionic fluorosurfactant from Chemguard. NeoRez® R551 is a polyurethane dispersion from Neo Resins. NeoRez R600 is a polyurethane dispersion from Neo Resins. NeoCryl® A2980 is an acrylic dispersion from Neo Resins.

(20) Incorez W835/177 is a polyurethane dispersion from Incorez. The glass transition temperature (Tg) of Incorez W835/177 was determined by means of differential scanning calorimetry and was found to be −15.3° C.

(21) Rovene® 5499 is a styrene butadiene dispersion from Mallard Creek Polymers. The Tg of Rovene 5499 is 0° C.

(22) Rovene® 6102 is a styrene acrylic dispersion from Mallard Creek Polymers. The Tg of Rovene 6102 is 20° C.

(23) Proxel® GXL is a 20% solution of 1,2-benzisothazolin-3-one in dipropylene glycol from Lonza.

(24) TABLE-US-00010 Surface Tension Viscosity at 32° C. Example Ink pH dynes/cm mPa .Math. s 3 8.5 36.4 ND 4 8.5 35 12.6 5 ND 34.6 12.8 7 ND 35 ND 8 8.5 33.9 12.6 9 8.5 36.6 12.4 10 8.6 35.6 12.3 11 8.6 35.1 12.8 12 8.5 35.1 12.4 13 8.5 33.2 12.9 14 8.6 33.6 12.8 15 8.5 33.9 12.5 16 8.4 33.8 12.0 *ND = not determined.

(25) Inks 3 and 8 to 16 were printed through a StarFire® SG1024 re-circulating print head from Fujifilm Dimatix. All inks printed without any problems to give high quality prints.