Ink composition including polyurethane
According to one aspect, an ink composition includes a colorant, a polyurethane having a peak average molecular weight range of from about 25,000 g/mol to about 35,000 g/mol, and a solvent. The ink composition has a total solids content of less than about 12% by weight, and a ratio of colorant to polyurethane between about 1:1 and 1:2 by weight.
1. An ink composition comprising: a colorant, a polyurethane having a peak molecular weight range of from about 25,000 g/mol to about 35,000 g/mol, and a solvent, wherein the ink composition has a total solids content of less than about 15% by weight, and has a ratio of colorant to polyurethane between about 2:1 and 1:2 by weight, and wherein the ink composition has a viscosity between about 1 and about 20 cP, and wherein the polyurethane is present in an amount from about 2.9% to about 5.67% solids.
2. The ink composition of claim 1 wherein the colorant is present in an amount from about 2.0% to about 7.5% solids.
3. The ink composition of claim 1 wherein the solvent is water.
4. The ink composition of claim 3 wherein the solvent additionally includes a humectant.
5. The ink composition of claim 1 wherein the composition also includes at least one surface active agent.
6. The ink composition of claim 1 wherein the composition also includes a viscosity modifying agent.
7. The ink composition of claim 1 wherein the composition has a viscosity of from about 4.0 to about 6.0 cP.
8. The ink composition of claim 1 wherein the polyurethane has an acid number of between about 15 to about 25.
9. A method of printing using an ink jet print head comprising the step of jetting an ink composition onto a substrate, wherein the ink composition comprises a colorant, a polyurethane having a peak molecular weight range of from about 25,000 g/mol to about 35,000 g/mol, and a solvent, wherein the ink composition has a total solids content of less than about 15% by weight, and has a ratio of colorant to polyurethane between about 2:1 and 1:2 by weight, and wherein the ink composition has a viscosity between about 1 and about 20 cP, and wherein the polyurethane is present in an amount from about 2.9% to about 5.67% solids.
10. The method of claim 9 wherein the colorant is present in an amount from about 2.9% to about 7.5% solids.
11. The method of claim 9 wherein the solvent is water.
12. The method of claim 11 wherein the solvent additionally includes a humectant.
13. The method of claim 9 wherein the composition also includes at least one surface active agent.
14. The method of claim 9 wherein the composition also includes a viscosity modifying agent.
15. The method of claim 9 wherein the composition has a viscosity of from about 4.0 to about 6.0 cP.
16. The method of claim 9 wherein the polyurethane has an acid number of between about 15 to about 25.