Stable non-aqueous inkjet inks

1. A non-aqueous ink not curable by UV radiation comprising:

an organic color pigment; and

a dispersion medium including between 12 wt % to 98 wt % of tetraethylene glycol dimethylether based on the total weight of the ink; wherein

either the dispersion medium consists of tetraethylene glycol dimethylether or the tetraethylene glycol dimethylether is present as part of a mixture of polyalkyleneglycol dialkylethers in the dispersion medium.

2. The non-aqueous ink according to claim 1 , wherein the tetraethylene glycol dimethylether includes at least 25 wt % based on the total weight of the ink.

3. The non-aqueous ink according to claim 1 , wherein the organic color pigment is C.I. Pigment Blue 15.

4. The non-aqueous ink according to claim 1 , wherein the organic color pigment is C.I. Pigment Yellow 150.

5. The non-aqueous ink according to claim 1 , wherein the ink has a dispersion synergist deposited on a surface of the organic color pigment.

6. The non-aqueous ink according to claim 1 , wherein the ink is an inkjet ink having a viscosity of less than 30 mPa·s measured at a shear rate of 100 s −1 and a jetting temperature between 10° C. and 70° C.

7. A non-aqueous inkjet ink set comprising:

at least two non-aqueous inkjet inks according to claim 6 .

8. A method for preparing the non-aqueous inkjet ink not curable by UV radiation according to claim 1 , the method comprising the steps of:

a) preparing a pigment dispersion by mixing the organic color pigment and a solvent including the tetraethylene glycol dimethylether; and

b) diluting the pigment dispersion of step a) with a non-aqueous solvent to obtain a pigment concentration between 0.1 wt % and 20 wt % based upon the total weight of the inkjet ink.

9. The method according to claim 8 , wherein the pigment dispersion of step a) includes at least 15 wt % of tetraethylene glycol dimethylether based on the total weight of the pigment dispersion.

10. The non-aqueous ink according to claim 1 , wherein the mixture of polyalkyleneglycol dialkylethers is a mixture of polyethylene glycol dimethyl ethers having a molecular weight of at least 200.

11. The non-aqueous ink according to claim 1 , wherein the mixture of polyalkyleneglycol dialkylethers has an average molecular weight between 200 and 800.

12. The non-aqueous ink according to claim 11 , wherein no polyalkyleneglycol dialkylethers with a molecular weight of more than 800 are present.