Stable non-aqueous inkjet inks

1. A non-aqueous inkjet ink comprising:

a pigment; and

a mixture of at least two polyalkyleneglycol dialkylethers represented by Formula (I):

wherein;

R 1 and R 2 are each independently selected from an alkyl group having 1 to 4 carbon atoms;

Y represents an ethylene group or a propylene group;

n is an integer selected from 4 to 20 for a first polyalkyleneglycol dialkylether; and n is an integer selected from 5 to 20 for a second polyalkyleneglycol dialkylether.

2. The non-aqueous inkjet ink according to claim 1 , wherein the mixture includes a third polyalkyleneglycol dialkylether according to Formula (I) having the integer n selected from 4 to 20.

3. The non-aqueous inkjet ink according to claim 2 , wherein the third polyalkyleneglycol dialkylether has the integer n selected from 6 to 20.

4. The non-aqueous inkjet ink according to claim 1 , wherein the polyalkyleneglycol dialkylethers are polyethyleneglycol dialkylethers.

5. The non-aqueous inkjet ink according to claim 1 , wherein R 1 and R 2 represent methyl and/or ethyl.

6. The non-aqueous inkjet ink according to claim 1 , wherein the mixture of polyalkyleneglycol dialkylethers represented by Formula (I) includes at least one polyalkyleneglycol dialkyl ether wherein the integer n is equal to 6.

7. The non-aqueous inkjet ink according to claim 1 , further comprising a polyalkyleneglycol derivative selected from the group consisting of polyalkyleneglycol monoalkyl ether acetates and polyalkyleneglycol monoalkyl ethers.

8. The non-aqueous inkjet ink according to claim 7 , wherein the polyalkyleneglycol monoalkyl ether acetate is selected from the group consisting of dipropyleneglycol monomethyl ether acetate and diethyleneglycol monobutyl ether acetate.

9. The non-aqueous inkjet ink according to claim 7 , wherein the polyalkyleneglycol monoalkyl ether is selected from the group consisting of triethyleneglycol monobutyl ether and tripropyleneglycol monomethylether.

10. The non-aqueous inkjet ink according to claim 7 , wherein the liquid component of the ink consists of one or more polyalkyleneglycol derivatives and the mixture of polyalkyleneglycol dialkylethers.

11. The non-aqueous inkjet ink according to claim 1 , further comprising a dispersion synergist.

12. The non-aqueous inkjet ink according to claim 1 , wherein the ink has a pigment concentration between 6 wt % and 15 wt % based upon the total weight of the ink.

13. The non-aqueous inkjet ink according to claim 1 , wherein the non-aqueous inkjet ink is a radiation curable inkjet ink.

14. An inkjet ink set comprising:

at least two non-aqueous inkjet inks according to claim 1 .

15. The inkjet ink set according to claim 14 , further comprising a non-aqueous inkjet ink including a diketopyrrolo-pyrrole pigment.

16. The inkjet ink set according to claim 15 , wherein the diketopyrrolo-pyrrole pigments are C.I. Pigment Red 254.

17. A method for preparing a non-aqueous inkjet ink comprising the steps of:

a) preparing a pigment dispersion by mixing a pigment and a solvent mixture including at least two polyalkyleneglycol dialkylethers represented by Formula (I):

wherein;

R 1 and R 2 are each independently selected from an alkyl group having 1 to 4 carbon atoms;

Y represents an ethylene group or a propylene group;

n is an integer selected from 4 to 20;

n is a different integer for the at least two polyalkyleneglycol dialkylethers; 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.