Non-aqueous pigmented inkjet inks

1. A non-aqueous inkjet ink comprising:

a pigment including C.I. Pigment Violet 19; and

a polymeric dispersant according to Formula (I):

wherein

T represents hydrogen or a polymerization terminating group;

Z represents the residue of hyperbranched polyethyleneimine having a number-average molecular weight of at least 100;

A represents one or more oxyalkylene carbonyl groups selected from the group consisting of oxyalkylene carbonyl groups derivable from δ-valerolactone, ε-caprolactone, and C 1-4 -alkyl substituted ε-caprolactone;

T-C(O)A n - represents a TPOAC-chain which is bound to Z through an amide bond; and

n and m are integers wherein m is at least 2 and n is from 2 to 100; and

the polymeric dispersant satisfies the conditions of:

W TPOAC >57 and N Amide ≧65 mol %

wherein

W TPOAC represents a ratio of a weight percentage of the TPOAC-chains over a weight percentage of the amide bonds in the polymeric dispersant;

N Amide represents the mol % of the amide bonds based on a total nitrogen content of the polymeric dispersant; and

the values of W TPOAC and N Amide are calculated from the total nitrogen content determined by dry combustion of the polymeric dispersant and from the amine content determined through potentiometric titration in a mixture of CH 3 COOH:THF (14.5:0.5) with 0.1N aqueous perchloric acid.

2. The non-aqueous inkjet ink according to claim 1 , wherein the pigment including the C.I. Pigment Violet 19 is a mixed crystal.

3. The non-aqueous inkjet ink according to claim 1 , wherein the pigment consists of the C.I. Pigment Violet 19.

4. The non-aqueous inkjet ink according to claim 1 , wherein the chain moiety represented by -A n - is a mixture of oxyalkylene carbonyl groups derivable from δ-valerolactone and ε-caprolactone.

5. The non-aqueous inkjet ink according to claim 1 , wherein the mixture contains more than 75 mol % ε-caprolactone.

6. The non-aqueous inkjet ink according to claim 1 , wherein the alkyl substituent of C 1-4 alkyl substituted ε-caprolactone is methyl.

7. The non-aqueous inkjet ink according to claim 1 , wherein T is derived from a mono-carboxylic acid T-COOH selected from the group consisting of an aliphatic acid, an aromatic acid, a hetero-aromatic acid, a heterocyclic acid, and an alicyclic acid.

8. The non-aqueous inkjet ink according to claim 7 , wherein the aliphatic acid is a C 1-25 aliphatic carboxylic acid optionally substituted by hydroxyl, C 1-4 alkyl or halogen.

9. The non-aqueous inkjet ink according to claim 1 , further comprising a radiation curable compound.

10. A non-aqueous inkjet ink set comprising:

at least one non-aqueous inkjet ink including:

a pigment including C.I. Pigment Violet 19; and

a polymeric dispersant according to Formula (I):

wherein

T represents hydrogen or a polymerization terminating group;

Z represents the residue of hyperbranched polyethyleneimine having a number-average molecular weight of at least 100;

A represents one or more oxyalkylene carbonyl groups selected from the group consisting of oxyalkylene carbonyl groups derivable from δ-valerolactone, ε-caprolactone, and C 1-4 -alkyl substituted ε-caprolactone;

T-C(O)A n - represents a TPOAC-chain which is bound to Z through an amide bond; and

n and m are integers wherein m is at least 2 and n is from 2 to 100; and

the polymeric dispersant satisfies the conditions of:

W TPOAC >57 and N Amide ≧65 mol %

wherein

W TPOAC represents a ratio of a weight percentage of the TPOAC-chains over a weight percentage of the amide bonds in the polymeric dispersant;

N Amide represents the mol % of the amide bonds based on a total nitrogen content of the polymeric dispersant; and

the values of W TPOAC and N Amide are calculated from the total nitrogen content determined by dry combustion of the polymeric dispersant and from the amine content determined through potentiometric titration in a mixture of CH 3 COOH:THF (14.5:0.5) with 0.1N aqueous perchloric acid.