Inkjet inks for printing coded data comprising naphthalocyanine dyes

1. An inkjet ink comprising an IR-absorbing naphthalocyanine dye of formula (I):

wherein

M is selected from the group consisting of: Si(A 1 )(A 2 ), Ge(A 1 )(A 2 ), Ga(A 1 ), Mg, Al(A 1 ), TiO, Ti(A 1 )(A 2 ), ZrO, Zr(A 1 )(A 2 ), VO, V(A 1 )(A 2 ), Mn, Mn(A 1 ), Fe, Fe(A 1 ), Co, Ni, Cu, Zn, Sn, Sn(A 1 )(A 2 ), Pb, Pb(A 1 )(A 2 ), Pd and Pt;

A 1 and A 2 are axial ligands, which may be the same or different, and are selected from the group consisting of{tilde over (:)} OH, halogen and {tilde over ( )} OR 3 ;

R 1 and R 2 are selected from the group consisting of: H and C 1-12 alkoxy;

R 3 is selected from the group consisting of: C 1-12 alkyl, C 5-12 aryl, C 5-12 arylalkyl and Si(R x )(R y )(R z ); and

R x , R y and R z may be the same or different and are selected from the group consisting of:

C 1-12 alkyl, C 5-12 aryl, C 5-12 arylalkyl, C 1-12 alkoxy, C 5-12 aryloxy and C 5-12 arylalkoxy;

W is selected from the group consisting of: a sulfonic acid group or a salt thereof; and a sulfonamide group;

n1 is 0, 1, 2 or 3;

n2 is 0, 1, 2 or 3;

n3 is 0, 1, 2 or 3;

n4 is 0, 1, 2 or 3;

provided that at least one of n1, n2, n3 or n4 is greater than 0.

2. The ink of claim 1 , wherein W is selected from the group consisting of{tilde over (:)} SO 3 H and —SO 3 Z, and wherein Z is Li, Na or K.

3. The ink of claim 1 , wherein R 1 and R 2 are both H.

4. The ink of claim 1 , wherein M is selected from the group consisting of: Si(A 1 )(A 2 ), Ge(A 1 )(A 2 ), Ga(A 1 ), Al(A 1 ), Mn(A 1 ), Fe(A 1 ) and Sn(A 1 )(A 2 ).

5. The ink of claim 1 , wherein A 1 and A 2 are each independently selected from the group consisting of: Cl and OH.