Inkjet dyes exhibiting reduced kogation
A salt of a sulfonated dye comprising an ammonium cation as a counterion. The ammonium cation comprises at least 3 hydroxyl groups. The salt is useful in reducing kogation in thermal inkjet printheads. One example of these salts is the compound of formula (II): wherein M is Ga(OH); and each of Z 1 + , Z 2 + , Z 3 + and Z 4 + is protonated 2,2-bis(hydroxymethyl)-2,2′,2″-nitrilotriethanol.
1. A salt of a sulfonated dye comprising at least one ammonium cation as a counterion, wherein the or each ammonium cation comprises at least 5 hydroxyl groups.
2. The salt of claim 1 , wherein the ammonium cation is of formula (A):
wherein:
R 5 , R 6 , R 7 , R 8 , R 9 and R 10 are each independently selected from the group consisting of: H and —CH 2 OH.
3. The salt of claim 1 , wherein the ammonium cation is protonated 2,2-bis(hydroxymethyl)-2,2′,2″-nitrilotriethanol.
4. The salt of claim 1 , wherein said dye is a sulfonated phthalocyanine dye.
5. The salt of claim 1 , wherein said dye is an IR-absorbing dye.
6. The salt of claim 1 , which is of formula (I):
wherein:
Q 1 , Q 2 , Q 3 and Q 4 are the same or different and are independently selected from the group consisting of: a C 3-20 arylene group and a C 3-20 heteroarylene group;
M is (H 2 ) or a metal 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: —OH, halogen, —OR 3 , —OC(O)R 4 and —O(CH 2 CH 2 O) e R e wherein e is an integer from 2 to 10 and R e is H, C 1-8 alkyl or —C(O)C 1-8 alkyl;
R 3 is C 1-20 alkyl, C 5-12 aryl, C 5-20 arylalkyl or Si(R x )(R y )(R z );
R 4 is C 1-20 alkyl, C 5-12 aryl or C 5-20 arylalkyl;
R x , R y and R z are 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; and
Z 1 + , Z 2 + , Z 3 + and Z 4 + are independently selected from the group consisting of: H and an ammonium cation comprising at least 5 hydroxyl groups, wherein at least one of Z 1 + , Z 2 + , Z 3 + and Z 4 + is said ammonium cation.
7. The salt of claim 1 , which is of formula (II):
wherein
M is (H 2 ) or a metal 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 is an axial ligand selected from the group consisting of: —OH, halogen, —OR 3 , —OC(O)R 4 and —O(CH 2 CH 2 O) e R e wherein e is an integer from 2 to 10 and R e is H, C 1-8 alkyl or C(O)C 1-8 alkyl;
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 );
R 4 is selected from the group consisting of: C 1-12 alkyl, C 5-12 aryl and C 5-12 arylalkyl;
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; and
Z 1 + , Z 2 + , Z 3 + and Z 4 + are independently selected from the group consisting of: H and an ammonium cation comprising at least 5 hydroxyl groups, wherein at least one of Z 1 + , Z 2 + , Z 3 + and Z 4 + is said ammonium cation.
8. The salt of claim 7 , wherein at least three of Z 1 + , Z 2 + , Z 3 + and Z 4 + are said ammonium cation.
9. An inkjet ink comprising a salt according to claim 1 .
10. A method of reducing kogation in an inkjet printhead, said method comprising: printing from the printhead utilizing an inkjet ink according to claim 9 .
11. The method of claim 10 , wherein said printhead comprises a plurality of nozzles, each nozzle comprising: a nozzle chamber containing said ink; a heater element for heating said ink; and a nozzle opening for ejection of ink.
12. The method of claim 11 , wherein said heater element is comprised of titanium nitride or a nitride of a titanium alloy.
13. The method of claim 12 , wherein said heater element is comprised of titanium aluminium nitride.
14. The method of claim 11 , wherein said heater element is a cantilever beam suspended across said nozzle chamber.
15. The method of claim 10 , wherein said printing includes at least 50 million drop actuations.
16. An inkjet printhead comprising a plurality of nozzles, each nozzle comprising: a nozzle chamber containing an inkjet ink according to claim 9 ; a heater element for heating said ink; and a nozzle opening for ejection of ink.
17. The inkjet printhead of claim 16 , wherein said heater element is comprised of titanium aluminium nitride.
18. A substrate having a salt according to claim 1 disposed thereon or therein.