An ink including: (a) a metal chelate compound of Formula (1) or salt thereof, wherein M is nickel; and (b) a liquid medium. The inks are useful for ink jet printers.
1. An ink comprising:
(a) a metal chelate compound of Formula (1) or salt thereof, wherein M is nickel;
and (b) a liquid medium.
2. An ink according to claim 1 wherein the liquid medium comprises a mixture of water and an organic solvent.
3. An ink according to claim 1 or 2 comprising
(i) 1 to 10 parts of the compound of Formula (1) or salt thereof;
(ii) 2 to 60 parts of water-soluble organic solvent; and
(iii) 30 to 97 parts water;
wherein all parts are by weight and the sum of parts (i)+(ii)+(iii) =100.
4. A process for printing an image on a substrate comprising applying thereto by means of an ink jet printer an ink according to claim 1 or claim 2 .
5. A substrate printed with an ink according to claim 1 or 2 .
6. An ink jet printer cartridge comprising a chamber and ink, wherein the ink is present in the chamber and the ink is as defined in claim 1 or 2 .
7. An ink jet printer containing an ink printer cartridge, wherein the ink jet printer cartridge is as defined in claim 6 .
8. A process for printing an image on a substrate comprising applying thereto by means of an ink jet printer an ink according to claim 3 .
9. An ink jet printer cartridge comprising a chamber and ink, wherein the ink is present in the chamber and the ink is as defined in claim 3 .
10. An ink according to claim 1 or 2 which has a viscosity at 25° C. of less than 50 cP.
11. An ink according to claim 1 or 2 which has a viscosity at 25° C. of less than 5 cP.
12. An ink according to claim 1 or 2 wherein the compound of Formula (1) is in the form of a sodium, lithium, potassium, ammonium or substituted ammonium salt.
13. An ink according to claim 1 or 2 wherein the compound of Formula (1) has been purified by ultrafiltration, reverse osmosis and/or dialysis to remove undesirable impurities before incorporation into the ink for ink-jet printing.