Aqueous ink compositions
This invention relates to aqueous ink compositions comprising an aqueous solvent, particles comprising a metal or a metal compound or a mixture thereof, a dispersant, preferably selected from an electrostatic dispersant, a steric dispersant, an ionic dispersant, a non-ionic dispersant or a combination thereof, a polymeric binder and a non-ionic surfactant which may be used for 3D inkjet printing components, primarily for high-temperature electrochemical devices.
1. An aqueous ink composition comprising:
an aqueous solvent;
particles comprising a metal or a metal compound or a mixture thereof;
a dispersant, wherein the dispersant is an electrostatic dispersant and is present at an amount of 0.1 to 1 mg m −2 of the surface area of the particles;
a polymeric binder; and
a non-ionic surfactant.
2. The aqueous ink composition of claim 1 , wherein the particles comprise a metal oxide.
3. The aqueous ink composition of claim 1 , wherein the particles comprise zirconium, yttrium, lanthanum, strontium, manganese, nickel, cobalt, cerium, silver or gadolinium or mixtures thereof.
4. The aqueous ink composition of claim 1 , wherein the particles comprise yttria-stabilised zirconia (YSZ), lanthanum nickelates, lanthanum strontium manganite (LSM), lanthanum cobaltites, gadolinium doped ceria (GDC), nickel oxide or silver oxide, or mixtures thereof.
5. The aqueous ink composition of claim 1 , wherein the particles comprise yttria-stabilised zirconia (YSZ).
6. The aqueous ink composition of claim 1 , wherein the particles comprising a metal or a metal compound or a mixture thereof have an average particle diameter of about 1000 nm or less.
7. The aqueous ink composition of claim 1 , wherein the dispersant is an ammonium salt of an acrylic polymer, or wherein the composition further comprises a steric dispersant, an ionic dispersant, a non-ionic dispersant or a combination thereof.
8. The aqueous ink composition of claim 1 , wherein the electrostatic dispersant is present at an amount of about 0.2 to about 0.8 mg m −2 of the surface area of the particles comprising a metal or a metal compound or a mixture thereof, or wherein the dispersant is a steric dispersant and is present at an amount of about 10 to about 300 mg m −2 of the surface area of the particles comprising a metal or a metal compound or a mixture thereof.
9. The aqueous ink composition of claim 1 , wherein the polymeric binder is present in the aqueous ink composition at a concentration of about 10 to about 50 mg cm −3 .
10. The aqueous ink composition of claim 1 , wherein the non-ionic surfactant is present in the aqueous ink composition at a concentration of about 0.1 to about 0.5 mg cm −3 .
11. The aqueous ink composition of claim 1 having a dynamic viscosity of about 2 to about 20 mPa s.
12. The aqueous ink composition of claim 1 having a critical cracking thickness of at least 10 μm.
13. The aqueous ink composition of claim 1 ,
wherein the particles comprise yttria-stabilised zirconia (YSZ), lanthanum nickelates, lanthanum strontium manganite (LSM), lanthanum cobaltites, gadolinium doped ceria (GDC), nickel oxide or silver oxide, or mixtures thereof;
wherein the dispersant is an electrostatic dispersant present at an amount of about 0.1 to about 1 mg m −2 of the surface area of the particles comprising a metal or a metal compound or a mixture thereof; and
wherein the particles comprising a metal or a metal compound or a mixture thereof have an average particle diameter of about 1000 nm or less.
14. An article obtainable by printing an aqueous ink composition of claim 1 .
15. A method of preparing an aqueous ink composition according to claim 1 comprising the steps of:
(a) providing an aqueous solvent and adding a dispersant to the aqueous solvent;
(b) dispersing particles comprising a metal or a metal compound or a mixture thereof in the aqueous solvent; and
(c) adding a polymeric binder and a non-ionic surfactant to the aqueous dispersion.
16. The method of claim 15 , wherein step (b) is carried out after step (a).
17. The method of claim 15 , further comprising the step of concentrating the aqueous dispersion by removal of the aqueous solvent before adding the polymeric binder and the non-ionic surfactant.
18. The method of claim 15 , wherein the particles comprising a metal or a metal compound or a mixture thereof are dispersed in the aqueous solvent by sonication.
19. The method of claim 15 , further comprising the step of narrowing the particle size distribution after dispersing the particles comprising a metal or a metal compound or a mixture thereof in the aqueous solvent.
20. A method of producing a printed article comprising the steps of:
(a) providing a substrate;
(b) printing the aqueous ink composition of claim 1 onto the substrate to form a printed article; optionally
(c) drying the printed article; and optionally
(d) heat treating the printed article.
21. The method according to claim 20 , wherein the method further comprises the step of preparing the aqueous ink composition, prior to step (b).
22. The method according to claim 20 , wherein the step of printing the aqueous ink composition comprises printing a layer on the substrate of a thickness of about 1 to about 500 μm.
23. The method according to claim 20 , wherein the substrate is an electrode in a solid oxide fuel cell or a solid oxide electrolyser.