Ink comprising silver nanoparticles
The present invention relates to ink formulations based on silver nanoparticles. In particular, the present invention relates to ink formulations based on silver nanoparticles, said inks being stable, with improved conductivity and particularly suitable for the field of contactless inkjet printing.
1. An ink composition comprising
1. one compound “a” consisting of silver nanoparticles,
2. one compound “e” consisting of a mixture of solvents, and
3. one compound “W” consisting of water, wherein
A. compound “a” constitutes at least 10% by weight of the ink composition,
B. compound “e” constitutes at least 55% by weight of the ink composition and consists of
B.1. at least one aliphatic monohydric alcohol, and
B.2. at least one terpenic alcohol, and
B.3. at least one polyol and/or one polyol derivative, and
C. compound “W” constitutes at least 2.5% by weight of the ink composition, and
D. the sum of compounds “a”, “e” and “W” constitutes at least 80% by weight of the ink composition.
2. The ink composition according to claim 1 , in which the water concentration is at least 4% by weight and is less than 10% by weight.
3. The ink composition according to claim 1 , in which the concentration of silver nanoparticles is between 15% and 25% by weight.
4. The ink composition according to claim 1 , in which the concentration of aliphatic monohydric alcohol is at least 10% by weight and is less than 20% by weight.
5. The ink composition according to claim 1 , in which the concentration of terpenic alcohol is at least 15% by weight and is less than 30% by weight.
6. The ink composition according to claim 1 , in which the concentration of polyol and polyol derivative is at least 30% by weight and is less than 45% by weight.
7. The ink composition according to claim 1 , in which the aliphatic monohydric alcohol is selected from the group consisting of ethanol, propanol, butanol, pentanoland, hexanoland, isopropanol, n-butanol, tert-butanol, and/or a mixture of two or more of said abovementioned aliphatic monohydric alcohols.
8. The ink composition according to claim 1 , in which the terpenic alcohol is selected from menthol, nerol, cineol, lavandulol, myrcenol, terpineol, alpha-terpineol, beta-terpineol, gamma-terpineol, and/or terpinen-4-ol, isoborneol, citronellol, linalool, borneol, geraniol, and/or a mixture of two or more of said abovementioned alcohols.
9. The ink composition according to claim 1 , in which the polyol and/or polyol derivative has a boiling point of less than 260° C.
10. The ink composition according to claim 1 , in which the polyol is a glycol and the polyol derivative is a glycol ether.
11. The ink composition according to claim 1 , in which the polyol is absent and the polyol derivative consists of a mixture of glycol ethers.
12. The ink composition according to claim 11 , wherein the polyol derivative comprises 2-(2-(2-methoxyethoxy)ethoxy)ethanol and 2-(2-butoxyethoxy)ethan-1-ol.
13. The ink composition according to claim 1 , comprising a compound “p” consisting of an adhesion promoter selected from acrylic polymers, silanes, siloxanes and/or polysiloxanes and the concentration of which is between 0.1% and 5% by weight.
14. The ink composition according to claim 1 , having a viscosity measured at 20° C. of between 5 and 25 mPa·s.
15. The ink composition according to claim 1 , characterized in that the silver nanoparticles (compound “a”) are spheroidal and have D50 values of between 10 and 150 nm.
16. The ink composition according to claim 1 , wherein the ink is used in contactless inkjet printing.