Writable and printable colloidal gold solution
View Patent ↗The present invention relates to an aqueous colloidal gold solution, comprising (a) nano-particular gold particles, (b) a compound having a polar tertiary amino group conjugated via a hydrophobic aromatic residue with a weaker alkaline group, and (c) a stabilizer comprising a mercapto group (—SH) and an acidic group, in particular a sulfonic acid group (—SO 3 − ). This gold solution uses an ecologically compatible medium and is suited in an especial manner for writing and for printing, also for inkjet printers, since it has a long-term storage life and generates an attractive metal-like gold sheen.
1. An aqueous colloidal gold solution comprising an aqueous medium and
(a) gold particles in colloidal form,
(b) a compound having a polar tertiary amino group conjugated via a hydrophobic aromatic residue with a weaker alkaline group which can also be a part of the aromatic residue, and
(c) a stabilizer comprising a mercapto group (—SH) and an acidic group,
wherein said solution has a gold content of 8 to 10% by weight.
2. An aqueous colloidal gold solution according to claim 1 , wherein the colloidal gold particles have an average diameter of 1 to 20 nm.
3. An aqueous colloidal gold solution according to claim 1 or 2 , wherein the aromatic residue of the compound (b) is a N-heteroaromatic residue with the nitrogen atom as weaker alkaline group.
4. An aqueous colloidal gold solution according to claim 3 , wherein the heteroaromatic residue is a pyridine residue.
5. An aqueous colloidal gold solution according to claim 4 , wherein the compound (b) is 4-dimethylamino-pyridine (DMAP).
6. An aqueous colloidal gold solution according to claim 1 , wherein the stabilizer (c) comprises a sulfonic acid group (—SO 3 − ).
7. An aqueous colloidal gold solution according to claim 6 , wherein the stabilizer (c) is a mercapto-(C 1−5 )-alkylsulfonic acid salt.
8. An aqueous colloidal gold solution according to claim 7 , wherein the stabilizer (c) is a 2-mercaptoethane sulfonic acid salt.
9. An aqueous colloidal gold solution according to claim 1 , comprising furthermore, as evaporation blocker,
(d) a polar organic compound with a vicinal dihydroxy group or an oligomer thereof.
10. An aqueous colloidal gold solution according to claim 9 , wherein the compound (d) is ethylene glycol.
11. An aqueous colloidal gold solution according to claim 1 , having the following composition:
(a) 8 to 10% by weight of the gold nanoparticles,
(b) 0.1 to 3% by weight of the compound having a tertiary amino group,
(c) 0.2 to 0.6% by weight of the stabilizer, and optionally
(d) 1 to 8% by weight of the evaporation blocker, each based on the total weight of the aqeous compostion.
12. An aqueous colloidal gold solution according to claim 1 , having a pH of 8 to 11.
13. Ink or printer cartridges containing the aqueous colloidal gold solution of claim 1 .
14. Printer cartridge according to claim 13 , which is an ink jet printer cartridge.
15. An aqueous colloidal gold solution according to claim 6 , comprising furthermore, as evaporation blocker,
(e) a polar organic compound with a vicinal dihydroxy group or an oligomer thereof.
16. Ink or printer cartridges containing the aqueous colloidal gold solution of claim 6 .
17. Ink or printer cartridges containing the aqueous colloidal gold solution of claim 11 .