DURABLE OUTDOOR INKJET INKS
An inkjet ink for printing durable outdoor images with an inkjet printer includes an basic pH aqueous ink vehicle comprising water, a soluble base, and at least one water soluble organic solvent; a pigment dispersion; and a polymer comprising base neutralized carboxylic acid groups with a glass transition temperature between 0 and 150° C. and an acid number between 50 and 1000 mg KOH/g dissolved in the vehicle, wherein the carboxylic acid groups are base neutralized; a poly-electrophilic functionalized compound capable of crosslinking the neutralized carboxylic acidic groups on the polymer wherein the ratio of the poly-electrophilic groups on the functionalized compound to carboxylic acid groups on the polymer is 1:1 or less on an equivalent basis and the ink maintains a stable viscosity and pigment particle size distribution for 6 weeks at 60° C.; the water in the ink inhibiting the crosslinking reaction until after the ink is printed and the water is substantially removed from the ink by drying.
1 . An inkjet ink for printing images with an inkjet printer comprising:
a basic pH aqueous ink vehicle including water, a soluble base, and at least one water soluble organic solvent;
a pigment dispersion; and
a polymer including base neutralized carboxylic acid groups with a glass transition temperature between 0° C. and 150° C. and an acid number between 50 and 1000 mg KOH/g dissolved in the vehicle, wherein the carboxylic acid groups are base neutralized;
a poly-electrophilic functionalized compound capable of crosslinking the neutralized carboxylic acidic groups on the polymer wherein the ratio of the poly-electrophilic groups on the functionalized compound to carboxylic acid groups on the polymer is 1:1 or less on an equivalent basis and the ink maintains a stable viscosity and pigment particle size distribution for 6 weeks at 60° C.;
the water in the ink inhibiting the crosslinking reaction until after the ink is printed and the water is substantially removed from the ink by drying;
the ink does not contain tertiary amines.
2 . The inkjet ink as claimed in claim 1 , wherein said polymer is a polystyrene-co-acrylate polymer resin binder.
3 . The inkjet ink as claimed in claim 1 , wherein said poly-electrophilic functionalized compound is a compound selected from the group consisting of a beta hydroxy amide crosslinker, an oxazoline functionalized reactive polymer crosslinker, a highly methylated, monomeric melamine crosslinker, an isocyanate crosslinker, an organic titinate crosslinker, an organosilane crosslinker, a glycidyl ether crosslinker, a multifunctional type aliphatic epoxy crosslinker, a polyfunctional aziridine liquid crosslinker, or a polymeric carbodiimide crosslinking agent.
4 . The inkjet ink as claimed in claim 1 , wherein at least one water soluble organic solvent is a humectant.
5 . The inkjet ink as claimed in claim 1 , further comprising a surfactant.
6 . The inkjet ink as claimed in claim 1 , further comprising a first surfactant to modify static surface tension and a second surfactant to modify dynamic surface tension.
7 . The inkjet ink as claimed in claim 1 , further comprising a biocide.
8 . The inkjet ink as claimed in claim 1 , wherein said soluble base is a non-volatile base.
9 . The inkjet ink as claimed in claim 1 , wherein the pH of said basic pH aqueous ink vehicle is between 7 and 10.
10 . The inkjet ink as claimed in claim 1 , wherein said polymer is a soluble copolymer.
11 . The inkjet ink as claimed in claim 1 , wherein said polymer is not a dispersed polymer.
12 . The inkjet ink as claimed in claim 1 , wherein said polymer is not a latex.
13 . The inkjet ink as claimed in claim 1 , wherein said poly-electrophilic functionalized compound includes at least three reactive groups.
14 . The inkjet ink as claimed in claim 1 , wherein said polymer is less than 10% of the ink by weight.
15 . The inkjet ink as claimed in claim 1 , wherein said polymer has a molecular weight less than 50,000.
16 . The inkjet ink as claimed in claim 1 , wherein said acid number is between 50 and 400.
17 . The inkjet ink as claimed in claim 1 , wherein said water soluble organic solvent is less than 50% of the ink by weight.
18 . The inkjet ink as claimed in claim 1 , wherein said water soluble organic solvent is less than 30% of the ink by weight.
19 . The inkjet ink as claimed in claim 1 , wherein an average particle size of a pigment in said pigment dispersion is less than a micron.
20 . The inkjet ink as claimed in claim 1 , wherein said pigment dispersion is less than 20% of the ink by weight.
21 . The inkjet ink as claimed in claim 1 , wherein said pigment dispersion is less than 10% of the ink by weight.
22 . The inkjet ink as claimed in claim 1 , wherein the viscosity changes less than 20% in 6 weeks at 60° C.
23 . The inkjet ink as claimed in claim 1 , wherein the pigment particle size distribution changes less than 200 nm in 6 weeks at 60° C.
24 . The inkjet ink as claimed in claim 1 , wherein the pigment particle size distribution changes less than 50 nm in 6 weeks at 60° C.
25 . The inkjet ink as claimed in claim 1 , wherein the ratio of the poly-electrophilic groups on the functionalized compound to carboxylic acid groups on the polymer is 0.5:1 or less on an equivalent basis.
26 . The inkjet in as claimed in claim 1 , wherein the inkjet ink is for printing images on non-coated surfaces.
27 . The inkjet ink as claimed in claim 1 , wherein the viscosity changes less than 10% in 6 weeks at 60° C.
28 . The inkjet ink as claimed in claim 1 , wherein said soluble base is ammonia.