Ink compositions

Claim 2

An ink composition comprised of a vehicle, an acidic pigment, and associated with said pigment, N,N'-bis(aminopropyl)ethylene diamine and which ink possesses a high viscosity prior to shearing, a low viscosity during shearing, and a high viscosity after shearing and wherein said high viscosity is from about 5 to about 200 centipoise measured at a shear rate of about 25 sec -1 , said low viscosity is from about 1 to about 10 centipoise during shearing at about 150 sec -1 . and said high viscosity is from about 5 centipoise to about 200 centipoise after shearing, and wherein pH of the ink is from about 8.8 to about 9.2.

Claim 3

An ink in accordance with claim 1 wherein said high viscosity is from about 20 to about 500 centipoise, and said low viscosity is from about 1 to about 10 centipoise, said vehicle is water, said pigment is carbon black.

Claim 4

An ink in accordance with claim 2 wherein said high viscosity is from about 50 to about 300 centipoise and said low viscosity is from about 2 to about 5 centipoise.

Claim 5

An ink in accordance with claim 1 further containing ink additives.

Claim 6

An ink in accordance with claim 4 wherein said ink additives are selected from the group consisting of a humectant, a biocide, and mixtures thereof, each present in an amount of from about 1 to about 50 weight percent.

Claim 7

An ink in accordance with claim 5 wherein the humectant is a glycol.

Claim 8

An ink in accordance with claim 1 wherein the pigment is present in an amount of about 1 to about 10 percent by weight.

Claim 9

An ink in accordance with claim 2 wherein the water is present in an amount of from about 75 to about 99.5 percent by weight.

Claim 10

An ink in accordance with claim 5 wherein the humectant is a glycol selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, and mixtures thereof.

Claim 11

An ink in accordance with claim 1 further containing a biocide present in the amount of from about 0.02 to about 0.1 percent by weight.

Claim 12

An ink in accordance with claim 2 wherein said amine is present in an amount of from about 0.01 to about 50 weight percent of said carbon black.

Claim 13

An ink in accordance with claim 11 wherein said amount is from about 0.1 to about 5 weight percent.

Claim 14

An ink in accordance with claim 1 wherein said amine is present in an amount of from about 0.01 to about 50 weight percent.

Claim 15

A process which comprises providing an acoustic ink printer having a pool of ink with a free surface, and a printhead including at least one droplet ejector for radiating the free surface of said ink with focused acoustic radiation to eject individual droplets of ink therefrom on demand, said radiation being brought to focus with a finite waist diameter in a focal plane, and wherein said ink is comprised of a vehicle, an acidic pigment, and associated with said pigment N-bis(aminopropyl)ethylene diamine, and which ink possesses a high viscosity prior to shearing, a low viscosity during shearing, and a high viscosity after shearing, and wherein said high viscosity is from about 5 to about 200 centipoise measured at a shear rate of about 25 sec -1 . said low viscosity is from about 1 to about 10 centipoise during shearing at about 150 sec -1 , and said high viscosity is from about 5 centipoise to about 200 centipoise after shearing, and wherein said pH of the ink is from about 8.8 to about 9.2.

Claim 16

A process which comprises providing an acoustic ink printer having a pool of ink with a free surface, and a printhead including at least one droplet ejector for radiating the free surface of said ink with focused acoustic radiation to eject individual droplets of ink therefrom on demand, said radiation being brought to focus with a finite waist diameter in a focal plane, and wherein said ink is comprised of a vehicle, an acidic pigment, and associated with said pigment N-bis(aminopropyl)ethylene diamine, and which ink possesses a high viscosity prior to shearing, a low viscosity during shearing, and a high viscosity after shearing, and wherein said high viscosity is from about 5 to about 200 centipoise measured at a shear rate of about 25 sec -1 . said low viscosity is from about 1 to about 10 centipoise during shearing at about 150 sec -1 , and said high viscosity is from about 5 centipoise to about 200 centipoise after shearing, and wherein said pH of the ink is from about 8.8 to about 9.2.

Claim 17

An ink composition comprised of a vehicle, an acidic pigment, and associated with said pigment N-bis(aminopropyl)ethylene diamine, and which ink possesses a high viscosity prior to shearing, a low viscosity during shearing, and a high viscosity after shearing, and wherein said high viscosity is from about 5 to about 200 centipoise measured at a shear rate of about 25 sec -1 , said low viscosity is from about 1 to about 10 centipoise during shearing at about 150 sec -1 , and said high viscosity is from about 5 centipoise to about 200 centipoise after shearing, and wherein pH of the ink is from about 8.8 to about 9.2.

Claim 18

An ink composition comprised of a vehicle, an acidic pigment, and associated with said pigment N-bis(aminopropyl)ethylene diamine, and which ink possesses a high viscosity prior to shearing, a low viscosity during shearing, and a high viscosity after shearing, and wherein said high viscosity is from about 5 to about 200 centipoise measured at a shear rate of about 25 sec -1 , said low viscosity is from about 1 to about 10 centipoise during shearing at about 150 sec -1 , and said high viscosity is from about 5 centipoise to about 200 centipoise after shearing, and wherein pH of the ink is from about 8.8 to about 9.2.