Process for making pigmented ink jet inks

• US 5,026,427 A
• Filed: 10/12/1988
• Issued: 06/25/1991
• Est. Priority Date: 10/12/1988
• Status: Expired due to Term

• Current Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Mitchell, Robert D., Trout, Torence J.
• Primary Examiner(s): Dixon, Jr., William R.
• Assistant Examiner(s): KLEMANSKI, HELENE G
• Application Number:
  US07/256,809
• Time in Patent Office: 986 Days
• Field of Search: 106/23, 106/20, 106/401, 366/136, 366/173, 366/176
• US Class Current: 106/31.6
• CPC Class Codes: B01F 2101/35 Mixing inks or toners
• CPC Class Codes: B01F 23/51 Methods thereof
• CPC Class Codes: B01F 23/56 by introducing solids in liquids, e.g. dispersing or dissolving
• CPC Class Codes: B01F 25/20 Jet mixers, i.e. mixers using high-speed fluid streams using jets to create vortex flow B01F25/10
• CPC Class Codes: B01F 33/821 with consecutive receptacles
• CPC Class Codes: C09D 11/322 Pigment inks

Abstract

In accordance with this invention there is provided a process for the preparation of pigmented ink jet inks comprising:

(a) mixing at least one pigment and at least one pigment dispersant in a dispersant medium to form a pigmented ink mixture wherein pigment is present in an amount up to 60% by weight based on the total weight of the mixture;

(b) deflocculating the pigmented ink mixture by passing the pigmented ink mixture through at least a plurality of nozzles within a liquid jet interaction chamber at a liquid pressure of at least 1,000 psi to produce a substantially uniform dispersion of pigment particles in the dispersant medium.

Claims

1. A process for the preparation of pigmented ink jet inks comprising:

(a) mixing at least one pigment and at least one water soluble pigment dispersant in a carrier liquid selected from the group consisting of water or a mixture of water and at least one water-soluble organic solvent to form a pigmented ink mixture wherein pigment is present in an amount from about 0.1% to about 30% by weight based on the total weight of the mixture; and

(b) deflocculating the pigmented ink mixture by passing the pigmented ink mixture through at least a plurality of nozzles within a liquid jet interaction chamber at a liquid pressure of at least 1,000 psi to produce a substantially uniform dispersion of pigment in the carrier liquid.

2. A process according to claim 1 wherein the pigmented ink is diluted with at least one liquid which is compatible with the carrier liquid to form an ink containing pigment in the range of 0.1% to 10% by weight based on the total weight of the mixture when the mixture of step (a) has pigment present in an amount exceeding 10%, said dilution being made either before or after the deflocculation of step (b).

3. A process according to claim 1 wherein the dispersant is selected from the group consisting of surfactants and polymeric pigment dispersants.

4. A process according to claim 1 wherein the the liquid jet interaction chamber comprises, in combination,

(a) a plurality of submerged nozzles providing elongated orifices arranged to eject under pressure a plurality of thin sheets of the pigmented ink jet mixture, the nozzles being arranged to effect turbulent jet action of the sheets along a common liquid jet interaction front and the sheets being ejected by the nozzles into a low pressure zone filled with the liquid futher creating turbulent jet interaction along a common boundary essentially defined and formed by the mixture in the low pressure zone and by the sheets ejected into the low pressure zone;

(b) jet interaction chamber-defining means arranged to provide the low pressure to the nozzles; and

(c) inlet channel means to deliver the mixture under pressure to the nozzles; and

(d) means to withdraw the pigmented ink mixture in the form of a dispersion from the low pressure zone.

5. A process according to claim 2 wherein the pigmented ink is diluted with the dispersant medium.

6. A process according to claim 1 wherein the mixing in step (a) is conducted in liquid jet interaction chamber at a liquid pressure of at least 1000 psi.

7. A process according to claim 6 wherein the liquid jet interaction chamber comprises, in combination,

(a) a plurality of submerged nozzles providing elongated orifices arranged to eject under pressure a plurality of thin sheets of the pigmented ink jet mixture, the nozzles being arranged to effect turbulent jet action of the sheets along a common liquid jet interaction front and the sheets being ejected by the nozzles into a low pressure zone filled with the liquid futher creating turbulent jet interaction along a common boundary essentially defined and formed by the mixture in the low pressure zone and by the sheets ejected into the low pressure zone;

(b) jet interaction chamber-defining means arranged to provide the low pressure to the nozzles; and

(c) inlet channel means to deliver the mixture under pressure to the nozzles; and

(d) means to withdraw the pigmented ink mixture in the form of a dispersion from the low pressure zone.

8. A process according to claim 1 wherein the surface tension of the ink is in the range of about 20 dyne/cm to about 70 dyne/cm.

9. A process according to claim 1 wherein the viscosity of the ink is in the range of about 1.0 cP to about 5.0 cP.

10. A process according to claim 1 wherein the ink mixture contains at least one additive selected from the group consisting of biocides, humectants, chelating agents, and viscosity modifiers.