Continuous coalescence processes

Patent metadata

Field	Value
Publication number	US-9639013-B2
Application number	US-201313856496-A
Country	US
Kind code	B2
Filing date	Apr 4, 2013
Priority date	Apr 4, 2013
Publication date	May 2, 2017
Grant date	May 2, 2017

Abstract

Processes for continuously coalescing particles from an aggregated particle slurry are disclosed. The aggregated particle slurry is heated, then coalesced by raising the pH. The coalesced particles are homogenized and exit as a coalesced particle slurry. A multi-screw extruder is used for the coalescing. These processes are useful for providing coalesced particles such as toner compositions.

First claim

The invention claimed is:

1. A continuous process for coalescing particles, comprising:
feeding an aggregated particle slurry into a multi-screw extruder for a predetermined residence time;
heating the aggregated particle slurry to a temperature of about 70° C. to about 98° C. in a first zone of the extruder;
adding a caustic solution to raise the pH of the aggregated particle slurry and form a coalesced particle slurry in a second zone of the extruder downstream of the first zone;
homogenizing the particles in the coalesced particle slurry in a third zone of the extruder downstream of the second zone;
measuring circularity of the particles in the coalesced particle slurry and changing the residence time within the extruder until the circularity of the particles in the coalesced particle slurry are of a predetermined value; and
pumping the coalesced particle slurry of the predetermined particle circularity from an outlet port of the multi-screw extruder.

2. The process of claim 1 , wherein the aggregated particle slurry is fed into the extruder using a positive displacement pump.

3. The process of claim 1 , wherein the aggregated particle slurry has a starting pH of about 3.0 to about 4.5.

4. The process of claim 1 , wherein the pH of the aggregated particle slurry is raised to a pH range of about 3.0 to about 7.9 in the second zone to coalesce the particles.

5. The process of claim 1 , wherein the pH of the aggregated particle slurry is raised to a pH range of about 7.0 to about 7.9 in the second zone to coalesce the particles.

6. The process of claim 1 , wherein screws in the extruder rotate at a speed of about 50 rpm to about 1000 rpm.

7. The process of claim 1 , wherein the caustic solution comprises a base selected from the group consisting of ammonium hydroxide, potassium hydroxide, sodium hydroxide, sodium carbonate, sodium bicarbonate, lithium hydroxide, potassium carbonate, triethyl amine, triethanolamine, pyridine and its derivatives, diphenylamine and its derivatives, poly(ethylene amine) and its derivatives, and combinations thereof.

8. The process of claim 1 , wherein the aggregated particle slurry is fed into the first zone of the extruder.

9. The process of claim 1 , wherein the multi-screw extruder is a twin-screw extruder.

Assignees

• Xerox Corp

Inventors

• Chung Joo T
• Cheng Chieh-Min
• Malachowski Steven M
• Young Eric Joseph
• Godshall Eric David
• Marion Brian Joseph

Classifications

• G03G9/081 Primary

  by mixing the toner components in a liquefied state; melt kneading; reactive mixing · CPC title

• G03G9/08

  with toner particles · CPC title

• B01F2215/0427

  Numerical distance values, e.g. separation, position · CPC title

• B01F27/725

  with two or more helices in respective separate casings, e.g. one casing inside the other · CPC title

• B01F2215/0477

  Numerical time values · CPC title