Continuous coalescence processes

Patent metadata

Field	Value
Publication number	US-2017192370-A1
Application number	US-201715464535-A
Country	US
Kind code	A1
Filing date	Mar 21, 2017
Priority date	Apr 4, 2013
Publication date	Jul 6, 2017
Grant date	—

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

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

2 . The continuous system of claim 1 , wherein the pumping apparatus is a positive displacement pump.

3 . The continuous system of claim 1 , wherein the first, second and third zones of the extruder each include an associated thermocouple for monitoring and controlling the temperature of its associated zone.

4 . The continuous system of claim 1 , wherein the extruder includes an elongated screw defining an elongated axis, and wherein the screw, rotatably mounted within the extruder, is rotatable about the axis.

5 . The continuous system of claim 4 , wherein the elongated screw comprises a first screw element disposed in the first zone, a second screw element disposed in the second zone, and a third screw element disposed in the third zone, wherein the first, second and third screw elements are disposed along the axis.

6 . The continuous system of claim 4 , where the screw is rotated 50 rpm to about 1000 rpm about the axis.

7 . The continuous system of claim 4 , where the screw is rotated 250 rpm to about 750 rpm about the axis.

8 . The continuous system of claim 4 , wherein the screw is a two-lobe screw.

9 . The continuous system of claim 1 , wherein each zone has a pH meter for monitoring the pH of the zone.

10 . The continuous system of claim 1 , wherein:
the residence time in the first zone is from about 0.15 minutes to about 1 minute; the residence time in the second zone is from about 0.15 minutes to about 1 minute; the residence time in the third zone is from about 0.15 minutes to about 1 minute; and the residence time within the multi-zone extruder is from about 0.5 minutes to about 2 minutes.

11 . The continuous system of claim 1 , wherein the feeding apparatus comprises a supply port for pumping the slurry at a pressure of from about 5.0 psi to about 100 psi.

12 . The continuous system of claim 8 , wherein the screw is connected to a drive motor.

13 . The continuous system of claim 12 , wherein the multi-zone extruder comprises conveying elements.

14 . The continuous system of claim 12 wherein each conveying element has a length of from about 1350 mm to about 3000 mm.

15 . The continuous system of claim 12 , wherein each conveying element has a length of from about 1500 mm to about 2500 mm.

16 . The continuous system of claim 12 , wherein the multi-zone extruder comprises kneading elements.

17 . The continuous system of claim 16 , wherein the kneading elements have a helix angle of from about 45° to about 90°.

18 . The continuous system of claim 16 , wherein the kneading elements are forward kneading elements.

19 . The continuous system of claim 16 , wherein the kneading elements are neutral kneading elements.

20 . The continuous system of claim 16 , wherein the kneading elements are reverse kneading elements.

Assignees

• Xerox Corp

Inventors

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

Classifications

• B01F2215/0422

  Numerical values of angles · CPC title

• B01F3/1221

  Operations & Transport · mapped topic

• B01F2215/0427

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

• B01F3/20

  Operations & Transport · mapped topic

• B01F7/087

  Operations & Transport · mapped topic