Polymeric powders having a predetermined and controlled size and size distribution

• US 4,833,060 A
• Filed: 03/21/1988
• Issued: 05/23/1989
• Est. Priority Date: 03/21/1988
• Status: Expired due to Term

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Sreekumar, Chandra, Nair, Mridula, Pierce, Zona R.
• Primary Examiner(s): Michl, Paul R.
• Assistant Examiner(s): Lindeman, Jeffrey A.
• Application Number:
  US07/171,065
• Time in Patent Office: 428 Days
• Field of Search: 430/137, 523/333, 523/339
• US Class Current: 430/137.1
• CPC Class Codes: C08J 3/14 by precipitation from solutions C08J3/122 takes precedence
• CPC Class Codes: G03G 9/0804 whereby the components are brought together in a liquid dispersing medium
• CPC Class Codes: G03G 9/10 characterised by carrier particles

Abstract

Toner and/or carrier particles are prepared by dissolving a polymer in a solvent which is immiscible with water forming a suspension of small droplets of the polymer and solvent in water containing a promoter and silica particles, removing the solvent from the droplets and separating the solidified particles from the water.

Claims

1. A method of making polymeric particles having a predetermined and controlled size and size distribution which comprises dissolving a polymer in a solvent therefor to form a solution said solvent being immiscible with water, forming a suspension of small droplets of said solution in water containing a promoter and silica particles having an average prticle size of from 0.001 μ

m to 1 μ

m by high shear agitation, said promoter being a water soluble compound that affects the hydrophilic/hydrophobic balance of the silica particles in the water suspension, removing the solvent from the droplets and separating the solidified polymer particles from the water.

2. The method of claim 1 wherein the silica is removed from the surface of the resulting particles.

3. A method of making electrostatographic toner or carrier particles having a predetermined and controlled size and size distribution which comprises dissolving a polymer in a solvent therefor to form a solution said solvent being immiscible with water, forming a suspension of small droplets of said solution in water containing a promoter and silica particles having an average particle size of from 0.001 μ

m to 1 μ

m by high shear agitation, said promoter being a water soluble compound that affects the hydrophilic/hydrophobic balance of the silica particles in the water suspension, removing the solvent from the droplets and separating the solidified polymer particles from the water.

4. The method of claim 3 wherein the silica is removed from the surface of the resulting particles.

5. The method of claim 3 wherein the silica particles have an average particle size of from about 5 to about 35 nanometers.

6. The method of claim 3 wherein the concentration of silica is from 0.5 to about 21 ml. per 100 grams of polymer and solvent.

7. The method of claim 5 wherein the silica particles have an average particle size of from about 10-25 nonometers.

8. The method of claim 6 wherein the concentration of silica is from 0.5 to 10 ml per 100 grams of polymer and solvent.

9. The method of claim 3 wherein the pH during the suspension forming step is maintained at from 2 to about 7.

10. The method of claim 9 wherein the pH during the suspension forming step is maintained at from 3 to 6.

11. The method of claim 3 wherein the promoter is poly(adipic acid-co-methylaminoethanol).

12. The method of claim 3 wherein the droplets of polymer and solvent contain coloring agents.

13. The method of claim 3 wherein the droplets of polymer and solvent contain magnetic particles.

14. The method of claim 3 wherein the droplets of polymer and solvent contain charge control agents.