Method of filtering porous particles

• US 8,241,828 B2
• Filed: 04/30/2009
• Issued: 08/14/2012
• Est. Priority Date: 04/30/2009
• Status: Active Grant

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Bennett, James R., Nair, Mridula
• Primary Examiner(s): LE, HOA VAN
• Application Number:
  US12/432,836
• Publication Number:
  US 20100279225A1
• Time in Patent Office: 1,202 Days
• Field of Search: 430/137.1, 430/137.15, 430/137.16
• US Class Current: 430/137.16
• CPC Class Codes: G03G 9/0804 whereby the components are brought together in a liquid dispersing medium
• CPC Class Codes: G03G 9/0806 whereby chemical synthesis of at least one of the toner components takes place
• CPC Class Codes: G03G 9/0815 Post-treatment
• CPC Class Codes: G03G 9/0821 characterised by physical parameters magnetic parameters G03G9/083
• CPC Class Codes: G03G 9/0823 Electric parameters
• CPC Class Codes: G03G 9/0825 characterised by their structure; characterised by non-homogenuous distribution of components microcapsular toners G03G9/093
• CPC Class Codes: G03G 9/0827 characterised by their shape, e.g. degree of sphericity

Abstract

The present invention is a method of manufacturing porous polymer particles comprising: forming a dispersion of porous polymer particles in an external aqueous phase, wherein individual porous particles each comprise a continuous polymer phase and internal pores containing an internal aqueous phase; and filtering the dispersion of porous polymer particles with a filter to remove the external aqueous phase, wherein the filtering is done while agitating the porous particles.

Claims

1. A method of manufacturing porous polymer particles comprising:

forming a dispersion of washed porous polymer particles in an external aqueous phase, wherein individual porous particles each comprise a continuous polymer phase and internal pores containing an internal aqueous phase comprising a pore stabilizing hydrocolloid, the external aqueous phase of the dispersion of porous polymer particles has a specific conductivity of less than 100 microSeimens/cm and the ionic strength in the external aqueous phase is lower than the ionic strength in the internal aqueous phase, and the porous polymer particles have a porosity of greater than 10% based on volume of the internal pores as a percentage of the total volume of the particles; and

filtering the dispersion of washed porous polymer particles with a filter to remove the external aqueous phase and isolate the porous polymer particles, wherein the filtering is done while agitating the porous particles.

2. The method of claim 1, wherein greater than atmospheric pressure is applied to the dispersion of porous polymer particles during filtration.

3. The method of claim 1, wherein lower than atmospheric pressure is applied on a side of the filter opposite to the dispersion of porous polymer particles during filtration.

4. The method of claim 1, wherein the external aqueous phase of the dispersion of porous polymer particles has a specific conductivity of less than 10 microSeimens/cm.

5. The method of claim 1, wherein the external aqueous phase of the dispersion of porous polymer particles has a specific conductivity of less than 3 microSeimens/cm.

6. The method of claim 1 further comprising drying the filtered porous polymer particles to remove the internal aqueous phase from the internal pores.

7. The method of claim 1, wherein the polymer comprises a polymer formed from vinyl monomers, condensation monomers, condensation esters, or mixtures thereof.

8. The method of claim 1, wherein the polymer is selected from the group consisting of polyesters, styrenes, vinyl ethers, and vinyl ketones.

9. The method of claim 1, wherein the polymer comprises a polyester.

10. A method according to claim 1, wherein the dispersion of porous polymer particles in an external aqueous phase is formed by the steps comprising:

providing a first emulsion of a first aqueous phase comprising a pore stabilizing hydrocolloid dispersed in an organic solution containing a polymer;

dispersing the first emulsion in a second aqueous phase to form a second emulsion;

shearing the second emulsion in the presence of a stabilizing agent to form droplets of the first emulsion in the second aqueous phase; and

evaporating the organic solution from the droplets to form the aqueous dispersion of porous polymer particles.

11. The method of claim 10, wherein the hydrocolloid is selected from the group consisting of carboxymethyl cellulose (CMC), gelatin, alkali-treated gelatin, acid treated gelatin, gelatin derivatives, proteins, protein derivatives, synthetic polymeric binders, water soluble microgels, polystyrene sulphonate, poly(2-acrylamido-2-methylpropanesulfonate), and polyphosphates.

12. The method of claim 10, wherein the first aqueous phase further comprises buffering salts.

13. The method of claim 10, wherein the stabilizing agent comprises poylvinylpyrrolidone, polyvinylalchol, colloidal silica, or latex particles.

14. The method of claim 10, wherein the organic solution comprises ethyl acetate, propyl acetate, chloromethane, dichloromethane, vinyl chloride, trichloromethane, carbon tetrachloride, ethylene chloride, trichloroethane, toluene, xylene, cyclohexanone, or 2-nitropropane.

15. The method of claim 10, wherein the porous polymer particles comprise toner particles.

16. The method of claim 15, wherein the first emulsion further comprises a colorant.

17. The method of claim 15, wherein the first emulsion further comprises a colorant, a wax, and a charge control agent.

18. The method according to claim 1, wherein the dispersion of porous polymer particles in an external aqueous phase is formed by the steps comprising:

providing a first emulsion of a first aqueous phase comprising a pore stabilizing hydrocolloid dispersed in an organic solution containing water-immiscible polymerizable monomers and a polymerization initiator;

dispersing the first emulsion in a second aqueous phase to form a second emulsion;

shearing the second emulsion in the presence of a stabilizing agent to form droplets of the first emulsion in the second aqueous phase;

polymerizing the monomers to form droplets of polymer particles; and

evaporating the organic solution from the droplets of polymer particles to form an aqueous dispersion of porous polymer particles.

19. The method according to claim 1, wherein the dispersion of porous polymer particles in an external aqueous phase is formed by the steps comprising:

providing a first emulsion of a first aqueous phase comprising a pore stabilizing hydrocolloid dispersed in a mixture of water-immiscible polymerizable monomers and a polymerization initiator;

dispersing the first emulsion in a second aqueous phase to form a second emulsion;

shearing the second emulsion in the presence of a stabilizing agent to form droplets of the first emulsion in the second aqueous phase; and

polymerizing the monomers to form droplets of polymer particles to form an aqueous dispersion of porous polymer particles.