LOW MELT TONERS AND PROCESSES THEREOF

• US 20100021841A1
• Filed: 10/06/2009
• Published: 01/28/2010
• Est. Priority Date: 09/23/2004
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Sacripante, Guerino G., Chen, Allan K., Zwartz, Edward G., Nosella, Kimberly D., Farrugia, Valerie M., Patel, Raj D., Mayer, Fatima M., Ng, T. Hwee, Maric, Milan
• Granted Patent: US 7,781,138 B2
• Time in Patent Office: Days
• US Class Current: 430/137.140
• CPC Class Codes: G03G 9/0804 whereby the components are brought together in a liquid dispersing medium
• CPC Class Codes: G03G 9/0819 characterised by the dimensions of the particles
• CPC Class Codes: G03G 9/0821 characterised by physical parameters magnetic parameters G03G9/083
• CPC Class Codes: G03G 9/08755 Polyesters
• CPC Class Codes: G03G 9/08791 characterised by the presence of specified groups or side chains
• CPC Class Codes: G03G 9/08793 Crosslinked polymers
• CPC Class Codes: G03G 9/08795 characterised by their chemical properties, e.g. acidity, molecular weight, sensitivity to reactants
• CPC Class Codes: G03G 9/08797 characterised by their physical properties, e.g. viscosity, solubility, melting temperature, softening temperature, glass transition temperature

Abstract

A process for preparing toner particles and compositions adapted for use in preparing toners that comprise a blend of a first polyester resin with a second sharp melting polyester resin. The process includes forming an emulsion resin comprising a branched polyester resin, a crystalline polyester resin, a colorant, and optionally a wax. The resin mixture is aggregated using an aggregating agent, such as a zinc acetate solution, to form an aggregate mixture. The aggregate mixture is then coalesced at a temperature of from about 5 to about 20° C. above the T_g of the emulsion resin to produce the resultant toner particles.

Claims

1. A method for forming low melt polyester based toner, the method comprising:

forming an emulsion resin comprising a branched amorphous polyester resin component and a crystalline polyester resin component;

forming a pre-toner mixture by adding a colorant and optionally a wax to the emulsion resin;

homogenizing the pre-toner mixture;

aggregating the pre-toner mixture by adding an aggregating agent, thereby forming an aggregate mixture comprising a plurality of aggregate toner particles;

adjusting the pH of the aggregate mixture to between about 5 and about 7;

coalescing the aggregate mixture by heating the aggregate mixture to a temperature from about 5 to about 20°

C. above the glass transition temperature of the branched amorphous polyester resin component, thereby generating a mixture of coalesced toner particles; and

cooling the toner particles to room temperature.

2. The method according to claim 1, wherein each of the branched amorphous polyester resin component and the crystalline polyester resin component are an alkali sulfonated polyester resin comprising an alkali metal independently selected from the group consisting of lithium, sodium, potassium, and combinations thereof.

3. The method according to claim 2, wherein the alkali metal is lithium.

4. The method according to claim 1, wherein homogenization is maintained during the addition of the aggregating agent to the pre-toner mixture.

5. The method according to claim 1, wherein the aggregating agent comprises an aqueous solution of a metal salt selected from the group consisting of zinc acetate, zinc acetate dehydrate, zinc chloride, zinc bromide, magnesium acetate, magnesium bromide, aluminum chloride, poly-aluminum chloride, calcium chloride, calcium acetate, copper chloride, copper sulfate, and mixtures thereof.

6. The method according to claim 1, further comprising adjusting the pH of the pre-toner mixture to between about 4 to about 5 prior to homogenizing the pre-toner mixture.

13. The method according to claim 6 wherein the pH of the pre-toner mixture is adjusted using an acid or a base.

14. The method according to claim 1 wherein the pH of the aggregate mixture is adjusted by adding a base selected from the group consisting of sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium bicarbonate, and mixtures thereof.

15. The method according to claim 1 wherein the crystalline polyester resin is present in an amount of from about 5 to about 30 percent by weight of the toner compartments.

16. The method according to claim 1 wherein the crystalline polyester resin has a melting point of from about 30°

C. to about 120°

C.

17. The method according to claim 1 wherein the crystalline polyester resin has a number average molecular weight of from about 1,000 to about 50,000.

18. The method according to claim 1 wherein the crystalline polyester resin has a weight average molecular weight of from about 2,000 to about 100,000.

19. The method according to claim 1 wherein the molecular weight distribution of the crystalline polyester resin is from about 2 to about 6.

20. The method according to claim 1 wherein the branched amorphous polyester resin has an onset glass transition temperature of from about 55°

C. to about 70°

C.

7. A method for forming a low melt toner, the method comprising:

forming a pre-toner mixture comprising (i) an emulsion resin comprising an amorphous alkali sulfonated polyester resin and a crystalline alkali sulfonated polyester resin, (ii) a colorant, and (iii) optionally a wax;

adjusting the pH of the pre-toner mixture to between about 4 to about 5;

homogenizing the pre-toner mixture;

forming an aggregate mixture of aggregate toner particle by adding an aggregating agent over a period of about 10 to about 60 minutes;

adjusting the pH of the aggregate mixture to between about 5 and about 7;

heating the aggregate mixture to a temperature of from about 50 to about 80°

C. thereby forming a mixture coalesced toner particles;

controlling toner particle size by adjusting the pH of the mixture of coalesced toner particles to between about 5 and about 7; and

cooling the mixture of coalesced toner particles to room temperature.

8. The method according to claim 7, wherein the alkali is an alkali metal independently selected from the group consisting of lithium, sodium, potassium and combinations thereof.

9. The method according to claim 7, wherein the alkali is lithium.

10. The method according to claim 7 wherein the pH of the pre-toner mixture is adjusted using an acid or a base.

11. The method according to claim 7 wherein the pH of the aggregate mixture is adjusted by adding a base selected from the group consisting of sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium bicarbonate, and mixtures thereof.

12. The method according to claim 7 wherein homogenization is maintained during the addition of the aggregating agent to the pre-toner mixture.