Control of particle growth with complexing agents
View Patent ↗A method of making particles suitable for use as toners includes forming a mixture of sulfonated polyester resin, a colorant dispersion and optionally a wax dispersion, homogenizing the mixture, adding a coagulant to the mixture to aggregate the mixture to form aggregated particles, and coalescing the aggregated particles to form coalesced particles. In the method, when a predetermined average particle size is achieved during the aggregation and/or coalescing step, a complexing agent that complexes with ions of the coagulant is added in an amount effective to substantially halt any further particle growth. The complexing agent is believed to halt further growth by complexing with free coagulant ions still in the solution.
1. A method, comprising:
forming a mixture of sulfonated polyester resin, a colorant dispersion and optionally a wax dispersion,
homogenizing the mixture,
adding a coagulant to the mixture and aggregating the mixture to form aggregated particles, and
coalescing the aggregated particles to form coalesced particles,
wherein when a predetermined average particle size is achieved during the aggregation and/or coalescing step, a complexing agent that complexes with ions of the coagulant is added in an amount effective to substantially halt any further particle growth.
2. The method according to claim 1 , wherein the sulfonated polyester resin is an alkali metal sulfonated polyester resin.
3. The method according to claim 1 , wherein the sulfonated polyester resin is a mixture of two or more sulfonated polyester resins.
4. The method according to claim 1 , wherein the sulfonated polyester resin is comprised of both amorphous sulfonated polyester resin and crystalline sulfonated polyester resin.
5. The method according to claim 4 , wherein the amorphous sulfonated polyester resin is branched.
6. The method according to claim 1 , wherein the sulfonated polyester is selected from the group consisting of copoly(ethylene-terephthalate)-copoly-(ethylene-5-sulfo-isophthalate), copoly(propylene-terephthalate)-copoly(propylene-5-sulfo-isophthalate), copoly(diethylene-terephthalate)-copoly(diethylene-5-sulfo-isophthalate), copoly(propylene-diethylene-terephthalate)-copoly(propylene-diethylene-5-sulfo-isophthalate), copoly(propylene-butylene-terephthalate)-copoly(propylene-butylene-5-sulfo-isophthalate), copoly(propoxylated bisphenol-A-fumarate)-copoly(propoxylated bisphenol A-5-sulfo-isophthalate), copoly(ethoxylated bisphenol-A-fumarate)-copoly(ethoxylated bisphenol-A-5-sulfo-isophthalate), and copoly(ethoxylated bisphenol-A-maleate)-copoly(ethoxylated bisphenol-A-5-sulfo-isophthalate), and wherein the alkali metal is, for example, a sodium, lithium or potassium ion. Examples of crystalline alkali sulfonated polyester based resins alkali copoly(5-sulfoisophthaloyl)-co-poly(ethylene-adipate), alkali copoly(5-sulfoisophthaloyl)-copoly(propylene-adipate), alkali copoly(5-sulfoisophthaloyl)-copoly(butylene-adipate), alkali copoly(5-sulfo-isophthaloyl)-copoly(pentylene-adipate), and alkali copoly(5-sulfo-iosphthaloyl)-copoly(octylene-adipate), alkali copoly(5-sulfo-isophthaloyl)-copoly(ethylene-adipate), alkali copoly(5-sulfo-isophthaloyl)-copoly(propylene-adipate), alkali copoly(5-sulfo-isophthaloyl)-co-poly(butylene-adipate), alkali copoly(5-sulfo-isophthaloyl)-copoly(pentylene-adipate), alkali copoly(5-sulfo-isophthaloyl)-copoly(hexylene-adipate), alkali copoly(5-sulfo-isophthaloyl)-copoly(octylene-adipate), alkali copoly(5-sulfoisophthaloyl)-copoly(ethylene-succinate), alkali copoly(5-sulfoisophthaloyl-copoly(butylene-succinate), alkali copoly(5-sulfoisophthaloyl)-copoly(hexylene-succinate), alkali copoly(5-sulfoisophthaloyl)-copoly(octylene-succinate), alkali copoly(5-sulfo-isophthaloyl)-copoly(ethylene-sebacate), alkali copoly(5-sulfo-isophthaloyl)-copoly(propylene-sebacate), alkali copoly(5-sulfo-isophthaloyl)-copoly(butylene-sebacate), alkali copoly(5-sulfo-isophthaloyl)-copoly(pentylene-sebacate), alkali copoly(5-sulfo-isophthaloyl)-copoly(hexylene-sebacate), alkali copoly(5-sulfo-isophthaloyl)-copoly(octylene-sebacate), alkali copoly(5-sulfo-isophthaloyl)-copoly(ethylene-adipate), alkali copoly(5-sulfo-isophthaloyl)-copoly(propylene-adipate), alkali copoly(5-sulfo-iosphthaloyl)-copoly(butylene-adipate), alkali copoly(5-sulfo-isophthaloyl)-copoly(pentylene-adipate), and alkali copoly(5-sulfo-isophthaloyl)copoly(hexylene-adipate), poly(octylene-adipate), and wherein the alkali is a metal of sodium, lithium or potassium.
7. The method according to claim 1 , wherein the coagulant comprises a metal salt.
8. The method according to claim 1 , wherein the coagulant comprises zinc acetate.
9. The method according to claim 1 , wherein the complexing agent is selected from the group consisting of ethylenediamine tetraacetic acid, ethylene diamine disuccininc acid, nitrilotriacetate, methylglycinediacetic acid, glutamate-N,N-bis(carboxymethyl), carboxymethylchitosan (under biscarboxymethyl umbrella), dimercaptosuccinic acid (DMSA), diethylenetriaminepentaacetate (DTPA) and mixtures thereof.
10. The method according to claim 1 , wherein the complexing agent is dissolved in a solution including about 0.5 to about 1.0 M of a base prior to addition.
11. The method according to claim 10 , wherein the base comprises sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium carbonate, sodium bicarbonate or mixtures thereof.
12. The method according to claim 1 , wherein the complexing agent is dissolved in a solution including a base prior to addition, and wherein the base is present in the solution in an amount of from about 0.5 to about 10 weight percent relative to the weight of the complexing agent in the solution.
13. The method according to claim 12 , wherein the base comprises sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium carbonate, sodium bicarbonate or mixtures thereof.
14. The method according to claim 1 , wherein the predetermined average particle size is from about 3 to about 15 micrometers.
15. The method according to claim 1 , wherein the particles obtained have an average particle size of about 3 to about 15 micrometers and a geometric size distribution of about 1.05 to about 1.35.
16. The method according to claim 1 , wherein the coagulant is added in an amount of from about 0.5 to about 5% by weight of the resin.
17. The method according to claim 16 , wherein the complexing agent is added in an amount of from about 0.01 to about 8% by weight of solids in the mixture.
18. A method comprising:
forming a mixture of an alkali metal sulfonated polyester resin, a colorant dispersion and optionally a wax dispersion,
homogenizing the mixture,
adding a zinc-containing coagulant to the mixture and aggregating the mixture to form aggregated particles, and
coalescing the aggregated particles to form coalesced particles,
wherein when a predetermined average particle size is achieved during the aggregation and/or coalescing step, adding a complexing agent that complexes with zinc ions of the zinc-containing coagulant in an amount effective to substantially halt any further particle growth.
19. The method according to claim 18 , wherein the alkali metal sulfonated polyester resin is a mixture of two or more alkali metal sulfonated polyester resins.
20. A method comprising:
forming a mixture of hydrophobic polyester resin emulsion, a colorant dispersion and optionally a wax dispersion,
homogenizing the mixture,
adding a zinc-containing coagulant to the mixture and aggregating the mixture to form aggregated particles, and
coalescing the aggregated particles to form coalesced particles,
wherein when a predetermined average particle size is achieved during the aggregation and/or coalescing step, ethylenediamine tetraacetic acid is added in an amount effective to substantially halt any further particle growth.
21. The method according to claim 20 , wherein the hydrophobic polyester resin has a bimodal molecular weight distribution.