Electrophotographic toner surface treated with silica mixtures

• US 6,210,851 B1
• Filed: 12/01/1999
• Issued: 04/03/2001
• Est. Priority Date: 12/01/1999
• Status: Expired due to Term

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Srinivasan, Satyanarayan A., Alexandrovich, Peter S.
• Primary Examiner(s): MARTIN, ROLAND E
• Application Number:
  US09/451,554
• Time in Patent Office: 489 Days
• Field of Search: 430/110, 430/111
• US Class Current: 430/108.2
• CPC Class Codes: G03G 9/09716 treated with organic compounds
• CPC Class Codes: G03G 9/09725 Silicon-oxides; Silicates
• CPC Class Codes: G03G 9/1133 obtained by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: G03G 9/1134 containing fluorine atoms

Abstract

An electrostatographic toner comprising toner particles that have been surface treated with a solvent and silica particles having a BET surface area of 40 to 400 m²/g; wherein the solvent is selected from aliphatic alcohols, diols and triols, aliphatic ketones, aliphatic esters, cyclic ethers and aliphatic ethers.

Claims

1. An electrostatographic toner comprising toner particles that have been surface treated with a mixture of silica particles;

one type of silica particles having a particle size of 0.05 to 30 μ

m and containing a solvent selected from aliphatic alcohols, diols, and triols, aliphatic ketones, aliphatic esters, cyclic ethers and aliphatic ethers; and

a second type of silica particles having a BET surface area of 40 to 400 m²/g.

2. The electrostatographic toner of claim 1, wherein the silica particles having a BET surface area of 40 to 400 m²/g are hydrophobic silicas.

3. The electrostatographic toner of claim 1 wherein the silica particles having a BET surface area of 40 to 400 m²/g comprise 0.1 to 5.0 weight percent of the toner, based on the weight of untreated toner.

4. The electrostatographic toner of claim 1 wherein the silica particles having a BET surface area of 40 to 400 m²/g comprise 0.1 to 2.0 weight percent of the toner, based on the weight of untreated toner.

5. The electrostatographic toner of claim 1 wherein the silica particles having a particle size of 0.05 to 30.0 μ

m comprise 0.1 to 5.0 weight percent of the toner, based on the weight of untreated toner.

6. The electrostatographic toner of claim 1 wherein the silica particles having a particle size of 0.05 to 30.0 μ

m comprise 0.5 to 3.0 weight percent of the toner, based on the weight of untreated toner.

7. An electrostatographic developer comprising the toner described in claim 1 and further comprising at least one carrier particle.

8. The electrostatographic developer as in claim 7 wherein the carrier particle is a ferrite, a magnetites, or a sponge iron.

9. The electrostatographic developer of claim 8 wherein the carrier particle is a ferrite.

10. The electrostatographic developer as in claim 7 wherein the carrier particle is coated with a polymer.

11. An electrostatographic developer as in claim 10 wherein the polymer coating of the carrier particle is a silicone resin type polymer, a poly(vinylidene fluoride), a poly(methyl methacrylate) or a mixture of poly(vinylidene fluoride) and poly(methyl methacrylate).

12. An electrostatographic toner as in claim 1 further comprising a colorant, a charge control agent, or a wax.

13. An electrostatographic toner, surface treated as in claim 1 and prepared by means of an organic solvent/aqueous chemical process.

14. An electrostatographic toner, surface treated as in claim 1 and prepared by means of a limited coalescense process.

15. An electrostatographic toner, surface treated as in claim 1 wherein the solvent is 0.1 to 5.0 weight % based on the weight of untreated toner.

19. The electrostatographic toner according to claim 1, wherein the one type of silica particles having a particle size of 0.05 to 30 μ

m is a fine inorganic particle silica and the second type of silica particles having a BET surface area of 40 to 400 m²/g is a fumed silica.

21. The electrostatographic toner of claim 1, wherein the silica particles having a BET surface area of 40 to 400 m²/g are hydrophobic silicas.

16. A method of making an electrostatographic toner comprising mixing at least one first silica particle having a BET surface area of 40 to 400 m²/g with at least one second silica particle of a particle size of 0.05 to 30 μ

m.

17. The method of claim 16 wherein either the first silica particle or the second silica particle is treated with a solvent wherein the solvent is an aliphatic alcohol, diol or triol;

aliphatic ketone, aliphatic ester, cyclic ether or aliphatic ether, or combinations thereof.

18. The method of claim 16 wherein the second silica particle is treated with a solvent.

20. The method according to claim 16, wherein the first silica particle having a BET surface area of 40 to 400 m²/g is a fumed silica and second silica particle having a particle size of 0.05 to 30 μ

m is a fine inorganic particle silica.