Electrophotographic developing agent

• US 20060063085A1
• Filed: 06/07/2005
• Published: 03/23/2006
• Est. Priority Date: 09/23/2004
• Status: Abandoned Application

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Choi, Seok-hoon, Kim, Sang-deok, Lee, Duck-hee
• Application Number:
  US11/145,952
• Publication Number:
  US 20060063085A1
• Time in Patent Office: Days
• US Class Current: 430/108.220
• CPC Class Codes: G03G 9/0819 characterised by the dimensions of the particles
• CPC Class Codes: G03G 9/08711 with esters of acrylic or methacrylic acid
• CPC Class Codes: G03G 9/08751 Aminoplasts
• CPC Class Codes: G03G 9/08768 Other polymers having nitrogen in the main chain, with or without oxygen or carbon only
• CPC Class Codes: G03G 9/08797 characterised by their physical properties, e.g. viscosity, solubility, melting temperature, softening temperature, glass transition temperature
• CPC Class Codes: G03G 9/09708 Inorganic compounds
• CPC Class Codes: G03G 9/09716 treated with organic compounds
• CPC Class Codes: G03G 9/09725 Silicon-oxides; Silicates

Abstract

An electrophotographic developing agent is provided. The electrophotographic developing agent includes toner particles and an external additive. The toner particles include a binder resin, a colorant, and a charge control agent. The external additives which are added to the toner particles include a large-diameter silica having a primary average particle size of about 20 to about 200 nm, a small-diameter silica having a primary average particle size of about 5 to about 20 nm, a hydrophobic titanium oxide, and a polymer bead. The electrophotographic developing agent can maintain a stable charge and charge distribution of the toner over a long period due to the addition of the external additives. The external additives prevent the fogging and the image contamination in a cycle of a charging roller.

Claims

1. An electrophotographic developing agent comprising:

toner particles comprising a binder resin, a colorant, and a charge control agent; and

external additives which are added to the toner particles,

wherein the external additives comprise a large-diameter silica having a primary average particle size of about 20 to about 200 nm, a small-diameter silica having a primary average particle size of about 5 to about 20 nm, a hydrophobic titanium oxide, and a polymer bead.

2. The electrophotographic developing agent of claim 1, wherein amounts of the large-diameter silica and the small-diameter silica are respectively in a range of about 0.1 to about 3.0 parts by weight, based on 100 parts by weight of the toner particles.

3. The electrophotographic developing agent of claim 1, wherein the hydrophobic titanium oxide has an average particle size of about 10 to about 500 nm.

4. The electrophotographic developing agent of claim 3, wherein the hydrophobic titanium oxide has an average particle size of about 10 to about 100 nm.

5. The electrophotographic developing agent of claim 3, wherein the amount of the hydrophobic titanium oxide is in a range of about 0.1 to about 2.0 parts by weight, based on 100 parts by weight of the toner particles.

6. The electrophotographic developing agent of claim 1, wherein the polymer bead has an average particle size of about 0.1 to about 3 μ

m.

7. The electrophotographic developing agent of claim 6, wherein the amount of the polymer bead is in a range of about 0.1 to about 2.0 parts by weight, based on 100 parts by weight of the toner particles.

8. The electrophotographic developing agent of claim 1, wherein the polymer bead is a melamine-based bead or polymethylmethacrylate (PMMA)-based bead.

9. The electrophotographic developing agent of claim 1, wherein the polymer bead is a melamine-based bead.

10. The electrophotographic developing agent of claim 1, wherein said electrophotographic developing agent is produced by admixing the toner particles with the external additives to form a homogeneous mixture.

11. The electrophotographic developing agent of claim 1, wherein said external additives are uniformly dispersed with the toner particles and wherein said external additives adhere to an external surface of the toner particles.

12. An electrophotographic image forming apparatus using the electrophotographic developing agent of claim 1.