CARRIER, TWO-COMPONENT DEVELOPER CONTAINING CARRIER AND TONER, AND IMAGE FORMING METHOD

• US 20090202935A1
• Filed: 02/05/2009
• Published: 08/13/2009
• Est. Priority Date: 02/13/2008
• Status: Abandoned Application

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Sakashita, Shingo, Kotsugai, Akihiro, Inoue, Ryota, Moriya, Yoshihiro, Taniguchi, Keishi
• Application Number:
  US12/366,285
• Publication Number:
  US 20090202935A1
• Time in Patent Office: Days
• US Class Current: 430/109.400
• CPC Class Codes: G03G 9/0804 whereby the components are brought together in a liquid dispersing medium
• CPC Class Codes: G03G 9/0815 Post-treatment
• CPC Class Codes: G03G 9/0817 Separation; Classifying
• CPC Class Codes: G03G 9/08755 Polyesters
• CPC Class Codes: G03G 9/08782 Waxes
• CPC Class Codes: G03G 9/10 characterised by carrier particles
• CPC Class Codes: G03G 9/1075 Structural characteristics of the carrier particles, e.g. shape or crystallographic structure
• CPC Class Codes: G03G 9/1133 obtained by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: G03G 9/1135 obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: G03G 9/1136 containing silicon atoms
• CPC Class Codes: G03G 9/1137 being crosslinked
• CPC Class Codes: G03G 9/1139 Inorganic components of coatings

Abstract

A carrier including magnetic core particles and a coating layer, wherein the coating layer is formed by applying a coating liquid containing at least colloidal silica, a condensate of alkoxysilane represented by General Formula (1) and a solvent onto the core particles; an amount of colloidal silica contained in the coating layer is less than 60% by mass; and a ratio (h/Dw) of a thickness (h) of the coating layer to a weight average particle diameter (Dw) of the carrier is more than 0.01, wherein the carrier is used in a two-component developer together with a toner produced through aqueous granulation and containing at least a colorant, a binder resin and a releasing agent, and wherein an amount of the releasing agent present in a region from a surface of the toner to a depth of 0.3 μm is less than 4% by mass as measured through FTIR-ATR spectroscopy.

Claims

1. A carrier comprising:

core particles composed of a magnetic material, and

a coating layer formed on surfaces of the core particles,

wherein the coating layer is formed by applying a coating liquid containing at least colloidal silica, a condensate of alkoxysilane represented by the following General Formula (1) and a solvent onto the surfaces of the core particles;

an amount of colloidal silica contained in the coating layer is less than 60% by mass; and

a ratio (h/Dw) of a thickness (h) of the coating layer to a weight average particle diameter (Dw) of the carrier is more than 0.01,

wherein the carrier is used in a two-component developer together with a toner which is produced through aqueous granulation and contains at least a colorant, a binder resin and a releasing agent, and

wherein an amount of the releasing agent present in a region from a surface of the toner to a depth of 0.3 μ

m is less than 4% by mass as measured through Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy,

Si(R¹)_a(R²)_4-a  

 

General Formula (1)

wherein R¹ represents an alkyl group having 1 to 10 carbon atoms;

R² represents an alkoxy group having 1 to 10 carbon atoms, alkenyloxy group having 1 to 10 carbon atoms, acyloxy group having 1 to 10 carbon atoms or alkoxyalkoxy group having 1 to 10 carbon atoms; and

a is an integer of 0, 1 or 2.

2. The carrier according to claim 1, wherein the amount of colloidal silica contained in the coating layer is 0.5% by mass to 50% by mass.

3. The carrier according to claim 1, wherein the coating liquid further contains an amino resin, an acrylic resin capable of reacting with the amino resin, and microparticles.

4. The carrier according to claim 3, wherein an amount of the acrylic resin contained in the coating layer is 0.5% by mass to 30% by mass.

5. The carrier according to claim 3, wherein an amount of the microparticles contained in the coating layer is 1% by mass to 60% by mass.

6. The carrier according to claim 3, wherein the microparticles are microparticles whose surfaces have been treated with an aminosilane coupling agent.

7. The carrier according to claim 3, wherein the microparticles are conductive microparticles whose surfaces have been treated so as to have conductivity.

8. The carrier according to claim 3, wherein the coating liquid contains at least two types of microparticle.

9. The carrier according to claim 1, wherein the h/Dw satifies the relation 0.025<

h/Dw<

0.2.

10. The carrier according to claim 1, having a weight average particle diameter Dw of 20 μ

m to 65 μ

m.

11. The carrier according to claim 1, wherein the condensate of alkoxysilane represented by General Formula (1) has a molecular weight of 1,000 or lower.

12. The carrier according to claim 1, wherein the coating layer is formed by applying onto surfaces of the core particles a coating liquid which contains an aminosilane coupling agent in addition to the colloidal silica, the condensate and the solvent.

13. The carrier according to claim 1, wherein the carrier has a volume resistivity R of 10 Log (Ω

·

cm) to 16 Log (Ω

·

cm) as calculated based on a resistivity r, using the following Equation (1), the resistivity r being measured when the carrier is charged into a cell having electrodes 1 and 2 which are disposed 0.2 cm apart and which each have a surface area of 2.5 cm×

4 cm under application of a DC voltage of 1,000V between the electrodes 1 and 2.

R=Log [r×

(2.5 cm×

4 cm)÷

0.2 cm] 

 

Equation (1)

14. A two-component developer comprising:

a carrier which comprises core particles composed of a magnetic material and a coating layer formed on surfaces of the core particles,

a toner which is produced through aqueous granulation and contains at least a colorant, a binder resin and a releasing agent,

wherein the coating layer is formed by applying a coating liquid containing at least colloidal silica, a condensate of alkoxysilane represented by the following General Formula (1) and a solvent onto the surfaces of the core particles;

an amount of colloidal silica contained in the coating layer is less than 60% by mass; and

a ratio (h/Dw) of a thickness (h) of the coating layer to a weight average particle diameter (Dw) of the carrier is more than 0.01, and

wherein an amount of the releasing agent present in a region from a surface of the toner to a depth of 0.3 μ

m is less than 4% by mass as measured through Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy,

Si(R¹)_a(R²)_4-a  

 

General Formula (1)

wherein R¹ represents an alkyl group having 1 to 10 carbon atoms;

R² represents an alkoxy group having 1 to 10 carbon atoms, alkenyloxy group having 1 to 10 carbon atoms, acyloxy group having 1 to 10 carbon atoms or alkoxyalkoxy group having 1 to 10 carbon atoms; and

a is an integer of 0, 1 or 2.

15. The two-component developer according to claim 14, wherein the binder resin contained in the toner is a polyester resin.

16. The two-component developer according to claim 14, wherein the binder resin contains a modified polyester having a substituent whose end can react with an active hydrogen-containing group.

17. The two-component developer according to claim 14, wherein the releasing agent is a wax;

an amount of the wax contained in the toner is 1% by mass to 20% by mass as calculated based on a corresponding mass of an amount of heat absorbed by the wax measured through differential scanning calorimetry (DSC); and

an amount of the wax present in a region from a surface of the toner to a depth of 0.3 μ

m is 0.1% by mass or more and less than 4% by mass as measured through Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy.

18. The two-component developer according to claim 14, wherein the toner has a volume average particle diameter of 3 μ

m to 8 μ

m.

19. The two-component developer according to claim 14, wherein the toner has a ratio of a volume average particle diameter to a number average particle diameter (volume average particle diameter/number average particle diameter) of 1.00 to 1.25.

20. An image forming method comprising:

forming a latent electrostatic image on a latent electrostatic image bearing member,

developing the latent electrostatic image with use of a two-component developer to form a visible image,

transferring the visible image onto a recording medium, and

fixing the transferred image on the recording medium,

wherein the two-component developer comprises

a carrier which comprises core particles composed of a magnetic material and a coating layer formed on surfaces of the core particles,

a toner which is produced through aqueous granulation and contains at least a colorant, a binder resin and a releasing agent,

wherein the coating layer is formed by applying a coating liquid containing at least colloidal silica, a condensate of alkoxysilane represented by the following General Formula (1) and a solvent onto the surfaces of the core particles;

an amount of colloidal silica contained in the coating layer is less than 60% by mass; and

a ratio (h/Dw) of a thickness (h) of the coating layer to a weight average particle diameter (Dw) of the carrier is more than 0.01, and

wherein an amount of the releasing agent present in a region from a surface of the toner to a depth of 0.3 μ

m is less than 4% by mass as measured through Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy,

Si(R¹)_a(R²)_4-a  

 

General Formula (1)

wherein R¹ represents an alkyl group having 1 to 10 carbon atoms;

R² represents an alkoxy group having 1 to 10 carbon atoms, alkenyloxy group having 1 to 10 carbon atoms, acyloxy group having 1 to 10 carbon atoms or alkoxyalkoxy group having 1 to 10 carbon atoms; and

a is an integer of 0, 1 or 2.