MAGNETIC CARRIER AND TWO-COMPONENT DEVELOPER

• US 20140134535A1
• Filed: 01/17/2014
• Published: 05/15/2014
• Est. Priority Date: 08/08/2012
• Status: Abandoned Application

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Baba, Yoshinobu, Ishigami, Koh, Hama, Masayuki, Kamae, Kentaro, Kawakami, Hiroaki
• Application Number:
  US14/158,183
• Publication Number:
  US 20140134535A1
• Time in Patent Office: Days
• US Class Current: 430/111.35
• CPC Class Codes: G03G 9/1075 Structural characteristics of the carrier particles, e.g. shape or crystallographic structure
• CPC Class Codes: G03G 9/108 Ferrite carrier, e.g. magnetite
• CPC Class Codes: G03G 9/10884 Binder is obtained other than by reactions only involving carbon-carbon unsaturated bonds
• 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

Abstract

Provided is a magnetic carrier satisfying leakage, white spots, charging property and high developing performance in a low electric field and having excellent durability. The magnetic carrier is a magnetic carrier comprising a magnetic substance-dispersed resin carrier core containing a magnetic substance and a binder resin, and a coating resin on a surface thereof, wherein the magnetic substance comprises a magnetic substance A having a shape without vertexes and a magnetic substance B having a shape with vertexes, the magnetic substance B has a number average particle diameter of 0.40-2.00 μm, and in a reflection electron image of a section of the magnetic substance-dispersed resin carrier core taken by a scanning electron microscope, an area proportion of the magnetic substance B is larger than an area proportion of the magnetic substance A within a region from the surface of the magnetic substance-dispersed resin carrier core to a depth of 1.0 μm.

Claims

1. A magnetic carrier comprising:

a magnetic substance-dispersed resin carrier core, which contains a magnetic substance and a binder resin, and

a coating resin on a surface thereof,

wherein;

the magnetic substance comprises

a magnetic substance A having a shape without vertexes and

a magnetic substance B having a shape with vertexes,

the magnetic substance B has a number average particle diameter of 0.40 μ

m or more and 2.00 μ

m or less, and

in a reflection electron image of a section of the magnetic substance-dispersed resin carrier core taken by a scanning electron microscope,

an area proportion of the magnetic substance B is larger than an area proportion of the magnetic substance A within a region from the surface of the magnetic substance-dispersed resin carrier core to a depth of 1.0 μ

m.

2. The magnetic carrier according to claim 1, wherein within the region, a proportion of the magnetic substance having a horizontal Feret diameter of 0.50 μ

m or more is 70 area % or more based on an area proportion of all magnetic substances having a horizontal Feret diameter of 0.10 μ

m or more.

3. The magnetic carrier according to claim 1, wherein within the region, a proportion of a binder resin portion is 40% or more and 80% or less with respect to a sum of an area of the binder resin portion and a magnetic substance portion.

4. The magnetic carrier according to claim 1, wherein the magnetic substance A has a number average particle diameter of 0.15 μ

m or more and 0.40 μ

m or less.

5. The magnetic carrier according to claim 4, wherein the number average particle diameter of the magnetic substance A is 0.20 μ

m or more and 0.35 μ

m or less.

6. The magnetic carrier according to claim 1, wherein a content of the magnetic substance B is 10% by mass or more and 40% by mass or less with respect to a total amount of the magnetic substance A and the magnetic substance B.

7. The magnetic carrier according to claim 1, wherein the coating resin comprises a resin having a unit derived from a monomer having a cyclic hydrocarbon group as a repeating unit.

8. A two-component developer comprising a toner and the magnetic carrier according to claim 1.