MAGNETIC CARRIER AND TWO-COMPONENT DEVELOPER

• US 20100028796A1
• Filed: 08/04/2009
• Published: 02/04/2010
• Est. Priority Date: 08/04/2008
• Status: Abandoned Application

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Inoue, Chika, Ishigami, Koh, Baba, Yoshinobu, Nakamura, Kunihiko, Endo, Tomoko, Itakura, Takayuki, Fujikawa, Hiroyuki, Komatsu, Nozomu
• Application Number:
  US12/534,947
• Publication Number:
  US 20100028796A1
• Time in Patent Office: Days
• US Class Current: 430/110.300
• CPC Class Codes: G03G 9/1075 Structural characteristics of the carrier particles, e.g. shape or crystallographic structure
• CPC Class Codes: G03G 9/1136 containing silicon atoms

Abstract

A magnetic carrier and two-component developer are provided alleviating coarse images, fogging when printing is done after a copier body is left standing for one week in a high temperature and high humidity environment and carrier adhesion after extensive operation in a low image ratio. The magnetic carrier includes magnetic carrier particles including porous magnetic core particles and a resin, wherein in a mercury intrusion method applied to the porous magnetic core particles, a pore diameter in which a differential pore volume in the specific pore diameter range becomes maximum is in a specific range, and when the maximum value of a differential pore volume in the specific pore diameter range is defined as P1 and the maximum value of a differential pore volume in the specific pore diameter range is defined as P2, P1 is in a specific range and the ratio P2/P1 is in a specific range.

Claims

1. A magnetic carrier comprising magnetic carrier particles comprising at least porous magnetic core particles and a resin, wherein

in a mercury intrusion method applied to the porous magnetic core particles, a pore diameter in which a differential pore volume in a pore diameter range of 0.10 μ

m or more and 3.00 μ

m or less is maximum is from 0.80 μ

m or more and 1.5 μ

m or less, and

where a maximum value of a differential pore volume in a pore diameter range of 0.80 μ

m or more and 1.50 μ

m or less is defined as P1 and a maximum value of a differential pore volume in a pore diameter range of 2.00 μ

m or more and 3.00 μ

m or less is defined as P2, P1 is 0.05 ml/g or more and 0.50 ml/g or less and a ratio P2/P1 is 0.05 or more and 0.30 or less.

2. The magnetic carrier according to claim 1, wherein electric field intensity immediately before breakdown of the porous magnetic core particles is 400 V/cm or more and 2000 V/cm or less.

3. The magnetic carrier according to claim 1, wherein the resin contains at least a silicone resin.

4. The magnetic carrier according to claim 1, wherein the surface of the magnetic carrier is further coated with a resin.

5. A two-component developer comprising a magnetic carrier and a toner, wherein the magnetic carrier is a magnetic carrier according to claim 1.

6. The two-component developer according to claim 5, wherein, when circularities of the toner are measured with a flow-type particle image analyzer having an image processing resolution of 512×

512 pixels (0.37 μ

m×

0.37 μ

m per pixel) and the circularities thus measured in a range of 0.200 or more and 1.000 or less are divided into 800 and analyzed, an average circularity of the toner having a circle-equivalent diameter of 1.985 μ

m or more and less than 39.69 μ

m has is 0.940 or more and 1.000 or less.