Magnetic carrier and two-component developer

• US 9,058,924 B2
• Filed: 05/24/2013
• Issued: 06/16/2015
• Est. Priority Date: 05/28/2012
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Komatsu, Nozomu, Kamae, Kentaro, Ishigami, Koh, Baba, Yoshinobu
• Primary Examiner(s): Chea, Thorl
• Application Number:
  US13/902,365
• Publication Number:
  US 20140030650A1
• Time in Patent Office: 753 Days
• Field of Search: 430/111.32, 430/111.35
• US Class Current: 1/1
• CPC Class Codes: G03G 9/0833 Oxides
• CPC Class Codes: G03G 9/1075 Structural characteristics of the carrier particles, e.g. shape or crystallographic structure
• CPC Class Codes: G03G 9/1085 with non-ferrous metal oxide, e.g. MgO-Fe2O3
• CPC Class Codes: G03G 9/1131 Coating methods; Structure of coatings
• CPC Class Codes: H01F 1/01 of inorganic materials H01F1/44 takes precedence

Abstract

A magnetic carrier having a resin-containing ferrite particles each containing a porous ferrite core and a resin in pores of the porous ferrite core, wherein the porous ferrite core has a particular pore diameter corresponding to the maximum logarithmic differential pore volume in a pore diameter range from at least 0.10 μm to not more than 3.00 μm, the resistivity of the porous ferrite core is in a particular range, and the porous ferrite core contains an oxide of Mg in a particular amount and contains a particular amount of a oxide of at least one metal selected from the group consisting of Mn, Sr, and Ca.

Claims

1. A magnetic carrier comprising resin-containing ferrite particles each comprising a porous ferrite core having pores and a resin contained in the pores thereof,

wherein:

in a pore diameter distribution of the pores measured by using a mercury intrusion method,

a pore diameter at which a logarithmic differential pore volume shows the maximum value in the pore diameter range of from at least 0.10 μ

m to not more than 3.00 μ

m, is present within the pore diameter range of from at least 0.80 μ

m to not more than 1.50 μ

m,

when P1 is a maximum value of a logarithmic differential pore volume in a pore diameter range of from at least 0.80 μ

m to not more than 1.50 μ

m, and

P2 is a minimum value of a logarithmic differential pore volume in a pore diameter range of from at least 2.00 μ

m to not more than 3.00 μ

m,

the porous ferrite core exhibits the P1 of from at least 0.07 mL/g to not more than 0.35 mL/g, and P2/P1 of from at least 0.05 to not more than 0.35

the porous ferrite core

i) has a resistivity at 100 V/cm of from at least 8.0×

10⁴ Ω

·

cm to not more than 1.0×

10⁶ Ω

·

cm,

ii) contains an oxide of Mg of from at least 1.00 mass % to not more than 15.00 mass % as MgO with reference to a mass of the porous ferrite core, and

iii) contains a metal oxide, the metal being at least one metal selected from the group consisting of Mn, Sr, and Ca, and a total content of the metal oxide as MnO, SrO and CaO is from at least 0.02 mass % to not more than 1.50 mass % with reference to a mass of the porous ferrite core.

2. The magnetic carrier according to claim 1, wherein, in a pore diameter distribution of the pores measured by using a mercury intrusion method, the porous ferrite core has a pore volume of from at least 0.04 mL/g to not more than 0.10 mL/g in a pore diameter range from at least 0.10 μ

m to not more than 3.00 μ

m.

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