Magnetic carrier, two-component developer, and developer for replenishment

• US 8,974,994 B2
• Filed: 01/28/2013
• Issued: 03/10/2015
• Est. Priority Date: 01/31/2012
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Ishigami, Koh, Baba, Yoshinobu, Kamae, Kentaro
• Primary Examiner(s): Chapman, Mark A
• Application Number:
  US13/752,129
• Publication Number:
  US 20130196265A1
• Time in Patent Office: 771 Days
• Field of Search: 430/111.35
• 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 9/1133 obtained by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: G03G 9/1139 Inorganic components of coatings

Abstract

Provided is a magnetic carrier satisfactory in terms of the suppression of leakage and solid carrier adhesion, charge-providing performance, and developability. The magnetic carrier is a magnetic carrier, including filled core particles of which pores of porous magnetic core particles are filled with a filling resin composition, and having a surface coated with a coating resin composition, in which the coating resin composition comprises a coating resin and a carbon black, an amount of the coating resin composition is 2.0 parts by mass or more and 5.0 parts by mass or less with respect to 100.0 parts by mass of the filled core particles; and a particle diameter of the carbon black in the coating resin composition Pv at a maximum frequency in a particle size distribution based on a volume of the carbon black is 1.0 μm or more and 10.0 μm or less.

Claims

1. A magnetic carrier, comprising

filled core particles of which pores of porous magnetic core particles are filled with a filling resin composition, and having a surface coated with a coating resin composition,

wherein the coating resin composition comprises a coating resin and a carbon black,

an amount of the coating resin composition covering the surface of the filled core particles is 2.0 parts by mass or more and 5.0 parts by mass or less with respect to 100.0 parts by mass of the filled core particles;

and

a particle diameter of the carbon black in the coating resin composition covering the surface of the filled core particles Pv at a maximum frequency in a particle size distribution based on a volume of the carbon black is 1.0 μ

m or more and 10.0 μ

m or less, and

wherein the coating resin in the coating resin composition has a repeating structural unit derived from a monomer having a cyclic hydrocarbon group.

2. The magnetic carrier according to claim 1, wherein a content of the carbon black is 10.0 parts by mass or more and 30.0 parts by mass or less with respect to 100.0 parts by mass of the coating resin.

3. The magnetic carrier according to claim 1, wherein the coating resin in the coating resin composition comprises a graft polymer.

4. A two-component developer, comprising

a magnetic carrier;

and

a toner,

wherein the toner has toner particles, each of which contains at least a binding resin, a coloring agent, and a wax, and inorganic fine powders; and

the magnetic carrier comprises the magnetic carrier according to claim 1.

5. A developer for replenishment, comprising a magnetic carrier and a toner, the developer for replenishment being used in an image-forming method including performing image formation while replenishing a developing unit with the developer for replenishment as required and discharging the magnetic carrier that becomes excessive in the developing unit from the developing unit as required,

wherein the developer for replenishment contains 2.0 parts by mass or more and 50.0 parts by mass or less of the toner with respect to 1.0 part by mass of the magnetic carrier;

the toner has toner particles, each of which contains at least a binding resin, a coloring agent, and a wax, and inorganic fine powders; and

the magnetic carrier comprises the magnetic carrier according to claim 1.