# US 12,222,678 B2 · Magnetic carrier, two-component developer, and replenishment developer

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- Number: US 12,222,678 B2
- Document ID: US12222678B2
- Status: Granted
- Kind: B2
- Application number: 17/582,691
- Filed: 2022-01-24
- Published: 2022-07-28
- Granted: 2025-02-11
- Earliest claimed: 2021-01-28
- Assignees: Canon Kabushiki Kaisha
- Applicants: Canon Kabushiki Kaisha
- Inventors: Ryuji Murayama; Yuto Onozaki; Nobuhiro Yoshida; Hironori Minagawa
- Web page: https://patentgrep.com/patent/US12222678B2

## CPC

- G03G 9/1133: {obtained by reactions only involving carbon-to-carbon unsaturated bonds}
- G03G 9/108: {Ferrite carrier, e.g. magnetite}
- G03G 9/1085: {with non-ferrous metal oxide, e.g. MgO-Fe2O3}
- G03G 9/1131: {Coating methods; Structure of coatings}
- G03G 9/1136: {containing silicon atoms}
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## Abstract

A magnetic carrier includes a magnetic core and a coating resin that covers a surface of the magnetic core. The coating resin includes a resin A and a resin B. A content of the resin A is 1 to 50% by mass, and a content of the resin B is 50 to 99% by mass, with respect to the coating resin. The resin A has a particular unit Y1 and a particular unit Y2, and the resin B contains 0.1% by mass or less of the particular unit Y2. When a mass of the resin A is represented by X, a mass of the unit Y1 is represented by Ma, and a mass of the unit Y2 is represented by Mb, 0.90≤(Ma+Mb)/X≤1.00 and 1.00≤Ma/Mb≤30.0 are satisfied, and also 0≤|SPa−SPb|≤2.0 is satisfied.

## Claims

### Claim 1

A magnetic carrier comprising:
a magnetic core; and
a coating resin that covers a surface of the magnetic core,
wherein:
the coating resin comprises a resin A and a resin B;
a content of the resin A is 1 to 50% by mass, and a content of the resin B is 50 to 99% by mass, with respect to the total mass of the coating resin;
the resin A has a unit Y1 represented by formula (1) and a unit Y2 represented by formula (2), and
in the resin B, a content of the unit Y2 represented by formula (2) is 0.1% by mass or less; and
when a mass of the resin A, a mass of the unit Y1 in the resin A, and a mass of the unit Y2 in the resin A are represented by X, Ma and Mb, respectively, the X, the Ma and the Mb satisfy expressions (a) and (b):
0.90≤(Ma+Mb)/X≤1.00 (a), and
1.00≤Ma/Mb≤30.0 (b),
and
when an SP value of the unit Y1 and an SP value of the resin B are represented by SPa and SPb, respectively, the SPa and the SPb satisfy expression (c):
0≤|SPa−SPb|≤2.0 (c),
wherein in formula (1),
R1 represents H or CH3, and
R2 represents a hydrocarbon group having 1 to 8 carbon atoms and optionally having a substituent, wherein the substituent is a hydroxy group or a carboxy group; and
in formula (2),
R3 represents H or CH3,
R4 represents H or CH3,
R5 represents a single bond or a hydrocarbon group having 1 to 10 carbon atoms,
R6 represents a hydrocarbon group having 1 to 10 carbon atoms,
R7 represents H, CH3 or Si(CH3)3, and
n represents an integer of 2 to 150

### Claim 2 (depends on 1)

The magnetic carrier according to claim 1, wherein
the resin B comprises 75% by mass or more of the unit Y1 represented by formula (1).

### Claim 3 (depends on 1)

The magnetic carrier according to claim 1, wherein n in formula (2) is 5 or larger and 60 or smaller.

### Claim 4 (depends on 1)

The magnetic carrier according to claim 1, wherein Si on the surface of the magnetic carrier as measured by electron spectroscopy for chemical analysis (ESCA) is 1.0 to 15.0 atom %.

### Claim 5 (depends on 1)

The magnetic carrier according to claim 1, wherein when a sum of numbers of the units Y1 and the units Y2 represented by formula (1) and formula (2) is represented by m, the following expression is satisfied:
50≤m≤250.

### Claim 6 (depends on 1)

The magnetic carrier according to claim 1, wherein the coating resin contains 1 to 20% by mass of the resin A and contains 80 to 99% by mass of the resin B.

### Claim 7 (depends on 1)

The magnetic carrier according to claim 1, wherein the resin B comprises a unit Y3 represented by following formula (3), and the content of the unit Y3 is 1 to 75% by mass based on the resin B:
wherein R8 represents a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclopentyl group, a cyclobutyl group or a cyclopropyl group.

### Claim 8 (depends on 1)

The magnetic carrier according to claim 1, wherein the resin B comprises a polymer in which a styrene-acrylic resin is graft-polymerized to polypropylene.

### Claim 9

A two-component developer comprising a magnetic carrier and toner, wherein
the magnetic carrier comprises:
a magnetic core; and
a coating resin that covers a surface of the magnetic core,
wherein:
the coating resin comprises a resin A and a resin B;
a content of the resin A is 1 to 50% by mass, and a content of the resin B is 50 to 99% by mass, with respect to the total mass of the coating resin;
the resin A has a unit Y1 represented by formula (1) and a unit Y2 represented by formula (2), and
in the resin B, a content of the unit Y2 represented by formula (2) is 0.1% by mass or less; and
when a mass of the resin A, a mass of the unit Y1 in the resin A, and a mass of the unit Y2 in the resin A are represented by X, Ma and Mb, respectively, the X, the Ma and the Mb satisfy expressions (a) and (b):
0.90≤(Ma+Mb)/X≤1.00 (a), and
1.00≤Ma/Mb≤30.0 (b),
and
when an SP value of the unit Y1 and an SP value of the resin B are represented by SPa and SPb, respectively, the SPa and the SPb satisfy expression (c):
0≤|SPa−SPb|≤2.0 (c),
wherein in formula (1),
R1 represents H or CH3, and
R2 represents a hydrocarbon group having 1 to 8 carbon atoms and optionally having a substituent, wherein the substituent is a hydroxy group or a carboxy group; and
in formula (2),
R3 represents H or CH3,
R4 represents H or CH3,
R5 represents a single bond or a hydrocarbon group having 1 to 10 carbon atoms,
R6 represents a hydrocarbon group having 1 to 10 carbon atoms,
R7 represents H, CH3 or Si(CH3)3, and
n represents an integer of 2 to 150

### Claim 10

A replenishment developer comprising a magnetic carrier, wherein
the magnetic carrier comprising:
a magnetic core; and
a coating resin that covers a surface of the magnetic core,
wherein:
the coating resin comprises a resin A and a resin B;
a content of the resin A is 1 to 50% by mass, and a content of the resin B is 50 to 99% by mass, with respect to the total mass of the coating resin;
the resin A has a unit Y1 represented by formula (1) and a unit Y2 represented by formula (2), and
in the resin B, a content of the unit Y2 represented by formula (2) is 0.1% by mass or less; and
when a mass of the resin A, a mass of the unit Y1 in the resin A, and a mass of the unit Y2 in the resin A are represented by X, Ma and Mb, respectively, the X, the Ma and the Mb satisfy expressions (a) and (b):
0.90≤(Ma+Mb)/X≤1.00 (a), and
1.00≤Ma/Mb≤30.0 (b),
and
when an SP value of the unit Y1 and an SP value of the resin B are represented by SPa and SPb, respectively, the SPa and the SPb satisfy expression (c):
0≤|SPa−SPb|≤2.0 (c),
wherein in formula (1),
R1 represents H or CH3, and
R2 represents a hydrocarbon group having 1 to 8 carbon atoms and optionally having a substituent, wherein the substituent is a hydroxy group or a carboxy group; and
in formula (2),
R3 represents H or CH3,
R4 represents H or CH3,
R5 represents a single bond or a hydrocarbon group having 1 to 10 carbon atoms,
R6 represents a hydrocarbon group having 1 to 10 carbon atoms,
R7 represents H, CH3 or Si(CH3)3, and
n represents an integer of 2 to 150