Electrostatic charge image developer, developer cartridge, process cartridge, image forming apparatus, and image forming method

Inventors: Yosuke Tsurumi (Kanagawa, JP); Yasuo Kadokura (Kanagawa, JP); Moegi Iguchi (Kanagawa, JP)

Assignee: FUJIFILM Business Innovation Corp.

G03G9/1133 G03G9/0825 G03G9/1085

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Quick Facts

Patent No.: US 12663735
App. No.: 18/453,339
Granted: Jun 23, 2026
Kind: B2

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Abstract

An electrostatic charge image developer contains a toner including toner particles that contain a binder resin and a carrier including magnetic particles and a resin layer that adheres to a surface of the magnetic particles, in which, in a dynamic viscoelasticity measurement of the toner, in a case where a loss tangent tanδ at a temperature of 90° C. and a strain of 1% is represented by D1 (90), a loss tangent tanδ at a temperature of 90° C. and a strain of 50% is represented by D50 (90), a loss tangent tanδ at a temperature of 150° C. and a strain of 1% is represented by D1 (150), and a loss tangent tanδ at a temperature of 150° C. and a strain of 50% is represented by D50 (150), each of D1 (90), D50 (90), D1 (150), and D50 (150) is 0.5 or more and 2.5 or less, a value of D50 (150)−D1 (150) is less than 1.5, and a value of D50 (90)−D1 (90) is less than 1.0, and in the surface of the magnetic particles, an average unevenness interval Sm and an arithmetic mean roughness Ra satisfy 0.5 μm≤ Sm≤2.5 μm and 0.3 μm≤ Ra≤1.2 μm.

Claims (79)

1 . An electrostatic charge image developer comprising:

a toner including toner particles that contain a binder resin; and

a carrier including magnetic particles and a resin layer that adheres to a surface of the magnetic particles,

wherein, the binder resin contains a crystalline resin and an amorphous resin, the toner particles have a storage elastic modulus G′ of 1×10 8 Pa or greater in the temperature range of 30 to 50° C., and

in a dynamic viscoelasticity measurement of the toner, in a case where a loss tangent tanδ at a temperature of 90° C. and a strain of 1% is represented by D1 (90), a loss tangent tanδ at a temperature of 90° C. and a strain of 50% is represented by D50 (90), a loss tangent tanδ at a temperature of 150° C. and a strain of 1% is represented by D1 (150), and a loss tangent tanδ at a temperature of 150° C. and a strain of 50% is represented by D50 (150),

each of D1 (90), D50 (90), D1 (150), and D50 (150) is 0.5 or more and 2.5 or less,

a value of D50 (150)−D1 (150) is less than 1.5, and

a value of D50 (90)−D1 (90) is less than 1.0, and

in the surface of the magnetic particles, an average unevenness interval Sm and an arithmetic mean roughness Ra satisfy 0.5 μm≤Sm≤2.5 μm and 0.3 μm≤Ra≤1.2 μm.

2 . The electrostatic charge image developer according to claim 1 ,

wherein a relationship between D1 (90) and the average unevenness interval Sm satisfies the following expression (1),

D 1(90)≤Sm≤ D 1(90)+1.1 the expression (1):

3 . The electrostatic charge image developer according to claim 1 ,

wherein a relationship between D1 (90) and the arithmetic mean roughness Ra satisfies the following expression (2),

1.05−0.3× D 1(90)≤Ra≤1.36−0.3× D 1(90) the expression (2):

4 . The electrostatic charge image developer according to claim 3 ,

wherein a relationship between D50 (150) and the arithmetic mean roughness Ra satisfies the following expression (3),

1.05−0.3× D 50(150)≤Ra≤1.36−0.3× D 50(150) the expression (3):

5 . The electrostatic charge image developer according to claim 1 ,

wherein an exposed area ratio of the magnetic particles on a surface of the carrier is 4% or more and 20% or less.

6 . The electrostatic charge image developer according to claim 1 ,

wherein the toner particles further contain resin particles.

7 . The electrostatic charge image developer according to claim 6 ,

wherein the resin particles are crosslinked resin particles.

8 . The electrostatic charge image developer according to claim 7 ,

wherein the crosslinked resin particles are styrene (meth)acrylic resin particles.

9 . The electrostatic charge image developer according to claim 1 ,

wherein a number-average molecular weight of tetrahydrofuran-soluble components in the toner particles is 5,000 or more and 15,000 or less.

10 . A developer cartridge comprising:

a container that contains the electrostatic charge image developer according to claim 1 as a replenishing developer,