Carrier for developing electrostatic charge image, developer for electrostatic charge image, process cartridge and image forming apparatus
View Patent ↗A carrier for developing an electrostatic charge image, including a core, and a coating layer including a resin and inorganic oxide particles that exhibit electroconductivity, by which the core is coated, wherein the inorganic oxide particles have, when they are aggregated, an aggregation size of, or when they are not aggregated, a primary particle size of, from 230 nm to 970 nm.
1. A carrier for developing an electrostatic charge image, comprising:
a core; and
a coating layer comprising a resin and inorganic oxide particles that exhibit electroconductivity, by which the core is coated,
wherein
the inorganic oxide particles have, when they are aggregated, an aggregation size of, or when they are not aggregated, a primary particle size of, from 230 nm to 970 nm, and
the inorganic oxide particles in the coating layer have, when they are aggregated, a particle size distribution (GSD) of the aggregation size of, or when the particles are not aggregated, a particle size distribution (GSD) of the primary particle size of, 2.0 or more.
2. The carrier for developing an electrostatic charge image according to claim 1 , wherein the inorganic oxide particles have an aggregation size of from 230 nm to 970 nm, and a ratio of the aggregation size to the primary particle size of the inorganic oxide is from 2.8 to 7.5.
3. The carrier for developing an electrostatic charge image according to claim 1 , wherein a content of the inorganic oxide particles is from 0.2% by mass to 10% by mass with respect to the carrier.
4. The carrier for developing an electrostatic charge image according to claim 1 , wherein the inorganic oxide particles include tin oxide.
5. The carrier for developing an electrostatic charge image according to claim 1 , wherein the resin includes a polymer including repeating units derived from a methacrylic acid ester having an alicyclic group.
6. The carrier for developing an electrostatic charge image according to claim 5 , wherein a weight average molecular weight of the polymer including repeating units derived from the methacrylic acid ester having an alicyclic group is from 4.0×10 4 to 3.0×10 5 .
7. The carrier for developing an electrostatic charge image according to claim 5 , wherein the methacrylic acid ester having an alicyclic group comprises cyclohexyl methacrylate.
8. The carrier for developing an electrostatic charge image according to claim 5 , wherein a thickness of the coating layer is from 0.3 μm to 10 μm.
9. The carrier for developing an electrostatic charge image according to claim 1 , wherein the core includes magnetic particles.
10. The carrier for developing an electrostatic charge image according to claim 9 , wherein the magnetic particles include ferrite.
11. The carrier for developing an electrostatic charge image according to claim 9 , wherein a particle size of the magnetic particles is from 0.01 μm to 1 μm.
12. The carrier for developing an electrostatic charge image according to claim 1 , wherein a magnetic force of the carrier at 1 kOe is from 170 emu/cm 3 to 250 emu/cm 3 .
13. The carrier for developing an electrostatic charge image according to claim 1 , wherein a sphericity of the carrier is from 0.980 to 1.000.
14. The carrier for developing an electrostatic charge image according to claim 1 , wherein a volume resistivity of the carrier is from 1×10 7 Ωcm to 1×10 14 Ωcm.
15. A developer for an electrostatic charge image, comprising a toner and the carrier for developing an electrostatic charge image according to claim 1 .
16. A process cartridge comprising a developing device, wherein the developer for an electrostatic charge image according to claim 15 is housed in the developing device.