Carrier and developer for latent electrostatic image development, container housing developer, image forming process, image forming apparatus, and process cartridge

A carrier for latent electrostatic image development, comprising:

• carrier particles, each carrier particle having:
• a core particle;
• and
• a coating layer covering the core particle,
• wherein the core particle is a ferrite particle comprising at least one of Zr in an amount of from 0.005% by mass to 4% by mass and Bi in an amount of from 0.001% by mass to 0.9% by mass, wherein the carrier particle has a magnetic moment of from 65 Am2/kg to 90 Am2/kg at 1 kilooersted and shows a dielectric breakdown voltage of 1000 V or more as determined by:
• using a measuring instrument comprising:
• a rotary sleeve housing a fixed magnet at a predetermined position and
• an electrode arranged at a distance of 1 mm from the sleeve, and
• applying a direct-current voltage to the carrier.

A carrier for latent electrostatic image development, comprising:

• carrier particles, each carrier particle having:
• a core particle;
• and
• a coating layer covering the core particle,
• wherein the core particle is a ferrite particle comprising at least one of Zr in an amount of from 0.005% by mass to 4% by mass and Bi in an amount of from 0.001% by mass to 0.9% by mass, wherein the carrier particle has a magnetic moment of from 65 Am2/kg to 90 Am2/kg at 1 kilooersted and which shows a dielectric breakdown voltage of 500 V or more as determined with a bridge measuring instrument by applying a direct-current voltage to the particles in a chain form at a distance between electrodes of from 1.7 mm to 2.3 mm in a magnetic field of 1500 gauss.

A developer, comprising:

• a toner in the form of particles each having a binder resin and a coloring agent;
• and
• a carrier having carrier particles, each carrier particle having a core particle and a coating layer covering the core particle,
• wherein the core particle is a ferrite particle comprising at least one of Zr in an amount of from 0.005% by mass to 4% by mass and Bi in an amount of from 0.001% by mass to 0.9% by mass.

A developer, comprising:

• a toner in the form of particles each having a binder resin and a coloring agent;
• and
• a carrier having carrier particles, each carrier particle having a core particle and a coating layer covering the core particle,
• wherein the core particle is a ferrite particle comprising at least one of Zr in an amount of from 0.005% by mass to 4% by mass and Bi in an amount of from 0.001% by mass to 0.9% by mass, wherein the carrier particle has a magnetic moment of from 65 Am2/kg to 90 Am2/kg at 1 kilooersted and shows a dielectric breakdown voltage of 1000 V or more as determined by:
• using a measuring instrument comprising:
• a rotary sleeve housing a fixed magnet at a predetermined position and
• an electrode arranged at a distance of 1 mm from the sleeve, and
• applying a direct-current voltage to the carrier.

A developer, comprising:

• a toner in the form of particles each having a binder resin and a coloring agent;
• and
• a carrier having carrier particles, each carrier particle having a core particle and a coating layer covering the core particle,
• wherein the core particle is a ferrite particle comprising at least one of Zr in an amount of from 0.005% by mass to 4% by mass and Bi in an amount of from 0.001% by mass to 0.9% by mass, wherein the carrier particle has a magnetic moment of from 65 Am2/kg to 90 Am2/kg at 1 kilooersted and which shows a dielectric breakdown voltage of 500 V or more as determined with a bridge measuring instrument by applying a direct-current voltage to the particles in a chain form at a distance between electrodes of from 1.7 mm to 2.3 mm in a magnetic field of 1500 gauss.

A container housing a developer, the developer comprising:

• a toner in the form of particles each having at least a binder resin and a coloring agent;
• and
• a carrier having carrier particles, each carrier particle having a core particle and a coating layer covering the core particle,
• wherein the core particle is a ferrite particle comprising at least one of Zr in an amount of from 0.005% by mass to 4% by mass and Bi in an amount of from 0.001% by mass to 0.9% by mass.

A container housing a developer, the developer comprising:

• a toner in the form of particles each having at least a binder resin and a coloring agent;
• and
• a carrier having carrier particles, each carrier particle having a core particle and a coating layer covering the core particle,
• wherein the core particle is a ferrite particle comprising at least one of Zr in an amount of from 0.005% by mass to 4% by mass and Bi in an amount of from 0.001% by mass to 0.9% by mass, wherein the carrier particle has a magnetic moment of from 65 Am2/kg to 90 Am2/kg at 1 kilooersted and shows a dielectric breakdown voltage of 1000 V or more as determined by:
• using a measuring instrument comprising:
• a rotary sleeve housing a fixed magnet at a predetermined position and
• an electrode arranged at a distance of 1 mm from the sleeve, and
• applying a direct-current voltage to the carrier.

A container housing a developer, the developer comprising:

• a toner in the form of particles each having at least a binder resin and a coloring agent;
• and
• a carrier having carrier particles, each carrier particle having a core particle and a coating layer covering the core particle,
• wherein the core particle is a ferrite particle comprising at least one of Zr in an amount of from 0.005% by mass to 4% by mass and Bi in an amount of from 0.001% by mass to 0.9% by mass, wherein the carrier particle has a magnetic moment of from 65 Am2/kg to 90 Am2/kg at 1 kilooersted and which shows a dielectric breakdown voltage of 500 V or more as determined with a bridge measuring instrument by applying a direct-current voltage to the particles in a chain form at a distance between electrodes of from 1.7 mm to 2.3 mm in a magnetic field of 1500 gauss.

An image forming apparatus, comprising:

• a latent electrostatic image bearing member for bearing a latent electrostatic image;
• a latent electrostatic image forming unit for forming a latent electrostatic image on the latent electrostatic image bearing member;
• a developing unit for developing the latent electrostatic image using a developer to form a visible image;
• a transferring unit for transferring the visible image to a recording medium;
• and
• a fixing unit for fixing the transferred image on the recording medium,
• the developer comprising:
• a toner in the form of particles each having at least a binder resin and a coloring agent;
• and
• a carrier having carrier particles, each carrier particle having a core particle and a coating layer covering the core particle,
• wherein the core particle is a ferrite particle comprising at least one of Zr in an amount of from 0.005% by mass to 4% by mass and Bi in an amount of from 0.001% by mass to 0.9% by mass.

An image forming apparatus, comprising:

• a latent electrostatic image bearing member for bearing a latent electrostatic image;
• a latent electrostatic image forming unit for forming a latent electrostatic image on the latent electrostatic image bearing member;
• a developing unit for developing the latent electrostatic image using a developer to form a visible image;
• a transferring unit for transferring the visible image to a recording medium;
• and
• a fixing unit for fixing the transferred image on the recording medium,
• the developer comprising:
• a toner in the form of particles each having at least a binder resin and a coloring agent;
• and
• a carrier having carrier particles, each carrier particle having a core particle and a coating layer covering the core particle,
• wherein the core particle is a ferrite particle comprising at least one of Zr in an amount of from 0.005% by mass to 4% by mass and Bi in an amount of from 0.001% by mass to 0.9% by mass, wherein the carrier particle has a magnetic moment of from 65 Am2/kg to 90 Am2/kg at 1 kilooersted and shows a dielectric breakdown voltage of 1000 V or more as determined by:
• using a measuring instrument comprising:
• a rotary sleeve housing a fixed magnet at a predetermined position and
• an electrode arranged at a distance of 1 mm from the sleeve, and
• applying a direct-current voltage to the carrier.

An image forming apparatus, comprising:

• a latent electrostatic image bearing member for bearing a latent electrostatic image;
• a latent electrostatic image forming unit for forming a latent electrostatic image on the latent electrostatic image bearing member;
• a developing unit for developing the latent electrostatic image using a developer to form a visible image;
• a transferring unit for transferring the visible image to a recording medium;
• and
• a fixing unit for fixing the transferred image on the recording medium,
• the developer comprising:
• a toner in the form of particles each having at least a binder resin and a coloring agent;
• and
• a carrier having carrier particles, each carrier particle having a core particle and a coating layer covering the core particle,
• wherein the core particle is a ferrite particle comprising at least one of Zr in an amount of from 0.005% by mass to 4% by mass and Bi in an amount of from 0.001% by mass to 0.9% by mass, wherein the carrier particle has a magnetic moment of from 65 Am2/kg to 90 Am2/kg at 1 kilooersted and which shows a dielectric breakdown voltage of 500 V or more as determined with a bridge measuring instrument by applying a direct-current voltage to the particles in a chain form at a distance between electrodes of from 1.7 mm to 2.3 mm in a magnetic field of 1500 gauss.

An image forming process, comprising the steps of:

• forming a latent electrostatic image on a latent electrostatic image bearing member;
• developing the latent electrostatic image using a developer to form a visible image;
• transferring the visible image to a recording medium;
• and
• fixing the transferred image on the recording medium,
• the developer comprising:
• a toner in the form of particles each having at least a binder resin and a coloring agent;
• and
• a carrier having carrier particles, each carrier particle having a core particle and a coating layer covering the core particle,
• wherein the core particle is a ferrite particle comprising at least one of Zr in an amount of from 0.005% by mass to 4% by mass and Bi in an amount of from 0.001% by mass to 0.9% by mass.

An image forming process, comprising the steps of:

• forming a latent electrostatic image on a latent electrostatic image bearing member;
• developing the latent electrostatic image using a developer to form a visible image;
• transferring the visible image to a recording medium;
• and
• fixing the transferred image on the recording medium,
• the developer comprising:
• a toner in the form of particles each having at least a binder resin and a coloring agent;
• and
• a carrier having carrier particles, each carrier particle having a core particle and a coating layer covering the core particle,
• wherein the core particle is a ferrite particle comprising at least one of Zr in an amount of from 0.005% by mass to 4% by mass and Bi in an amount of from 0.001% by mass to 0.9% by mass, wherein the carrier particle has a magnetic moment of from 65 Am2/kg to 90 Am2/kg at 1 kilooersted and shows a dielectric breakdown voltage of 1000 V or more as determined by:
• using a measuring instrument comprising:
• a rotary sleeve housing a fixed magnet at a predetermined position and
• an electrode arranged at a distance of 1 mm from the sleeve, and
• applying a direct-current voltage to the carrier.

An image forming process, comprising the steps of:

• forming a latent electrostatic image on a latent electrostatic image bearing member;
• developing the latent electrostatic image using a developer to form a visible image;
• transferring the visible image to a recording medium;
• and
• fixing the transferred image on the recording medium,
• the developer comprising:
• a toner in the form of particles each having at least a binder resin and a coloring agent;
• and
• a carrier having carrier particles, each carrier particle having a core particle and a coating layer covering the core particle,
• wherein the core particle is a ferrite particle comprising at least one of Zr in an amount of from 0.005% by mass to 4% by mass and Bi in an amount of from 0.001% by mass to 0.9% by mass, wherein the carrier particle has a magnetic moment of from 65 Am2/kg to 90 Am2/kg at 1 kilooersted and which shows a dielectric breakdown voltage of 500 V or more as determined with a bridge measuring instrument by applying a direct-current voltage to the particles in a chain form at a distance between electrodes of from 1.7 mm to 2.3 mm in a magnetic field of 1500 gauss.

A process cartridge, being attachable to and detachable from a main body of image forming apparatus and integrally comprising:

• a developing unit for developing a latent electrostatic image using a developer to form a visible image;
• and
• at least one selected from the group consisting of:
• a latent electrostatic image bearing member for bearing a latent electrostatic image;
• a latent electrostatic image forming unit for forming a latent electrostatic image on the latent electrostatic image bearing member;
• and
• a cleaning unit for cleaning,
• the developer comprising:
• a toner in the form of particles each having at least a binder resin and a coloring agent;
• and
• a carrier having carrier particles, each carrier particle having a core particle and a coating layer covering the core particle,
• wherein the core particle is a ferrite particle comprising at least one of Zr in an amount of from 0.005% by mass to 4% by mass and Bi in an amount of from 0.001% by mass to 0.9% by mass.

A process cartridge, being attachable to and detachable from a main body of image forming apparatus and integrally comprising:

• a developing unit for developing a latent electrostatic image using a developer to form a visible image;
• and
• at least one selected from the group consisting of:
• a latent electrostatic image bearing member for bearing a latent electrostatic image;
• a latent electrostatic image forming unit for forming a latent electrostatic image on the latent electrostatic image bearing member;
• and
• a cleaning unit for cleaning,
• the developer comprising:
• a toner in the form of particles each having at least a binder resin and a coloring agent;
• and
• a carrier having carrier particles, each carrier particle having a core particle and a coating layer covering the core particle,
• wherein the core particle is a ferrite particle comprising at least one of Zr in an amount of from 0.005% by mass to 4% by mass and Bi in an amount of from 0.001% by mass to 0.9% by mass, wherein the carrier particle has a magnetic moment of from 65 Am2/kg to 90 Am2/kg at 1 kilooersted and shows a dielectric breakdown voltage of 1000 V or more as determined by:
• using a measuring instrument comprising:
• a rotary sleeve housing a fixed magnet at a predetermined position and
• an electrode arranged at a distance of 1 mm from the sleeve, and
• applying a direct-current voltage to the carrier.

A process cartridge, being attachable to and detachable from a main body of image forming apparatus and integrally comprising:

• a developing unit for developing a latent electrostatic image using a developer to form a visible image;
• and
• at least one selected from the group consisting of:
• a latent electrostatic image bearing member for bearing a latent electrostatic image;
• a latent electrostatic image forming unit for forming a latent electrostatic image on the latent electrostatic image bearing member;
• and
• a cleaning unit for cleaning,
• the developer comprising:
• a toner in the form of particles each having at least a binder resin and a coloring agent;
• and
• a carrier having carrier particles, each carrier particle having a core particle and a coating layer covering the core particle,
• wherein the core particle is a ferrite particle comprising at least one of Zr in an amount of from 0.005% by mass to 4% by mass and Bi in an amount of from 0.001% by mass to 0.9% by mass, wherein the carrier particle has a magnetic moment of from 65 Am2/kg to 90 Am2/kg at 1 kilooersted and which shows a dielectric breakdown voltage of 500 V or more as determined with a bridge measuring instrument by applying a direct-current voltage to the particles in a chain form at a distance between electrodes of from 1.7 mm to 2.3 mm in a magnetic field of 1500 gauss.