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Mg-based ferrite, an electrophotographic development carrier containing the ferrite, and developer containing the carrier

A magnesium-based ferrite, electrophotography technology, applied in the direction of developer, electrical recording, optics, etc., can solve the problem of low saturation magnetization

Active Publication Date: 2008-02-06
KANTO DENKA IND CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although this magnesium-based ferrite has a high dielectric breakdown voltage, it has a low saturation magnetization of 20-25emu / g

Method used

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  • Mg-based ferrite, an electrophotographic development carrier containing the ferrite, and developer containing the carrier

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preparation example Construction

[0081] The preparation process of the present invention includes the step i) of mixing raw materials and at least two heating steps: step ii) sintering the mixed raw materials under an inert atmosphere to grow particles, and step iii) heating the sintered raw materials in an oxygen-containing atmosphere to control And adjust its properties such as oxidation number of each metal, crystal structure, occupancy of each site and magnetic structure well. By adjusting the conditions of the sintering and heating steps, such as oxygen concentration, sintering temperature, sintering cycle, heat treatment temperature, and heat treatment period, it is possible to obtain the desired properties of the magnetic carrier, including dielectric breakdown voltage and saturation magnetization. For example, the desired support properties can be obtained by performing step iii) in an atmosphere of higher oxygen concentration than in step ii) and setting the maximum temperature of step ii) higher than...

Embodiment 1 to 27

[0098] Use MgO, Fe as shown in Table 1 2 o 3 , CaO and additives as raw materials to prepare magnesium-based ferrite materials. First, raw materials were weighed to obtain predetermined compositions as listed in Table 1. Then weighed raw materials were added to water together with binder (polyvinyl alcohol), dispersant and defoamer; ground and mixed in a wet ball mill for 4 hours to prepare a slurry. The concentration of the slurry was 50 wt%. Based on the total amount of raw materials in the slurry, the amount of the defoamer is 0.1 wt%, and the amount of the dispersant is 0.15 wt%.

[0099] The obtained slurry was dried and granulated by a spray dryer to prepare spherical granules. These spherical pellets were sintered in an electric furnace at 1200°C in a nitrogen atmosphere. The oxygen concentration in the nitrogen atmosphere is 1000 ppm or less. The sintered material was heated at 500°C in a nitrogen atmosphere having an oxygen concentration of 20 vol%. Then, the m...

Embodiment 28

[0121] Preparation of magnesium-based ferrite materials:

[0122] Using MgO, Fe 2 o 3 , CaO and the additives described in Table 3 to manufacture magnesium-based ferrite materials. First, these raw materials were weighed to obtain predetermined compositions as listed in Table 3. The weighed raw materials were added to water together with a binder (polyvinyl alcohol), a dispersant and an antifoaming agent; and ground and mixed in a wet ball mill for 4 hours to prepare a slurry. The concentration of the slurry was 50 wt%. Based on the total amount of raw materials in the slurry, the amount of the defoamer is 0.1 wt%, and the amount of the dispersant is 0.15 wt%.

[0123] The obtained slurry was dried and granulated by a spray dryer to prepare spherical granules. These spherical pellets were sintered in an electric furnace at 1300° C. under a nitrogen atmosphere. The oxygen concentration in this nitrogen atmosphere is 1000 ppm or less. The sintered material was heated at 4...

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Abstract

The present invention provides a magnesium-based ferrite having a high dielectric breakdown voltage and a saturation magnetization suitable for electrophotographic development, a carrier containing the ferrite, and an electrophotographic developer containing the carrier. The magnesium-based ferrite material of the present invention contains Li, Na, K, Rb, Cs, Ca, Sr, Ba, Y, La, Ti, Zr, Hf, V, Nb, Ta, Al, Ga, Si, Ge, P, Sb, Bi or combinations thereof. The saturation magnetization of the magnesium-based ferrite material is 30 to 80 emu / g, and the dielectric breakdown voltage is 1.5 to 5.0 kV. The magnesium-based ferrite material achieves high image quality and meets environmental regulations.

Description

technical field [0001] The invention relates to a magnesium-based ferrite magnetic material, which can be used as a carrier of a two-component developer and used in electrophotographic developing equipment, such as copiers and printers. The invention also relates to an electrophotographic developer comprising said carrier material. Background technique [0002] The electrophotographic method includes: forming an electrostatic latent image on a photoreceptor; depositing toner onto the latent image to form a visible image; and then transferring the toner image to a target. Electrophotography includes two main classifications: two-component development and one-component development. In two-component development, the developer contains two components, carrier and toner, and the carrier commonly used is a magnetic carrier. [0003] In two-component development with a magnetic carrier, the developer is stirred and mixed in a developing container to electrostatically charge the t...

Claims

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Application Information

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IPC IPC(8): H01F1/34C04B35/26G03G9/00H01F1/36
Inventor 饭沼秀彦林政友松浦夏树小熊幸成
Owner KANTO DENKA IND CO LTD
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