Interdispersed two-phase ferrite composite and electrographic magnetic carrier particles therefrom

Patent 5106714 Issued on April 21, 1992. Estimated Expiration Date:

August 1, 2010. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

Composites of coercive particles and superparamagnetic particles
Patent #: 4824587
Issued on: 04/25/1989
Inventor: Kwon , et al.

Composite magnetic powder, method for producing the same and recording medium containing the same Patent #: 4957812
Issued on: 09/18/1990
Inventor: Aoki, et al.

Inventors

Application

No. 561382 filed on 08/01/1990

US Classes:

430/111.31, Ferrite containing magnetic carrier252/62.57, With scandium, yttrium, gallium, rare earth, or actinide430/111.4Identified physical parameter of carrier particle or dry toner particle, etc. (Tg, MW, coercivity, density, etc.)

Examiners

Primary: McCamish, Marion E.
Assistant: Rasasco, S.

Attorney, Agent or Firm

Montgomery; Willard G.

International Class

G03G 009/10

Abstract

Disclosed is an interdispersed two-phase ferrite composite which comprises about 0.1 mole to about 1.0 mole of a spinel phase having the general formula MFe2 O4 where M is at least one element that forms a spinel ferrite and is selected from the group consisting of cobalt, manganese, iron and mixtures thereof, to about 2.5 moles of a magnetoplumbite phase having the general formula PO.6Fe2 O3, where P is selected from the group consisting of stontium, barium, calcium, lead and mixtures thereof.Also disclosed are carrier particles formed from magnetized particles of the composite which optionally can be polymerically coated, an electrostatic two-component dry developer composition comprising charged toner particles mixed with oppositely charged carrier particles formed from magnetized, and optionally polymerically coated, particles of the composite, and a method of developing an electrostastic image by contacting the image with a two-component dry developer composition described above.