Title: Magnetic toner for electrophotography

Abstract: An insulating magnetic toner useful as a one component developer for electro-photography consisting essentially of a ferro-magnetic material, a resin and a charge controlling agent. The preferred toner mixture has an average particle size in the range from about 7 to about 30 .mu.m and is substantially free of particles having a size smaller than 1 .mu.m. The toner is preferably prepared by mixing a ferromagnetic material, a resin and a charge controlling agent, heat kneading, cooling and then granulating the mixture to form fine particles, contacting the pacticles with a hot gas of a temperature higher than the toner softening point and lower than 500.degree. C to fuse particles smaller than about 1 .mu.m to larger particles, cooling and selecting the particles of an average particle size of about 7 to about 30 .mu.m.

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Inventors: Uetake, Shigeru
Tozawa, Katsutoshi
Sato, Keiji

Application Number: 874151
Filing Date: 1978-02-01
Publication_date: 1979-01-30
Assignee:
Primary Class(es): 430/110.4 252/62, 252/62.54, 264/15, 264/117, 427/213, 430/903
Other Classes:
US Patent Ref:

3196032	Jul, 1965	Seymour	252/62.
3627682	Dec, 1971	Hall et al.	252/62.
3639245	Feb, 1972	Nelson	252/62.
3645770	Feb, 1972	Flint	96/1.
3674736	Jul, 1972	Lerman et al.	252/62.
3909258	Sep, 1975	Kutz	96/1.

Other Refs: 2538112

Mar, 1976	DE

Primary Examiner: Goolkasian, John T.
Assistant Examiner:
Attorney: Nilles; James E.