Patent US4518674A successfully refreshed from Google Patents.
US4518674A
Expired / Lapsed
US
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Developing material for electrophotography, process for preparation
Assignee: Konica Minolta Inc
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Filing: 1984-03-26
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Granted: 1985-05-21
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Expires: 2004-03-26
Abstract
Abstract An iron powder developer carrier for electrophotography having at least the outer surface thereof coated with iron oxide. The iron oxide has a particle size of 50 to 200 mu , an apparent density of 1.5 to 2.5 g/cm3 and a specific surface area of 0.01 to 0.3 m2/g. A process for the preparation of iron powder developer carriers for electrophotography, which comprises the steps of subjecting a starting iron powder to a primary calcination treatment in an inert gas atmosphere without using a binder, pulverizing and classifying said calcination product to prepare an intermediate iron powder, reducing the intermediate iron powder in a reducing atmosphere and washing the intermediate iron powder, and subjecting the intermediate iron powder to an oxidizing calcination treatment.
Inventors
- 👤 Shotaro Watanabe
- 👤 Makoto Tomono
- 👤 Goichi Yamakawa
- 👤 Takeo Nishimura
- 👤 Nobuo Takahashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 12:27
CPC Classifications
G; G03; G03G; G03G9/00; G03G9/08; G03G9/10; G03G9/107; G03G9/1075; Y; Y10; Y10T; Y10T428/00; Y10T428/29; Y10T428/2982; Y10T428/2991
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
153 words
A process for the preparation of iron powder developer carriers for electrophotography, which comprises the steps of subjecting a starting iron powder pulverized to a particle size smaller than 50μ to a primary calcination treatment at a temperature of 900° to 1200° C. in an inert gas atmosphere or reducing gas atmosphere without using a binder, to thereby form a calcination product, pulverizing and classifying said calcination product to prepare an intermediate iron powder having a particle size of 50 to 200μ, if necessary, reducing the intermediate iron powder in a reducing atmosphere and washing the intermediate iron powder with at least one member selected from the group consisting of water, a solution containing surface active agents and organic solvents, and subjecting the intermediate iron powder to an oxidizing calcination treatment at a temperature of 280° to 390° C. said process being free of the application of a coating to said powder particles.
Claim 2
Dependent Claim
153 words
A process for the preparation of iron powder developer carriers for electrophotography, which comprises the steps of subjecting a starting iron powder pulverized to a particle size smaller than 50μ to a primary calcination treatment at a temperature of 900° to 1200° C. in an inert gas atmosphere or reducing gas atmosphere without using a binder, to thereby form a calcination product, pulverizing and classifying said calcination product to prepare an intermediate iron powder having a particle size of 50 to 200μ, if necessary, reducing the intermediate iron powder in a reducing atmosphere and washing the intermediate iron powder with at least one member selected from the group consisting of water, a solution containing surface active agents and organic solvents, and subjecting the intermediate iron powder to an oxidizing calcination treatment at a temperature of 280° to 390° C. said process being free of the application of a coating to said powder particles.
Claim 3
Dependent Claim
48 words
A process for the preparation of iron powder developer carriers for electrophotography according to claim 1 wherein the product obtained by said oxidizing calcination treatment is washed with at least one member selected from the group consisting of water, a solution containing surface active agents and organic solvents.
Claim 4
Dependent Claim
24 words
An iron powder developer carrier for electrophotography prepared by the process of claim 1, wherein said carrier is not provided with a resin coating.
Claim 5
Dependent Claim
64 words
A developer for electrophotography comprising the iron powder developer carrier of claim 3 and a toner, said developer carrier having a particle size of 50 to 200μ, an apparent density of 1.5 to 2.5 g/ cm 3 and a specific surface area of 0.01 to 0.3 m 2 /g, wherein said carrier is free of resin coating except that transferred thereon from said toner.
Claim 6
Dependent Claim
37 words
A developer for electrophotography as set forth in claim 4, wherein the toner is present in the developer in an amount of 2 to 10 parts per 100 parts of the developer carrier present in the developer.
Claim 7
Dependent Claim
99 words
An image-forming method comprising developing an electrostatic latent image formed on a photoconductive photosensitive material by using a developer comprising a developer carrier and a toner, if necessary under application of a bias voltage, said developer carrier being the iron powder developer carrier of claim 3 a particle size of 50 to 200μ, an apparent density of 1.5 to 2.5 g/cm 3 and a specific surface area of 0.01 to 0.3 m 2 /g, to thereby form a visible image, and heat-fixing said visible image directly as it is or after it has been transferred onto a transfer sheet.
Claim 8
Dependent Claim
39 words
The iron powder developer carrier for electrophotography of claim 3 having a particle size of 50 to 200μ, an apparent density of 1.5 to 2.5 g/cm 3 and a specific surface area of 0.01 to 0.3 m 2 /g.
Claim 9
Dependent Claim
24 words
An iron powder developer carrier for electrophotography as set forth in claim 7, wherein particles of the iron powder developer carrier are porous particles.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-05-20 | 1988-11-19 | 1989-05-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-05-20 | 1992-11-19 | 1993-05-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-05-20 | 1996-11-19 | 1997-05-21 | $7700.00 | Window Closed / Lapsed |