US3718594A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of preparing magnetically responsive carrier particles
Assignee: Eastman Kodak Co
•
Filing: 1970-11-30
•
Granted: 1973-02-27
•
Expires: 1990-11-30
Abstract
Abstract Ferromagnetic carrier particles having uniform surface and triboelectric properties can be prepared by treatment of commercial iron powders in an aqueous acid solution, followed by removal of acid, rinsing and controlled drying to induce or exclude oxidation. The resultant particles can subsequently be overcoated with a thin, uniform, continuous film of a nonferrous material such as metal or a resinous material. These carrier particles are useful for applying electroscopic toner material to electrostatic latent images.
Inventors
- 👤 H Miller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:10
CPC Classifications
G; G03; G03G; G03G9/00; G03G9/08; G03G9/10; G03G9/113; G03G9/1131; G03G9/107; G03G9/1075; G03G9/1132; G03G9/1139; Y; Y10; Y10S; Y10S428/00; Y10S428/922; Y10S428/9265; Y10S428/928; Y10T; Y10T428/00; Y10T428/12; Y10T428/12181
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
23 words
The process as described in claim 1 wherein up to about 2 percent by weight of the iron is dissolved from said particles.
Claim 2
Dependent Claim
22 words
A process as described in claim 1 wherein the antioxidant is selected from the group consisting of hydrazine sulfate and sodium nitrite.
Claim 3
Dependent Claim
33 words
A process as described in claim 1 including the additional step of rinsing the wet powder with a water-miscible organic solvent to remove residual water from the iron prior to drying the powder.
Claim 4
Dependent Claim
25 words
A process as described in claim 4 wherein the water-miscible organic solvent is selected from the group consisting of acetone and a lower alkyl alcohol.
Claim 5
Dependent Claim
175 words
A process for preparing a magnetically responsive developer composition for use in developing electrostatic charge patterns comprising the steps of dispersing iron powder in a dilute aqueous mineral acid bath having a concentration of about 1N to about 3N, agitating the powder while in the bath, separating the powder from the bath, rinsing the powder with water containing an antioxidant to inhibit oxidation of the iron, drying the powder in a substantially oxygen-free atmosphere to form iron particles having substantially no oxide on the surface thereof and having an electrical resistance of less than about 50 ohms, overcoating the individual iron particles with a thin, continuous layer of an electrically conducting nonferrous metal to form an electrically conducting, magnetically responsive carrier particle having an electrical resistance of less than about 10 ohms, and subsequently mixing from about 90 to about 99 percent by weight of the resultant carrier particles with from about 10 to about 1 percent by weight of an electroscopic toner material having a particle size smaller than that of the carrier particles.
References Cited (Backward Citations)
US2791561A
Cited
US2809731A
Cited
US2933415A
Cited
US2941949A
Cited
US3135632A
Cited
US3189450A
Cited
US3020175A
Cited
US3282723A
Cited
US3202529A
Cited
US3489603A
Cited
US3511683A
Cited
US3607750A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-02-27 | 1976-08-28 | 1977-02-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-27 | 1980-08-28 | 1981-02-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-27 | 1984-08-28 | 1985-02-27 | $7700.00 | Window Closed / Lapsed |