US4478925A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of preparing carrier particles for electrographic magnetic brush dry development
Assignee: Eastman Kodak Co
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Filing: 1983-03-03
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Granted: 1984-10-23
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Expires: 2003-03-03
Abstract
Abstract Magnetic carrier particles for electrophotographic developers are coated with a thermoplastic resin by agitating a dry mixture of carrier particles and resin particles in a magnetic field. Thereafter, the mixture is heated to bond the resin to the carrier particles, which then need no further treatment to improve their conductivity prior to use in an electrophotographic developer.
Inventors
- 👤 Edward T. Miskinis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 18:06
CPC Classifications
G; G03; G03G; G03G9/00; G03G9/08; G03G9/10; G03G9/113; G03G9/1132; G03G9/1133; G03G9/1134; G03G9/107; G03G9/1075
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
58 words
A method of preparation of resin-coated ferromagnetic carrier particles for electrographic development which comprises agitating a dry mixture of ferromagnetic carrier particles and resin particles in the presence of a magnetic field and thereafter heating the mixture to a temperature and for a time sufficient to form a discontinuous bonded coating of the resin on the ferromagnetic particles.
Claim 2
Independent Claim
58 words
A method of preparation of resin-coated ferromagnetic carrier particles for electrographic development which comprises agitating a dry mixture of ferromagnetic carrier particles and resin particles in the presence of a magnetic field and thereafter heating the mixture to a temperature and for a time sufficient to form a discontinuous bonded coating of the resin on the ferromagnetic particles.
Claim 3
Dependent Claim
50 words
A method according to claim 1 wherein the ferromagnetic particles are iron or steel particles having an average diameter 40 to 500 microns, the resin is a thermoplastic fluorocarbon polymer and the resin particles are smaller than the carrier particles and have a particle size from 1 to 30 microns.
Claim 4
Dependent Claim
25 words
A method according to claim 2, wherein the magnetic field is formed by a magnetic brush and has a strength of at least 300 gauss.
Claim 5
Dependent Claim
51 words
A method according to claim 3, wherein the carrier particles and resin particles are first dry-mixed with thorough agitation in the absence of a magnetic field before being dry-mixed in the presence of a magnetic field and thereafter the dry-mixed product is heated to bond the resin to the carrier particles.
References Cited (Backward Citations)
US4081571A
Cited
US4024295A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-10-23 | 1988-04-23 | 1988-10-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-10-23 | 1992-04-23 | 1992-10-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-10-23 | 1996-04-23 | 1996-10-23 | $7700.00 | Window Closed / Lapsed |