US4264698A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Developer for electrostatic photography and process for preparation thereof
Assignee: Kyocera Mita Industrial Co Ltd
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Filing: 1976-10-15
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Granted: 1981-04-28
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Expires: 1996-10-15
Abstract
Abstract A developer for electrostatic photography consisting essentially of a dry blend of (A) substantially spherical fixing magneto-sensitive particles of a composition comprising a binder medium and a fine powder of a magnetic material dispersed in the binder medium, the substantially spherical particles (A) have on their surfaces fine convexities and concavities formed by spraying a dispersion of the composition into a drying atmosphere and have a particle size of 2 to 44 microns, and (B) flowability- and electric resistance-controlling fine particles having a volume resistivity not higher than 10 12 ω-cm and a particle size not larger than 1/10 of the particle size of the substantially spherical particles (A). The fine particles (B) are distributed predominantly on the surface portion of said spherical particles (A). The mixing weight ratio of (A):(B) is in the range of from 1000:1 to 50:1.
Inventors
- 👤 Hiroshi Takayama
- 👤 Tatsuo Aizawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:32
CPC Classifications
G; G03; G03G; G03G9/00; G03G9/08; G03G9/083; G03G9/0837; G03G9/09; G03G9/0902; G03G9/0904; G03G9/10; Y; Y10; Y10T; Y10T428/00; Y10T428/29; Y10T428/2982; Y10T428/2991; Y10T428/2998
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
208 words
A developer for electrostatic photography consisting essentially of a dry blend of (A) substantially spherical fixing magneto-sensitive particles of a composition consisting essentially of 40 to 60% by weight of a fine powder of a magnetic material, 30 to 60% by weight of a binder medium composed of a resin, rubber or wax having an adhesiveness under application of heat or pressure and 1 to 10% by weight of carbon black, said fine powder of the magnetic material being dispersed in said binder medium, said substantially spherical particles (A) having on the surfaces thereof fine convexities and concavities formed by spraying a dispersion of said composition into a drying atmosphere and having a particle size of 2 to 44 microns, and (B) flowability- and electric resistance-controlling fine particles having a volume resistivity not higher than 10 12 Ω-cm and a particle size not larger than 1/10 of the particle size of the substantially spherical particles (A), said substantially spherical particles (A) being dry-blended with said fine particles (B) at a mixing weight ratio (A):(B) in the range of from 2000:1 to 100:1, said fine particles (B) being distributed predominantly on and adhering to the surface portion of said spherical particles (A) without being embedded by the dry blending.
Claim 2
Dependent Claim
208 words
A developer for electrostatic photography consisting essentially of a dry blend of (A) substantially spherical fixing magneto-sensitive particles of a composition consisting essentially of 40 to 60% by weight of a fine powder of a magnetic material, 30 to 60% by weight of a binder medium composed of a resin, rubber or wax having an adhesiveness under application of heat or pressure and 1 to 10% by weight of carbon black, said fine powder of the magnetic material being dispersed in said binder medium, said substantially spherical particles (A) having on the surfaces thereof fine convexities and concavities formed by spraying a dispersion of said composition into a drying atmosphere and having a particle size of 2 to 44 microns, and (B) flowability- and electric resistance-controlling fine particles having a volume resistivity not higher than 10 12 Ω-cm and a particle size not larger than 1/10 of the particle size of the substantially spherical particles (A), said substantially spherical particles (A) being dry-blended with said fine particles (B) at a mixing weight ratio (A):(B) in the range of from 2000:1 to 100:1, said fine particles (B) being distributed predominantly on and adhering to the surface portion of said spherical particles (A) without being embedded by the dry blending.
Claim 3
Dependent Claim
30 words
A developer as set forth in claim 1 wherein the fine powder of the magnetic material is a powder of triiron tetroxide having a particle size smaller than 500 mμ.
Claim 4
Dependent Claim
15 words
A developer as set forth in claim 1 wherein the resin is an epoxy resin.
Claim 5
Dependent Claim
24 words
A developer as set forth in claim 1 wherein the substantially spherical fixing magneto-sensitive particles (A) have an oil absorption of 25 to 40.
Claim 6
Dependent Claim
75 words
A developer as set forth in claim 1 wherein the substantially spherical fixing magneto-sensitive particles (A) are formed by dissolving a binder medium composed of a resin, rubber or wax in an easily volatile organic solvent so that the binder medium concentration is not higher than 30% by weight, dispersing a fine powder of a magnetic material in the solution and spraying the resulting slurry into a drying atmosphere to thereby effect drying and granulation.
Claim 7
Dependent Claim
21 words
A developer as set forth in claim 1 wherein the flowability- and electric resistance-controlling fine particles are composed of carbon black.
References Cited (Backward Citations)
US3196032A
Cited
US3345294A
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US3639245A
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US3627682A
Cited
US3925219A
Cited
US4082681A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-04-27 | 1984-10-27 | 1985-04-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-04-27 | 1988-10-27 | 1989-04-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-04-27 | 1992-10-27 | 1993-04-28 | $7700.00 | Window Closed / Lapsed |