Patent US4379824A successfully refreshed from Google Patents.
US4379824A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Developer compositions having layer of a pigment on the surface thereof
Assignee: 3M Co
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Filing: 1981-04-17
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Granted: 1983-04-12
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Expires: 2001-04-17
Abstract
Abstract A developer composition capable of developing electrostatic images on dielectric surfaces is disclosed. The composition has an electrical conductivity of at least 10 -6 ohm -1 centimeter -1 and utilizes a small dimension powdered material as a coating on the essentially smooth surface of individual spheroids of a toner. The composition reduces background coloration on finished copies and eliminates the need to bias the magnetic development roll.
Inventors
- 👤 Stanley B. Collins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 13:33
CPC Classifications
G; G03; G03G; G03G9/00; G03G9/08; G03G9/0821; G03G9/0823; G03G9/0825
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
137 words
A dry composition capable of being attracted to electrostatic image areas on a dielectric surface, said composition having a static electrical conductivity of at least 10 -6 ohm -1 centimeter -1 wherein said composition comprises a plurality of discrete spheroids each having an essentially smooth surface and each comprising a thermoplastic organic resin with a magnetically responsive material distributed therein, and from about 1 to 12 μg per square centimeter of surface area of said spheroids of a coating of a first pigment on said smooth surface wherein said first pigment comprises particles each having an arithmetic mean particle size of at least 0.02 micron, a dibutyl phthalate absorption value of at least 150 cubic centimeters per 100 grams of said pigment, and a static electrical conductivity of at least 10 -8 ohm -1 centimeter -1 .
Claim 2
Dependent Claim
137 words
A dry composition capable of being attracted to electrostatic image areas on a dielectric surface, said composition having a static electrical conductivity of at least 10 -6 ohm -1 centimeter -1 wherein said composition comprises a plurality of discrete spheroids each having an essentially smooth surface and each comprising a thermoplastic organic resin with a magnetically responsive material distributed therein, and from about 1 to 12 μg per square centimeter of surface area of said spheroids of a coating of a first pigment on said smooth surface wherein said first pigment comprises particles each having an arithmetic mean particle size of at least 0.02 micron, a dibutyl phthalate absorption value of at least 150 cubic centimeters per 100 grams of said pigment, and a static electrical conductivity of at least 10 -8 ohm -1 centimeter -1 .
Claim 3
Dependent Claim
22 words
A composition according to claim 1 comprising from about 1.5 to 3.5 μg per square centimeter of surface area of said spheroids.
Claim 4
Dependent Claim
13 words
A composition according to claim 1 wherein said first pigment comprises carbon black.
Claim 5
Dependent Claim
56 words
A composition according to claims 1, 2 or 3 wherein said first pigment has an arithmetic mean particle size of at least 0.03 micron, a dibutyl phthalate absorption value of at least 180 cubic centimeters per 100 grams of said pigment, and a static electrical conductivity of at least 10 -4 ohm -1 centimeter -1 .
Claim 6
Dependent Claim
32 words
A composition according to claim 3 wherein said spheroids each further include a magnetically non-responsive second pigment having a static electrical conductivity of at least 10 -8 ohm -1 centimeter -1 .
Claim 7
Dependent Claim
22 words
A composition according to claim 5 wherein said second pigment is embedded in said spheroids as a layer near said smooth surface.
Claim 8
Dependent Claim
13 words
A composition according to claim 6 wherein said second pigment is carbon black.
Claim 9
Dependent Claim
13 words
A composition according to claim 1 wherein said magnetically responsive material comprises magnetite.
Claim 10
Dependent Claim
138 words
A dry composition capable of being attracted to electrostatic image areas on a dielectric surface, said composition having a static electrical conductivity of at least 10 -6 ohm -1 centimeter -1 wherein said composition comprises a plurality of discrete spheroids each having an essentially smooth surface and each comprising a thermoplastic organic resin with a first magnetically responsive material and a magnetically non-responsive pigment having a static electrical conductivity of at least 10 -4 ohm -1 centimeter -1 distributed therein, and from about 15 to 70 μg per square centimeter of surface area of said spheroids of a coating of a second magnetically responsive material having a needle-like structure, a static electrical conductivity of at least 10 -7 ohm -1 cm -1 , and an arithmetic mean maximum dimension of at least 0.2 micron on said smooth surface.
Claim 11
Dependent Claim
138 words
A dry composition capable of being attracted to electrostatic image areas on a dielectric surface, said composition having a static electrical conductivity of at least 10 -6 ohm -1 centimeter -1 wherein said composition comprises a plurality of discrete spheroids each having an essentially smooth surface and each comprising a thermoplastic organic resin with a first magnetically responsive material and a magnetically non-responsive pigment having a static electrical conductivity of at least 10 -4 ohm -1 centimeter -1 distributed therein, and from about 15 to 70 μg per square centimeter of surface area of said spheroids of a coating of a second magnetically responsive material having a needle-like structure, a static electrical conductivity of at least 10 -7 ohm -1 cm -1 , and an arithmetic mean maximum dimension of at least 0.2 micron on said smooth surface.
Claim 12
Dependent Claim
22 words
A composition according to claim 9 comprising from about 20 to 40 μg of said coating per square centimeter of said spheroids.
Claim 13
Dependent Claim
17 words
A composition according to claim 9 wherein said first and second magnetically responsive materials individually comprise magnetite.
Claim 14
Dependent Claim
28 words
A composition according to claims 9, 10, or 11 wherein said electrically conductive, magnetically non-responsive pigment is embedded in said spheroids as a layer near said smooth surface.
Claim 15
Dependent Claim
16 words
A composition according to claim 12 wherein said electrically conductive, magnetically non-responsive pigment comprises carbon black.
Claim 16
Dependent Claim
24 words
A composition according to claim 10 wherein said second magnetically responsive material has an arithmetic mean maximum particle size of at least 0.4 micron.
Claim 17
Dependent Claim
15 words
A composition according to claim 14 wherein said second magnetically responsive material is acicular magnetite.
Claim 18
Dependent Claim
15 words
A composition according to claims 1 or 9 wherein said spheroids further include a surfactant.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-04-11 | 1986-10-11 | 1987-04-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-04-11 | 1990-10-11 | 1991-04-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-04-11 | 1994-10-11 | 1995-04-12 | $7700.00 | Window Closed / Lapsed |