US4124735A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic glass carrier materials
Assignee: Xerox Corp
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Filing: 1976-12-02
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Granted: 1978-11-07
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Expires: 1996-12-02
Abstract
Abstract Electrostatographic carrier materials having low bulk densities and high magnetic permeabilities are obtained by providing an alumino-boro-silicate glass particle containing from between about 10 to about 15 molar percent Fe 2 O 3 in which superparamagnetic ferrite crystallites having an average particle size of up to about 500A have been precipitated by heat treatment. The magnetic behavior of the glass carrier particles which is dependent on the number present and size of the ferrite crystallites can be closely controlled by heat treatment at temperatures in the range of between about 600° C and 800° C. When mixed with toner particles, these magnetic glass carrier materials experience significantly reduced toner impaction levels.
Inventors
- 👤 Michael P. O'Horo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 08:15
CPC Classifications
C; C03; C03C; C03C10/00; C03C10/0081; C03C12/00; G; G03; G03G; G03G9/00; G03G9/08; G03G9/10; G03G9/103; G03G9/107; G03G9/1075; G03G9/108; H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/12; H01F1/34; H01F1/36; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/29; Y10T428/2982; Y10T428/2991; Y10T428/2993; Y10T428/2996; Y10T428/2998
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
123 words
A low density, magnetic, composite electrostatographic carrier particle consisting essentially of a borosilicate glass further containing about 20 molar percent CaO, about 10 molar percent Al 2 O 3 , and from between about 10 to about 15 molar percent Fe 2 O 3 in which superparamagnetic Fe 3 O 4 ferrite crystallites having an average particle size of up to about 500 A have been precipitated by heat treatment of said glass at temperatures in the range of between about 600° C. and about 800° C. for up to about 24 hours, wherein said carrier particle has a resistivity on the order of about 10 6 to about 10 12 ohm/cm and displays soft magnetic properties with a lack of hysteresis behavior.
Claim 2
Dependent Claim
123 words
A low density, magnetic, composite electrostatographic carrier particle consisting essentially of a borosilicate glass further containing about 20 molar percent CaO, about 10 molar percent Al 2 O 3 , and from between about 10 to about 15 molar percent Fe 2 O 3 in which superparamagnetic Fe 3 O 4 ferrite crystallites having an average particle size of up to about 500 A have been precipitated by heat treatment of said glass at temperatures in the range of between about 600° C. and about 800° C. for up to about 24 hours, wherein said carrier particle has a resistivity on the order of about 10 6 to about 10 12 ohm/cm and displays soft magnetic properties with a lack of hysteresis behavior.
Claim 3
Dependent Claim
30 words
A low density, magnetic, composite electrostatographic carrier particle in accordance with claim 1 wherein said carrier particle has a conductivity of greater than about 10 -10 ohm-cm. at 25° C.
Claim 4
Dependent Claim
51 words
A low density, magnetic, composite electrostatographic carrier particle in accordance with claim 1 wherein said ferrite crystallites have been precipitated by heat treatment at a temperature of about 600° C. for up to about 24 hours followed by heat treatment at a temperature of about 700° C. for about 1 hour.
Claim 5
Dependent Claim
32 words
A low density, magnetic, composite electrostatographic carrier particle in accordance with claim 1 wherein said carrier particle has an average particle size of from between about 10 microns and about 850 microns.
Claim 6
Dependent Claim
32 words
A low density, magnetic, composite electrostatographic carrier particle in accordance with claim 1 wherein said carrier particle has an average bulk density of between about 2.5 and about 2.8 grams/cm 3 .
Claim 7
Dependent Claim
25 words
A low density, magnetic, composite electrostatographic carrier particle in accordance with claim 1 wherein said carrier particle has an overcoating of an insulating resinous material.
Claim 8
Dependent Claim
140 words
A low density, magnetic composite electrostatographic carrier particle comprising alumino-boro-silicate glass containing about 40 molar percent SiO 2 , about 30 molar percent B 2 O 3 , about 20 molar percent CaO, and about 10 molar percent Al 2 O 3 , said alumino-boro-silicate glass also containing from between about 10 to about 15 molar percent Fe 2 O 3 in which superparamagnetic Fe 3 O 4 ferrite crystallites having an average particle size of up to about 500 A have been precipitated by heat treatment of said glass at temperatures in the range of between about 600° C. and about 800° C. for up to about 24 hours, wherein said carrier particle has a resistivity on the order of about 10 6 to about 10 12 ohm/cm and displays soft magnetic properties with a lack of hysteresis behavior.
Claim 9
Dependent Claim
140 words
A low density, magnetic composite electrostatographic carrier particle comprising alumino-boro-silicate glass containing about 40 molar percent SiO 2 , about 30 molar percent B 2 O 3 , about 20 molar percent CaO, and about 10 molar percent Al 2 O 3 , said alumino-boro-silicate glass also containing from between about 10 to about 15 molar percent Fe 2 O 3 in which superparamagnetic Fe 3 O 4 ferrite crystallites having an average particle size of up to about 500 A have been precipitated by heat treatment of said glass at temperatures in the range of between about 600° C. and about 800° C. for up to about 24 hours, wherein said carrier particle has a resistivity on the order of about 10 6 to about 10 12 ohm/cm and displays soft magnetic properties with a lack of hysteresis behavior.
Claim 10
Dependent Claim
30 words
A low density, magnetic, composite electrostatographic carrier particle in accordance with claim 7 wherein said carrier particle has a conductivity of greater than about 10 -10 ohm-cm. at 25° C.
Claim 11
Dependent Claim
51 words
A low density, magnetic, composite electrostatographic carrier particle in accordance with claim 7 wherein said ferrite crystallites have been precipitated by heat treatment at a temperature of about 600° C. for up to about 24 hours followed by heat treatment at a temperature of about 700° C. for about 1 hour.
Claim 12
Dependent Claim
32 words
A low density, magnetic, composite electrostatographic carrier particle in accordance with claim 7 wherein said carrier particle has an average particle size of from between about 10 microns and about 850 microns.
Claim 13
Dependent Claim
32 words
A low density, magnetic, composite electrostatographic carrier particle in accordance with claim 7 wherein said carrier particle has an average bulk density of between about 2.5 and about 2.8 grams/cm 3 .
Claim 14
Dependent Claim
25 words
A low density, magnetic, composite electrostatographic carrier particle in accordance with claim 7 wherein said carrier particle has an overcoating of an insulating resinous material.
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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) | 1981-11-06 | 1982-05-08 | 1982-11-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-11-06 | 1986-05-08 | 1986-11-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-11-06 | 1990-05-08 | 1990-11-07 | $7700.00 | Window Closed / Lapsed |