Patent US4248953A successfully refreshed from Google Patents.
US4248953A
Expired / Lapsed
US
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Process for the production of photoconductive zinc oxide of improved electrophotographic properties, and product thereof
Assignee: Asarco LLC
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Filing: 1979-05-03
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Granted: 1981-02-03
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Expires: 1999-05-03
Abstract
Abstract Photoconductive zinc oxide characterized by having improved electrophotographic properties and particularly increased discharge speed, and produced by a process involving mixing the photoconductive zinc oxide powder to be improved with 0.01% by weight or more tellurium calculated as Te, and contacting the thus-obtained mixture with a free oxygen-containing gas while heating the mixture at elevated temperature sufficiently high and for a time sufficient to result in the zinc oxide having the improved electrophotographic properties. The heating temperature and/or heating time is held below that temperature or time at which sintering of the thus-treated product occurs.
Inventors
- 👤 Charles L. Thomas
- 👤 Sam C. Carapella
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 07:42
CPC Classifications
G; G03; G03G; G03G5/00; G03G5/02; G03G5/04; G03G5/08
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
119 words
A method for increasing the discharge speed of photoconductive zinc oxide particles by at least 10% relative to the discharge speed of the corresponding untreated zinc oxide particles comprising (a) mixing said zinc oxide particles with from about 0.01% to 0.03% tellurium calculated as Te and based on the weight of zinc oxide; and (b) contacting the resulting mixture with a free-oxygen-containing gas while heating the mixture at a temperature from about 300° C. to about 450° C. for a time sufficient to result in said at least 10% increase in said discharge speed and less than the time resulting in sintering of said mixture, said time being at least about 10 minutes and less than about 90 minutes.
Claim 2
Independent Claim
119 words
A method for increasing the discharge speed of photoconductive zinc oxide particles by at least 10% relative to the discharge speed of the corresponding untreated zinc oxide particles comprising (a) mixing said zinc oxide particles with from about 0.01% to 0.03% tellurium calculated as Te and based on the weight of zinc oxide; and (b) contacting the resulting mixture with a free-oxygen-containing gas while heating the mixture at a temperature from about 300° C. to about 450° C. for a time sufficient to result in said at least 10% increase in said discharge speed and less than the time resulting in sintering of said mixture, said time being at least about 10 minutes and less than about 90 minutes.
Claim 3
Dependent Claim
12 words
The process of claim 1 wherein the free oxygen-containing gas is air.
Claim 4
Dependent Claim
13 words
The process of claim 2 wherein the free oxygen-containing gas is oxygen-enriched air.
Claim 5
Dependent Claim
29 words
The process of claim 1 wherein at least a portion of the mixture is in a fluidized bed during the contacting of the mixture with the free oxygen-containing gas.
Claim 6
Dependent Claim
24 words
The process of claim 4 wherein the mixture is in a fluidized bed during the contacting of the mixture with the free oxygen-containing gas.
Claim 7
Dependent Claim
16 words
The process of claim 1 wherein the mixture is heated in the presence of static air.
Claim 8
Dependent Claim
13 words
The process of claim 1 wherein the alkali metal tellurate is sodium tellurate.
Claim 9
Dependent Claim
15 words
The process of claim 1 wherein the tellurium is of particle size of -100 mesh.
Claim 10
Dependent Claim
35 words
The method of claim 1 wherein said tellurium of the mixture at the outset of said contacting step is chosen from the group consisting of Te, TeO 2 , telluric acid and alkali metal tellurate.
Claim 11
Dependent Claim
123 words
A photoconductive zinc oxide characterized by having a discharge speed at least 10% greater than the discharge speed of the corresponding untreated zinc oxide particles and produced by a process comprising mixing photoconductive zinc oxide powder with from 0.01% to 0.03% by weight of tellurium, calculated as Te, and contacting the thus-obtained mixture with a free oxygen-containing gas while heating the mixture at a temperature in the range of about 300° C. to about 450° C. for a time of at least about 10 minutes and sufficient to result in the zinc oxide having the improved electrophotographic properties, at least one of the heating temperature and time being below that temperature or time at which significant sintering of the zinc oxide powder occurs.
Claim 12
Dependent Claim
123 words
A photoconductive zinc oxide characterized by having a discharge speed at least 10% greater than the discharge speed of the corresponding untreated zinc oxide particles and produced by a process comprising mixing photoconductive zinc oxide powder with from 0.01% to 0.03% by weight of tellurium, calculated as Te, and contacting the thus-obtained mixture with a free oxygen-containing gas while heating the mixture at a temperature in the range of about 300° C. to about 450° C. for a time of at least about 10 minutes and sufficient to result in the zinc oxide having the improved electrophotographic properties, at least one of the heating temperature and time being below that temperature or time at which significant sintering of the zinc oxide powder occurs.
References Cited (Backward Citations)
US3801316A
Cited
US4098609A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-02-03 | 1984-08-04 | 1985-02-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-02-03 | 1988-08-04 | 1989-02-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-02-03 | 1992-08-04 | 1993-02-03 | $7700.00 | Window Closed / Lapsed |