US4128674A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of making pigmented phosphors
Assignee: GTE Sylvania Inc
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Filing: 1976-03-31
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Granted: 1978-12-05
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Expires: 1996-03-31
Abstract
Abstract A pigmented phosphor comprises a core of a phosphor particle having a light modifying layer thereon. The light modifying layer is comprised of a co-precipitated mixture of silica or pyrophosphate and a pigment which modifies the light output of the energized phosphor. The phosphor is coated by first preparing an unique pigment stock suspension containing the pigment, water, and a polyacrylamide dispersant. The stock solution is then diluted and phosphor particles are added thereto and the mixture is vigorously stirred. The pH of the mixture can be adjusted to about 5 by the addition of acetic acid and then a small amount of positively charged colloidal silica or pyrophosphate is added. After mixing, the pH is raised to about 9 by the addition of a base or a salt which causes a gel to form and the silica or pyrophosphate and the pigment to co-precipitate out upon the phosphor particles.
Inventors
- 👤 Robert A. Hedler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 07:14
CPC Classifications
C; C09; C09K; C09K11/00; C09K11/02; Y; Y10; Y10T; Y10T428/00; Y10T428/29; Y10T428/2982; Y10T428/2991; Y10T428/2993; Y10T428/2998
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
102 words
A method of making free-flowing, pigmented phosphors comprising the steps of: diluting with water a 20% pigment stock suspension containing a polyacrylamide; adding phosphor particles and agitating vigorously; adjusting the pH to about 5.0 by adding a 10% acetic acid solution; adding a small amount of a positively charged colloidal silica with constant stirring; adding a base to raise the pH to about 9; stirring for a suitable time to allow said silica and said pigment to co-precipitate upon said phosphor particles; and removing the remaining liquid and drying said phosphor particles; and removing the remaining liquid and drying said phosphor particles.
Claim 2
Independent Claim
102 words
A method of making free-flowing, pigmented phosphors comprising the steps of: diluting with water a 20% pigment stock suspension containing a polyacrylamide; adding phosphor particles and agitating vigorously; adjusting the pH to about 5.0 by adding a 10% acetic acid solution; adding a small amount of a positively charged colloidal silica with constant stirring; adding a base to raise the pH to about 9; stirring for a suitable time to allow said silica and said pigment to co-precipitate upon said phosphor particles; and removing the remaining liquid and drying said phosphor particles; and removing the remaining liquid and drying said phosphor particles.
Claim 3
Dependent Claim
14 words
The method of claim 1 wherein said constant stirring occurs for about 10 minutes.
Claim 4
Dependent Claim
13 words
The method of claim 2 wherein said suitable time is about 10 minutes.
Claim 5
Dependent Claim
11 words
The method of claim 3 wherein said base is ammonium hydroxide.
Claim 6
Dependent Claim
13 words
The method of claim 4 wherein said ammonium hydroxide is a 3% solution.
Claim 7
Dependent Claim
14 words
The method of claim 5 wherein said phosphor is dried at about 130° C.
Claim 8
Independent Claim
76 words
A method of making free-flowing pigmented phosphors comprising the steps of: diluting with water a 20% pigment stock suspension containing a polyacrylamide; adding phosphor particles and agitating vigorously; adjusting the pH to about 5; adding a pyrophosphate; adding a salt which will form an insoluble pyrophosphate to cause precipitation; stirring for a suitable time to allow said pyrophosphate and said pigment to co-precipitate upon said phosphor particles; and removing the remaing liquid and drying said phosphor.
Claim 9
Independent Claim
76 words
A method of making free-flowing pigmented phosphors comprising the steps of: diluting with water a 20% pigment stock suspension containing a polyacrylamide; adding phosphor particles and agitating vigorously; adjusting the pH to about 5; adding a pyrophosphate; adding a salt which will form an insoluble pyrophosphate to cause precipitation; stirring for a suitable time to allow said pyrophosphate and said pigment to co-precipitate upon said phosphor particles; and removing the remaing liquid and drying said phosphor.
Claim 10
Dependent Claim
11 words
The method of claim 7 wherein said salt is magnesium chloride.
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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) | 1981-12-04 | 1982-06-05 | 1982-12-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-12-04 | 1986-06-05 | 1986-12-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-12-04 | 1990-06-05 | 1990-12-05 | $7700.00 | Window Closed / Lapsed |