Patent US2665452A successfully refreshed from Google Patents.
US2665452A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of producing transparent polystyrene sheets
Assignee: Cast Optics Corp
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Filing: 1951-08-01
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Granted: 1954-01-12
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Expires: 1971-08-01
Abstract
No abstract record available.
Inventors
- 👤 John O Beattie
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 19:47
CPC Classifications
B; B29; B29C; B29C39/00; B29C39/003; B29C39/006; C; C08; C08F; C08F12/00; C08F12/02; C08F12/04; C08F12/06; C08F12/08
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
195 words
THE PROCESS OF PRODUCING CRAZE AND BUBBLE FREE MOLDED TRANSPARENT SHEETS OF POLYMERIZED STYRENE COMPRISING THE STEPS OF ADDING A PARTING AGENT TO STYRENE OF WATERY THIN CONSISTENCY, THICKENING THE MIXTURE BY BOILING AT A TEMPERATURE OF ABOUT 146* C. FOR A PERIOD OF ABOUT 10 MINUTES, ALLOWING THE MIXTURE TO COOL TO ROOM TEMPERATURE, CARRYING OUT THE HEAT POLYMERIZATION OF THE THICKENED MIXTURE BY ADMIXING THEREWITH ISOPROPYL PERCARBONATE IN THE AMOUNT OF FROM .125% TO 5% BY WEIGHT OF THE THICKENED MIXTURE, PLACING THE MIXTURE IN A SHEET FORMING MOLD, CURING THE MIXTURE IN THE MOLD BY SUBJECTING THE MOLD TO LOW, INTERMEDIATE, AND HIGH TEMPERATURE STAGES FOR PRESELECTED PERIODS OF TIME, WHERE IN THE LOW TEMPERATURES STAGE THE MOLD IS MAINTAINED AT A TEMPERATURE NOT EXCEEDING 55* C. AND NOT LESS THAN 35* C. DEPENDING ON THE THICKNESS OF THE MIXTURE IN THE MOLD, FOR 15 HOURS, WHERE IN THE INTERMEDIATE STAGE THIS MOLD IS HEATED FROM THE TEMPERATURE OF THE FIRST STAGE TO A TEMPERATURE OF 80* C. OVER A PERIOD OF 12 HOURS, AND WHERE IN THE HIGH STAGE THE MOLD IS MAINTAINED AT A TEMPERATURE OF 80* C. FOR ABOUT
Claim 2
Dependent Claim
195 words
THE PROCESS OF PRODUCING CRAZE AND BUBBLE FREE MOLDED TRANSPARENT SHEETS OF POLYMERIZED STYRENE COMPRISING THE STEPS OF ADDING A PARTING AGENT TO STYRENE OF WATERY THIN CONSISTENCY, THICKENING THE MIXTURE BY BOILING AT A TEMPERATURE OF ABOUT 146* C. FOR A PERIOD OF ABOUT 10 MINUTES, ALLOWING THE MIXTURE TO COOL TO ROOM TEMPERATURE, CARRYING OUT THE HEAT POLYMERIZATION OF THE THICKENED MIXTURE BY ADMIXING THEREWITH ISOPROPYL PERCARBONATE IN THE AMOUNT OF FROM .125% TO 5% BY WEIGHT OF THE THICKENED MIXTURE, PLACING THE MIXTURE IN A SHEET FORMING MOLD, CURING THE MIXTURE IN THE MOLD BY SUBJECTING THE MOLD TO LOW, INTERMEDIATE, AND HIGH TEMPERATURE STAGES FOR PRESELECTED PERIODS OF TIME, WHERE IN THE LOW TEMPERATURES STAGE THE MOLD IS MAINTAINED AT A TEMPERATURE NOT EXCEEDING 55* C. AND NOT LESS THAN 35* C. DEPENDING ON THE THICKNESS OF THE MIXTURE IN THE MOLD, FOR 15 HOURS, WHERE IN THE INTERMEDIATE STAGE THIS MOLD IS HEATED FROM THE TEMPERATURE OF THE FIRST STAGE TO A TEMPERATURE OF 80* C. OVER A PERIOD OF 12 HOURS, AND WHERE IN THE HIGH STAGE THE MOLD IS MAINTAINED AT A TEMPERATURE OF 80* C. FOR ABOUT
Claim 3
Dependent Claim
43 words
HOURS, THEREAFTER REDUCING THE TEMPERATURE OF THE MIXTURE WITHIN THE MOLD TO AN ANNEALING TEMPERATURE OF 73* C. AND MAINTAINING SAID TEMPERATURE FOR ABOUT 30 MINUTES AND REMOVING THE MIXTURE FROM THE MOLD AT A TEMPERATURE OF FROM 71* C. TO 73* C.
Claim 4
Dependent Claim
43 words
HOURS, THEREAFTER REDUCING THE TEMPERATURE OF THE MIXTURE WITHIN THE MOLD TO AN ANNEALING TEMPERATURE OF 73* C. AND MAINTAINING SAID TEMPERATURE FOR ABOUT 30 MINUTES AND REMOVING THE MIXTURE FROM THE MOLD AT A TEMPERATURE OF FROM 71* C. TO 73* C.
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) | 1957-01-11 | 1957-07-13 | 1958-01-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1961-01-11 | 1961-07-13 | 1962-01-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1965-01-11 | 1965-07-13 | 1966-01-12 | $7700.00 | Window Closed / Lapsed |