US3723362A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low density polystyrene pearls and methods of making them
Assignee: Compagnie de Saint Gobain SA
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Filing: 1968-10-21
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Granted: 1973-03-27
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Expires: 1988-10-21
Abstract
Abstract POLYSTYRENE PEARLS ARE MADE BY INSUFFLATING POLYSTYRENE PARTICLES CONTAINING EXPANSION AGENT BY HOT AIR FOLLOWED BY BRIEF INSUFFLATION BY SUPERHEATED STREAM. A FURTHER ADVANTAGE CAN BE OBTAINED BY SUBJECTING THESE EXPANDED PEARLS TO HEAT TREATMENT IN AN AUTOCLAVE. THE SUCCESSIVE TREATMENTS BY HOT AIR AND STREAM ARE AT ATMOSPHERIC PRESSURE AND AT TEMPERATURE WHICH ARE ADEQUATE TO SOFTEN THE POLYSTYRENE AND ACTIVATE THE EXPANSION AGENT. PRODUCTS CAN BE PRODUCED WHICH HAVE ANY CHOSEN DENSITY FROM 2.5 KG./M3. UPWARD. PRODUCTS OF LOWEST DENSITIES ARE UNIQUE.
Inventors
- 👤 Jean Battigelli
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:19
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/22; C08J9/228; B; B29; B29C; B29C44/00; B29C44/34; B29C44/3461; C08J2325/00; Y; Y10; Y10S; Y10S264/00; Y10S264/09
Claims Analysis
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References Cited (Backward Citations)
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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) | 1976-03-26 | 1976-09-25 | 1977-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-26 | 1980-09-25 | 1981-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-26 | 1984-09-25 | 1985-03-27 | $7700.00 | Window Closed / Lapsed |