US3640915A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Production of foamed polyethylene
Assignee: Expanded Rubber & Plastics Ltd
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Filing: 1968-10-17
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Granted: 1972-02-08
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Expires: 1988-10-17
Abstract
Abstract THE PRESENT INVENTION RELATES TO A PROCESS FOR PRODUCING EXPANDED POLYETHYLENE HAVING A DENSITY OF FROM 1 TO 5 LBS./FT.3 COMPRISING RAISING THE MELTING POINT OF ETHYLENE POLYMER BY SUBJECTING THE POLYMER TO A CROSS-LINKING TREATMENT EQUIVALENT TO THAT PRODUCED BY AN IRRADIATION DOSE OF BETWEEN 2 AND 6 MEGARADS AND THEREAFTER HEATING THE CROSS-LINKED POLYMER TO A TEMPERATURE ABOVE THE SOFTENING TEMPERATURE IN ATMOSPHERE OF NITROGEN AT A PRESSURE OF 2,000 TO 12,000 LBS. PER SQUARE INCH TO IMPREGNATE THE POLYMER WITH NITROGEN AND EXPANDING THE NITROGEN-IMPREGNATED POLYMER BY RELEASING TH PRESSURE THEREON.
Inventors
- 👤 Alfred Cooper
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 15:09
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/04; C08J9/12; C08J9/122; C08J2323/00; C08J2323/02; C08J2323/04; C08J2323/06; Y; Y10; Y10S; Y10S264/00; Y10S264/18; Y10S521/00; Y10S521/915
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) | 1975-02-07 | 1975-08-09 | 1976-02-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-07 | 1979-08-09 | 1980-02-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-07 | 1983-08-09 | 1984-02-08 | $7700.00 | Window Closed / Lapsed |