US3795729A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the production of foamed polystyrene materials
Assignee: Denka Co Ltd
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Filing: 1971-11-29
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Granted: 1974-03-05
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Expires: 1991-11-29
Abstract
Abstract A POLYSTYRENE RESIN CONTAINING A FOAMING AGENT IS EXTRUDED THROUGH A DIE WITH A SIMPLE APERTURE WHICH WILL NOT CAUSE IRREGULAR RESIN FLOW SUCH THAT RESIN FOAMS TO A CROSS SECTION AREA AT MOST 6.5 TIMES THAT OF THE DIE APERTURE, THE RESULTING FOAMED MATERIAL IS FORCED THROUGH A SIZING GATE OF A CROSS SECTINAL AREA 1.5 TO 6.5 TIMES THAT OF THE DIE APERTURE WHILE THE FOAMINE AGENT IS STILL ACTIVELY DECOMPOSING, AND THE FOAMED MATERIAL THUS SIZED IS THEN COOLED AND SET.
Inventors
- 👤 H Asakura
- 👤 M Kusaka
- 👤 K Takano
- 👤 Y Arai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 23:19
CPC Classifications
B; B29; B29C; B29C44/00; B29C44/34; B29C44/36; B29C44/46; B29C44/468; Y; Y10; Y10S; Y10S264/00; Y10S264/66; Y10S425/00; Y10S425/812
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-03-04 | 1977-09-03 | 1978-03-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-04 | 1981-09-03 | 1982-03-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-04 | 1985-09-03 | 1986-03-05 | $7700.00 | Window Closed / Lapsed |