US3673126A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Continuous process for making expandable thermoplastic resin compositions
Assignee: Dow Chemical Co
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Filing: 1967-11-13
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Granted: 1972-06-27
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Expires: 1987-11-13
Abstract
Abstract A continuous process for the production of expandable thermoplastic polymer compositions obviating the use of a pressure vessel for polymerization is described. Freshly polymerized, devolatilized polymeric melt and a blowing agent are mixed prior to complete cooling of the melt and extruding the mixture at a continuous rate equal to the rate at which the mixture is supplied, to obtain greatly improved product properties.
Inventors
- 👤 William D Carmody
- 👤 Charles J Thompson
- 👤 George J Butzler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 04:51
CPC Classifications
B; B29; B29C; B29C44/00; B29C44/34; B29C44/36; B29C44/46; B29C44/461; B29C44/50; B29C44/505; C; C08; C08J; C08J9/00; C08J9/04; C08J9/12; C08J9/14; Y; Y10; Y10S; Y10S521/00; Y10S521/921
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
36 words
continuously extruding the mixture comprising the heat-plastified thermoplastic polymer and the volatile organic foaming agent compound at a rate equivalent to that at which the devolatilized polymeric melt and volatile organic foaming agent compound are supplied.
Claim 2
Dependent Claim
11 words
The process of claim 1 wherein the thermoplastic polymer is polystyrene.
Claim 3
Dependent Claim
19 words
The method of claim 1 including the step of forming the rigid extruded material into a plurality of particles.
References Cited (Backward Citations)
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US2676927A
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US2727884A
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US3287286A
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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) | 1975-06-27 | 1975-12-27 | 1976-06-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-27 | 1979-12-27 | 1980-06-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-27 | 1983-12-27 | 1984-06-27 | $7700.00 | Window Closed / Lapsed |