US4752625A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermoplastic foam molding
Assignee: Pactiv LLC
•
Filing: 1985-07-12
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Granted: 1988-06-21
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Expires: 2005-07-12
Abstract
Abstract A method for forming a molded thermoplastic foam structure comprising partially filling a mold with solvent imbibed particles of a thermoplastic resin, pressurizing said mold under conditions such as to prevent vaporization of said blowing agent during subsequent polymer melting, heating said polymer to a flowable state, releasing the mold pressure to permit foaming of the melt and expansion of the foamed polymer within the mold.
Inventors
- 👤 Wen-Pao Wu
- 👤 Charles M. Krutchen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 02:41
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/16; C08J9/18; B; B29; B29C; B29C44/00; B29C44/34; B29C44/3461; B29C44/36; B29C44/38; B29C44/44; B29C44/445; B29K; B29K2025/00; B29K2069/00; B29K2079/00; Y; Y10; Y10S; Y10S521/00; Y10S521/918
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
93 words
A molded thermoplastic polymer foam structure of solidified molten polymer wherein said polymer is a member selected from the group consisting of a blowing agent solvent imbibable polyetherimide, a linear polycarbonate and a polymer blend of polyphenylene oxide and polystyrene and wherein said polymer in its unfoamed particulate form is capable of imbibing said blowing agent selected from the group consisting of methylene chloride, chloroform, 1,1,2-trichloroethane and mixtures thereof with an amount of blowing agent sufficient to foam said polymer in a mold to a density of less than 18 lbs./ft 3 .
Claim 2
Dependent Claim
93 words
A molded thermoplastic polymer foam structure of solidified molten polymer wherein said polymer is a member selected from the group consisting of a blowing agent solvent imbibable polyetherimide, a linear polycarbonate and a polymer blend of polyphenylene oxide and polystyrene and wherein said polymer in its unfoamed particulate form is capable of imbibing said blowing agent selected from the group consisting of methylene chloride, chloroform, 1,1,2-trichloroethane and mixtures thereof with an amount of blowing agent sufficient to foam said polymer in a mold to a density of less than 18 lbs./ft 3 .
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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) | 1991-06-21 | 1991-12-21 | 1992-06-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-06-21 | 1995-12-21 | 1996-06-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-06-21 | 1999-12-21 | 2000-06-21 | $7700.00 | Window Closed / Lapsed |