Patent EP0142261A1 successfully refreshed from Google Patents.
US4579874A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polymer foam, thermoformed shapes thereof and methods of forming same
Assignee: Pactiv LLC
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Filing: 1985-07-26
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Granted: 1986-04-01
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Expires: 2005-07-26
Abstract
Abstract A foam structure having a density of less than about 20 lbs/ft3. The method of forming the same comprising forming a homogeneous melt blend under pressure of a polymer member selected from the group consisting of polyetherimide resin particles, polycarbonate resin particles, a polymer blend of polyphenylene oxide and polystyrene in particle form imbibed with a blowing agent, followed by extrusion of the same into a lower pressure atmosphere. A composition comprising said particles imbibed with methylene chloride, chloroform, 1,1,2-trichloroethane or mixtures thereof. A method of thermoforming said foam in sheet form.
Inventors
- 👤 Charles M. Krutchen
- 👤 Wen-Pao Wu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 11:05
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/04; C08J9/12; C08J9/14; C08J9/143; C08J9/144; C08J9/145; B; B29; B29C; B29C44/00; B29C44/34; B29C44/36; B29C44/46; B29C44/50; B29C44/507; B29C51/00; B29C51/002; B29K; B29K2079/00; C08J2379/00; C08J2379/04; C08J2379/08
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
94 words
The process of preparing a low density polycarbonate foam structure comprising: (a) providing polycarbonate in an extrusion system under pressure and melting the same; (b) homogeneously blending the molten polycarbonate with a blowing agent member selected from the group consisting of methylene chloride, chloroform, 1,1,2-trichloroethane and mixtures thereof, said blowing agent being present in a proportion sufficient to foam the polycarbonate to a density less than about 18 lbs./ft 3 ; and (c) extruding the melt blend into a lower pressure atmosphere to cause the blowing agent to vaporize yielding a polycarbonate foam structure.
Claim 2
Dependent Claim
94 words
The process of preparing a low density polycarbonate foam structure comprising: (a) providing polycarbonate in an extrusion system under pressure and melting the same; (b) homogeneously blending the molten polycarbonate with a blowing agent member selected from the group consisting of methylene chloride, chloroform, 1,1,2-trichloroethane and mixtures thereof, said blowing agent being present in a proportion sufficient to foam the polycarbonate to a density less than about 18 lbs./ft 3 ; and (c) extruding the melt blend into a lower pressure atmosphere to cause the blowing agent to vaporize yielding a polycarbonate foam structure.
Claim 3
Dependent Claim
13 words
The method of claim 1 wherein said polycarbonate has the chemical formula: ##STR3##
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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) | 1989-03-31 | 1989-09-30 | 1990-04-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-03-31 | 1993-09-30 | 1994-04-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-03-31 | 1997-09-30 | 1998-04-01 | $7700.00 | Window Closed / Lapsed |