US4594208A
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: 1984-06-18
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Granted: 1986-06-10
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Expires: 2004-06-18
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 17:59
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; Y; Y10; Y10S; Y10S264/00; Y10S264/05; Y10S264/66; Y10S521/00; Y10S521/918
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
92 words
The process of preparing a low density polymer foam structure, said polymer being a solvent imbibable polyetherimide, comprising: (a) providing said polymer in particle form imbibed with a solvent member selected from the group consisting of methylene chloride, chloroform, 1,1,2-trichloroethane and mixtures thereof; (b) homogeneously melt blending said particles and solvent in an extrusion system under pressure; and (c) extruding said melt blend into a lower pressure atmosphere to cause said solvent to vaporize yielding a foam structure said foam structure having a density of less than about 20 lbs/ft 3 .
Claim 2
Dependent Claim
92 words
The process of preparing a low density polymer foam structure, said polymer being a solvent imbibable polyetherimide, comprising: (a) providing said polymer in particle form imbibed with a solvent member selected from the group consisting of methylene chloride, chloroform, 1,1,2-trichloroethane and mixtures thereof; (b) homogeneously melt blending said particles and solvent in an extrusion system under pressure; and (c) extruding said melt blend into a lower pressure atmosphere to cause said solvent to vaporize yielding a foam structure said foam structure having a density of less than about 20 lbs/ft 3 .
Claim 3
Dependent Claim
13 words
The method of claim 1 wherein said particles are at least substantially anhydrous.
Claim 4
Dependent Claim
49 words
The method of claim 1 wherein said polyetherimide is a polymer of the following structure: ##STR3## wherein n is a positive number, Ar is a divalent radical containing from 6-20 carbon atoms, R is a bivalent radical selected from the group consisting of aliphatic, cycloaliphatic, aromatic and araliphatic groups.
Claim 5
Dependent Claim
17 words
The method of claim 3 wherein the precursor of Ar is Bisphenol A and R is phenylene.
Claim 6
Dependent Claim
22 words
The process of claim 4 wherein said particles and solvent are homogeneously melt blended at a temperature less than about 500° F.
Claim 7
Dependent Claim
16 words
The process of claim 5 wherein said temperature is between about 425° and about 450° F.
Claim 8
Independent Claim
80 words
The method of preparing a thermoformed structure of a polyetherimide foam, comprising: (a) subjecting a sheet of said foam having a density of less than 20 lbs/ft 3 to a first temperature sufficient to permit a shape formation to be effected therein; (b) effecting a shape in said sheet while at said temperature; and (c) reducing the temperature of said sheet to a second temperature permitting permanent retention of said shape in said sheet at or below said second temperature.
Claim 9
Independent Claim
80 words
The method of preparing a thermoformed structure of a polyetherimide foam, comprising: (a) subjecting a sheet of said foam having a density of less than 20 lbs/ft 3 to a first temperature sufficient to permit a shape formation to be effected therein; (b) effecting a shape in said sheet while at said temperature; and (c) reducing the temperature of said sheet to a second temperature permitting permanent retention of said shape in said sheet at or below said second temperature.
References Cited (Backward Citations)
US3277029A
Cited
US3962154A
Cited
US4315076A
Cited
US4361453A
Cited
US4367296A
Cited
US4360486A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-06-09 | 1989-12-09 | 1990-06-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-06-09 | 1993-12-09 | 1994-06-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-06-09 | 1997-12-09 | 1998-06-10 | $7700.00 | Window Closed / Lapsed |