US4579710A
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: 1985-07-19
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Granted: 1986-04-01
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Expires: 2005-07-19
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
2026-10-31 13:32
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: 7
Claim 1
Independent Claim
86 words
The process of preparing a low density polymer foam structure, said polymer being a solvent imbibable polycarbonate comprising: (a) providing said polycarbonate in particle form imbibed with a solvent member selected from the group consisting of methylene cloride, chloroform, 1,1,2-trichloroethane and mixtures thereof; (b) homogeneously blending said particles and solvent in an extrusion system under pressure; and (c) extruding said blend into a lower pressure atmosphere to cause said solvent to vaporize yielding a foam structure of a density less than about 18 lbs./ft 3 .
Claim 2
Dependent Claim
86 words
The process of preparing a low density polymer foam structure, said polymer being a solvent imbibable polycarbonate comprising: (a) providing said polycarbonate in particle form imbibed with a solvent member selected from the group consisting of methylene cloride, chloroform, 1,1,2-trichloroethane and mixtures thereof; (b) homogeneously blending said particles and solvent in an extrusion system under pressure; and (c) extruding said blend into a lower pressure atmosphere to cause said solvent to vaporize yielding a foam structure of a density less than about 18 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
14 words
The method of claim 1 wherein said polycarbonate has the following chemical structure: ##STR3##
Claim 5
Dependent Claim
20 words
The process of claim 1 wherein said foam structure has a density of less than about 5 lbs./ft. 3 .
Claim 6
Independent Claim
81 words
The method of preparing a thermoformed structure of a polycarbonate foam comprising: (a) subjecting a sheet of said foam having a density of less than 18 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 its 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 7
Independent Claim
81 words
The method of preparing a thermoformed structure of a polycarbonate foam comprising: (a) subjecting a sheet of said foam having a density of less than 18 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 its 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.
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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 |