US4911869A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Reimpregnation of plastic foam particles with CO2
Assignee: Lyondell Chemical Technology LP
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Filing: 1988-10-11
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Granted: 1990-03-27
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Expires: 2008-10-11
Abstract
Abstract The process of making foam moldings without the use of organic blowing agents involves the use of inorganic gases such as carbon dioxide, nitrogen, air, solid carbon dioxide and other pneumatogens. Because of the rapidity with which these gases diffuse out of the polymer particles, it is necessary to pre-expand the particles and then reimpregnate the particles with the same or different gas.
Inventors
- 👤 Bernard H. Meyer
- 👤 Joseph C. Kinslow
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 15:02
CPC Classifications
B; B29; B29C; B29C44/00; B29C44/34; B29C44/3461; C; C08; C08J; C08J9/00; C08J9/04; C08J9/12; C08J9/122; C08J9/16; C08J9/18
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
102 words
A process for foaming styrene polymers and copolymers, polymethyl methacrylate, methyl methacrylate copolymers, cross-linked variations thereof and interpenetrating networks thereof comprising the steps of (a) impregnating particles of the polymer or copolymer with carbon dioxide for at least 1 hour to obtain 1-25% 25% carbon dioxide absorption; (b) expanding these particles at a temperature above the glass transition temperature of the polymer-carbon dioxide blend; (c) reimpregnation of the expanded particles in air, nitrogen, gaseous carbon dioxide, or in the presence of liquid or solid carbon dioxide or other pneumatogens; and (d) molding said reimpregnated expanded particles by heating in foam molding machines.
Claim 2
Dependent Claim
102 words
A process for foaming styrene polymers and copolymers, polymethyl methacrylate, methyl methacrylate copolymers, cross-linked variations thereof and interpenetrating networks thereof comprising the steps of (a) impregnating particles of the polymer or copolymer with carbon dioxide for at least 1 hour to obtain 1-25% 25% carbon dioxide absorption; (b) expanding these particles at a temperature above the glass transition temperature of the polymer-carbon dioxide blend; (c) reimpregnation of the expanded particles in air, nitrogen, gaseous carbon dioxide, or in the presence of liquid or solid carbon dioxide or other pneumatogens; and (d) molding said reimpregnated expanded particles by heating in foam molding machines.
Claim 3
Dependent Claim
11 words
The process of claim 1 wherein the styrene polymer is polystyrene.
Claim 4
Dependent Claim
21 words
The process of claim 1 wherein the styrene copolymer is a styrene-maleic anhydride copolymer containing 5 to 35 mole-% maleic anhydride.
Claim 5
Dependent Claim
13 words
The process of claim 1 wherein the styrene copolymer is a styrene-acrylonitrile copolymer.
Claim 6
Dependent Claim
13 words
The process of claim 1 wherein the styrene copolymer is an acrylonitrile-butadiene-styrene copolymer.
Claim 7
Dependent Claim
14 words
The process of claim 1 wherein the styrene copolymer is a styrene-methyl methacrylate copolymer.
Claim 8
Dependent Claim
16 words
The process of claim 1 wherein the styrene copolymer is a high impact rubber modified polystyrene.
Claim 9
Dependent Claim
24 words
The process of claim 1 wherein the reimpregnation is accomplished with a mixture of carbon dioxide and a minor amount of hydrocarbon blowing agent.
References Cited (Backward Citations)
US2768407A
Cited
US2531665A
Cited
US2714747A
Cited
US2751627A
Cited
US2714748A
Cited
US2848427A
Cited
US3243485A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-03-26 | 1993-09-25 | 1994-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-03-26 | 1997-09-25 | 1998-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-03-26 | 2001-09-25 | 2002-03-27 | $7700.00 | Window Closed / Lapsed |