US4925606A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for enhancing thermal expandability of direct-injection foams
Assignee: Lyondell Chemical Technology LP
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Filing: 1989-10-10
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Granted: 1990-05-15
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Expires: 2009-10-10
Abstract
Abstract The process of enabling foam moldings to expand further than otherwise by impregnating the expanded sheet with inorganic gases such as carbon dioxide, nitrogen, air and other pneumatogens prior to reheating to effect expansion.
Inventors
- 👤 Peter S. Francis
- 👤 Thomas M. Chapman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 02:23
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/04; C08J9/12; C08J9/122; C08J9/36; C08J9/40; C08J2201/00; C08J2201/02; C08J2201/03; C08J2201/032; Y; Y10; Y10S; Y10S264/00; Y10S264/15
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
127 words
A process for enhancing the expansion of foams of polystyrene, styrene copolymers, polymethyl methacrylate, methyl methacrylate copolymers, polyphenylene oxide, copolymers of styrene with from 5 to 35 mole percent of maleic anhydride and its derivatives, styrene-acrylonitrile, acrylonitrile-butadiene-styrene, styrene-methyl methacrylate, styrene-acrylic acid, styrene-methacrylic acid, the rubber modified high impact styrene copolymers, polyethylene, and polypropylene comprising the steps of (a) impregnating the polymer with a blowing agent in a first extruder and immediately cooling the polymer in a second extruder; (b) expanding the polymer by extrusion of the polymer to form a foamed sheet; (c) aging the foam sheet in air for 1-100 days; (d) impregnating the foamed sheet with gas, liquid, or solid carbon dioxide; and (e) immediately heating the impregnated foam sheet to further expand the sheet.
Claim 2
Dependent Claim
127 words
A process for enhancing the expansion of foams of polystyrene, styrene copolymers, polymethyl methacrylate, methyl methacrylate copolymers, polyphenylene oxide, copolymers of styrene with from 5 to 35 mole percent of maleic anhydride and its derivatives, styrene-acrylonitrile, acrylonitrile-butadiene-styrene, styrene-methyl methacrylate, styrene-acrylic acid, styrene-methacrylic acid, the rubber modified high impact styrene copolymers, polyethylene, and polypropylene comprising the steps of (a) impregnating the polymer with a blowing agent in a first extruder and immediately cooling the polymer in a second extruder; (b) expanding the polymer by extrusion of the polymer to form a foamed sheet; (c) aging the foam sheet in air for 1-100 days; (d) impregnating the foamed sheet with gas, liquid, or solid carbon dioxide; and (e) immediately heating the impregnated foam sheet to further expand the sheet.
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
14 words
The process of claim 1 wherein the styrene copolymer is a styrene-methacrylic acid copolymer.
Claim 10
Dependent Claim
11 words
The process of claim 1 wherein the polymer foam is polyethylene.
Claim 11
Dependent Claim
11 words
The process of claim 1 wherein the polymer foam is polypropylene.
References Cited (Backward Citations)
US2531665A
Cited
US2848427A
Cited
US3243485A
Cited
US4150077A
Cited
US4456573A
Cited
US4420448A
Cited
US4485059A
Cited
US4804507A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-05-14 | 1993-11-13 | 1994-05-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-05-14 | 1997-11-13 | 1998-05-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-05-14 | 2001-11-13 | 2002-05-15 | $7700.00 | Window Closed / Lapsed |