US4098941A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polystyrene foam extrusion
Assignee: Mobil Oil AS
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Filing: 1976-12-08
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Granted: 1978-07-04
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Expires: 1996-12-08
Abstract
Abstract Polystyrene foam is extruded upwardly as a tube into a cooling media of boiling water, both the interior and exterior surfaces of the cylindrically shaped extrudate passing through a bath of boiling water of variable depth. The polystyrene foam extrudate produced by such a method has a high density at the interior and exterior surfaces, with the density progressively decreasing from these surfaces toward the center core of the extrudate.
Inventors
- 👤 David Emil Johnson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 19:35
CPC Classifications
B; B29; B29C; B29C44/00; B29C44/34; B29C44/36; B29C44/46; B29C44/50; B29C44/507; B29L; B29L2023/00; Y; Y10; Y10S; Y10S138/00; Y10S138/09; Y10T; Y10T428/00; Y10T428/24; Y10T428/24942; Y10T428/24992; Y10T428/249921; Y10T428/249953; Y10T428/249961
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
126 words
An integral polystyrene foam extrudate having a density gradient from the central core of said article to the surfaces of said article; said surfaces having a density of about 65 to about 55 lb/ft 3 ; and said core having a density of about 1.3 to about 3 lb/ft 3 , said core representing not less than 95% of the thickness of said extrudate, said polystyrene foam having been produced in accordance with a method comprising extruding said foamable composition in tubular form directly into boiling water maintained at substantially the same height, both inside and outside said tubular extrudate; foaming said extrudate in said boiling water under cooling conditions whereby said tubular extrudate as formed has a density gradient decreasing from the external surfaces inwardly.
Claim 2
Dependent Claim
126 words
An integral polystyrene foam extrudate having a density gradient from the central core of said article to the surfaces of said article; said surfaces having a density of about 65 to about 55 lb/ft 3 ; and said core having a density of about 1.3 to about 3 lb/ft 3 , said core representing not less than 95% of the thickness of said extrudate, said polystyrene foam having been produced in accordance with a method comprising extruding said foamable composition in tubular form directly into boiling water maintained at substantially the same height, both inside and outside said tubular extrudate; foaming said extrudate in said boiling water under cooling conditions whereby said tubular extrudate as formed has a density gradient decreasing from the external surfaces inwardly.
Claim 3
Dependent Claim
22 words
A product as claimed in claim 1 wherein said boiling water temperature is within the range of about 170° to 230° F.
Claim 4
Dependent Claim
22 words
The product as claimed in claim 2 wherein said polystyrene extrudate temperature is within the range of about 270° to 320° F.
Claim 5
Dependent Claim
19 words
The product as claimed in claim 1 wherein said core represents about 97% of the thickness of said extrudate.
References Cited (Backward Citations)
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Cited
US3099516A
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US3189243A
Cited
US3299192A
Cited
US3363034A
Cited
US3523988A
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US3391051A
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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) | 1981-07-03 | 1982-01-02 | 1982-07-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-07-03 | 1986-01-02 | 1986-07-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-07-03 | 1990-01-02 | 1990-07-04 | $7700.00 | Window Closed / Lapsed |