US4485059A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polymer foam thermoformation process and apparatus therefor
Assignee: Pactiv LLC
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Filing: 1983-04-28
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Granted: 1984-11-27
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Expires: 2003-04-28
Abstract
Abstract A method of thermoforming comprising providing a continuous sheet of thermoplastic polymeric foam, transporting said sheet through an atmosphere of at least predominantly steam at a temperature of at least 215° F. maintaining said sheet in said atmosphere for a time sufficient to cause a decrease in the density thereof; thereafter while under the influence of said temperature, deforming at least a portion of said sheet to a predetermined shape and while so deformed, cooling the same to cause retention of said shape and a system for carrying out said method.
Inventors
- 👤 Charles M. Krutchen
- 👤 Wen-Pao Wu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 01:37
CPC Classifications
B; B29; B29C; B29C44/00; B29C44/34; B29C44/56; B29C44/5627; B29C44/5636; B29C51/00; B29C51/26; B29C51/42; B29C51/421; B29C35/00; B29C35/02; B29C35/04; B29K; B29K2105/00; B29K2105/04; B29L; B29L2007/00; B29L2007/008; Y; Y10; Y10S; Y10S264/00; Y10S264/15; Y10S264/65; Y10S425/00; Y10S425/039
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
93 words
A method of thermoforming comprising: (a) providing a continuous sheet of thermoplastic polymeric foam; (b) transporting said sheet thru an atmosphere of at least predominantly steam at a temperature of at least 215° F., any non-steam component being composed of air; (c) maintaining said sheet in said atmosphere for a time sufficient to cause a decrease in its density; (d) thereafter while under the influence of said temperature, deforming at least a portion of said sheet to a predetermined shape; and (e) while so-deformed, cooling the same to cause retention of said shape.
Claim 2
Independent Claim
93 words
A method of thermoforming comprising: (a) providing a continuous sheet of thermoplastic polymeric foam; (b) transporting said sheet thru an atmosphere of at least predominantly steam at a temperature of at least 215° F., any non-steam component being composed of air; (c) maintaining said sheet in said atmosphere for a time sufficient to cause a decrease in its density; (d) thereafter while under the influence of said temperature, deforming at least a portion of said sheet to a predetermined shape; and (e) while so-deformed, cooling the same to cause retention of said shape.
Claim 3
Dependent Claim
25 words
The method of claim 1 wherein said atmosphere is at a temperature of from about 215° F. to below the sag temperature of said sheet.
Claim 4
Dependent Claim
15 words
The method of claim 2 wherein said thermoplastic polymeric foam sheet is a styrenic polymer.
Claim 5
Dependent Claim
21 words
The method of claim 3 wherein said styrenic polymer is a member selected from the group consisting of polystyrene and poly(p-methylstyrene).
Claim 6
Dependent Claim
17 words
The method of claim 4 wherein said temperature is from about 215° F. to about 275° F.
Claim 7
Dependent Claim
14 words
The method of claim 5 wherein said density decrease is at least about 33%.
Claim 8
Independent Claim
92 words
A system for thermoforming a continuous sheet of thermoplastic foam comprising in combination: (a) means for transporting said foam in single layer form; (b) means for treating said foam, during its transport in single layer form, with an atmosphere of predominantly steam at a temperature of at least 215° F., any non-steam component being composed of air; and (c) means in association therewith for receiving said sheet in thermoformable condition, for deforming at least a portion of said sheet to a predetermined shape and for cooling the same to retain said shape.
Claim 9
Independent Claim
92 words
A system for thermoforming a continuous sheet of thermoplastic foam comprising in combination: (a) means for transporting said foam in single layer form; (b) means for treating said foam, during its transport in single layer form, with an atmosphere of predominantly steam at a temperature of at least 215° F., any non-steam component being composed of air; and (c) means in association therewith for receiving said sheet in thermoformable condition, for deforming at least a portion of said sheet to a predetermined shape and for cooling the same to retain said shape.
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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) | 1987-11-27 | 1988-05-28 | 1988-11-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-11-27 | 1992-05-28 | 1992-11-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-11-27 | 1996-05-28 | 1996-11-27 | $7700.00 | Window Closed / Lapsed |