US4483809A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for preparing polyolefin foam
Assignee: Kanegafuchi Chemical Industry Co Ltd
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Filing: 1983-01-14
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Granted: 1984-11-20
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Expires: 2003-01-14
Abstract
Abstract The present invention relates to a process for preparing a polyolefin foam by heat-molding pre-expanded beads of an expandable polyolefin resin containing a foaming agent in a mold, said process being improved in preparing beads having a peak expansion rate at pre-expansion equal to 1.3 to 3 times the expansion rate of beads to be packed into the mold, adjusting the beads to a pre-expansion rate depending on an expansion rate of the desired foam, and packing and molding the pre-expanded beads in a mold without any further addition of expandability thereto. The polyolefin foam prepared by the process of the present invention is evenly fused to the interior and is less liable to shrink or deform.
Inventors
- 👤 Masao Ando
- 👤 Kenkichi Tanaka
- 👤 Kiroku Sato
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 22:25
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/22; C08J9/228; C08J9/232; C08J2323/00; C08J2323/02; Y; Y10; Y10S; Y10S264/00; Y10S264/05; Y10S264/15; Y10S264/18
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
107 words
In a process for preparing a polyolefin foam by impregnating polyolefin resin particles with a foaming agent, pre-expanding the polyolefin resin particles to give pre-expanded beads, adjusting the beads to a pre-expansion rate depending on an expansion rate of the desired foam, packing and heat-molding the pre-expanded beads in a mold, the improvement which comprises preparing pre-expanded beads having a peak expansion rate at the pre-expansion step equal to 1.3 to 3 times the expansion rate of the beads to be packed into the mold, and adjusting at the adjusting step an internal pressure of the beads to be packed into the mold to substantially atmospheric pressure.
Claim 2
Dependent Claim
107 words
In a process for preparing a polyolefin foam by impregnating polyolefin resin particles with a foaming agent, pre-expanding the polyolefin resin particles to give pre-expanded beads, adjusting the beads to a pre-expansion rate depending on an expansion rate of the desired foam, packing and heat-molding the pre-expanded beads in a mold, the improvement which comprises preparing pre-expanded beads having a peak expansion rate at the pre-expansion step equal to 1.3 to 3 times the expansion rate of the beads to be packed into the mold, and adjusting at the adjusting step an internal pressure of the beads to be packed into the mold to substantially atmospheric pressure.
Claim 3
Dependent Claim
13 words
The process of claim 1, wherein said polyolefin resin is a cross-linked polyethylene.
Claim 4
Dependent Claim
14 words
The process of claim 1, wherein said polyolefin resin is a propylene-ethylene random copolymer.
Claim 5
Dependent Claim
130 words
In a process for preparing polyolefin foam by impregnating polyolefin resin particles with a foaming agent, pre-expanding the polyolefin resin particles to give pre-expanded beads, adjusting the beads to a pre-expansion rate depending on an expansion rate of the desired foam, packing and heat-molding the pre-expanded beads in a mold, the improvement which comprises preparing pre-expanded beads having a peak expansion rate at the pre-expansion step equal to 1.3 to 3 times the expansion rate of the beads to be packed into the mold, adjusting at the adjusting step an internal pressure of the beads to be packed into the mold to substantially atmospheric pressure, and holding the resultant molding in an atmosphere whose temperature is less than the melting point of the polyolefin resin by 20° to 50° C.
Claim 6
Dependent Claim
130 words
In a process for preparing polyolefin foam by impregnating polyolefin resin particles with a foaming agent, pre-expanding the polyolefin resin particles to give pre-expanded beads, adjusting the beads to a pre-expansion rate depending on an expansion rate of the desired foam, packing and heat-molding the pre-expanded beads in a mold, the improvement which comprises preparing pre-expanded beads having a peak expansion rate at the pre-expansion step equal to 1.3 to 3 times the expansion rate of the beads to be packed into the mold, adjusting at the adjusting step an internal pressure of the beads to be packed into the mold to substantially atmospheric pressure, and holding the resultant molding in an atmosphere whose temperature is less than the melting point of the polyolefin resin by 20° to 50° C.
Claim 7
Dependent Claim
13 words
The process of claim 4, wherein said polyolefin resin is a cross-linked polyethylene.
Claim 8
Dependent Claim
20 words
The process of claim 5, wherein said cross-linked polyethylene is a low-density polyethylene having a density of 0.91 to 0.93.
Claim 9
Dependent Claim
14 words
The process of claim 4, wherein said polyolefin resin is a propylene-ethylene random copolymer.
References Cited (Backward Citations)
US2787809A
Cited
US2744291A
Cited
US2816827A
Cited
US3504068A
Cited
US3804378A
Cited
US3725320A
Cited
US3856719A
Cited
US3953558A
Cited
JPS49128065A
Cited
JPS5188566A
Cited
JPS5222951A
Cited
JPS5333996A
Cited
US4150077A
Cited
JPS557816A
Cited
US4368276A
Cited
US4399087A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-11-20 | 1988-05-21 | 1988-11-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-11-20 | 1992-05-21 | 1992-11-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-11-20 | 1996-05-21 | 1996-11-20 | $7700.00 | Window Closed / Lapsed |