US4766159A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for producing polypropylene foam
Assignee: Tonen Chemical Corp
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Filing: 1987-06-22
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Granted: 1988-08-23
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Expires: 2007-06-22
Abstract
Abstract The invention relates to the process of the invention provides a radiation-crosslinked polypropylene foam by extrusion at a low temperature (about 170° C.) below the decomposition point of the blowing agent. The resulting foamed item has by far better heat resistance than conventional ones. The raw resin can be prepared by mixing a resin in the pellet form and a blowing agent in the powder form on account of the low-temperature flowability. Heretofore, such mixing was impossible because the blowing agent does not disperse completely. This outstanding effect of the invention was not expected at all from the known prior arts.
Inventors
- 👤 Sotoyuki Kitagawa
- 👤 Takashi Nakayama
- 👤 Masatoshi Isono
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 20:34
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/04; C08J9/06; C08J9/10; C08J2323/00; C08J2323/02; C08J2323/10; C08J2323/12; C08J2353/00; Y; Y10; Y10S; Y10S264/00; Y10S264/17; Y10S521/00; Y10S521/915
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
53 words
In a process for the production of polypropylene foam comprising mixing polypropylene with a blowing agent and crosslinking auxiliary, molding the mixture, crosslinking the molded mixture and foaming, the improvement comprising employing a polypropylene selected from homo-polypropylene or block-polyproplene containing 1-20 wt % ethylene and having a MFR in the range of 30-100.
Claim 2
Dependent Claim
53 words
In a process for the production of polypropylene foam comprising mixing polypropylene with a blowing agent and crosslinking auxiliary, molding the mixture, crosslinking the molded mixture and foaming, the improvement comprising employing a polypropylene selected from homo-polypropylene or block-polyproplene containing 1-20 wt % ethylene and having a MFR in the range of 30-100.
Claim 3
Dependent Claim
16 words
The process according to claim 1 wherein the polypropylene further comprises 40-60 wt % random polypropylene.
References Cited (Backward Citations)
US3882209A
Cited
US4154785A
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US4303757A
Cited
US4421867A
Cited
US4367185A
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US4424293A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-08-23 | 1992-02-22 | 1992-08-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-08-23 | 1996-02-22 | 1996-08-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-08-23 | 2000-02-22 | 2000-08-23 | $7700.00 | Window Closed / Lapsed |