Patent US4522955A successfully refreshed from Google Patents.
US4522955A
Expired / Lapsed
US
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Highly foamed polypropylene product and an extrusion process for forming the product
Assignee: Sumitomo Chemical Co Ltd
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Filing: 1982-05-19
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Granted: 1985-06-11
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Expires: 2002-05-19
Abstract
Abstract A process for producing a highly expanded polypropylene foam which is uniform in viscosity during extrusion foaming, improved in melt strength and free from unevenness of surface by using a polypropylene resin having a specified melt tension.
Inventors
- 👤 Nobuo Fukushima
- 👤 Yoshihiko Kitagawa
- 👤 Takuzo Okumura
- 👤 Kazuaki Sakakura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 16:37
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/04; C08J9/12; C08J9/14; C08J9/143; C08J9/147; B; B29; B29C; B29C48/00; B29C48/25; B29C48/78; B29C48/80; B29C48/83; B29C48/834; C08J2323/00; C08J2323/02; C08J2323/10; Y; Y10; Y10S; Y10S264/00; Y10S264/16
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
86 words
A non-crosslinking extrusion foaming process for producing a polypropylene highly foamed product which consists essentially of feeding a polypropylene resin having, at 190° C., a minimum value of melt tension of 3 g or more and a maximum/minimum ratio of melt tension of 2.5 or less into an extruder together with a nucleus-forming agent, melting them, thereafter feeding a volatile foaming agent into the barrel of the extruder, uniformly mixing the materials, and then extruding the mixture to a low pressure zone while cooling the mixture.
Claim 2
Dependent Claim
86 words
A non-crosslinking extrusion foaming process for producing a polypropylene highly foamed product which consists essentially of feeding a polypropylene resin having, at 190° C., a minimum value of melt tension of 3 g or more and a maximum/minimum ratio of melt tension of 2.5 or less into an extruder together with a nucleus-forming agent, melting them, thereafter feeding a volatile foaming agent into the barrel of the extruder, uniformly mixing the materials, and then extruding the mixture to a low pressure zone while cooling the mixture.
Claim 3
Dependent Claim
43 words
A process for producing a polypropylene highly foamed product according to claim 1, wherein said polypropylene resin has, at 190° C., a minimum value of melt tension of 5 g or more and a maximum/minimum ratio of melt tension of 2.0 or less.
Claim 4
Dependent Claim
34 words
A process for producing a polypropylene highly foamed product according to claim 1, wherein said volatile foaming agent is a mixture consisting of 90-30% by weight of trichlorotrifluoroethane and 10-70% by weight of dichlorotetrafluoroethane.
Claim 5
Dependent Claim
11 words
A foamed polypropylene product produced by the process of claim 1.
Claim 6
Dependent Claim
11 words
A foamed polypropylene product produced by the process of claim 2.
Claim 7
Dependent Claim
11 words
A foamed polypropylene product produced by the process of claim 3.
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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) | 1988-06-10 | 1988-12-10 | 1989-06-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-06-10 | 1992-12-10 | 1993-06-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-06-10 | 1996-12-10 | 1997-06-11 | $7700.00 | Window Closed / Lapsed |