US5252269A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for molding polypropylene resin
Assignee: Sumitomo Chemical Co Ltd
•
Filing: 1991-10-04
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Granted: 1993-10-12
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Expires: 2011-10-04
Abstract
Abstract A method for molding a foamed particle of a polypropylene resin. The polypropylene resin includes a homopolymer and copolymer of polypropylene resin, as well as a mixture of a polypropylene resin and another resin.
Inventors
- 👤 Takahisa Hara
- 👤 Masahito Matsumoto
- 👤 Nobuhiro Usui
- 👤 Shigeyoshi Matubara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 17:20
CPC Classifications
B; B29; B29C; B29C44/00; B29C44/02; B29C44/10; B29C67/00; B29C67/20
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
186 words
A method for producing a foamed article of a polypropylene resin, which comprises steps of: providing a pair of male and female molds (3,4) which are slidably moved at an engaged part (5) and in which a cavity clearance (t) is freely set, starting supply of a melt of a polypropylene resin (8) containing a chemical blowing agent through a resin melt conduit (7) which is provided in one of said male and female molds when said cavity clearance (t) is 1.0 mm or less, moving at least one of said male and female molds to increase said cavity clearance (t) during said supply of said polypropylene resin melt (8) so that a pressure on said resin melt in said mold cavity is adjusted in a range between 5 kg/cm 2 and 100 kg/cm 2 , forming a skin layer by applying a pressure of from 5 kg/cm 2 to 100 kg/cm 2 on said resin melt (8) as soon as said resin supply is finished, further increasing said cavity clearance (t) to form a foamed core layer and cooling a foamed article in said molds.
Claim 2
Independent Claim
186 words
A method for producing a foamed article of a polypropylene resin, which comprises steps of: providing a pair of male and female molds (3,4) which are slidably moved at an engaged part (5) and in which a cavity clearance (t) is freely set, starting supply of a melt of a polypropylene resin (8) containing a chemical blowing agent through a resin melt conduit (7) which is provided in one of said male and female molds when said cavity clearance (t) is 1.0 mm or less, moving at least one of said male and female molds to increase said cavity clearance (t) during said supply of said polypropylene resin melt (8) so that a pressure on said resin melt in said mold cavity is adjusted in a range between 5 kg/cm 2 and 100 kg/cm 2 , forming a skin layer by applying a pressure of from 5 kg/cm 2 to 100 kg/cm 2 on said resin melt (8) as soon as said resin supply is finished, further increasing said cavity clearance (t) to form a foamed core layer and cooling a foamed article in said molds.
Claim 3
Dependent Claim
23 words
The method according to claim 1, wherein the resin melt supply is started when said cavity clearance (t) is 0.5 mm or less.
Claim 4
Dependent Claim
15 words
The method according to claim 1, wherein said polypropylene resin is a homopolymer of propylene.
Claim 5
Dependent Claim
21 words
The method according to claim 1, wherein said polypropylene resin is a copolymer of propylene with at least one other monomer.
Claim 6
Dependent Claim
15 words
The method according to claim 4, wherein said at least one other monomer is ethylene.
Claim 7
Dependent Claim
26 words
The method according to claim 1, wherein said polypropylene resin is a mixture of at least 50% by weight of a polypropylene resin and another resin.
Claim 8
Dependent Claim
29 words
The method according to claim 1, wherein said polypropylene resin is a mixture of at least 50% by weight of a polypropylene resin and polyethylene or a thermoplastic elastomer.
Claim 9
Dependent Claim
14 words
The method according to claim 1, wherein said foam article further comprises a filler.
Claim 10
Dependent Claim
14 words
The method according to claim 8, wherein said filler is calcium carbonate or talc.
Claim 11
Dependent Claim
16 words
The method according to claim 1, wherein said chemical blowing agent is sodium bicarbonate or azodicarbonamide.
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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) | 1996-10-11 | 1997-04-12 | 1997-10-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-10-11 | 2001-04-12 | 2001-10-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-10-11 | 2005-04-12 | 2005-10-12 | $7700.00 | Window Closed / Lapsed |