US4889671A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Production method of prefoamed particles of polyolefin resin
Assignee: JSP Corp
•
Filing: 1988-05-11
•
Granted: 1989-12-26
•
Expires: 2008-05-11
Abstract
Abstract Prefoamed particles of a polyolefin resin are produced by dispersing starting particles of the polyolefin resin, which contains a volatile foaming agent, in a dispersant in a pressure vessel, heating the resultant dispersion to a temperature of at least the softening point of the starting particles in said pressure vessel and then opening the vessel at one end thereof so as to release the starting particles and dispersant into an atmosphere of a pressure lower than the internal pressure of the vessel. The release of the starting particles and dispersant is performed while feeding a heating liquid.
Inventors
- 👤 Hiroyuki Akiyama
- 👤 Susumu Izawa
- 👤 Hideki Kuwabara
- 👤 Toru Yamaguchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 08:48
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/22; C08J9/228; C08J2323/00; C08J2323/02; Y; Y10; Y10S; Y10S264/00; Y10S264/09; Y10S264/13; Y10S264/15; Y10S264/16
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
116 words
A method for producing prefoamed particles of a polyolefin resin by dispersing starting particles of the polyolefin resin, which contains a volatile foaming agent, in a dispersant in a pressure vessel, heating the resultant dispersion to a temperature of at least the softening point of the starting particles in said pressure vessel and then opening the vessel at one end thereof so as to release the starting particles and dispersant into an atmosphere of a pressure lower than the internal pressure of the vessel, which comprises feeding a heating liquid into the vessel while the starting particles and the dispersant are being released, thereby minimizing a change in the partial pressure of the volatile foaming agent.
Claim 2
Independent Claim
116 words
A method for producing prefoamed particles of a polyolefin resin by dispersing starting particles of the polyolefin resin, which contains a volatile foaming agent, in a dispersant in a pressure vessel, heating the resultant dispersion to a temperature of at least the softening point of the starting particles in said pressure vessel and then opening the vessel at one end thereof so as to release the starting particles and dispersant into an atmosphere of a pressure lower than the internal pressure of the vessel, which comprises feeding a heating liquid into the vessel while the starting particles and the dispersant are being released, thereby minimizing a change in the partial pressure of the volatile foaming agent.
Claim 3
Dependent Claim
46 words
The method as claimed in claim 1, wherein the release of the starting particles and dispersant is performed while feeding the heating liquid into the pressure vessel in a volume nearly equal to the total volume of the starting particles and dispersant which have been released.
Claim 4
Dependent Claim
42 words
The method as claimed in claim 1 or 2, wherein the temperature of the heating liquid ranges from (T m - 20° C.) to (T m - 5° C.) in which T m means the melting completion temperature of the starting particles.
Claim 5
Dependent Claim
26 words
The method as claimed in claim 1, 2 or 3, wherein the heating liquid is fed at a rate of from 400 l/min to 20 l/min.
Claim 6
Dependent Claim
30 words
The method as claimed in claim 1, wherein the feeding of the heating liquid is continued until at least three-fourths of the initial charge of the starting particles is released.
Claim 7
Dependent Claim
16 words
The method as claimed in claim 1, wherein the polyolefin resin is an ethylenepropylene random copolymer.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-12-25 | 1993-06-26 | 1993-12-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-12-25 | 1997-06-26 | 1997-12-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-12-25 | 2001-06-26 | 2001-12-26 | $7700.00 | Window Closed / Lapsed |