US4436840A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for producing pre-foamed particles of polyolefin resin
Assignee: JAPAN STYRENE PAPER Corp 1-1 2-CHOME UCHISAIWAI-CHO CHIYODA-KU TOKYO JAPAN A CORP OF JAPAN
•
Filing: 1982-09-21
•
Granted: 1984-03-13
•
Expires: 2002-09-21
Abstract
Abstract In a process for producing pre-foamed particles of a polyolefin resin which comprises impregnating a volatile blowing agent into particles of a polyolefin resin while dispersing the resin particles and the blowing agent in a dispersing medium under heat in a closed vessel, opening one end of the vessel and releasing the resin particles and the dispersing medium simultaneously into an atmosphere kept at a lower pressure than the inside pressure of the vessel; the improvement wherein the pressure of the inside of the vessel after opening its one end is maintained at a substantially constant pressure which is at least 0.7 times the vapor pressure f of the blowing agent before opening the end of the vessel.
Inventors
- 👤 Hiroyuki Akiyama
- 👤 Sumio Shimada
- 👤 Kuninori Hirosawa
- 👤 Hideki Kuwabara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 03:52
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/16; C08J9/18; C08J2203/00; C08J2203/14; C08J2203/142; C08J2323/00; C08J2323/02; Y; Y10; Y10S; Y10S264/00; Y10S264/09
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
125 words
In a process for producing pre-foamed particles of a polyolefin resin which comprises impregnating a volatile blowing agent into particles of a polyolefin resin while dispersing the resin particles and the blowing agent in a liquid dispersing medium which does not dissolve the resin particles under heat in a closed vessel, opening one end of the vessel and releasing the resin particles and the dispersing medium simultaneously into an atmosphere kept at a lower pressure than the inside pressure of the vessel; the improvement wherein the pressure of the inside of the vessel after opening its one end is maintained at a substantially constant pressure which is at least 0.7 times the vapor pressure of the blowing agent before opening the end of the vessel.
Claim 2
Dependent Claim
125 words
In a process for producing pre-foamed particles of a polyolefin resin which comprises impregnating a volatile blowing agent into particles of a polyolefin resin while dispersing the resin particles and the blowing agent in a liquid dispersing medium which does not dissolve the resin particles under heat in a closed vessel, opening one end of the vessel and releasing the resin particles and the dispersing medium simultaneously into an atmosphere kept at a lower pressure than the inside pressure of the vessel; the improvement wherein the pressure of the inside of the vessel after opening its one end is maintained at a substantially constant pressure which is at least 0.7 times the vapor pressure of the blowing agent before opening the end of the vessel.
Claim 3
Dependent Claim
54 words
The process of claim 1 wherein the pressure of the inside of the vessel after opening its one end is maintained at a substantially constant pressure which is at least 0.7 times the vapor pressure of the blowing agent before opening the end of the vessel and which fluctuates within 4 kg/cm 2 .
References Cited (Backward Citations)
US3428720A
Cited
US4032609A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-03-13 | 1987-09-12 | 1988-03-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-03-13 | 1991-09-12 | 1992-03-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-03-13 | 1995-09-12 | 1996-03-13 | $7700.00 | Window Closed / Lapsed |