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Patent US3725320A successfully refreshed from Google Patents.
US3725320A
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US
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Aging of impregnated foamable beads
Assignee: Dart Industries Inc
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Filing: 1972-04-03
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Granted: 1973-04-03
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Expires: 1992-04-03
Abstract
Abstract A process for aging polymer beads which have been impregnated with a volatile blowing agent wherein the improvement consists of aging in an inert atmosphere at controlled temperature to reduce the volatile impregnant content. The aging can be accelerated safely with incremental temperature increases.
Inventors
- 👤 J Wang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 06:52
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/22; Y; Y10; Y10S; Y10S264/00; Y10S264/15
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
19 words
The process of claim 1, wherein the particles at least intermittently are agitated having contact with said inert atmosphere.
Claim 2
Dependent Claim
23 words
The process of claim 1, wherein the particles comprise styrenic beads and the impregnant is a lower aliphatic hydrocarbon having 3-6 carbon atoms.
Claim 3
Dependent Claim
26 words
The process of claim 1, wherein for the first 6 hours of said period of time the temperature of the particles are maintained below about 80*F.
Claim 4
Dependent Claim
30 words
The process of claim 1, wherein the flow rate of inert gas is about 0.5 to about 6 standard cubic feet per minute per 100 pounds of synthetic resin particles.
Claim 5
Dependent Claim
11 words
The process of claim 1, wherein the inert gas is nitrogen.
Claim 6
Dependent Claim
23 words
The process of claim 1, wherein the inlet temperature of the inert gas is increased in increments during the duration of the aging.
Claim 7
Dependent Claim
15 words
The process of claim 1, wherein the inert gas is recycled with recovery of impregnant.
Claim 8
Dependent Claim
24 words
The process of claim 1 wherein the volatile content of the recovered aged unexpanded particles is between about 4.5 and about 6 weight percent.
Claim 9
Dependent Claim
23 words
The process of claim 1 wherein the unexpanded resin particles initially contain from about 8 to about 10 percent by weight of impregnant.
Claim 10
Dependent Claim
19 words
The process of claim 3, wherein the particles initially contain from about 8 to about 10 weight percent butane.
Claim 11
Dependent Claim
126 words
A process for aging unexpanded synthetic resin particles impregnated with a volatile impregnant which comprises: maintaining in an aging zone a bed of impregnated unexpanded particles initially containing above 7 percent by weight of impregnant; maintaining substantially atmospheric pressure conditions within said zone during the aging; passing an inert gas through said bed of particles having an inlet temperature in the range from about 50* to about 110*F; maintaining the temperature of the bed below about 80*F for at least about the first 2 hours of the aging; increasing the inlet temperature of the inert gas in increments within the aforementioned range during the aging, and recovering aged, unexpanded particles having a volatile content in the range from about 4 to about 7 percent by weight.
References Cited (Backward Citations)
US3126432A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-04-02 | 1976-10-02 | 1977-04-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-02 | 1980-10-02 | 1981-04-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-02 | 1984-10-02 | 1985-04-03 | $7700.00 | Window Closed / Lapsed |