US3756441A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Flash spinning process
Assignee: EIDP Inc
•
Filing: 1972-08-14
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Granted: 1973-09-04
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Expires: 1992-08-14
Abstract
Abstract Process for preparing high quality plexifilaments from isotactic polypropylene by flash extruding trichlorofluoromethane solutions at temperatures from 200* to 240*C. and pressures in excess of 900 psig, provided further that
Inventors
- 👤 R Anderson
- 👤 R Woodell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 01:16
CPC Classifications
E; E04; E04C; E04C3/00; E04C3/02; E04C3/12; D; D01; D01D; D01D5/00; D01D5/11; D01F; D01F6/00; D01F6/02; D01F6/04; D01F6/28; D01F6/30; E04B; E04B1/00; E04B1/18; E04B1/26; E04B1/2604
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
90 words
adjusting the temperature and pressure of the solution until the temperature is between about 200*C. and 240*C., the pressure on the sOlution is in excess of 900 psig; and the melt flow rate (MFR) of the isotactic polypropylene fulfills the following formula: (MFR/c) > or = 1.13 - 0.04 (T-220) in which c is the concentration of the isotactic polypropylene in the solution, expressed in weight percent and T is the temperature (*C.) of the solution, and wherein MFR is equal to a numeral between 2 and 30, inclusive; and
Claim 2
Dependent Claim
21 words
The process of claim 1 wherein the minimum MFR/c value is 15 percent greater than the value 1.13 - 0.04 (T-220).
Claim 3
Dependent Claim
20 words
The process of claim 1 wherein the temperature of the solution in step (2) is between about 220* and 235*C.
Claim 4
Dependent Claim
19 words
extruding said solution abruptly into a region of lower temperature and pressure so as to produce said plexifilamentary material.
Claim 5
Dependent Claim
20 words
The process of claim 2 wherein the temperature of the solution in step (2) is between about 220* and 235*C.
Claim 6
Dependent Claim
25 words
The process of claim 1 wherein the pressure on the solution in step (2) is high enough to maintain the solution as a single phase.
Claim 7
Dependent Claim
53 words
The process of claim 5 wherein, after step (2) and before step (3), the solution is passed through a pressure letdown chamber where the pressure on the solution is lowered to a point at which the solution forms a two-phase liquid, said solution remaining in said letdown chamber not more than 30 seconds.
Claim 8
Dependent Claim
21 words
The process of claim 6 wherein the minimum MFR/c value is 15 percent greater than the value 1.13 - 0.04 (T-220).
Claim 9
Dependent Claim
20 words
The process of claim 6 wherein the temperature of the solution in step (2) is between about 220* and 235*C.
Claim 10
Dependent Claim
20 words
The process of claim 7 wherein the temperature of the solution in step (2) is between about 220* and 235*C.
Claim 11
Dependent Claim
37 words
The process of claim 1 wherein the polypropylene has a MFR lower than that required to fit the equation in claim 1 and is thermally degraded in the solution to a value that does fit said equation.
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) | 1976-09-03 | 1977-03-05 | 1977-09-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-03 | 1981-03-05 | 1981-09-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-03 | 1985-03-05 | 1985-09-04 | $7700.00 | Window Closed / Lapsed |