US3969324A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Continuous process for drying, crystallizing and solid state polymerizing polyesters
Assignee: Monsanto Co
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Filing: 1973-11-12
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Granted: 1976-07-13
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Expires: 1993-11-12
Abstract
Abstract A continuous process is provided for the drying, crystallizing and solid state polymerization of fiber-forming crystallizable polyesters by subjecting polyester pellets of a specific viscosity of about 0.34, with a carboxyl concentration of about 15 milequivalents per gram and a particle size of between -10 and +20 mesh, to a temperature of not more than about 80°C. until the water content of the flake is below 0.05%; and then raising the temperature to about 230°-240°C. until the specific viscosity of the polymer is equal to or greater than about 0.55.
Inventors
- 👤 Eugene E. Berkau
- 👤 Cecil W. Capps
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 17:46
CPC Classifications
C; C08; C08G; C08G63/00; C08G63/78; C08G63/80; B; B01; B01J; B01J19/00; B01J19/18; B01J19/20
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
130 words
A continuous process for drying, crystallizing and solid state polymerizing of fiber-forming crystallizable polyesters comprising conveying in a screw-type conveyor in a partial vacuum of about 0.5 mm Hg. through the transitionally coordinated steps of: (1) drying pellets of a specific viscosity of about 0.34, a carboxyl concentration of about 15 milequivalents per gram, and a particle size of between -10 and +20 mesh, at a temperature of not more than about 80°C until the water content of the flake is below 0.05%; then (2) crystallizing the pellets in a second zone during which the temperature is raised to about 230° - 240°C; and (3) solid state polymerizing the pellets at about 230° - 240°C until the specific viscosity of the polymer is about equal to or greater than 0.55.
Claim 2
Dependent Claim
130 words
A continuous process for drying, crystallizing and solid state polymerizing of fiber-forming crystallizable polyesters comprising conveying in a screw-type conveyor in a partial vacuum of about 0.5 mm Hg. through the transitionally coordinated steps of: (1) drying pellets of a specific viscosity of about 0.34, a carboxyl concentration of about 15 milequivalents per gram, and a particle size of between -10 and +20 mesh, at a temperature of not more than about 80°C until the water content of the flake is below 0.05%; then (2) crystallizing the pellets in a second zone during which the temperature is raised to about 230° - 240°C; and (3) solid state polymerizing the pellets at about 230° - 240°C until the specific viscosity of the polymer is about equal to or greater than 0.55.
Claim 3
Dependent Claim
20 words
The process of claim 1 wherein the conditions of step (1) are maintained for a period of about 1-2 hours.
Claim 4
Dependent Claim
17 words
The process of claim 1 wherein the conditions of step (2) are maintained for about 2-4 hours.
Claim 5
Dependent Claim
24 words
The process of claim 1 wherein the conditions of step (1) are maintained until the water content of the flake is below about 0.03%.
References Cited (Backward Citations)
US3014011A
Cited
US3535285A
Cited
US3544525A
Cited
BE732266A
Cited
GB1262941A
Cited
US3586647A
Cited
US3657388A
Cited
US3544523A
Cited
US3634359A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-07-13 | 1980-01-12 | 1980-07-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-07-13 | 1984-01-12 | 1984-07-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-07-13 | 1988-01-12 | 1988-07-13 | $7700.00 | Window Closed / Lapsed |