US5597891A
Expired / Lapsed
US
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Process for producing polyester articles having low acetaldehyde content
Assignee: Grupo Petrotemex SA de CV
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Filing: 1995-08-01
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Granted: 1997-01-28
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Expires: 2015-08-01
Abstract
Abstract Disclosed is a process for removing acetaldehyde from polyester which comprises the steps of a) transporting molten polyester to a vented, continuous screw conveyor having a polymer compression zone, b) rotating the screw of said conveyor so as to compress and convey through the extruder the molten polymer for a time of less than 15 minutes and at a temperature of less than 300° C., c) simultaneously with step b), flowing a purge agent into and out of said extruder to thereby remove volatile impurities and avoid appreciable build-up of acetaldehyde, and d) conveying the devolatized polymer melt to a mold wherein an article of manufacture is formed.
Inventors
- 👤 Gregory W. Nelson
- 👤 Clinton Cherry
- 👤 Eric G. Olsen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 08:18
CPC Classifications
C; C08; C08G; C08G63/00; C08G63/88; C08G63/90; B; B29; B29B; B29B7/00; B29B7/30; B29B7/34; B29B7/38; B29B7/40; B29B7/42; B29B7/46; B29B7/48; B29B7/80; B29B7/84; B29B7/845; B29B7/86; B29C; B29C48/00; B29C48/25; B29C48/36; B29C48/50; B29C48/505; B29C48/53; B29C48/76; B29C48/765; B29C48/766; B29C48/767; B29C48/03; B29K; B29K2105/00; B29K2105/0002
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
125 words
A process for removing acetaldehyde from polyester derived from components comprising at least one dicarboxylic acid and at least one glycol which comprises the steps of a) transporting molten polyester to a vented, continuous screw conveyor having a polymer compression zone, b) rotating the screw of said conveyor so as to compress and convey through the extruder the molten polymer for a time of less than 15 minutes and at a temperature of less than 300° C., c) simultaneously with step b), flowing a purge agent into and out of said extruder to thereby remove volatile impurities from said molten polyester and avoid appreciable build-up of acetaldehyde, and d) conveying the devolatized polymer melt to a forming device wherein an article of manufacture is formed.
Claim 2
Dependent Claim
125 words
A process for removing acetaldehyde from polyester derived from components comprising at least one dicarboxylic acid and at least one glycol which comprises the steps of a) transporting molten polyester to a vented, continuous screw conveyor having a polymer compression zone, b) rotating the screw of said conveyor so as to compress and convey through the extruder the molten polymer for a time of less than 15 minutes and at a temperature of less than 300° C., c) simultaneously with step b), flowing a purge agent into and out of said extruder to thereby remove volatile impurities from said molten polyester and avoid appreciable build-up of acetaldehyde, and d) conveying the devolatized polymer melt to a forming device wherein an article of manufacture is formed.
Claim 3
Dependent Claim
17 words
Process according to claim 1 wherein the polyester from step a) has an I.V. of about 0.50-0.85.
Claim 4
Dependent Claim
14 words
Process according to claim 1 wherein the conveyer in step b) is an extruder.
Claim 5
Dependent Claim
19 words
Process according to claim 1 wherein the polyester has a final residual acetaldehyde content of less than <15 ppm.
Claim 6
Dependent Claim
17 words
Process according to claim 1 wherein at least 80 mol % said dicarboxylic acid is terephthalic acid.
Claim 7
Dependent Claim
17 words
Process according to claim 1 wherein at least 80 mol % of said glycol is ethylene glycol.
Claim 8
Dependent Claim
16 words
Process according to claim 1 wherein said glycol is a mixture of ethylene glycol and cyclohexane-dimethanol.
Claim 9
Dependent Claim
30 words
Process according to claim 1 wherein said acid is terephthalic acid and said glycol is a mixture of about 60-99 mol % ethylene glycol and about 40-1 mol % cyclohexanedimethanol.
Claim 10
Dependent Claim
17 words
Shaped, extruded or molded polymeric articles having low acetaldehyde content produced by the process of claim 1.
Claim 11
Dependent Claim
28 words
Process of claim 1 where the temperature of the polymer in the devolatilization zone is held at 5° to 50° C. above the melting point of said polyester.
Claim 12
Dependent Claim
14 words
Process of claim 1 where the polymer is devolatilized for 5 to 600 seconds.
Claim 13
Dependent Claim
18 words
Process of claim 1 where the polymer spends from 0.1 to 15 minutes in the melt after devolatilization.
Claim 14
Dependent Claim
16 words
Process of claim 1 where the inherent viscosity of the resultant polymer is 0.55 to 0.95.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-01-28 | 2000-07-29 | 2001-01-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-01-28 | 2004-07-29 | 2005-01-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-01-28 | 2008-07-29 | 2009-01-28 | $7700.00 | Window Closed / Lapsed |