US5980797A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus and method for molding polyester articles having low acetaldehyde content directly from the melt formation using flash tank devoltatilization
Assignee: Grupo Petrotemex SA de CV
•
Filing: 1997-10-24
•
Granted: 1999-11-09
•
Expires: 2017-10-24
Abstract
Abstract An apparatus and a method for molding of polyester articles having low acetaldehyde content directly from a melt without intermediate solidification of the molten polyester. A melt to mold process is used wherein an acetaldehyde stripping agent is mixed into a polyester melt before devolatilization in a flash tank. The devolatilized polyester is pumped out of the flash tank and injected into a mold, thus forming a shaped article. The apparatus may include one or more flash tanks in one devolatilization line, or multiple devolatilization lines may be used stemming from one main polymerization reactor. The final shaped article should contain less than 10 ppm of acetaldehyde.
Inventors
- 👤 Marcus David Shelby
- 👤 Lanney Calvin Treece
- 👤 Max Lamar Carroll, Jr.
- 👤 Stephen Weinhold
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 23:40
CPC Classifications
B; B29; B29C; B29C45/00; B29C45/17; B29C45/18; B29C45/1816; B29B; B29B17/00; B29B17/0005; B29C45/46; B29C45/58; B29C45/63; B29C48/00; B29C48/022; B29C48/25; B29C48/36; B29C48/365; B29C48/37; B29C48/375; B29C48/387; B29C48/388; B29C48/395; B29C67/00; B29C67/24; B29C67/246; C; C08; C08G; C08G63/00; C08G63/78; C08G63/785; B29C2045/1883; B29C45/53; B29C45/54; B29C2045/545; B29C48/03; B29C48/05; B29C48/07; B29K; B29K2067/00; B29K2105/00; B29K2105/0002; Y; Y02; Y02W; Y02W30/00; Y02W30/50; Y02W30/62
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
138 words
An apparatus for producing molded thermoplastic articles comprising: a) means for reacting polyester precursors and forming a molten polyester homopolymer or copolymer; b) means for flowing the molten polyester into a mixer, without intermediate solidification of the molten polyester; means for injecting an acetaldehyde stripping agent into the mixer; said mixer being capable of forming a mixture of the molten polyester and the acetaldehyde stripping agent under superatmospheric pressure; c) means for flowing the mixture through one or more dies into an upper portion of a flash tank maintained under vacuum conditions therein, said dies being capable of imparting a back pressure to the mixer; means for removing vented gases, vapors and acetaldehyde from the flash tank; and d) means for removing collected devolatilized polyester from the flash tank and injecting the devolatilized polyester into a molding apparatus.
Claim 2
Independent Claim
138 words
An apparatus for producing molded thermoplastic articles comprising: a) means for reacting polyester precursors and forming a molten polyester homopolymer or copolymer; b) means for flowing the molten polyester into a mixer, without intermediate solidification of the molten polyester; means for injecting an acetaldehyde stripping agent into the mixer; said mixer being capable of forming a mixture of the molten polyester and the acetaldehyde stripping agent under superatmospheric pressure; c) means for flowing the mixture through one or more dies into an upper portion of a flash tank maintained under vacuum conditions therein, said dies being capable of imparting a back pressure to the mixer; means for removing vented gases, vapors and acetaldehyde from the flash tank; and d) means for removing collected devolatilized polyester from the flash tank and injecting the devolatilized polyester into a molding apparatus.
Claim 3
Dependent Claim
23 words
The apparatus of claim 1 wherein the mixer comprises a static mixer, a gear pump, a single screw extruder or a multi-screw extruder.
Claim 4
Dependent Claim
19 words
The apparatus of claim 1 wherein the means (d) comprises a ram accumulator, a gear pump or an extruder.
Claim 5
Dependent Claim
17 words
The apparatus of claim 1 wherein (c) comprises a plurality of dies arranged in a manifold configuration.
Claim 6
Dependent Claim
129 words
The apparatus of claim 1 comprising means for flowing the molten polyester from step (a) into a plurality of mixers, without intermediate solidification of the molten polyester; means for injecting an acetaldehyde stripping agent into the mixers; said mixers being capable of forming mixtures of the molten polyester and the acetaldehyde stripping agent under superatmospheric pressure; d) means for flowing each of the mixtures through one or more dies into an upper portion of a plurality of flash tanks, each maintained under vacuum conditions therein, said dies being capable of imparting a back pressure to the mixers; means for removing vented gases, vapors and acetaldehyde from the flash tanks; and e) means for removing collected devolatilized polyester from the flash tanks and injecting the devolatilized polyester into molding apparatuses.
Claim 7
Dependent Claim
82 words
The apparatus of claim 1 comprising means for flowing the collected devolatilized polyester from the flash tank into at least one additional flash tank prior to injecting the devolatilized polyester into the molding apparatus, said means for flowing comprising one or more additional dies at an upper portion of said additional flash tank, which flash tanks each comprise means for maintaining the flash tank under vacuum conditions therein; and means for removing vented gases, vapors and acetaldehyde from the additional flash tank.
Claim 8
Independent Claim
136 words
A method for producing molded polyester articles comprising: a) reacting polyester precursors and forming a molten polyester homopolymer or copolymer; b) continuously flowing the molten polyester from step (a) into a mixer, without intermediate solidification of the molten polyester, and forming a mixture of the polyester and an acetaldehyde stripping agent by injecting the acetaldehyde stripping agent into the mixer and mixing the stripping agent with the molten resin under subatmospheric pressure; c) flowing the mixture, through one or more dies, into an upper portion of a flash tank maintained under vacuum conditions therein, which dies impart a back pressure to the mixer, while removing vented gases, vapors and acetaldehyde from the tank; and d) removing collected devolatilized polyester from the tank and injecting the devolatilized polyester into a molding apparatus to form molded polyester articles.
Claim 9
Independent Claim
136 words
A method for producing molded polyester articles comprising: a) reacting polyester precursors and forming a molten polyester homopolymer or copolymer; b) continuously flowing the molten polyester from step (a) into a mixer, without intermediate solidification of the molten polyester, and forming a mixture of the polyester and an acetaldehyde stripping agent by injecting the acetaldehyde stripping agent into the mixer and mixing the stripping agent with the molten resin under subatmospheric pressure; c) flowing the mixture, through one or more dies, into an upper portion of a flash tank maintained under vacuum conditions therein, which dies impart a back pressure to the mixer, while removing vented gases, vapors and acetaldehyde from the tank; and d) removing collected devolatilized polyester from the tank and injecting the devolatilized polyester into a molding apparatus to form molded polyester articles.
Claim 10
Dependent Claim
34 words
The method of claim 7 wherein an acetaldehyde reducing agent is added prior to step (b) to reduce the amount of acetaldehyde in the polyester prior to forming the mixture with the stripping agent.
Claim 11
Dependent Claim
16 words
The method of claim 8 wherein the acetaldehyde reducing agent comprises a polyamide or a polyesteramide.
Claim 12
Dependent Claim
33 words
The method of claim 7 wherein an acetaldehyde reducing agent is mixed with the devolatilized polyester after it is removed from the flash tank to further reduce amounts of acetaldehyde prior to molding.
Claim 13
Dependent Claim
16 words
The method of claim 10 wherein the acetaldehyde reducing agent comprises a polyamide or a polyesteramide.
Claim 14
Dependent Claim
30 words
The method of claim 7 wherein the stripping agent is selected from the group consisting of nitrogen, carbon dioxide, C 1 to C 4 hydrocarbons, dehumidified air, and noble gases.
Claim 15
Dependent Claim
14 words
The method of claim 7 wherein the stripping agent is nitrogen or carbon dioxide.
Claim 16
Dependent Claim
28 words
The method of claim 7 wherein the stripping agent is injected into the molten polyester in an amount of about 1.0 SCF per pound of polymer or less.
Claim 17
Dependent Claim
121 words
The method of claim 7 comprising continuously flowing the molten polyester from step (a) to a plurality of mixers, without intermediate solidification of the molten polyester, and forming mixtures of the polyester and an acetaldehyde stripping agent by injecting the acetaldehyde stripping agent into the mixers and mixing the stripping agent with the molten resin under superatmospheric pressure; c) flowing each of the mixtures through one or more dies into upper portions of flash tanks maintained under vacuum conditions therein, which dies impart a back pressure to the mixers, while removing vented gases, vapors and acetaldehyde from the flash tanks; and d) removing collected devolatilized polyester from the flash tanks and injecting the devolatilized polyester into a plurality of molding apparatuses.
Claim 18
Dependent Claim
20 words
The method of claim 7 wherein the back pressure from the dies is from about 1000 to about 3000 psi.
Claim 19
Dependent Claim
21 words
The method of claim 7 wherein the temperature of the molten polyester ranges from about 255° C. to about 290° C.
Claim 20
Dependent Claim
23 words
The method of claim 7 wherein a vacuum in the flash tank ranges from about 5 mm Hg to about 50 mm Hg.
Claim 21
Dependent Claim
69 words
The method of claim 7 comprising the step of flowing the collected devolatilized polyester into at least one additional flash tank prior to injecting the devolatilized polyester into the molding apparatus, said flowing being conducted through one or more additional dies, into an upper portion of said additional flash tank which is maintained under vacuum conditions therein, while removing vented gases, vapors and acetaldehyde from the additional flash tank.
Claim 22
Dependent Claim
19 words
The method of claim 7 comprising flowing the mixture through a plurality of dies arranged in a manifold configuration.
References Cited (Backward Citations)
US3050533A
Cited
US3458494A
Cited
US3476736A
Cited
US3470070A
Cited
US3989677A
Cited
US4294652A
Cited
US4728701A
Cited
US4734243A
Cited
EP0525748A1
Cited
US5350813A
Cited
US5380822A
Cited
US5543495A
Cited
DE19503053A1
Cited
US5656221A
Cited
US5656719A
Cited
US5597891A
Cited
US5648032A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2002-11-08 | 2003-05-10 | 2003-11-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-11-08 | 2007-05-10 | 2007-11-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-11-08 | 2011-05-10 | 2011-11-09 | $7700.00 | Window Closed / Lapsed |