US4064112A
Expired / Lapsed
US
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Process for the continuous production of high molecular weight polyethylene terephthalate
Assignee: LL Plant Engineering AG
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Filing: 1976-04-15
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Granted: 1977-12-20
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Expires: 1996-04-15
Abstract
Abstract This invention relates to a process for the continuous production of high molecular weight polyethylene terephthalate by polycondensation in the solid phase wherein granulated, dried polyethylene terephthalate, having an intrinsic viscosity of at least 0.15, is first crystallized and is thereafter subjected to solid state polycondensation.
Inventors
- 👤 Hans Joachim Rothe
- 👤 Helmut Heinze
- 👤 Brian D. Whitehead
- 👤 Gunther Priepke
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 22:59
CPC Classifications
C; C08; C08G; C08G63/00; C08G63/78; C08G63/80
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
106 words
A process for the continuous production of high molecular weight polyethylene terephthalate by polycondensation in the solid phase from a dried, granulated polyethylene terephthalate, having an intrinsic viscosity of at least 0.15, which comprises crystallizing the granulate to a density of at least 1.390 g/cm3 under forced motion at a temperature of 220° C to 260° C under an inert gas atmosphere, passing the crystallized granulate at a constant or reduced temperature to a continuous fixed bed reactor, and, continuously polycondensing the crystallized granulate in said reactor while in contact with an inert gas stream at a temperature equivalent to, or lower than, the crystallization temperature.
Claim 2
Dependent Claim
106 words
A process for the continuous production of high molecular weight polyethylene terephthalate by polycondensation in the solid phase from a dried, granulated polyethylene terephthalate, having an intrinsic viscosity of at least 0.15, which comprises crystallizing the granulate to a density of at least 1.390 g/cm3 under forced motion at a temperature of 220° C to 260° C under an inert gas atmosphere, passing the crystallized granulate at a constant or reduced temperature to a continuous fixed bed reactor, and, continuously polycondensing the crystallized granulate in said reactor while in contact with an inert gas stream at a temperature equivalent to, or lower than, the crystallization temperature.
Claim 3
Dependent Claim
29 words
A process according to claim 1, wherein the crystallization temperature is 230° C to 245° C and the granulate is crystallized to a density of 1.403 to 1.415 g/cm3.
Claim 4
Dependent Claim
18 words
A process according to claim 1, wherein the solid state polycondensation temperature is 230° C to 245° C.
Claim 5
Dependent Claim
19 words
A process according to claim 1, wherein the granulated polyethylene terephthalate has an intrinsic viscosity of at least 0.4.
Claim 6
Dependent Claim
22 words
A process according to claim 1, wherein the granulate material has a OH to COOH end group ratio of at least 1.5:1.
Claim 7
Dependent Claim
15 words
A process according to claim 5, wherein the end group ratio is at least 3:1.
Claim 8
Dependent Claim
15 words
A process according to claim 1, wherein the crystallization time is 0.5 to 3 hours.
Claim 9
Dependent Claim
15 words
A process according to claim 7, wherein the crystallization time is 1 to 2 hours.
Claim 10
Dependent Claim
19 words
A process according to claim 1, wherein an inert gas removes reaction products from the solid state polycondensation reactor.
Claim 11
Dependent Claim
12 words
A process according to claim 9, wherein said inert gas is nitrogen.
Claim 12
Dependent Claim
55 words
A process according to claim 9, wherein the nitrogen has a water content of less than 250 mg/kg N 2 , an ethylene glycol content of less than 10 mg/kg N 2 , an oxygen content of less than 10 mg/kg N 2 and an aldehyde content of less than 1 mg/kg N 2 .
Claim 13
Dependent Claim
24 words
A process according to claim 10, wherein the weight ratio of nitrogen to crystallized granulate, in the solid state polycondensation is 0.7:1 to 3:1.
Claim 14
Dependent Claim
16 words
A process according to claim 12, wherein said nitrogen to granulate ratio is 1:1 to 2:1.
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) | 1980-12-19 | 1981-06-20 | 1981-12-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-12-19 | 1985-06-20 | 1985-12-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-12-19 | 1989-06-20 | 1989-12-20 | $7700.00 | Window Closed / Lapsed |