Patent US4248996A successfully refreshed from Google Patents.
US4248996A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Preparation of linear high molecular weight saturated polyesters
Assignee: BASF SE
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Filing: 1979-02-28
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Granted: 1981-02-03
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Expires: 1999-02-28
Abstract
Abstract A process for the preparation of high molecular weight linear saturated polyesters derived from dicarboxylic acids or their ester-forming derivatives and aliphatic and/or cycloaliphatic diols, comprising the condensation of polyester precondensates having a relative viscosity of from 1.05 to 1.15 at from 220° to 280° C. under reduced pressure, wherein (a) the condensation is first started with from 70 to 95 percent by weight of the polyester precondensate and (b) after from 10 to 50% of the total condensation time the remaining 5 to 30 percent by weight of the polyester precondensate are added to the polyester melt undergoing condensation in accordance with (a), and the condensation is taken to completion.
Inventors
- 👤 Hans-Josef Sterzel
- 👤 Franz Schmidt
- 👤 Hans Pirzer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 20:12
CPC Classifications
C; C08; C08G; C08G63/00; C08G63/78
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
111 words
A process for the preparation of high molecular weight linear saturated polyesters derived from dicarboxylic acids or their ester-forming derivatives and aliphatic and/or cycloaliphatic diols, comprising the condensation of polyester precondensates having a relative vicosity of from 1.05 to 1.15 at from 220° to 280° C. under reduced pressure, wherein (a) the condensation is first started with from 70 to 90 percent by weight of the polyester precondensate and (b) after from 10 to 50% of the total condensation time the remaining 5 to 30 percent by weight of the polyester precondensate are added to the polyester melt undergoing condensation in accordance with (a), and the condensation is taken to completion.
Claim 2
Dependent Claim
111 words
A process for the preparation of high molecular weight linear saturated polyesters derived from dicarboxylic acids or their ester-forming derivatives and aliphatic and/or cycloaliphatic diols, comprising the condensation of polyester precondensates having a relative vicosity of from 1.05 to 1.15 at from 220° to 280° C. under reduced pressure, wherein (a) the condensation is first started with from 70 to 90 percent by weight of the polyester precondensate and (b) after from 10 to 50% of the total condensation time the remaining 5 to 30 percent by weight of the polyester precondensate are added to the polyester melt undergoing condensation in accordance with (a), and the condensation is taken to completion.
Claim 3
Dependent Claim
32 words
The process of claim 1, wherein the polyester melt undergoing condensation has a relative viscosity of from 1.25 to 1.53 at the time of addition of the remaining proportion of polyester precondensate.
Claim 4
Dependent Claim
24 words
The process of claim 1, wherein the remaining proportion of polyester precondensate is added after from 20 to 35% of the total condensation time.
Claim 5
Dependent Claim
22 words
The process of claim 1, wherein the condensation is started with from 75 to 90 percent by weight of the polyester precondensate.
Claim 6
Dependent Claim
22 words
The process of claim 1, wherein a polyester precondensate which contains at least 50 mole percent of polybutylene terephthalate units is used.
Claim 7
Dependent Claim
27 words
The process of claim 1, wherein a polyester precondensate which contains from 70 to 100 mole percent of polybutylene terephthalate units is used as the starting material.
References Cited (Backward Citations)
US4138544A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-02-03 | 1984-08-04 | 1985-02-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-02-03 | 1988-08-04 | 1989-02-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-02-03 | 1992-08-04 | 1993-02-03 | $7700.00 | Window Closed / Lapsed |