Patent US4670519A successfully refreshed from Google Patents.
US4670519A
Expired / Lapsed
US
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Narrowing the molecular weight distribution of polytetrahydrofuran
Assignee: BASF SE
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Filing: 1986-01-29
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Granted: 1987-06-02
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Expires: 2006-01-29
Abstract
Abstract The molecular weight distribution of polytetrahydrofuran which has been obtained by polymerization of tetrahydrofuran using a cationic catalyst is narrowed by a process in which the polytetrahydrofuran is heated at from 80° to 280° C. in the presence of a bleaching earth or a zeolite as a catalyst.
Inventors
- 👤 Herbert Mueller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 06:17
CPC Classifications
C; C08; C08G; C08G65/00; C08G65/02; C08G65/04; C08G65/06; C08G65/16; C08G65/20; C08G65/30; C08G2650/00; C08G2650/02; C08G2650/12; C08G2650/28; C08G2650/34
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
134 words
A process for narrowing the molecular weight distribution of polytetrahydrofuran which has been obtained by polymerization of tetrahydrofuran using a cationic catalyst, which method comprises: heating the polytetrahydrofuran for depolymerization in the presence of a bleaching earth or a zeolite as a catalyst while simultaneously distilling off tetrahydrofuran, at a temperature from 80° to 280° C., said initial polytetrahydrofuran to be depolymerized having a number average molecular weight of from 650 to 3000, a molecular weight distribution (Mw/Mn) of from 1.5 to 4 and a viscosity of from 1 to 70 poise (at 40° C.), and said heating being carried out for a period of time sufficient only to depolymerize from 10 to 40% by weight of the initial polytetrahydrofuran and to produce a reduced molecular weight distribution (Mw/Mn) of from 1.2 to 2.5.
Claim 2
Dependent Claim
134 words
A process for narrowing the molecular weight distribution of polytetrahydrofuran which has been obtained by polymerization of tetrahydrofuran using a cationic catalyst, which method comprises: heating the polytetrahydrofuran for depolymerization in the presence of a bleaching earth or a zeolite as a catalyst while simultaneously distilling off tetrahydrofuran, at a temperature from 80° to 280° C., said initial polytetrahydrofuran to be depolymerized having a number average molecular weight of from 650 to 3000, a molecular weight distribution (Mw/Mn) of from 1.5 to 4 and a viscosity of from 1 to 70 poise (at 40° C.), and said heating being carried out for a period of time sufficient only to depolymerize from 10 to 40% by weight of the initial polytetrahydrofuran and to produce a reduced molecular weight distribution (Mw/Mn) of from 1.2 to 2.5.
Claim 3
Dependent Claim
20 words
A process as claimed in claim 1, wherein the polytetrahydrofuran is heated at a temperature from 100° to 180° C.
Claim 4
Dependent Claim
20 words
A process as claimed in claim 1, wherein the narrowing procedure is carried out continuously over a fixed catalyst bed.
Claim 5
Dependent Claim
22 words
A process as claimed in claim 1, wherein the narrowing procedure is carried out under a pressure from 1 to 100 bar.
Claim 6
Dependent Claim
31 words
A process as claimed in claim 1, wherein the heating to narrow the molecular weight distribution is carried out until 15 to 25% by weight of the initial polytetrahydrofuran is depolymerized.
Claim 7
Dependent Claim
31 words
A process as claimed in claim 1, wherein the depolymerization catalyst is used in an amount based on the total batch of the polymer of from 0.01 to 10% by weight.
Claim 8
Dependent Claim
31 words
A process as claimed in claim 1, wherein the depolymerization catalyst is used in an amount based on the total batch of the polymer, of from 0.3 to 5% by weight.
Claim 9
Dependent Claim
37 words
A process as claimed in claim 1, wherein the depolymerization process is carried out at a temperature up to 160° C. at atmospheric pressure and up to 200° C. at an elevated pressure up to 70 bar.
Claim 10
Dependent Claim
18 words
A process as claimed in claim 1, wherein the catalyst used for the depolymerization is a bleaching earth.
Claim 11
Dependent Claim
17 words
A process as claimed in claim 1, wherein the catalyst used for the depolymerization is a zeolite.
Claim 12
Dependent Claim
23 words
A process as claimed in claim 1, wherein the polymer of reduced molecular weight distribution is recovered substantially free of the tetrahydrofuran monomer.
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) | 1990-06-01 | 1990-12-01 | 1991-06-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-01 | 1994-12-01 | 1995-06-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-01 | 1998-12-01 | 1999-06-02 | $7700.00 | Window Closed / Lapsed |