US4145526A
Expired / Lapsed
US
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Process for depolymerizing hydroxycarboxylic polymers
Assignee: Solvay SA
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Filing: 1978-01-09
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Granted: 1979-03-20
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Expires: 1998-01-09
Abstract
Abstract Process for obtaining hydroxycarboxylic polymers of reduced molecular weight from corresponding polymers of higher molecular weight, comprising heating the polymer of higher molecular weight in a gaseous medium to a temperature of between 60° and 240° C.
Inventors
- 👤 Noel Vanlautem
- 👤 Jacques Gilain
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 16:50
CPC Classifications
C; C08; C08F; C08F8/00; C08F8/50; Y; Y10; Y10S; Y10S264/00; Y10S264/51; Y10S526/00; Y10S526/933
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
123 words
Process for obtaining a hydroxycarboxylic polymer of reduced molecular weight from a corresponding polymer of higher molecular weight, the hydroxycarboxylic polymer containing monomer units of the formula ##STR3## in which R 1 and R 2 represent hydrogen or an alkyl group containing from 1 to 3 carbon atoms which can be substituted by a hydroxyl group or by a halogen atom, and R 1 and R 2 can be identical or different, and where M represents hydrogen, an alkali metal atom or an ammonium group comprising heating the said polymer of higher molecular weight in a gaseous medium to a temperature of between 60° and 240° C., said polymer of higher molecular weight having a Flory average molecular weight greater than about 3,000.
Claim 2
Dependent Claim
123 words
Process for obtaining a hydroxycarboxylic polymer of reduced molecular weight from a corresponding polymer of higher molecular weight, the hydroxycarboxylic polymer containing monomer units of the formula ##STR3## in which R 1 and R 2 represent hydrogen or an alkyl group containing from 1 to 3 carbon atoms which can be substituted by a hydroxyl group or by a halogen atom, and R 1 and R 2 can be identical or different, and where M represents hydrogen, an alkali metal atom or an ammonium group comprising heating the said polymer of higher molecular weight in a gaseous medium to a temperature of between 60° and 240° C., said polymer of higher molecular weight having a Flory average molecular weight greater than about 3,000.
Claim 3
Dependent Claim
11 words
Process according to claim 1, wherein M represents a sodium atom.
Claim 4
Dependent Claim
12 words
Process according to claim 1, wherein the hydroxycarboxylic polymer is a homopolymer.
Claim 5
Dependent Claim
12 words
Process according to claim 3, wherein the hydroxycarboxylic polymer is sodium poly-alpha-hydroxy-acrylate.
Claim 6
Dependent Claim
23 words
Process according to claim 1, wherein the gaseous medium contains a gas selected from the group consisting of air and the inert gases.
Claim 7
Dependent Claim
11 words
Process according to claim 5, wherein the gaseous medium contains nitrogen.
Claim 8
Dependent Claim
11 words
Process according to claim 5, wherein the gaseous medium contains air.
Claim 9
Dependent Claim
22 words
Process according to claim 1, wherein the heating is carried out under a pressure of between 0.001 and 5 kg/cm 2 .
Claim 10
Dependent Claim
24 words
Process according to claim 1, wherein the temperature to which the polymer of higher molecular weight is heated is between 70° and 200° C.
Claim 11
Dependent Claim
16 words
Process according to claim 1, wherein the heating time is between 10 minutes and 10 days.
Claim 12
Dependent Claim
23 words
Process according to claim 1, wherein the Flory average molecular weight of the polymer of higher molecular weight is between 5,000 and 800,000.
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) | 1982-03-19 | 1982-09-18 | 1983-03-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-03-19 | 1986-09-18 | 1987-03-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-03-19 | 1990-09-18 | 1991-03-20 | $7700.00 | Window Closed / Lapsed |