Patent US3904685A successfully refreshed from Google Patents.
US3904685A
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Polyacrylic acid having high chelation value and its production
Assignee: Celanese Corp
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Filing: 1973-07-20
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Granted: 1975-09-09
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Expires: 1993-07-20
Abstract
Abstract Polyacrylic acid having a high chelation value is produced by polymerizing acrylic acid at elevated temperature in the presence of an alkali metal or ammonium persulfate initiator and, in a concentration of about 0.5 to 4% by weight of the acrylic acid, a chain transfer agent selected from the group consisting of alkanethiols, hydroxy alkanethiols, and carboxy alkanethiols. Preferably the chain transfer agent is present in about 1% by weight concentration and is octanethiol, butanethiol, thioglycolic acid, or 2-thioethanol.
Inventors
- 👤 Iraj Khatib Shahidi
- 👤 Jorge Alberto Blay
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 20:58
CPC Classifications
C; C11; C11D; C11D3/00; C11D3/16; C11D3/37; C11D3/3746; C11D3/3757; C11D3/3761; C08; C08F; C08F120/00; C08F120/02; C08F120/04; C08F120/06
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
67 words
THE PROCESS FOR PRODUCING A POLYACRYLIC ACID OF HIGH CHELATION VALUE AT 80% CHELATION WHICH COMPRISES POLYMERIZING ACRYLIC ACID IN AQUEOUS SOLUTION AT ELEVATED TEMPERATURE IN THE PRESENCE OF AN ALKALI METAL OR AMMONIUM PERSULFATE AS INITIATOR AND ABOUT 0.5 TO 4% BY WEIGHT OF ACRYLIC ACID OF A CHAIN TRANSFER AGENT SELECTED FROM THE GROUP CONSISTING OF AN ALKANETHIOL, A HYDROXY ALKANETHILO AND A CARBOXY ALKANETHIOL.
Claim 2
Dependent Claim
67 words
THE PROCESS FOR PRODUCING A POLYACRYLIC ACID OF HIGH CHELATION VALUE AT 80% CHELATION WHICH COMPRISES POLYMERIZING ACRYLIC ACID IN AQUEOUS SOLUTION AT ELEVATED TEMPERATURE IN THE PRESENCE OF AN ALKALI METAL OR AMMONIUM PERSULFATE AS INITIATOR AND ABOUT 0.5 TO 4% BY WEIGHT OF ACRYLIC ACID OF A CHAIN TRANSFER AGENT SELECTED FROM THE GROUP CONSISTING OF AN ALKANETHIOL, A HYDROXY ALKANETHILO AND A CARBOXY ALKANETHIOL.
Claim 3
Dependent Claim
44 words
The process of claim 1, wherein the chain transfer agent is an alkylmercaptan and is present in a concentration of about 1% by weight of the acrylic acid, and wherein the polymerization is conducted at about 95* C for about 1 to 2 hours.
Claim 4
Dependent Claim
12 words
The process of claim 2, wherein the chain transfer agent is octanethiol.
Claim 5
Dependent Claim
12 words
The process of claim 2, wherein the chain transfer agent is butanethiol.
Claim 6
Dependent Claim
13 words
The process of claim 1 wherein the chain transfer agent is thioglycolic acid.
Claim 7
Dependent Claim
12 words
The process of claim 1 wherein the chain transfer agent is 2-thioethanol.
Claim 8
Dependent Claim
42 words
Polyacrylic acid produced by the process of claim 2 and having a chelation value at 80% chelation in excess of about 500 mg CaCO3 per gram in an aqueous solution containing calcium ions in a concentration equivalent to 200 ppm of CaCO3.
References Cited (Backward Citations)
US2833745A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-08 | 1979-03-10 | 1979-09-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-08 | 1983-03-10 | 1983-09-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-08 | 1987-03-10 | 1987-09-09 | $7700.00 | Window Closed / Lapsed |