Patent US3865628A successfully refreshed from Google Patents.
US3865628A
Expired / Lapsed
US
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Removal of polymer residue from surfaces of processing equipment
Assignee: ENCLEAN SPECIALTY CHEMICALS Inc ("ENCLEAN") A CORP OF DE
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Filing: 1973-02-26
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Granted: 1975-02-11
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Expires: 1993-02-26
Abstract
Abstract Polymer residue is removed from the surfaces of processing equipment used in the manufacture of terephthalate polyesters by contacting the surfaces with an aqueous solution containing at least 35% by weight potassium hydroxide and, optionally, a chelating agent and a surfactant; the solution contacting the residue at at least 180* F. The equipment is subsequently flushed with water at at least 160* F.
Inventors
- 👤 Joseph W Callahan
- 👤 Charles A Landry
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 09:05
CPC Classifications
C; C09; C09D; C09D9/00
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
100 words
A METHOD FOR REMOVING DEPOSITED POLYMER RESIDUE FROM EQUIPMENT USED IN THE MANUFACTURE OF TEREPHTHALATE POLYESTER RESIN WHICH CONSISTS ESSENTIALLY OF: A. CONTACTING SAID POLYMER RESIDUE WITH AN AQUEOUS SOLUTION CONTAINING AT LEAST ABOUT 35% BY WEIGHT POTASSIUM HYDROXIDE, UP TO ABOUT 7.0% BY WEIGHT OF A CHELATING AGENT, AND UP TO ABOUT 1.5% BY WEIGHT OF A SURFACTANT STABLE IN SAID POTASSIUM HYDROXIDE SOLUTION CONTACTING SAID RESIDUE AT A USED; SAID AQUEOUS SOLUTION CONTACTING SAID RESIDUE AT A TEMPERATURE OF AT LEAST ABOUT 180*F; AND B. FLUSHING THE EQUIPMENT WITH WATER AT A TEMPERATURE OF A LEAST ABOUT 160*F.
Claim 2
Independent Claim
100 words
A METHOD FOR REMOVING DEPOSITED POLYMER RESIDUE FROM EQUIPMENT USED IN THE MANUFACTURE OF TEREPHTHALATE POLYESTER RESIN WHICH CONSISTS ESSENTIALLY OF: A. CONTACTING SAID POLYMER RESIDUE WITH AN AQUEOUS SOLUTION CONTAINING AT LEAST ABOUT 35% BY WEIGHT POTASSIUM HYDROXIDE, UP TO ABOUT 7.0% BY WEIGHT OF A CHELATING AGENT, AND UP TO ABOUT 1.5% BY WEIGHT OF A SURFACTANT STABLE IN SAID POTASSIUM HYDROXIDE SOLUTION CONTACTING SAID RESIDUE AT A USED; SAID AQUEOUS SOLUTION CONTACTING SAID RESIDUE AT A TEMPERATURE OF AT LEAST ABOUT 180*F; AND B. FLUSHING THE EQUIPMENT WITH WATER AT A TEMPERATURE OF A LEAST ABOUT 160*F.
Claim 3
Dependent Claim
25 words
The method of claim 1, wherein the aqueous solution and the flush water are continuously circulated through the equipment wherein the polymer residue is deposited.
Claim 4
Dependent Claim
22 words
The method of claim 2, wherein the solution is circulated at a temperature of from about 195* F to about 210* F.
Claim 5
Dependent Claim
23 words
The method of claim 3, wherein the aqueous treating solution contains from about 2.5% to about 7.0% by weight of a chelating agent.
Claim 6
Dependent Claim
27 words
The method of claim 4, wherein the aqueous treating solution contains from about 0.5% to about 1.5% by weight of a surfactant stable in said aqueous solution.
Claim 7
Dependent Claim
62 words
The method of claim 5, wherein the aqueous solution consists essentially of from about 40% to about 45% by weight potassium hydroxide and from about 4.5% to about 5.5% by weight of the chelating agent with the balance being water, and, further, the water used in the flushing step is at a temperature of from about 160* F to about 210* F.
Claim 8
Dependent Claim
12 words
The method of claim 6, wherein the chelating agent is sodium gluconate.
Claim 9
Dependent Claim
63 words
The method of claim 1, wherein the aqueous solution consists essentially of from about 35% by weight to about 55% by weight potassium hydroxide, from about 2.5% by weight to about 7.0% by weight of a chelating agent and from about 0.5% by weight to about 1.5% by weight of a surfactant stable in the aqueous solution at the temperature used for cleaning.
Claim 10
Dependent Claim
12 words
The method of claim 8, wherein the chelating agent is sodium gluconate.
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) | 1978-02-10 | 1978-08-12 | 1979-02-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-10 | 1982-08-12 | 1983-02-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-10 | 1986-08-12 | 1987-02-11 | $7700.00 | Window Closed / Lapsed |