US3930979A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Porous diaphragms
Assignee: Imperial Chemical Industries Ltd
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Filing: 1974-06-27
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Granted: 1976-01-06
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Expires: 1994-06-27
Abstract
Abstract A process for the manufacture of a porous diaphragm of a synthetic material, especially polytetrafluoroethylene, which comprises forming a sheet of the synthetic material in admixture with a solid particulate additive (eg starch) to be removed therefrom, introducing said sheet into a cell, and removing the solid particulate additive from the sheet by treating the sheet in situ in the cell with an acid (eg hydrochloric acid) containing a corrosion inhibitor (eg propargyl alcohol). The porous diaphragms are especially suitable for use in diaphragm cells for the production of chlorine from sodium chloride brine.
Inventors
- 👤 Christopher Vallance
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 18:35
CPC Classifications
H; H01; H01J; H01J31/00; H01J31/08; H01J31/26; H01J31/28; H01J31/34; H01J31/36; C; C25; C25B; C25B13/00; C25B13/04; C25B13/08
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
70 words
A process for the manufacture of a porous diaphragm of a synthetic material for use in an electrolytic cell which comprises forming a sheet of the synthetic material in admixture with a solid particulate additive to be removed therefrom, introducing said sheet into an electrolytic cell, and removing solid particulate additive from the sheet in situ in the cell by treating the sheet with an acid containing a corrosion inhibitor.
Claim 2
Dependent Claim
70 words
A process for the manufacture of a porous diaphragm of a synthetic material for use in an electrolytic cell which comprises forming a sheet of the synthetic material in admixture with a solid particulate additive to be removed therefrom, introducing said sheet into an electrolytic cell, and removing solid particulate additive from the sheet in situ in the cell by treating the sheet with an acid containing a corrosion inhibitor.
Claim 3
Dependent Claim
14 words
A process as claimed in claim 1 wherein the acid is a mineral acid.
Claim 4
Dependent Claim
16 words
A process as claimed in claim 2 wherein the acid is nitric, sulphuric or hydrochloric acid.
Claim 5
Dependent Claim
18 words
A process as claimed in claim 3 wherein the acid is 16 to 18% by weight hydrochloric acid.
Claim 6
Dependent Claim
14 words
A process as claimed in claim 1 wherein the acid is an alkanoic acid.
Claim 7
Dependent Claim
13 words
A process as claimed in claim 5 wherein the acid is acetic acid.
Claim 8
Dependent Claim
14 words
A process as claimed in claim 1 wherein the corrosion inhibitor is propargyl alcohol.
Claim 9
Dependent Claim
13 words
A process as claimed in claim 1 wherein the corrosion inhibitor is thiourea.
Claim 10
Dependent Claim
16 words
A process as claimed in claim 1 wherein the corrosion inhibitor is an alkali metal thiocyanate.
Claim 11
Dependent Claim
14 words
A process as claimed in claim 9 wherein the corrosion inhibitor is potassium thiocyanate.
Claim 12
Dependent Claim
29 words
A process as claimed in claim 1 wherein the proportion of corrosion inhibitor is in the range 0.01 to 5.0 percent by volume based on the volume of acid.
Claim 13
Dependent Claim
24 words
A process as claimed in claim 11 wherein the proportion of corrosion inhibitor is 0.1 percent by volume based on the volume of acid.
Claim 14
Dependent Claim
14 words
A process as claimed in claim 1, which is carried out at ambient temperature.
Claim 15
Dependent Claim
20 words
A process as claimed in claim 1, which is carried out at a temperature in the range 50° to 60°C.
Claim 16
Dependent Claim
13 words
A process as claimed in claim 1 wherein the synthetic material is polytetrafluoroethylene.
Claim 17
Dependent Claim
23 words
A process as claimed in claim 1 wherein the solid particulate additive is starch, cellulose, cellulose acetate, or a water-insoluble base or carbonate.
Claim 18
Dependent Claim
22 words
A process as claimed in claim 16 wherein the removable solid particulate additive is maize starch and/or potato starch or calcium carbonate.
Claim 19
Dependent Claim
18 words
An electrolytic cell fitted with a porous diaphragm, which porous diaphragm is produced in accordance with claim 1.
Claim 20
Dependent Claim
17 words
An electrolytic cell as claimed in claim 18 for the electrolysis of an alkali metal chloride brine.
Claim 21
Dependent Claim
15 words
An electrolytic cell as claimed in claim 18 for the electrolysis of sodium chloride brine.
References Cited (Backward Citations)
US2542527A
Cited
DE1174973B
Cited
DE1144357B
Cited
US3257334A
Cited
US3282875A
Cited
GB1124362A
Cited
US3718561A
Cited
DE2139646A1
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-01-05 | 1979-07-07 | 1980-01-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-01-05 | 1983-07-07 | 1984-01-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-01-05 | 1987-07-07 | 1988-01-06 | $7700.00 | Window Closed / Lapsed |