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Patent US4466867A successfully refreshed from Google Patents.
US4466867A
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Production of blue iron hexacyanoferrate-III pigments
Assignee: BASF SE
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Filing: 1983-02-18
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Granted: 1984-08-21
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Expires: 2003-02-18
Abstract
Abstract Blue iron hexacyanoferrate-III pigments are produced by a process wherein complex iron-II hexacyanoferrate-II (Berlin white) is prepared by electrolysis of an aqueous catholyte solution containing (a) an iron-II salt, (b) an alkali metal salt, an ammonium salt or a mixture of these, and (c) hydrogen cyanide, in an electrolysis cell in which the anode chamber and cathode chamber are separated by an ion exchange membrane, using an electrically conductive aqueous liquid in the anode chamber, and the iron-II hexacyanoferrate-II obtained is then converted to the blue pigment. The process gives Berlin white, which is substantially free from salt, in high yield and high purity. Pollution caused by the process is very low, since only a small amount of salt is produced. Compared with the corresponding blue pigments produced by prior art processes, the pigments obtained give purer colorations with better gloss, and are of higher color strength.
Inventors
- 👤 Wolfgang Habermann
- 👤 Peter Hammes
- 👤 Joachim Felger
- 👤 Karl-Ludwig Hock
- 👤 Friedrich Brunnmueller
- 👤 Helmut Knittel
- 👤 Joachim Kranz
- 👤 Rolf Schneider
- 👤 Peter Thoma
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 07:31
CPC Classifications
C; C25; C25B; C25B1/00; C09; C09C; C09C1/00; C09C1/22; C09C1/26; C25B1/01; C01; C01P; C01P2006/00; C01P2006/80
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
103 words
A process for the production of a blue iron hexacyanoferrate-III pigment, wherein iron-II hexacyanoferrate-II (Berlin white) is prepared, in an electrolysis cell whose anode chamber and cathode chamber are separated by an ion exchange membrane, by electrolysis of an aqueous solution containing (a) an iron-II salt, (b) an alkali metal salt, an ammonium salt or a mixture of these, and (c) hydrogen cyanide, at a pH of from 0.5 to 6, as catholyte in the cathode chamber, and of an electrically conductive, aqueous solution in the anode chamber, the iron-II hexacyanoferrate-II is oxidized to the iron hexacyanoferrate-III pigment, and the latter is isolated.
Claim 2
Dependent Claim
103 words
A process for the production of a blue iron hexacyanoferrate-III pigment, wherein iron-II hexacyanoferrate-II (Berlin white) is prepared, in an electrolysis cell whose anode chamber and cathode chamber are separated by an ion exchange membrane, by electrolysis of an aqueous solution containing (a) an iron-II salt, (b) an alkali metal salt, an ammonium salt or a mixture of these, and (c) hydrogen cyanide, at a pH of from 0.5 to 6, as catholyte in the cathode chamber, and of an electrically conductive, aqueous solution in the anode chamber, the iron-II hexacyanoferrate-II is oxidized to the iron hexacyanoferrate-III pigment, and the latter is isolated.
Claim 3
Dependent Claim
18 words
A process as claimed in claim 1, wherein the catholyte has a pH of from 2 to 4.
Claim 4
Dependent Claim
33 words
A process as claimed in claim 2, wherein not less than 1 equivalent of (b) and not less than 6 moles of (c) are used per 2 moles of (a) in the catholyte.
Claim 5
Dependent Claim
28 words
A process as claimed in claim 3, wherein the catholyte contains (a) and (b) in the form of the sulfates, hydrogen sulfates or chlorides, or mixtures of these.
Claim 6
Dependent Claim
19 words
A process as claimed in claim 4, wherein the electrolysis is carried out at from 20° to 60° C.
Claim 7
Dependent Claim
27 words
A process as claimed in claim 6, wherein (b) is present in the form of one or more sodium or potassium salts or of a mixture thereof.
Claim 8
Dependent Claim
19 words
A process as claimed in claim 6, wherein the electrolysis is carried out at from 20° to 60° C.
Claim 9
Dependent Claim
27 words
A process as claimed in claim 7, wherein the complex iron-II hexacyanoferrate-II is oxidized with air or oxygen, at pH>8 and at from 20° to 50° C.
Claim 10
Dependent Claim
50 words
A process as claimed in claim 6, wherein the oxidation of the complex iron-II hexacyanoferrate-II is carried out with air, oxygen, hydrogen peroxide or a peroxydisulfate, or is effected electrochemically, at from 20° to 95° C. and at a pH of from 0 to 4, preferably from 0 to 2.5.
Claim 11
Dependent Claim
19 words
A process as claimed in claim 6, wherein the electrolysis is carried out at from 20° to 60° C.
Claim 12
Dependent Claim
33 words
A process as claimed in claim 1, wherein not less than 1 equivalent of (b) and not less than 6 moles of (c) are used per 2 moles of (a) in the catholyte.
Claim 13
Dependent Claim
28 words
A process as claimed in claim 1, wherein the catholyte contains (a) and (b) in the form of the sulfates, hydrogen sulfates, or chlorides, or mixtures of these.
Claim 14
Dependent Claim
27 words
A process as claimed in claim 12, wherein (b) is present in the form of one or more sodium or potassium salts or of a mixture thereof.
Claim 15
Dependent Claim
28 words
A process as claimed in claim 1, wherein (b) is present in the form of one or more sodium salts, one or more potassium salts, or mixtures thereof.
Claim 16
Dependent Claim
19 words
A process as claimed in claim 1, wherein the electrolysis is carried out at from 20° to 60° C.
Claim 17
Dependent Claim
16 words
A process as claimed in claim 1, wherein electrolysis of the catholyte is carried out continuously.
Claim 18
Dependent Claim
52 words
A process as claimed in claim 1, wherein the oxidation of the complex iron-II hexacyanoferrate-II is carried out with air, oxygen, a chlorate, chlorine, hydrogen peroxide or a peroxydisulfate, or is effected electrochemically, at from 20° to 95° C. and at a pH from 0 to 4, preferably from 0 to 2.5.
Claim 19
Dependent Claim
27 words
A process as claimed in claim 1, wherein the complex iron-II hexacyanoferrate-II is oxidized with air or oxygen, at pH>8 and at from 20° to 50° C.
Claim 20
Dependent Claim
123 words
A process for the preparation of a blue iron hexacyanoferrate-III pigment, wherein iron-II hexacyanoferrate-II (Berlin white) is prepared, in an electrolysis cell whose anode chamber and cathode chamber are separated by an ion exchange membrane, by electrolysis of an aqueous solution containing (a) an iron-II salt, (b) a sodium, potassium or ammonium salt, or a mixture of these, and (c) hydrogen cyanide, in a ratio corresponding to 1.3-2.5 equivalents of (b) and 6.1-7.5 moles of (c) per 2 moles of (a), at a pH of from 2 to 4 as catholyte in the cathode chamber, and of an electrically conductive, aqueous solution in the anode chamber, the resulting complex iron-II hexacyanoferrate-II is oxidized to the iron hexacyanoferate-III pigment, and the latter is isolated.
Claim 21
Dependent Claim
123 words
A process for the preparation of a blue iron hexacyanoferrate-III pigment, wherein iron-II hexacyanoferrate-II (Berlin white) is prepared, in an electrolysis cell whose anode chamber and cathode chamber are separated by an ion exchange membrane, by electrolysis of an aqueous solution containing (a) an iron-II salt, (b) a sodium, potassium or ammonium salt, or a mixture of these, and (c) hydrogen cyanide, in a ratio corresponding to 1.3-2.5 equivalents of (b) and 6.1-7.5 moles of (c) per 2 moles of (a), at a pH of from 2 to 4 as catholyte in the cathode chamber, and of an electrically conductive, aqueous solution in the anode chamber, the resulting complex iron-II hexacyanoferrate-II is oxidized to the iron hexacyanoferate-III pigment, and the latter is isolated.
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) | 1987-08-21 | 1988-02-20 | 1988-08-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-08-21 | 1992-02-20 | 1992-08-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-08-21 | 1996-02-20 | 1996-08-21 | $7700.00 | Window Closed / Lapsed |