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US4140538A
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Iron oxide-based anti-corrosion pigments
Assignee: Bayer AG
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Filing: 1976-08-11
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Granted: 1979-02-20
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Expires: 1996-08-11
Abstract
Abstract An anti-corrosion pigment comprising about 30 to 70 mole % of an oxide of at least one metal selected from the group consisting of magnesium, calcium and zinc, about 70 to 30 mole % of Fe 2 O 3 , and up to about 20 mole % of Cr 2 O 3 , the pigment having a specific surface of about 1 to 30 m 2 /g and exhibiting a weight loss of less than about 0.05% per gram of pigment by the Thomson corrosion test, is produced by calcining the corresponding metal oxides. The temperature is about 200 to 650° C. in the absence of chromium and about 200 to 900° C. when chromium is present.
Inventors
- 👤 Franz Hund
- 👤 Gunter Linde
- 👤 Peter Kresse
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 16:17
CPC Classifications
C; C09; C09C; C09C1/00; C09C1/22; C09C1/24; C09C1/34; C01; C01P; C01P2004/00; C01P2004/80; C01P2004/82; C01P2006/00; C01P2006/12
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
84 words
A process for the production of an anti-corrosion pigment, comprising about 30 to 70 mole % of an oxide of at least one metal selected from the group consisting of magnesium, calcium and zinc, about 70 to 30 mole % of Fe 2 O 3 , and about 0.1 to 20 mole % of Cr 2 O 3 , which comprises calcining the corresponding metal oxides or starting materials which yield metal oxides upon calcination at a temperature of about 200° to 900° C.
Claim 2
Dependent Claim
84 words
A process for the production of an anti-corrosion pigment, comprising about 30 to 70 mole % of an oxide of at least one metal selected from the group consisting of magnesium, calcium and zinc, about 70 to 30 mole % of Fe 2 O 3 , and about 0.1 to 20 mole % of Cr 2 O 3 , which comprises calcining the corresponding metal oxides or starting materials which yield metal oxides upon calcination at a temperature of about 200° to 900° C.
Claim 3
Dependent Claim
17 words
A process as claimed in claim 1, wherein calcination is effected at about 250° to 800° C.
Claim 4
Dependent Claim
17 words
A process as claimed in claim 1, wherein calcination is effected at about 300° to 650° C.
Claim 5
Dependent Claim
38 words
A process as claimed in claim 1, wherein the metal selected from the group consisting of magnesium, calcium, and zinc is initially present as a hydroxide, hydroxy salt, carbonate, basic carbonate, nitrate, chloride, sulfate, formate, acetate or oxalate.
Claim 6
Dependent Claim
42 words
A process as claimed in claim 1 wherein the iron is initially present as an Fe(II) oxide, hydroxide, hydroxy salt, carbonate, basic carbonate, nitrate, chloride, sulfate, formate, acetate or oxalate and calcination is carried out in the presence of an oxygen-containing gas.
Claim 7
Dependent Claim
35 words
A process as claimed in claim 1, wherein the iron is initially present as a Fe(III) alpha-, betha-, or gamma-oxide, alpha-, betha-, gamma- or delta-oxide hydroxide, amorphous hydroxide, sulfate, nitrate, chloride, formate, oxalate or acetate.
Claim 8
Dependent Claim
21 words
A process as claimed in claim 1, wherein the chromium is initially present as a Cr(III) oxide aquate or amorphous hydroxide.
Claim 9
Dependent Claim
25 words
A process as claimed in claim 1, wherein a mixed hydroxide or oxide hydroxide of Fe(III) and Cr(III) is included in the material being calcined.
Claim 10
Dependent Claim
43 words
An anti-corrosion pigment produced by the process of claim 1, the pigment having a specific surface of about 1 to 30 m 2 /g and exhibiting a weight loss of less than about 0.05% per gram of pigment by the Thomson corrosion test.
Claim 11
Dependent Claim
19 words
A pigment according to claim 9 containing about 0.1 to 10 mole % of Cr 2 O 3 .
Claim 12
Dependent Claim
35 words
A pigment according to claim 9 containing about 0.2 to 5 mole % of Cr 2 O 3 and exhibiting a Thomson corrosion test weight loss of less than about 0.03% per gram of pigment.
Claim 13
Dependent Claim
16 words
A pigment according to claim 9 comprising about 30 to 70 mole % of magnesium oxide.
Claim 14
Dependent Claim
16 words
A pigment according to claim 9 comprising about 30 to 70 mole % of zinc oxide.
References Cited (Backward Citations)
US2502130A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-02-19 | 1982-08-21 | 1983-02-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-02-19 | 1986-08-21 | 1987-02-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-02-19 | 1990-08-21 | 1991-02-20 | $7700.00 | Window Closed / Lapsed |