US4140539A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydrothermal process for producing dense iron oxide pigments
Assignee: Toda Kogyo Corp
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Filing: 1977-07-18
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Granted: 1979-02-20
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Expires: 1997-07-18
Abstract
Abstract An acicular to prismatic ferrimagnetic iron oxide pigment with a porosity of less than about 10% by volume, and optionally containing up to about 15% by weight of other metal oxides such as Zn or especially Co, are produced by heating a suspension of iron(III)oxide hydroxide in an autoclave to a temperature above about 100° C in the presence of at least one mono-, di- or tri-saccharide, at least one alkali metal or alkaline earth metal hydroxide or carbonate and excess water, and washing, filtering and drying the resulting pigments.
Inventors
- 👤 Franz Hund
- 👤 Gunter Buxbaum
- 👤 Lutz Leitner
- 👤 Ingo Pflugmacher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 23:15
CPC Classifications
C; C09; C09C; C09C1/00; C09C1/22; C09C1/24; G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70647; G11B5/70652; G11B5/70668; G11B5/70673; C01; C01P; C01P2002/00; C01P2002/30; C01P2006/00; C01P2006/42
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
21 words
Acicular ferrimagnetic iron oxide pigment particles with a porosity of less than about 10% by volume and of cubic spinel structure.
Claim 2
Dependent Claim
21 words
Acicular ferrimagnetic iron oxide pigment particles with a porosity of less than about 10% by volume and of cubic spinel structure.
Claim 3
Dependent Claim
19 words
An iron oxide pigment as claimed in claim 1, with a porosity of less than about 5% by volume.
Claim 4
Dependent Claim
32 words
An iron oxide pigment as claimed in claim 1, which, in addition to iron oxide, contains at least one other metal oxide in a concentration of up to about 15% by weight.
Claim 5
Dependent Claim
19 words
An iron oxide pigment as claimed in claim 3, containing about 1 to 10% by weight of cobalt oxide.
Claim 6
Dependent Claim
64 words
A process for producing an iron oxide pigment as claimed in claim 1, comprising heating a suspension of iron(III)oxide hydroxide in an autoclave to a temperature above about 100° C. in the presence of at least one mono-, di- or tri-saccharide, at least one alkali metal or alkaline earth metal hydroxide or carbonate and excess water, and washing, filtering and drying the resulting pigments.
Claim 7
Dependent Claim
22 words
A process as claimed in claim 5, wherein the iron(III)oxide hydroxide is an α-(Fe,Co)OOH or α-(Fe,Zn)OOH obtained by acid or alkaline co-precipitation.
Claim 8
Dependent Claim
23 words
A process as claimed in claim 5, wherein the saccharide is at least one of arabinose, xylose, ribose, glucose, galactose, mannose and fructose.
Claim 9
Dependent Claim
21 words
A process as claimed in claim 5, wherein the saccharide is at least one of cane sugar, lactose, maltose and raffinose.
Claim 10
Dependent Claim
23 words
A process as claimed in claim 5, wherein the suspension additionally contains about 0.01 to 2% by weight of at least one laminator.
Claim 11
Dependent Claim
20 words
A process as claimed in claim 9, wherein the laminator is at least one of polyvinyl alcohol and lignin sulphonate.
Claim 12
Dependent Claim
22 words
A process as claimed in claim 5, wherein the mixture is heated in the autoclave to a temperature above about 200° C.
Claim 13
Dependent Claim
25 words
A process as claimed in claim 5, including the further step of oxidizing the pigment at a temperature of from about 250° to 350° C.
Claim 14
Dependent Claim
80 words
A process as claimed in claim 12, wherein the iron(III)oxide hydroxide is an α-(Fe,CO)OOH or α-(Fe,Zn)OOH obtained by acid or alkaline co-precipitation, the saccharide is at least one of arabinose, xylose, ribose, glucose, galactose, mannose, fructose, cane sugar, lactose, maltose and raffinose, the suspension additionally contains about 0.01 to 2% by weight of at least one of polyvinyl alcohol and lignin sulphonate, and the mixture is heated in the autoclave to a temperature of from about 250° to 500° C.
References Cited (Backward Citations)
US3557266A
Cited
US3989794A
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 |