Patent US3969494A successfully refreshed from Google Patents.
US3969494A
Expired / Lapsed
US
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Method for improvement of properties of synthetic yellow iron oxide
Assignee: National Institute of Advanced Industrial Science and Technology
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Filing: 1975-02-21
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Granted: 1976-07-13
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Expires: 1995-02-21
Abstract
Abstract Synthetic yellow iron oxide ( alpha -FeOOH) is dispersed in an aqueous 0 - 10N alkali solution and the resultant dispersion is subjected to a hydrothermal treatment at 100 DEG - 250 DEG C. This treatment improves the synthetic yellow iron oxide in that it converts imperfect crystals present in said iron oxide into perfect crystals, changes particles thereof from the shape of needles to that of rods, makes the particle size substantially uniform and heightens the resistivity thereof to heat by about 50 DEG C. The modified synthetic yellow iron oxide thus obtained is innoxious and can be used as a pigment in paints.
Inventors
- 👤 Soichiro Nobuoka
- 👤 Takashi Asai
- 👤 Kazuaki Ado
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 16:56
CPC Classifications
C; C09; C09C; C09C1/00; C09C1/22; C09C1/24; C01; C01G; C01G49/00; C01G49/02; C01G49/06; C01P; C01P2002/00; C01P2002/70; C01P2002/72; C01P2004/00; C01P2004/01; C01P2004/03; C01P2004/10; C01P2004/12; C01P2004/54; C01P2004/60; C01P2004/62; C01P2006/00; C01P2006/12; C01P2006/32; C01P2006/37; C01P2006/42; C01P2006/60
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
61 words
A method for the improvement of properties of synthetic yellow iron oxide, which comprises dispersing said synthetic yellow iron oxide in an aqueous 0 - 10N alkali solution, subjecting the resultant slurry to a hydrothermal treatment at temperatures in the range of 100° - 250°C under saturated pressure of steam and recovering from the hydrothermally treated slurry the yellow iron oxide.
Claim 2
Independent Claim
61 words
A method for the improvement of properties of synthetic yellow iron oxide, which comprises dispersing said synthetic yellow iron oxide in an aqueous 0 - 10N alkali solution, subjecting the resultant slurry to a hydrothermal treatment at temperatures in the range of 100° - 250°C under saturated pressure of steam and recovering from the hydrothermally treated slurry the yellow iron oxide.
Claim 3
Independent Claim
55 words
A method for the improvement of properties of synthetic yellow iron oxide, which comprises dispersing said synthetic yellow iron oxide in water, subjecting the resultant slurry to a hydrothermal treatment at temperatures in the range of 100° - 250°C under saturated pressure of steam and recovering from the hydrothermally treated slurry the yellow iron oxide.
Claim 4
Independent Claim
55 words
A method for the improvement of properties of synthetic yellow iron oxide, which comprises dispersing said synthetic yellow iron oxide in water, subjecting the resultant slurry to a hydrothermal treatment at temperatures in the range of 100° - 250°C under saturated pressure of steam and recovering from the hydrothermally treated slurry the yellow iron oxide.
Claim 5
Dependent Claim
33 words
The method according to claim 1 wherein the mother liquor remaining after the recovery of the yellow iron oxide is put to cyclic use as an aqueous alkali solution in said hydrothermal treatment.
Claim 6
Independent Claim
79 words
A method for the manufacture of a pigment of yellow iron oxide, which comprises dispersing yellow iron oxide in an aqueous 0.5 - 1N sodium hydroxide solution at a ratio of 40 - 100g of said yellow iron oxide to 200ml of said aqueous alkali solution, subjecting the resultant slurry to a hydrothermal treatment at temperatures in the range of 120° - 180°C for about 30 minutes and recovering from the hydrothermally treated slurry the precipitated yellow iron oxide.
Claim 7
Independent Claim
79 words
A method for the manufacture of a pigment of yellow iron oxide, which comprises dispersing yellow iron oxide in an aqueous 0.5 - 1N sodium hydroxide solution at a ratio of 40 - 100g of said yellow iron oxide to 200ml of said aqueous alkali solution, subjecting the resultant slurry to a hydrothermal treatment at temperatures in the range of 120° - 180°C for about 30 minutes and recovering from the hydrothermally treated slurry the precipitated yellow iron oxide.
Claim 8
Independent Claim
125 words
A method for the manufacture of γ-iron oxide of the grade suitable for use in magnetic tapes, which comprises dispersing synthetic yellow iron oxide in an aqueous 0.5 - 1N sodium hydroxide solution at a ratio of 40 - 100g of said synthetic yellow iron oxide to 200ml of said aqueous alkali solution, subjecting the resultant slurry to a hydrothermal treatment at about 150°C for about 30 minutes, recovering from the hydrothermally treated slurry the yellow iron oxide, treating the recovered yellow iron oxide in a current of hydrogen gas at about 360°C for about 2 hours to obtain Fe 3 O 4 and treating the resultant Fe 3 O 4 in the air at about 200°C for about 30 minutes to obtain γ-iron oxide.
Claim 9
Independent Claim
125 words
A method for the manufacture of γ-iron oxide of the grade suitable for use in magnetic tapes, which comprises dispersing synthetic yellow iron oxide in an aqueous 0.5 - 1N sodium hydroxide solution at a ratio of 40 - 100g of said synthetic yellow iron oxide to 200ml of said aqueous alkali solution, subjecting the resultant slurry to a hydrothermal treatment at about 150°C for about 30 minutes, recovering from the hydrothermally treated slurry the yellow iron oxide, treating the recovered yellow iron oxide in a current of hydrogen gas at about 360°C for about 2 hours to obtain Fe 3 O 4 and treating the resultant Fe 3 O 4 in the air at about 200°C for about 30 minutes to obtain γ-iron oxide.
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) | 1979-07-13 | 1980-01-12 | 1980-07-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-07-13 | 1984-01-12 | 1984-07-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-07-13 | 1988-01-12 | 1988-07-13 | $7700.00 | Window Closed / Lapsed |