US3841907A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ferromagnetic chromium dioxide crystals and magnetic recording medium containing same
Assignee: BASF SE
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Filing: 1972-04-18
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Granted: 1974-10-15
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Expires: 1992-04-18
Abstract
Abstract The invention relates to ferromagnetic chromium dioxide crystals which are particularly suitable as magnetic pigments for magnetic recording media and which are stabilized by sparingly watersoluble metal compounds whose cations form sparingly watersoluble metal chromates (such as lead hydroxide, barium phosphate, lead silicate and calcium sulfate) applied to, and particularly precipitated onto, the surface thereof, and to a process for their production.
Inventors
- 👤 M Ohlinger
- 👤 B Leutner
- 👤 M Schwarzmann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 14:38
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70636; C; C01; C01G; C01G37/00; C01G37/02
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
41 words
STABILIZED FERROMAGNETIC CHROMIUM DIOXIDE WHICH COMPRISES CHROMIUM DIOXIDE CRYSTALS IN WHICH THE SURFACE OF SAID CRYSTALS IS COATED WITH FROM 0.1 TO 30 PERCENT BY WEIGHT OF THE CHROMIUM DIOXIDE OF A SUBSTANTIALLY WATER-INSOLUBLE COMPOUND SELECTED FROM THE GROUP CONSISTING OF
Claim 2
Dependent Claim
41 words
STABILIZED FERROMAGNETIC CHROMIUM DIOXIDE WHICH COMPRISES CHROMIUM DIOXIDE CRYSTALS IN WHICH THE SURFACE OF SAID CRYSTALS IS COATED WITH FROM 0.1 TO 30 PERCENT BY WEIGHT OF THE CHROMIUM DIOXIDE OF A SUBSTANTIALLY WATER-INSOLUBLE COMPOUND SELECTED FROM THE GROUP CONSISTING OF
Claim 3
Dependent Claim
9 words
THE OXIDES, HYDROXIDES, SULFIDES AND SILICATES OF DIVALENT LEAD;
Claim 4
Dependent Claim
9 words
THE OXIDES, HYDROXIDES, SULFIDES AND SILICATES OF DIVALENT LEAD;
Claim 5
Dependent Claim
9 words
THE SULFATES AND SILICATES OF CALCIUM, STRONTIUM AND BARIUM;
Claim 6
Dependent Claim
9 words
THE SULFATES AND SILICATES OF CALCIUM, STRONTIUM AND BARIUM;
Claim 7
Dependent Claim
37 words
A magnetic recording medium containing as the magnetic pigment ferromagnetic chromium dioxide crystals coated with from 0.1 to 30 percent by weight of the chromium dioxide of a substantially water-insoluble compound selected from the group consisting of
Claim 8
Dependent Claim
37 words
A magnetic recording medium containing as the magnetic pigment ferromagnetic chromium dioxide crystals coated with from 0.1 to 30 percent by weight of the chromium dioxide of a substantially water-insoluble compound selected from the group consisting of
Claim 9
Dependent Claim
9 words
the sulfates and silicates of calcium, strontium and barium;
Claim 10
Dependent Claim
9 words
the sulfates and silicates of calcium, strontium and barium;
Claim 11
Dependent Claim
9 words
the sulfates and silicates of calcium, strontium and barium;
Claim 12
Dependent Claim
9 words
the sulfates and silicates of calcium, strontium and barium;
Claim 13
Dependent Claim
28 words
the salt of an alkane carboxylic acid having six to 24 carbon atoms and a metal cation selected from the group consisting of divalent lead and mercury; and
Claim 14
Dependent Claim
28 words
the salt of an alkane carboxylic acid having six to 24 carbon atoms and a metal cation selected from the group consisting of divalent lead and mercury; and
Claim 15
Dependent Claim
28 words
the salt of an alkane carboxylic acid having six to 24 carbon atoms and a metal cation selected from the group consisting of divalent lead and mercury; and,
Claim 16
Dependent Claim
28 words
the salt of an alkane carboxylic acid having six to 24 carbon atoms and a metal cation selected from the group consisting of divalent lead and mercury; and,
Claim 17
Dependent Claim
28 words
THE SALT OF AN ALKANE CARBOXYLIC ACID HAVING SIX TO 24 CARBON ATOMS AND A METAL CATION SELECTED FROM THE GROUP CONSISTING OF DIVALENT LEAD AND MERCURY; AND
Claim 18
Dependent Claim
28 words
THE SALT OF AN ALKANE CARBOXYLIC ACID HAVING SIX TO 24 CARBON ATOMS AND A METAL CATION SELECTED FROM THE GROUP CONSISTING OF DIVALENT LEAD AND MERCURY; AND
Claim 19
Dependent Claim
5 words
THE CHROMATES OF DIVALENT LEAD.
Claim 20
Dependent Claim
5 words
THE CHROMATES OF DIVALENT LEAD.
Claim 21
Dependent Claim
5 words
the chromates of divalent lead.
Claim 22
Dependent Claim
5 words
the chromates of divalent lead.
Claim 23
Dependent Claim
5 words
the chromates of divalent lead.
Claim 24
Dependent Claim
5 words
the chromates of divalent lead.
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) | 1977-10-14 | 1978-04-15 | 1978-10-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-14 | 1982-04-15 | 1982-10-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-14 | 1986-04-15 | 1986-10-15 | $7700.00 | Window Closed / Lapsed |