Claims
- 1. Acicular iron metal pigments for magnetic signal recording, having a high saturation magnetization M.sub.S (>160 mT cm.sup.3 /g) and remanence M.sub.R (>80 mT cm.sup.3 /g), the coercive field strength H.sub.C of which at a given initial crystallite size is adjustable to between 35 kA/m and 125 kA/m by means of a thermal after-treatment.
- 2. Acicular iron metal pigments according to claim 1, characterized in that the saturation magnetization is within the range of from 160 to 225 mT.cm.sup.3 /g and the remanence M.sub.R is from 80 to 115 mT.cm.sup.3 /g.
- 3. Acicular non-sintered iron metal pigments for magnetic signal recording, having a high saturation magnetization M.sub.S (>160 mT cm.sup.3 /g) and the remanence M.sub.R (>80 mT cm.sup.3 /g), the coercive field strength H.sub.C of which at an initial crystallite size in the range of 16 nm is H.sub.C from 35 to 90 kA/m.
- 4. The compound NR".sub.4 (BR.sub.n (OR').sub.3-n H) produced from ammonium salts NR".sub.4 Y and MH.sub.x.(BR.sub.3).sub.x, wherein R=C.sub.1 -C.sub.6 alkyl, Ar-C.sub.1 -C.sub.6 alkyl; R'=C.sub.1 -C.sub.6 alkyl, aryl (phenyl), Ar-C.sub.1 -C.sub.6 alkyl; R"=C.sub.1 -C.sub.6 alkyl, aryl, Ar-C.sub.1 -C.sub.6 alkyl, tri-C.sub.1 -C.sub.6 alkylsilyl; Y is an anion, and M is a metal of the first or second groups of the Periodic Table of Elements.
- 5. The compound CaH.sub.2.(BR.sub.3).sub.2 in which R is C.sub.1 -C.sub.6 alkyl, produced in situ from Ca, H.sub.2 and trialkyl borane.
- 6. A magnetic recording medium, containing at least one iron metal pigment according to claim 1.
Priority Claims (1)
Number |
Date |
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3901027 |
Jan 1989 |
DEX |
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Parent Case Info
This is a continuation of application Ser. No. 705,470, filed May 24, 1991, which is a division of Ser. No. 463,764, filed Jan. 12, 1990 now U.S. Pat. No. 5,053,075.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
4447264 |
Suzuki |
May 1984 |
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Non-Patent Literature Citations (1)
Entry |
Fumio Watari, "Effect of Crystalline Properties on Coercive Force in Iron Acicular Fine Particles," Apr., 1988, pp. 1260-1264, in Journal of Materials Science 23. |
Divisions (1)
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Number |
Date |
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Parent |
463764 |
Jan 1990 |
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Continuations (1)
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Number |
Date |
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Parent |
705470 |
May 1991 |
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