US2001026880A1PendingUtilityA1

Magnetic recording media

Priority: Mar 27, 1995Filed: Mar 19, 2001Published: Oct 4, 2001

Est. expiryMar 27, 2015(expired)· nominal 20-yr term from priority

Inventors:August Lehner Helmut Jakusch Volker Koch Manfred Ohlinger Albert Kohl Werner Lenz Norbert Schneider Peter Heilmann Werner Hubner Erich Hoffmann Ronald J. Veitch Rudi Lehnert Harald Jachow

G11B 5/708G11B 5/733Y10S428/90Y10T428/257Y10T428/256

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References

Claims

Abstract

Tape-like magnetic recording media having a nonmagnetic substrate and at least one layer applied to the substrate having incorporated into at least one of these layers, an inorganic needle-shaped pigment which serves as a supporting pigment and has a ratio of the average length to the average diameter of the pigment of at least 3, and the mean modulus of elasticity of the layers is not less than 15 Gpa in the longitudinal direction of the tape-like recording media.

Claims

exact text as granted — not AI-modified

We claim:

1 . A tape-like, magnetic recording medium I comprising a nonmagnetic substrate III, at least one layer applied to this substrate and, in at least one of these layers, an inorganic needle-shaped pigment II which is suitable as a supporting pigment and has a ratio of the average length to the average diameter of the pigment II of from 3:1 to 15:1, wherein the mean modulus of elasticity of the stated layers is not less than 15 GPa in the longitudinal direction of the tape-like recording medium I.

2 . A tape-like, magnetic recording medium I as claimed in claim 1 , having a modulus of elasticity in the longitudinal direction of the tape-like recording medium I of not less than 20 GPa.

3 . A recording medium I as claimed in claim 1 or 2 , comprising
a) a nonmagnetic substrate III and
b) a layer IV suitable for magnetic information storage.

4 . A recording medium I as claimed in any of claims 1 to 3 , comprising a layer V which contains a binder and the supporting pigment II.

5 . A recording medium I as claimed in any of claims 1 to 4 , wherein the nonmagnetic substrate III contains the supporting pigment II.

6 . A recording medium I as claimed in any of claims 1 to 5 , wherein the layer IV suitable for magnetic information storage contains the supporting pigment II.

7 . A recording medium I as claimed in claim 3 , wherein a layer V is arranged between the nonmagnetic substrate III and the layer IV suitable for magnetic information storage.

8 . A recording medium I as claimed in claim 3 , wherein the nonmagnetic substrate III is arranged between a layer V and the layer IV suitable for magnetic information storage.

9 . A recording medium I as claimed in any of claims 1 to 8 , wherein the layer IV suitable for magnetic information storage contains a binder and finely divided ferromagnetic pigments.

10 . A recording medium I as claimed in any of claims 1 to 8 , wherein the layer IV suitable for magnetic information storage essentially comprises a ferromagnetic metal or ferromagnetic alloy.

11 . A recording medium I as claimed in any of claims 1 to 10 , containing a ferromagnetic pigment as supporting pigment II.

12 . A recording medium I as claimed in claim 11 , containing ferromagnetic metal or alloy pigments as supporting pigment II.

13 . A recording medium I as claimed in claim 11 , containing ferromagnetic metal oxide pigments as supporting pigment II.

14 . A recording medium I as claimed in claim 13 , containing γ-Fe 2 O 3 pigments, Co-containing γ-Fe 2 O 3 pigments, γ-Fe 3 O 4 pigments or CrO 2 pigments as supporting pigment II.

15 . A recording medium I as claimed in claim 13 , containing, as supporting pigment II, needle-shaped chromium-containing pigments of the formula VI
Cr a O x .n H 2 O VI
where
a is the average valency of the chromium with 3.0&lt;a≦3.25,
x is the oxygen equivalents determined by the valency of the chromium and
n is the water content with 0&lt;n&lt;(4−a)/2,
having a ratio of the average length of the needles to the average diameter of the needles of from 3:1 to 10:1.

16 . A recording medium I as claimed in claim 15 , wherein the pigments VI consist of
a) 50% by weight of a core and b) 50% by weight of a shell and the atomic ratios of Cr(IV) to Cr(III) in the core and in the shell are identical.

17 . A recording medium I as claimed in claim 15 , wherein the pigments VI consist of
a) 50% by weight of a core and b) 50% by weight of a shell and the atomic ratio of Cr(IV) to Cr(III) in the shell is greater than that in the core.

18 . A recording medium I as claimed in claim 15 , wherein the pigments VI consist of
a) 50% by weight of a core and b) 50% by weight of a shell and the atomic ratio of Cr(IV) to Cr(III) in the core is greater than that in the shell.

19 . A recording medium I as claimed in any of claims 1 to 10 , containing a nonferromagnetic pigment as supporting pigment II.

20 . A recording medium I as claimed in claim 19 , containing FeOOH or α-Fe 2 O 3 as supporting pigment II.

21 . A recording medium I as claimed in claim 19 , containing, as supporting pigment II, a pigment of the formula VII
Cr 2 O 3 .n H 2 O VII
where
n is from 0 to 0.5,
having a ratio of the average length of the needles to the average diameter of the needles of from 3:1 to 10:1.

22 . A recording medium I as claimed in any of claims 14 to 18 and 21 , containing
a) a nonmagnetic substrate III and, arranged thereon,
b) a layer V which contains a binder and a chromium-containing needle-shaped metal oxide having a ratio of the average length to the average diameter of the pigment of at least 7 and an orientation ratio of at least 4 and, arranged thereon,
c) a layer IV suitable for information storage and containing a binder and ferromagnetic metallic pigments,
the modulus of elasticity in the longitudinal direction of the tape-like recording medium I being greater than 30 GPa.

23 . A pigment VI or VII suitable as a supporting pigment and according to the definition in claims 15 to 18 , 21 and 22 .

24 . A supporting pigment as claimed in claim 23 , having an average needle length of from 100 to 400 nm.

25 . A process for the preparation of the pigments VI and VII as claimed in claims 23 and 24 , wherein pigments of the formula VIII
CrO x VIII
where
x is 1.8≦x≦2.2,
a) are heated at from 400 to 500° C. or
b) are reacted under hydrothermal conditions at from 110 to 250° C. with a reducing agent and then heated at from 200 to 400° C.

26 . The use of pigments VI and VII as claimed in claims 23 and 24 for modifying the mechanical properties of the polymeric materials.

27 . The use as claimed in claim 26 for an isotropic modification of the mechanical properties of polymeric materials.

28 . A method for modifying the mechanical properties of polymeric materials, wherein pigments VI or VII are incorporated into melts or solutions of polymeric materials or melts or solutions of compounds from which polymeric materials can be prepared, and the mixture is then cured or allowed to solidify.

29 . A method as claimed in claim 28 , anisotropic modification of the mechanical properties of polymeric materials being effected, wherein the pigments are rheologically oriented and the materials are cured or allowed to solidify.

30 . A method as claimed in claim 29 , wherein the pigments VI are oriented in an external magnetic field and the materials are cured or allowed to solidify.

31 . A polymeric material obtainable as claimed in any of claims 28 to 30 .

32 . A magnetic recording medium produced with the use of a polymeric material as claimed in claim 31 .

33 . A recording medium I as claimed in any of claims 15 to 18 , containing pigments VI, oriented in an external magnetic field.

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