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Magnetic tape and magnetic tape cartridge

a magnetic tape and cartridge technology, applied in the field of coating type magnetic tape, can solve the problems of inability to overcome the problem, the production output decreases, and the formation of a thin layer of magnetic tape, and achieve the effect of high recording density

Inactive Publication Date: 2006-01-05
KUSE SADAMU +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0029] (1) Magnetic powder having a coercive force as high as possible, to an extent that the deletion of records with a magnetic head is possible.
[0041] Further, by containing the non-magnetic plate particles, variation in the thickness of (the magnetic layer+the primer layer) and variation in the thickness of the backcoat layer are lessened to thereby reduce the deformation of a magnetic sheet wound up (the formation of raised stripes, and dislocation of the edges of a wound tape), and thus, it is found that edge weaves caused on the edges of tape when the magnetic sheet is slit into tapes is reduced.

Problems solved by technology

Therefore, in case where the thickness of a magnetic layer is large, the saturation magnetization and the coercive force of conventional magnetic powder are insufficient within the shortest recording wavelength region, so that the reproducing output decreases to a fraction thereof.
Further, because the recording wavelength is very short, self demagnetization loss and thickness loss due to the thickness of a magnetic layer give adverse influences on the resolution, although such demagnetization loss and thickness loss which occur when recorded signals are reproduced have not arisen so serious problem so far.
This problem can not be overcome by the above improvement of the magnetic characteristics of magnetic powder and the improvement of the surfaces of magnetic layers by the medium-producing technique.
However, there arise other problems in the formation of a thinner magnetic layer.
That is, when the thickness of a magnetic layer is reduced, the surface roughness of a non-magnetic support gives an adverse influence on the surface of the magnetic layer, so that the surface smoothness of the magnetic layer degrades.
However, the defects of coating are not eliminated and the filling of magnetic powder is not improved by these methods, which results in poor film strength.
The two-reel type cartridge has other problems in that the dimensions of the cartridge become larger and that the memory capacity per volume becomes smaller.

Method used

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Examples

Experimental program
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Effect test

example 1

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[0136] Iron nitrate (III) (0.074 mol) and neodymium nitrate (0.002 mol) were dissolved in water (600 cc). Separately from this aqueous solution of nitrates, sodium hydroxide (0.222 mol) was dissolved in water (600 cc). To this aqueous sodium hydroxide solution, was added the aqueous nitrate solution, and the mixture was stirred for 5 minutes to form a hydroxide (co-precipitate) of iron and neodymium. The hydroxide was washed with water and filtered to collect the hydroxide. To this hydroxide (containing water), were further added water (30 cc) and boric acid (H3BO3) (0.5 mol), and the mixture was heated at 60° C. in an aqueous boric acid solution, while the hydroxide of iron and neydymium was being again dispersed. The resultant dispersion was spread onto a vat and dried at 60° C. for 4 hours to evaporate off water. Thus, a homogenous mixture of the hydroxide of iron and neodymium and boric acid was prepared.

[0137] This mixture was crushed and put into an alumina crucible. The mix...

example 2

[0162] A computer tape was made in the same manner as in Example 1, except that magnetic powder prepared by the following synthesis was used.

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[0163] Iron nitrate (III) (0.098 mol), cobalt nitrate (0.042 mol) and neodymium nitrate (0.002 mol) were dissolved in water (200 cc). Separately from this aqueous nitrate solution, an aqueous sodium hydroxide solution was prepared by dissolving sodium hydroxide (0.42 mol) in water (200 cc). To the aqueous nitrate solution, was added the aqueous sodium hydroxide solution, and the mixture was stirred for 5 minutes to form a hydroxide of iron, cobalt and neodymium. This hydroxide was washed with water and filtered to collect the hydroxide. To the hydroxide (containing water), were further added water (150 cc) and boric acid (0.1 mol) so as to again disperse the hydroxide of iron, cobalt and neodymium in this aqueous boric acid solution. The resulting dispersion was treated by heating at 90° C. for 2 hours, and washed with water to remove the exc...

example 3

[0166] A computer tape was made in the same manner as in Example 1, except for magnetic powder. That is, the magnetic powder of Example 3 was prepared in the same manner as in Example 1, except that the temperature and the time of the heat treatment in an air were changed to 120° C. and 4 hour, from 200° C. and 4 hours in Example 1, and that the particle diameter was changed to 15 nm.

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Abstract

A magnetic tape comprising a non-magnetic support, a magnetic layer containing magnetic powder which is formed on one side of the non-magnetic support, a primer layer containing non-magnetic powder which is formed between the non-magnetic support and the magnetic layer, and a backcoat layer containing non-magnetic powder which is formed on the other side of the non-magnetic support, wherein the magnetic layer contains the magnetic powder which comprises plate, granular or ellipsoidal magnetic particles with a particle diameter of 5 to 50 nm, and has a thickness of 0.09 μm or less, and wherein at least one of the primer layer and the backcoat layer contains non-magnetic plate particles with a particle diameter of 10 to 100 nm.

Description

TECHNICAL FIELD [0001] The present invention relates to a coating type magnetic tape with a high recording density. BACKGROUND ART [0002] Magnetic tapes have found various applications in audio tapes, videotapes, computer tapes, etc. In particular, in the field of magnetic tapes for data-backup (or backup tapes), tapes with memory capacities of several tens to 100 GB per reel are commercialized in association with increased capacities of hard discs for back-up. In future, a backup tape with a capacity of 1 TB or more will be proposed, and it is indispensable for such a backup tape to have a higher recording density. [0003] In the production of a magnetic tape capable of meeting such a demand for higher recording density, advanced techniques are required for production of very fine magnetic powder, highly dense dispersion of such magnetic powder in a coating layer, smoothing of such a coating layer, and formation of a thinner magnetic layer. [0004] To increase the recording density, ...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G11B5/708G11B5/706B32B9/00B32B19/00G11B5/70G11B5/714G11B5/735G11B5/738
CPCG11B5/70G11B5/738G11B5/735G11B5/714G11B5/7356G11B5/7368
Inventor KUSE, SADAMUDOI, TSUGIHIROINOUE, TETSUTAROKISHIMOTO, MIKIO
Owner KUSE SADAMU
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