Magnetic recording medium

Inactive Publication Date: 2003-03-25
HITACHT MAXELL LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

It has been determined that the affects on the magnetic and backcoating layer depends not only on the hardness of the particles contained in the layers but also on particle size, and that the reinforcing effect of the particles is decreased when the particle size is smaller than a specific size. In view of this fact, it has been further

Problems solved by technology

However, this patent literature is silent on the relationship between the primary particle size or particle size of agglomerates of the carbon black and the major axis size of the ferromagnetic metal powder in the magnetic layer, or does not investigate the relationship

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example i

A. Formation of a magnetic layer

In a ball mill, a composition of 100 parts of ferromagnetic metal iron powder which comprised aluminum-coated iron particles containing 0.2% by weight of manganese and 1.0% by weight of calcium based on the weight of iron and had coercive force of 1600 Oe, saturation magnetization of 120 emu / g, a major axis size of 0.18 .mu.m and an axial ratio of 10, 10 parts by weight of a hydroxy group-containing vinyl chloride resin having a polymerization degree of 340, 7 parts by weight of a thermoplastic polyurethane resin, 8 parts by weight of alumina having a particle size of 0.2 .mu.m, 2 parts by weight of myristic acid, 2 parts by weight of red oxide (.alpha.-Fe.sub.2 O.sub.3), 1 parts by weight of #4010 having a particle size of 80 m.mu. (manufactured by Mitsubishi Chemical Co., Ltd.) and 2 parts by weight of Seast 5 H having a particle size of 20 m.mu. (manufactured by Tokai Carbon) as carbon black in 70 parts by weight of cyclohexanone and 70 parts by we...

example 2

In the same manner as in Example 1 but using the same amount of Laben Sebacalb MT-Cl having a particle size of 300 m.mu. in place of 7.5 parts by weight of Laben MT-P beads having the particle size of 280 m.mu. (0.28 .mu.m) (manufactured by Columbian Carbon) in the formation of the backcoating layer, a magnetic recording medium was produced.

example 3

In the same manner as in Example 1 but using the same amount of #4010 having a particle size of 80 m.mu. (manufactured by Mitsubishi Chemical) in place of 7.5 parts by weight of Laben MT-P beads having the particle size of 280 m.mu. (0.28 .mu.m) (manufactured by Columbian Carbon) and mixing the composition in the ball mill for 22 hours instead of 96 hours in the formation of the backcoating layer, a magnetic recording medium was produced.

When the magnetic paint was observed after 22 hours mixing in the ball mill, the carbon back particles formed aggromerates each consisting of 13 particles on the average, and the size of aggromerates was 210 m.mu..

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PUM

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Abstract

There is provided a magnetic recording medium which comprises a substrate, a magnetic layer on one surface of a substrate and a backcoating layer on the other surface of the substrate, wherein the magnetic layer contains a magnetic metal powder having a major axis of not larger than 0.2 mum and an inorganic powder having a Mohs' hardness of at least 5, and the backcoating layer contains an inorganic powder having a particle size smaller than the size of the major axis of the magnetic metal powder and which has sufficiently reduced noise at high density recording and high output required in, for example, a small size video tape with high picture quality, the magnetic recording medium in the form of a magnetic tape having a total thickness of not larger than 14 mum inclusive of the substrate, the magnetic layer and the backcoating layer, and reliably maintained not to increase the noise after long term storage.

Description

BACKGROUND OF THE INVENTION1. Field of the InventionThe present invention relates to a magnetic recording medium with reduced noise at high density recording and high Output which are required in, for example, a small size video tape with high picture quality. In particular, the present invention provides a magnetic recording medium, such as a magnetic tape, which has a magnetic layer and a substrate, a backcoating layer having a total thickness of not greater than 14 .mu.m used in a wound form, such that the noise does not increase after long term storage.2. Description of the Related ArtIn general, a magnetic recording medium comprises a substrate made of, for example, a polyester film and a magnetic layer formed on a surface of the substrate by applying a magnetic paint which comprises a magnetic powder, a binder, inorganic powder, a lubricant and the like dispersed in an organic solvent and drying it. In particular, in case of a video tape, a backcoating layer comprising a binde...

Claims

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Application Information

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IPC IPC(8): G11B5/62G11B5/735G11B5/70G11B5/714
CPCG11B5/714G11B5/735Y10T428/257Y10T428/265Y10S428/90Y10T428/26Y10T428/24355Y10T428/25Y10S428/928Y10T428/256G11B5/7358
Inventor KAWARAI, SEIGIYOSHIDA, KENICHIROKATO, AKIRA
Owner HITACHT MAXELL LTD
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