JPS6238534A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve wear resistance by incorporating TiC powder into a magnetic layer. CONSTITUTION:The TiC powder is incorporated into the magnetic layer. The TiC powder to be used is an extremely hard polishing agent having the cubic crystal structure and 9 Mohs' hardness. Said powder has an excellent function to reinforce the magnetic layer and has good affinity to a binder resin. The TiC powder to be used has the average particle size within a 0.1-2.0mum range and is used preferably by incorporating the same into the magnetic layer within a 0.1-10wt% range by the weight of the magnetic powder. The magnetic recording medium is formed by mixing and dispersing the TiC powder together with the magnetic powder, binder resin, org. solvent, etc. to prepare a magnetic coating compd., coating the compd. on a substrate by an optional coating means and drying the coating. The wear resistance is thereby improved and the magnetic recording medium having excellent durability and electromagnetic conversion characteristic is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording medium, and more particularly to a magnetic recording medium that is excellent in durability and electromagnetic conversion characteristics.

[Conventional technology]

In general, magnetic recording media, which are made by coating a magnetic paint consisting of magnetic powder, a binder component, an organic solvent, and other necessary components on a substrate such as a polyester film, come into violent sliding contact with magnetic heads, etc. during recording and playback. The magnetic layer is easily abraded, and a magnetic layer with low abrasion and excellent durability is required.

Therefore, as a measure to improve the wear resistance of the magnetic layer, various abrasives are mixed into the magnetic layer.
For example, α-Fe203 powder, Al2O3 powder% cr
Incorporation of abrasives such as 2o3 powder and T i O2 powder have been proposed. (Special Public Interest Publication No. 47-18572
(No. 52-28642) [Problems to be solved by the invention] However, when these abrasives are mixed into the magnetic layer,
The abrasive action of reinforcing the magnetic layer improves the abrasion resistance of the magnetic layer surface, but it is not sufficient, especially in complex running mechanisms that include low-speed and high-speed running, such as in recent VTRs. Abrasion resistance cannot be obtained.

[Means for solving problems]

This invention was made as a result of extensive research in view of the current situation, and by incorporating TiC powder into the magnetic layer, the reinforcing function of the magnetic layer is further improved, and even when running at low speed or high speed, etc. The abrasion resistance of the magnetic layer is sufficiently improved and the durability is sufficiently improved even in the case of a complicated traveling mechanism including the following.

The TiC powder used in this invention is a very hard lSIF with a cubic crystal structure and a Mohs hardness of 9.
It is an Ig agent that has an excellent magnetic layer reinforcing function and is compatible with binder resin. Therefore, if this type of TiC powder is contained in the magnetic layer, the wear resistance of the magnetic layer will be sufficiently improved and the durability will be sufficiently improved even in a complicated running mechanism that includes low-speed and high-speed running. At the same time, the electromagnetic conversion characteristics are also improved.

Such TiC powder has an average particle size of 0.1 to 2.0.
It is preferable to use one within the μm range, and 0.1 μm.
If the diameter is smaller than m, a large amount is required to obtain sufficient wear resistance, and if the diameter is larger than 2.0 μm, the surface smoothness of the magnetic layer may be impaired and the electromagnetic conversion characteristics may be adversely affected. If the amount used is less than 0.1% by weight based on the magnetic powder, the wear resistance will not be sufficiently improved;
If Li exceeds 1%, the amount of magnetic powder will decrease relatively, and the surface smoothness of the magnetic layer may be impaired, leading to a decrease in electromagnetic conversion characteristics. Preferably, it is contained in the layer.

Moreover, this kind of TiC powder is α-Fe203 powder, A
It may be used in combination with conventionally used polishing agents such as l2O3 powder, Cr2O3 powder, and TiO2 powder.

Examples of magnetic powder include γ-Fe203 powder, F
e3O4 powder, CO-containing r-Fe20° powder, Co-containing Fe50. In addition to powder and CrO2 powder, various conventionally known magnetic powders such as Fe powder, Co powder, Fe-Ni powder, and barium ferrite powder are widely used.

In addition, binder components include vinyl chloride-vinyl acetate copolymers, cellulose resins, polyurethane resins, polyester resins, acrylic resins, rubber resins, and isocyanate compounds, which are usually used as binder components for magnetic powders. Widely used.

The magnetic recording medium of the present invention may be manufactured according to a conventional method. For example, TiC powder is mixed and dispersed with magnetic powder, binder resin, organic solvent, etc. to prepare a magnetic paint, and this is applied to polyester It may be applied onto a substrate such as a film using any coating means such as a roll coater, and then dried.

In addition, various additives commonly used in magnetic paints,
For example, lubricants and dispersants such as fatty acids, fatty acid esters, silicone lubricants, and fluorine-based lubricants, and antistatic agents such as carbon black may be optionally added.

〔Example〕

Next, embodiments of the invention will be described.

Examples 1 to 5 CO-containing r-Fe203 powder ioo wit part (average particle size 0.4 μm) Nitrified cotton (16% cyclohexanone 56.3 -toluene solution) Carbon black 4 (average particle size 24 mμm) Stearic acid Zinc 0.5〃Cyclohexanone 90〃Toluene
90 To this composition, TiC powder and various polishing agents were added in the proportions shown in Table 1 below, mixed for 3 hours using a high-speed 1a stirrer, and then mixed and dispersed using a sand mill. Thereafter, the following composition was prepared: polyurethane resin (20% cyclo, 40 parts by weight hexanone-toluene solution) trifunctional low molecular weight isocyanate-4 compound (75% ethyl acetate solution) n-butyl stearate 1 myristic acid 2 cyclohexanone
35〃Toluene 3
5) were added in an appropriate order, mixed and dispersed for 1 hour using a high-speed stirrer, and passed through a filter to cleave the magnetic paint.

This magnetic paint was applied onto a polyester film having a thickness of about 13 μm to a dry thickness of about 5 μm, dried, and calendered to form a magnetic layer. After that, they were cut to the specified width and made into video tapes.

Comparative Examples 1 to 4 In the composition of the magnetic paint in Example 1, TiC powder was omitted and Cr2O3 powder, Al2O3 powder and α-F
A videotape was made in the same manner as in Example 1 except that e203 powder was used in the proportions shown in Table 1 below.

The video tapes obtained in each Example and Comparative Example were examined for surface roughness of the magnetic layer, color S/N ratio, head wear, still characteristics, and slow motion playback using the following methods.

Surface Roughness of Magnetic Layer> The centerline roughness (Ra) of the videotape was measured using a stylus type surface roughness meter.

Color S/N ratio: A single-color chroma signal is recorded and played back on a videotape using a VTR of the S system, and the AM noise component of the playback signal is measured using a color video noise measuring device.
The N ratio was calculated and expressed as a relative value to the reference tape.

<Head wear> A videotape was run 100 times using a V1-IS system VTR in an environment of 40° C. and 80% R)I, and then the head wear amount of the video head was measured.

<Still characteristics> A videotape was played in still mode for 2 hours using a VTR of the V II S system, and then the degree of scratches on the part that was in contact with the video head was observed, and those with no scratches were marked (○ ), those slightly observed were evaluated as (Δ), and those observed significantly were evaluated as (x).

Slow-motion playback> Using a VH3 VTR, run the videotape 10 times at 1/10 of the normal playback tape feed speed, then observe the extent of scratches on the magnetic layer and check to see if there are any scratches. things (○), things that are slightly recognized (△),
Those that were significantly observed were evaluated as (x).

Table 2 below shows the results.

As is clear from Table 2 above, the videotapes obtained in Examples 1 to 5 all had less head wear and improved still characteristics and slow motion compared to the videotapes obtained in Comparative Examples 1 to 4. The reproduction is good, and the surface smoothness and color S/N ratio are also good, which shows that the magnetic recording medium obtained by the present invention has good abrasion resistance, and is excellent in durability and electromagnetic conversion characteristics.

Patent applicant Kuchidate Maxell Co., Ltd. Tan?゛−′phrase

Claims (1)

[Claims] 1. A magnetic recording medium characterized by containing TiC powder in the magnetic layer