JPS62185236A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain the titled recording medium having an excellent electromagnetic conversion characteristic, running property and durability by forming a magnetic layer in such a manner that at least either of an inorg. silicon compd. or org. silicon compd. is not incorporated therein. CONSTITUTION:The magnetic layer of the magnetic recording medium provided with the magnetic layer on a nonmagnetic substrate is so formed that at least either of the inorg. silicon compd. or org. silicon compd. is not incorporated therein. The surface of the glass part exposed on the contact surface with a magnetic head in sliding contact therewith maintains always the same clean surface as in the initial period if the magnetic recording medium having the magnetic layer which does not contain the inorg. or org. silicon compd. is manufactured and is run in a magnetic recording apparatus. The effect that the deterioration in electromagnetic conversion characteristic and the formation of head running flaws on the magnetic surface are hardly generated is thereby obtd. and the recording medium having the excellent running durability is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to magnetic recording media such as magnetic tapes, magnetic sheets, and magnetic disks used in audio equipment, video equipment, computers, and the like.

BACKGROUND OF THE INVENTION In recent years, there has been a demand for higher and higher recording densities in these various magnetic recording media. For this reason, efforts are being made to shorten the recording wavelength, narrow the track width, and reduce the thickness of the recording medium to reduce the minimum recording unit.

However, if you simply increase the recording density in this way, 1
Generally, S/N and output 1 frequency characteristics are disadvantageous. Countermeasures include improving the saturation magnetic flux density (Br) and squareness ratio, which are magnetic properties, smoothing the magnetic surface to reduce air gap loss, and increasing the density of magnetic particles and making them finer. There is. Among these, the most effective method is to make the magnetic surface as smooth as possible to obtain high output and reduce modulation noise caused by surface roughness. However, on the other hand, the coefficient of friction of the magnetic surface increases, which is disadvantageous in terms of running durability.

In magnetic recording media, especially video tape.

In order to run stably while contacting tape guides, posts, cylinders, fixed magnetic heads, etc., it also has a low coefficient of friction and is resistant to wear because it is subjected to intense friction from the high-speed rotating video head.

It is required to have excellent durability.

Therefore, for magnetic recording media aiming at high-density recording, high S/N, and high output, it is desirable to have a highly smooth magnetic surface and at the same time have a small coefficient of friction on both the front and back sides of the magnetic recording medium and excellent wear resistance. There is.

These prior art techniques include fatty acid esters and magnetic layers in the magnetic layer.
Methods of incorporating lubricants such as fatty acids, silicone oils, and fluorine oils (Japanese Patent Publication No. 43-23889, Japanese Patent Publication No. 61-39081, Japanese Patent Publication No. 49-14249) and providing a back coat layer (Japanese Patent Publication No. 49-1989) It is known that the coefficient of friction of a magnetic recording medium can be lowered and the running performance and durability can be improved by methods such as Japanese Patent Publication No. 8321 and Japanese Patent Publication No. 51-29642.

Problems to be Solved by the Invention However, even with the above method, it has not been possible to obtain a magnetic recording medium that has sufficiently satisfactory electromagnetic conversion characteristics and durability.

As a result of intensive research into the above-mentioned problems, we found that if at least a small amount of inorganic silicon compounds or organic silicon compounds is present in the magnetic layer or magnetic surface, it may occur due to high-speed sliding contact between the magnetic surface and the magnetic head during running. Under the frictional heat and contact pressure, the inorganic silicon compound or organic silicon compound present on the magnetic surface and the glass part partially exposed on the sliding surface of the magnetic head react mechanochemically, and this glass It was found that countless minute protrusions were generated on the surface, making the surface rough.

Therefore, the above-mentioned minute protrusions grow with running time, which increases the air gap loss between the magnetic surface and the magnetic head, resulting in a decrease in the output or S/N, and at the same time, these minute protrusions cause scratches on the magnetic surface. It is presumed that the durability is deteriorated due to an increase in dust removal, dropouts, etc.

In view of the above problems, the present invention provides a magnetic recording medium with excellent electromagnetic conversion characteristics, running properties, and durability.

Means for Solving the Problems In order to solve the above problems, the present invention provides a magnetic recording medium in which a magnetic layer is provided on a non-magnetic support, in which at least an inorganic silicon compound or an organic silicon compound is added to the magnetic layer. This magnetic recording medium is characterized in that it does not include the other.

Effect of the present invention With the above structure, a magnetic recording medium having a magnetic layer not containing an inorganic or organic silicon compound is manufactured, and when it is run in a magnetic recording device, the magnetic layer is exposed on the contact surface of a magnetic head in sliding contact with the magnetic recording medium. The surface of the glass portion always maintains the same clean surface as the initial state, and the effect is that deterioration of electromagnetic conversion characteristics and head running scratches on the magnetic surface are less likely to occur.

Example Examples of the present invention will be specifically described below.

It should be noted that all parts in the component ratios described in the examples are parts by weight.

Example The magnetic paint was prepared as follows.

GO-containing magnetic iron oxide powder 100 parts Average particle size Length = 0.3 μm Acicularity ratio = 10/1 Coercive force = 66006 Polyurethane resin 10 parts Vinyl chloride-vinyl acetate copolymer 10 parts Alumina oxide (α
-Ae203) 2 parts Average particle size = 0.2 μm Carbon black 1 part Lecithin 1 part Myristic acid
2-part methyl ethyl ketone (M
RK) 100 parts toluene
100 parts cyclohexanone
After mixing and dispersing 60 parts of the above composition in a ball mill for 24 hours, 5 parts of a hardening agent (Coronate L) was added and the resulting mixture was filtered through a filter having an average pore size of 1 μm to prepare a magnetic coating solution. Next, this coating solution was applied onto a 15 μm thick polyester film (PIET), oriented in a magnetic field, dried, and the magnetic layer was surface treated using a super calender (surface treatment machine) and shredded into A inch width pieces. A videotape with a magnetic layer thickness of 6 μm was produced.

Comparative Example 1 Average particle size in the magnetic paint of the above example. A videotape was produced in the same manner as in Example except that 1.0 part of 5i02 powder of 2 μm was further added.

Comparative Example 2 A videotape was produced in the same manner as in the example except that 0.5 part of a silane coupling agent (TSL8331 manufactured by Toshiba Silicon) was added to the magnetic paint of the above example.

The characteristics of each sample above are shown in the table below.

(Left below) The characteristic values in the table above were determined using the following method.

(1) Roughness of magnetic surface Rank Taylor-Hobson
Hobson) Talystep surface roughness meter (
The surface roughness of the sample was measured using an LPF: 2 esHz), and the root mean square roughness of the height was calculated on the obtained roughness chart.

(2) Friction coefficient Output tension when the back side of the tape is in contact with an aluminum alloy drum with a diameter of 126fl over half its circumference, and the input tension on the drum is set to 36I and the tape running speed is set to 3.2α/sec. was measured, and the coefficient of friction was determined from the following equation.

(3) Amount of output variation Using a VH3 type VTR (NY-8200 manufactured by Matsushita Electric Industrial Co., Ltd.), a single aMHz signal was recorded for 3 minutes, and the reproduction output of that portion was first measured. Next, let it play for 30 minutes, rewind it, and measure the playback output of the first 3 minutes of recording.
The difference from the above reproduction output is defined as an output change.

(4) Changes in the number of dropouts Record a video signal for 10 minutes using the same VTR used in (3) above, and calculate the dropouts (16μ515
0.16 dB instantaneous loss of playback output) is measured with a dropout counter.

Next, after repeatedly running the recorded portion 100 times, the number of dropouts is similarly measured, and the difference from the above-mentioned initial value is taken as the amount of change in the number of dropouts.

The dropout value is the average value per minute of the recorded portion.

(5) Rough condition of head sliding surface glass portion The video head sliding surface of the same VTR used in (3) above was observed using an optical microscope.

Effects of the Invention From the results of the Examples and Comparative Examples described above, it has been found that the magnetic recording medium according to the present invention, which does not contain at least one of an inorganic silicon compound and an organic silicon compound in its magnetic layer, has a magnetic recording medium that does not contain at least one of an inorganic silicon compound and an organic silicon compound. It has excellent electromagnetic conversion characteristics and running durability without impairing the surface properties of the glass part, and has great practical value.

Claims (1)

[Claims] A magnetic recording medium comprising a magnetic layer provided on a non-magnetic support, characterized in that the magnetic layer does not contain at least one of an inorganic silicon compound and an organic silicon compound.