JPS61104424A - Magnetic recording medium and magnetic recording method - Google Patents

Abstract

PURPOSE:To eliminate head sticking and clogging and to obviate the generation of an inconvenience in terms of an electromagnetic conversion characteristic by providing a specific relation among the gap length of a magnetic head, the number and height of projections on a medium surface and the coercive force and forming a thin ferromagnetic metallic film layer so as to have >=0.7 packing rate. CONSTITUTION:The surface of the magnetic recording medium provided with the thin ferromagnetic metallic film layer consisting essentially of Co on a flexible substrate has the projections at average >=10<5>/a<2> pieces for each 1mm<2> of the medium surface where the gap length of the magnetic head is designated as a mum. Moreover, the projections have 30-300Angstrom height. Said medium has the relation (Hc max - Hc min)/Hc(0)<=0.9 when the coercive force of the thin ferromagnetic metallic film layer is measured while the direction is changed on the plane delineated by the longitudinal direction of the base body and the normal of the plane of the base body. The packing rate of the thin ferromagnetic metallic film layer is >=0.7. Here, Hc max denotes the max value of the coercive force, Hc min the min value of the coercive force and Hc(0) the coercive force in the longitudinal direction of the base body.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Background Technical Field of the Invention The present invention relates to a magnetic recording medium, and particularly to a magnetic recording medium having a continuous thin film type magnetic layer formed by a so-called oblique evaporation method, and a magnetic recording method.

Prior art and its problems As magnetic recording media for video, audio, etc., there has been active development of magnetic recording media that have a continuous thin film type magnetic layer on a long substrate due to their compactness when rolled into tapes. It is being done.

Due to its characteristics, the magnetic layer WIJM of such a thin metal Jll type medium is made of Co, Co, etc., which is formed by the so-called oblique evaporation method, in which the evaporation is performed at a predetermined tilt angle with respect to the normal to the substrate.
A deposited film made of -Ni or the like is suitable.

Since the characteristics of such a medium are greatly degraded due to spacing errors, it is necessary to make the surface as smooth as possible.

However, if the surface is made too flat, friction will increase, causing problems in head-to-head contact and running surfaces.

By the way, in a metal thin film type medium, the magnetic layer has a thickness of 0.05 to
Since it is extremely thin at 0.5 μm, the surface properties of the medium depend on the surface properties of the substrate.

For this reason, it has been proposed to provide relatively smooth protrusions on the surface of the substrate, such as wrinkle-like or earthworm-like protrusions (Japanese Unexamined Patent Publication No. 53-11El115, etc.).

Also, JP-A-58-68227, JP-A No. 58-10022
No. 1 proposes disposing fine particles on the surface of the substrate to create irregularities that can be observed at 50 to 400 times magnification with an optical microscope and that can be measured with a stylus surface roughness measuring device. .

However, even these are still insufficient in terms of physical properties such as running friction, running durability, running stability, and electromagnetic conversion characteristics.

On the other hand, in Japanese Patent Publication No. 39-25248, etc., it has been proposed to reduce running friction by providing a top coat layer made of an organic lubricant on the surface of a thin ferromagnetic metal l11M = However, using an organic lubricant Sometimes, lubricant adheres to the head and the head becomes clogged, which poses a serious problem in practice.

On the other hand, a ferromagnetic metal thin film layer formed by oblique evaporation method is 1. It is formed as an aggregate of columnar crystal grains that are inclined with respect to the normal to the main surface of the substrate and whose longitudinal diameter extends over the entire thickness of the ferromagnetic metal thin film layer.

Co, Ni, etc. are present in the columnar crystal grains, and 0, which is introduced as necessary, is present on the surface of the columnar crystal grains.
It exists in the form of an oxide.

However, since such a ferromagnetic metal thin film layer has shape anisotropy in the longitudinal direction of the substrate, that is, in the running direction of the medium, there is a large difference in input/output characteristics depending on whether the running direction of the medium is forward or backward. There is a disadvantage that it occurs.

Therefore, the present inventors first measured the coercive force while changing the direction on a plane defined by the longitudinal direction of the substrate and the normal direction of the main surface of the substrate, using a medium without such an input/output difference. When, (Hc tax - Hc win) /
Hc(0)≦0.9(Here, Hcwax is the maximum value of coercive force, Hczen is the minimum value of coercive force, Hc(0)
We have proposed a magnetic recording medium characterized by having the following relationship: ) represents the coercive force in the longitudinal direction of the substrate.

In this case, the above (Hc mat-Hc win) /H
When c(0) is 0.6 or less, corrosion resistance becomes extremely good, and this fact has also been previously proposed by the present inventors.

In this way, even if we control the coercive force within a given plane,
It has the disadvantage of being insufficient in terms of durability and having poor so-called still characteristics in still image mode.

That is, a magnetic recording medium that has low running friction, no difference in input and output depending on whether the medium is running in the forward or reverse direction, and has very good running durability has not yet been realized.

II. Purpose of the Invention The purpose of the present invention is to improve physical properties such as friction, running durability, and running stability in a metal thin film type magnetic recording medium and a magnetic recording method using the same, and to improve physical properties such as friction, running durability, running stability, etc. The objective is to eliminate head adhesion and clogging to the extent possible, and to ensure that no problems occur in terms of electromagnetic conversion characteristics.
The object of the present invention is to provide a magnetic recording medium and a magnetic recording method that have a small input/output difference and are highly durable in both forward and reverse running directions of the medium.

Such objects are achieved by the invention described below.

That is, the present invention.

The first invention relates to a magnetic recording medium in which a ferromagnetic metal thin S calendar whose main component is Co is provided on a flexible substrate.

When the gap length of the magnetic head is aILe, the medium surface has an average of 105/a2 or more protrusions per 1 mm2, and the protrusions have a height of 30 to 300 people, and furthermore, in the longitudinal direction of the base , when the coercive force of the ferromagnetic metal thin film layer was measured while changing the direction on a plane parallel to the normal to the main surface of the substrate, (Hc wax-Hc 5in
) /Hc(0) ≦ 0 + 9 (Here, Hc
sag is the maximum value of coercive force, Hc is the minimum value of coercive force, and Hc (0) is the coercive force in the longitudinal direction of the substrate. .7 or more.

Further, a second invention provides a magnetic recording method for recording and reproducing a magnetic recording medium in which a ferromagnetic metal thin film layer containing Co as a main component is provided on a flexible substrate using a magnetic head, comprising the steps of: When the gap length is aIL, the surface of the medium has an average of 105/a2 or more protrusions per 2 holes, and the height of the protrusions ranges from 30 to 300.

Furthermore, when the coercive force of the ferromagnetic metal thin film layer was measured while changing the direction on a plane defined by the longitudinal direction of the substrate and the normal direction of the main surface of the substrate, (Hc wax - Hc win
) /Hc(0)≦0.9 (Here, Hc wax is the maximum value of coercive force, Hc sin is the minimum value of coercive force, Hc
(0) represents the coercive force in the longitudinal direction of the substrate) The magnetic recording medium is characterized in that it has the following relationship and the filling factor of one ferromagnetic metal thin film layer is 0.7 or more.

■Specific structure of the invention Hereinafter, a specific configuration of the present invention will be explained in detail.

The magnetic recording medium of the present invention has a ferromagnetic metal thin film layer on a substrate.

The ferromagnetic metal thin film layer in the present invention is Co, Co-Ni, Co-Cr, Co-Ti.

Co-Mo　, Co-V, Co-W.

Co-Re, Co-Ru, Co-Mn.

It may have various known compositions such as Co-Fe, Fe, etc.
As for its formation method, vapor deposition, ion blating, etc. can be used.

However, the effect of the present invention is greatest on C.

as the main component, and Ni and Cr as necessary.

This is a case where the magnetic layer has a composition containing one to three types of O.

That is, it may consist of Co alone;

and Ni.

In the case of Co+Ni, the weight ratio of Co/Ni is
It is preferable that it is 1.5 or more.

Furthermore, in addition to Co or Co+Ni, 0 may be included. When 0 is included, more favorable results can be obtained in terms of changes over time in electromagnetic conversion characteristics and running durability.

In such a case, the atomic ratio of 07Co (if Ni is not included) or O/(Co+Ni) is preferably 0.5 or less, particularly 0.1 to 0.45.

On the other hand, Co and C are contained in the ferromagnetic metal thin film layer.

In addition to +Ni, Co+O or Co+Ni+O, Cr
When it is contained, even more favorable results are obtained.

This is because electromagnetic conversion characteristics are improved, output and S/N ratio are improved, and film strength is further improved.

In such cases, Cr/Co (if Ni is not included)
Alternatively, the weight ratio of Cr/(Co+Ni) is preferably 0.1 or less, particularly o, ooi-o, i.

And Cr/Co or Cr/(Co+Ni)
The weight ratio is 0.005. When it is 0.05, even more preferable results are obtained.

In addition, in such a ferromagnetic metal thin film layer.

Furthermore other trace components, especially transition elements, e.g.

Fe, Mn, V, Zr, Nb, Ta, Ti.

Zn, Mo, W, Cu, etc. may be included.

Such a ferromagnetic metal thin film layer usually has a thickness of 0.05 to 0.
The thickness is preferably 0.07 to 0.3 mm.

Such a ferromagnetic metal thin film layer is usually preferably composed of an aggregate of columnar crystal grains tilted with respect to the normal to the main surface of the substrate.

In such a case, the columnar crystal grains are preferably inclined at an angle of 30''' or more with respect to the normal to the main surface of the substrate.

Further, each columnar crystal grain has a length spanning the entire thickness direction of one ferromagnetic metal thin film layer, and its minor axis is about 50 to 500λ.

It is preferable that the inclination angle of the columnar crystal grains on the substrate side to the normal to the main surface of the substrate is larger than the inclination angle of the columnar crystal grains on the opposite side to the normal to the main surface of the substrate.

Co, Ni, Cr, etc. are present within the crystal grains, and 0 is present mainly on the surface of each columnar crystal grain.

Under this premise, when the coercive force is measured while changing the direction on a plane defined by the longitudinal direction of the substrate and the normal direction of the main surface of the substrate, Hc ax, Hc win, and Hc
(0) means (Hc wax-Hc win) /Hc (0)≦0
．． Must be 9.

If the value exceeds 0.9, a large input/output difference of 2 dB or more will occur when the running direction of the medium is changed, which is not practical.

When this value becomes 0.6 or less, the input/output difference between forward and reverse running becomes extremely small.

Moreover, if this value exceeds 0.6, the corrosion resistance will be critically reduced (1) and it will not be practical.

When this value is 0.4 or less, the input/output difference between forward and reverse running becomes extremely small, and the corrosion resistance becomes extremely high.

Furthermore, the filling factor of one ferromagnetic metal thin film layer must be 0.7 or more.

In this case, the filling factor is expressed as ρ/ρB, where ρ is the average of the 0.7 ferromagnetic metal thin film layer and ρ8 is the true density of the constituent components of the ferromagnetic metal thin film layer.

The average density ρ is the actually measured average density of the entire ferromagnetic metal thin FM calendar.

Further, the true density ρ8 is the bulk density of a homogeneous ingot of an alloy having a composition corresponding to the constituent components of the ferromagnetic metal thin film layer.

To measure ρlpB, first, the weight and volume of the ferromagnetic metal thin film layer are actually measured, and then p is measured.

In this case, one weight is determined by drying and weighing a sample of a certain area and the base used, and calculating the weight from the difference.

In addition, the thickness of the ferromagnetic metal thin film layer when calculating the volume can be determined using a step needle, a film thickness meter, or an electron micrograph.

You can find it from etc.

By dividing this ρ by ρB directly measured from the bulk alloy ingot, ρlρ8 is calculated.

Alternatively, perform fluorescent X-ray analysis, Auger spectroscopy, ESCA, etc. on the ferromagnetic metal thin film layer.

Measure the counts of component elements.

In this case, the ferromagnetic metal thin film layer produced by the oblique evaporation method is
The material has a density gradient in the thickness direction, and counts of fluorescent X-rays and the like are performed while etching is performed using dry process etching means such as ion milling, and the counts are averaged. And even if you divide this count number (average count number) by the count number of the reference ingot,
ρ/ρ8 is calculated.

When ρ/ρB calculated in this way becomes 0.7 or more, the running durability decreases and the still durability time becomes short.

In this case, more favorable results can be obtained when ρ/ρ8 is 0.75 or more, particularly 0.8 or more.

Note that such ρ/ρ8 preferably has a gradient over the thickness direction of the ferromagnetic metal thin film layer.

i.e. by changing the deposition conditions.

The density distribution in the thickness direction of the ferromagnetic metal thin film layer changes, and this also causes a difference in running durability.

In this case, ρ/ρB of the substrate side portion of the ferromagnetic metal thin film layer
It is preferable that the average density is larger than ρ/ρB or the average density of the portion opposite to the substrate.

In this case, when the ferromagnetic metal thin film layer is divided into three equal parts in the thickness direction, ρ or ρ/ρ of 173 parts □ from the side opposite to the substrate.
B is ρ of 1/3 part from the base side or 1 of ρ/ρB
．． It is preferably 5 times or more, preferably 1.5 to 3 times, more preferably 1.5 to 2.5 times.

At this time, running durability is further improved.

It should be noted that if it is greater than 3 times, head touch becomes poor and output fluctuation occurs.

In addition, the average density of each part in this case is, for example, ESC
It may be determined from the characteristic X-ray intensity of the component such as A and the etching time using Ar or the like.

Various types of top coats may be applied to the surface of such a ferromagnetic metal thin film layer as required. Also, the substrate on which the ferromagnetic metal thin film layer is formed is a long and non-magnetic material. There is no particular limitation on the number of publications as long as it is made of a material, and it is particularly preferable to use a flexible substrate, especially one made of resin such as polyester or polyimide.

Moreover, its thickness may be of various thicknesses, but in particular 5.
It is preferable that it is ~20 l.

In this case, on the back side of the ferromagnetic metal thin film layer forming surface of the substrate,
Various known back coat layers may be formed.

Fine protrusions are provided at a predetermined density on the surface of the magnetic recording medium of the present invention constructed as described above.

The fine protrusions are 30 to 300 people, more preferably 50 to 300 people.
It has a height of 250 people.

That is, the protrusions of the present invention are not those that can be observed with an optical microscope and measured with a stylus type surface roughness meter, but are those that can be observed with a scanning or transmission electron microscope.

When the protrusion height exceeds 300λ and becomes observable with an optical microscope, it causes deterioration of electromagnetic conversion characteristics and a decrease in running stability.

Furthermore, if the number of participants is less than 50, there is no effective improvement in physical properties.

And its density is on average 105/12 per 1 fat 2
, more preferably 2 x 10'/a 2~l
Q9/12 pieces.

In this case, a represents the gap length of the magnetic head used in pm.

and a is 0.1-0.5JLm, especially 0.1-0
．． 4pm.

In addition, the protrusion density is 105/a2 pieces/llm2. More preferably, when it is less than 2×10 8 /a 2 pieces/ml I 2 , physical properties such as increased noise, decreased still characteristics, and frequent head clogging occur, and are not suitable for practical use.

Furthermore, if the number exceeds lQ9/a2 pieces/2 mating layers, the effect on physical properties will decrease.

In order to provide such protrusions, it is usually sufficient to arrange fine particles on the substrate.

The diameter of the fine particles may be 30 to 300, particularly 50 to 2-50, so that fine protrusions corresponding to the diameter of the fine particles are formed.

The fine particles used are those commonly known as colloidal particles, such as SiO2 (colloidal silica), A1203 (alumina sol), MgO, and TiO2.
.

Z no-F e203, zirconia, CdO.

NiO, CaWO4, CaCo3.

BaCo3, CoCo3, BaTiO3.

Ti (titanium black) t A u * A g
r CupNi, Fe, various hydrosils, resin particles, etc. can be used. In this case, it is particularly preferable to use inorganic substances.

Such fine particles may be prepared by forming a coating liquid using various solvents, applying this onto a substrate, and drying it, or by applying a coating liquid containing a resin component such as various water-based emulsions, and drying the coating liquid. You may.

Note that, in some cases, protrusions may be provided by adding fine particles to the top coat layer instead of disposing these coating liquids on the substrate.

Furthermore, when a resin component is used, gentle protrusions may be provided to overlap the microprotrusions based on these fine particles; however, this is usually not necessary.

Note that various known underlayers may be interposed between the substrate and the ferromagnetic metal thin film layer, if necessary.

Furthermore, if necessary, the ferromagnetic metal thin film layer may be divided into a plurality of parts, and a non-ferromagnetic metal thin film layer may be interposed between them.

In the present invention, the magnetic layer is formed by electrolytic vapor deposition.

Although ion blasting, plating, etc. can also be used, it is preferable to form by a so-called oblique vapor deposition method.

In this case, the minimum value of the incident angle of the vapor deposition substance with respect to the normal to the substrate is preferably 20° or more.

When the incident angle is less than 20°, electromagnetic conversion characteristics deteriorate.

Usually, during vapor deposition, a cylindrical can for vapor deposition is used, and a vapor deposition mask is interposed in the can, so that the incident angle is 90 to 20 degrees with respect to the normal to the main surface of the substrate. It is preferable to gradually reduce the angle of incidence during the coating.

In such a case, in order to provide the above-mentioned angular dependence of coercive force, for example, in a direction perpendicular to the feeding direction of the substrate, that is, in the width direction of the substrate.

There are methods such as arranging a plurality of hearths or crucibles and changing the evaporation rate.

In addition, in order to set ρ/ρ8 and its distribution to the above values, there are methods such as changing the evaporation rate in the width direction of the substrate as described above and slightly lowering the minimum incident angle during vapor deposition. .

Such condition values can be easily determined through experiments. .

Note that the vapor deposition atmosphere is an inert atmosphere such as argon, helium, vacuum, etc. as usual, and the to-sxtoo P
The pressure may be set to about 100 psi, and the evaporation distance, substrate conveyance direction, structure and arrangement of the can and mask, etc. may be the same as known conditions.

However, oxygen is included in the deposition atmosphere.

It is preferable to improve electromagnetic conversion characteristics, corrosion resistance, etc.

Additionally, for optional magnetism during deposition, oxygen can be introduced into the ferromagnetic metal thin film layer by various methods.

Various acid and chemical treatments can also be performed after forming the ferromagnetic metal thin film layer.

Another ferromagnetic metal thin! ! When heat treatment is performed after layer formation,
Get more favorable results.

On the other hand, various magnetic heads can be used.

In this case, the magnetic head is preferably one in which at least the end face of the gear 2 part is made of a metal magnetic material.

In this case, the entire core may be formed from a metal ferromagnetic material, and if necessary, a portion of the core including the end face of the gap portion may be formed from a metal ferromagnetic material.

1st rj! For example, J has 1 to 5 ru ■ on the end face of the gap part of the core half-hole 21.22 made of ferrite or other ferromagnetic material.
An example is shown in which a magnetic head 1 is constructed by depositing a metal ferromagnetic material 31.degree. 32 of a certain thickness by sputtering or the like, and bringing the core halves 21 and 22 together through a gap 4 made of glass or the like.

As a result, extremely good electromagnetic conversion characteristics can be obtained, and furthermore, the running performance is improved, and head adhesion and head clogging are also improved.

Further, its shape, structure, etc. may be known ones.

However, as mentioned above, the gap length a is usually 0. I
NO,5 layer, especially 0. In addition, the track width is usually 10 to 50 IL, particularly 10 to 20 IL.

Various ferromagnetic materials can be used, and any thin film or plate of amorphous magnetic metal, sendust, hard permalloy, permalloy, etc. can be used.

However, among these, an amorphous magnetic alloy containing Co as a main component has particularly low head clogging or adhesion and has good electromagnetic characteristics.

Examples of such an amorphous magnetic alloy include C.

Zr, Nb as vitrification elements at 70 to 95 at%
, Ta, Hf, rare earth elements, Si.

B, P, C, AM etc., especially Zr and/or Nb 5
Preferably, it contains up to 20 at%.

Alternatively, Co is 65 to 85 at% and Si and/or B is 15 to 35 at% as the glass dead weight element.
Also suitable are those containing in this case.

Furthermore, Fe of 10 at% or less, Ni of 25 at% or less,
A total of 20 at% or less of cr, Ti, and Ru.

One or more of W, Mo, Ti, Mn, etc. may be contained.

These amorphous magnetic alloys are formed as core halves or gap portions using sputtering, high-speed quenching, or the like.

In order to perform recording and reproduction on the above-mentioned medium using such a magnetic head, it is sufficient to follow a known video recording system such as the so-called VH3 system, Beta system, 8-layer video system, U standard system, etc.

■Specific effects of the invention The magnetic recording medium of the present invention is useful as a medium for video, audio, computer use, etc.

According to the present invention, running durability is extremely high and still characteristics are extremely good.

Further, the input/output difference depending on whether the medium runs in the forward or reverse direction becomes extremely small.

Moreover, corrosion resistance is extremely good, and property deterioration is extremely small.

In addition, running friction is extremely reduced and stabilized, further improving running durability, and there is no increase in running friction even after many runs, greatly improving the number of times of repeated recording and playback, and still characteristics are improved. Much improved.

It also has high running stability, exhibiting extremely high stability under a wide range of conditions, from high temperature and humidity to low temperature and low humidity.

Furthermore, the reproduction output due to spacing loss is also extremely small.

Also, noise is extremely low.

In addition, head clogging and head adhesion are extremely rare.

Such an effect becomes even higher when a head made of metal ferromagnetic material is used.

Moreover, such an effect becomes even higher in high-density recording with a minimum recording wavelength of less than 1W layer.

■Specific embodiments of the invention Specific examples of the present invention will be described in detail below.

Example 1 Colloidal silica was coated on a smooth polyester film (thickness l 2 end ya ) substantially free of fine particles to obtain a substrate having microprotrusions having the height and density shown in Table 1.

Next, Co, Co/Nif) weight ratio is 4/
l, and using an alloy with a weight ratio of Co/Ni/Cr of 65/3015, on a polyester film substrate (radius 1001) with predetermined protrusions,
A 0.15-thick magnetic layer M layer was formed by an oblique evaporation method.

The substrate is continuously conveyed in a can, and the incident angle of the vapor deposition material is adjusted to 90°.
It decreased from Also, the distance between the evaporation source and the can is 200
It was set as am.

And the vapor deposition P = 5X10-3Pa, Ar and to this.

P = 2X10-'Pa The test was carried out in an atmosphere containing oxygen.

In this case, the molten metal area of the hearth was set to 25 cm, and a total of three eights were arranged, one at the center of the base and one at two points separated by 20-1 in the width direction of the base.

Among the evaporation rates from these three hearths, the evaporation rate of the corner hearth in the direction of the substrate end is the same, and the ratio of the evaporation rate of the end direction hearth and that of the center hearth is changed as shown in Table 1 below, and the evaporation is carried out. I went.

Furthermore, the minimum incident angle during vapor deposition was changed as shown in Table 1.

then in air for each sample.

Heat treatment was performed at 85° C. for 1 hour.

In each sample, the magnetic layer has a length spanning the entire thickness direction of the magnetic layer, and is composed of an aggregate of columnar crystal grains that are inclined with respect to the normal to the substrate. The angle of inclination was larger than that of the surface layer side portion.

In addition, the amount of oxygen in each sample is O2 introduced into the atmosphere, O/(Co or C).

+Ni), -18 to 20%, without introducing 02,
It was about 1%.

Further, each sample and the substrate used were weighed after drying to measure ρ, and on the other hand, C.

/Ni, Co/Ni/Cr bulk density ρB was measured and ρ/ρ8 was calculated, and the results shown in Table 1 below were obtained.

In addition, the value X obtained by dividing ρ/ρ8 at the 1/3 film thickness part from the surface by ρ/ρ8 at the film thickness 1/3 part from the substrate was calculated by ESCA while performing Ar etching.
The results shown in Table 1 were obtained.

Next, each sample was cut into a 1/2 inch width, and a tape was prepared from the center.

The magnetic head used was the one shown in Figure 1, with a gap length of 0.25g and a track length of ? This is the θw vote. in this case.

The core half-holes 21 and 22 are made of ferrite, and the gap end surface is
CoO, 8N with a thickness of 3 mm formed by sputtering
iO,I ZrO,l (atomic ratio), and the gap material was glass.

Note that 105/a2 is 1.6X1 (l).

Next, the following measurements were performed for each sample.

(1) Input/output difference in forward and reverse running directions Installed in a commercially available VH3 type video deck.

Input and output at 4.5 MHz in both running directions were measured, and the difference between the maximum values was determined.

(2) Corrosion Resistance Each sample was left at 60° C. and 90% relative humidity for 7 days, and −Δφm/φm (%) per cys2 was measured.

(3) Still Durability The time (minutes) required for the output to attenuate to 1/2 at 20° C. and 60% relative humidity was measured using a commercially available VTR device in still mode.

(4) Running durability For each sample, 50 bus experiments were conducted using a commercially available VTR device, and the amount of reduction (dB) in the 4 MHz signal was measured.

These results are shown in Table 1.

From the results shown in Table 1, the effects brought about by the coercive force distribution and filling rate in the present invention are clear.

Example 2 In a sample made of the Co/Ni alloy of Example 1 in an oxygen atmosphere, colloidal silica was applied onto the substrate, and microprotrusions shown in Table 2 below were provided.

In the sample of the present invention, no effect of colloidal silica coating was detected when observed using an optical microscope and measured using a stylus type surface roughness meter, but when observed at high magnification using a scanning electron microscope, protrusions were observed on the magnetic film. It can be seen, and its size is
It corresponded to the size of the applied colloidal silica.

Table 2 shows the relationship between the height and density of the protrusions on the surface of the magnetic layer and the characteristics.
Shown below.

In addition, the characteristics, the shortest recording wavelength is 0. Experiments were conducted using full m signals.

The magnetic head used is shown in FIG. 1, and has a camp length of 0.25 pm and a track length of 204 ta. In this case, the core half-holes 21 and 22 are made of ferrite acid, and the gap end faces are made of 34a thick (7) CoO, 8, NiO, l, ZrO formed by sputtering.
, 1 (at%), and the gap material was glass.

In addition, 105/a2 is 1.8 X10a (mm2)
-'.

Furthermore, a ferrite head was used as a magnetic head for comparison.

The characteristics were measured as follows.

1. Protrusion observation SEM (scanning electron microscope) and TEM (transmission electron microscope) are used 2. Still characteristics Record at 5 MHz and measure still characteristics of reproduction output.

　　10 minutes or more is considered an OK level.

3.S/N ratio when recording and reproducing at an output center frequency of 5MHz (
A modified VH3 VTR showing 5MH
Make it possible to measure up to z.

4. Noise (dB) at 4MHz in measuring noise reproduction output
Measure.

5. Surface condition after durability running test The state of the tape surface after running 50 passes was observed using an optical microscope.

0: No change Δ: Damage to magnetic surface ×: Missing of magnetic layer Note that the surface of the magnetic layer in each of these Examples was found to be covered with an oxide layer of 100 to 200 as a result of Auger spectroscopy.

Note that sample 33 is a magnetic layer that does not contain oxygen, which was deposited in an atmosphere that does not contain oxygen.

In each of the above Examples, colloidal silica was used as the inorganic fine particles, but similar results were obtained using other substances such as alumina sol, titanium black, zirconia, or various hydrosils.

Further, similar results were obtained when a head made using a Co-Fe-Ru-Cr-5t-B amorphous material was used.

Note that when a head made using sendust was used, the effect was less than in the above case.

The combination of the tape and head according to the present invention was superior in terms of physical properties compared to other combinations, the coefficient of friction in each atmosphere was stably low, and it was far superior in terms of running durability.

[Brief explanation of drawings]

FIG. 1 is a front view showing an example of a magnetic head used in the present invention. 1...Magnetic head. 21.22... Core half-day off. 31.32...Metal ferromagnetic material. 4...Gap

Claims (1)

[Claims] (1) In a magnetic recording medium in which a ferromagnetic metal thin film layer mainly composed of Co is provided on a flexible substrate, when the gap length of the magnetic head is a μm, the medium surface is 1 mm^. It has an average of 10^5/a^2 or more protrusions per 2, and the protrusions have a height of 30 to 300 Å, and further, on a plane defined by the longitudinal direction of the base and the normal to the main surface of the base When the coercive force of the ferromagnetic metal thin film layer is measured while changing the direction, (Hcmax-Hcmin)/Hc(0)≦0.9 {here, Hcmax is the maximum value of the coercive force, and Hcmin is the coercive force. The minimum value, Hc(0), represents the coercive force in the longitudinal direction of the substrate. } A magnetic recording medium having the following relationship, wherein the filling factor of the ferromagnetic metal thin film layer is 0.7 or more. (2) (Hcmax-Hcmin)/Hc(0)≦0.
6. The magnetic recording medium according to claim 1, which is No. 6. (3) Claim 1 in which the filling factor is 0.75 or more
The magnetic recording medium according to item 1 or 2. (4) The ferromagnetic metal thin film layer is Co or Co and Ni
, Cr, and O, as the main components. (5) The magnetic recording medium according to any one of claims 1 to 4, wherein the ferromagnetic metal thin film layer contains Ni and has a Co/Ni weight ratio of 1.5 or more. (6) The magnetic recording according to any one of claims 1 to 5, wherein the ferromagnetic metal thin film layer contains Cr and has a weight ratio of Cr/(Co or Co+Ni) of 0.1 or less. Medium. (7) The magnetic recording according to any one of claims 1 to 6, wherein the ferromagnetic metal thin film layer contains O and has an atomic ratio of O/(Co or Co+Ni) of 0.5 or less. Medium. (8) The thickness of the ferromagnetic metal thin film layer is 0.05 to 0.5μ
The magnetic recording medium according to any one of claims 1 to 7, wherein the magnetic recording medium is m. (9) Claim 1 in which the ferromagnetic metal thin film layer comprises an aggregate of columnar crystal grains tilted with respect to the normal to the main surface of the substrate.
The magnetic recording medium according to any one of Items 8 to 9. (10) Claims in which the angle of inclination of the portion of the columnar crystal grain on the substrate side with respect to the normal to the principal surface of the substrate is greater than the angle of inclination of the portion of the columnar crystal grain on the opposite side to the substrate with respect to the normal to the principal surface of the substrate. The magnetic recording medium according to any one of items 1 to 9. (11) The magnetic recording medium according to any one of claims 1 to 10, wherein the average density of the ferromagnetic metal thin film layer on the side opposite to the substrate is higher than the average density on the side of the substrate. (12) When the ferromagnetic metal thin film layer is divided into three equal parts in the thickness direction, the average density of the 1/3 portion on the side opposite to the substrate is 1.5 or more of the average density of the 1/3 portion on the substrate side. A magnetic recording medium according to claim 11. (13) A claim in which the flexible substrate is made of a polymer, fine particles having a diameter of 30 to 300 Å are disposed on the substrate, and a ferromagnetic metal thin film layer is provided thereon. The magnetic recording medium according to any one of items 1 to 12. (14) The magnetic recording medium according to any one of claims 1 to 13, wherein the ferromagnetic metal thin film layer has a ferromagnetic metal oxide layer on its surface. (15) The magnetic recording medium according to any one of claims 1 to 14, wherein a is 0.1 to 0.5 μm. (16) In a magnetic recording method in which a magnetic head is used to perform recording and reproduction on a magnetic recording medium in which a ferromagnetic metal thin film layer mainly composed of Co is provided on a flexible substrate, the gap length of the magnetic head is set to aμm. When the medium surface has an average of 10^5/a^2 or more protrusions per 1 mm^2, and the protrusions have a height of 30 to 300 Å, When the coercive force of a ferromagnetic metal thin film layer is measured while changing the direction on a plane that is parallel to the normal direction of (Hcmax-Hcmin)/
Hc(0)≦0.9 {Here, Hcmax represents the maximum value of coercive force, Hcmin represents the minimum value of coercive force, and Hc(0) represents the coercive force in the longitudinal direction of the substrate. } A magnetic recording method characterized in that the filling factor of the ferromagnetic metal thin film layer is 0.7 or more. (17) The magnetic recording method according to claim 16, wherein at least the end face of the gap portion of the magnetic head is made of a metal ferromagnetic material. (18) The magnetic recording method according to claim 17, wherein the metal ferromagnetic material is an amorphous magnetic alloy containing Co as a main component. (19) The magnetic recording method according to any one of claims 16 to 18, wherein a is 0.1 to 0.5 μm.