JPS62277621A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve recording and reproducing characteristics, corrosion resistance and durability by using a protective layer which contains mixed monomolecular film of a fluorine-contg. org. compd. and org. compd. without contg. fluorine or the cumulative film thereof. CONSTITUTION:A magnetic material layer and the org. protective layer are provided on a substrate. The mixed monomolecular film of the fluorine-contg. org. compd. and the org. compd. without contg. fluorine or the cumulative film thereof is incorporated into the protective layer. Fe, alloy essentially consisting of Co-Ni or the oxide, nitride thereof, etc., are usable for the material of the magnetic material layer 2; the Co-Cr alloy which has a high-density recording characteristic and excellent corrosion resistance or the ferromagnetic film essentially consisting of the Co-Cr alloy is more preferable. The high formation temp. of the Co-Cr alloy film is preferable to improve the coercive force of the Co-Cr alloy film which is the magnetic layer. A polyamide, polyimide resin and more particularly arom. polyimide resin having heat resistance are preferred for the high-polymer substrate. The recording medium having the excellent runnability, durability and environmental resistance is thus obtd.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a thin film deposition type magnetic recording medium for high-density recording that has excellent durability and environmental resistance.

[Conventional technology]

Conventionally, coated magnetic recording media have been widely used, which have a magnetic layer in which fine ferromagnetic particles are uniformly dispersed in a polymeric binder on a non-magnetic support, usually made of a plastic film such as polyester. In recent years, the development of ferromagnetic thin-film magnetic recording media in which a thin film of metal or the like is formed on a non-magnetic support using methods such as base sputtering has been progressing, and some of them have been put into practical use. .

In a magnetic recording medium, the magnetic properties, fin resistance, wear resistance, friction coefficient, and shape (curl, deformation) of the magnetic layer are important factors that influence its performance. The performance factors mentioned above are the material and manufacturing method of the magnetic layer.

It depends on the base film and protective lubricant (or layer).

Regarding magnetic layer materials, ferromagnetic thin film magnetic recording media, which have a high magnetic flux density and can be made thinner, are superior to conventional coated magnetic recording media.

nature is a practical issue. That is, since the Co--Ni alloy itself is not a corrosion alloy and is formed by oblique vapor deposition for the purpose of improving properties, it may have a low density and is easily oxidized. In the case of a Co-Ni alloy film, the surface of the film is oxidized (Japanese Unexamined Patent Publication No. 53-85403 and other publications. A protective layer of compounds and nitrides is provided (Japanese Unexamined Patent Publication No. 57-16713).
4, etc.), applying a rust preventive agent (Japanese Patent Application Laid-Open No. 57-152)
518 Publication etc.) are being considered, but C
Because the o-Ni film itself is thin and has low density,
Sufficient corrosion resistance is not guaranteed.

In addition, a proposal was made to form a protective layer consisting of a monomolecular film of a fatty acid metal salt by the Langmuir-Prodgett method (Japanese Patent Laid-Open No. 61-4
811.9) is also available.

With such a proposal, improvements in weather resistance, durability, and runnability can be obtained.

However, in order to maintain high electromagnetic conversion characteristics, it cannot be said that the durability and runnability are sufficient, and further improvements are desired, especially when putting high-density magnetic recording media using short wavelengths into practical use.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a magnetic recording medium that has excellent recording and reproducing characteristics and has practically sufficient performance in terms of corrosion resistance and durability. .

[Means for solving problems]

The above object is achieved by the present invention as follows.

That is, the structure of the present invention is a magnetic recording male body having a protective layer including a mixed monomolecular film of an organic compound that does not contain boron or a cumulative film thereof on a substrate.

[Effect]

FIG. 1 is a diagram showing a preferred embodiment of the magnetic recording medium of the present invention, in which 1 is a substrate, 2 is a magnetic layer, 3 is an intermediate layer, and 4 is an organic protective layer.

The substrate 1 of the magnetic recording medium of the present invention is as follows.

In addition to glass, aluminum, surface oxidized aluminum, etc., polyester, cellulose, acrylic, polyamide, polyimide, polyamideimide, polyolefin, polyfluoroolefin, polyvinyl chloride, polyvinyl acetate, vinyl chloride/acetic acid are used as polymer support base materials. Vinyl copolymers, polyvinylidene chloride, polycarbonates, phenolic resins, polyetherketones, polyetherketones, polyacetals.

Examples include polyphenylene oxide and polyphenylene sulfide.

The material of the magnetic layer 2 is Fe, an alloy mainly composed of Co-Ni, or an oxide thereof.

Nitride etc. can be used, but Co7Cr alloy or C
A ferromagnetic film containing an o-Cr alloy as a main component is preferred.

In order to obtain a magnetic recording medium with excellent electromagnetic conversion characteristics, it is desirable that the coercive force be large. Co-Cr magnetic layer
In order to improve the holding power of the alloy film, it is preferable that the formation temperature of the Co-Cr alloy film is high (100°C to 300°C), and the polymer base is a heat-resistant polyamide or polyimide resin, especially an aromatic polyimide resin. is good.

In floppy disks and magnetic tapes using these polymeric substrates, it is important from the viewpoint of runnability and head touch that the medium be free from curl.

In order to create a curl-free recording medium, Co-Cr
It is necessary to optimally select the thermal expansion value of the polymer substrate so as to cancel out the thermal stress with the alloy film and the stress generated during film formation.

As the aromatic polyimide membrane (film), paraphenylenediamine/(PPD) is used alone as the diamine component, or PPD and diaminodiphenyl ether (D
ADE), and biphenyltetracarboxylic dianhydride (BPD) as the tetracarboxylic acid component.
An aromatic polyimide membrane (film) obtained by film formation and imidization from a solution of aromatic polyamic acid obtained by copolymerization using A) and pyromellitic dianhydride (PMDA) together. Preferably the thickness is 4g, ~1
00g is useful for recording media.

This base film is PPD as mentioned above.

Three components of BPDA and PMDA or PPD, DA
Since it is formed by copolymerization of four components: DE, BPDA, and PMDA, it not only has excellent heat resistance and tensile elasticity.

By variously adjusting the usage ratio of each component constituting both components, the coefficient of thermal expansion of the obtained aromatic polyimide film can be set to a value that roughly matches the coefficient of thermal expansion of the ferromagnetic material. Furthermore, the tensile elastic constant of the aromatic polyimide membrane can be changed to suit the performance such as stiffness depending on the application.

The polyimide film forming the base film has a coefficient of thermal expansion of approximately 1.0XIO-5 to 3.0x10-5 c
m / cm m / "C, and the tensile elastic constant is about 300 to 1200 Kg/mrrf, especially 325 to
700 Kg/mm', preferably has a secondary transition temperature of about 300°C or higher, particularly 310°C or higher, and, in addition to the above-mentioned performance, has a thermal decomposition onset temperature of about 400'O or higher. , especially above 450°C, and about 2
It can withstand continuous use at temperatures around 50℃.
In addition, the tensile strength in a tensile test is approximately 20 kg/m.
m'' or more, especially about 25 Kg/mrrf or more, and whose elongation at break is about 30% or more, especially 40% or more, exhibits excellent heat resistance when manufacturing magnetic recording media, and can be used at high temperatures. This method is ideal because it allows the formation of a magnetic layer of 100%, prevents curling, and provides a magnetic recording medium with excellent winding unevenness, runnability, and head touch.

In order to make the mechanical and thermal properties suitable for the magnetic recording medium as described above, the diamine component used to produce the aromatic polyamic acid should be about 40 to 95% of the total diamine component. Consisting of two components: PPD in a usage proportion of mol%, especially in the range of 45 to 90 mol%, and DADE in a usage proportion of about 5 to 60 mol%, especially 10 to 55 mol%, based on the total diamine components. is preferable, and the tetracarboxylic acid component for producing the aromatic polyamic acid is preferably about 10 to 10% of the total tetracarboxylic acid component.
BP at a usage rate of 90 mol%, especially 15-85 mol%
DA and about 10 to 90 relative to the total tetracarboxylic acid component
PMDA in a usage proportion of mol %, especially 15 to 85 mol %
It is preferable that it consists of the following.

Furthermore, polyimide films made of these components may contain carbon black, graphite, fine silica powder, fine magnesia powder, titanium oxide, calcium carbonate, and other fillers as necessary to control unevenness on the film surface. It is also possible to cross-wire, and such a polyimide film may be used as the substrate of the present invention.

However, in order to take advantage of the excellent high-density recording properties of the magnetic recording medium of the present invention, the surface roughness of the base according to JISBO601 must be at most 0.05 Bm (Rmax is 0.05 g, m).
It is desirable that

To form a magnetic layer made of a Co-Cr alloy on the aromatic polyimide film described above, known methods such as sputtering and continuous electron beam evaporation can be used. When forming a magnetic layer on the surface of a group polyimide film, the temperature of the film (film formation temperature) is set to about 2
Since the temperature can be raised up to 50° C., a magnetic layer with excellent performance can be easily formed.

The advantage of the Co--Cr alloy as a magnetic recording layer is that it has magnetic anisotropy perpendicular to the film surface, resulting in a perpendicularly magnetized film, and is not affected by demagnetizing fields during short wavelength recording.

In other words, since it is not necessary to make the magnetic layer extremely thin, it is possible to have a film thickness sufficient to obtain high output. Furthermore, since it is not formed by oblique evaporation, the film density is high, and the decrease in magnetic flux density due to thinning of the film is small.Furthermore, the Co--Cr alloy film is excellent as a magnetic recording layer in that it has extremely good corrosion resistance.

The thickness of the magnetic layer 2 made of this Co-Cr alloy is O,1
gm to 2.0 JLm, and in addition to directly forming the magnetic layer on the substrate 1, prior to forming the magnetic layer, corona discharge treatment or other treatment may be applied as necessary to improve adhesion, improve magnetic properties, or for other purposes. Pre-treatment, Ai, Ti.

Cr, Ge, S i 02,,A! Non-magnetic film such as L203, Fe-Ni alloy film, or Co-Z
r, Fe-p-(, Fe-Co-5i-B, etc.) may be provided via a high magnetic permeability film typified by an amorphous film such as Fe-Co-5i-B.

These Co--Cr alloy ferromagnetic thin films can also be formed on both sides of the base 1, if necessary.

Cobalt oxide is preferably used as the intermediate layer 3, and can be formed by sputtering in an inert gas containing oxygen at a predetermined pressure, by vacuum evaporation under diluted oxygen, by physical vapor deposition such as ion blating, or by plasma. By oxidation treatment, C.

A direct deposition or oxide layer is formed on the surface of the -Cr alloy ferromagnetic layer 2.

The intermediate layer 3 prevents adhesion between the magnetic recording layer and the head and is extremely effective in improving wear resistance. The thickness of cobalt oxide R3, which is the intermediate layer, needs to be thick enough to ensure wear resistance, but on the other hand, in order to effectively utilize the high-density recording characteristics of the Co-Cr alloy magnetic layer, spacing is required. A thin car is desirable to reduce loss. Therefore, the thickness of the cobalt oxide layer 3 is desirably 30 to 300 mm, and 5ON150 mm is particularly preferable.

The cobalt oxide layer 3 plays a major role in protecting the magnetic recording layer 2, and is also compatible with metal heads, ferrite heads, etc., and reduces the coefficient of friction of the surface. This effect is particularly remarkable when the outermost part of the cobalt oxide layer is Co3O4.

Furthermore, in order to reduce friction and improve running stability without impairing the high-density recording characteristics of the magnetic recording medium of the present invention, it is very effective to deposit a protective layer 4 made of an organic compound on the surface of cobalt oxide R3. be.

In the present invention, an organic compound having a hydrophilic site and a 1Bli aqueous site in one molecule as an organic protective layer, especially a fluorine-containing organic compound (hereinafter referred to as an amphipathic compound) of an aromatic polyimide film. A protective layer containing a mixed monomolecular film obtained by mixing a fluorine-free organic compound) and a fluorine-free compound (hereinafter referred to as an amphipathic fatty acid derivative) or a cumulative film thereof is formed, and a thin film deposition type magnetic recording medium is produced. I got it.

Examples of such amphipathic fluorine-containing organic compounds include compounds having the structure shown below.

One CF3 (CF2) <-R (@CF3(CF2) m-C=C-C=C-(CH
2) n-Rl■CF3 (CF2)<C00C\CH
2 Regarding the above compounds, k is an integer from 6 to 28, preferably from 8 to 20. Also, m.

Each n is an integer from 0 to 28, and the sum of m and n is 7
~35 integer. Furthermore, among the compounds shown in (1) to (2), some of the fluorine atoms may be replaced with hydrogen atoms, and four examples are shown in (1) to (2).

■CF3 (CH2) 16-R 1YCF3 (CH2) 7-C=C-C=C-(CH
2) aR Examples of amphipathic fatty acid derivatives to be combined with these amphipathic fluorine-containing compounds include compounds having the structures shown below.

■CH3(CH2) K'-R' ■CH3(CH2) m' -C=C-C=C-(CH
2) n'-R'lΦCH3(CH2) <'
Coo-C) (=CH2 For the above compound, k' is 1
It is an integer of 4 to 28, preferably 14 to 20.

Further, m' and n' are each integers of O to 28, and m'
The sum of and n' is an integer from 11 to 35 and is 0 or more ■
, ■, ■~■, R moiety and R' are hydrophilic moieties, -COOH, -CH20H, -5O3H,
-COOCH3゜-CH2SH,-”N ・X-CX
-=C1-, Br-.

I-, BF4″″, PF6-, TCNQ-, T
CNQ2, etc.) can be used.

Furthermore, when combining the amphipathic fluorine-containing compounds of ■ to ■ and the amphipathic fatty acid derivatives of ■ to ■The combination is selected. More preferably.

In these combinations, the less tree-philic substituents are equal (R=R') and the total number of carbon atoms is equal (k
=ni', m=m', n=R') are desirable.

As a method for creating a mixed monomolecular film or a mixed monomolecular cumulative film of the amphiphilic fluorine-containing compound and amphipathic fatty acid derivative shown above, for example, 1. Langmuir-Blodgett method developed by Langmuir et al. , LB method).

The desired amphipathic fluorine-containing compound and amphipathic fatty acid derivative (hereinafter collectively referred to as an amphipathic mixture) are dissolved in a solvent such as chloroform. At this time, an arbitrary mixing ratio can be used.

Next, using the apparatus shown in FIGS. 2(a) and 2(b), a solution of the amphiphilic mixture is spread on the aqueous phase 14 to form the amphiphilic mixture into a film shape.

At this time, when using a compound that accommodates a carboxy group at the terminal of either or both of the amphipathic fluorine-containing compound and the amphipathic fatty acid derivative Shirakawa, the aqueous phase 1
4, a desired metal ion is added in advance, for example, Ag'', Li+, Cu, Na'', K
", Ba2".

Ca2”, Co2”, Cr2”, Cd2”, Mg2”.

Mn2”, Pb2”, Cu2”, Fe2+
, Ni2”.

Zn2”, Co3”, Cr3”, Fe3”, AjL3”
.

By dissolving Ru3'', La3+, etc. and ammonium ions, an amphipathic mixture can be formed as a salt of these in the form of a film.The hydrogen atoms of the carboxyl groups are replaced with these metal ions or ammonium ions. The ratio depends on the pH and ion concentration of the aqueous phase 14, and any ratio can be obtained by adjusting the pH and ion concentration.

Next, to prevent this spread layer from spreading freely on the water phase and spreading too much, a partition plate (or float) 7 is provided to limit the spread area and control the state of aggregation of the membrane material, and to control the aggregation state of the membrane substance, it is Obtain a surface pressure of

By moving the partition plate 7 and reducing the developed area, it is possible to control the aggregation state of the membrane material, gradually increase the surface pressure, and set the surface pressure suitable for producing a cumulative membrane. By gently moving the clean carrier 15 vertically up and down while maintaining this surface pressure, a monomolecular film of the amphipathic mixture is transferred onto the carrier 15. The carrier here refers to a magnetic thin film of Km. In this way, a monomolecular film of the amphiphilic mixture can be formed on the surface oxide layer of the ferromagnetic thin film.A monomolecular film of the amphiphilic mixture is manufactured as described above, and the above operations are repeated. This makes it possible to form a monomolecular cumulative film of the desired cumulative number of amphiphilic mixtures.

In addition to the above-mentioned vertical dipping method, methods such as horizontal deposition method, single rotation cylinder method, etc. can be used to transfer the monomolecular film of the amphipathic mixture onto the carrier. The horizontal adhesion method is a method in which the carrier is brought into horizontal contact with the water surface and transferred, and the rotating cylinder method is a method in which a cylindrical carrier is rotated on the water surface and transferred onto the carrier surface. In the vertical immersion method described above, when a carrier with a woody surface is lifted out of water in a direction across the water surface, a monomolecular film is formed on the carrier with the woody groups of the amphipathic mixture facing toward the carrier. . When the carrier is moved up and down as described above, one monomolecular film of the amphipathic mixture is piled up with each step. Since the direction of the film-forming molecules is reversed between the pulling process and the dipping process, according to this method, a Y-shaped film is formed in which the parent wood group and the hydrophobic group of one amphiphilic mixture face each other between each layer.

In contrast, in the horizontal deposition method, a monomolecular film is formed on the carrier with the hydrophobic groups of the amphipathic mixture facing the carrier side. In this method, there is no change in the orientation of the film-forming molecules even if they are accumulated in all calendars.

An X-shaped film is formed with the hydrophobic groups facing the carrier side.

On the other hand, a cumulative film in which parent wood groups in all layers face the carrier side is called a Z-type film.

The method of transferring the monomolecular layer onto the carrier is not limited to these methods, and when a large-area carrier is used, a method of extruding the carrier from a carrier roll into an aqueous phase may also be used. Furthermore, the orientation of the above-mentioned parent wood groups and @water groups toward the carrier is a general rule, and can be changed by surface treatment of the carrier.

The mixed monomolecular film of the amphiphilic mixture and the mixed monomolecular cumulative film formed on the cobalt oxide layer 3 by the above method are ultra-thin films with a high degree of order (thickness per monomolecular layer, 1
5 to 35 people).

When a protective layer is formed using these films, the influence on electromagnetic conversion characteristics can be significantly reduced. At this time, the cobalt oxide layer 3 which is the base of the organic protective layer has higher hydrophilicity than the Co-Cr magnetic layer 2, and therefore, compared to the case where the organic protective layer is formed on the 'Co-Cr magnetic layer, , it is possible to maintain stronger adhesion.

Furthermore, by subjecting the magnetic thin film on which the protective layer has been formed to heat treatment, vacuum treatment, or light irradiation treatment as necessary, the adhesion between the cobalt oxide layer 3 and the organic protective layer 4 can be further improved, and the organic protective layer can be further improved. It is also possible to create a car with further stabilization. In any case, due to the formation of the above-mentioned protective layer, the electromagnetic conversion characteristics are not essentially degraded and the durability is particularly high.

In addition, a thin film deposition type magnetic recording medium with excellent running properties can be obtained.

The thickness of the protective layer according to the present invention is particularly preferably in the range of 15 to 100 people.

In the Co-Cr alloy ferromagnetic thin film deposited magnetic recording medium of the present invention, a magnetic recording layer is formed on at least one surface of the substrate of the magnetic recording medium, and a magnetic recording layer is formed on the opposite surface as necessary. Depending on the situation, a thin film symmetrical to the surface may be formed as a layer, or it may provide protection, lubricity, reinforcement,
Various back coat layers may be formed for the purpose of supplementing other effective effects.
, Ti, V, Zr.

Co, Nb, Ta, W, Cr
, Si.

Thin films of metals such as Ge, semimetals, or their oxides, nitrides, and carbides, or oxide fine particles, easily slippery fine particles such as calcium carbonate, conductive particles such as carbon and metal powder, and fatty acids, fatty acid esters, etc. Examples include those obtained by kneading and applying a polymer binder such as a thermoplastic or thermosetting resin containing at least one type of lubricant.

As mentioned above, it has excellent surface flatness and a coefficient of thermal expansion of yA.
A magnetic recording medium in which a Co-Cr alloy film is formed at high temperature on a well-defined high-modulus, high-heat-resistant copolymerized polyimide film, a cobalt oxide layer is formed on top of the Co-Cr alloy film, and an organic compound protective layer is further formed on the magnetic recording medium is curled. It is an extremely excellent magnetic recording medium because it has a small magnetic field, excellent high-density recording characteristics, and has practically sufficient performance in terms of abrasion resistance, durability, and environmental resistance.

[Example] The present invention will be explained below with reference to Examples.

Evaluation method of tape> Output frequency characteristics: 0.75MHz, 4.5MHz, 7.5MHz
(1) Record a single signal and measure the playback output.

Still durability test: Measure the change in still playback output over time in environments of 20°C, 65% and 0°C, and define O if the output decreases within 3dB after 20 minutes.

Corrosion resistance test: 50°C, 80% temperature for 1000 hours @*Saturation 81 Decrease in bundle density within 10% is defined as O.

Example 1 In a polymerization pot with an internal volume of 300 tons, 20 moles of 3.3',4.4'-biphenyltetracarboxylic dianhydride, 280 moles of pyromellitic dianhydride, paraphenylenediamine,
70 moles and 4,4'-diaminodiphenyl ether:
A 10 gm thick aromatic polyimide base film was prepared using 30 mol of the raw material.

Various physical properties of this aromatic polyimide film were measured, and as a result, the tensile elastic constant was 490 Kg/mm.
2.Thermal expansion coefficient α100~300℃ is 1.6X10-5
cm/cm/”0, RZ was 80 people.

This aromatic polyimide film is used as a base film, and Co 7 is deposited on the surface of the base film using a continuous magnetic tape film forming device equipped with an electron beam heating device.
After forming a perpendicularly magnetized vapor-deposited film of 8 wt%-Cr22 wt% to a thickness of about 0.44 m at a film-forming rate of 14 m/sec at a base film temperature of 200°C, an argon gas containing 10% oxygen was applied on top of the film. Next, an amphiphilic fluorine-containing compound shown in formula (2); acid was mixed with CF3 (CF2)2 (CH2) in an i:f ratio. zscOOH(1
) CH3 (CH2) tscOOH (2) mixing ratio (m
of L ratio) and dissolved in chlorophorem (a
degree 1mg/mu), then cadmium chloride s7mu 4X10
Aqueous phase 14 containing -4M at pH 6.5 and water temperature 20°C (
Figure 2) The above mixed solution was developed and deposited in the form of a film. After evaporating the solvent, the surface pressure was increased to 30 mN/m. While keeping this surface pressure constant, using the above-mentioned magnetic thin film as a carrier,
The carrier was pulled out of the water in a direction across the water surface at a rate of 1 Oam/min, and a layer-by-layer mixed monolayer of z8-perfluoropropane heptatecanic acid and araginic acid was formed on the carrier. The thus obtained magnetic sheet was heated at 70°C.
After heat treatment was performed for 15 minutes in a constant temperature oven, the film was slit into a layer width of 8.0. The curl of this tape is +<0.1
The amount was as small as mm-1, which caused no practical problems. Attach this tape to an 8mm VTR tape cassette, and
Output frequency characteristics, still durability, 50'C with millimeter video deck! Corrosion resistance tests were conducted at 80% RH.

The results were very good as shown in Table 1.

Example 2 A tape was prepared in the same manner as in Example 1, except that three layers of a 1:1 mixed monomolecular film of 16-perfluoropropane heptanedecanoic acid and arginic acid were accumulated.
The results of performance evaluation are shown in Table 1. As a result, the performance was as good as that of a monomolecular film (single layer).

Example 3 An amphipathic fluorine-containing compound represented by formula (3); perfluorodecanoic acid; and an amphiphilic fatty acid represented by formula (2); t-stearic acid were mixed at a mixing ratio of 1:l (mo
CF3 (CF2) acOOH(3)C) (3(CH
2) 16COOH (4) dissolved in chloroform (
i1 degree 1 mg/mJl).

Thereafter, the mixed solution containing 4XIO-4M manganese chloride at a pH of 7 and a water temperature of 20° C. was spread on the aqueous phase 14 (FIG. 2) to precipitate into a film. After removing the solvent by evaporation, the surface pressure was reduced to 30
mN/m.

A Co--Cr magnetic thin film containing a cobalt oxide film with a thickness of 80 mm was prepared in the same manner as in Example 1 while keeping the surface pressure constant. A one-layer, two-layer mixed monomolecular film of perfluorodecanoic acid and stearic acid was formed on the carrier by pulling it up from water in the transverse direction.

The magnetic sheet thus obtained was subjected to vacuum heat treatment for 5 minutes in a vacuum constant temperature oven at 50°C, and then slit to 8.0 mdgr. The performance of this tape was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 4 113-perfluorodecanoic acid 10.1 shown in formula (5)
2-1 lysocacyinoic acid and to shown in formula (6)
, CF3 (CF2) 4 by mixing with 1.2-octadecacyuic acid at a mixing ratio (moil ratio) of 1:1.
・C=C-C=C-(CH2) a-COOH(5)
CH3(CH2) 4・c=c-C=C-(C
H2) a-COOH (8) dissolved in chloroform (
a degree 1 mg/mu).

This is followed by pH6 containing cadmium chloride 4XIO-4M.
, 5. The mixed solution was spread on the aqueous phase 14 (FIG. 2) at a water temperature of 5° 0 (7) and precipitated into a film. After evaporating the solvent, the surface pressure was increased to 20 mN/m.

A Co--Cr magnetic thin film containing a cobalt oxide film with a thickness of 80 mm was prepared in the same manner as in Example 1 while keeping the surface pressure constant. A 1:1 mixed monomolecular film of 13-perfluoropenta-10,12-tridecaneitic acid and 10.12-octadecaceitic acid was pulled up from the water in a direction transverse to nlIC5F11C=C=C*C. -(CH
2) a-Coo)((CH2) 5cOOH The sample obtained by the above treatment was slit into a width of 8.0 mm. The performance of this tape was evaluated in the same manner as in Example 1.

Disc Evaluation Method Using a still video deck (prototype), playback output and durability were measured for output fluctuations (output unevenness) in the circumferential direction.

Output frequency characteristics: 1.3MHz, 7.0MHz+7) Record a single signal and measure the playback output.

Durability: Reproduction was performed continuously for 50 hours under four conditions at 20° C. and 65%, and the output was rated O if the decrease in output was 6 dB or less.

Output unevenness: Indicates the difference between the maximum and minimum output values in one track.

Example 5 3,3',4,4'-biphenyltetracarboxylic dianhydride; 40 mol, pyromellitic dianhydride; 60
moles, paraphenylenediamine; 50 moles and 4.4'
- Diaminodiphenyl ether: A solution composition of an aromatic polyamic acid was produced in the same manner as in Example 1 using a monomer component consisting of 50 moles and a component ratio. Using the solution composition thus obtained, an aromatic polyimide film having a thickness of 404 m was produced in the same manner as in Example 1.

This aromatic polyimide film has a tensile elastic constant of 400.
Kg/mm2. Thermal expansion coefficient (X100-300℃ is 2.
6X10-5cm/cm/'01Rz was 30 people.

This aromatic polyimide film was used as a base film, and a perpendicularly magnetized film of 80 wt% Co-20 wt% Cr was formed on the base film using a sputtering device in a thickness of about 0.5 m at a temperature of the base film of 150″C. After that, Co was sputtered on top of it in argon gas containing 12% oxygen to form a 100% thick cobalt oxide thin film.Next, the same organic protective layer as in Example 1 was formed by the same method and kept at a constant temperature of 70°C. After heat treatment in a furnace for 1.5 minutes, it was punched into a disc with a diameter of 47mmφ.
Evaluation was performed using a video disc player. The results were very good as shown in Table 2.

Example 6 The organic protective layer in Example 5 was formed by the same method as in Example 4, and was subjected to polymerization treatment by irradiation with a 200W high-pressure mercury lamp. Thereafter, a disk with a diameter of 47 mm was punched out and evaluated using a video disk player. The results are shown in Table 2.

Comparative Example 1 A metal-coated magnetic sheet was punched into a disk with a diameter of 47 mm, and evaluated using a video disk player. The results are shown in Table 2.

Table 1 Table 2 [Effects of the invention] A Co-Cr alloy ferromagnetic thin film is formed by a film deposition method, and an amphiphilic fluorine-containing compound is further applied on the film surface on which a cobalt oxide layer is formed. By laminating protective layers containing amphiphilic fatty acid derivatives, running properties and

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a magnetic recording medium of the present invention, 1...substrate, 2...magnetic layer, 3...intermediate layer, 4...
organic protective layer, 5... aquarium, 6... frame, 7.
...Partition plate, 8...Weight, 9...Pulley, 1
0... Magnet, 11... Pair magnet, 12... Toyokawa pipe, 13... Folding nozzle, , 14... Water phase,
15... Partner (m. 16... Carrier upper and lower arms

Claims (7)

[Claims] (1) In a magnetic recording medium having a magnetic layer and a protective layer on a substrate, the protective layer includes a mixed monomolecular film of a fluorine-containing organic compound and a fluorine-free organic compound, or a cumulative film thereof. A magnetic recording medium characterized by: (2) The magnetic recording medium according to claim 1, wherein the thickness of the protective layer is in the range of 15 to 100 Å. (3) The magnetic recording medium according to claim 1, wherein the substrate is an aromatic polyimide film. (4) The magnetic recording medium according to claim 1, wherein the organic compound is a fatty acid or a derivative thereof. (5) The magnetic recording medium according to claim 1, which has an intermediate layer between the magnetic layer and the protective layer. (6) The magnetic recording medium according to claim 5, wherein the intermediate layer contains cobalt oxide. (7) The magnetic recording medium according to claim 1, wherein the magnetic layer includes a Co-Cr alloy ferromagnetic material.