JPH10105944A - Magnetic recording media - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use a thin base film having a thickness of 4.5 μm or less as a non-magnetic support of a magnetic recording medium, and to perform recording by running the magnetic recording medium in both forward and reverse directions. Also provided is a magnetic recording medium that exhibits the same running performance in the forward direction and the reverse direction even when performing reproduction, has excellent running stability, and realizes good head touch. SOLUTION: In a magnetic recording medium having a magnetic layer having a single or two or more column structure formed on a non-magnetic support by oblique vapor deposition, a surface opposite to the magnetic layer of the non-magnetic support is formed by vapor deposition. It has a back coat layer consisting of at least two thin films formed, and in the thin film, the inclination of the column of the layer farthest from the nonmagnetic support and the inclination of the column of the layer adjacent thereto are opposite to each other. A magnetic recording medium characterized by being inclined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deposition type magnetic recording medium, and more particularly to a back coat layer. More specifically, the present invention relates to a magnetic recording medium in which a back coat layer is formed of at least two thin films and the structure of the thin films is controlled, whereby good running properties can be realized and head touch is further improved.

[0002]

2. Description of the Related Art Conventionally, a backcoat layer is formed on a surface of a nonmagnetic support opposite to a magnetic layer so as to have the following three functions. (1) By providing conductivity, adhesion of dust is prevented by an antistatic effect. (2) Running stability is obtained by controlling surface properties (coefficient of friction). (3) From the viewpoint of hardness and the like, the surface having the magnetic layer and the back surface having the back coat layer are balanced to prevent the occurrence of warpage.

[0003] As a method of forming the back coat layer, carbon having a particle size of 10 to 100 nm is dispersed in a binder (using a vinyl chloride-based, urethane-based, or nitrified cotton-based material alone or as a mixture), and the gravure method or the reverse method Conventionally, a method of applying a die coating method so that the thickness after drying becomes 0.4 to 1.0 μm, or a method of depositing a metal or metalloid in a vacuum vessel has been conventionally performed. In the method of forming the back coat layer by coating, the method (1) is performed by controlling the conductivity of carbon, the method (2) is controlled by controlling the particle diameter of the carbon and the coating process, and the method (3) is performed by controlling the coating process. By controlling the binder and the coating thickness, each was satisfied. However, due to the presence of the binder, the back coat layer could not obtain sufficient conductivity, and the magnetic layer was damaged because the medium had to be taken out to the atmosphere once when applying the back coat layer due to the influence of the solvent of the binder. There is a problem that the number of dropouts increases in the dropout inspection due to contamination, dirt, or adhesion of dust.

On the other hand, in the method of depositing a metal in a vacuum, the influence of the binder can be avoided, so that the conductivity of the back coat layer can be improved and the number of dropouts can be reduced. However, it is not possible to obtain sufficient conductivity when depositing a metalloid,
Also, when a metal is deposited, there have been problems in that the surface of the back coat layer becomes too smooth, it is difficult to provide the back coat layer with sufficient hardness, and the end face of the medium is deformed in a wavy manner. To solve the above problems, the present applicant has proposed a method of improving the conductivity of a back coat layer by vacuum-depositing a metalloid and an impurity in Japanese Unexamined Patent Publication No. Hei 7-1995.
Japanese Patent Application Laid-Open No. 98830/98 proposes that a back coat layer is made of two or more layers of metal or metalloid to impart appropriate surface properties and elasticity. Japanese Patent Application Laid-Open No. H8-1010 proposes that the back coat layer has sufficient hardness by forming
Japanese Patent Application Laid-Open No. Hei 8-102051 discloses a proposal in Japanese Patent Application Laid-Open No. Hei 8-102051 that a diamond-like carbon layer is formed on a back coat layer to suppress deformation of an end face of a magnetic recording medium.

[0005]

It is desired to produce a high quality magnetic recording medium with high productivity in the future. However, in the method of forming the back coat layer by coating as described above, a sufficient conductivity is required. This is disadvantageous in that it is difficult to obtain the desired characteristics and the number of dropouts cannot be reduced. The surface property or hardness of the back coat layer was also improved by the above-mentioned proposal in the method of vapor deposition, but further suppression of cupping, improvement in running stability and head touch were desired, so the surface property of the back coat layer was further improved. Alternatively, improvement in hardness has been desired. Also, when performing bidirectional recording and reproduction on a magnetic recording medium, it has been desired that the magnetic recording medium has the same running property in both the forward direction and the reverse direction. In the future, the thickness of magnetic recording media will tend to be smaller in order to store more information in a container of a fixed size, and the magnetic layer and back coat layer formed on a non-magnetic support It has become necessary to control the rigidity of the recording medium. Therefore, in the present invention, in view of the conventional problems as described above, and for the future, in a magnetic recording medium having a magnetic layer formed by oblique deposition, the back coat layer is formed from at least two thin films, Further, by controlling the structure of the thin film, a higher running stability is realized in both the forward direction and the reverse direction, and a magnetic recording medium in which the head touch is further improved by further controlling the rigidity is obtained. The purpose is to:

[0006]

Means for Solving the Problems For this reason, the present inventors have:
In a magnetic recording medium having a magnetic layer having a column structure formed by oblique vapor deposition, a back coat layer is formed from a thin film having at least two column structures obliquely vapor-deposited on a surface opposite to a magnetic layer on a nonmagnetic support. And at least two layers forming the backcoat layer by forming the thin film layer and the layer farthest from the nonmagnetic support in such a manner that the inclinations of the columns of the layer and the layer adjacent thereto are opposite to each other. It has been found that the above object can be achieved by controlling the thickness of the thin film, and the present invention has been completed.

The back coat layer obtained by the present invention is formed on the surface opposite to the magnetic layer having the column structure formed on the non-magnetic support by oblique vapor deposition. It is characterized by comprising at least two layers of thin films inclined so that the inclination of the column of the layer farthest from the magnetic support and the column of the layer adjacent to the magnetic support are opposite to each other. Here, the structural analysis of a plane parallel to the longitudinal direction of the non-magnetic support and perpendicular to the surface of the non-magnetic support is evaluated by observation with a transmission electron microscope (TEM) photograph or by electron beam diffraction. Further, the back coat layer is evaporated by irradiating a metal or metalloid with an electron beam in a vacuum chamber, and the metal or metalloid obtained by attaching the metal or metalloid on a nonmagnetic support or oxides, nitrides, Formed by carbide. Various metals can be attached as the back coat layer.
u, Zn, Sn, Ni, Ag and the like and alloys thereof are used, and Cu-Al alloy is particularly preferable from the viewpoints of price, deposition rate, and stability after oxidation. Further, as the semimetal that adheres as the back coat layer, Si, Ge, As, Sc, Sb, or the like is used, and Si is particularly preferable in terms of cost and adhesion speed. Furthermore, it is also preferable to perform any one of oxidation, nitridation, and carbonization simultaneously when depositing these metals or metalloids to form an oxide film, a nitride film, and a carbonized film. The thickness of the back coat layer is set to be smaller than the thickness of the magnetic layer by 2,000 mm in consideration of the rigidity balance with the magnetic layer formed on the surface of the nonmagnetic support opposite to the back coat layer. It is formed so as to have a thickness 2000 mm thicker than the thickness of the layer. The back coat layer may be formed on the non-magnetic support either before or after the formation of the magnetic layer and the protective layer on the non-magnetic support.

[0008] As the nonmagnetic support used in the present invention, polyethylene terephthalate (PET) is preferable from the viewpoint of cost. However, polyesters such as polyethylene naphthalate, polyolefins such as polyethylene and polypropylene, cellulose derivatives such as cellulose triacetate and cellulose diacetate, and plastics such as polycarbonate, polyvinyl chloride, polyimide, and aromatic polyamide can also be used. The thickness of these non-magnetic supports is generally considered to be about 50 μm, but from the practical point of view in the future, it is preferably 4.5 μm or less. The thickness is preferably 6.0 μm or less from the thickness of the nonmagnetic support and the thickness of each of the constituent layers.

In the present invention, the metal thin film type magnetic layer is formed by ordinary methods such as vapor deposition and sputtering. Examples of the magnetic material for forming the metal thin film type magnetic layer include ferromagnetic metal materials used for manufacturing a normal metal thin film type magnetic recording medium. For example, a ferromagnetic metal such as Co, Ni, Fe or the like, or Fe-Co, Fe-Ni, Co-Ni, Fe-Co
-Ni, Fe-Cu, Co-Cu, Co-Au, Co-
Y, Co-La, Co-Pr, Co-Gd, Co-S
m, Co-Pt, Ni-Cu, Mn-Bi, Mn-S
b, Mn-Al, Fe-Cr, Co-Cr, Ni-C
and ferromagnetic alloys such as r-Fe-Co-Cr and Ni-Co-Cr. Particularly, from the viewpoint of the magnetic properties of the magnetic material used for the magnetic recording medium, at least one selected from a ferromagnetic alloy mainly composed of Co, Ni, and Fe and a nitride or carbide thereof is preferable. By introducing an oxidizing gas at the time of vapor deposition to form an oxide layer on the surface of the magnetic layer, the durability of the magnetic layer can be improved. The magnetic layer formed by vapor deposition may be a single layer or a multilayer of two or more layers, but is preferably a multilayer for high-density recording, and a practical range of two to three layers is appropriate. Further, it is preferable that the magnetic layer of the magnetic recording medium is formed on the non-magnetic support by oblique vapor deposition. However, the method of oblique vapor deposition is not particularly limited, and follows a conventionally known method. The thickness of the metal thin-film magnetic layer is not limited, but is preferably 500 to 5000 °, and particularly preferably 800 to 3000 ° as a practical range. In the case of two layers, the lower layer is preferably about 200 to 2000 °, the upper layer is preferably about 100 to 1000 °, and in the case of three layers,
The lower layer is about 200 to 2000 mm, the middle layer is 200 to 200
The upper layer is preferably about 0 ° and the upper layer is preferably about 100 to 1000 °.

For the purpose of improving the durability and corrosion resistance of the magnetic recording medium, a protective layer of a high hardness thin film can be provided on the magnetic layer and the back coat layer. Such a protective layer is made of a non-magnetic material such as carbide, nitride, or oxide such as diamond-like carbon, boron carbide, silicon carbide, boron nitride, silicon nitride, silicon oxide, or aluminum oxide. The film is formed by the PVD method.

A lubricating layer made of an appropriate lubricant may be formed on the protective layer on the magnetic layer and the back coat layer or on the protective layer on the magnetic layer and the protective layer on the back coat layer. The lubricating layer may be formed by applying a solution obtained by dissolving a lubricant in an appropriate solvent, or may be formed by spraying the lubricant in a vacuum. As the lubricant, a fluorine-based lubricant such as perfluoropolyether is preferable from the viewpoint of lubricity, in either case of application or spraying,
For example, perfluoropolyether has a molecular weight of 200
Those having 0 to 5000 are preferred. The amount of the lubricant to be applied or sprayed is appropriately determined depending on the use of the magnetic recording medium and the type of the lubricant.
It is about 00 °.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of an apparatus suitable for manufacturing a magnetic recording medium of the present invention is shown in a vapor deposition apparatus 1 in FIG.
Here, a vacuum chamber 2 connected to a vacuum evacuation device (not shown), a cooling can roll 3 provided in the vacuum chamber 2, and a nonmagnetic support 4 such as a PET film running on the cooling can roll 3. Including a take-up roll and a take-up roll. A crucible 7 is disposed below the cooling can roll 3 as an evaporation source, and a back coat forming material, for example, a Cu-Al alloy is accommodated in the crucible 7. An electron gun 8 is arranged in the vacuum chamber 2 and irradiates the crucible 7 with an electron beam to evaporate the Cu-Al alloy in the crucible 7. Crucible 7
Above this, deposition-prevention plates 9 and 9 ′ for limiting the angle of incidence of the Cu—Al alloy vapor from the crucible 7 evaporated by the electron beam toward the cooling can roll 3 to the nonmagnetic support 4 are obliquely deposited. It is arranged so that it can be performed. Further, nozzles 10 and 10 'for supplying oxygen gas are disposed immediately above the deposition-preventing plates 9 and 9', respectively.

Using such a vapor deposition apparatus 1, a magnetic recording medium according to the present invention, for example, a backcoat layer as shown in FIG. 2 (a) having a structure in a plane parallel to the longitudinal direction and perpendicular to the surface of the nonmagnetic support. The method for manufacturing a magnetic recording medium having a column structure in which columns of two layers of thin films forming the above-described structure are inclined in directions opposite to each other is as follows. That is, after the inside of the vacuum chamber 2 is set to a predetermined degree of vacuum by the vacuum exhaust device,
The non-magnetic support 4 is moved from the roll 5 onto the cooling can roll 3. At this time, the non-magnetic support may be either a magnetic layer and a protective layer formed on the magnetic layer in advance, or a non-magnetic support having no magnetic layer formed thereon. However, if the magnetic layer is formed by oblique evaporation in advance, and if a protective layer is further formed on the magnetic layer, when the first-layer evaporation is performed, the nonmagnetic support is set down, and the magnetic layer is set up. The magnetic layer must be run so that the column tilts forward with respect to the running direction of the nonmagnetic support. The electron gun 8 irradiates the crucible 7 with an electron beam, and the Cu-
The Al alloy is melted and evaporated, and evaporation is performed on the non-magnetic support 4. This is done in the presence of oxygen supplied from nozzles 10 and 10 '. The non-magnetic support 4 thus treated is once wound on a roll 6. Subsequently, the nonmagnetic support wound on the roll 6 is transferred to the roll 5, and a second layer is deposited. When depositing the second layer, the inclination of the column of the magnetic layer when the non-magnetic support is down and the magnetic layer is up is opposite to the direction of travel of the non-magnetic support 4 when the first layer is deposited. Run the vehicle so that it leans backward. As in the case described above, the electron gun 8 irradiates the crucible 7 with an electron beam to melt and evaporate the Cu-Al alloy in the crucible 7, and vapor-deposits the non-magnetic support 4. This is done in the presence of oxygen supplied from nozzles 10 and 10 '. The treated non-magnetic support 4 is taken up again by the roll 6. A protective layer is formed on the back coat layer if necessary. The protective layer is formed by forming a high-hardness thin film such as diamond-like carbon by CVD or PVD as described above. Further, when the protective layer is formed on the magnetic layer and the magnetic layer in advance, if necessary, the lubricating layer is immediately formed on the protective layer on the magnetic layer and the uppermost layer on the back coat layer side. In the case where the magnetic layer is not formed, at least one magnetic layer is formed by oblique evaporation, a protective layer is formed thereon, and then the protective layer on the magnetic layer and the uppermost layer on the back coat layer side are formed. Form a lubricating layer. As described above, the formation of the lubricating layer is performed by applying a fluorine-based lubricant in the air or spraying it in a vacuum. After the formation of the necessary layers is completed, slitting, wrapping, assembling into a cassette, and the like are performed by a general method.

[0014]

【Example】

Example 1 A nonmagnetic film in which two metallic cobalt magnetic layers were formed on a 4.5 μm-thick PET film by oblique vapor deposition with a total thickness of 1800Å, and a diamond-like carbon film was formed thereon as a protective layer with a thickness of 130Å. A support was provided. On this non-magnetic support, a back coat layer composed of two thin films was formed on the surface of the non-magnetic support opposite to the magnetic layer using the vapor deposition apparatus 1 of FIG. In this back coat layer,
Films were formed such that the inclination of the columns of the two thin films forming the back coat layer were different from each other and opposite to each other. When forming the first layer, the inside of the vacuum chamber 2 is set at 2 × 10 ⁻⁵ Torr.
After evacuating to a vacuum, the electron gun 8 irradiates the Cu-Al alloy in the crucible 7 with an electron beam at an output of 30 kW to form a vapor atmosphere, and the non-magnetic support 4 passes from the roll 5 on the cooling can roll 3 to the roll. 6, the first thin film of the back coat layer was formed on the cooling can roll 3. At this time, the traveling speed of the non-magnetic support 4 is 20 m / min.
And During film formation, oxygen gas was introduced at 110 SCCM from the nozzles 10 and 10 ', respectively. When forming the second layer, the inside of the vacuum chamber 2 is 2 ×
After evacuating to 10 ⁻⁵ Torr, the Cu—Al alloy in the crucible 7 is irradiated with an electron beam at an output of 30 kW by an electron gun 8 to make a vapor atmosphere, and the nonmagnetic support 4 is
, And passed over the cooling can roll 3 to the roll 6 to form a second thin film of the back coat layer on the cooling can roll 3. At this time, the running speed of the nonmagnetic support 4 was set to 15 m / min. At the time of film formation, oxygen gas was introduced at 120 SCCM from the nozzles 10 and 10 ′, respectively. Further, both surfaces of the protective layer and the back coat layer on the magnetic layer were coated with a fluorine-based lubricant so that the thickness of the lubricating layer was 30 ° to form a lubricating layer. 8m obtained
It was cut to a width of m and loaded into a cassette to make an 8 mm video cassette. The cross section of the obtained magnetic recording medium and the structure of the back coat layer are as shown in FIG. 2A according to a TEM photograph or an electron beam diffraction. The inclinations were opposite to each other, and the thickness of both columns increased as the distance from the nonmagnetic support increased. The thickness of the back coat layer was 1000 ° for the first layer and 1300 ° for the second layer.

Example 2 On the same non-magnetic support as in Example 1, a backcoat layer composed of two thin films was formed on the surface opposite to the magnetic layer of the non-magnetic support using the vapor deposition apparatus 1 of FIG. Formed. In this back coat layer, the two thin film layers forming the back coat layer were formed so that the columns had different inclinations in opposite directions. When forming the first layer, the inside of the vacuum chamber 2 is
After evacuation to × 10 ^-5 Torr, the electron gun 8 irradiates the metal Al in the crucible 7 with an electron beam at a power of 30 kW to form a vapor atmosphere, and the nonmagnetic support 4 is moved from the roll 6 onto the cooling can roll 3. Street, run to roll 5,
On the cooling can roll 3, the first thin film of the back coat layer was formed. At this time, the traveling speed of the nonmagnetic support 4 was set to 20 m / min. During film formation, the nozzles 10 and 1
Oxygen gas was introduced at 110 SCCM from 0 ′. In forming the second layer, the inside of the vacuum chamber 2 is evacuated to 2 × 10 ⁻⁵ Torr in the same manner as the first layer, and then the electron beam is applied to the metal Al in the crucible 7 by the electron gun 8 at an output of 30 kW. Irradiation was performed to form a vapor atmosphere, and the nonmagnetic support 4 was passed from the roll 6 to the roll 5 through the cooling can roll 3 to be run, and a second thin film of the back coat layer was formed on the cooling can roll 3. . At this time, the non-magnetic support 4
The running speed was 120 m / min. At the time of film formation, oxygen gas is supplied by 110
M introduced. Further, both surfaces of the protective layer and the back coat layer on the magnetic layer were coated with a fluorine-based lubricant so that the thickness of the lubricating layer was 30 ° to form a lubricating layer. The obtained one was cut into a width of 8 mm and loaded into a cassette to prepare an 8 mm video cassette. The cross section of the obtained magnetic recording medium and the structure of the back coat layer are as shown in FIG. 2 (b) according to a TEM photograph or electron beam diffraction, and the column of the two-layer thin film forming the back coat layer is formed. The inclinations were opposite to each other, and the thickness of both columns became thinner as the distance from the nonmagnetic support increased. The thickness of the back coat layer is 1000Å for the first layer and 100 for the second layer.
It was 0 °.

Example 3 On the same non-magnetic support as in Example 1, a back coat layer composed of two thin films was formed on the surface opposite to the magnetic layer of the non-magnetic support by using the vapor deposition apparatus 1 of FIG. Formed. In this back coat layer, the two thin film layers forming the back coat layer were formed so that the columns had different inclinations in opposite directions. When forming the first layer, the inside of the vacuum chamber 2 is
After evacuation to × 10 ⁻⁵ Torr, the Cu—Al alloy in the crucible 7 is irradiated with an electron beam at an output of 30 kW by an electron gun 8 to form a vapor atmosphere, and the nonmagnetic support 4 is moved from the roll 5 to the cooling can roll 3. After passing over the roll 6, the first thin film of the back coat layer was formed on the cooling can roll 3. At this time, the traveling speed of the nonmagnetic support 4 was set to 20 m / min. At the time of film formation, oxygen gas was introduced at 120 SCCM from the nozzles 10 and 10 ′, respectively. When the second layer is formed, the inside of the vacuum chamber 2 is evacuated to 2 × 10 ⁻⁵ Torr in the same manner as the first layer.
Cu-Al in crucible 7 at output 30 kW by electron gun 8
The alloy is irradiated with an electron beam to form a steam atmosphere, and the nonmagnetic support 4 is passed from the roll 5 to the roll 6 through the cooling can roll 3 and is moved to the roll 6. A thin film was formed. At this time, the traveling speed of the nonmagnetic support 4 was set to 20 m / min. During film formation,
Oxygen gas is supplied from the nozzles 10 and 10 'respectively.
Introduced by SCCM. Further, a fluorine-based lubricant is applied to both sides of the protective layer and the back coat layer on the magnetic layer so that the thickness of the lubricant layer is 3.
Coating was performed so as to be 0 ° to form a lubricating layer. The obtained product was cut into 8 mm width, loaded into a cassette,
A mm video cassette was made. The cross section of the obtained magnetic recording medium and the structure of the back coat layer are as shown in FIG. 2C according to the TEM photograph or the electron beam diffraction, and the column of the two-layer thin film forming the back coat layer is shown in FIG. The inclinations were opposite to each other, and the thickness of both columns increased as the distance from the nonmagnetic support increased.
The thickness of the back coat layer was 1000 ° for the first layer and 1000 ° for the second layer.

Comparative Example 1 On the same non-magnetic support as in Example 1, a back coat layer was formed on the surface of the non-magnetic support opposite to the magnetic layer using the vapor deposition apparatus 11 of FIG. 2 × 10 in vacuum chamber 12
After evacuation to ^-5 Torr, electron beam was applied to the metal Al in the crucible 17 by the electron gun 18 at an output of 30 kW to form a vapor atmosphere. The non-magnetic support 4 was moved from the unwinding roll 15 to the take-up roll 16 through the cooling can roll 13 to form a back coat layer on the cooling can roll 13. The running speed of the non-magnetic support 4 was 10 m / min. At the time of forming the back coat, oxygen gas was introduced from the nozzle 20 at 210 SCCM. Further, both surfaces of the protective layer and the back coat layer on the magnetic layer were coated with a fluorine-based lubricant so that the thickness of the lubricating layer was 30 ° to form a lubricating layer. The obtained one was cut into a width of 8 mm and loaded into a cassette to prepare an 8 mm video cassette. The back coat layer of the obtained magnetic recording medium was TEM
According to the photograph or the electron beam diffraction, it was formed from a thin film having a mixed structure of a random structure and a column structure. The thickness of the back coat layer was 2000 °.

Performance Evaluation The envelope characteristics of the output waveforms of the magnetic recording media obtained in Examples and Comparative Examples were measured by using a device modified from a commercially available 8 mm VTR device. Although the envelope characteristic waveform as shown in FIG. 4A is ideal, the waveform is actually chipped as shown in FIG. Here, the envelope characteristic was obtained by subtracting, from the 100%, the higher chipping rate of the front chipping or the rear chipping at the time of measurement.

The running performance of the magnetic recording media obtained in the examples and comparative examples was evaluated based on the coefficient of friction. The coefficient of friction is measured as follows. That is, temperature 2
At a temperature of 0 ° C. and a humidity of 50% RH, a magnetic tape is wound around a SUS pin having a diameter of 2 mm and a surface roughness of 0.2 S by 90 ° with a tension of 0.1 N from the unwinding side.
The tape is fed at a speed of 18.8 mm / s. The tension is also measured on the winding side, and the friction with the friction pin is calculated from the ratio with the tension on the unwinding side according to Euler's equation to determine the friction coefficient of the magnetic recording medium. The coefficient of friction was measured by running the magnetic recording medium in two directions, a forward direction and a reverse direction. Table 1 shows the results.

[0020]

[Table 1]

[0021]

According to the present invention, in a magnetic recording medium that performs bidirectional recording and reproduction, the same running characteristics can be obtained regardless of whether the magnetic recording medium runs in either the forward direction or the reverse direction. In addition, good head touch can be realized in either direction.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of an apparatus that can be used for manufacturing a magnetic recording medium of the present invention.

FIG. 2 is a model diagram showing a structure of a surface of a magnetic recording medium obtained by the present invention, the surface being parallel to the longitudinal direction of the non-magnetic support and perpendicular to the surface of the non-magnetic support.

FIG. 3 is a schematic view of an apparatus used for manufacturing a conventional magnetic recording medium.

FIG. 4 is a model diagram showing a missing rate of an envelope waveform.

[Explanation of symbols]

 1, 11, vacuum evaporation apparatus 2, 12, vacuum chamber 3, 13, cooling can roll 4, non-magnetic support 5, 6, roll 7, 17, crucible 8, 18, electron gun 9, 9, 19 ', 19' 10, 10'20 nozzle 15, unwinding roll 16, take-up roll

Claims (7)

[Claims] In a magnetic recording medium having a magnetic layer having a single or two or more column structure formed on a non-magnetic support by oblique vapor deposition, at least a surface of the non-magnetic support opposite to the magnetic layer is provided. The backcoat layer consisting of two thin films is formed by vacuum deposition, and the tilt of the column of the layer farthest from the nonmagnetic support of the thin film forming the backcoat layer and the column of the adjacent layer are in opposite directions. A magnetic recording medium characterized by the fact that the magnetic recording medium is tilted. 2. The magnetic recording medium according to claim 1, wherein the back coat layer is a metal or metalloid, or one of an oxide, a nitride, and a carbide of the metal or metalloid. 3. The metal constituting the back coat layer is A
The magnetic recording medium according to claim 2, wherein the magnetic recording medium further comprises l. 4. The film thickness Tbc of the back coat layer and the film thickness Tm of the magnetic layer have a relationship represented by the following equation.
The magnetic recording medium according to any one of claims 1 to 3, wherein Tbc = Tm ± 2000Å 5. The magnetic recording medium according to claim 1, wherein a lubricating layer exists on the back coat layer. 6. The magnetic recording medium according to claim 1, wherein a protective layer and a lubricating layer are present on the back coat layer. 7. The magnetic recording medium according to claim 1, wherein the thickness of the nonmagnetic support is 4.5 μm or less, and the total thickness of the magnetic recording medium is 6.0 μm or less.
The magnetic recording medium according to any one of claims 1 to 6, wherein