JPH1139636A - Magnetic recording medium and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide such a magnetic recording medium and its producing method that the deviation of a magnetic head of a device for the magnetic recording medium from the tracks where information is recorded is reduced. SOLUTION: This magnetic recording medium is produced to show the following thermal characteristics. When the medium is heated, the inversion temp. (TI) at which inversion from expansion to contraction of the medium occurs is >100 deg.C, and the max. expansion rate (RE) during heating is >0.1 %. Each of the inversion temp. (TI) and the max. expansion rate (RE) is substantially equal in the longitudinal direction(MD) and in the transverse direction(TD). The nonmagnetic substrate of the magnetic recording medium consists of a film having special treatment layers on the top and back surfaces.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium for recording information such as video, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in the development of magnetic recording media, a coating type magnetic recording medium manufactured by applying a mixture of a binder and γ-iron oxide or Co-coated iron oxide particles has been developed. Have been.

On the other hand, as a development of a magnetic recording medium aiming at higher density of information to be recorded and higher quality of recorded and / or reproduced video, a metal magnetic recording layer is directly formed on a non-magnetic substrate. Metal thin-film magnetic recording media formed by plating, sputtering, vacuum deposition, ion plating, etc., have been developed. The metal thin-film magnetic recording media is used for magnetic recording of digital video equipment for consumer use. It is already commercially available as a medium.

[0004]

However, the above-mentioned magnetic recording medium is anisotropically thermally shrunk and deformed in response to a change in the temperature of an application or an environment in which the medium is stored. The head is displaced from the track on which information is recorded on the medium, the reliability of the signal from the track is reduced, and block noise occurs.
As a result, when recording and / or reproducing a video, the quality of the video may be reduced in the magnetic recording medium. In addition, the durability of the magnetic recording medium may be deteriorated due to damage caused by repeated deformation during an environmental test or the like during running. However, when the signal to be recorded on the magnetic recording medium is an analog video signal, the upper and lower ends of the video can be prevented from being adversely affected by the above-described deviation of the magnetic head from the track. Also, when the signal to be recorded on the magnetic recording medium is an audio signal or when the medium is used for business equipment, the recording density of the information recorded on the medium is low, The negative effects of the shift were not significant.

[0005] However, in a consumer digital video device, since the device uses a magnetic recording medium capable of recording digital video signals at a high density, an adverse effect due to a deviation of a magnetic head from a track appears remarkably.

In order to overcome the adverse effect caused by the deviation of the magnetic head from the track, Japanese Unexamined Patent Publication No. Hei.
No. 612 (heat-treated in a wound state), JP-A-6-2
Although many improvement proposals have been made, such as those described in Japanese Patent No. 00875 (controlling the air flow of a heating furnace), it is still insufficient at present to overcome the adverse effects.

The present invention considers such a conventional magnetic recording medium, in consideration of the problem that the magnetic head of the apparatus that handles the medium deviates from the track on which the information is recorded on the medium, and considers the apparatus that handles the magnetic recording medium. It is an object of the present invention to provide a magnetic recording medium for reducing the deviation of the magnetic head from a track on which information is recorded, and a method for manufacturing the same.

[0008]

According to the present invention, there is provided a magnetic recording medium substrate, a magnetic layer provided on the surface of the substrate and recording information, a protective film for protecting the magnetic layer,
A magnetic recording medium comprising: a lubricating layer formed on the protective film; and a back coat layer provided on the back surface of the substrate, wherein a reversal temperature (T _I ) exceeds 100 ° C. .

According to a second aspect of the present invention, the maximum expansion ratio (R _E )
2. The magnetic recording medium according to claim 1, wherein the content exceeds 0.1%.

According to a third aspect of the present invention, the reversal temperature (T _I ) and the maximum expansion ratio (R _E ) are set in the width direction (T _E ).
3. The magnetic recording medium according to claim 2, wherein D) is substantially equal in the longitudinal direction (MD).

According to the present invention, when the magnetic recording medium according to any one of claims 1 to 7 is manufactured, at least the reversal temperature (T _I ) of the magnetic recording medium exceeds 100 ° C. A method for controlling the tension, heating temperature and processing speed of a magnetic recording medium during a heat treatment.

According to a ninth aspect of the present invention, when the magnetic recording medium according to any one of the second to seventh aspects is heat-treated, the maximum expansion ratio (R _E ) of the magnetic recording medium exceeds 0.1%. 9. The method for manufacturing a magnetic recording medium according to claim 8, wherein at least a tension, a heating temperature, and a processing speed of the magnetic recording medium are controlled.

According to a tenth aspect of the present invention, the inversion temperature (T _I ) of the magnetic recording medium according to any one of the second to seventh aspects is provided.
And at least the tension, heating temperature, and processing speed of the magnetic recording medium so that the maximum expansion ratio (R _E ) is substantially equal in the width direction (TD) and the longitudinal direction (MD) of the magnetic recording medium. 10. The method for manufacturing a magnetic recording medium according to claim 9, wherein the method is controlled during the heat treatment.

According to the present invention, there is provided a magnetic recording medium comprising: a substrate; a surface layer provided on the surface of the substrate; a magnetic layer provided on the surface layer for recording information; A protective film, a lubricating layer formed on the protective film, and a back surface layer provided on the back surface of the substrate and having a non-adhesive property to the surface layer and / or the magnetic layer; And a back coat layer provided on the back surface layer.

According to a twelfth aspect of the present invention, there is provided a magnetic recording medium substrate, a magnetic layer provided on the surface of the substrate and recording information, a protective film for protecting the magnetic layer, and A lubricating layer is formed, a back layer provided on the back surface of the substrate and having a non-adhesive property to the magnetic layer, and a back coat layer provided on the back layer. Magnetic recording medium.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of the magnetic recording medium of the present invention. As shown in FIG. 1, the magnetic recording medium of the present invention includes a non-magnetic substrate 1, a magnetic recording layer 2, a carbon layer 3, a lubricant 4, and a back coat layer 5.

The non-magnetic substrate 1 is made of polyamide, polyimide, polyethylene, polyethylene terephthalate (PE)
T), a polymer film of polyethylene naphthalate (PEN), polybutylene naphthalate, or vinyl chloride. Considering physical properties such as heat resistance, heat shrinkage, surface properties, and mechanical strength, and availability, handling, price, and mass productivity, the nonmagnetic substrate 1 is preferably made of polyethylene terephthalate (PET) or polyethylene. Desirably, it is naphthalate (PEN). Considering the direction of thinning, PEN is advantageous in terms of mechanical strength and heat resistance.
Is most preferable as the non-magnetic substrate 1. In addition, as a thermophysical property value of the nonmagnetic substrate 1, the heat shrinkage rate is in the longitudinal direction (M
D) and the width direction (TD) are preferably small, and the characteristics of the shrinkage and the inversion temperature required by the present invention cannot be achieved with a thinner polyamide.
Is limited to PET or PEN. Even if the polyamide has the same characteristics as the shrinkage and the inversion temperature required for the non-magnetic substrate 1 of the magnetic recording medium of the present invention, the production cost is high, and the polyamide is It is not suitable as a non-magnetic substrate 1 of a magnetic recording medium for a recording device. By the way, the surface property of the non-magnetic substrate 1 is such that the surface of the magnetic recording medium after tape formation has almost no projections and has a smooth surface state in consideration of the signal quality of information recorded on the magnetic recording medium. And At this time, the quality of the image recorded as a digital signal on the magnetic recording medium is improved.

The magnetic recording layer 2 is made of a ferromagnetic metal containing at least one of Fe, Co and Ni, or
n, Cr, Ti, P, Y, Sm, Bi, etc. or an alloy obtained by combining oxides thereof, particularly Co, C
and at least one of r and Ni.
It is formed with a thickness of about μm or less.

The carbon layer 3 is a carbon thin film formed by plasma CVD using a volatile lower hydrocarbon compound as a raw material, and has a thickness of about 100 angstroms.

The lubricating layer 4 is a low molecular lubricant developed in consideration of the bonding property with the carbon layer 3.

The back coat layer 5 is a resin of a mixture paint containing carbon or the like in a binder mainly composed of a polymer material, and has a thickness of about 0.5 μm.

Next, the heat treatment for producing the magnetic recording medium of the present invention will be described. The unit operation of the heat treatment according to the present invention is performed using light source radiation such as ultraviolet, infrared, and electromagnetic waves, and a heating furnace such as an electric furnace, a drying furnace, and a heat exchange furnace. Above all, it is preferable to use a drying furnace in the heat treatment of the present invention in consideration of the necessity of temperature setting, easy control, and industrialization and mass productivity. This is because, when heat is applied to the magnetic recording medium of the present invention, the reversal temperature T _I exceeds 100 ° C., and the maximum expansion ratio R _E is 0.1%.
%, And the reversal temperature T _I and the maximum expansion ratio R _E are substantially equal in the longitudinal direction (MD) and the width direction (TD) of the magnetic recording medium. It is necessary, and the drying oven is
To satisfy the requirements, the tension of the magnetic recording medium,
This is because it is easy to optimize the factors of the heating temperature and the processing speed.

The reversal temperature T _I is the temperature at which the magnetic recording medium of the present invention expands and then reverses to contract when heated, and the maximum expansion ratio R _E is the reversal temperature. The expansion ratio at T _I to the magnetic recording medium before heating.

The reason why it is necessary to optimize the tension of the magnetic recording medium is that if the tension is too high, cracks occur in the width direction of the magnetic recording layer 2, whereas if the tension is too low. This is because there is a problem in winding the magnetic recording medium into a roll.

The reason why it is necessary to optimize the heating temperature of the magnetic recording medium is that if the heating temperature is too low, the heating amount required to be applied to the magnetic recording medium must be increased. The time becomes longer and the processing speed becomes slower. On the other hand, if the heating temperature for the magnetic recording medium is too high, adverse effects may occur on other constituent layers other than the non-magnetic substrate 1 constituting the magnetic recording medium, or a phenomenon may occur in which the non-magnetic substrate 1 extends. is there. In addition, since the tension of the magnetic recording medium is controlled to be appropriate during heating as described above, the change in the elongation (MD) of the non-magnetic substrate 1 in the longitudinal direction (MD) is not particularly limited. If the heating temperature is not appropriate, the stretching effect of the non-magnetic substrate 1 acts.

The thermophysical properties of the magnetic recording medium manufactured in this manner, that is, the reversal temperature T _I and the maximum expansion coefficient R _E are measured by a thermomechanical tester (TMA).

The magnetic recording medium of the present invention manufactured by the above-described manufacturing method and the like has improved thermal deformation, and is more susceptible to temperature changes in the application and the environment in which the medium is stored than the conventional magnetic recording medium. , Because of its excellent surface properties, information can be stably recorded and / or reproduced, and the quality of information such as recorded and / or reproduced video can be improved. Durability has also improved.

Next, the surface properties of the non-magnetic substrate 1 of the magnetic recording medium of the present invention will be described. The non-magnetic substrate 1 undergoes many heat treatments in the manufacturing process. In the conventional non-magnetic substrate 1 having surface properties, projection defects occur due to generation of oligomers and adhesion of the material of the back coat layer 5 during many heat treatments. The signal quality could still be degraded. Therefore, in order to improve the protrusion defect of the non-magnetic substrate 1, a special treatment layer treated with a non-adhesive heat-resistant resin was applied to the front and back surfaces of the non-magnetic substrate 1. As a result, the surface properties of the magnetic recording medium of the present invention were such that there were almost no protrusions on the surface after tape formation, and the magnetic recording medium had a smooth surface state. Therefore, according to the present invention, the quality of digitized video recorded on the magnetic recording medium is improved.

[0030]

Next, embodiments of the present invention will be described in more detail with reference to the drawings.

Example 1 A nonmagnetic substrate 1 having a thickness of 6
μm, 500 mm wide polyethylene terephthalate (P
ET) film, and a metal thin-film type magnetic layer having a thickness of 0.16 μm in which one layer of Co is laminated in an oxygen glow state as a magnetic recording layer 2 thereon, and a resin back coat layer 5 is applied. did. Then, a carbon layer 3 serving as a protective layer is formed by a plasma CVD method, and isopropyl alcohol having 1000 ppm of diperfluoropropyldecyldithioether dissolved therein is applied on the carbon layer 3 to form a lubricating layer 4. Was provided to obtain a magnetic recording medium. Then, this magnetic recording medium was slit into １ ／ inch, stored in a cassette with a length of 60 minutes, and made into a tape.

The above-described magnetic recording medium was heated as described in the embodiment, and the reversal temperature T _I was 120 ° C.
Maximum expansion ratio R _E was obtained 0.15% of the magnetic recording medium. The reversal temperature T _I and the maximum expansion rate R _E are measured by a thermomechanical tester (TMA).

A comparative sample was prepared for comparing the following linear value and shrinkage ratio with the magnetic recording medium having the above-mentioned thermophysical property values (Example 1). The only difference between the comparative sample and the magnetic recording medium of Example 1 is the thermophysical properties. The inversion temperature T _I and the maximum expansion rate R _E of the comparative sample are 85 ° C. and 0.07%, respectively.

[0034] FIG. 2 shows the measurement results of the thermal deformation amount R _E of again heating the comparative sample with the magnetic recording medium of Example 1 were each measured with a thermomechanical tester (TMA).

Next, the linear characteristic will be described. The linear characteristics are as follows. After a magnetic tape (magnetic recording medium) in a cassette state of a DV format is left for 20 hours in an environment of 60 ° C., a deviation of a magnetic head of a device handling the magnetic tape from a track on which information on the magnetic tape is recorded. And a linear value was used as a value indicating the degree of track deviation. Magnetic tapes having a linear value of up to 3 μm are acceptable. In the comparative sample, the linear value was as large as 〜6 μm, the signal from the track decreased, and the block error increased. On the other hand, it was found that the magnetic recording medium of Example 1 had a small linear value of up to 2 μm, that is, the linear value was within the allowable range.

Next, the shrinkage ratio will be described. The shrinkage was measured in each of the longitudinal direction (MD) and the width direction (TD) of the magnetic recording medium after being left at 80 ° C. for 10 hours. The shrinkage of the magnetic recording medium of Example 1 was 35, 2 of the shrinkage of the comparative sample for MD and TD, respectively.
It was about 5%. Thus, it was found that the magnetic recording medium of Example 1 was improved in the shrinkage ratio as compared with the comparative sample.

As described above, as in the magnetic recording medium of the first embodiment, the inversion temperature T _I exceeds 100 ° C.
The magnetic recording medium of the maximum expansion ratio R _E has the thermal properties of more than 0.1% is independent with respect to temperature changes in the environment applications and the media are stored, it was found to be excellent magnetic recording medium .

(Example 2) The thickness of the non-magnetic substrate 1 was 4.8.
A μm polyethylene naphthalate (PEN) film was used. Other configurations of the magnetic recording medium are the same as those of the magnetic recording medium of the first embodiment. As the magnetic recording medium of Example 2, five samples (1) to (5) were prepared by changing the tension, the drying temperature (heating temperature), and the processing speed of the magnetic recording medium during the heat treatment during manufacture. did.

The longitudinal direction (M) of these five magnetic recording media
The measurement results of the inversion temperature T _I and the maximum expansion rate R _E for D) and the width direction (TD), respectively shown in FIG. In FIG. 3, the right end, the center, and the left end of the magnetic recording medium of the samples (1) to (5) of Example 2 are the right end and the center in the width direction of 500 mm in width. , The measurement results at each of the left end portions.

Then, the linear values and the shrinkage ratios of the five magnetic recording media were measured. As a result, in the sample (1) shown in FIG. 3, both the linear value and the shrinkage ratio were not good, and the thermal deformation state was not improved. Although the sample (2) was improved from the sample (1), the MD was not good in the thermal deformation state. In addition, this sample (2) is in the width direction (T
The homogenization of D) was not obtained, and the physical properties were also insufficient. On the other hand, samples (3) to (5) had good physical properties. In the sample (3), the MD was larger than that in the sample (5), and the TD was larger in the sample (5).
Samples (3) and (5) were magnetic recording media containing some distortion. Among the samples (3) to (5), the sample (4) had a small shrinkage rate in both MD and TD, and the ratio was almost the same. Further, the linear value of the sample (4) was 0.5 μm, and the linear characteristics were also good.

Therefore, according to the present invention, the inversion temperature T
_I exceeds 100 ° C., the maximum expansion rate R _E exceeds 0.1%, and their values are isotropic for MD and TD, that is, the reversal temperature T _I and the maximum expansion rate R _E Figure 3
It has been found that the magnetic recording medium that is present in the shaded area and along the isotropic action line in FIG. 3 is the most preferable magnetic recording medium.

(Embodiment 3) The thickness of the nonmagnetic substrate 1 is 4.8.
The configuration of the magnetic recording medium of Example 3 is the same as that of Example 1 or 2, except that a polyethylene naphthalate (PEN) film having a thickness of .mu.m is used, and a special treatment layer is formed on the front and back surfaces of the nonmagnetic substrate 1. This is equivalent to the configuration of the recording medium. The front surface of the non-magnetic substrate 1 refers to one surface of the non-magnetic substrate 1 on which the magnetic recording layer 2 is provided.
The surface of the non-magnetic substrate 1 opposite to the above-described surface.

FIG. 4 is a sectional view of a magnetic recording medium according to the third embodiment. The magnetic recording medium of Example 3 has an acrylic binder-containing front side special treatment layer 6 having a non-adhesive property to the back side special treatment layer 7 on the surface of the nonmagnetic substrate 1.
In addition, a backside special treatment layer 7 containing a fluorine-based polymer and having a non-adhesive property to the front side special treatment layer 6 and the magnetic recording layer 2 is provided on the back surface. The thickness of the surface-side special treatment layer 6 is 50 to 100 Å, and the thickness is measured by infrared spectroscopy.

Then, the magnetic recording medium of Example 3 and the comparative sample used in Example 1 were used for each manufacturing process.
The number of protrusions on the surface was measured and evaluated. In addition, dropout (DO) was also measured and evaluated. Table 1 shows the evaluation results. In addition, the measurement of the number of protrusions on the surface is as follows.
The surface of the transmitted light per unit cm ^{2 of the} measurement object was observed with a microscope, and the number of the transmitted light was counted. The number of drops per minute (DO) was measured at 5 μm and -10 dB per minute.

[0045]

[Table 1]

The center part and the end part in Table 1 show the measurement result at the center part or the end part in the width direction of 500 mm in width of the magnetic recording medium of Example 3 or the magnetic recording medium of the comparative sample. is there.

As shown in Table 1, in the comparative sample, interaction between the front surface and the back surface of the non-magnetic substrate 1 was observed due to the effects of heat radiation, annealing, and the like, and the number of protrusions increased each time the manufacturing process was performed. doing. On the other hand, in the magnetic recording medium of Example 3, it was found that the number of protrusions hardly changed in any manufacturing process.

In comparison with respect to dropout (DO), the magnetic recording medium of Example 3 was 2
It turned out to be about three times better.

Therefore, as in the magnetic recording medium of the third embodiment, the non-magnetic substrate 1 is
When special treatment layers having non-adhesive properties are provided, protrusions and dropouts (DO) are reduced, and a magnetic recording medium provided with such a non-magnetic substrate 1 has high quality. I understood.

Therefore, a magnetic recording medium having high quality and excellent running durability can be provided only after obtaining a magnetic recording medium such as the magnetic recording medium of this embodiment.

In the third embodiment, the surface of the non-magnetic substrate 1 is coated with an acrylic binder-containing surface-side special treatment layer 6.
In addition, the back surface of the non-magnetic substrate 1 is provided with a back side special treatment layer 7 containing a fluorine-based polymer, and the front side special treatment layer 6 is non-adhesive to the back side special treatment layer 7. The back side special treatment layer 7 has the property of being non-adhesive to the front side special treatment layer 6 and the magnetic recording layer 2, but the back side special treatment layer 7 has Only one of the side special processing layer 6 and the magnetic recording layer 2 may be non-adhesive. The surface of the nonmagnetic substrate 1 may not be provided with the surface-side special treatment layer 6 containing an acrylic binder. In this case, the backside special treatment layer 7 only needs to have a non-adhesive property to the magnetic recording layer 2.

In the present invention, it is desirable to use polyethylene terephthalate (PET) or polyethylene naphthalate (PEN) for the non-magnetic substrate 1. However, the present invention relates to a magnetic recording medium on which information is recorded at a high density. In order to increase the volume recording density, the use of PEN for the non-magnetic substrate 1 is intended to provide a magnetic recording medium in which the deviation of the magnetic head of the device handling the medium from the track of the medium is improved. The effect of the present invention is greatest.

The deviation of the magnetic head from the track, which is an object of the present invention, does not cause much problem in a magnetic recording medium having a low volume recording density and a large thickness.
In other words, in a magnetic recording medium in which the total thickness of the magnetic recording medium is 6 μm or less and which is thin and requires some measures to obtain sufficient rigidity, the problem of the deviation of the magnetic head from the track becomes significant. In other words, with respect to a magnetic recording medium in which the stiffness in the width direction (TD) is made higher than the stiffness in the longitudinal direction (MD) to ensure contact between the magnetic recording medium and the magnetic head, there is a problem of deviation of the magnetic head from the track. Becomes noticeable. Therefore, the magnetic recording medium of the present invention has a thickness not exceeding 6 μm and / or a width direction (TD).
When the rigidity is higher than the rigidity in the longitudinal direction (MD), the effect is greatly exhibited.

Although the magnetic recording layer 2 (magnetic layer) is formed by vacuum deposition, sputtering or the like, the magnetic recording layer 2 (magnetic layer) may be formed by a coating method. However, the present invention relates to the solution of the adverse effect of the deviation of the magnetic head from the track in a magnetic recording medium in which the non-magnetic substrate 1 is given a thermal history and the magnetic recording layer 2 is formed, such as a vacuum evaporation method or a sputtering method. Would be particularly beneficial.

In the present invention, a non-magnetic substrate 1 as a substrate, a magnetic recording layer 2 as a magnetic layer, a carbon layer 3 as a protective film, a front side special processing layer 6 as a surface layer, and a back side special processing layer 7 as a back layer. Was used.

[0056]

According to the present invention, the inversion temperature T _I of 100
℃ exceeded, also, the magnetic recording medium where the maximum expansion rate R _E has the thermal properties of more than 0.1%, further, a magnetic recording medium which inversion temperature T _I and the maximum expansion rate R _E is isotropic,
Alternatively, a magnetic recording medium having a surface property without protrusions exhibits the following effects 1) to 3), and also exhibits a constant high S / N characteristic without running property and lack of output signal.

1) Even when the ambient temperature changes, the isotropic thermal characteristics of the medium act to suppress the shrinkage. Therefore, the magnetic recording medium of the present invention has improved thermal characteristics and stable information Can be recorded and / or reproduced.

2) Since the property of thermal deformation is improved,
ADVANTAGE OF THE INVENTION The magnetic recording medium of this invention improves the linear characteristic by temperature change, and can record and / or reproduce information stably.

3) By using a non-magnetic substrate having a special treatment layer on the front and back surfaces, projections on the front surface are scarcely observed, so that the magnetic recording medium of the present invention has no running property and no loss of output signal. , And a certain high S / N characteristic can be exhibited.

Accordingly, the magnetic recording medium of the present invention can record and / or reproduce information stably even when the environmental temperature changes, and has excellent quality and durability.

As described above, the present invention can provide a magnetic recording medium and a method for manufacturing the magnetic recording medium, which reduce the deviation of the magnetic head of the device that handles the magnetic recording medium from the track on which information is recorded.

[Brief description of the drawings]

FIG. 1 is a sectional view of a magnetic recording medium of the present invention.

[Figure 2] in again to the comparative sample with the magnetic recording medium of Example 1 were each heated, thermal deformation of R _E thermomechanical tester (TM
Thermal deformation _RE measurement diagram showing the measurement results measured in A)

FIG. 3 shows reversal temperatures T _I of five magnetic recording media of Example 2.
Of maximum expansion coefficient R _E

FIG. 4 is a sectional view of the magnetic recording medium of the present invention having a special processing layer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Non-magnetic substrate 2 Magnetic recording layer 3 Carbon layer 4 Lubrication layer 5 Back coat layer 6 Front side special processing layer 7 Back side special processing layer

Claims (17)

[Claims] 1. A substrate of a magnetic recording medium, a magnetic layer provided on a surface of the substrate and recording information, a protective film for protecting the magnetic layer, and a lubricating layer formed on the protective film. ,
A back coat layer provided on the back surface of the substrate,
A magnetic recording medium having a reversal temperature (T _I ) exceeding 100 ° C. 2. The magnetic recording medium according to claim 1, wherein the maximum expansion ratio (R _E ) exceeds 0.1%. 3. The magnet according to claim 2, wherein the inversion temperature (T _I ) and the maximum expansion ratio (R _E ) are substantially equal in the width direction (TD) and the longitudinal direction (MD). recoding media. 4. The magnetic recording medium according to claim 1, wherein said magnetic layer is a metal thin film. 5. The magnetic recording medium according to claim 1, wherein said substrate is made of polyethylene terephthalate or polyethylene naphthalate. 6. The magnetic recording medium according to claim 1, wherein the thickness of the magnetic recording medium does not exceed 6 μm. 7. The rigidity in the width direction (TD) is determined in the longitudinal direction (M).
The magnetic recording medium according to any one of claims 1 to 6, wherein the rigidity is higher than D). 8. The method of manufacturing a magnetic recording medium according to claim 1, wherein at least the tension of the magnetic recording medium is adjusted so that the reversal temperature (T _I ) of the magnetic recording medium exceeds 100 ° C. And a heating temperature and a processing speed are controlled during the heat treatment. 9. When the magnetic recording medium according to claim 2 is heat-treated, at least magnetic recording is performed so that the maximum expansion ratio (R _E ) of the magnetic recording medium exceeds 0.1%. 9. The method for manufacturing a magnetic recording medium according to claim 8, wherein the tension, heating temperature, and processing speed of the medium are controlled. 10. The magnetic recording medium according to claim 2, wherein the reversal temperature (T _I ) and the maximum expansion ratio (R _E ) are different from the width direction (TD) and the longitudinal direction of the magnetic recording medium. In the direction (MD), at least the tension, heating temperature, and processing speed of the magnetic recording medium are set so as to be substantially equal.
The method for manufacturing a magnetic recording medium according to claim 9, wherein control is performed during the heat treatment. 11. A substrate for a magnetic recording medium, a surface layer provided on the surface of the substrate, a magnetic layer provided on the surface layer for recording information, and a protective film for protecting the magnetic layer. A lubricating layer formed on the protective film, a back surface layer provided on the back surface of the substrate, and having a non-adhesive property to the surface layer and / or the magnetic layer; A magnetic recording medium comprising: a provided back coat layer. 12. A substrate of a magnetic recording medium, a magnetic layer provided on the surface of the substrate and recording information, a protective film for protecting the magnetic layer, and a lubricating layer formed on the protective film. A magnetic recording medium, comprising: a back surface layer provided on the back surface of the substrate and having a non-adhesive property to the magnetic layer; and a back coat layer provided on the back surface layer. 13. The magnetic recording medium according to claim 11, wherein said surface layer has a thickness of 50 to 100 Å. 14. The magnetic recording medium according to claim 11, wherein said magnetic layer is a metal thin film. 15. The magnetic recording medium according to claim 11, wherein said substrate is made of polyethylene terephthalate or polyethylene naphthalate. 16. The magnetic recording medium according to claim 11, wherein the thickness of the magnetic recording medium does not exceed 6 μm. 17. The rigidity in the width direction (TD) is determined in the longitudinal direction (M).
The rigidity is higher than D).
7. The magnetic recording medium according to any one of 6.