JP2001143244A - Magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease a friction coefficient and to improve a traveling property and durability. SOLUTION: The standard deviation of the adhesive force between a lubricating layer 5 and a probe of the magnetic recording medium 1, which is deposited with at least a magnetic metallic film 3 on one main surface of a nonmagnetic base 2 and has the lubricating layer 5 of the outermost layer on the one main surface on the side formed with the magnetic metallic film 3, is specified to >=0.06.

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, and more particularly to a magnetic recording medium having a lubricant layer on an outermost layer on one main surface on which a metal magnetic film is formed.

[0002]

2. Description of the Related Art Magnetic recording media include audio tapes,
It is widely used as video tapes, backup data cartridges, hard disks and the like. As this magnetic recording medium, a so-called coating type magnetic recording medium in which a magnetic layer containing a very fine ferromagnetic powder and a binder containing a binder is coated on a non-magnetic support and dried to form a magnetic layer, Alternatively, a so-called thin-film type magnetic recording medium in which a magnetic layer is formed by applying a ferromagnetic metal material on a nonmagnetic support by a method such as evaporation is used.

In particular, recently, studies on shortening the recording wavelength or high-density recording such as a digital recording method have been actively conducted, and the development of a magnetic recording medium having excellent electromagnetic conversion characteristics has been demanded.

For example, in a coating type magnetic recording medium which is currently mainstream, thinning of a magnetic layer is being studied in order to improve electromagnetic conversion characteristics. This is a method for improving the electromagnetic inspection characteristics by reducing the self-demagnetization loss at the time of recording. In recent years, various coating methods have been proposed.

[0005] In these magnetic recording media, the surface of the magnetic layer is smoothed in order to minimize spacing loss. In high-density recording, since the recording wavelength used is short, it is easily affected by the surface roughness, and control of the surface roughness is particularly important.

As described above, as the high-density recording progresses, it is necessary to make the surface of the magnetic layer of the magnetic recording medium extremely smooth.

However, the better the smoothness of the surface of the magnetic layer, the larger the substantial contact area with a sliding member such as a magnetic head or a guide roller. Therefore, a magnetic recording medium having a good magnetic layer surface smoothness has a large friction coefficient, is likely to cause an adhesion phenomenon (so-called sticking) with a sliding member during running, and lacks running properties and durability. And more problems.

In order to solve these problems, use of various lubricants has been studied. Conventionally, higher fatty acids and esters thereof have been added internally to the magnetic layer of the magnetic recording medium, or Attempts have been made to reduce the coefficient of friction by, for example, topcoating the magnetic layer.

On the other hand, in a magnetic recording device having a magnetic recording medium represented by a hard disk and a recording and / or reproducing magnetic head as main components, a frictional force is generated between the magnetic recording medium and the magnetic head. However, this causes wear damage to the magnetic recording medium and the magnetic head. When the wear damage reaches the magnetic layer of the magnetic recording medium, the information recorded on the magnetic layer is destroyed, that is, a so-called head crash phenomenon occurs, which causes the durability of the magnetic recording medium to deteriorate. Therefore, to prevent head crash,
This is important for ensuring the reliability of the magnetic recording device.

In order to prevent head crash, it is necessary to improve the wear resistance of the magnetic recording medium itself. For this reason, the magnetic layer is usually covered with a protective layer made of carbon, oxide, carbide, nitride, etc. Further, a lubricating film is formed on the protective layer. Such a lubricating film generally requires characteristics such as low surface energy, heat resistance, chemical stability, and lubricity. US Pat. No. 3,778,308 discloses a compound for forming a lubricating film. The perfluoroalkyl polyether-based or perfluoroalkyl compounds described in the specification are currently most frequently used.

[0011]

By the way, it is considered that the surface abundance of the lubricant on the magnetic recording medium greatly affects the practical characteristics including the friction coefficient. When the amount of the lubricant present on the surface is small, the lubricant existing between the magnetic recording medium and the sliding member such as the magnetic head is small, so that the function of the lubricant cannot be sufficiently exhibited. When the amount of the lubricant present on the surface is large, sticking occurs between the magnetic recording medium and a sliding member such as a magnetic head regardless of the material of the lubricant, that is, the friction coefficient tends to increase.
This tendency is particularly noticeable in a room temperature liquid lubricant, and is caused by a meniscus force generated between a magnetic recording medium and a sliding member such as a magnetic head.

However, when the amount of the lubricant is too large, the coefficient of friction tends to increase. However, during running of the magnetic recording medium, the lubricant is expected to decrease due to detachment, decomposition, and the like. In consideration of the life of the medium, it is desirable that as much lubricant as possible exists within a range where sticking does not occur.

Therefore, it is preferable that as much lubricant as possible exists on the magnetic recording medium in order to improve durability while maintaining good running properties of the magnetic recording medium.

Needless to say, there is an appropriate range for the surface abundance of the lubricant, but recent studies have revealed that the appropriate range varies depending on the purpose of use. That is, in AV (Audio-Visual) applications requiring still durability, etc., the so-called helical scan method, the magnetic head repeatedly slides in the same place, so that the lubricant is used as much as possible without sticking to the magnetic head. It is preferable to increase the abundance. On the other hand, when used for so-called data storage, such as data storage and backup, the magnetic head does not slide repeatedly in the same place and mainly runs on the shuttle, so a large amount of lubricant is necessarily required. On the contrary, from the viewpoint of suppressing deposits on the magnetic head, it is preferable that the number is smaller than that in the case of AV applications. As described above, the lubricant existing on the surface of the magnetic recording medium needs to have its surface design, that is, the surface abundance and distribution of the lubricant controlled to an optimum range according to the purpose of use.

Here, the optimum conditions for forming the lubricant, that is, the optimum abundance, differ depending on the melting point, the polar group, the molecular weight and the like of the material constituting the lubricant, and therefore differ depending on the lubricant used. However, the optimum condition for forming the lubricant on the surface of the magnetic recording medium has not been established.

Accordingly, the present invention has been proposed in view of the conventional circumstances, and provides a magnetic recording medium having a low coefficient of friction, excellent in running properties and durability, regardless of the material of the lubricant. The purpose is to:

[0017]

According to the present invention, there is provided a magnetic recording medium comprising at least a metal magnetic film formed on one main surface of a non-magnetic support and one of the non-magnetic support having the metal magnetic film formed thereon. In a magnetic recording medium having a lubricant layer on the outermost layer of the main surface, the standard deviation of the adhesive force between the lubricant and the probe is 0.06 or more.

In the magnetic recording medium according to the present invention, the standard deviation of the adhesive force between the lubricant and the probe is 0.06 or more.
Therefore, the coefficient of friction between the magnetic recording medium and the sliding member can be kept low. As a result, the magnetic recording medium has excellent running properties and durability.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a magnetic recording medium to which the present invention is applied will be described with reference to the drawings.

A magnetic recording medium 1 to which the present invention is applied has a structure shown in FIG.
As shown in the figure, the non-magnetic support 2 and the non-magnetic support 2
A metal magnetic film 3 formed on one principal surface of
It comprises a protective film 4 formed thereon and a lubricant layer 5 formed on the protective film 4. Here, the lubricant layer 5 does not need to be formed on the entire surface of the metal magnetic film 3, and may be formed in an island shape on the metal magnetic film 3, for example.

Hereinafter, the nonmagnetic support 2, the metal magnetic film 3, the protective film 4, and the lubricant layer 5 will be described in order.

Non-magnetic support 2 When the magnetic recording medium 1 is a coating type magnetic recording medium, the non-magnetic support 2 is made of polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate, polypropylene and the like. Polymer materials such as polyolefins, celluloses such as cellulose triacetate and cellulose diacetate, vinyl resins, polyimides, polyamides, polycarbonates, and polyphenylene sulfide can be suitably used.

When the magnetic recording medium 1 is a thin-film type magnetic recording medium, the same non-magnetic support 2 as in the case of a coating type magnetic recording medium can be used. In addition, light metals such as aluminum alloys and titanium alloys, and ceramics such as alumina glass can also be used. When a rigid substrate such as an aluminum alloy plate or a glass plate is used for the nonmagnetic support 2,
An oxide film such as alumite treatment or a Ni-P film may be formed on the surface of the substrate to harden the surface.

The thickness of the non-magnetic support is 1.0 to 2
00 μm, more preferably 2.
0 to 100 μm.

Metallic Magnetic Film 3 When the magnetic recording medium 1 is a coating type magnetic recording medium, the metallic magnetic film 3 is a layer mainly composed of a ferromagnetic powder and a binder. Is formed by applying a magnetic paint obtained by kneading the compound with a solvent onto a non-magnetic support. Here, as the magnetic powder, γ-Fe ₂
O ₃ , Fe ₃ O ₄ , a beltride compound of γ-Fe ₂ O ₃ and Fe ₃ O ₄ , Co-containing γ-Fe ₂ O ₃ , Co-containing Fe
Belt compound of γ-Fe ₂ O ₃ containing Fe ₃ O ₄ and Co and Fe ₃ O ₄ , CrO ₂ containing one or more metal elements, for example, Te, Sb, Fe, Bi, etc. Is mentioned.

Further, metals such as Fe, Co and Ni, Fe
-Co, Fe-Ni, Fe-Co-Ni, Fe-Co-
B, Fe-Co-Cr-B, Mn-Bi, Mn-Al,
Fe-Co-V, Fe-Al, Fe-Ni-Al, Fe
-Al-P, Fe-Ni-Si-Al, Fe-Ni-S
i-Al-Mn, Fe-Mn-Zn, Fe-Ni-Z
n, Co-Ni, Co-P, Fe-Co-Ni-Cr,
Examples include alloys such as Fe-Co-Ni-P and ferromagnetic metal powders such as iron carbide and iron nitride.

Such a ferromagnetic metal powder is obtained by a method of reducing the above-mentioned metal element oxides, hydrated oxides, inorganic salts, organic acid salts and the like in a gas phase with a reducing gas or by a method of wet reduction. be able to. In producing the ferromagnetic metal powder, an appropriate amount of a light metal element such as Al, Si, P, or B may be added for the purpose of preventing sintering during reduction or maintaining the shape.

Also, after reduction, a method of impregnating and drying with an organic solvent, a method of immersing in an organic solvent and blowing and drying an oxidizing gas, a method of blowing an oxidizing gas having a partial pressure adjusted without using an organic solvent, and the like. Thereby, a thin oxide film is formed on the surface to impart oxidation stability. The oxide film formed on the surface includes not only the constituent elements of the metal or alloy described above, but also Al, Si, Ca, Mg, Sr, Ba, B, S, and T.
i, Zn, Na, Zr, K, Y, La, Ce, Pr, N
It may contain d, Sm, Gb, Ge, Sn, Ga and the like.

Further, as the magnetic powder, besides the above-mentioned oxides and ferromagnetic metal powders, hexagonal plate-like ferrite can be used. As the hexagonal plate-like ferrite, M-type, W-type, Y-type, Z-type barium ferrite,
Examples include strontium ferrite, calcium ferrite, and lead ferrite. In order to control the holding power of these hexagonal plate-like ferrites, Co-T
i, Co-Ti-Zn, Co-Ti-Nb, Co-Ti
A material to which -Zn-Nb, Cu-Zr, Ni-Ti, or the like is added can also be used.

These magnetic powders may be used alone or in a combination of two or more.

The size of the magnetic powder is preferably set as follows.

The specific surface area of the magnetic powder is preferably 35 m ² / g or more. By setting the specific surface area to this range, the magnetic powder is made into very fine particles. By forming a metal magnetic film using fine magnetic powder, high-density recording becomes possible and noise can be reduced.

In particular, when the magnetic powder is acicular particles, the major axis length is 0.05 to 0.50 μm and the axial ratio is 2 to 1.
It is preferably 5. When the major axis length is less than 0.05 μm, it becomes difficult to disperse the magnetic powder in the coating material.
And when the major axis length is larger than 0.50 μm,
Noise may increase. On the other hand, when the axial ratio is less than 2, the orientation of the magnetic powder is reduced, and the output is reduced. When the axial ratio is larger than 15, the short-wavelength signal output decreases.

When the magnetic powder is plate-like ferrite, the plate diameter is 0.01 to 0.5 μm and the plate thickness is 0.00.
It is preferably from 1 to 0.2 μm.

As the binder used for the metal magnetic film,
For example, conventionally known resins such as a thermoplastic resin, a thermosetting resin, a reactive resin, and a mixture thereof can be used, and those having a number average molecular weight of 5,000 to 100,000 can be suitably used.

Examples of the thermoplastic resin include vinyl chloride,
Vinyl acetate, vinyl propionate, vinyl alcohol,
Maleic acid, acrylic acid, acrylic acid ester, methacrylic acid, methacrylic acid ester, vinylidene chloride, acrylonitrile, methacrylonitrile, styrene, methylstyrene, butadiene, ethylene, vinyl butyral, vinyl acetal, vinyl ether, vinyl pyrrolidone, etc. A polymer or a copolymer can be used. As the copolymer, for example, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylate-acrylonitrile copolymer,
Acrylate-vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylate-vinylidene chloride copolymer, methacrylate-vinylidene chloride copolymer, methacrylate-vinyl chloride copolymer , Methacrylate-ethylene copolymer, acrylate-styrene copolymer, methacrylate-acrylonitrile copolymer, methacrylate-vinylidene chloride copolymer,
Methacrylic acid ester-styrene copolymer, vinylidene chloride-acrylonitrile copolymer, acrylonitrile-
Butadiene copolymer, polyvinyl butyral, styrene butadiene copolymer, styrene-butadiene copolymer,
Chlorovinyl ether-acrylate copolymers and the like can be mentioned. In addition to the above, polyvinyl fluoride, polyamide resin, cellulose acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose derivatives such as nitrocellulose, polyester resin, polyurethane resin, amino resin, various rubber resins, etc. Can also be exemplified.

The thermosetting resin or the reactive resin includes, for example, phenol resin, epoxy resin, polyurethane curable resin, urea resin, melamine resin, alkyd resin, acrylic reaction resin, formaldehyde resin, silicone resin, polyamine Resins, urea-formaldehyde resins, epoxy-polyamide resins, mixtures of polyester resins and polyisocyanate prepolymers, mixtures of polyester polyols and polyisocyanates, and mixtures of polyurethanes and polyisocyanates.

Further, a polar functional group may be introduced into all of these binders for the purpose of improving the dispersibility of the pigment component. The polar functional _group, -SO _{3 M,} -OSO 3
M, -COOM, P = O (OM) _{2 and the} like. Here, M is a hydrogen atom or an alkali metal such as lithium, potassium, and sodium. Also, -NR1R2,
-NR1R2R3 ⁺ X ^- side chain amine having terminal groups,
Alternatively, a main chain amine represented by> NR1R2 ⁺ X ⁻ can be used. Here, R1, R2, and R3 represent a hydrogen atom or a hydrocarbon group, and X ^- is a halogen element ion such as fluorine, chlorine, bromine, and iodine, an inorganic ion, and an organic ion. Further, as the polar functional group, -OH,
—SH, —CN, an epoxy group and the like. These polar functional groups are preferably contained in the bond in the range of 10 ^-8 to 10 ^-1 mol / g, more preferably ¹ to 10 ^-1 mol / g.
0 ^-6 to 10 ^-2 mol / g.

The above-mentioned binders may be used alone or in combination of two or more.

The magnetic powder and the binder described above are dispersed in a solvent to form a magnetic coating material. Examples of the solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, and the like.
Ketone solvents such as diisobutyl ketone and cyclohexanone; alcohol solvents such as methanol, ethanol, propanol, butanol and isopropanol; ester solvents such as methyl acetate, ethyl acetate, butyl acetate, propyl acetate, ethyl lactate and ethylene glycol acetate; diethylene glycol Ether solvents such as dimethyl ether, 2-ethoxyethanol, tetrahydrofuran and dioxane; aromatic hydrocarbon solvents such as benzene, toluene and xylene; and halogenated hydrocarbon solvents such as methylene chloride, ethylene chloride, carbon tetrachloride, chloroform and chlorobenzene. Solvents, water and the like can be mentioned.

Incidentally, a lubricant, an abrasive, a hardener, a dispersant, an antistatic agent, a rust inhibitor and the like may be added to the magnetic paint as needed. Any of these can be made of conventionally known materials, and is not particularly limited.

As an abrasive, aluminum oxide (α,
β, γ), silicon carbide, chromium oxide, iron oxide, corundum, diamond, silicon nitride, titanium carbide, titanium oxide such as rutile and anatase, garnet, emery, boron nitride and the like.

The abrasive preferably has a Mohs hardness of 4 or more, more preferably 5 or more. The specific gravity is preferably 2 to 6, more preferably 3 to 6.
5 Further, the average particle size is preferably 0.5 μm or less, more preferably 0.3 μm or less. The amount of the abrasive added is preferably not more than 20 parts by weight, more preferably not more than 10 parts by weight, based on 100 parts by weight of the magnetic powder.

As the antistatic agent, carbon black can be suitably used. By adding an antistatic agent, an effect of improving the strength of the coating film can be obtained.

As the dispersant, various surfactants or various coupling agents can be used.

Examples of the curing agent include alkylene diisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate;
Examples thereof include bifunctional isocyanate compounds such as xylene diisocyanate, naphthalene diisocyanate, and isophorone diisocyanate, or a polymer of these diisocyanates and a reaction product thereof with a polyhydric alcohol. The amount of the curing agent added is 5 to 80 parts per 100 parts by weight of the binder.
Parts by weight, more preferably 10 to 5 parts by weight.
0 parts by weight. As the rust inhibitor, conventionally known materials can be used, for example, phenols, naphthols,
Quinones, heterocyclic compounds containing a nitrogen atom, heterocyclic compounds containing a sulfur atom, and the like can be used.

The magnetic coating material is formed into a coating material through the above-described material kneading step, mixing step, and dispersion step. As a kneading device and a dispersing device, a roll mill, a ball mill, a sand mill, an agitator, a kneader, an extruder, a homogenizer, an ultrasonic disperser, and the like can be used.

The magnetic coating material thus prepared is applied to the non-magnetic support 2 by a conventionally known method such as spraying or roll application, and dried to form the metal magnetic film 3. You. After the metal magnetic film 3 is formed, the surface of the metal magnetic film 3 may be smoothed by a calender.

Here, the metal magnetic film 3 preferably has a dry thickness of 0.1 to 50 μm, more preferably 1.0 to 30 μm. The mixing ratio of the binder and the magnetic powder was such that the magnetic powder was 1 to 1 part by weight with respect to 1 part by weight of the binder.
0 parts by weight, more preferably 3 to 9 parts by weight.
Parts by weight. When the amount of the binder is large, the metal magnetic film 3
The proportion of the magnetic powder in becomes relatively small,
Output drops. Further, when the magnetic head and the various sliding members are repeatedly slid on the drive, plastic flow easily occurs in the metal magnetic film 3, and the durability of the magnetic tape is reduced. If the amount of the binder is small, the metal magnetic film 3 becomes brittle, and the durability of the magnetic tape decreases.

When the magnetic recording medium 1 is a thin film type magnetic recording medium, the metal magnetic film 3 may be made of Fe, C
o, Ni and other metals, Co-Ni-based alloys, Co-Pt-based alloys, Co-Pt-Ni-based alloys, Fe-Co-based alloys, Fe
-Ni alloy, Fe-Co-Ni alloy, Fe-Ni-
B-based alloy, Fe-Co-B-based alloy, Fe-Co-Ni-
In-plane magnetization recording metal magnetic film made of B-based alloy or Co-C
An r-based alloy film can be used.

As a method for forming the metal magnetic film 3, a physical vapor deposition method (PVD) such as plating, sputtering, or vacuum vapor deposition can be used. The metal magnetic film 3 is formed as a continuous film. .

For example, the metal magnetic film 3 can be formed by using a continuous winding type vacuum evaporation apparatus as shown in FIG.

The continuous winding type vapor deposition apparatus 11 is configured for so-called oblique vapor deposition, and the inside thereof is, for example, about 10 ^-3.
In the vacuum chamber 12 in a vacuum state of about (Pa), the metal magnet is cooled to, for example, about −20 ° C. and opposed to the cooling can 13 rotating in the counterclockwise direction (direction of arrow A) in the figure. An evaporation source 14 for the film 3 is provided.

The evaporation source 14 is a container such as a crucible containing a ferromagnetic metal material such as Co.
(Ferromagnetic metal material) is heated with an electron beam 16 accelerated from an electron beam source 15 to heat the ferromagnetic metal material.
It is evaporated in the direction of arrow B in the figure from the supply roll 18 rotating in the counterclockwise direction in the figure and adheres to the non-magnetic support 2 running along the peripheral surface of the cooling can 13 (evaporation). ) To form the metal magnetic film 3. Then, the nonmagnetic support 2 on which the metal magnetic film 3 is formed
Is taken up by a take-up roll 19.

At this time, a deposition-preventing plate 20 is provided between the vapor deposition source 14 and the cooling can 13, and a shutter 21 is provided on the deposition-preventing plate 20 so that the position of the shutter 21 can be adjusted. Only vapor particles incident at an angle of. Thus, the metal magnetic film 3 is formed by the oblique deposition method.

Note that guide rollers 22 and 23 are disposed between the supply roll 18 and the cooling can 13 and between the cooling can 13 and the take-up roll 19, respectively. Cooling can 1
A predetermined tension is applied to the non-magnetic support 2 running from 3 to the take-up roll 19 so that the non-magnetic support 2 runs smoothly.

Further, during the deposition of the metal magnetic film 3, oxygen gas is supplied to the surface of the non-magnetic support 2 through an oxygen gas inlet (not shown). The improvement of the property and weather resistance is aimed at. In addition, in order to heat the evaporation source 14, in addition to the above-described heating means using an electron beam, known means such as a resistance heating means, a high-frequency heating means, and a laser heating means can be used.

When the metal magnetic film 3 is an in-plane magnetization recording metal magnetic film, Bi, S
A base layer of a low melting point non-magnetic material such as b, Pb, Sn, Ga, In, Ge, Si, Tl is formed in advance, and a metal magnetic material is deposited or sputtered from a vertical direction, and these are formed in the metal magnetic film 3. The in-plane isotropy may be secured by improving the coercivity by dispersing the low-melting non-magnetic material to eliminate the orientation.

Protective Film 4 The protective film 4 is provided on the metal magnetic film 3 to prevent abrasion of the metal magnetic film 3 and to provide sliding durability and to protect the metal magnetic film 3 from external moisture. Provided. Also,
As a material of the protective film 4, carbon can be suitably used. Alternatively, diamond-like carbon (DLC), carbon nitride, SiO ₂ or the like having high hardness may be used. The thickness of the carbon protective film is preferably 2 to 100 nm, more preferably 5 to 100 nm, so as to reduce the spacing loss and obtain the effect of preventing the metal magnetic film 4 from being worn. 30 nm.

The method of forming the protective film 4 is generally sputtering, but is not particularly limited, and a known thin film forming method such as an ion beam plating method or a CVD method can be used.

For example, when a carbon protective film is formed, the protective film 4 can be formed using a magnetron sputtering apparatus 30 as shown in FIG.

The outside of the magnetron sputtering apparatus 30 is covered with a chamber 31. After the pressure in the chamber 31 is reduced to about 10 ^-4 (Pa) by the vacuum pump 32, the exhaust speed is reduced by reducing the angle of the valve 33 to be discarded to the vacuum pump 32 side from the fully opened state to 10 degrees. Ar gas is introduced from the gas introduction pipe 34, and the degree of vacuum is set to about 0.8 Pa.

The magnetron sputtering apparatus 30 has a cooling can 35 which is cooled to about −40 ° C. and rotates in a counterclockwise direction (direction of arrow A) in FIG. A target 36 to be arranged is provided.

The target 36 is a material for the carbon protective film, and is supported by a backing plate 37 constituting a cathode electrode. On the back side of the backing plate 37, a magnet 38 for forming a magnetic field is provided.
Are arranged. This magnetron sputtering apparatus 30
When the carbon protective film is formed by the gas introduction pipe 34,
From the cooling can 35 as an anode and the backing plate 37 as a cathode.
A voltage of 000 (V) is applied so that a current of 1.4 A flows.

By the application of this voltage, Ar gas is turned into plasma, and the ions of the target 36 are repelled by the ionized ions colliding with the target 36.
At this time, a magnet 38 is provided on the back side of the backing plate 37, and a magnetic field is formed near the target 36.
Will be concentrated near.

The atoms ejected from the target 36 are fed in the direction of arrow B in the figure from the supply roll 39 rotating counterclockwise in the figure, and travel along the peripheral surface of the cooling can 35. 3 adheres on the nonmagnetic support 2 on which the film is formed, and a carbon protective film is formed. Then, the non-magnetic support 2 on which the carbon protective film is formed is taken up by a take-up roll 41.

Lubricant Layer 5 As a lubricant for forming the lubricant layer 5, a conventionally known material can be used. Specifically, for example, in a hydrocarbon material, a fatty acid having 10 to 22 carbon atoms and a fatty acid having 10 to 22 carbon atoms are used.
A typical example is a fatty acid ester comprising a 22 fatty acid and an alcohol having 2 to 26 carbon atoms. In addition, as the fluorine-containing material, a perfluoropolyether (PFPE) -based fluorine-containing polymer is representative. In addition, low molecular fluorine-based materials, or
Some hydrocarbon materials and the like can also be used.

The lubricant layer 5 can be formed by a conventionally known method such as a dipping method and a spin coating method.

Here, the amount of the lubricant to be applied is 0.5
-100 mg / m ² , preferably 1-100 mg / m ² .
More preferably, it is in the range of 20 mg / m ² .

In the lubricant layer 5, the distribution of the lubricant on the magnetic recording medium is analyzed, and the optimum amount of the lubricant is determined. The distribution state and the optimum abundance of the lubricant on the magnetic recording medium can be analyzed and specified by using the magnetic recording medium analysis method described below.

The analysis method of the magnetic recording medium used here is as follows.
A fine probe is brought into contact with the sample surface, that is, the lubricant layer 5 of the magnetic recording medium 1, and the lubricant layer 5 is separated when the probe is separated.
It measures the adhesive force generated between the probe and the probe. Then, the adhesive force is measured at a plurality of different positions on the sample surface, and the measured value is statistically processed to obtain a standard deviation.

Here, the adhesive force in the present invention is defined as a force acting between the lubricant layer and the probe obtained by a measuring device having a fine probe and a highly sensitive detector. For example,
Atomic Force Microscope
When measured by AFM), the abscissa indicates the adhesion force of the probe on the magnetic recording medium 1 in the height direction, and the ordinate indicates the force applied to the probe by the cantilever at each position. Are defined as values from D to E in the force curve shown in FIG. Then, the standard deviation of the adhesive force is obtained, and the value obtained by dividing the standard deviation by the average value of the adhesive force is defined as the standard deviation of the adhesive force in the present invention. Then, the measurement of the adhesive force is performed by, for example, using an AFM cantilever 51 disposed on the magnetic recording medium 1 as shown in FIG.
As shown in FIG. 6, the magnetic recording medium 1 is brought into contact with a lubricant layer formed on the surface. Thereafter, as shown in FIG. 7, the AFM cantilever 51 is separated from the lubricant layer, and the adhesive force generated between the lubricant layer and the AFM cantilever 51 is measured by AFM.

The method for measuring the adhesive force is not limited to the AFM, and any method can be used as long as the adhesive force can be measured with high accuracy.

The absolute value of the adhesive force obtained as described above changes depending on the presence or absence of the lubricant present on the magnetic recording medium 1. When the amount of the lubricant is large, the meniscus force to be formed becomes large. Strength increases. On the other hand, when no lubricant is present or when the amount of the lubricant is small, the meniscus force is reduced and the adhesion is also reduced. Therefore, the adhesive force differs depending on the amount of the lubricant in the magnetic recording medium. In addition, the distribution of the lubricant, that is, the degree of coating of the lubricant causes a difference in the variation in the adhesive force depending on the location.

The absolute value of the adhesive force is affected by the viscosity of the lubricant. Therefore, when the material of the lubricant is different, the absolute value of the adhesive force changes. Therefore, the distribution of the lubricant cannot be evaluated based on the absolute value of the adhesive force.

Further, since the adhesive force is affected by surface adsorbed water existing on the surface of the magnetic recording medium, the magnitude of the absolute value can be compared under the same material or under the same environment. For example, when the same sample is held in different humidity environments, the surface adsorbed water is adsorbed on the surface of the magnetic recording medium, so that the sample held in a high humidity environment shows a high adhesive force.

On the other hand, the variation in the adhesive force does not depend on the material of the lubricant, but only on the distribution state of the lubricant, that is, the degree of covering of the lubricant. Therefore, by evaluating the variation in the adhesive force, the distribution state of the lubricant and the degree of covering can be directly grasped regardless of the material of the lubricant. For example, when there are samples having different standard deviations, a sample showing a smaller value can be said to be a sample having a higher lubricant coverage.

Further, there is a correlation between the variation in the adhesive force and the initial friction coefficient of the magnetic recording medium, and the variation in the adhesive force is evaluated by evaluating the variation in the adhesive force regardless of the material of the lubricant used. An optimum amount of lubricant can be defined.

The magnetic recording medium which can be analyzed by the above-described magnetic recording medium analysis method includes a metal thin film on a non-magnetic support, a carbon protective film on the metal thin film, and a magnetic recording medium containing an organic lubricant. And a thin-film magnetic recording medium having a layer formed thereon. Specific examples thereof include a thin-film metal magnetic recording tape, a so-called vapor-deposited tape, a floppy (registered trademark) disk, and a hard disk. In this method of analyzing a magnetic recording medium, a slight difference in adhesion is detected to check for the presence of a lubricant.
It is preferable to use the same material.

Further, as other magnetic recording media which can be analyzed by the method for analyzing a magnetic recording medium, there are a coating type magnetic recording medium and the like. However, from the viewpoint of the uniformity of the surface material, this method of analyzing a magnetic recording medium is very effective when applied to a thin-film magnetic recording medium.

The surface roughness (Ra) of the measurement object, that is, the magnetic recording medium, is preferably 5 nm or less. This is to reduce the error of the adhesive force measurement and perform the adhesive force measurement with high accuracy. The adhesion can be measured even when the surface roughness of the magnetic recording medium is rougher than 5 nm. However, if the roughness of the surface of the magnetic recording medium is too large, the adhesion may not be measured with high accuracy. That is, in this magnetic recording medium analysis method, it is preferable to remove as little as possible a factor that may lead to a decrease in measurement accuracy such as the surface properties of the magnetic recording medium in order to detect a very small difference in adhesion. Therefore, the surface roughness (R
By setting a) to 5 nm or less, it is possible to measure the adhesive force with high accuracy.

Therefore, in this method of analyzing a magnetic recording medium, as described above, the adhesive force is measured by, for example, an AFM or the like, and the standard deviation of the adhesive force is calculated. Then, the variation in the adhesive force is evaluated based on the standard deviation of the adhesive force. A large standard deviation indicates that the adhesion varies widely, that is, that the lubricant is unevenly distributed. In this case, the meniscus force generated between the magnetic recording medium and a sliding member such as a magnetic head is suppressed to be small, and the coefficient of friction between the magnetic recording medium and the sliding member such as a magnetic head is reduced. On the other hand, a small standard deviation indicates that the dispersion of the adhesive force is small, that is, that the lubricant is uniformly distributed. In this case, the meniscus force between the magnetic recording medium and a sliding member such as a magnetic head increases, and the coefficient of friction between the magnetic recording medium and the sliding member such as a magnetic head increases. Therefore, by evaluating the standard deviation of the adhesive force, it is possible to grasp the distribution state of the lubricant on the magnetic recording medium. Further, by defining the standard deviation of the adhesive force, the difference between the magnetic recording medium and the magnetic head is determined. It is possible to control the friction coefficient between them.

The method of analyzing a magnetic recording medium may be performed in water. In the above-described method of analyzing a magnetic recording medium, the adhesive force is usually measured in the air. However, in this case, water adsorbed on the surface exists on the magnetic recording medium, and the water adsorbed on the surface causes an increase in the adhesive force, which may make it difficult to distinguish the adhesive force due to the lubricant. This tends to be particularly pronounced when the humidity of the atmosphere is high. In such a case, by performing the measurement of the adhesive force in water, the influence of the above-mentioned surface adsorbed water can be completely ignored, so that only a small amount of the lubricant can be detected with high accuracy. That is, by measuring the adhesive force in water, the adhesive force can be measured with higher accuracy, and the adhesive force can be measured with higher reliability. FIG. 9 is a schematic diagram showing a state of measuring the adhesive force in water. When measuring the adhesive force in water, as shown in FIG. 9, the magnetic recording medium 1 serving as a sample is placed in a container 54 filled with water 53 so that the lubricant 52 is located on the water surface side. Then, a fine probe of the adhesive force measuring device, for example, the AFM cantilever 51 is brought into contact with the surface of the magnetic recording medium 1 in water, that is, the surface of the lubricant layer, and further separated. By performing the above operations, the adhesive force can be measured in the same manner as when measuring in the atmosphere.

Then, the magnetic recording medium 1 to which the present invention is applied
Is characterized by being formed such that the standard deviation of the adhesive force between the lubricant layer and the probe analyzed by the method for analyzing a magnetic recording medium described above is 0.06 or more. When the standard deviation of the adhesive force described above is less than 0.06,
The meniscus force between the magnetic recording medium and a sliding member such as a magnetic head increases, and the coefficient of friction between the magnetic recording medium and a sliding member such as a magnetic head increases. As a result, the magnetic recording medium cannot obtain good slidability, and the durability of the magnetic recording medium also decreases.

Therefore, by setting the standard deviation of the adhesive force between the lubricant layer and the probe to 0.06 or more, an optimal amount of lubricant is formed on the magnetic recording medium, and The coefficient of friction with a sliding member such as a magnetic head is kept low. As a result, the slidability between the magnetic recording medium and the sliding member is improved, and the durability of the magnetic recording medium can be improved. Here, the standard deviation of the adhesive force between the lubricant layer and the probe can be appropriately set to a desired value by adjusting the concentration of the lubricant in the lubricant layer, that is, the application concentration of the lubricant.

In a magnetic recording medium used for AV applications requiring still durability or the like, that is, an AV using the so-called helical scan method, the magnetic head repeatedly slides in the same place. It is preferable to increase the amount of the lubricant present as much as possible without sticking. The environment in which the magnetic recording medium used for AV is used is not necessarily a constant temperature and humidity environment. For example, a video recorder or the like is expected to be used in various environments. Particularly in a high-humidity environment, adsorption of surface adsorbed water to the surface of the magnetic recording medium is expected, and the meniscus caused by the surface adsorbed water causes the magnetic recording medium to stick to the magnetic head, not only hindering the movement of the magnetic head, The magnetic recording medium or the deck itself may be damaged. Thus, in the case of a magnetic recording medium expected to be used in a high humidity environment, not only the surface abundance of the lubricant in the magnetic recording medium, but also the surface design of the magnetic recording medium in consideration of the surface adsorbed water, That is, it is necessary to set the surface abundance of the lubricant and the distribution state of the lubricant to optimal conditions.

Therefore, the magnetic recording medium according to the present invention is characterized in that the standard deviation of the adhesive force between the lubricant layer and the probe is 0.15 or less in the thin film type magnetic recording medium. . By forming a lubricant layer in the thin-film magnetic recording medium in which the standard deviation of the adhesive force between the lubricant layer and the probe is 0.15 or less, the thin-film magnetic recording medium is stable in a high humidity environment. It is a magnetic recording medium suitable for AV applications using the helical scan method, which can run in a suitable manner.

On the other hand, in a magnetic recording medium used for so-called data storage such as data storage and backup, the magnetic head does not repeatedly slide in the same place, and the magnetic recording medium is mainly driven by a shuttle. Therefore, a large amount of lubricant is not necessarily required. Conversely, it can be said that the amount of the lubricant present on the surface of the magnetic recording medium is preferably smaller than that of the magnetic recording medium for AV use, from the viewpoint of suppressing deposits on the magnetic head.

Therefore, the magnetic recording medium according to the present invention is characterized in that the standard deviation of the adhesive force between the lubricant layer and the probe is 0.15 to 0.35 in the thin film type magnetic recording medium. Things. In a thin-film magnetic recording medium, the standard deviation of the adhesive force between the lubricant layer and the probe is 0.15 to 0.3.
By forming the lubricant layer designated as No. 5, the thin-film magnetic recording medium can run stably and is a magnetic recording medium suitable for so-called data storage applications such as data storage and backup.

Although the present invention has been described in detail, the present invention is not limited to the above description, and can be appropriately modified without departing from the gist of the present invention.

[0091]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a thin-film magnetic recording medium to which the present invention is applied will be described.

[Experiment 1] In Experiment 1, sample tapes of Samples 1 to 12 and Samples 13 to 18 were prepared, and the following characteristic evaluation was performed. First, sample tapes of samples 1 to 12 and samples 13 to 18 were prepared as follows.

Sample 1 In sample 1, a Co metal magnetic film was formed on a non-magnetic support made of polyethylene terephthalate by a continuous take-up evaporator, and then formed on the metal magnetic film using a magnetron sputtering apparatus. Then, a carbon protective film was formed. Further, a back coat layer is formed on the surface of the non-magnetic support opposite to the surface on which the metal magnetic film 4 is formed, and finally, a lubricant layer is formed on the carbon protective film to form a magnetic recording medium. Produced.

Specifically, a magnetic recording medium was manufactured as follows.

First, a nonmagnetic support having a thickness of 7.0 μm was used.
Of polyethylene terephthalate film was prepared.

Next, the continuous winding type vapor deposition apparatus as shown in FIG. 2 was evacuated so that the inside thereof became a vacuum state of about 10 ⁻³ (Pa), and the above-mentioned nonmagnetic support was This was set in this vapor deposition apparatus. Then, a metal magnetic film made of Co was formed on one main surface 1a of the nonmagnetic support in the presence of a small amount of oxygen by a continuous vacuum oblique deposition method. The incident angle of vapor deposition is 90 to 45 degrees in the normal direction of the nonmagnetic support, and the traveling speed of the nonmagnetic support is 50 m / min.
It was manufactured by adjusting the intensity of the electron beam so that the thickness of the metal magnetic film became 180 nm.

Next, the pressure of the magnetron sputtering apparatus as shown in FIG. 3 was reduced to about 10 ⁻⁴ (Pa), and then Ar gas was introduced to about 0.8 Pa. Then, the non-magnetic support having the metal magnetic film formed thereon is set in this magnetron sputtering apparatus, and is run at a speed of 5 m / min on a cooling can cooled to −40 ° C. to form a film of about 8 nm on the metal magnetic film. A thick carbon protective film was formed.

Next, a back coating was prepared according to the following composition. <Back coating composition> 100 parts by weight of carbon black (# 50, manufactured by Asahi Corporation) 100 parts by weight of polyester polyurethane (N-2304, manufactured by Nippon Polyurethane Co., Ltd.) Solvent: 500 parts by weight of methyl ethyl ketone 500 parts by weight of toluene The back coating thus applied was applied to the surface of the nonmagnetic support opposite to the surface on which the metal magnetic film was formed, and dried to form a 0.5 μm thick back coat layer.

Next, after forming the back coat layer,
While the metal magnetic film was in contact with the roll heated to 0 ° C., it was run at a speed of 100 m / min.

Thereafter, a lubricant solution containing Z-dol (trade name, manufactured by Ausimont), which is a perfluoropolyether (hereinafter, referred to as PFPE) -based lubricant, was prepared on the carbon protective film. A lubricant layer was provided on the carbon protective film by top coating.

Here, the solvent for the lubricant solution is HFE-7200 (trade name, manufactured by 3M Company) which is a fluorine-based solvent.
And the concentration of the lubricant was 0.05% by weight.

[0102] The raw magnetic tape in which the metal magnetic film, the carbon protective film, the back coat layer and the lubricant layer were formed on the non-magnetic support in this manner was cut into a width of 8 mm to obtain a sample tape.

Sample 2 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.1% by weight.
A sample tape was prepared in the same manner as in Sample 1, except that

Sample 3 When preparing a lubricant solution, Z-
sample 1 except that diac (trade name, manufactured by Ausimont) was used and the concentration of the lubricant was 0.05% by weight.
A sample tape was produced in the same manner as described above.

Sample 4 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.1% by weight.
A sample tape was prepared in the same manner as in Sample 3, except that

Sample 5 When preparing a lubricant solution, AM was used as a PFPE-based lubricant.
A sample tape was prepared in the same manner as in Sample 1, except that -2001 (trade name, manufactured by Ausimont) was used, and the concentration of the lubricant was 0.05% by weight.

Sample 6 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.1% by weight.
A sample tape was prepared in the same manner as in Sample 5, except that

Sample 7 When preparing a lubricant solution, Z-
sample 1 (trade name, manufactured by Audimont Co.) except that the concentration of the lubricant was 0.05% by weight.
A sample tape was produced in the same manner as described above.

Sample 8 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.1% by weight.
A sample tape was produced in the same manner as in Sample 7, except that

Sample 9 A sample tape was prepared in the same manner as in Sample 1, except that heptyl stearate was used as the lubricant and the concentration of the lubricant was 0.05% by weight.

Sample 10 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.1% by weight.
A sample tape was prepared in the same manner as in Sample 9, except that

Sample 11 A sample tape was prepared in the same manner as in Sample 1, except that stearic acid was used as the lubricant and the concentration of the lubricant was 0.05% by weight.

Sample 12 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.1% by weight.
A sample tape was prepared in the same manner as in Sample 11, except that

Sample 13 When preparing a lubricant solution, Z-dol (trade name, manufactured by Ausimont) was used as a lubricant, and the lubricant concentration was adjusted to 0.1.
A sample tape was prepared in the same manner as in Sample 1, except that the content was 3% by weight.

Sample 14 When preparing a lubricant solution, Z-diac was used as a lubricant.
A sample tape was prepared in the same manner as in Sample 1 except that the lubricant concentration was 0.3% by weight (trade name, manufactured by Audimont Co., Ltd.).

Sample 15 When preparing a lubricant solution, AM-2001 was used as a lubricant.
A sample tape was prepared in the same manner as in Sample 1 except that the lubricant concentration was 0.3% by weight (trade name, manufactured by Audimont Co., Ltd.).

Sample 16 When preparing a lubricant solution, Z-deal was used as a lubricant.
A sample tape was prepared in the same manner as in Sample 1 except that the lubricant concentration was 0.3% by weight (trade name, manufactured by Audimont Co., Ltd.).

Sample 17 A sample tape was prepared in the same manner as in Sample 1, except that heptyl stearate was used as the lubricant and the concentration of the lubricant was 0.3% by weight.

Sample 18 When preparing the lubricant solution, except that stearic acid was used as the lubricant and the concentration of the lubricant was 0.3% by weight.
A sample tape was produced in the same manner as in Sample 1.

The following characteristics were evaluated for the sample tapes manufactured from Samples 1 to 12 and Samples 13 to 18.

<Characteristics Evaluation> Adhesion Measurement Adhesion was measured using an atomic force microscope SPM-9500 (trade name, manufactured by Shimadzu Corporation) and Force C for SPM-9500.
Using urve software, the measurement was carried out at normal temperature and normal humidity under the following conditions, and the average value was defined as the adhesive force.

Measuring range: 6 × 6 μm Resolution (number of samplings): 64 × 64 (4096 points) Here, the term “adhesive force” means that the horizontal axis indicates the moving distance of the probe on the sample tape in the height direction, The force applied to the probe by the cantilever is defined as a value from D to E in the force curve diagram 4 shown on the vertical axis.

Then, the standard deviation of the adhesive force was obtained, and the value obtained by dividing the standard deviation by the average value of the adhesive force was defined as the adhesive force standard deviation in this experiment. Table 1 shows the results.
Shown in

Measurement of Friction Coefficient The sample tape was run in a constant temperature bath at a temperature of 25 ° C. and a humidity of 50% RH, and the friction coefficient was measured using a sliding friction tester. did.
Table 1 shows the results.

FIG. 8 shows the relationship between the standard deviation of the adhesive force and the initial coefficient of friction. In FIG. 8, in order to more clearly show the relationship between the adhesive force standard deviation and the initial coefficient of friction, the number of samples was increased.

[0126]

[Table 1]

From Table 1, it can be seen that in Samples 1 to 12, the adhesive force standard deviation was 0.06 or more and the initial coefficient of friction was 0.1 in all of the sample tapes, regardless of the lubricant material. 25 or less.
Here, a large adhesion standard deviation indicates that the dispersion of the adhesion is large, that is, that the lubricant is unevenly distributed.
Therefore, in Sample 12 of Sample 1 in which the standard deviation of the adhesive force is 0.06 or more, the amount of the lubricant is not too large, and the meniscus force generated between the sample tape and the sliding member such as the guide pin is small. It was found that the coefficient of friction was also kept low because it was kept low.

On the other hand, in Samples 13 to 18, the adhesive standard deviation was 0.06 or less and the initial coefficient of friction was 0.7 or more in any of the sample tapes regardless of the lubricant material. And is higher. Here, a small adhesive force standard deviation means that the dispersion of the adhesive force is small, that is, that the lubricant is uniformly distributed.
Therefore, in Samples 13 to 18, since the amount of the lubricant was large, the meniscus force generated between the sample tape and the sliding member such as the guide pin increased, and as a result, the coefficient of friction was increased. . It is considered that this is caused by increasing the concentration of the lubricant.

Further, from FIG. 8, it can be confirmed that the coefficient of friction increases when the standard deviation is less than 0.06 regardless of the material of the lubricant. On the other hand, the standard deviation is 0.
When it is 06 or more, it can be confirmed that the friction coefficient is reduced. A correlation was found between the standard deviation of the adhesive force and the coefficient of friction, and it was found from the master curve of the measurement results in FIG. 8 that the conditions for suppressing the coefficient of friction could be set low irrespective of the material of the lubricant. .

[Experiment 2] In Experiment 2, sample tapes of Samples 19 to 32 were prepared, and the following characteristic evaluation was performed. First, sample 19 was prepared as follows.
In addition, a sample tape of Sample 25 was prepared.

Sample 19 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.01% by weight when preparing the lubricant solution.

Sample 20 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.03% by weight when preparing the lubricant solution.

Sample 21 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.05% by weight when preparing the lubricant solution.

Sample 22 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.07% by weight when preparing the lubricant solution.

Sample 23 When preparing the lubricant solution, the concentration of the lubricant was adjusted to 0.1% by weight.
A sample tape was prepared in the same manner as in Sample 1, except that

Sample 24 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.2% by weight.
A sample tape was prepared in the same manner as in Sample 1, except that

Sample 25 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.3% by weight.
A sample tape was prepared in the same manner as in Sample 1, except that

The characteristics of the sample tapes of Samples 19 to 25 produced as described above were evaluated as follows.

<Characteristics Evaluation> Adhesive force measurement Adhesive force was measured using a Micro ca as a cantilever.
using ntilever OMCL-RC800PB (Olympus), which was surface-treated with C ₁₈ H ₃₅ SiC ₁₃ solution prepared in anhydrous chloroform. And at room temperature,
The measurement was carried out at normal humidity under the following conditions, and the average value was defined as the adhesive force.

Measuring range: 6 × 6 μm Resolution (number of samplings): 64 × 64 (4096 points) Here, the adhesive force refers to the position of the probe on the sample tape in the height direction along the horizontal axis, and The force applied to the probe by the cantilever is defined as a value from D to E in the force curve diagram 4 shown on the vertical axis.

Then, the standard deviation of the adhesive force was obtained, and the value obtained by dividing the standard deviation by the average value of the adhesive force was defined as the standard deviation of the adhesive force in this experiment. Figure 1 shows the results.
0 is shown.

Further, sample tapes of Samples 26 to 32 were produced as follows.

Sample 26 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.01% by weight when preparing the lubricant solution.

Sample 27 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.03% by weight when preparing the lubricant solution.

Sample 28 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.05% by weight when preparing the lubricant solution.

Sample 29 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.1% by weight.
A sample tape was prepared in the same manner as in Sample 1, except that

Sample 30 When preparing the lubricant solution, the concentration of the lubricant was adjusted to 0.2% by weight.
A sample tape was prepared in the same manner as in Sample 1, except that

Sample 31 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.3% by weight.
A sample tape was prepared in the same manner as in Sample 1, except that

Sample 32 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.5% by weight.
A sample tape was prepared in the same manner as in Sample 1, except that

The sample tapes of Samples 26 to 32 produced as described above were evaluated for the following characteristics.

<Characteristics Evaluation> The absorbance of the lubricant layer in the sample tape for measuring absorbance was measured by FT-IR
(Fourier Transform Infrared Spectroscopy). The FT-IR reflection absorption spectrum is N
Haricot's SplitPea as accessory using MAGANA-IR550 from icolet
(Infrared light incident angle: 45 degrees). A non-lubricated metal tape was used as a background, and a specific peak due to the lubricant was measured. FIG. 11 shows the FT-IR spectrum of each sample tape.

FIG. 10 shows that the standard deviation of the adhesive force tends to decrease as the coating concentration of the lubricant Z-dol, that is, the surface abundance of Z-dol in the sample tape increases. Here, a decrease in the adhesive force standard deviation indicates that the variation in the adhesive force depending on the position on the sample tape is small, and indicates that the lubricant is more uniformly present on the sample tape.
That is, even in the extremely low concentration, that is, in the region where the amount of the lubricant is very small, a difference is observed in the statistically processed adhesion standard deviation. Further, by comparing the magnitude of the standard deviation, it is possible to evaluate the amount and distribution of the lubricant on the surface of the sample tape, and it is also possible to make a relative comparison between the sample tapes.

On the other hand, from FIG.
The peak observed near 0 cm ^-1 is absorption of CF stretching vibration caused by Z-dol which is a lubricant existing on the sample tape. The larger the area surrounded by the peak (hereinafter, referred to as the peak area), the larger the Z
This indicates that -dol is abundant on the surface of the sample tape. As is clear from FIG. 11, as the application concentration of the lubricant increases, the peak area increases, and the lubricant on the sample tape surface, that is, Zd
The amount of ol is increasing. However, when the lubricant concentration is 0.03% by weight or less, almost no peak is detected. In other words, this region is the FT-IR measurement limit, depending on the measurement conditions. Therefore, in a region where the lubricant concentration is high, that is, in a region where the amount of the lubricant present on the surface of the sample tape is large, the relative comparison between the sample tapes can be performed by using the FT-IR. It can be seen that it is difficult to detect the amount of the lubricant present on the surface of the sample tape in a region where the application concentration of the agent is extremely low, that is, in the region where the amount of the lubricant present on the surface of the sample tape is extremely small.

In addition to the FT-IR, XPS and ES
Although it is possible to measure the amount of the lubricant by elemental analysis such as CA, there are problems such as volatilization of the lubricant in a vacuum or a long time for the measurement. For this reason, the measurement of the amount of the lubricant by the elemental analysis is not suitable for a case where a general analysis is possible but a high-accuracy and short-time measurement such as production control is required.

Therefore, from these facts, the adhesive force measuring method using, for example, the AFM used in this experiment is not suitable for measuring and managing the amount of lubricant present on the surface of the sample tape from the viewpoint of accuracy and measurement time. It turns out that this is a very effective technique. [Experiment 3] In Experiment 3, samples 33 to 41 were used.
Was prepared, and the following property evaluation was performed. First, sample tapes of Samples 33 to 41 were produced as follows.

Sample 33 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant layer was not formed.

Sample 34 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.01% by weight when preparing the lubricant solution.

Sample 35 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.03% by weight when preparing the lubricant solution.

Sample 36 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.05% by weight when preparing the lubricant solution.

Sample 37 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.075% by weight when preparing the lubricant solution.

Sample 38 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.1% by weight.
A sample tape was prepared in the same manner as in Sample 1, except that

Sample 39 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.15% by weight when preparing the lubricant solution.

Sample 40 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.2% by weight.
A sample tape was prepared in the same manner as in Sample 1, except that

Sample 41 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.3% by weight.
A sample tape was prepared in the same manner as in Sample 1, except that

The sample tapes of Samples 33 to 41 manufactured as described above were evaluated for the following characteristics.

<Characteristic evaluation> Adhesion force measurement Adhesion force was measured using a Micro ca as a cantilever.
nilever OMCL-RC800PB (Olympus) was used. Then, the sample tape was placed in a container filled with water so that the lubricant was located on the water surface side, measured in water under the following conditions, and the average value was defined as the adhesive force.

Measuring range: 6 × 6 μm Resolution (number of samplings): 64 × 64 (4096 points) Here, the term “adhesive force” means that the moving distance in the height direction of the probe on the sample tape is plotted on the horizontal axis and each position is measured. The force applied to the probe by the cantilever is defined as a value from D to E in the force curve diagram 4 shown on the vertical axis.

Then, the standard deviation of the adhesive force was obtained, and the value obtained by dividing the standard deviation by the average value of the adhesive force was defined as the adhesive force standard deviation in this experiment. Figure 1 shows the results.
It is shown in FIG.

FIG. 12 shows that the average adhesive force tends to increase as the application concentration of Z-dol, which is a lubricant, that is, the amount of Z-dol present on the surface increases. Here, the increase in the average value of the adhesive force indicates that the coating of the lubricant on the sample tape is increasing. That is, even in the extremely low concentration, that is, in the region where the amount of the lubricant is very small, a difference is observed in the average adhesive force. Further, by comparing the average values of the adhesive forces, it is possible to evaluate the amount and distribution of the lubricant on the sample tape surface, and it is also possible to make a relative comparison between the sample tapes.

Therefore, the above results and the above-described FIG.
From the results of the above, the adhesive force measurement method in water using, for example, AFM used in this experiment is very effective in measuring and managing the amount of lubricant present on the sample tape surface from the viewpoint of accuracy and measurement time. It turns out that it is a technique.

[Experiment 4] In Experiment 4, sample tapes of Samples 42 to 73 were prepared, and the following characteristic evaluation was performed. First, the sample 42 was prepared as follows.
In addition, a sample tape of Sample 49 was manufactured.

Sample 42 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant layer was not formed.

Sample 43 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.01% by weight when preparing the lubricant solution.

Sample 44 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.03% by weight when preparing the lubricant solution.

Sample 45 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.05% by weight when preparing the lubricant solution.

Sample 46 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.07% by weight when preparing the lubricant solution.

Sample 47 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.1% by weight.
A sample tape was prepared in the same manner as in Sample 1, except that

Sample 48 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.3% by weight.
A sample tape was prepared in the same manner as in Sample 1, except that

Sample 49 In preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.5% by weight.
A sample tape was prepared in the same manner as in Sample 1, except that

The following properties were evaluated for the sample tapes of Samples 42 to 49 produced as described above.

Adhesion Measurement Adhesion was measured using an atomic force microscope (AFM) SPM-9.
500 (trade name, manufactured by Shimadzu Corporation) and SPM-9500
Force Curve software was used. In addition, Micro cantilever OMC as a cantilever
Using L-RC800PB (Olympus), which was surface-treated with C ₁₈ H ₃₅ SiC ₁₃ solution prepared in anhydrous chloroform. Then, at normal temperature, the humidity was controlled to each condition of 1% RH or less, 20% RH, 50% RH, and 80% RH, and measured under the following conditions, and the average value was defined as the adhesive force.

Measuring range: 6 × 6 μm Resolution (number of samplings): 64 × 64 (4096 points) Here, the term “adhesive force” means that the horizontal axis indicates the moving distance of the probe on the sample tape in the height direction, The force applied to the probe by the cantilever is defined as a value from D to E in the force curve diagram 4 shown on the vertical axis.

Then, the standard deviation of the adhesive force was obtained, and the value obtained by dividing the standard deviation by the average value of the adhesive force was defined as the standard deviation of the adhesive force in this experiment. FIG. 13 shows the amount of increase in the average value of the adhesive force at each humidity at this time. The change in the adhesive force is defined as the average value of the adhesive force at a predetermined humidity,
It is the value obtained by subtracting the average value of the adhesive force at% RH or less.

Measurement of Friction Coefficient The friction coefficient was measured in a thermostat at a temperature of 25 ° C. by adjusting the humidity to 1% RH or less, 20% RH, 50% RH, and 80% RH.
The sample tape was run under the control of each condition of H, and the test was performed using a sliding friction tester. Here, the friction coefficient of the 10th pass was defined as the initial friction coefficient, and the friction coefficient of the 300th pass was defined as the post-travel friction coefficient. FIG. 14 shows the amount of increase in the initial friction coefficient at each humidity at this time. FIG. 15 shows the amount of increase in the coefficient of friction after traveling at each humidity. The increase in the coefficient of friction refers to the coefficient of friction at a predetermined humidity of 1% RH
The friction coefficient below is subtracted.

FIG. 13 shows that when the coating concentration of Z-dol as a lubricant, that is, when the amount of Z-dol present on the surface of the sample tape is low and the coating concentration is low, the change in the adhesive force becomes larger in a higher humidity environment. I understand. this is,
This indicates that the smaller the amount of the lubricant present on the surface of the sample tape, the more the water tends to be adsorbed to the surface of the sample tape in a high humidity environment. This tendency is due to Z-do
1) As the coating concentration increases, ie, as the amount of lubricant present on the sample tape surface increases,
When the dol application concentration is 0.25% by weight or more, that is, when the adhesive force standard deviation is 0.15 or less, the amount of increase in the adhesive force average value is 2 nm or less. This result indicates that water does not easily adsorb to the surface of the sample tape in this region, which is considered to be because the surface of the sample tape is covered with the lubricant to some extent.

Further, from FIGS. 14 and 15, it can be seen from FIG. 14 that when the coating concentration of Z-dol, which is a lubricant, is low and the amount of Z-dol present on the surface of the sample tape is low, the higher the humidity, the higher the initial friction coefficient. It can be seen that the amount of increase in the coefficient of friction and the amount of increase in the coefficient of friction after traveling increase. This result corresponds to the increase in the average value of the adhesive force shown in FIG. 13 and is caused by the adsorption of the surface adsorbed water to the sample tape surface. That is, if the surface of the sample tape is not covered with the lubricant to some extent, the surface adsorbed water is adsorbed on the surface of the sample tape, and the surface adsorbed water causes an increase in the coefficient of friction.

Next, sample tapes of samples 50 to 73 were prepared as follows.

Sample 50 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.25% by weight when preparing the lubricant solution.

Sample 51 In preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.3% by weight.
A sample tape was prepared in the same manner as in Sample 1, except that

Sample 52 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.4% by weight.
A sample tape was prepared in the same manner as in Sample 1, except that

Sample 53 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.5% by weight.
A sample tape was prepared in the same manner as in Sample 1, except that

When preparing a lubricant solution for Sample 54 , Z-
A sample tape was prepared in the same manner as in Sample 1, except that diac (trade name, manufactured by Ausimont) was used and the concentration of the lubricant was 0.3% by weight.

Sample 55 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.4% by weight.
A sample tape was prepared in the same manner as in Sample 54, except that

Sample 56 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.5% by weight.
A sample tape was prepared in the same manner as in Sample 54, except that

Sample 57 When preparing a lubricant solution, AM was used as a PFPE-based lubricant.
-2001 (trade name, manufactured by Ausimont Co.), except that the concentration of the lubricant was 0.3% by weight.
A sample tape was produced in the same manner as described above.

Sample 58 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.4% by weight.
A sample tape was produced in the same manner as in Sample 57, except that

Sample 59 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.5% by weight.
A sample tape was produced in the same manner as in Sample 57, except that

When preparing a sample 60 lubricant solution, Z-
A sample tape was prepared in the same manner as in Sample 1 except that the concentration of the lubricant was 0.3% by weight using "deal" (trade name, manufactured by Audimont Co.).

Sample 61 In preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.5% by weight.
A sample tape was prepared in the same manner as in Sample 60, except that

Sample 62 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.01% by weight when preparing the lubricant solution.

Sample 63 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.03% by weight when preparing the lubricant solution.

Sample 64 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.05% by weight when preparing the lubricant solution.

Sample 65 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.1% by weight.
A sample tape was prepared in the same manner as in Sample 1, except that

When preparing a lubricant solution for Sample 66 , Z-
sample 1 except that diac (trade name, manufactured by Ausimont) was used and the concentration of the lubricant was 0.01% by weight.
A sample tape was produced in the same manner as described above.

Sample 67 A sample tape was prepared in the same manner as in Sample 66, except that the lubricant concentration was 0.05% by weight when preparing the lubricant solution.

Sample 68 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.1% by weight.
A sample tape was prepared in the same manner as in Sample 66, except that

Sample 69 When preparing a lubricant solution, AM was used as a PFPE-based lubricant.
A sample tape was prepared in the same manner as in Sample 1, except that -2001 (trade name, manufactured by Ausimont) was used and the concentration of the lubricant was set to 0.01% by weight.

Sample 70 A sample tape was prepared in the same manner as in Sample 69, except that the lubricant concentration was 0.05% by weight when preparing the lubricant solution.

Sample 71 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.1% by weight.
A sample tape was prepared in the same manner as in Sample 69, except that

When preparing a sample 72 lubricant solution, Z-
sample 1 (trade name, manufactured by Audimont Co.) except that the concentration of the lubricant was 0.05% by weight.
A sample tape was produced in the same manner as described above.

Sample 73 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.1% by weight.
A sample tape was prepared in the same manner as in Sample 72, except that

The characteristics of the sample tapes of Samples 50 to 73 produced as described above were evaluated in the same manner as described above, and the standard deviation of the adhesive force, the increase in the average value of the adhesive force, the increase in the initial friction coefficient, and the friction after running were measured. The coefficient increase was determined. The results are shown in Tables 2 and 3. Each increase is obtained by subtracting the value at 1% RH or less from the value at 80% RH.

[0213]

[Table 2]

[0214]

[Table 3]

From Table 2, it is found that Samples 50 to 61
It can be seen that, regardless of the type of the lubricant, the standard deviation of any adhesive force is 0.15 or less, and the increase in the average adhesive force is 2 nN or less. This indicates that a sample tape having an adhesive force standard deviation of 0.15 or less is less likely to have surface adsorbed water on the surface of the sample tape even when the sample tape is held in a high humidity environment. Therefore, when the adhesive force standard deviation is 0.
In Samples 50 to 61 of 15 or less, the initial friction coefficient increase amount and the post-running friction coefficient increase amount fell to low values, and the sample tape was stable even in a high-humidity environment as in a low-humidity environment. It can be said that traveling is possible.

On the other hand, from Table 3, the standard deviation of the adhesive force was 0.1
In samples 62 to 73 exceeding 5 or more, the increase in the average value of the adhesive force is 3 nN or more regardless of the type of the lubricant. The increase in the adhesive force average value is more remarkable as the value of the adhesive force standard deviation is larger. This result indicates that the lower the coverage of the lubricant on the sample tape surface, the more easily the surface adsorbed water is adsorbed on the sample tape surface. Therefore, sample 6
In samples 2 to 73, the initial friction coefficient increase amount and the post-running friction coefficient increase amount are large, and it can be seen that these increases are involved in the adsorption of surface adsorbed water.

From the above results, the standard deviation of the adhesive force was 0.1.
The magnetic tape on which the lubricant layer having a thickness of 5 or less is formed suppresses the adsorption of surface adsorbed water to the surface of the magnetic tape under a high humidity environment, and as a result, a stable running even in a high humidity environment. It can be said that it becomes possible.

[Experiment 5] In Experiment 5, sample tapes of Samples 74 to 97 were prepared, and the following characteristics were evaluated. First, a sample 74 was prepared as follows.
In addition, a sample tape of Sample 97 was prepared.

Sample 74 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.05% by weight when preparing the lubricant solution.

Sample 75 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.1% by weight.
A sample tape was prepared in the same manner as in Sample 1, except that

Sample 76 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.15% by weight when preparing the lubricant solution.

When preparing a sample 77 lubricant solution, the concentration of the lubricant was adjusted to 0.2% by weight.
A sample tape was prepared in the same manner as in Sample 1, except that

Sample 78 When preparing a lubricant solution, Z-
A sample tape was prepared in the same manner as in Sample 1, except that diac (trade name, manufactured by Ausimont) was used and the concentration of the lubricant was 0.1% by weight.

Sample 79 In preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.2% by weight.
A sample tape was produced in the same manner as in Sample 78, except that

Sample 80 A sample tape was prepared in the same manner as in Sample 78, except that the lubricant concentration was 0.25% by weight when preparing the lubricant solution.

Sample 81 In preparing a lubricant solution, AM was used as a PFPE-based lubricant.
A sample tape was prepared in the same manner as in Sample 1, except that -2001 (trade name, manufactured by Ausimont) was used, and the concentration of the lubricant was 0.05% by weight.

Sample 82 In preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.1% by weight.
A sample tape was prepared in the same manner as in Sample 81, except that

Sample 83 A sample tape was prepared in the same manner as in Sample 81, except that the lubricant concentration was 0.15% by weight when preparing the lubricant solution.

When preparing a lubricant solution for Sample 84 , Z-
sample 1 (trade name, manufactured by Audimont Co.) except that the concentration of the lubricant was 0.05% by weight.
A sample tape was produced in the same manner as described above.

Sample 85 In preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.1% by weight.
A sample tape was produced in the same manner as in Sample 84, except that

Sample 86 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.01% by weight when preparing the lubricant solution.

Sample 87 A sample tape was prepared in the same manner as in Sample 1, except that the lubricant concentration was 0.03% by weight when preparing the lubricant solution.

Sample 88 When preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.3% by weight.
A sample tape was prepared in the same manner as in Sample 1, except that

Sample 89 In preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.5% by weight.
A sample tape was prepared in the same manner as in Sample 1, except that

When preparing a sample 90 lubricant solution, Z-
sample 1 except that diac (trade name, manufactured by Ausimont) was used and the concentration of the lubricant was 0.01% by weight.
A sample tape was produced in the same manner as described above.

Sample 91 A sample tape was prepared in the same manner as in Sample 90, except that the lubricant concentration was 0.03% by weight when preparing the lubricant solution.

Sample 92 In preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.4% by weight.
A sample tape was prepared in the same manner as in Sample 90, except that

Sample 93 When preparing a lubricant solution, AM was used as a PFPE-based lubricant.
A sample tape was prepared in the same manner as in Sample 1, except that -2001 (trade name, manufactured by Ausimont) was used and the concentration of the lubricant was set to 0.01% by weight.

Sample 94 A sample tape was prepared in the same manner as in Sample 93, except that the lubricant concentration was 0.03% by weight when preparing the lubricant solution.

Sample 95 In preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.3% by weight.
A sample tape was prepared in the same manner as in Sample 93, except that

Sample 96 When preparing a lubricant solution, Z-
sample 1 (except for Ausimont Co., Ltd.) and the concentration of the lubricant was 0.03% by weight.
A sample tape was produced in the same manner as described above.

Sample 97 In preparing a lubricant solution, the concentration of the lubricant was adjusted to 0.3% by weight.
A sample tape was prepared in the same manner as in Sample 96, except that

The following characteristics were evaluated for the sample tapes of Samples 74 to 97 manufactured as described above.

Adhesion Measurement Adhesion was measured by using an atomic force microscope (AFM) SPM-9.
500 (trade name, manufactured by Shimadzu Corporation) and SPM-9500
Force Curve software was used. In addition, Micro cantilever OMC as a cantilever
Using L-RC800PB (Olympus), which was surface-treated with C ₁₈ H ₃₅ SiC ₁₃ solution prepared in anhydrous chloroform. And it measured on condition of the following at normal temperature and normal humidity, and made the average value the adhesive force.

Measuring range: 6 × 6 μm Resolution (number of samplings): 64 × 64 (4096 points) Here, the term “adhesive force” means that the moving distance in the height direction of the probe on the sample tape is plotted on the horizontal axis. The force applied to the probe by the cantilever at the position is defined as a value from D to E in the force curve diagram 4 shown on the vertical axis.

Then, the standard deviation of the adhesive force was obtained, and the value obtained by dividing the standard deviation by the average value of the adhesive force was defined as the adhesive force standard deviation in this experiment.

Measurement of Friction Coefficient The friction coefficient was measured by running a sample tape in a thermostat controlled at a temperature of 25 ° C. and a humidity of 25% RH.
This was performed using a sliding friction tester. Here, the friction coefficient of the 10th pass was defined as the initial friction coefficient, and the friction coefficient of the 300th pass was defined as the post-travel friction coefficient.

Measurement of Friction Coefficient Error Rate Measurement Method The error rate is measured by measuring a sample tape in a thermostat controlled at a temperature of 25 ° C. and a humidity of 25% RH. Deck: SDX-S500C (trade name, manufactured by Sony Corporation) The test was run by using Specifically, after a predetermined signal was first recorded on the sample tape, the error rate was measured while repeatedly reading only for 5 seconds. Then, the number of runs until the error rate became 1 × 10 ⁻² or more, that is, the number of readings was measured. Reading was performed up to 20,000 times, and under this measurement condition, those with 10,000 passes or less were unsuitable.

The above results are shown in Tables 4 and 5.

[0250]

[Table 4]

[0251]

[Table 5]

As shown in Table 4, Samples 74 to 85
Does not depend on the type of the lubricant, the standard deviation of any adhesive force is in the range of 0.15 to 0.35, and no problem is recognized in the initial friction coefficient, the friction coefficient after running, and the error rate.
It is considered that this is because the adhesion standard deviation of the lubricant on the sample tape surface shows an appropriate adhesion distribution of 0.15 to 0.35, that is, the lubricant distribution.

On the other hand, Sample 86, Sample 87, Sample 90, Sample 91, Sample 93, Sample 94
And the sample standard 96 has an adhesive force standard deviation of 0.35
The sample having a value exceeding the above has a large coefficient of friction after running.
This is because a sample having an adhesive force standard deviation larger than 0.35 is not sufficiently lubricated because the lubricant is scattered on the surface of the sample tape, that is, the lubricant is very little. It is considered that Samples having an adhesive force standard deviation of less than 0.15, such as Sample 88, Sample 89, Sample 92, Sample 95, and Sample 97, have too much lubricant on the surface of the sample tape, and thus have a large amount of lubricant. A deposit may have occurred, and a good error rate has not been obtained.

From the above results, there is an appropriate range for the standard deviation of the adhesive force of the lubricant on the tape surface in a magnetic tape used for so-called data storage such as data storage and backup. It can be said that only good running durability can be obtained. That is, it can be said that the magnetic tape on which the lubricant layer having the adhesive force standard deviation of 0.15 to 0.35 is formed can obtain good running durability.

[0255]

As described in detail above, the magnetic recording medium according to the present invention has at least a metal magnetic film formed on one main surface of a non-magnetic support and the above-described metal magnetic film is formed. In a magnetic recording medium having a lubricant layer on the outermost layer of one main surface on the other side, the standard deviation of the adhesive force between the lubricant and the probe is 0.06 or more.

In the magnetic recording medium according to the present invention, since the standard deviation of the adhesive force between the lubricant and the probe is 0.06 or more, the amount of the lubricant present on the surface of the magnetic recording medium is reduced. It is set to an optimum amount for maintaining good properties and durability.

Therefore, according to the present invention, it is possible to provide a magnetic recording medium having a low coefficient of friction, excellent running properties and durability.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram schematically illustrating a configuration example of a magnetic recording medium according to the present invention.

FIG. 2 is a schematic configuration diagram of a continuous winding type vapor deposition apparatus.

FIG. 3 is a schematic configuration diagram of a magnetron sputtering apparatus.

FIG. 4 is a schematic diagram of a force curve in measurement by an atomic force microscope.

FIG. 5 is a view for explaining a method for measuring an adhesive force,
FIG. 3 is a diagram showing a state in which a cantilever is arranged on a magnetic recording medium.

FIG. 6 is a diagram for explaining a method of measuring an adhesive force, and shows AFM.
FIG. 4 is a diagram showing a state in which the cantilever is brought into contact with a lubricant layer on the surface of the magnetic recording medium.

FIG. 7 is a view for explaining a method of measuring an adhesive force,
FIG. 4 is a diagram illustrating a state in which the cantilever is separated from above the magnetic recording medium.

FIG. 8 is a characteristic diagram showing a relationship between an adhesion standard deviation and an initial friction coefficient.

FIG. 9 is a diagram showing a state of measuring an adhesive force in water.

FIG. 10 is a characteristic diagram showing a relationship between a Z-dol coating concentration and an adhesive force standard deviation.

FIG. 11 is a characteristic diagram showing the relationship between the wave number and the absorbance of each sample tape.

FIG. 12 is a characteristic diagram showing a relationship between a Z-dol application concentration and an average adhesive force.

FIG. 13 is a characteristic diagram showing a relationship between a Z-dol coating concentration and an increase in an average value of an adhesive force.

FIG. 14 is a characteristic diagram showing a relationship between a Z-dol application concentration and an increase amount of an initial friction coefficient.

FIG. 15 is a characteristic diagram showing a relationship between a Z-dol application concentration and an increase amount of a friction coefficient after running.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Magnetic recording medium, 2 Non-magnetic support, 3 Metal magnetic film, 4 Protective film, 5 Lubricant layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takahiro Kamei 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Takeshi Takeshi 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Hiroshi Iwamoto 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Toshinori Tsuboi 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Inside the corporation

Claims (5)

[Claims] 1. A magnetic recording system comprising: a metal magnetic film formed on at least one main surface of a nonmagnetic support; and a lubricant layer on an outermost layer on one main surface on which the metal magnetic film is formed. In the medium, the standard deviation of the adhesive force between the lubricant layer and the probe is 0.0
6. A magnetic recording medium, wherein the number is 6 or more. 2. The magnetic recording medium according to claim 1, wherein said magnetic recording medium is a coating type magnetic recording medium. 3. The magnetic recording medium according to claim 1, wherein said magnetic recording medium is a thin-film magnetic recording medium. 4. A magnetic recording medium for AV using a helical scan method, wherein a standard deviation of an adhesive force between the lubricant layer and the probe is 0.06 or more and 0.15 or less. The magnetic recording medium according to claim 3, wherein 5. A magnetic recording medium for data storage, wherein a standard deviation of an adhesive force between the lubricant layer and the probe is 0.15 or more and 0.35 or less. The magnetic recording medium according to the above.