JP2001229529A - Method for quantitative analysis of surface lubricant on magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out accurate, easy and rapid quantitative analysis of a surface lubricant on the surface of a magnetic recording medium. SOLUTION: The lubricant 105 on the surface of a magnetic recording medium 100 is quantitatively analyzed. Then the lubricant 105 is removed from the surface of the magnetic recording medium after the quantitative analysis of the lubricant so as to prepare a reference sample. The surface of the reference sample is quantitatively analyzed. Both analyses are compared to each other to determine the quantity of the lubricant on the surface of the magnetic recording medium 100.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an attenuated total reflection Fourier transform infrared spectrometer (hereinafter simply referred to as ATR-F) provided with an attenuated total reflection prism (hereinafter simply referred to as ATR prism).
T-IR) for quantitative analysis of lubricant on the surface of a magnetic recording medium.

[0002]

2. Description of the Related Art Conventionally, as a magnetic recording medium, a ferromagnetic powder such as a magnetic metal oxide powder or a magnetic alloy powder has been used.
A magnetic layer composed of a binder such as a vinyl chloride-vinyl acetate copolymer, a polyester resin, a urethane resin and a polyurethane, and an organic solvent is coated on a non-magnetic support to form a magnetic layer. So-called coating type magnetic recording media are widely used.

On the other hand, as the demand for high-density recording has increased, there has been proposed a metal magnetic thin film type magnetic recording medium capable of obtaining high saturation magnetization since a magnetic layer does not contain a non-magnetic binder. In a magnetic recording medium of a metal magnetic thin film type, for example, Co, Co—Ni alloy, Co—Cr alloy, and Co—
A metal magnetic material such as O is applied to a non-magnetic support such as a polyethylene terephthalate film, a polyethylene naphthalate film and an aramid film by plating or vacuum thin film forming technology (vacuum deposition, sputtering, ion plating, etc.). When used, the magnetic layer is formed by direct deposition.

The metal magnetic thin film type magnetic recording medium has various advantages as compared with the coating type magnetic recording medium. For example, it is excellent in magnetic characteristics such as coercive force and squareness ratio, and electromagnetic conversion characteristics in a short wavelength region. Further, since the thickness of the magnetic layer can be made extremely thin, the thickness loss during recording demagnetization and reproduction is significantly reduced.
Further, since it is not necessary to mix a binder, which is a non-magnetic material, in the magnetic layer, it is possible to increase the filling degree of the magnetic material in the magnetic layer.

[0005] In the magnetic recording medium of the metal magnetic thin film type as described above, in order to further improve the electromagnetic conversion characteristics and form a magnetic layer capable of obtaining a larger output, a metal magnetic material is formed on a nonmagnetic support. Has been proposed. The magnetic recording medium of the metal magnetic thin film type obliquely deposited with a metal magnetic material has less recording demagnetization and is easy to record with a ring head due to the structure of the magnetic layer, so it is used for 8 mm video tape recorders and digital video cassettes. It has been put to practical use as a magnetic recording medium.

However, in a metal thin film type magnetic recording medium formed by the oblique evaporation method, the surface of the magnetic layer becomes close to a mirror surface, and tends to stick to the magnetic head. Therefore, by providing minute projections on the surface of the non-magnetic support so that the projections are present on the surface of the magnetic layer, the substantial contact area between the surface of the magnetic layer and the magnetic head is reduced. Innovative measures have been taken to ensure durability.

[0007] In a digital video tape recorder, the data transfer rate is increased along with the high recording density. The relative speed between the magnetic head and the surface of the magnetic recording medium in digital recording is twice as fast as that in analog recording. Further, a magnetic recording medium for business use is required to have specifications capable of coping with severe use conditions such as an edit mode. As described above, in the magnetic recording medium used in the field where the magnetic head rotates at high speed, the surface of the magnetic layer of the magnetic recording medium is greatly damaged, and further improvement in running durability, still durability and the like is required. . Therefore,
Techniques for forming a protective film such as carbon on the surface of a magnetic layer have been studied.

Further, in a magnetic recording medium of the metal magnetic thin film type, a lubricant is applied to the surface of the magnetic layer or the surface of the protective film to reduce the friction coefficient generated between the magnetic head and the surface of the magnetic recording medium, thereby reducing the magnetic field. Attempts have been made to prevent the magnetic recording medium from sticking to the head and to improve the running properties and durability of the magnetic recording medium.

[0009]

The amount of the lubricant to be applied to the surface of the magnetic recording medium greatly affects the durability of the magnetic recording medium, and therefore needs to be controlled with high precision. Conventionally, there has been proposed a method of measuring a quantitative analysis of a lubricant using an attenuated total reflection Fourier infrared spectrometer. In this case, a method using a lubricant-uncoated portion of the same lot as a magnetic recording medium sample as a reference sample is proposed. Suggested.

However, in one magnetic recording medium of one lot, the lubricant-applied portion and the lubricant-unapplied portion are:
Since parts that are separated in the manufacturing process of the magnetic recording medium and are no longer necessary as products are discarded, it is often difficult to obtain a lubricant-uncoated part in a subsequent inspection stage.

In the case where a lubricant-uncoated portion is obtained and used as a reference sample, the thickness of the magnetic layer of the lubricant-uncoated portion is determined by comparing the thickness of the magnetic recording medium coated with the lubricant to be compared. The thickness of the magnetic layer at the measurement point may be significantly different from that of the magnetic layer, which causes a decrease in measurement accuracy. Therefore, development of a new measurement method has been desired.

The present invention has been proposed based on the conventional situation, and proposes an accurate, easy, and quick method for quantitatively analyzing the lubricant on the surface of a magnetic recording medium.

[0013]

According to the present invention, there is provided a method for quantitatively analyzing a surface lubricant of a magnetic recording medium, comprising: a hemispherical attenuated total reflection prism having a smooth flat bottom surface; A metal element to be in close contact with the bottom surface, comprising a contact pressure control device for finely adjusting the contact pressure between the sample surface and the bottom surface of the attenuated total reflection prism, between the metal indenter and the magnetic recording medium sample A step of performing quantitative analysis of the lubricant on the surface of the magnetic recording medium when measuring the quantitative analysis of the lubricant by an attenuated total reflection Fourier transform infrared spectrometer provided with a cushioning material; and Removing a lubricant from the surface of the recording medium to produce a reference sample and performing a quantitative analysis of the surface of the reference sample.

In the method for quantitatively analyzing the surface lubricant of a magnetic recording medium according to the present invention, it is not necessary to obtain a lubricant-coated portion and a lubricant-uncoated portion of a magnetic recording medium of the same lot at an inspection stage. Since the reference sample from which the surface lubricant of the magnetic recording medium has been removed is prepared in the step, the inspection step of the magnetic recording medium after the manufacturing process is simplified.

In a conventional inspection method in which a lubricant-uncoated portion is obtained and used as a reference sample, a lubricant in which the thickness of the magnetic layer in the lubricant-uncoated portion is compared is applied. Although the thickness of the magnetic layer may be significantly different from the thickness of the magnetic layer at the measurement point of the magnetic recording medium, the measurement accuracy may be reduced. Since a reference sample with the surface lubricant removed has been prepared, a decrease in measurement accuracy is avoided, and accurate, easy, and rapid quantitative analysis of lubricant on the surface of a magnetic recording medium is performed. .

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The method for quantitatively analyzing the surface lubricant of a magnetic recording medium according to the present invention comprises a hemispherical attenuated total reflection prism (abbreviated as a hemispherical ATR prism) having a flat bottom surface and a sample. A metal element for bringing the surface into close contact with the bottom surface of the hemispherical ATR prism; a contact pressure control device for finely adjusting the contact pressure between the sample surface and the bottom surface of the hemispherical ATR prism; During the measurement of the quantitative analysis of the lubricant by an attenuated total reflection Fourier transform infrared spectrometer equipped with a cushioning material, during the quantitative analysis of the lubricant on the surface of the magnetic recording medium, after the quantitative analysis Removing a lubricant from the surface of the magnetic recording medium to produce a reference sample, and performing a quantitative analysis of the surface of the reference sample.

Hereinafter, the method for quantitatively analyzing the surface lubricant of a magnetic recording medium according to the present invention will be described by way of an example, but the method of the present invention is not limited to the following examples.

In the method of the present invention, as a magnetic recording medium applied for quantitative analysis of a lubricant, a magnetic metal material is deposited on a non-magnetic support to form a metal magnetic thin film type magnetic layer. The metal magnetic thin film type magnetic layer is formed by depositing a magnetic metal material on a non-magnetic support and a metal magnetic thin film type magnetic recording medium having an organic lubricant applied on the magnetic layer. A protective film such as a diamond-like carbon film is formed on the magnetic layer, and any of magnetic metal thin film type magnetic recording media in which an organic lubricant is provided on the protective film can be applied.

Therefore, in the following example, a quantitative analysis of the lubricant on the surface of the magnetic recording medium is performed by using a long magnetic tape-shaped metal magnetic thin film type magnetic recording medium such as a digital video cassette as a sample for measurement. The case of performing the operation will be described.

FIG. 1 is a schematic sectional view showing an example of a magnetic recording medium 100 applied in the method of the present invention.

The magnetic recording medium 100 shown in FIG. 1 has a nonmagnetic support 101 made of, for example, a polyethylene terephthalate film, a magnetic layer 102, a protective film 103 made of, for example, diamond-like carbon, and a lubricant layer 10
5 is formed.

The magnetic layer 102 is formed by depositing a metallic magnetic material on the non-magnetic support 101, and has a composition of, for example, CoXNi (100-X) (where X = 100-80 and X is Weight% of each element
(Represented by the following). FIG.
1 shows a schematic cross-sectional view of an example of a vacuum evaporation apparatus 11 used for forming a magnetic layer 102 of a long magnetic recording medium 100. The inside of this vacuum evaporation apparatus 11 is about 10 ^-3 [P
a) in the vacuum chamber 12 in a vacuum state of about
A cooling can 13 cooled to about ° C. and rotating in a counterclockwise direction (the direction of arrow A in FIG. 2), and a vapor deposition source 1 arranged to face the cooling can 13 for forming a metal magnetic thin film
4.

The vapor deposition source 14 is one in which a metal magnetic material such as Co is accommodated in a container such as a crucible. This evaporation source 1
4, the electron beam generator 15 accelerates and irradiates an electron beam 16 to heat the evaporation source 14, thereby evaporating the metal magnetic material. Then, the cooling can 1 is fed out from the supply roll 17 rotating in the counterclockwise direction in the direction of arrow B in the drawing.
A metal magnetic thin film, that is, a magnetic layer 102 is formed by depositing a metal magnetic material on the non-magnetic support 23 running along the peripheral surface of No. 3. After the metal magnetic thin film is formed, it is taken up on a take-up roll 18.

At this time, a deposition-preventing plate 19 is provided between the evaporation source 14 and the cooling can 13, a shutter 20 whose position can be adjusted is provided on the deposition-preventing plate 19, and a predetermined angle with respect to the nonmagnetic support 23. In this case, the metal magnetic material is deposited obliquely on the non-magnetic support by allowing only the vapor deposition particles incident thereon to pass therethrough. Such an evaporation method is called an oblique evaporation method.

It should be noted that guide rolls 21 and 22 are disposed between the supply roll 17 and the cooling can 13 and between the cooling can 13 and the take-up roll 18, respectively.
A predetermined tension is applied to the non-magnetic support 23 running from the supply roll 17 to the cooling can 13 and from the cooling can 13 to the take-up roll 18 so that the non-magnetic support 23 runs smoothly.

Further, at the time of depositing such a metal magnetic thin film, oxygen gas is supplied to the surface of the nonmagnetic support 23 through an oxygen gas inlet (not shown), whereby the metal magnetic thin film, The magnetic properties, durability and weather resistance of the layer 102 are improved. In addition, in order to heat the evaporation source 14, in addition to the heating means using the electron beam 16 as described above, for example, a conventionally known method such as a resistance heating means, a high-frequency heating means, and a laser heating means may be appropriately used. it can. As a method for forming a metal magnetic thin film using a metal magnetic material, a conventionally known thin film forming method such as a vertical evaporation method or a sputtering method can be appropriately used in addition to the oblique evaporation method. Further, as the metal magnetic material, C
Magnetic metals such as o, Ni, and Fe, and alloys thereof can be used alone or in combination.

However, in order to improve the adhesion strength between the non-magnetic support member 23 and the metal magnetic material, or to improve the durability of the metal magnetic thin film itself such as weather resistance and abrasion resistance, the atmosphere at the time of vapor deposition is as follows: It is desirable to use a metal magnetic thin film obtained when the atmosphere contains oxygen gas. Further, the thickness of the metal magnetic thin film is preferably about 0.01 to 0.2 [μm], and most preferably about 0.1 to 0.2 [μm].

The protective film 103 shown in FIG.
2 made of, for example, diamond-like carbon having relatively high hardness. By forming this protective film 103, abrasion of the magnetic layer 102 can be effectively avoided when the magnetic recording medium is run.

FIG. 3 shows the magnetic recording medium 100 shown in FIG.
FIG. 1 shows a schematic configuration diagram of an example of a magnetron sputtering apparatus 30 for forming a protective film 103 constituting the same. The magnetron sputtering apparatus 30 shown in FIG.
The outside of the chamber 31 is covered by
A cooling can 35 cooled to about −40 ° C. and rotated in a counterclockwise direction (the direction of arrow A in the figure).
And a target 3 disposed opposite to the cooling can 35
6 are arranged.

The chamber 31 has a vacuum pump 32
After the pressure is reduced to about 10 ⁻⁴ [Pa], the angle of the valve 33 that exhausts air to the vacuum pump 32 side is
The exhaust speed is reduced by narrowing down 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 target 36 is a carbon protective film 103
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.

The magnetron sputtering apparatus 30 shown in FIG.
When forming the carbon protective film 103, Ar gas is introduced from the gas introduction pipe 34, and a voltage of about 3000 [V] is applied using the cooling can 35 as an anode and the backing plate 37 as a cathode. 1.4
The state where the current [A] flows is maintained. By the application of this voltage, Ar gas is turned into plasma and ionized A
When the r ions collide with the target 36, the atoms of the target 36 are repelled. At this time, a magnetic field is formed near the target 36 by the magnet 38 provided on the back side of the backing plate 37, so that the ionized ions are concentrated near the target 36.

Nonmagnetic support 2 on which magnetic metal thin film is formed
5 is fed in the direction of arrow B from the supply roll 39 rotating counterclockwise, and travels along the peripheral surface of the cooling can 35. Then, the atoms ejected from the target 36 adhere to the metal magnetic thin film, whereby the carbon protective film 103 is formed. The non-magnetic support on which the carbon protective film 103 is formed is taken up by a take-up roll 40.

The thickness of the carbon protective film 103 is 3 to 3 so as to be effective for reducing the spacing loss of the magnetic recording medium 100 and for preventing the metal magnetic thin film from being worn.
It is desirable to set it to about 15 [nm],
It is preferable to set it to about 10 [nm].

In the above description, an example in which the carbon protective film 103 is formed using the magnetron sputtering apparatus 30 has been described. Any conventionally known thin film forming method such as a beam plating method and a CVD method can be similarly applied.

Next, the lubricant layer 105 shown in FIG. 1 will be described. The lubricant layer 105 is formed on the magnetic recording medium 10.
The coating is applied on the protective film 103 or the magnetic layer 102 in order to improve the running property due to the shape of the fine projections on the surface of the zero. In this example, a lubricant layer 105 made of, for example, perfluoropolyether is formed on the protective film 103 in the magnetic recording medium of FIG.

The lubricant used to form the lubricant layer 105 includes silicone oil, fluoroalcohol, polyolefins such as polyethylene wax, polyglycols such as polyethylene oxide wax, alkyl phosphates, polyphenyl ether, and C10 carbon atoms. ~ 2
0 monobasic fatty acids and a monohydric or dihydric alcohol having 3 to 12 carbon atoms, a trihydric alcohol,
Fatty acid esters comprising one or more of a tetrahydric alcohol and a hexahydric alcohol, having 1 carbon atom
Fatty acid esters composed of a monohydric fatty acid and a mono- to hexahydric alcohol having 11 to 28 carbon atoms by adding 0 or more monobasic fatty acids and the carbon number of the fatty acid can be used. Also,
Fatty acids having 8 to 22 carbon atoms, fatty acid amides, and fatty acid alcohols can also be used.

Specific examples of these organic compound lubricants include butyl caprylate, octyl caprylate, ethyl laurate, octyl laurate, ethyl myristate, butyl myristate, octyl myristate, ethyl palmitate, and palmitate. Butyl, octyl palmitate, ethyl stearate, butyl stearate, octyl stearate, amyl stearate, anhydrosorbitan monostearate, anhydrosorbitan distearate, anhydrosorbitan tristearate, anhydrosorbitan tetrastearate, Oleyl oleate, oleyl alcohol, lauryl alcohol and the like.

Further, the front and back surfaces of the magnetic recording medium 100 shown in FIG. 1, or the vicinity thereof, or the carbon protective film 103, a void in the metal magnetic thin film, ie, the magnetic layer 102, the interface between the carbon protective film 103 and the magnetic layer 102. Various additives such as a rust inhibitor, an antistatic agent, and a fungicide may be added to the interface between the magnetic layer 102 and the non-magnetic support 101, the non-magnetic support 101, and the like, if necessary, using conventionally known means. It is possible to add.

Next, the back coat layer 104 constituting the magnetic recording medium 100 shown in FIG. 1 will be described. The back coat layer 104 is formed on the non-magnetic support 101 and on the non-magnetic support 101 opposite to the surface on which the magnetic layer 102 is formed. Is what you do. This back coat layer 104
Comprises a binder, carbon black, and an inorganic powder.

Examples of the binder contained in the back coat layer 104 include a thermoplastic resin, a thermosetting resin, a reactive resin, and a mixture thereof. Examples of the thermoplastic resin include vinyl chloride, vinyl acetate, vinyl alcohol, maleic acid, acrylic acid, acrylate, styrene, butadiene, ethylene, vinyl butyral, vinyl acetal, and a polymer containing vinyl ether as a structural unit, or Copolymers can be mentioned. As the copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylate-acrylonitrile copolymer, acrylate-vinylidene chloride copolymer Acrylate-styrene copolymer, methacrylate-acrylonitrile copolymer, methacrylate-vinylidene chloride copolymer, methacrylate-styrene copolymer, vinylidene chloride-acrylonitrile copolymer, butadiene −
An acrylonitrile copolymer, a styrene-butadiene copolymer, a chlorovinyl ether-acrylate copolymer, and the like can be given.

In addition to the above polymers, polyamide resins, cellulose resins such as cellulose acetate butyrate, cellulose diacetate, cellulose propionate, nitrocellulose, polyvinyl fluoride, polyester resins, polyurethane resins, and various rubber resins Resins can also be applied.

Examples of the thermosetting resin or the reactive resin include a phenol resin, an epoxy resin, a polyurethane curing resin, a urea resin, a melamine resin, an alkyd resin, an acrylic reaction resin, a formaldehyde resin, a silicone resin,
Epoxy-polyamide resins, mixtures of polyester resins and polyisocyanate prepolymers, mixtures of polyester polyols and polyisocyanates, and the like are also included.

On the other hand, the binder has improved dispersibility and durability.
In order to achieve this, -COOM, -SO
_ThreeM, -OSO_ThreeM, -P = (OM)_Two, -OP = O
(OM) _Two(M is a hydrogen atom or an alkali metal base
Represent. ), -OH, -NR_Two, -NR_Three(R is hydrocarbon
Represents a group. ), Epoxy group, -SH, -CN, etc.
At least one polar group is copolymerized or added
It is preferably introduced by a reaction. Such a polar group is
10^-1-10^-8[Mol / g]
And preferably 10^-2-10^-6Guided by [mol / g]
More preferably, it is inserted.

The binder contained in the back coat layer 104 is 5 parts by weight with respect to 100 parts by weight of non-magnetic powder (all non-magnetic powder components such as carbon black, which will be described later).
It is preferably used in the range of 100 to 100 parts by weight, and more preferably in the range of 10 to 80 parts by weight.

A polyisocyanate for crosslinking and curing the binder contained in the back coat layer 104 can be used in combination. As the polyisocyanate, tolylene diisocyanate, 4-4 ^'- diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, naphthylene-1,
Examples thereof include isocyanates such as 5-diisocyanate, o-toluidine diisocyanate, isophorone diisocyanate, and triphenylmethane triisocyanate, products of these isocyanates and polyalcohols, and polyisocyanates formed by condensation of isocyanates. .

The carbon black contained in the back coat layer 104 has an average particle size of 10 to 20 μm.
m], or coarse carbon black having an average particle size of 230 to 300 [μm].

When the particulate carbon black is added to the back coat layer 104, the surface electric resistance and the light transmittance of the back coat layer 104 can be set low. Many magnetic recording devices use the light transmittance of a tape and use it as a signal for a recording operation. In such a case, the addition of fine carbon black is effective. Further, since the particulate carbon black has excellent holding power to a lubricant, it is possible to reduce the coefficient of friction of a back tension post or the like in a magnetic recording / reproducing apparatus by using a lubricant together with a back coat layer.

Specific examples of the particulate carbon black include RAVEN2000B (18 nm) and RAVEN
1500B (17 nm) (all manufactured by Columbia Carbon), BP800 (17 nm) (Cabot), P
RINTEX90 (14 nm), PRINTEX95
(15 nm), PRINTEX85 (16 nm), PR
INTEX75 (17 nm) (all manufactured by Degussa), #
3950 (16 nm) (manufactured by Mitsubishi Chemical Corporation) and the like.

On the other hand, when the coarse-grained carbon black is added to the back coat layer 104, fine projections are formed on the surface of the back coat layer 104. With these small protrusions,
In the magnetic recording / reproducing apparatus, the contact area between the back coat layer 104 and the back tension post or the like can be reduced, and the friction coefficient can be reduced. That is, the coarse carbon black has a function as a solid lubricant.

Specific examples of the coarse-grained carbon black include thermal black (270 nm) (manufactured by Kahn Calp) and RAVEN MTP (275 nm) (manufactured by Columbia Carbon).

It is particularly preferable to use two or more types of carbon black having different average particle sizes for the back coat layer 104. When two or more types of carbon blacks having different average particle sizes are used in the back coat layer 104, the content ratio (weight ratio) between the fine particle carbon black and the coarse particle carbon black is determined as follows: fine particle carbon black: coarse particle carbon Black = 98: 2 to 75:25 is preferred, 95: 5 to 85: 1
More preferably, it is in the range of 5.

The total content of carbon black in the back coat layer 104 is usually preferably 30 to 80 parts by weight, and more preferably 45 to 65 parts by weight, based on 100 parts by weight of the binder. Is more preferable.

Examples of the inorganic powder contained in the back coat layer 104 include α-iron oxide, α-alumina, and chromium oxide (Cr ₂ O ₃ ). These inorganic powders may be used alone or in combination of two or more.
In particular, α-iron oxide or α-alumina is preferable as the inorganic powder. The inorganic powder contained in the back coat layer 104 preferably has a Mohs hardness of 5 to 9. The average particle size of the inorganic powder contained in the back coat layer 104 is preferably 80 to 250 [nm], and more preferably 100 to 210 [nm].

It is also possible to use calcium carbonate in combination with the above inorganic powder. The average particle size of the calcium carbonate is preferably from 80 to 250 [nm], and more preferably from 100 to 210 [nm].

By using an inorganic powder having a Mohs hardness of 5 to 9, the running durability of the magnetic recording medium 100 can be imparted, and the back coat layer 104 can be strengthened. In addition, when the inorganic powder is used for the back coat layer 104 together with carbon black and calcium carbonate, the back coat layer 104 is less deteriorated even by repeated sliding due to a filler effect, and becomes strong.

Further, by using an inorganic powder having a Moh's hardness of 5 to 9, an appropriate polishing force is generated on the surface of the back coat layer 104, and adhesion to a guide pole or the like is reduced. Further, when the inorganic powder and calcium carbonate are used in combination, the sliding characteristics with respect to a guide pole having a rough surface are improved, and the friction coefficient of the back coat layer 104 can be stabilized.

The content of the inorganic powder is preferably 3 to 30 parts by weight, more preferably 3 to 20 parts by weight, based on 100 parts by weight of carbon black.

It is preferable to add a dispersant to the back coat layer 104 in order to disperse the carbon black and the non-magnetic powder contained in the back coat layer 104 well in the binder. Examples of the dispersant to be contained in the back coat layer 104 include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, and stearolic acid. , Etc. having 12 or more carbon atoms
18 fatty acids (RCOOH, R is an alkyl group or alkenyl group having 11 to 17 carbon atoms), a metal soap of an alkali metal or an alkaline earth metal of the fatty acid, a fluorine-containing compound of the fatty acid ester, Amides of the above fatty acids, polyalkylene oxide alkyl phosphates, lecithin, trialkyl polyolefinoxy quaternary ammonium salts (alkyl has 1 to 1 carbon atoms)
5, olefins such as ethylene and propylene), sulfates, and copper phthalocyanine. These may be used alone or in combination. In particular, it is preferable to use a combination of copper oleate, copper phthalocyanine, and barium sulfate as a dispersant in the back coat layer.

The dispersant contained in the back coat layer 104 is 0.5 to 20 parts by weight based on 100 parts by weight of the binder resin contained in the back coat layer 104.
It is preferable to add in the range of. The back coat layer 104 may further contain, as necessary, conductive particles other than carbon black, a dustproofing agent, and the like as a plasticizer and an antistatic agent.

Further, the back coat layer 104 can contain a lubricant. As the lubricant contained in the back coat layer 104, a fatty acid or a fatty acid ester can be used.

As fatty acids, acetic acid, propionic acid, octanoic acid, 2-ethylhexanoic acid, lauric acid, myristic acid, stearic acid, palmitic acid, behenic acid, arachinic acid, oleic acid, linoleic acid, linolenic acid, elaidic acid And aliphatic carboxylic acids such as palmitoleic acid or mixtures of these aliphatic carboxylic acids.

The fatty acid esters include butyl stearate, sec-butyl stearate, isopropyl stearate, butyl oleate, amyl stearate,
-Methylbutyl stearate, 2-ethylhexyl stearate, 2-hexyldecyl stearate, butyl palmitate, 2-ethylhexyl myristate, a mixture of butyl stearate and butyl palmitate, oleyl oleate, butoxyethyl stearate, 2- Butoxy-1-propyl stearate, dipropylene glycol monobutyl ether acylated with stearic acid, diethylene glycol dipalmitate, hexamethylene diol acylated with myristic acid to form a diol, and esters such as oleate of glycerin Compounds can be mentioned. These fatty acid esters may be used alone or in combination.

As the lubricant to be contained in the back coat layer 104, the binder 1 contained in the back coat layer 104
It is preferable to add 1 to 5 parts by weight to 00 parts by weight.

The magnetic recording medium 100 having the above configuration
The method of quantitatively analyzing the lubricant on the surface of the magnetic recording medium will be described below with reference to examples.

First, FIG. 4 shows a schematic configuration diagram of a single beam measuring device 110 of an attenuated total reflection Fourier transform infrared spectrometer (hereinafter simply referred to as an ATR-FT-IR device). The single beam measuring device 110 includes an interference light source unit 41, a measuring unit 50, and a signal processing unit 60. The interference light source unit 41 includes an infrared light source 42, a movable mirror 43, and a half mirror 44. In the measuring section 50, the hemispherical ATR prism 51
, An incident angle varying device 55 and a detector 56 are provided in a sample chamber (not shown). Signal processing unit 60
, A signal amplifier 61 and a Fourier transformer 62
, A memory 63, and a display unit 64, which are connected in order.

The inside of the sample chamber of the measuring section 50 is shown in FIG.
The schematic configuration is shown in FIG. The sample chamber includes a hemispherical ATR prism 51, a contact pressure control device 52, and a buffer 53. The hemispherical ATR prism 51 is a hemispherical prism made of germanium or silicon and having a flat bottom surface. The contact pressure control device 52 includes a metal indenter, a pressing mechanism for bringing the metal indenter into close contact with the surface of the sample 54, a pressure detecting mechanism for detecting a contact pressure between the surface of the sample 54 and the hemispherical ATR prism 51, And a control mechanism for appropriately moving the metal indenter by the pressing mechanism based on data detected by the detection mechanism to control the contact pressure within a predetermined range. Specifically, a metal indenter is brought into close contact with the surface of the sample 54 by a spring or a hydraulic mechanism, and the above-mentioned adhesion pressure is sensed by a sensor such as a metal indenter connected to a control mechanism. When it is out of the range, the hydraulic mechanism is operated by the control mechanism to move the metal indenter appropriately.

As the sample 54 to be measured, two types, a sample and a reference, are prepared. In this example of the measuring method of the present invention, a metal thin film type magnetic recording medium in which a lubricant layer 105 is formed on a magnetic layer 102, such as the magnetic recording medium 100 shown in FIG. 1, is used as a sample. On the other hand, as a reference, the lubricant layer 105 was removed from the sample, and the lubricant layer 1 was removed.
05 shall not be used. This reference is obtained by removing the lubricant layer 105 from the sample. In this removal, for example, a wiping cloth or a wiping paper can be used, but the wiping cloth or the wiping paper is impregnated with a solvent. The lubricant layer 1 from the sample surface
05 can be removed, or the lubricant layer 105 can be removed from the sample surface by ultrasonic cleaning of the measured sample in a solvent.

As the solvent used in the method of wiping the lubricant with a wiping cloth or wiping paper impregnated with a solvent to remove the lubricant layer 105, there are water and various organic solvents which are liquid at room temperature. For example, as hydrocarbons, pentane, isopentane, hexane, isohexane, methylpentane, heptane, isoheptane, octane, isooctane, isooctene, nonane, decane,
Dodecane, dodecene, cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, phenylcyclohexane, bicyclohexyl, benzene, toluene, xylene, amylbenzene, diamylbenzene, amyltoluene, diphenylethane, tetralin,
Examples include decalin, ethylbenzene, diethylbenzene, triethylbenzene, cumene, secondary butylbenzene, cymen, turpentine, dipentene, and the like.

Examples of the halogenated hydrocarbons include methylene chloride, chloroform, bromoform, ethylidene chloride,
Trichloroethane, trichloroethylene, perchlorethylene, bromochloroethane, isopropyl chloride, trichloropropane, dichlorobutane, hexachloropropylene, hexachlorobutadiene, amyl chloride, dichloropentane, chlorobenzene, chlorotoluene, dichlorotoluene and the like. .

As alcohols, methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, secondary butyl alcohol, tertiary butyl alcohol,
Amyl alcohol, isoamyl alcohol, secondary amyl alcohol, tertiary amyl alcohol, hexyl alcohol, methyl amyl alcohol, ethyl butyl alcohol, heptyl alcohol, octyl alcohol, secondary octyl alcohol, ethylhexyl alcohol, isooctyl alcohol, nonyl alcohol, benzyl alcohol And the like.

Examples of the ethers include ethyl ether, isopropyl ether, ethyl butyl ether, butyl ether, amyl ether, hexyl ether, methyl cellosolve, cellosolve, diethyl cellosolve, tetrahydrofuran and the like.

Examples of ketones include acetone, methyl acetone, methyl ethyl ketone, methyl propyl ketone, diethyl ketone, methyl butyl ketone, methyl isobutyl ketone, ethyl butyl ketone, butyrone, methyl amyl ketone, methyl hexyl ketone, valerone, diacetone alcohol and the like. Is mentioned.

As a method of removing the lubricant layer 105 by ultrasonic cleaning, for example, a sample to which a lubricant is applied is placed in a beaker of about 100 [ml] for about 50 [ml]. The beaker is placed in an ultrasonic cleaner of about 40 [kHz] filled with water and filled with water, and ultrasonic cleaning is performed for about 1 [minute] to wash away the lubricant.

The magnetic recording medium 100 shown in FIG.
A protective film 103 is provided on the magnetic layer 102.
3 has a configuration in which a lubricant layer 105 is formed thereon. In the measurement method of the present invention, in addition to this example, the present invention is applied to any metal thin-film magnetic recording medium having a conventionally known configuration. be able to.

When measuring the infrared absorption spectrum for quantitative analysis of the lubricant on the surface of the magnetic recording medium,
The surface to be analyzed of the sample 54 is brought into close contact with the bottom surface of the hemispherical ATR prism 51 with an appropriate pressure using the contact pressure control device 52. The surface to be analyzed of the sample 54 in the method of the present invention is defined as the magnetic layer 10 constituting the magnetic recording medium.
It is assumed that the surface is on the formation side.

Further, it is assumed that a cushioning material 53 is sandwiched between the sample and the metal indenter constituting the contact pressure control device 52. The material of the cushioning member 53 is preferably an elastic rubber because it can sufficiently absorb impact.
Specific examples of the material of the buffer material 53 include silicone rubber, neoprene rubber, natural rubber, chloroprene rubber, butadiene styrene rubber, butyl rubber, urethane rubber, and the like. Further, as a material of the cushioning material, a cork material, Japanese paper, cloth, or the like can be applied. When elastic rubber is used as the cushioning material 53, it is preferable to use a thin sheet having a thickness of about 2 [mm] or less.

The pressure at which the sample 54 is brought into close contact with the hemispherical ATR prism 51 is 2 [kgf / cm ² ].
It is desirable that: When the sample 54 is brought into close contact with the hemispherical ATR prism 51 at a pressure higher than 2 [kgf / cm ² ], when the metal thin-film type magnetic recording medium is used as the sample 54, the sample 54 may be broken. Because there is. Further, when a plurality of samples are analyzed as a sample and a reference to be compared, and the analysis results are compared with each other, the contact pressure control device 52 causes the contact pressure Pr of the reference sample to the hemispherical ATR prism 51 to change. And the contact pressure P for a sample sample
It is desirable to adjust s and the same value as much as possible. By increasing the accuracy of the identity of the measurement conditions of the sample to be compared, the accuracy of the analysis of the infrared absorption spectrum is improved. The absolute value of the difference between Pr and Ps is 0.05
[Kgf / cm ² ] or less is desirable to increase the measurement accuracy.

The operation of analyzing the infrared absorption spectrum of the measurement sample and the reference sample to be compared will be described with reference to FIG. First, infrared light from the infrared light source 42 (wave number range is, for example, 400 cm ^{-1 to} 500
0 cm ^-1 ) to the hemispherical ATR prism 51
(For example, θ = 45 °), the reflected light from the sample is detected by the detector 56, and then processed by the signal amplifier 61 and the Fourier transformer 62 of the signal processing unit 60 to obtain an infrared absorption spectrum. . Then, the result of the infrared absorption spectrum is recorded in the memory 63 and also displayed on the display unit 64.

The measurement operation as described above is performed for each of a plurality of measurement samples and reference samples.
Then, the analysis result of the sample and the analysis result of the reference are compared with each other, and the result of the quantitative analysis of the sample is obtained. As a result, accurate, easy, and quick analysis results can be obtained.

Next, an embodiment of the method for quantitatively analyzing the surface lubricant of the magnetic recording medium of the present invention will be described. However, the method of the present invention is not limited to the following examples.

(Example) First, a magnetic layer is formed on a non-magnetic support made of, for example, a polyethylene terephthalate film under the following evaporation conditions. Next, in the magnetic layer,
A carbon protective film is formed by a magnetron sputtering device. For sputtering, carbon was used as a target, and the pressure was 0.5 [Pa] from a gas introduction pipe.
, An argon gas is introduced, and the power is 6.8 [W / c].
m ² ]. [Evaporation conditions] Metallic magnetic material: Co Incident angle: 45 ° Magnetic layer thickness: 0.2 [μm] Evaporation rate: 25 [m / min]

Further, on the non-magnetic support, on the surface on the non-magnetic support opposite to the surface on which the magnetic layer is formed, a back coat layer mainly composed of carbon is formed to a thickness of 0.5 [μm]. To form a coating. Next, as the lubricant, a plurality of lubricants in which the content of perfluoroether in the solvent was changed from 0.1 [% by weight] to 0.6 [% by weight] were prepared. These lubricants were applied on the carbon protective film to prepare a plurality of sample samples of the magnetic recording medium.

Next, a reference sample to be compared with the sample sample is prepared. The sample prepared as described above is analyzed by an infrared absorption spectrum, and then the lubricant layer is removed to obtain a reference sample. Specifically, it can be manufactured by applying ethyl alcohol as an organic solvent, soaking it into a wiping paper, and wiping and removing a lubricant.

For each of the sample sample and the reference sample prepared as described above, the infrared absorption spectrum of a lubricant, for example, a perfluoropolyether molecule was measured by a single beam measuring device 110 shown in FIG. When performing this measurement, the cushioning material 53
For example, a sheet-like elastic rubber material having a thickness of, for example, about 1 [mm] is sandwiched between a sample 54 and a metal indenter (not shown) constituting the contact pressure control device 52. Then, the quantitative analysis of the lubricant on the surface of the magnetic recording medium of the sample sample was performed using the area value of the CF bond stretching vibration peak in the perfluoropolyether molecule.

FIG. 6 shows an example of the infrared absorption spectrum of the perfluoropolyether molecule of the lubricant of the sample sample obtained by the single beam measuring device. According to the infrared absorption spectrum shown in FIG. 6, three peaks appear roughly. That is, the first peak 7
1 is a stretching vibration peak of a CH bond, a second peak 72 is a stretching vibration peak of a CO bond, and a third peak 73 is a CF bonding stretching vibration peak.

Similarly, when the infrared absorption spectrum of the reference sample is measured by the single beam measuring apparatus, the infrared absorption spectrum shown in FIG. 6 cannot be obtained because the lubricant has been removed from the reference sample. . Therefore, the amount of the lubricant on the surface of the magnetic recording medium can be accurately and easily determined by comparing the infrared absorption spectra of the two.

Further, the quantitative analysis of the lubricant on the surface of the magnetic recording medium was also performed by XPS. And the above ATR-F
The results of the quantitative analysis of the lubricant on the surface of the magnetic recording medium by T-IR and the results of the quantitative analysis of the lubricant on the surface of the magnetic recording medium by XPS were compared.

As a method of quantitatively analyzing a lubricant on the surface of a magnetic recording medium by XPS, for example, when perfluoropolyether generally used as a lubricant for a magnetic recording medium is used, this perfluoropolyether is used. 700 to 680 [eV] corresponding to the binding energy of the carbon-fluorine bond in the 1s orbit of fluorine contained in the polyether molecule.
In the range, the spectrum was captured, and the integrated value [cps] of the spectrum (hereinafter simply referred to as [cps] below (count / sec)) was taken as the quantitative analysis result.

FIG. 7 shows the result of quantitative analysis of the lubricant on the surface of the magnetic recording medium by XPS. As shown in FIG. 7, the quantitative analysis result of the lubricant on the magnetic recording medium surface by ATR-FT-IR and the quantitative analysis result of the lubricant on the magnetic recording medium surface by XPS have a good correlation. .

In the above-described embodiment, as a method for removing the lubricant from the sample sample of the magnetic recording medium, a method of applying ethyl alcohol as an organic solvent, soaking it into a wiping paper, and wiping the lubricant is applied. However, the present invention is not limited to this example. That is, various organic solvents suitable for removing the lubricant can be similarly applied, and even when the method for removing the lubricant by the ultrasonic cleaning method is applied, similar to the above-described embodiment, Thus, the effect that the quantitative measurement of the lubricant can be performed simply, reliably and quickly can be obtained.

[0092]

According to the method for quantitatively analyzing the surface lubricant of a magnetic recording medium according to the present invention, it is necessary to obtain a lubricant-coated portion and a lubricant-uncoated portion of a magnetic recording medium of the same lot in an inspection stage. Since the reference sample in which the surface lubricant of the magnetic recording medium was removed at the inspection stage was prepared, the quantitative measurement step of the lubricant on the surface of the magnetic recording medium performed after the manufacturing process was simplified.

In the inspection stage after the manufacture of the magnetic recording medium, a lubricant-uncoated portion of the same lot is obtained and used as a reference sample in the conventional inspection method. The thickness of the layer may be different from the thickness of the magnetic layer at the measurement location of the magnetic recording medium coated with the lubricant to be compared, which has led to a decrease in measurement accuracy. In the quantitative analysis method of the agent, in the measurement step of the surface lubricant of the magnetic recording medium, from the magnetic recording medium sample sample after measurement of the surface lubricant of the magnetic recording medium, to produce a reference sample from which the lubricant was removed, Since the measurement results of the two are compared, the measurement conditions of the two can be equalized, and thereby the accurate, easy, and quick lubrication of the surface of the magnetic recording medium can be achieved. I was able to perform a quantitative analysis of the agent.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an example of a magnetic recording medium applied in a method for quantitatively analyzing a lubricant on the surface of a magnetic recording medium according to the present invention.

FIG. 2 shows a schematic configuration diagram of an example of a vacuum evaporation apparatus for forming a magnetic layer.

FIG. 3 shows a schematic configuration diagram of an example of a magnetron sputtering apparatus for forming a carbon protective film.

FIG. 4 is a schematic configuration diagram of an example of a single beam measuring device used in the method for quantitatively analyzing a lubricant on the surface of a magnetic recording medium according to the present invention.

FIG. 5 is a schematic configuration diagram illustrating the inside of a measurement unit included in the single beam measurement device.

FIG. 6 shows an example of an infrared absorption spectrum of a perfluoropolyether molecule of a lubricant of a sample sample obtained by a single beam measurement device.

FIG. 7 shows the results of quantitative analysis of lubricant on the surface of a magnetic recording medium by XPS.

[Explanation of symbols]

Reference Signs List 11 vacuum evaporation apparatus, 12 vacuum chamber, 13 cooling can, 14 evaporation source, 15 electron beam generation source, 16 electron beam, 17 supply roll, 18 take-up roll, 1
9 non-magnetic support, 20 shutter, 21 and 22 guide rolls, 23 non-magnetic support, 25 non-magnetic support on which metal magnetic thin film is formed, 30 magnetron sputtering apparatus,
31 chamber, 32 vacuum pump, 33 valve,
34 gas inlet pipe, 35 cooling can, 36 target, 37 backing plate, 38 magnet, 3
9 supply roll, 40 take-up roll, 41 interference light source unit, 42 infrared light source, 43 movable mirror, 44 half mirror, 50 measuring unit, 51 hemispherical ATR prism, 52 contact pressure control device, 53 buffer material, 54 sample,
55 variable incident angle device, 60 signal processing unit, 61 signal amplifier, 62 Fourier transformer, 63 memory, 64
Display unit, 100 magnetic recording medium, 101 non-magnetic support, 102 magnetic layer, 103 protective film, 104 back coat layer, 105 lubricant layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) C10M 105/38 C10M 105/38 105/74 105/74 107/02 107/02 107/34 107/34 107 / 38 107/38 C10N 40:18 C10N 40:18 (72) Inventor Noriyuki Kishi 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Takahiro Kamei Kita-Shinagawa, Shinagawa-ku, Tokyo 6-7-35 Inside Sony Corporation (72) Kenichi Kurihara, the inventor 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo 7-35 Inside Sony Corporation (72) Ken, Kobayashi 6-chome Kita-Shinagawa, Shinagawa-ku, Tokyo No. 7-35 Sony Corporation F term (reference) 4H104 BB03A BB08A BB17A BB32A BB34A BE11A BH03A CA01A CB14A CD04A CJ02A PA16 5D112 AA07 BC01 JJ06

Claims (5)

[Claims] 1. A hemispherical attenuated total reflection prism having a smooth flat bottom surface, and a metal indenter for bringing a sample surface into close contact with the bottom surface of the attenuated total reflection prism. A contact pressure control device for finely adjusting the contact pressure with the bottom surface, between the metal indenter and the magnetic recording medium sample, by an attenuated total reflection Fourier transform infrared spectrometer provided with a buffer material,
When performing quantitative analysis of the lubricant on the surface of the magnetic recording medium, performing a quantitative analysis of the lubricant on the surface of the magnetic recording medium; and removing the lubricant from the surface of the magnetic recording medium after the quantitative analysis. A method for quantitatively analyzing a surface lubricant of a magnetic recording medium, comprising: a step of preparing a reference sample by performing the method; and a step of performing quantitative analysis of the surface of the reference sample. 2. The step of removing a lubricant from the surface of the magnetic recording medium to produce a reference sample, wherein the lubricant is removed from the surface of the magnetic recording medium using an organic solvent. A method for quantitatively analyzing a surface lubricant of a magnetic recording medium according to claim 1. 3. The step of removing a lubricant from the surface of the magnetic recording medium to produce a reference sample, wherein the lubricant is removed from the surface of the magnetic recording medium by ultrasonic cleaning. A method for quantitatively analyzing a surface lubricant of a magnetic recording medium according to claim 1. 4. A contact pressure control device, comprising: a metal indenter, a pressing mechanism for bringing the metal indenter into close contact with the sample surface, a pressure detecting mechanism for detecting a contact pressure between the sample surface and the attenuated total reflection prism, 2. The surface of a magnetic recording medium according to claim 1, further comprising: a control mechanism for controlling a contact pressure within a predetermined range by appropriately moving a metal indenter by a pressing mechanism based on data detected by the pressure detecting mechanism. Quantitative analysis method for lubricants. 5. The method according to claim 1, wherein the material of the buffer is an elastic rubber.