JPS6371923A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To form a magnetic recording medium which exhibits excellent running property, wear resistance and durability under all use conditions by depositing perfluoroalkyl sulfonic acid tetraalkyl ammonium salt on a thin ferromagnetic metallic film which is a magnetic layer. CONSTITUTION:This magnetic substrate is constituted by forming the thin ferromagnetic metallic film 2 on a nonmagnetic substrate 1 and depositing a lubricating agent layer 3 essentially consisting of the perfluoroalkyl sulfonic acid tetraalkyl ammonium salt on the thin ferromagnetic metallic film 2. The perfluoroalkyl sulfonic acid tetraalkyl ammonium salt to be used as the lubricating agent is the compd. expressed by CnF2n+1SO3<->N<+>R4 (where R denotes a hydrocarbon group, n is >=4 integer). The lubricating agent, the adhesiveness and lubricating effect of which are maintained under the any use conditions and which maintains the lubricating effect for a long period of time is thereby formed and the magnetic recording medium having the excellent running property and durability is obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a so-called magnetic layer in which a ferromagnetic metal thin film is formed as a magnetic layer on a non-magnetic support by vacuum thin film forming techniques such as vacuum evaporation and sputtering. The present invention relates to a ferromagnetic metal thin film type magnetic recording medium.

[Summary of the Invention] The present invention provides a magnetic recording medium in which a ferromagnetic metal thin film is formed as a magnetic layer on a non-magnetic support. Coated with alkylsulfonic acid tetraalkylammonium salt for excellent running performance under all conditions of use.

The objective is to provide a magnetic recording medium that exhibits wear resistance and durability.

[Conventional technology]

Conventionally, as a magnetic recording medium, non-%'A i'! rF containing rFe2O:++Co on the support
"20j+F e yoa, F ez containing Co
oa+T F Heltride compound of e2o3 and Fe, O, Co-containing heltride compound, CrO
Oxide ferromagnetic powder such as □ or Fe, Co,
A powder magnetic material such as an alloy magnetic powder whose main component is Ni etc. is separated into an organic binder such as a vinyl chloride-vinyl acetate copolymer, polyester + Coated magnetic recording media, which are produced by drying, are widely used.

On the other hand, with the increasing demand for high-density magnetic recording, ferromagnetic metal materials such as Co-Ni alloys have been made into polyester by plating or vacuum thin film formation technology (vacuum evaporation, sputtering, ion blating, etc.). A so-called ferromagnetic metal thin film type magnetic recording medium, which is directly deposited on a non-magnetic support such as a film or a polyimide film, has been proposed and is attracting attention. This ferromagnetic metal thin film magnetic recording medium not only has excellent coercive force and squareness, and has excellent electromagnetic conversion characteristics at short wavelengths (also, since the thickness of the magnetic layer can be made extremely thin, it is possible to reduce recording loss). It has a number of advantages, such as extremely low thickness loss during magnetization and reproduction, and the ability to increase the packing density of magnetic material because there is no need to mix an organic binder, which is a non-magnetic material, into the outer layer. There is.

However, in the above-mentioned ferromagnetic metal thin film type magnetic recording medium, the surface smoothness of the magnetic layer is extremely good, so the effective contact area is large (as a result, adhesion phenomenon (so-called sticking) easily occurs. or the coefficient of friction increases, etc.
It has many shortcomings in terms of durability, running performance, etc., and improving them is a major issue.

In general, a main air recording medium is subjected to high-speed relative motion with a magnetic head during the recording and reproducing process of magnetic signals, and must run smoothly and stably. Also, it is better to minimize wear and damage caused by contact with the magnetic head.

For example, attempts have been made to improve the durability and runnability by applying a lubricant to the surface of the magnetic layer of the magnetic recording medium, that is, the three ferromagnetic metal films to form a protective film.

[TA problem that the invention attempts to solve]

By the way, when a protective film is formed by applying a lubricant as described above, the strength of this protective film is that it exhibits good adhesion to the thin metal film and has high lubricity. It is required to be effective.

In addition, these adhesion properties and lubrication effects must be excellent both under hot and humid conditions, such as in tropical and subtropical regions, and under low-temperature conditions, such as in cold regions.

However, the operating temperature range of conventionally widely used lubricants is limited, and in particular, many of them solidify or freeze at low temperatures such as 0 to -5℃, so it is difficult to fully demonstrate their lubricating effect. I couldn't.

Therefore, the present invention provides a 7111 lubricant that maintains adhesion and lubricity under any usage conditions and maintains a lubricating effect over a long period of time, and provides a magnetic recording medium with excellent runnability and durability. The purpose is to

[Means for Solving the Problems] As a result of intensive research to achieve the above-mentioned object, the present inventor found that a tetraalkylammonium salt of perfluoroalkylsulfonic acid exhibits a good lubricating effect over a wide temperature range. As shown in FIG. 1, ferromagnetic gold RgJv (2) is formed on a non-stick support (1), and the ferromagnetic metal It is characterized in that a lubricant layer (3) whose main component is a perfluoroalkylsulfonic acid tetraalkylammonium salt is adhered to the thin film (2).

The perfluoroalkylsulfonic acid tetraalkylammonium salt used as a lubricant in the present invention has the general formula % (in the formula, R represents a hydrocarbon group, and n is an integer of 4 or more.) It is a compound represented by

By forming the perfluoroalkyl sulfonic acid into a tetraalkylammonium salt, its solubility in organic solvents can be increased compared to ordinary ammonium salts.
Solubility is improved by just including a small amount of alcohol.

Here, in the above general formula (I), the number n of carbon atoms in the perfluoro group of the perfluoroalkylsulfonic acid tetraalkylammonium salt is desirably a Bq number of 4 or more, and the number n of carbon atoms in the perfluoro group is less than 4. In some cases, the desired lubrication effect cannot be expected. On the other hand, R may be any hydrocarbon group, and may be saturated, unsaturated, monolinear, or branched.

The above-described tetraalkylammonium perfluoroalkylsulfonate salt may be used alone as a lubricant, but may also be used in combination with a conventionally known lubricant to further expand the temperature range of use.

The lubricants used include fatty acids or their metal salts;
Fatty acid amide, fatty acid ester, fatty alcohol or its alkoxide, fatty amine, polyhydric alcohol,
Sorbitan ester, mannisotane ester, sulfurized fatty acid, aliphatic mercaptan, modified silicone oil, perfluoroalkyl ethylene oxide, perfluoropolyethers, higher alkyl sulfonic acid or its metal salt, perfluoroalkyl sulfonic acid or its ammonium salt, or Examples include metal salts thereof, perfluoroalkylcarboxylic acids or metal salts thereof.

In particular, the general formula C, F, □, C0OR" (however, m in the formula
represents an integer of 6 to 10, and R represents a hydrocarbon group having 1 to 25 carbon atoms. ) or a perfluoroalkyl carboxylic acid ester represented by -m formula R" C00(CHz)=C
k F It is suitable for

Furthermore, in order to cope with more severe usage conditions and maintain the lubricating effect, the above-mentioned perfluoroalkylsulfonic acid tetraalkylammonium salt is mixed with a film at a weight ratio of about 30:0 to 70:3). A pressure agent may also be used.

When the extreme pressure agent mentioned above makes partial metal contact in the boundary lubrication area, it reacts with the metal surface due to the accompanying frictional heat and forms a reaction product film, thereby providing anti-friction and wear prevention effects. Phosphorus-based extreme pressure agents such as phosphate esters, phosphite esters or phosphate ester amine salts, sulfur-based extreme pressure agents such as sulfurized oils and fats, monosulfides or polysulfides, iodine compounds, bromine compounds or chlorine compounds, etc. Halogen-based extreme pressure agents, organometallic extreme pressure agents such as thiophosphates, thiocarbamates, or metal alkyl dithiocarbamates, and complex extreme pressure agents such as dialkylthiophosphate amines, thiophosphates, or thiophosphites, etc. Are known.

Moreover, in addition to the above-mentioned lubricants and extreme pressure agents, a rust preventive agent may be used in combination, if necessary.

As the rust preventive agent that can be used, any rust preventive agent that is normally used as a rust preventive agent for this type of magnetic recording medium may be used, such as dihydric phenol.

Phenols such as alkylphenol or nitrosophenol, naphthols such as pure naphthol or nitro-, nitroso-, amino-, or halogeno-substituted naphthol, methylquinone, hydroxyquinone.

quinones such as aminoquinone, nitroquinone or halogenoquinone; diarylketones such as henzphenone and its derivatives hydroxyhensiphenone and aminohensiphenone; heterocyclic compounds containing a nitrogen atom such as acridine, 4-quinolitool, kynurenic acid or riboflavin; Heterocyclic compounds containing an oxygen atom such as tocopherol or guanosine, heterocyclic compounds containing a sulfur atom such as sulfolane, sulfolene or bithione, compounds having a mercapto group such as thiophenol, dithizone or thiooxine, thiocarboxylic compounds such as entathioic acid or ruheanoic acid. Examples include acids or salts thereof, thiazole compounds such as diazusulfide, and hendithiazoline. The above-mentioned rust preventive agent may be used in combination with a lubricant, but for example, as shown in FIG. 2, a ferromagnetic metal thin film (2
It is most effective if the rust preventive layer (4) is first applied to the surface of the rust preventive layer (4), and then the lubricant layer (3) is applied in two or more layers.

As a method for attaching a lubricant layer containing these perfluoroalkyl sulfonic acid tetraalkylammonium salts onto a single ferromagnetic metal film, the lubricant layer containing the perfluoroalkyl sulfonic acid tetraalkylammonium salt is prepared by dissolving the above-mentioned screw/bond agent in 7 volumes. The solution may be applied or sprayed onto the surface of the raw ferromagnetic metal thin film, or conversely, the ferromagnetic metal 1 film may be dipped in this solution and dried.

Here, the coating amount is 0.5/ze~100TN/n
(Preferably, 1■/d to 20■/d is more preferable. If this coating amount is too small, the effects of lowering the friction coefficient and improving wear resistance and durability will not be realized. On the other hand, if the amount is too large, a sticking phenomenon will occur between the sliding member and the ferromagnetic metal thin film, which will actually worsen running performance.

The magnetic recording medium to which the present invention is applied is one in which a ferromagnetic metal thin film is provided as a magnetic layer on a non-magnetic support, and the material for the non-magnetic support may include polyesters such as polyethylene terephthalate, Polyolefins such as polyethylene and polypropylene, cellulose derivatives such as cellulose triacetate, cellulose diacetate, and cellulose acetate butyrate, vinyl resins such as polyvinyl chloride and polyvinylidene chloride, plastics such as polycarbonate, polyimide, and polyamideimide, aluminum alloys, Examples include light metals such as titanium alloys and ceramics such as alumina glass.

In the wet state of this non-magnetic support, film, sheet,
It may be a disk, card, drum, etc.

The surface roughness of the non-magnetic support may be controlled by forming one or more types of protrusions such as mountain-like protrusions or wrinkle-like protrusions on the surface of the non-magnetic support.

For example, the above-mentioned mountain-like protrusions have a particle size of 5 when forming a polymer film.
It is formed by internally adding about 0.00 to 3000 particles, and the height from the polymer film surface is 100 to 3000.
1000 people, density approximately I X 10'~10'X1
0' pieces/tomo 2. As the inorganic fine particles used to form the mountain-like protrusions, calcium carbonate (CaCO), silica, alumina, etc. are suitable.

The above-mentioned wrinkle-like protrusions are undulations formed by, for example, diluting a resin using a specific mixed solvent, applying and drying the resin, and have a height of 0.01 to 10μm, preferably 0.03 to 10μm. 0.5 μm, the shortest distance between protrusions is 0.1-2
It is set to 0 μm. Examples of resins used to form these wrinkle-like projections include saturated polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyamides, polystyrene, polycarbonates, polyacrylates, polysulfones, polyethersulfones, polyvinyl chloride, polyvinylidene chloride, and polyvinyl butyral. , polyphenylene oxide, phenoxy resin, etc.,
Mixtures or copolymers with soluble solvents are suitable. Then, a resin solution containing these resins in a good solvent of 1 to 11,000 pp is used.
By applying and drying a solution containing 10 to 100 times the amount of solvent 8 (which is a poor medium for the resin and has a higher boiling point than the good solvent mentioned above) to the resin, it can be applied to the surface of the polymer film and dried. A thin surface with fine wrinkle-like unevenness can be obtained.

The granular protrusions are formed by attaching ultrafine organic particles such as acrylic resin, or undivided particles such as silica or metal powder in a spherical or hemispherical shape. The height of this granular protrusion is
50 to 500 people, density 1 x 106 to 50 x 10' pieces/
It should be about sm 2.

Forming at least one type of these protrusions (d) controls the surface properties of the ferromagnetic metal thin film that is the outer layer, but combining two or more types increases the effect. By forming a protrusion and a protrusion, durability and running properties are greatly improved.

In this case, the overall height of the protrusion is 100 to 200
It is preferable that the number is within the range of 0 people, and the density is 1s1
It is preferable that the average number per 2 is 1XIO3 to 1X10'.

Further, the magnetic layer, which is a strong ≦1 metal a film, can be prepared using a vacuum 7i! Formed as a continuous film using film formation technology.

In the vacuum evaporation method, a ferromagnetic metal material is evaporated by resistance heating, high frequency heating, electron beam heating, etc. under a vacuum of 10-' to 10-Torr, and a thin metal (
Generally, in order to obtain a high coercive force, an oblique deposition method is employed in which the ferromagnetic metal material is deposited obliquely to the base material. or,
This also includes those in which the above-mentioned stem attachment is performed in an oxygen atmosphere in order to obtain higher coercive force.

The above-mentioned ion brating method is also a type of vacuum evaporation method, in which DC glow discharge and RF glow discharge are caused in an inert gas atmosphere of 10-4 to 10-' Torr, and the above-mentioned ferromagnetic metal material is heated during the discharge. It is to let them do so.

The above sputtering method uses 10-' to 10-' Torr.
A glow discharge is generated in an atmosphere mainly composed of argon gas, and the generated argon gas ions are used to knock out atoms on the target surface. There are sputtering methods, magnetron sputtering methods using magnetron discharge, and the like.

In this case, Cr and W are removed.

A base film such as ~' may be formed in advance.

In any of the above methods, Bi, Sb, Pb, Sn, Ga, and In are preliminarily deposited on the substrate.

By depositing a base metal stone such as Cd, Ge, Si, Te, etc., and forming the film from the direction perpendicular to the radix plane, an excellent in-plane method can be obtained without the orientation of magnetic anisotropy ( It is possible to form an n-type layer, and is suitable for forming a 411-layer disk, for example.

When forming a metal magnetic thin film using such vacuum thin film forming technology, the ferromagnetic metal materials used include Fe,
In addition to metals such as co and Ni, c.

-Ni alloy, Co-Pt alloy, Co-Ni-Pt alloy, Fe-Co alloy + FeNi alloy, Fe-
Co-Ni alloy, Fe-Co-B alloy, Go-Ni-F
e-B alloy + Co Cr alloy or C
Examples include those containing metals such as r, AA, etc. In particular, when a Co--Cr alloy is used, a vertical film is formed.

The thickness of the magnetic layer formed by such a method is 0.
It is about 0.04 to 1 μm.

In addition, as shown in FIG. 3, a so-called bank coat layer ( 5)
may be formed. The back coat layer is made of vinyl chloride-vinyl acetate, phenol, polyvinyl fluoride, polyurethane resin or binder resin such as butadiene copolymer, and carbon-based fine powder or surface for imparting conductivity. By applying a back coat paint, which is made by mixing and dispersing powder components such as inorganic pigments added to control roughness and improving durability in an organic solvent such as acetone, methyl ethyl ketone or benzene, on the surface of a non-magnetic support. It is formed.

A lubricant may be used in the aforementioned backcoat layer. In this case, there is a method of internally adding a lubricant to the back coat layer, or a method of depositing a lubricant on the back coat layer. In any case, the above-mentioned lubricants include fatty acids,
Conventionally known lubricants such as fatty acid esters, fatty acid amides, metal soaps, fatty alcohols, paraffins, and silicones can be used.

[Effect]

A good l? The friction coefficient is reduced by applying pressure to the I-sliding force.

In particular, perfluoroalkylsulfonic acid tetraalkylammonium salts exhibit good lubricating effects even at low temperatures.

〔Example〕

Hereinafter, specific examples of the present invention will be described, but the present invention is not limited to these examples.

A ferromagnetic metal thin film type magnetic recording medium was fabricated using perfluoroalkylsulfonic acid tetraalkylammonium salt.

Example 1 CO was deposited on a polyethylene terephthalate film having a thickness of 14 μm by an oblique evaporation method to form a ferromagnetic metal thin film having a thickness of 1000 μm.

Next, perfluorooctanesulfonic acid tetraethylammonium salt (C@F
tffSO3-N'(Ctlls)t) was dissolved in a Freon solution and coated at a coating amount of 5 mg/m+, and cut into 8 mm width to prepare a sample tape.

Example 2 CO was deposited on a 14 μm Fj polyethylene terephthalate film by an oblique deposition method to form a ferromagnetic metal thin film with a thickness of +y11000.

Next, perfluorodecanesulfonic acid tetraethylammonium salt (C+o
Fz+SO]-N'(CzHs)n) as freon C't? t), the application amount is 5■/I'1
1, and cut it into 8 mm width to make a sample tape.

Example 3 Go was deposited on a 14 μm thick polyethylene telescrate film by oblique vapor deposition to form a 1000 μm thick ferromagnetic metal thin film.

Next, perfluorooctane sulfonic acid tetramethylammonium salt (Cfi
F+tSOi-N'(CHi)4) into freon) skin? Yong, i! The sample tape was prepared by coating the sample tape at a coating interval of 5 mm/M and cutting it into a width of 8 mm.

For each sample tape produced, 'iL degree 25℃
, 50% relative humidity (RH), and −5° C. The dynamic friction coefficient and shuttle durability were measured. This coefficient of dynamic friction was determined by applying a constant tension to 5 mm/sec using a guide pin made of stainless steel (SUS304).
The test was conducted by feeding at a speed of c. In addition, the shuttle durability was evaluated by running the shuttle for 2 minutes each time, and determining the number of shuttle runs until the output decreased by 13 dB. Still durability was evaluated by evaluating the decay time for the output to -3 dB in a pause state. As a comparative example, a blank tape to which no lubricant was applied was also measured.

The results are shown in the table below.

As is clear from the table above, under the conditions of each example of the present invention, the coefficient of dynamic friction was small and running was extremely stable, and no damage was observed on the tape surface even after running back and forth 100 times. Furthermore, the still durability was extremely good, and even after 150 shuttle runs, no decrease in output by 13 dB was observed. On the other hand, in the tape of the comparative example without a lubricant layer, the friction coefficient increased as the number of reciprocating runs increased, the running was unstable, tape friction was observed, and the durability was poor.

〔Effect of the invention〕

As is clear from the above description, in the present invention,
Perfluoroalkylsulfonic acid tetraalkylammonium salt is used as a lubricant for ferromagnetic metal thin film magnetic recording media, so the coefficient of dynamic friction can be reduced under any temperature conditions, improving running stability and wear resistance. A magnetic recording medium with excellent properties can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an enlarged cross-sectional view of a main part showing an example of the structure of a magnetic recording medium to which the present invention is applied. FIG. 2 is an enlarged cross-sectional view of a main part showing another example of the structure of a magnetic recording medium to which the present invention is applied. , FIG. 3 is an enlarged cross-sectional view of a main part showing still another configuration example of a magnetic recording medium to which the present invention is applied. 1...Nonmagnetic support 2...Ferromagnetic metal thin film 3...Lubrication Agent layer 4... Rust inhibitor layer 5... Back coat layer

Claims (1)

[Claims] 1. A magnetic recording medium comprising a ferromagnetic metal thin film formed on a non-magnetic support, and a perfluoroalkylsulfonic acid tetraalkylammonium salt deposited on the ferromagnetic metal thin film.