JPS63106914A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve running performance and durability by forming a thin ferromagnetic metallic film on a nonmagnetic base and depositing a specific polyperfluoroalkaneamide compd. on the thin ferromagnetic metallic film. CONSTITUTION:The recording medium is constituted of the nonmagnetic base 1, the thin ferromagnetic film 2 deposited and formed thereon and a lubricating agent layer 3 contg. the polyperfluoroalkaneamide compd. coated on the surface of the film 2. The polyperfluoroalkaneamide compd. expressed by the formula is used as the lubricating agent. In the formula. R denotes a hydrocarbon group, l, m, n are all integers and are l>=2, 0<=m<=5, n>=3. The sticking of the lubricating agent layer contg. said polyperfluoroalkaneamide compd. on the thin ferromagnetic metallic film is executed by a method of coating a soln. prepd. by dissolving the lubricating agent in a solvent on the surface of the thin ferromagnetic metallic film or spraying the same thereon or conversely immersing the thin ferromagnetic metallic film into said soln. and drying the soln. The coefft. of dynamic friction is thereby decreased and the running stability and wear resistance are improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to vacuum rRWA such as vacuum evaporation and sputtering.
So-called ferromagnetic metal TiJ, in which a ferromagnetic metal thin film is formed as a magnetic layer on a non-magnetic support using techniques such as formation technology.
The present invention relates to a type II magnetic recording medium.

[Summary of the invention]

The present invention provides a magnetic recording medium in which a full ferromagnetic metal is formed as a magnetic layer on a nonmagnetic support. General formula (wherein R represents a hydrocarbon group, 1.m and n are both integers, and l≧2.
0≦m≦5. The present invention aims to provide a magnetic recording medium coated with a polyperfluoroalkane 7-amide compound represented by n≧3) that exhibits excellent runnability, abrasion resistance, and durability under a wide range of usage conditions. It is something.

[Conventional technology]

Conventionally, as a magnetic recording medium, r-
Fog's, Co-containing' (-Fe, O,.

Fe50. , Co-containing Fe, 04+ T F
e@Bertride compound of O1 and Fe5Oa, Co
Powder magnetic materials such as ferromagnetic oxide powders such as bertolide compounds containing CrO, or alloy magnetic powders containing Fe, Co, Ni, etc. as main components are combined with vinyl chloride-vinyl acetate copolymers, polyester resins, Coated magnetic recording media, which are manufactured by coating and drying a magnetic paint dispersed in an organic binder such as a polyurethane resin, 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 type magnetic recording medium not only has excellent coercive force and squareness ratio, and has excellent electromagnetic conversion characteristics at short wavelengths, but also has the ability to make the thickness of the magnetic layer extremely thin, making recording demagnetization possible. It has a number of advantages, including extremely small thickness loss during playback and reproduction, and the ability to increase the packing density of the magnetic material because there is no need to mix an organic binder, which is a non-magnetic material, into the magnetic layer. .

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 substantial contact area is large, making it easy for adhesion phenomena (so-called sticking) to occur and friction. The coefficient becomes larger, etc.
There are many shortcomings in terms of durability, running performance, etc., and their improvement is a major challenge.

In general, a magnetic recording medium is subjected to high-speed relative motion with a magnetic head during the process of recording and reproducing signals, and during this time it must travel smoothly and stably. It is better to have as little wear and damage as possible due to contact with the rad.

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, a ferromagnetic metal thin film to form a protective film.

[Problem that the invention seeks to solve]

By the way, when a protective film is formed by applying a lubricant as described above, this RLI film exhibits good adhesion to the ferromagnetic metal thin film that is the magnetic layer and exhibits a high lubrication effect. required to do so.

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 they cannot fully demonstrate their lubricating effect. I couldn't let it go.

Therefore, the present invention provides a lubricant that maintains adhesion and lubricity under a wide range of usage conditions and maintains a lubricating effect over a long period of time, and provides a magnetic recording medium with excellent running performance and durability. With the goal.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present inventor has conducted intensive research and found that polyperfluoroalkanamide compounds exhibit good lubricating effects over a wide temperature range. Heading This invention has been completed by forming a ferromagnetic metal thin film on a non-magnetic support, and applying a lubricant layer containing the polyperfluoroalkanamide compound as a main component to the ferromagnetic metal thin film. It is characterized by being coated.

That is, the magnetic recording medium of the present invention includes, for example, as shown in FIG. 1, a nonmagnetic support (1) and a ferromagnetic metal thin film 11 deposited thereon. (2), and a lubricant N (3) containing a polyperfluoroalkanamide compound applied to the surface of the ferromagnetic metal thin film (2).

The polyperfluoroalkanamide compound used as a lubricant in the present invention has the general formula % () (wherein R represents a hydrocarbon group, and 1. m, n
are both integers and l≧2.0≦m≦5. n≧3).

In the above general formula (1), the number n of carbon atoms in the perfluoroalkyl group of the polyperfluoroalkanamide compound is 3.
It is desirable that the perfluoroalkyl group is an integer greater than or equal to 3. If the number of carbon atoms in the perfluoroalkyl group is less than 3, the desired lubricating effect cannot be expected.

In addition, the number m of methylene chains is preferably an integer of 0 to 5, and if it exceeds this range, the desired lubricating effect cannot be expected, and the number l of carbamoyl groups is an integer of 2 or more. If it is less than 2, the lubricating effect will be insufficient.

On the other hand, the hydrocarbon R may be a linear or branched alkyl group, an unsaturated aliphatic hydrocarbon group having a double bond, an alicyclic hydrocarbon group, or an aromatic ring. Moreover, this hydrocarbon group R is divalent or more corresponding to the number of the above-mentioned carbamoyl groups.

The above-mentioned polyperfluoroalkanamide compound can be easily synthesized from the corresponding perfluorocarboxylic acid chloride and a commercially available polyamine in the presence of a base. Here, the polyamine is a compound having two or more amino groups.

Further, perfluorocarboxylic acid chloride can be obtained by converting perfluorocarboxylic acid into a chlorine compound using oxalyl chloride, thionyl chloride, or phosphorus pentachloride.

For example, 1,4-butanediamine is dissolved in anhydrous toluene, triethylamine is added in equal moles, and then pentadecafluorooctanoic acid chloride is added dropwise. - After stirring at night, the formed precipitate is sufficiently washed with water and then recrystallized from ethanol to synthesize bis-N-N'-pentadecafluorooctanoylbutanediamine, which is a polyperfluoroalkanamide compound. In fact, when the present inventor carried out the reaction according to the above-mentioned method, bis-N-N'-pentadecafluorooctanoylbutanediamine was synthesized with a yield of 87%. The obtained bis-
The melting point of N-N'-pentadecafluorooctanoylbutanediamine was 135-136°C.

Of course, other polyperfluoroalkanamide compounds can also be used, from ordinary polyamines having two or more amino groups,
For example, it goes without saying that it can be synthesized by a similar method.

The polyperfluoroalkanamide compound synthesized as described above may be used alone as a lubricant, but ζ
It may be used in combination with a conventionally known lubricant to further expand the operating temperature range.

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, perfluoroalkyl carboxylic acid esters and carboxylic acid perfluoroalkyl esters have good low-temperature properties, and are therefore suitable for use in combination with the above-mentioned polyperfluoroalkanamide compounds.

Furthermore, in order to cope with more severe usage conditions and maintain the lubricating effect, an extreme pressure agent is added to the polyperfluoroalkanamide compound at a weight ratio of about 30:0 to 70:30. You can.

When the extreme pressure agent makes partial metal contact in the boundary lubrication area, it reacts with the metal surface due to the accompanying frictional heat, forming a reaction product film to prevent friction and wear. In particular, 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. Halogenated 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 are well known. It is being

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

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, benzophenone and its derivatives hydroxybenzophenone, diaryl ketones such as aminobenzophenone, acridine, 4-quinolitool, heterocyclic compounds containing nitrogen atoms such as kynurenic acid or riboflavin, tocopherol or guanosine, etc. heterocyclic compounds containing an oxygen atom, heterocyclic compounds containing a sulfur atom such as sulfolane, sulfolene or bithione, compounds having a mercapto group such as thiophenol, dithizone or thiooxin, thiocarboxylic acids such as ethanethioic acid or rubeanic acid or their salts , diazosulfide, benzothiazoline, and other thiazole compounds. 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 (
It is most effective if the rust preventive layer (4) is first applied to the surface of 2), and then the lubricant layer (3) is applied in 2N or more parts.

A method for attaching a lubricant layer containing these polyperfluoroalkanamide compounds onto a ferromagnetic metal thin film is to apply a solution obtained by dissolving the above lubricant in a solvent onto the surface of the ferromagnetic metal "iRW!" Alternatively, it may be sprayed, or conversely, a ferromagnetic metal thin film may be immersed in this solution and dried.

Here, the coating amount is preferably 0.5 ■/M to 100 ■/M, more preferably 1 ■/I to 20 ■/d. If this coating amount is too small, , the effects of lowering the coefficient of friction and improving wear resistance and durability are not apparent.On the other hand, if the amount is too large, a phenomenon of sticking occurs between the sliding member and the ferromagnetic metal thin film, which actually worsens 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.

The forms of this non-magnetic support include 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 0.00 to 3000 particles, and the height from the surface of the polymer film is 100 to 3000.
1000 people, density approximately lXl0' ~ l0XIO'
Pieces/1m! shall be. Calcium carbonate (CaCO
silica, alumina, etc. are suitable.

The wrinkle-like protrusions are undulations formed by, for example, applying and drying a dilute solution of resin using a specific mixed solvent, and the height thereof is 0.01 to 10 μm, preferably 0.
．． 03~0.5μm, the shortest distance between protrusions is 0.1~20
Let it be 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. A single substance, a mixture, or a copolymer of various resins such as polyphenylene oxide, phenoxy resin, etc., and those having a soluble solvent are suitable. Then, in a solution in which these resins are dissolved in the good solvent with a resin concentration of 1 to 11,000 ppp, a solvent that is a poor solvent for the resin and has a boiling point higher than the good solvent is added in an amount of 10 to too (fi amount) to the resin. By applying the added solution to the surface of the polymer film and drying it,
A vii layer having very fine wrinkle-like irregularities can be obtained.

The granular protrusions are formed by attaching organic ultrafine particles such as acrylic resin or inorganic fine particles such as silica or metal powder in a spherical or semispherical shape. The height of this granular protrusion is
50 to 500 people, the density is 1X10' to 50X10''pieces/m''N degrees t4° If at least one of these protrusions is formed, the surface properties of the ferromagnetic metal thin film that is the magnetic layer can be controlled, but 2 Combining more than one species increases the effect, and in particular, if wrinkle-like protrusions and squabble-like protrusions are formed on a base film provided with mountain-like protrusions, durability and runnability 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 1 crane 2
It is preferable that the number is 1×10S to 1×10′ on average.

Further, the ferromagnetic metal thin film that is the magnetic layer is formed as a continuous film by a vacuum thin film forming technique such as a vacuum evaporation method, an ion blating method, or a sputtering method.

In the vacuum evaporation method described above, 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 the evaporated metal (
Generally, in order to obtain a high coercive force, an oblique evaporation method is employed in which the ferromagnetic metal material is deposited obliquely to the substrate. or,
It also includes those in which the above-mentioned vapor deposition 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 RFFa-discharge are caused in an inert gas atmosphere of 10-4 to 10-' Torr, and the above-mentioned ferromagnetic metal material is evaporated during the discharge. It is to let them do so.

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

In the case of this sputtering method, Cr or W is used.

A base film such as V may be formed in advance.

In any of the above methods, Bl, Sb, Pb, Sn, Ga, and In are deposited on the substrate in advance.

By pre-depositing a base metal layer such as Cd, Ge, St, T1, etc., and depositing the film in a direction perpendicular to the substrate surface, an excellent in-plane method can be achieved without the orientation of magnetic anisotropy. It is possible to form a magnetic layer, and is suitable for use in, for example, magnetic disks.

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 Nt, C.

-Ni alloy, Co-Pt alloy, Co-Nt-Pt alloy,
Fe-Co alloy, Fe-Ni alloy, Fe-Go-Ni alloy, Fa-Co-B alloy, Co-N1-Fe-B alloy,
Examples include Co--Cr alloys and those containing metals such as Cr and AJ. In particular, when a Co--Cr alloy is used, a perpendicularly magnetized 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 back coat layer (5) is formed on the side opposite to the surface on which the ferromagnetic metal thin film (2) and lubricant layer (3) are provided on the nonmagnetic support (1). The back coat layer (5) may be formed of a binder resin such as vinyl chloride-vinyl acetate, phenolic resin or poritzized vinyl, polyurethane resin or butadiene copolymer, and carbon for imparting conductivity. A back coat paint made by mixing and dispersing a powder component such as a system fine powder or an inorganic pigment added to control surface roughness and improve durability in an organic solvent such as acetone, methyl ethyl ketone or benzene is applied to the non-magnetic support surface. It is formed by applying it to

A lubricant may be used in the back coat layer (5). In this case, the lubricant may be added internally into the bank coat layer (5), or the lubricant may be added on the back coat layer (5). There is a way to apply it. In any case, as the lubricant, conventionally known lubricants such as fatty acids, fatty acid esters, fatty acid amides, metal soaps, aliphatic alcohols, paraffins, and silicones can be used. Furthermore, a polyperfluoroalkanamide compound may be used as a lubricant in this bank coat layer (5) as in the previous lubricant layer (2).

[Effect]

Polyperfluoroalkanamide compounds exhibit good lubrication over a wide temperature range, and therefore, by coating them on ferromagnetic metal thin films, the coefficient of friction of ferromagnetic metal thin film magnetic recording media can be significantly reduced. be done.

〔Example〕

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

Example 1 Co was deposited on a 14 μmq polyethylene terephthalate film by oblique evaporation to form a ferromagnetic metal thin film with a thickness of 1000 μm.

Next, Bis-N was applied to the surface of this ferromagnetic metal thin film.

N゛-Pentadecafluorooctanoylbutanediamine (CJ + 5cONH (CL) JHCOC+F
+s) so that the coating amount is 5■/d, and
A chimple tape was produced by cutting the tape into a width of /2 inches.

Example 2 A sample tape was prepared in the same manner as in Example 1 using bis-N,N'-pentadecafluorooctanoyl-p-phenylenediamine instead of bis-N,N"-pentadecafluorooctanoylbutanediamine. .

Example 3 Bis-N,N'-pentadecafluorooctanoyl octanediamine CC instead of bis-N,N'-pentadecafluorooctanoylbutanediamine? F
A sample tape was prepared in the same manner as in Example 1, except that 5cONH(CL) JHCOCJ + s) was used.

Example 4 Tris-N,N" instead of bis-N,N'-pentadecafluorooctanoylbutanediamine.

Using N”-pentadecafluorooctanoyltriaminobenzene (C,H3(NIICOC MaF+5)s),
A sample tape was produced in the same manner as in Example 1 except for the above.

Example 5 A sample tape was prepared in the same manner as in Example 1 using bis-N,N'-pentadecafluorooctanoylcyclohexanediamine instead of bis-N,N'-pentadecafluorooctanoylbutanediamine.

Example 6 Bis-N,N'-nonadecafluorodecanoylbutanediamine (CJ I 9C) instead of bis-N,N'-pentadecafluoro-octanoylbutanediamine
A sample tape was prepared in the same manner as in Example 1, except that ONH(CHt) 4NHCOCgF + q) was used.

For each sample tape produced, the dynamic friction coefficient and shuttle durability were measured under the following conditions: 25°C, 50% relative humidity (RH), and -5°C. This dynamic friction coefficient was tested by using a guide pin made of stainless steel (SUS304) and feeding it at a speed of 5 m/see under a constant tension. 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 above table, under the conditions of each example of the present invention, the coefficient of dynamic friction was small, the running was extremely stable, and no damage was observed on the tape surface even after running back and forth 100 times. In addition, the still durability is extremely good (no 13 dB decrease in output was observed even after 150 shuttle runs.On the other hand, with the comparative tape without a lubricant layer, the friction coefficient was lower when running back and forth. As the number of times increased, the size increased, running was unstable, tape friction was observed, and durability was poor.

〔Effect of the invention〕

As is clear from the above description, in the present invention,
Since a polyperfluoroalkanamide compound is used as a lubricant for ferromagnetic metal thin film magnetic recording media, it is possible to reduce the force *t* coefficient even under a wide range of 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. FIG. 3 is an enlarged sectional view of a main part showing still another example of the configuration of a magnetic recording medium to which the present invention is applied. 1...Nonmagnetic support 2...Ferromagnetic metal YT film 3...Lubricant layer 4...Rust preventive layer 5...Bank coat layer

Claims (1)

[Claims] A ferromagnetic metal thin film is formed on a non-magnetic support, and on the ferromagnetic metal thin film there is a general formula ▲ mathematical formula, chemical formula, table, etc. ▼ (However, in the formula, R represents a hydrocarbon group. 1. A magnetic recording medium coated with a polyperfluoroalkanamide compound represented by the following formula, where l, m, and n are all integers and l≧2, 0≦m≦5, and n≧3.