JPS62103829A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To maintain adhesiveness and lubricity and to improve wear resistance and runnability by forming a thin ferromagnetic metallic film on a nonmagnetic base and depositing a lubricating agent layer contg. a perfluoroalkylcarboxylate and fatty acid amide on the thin magnetic metallic film. CONSTITUTION:The thin ferromagnetic metallic film is formed on the nonmagnetic base and the lubricating agent contg. the perfluoroalkylcarboxylate and fatty acid amide is deposited on the thin magnetic metallic film. The perfluoroalkylcarboxylate is expressed by the formula CnF2n+1COOR (where n denotes 6-10 integer, R denotes a hydrocarbon group of 1-25C) and is easily synthesized by bringing a perfluoroalkylcarboxylic acid and corresponding alcohol into reaction. The fatty acid amide is exemplified by a satd. fatty acid amide and unsatd. fatty acid amide. The compounding ratio of the fatty acid amide is preferably 30:70-70:30wt. The amt. of the lubricating agent to be coated is preferably 0.5-100mg/m<2>.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a 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 so-called ferromagnetic metal thin film type magnetic recording medium.

[Summary of the invention]

The present invention provides a magnetic recording medium formed by forming a ferromagnetic metal TEX film as a magnetic layer on a non-magnetic support, in which a perfluoroalkyl carboxylic acid ester and a fatty acid amide are used as a lubricant for the ferromagnetic metal thin film that is the magnetic layer. Adhesive as a coating, with good runnability and abrasion resistance over a wide range of operating temperatures.

This improves durability.

C. Prior Art] Traditionally, magnetic recording media have been made by recording T-
r-Fe20J containing Felon and Co.

Feloa+r-Fe containing Fe30a+Co
Powder magnetic materials such as bertride compounds of zo3 and Fe3O4, heldride compounds containing CO, oxide ferromagnetic powders such as Cr0z, or alloy magnetic powders whose main components are Fe, Co, Ni, etc., are converted into vinyl chloride-vinyl acetate. System Copolymer 1 A sauce-type magnetic recording medium is widely used, which is produced by applying and drying a magnetic paint dispersed in an organic binder such as a polyester resin or a polyurethane resin.

On the other hand, with the increasing demand for high-density magnetic recording, ferromagnetic metal materials such as Co-Ni alloys have been developed using plating and vacuum thin film forming techniques (vacuum evaporation, sputtering, ion plating, etc.). A so-called ferromagnetic metal thin film type magnetic recording medium, which is directly deposited on a non-magnetic support such as a polyester 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 many advantages, such as extremely small thickness loss during playback and reproduction, and the ability to increase the packing density of the magnetic material since 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, since the surface smoothness of the magnetic layer is extremely good,
There are many drawbacks in terms of durability, runnability, etc., such as an increase in the actual contact area, a tendency to cause adhesion (so-called sticking), and an increase in the coefficient of friction, and improvement of these problems has become a major issue. In general, a magnetic recording medium is subjected to high-speed relative motion with a magnetic head during the process of recording and reproducing magnetic signals, and must run smoothly and stably at this time. Further, it is better to minimize wear and tR scratches caused by contact with the magnetic head.

Therefore, for example, it is possible 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.
The ceremony is being watched.

[Problem that the invention seeks to solve]

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

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 lubricants become solid or freeze at low temperatures such as 0 to -5°C. I couldn't let it go.

Therefore, it is an object of the present invention to provide a magnetic recording medium that maintains adhesion and lubricity under any usage temperature conditions, has a small friction coefficient, and has excellent wear resistance and runnability. do.

(Means for Solving the Problems) As a result of intensive research, the present inventors have found that the ester portion of perfluoroalkyl carboxylic acid has a long-chain alkyl group or a double bond. By combining a perfluoroalkylcarboxylic acid ester into which either an alkyl group or a branched alkyl group has been introduced and a fatty acid amide, a superior lubricating effect is exhibited compared to when used alone, and when used simultaneously.
They discovered that it is possible to expand the magnetic band and completed the present invention, in which a ferromagnetic metal thin film is formed on a non-magnetic support, and the ferromagnetic raw metal thin film is permeated. It is characterized in that a lubricant layer containing a fluoroalkyl carboxylic acid ester and a fatty acid amide is deposited.

The perfluoroalkyl carboxylic acid ester used in the present invention has the general formula % (in the formula, n represents an integer of 6 to 10, and R represents a hydrocarbon group having 1 to 25 carbon atoms). It can be easily synthesized by reacting a perfluoroalkylcarboxylic acid with a corresponding alcohol.

In the above perfluoroalkylcarboxylic acid ester, the number of carbon atoms n in the perfluoroalkylcarboxylic acid moiety is 6.
-IO is preferred. This carbon number n is 6
If the number of carbon atoms is less than 10, the lubricating effect will be insufficient, and if the number of carbon atoms exceeds 10, it will solidify in a low temperature range, resulting in a decrease in the lubricating effect under low temperature conditions. The same applies to the number of carbon atoms in the hydrocarbon group of the ester moiety, and in the above general formula, it is preferable that the number of carbon atoms in the hydrocarbon iR is 1 to 25.
More preferably, it has 9 to 25 carbon atoms.

If the number of carbon atoms in the hydrocarbon group R is less than 9, the lubricating effect will be insufficient, and if it exceeds 25, the lubricating effect at low temperatures will be lost. Note that this hydrocarbon group R may be a long-chain alkyl group, a divided alkyl group, or an alkylene chain having a double bond.

On the other hand, fatty acid amides used in the present invention include saturated fatty acid amides and unsaturated fatty acid amides. Saturated fatty acid amides include caproic acid amide, caprylic acid amide, capric acid amide, lauric acid amide, tridecylic acid amide, mystylic acid amide, pentadecyl acid amide, palmitic acid amide, heptadecylic acid amide,
Examples include stearic acid amide, nonadecanoic acid amide, arachidic acid amide, eicosanoic acid amide, heneicosanoic acid amide, behenic acid amide, and the like. Examples of unsaturated fatty acid amides include dodecenoic acid amide, tetradecenoic acid amide, hexadecenic acid amide, occudecenoic acid amide, oleic acid amide, elaidic acid amide, eicosenoic acid amide, tocosenoic acid amide, linoleic acid amide, linoleic acid amide, etc. Examples include those having one or more saturated double bonds.

The blending ratio of the above-mentioned perfluoroalkyl carboxylic acid ester and fatty acid amide is 30 nia 0 to 7 in terms of weight ratio.
Preferably it is 0:30. In addition to the above-mentioned perfluoroalkyl carboxylic acid ester and fatty acid amide,
Conventionally known lubricants may be used in combination.

As a method for attaching the lubricating layer containing these perfluoroalkyl carboxylic acid esters and fatty acid amides to the ferromagnetic metal thin film, the above lubricant is dissolved in a solvent and the resulting solution is applied to the surface of the ferromagnetic metal thin film II. The ferromagnetic metal 7M film may be coated or sprayed on the solution, or conversely, the ferromagnetic metal 7M film may be immersed in this solution and dried.

Here, the coating amount is 0.5+ng/n (~l OO
It is preferably nw/d, and more preferably 1/- to 20/d. If the coating amount is too small, the effect of lowering the coefficient of friction and improving wear resistance and durability will not be achieved. On the other hand, if it is too large, a sticking phenomenon will occur between the sliding member and the ferromagnetic metal thin film. On the contrary, the running performance deteriorates.

A magnetic recording medium to which the present invention is applied uses a ferromagnetic metal as a magnetic layer on a non-magnetic support. The material for the nonmagnetic support includes polyesters such as polyethylene terephthalate, polyolefins such as polyethylene and polypropylene, and 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, light metals such as aluminum alloys and 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.

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

The vacuum evaporation method described above involves resistance heating, high frequency heating, and Ti deposition of a ferromagnetic metal material under a vacuum of 10-' to 10-'' Torr.

The evaporated metal (ferromagnetic metal material) is deposited on the disk substrate by evaporation using beam heating, etc.
Generally, in order to obtain high coercive force, an oblique mounting method is employed in which the ferromagnetic metal material is obliquely deposited on the substrate. Alternatively, it also includes those in which the 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 rejuvenation method, in which DC glow discharge and RF glow discharge are caused in an inert gas atmosphere of 10-' to 10-'' Torr, and the above-mentioned ferromagnetic metal material is heated during the discharge. This is to adjust the light.

The above sputtering method uses 1(1'□3~IOITor
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 is a sputtering method, a magnetron discharge method using magnetron discharge, and the like.

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

A base film such as V 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 pre-depositing a base metal layer such as Cd, Ge, Si, Tl1, 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 formation technology, the ferromagnetic metal thin film used is Fe,
In addition to metals such as Co and Ni, C.

-N1 alloy, Co-Pt alloy, Co-Ni-Pt alloy,
Fe-Co alloy, FeNi alloy, Fe-Co-Ni alloy, )'e-Co-B alloy, co-Ni-Fe-8 alloy,
Co-Cr alloy or these with Cr, AI! Examples include those containing the metal of the hat. 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.

[Effect]

The lubricant layer containing perfluoroalkyl carboxylic acid ester and fatty acid amide firmly adheres to the ferromagnetic metal thin film, exhibits a good lubricating effect, and reduces the coefficient of friction. In particular, perfluoroalkyl carboxylic acid esters exhibit good lubrication effects even at low temperatures, and fatty acid amides exhibit good lubricity at room temperatures, so the range of operating temperatures can be expanded.

Ru.

〔Example〕

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

Synthesis Example 1゜Nonadecafluorodecanoic acid isostearyl ester C1
13(CH12), 1-Ctl-CH2-OCG-(
CFz) 8CF+(C1lz), Ctl3 Isostearyl alcohol and nonadecafluoro]' An ester reaction was carried out with kanoic acid in toluene using p-4 luenesulfonic acid as a catalyst. That is, after heating under reflux for 1 hour,
Water in the solvent was removed over a period of 3 hours, and toluene was removed using an evaporator under reduced pressure, followed by purification by placing in vacuum. (Isostearyl alcohol was synthesized by converting commercially available isostearic acid into n-butyl ester and then reducing it with lithium aluminum hydride.) The boiling point bp of the obtained fraction was 140-145°C, 10.2 mm, 11 g. there were.

In addition, the product can be confirmed by infrared spectroscopy (IRE).

The analysis was carried out by nuclear resonance spectrometry (NMR) and mass spectrometry (MASS). As a result, 121O~1380c, m-
Absorption characteristic of the CF bond is observed at 1780 cm-', absorption due to stretching vibration of CH is observed at 2910 cm-', and molecular ion peak M is observed in the mass spectrum by chemical ion method.

was found in 765, so this structure was determined.

Synthesis Example 2゜Pentadecafluorodecanoic acid isostetyl ester C
1h(CIl□)a-CI-CHz-OCO-(CFz
) 6CF3(CL)6cL In the same manner as in Synthesis Example 1 above, isostearyl alcohol was reacted in toluene using P-toluenesulfonic acid as a catalyst.

b9 1 2 0" l 3 4'C (0.2m
ml1gl) IR 1200-1400cm-'1
7 8 0 cm-' 2 9 2 0 cm-'M' 665 Synthesis Example 3 Pencudecafluorooctanoic acid isononyl ester (C
1h) 3C(CH,)C11(C113)CH2C1
120CO(CF2), CF2 By the same method as in Synthesis Example 1 above, isononyl alcohol and pentadecafluorooctanoic acid were reacted in toluene using p-toluenesulfonic acid as a catalyst.

bp 94℃ (0.2 mml1 mm1l 12
10~139°Ocm-'1785cm-'2850-2960cm-'M" 539 Synthesis Example 4゜Pentadecafluorooctanoic acid sulfyl ester CH,
(CI+□) 3 (CIlzCtl=CH) z (
CH2) 80CO(CF2) bcFs prior synthesis example 1
By the same method as above, lylyl alcohol and pentadecafluorooctanoic acid were reacted in toluene with I)-1'luenesulfone hQ, w'A+ as a medium.

bp 135-139'C (0.2 mml 1 g) I
R1210 to 1380 cm-' 1780 cm-' 2850 to 3020 cm-'M' 663 Example 1 A polyethylene terephthalate film with a thickness of 4 μm was coated with CO by an oblique vapor deposition method, and rIIj and a thickness of 100
A ferromagnetic metal thin film was formed.

Next, on the surface of this ferromagnetic metal thin film, perfluoroalkylcarboxylic acid ester (synthesized in the previous synthesis example) and fatty acid amide (weight ratio 1:1) shown in Table 1 are diluted with a solvent (Freon). A sample tape was prepared by applying the 7 volumes of the solution at a coating amount of 10 μ/d and cutting it into a width of 172 inches.

(Hereinafter in the margin) Table 1 (Hereinafter in the margin) For each of the sample tapes produced, the dynamic friction coefficient and shuttle durability were measured under the conditions of temperature 25°C, relative humidity (RH) 50%, and -5°C. did. This dynamic friction coefficient was tested by using a guide bottle made of stainless steel (SUS304) and feeding it at a speed of 5 mm/sec under a constant tension. In addition, the shuttle running 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 Table 2.

(Hereinafter in the margin) Table 2 (Hereinafter in the margin) As is clear from this table, each of the examples of the present invention has a small dynamic friction coefficient under both room temperature and low temperature conditions, and is extremely stable in running. Even after running back and forth 100 times, no damage was observed on the tape surface. Furthermore, the 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, running was unstable, tape wear was observed, and durability was poor.

〔Effect of the invention〕

As is clear from the above explanation, in the present invention, perfluoroalkylcarboxylic acid ester and fatty acid amide are used as lubricants for the ferromagnetic metal thin film type magnetic recording medium, so that the coefficient of kinetic friction remains constant under any temperature conditions. can be made small, and a magnetic recording medium with excellent running stability and wear resistance can be obtained.

In particular, since the freezing point temperature of perfluoroalkyl carboxylic acid ester is low, the C effect is large when used at low temperatures.

Claims (1)

[Claims] A magnetic recording medium comprising: a ferromagnetic metal thin film formed on a nonmagnetic support; and a lubricant layer containing a perfluoroalkyl carboxylic acid ester and a fatty acid amide applied to the ferromagnetic metal thin film.