JPS62103832A - 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 aliphat. amine 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 aliphat. amine 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 aliphat. amine is exemplified by the formula, where the hydrocarbon group shown by R1 is a satd. or unsatd. hydrocarbon group and may be the pertly substd. hydrocarbon group. The amt. of the lubricating agent to be coated is preferably 0.5-100mg/m<2>.

Description

[Detailed description of the invention] r 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. This invention relates to a so-called ferromagnetic metal GT film type magnetic recording medium.

[Summary of the invention]

The present invention provides a magnetic recording medium in which a ferromagnetic metal G1 film is formed as a magnetic layer on a non-magnetic support, in which a perfluoroalkyl carboxylic acid ester and an aliphatic amine are used as a lubricant in a 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.

[Conventional technology]

Conventionally, as a magnetic recording medium, r-
T-FezO3゜Fe containing FezO, Co
Fe*Oa,'r containing z Oa + C'
Powder magnetic materials such as ferromagnetic powders such as ferromagnetic powders such as ferromagnetic powders such as ferromagnetic powders such as ferromagnetic powders such as ferromagnetic powders such as ferromagnetic powders such as ferromagnetic powders such as ferromagnetic powders such as ferromagnetic powders such as ferrolide compounds containing F e 201 and Fe, O, etc. Coating-type magnetic recording media are widely used, which are made by coating and drying a magnetic paint containing vinyl chloride-vinyl acetate copolymer, polyester resin, polyurethane resin, etc. in an organic binder. .

On the other hand, with the increasing demand for high-density magnetic recording, ferromagnetic metal materials such as Co-Ni alloys are being developed using plating and vacuum 111/l forming techniques (vacuum mounting method, Suba, Tallinn 2, etc.).
1) A so-called strong (poor monovalent metal thin film type) magnetic recording medium has been proposed, which is directly deposited on a non-(f-dominant support such as a polyester film or polyimide film) by ion-propagation, ion-propagation, etc. This ferromagnetic metal thin film magnetic recording medium not only has excellent coercive force and squareness ratio, but also has excellent electromagnetic conversion characteristics at short wavelengths.
Since the thickness of the magnetic layer can be made extremely thin, the thickness loss during recording demagnetization and reproduction is extremely small, and there is no need to mix an organic binder, which is a non-magnetic material, into the magnetic layer, so Kl property + A' ! It has many advantages, such as being able to increase the packing density of No. 4.

However, in the above-mentioned ferromagnetic metal thin film type magnetic recording medium, since the surface smoothness of the magnetic layer is extremely good,
The actual contact area becomes larger, adhesion phenomena (so-called sticking) occur more easily, the coefficient of friction becomes larger, and there are many other drawbacks such as durability and running performance (improving these is a major issue). Generally, during the process of recording and reproducing magnetic signals, a magnetic recording medium is placed under high-speed relative motion with a magnetic head, and its movement is carried out smoothly and stably. In addition, it is better to minimize wear and scratches due to contact with Rui 1 Ki and Do.

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 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.

Furthermore, these adhesion and lubrication effects must be maintained 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 /lI! is widely used! The temperature range in which lubricants can be used is limited, and in particular, many lubricants become solid or freeze at low temperatures such as 0 to -5°C, making it impossible to fully demonstrate their lubricating effects.

Therefore, the present invention is! 20 The purpose of the present invention is 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 (H4).

[Means for Solving the Problems] As a result of intensive research, the present inventors determined that the above object could not be achieved by adding a long-chain alkyl group or a double bond to the ester moiety of perfluoroalkyl carboxylic acid. By combining a perfluoroalkylcarboxylic acid ester into which either a branched alkyl group or a branched alkyl group is introduced with an aliphatic amine, an improved lubricating effect is exhibited compared to when used alone. , at the same time as the operating temperature; The present invention is characterized in that a lubricant layer containing a perfluoroalkylcarboxylic acid ester and an aliphatic amine is applied to the ferromagnetic metal thin film.

The perfluoroalkyl carboxylic acid ester used in the present invention has the general formula % (wherein n represents an integer of 6 to IO, and R represents a hydrocarbon 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.
It is preferable that it is in the range of ~10. 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 group R 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, the aliphatic amine used in the present invention has the general formula: (indicates a group).

The hydrocarbon group represented by R1 in the above formula is a saturated or unsaturated hydrocarbon group, and may be a partially substituted hydrocarbon group. The above unsaturated hydrocarbon group is
Those having one or more double bonds are preferred, and the number of double bonds is preferably 1 to 4. Both of the above saturated or unsaturated hydrocarbon groups are straight chain hydrocarbons, but may have a monocyclic hydrocarbon in the straight chain or at the ends. moreover,
This end may be replaced with an aryl group and this aryl group may be bonded to N, or it may be a hydrocarbon group having an aryl group at the end. Upper device? Although the number of AM is not limited, suitable substituents include halogens such as chlorine, bromine, and fluorine, alkoxy groups, aryloxy groups (phenoxy groups), alkylcarbonyl groups, arylcarbonyl groups, alkylcarbonyloxy groups, and arylcarbonyl groups. An oxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acylamino group, a carbamoyl group, a sulfonamide group, a sulfamoyl group, etc. may be used alone or in combination with one or more of these groups.

Further, the hydrocarbon group represented by R, , R3 in the formula may be a saturated hydrocarbon group, an unsaturated hydrocarbon group, or an aryol group. These saturated and unsaturated hydrocarbon groups are
It may be substituted with the same substituent as in 3.

The blending ratio of the above-mentioned perfluoroalkyl carboxylic acid ester and aliphatic amine 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 aliphatic amine,
Conventionally known lubricants may be used in combination.

A method for attaching a lubricant layer containing these perfluoroalkyl carboxylic acid esters and aliphatic amines to a ferromagnetic metal thin film is to dissolve the above lubricant in a solvent and apply the resulting solution to the surface of the ferromagnetic metal thin film. The ferromagnetic metal thin film may be coated or sprayed, or conversely, the ferromagnetic metal thin film may be immersed in this solution and dried.

Here, the application amount is 0.5mg/m-100mg/
It is preferably M, and more preferably 1 .mu./M to 20 .mu./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.

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 be polyester such as polyethylene terephthalate,゛Polyethylene,
Polyolefins such as 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, and aluminum alloys. , light metals such as titanium alloys, and ceramics such as alumina glass.

The nonmagnetic support may be in any form such as a film, a notebook disk, a card, or a tram.

Further, the ferromagnetic metal thin film, which is the magnetic layer, is formed as a continuous film by a vacuum three-film formation 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 4 is irradiated by resistance heating, high frequency heating, electron beam heating, etc. under a vacuum of 101 to 10-1 Torr, and the ferromagnetic metal material (ferromagnetic metal material) is deposited on a disk substrate. -1
In order to obtain a high coercive force, a diagonal deposition method is adopted in which the above-mentioned strong metal material is evaporated diagonally on the substrate. Those who do this are also called.

The above-mentioned ion blating 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-N to IO-'Torr, and the above-mentioned ferromagnetic metal material is deposited during the discharge. It is evaporated.

The above sputtering method includes I O-' to l O-'To
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. There are sputtering methods, magnetron sputtering methods using magnetron discharge, and the like.

When this spackling is removed, Cr or W is used.

A base film such as V may be formed and then C may be placed.

In any of the above methods, the substrate is coated with Bi, Sb, Pb, Sn, Ga, and In.

By pre-depositing a base metal layer such as Cd, Ge, Si, T1, etc., and depositing the film in the direction perpendicular to the substrate surface, it is possible to achieve excellent in-plane isotropy without magnetic anisotropy orientation. 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 Ni, C.

-Ni alloy, Co-Pt alloy, Co-N1-p alloy,
Fe-Co alloy, Fe-Ni alloy, Fe-Co -N
i alloy, FC-Co-3 alloy, Co-N1-Fe-B alloy, Co-Cr alloy, or those containing metals such as Cr and A1. In particular, Co-Cr
When an alloy is used, a direct magnetization 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 aliphatic amine 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 lubricity even at low temperatures, and fatty amines exhibit good lubricity at room temperature, so the temperature range of use can be expanded.

[Examples] Specific examples of the present invention will be described below, but the present invention is not limited to these examples.

Synthesis Example 1゜Nonadecafluorodecanoic acid isostearyl ester Cl
1t (CHz) e-CH-C1l□-0CO-(CF
2) ucFi(CI+□)6CH3 An ester reaction was carried out between isostearyl alcohol and nonadecafluorodecanoic acid in toluene using p-toluenesulfonic acid as a catalyst. That is, after heating under reflux for 1 hour, 3
Moisture in the solvent was removed over time, toluene was removed under reduced pressure using an evaporator, and the 4i1
I made one. (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°C10, 2 mmtl
It was g.

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

The analysis was carried out by nuclear magnetic resonance analysis (NMR) and mass spectrometry (MASS). As a result, an absorption peculiar to the CF bond was observed from 121O to 1380cm-', an ester absorption at 1780cm-', and an absorption due to CH stretching vibration at 2910cm-'.In addition, in the mass spectrum obtained by the chemical ion method, the molecular ion beak M9 was found in 765, so this structure was determined.

Synthesis example 2, pentadecafluorodecanoic acid isostearyl estero:
CHs (CL) 5-CH-CHz-OCO-(CF
z) 4CF3(CHz)icHs By the same method as in Synthesis Example 1 above, isostearyl alcohol and pentadecafluorooctanoic acid were added in toluene.
The reaction was carried out using p-)luenesulfonic acid as a catalyst.

bp 120-134℃ (0.2mmHg) IR1
200-1400cm-'1780cm-'2920c+n'1M" 665 Synthesis Example 3゜Pentadecafluorooctanoic acid isononyl ester (C
Ilff) ,C(C11□)C11(CHI)C)1
2clI20cO(CFZ)acFi 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℃ (0.2mmHg) IR12
10-1390cm-'1785cm-'2850-2960cm-'M' 539 Synthesis Example 4゜Pentadecafluorooctanoic acid sulfyl ester CHz
(CHt)*(CHzCtoCH)t(Cllz)sOc
o(CFz)acFz By the same method as in Synthesis Example 1 above, rillyl alcohol and pentadecafluorooctanoic acid were reacted in toluene using p-)luenesulfonic acid as a catalyst.

bp 135-139℃ (0.2mm) Ig)IR
1210 to 1380 cm-' 1780 cm-' 2850 to 3020 cm-' M° 663 Example 1 Co was deposited on a polyethylene terephthalate film with a thickness of 4 μm by an oblique vapor deposition method to form a ferromagnetic metal thin film with a thickness of 100 G.

Next, on the surface of this ferromagnetic metal thin film, a solution of perfluoroalkyl carboxylic acid ester (synthesized in the previous synthesis example) shown in Table 1 and aliphatic amine diluted with a solvent (Freon) was applied in an amount of 10%. ■/m', apply 1
A sample tape was prepared by cutting the tape into a width of /2 inches.

(Below the margins) Table 1 (In Table 1, ph indicates a phenyl group.) (Below the margins) For each of the produced pull tapes, the temperature was 25°C.
The dynamic friction coefficient and settling durability were measured under the following conditions: 1 relative 12 degrees (Rt() 50%) and -5°C.The dynamic friction coefficient was 1, and the material was stainless steel (SUS304).
Apply a certain tension using the guide pin of 5 II
The test was carried out at a speed of Im/see. 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. Also, as a comparative example, a blank tape to which no lubricant was applied was also measured.

The results are shown in Table 2.

(Leaving space below) Table 2 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. No damage was observed on the tape surface after this. 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, perfluoroalkyl carboxylic acid ester and aliphatic amine are used as lubricants for ferromagnetic metal thin film type magnetic recording media, so that Also, the coefficient of dynamic friction can be reduced, 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, it is particularly effective 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 an aliphatic amine applied to the ferromagnetic metal thin film.