JPS5971131A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a recording magnetic medium having excellent running property and durability in addition to corrosion resistance by forming a lubricant having the specific HLB value which indicates a hydrophilic-lipophilic balance on a thin ferromagnetic metallic film contg. oxygen formed on a non-magnetic substrate. CONSTITUTION:A thin ferromagnetic metallic film contg. oxygen is formed on a nonmagnetic substrate, and a lubricant having <=4 HLB (hydrophilic-lipophilic balance) value is provided on the thin metallic film. A lubricant having <=4HLV value, for example, ester such as fatty acid ester and polyhydric alcohol ester, fatty acid amide, higher alcohol or higher amine is coated alone or a mixture prepd. by mixing the lubricant having <=4HLB value and the lubricant having 4-30HLB value so as to have <=4HLB value as a whole after the mixing, for example, a stearic acid-tristearin mixture is used as the lubricant having <=4 HLB value.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a ferromagnetic metal thin film magnetic recording medium with improved running stability and durability.

Conventional structure and its problems A metal thin film made of iron, cobalt, nickel, or an alloy containing these as main components, or a metal thin film containing oxygen in these is vacuum evaporated or sputtered.

Polyester 2 is produced using vacuum film forming methods such as ion blating.
ferromagnetic metal thin film magnetic recording media formed on substrates made of polymer films such as stell film, polyimide film, non-magnetic metal thin plates, etc. have dramatically higher recording density than conventional coated magnetic recording media. However, in order to achieve this high density, it is necessary to reduce the gap of the magnetic head and smooth the surface of the magnetic recording medium to reduce spacing loss as much as possible. be. A specific spacing value of 5008 or less, more preferably 3008 or less is required. Although head touch and running performance can be considerably improved by finely controlling the surface shape of the magnetic recording medium, it is essentially difficult to significantly reduce the contact area between the head and the medium, and the coefficient of friction is The tendency for it to grow is unavoidable.

Additionally, ferromagnetic metals are generally prone to corrosion in high humidity, and to avoid this, alloying of the magnetic layer is required.

In addition to improvements such as oxygen content, the application of rust preventives has been proposed. Rust inhibitors are usually compounds that have a specific polar group that binds to ferromagnetic metal ions, and prevent rust by being adsorbed onto a ferromagnetic thin film.
It has become clear that it has little effect on improving head richness and running performance, and that excessive adhesion can cause head clogging.

On the other hand, the application of various lubricants has been proposed for the purpose of lowering the coefficient of friction between the head and the magnetic recording medium, but unless special types are excluded, these lubricants do not show any rust-preventing effect and sometimes act as corrosion accelerators. It has become clear that there are cases.

OBJECTS OF THE INVENTION An object of the present invention is to easily obtain a magnetic recording medium that has corrosion resistance, excellent runnability, and durability.

Structure of the Invention The present invention is based on an oxygen-containing ferromagnetic metal thin film formed on a non-magnetic substrate, which has an HLB value of 4, which represents the hydrophilic-oleophilic balance.
The following lubricants are provided.

Description of Examples The non-magnetic small substrate is generally a polyester film,
Plastic films such as polyamide films and polyimide films, metal plates such as aluminum plates and stainless steel plates, and inorganic plates such as glass plates and ceramic plates are used.

The ferromagnetic metal thin film layer includes iron, cobalt, nickel,
Metals containing these materials as main components are directly deposited onto the substrate by vacuum evaporation, ion blasting, sputtering, etc.
Or aluminum.

A thin film formed through a non-magnetic base thin film of titanium, chromium, etc., and a thin film formed by inserting the above-mentioned non-magnetic thin film as an intermediate separator between ferromagnetic thin films can be used. In particular, it is desirable that the ferromagnetic thin film and the underlying thin film contain oxygen to improve adhesion strength with the substrate, corrosion resistance, and magnetic properties.

Regarding the latter, see Japanese Patent Publication No. 56-23208.

JP-A-53-42010, JP-A-56-1501
No. 4, Japanese Patent Application Laid-Open No. 57-37719, etc.

Rust preventive adsorbents to be formed on ferromagnetic metal thin films can be broadly categorized as follows: For ferromagnetic metal thin films that do not particularly contain oxygen, rust preventives used for general metals can be used. Examples of these include alkylamines, basic nitrogen compounds such as fatty acid salts of alkylamines, phosphorus compounds such as alkyl phosphates, alkyl thiophosphates, alkylhydrogen biophosphates and phosphites, sulfonates, mahogany acids, etc. Sulfonates, sulfonates such as dinonylnaphthalene sulfonate, sorbitan monooleate, specific esters such as methyl esters of organic acids, etc.9 Metallic soaps of petroleum acid and abietic acid,
There are specific carboxylic acid derivatives such as mercaptostearic acid, and also dicyclohexyl ammonium nitrite.

So-called volatile rust inhibitors such as diisopropylammonium nitrite and cyclohexylamine carbamate can also be used. For examples of these, see 1417-1439 of "Metal Surface Technology Handbook" New Edition, Metal Surface Technology Handbook Edition (published in 1963, 2 publishers, 'B Kogyo Shimbunsha).
stated on the page.

Furthermore, the rust preventives used for general metals are not necessarily suitable for ferromagnetic metal thin films containing oxygen, and in fact, applying these preventives actually accelerates corrosion. Therefore, it is important to use a rust preventive agent that is compatible with ferromagnetic thin films containing oxygen, in addition to known rust preventive agents. Anticorrosion agents suitable for this purpose include dihydric phenols.

There are diallyl ketones, alkylphenols, naphthols, quinones, nitroso compounds, oxime compounds 5, etc., and these are shown in more detail as follows.

Dihydric phenols include hydroquinone, resorcinol,
Pure phenols such as catechol, and their alkylamino, nitro, nitroso, and halogeno substituted products, such as 2-methylhydroquinone, 4-methylresorcinol, 5-methylresorcinol, 4-methylpyrocatechol, 2゜5- dimethylhydroquinone, 4,6
-dimethylresorcinol, 2,5-dimethylresorcinol, 2-isopropyl-5-methylhydroquinone, 2-tert-butylhydroquinone, 2,6-tert-butylhydroquinone, 4-tert-butylcatechol, 2-amylzo Rucinol.

It refers to 2-nitroresorcinol, 2.5-)chlorohydroquinone, and the like.

Diallyl ketones refer to benzophenone and derivatives thereof, such as benzophenone, 4-methylbenzophenone, 3-methylbenzophenone, 3,4-dimethylbenzophenone, 4,4'-dimethylbenzophenone, 3,4'-dimethylbenzophenone. , 4-
Noalkyl substituted products such as ethylbenzophenone, 4-hydroxybenzophenone, 4,4'-dihydroxybenzophenone, 2,3゜4-) IJ Hydrobenzophenone, 2,4-dihydroxybenzophenone, 2,2',6
, 6'-tetrahydrobenzophenone, 2,3', 4.
Hydroxybenzophenones such as 4'6-pentahydroxybenzophenone, aminobenzophenones such as 4-aminobenzophenone and 4'4'-diaminobenzophenone, or benzophenones having two or more types of substituents, such as 4-methoxy-2 -hydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,6-cyhydroxy-4-methoxybenzophenone, etc. Refers to alkyl phenols and alkyl-substituted phenols, such as 0-cresol, m-cresol, p-
Cresol, 0-ethylphenol, m-ethylphenol, p-ethylphenol, 2,3-dimethylphenol, 2,5-methylphenol, 2,6-dimethylphenol, 3,4-dimethylphenol, 3,6-
Dimethylphenol, 2,4.6-trimethylphenol, 2,4.5-trimethylphenol, 5-inpropyl-2-methylphenol, 2-isopropyl-6-
Methylphenol, p-tert-butylphenol,
2,6-tert-butyl-p-cresol, 4
, 4'methylenebis-2,6-di-tert-butylphenol, 2,6-dimethyl-4-tart-butylphenol, 2-tert-amyl-4-methylphenol, 2-methyl-4,6-di-tart-butylphenol, 2 , 4.6-) di-tert-butylphenol, etc.

Naphthols are α-naphthol, β-naphthol, 1
, 2-naphthalenediol, 1,4,5-naphthalenetriol, 1.2,5,8-naphthalenetetraol and other pure naphthols; nitro, nitroso, amines,
Halogeno-substituted naphthols + fr-toe Irf, 1
-Chloro-2-naphthol.

2.4-dichloro-1-naphthol, 1-nitro-2-
naphthol, 1,6-sinitro 2-naphthol, 1-
It refers to nitroso-2-naphthol, 2-nitroso-1-naphthol, 1-amino-2-naphthol, and the like.

Quinones include p-benzoquinone, ○-benzoquinone,
1,2-naphthoquinone, 1,4-naphthoquinone, 2,6
- Naphthoquinone, anthraquinone.

9-1 o-Phenanthrenequinone, unsubstituted quinone such as diphenoquinone, methyl-p-penzquinone, 2,
3-dimethyl-p-benzoquinone.

0 Methylquinones such as 2-methyl-1,4naphthoquinone and 2-methylanthraquinone, 2,5-dihydroxy-p
-benzoquinone, tetrahydroxy-p-benzoquinone, 5-hydroxy-1,4-naphthoquinone, 2,3-dihydroxy-1,4-naphthoquinone, 6,8-dihydroxy-1,4-naphthoquinone, 2-hydroxyanthraquinone.

1.2-dihydroxyanthraquinone, 1,2゜3-trihydroxyanthraquinone, 1,2.4-trihydroxyanthraquinone, 1,2.5-trihydroxyanthraquinone, 1.2.6-trihydroxyanthraquinone, 1,2 .7-) Hydroxyquinones such as dihydroxyanthraquinone 2, 2-amino-anthraquinone, 1
, aminoquinones such as 2-diaminoanthraquinone, 1
- Nitroquinones such as nitroanthraquinone and 1,5-dinitroanthraquinone, halogenoquinones such as 2,6-dichloro-p-benzoquinone, tetrachloro-p-benzoquinone, and tetrabromo-p-benzoquinone, or two or more substituents. 11 7;- quinones, such as 2,6-dichloro-3゜6-
It refers to dihydroxy-p-benzoquinone, 1-methyl-2-hydroxy-1,4-naphthoquinone, and the like.

A nitroso compound is an organic compound having both a hydroxyl group and a nitroso group, and includes nitrosophenol-based and nitrosonaphthol-based organic compounds. Specifically, 1
-Nitrone-2-naphthol.

2-nitro:/-1-1-phthol, 1-nitroso-2
-su7) -ru3, e-disulfonic acid disodium salt and troso R salt), 4-nitroso-2-methoxy-1-phenol, 4-nitroso-2-ethoxy-1-phenol, 4-nitroso compound ( Chlor, 6-nitroso-〇-cresol, 4-nitro:/-m-cresol 0-nitrosophenol.

2-nitrosoresorcin, 4-nitrosoresorcin, 2
- Nitrosoresorcin monomethyl ether.

N-nitron phenylhydroxylamine ammonium salt (cuperone), p-nitrosophe/-#)2-
=)o:/-1-naphthol-4-sulfonic acid, 5-nitrone-8-quinolinol, etc.

The oxime compound refers to benzyl oxime, glyoxime, benzaldoxime, benzamide oxime, α-benzoin oxime, acetophenone oxime, benzophenone oxime, dimethylcrioxime, salicylamide oxime, and the like.

The rust preventive content on the surface of the ferromagnetic metal thin film is 00oo1
A weight factor of 10 to 10, more preferably 0.001 to 0.1, is appropriate, and the inside of the ferromagnetic metal thin film may be equivalent to or less than that near the surface.

A lubricant layer formed on a ferromagnetic metal thin film or on a ferromagnetic metal thin film subjected to the above-mentioned rust prevention treatment is classified using the HLB value representing the hydrophilic-oleophilic balance as a scale. This HLBO value is said to be useful. A value calculated by HLB=10X (inorganic)/(organic) is used.

Here, inorganicity and organicity are values specific to each structure. Based on this HLB value, Table 1 shows the results of coating various lubricants on the ferromagnetic metal thin film.

Table 1 - HLB value of lubricant and swell of magnetic surface As is clear from the table above, 14 l-" lubricant with HLB value of 4 or less has no resistance even in high temperature and high humidity (6o"C, 9o%RH). There was no change between the magnetic substrate and the ferromagnetic metal thin film. On the other hand, lubricants with an HLB of 4 or higher are used at high temperatures and high humidity (e
o'c, 9o% RH)K When left for 4 days or more, the adhesion strength between the nonmagnetic substrate and the ferromagnetic metal thin film weakened, and small bulges of the metal thin film occurred. From the above results, lubricants with an HLB value of 4 or less, such as fatty acid esters, polyhydric alcohol esters, fatty acid amides, and higher alcohols, are recommended as lubricating materials for improving the running properties and durability of metal thin film magnetic tapes. , apply a higher amine etc. alone, or
Or a lubricant with an HLB value of 4 or less and a lubricant with an HLB value of 4 to 30.
It is preferable to use a lubricant mixture such as a trisearic acid stearate mixture such that the overall HLB value after mixing is 4 or less.

To form a lubricant layer on the surface of a ferromagnetic metal thin film, the above lubricant is diluted with a solvent and applied thinly to the ferromagnetic metal thin film, the vapor of the lubricant is applied to the surface, or the lubricant is placed on the back side of a non-magnetic substrate. This can be done by leaving it in place and transferring it to the surface of the metal thin film during winding. It is also possible to perform heat treatment after forming the lubricant layer in order to stabilize the lubricant layer. The thickness of the lubricant layer is preferably 500 Å or less, preferably 200 Å or less. When the ferromagnetic metal thin film has a columnar crystal structure formed by oblique evaporation, etc., a lubricant layer may be formed uniformly over the entire surface of the columnar crystal, or it may be deposited locally on the surface. .

Next, a more specific example will be explained.

A biaxially stretched polyester film substrate with a thickness of 121 tm and good surface properties was placed along the circumferential surface of the cylindrical can to form a 5X10-
” Oxygen gas at a vacuum level of T o r r, 317 m
CoNi alloy (Ni content 20 wt%) was introduced at a flow rate of 1n and melted by electron beam heating by continuous oblique evaporation (
Low incident angle component below 30°C cut).

In this way, an oxygen-containing C0Ni ferromagnetic thin film with a thickness of 1000 mm was formed on the film substrate. The surface of this ferromagnetic metal thin film was coated with the rust preventive agent shown in Table 2 dissolved in an appropriate solvent at a concentration of 0.001 to 0.1% by weight, and then the lubricant shown in Table 2 was also applied. . The lubricant has a concentration of 0
．． A lubricant layer was formed by dissolving 0.001 to 0.1% by weight in an appropriate solvent such as toluene or ethanol, coating and drying. These samples were then slit into predetermined widths to form magnetic tapes. The friction coefficient of the tape sample prepared as described above was investigated, and further
The sample was left in an atmosphere of %RH, and every three days it was taken out and recorded and played back using a video deck to check for clogging. The results are shown in Table 2.

As is clear from the results shown in the table above, the ferromagnetic metal thin film according to the present invention is coated with anti-corrosion treatment and is further coated with a lubricant, making it difficult for clogging to occur. Ta.

Note that this example was related to a CoNi-based magnetic thin film, but Co@4'l thin film, Fe-Ni magnetic thin film F
Similar effects were obtained with e-Co magnetic thin films and the like.

Effects of the Invention According to the present invention, it is possible to easily obtain a magnetic recording medium with excellent durability such as improved corrosion resistance and runnability, and prevention of head clogging, and its practical value is extremely large. .

Claims (1)

[Claims] (1) A ferromagnetic metal thin film containing oxygen is formed on a non-magnetic substrate, and a lubricant having an HLB (hydrophilic-oleophilic balance) value of 4 or less is provided on the metal thin film. magnetic recording medium. (Rumor) The magnetic recording medium according to claim 1, characterized in that a ferromagnetic metal thin film is subjected to rust prevention treatment.