JPS60201522A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain the titled recording medium having lubricity, abrasion resistance, and traveling stability even at high temp. and humidity and to improve a decrease in the quality of images during still action by providing a lubricant layer contg. silane modified with an alkyl group and fatty ester on the surface of a ferromagnetic metallic thin film consisting of Co-Ni contg. oxygen and constituted on a nonmagnetic supporting body. CONSTITUTION:A lubricant layer 3 contg. silane modified with an alkyl group and fatty ester is arranged on the surface of a ferromagnetic metallic thin film 2 consisting of Co-Ni contg. oxygen and constituted on the surface of a nonmagnetic supporting body 1. The amt. W to be laminated of the modified silane is selectively regulated to 10X10<-8>-100X10<-8>g/cm<2> to improve the corrosion resistance, traveling property, and still action. At <=10X10<-8>g/cm<2>, the effects on lubricity and abrasion resistance can not be recognized. And at >=100X10<-8>g/ cm<2>, the traveling becomes unstable with an increase in frequencies of traveling. In addition, the output from a reproducing head during still action is decreased, and the quality of images is worsened.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to magnetic recording devices such as audio tape decks, video tape recorders, and PGM recorders, edge data processing devices such as computers, personal computers, etc. The present invention relates to a magnetic recording medium, particularly a magnetic recording medium in which a magnetic layer is composed of a ferromagnetic metal thin film.

Structure of conventional example and its problems Conventional) r-Fe2 o, , Go Gold-containing γ-Fe2O
3.A ferromagnetic metal thin film formed by a method such as plating, sputtering, vacuum evaporation, or ion blating, instead of a so-called coated magnetic recording medium in which ferromagnetic powder of cro2 is dispersed in an organic binder and applied. has been studied as a high-density magnetic recording medium, and has already been put into practical use for audio.

A major problem with magnetic recording media made of ferromagnetic metal thin films is wear and running stability. Especially in high temperature and high humidity conditions, magnetic recording media are subjected to high-speed relative motion with the magnetic head during the process of recording and reproducing magnetic signals, so they run smoothly and stably. must be left in a safe condition.

Further, wear and damage due to contact with the magnetic head must not occur. However, no ferromagnetic metal layer alone can withstand the harsh conditions of the magnetic recording and reproducing process.
Therefore, in the past, various lubricant layers have been provided on the surface layer.

Conventionally, a method for forming a uniform adsorption film of saturated fatty acids and metal salts using the Langmuir-Blodgett method has been disclosed in Japanese Patent Publication No. 80609/1983. Abrasion resistance is somewhat improved under normal conditions, but under high temperature and high humidity conditions (for example,
℃, 90% RH) regarding slipperiness and running durability.
There are still problems. Furthermore, when used as a magnetic recording medium for a video recorder, there is a phenomenon in which the output from the reproducing magnetic head decreases over time during still operation, that is, the image quality deteriorates.

Purpose of the Invention The present invention eliminates the above-mentioned drawbacks and provides smoothness and abrasion resistance even at room temperature and humidity.

An object of the present invention is to provide a magnetic recording medium that has running stability and also improves image quality deterioration during still operation.

Structure of the Invention The magnetic recording medium of the present invention comprises a non-magnetic support and a Co--Ni film containing oxygen on the surface of the non-magnetic support.
It is equipped with a ferromagnetic metal thin film consisting of a ferromagnetic metal thin film, and a lubricant layer containing a silane modified with an alkyl group and a fatty acid ester on the surface of this ferromagnetic metal thin film. sex.

It has running stability and can improve image quality deterioration during still operation.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a magnetic recording medium according to the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the basic configuration of a magnetic recording medium in an embodiment of the present invention.

In FIG. 1, 1 is a non-magnetic support formed on the surface of this non-magnetic support 1, and 2 is a ferromagnetic metal thin film made of a C0-Ni system containing oxygen, formed on the surface of this ferromagnetic metal thin film. 3 in the figure indicates a lubricant layer containing a silane modified with an alkyl group and a fatty acid ester.

A typical general formula of the silane modified with an alkyl group and a fatty acid ester (hereinafter referred to as modified silane) used in the present invention is shown as follows.

(CnH2n++ )p (cmHzm+1coo)q
5i(OR)4p-(1 where n, m are positive integers, p
H1 and 2. q is 1 and 2. OR is an alkoxy group, OCH3゜OC2H5,0G5H7, 0C4Hp,
It is selected from 0C5H, 1, etc.

It is preferable that n and m are 7 or more. If it is 6 or less, it will show smooth running immediately after starting to run within the specified running system, but as the number of runs increases, the running layer amount W will become smaller in terms of both wear resistance and runnability under normal temperature and normal humidity. If this lamination amount W is selected, 5X10f/crA ~ 500X10f
/cr& Teal Kotoka no Somashii. Note that, assuming that the specific gravity of the modified silane is approximately 1, the above value corresponds to an average film thickness τ of 5 to 500 [in].

Below 5×10 f/crl, no effect on lubricity is observed. If it is 500×10 f/d or more, the vehicle will run smoothly immediately after it is used, but as the number of runs increases, the running will become unstable.

We are currently investigating the cause of this, but as the ratio of modified silane to the surface of the ferromagnetic metal thin film increases, it can actually damage the running system (e.g. cylinders, posts, etc.)
This seems to be related to the phenomenon in which the adhesion between the two becomes better and the two become tight. If the laminated amount W of modified silane is selected from the viewpoint of improving wear resistance, running performance, and methyl action under high temperature and high humidity conditions, it should be 10 Xl 0 f/cr! L ~100X
10 r10+! It is desirable that it be. 10X10
Below t/Cd, no effect on lubricity or anti-wear effect is observed.

In addition, when it is 100 Xl 0 976.1 or more, it shows smooth running immediately after starting to use it, but as the number of runs increases, the running becomes unstable. Furthermore, during still operation, the output from the reproducing head decreases, deteriorating the image quality. In addition, from the viewpoint of electromagnetic conversion characteristics and so-called spacing loss, the amount of lamination W is selected depending on the wavelength used.

The ferromagnetic metal thin film used in the present invention is produced by evaporating a G O-N i-based alloy in a state where the incident angle changes continuously (referred to as continuous incident angle change evaporation) in an atmosphere dominated by oxygen gas. Preferably, the C0-N1 based ferromagnetic metal thin film containing oxygen is prepared.

The reason for this will be explained using FIG. 2. FIG. 2 shows an enlarged view of the ferromagnetic metal thin film 2 in FIG. . Incidentally, the surface 22 of the particle 21d having a columnar structure is covered with oxygen, and the oxidation degree including oxygen is particularly high at the top part 22a of this particle (also called the surface of the ferromagnetic metal thin film). Compounds with high valence are likely to be produced, and one of them includes 0oOOH, which corresponds to the trivalence of CO. Note that Co0OH is thought to be generated by reacting with H2O, which is a typical residual gas atmosphere in a vacuum evaporation apparatus.

Moreover, this Co00H reacts with the alkoxy group OR in the modified silane and undergoes hydrolysis, resulting in 1-mainly -0JcO
A strong bond is created.

Therefore, an oxygen-containing C0-Ni ferromagnetic metal thin film created by evaporating a Q,-Ni alloy in an oxygen-dominated atmosphere with a continuously changing incident angle has a trivalent This ferromagnetic metal thin film is a good material when forming modified silane on the surface of this ferromagnetic metal thin film. It can be said that it is a ferromagnetic metal thin film with a surface.

The nonmagnetic support used in the present invention is polyethylene terephthalate or a copolymer or mixture thereof.

A polyester film made of polyethylene naphthalate or a copolymer or mixture thereof, a polyimide film such as polyesterimide, polyimide, etc.

A typical example is a plastic film made of aromatic polyamide film or the like.

Alternatively, it may be an inorganic material such as glass, alumina, ceramics, sapphire, or aluminum.

The lubricant layer of the present invention is prepared by dissolving the modified silane in a solvent and applying a wet method such as a road coating method, an air knife method, a gravure method, a reverse roll method, a doctor knife method, etc. to the surface of the ferromagnetic thin film. It is formed by applying it to

Solvents used in the coating solution include Hensen, toluene, and xylene.

Any solvent can be used, such as isopropyl alcohol. In addition to the above-mentioned wet method, other methods for forming the lubricant layer include vapor deposition and plasma polymerization, in which the lubricant is formed directly on the surface of the ferromagnetic metal thin film in vacuum without using a solvent. There is a dry method consisting of nine ion brating etc.

A more specific embodiment of the present invention will be described below.

(Example-1) Vacuum device using a long and wide smooth polyethylene terephthalate biaxially stretched film as a non-magnetic support to significantly suppress protrusions caused by residual polymerization catalyst and reduce surface roughness to 308 or less The surface of this non-magnetic support is deposited on the surface of the non-magnetic support by continuously varying the incident angle in an atmosphere dominated by oxygen gas.
o -Ni alloy (Ni: 20 wt%) is evaporated,
A ferromagnetic metal thin film made of a Go-Ni system containing oxygen was laminated. The thickness of this ferromagnetic metal thin film at this time is 1500 mm.
It was eight.

Next, in the above vacuum apparatus, by vacuum evaporation method,
That is, modified silane (C17H5s) filled in the evaporation source
) (C15H51Coo )81 (0()13)2
By heating to a predetermined temperature If K and evaporating it,
It was laminated on the ferromagnetic thin film.

The amount of lamination of this modified silane at this time is 2×108°5
X10, 10X10, 50X10, 100
X10.

200X10, 500X10, 1000X10
[It was level 8 of V7afJ.

Note that the amount of lamination is mainly controlled by the temperature inside the evaporation source container filled with the above-mentioned modified silane.

Furthermore, in order to find out the amount of this modified silane that is actually adhered, we use a microbalance to measure it using a gravimetric method, but it generally agrees with the amount of lamination W calculated using a film thickness monitor. , we have confirmed that Thereafter, the long and wide magnetic recording medium was cut into 8 pieces of width to obtain magnetic tapes with sample reservoirs of 1.2 degrees, 3.4 degrees, 5 degrees, 6 degrees, and 7.8 degrees.

The coefficient of kinetic friction of the magnetic tape with a lubricant layer provided in this way and the magnetic tape without a lubricant layer (the sample, the cane is set to 0) is 3.
The measurement was carried out in a room at 0°C and 904RH.

We prototyped a deck with essentially the same functions as a commercially available VH3 video recorder, set it to still mode,
How the output from the reproducing head changes over time was investigated under an environment of 30°C and 901H.

(Example-2) Modified silane (C+3H27) (C+yH35Co
o) 2Si (OCH3) was deposited by vacuum evaporation.

Thereafter, the long and wide magnetic recording medium was
I cut it to 11111. The stacking amount W of modified silane at the time of preparation was 8 levels as in Example-1, but the relationship between the stacking amount W and the evaluation results and effects described below is the same as that in Example-1. Since it is generally consistent with
In Example-2, the stacking amount W is small. The sample of this magnetic tape is indicated by 9.

Thereafter, the measurements shown in (Example-1) were performed in the same manner.

(Example-3) Using a ferromagnetic metal thin film prepared in the same manner as in Example-1, coating liquid I having the following composition was applied to the surface of the ferromagnetic metal thin film by a road coating method. Coated.

Thereafter, the magnetic tape was cut into pieces of 8πm, and the K of the magnetic tape was indicated as 10. The amount of stacked layers at this time was 75 x 10 (j'/cJ) when measured using a microbalance. The measurements shown in Example 1 were performed on this tape in the same manner.

Table 1 summarizes the results of the measurement of the coefficient of dynamic friction and the still measurement of the magnetic tape shown above.

The method for measuring the coefficient of dynamic friction will be explained.

A post with a diameter of 4φ and a material of 5US420J2 is installed, and a magnetic tape is wound around the post. A certain tension is applied to the magnetic tape, and it is fed at a speed of 15 mm and 7 seconds. .

Table 1 shows the coefficient of kinetic friction at the first and 100th reciprocation, among data representing the relationship between the number of reciprocations and the coefficient of kinetic friction when the magnetic tape is run 100 times. Furthermore, the presence or absence of unspecified scratches is 1.
This shows whether or not there were scratches on the surface of the ferromagnetic metal thin film of the magnetic tape after the magnetic tape was run back and forth 00 times.

Next, still measurement will be explained.

Two magnetic heads are mounted on the 40φ cylinder, and one magnetic head is used as a recording head to record a signal with a wavelength of 0.85 μm on the magnetic tape, and then the operation of the recording head is stopped. Then, using another magnetic head as a reproducing head, the state in which the output from this reproducing head changed over time was recorded on a recorder.

The still life shown in Table 1 is -6dB from the maximum output.
This shows the time it takes for the temperature to drop to the level of .

Table 1 Effects of the Invention Modified silane (CnH2n
+ 1 )p (CmHzm+1 coo )q Si
The magnetic recording medium of the present invention equipped with a lubricant layer containing (OR)4p-4 exhibits a low initial J value (approximately 0.3) of the dynamic friction coefficient at high temperature and high humidity, and a low value of 1100
It can be seen that the value "after the first round trip" has less fluctuation than the "initial" value, that is, the stability of the dynamic friction coefficient indicates that the vehicle has running stability. Furthermore, it can be seen that the wear resistance is improved as there are no scratches on the surface of the ferromagnetic metal thin film made of the co-Ni system containing oxygen.

Furthermore, it can be seen that the magnetic recording medium of the present invention has a still life span of nearly 50 minutes under high temperature and high humidity conditions, that is, the still characteristics have been significantly improved.

In the above embodiments, a magnetic tape was used as an example of the magnetic recording medium, but it may also take the form of a magnetic disk, a magnetic sheet, etc. without departing from the gist of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the basic configuration of a magnetic recording medium according to the present invention, and FIG. 2 is a diagram showing the basic structure of a magnetic recording medium according to the present invention, and FIG.
FIG. 2 is an enlarged view of a portion of a ferromagnetic metal thin film made of a ferromagnetic metal thin film. 1...Nonmagnetic support, 2...Ferromagnetic metal thin film consisting of o-Ni system containing oxygen, 3...
...Lubricant layer containing modified silane.

Claims (1)

[Claims] a non-magnetic support; and a surface of the non-magnetic support,
Moreover, it is characterized by comprising a ferromagnetic metal thin film made of a Q(, -Ni) system containing oxygen, and a lubricant layer containing a lubricant modified with an alkyl group and a fatty acid ester on the surface of the ferromagnetic metal thin film. magnetic recording media.