JPS5877028A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a titled medium having the uniform film thickness of a magnetic layer and having improved head touch, adhesion and magnetic characteristics, etc., by providing a ground layer consisting of a titanium alloy between a flexible substrate and a thin film magnetic layer. CONSTITUTION:After a ground layer consisting of a titanium alloy contg. >=1 kind among e.g. Al, Mn, V, Cr and Fe is provided on a flexible substrate such as a polymeric molded product by a sputtering method, etc. a thin film magnetic layer of Co-P and Co-Ni-P etc. is provided on the ground layer by vapor deposition, sputtering, ionic plating and plating methods.

Description

DETAILED DESCRIPTION OF THE INVENTION l BACKGROUND OF THE INVENTION A. Technical Field The present invention relates to magnetic recording media. More particularly, the present invention relates to a continuous thin film type magnetic recording medium in which the magnetic layer is a vapor phase deposited thin film such as a sputtered thin film of Co--P system or C0-N1-P system.

B. Prior Art In recent years, continuous thin film magnetic recording media in which the magnetic layer is a metal magnetic thin film have attracted attention.

There are various types of magnetic layers for such continuous thin film magnetic recording media.

Co-P or Co-Ni- as one of the magnetic layers
Taking a P-based thin film as an example, conventionally this thin film has the following characteristics:
Manufactured by plating method.

However, when these plating methods are used, the adhesion of the thin film to the substrate and the mechanical strength of the film are low, and sliding contact with the magnetic head causes wear and peeling of the thin film, resulting in changes in magnetic properties over time. It has the disadvantage of causing change. Another drawback is that the surface properties of the thin film are extremely poor, resulting in a drop in output, especially in high frequencies. Furthermore, alkali metal ions, acids, bases, etc. present in the plating bath may mix into the thin film, and these mixed impurities can cause the magnetic properties of the thin film to deteriorate over time, and in some cases, corrode the magnetic head. There are also some inconveniences. In addition, although the cause is not clear, especially when applied to audio tapes, the distortion of the third harmonic at 333 HzK is large, which poses a practical problem.

Considering the actual situation of VC@, the present inventors first developed Co.
We have proposed a magnetic recording medium in which a -P-based or Go-Ni=P-based thin film magnetic layer is formed by sputtering.

When the magnetic layer is formed by sputtering in this way,
It exhibits good magnetic properties, and the mechanical strength and adhesive strength of the thin magnetic layer are much higher than those obtained by plating, and its surface properties are also good. Changes in magnetic properties over time during storage are extremely small, and distortion to the third harmonic at 333 Hz is also extremely small.

However, magnetic recording media having such a sputtered thin film magnetic layer also have the following drawbacks.

First, the thickness of the sputtered thin film of the magnetic layer varies. This occurs even if the sputtering conditions are strictly maintained, and the
When sputtering is performed continuously on a long substrate, this variation can no longer be ignored and causes output fluctuations in tapes, etc.

Furthermore, as mentioned above, although the surface properties of the magnetic layer surface are improved, the surface properties are still not sufficient, resulting in poor head touch and low high-frequency output.

Furthermore, magnetic tapes using flexible substrates made of polymer moldings are unsatisfactory in terms of mechanical strength, especially residual elongation after application of a load.

Furthermore, the adhesion between the flexible substrate and the magnetic layer is not necessarily sufficient, and after many runs, the output is reduced, which is thought to be due to deterioration of the adhesion of the magnetic layer.

In addition, when the sputtered thin film is used as a magnetic layer, the B
) When measuring the I loop, two or more inflection points may appear on the demagnetization curve, etc., and two or more extremely thick values of the differential curve (dB/dH) K may appear. Such development occurs randomly during continuous sputtering, making it complicated to determine the appropriate bias for a medium such as tape.

Furthermore, it would be even more desirable if the coercive force were made even higher.

On the other hand, between such a magnetic layer and a flexible substrate,
It is believed that the various inconveniences mentioned above can be improved by forming a base layer such as a modern one.

According to experiments conducted by the present inventors, it has been found that, in fact, by forming a layer on a flexible substrate such as titanium, chromium, or aluminum, the above-mentioned characteristics to be improved can be improved. .

However, improvements in these characteristics are not necessarily sufficient;
When using the base layer of rutitanium, chromium, aluminum, and minilambu, which have favorable properties, K also has mechanical strength,
In particular, further improvements are desired in terms of residual elongation, adhesion, variation in film thickness, surface properties, deformation of BH loops, etc.

In addition, in the above, Co -P or Co -Ni -P
Although the explanation has been given using a sputtered thin film of the above-mentioned method as an example, it is desired to develop a new underlayer that further improves the above-mentioned properties for thin films of other compositions or thin films formed by isobaric evaporation.

■ Purpose of the Invention The present invention was developed in view of the above-mentioned circumstances. By using a new underlayer, the magnetic layer thickness is uniform, the held touch is good, and mechanical properties are improved. The main object of the present invention is to provide a magnetic recording medium that has high strength, good adhesion, and good magnetic properties, and overall has very good properties.

The present inventors have conducted extensive research in order to find a new underlayer composition that achieves these objectives, and have now accomplished the present invention.

That is, the present invention provides a magnetic recording medium having an underlayer on a flexible substrate and a thin magnetic layer on the underlayer, characterized in that the underlayer is formed of a titanium alloy. It is a recording medium.

■Specific structure of the invention The specific structure of the present invention will be explained in detail below.
The substrate used in the present invention is preferably non-magnetic and is preferably made of a flexible substrate, particularly a molded polymer such as polyester, polyimide, polyamide or the like.

In the present invention, a base layer made of a titanium alloy is provided on such a substrate.

In this case, various alloys containing titanium as a main component can be used as the titanium alloy.

Among these, A/ is particularly preferred.

At least one of Iori, V, Cr and Fe, preferably 4Qwt% or less, more preferably 0.1 to 4Q
Examples include books containing 1 to 30 wt%, more preferably 1 to 30 wt%.

Note that such a base layer usually has a thickness of about 50 to 5000A.

In addition, its formation methods include vacuum evaporation, sputtering,
Although various methods such as ion blasting and plating may be used, it is particularly preferable to use sputtering.

A magnetic layer is provided on such an underlayer.

The magnetic layer may have various compositions and may be formed by various vapor deposition methods such as evaporation, ion plating, and sputtering, but the effects of the present invention are said to be extremely significant. In this respect, a sputtered thin film is particularly preferred.

In this case, the sputtered thin film is Co-Ni based or Co
-Re-based and various other materials may be used. However, C0-P or Co-
Preferably, it is made of a Ni-P alloy.

And (C0100-X”X) 100-)/P)
When expressed as r, X, that is, Co/(Co+Ni,
) The weight ratio is preferably 0 to 35% by weight. This is because if X exceeds 35% by weight, the magnetic properties, particularly the coercive force Hc, will deteriorate. In this case, in terms of coercive force He, more preferable results are obtained if X is 0 to 30% by weight, particularly 0 to 28% by weight.

On the other hand, y, that is, the P content, is preferably greater than 0 and less than or equal to 6% by weight.・If it exceeds 6% by weight,
After all, the magnetic properties, especially the coercive force Hc, deteriorate.
In this case, in terms of coercive force Hc, preferable results are obtained if y is 1 to 6% by weight, more preferably 1.5 to 5.5% by weight.

In addition, in the above-mentioned composition, in the thin film, as a fourth component, for example, one or more other transition metal elements other than CO1Ni, such as Fe%Cr, Mn, Mo, etc., account for the total amount. It may be contained in a range of 10% by weight or less.

There is no particular restriction on the thickness of such a thin magnetic layer, and it depends on whether the magnetic recording medium performs analog recording or not.
The thickness may vary depending on whether it is used for digital recording or what kind of use it is used for.However, it is usually made into a flexible film as a continuous thin film with a thickness of about 500A to several micrometers. It is formed on a substrate.

In the most preferred embodiment, the magnetic layer thin film according to the present invention is formed on the above-mentioned substrate by sputtering.

The sputtering used may be so-called RF sputtering or so-called DC sputtering,
The device configuration may be either 2-pole, 4-pole, etc.
Furthermore, so-called magnetron sputtering may be used, and in some cases, so-called reactive sputtering, which is performed while flowing P or the like, may also be used.

The target to be used is usually a Co-Ni-P sintered body having the above composition.On the other hand, an ion source for bombarded ions is usually an Ar,
An inert gas such as Kr or Xe may be used. And, during operation, these inert dregs are 2X10-
It is preferable to maintain the pressure at 2 Torr or higher. This is because if the pressure is less than this, the magnetic properties of the obtained thin film, the coercive force Hc, will decrease. On the other hand, if the operating pressure is increased, the batter rate will decrease. Therefore, the operating pressure is generally 5 x 10
It is preferable to set it to approximately 2XIQ Torr.

Note that there are no particular restrictions on the plate voltage, plate current, gap between electrodes, etc., and these can be set to arbitrary values depending on the conditions.

Note that a protective layer is provided on the magnetic layer thin film thus formed, if necessary.

The magnetic recording medium of the present invention is useful as various magnetic tapes, magnetic disks, magnetic drums, magnetic sheets, magnetic cards, magnetic scales, etc. for performing analog or digital magnetic recording. Suitable as tape.

(2) Specific Effects of the Invention According to the present invention, variations in the thickness of the magnetic layer are extremely small, and fluctuations in the output of the tape, etc. are extremely small.

In addition, the surface properties of the magnetic layer are good, the head touch is improved, and the high-frequency output is high.

Furthermore, the residual elongation after loading is small and the mechanical strength of the tape is high.

Furthermore, the amount of residual adhesion of the magnetic layer is extremely high.

In addition, two or more inflection points rarely occur on the demagnetization curve of the BH loop, and the coercive force is high.

In this case, compared to the case where a base layer made of other metals or alloys is used, the medium of the present invention exhibits very little adhesive deterioration due to running and residual elongation.

When forming the magnetic layer from a sputtered thin film,
In addition to the above-mentioned improvements in adhesion and residual elongation, the deformation of the BH loops is also significantly improved compared to when a base layer made of other metals or alloys is used.

Furthermore, the sputtered thin film is made of Co-P or Co-Ni.
- When K is made of P-based material, these adhesive properties, mechanical strength, and occurrence of BH loose deformation are significantly improved.Furthermore, the film thickness is made uniform, and the output fluctuation is extremely small. In addition, the surface properties become better and the high-frequency output becomes significantly higher.

■ Experimental Examples The present inventors conducted various experiments to confirm the effects of the present invention. An example is shown below.

Experimental Example 1 Fifteen types of continuous long polyethylene terephthalate films each having a thickness of 9 μm were prepared as flexible substrates.

Among these 15 types of substrates, one substrate did not form any base layer, and the remaining three substrates were prepared with 'ri -5wt% At-awt, respectively, according to the trap of the present invention, as shown in Table 1.
%Mn, Ti-5wt%At-2wt%Cr-
1 wt% Fe, and 'rt-13 wt% V-11
A base layer made of wt%Cr-3wt%At was formed.

Furthermore, for comparison, the remaining one species has 'f'i, At, Cu, and S, respectively, as shown in ^1.
n, At, MO, Zn, Ni, Cr, Cu
A base layer made of -Be alloy and 5US304 was formed.

Each base layer was formed by DC sputtering.

In this case, a corresponding metal or alloy is used as the target, plate voltage is 2 KV, input power is 1.8 W/,
, i, argon was used as the bombarding ion, and the operating argon pressure was maintained at 7×10 −2 Torr.
The substrate was run continuously, and the thickness of each base layer was 10
It was set to 0OA.

Next, these 15 types of base films K.

A Go-Ni-P magnetic layer was formed. The magnetic layer was also formed by DC sputtering.

In this case, the target is 7 (CoQ8BNiQ
16) We used a sintered body prepared to have a composition of P. Further, as in the underlayer, the plate voltage was 2 KV, the input voltage was 1.8 W/m, and the operating argon pressure was 7 x 10''rorr.

The 15 types of substrates on which the base layer was formed as described above were run continuously, and a 3500A thick Co
A -Ni-P thin film magnetic layer was formed.

Next, each of these was slit into 3.81-width pieces,
A C-120 cassette tape was prepared according to a conventional method. Various characteristics of the 15-sized medium thus formed were evaluated. The measured coercive force He of each medium is shown in Table IK below.

Next, each of these media tapes t, $K)iz, od13
After recording the signal, the tape speed for playback is 4.76.
m/sec), C-120 chibuteno output change.

The dynamic range (VU) was measured to evaluate the magnitude of output fluctuation mainly caused by variations in the thickness of the magnetic layer. The results are shown in Table 1.

In addition, 14 KHz MOL was measured mainly to evaluate head touch caused by surface characteristics.
The results are shown in Table 1.

Next, in order to evaluate the tape strength, each medium was cut into 1 m squares, one end of which was fixed and hung, and a 200 t tape was placed on the other end.
A load was applied for 1 minute, and the elongation thereafter was measured. The residual elongation (tX%) measured in this manner is shown in Table 1.

Separately, in order to evaluate the adhesion of the magnetic layer, after recording on each medium cassette tape, the temperature was 25°C and the relative humidity was 6°C.
At 0%, running at 4.76 cm/see was performed 500 times, and then playback was performed to measure how many times the level decreased by 5 dB or less. The results are shown in Table 1.

In addition, apart from this, one volume of C-120 tape ($17
m), 90 locations were sampled every 2 m, the BH loop was measured, and the number of deformed locations where two or more inflection points appeared on the BH loose demagnetization curve was measured.
The results are shown in Table 1.

From the results shown in Table 1+, it is clear that the medium of the present invention, compared to the case where other underlayers are provided, is more effective during output fluctuations due to variations in coercive force and film thickness, and in head touch due to surface properties.
Furthermore, it can be seen that each property exhibits the best values in terms of residual elongation, adhesion, and occurrence of BH loose deformation.

In addition, for each of the above-mentioned media, a protective layer containing polyvinylidene chloride, acrylic ester, glycerin molybdenum, and nostearate was formed on the magnetic layer to a thickness of 0.3 μm. Almost the same results were obtained.

Experimental Example 2 Various media were used in exactly the same manner as in Experimental Example 1, except that the magnetic layer set, composition, and underlayer composition were changed as shown in Table 2 below.
It was produced and each characteristic in Experimental Example 1 was evaluated.

From the results shown in Table 1, the effects of the present invention are clear.

Agent: Bentori Riishi Yo Ii

Claims (1)

[Scope of Claim] A magnetic recording medium having an underlayer on a flexible substrate and a thin magnetic layer on the underlayer. A magnetic recording medium characterized in that the underlayer is made of a titanium alloy.