JPS62150518A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve magnetic characteristics and corrosion resistance by constituting a specific Co-Ni compsn. on a nonmagnetic substrate. CONSTITUTION:The magnetic layer consisting of Co, Ni, metal M1 or metal M1 and metal M2, rare earth element R and oxygen is formed on the nonmagnetic substrate. The metal M1 consists of >=1 kinds among B, Al, Si, P, Ge, Sn, Sb, Se, Te, Pb, and Bi, the metal M2 consists of >=1 kinds among Cu, Ti, V, Cr, Zr, Nb, Mo, W, and Ta, and the rare earth element R consists of >=1 kinds among Y, La, Ce, Pr, Nd, Sm, Gd, Tb, and Dy. The compsn. of the magnetic layer consists preferably, by weight, of 0-20% Ni, <=5% metal M1 or metal M1 and metal M2, 1-9% rare earth element R, 3-13% oxygen and balance Co. The thickness of the magnetic layer is preferably about 0.1-1.0mum. The recording medium having the excellent magnetic characteristics and corrosion resistance is thus obtd.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a magnetic recording medium, particularly a magnetic recording medium in which a Co-Ni metal film contains a specific rare earth element to improve magnetic properties and corrosion resistance. It is something.

[Conventional technology]

BACKGROUND ART Magnetic recording media have conventionally been used in which a kneaded product obtained by kneading magnetic powder such as r-FezO, Fe, etc. and a synthetic resin binder is coated on a non-magnetic substrate.

In contrast to this type of coating-type magnetic recording medium, a magnetic recording medium capable of high-density recording has been developed in which a metal magnetic thin film is formed on a substrate.

Methods for forming this metal thin film type magnetic recording medium include (chemical plating method as an Al wet method, sputtering method as a dry method, ion blating method,
Vacuum deposition methods are used.

In general, better magnetic recording media can be obtained by the dry method (compared to the wet method using Al) in terms of the base treatment applied to the substrate and the uniformity of the magnetic layer in the longitudinal and width directions. It is believed that.

However, the metal thin film magnetic recording medium formed by this dry process has extremely low thermodynamic stability compared to oxide magnetic powder, and has a structure with many pores, so it corrodes in the air and deteriorates in performance. Easy to invite.

Conventionally, attempts have been made to improve the corrosion resistance of magnetic recording media without reducing their magnetic properties. For example, in JP-A-56-15014, JP-A-57-196507, and JP-A-5B-134414, additive metals are added, a mixed gas of ozone and oxygen is directed to the magnetic layer forming part, or the number of oxygen atoms is It is disclosed that the corrosion resistance of a magnetic recording medium can be improved by quantitatively setting .

However, in all of these, although a slight improvement in corrosion resistance is observed, it is not sufficient, and in some cases, the saturation magnetization and residual magnetization may decrease, resulting in a decrease in the reproduction output of the magnetic recording medium.

[Problem that the invention seeks to solve]

This invention solves the drawbacks of the conventional magnetic recording media described above, and improves magnetic properties and corrosion resistance by adding a specific rare earth element to a Co-Ni metal thin film type magnetic recording medium. The purpose is to provide

[Means for solving problems]

In this invention, Co, Ni, and metal films are formed on a nonmagnetic substrate.

Alternatively, a magnetic layer consisting of metal H5, metal M2, rare earth element R, and oxygen is formed, and metal M1 is B, A 1 +S
i+P+Ge, Sn, sb, Se+ Te, p
b, one or more of Bi, metal M2 is Cu+ rt
, v, Cr, Zr, Nb, Mo, W, T
One or more of a, the rare earth element R is Y, La, Ce
+Pr, Nd.

This magnetic layer is composed of one or more of Sm, Gd, Tb, and Dy, and the composition is 0 to 20% Ni by weight, a metal film or metal M1 and 25% or less of metal M, and a rare earth element R1.
~9%, oxygen 3~13%, and the balance Co.

[Effect]

The present invention will be explained in more detail below.

First, the reason for limiting the composition of the magnetic layer formed on the nonmagnetic substrate will be explained.

Although Ni basically has a tendency to reduce the residual magnetization of a magnetic recording medium, it has the effect of improving the corrosion resistance of a magnetic layer made of a metal mainly composed of Co.

If the content exceeds 20% by weight, the residual magnetization of the magnetic layer will decrease significantly, resulting in a decrease in reproduction output.

B, AJ, St, P+ Ge, Sn, Sb,
Metal M1 consisting of one or more of S, e, Te+ pb, Bi is contained in order to stabilize the corrosion resistance of the magnetic layer, and Cu, Ti, V, Cr+Zr, Nb+
Metal M2 consisting of one or more of Mo, W + Ta
is contained to improve the corrosion resistance of the magnetic layer, but
When the content exceeds 5% by weight, residual magnetization decreases.

Y, La, Ce+ Pr+ Nd+ Sm, Gd
, Tb, and Dy are added in order to improve the magnetic properties and corrosion resistance of the Co--Ni metal magnetic layer. If it is less than 1% by weight, the corrosion resistance will not be improved sufficiently, while if it exceeds 1% by weight, the magnetic properties will deteriorate.

For the purpose of improving the coercive force of the magnetic recording medium, some oxygen combines with metal to form an oxide metal film, and the other part is absorbed into the magnetic layer of the magnetic recording medium and is contained within the magnetic recording medium. be done. If it is less than 3% by weight, the effect of adding oxygen will not be observed, the coercive force of the magnetic recording medium will not improve, and the corrosion resistance will deteriorate.

On the other hand, if the content exceeds ↓3% by weight, the influence of oxidation will be significant and the proportion of metal oxide will increase, making it impossible to obtain sufficient corrosion resistance and reducing the saturation magnetization Ms.

The thickness of the magnetic layer having the composition of the present invention as described above is preferably about 0.1 μm to 1.0 μm. If the thickness is less than 0.1 μm, sufficient reproduction output cannot be obtained, and if the thickness is less than 1. When OIIm is exceeded, the flexibility of the substrate decreases and it becomes difficult to increase the recording density.

Non-magnetic substrates on which such magnetic layers are formed include plastics such as polyester, acetate, polycarbonate, polyimide, etc. with a thickness of 5 to 25 μm, which have appropriate visibility and tensile properties and are heat resistant during vapor deposition. A glass substrate, a metal substrate such as Aj2, etc. are used as the substrate (film, disk-shaped base).

Next, a method for manufacturing the magnetic recording medium of the present invention will be explained. In this case, due to the demand for high-density recording, the formed magnetic layer must have a high coercive force and a high saturation magnetic flux density, so sputtering methods, ion blating methods, vacuum evaporation methods, etc. It is preferable to use a dry method.

In the dry method, in order to improve the coercive force, it is possible to improve the coercive force by injecting composition atoms obliquely into the substrate to form a thin metal film.
In this respect, it has a feature not found in coated types, in that a magnetic recording medium with a large coercive force can be obtained. When the constituent atoms are incident obliquely onto the substrate, an acicular thin metal film structure grows with the crystal orientation direction obliquely relative to the substrate. In such a state, crystal orientation and shape anisotropy cause magnetic anisotropy characteristics, and this increase in magnetic anisotropy improves the coercive force of the magnetic recording medium. Furthermore, the dry method has the advantages of excellent reproducibility of the magnetic properties of the magnetic layer and the ability to easily produce a magnetic layer that is uniform in the longitudinal and width directions.

In order to improve the adhesion with the magnetic layer, the nonmagnetic substrate is desirably subjected to a base treatment such as corona discharge treatment or primer treatment.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The magnetic recording medium of the present invention will be described in detail below with reference to the drawings and its manufacturing method.

FIG. 1 shows a cross-sectional configuration of a manufacturing apparatus of an embodiment of a magnetic recording medium of the present invention, in which a bell-shaped vacuum deposition tank 11
is formed. This vacuum evaporation tank 11 includes a vacuum pump 1.
2 is connected, and by driving the vacuum pump 12, the inside of the vacuum deposition tank 11 can be set to a predetermined degree of vacuum.

An electron beam evaporation source 14 is provided on the bottom plate 13 of the vacuum evaporation tank 11, and a ferromagnetic metal 1 is placed inside the electron beam evaporation source 14.
5 is placed. The ferromagnetic metal 15 is Co, Ni, B, AN, Si, P, Ge, Sn, Sb,
Se.

Metal shell or metal M1 made of one or more of Te, Pb, Bi and Cu, Ti, V, Cr, Zr
, Nb, Mo, and a metal M2 consisting of one or more of Ta and Y, La, and Ce.

It is made of a rare earth element R consisting of one or more of Pr, Nd, Sm, Gd+Tb, and Dy, and its composition ratio is set so as to give a predetermined film composition.

On the other hand, the barrier pull leak valve 17 from the oxygen cylinder 16
An introduction pipe 18 is led out through the bottom 13 , and the end of the introduction pipe 18 penetrates the bottom 13 and is inserted into the vacuum deposition tank 11 .

A delivery roll 21 and a take-up roll 22 are rotatably provided in the vacuum deposition tank 11, and these delivery rolls 2
A can 23 is rotatably provided between the winding roll 1 and the take-up roll 22.

A shutter 25 is provided between the electron beam evaporation source 14 and the can 23. This shutter 25 is rotatable and is opened only during film formation. The blocking piece 26 allows adjustment of the maximum incident angle θ2 and the minimum incident angle θ1 of the evaporated material to the substrate.

A non-magnetic substrate 30 is wound around the feed roll 21, and the end of the non-magnetic substrate 30 is pulled out, and the can 23
It is wound around the take-up roll 22 via. As the nonmagnetic substrate 30, a polyester film with a thickness of 12 μm was used.

The delivery roll 21 and the take-up roll 22 are driven,
For example, when the non-magnetic substrate 30 is in contact with the circumferential surface of the can 23,
It is transported at a speed of 15 m/n+im.

The vacuum pump 12 is driven to move the inside of the vacuum deposition tank 1
The ferromagnetic metal 15 in the electron beam evaporation source 14 is evaporated at a constant rate by evacuation to below 10-htorr. At the same time, the opening/closing cock 17 is opened to release oxygen gas from the introduction pipe 18 into the vacuum deposition tank 1-1. The supply of oxygen gas into the vacuum deposition tank 11 is also set so that the oxygen composition of the film becomes a predetermined one.

When the shutter 25 is opened, the ferromagnetic metal 15 emitted from the electron beam evaporation source 14 is obliquely incident on the non-magnetic substrate 30 within a predetermined angle range.
and reaches the non-magnetic substrate 30.

That is, the strong metal 1 emitted from the electron beam evaporation source 14
5, only those in the angle range from the minimum angle θ1 to the maximum angle θ2 with respect to the normal to the surface of the non-magnetic substrate 30 as shown in FIG. It is incident obliquely to the In this way, 0.
A magnetic bath with a thickness of 2 μm was formed.

The obtained magnetic recording media were cut and subjected to compositional analysis and evaluation of magnetic properties and corrosion resistance.

Compositional analysis used a combination of EPMA analysis and chemical analysis, and magnetic properties were measured using a sample vibrating magnetometer. and,
For evaluation of corrosion resistance, the magnetic recording medium to be measured is taken out from the constant temperature and humidity chamber after being maintained for a predetermined corrosion time T in a corrosion-resistant atmosphere (temperature 50 ° C., humidity 80%) created by a constant temperature and humidity chamber. This was done by irradiating this magnetic recording medium with a laser beam, measuring the amount of light transmitted through the magnetic recording medium, and determining its transmittance.

The results obtained are shown in FIG. 2, FIG. 3, and Table 1.

Figure 2 shows magnetic recording media with three types of compositions.
The horizontal axis shows the corrosion time T (hour) and the vertical axis shows the transmittance D (%), and the relationship between the two is shown. , remainder Co
The magnetic layer whose composition is indicated by a square mark is 14.6% by weight of Ni, 4.8% by weight of Sn as the metal M1, and the rare earth element R.
as LaO, 2% by weight, Ce0.6% by weight, Nd 1
．． The magnetic layer whose composition is 4% by weight of Ni, 4.6% by weight of oxygen, and the balance of CO is further indicated by a △ symbol.
Ge 1.0% by weight as 1, Nb 1 as metal M2
．． 5% by weight, Pr4.1% by weight as rare earth elements, Nd
It has a composition of 4.5% by weight, 4.9% by weight of oxygen, and the balance of Co.

In a magnetic recording medium that does not contain the rare earth element R, where the measurement point is indicated by O in Figure 2, the transmittance increases as the corrosion time T increases, and when the corrosion time exceeds 100 hours, the transmittance decreases. It increases to nearly 6%.

In the magnetic recording medium whose measurement points are indicated by M and △ in Figure 2, when the corrosion time T exceeds approximately 50 hours, the transmittance does not increase beyond a certain value of slightly over 3%, indicating excellent corrosion resistance. It is shown that These magnetic recording media correspond to the example shown in sample number 3.7 in Table 1, respectively.

The presence of the rare earth element R increases the corrosion resistance of the magnetic recording medium because the oxygen introduced into the vacuum-deposited layer 11 combines with the rare earth element R taken into the film by gettering action, and the rare earth element R is This is thought to be because an oxide film is formed and this oxide film covers the magnetic layer, thereby protecting the magnetic layer.

Figure 3 shows the relationship between the rare earth element R content ff1Rc and the coercive force Hc of the magnetic recording medium for magnetic recording media having two types of compositions.
12.6% by weight of i, 2.2% by weight of Si as metal,
As metal M2, Cr2.6wt%, oxygen 6.0wt%
, the remainder Co+Nd+Dy (the weight ratio of Nd and oy is 5:
3) The magnetic layer whose composition is also indicated by * is Ni5.8
Weight %, Ge 3.1 weight %, Oxygen 6.5 as metal M1
weight%, balance Co+Y+Pr (weight ratio of Y and Pr is 1
: It has the composition of 15.2).

As is clear from the measurement results in FIG. 3, when the content of the rare earth element R is increased beyond 9% by weight, the coercive force 11c of the magnetic recording medium decreases significantly.

The following can be seen from Table 1. That is, conventional example IVh
l is metal Ml+ in the thin film composition, metal M2 and rare earth element R are absent, comparative example N11I0.11 has oxygen, but the same t
lh12.13 is a rare earth element, and lh14 is a metal, and metal M2 is outside the composition range of the present invention, indicating that either or both of magnetic properties and corrosion resistance are inferior. However, Examples 2 to 9 show excellent magnetic properties and corrosion resistance.

〔Effect of the invention〕

As is clear from the above, the present invention is based on the conventional Co-N
It is possible to provide a magnetic recording medium with superior magnetic properties and corrosion resistance compared to i-based magnetic recording media.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the configuration of the main parts of a magnetic recording medium manufacturing apparatus according to the present invention, FIG. 2 is a diagram showing the corrosion resistance of magnetic recording media according to an embodiment of the present invention and a conventional example, and FIG. Various N
FIG. 3 is a diagram showing the relationship between the rare earth element content Rc and the obtained coercive force Hc in a magnetic recording medium of the following composition. 11: Vacuum deposition tank, 12: Vacuum pump, 14: Electron beam evaporation source, 15: Ferromagnetic metal, 16: Oxygen cylinder, 21
: Delivery roll, 22: Winding roll, 23: Can, 25: Shutter, 30: Nonmagnetic substrate.

Claims (2)

[Claims] (1) Formed on a non-magnetic substrate, the composition is Ni2 by weight.
0% or less, B, Al, Si, P, Ge, Sn, Sb, B
One or more of e, Te, Pb, Bi M_1 or M
_1 and Cu, Ti, V, Cr, Zr, Nb, Mo, W,
One or more of Ta, M_25% or less, Y, La, Ce
, Pr, Nd, Sm, Gd, Tb, and Dy in an amount of 1 to 9%, oxygen in an amount of 3 to 13%, and the balance being Co. (2) Formed on a non-magnetic substrate, with a composition of B and A by weight.
l, Si, P, Ge, Sn, Sb, Se, Te, Pb,
One or more of Bi M_1 or M_1 and Cu, Ti
, V, Cr, Zr, Nb, Mo, W, Ta or more M_25% or less, Y, La, Ce, Pr, Nd, S
1. A magnetic recording medium comprising 1 to 9% of one or more of m, Gd, Tb, and Dy, 3 to 13% of oxygen, and the balance of Co.