JPS63304423A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve corrosion resistance and wear resistance by incorporating elements of >=1 kinds among at least Al, Cr and Ti into the 1st layer of protective films and essentially consisting the 2nd layer of the protective layers of Ni. CONSTITUTION:A ferromagnetic metal consisting of Co-20N is formed to 1,500Angstrom on, for example, a polyester film having 9mum thickness by mounting said polyester film to a vacuum deposition device, heating the Co-20Ni to evaporate in 5X10<-5>Torr vacuum, directing gaseous oxygen simultaneously to the vapor flow of the Co-20Ni at 200ml/min ratio and diagonally depositing the vapor thereof by evaporation on the film at 500Angstrom /sec deposition rate. Al is again heated to evaporate in 5X10<-5>Torr vacuum to form the 1st protective layer consisting of Al on the ferromagnetic metallic layer, following which Ni is heated to evaporate to form the 2nd layer of the protective films consisting of the Ni thereon. The polyester film 1 is thereafter cut to a prescribed width and the ferromagnetic metallic layer 2, the 1st layer 3 of the protective films, and the 2nd layer of the protective films are successively formed on said polyester film to prepare a magnetic tape. Such magnetic recording medium has the excellent corrosion resistance to corrosive gases and wear resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to magnetic recording media, and more particularly to improvement of a protective film on a ferromagnetic metal layer.

[Prior Art] A magnetic recording medium in which a ferromagnetic metal layer is provided on a non-magnetic substrate-L is expected to be thinner and have high recording density characteristics, so development is urgently needed.

However, for example, when the ferromagnetic metal layer is made of an easily corroded material such as Co, there is a problem in that the ferromagnetic metal layer is exposed on the surface and is easily corroded. Conventionally, in order to solve this problem, this ferromagnetic metal layer 1- is made of Cr, Ti, AJ! (JP-A-51-47401, JP-A-58-26320)
．． JP-A-58-26323) has been proposed.

However, although it is recognized that the corrosion resistance in a high lQ high humidity atmosphere is improved only by forming these protective films, in a corrosive gas atmosphere such as sulfur dioxide gas, a ferromagnetic metal layer mainly composed of Co and a Cre T r.

AJ! The potential balance between the electrodes and fm'2 is disrupted, and local batteries are easily formed and corroded. Historically, it also had the disadvantage of lacking wear resistance.

[Problems to be Solved by the Invention] The purpose of the present invention is to solve the drawback of corrosion that the prior art had and to provide a magnetic recording medium that has excellent corrosion resistance and wear resistance. Let it be [I].

[Step F to solve the problem] As a result of intensive study by the present inventors, a first protective film layer was formed on the ferromagnetic metal layer [-, and a protective film was further formed on this first protective film layer -1-. By forming a second layer and keeping the potential balanced, it becomes difficult to form a local battery and corrosion is prevented.
−I found out that it can be done. .

The first layer of protective film is at least AJ! Excellent corrosion resistance can be obtained by using elements that easily passivate, such as , Cr, and Ti.

Furthermore, by forming the second layer of the protective film from a material containing Ni as a main component, Co1 or Ni can be formed.

Potential balance is maintained with the ferromagnetic metal layer mainly composed of Fe or the like, and formation of local batteries is suppressed.

Furthermore, it was confirmed that the second layer of the protective film containing Ni as a main component is also effective in improving wear resistance. Although the cause of this is not clear, it is thought to be due to Ni oxides formed on the surface.

Even if the second protective film layer is omitted and only a protective film such as AJII Cr+'ri is laminated on the magnetic layer, sufficient corrosion resistance cannot be obtained and wear resistance is lacking. When the second protective film layer mainly composed of Ni is used in combination with the first protective film layer made of Al, Cr, Ti, etc., the corrosion resistance is synergistically increased by 1i+Jl.

The thickness of the first layer of the protective film is desirably within the range of 25 to 500, and if it is thinner than 25, the corrosion resistance will be poor.

It is preferable that the thickness of the second layer of the one-flange protective film is 25 Å or more. If there are less than 25 people, the corrosion resistance will be poor and the wear resistance will not be improved.

The total thickness of the first and second protective film layers is 50 to 1000.
It is desirable that the number be within the range of 50 people; if it is less than 50 people, the desired effect will not be obtained, and if it is more than 50 people, the spacing will become too large and the electromagnetic conversion characteristics will deteriorate.

The ferromagnetic metal layer is deposited on the substrate 1-1 by conventional means such as vacuum evaporation, sputtering, ion blasting, or plating. It can also be formed by methods other than these.

Examples of materials for forming the ferromagnetic metal layer include Co and Fe.

In addition to N i 'F, these oxides or Co
-Ni, Co-Cr, Co-Pt, Co-Mn, Co-
Ni-Cr, Co-N1-P, Co-Fe.

Co-Fe-Cr+ Co-Ti+ Ni-Fe,
Alloys such as Ni-Mn, or oxides of these,
Any material that has been conventionally used as a material for forming a strong layer may be suitably used.

The protective film is deposited on the ferromagnetic metal layer by conventional means such as vacuum deposition, sputtering, ion blating, CVD, plating, or the like.

Materials for forming the second layer of the protective film include Ni alone, their oxides, Ni-Cr, N1-Al, Ni-
Alloys such as Ti, Ni-Fe+Ni-Mn, or oxides thereof are preferably used. Therefore, the term "containing Ni as a main component" used throughout this specification includes "a second protective film layer consisting only of Ni."

When the ferromagnetic metal and the protective film forming material are deposited on the substrate, they can be deposited directly to the east of the surface of the substrate, but they can also be deposited obliquely. Further, when forming the first layer of the protective film by direct vapor deposition of 1π, the corrosion resistance is improved by 1-6 by forming a dense film without a columnar grain structure.

In the case of oblique deposition, for example, the material for forming the first layer of the protective film is obliquely deposited in the direction opposite to the J direction of the inclination of the ferromagnetic metal, and the material for forming the first layer of the protective film is deposited obliquely in the direction opposite to the J direction of the inclination of the ferromagnetic metal.
The material for forming the second layer of the protective film can be deposited obliquely in the opposite direction to the layer.

By diagonally depositing each layer in alternate directions in this way,
Gaps created in the ferromagnetic metal layer due to the shadow effect during oblique deposition are sealed by the protective film forming material tilted in the opposite direction, thereby suppressing corrosion from the surface of the magnetic recording medium.

Alternatively, the ferromagnetic metal layer is formed by oblique evaporation, the first protective layer is formed by vertical evaporation, and the second protective layer is obliquely deposited with an angle opposite to that of the ferromagnetic metal layer. It can also be formed by This method also provides the effect of sealing the voids in the ferromagnetic metal layer.

In addition, as a substrate, plastic films such as polyester, polyimide, polyamide, polyvinyl, polycarbonate, etc., and Cut Znt Si, AJ! .

Composite films mixed with carbon fiber etc., non-magnetic films such as Cu and Zn, AJ! Any conventionally used materials such as plates and glass plates are preferably used. Protrusions may be provided on the surface of the base.

In this way, a ferromagnetic metal layer is formed on the base, a first protective film layer is formed on the ferromagnetic metal layer, and a second protective film layer is further formed on the first protective film layer. In the magnetic recording medium, the first layer of the protective film contains at least one element among Al, Cr, and Ti, and the second layer of the protective film contains N.
A magnetic recording medium on which a protective film containing i as a main component is formed has excellent corrosion resistance against corrosive gases such as sulfur dioxide gas and excellent wear resistance. However, when a lubricant layer is formed on this protective film, the protection The friction coefficient of the film surface is reduced, and wear resistance is further improved.

The lubricant used is an aliphatic lubricant.

Fluorine-based lubricants, silicone-based lubricants, hydrocarbon-based lubricants, and the like are all suitably used.

Aliphatic lubricants include lauric acid, myristic acid,
Fatty acids such as valmitic acid, stearic acid, and behenic acid; Fatty acid esters such as zinc stearate, cobalt stearate, -rl-butyl stearate, and octyl myristate; Stearyl alcohol, myristyl alcohol Luna (!"<7) IIIMB Group alcohols; chlorides such as trimethylstearylammonium chloride and stearoyl chloride; amines such as stearylamine, stearylamine acetate, and stearylamine hydrochloride; and the like.

As the fluorine-based lubricant, perfluoropolyether, perfluoroalkyl polyether, etc. are preferably used, and a specific example of a commercially available product is Daifluor #20 manufactured by Daikin. Dupont Krytx M,
Crytox H.

Examples include PIDAX AR and Fomblin Z manufactured by Montegisson.

Silicone oil is a silicone lubricant.

Examples include modified silicone oil. Examples of hydrocarbon lubricants include paraffin and wax.

The thickness of the lubricant layer formed using such a lubricant is
In order to fully demonstrate the lubrication effect, it is desirable to use 20 or more people. If it is thinner than 20, the lubricating effect cannot be obtained. However, if the total including the thickness of the protective film is larger than 1000 people, the spacing becomes too thick (too much) and the electromagnetic conversion characteristics deteriorate.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples. However, the scope of the present invention is not limited to the following examples.

Actual MtlL A polyester film with a thickness of 9 μm was attached to a vacuum evaporation apparatus, and C0-2O was deposited under a vacuum of 5 x 10-5 Torr.
Ni is heated and evaporated, and at the same time oxygen gas is evaporated at 200ml/m.
Directed to a vapor stream of Co-2ONi at a rate of 50
A film of Co-2ONi with a thickness of 150 mm was deposited obliquely at a deposition rate of 0 people/sec.
0 ferromagnetic metal layers were formed.

Then, Aλ was applied under a vacuum of +tG and 5X10-5 Torr.
was heated and evaporated, and the Co-
A first layer of a protective film made of Aλ and having a thickness of 200 μm was formed on the ferromagnetic metal layer 1- made of 2ONi.

Next, Ni was heated and evaporated again under a vacuum of 5X10-5 Torr, and at the same time oxygen gas was evaporated at 300 m1/min.
Ni vapor flow at a rate of N is deposited obliquely on the first layer of the protective film made of AJ.
Two layers of a protective film having a thickness of 200 mm were formed.

Thereafter, it is cut to a predetermined width, and a ferromagnetic metal layer 2.degree. and a first protective film layer 3. are formed on a polyester film 1 as shown in FIG. A magnetic tape was produced in which the second protective film layer 4 was sequentially laminated.

A magnetic tape was made in the same manner as in Example 1, except that Cr was used instead of AJ in forming the first layer of the protective film in Example 1.

K Bloodiness 1 A magnetic tape was produced in the same manner as in Example 1, except that Ti was used instead of Aλ in forming the first layer of the protective film in Example 1.

Disaster relief” eyes.

A magnetic tape was produced in the same manner as in Example 1 except that Ni-20Fe was used in place of Ni in the formation of the second layer of the fi film.

After sequentially laminating a ferromagnetic metal layer, a first protective film layer, and a second protective film layer on a polyester film in the same manner as in Example 1, a diluted mixed solution of Vibe Nox AR and Fonblin Z ( 0,0510,05 wt%) was coated and formed, and a lubricant layer of 200 mm thick consisting of Vydax AR and Fonblin Z was applied, and then cut to a predetermined width to form a polyester film as shown in Figure 2. ferromagnetic metal layer 2. First protective film layer 3, second protective film layer 4. Lubricant layer 5
A magnetic tape was made by sequentially laminating the following layers.

Person J1 Exclamation - After diagonally depositing the ferromagnetic metal layer and vertically depositing the first layer of the protective film to form the first layer of the protective film that does not have a columnar grain structure, the second layer of the protective film is deposited as described above. A magnetic tape was produced in the same manner as in Example 1, except that the deposition was performed obliquely in a direction opposite to that of the ferromagnetic metal layer. The cross-sectional structure of this tape is shown in FIG.

A magnetic tape was produced in the same manner as in Example 1, except that the second layer of the protective film was omitted in the formation of the protective film in Example 1.

A magnetic tape was produced in the same manner as in Example 1, except that the first layer of the protective film was omitted in the formation of the protective film in Example 1.

The magnetic tapes obtained in each example and comparative example were tested for corrosion resistance and abrasion resistance. Corrosion resistance test was carried out by subjecting the obtained magnetic tape to 1 ppm of succinic acid gas (802) at 35°C.
The saturation magnetization 11 was measured using a sample vibrating magnet (VSM) after being left in a 75% RH condition for 24 hours, and the saturation magnetization of the magnetic tape before being left was taken as 100%, and the value compared with this indicates the deterioration. I checked the rate.

The wear resistance test was conducted by recording a 5 MHz signal on a magnetic tape using a commercially available VTR tape deck and measuring the still life at the time of birth.

The measurement results are summarized in Table 1 below.

[Effects of the Invention] As is clear from the results shown in Table 1, the magnetic tapes of the present invention obtained in Examples 1 to 6 had higher saturation than the conventional magnetic tapes obtained in Comparative Examples 1 and 2. Magnetization: it
The deterioration rate is small and the life span is long.

From this fact, it is understood that the magnetic recording medium obtained by the present invention has further improved corrosion resistance and wear resistance.

4, Drawing) 1'1vI111. 1, 2 and 3 are partially enlarged sectional views of the magnetic recording medium of the present invention.

■...Polyester film (substrate), 2...Ferromagnetic metal layer, 3...First protective film layer, 4...Second protective film
Layer, 5...Lubricant layer Special 1; 1 Applicant [11 γ Maxell Co., Ltd. Attorney 1- Yasushi Kajiyama, Patent attorney [- Tomio Yamaki

Claims (1)

[Claims] (1) A magnetic material formed by forming a ferromagnetic metal layer on a substrate, forming a first protective film layer on this ferromagnetic metal layer, and further forming a second protective film layer on this first protective film layer. In the recording medium, the first layer of the protective film is made of at least one of Al, Cr, and Ti.
1. A magnetic recording medium containing at least one element, and further characterized in that the second layer of the protective film contains Ni as a main component.