JPH034967B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to magnetic recording media such as magnetic tapes, disks, cards, etc., and methods for manufacturing the same, and in particular, aims to improve a medium having a ferromagnetic metal layer as a magnetic recording layer and to provide a method for manufacturing the medium. In general, in the field of magnetic recording, the usefulness of using a ferromagnetic metal thin film as a magnetic recording layer for short wavelength recording is well known. However, the biggest problem when using such media on a practical level is how to protect the ferromagnetic layer from corrosion and wear. Conventionally, this kind of problem has been common to ferromagnetic films obtained by either wet plating or vapor deposition, and improvements have been made in various fields. Basically, the purpose is to improve the resistance of the ferromagnetic layer and to strengthen weak points with a protective layer. Therefore, Co-P, Co-Ni-P plated films, Co,
Many types of materials have been proposed as protective layers for deposited films such as Co-Ni and Co-Cr. For example, Ni・
W alloy (JP-A-51-43110), Ni-B alloy (JP-A-52-2405), Ni alloy layer with increased hardness by heat treatment (JP-A-51-102605), Thin alloy films such as Ni/Cr alloy (Japanese Unexamined Patent Publication No. 53-73108) are used as protective layers; 127203), Si-Si oxide with Cr interposed between the magnetic layer (Japanese Unexamined Patent Publication No. 127204/1983),
Silicon nitride compound (JP-A-55-73931),
A boride layer of La (Japanese Unexamined Patent Publication No. 11626/1982), a monomolecular layer of saturated fatty acid (Japanese Unexamined Patent Publication No. 7500/1989), and a layer containing an antioxidant in a lubricating liquid layer (Unexamined Japanese Patent Publication No. 1983-11626), a monomolecular layer of saturated fatty acid (Japanese Unexamined Patent Publication No. 50-7500), (Japanese Patent Publication No. 51-20805) have been proposed, but a common drawback of these is that the thickness of the protective layer is limited due to constraints on spacing loss in short wavelength recording. Another point of difference is the increase in the coefficient of friction due to the extremely smooth surface of the substrate suitable for short wavelength recording (which in turn directly reflects the properties of the vapor layer surface). The protective layer that compensates for these two points is
The above proposal was insufficient if it was intended to be adapted to a consumer VTR system. This is because it must withstand sliding with a magnetic head rotating at a high relative speed of about 3 m/sec to 5 m/sec for a long time in various actual usage environments. The present invention has been made in view of these points, and it is an object of the present invention to provide a magnetic recording medium having a protective layer that exhibits excellent corrosion resistance and durability, regardless of its form, and to provide a method for manufacturing the same. That is. The minimum components of the magnetic recording medium according to the present invention are a nonmagnetic substrate, a ferromagnetic metal layer, and a protective layer made of a metal-containing carbon fluoride polymer disposed on the surface of the ferromagnetic metal layer. In addition, the presence or absence of, for example, a layer to assist running properties on the back side of the substrate, a non-magnetic layer placed between the substrate and the ferromagnetic layer, etc. has no direct relation to the present invention. You can freely choose from other purposes. Therefore, regarding the manufacturing method, at least the process of obtaining a ferromagnetic metal layer by vapor deposition and starting from a carbon fluoride monomer are required.
It is characterized by having a step of plasma polymerizing a metal such as Mo, W, Cr, Co, Ni, etc. as a target, and other steps may be added depending on the configuration of the medium. Embodiments of the present invention will be described below with reference to the drawings. Example 1 On a polyethylene terephthalate film (9.5 μm thick, 500 mm width) as a substrate,
5×10 ^-5 Torr in a vacuum chamber evacuated to 10 ^-5 Torr
Oxygen is forcibly introduced from outside the tank so that
At an average deposition rate of 1300 Å/sec, a magnetic layer of 90% Co and 10% Ni was formed to a thickness of 0.13 μm using a vapor flow with an incident angle of 40° or more to prepare an original magnetic tape. This original fabric was treated in another vacuum tank, and a metal-containing carbon fluoride polymer layer was formed on the magnetic tank. In other words, 13.56M was targeted at 99.99% pure Mo.
A high frequency of Hz is applied to the target to generate a glow discharge. The discharge sustaining gas was C ₂ F ₄ gas, and the amount introduced was controlled by detecting the pressure. FIG. 1 shows a magnetic tape according to the invention. In the figure, reference numeral 1 denotes a magnetic layer formed on a substrate 2, on which a polymer layer 3 is formed. Note that since it is difficult to accurately measure the thickness of the polymerized layer, it was managed by tape output. The experimental results are shown in Tables 1 and 2 below. Note that tape A in Tables 1 and 2 is
2.0 to 13.56MHz, 350W, 0.1Torr _{C2F4 plasma}
If to is the thickness of the polymerized layer when exposed for 2 seconds, tape B was exposed for 4 seconds and tape C was exposed for 6.0 seconds (the thickness was confirmed to be proportional to time based on plasma stability and other calibration experiments). ), in this case, the thickness of each polymer layer is 2to and 3to, and the reproduction output at a recording wavelength of 0.8 μm is ±0.3 dB, ±
0.3 dB, ±0.4 dB, and the space loss can be ignored. However, even with this level of thickness,
The protective effect of this protective layer was remarkable, and significant differences as shown in Tables 1 and 2 were confirmed.
Three conventional examples were used: one in which a monomolecular layer of saturated fatty acid was formed, one in which a silicon nitride film was formed with a thickness of 270 Å using a sputtering method, and a polymer film (fluorine-based resin) that did not contain Mo. Two tests were conducted on each tape as follows. (Test 1) A 1/2 tape is wound 100m onto an open reel, a sine wave with a recording wavelength of 0.8μ is recorded, and the output is reduced by leaving it in an environment of 60℃ and 90%RH for 1, 5, and 10 weeks and playing it back. The frequency of clogging was compared. Note that the tape feeding speed was 2.4 cm/sec, and the relative speed was 4.2 m/sec. The test results are shown in Table 1.

【table】

[Table] (Test 2) The same tape was tested on SUS304 in an environment of 35℃ and 85%RH.
A post (diameter 10
Table 2 shows the results of examining the changes in the coefficient of friction by wrapping the rubber around the shaft (mm) at 180° and running it repeatedly at 2.4 cm/s.

[Table] As is clear from the above two test results, it is understood that the durability and stability of the tape according to the present invention are unmatched by conventional tapes.
Furthermore, it is noteworthy that even under dry conditions of 45°C and 10% RH, which are extremely unfavorable to friction, a sharp difference is observed. Example 2 Polyethylene terephthalate film (11.5μ
m thickness, 500 mm width) with a vacuum of 1 × 10 ^-5 Torr,
After forming iron to a thickness of 0.15μm at an incident angle of 65° or more, an oxygen glow discharge of 0.08Torr (500V1.3A) is applied.
for 2 seconds. Next, add C ₂ F ₆ gas at 0.33N/
Introduce min and maintain pressure at 0.06Torr, 13.56MHz
High frequency waves were applied to a target holder using Co (99.99% purity) as a target to generate high frequency plasma, and a fluorinated carbon polymer film containing Co was formed on the magnetic layer made of iron to serve as a protective film. . Three levels of estimated thickness were investigated in the range of 60 to 130 Å.
In this range, at a recording wavelength of 0.8 μm, no change in playback output was observed depending on the presence or absence of the protective film, and the same test as in Example 1 showed that almost the same improvement effect in protection performance was obtained compared to the conventional example. It was confirmed that From the above, the presence or absence of a protective film can be well understood regardless of the magnetic layer. Example 3 Polyethylene terephthalate film (10.5μ
m thickness, 500 mm width) was evacuated to 5.5 × 10 ^-6 Torr in advance, and then oxygen was introduced from the outside at 1.0 N/min to create a vacuum of 2.5 × 10 ^-5 Torr.
Co80%Ni20% was deposited at 46° or more to form a 0.13μm thick magnetic layer, and then 6.5×
Exhaust to 10 ^-5 Torr and inject C ₃ F ₈ from the outside.
A high frequency of 13.56 MHz was applied to a W (99.99% purity) target in a mixed gas system with a vacuum of 0.07 Torr in which 0.055 Torr of oxygen was introduced and 0.015 Torr of oxygen was introduced to make the W-containing plasma polymerized film magnetic. formed on the layer. The effect of intervening oxygen was that almost the same polymer film was formed in a shorter time, which indicates that it had the effect of accelerating the formation speed of the polymer film. Three levels of estimated thickness of 70 Å, 140 Å, and 310 Å were selected for the fluorinated carbon protective layer containing W formed as described above, and the protective performance was investigated. The results were the same as in Example 1. Note that the thickness of the protective layer is estimated to be 30 Å by normalizing with time from the conditions for obtaining the thickness of 310 Å.
A protective layer with a thickness of 10 Å was also examined in the same manner. As a result, if the thickness is estimated to be 10 Å, in test 1,
The output decreased after being left unused for 1 week and 5 weeks.
Although the protective film was 0.6 dB and -1.2 dB, which is almost the same level as the conventional protective film, the clogging was 0.3/min and 0.4/min after being left for 1 week and 5 weeks, respectively. 2, the friction coefficient change rate after 50 passes and 500 passes is +16% and +28%, which has the effect of maintaining practical values, and has a protective effect on carbon fluoride polymer films containing metals. It can be said that this shows the excellence of The present invention has confirmed the same effect even when _CF4 is used as a starting monomer, and furthermore, when the magnetic layer has an axis of easy magnetization perpendicular to the substrate and is recorded and reproduced by a ring head, and when it is used for magnetic tape. The same effect can be seen not only in sheets and disks using polyamide or polyimide as a substrate, but also in disks with metal substrates such as aluminum, and thus is effective regardless of the type of magnetic layer or the formation method. It is. In addition, as a target, Cr,
Similar effects were confirmed when Ti and Ni were selected. Furthermore, as another effect of the present invention, it is expected that the metal-containing carbon fluoride polymer film will improve the adhesive strength with the metal magnetic layer, and as a result, the abrasion resistance at 30°C and 80% RH (the head is made of ferrite). It was also confirmed that there was a significant improvement in As described above, according to the present invention, a magnetic recording medium with excellent corrosion resistance and running properties can be easily obtained.

[Brief explanation of the drawing]

The figure is a cross-sectional view of a magnetic recording medium according to the present invention. 1...Magnetic layer, 2...Substrate, 3...Polymerization layer.

Claims (1)

[Claims] 1. A ferromagnetic metal layer on a non-magnetic substrate, and a protective layer made of a carbon fluoride polymer containing metal on the ferromagnetic metal layer. magnetic recording media. 2. Forming a ferromagnetic metal layer on a non-magnetic substrate by vapor deposition, plasma polymerizing carbon fluoride monomer vapor using metal as a target, and forming a carbon fluoride polymer containing metal on the metal layer. 1. A method of manufacturing a magnetic recording medium, comprising the step of forming a protective layer by combining.